Slow-release agricultural pesticide formulations: state of the art

The need for a long-term sustaining of optimal concentrations of applied pesticides in the soil in agriculture resulted in the development of systems for controlled release of active substances. Such systems are based on the use of eco-friendly carrier materials that are harmless to plants, humans and environment. Inorganic substances (e.g., clays or alike substances), biodegradable polymers of natural or synthetic origin, blends of such polymers and their composites with inorganic fillers can be used as carriers. The deposited pesticides are released by diffusion or, in the case of systems based on biodegradable polymers, by degradation of the carrier. Inorganic carriers are usually impregnated with a pesticide. As for polymers, there is a wide range of methods for obtaining forms. Namely, these are the microsphere and nanoparticle formation, film casting, tablet pressing, form gelatinizing, and coprecipitation of a pesticide and a polymer from a solution. Co-extrusion of pesticides with polymers or their composites at temperatures below the degradation temperature of the components is another promising method for obtaining pesticide carriers

Degradable Polyhydroxyalkanoates as Herbicide Carriers

The biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) has been used to design experimental sustained-release formulations of the herbicide Zellek Super in the form of films and microgranules. The kinetics of polymer degradation and the dynamics of herbicide release show that the rate and extent of herbicide release from the polymer matrix into the soil depends on the geometry of the carrier and the proportion of the pesticide loaded into it (polymer/pesticide mass ratio). Experiments with the creeping bentgrass (Agrostis stolonifera L.) show that the formulations of the herbicide Zellek Super constructed as microgranules and films can be successfully used to suppress the growth of grasses. This study is the first to demonstrate that biodegradable polyhydroxyalkanoates can be used effectively to construct environmentally friendly sustained-release PHA-herbicide systems that can be placed into the soil together with seeds.Russia (Federation) (Agreement 11.G34.31.0013

Improvement of biocompatibility of high molecular weight poly-3-hydroxybutyrate by blending with its functionalized oligomers

Oligomers of poly-3-hydroxybutyrate (PHB) were prepared by aminolysis of high molecular weight PHB with ethylenediamine and 1,4-diaminobutane. Polymer-oligomer blends (10, 30, and 50% content of the oligomers) were prepared as films by solution casting. As the content of oligomers increased, a gradual increase in the hydrophilicity of the polymer surface was observed, resulting reflected in the water contact angle decrease from 84° to 72–76°. In addition, a moderate decrease in elongation at break, Young's modulus, and tensile strength for the blends were observed as more oligomer was added to the film. Finally, the viability of NIH-3T3 mouse fibroblasts was higher compared to intact PHB when growing in non-prepared polymer/oligomer mixtures. These findings confirm the benefits of the introduction of a hydrophilic functionalized oligomer into the PHB matrix in terms of improving the biocompatibility of the resulting polymer/oligomer blends

BLENDS OF POLY-3-HYDROXYBUTYRATE AND POLY-ε-CAPROLACTONE:MORPHOLOGY, PROPERTIES AND BIOCOMPATIBILITY

The use of biocompatible and biodegradable polymers is essential for modern biomedicine. One of the approaches to improving the mechanical properties of pure polymers is to obtain mixtures based on them.This work was carried within the state assignment of the Ministry of Science and Higher Education of the Russian Federation, project No. FEFE-2020-0015

MODIFICATION OF HIGH MOLECULAR WEIGHT POLY-3-HYDROXYBUTYRATE BY INTRODUCING ITS FUNCTIONALIZED OLIGOMERS

This work was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation, project No. FEFE -2020-0015

Взаимодействие сложных эфиров с хлористым тионилом, катализируемое галогенидами цинка

The ability of esters of primary and secondary alcohols butyl acetate and L‑menthyl acetate (2-isopropyl‑5-methylcyclohexyl acetate) to interact with thionyl chloride in the presence of zinc halides (chloride or bromide) was studied. 1-chlorobutane with a minor admixture of 2-chlorobutane (less than 3.6 %) was the main product of the reactions of butyl acetate. For L‑menthyl acetate, the main product was 2-chloro‑1-isopropyl‑4-methylcyclohexane with minor impurities mainly represented by 1-isopropyl‑4-methylcyclohexene and other six-membered unsaturated hydrocarbons. When ZnBr2 used as a catalyst, impurities of bromo- substituted hydrocarbons were found in the reaction products, which demonstrates the possibility of halogen atoms exchange between zinc halide and the resulting organic products of the reactionИсследована способность сложных эфиров первичного и вторичного спиртов – бутилацетата и L‑ментилацетата (2-изопропил‑5-метилциклогексилацетата), взаимодействовать с тионилхлоридом в присутствии галогенидов (хлорида или бромида) цинка. В качестве основного продукта реакции бутилацетата идентифицирован 1-хлорбутан, с минорной примесью (не превышающей 3.6 %) 2-хлорбутана. Для L‑ментилацетата основным продуктом являлся 2-хлор‑1-изопропил‑4-метилциклогексан; минорные примеси в основном представляли собой 4-метил‑1-изопропилциклогексен и другие непредельные углеводороды с шестичленным циклом. При использовании в качестве катализатора ZnBr2 в продуктах реакции обнаружены примеси бромзамещенных углеводородов, что показывает возможность обмена атомами галогенов между галогенидом цинка и образующимися органическими продуктами реакци

