Extractability and mobility of mercury from agricultural soils surrounding industrial and mining contaminated areas

This study focussed on a comparison of the extractability of mercury in soils with two different contamination sources (a chlor-alkali plant and mining activities) and on the evaluation of the influence of specific soil properties on the behaviour of the contaminant. The method applied here did not target the identification of individual species, but instead provided information concerning the mobility of mercury species in soil. Mercury fractions were classified as mobile, semi-mobile and non-mobile. The fractionation study revealed that in all samples mercury was mainly present in the semi-mobile phase (between 63 and 97%). The highest mercury mobility (2.7 mg kg-1) was found in soils from the industrial area. Mining soils exhibited higher percentage of non-mobile mercury, up to 35%, due to their elevated sulfur content. Results of factor analysis indicate that the presence of mercury in the mobile phase could be related to manganese and aluminum soil contents. A positive relation between mercury in the semi-mobile fraction and the aluminium content was also observed. By contrary, organic matter and sulfur contents contributed to mercury retention in the soil matrix reducing the mobility of the metal. Despite known limitations of sequential extraction procedures, the methodology applied in this study for the fractionation of mercury in contaminated soil samples provided relevant information on mercury's relative mobility

Supercritical antisolvent precipitation of PHBV microparticles

The micronization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from organic solutions using supercritical antisolvent (SAS) technique has been successfully achieved. SASexperiments were carried out at different operational conditions and microspheres with mean diameters ranging from 3 to 9 mwere obtained. The effect of CO2 and liquid flow, temperature and pressure on particle size and particle size distribution was evaluated. The microspheres were precipitated from a dichloromethane (DCM) solution. The best process conditions for this mixture were, according to our study, 40 ◦C, 100 bar, 1mLmin−1 liquid flow and 10 L min−1 carbon dioxide flow. Experiments with polymers containing different HV percentages were carried out. The powders obtained became more spherical as the HV content decreased

Conceptions of learning among Portuguese students of Elementary Education

Pretendeu-se conhecer as concepções de aprendizagem de estudantes portugueses do 1º ciclo do Ensino Básico, verificando a possível replicação e inovação em relação às concepções identificadas pela perspectiva fenomenográfica. Realizaram-se entrevistas semiestruturadas centradas em três dimensões da concepção de aprendizagem: referencial (o que é a aprendizagem), processual (como se aprende) e contextual (onde se aprende). Uma análise de conteúdo de tipo intermédio das respostas demonstrou uma correspondência entre as concepções encontradas e as concepções básicas reveladas pela fenomenografia (por exemplo, aprendizagem como acumulação de informação, como compreensão ou como obtenção de classificações) e também permitiu desvendar novas concepções de aprendizagem, representando-a como realização de atividades específicas, devolução da informação por explicação, ou realizável através do esforço pessoal e autônomo.Cette étude vise à comprendre les concepts d’apprentissage des étudiants portugais du primaire, en vérifiant la réplication et l’innovation possibles par rapport aux conceptions identifiées par la perspective phénoménographique. Des entretiens semi-structurés ont été conduits, centrés sur trois dimensions de la conception de l’apprentissage: référentiel (ce qu’est l’apprentissage), procédural (comment on l’a appris), contextuel (où l’on apprend). Une analyse de contenu de type intermédiaire des réponses a démontré une correspondance entre les concepts trouvés et les concepts de base révélés par la Phénoménographie (par exemple, l’apprentissage comme accumulation d’informations, comme compréhension ou comme obtention des classifications) et a également permis de dévoiler de nouvelles conceptions d’apprentissage, en les représentant comme la réalisation d’activités spécifiques, le retour de l’information par explication, ou réalisables grâce à des efforts personnels et autonomes.Se pretendió conocer las concepciones de aprendizaje de estudiantes portugueses del 1.º ciclo de la enseñanza básica y verificar la posible replicación e innovación sobre las concepciones identificadas por la perspectiva fenomenográfica. Se realizaron entrevistas semiestructuradas, centradas en tres dimensiones de la concepción del aprendizaje: referencial (qué es el aprendizaje); procesual (cómo se aprende); y contextual (dónde se aprende). Un análisis de contenido de tipo intermedio de las respuestas demostró una correspondencia entre las concepciones encontradas y las concepciones básicas reveladas por la fenomenografía (por ejemplo, aprendizaje como acumulación de información, como comprensión o como obtención de clasificaciones) y también permitió desvelar nuevas concepciones de aprendizaje, que la representan como una realización de actividades específicas, como la devolución de la información por explicación, o realizable por medio del esfuerzo personal y autónomo.The aim of this study is to understand the conceptions of learning of elementary Portuguese students, by investigating possible replications and innovations in relation to the conceptions identified by phenomenographic research. Semi-structured interviews were conducted, centered on three dimensions of conceptions of learning: referential (what is learning), procedural (how to learn), contextual (where one learns). Intermediate thematic analysis of the answers to the interviews showed a correspondence between observed learning conceptions and the basic conceptions revealed by Phenomenography (e.g., learning as accumulation of information, as comprehension or as a way to obtain school grades) and also allowed to unveil the existence of new conceptions of learning, which represent learning as the performance of specific activities, a return of information by explanation, or as an outcome achievable through personal and autonomous effort

