Influence of anisotropic ion shape, asymmetric valency, and electrolyte concentration on structural and thermodynamic properties of an electric double layer

Grand canonical Monte Carlo simulation results are reported for an electric double layer modelled by a planar charged hard wall, anisotropic shape cations, and spherical anions at different electrolyte concentrations and asymmetric valencies. The cations consist of two tangentially tethered hard spheres of the same diameter, $d$. One sphere is charged while the other is neutral. Spherical anions are charged hard spheres of diameter $d$. The ion valency asymmetry 1:2 and 2:1 is considered, with the ions being immersed in a solvent mimicked by a continuum dielectric medium at standard temperature. The simulations are carried out for the following electrolyte concentrations: 0.1, 1.0 and 2.0 M. Profiles of the electrode-ion, electrode-neutral sphere singlet distributions, the average orientation of dimers, and the mean electrostatic potential are calculated for a given electrode surface charge, $\sigma$, while the contact electrode potential and the differential capacitance are presented for varying electrode charge. With an increasing electrolyte concentration, the shape of differential capacitance curve changes from that with a minimum surrounded by maxima into that of a distorted single maximum. For a 2:1 electrolyte, the maximum is located at a small negative $\sigma$ value while for 1:2, at a small positive value.Comment: 10 pages, 6 figure

Aggregation of microglia in 2D with string gradient weighted moving finite elements

Alzheimer's disease (AD) is a severe neurodegenerative disorder characterised by cognitive impairment and dementia. In the AD-affected brain, microglia cells are up-regulated and accumulate at senile plaques, the most prominent pathological feature of AD. In order to further study and predict the movement of activated microglia, we utilised their chemotactic properties. Specifically, we formulated the string gradient weighted moving finite element method for a system of partial differential equations in two dimensions, which includes nonlinear diffusion of a different variable found in chemotaxis models. The method was applied successfully to solve highly nonlinear chemorepulsion-chemorepellent models in two dimensions, and the results were compared with one-dimensional results found previously in the literature. We conclude that the string gradient weighted moving finite element method is easily applied to chemotaxis models, in particular movement and aggregation of microglia, resulting in the ability to study the models extended in two dimensions efficiently. Our study highlights the feasibility and power of mathematical modelling to advance our understanding of pathophysiological processes in neurodegenerative diseases, including AD

Double layer for hard spheres with an off-center charge

Simulations for the density and potential profiles of the ions in the planar electrical double layer of a model electrolyte or an ionic liquid are reported. The ions of a real electrolyte or an ionic liquid are usually not spheres; in ionic liquids, the cations are molecular ions. In the past, this asymmetry has been modelled by considering spheres that are asymmetric in size and/or valence (viz., the primitive model) or by dimer cations that are formed by tangentially touching spheres. In this paper we consider spherical ions that are asymmetric in size and mimic the asymmetrical shape through an off-center charge that is located away from the center of the cation spheres, while the anion charge is at the center of anion spheres. The various singlet density and potential profiles are compared to (i) the dimer situation, that is, the constituent spheres of the dimer cation are tangentially tethered, and (ii) the standard primitive model. The results reveal the double layer structure to be substantially impacted especially when the cation is the counterion. As well as being of intrinsic interest, this off-center charge model may be useful for theories that consider spherical models and introduce the off-center charge as a perturbation.Comment: 11 pages, 7 figure

Acoustic cues to individuality in wild male adult African savannah elephants (Loxodonta africana).

The ability to recognize conspecifics plays a pivotal role in animal communication systems. It is especially important for establishing and maintaining associations among individuals of social, long-lived species, such as elephants. While research on female elephant sociality and communication is prevalent, until recently male elephants have been considered far less social than females. This resulted in a dearth of information about their communication and recognition abilities. With new knowledge about the intricacies of the male elephant social structure come questions regarding the communication basis that allows for social bonds to be established and maintained. By analyzing the acoustic parameters of social rumbles recorded over 1.5 years from wild, mature, male African savanna elephants (Loxodonta africana) we expand current knowledge about the information encoded within these vocalizations and their potential to facilitate individual recognition. We showed that social rumbles are individually distinct and stable over time and therefore provide an acoustic basis for individual recognition. Furthermore, our results revealed that different frequency parameters contribute to individual differences of these vocalizations

Acoustic cues to individuality in wild male adult African savannah elephants (Loxodonta africana)

The ability to recognize conspecifics plays a pivotal role in animal communication systems. It is especially important for establishing and maintaining associations among individuals of social, long-lived species, such as elephants. While research on female elephant sociality and communication is prevalent, until recently male elephants have been considered far less social than females. This resulted in a dearth of information about their communication and recognition abilities. With new knowledge about the intricacies of the male elephant social structure come questions regarding the communication basis that allows for social bonds to be established and maintained. By analyzing the acoustic parameters of social rumbles recorded over 1.5 years from wild, mature, male African savanna elephants (Loxodonta africana) we expand current knowledge about the information encoded within these vocalizations and their potential to facilitate individual recognition. We showed that social rumbles are individually distinct and stable over time and therefore provide an acoustic basis for individual recognition. Furthermore, our results revealed that different frequency parameters contribute to individual differences of these vocalizations

