110 research outputs found

    La intervención entre niveles educativos y flexibilidad en el empleo: una relación asimétrica

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    Synergistic effect of manganese (II) phosphate & diamond nanoparticles in electrochemical sensors for reactive oxygen species determination in seminal plasma

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    In this work, we explore the ability of manganese (II) phosphate (MnP) as a catalytic element for the determination of reactive oxygen species (ROS) in seminal plasma, when MnP is employed as modifier of a glassy carbon electrode. The electrochemical response of the manganese (II) phosphate-modified electrode shows a wave at around +0.65 V due to the oxidation of Mn2+ to MnO2+, which is clearly enhanced after addition of superoxide, the molecule considered as the mother of ROS. Once proved the suitability of manganese (II) phosphate as catalyst, we evaluate the effect of including a 0D (diamond nanoparticles) or a 2D (ReS2) nanomaterial in the sensor design. The system consisting of manganese (II) phosphate and diamond nanoparticles yielded the largest improvement of the response. The morphological characterization of the sensor surface was performed by scanning electron microscopy and atomic force microscopy, while cyclic and differential pulse voltammetry were employed for the electrochemical characterization of the sensor. After optimizing the sensor construction, calibration procedures by chronoamperometry were performed, leading to a linear relation between peak intensity and the superoxide concentration in the range of 1.1 10−4 M − 1.0 10−3 M with a limit of detection of 3.2 10−5 M. Seminal plasma samples were analysed by the standard addition method. Moreover, the analysis of samples fortified with superoxide at the μM level leads to recoveries of 95%The authors acknowledge financial support from projects PID2020- 113142RB-C21 and PID2020-113142RB-C22 and TED2021-129416AI00 funded by MCIN/AEI/10.13039/501100011033 and P2018/NMT4349 (TRANSNANOAVANSENS-CM) funded by the Comunidad Autonoma ´ de Madrid. We thank I. Ballesteros for the SEM measurements and Noemí Gonz´ alez Díaz from the Interdepartmental Research Service (SIDI) of the Universidad Autonoma ´ de Madrid for the XRD measurement

    Influence of Sleeping Patterns in Health and Academic Performance among University Students

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    Sleep problems in university students are important and have implications for health, quality of life, and academic performance. Using an ex post facto design, a total sample of 855 students (55.7% women) participated in the study. Sleep assessment was conducted using the Pittsburgh Sleep Quality Index, the Nightmare Frequency Scale, the Nightmare Proneness Scale, and the Composite Morningness Scale. Women show a higher risk [OR = 2.61] of presenting poor sleep quality (> 5 points on the PSQI) compared with men (p < 0.001). Similarly, women reported a greater frequency of nightmares (p < 0.001, d = 0.60), greater propensity for nightmares (p < 0.001, d = 0.70) and a higher score on Item-5h of the PSQI regarding nightmares (p < 0.001, d = 0.59). Women, compared with men, show higher risk [OR = 2.84] for a sleep disorder related to nightmares (p = 0.012). Women need more time to reach a state of alertness after getting up (p = .022), and there was an interaction between sex and the alertness factor when evaluating the subjective quality of sleep (p = 0.030). Women show worse sleep quality and a higher frequency and propensity for suffering nightmares. When considering the relationship between sleep quality and academic performance, it is observed that students with poor sleep quality obtain lower academic scores (M = 7.21, SD = 0.805) than those with good sleep quality (M = 7.32, SD = 0.685), an effect that reaches significance (t = 2.116, p = 0.035). Regarding the relationship between the categorized chronotype and academic performance, students with a morning chronotype achieve better academic results (M = 7.41, SD = 0.89) than their evening counterparts (M = 7.15, SD = 0.76), although these differences have a small effect size (d = 0.31)

    2D-ReS2 & diamond nanoparticles-based sensor for the simultaneous determination of sunset yellow and tartrazine in a multiple-pulse amperometry FIA system

