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医療機関における放射線業務従事者の被ばく線量管理の課題ー放射線マネジメントシステム導入支援事業参加機関へのアンケート調査ー
No full text目的：本研究は，放射線マネジメントシステム（放射線MS）導入支援事業に参加した医療機関を対象に，被ばく線量管理の現状と課題を明らかにし，今後の管理体制の構築・改善に資する情報を示すことを目的とした．対象と方法：2022年度に放射線MS導入支援事業に参加した全国の医療機関を対象にWeb上で質問紙調査を実施し，有効な回答および研究への情報利用の同意が得られた143機関を分析対象とした．調査項目は，放射線管理体制（5項目），放射線業務従事者の確認・管理，個人線量計着用に関する周知・啓発等であった．質問紙の各項目を単純集計およびχ2 乗検定を用いて分析した．放射線管理体制の5項目に関し，放射線管理体制を構築する際に取り組むとよい順序を検討するため，相関分析，ロジスティック回帰分析，決定木分析（CART分析），パス解析を行った．結果：143機関のうち，医療従事者の放射線被ばく管理組織（委員会等）が設置されていたのは46.9％，医療機関の管理者が放射線管理に対する方針や指針を明示していたのは55.9％であった．放射線業務従事者の兼業について，放射線管理担当者が，自施設の放射線業務従事者が他施設で放射線業務に従事している（以下「放射線業務を行う兼業に行っている」という）かどうかを把握していたのは32.6％，他施設の放射線業務従事者が自施設で放射線業務に従事している（以下「放射線業務を行う兼業に来ている」という）かどうかを把握していたのは35.0％であった．個人線量計の適正な装着について，周知・啓発がなされていなかったのは33.6％の機関であった．診療所－病院間での差異を検討したところ，労働安全衛生マネジメントシステム（OSHMS）は病院よりも診療所で導入が進んでいること，放射線業務を行う兼業に行っているかどうかおよび放射線業務を行う兼業に来ているかどうかも，病院よりも診療所でよく把握できていることが示された．放射線管理体制の構築においては，被ばく管理組織の設置が重要であるが，それを促進するためには，方針や指針の明示，監査の仕組み作りが優先的に取り組むとよい項目であることが示された．考察と結論：本調査により放射線管理体制の整備，放射線管理担当者の選任方法，放射線業務従事者の個人線量管理等に係る課題が明らかになった．また，放射線管理体制を構築する際に，優先的に取り組むとよい項目も明らかになった．課題解決には，まず医療機関の管理者が放射線管理に係る方針や指針を明示し，監査の仕組み作りを進め，被ばく管理組織の設置を推進することが求められる．また，医療機関の管理者のリーダーシップを強化すること，放射線MSを導入し管理体制を維持改善することが効果的であると考えられた．journal articl
Design of Active Hopping Sites via Trace Trivalent Cation in IT-SOFC Anode
No full textTo improve the performance and durability of intermediate-temperature solid oxide fuel cells (IT-SOFCs), a small amount (less than 1200 ppm) of trivalent cations (Rh³⁺ or Fe³⁺), similar to Y³⁺ in Y₂O₃, was doped onto the surface of yttria-stabilized zirconia (YSZ) in the anode layer. This doping led to a ninefold increase in current density at 973 K compared to undoped cells. First-principles surface calculations revealed that the enhancement is due to delocalized electrons near the three-phase boundary and improved surface oxygen diffusion. These findings establish a guiding principle for material design that leverages YSZ’s unique physical properties for IT-SOFC applications.journal articl
Uniform electron benchmark for the first-principles -Eliashberg theory
No full textWe investigate the numerical behavior of the Eliashberg equations for phonon-mediated superconductivity, incorporating normal-state self-energy calculations within the consistent approximation. We account for the full wavenumber and frequency dependences of both the screened Coulomb interaction and phonon-mediated attraction. We present results for the prototypical uniform electron gas system with model Einstein phonons at temperatures of a few kelvin. At extremely low temperatures, we efficiently execute the required convolutions of Green's functions and interactions in Matsubara frequency and wavenumber using intermediate representation and Fourier convolution techniques. In particular, we elucidate the interplay between electron-phonon -mass and -mass renormalizations of the electronic self-energy in determining the normal-state effective mass, spectral weight and the superconducting transition temperature. The electron density regimes where the plasmon effect enhances or suppresses the phonon-mediated superconductivity on top of the static Coulomb effect are revealed. We compare our comprehensive Eliashberg calculation results with those from density functional theory for superconductors, where the functionals have been constructed with reference to Eliashberg theory. Our model, methods, and results provide a valuable benchmark for first-principles superconducting calculations that treat screened Coulomb interaction effects non-empirically.journal articl
Retro-Diels–Alder-Triggered Supramolecular Polymerization of Tetrabenzoporphyrin into Pyramidal Aggregates
