• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 175
  • 11
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 201
  • 115
  • 57
  • 44
  • 40
  • 36
  • 32
  • 32
  • 29
  • 29
  • 23
  • 22
  • 21
  • 21
  • 20
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

ObtenÃÃo de oligosscarÃdeos prebiÃticos por processo fermentativo a partir do suco de caju clarificado in natura / Obtentioin of prebiotic oligosaccharides for fermentative process from the clarificado cashew juice in natura

Clarice Maria AraÃjo Chagas Vergara 27 March 2007 (has links)
OligossacarÃdeos prebiÃticos sÃo carboidratos capazes de chegar ao intestino grosso onde sÃo metabolizados pelas bidifidobactÃrias e lactobacilos ali presentes estimulando o seu crescimento. A importÃncia destes microrganismos està associada a sua relaÃÃo com a melhoria da intolerÃncia à lactose, melhora da funÃÃo intestinal, melhoria do sistema imunolÃgico, reduÃÃo de enzimas mutagÃnicas e sÃntese de vitaminas do complexo B. A enzima dextrana-sacarase pode ser facilmente obtida a partir da fermentaÃÃo do Leuconostoc mesenteroides em meio contendo sacarose como fonte de carbono. Esta enzima catalisa a formaÃÃo de dextrana em meio contendo sacarose como Ãnico substrato. Quando um aceptor està presente no meio de cultura, parte das unidades de glicose da sacarose sÃo desviadas da sÃntese de dextrana formando oligossacarÃdeos. A utilizaÃÃo do suco de caju, rico em glicose e frutose, visa o aproveitamento de excedentes agrÃcolas, reduzindo assim o custo do processo final. Este trabalho teve por objetivo estudar a sÃntese de oligossacarÃdeos prebiÃticos a partir da fermentaÃÃo de duas linhagens de Leuconostoc mesenteroides; B512F e B742, ambas nÃo patogÃnicas e seguras do ponto de vista alimentar. Com base nos resultados obtidos pode-se concluir que o processo fermentativo utilizando o suco de caju como substrato apresentou bons resultados, principalmente no que se refere ao crescimento microbiano, produÃÃo da enzima dextrana-sacarase e crescimento de Lactobacillus sendo sua utilizaÃÃo, portanto viÃvel. / Prebiotic oligosaccharides are carbohydrates able to reach the large intestine being metabolizated by bidifidobacterium and lactobacillus and stimulating their growth. The importance of these microorganisms is related with its improvement of the intolerance to the lactose, improvement of the intestinal function and the imunologic system, mutagenic enzyme reduction and vitamin synthesis of the complex B. The enzyme dextransucrase can be easily obtained through the fermentation of Leuconostoc mesenteroides in a medium containing sucrose as carbon source. This enzyme catalyzes the formation of dextran in a medium containing sucrose as the only substrate. When an acceptor is present in the culture medium, part of the glucose moieties from sucrose are deviated from the dextran synthesis forming prebiotic oligosaccharides. The use of the cashew juice, rich in glucose and fructose, aims to the use of an agriculture excess, reducing the cost of the final process. This work had as objective the study of synthesis of prebiotic oligosaccharides from the fermentation of Leuconostoc mesenteroides, B512F and B742, both non pathogenic and safe from the alimentary point of view. Based on the obtained results it can be concluded that the fermentative process using the cashew juice as substratum presented good results, mainly for the microbial growth, production of the enzyme dextransucrase and growth of Lactobacillus being its use, therefore viable.
142

Qualidade e atividade antioxidante total de pedÃnculos de clones comerciais de cajueiro anÃo precoce / Quality and activity total antioxidant capacity of penduncles of commercial grain stalks of clones of dwarf cashew apple tree.

