Electrowetting of liquid marbles

Electrowetting of water drops on structured superhydrophobic surfaces are known to cause an irreversible change from a slippy (Cassie-Baxter) to a sticky (Wenzel) regime. An alternative approach to using a water drop on a superhydrophobic surface to obtain a non-wetting system is to use a liquid marble on a smooth solid substrate. A liquid marble is a droplet coated in hydrophobic grains, which therefore carries its own solid surface structure as a conformal coating. Such droplets can be considered as perfect non-wetting systems having contact angles to smooth solid substrates of close to 180 degrees. In this work we report the electrowetting of liquid marbles made of water coated with hydrophobic lycopodium grains and show that the electrowetting is completely reversible. Marbles are shown to return to their initial contact angle for both ac and dc electrowetting and without requiring a threshold voltage to be exceeded. Furthermore, we provide a proof-of-principle demonstration that controlled motion of marbles on a finger electrode structure is possible

An index method of estimating relative population densities of the Common Vole (Microtus arvalis) at landscape scale

Many issues in fundamental and applied ecology require the use of sampling protocols at the sectoral or even regional scales at which many important ecological mechanisms occur. The lack of workable sampling methods at these scales is a major obstacle to the analysis and understanding of these mechanisms. We test the validity of an index method of estimating relative population densities, applicable along transects of several kilometers in length, for a population of Common Voles (Microtus arvalis). The results show that the index method of estimating relative density is weil adapted for monitoring variations in the abundance and spatial distribution of Common Vole populations and authorizes studies for a wide range of objectives and spatial scalesDe nombreuses questions d'écologie fondamentale ou appliquée imposent l'application de protocoles d'échantillonnage à des échelles sectorielles, voire régionales, auxquelles se réalisent de nombreux mécanismes écologiques mportants. L'absence de méthodes d'échantillonnage utilisables à ces échelles représente un obstacle majeur à l'analyse et à la compréhension de ces mécanismes, Pour une population de Campagnols des champs (Microlus aryalis) nous avons testé la validite d'une méthode d'estimation indiciaire en densité relative applicable le long de transect, plurikilométriques. Les résultats obtenus montrent que cette méthode d'estimation indiciaire en densité relative est bien adaptée au suivi des variations d'abondance et de distribution des populations du Campagnol des champs et autorise des études pour une grande diversité d'objectifs et d'échelles spatiales

Data-based estimates of interannual sea-air CO2 flux variations 1957-2020 and their relation to environmental drivers

This study considers year-to-year and decadal variations in as well as secular trends of the sea-air CO2 flux over the 1957-2020 period, as constrained by the pCO(2) measurements from the SOCATv2021 database. In a first step, we relate interannual anomalies in ocean-internal carbon sources and sinks to local interannual anomalies in sea surface temperature (SST), the temporal changes in SST (dSST/dt), and squared wind speed (u(2)), employing a multi-linear regression. In the tropical Pacific, we find interannual variability to be dominated by dSST/dt, as arising from variations in the upwelling of colder and more carbon-rich waters into the mixed layer. In the eastern upwelling zones as well as in circumpolar bands in the high latitudes of both hemispheres, we find sensitivity to wind speed, compatible with the entrainment of carbon-rich water during wind-driven deepening of the mixed layer and wind-driven upwelling. In the Southern Ocean, the secular increase in wind speed leads to a secular increase in the carbon source into the mixed layer, with an estimated reduction in the sink trend in the range of 17 % to 42 %. In a second step, we combined the result of the multi-linear regression and an explicitly interannual pCO(2)-based additive correction into a "hybrid" estimate of the sea-air CO2 flux over the period 1957-2020. As a pCO(2) mapping method, it combines (a) the ability of a regression to bridge data gaps and extrapolate into the early decades almost void of pCO(2) data based on process-related observables and (b) the ability of an auto-regressive interpolation to follow signals even if not represented in the chosen set of explanatory variables. The "hybrid" estimate can be applied as an ocean flux prior for atmospheric CO2 inversions covering the whole period of atmospheric CO2 data since 1957

Capillary filling with wall corrugations] Capillary filling in microchannels with wall corrugations: A comparative study of the Concus-Finn criterion by continuum, kinetic and atomistic approaches

We study the impact of wall corrugations in microchannels on the process of capillary filling by means of three broadly used methods - Computational Fluid Dynamics (CFD), Lattice-Boltzmann Equations (LBE) and Molecular Dynamics (MD). The numerical results of these approaches are compared and tested against the Concus-Finn (CF) criterion, which predicts pinning of the contact line at rectangular ridges perpendicular to flow for contact angles theta > 45. While for theta = 30, theta = 40 (no flow) and theta = 60 (flow) all methods are found to produce data consistent with the CF criterion, at theta = 50 the numerical experiments provide different results. Whilst pinning of the liquid front is observed both in the LB and CFD simulations, MD simulations show that molecular fluctuations allow front propagation even above the critical value predicted by the deterministic CF criterion, thereby introducing a sensitivity to the obstacle heigth.Comment: 25 pages, 8 figures, Langmuir in pres

A study to explore the professional conceptualization and challenges of self-management in children and adolescents with lymphedema

