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321.
Gen-ichi Oshikiri 《manuscripta mathematica》2001,104(4):527-531
In this paper, we extend a result by H. Takagi on the non-existence of mutually commuting and linearly independent Killing
vector fields on positively curved Riemannian manifolds. Further, a kind of “Compact Leaf Theorem” is proved for metric foliations
of closed manifolds with positive sectional curvature.
Received: 26 May 2000 / Revised version: 28 February 2001 相似文献
322.
S. Kobayashi T. KimuraS. Takahashi Y. KamadaH. Kikuchi 《Journal of magnetism and magnetic materials》2008
Relationships between minor hysteresis loops and dislocation density have been investigated at various temperatures from 10 to 600 K in polycrystalline nickel with tensile deformation. It was revealed that coefficients obtained from scaling relations between parameters of minor-loops are in linear proportion to stress at all measuring temperatures below its Curie temperature. Considering that dislocation density is generally in proportion to the square root of true stress, it is concluded that the coefficients are related with the square root of dislocation density. This method using minor hysteresis loops is useful for quantitative evaluation of dislocation density because of its very low measurement field. 相似文献
323.
l-Lysine-based hydrogelators can form supramolecular hydrogels over a wide pH range and contain inorganic salts and acids, especially, 3 forms hydrogels containing 1 M HCl and H2SO4 at 1 g/L. 相似文献
324.
1,4,8,11,15,18,22,25-octabutoxyphthalocyanines ((OBu)8Pcs) having eight 2-thienyl (1) and [2,2'-bithiophene]-5-yl (2) groups at beta positions and their zinc(II) and cobalt(II) derivatives were prepared from 2-thienyl- (3) or [2,2'-bithiophene]-5-yl (4)-substituted phthalonitriles in moderate to good yields. The electronic absorption spectra of the Pcs showed red-shifted Q-bands relative to beta-unsubstituted (OBu)8Pcs. The longer substituent, the [2,2'-bithiophene]-5-yl group, is more effective than the 2-thienyl group in enlarging the pi-conjugated system of the Pcs. The ring oxidation potential obtained by cyclic voltammetry shifted cathodically with increasing chain length, indicating destabilization of the HOMOs. Due to the shift of the Q-band, 2-thienyl- and [2,2'-bithiophene]-5-yl-substituted Pcs exhibit a remarkable color change from the original green color. 相似文献
325.
The π → π1 transitions to triplets are shown to be independent of the σ → σ1 transitions if the zero differential overlaps are assumed between the pi- and sigma-orbitals. For the singlet transitions, however, Σ—Π coupling does not vanish, and its inclusion is explicitly depicted. 相似文献
326.
Thermally stimulated currents (TSC) were examined for poly(bis(p-fluorophenoxy)phosphazene) (PBFPP) film. TSC showed peaks at the glass transition temperature (Tg=–4 °C) and atT(1) (160 °C – 170 °C), where-form crystal phase transformed to mesophase of-form structure. Another peak was found atT
cc
betweenTg andT(1). Linear relationship between polarization field and peak current ofT
cc
-peak was found, which shows thatT
cc
-peak was caused by motion of dipolar groups in crystalline phase. When heating (up to 200 °C) and cooling (down to 20 °C) thermal process was repeated,T
cc
-peak shifted to higher temperature region approachingT(1) and simultaneously, the peak current ofT(1)-peak became smaller. Activation energy, time constant of dipolar relaxation and charge mobility were evaluated forT
cc
-peak. From these results, it was concluded that-form and more ordered- form crystalline phases coexisted in PBFPP once heated aboveT(1) and the content of- form phase increased by repeated thermal hysteresis. 相似文献
327.
Takashi Suzuki Toshihiro Hirai Sadao Hayashi 《Reaction Kinetics and Catalysis Letters》1991,43(2):293-299
CO and/or ethylene adsorbed on -Al2O3 was subjected to temperature programmed desorption (TPD). When temperature of the gas adsorbed specimens was linearly raised, two peaks were observed in desorption profile of both ethylene and that of CO. When an equimolecular misture of carbon monoxide and ethylene was adsorbed over the specimen, desorption temperature of CO(H) shifted to high temperature side of 87.2 °C, whereas that of ethylene (H) shifted to low temperature side of 33.0 °C. This behavior of desorption temperature might be attributed to a strong interaction in the two adsorbates induced by an electronic effect.
