Mostrando recursos 1 - 3 de 3

  1. Diagnostic Tests of Cross-section Independence for Limited Dependent Variable Panel Data Models

    Hsiao, Cheng; 肖政; Pesaran, M. Hashem; Pick, Andreas
    This article considers the problem of testing for cross-section independence in limited dependent variable panel data models. It derives a Lagrangian multiplier (LM) test and shows that in terms of generalized residuals of Gourieroux (1987) it reduces to the LM test of Breusch and Pagan (1980). Because of the tendency of the LM test to over-reject in panels with large N (cross-section dimension), we also consider the application of the cross-section dependence test (CD) proposed by Pesaran (2004). In Monte Carlo experiments it emerges that for most combinations of N and T the CD test is correctly sized, whereas the...
    - 19-abr-2013

  2. A comparative study on the electrochemical properties of ring-substituted polyanilines

    Lizong Dai; 戴李宗; Yiting Xu; Yunyou He; Jean-Yves Gal; Huihuang Wu; 吴辉煌
    The redox behavior of polyanilines with ring-substituted groups synthesized by chemical polymerization, poly-2,5-dimethoxyaniline (PDMAn), poly-m-chloroaniline (PmClAn) and poly-o-toluidine (POT), was studied and the morphology and crystal orientation of platinum particles deposited on these polymer membranes was compared. The oxidation of isopropanol on platinized polyaniline-modified electrodes as a model reaction was also investigated to examine the electrocatalytic properties of the polymers. The results show that the first oxidation potential of the polymers increases in the following sequence: PDMAn, POT and then PmClAn, which can be explained in terms of the electronic and steric effects of ring-substituted groups. The growth of Pt...
    - 12-nov-2011

  3. Synthesis and SERS characterization of silver nanocubes

    ZHOU Hai-hui; 周海辉; WU De-yin; 吴德印; HU Jian-qiang; 胡建强; TIAN Zhong-qun; 田中群
    Silver nanocubes were synthesized by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) based on the report by Xia's group. Silver nanocubes were immobilized on silicon wafers by self-assembly processes. SERS activity of silver nanocubes was detected by using pyridine and SCN- respectively as probe molecules. The preliminary results show that the Raman intensities of pyridine and SCN- adsorbed at silver nanocubes were enhanced considerably, indicating that silver nanocubes can be used as a good SERS substrate. On the other hand, SERS combined with the probe molecule method can be used to characterize the optical property...
    - 11-nov-2011

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