231 research outputs found

    Effect of Pre-Hydrolysis Reaction Conditions on Xylooligosaccharides Extraction in Eucalyptus Globulus

    Get PDF
    Pre-hydrolysis-kraft of Eucalyptus globulus by autohydrolysis (batch) and with dilute acid hydrolysis (flow-through reactor) were explored in this study, to examine the recovery of xylooligosaccharides (XOs) from the pre-hydrolysis treatment. The results of this work support the potential reuse of the hydrolysate to increase the recovery yield of added value compounds. The pH of the dilute acid hydrolysis was maintained at 3.5 with acetic acid, to mimic the conditions of the batch reactor medium (autohydrolysis). An increase of XOs recovered was evident when the pre-treatment was in the flow-through reactor instead of the batch reactor. In the latter, a high concentration of furfural was recovered, showing the influence of time in XO conversion through hydrolysis. The total yield of pulp was higher in the flow-through reactor (36.4%) in comparison with the batch system (34.5%) after kraft pulping, which was expected, given the increasing time that the hydrolysate was present in the reactor; however, the difference was small and could have been the result of precipitated compounds in the latter, so this needs further analysis. Keywords: cellulose, Eucalyptus globulus, pre-hydrolysis kraft, xylooligosaccharide

    Cursos EFA: alternativas curriculares no distrito de Lisboa: percursos de investigação

    Get PDF
    Colóquio realizado em Cabo Verde, Praia, de 6-7 de julho de 2017A presente investigação tem como objetivos: a) Analisar criticamente o panorama nacional e internacional ao nível das políticas de educação e formação de adultos; b) Caracterizar perspetivas de professores face aos conteúdos dos cursos EFA de nível secundário, e as suas práticas de gestão curricular dos mesmos; c) Descrever o perfil de formação inicial e contínua dos professores dos cursos EFA de nível secundário, bem como as perspetivas desses professores sobre as suas necessidades de formação, e D) Compreender as práticas docentes levadas a cabo pelos professores dos cursos EFA de nível secundário e a sua relação com os resultados dos formandos; contextualizando-se no Distrito de Lisboa. Propomo-nos apresentar o projeto de investigação em curso, com destaque para o design metodológico e o processo e resultado da elaboração e validação de instrumentos de recolha de dados, concretamente, entrevistas semiestruturadas a diversos atores, e inquérito por questionário a professores de cursoThe research we present aims to: a) Analyze critically the national and international panorama in the policies of adult education and training; b) Characterize teachers’ perspectives regarding the contents of secondary level Adult Education and Training (EFA) courses, and their curricular management practices; c) Describe the initial and continuing teacher training profile of the secondary level EFA courses’ teachers, as well as the teachers perspective on their training needs; and d) Understand the teaching practices carried out by the EFA courses teachers and their relation with the results of the trainees; in the context of the District of Lisbon (Portugal). We propose to present the ongoing research project, highlighting the methodological design and the process and result of the elaboration and validation of data collection instruments, namely: semistructured interviews with several actors and questionnaire survey to teachers of secondary level scholar EFA courses.info:eu-repo/semantics/publishedVersio

    Paclitaxel-loaded PLGA nanoparticles: preparation, physicochemical characterization and in vitro anti-tumoral activity

    Get PDF
    The main objective of this study was to develop a polymeric drug delivery system for paclitaxel, intended to be intravenously administered, capable of improving the therapeutic index of the drug and devoid of the adverse effects of Cremophor® EL. To achieve this goal paclitaxel (Ptx)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Ptx-PLGA-Nps) were prepared by the interfacial deposition method. The influence of different experimental parameters on the incorporation efficiency of paclitaxel in the nanoparticles was evaluated. Our results demonstrate that the incorporation efficiency of paclitaxel in nanoparticles was mostly affected by the method of preparation of the organic phase and also by the organic phase/aqueous phase ratio. Our data indicate that the methodology of preparation allowed the formation of spherical nanometric (<200 nm), homogeneous and negatively charged particles which are suitable for intravenous administration. The release behaviour of paclitaxel from the developed Nps exhibited a biphasic pattern characterised by an initial fast release during the first 24 h, followed by a slower and continuous release. The in vitro anti-tumoral activity of Ptx-PLGA-Nps developed in this work was assessed using a human small cell lung cancer cell line (NCI-H69 SCLC) and compared to the in vitro anti-tumoral activity of the commercial formulation Taxol®. The influence of Cremophor® EL on cell viability was also investigated. Exposure of NCI-H69 cells to 25 [mu]g/ml Taxol® resulted in a steep decrease in cell viability. Our results demonstrate that incorporation of Ptx in nanoparticles strongly enhances the cytotoxic effect of the drug as compared to Taxol®, this effect being more relevant for prolonged incubation times.http://www.sciencedirect.com/science/article/B6T3D-46SG28H-4/1/5653b932f0531b537a3a12747fab894

