Abstract The incorporation of natural fibers into polymer matrices poses challenges due to physicochemical incompatibility, which is typically addressed through precursor modification or the use of compatibilizers. Here, we introduce a novel type of composite that overcomes this challenge by utilizing a network of fine, porous cellulosic sheets inter-diffused with a commercial paraffin films. This approach physically adheres the fiber network to the matrix, preserving its structure. Microscopy images confirm the formation of the proposed microstructure, and mechanical testing reveals a gradual increase in modulus and strength with the incorporation of cellulose. The maximum incorporation achieved was 7.6% (w/w) of cellulosic fibers, resulting in a 167% increase (1.67 times improved) in composite stiffness. Moreover, these composites exhibit ductility, with an average deformation of 410 ± 38%, corresponding to 20% reduction in relation to pure matrix. Our findings demonstrate the potential of this approach for developing sustainable materials with improved mechanical properties. incompatibility compatibilizers Here fine interdiffused inter diffused films matrix structure microstructure cellulose 76 7 6 7.6 w/w ww w (w/w 167 1.67 1 67 (1.6 stiffness Moreover ductility 41 38 38% 20 properties 7. 16 1.6 (1. 4 3 2 1. (1 (

Resumo A obra O livro didático de Ciências no Brasil, organizada por Hilário Fracalanza e Jorge Megid Neto, foi publicada em 2006. Mais de 10 anos após sua publicação, algumas de suas proposições precisam ser reanalisadas, dadas as alterações sofridas pelo Programa Nacional do Livro Didático (PNLD), que geraram impacto nos próprios livros. Este trabalho compara enunciados dos capítulos do livro com guias do livro didático produzidos pelo Ministério da Educação, pesquisas sobre o livro didático de ciências e manuais escolares produzidos durante a vigência do PNLD. Em que pesem as desatualizações da obra de Fracalanza e Megid Neto, muitos de seus apontamentos permanecem válidos, embora necessitem ser relativizados à luz das complexas relações enunciativas em que se situam os manuais escolares atualmente.

Abstract More than ten years after the publication of the book “O livro didático de Ciências no Brasil” [The Science textbook in Brazil], edited by Hilário Fracalanza and Jorge Megid Neto, in 2006, some of its propositions require a reanalysis due to changes in the National Textbook Program (PNLD). This paper compares excerpts from the book’s chapters with Didactic Book Guides produced by the Ministry of Education, researches on Science textbooks, and textbooks produced during the term of the PNLD. Despite the outdated assertions in the book of Fracalanza and Megid Neto, many of their statements remain valid until the present days, requiring but a relativization in light of the complex enunciative relations in which school textbooks are currently situated.

Abstract Wood offers a good combination of high strength and low density, but its complete characterization takes a long time. This study aimed to correlate apparent density, chemical component and porosity parameters with the physical and mechanical properties of the wood as an alternative route to reduce the time spent proposing equations to estimate each mechanical property. Ten tropical wood species were characterized in accordance with Brazilian Standards and chemical components were determined by the Klason method, and the porosity using mercury intrusion. Multivariate regression models were applied to the results of each species to find the relationships. Good results were obtained, such as the coefficient of determination and the analysis of variance, which indicated that the equations for 10 out of the 16 properties are significant. Therefore, the apparent density, chemical component and porosity parameters used reduce the time intervals much lower than the time test stipulated by the standard.

Resumo Este trabalho procura realizar um diálogo entre o pensamento do filósofo e educador brasileiro Dermeval Saviani e os estudos sobre a educação em museus e centros de ciências. Primeiramente, investigamos o desenvolvimento histórico dessas instituições para, em seguida, analisarmos, nas obras de Saviani, menções às formas não escolares de educação. A partir dos textos do educador brasileiro, e considerando os diferentes sentidos que a literatura confere às expressões educação informal e educação não formal, propõe-se que as modalidades de educação sejam situadas entre as categorias sistematizada / assistemática e escolar / não escolar. Assim, compreendendo-se a educação museal como uma modalidade de educação não escolar que vem se sistematizando, e a especificidade dos museus frente aos conceitos de conhecimento e cultura, são comentadas algumas possibilidades para que tais instituições colaborem para a democratização do saber, complementando e valorizando a educação científica escolar. Em acordo com a concepção crítica de Saviani, considera-se que os museus e centros de ciências, no estabelecimento de ações educativas, possam contribuir para a elevação da qualidade do ensino de ciências, estabelecendo uma relação comunicativa entre os saberes museais e os saberes escolares. Dessa maneira, não se dissolvem nem a especificidade da instituição museal enquanto guardiã do patrimônio da humanidade, nem a especificidade da escola enquanto transmissora da cultura para as novas gerações.

Abstract This work aims to conduct a dialogue between the thoughts of Brazilian philosopher and educator Dermeval Saviani and studies about education in science museums and centers. Firstly, we investigate the historical development of these institutions, and then analyze mentions to non-school forms of education in Saviani’s works. Based on the writings of this Brazilian educator, and considering the different meanings that the literature assigns to informal education and non-formal education, we propose to situate education modalities between the systematized/unsystematic and school/non-school categories. Thus, by understanding museum education as a modality of non-school education that is becoming systematized, and the specificity of museums concerning the concepts of knowledge and culture, we comment on some possibilities for these institutions to collaborate in making knowledge democratic, thus complementing and valuing school science education. In line with Saviani’s critical position, we consider that, as science museums and centers establish education actions, they could contribute to improve the quality of science teaching by establishing a communicative relationship between museum knowledge and school knowledge. Thus, the specificity of the museum institution as the guardian of human heritage is not dissolved, nor is the specificity of school as the transmitter of culture to new generations.