A comparison between gravimetric and in-situ spectroscopic methods to measure the sorption of CO₂in a biocompatible polymer

In situ ATR-IR spectroscopy was used to simultaneously measure the sorption and swelling of carbon dioxide at high pressures in a biocompatible acrylate copolymer poly(methylmethacrylate-co-ethylhexylacrylate-co-ethyleneglycoldimethacrylate), P(MMA–EHA–EGDMA). The ν3 band of CO2 dissolved in the polymer (at 2335 cm−1) was used to calculate the sorption data and the polymer swelling was determined by analyzing the changes in the absorbance of the ν(C O) band (at 1730 cm−1) of the polymer. Transmission spectroscopy in the near-IR region was also used to study the sorption of CO2 in the polymer using combinational and overtone bands. The experiments were carried out in a pressure range of 2.0–12.0MPa and in a temperature range of 27–40 ◦C. The data for CO2 sorption in this polymer obtained by in situ spectroscopic methods have been compared to the data obtained by the gravimetric technique

Preparation of controlled release microspheres using supercritical fluid technology for delivery of anti-inflammatory drugs

Ethylcellulose/methylcellulose blends were produced using different precipitation techniques and impregnated with naproxen, a non-steroidal anti-inflammatory drug (NSAID). Solvent-evaporation technique was used not only for the preparation of ethylcellulose/methylcellulose microspheres but also to encapsulate naproxen. Supercritical fluid (SCF) impregnation was also performed to prepare naproxen loaded microspheres. The microspheres, impregnated by the SCF technique, were prepared both by solvent-evaporation and by a supercritical antisolvent (SAS) process. In vitro release profiles at pH 7.4 and 1.2, of naproxen-loaded microspheres were evaluated and the results were modelled Fick’s law of diffusion and Power law. Miscrospheres prepared by supercritical antisolvent have a higher loading capacity and present a slower release profile. The systems studied present a release mechanism controlled by drug diffusion which complies Fick’s law of diffusion

Preparation of ethylcellulose/methylcellulose blends by supercritical antisolvent precipitation

The supercritical antisolvent (SAS) techniquewas used to prepare ethyl cellulose/methyl cellulose blends, two biocompatible polymers commonly used as drug carriers in controlled delivery systems. Ethyl cellulose is widely used as a drug carrier. The drug release of the delivery devices can be controlled to some extent by addition of a water-soluble or water swellable polymer, such as methyl cellulose. This leads to the solubility enhancement of poorly water-soluble molecules. SAS experiments were carried out at different operational conditions and microspheres with mean diameters ranging from 5 to 30 m were obtained. The effect of CO2 and liquid flow, temperature and pressure on particle size and particle size distribution was evaluated. The microspheres were precipitated from a mixture of dichloromethane (DCM) and dimethylsulfoxide (DMSO) (4:1 ratio). The best process conditions for this mixture were according to our study 40 ◦C and 80 bar

Preparation of acetazolamide composite microparticles by supercritical antisolvent techniques

The possibility of preparation of ophthalmic drug delivery systems using compressed anti-solvent technology was evaluated. and RL 100 were used as drug carriers, acetazolamide was the model drug processed. Compressed anti-solvent experiments were carried out as a semi-continuous or a batch operation from a liquid solution of polymer(s) + solute dissolved in acetone. Both techniques allowed the recovery of composite particles, but the semi-continuous operation yielded smaller and less aggregated populations than the batch operation. The release behaviour of acetazolamide from the prepared microparticles was studied and most products exhibited a slower release than the single drug. Moreover, the release could be controlled to some extent by varying the ratio of the two Eudragit used in the formulation and by selecting one or the other anti-solvent technique. Simple diffusion models satisfactorily described the release profiles. Composites specifically produced by semi-continuous technique have a drug release rate controlled by a diffusion mechanism, whereas for composites produced by the batch operation, the polymer swelling also contributes to the overall transport mechanism

Subcritical carbon dioxide foaming of polycaprolactone for bone tissue regeneration

