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SSRN 2024年

作者： Lee, Haeyeon Go, Su Yong Kim, Chae Yun Kim, Eun Joong Kang, Chung Mu Chung, Taek Dong Department of Chemistry Seoul National University Seoul08826 Korea Republic of Program in Nano Science and Technology Graduate School of Convergence Science and Technology Seoul National University Suwon16229 Korea Republic of Advanced Institute of Convergence Technology Suwon16229 Korea Republic of

Indium tin oxide (ITO) is a widely used electrode material in electrochemical biosensors owing to its beneficial characteristics such as transparency and chemical inertness. The exceptionally sluggish kinetics of heterogeneous electron transfer in ITO provides an exceptionally low background current, making electron mediators essential for electrochemical sensors. However, the chemical modification of ITO with molecular mediators is still challenging. Few straightforward and credible methods are available to obtain sufficiently thin mediator films firmly anchored on the ITO without losing its inherent benefits, including low background current and transparency. This study demonstrated the anodic electrografting of three osmium complexes, which allowed the formation of molecular mediator monolayers on ITO. The densely packed monolayer of osmium complexes retained their reversible redox processes over hundreds of potential cycles. We confirmed electron mediation by the modified electrodes for aminophenol oxidation, suggesting a simple protocol for developing ITO-based biosensors functionalized with molecular mediators. © 2024, The Authors. All rights reserved.

关键词： Tin oxides

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Improvement of corrosion resistance and heat dissipation of Mg-6%Al-4%Ca alloy by the addition of Mn, Mm, and the surface treatment

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Keikinzoku/Journal of Japan Institute of Light Metals 2023年第12期73卷 646-650页

作者： Ito, Mizuki Kondo, Natsuki Kirimoto, Yuichi Tsukeda, Tadayoshi Aida, Tetsuo Tabata, Hironobu Kurihara, Hideki Suzuki, Mayumi Program of Materials Science and Engineering Studies in Science and Engineering Graduate School of Science and Engineering University of Toyama 3190 Gofuku Toyama-shi Toyama930-8555 Japan School of Sustainable Design Materials and Engineering University of Toyama Toyama Toyama-shi Japan Department of Nano and Functional Material Science Graduate School of Science and Engineering for Education University of Toyama Toyama Toyama-shi Japan Faculty of Sustainable Design Academic Assembly University of Toyama Toyama Toyama-shi Japan CHUETSU METAL WORKS CO LTD.. Nakaniikawa-gun Toyama Japan Saitama Industrial Technology Center Kawaguchi-shi Saitama Japan Department of Mechanical Systems Engineering Faculty of Engineering Toyama Prefectural University Toyama Imizu-shi Japan

With the recent digitization, electronic equipment housings are required to be thin-walled and have rigidity, heat dissipation, corrosion resistance, and electromagnetic shielding properties. Magnesium alloys are promising materials that satisfy these requirements. Mg-Al alloys have good castability and high strength, but their thermal conductivity decreases. In general, adding alloying elements to magnesium decreases thermal conductivity the effect of aluminum addition is significant. It was found that adding calcium to Mg-Al alloys to form Mg-Al-Ca (AX) alloys results in higher thermal conductivity than that of Mg-Al alloys. However, AX alloys have poor corrosion resistance and require post-treatment such as surface treatment. In this study, AX64, which has high thermal conductivity among the AX series alloys, was used as the basic composition, and corrosion resistance was improved by adding manganese and misch metal, and an attempt was made to improve corrosion resistance and emissivity through surface treatment. The change in thermal conductivity by heat treatment was also investigated. Experimental results showed that the addition of manganese and misch metal improved corrosion resistance and thermal conductivity. Plasma anodization also improved corrosion resistance and emissivity. Heat treatment of these alloys at 400°C improved the thermal conductivity with longer holding time. © 2023 The Japan Institute of Light Metals.

关键词： Corrosion resistance

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Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system

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Review of Scientific Instruments 2024年第3期95卷 033701页

作者： Chung, Pei-Fang Venkatesan, Balaji Su, Chih-Chuan Chang, Jen-Te Cheng, Hsu-Kai Liu, Che-An Yu, Henry Chang, Chia-Seng Guan, Syu-You Chuang, Tien-Ming Institute of Physics Academia Sinica Taipei11529 Taiwan Department of Physics National Taiwan University Taipei10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica National Taiwan University Taipei11529 Taiwan

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10−8 m/sec/√Hz for most frequencies up to 100 Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena. © 2024 Author(s).

