Synthesis of Dioxigenated Systems. Preparation of Homologues of 1,4-Benzodioxin as Calcium Antagonists

A new compound (9), homologue of 1,4-benzodioxin, has been prepared and tested as calcium antagonist. Additionally, the intermediates 12 and 13 with structure of aminodiol, were also evaluated as anticalcium agents. All of them showed a moderate anticalcium activity

Thermal analysis of droplet flow: Numerical, analytical and experimental investigations

This article reports the thermal behavior analysis of droplet flow for a scenario in which the hydrodynamic and thermal effects are coupled in a cylindrical miniaturized channel; this analysis was performed by comparing numerical, analytical and experimental results. The 3D numerical modeling of the droplet flow was performed using THETIS, a multi-fluid Navier–Stokes solver. A 1D analytical model in Lagrangian space based on a thin-fin thermal approximation was developed. Infrared thermography measurements of droplet flows were used to experimentally determine the temperature fields inside droplets, and these results were compared with those obtained from the simulations and the analytical approach. The originality of this work is the choice of a particular thermal scene to mimic a chemical situation in order to improve understanding and to illustrate the predominant exchanges by model simplification. Furthermore, the results of this study are important for understanding the heat transfer occurring inside droplets for lab-on-chip applications

Weightless experiments to probe universality of fluid critical behavior

Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μK) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena

Boiling crisis dynamics: low gravity experiments at high pressure

To understand the boiling crisis mechanism, one can take advantage of the slowing down of boiling at high pressures, in the close vicinity of the liquid-vapor critical point of the given fluid. To preserve conventional bubble geometry, such experiments need to be carried out in low gravity. We report here two kinds of saturated boiling experiments. First we discuss the spatial experiments with SF 6 at 46 ∘C. Next we address two ground-based experiments under magnetic gravity compensation with H 2 at 33 K. We compare both kinds of experiments and show their complementarity. The dry spots under vapor bubbles are visualized by using transparent heaters made with metal oxide films. We evidence two regimes of the dry spots growth: the regime of circular dry spots and the regime of chain coalescence of dry spots that immediately precedes the heater dryout. A recent H 2 experiment is shown to bridge the gap between the near-critical and low pressure boiling experiments

Crossover equation of state models applied to the critical behavior of Xenon

The turbidity ( τ ) measurements of Güttinger and Cannell (Phys Rev A 24:3188–3201, 1981) in the temperature range 28mK≤T−Tc≤29K along the critical isochore of homogeneous xenon are reanalyzed. The singular behaviors of the isothermal compressibility ( κT ) and the correlation length ( ξ ) predicted from the master crossover functions are introduced in the turbidity functional form derived by Puglielli and Ford (Phys Rev Lett 25:143–146, 1970). We show that the turbidity data are thus well represented by the Ornstein–Zernike approximant, within 1 % precision. We also introduce a new crossover master model (CMM) of the parametric equation of state for a simple fluid system with no adjustable parameter. The CMM model and the phenomenological crossover parametric model are compared with the turbidity data and the coexisting liquid–gas density difference ( ΔρLV ). The excellent agreement observed for τ , κT , ξ , and ΔρLV in a finite temperature range well beyond the Ising-like preasymptotic domain confirms that the Ising-like critical crossover behavior of xenon can be described in conformity with the universal features estimated by the renormalization-group methods. Only 4 critical coordinates of the vapor–liquid critical point are needed in the (pressure, temperature, molecular volume) phase surface of xenon