51 resultados para Olimpiada de Química
Resumo:
Analisa a indexação dos documentos da Biblioteca Setorial de Química através de um estudo informétrico na ferramenta de busca do Sistema de Bibliotecas (SISBI) da Universidade Federal do Rio Grande do Norte (UFRN). Descreve um estudo informétrico realizado na ferramenta de busca do SISBI da UFRN, sendo feita direcionada para os documentos Biblioteca Setorial de Química. Enfoca a importância do estudo informétrico para analisar a recuperação da informação relacionada à indexação. Aborda a relação da informetria com a indexação e recuperação da informação com o intuito de que o profissional bibliotecário seja mais analítico e tenha uma compreensão maior do campo da ciência da informação. Utiliza de uma metodologia de consultas de assuntos pré-definidos, sendo feita uma filtragem de forma quantitativa com o objetivo de verificar se a indexação dos documentos está sendo satisfatória para a recuperação da informação na ferramenta de busca do SISBI. Constata a relevância dos documentos em cada busca sua precisão e revocação, mostrando que para haver uma boa recuperação da informação tem que a indexação seja feita de forma que não haja ambiguidade com outros termos, com isso mostra a importância de sempre ser feito um estudo informétrico com que verifique a recuperação da informação para que possa sempre haver uma melhora na mesma.
Resumo:
The current study examined spatial-temporal modifications and water quality through chemical and biotic indicators during both dry (January, February and November 2006) and wet seasons (March to June 2006). This study was carried out in Armando Ribeiro Gonçalves Reservoir, RN, Canal do Pataxó and after the water station treatment (WST). The physical-chemical parameters were measured in situ and inorganic nutrients, chlorophyll a and Free Oxygen Demand (FOD) were analyzed in laboratory conditions. Quali quantitative analyses of phytoplankton were carried out utilizing Sedgwick-Rafter camera. Results indicate that DQO concentrations were low. FOD concentrations in the reservoir were comparatively higher in the dry season (5.21 mgL-1; 5.64 mgL-1 e 6.05 mgL-1) in relation to the wet season (4.52 mgL-1; 4.12 mgL-1 e 4.92 mgL-1), in surface, intermediate and bottom waters, respectively. FOD values were inferior to 1.0mgL-1in both Canal do Pataxó and after WST, which is considered adequate for public use reservoirs. Although FOD concentrations were low, Armando Ribeiro Gonçalves Reservoir, Canal do Pataxó and WST were classified as euthophizied, mesotrophic ad oligotrophic, respectively, considering the Index of Trophic State Criteria. Chlorophyll a concentrations in the study reservoir were higher in the surface (199.2 µgL-1) during the wet season, whereas in Canal do Pataxó concentrations decreased from 1.56 µgL-1 to 0.028 µgL-1, and after WST values were low (0.059 µgL-1). Dominance of cianobacterias, such as Planktotrhix agardhii (dry season) and Microcystis sp (wet season) was registered in all three areas. In the reservoir and Canal do Pataxó, density of cianobacterias, such as P. agardhii and Microcistys sp., was superior to the values allowed by the Health ministry (HM). However, after WST, density values of cianobacteria were inferior to values established by the HM
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Galactans are polysaccharides sulfated present in the cell wall of red algae. Carrageenans are galactans well known in the food industry as gelling polysaccharides and for induce inflammatory process in rodents as animal model. The extraction of polysaccharides from A. multifida has been carried out by proteolysis and precipitation in different volumes of acetone, which produced three fractions (F1, F2, and FT). Chemical and physical analyses revealed that these fractions are sulfated galactan predominantly. Results of the antioxidant activity assays showed that all of these fractions have antioxidant activity and that was associated with sulfate content of the analysis of reducing power and total antioxidant capacity. However, these fractions were not effective against lipid peroxidation. The fraction FT presented higher activity on the APTT test at 200 μg (> 240 s). The assessment of the hemolytic activity showed that the FT fraction has the best activity, increasing lyses by the complement system to 42.3% (50 μg) (p< 0,001). The fraction FT showed the best yield, anticoagulant and hemolytic activity between the three fractions and therefore it was choose for the in vivo studies. The Inflammation assessment using the FT fraction (50 mg / kg MB) showed that the cellular migration and the IL-6 production increased 670.1% (p< 0,001) and 531.8% (p< 0,001), respectively. These results confirmed its use as an inflammation inducer in animal model. Cytotoxicity assay results showed that all fractions have toxic effects on 3T3 and HeLa cells after exposition of 48 hours, except when 100 μg for both F1 and FT were used. These results arise the discussion whether these polysaccharides it should be used as additive in foods, cosmetics and medicines.