Cyntia Rafaelle Amaral de Abreu 03 August 2007 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / A cajucultura tem grande importancia na fruticultura brasileira, principalmente para o Nordeste, pois representa uma atividade economica e social de grande expressao nessa regiao. Conforme estudos ja realizados, o pedunculo do cajueiro e rico em vitamina C, carotenoides e compostos fenolicos. Alem do potencial vitaminico, estes compostos conferem potencial antioxidante a polpa do caju. Com isso, esse experimento objetivou avaliar a qualidade e a atividade antioxidante total de pedunculos de diferentes clones comerciais de cajueiro anÃo precoce desenvolvidos pela Embrapa Agroindustria Tropical, destinados ao comercio in natura e a industria de transformacao, atraves da caracterizacao fisica, quimica e fisicoquimica, selecionando os clones que apresentaram os melhores resultados. Foram escolhidos dez clones, provenientes da Estacao Experimental da Embrapa Agroindustria Tropical, localizada no municipio de Pacajus - CE: CCP 76, CCP 06, CCP 09, CCP 1001, BRS 189, BRS 226, BRS 265, BRS Bahia 12, Embrapa 50 e Embrapa 51. Sendo caracterizados quanto a: peso, tamanho, coloracao, firmeza, pH, solidos soluveis (SS), acidez titulavel (AT), SS/AT, acucares soluveis totais (AST), vitamina C, antocianinas totais, flavonoides amarelos, carotenoides totais, taninos condensados (TC), polifenois extraiveis totais (PET) e atividade antioxidante total (AAT). Os pedunculos de cajueiro mostraram boa qualidade, de acordo com os atributos avaliados, apresentando uma variacao entre os clones, que so nao foi verificada na variavel pH, onde nao houve diferenca estatistica significativa (p<0,05), entre os tratamentos. Os clones que mais se destacaram foram o BRS 189 e o BRS Bahia 12, o primeiro, por apresentar boas caracteristicas fisicas, como a melhor firmeza, coloracao mais atrativa, alem de ser uma boa fonte de compostos bioativos como vitamina C, antocianinas totais e carotenoides totais, apresentando os maiores valores desses componentes. E o segundo, por possuir tambem uma boa firmeza e ser uma boa fonte de vitamina C e principalmente, por ser uma excelente fonte de polifenois e apresentar a maior atividade antioxidante total, dentre os clones avaliados. Palavras-chave: caju, clones, qualidade, compostos bioativos, atividade antioxidante total. / Cashew has big importance in Brazilian culture of fruits, principally in Northwest region, presenting very expressive social and economic activity. Accordingly to some studies cashew apple has a high vitamin C, carotenoids and phenolics compounds contents. More than vitaminic potential, these compounds have antioxidant potential to cashew pulps. This work aimed at to evaluate the quality and the antioxidant capacity of peduncles from different commercials clones of early dwarf cashew apple tree, developed by Embrapa Agroindustria Tropical, destinated to in natura market and transformation industry, through of physical, chemistry and physical-chemical characterization, selecting the clones that presenting the best results. Ten clones, from Experimental Station of Embrapa Agroindustria Tropical, located in municipality of Pacajus-Ceara, were harvested: CCP-76, CCP-06, CCP-09, CCP-1001, BRS- 189, BRS-226, BRS-265, BRS Bahia 12, Embrapa 50 and Embrapa 51. The clones were characterized to: weight, length, color, firmness, pH, soluble solids (SS), total acidity (TA), SS/TA, total soluble sugars (TSS), vitamin C, anthocianins, yellow flavonoids, total carotenoids, condensed tannins (CT), total extractable polyphenols (TEP) and total antioxidant capacity (TAC). The peduncle presented high quality, according with the evaluated attributes, presenting raised variation between the clones, donât being verified on pH parameter, without significative statistical difference (p<0,05), between the treatments. The most detachable clones were BRS 189 and BRS Bahia 12. The first one presented good physical characteristics like the firmness, the most attractive color, being a high source of bioactive compounds like vitamin C, total anthocianins and total carotenoids, presenting the highest values in these compounds. The second one has a good texture and is a high source of vitamin C and is a excellent source of polyphenols and presenting the most value of total antioxidant capacity, between the evaluated clones. Keywords: cashew, clones, quality, bioactivies compounds, total antioxidant capacity
143

