A lattice model for the line tension of a sessile drop

Within a semi--infinite thre--dimensional lattice gas model describing the coexistence of two phases on a substrate, we study, by cluster expansion techniques, the free energy (line tension) associated with the contact line between the two phases and the substrate. We show that this line tension, is given at low temperature by a convergent series whose leading term is negative, and equals 0 at zero temperature

Crucial role of sidewalls in velocity distributions in quasi-2D granular gases

Our experiments and three-dimensional molecular dynamics simulations of particles confined to a vertical monolayer by closely spaced frictional walls (sidewalls) yield velocity distributions with non-Gaussian tails and a peak near zero velocity. Simulations with frictionless sidewalls are not peaked. Thus interactions between particles and their container are an important determinant of the shape of the distribution and should be considered when evaluating experiments on a tightly constrained monolayer of particles.Comment: 4 pages, 4 figures, Added reference, model explanation charified, other minor change

Layering in the Ising model

We consider the three-dimensional Ising model in a half-space with a boundary field (no bulk field). We compute the low-temperature expansion of layering transition lines

Theoretical Characterization of the Interface in a Nonequilibrium Lattice System

The influence of nonequilibrium bulk conditions on the properties of the interfaces exhibited by a kinetic Ising--like model system with nonequilibrium steady states is studied. The system is maintained out of equilibrium by perturbing the familiar spin--flip dynamics at temperature T with completely--random flips; one may interpret these as ideally simulating some (dynamic) impurities. We find evidence that, in the present case, the nonequilibrium mechanism adds to the basic thermal one resulting on a renormalization of microscopic parameters such as the probability of interfacial broken bonds. On this assumption, we develop theory for the nonequilibrium "surface tension", which happens to show a non--monotonous behavior with a maximum at some finite T. It ensues, in full agreement with Monte Carlo simulations, that interface fluctuations differ qualitatively from the equilibrium case, e.g., the interface remains rough at zero--T. We discuss on some consequences of these facts for nucleation theory, and make some explicit predictions concerning the nonequilibrium droplet structure.Comment: 10 pages, 7 figures, submitted to Phys. Re

Oxygen impurities in NiAl: Relaxation effects

We have used a full-potential linear muffin-tin orbital method to calculate the effects of oxygen impurities on the electronic structure of NiAl. Using the supercell method with a 16-atom supercell we have investigated the cases where an oxygen atom is substitutionally placed at either a nickel or an aluminum site. Full relaxation of the atoms within the supercell was allowed. We found that oxygen prefers to occupy a nickel site over an aluminum site with a site selection energy of 138 mRy (21,370 K). An oxygen atom placed at an aluminum site is found to cause a substantial relaxation of its nickel neighbors away from it. In contrast, this steric repulsion is hardly present when the oxygen atom occupies the nickel site and is surrounded by aluminum neighbors. We comment on the possible relation of this effect to the pesting degradation phenomenon (essentially spontaneous disintegration in air) in nickel aluminides.Comment: To appear in Phys. Rev. B (Aug. 15, 2001

Cluster expansion for abstract polymer models. New bounds from an old approach

We revisit the classical approach to cluster expansions, based on tree graphs, and establish a new convergence condition that improves those by Kotecky-Preiss and Dobrushin, as we show in some examples. The two ingredients of our approach are: (i) a careful consideration of the Penrose identity for truncated functions, and (ii) the use of iterated transformations to bound tree-graph expansions.Comment: 16 pages. This new version, written en reponse to the suggestions of the referees, includes more detailed introductory sections, a proof of the generalized Penrose identity and some additional results that follow from our treatmen

The HABIT (HabitAbility: Brine Irradiation and Temperature) environmental instrument for the ExoMars 2022 Surface Platform

