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We model the spatiotemporal dynamics of a community consisting of competing weed and cultivated plant species and a population of specialized phytophagous insects used as the weed biocontrol agent. The model is formulated as a PDE system of taxis–diffusion–reaction type and computer-implemented for one-dimensional and two-dimensional cases of spatial habitat for the Neumann zero-flux boundary condition. In order to discretize the original continuous system, we applied the method of lines. The obtained system of ODEs is integrated using the Runge–Kutta method with a variable time step and control of the integration accuracy. The numerical simulations provide insights into the mechanism of formation of solitary population waves (SPWs) of the phytophage, revealing the factors that determine the efficacy of combined application of the phytophagous insect (classical biological method) and cultivated plant (phytocenotic method) to suppress weed foci. In particular, the presented results illustrate the stabilizing action of cultivated plants, which fix the SPW effect by occupying the free area behind the wave front so that the weed remains suppressed in the absence of a phytophage.

Combining explicit modelling of predator movements with the Kostitzin demo-genetic equations, we study conditions promoting natural selection of consumer motility. The model is a system of partial differential equations describing spatial movements of predators pursuing the diffusing prey. Local predator–prey interactions are described by the classical Rosenzweig–MacArthur model, which additionally accounts for the Allee effect affecting reproduction of predators. Spatial activity of predators is determined by the coefficients of diffusion and indirect prey-taxis. The latter characterizes the predator ability to move directionally up the gradient of taxis stimulus (odor, pheromone, exometabolite) continuously emitted by prey. Assuming that the consumer movement ability is governed by a single diallelic locus with recessive ‘mobile’ and dominant ‘settled’ alleles, the predator population in the model consists of three competing genotypes differing by diffusion and taxis coefficients; other parameters characterizing the genotypes are assumed to be equal. Numerical simulations with different spatial patterns imitating habitat deterioration demonstrate that the direction of selection among the consumer genotypes alternates, depending on the degree of habitat deterioration affecting the overall production of the prey population. Theoretical implications of the results are discussed in relation with problems of biological control, predator interference, and evolution of animal motility.

Purpose. The paper presents the second part of the review of the publications devoted to the problems of marine ecosystem modeling. In this part, major attention is paid to modern approaches to the management of marine biological resources which implement the ecosystem principles of modeling and monitoring the spatiotemporal dynamics of water objects. Methods and Results. The review consists of three sections. The first one deals with the models for forecasting dynamics of the exploited populations and for optimizing fishery. The second section considers the trophodynamic models used to study the structure, productivity, and functional role of marine biota interacting with other species and environment at various trophic levels. The trophodynamic models are often applied both for assessing the impact of fishery on marine ecosystems, and for analyzing the influence of the factors directly or indirectly related to climatic variability and anthropogenic activity (eutrophication, salinity, environmental changes). The third section of the review is devoted to a relatively recent direction in marine ecosystem modeling which is based on the geo-information systems. The onrush of the geo-information technologies permitting to connect the data both of the field observations and simulations with their geolocation had an impact on the achievements in the field of ecological modeling. Conclusions. In the coming years, the role of mathematical modeling in study and management of marine ecosystems will grow. The most important areas of research seem to be as follows: perfection of a model description of primary links in the marine ecosystem food webs (NPZD-models); the flows of matter and energy in the marine food chains; eutrophication and oxygen regime in the sea bays; distribution and transformations of pollutants, and their impact on ecosystems; functioning of marine reserves; the means of taking into account climatic factors in the ecosystem models; and application of satellite monitoring data for identifying and verifying the ecosystem individual components (chlorophyll, oil slicks, suspensions).

Purpose. Despite of a relatively short history of marine systems modeling, which started in late 1960s – early 1970s, this discipline is developing quite intensively. Publications on marine system modeling number in the thousands. The purpose of the article is to review the achievements accumulated in this field. The main attention is paid to the general principles in marine systems modeling, and to the spectrum of the applied modern approaches. The results of analysis of more than 200 sources, i.e. research papers, monographs, sections in books, internet-resources, are summarized in the paper of two parts published separately. Methods and Results. Over the past decades, our understanding of the patterns of marine ecosystems functioning has increased significantly, as well as the possibilities of ecological monitoring and information technologies. At the same time, the increasing number of global and regional environmental programs and projects in the field of rational use of marine resources, protection of marine ecosystems, and assessment of the climate change impacts has resulted in growth of demands for quantitative tools providing the ecosystem-based support of the initiatives in rational management of sea resources. This, in its turn, has required more complex multi-component models and led to significant increase in the number of such models. The first part of this review is focused on the end-to-end models which represent the complex integrative tools assisting in taking correct decisions for rational management of marine resource. Conclusions. Providing testing of scenarios “what, if”, the end-to-end models are the effective modeling instruments for assessing the consequences of climatic and anthropogenic impacts on all the trophic levels of marine ecosystems including bio-geo-chemical cycle, microbial loop, and various kinds of detritus. These models are not intended for taking tactical decisions (in such cases, local object-oriented sub-models should be used), but they are indispensable instruments in strategic planning and complex assessing of the management strategies.