AnÃlise da competitividade da amÃndoa de castanha de caju brasileira no mercado internacional no perÃodo de 1990 a 2007

Daniele Passos de Lima Albuquerque 30 July 2010 (has links)
In the last two decades, Brazil has been losing international market share of cashew nuts (ACC). Given this situation and the economic importance of the product to the state of Ceara, this article aims to analyze the competitiveness of exports of cashew nuts in Brazil during the period of 1990 to 2007. The methodology involves an assessment of the indicators of Revealed Comparative Advantage (VCR), Coverage Rate (CR), export performance (DES), relative position in the market (POS) and the model constant market share (CMS). The indicators analysis was supplemented with the identification of worldwide leading importers and exporters of ACC, verifying opportunities in new markets for Brazil, besides the possible factors influencing the export performance of this. The results of the indicators of Revealed Comparative Advantage and Rate of coverage indicated that Brazil is losing competitiveness in the period analyzed, especially in relation to its two main competitors Vietnam and India, but also presents opportunity for trade expansion of ACC. The Export Performance indicator shows that, for the base year of 1990, there was loss of participation in four of the five main countries of destination. As a result, in three of these destinations, the Brazilian situation is vulnerable, because although still considered competitive, is losing participation in those markets whose demands for ACC are stable or dynamic. The indicator of Relative Position in the Market identified as surplus, Vietnam, India and Brazil, throughout the period of analysis, however, only the first was able to increase his net contribution of trade balance. For the indicator model Constant Market Share (CMS) has defined four sub-periods of analysis, but it was observed between 1990 and 2007, the growth of Brazilian exports of ACC is largely derived from the growth of world trade, because effects destination for exports and competitiveness effects were limiting the growth of exports, despite their positive contributions in some sub-periods. The results of the competitiveness indicators analyzed indicate that even with an increase in Brazilian exports of ACC, Brazil has been losing external competitiveness, given the slow evolution of its exports to the front of its main competitors. / Nas duas Ãltimas dÃcadas, o Brasil vem perdendo participaÃÃo no mercado internacional de amÃndoa de castanha de caju. Diante desse quadro e da importÃncia econÃmica desse produto para o Estado do CearÃ, busca-se analisar a competitividade das exportaÃÃes da amÃndoa de castanha de caju brasileira no perÃodo de 1990 a 2007. A metodologia utilizada compreende a anÃlise dos indicadores de vantagem comparativa revelada (VCR), taxa de cobertura (TC), desempenho das exportaÃÃes (DES), posiÃÃo relativa no mercado (POS) e modelo constant market share (CMS). A anÃlise por indicadores foi complementada com a identificaÃÃo dos principais importadores e exportadores mundiais de ACC, verificando oportunidades de novos mercados para o Brasil, alÃm dos possÃveis fatores influenciadores do desempenho exportador deste. Os resultados dos indicadores de Vantagem Comparativa Revelada e Taxa de Cobertura indicaram que o Brasil vem perdendo competitividade no perÃodo analisado, principalmente em relaÃÃo aos seus dois principais concorrentes, Vietnà e Ãndia, mas ainda apresenta possibilidade de expansÃo comercial da ACC. O indicador de Desempenho das ExportaÃÃes revela que, em relaÃÃo ao ano base de 1990, houve perda de participaÃÃo em quatro dos seus cinco principais paÃses de destino, na maioria dos anos do perÃodo. Em decorrÃncia disso, para trÃs desses destinos a situaÃÃo brasileira à de vulnerabilidade, pois apesar de ainda ser considerado competitivo, vem perdendo participaÃÃo nesses mercados cujas demandas por ACC sÃo estÃveis ou dinÃmicas. O indicador de PosiÃÃo Relativa no Mercado identifica como superavitÃrios, o VietnÃ, a Ãndia e o Brasil, em todo o perÃodo de anÃlise, entretanto, somente o primeiro conseguiu aumentar a contribuiÃÃo lÃquida de seu saldo comercial. Para o indicador modelo Constant Market Share (CMS) foram definidos quatro sub-perÃodos de anÃlise, mas observou-se, entre 1990 e 2007, que o crescimento das exportaÃÃes brasileiras de ACC à em grande parte derivado do crescimento do comÃrcio mundial, pois os efeitos destino das exportaÃÃes e efeito competitividade foram limitadores do aumento das exportaÃÃes, apesar de suas contribuiÃÃes positivas em alguns sub-perÃodos. Os resultados dos indicadores de competitividade analisados indicam que mesmo havendo aumento das exportaÃÃes brasileiras de ACC, o Brasil vem perdendo competitividade externa, dada a lenta evoluÃÃo de suas exportaÃÃes frente aos seus principais concorrentes.
144

