78 research outputs found

    Water balance on the Central Rift Valley

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    Material complementari del cas estudi "Water balance on the Central Rift Valley", part component del llibre "Case studies for developing globally responsible engineers"Peer ReviewedPostprint (author's final draft

    Water resources management in the Central Rift Valley: modelling for the water poor

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    Achieving a sustainable development is crucial, but is even more important in developing countries, where a wide number of people does not have a safe and secure access to water and relay on the environment to sustain their lives. The Ethiopian Central Rift Valley basin is already a degraded basin from the environmental point of view: ecosystems are endangered due to human activities there developed. Moreover, poverty is widespread all over the basin, with population is mainly living from agriculture on a subsistence economy. In order to achieve sustainable development to increase population incomes without affecting lives of those who are highly dependent on the environment and Integrated Water Resources Management approach shall be applied. First step has been to model the basin water resources, using the Soil and Water Assessment Tool (SWAT), which, after calibration and validation of the model, has given correct results. In order to follow deepening in the IWRM approach, more information on actual and future water demand and specifically water applied to agriculture will be needed.Postprint (published version

    Biomarkers and De Novo Protein Design Can Improve Precise Amino Acid Nutrition in Broilers

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    [EN] Almost half of the protein ingested by broilers is not retained and is excreted, impairing the nitrogen utilization, health and productivity of the animals, and intensifying the environmental impact of poultry meat production. This work proposes two potential tools, combining traditional nutrition with biotechnological, metabolomics, computational and protein engineering knowledge, which can contribute to improving precise amino acid nutrition in broilers in the future: (i) the use of serum uric nitrogen content as a rapid biomarker of amino acid imbalances, and (ii) the design and modeling of de novo proteins that are fully digestible and fit exactly to the animal's requirements. Both tools can open up new opportunities to form an integrated framework for precise amino acid nutrition in broilers, helping us to achieve more efficient, resilient, and sustainable production. This information can help to determine the exact ratio of amino acids that will improve the efficiency of the use of nitrogen by poultry. Precision nutrition in broilers requires tools capable of identifying amino acid imbalances individually or in groups, as well as knowledge on how more digestible proteins can be designed for innovative feeding programs adjusted to animals' dynamic requirements. This work proposes two potential tools, combining traditional nutrition with biotechnological, metabolomic, computational and protein engineering knowledge, which can contribute to improving the precise amino acid nutrition of broilers in the future: (i) the use of serum uric nitrogen content as a rapid biomarker of amino acid imbalances, and (ii) the design and modeling of de novo proteins that are fully digestible and fit exactly to the animal's requirements. Each application is illustrated with a case study. Case study 1 demonstrates that serum uric nitrogen can be a useful rapid indicator of individual or group amino acid deficiencies or imbalances when reducing dietary protein and adjusting the valine and arginine to lysine ratios in broilers. Case study 2 describes a stepwise approach to design an ideal protein, resulting in a potential amino acid sequence and structure prototype that is ideally adjusted to the requirements of the targeted animal, and is theoretically completely digestible. Both tools can open up new opportunities to form an integrated framework for precise amino acid nutrition in broilers, helping us to achieve more efficient, resilient, and sustainable production. This information can help to determine the exact ratio of amino acids that will improve the efficiency of the use of nitrogen by poultry.Cambra López, M.; Marín-Garcia, PJ.; Lledó, C.; Cerisuelo, A.; Pascual Amorós, JJ. (2022). Biomarkers and De Novo Protein Design Can Improve Precise Amino Acid Nutrition in Broilers. Animals. 12(7):1-16. https://doi.org/10.3390/ani1207093511612

    Surface functionalization of graphene oxide with tannic acid: Covalent vs non-covalent approaches

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    Graphene oxide (GO) is gaining a lot of interest in material science, biomedicine and biotechnology due to its outstanding physical properties, combined with its surface functionalization capacity, processability in aqueous media and biocompatibility. However, van der Waals forces among GO layers result in aggre-gation, yet its dispersion, large-scale production, and reinforcing efficiency remain challenging. Herein, simple and environmentally friendly methods via covalent and non-covalent routes have been developed to exfoliate and prepare surface-functionalized GO nanosheets with tannic acid (TA), a biological macro-molecule with antioxidant activity. Four esterification strategies were tested: direct, carbodiimide acti-vated, oxalyl chloride acylation and via an acid-functionalized GO intermediate. The resulting samples have been extensively characterized to get knowledge on the GO-TA interactions and the degree of graft-ing, as well as their surface topography, level of hydrophilicity, solubility/dispersibility, thermal and antibacterial properties. The covalent grafting of TA renders the GO surface more hydrophobic, resulting in improved dispersion in organic solvents. Besides, TA acts as a crosslinker between the GO nanosheets, leading to higher thermal resistance. A synergistic effect of both GO and TA on inhibiting bacterial growth has also been found. The esterification via carbodiimide leads to the highest grafting degree, the best thermal stability and the most effective antibacterial activity. This work not only highlights the great potential of TA for both exfoliation and surface functionalization of GO, but also extends its applications in biomedicine and for the development of green nanocomposites. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