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This study examines the physical and chemical composition and the pharmacological effects of brown seaweed FRF 0.8 Lobophora variegata. Fractionation of the crude extract was done with the concentration of 0.8 volumes of acetone, obtaining the FRF 0.8. The physicochemical characterization showed that it was a fucana sulfated. Anti-inflammatory activity was assessed by paw edema model by the high rates of inhibition of the edema and the best results were in the fourth hour after induction (100 ± 1.4% at the dose of 75 mg / kg) and by the strong inhibitory activity of the enzyme myeloperoxidase (91.45% at the dose of 25 mg / kg). The hepataproteção was demonstrated by measurements of enzymatic and metabolic parameters indicative of liver damage, such as bilirubin (reduction in 68.81%, 70.68% and 68.21% for bilirubin total, direct and indirect, respectively at a dose of 75 mg / kg), ALT, AST and γ-GT (decrease of 76.93%, 44.58% and 50% respectively at a dose of 75 mg / kg) by analysis of histological slides of liver tissue, confirming that hepatoprotective effect the polymers of carbohydrates, showing a reduction in tissue damage caused by CCl4 and the inhibition of the enzyme complex of cytochrome P 450 (increasing sleep time in 54.6% and reducing the latency time in 71.43%). The effectiveness of the FRF 0.8 angiogenesis was examined in chorioallantoic membrane (CAM) of fertilized eggs, with the density of capillaries evaluated and scored, showing an effect proangigênico at all concentrations tested FRF (10 mg- 1000 mg). The FRF showed antioxidant activity on free radicals (by inhibiting Superoxide Radical in 55.62 ± 2.10%, Lipid Peroxidation in 100.15 ± 0.01%, Hydroxyl Radical in 41.84 ± 0.001% and 71.47 Peroxide in ± 2.69% at concentration of 0.62 mg / mL). The anticoagulant activity was observed with prolongation of activated partial thromboplastin time (aPTT) at 50 mg (> 240 s), showing that its action occurs in the intrinsic pathway of the coagulation cascade. Thus, our results indicate that these sulfated polysaccharides are an important pharmacological target
Resumo:
Spondias sp. (Anacardiaceae), popularly known as cajá-umbu, is an endemic plant from Northeastern Brazil, where their leaves are widely used in folk medicine to treat inflammatory processes, while their fruits have a great agro industrial potential. This study was designed to evaluate hepatoprotective, antinociceptive, antioxidant, antimicrobial and anti-inflammatory properties, as well as the acute toxicity and repeated dose 28, using a methanolic extract (MES), a fraction rich in flavonoids (FRF) and a precipitate from Spondias sp.leaves. The antioxidant activity of them was valued to evaluate their free radical scavenger capacity by DPPH test, whereas MES and FRF were used to evaluate while the preventive action on carbon tetrachloride (CCl4)-induced hepatotoxicity. Seven groups (n=5) of female Wistar rats were used as follows: control group, CCl4-intoxicated group treated with EMS (500 mg/kg) for 7 days, three CCl4-intoxicated groups treated with FRF (25, 50 and 75 mg/kg) for 7 days and the CCl4-intoxicated group treated with Legalon ® (silimarina; (phytotherapeutic reference) (50 mg/kg; 7 days). MES and FRF showed a protective action against liver injury induced by CCl4, being observed a significant reduction of serum enzyme activity marker of liver damage (alanine transaminase and aspartate transaminase). On the other hand, the lipid peroxidation (SRAT) decrease, as well as the increase of glutathione content and enzyme activity of antioxidant defense system (SOD, CAT, GPx) toward near normal values indicated the ability of EMS to restore the oxidative imbalance induced by CCl4. The histological analysis confirmed the hepatoprotection, compared to degenerative changes in CCl4-treated group. This hepatoprotetor effect was similar to that shown by Legalon®. The in vitro high antioxidant capacity of extract (93.16 ± 1.00%) showed analogous results to those obtained by Carduus marianus BHT (reference standard). This fact explains the obtained results in vivo. Although no antimicrobial activity was detected, EMS and FRF promoted the antinociceptive effect induced in the second phase by the intraplantar formalin test, evidencing the anti-inflammatory action; confirmed by the carrageenan-induced peritonitis model. The evaluation of the mechanical allodynia (CFA a 80%) demonstrated the involvement of the Spondias sp. chemical composition in the anti-inflammatory activity toward the acute processes. The acute exposure and repeated dose during 28 days did not produce significant changes in the parameters that evaluate toxicity. Together the experimental results reveal, that Spondias sp. leaf extracts have a promising potential in pharmaceutical area, and due to its non-toxic condition present efficiency and security
