Adsorption of carbon dioxide, methane, and nitrogen on zn(Dcpa) metal-organic framework

Norma Transitória DL 57/2016 ELAC2014/BEE0367Adsorption-based processes using metal-organic frameworks (MOFs) are a promising option for carbon dioxide (CO2 ) capture from flue gases and biogas upgrading to biomethane. Here, the adsorption of CO2, methane (CH4 ), and nitrogen (N2 ) on Zn(dcpa) MOF (dcpa (2,6-dichloro-phenylacetate)) is reported. The characterization of the MOF by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and N2 physisorption at 77 K shows that it is stable up to 650 K, and confirms previous observations suggesting framework flexibility upon exposure to guest molecules. The adsorption equilibrium isotherms of the pure components (CO2, CH4, and N2 ), measured at 273–323 K, and up to 35 bar, are Langmuirian, except for that of CO2 at 273 K, which exhibits a stepwise shape with hysteresis. The latter is accurately interpreted in terms of the osmotic thermodynamic theory, with further refinement by assuming that the free energy difference between the two metastable structures of Zn(dcpa) is a normally distributed variable due to the existence of different crystal sizes and defects in a real sample. The ideal selectivities of the equimolar mixtures of CO2 /N2 and CO2 /CH4 at 1 bar and 303 K are 12.8 and 2.9, respectively, which are large enough for Zn(dcpa) to be usable in pressure swing adsorption.publishersversionpublishe

Two-column relay simulated moving-bed for gas-phase separations

A new two-column, relay, simulated moving bed process (2-column R-SMB) for gas-phase separations has been designed and implemented experimentally in this work. R-SMB differs from classical SMB processes by avoiding the partial withdrawal of products, since the outlet streams are handled in a relay mode. The outlet streams are either fully collected as product/waste or completely recycled to another column. In this work, the relay concept is applied for the first time in 2-column SMB processes and gas-phase separations. The process is designed and optimized through model-based computational simulation and the results obtained are validated experimentally. For the purpose, a new experimental lab-scale unit was designed and assembled. Please click Additional Files below to see the full abstract

An MCDM approach to the selection of novel technologies for innovative in-vehicle information systems

Driving a car is a complex skill that includes interacting with multiple systems inside the vehicle. Today’s challenge in the automotive industry is to produce innovative In-Vehicle Information Systems (IVIS) that are pleasant to use and satisfy the costumers’ needs while, simultaneously, maintaining the delicate balance of primary task vs. secondary tasks while driving. The authors report a MCDM approach for rank ordering a large heterogeneous set of human-machine interaction technologies; the final set consisted of hundred and one candidates. They measured candidate technologies on eight qualitative criteria that were defined by domain experts, using a group decision-making approach. The main objective was ordering alternatives by their decision score, not the selection of one or a small set of them. The authors’ approach assisted decision makers in exploring the characteristics of the most promising technologies and they focused on analyzing the technologies in the top quartile, as measured by their MCDM model. Further, a clustering analysis of the top quartile revealed the presence of important criteria trade-offs.Operational Competitiveness Program – COMPETE, QREN (Quadro de Referência Estratégico Nacional), European Regional Development Funds (European Union), R&D project in joint-promotion (HMIEXCEL-2013-2015 36265/2013) HMIEXCEL - I&D crítica em torno do ciclo de desenvolvimento e produção de soluções multimédia avançadas para automóvelStrategic program FCT-UID/EEA/00066/2013Fundação para a Ciência e a Tecnologia (IF/00217/2013)Fundação para a Ciência e a Tecnologia (PD/BD/105966/2014

In vitro digestion of protein-based nanohydrogels incorporating curcumin as a lipophilic model compound: effect of a chitosan coating

[Excerpt] Introduction: One of the challenges of food enrichment with lipophilic bioactive compounds is related with their poor solubility in food matrices and their instability during digestion, leading to a poor bioavailability. These challenges are promoting research efforts to find more effective delivery systems based on natural biopolymers. Protein nanohydrogels can be used as carriers of bioactive compounds in food products, however, during gastric digestion, proteins are denatured by environmental conditions and hydrolyzed by enzymes. One of the strategies to improve protein nanohydrogels’ stability and the controlled release of active ingredients during gastrointestinal (GI) digestion is the addition of a coating (polysaccharide layer). The behavior of lactoferrin (Lf)–glycomacropeptide (GMP) nanohydrogels with and without a chitosan coating was evaluated during GI digestion. [...]info:eu-repo/semantics/publishedVersio

Reactive PLIF method for characterisation of micromixing in continuous high-throughput chemical reactors

This work aimed to test and optimise reactive Planar Laser-Induced Fluorescence (PLIF) methods for the visualisation of the micromixing regions in chemical reactors using standard PLIF and Particle Image Velocimetry (PIV) equipment with the laser source 512 nm. Two methods were tested: (i) an acid–base reaction with fluorescein as the reaction-sensitive tracer and (ii) Fenton’s reaction, with Rhodamine B as the reaction tracer. Both test-reactions were studied in stopped-flow equipment to define suitable operational conditions, namely the chemical composition of the inflow streams, the concentration of reagents and fluorophore, and suitable excitation light wavelength. The visualisation of the micromixing regions was tested in a continuous flow reactor with a T-jet geometry. A laser light sheet emitted from an Nd:YAG laser illuminated the axial section of the demonstration reactor. The mixing dynamics and the reaction course were visualised with the acid–base reactive PLIF images. Fenton’s reactive PLIF method showed the overall distribution of mixing and reaction regions. The main contribution of this work is benchmarking two methods with costs that enable the visualisation of micromixing regions in continuous high-throughput reactors.publishe