Acknowledgements HABIT is an instrument of the Luleå University of Technology (LTU), led by J. Martín-Torres (PI) and M-P. Zorzano (co-PI). The international list of Co-Is and collaborators of the science team of HABIT is given in (https://atmospheres.research.ltu.se/habit/pages/team.php). HABIT engineering team: A. Soria-Salinas, M. I. Nazarious, S. Konatham, T. Mathanlal and A. Vakkada Ramachandran. HABIT IT team: J. –A. Ramirez-Luque and R. Mantas-Nakhai. ASS acknowledges the support of the LTU Graduate School of Space. M-P. Z's contribution has been partially supported by the Spanish State Research Agency (AEI) Project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu” - Centro de Astrobiología (INTA-CSIC). The HABIT FM and EQM were fabricated by Omnisys Instruments AB, based in Gothenburg, Sweden, under advice of LTU as part of the HABIT project development and funded by the Swedish National Space Agency (SNSA). We thank the ExoMars project team, European Space Agency (ESA), Roscosmos, Space Research Institute (IKI) and Omnisys Instruments AB for their hard work on the ExoMars mission. We thank Petra Rettberg and Carina Fink from DLR for their planetary protection analysis of HABIT samples. We acknowledge the Luleå University of Technology, the Wallenberg Foundation and the Kempe Foundation for support of the Mars research activities. We thank the support of the Swedish Institute for Space Physics (IRF) for the TVAC tests. The Oxia Planum environmental conditions research was partially funded by the European Research Foundation. The SpaceQ chamber has been developed together with Kurt J. Lesker Company and was funded by the Kempe Foundation. CRediT authorship contribution statement Javier Martín-Torres: Conceptualization, Methodology, Supervision, Investigation, Writing - original draft, Funding acquisition, Resources, Project administration. María-Paz Zorzano: Conceptualization, Methodology, Supervision, Investigation, Writing - original draft, Funding acquisition, Resources, Project administration. Álvaro Soria-Salinas: Formal analysis, Investigation, Visualization, Writing - review & editing. Miracle Israel Nazarious: Formal analysis, Investigation, Visualization, Writing - review & editing. Samuel Konatham: Formal analysis, Investigation, Visualization, Writing - review & editing. Thasshwin Mathanlal: Formal analysis, Investigation, Visualization, Writing - review & editing. Abhilash Vakkada Ramachandran: Formal analysis, Investigation, Visualization, Writing - review & editing. Juan-Antonio Ramírez-Luque: Software, Writing - review & editing. Roberto Mantas-Nakhai: Software, Writing - review & editing.Peer reviewedPostprin

Evidence of temperature-dependent effects on the estrogenic response of fish: implications with regard to climate change

The official published version can be obtained from the link below - Copyright @ 2008 Elsevier BV.Chemical risk assessment is fraught with difficulty due to the problem of accounting for the effects of mixtures. In addition to the uncertainty arising from chemical-to-chemical interactions, it is possible that environmental variables, such as temperature, influence the biological response to chemical challenge, acting as confounding factors in the analysis of mixture effects. Here, we investigate the effects of temperature on the response of fish to a defined mixture of estrogenic chemicals. It was anticipated that the response to the mixture may be exacerbated at higher temperatures, due to an increase in the rate of physiological processing. This is a pertinent issue in view of global climate change. Fathead minnows (Pimephales promelas) were exposed to the mixture in parallel exposure studies, which were carried out at different temperatures (20 and 30 degrees C). The estrogenic response was characterised using an established assay, involving the analysis of the egg yolk protein, vitellogenin (VTG). Patterns of VTG gene expression were also analysed using real-time QPCR. The results revealed that there was no effect of temperature on the magnitude of the VTG response after 2 weeks of chemical exposure. However, the analysis of mixture effects at two additional time points (24 h and 7 days) revealed that the response was induced more rapidly at the higher temperature. This trend was apparent from the analysis of effects both at the molecular and biochemical level. Whilst this indicates that climatic effects on water temperature are not a significant issue with regard to the long-term risk assessment of estrogenic chemicals, the relevance of short-term effects is, as yet, unclear. Furthermore, analysis of the patterns of VTG gene expression versus protein induction gives an insight into the physiological mechanisms responsible for temperature-dependent effects on the reproductive phenology of species such as roach. Hence, the data contribute to our understanding of the implications of global climate change for wild fish populations.This work was funded by a grant from the Natural Environment Research Council NE/D00389X/1). Additional support was provided by a small research grant from the Fisheries Society of the British Isles