Synthesis and crystal structure of a polymeric erbium(III)-sodium(I) coordination complex of picolinic acid N-oxide

A new Er(III)-Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O)(6)(NO3)](NO3). 3.5H(2)O (HL = picolinic acid N-oxide) has been synthesized and characterized by single-crystal X-ray analysis. Crystals are triclinic, P (1) over bar with a = 9.823(2), b = 12.453(2), c = 20.643(4) Angstrom; alpha = 98.49(3), beta = 101.40(3), gamma = 108.69(3)degrees; V = 2284(1) Angstrom(3); Z = 2. Of the two independent eight-coordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelating L ligand, four aqua ligands and two anti-carboxylate oxygen atoms from two neighboring [ErL4] units. The sodium(I) ion is in a distorted octahedral environment, being coordinated by a unidentate nitrate anion, three aqua ligands and two anti-carboxylate oxygen atoms from two adjacent [ErL4] units. The complex is built from zigzag chains of syn-anti carboxylate-bridged erbium(III) moieties directed in the a direction, which are cross-linked pairwise by aqua-bridged dimeric sodium(I) units. The resulting composite polymeric chains are further connected by hydrogen bonds to form a three-dimensional network.

Hydrothermal synthesis and structural characterization of a novel organic-inorganic hybrid compound {[Cu(2, 2 '-bpy)(2)](2)-Mo8O26}

A novel organic-inorganic hybrid compound {[Cu (2, 2'-bpy)(2)](2)Mo8O26} has been hydrothermally Synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group, Pna2(1), with a=2.4164 (5), b=1.8281 (4), c=1.1877 (2) nm, V=5.247(2) nm(3), Z=4, and final R-1=0.0331, wR(2)=0.0727. The structure consists of discrete {[Cu(2,2'-bpy)(2)](2)Mo8O26} clusters, constructed from a beta -octamolybdate subunit[Mo8O26](4-) covalently bonded to two [Cu(2,2'-bpy)(2)](2+) coordination complex cations via bridging oxo groups. In addition, the spectroscopic properties and thermal behavior of this compound have been investigated by spectroscopic techniques (UV-vis, IR, Raman and EPR spectra) and TG analysis.

复杂介质边界元法数值模拟研究

A major impetus to study the rough surface and complex structure in near surface model is because accuracy of seismic observation and geophysical prospecting can be improved. Wave theory study about fluid-satuated porous media has important significance for some scientific problems, such as explore underground resources, study of earth's internal structure, and structure response of multi-phase porous soil under dynamic and seismic effect. Seismic wave numerical modeling is one of the effective methods which understand seismic propagation rules in complex media. As a numerical simulation method, boundary element methods had been widely used in seismic wave field study. This paper mainly studies randomly rough surface scattering which used some approximation solutions based on boundary element method. In addition, I developed a boundary element solution for fluid saturated porous media. In this paper, we used boundary element methods which based on integral expression of wave equation to study the free rough surface scattering effects of Kirchhoff approximation method, Perturbation approximation method, Rytov approximation method and Born series approximation method. Gaussian spectrum model of randomly rough surfaces was chosen as the benchmark model. The approximation methods result were compared with exact results which obtained by boundary element methods, we study that the above approximation methods were applicable how rough surfaces and it is founded that this depends on and ( here is the wavenumber of the incident field, is the RMS height and is the surface correlation length ). In general, Kirchhoff approximation which ignores multiple scatterings between any two surface points has been considered valid for the large-scale roughness components. Perturbation theory based on Taylor series expansion is valid for the small-scale roughness components, as and are .Tests with the Gaussian topographies show that the Rytov approximation methods improves the Kirchhoff approximation in both amplitude and phase but at the cost of an extra treatment of transformation for the wave fields. The realistic methods for the multiscale surfaces come with the Born series approximation and the second-order Born series approximation might be sufficient to guarantee the accuracy of randomly rough surfaces. It could be an appropriate choice that a complex rough surface can be divided into large-, medium-, and small-scale roughness components with their scattering features be studied by the Kirchhoff or Rytov phase approximations, the Born series approximation, and the perturbation theory, respectively. For this purpose, it is important to select appropriate parameters that separate these different scale roughness components to guarantee the divided surfaces satisfy the physical assumptions of the used approximations, respectively. In addition, in this paper, the boundary element methods are used for solving the porous elastic wave propagation and carry out the numerical simulation. Based on the fluid-saturated porous model, this paper analyses and presents the dynamic equation of elastic wave propagation and boundary integral equation formulation of fluid saturated porous media in frequency domain. The fundamental solutions of the elastic wave equations are obtained according to the similarity between thermoelasticity and poroelasticity. At last, the numerical simulation of the elastic wave propagation in the two-phase isotropic media is carried out by using the boundary element method. The results show that a slow quasi P-wave can be seen in both solid and fluid wave-field synthetic seismograms. The boundary element method is effective and feasible.

