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971.
Satoka Aoyagi Akira Yano Yasutaka Yanagida Eiji Tanihira Akio Tagawa Mitsuo Iimoto 《Chemical physics》2006
This study investigated the control of dissolved oxygen concentration using magnetic forces from gradient magnetic fields near a Nd–Fe–B permanent magnet. Maximum values of magnetic flux density and the product of the magnetic flux density and its gradient were 0.63 T and 44 T2/m, respectively. The magnet was placed under a Petri dish filled with 15 ml of 10% ammonia water. The Petri dish had a copper sheet in the center. Absorbance of tetraamminecopper(II) complex produced by the reaction in oxygen was measured using a spectrophotometer to observe oxygen concentration. Results showed that the magnetic field quantitatively enhanced tetraamminecopper(II) complex production. Moreover, remarkable enhancement of the copper complex production occurred in the magnetic field at less than 2 mm depth. The calculated magnetic force increase near the magnet surface supports this result. These results show that greater enhancement of the reaction rate occurs when the stronger magnetic force acts on oxygen molecules. 相似文献
972.
The crystal structures of 1,3-bis(4-bromophenyl)- and 1,3-di(2-thienyl)azulenes (5 and 6) were elucidated by X-ray analysis. Two aryl groups connect to the azulenyl core with dihedral angles of 34.9-41.6° and the two aryl planes of the groups slant against the azulene ring toward different ways in their crystal structures. It was also found that the azulene rings of 5 and 6 showed a slight out-of-plane deformation in the way that the hydrogen atoms at the 4- and 8-positions are apart from the neighboring aryl ortho-hydrogen atoms to fill in the vacant space made by the slanting aryl planes. 相似文献
973.
974.
Most celluloses are soluble in 8 mass % lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) and/or 8 mass % LiCl/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) with solvent-exchange treatment
from water to DMAc or DMI through acetone. In this study, the residual DMAc or DMI adsorbed on celluloses after the solvent-exchange
and then vacuum-drying at 60 °C for 48 h was determined by UV spectroscopy and elementary analysis. Significant amounts of
DMI or DMAc remain in the solvent-exchanged celluloses even after vacuum drying: about 1.2 mmol/g and 1.0 mmol/g for DMI and
DMAc, respectively. Thus, corrections of molecular-mass parameters of celluloses, which were reported in previous literatures
based on the assumption that no residual amides are present in the solvent-exchanged and then vacuum-dried celluloses, are
needed. 相似文献
975.
Akira Ohnuma Tomohiro Nagata Kenichi Komura Hiromune Ando Hideharu Ishihara Mamoru Koketsu 《Journal of heterocyclic chemistry》2015,52(2):513-517
Various 2H‐5,6‐dihydroselenine derivatives were synthesized by the reaction of α‐alkoxy carbonylselenoacetamides with α,β‐unsaturated ketones in the presence of BF3•Et2O. 相似文献
976.
Isaac Eng Ting Lee Akihito Hashidzume Akira Harada 《Macromolecular rapid communications》2015,36(23):2055-2059
This Communication describes a new light‐controlled release system based on molecular recognition of cyclodextrins. Azobenzene (Azo) residue is employed as a photoresponsive guest residue because it can switch the partner from α‐cyclodextrin (αCD) to β‐cyclodextrin (βCD) by irradiation with UV light. Poly(sodium acrylate)s possessing αCD, βCD, and Azo residues (pAαCD, pAβCD, and pAAzo, respectively) are mixed in aqueous solutions to form aggregates through the formation of inclusion complexes of Azo with αCD and/or βCD. A chemical cargo, 1‐pyrenemethylammonium chloride (PyMA), is contained in the aggregates, and its release behavior is investigated by dialysis experiments under UV irradiation. These data indicate that the amount of PyMA released for the pAαCD/pAβCD/pAAzo ternary mixture is approximately three times as high as those for the pAαCD/pAAzo and pAβCD/pAAzo binary mixtures because of the light‐controlled rearrangement of inclusion complexes.
