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Aluminum Electroplating on AZ31 Magnesium Alloy with Acetic Anhydride Pretreatment

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 1996-2006页

作者： Zelei Zhang Atsushi Kitada Kazuhiro Fukami Kuniaki murase Department of Materials Science and Engineering Kyoto UniversityKyoto 606-8501Japan Department of Chemical System Engineering The University of TokyoTokyo 113-8656Japan

Magnesium(Mg)alloys for metal electroplating require a surface pretreatment,i.e.,the removal of the spontaneously oxidized surface layer(MgO,Mg(OH)_(2),andMgCO_(3)).However,the use of highly toxic and/or corrosive acids in conventional pretreatment processes has become an *** this study,a facile and less toxic pretreatment is demonstrated and applied in aluminum(Al)*** immersion of the AZ31 Mg alloy into acetic anhydride(Ac_(2)O)removed the spontaneously oxidized surface layer and formed a thin but stable magnesium acetate(Mg(OAc)_(2))layer that protects the metal substrate from further *** Al electroplating bath is a concentrated diglyme(G2)-AlCl_(3)organic solution that can readily dissolve Mg(OAc)_(2)to enable direct plating onto a metal *** as-deposited Al layer has a compact and crack-free morphology that improves the corrosion resistance and hardness(2.7 GPa).Owing to the lack of an interfacial oxidized layer,heat treatment led to the successful diff usion of Mg and Al atoms,which increased the hardness to 4.4 *** Ac_(2)O pretreatment of Mg alloys enables the successful Al electroplating and subsequent heat treatment.

关键词： Magnesium alloy Surface modifi cation Electrodeposition Hardness Corrosion resistance

Information for Disaster Preparedness: A Social Network Approach to Rainwater Harvesting Technology Dissemination

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International Journal of Disaster Risk Science 2014年第2期5卷 95-109页

作者： Subhajyoti Samaddar Makoto murase Norio Okada Disaster Prevention Research Institute Kyoto UniversityGokashoUjiKyoto 6110011Japan Institute for Sky Water Harvesting 1201-2 FukasawaGotemba CityShizuoka Prefecture 4120023Japan Institute for the Research of Disaster Area Reconstruction Kwansei Gakuin UniversityHyogo 6628501Japan

Rainwater harvesting technology is considered an innovative and effective mechanism for reducing drinking water risks due to arsenic contamination and water salinity in coastal Bangladesh. However, adoption of such tanks remains elusive. Most studies on disaster risk communication are predominantly based on individuallevel cognitive modeling approaches, which fail to address the role of social groups, human relations, and other collective social factors in the dissemination process of disaster preventive measures. From the viewpoint of social implementation, community adoption of unfamiliar technology for disaster risk mitigation and preparedness requires another approach. Given the challenge to promote rainwater harvesting technology in the study area of coastal Bangladesh, this study examines the role of various social networks including cohesive groups(friends), structural equivalent groups(individuals who have the same position in society), and spatial groups(neighbors) in three information sharing and processing activities—hearing, observation, and discussion. Results show that those individuals who have similar cohesive affiliations tend to become hearing and discussion partners. Cohesive groups share a learning opportunity and are bounded by normative constraints in terms of direct and intimate social *** groups facilitate observation, which provides visual learning. Structurally equivalent groups are not relevant in adoption dissemination;therefore competition or similar social environment did not influence the rainwater tank dissemination activities.

关键词： disaster harvesting tank

Annealing,solvation,and mirror-plating effects in phosphonium chloroaluminate ionic liquids

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Nano Research 2023年第2期16卷 3348-3357页