An Interactive Approach for Exploration of Flows Through Direction-Based Filtering

This paper is concerned with the representation and exploration of flows, defined as spatial interactions between geographic locations. Flows are challenging to display in a comprehensible manner due to the nature of the data, which are characterized by many crossings and overlaps leading to clutter. A number of different strategies have been suggested for addressing this problem, which commonly involve reducing the search space, aggregating the data or simplifying the representations often at the cost of information loss or distortion of spatial context. We propose an interactive approach for exploring large and highly connected networks of flows without distorting the geographical space and without losing the context overview in the process. The approach is based on a flow-specific interaction technique for filtering the data by direction, that enables an analyst to successively identify underlying spatial arrangement patterns. We illustrate our approach through exploring flows of tourists and locals in the Greater London area

Slow-Release Agricultural Pesticide Formulations: State of the Art

Received: 05.05.2022. Revised: 17.06.2022. Accepted: 17.06.2022. Available online: 27.06.2022.The application of soil pesticides often requires maintaining their concentrations at optimal levels during the growing season.This is complicated by the gradual degradation of the active components due to chemical and biological processes.The use of pesticides deposited in different carriers ensures long-term maintenance of optimal bioavailable concentrations in the soil.Clays, biodegradable polymers, their blends and composites are widely used as carriers of active components.The need for a long-term sustaining of optimal concentrations of applied pesticides in the soil in agriculture resulted in the development of systems for controlled release of active substances. Such systems are based on the use of eco-friendly carrier materials that are harmless to plants, humans and environment. Inorganic substances (e.g., clays or alike substances), biodegradable polymers of natural or synthetic origin, blends of such polymers and their composites with inorganic fillers can be used as carriers. The deposited pesticides are released by diffusion or, in the case of systems based on biodegradable polymers, by degradation of the carrier. Inorganic carriers are usually impregnated with a pesticide. As for polymers, there is a wide range of methods for obtaining forms. Namely, these are the microsphere and nanoparticle formation, film casting, tablet pressing, form gelatinizing, and coprecipitation of a pesticide and a polymer from a solution. Co-extrusion of pesticides with polymers or their composites at temperatures below the degradation temperature of the components is another promising method for obtaining pesticide carriers.This research was funded by the grant of the President of the Russian Federation for state support of young Russian scientists – candidates of science, provided by the Ministry of Science and Higher Education of the Russian Federation, “Ecological products with prolonged release of biologically active substances for potato nematode control” MK-4374.2021.5 No. 075-15-2021-059 dated 16.04.2021

Constructing slow-release formulations of ammonium nitrate fertilizer based on degradable poly(3-hydroxybutyrate)

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The present study describes construction and investigation of experimental formulations of ammonium nitrate embedded in a matrix of degradable natural polymer poly-3-hydroxybutyrate [P(3HB)] and P(3HB) blended with wood flour shaped as tablets, some of them coated with P(3HB). Kinetics of ammonium release into soil as dependent on the composition of the polymer matrix was investigated in laboratory experiments. The rates of fertilizer release from formulations coated with a biopolymer layer were considerably (two months or longer) slower than the rates of fertilizer release from uncoated formulations, while release from polymer and composite (polymer/wood flour) formulations occurred with comparable rates. The use of the experimental formulations in laboratory ecosystems with wheat (Triticum aestivum L.) was more effective than application of free ammonium nitrate. The advantage of the slow-release fertilizer formulations is that they are buried in soil together with the seeds, and the fertilizer remains effective over the first three months of plant growth. The use of such slow-release formulations will reduce the amounts of chemicals released into the environment, curbing their accumulation in food chains of ecosystems and mitigating their adverse effects on the biosphere