1,720,957 research outputs found
Production of gamma-polyglutamic acid in submerged cultivation in an airlift bioreactor from Bacillus genus bacteria
No full textA biotecnologia está numa posição privilegiada para substituir materiais poluentes e processos químicos por alternativas mais sustentáveis, como por exemplo, o ácido gama-poliglutâmico (y-PGA), um biopolímero de aplicações multifuncionais, que pode ser obtido a partir de materiais considerados subprodutos da indústria, como o farelo de soja, cascas de arroz, glicerol, entre outros compostos ricos em carbono e nitrogênio. Dessa forma, a produção de y-PGA pode ser uma importante aliada das questões ambientais, principalmente para o tratamento de água potável, considerando que não apresenta toxicidade ao ser humano e ao ambiente. Esse biopolímero é um composto natural, solúvel em água e comestível, podendo ser utilizado em diversos tratamentos medicinais incluindo o tratamento de câncer e regeneração de tecidos. É produzido a partir de processos fermentativos por microrganismos do gênero Bacillus, seja por cultivo submerso, semissólido ou em estado sólido. No entanto, para que esse produto seja utilizado em formulações comerciais, é fundamental o melhoramento dos processos de produção bem como de purificação. Apesar da possibilidade de utilizar subprodutos da indústria, o elevado custo da produção de y-PGA ainda restringe sua utilização, principalmente no tratamento de água potável, considerando os métodos tradicionais de tratamento de água utilizados atualmente. Assim, este projeto voltou-se para estudar a aplicação de um biorreator não convencional do tipo airlift e do modo de operação contínua para produção de PGA, avaliando as grandezas de transformação (velocidade específica de crescimento, conversão de substrato em biomassa e produtividade) para duas espécies de Bacillus, B. licheniformis e B. subtilis, com diferentes condições nutricionais. A cinética de crescimento dos bacilos foi estudada em fermentação em batelada com o objetivo de verificar o tempo de conversão dos substratos em biomassa, além de verificar o comportamento geral dos microrganismos. Nos experimentos realizados pode-se observar um tempo de duplicação menor para B. licheniformis. Das fontes de nitrogênio inorgânico utilizadas nesse estudo para obtenção de y-PGA, o composto com melhor aproveitamento no processo foi o sulfato de amônio, que é mais barato tanto em relação a outras fontes inorgânicas como também fontes orgânicas de nitrogênio. Nos experimentos conduzidos para analisar as diferentes fontes de carbono para a produção de γ PGA observou-se em especial a importância em disponibilizar os nutrientes essenciais para produção do biopolímero, os meios suplementados com glicerol apresentaram melhores resultados (P= 1,033 g.L-1.h-1 e YP/S= 0,266 gP.g.subs-1), porém quando em concentrações inferiores à 40 g L-1. A glicose como fonte de carbono também foi importante na produção de γ-PGA, no entanto, observou-se produção de γ-PGA em meio sem glicose, enquanto houve baixa produção quando uma concentração de glicose superior a 15 g L -1 foi adicionada ao meio de cultivo. A adição de 0,3% de n-heptano no início das fermentações como vetor para aumentar a solubilidade de oxigênio no meio de cultivo, foi favorável para o crescimento da biomassa, principalmente para o B. licheniformis, houve aumento também na produção de γ-PGA em comparação aos experimentos sem a adição do solvente orgânico. Os resultados permitiram definir uma composição apropriada para o meio de cultivo, bem como das condições de processo, de modo a obter um rendimento e produtividade maior, com menor custo de operação, considerando ainda a menor geração de resíduos. O rendimento na produção de y-PGA foi ainda melhor no biorreator airlift com alimentação contínua dos nutrientes, utilizando baixas concentrações de carbono e nitrogênio. Dessa forma, a produtividade nessas condições foi de 2,31 g L -1 h -1 com um rendimento de 0,678 (g de biopolímero/g de substrato de carbono), além de baixa produção de resíduos, atendendo com isso os conceitos de sustentabilidade, onde é possível com base em processos biotecnológicos, a obtenção de um produto com alto valor agregado a partir de subprodutos, em processo com custo reduzido e baixo impacto ambiental.Biotechnology is in a privileged position to replace polluting materials and chemical processes with more sustainable alternatives, such as gamma-polyglutamic acid (γ-PGA), a biopolymer with multifunctional applications, which can be obtained from materials considered by-products of industry, such as soybean meal, rice husks, glycerol, among other compounds rich in carbon and nitrogen. Thus, the