The physicochemical properties of a specific ionic liquid(IL)are naturally considered to be constant at a given ***,a series of eutectic melts of trihexyl(tetradecyl)phosphonium chloride([P6,6,6,14]Cl)with aluminum chloride(AlCl3)is an *** viscosity of Al_(2)Cl_(7)−-dominated[P6,6,6,14]Cl–AlCl_(3)ILs(i.e.,AlCl_(3)mole fraction x=0.60–0.67)gradually increased as a function of *** also influenced the ultraviolet–visible spectra,nuclear magnetic resonance spectra,and the glass transition temperature of the *** annealing-induced variations in physicochemical properties were not observed in the AlCl4−-and Cl−-dominated *** particular,the ionic conductivities of the ILs(x=0.60–0.67)were strongly decoupled from their viscosities during *** initio calculations revealed the bending of the long tetradecyl chains in[P6,6,6,14]+coupled with Al_(2)Cl_(7)−,while neither Cl−nor AlCl_(4)−caused *** general,[P6,6,6,14]+-based ILs are recognized as sponge-like structures that consist of nano-scale polar and non-polar *** propose a gradual structurization process in Al_(2)Cl_(7)−-dominated ILs to account for their unusual physicochemical ***,the addition of tetradecane,solvated in the non-polar domains of the ILs,substantially reduced the viscosity of the structured IL with x=*** Al electroplating is possible without a brightener,using the x=0.67 ILs,regardless of annealing or the admixture of tetradecane.

关键词： ionic liquid physicochemical property ab initio calculation electrodeposition

Analysis of antioxidant prenylflavonoids in different parts of Macaranga tanarius,the plant origin of Okinawan propolis

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Asian Pacific Journal of Tropical Medicine 2014年第1期7卷 16-20页

作者： Shigenori Kumazawa Masayo murase Noboru Momose Syuichi Fukumoto Department of Food and Nutritional Sciences University of Shizuoka52-1 YadaSuruga-kuShizuoka 422-8526.Japan Pokka Sapporo Food and Beverage 45-2 JuunisoKumanoshouKitanagoya-cityAichi 481-8515Japan

Objective:To analyze the antioxidant prenylilavonoids in different parts of Macaranga tanarius(***)(Euphorbiaceae)including the leaf,petiole,stem,leaflet,flower and fruit(only in female plant),and to evaluate their antioxidant ***:Methanol extracts of each part of *** were prepared and five prenylilavonoids in them were quantitatively analyzed using *** fruits from female plant were further separated into seed,pericarp,and glandular *** the quantitative analyses of prenylflavonoids in each part of ***,antioxidant activity of the extracts was evaluated by 2,2-diphenyl-l-picryI-hydrazyl(DPPH)radical scavenging ***:The leaf of *** contained two prenylflavonoids as main components in both male and female *** flowers(male and female)contained five kinds of *** the petiole,stem and leaflet of both male and female plants,the prenylflavonoids were not delected or their amounts were very *** kinds of prenylflavonoids were detected in the seed,pericarp and glandular trichome of female *** particular,the glandular trichome had the highest level of total prenylflavonoids(235 mg/g of fresh plant).DPPH radical scavenging activity of all parts was more than 30%.Conclusions:We found that different parts of *** contained antioxidant *** particular,not only the glandular trichome but also the leaf contained prenylflavonoids,which indicated that *** may be developed as a functional plant,because the leaves of this plant can be easily collected.

关键词： Macaranga tanarius Antioxidant Prenylflavonoid Propolis Plant origin Okinawa

Methods for Estimating Specific Loss Power in Magnetic Hyperthermia Revisited

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Open Journal of Applied Sciences 2016年第12期6卷 815-825页

作者： Kenya murase Department of Medical Physics and Engineering Division of Medical Technology and Science Faculty of Health Science Graduate School of Medicine Osaka University Osaka Japan

Our purpose in this study was to present three methods for estimating specific loss power (SLP) in magnetic hyperthermia with use of an alternating magnetic field (AMF) and magnetic nanoparticles (MNPs) and to compare the SLP values estimated by the three methods using simulation studies under various diameters of MNPs (D), amplitudes (H0) and frequencies of AMF (f). In the first method, the SLP was calculated by solving the magnetization relaxation equation of Shliomis numerically (SLP1). In the second method, the SLP was obtained by solving Shliomis’ relaxation equation using the complex susceptibility (SLP2). The third method was based on Rosensweig’s model (SLP3). The SLP3 value changed largely depending on the magnetic field strength (H) in the Langevin parameter (§) and it became maximum (SLP3max) and minimum (SLP3min) when H was 0 and ±H0, respectively. The relative difference between SLP1 and SLP2 was the largest and increased with increasing D and H0, whereas that between SLP1 and was the smallest and was almost constant regardless of D and H0, suggesting that H in ξ should be taken as H0 in estimating the SLP using Rosensweig’s model. In conclusion, this study will be useful for optimizing the parameters of AMF in magnetic hyperthermia and for the optimal design of MNPs for magnetic hyperthermia.

