A method for the synthesis of ZnO nanoparticles (ZnO NPs) gels was developed. ZnO NPs were obtained through a sol–gel method with zinc acetate usage as a precursor. Optimization of the method of synthesis of ZnO NPs gel has been carried out. It was observed that the most stable ZnO NPs gels are formed at room temperature, pH = 8 and molar concentration of zinc C(Zn2+) = 0.05–0.2 M. It was shown that the addition of polysaccharide significantly affects the rheological properties and microstructure of ZnO NPs gels. We found that the optimal polysaccharide for the synthesis of ZnO NPs gels is hydroxyethyl cellulose. It is shown that the microstructure of a gel of ZnO NPs stabilized with hydroxyethyl cellulose is represented by irregularly shaped particles that are assembled into aggregates, with sizes ranging from 150 to 1400 nm. A significant hysteresis region is observed in a gel of ZnO NPs stabilized with hydroxyethyl cellulose. The process of interaction of ZnO NPs with polysaccharides was investigated. It was shown that the interaction of ZnO NPs with polysaccharides occurs through a charged hydroxyl group. In the experiment, a sample of a gel of ZnO NPs modified with hydroxyethyl cellulose was tested. It was shown that the gel of ZnO NPs modified with hydroxyethyl cellulose has a pronounced regenerative effect on burn wounds, which is significantly higher than that of the control group and the group treated with a gel of ZnO microparticles (MPs) and hydroxyethyl cellulose. It is also shown that the rate of healing of burn wounds in animals treated with gel of ZnO nanoparticles with hydroxyethyl cellulose (group 3) is 16.23% higher than in animals treated with gel of ZnO microparticles with hydroxyethyl cellulose (group 2), and 24.33% higher than in the control group treated with hydroxyethyl cellulose. The average rate of healing of burn wounds for the entire experimental period in experimental animals of group 3 is 1.26 and 1.54 times higher than in animals of group 2 and control group, respectively. An experimental study of a gel of ZnO NPs modified with hydroxyethyl cellulose has shown the effectiveness of its use in modeling the healing of skin wounds through primary tension.
1 January 2018 in Ecotoxicology and Environmental Safety
The 36Cl/Cl ratios of annual precipitation samples, collected at 28 meteorological stations over the globe were measured with accelerator mass spectrometry. Local 36Cl fallout rates were obtained from the experimental data and compared with theoretical fluxes deduced from atmospheric cosmogenic production and an atmospheric transport model. Most of the measured fluxes were found to be larger than the predicted cosmogenic ones, up to about one order of magnitude. The deviations are largest in the northern hemisphere and for low latitudes. Recycling of 36Cl from nuclear weapon tests from the biosphere into the troposphere as CH3Cl is proposed as a possible source of the observed difference and can explain the measurements as simulation calculations showed.
This article presents the results of the synthesis of Se NPs stabilized by a quaternary ammonium compound—catamine AB. Se NPs were obtained by chemical reduction in an aqueous medium. In the first stage of this study, the method of synthesis of Se NPs was optimized by a multifactorial experiment. The radius of the obtained samples was studied by dynamic light scattering, and the electrokinetic potential was studied using acoustic and electroacoustic spectrometry. Subsequently, the samples were studied by transmission electron microscopy, and the analysis of the data showed that a bimodal distribution is observed in negatively charged particles, where one fraction is represented by spheres with a diameter of 45 nm, and the second by 1 to 10 nm. In turn, positive Se NPs have a diameter of about 70 nm. In the next stage, the influence of the active acidity of the medium on the stability of Se NPs was studied. An analysis of the obtained data showed that both sols of Se NPs exhibit aggregative stability in the pH range from 2 to 6, while an increase in pH to an alkaline medium is accompanied by a loss of particle stability. Next, we studied the effect of ionic strength on the aggregative stability of Se NPs sols. It was found that negatively charged ions have a significant effect on the particle size of the positive sol of Se NPs, while the particle size of the negative sol is affected by positively charged ions.
22 January 2022 in Journal of Food Composition and Analysis