Nanoparticle transport modelling in saturated porous media

University of Technology, Sydney. Faculty of Engineering and Information Technology.This research deals with multi-scale descriptions of nano-colloidal transport in saturated porous media. Colloidal transport has been simulated, historically, by employing a pore-scale model. I argue that the use of such simulations on a continuum-scale where formulations are generally phenomenological, may be unsuitable if at all possible due to requirements for pore-scale parameterization. I propose to up-scale the pore-scale equation by inclusion of natural heterogeneity of porous media which consequently substitutes the pore-scale parameters (often unobtainable in real cases) with continuum-scale parameters (measurable at field). This approach transforms the pore-scale formulation into a Darcy-scale formulation, making it usable for real-world simulations. I demonstrate a closer agreement with experimental data once porous media’s natural heterogeneity is considered compared with the use of a mean value for media grain size in the conventional methods. These results can be explained by noting the fact that hydraulic conductivity of a porous medium is not controlled by the coarser or the median size grains. Rather, it is the smaller grains which ultimately determine (or in other words, restrict) the permeability of any given porous medium. By comparing various modelled scenarios, I also assess the magnitude of difference in predicted results which displays a significant divergence from the case where the porous medium is assumed to be homogeneous. Finally I aim to estimate the uncertainty associated with scenarios A (Yao’s equation) and B (Mehrabi_ Milne-Home equation) in the absence and presence of natural heterogeneity, respectively. The results showed a noticeable decrease of 9% to 87% in the uncertainty caused by the most prominent source of uncertainty in groundwater modelling; porous media’s heterogeneity. The uncertainty is generally lower closer to the contaminant release point and increases as the plume moves away from the source point. The more substantial improvements (reduction of uncertainty) was observed at selected point which were located further away from the release point. A framework for the assessment of nanoparticle transport in aquifers follows in which the extent of movement is estimated based on available field measured data and the probabilities of various potential realizations can be measured. This will help provide a much needed set of information for the policy-making processes with regards to new and emerging contaminants including engineered nanoparticles

Dark energy reconstruction based on the PADE approximation; an expansion around the Λ\LambdaCDM

We study the dynamical properties of dark energy based on a large family of PADE parameterizations for which the dark energy density evolves as a ratio between two polynomials in the scale factor of the universe. Using the latest cosmological data we perform a standard likelihood analysis in order to place constraints on the main cosmological parameters of different PADE models. We find that the basic cosmological parameters, namely $(\Omega_{m0},h,\sigma_{8})$ are practically the same for all PADE parametrizations explored here. Concerning the free parameters which are related to dark energy we show that the best fit values indicate that the equation of state parameter at the present time is in the phantom regime ($w-1$ at $1\sigma$ level. Finally, for the current family of PADE parametrizations we test their ability, via AIC and Jeffreys' scale, to deviate from $\Lambda$CDM cosmology. Among the current PADE parametrizations, the model which contains two dark energy parameters is the one for which a small but non-zero deviation from $\Lambda$CDM cosmology is slightly allowed by AIC test. Moreover, based on Jeffreys' scale we show that a deviation from $\Lambda$CDM cosmology is also allowed and thus the possibility of having a dynamical dark energy in the form of PADE parametrization cannot be excluded.Comment: Accepted for publication in EPJ

Correction: Vocal imitation of percussion sounds: On the perceptual similarity between imitations and imitated sounds

[This corrects the article DOI: 10.1371/journal.pone.0219955.]

Active role of the necrotic zone in desensitization of hypoxic macrophages and regulation of CSC-fate: A hypothesis

Fast-proliferating cancer cells in the hypoxic region face a shortage of oxygen and nutrients, undergo necrotic cell death, and release numerous signaling components. Hypoxia-induced chemo-attractants signal for macrophages/monocytes to clear debris and return the system to steady state. Accordingly, macrophages arrange into pre-necrotic positions, where they are continuously exposed to stress signals. It can thus be hypothesized that gradual alteration of gene expression in macrophages eventually turns offtheir phagocytic machinery. Uncleared cell corpses within the hypoxic region potentially provide a rich source of building blocks for anaerobic metabolism of cancer stem cells via macropinocytosis, and are conceivably implicated in tumor progression and invasion. © 2018 Mehrabi, Amini and Mehrabi

