RESUMO
The determination of an average value for the surface energy of talc (gammaS) via solid-water interfacial interactions is described. It is based on a formula obtained by the combination of the Young equation with a general equation of pair interaction. Important features of the method are (a) the use of the Young equation to determine the range where the value of the surface energy lies and (b) the determination of the mean value within this range using a probability function. The value found is 217.31 mJ m(-2) in the range 193.36-257.43 mJ m(-2).
Assuntos
Talco/química , Água , Adsorção , Propriedades de Superfície , TermodinâmicaRESUMO
By combining the relation that describes pair interaction in binary mixtures with the Young equation, a formula is obtained for calculating the surface energy of montmorillonite as a function of the surface pressure, the surface tension of water, and the liquid/solid contact angle. The formula is an equation of an inverted parabola, which could be represented by a polynomial function. Roots of the polynomial gave one real value of 205.066+/-2.764 mJm(-2) for the surface energy of montmorillonite. The value obtained is of the expected magnitude and probably is better than those obtained by previous approaches.
RESUMO
The effect of particle concentration, in kaolin suspensions, on the adsorption of 2,2'-bipyridyl was studied. Adsorption expressed in units of micromoles per gram decreased as a result of the increase in particle concentration and also as a result of the presence of coagulant (0.25 M NaCl). Dispersion treatment with sodium hexametaphosphate increased the adsorption of bipyridyl. The decrease in adsorption with the increase in particle concentration suggests a possible relation between adsorption and flocculation phenomena. On the basis of classic flocculation theory a straight-line relation was obtained between the square root of the adsorption maximum (mmol/L) and particle concentration (g/L). It is concluded that particle association, which is a function of particle concentration, reduces the surface/aqueous interface and consequently the adsorption of bipyridyl. Copyright 2000 Academic Press.
Assuntos
Hepatite C/complicações , Falência Renal Crônica/complicações , Transplante de Rim , Hepatopatias/complicações , Seleção de Pacientes , Obtenção de Tecidos e Órgãos/organização & administração , Listas de Espera , Argentina/epidemiologia , Hepatite C/epidemiologia , Humanos , Falência Renal Crônica/terapia , Hepatopatias/epidemiologia , Prevalência , Diálise RenalAssuntos
Pneumotórax/complicações , Síndrome do Desconforto Respiratório do Recém-Nascido/etiologia , Corticosteroides/uso terapêutico , Diagnóstico Diferencial , Feminino , Humanos , Recém-Nascido , Masculino , Enfisema Mediastínico/diagnóstico , Oxigenoterapia , Respiração Artificial/efeitos adversosRESUMO
El neumotorax y el neumomediastino deben tenerse presente en la etiologia del SDR del recien nacido. Se ha insistido en que la introduccion de procedimientos de ventilacion asistida ha aumentado su riesgo e incidencia. Se analizan 12 casos clinicos de neumotorax sintomatico pesquisados en el Servicio de Neonatologia del Hospital Paula Jaraquemada en el lapso de 2 anos.En el analisis destaca la falta de antecedentes predisponentes definidos. En 7 casos se efectuo toracotomia minima. Se observo una sobrevida a la semana de vida de 8 casos (66%). Se comenta el manejo actual del neumotorax, a fin de mejorar sus expectativas de vida