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In the past twenty years, there has been a significant increase of researches about teacher s professionalization. In that context, the investigations concerning teacher s knowledge represent an important contribution, as they aim to identify and to rescue the base of knowledge that sustains the teacher s profession. In particular, the reflections and propositions of Lee Shulman have been constitute a fundamental subsidy to the teacher s professionalization in the sense of harnessing the pedagogic knowledge to the content s knowledge, establishing the pedagogic knowledge of the content that characterizes and differentiates the teacher and the bachelor in a certain field of knowledge. Among the indispensable knowledge for the Chemistry teacher's professional practice, in this research we have pointed out the pertinence of the knowledge on the use of models in Chemistry classes in the middle and high school. Those knowledges regard the comprehension of students concerning the understanding and models elaborated in science and the models implemented in the Chemistry teaching, as well as the abilities to plan didactic situations that use models. In this research, we aimed to identify the contributions and barriers during the Chemistry teacher education, in UFRN, in relation to the construction of knowledge that subsidize training teachers in the elaboration of teaching activities that involve the use of models. The investigation was accomplished in UFRN, in the Course of Degree in Chemistry, along with 13 student teachers that studied the subject Practice of Chemistry Teaching. For this research, the following instruments were used: questionnaires with open and closed questions, elaboration of a plan of activities for the Chemistry teaching and an interview to answer the established study s questions. The data was analyzed in an established criteria, classified and tabled. The results showed that the student teachers representations regarding scientific knowledge contemplated, among other topics, the idea of a method for his/her construction. In some cases, the models role was emphasized in that construction, as well as the social dimension in the validation of that knowledge. The scientific models were highlighted by most of the student teachers, as a representation method to explain, understand and interpret the chemical phenomena. On the other hand, the didactic models stood out, in most of cases, as a method of aiding the Chemistry students of the Basic Education to understand the scientific models. The representations regarding those categories contemplated important aspects, although in a superficial way, reflecting the limitations of reflections during the formative process. In the elaboration of teaching activities that use models, difficulties were evidenced, in the process of plan construction, relative to the didactic structure and to the proposition of activities that contemplated models, although the student teachers have mobilized different elements regarding the pedagogic knowledge of the content. Such verifications evidence the urge for the teacher development programs to promote changes in the teacher education in order to propitiate, during this process, reflections, discussions and propositions of activities regarding categories highlighted in this research, contributing to the construction of initial elements regarding the pedagogic knowledge of the content that will be developed throughout teaching, therefore corroborating to the teacher s professionalization
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The purpose of this work is to approach and understand the Social Representations (SR) (MOSCOVICI, 2003) about Physics and Chemistry from people who are major in these courses, as well as their Social Representations about teaching . We took as principle that approaching these representations it would be possible to relate their symbolic contents, in order to show how people who are following the first segments of bachelor degree courses in Physics and Chemistry become teachers, taking into account a psychosocial view. Two source of data was used during this research: Free-association Technique FA (ABRIC, 1994); and Multiple Classification Procedure (MCP) (ROAZZI, 1995). The analytical treatment of the collected data from FA was done according to the proposition of Grize, Vergés and Silem (1987 apud ABRIC, 1994, p. 66). MCP data were analyzed through MSA (Multidimensional Scalogram Analysis) and SSA (Singular Spectrum Analysis) methods associated with the Facet Theory (BILSKY, 2003). The discourses of MCP discussing groups at the moment of explanations were studied by Content Analysis as it was proposed by Bardin (1977) and Franco (2005). Indicative of an approach to the relations with knowledge (CHARLOT, 2000), the connections which aroused from the analyses showed that the group of future majors in Physics thought that this scientific field was based on a rationalist conception, influencing the idealization sense of the phenomena to be explained by Physics. Thus, Physics as school content started to require the student of the fundamental and high school to think abstractly as a cognitive skill of learning. The identifying elements observed in the relations between SR about Physics and Teaching aroused from the antagonism between future majors and their teacher, as well as from the speculation between their fundamental and high school students and themselves, mainly