    Easy, fast, and clean fluorescence analysis of tryptophan with clays and graphene/clay mixtures

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    Clays (C) such as sepiolite (SEP) or bentonite (BEN) and their mixtures with graphene (G) have been used as sorbents in dispersive solid phase extraction (dSPE). Tryptophan (TRP) analysis by fluorescence combined with a sample preparation step using G/C 30/70 w/w mixture provides a quantitative TRP retention, independently of the amino acid concentration with a desorption process feasible in 80 mM aqueous solution of the surfactant Brij L23. Under these conditions, the detection and quantification limits are 3.5 and 11.8 mu g L-1, respectively. Additionally, a novel, simple and inexpensive method has been developed to directly analyse TRP in real sam-ples, in which the presence of matrix interferents typically limits to obtain accurate results. For the first time, BEN has been used as an effective clean-up sorbent for the fluorimetric analysis of TRP in beer, leading to results without statistical differences versus those of a reference HPLC method free of interferences, with recoveries of 90 % and 100 %. The proposed method can be applied to accurately analyse TRP in complex matrices in a direct, easy, fast and sustainable way.Ministerio de Innovación, Ciencia y Universidade

    Graphene-Based Sensors for the Detection of Bioactive Compounds: A Review

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    Over the last years, different nanomaterials have been investigated to design highly selective and sensitive sensors, reaching nano/picomolar concentrations of biomolecules, which is crucial for medical sciences and the healthcare industry in order to assess physiological and metabolic parameters. The discovery of graphene (G) has unexpectedly impulsed research on developing cost-effective electrode materials owed to its unique physical and chemical properties, including high specific surface area, elevated carrier mobility, exceptional electrical and thermal conductivity, strong stiffness and strength combined with flexibility and optical transparency. G and its derivatives, including graphene oxide (GO) and reduced graphene oxide (rGO), are becoming an important class of nanomaterials in the area of optical and electrochemical sensors. The presence of oxygenated functional groups makes GO nanosheets amphiphilic, facilitating chemical functionalization. G-based nanomaterials can be easily combined with different types of inorganic nanoparticles, including metals and metal oxides, quantum dots, organic polymers, and biomolecules, to yield a wide range of nanocomposites with enhanced sensitivity for sensor applications. This review provides an overview of recent research on G-based nanocomposites for the detection of bioactive compounds, providing insights on the unique advantages offered by G and its derivatives. Their synthesis process, functionalization routes, and main properties are summarized, and the main challenges are also discussed. The antioxidants selected for this review are melatonin, gallic acid, tannic acid, resveratrol, oleuropein, hydroxytyrosol, tocopherol, ascorbic acid, and curcumin. They were chosen owed to their beneficial properties for human health, including antibiotic, antiviral, cardiovascular protector, anticancer, anti-inflammatory, cytoprotective, neuroprotective, antiageing, antidegenerative, and antiallergic capacity. The sensitivity and selectivity of G-based electrochemical and fluorescent sensors are also examined. Finally, the future outlook for the development of G-based sensors for this type of biocompounds is outlined

    Bioactive trans-resveratrol as dispersant of graphene in water. Molecular interactions

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    Currently, the preparation of high-quality graphene (G) dispersions is crucial due to the increasing demand for this nanomaterial in a wide range of industries. However, given the strong 7C-7C stacking tendency between G sheets, dispersant agents such as surfactants or polymers are required to attain stable and homogenous disper-sions in liquid media. In the present work, the effectiveness of resveratrol (RV), a fluorescent bioactive compound with antioxidant activity, as a dispersing agent for G in aqueous solutions was assessed. The interaction between G and RV was investigated via absorbance, fluorescence and Raman measurements. Dispersions were prepared via bath sonication, followed by probe ultrasonication and centrifugation, though the two last stages have little effect on the dispersion quality. The addition of G causes a quenching on RV fluorescence, and its magnitude raises with increasing G concentration, being the effect stronger up to 10 mg L-1. The change in the centrifugation speed and time have hardly influence on the RV fluorescence in the presence of G. The RV content remaining in the bulk solution after G dispersion, measured via UV-Vis absorption, decreases linearly with increasing G concentration. RV can effectively disperse all the G present in the sample up to 10 mg L-1; at higher concen-trations, the dispersing ability slightly decreases, and the G content is distributed between the bulk solution and the centrifuged residue. Besides, the fluorescence of RV dispersed in G is much higher in methanol than in an aqueous medium. TEM analysis confirms the good exfoliation of G upon ultrasonication in RV solutions and indicates that the layer thickness depends on the G/RV ratio. The results of this study could open new per-spectives for using natural products like resveratrol as biocompatible and efficient dispersing agents of G to be used in numerous applications, especially in biomedicine.Ministerio de Ciencia, Innovación y Universidade

