Heat flow in the postquasistatic approximation

We apply the postquasistatic approximation to study the evolution of spherically symmetric fluid distributions undergoing dissipation in the form of radial heat flow. For a model which corresponds to an incompressible fluid departing from the static equilibrium, it is not possible to go far from the initial state after the emission of a small amount of energy. Initially collapsing distributions of matter are not permitted. Emission of energy can be considered as a mechanism to avoid the collapse. If the distribution collapses initially and emits one hundredth of the initial mass only the outermost layers evolve. For a model which corresponds to a highly compressed Fermi gas, only the outermost shell can evolve with a shorter hydrodynamic time scale.Comment: 5 pages, 5 figure

Optimisation of heterogeneous batch extractive distillation

This paper considers the optimisation of batch extractive distillation, using heterogeneous entrainers for the first time. The objective function includes the maximum of overall profit and the optimisation variables are the entrainer flowrate and the reflux ratio that is an optimal combination of both decanted phases. Simulation and optimization is performed within MATLAB, by using a genetic algorithm coupled to a short-cut model of the distillation column. The performance of the optimisation scheme is illustrated through the separation of chloroform – methanol mixture with water considering either a constant or a piecewise constant policy for both optimization variables

Heterogeneous batch distillation processes for waste solvent recovery in pharmaceutical industry

A summary about our experiences in the introduction of heterogeneous entrainers in azeotropic and extractive batch distillation is presented in this work. Essential advantages of the application of heterogeneous entrainers are showed by rigorous simulation and experimental verification in a bench batch distillation column for separating several azeotropic mixtures such as acetonitrile – water, n hexane – ethyl acetate and chloroform – methanol, commonly found in pharmaceutical industry

In vitro Behavior of Enterotoxigenic Escherichia coli in Increasing Copper Concentrations.

Cupric sulfate is widely used as growth promoter for swine productions, in spite of its ecological risks. The aim of this paper was to study the in vitro behavior of Enterotoxigenic Escherichia coli in increasing concentrations of copper. To achieve that, two reference strains: A-1 (O149: K91: K88ac) and E68-I (O141: K85: K88ab), were used with other four strains isolated from herds with colibacillosis. The reference strains were grown in Mueller-Hinton agar, according to the concentration gradient technique with weekly increasing values, from 5 to 50 mg/mL of CuSO4. The experiment lasted three weeks. Though in the initial contacts two wild strains were the best adapted, at the end all developed high tolerance to the metal. For A-1, it may be determined by the formation of biofilm, which, apart from the said resistance, is an important factor of virulence in infectious bacterial processes. The results observed are another element to add to the dangers of using these salts as growth promoters in swine productions

Enterotoxigenic Escherichia coli Antibio-Resistance Induced by Copper.

Cupric sulfate is widely used as growth promoter for swine productions, in spite of its ecological risks. The purpose of this paper was to evaluate the in vitro effect of copper as inducer of antibio-resistance in Enterotoxigenic. E. coli. A-1 (O149: K91: K88ac) and E68-I (O141: K85: K88ab) reference strains were grown in Mueller-Hinto agar, according to the concentration gradient technique with weekly increasing values, from 5 to 50 mg/mL of CuSO 4. Both bacteria were cultured for three weeks; the controls were cultured parallely, in the same medium, without the inducer. Then, antibiograms were made to evaluate sensitivity against gentamicin, kanamycin, tetracycline, chloramphenicol, carbenicilin, and nalidixic acid. The results from the strains challenged with salt showed halos compatible to resistant phenotypes, in contrast to the controls (all sensitive). The results evidence the capacity of copper to induce in vitro bacterial antibio-resistance, which must be considered by producers when copper salts are used as growth promoters. In addition to ecological damages, antimicrobials lose effectiveness in human and animal therapeutics

Análisis de una muestra de concreto de 4000 psi sintetizada a partir de suelo diatomáceo con activación alcalina

Trabajo de investigaciónSe ha querido investigar a partir de la composición química de la Diatomea, el reemplazo en un 100% del CP evaluando sus propiedades mecánicas. Se investigó acerca de los materiales químicamente. Se analizó la composición química tanto del CP como el de la Diatomea y a partir de esto se realizó un diseño de la composición química de la diatomea similar a la del CP. Se realizaron en total 15 muestras para ser ensayadas en el laboratorio donde se realizaron los ensayos de flexión y compresión de muestras de Concreto según normatividad INV 410-13 y 415-13 y así mismo para mortero se realizaron ensayos de Compresión según normatividad NTC 220.RESUMEN GLOSARIO 1. INTRODUCCIÓN 2. ANTECEDENTES Y JUSTIFICACIÓN 3. PLANTEAMIENTO Y FORMULACIÓN DEL PROBLEMA 4. OBJETIVOS 5. ALCANCES Y LIMITACIONES 6. ESTADO DEL ARTE. 7. MARCO TEÓRICO 8. MARCO LEGAL 9. METODOLOGÍA 10. DESARROLLO DE LA INVESTIGACIÓN 11. RESULTADOS Y ANÁLISIS 12. CONCLUSIONESPregradoIngeniero Civi

Clasificación y estimación de los riesgos naturales: Isla de La Palma.

La isla de La Palma se encuentra en el extremo más noroccidental de las Islas Canarias, tiene una superficie de unos 708 kilómetros cuadrados y una población que supera los 80.000 habitantes. En este trabajo se pretende analizar los riesgos más importantes haciendo una mención especial a los sucedidos en los últimos años. Un buen número de víctimas mortales y cuantiosas pérdidas económicas en bienes materiales y recursos medioambientales han sido las consecuencias causadas por la acción de Lluvias Intensas, Incendios forestales y olas de calor, entre otros riesgos. Hemos estimado y clasificado estos riesgos a las que está expuesta la isla de La Palma mostrando además algunos umbrales máximos esperados en cada uno de los fenómenos clasificados.The island of La Palma is located in the northwestern tip of the Canary Islands; it has an area of about 708 square kilometers and a population of over 80,000 habitants. This paper aims to analyze the most important risks making a special mention of those that occurred in recent years. A good number of deathly victims and economic losses in property and environmental resources have been the consequences caused by the action of Heavy Rain, forest fires and heat waves, between other risks. We have estimated and classified these risks to which is exposed the island of La Palma also showing some expected maximum thresholds in each of the phenomena classified