1,737 research outputs found

    Novel optical PVC probes for on-site detection/determination of fluoroquinolones in a solid/liquid interface: Application to the determination of Norfloxacin in aquaculture water

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    A novel optical disposable probe for screening fluoroquinolones in fish farming waters is presented, having Norfloxacin (NFX) as target compound. The colorimetric reaction takes place in the solid/liquid interface consisting of a plasticized PVC layer carrying the colorimetric reagent and the sample solution. NFX solutions dropped on top of this solid-sensory surface provided a colour change from light yellow to dark orange. Several metals were tested as colorimetric reagents and Fe(III) was selected. The main parameters affecting the obtained colour were assessed and optimised in both liquid and solid phases. The corresponding studies were conducted by visible spectrophotometry and digital image acquisition. The three coordinates of the HSL model system of the collected image (Hue, Saturation and Lightness) were obtained by simple image management (enabled in any computer). The analytical response of the optimised solid-state optical probe against concentration was tested for several mathematical transformations of the colour coordinates. Linear behaviour was observed for logarithm NFX concentration against Hue+Lightness. Under this condition, the sensor exhibited a limit of detection below 50 μM (corresponding to about 16 mg/mL). Visual inspection also enabled semi-quantitative information. The selectivity was ensured against drugs from other chemical groups than fluoroquinolones. Finally, similar procedure was used to prepare an array of sensors for NFX, consisting on different metal species. Cu(II), Mn(II) and aluminon were selected for this purpose. The sensor array was used to detect NFX in aquaculture water, without any prior sample manipulation

    Can oil, plastic and RAP wastes have a new life in novel asphalt mixtures?

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    The pavement recycling allows to reuse reclaimed asphalt pavement (RAP) or other waste materials in new asphalt mixtures for road construction or rehabilitation, thus re-ducing the use of virgin materials (aggregates and bitumen). Thus, the main aim of this study is to minimize the use of natural resources through the reuse of three waste materials: HDPE, mo-tor oil and RAP. Different amounts of waste motor oil and HDPE were added to an asphalt binder with 50% aged bitumen. The best solutions to produce the modified binders (4.5 to 5.0% HDPE and 10 % waste motor oil) performed as well as a conventional bitumen although they only used 35 % of virgin bitumen. Asphalt mixtures with 50 % RAP were produced with the selected modified binders, improving some characteristics in comparison with conventional asphalt mixtures. In conclusion, these wastes can revive in new asphalt mixtures.RDF funds through the Operational Compe titiveness Program – COMPETE and the National funds by FCT – Portuguese Foundation for Science and Technology in the scope of PLASTIROADS Project FCOMP - 01 - 0124 - FEDER - 020335 (PTDC/ECM/119179/20

    Antimicrobial performance of lignin embedded in bacterial nanocellulose membranes

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    The development of bio-based antimicrobial polymeric composites has never been so urgent. Novel antimi- crobial fibrous-based biocomposites will certainly allow the development of important solutions to fight the present and future Pandemics, while reducing the dependence of petrochemical based polymers and fibers. Lignin has a pivotal function in preventing the invasion of phytopathogens, thus, this work explores the anti- microbial potential of lignin when embedded in a biosynthesized fibrous nanomatrix with superior mechanical properties: bacterial nanocellulose (BNC). Lignin was subjected to alkali treatment to promote the inclusion of lignin within BNC which comprises pores ranging from 20 to 300 nm. Both alkali treatment efficiency, bac- tericidal and antiviral activities were investigatedThe authors would like to acknowledge the project PLASMAMED - PTDC/CTM-TEX/28295/2017 fnanced by FCT, FEDER and POCI in the frame of the Portugal 2020 program, the project UID/CTM/00264/2019 of 2C2T under the COMPETE and FCT/MCTES (PIDDAC) co-fnanced by FEDER through the PT2020 program. Liliana Melro acknowledges her Doctoral grant awarded by FCT (2020.04919.BD)

    A critical review on the numerical simulation related to Physical Vapour Deposition

