Stochastic harmonic emission model of aggregate residential customers

Harmonic propagation studies of public distribution networks require accurate models of aggregate residential customers (groups of customers) that simulate the harmonic emission of the multitude of household appliances in the network. Most of the present models were developed with the component-based approach, where models of individual household appliances are combined to build the model of multiple customers. This approach requires high amount of input data, like models of individual household appliances and detail information of customer behavior and device composition, which is usually not easy to acquire. However, with the increasing number of PQ-analyzers in the networks, the measurement-based approach is now more and more considered for the modeling of aggregate customers. The measurement-based approach uses measurements of the network in combination with top-down methodologies to obtain models of the aggregate customers. Compared to the component-based approach it has several advantages, like inherent consideration of the real operating changes of the individual household appliances, variation of customer behavior, effect of line impedances, cancellation and attenuation effects, etc. This thesis presents the development of a time-series stochastic model of the low-order harmonic emission of aggregate residential customers based on a top-down measurement-based approach. The model represents the daily variation of the harmonic magnitudes and phase angles. Besides, the model includes the representation of the harmonic unbalances, which is of great importance for the proper analysis of harmonic propagation in medium-voltage networks. The model is parametrized for German networks, but the methodology can be applied to find the models of other regions or countries

The enzymatic determination of glucose in carbonated beverages: a useful tool for the undergraduate students to learn the basis of enzymatic analysis and the comparison of two analytical methods

The importance of enzymatic analysis in biochemistry, clinical chemistry and food chemistry is undoubted. The course "Applied Biochemistry" in our Faculty is aimed to undergraduate students of Chemistry and Biochemistry. In this subject, the principles and applications of enzymatic analysis are presented to the students, who receive a theoretical introductory lecture in the classroom before they carry out an experiment that should be feasible to be solved in a short laboratory period. The experimental protocol here presented, based on the enzymatic determination of glucose in carbonated beverages, has been implemented at the University of Málaga and it has been optimized according to the students’ results and commentaries along the last years. It aims to illustrate basic issues relating enzymatic analysis, including its potential application to food chemistry. Although there are several enzymatic methods that can be used for the determination of glucose, we selected the one based on the coupled reactions of glucose oxidase (GOD; EC 1.1.3.4.) and peroxidase (POD; EC 1.11.1.7.) because the kinetic constants of glucose oxidase allow the mentioned enzymatic reactions to be used in both, the end point and the kinetic enzymatic analysis methods. In this way, data for two different protocols for the determination of glucose concentration are obtained by the students from a single reaction mixture. Students construct a calibration curve for each method using a glucose standard solution, and use them to determine the glucose concentration in the problem solutions. The inclusion of replicate samples in the determination of the glucose concentration of an “ideal problem” (glucose in purified water) is used to illustrate the principles of statistics in the lab, and comparison with the “real value” allows an estimation of the accuracy of each method. The evaluation of glucose concentration in four carbonated beverages: coloured coke and uncoloured tonic sodas (regular or sugarless in both cases) makes student to recognise the appearance of interferences that should be either avoided or eliminated. Since all samples are analysed by means of end-point and kinetic methods, students can discuss the applicability of each method to these specific analytical problems. They are also encouraged to compare both analytical methods in terms of sensitivity, selectivity, accuracy, and time consumed. Chemistry and Biochemistry undergraduate students having performed this experiment in our laboratories have found it formative, interesting and challenging.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A practice project to prevent the cookbook model as modus operandi for biochemistry laboratory learning