CO / -Al2O3 . , CO. CO(H) (87, 2°C), (H) (33°C). , .相似文献
328.
Satoru Sasaki Hidetoshi Hirahara Hirokazu Nakayama 《Journal of solid state chemistry》2006,179(4):1129-1135
The intercalation of water-soluble p-sulfonated calix[4 and 6]arene (CS4 and CS6) in the interlayer of the Mg-Al and Zn-Al layered double hydroxide (LDH) by the coprecipitation method has been investigated, as well as the adsorption properties of the resulting CS/LDHs for benzyl alcohol (BA) and p-nitrophenol (NP) to prepare new microporous organic-inorganic hybrid adsorbents. The amount and arrangement of CS intercalated was different by the kind of the host metal ions. CS4 cavity axis was perpendicular for the Mg-Al LDH basal layer and parallel for the Zn-Al LDH basal layer, while CS6 cavity axis was perpendicular for both the LDH basal layers. In the BET surface area measurement, the surface area of the Zn-Al/CS4/LDH was four times than that of the Mg-Al/CS4/LDH, expecting that the former has higher adsorption capacity than the latter. In fact, the adsorption ability of the CS/LDHs for BA and NP in aqueous solution was found to be larger in the Zn-Al/CS4/LDH than in the Mg-Al/CS4/LDH. In addition, the adsorption ability of both the LDHs was larger in the CS6/LDHs than in the CS4/LDHs. These results were explained by the difference in the amount and arrangement of CS intercalated in the LDH interlayer space. 相似文献
329.
Motoyoshiya J Sakai N Imai M Yamaguchi Y Koike R Takaguchi Y Aoyama H 《The Journal of organic chemistry》2002,67(21):7314-7318
The title compound N,N'-bistosyl-1H,4H-quinoxaline-2,3-dione (TsQD) provides peroxyoxalate chemiluminescence (PO-CL) when reacted with hydrogen peroxide in the presence of fluorophores. The chemiluminescence (CL) efficiency of TsQD was superior to that of other related compounds such as bis(2,4,6-trichlorophenyl) oxalate (TCPO), a typical oxalate for the peroxyoxalate PO-CL, under an aqueous condition. Factors affecting the PO-CL efficiency are discussed from the viewpoint of the structures of the substrates and the electronic nature of the fluorophores. A linear correlation of the logarithmic values evaluated from the CL quantum yields with the oxidation potentials of the aromatic fluorophores supports the involvement of the chemically initiated electron exchange luminescence (CIEEL) mechanism in both TsQD- and TCPO-CL systems. Also, an excellent Hammett relationship was derived from the correlation between the sigma(+) values and the relative singlet excitation yields in TsQD-CL enhanced by a series of fluorescent para,para'-disubstituted distyrylbenzenes. 相似文献
330.
The association constant K between methylviologen MV and indoleacetate IA was decreased by the addition of cationic vesicles, and the K increased at high vesicle concen-trations. The influence of the polymerization of surfactants with different chain lengths
on K was different. The concentration dependence of K was analyzed by a theory in terms of the partition coefficients of reactants between the bulk solvent phase and the local
vesicle environment. The theoretical partition coefficients were determined graphically. The measured depen-dence of K on vesicle concentration was satisfactorily reproduced by the theory. When dimyrystyldiallylammonium bromide (DMAB) was added
to the complex, the polymerization of the surfactant increased the partition coefficients of IA and the complex but decreased
that of MV. However, the polymerization of dicetyldiallylammonium bromide (DCAB) showed the reverse tendency. The influence
of polymerization on K or the partition coefficient was discussed in terms of the difference in the polymerization mechanism due to the differences
in the distance between the neighboring nonpolymerized surfactant molecules and the polymerization induced change in that
distance.
Received: 10 May 1996 Accepted: 27 August 1996 相似文献