    Refining rheological response of chemical pulp fibre suspensions

    Get PDF
    The purpose of this work was to study the influence of the refining operating variables on the rheological response of chemical pulp fibre suspensions using a Valley beater. Pinus sylvestris, Eucalyptus globulus and Betula verrucosa bleached pulps were used. The normal and tangential average forces exerted on the pulp suspension in the gap clearance were evaluated, the gap between rotor and stator was measured and the apparent viscosity evolution during refining was obtained. The refining essays took place in a laboratory Valley beater, and the studied variables were the load on the roll, the rotor speed of rotation and the specific applied energy. Relationships between apparent viscosity and shear rate were tested for the three species fibre suspensions, which showed shear-thinning behaviour (Fig.1). The results were analysed in terms of fiber and flock properties. The computed crowding factors, Nc, (Kerekes and Schell) decrease from pine to eucalypt to birch. Thus, flock dimensions and resistance are significantly higher for pine. Pine had significantly wider gap, due to its greater and more resistant flocks. This produced smaller shear rate and thus higher apparent viscosity. The smaller and weaker eucalyptus and birch flocks induced smaller gaps, higher shear rates and smaller apparent viscosity. For each pulp suspension, the apparent viscosity diminished with refining time due to increased fibre flexibility and shortening, which promoted smaller flocks and reduced gap clearance (producing higher shear rates). The different rheological behaviors under the same operating conditions for different pulps lead to the inference that from the hydrodynamical point of view one should treat pulps with different morphological characteristics separately, considering the optimization of the energy transfer efficiency in pulp refining.info:eu-repo/semantics/publishedVersio

    Treatment of Industrial Effluents by the Microalgae Selenastrum Sp.

    Get PDF
    High consumption of clean water results in the generation of effluents that need to be treated and then safely discarded. Conventional methods for such treatment often do not offer an economical and sustainable result; therefore, new methods are needed, such as microalgae usage. Microalgae are unicellular beings capable of rapid adaptation, growth, and production of compounds of interest (pharmaceuticals, biofuels and others). This work aimed to study the effectiveness of the microalgae Selenastrum sp. in the treatment of effluents from the textile and pulp &amp; paper industries, as well as the respective effects on its biomass development and accumulation of compounds. Four types of culture were carried out (for each type of effluent, a control, and a control with addition of glucose) lasting eight days, in duplicate, all with the addition of a standard culture medium and controlled abiotic factors. Analyses for compound removal (chemical oxygen demand and colour readings on the 200–800nm range) and biomass development (cell number, its dimensions, and weight) were performed four times during the process. At the end of the experiments, the average removal in effluents for COD and colour were 56.6% and 32.7% respectively, in addition to a biomass accumulation of 0.45 g/L. These results were comparable to those obtained for the control cultivation using glucose as a carbon source (70.0% COD removal and 0.51 g/L biomass accumulation). These results demonstrate the effectiveness of Selenastrum sp. in the treatment of industrial effluents, its resilience in stressful environments and the potential use of its accumulated compounds for biotechnological purposes. Keywords: microalgae, Selenastrum sp., industrial effluent, textile effluent, pulp effluent, effluent treatmen

    Enzymatic hydrolysis of Cytisus striatus: acid sulfite pretreatment optimization

    Get PDF
    Ethanol production from lignocellulosic material includes three major steps: biomass pretreatment, which fragments the lignocellulosic matrix to facilitate the enzymes access to the substrate; hydrolysis, where the polysaccharides are converted into fermentable sugars (e.g. glucose and xylose) [1]; and finally, fermentation that produces ethanol or other biologically based chemicals (e.g. lactic acid, succinic acid) [2]. The aim was to study the effect of pretreatment operative variables, namely sodium bisulfite and sulfuric acid loadings, temperature and time, on released sugars in Cytisus striatus enzymatic hydrolysis with a Novozymes® cocktail. Pre-treatment intends lignin and hemicelluloses removal, reduced cellulose crystallinity and lignocellulosic network porosity increase in order to facilitate enzyme access.info:eu-repo/semantics/publishedVersio