Commensalism and parasitic infestation in crayfish (Astacus leptodactylus Eschscholtz, 1823) of Aras Dam Reservoir, Iran

The freshwater crayfish of the Aras Reservoir is an important economic fisheries resource of West Azarbaijan, Iran. This study was conducted to evaluate the prevalence of parasitic infestation of Crayfish seasonally in this area in 2010. Among 390 different sizes of Astacus leptodactylus which were examined, a range of ectocommensals or ectosymbionts from a number of different phyla including 9 orders and 11 classes infested the different anatomic units of the surface and appendages such as gills, head, thorax, abdomen, walking legs, uropod, telson, antennae and antennulae of freshwater crayfish. Common groups such as peritrich ciliates, suctorian ciliates, free living nematodes, branchiobdellids, and algae, copepods, rotifers and oligochaetes have also been observed in association with freshwater crayfish

Ga and Gß Proteins Regulate the Cyclic AMP Pathway That Is Required for Development and Pathogenicity of the Phytopathogen Mycosphaerella graminicola

We identified and functionally characterized genes encoding three G alpha proteins and one G beta protein in the dimorphic fungal wheat pathogen Mycosphaerella graminicola, which we designated MgGpa1, MgGpa2, MgGpa3, and MgGpb1, respectively. Sequence comparisons and phylogenetic analyses showed that MgGPA1 and MgGPA3 are most related to the mammalian G alpha(i) and G alpha(s) families, respectively, whereas MgGPA2 is not related to either of these families. On potato dextrose agar (PDA) and in yeast glucose broth (YGB), MgGpa1 mutants produced significantly longer spores than those of the wild type (WT), and these developed into unique fluffy mycelia in the latter medium, indicating that this gene negatively controls filamentation. MgGpa3 mutants showed more pronounced yeast-like growth accompanied with hampered filamentation and secreted a dark-brown pigment into YGB. Germ tubes emerging from spores of MgGpb1 mutants were wavy on water agar and showed a nested type of growth on PDA that was due to hampered filamentation, numerous cell fusions, and increased anastomosis. Intracellular cyclic AMP (cAMP) levels of MgGpb1 and MgGpa3 mutants were decreased, indicating that both genes positively regulate the cAMP pathway, which was confirmed because the WT phenotype was restored by adding cAMP to these mutant cultures. The cAMP levels in MgGpa1 mutants and the WT were not significantly different, suggesting that this gene might be dispensable for cAMP regulation. In planta assays showed that mutants of MgGpa1, MgGpa3, and MgGpb1 are strongly reduced in pathogenicity. We concluded that the heterotrimeric G proteins encoded by MgGpa3 and MgGpb1 regulate the cAMP pathway that is required for development and pathogenicity in M. graminicola

Evaluation of the effects of different concentrations of neutral anolyte on fungal infected eggs in rainbow trout (Oncorhynchus mykiss) in comparison with green malachite

The objective of this study was to determine the effect of different concentrations of anolyte on saprolegniasis in comparison with green malachite in rainbow trout hatcheries, in the northern part of Iran, Tonekabon. Nearly 5000 green eggs of Oncorhynchus mykiss (equivalent to 300 g) were obtained from a private farm in the north of Iran. The study was designed in 5 treatments, 0.25, 0.5, 30 and 100 ppm of neutral anolyte and 2 ppm of green malachite and two controls including positive control, meaning that the green eggs were purposely infected with saprolegnia but without any disinfectant, and negative control, which was implied to as the untreated group, all in triplicate. There was no significant difference (α>0.05) in hatchability percent between 2 ppm of green malachite and the group treated with 0.25 ppm of neutral anolyte, contrary to other anolyte concentrations. It is concluded that constant use of 0.25 ppm of neutral electrolyzed oxidized water (NEOW) is a more effective anti-fungal solution with the least side effects in comparison with 2 ppm of green malachite