Valoración de la fracción hemicelulósica y obtención de furfural a partir de Eucalyptus globulus y paja de trigo

El objetivo de este estudio fue optimizar la producción de furfural mediante procesos de hidrólisis (autohidrólisis isotérmica y no isotérmica, hidrólisis ácida con extracción alcalina y ácida diluida) de madera de Eucalyptus globulus y paja de trigo, utilizando un diseño experimental factorial y modelos de regresión múltiple para Maximizar los rendimientos de furfural. Optimización de la concentración de furfural a partir de Eucalyptus globulus y Paja de Trigo mediante autohidrólisis No isoterma. Las muestras de Paja de Trigo y Eucalyptus globulus fueron sometidas a autohidrólisis no isotérmica, definida por: temperatura: 180-240ºC. En esa forma, se pudo encontrar a una temperatura de 220 ° C, 4,25 g / 100 g de materia prima (26% del xilano inicial en la paja de trigo) y un aumento de temperatura (240ºC) produjo 4,54 g / 100 g de materia prima, 28% del xilano inicial. En Eucalyptus globulus el aumento de la temperatura de hidrólisis (240ºC) produjo un licor con mayores contenidos de furfural (4,45 g / 100 g de materia prima, 25% del xilano inicial) y ácido acético (4,49 g / 100 g de materia prima) y contenidos pequeños de arabinosa y xilano. Procesos de autohidrólisis isotérmica para la producción de furfural a partir de Eucalyptus globulus y paja de trigo Para los procesos de autohidrólisis isotérmica, las muestras de Eucalyptus globulus fueron sometidas a temperaturas comprendidas entre 220 y 250 ºC y tiempos de residencia isotérmica entre 0 y 60 min. Se ha estudiado el efecto del factor R0 sobre la producción de azúcar y la composición de las fases líquida y sólida obtenidas después de los tratamientos. Se utilizó un diseño experimental compuesto central, junto con el modelo de redes neuronales, para la maximización del contenido de furfural bajo autohidrólisis isotérmica. En condiciones experimentales óptimas, se obtuvo el rendimiento de furfural (4,4 g / 100 g de materia prima seca) a 60 min ya 220 ºC. Para la paja de trigo, las muestras fueron sometidas a autohidrólisis isotérmica en las mismas condiciones de temperatura y tiempo de residencia que la madera de Eucalyptus globulus. En la paja de trigo, el aumento de la temperatura de hidrólisis produjo licor con mayores contenidos de furfural y bajo contenido de xilano. Procesos de hidrólisis ácida para la producción de furfural de Eucalyptus globulus y paja de trigo Para optimizar la producción de furfural por hidrólisis con ácido diluido de madera de Eucalyptus globulus, se utilizaron dos etapas de hidrólisis. El proceso de optimización se llevó a cabo utilizando un diseño experimental factorial y modelos de regresión múltiple para maximizar los rendimientos de furfural. Los rangos operacionales son especialmente adecuados para la extracción de xilosa, que era prácticamente cuantitativa a 170 ºC y prácticamente independiente del tiempo de operación. La concentración de ácido es la variable más influyente en la conversión de xilooligómeros o xilosa en furfural. Las conversiones a furfural fueron bastante importantes (mayores de 10 g / L). Las hemicelulosas en la materia prima se extrajeron en 32-57,7% y xilano en 40,5-84%. Las conversiones más altas a furfural se obtuvieron usando un tiempo de operación medio (15 min) y baja temperatura (170 ºC) y pH = 2. La revisión de la información bibliográfica sobre la extracción de hemicelulosas de la paja de trigo indican que es un material adecuado. pero la transformación a furfural ha sido muy poco eficaz en el rango de condiciones operacionales ensayadas. Procesos de extracción alcalina en frío para la producción de furfural de Eucalyptus globulus y paja de trigo En esta sección se propone un método para la extracción selectiva de hemicelulosa a partir de paja de trigo que implica extracción alcalina en frío y posterior separación por precipitación con etanol. Estas hemicelulosas, obtenidas selectivamente, podrían utilizarse para su conversión en furfural. El rendimiento de hemicelulosa se optimizó utilizando un diseño de factor 2n para examinar la influencia de temperaturas de 20 a 40 ºC, tiempos de operación de 30 a 60 min y concentraciones de álcali de 80 a 120 g / L. Las condiciones óptimas para la extracción alcalina en frıo de hemicelulosa a partir de paja de trigo se encontraron por tanto a una temperatura de 40 ◦ C, un tiempo de funcionamiento de 90 min y una concentración de álcali de 100 g / l. Sin embargo, en el estudio de los resultados obtenidos de la extracción alcalina en frío de hemicelulosas de madera de Eucalyptus globulus a baja temperatura se encuentran bajas concentraciones de glucosa