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Road dust, paint and garden soil are important sources of particulate lead in household dust, according to a study that identified over 8300 separate lead sources. A scanning electron microscope was used to analyze lead content of particles collected from such sources as garden soils, roads and waste incinerators. The amount of lead from each source is dependent on particulate size.

Synchrotron-based X-ray diffraction (XRD) techniques were employed to carry out in situ studies on the growth and evolution of platinum nanocrystals in solution. The platinum nanocrystals in the high-concentration reaction were observed to form branched structures and grow at much greater rates under a kinetically controlled regime.

Wereport a real time investigation into the effect of seed ageon the growth of gold nanorods using a microfluidic reaction apparatus.Through small-angle X-ray scattering (SAXS) and ultraviolet–visiblespectroscopy (UV–vis) analysis, we observe the seeds agingin accordance with Ostwald ripening. A seed solution is then agedin situ and continuously injected into a microfluidic chip to initiaterod growth. We track nanorod formation in real time using in-lineultraviolet–visible and near-infrared (UV–vis–NIR)monitoring and observe a dramatic decrease in yield with increasingseed age. We then demonstrate that, by diluting the gold seed solutionimmediately following synthesis, the rate of aging can be reducedand nanorods synthesized continuously, in good yield. These findingssuggest ultrasmall, catalytically active seeds, which are rapidlylost due to ripening and are critical for the formation of gold nanorods. [ABSTRACT FROM AUTHOR]

Recent successes in forming different shaped face centered cubic (fcc) metal nanostructures has enabled a greater understanding of nanocrystal growth mechanisms. Here we extend this understanding to the synthesis of hexagonally close packed (hcp) metal nanostructures, to form uniquely faceted ruthenium nanocrystals with a well-defined hourglass shape. The hourglass nanocrystals are formed in a three-step thermodynamic growth process with dodecylamine as the organic stabilizer. The hourglass nanocrystals are then shown to readily self-assemble to form a new type of nanocrystal superlattice. [ABSTRACT FROM AUTHOR]

In situ studies on the growth and evolution of platinum nanocrystals in solution were carried out using synchrotron-based X-ray diffraction (XRD) techniques. Ex situ low- and high-resolution transmission electron microscopy (TEM) were used to investigate the nanocrystal morphologies through the different growth stages. In a reaction with low precursor concentration, both XRD and TEM results show that growth occurs at a relatively slow rate and yields faceted morphologies, which are characteristic of a thermodynamically controlled regime. In contrast, the platinum nanocrystals in the high-concentration reaction form branched structures and grow at much greater rates under a kinetically controlled regime. Additionally the growth mechanism of the high-concentration reaction involves a morphology transformation from octapod-like shapes to porous nanostructures, which is brought about by a novel mechanism involving selective growth and etching processes that occur simultaneously and at comparable rates. [ABSTRACT FROM AUTHOR]