Simulation study of random sequential adsorption of mixtures on a triangular lattice

Random sequential adsorption of binary mixtures of extended objects on a two-dimensional triangular lattice is studied numerically by means of Monte Carlo simulations. The depositing objects are formed by self-avoiding random walks on the lattice. We concentrate here on the influence of the symmetry properties of the shapes on the kinetics of the deposition processes in two-component mixtures. Approach to the jamming limit in the case of mixtures is found to be exponential, of the form: $\theta(t) \sim \theta_{jam}-\Delta\theta \exp (-t/\sigma),$ and the values of the parameter $\sigma$ are determined by the order of symmetry of the less symmetric object in the mixture. Depending on the local geometry of the objects making the mixture, jamming coverage of a mixture can be either greater than both single-component jamming coverages or it can be in between these values. Results of the simulations for various fractional concentrations of the objects in the mixture are also presented.Comment: 11 figures, 2 table

DNA metabarcoding and spatial modelling link diet diversification with distribution homogeneity in European bats

Inferences of the interactions between species’ ecological niches and spatial distribution have been historically based on simple metrics such as low-resolution dietary breadth and range size, which might have impeded the identification of meaningful links between niche features and spatial patterns. We analysed the relationship between dietary niche breadth and spatial distribution features of European bats, by combining continent-wide DNA metabarcoding of faecal samples with species distribution modelling. Our results show that while range size is not correlated with dietary features of bats, the homogeneity of the spatial distribution of species exhibits a strong correlation with dietary breadth. We also found that dietary breadth is correlated with bats’ hunting flexibility. However, these two patterns only stand when the phylogenetic relations between prey are accounted for when measuring dietary breadth. Our results suggest that the capacity to exploit different prey types enables species to thrive in more distinct environments and therefore exhibit more homogeneous distributions within their rangesinfo:eu-repo/semantics/publishedVersio

A dataset of acoustic measurements from soundscapes collected worldwide during the COVID-19 pandemic

Political responses to the COVID-19 pandemic led to changes in city soundscapes around the globe. From March to October 2020, a consortium of 261 contributors from 35 countries brought together by the Silent Cities project built a unique soundscape recordings collection to report on local acoustic changes in urban areas. We present this collection here, along with metadata including observational descriptions of the local areas from the contributors, open-source environmental data, open-source confinement levels and calculation of acoustic descriptors. We performed a technical validation of the dataset using statistical models run on a subset of manually annotated soundscapes. Results confirmed the large-scale usability of ecoacoustic indices and automatic sound event recognition in the Silent Cities soundscape collection. We expect this dataset to be useful for research in the multidisciplinary field of environmental sciences

Irreversible deposition of extended objects with diffusional relaxation on discrete substrates

Random sequential adsorption with diffusional relaxation of extended objects both on a one-dimensional and planar triangular lattice is studied numerically by means of Monte Carlo simulations. We focus our attention on the behavior of the coverage θ(t) as a function of time. Our results indicate that the lattice dimensionality plays an important role in the present model. For deposition of k-mers on 1D lattice with diffusional relaxation, we found that the growth of the coverage θ(t) above the jamming limit to the closest packing limit θCPL is described by the pattern θCPL - θ(t) ∝ Eβ[-(t/τ)β], where Eβ denotes the Mittag-Leffler function of order β ∈ (0,1). In the case of deposition of extended lattice shapes in 2D, we found that after the initial “jamming", a stretched exponential growth of the coverage θ(t) towards the closest packing limit θCPL occurs, i.e., θCPL - θ(t) ∝ exp[-(t/τ)β]. For both cases we observe that: (i) dependence of the relaxation time τ on the diffusion probability Pdif is consistent with a simple power-law, i.e., τ ∝ Pdif-δ; (ii) parameter β depends on the object size in 1D and on the particle shape in 2D

Effects of free-ranging cattle and landscape complexity on bat foraging: Implications for bat conservation and livestock management

Traditional agropastoralism increases biodiversity by maintaining habitats whose existence depends on human practices as well as by providing wildlife, including bats, with key spatial and trophic resources. Bats in farmland are crucial predators of crop pests, thus offering an economically important ecosystem service. It seems possible that bats may also provide services by feeding on insects associated with livestock. We tested whether bats forage over cattle in a traditionally managed pastoral area of central Italy, i.e. setting the bases for providing pest control services. We found that small bat species (mostly Pipistrellus spp.) foraged preferentially over livestock, and that their activity increased, but then reached a plateau or slightly decreased, for progressively larger herds. Landscape complexity also led to an increase in bat activity over livestock. Since insects attracted to cattle at night typically include flies such as mosquitoes (Culicidae) and biting midges (Ceratopogonidae), which are potentially harmful to cattle and may carry serious diseases, and that bats such as Pipistrellus spp. are important predators of such flies, we argue that bats may play a valuable pest-suppression role.Agriculture, Ecosystems & Environment (2017), 241: 54-6