y hemicelulosas .La conclusión general es que la madera de Eucalyptus globulus es mucho más refractaria a este proceso de extracción que otros materiales.The aim of this study was to optimize the production of furfural by some hydrolysis processes (isothermal and non isothermalauthodydrolysis, acid hydrolysis with dilute acid and cold alkaline extraction) of Eucalyptus globulus wood and wheat straw, using factorial experimental design and multiple regression models to maximize furfural yields. Non isothermal autohydrolysis processes for furfural production from Eucalyptus globulus and wheat straw In the first part, samples of Wheat Straw and Eucalyptus globulus were subjected to non-isothermal autohydrolysis, defined by: temperature: 180-240ºC In that form, 4.25 g/100 g raw material (26% of the initial xylan in wheat straw) could be found at 220ºC, and an increase temperature (240ºC) yielded 4.54 g/100 g raw material, 28% of the initial xylan. In Eucalyptus globulus the increase in the hydrolysis temperature (240ºC) yielded liquor with higher contents of furfural (4.45 g/100 g raw material, 25% of the initial xylan) and acetic acid (4.49 g/100 g raw material) and smaller contents of arabinose and xylan. Isothermal autohydrolysis processes for furfural production from Eucalyptus globulus and wheat straw For isothermal autohydrolysis processes, samples of Eucalyptus globulus where subjected to temperature ranges between 220 and 250 ºC and isothermal residence times between 0 and 60 min. The effect of the R0 factor on the sugar yield and composition of both liquid and solid phases obtained after treatments has been studied. A central composite experimental design, in conjunction with the neural fuzzy model, was used to the furfural content maximization under isothermal autohydrolysis. Under optimum experimental conditions, the yield of furfural (4.4 g/100 g dry raw material) could be obtained at 60 min and 220 ºC. For wheat straw, samples of raw material were subjected to isothermal autohydrolysis at same conditions of temperature and residence time that Eucalyptus globulus wood.. In that form, in wheat straw, the increase in the hydrolysis temperature yielded liquor with higher contents of furfural and low xylan contents. Acid hydrolysis processes for furfural production from Eucalyptus globulus and wheat straw To optimize the production of furfural by hydrolysis with dilute acid of Eucalyptus globulus wood, two stages of hydrolysis were used. The optimization process was carried out using a factorial experimental design and multiple regression models to maximize furfural yieldsThe operational ranges are especially suitable for the extraction of xylose, which was virtually quantitative at 170 ºC and virtually independent of the operation time. This is quite important if one considers the low acid concentration used. Conversions to furfural were quite substantial (greater than 10 g/L). Hemicelluloses in the raw material were extracted by 32–57.7% and xylan by 40.5–84%. The highest conversions to furfural were obtained by using a medium operation time (15 min) and low temperature (170 ºC) and pH=2. The review of bibliographic information on the extraction of hemicelluloses from wheat straw seemed to indicate that it might be of a suitable material. In fact, the rates of extraction of hemicelluloses have been acceptable, but the transformation to furfural has been very little effective in the range of operational conditions tested. Cold alkaline extraction processes for furfural production from Eucalyptus globulus and wheat straw In this section, a method for the selective extraction of hemicellulose from wheat straw involving cold alkaline extraction and subsequent separation by precipitation with ethanol is proposed. These hemicelluloses, selectively obtained could be used for their conversion to furfural. The hemicellulose yield was optimized by using a 2n factor design to examine the influence of temperatures from 20 to 40 °C, operation times from 30 to 60 min and alkali concentrations from 80 to 120 g/L. The optimum conditions for cold alkaline extraction of hemicellulose from wheat straw were thus found to be a temperature of 40 °C, an operation time of 90 min and an alkali concentration of 100 g/L. However, in the study of the results obtained from the cold alkaline extraction of hemicelluloses of Eucalyptus globulus wood to low temperature are low concentrations of glucose, xylose, and arabinose in retrieved liquor. The general conclusion is that the wood of Eucalyptus globulus is much more refractory to this extraction process than other materials in the range of variation of the operational conditions tested