关键词： Vibration analysis

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A Facile NMR Method for Pre-MRI Evaluation of Trigger-Responsive T1 Contrast Enhancement

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Small Methods 2024年第10期8卷 e2301603页

作者： Jian, Cheng-Bang Wu, Ying-Yann Lin, Ming-Huang Gao, Hua-De Chen, Chong-Yan Leong, Shwee Khuan Tzou, Der-Lii M. Hwang, Dennis W. Lee, Hsien-Ming Institute of Chemistry Academia Sinica Taipei11529 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei11529 Taiwan Department of Chemistry National Taiwan University Taipei10617 Taiwan Institute of Biomedical Sciences Academia Sinica Taipei11529 Taiwan Sustainable Chemical Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Yang Ming Chiao Tung University Taipei11529 Taiwan Department of Applied Chemistry National Yang Ming Chiao Tung University Hsinchu30093 Taiwan

There is a growing interest in developing paramagnetic nanoparticles as responsive magnetic resonance imaging (MRI) contrast agents, which feature switchable T1 image contrast of water protons upon biochemical cues for better discerning diseases. However, performing an MRI is pragmatically limited by its cost and availability. Hence, a facile, routine method for measuring the T1 contrast is highly desired in early-stage development. This work presents a single-point inversion recovery (IR) nuclear magnetic resonance (NMR) method that can rapidly evaluate T1 contrast change by employing a single, optimized IR pulse sequence that minimizes water signal for "off-state" nanoparticles and allows for sensitively measuring the signal change with "switch-on" T1 contrast. Using peptide-induced liposomal gadopentetic acid (Gd3+-DTPA) release and redox-sensitive manganese oxide (MnO2) nanoparticles as a demonstration of generality, this method successfully evaluates the T1 shortening of water protons caused by liposomal Gd3+-DTPA release and Mn2+ formation from MnO2 reduction. Furthermore, the NMR measurement is highly correlated to T1-weighted MRI scans, suggesting its feasibility to predict the MRI results at the same field strength. This NMR method can be a low-cost, time-saving alternative for pre-MRI evaluation for a diversity of responsive T1 contrast systems. © 2024 Wiley-VCH GmbH.

关键词： Nuclear magnetic resonance spectroscopy

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Magnetism-induced second-order nonlinear optical responses in multiferroic BiFeO3

arXiv

引用

arXiv 2024年

作者： Prasad, Babu Baijnath Liu, Guan-Fu Guo, Guang-Yu Department of Physics Center for Theoretical Physics National Taiwan University Taipei10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei11529 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan

Nonlinear optical (NLO) responses of noncentrosymmetric nonmagnets have drawn a lot of attention in the past decades because of their significance in materials characterization, green energy and device applications. On the other hand, magnetism not only can break the inversion symmetry in centrosymmetric crystals but also introduce novel NLO phenomena in noncentrosymmetric materials, thus enabling the magnetic field control of light-matter interactions. However, the magnetism-induced NLO responses have rarely been studied so far. In this paper, we first extend the numerical calculation friendly formula by Rashkeev et al. [Phys. Rev. B 57, 3905 (1998)] for second harmonic generation (SHG) in nonmagnetic materials to include magnetic systems and then calculate the magnetism-induced NLO responses of bismuth ferrite (BiFeO3), a multiferroic that exhibits both ferroelectricity and antiferromagnetic (AFM) ordering at room temperature and has a band gap that falls in the visible frequency region. First, we find that the calculated magnetism-induced SHG susceptibilities are large and the SHG intensity is tunable with the reversal of magnetization. In particular, the interference between crystallographic SHG and magnetically induced SHG components results in a strong magnetic contrast of the SHG signal of ∼440% at SHG photon energy of 4.82 eV, thus enabling a magnetic control of the SHG in multiferroic BiFeO3. Also, because of the sensitivity of the SHG signal to the direction of the Néel vector, the SHG can be utilized to detect the reversal of the Néel vector in the AFM materials, which is an important issue for AFM spintronics. Second, the calculated bulk photovoltaic effects (BPVE) in BiFeO3 are also strong, being larger than some well-known NLO compounds such as BaTiO3, GaAs, CdS and CdSe. Finally, we analyse the origins of the prominent features in the NLO response spectra in terms of the calculated quantum geometric quantities. Our interesting findings suggest that th