production of γ-PGA can be an important ally of environmental issues, especially for the treatment of drinking water, considering that it does not present toxicity to humans and the environment. This biopolymer is a natural, water-soluble and edible compound, which can be used in several medicinal treatments, including the treatment of cancer and tissue regeneration. It is produced from fermentation processes by microorganisms of Bacillus genus, either by submerged, semi-solid or solid state cultivation. However, for this product to be used in commercial formulations, it is essential to improve production processes as well as purification. Despite the possibility of using by-products from the industry, the high cost of producing γ-PGA still restricts its use, especially in the treatment of drinking water, considering the traditional methods of water treatment currently used. Thus, this project focused on studying the application of an unconventional airlift bioreactor and continuous operation mode for the production of γ-PGA, evaluated as transformation quantities (specific growth rate, substrate-to-biomass conversion and productivity) for two Bacillus species, licheniformis and subtilis, with different nutritional conditions. The kinetics of growth of bacillus was studied in fermentation in batch with the objective of verifying the time of conversion of substrates into biomass, in addition to verifying the general behavior of microorganisms. In the experiments carried out, it was possible to observe a shorter doubling time for B. licheniformis. Of the inorganic nitrogen sources used in this study to obtain γ-PGA, the compound with the best use in the process was ammonium sulfate, which is cheaper compared to other inorganic sources as well as organic sources of nitrogen. In the experiments conducted to analyze the different carbon sources for the production of γ-PGA, the importance of making essential nutrients available for the production of the biopolymer was observed, the medium supplemented with glycerol showed better results (P= 1.033 g L-1 h-1 and YP/S= 0.266 gP g.subs-1), but when in concentrations below 40 g L-1. Glucose as a carbon source was also important in the production of γ-PGA, however, γ PGA production was observed in a medium without glucose, while there was low production when a glucose concentration greater than 15 g L-1 was added to the medium. cultivation medium. The addition of 0.3% of n-heptane at the beginning of the fermentations as a vector to increase the solubility of oxygen in the culture medium was favorable for the growth of biomass, especially for B. licheniformis, there was also an increase in the production of γ-PGA compared to experiments without the addition of organic solvent. The results made it possible to define an appropriate composition for the culture medium, as well as the process conditions, in order to obtain a higher yield and productivity, with lower operating costs, considering the lower generation of waste. The yield in the production of γ-PGA was even better in the airlift bioreactor with continuous feeding of nutrients, using Low concentrations of carbon and nitrogen. Thus, the productivity under these conditions was 2.31 g L-1 h-1 with a yield of 0.678 (g of biopolymer/g of carbon substrate), in addition to low waste production, thus meeting the concepts of sustainability, where it is possible, based on biotechnological processes, to obtain a product with high added value from by-products, in a process with reduced cost and low environmental impact.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)88882.434500/2019-11686637/201
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Essa floresta é nossa, tudo que nela existe nos pertence: o espaço natural do Vale do Paranhana delimitado a partir da imigração e colonização alemã no Rio Grande do Sul
No full textO presente artigo visa refletir, por meio de registros fotográficos, as atividades escolares que resultavam em passeios pela cidade e em outras cidades do Estado do Rio Grande do Sul. Oportunidade única, na maioria das vezes, para muitos alunos, tendo em vista que grande parte era proveniente de famílias com poucas condições econômicas. As imagens são decorrentes uma pesquisa nos acervos escolares de três instituições de ensino: Escola Estadual de Educação Básica Governador Jorge Lacerda; Escola Estadual de Ensino Fundamental Professor Justino Alberto Tietbohel; Escola de Educação Básica Marcílio Dias. Para tanto, alguns autores contribuem nas respectivas analises, como Susan Sontag, Boris Kossoy, entre outros autores
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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