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排序方式: 共有397条查询结果,搜索用时 15 毫秒
1.
The ion-pair extraction equilibria of dibenzo-18-crown-6 (DB18C6) complexes of Na+, K+, Rb+ and Cs+ (M+) with picrate ion (Pic−) into 1,2-dichloroethane (1,2-DCE) have been studied at 25.0°C. In the case of the Rb+ and Cs+ systems, the extraction results were interpreted by taking into consideration the formation of a (DB18C6)2 -M+ complex in 1,2-DCE. The thermodynamic constants of extraction,
, and ion-pair formation in 1,2-DCE,
, of ion pairs of the DB18C6-M+ complexes with Pic− were determined. By using the distribution coefficient of M+·Pic− the thermodynamic formation constants of the DB18C6-M+ complexes in 1,2-DCE,
, were evaluated. Consequently the component equilibrium constants of the ion-pair extraction were completely determined and a contribution of these constants to the difference of
value was discussed. The
value in 1,2-DCE is quite high compared with that in solvating solvents and log
decreases linearly with increasing Gutmann donor number of solvents. 相似文献
2.
T. Kato K. Masumoto N. Sato N. Suzuki 《Journal of Radioanalytical and Nuclear Chemistry》1976,32(1):51-70
A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the
effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many
elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated
by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological
and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive
multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements. 相似文献
3.
Alternative oxidase (AOX) is a nonproton motive quinol–oxygen oxidoreductase which is a component of the mitochondrial respiratory chain in higher plants. In this study, we have characterized the catalytic activity and regulatory behaviors of Arum concinnatum AOX isoforms, namely AcoAOX1a and AcoAOX1b, and their artificial mutants in HeLa cells. We demonstrated that substitution of the motif-like sequence ENV on the C-terminal half of AcoAOX1a for QDT diminishes its activity and proposed that the innate inactivity of AcoAOX1b in HeLa cells is, at least in part, attributable to its QDT motif. Furthermore, we show that introduction of F130L in the hydrophilic N-terminal extension of AcoAOX1a resulted in greater activity in the presence of pyruvate. This result indicates that functional significance of the N-terminal extension is not particular to the conventional regulatory cysteine. On the basis of these findings, we discuss new insights into the structural integrity of AOX in HeLa cells and the applicability of mammalian cells for functional analysis of this enzyme. 相似文献
4.
Y. Nakanishi T. Tanizawa M. Matsukawa M. Apostu A. Revcolevschi N. Môri 《Solid State Communications》2006,138(9):441-443
We investigated the effect of pressure on the magnetic properties of a single crystal of the bilayer manganese oxide (Pr0.6La0.4)1.2Sr1.8Mn2O7 by means of DC magnetization measurements under pressure. The ferromagnetic transition, which is accompanied by a metal-insulator transition, is highly sensitive to pressure. The pressure causes a structural variation, which affects the magnetic properties. We discuss the pressure dependence of the 3d electronic state of the Mn ion in this system. 相似文献
5.
A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has
been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this
method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly
toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is
quite simple and gives good reproducible results for at least 12 elements. 相似文献
6.
Cyril Martini Dr. Guillaume Poize Daniel Ferry Dr. Daiki Kanehira Noriyuki Yoshimoto Dr. Jörg Ackermann Dr. Frédéric Fages Prof. Dr. 《Chemphyschem》2009,10(14):2465-2470
We describe herein the design, synthesis and detailed structural characterization of hybrid 1D nanostructures. They are prepared by supramolecular self‐assembly of oligothiophene molecules on the surface of zinc oxide nanorods in solution at room temperature. Electronic absorption spectroscopy and X‐ray diffraction show that both organic and inorganic components in the coaxial p–n heterojunctions are crystalline. Especially, it is demonstrated that the organic compounds form a self‐assembled monolayer at the surface of the nanorods, which is not the case when zinc oxide quantum dots are instead used. As a result of their hybrid nature, the 1D nanostructures lead to ambipolar semiconducting nanostructured materials as active layers in field‐effect transistors. 相似文献
7.
Sho Inagaki Akari Sato Haruka Sato Satoru Tamura Tomikazu Kawano 《Tetrahedron letters》2017,58(52):4872-4875
A simple and efficient synthesis of 4,5-dihydro-4-oxo-3-furancarboxylates using an acylative intramolecular cyclization of sulfonium salts is described. The reaction involved the efficient formation of a mixed anhydride between a linear carboxylic acid and trifluoroacetic anhydride in the presence of N-methylimidazole, followed by the sequential conversion into a highly reactive acylammonium species in situ. This procedure is easily handled, uses readily available inexpensive reagents, and provides a variety of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates. 相似文献
8.
The metastable zone width (MSZW, ΔTm) and induction time (tind) were determined with computer simulation for seeded batch crystallization of potassium sulfate from aqueous solution. The MSZW and induction time determined with simulation showed the same behavior as experimental values reported in the literature; log (ΔTm) increased linearly with an increase in log R (R: cooling rate) and tind decreases in proportion to (ΔT)−n (ΔT: supercooling, n: nucleation order in the secondary rate expression of B=kn(ΔT)n). The secondary nucleation parameters (kn and n) were deduced both from the simulated MSZW and induction times by using the previously proposed model [J. Cryst. Growth, 2010, 312, 548–554]. The secondary nucleation rate calculated with the deduced parameters was in agreement with that calculated with the parameters input for simulation. 相似文献
9.
Dr. Songlin Xue Dr. W. Ryan Osterloh Xiaojuan Lv Ningchao Liu Yimei Gao Dr. Haitao Lei Dr. Yuanyuan Fang Dr. Zhongti Sun Dr. Peifeng Mei Dr. Daiki Kuzuhara Dr. Naoki Aratani Dr. Hiroko Yamada Dr. Rui Cao Dr. Karl M. Kadish Dr. Fengxian Qiu 《Angewandte Chemie (International ed. in English)》2023,62(17):e202218567
The molecular structure, electrochemistry, spectroelectrochemistry and electrocatalytic oxygen reduction reaction (ORR) features of two CoII porphyrin(2.1.2.1) complexes bearing Ph or F5Ph groups at the two meso-positions of the macrocycle are examined. Single crystal X-ray analysis reveal a highly bent, nonplanar macrocyclic conformation of the complex resulting in clamp-shaped molecular structures. Cyclic voltammetry paired with UV/Vis spectroelectrochemistry in PhCN/0.1 M TBAP suggest that the first electron addition corresponds to a macrocyclic-centered reduction while spectral changes observed during the first oxidation are consistent with a metal-centered CoII/CoIII process. The activity of the clamp-shaped complexes towards heterogeneous ORR in 0.1 M KOH show selectivity towards the 4e− ORR pathway giving H2O. DFT first-principle calculations on the porphyrin catalyst indicates a lower overpotential for 4e− ORR as compared to the 2e− pathway, consistent with experimental data. 相似文献
10.
This paper presents a new method of multispectral hyperbolic incoherent holography in which a hyperbolic volume interferogram was directly measured by an appropriate designed interferometer. This method enables to obtain a set of spectral components of three-dimensional images and continuous spectra for spatially incoherent, polychromatic objects. We introduced a calibration method of a phase aberration of the interferometer. The spectral resolution and spatial resolutions are investigated based on analytical solution of impulse response function of hyperbolic holography. From experimental results and theoretical predictions, the validity of the calibration method was confirmed. Experimental results agree with the theoretical ones. Consequently, the retrieved images obtained by the method are shown to demonstrate the performance of the method. 相似文献