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31.
32.
Kan Nakatsuji Yuma Iwasaki Takushi Iimori Masamichi Yamada Fumio Komori 《Surface science》2011,605(19-20):1818-1825
Nanostructures and nanopattern formation by mixing Rh atoms were studied on the N-saturated Cu(001) surface using scanning tunneling microscopy and X-ray photoemission spectroscopy. Most of the Rh atoms are in the topmost layer of the surface, and make a line structure of two atomic width in the <100> direction. Each Rh atom in the line is bonded to one N atom. The density of trench-like structures at the N-saturated surface decreases with increasing the density of the lines. This indicates that the line structure reduces the surface stress induced by N adsorption. When the Rh atoms cover more than a quarter of surface on average, the lines form a rectangular pattern at the surface. The average separation decreases with the increase of the Rh density, and is 4 nm for the 30% Rh coverage. The pattern formation is attributed to the efficient reduction of lattice strain as the grid pattern on the partially N-adsorbed Cu(001) surface. 相似文献
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34.
Self-assembled MnN nanoislands have been prepared on Cu(001) substrate. The nanoislands show a square shape and a well-defined size. They are regularly arrayed with a periodicity of (3.5+/-0.1) nanometer and form a two-dimensional square superstructure. The MnN island superstructure is stabilized by a short-range mechanism. A structural model has been proposed to explain the self-assembly and the high quality of the superstructure. 相似文献
35.
[reaction: see text] The conjugate reduction of cinnamates with hydrosilane and chiral Rh(Phebox-ip) catalyst in the presence of excess acetone is shown to provide the corresponding intermolecular reductive aldol product in extremely high enantioselectivity (up to 98%). Several cinnamates and crotonate substrates and several ketone acceptors were also examined. 相似文献
36.
The abilities of multifunctional polyelectrolytes to enhance aluminum hydroxide dispersion and inhibit silica scale formation were examined in a pilot cooling water system. The following multifunctional polyelectrolytes were studied: a terpolymer of acrylic acid (AA), 2-acrylamide-2-methyl propane sulfonic acid (SA) and N-vinylpyrrolidone (NVP) (P(AA/SA/NVP)), acrylic acid homopolymer (P(AA)) and a copolymer of AA and SA (P(AA/SA)). The order of inhibition ability was P(AA/SA/NVP)>P(AA/SA)>P(AA), and was consistent with that of the dispersing ability for aluminum hydroxide. Other terpolymers incorporating different nonionic monomers were also examined and factors affecting their inhibition abilities were investigated, based on interaction energies calculated by density functional theory. Based on the correlation between scale inhibition abilities and interaction energies, we elucidated that the effective nonionic monomer of terpolymer for silica scale inhibition had low affinity for aluminum hydroxide and high affinity for H(2)O and Si(OH)(3)O(-). The affinities of nonionic monomer for aluminum hydroxide and H(2)O suggested that there was proper conformation of polyelectrolyte adsorbed for effectively dispersing aluminum hydroxide. Also, high affinity of nonionic monomer for Si(OH)(3)O(-) suggested that interacting Si(OH)(3)O(-) is an important role of inhibition of silica scale formation. 相似文献
37.
Shuqin Bai Yutaka Tsuji Yoshihiro Okaue Takushi Yokoyama 《Journal of solution chemistry》2011,40(2):348-356
The formation of a silicic acid–tiron (a derivative of catechol) complex was investigated in aqueous solution with various
molar ratios of tiron to silicic acid (tiron/Si) or with various pH using 29Si NMR. Only the 1:3 silicic acid–tiron complex was detected in despite of the range of tiron/Si molar ratios. This complex
is stable in the pH range from 6 to 10. This indicates that the formation of a hydrogen bond (SiOH⋅⋅⋅O− in tiron), due to
dissociation of H+ from hydroxy groups of tiron, may be a trigger for the formation of the complex. Around pH=6, the formation of the complex
occurs when the tiron/Si molar ratio is larger than 3 and most of silicic acid is converted to the complex when the ratio
is larger than 25. Based on the temperature dependence of the 29Si NMR spectra for the complex, the existence of two possible meridional and facial isomers was confirmed. The conditional
formation constant for the 1:3 silicic acid–tiron complex was defined as Eq. 8 and estimated to be 2.0 mol−1⋅dm3 for the facial complex and 4.1 mol−1⋅dm3 for the meridional complex, respectively. 相似文献
38.
39.
Takushi Kurihara Tsutomu Tani Sigeru Maeyama Yasuhiko Sakamoto 《Journal of heterocyclic chemistry》1980,17(5):945-951
The reaction of ethyl 3-ethoymethylene-2,4-dioxovalerate (EMDV) ( 1 ) with 2-aminobenzamide ( 2 ), 2-aminobenzthioamide ( 3 ), 2-aminobenzmethylamide ( 4 ) and 3-amino-2-methyl- or phenylpyrazole-4-carbox-amides ( 6 and 7 ) produced ethyl 3-aminomethylene-2,4-dioxovalerates ( 10, 15, 16, 18 and 19 ), which led to pyrrolo[1,2-a]quinazoline-1,5-diones ( 11, 22 and 23 ) and pyrrolo[1,2-a]pyrazolo[4,3-e]pyrimidine-1,5-diones ( 24 and 25 ) under the acidic condition, respectively. Analogously, 2-aminothiophenol reacted with 1 to give 21 , which was subsequently derived to pyrrolo[1,2-a]benzothiazolin-l-one ( 26 ) under the neutral condition. Furthermore, we prepared the heterocyclic steroidal molecules ( 41, 43, 45, 47, 49 and 51 ) by condensation of 11 and 26 with hydrazine, methylhydrazine and phenylhydrazine. 相似文献
40.
Takushi Kurihara Eiji Kawasaki Takamasa Morita Keiko Nasu 《Journal of heterocyclic chemistry》1985,22(3):785-791
Synthesis and reactivity of 6-ethoxycarbonyl-, 6-phenyl- and 6-methyl-5a-acetyl-6a-ethoxycarbonyl-5a,6a-di-hydro-6H-cyclopropa[e]pyrazolo[1,5-a]pyrimidine-3-carbonitriles 4 , 5 , and 7 are described. 相似文献