In this study, we have used a simple seed-mediated synthesis process to prepare uniform Pd nanorods with average lengths of approximately 200 and 300 nm through the addition of 50-100 microL of 0.004 M copper acetate solution into the growth solution for the first time. Because of their long lengths, they nicely settled to the bottom of the reaction vial and can easily be separated from the suspended faceted particles. The nanorods have an average diameter of approximately 20 nm, so they have high aspect ratios of 10-15 or more. They can readily self-assemble into high-density packing structures on substrates. By increasing the volume of the copper acetate solution added to 250 microL, extensively branched Pd nanocrystals were obtained. The crystal structures of both particle morphologies have been examined. The nanorods possess a penta-twinned structure. Different growth directions have been found for the branched nanocrystals. The growth mechanism of these nanostructures was studied in great detail. A mixture of short Pd rods and faceted particles was formed first and elongated into long rods or branched nanocrystals with the assistance of copper atom deposition. A reduction potential of copper lower than that of palladium leads to periodic deposition and reoxidation of copper atoms on the growing rods and faceted particles. Use of other metal ions did not form long nanorods and branched nanocrystals. UV-vis spectra of the 200 nm Pd nanorods showed a significant absorption band in the near-infrared region with band maximum at approximately 1800 nm, while the 300 nm rods have band maxima of 2000-2100 nm. Both the nanorods and branched nanocrystals were found to serve as highly efficient and recyclable catalysts for catalyzing a Suzuki coupling reaction between phenylboronic acid and iodobenzene. They are also thermally stable under the reflux condition and can be easily removed from the product solution. These novel Pd nanostructures should find use in other palladium-catalyzed reactions.

The performance of clinical tests for disease screening is often evaluated using the area under the receiver‐operating characteristic (ROC) curve (AUC). Recent developments have extended the traditional setting to the AUC with binary time‐varying failure status. Without considering covariates, our first theme is to propose a simple and easily computed nonparametric estimator for the time‐dependent AUC. Moreover, we use generalized linear models with time‐varying coefficients to characterize the time‐dependent AUC as a function of covariate values. The corresponding estimation procedures are proposed to estimate the parameter functions of interest. The derived limiting Gaussian processes and the estimated asymptotic variances enable us to construct the approximated confidence regions for the AUCs. The finite sample properties of our proposed estimators and inference procedures are examined through extensive simulations. An analysis of the AIDS Clinical Trials Group (ACTG) 175 data is further presented to show the applicability of the proposed methods. The Canadian Journal of Statistics 38:8–26; 2010 © 2009 Statistical Society of Canada

SUMMARYThe objective of this study is to propose a 2.5D ÿnite=inÿnite element procedure for dealing with the ground vibrations induced by moving loads. Besides the two in-plane degrees of freedom (DOFs) per node conventionally used for plane strain elements, an extra DOF is introduced to account for the outof-plane wave transmission. The proÿle of the half-space is divided into a near ÿeld and a semi-inÿnite far ÿeld. The near ÿeld containing loads and irregular structures is simulated by the ÿnite elements, while the far ÿeld covering the soils extending to inÿnity by the inÿnite elements with due account taken of the radiation e ects for moving loads. Enhanced by the automated mesh expansion procedure proposed previously by the writers, the far ÿeld impedances for all the lower frequencies are generated repetitively from the mesh created for the highest frequency considered. Finally, the accuracy of the proposed method is veriÿed through comparison with a number of analytical solutions.

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