Effects Of Dispersal Research Articles

Closing the gap: examining the impact of source habitat proximity on plant and soil microbial communities in post-mining spoil heap succession.

Revegetation of barren substrates is often determined by the composition and distance of the nearest plant community, serving as a source of colonizing propagules. Whether such dispersal effect can be observed during the development of soil microbial communities, is not clear. In this study, we aimed to elucidate which factors structure plant and soil bacterial and fungal communities during primary succession on a limestone quarry spoil heap, focusing on the effect of distance to the adjoining xerophilous grassland. We established a grid of 35 plots covering three successional stages - initial barren substrate, early successional community and late successional grassland ecosystem, the latter serving as the primary source of soil colonization. On these plots, we performed vegetation surveys of plant community composition and collected soil cores to analyze soil chemical properties and bacterial and fungal community composition. The composition of early successional plant community was significantly affected by the proximity of the source late successional community, however, the effect weakened when the distance exceeded 20 m. Early successional microbial communities were structured mainly by the local plant community composition and soil chemical properties, with minimal contribution of the source community proximity. These results show that on small spatial scales, species migration is an important determinant of plant community composition during primary succession while the establishment of soil microbial communities is not limited by dispersal and is primarily driven by local biotic and abiotic conditions.

Effect of dispersions on vapour permeation resistance of acrylic sealants

Currently, acrylic sealants are widespread due to their environmentally friendly materials, ease of use, and low cost. Their compositions are constantly being improved. It allows ones to improve their quality and reduce the cost by selecting new substances for their manufacture. We obtained acrylic sealants with changing polymer base. The authors used acrylic and styrene acrylic dispersions obtained by emulsion polymerisation. The basis for sealants production is the mechanical mixing of the components and their further dispersion in the Dispermat VLOK dissolver. The main parameter to be determined is the vapour permeability resistance of the material layer. According to research results, the nature of the polymer base, degree of its bonding, type and amount of the filler used affected on vapour permeability of the sealing material. Moreover, increasing in film former temperature, viscosity, and pH causes increasing in tensile strength. By comparing the sealant samples on the basis of dry residue, we found increasing of the Shore hardness in samples with lower % index.

Effect of anisotropy and length dispersity on electrical and optical properties ofnanowire network based transparent electrodes: a computational study.

We have studied the impact of nanowire alignment and measurement direction at the percolation
threshold on the effective resistance (R) of two-dimensional (2D) films. This helps us to analyze the
effect of anisotropy on the conductivity and transmittance of the nanowire-based network characterized by the disorder parameter (s). These optoelectronic properties are determined for systems
with monodisperse as well as bimodal distribution of length. The 2D systems that are simulated using our computational approach are assumed to be transparent and conductive in which percolative transport is the primary conduction mechanism.
We obtain our results numerically using a computational and geometrical approach, i.e., a Discrete
(grid) method, advantageous in algorithm speed. For a particular disorder parameter s,
the conductivity and transmittance increase as the length fraction increases for the bimodal
distribution of the length of nanowires in networks. We have observed the maximum conductivity
when the nanowires are highly aligned along the measurement direction of percolation, in contrast
to the isotropic arrangement of nanowires. Significantly, alignment introduced in nanowires leads
to a higher percolation threshold which leads to a decrease in the transmittance of the network. We
show that the resistivity of the monodisperse network in the direction parallel (perpendicular) to the
alignment decreases (increases) with the disorder parameter and scales as s (s2). This scaling holds
true for the bimodal distribution of nanowires as well. For a particular length fraction, the electrical
anisotropy increases with s. The anisotropy is maximum for nearly aligned nanowires in a bimodal
network with the highest proportion of the longest wire considered. For the maximally aligned wires
and highest length fraction, we obtained an approximately 50% enhancement in the figure of merit,
denoted by ϕ. Hence, incorporating longer length wires and increasing the alignment in nanowire
networks increases the conductivity, anisotropy, and figure of merit.

New insights into the combined effect of dispersal and local dynamics in a two-patch population model

Understanding the effect of dispersal on fragmented populations has drawn the attention of ecologists and managers in recent years, and great efforts have been made to understand the impact of dispersal on the total population size. All previous numerical and theoretical findings determined that the possible response scenarios of the overall population size to increasing dispersal are monotonic or hump-shaped, which has become a common assumption in ecology. Against this, we show in this paper that many other response scenarios are possible by using a simple two-patch discrete-time model. This fact evidences the interplay of local dynamics and dispersal and has significant consequences from a management perspective that will be discussed.

