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Gold (Au) nanocap arrays and hollow gold nanocap particles were prepared by dip-coating technique combined with wet chemical reduction method, and followed by sonication and dissolution of the silica colloidal template. The surface morphologies and optical properties of the obtained samples were characterized by scanning electron microscopy, transmission electron microscope, and ultraviolet-visible spectrophotometer, respectively. Gold nanocap arrays and hollow gold nanocap particles were used as substrates to detect the surface-enhanced Raman scattering spectra of malachite green and methylene blue (MB), respectively. It was found that the gold nanocap arrays had higher enhancement ability than hollow gold nanocap particles, with enhancement factor of 1.3 × 105and 3.5 × 103, respectively. In addition, gold nanocap arrays exhibited excellent reproducibility with a relative standard deviation of less than 5% and about 10% across a single substrate and between different substrates, respectively. The minimum detection limit for MB adsorbed on hollow gold nanocap particles was down to 0.01 µM. [ABSTRACT FROM AUTHOR]

Phenolic resin (PF) and molybdic acid–modified phenolic (Mo-PF) have been synthesized and developed and combined with polyfluo wax (PFW) to fabricate PF-PFW and Mo-PF-PFW composite coatings. The effects of applied load and sliding speed on the tribological properties of the phenolic composite coating were evaluated using a block-on-ring wear tester. Compared to the PF composite coating, the Mo-PF displayed a lower friction coefficient and a higher wear life under all tested conditions. Scanning electron microscope (SEM) investigation showed that the Mo-PF composite coating had a smooth worn surface after the friction test, and a continuous and uniform transfer film was formed on the surface of the counterpart ring. The improved tribological properties of Mo-PF composite coating resulted from its enhanced thermal properties. [ABSTRACT FROM PUBLISHER]

Colloidal silver nanoparticles were prepared by a simple chemical reduction method. The effect of L-cysteine on the surface-enhanced Raman scattering activity of colloidal silver nanoparticles was investigated by using malachite green as a probe molecule. It was found that the surface-enhanced Raman scattering activity of colloidal silver nanoparticles was improved tremendously with the help of L-cysteine. The possible reasons for this enhancement effect were given. Specifically, in silver colloidal solution, no surface-enhanced Raman scattering spectrum of malachite green was observed at a relatively low concentration (≤2.5 × 10−5 mol/L). However, well-resolved and high-quality surface-enhanced Raman scattering spectra of malachite green were successfully obtained after the addition of L-cysteine to silver colloids, and the minimum detection limit for malachite green was down to 10−8 mol/L. [ABSTRACT FROM AUTHOR]