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    Physical Vapour Deposition (PVD) is a process usually used for the production of advanced coatings regarding its application in several industrial and current products, such as optical lens, moulds and dies, decorative parts or tools. This process has several variants due to its strong evolution along the last decades. The process is commonly assisted by plasma, creating a particular low pressure and medium temperature atmosphere, which is responsible for the transition of atomic particles between the target and the parts to be coated into a vacuum reactor. Several parameters are directly affecting the deposition, namely the substrate temperature, pressure inside the reactor, assisting gases used, type of current, power supply, bias, substrate and target materials, samples holder and corresponding rotation, deposition time, among others. Many mathematical models have been developed in order to allow the generation of numerical simulation applications, trying to combine parameters and expect the corresponding results. Numerical simulation applications were created around the mathematical models previously developed, which can play an important role in the prediction of the coating properties and structure. This paper intends to describe the numerical simulation evolution in the last years, namely the use of Finite Elements Method (FEM) and Computational Fluid Dynamics (CFD).LAETA/CETRIB/INEGI Research Center- FLAD – Fundação Luso-Americana para o Desenvolvimento | Ref. 116/2018Fundação para a Ciência e a Tecnologia | Ref. UID/EMS/0615/201

    Plastic waste use as aggregate and binder modifier in open-graded asphalts

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    Road pavements are very important infrastructures for the Society, but they can cause serious environmental impacts during construction, operation and rehabilitation phases. Thus, it is essential to develop surface paving solutions that promote not only the durability but also a comfortable and safe use. In fact, this work aims to study the properties of new opengraded mixtures for surface layers produced with plastic wastes. First, HDPE and EVA wastes were used as bitumen modifiers, and then another plastic waste (PEX) replaced part of the aggregates. After studying the modified binders, the open-graded mixtures were designed, and then they were tested concerning their particle loss, rutting resistance, surface texture and damping effect. It was concluded that both ways of using the plastic wastes can improve the mechanical and functional properties of the open-graded mixtures related to the pavement performance.ERDF funds through the Operational Competitiveness Program – COMPETE and the National funds by FCT – Portuguese Foundation for Science and Technology in the scope of PLASTIROADS Project FCOMP-01-0124-FEDER-020335 (PTDC/ECM/119179/2010)

    Using COSMO-RS to design choline chloride pharmaceutical eutectic solvents

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    Deep eutectic solvents (DES) present interesting properties, mostly connected to their solvation ability, and have been subject to much research in the recent past. Currently, the discovery of new eutectic solvents is accomplished by experimentally measuring the eutectic point of random systems, often using choline chloride as a hydrogen bond acceptor. In this work, the eutectic temperatures of new choline chloride-based eutectic systems were experimentally assessed. These data, along with other previously reported in the literature, were used to evaluate a method based on COSMO-RS to predict the eutectic temperature of choline-chloride based mixtures. The predictive methodology herein developed allows for the quick scanning of a large matrix of systems in order to identify those more promising to be in the liquid state at a given temperature. To validate this method, the eutectic temperature of pharmaceutical drug mixtures was predicted and, then, assessed experimentally, showing that COSMO-RS is useful in the design of liquid drug-based formulations.This work was developed in the scope of the project CICECO e Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013) and Associate Laboratory LSRE-LCM, POCI- 01-0145-FEDER-006984 (Ref. FCT UID/EQU/50020/2013), and project MultiBiorefinery (POCI-01-0145-FEDER-016403), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDDER under the PT2020 Partnership Agreement. FCT is also acknowledged for funding the project DeepBiorefinery (PTDC/AGRTEC/1191/2014). Marcos Larriba also thanks Ministerio de Eduación, Cultura y Deporte of Spain for awarding him a José Castillejo postdoctoral mobility grant (CAS17/00018).info:eu-repo/semantics/publishedVersio

    Antibacterial properties of bacterial nanocellulose functionalized with metal nanoparticles via in situ synthesis