关键词： Gallium arsenide

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Perspective on the perovskite quantum dots for flexible photovoltaics

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Journal of Energy Chemistry 2021年第11期30卷 505-507,I0011页

作者： Jiabei Yuan Nopporn Rujisamphan Wanli Ma Jianyu Yuan Youyong Li Shuit-Tong Lee Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory of Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhou 215123JiangsuChina Macao Institute of Materials Science and Engineering Macao University of Science and TechnologyTaipa 999078MacaoChina Nanoscience and Nanotechnology Graduate Program Faculty of ScienceKing Mongkut’s University of Technology ThonburiBangkok 10140Thailand

Owing to the ever-increasing charging demand for portable electronics,display devices and wearable electronic textiles,flexible and lightweight solar cells are highly urgent to be ***-generation solution-processable photovoltaic(PV)devices attracted great attentions due to their unique properties of low-cost,lightweight,and large-area printing compatibility with flexible substrates[1].

关键词： printing perovskite compatibility

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Influence of conformational change of chain unit on the intrinsic negative thermal expansion of polymers

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Chinese Chemical Letters 2021年第4期32卷 1515-1518页

作者： Qiangsheng Sun Ke Jin Yuhui Huang Jia Guo Thanyada Rungrotmongkol Phornphimon Maitarad Changchun Wang State Key Laboratory of Molecular Engineering of Polymers and Department of Macromolecular Science Fudan UniversityShanghai 200433.China Biocatalyst and Environmental Biotechnology Research Unit Department of BiochemistryFaculty of Science and Program in Bioinformatics and Computational BiologyGraduate SchoolChulalongkom UniversityBangkok 10330Thailand Research Center of Nano Science and Technology Shanghai UniversityShanghai 200444China

Negative thermal expansion(NTE) behavior has roused wide interest for the control of thermomechanical properties of functional *** NTE behaviors have been found in kinds of compounds,it remains challenging for polymers to achieve intrinsic NTE *** this work,we systematically studied the conformational change of dibenzocyclooctadiene(DBCOD) derivatives between chair(C) and twist-boat(TB) forms based on density-functional theo ry(DFT) calculations,and found clear evidence of the relationship between the structure of DBCOD units and the thermal contraction behavior of the related *** order to obtain the polymer with NTE property,two conditions should be met for the thermal contracting DBCOD related units as follows:(i) the TB conformation can turn into C conformation as the temperature increases,and(ii) the volume of C conformation is smaller than that of TB *** rule should offer a guidance to exploration of the new intrinsic NTE polymers in the future.

关键词： Negative thermal expansion Conformational change Polyarylamides Density-functional theory Dibenzocyclooctadiene

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Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system

arXiv

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arXiv 2023年

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows the atomic scale visualization of surface electronic and magnetic structure of novel quantum materials with high energy resolution. To achieve the optimal performance, low vibration facility is required. Here, we describe the design and the performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stages. The STM system is equipped with a 1K pot cryogenic insert and a 9 Tesla superconducting magnet, capable of continuous SI-STM measurements for 7 days. A field ion microscopy system is installed for in situ STM tip treatment. We present the detailed vibrational noise analysis of the hybrid vibration isolation system and demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopy to investigate the nanoscale quantum phenomena. © 2023, CC BY-NC-ND.

关键词： Superconducting magnets

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Oxygen-Incorporated Lithium-Rich Iron Sulfide Cathodes for Li-Ion Batteries with Boosted Material Stability and Electrochemical Performance

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Chemistry of Materials 2024年第19期36卷 9370-9379页

作者： Hailemariam, Adane G. Syum, Zeru Mamo, Tadios T. Qorbani, Mohammad Hsing, Cheng-Rong Sabbah, Amr Quadir, Shaham Bayikadi, Khasim S. Wu, Heng-Liang Wei, Ching-Ming Chen, Li-Chyong Chen, Kuei-Hsien Institute of Atomic and Molecular Sciences Academia Sinica Taipei10617 Taiwan Sustainable Chemical Science and Technology Taiwan International Graduate Program Academia Sinica Nangang Taipei11529 Taiwan Institute of Chemistry Academia Sinica Nangang Taipei11529 Taiwan Department of Applied Chemistry National Yang-Ming Chiao Tung University Hsinchu30010 Taiwan Department of Chemistry College of Natural Science Dire Dawa University Dire Dawa1362 Ethiopia Center of Atomic Initiative for New Materials National Taiwan University Taipei10617 Taiwan Department of Chemistry National Taiwan University Taipei10617 Taiwan Institute of Physics Academia Sinica Taipei11529 Taiwan Nano Science and Technology Taiwan International Graduate Program Academia Sinica Nangang Taipei11529 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei10617 Taiwan Division of Natural Science Center for General Education Chang Gung University Taoyuan City33302 Taiwan Tabbin Institute for Metallurgical Studies Tabbin Helwan 109 Cairo11421 Egypt GoldenCO80401 United States Department of Chemistry Northwestern University EvanstonIL60208 United States National Synchrotron Radiation Research Center Hsinchu30092 Taiwan Department of Physics National Taiwan University Taipei10617 Taiwan

