Viscous microcapsules as microbioreactors to study mesenchymal stem/stromal cells osteolineage commitment

It is essential to design a multifunctional well-controlled platform to transfermechanical cues to the cells in different magnitudes. This study introduces aplatform, a miniaturized bioreactor, which enables to study the effect of shearstress in microsized compartmentalized structures. In this system, thewell-established cell encapsulation system of liquefied capsules (LCs) is usedas microbioreactors in which the encapsulated cells are exposed to variablecore viscosities to experience different mechanical forces under a 3D dynamicculture. The LC technology is joined with electrospraying to produce suchmicrobioreactors at high rates, thus allowing the application of microcapsulesfor high-throughput screening. Using this platform for osteogenicdifferentiation as an example, shows that microbioreactors with higher coreviscosity which produce higher shear stress lead to significantly higherosteogenic characteristics. Moreover, in this system the forces experienced bycells in each LC are simulated by computational modeling. The maximum wallshear stress applied to the cells inside the bioreactor with low, and high coreviscosity environment is estimated to be 297 and 1367 mPa, respectively, forthe experimental setup employed. This work outlines the potential of LCmicrobioreactors as a reliable in vitro customizable platform with a wide rangeof applications.publishe

Isolated Taylor Bubbles in Co-Current with Shear Thinning CMC Solutions in Microchannels—A Numerical Study

Slug flow is a multiphase flow pattern characterized by the occurrence of long gas bubbles (Taylor bubbles) separated by liquid slugs. This multiphase flow regime is present in many and diversified natural and industrial processes, at macro and microscales, such as in eruption of volcanic magmas, oil recovery from pre-salt regions, micro heat exchangers, and small-sized refrigerating systems. Previous studies in the literature have been mostly focused on tubular gas bubbles flowing in Newtonian liquids. In this work, results from several numerical simulations of tubular gas bubbles flowing in a shear thinning liquid in microchannels are reported. To simulate the shear thinning behavior, carboxymethylcellulose (CMC) solutions with different concentrations were considered. The results are compared with data from bubbles flowing in Newtonian liquids in identical geometric and dynamic conditions. The numerical work was carried out in computational fluid dynamics (CFD) package Ansys Fluent (release 16.2.0) employing the volume of fluid (VOF) methodology to track the volume fraction of each phase and the continuum surface force (CSF) model to insert the surface tension effects. The flow patterns, the viscosity distribution in the liquid, the liquid film thickness between the bubble and the wall, and the bubbles shape are analyzed for a wide range of shear rates. In general, the flow patterns are similar to those in Newtonian liquids, but in the film, where a high viscosity region is observed, the thickness is smaller. Bubble velocities are smaller for the non-Newtonian cases.</jats:p

Efeito dos modos de transferência e da composição de gás de protecção na emissão de partículas ultrafinas na soldadura MAG de aços

The present study aims to characterize ultrafine particles emitted during gas metal arc welding of mild steel and stainless steel, using different shielding gas mixtures, and to evaluate the effect of metal transfer modes, controlled by both processing parameters and shielding gas composition, on the quantity and morphology of the ultrafine particles. It was found that the amount of emitted ultrafine particles (measured by particle number and alveolar deposited surface area) are clearly dependent from the main welding parameters, namely the current intensity and the heat input of the Welding process. The emission of airborne ultrafine particles increases with the current intensity as fume formation rate does. When comparing the shielding gas mixtures, higher emissions were observed for more oxidizing mixtures, that is, with higher CO2 content, which means that these mixtures originate higher concentrations of ultrafine particles (as measured by number of particles. by cubic centimeter of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more hazardous condition regarding welders exposure

Computation of a three-dimensional flow in a square microchannel: a comparison between a particle method and a finite volume method

Traditional grid-based numerical methods, such as finite volume method (FVM), are not suitable to simulate multiphase biofluids (such as blood) at the microscale level. Alternatively, meshfree Lagrangian methods can deal with two or more finely dispersed phases moving relatively to each other. The Moving Particle Semi-Implicit Method (MPS), used in this study, is a deterministic particle method based on a Lagrangian technique to simulate incompressible flows. The advantages of particle methods over traditional grid-based numerical methods have motivated several researchers to implement them into a wide range of studies in computational biomicrofluidics. The main aim of this paper is to evaluate the accuracy of the MPS method by comparing it with numerical simulations performed by an FVM. Hence, simulations of a Newtonian fluid flowing through a constriction were performed for both methods. For the MPS, a section of the channel of 3011.511.5 m was simulated using periodic boundary conditions. The obtained results have provided indications that, if the initial particle distance is sufficiently small, the MPS method can calculate accurately velocity profiles in the proposed channel.The authors acknowledge the financial support provided by PTDC/SAU-ENB/116929/2010 and EXPL/EMSSIS/2215/2013 from FCT (Science and Technology Foundation), COMPETE, QREN and European Union (FEDER). D. Bento acknowledge the financial support provided by SFRH/BD/91192/2012 from FCT (Science and Technology Foundation), COMPETE, QREN and European Union (FEDER). The authors are also very grateful to Dr. Alberto Gambaruto (Bristol University) for helpful explanations and suggestions regarding the MPS method.info:eu-repo/semantics/publishedVersio

Analytical methodologies for the determination of biogenic amines in wines: an overview of the recent trends

