27 research outputs found

    Nuevas estrategias en la generaci贸n de hidr贸geno por fotocat谩lisis

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    RESUMEN: En el contexto provocado por la situaci贸n energ茅tica a nivel mundial, el hidr贸geno aparece como una buena alternativa como vector energ茅tico debido a que su combusti贸n solo produce agua. Actualmente la mayor parte del hidr贸geno es producido a trav茅s de reformado de vapor de combustibles f贸siles. Este proceso requiere altas temperaturas y presiones, lo que conlleva emisiones de CO2 asociadas al consumo energ茅tico. La fotocat谩lisis aparece como una v铆a para recolectar energ铆a solar y almacenarla como combustible solar. En esta tesis doctoral se han investigado nuevos desarrollos en producci贸n de hidr贸geno por fotocat谩lisis. Est谩 centrada en superar los principales retos de esta tecnolog铆a a trav茅s de diferentes estrategias. Siguiendo esta premisa, el TiO2 se combin贸 con 贸xido de grafeno reducido para mejorar su actividad fotocatal铆tica. El fotocatalizador sintetizado fue inmovilizado en una membrana polim茅rica a trav茅s de diferentes m茅todos. Posteriormente se evalu贸 la producci贸n de hidr贸geno de las membranas preparadas. Finalmente, se estudi贸 un sistema compuesto por una mol茅cula imitadora de la [Fe-Fe]-hidrogenasa como catalizador y puntos cu谩nticos de CdSe o CdTe como fotosensibilizadores.ABSTRACT: In the current global energy situation, hydrogen appears as a good alternative as energy vector because its combustion only produces water. Nowadays, most of the hydrogen is produced by steam reforming from fossil fuels which requires high temperatures and pressures, and contributes to CO2 emissions. Photocatalysis is a way to harvest the sunlight energy and store it as solar fuel. In this doctoral thesis novel developments in photocatalytic hydrogen production were investigated. It focused on overcoming the main challenges of this technology through different strategies. In this way, TiO2 was doped with reduced graphene oxide to improve its photocatalytic activity. The composite was immobilized on a polymeric membrane by different methods and the resulting materials were evaluated. Finally, a hybrid system composed of a [Fe-Fe]-hydrogenase mimic molecule as catalyst and CdSe or CdTe quantum dots as photosensitizers was investigated.This research has been financially supported by the Spanish Ministry of Economy and Competitiveness, Spanish State Research Agency and and the European Regional Development Fund through the projects: CTM2015-69845-R 鈥淣ew developments in photocatalysis for environmental applications鈥 (MINECO/FEDER, UE), CTQ2015-66078-R 鈥淢odeling of advanced separation applications鈥 (MINECO/FEDER, UE), 鈥淗YLANTIC鈥 EAPA_204/2016 and RTI2018-099407-B-I00 鈥淐hallenges in the implementation of photocatalysis for environmental applications鈥 (MICIU/AEI/FEDER, UE). The author has been the recipient of a predoctoral fellowship (FPI BES-2016-079201) granted by the Spanish Ministry of Education

    Prospective life cycle assessment of hydrogen production by waste photoreforming

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    Identifying sustainable energy vectors is perhaps one of the most critical issues that needs addressing to achieve a climate-neutral society by 2050. In this context, the hydrogen economy has been proposed as a solution to mitigate our current fossil-based energy system while the concept of the circular economy aims to boost the efficient use of resources. Photoreforming offers a promising opportunity for recycling and transforming widely available biomass-derived wastes (e.g., crude glycerol from biodiesel) into clean hydrogen fuel. This processing technology may be a versatile method that can be performed not only under UV light but also under visible light. However, this approach is currently at the lab-scale and some inherent challenges must be overcome, not least the relatively modest hydrogen production rates for the lamps? substantial energy consumption. This study aims to assess the main environmental impacts, identifying the hotspots and possible trade-off in which this technology could operate feasibly. We introduce an assessment of the windows of opportunity using seven categories of environmental impact with either artificial light or sunlight as the source of photocatalytic conversion. We compared the environmental indicators from this study with those of the benchmark water electrolysis and steam?methane reforming (SMR) technologies, which are currently operating at a commercial scale. The results obtained in this study situate biowaste photoreforming within the portfolio of sustainable H2 production technologies of interest for future development in terms of target H2 production rates and lifetimes of sustainable operation.Financial support from projects RTI2018-099407-B-I00 and RTI2018-099407-B-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER and by 鈥淓RDF A way of making Europe鈥 by the 鈥淓uropean Union鈥 is gratefully acknowledged. We would like also to thank MICIN for providing Marta Rumayor with a Juan de la Cierva postdoctoral contract IJCI-2017-32621

