Bui y Du

Preparation of colloidal silver nanoparticles in poly(N-vinylpyrrolidone) by γ-irradiation

Colloidal silver nanoparticles were prepared by γ-irradiating Ag+ in aqueous solution in the presence of 2% polyvinyl pyrrolidone (PVP) as stabilising agent and ethyl alcohol as free radical (OH•) scavenger. The saturated conversion dose of Ag+ into Ag was determined by UV–Vis spectroscopy and the silver nanoparticles size was characterised by transmission electron microscopy. The influence of Ag+ concentration (1–50 mM) on the saturated conversion dose and average diameter of silver nanoparticles was investigated. Results showed that the saturated conversion dose was from 8 to 48 kGy and the silver particles size was in the range of 6–21 nm for Ag+ concentration from 1 to 50 mM. The effect of PVP molecular weight on silver particles size was studied as well.

Effect of foliar application of oligochitosan with different molecular weight on growth promotion and fruit yield enhancement of chili plant

Abstract Oligochitosan (OC) is effective biostimulant on growth promotion and elicitation against disease infection for plants. However, the range of OC molecular weight that exhibits the most effective activity is not fully understood and requires further investigation. In this study, OCs with different weight average molecular weight (Mw) were prepared by gamma Co-60 irradiation degradation of chitosan in solution and the effect on growth promotion and enhancement of fruit yield of chili plant (Capsicum frutescens L.) by foliar application of OCs particularly with Mw of 7.8, 5.0, and 2.5 kDa was investigated. Chili plants, cultivated in a greenhouse were sprayed with OC concentration of 50 mg/L for three times. Results indicated that among treatments, OC with 2.5 kDa proved to be the best, which increased the shoot fresh weight by 71.5%, shoot dry weight by 184%, total chlorophyll content by 12%, and fruit fresh weight by 49.8% for the control. Thus, OC with low Mw (2.5 kDa) that can be suitably produced on large scale by gamma Co-60 ray irradiation degradation of chitosan solution is potentially promising to apply as a biostimulant to enhance chili fruit yield significantly.

Synthesis and Investigation of Antimicrobial Activity of Cu2O Nanoparticles/Zeolite

Cuprous oxide (Cu2O) nanoparticles in zeolite A were synthesized by two steps: (i) ion-exchange of copper ions into the zeolite and (ii) reduction of copper ions in cages of the zeolite by hydrazine hydrate in base medium. The Cu2O nanoparticles/zeolite product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The particle size of Cu2O nanoparticles was of 40 nm. The antibacterial activity of the as-synthesized Cu2O nanoparticles/zeolite against Escherichia coli was also investigated. Cu2O NPs/zeolite product can be favorably produced on large scale for water treatment and agricultural application as antimicrobial agent.

Effect of nanosilica/chitosan hybrid on leaf blast and blight diseases of rice in Vietnam

Nanosilica/chitosan (NSi/CTS) hybrid material was prepared using nanosilica (32.5 nm) from rice husk ash (RHA) and chitosan (CTS), and characterized by transmission electron microscopy (TEM), F ourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). The obtained NSi/CTS was used for protection of rice leaf from blast disease ( Piriculariaoryzae ) and blight disease ( Xanthomonasoryzae ). Results indicated that foliar spraying of NSi/CTS with 100 ppm NSiand150 ppm CTS were effective against blast and blight diseases on rice ( Oryza spp.). The leaf blast disease index (DI) (1.49 %) and the blight DI (1.45 %) were significantly decreased compared with control of 8.08 % and 9.29 %, respectively at 14 th day after the first treatment. Thus, NSi/CTS hybrid material is promising to use for controlling plant diseases, particularly for rice.

Preparation and characterization of nanosilica from rice husk ash by chemical treatment combined with calcination

This work presented the results of the study on synthesis and characterization of nanosilica from rice husk ash (RHA). Nanosilica was obtained by calcination of HCl treated RHA at 700 o C for 2 h. X-ray diffraction (XRD) pattern showed only one peak at 2q ~22 o confirming the amorphous structure of nanosilica. The chemical composition assessed by energy dispersive X-ray spectroscopy (EDX) showed that the obtained nanosilica was of high purity. TEM image measured by transmission electron microscopy (TEM) revealed that the obtained nanosilica was in spherical morphology with the average diameter of about 45.5±7.2 nm. The particle size distribution of nanosilica determined by dynamic laser scattering (DLS) was of Gaussian mode. The FTIR spectrum indicated the presence of silanol and siloxane groups in nanosilica. Thus, the synthesized nanosilica can be used for application in different fields. Keywords. Rice husk ash, nanosilica, amorphous.

Synthesis of silver nanoparticles deposited in porous ceramic by γ-irradiation

Silver nanoparticles (Ag nano) were deposited in porous ceramic (PC) that was functionalized with aminosilane (AS) agent (PC-AS-Ag nano) by gamma Co-60 irradiation of the PC-AS/Ag + mixture using polyvinylpyrrolidone (PVP) as stabilizer. Effect of dose on the formation of Ag nano was investigated. Characteristics of the nanocomposite material (PC-AS-Ag nano) were determined by ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Results indicated that Ag nano size was ~9 nm and the Ag nano content in PC-AS-Ag nano material was about of 341 ± 51 mg/kg at dose of 14-20 kGy. Thus, gamma Co-60 irradiation method has the advantage of creation of small Ag nanoparticles with fairly homogenous distribution in PC material.