Obtaining a nanosized silica-humic preparation and its initial approbation

The recent decades have witnessed a significant development and implementation of nanotechnology, including in various branches of agriculture. There is an active search for ways to obtain preparations for plant growing with nanoparticles that can be more rapidly involved in the metabolic processes of plants. This article aims to obtain a nanosized silica-humic preparation and its approbation on potato plants. As a source of humic substances, a liquid humic preparation BoGum (developed by the All-Russian Research Institute of Reclaimed Lands) was used, as a source of silicon – sodium metasilicate. Ultrasonic dispersion method was used for achieving the nanoscale of the samples. A silicon source was introduced in an amount of 0.1% (of SiO2) into BoGum, followed by the application of ultrasonic action for 5, 10, 15 and 20 minutes. The analysis of the obtained samples using a 90 Plus/MAS particle size analyzer has shown that with increasing dispersion time, the effective particle diameter changed insignificantly. At the same time, a redistribution of particles was noted: when the samples were exposed for 20 minutes, the number of smaller particles increased. After 5 minutes of treatment, the range of particle distribution was 115±13–830±23 nm, after 20 minutes of exposure, the particle diameter fell into two regions: 81±8–120±10 and 280±4–470±18 nm. Ultrasonic action contributed to the retention of the stable state of aggregation of the obtained preparation, larger microbiological activity and larger content of humic acid in comparison with the silica-humic preparation, obtained without the application of an ultrasound. The new nanosized silica-humic preparation has been tested on potato plants. Treatment of tubers before planting, followed by foliar spraying of vegetative plants, has contributed to an increase in potato yield by 18.7%. Changes were noted in the content of mono- and polysilicic acids in the soil, as well as the accumulation of silicon in the tops of potatoes when using silicahumic preparations by 0.96% of absolute dry mass on average.

The use of nanosized additives in the modification of brick loam

The effect of nanosized additives on the strength properties of ceramics based on fusible brick loam of the Klyuchischenskoye deposit has been studied. In general, all nanosized additives selected for the study had a positive effect on the strength properties of ceramics. The greatest increase in strength, when using nanosized silica ash Laksil 30, was 70 %, in relation to the control sample. When using silica ash, an increase in the content of the amorphous phase in the shard after firing is noted against the background of a decrease in its porosity, which causes an increase in strength characteristics. The nature of the destruction of the samples also differed. The destruction of the control sample was accompanied by the formation and gradual opening of cracks. The destruction of the modified samples was more fragile in comparison with the control. Thus, the effectiveness of nanosized additives on the strength properties of ceramics is shown.

The Influence of Curing Systems on the Cure Characteristics and Physical Properties of Styrene–Butadiene Elastomer

The goal of this work is to study the influence of different curing systems on the cure characteristics and performance of styrene–butadiene elastomer (SBR) filled with carbon black or nanosized silica. A multifunctional additive for rubber compounds, namely Activ8, was applied as an additional activator and accelerator to increase the efficiency of sulfur vulcanization and to reduce the content of zinc oxide elastomers cured in the presence of 2-mercaptobenzothizole or 1,3-diphenylguanidine as a primary accelerator. The influence of the curing system composition on the crosslink density and physical properties of SBR vulcanizates, such as mechanical properties, thermal stability, and resistance to thermo-oxidative aging, is also reported. Activ8 effectively supports the vulcanization of SBR compounds, especially filled with nanosized silica. It reduces the optimal vulcanization time of SBR compounds and increases the crosslink density of the vulcanizates. Moreover, vulcanizates with Activ8 exhibit higher tensile strength and better damping properties than elastomer with zinc oxide. Activ8 allows the amount of ZnO to be reduced by 40% without detrimental effects on the crosslink density and mechanical performance compared to the vulcanizates conventionally crosslinked with ZnO. This is an important ecological goal since ZnO is classified as being toxic to aquatic species.

Moving toward Smart Cities: Evaluation of the Self-Cleaning Properties of Si-Based Consolidants Containing Nanocrystalline TiO2 Activated by Either UV-A or UV-B Radiation

