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571.
Kudo M Ohkawa H Sugimoto W Kumada N Liu Z Terasaki O Sugahara Y 《Inorganic chemistry》2003,42(14):4479-4484
The conversion process of an Aurivillius phase, Bi(2)W(2)O(9), into a layered tungstic acid by hydrochloric acid treatment has been investigated, and resultant H(2)W(2)O(7) x nH(2)O has been fully characterized. The c parameter of Bi(2)W(2)O(9) [2.37063(5) nm] decreases to 2.21(1) nm in an acid-treated product dried at ambient temperature. The a and b parameters of Bi(2)W(2)O(9) [a = 0.54377(1) nm and b = 0.54166(1) nm] also decrease slightly to a = 0.524(1) nm and b = 0.513(1) nm in the acid-treated product dried at ambient temperature, indicating structural changes in the ReO(3)-like slabs in Bi(2)W(2)O(9) upon acid treatment. Drying at 120 degrees C leads to a further decrease in the c parameter [1.86(1) nm] with no notable change in the a and b parameters [a = 0.5249(2) nm and b = 0.513(2) nm]. The formation of an expandable layered structure is demonstrated by the successful intercalation of n-octylamine [interlayer distance 2.597(9) nm] and n-dodecylamine [interlayer distance 3.56(2) nm]. The compositions of the acid-treated products are determined to be H(2)W(2)O(7) x nH(2)O typically with n = 0.58 for the air-dried product and n = 0 for the product dried at 120 degrees C. As a consequence, the composition of the layer is H(2)W(2)O(7), and the decrease in the c parameter upon drying is ascribable to the loss of interlayer water. Scanning electron microscopy reveals no morphological change during acid treatment, which strongly suggests a selective leaching of the bismuth oxide sheets as a reaction mechanism. High-resolution transmission electron microscopy (HREM) observation of the acid-treated product shows consistency with a structural model for H(2)W(2)O(7), derived from Bi(2)W(2)O(9) through removal of the bismuth oxide sheets and contraction along the c axis. HREM observation also reveals that the WO(6) octahedra arrangement changes slightly with acid treatment. A one-dimensional electron density map projected on the c axis for the product dried at 120 degrees C, H(2)W(2)O(7), shows good consistency with that calculated for the structural model. 相似文献
572.
Wataru Sakamoto Ken-ichi Mimura Takafumi Naka Tetsuo Shimura Toshinobu Yogo 《Journal of Sol-Gel Science and Technology》2007,42(3):213-220
Ba(Zr,Ti)O3/LaNiO3 layered thin films have been synthesized by chemical solution deposition (CSD) using metal-organic precursor solutions. Ba(Zr,Ti)O3 thin films with smooth surface morphology and excellent dielectric properties were prepared on Pt/TiO
x
/SiO2/Si substrates by controlling the Zr/Ti ratios in Ba(Zr,Ti)O3. Chemically derived LaNiO3 thin films crystallized into the perovskite single phase and their conductivity was sufficiently high as a thin-film electrode.
Ba(Zr,Ti)O3/LaNiO3 layered thin films of single phase perovskite were fabricated on SiO2/Si and fused silica substrates. The dielectric constant of a Ba(Zr0.2Ti0.8)O3 thin film prepared at 700°C on a LaNiO3/fused silica substrate was found to be approximately 830 with a dielectric loss of 5% at 1 kHz and room temperature. Although
the Ba(Zr0.2Ti0.8)O3 thin film on the LaNiO3/fused silica substrate showed a smaller dielectric constant than the Ba(Zr0.2Ti0.8)O3 thin film on Pt/TiO
x
/SiO2/Si, small temperature dependence of dielectric constant was achieved over a wide temperature range. Furthermore, the fabrication
of the Ba(Zr,Ti)O3/LaNiO3 films in alternate thin layers similar to a multilayer capacitor structure was performed by the same solution deposition
process. 相似文献
573.
Joonho?LeeEmail author Wataru?Shimoda Toshihiro?TanakaEmail author 《Monatshefte für Chemie / Chemical Monthly》2005,136(11):1829-1834
Summary. Temperature dependence of the surface tension of liquid Sn–Ag and Sn–Cu base lead-free solder alloys and oxygen partial pressure
dependence of liquid Sn–Ag alloy were evaluated using the experimental data obtained, respectively, by the constrained drop
method and the sessile drop method in the previous studies [1, 2]. The temperature dependences of the surface tension have
maximum positive values when the mol fraction of Ag and Cu is about 0.7, while those for pure liquid Sn, Ag, and Cu have negative
values. The calculated values based on Butler’s equations were found to be in reasonable agreement with those of the experimental data. The oxygen partial pressure dependences
of the surface tension of liquid Sn–Ag alloys at 1253 K have a minimum value when the mol fraction of Ag is about 0.9 and
the oxygen partial pressure is less than about 10−13 atm. From this, it is considered that the oxygen adsorption increased by adding Ag to Sn when the mol fraction of Ag is less
than 0.9. 相似文献
574.
