Prewetting transitions of Ar and Ne on alkali metal surfaces

We have studied by means of Density-Functional calculations the wetting properties of Ar and Ne adsorbed on a plane whose adsorption properties simulate the Li and Na surfaces. We use reliable ab-initio potentials to model the gas-substrate interactions. Evidence for prewetting transitions is found for all the systems investigated and their wetting phase diagrams are calculated.Comment: 6 pages, 8 figures, submitted for publication in Phys. Rev.

To wet or not to wet: that is the question

Wetting transitions have been predicted and observed to occur for various combinations of fluids and surfaces. This paper describes the origin of such transitions, for liquid films on solid surfaces, in terms of the gas-surface interaction potentials V(r), which depend on the specific adsorption system. The transitions of light inert gases and H2 molecules on alkali metal surfaces have been explored extensively and are relatively well understood in terms of the least attractive adsorption interactions in nature. Much less thoroughly investigated are wetting transitions of Hg, water, heavy inert gases and other molecular films. The basic idea is that nonwetting occurs, for energetic reasons, if the adsorption potential's well-depth D is smaller than, or comparable to, the well-depth of the adsorbate-adsorbate mutual interaction. At the wetting temperature, Tw, the transition to wetting occurs, for entropic reasons, when the liquid's surface tension is sufficiently small that the free energy cost in forming a thick film is sufficiently compensated by the fluid- surface interaction energy. Guidelines useful for exploring wetting transitions of other systems are analyzed, in terms of generic criteria involving the "simple model", which yields results in terms of gas-surface interaction parameters and thermodynamic properties of the bulk adsorbate.Comment: Article accepted for publication in J. Low Temp. Phy

Wetting films on chemically heterogeneous substrates

Based on a microscopic density functional theory we investigate the morphology of thin liquidlike wetting films adsorbed on substrates endowed with well-defined chemical heterogeneities. As paradigmatic cases we focus on a single chemical step and on a single stripe. In view of applications in microfluidics the accuracy of guiding liquids by chemical microchannels is discussed. Finally we give a general prescription of how to investigate theoretically the wetting properties of substrates with arbitrary chemical structures.Comment: 56 pages, RevTeX, 20 Figure

Climate-driven range extension of Amphistegina (protista, foraminiferida) : models of current and predicted future ranges

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS ONE 8 (2013): e54443, doi:10.1371/journal.pone.0054443.Species-range expansions are a predicted and realized consequence of global climate change. Climate warming and the poleward widening of the tropical belt have induced range shifts in a variety of marine and terrestrial species. Range expansions may have broad implications on native biota and ecosystem functioning as shifting species may perturb recipient communities. Larger symbiont-bearing foraminifera constitute ubiquitous and prominent components of shallow water ecosystems, and range shifts of these important protists are likely to trigger changes in ecosystem functioning. We have used historical and newly acquired occurrence records to compute current range shifts of Amphistegina spp., a larger symbiont-bearing foraminifera, along the eastern coastline of Africa and compare them to analogous range shifts currently observed in the Mediterranean Sea. The study provides new evidence that amphisteginid foraminifera are rapidly progressing southwestward, closely approaching Port Edward (South Africa) at 31°S. To project future species distributions, we applied a species distribution model (SDM) based on ecological niche constraints of current distribution ranges. Our model indicates that further warming is likely to cause a continued range extension, and predicts dispersal along nearly the entire southeastern coast of Africa. The average rates of amphisteginid range shift were computed between 8 and 2.7 km year−1, and are projected to lead to a total southward range expansion of 267 km, or 2.4° latitude, in the year 2100. Our results corroborate findings from the fossil record that some larger symbiont-bearing foraminifera cope well with rising water temperatures and are beneficiaries of global climate change.This work was supported by grants from the German Science Foundation (DFG; www.dfg.de) to ML and SL (LA 884/10-1, LA 884/5-1)

Small Changes in the Primary Structure of Transportan 10 Alter the Thermodynamics and Kinetics of its Interaction with Phospholipid Vesicles

ABSTRACT: The kinetics and thermodynamics of binding of transportan 10 (tp10) and four of its variants to phospholipid vesicles, and the kinetics of peptide-induced dye efflux, were compared. Tp10 is a 21-residue, amphipathic, cationic, cell-penetrating peptide similar to helical antimicrobial peptides. The tp10 variants examined include amidated and free peptides, and replacements of tyrosine by tryptophan. Carboxy-terminal amidation or substitution of tryptophan for tyrosine enhance binding and activity. The Gibbs energies of peptide binding to membranes determined experimentally and calculated from the interfacial hydrophobicity scale are in good agreement. The Gibbs energy for insertion into the bilayer core was calculated using hydrophobicity scales of residue transfer from water to octanol and to the membrane/ water interface. Peptide-induced efflux becomes faster as the Gibbs energies for binding and insertion of the tp10 variants decrease. If anionic lipids are included, binding and efflux rate increase, as expected because all tp10 variants are cationic and an electrostatic component is added. Whether the most important effect of peptide amidation is the change in charge or an enhancement of helical structure, however, still needs to be established. Nevertheless, it is clear that the changes in efflux rate reflect the differences in the thermodynamics of binding and insertion of the free and amidated peptide groups. We have recently reported a detailed investigation (1) o

