Silvopastoral agroforestry for rural environment sustainability and valorization of the region of Guarda and Serra da Estrela, Portugal

N/

Analogias e metáforas no ensino de Ciências : aplicações na educação sexual com mulheres negras

Esta pesquisa tem por objetivo verificar como mulheres negras identificam e interpretam analogias e metáforas presentes em cartazes de campanhas institucionais de DST/Aids do Governo Federal do Brasil e contribuir para o Ensino de Ciências, em especial, para a educação sexual. Sugere o uso das analogias e das metáforas como recursos de pesquisa e ensino nessa área. Com esse intuito, optou-se por um estudo exploratório, de caráter etnográfico. Os resultados apontaram para a necessidade de sistematizar o uso desses recursos como ferramentas educacionais a fim de evitar possíveis erros conceituais, dado o caráter interpretativo que eles apresentam. Em contrapartida, o uso adequado possibilita a revisão de conceitos, comportamentos e crenças morais e contribui para desconstrução de mitos, ideologias discriminadoras e tabus

In-vitro release profile of microencapsulated α-tocopherol under simulated gastrointestinal conditions

Alpha-tocopherol, the most common form of Vitamin E in nature, is a well-known antioxidant compound for its effective inhibition of lipid oxidation both in food and biological systems. Additionally, due to its preventive action against reactive oxygen species (ROS), α-tocopherol has been associated with risk decreasing of diseases associated with oxidative stress, such as cardiovascular disease and cancer [1]. The recommended ingestion of Vitamin E varies among the countries and according to criteria such as sex and age. In the USA, the recommended daily allowance (RDA) for an adult is 15 mg/day, whereas in Europe it is 4-15 and 3-12 mg α-tocopherol/day for man and women, respectively. Although α-tocopherol is naturally present in several foods, such as vegetable oils and tree nuts, owing to its antioxidant capacity it is frequently included in food supplements and used in the food industry to extend the shelf-life of several products. Nevertheless, due to α-tocopherol instability and sensitivity towards oxygen and light and its poor aqueous solubility, it is generally administered in the acetate or succinate form. However, these forms are considered to have a lower intestinal absorption compared to α-tocopherol [2]. To overcome these problems, the encapsulation of α-tocopherol in protective matrixes to avoid its oxidation and increase shelf life has been suggested. In fact, during the last years, encapsulation technology has been increasingly important in the food industry as it permits the formation of a physical barrier between the external medium and sensitive core materials, being also used for controlled release of active molecules, formulation stability enhancement, and flavor and taste masking. In this context, it is important to assess α-tocopherol release pattern from microparticles as it can restrain its different applicability. In this work, α-tocopherol microspheres were produced using alginate as a polymeric matrix. This polymer, a linear polysaccharide obtained from brown algae consisting of β-mannuronic acid and α-guluronic acid units, was chosen due to its biocompatibility, biodegradability and non-toxicity. Moreover, it presents a high stability at acidic pH, being easily swollen under mild alkali conditions. Alginate microspheres (ME) loaded with α-tocopherol were produced using a NISCO Var J30 atomization unit, following a previously optimized methodology. The produced microspheres were evaluated for encapsulation efficiency and α-tocopherol release profile by measuring the absorbance at 297 nm using a spectrophotometer. The encapsulation efficiency was calculated both by directly measuring the maximum content released after ME disruption and by quantifying the nonencapsulated α-tocopherol present in the CaCl2 coagulation solution and in the wash solution. α-Tocopherol in-vitro release profiles were determined under simulated gastric (pH 1.2) and intestinal (pH 7.4) media during a period of 24 hours. Additionally, a sample of ME were mixed in gastric media during 1h and then transferred to intestinal media until a total of 24h to simulate gastrointestinal conditions. During the testing period samples of the supernatant were periodically taken to determine the amount of released α-tocopherol. Results evidence a very low % of α-tocopherol release under acidic conditions while an almost complete release is achieved when ME were submitted to simulated intestinal conditions suggesting that the proposed approach can constitute an interesting solution to protect α- tocopherol, allowing for its release in the intestine after ingestion. The next steps in this work in progress will include the evaluation of release profiles of ME added to different food matrices.The authors thank FCT for the financial support LSRE (PEst-C/EQB/LA0020/2011 strategic project).info:eu-repo/semantics/publishedVersio