when they had to face the act of teaching due to the obstacles imposed by the own educational system, and by the weakness of the initial preparation. The group of future majors in Chemistry, through its discourses, showed these relations when they conceived empiricist Chemistry and said that teaching was the way of transmission of this knowledge, and didactics of Chemistry teaching was the direction to learning through pedagogic methods in order to lead the students to discoveries. The psychosocial contents which were built and showed from the symbolic relations in the studied SR achieved the relation of identity. This relation revealed identifying elements for these people, resulting from the traffic between their condition as students of Chemistry, and as teachers regarding their work, what placed the current relational contents in the teaching space, named as Knowledge changing and Adaptability . In order to study emerging questions in the discussing environment about formation and teaching professionalization, we focused the psychosocial view on this traffic and managed to observe epistemological practical and pedagogic obstacles that limited a configuration of the teaching work as a professional activity, especially from the particular conditions which led the relations of senses to Physics , Chemistry and Teaching ; and Chemistry and Physics as it was seen in this research. Generally speaking, we noted that these obstacles can denounce such obstacles concerning to the pedagogic doings which mainly impair the learning process of fundamental and high school students
Resumo:
Esta disertación es el resultado de un estudio de naturaleza de calidad que tuvo como objetivo analizar la estructura curricular de los cursos de Licenciatura en Física y en Química de Universidad Federal de Rio Grande del Norte en lo que se refiere a la inserción de disciplinas de contenido histórico y filosófico. La metodologia adoptada se constituye en un estudio de caso comparativo, pues procura establecer relaciones entre los dos cursos analizados. En este sentido, fueron consultados, para cada uno de los dos cursos, el Proyecto Político Pedagógico, el programa de La Disiplina y los materiales en ella utilizados. Se realizó también, la observación simple de clases de la disciplina y en seguida, una entrevista semi-estructurada con el profesor responsable por ella. Los resultados muestran que las disciplinas están inseridas en los currículos de los cursos de Física y de Química de maneras diferentes, principalmente en lo que se refiere a los enfoques teóricos-metodológicos asumidos por los profesores en el trabajo con los contenidos y en lo que se dice al respecto del papel desempeñado por la disciplina en la estructuta curricular. Hay por otro lado, puntos de convergencia, notadamente cuanto a la formación y al histórico de los profesores formadores, asi como en la relación a los modelos de formación subyacentes a la estructura curricular de los cursos. Se concluye que el conocimineto mútuo de los diferentes modelos de inserción de disciplinas de contenido histórico y filosófico en las Licenciaturas en Física y en Química de La UFRN podría contribuir para futuras reformulaciones curriculares, en el sentido del establecimiento de opciones claras y concientes acerca del papel a ser desempeñado por esas disciplinas en los cursos
Resumo:
It has been remarkable among the Science Teaching debates the necessity that students do not learn only theories, laws and concepts, but also develop skills which allows them to act towards a critical citizenship. Therefore, some of the skills for the natural sciences learning must be taught consciously, intentionally and in a planned way, as component of a basic competence. Studies of the last twenty years have shown that students and teachers have plenty of difficulties about skills development and, among several, the skill of interpreting Cartesian graphics, essential for the comprehension of Natural Science. In that sense, the development of that type of professional knowledge during the initial education of future Chemistry teachers has become strategic, not only because they need to know how to use it, but also because they need to know how to teach it. This research has as its general objective the organization, development and study of a process of formation of the skill of interpreting Cartesian graphics as part of the teachers professional knowledge. It has been accomplished through a formative experience with six undergraduate students of the Teaching Degree Course of Chemistry of Universidade Federal do Rio Grande do Norte (UFRN Federal University of Rio Grande do Norte), in Brazil. In order to develop that skill, we have used as reference P. Ya. Galperin s Theory of the Stepwise Formation of Mental Actions and Concepts and its following qualitative indicators: action form, degree of generalization, degree of consciousness, degree of independence and degree of solidness. The research, in a qualitative approach, has prioritized as instruments of data collecting the registering of the activities of the undergraduate students, the observation, the questionnaire and the diagnosis tests. At the first moment, a teaching framework