BACKGROUND: Poly(3-hydroxybutyrate) (P3HB) is a biopolymer of bacterial origin widely studied for its physicochemical characteristics, biocompatibility, nontoxicity and biodegradability. Unfortunately, there is no extraction and purification process that allows sustainable large-scale production of the biopolymer. RESULTS:The solubility of P3HB in several non-halogenated solvents was studied to achieve a novel and environmentally friendly methodology for polymer solvent extraction from bacterial cells. Acetic acid, ethyl acetate, butyl acetate and methyl ethyl ketone were selected using theoretical approximations for the experimental evaluation of solubility at various temperatures, concentrations and incubation times with a complete general factorial experimental design. The results were interpreted with analysis of variance to evaluate the influence of each factor on the solubility. It was determined that at temperatures above 90°C, acetic acid has a high P3HB solubilization efficiency, which makes it an excellent candidate for an environmentally friendly solvent-extraction process. The mass yield of the extraction process with the new procedure was 54.8% compared to 59.9% for the standard chloroform solvent-extraction process. Also, thermogravimetric analysis and differential scanning calorimetry showed thermal behavior to be similar between P3HB recovered using chloroform and acetic acid extraction.CONCLUSIONS: P3HB extraction from Burkholderia cepacia cells using acetic acid extraction and methanol purification is a promising method for large-scale biopolymer production due to the elimination of hazardous solvents from the process. However, polymer purity and yield are slightly affected compared to the conventional chloroform extraction process.

Las redes tradicionales están diseñadas e implementadas con diferentes dispositivos de red, como routers, switches y firewalls; cada uno tiene unas funciones asociadas y es configurado con diferentes estándares y protocolos para realizar la trasmisión de paquetes. Pero este modelo tradicional no es el único que existe, hoy en día se está empezando a imponer un nuevo modelo de red definida por software [SDN por Software Define Networks]. Si bien este modelo usa los mismos dispositivos de red, es diferente pues utiliza las ventajas del software de programación, el cual mediante una inter- faz universal controla los dispositivos de red y programa los servicios de envío o enrutamiento de paquetes. Este artículo presenta las ventajas de las SDN respecto de las redes tradicionales y muestra pruebas de desempeño básicas realizadas en un ambiente de laboratorio con una tarjeta NetFPGA implementando OpenFlow, en contraste con pruebas de desempeño realizadas con dispositivos de red comerciales.

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Since the first developments around spray drying in 1870, multiple contributions have been made to obtain design parameters that have led to heuristics. However, experimental studies are required to design and build spray drying equipment for specific applications. From the heuristics reported in books, catalogues and patents, the dimensions and operating conditions have been selected to execute the mathematical modeling of a spray dryer with different models, starting from a relatively simple model of single-phase incompressible flow, to a more complex model that contemplates multiphase flow. This study shows the preliminary results obtained for the simulation of a cocurrent spray drying system using the CFD software OpenFoam.

This article presents the design, implementation and use of a remote network lab with multiple users support as an aid to teaching computer networks. The purpose is to enable multiple students complement their theoretical learning with practical experimentation in networking devices which can be carried out synchronously to theoretical classes and from any room with internet access. Unlike the current solutions based on mainly software emulation and simulation, the students interact remotely with commercial network devices, such as cutting-edge and widely used switches, routers and firewalls at the workplace. This proposal reduces the expenses or installing new laboratories in all the campuses where lectures are held and also moving the students to laboratories that are not located near their classrooms. The use of the remote laboratory has been tested with senior students majoring information technology engineering. The results shows that a remote network lab is an effective aid for teaching computer networks in a remote and secure way.