2,416 research outputs found

    l-Amino Acid Production by a Immobilized Double-Racemase Hydantoinase Process: Improvement and Comparison with a Free Protein System

    Get PDF
    Protein immobilization is proving to be an environmentally friendly strategy for manufacturing biochemicals at high yields and low production costs. This work describes the optimization of the so-called “double-racemase hydantoinase process,” a system of four enzymes used to produce optically pure l-amino acids from a racemic mixture of hydantoins. The four proteins were immobilized separately, and, based on their specific activity, the optimal whole relation was determined. The first enzyme, d,l-hydantoinase, preferably hydrolyzes d-hydantoins from d,l-hydantoins to N-carbamoyl-d-amino acids. The remaining l-hydantoins are racemized by the second enzyme, hydantoin racemase, and continue supplying substrate d-hydantoins to the first enzyme. N-carbamoyl-d-amino acid is racemized in turn to N-carbamoyl-l-amino acid by the third enzyme, carbamoyl racemase. Finally, the N-carbamoyl-l-amino acid is transformed to l-amino acid by the fourth enzyme, l-carbamoylase. Therefore, the product of one enzyme is the substrate of another. Perfect coordination of the four activities is necessary to avoid the accumulation of reaction intermediates and to achieve an adequate rate for commercial purposes. The system has shown a broad pH optimum of 7–9, with a maximum activity at 8 and an optimal temperature of 60 °C. Comparison of the immobilized system with the free protein system showed that the reaction velocity increased for the production of norvaline, norleucine, ABA, and homophenylalanine, while it decreased for l-valine and remained unchanged for l-methionine

    A new manual wheelchair propulsion system with self-locking capability on ramps

    Get PDF
    A wheelchair user faces many difficulties in their everyday attempts to use ramps, especially those of some length. The present work describes the design and build of a propulsion system for manual wheelchairs for use in ascending or descending long ramps. The design is characterized by a self-locking mechanism that activates automatically to brake the chair when the user stops pushing. The system consists of a planetary transmission with a self-locking capacity coupled to a push rim with which the user moves the system. Different transmission ratios are proposed, adapted to the slope and to the user’s physical capacity (measured as the power the user can apply over ample time periods). The design is shown to be viable in terms of resistance, and approximate dimensions are established for the height and width of the propulsion system. Also, a prototype was built in order to test the self-locking system on ramps

    Labor Demand and Information Technologies: Evidence for Spain, 1980-2005

    Get PDF
    Using the EU KLEMS dataset we test the capital-skill complementarity hypothesis in a cross-section of sectors in Spain between 1980 and 2005. We analyze three groups of workers, who are classed according to skill level: high, medium and low. Capital assets have been broken down into ICT (information and communication technologies) assets and non-ICT assets. Acquisition and usage costs of ICT assets declined throughout the period studied, both in absolute terms and relative to the other capital assets and workers. Our principal finding is that the substitutibility between workers and ICT assets falls as worker skill level rises. In fact, the ICT assets were strongly complement with highly skilled workers and were not substitutive with them. Throughout the period analyzed, the fraction of employed medium- and high-skill workers rose by 21% and 12%, respectively, to the disadvantage of low-skill workers. After decomposing these changes, we found that the latter were dominated by an ajustment within sectors more than by a composition effect or adjustment between sectors. These adjustments may be explained by reference to the estimated elasticities of substitution.capital-skill complementarity, ICT, translog cost function, elasticity of substitution.

    A spatial contextual postclassification method for preserving linear objects in multispectral imagery

    Get PDF
    Classification of remote sensing multispectral data is important for segmenting images and thematic mapping and is generally the first step in feature extraction. Per-pixel classification, based on spectral information alone, generally produces noisy classification results. The introduction of spatial information has been shown to be beneficial in removing most of this noise. Probabilistic label relaxation (PLR) has proved to be advantageous using second-order statistics; here, we present a modified contextual probabilistic relaxation method based on imposing directional information in the joint probability with third-order statistics. The proposed method was tested in synthetic images and real images; the results are compared with a "Majority" algorithm and the classical PLR method. The proposed third-order method gives the best results, both visually and numerically

    Barley and yeast β-glucans as new emulsifier agents for the development of aqueous natural antifungal formulations

    Get PDF
    Producción CientíficaBarley and yeast β-glucans were selected, together with lecithin, to encapsulate resveratrol by emulsification-evaporation method to develop new and safer antifungal formulations. Different emulsification techniques were used: high-shear, high pressure and high pressure and temperature emulsification. Morphology, crystallinity, encapsulation efficiency and in vitro antifungal activity against Botrytis cinerea of the different formulations were evaluated. No significant differences between each emulsification procedure in particle size (below 90 nm) and in encapsulation efficiency (70–100%) were observed; only barley β-glucan emulsions showed lower efficiency due to the formation of a gel that retained most of the active compound. A great influence of the emulsification method and the encapsulating material on the crystallinity of the particles was observed. The highest antifungal activity (up to 53% growth inhibition) was obtained by the formulations with yeast β-glucans, indicating an enhanced absorption of encapsulated resveratrol through the cell wall of the fungus at the presence of (1–3, 1–6)-β-glucans.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA040U16