Bidirectional manipulation of gene expression in adipocytes using CRISPRa and siRNA

Objective: Functional investigation of novel gene/protein targets associated with adipocyte differentiation or function heavily relies on efficient and accessible tools to manipulate gene expression in adipocytes in vitro. Recent advances in gene-editing technologies such as CRISPR-Cas9 have not only eased gene editing but also greatly facilitated modulation of gene expression without altering the genome. Here, we aimed to develop and validate a competent in vitro adipocyte model of controllable functionality as well as multiplexed gene manipulation in adipocytes, using the CRISPRa “SAM” system and siRNAs to simultaneously overexpress and silence selected genes in the same cell populations. Methods: We introduced a stable expression of dCas9-VP64 and MS2-P65, the core components of the CRIPSRa SAM system, in mesenchymal C3H/10T1/2 cells through viral delivery and used guide RNAs targeting Pparγ2, Prdm16, Zfp423, or Ucp1 to control the expression of key genes involved in adipocyte differentiation and function. We additionally co-transfected mature adipocytes with sgRNA plasmids and siRNA to simultaneously up-regulate and silence selected genes. Quantitative gene expression, oxygen consumption, fluorescence-activated cell sorting and immunocytochemistry served as validation proxies in pre- or mature adipocytes. Results: CRISPRa SAM-mediated up-regulation of a key adipogenic gene, Pparγ2, was successfully achieved using selected sgRNAs targeting the Pparγ2 promoter region (i.e. up to 104 fold); this induction was long lasting and sufficient to promote adipogenesis. Furthermore, co-activation of Pparγ2 with either Prdm16 or Zfp423 transcripts drove distinct thermogenic gene expression patterns associated with increased or decreased oxygen consumption, respectively, mimicking typical characteristics of brite/beige or white cell lineages. Lastly, we demonstrated that up-regulation of endogenous genes in mature adipocytes was also easily and efficiently achieved using CRISPRa SAM, here exemplified by targeted Ucp1 overexpression (up to 4 × 103 fold), and that it was compatible with concomitant gene silencing using siRNA, allowing for bidirectional manipulation of gene expression in the same cell populations. Conclusions: We demonstrate that the CRISPRa SAM system can be easily adopted and used to efficiently manipulate gene expression in pre- and mature adipocytes in vitro. Moreover, we describe a novel methodological approach combining the activation of endogenous genes and siRNA-mediated gene silencing, thus providing a powerful tool to functionally decipher genetic factors controlling adipogenesis and adipocyte functions

Semantiske og pragmatiske aspekter ved trykklett visst

I denne artikkelen ser vi på betydningen til trykklett visst og viser hvordan man kan utføre korpusundersøkelser av semantiske og pragmatiske aspekter ved denne typen ikke-sannhetsfunksjonelle ord. Vi foreslår at de mange bruksmåtene for ordet kan sammenfattes under ett semantisk oppslag, og med utgangspunkt i relevansteorien (Sperber & Wilson 1995) viser vi hvordan denne semantikken interagerer med generelle prinsipper for pragmatisk beriking og fører til ulike fortolkninger i ulike kontekster. Vi hevder videre at enkelte pragmatisk betingede fortolkninger av visst opptrer så systematisk at de utgjør det Ariel (2008; 2010) kaller âprominente diskursmønstreâ, og vi argumenterer for at det å identifisere prominente diskursmønstre er viktig i studier av denne typen ord

Maximizing detection of dengue virus serotypes by a modified reverse transcription-polymerase chain reaction assay in India: presence of co-infection with multiple serotypes

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An introduction to the New Online Journal Club - 'Surgery in Africa', and the first summary of a module - Compartment syndrome and diagnostic tests

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Re‐analysis of late Quaternary dust mass accumulation rates in Serbia using new luminescence chronology for loess–palaeosol sequence at Surduk

Despite numerous palaeoenvironmental investigations of loess–palaeosol sequences across the Carpathian Basin, well‐dated high‐resolution records are scarce. This paper presents a new high‐resolution chronology for the loess‐palaeosol sequence at Surduk (Serbia), based on optically stimulated luminescence (quartz) and post‐infrared infrared stimulated luminescence (polymineral) dating. The presented record spans 53–19 ka, with primary loess deposition occurring after 52±2 ka, and differs from previously published chronologies that relied on less precise and now superseded dating protocols. Based on the new chronology, mass accumulation rates (MAR s) for Surduk were constructed and compared with sites in the Carpathian Basin. The results demonstrate that accumulation periods across this area are not consistent in timing or rates. The high‐resolution dating strategy identifies a disturbance in sediment deposition that occurred after 45±2 ka and implies that site contains a hiatus. Finally, we show samples that failed routine dose recovery and preheat plateau tests, and had low fast ratios. Supported by bulk sample geochemical analysis it is proposed that a potential abrupt source shift, during the Last Glacial Maximum, may be the cause of the anomalous luminescence behaviour