O Efeito da modificaÃÃo de ligante asfÃltico com o lÃquido da castanha de caju (LCC) na resistÃncia ao dano por umidade em misturas asfÃlticas / Evaluation of moisture damage in hot mixture asphalt (HMA) containing cashew nut shell liquid (CNSL) modified asphalt binder

Edeilto de Almeida Ribeiro 04 July 2011 (has links)
O dano por umidade à um defeito frequente e um dos principais responsÃveis pelo desgaste prematuro de pavimentos. Esta pesquisa apresenta uma avaliaÃÃo do potencial do LCC como modificador de ligante asfÃltico com relaÃÃo à resistÃncia ao dano por umidadeem misturas asfÃlticas.Propriedades fÃsico-quÃmicas do LÃquido da Castanha de Caju (LCC) mostram-se potencialmente Ãteis para conferir ao Cimento AsfÃltico de PetrÃleo (CAP) maior adesÃo com os agregados.Utilizou-se um CAP convencional classificado por penetraÃÃo como 50/70 e um CAP modificado com 2% de LCC caracterizados quÃmica e reologicamente. Os agregados foram caracterizados atravÃs da fluorescÃncia de Raio-X e com relaÃÃo à forma. Foram dosadas, segundo o mÃtodo Superpave, diferentes misturas asfÃlticas contendo como ligante: CAP, CAP modificado com LCC e CAP e cal como fÃler. A caracterizaÃÃo mecÃnica das misturas foi realizada atravÃs dos ensaios Lottman modificado, MÃdulo de ResiliÃncia (MR) e desgaste CÃntabro. Utilizou-se o Processamento Digital de Imagens (PDI) para verificar o deslocamento da pelÃcula de CAP. Constatou-se que o LCC diminuiu a viscosidade e reduziu as Temperaturas de Usinagem e CompactaÃÃo (TUC) do CAP. Ambas as amostras, CAP e CAP modificado com 2% de LCC, foram classificadas como PG 70-28. Os agregados foram classificados como granÃticos, sub-arredondados, com baixa esfericidade e de textura lisa. Os resultados mostraram que a mistura com CAP modificado com LCC apresentou menor percentual de descolamento da pelÃcula de CAP e desempenho mecÃnico satisfatÃrio se comparada Ãs outras misturas analisadas. Espera-se que o LCC possa ser utilizado como aditivo gerando misturas asfÃlticas menos suscetÃveis à aÃÃo deletÃria da Ãgua. / Moisture damage is a frequent distress on pavements and is considered a major contributor to premature deterioration. Physicochemical properties of the Cashew Nut Shell Liquid (CNSL) showed to be potentially useful to improve the adhesion between asphalt binder and aggregates.The main objective of this study is to evaluate the potential of the CNSL modified asphalt binder to increase the hot mixture asphalt (HMA) resistance to moisture damage, and as a promoter of adhesiveness between binder and aggregates.Pure and modified asphalt binders with different CNSL contents were characterized chemically and rheologically. The aggregates were characterized by X-ray fluorescence and using Aggregate Imaging Measurement System (AIMS). HMAs with binders modified with CNSL were designed using the Superpave methodology. HMA mechanical characterization consisted of modified Lottman test, Resilient Modulus and Cantabro. Results were compared with those obtained using two different HMAs: (i) one with conventional asphalt binder and natural aggregates, and (ii) another one using 2% of lime as a filer. The stripping resistance of asphalt binderswere characterizedthrough digital image processing (DIP). The findings showed the CNSL decreased the asphalt binder viscosity. Both, the pure and the modified asphalt binder, were classified as PG 70-28. The granitic aggregates were classified as sub rounded, with low sphericity and smooth texture. The findings showed that the HMA contain binder modified with CNSL had better stripping resistance and behavior mechanical performance than other evaluated HMAs. Itâs expected that the effectiveness of the CNSL can be used as an additive to prevent striping in asphalt mixtures and to provide a greater resistance to breakdown caused by water.
145

