Enhancement of sonochemical reaction of terephthalate ion by superposition of ultrasonic fields of various frequencies

The ultrasonic reactor with dual frequency was used and the effect of frequency on the fluorescence intensity of terephthalate ion was experimentally investigated in the frequency range from 176 to 635 kHz. The sonochemical reaction fields were visualized by using sonochemical luminescence of luminol solution. Compared with the fluorescence intensity of terephthalate ion for single frequency, the fluorescence intensity for dual frequency increased. The fluorescence intensity ratio of dual frequency to single frequency had maximum value when the frequency of transducer attached at the bottom wall was comparable in magnitude to that at the side wall. In the case of dual frequency, the sonochemical reaction fields became more extensive in the reactor and more intensive around the center of the reactor.     

Biodegradable Polyurethanes from Plant Components

Abstract

Polyurethane (PU) sheets and foams having plant components in their network were prepared by using the following procedure. Polyethylene glycol (PEG) was mixed with one of the following; molasses, lignin, woodmeal, or coffee grounds. The mixture obtained was reacted with diphenylmethane diisocyanate (MDI) at room temperature, and precured PUs were prepared. The precured PUs were heat-pressed and PU sheets were obtained. In order to make PU foam, the above mixture was reacted with MDI after the addition of plasticizer, surfactant (silicone oil), catalyst (di-n-butyltin dilaurate), and droplets of water under vigorous stirring. The glass transition temperature, tensile and compression strengths, and Young's modulus of the PU sheets and foams increased with an increasing amount of plant components. This suggests that saccharide and lignin residues act as hard segments in PUs. It was found that the PUs obtained were biodegradable in soil. The rate of biodegradation of the PUs derived from molasses and coffee grounds was between that of cryptomeria (Cryptomeria japonica) and beech (Fagus sieboldi).     

Neutron Halo Structure at the Limit of Stability Probed by Breakup Reactions

Atomic nuclei along the neutron drip line are investigated experimentally by breakup reactions of the rare isotope beams. Such exotic nuclei often show the neutron halo structure, which is the main focus of this paper. Characteristic features of the Coulomb and nuclear breakup at intermediate to high incident energies are described. Then, recent experimental results on halo nuclei, mainly on ³¹Ne, obtained at the new-generation RI-beam facility, RIBF (RI Beam factory) at RIKEN, are presented. Perspectives for the breakup experiments using the new facility SAMURAI at RIBF ara also discussed.     

原位Raman光谱揭示中性条件下硫化钼结构变化对其电催化析氢反应的促进作用（英文）

硫化钼是析氢反应(HER)有前途的电催化剂.S-或Mo物种均被认为是形成吸附氢触发HER反应的活性位,但Mo中心和S配体间相互作用的本质仍不清楚.另外,采用中性的水作为质子源用于产氢,来开发低成本的水裂解催化剂体系为研究者高度关注,但人们很少研究中性水条件下HER反应的机理.本文采用原位电化学Raman光谱对所合成的硫化钼中Mo–Mo和S–S物种在中性条件下的结构变化进行了监测.结果显示,归属于端位S–S物种的谱带随着和Mo–S振动谱带频率而同步变化,表明Mo–Mo键与端位S–S键起着协同作用,从而有利于氢气的生成.这可能是通过三核物种的内部重组而确认的.本文所揭示的HER反应中金属-配体相互作用的本质与作用表明了一个不同的反应机理,而以往的机理认为,S或Mo活性位独立起作用而促进HER反应的进行.     

Synthesis,Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems

A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro‐Diels–Alder reaction of bicyclo[2.2.2]octadiene‐fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time‐dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π‐molecular orbitals.     

Neutrino Reactions with Deuteron in Core-Collapse Supernova

We have investigated the neutrino reactions via deuteron in the surface region of the supernova core. We evaluate the electron capture on deuterons and the neutrino emission from nucleon-nucleon scattering through the deuteron formation and found an important role of neutrino reactions with deuteron.