Simulation of Pendant Droplet Behavior on Plain and Patterned Surfaces using Surface Evolver

In this work, pendant droplets of different liquids (i.e. water, ethylene glycol, methanol, and acetone) on a plain aluminum surface and a three-stripe patterned surface were simulated using the Surface Evolver (SE) software. The critical droplet volume before detachment from a surface and droplet properties such as diameter, height, and surface energy were measured. Surface Evolver is a program that models liquid surfaces shaped by different forces and constraints. The program works by modifying a surface toward minimal thermodynamic energy by a gradient descent method. The initial input to Surface Evolver is a script file containing all the pertinent information about the droplet to be simulated including the gravitational constant, volume, density, and contact angle. For these simulations, the gravitational constant was set to -1 for all liquids (i.e. 9.81 m s-2), and the values of density and contact angle were based on the simulated liquid type. As part of this study, droplet contact angles were measured on an aluminum surface at room temperature (~20°C), and these values were used as inputs in the simulation. The measured static contact angle for water, ethylene glycol, methanol, and acetone were found to be 88.2 ,°61.0 ,°20.9°, and 13.0°, respectively. For each simulation, more than 100 iterations were performed before the droplet geometry converged and was ready for measurement. The surface energy was taken directly after each iteration, while the droplet height and diameter were calculated from simulation pictures using a pixel counting method. The critical pendant droplet volumes for water, ethylene glycol, methanol, and acetone on a plain aluminum surface were found to be 17.9, 21, 19.03, and 14 μL, respectively. For the purposes of this study, the critical volume (i.e. when the droplet starts detaching) was defined when the surface energy was found to be in the range of -0.15 J to 0.15 J. Besides critical volumes, droplet data associated with smaller volumes (i.e. 5, 8, 10, 12, and 15 μL) were also measured and compared among liquids. Patterned surfaces were also studied in this work. These surfaces consisted of a central hydrophilic stripe varying from 1 mm to 5 mm in width sandwiched between two outer hydrophobic regions. Critical droplet volumes on these surfaces are also discussed

Water Condensation and Droplet Shedding Behavior on Silica Nanospring Coated Tubes

In this work, an amorphous silica nanospring (SN) coating is considered as a method to induce hydrophobicity and dropwise condensation on aluminum tubes for both water and methanol. Silica nanosprings offer several advantages over other one-dimensional nanostructures including high surface area (350 m2 g-1), mild growth conditions (350°C, atmospheric pressure), and thermal stability (\u3c 1000°C in air). Special focus in this work will be given to baseline testing and the performance of functionalized SN tubes. Testing to investigate the performance of SN-coated tubes and compare against the performance of uncoated tubing will be conducted in a purpose-built environmental chamber. In order to increase the amount of heat transfer possible within this chamber, 3D-printed fluid-carrying manifolds were designed to significantly increase the amount of available tube surface area. Two different methods of calculating condensation heat transfer coefficients from collected data are compared. Additionally, the existence of an ideal SN coating thickness for maximizing heat transfer and condensation rate is investigated. Future work will focus on using the printed and optimized manifolds to collect data from both a set of uncoated and sets of SN-coated tubes

Defrosting Performance of Patterned Heat Transfer Surfaces with a Superhydrophobic Silica Nanosprings Coating