    AVALIAÇÕES CITOLÓGICAS EM OTITES CANINAS POR MALASSEZIA SPP.: ESTUDO RETROSPECTIVO

    Get PDF
    Otitis externa is a condition frequently observed in dogs at the small animal clinics. Malassezia spp. is the most frequently isolated microorganism in the ears of dogs, which is one of the major etiologic agents of ear infections. Identification of this agent may be based on fungal culture or cytology, and the first method is longer and more expensive. The aim of this study was to conduct a retrospective study of the incidence of Malassezia spp. in cases of canine otitis by cytology, in a period of five years. Ear cytology samples from 249 dogs with suspected otitis were evaluated, and were observed positive samples for Malassezia spp. in 44 cases (17.67%), among these 35 dogs (79.5%) with positive cytology in both ears, and 9 dogs (20.5%) were positive for Malassezia in only one ear. In conclusion, dogs with suspected otitis present high incidence of positive Malassezia spp. cytology counts. Cytology revealed to be a useful tool for diagnosis of canine ear infections involving this pathogen, representing diagnostic alternative in cases where the culture is not feasible. However, one must consider that there is no national standard cytological counting yeast cells/field set for cases of canine otitis, which may represent possible misdiagnosis

    Cork Boiling Wastewater Treatment in Pilot Constructed Wetlands

    Get PDF
    most studies published on the topic of cork boiling wastewater (CBW) treatment or valorization used physico-chemical treatment options rather than biological processes. However, the related costs are high and above those of the biological treatment alternative for wastewaters with similar organic loads but from different sources. Thus, con- structed wetland systems (CWs) can be an alternative to conventional biological treatment systems, namely to activated sludge systems, with the prominent virtues of low construction and operation costs. Until today, there is no study or research published for the treatment of CBW using CW systems. Thus, this investigation is a novelty and included the monitoring over a period of four years of the operation of a horizontal subsurface flow constructed wetland (HSF CW) microcosm-scale system planted with common reeds (Phragmites australis) and filled with light expanded clay aggregates (LECA), as support media for the plants and for biofilm development. The contribution of plants to the treatment was assessed by the comparison with an identical wetland unit without plantation (control bed). After this extended period of operation intended to maximize biomass development and acclimatization, which included stepwise increase of the organic load rate (OLR) up to 8.9 g COD/m2/d, the assessment of the treatment capacity of the system was done by doubling the OLR to 16.4 g COD/m2/d during 200 days.info:eu-repo/semantics/publishedVersio

    Higher education methodologies: from urban planning to mathematical issues

    Get PDF
    This article will be focused on higher education learning and teaching methodologies, based on the experience of the Master Degree in Civil Engineering at the University of Beira Interior, in Covilhã (Portugal). It aims to present the results of the practises used by scholar of urban planning and mathematical issues, both regarding the civil engineering research field. Actually, there are some similarities in between the research process features of urban planning domain and mathematics field in order to promote the students’ success. In fact, these both scientific subjects follow analogous tasks in their research processes, not only regarding the same starting point which is the definition of the research problem, but also observing the final phase, which is based on the findings of results, or the proposed solution. It joins scholars from the department of civil engineering and architecture, experts in spatial analysis and scholars from the department of mathematics of the University of Beira Interior (UBI). One case study will be presented as an example and pioneer research of the application of these methodological approaches. It will be focused on the urban planning experiences, associated with postgraduate teachings. It is related to a PhD thesis in Civil Engineering focused on urban planning issues.info:eu-repo/semantics/publishedVersio

    Opportunities for Microalgae-Bacteria Consortium Application to the Treatment of Effluents Generated in Fiber-Waste-Based Recycling Processes

    Get PDF
    Technologies based on microalgae-bacteria seem to be sustainable options for wastewater treatment and reuse, with lower costs than conventional biological treatment technologies. Furthermore, they can generate added-value products produced from algae biomass. Among other advantages, the consortium bacteriaalgae produce photosynthetic oxygen through the microalgae, which can be used by aerobic bacteria for oxidizing organic matter and nitrogen, thus reducing the need for introducing artificial oxygen. In this review paper, the main systems that use microalgaebacteria consortium are discussed. Microalgae-bacteria present advantages in the removal of organics, nitrogen and phosphorus, when compared with conventional biological treatment systems (e.g., activated sludge, percolating filters and ponds), and are able to produce final effluents for reuse (e.g., in agricultural irrigation, industry or aquifer recharge) and excess of microalgae that can be converted to added-value products such as biogas and biofuels. Attention is given to the innovative aspects of applying photobioreators to the treatment and reuse of pulp and paper effluents and fiber-waste-based recycling wastewaters, which seems to open a new opportunity for the pulp, paper and recycling paper industries. Keywords: fiber-waste-based industry, microalgae-bacteria consortium, removal of nutrients, wastewater treatmen
    corecore