Simultaneous determination of catecholamines and amino acids by micellar electrokinetic chromatography with laser-induced fluorescence detection

A selective and sensitive method was developed for separation and simultaneous determination of catecholamines and amino acids by MEKC with LIF. Interestingly enough, such work has been firstly performed on catecholamines derivatized with 4-chloro-7-nitro-2,1,3-benzoxadiazole and the detailed derivatization mechanism was discussed. After derivatization at 60 degrees C for 20 min, NBD-labeled catecholamines and amino acids were separated in a buffer system containing 10 mM sodium tetraborate-Na2HPO4, 20 mM SDS, and 10% v/v ACN at pH 9.75. SDS micelles were employed to improve the fluorescence intensity of catecholamine derivatives efficiently. Under optimum conditions, two catecholamines and 11 amino acids were separated in a short 13 min analysis time and the RSDs for migration time and peak area were less than 0.60 and 6.50%, respectively. The method was successfully applied for the quantification of catecholamines and amino acids in Portulaca oleracea L., human urine sample, and mixed injection sample.     

Constructions of stable equivalences of Morita type for finite-dimensional algebras III

In this paper, we provide a new method to produce stable equivalencesof Morita type. Our main results can be stated as follows. LetA and B be two finite-dimensional k-algebras over a field k.Suppose that two bimodules _AM_B and _BN_A define a stable equivalenceof Morita type between A and B and that R is a generator forA-modules. Then there is a stable equivalence of Morita typedefined by X and Y between the endomorphism algebra End_A(R)of the module R and the endomorphism algebra End_B(N_AR) of themodule N_AR. If M and N satisfy the property that both (N_A–,M_B–) and (M_B–, N_A–) are adjoint pairs of functors,then so do the modules X and Y. Moreover, we show that the self-injectivedimension and the Gorenstein property are invariant under stableequivalences of Morita type with the above-mentioned adjointproperty.     

苯基氯化钕(Ⅱ)的合成及其对双烯烃聚合的催化活性

Kalbunde,Graves,Skell,用热原子蒸汽法曾将氯代苯分别与钒、铬、钼反应,得到了夹心型化合物:(C₆H₅Cl)₂V,(C₆H₅Cl)₂Cr,(C₆H₅Cl)₂Mo;Kla-bunde及Shell用钯及镁与氯代苯反应得格氏试剂型化合物:C₆H₅PdCl及C₆H₅-MgCl。不同金属与氯代苯反应,却得到两种不同类型的化合物。     

浓甲醛水溶液催化聚合动力学

在饱和或过饱和的浓甲醛水溶液中,在离子型催化剂作用下的甲醛聚合难以用缩聚机理解释的情况下,我们提出了离子型聚合机理。     

Fabrication of a Metal Particle Array Based on a Self‐Assembled Template from a Two‐Armed Polymer

A two‐armed polymer with a crown ether core self‐assembles to produce macroporous films with pores perpendicularly reaching through the film down to the substrate. A possible assembling mechanism is discussed. The pore size can be conveniently adjusted by changing the solution concentration. These through‐hole macroporous films provide a template for fabricating an array of Cu nanoparticle aggregates.

     

Highly Dispersed and Small‐Sized Nickel(II) Hydroxide Co‐Catalyst Prepared by Photodeposition for Hydrogen Production

Photodeposition has been widely used as a mild and efficient synthetic method to deposit co‐catalysts. It is also worth studying how to synthesize non‐noble metal photocatalysts with uniform dispersion. Different synthetic conditions in photodeposition have a certain influence on particle size distribution and photocatalytic activity. Therefore, we designed experiments to prepare the inexpensive composite photocatalyst Ni(OH)₂/g‐C₃N₄ by photodeposition. The Ni(OH)₂ co‐catalysts disperse uniformly with particle sizes of about 10 nm. The photocatalytic hydrogen production rate of Ni(OH)₂/g‐C₃N₄ reached about 19 mmol g^?1 h^?1, with the Ni(OH)₂ deposition amount about 1.57 %. During 16 h stability testing, the rate of hydrogen production did not decrease significantly. The composite catalyst also revealed a good hydrogen production performance under sunlight. The Ni(OH)₂ co‐catalyst enhanced the separation ability of photogenerated carriers, which was proved by surface photovoltage and fluorescence analysis.     