has been planned for the development of the skill of interpreting Cartesian graphics based on the presupposed conceptions and steps of Galperin s Theory. At the second moment, the referred framework has been applied and the process of the skill formation has been studied. The results have shown the possibility of develop the skill conscious about the invariant operation system, with a high degree of generalization and internalized the operational invariant in the mental plane. The students have attested the contributions at that type of formative experience. The research reveals the importance of going deeper about the teaching comprehension of the individualities tied to the process of internalization, according to Galperin s Theory, when the update of abilities as part of the teaching professional knowledge is the issue
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This research aims to understand the social representations Teaching Work in groups of undergraduate students of Physics and Chemistry of the Federal University of Rio Grande do Norte. For this, the proposal was based on the three theoretical and methodological consensus Carvalho (2012) in the explanation of socio-genetic mechanisms constituents of dynamic consensus that has functionality to your organization. It Was used to achieve this goal, the theoretical-epistemological Serge Moscovici (1978, 2003), Jodelet (2011), Wagner (1998,( 2011) and Carvalho (2012). The corpus analyzed results from a qualitative and quantitative research, developed in three stages. The first two (2) questionnaires to fifty (50) of each undergraduate course, a questionnaire and another profile for collection of free associations concerning motes inductors "Give Lesson," "Student" and "Teacher". The second step in the procedure Multiple Classifications, Roazzi (1995), aimed for another thirty (30) undergraduate students for each course, as well as Document Analysis of Educational Projects Curriculum courses in Physics and Chemistry. The data analysis of the first stage focused on descriptive statistics and frequency and average order of the words associated with motes inductors. The results from the Multiple Classification Procedure submitted to multidimensional analysis (MSA multidimensional scalogram analysis) and SSA (Similarity Structure Analysis), were interpreted by the theoretical and methodological proposal of the three consensus, supported by analysis of the rhetorical nature of justifications classifications and categorizations of words, boosted in times of application of Procedure Multiple Classification. The data revealed that the groups surveyed were the same Social Representation with specific dynamic consensual. Thinking Teaching Work for these groups it is considered in three dimensions: the BE-DO-HAVE of teaching. In the group of Physics consensus was clear semantic, which expressed a dynamic in which the interpretations of "Teaching Work" peacefully coexist on perceptions of two concepts: An identity around the "BE" "Teacher" or "BE" "Educator" and the other, how they think about professional development. The type of group consensus Chemistry pointed to a consensual logic hierarchical order in which the gradual between the elements of BE-DO-HAVE attested conflicts and disagreements about the perceptual object "Teaching Work", around what value most, whether they are the attributes of personal or professional-technical dimension of teaching, in the course of professional development. The thesis to explain the mechanisms of socio-genetic Representation Social Teaching Work by theoretical and methodological proposal was confirmed
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Milk from different animals can be used for dairy production. Yoghurt is a popular fermented milk product and considered to be one of the greatest importance in terms of consumer acceptance and consumption. The present research deals with the production of strawberry set-type yoghurt by mixing goat and buffalo s milk and it has the objective of taking advantage of the intrinsic characteristics of each milk to produce a final product with desirable attributes. It was conducted by analyzing five experimental groups with different proportions of goat and buffalo s milk: C 100% goat s milk; 7C3B - 70% goat s milk and 30% buffalo s milk, 5C5B - 50% goat s milk and 50% buffalo s milk, 3C7B 30% goat s milk and 70% buffalo s milk; B - 100% buffalo s milk. Each group was evaluated for total solids content and the acidification profile was monitored every 30 minutes by pH analysis. The yoghurt samples were analyzed for physical-chemical (pH, acidity, protein, fat, total and reducing sugars, ash and total solids), rheological (syneresis and viscosity) and sensory characteristics (appearance, odor, consistency and flavour). Samples with higher percentual of bubaline milk reached Vm faster, but the time necessary for pH 4.6 (Te) were similar between groups. Statistical differences (p<0.05) were observed for fat and total solids content of yoghurt, with superior values for groups higher proportions of buffalo s milk. The parameters of behavior reached by the model of Ostwald of Waale pointed yoghurt samples as non-Newtonian and pseudoplastic fluids. Yoghurt made only with goat s milk (C) had higher values (p<0.05) for syneresis, which can be explained by its fragile coagulum. Additionally, this group also had the lowest sensory scores for the attributes consistence and taste, while bubaline yoghurt (B) obtained the best acceptance indexes for all of the appraised parameters