Molybdenum containing surface complex for olefin epoxidation

Silica-supported molybdenum surface complexes were prepared by the reaction between (N=) Mo(OtBu)(3) and silica via displacement of the tert-butoxy ligands for siloxyls from the silica surface. The structure of the surface molybdenum complexes was well defined by in-situ FT-IR, elemental analysis, H-1 NMR and C-13 CP/MAS NMR techniques. The surface complexes could undergo alcoholysis reaction with CD3OD and CH3OH in the same way as free (N =) Mo(OtBu)(3) and they show high catalytic activity and selectivity in olefin epoxidation. Initial rates up to 24.9 mmol epoxide (mmol Mo)(-1) min(-1) were achieved in the epoxidation of cyclohexene using TBHP as oxidant.

Spatial variability in water quality and surface sediment diatom assemblages in a complex lake basin,lake of the woods,ontario,canada

Lake of the Woods (LOW) is an international waterbody spanning the Canadian provinces of Ontario and Manitoba, and the U.S. state of Minnesota. In recent years, there has been a perception that water quality has deteriorated in northern regions of the lake, with all increase in the frequency and intensity of toxin-producing cyanobacterial blooms. However, given the lack of long-term data these trends are difficult to verify. As a first step, we examine spatial and seasonal patterns in water quality in this highly complex lake on the Canadian Shield. Further, we examine surface sediment diatom assemblages across multiple sites to determine if they track within-take differences in environmental conditions. Our results show that there are significant spatial patterns in water quality in LOW. Principal Component Analysis divides the lake into three geographic zones based primarily on algal nutrients (i.e., total phosphorus, TP), with the highest concentrations at sites proximal to Rainy River. This variation is closely tracked by sedimentary diatom assemblages, with [TP] explaining 43% of the variation in diatom assemblages across sites. The close correlation between water quality and the surface sediment diatom record indicate that paleoecological models could be used to provide data on the relative importance of natural and anthropogenic sources of nutrients to the lake.

Kinetic analysis of TNF immune complex by using surface plasmon resonane

The kinetic analysis of the interaction between tumor necrosis factor(TNF) and its monoclonal antibody was performed by surface plasmon resonance(SPR) technique. The monoclonal antibody was immobilized to the surface of CM5 sensor chip by amine coupling. TNF at different concentrations was injected across the mAb immobilized surface. The interaction was recorded in real time and could be seen on the sensorgram. One cycle, including association, dissociation and regeneration, lasted no more than 15 min. The interaction results was evaluated using 1 : 1 Langmuir binding model. The kinetic rate constants were calculated to be: k =1.68 X 10(3) L (.) mol(-1) (.) s(-1), k(d) = 1.73 X 10(-4) s(-1), and the affinity constants K-A = 9. 7 X 10(3) L (.) mol(-1), K-r)= 1. 03 X 10(-7) Mol (.) L-1. The X-2 was 3.47, which showed that the interaction is consistent with the 1 : I model. We can see from the results that although there are two binding sites in one mAb molecule, TNF reacts with each site in an independent and noncooperative manner.

