Aflatoxins, a group of highly toxic substances produced by certain species of Aspergillus, especially A. flavus, have been found to occur in agricultural products such as corn, peanuts, cotton seed, animal feed, and many varieties of nuts. Experimental studies show that aflatoxins are carcinogenic. This paper proposes a plan of actions to prevent, control and desinfecting products contaminated with aflatoxins. Post harvest treatment of the product involves drying and storage temperature of 5 °C and relative humidity below 80%. The technique of ozone gas to disinfect contaminated products represents the best alternative because does not generate waste, the product is not damaged and the ozone gas is safe.

We propose algorithms for calculating the diffusion problem in a gas mixture of three components. The algorithms are derived by solving the Maxwell-Stefan equation by Laplace transform. Molar flux are calculated and compared with those obtained from the Taylor-Krishna methodology. The results show that the net diffusion of chemical species in mixtures of more than two components can be set in the opposite direction to the gradient of concentration or may be zero even though the gradient is different from zero

This paper develops a mathematical model to simulate dynamically a reverse osmosis system. The model is formed from materials balances macroscopic unsteady state combined with the model membrane transport: diffusion-solution. In this first part, we solve the system of differential equations assuming a completely mixed flow pattern in the reverse osmosis module (module polarization = 1). The system of equations is solved simultaneously by the Runge-Kutta-Fehlberg method. The results indicate that increasing the area of membrane or pressure increases the volume of recovered product and increasing the initial concentration in the feed reduces the permeate flow severely.

This paper presents an investigation of the extraction of essential oils by steam distillation. The process is analyzed and a model is developed for the extraction of essential oil of eucalyptus in pilot scale with a steam flow of 5.73 g / min. According to the model Dunckhorst-Houghton, which considers the effect of axial dispersion, and the use of optimization procedures to establish the model parameters, excellent agreement was obtained between the amount of oil extracted theoretical and experimental.

This paper develops the analogy between flash distillation and membrane gas separations using a complete mixing module. Methods are provided for calculating the bubble point and the permeate flux as a function of membrane area. Example calculations are presented in the case of gas mixtures: Oxygen-Nitrogen (membrane selectivity = 2.2) and Carbon Dioxide-Methane (membrane selectivity = 31.25). The results show that the selectivity of the membrane has a marked effect on the membrane area required for the separation. Likewise, the permeate flux increases with the area of membrane but the slope of the change is strongly influenced by the selectivity of the membrane. The methods developed in this work can be easily extended to separations or multistage cascade, and for any number of components in the mixture to be separated.

Aflatoxins, a group of highly toxic substances produced by certain species of Aspergillus, especially A. flavus, have been found to occur in agricultural products such as corn, peanuts, cotton seed, animal feed, and many varieties of nuts. Experimental studies show that aflatoxins are carcinogenic. This paper proposes a plan of actions to prevent, control and desinfecting products contaminated with aflatoxins. Post harvest treatment of the product involves drying and storage temperature of 5 °C and relative humidity below 80%. The technique of ozone gas to disinfect contaminated products represents the best alternative because does not generate waste, the product is not damaged and the ozone gas is safe.

We propose algorithms for calculating the diffusion problem in a gas mixture of three components. The algorithms are derived by solving the Maxwell-Stefan equation by Laplace transform. Molar flux are calculated and compared with those obtained from the Taylor-Krishna methodology. The results show that the net diffusion of chemical species in mixtures of more than two components can be set in the opposite direction to the gradient of concentration or may be zero even though the gradient is different from zero

En este trabajo se desarrolla un modelo matemático para simular de forma dinámica un sistema de osmosis inversa. El modelo se conforma a partir de balances macroscópicos de materia en estado no estacionario combinados con el modelo de transporte en la membrana: difusión-solución. En esta primera parte, se resuelve el sistema de ecuaciones diferenciales suponiendo un flujo patrón de mezcla completa en el módulo de osmosis inversa (módulo de polarización=1). El sistema de ecuaciones se resuelve simultáneamente mediante el método de Runge-Kutta-Fehlberg. Los resultados indican que aumentar el área de membrana o de la presión incrementa el volumen de producto recuperado y el incremento de la concentración inicial en la alimentación reduce el caudal severamente.

