Applied Mechanics and Materials Vol. 835

Abstract: Nanostructure ZnO and Ag/ZnO were successfully synthesized from rice husk via an eco-friendly sol-gel method. Structural investigations by FT-IR and DR/UV-Vis analyses confirmed the successful inclusion of metal species into the silica framework. XRD and TEM studies evidenced the well-dispersion of silver and zinc onto the silica support. Modification of ZnO with Ag resulted in the maximum photocatalytic activity (90.5 %) of methylene blue, (40 mgL^-1) under compact fluorescent lamp irradiation. Minimal agglomeration, high dispersion and narrow band gap energy of Ag/ZnO was suggested to contribute to its excellent photocatalytic activity in comparison to ZnO.

Abstract: In this study, ZnO-Bi₂O₃-Mn₂O₃ varistors fabricated from the nanoparticle size of ZnO powder and doped with borosilicate frit were prepared via the conventional ceramic processing method. The influence of different borosilicate frit concentrations (0-3.0 mol%) on the sintering, microstructure enhancement, and nonlinear behavior of the ZnO-Bi₂O₃-Mn₂O₃ system was investigated. Results show that the borosilicate frit was liquefied to improve the density of the ceramic during sintering and found to have significant effects on the ZnO varistors, especially on enhancing grain growth even at a low doping concentration of only 0.5% mol. The strong solid-state reaction in the varistor made from 20 nm ZnO powder during sintering may be attributed to the high surface area of the 20 nm ZnO nanoparticles. X-ray diffraction analysis indicated that the addition of borosilicate frit to the ZnO-Bi₂O₃-Mn₂O₃ varistor system results in the formation of Zn₄O(BO₂)₆ during sintering if too much borosilicate frit was added (over 0.5% mol). Borosilicate frit doping also significantly influenced the electrical properties of the varistor with a marked drop in the breakdown voltage from 545 V to 188 V with increase of borosilicate frit doping concentration. The resistivity also experienced a dramatic drop from 535.7 kΩ.cm to 133.5 kΩ.cm with increase of borosilicate frit doping contents. Therefore, borosilicate frit doping can be used to control the structural properties and breakdown voltage of ZnO-Bi₂O₃-Mn₂O₃ varistor system fabricated from 20 nm ZnO powder.

Abstract: In this paper, the nano flexible polymer was synthesized and the plugging property of the polymer in the drilling fluid was studied. The characterization and properties of nano flexible polymer were invested by Particle Size Analyzer and Transmission Electron Microscopy. The nano flexible polymer was synthesized successfully and it was flexible nano material both in water and in drilling fluid. The filtration ability of the polymer was studied by drilling fluid filter press and the results indicated that the filtration property was equal to commonly used fluid loss agent in drilling fluid. The plugging ability was studied by specific surface and porosity physical adsorption instrument (BET). The surface area reduced after treated with the polymer, indicating the nano flexible polymer entered into nanopores of shale formation due to the adsorption in the surface of shale. It was further exhibited that nanopores of shale were plugged by the nano flexible polymer.

Abstract: The quantitative analysis of experimental results of research thermostimulated currents in crystals Bi₁₂SiO₂₀ (BSO) is lead carried out. Parameters of the capture centers in crystals BSO are determined.

Abstract: Thermochromic nano-pigments of ZnO and WO₃ co-doped VO₂ for mixing in paint were prepared by chemical method. The samples were successfully synthesized after annealing at 700°C for 1 h in nitrogen atmosphere. ZnO concentrations of 0.1, 0.3 and 0.5 at% were co-doped with WO₃ in VO₂. The 0.1 at% ZnO doping exhibited an amorphous phase, while 0.3 and 0.5 at% ZnO doping showed monoclinic phase having thermochromic transition temperatures of 59.43 and 52.60°C, respectively. The crystallite size of 0.5 at% ZnO doped monoclinic phase was 42 nm. The coating paints on glass substrates were prepared by mixing white colour paint with 0.1, 0.3 and 0.5 wt% of the 0.5 at% ZnO and WO₃ co-doped VO₂ nano-pigment. It was found that the paint with 0.5 wt% loading exhibited self-cleaning properties and 99.99% antibacterial against under UV irradiation for 40 min.

Abstract: (NH₄)₂Mo₄O₁₃ and h–MoO₃ nanocrystalline powders were synthesized by precipitation method at a varied pH range from 5.0 to 1.0. The crystal structure, morphology and optical property of samples were determined by X–ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–vis diffuse reflectance spectrophotometer (UV-vis DRS). At pH 2.0, 3.0 and 5.0, homogenous plate–like (NH₄)₂Mo₄O₁₃ was seen, whereas the heterogeneous hexagonal rod–shaped MoO₃ was found at very low pH of 1.0 and 1.5. Band gap energy of the synthesized (NH₄)₂Mo₄O₁₃ and h–MoO₃ were 3.38 and 3.18 eV, respectively. Photochromic properties of the products were illustrated by color difference before and after UV irradiation using CIE Lab color system. The synthesized h–MoO₃ provided a strong photochromic performance, while the (NH₄)₂Mo₄O₁₃ showed non–photochromic properties. Intercalation of H⁺ in h-MoO₃ were studied using electrochemical characterization by cyclic voltammetry (CV). The diffusion coefficient of the samples increases with decreasing pH of the solution.

Abstract: Skim natural rubber (NR)–clay nanocomposites were prepared by a coagulation method using the organoclays Cloisite 15A, Cloisite 20A and Cloisite 30B. This work investigated the use of bagasse fiber developed from locally sourced and renewable material as an alternative and/or secondary filler in skim NR–clay nanocomposites. Bagasse fiber loading in the nanocomposites was 0, 5, 10 and 20 phr; the effects of fiber content on cure characteristics and mechanical properties were then determined. The results suggest that the Mooney viscosity tended to increase with increasing fiber content, whereas the cure time at 90% and fatigue testing score decreased as fiber loading increased.

Abstract: The shielding against the UV radiation is one of the practical requirements for the textile industry. The in-situ synthesis process of ZnO nanorod arrays on silk fabric by the application of a hydrothermal method was described in this paper. Experimental parameters (concentration, temperature, time) were adjusted systematically to obtain the optimum. The results indicated that ZnO nanorod arrays grew well on silk fabric surface and enhanced UV-blocking property of the silk fabric.

Abstract: With the rapid development of nanotechnology, more and more nanomaterials are being fabricated and manipulated to perform the particular function, such as adhesive, biosensors, cosmetics, drug delivery system and artificial organ and tissue. On the other hand, nanotoxicity has become the topic of concern in nanotechnology because of the serious toxicity potentials of engineered nanomaterials on the living organisms. Many in vivo and in vitro studies clearly indicated that nanoparticles (NPs) are closely associated with toxicity by increasing intracellular reactive oxygen species (ROS) levels. And antioxidant supplementation is considered as useful against nanotoxicity related oxidative damages. At this point, in this investigation we assessed the protective abilities of selected 22 antioxidant or antioxidant featured agents against engineered nanoparticle exposure (ZnO NPs) model. We performed all experiments in cultured primary rat hepatocytes since the liver is a target site for NPs toxicity. Cell viability was detected by [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative alterations. Our results showed that each agent provided hepatoprotection in different degree. Propolis, boric acid and ascorbic acid were found to be the most effective ones while astaxanthine, L-glutamine and taurine were found to be less effective against nanoparticle induced oxidative injuries. The results presented here can be considered as the first information and rationale strategy on determining hepatoprotective potentials of common antioxidants against NP exposure for choosing the right antioxidant supplement for protecting liver.