Study of the Large-scale Temperature Structure of the Perseus Cluster with Suzaku

We report on a study of the large-scale temperature structure of the Perseus cluster with Suzaku, using the observational data of four pointings of 30' offset regions, together with the data from the central region. Thanks to the Hard X-ray Detector (HXD-PIN: 10 - 60 keV), Suzaku can determine the temperature of hot galaxy clusters. We performed the spectral analysis, by considering the temperature structure and the collimator response of the PIN correctly. As a result, we found that the upper limit of the temperature in the outer region is $\sim$ 14 keV, and an extremely hot gas, which was reported for RXJ 1347.5-1145 and A 3667, was not found in the Perseus cluster. This indicates that the Perseus cluster has not recently experienced a major merger.Comment: 17 pages, 25 figures, accepted for Publications of the Astronomical Society of Japan, references adde

Separation Between Silicon and Aluminum Powders Contained Within Pulverized Scraped Silicon-Based Waste Solar Cells by Flotation Method

There are few study examples on the separation of metals by floating method. In this study, separation of silicon and aluminum, which are the main components of silicon-based solar cell module, was carried out by floating method in order to purify silicon from waste solar cell module. The selection of surfactant, control of electric charge, wettability of the solid particles, surface tensions, and bubble surface area are important for separation of solids by floating method. Sodium dodecyl sulfate (SDS) can increase the hydrophobicity of aluminum powder due to the difference of surface potentials between silicon and aluminum. SDS behaves as a collector of aluminum as well as a frothing agent to decrease the bubble size. At a SDS concentration of 2 g/L and sample dipping time of 10 min, 80.1 mass% of aluminum was floated and separated, and the sedimentary silicon reached a purity of 90.7% from a mixture of 50 mass% aluminum and 50 mass% silicon. Finally, at a pH value of 7.0, SDS concentration between 1.0 and 2.5 g/L and air flow rate of 2.5 L/min (STP) were suitable experimental conditions to purify silicon from a mixture of silicon and aluminum by flotation separation method

Self-consistent picture of the mass ejection from a one second-long binary neutron star merger leaving a short-lived remnant in general-relativistic neutrino-radiation magnetohydrodynamic simulation

We perform a general-relativistic neutrino-radiation magnetohydrodynamic simulation of a one second-long binary neutron star merger on Japanese supercomputer Fugaku using about $72$ million CPU hours with $20,736$ CPUs. We consider an asymmetric binary neutron star merger with masses of $1.2$ and $1.5M_\odot$ and a `soft' equation of state SFHo. It results in a short-lived remnant with the lifetime of $\approx 0.017$\,s, and subsequent massive torus formation with the mass of $\approx 0.05M_\odot$ after the remnant collapses to a black hole. For the first time, we confirm that after the dynamical mass ejection, which drives the fast tail and mildly relativistic components, the post-merger mass ejection from the massive torus takes place due to the magnetorotational instability-driven turbulent viscosity and the two ejecta components are seen in the distributions of the electron fraction and velocity with distinct features.Comment: Accepted in PRL. 8 pages, 5 figure, Supplement Material is https://www2.yukawa.kyoto-u.ac.jp/~kenta.kiuchi/anime/FUGAKU/FUGAKU2022_Supplement_Material.pd

Actinide-boosting r Process in Black Hole-Neutron Star Merger Ejecta

We examine nucleosynthesis in the ejecta of black hole-neutron star mergers based on the results of self-consistent, long-term neutrino-radiation-magnetohydrodynamics simulations for the first time. We find that the combination of dynamical and post-merger ejecta reproduces a solar-like r-process pattern. Moreover, the enhancement level of actinides is highly sensitive to the distribution of both electron fraction and the velocity of the dynamical ejecta. Our result implies that the mean electron fraction of dynamical ejecta should be ~ 0.05-0.08 in order to reconcile the nucleosynthetic abundances with those in r-process-enhanced, actinide-boosted stars. This result provides an important constraint for nuclear equations of state.Comment: 5 pages, 4 figure

Support System for Self-Overcoming of Problem-Solving Failures Using Problem Simplification and Practical Use in Elementary Physics Exercises

問題演習において，問題解決に失敗した学習者に対して行われる活動は一般的にその問題に対する解答・解説などのその問題の解決に関する直接的な教授であった．しかしこれは学習者にとって受動的な学習であったといえる．学習者に能動的に学ばせる上では，直接的にその問題の解き方を教えるのではなく，問題解決失敗を自分で克服させることが望ましいが，解決に失敗している学習者が単独でそれを克服することは難しいことも明らかである．本論文では直接的な教授活動なしで問題解決の失敗を克服する活動を自己克服と呼び，その自己克服を支援する方法として，問題中のできる部分とできない部分を切り分けながら演習を行う単純化方略を提案する．これは個々の問題の構造とその構造に基づく問題間の関係性が明確に定義され，それらの差分の中に学習者の困難さが存在すると仮定できる場合に実現可能な方法である．本論文では，このような条件を満たすドメインである初等力学を対象として，この単純化方略を用いて問題解決失敗の自己克服を支援する演習システムをタブレットPC 上で開発し，高等専門学校の正規の授業で利用した．その結果として，本来は難しいはずの自己克服活動が多く観測されたことから，本システムの有用性が示唆されたと判断している

Experimental Evaluation of Learning Effect of Problem-Simplification for Self-overcoming of Failures: The Case of Music Rhythm Exercises

音楽リズム演奏課題を対象とした演習システムのために設計・開発した単純化方略による誤り克服支援機能の有効性を，この支援機能を用いた演習を受ける実験群と支援機能を用いない演習を受ける統制群を設け，実験的に調べたので報告する

A chloride capturing system: Via proton-induced structure transformation between opened- and closed-forms of dodecavanadates

Chloride-incorporated dodecavanadates show two distinct structures of the monoprotonated-form [HV12O32(Cl)]4- (closed-V12) with a spherical closed-structure and the opened-form [V12O32(Cl)]5- (opened-V12). The reaction of closed-V12 with a stoichiometric amount of ethylenediamine drives the structure transformation reaction to opened-V12, quantitatively. From time dependent observations of 51V NMR, a tube-type intermediate [V12O32(Cl)]5- (tube-V12) was observed in the transformation process. Isolation of the intermediate was achieved by the deprotonation reaction of closed-V12 with diethylamine, and the structure transformation was confirmed by using the isolated intermediate. The reverse transformation from opened-V12 to closed-V12 was also achieved by addition of trifluoroacetic acid. The geometrical difference between closed-V12 and opened-V12 is reflected in the reactivity difference to the external reagents, and this was demonstrated by examining the chloride removal reaction by using a silver cation. The incorporated chloride was preserved in the closed-V12 cage even in the presence of a silver cation. In contrast, the chloride in opened-V12 was removed as AgCl by the silver cation. In addition, by the reaction of chloride-free opened-V12 with a quantitative amount of {Et4N}Cl retrieved opened-V12, showing the capability of opened-V12 to recapture a guest chloride in the cavity. This transformation between two isomeric dodecavanadate structures is regarded as the movement of a molecular mitt to catch a ball and secure it. © 2016 The Royal Society of Chemistry.Embargo Period 12 month