A polpação organossolve é o processo químico limpo que utiliza solventes orgânicos para remoção de lignina e hemicelulose de matérias-primas lignocelulósicas. Esse método proporciona a facilidade de recuperação do solvente no final do processo. Neste trabalho foi produzida polpa celulósica de bambu pelo processo organossolve, avaliando diferentes temperaturas e tempos de reação, e as polpas foram analisadas visando à futura aplicação para reforço de compósitos. A produção de polpa de bambu pelo processo organossolve foi estudado variando as condições de cozimento de 1, 2 e 3 h a 150, 170 e 190° C, a fim de alcançar as condições ideais de rendimento e características químicas e físicas da polpa para a potencial aplicação em reforço de compósitos. Os melhores resultados para a deslignificação (número de kappa 38), com a degradação da fibra relativamente baixa (viscosidade de 625 cm3 g-1), razão de aspecto de 40,4 e o índice zero span de 204 Nm g-1, foram obtidos pelo processo de polpação a 190°C durante 2h. Essa condição de polpação pode ser considerada como a mais adequada em relação aos demais intervalos de tempo estudados no presente trabalho. A maior resistência mecânica e menor incidência de defeitos morfológicos na fibra (6,0% de curls e de 10,6% de kinks) podem demonstrar o potencial da polpa organossolve bambu como elemento de reforço.

This paper deals with the Brazilian textbooks of Chemistry from the XIX century to 1930. After presenting the science and its teaching contexts in Imperial Brazil and describing the first Chemistry textbook written by a Brazilian, the state of knowledge about these prime Brazilian books is presented. These works show the texts had strengths overlooked by current materials, a fact confirmed by analyzing textbooks from three authors from the period. The study concludes by compiling a list of 50 titles of early Chemistry books to help guide future research.

Investigamos o ensino de Química para os anos iniciais da Educação Básica. Inicialmente, recuperamos resultados de investigações anteriores, constituindo a visão acadêmica sobre o tema. Estes trabalhos, cobrindo quase duas décadas, indicam que a Química ocupa reduzido espaço no currículo do início do Ensino Fundamental, recebendo um tratamento fragmentado por parte dos livros didáticos, e sendo pouco reconhecida pelos docentes como um conteúdo relevante. A seguir, analisamos 182 atividades, propostas pelas 12 coleções de livros aprovadas no Programa Nacional do Livro Didático 2007, classificando-as em categorias que explicitam a importância relegada ao conhecimento químico. Somente duas coleções se enquadram em um perfil desejável para a apresentação destas atividades na progressão pelas séries. Ainda, entre 11 fenômenos químicos diversos, as atividades se concentram em apenas dois. Concluímos sugerindo que estes livros têm contribuído de forma pouco substancial para um adequado ensino elementar de Química.

We investigated the Chemistry teaching to initial years of basic education. Initially, we analyzed the results of previous investigations, which constitute the academic view on the subject. These works, covering almost two decades, indicate that Chemistry occupies little space in the elementary school curriculum, receiving a fragmented treatment by the textbooks and being rarely recognized by teachers as having relevant content. Next, we analyzed 182 activities, proposed by 12 approved collections of textbooks in the Brazilian Program of Textbooks 2007, and classified them into categories that clearly show the importance given to chemical knowledge. Only two collections fit into a desirable profile for the presentation of these activities in the prospectus for schools. Also, among 11 different chemical phenomena, the activities concentrate on just two. We conclude by suggesting that these books have not have contributed substantially to an appropriate elementary Chemistry teaching.

Blends of starch and zein plasticized with glycerol were prepared by melting processing in an intensive batch mixer connected to a torque rheometer at 160 °C. The resulting mixtures were compression molded and then characterized by scanning electron microscopy, differential scanning calorimetry, wide-angle X ray diffraction and water-absorption experiments. The blends were immiscible, showing two distinct phases of starch and zein. The water uptake at equilibrium and its diffusion coefficient were determined. The water uptake at equilibrium decreased with increasing zein content. The diffusion coefficient fell sharply on addition of 20% zein and remained constant as zein content was increased. No appreciable effect of zein on starch crystallization was observed by X ray diffraction. The use of zein in thermoplastic starch compositions causes a decrease in the water sensitivity of these materials and lower its melt viscosity during processing making zein a suitable and very promising component in TPS compositions.

Chemistry is a experimental science and should be taught emphasizing the experimental work at laboratories. Brazilian teachers either in secondary level teaching as well at University gave minor attention in laboratory experiments as a tool to improve the quality of the teaching. Adelino Leal published a monograph in 1926 which emphasizes the experimental work in the teaching of Chemistry. The French chemist Jungfleisch had a important influence in the Adelino Leal's work and was the main reference for both his work and published books.