977.
We present a simple and efficient method for calculating symmetrized time correlation functions of neat quantum fluids. Using the pair-product approximation to each complex-time quantum mechanical propagator, symmetrized correlation functions are written in terms of a double integral for each degree of freedom with a purely positive integrand. At moderate temperatures and densities, where the pair-product approximation to the Boltzmann operator is sufficiently accurate, the method leads to quantitative results for the early time part of the correlation function. The method is tested extensively on liquid para-hydrogen at 25 K and used to obtain accurate quantum mechanical results for the initial 0.2 ps segment of the symmetrized velocity autocorrelation function of this system, as well as the incoherent dynamic structure factor at certain momentum transfer values. 相似文献
978.
Takumi Nakanishi Yuta Hori Shuqi Wu Hiroyasu Sato Atsushi Okazawa Prof. Norimichi Kojima Yusuke Horie Hajime Okajima Prof. Akira Sakamoto Yoshihito Shiota Prof. Kazunari Yoshizawa Prof. Osamu Sato 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):14891-14897
A proton–electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials based on proton dynamics. Herein, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling with spin transition. Although the multi-step transition with hysteresis has been observed in various systems, the corresponding behavior of proton transfer has not been reported in crystalline systems; thus, the described iron(II) complex is the first example. Furthermore, because proton transfer occurs only in one of the two ligands and π electrons redistribute in it, the dipole moment of the iron(II) complexes changes with the proton transfer, wherein the total dipole moment in the crystal was canceled out owing to the antiferroelectric-like arrangement. 相似文献
979.
Peng Zhang Yawen Tong Yong Liu Junie Jhon M. Vequizo Hongwei Sun Can Yang Akira Yamakata Fengtao Fan Wei Lin Xinchen Wang Wonyong Choi 《Angewandte Chemie (International ed. in English)》2020,59(37):16209-16217
Polymeric carbon nitride modified with selected heteroatom dopants was prepared and used as a model photocatalyst to identify and understand the key mechanisms required for efficient photoproduction of H2O2 via selective oxygen reduction reaction (ORR). The photochemical production of H2O2 was achieved at a millimolar level per hour under visible‐light irradiation along with 100 % apparent quantum yield (in 360–450 nm region) and 96 % selectivity in an electrochemical system (0.1 V vs. RHE). Spectroscopic analysis in spatiotemporal resolution and theoretical calculations revealed that the synergistic association of alkali and sulfur dopants in the polymeric matrix promoted the interlayer charge separation and polarization of trapped electrons for preferable oxygen capture and reduction in ORR kinetics. This work highlights the key features that are responsible for controlling the photocatalytic activity and selectivity toward the two‐electron ORR, which should be the basis of further development of solar H2O2 production. 相似文献
980.
Kondo T Aoshima S Hirata K Honda K Einaga Y Fujishima A Kawai T 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7545-7548
Crystal-face-selective adsorption of Au nanoparticles (AuNPs) was achieved on polycrystalline boron-doped diamond (BDD) surface via the self-assembly method combined with a UV/ozone treatment. To the best of our knowledge, this is the first report of crystal-face-selective adsorption on an inorganic solid surface. Hydrogen-plasma-treated BDD samples and those followed by UV/ozone treatment for 2 min or longer showed almost no adsorption of AuNP after immersion in the AuNP solution prepared by the citrate reduction method. However, the samples treated by UV/ozone for 10 s showed AuNP adsorption on their (111) facets selectively after the immersion. Moreover, the sample treated with UV/ozone for 40-60 s showed AuNP adsorption on the whole surface. These results indicate that the AuNP adsorption behavior can be controlled by UV/ozone treatment time. This phenomenon was highly reproducible and was applied to a two-step adsorption method, where AuNPs from different batches were adsorbed on the (111) and (100) surface in this order. Our findings may be of great value for the fabrication of advanced nanoparticle-based functional materials via bottom-up approaches with simple macroscale procedures. 相似文献