No full textSupramolecular polymerization of π-extended compounds with hydrogen-bonding sites remains challenging, especially in high concentrations, due to their limited solubility in nonpolar solvents. Herein, we report an indirect method incorporating a thermal precursor approach for the supramolecular polymerization of a poorly soluble tetrabenzoporphyrin (BP) derivative with multiple hydrogen-bonding sites and chiral cholesterol groups (BPChol). Polymerization in the nonpolar solvent tetralin is induced by a retro-Diels–Alder reaction of the highly soluble precursor (CPChol) to BPChol in the hot solution, followed by natural cooling, as confirmed by monitoring absorption spectra. The emergence of circular dichroism signals in the BP absorption regions corroborates the formation of aggregates with supramolecular chirality, as the first chiroptical characterization of BP aggregates. Detailed structural analyses using high-resolution microscopies reveal a unique pyramidal multilayer structure with a spiral nature. Additionally, faster cooling produces monolayer nanosheets, which differ from the multilayer structures formed upon natural cooling. This is due to a different nucleation process in the cooperative polymerization. By using the nanosheets as seeds, seed-induced polymerization into extended sheets is confirmed. Notably, the indirect precursor method using CPChol allows polymerization at high concentrations (mM level) to afford the micro-sized pyramids, never obtained by the direct method using BPChol.journal articl
Thermoluminescence properties of Cr, Si, and Mg co-doped Al2O3 ceramics plates under proton beam irradiation
No full textThis study evaluates the thermoluminescence (TL) properties of Cr, Si, and Mg co-doped Al2O3 (Al2O3:Cr,Si,Mg) ceramic plates under 200 MeV proton beam irradiation, aiming to assess their potential for high-resolution two-dimensional dosimetry in proton therapy. Spectral measurements revealed a dominant TL emission peak at 693 nm, corresponding to the 2E → 4A2 transition of Cr3+ ions. The glow curves exhibited consistent peak temperature and shape regardless of dose and linear energy transfer (LET), indicating the stability of the trap and recombination centers. The TL response showed excellent linearity with absorbed dose, agreeing within ±1.5 % with ionization chamber measurements, and demonstrated minimal dependence on LET. Furthermore, large-area (200 mm × 200 mm) TL ceramic plates were used to obtain two-dimensional dose distribution maps. The off-axis ratio and percent depth dose distributions measured using TL imaging were in good agreement (within ±1–6 %) with those obtained from standard dosimeters, and the spatial resolution reached 156 μm. These results suggest that Al2O3:Cr,Si,Mg ceramics are suitable for accurate, reusable, and high-resolution proton dosimetry, offering a promising alternative to conventional film- or ionization-based detectors for quality assurance in particle therapy.journal articl
Initial plasma achieved within engineering constraints in the PLATO tokamak
No full textIn order to save flux consumption and lessen engineering requirements, the achievable toroidal loop voltagetends to be lowered in modern tokamaks. In such devices, careful optimization of the plasma startup scenariois often required to achieve a successful tokamak discharge. The PLATO tokamak, which is recently built atKyushu University, also faces challenges in the plasma startup. PLATO employs an air-cored central solenoidthat limits the loop voltage and creates stray magnetic fields. In addition, only simple capacitor banks withmodest maximum charging voltages are available for the generation of the poloidal magnetic and toroidalelectric fields in the initial operation. To realize the breakdown and plasma current ramp-up under thoseconstraints, the configuration of coils and capacitor bank settings has been optimized to produce sufficient loopvoltage while minimizing the stray field inside the vacuum chamber at the onset of the discharge. Throughthis optimization, a tokamak discharge with a plasma current of 30 kA and a pulse duration of 20 ms hasbeen achieved.journal articl
Quantification of monoamine oxidase B expression with C-SL25.1188 for imaging reactive astrocytes in patients with Alzheimer's disease.