We report the synthesis, structures, and magnetic and luminescence properties of a series of new monoand dinuclear Er3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4-tBu-2,6-(Ph2CH)2C6H2O]3Er(THF) (1), [(C6F5)3CO]3Er(Me3SiOH) (2), [(C6F5)3CO]3Er[(Me3Si)2NH] (3), [(C6F5)3CO]3Er(C6H5CH3) (4), [(C6F5)3CO]3Er(o-Me2NC6H4CH3) (5) and {[Ph(CF3)2CO]2Er(μ²-OC (CF3)2Ph)}2 (6). In compounds 1, 2, and 4, the Er3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er3+ is impacted by the presence of several relatively short Er...F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er3+ characteristic near infrared (NIR) emission associated with the 4I13/2 → 4I15/2 transition with a remarkably long lifetime going up to 73 µs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data. [ABSTRACT FROM AUTHOR]

The functional response (trophic function or individual ration) quantifies the average amount of prey consumed per unit of time by a single predator. Since the seminal Lotka-Volterra model, it is a key element of the predation theory. Holling has enhanced the theory by classifying prey-dependent functional responses into three types that long remained a generally accepted basis of modeling predator-prey interactions. However, contradictions between the observed dynamics of natural ecosystems and the properties of predator-prey models with Holling-type trophic functions, such as the paradox of enrichment, the paradox of biological control, and the paradoxical enrichment response mediated by trophic cascades, required further improvement of the theory. This led to the idea of the inclusion of predator interference into the trophic function. Various functional responses depending on both prey and predator densities have been suggested and compared in their performance to fit observed data. At the end of the 1980s, Arditi and Ginzburg stimulated a lively debate having a strong impact on predation theory. They proposed the concept of a spectrum of predator-dependent trophic functions, with two opposite edges being the prey-dependent and the ratio-dependent cases, and they suggested revising the theory by using the ratio-dependent edge of the spectrum as a null model of predator interference. Ratio-dependence offers the simplest way of accounting for mutual interference in predator-prey models, resolving the abovementioned contradictions between theory and natural observations. Depending on the practical needs and the availability of observations, the more detailed models can be built on this theoretical basis.

We discuss the interpretation and dimensions of the population dynamic parameters that are commonly used to quantify the strength of intraspecific and interspecific interactions. The concept of “interaction strength” is not unequivocal. Its theoretical formalization relies on the generalized Lotka–Volterra model. However, four different ways of parameterizing the model have been proposed in the literature, leading to four different definitions of the term “interaction strength.” In particular, the dimensions of these four definitions are not identical, some of these incorporating explicitly the dimension used to measure the population size. Using an individual-based simulation model as an illustration, we show that, in the latter case, the interaction strength depends implicitly on the habitat size. As a consequence, it is of crucial importance to quantify the population as a density rather than an absolute population abundance. We insist that the dimension of the interaction strength coefficient should not be overlooked and any quantitative estimation must be given with explicit units.

This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion’s with similar chemical moieties.

A simple mathematical model capable of reproducing formation of small-scale spatial structures in prey–predator system is presented. The migration activity of predators is assumed to be determined by the degree of their satiation. The hungrier individual predators migrate more frequently, randomly changing their spatial position. It has previously been demonstrated that such an individual response to local feeding conditions leads to prey–taxis and emergence of complex spatiotemporal dynamics at population level, including periodic, quasi-periodic and chaotic regimes. The proposed taxis–diffusion–reaction model is applied to describe the trophic interactions in system consisting of benthic diatom microalgae and harpacticoid copepods. The analytical condition for the oscillatory instability of the homogeneous stationary state of species coexistence is given. The model parameters are identified on the basis of field observation data and knowledge on the species ecology in order to explain micro-scale spatial patterns of these organisms, which still remain obscure, and to reproduce in numerical simulations characteristic size and the expected lifetime of density patches.

Under the conditions of the south-western part of the Central Black-soil region in the grain-and-plant crop rotation on the black-soil the typical maximum yield of winter wheat was 5.52 t/ha when using the organic-mineral fertilizer system as part of mineral fertilizers in the dose of N60P60K60 and manure in the dose of 40 t/ha according to the third level of plant protection (seed etching of herbicide fungicide insecticide growth substances) with maximum payback of 1 kg of mineral fertilizers with grain harvest increase – 15.5 kg. Yield increase at the 1st level of plant protection (seed etching) was 1.86 t/ha (68.1%), at the 2nd level of protection (seed etching of herbicide fungicide) – 2.55 t/ha (93.4%) and at the 3rd level of protection – 2.79 t/ha (102.2%). The highest increase from pesticides was 0.69 and 0.93 t/ha (15.0 and 20.3%), respectively. The use of such a fertilizer system is justified, in which the energy coefficient was 1.03 and 1.05. The design of an organic fertilizer system using manure does not meet the requirements of bioenergy efficiency at all levels of plant protection (Кee = 0.79-0.87).