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Background Nano-particles of metals can be routinely synthesized. The cereal seeds treatment with the particles can improve early growth and crop production. Moreover, the treatment is robust and economical. Methods Metal (Fe0, Cu0, Co0), zinc oxide (ZnO) and chitosan-stabilized silver nano-particles were synthesized and applied to cereal seeds. The germination rate, early plant development and inhibition effects on pathogenic fungi were quantified. Results It was found that all nano-particles had a positive effect on the development of healthy cereal seedlings. In particular, the length of the above-ground part of the seedlings was increased by 8–22%. The highest inhibition effect was observed on Helminthosporium teres with the application of Co0 and chitosan-Ag. Pre-sowing treatment with metal nano-particles reduced the number of infected grains by two times for wheat and 3.6 times for barley. The application also increases the chlorophylls and carotenoids in both uninfected and infected seedlings. Conclusions The results demonstrated a robust application of nano-particles in improving cereal production. Graphical Abstract

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The extract from Celastrus hindsii (C. hindsii), a plant that naturally grows in the forests of several provinces of Vietnam, has been traditionally used as an alternative medicine for the treatment of inflammation because of its anticancer and antitumor properties. This study reported the green synthesis of stable gold nanoparticles (Au-NPs) derived from HAuCl4 using the extract of C. hindsii as reducing and capping agents. Their particle size could be controlled by adjusting the ratio of the extract to HAuCl4 solution used (1.25%, 2.5%, 3.75%, 5.0%, and 6.25%). The optimal ratio of the extract was 3.75% (Au-NPs-3.75%). The X-ray powder diffraction analysis demonstrated that the Au-NPs was successfully synthesized. Fourier-transform infrared spectroscopy result indicated the possible presence of phenolic acids and flavonoids (acting as reducing agents and potential natural antioxidants). Transmission electron microscopy images showed that the particle diameter of Au-NPs-3.75% varied between 13 and 53 nm (average: ∼30 nm) in its spherical shape. The biosynthesized Au-NPs-3.75% exhibited dose-dependent cytotoxicity against HeLa cells, and the inhibitory concentration (IC50) was 12.5 µg/mL at 48 h. Therefore, Au-NPs that were synthesized from environmentally friendly method without the presence of potentially toxic chemicals were highly possible in biomedical applications.

To avoid the instability and degradation of downhole injection fluids, such as polymers and surfactants, for use in high-temperature (HT) offshore reservoirs, nanofluids with particles modified in different ways have been proposed as a capable thermoresistant, highly active solutions which can be used in many offshore oil and gas exploitation works, especially in enhancing oil recovery. This study presented the process of synthesising two nanocomposite materials for nanofluid preparation. First, magnetite nanoparticles (MNPs(A and B)) were prepared by standard coprecipitation and hydrothermal methods. Then, polymer-coated magnetite nanoparticles (PCM(A) and PCM(B)) were synthesised by directly covering magnetite with oleic acid (OA) to get OA-MNPs, and then simultaneously enveloped with copolymers of acrylamide and the N-vinyl pyrrolidone via polymerisation reaction. The obtained PCMs characteristics were analysed by all required analytical tools. In addition, the thermostability of PCM-based nanofluids as downhole injection agents for HT offshore reservoir applications was investigated by bottle test annealing PCM(A)- and PCM(B)- based nanofluids at the White Tiger (WT) Miocene and Oligocene reservoir temperatures. Based on the obtained data, MNPs have an average particle size of 12 nm and 10 nm for MNPs A and B. A dominant phase of magnetite (Fe3O4) and 10.5% and 11% of the mass of PCM belong to their copolymer coating. The good thermostability of nanofluids annealed for 31 days (at 120 °C for PCM(A)- and 134 °C for PCM(B)-based nanofluids) showed a promised orientation for use as an EOR agent in HT offshore reservoirs recommendation.