The overall aim of this work was to study the defrosting performance of functionalized heat transfer surfaces containing a novel, silica nanosprings coating combined with preferential microstructural roughness. In doing this, differences in drainage rates and defrosting effectiveness were explored both on patterned and non-patterned surfaces. To date, ten different surfaces have been examined— an uncoated, untreated aluminum plate (S1), plates containing a silica nanospring (SN) coating of varying thickness (S2-S6), a plate containing evenly-spaced microchannels both with and without the SN surface coating (S7, S8), and then finally a plate containing a microstructural roughness gradient both with and without the SN surface coating (S9, S10). Cyclical tests containing both frosting and defrosting periods were conducted on each sample. For these experiments, the frost layer was grown inside a controlled environmental test chamber where the relative humidity (RH) was held constant (i.e. 60%, 80%) while the temperature of the ambient air inside the enclosure was monitored to ensure consistency. The surface temperature of the plate was fixed using a thermoelectric cooler (TEC) typically at -8°C, -10°C or -12°C. The TEC unit was placed on an electronic balance within the test chamber, which permitted the frost mass to be recorded continuously during testing. Overall, the defrosting effectiveness varied from 56-96% across all the surfaces depending on the test conditions. For the tests performed at 60% RH, the uncoated baseline surfaces tended to have defrosting efficiencies in the range of 59-75%, while the nanospring-coated surfaces tended to have defrosting efficiencies in the range of 66-96%. Different nanospring mat thicknesses were also explored as part of this work, which showed that an optimum thickness likely exists with shorter overall mat thicknesses being preferred. The microstructural surface gradient pattern included in this work was designed to create “preferential lanes” on the surface for drainage. The surface which yielded the highest overall defrosting efficiency during testing was the surface with the uniformly-spaced microchannels and nanospring coating (S8), while the gradient surface design with nanospring coating (S10) also generally performed well versus the baseline surface, especially at lower plate temperatures (i.e. Tw = -10 and -12°C)

MICROWAVE-ASSISTED BRUCITE AND TALC REACTIONS WITH CO2 AS A PROXY FOR CARBON CAPTURE AND STORAGE BY SERPENTINE

In the last decades many studies have been focusing on Carbon Capture and Storage (CCS) to find a possible remedy to reduce the large increase of anthropogenic carbon dioxide (CO ). Mineral Carbonation (MC) is a potential solution for almost irreversible chemical long-term CCS. It concerns the combination of CaO and MgO with CO forming spontaneously and exothermically dolomite and magnesite. However, kinetic barriers pose sever limitations for the practical exploitation of this reaction. High fractions of MgO are available in silicates such as olivine, orthopyroxene, clinopyroxene and serpentine. To date, data reported that serpentine polymorphs, above all antigorite, is an excellent candidate for fixing the CO as the reaction efficiency is approximately 92% compared to lizardite (40%) and olivine (66%). This is due to the surface reactivity of approximately 18.7 m /g for the dehydrated antigorite compared to10.8 m /g for dehydrated lizardite and 4.6 m /g for olivine. The microwave assisted process for CCS is an innovative technology that can be employed to catalyze the reaction through thermal and non-thermal mechanisms. Some pioneering tests of direct carbonation by microwave hydrothermal equipment have been performed on olivine, lizardite and chrysotile powders [1] but not on antigorite. The structure of serpentine is characterized by corrugated stacked layers of silica and brucite. For this reason, MC involves dissolution of SiO layers, dissolution/dehydration of Mg(OH) layers, and precipitation of magnesium carbonate. To address the chemical response of the single phases, experiments have been performed by both a local microwave-source acting locally on a specific crystal surface and a volume source interacting with an ensemble of grains on synthetic powders and single crystals of pure brucite and talc. In a second step, treatments have been extended to chrysotile, lizardite and antigorite. A characterization of the mechanism and kinetics were performed by scanning probe microscopy on the surface of single crystals phases, supported by Raman spectroscopy and by Scanning and Transmission Electron Microscopy study performed on micro- and nano-sized grains. [1] White, et al. Reaction mechanisms of magnesium silicates with carbon dioxide in microwave fields. Final Report to the U.S. Department ofEnergy, National Energy Technology Laboratory (2004

Managing chronic pathologies with a stepped mHealth-based approach in clinical psychology and medicine

Chronic diseases and conditions typically require long-term monitoring and treatment protocols both in traditional settings and in out-patient frameworks. The economic burden of chronic conditions is a key challenge and new and mobile technologies could offer good solutions. mHealth could be considered an evolution of eHealth and could be defined as the practice of medicine and public health supported by mobile communication devices. mHealth approach could overcome limitations linked with the traditional, restricted, and highly expensive in-patient treatment of many chronic pathologies. Possible applications include stepped mHealth approach, where patients can be monitored and treated in their everyday contexts. Unfortunately, many barriers for the spread of mHealth are still present. Due the significant impact of psychosocial factors on disease evolution, psychotherapies have to be included into the chronic disease protocols. Existing psychological theories of health behavior change have to be adapted to the new technological contexts and requirements. In conclusion, clinical psychology and medicine have to face the "chronic care management" challenge in both traditional and mHealth settings