Jiangyang Liu Kazuki Nagashima Yuki Nagamatsu Takuro Hosomi Hikaru Saito Chen Wang Wataru Mizukami Guozhu Zhang Benjarong Samransuksamer Tsunaki Takahashi Masaki Kanai Takao Yasui Yoshinobu Baba Takeshi Yanagida 《Chemical science》2021,12(14):5073
The surface cation composition of nanoscale metal oxides critically determines the properties of various functional chemical processes including inhomogeneous catalysts and molecular sensors. Here we employ a gradual modulation of cation composition on a ZnO/(Cu1−xZnx)O heterostructured nanowire surface to study the effect of surface cation composition (Cu/Zn) on the adsorption and chemical transformation behaviors of volatile carbonyl compounds (nonanal: biomarker). Controlling cation diffusion at the ZnO(core)/CuO(shell) nanowire interface allows us to continuously manipulate the surface Cu/Zn ratio of ZnO/(Cu1−xZnx)O heterostructured nanowires, while keeping the nanowire morphology. We found that surface exposed copper significantly suppresses the adsorption of nonanal, which is not consistent with our initial expectation since the Lewis acidity of Cu2+ is strong enough and comparable to that of Zn2+. In addition, an increase of the Cu/Zn ratio on the nanowire surface suppresses the aldol condensation reaction of nonanal. Surface spectroscopic analysis and theoretical simulations reveal that the nonanal molecules adsorbed at surface Cu2+ sites are not activated, and a coordination-saturated in-plane square geometry of surface Cu2+ is responsible for the observed weak molecular adsorption behaviors. This inactive surface Cu2+ well explains the mechanism of suppressed surface aldol condensation reactions by preventing the neighboring of activated nonanal molecules. We apply this tailored cation composition surface for electrical molecular sensing of nonanal and successfully demonstrate the improvements of durability and recovery time as a consequence of controlled surface molecular behaviors.Unexpected features of surface Cu2+ on ZnO/(Cu1−xZnx)O nanowires for molecular transformation and electrical sensing of carbonyl compounds were found. 相似文献
575.
Mitsuru Yoshioka Teruji Tsuji Shoichiro Uyeo Sadao Yamamoto Tsutomu Aoki Yasuhiro Nishitani Sachio Mori Hisao Satoh Yoshinori Hamada Hiroyuki Ishitobi Wataru Nagata 《Tetrahedron letters》1980,21(4):351-354
Stereocontrolled and industrially feasible synthesis of a new antibiotic and related derivatives, which is characterized by using all the carbon atoms of the penicillin skeleton, is described. 相似文献
576.
Wataru Ninomiya Yasuhiko Tanabe Ken-Ichiro Sotowa Toshiya Yasukawa Shigeru Sugiyama 《Research on Chemical Intermediates》2008,34(8-9):663-668
Dehydrogenation of decalin to naphthalene through tetralin and that of dicyclohexyl to biphenyl through phenylcyclohexane with Pt/C and Pd/C was investigated mainly under the liquid film state, in which the catalyst was just wet but not suspended and covered with a thin film of liquid substrate. To improve the catalytic activities, the effects of the addition of tellurium into Pd/C were investigated to reveal that the combination of tellurium, palladium and conjugated systems produced during the dehydrogenation of cycloalkames was important to the improvement of the activities. 相似文献
577.
We prove two nonlinear ergodic theorems for noncommutative semigroups of nonexpansive mappings in Banach spaces. Using these
results, we obtain some nonlinear ergodic theorems for discrete and one-parameter semigroups of nonexpansive mappings.
Dedicated to Professors Albrecht Dold and Ed Fadell 相似文献
578.
Wataru Takahashi 《Journal of Fixed Point Theory and Applications》2007,1(1):135-147
In this paper, we first prove a strong convergence theorem for resolvents of accretive operators in a Banach space by the
viscosity approximation method, which is a generalization of the results of Reich [J. Math. Anal. Appl. 75 (1980), 287–292],
and Takahashi and Ueda [J. Math. Anal. Appl. 104 (1984), 546–553]. Further using this result, we consider the proximal point
algorithm in a Banach space by the viscosity approximation method, and obtain a strong convergence theorem which is a generalization
of the result of Kamimura and Takahashi [Set-Valued Anal. 8 (2000), 361–374].
Dedicated to the memory of Jean Leray 相似文献
579.
Koji Aoyama Yasunori Kimura Wataru Takahashi Masashi Toyoda 《Nonlinear Analysis: Theory, Methods & Applications》2007
In this paper, to find a common fixed point of a family of nonexpansive mappings, we introduce a Halpern type iterative sequence. Then we prove that such a sequence converges strongly to a common fixed point of nonexpansive mappings. Moreover, we apply our result to the problem of finding a common fixed point of a countable family of nonexpansive mappings and the problem of finding a zero of an accretive operator. 相似文献
580.
Wataru Takahashi Yukio Takeuchi 《Journal of Mathematical Analysis and Applications》2008,341(1):276-286
In this paper, we prove a strong convergence theorem by the hybrid method for a family of nonexpansive mappings which generalizes Nakajo and Takahashi's theorems [K. Nakajo, W. Takahashi, Strong convergence theorems for nonexpansive mappings and nonexpansive semigroups, J. Math. Anal. Appl. 279 (2003) 372-379], simultaneously. Furthermore, we obtain another strong convergence theorem for the family of nonexpansive mappings by a hybrid method which is different from Nakajo and Takahashi. Using this theorem, we get some new results for a single nonexpansive mapping or a family of nonexpansive mappings in a Hilbert space. 相似文献