Carbon Nitride Loaded with an Ultrafine,Monodisperse, Metallic Platinum-Cluster Cocatalyst for the Photocatalytic Hydrogen-Evolution Reaction

For the realization of a next-generation energy society, further improvement in the activity of water-splitting photocatalysts is essential. Platinum (Pt) is predicted to be the most effective cocatalyst for hydrogen evolution from water. However, when the number of active sites is increased by decreasing the particle size, the Pt cocatalyst is easily oxidized and thereby loses its activity. In this study, a method to load ultrafine, monodisperse, metallic Pt nanoclusters (NCs) on graphitic carbon nitride is developed, which is a promising visible-light-driven photocatalyst. In this photocatalyst, a part of the surface of the Pt NCs is protected by sulfur atoms, preventing oxidation. Consequently, the hydrogen-evolution activity per loading weight of Pt cocatalyst is significantly improved, 53 times, compared with that of a Pt-cocatalyst loaded photocatalyst by the conventional method. The developed method is also effective to enhance the overall water-splitting activity of other advanced photocatalysts such as SrTiO₃ and BaLa₄Ti₄O₁₅.     

Scintillator-oriented near-infrared emitting Cs4SrI6:Yb2+, Sm2+ single crystals via sensitization strategy

In this study, a new Cs₄SrI₆:Yb²⁺,Sm²⁺ near-infrared (NIR) emitting scintillator was developed using sensitization strategy. It was found that Yb²⁺ sensitization significantly enhances the NIR radioluminescence (RL) of Sm²⁺, providing a new approach of designing highly emissive sensitized NIR scintillators. By studying the optical spectra and decay kinetics of Cs₄SrI₆:Yb²⁺,Sm²⁺, it was revealed that the energy transfer pathways involve both radiative and nonradiative processes. The gamma spectroscopy performance of Cs₄SrI₆:Yb²⁺,Sm²⁺ single crystals was studied by using the high-quantum-efficiency avalanche photodiode (APD) as the readout. Our results highlight the importance of using sensitization strategy of achieving NIR emitting scintillators and demonstrate the significant potential for radiation detection applications.     

S-Denitrosylase-Like Activity of Cyclic Diselenides Conjugated with Xaa-His Dipeptide: Role of Proline Spacer as a Key Activity Booster

This study developed dipeptide-conjugated 1,2-diselenan-4-amine ( 1 ), i. e., 1 -Xaa-His, as a new class of S-denitrosylase mimic. The synthesized compounds, especially 1 -Pro-His, remarkably promoted S-denitrosylation of nitrosothiols (RSNO) via a catalytic cycle involving the reversible redox reaction between the diselenide and its corresponding diselenol ([SeH,SeH]) form with coexisting reductant thiols (R′SH), during which the [SeH,SeH] form as a key reactive species reduces RSNO to the corresponding thiol (RSH). Structural analyses of 1 -Pro-His suggested that the peptide backbone of [SeH,SeH] is rigidly bent to form a γ-turn, possibly including an NH⋅⋅⋅Se hydrogen bond between the imidazole ring of His and selenol group, thus stabilizing the [SeH,SeH] form thermodynamically, and dramatically enhancing the catalytic activity. Furthermore, the synthetic compounds were found to prohibit S-nitrosylation-induced protein misfolding in the presence of RSNO, eventually implying their potential as a drug seed for misfolding diseases caused by the dysregulation of the S-denitrosylation system.     

[Fe]-Hydrogenase,Cofactor Biosynthesis and Engineering

[Fe]-hydrogenase catalyzes the heterolytic cleavage of H₂ and reversible hydride transfer to methenyl-tetrahydromethanopterin. The iron-guanylylpyridinol (FeGP) cofactor is the prosthetic group of this enzyme, in which mononuclear Fe(II) is ligated with a pyridinol and two CO ligands. The pyridinol ligand fixes the iron by an acyl carbon and a pyridinol nitrogen. Biosynthetic proteins for this cofactor are encoded in the hmd co-occurring (hcg) genes. The function of HcgB, HcgC, HcgD, HcgE, and HcgF was studied by using structure-to-function analysis, which is based on the crystal structure of the proteins and subsequent enzyme assays. Recently, we reported the catalytic properties of HcgA and HcgG, novel radical S-adenosyl methionine enzymes, by using an in vitro biosynthesis assay. Here, we review the properties of [Fe]-hydrogenase and the FeGP cofactor, and the biosynthesis of the FeGP cofactor. Finally, we discuss the expected engineering of [Fe]-hydrogenase and the FeGP cofactor.     

A Transient Pseudo-Capacitor Using a Bioderived Ionic Liquid with Na Ions

A pseudo-capacitor with transient behavior is applied in implantable, disposable, and bioresorbable devices, incorporating an Na ion-doped bioderived ionic liquid, molybdenum trioxide (MoO₃)-covered molybdenum foil, and silk sheet as the electrolyte, electrode, and separator, respectively. Sodium lactate is dissolved in choline lactate as a source of Na ions. The Experimental results reveal that the Na ions are intercalated into the van der Waals gaps in MoO₃, and the pseudo-capacitor shows an areal capacitance (1.5 mF cm⁻²) that is three times larger than that without the Na ion. The fast ion diffusion of the electrolyte and the low resistance of the MoO₃ and Mo interface result in an equivalent series resistance of 96 Ω. A cycle test indicates that the pseudo-capacitor exhibited a high capacitance retention of 82.8% after 10 000 cycles. The transient behavior is confirmed by the dissolution of the pseudo-capacitor into phosphate-buffered saline solution after 101 days. Potential applications of transient pseudo-capacitors include electronics without the need for device retrieval after use, including smart agriculture, implantable, and wearable devices.     

Analysis of negative phototaxis in the pill bug (Armadillidium vulgare) using omnidirectional servosphere

Artificial Life and Robotics - In recent years, automated systems and robots have been implemented in biological behavioral experiments to understand taxis. In this study, we propose a servosphere...