Prospects of the Application of Garlic Extracts and Selenium and Silicon Compounds for Plant Protection against Herbivorous Pests: A Review

Protection of plants against herbivorous pests is an important aspect that guarantees agricultural efficiency, i.e., food provision to populations. Environmental, water and foodstuff pollution by toxic pesticides, along with climate changes, highlight the necessity to achieve intensive development of ecologically safe methods of herbivory control. This review discusses modern methods of plant protection against insect pests: the biofortification of plants with selenium, treatment of plants with bulk and nano-silicon, and utilization of garlic extracts. The peculiarities of such methods of defense are described in relation to growth stimulation as well as increasing the yield and nutritional value of products. Direct defense methods, i.e., mechanical, hormonal, through secondary metabolites and/or mineral element accumulation, and indirect defense via predator attraction are discussed. Examples of herbivorous pest control during plant growth and grain/seed storage are emphasized. A comparison of sodium selenate, silicon containing fertilizer (Siliplant) and garlic extract efficiency is analyzed on Raphanus sativus var. lobo infested with the cruciferous gall midge Contarinia nasturtii, indicating the quick annihilation of pests as a result of the foliar application of garlic extract or silicon-containing fertilizer, Siliplant.

Hydrometallurgical process development to recycle valuable metals from spent SCR deNOX catalyst

Spent catalyst, containing vanadium and tungsten oxide in a TiO2 glass fiber matrix, pose a risk of environmental contamination due to the high toxicity of its metal oxides if leached into the soil when disposed in landfills. Due to the increasing demand of metals and the continuous depletion of primary resources there is an growing necessity for recycling and reprocessing of spent catalysts and other secondary metal sources for environmental and economical reasons. Study of spent SCR catalyst soda roasting process with dissolved NaOH compared with the usual NaOH dry roasting and its influence in the subsequent water leaching. After optimization, the ideal parameters are roasting using a 0.4 ratio of NaOH/spent SCR catalyst in solution for 2 h at 973 K and de-ionized water leaching for 30 min, at 298 K with a pulp density of 30%. The research results show an important reduction of the roasting temperature and leaching time during the processing of spent SCR catalyst obtaining a 95.4% W and 80.2% V leaching efficiency liquor. Silicon compounds are one of the main impurities leached alongside the valuable metals and in this work, the silicon compounds leached are reduced significantly with the aim of avoiding the de-silication post-processing of the leach liquor. The main advantage of the proposed process is the increase of the leaching efficiency of vanadium and tungsten with a minimization of silicon impurities in a shorter time regardless of the leaching temperature.

Fractionation of solid component of welding aerosol

The design of portable filtration device with electrostatic filter and description of its work, which provides the trapping efficiency about 99.5% and fractionation of the polydisperse aerosol to four fractions via particles’ electrical mobility, are presented. The samples of aerosol particles’ fractions are obtained under usual welding regimes by welding wire Св08Г2С in CO2 and their specific surface area, element and phase compositions, phase ratio and crystallite sizes are determined. The correlation between fraction’s element composition and its specific surface area is demonstrated – the iron content is decreased, and manganese and silicon contents are increased when specific surface area is increased. The polyphase content (Fe3O4, FeO, FeMn2O4 и a-Fe are determined) and presence of the monocrystal nanosized magnetite particles, wustite and iron-manganese spinel in the fraction samples are confirmed by the X-ray analysis. The silicon compounds in particles are in amorphous state. The possibility of utilization of the nanostructured aerosol particles are proposed as a result of experimental data analysis.

On the hygienic rating of silicon compounds in drinking water (literature review)

Introduction. Silicon is a unique element in its physicochemical properties, almost ubiquitous in water supply sources but is not normalized in drinking water in the world practice of ensuring the harmlessness of water use of the population. In our country, the half-century history of the development of hygienic silicon standards in the water began with the justification of the MPC of silicon-containing reagents used in water treatment. However, over time, doubts have arisen about the suitability of manufactured silicon standards for controlling natural silicon in drinking water. Proponents of the harmlessness of natural soluble forms of silicon advocated the elimination of silicon standards in water. In contrast, researchers of the action of silicon in silicon biogeochemical provinces have constantly revealed its adverse effects on the health of the population living in these regions, confirming this with animal experiments. methods. Literature search methods on Scopus, CyberLeninka, PubMed databases: selective, analytical-synthetic, typological. the main part. The review provides information on soluble forms of silicon, their stability and bioavailability, examines the retrospective and current state of hygienic rationing of silicon in water, discusses the shortcomings of the currently existing MPC of silicon, sodium and potassium silicates in drinking water. A detailed review of studies carried out in the silicon biogeochemical provinces of Chuvashia is given, where the inhabitants of the ecological disaster zone, who consumed drinking water with a profound imbalance of macro-and microelements and a high silicon content relative to the optimum area, observed various metabolic disorders (mineral, lipid, carbohydrate, peroxide), changes in microbiocenosis of the large intestine and immune status, an increase in the incidence rate of the adult population with chronic non-infectious diseases by 2-3 times against the national average, the highest incidence rates in children of all age groups. Conclusions. The review draws attention to the need for expanded studies of the effect on the body of natural silicon in drinking water with the usual balance of trace elements to resolve issues about the standards for natural silicon at the federal and regional levels and to establish differentiated standards for silicon-containing reagents in drinking water.