    Role of reactive oxygen species on the activity of noble metal-doped TiO2 photocatalysts

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    Modified TiO2 catalysts are of interest in environmental water remediation since they can lead to efficient electron-hole separation and greatly enhance the photocatalytic properties of TiO2. Reactive oxygen species (ROS), such as the superoxide radical (O2 鈭), hydroxyl radical ( OH), and positive valence band holes (h+VB), have been reported as the main oxidative species involved in photocatalytic degradation processes. In this work, the role of these species using TiO2, TiO2/Pt 0.5鈥痺t%, and TiO2/Ag 10鈥痺t% has been examined in order to clarify the oxidation pathways. For this purpose, the contribution of the main oxidative species was analyzed in the photocatalytic degradation of dichloroacetic acid (DCA) solutions using specific scavengers (benzoquinone, tert-butyl alcohol, and formic acid). Moreover, the hydroxyl radicals were quantitatively determined in order better understand the results. Regardless of the catalyst used, it is concluded that OH radicals are the major reactive species responsible for DCA degradation and no significant degradation is due to O2 鈭 radicals. Nevertheless, different OH generation pathways were found, depending on the nature of the catalysts. Degradation using TiO2 was conducted mainly via OH radicals generated in the positive holes, while noble metal-doped TiO2 catalysts generated OH radicals through the transformation of O2 鈭 radicals.Financial support through projects CTM2015-69845-R and CTQ2015-66078-R (MINECO/FEDER, UE) is gratefully acknowledged. Paula Ribao thanks the University of Cantabria for her research grant. Juan Corredor would also like to thank the FPI postgraduate research grant (BES-2016-079201)

    Performance of rGO/TiO2 photocatalytic membranes for hydrogen production

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    Although there are promising environmental and energy characteristics for the photocatalytic production of hydrogen, two main drawbacks must be overcome before the large- scale deployment of the technology becomes a reality, (i) the low efficiency reported by state of the art photocatalysts and, (ii) the short life time and difficult recovery of the photocatalyst, issues that need research and development for new high performance catalysts. In this work 2% rGO/TiO2 composite photocatalysts were supported over Nafion membranes and the performance of the photocatalytic membrane was tested for hydrogen production from a 20% vol. methanol solution. Immobilization of the composite on Nafion membranes followed three different simple methods which preserve the photocatalyst structure: solvent-casting (SC), spraying (SP), and dip-coating (DP). The photocatalyst was included in the matrix membrane using the SC method, while it was located on the membrane surface in the SP and DP membranes showing less mass transfer limitations. The performance of the synthesized photocatalytic membranes for hydrogen production under UVA light irradiation was compared. Leaching of the catalytic membranes was tested by measuring the turbidity of the solution. With respect to catalyst leaching, both the SC and SP membranes provided very good results, the leaching being lower with the SC membrane. The best results in terms of initial hydrogen production rate (HPR) were obtained with the SP and DP membrane. The SP was selected as the most suitable method for photocatalytic hydrogen production due to the high HPR and the negligible photocatalyst leaching. Moreover, the stability of this membrane was studied for longer operation times. This work helps to improve the knowledge on the application of photocatalytic membranes for hydrogen production and contributes in facilitating the large-scale application of this process.This research was funded by MCIU/AEI/FEDER UE (RTI2018-099407-B-I00, RTI2018-093310-B-I00 and RTC2019-006820-5)

    Primera evaluaci贸n bimestral bajo ambientes virtuales realizada al ciclo V de la I.E.D. Rafael Bernal Jim茅nez. 鈥淧or la transformaci贸n pedag贸gica"

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    Migration of Information and Communication Technologies (ICT) towards Learning and Knowledge Technologies (tac for its meaning in Spanish) and even more, towards Empowerment and Participation Technologies (tep for its meaning in Spanish), are generating radical changes in traditional school learning processes. Therefore, the article presents the results obtained in the design, planning and implementation of the first Bimonthly Virtual Assessment for the 5th cycle in the Educational District Institution (IED) Rafael Bernal Jim茅nez, in order to encourage the use of ict and a responsable and self-regulated training for learning processes through the Virtual Classroom Casquete de Esfera Perforada (http://casquetedeesferaperforada. com/plataforma2/).La migraci贸n de las tecnolog铆as de la informaci贸n y la comunicaci贸n (tic) hacia聽las tecnolog铆as para el aprendizaje y el conocimiento (tac) y, a煤n m谩s, hacia聽las tecnolog铆as para el empoderamiento y la participaci贸n (tep) est谩 generando聽cambios radicales en los procesos de aprendizaje escolar tradicional. Este art铆culo聽presenta los resultados obtenidos en el dise帽o, planeaci贸n e implementaci贸n聽de la primera evaluaci贸n virtual bimestral del ciclo V, en la Instituci贸n Educativa聽Distrital Rafael Bernal Jim茅nez, con el fin de incentivar el uso de las tic y la formaci贸n聽autorregulada y responsable en los procesos de aprendizaje, a trav茅s聽del aula virtual Casquete de Esfera Perforada (http://casquetedeesferaperforada.com/plataforma2/)