El turismo senior como segmento de mercado emergente

This paper will focus on senior tourism, which has not been still very important in tourism market. By the moment literature is very poor about this new form of tourism and reveals a lack of conceptual consensus, so it is needed to clarify this term. It is also necessary to study in depth motivations, behavior, and information sources to reach a satisfactory and quality offer adjusted to their needs.Este artículo se centra en el turismo senior, que no ha ocupado un lugar muy destacado hasta el momento, y que sin embargo, presenta grandes oportunidades para el mercado turístico. Hasta ahora la literatura existente sobre esta nueva modalidad es escasa y revela una falta de consenso conceptual, por lo que en el presente trabajo se busca una clarificación del mismo. También se profundiza en las motivaciones, comportamiento y fuentes de información utilizadas por los senior, variables de gran interés para lograr una oferta satisfactoria, de calidad y que se ajuste a sus necesidades

Simultaneous production of carotenoids and chemical building blocks precursors from chlorophyta microalgae

Replacement of fossil fuels has to be accompanied by the incorporation of bio-based procedures for the production of fine chemicals. With this aim, the microalga Chlamydomonas reinhardtii was selected for its ability to accumulate starch, an environmentally-friendly alternative source of chemical building blocks, such as 5′ -hydroxymethylfurfural or levulinic acid. The content of appreciated lipophilic coproducts was assessed in the selected microalga cultured at different nutritional conditions; and the parameters for the acidic hydrolysis of the algal biomass, obtained after pigments extraction, were optimized using a Central Composite Design. Response Surface Methodology predicted that the optimal hydrolysis conditions were elevated temperature, high DMSO % and short hydrolysis time for glucose. LA was favored at long times and high acid % and 5′ -HMF at lower acid % and high DMSO %. Chlamydomonas can therefore be used as a sustainable feedstock for the simultaneous production of high-added value lipophilic compounds and platform chemicals.Funding for open access charge: Universidad de Huelva / CBUA

Biomass valorization by using a sequence of acid hydrolysis and pyrolysis processes. Application to Leucaena leucocephala

Among main ways to provide an environmentally friendly energy and platform chemicals are the lignocellulosic conversion processes. The proper execution of this way will depend on the correct selection of lignocellulosic materials. A compelling plant is Leucaena leucocephala because its great variety of uses, its high biomass production and its leguminous nature. In this study, acid hydrolysis (130-170°C and 0.5-2% H2SO4, to extract valuable hemicelluloses) as pretreatment and pyrolysis of the solid residue (to get a gaseous fuel) as treatment have been used in its valorization. A laboratory-scale reactor was used for the pyrolysis experiments (550ºC, N2) for both Leucaena leucocephala, as raw material, and the solid residues after hydrolysis process and raw material. The amounts of CO, CO2 and H2 found in the raw material are similar to those found in the solids obtained after the different studied hydrolysis conditions. Moreover, the thermal behavior of studied solids has been studied by thermogravimetric analysis under nitrogen atmosphere at different heating rates (5, 10, 15 and 20 ºC min-1). Activation energy for all samples has been obtained by the Flynn-Wall-Ozawa method. The optimum value, in which a high relationship between recoverable hemicelluloses fraction and H2 concentration is found, under medium hydrolysis temperature (150ºC) has been obtained and was independent of the amount of acid added to the hydrolysis process

Maximizing furfural concentration from wheat straw and Eucalyptus globulus by nonisothermal autohydrolysis

The autohydrolysis process as a method for selective extraction of hemicelluloses and conversion to furfural was proposed for lignocellulosic raw materials. Samples of wheat straw (WS) and Eucalyptus globulus (EG) were subjected to nonisothermal autohydrolysis, defined by temperature 180–240°C. Within a biorefinery scheme for the selected materials, the aim of this study is both (a) to optimize furfural processing technology to enable higher yields and improved productivity from EG and WS by autohydrolysis and (b) to not excessively degrade the remaining polymeric constituents (glucan) in solid to facilitate a potential later use. Differences in the rate of the dehydration reaction of xylose to furfural have been observed, and it is faster in the case of WS with respect to that observed for eucalyptus. In that form, 4.25 g/100 g raw material (26% of the initial xylan in WS) could be found at 220°C, and an increase in the temperature (240°C) yielded 4.54 g/100 g raw material, 28% of the initial xylan. In EG, the increase in the hydrolysis temperature (240°C) yielded liquor with higher contents of furfural (4.45 g/100 g raw material, 25% of the initial xylan) and acetic acid (4.49 g/100 g raw material) and smaller contents of arabinose and xylan. In WS, a faster dehydration is found