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Algaroba (Prosopis juliflora) is a typical legume from arid and semi arid regions, which is composed by sugar-rich pods and high protein seeds. Phenolic compounds are secondary metabolites recognized as potent bioactive compounds, found in several vegetables.Therefore, the objective of this work is to characterize the algaroba flour in terms of its physicalchemical composition, total phenolic content, antioxidant activity by DPPH and ABTS methods, a-amylase and a-glycosidase inhibition, as well as to analyze its organic compounds by high performance liquid chromatography (HPLC). Three experimental groups were investigated (seeds, seeds and pod together and only pod), which were prepared by oven drying and posterior grinding. Water and ethanol extracts (70, 80, 100% v/v) were prepared and used for functional studies. Organic compounds were detected by using HPLC equipment coupled to mass spectrometer. Results show important physical-chemical differences among the experimental groups, seeds, seeds and pod together and only pod. The algarroba seed flour is high in protein (49.49%) and fat (3.10%), while the pod flour is especially rich in sugar (60.3% to 67.9%). Algaroba phenolics are concentrated in pod flour, mainly in water extracts (1.30 mg GAEQ/100g sample). All seed extracts showed high DPPH activity and maximum antioxidant activity was registered for ethanol 80% extracts (19.81 μM Trolox/g sample). The ABTS activity ranged from 9.73 to 12.74 μM Trolox/g sample. Nearly all the extracts were able to inhibit α-amylase activity mildly (30.50% to 48.80%), while the maximum α-glycosidase inhibition was observed for pod water extracts (81.03%). Algaroba water extracts proven to be especially rich in organic compounds, observed by the high number of chromatographic peaks. Results demonstrate that algaroba is a potential candidate for further investigations concerning its possible functional applications
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Despite the relatively organized cashew (Anacardium occidentale L.) productive chain and the number of cashew derivatives found in the market, it is estimated that over 90% of the cashew peduncle is wasted. A possible strategy for a better commercial exploitation of this agroindustrial commodity would be the production of spray dried cashew pulp. Thus, this paper approaches the yellow cashew pulp spray drying process and the final product evaluation. Based on that, the shelf life of the spray dried cashew pulp packed in different packaging was evaluated. Drying was conducted in two drying temperatures (140 °C to 150 °C) and two concentrations of Arabic gum (AG, 15% and 25%), which summed four experimental groups. The drying performance was evaluated as well as the physicochemical characteristics (moisture, water activity, total soluble solids, pH, density, solubility, particle diameter, hygroscopicity, degree of caking, color, scanning electronic microscopy and X-ray diffraction), composition (protein, ash, fat and sugars) and bioactive and functional value (total phenolic compounds, carotenoids, ascorbic acid and antioxidant activity) of the final products. Results showed spray drying efficiency higher than 65% for all experiments, mainly for the C4 group (150 °C and 25% AG) which reached efficiency of 93.4%. It was also observed high solubility (94.7% to 97.9%) and the groups with lower hygroscopicity (5.8% and 6.5%) were those with the highest proportion of drying coadjuvant. The particle diameters ranged between 14.7 μm and 30.2 μm and increased with the proportion of AG. When comparing the product before and after spray drying, the drying impact was evident. However, despite the observed losses, dried yellow cashew showed high phenolic concentration (from 235.9 to 380.4 mg GAE eq / 100 g DM), carotenoids between 0.22 and 0.49 mg/100 g DM and remarkable ascorbic acid levels (852.4 to 1346.2 mg/100 g DM), in addition to antioxidant activity ranging from 12.9 to 16.4 μmol TE/ g DM. The shelf life study revealed decreased phenolic content over time associated to a slight water activity increase. Overall, our results unveil the technological and bioactive potential of dried yellow cashew as a functional ingredient to be used in food formulations or as a ready-to-use product. The technological approach presented here can serve as an efficient strategy for a rational use of the cashew apple, avoiding its current underutilization
