Biosynthesis of Ag nanoparticles (AgNPs) by Cacumen Platycladi extract was investigated. The AgNPs were characterized by ultravioletÀvisible absorption spectroscopy (UVÀvis), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD). The results showed that increasing the initial AgNO 3 concentration at 30 or 60 °C increased the mean size and widened the size distribution of the AgNPs leading to red shift and broadening of the Surface Plasmon Resonance absorption. The conversion of silver ions was determined by atomic absorption spectroscopy (AAS) and to discuss the bioreductive mechanism, the reducing sugar, flavonoid, saccharide, protein contents in the extract, and the antioxidant activity were measured using 3,5-dinitrosalicylic acid colorimetric; Coomassie brilliant blue; phenol-sulfuric acid; rutin-based spectrophotometry method; and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay methods. The results showed that the reducing sugars and flavonoids were mainly responsible for the bioreduction of the silver ions and their reductive capability promoted at 90 °C, leading to the formation of AgNPs (18.4 ( 4.6 nm) with narrow size distribution. Finally, the antibacterial activity of the AgNPs against E. coli and S. aureus was assessed to determine their potential applications in silver-loaded antibacterial materials. This work provides useful technical parameters for industrialization of the biosynthetic technique and further antibacterial application of the AgNPs. Furthermore, the elucidation of bioreductive mechanism of silver ions by measuring the change of the biomolecular concentrations in plant extract exemplifies understanding the formation mechanism of such biogenic AgNPs.

40 nm flower-shaped Au-Pd bimetallic nanoparticles were prepared in a facile and eco-friendly way based on the simultaneous bioreduction of HAuCl 4 and Na 2 PdCl 4 with ascorbic acid and CacumenPlatycladi leaf extract at room temperature. Characterization techniques, such as transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, were employed to confirm that the as-synthesized nanoparticles were alloys. The obtained flower-shaped Au-Pd alloy nanoparticles exhibited an excellent surface enhanced Raman spectroscopic activity with rhodamine 6G and efficient catalytic ability for the oxidation of benzyl alcohol to benzaldehyde.

Oxygen-doped g-C 3 N 4 (CN) with carbon vacancies (O−CNC) was synthesized by microwave heating the mixture of melamine−cyanuric acid (MCA) supramolecular aggregates and oxalic acid for only 7 min. The as-synthesized O−CNC shows a mesoporous structure and exhibits a tunable band structure, optimized charge separation, and significantly enhanced twoelectron reduction for H 2 O 2 production. The photocatalytic H 2 O 2 production rate reaches 2008.4 μmol h −1 g −1 under simulated sunlight irradiation, which is more than 4 times higher than that of pristine bulk CN. The enhanced photocatalytic performance is attributed to the synergistic effects of the mesoporous structure with a large specific surface area, doped oxygen atoms, and carbon vacancies. These results have provided a facile and efficient way for realizing the practical application of CN in photocatalytic H 2 O 2 production. KEYWORDS: rapid microwave synthesis, mesoporous g-C 3 N 4 (CN), oxygen doping, carbon vacancies, photocatalytic H 2 O 2 production

Levulinic acid (LA) can be cost-effectively produced from a vast array of renewable carbohydrate-containing biomaterials. LA could facilitate the commercialization of the polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and PHBV-based products as carbon substrates. Therefore, this paper focused on the production of PHBV by Ralstonia eutropha with LA for hydroxyvalerate (HV) production, which plays an important role in enhancing the thermal properties of PHBV. Accordingly, the HV content of PHBV varied from 0–40.9% at different concentrations of LA. Stimulation of cell growth and PHBV accumulation were observed when 2–6 g L−1 LA was supplied to the culture. The optimal nitrogen sources were determined to be 0.5 g L−1 ammonium chloride and 2 g L−1 casein peptone. It was determined that the optimal pH for cell growth and PHBV accumulation was 7.0. When the cultivation was performed in large scale (2 L fermenter) with a low DO concentration of 30% and a pH of 7.0, a high maximum dry cell weight of 15.53 g L−1 with a PHBV concentration of 12.61 g L−1 (53.9% HV), up to 81.2% of the dry cell weight, was obtained. The melting point of PHBV found to be decreased as the fraction of HV present in the polymer increased, which resulted in an improvement in the ductility and flexibility of the polymer. The results of this study will improve the understanding of the PHBV accumulation and production by R. eutropha and will be valuable for the industrial production of biosynthesized polymers.

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