No full textAstrocyte reactivation can be assessed using positron emission tomography (PET) ligands targeting monoamine oxidase B (MAO-B). C-SL25.1188 binds reversibly to MAO-B, allowing precise density measurements, but requires invasive arterial sampling. This study aimed to develop a simplified, noninvasive method to quantify MAO-B with C-SL25.1188 PET in Alzheimer's disease (AD).journal articl
不定性に宿る希望の認知科学
No full text「不定性と逆境のなかの希望」は不定性を制御すべき”ノイズ”ではなく、生成と変容の条件とみなす視座から、人間のこころと行動を多角的に捉え直すことを目的とする。認知、身体、社会、芸術、倫理の交差点において、不定性はしばしば ”創造的契機” となり、同時に ”耐えるべき状態” としても現れる。私たちはその両義性のただなかにいる。不定性や逆境をさけるのではなく、あえてその中にとどまり、知覚し、意味を見出そうとする態度は、教育、医療、芸術、社会制度、AI設計に至るまで多様な領域で再評価されつつある。本特集はそのような不定性の価値に焦点を当てた、認知科学における新たな射程を提案するものである。journal articl
Study of chemical content effects for oxide formation on HIPed interface during the fabrication process by comparison of F82H steel with FeCrAl alloy
No full textReduced-activation ferritic/martensitic steel (F82H) is considered as a promising structural material for the fusion blanket structural system following the DEMO reactor. For blanket fabrication, hot isostatic pressing (HIP) is employed for the production of components with complex geometries. A key challenge associated with the HIP processing of F82H steels is the formation of silicon oxide at the HIPed interface, which results in reduced joint toughness. This study investigates the correlation between the thermodynamic stability of oxides and researches whether the silicon precipitation is the special property of silicon or not. An FeCrAl alloy containing Si was selected for comparison with F82H steel, and both materials were subjected to identical processing conditions. Silicon oxides were observed at the F82H steel-HIPed interface, whereas aluminum oxides were observed in the FeCrAl alloy. No Si precipitation or accumulation was detected at the HIP-treated interface of the FeCrAl alloy. This research showed that the silicon precipitation on F82H HIPed interface is not a special property of silicon but a general behavior of the elements along the thermodynamics and formation energy of oxides.journal articl
Arbitrary polarization control with a segmented APPLE-II undulator
No full textA newly developed four-segmented APPLE-II undulator enables arbitrary polarization control in the soft to tender X-ray region. The undulator is installed at NanoTerasu BL13U, aiming for X-ray absorption spectroscopy over a wide energy range, 180–3000 eV, with versatile photon polarizations. By adjusting the phase difference of the synchrotron radiation using electromagnetic phase shifters, arbitrary orientations of linear polarization were obtained from left and right circularly polarized radiation. Elliptically polarized radiation was also generated from vertical and horizontal linearly polarized radiation. In addition, the ellipticity angles were successfully controlled. Circularly polarized radiation in the tender X-ray region is considered to be achieved by utilizing the third harmonic. Methods and performance of polarization control of the segmented APPLE-II undulator using the phase shifters are presented.journal articl