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排序方式: 共有152条查询结果,搜索用时 15 毫秒
121.
Akira Tsuguchi Akira Ohashi Sung-Yong Choi Hisanori Imura Kousaburo Ohashi 《Analytical sciences》2002,18(11):1227-1233
The extraction of vanadium(V) with 2-methyl-8-quinolinol derivatives (HA), such as 2-methyl-8-quinolinol (HMQ), 2-methyl-5-butyloxymethyl-8-quinolinol (HMO4Q), and 2-methyl-5-hexyloxymethyl-8-quinolinol (HMO6Q), from a weakly acidic solution into chloroform was studied in both the absence and presence of 3,5-dichlorophenol (Hdcp) and trioctylphosphine oxide (TOPO) as the synergists. Vanadium(V) was extracted with HA as VO(OH)(A)2 in the absence of synergists, and its extractability increased with an increase in the hydrophobicity of HA. Vanadium(V) was quantitatively extracted from the lower pH region upon the addition of Hdcp and TOPO as VO(OH)(A)2 x Hdcp and VO2(A)(TOPO), respectively. The enhancement of the synergistic effect of Hdcp on the extraction of vanadium(V) with HA increased in the following order: HMQ < HMO4Q < HMO6Q, as opposed to that of TOPO. This result was ascribable to the difference in the mechanisms of the occurrence of the synergistic effect by Hdcp and TOPO. 相似文献
122.
Akira Ohashi Akira Tsuguchi Hisanori Imura Kousaburo Ohashi 《Analytical sciences》2004,20(7):1091-1093
The cloud point extraction behavior of aluminum(III) with 8-quinolinol (HQ) or 2-methyl-8-quinolinol (HMQ) and Triton X-100 was investigated in the absence and presence of 3,5-dichlorophenol (Hdcp). Aluminum(III) was almost extracted with HQ and 4(v/v)% Triton X-100 above pH 5.0, but was not extracted with HMQ-Triton X-100. However, in the presence of Hdcp, it was almost quantitatively extracted with HMQ-Triton X-100. The synergistic effect of Hdcp on the extraction of aluminum(III) with HMQ and Triton X-100 may be caused by the formation of a mixed-ligand complex, Al(dcp)(MQ)2. 相似文献
123.
Akira Ohashi Hirobumi Hoshino Hisanori Imura Kousaburo Ohashi 《Analytical sciences》2006,22(11):1399-1401
The solubility of tris(pentane-2,4-dionato)chromium(III) (Cr(acac)(3)) in supercritical carbon dioxide (SC-CO(2)) containing organic modifiers (1,1,1,3,3,3-hexafluoro-2-propanol (HFP) and 3,5-bis(trifluoromethyl)phenol (BTMP)) of hydrogen-bond donors was investigated by UV/VIS spectrophotometry. A great solubility enhancement of Cr(acac)(3) in SC-CO(2) was accomplished by adding HFP and BTMP. The association constant of Cr(acac)(3) with HFP and BTMP in SC-CO(2) could be determined from the relationship of the solubility enhancement against the concentration of the modifier. The association constant linearly increases with an increase in the acid dissociation constant of the modifiers. 相似文献
124.
Nagahara T Imura K Okamoto H Oguro A Imahori H 《The journal of physical chemistry. B》2005,109(42):19839-19844
We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties. 相似文献
125.
We have investigated optical properties of single gold nanorods by using an apertured-type scanning near-field optical microscope. Near-field transmission spectrum of single gold nanorod shows several longitudinal surface plasmon resonances. Transmission images observed at these resonance wavelengths show oscillating pattern along the long axis of the nanorod. The number of oscillation increases with decrement of observing wavelength. These spatial characteristics were well reproduced by calculated local density-of-states maps and were attributed to spatial characteristics of plasmon modes inside the nanorods. Dispersion relation for plasmons in gold nanorods was obtained by plotting the resonance frequencies of the plasmon modes versus the wave vectors obtained from the transmission images. 相似文献
126.