Stability and bifurcation in a two-patch commensal symbiosis model with nonlinear dispersal and additive Allee effect

In this paper, a two-patch model with additive Allee effect, nonlinear dispersal and commensalism is proposed and studied. The stability of equilibria and the existence of saddle-node bifurcation, transcritical bifurcation are discussed. Through qualitative analysis of the model, we know that the persistence and the extinction of population are influenced by the Allee effect, dispersal and commensalism. Combining with numerical simulation, the study shows that the total population density will increase when the Allee effect constant [Formula: see text] increases or [Formula: see text] decreases. In addition to suppress the Allee effect, nonlinear dispersal and commensalism are crucial to the survival of the species in the two patches.

Changes in the Aggregation Behaviour of Zinc Oxide Nanoparticles Influenced by Perfluorooctanoic Acid, Salts, and Humic Acid in Simulated Waters.

The increasing utilization of zinc oxide nanoparticles (ZnO-NPs) in many consumer products is of concern due to their eventual release into the natural environment and induction of potentially adverse impacts. The behaviour and environmental impacts of ZnO-NPs could be altered through their interactions with environmentally coexisting substances. This study investigated the changes in the behaviour of ZnO-NPs in the presence of coexisting organic pollutants (such as perfluorooctanoic acid [PFOA]), natural organic substances (i.e., humic acid [HA]), and electrolytes (i.e., NaCl and CaCl2) in simulated waters. The size, shape, purity, crystallinity, and surface charge of the ZnO-NPs in simulated water after different interaction intervals (such as 1 day, 1 week, 2 weeks, and 3 weeks) at a controlled pH of 7 were examined using various characterization techniques. The results indicated alterations in the size (such as 162.4 nm, 1 day interaction to >10 µm, 3 weeks interaction) and zeta potential (such as -47.2 mV, 1 day interaction to -0.2 mV, 3 weeks interaction) of the ZnO-NPs alone and when PFOA, electrolytes, and HA were present in the suspension. Different influences on the size and surface charge of the nanoparticles were observed for fixed concentrations (5 mM) of the different electrolytes. The presence of HA-dispersed ZnO-NPs affected the zeta potential. Such dispersal effects were also observed in the presence of both PFOA and salts due to their large aliphatic carbon content and complex structure. Cation bridging effects, hydrophobic interactions, hydrogen bonding, electrostatic interactions, and van der Waals forces could be potential interaction forces responsible for the adsorption of PFOA. The presence of organic pollutants (PFOA) and natural organic substances (HA) can transform the surface characteristics and fate of ZnO-NPs in natural and sea waters.

Tetramerized Small‐Molecule Acceptor for Organic Solar Cells with Enhanced Efficiency, Stability, and Mechanical Robustness: Impact of Chain Length and Dispersity Effects

Tetramerized Small‐Molecule Acceptor for Organic Solar Cells with Enhanced Efficiency, Stability, and Mechanical Robustness: Impact of Chain Length and Dispersity Effects

Development of Albendazole Nanodispersion for the Effective Treatment of Helminthiasis

Albendazole is a drug used to treat parasitic worm infections. ALB results in the tegument and intestinal cells of the worm undergoing degenerative changes, which ultimately lead the parasite to become immobile and die. The purpose of the study was to improve the solubility and effectiveness of an ALB-loaded solid nano dispersion for the effective treatment of helminthiasis.ALBFs were generated by a solvent evaporation procedure involving PVPK30 and carbopol, which may improve the stability of controlled drug release rates. The newly found ALBFs are more soluble than pure albendazole and have a better bioavailability. ALBFs allow for the optimization of therapeutic efficacy while lowering potential side effects and modulating enzymatic resistance, degradation, and drug release rate. Thus, the created ALBFs demonstrated successful helminthiasis treatment with lower dose frequency.

The Irradiation Effects in Ferritic, Ferritic-Martensitic and Austenitic Oxide Dispersion Strengthened Alloys: A Review.

High-performance structural materials (HPSMs) are needed for the successful and safe design of fission and fusion reactors. Their operation is associated with unprecedented fluxes of high-energy neutrons and thermomechanical loadings. In fission reactors, HPSMs are used, e.g., for fuel claddings, core internal structural components and reactor pressure vessels. Even stronger requirements are expected for fourth-generation supercritical water fission reactors, with a particular focus on the HPSM's corrosion resistance. The first wall and blanket structural materials in fusion reactors are subjected not only to high energy neutron irradiation, but also to strong mechanical, heat and electromagnetic loadings. This paper presents a historical and state-of-the-art summary focused on the properties and application potential of irradiation-resistant alloys predominantly strengthened by an oxide dispersion. These alloys are categorized according to their matrix as ferritic, ferritic-martensitic and austenitic. Low void swelling, high-temperature He embrittlement, thermal and irradiation hardening and creep are typical phenomena most usually studied in ferritic and ferritic martensitic oxide dispersion strengthened (ODS) alloys. In contrast, austenitic ODS alloys exhibit an increased corrosion and oxidation resistance and a higher creep resistance at elevated temperatures. This is why the advantages and drawbacks of each matrix-type ODS are discussed in this paper.