    Potential relation of cardiovascular risk factors to disease activity in patients with axial spondyloarthritis

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    Background: Axial spondyloarthritis (axSpA) patients are known to have a higher prevalence of several comorbidities, including, among others, an increased risk of atherosclerosis, hypertension, dyslipidemia, and diabetes. The purpose of the present study was to determine whether the sum of traditional cardiovascular (CV) risk factors is related to disease characteristics, such as disease activity, in patients with axSpA. Methods: A cross-sectional study that encompassed 804 patients with axSpA was conducted. Patients were assessed for the presence of five traditional CV risk factors (diabetes mellitus, dyslipidemia, hypertension, obesity, and smoking status), and disease activity measurements. A multivariable regression analysis was performed to evaluate whether the number of classic CV risk factors was independently associated with specific features of the disease, to include disease activity. Results: A multivariable analysis showed that Ankylosing Spondylitis Disease Activity Score-C reactive protein (ASDAS-CRP) activity score was significantly higher in patients with 1 [beta coefficient 0.3 (95% confidence interval (CI) 0.1-0.5), p = 0.001] and ?2 [beta coefficient 0.5 (95% CI 0.3-0.7), p = 0.000] CV risk factors compared with those without CV risk factors. Similarly, patients with 1 [OR 2.00 (95%CI 0.99-4.02), p = 0.053] and ?2 [OR 3.39 (95%CI 1.82-6.31), p = 0.000] CV risk factors had a higher odds ratio for the presence of high disease activity compared with the zero CV category. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) activity score was significantly associated with the number of CV risk factors, being higher in patients with more CV risk factors. These relationships showed a CV risk factor-dependent effect being beta coefficients and ORs higher for the effect of ?2 over 1 CV risk factor. Conclusion: Among patients with axSpA, as the number of traditional CV risk factors increased, disease activity similarly increases in an independent manner.Funding: The authors disclosed receipt of the following financial support for the research, authorship, and/ or publication of this article: This research was funded by a grant to MAG-G from the Instituto de Salud Carlos III (ISCIII) (Fondo de Investigaci贸n Sanitaria grants PI06/0024, PI09/00748, PI12/00060, PI15/00525, PI18/00043) and the ISCIII RETICS programs (RD12/0009 and RD16/0012)

    Vaspin in atherosclerotic disease and cardiovascular risk in axial spondyloarthritis: a genetic and serological study

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    Background: Vaspin is a novel anti-inflammatory adipokine associated with cardiovascular (CV) disease and inflammation in chronic inflammatory conditions different from axial spondyloarthritis (axSpA). Given the high incidence of CV disease (mainly due to accelerated atherosclerosis) exhibited by axSpA patients, we wondered if vaspin could also be a key molecule in this process. However, data on the role of vaspin regarding atherosclerotic disease in the context of axSpA is scarce. For this reason, we aimed to evaluate the implication of vaspin, at the genetic and serological level, in subclinical atherosclerosis and CV risk in axSpA. Methods: This study included 510 patients diagnosed with axSpA. Carotid ultrasound (US) was performed to evaluate the presence of subclinical atherosclerosis. Three vaspin gene variants (rs2236242, rs7159023, and rs35262691) were genotyped by TaqMan probes. Serum vaspin levels were assessed by enzyme-linked immunosorbent assay. Statistical analysis was performed using STATA庐 v.11.1. Results: Serum vaspin levels were significantly higher in female patients than in males and also in obese patients when compared to those with normal weight (p < 0.05). At the genetic level, we disclosed that the minor allele of rs2236242 (A) was associated with lower serum vaspin levels in axSpA, while the rs7159023 minor allele (A) was linked to higher serum levels (p < 0.05). When the three polymorphisms assessed were combined conforming haplotypes, we disclosed that the TGC haplotype related to high serum levels of vaspin (p = 0.01). However, no statistically significant association was observed between vaspin and markers of subclinical atherosclerosis, both at the genetic and serological level. Conclusions: Our results revealed that vaspin is linked to CV risk factors that may influence on the atherosclerotic process in axSpA. Additionally, we disclosed that serum vaspin concentration is genetically modulated in a large cohort of patients with axSpA.This work was partially supported by funds of a NEXT-VAL grant (NVAL17/10) (Instituto de Investigaci贸n Sanitaria IDIVAL) awarded to FG. RL-M is a recipient of a Miguel Servet type I programme fellowship (grant CP16/00033) from the 鈥淚nstituto de Salud Carlos III鈥 (ISCIII) and co-funded by the European Social Fund, ESF). SR-M is supported by funds of the RETICS Program (RD16/0012/0009) from ISCIII and co-funded by the European Regional Development Fund. VP-C is supported by a pre-doctoral grant from IDIVAL (PREVAL18/01). LL-G is supported by funds of a Miguel Servet type I programme fellowship from ISCIII (grant CP16/00033, co-funded by the ESF). OG is beneficiary of a grant funded by Xunta de Galicia, Conseller铆a de Educaci贸n, Universidade e Formaci贸n Profesional and Conseller铆a de Econom铆a, Emprego e Industria (GAIN), GPC IN607B2019/10