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The aim of the present study was to extract vegetable oil from brown linseed (Linum usitatissimum L.), determine fatty acid levels, the antioxidant capacity of the extracted oil and perform a rapid economic assessment of the SFE process in the manufacture of oil. The experiments were conducted in a test bench extractor capable of operating with carbon dioxide and co-solvents, obeying 23 factorial planning with central point in triplicate, and having process yield as response variable and pressure, temperature and percentage of cosolvent as independent variables. The yield (mass of extracted oil/mass of raw material used) ranged from 2.2% to 28.8%, with the best results obtained at 250 bar and 50ºC, using 5% (v/v) ethanol co-solvent. The influence of the variables on extraction kinetics and on the composition of the linseed oil obtained was investigated. The extraction kinetic curves obtained were based on different mathematical models available in the literature. The Martínez et al. (2003) model and the Simple Single Plate (SSP) model discussed by Gaspar et al. (2003) represented the experimental data with the lowest mean square errors (MSE). A manufacturing cost of US$17.85/kgoil was estimated for the production of linseed oil using TECANALYSIS software and the Rosa and Meireles method (2005). To establish comparisons with SFE, conventional extraction tests were conducted with a Soxhlet device using petroleum ether. These tests obtained mean yields of 35.2% for an extraction time of 5h. All the oil samples were sterilized and characterized in terms of their composition in fatty acids (FA) using gas chromatography. The main fatty acids detected were: palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2n-6) and α-linolenic (C18:3n-3). The FA contents obtained with Soxhlet dif ered from those obtained with SFE, with higher percentages of saturated and monounsaturated FA with the Soxhlet technique using petroleum ether. With respect to α-linolenic content (main component of linseed oil) in the samples, SFE performed better than Soxhlet extraction, obtaining percentages between 51.18% and 52.71%, whereas with Soxhlet extraction it was 47.84%. The antioxidant activity of the oil was assessed in the β-carotene/linoleic acid system. The percentages of inhibition of the oxidative process reached 22.11% for the SFE oil, but only 6.09% for commercial oil (cold pressing), suggesting that the SFE technique better preserves the phenolic compounds present in the seed, which are likely responsible for the antioxidant nature of the oil. In vitro tests with the sample displaying the best antioxidant response were conducted in rat liver homogenate to investigate the inhibition of spontaneous lipid peroxidation or autooxidation of biological tissue. Linseed oil proved to be more efficient than fish oil (used as standard) in decreasing lipid peroxidation in the liver tissue of Wistar rats, yielding similar results to those obtained with the use of BHT (synthetic antioxidant). Inhibitory capacity may be explained by the presence of phenolic compounds with antioxidant activity in the linseed oil. The results obtained indicate the need for more detailed studies, given the importance of linseed oil as one of the greatest sources of ω3 among vegetable oils
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Nowadays there are many reasons that aim to include people with special necessities, like those with visual deficiency, in the world of work, education, and in the society as a whole. However it is observed that when we talk about schooling inclusion, especially in High School, there is a huge gap between the theory and the practice. The lack of didactic resources, the inadequate installations, unprepared teachers, the families´ lack of information, are some of the factors that hinder the process of inclusion. Furthermore, the educators also have to deal with the roughness of the disciplinary contents and, refering to the study of Chemistry, with the use of signals related to this subject´s language. So, the objective of our research is to reflect about the apprehension of this language by the visually handicapped people, and try to contribute with their process of inclusion in the school life. On this perspective we work with the Periodic Table, which constitutes one of the indispensable tools necessary to the Chemistry learning. In order to acomplish it, the way followed by us happened in three passages. Initially, by means of a semistructured interview, we tried to get acquainted with the blind students opinion, who were participating in the research about the Periodic Table used by them throughout High School, as well as the dificulties felt when using it. After getting the answers, the Table was reelaborated to fill those students´necessities. Here, two new Tables were designed, one in Braille which shape is more compacted, and another made with high printed dots, built with sand and glue. On the third moment, the new designed Tables were tested by the students and, by means of a semi-structured interview, we tried to identify if this new resource would solve the problems concerned to the old Table. The students showed that the compacted Tables would facilitate the touch reading of the chemical elements simbols, making it clear and fast. We hope that, with the elaboration of this learning tools we can contribute with one of the elements to favor the effective participation of blind students in Chemistry classes, when studying the Periodic Table