New thermal insulation fiberboards from cake generated during biorefinery of sunflower whole plant in a twin-screw extruder

The objective of this study was to manufacture new thermal insulation fiberboards by thermo-pressing. The starting material was a slightly deoiled cake (17.6% oil content), generated during the biorefinery of sunflower (Helianthus annuus L.) whole plant in a co-rotating (Clextral BC 45, France) twin-screw extruder. All fiberboards produced were cohesive mixtures of proteins and lignocellulosic fibers, acting respectively as binder and reinforcing fillers in what could be considered as a natural composite. The molding experiments were conducted using a 400 ton capacity heated hydraulic press (Pinette Emidecau Industries, France). The influence of molding conditions on board density, mechanical properties and heat insulation properties was examined. Molding conditions included mold temperature (140-200°C), pressure applied (150-250 kgf/cm²) and molding time (40-76 s), and these greatly affected board density and thus the mechanical and heat insulation properties. Board density increased with increasingly extreme molding conditions, rising from 500 to 858 kg/m³. The mechanical properties increased at the same time (from 52 to 660 kPa for flexural strength at break, from 5.9 to 49.4 MPa for elastic modulus, from 0.5 to 7.7 kJ/m² for Charpy impact strength, and from 19.2 to 47.1° for Shore D surface hardness). Conversely, heat insulation properties improved with decreasing board density, and the lowest thermal conductivity (88.5 mW/m K at 25°C) was obtained with the least dense fiberboard. The latter was produced with a 140°C mold temperature, a 150 kgf/cm² pressure applied and a 40 s molding time. A medium mold temperature (160°C) was needed to obtain a good compromise between mechanical properties (272 kPa for flexural strength at break, 26.3 MPa for elastic modulus, 3.2 kJ/m² for Charpy impact strength, and 37.3° for Shore D surface hardness), and heat insulation properties (99.5 mW/m K for thermal conductivity).The corresponding board density was medium (687 kg/m³). Because of their promising heat insulation properties, these new fiberboards could be positioned on walls and ceilings for thermal insulation of buildings. The bulk cake also revealed very low thermal conductivity properties (only 65.6 mW/m K at 25°C) due to its very low bulk density (204 kg/m³). It could be used as loose fill in the attics of houses

Análisis termofísico de materiales vegetales e industrializados aplicados a techumbres, como recurso bioclimático en el pacífico sur del estado de Oaxaca

160 páginas. Maestría en Diseño.Con la finalidad de analizar las propiedades de conductividad termofísica de materiales vegetales e industrializados compuestos, así como de componentes constructivos para analizar las posibilidades de reducir las ganancias de calor en las techumbres de un clima cálido semihúmedo, de la zona costa del estado de Oaxaca, se hicieron pruebas de conductividad térmica en muestras pequeñas utilizado el Conductivimetro del CENIDET (aparato de guarda) para compararlos con aquellos del mismo material, pero que forman parte de componentes constructivos para tal efecto se prepararon muestras de materiales, para comparar las propiedades térmicas medidas con los valores de una losa de concreto convencional a tamaño real. Las mediciones de conductiviad para estas muestras se llevaron a cabo con un Conductivimetro construido para este propósito en la UAM-A por el autor. De esta manera se realizó la comparación entre los valores de conductividad térmica de muestras pequeñas que fueron medidas utilizado el Conductivimetro del CENIDET, contra los valores obtenidos de componentes constructivos utilizando el Conductivimetro de la UAM-A

Within-host population dynamics of antibiotic-resistant M. tuberculosis

Mathematical models for the population dynamics of de novo resistant Mycobacterium tuberculosis within individuals are studied. The models address the use of one or two antimicrobial drugs for treating latent tuberculosis (TB). They consider the effect of varying individual immune response strength on the dynamics for the appearance of resistant bacteria. From the analysis of the models, equilibria and local stabilities are determined. For assessing temporal dynamics and global stability for sensitive and drug-resistant bacteria, numerical simulations are used. Results indicate that for a low bacteria load that is characteristic of latent TB and for small reduction in an immune response, the use of a single drug is capable of curing the infection before the appearance of drug resistance. However, for severe immune deficiency, the use of two drugs will provide a larger time period before the emergence of resistance. Therefore, in this case, two-drugs treatment will be more efficient in controlling the infection

Entorno del Turismo Turismo y Gastronomía: sociedad y humanismo

Bajo la convocatoria del VI Seminario Internacional de Estudios Turísticos, el VIII Foro de Investigación Turística y el III Seminario Internacional de Investigación en Gastronomía, en noviembre de 2010 se dieron cita 90 investigadores nacionales e internacionales con la finalidad de compartir sus resultados de investigación y, al mismo tiempo, calibrar posibilidades y limitaciones en las estrategias teórico-metodológicas para la construcción de objetos de estudio del turismo en sus dimensiones educativas, ambientales, gastronómicas y socioculturales, que permitieran una nueva concepción del turismo en su carácter científico y a la vez la detección de metodologías adecuadas a las necesidades del posgrado de la institución