Integral valorization of tagasaste (Chamaecytisus proliferus) under thermochemical processes

The generation of compounds derived from lignocellulosic biomass fractionation has a boost in recent years. An interesting plant could be tagasaste (Chamaecytisus proliferus) due to its high biomass production and its leguminous nature. A sequence of acid hydrolysis, as pretreatment, and pyrolysis of the solid residue, as treatment, has been used in its valorization. An experimental design (H2SO4 acid concentration 0.5–2%, temperature 130–170 °C, and time 30– 60 min) has been used to study the hydrolysis process. In the proposed acid hydrolysis process, under 170 °C as operational temperature, 0.5% of H2SO4 and 30 min for the operation time, 91.75% of the initial xylose have been extracted. The thermal behavior of both tagasaste trunks-large branches and some solid residues after hydrolysis (furthest and center points in the experimental design) process and raw material have been studied by thermogravimetric analysis under nitrogen atmosphere at different heating rates (5, 10, 15, and 20 °C min−1). The thermal degradation of the studied materials is influenced by its initial composition. Then, the higher reactivity of hemicelluloses can accelerate the pyrolysis degradation reaction. However, higher cellulose content implies lower activation energy in pyrolysis process

Bioactive pectic polysaccharides from bay tree pruning waste: Sequential subcritical water extraction and application in active food packaging

The potential isolation of bio-active polysaccharides from bay tree pruning waste was studied using sequential subcritical water extraction using different time-temperature combinations. The extracted polysaccharides were highly enriched in pectins while preserving their high molecular mass (10–100 kDa), presenting ideal properties for its application as additive in food packaging. Pectin-enriched chitosan films were prepared, improving the optical properties (=95% UV-light barrier capacity), antioxidant capacity (?95% radical scavenging activity) and water vapor permeability (=14 g·Pa-1·s-1·m-1·10-7) in comparison with neat chitosan-based films. Furthermore, the antimicrobial activity of chitosan was maintained in the hybrid films. Addition of 10% of pectins improved mechanical properties, increasing the Young's modulus 12%, and the stress resistance in 51%. The application of pectin-rich fractions from bay tree pruning waste as an additive in active food packaging applications, with triple action as antioxidant, barrier, and antimicrobial has been demonstrated.Authors would like to thank the Spanish Ministry of Science and Innovation (Ramon y Cajal contract RYC-2015-17109) and Universidad de Cordoba, ´ Spain (Predoctoral Grant 2019) for the financial support during this work

Search for optimum conditions of wheat straw hemicelluloses cold alkaline extraction process

A method for the selective extraction of hemicellulose from wheat straw involving cold alkaline extraction and subsequent separation by precipitation with ethanol is proposed. Wheat straw affords selective separation of the hemicellulose fraction from the cellulose and lignin fractions with the proposed method. The hemicellulose yield was optimized by using a 2n factor design to examine the influence of temperatures (temperature was designed between 20 and 40 ◦C), operation times (operation time was designed between 30 and 60 min) and alkali concentrations (alkali concentration was designed between 80 and 120 g L−1). These conditions allowed 56.1% of all hemicellulose initially present in the raw material, and 59.1% of the lignin, to be extracted. Subsequent separation of hemicellulose in the liquid phase from the cold alkaline extraction by precipitation with ethanol provided a fraction containing 39.4% of all hemicellulose (45.2% hemicellulose in extract/total extract) and only 12% of all lignin in the raw material.The authors are grateful for the FPU grant from the Spanish Ministry of Education. Also they thank to Spanish Ministry of Economy and Competitiveness (former Ministry of Science and Innovation) contracts. The authors acknowledge financial support for this investigation has been provided by CDTI (CENIT-E-CDTI-BioSos-CEN-2009-1040) and supported by Ministry of Economy and Competitiveness, "Local Investment fund for employment". Government of Spain, Junta de Andalucia, CICYT-FEDER (Science and Technology Inter Ministerial Commission, Spanish Government - European Regional Development Fund), project number AGL2009-13113 and the business group ACCIONA INFRAESTRUCTURAS, S.A

