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51.
Ninomiya K Kurita T Hohsaka T Sisido M 《Chemical communications (Cambridge, England)》2003,(17):2242-2243
A simple and versatile method for aminoacylation of a dinucleotide (pdCpA) in aqueous micellar solution was developed by using a hydrophobic amino acid derivative, N-pentenoyl-L-2-naphthylalanine cyanomethyl ester (Pen-napAla-OCM), and a CTACl micelle. 相似文献
52.
The electronic properties of double strands composed of trimeric LNA, PNA, DNA and RNA single strands were investigated by density-functional molecular orbital calculations. The computed hybridization energies for the double strands involving PNA or LNA are larger than those for DNA-DNA and RNA-RNA. The larger stability is attributed to the presence of a larger positive charge of the hydrogen atoms contributing to the hydrogen bonds in the PNA-DNA and LNA-DNA double-strands. These results are comparable to the experimental finding that PNA and LNA single strands display high affinity toward a complementary DNA or RNA single strand. 相似文献
53.
Benzoins are simply oxidized to benzils in excellent yields with a catalytic amount of triarylstibanes under an aerobic condition. This catalytic oxidation is heteroatom-specific in the antimony compound and no reaction take place with other group 15 reagents such as triphenylphosphane, -arsane and -bismuthane. The reaction should involve an oxidation-reduction cycle between stibane Sb(III) and stiborane Sb(V) under air. 相似文献
54.
E. Shibano S. Fujiwara K. Kohno N. S. Takahashi S. Kurita 《Crystal Research and Technology》1993,28(4):469-477
Liquid phase epitaxial layers of AlGaInP were successfully grown on Al0.9Ga0.1 As buffer layer with varying aluminum melt composition. Epitaxial layers were characterised by using a scanning elelctron microscope, X-ray diffraction, photoluminescence (PL) and Auger depth profile measurements. The shortest peak wavelength of PL spectra obtained in the samples was 630 nm at room temperature. It was found that the thickness of the AlGaInP layer is very small due to rapid change of aluminum in the melt composition. 相似文献
55.
56.
F. Ronning E.D. Bauer T. Park N. Kurita T. Klimczuk R. Movshovich A.S. Sefat D. Mandrus J.D. Thompson 《Physica C: Superconductivity and its Applications》2009,469(9-12):396-403
We review the properties of Ni-based superconductors which contain Ni2X2 (X = As, P, Bi, Si, Ge, B) planes, a common structural element found also in the recently discovered FeAs superconductors. Strong evidence for the fully gapped nature of the superconducting state has come from field dependent thermal conductivity results on BaNi2As2. Coupled with the lack of magnetism, the majority of evidence suggests that the Ni-based compounds are conventional electron–phonon mediated superconductors. However, the increase in Tc in LaNiAsO with doping is anomalous, and mimics the behavior in LaFeAsO. Furthermore, comparisons of the properties of Ni- and Fe-based systems show many similarities, particularly with regards to structure–property relationships. This suggests a deeper connection between the physics of the FeAs superconductors and the related Ni-based systems which deserves further investigation. 相似文献
57.
58.
With a view to developing a new proton conducting solid electrolyte usable at more elevated temperatures, the proton conduction
in α-alumina was examined by reviewing the historical literatures and our recent works. It was clarified that acceptor-doped
α-alumina had the possibility to exhibit a certain amount of proton conduction when hydrogen or water vapor was contained
in the surrounding. In the case of Mg-doped α-alumina, proton conduction was found to dominate in the considerably wide range
of oxygen and hydrogen potentials at temperatures 1273–1673 K. The excellent performance of the hydrogen sensor for molten
metals employing Mg-doped α-alumina was experimentally ascertained. 相似文献
59.
It was recently demonstrated that the anisotropic phonon heat transport behavior is a good probe of the stripe formation in La(2-x)Sr(x)CuO(4) (LSCO) [Phys. Rev. B 67, 104503 (2003)]]. Using this probe, we examined an electron-doped cuprate Pr(1.3-x)La(0.7)Ce(x)CuO(4) (PLCCO) and found that essentially the same features as those in LSCO are observed. Moreover, the in-plane resistivity rho(ab) of lightly doped PLCCO shows metallic behavior (drho(ab)/dT>0) in the Néel ordered state with a mobility comparable to that in LSCO. It is discussed that these peculiar properties in common with LSCO signify the existence of stripes in electron-doped cuprates. 相似文献
60.
Kurita J Shimahara H Utsunomiya-Tate N Tate S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,163(1):163-173
The chemical shifts of nuclei that have chemical shielding anisotropy, such as the 15N amide in a protein, show significant changes in their chemical shifts when the sample is altered from an isotropic state to an aligned state. Such orientation-dependent chemical shift changes provide information on the magnitudes and orientation of the chemical shielding tensors relative to the molecule's alignment frame. Because of the extremely high sensitivity of the chemical shifts to the sample conditions, the changes in chemical shifts induced by adding aligned bicelles do not arise only from the protein alignment but should also include the accumulated effects of environmental changes including protein-bicelle interactions. With the aim of determining accurate 15N chemical shielding tensor values for solution proteins, here we have used magic angle sample spinning (MAS) to observe discriminately the orientation-dependent changes in the 15N chemical shift. The application of MAS to an aligned bicelle solution removes the torque that aligns the bicelles against the magnetic field. Thus, the application of MAS to a protein in a bicelle solution eliminates only the molecular alignment effect, while keeping all other sample conditions the same. The observed chemical shift differences between experiments with and without MAS therefore provide accurate values of the orientation-dependent 15N chemical shifts. From the values for ubiquitin in a 7.5% (w/v) bicelle medium, we determined the 15N chemical shielding anisotropy (CSA) tensor. For this evaluation, we considered uncertainties in measuring the 1H-15N dipolar couplings and the 15N chemical shifts and also structural noise present in the reference X-ray structure, assuming a random distribution of each NH bond vector in a cone with 5 degrees deviation from the original orientation. Taking into account these types of noise, we determined the average 15N CSA tensor for the residues in ubiquitin as Delta sigma=-162.0+/-4.3 ppm, eta=0.18+/-0.02, and beta=18.6+/-0.5 degrees, assuming a 1H-15N bond length of 1.02 A. These tensor values are consistent with those obtained from solid-state NMR experiments. 相似文献