The low temperature synthesis of Euand Dy activated Sr3Al2O6 nanophosphors by microwave method

The Eu²⁺and Dy³⁺ activated Sr₃Al₂O₆ (S3A2O-ED) nanophosphors were synthesized by a new microwave method. The S3A2O-ED sample calcined in microwave oven at around 650 °C for 20 min possesses a cubic Sr₃Al₂O₆ single phase. The sample showed small size (80–100 nm) and spherical shape. The excitation and emission spectra indicated that excitation broad band chiefly sited in visible range and the nanophosphors emitted strong light at 611 nm under around 473 nm excitation. Comparing with conventional method, the microwave synthesis of S3A2O-ED greatly decreased the calcining temperature and time. However, the brightness of S3A2O-ED nanophosphors was reduced. The change of luminescent intensity in S3A2O-ED nanophosphors could be attributed to the effect of surface energy.     

Experimental study of the preparation of targeted microbubble contrast agents carrying urokinase and RGDS

Purpose

To explore the feasibility and the best combined proportion of the preparation of targeted and thrombolytic contrast agents carrying urokinase (UK) and Arg-Gly-Asp-Ser (RGDS), and to study its effect of thrombolysis in vitro.

Methods

Urokinase and RGDS were combined to the surface of SonoVue by direct conjugation method. According to the different ratio of urokinase and RGDS when mixed, they were divided into three groups whose urokinase/RGDS were 1:1, 2:1 and 1:2, respectively. To measure the binding rate of microbubbles and urokinase as well as RGDS by flow cytometry. To detect the effect of thrombolysis by thrombolytic experiment in vitro. To detect the targeting effects by experiment in vivo.

Results

The results of flow cytometry detection showed that the binding rates of urokinase and RGDS of three groups were, respectively, 73.4 ± 11.0% and 67.1 ± 10.9%, 8.8 ± 7.2% and 7.8 ± 6.9%, 49.7 ± 21.3% and 45.9 ± 21.7% after standing for 2 h. In vitro thrombolysis experiment indicated that the urokinase had activity in the prepared contrast agent which the binding rates of urokinase and RGDS were the highest. And it was injected intravenous, the contrast agent aggregated on the surface of the thrombus of the rabbit femoral arterial. The thrombus emitted fluorescence.

Conclusions

The binding rate of the targeted contrast agent prepared by 1:1 of urokinase/RGDS was the highest. It had thrombolysis ability in vitro, and it had thrombo-targeting effect in vivo.     

Surface profile measurement of moving objects by using an improved π phase-shifting Fourier transform profilometry

The π phase-shifting Fourier transform technique is introduced into the surface profile measurement of moving objects. A digital grating comprising two regions, which have a π phase shifting is projected onto the object. Two line-scan CCD cameras are used to capture two deformed fringe patterns with π phase shifting at the same time. As the object is moving, each point at the object surface can be captured twice. The digital correlation method is used to calibrate the experimental system. The zero-order component can be eliminated by subtracting intensities of the same surface point in two captured images. And then the phase can be extracted by Fourier transform without the disturbance of zero-order component. Experimental results demonstrate that this method is feasible for the moving surface profile detection and the measurable slope of height variation can be extended.     

Global existence and asymptotic behavior for the compressible Navier–Stokes equations with a non‐autonomous external force and a heat source

In this paper, we prove the global existence and asymptotic behavior, as time tends to infinity, of solutions in Hⁱ (i=1, 2) to the initial boundary value problem of the compressible Navier–Stokes equations of one‐dimensional motion of a viscous heat‐conducting gas in a bounded region with a non‐autonomous external force and a heat source. Some new ideas and more delicate estimates are used to prove these results. Copyright © 2008 John Wiley & Sons, Ltd.