En este trabajo se presenta una investigación de la extracción de aceites esenciales mediante el arrastre con vapor. Se analiza el proceso y se desarrolla un modelo para la extracción de aceite esencial de eucalipto en escala piloto con un flujo de vapor de 5,73 g / min. Según el modelo de Dunckhorst-Houghton, que considera el efecto de dispersión axial, y el uso de procedimientos de optimización para establecer los parámetros del modelo, se obtuvo una excelente concordancia entre la cantidad extraída de aceite teórico y el experimental.

En este trabajo se desarrolla la analogía entre la destilación flash y las separaciones de gases mediante membranas en un módulo de mezcla completa. Se proporcionan procedimientos de cálculo del punto de burbuja y del flujo de permeado en función del área de membrana. Se presentan ejemplos de cálculo en el caso de mezclas de gases binarias: Oxígeno-Nitrógeno (selectividad de membrana =2.2) y Bióxido de carbono-Metano (selectividad de membrana=31.25). Los resultados muestran que la selectividad de la membrana tiene un marcado efecto en el área de membrana requerido para la separación. Así mismo, el flujo de permeado aumenta con el área de membrana pero la pendiente del cambio es fuertemente influenciado por la selectividad de la membrana. Los procedimientos desarrollados en este trabajo pueden fácilmente extenderse a las separaciones en cascada o de múltiples etapas, y par...

Due lo the importance of conveying the results of university research lo the community, the Vice Rector of Research of San Marcos University is considering taking advantage of such research through the implementation of productive enterprises. To this end we present a business model for technology-based incubators.

Laboratory tests were done to determine the reducing effect of ascorbic acid, citric acid and camu camu (Myrciana dubia). Tests with ascorbic acid and citric acid were made using 2, 3.5 and 7 equivalents of acid to 100 rpm and initial pH of 10. The content of ascorbic and citric acid was determined at 2 and 1.9 grams, respectively, per 100 grams of fresh fruit camu camu. The results indicate that ascorbic acid reduces chromium (Vi) up to 98% in 90 seconds. Citric acid shows no activity.

Debido a la importancia de transmitir los resultados de las investigaciones universitarias a la comunidad, el Vicerrectorado de Investigación de la UNMSM considera la posibilidad de aprovechar tales investigaciones mediante la implementación de empresas productivas. Con este propósito presentamos un modelo de negocios para incubadoras de base tecnológica.

Laboratory tests were done to determine the reducing effect of ascorbic acid, citric acid and camu camu (Myrciana dubia). Tests with ascorbic acid and citric acid were made using 2, 3.5 and 7 equivalents of acid to 100 rpm and initial pH of 10. The content of ascorbic and citric acid was determined at 2 and 1.9 grams, respectively, per 100 grams of fresh fruit camu camu. The results indicate that ascorbic acid reduces chromium (Vi) up to 98% in 90 seconds. Citric acid shows no activity.

The objective of this work is the transformation of fructose to 4-hydroxymethylfurfural by a dehydratation process using the 4-toluenesulfonic acid as catalyst . The reaction was carried out using solutions of fructose in water and fructose in water-acetone (50% volume) in a batch reactor at temperatures of 372 K and 348 K respectively. The yield reached a maximum of 16% to hydroxymethylfurfural, an intermediate for obtaining fuel furan.

The objective of this work is the transformation of fructose to 4-hydroxymethylfurfural by a dehydratation process using the 4-toluenesulfonic acid as catalyst . The reaction was carried out using solutions of fructose in water and fructose in water-acetone (50% volume) in a batch reactor at temperatures of 372 K and 348 K respectively. The yield reached a maximum of 16% to hydroxymethylfurfural, an intermediate for obtaining fuel furan.