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51.
Oxosumanenes were synthesized through benzylic oxidation. The electronic and redox properties were revealed to exhibit the expanded π-conjugation compared to sumanene. Single-crystal X-ray analysis of monooxosumanene showed columnar π-stacking in a concave-convex fashion. Stereoselective trimethylation of the trioxo derivative was performed via 1,2-addition to the carbonyl groups.  相似文献   
52.
Coronene (C(24)H(12)) is a flat polyaromatic hydrocarbon consisting of seven peri-fused benzene rings and attracts lots of attention as a fragment of graphene. Using a hybrid method of quantum chemistry and statistical mechanics called RISM-SCF, which is an alternative to QM/MM, the electronic structure and solvation structure of a coronene-transition metal complex were computed in a self-consistent manner. The binding of a ruthenium complex ([C(5)H(5)Ru](+)) was extensively studied, especially the changing of the solvation structure.  相似文献   
53.
Two polymorphic forms (I and II) of 4-fluorophenylpyruvic acid (F-PPA) were obtained by crystallization from different solvents, showing a melting point at 163.2 and 171.0 °C. Crystal structures of polymorphs I and II were determined by X-ray crystallography. IR and Raman spectra of the two polymorphs were measured and the spectral characteristics were compared with those of phenylpyruvic acid. the two polymorphs show similar molecular and crystal structures to each other, except for the molecular geometries of the enol and the carboxylic acid moieties. Distinct IR spectral differences which result from the crystal field splitting were observed between the two polymorphs.  相似文献   
54.
A surface preparation method with fine SiO2 particles in water is developed to flatten Si(0 0 1) surfaces on the nanometer scale. The flattening performance of Si(0 0 1) surfaces after the surface preparation method is investigated by scanning tunneling microscopy. The observed surface is so flat that 95% of the view area (100 × 100 nm2) is composed of only three atomic layers, namely, one dominant layer occupying 50% of the entire area and two adjacent layers. Furthermore, a magnified image shows the outermost Si atoms regularly distributed along the 〈1 1 0〉 direction on terraces.  相似文献   
55.
The optically active (R)- and (S)-flavanones were prepared by an enzymatically enantioselective hydrolysis of (±)-flavanone oxime O-acylates employing lipases, followed by hydrolysis with acid.  相似文献   
56.
In the two-electron reduction of diphenylsulfoxide to diphenylsulfide, which is considered a model reaction of sulfite reduction catalyzed by sulfite reductase, methylviologen-pendent iron(III) porphyrin exhibits much higher catalytic activity than usual iron(III) and manganese(III) tetraphenylporphyrins, while cobalt(II) tetraphenylporphyrin exhibits much less catalytic activity than the others. Discussion about the active species and the reason of the acceleration by methylviologen-pendent is presented.  相似文献   
57.
The p-type (Bi0.25Sb0.75)2Te3 doped with 3-12 wt% excess Te alone and n-type Bi2(Te0.94Se0.06)3 codoped with 0.017-0.026 wt% Te and 0.068-0.102 wt% I were prepared by the Bridgman method, to produce intentionally polycrystalline. Some of the as-grown specimens were annealed, in order to prepare specimens with much different ρ. These polycrystalline specimens have almost the same degree of alignment of the c plane parallel to the freezing direction. The electrical rersistivity ρ and thermal conductivity κ were measured at 298 K along the freezing direction and κ was plotted as a function of ρ. As a result, the lattice components κph obtained by subtracting the electronic component κel from the observed κ were found to decrease almost linearly with a decrease of ρ in both p- and n-type specimens, where κel was calculated using Wiedemann-Franz law. This tendency is consistent with the conventional result that κph becomes negligible small in metals. The significant decrease in κph with decrease in ρ is considered to be caused predominantly by the phonon scattering due to dopants. The relationship between κph and ρ was first clarified in the intermediate region between the metal and insulator.  相似文献   
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The stress-concentration factor for keyways is obtained by the electroplating method of strain analysis which was recently developed in Japan. The stresses in keyways are examined under most practical conditions. The shaft to be examined is set in a boss and fixed with a key so that the torque is wholly transmitted to the test piece through the key. To obtain the limit value for a shaft twisted only through a key, the fitting is devised so as to minimize the surface friction at the fitted portion. The results are compared to those reported previously by other authors in which local effects of the key are ignored.  相似文献   
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