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    We present a flow injection system with a multiple pulse amperometric detection (FIA-MPA)-based methodology for the simultaneous analysis of sunset yellow and tartrazine. As transducer, we have developed a novel electrochemical sensor based on the synergistic effect of ReS2 nanosheets and diamond nanoparticles (DNPs). Among several transition dichalcogenides for the sensor development, we have selected ReS2 nanosheets since it yields a better response towards both colourants. Scanning probe microscopy characterization shows that the surface sensor is composed by scattered and stacked ReS2 flakes and large aggregates of DNPs. With this system, the gap between the oxidation potential values of sunset yellow and tartrazine is wide enough to allow the simultaneous determination of both dyes. Under the optimum potential pulse conditions (0.8 and 1.2 V) during 250 ms, a flow rate of 3 mL/min and a volume injection of 250 μL, detection limits of 3.51 × 10− 7 M and 2.39 × 10− 7 M for sunset yellow and tartrazine, respectively, were obtained. This method exhibits good accuracy and precision with Er minor than 13% and RSD lower than 8% with a sampling frequency of 66 samples per hour. Pineapple jelly samples were analyzed by the standard addition method, obtaining 53.7 mg/kg and 29.0 mg/kg of sunset yellow and tartrazine, respectively. From the analysis of fortified samples, recoveries of 94% and 105% were obtainedThe authors acknowledge financial support from projects PID2020- 113142RB-C21 and PID2020-113142RB-C22 and TED2021-129416 AI00 funded by MCIN/AEI/10.13039/501100011033 and P2018/NMT4349 (TRANSNANOAVANSENS-CM) funded by the Comunidad Autonoma ´ de Madrid. We thank L. Chico for fruitful discussion

    Chemical, Thermal and Spectroscopic Methods to Assess Biodegradation of Winery-Distillery Wastes during Composting

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    The objective of this work was to study the co-composting process of wastes from the winery and distillery industry with animal manures, using the classical chemical methods traditionally used in composting studies together with advanced instrumental methods (thermal analysis, FT-IR and CPMAS 13C NMR techniques), to evaluate the development of the process and the quality of the end-products obtained. For this, three piles were elaborated by the turning composting system, using as raw materials winery-distillery wastes (grape marc and exhausted grape marc) and animal manures (cattle manure and poultry manure). The classical analytical methods showed a suitable development of the process in all the piles, but these techniques were ineffective to study the humification process during the composting of this type of materials. However, their combination with the advanced instrumental techniques clearly provided more information regarding the turnover of the organic matter pools during the composting process of these materials. Thermal analysis allowed to estimate the degradability of the remaining material and to assess qualitatively the rate of OM stabilization and recalcitrant C in the compost samples, based on the energy required to achieve the same mass losses. FT-IR spectra mainly showed variations between piles and time of sampling in the bands associated to complex organic compounds (mainly at 1420 and 1540 cm-1) and to nitrate and inorganic components (at 875 and 1384 cm-1, respectively), indicating composted material stability and maturity; while CPMAS 13C NMR provided semi-quantitatively partition of C compounds and structures during the process, being especially interesting their variation to evaluate the biotransformation of each C pool, especially in the comparison of recalcitrant C vs labile C pools, such as Alkyl /O-Alkyl ratio.This work was supported by a contract to MABM, Spanish Ministry of Economy and Competitiveness (Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (I+D+i) 2008-2011), co-funded by the EU through the Social Funds (contract reference PTQ-12-05655)

    Valorization of date palm (Phoenix dactylifera L.) pruning biomass by co-composting with urban and agri-food sludge

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    In the Mediterranean countries, there is an increasing production of date palm wastes (Phoenix dactylifera L.), not only due to the raising production of date palm fruits, but also derived from the maintenance of urban and peri-urban green areas, especially in those affected by red palm weevil (Rhynchophorus ferrugineus). The management of this increasing volume of green wastes usually concludes with a controlled disposal that implies an important loss of resources, in terms of organic matter, nutrients and energy. In addition, the rise of wastewater generation and the incentive of the wastewater treatment processes have derived in an increase of the amount of the sludge produced, which makes difficult its management. This work studies the feasibility of co-composting palm wastes with sludge from the urban and agri-food sectors as alternative treatment to manage these organic waste streams and to obtain added-value compost. For this, four mixtures (P1, P2, P3 and P4) were prepared using as main component palm leave waste (PL) mixed with different types of sludge. In the piles P1, P2 and P3, sewage sludge (SS) was used as co-composting agent, while agri-food sludge (AS) was used in P4. Throughout composting, the thermal profile of the composting piles was assessed, as were physical, chemical, physico-chemical and maturity parameters. In addition, the changes in water-soluble organic matter were assessed using chemical analytical methods and the excitation–emission matrix (EEM) fluorescence spectroscopy. The results obtained showed the viability of the co-composting process to obtain end-products with adequate maturity degree and physical characteristics for their potential use as substrates, except for the salt contents that can limit their use in some agricultural sectors.This work has been financed by the Spanish Ministry of Economy and Competitiveness and by European Regional Development Funds (ERDF, “Una manera de hacer Europa”), in the framework of the project “Development of new resources and bioproducts based on residues of palmaceous species oriented to carbon sequestration and mitigation strategies, Palmresource” (Project AGL2013-41612-R)

