Dynamics of simulated water under pressure

We present molecular dynamics simulations of the SPC/E model of water to probe the dynamic properties at temperatures from 350 K down to 190 K and pressures from 2.5GPa (25kbar) down to -300MPa (-3kbar). We compare our results with those obtained experimentally, both of which show a diffusivity maximum as a function of pressure. We find that our simulation results are consistent with the predictions of the mode-coupling theory (MCT) for the dynamics of weakly supercooled liquids -- strongly supporting the hypothesis that the apparent divergences of {\it dynamic} properties observed experimentally may be independent of a possible thermodynamic singularity at low temperature. The dramatic change in water's dynamic and structural properties as a function of pressure allows us to confirm the predictions of MCT over a much broader range of the von Schweidler exponent values than has been studied for simple atomic liquids. We also show how structural changes are reflected in the wave-vector dependence of dynamic properties of the liquid along a path of nearly constant diffusivity. For temperatures below the crossover temperature of MCT (where the predictions of MCT are expected to fail), we find tentative evidence for a crossover of the temperature dependence of the diffusivity from power-law to Arrhenius behavior, with an activation energy typical of a strong liquid.Comment: 14 pages, 15 figure

Supercooled Water: Dynamics, Structure and Thermodynamics

The anomalous properties of water in the supercooled state are numerous and well-known. Particularly striking are the strong changes in dynamic properties that appear to display divergences at temperatures close to -- but beyond -- the lowest temperatures attainable either experimentally or in computer simulations. Recent work on slow or glassy dynamics in water suggests analogies with simple liquids not previously appreciated, and at the same time highlights some aspects that remain peculiar to water. A comparison of the behavior of water with normal liquids, with respect to its dynamic, thermodynamic and structural changes in the supercooled regime is made by analyzing, via computer simulations, the properties of local potential energy minima sampled by water in supercooled temperatures and pressures.Comment: Submitted to DAE(India) Solid State Physics Symposium. 4 pages, Revtex (two column), 6 figures (eps

The Influence of Type of Implicit EWOM on Purchase Intention

Electronic Word-of-mouth (eWOM) helps shape consumers’ purchasing decisions and companies’ marketing choices. Researchers and practitioners have extensively studied textual or word-based eWOM in online reviews, blogs, e-mails, and product sites. The effect of implicit eWOM, eWOM using paralinguistic cues, on consumer behavior has been infrequently studied even though marketers often seek to use implicit eWOM to influence consumers. On Facebook, the most popular social networking platform in the world, three of the most frequently used forms of implicit eWOM are the emoticon, the emoji, and the GIF. A comparison of the effect of types of implicit eWOM on the purchase intention of eWOM receivers was made in two studies. Four theories, specifically, (Social Presence Theory, Short et al., 1976), Affect as Information Theory, (Clore & Storbeck, 2006), the Elaboration Likelihood Model (Petty & Cacioppo, 1984) and the Foote, Cone, and Belding Grid Model (Vaughn, 1980, 1986), were used to frame the studies. In Study 1, four independent groups were shown product reviews that were text only, text plus emoticon, text plus emoji, or text plus GIF. Half of each group were shown a product review of candy and half were shown a product review of a computer. The products represent different levels of engagement and cognitive/affective processing. Study 2 included four independent groups shown product reviews that were text only or text followed by either an emoticon, an emoji, or a GIF. Each participant was shown reviews of three products (candy, a chair, or a computer), chosen to represent different levels of engagement and cognitive/affective processing. All pairs of groups were compared using an independent groups t-test. No significant increase in purchase intention due to implicit eWOM was found in either study. In two comparisons between text only and 1) text plus emoticon and 2) text plus emoji, purchase intention was higher for the text only review than for the review that included a paralinguistic cue

Radiation-Curable Adhesives for Wood Composites

Wood composites are widely used in construction applications because of their superior dimensional and structural attributes over raw wood products. However, current wood composite manufacturing practices, which rely on thermal-curing of adhesives, are expensive, energy intensive, time consuming and are prone to manufacturing defects. Use of radiation curable adhesives (RCAs) could potentially answer all of these issues. Specifically, use of electron-beam (e-beam) radiation has been increasing in areas of research and industry where rapid, low-temperature polymerization is required and low energy consumption is desired. For e-beams to be used in wood composites, however, it must be determined whether or not the wood is structurally impacted by irradiation, and to what extent. Maple beams irradiated with a range of e-beam dosages were studied in three-point bend tests to assess the changes in bulk properties of the wood, and were further studied with infrared spectroscopy to identify chemical changes resulting from the radiation treatments. Also, dynamic mechanical analysis (DMA) was performed on maple veneers treated with the same doses of radiation to characterize changes in the viscoelastic properties. Furthermore, while RCAs and their curing have been studied, it is important to understand if the presence of wood will impede the polymerization of these adhesives, and to what extent. Maple veneers impregnated with one of two resins were cured with the same e-beam dosages and investigated by means of DMA and FTIR spectroscopy. Swelling tests were conducted to detect interaction between the resins and the wood, which would indicate good interfacial bonding in the composite matrix. Notable loss of strength was observed in the irradiated wood, especially at 180kGy. Monitoring the glass transition temperature (Tg) and activation energy (Ea) derived from DMA revealed that the most destructive trends in the wood began around 80kGy. Cure of resins in the composites was hindered by the presence of the wood, but both resins did eventually reach complete cure at doses higher than what the neat resins required. Interaction between the resins and the wood was evident. In the end, results indicate that there is a range of radiation dosages in which the resin in a wood composite can be cured without destroying the structural integrity of the wood