Laboratory learning is a crucial component of chemistry and biochemistry instruction and should be conceived as a way to develop students’ reasoning, technical or practical skills, introducing them into the scientific method principles. Nevertheless, the heavily criticized “expository instruction style”, characterized by a cookbook nature, is still the most widespread style of laboratory instruction in our universities. Alternative learning styles based in the inquiry, discovery and problem-based pedagogical approaches, have been reported to promote students’ problem solving skills, critical thought and self-confidence development. We are currently involved in the Educative Innovation Project PIE17-065, funded by University of Malaga, aimed to improve the teaching practice of Biochemistry laboratory to undergraduate students. Based on an enzymatic analysis of glucose in soft-drinks we have developed a laboratory protocol as a part of a full practice project where students must work before and after the lab session, in order to prevent the cookbook model as modus operandi, therefore preventing the situation where the students get a first glimpse of the experiment protocol whereas they put on their lab coat. The learning activities have been designed to move our students from the passive role that characterizes the step-by-step procedures, to an active and critical attitude that starts before and remains after their laboratory session, also minimizing time, space, and equipment resources. Our results have shown that this experiment has improved the learning of both, future biochemists and chemists, which showed a very positive perception of the whole practical project.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. PIE 17-06

One-Step Preparation of Large Area Films of Oriented MoS2 Nanoparticles on Multilayer Graphene and Its Electrocatalytic Activity for Hydrogen Evolution

[EN] MoS2 is a promising material to replace Pt-based catalysts for the hydrogen evolution reaction (HER), due to its excellent stability and high activity. In this work, MoS2 nanoparticles supported on graphitic carbon (about 20 nm) with a preferential 002 facet orientation have been prepared by pyrolysis of alginic acid films on quartz containing adsorbed (NH4)(2)MoS4 at 900 degrees C under Ar atmosphere. Although some variation of the electrocatalytic activity has been observed from batch to batch, the MoS2 sample exhibited activity for HER (a potential onset between 0.2 and 0.3 V vs. SCE), depending on the concentrations of (NH4)(2)MoS4 precursor used in the preparation process. The loading and particle size of MoS2, which correlate with the amount of exposed active sites in the sample, are the main factors influencing the electrocatalytic activity.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69513-CO2-R1) and Generalidad Valenciana (Prometeo 2013/014) is gratefully acknowledged. Jinbao He thanks the Chinese Scholarship Council for supporting his PhD studies.He, J.; Fernández-Blanco, AC.; Primo Arnau, AM.; García Gómez, H. (2018). One-Step Preparation of Large Area Films of Oriented MoS2 Nanoparticles on Multilayer Graphene and Its Electrocatalytic Activity for Hydrogen Evolution. Materials. 11(1):1-11. https://doi.org/10.3390/ma11010168S111111Chhowalla, M., Shin, H. S., Eda, G., Li, L.-J., Loh, K. P., & Zhang, H. (2013). The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nature Chemistry, 5(4), 263-275. doi:10.1038/nchem.1589Lukowski, M. A., Daniel, A. S., Meng, F., Forticaux, A., Li, L., & Jin, S. (2013). Enhanced Hydrogen Evolution Catalysis from Chemically Exfoliated Metallic MoS2 Nanosheets. Journal of the American Chemical Society, 135(28), 10274-10277. doi:10.1021/ja404523sVoiry, D., Yamaguchi, H., Li, J., Silva, R., Alves, D. C. B., Fujita, T., … Chhowalla, M. (2013). Enhanced catalytic activity in strained chemically exfoliated WS2 nanosheets for hydrogen evolution. Nature Materials, 12(9), 850-855. doi:10.1038/nmat3700Li, Y., Wang, H., Xie, L., Liang, Y., Hong, G., & Dai, H. (2011). MoS2Nanoparticles Grown on Graphene: An Advanced Catalyst for the Hydrogen Evolution Reaction. Journal of the American Chemical Society, 133(19), 7296-7299. doi:10.1021/ja201269bLatorre-Sánchez, M., Esteve-Adell, I., Primo, A., & García, H. (2015). Innovative preparation of MoS2–graphene heterostructures based on alginate containing (NH4)2MoS4 and their photocatalytic activity for H2 generation. Carbon, 81, 587-596. doi:10.1016/j.carbon.2014.09.093Primo, A., Sánchez, E., Delgado, J. M., & García, H. (2014). High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan. Carbon, 68, 777-783. doi:10.1016/j.carbon.2013.11.068Mateo, D., Esteve-Adell, I., Albero, J., Royo, J. F. S., Primo, A., & Garcia, H. (2016). 111 oriented gold nanoplatelets on multilayer graphene as visible light photocatalyst for overall water splitting. Nature Communications, 7(1). doi:10.1038/ncomms11819Primo, A., Esteve-Adell, I., Blandez, J. F., Dhakshinamoorthy, A., Álvaro, M., Candu, N., … García, H. (2015). High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film. Nature Communications, 6(1). doi:10.1038/ncomms9561Primo, A., Esteve-Adell, I., Coman, S. N., Candu, N., Parvulescu, V. I., & Garcia, H. (2015). One-Step Pyrolysis Preparation of 1.1.1 Oriented Gold Nanoplatelets Supported on Graphene and Six Orders of Magnitude Enhancement of the Resulting Catalytic Activity. Angewandte Chemie International Edition, 55(2), 607-612. doi:10.1002/anie.201508908Primo, A., Atienzar, P., Sanchez, E., Delgado, J. M., & García, H. (2012). From biomass wastes to large-area, high-quality, N-doped graphene: catalyst-free carbonization of chitosan coatings on arbitrary substrates. Chemical Communications, 48(74), 9254. doi:10.1039/c2cc34978gPedraza, F., Cruz-Reyes, J., Acosta, D., Yanez, M. J., Avalos-Borja, M., & Fuentes, S. (1993). Journal of Physics: Condensed Matter, 5(33A), A219-A220. doi:10.1088/0953-8984/5/33a/069Li, H., Zhang, Q., Yap, C. C. R., Tay, B. K., Edwin, T. H. T., Olivier, A., & Baillargeat, D. (2012). From Bulk to Monolayer MoS2: Evolution of Raman Scattering. Advanced Functional Materials, 22(7), 1385-1390. doi:10.1002/adfm.201102111Yan, Y., Ge, X., Liu, Z., Wang, J.-Y., Lee, J.-M., & Wang, X. (2013). Facile synthesis of low crystalline MoS2 nanosheet-coated CNTs for enhanced hydrogen evolution reaction. Nanoscale, 5(17), 7768. doi:10.1039/c3nr02994hLi, H., Tsai, C., Koh, A. L., Cai, L., Contryman, A. W., Fragapane, A. H., … Zheng, X. (2015). Activating and optimizing MoS2 basal planes for hydrogen evolution through the formation of strained sulphur vacancies. Nature Materials, 15(1), 48-53. doi:10.1038/nmat4465Tsai, C., Chan, K., Nørskov, J. K., & Abild-Pedersen, F. (2015). Theoretical insights into the hydrogen evolution activity of layered transition metal dichalcogenides. Surface Science, 640, 133-140. doi:10.1016/j.susc.2015.01.01