Biogenic amines are naturally present in grapes or can occur during the vinification and aging processes, essentially due to the microorganism’s activity. When present in wines in high amount, biogenic amines may cause not only organoleptic defects but also adverse effects in sensitive human individuals, namely due to the toxicity of histamine, tyramine and putrescine. Even though there are no legal limits for the concentration of biogenic amines in wines, some European countries only recommend maximum limits for histamine. In this sense, biogenic amines in wines have been widely studied. The determination of amines in wines is commonly achieved by liquid chromatography, using derivatization reagents in order to promote its separation and detection. In alternative, other promising methodologies have been developed using capillary electrophoresis or biosensors, revealing lower costs and faster results, without needing a derivatization step. Nowadays, it is still a challenge to develop faster and inexpensive techniques or methodologies to apply in the wine industry. Thus, this review will be focused on the studies published in the last decade that involves the determination of biogenic amines in wines, highlighting the novelty, improvement and optimization of the analytical methods. The sample preparation procedures (such as derivatization reagents), the analytical methodologies and the new trends being followed by the wine industry are also described and discussed.info:eu-repo/semantics/publishedVersio

A review on power electronic converters for modular BMS with active balancing

Electric vehicles (EVs) are becoming increasingly popular due to their low emissions, energy efficiency, and reduced reliance on fossil fuels. One of the most critical components in an EV is the energy storage and management system, which requires compactness, lightweight, high efficiency, and superior build quality. Active cell equalization circuits such as those used in battery management systems (BMS) have been developed to balance the voltage and state of charge (SoC) of individual cells, ensuring the safety and reliability of the energy storage system. The use of these types of equalization circuits offers several benefits including improved battery performance, extended battery life, and enhanced safety, which are essential for the successful adoption of EVs. This paper provides a comprehensive overview of the research works related to active cell equalization circuits. This review highlights the important aspects, advantages and disadvantages, and specifications.This work was supported by FCT—Fundação para a Ciência e Tecnologia, within the R&D Units Project Scope UIDB/00319/2020. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018, granted by the Portuguese FCT foundation

Airborne PM Impact on Health, Overview of Variables, and Key Factors to Decision Making in Air Quality

This chapter intends to contribute to the understanding of the multiple aspects related to particulate matter (PM) in an air urban environment, in particular, regarding its impact on human health. A general overview of variables and key factors is presented to identify, relate, and understand the diverse and multidisciplinary variables that contribute to PM concentration in urban environments associated with health impacts. This relation is difficult to quantify, given the numerous variables that are interlinked due to the multidisciplinary aspects involved. Our aim is to identify the main multidisciplinary aspects, namely, meteorology, urban geometry, buildings, roads and footpaths, road traffic, industries, air concentration measurements, and health. The main strategic aspects for decision making related to airborne PM impact on health are also discussed

Determination of airborne nanoparticles from welding operations

The aim of this study is to assess the levels of airborne ultrafine particles emitted in welding processes (tungsten inert gas [TIG], metal active gas [MAG] of carbon steel, and friction stir welding [FSW] of aluminum) in terms of deposited area in pulmonary alveolar tract using a nanoparticle surface area monitor (NSAM) analyzer. The obtained results showed the dependence of process parameters on emitted ultrafine particles and demonstrated the presence of ultrafine particles compared to background levels. Data indicated that the process that resulted in the lowest levels of alveolar deposited surface area (ADSA) was FSW, followed by TIG and MAG. However, all tested processes resulted in significant concentrations of ultrafine particles being deposited in humans lungs of exposed workers

Comparação das capturas de Antaxius spinibrachius (Orthoptera: Tettigoniidae) em armadilhas iscadas com feromona sexual deThaumetopoea pityocampa Schiff. e armadilhas sem feromona num povoamento de Pinus pinaster Ait. em Varge (Bragança)

Os predadores da processionária do pinheiro (Thaumetopoea pityocampa Schiff.) contribuem para a regulação das suas populações em todas as fases do seu desenvolvimento. Algumas espécies da família Tettigonidae são, segundo a bibliografia, os principais responsáveis pela predação de ovos desta praga desfolhadora

DC-DC power converter for high power solar photovoltaic system

Worldwide there is an enormous dependence on fossil fuels to produce electricity. Burning fossil fuels results in CO2 emission into the atmosphere, causing a negative environmental impact. In order to mitigate these problems, there is a need to integrate renewable energy sources into the power grid, namely solar photovoltaic (PV) energy. Power electronics converter solutions for solar PV module interface are vast and have advantages and disadvantages depending on the purpose. In addition, when the purpose is efficiency, it is important to consider the choice of the most appropriate power semiconductors. This paper presents a study, sizing, and development of a DC-DC power converter for high-power solar PV applications. In this study, a DC-DC boost interleaved power converter with two arms controlled by an incremental conductance Maximum Power Point Tracking (MPPT) control algorithm is proposed. The MPPT is combined with a Proportional-Integral (PI) controller for individual control of the current on each arm and was applied to extract the maximum power available at the solar PV module for different solar radiation and temperature conditions. The digital control system was implemented in a TMS320F28335 microcontroller from Texas Instruments.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the MEGASOLAR Project POCI-01-0247-FEDER-047220. Mr. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018 granted by the Portuguese FCT foundation