Shunsuke Yagi

Rechargeable Mg batteries (RMBs) are promising energy-storage systems due to the high volumetric capacity of Mg metal (3833 mAh cm-3), its low standard electrode potential among metals usable in air (-2.37 V vs. SHE), its natural abundance, low cost, and operational safety. However, the role of electrode architecture in determining electrochemical performance has not yet been systematically investigated. Herein, α-KxMnO2 composite positive electrodes with an identical active mass loading (0.5 mg cm-2) were roll-pressed to tailor the electrode porosity, and their structural and electrochemical properties were evaluated in rechargeable Mg pouch cells. Moderate roll-pressing (35–60 % thickness reduction) significantly improved the initial discharge capacity (~102 mAh g-1) by enhancing particle packing and reducing pore volume, resulting in more efficient active material utilization than that of the nonpressed electrode. In contrast, excessive roll-pressing (80% thickness reduction) resulted in a lower initial discharge capacity (~89 mAh g-1) and higher overpotential because the electrolyte was expelled and the Mg2+ transport was hindered. Therefore, moderate electrode densification improves particle-to-particle contact without severely hindering Mg2+ transport. This study provides practical design guidelines for optimizing composite positive electrodes by increasing particle-to-particle contact while maintaining sufficient electronic conductivity and ionic transport, thereby improving electrochemical performance.

Electrochemical reduction of CO₂ represents a promising strategy for converting CO₂ into value‐added chemical products. Currently, significant efforts have been devoted to developing more efficient Bi‐based catalysts to reduce CO₂ to formate. However, the role of precursor defects in directing the electrochemical reconstruction of Bi‐based catalysts is yet to be thoroughly investigated. Herein, a strong alkali‐induced strategy, coupled with electrochemical reduction for controllable morphology and defect engineering to achieve Bi₂O₃ reconstruction with oxygen vacancies (O_v‐Bi₂O₃) into defect‐rich Bi nanoflowers (Bi (O_v‐Bi₂O₃)) featuring small‐angle grain boundaries, is reported. Over a wide potential range (from −0.87 to −1.17 V vs. reversible hydrogen electrode [RHE]) in an H‐type cell, Bi (O_v‐Bi₂O₃) exhibits a high Faradaic efficiency of formate (>95%). Moreover, it displays a high current density (−340 mA cm⁻²) at −1.08 V versus RHE and a formate production rate of 6.09 mmol h⁻¹ cm⁻² in a flow cell, thus highlighting its potential for industrial applications. In situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy offers detailed insights into the reaction mechanism, verifying that formate formation predominantly occurs through the *OCHO intermediate. This study reveals the role of precursor‐derived defects in catalytic properties, clarifying mechanisms and guiding performance optimization.

Heparin-induced thrombocytopenia (HIT) is a serious side effect that occurs in patients undergoing heparin therapy. The known risk factor is the presence of antibodies created against platelet factor 4 and heparin complexes (PF4/heparin) in the blood, which activate platelet Fc receptors (FcγRIIA). Although immunoassays have been developed for HIT diagnosis, their specificity remains low (∼50%) due to the binding of nonpathogenic antibodies to the same antigen (PF4/heparin). As a result, a lack of rapid, highly sensitive, and selective diagnostic tests poses challenges for HIT treatment. In this study, we used monoclonal HIT-like KKO antibodies as a model and demonstrated a rapid biosensor based on quartz crystal microbalance (QCM) that effectively distinguishes the pathogenic (KKO) from nonpathogenic (RTO) antibodies within 10 min. Based on our key finding, KKO and RTO present clear binding affinity differences against FcγRIIA: RTO binds to FcγRIIA while KKO can bind to FcγRIIA only in the presence of PF4/heparin. The determined negative zeta potentials of proteins confirmed that the observed affinity differences toward FcγRIIA result from specific binding rather than nonselective electrostatic interactions. This highlights the potential use of FcγRIIA as an antigen instead of traditional PF4/heparin complexes. Although only a monoclonal HIT-like antibody was tested, the use of FcγRIIA to distinguish the binding patterns of KKO and RTO could be extended to the detection of human HIT antibodies.

The stimuli-responsive phase transition in a synthetic model of marginally stable proteins, composed of poly(N-isopropylacrylamide) with incorporated redox-responsive sites, is elucidated.