Suco de caju contendo oligossacarÃdeos prÃbioticos / Cashew juice containing prebiotic oligosaccharides

Isabel Moreira da Silva 29 June 2010 (has links)
Os alimentos funcionais constituem hoje prioridade em pesquisas devido a crescente busca dos consumidores por alimentos que alÃm da funÃÃo bÃsica de nutrir possam trazer outros benefÃcios. Dessa forma, estudos para o desenvolvimento de prebiÃticos tornam-se interessantes. A enzima dextrana-sacarase quando em meio contendo sacarose e um aceptor como substrato produz oligossacarÃdeos prebiÃticos. O suco de caju funciona como fonte de aceptores, uma vez que à rico em glicose e frutose. A produÃÃo da enzima dextrana-sacarase pode ser realizada via processo fermentativo atravÃs da inoculaÃÃo da bactÃria Leuconostoc mesenteroides NRRL B512F ao meio de cultura contendo sacarose. Dessa forma o objetivo desse trabalho foi a produÃÃo de oligossacarÃdeos prebiÃticos via processo enzimÃtico com adiÃÃo da enzima dextranaâsacarase ao suco de caju clarificado. Com base nos resultados obtidos, pode-se concluir que o suco de caju clarificado pode ser empregado como uma alternativa de substrato de baixo custo para a sÃntese de oligossacarÃdeos prebiÃticos, por via enzimÃtica utilizando a enzima dextrana-sacarase. O rendimento em dextrana foi favorecido pela combinaÃÃo de baixas concentraÃÃes de sacarose e aÃÃcares redutores. A formaÃÃo de oligossacarÃdeos foi favorecida pelo aumento da concentraÃÃo dos aÃÃcares redutores e pela combinaÃÃo de elevadas concentraÃÃes de sacarose e aÃÃcares redutores. Neste trabalho a maior concentraÃÃo de oligossacarÃdeos obtida foi de 104,73 g/L utilizando-se 75 g/L de sacarose em combinaÃÃo com 75 g/L de aÃucares redutores e por fim a anÃlise qualitativa mostrou que em concentraÃÃes de 25 g/l e 75 g/l de sacarose e aÃÃcar redutor, respectivamente foi possÃvel obter oligossacarÃdeos de grau de polimerizaÃÃo atà 12. / Functional foods are now a research priority due to growing demand for foods that, besides the basic function of nurture, can bring benefits. Thus, studies for the development of prebiotics become interesting. The enzyme dextransucrase in a medium containing sucrose and an acceptor as substract synthesizes prebiotics oligosaccharides. The cashew apple juice works as a source of acceptors, since it is rich in glucose and fructose. The production of dextransucrase enzyme can be accomplished by fermentative process by inoculating the bacterium Leuconostoc mesenteroides NRRL B512F into a culture medium containing sucrose.Thus the aim of this work was the production of prebiotic oligosaccharides by enzymatic process with addition of the dextransucrase enzyme to the clarified cashew apple juice. Based on the results we can conclude that the clarified cashew apple juice can be used as low cost alternative substrate for the synthesis of prebiotic oligosaccharides through enzyme synthesis using the dextransucrase enzyme. Dextran yeld was favored by the combination of low concentrations of sucrose and reducing sugars. The formation of oligosaccharides was favored by increasing the concentration of reducing sugars and by the combination of high concentrations of sucrose and reducing sugars, where the largest concentration of oligosaccharides obtained was 104.73 g/L using 75g/L sucrose in combination with 75g/L of reducing sugars and finally the qualitative analysis shows that at concentrations of 25 g/L and 75g/L sucrose and reducing sugar, respectively, is possible to obtain oligosaccharides of degree of polymerization up to 12.
146