Fractional kinetic model for granular compaction

We present an approach to granular compaction based on subordination of stochastic processes. In order to imitate, in a very simplified way, the compaction dynamics of granular material under tapping, we impose that particles switch stochastically between the two possible orientational states characterizing the average volumes of the grain in the presence of other grains. The main physical idea of our approach is that the interaction of grains with their environment is taken into account with the aid of the temporal subordination. Accordingly, we assume that the time intervals between the consecutive grain’s reorientations are governed by a certain waiting-time distribution ψ(t). It is demonstrated how the presence of the trapping events leads to the macroscopic observation of slow compaction dynamics, described by an exact fractional kinetic equation. We also perform numerical simulations to examine our analytical result. In addition, we reproduce the memory effects numerically by considering the response of the system to the abrupt change in the external excitation

INVESTIGATION OF POTENTIONAL USE OF RECYCLED POLY(ETHYLENE TEREPHTHALATE) IN POLYURETHANE SYNTHESIS

This paper presents an outline of developed methods for chemical recycling of postconsumer poly(ethylene terephthalate) (PET) waste bottles. Oligoesters (obtained by chemical recycled PET) with 2,2-bis (hydroxyl methyl) propionic acid, as hydrophobic monomer, and isophorone diisocyanate as cross-linker, in the presence of di-n-dibutyl tin(IV)dilaurate catalyst, were used for polyurethane dispersions. Molecular masses of obtained products were analyzed by gel permeation chromatography. Infra-red spectroscopy was used for molecular structures analysis. Thermal properties were evaluated by using differential scanning calorimetry and thermogravimetric analysis.This paper presents an outline of developed methods for chemical recycling of postconsumer poly(ethylene terephthalate) (PET) waste bottles. Oligoesters (obtained by chemical recycled PET) with 2,2-bis (hydroxyl methyl) propionic acid, as hydrophobic monomer, and isophorone diisocyanate as cross-linker, in the presence of di-n-dibutyl tin(IV)dilaurate catalyst, were used for polyurethane dispersions. Molecular masses of obtained products were analyzed by gel permeation chromatography. Infra-red spectroscopy was used for molecular structures analysis. Thermal properties were evaluated by using differential scanning calorimetry and thermogravimetric analysis

Is there a host sex bias in intestinal nematode parasitism of the yellow-necked mouse (Apodemus flavicollis) at Obedska bara pond, Serbia?

Fifty-one yellow-necked mice from the Obedska bara locality were analysed for the presence of intestinal nematode parasites in order to assert whether there was a host sex bias in infection. Previous research indicated that males would be the more infected sex, either due to the immunosuppressive effect of testosterone or their different allocation of resources towards immune defence. Quantitative infection parameters were compared between host sexes for all nematode species and nematodes in general. In addition, the influence of host sex, age, total body length, body mass and presence of other nematode species on parasite abundance was analysed. No statistically significant differences between males and females were noted for any of the studied quantitative parameters, leading to an absence of sex-biased parasitism in this study

The influence of montmorillonite modification on the properties of composite material based on poly(methacrylic acid)

In this work a new class of functional composites was prepared based on the organically modificated montmorillonite and methacrylic acid. In the first step, the native montmorillonite was mixed with poly(ethylenimine) monomer to promote the intercalation process. In the second step, the methacrylic acid and initiator (potassium persulfate) were added and polymerization was carried out at 80°C for 2 hours. Characterization of the obtained composite material was performed by Fourier transform infrared spectroscopy. The change in interlamellar spacing of montmorillonite after polymer composite preparation was determined by X-ray diffraction. In prepared composite samples the existence of two crystalline phases was estimated by X-ray measurements. In the first, the poly(methacrylic acid) chains are intercalated within the montmorillonite layers, and in the second, they are dispersed in the polymer matrix. The influence of montmorillonite on the thermal properties of the obtained composites was measured using the combined thermogravimetry and differential scanning calorimetry method. The porosity of the prepared samples was determined by isotherm adsorption and the desorption of nitrogen (Brunauer-Emmett-Teller method). It was assessed that a certain amount of polymer is deposited on the montmorillonite and thus covering of the micropores and partially covering of the mesopores was achieved