Metal ion and anion coordination in the thiamine-[Pt-II(NO2)(4)](2-) system. Structures of a metal complex, Pt(thiamine)(NO2)(3), and two salts, (H-thiamine)[Pt(NO2)(4)]center dot 2H(2)O and (thiamine monophosphate)(2)[Pt(NO2)(4)]center dot 2H(2)O

Reaction of thiamine or thiamine monophosphate (TMP) with K2Pt(NO2)(4) afforded a metal complex, Pt(thiamine)(NO2)(3) (1), and two salt-type compounds, (H-thiamine)[Pt(NO2)(4)]. 2H(2)O (2) and (TMP)(2)[Pt(NO2)(4)]. 2H(2)O (3), which were structurally characterized by X-ray diffraction. In 1, the square-planar Pt2+ ion is coordinated to the pyrimidine N(1'), a usual metal-binding site, and three NO2- groups. The thiamine molecule exists as a monovalent cation in 1 and a divalent cation in 2 while the TMP molecule is a monovalent cation in 3. In each compound, thiamine or TMP adopts the usual F conformation and forms two types of host-guest-like interactions with anions, which are of the bridging forms, C(2)-H . . . anion . . . pyrimidine-ring and N(4'1)-H(...)anion(...)thiazolium-ring. In 3, there is an additional anion-bridging interaction between the pyrimidine and thiazolium rings of TMP, being of the form C(6')-H . . . anion . . . thiazolium-ring. The salts 2 and 3 show similar hydrogen-bonded cyclic dimers of thiamine or TMP between which the anions are held. Results are compared with those of the other thiamine-platinum complexes. (C) 2001 Elsevier Science B.V. All rights reserved.

Enhanced surface plasmon resonance immunosensing using a streptavidin-biotinylated protein complex

In this paper, we present a novel strategy for improving the sensitivity of surface plasmon resonance immunosensing using a streptavidin-biotinylated protein complex. This amplification strategy is based on the construction of a molecular complex between streptavidin and biotin labeled protein. The complex can be formed in a cross-linking network of molecules so that the amplification of the response signal will be realized due to the big molecular size of the complex. The results show that the amplification strategy causes a dramatic improvement of the detection sensitivity. hIgG protein could be detected in the range of 0.005-10 mug ml(-1).

ELECTROOXIDATION OF A CHLORIDE COMPLEX OF PLATINUM(II) AT A GLASSY-CARBON ELECTRODE

The electro-oxidation of PtCl42- was studied on a glassy carbon (GC) electrode. A Pt(IV) complex was formed on the electrode surface through coordination to the oxygen atom of an oxide functional group on the electrode, which results in its deactivation. The ferri/ferrocyanide redox couple was used as a probe to examine the activity of the GC electrode. X-ray photoelectron spectroscopy was employed to characterize the platinum on the electrode surface, and showed that the oxidation state of the Pt element changes depending on the electrochemical treatment of GC electrode. The platinum complex on the surface of the GC electrode can be transformed to Pt-0 by cycling the electrode between -0.25 and +1.65 V/SCE in 0.1 M H2SO4 solution. The above procedure can be used to disperse platinum ultramicroparticles on the surface of a GC electrode.

NMR-STUDIES ON THE COORDINATION OF RARE-EARTHS WITH GLYCYL-DL-VALINE AND THE CONFORMATION OF THEIR COMPLEX IN AQUEOUS-SOLUTION

In this paper lanthanide-induced shifts have been measured for C-13 and H-1 nuclei of glycyl-DL-valine in the presence of three lanthanide cations (La3+, Ho3+ and Yb3+) in aqueous solution. The stability constants of the coordination compounds of rare earths (Ho, Yb) with glycyl-DL-valine have been calculated. The coordination of rare earths with the ligand has been discussed. The simulation for conformation of lanthanide coordination compounds with glycyl-DL-valine shows that the ligand is coordinated to lanthanide ion through oxygen atoms of carboxyl group and the bond length of Ln-O is 0.226 nm. In the coordination compounds glycyl-DL-valine is in extended state with minimal steric hindrance.