The Wound-Healing Portal Hypertensive Response

Portal hypertensive inflammation is associated with chronic liver diseases. The three successive and overlapping systemic inflammatory phenotypes, i.e., neurogenic, immune, and endocrine, which characterize the wound-healing response, are expressed by the portal venous system upon liver injury. The diverse functions of hepatic stellate cells in homeostasis and inflammation indicate the versatile nature of these mesenchymal-derived cells, which could adopt numerous phenotypes according to the interstitial microenvironmental characteristics. Consequently, these inflammatory phenotypes could represent the reexpression of two extra-embryonic functional axis, i.e., coelomic-amniotic and trophoblastic-vitelline, whose coupling in the portal system would induce a gastrulation-related phenotype. Therefore, hepatic stellate cells and liver-specific mesenchymal cells could recapitulate and couple these abovementioned extra-embryonic phenotypes during portal hypertension. These hepatic cellular population, thanks to their potential ability to integrate and reexpress functions showing analogies to extra-embryonic functions, display characteristics of stem/progenitor cells. In this way, during the development of portal hypertension, hepatic stellate cells not only could reexpress extra-embryonic functions, but also could adapt themselves in order to induce a gastrulation-related process in the space of Disse. Hence, by understanding the ontogenic interactions between hepatic stellate cells and the host inflammatory response in portal hypertension, it is possible to design effective therapeutic and prophylactic strategies to avoid or reverse wound-like hypertensive response