Accepted manuscriptThe preparation of three-dimensional polycaprolactone scaffolds using dense CO2 as foaming agent, without supercritical conditions, was evaluated in this study towards future applications in bone repair. Herein, 3D foams were obtained at 5.0 MPa and 45 °C. To induce bioactivity, β-tricalcium phosphate (β-TCP, 10 wt%) and dexamethasone (5 and 10 wt%) were dispersed in the scaffolds. Foams revealed a pore size range of 164–882 μm, 73–99% porosity and 79–99% interconnectivity, assessed by micro-computed tomography, and a Young modulus of 1.76–2.92 MPa. Dexamethasone did not impair morphology of the matrices in comparison with PCL+β-TCP, which presented a water uptake of nearly 100% after 14 days. A sustained release of dexamethasone was achieved over 35 days in physiologic solution. This study reports the feasibility of using dense CO2 to produce in one-step a porous matrix loaded with active agents opening new possibilities towards injectable systems for in situ foamingEuropean Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number REGPOT-CT2012-316331-POLARIS. It was also funded by the project “Novel smart and biomimetic materials for innovative regenerative medicine approaches” (RL1-ABMR-NORTE-01-0124-FEDER-000016) co-financed by North Portugal Regional Operational Programme (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) and the project NORTE‐01‐0145‐FEDER‐000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement. The authors would like to acknowledge the funding of the project Associate Laboratory ICVS/3B’s, under grant agreement number POCI-01-0145-FEDER-007038 supported by FEDER, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT)info:eu-repo/semantics/publishedVersio

Evaluating weaknesses of "perceptual-cognitive training" and "brain training" methods in sport: An ecological dynamics critique

The recent upsurge in "brain training and perceptual-cognitive training," proposing to improve isolated processes, such as brain function, visual perception, and decision-making, has created significant interest in elite sports practitioners, seeking to create an "edge" for athletes. The claims of these related "performance-enhancing industries" can be considered together as part of a process training approach proposing enhanced cognitive and perceptual skills and brain capacity to support performance in everyday life activities, including sport. For example, the "process training industry" promotes the idea that playing games not only makes you a better player but also makes you smarter, more alert, and a faster learner. In this position paper, we critically evaluate the effectiveness of both types of process training programmes in generalizing transfer to sport performance. These issues are addressed in three stages. First, we evaluate empirical evidence in support of perceptual-cognitive process training and its application to enhancing sport performance. Second, we critically review putative modularized mechanisms underpinning this kind of training, addressing limitations and subsequent problems. Specifically, we consider merits of this highly specific form of training, which focuses on training of isolated processes such as cognitive processes (attention, memory, thinking) and visual perception processes, separately from performance behaviors and actions. We conclude that these approaches may, at best, provide some "general transfer" of underlying processes to specific sport environments, but lack "specificity of transfer" to contextualize actual performance behaviors. A major weakness of process training methods is their focus on enhancing the performance in body "modules" (e.g., eye, brain, memory, anticipatory sub-systems). What is lacking is evidence on how these isolated components are modified and subsequently interact with other process "modules," which are considered to underlie sport performance. Finally, we propose how an ecological dynamics approach, aligned with an embodied framework of cognition undermines the rationale that modularized processes can enhance performance in competitive sport. An ecological dynamics perspective proposes that the body is a complex adaptive system, interacting with performance environments in a functionally integrated manner, emphasizing that the inter-relation between motor processes, cognitive and perceptual functions, and the constraints of a sport task is best understood at the performer-environment scale of analysis

Chitosan and polyethylene glycol based membranes with antibacterial properties for tissue regeneration

The prevention of microbial infections associated with implantable medical devices and superficial wounds represents one of the main research strategies in the field of biomaterials. The present study reports on the development of composite membranes of Chitosan (CS)-Polyethylene glycol (PEG) matrix, incorporating particles of biphasic calcium phosphate (BCP), zinc oxide (ZnO) and copper oxide (CuO). The properties that are relevant for intended applications in tissue regeneration and antibacterial coatings of implants were assessed. It was found that the addition of 1% (w/w - relative to the mass of CS) of each metal oxide promoted satisfactory bacteriostatic activity and exhibited no cytotoxic effects towards the Vero cell line. The formation of bonds between the CS/PEG matrix and ionic species from the powders enhanced the cross-linking degree and mechanical properties of composite membranes in comparison to the non-doped membrane with the same polymer matrix (CS/PEG = 70/30%). A gradual degradation of the composite membranes over the immersion time in simulated body fluid (SBF) was accompanied by a continuous surface deposition of uniform apatite layer.publishe