A Wind Tunnel Experimental Study of Icing on NACA0012 Aircraft Airfoil with Silicon Compounds Modified Polyurethane Coatings

Ice formation on the aerodynamic surfaces of an aircraft is regarded as a major problem in the aerospace industry. Ice accumulation may damage parts, sensors and controllers and alter the aerodynamics of the airplane, leading to a range of undesired consequences, including flight delays, emergency landings, damaged parts and increased energy consumption. There are various approaches to reducing ice accretion, one of them being the application of icephobic coatings. In this work, commercially available polyurethane-based coatings were modified and deposited on NACA 0012 aircraft airfoils. A hybrid modification of polyurethane (PUR) topcoats was adopted by the addition of nanosilica and three-functional spherosilicates (a variety of silsesqioxane compound), which owe their unique properties to the presence of three different groups. The ice accretion on the manufactured nanocomposites was determined in an icing wind tunnel. The tests were performed under three different icing conditions: glaze ice, rime ice and mixed ice. Furthermore, the surface topography and wetting behavior (static contact angle and contact angle hysteresis) were investigated. It was found that the anti-icing properties of polyurethane nanocomposite coatings strongly depend on the icing conditions under which they are tested. Moreover, the addition of nanosilica and spherosilicates enabled the reduction of accreted ice by 65% in comparison to the neat topcoat.

INFLUENCE OF LIGNIN CONCENTRATION ON VISCOELASTIC PROPERTIES OF ITS MODIFIED FORM OB-TAINED BY SOL-GEL METHOD IN THE PRESENCE OF ALUMINUM-SILICON COMPOUNDS

The concept and flow model of a structured dispersed system obtained on the basis of sulfate lignin modified by Sol-gel method in the presence of aluminum-containing components in the form of nepheline concentrate are considered. The systems are mainly systems of non-Newtonian behavior, characterized by phenomena of destruction and formation of new structures in the shear flow, and the nature of the flow depends on the characteristics of interaction between system components, which are defined as their concentrations, and process conditions of the synthesis, at which the change of the adhesion forces between particles and at the moment cannot be generalized and described existing well-known equations of flow.As a result of the study, it was found that an increase in the concentration of sulfate lignin under various synthesis conditions, but with a constant amount of mineral component, leads to the formation of a new modified product, while there is a tendency to increase the parameters of kinematic viscosity and shear stress at the corresponding pH values of synthesis. Under conditions of excessive lignin concentrations of more than 400 mg/dm3, when self-organizing in the matrix of a new form, lignin dominance leads to a decrease in the strength characteristics of the polymer for all its forms obtained at different pH values. It is established that the kinematic viscosity and shear stress of water dispersions in this system depend on both the pH value of their synthesis and the concentration of the initial lignin, which determines the mechanisms of self-organization of the new modified structure.

Silicon carbide fibers and whiskers for ceramic matrix composites (review)

An increase the operating temperature range of structural elements and aircraft assemblies is one of the main goals in developing advanced and new models of aerospace equipment to improve their technical characteristics. The most heat-loaded aircraft structures, such as a combustion chamber, high-pressure turbine segments, nozzle flaps with a controlled thrust vector, must have a long service life under conditions of high temperatures, an oxidizing environment, fuel combustion products, and variable mechanical and thermal loads. At the same time, modern Ti and Ni-based superalloys have reached the limits of their operating temperatures. The leading world aircraft manufacturers — General Electric (USA), Rolls-Royce High Temperature Composite Inc. (USA), Snecma Propulsion Solide (France) — actively conduct fundamental research in developing ceramic materials with high (1300 – 1600°C) and ultrahigh (2000 – 2500°C) operating temperatures. However, ceramic materials have a number of shortcomings attributed to the high brittleness and low crack resistance of monolithic ceramics. Moreover, manufacturing of complex configuration and large-sized ceramic parts faces serious difficulties. Nowadays, ceramic composite materials with a high-temperature matrix (e.g., based on ZrC-SiC) and reinforcing filler, an inorganic fiber, (e.g., silicon carbide) appeared most promising for operating temperatures above 1200°C and exhibited enhanced energy efficiency. Ceramic fibers based on silicon compounds possess excellent mechanical properties: the tensile strength more than 2 GPa, modulus of elasticity more than 200 GPa, and thermal resistance at a temperature above 800°C, thus making them an essential reinforcing component in metal and ceramic composites. This review is devoted to silicon carbide core fibers obtained by chemical vapor deposition of silicon carbide onto a tungsten or carbon core, which makes it possible to obtain fibers a 100 – 150 μm in diameter to be used in composites with a metal matrix. The coreless SiC-fibers with a diameter of 10 – 20 μm obtained by molding a polymer precursor from a melt and used mainly in ceramic composites are also considered. A comparative analysis of the phase composition, physical and mechanical properties and thermal-oxidative resistance of fibers obtained by different methods is presented. Whiskers (filamentary crystals) are also considered as reinforcing fillers for composite materials along with their properties and methods of production. The prospects of using different fibers and whiskers as reinforcing fillers for composites are discussed.

