Four Ln(III) coordination polymers, {[Ln2(1,3-bdc)3(H2O)4]·DMF·H2O}n (Ln = Sm 1, Eu 2) and [Ln2(mal)3(H2O)6]n (Ln = Sm 3, Eu 4) (1,3-H2bdc = isophthalate acid, H2mal = malonate acid), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra, UV–Vis–NIR absorption spectra, and fluorescence spectra. The structural analyses reveal that polymer 1 is a 3D coordination polymer. Its asymmetry unit contains two crystallographically independent Sm(III) ions, both are eight-coordinated. The 1,3-bdc2? anions show three different coordination modes. The structure of polymer 2 is isomorphous with that of 1. Polymer 3 is also a 3D coordination polymer, its asymmetry unit contains one Sm(III) ion, which is nine-coordinate. The mal2? anions have two different coordination modes. The structure of polymer 4 is isomorphous with that of 3. The luminescent study shows that polymers 1, 2, and 4 exhibit characteristic emission bands in the visible region, corresponding to the transitions of the Ln(III) ions. By comparison and analysis of luminescence, it is found that the incidence of the same ligand on the corresponding spectra of different Ln(III) ions is different, and the influence of different ligands on luminescence of the same Ln(III) ion is also very different.
The sorption of UO22+ from aqueous solution on attapulgite was investigated as a function of contact time, solid content, pH, ionic strength, foreign ions, humic acid (HA), and fulvic acid (FA) under ambient conditions by using batch technique. The attapulgite sample was characterized by XRD and FTIR in detail. The results indicated that the sorption of UO22+ was strongly dependent on pH and ionic strength. The sorption of UO22+ on attapulgite increased quickly with rising pH at pH < 6.5, and decreased with increasing pH at pH > 6.5. The presence of HA or FA enhanced the sorption of UO22+ on attapulgite obviously at low pH because of the strong complexation of surface adsorbed HA/FA with UO22+ on attapulgite surface. Sorption of UO22+ on attapulgite was mainly dominated by ion-exchange or outer-sphere surface complexation at low pH values, but by inner-sphere surface complexation at high pH values. The results indicate that attapulgite is a very suitable adsorbent for the preconcentration and solidification of UO22+ from large volumes of aqueous solutions because of its negative surface charge and large surface areas. 相似文献
2,3‐Dimethylpentacene (DMP) and 2,3‐dimethyltetracene (DMT) were synthesized, characterized and employed as the channel material in the fabrication of thin‐film transistors. The two methyl groups increase the chemical stability of the compounds versus the pristine acene analogues. The crystals maintain herringbone‐like molecular packing, whereas the weak dipole associated with the unsymmetrical molecule induces an anti‐parallel alignment among the neighbors. This structural motif favors layered film growth on SiO2/Si surface. Thin film transistors prepared on SiO2/Si and n‐nonyltrichlorosilane‐modified SiO2/Si at different substrate temperatures were compared. DMP‐based transistors prepared on rubbed n‐nonyltrichlorosilane‐modified SiO2/Si substrate gave the highest field‐effect mobility of 0.46 cm2/Vs, whereas DMT‐based transistor gave a mobility of 0.028 cm2/Vs. 相似文献
A new cyclopentanone derivative, (1'R,5'R)-5-(5'-carboxymethyl-2'-oxocyclopentyl)-3Z-pentenyl acetate (1), was isolated from Euphorbia hirta. Its structure was elucidated on the basis of spectroscopic analysis including 1D and 2D NMR techniques. The EtOAc extract of Euphorbia hirta was evaluated against K562 and A549 cancer cell lines. 相似文献
The purpose of this paper is to present an iterative scheme for finding a common element of the set of solutions to the variational inclusion problem with multivalued maximal monotone mapping and inverse-strongly monotone mappings and the set of fixed points of nonexpansive mappings in Hilbert space.Under suitable conditions, some strong convergence theorems for approximating this common elements are proved. The results presented in the paper not only improve and extend the main results in Korpelevich(Ekonomika i Matematicheskie Metody,1976,12(4):747-756),but also extend and replenish the corresponding results obtained by Iiduka and Takahashi(Nonlinear Anal TMA,2005,61(3):341-350),Takahashi and Toyoda(J Optim Theory Appl,2003, 118(2):417-428),Nadezhkina and Takahashi(J Optim Theory Appl,2006,128(1):191- 201),and Zeng and Yao(Taiwanese Journal of Mathematics,2006,10(5):1293-1303). 相似文献
Making use of the relativistic BBGKY technique,the relativistic generalization of Landau collision integral is botained.Furthermore,we calculate the relativistic hydrodynamic modes up to the second order in the hydrodynamic wave number.Combining Resibois‘ method,we present the first principle formula of the relativistic heat conductivity of Coulumb electronic plasmas for low-order corrections. 相似文献
Random wavelet expansion is introduced in the study of stationary self-similar generalized random fields. It is motivated
by a model of natural images, in which 2D views of objects are randomly scaled and translated because the objects are randomly
distributed in the 3D space. It is demonstrated that any stationary self-similar random field defined on the dual space of
a Schwartz space of smooth rapidly decreasing functions has a random wavelet expansion representation. To explicitly construct
stationary self-similar random fields, random wavelet expansion representations incorporating random functionals of the following
three types are considered: (1) a multiple stochastic integral over the product domain of scale and translate, (2) an iterated
one, first integrating over the scale domain, and (3) an iterated one, first integrating over the translate domain. We show
that random wavelet expansion gives rise to a variety of stationary self-similar random fields, including such well-known
processes as the linear fractional stable motions.
Received: 11 December 1998 / Revised version: 31 January 2001 / Published online: 23 August 2001 相似文献