    Graphene Oxides Derivatives Prepared by an Electrochemical Approach: Correlation between Structure and Properties

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    Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this study, electrochemically exfoliated graphene oxides (EGOs) with different amounts of surface groups, hence level of oxidation, were prepared by an electrochemical two-stage approach using graphite as raw material. A complete characterization of the EGOs was carried out in order to correlate their surface topography, interlayer spacing, defect content, and specific surface area (SSA) with their electrical, thermal, and mechanical properties. It has been found that the SSA has a direct relationship with the d-spacing. The EGOs electrical resistance decreases with increasing SSA while rises with increasing the D/G band intensity ratio in the Raman spectra, hence the defect content. Their thermal stability under both nitrogen and dry air atmospheres depends on both their oxidation level and defect content. Their macroscopic mechanical properties, namely the Young's modulus and tensile strength, are influenced by the defect content, while no correlation was found with their SSA or interlayer spacing. Young moduli values as high as 54 GPa have been measured, which corroborates that the developed method preserves the integrity of the graphene flakes. Understanding the structure-property relationships in these materials is useful for the design of modified GOs with controllable morphologies and properties for a wide range of applications in electrical/electronic devices

    Tailorable synthesis of highly oxidized graphene oxides via an environmentally friendly electrochemical process

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    Graphene oxide (GO) is an attractive alternative to graphene for many applications due to its captivating optical, chemical, and electrical characteristics. In this work, GO powders with a different amount of surface groups were synthesized from graphite via an electrochemical two-stage process. Many synthesis conditions were tried to maximize the oxidation level, and comprehensive characterization of the resulting samples was carried out via elemental analysis, microscopies (TEM, SEM, AFM), X-ray diffraction, FT-IR and Raman spectroscopies as well as electrical resistance measurements. SEM and TEM images corroborate that the electrochemical process used herein preserves the integrity of the graphene flakes, enabling to obtain large, uniform and well exfoliated GO sheets. The GOs display a wide range of C/O ratios, determined by the voltage and time of each stage as well as the electrolyte concentration, and an unprecedented minimum C/O value was obtained for the optimal conditions. FT-IR evidences strong intermolecular interactions between neighbouring oxygenated groups. The intensity ratio of D/G bands in the Raman spectra is high for samples prepared using concentrated H2SO4 as an electrolyte, indicative of many defects. Furthermore, these GOs exhibit smaller interlayer spacing than that expected according to their oxygen content, which suggests predominant oxidation on the flake edges. Results point out that the electrical resistance is conditioned mostly by the interlayer distance and not simply by the C/O ratio. The tuning of the oxidation level is useful for the design of GOs with tailorable structural, electrical, optical, mechanical, and thermal properties.Ministerio de Ciencia, Innovacion y Universidade

    El portafolio digital como herramienta de aprendizaje en la construcción de contenidos

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    El presente trabajo describe la experiencia realizada con el alumnado de los Grados de Maestro de Educación Infantil y Maestro de Educación Primaria a través de la utilización del Blog como portafolio digital en la construcción de los aprendizajes teórico-prácticos. Con el objetivo de valorar los aprendizajes adquiridos con esta nueva metodología, se ha diseñado un cuestionario ad hoc que recoge 20 preguntas con categorías de respuesta en formato Likert, referidas en una primera parte a aspectos relacionados con el contacto que tiene el alumnado con las redes sociales y por otra, el grado de satisfacción y motivación de los aprendizajes realizados. Han participado un total de 64 estudiantes de primer curso (37 del Grado de EI de la asignatura Organización del aula de la Educación Infantil de 0-3 y de 3ª 6 años y 27 de la asignatura Gestión e Innovación en contextos educativos del Grado de educación Primaria). Los resultados manifiestan acuerdos satisfactorios con los aprendizajes realizados, referido al aspecto motivacional como también, en índices bastante superiores sobre la comprensión y recuerdo de los contenidos trabajados. A modo de conclusión, destacamos la apuesta por la inclusión de las TIC en las prácticas docentes universitarias como mejora y calidad de los aprendizajes
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