Study of the encapsulation efficiency and release profiles of alginate microspheres containing α-tocopherol

Vitamin E, a lipophilic natural antioxidant comprising different vitamers (α, β, γ and δ-tocopherols and tocotrianols), is frequently used in food supplements and added in different products, such as foodstuffs and cosmetics, to prevent lipid oxidation processes. Due to solubility and stability issues, α-tocopherol is generally administrated as succinate or acetate derivatives, which have lower bioavailability. In this work, alginate microspheres containing α-tocopherol were produced and evaluated for encapsulation efficiency and release profiles at different pH conditions during 24h. In vitro release tests showed that alginate microspheres maintain its integrity under simulated gastric conditions. By the contrary, under simulated intestinal conditions, an almost complete release is achieved during 24h, with a major portion (70%) being released after 2h.Financial support was provided by FCT and FEDER under Programme COMPETE (Project PEst-C/EQB/LA0020/2013).info:eu-repo/semantics/publishedVersio

Desenvolvimento de um processo de microencapsulação baseado em quitosano para proteção do α-tocoferol

Este trabalho foi realizado no âmbito da unidade curricular de Projeto da Licenciatura em Engenharia Biomédica do Instituto Politécnico de Bragança. Teve como principal objetivo desenvolver um processo de microencapsulação para proteção do α-tocoferol, a principal forma da vitamina E. O α-tocoferol é um antioxidante que possui um papel importante na proteção do organismo contra certos tipos de cancro e do envelhecimento da pele. Contudo, apresenta instabilidade à temperatura, oxigénio e luz, sendo importante a sua microencapsulação para garantir a sua proteção. Os estudos preliminares levados a cabo no âmbito da unidade curricular supramencionada consideram a utilização de duas matrizes poliméricas (quitosano e alginato), optando-se neste trabalho por apresentar os resultados obtidos com o quitosano e na perspetiva do desenvolvimento do processo de microencapsulação. Numa última etapa, o comportamento das microesferas produzidas foi testado para diferentes condições de pH

Chitosan microparticles loaded with essential oils having in view leather applications

Chitosan is a biopolymer attracting considerable attention for diverse applications due to its unique properties like biodegradability, biocompability, non-toxicity and antimicrobial activity. It is obtained by the partial N-deacetylation of chitin, which is the second most abundant polysaccharide in nature, next to cellulose. Chitosan is a viable base material for functional coatings development, namely due to its antimicrobial activity. This characteristic is especially useful for footwear applications that constitute products prone to microbial attack. In this context, developing antimicrobial coatings to be used in footwear components in direct contact with the feet are of great interest, both at industrial level (reducing possibility of material deterioration and quality loss), as well as, from the consumer’s point of view (decrease of skin infections and minor unpleasant odours). Following our previous work, where leather impregnation with chitosan was studied at laboratorial level with quite promising results, and having in view the final application (footwear leather components), where the antimicrobial effect must need to be enhanced, we have developed the idea of microencapsulate different essential oils, with recognized antimicrobial activity like lemon, oregano, eucalyptus and pine. These chitosan-based microparticles, loaded with the chosen essential oil are intended to be applied conjunctly with the chitosan coating process previously studied. Microencapsulation will ensure that the loaded core material will be progressively released, reinforcing the antimicrobial durability and effectiveness of the final product.COMPETE, QREN and EU within the project QREN-ADI-1585-ADVANCEDSHO

Chitosan-based leather functional coatings with improved antimicrobial properties

