The effective control over the behavior of nanostructured systems requires a tight control over the shape and size of the nanoparticle building blocks. This control can be very effective and useful in the case of crystalline gold nanoparticles. In order to achieve a precise morphology control over the particles obtained using gold nanorods as seeds; we have studied the crystalline structure of the initial single-crystal gold nanorods, which can be used in subsequent overgrowth processes. We also studied the mechanisms involved in the overgrowth and reshaping of such gold nanorods.
Abstract Ultrasonic energy delivered by means of a probe was used to reduce the operation time in each of the stages corresponding to the Tessier sequential extraction procedure when it was applied to metal fractionation in a river sediment. The optimum extraction conditions (amplitude and sonication time) were specifically selected in each step for Cu, Cr, Ni, Pb and Zn. Extractable metal contents obtained in each stage by both the conventional and ultrasonic extraction procedures were measured by Flame-Atomic Absorption Spectrometry and the results were statistically compared (P = 0.95). Although significant differences were found for Cu in the three first stages and for Pb and Zn in the two last stages, the total extractable metal contents obtained for these elements were similar when using both methods. Ni was always quantitatively extracted and Cr was almost not leached using the proposed accelerated extraction scheme.