Diversidade cultural, morfolÃgica e patogÃnica de isolados de Lasiodiplodia theobromae associados a frutÃferas tropicais / Cultural, morphological and pathogenic isolates Lasiodiplodia theobromae associated with tropical fruit

Joilson Silva Lima 29 July 2011 (has links)
CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Lasiodiplodia theobromae à um fungo cosmopolita, polÃfago e oportunista, com reduzida especializaÃÃo patogÃnica, que infecta espÃcies de plantas em regiÃes tropicais e temperadas, causando os mais variados sintomas. A crescente expansÃo das doenÃas causadas por L. theobromae em frutÃferas tropicais vem causando inestimÃveis perdas, tanto no sistema produtivo como em pÃs-colheita, representando uma ameaÃa à fruticultura no Nordeste. Daà a necessidade de conhecimentos bÃsicos sobre a biologia populacional e a interaÃÃo do patÃgeno com as plantas hospedeiras. Este estudo teve como objetivo caracterizar isolados de L. theobromae associados a frutÃferas tropicais de diferentes regiÃes, avaliando o aspecto cultural, morfolÃgico e patogÃnico. Foram avaliados o crescimento micelial, coloraÃÃo da colÃnia, dimensÃes dos conÃdios e patogenicidade dos isolados em mudas de cajazeira, cajueiro, gravioleira e umbuzeiro. O trabalho foi realizado na Casa de VegetaÃÃo e no LaboratÃrio de Fitopatologia da Embrapa AgroindÃstria Tropical. Os dados de caracterizaÃÃo morfocultural mostraram haver alta diversidade na populaÃÃo do patÃgeno. As inoculaÃÃes realizadas nas quatro diferentes espÃcies hospedeiras apontaram alta variabilidade patogÃnica entre os isolados do fungo. Em mudas de cajueiro CCP 76 nÃo foi possÃvel observar especificidade patogÃnica, pois todos os isolados apresentaram similar nÃvel de agressividade, demonstrando a suscetibilidade deste clone ao patÃgeno, suscetibilidade essa, tambÃm observada em gravioleira. O umbuzeiro foi a espÃcie que apresentou maior resistÃncia ao fungo. Os dados mostraram que existe interaÃÃo entre as caracterÃsticas morfoculturais e a agressividade dos isolados de L. theobromae. De acordo com os resultados, a altitude dos locais de origem dos isolados nÃo influencia em suas caracterÃsticas morfoculturais e patogÃnicas. / Lasiodiplodia theobromae is an ubiquitous, polyphagous and opportunistic fungus with a reduced pathogenic ability. Nevertheless, it may infect several plant species over tropical and temperate regions, causing many different kinds of symptoms. The increasingly expansion of diseases caused by L. theobromae in tropical fruit plants has been imposing severe losses both at orchard level and in post-harvest at market, threaten the fruit crop industry in Northeast Region of Brazil. Therefore there is an urgent need for research pursuing basic knowledge on population biology of the fungus and host-pathogen interactions. This study aimed to characterize a L. theobromae population which has been associated to tropical plant species growing under different ecosystems in northeastern Brazil. Colony growth in culture, color and size of conidia and ability to cause disease upon inoculation on cashew nut (Anacardium occidentale), soursop (Annona muricata), yellow mombin (Spondias mombin) and Brazil plum (Spondias tuberosa) were evaluated. He study was carried out at Plant Pathology Lab and screenhouse of Embrapa Agroindustria Tropical in Fortaleza, Cearà State. Results showed a high diversity of morphology and hyphal growth among fungus isolates. Also, a very high variability on disease expression upon inoculation into four plant species was observed. However, it was found a lack of specificity of isolates as to infect cashew plants, since all isolates were able to infect cashew with similar high aggressiveness, which demonstrated a high degree of susceptibility of cashew clone used (CCP 76). Similar results were found also for soursop plants as host. Brazil plum showed a very high resistance to all isolates. The data points out for the existence of morphological and pathogenic interactions within L. theobromae population studied. According with the results, altitude and region of isolate origin has no effect on the studied features.
147