Measurement of microbial activity in soil by colorimetric observation of in situ dye reduction: an approach to detection of extraterrestrial life

BACKGROUND: Detecting microbial life in extraterrestrial locations is a goal of space exploration because of ecological and health concerns about possible contamination of other planets with earthly organisms, and vice versa. Previously we suggested a method for life detection based on the fact that living entities require a continual input of energy accessed through coupled oxidations and reductions (an electron transport chain). We demonstrated using earthly soils that the identification of extracted components of electron transport chains is useful for remote detection of a chemical signature of life. The instrument package developed used supercritical carbon dioxide for soil extraction, followed by chromatography or electrophoresis to separate extracted compounds, with final detection by voltammetry and tandem mass-spectrometry. RESULTS: Here we used Earth-derived soils to develop a related life detection system based on direct observation of a biological redox signature. We measured the ability of soil microbial communities to reduce artificial electron acceptors. Living organisms in pure culture and those naturally found in soil were shown to reduce 2,3-dichlorophenol indophenol (DCIP) and the tetrazolium dye 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT). Uninoculated or sterilized controls did not reduce the dyes. A soil from Antarctica that was determined by chemical signature and DNA analysis to be sterile also did not reduce the dyes. CONCLUSION: Observation of dye reduction, supplemented with extraction and identification of only a few specific signature redox-active biochemicals such as porphyrins or quinones, provides a simplified means to detect a signature of life in the soils of other planets or their moons

Bridging Representation and Visualization in Prosopographic Research: A Case Study

In the last decade, the research on ancient civilizations has started to rely more and more on data science to extract knowledge on ancient societies from the written sources delivered from the past. In this paper, we combine two well-established frameworks: Linked Data to obtain a rich data structure, and Network Science to explore different research questions regarding the structure and the evolution of ancient societies. We propose a multi-disciplinary pipeline where, starting from a semantically annotated prosopographic archive, a research question is translated into a query on the archive and the obtained dataset is the input to the network model. We applied this pipeline to different archives, a Hittite and a Kassite collection of cuneiform tablets. Finally, network visualization is presented as a powerful tool to highlight both the data structure and the social network analysis results

Structure and dynamics of nanoconfined water and aqueous solutions

This review is devoted to discussing recent progress on the structure, thermodynamic, reactivity, and dynamics of water and aqueous systems confined within different types of nanopores, synthetic and biological. Currently, this is a branch of water science that has attracted enormous attention of researchers from different fields interested to extend the understanding of the anomalous properties of bulk water to the nanoscopic domain. From a fundamental perspective, the interactions of water and solutes with a confining surface dramatically modify the liquid's structure and, consequently, both its thermodynamical and dynamical behaviors, breaking the validity of the classical thermodynamic and phenomenological description of the transport properties of aqueous systems. Additionally, man-made nanopores and porous materials have emerged as promising solutions to challenging problems such as water purification, biosensing, nanofluidic logic and gating, and energy storage and conversion, while aquaporin, ion channels, and nuclear pore complex nanopores regulate many biological functions such as the conduction of water, the generation of action potentials, and the storage of genetic material. In this work, the more recent experimental and molecular simulations advances in this exciting and rapidly evolving field will be reported and critically discussed

Immunogenicity Profile of a 3.75-μg Hemagglutinin Pandemic rH5N1 Split Virion AS03A-Adjuvanted Vaccine in Elderly Persons: A Randomized Trial

Background. Elderly persons often experience a reduced immune response to influenza vaccination. We evaluated the usual dose of AS03A-adjuvanted H5N1 pandemic vaccine (3.75 μg hemagglutinin of A/Vietnam/1194/2004-like strain) compared with a double dose in an elderly population