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    [Excerpt] Wound infections are generally caused by pathogens and multidrug-resistant (MDR) strains that render the administration of antibiotics ineffective. An alternative is to treat infected wounds at the initial stage using a fibrous bionanopolymer, bacterial nanocellulose (BNC), functionalized with antimicrobial metal nanoparticles (MNPs). BNC is a highly promising wound dressing due to its very high-water retention capacity (> 99 %) and high porosity. Such properties enable the absorbance of exudates, whilst maintaining the environment moist allowing the exchange of air. However, BNC is absent of antibacterial properties, thus gold (Au), copper (Cu), and copper oxide (Cu2O) NPs were incorporated within the nanofibrous structure of the biopolymer via in situ synthesis

    Empatía por defecto: correlatos en el cerebro en reposo

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    Background: Empathy, defined as the ability to access and respond to the inner world of another person, is a multidimensional construct involving cognitive, emotional and self-regulatory mechanisms. Neuroimaging studies report that empathy recruits brain regions which are part of the social cognition network. Among the different resting state networks, the Default Mode Network (DMN) may be of particular interest for the study of empathy since it has been implicated in social cognition tasks. Method: The current study compared the cognitive and emotional empathy scores, as measured by the Interpersonal Reactivity Index, with the patterns of activation within the DMN, through the neuroimaging methodology of resting-state functional magnetic resonance. Results: Results suggest a significant positive correlation between cognitive empathy and activation of the bilateral superior medial frontal cortex nodes of the DMN. Contrastingly, a negative correlation was found between emotional empathy and the same brain region. Conclusions: Overall, this data highlights a critical role of the medial cortical regions of the DMN, specifically its anterior node, for both cognitive and emotional domains of the empathic process.Antecedentes: la empatía, defi nida como la capacidad de acceder y responder al mundo interior de otra persona, es un constructo multidimensional que implica mecanismos cognitivos, emocionales y autorreguladores. Los estudios de neuroimagen informan que la empatía recluta regiones cerebrales que forman parte de la red de cognición social. Entre las diferentes redes de estado de reposo, la Red Neuronal por Defecto (Default Mode Network; DMN) puede ser de particular interés para el estudio de la empatía, ya que ha sido implicada en tareas de cognición social. Método: el presente estudio comparó los valores de empatía cognitiva y emocional, medidos por medio del Índice de Reactividad Interpersonal, con los patrones de activación dentro de la DMN, a través de la metodología de neuroimagen por resonancia magnética funcional en estado de reposo. Resultados: los resultados sugieren una correlación positiva signifi cativa entre la empatía cognitiva y la activación bilateral de los nodos de la región frontomedial superior de la DMN. En contraste, se encontró una correlación negativa entre la empatía emocional y la misma región del cerebro. Conclusiones: en general, estos datos destacan un papel crítico de las regiones corticales mediales de la DMN, específi camente su nodo anterior, para los dominios cognitivo y emocional del proceso empático.This study was supported by the Bial Foundation, under the fellowship numbers 89/08 and 87/12 and by the PFST Ref. UID/CED/04872/2016, Ref. SFRH/BD/65892/2009, Ref. PTDC/PSIPCL/115316/2009, and FEDER funds. Ref. POCI-01-0145-FEDER-007653.info:eu-repo/semantics/publishedVersio

    Bio-synthesised fibrous-based meshes for abdominal hernia with enhanced mechanical and antimicrobial properties