Source-Sink Dynamics in a Two-Patch SI Epidemic Model with Life Stages and No Recovery from Infection.

This study presents a comprehensive analysis of a two-patch, two-life stage SI model without recovery from infection, focusing on the dynamics of disease spread and host population viability in natural populations. The model, inspired by real-world ecological crises like the decline of amphibian populations due to chytridiomycosis and sea star populations due to Sea Star Wasting Disease, aims to understand the conditions under which a sink host population can present ecological rescue from a healthier, source population. Mathematical and numerical analyses reveal the critical roles of the basic reproductive numbers of the source and sink populations, the maturation rate, and the dispersal rate of juveniles in determining population outcomes. The study identifies basic reproduction numbers for each of the patches, and conditions for the basic reproduction numbers to produce a receiving patch under which its population. These findings provide insights into managing natural populations affected by disease, with implications for conservation strategies, such as the importance of maintaining reproductively viable refuge populations and considering the effects of dispersal and maturation rates on population recovery. The research underscores the complexity of host-pathogen dynamics in spatially structured environments and highlights the need for multi-faceted approaches to biodiversity conservation in the face of emerging diseases.

Assessing the extinction risk of the spontaneous flora in urban tree bases.

As the spatial arrangement of trees planted along streets in cities makes their bases potential ecological corridors for the flora, urban tree bases may be a key contributor to the overall connectivity of the urban ecosystem. However, these tree bases are also a highly fragmented environment in which extinctions are frequent. The goal of this study was to assess the plant species' ability to survive and spread through urban tree bases. To do so, we developed a Bayesian framework to assess the extinction risk of a plant metapopulation using presence/absence data, assuming that the occupancy dynamics was described by a Hidden Markov Model. The novelty of our approach is to take into account the combined effect of low-distance dispersal and the potential presence of a seed bank on the extinction risk. We introduced a metric of the extinction risk and examined its performance over a wide range of metapopulation parameters. We applied our framework to yearly floristic inventories carried out in 1324 tree bases in Paris, France. While local extinction risks were generally high, extinction risks at the street scale varied greatly from one species to another. We identified 10 plant species that could survive and spread through urban tree bases, and three plant traits correlated with the extinction risk at the metapopulation scale: the maximal height, and the beginning and end of the flowering period. Our results suggest that some plant species can use urban tree bases as ecological corridors despite high local extinction risks by forming a seed bank. We also identified other plant traits correlated with the ability to survive in tree bases, related to the action of gardeners. Moreover, our findings demonstrate that our Bayesian estimation framework based on percolation theory has the potential to be extended to more general metapopulations.

Dispersal-diversity feedbacks and their consequences for macroecological patterns.

Dispersal is a key process in ecology and evolution. While the effects of dispersal on diversity are broadly acknowledged, our understanding of the influence of diversity on dispersal remains limited. This arises from the dynamic, context-dependent, nonlinear and ubiquitous nature of dispersal. Diversity outcomes, such as competition, mutualism, parasitism and trophic interactions can feed back on dispersal, thereby influencing biodiversity patterns at several spatio-temporal scales. Here, we shed light on the dispersal-diversity causal links by discussing how dispersal-diversity ecological and evolutionary feedbacks can impact macroecological patterns. We highlight the importance of dispersal-diversity feedbacks for advancing our understanding of macro-eco-evolutionary patterns and their challenges, such as establishing a unified framework for dispersal terminology and methodologies across various disciplines and scales. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.

Niche partitioning and plastisphere core microbiomes in the two most plastic polluted zones of the world ocean.

Plastics are offering a new niche for microorganisms colonizing their surface, the so-called "plastisphere," in which diversity and community structure remain to be characterized and compared across ocean pelagic regions. Here, we compared the bacterial diversity of microorganisms living on plastic marine debris (PMD) and the surrounding free-living (FL) and organic particle-attached (PA) lifestyles sampled during the Tara expeditions in two of the most plastic polluted zones in the world ocean, i.e., the North Pacific gyre and the Mediterranean Sea. The 16S rRNA gene sequencing analysis confirmed that PMD are a new anthropogenic ocean habitat for marine microbes at the ocean-basin-scale, with clear niche partitioning compared to FL and PA lifestyles. At an ocean-basin-scale, the composition of the plastisphere communities was mainly driven by environmental selection, rather than polymer types or dispersal effect. A plastisphere "core microbiome" could be identified, mainly dominated by Rhodobacteraceae and Cyanobacteria. Predicted functions indicated the dominance of carbon, nitrogen and sulfur metabolisms on PMD that open new questions on the role of the plastisphere in a large number of important ecological processes in the marine ecosystem.

