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11.
12.
An two-electrode molecular bridge model that consists of two benzene rings was presented. The characteristics of electronic transport through the nano-molecular bridge was investigated theoretically by using the tight binding approach based on the Green’s function with only one π orbital per carbon atom at the site. Electronic transport probabilities through the molecular bridge from the input to the output terminal were obtained. The electronic current distributions inside the molecular bridge were calculated and shown in graphical analogy by the current density method based on Fisher-Lee formula at the energy points E=±0.68 and E=±1.38 where the peaks of transport probabilities appeared, and the maximum bond electronic current was also presented. The reason why the loop current in the benzene ring is induced by the phase difference within the molecular orbits is explained. 相似文献
13.
From several large supercell MD simulations with an empirical tight-binding method, we have found the long-range structure on the dihydride Si(001) surface. This structure can be viewed as the well-known canted phase with domain walls. The formation energy of a single domain wall on the surface is estimated to be 1.3–1.5 eV. 相似文献
14.
Chuji Aso Sanae Tagami Toyoki Kunitake 《Journal of polymer science. Part A, Polymer chemistry》1970,8(6):1323-1336
Copolymerizations of three phthalaldehyde isomers (M2) with styrene (M1) were carried out in methylene chloride or in toluene with BF3OEt2 catalyst. The monomer reactivity ratios were r1 = 0.77, r2 = 0 for the meta isomer and r1 = 0.60, r2 = 0 for the para isomer. The second aldehyde group of both isomers did not participate in polymerization and acted simply as the electron-withdrawing group, thus reducing the cationic reactivity of these monomers. Copolymerization behaviors of the ortho isomer (o-PhA) were quite different between 0°C and ?78°C. At ?78°C, o-PhA preferentially polymerized to yield “living” cyclopolymers, until an equilibrium concentration of o-PhA monomer was reached. Then, styrene propagated from the living terminal rather slowly. The block structure of the copolymer was confirmed by the chemical and spectroscopic means. In the copolymerization at 0°C, the o-PhA unit in copolymer consisted both of cyclized and uncyclized units. This copolymer seemed to contain short o-PhA sequences. The variation of the o-PhA-St copolymer structure with the polymerization temperature was explained on the basis of whether the polymerization was carried out above or below the ceiling temperature (?43°C) of the homopolymerization of o-PhA. 相似文献
15.
Synthesis of microtubes with a surface of "house of cards" structure via needlelike particles and control of their pore size 总被引:7,自引:0,他引:7
Mitsuhashi K Tagami N Tanabe K Ohkubo T Sakai H Koishi M Abe M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3659-3663
The conditions for synthesizing microtubes with a surface of "house of cards" structure via needlelike particles were examined in detail. Magnesium carbonate trihydrate was formed as a metastable phase in the reaction process using magnesium hydroxide and carbon dioxide as starting materials. Subsequently, in the formation of basic magnesium carbonate from magnesium carbonate trihydrate, microtubes with a surface of house of cards structure were obtained via needlelike particles of magnesium carbonate trihydrate under certain conditions where the temperature and added amount of sodium hydroxide were properly controlled. The pore size of the microtubes could be controlled within a range of 0.5-6 microm by adjusting the condition of needlelike particle formation. In addition, the sustainability of naphthalene release from the microtube was found to be about 6 times higher than that from naphthalene crystal. 相似文献
16.
The coherent quantum transport properties through the spin-polarized polyphenoxyl radical molecule have been investigated, using the density-functional-derived tight-binding model and the Green's functions method. The majority and minority spin components exhibit considerably different transmission spectra in the vicinity of the Fermi level. Namely, each spin component carries a different amount of current when the bias voltage is applied between the two electrodes that sandwich the polyradical molecule. Therefore, if the magnetization axis of the polyradical is fixed by the external magnetic field, and if the spin flip does not occur during the transmission, the assumed molecular bridge is expected to work as a spin filter or a spin valve. Furthermore, as long as the bias voltage is weak, the total spin current is observed to be larger than the current through its reduced molecular form. It indicates that the adsorption of some chemical species on the radical sites can be sensed by the change in conductance of the molecular bridge. 相似文献
17.
Summary The estimation of the Re concentration factor (CF) has been carried out to provide additional field information on the biochemical similarities between Re and Tc. Re concentration in brown seaweed samples from the North Atlantic Coast were measured using ID-ICP-MS. The chemical yields were quantitative, and the concentrations were distributed within a narrow range of 65-80 ng/g d.w. CF of Re was approximately 1.2 . 104 on average, i.e., one order of magnitude less than that found for 99Tc. 相似文献
18.
The behavior of salicylic acid-D-alanine conjugate (salicyl-D-alanine) following intravenous, oral and intracecal administration was examined in rabbits, then compared with that of salicylic acid-L-alanine conjugate (salicyl-L-alanine) as reported previously. Following intravenous administration, salicyl-D-alanine eliminated rapidly from the blood, and its blood concentration was almost identical with that of salicyl-L-alanine. In both cases, salicylic acid could not be detected in the blood, indicating that systemic de-conjugation of D-alanine might not occur. Unchanged salicyl-D-alanine was found in the blood mainly following oral and intracecal administration of salicyl-D-alanine. On the other hand, salicylic acid formed extensively following oral and intracecal administration of salicyl-L-alanine, suggesting that the presystemic de-conjugation of D-alanine and L-alanine was unequal. Furthermore, in vitro incubation of salicyl-D-alanine with cecal content, in which the major source of salicyl-L-alanine hydrolysis is found, showed that the hydrolysis of salicyl-D-alanine was negligible in rabbit intestinal microorganisms. 相似文献
19.
Ni Youyi Zheng Jian Guo Qiuju Wang Hai Tagami Keiko Uchida Shigeo 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):643-651
Journal of Radioanalytical and Nuclear Chemistry - In this study, we developed a method to evaluate the potentially bioavailable fraction of Pu in agricultural soils by determining their water... 相似文献
20.
The characteristics of electron transmission through C70 molecule bridge in which two atomic chain leads are connected to long-axis carbon atoms are investigated theoretically by
using tight-binding approach based on the Green’s function with only one π orbital electron per carbon atom. Electron transmission
through C70 molecule from the input to the output terminal is obtained. From the spectrum, the switching feature of the electron transmission
through C70 is found, and the oscillation property based on the quantized level is explained. The quantum current distributions inside
C70 molecule bridge are calculated and simulated by the quantum current density theory based on Fisher-Lee formula at the energy
point E = −0.2 eV, where the transmission spectrum shows a peak. The maximum and the minimum bond quantum currents are presented,
and the reason why the currents are distributed nonuniformly is explained by the phase difference of the atomic orbits. The
result shows that the currents at each atomic site agree with Kirchhoff quantum current conservation law.
Supported by the National Key Basic Research Development Project (Grant No. 2003CB716204), the International Corporation Project
of the Education Department of China (Grant No. 20050360563), the Key Laboratory of Advanced Photonic and Electronic Materials
of Jiangsu (Grant No. BM2003202) and the State Key Laboratory of Solid State Microstructures of Nanjing University 相似文献