Among the interesting biological activities that have been ascribed to chitosan, the antimicrobial activity is probably the one that generates the higher number of applications. Developing antimicrobial coatings for footwear components to be used in direct contact with the feet is of great interest; both at industrial level (reducing the possibility of material deterioration and quality loss) and from the consumer’s point of view (decreasing skin infections and minimizing unpleasant odours). One weakness of this application is addressed to the durability and efficiency of the product antimicrobial activity, since it is directly associated with the availability of the positively charged R–NH3 + groups that are depleted during use

Production of chitosan based films enriched with oregano essential oil for increased antibacterial activity

During the last years, there has been an increasing interest in developing bio-based active films to improve food safety, extend food shelf life and reduce the use of chemical preservatives. Chitosan, a deacetylated derivative of chitin, is a linear polysaccharide consisting of -(1 4) glucosamine and N-acetylglucosamine residues with potential to be used as a food packaging/coating material. This biopolymer can be used in a wide range of applications in the food industry due to several interesting properties such as its biodegradability, biocompatibility, non-toxicity, antimicrobial activity and versatile physical properties such as its film-forming capacity. Recently, different strategies have been explored to improve its natural properties for the development of food packaging/coating materials with enhanced antimicrobial activity. In particular, the incorporation in chitosan films of essential oils (EO) with acknowledged antibacterial properties, as an alternative of synthetic preservatives, is a matter of great interest since they are generally perceived by consumers as being “natural” food additives. Thus, the objective of this work was the production of chitosan films enriched with oregano EO to further improve the natural antimicrobial properties of chitosan. The obtained films which were then evaluated for its antibacterial activity

Chitosan as an antimicrobial agent for footwear leather components

In the footwear industry, microorganisms’ growth can pose problems of material deterioration with associated unpleasant smell and generate possible infections in susceptible individuals. Generally, footwear presents high relative humidity conditions that enable the growth of bacteria and fungi. Additionally, leather itself and some tannery agents such as oils and greases, provide a substrate where microorganisms can grow. In the foot, microtraumas caused by ingrown nails, abrasions and lacerations can allow microbial invasion through epidermis, resulting in skin infection. In this work, the applicability of chitosan functional coatings to leather was tested, with the purpose to develop new base materials to produce footwear components. The leather treated with chitosan was then studied for its antibacterial properties against 3 different bacteria.COMPETE, QREN and EU (project QREN-ADI-1585-ADVANCEDSHOE)

The use of bio-based additives (lignin, starch and cellulose) in thermoplastic polyuretane formulations to enhance the biodegradability of footwear components

Thermoplastic polyurethanes (TPUs) are one of the most widely used polymeric materials. They can be used in an extensive range of applications, including automotive, footwear, interior design, adhesives, coatings, textile and biomedical. In what concerns the footwear sector, it is estimated that TPU based components represent about 60% of the whole European production of footwear components [1]. On the other hand, the use of a wide variety of additives in TPU formulations (e.g. pigments, coatings and fillers) limits the possibility of recycling. In such scenario, biodegradable polymers could offer an excellent solution to the environment hazard posed by the conventional materials [2]. Therefore, given the widespread use of TPUs and associated waste management problems, it makes sense to invest on the development of more biodegradable and environmental compatible solutions. For this purpose, the incorporation of bio-based and biodegradable additives is being studied in the last years [2-4]. The incorporation of a biodegradable compound, even at a low content in a TPU formulation, can promote biodegradation. It will constitute a preferential site for microorganisms’ attack thus favouring biodegradation initiation and progression. In this work, a base TPU used in the footwear industry was modified by compounding with three biobased additives (lignin, starch and cellulose). Biodegradability of the resulting materials was evaluated in agar plate tests against the fungi Aspergillus niger ATCC16404, the gram negative bacteria Pseudomonas aeruginosa ATCC9027 and an association of both (consortium). In a second phase soil tests have been also performed.info:eu-repo/semantics/publishedVersio