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日本語の「Vに行く/来る」と「に行って/来てV」 の違いについて
Get PDF本研究は、JST次世代研究者挑戦的研究プログラムJPMJSP2125の財政支援を受けたものです。departmental bulletin pape
Colloidal Synthesis of Ag2MnSnS4 Quantum Dots for Bioimaging Applications
No full textAg2MnSnS4 (AMTS), a member of the multinary I2–II–IV–VI4 compound family, exhibits a high absorption coefficient and intrinsic magnetic properties. While bulk AMTS crystals were synthesized via high-temperature solid-state methods, reports of AMTS quantum dots (QDs) remained scarce. Here, we report the first colloidal synthesis of AMTS QDs by optimizing reaction temperature and precursor composition. AMTS QDs obtained at 250 °C were spherical or polygonal with an average size of 5.4 nm or less. Decreasing the Ag fraction in precursors produced Ag-deficient, Mn-rich QDs, exhibiting high tolerance to nonstoichiometry. Their absorption spectra were blue-shifted, and the energy gap increased from 1.95 to 2.36 eV with a decrease in the Ag+/metal cation ratio in the precursors from 0.50 to 0.05. Although no photoluminescence (PL) was observed at room temperature, a broad PL peak appeared at 77 K around 740–760 nm. ZnS coating on AMTS QDs enhanced the PL, giving a broad emission at 690 nm. The magnetic properties originated from unpaired 3d electrons of Mn2+. For bioimaging applications, ZnS-coated AMTS (AMTS@ZnS) QDs were further modified with 3-mercaptopropionic acid, enabling stable dispersion in water without compromising the optical and magnetic properties. The hydrophilic AMTS@ZnS QDs exhibited high longitudinal relaxivity (r1), 19 mmol (Mn2+)−1 dm3 s–1, surpassing commercial Mn-based complexes (r1 < 10 mmol–1 dm3 s–1). Although the T1-weighted MRI intensity was similar at a fixed Mn2+ concentration, the QDs prepared with Ag/metal = 0.17 showed 1.7-fold higher relaxivity per QD than those with 0.44. In vivo MRI confirmed a clear signal enhancement at injection sites. The QDs internalized by cells were detectable by MRI in living animals. Given their negligible cytotoxicity compared to Cd-based QDs, AMTS QDs represent a promising next-generation MRI contrast agent, with additional potential for dual-mode bioimaging upon further PL optimization.journal articl
Tinnitus and Sensory Dysfunctions: A Cohort Study from Health Checkups before and during COVID-19 Endemic
Get PDFIntroduction: Tinnitus and smell dysfunction have been reported to be associated. The long-term course of tinnitus and sensory dysfunctions, including olfactory and gustatory dysfunctions, following COVID-19 infection requires further study. Materials and Methods: A cohort study of tinnitus and sensory dysfunctions before and during the COVID-19 pandemic was conducted through health checkups in a rural area in Japan. Five hundred ten participants attended health checkups in August 2019, 434 in 2023, and 437 in 2024. Two hundred twenty-five participants attended the 2019 and 2023 health checkups, and one hundred seventy-one participants attended all three. The subjects included people 40 years of age or older. The questionnaire included information on tinnitus, hearing, vertigo, headache, smell, taste, and lifestyle habits. In 2023, the questionnaire included questions about COVID-19. Results: Tinnitus, hearing impairment, and smell dysfunction were associated. Fear and anxiety about COVID-19 infection were significantly associated with tinnitus after adjusting for age and sex. Irregular sleep time and fewer sports and exercise habits were significantly associated with tinnitus, not smell or taste dysfunction. In an investigation of identical persons, deterioration of tinnitus was conspicuous in 2023 compared to 2019 in persons with strong fear and anxiety about COVID-19. Conclusions: Tinnitus is related to lifestyle habits compared to other sensory disorders. Fear and anxiety about COVID-19, rather than COVID-19 infection itself, significantly influenced tinnitus during the COVID-19 pandemic in rural areas.journal articl
C(sp3)-H alkylation using H2O catalyst for hydrogen atom transfer over Ag-loaded TiO2 photocatalysis
No full textWe report the direct C(sp3)single bondH bond alkylation using interfacial H2O-covered, Ag nanoparticle-loaded TiO2 (H2O@Ag/TiO2) semiconductor photocatalyst, where H2O catalyst induces hydrogen atom transfer (HAT) without wasteful by-products. For the efficient and selective transformation, it is critical to use a mixed solvent system composed of CH3CN and H2O in an appropriate ratio and to employ relatively electrophilic alkenes as alkylating agents. A wide range of ethers were alkylated selectively at their α-C(sp3)single bondH bonds adjacent to the oxygen atoms in good to excellent yields, regardless of their water affinities (water-miscible or poorly water-soluble), molecular frameworks (cyclic or acyclic), or physical states (liquid or solid). Cyclohexane with no ethereal oxygen, which is almost entirely immiscible with water, also underwent the C(sp3)single bondH alkylation under a similar H2O@Ag/TiO2-photocatalyzed system.journal articl