关键词： Magnetic Hyperthermia Magnetic Nanoparticle Specific Loss Power Alternating Magnetic Field Magnetization Relaxation

A Simulation Study on the Specific Loss Power in Magnetic Hyperthermia in the Presence of a Static Magnetic Field

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Open Journal of Applied Sciences 2016年第12期6卷 839-851页

作者： Kenya murase Department of Medical Physics and Engineering Division of Medical Technology and Science Faculty of Health Science Graduate School of Medicine Osaka University Osaka Japan

Our purpose in this study was to present a method for estimating the specific loss power (SLP) in magnetic hyperthermia in the presence of an external static magnetic field (SMF) and to investigate the SLP values estimated by this method under various diameters (D) of magnetic nanoparticles (MNPs) and amplitudes (H0) and frequencies (f) of an alternating magnetic field (AMF). In our method, the SLP was calculated by solving the magnetization relaxation equation of Shliomis numerically, in which the magnetic field strength at time t (H(t)) was assumed to be given by , with Hs being the strength of the SMF. We also investigated the SLP values in the case when the SMF with a field-free point (FFP) generated by two solenoid coils was used. The SLP value in the quasi steady state (SLPqss) decreased with increasing Hs. The plot of the SLPqss values against the position from the FFP became narrow as the gradient strength of the SMF (Gs) increased. Conversely, it became broad as Gs decreased. These results suggest that the temperature rise and the area of local heating in magnetic hyperthermia can be controlled by varying the Hs and Gs values, respectively. In conclusion, our method will be useful for estimating the SLP in the presence of both the AMF and SMF and for designing an effective local heating system for magnetic hyperthermia in order to reduce the risk of overheating surrounding healthy tissues.

关键词： Magnetic Hyperthermia Magnetic Nanoparticle Specific Loss Power Alternating Magnetic Field Static Magnetic Field Magnetization Relaxation Field-Free Point

Numerical Analysis of the Magnetization Behavior in Magnetic Resonance Imaging in the Presence of Multiple Chemical Exchange Pools

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Open Journal of Applied Sciences 2017年第1期7卷 1-14页

作者： Kenya murase Department of Medical Physics and Engineering Division of Medical Technology and Science Faculty of Health Science Graduate School of Medicine Osaka University Osaka Japan

The purpose of this study was to demonstrate a simple and fast method for solving the time-dependent Bloch-McConnell equations describing the behavior of magnetization in magnetic resonance imaging (MRI) in the presence of multiple chemical exchange pools. First, the time-dependent Bloch- McConnell equations were reduced to a homogeneous linear differential equation, and then a simple equation was derived to solve it using a matrix operation and Kronecker tensor product. From these solutions, the longitudinal relaxation rate (R1ρ) and transverse relaxation rate in the rotating frame (R2ρ) and Z-spectra were obtained. As illustrative examples, the numerical solutions for linear and star-type three-pool chemical exchange models and linear, star- type, and kite-type four-pool chemical exchange models were presented. The effects of saturation time (ST) and radiofrequency irradiation power (ω1) on the chemical exchange saturation transfer (CEST) effect in these models were also investigated. Although R1ρ and R2ρ were not affected by the ST, the CEST effect observed in the Z-spectra increased and saturated with increasing ST. When ω1 was varied, the CEST effect increased with increasing ω1 in R1ρ, R2ρ, and Z-spectra. When ω1 was large, however, the spillover effect due to the direct saturation of bulk water protons also increased, suggesting that these parameters must be determined in consideration of both the CEST and spillover effects. Our method will be useful for analyzing the complex CEST contrast mechanism and for investigating the optimal conditions for CEST MRI in the presence of multiple chemical exchange pools.