    Development of organic fertilizers from food market waste and urban gardening by composting in Ecuador

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    Currently, the management of urban waste streams in developing countries is not optimized yet, and in many cases these wastes are disposed untreated in open dumps. This fact causes serious environmental and health problems due to the presence of contaminants and pathogens. Frequently, the use of specific low-cost strategies reduces the total amount of wastes. These strategies are mainly associated to the identification, separate collection and composting of specific organic waste streams, such as vegetable and fruit refuses from food markets and urban gardening activities. Concretely, in the Chimborazo Region (Ecuador), more than 80% of municipal solid waste is dumped into environment due to the lack of an efficient waste management strategy. Therefore, the aim of this study was to develop a demonstration project at field scale in this region to evaluate the feasibility of implanting the composting technology not only for the management of the organic waste fluxes from food market and gardening activities to be scaled-up in other developing regions, but also to obtain an end-product with a commercial value as organic fertilizer. Three co-composting mixtures were prepared using market wastes mixed with pruning of trees and ornamental palms as bulking agents. Two piles were created using different proportions of market waste and prunings of trees and ornamental palms: pile 1 (50:33:17) with a C/N ratio 25; pile 2: (60:30:10) with C/N ratio 24 and pile 3 (75:0:25) with C/N ratio 33), prepared with market waste and prunings of ornamental palm. Throughout the process, the temperature of the mixtures was monitored and organic matter evolution was determined using thermogravimetric and chemical techniques. Additionally, physico-chemical, chemical and agronomic parameters were determined to evaluate compost quality. The results obtained indicated that all the piles showed a suitable development of the composting process, with a significant organic matter decomposition, reached in a shorter period of time in pile 3. At the end of the process, all the composts showed absence of phytotoxicity and suitable agronomic properties for their use as organic fertilizers. This reflects the viability of the proposed alternative to be scaled-up in developing areas, not only to manage and recycle urban waste fluxes, but also to obtain organic fertilizers, including added value in economic terms related to nutrient contents.This work was supported by a PhD scholarship to JJS of the National Secretary of Higher Education, Science, Technology and Innovation SENESCYT of Ecuador and it was also developed in the framework of the project of the Spanish Ministry of Economy and Competitiveness co-funded by the EU through the Social Funds (ref. AGL2013-41612-R)

    Evaluation of the interrelated effects of slaughtering, drying, and defatting methods on the composition and properties of black soldier fly (Hermetia illucens) larvae fat

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    The interrelated effect of different slaughtering, drying and defatting methods of black soldier fly larvae (BSFL) on the lipid composition and properties of the fat was studied. Blanching and freezing were compared as slaughtering methods, oven or freeze-drying as drying methods, and mechanical pressing or supercritical fluid extraction (SFE) as defatting methods. The different modes of slaughtering, drying, and defatting, along with both binary and ternary interactions caused significant effects on processes yields, lipid composition, moisture content and thermal properties. Thus, considering the defatting degree and the yield in total valued products (defatted meal plus fat), the combination of blanching, freeze-drying plus mechanical pressing was the worst option (51.2% and 87.5%, respectively). In contrast, the other combinations demonstrated better and comparable efficiency, although SFE is preferable for defatting (83.2% and 96.9%, respectively). The content of major fatty acids (lauric, palmitic and myristic acids) was significantly affected by the BSFL treatments, although with unsignificant impact on the total saturated fatty acids content. To preserve the integrity of the fat, the combination of blanching and oven-drying was preferred, as non-thermal methods of slaughtering and drying caused intense lipolysis, releasing free fatty acids (FFA) in the range of 18.6–23.5%. To achieve the lowest moisture content in the fats (≤0.1%), oven-drying with mechanical pressing were desired, regardless of the slaughtering method; while values > 1% were reached for freezing, freeze-drying and SFE. Both differences in FFA and moisture contents caused different thermal behaviors in the samples. Specially, the melting temperature was lower for samples with higher FFA and moisture contents, with a notable difference when freezing, freeze-drying and SFE were combined (14.5 ◦C vs 30.6 ◦C, as the mean value for the rest of samples). The different modes of processing did not affect the minor lipid compounds. Therefore, the modes employed for slaughtering, drying, and defatting of BSFL determine, either individually or in combination, the process yields, composition, and properties of the fatThis research was funded by the Spanish National Plans of Aquaculture of the Ministry of Agriculture, Fisheries and Food, project ACUINSECT (Optimization of insect flours as sustainable ingredient for aquaculture feed) with the support of the European Maritime and Fisheries Fund (FEMP
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