PERSPECTIVA PSICOSOCIAL DE LOS DERECHOS HUMANOS

Hoy en día es imprescindible abordar el problema de los derechos desde una perspectiva holística que integre la posición que el individuo ocupa en la sociedad y el impacto de los hechos sociales sobre su persona. Esta perspectiva va por lo tanto más allá del enfoque clásico de las violaciones a los derechos civiles y políticos de los ciudadanos sino, también incluye sus derechos económicos, sociales y culturales. Cualquier enfoque de tipo holístico debe entender al ser humano en su ambiente, social, cultural, natural y en función a todas las estructuras existentes, por más sutiles que sean o invisibles que parezcan. Precisamente este libro permite apreciar la dimensión amplia y compleja del ser en sociedad y las interacciones que de ambas partes se generan y las ramificaciones que producen. No es un ejercicio fácil y los editores de este volumen han logrado un salto cuántico al poder congregar en un solo espacio miradas que en otras circunstancias podrían haber sido opuestas y hasta contrarias a nuestra comprensión de problemas que, en efecto, tienen raíces comunes. El libro está dividido en 5 secciones, El espíritu de los tiempos actuales y los Derechos Humanos, Construcción ciudadana y ejercicio de los Derechos Humanos, Violaciones a Derechos Humanos, victimizaciones y su atención, Ejercicio de los Derechos Humanos y situaciones disruptivas y Defensa y defensores de Derechos Humanos.Manuel Gutiérrez Romero Jessica Ruiz Magañ

Practical guideline for Benign paroxismal positional vertigo

Introduction and objective: Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vertigo, characterized by brief attacks of rotatory vertigo associated with nystagmus, which are elicited by specific changes in head position relative to gravity. The observation of positional nystagmus is essential for the diagnosis of BPPV. The treatment consists in maneuvers of canalith repositioning procedure to move otoconial debris from the affected semicircular canal to the utricle. These guidelines are intended for all who treat the BPPV in their work, with an intention to assist in the diagnosis and application of an appropriate therapeutic method. Method: The experience and analysis of different national and international consensus on BPPV, has allowed to a large group of ENT specialists of the Communities of Castilla y León, Cantabria and La Rioja (Spain), carry out this guide. Results: The different clinical entities are reviewed. BPPV of the posterior semicircular canal, horizontal canal and anterior canal, BPPV affecting several canals, atypical and central BPPV, subjective BPPV and the characteristics of this process in the elderly. Canalith repositioning procedures have been illustrated with explanatory drawings. Discussion and conclusions: Although the pathophysiology of BPPV is canalolithiasis comprising free-floating otoconial debris within the endolymph of a semicircular canal, or cupulolithiasis comprising otoconial debris adherent to the cupula, there are still many issues to be resolved. We think that the best way to find answers is part of using a common methodology in the diagnosis and treatment of these patients.Introducción y Objetivo: El vértigo periférico más frecuente es el Vértigo Posicional Paroxístico Benigno (VPPB), caracterizado por bruscos ataques de sensación rotatoria, que aparecen como consecuencia de determinados cambios en la posición de la cabeza con relación a la gravedad. La observación del nistagmo posicional es fundamental para el diagnóstico de VPPB. El tratamiento consiste en aplicar maniobras de reposición, para intentar trasladar los restos otoconiales libres, desde el conducto semicircular (CS) afectado hasta el utrículo. Esta guía, está orientada para quienes tratan el VPPB, con la intención práctica de ayudarles en el diagnóstico y tratamiento de esta enfermedad. Método: La experiencia y el análisis de diferentes acuerdos nacionales e internacionales sobre el VPPB, han permitido a un amplio grupo de especialistas ORL de las Comunidades de Castilla y León, Cantabria y La Rioja (España), llevar a cabo esta guía. Resultados: Se revisan las diferentes entidades clínicas. VPPB del conducto semicircular posterior (CSP), horizontal (CSA) y anterior (CSA), incluyéndose también el VPPB multicanal, VPPB atípico y central, VPPB subjetivo y las características de este proceso en el anciano. Las maniobras de reposición se han ilustrado con dibujos explicativos. Discusión y conclusiones: Aunque la fisiopatología del VPPB se explica por la presencia de restos otoconiales libres en la endolinfa de uno o varios conductos semicirculares (canalitiasis) y en algunos casos por su adherencia a la cúpula del CS (cupulolitiasis), aún quedan muchas cuestiones por resolver. Pero creemos que la mejor manera de encontrar respuestas parte de utilizar una metodología común en el diagnóstico y tratamiento de estos pacientes