Background: The aim of this study was to explore the professional experience of caring for children and adolescents with lymphedema and to explore the way in which they understand and implement self-management strategies and the influence of their own self-efficacy beliefs on this process. Methods and Results: Participants were recruited during an educational camp for children with lymphedema. Three individual semistructured focus groups were undertaken in English, French, and Italian with simultaneous translation. Data were analyzed using interpretative phenomenological analysis (IPA). Analysis of the data produced three superordinate themes: professional concepts of self-management, professional practice, and redefining the cornerstone of lymphedema care. An additional seven subthemes were as follows: readiness to self-management, professional perspectives on self-management, defining success and treatment failure, emotional burden, traditional views on complex decongestive therapy, new ways to practice, and sole practitioner versus multidisciplinary teams. Conclusions: The purpose of the study was to explore the challenges professionals face when introducing self-management to children and adolescents with lymphedema and their parents and to explore their own sense of self-efficacy in approaching this. The research allowed in-depth discussion about the ways they conceptualize self-management and faced professional challenges. The research highlighted the need to define what is considered an acceptable outcome within a complex and uncertain condition and the self-management strategies that are needed to support this

Landscape effects on the population dynamics of small mammal communities: A preliminary analysis of prey-resource variations

This study aims at estimating the effect of landscape composition on the availability of small mammal preys (in terms of biomass) to predators on a sectorial scale (n x 1 km2). Four study sites, representative of different stages of agriculture intensification, were selected in eastern France according to landscape composition. The population dynarnics of Microtus arvalis, Arvicola terrestris, Clethrionomys glareolus and Apodemus sp. were monitored from 1992 to 1996 by using index methods and trapping. M. arvalis and A. terrestris population biomasses were stable in landscapes with low percentage of permanent grassland. M. arvalis populations displayed greater biomass variations with sharp declines in the sites where the proportion of permanent grassland to farmland was greater than 50 %. A. terrestris populations were very unstable in one study site where the proportion of permanent grassland to farmland was greater than 85 %. Synchronic patterns between M. arvalis populations and the populations of hedgerow rodents were suspected at sites with large fluctuations of M. arvalis: every decline of the populations of hedgerow rodents was concomitant with the M. arvalis decline. These results suggest that two kinds of ecological systems in terms of prey-resource variations for mammalian predators can be distinguished: (i) stable in landscapes with lower proportion of permanent grassland, and (ii) unstable, with grassland species crashes and synchronous declines of the rodent community, in landscapes with higher proportion of permanent grassland. Moreover, the population dynamics of small mammals were asynchronous between the four sites situated at relatively short distance (some tens kilometres)L'objectif de cette étude est d'estimer l'effet de la composition du paysage sur les variations de disponibilité en biomasse de micro-mammifères pour les prédateurs, à l'échelle sectorielle (n × 1 km2), Quatre sites d'étude représentatifs d'un gradient d'intensification agricole ont été choisis dans l'est de la France en fonction de la composition du paysage. Les fluctuations de biomasses de Microtus arvalis et Arvicola terrestris (espèces prairiales), de Clethrionomys glareolus et Apodemus sp. (espèces de milieux fermés) ont été suivies de 1992 à 1996 par méthodes indiciaires et piégeage. Les synchronies entre les populations de M. arvalis et celles de rongeurs de milieux fermés ont été recherchées. Les fluctuations de biomasse de M. arvalis et A. terrestris sont stables dans les sites où la proportion de prairie permanente est la plus faible. Les populations de M. arvalis présentent les plus larges amplitudes de variation de biomasse et les déclins les plus prononcés dans les sites où la proportion de prairie permanente sur la surface agricole est supérieure à 50 %. Les populations d'A. terrestris ne sont instables que dans un site, là où la proportion de prairie permanente sur surface agricole est supérieure à 85 %. Les déclins de populations de rongeurs de milieux fermés (Clethrionomys glareolus et Apodemus sp.) sont concomitants de ceux de M. arvalis dans les sites à fortes variations de biomasse de cette dernière espèce. Ces résultats suggèrent deux types de fonctionnement, en terme de variation de disponibilité en proies pour les prédateurs: (i) stable dans les paysages à faible proportion de prairie permanente, et (ii) instable, avec des déclins prononcés et rapides des populations d'espèces prairiales, entraînant des déclins synchrones du peuplement de micro-mammifères étudié, dans les paysages à forte proportion de prairie permanente. Aucune synchronie dans les dynamiques de population de ces micro-mammifères n'est observée entre les sites d'étude, éloignés de quelques dizaines de kilomètres seulement

Spallative ablation of dielectrics by X-ray laser

Short laser pulse in wide range of wavelengths, from infrared to X-ray, disturbs electron-ion equilibrium and rises pressure in a heated layer. The case where pulse duration $\tau_L$ is shorter than acoustic relaxation time $t_s$ is considered in the paper. It is shown that this short pulse may cause thermomechanical phenomena such as spallative ablation regardless to wavelength. While the physics of electron-ion relaxation on wavelength and various electron spectra of substances: there are spectra with an energy gap in semiconductors and dielectrics opposed to gapless continuous spectra in metals. The paper describes entire sequence of thermomechanical processes from expansion, nucleation, foaming, and nanostructuring to spallation with particular attention to spallation by X-ray pulse

Hydrophobic and metallophobic surfaces: Highly stable non-wetting inorganic surfaces based on lanthanum phosphate nanorods

Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO 4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO 4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO 4 and other REP ceramics utility in diverse applications