The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H₂O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface.

Pollution of freshwater ecosystems from polycyclic aromatic hydrocarbons (PAHs) is a global concern. The US Environmental Protection Agency (EPA) has included the PAHs pyrene, phenanthrene, and naphthalene among the 16 priority compounds of special concern for their toxicological effects. The aim of this study was to adapt and characterize a microbial consortium from ore waste with the potential to remove these three PAHs from water. This microbial consortium was exposed to the target PAHs at levels of 5, 10, 20, 50, and 100 mg L⁻¹ for 14 days. PAH bioremoval was measured using the analytical technique of solid phase microextraction, followed by gas chromatography mass spectrometry (SPME-GC/MS). The results revealed that up to 90% of the target PAHs can be removed from water after 14 days at a concentration level of 100 mg L⁻¹. The predominant group of microorganisms identified at the phylum taxonomic level were the Proteobacteria, while the Actinobacteria were the predominant subgroup. The removal of phenanthrene, naphthalene, and pyrene predominantly occurred in specimens of genera Stenotrophomonas, Williamsia, and Chitinophagaceae, respectively. This study demonstrates that the use of specific microorganisms is an alternative method of reducing PAH levels in water.

Apple (Malus domestica Borkh) is an appreciated source of polyphenols. Phenolic compounds are known as natural antioxidants and have a wide range of applications in different industries. Apple pomace has the potential of being an alternative source of polyphenols. To determine the polyphenolic profile of apple pomace, samples from the skin at two different stages of ripening were extracted with 80-20% EtOH-water/acetic acid 5% (S1) and 20-80% EtOH-water/acetic acid 5% (S2) in order to determine the solvent system. Ripe skins extracted with S1 showed a higher total polyphenol content or TPC (1.21 g of polyphenols per 100 g of fresh weight (FW)) than unripe apple skin, being the most effective system tested and a mean degree of polymerization of 2.47. Commercial apple pomace was extracted with S1, resulting in a TPC of 0.5615 ± 0.007 g of polyphenols per 100 g of FW. Meanwhile, the RP-HPLC-MS analysis led to the tentative identification of several polyphenolic compounds.