Affordable and environmentally friendly electrode materials with multielectron redox reactions are imperative for the advancement of next-generation Li-ion batteries. In this context, the Li-rich layered iron sulfide cathode material (i.e., Li2FeS2) stands out as a promising candidate due to its unique multielectron cationic and anionic redox features. However, its practical application is hampered by inherent limitations in terms of poor structural stability and cycling performance. Herein, we conduct a systematic investigation into the impact of anionic substitution, where sulfur is partially replaced with oxygen, on the structural stability, intrinsic conductivity, and electrochemical properties of the Li2FeS2 cathode. First-principle calculations confirm that an optimum amount of oxygen incorporation is beneficial to stabilize the crystal structure and improve Li ion diffusion. Furthermore, cathodes with oxygen incorporation exhibit significant structural stability even when exposed to air for 24 h, demonstrating resistance against moisture. The Li2FeS1.8O0.2 cathode achieves a higher Coulombic efficiency of ∼100%, charge-discharge capacity of 310 mA h g-1 after 100 cycles, and a remarkable capacity recovery of around 94% following rate capability tests spanning 75 cycles. These findings introduce an innovative anion substitution approach for the development of Li-rich layered sulfide cathode materials, effectively mitigating structural deterioration. © 2024 American Chemical Society.

关键词： Cathodes

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Helicity-tunable spin Hall and spin Nernst effects in unconventional chiral fermion semimetals XY (X=Co,Rh;Y=Si,Ge)

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Physical Review B 2022年第16期106卷 165102-165102页

作者： Ting-Yun Hsieh Babu Baijnath Prasad Guang-Yu Guo Department of Physics National Taiwan University Taipei 10617 Taiwan Republic of China Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei 11529 Taiwan Republic of China Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan Republic of China

Transition metal monosilicides CoSi, CoGe, RhSi, and RhGe in the chiral cubic B20 structure (the CoSi family) have recently been found to host unconventional chiral fermions beyond spin-1/2 Weyl fermions, and also to exhibit exotic physical phenomena such as long Fermi arc surface states, gyrotropic magnetic effect, and quantized circular photogalvanic effect. Thus, exploring novel spin-related transports in these unconventional chiral fermion semimetals may open a new door for spintronics and spin caloritronics. In this paper, we study the intrinsic spin Hall effect (SHE) and spin Nernst effect (SNE) in the CoSi family based on ab initio relativistic band structure calculations. First, we find that unlike nonchiral cubic metals, the CoSi family have two independent nonzero spin Hall (Nernst) conductivity tensor elements, namely, σxyz and σxzy (αxyz and αxzy) instead of one element. Furthermore, the SHC (σxyz and σxzy) and helicity of the chiral structure are found to be correlated, thus enabling SHE detection of structural helicity and also chiral fermion chirality. Second, the intrinsic SHE and SNE in some of the CoSi family are large. In particular, the calculated spin Hall conductivity (SHC) of RhGe is as large as −140 (ℏ/e)(S/cm). The calculated spin Nernst conductivity (SNC) of CoGe is also large, being −1.3 (ℏ/e)(A/m K) at room temperature. Due to their semimetallic nature with low electrical conductivity, these topological semimetals may have large spin Hall and spin Nernst angles, being comparable to that of platinum metal. The SHC and SNC of these compounds can also be increased by raising or lowering the chemical potential to, e.g., the topological nodes, via either chemical doping or electrical gating. Our findings thus indicate that transition metal monosilicides of the CoSi family not only would provide a material platform for exploring novel spin transports and exotic phenomena in unconventional chiral fermion semimetals, but also could be promising m

关键词： Electronic structure Spin Hall effect Spin caloritronics Spintronics Semimetals Topological materials First-principles calculations

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