Dispersal limitation and environmental filtering effects: The taxonomic and functional beta diversity of ground beetles along the altitudinal gradient in Chinese warm-temperature forests.

Beta diversity patterns along environmental gradients and underlying mechanisms constitute key research inquiries in biogeography. However, ecological processes often also influence the functional traits of biological communities, making the assessment of functional β-diversity crucial. Ground beetles (Coleoptera: Carabidae) are one of the most species-rich groups in the insect community, displaying strong habitat specificity and morphological differences. In this study, we explored the patterns of taxonomic and functional beta diversity in ground beetle communities along the altitudinal gradient of warm-temperature forests. By partitioning beta diversity into turnover and nestedness components, we evaluated their relationship with spatial distance. Our findings indicate a decline in species and functional trait similarity with increasing elevation and geographic distance. Further analysis attributed both types of beta diversity in carabids to a combination of dispersal limitation and environmental filtering, with elevation and geographic distance emerging as significant factors. Interestingly, forest-type variations were found to have no impact on the beta diversity of these communities. Our study reveals the impact of environmental filtering and dispersal limitation on both taxonomic and functional beta-diversity, shedding light on carabid community assembly in localized warm-temperature forest areas in eastern China.

Ex vivo permeability study and in vitro solubility characterization of oral Canagliflozin self-nanomicellizing solid dispersion using Soluplus® as a nanocarrier

Abstract Background and objective: Self-nanomicellizing solid dispersion SNMSD is a new formulation that combines solid dispersion and nanomicelle strategies; the strategy involves utilizing a suitable carrier that self-assembles into nanomicelles when interacting with gastrointestinal fluids. Canagliflozin, a sodium-glucose cotransporter-2 inhibitor for treating type 2 diabetes, has been linked to poor absorption due to its insolubility in aqueous media. The study aimed to create self-nanomicellizing solid dispersion systems for canagliflozin to overcome its pharmaceutical limitations and improve oral bioavailability. Materials and Methods: Soluplus® was chosen as a nanocarrier to improve canagliflozin solubility after screening several polymers using a phase solubility study. The solvent evaporation method was selected for preparing the solid dispersion. The optimal formula was characterized through ex vivo permeability and in vitro studies. Results: The CFZ-SNMSD formula, with a particle size PS of 60.77±1.00 nm and polydispersity index PDI of 0.06±0.02, has a stable distribution upon dilution to 20-fold with water. The apparent solubility of canagliflozin in the optimized CFZ-SNMSD formula was enhanced by 904.40±4 folds due to amorphization and nanomicellization, as demonstrated by transmission electron microscopy. CFZ-SNMSD formula showed a significant enhancement in dissolution rate compared to the physical mixture and pure drugs. The dissolution efficiency parameter confirms these findings (DE30, CFZ-SNMSD = 77.20% compared to DE30, pure drug = 18.28%). Studies show that canagliflozin’s permeability increases exponentially over time due to Soluplus® dispersibility, solubilization, and glycoprotein inhibitory effect, enhancing bioavailability and overcoming GIT membrane barriers. Conclusions: The study indicates that canagliflozin self-nanomicellizing solid dispersion systems are promising methods for improving the oral bioavailability of canagliflozin medication.

Dispersal‐related plant traits are associated with range size in the Atlantic Forest