Instability Analysis of Nonlinear Surface Waves in a Circular Cylindrical Container Subjected to a Vertical Excitation

Singular perturbation theory of two-time scale expansions was developed both in inviscid and weak viscous fluids to investigate the motion of single surface standing wave in a liquid-filled circular cylindrical vessel, which is subject to a vertical periodical oscillation. Firstly, it is assumed that the fluid in the circular cylindrical vessel is inviscid, incompressible and the motion is irrotational, a nonlinear evolution equation of slowly varying complex amplitude, which incorporates cubic nonlinear term, external excitation and the influence of surface tension, was derived from solvability condition of high-order approximation. It shows that when forced frequency is low, the effect of surface tension on mode selection of surface wave is not important. However, when forced frequency is high, the influence of surface tension is significant, and can not be neglected. This proved that the surface tension has the function, which causes free surface returning to equilibrium location. Theoretical results much close to experimental results when the surface tension is considered. In fact, the damping will appear in actual physical system due to dissipation of viscosity of fluid. Based upon weakly viscous fluids assumption, the fluid field was divided into an outer potential flow region and an inner boundary layer region. A linear amplitude equation of slowly varying complex amplitude, which incorporates damping term and external excitation, was derived from linearized Navier-Stokes equation. The analytical expression of damping coefficient was determined and the relation between damping and other related parameters (such as viscosity, forced amplitude and depth of fluid) was presented. The nonlinear amplitude equation and a dispersion, which had been derived from the inviscid fluid approximation, were modified by adding linear damping. It was found that the modified results much reasonably close to experimental results. Moreover, the influence both of the surface tension and the weak viscosity on the mode formation was described by comparing theoretical and experimental results. The results show that when the forcing frequency is low, the viscosity of the fluid is prominent for the mode selection. However, when the forcing frequency is high, the surface tension of the fluid is prominent. Finally, instability of the surface wave is analyzed and properties of the solutions of the modified amplitude equation are determined together with phase-plane trajectories. A necessary condition of forming stable surface wave is obtained and unstable regions are illustrated. (c) 2005 Elsevier SAS. All rights reserved.

Effect of surface tension on the mode selection of vertically excited surface waves in a circular cylindrical vessel

Singular perturbation theory of two-time-scale expansions was developed in inviscid fluids to investigate patternforming, structure of the single surface standing wave, and its evolution with time in a circular cylindrical vessel subject to a vertical oscillation. A nonlinear slowly varying complex amplitude equation, which involves a cubic nonlinear term, an external excitation and the influence of surface tension, was derived from the potential flow equation. Surface tension was introduced by the boundary condition of the free surface in an ideal and incompressible fluid. The results show that when forced frequency is low, the effect of surface tension on the mode selection of surface waves is not important. However, when the forced frequency is high, the surface tension cannot be neglected. This manifests that the function of surface tension is to cause the free surface to return to its equilibrium configuration. In addition, the effect of surface tension seems to make the theoretical results much closer to experimental results.

Vertically forced surface wave in weakly viscous fluids bounded in a circular cylindrical vessel

Two-time scale perturbation expansions were developed in weakly viscous fluids to investigate surface wave motions by linearizing the Navier-Stokes equation in a circular cylindrical vessel which is subject to a vertical oscillation. The fluid field was divided into an outer potential flow region and an inner boundary layer region. A linear amplitude equation of slowly varying complex amplitude, which incorporates a damping term and external excitation, was derived for the weakly viscid fluids. The condition for the appearance of stable surface waves was obtained and the critical curve was determined. In addition, an analytical expression for the damping coefficient was determined and the relationship between damping and other related parameters (such as viscosity, forced amplitude, forced frequency and the depth of fluid, etc.) was presented. Finally, the influence both of the surface tension and the weak viscosity on the mode formation was described by comparing theoretical and experimental results. The results show that when the forcing frequency is low, the viscosity of the fluid is prominent for the mode selection. However, when the forcing frequency is high, the surface tension of the fluid is prominent.