Just a strategic move? Exploring good reasons for self-determination referendums through the case of East Timor
Get PDFUsing referendums to settle the question of sovereignty might look intuitive, but self-determination is not always accompanied by a referendum empirically, and the existing literature largely points to politicians’ instrumental motivations to hold self-determination referendums. Referendums are also notorious for their zero-sum nature. What exactly then makes referendums essential for self-determination? By analysing East Timor’s 1999 referendum, this article uncovers three reasons referendums should be held to accurately ascertain the population’s wishes in non-democratic contexts: the fear that representatives might be bribed or threatened in a hypothetical indirect vote; the simple nature of referendums; and the lack of democratic tradition.Published online: 16 Mar 2023journal articl
Environmentally Friendly Synthesis of Polymer Nanoparticles in a Packed Reactor Using Glass Beads
Get PDFPolymeric particles less than 100 nm in size (polymer nanoparticles), which are useful in the fields of medicine and so on, are synthesized through emulsion polymerization, wherein surfactants are essential for maintaining their dispersion stability, contaminating particle surfaces and causing high environmental pollution. The soap-free emulsion polymerization (SFEP) of styrene in a packed reactor using microglass beads enables the synthesis of polymer nanoparticles without surfactants. Ultraviolet irradiation is used for radical polymerization using an initiator during the SFEP of styrene. The reaction space in the packed reactor is controlled by the size of glass beads to be filled in the reactor. A decrease in the size of the glass beads narrows the reaction space, causing the average polystyrene particle size to reach 27.3 nm and suppress convection flow by the wall of the glass beads, thereby limiting particle motion and preventing particle growth through particle collisions.First published: 09 May 2024 (Online Version of Record before inclusion in an issue)journal articl
災害金融市場の強化と政策対応 : 東南アジアを例に
Get PDFThe number of disasters is increasing in Southeast Asia. How to strengthen financial response to disasters is key. Amid increasing government fiscal burden, Southeast Asian countries are currently in the middle of a transition to more market-based solutions in disaster risk financing. Such efforts are outlined in Disaster Risk Financing and Insurance (DRFI) strategies recently initiated by many Southeast Asian countries. In particular, this paper discusses the importance to strengthen disaster insurance markets. The theoretical discussion in this paper examines different types of government interventions and their different impact on equilibrium in insurance markets. The paper also discusses the policy responses to strengthen disaster risk financing initiatives in Southeast Asia. Government support to insurance premium may be needed in Southeast Asian countries, though the level and duration of such support should be carefully implemented. Another important point of the paper is to highlight the need to enhance financial literacy to broaden access to insurance markets in Southeast Asia.departmental bulletin pape
儀礼空間から読み解く皇都・東京
Get PDFWith the transfer of the capital to Tokyo in 1869, the Imperial Palace was moved from Kyoto to Tokyo. From the Meiji period to the pre-war Showa period, Tokyo was often referred to as Koto or Teito, which means the city where the emperor lives. After World War II, the emperor’s political position changed significantly as the modern emperor system was replaced by a symbolic emperor system, and the term Koto or Teito was no longer used. Today, as Tokyo has expanded and become one of the world’s leading cities with international influence, the fact that it is the city where the emperor lives is no longer something that people are fully aware of, or actively mention. However, Tokyo, which became Koto in the early Meiji period, has remained Koto for about 150 years. This fact is rarely discussed head-on in the fields of architectural history and urban history, but it is a key issue when approaching the political theme of the Emperor System from the perspective of urban space. With the above in mind, this paper discusses the dynamic relationship between politics and urban space by examining the ceremonial spaces related to the Emperor System from the Meiji period to the present, from the perspective of viewing Tokyo as the city where the Emperor lives.departmental bulletin pape