This study evaluated the self-cleaning ability and durability of Si-based consolidants (an ethyl silicate consolidant and a consolidant based on nanosized silica) spiked with nanocrystalline TiO2 activated by either UV-A radiation (spectral region between 340 and 400 nm, and main peak at 365 nm) or UV-B radiation (spectral region between 270 and 420 nm, and main peak at 310 nm). Granite samples were coated with consolidant, to which nanocrystalline TiO2 was added at different concentrations (0.5, 1, and 3%, by wt.). Diesel soot was then applied to the coated surfaces, and the samples were exposed to UV-A or UV-B radiation for 1650 h. The surface color changes, relative to the color of untreated granite, were determined every 330 h by color spectrophotometry. Slight color changes indicated a recovery of the reference color due to the degradation of the soot. The final surfaces of both the untreated and treated surfaces were compared by stereomicroscopy and scanning electron microscopy. The main findings were that: (1) In general, the consolidant containing nanosized silica induced the most intense photocatalytic activity. In the more compact xerogel coating formed by the nanosized silica, more TiO2 nanoparticles were available to interact with the radiation. (2) For all consolidant mixtures, soot degradation remained constant or decreased over time, except with ethyl silicate with 0.5 wt % TiO2 (no self-cleaning capacity). (3) Soot degradation increased with the concentration of TiO2. (4) The UV-B radiation was the most effective in terms of soot degradation, except for the surface coated with the ethyl silicate and 3% wt. TiO2.

Increased Uptake of Silica Nanoparticles in Inflamed Macrophages but Not upon Co-Exposure to Micron-Sized Particles

Silica nanoparticles (NPs) are widely used in various industrial and biomedical applications. Little is known about the cellular uptake of co-exposed silica particles, as can be expected in our daily life. In addition, an inflamed microenvironment might affect a NP’s uptake and a cell’s physiological response. Herein, prestimulated mouse J774A.1 macrophages with bacterial lipopolysaccharide were post-exposed to micron- and nanosized silica particles, either alone or together, i.e., simultaneously or sequentially, for different time points. The results indicated a morphological change and increased expression of tumor necrosis factor alpha in lipopolysaccharide prestimulated cells, suggesting a M1-polarization phenotype. Confocal laser scanning microscopy revealed the intracellular accumulation and uptake of both particle types for all exposure conditions. A flow cytometry analysis showed an increased particle uptake in lipopolysaccharide prestimulated macrophages. However, no differences were observed in particle uptakes between single- and co-exposure conditions. We did not observe any colocalization between the two silica (SiO2) particles. However, there was a positive colocalization between lysosomes and nanosized silica but only a few colocalized events with micro-sized silica particles. This suggests differential intracellular localizations of silica particles in macrophages and a possible activation of distinct endocytic pathways. The results demonstrate that the cellular uptake of NPs is modulated in inflamed macrophages but not in the presence of micron-sized particles.

INFLUENCE OF NANOSIZED SILICA OXIDE SUSPENSION ON NITRIC OXIDE PRODUCTION IN RATS TESTES DURING CHRONIC NITRATE-FLUORIDE INTOXICATION

In the Poltava region of Ukraine there is a high possibility of combined excessive intake of nitrates and fluorides, since the waters of the Buchaksʹkii aquifer are rich in fluorine ions, moreover, the Poltava region is a region with a developed agriculture. The purpose of this work is to determine the effect of nanosized silicon oxide suspension on the changes in the activity of nitric oxide cycle components, components, and, namely the total activity of NO-synthases (NOS), the activity of constitutive forms of NOS (cNOS), inducible form of NOS (iNOS), nitrate reductase, nitrite reductase, nitrite reductase, nitrite reductase in the testes of rats under the conditions of chronic combined nitrate-fluorodide intoxication. Materials and methods. The study was conducted on 15 mature male Wistar rats weighing 200-253 g. The animals were randomly divided into 3 groups of 5 animals in each. The first group received daily saline solution through a gastric tube. The second group (chronic combined intoxication group) received sodium nitrate and fluoride in a dosage of 500 mg / kg of sodium nitrate and 10 mg / kg of sodium fluoride. The third group against the background of chronic combined intoxication modelling additionally received a suspension of nanosized silicon oxide is a dosage of 100 mg / kg of active substance. Results. Chronic combined intoxication increases total NOS activity by 65.9% compared to the control group. The increase in NO production by NOS is the result of a 4-fold increase in iNOS activity, since the activity of cNOS under these conditions does not change significantly. Nitrite reductase-dependent NO production increases by 66.7%, nitrate reductase activity increases by 77.8%. Nitrite content in the testes homogenate grows in 2.17 times. Hydrolytic cleavage of L-arginine by arginase increases in 2.88 times. The introduction of nanosized silicon oxide suspension under the conditions of chronic combined intoxication did not statistically significantly change the total NOS activity and cNOS activity compared to the group exposed to chronic intoxication. However, iNOS activity reduces in 3.69 times. Nitrate reductase activity decreases in 1.6 times, while nitrite reductase activity decreases in 45%. The activity of arginases lowered in 2.38 times. The nitrite content of the testes cut down by 23.6%. Conclusions. Chronic combined nitrate-fluoride intoxication leads to the development of hyperproduction of nitric oxide in the testes of rats by activating the inducible isoform of NO synthase and nitrite reductases. The use of nanosized silica suspension during chronic combined intoxication is an effective method to correct nitric oxide overproduction in the testes of rats.