Inclusion behaviour of benzoic acid towards intercalates of α- and γ-zirconium hydrogen phosphates with 2-aminopropylamino-substituted β-cyclodextrin

The inclusion behaviour of benzoic acid towards intercalates of - and -zirconium hydrogen phosphates with mono[6-(2-aminopropylamino)-6-deoxy]--cyclodextrin (CDpn) has been studied at 25°C. Both intercalates take up benzoic acid to form a complex, with an accompanying partial release of CDpn. It is concluded that the remaining CDpn molecules in the -complex are rearranged as a bilayer with their cavity axes perpendicular to the phosphate layers. Those in the -complex act as a molecular prop to maintain the initial structure in which the CDpn molecules are arranged as a bilayer with their cavity axes parallel to the phosphate layers. The benzoic acid molecules are embedded inside and outside the CDpn cavity. The pore volume between the CDpn molecules amounts to approximately 0.07 and 0.29 cm³ per gram of the - and -complexes, respectively.     

Field survey of Glycyrrhiza plants in central Asia (2). Characterization of phenolics and their variation in the leaves of Glycyrrhiza plants collected in Kazakhstan

A new prenylated flavanone, licoleafol, and a new prenylated dihydrostilbene, uralstilbene, together with four known compounds, 8-dimethylallyleriodictyol, sophoraflavanone B, gancaonin R, and 6-dimethylallyleriodictyol, were isolated from the leaves of Glycyrrhiza uralensis collected in Kazakhstan. HPLC analysis of the leaves of Glycyrrhiza plants collected in Kazakhstan showed that both G. uralensis-specific and Glycyrrhiza glabra-specific compounds were detected in the leaves of the morphologically intermediate-type plants, suggesting that the intermediate-type plant is a hybrid of G. glabra and G. uralensis. In addition, HPLC profiles of leaf extracts from offspring of intermediate-type plants were divided into the three types: the G. uralensis type, G. glabra type, and the intermediate type. From these results, it appears likely that the intermediate-type plant back-crosses with G. glabra and G. uralensis to generate a G. glabra-type plant and a G. uralensis-type plant, respectively.     

Structure and hypochromism of (6,9) (9′,6′) purinophanes

The structure of the title compound 1a was determined to be a cross-stacking form with an interplanar distance of ca. 3.3 Å by X-ray analysis. On the basis of this structure, the hypochromicity of 1a was calculated by the ASMO SCF CI method.     

Complexation of copper(II)-montmorillonite with a modified cyclodextrin

The uptake reaction of Cu(II)-montmorillonite with mono-(6--aminoethylamino-6-deoxy)--cyclodextrin (CDen) has been examined at 25°C. The CDen molecules in their neutral or cationic forms are taken up by forming complexes with the interlayer Cu(II) ions (Cu_int) and by displacing protons at the clay surface. At low uptakes of CDen, 11 complexes of CDen with Cu_int are intercalated as a monolayer of 13.7 Å in thickness, with their opening faces parallel to the interlayer surface. At higher contents, the CDen-Cu_int complexes are more voluminously packed to form two intercalated phases with larger spacings until a bilayer of 23.9 Å in thickness is formed. The uptake by the mode of ion exchange proceeds increasingly at the intermediate uptake stage. At higher levels, however, this additional uptake is decreased rapidly due to the increase in the pH of solution, resulting in a maximum in the curve of CDen uptake against CDen added.     

Robust Characterization of Multidimensional Scaling Relations between Size Measures for Business Firms

Although the sizes of business firms have been a subject of intensive research, the definition of a “size” of a firm remains unclear. In this study, we empirically characterize in detail the scaling relations between size measures of business firms, analyzing them based on allometric scaling. Using a large dataset of Japanese firms that tracked approximately one million firms annually for two decades (1994–2015), we examined up to the trivariate relations between corporate size measures: annual sales, capital stock, total assets, and numbers of employees and trading partners. The data were examined using a multivariate generalization of a previously proposed method for analyzing bivariate scalings. We found that relations between measures other than the capital stock are marked by allometric scaling relations. Power–law exponents for scalings and distributions of multiple firm size measures were mostly robust throughout the years but had fluctuations that appeared to correlate with national economic conditions. We established theoretical relations between the exponents. We expect these results to allow direct estimation of the effects of using alternative size measures of business firms in regression analyses, to facilitate the modeling of firms, and to enhance the current theoretical understanding of complex systems.     

CO laser-microwave double-resonance spectroscopy of H2CO with intense Stark field: Precise measurement of dipole moment in the ground and ν2 vibrational states

Stark-shifted microwave transitions in the ground and ν₂ vibrational states of H₂CO were observed by means of CO laser-microwave double-resonance with intense electric field. High sensitivity and precision were attained by the use of multireflection absorption cell, optical-flat Stark plates, and microwave frequency stabilization. Dipole moments determined from some individual rotational transitions in the ground and ν₂ vibrational states are, in Debye, with uncertainties in parentheses,

     

140.

Mesoporous Magnetic Materials Based on Rare Earth Oxides     

Yada M  Kitamura H  Ichinose A  Machida M  Kijima T 《Angewandte Chemie (International ed. in English)》1999,38(23):3506-3510

A novel family of mesoporous oxides of rare earth metals (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized with specific surface areas of 253-348 m(2) g(-1) and pore diameters of 2.5-3.0 nm (see Scheme). The mesoporous solids and their surfactant mesophase precursors are paramagnetic and exhibit a magnetic anomaly due to the mesostructured atomic arrangement.     

[首页] « 上一页 [9] [10] [11] [12] [13] 14 [15] [16] [17] [18] [19] 下一页 » 末  页»

Transition		G.S.		$\text{ν}{}_2$		δμ
110 ← 111		2.3315 (1)		2.3472 (1)		0.0157 (1)
211 ← 212		2.3313 (1)		2.3471 (1)		0.0158 (1)
312 ← 313		2.3313 (1)		2.3470 (1)		0.0157 (1)
826 ← 827		2.3311 (1)		2.3466 (1)		0.0155 (1)
927 ← 928		—		2.3466 (1)		—

Mesoporous Magnetic Materials Based on Rare Earth Oxides

A novel family of mesoporous oxides of rare earth metals (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized with specific surface areas of 253-348 m(2) g(-1) and pore diameters of 2.5-3.0 nm (see Scheme). The mesoporous solids and their surfactant mesophase precursors are paramagnetic and exhibit a magnetic anomaly due to the mesostructured atomic arrangement.