    Dise帽o de auriculares intraurales personalizados de altas prestaciones mediante t茅cnicas de fabricaci贸n avanzada

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    En el presente trabajo se explica y expone el proceso de ideaci贸n y desarrollo de unos auriculares intraurales personalizados que se adaptan a la morfolog铆a del o铆do de cada usuario. Se realiza un estudio de la t茅cnica, analizando la evoluci贸n de estos dispositivos a lo largo de la historia, su clasificaci贸n, su funcionamiento, sus componentes y sus caracter铆sticas t茅cnicas. Seguidamente se lleva a cabo un estudio de mercado mediante encuestas de usuario y an谩lisis de consultor铆as para determinar el tipo de auricular a dise帽ar y sus caracter铆sticas distintivas e innovadoras. Despu茅s de clasificar el dise帽o, se inicia el proceso de generaci贸n de ideas y se describe el uso de herramientas f铆sicas y digitales, as铆 como los procedimientos para llegar a la soluci贸n final. Entre ellos est谩 la ingenier铆a inversa, el modelado 3D, la fabricaci贸n aditiva y procesos de moldeo. Mediante estas t茅cnicas se logra desarrollar un dise帽o de auriculares con su prototipo correspondiente

    Comercializadora de productos para la construcci贸n: Tejares del pescadero

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    Para la realizaci贸n del presente estudio se plantean cuatro hip贸tesis que permiten determinar si es un proyecto viable o factible o no para los inversionistas de pasar elemento proyecto se encuentra por encima del costo del capital de los accionistas y su rentabilidad es atractiva para los inversionistas. Existe una demanda en el mercado para que sea atendida por el proyecto. El proyecto va a beneficiar a la empresa tejares del pescadero. 脡ste tipo investigaci贸n se justifica desde el punto de vista el beneficio para hacer el sector de la construcci贸n, al constituirse una nueva fuente de suministro de materiales.Estudio del sector de insumos para la construcci贸n. La importancia del sector. Aspectos m谩s destacados. Estudio t茅cnico de la producci贸n. Estudio de productos y competencia. Estudio econ贸mico. Evaluaci贸n del proyecto.Administrador de EmpresasPregradoEMM

    Apoyo al programa de contadur铆a publica en la sistematizaci贸n y digitalizaci贸n de documentos del plan de estudios.

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    El proyecto describe las actividades desarrolladas para el apoyo al programa de Contadur铆a Publica en la sistematizaci贸n y digitalizaci贸n de documentos. En este proyecto se muestra como el registro calificado de la Educaci贸n Superior certitlca el cumplimiento de las condiciones de calidad por parte de las instituciones de educaci贸n superior, como un reconocimiento otorgado por el Ministerio de Educaci贸n Nacional sobre las condiciones de calidad seg煤n la ley 1188 de 2008. El proyecto utilizo un tipo de estudio descriptivo. Donde se tom贸 como poblaci贸n al total de los datos existentes sobre el programa de contadur铆a publica desarrollado por estudiantes. desde el a帽o 2010 al a帽o 2013. Se logr贸 recopilar la informaci贸n existente del programa. para posteriormente clasificarla y escanear la documentaci贸n que existe en el programa. El proyecto sirvi贸 como apoyo al registro calificado del programa de contadur铆a publica en el desarrollo de una base de datos para los proyectos de gradoPregradoContador(a) Publico(a