    The circular economy strategy in hospitality: A multicase approach

    Full text link
    The circular economy (CE) is considered a possible solution to problems, such as the increasing global demand for resources, climate change and worldwide pollution. CE can help to transform the hospitality industry from its current linear model of production to a circular one. However, there is a lack of research on circular tourism, therefore, this paper’s main purpose is to shed light on CE strategies—reduction, reuse, recycle, redesign, replace and rethink—developed in the tourism sector, as well as the tourism sector’s CE initiatives by means of a business case analysis method. This qualitative multicase analysis allows us to comprehend the CE practices deployed by large hotel chains, thus identifying the CE strategies and best practices. The results show that the main strategies adopted are the reduction, recycle and reuse, in this order. Nevertheless, the remaining strategies have yet to be adopted in the mainstream. This research emphasises the need to promote the CE in the hospitality industry, especially among independent hotels.This work was supported by the Ministry of Science, Innovation and Universities of Spain within its National Program for Research Aimed at the Challenges of Society under grant ECO2016-79659-R (Ecoinnovation and Circular Economy in Services Industries

    Radio does not die on the air: Podcasting and on-demand broadcast strategies among speech-based radio stations

    Get PDF
    In recent decades, speech-based radio stations in Spain, whose programmes have been aimed at the general public, have transformed their on-demand content broadcasting strategy by incorporating audio processes in the form of podcasts, followed by transmission through websites, aggregators and applications. The overall objective of this article is to provide a detailed account of the evolution and scope of the podcast as an on-demand distribution channel for speech-based Spanish radio broadcasters, and to reveal how this format is changing the approaches taken by the most prominent national radio stations [Cadena SER, COPE, Onda Cero, and Radio Nacional de España (RNE)], with special emphasis on prime-time morning shows. The methodology employed combines quantitative and qualitative techniques along with an analysis of the content uploaded to the website of these morning programmes, which are part of the weekly programming cycle, together with semi-structured interviews using closed-ended questions that have been given to the main heads of programming and digital areas of the broadcasters under study. The results show that radio stations have incorporated podcast distribution into their usual routine in order to give new life to the content emitted, with the aim of serving both traditional users as well as new generations of digitised native listeners. In addition, they process daily content in an increasingly systematic way, on the basis of a model of mixed management coordination between programmes and digital areas. Similarly, broadcasters have made considerable progress in the measurement and analysis of the time-shifted audience, as well as in broadcast multiplication techniques using push notifications, social media, and monetisation

    Creación de una plataforma de servicios de siniestros orientada al cliente

    Get PDF
    Màster de Direcció d'Entitats Asseguradores i Financeres, Universitat de Barcelona, Facultat d'Economia i Empresa, Curs: 2007-2008, Tutor: Félix Tarradellas BertránEste trabajo resume una forma de ordenar y organizar el área de siniestros, teniendo como máxima romper el axioma imperante en el subconsciente de que la satisfacción del cliente y la contención del coste medio son variables inversamente proporcionales. Con este enfoque se desarrolla una propuesta pensada para el cliente y por el cliente que pretende ser innovadora y de suma sencillez “por fuera” para el cliente, no exenta de complejidad “de puertas a dentro”. Cómo ofrecer un “front” al cliente, cercano y que le entienda, exento de complejidad técnica y jerga aseguradora, que le transmita transparencia y confianza. Cómo compatibilizarlo con la contención del coste de los siniestros, y la reducción del coste de gestión. Este trabajo se presenta como un ejercicio práctico, novedoso y real de cómo dar solución a este gran problema que el sector afronta, transformando completamente una organización y poniéndola al servicio del cliente

    The role of institutional engagement at the macro level in pushing the circular economy in Spain and its regions

    Full text link
    Currently, the European Union is promoting the circular economy, a change that involves moving the foundations of actual economies toward the most sustainable production and consumption periods, in which the reuse of resources predominates, mainly through recycling, reuse, and reduction, among other strategies. This study, through the application of institutional theory, analyzes the role that institutional pressure has in the diffusion and adoption of the circular economy from the state to the regions inside through coercive, normative, and mimetic pressures. A matrix of institutional positioning was developed that analyzes the number and diversity of circular economy initiatives. The results show that coercive pressure followed by mimetic pressure are the most relevant in explaining the development of the circular economy in Spain in relation to the closest other European countries in Southern Europe, while there is low normative pressure. The results obtained provide relevant information on how to accelerate the development of the circular economy throughout the European Union through the adequate exercise of different types of institutional pressure.This research was supported by the Ministry of Science, Innovation and Universities of Spain within its National Program for Research Aimed at the Challenges of Society. [Grant ECO2016-79659-R (Ecoinnovation and Circular Economy in the service sector)

    COVID-19 impacts and recovery strategies: The case of the hospitality industry in Spain

    Full text link
    The health crisis caused by the pandemic COVID-19 has been of such magnitude that the drop-off in economic and tourist activity in most countries is generating an economic crisis with consequences that are still difficult to measure. The present work analyses the origins and evolution of the coronavirus pandemic and reviews the literature related to the impacts and recovery strategies that were implemented in previous crisis situations affecting the hotel industry. In order to focus the study on one country, Spain was selected based on tourism indicators, the importance of tourism for this country and the importance of Spain as a leader in international tourist destinations. The influence of the pandemic on the Spanish tourism sector and, more specifically, on its hospitality industry is explored in depth. In addition, the main initiatives to support the tourism and hospitality sector that have been undertaken at the global, European and national levels are highlighted and, finally, the response and recovery strategies of the five largest Spanish hotel chains to guarantee a COVID-19-free stay in their facilities and to recover the accommodation activity are discussed.This research was funded by the Ministry of Science and Innovation of Spain within its National Program for Research Aimed at the Challenges of Society. (Grant ECO2016-79659-R (Eco-innovation and Circular Economy in the service sector)
    corecore