Hongjing Wang Dr. Masataka Imura Dr. Yoshihiro Nemoto Dr. Liang Wang Dr. Hu Young Jeong Dr. Tokihiko Yokoshima Prof. Osamu Terasaki Prof. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13142-13148
Mesoporous Pt–Ru alloy films with various compositions were synthesized by electrochemical plating in an aqueous surfactant solution. After the removal of surfactants, continuous mesoporous Pt–Ru alloy films possessing uniform mesopores with diameter about 7 nm were obtained. The Ru content in the films could be controlled from 0 to 13 at % by changing the precursor compositions. For all the films, the mesostructural periodicities and the mesopore sizes in the films were not changed. Due to the mesoporous structure and the doped Ru content, our mesoporous Pt–Ru films showed superior electrocatalytic activity for methanol oxidation reaction in comparison with the commercially available Pt catalyst. 相似文献
127.
Hongjing Wang Dr. Masataka Imura Dr. Yoshihiro Nemoto Prof. Dr. Sang‐Eon Park Prof. Dr. Yusuke Yamauchi 《化学:亚洲杂志》2012,7(4):802-808
Well‐ordered mesoporous Pt nanoparticles (MPNs) with uniform olive shapes are synthesized by using two‐dimensional (2D) hexagonal mesoporous silica (SBA‐15) as a hard template. The average particle sizes are controllable in the range of 150 to 230 nm by changing the reduction time. Low‐angle XRD profiles for the obtained MPNs show three distinct peaks assignable to the (10), (11), and (20) planes of a highly ordered 2D hexagonal symmetry. From high‐magnification SEM images, periodically arranged Pt nanowires are observed clearly, which are a negative replica of the 2D hexagonally ordered mesoporous silica (SBA‐15). Furthermore, the single crystallinity of the Pt fcc structure coherently extends over the whole particles. As a result of such unique character as well as high surface area, the obtained MPNs show distinctly enhanced electrocatalytic properties for methanol oxidation reaction compared to other Pt samples, such as Pt black. 相似文献
128.
Two efficient and practical methods of synthesis of the C-10 substituent of DV-7751 (1), a novel quinolone carboxylic acid, were established. The first method utilizes an optical resolution of racemic 8-amino-6-benzyl-6-azaspiro[3.4]octane (13), while the second employs an enantioselective microbial reduction of 6-benzyl-5,8-dioxo-6-azaspiro[3.4]octane (8b). The enantiomeric excess of (S)-8-amino-6-benzyl-6-azaspiro[3.4]octane (11) with each method of synthesis is greater than 96%. 相似文献
129.
Oxygen‐Assisted Synthesis of Mesoporous Palladium Nanoparticles as Highly Active Electrocatalysts 下载免费PDF全文
Dr. Cuiling Li Bo Jiang Dr. Masataka Imura Prof. Dr. Naoto Umezawa Dr. Victor Malgras Prof. Dr. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18671-18676
Mesoporous Pd nanoparticles (MPNs) enclosed by high‐index facets have been successfully prepared by taking advantage of successive oxygen adsorption and desorption caused by the oxidative etching effect. The as‐prepared MPNs exhibit excellent performance toward formic acid electro‐oxidation, which is due to the synergetic effect between the diffusion‐feasible tubular mesochannels and the high index facets. 相似文献
130.
Dual Soft‐Template System Based on Colloidal Chemistry for the Synthesis of Hollow Mesoporous Silica Nanoparticles 下载免费PDF全文
Yunqi Li Dr. Bishnu Prasad Bastakoti Dr. Masataka Imura Jing Tang Prof. Ali Aldalbahi Dr. Nagy L. Torad Prof. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6375-6380
A new dual soft‐template system comprising the asymmetric triblock copolymer poly(styrene‐b‐2‐vinyl pyridine‐b‐ethylene oxide) (PS‐b‐P2VP‐b‐PEO) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to synthesize hollow mesoporous silica (HMS) nanoparticles with a center void of around 17 nm. The stable PS‐b‐P2VP‐b‐PEO polymeric micelle serves as a template to form the hollow interior, while the CTAB surfactant serves as a template to form mesopores in the shells. The P2VP blocks on the polymeric micelles can interact with positively charged CTA+ ions via negatively charged hydrolyzed silica species. Thus, dual soft‐templates clearly have different roles for the preparation of the HMS nanoparticles. Interestingly, the thicknesses of the mesoporous shell are tunable by varying the amounts of TEOS and CTAB. This study provides new insight on the preparation of mesoporous materials based on colloidal chemistry. 相似文献