AbstractAimThe efficiency of animal‐mediated seed dispersal is threatened by the decline of animal populations, especially in tropical forests. We hypothesise that large‐seeded plants with animal‐mediated dispersal tend to have limited geographic ranges and face an increased risk of extinction due to the potential decline in seed dispersal by large‐bodied fruit‐eating and seed‐dispersing animals (frugivores).LocationAtlantic Forest, Brazil, South America.TaxonAngiosperms.MethodsFirst, we collected dispersal‐related traits (dispersal syndrome, fruit size, and seed size), growth form (tree, climber, and other) and preferred vegetation type (open and closed) data for 1052 Atlantic Forest plant species. Next, we integrated these with occurrence records, extinction risk assessments, and phylogenetic trees. Finally, we performed phylogenetic generalised least squares regressions to test the direct and interactive effects of dispersal‐related traits and vegetation type on geographical range size.ResultsLarge‐seeded species had smaller range sizes than small‐seeded species, but only for species with animal‐mediated dispersal, not for those dispersed by abiotic mechanisms. However, plants with abiotic dispersal had overall smaller range sizes than plants with animal‐mediated dispersal. Furthermore, we found that species restricted to forests had smaller ranges than those occurring in open or mixed vegetation. Finally, at least 29% of the Atlantic Forest flora is threatened by extinction, but this was not related to plant dispersal syndromes.Main ConclusionsLarge‐seeded plants with animal‐mediated dispersal may be suffering from dispersal limitation, potentially due to past and ongoing defaunation of large‐bodied frugivores, leading to small range sizes. Other factors, such as deforestation and fragmentation, will probably modulate the effects of dispersal on range size, and ultimately extinction. Our study sheds light on the relationship between plant traits, mutualistic interactions, and distribution that are key to the functioning of tropical forests.

Effect of nano-carbon black content and dispersibility on the properties of cement paste

In this study, we analyzed the microstructure, pore structure, and changes in electromagnetic parameters of cement paste with nano-carbon black (CB) added. The following conclusions were drawn: The addition of CB significantly influenced the pore structure of the cement paste, increasing the content of pores less than 100 nm and improving the overall pore structure. The use of the dispersant further enhanced the dispersion of CB and increased its filling effect. Additionally, adding CB had a significant impact on the compressive strength of the cement paste; the presence of certain CB aggregates reduced the compressive strength. However, when the CB content was 0.5wt%, the use of the dispersant decreased the size of CB aggregates and effectively increased the compressive strength. SEM images displayed the dispersion state of CB aggregates within the cement paste, demonstrating that the size and quantity of aggregates could be reduced through the use of the dispersant. The change in the CB dispersion state also slightly affected the electromagnetic parameters and wave absorption properties of the cement paste. The research results presented in this paper offer valuable insights for the design and application of CB cement paste.

One way or another: Combined effect of dispersal and asymmetry on total realized asymptotic population abundance

Understanding the consequences on population dynamics of the variability in dispersal over a fragmented habitat remains a major focus of ecological and environmental inquiry. Dispersal is often asymmetric: wind, marine currents, rivers, or human activities produce a preferential direction of dispersal between connected patches. Here, we study how this asymmetry affects population dynamics by considering a discrete-time two-patch model with asymmetric dispersal. We conduct a rigorous analysis of the model and describe all the possible response scenarios of the total realized asymptotic population abundance to a change in the dispersal rate for a fixed symmetry level. In addition, we discuss which of these scenarios can be achieved just by restricting mobility in one specific direction. Moreover, we also report that changing the order of events does not alter the population dynamics in our model, contrary to other situations discussed in the literature.

Influence of alternating electric field on electrorheological effect of aqueous dispersions of stevensite

Upon deionization of the aqueous dispersion of stevensite, a type of smectite clay minerals, a low-viscosity colorless transparent dispersion is obtained. The phenomenon known as the electrorheological (ER) effect has been previously reported when a weak electric field of several V/mm is applied to the stevensite aqueous dispersion. In this study, the influence of the waveform and frequency of the electric field was investigated while keeping the electric field intensity constant. It was observed that as the acceleration of the applied electric field intensity increased, the stress response to the electric field improved. Increasing the frequency of the electric field led to a reduction in the induced stress; however, it improved the response rate of stress. It has been indicated that even at higher electric field frequencies, the potential for observing the ER effect exists with higher electric field intensities. Maintaining a low electrolyte concentration may facilitate the development of novel ER fluids capable of instantaneously responding to the application or removal of electric fields.

Stochastic microbial dispersal drives local extinction and global diversity.

Airborne dispersal of microorganisms is a ubiquitous migration mechanism, allowing otherwise independent microbial habitats to interact via biomass exchange. Here, we study the ecological implications of such advective transport using a simple spatial model for bacteria-phage interactions: the population dynamics at each habitat are described by classical Lotka-Volterra equations; however, species populations are taken as integer, that is, a discrete, positive extinction threshold exists. Spatially, species can spread from habitat to habitat by stochastic airborne dispersal. In any given habitat, the spatial biomass exchange causes incessant population density oscillations, which, as a consequence, occasionally drive species to extinction. The balance between local extinction events and dispersal-induced migration allows species to persist globally, even though diversity would be depleted by competitive exclusion, locally. The disruptive effect of biomass dispersal thus acts to increase microbial diversity, allowing system-scale coexistence of multiple species that would not coexist locally.