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    Abdominal hernia (AH) encompasses the most prevalent types of hernia: inguinal, umbilical and incisional. Notwithstanding current hernia complications represent a low death toll (nearly 0.001 % in developed countries), non-reducible hernias are the most severe cases, which require urgent surgical intervention due to their life-threatening nature. In a single year, at the United States of America, more than 800 thousand surgeries are performed to repair inguinal hernias. Abdominal hernia ubiquitous symptoms include pain, which may represent a mild discomfort or even an impairing morbidity. Nevertheless, some patients suffer from morbidity in the post-operative period. Recurrence was reduced when the application of a propylene mesh replaced primary suture repair more than 60 years ago. Surprisingly, currently the most prevalent hernia mesh materials are based on petrochemical plastics such as polypropylene, polyester, polystyrene and expanded polytetrafluoroethylene. Unfortunately, despite the plethora of commercial hernia meshes, an improvement of the hernia meshes is still warranted, since petrochemical materials exhibit a deterioration over time which generate complications and recurrence. This project envisages the complete replacement of the conventional plastic-based material of hernia meshes by a fully bio- based material with superior mechanical properties: bacterial nanocellulose (BNC). BNC is synthesized by bacteria and is composed of a 3D matrix of 100 % nanofibrils of cellulose, each with a diameter ranging between 20 to 100 nm. When BNC producing bacterium are cultured in static culture, the BNC is formed as membrane (nanoporous mesh comprising pores of 100 to 300 nm in diameter) at the surface of the culture medium and adopts the shape of the available surface. Therefore, it is easy to control the membrane surface shape, as well as its thickness, which can be controlled by the incubation time (longer incubation time will result in a larger thickness). The selection of the most adequate bacterium for the production of the hernia mesh will be performed Nevertheless, for a hernia mesh to be viable it requires pores with a specific diameter to allow the permeability of leukocytes, fibroblasts, and permit the arrangement of collagen and blood vessels. Per se, the BNC mesh does not possess such large specific pores with the required diameter (> 75 μm), thus it is proposed the design and development of a template to achieve a AH mesh that meets the necessary requirements. Furthermore, due to the high complexity of hernia mesh infection, which is extremely difficult to adequately treat without removing the mesh, this project envisages the functionalization of BNC AH mesh with antimicrobial properties. Two approaches will be considered for the BNC AH mesh functionalization, namely: in situ synthesis and adsorption through filtration. NPs optimal concentration and functionalization process will be examined and tailored to obtain a BNC AH mesh with effective antimicrobial activity and negligible cytotoxicity. According the AH implantation site, three different hernia meshes classes are usually applied: low, medium and high weight, thus the optimal antimicrobial BNC meshes of each class will be patented to represent a viable commercial alternative, by displaying superior mechanical properties, biocompatibility and low infection propensity, to considerably improve AH patience overall wellbeing.FEDER funds under the COMPETE program and by National Funds through Fundação para a Ciência e Tecnologia (FCT) under the project POCI-01- 0145-FEDER-007136 and UID/CTM/00264/2013. PLASMAMED project PTDC/CTMTEX/28295/2017 funded by FCT, FEDER e POCI through the program Portugal 202

    Bacterial nanocellulose films loaded with nisin Z -antibacterial efficacy against Staphylococcus aureus strains

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    Burn wounds can lead to numerous severe complications including bacterial infections causing patient morbidity and mortality, mostly in low- and middle-income countries. The Grampositive bacteria Staphylococcus aureus is one of the major causes of nosocomial infections in burn patients. Furthermore, the considerable increase of the microbial resistance against traditional antibiotics is leading towards alternative strategies to treat bacterial infections. Nisin Z is an antimicrobial peptide which exhibits a significant antibacterial activity against Gram-positive bacteria. The incorporation of peptide and other biomolecules within a biopolymer matrix provides protection maintaining their antimicrobial potential. Bacterial nanocellulose (BNC) has been widely used as wound dressings. Its impressive water retention capacity (>99%) and porosity are beneficial to manage wounds due to its potential to absorb exudates, providing a breathable and humid environment. In this work, the functionalization of BNC with nisin Z (BNC-NZ) via vacuum filtration is reported. The entrapment of the peptide inside the BNC films was confirmed through morphological characterization using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectrometry. Typical absorbance peaks of nisin Z are easily identifiable at 1647 cm−1 (amide group) and 1520 cm-1 (bending of primary amines). Thermal Gravimetric Analysis (TGA) suggested that nisin Z did not interfere with the BNC matrix. The antimicrobial activity of nisin Z against S. aureus strains including a multiple drug-resistant, was verified by Minimum Bactericidal Concentration (MBC). Agar Diffusion and Shake Flask methods revealed the potential of BNC-NZ for prospective applications in burn wound dressings
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