Silicon Compounds in Sponges

A comparative study of the microscopic morphology and chemical characteristics of spicules of Hexactinellids (Hexactinellida) with different structural features of the skeletons, as well as the freshwater Baikal sponge belonging to the class of common sponges (Demospongia), was carried out. The trace element composition of sponge spicules was determined by X-ray fluorescence spectrometry. The spicules of siliceous sponges contain many elements, arranged in decreasing order of concentration: Si, Ca, Fe, Cl, K, Zn, and others. It was shown that the surface layer of sea sponges contains mainly carbon (C), oxygen (O), and to a lesser extent nitrogen (N), silicon (Si), and sodium (Na). The spicules of the studied siliceous sponges can be divided into two groups according to the phase composition, namely one containing crystalline calcium compounds and one without them. Analysis of infrared absorption spectra allows us to conclude that the sponges Euplectella aspergillum, E. suberia and Dactylocalyx sp. contain silica partially bound to the organic matrix, while the silica skeleton of the sponges of the other group (Schulzeviella gigas, Sericolophus sp., Asconema setubalense, Sarostegia oculata, Farrea sp. and Lubomirskia baicalensis sp.) practically does not differ from the precipitated SiO2. This comparative study of the chemical composition of the skeletons of marine Hexactinellids and common freshwater sponge allows us to conclude that there are no fundamental differences in the chemical composition of spicules, and all of them can be used as a starting material for creating new composite silicon–organic functional materials.

Novel Eco-friendly Roasting and Leaching Process Development to Recycle Valuable Metals from Spent SCR deNOX Catalyst

Spent catalyst, containing vanadium and tungsten oxide in a TiO2 glass fiber matrix, pose a risk of environmental contamination due to the high toxicity of its metal oxides if leached into the soil when disposed in landfills. Due to the increasing demand of metals and the continuous depletion of primary resources there is an growing necessity for recycling and reprocessing of spent catalysts and other secondary metal sources for environmental and economical reasons. Study of spent SCR catalyst soda roasting process with dissolved NaOH compared with the usual NaOH dry roasting and its influence in the subsequent water leaching. After optimization, the ideal parameters are roasting with 40% NaOH solution for 2h at 973K and DI water leaching for 30minutes, at 298K with a pulp density of 30%. The research results show an important reduction of the roasting temperature and leaching time during the processing of spent SCR catalyst with the objective to recover vanadium and tungsten. Silicon compounds are one of the main impurities leached alongside the valuable metals and in this work, the silicon compounds leached are reduced significantly avoiding the de-silication post-processing of the leach liquor. The main advantage of the proposed process is the increase of the leaching efficiency of vanadium and tungsten in a shorter time regardless of the leaching temperature.

DEVELOPMENT OF A BIODEGRADABLE MATERIAL FOR BONE REGENERATION BASED ON SILICON COMPOUNDS

In the course of this study we established that the laboratory sample in granulated form developed by us has a stimulating effect on the growth and proliferation of osteoblasts. Analysis of the data (CT, MRI) of the biological material obtained from the animals withdrawn from the experiment showed a statistically significant replacement of the artificial defect with bone tissue with signs of restoration of the cortical plate. The analysis of the CT results indicates that this method is sufficiently informative in assessing the regeneration of the trabecular structure of bone tissue. The study (MRI) of the bone material obtained from the animals participating in the experiment showed that when the osteoinductive material was integrated, the defect zone was replaced by 90%. In the projection of the defect, the newly formed tissue of a homogeneous structure was determined, corresponding in density to bone tissue with a high degree of mineralization. There was a complete restoration of bone tissue in the projection of the defect.