Experimental study of linear and nonlinear regimes of density-driven instabilities induced by CO2 dissolution in water

Density driven instabilities produced by CO2 (gas) dissolution in water containing a color indicator were studied in a Hele Shaw cell. The images were analyzed and instability patterns were characterized by mixing zone temporal evolution, dispersion curves, and the growth rate for different CO2 pressures and different color indicator concentrations. The results obtained from an exhaustive analysis of experimental data show that this system has a different behaviour in the linear regime of the instabilities (when the growth rate has a linear dependence with time), from the nonlinear regime at longer times. At short times using a color indicator to see the evolution of the pattern, the images show that the effects of both the color indicator and CO2 pressure are of the same order of magnitude: The growth rates are similar and the wave numbers are in the same range (0?30 cm-1) when the system is unstable. Although in the linear regime the dynamics is affected similarly by the presence of the indicator and CO2 pressure, in the nonlinear regime, the influence of the latter is clearly more pronounced than the effects of the color indicator.Fil: Outeda, Mabel Noemi. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: El Hasi, Claudio Daniel. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: D'onofrio, Alejandro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Zalts, Anita. Universidad Nacional de General Sarmiento. Instituto de Ciencias. Área de Química; Argentin

Differential diffusion effects on buoyancy-driven instabilities of acid-base fronts: The case of a color indicator

Buoyancy-driven hydrodynamic instabilities of acid-base fronts are studied both experimentally and theoretically in the case where an aqueous solution of a strong acid is put above a denser aqueous solution of a color indicator in the gravity field. The neutralization reaction between the acid and the color indicator as well as their differential diffusion modifies the initially stable density profile in the system and can trigger convective motions both above and below the initial contact line. The type of patterns observed as well as their wavelength and the speed of the reaction front are shown to depend on the value of the initial concentrations of the acid and of the color indicator and on their ratio. A reaction-diffusion model based on charge balances and ion pair mobility explains how the instability scenarios change when the concentration of the reactants are varied.Fil: Kuster, S.. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Riolfo, L. A.. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Zalts, Anita. Universidad Nacional de General Sarmiento; ArgentinaFil: El Hasi, C.. Universidad Nacional de General Sarmiento; ArgentinaFil: Almarcha, C.. Université Libre de Bruxelles; BélgicaFil: Trevelyan, P.M.J.. Université Libre de Bruxelles; BélgicaFil: De Wit, A.. Université Libre de Bruxelles; BélgicaFil: D'onofrio, Alejandro Gustavo. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Conductas preventivas frente a traumatismos dentales : Etapa 4

Los traumatismos alveolodentales son lesiones causadas por fuerzas que actúan sobre el órgano dentario y los tejidos de sostén siendo diagnosticados a simple vista o radiográficamente. Estas afecciones se dan fundamentalmente en los niños y adolescentes, e incluyen la pérdida de piezas dentarias temporales y permanentes. Provocan además una disfunción que altera, de manera conjunta, la psicología del niño, la fonética, la masticación y la estética. Son considerados como una urgencia dentro de la asistencia odontológica y deben ser diagnosticados y tratados de forma certera e inmediata por el odontólogo.Facultad de Odontologí

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements