Hybrid Sepic-Ćuk DC-DC Converter Associated to a SRM Drive for a Solar PV Powered Water Pumping System

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2019 do Instituto Politécnico de Lisboa. Código de referência IPL/2019/SOLARPUMP_ISELThe present paper describes a solar photovoltaic (SPV) powered water pumping system employing a switched reluctance motor (SRM) and a merged Sepic-Ćuk DC-DC converter. The proposed solution was designed to use efficiently the available solar energy in order to supply water pumping systems. Solutions of this kind assume a special importance in the current scenario of natural and renewable resources optimization. The proposed DC-DC converter operates in continuous conduction mode (CCM), which combined with a maximum power point tracking (MPPT) controller, helps to optimize the power of the solar photovoltaic panel (SPV). The proposed DC-DC topology is characterized by high voltage static gain when compared with the classical boost topology and reduced voltage stress across the power switch and diodes. Several simulation and experimental results are presented in order to confirm the characteristics of the proposed solution for water pumping systems.info:eu-repo/semantics/publishedVersio

Erratum: Moreira, J., et al., Spin-Coated Polysaccharide-Based Multilayered Freestanding Films with Adhesive and Bioactive Moieties. Molecules 2020, 25, 840

Erratum: Moreira, J., et al., Spin-Coated Polysaccharide-Based Multilayered Freestanding Films with Adhesive and Bioactive Moieties. Molecules 2020, 25, 840. DOI: 10.3390/molecules25040840The authors wish to make changes to the published paper 11 j. 1. UV-Vis Analysis of Catechol-Modified Polymers In the original manuscript theie is a mistake concerning the word "Wavenumber" in the X-Coordinate in Figure 1. Tile corrected word is "Wavelength". Tlx- A uthors also wish to change mg«mL-l to mg ml-1 in the legend of Figure l;see corrected Figure 1 below. (Figure Presented).(undefined

Double-layer force suppression between charged microspheres

In this paper we propose a protocol to suppress double-layer forces between two microspheres immersed in a dielectric medium, being one microsphere metallic at a controlled potential ψ M and the other a charged one either metallic or dielectric. The approach is valid for a wide range of distances between them. We show that, for a given distance between the two microspheres, the double-layer force can be totally suppressed by simply tuning ψ M up to values dictated by the linearized Poisson-Boltzmann equation. Our key finding is that such values can be substantially different from the ones predicted by the commonly used proximity force approximation, also known as the Derjaguin approximation, even in situations where the latter is expected to be accurate. The proposed procedure can be used to suppress the double-layer interaction in force spectroscopy experiments, thus paving the way for measurements of other surface interactions, such as Casimir dispersion forces

Pre-selection of fibroblasts subsets prompt prevascularization of tissue engineered skin analogues

The papillary and reticular dermis harbors phenotypically distinct fibroblasts, whose functions such as maintenance of skin's microvasculature are also distinct. Thus, we hypothesized that pre-selection of the subpopulations of fibroblasts would benefit the generation of skin tissue engineered (TE) constructs, promoting their prevascularization in vitro. We first isolated papillary and reticular fibroblasts using fluorescence-activated cell sorting and studied the effect of their secretome and extracellular matrix (ECM) on human dermal microvascular endothelial cell (hDMEC) organization. Subsequently, we developed a bilayered 3D polymeric structure with distinct layer-associated features to house the subpopulations of fibroblasts, to generate a skin analogue. Both papillary and reticular fibroblasts were able to stimulate capillary-like network formation in a Matrigel assay. However, the secretome of the two subpopulations was substantially different, being enriched in VEGF, IGF-1, and Angio-1 in the case of papillary fibroblasts and in HGF and FGF-2 for the reticular subset. In addition, the fibroblast subpopulations deposited varied levels of ECM proteins, more collagen I and laminin was produced by the reticular subset, but these differences did not impact hDMEC organization. Vessel-like structures with lumens were observed earlier in the 3D skin analogue prepared with the sorted fibroblasts, although ECM deposition was not affected by the cell's pre-selection. Moreover, a more differentiated epidermal layer was obtained in the skin analogue formed by the sorted fibroblasts, confirming that its whole structure was not affected. Overall, we provide evidence that pre-selection of papillary and reticular fibroblasts is relevant for promoting the in vitro prevascularization of skin TE constructs.The authors would like to acknowledge the financial support from the Consolidator Grant “ECM_INK” (ERC-2016- COG-726061), to the FSE/POCH (Fundo Social Europeu através do Programa Operacional do Capital Humano) under the scope of the PD/169/2013, NORTE-08-5369-FSE-000037 (H.R. M.)

Using simulation to model the logistic operations of a company of the cement industry

This paper presents a discrete-event simulation model to study the logistics operations involved in a plant of the cement industry, aligned with a real project developed in partnership between Cachapuz (a company that provides international weighing solutions) and the University of Minho. The purpose of this work consists in using simulation to model several activities, involving weighing, loading and unloading of raw materials, regardless of the type of industry, e.g. cement, tomato, cereals. Thus, this paper documents the work conducted to apply the developed simulation model in a case study of the cement industry. After validating the model, a set of simulation experiments were conducted, which allowed to estimate the maximum capacity of the plant and the impact in the performance of the plant, of the arrival of a cargo vessel. In this regard, it was found that in the case study in question, it is not possible to unload all the cargo from the vessel in a working day - around 3 working days would be required. Further conclusions and future work are discussed in the last section.- (undefined

Differences in the phenolic composition and nutraceutical properties of freeze dried and oven-dried wild and domesticated samples of Sanguisorba minor Scop

Recent studies have dealt about the phenolic compounds and the nutraceutical properties of Sanguisorba minor Scop and about the possibility of their domestication to standardise the plant production. However, it is also known that the storage conditions can affect the bioactive compounds present in plants. Thus, wild (W) and domesticated (F1, F2, F3) S. minor samples were exposed to different drying methods (oven-drying at 60 °C until constant weight named OD or freeze-drying until constant weight named FD) and studied for their content in phenolic compounds, antioxidant, antimicrobial, cytotoxic and anti-inflammatory properties. In general, OD samples showed the highest nutraceutical properties and the highest content in phenolic compounds. The most abundant phenolic compounds in both drying methods were kaempferol-3-O-glucoside and caffeoyl ester, with some differences between wild and domesticated samples. Wild samples showed higher antimicrobial and cytotoxic activity than domesticated ones, except for the OD F3 and FD F2 samples that reported cytotoxicity against HeLa cells. This study provides important information to choose the most adequate methodology to retain phenolic compounds and nutraceutical properties of S. minor species. Further researches are necessary to standardise the domestication of the studied wild species and verify the highest efficiency of the OD method.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2020). L. Barros and C. Calhelha also thank the national funding by FCT – Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract for their contracts, and Sandrina A. Heleno thanks to the national funding by FCT, P.I., through the individual scientific employment program-contract. The authors are also grateful to FEDER-Interreg España-Portugal programme for financial support through the project TRANSCoLAB 0612_TRANS_CO_LAB_2_P and to European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project Norte-01- 0145-FEDER-000042: GreenHealth.info:eu-repo/semantics/publishedVersio

Design and Properties of Novel Substituted Borosilicate Bioactive Glasses and Their Glass-Ceramic Derivatives

Three novel borosilicate bioactive glasses (BBGs) of general formula of 0.05Na2O·0.35x·0.20B2O3·0.40SiO2 (molar ratio, where x = MgO or CaO or SrO) were prepared and used to investigate the effect of crystallization on their properties including cytotoxicity. The three postmelt compositions were determined using X-ray fluorescence spectroscopy, and crystallization events were studied using differential thermal analysis and X-ray diffraction. This information was used to determine heat treatments to prepare glass-ceramics by controlled crystallization. X-ray diffraction analysis and Fourier transform infrared spectroscopy showed that, after higher heat treatment temperatures (800–900 °C), borosilicate bioactive glass-ceramics (BBGCs) contained mainly borate and silicate crystalline phases. Specifically, BBG-Mg, BBG-Ca, and BBG-Sr glass-ceramics detected the presence of magnesium silicate-Mg2(SiO3)2 and magnesium borate-Mg2B2O5; wollastonite-2M-CaSiO3 and calcium borate-Ca(BO2)2; and strontium silicate-SrSiO3 and strontium borate-Sr2B2O5, respectively. In vitro cytotoxicity tests were performed using the mouse fibroblast cell line (L929). Glass and glass ceramic at concentrations lower than 50 mg/mL did not exhibit any level of cytotoxicity when compared with the control. However, quantitative evaluation indicated that greater cell growth occurred in the presence of materials with crystalline phases. Control of BBGs crystallization may therefore be used to influence the biocompatibility of these glass-ceramic systems

ANÁLISE TERMOMECÂNICA DE ESTRUTURAS DE AÇO VIA ACOPLAMENTO MCD/MRPR

Quando expostos à temperatura elevada, os elementos estruturais têm sua capacidade resistente comprometida, pois as características físicas e de resistência dos materiais empregados nas estruturas se deterioram com o aumento de temperatura. Nesse contexto, o presente trabalho tem como objetivo apresentar um novo módulo computacional,denominado aqui CS-ASA/FSA, capaz de realizar a análise numérica de estruturas de aço sujeitas à temperaturas elevadas. Esse módulo utiliza o Método dos Elementos Finitos (MEF) e a análise inelástica é baseada no Método da Rótula Plástica Refinado (MRPR) acoplado ao Método da Compatibilidade de Deformações (MCD). Esse último método foi adotado para avaliar tanto a capacidade resistente da seção transversal, quanto as rigidezes axial e à flexão de estruturas de aço sob elevadas temperaturas. A construção da relação momentocurvatura se torna essencial para tal avaliação. Por fim, os resultados obtidos são comparados aos numéricos e experimentais encontrados na literatura