Finding the Most Catalytically Active Platinum Clusters With Low Atomicity

On a subnanometer scale, an only one‐atom difference in a metal cluster may cause significant transitions in the catalytic activity due to the electronic and geometric configurations. We now report the atomicity‐specific catalytic activity of platinum clusters with significantly small atomicity, especially below 20. The atomic coordination structure is completely different from that of the larger face‐centered cubic (fcc) nanocrystals. Here, an electrochemical study on such small clusters, in which the atomicity ranged between 12 and 20, revealed Pt₁₉ as the most catalytically active species. In combination with a theoretical study, a common structure that leads to a high catalytic performance is proposed.     

The Source of “Fairy Rings”: 2‐Azahypoxanthine and its Metabolite Found in a Novel Purine Metabolic Pathway in Plants

Rings or arcs of fungus‐stimulated plant growth occur worldwide; these are commonly referred to as “fairy rings”. In 2010, we discovered 2‐azahypoxanthine (AHX), a compound responsible for the fairy‐ring phenomenon caused by fungus; AHX stimulated the growth of all the plants tested. Herein, we reveal the isolation and structure determination of a common metabolite of AHX in plants, 2‐aza‐8‐oxohypoxanthine (AOH). AHX is chemically synthesized from 5‐aminoimidazole‐4‐carboxamide (AICA), and AHX can be converted into AOH by xanthine oxidase. AICA is one of the members of the purine metabolic pathway in animals, plants, and microorganisms. However, further metabolism of AICA remains elusive. Based on these results and facts, we hypothesized that plants themselves produce AHX and AOH through a pathway similar to the chemical synthesis. Herein, we demonstrate the existence of endogenous AHX and AOH and a novel purine pathway to produce them in plants.     

Coherent-phonon-assisted excitation transfer via optical near fields in dilute magnetic semiconductor nanostructures

Optical near-field (ONF) phenomena observed in nanoscale systems have been applied to nano-fabrication and nano-photoelectronic devices for the last decade. Excitation transfer (ET) is an elementary process caused by ONF interaction localized at the nanoscale in real space. Recently, we have observed spin-dependent ET controlled by an external field and discovered the sign of assistance of phonons. In this work, we elucidate that the assistance of coherent phonons in ET originates from two types of mechanism: energy resonance between exciton levels renormalized by phonon effects and enhancement by phase matching between coherent oscillation of populations and phonon oscillation. This study will stimulate the development of the application of ET via a ONF to nano-photoelectronic devices.     

Membrane Preparation of Polysulfonic Acid Complexes by Layer-by-Layer Adsorption

Summary: The water-insoluble, thermostable and homogeneous polymer complex membrane formation of polysulfonic acids was examined by modifying the preparation conditions of the layer-by-layer adsorption method of the acid and base polymers. The complexation of poly(4-styrenesulfonic acid) in the 0.15 unit mM solution with poly(allylamine) gave a polymer complex membrane on a gold substrate in which one polymer layer was formed with a thickness of 1 nm. Properties including the proton conductivity of the membrane suggested possible applications of the polymer complex membrane.