关键词： Bloch-McConnell Equations Multiple Chemical Exchange Pools Chemical Exchange Saturation Transfer (CEST) Magnetic Resonance Imaging (MRI) Amide Proton Transfer (APT) MRI Numerical Analysis

Lock-in-Amplifier Model for Analyzing the Behavior of Signal Harmonics in Magnetic Particle Imaging

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Open Journal of Applied Sciences 2018年第5期8卷 170-183页

作者： Kenya murase Kazuki Shimada Department of Medical Physics and Engineering Division of Medical Technology and Science Faculty of Health Science Graduate School of Medicine Osaka University Suita Japan Global Center for Medical Engineering and Informatics Osaka University Suita Japan

The purpose of this study was to present a lock-in-amplifier model for analyzing the behavior of signal harmonics in magnetic particle imaging (MPI) and some simulation results based on this model. In the lock-in-amplifier model, the signal induced by magnetic nanoparticles (MNPs) in a receiving coil was multiplied with a reference signal, and was then fed through a low-pass filter to extract the DC component of the signal (output signal). The MPI signal was defined as the mean of the absolute value of the output signal. The magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively, and the strength of the selection magnetic field (SMF) in MPI was assumed to be given by the product of the gradient strength of the SMF and the distance from the field-free region (x). In addition, Gaussian noise was added to the signal induced by MNPs using normally-distributed random numbers. The relationships between the MPI signal and x were calculated for the odd- and even-numbered harmonics and were investigated for various time constants of the low-pass filter used in the lock-in amplifier and particle sizes and their distributions of MNPs. We found that the behavior of the MPI signal largely depended on the time constant of the low-pass filter and the particle size of MNPs. This lock-in-amplifier model will be useful for better understanding, optimizing, and developing MPI, and for designing MNPs appropriate for MPI.

关键词： Magnetic Particle Imaging (MPI) Lock-in-Amplifier Model Signal Harmonics Magnetic Nanoparticles (MNPs)

Effect of Signal Filtering on Image Quality of Projection-Based Magnetic Particle Imaging

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Open Journal of Medical Imaging 2017年第2期7卷 43-55页

作者： Kazuki Shimada Kenya murase Department of Medical Physics and Engineering Division of Medical Technology and Science Faculty of Health Science Graduate School of Medicine Osaka University Osaka Japan

Purpose: Magnetic particle imaging (MPI) allows for imaging of the spatial distribution of magnetic nanoparticles (MNPs) in positive contrast, with high sensitivity, high spatial resolution, and high imaging speed. It is necessary to increase the signal-to-noise ratio to enhance the reliability of MPI. The purpose of this study was to investigate the effect of signal filtering on the image quality and quantitativity in projection-based MPI using phantoms. Materials and Methods: We fabricated two kinds of phantom (cylindrical tube phantom with a diameter of 6 mm and A-shaped phantom) and evaluated the effect of signal filtering in terms of root-mean-square (RMS) granularity and the correlation coefficient between iron concentrations of MNPs and average MPI values for four filter modes (THRU, BPF, BEF, and LPF). In the THRU mode, the signal input was output without passing through the filter. In the BPF mode, only the third-harmonic signal was passed using a band-pass filter (central frequency: 1200 Hz, band width: 1/3 octave). In the BEF mode, the first-harmonic signal was eliminated using a band-elimination filter (central frequency: 400 Hz, band width: 1/3 octave). In the LPF mode, only the signal with a frequency less than the third-harmonic frequency was passed using a low-pass filter (cut-off frequency: 1200 Hz, -24 ± 2 dB/octave). The RMS granularity was obtained by calculating standard deviations of the pixel values in the MPI image without MNPs, whereas average MPI values were obtained by drawing a circular region of interest with a diameter of 6 mm on the MPI image of the cylindrical tube phantom. Results: When using the filtered back-projection (FBP) method with a ramp filter for image reconstruction, the RMS granularity and correlation coefficient decreased in the order of THRU, BPF, BEF, and LPF. In the BPF mode, however, some artifacts were observed. When using the maximum likelihood-expectation maximization (ML-EM) algorithm with an iteration number of

关键词： Magnetic Particle Imaging (MPI) Magnetic Nanoparticles (MNPs) Signal Filtering Image Quality Root-Mean-Square (RMS) Granularity