Learning contract, co-operative and flipped learning as useful tools for studying metabolism

Es el Abstract de una comunicación a un congreso internacional sobre educaciónUndergraduate students in Biology identify Metabolic Biochemistry as a particularly difficult subject. This is due to the fact that students need to interconnect properly all the contents of its syllabus throughout their study of the subject in order to get a global insight of the complex regulatory features controlling metabolic pathways within the metabolic network under different physiologic and pathologic conditions, as well as metabolism as a whole. Due to these objective difficulties, a high percentage of our students face the study of this subject as a very hard task beyond their forces and capacities. This perception leads to high rates of premature dropout. In previous years, less than 40% of all the registered students attended the examinations of Metabolic Biochemistry (a subject in the second year of the Degree of Biology at our University). Even worse, less than 25% of our students passed the exams. From the academic year 2015/16 on, we are developing innovative teaching projects (PIE15-163 and PIE17-145, funded by University of Malaga) aimed to increase our student loyalty to the subject (and hence to increase their attendance to exams) and to help them to learn more effectively metabolism and its regulation. These innovative teaching projects are based on the use of several powerful tools: a learning contract and problem-based learning within the framework of group tasks promoting an actual collaborative learning in a flipped classroom. The present communication will show the implementation of the PIE15-163 and PIE17-145 projects and some results obtained from them.This work was supported by Malaga University funds granted to the educational innovation project PIE17-145. The attendance to the END2018 International Conference on Education and New Developments (June 2018, Budapest, Hungary) has received a grant from "I Plan Propio Integral de Docencia. Universidad de Málaga"]

Partilha da álea no contrato de resseguro

Na presente dissertação estuda-se o princípio da partilha da álea, corolário da conexão funcional estabelecida entre o contrato de resseguro e o contrato de seguro. Inicia-se pelo exame de pontos com os quais a partilha da álea se liga direta ou indiretamente, tais como a estrutura e da função do contrato de resseguro, e a compreensão de risco, juridicamente considerado, pontos essenciais para compreender o contrato de resseguro e o que será objeto de partilha. Busca-se, ao fim, estabelecer a noção conceitual de tal preceito e os critérios relacionados ao limite da sua atuação, como forma de contribuir a sua compreensão e correta utilização no cenário jurídico e econômico brasileiro, dada a recente abertura do mercado ressecuritário.The main subject of the present thesis is the principle of following the fortunes, corollary of the bond between the insurance and the reinsurance contracts. The study begins by examining points to whom following the fortunes is directly or indirectly connected - as such function and structure of the reinsurance contract, and the judicial comprehensiveness of the risk involved; points necessary to understand both the reinsurance contract and the object that is being shared through it. The study aims, in the end, to establish an undertanding of such concept, the principle mentioned above, including the criteria on the realm of its application, in order to bring some clarification to its juridical and economical usage in Brazil, necessary after the recent reinsurance market changes

Motivational drivers to choose worker cooperatives as an entrepreneurial alternative: evidence from Spain

Worker cooperatives as an entrepreneurial activity that values collective benefits have raised increasing interest in recent years. This prioritisation clearly distinguishes this business model from other entrepreneurial forms. Nevertheless, entrepreneurship research to date has rarely focused on worker cooperatives. This study draws on this gap by examining the main factors decisive for people preferring this business model. The results suggest five factors that can act as drivers for improving entrepreneurial creation through worker cooperatives and conforming to an entrepreneurship path aimed at improving social cohesion. These factors are related to several key points: cooperative principles and the governance model of these organisations; the perception of this model as especially suited for favouring equality; the individual’s social orientation; and the influence of external aids provided to the constitution of worker cooperatives. The findings also suggest the need for effective public policies that favour the cooperative model since it promotes a more responsive and sustainable economic growth

Future work on harmonics : some expert opinions part I : wind and solar power

A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. The results of this discussion are summarized in this paper and some of the issues are discussed in more detail in this paper and in its companion paper. This paper discusses emission from wind and solar power as well as advantages and disadvantages of active and passive filters