Non-factorizable contributions in hadronic weak decays of charm mesons

Two body decays of charm mesons are studied by describing their amplitude in terms of a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is calculated by using a hard pseudo-scalar-meson approximation. The hard pseudo-scalar-meson amplitude is given by a sum of the so-called equal-time commutator term and surface term which contains all possible pole contributions of various mesons, not only the ordinary $\{q\bar q\}$ but also four-quark $\{qq\bar q\bar q\}$, hybrid $\{q\bar qg\}$ and glue-balls. Naively factorized amplitudes for the spectator decays which lead to too big rates can interfere destructively with exotic meson pole amplitudes and the total amplitudes can reproduce their observed rates. The non-factorizable contributions can supply sufficiently large contributions to the color suppressed decays which are strongly suppressed in the naive factorization. A possible solution to the long standing puzzle that the ratio of decay rates for $D^0\to K^+K^-$ to $D^0\to \pi^+\pi^-$ is around 2.5 is given by different contributions of exotic meson poles.Comment: 22 pages, RevTe

The nucleus reuniens: a key node in the neurocircuitry of stress and depression

Uncorrected proofThe hippocampus and prefrontal cortex (PFC) are connected in a reciprocal manner: whereas the hippocampus projects directly to the PFC, a polysynaptic pathway that passes through the nucleus reuniens (RE) of the thalamus relays inputs from the PFC to the hippocampus. The present study demonstrates that lesioning and/or inactivation of the RE reduces coherence in the PFC-hippocampal pathway, provokes an antidepressant-like behavioral response in the forced swim test and prevents, but does not ameliorate, anhedonia in the chronic mild stress (CMS) model of depression. Additionally, RE lesioning before CMS abrogates the well-known neuromorphological and endocrine correlates of CMS. In summary, this work highlights the importance of the reciprocal connectivity between the hippocampus and PFC in the establishment of stress-induced brain pathology and suggests a role for the RE in promoting resilience to depressive illness.Greece for providing sertraline. This work was supported by an ‘Education and Lifelong Learning, Supporting Postdoctoral Researchers’, co-financed by the European Social Fund (ESF) and the General Secretariat for Research and Technology, Greece, the Life and Health Sciences Research Institute (ICVS), ON.2—O NOVO NORTE—North Portugal Regional Operational Program 2007/2013 of the National Strategic Reference Framework (NSRF) 2007/2013 through the European Regional Development Fund (ERDF), the Portuguese Foundation for Science and Technology (FCT; grant no. NMC-113934) and an InEurope program funded by International Brain Research Organizationinfo:eu-repo/semantics/publishedVersio

Linking Proteomic and Transcriptional Data through the Interactome and Epigenome Reveals a Map of Oncogene-induced Signaling

Cellular signal transduction generally involves cascades of post-translational protein modifications that rapidly catalyze changes in protein-DNA interactions and gene expression. High-throughput measurements are improving our ability to study each of these stages individually, but do not capture the connections between them. Here we present an approach for building a network of physical links among these data that can be used to prioritize targets for pharmacological intervention. Our method recovers the critical missing links between proteomic and transcriptional data by relating changes in chromatin accessibility to changes in expression and then uses these links to connect proteomic and transcriptome data. We applied our approach to integrate epigenomic, phosphoproteomic and transcriptome changes induced by the variant III mutation of the epidermal growth factor receptor (EGFRvIII) in a cell line model of glioblastoma multiforme (GBM). To test the relevance of the network, we used small molecules to target highly connected nodes implicated by the network model that were not detected by the experimental data in isolation and we found that a large fraction of these agents alter cell viability. Among these are two compounds, ICG-001, targeting CREB binding protein (CREBBP), and PKF118–310, targeting β-catenin (CTNNB1), which have not been tested previously for effectiveness against GBM. At the level of transcriptional regulation, we used chromatin immunoprecipitation sequencing (ChIP-Seq) to experimentally determine the genome-wide binding locations of p300, a transcriptional co-regulator highly connected in the network. Analysis of p300 target genes suggested its role in tumorigenesis. We propose that this general method, in which experimental measurements are used as constraints for building regulatory networks from the interactome while taking into account noise and missing data, should be applicable to a wide range of high-throughput datasets.National Science Foundation (U.S.) (DB1-0821391)National Institutes of Health (U.S.) (Grant U54-CA112967)National Institutes of Health (U.S.) (Grant R01-GM089903)National Institutes of Health (U.S.) (P30-ES002109