Multi-scale modeling of hydraulic fracturing operations

Apresentação efetuada no 17th International Conference of Computational Methods in Sciences and Engineering (ICCMSE 2021), em Crete, Greece, 202

Sensitive areas under radium/uranium mine drainage - the Picoto mine case study, central Portugal

A zona mineira de Picoto está localizada próximo de Vilar Seco (Viseu, Centro de Portugal). Ocorre numa área de declive suave, altitude variando entre 360-380 m, incluída na bacia do rio Cagavaio, com drenagem dominante NE-SW. A mineralização ocorre em veios de quartzo, que intersectam o granito Varisco, porfiróide de duas micas. Os filões de quartzo preenchem falhas N37°-45°E e N50°-70°E, localmente brechificadas. Estes filões contêm meta-torbernite e uranófano, e alguns minerais portadores de U, como clorite e hidróxidos de Fe e Mn. A exploração ocorreu em duas fases, entre 1917 e 1953. Após cessada a exploração, permaneceram as escombreiras resultantes da exploração e a área nunca foi reabilitada. Neste momento, está ocupada por culturas locais, principalmente vinhas e produtos agrícolas. Vinte amostras de águas superficiais e subterrâneas foram colhidas entre 2008 e 2009. Em geral, as águas apresentam valores de pH entre 4.7 a 6.3 e são pouco mineralizadas (CE = 44-190 μS/cm; TDS = 49-137 mg/L). Contudo, algumas águas estão contaminadas em NO2, Fe, Mn, Cu, As e U, e não devem ser utilizadas para consumo humano nem em atividades agrícolas. A contaminação da água está associada principalmente à antiga mina de rádio/urânio e atividades humanas desenvolvidas.The Picoto mine area is located at Vilar Seco village (Viseu, central Portugal), in a soft slope area with altitudes ranging from 360 to 380 m, included in the Cagavaio river catchment, with a dominant NE-SW drainage. The mineralization occurs mainly in quartz veins, which intersect a Variscan porphyritic two-mica granite. The quartz veins fill N37°-45°E and N50°-70°E faults, locally brecciated. The quartz veins contain meta-torbernite and uranophane, and some U-bearing minerals, such as chlorite and Fe- and Mn-hydroxides. The exploitation was carried out in two stages, between 1917 and 1953. Since closure, the area contains mine rejected materials and has never been restored. Therefore, a local cultivated area, mainly for vines and domestic consumption agricultural products, is now deployed. A total of twenty surface and groundwater samples were collected between 2008 and 2009. In general, the waters yield pH values ranging from 4,4 to 6,3 and are poorly mineralized (EC=44-190 µS/cm; TDS= 49-137 mg/L). However, some waters are contaminated with NO₂, Fe, Mn, Cu, As and U and must not be used neither for human consumption nor in agricultural activities. The water contamination is mainly associated with the old radium/uranium mine and subsequent human activities developed in the area.Este trabalho teve suporte financeiro através do ICT e do projeto UID/GEO/04035/2013.info:eu-repo/semantics/publishedVersio

Biodegradable chitosan films with ZnO nanoparticles synthesized using food industry by-products—production and characterization

UIDB/04077/2020 PTDC/BTM‐SAL/29335/2017 UIDB/04138/2020 UIDP/04138/2020 grant (2020.04441.BD) of C.R.This work aimed to produce bionanocomposites of chitosan incorporated with zinc oxide nanoparticles (ZnO NPs) synthesized using food industry by-products and to characterize them. Such nanoparticles are highlighted due to their low cost, antimicrobial activity, accessibility, and sustainability synthesis. Four different levels of ZnO NPs (0, 0.5, 1.0, and 2.0% w/w of chitosan) were tested, and the bionanocomposites were characterized in terms of their hydrophobicity, mechanical, optical, and barrier properties. Overall, the incorporation of ZnO NPs changed the composites from brittle to ductile, with enhanced elongation at break and reduced Young Modulus and tensile strength. Thus, ZnO NPs acted as plasticizer, turning the films more flexible, due to the presence of organic compounds on the NPs. This also favored permeability of oxygen and of water vapor, but the good barrier properties were maintained. Optical properties did not change statistically with the ZnO NPs incorporation. Thus, the characterization presented in this paper may contribute to support a decision on the choice of the material’s final application.publishersversionpublishe

Applications of Essential Oils as Antibacterial Agents in Minimally Processed Fruits and Vegetables - A Review

Microbial foodborne diseases are a major health concern. In this regard, one of the major risk factors is related to consumer preferences for “ready-to-eat” or minimally processed (MP) fruits and vegetables. Essential oil (EO) is a viable alternative used to reduce pathogenic bacteria and increase the shelf-life of MP foods, due to the health risks associated with food chlorine. Indeed, there has been increased interest in using EO in fresh produce. However, more information about EO applications in MP foods is necessary. For instance, although in vitro tests have defined EO as a valuable antimicrobial agent, its practical use in MP foods can be hampered by unrealistic concentrations, as most studies focus on growth reductions instead of bactericidal activity, which, in the case of MP foods, is of utmost importance. The present review focuses on the effects of EO in MP food pathogens, including the more realistic applications. Overall, due to this type of information, EO could be better regarded as an added value to the food industryinfo:eu-repo/semantics/publishedVersio