Environmentally acceptable friction composites

Newby, William Robert January 2014 (has links)
Currently, the production of most non-asbestos organic (NAO) friction materials depends on a long and energy intensive manufacturing process and an unsustainable supply of synthetic resins and fibres; it is both expensive and bad for the environment. In this research, a new, more energy efficient, manufacturing process was developed which makes use of a naturally derived resin and natural plant fibres. The new process is known as 'cold moulding' and is fundamentally different from the conventional method. It was used to develop a new brake pad for use in low temperature (<400 °C) applications, such as rapid urban rail transit (RURT) trains. A commercially available resin based upon cashew nut shell liquid (CNSL) was analysed and found to have properties suitable for cold moulding. In addition, hemp fibre was identified as a suitable composite reinforcement. This was processed to improve its morphology and blended with aramid to improve its thermal stability. Each stage of cold mould manufacture was thoroughly investigated and the critical process parameters were identified. The entire procedure was successfully scaled up to produce an industrially sized 250 kg batch of material and the resultant composites were found to have appropriate thermal and mechanical properties for use in a rail brake pad. The tribological performance of these composites was iteratively developed through a rigorous testing and evaluation procedure. This was performed on both sub- and full-scale dynamometers. By adding various abrasives, lubricants, and fillers to the formulation it was possible to produce a brake pad with similar friction characteristics to the current market material, but with a 60% lower wear rate. In addition, this brake pad caused 15% less wear to the brake disc. A detailed examination of both halves of the friction couple found that cold moulded composites exhibit a different wear mechanism from the current market material, which was suggested to be the reason for their superior properties. Cold moulding is 3.5x faster and uses 400% less energy than the conventional method.
148

Preparo, caracterização e avaliação funcional de microcapsulas obtidas por spray drying, contendo extrato de cafe crioconcentrado / Preparation, charaction and funcional evaluation of microcapsules obtained by spray drying, containing cryoconcentrated coffee extract

Rodrigues, Rodney Alexandre Ferreira, 1964- 14 December 2004 (has links)
Orientador: Carlos Raimundo Ferreira Grosso / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T01:22:27Z (GMT). No. of bitstreams: 1 Rodrigues_RodneyAlexandreFerreira_D.pdf: 5653563 bytes, checksum: 3722a3f854c6082410b047a12b90764c (MD5) Previous issue date: 2004 / Resumo: A microencapsulação em spray dryer tem sido amplamente empregada na indústria alimentícia, visando a proteção do recheio. Atualmente, a goma arábica e a maltodextrina são utilizadas como material de parede e a goma do cajueiro ainda não foi estudada para esta finalidade. Com isso, o objetivo deste trabalho, foi avaliar a retenção de voláteis, após a microencapsulação de extrato de café pela técnica de spray drying, utilizando-se maltodextrina, goma arábica e goma do cajueiro como agentes microencapsulantes. As microcápsulas obtidas foram caracterizadas por Karl Fischer, proteína, atividade de água e distribuição do tamanho de partículas. Além disso, foi avaliada a estabilidade física e química por microscopia eletrônica de varredura e Cromatografia Gasosa-Espectrometria de Massas (CG-EM). A extração assistida por microondas foi empregada para a extração do recheio, devido a sua simplicidade operacional, rapidez e por permitir a extração de várias amostras ao mesmo tempo. A identidade dos compostos contidos no recheio, foi sugerida por comparação dos espectros de massas com os da biblioteca NIST. O perfil cromatográfico obtido por CG-EM para as diferentes amostras de microcápsulas demonstrou uma similaridade na avaliação qualitativa. A análise sensorial foi realizada com 39 provadores, utilizando-se as microcápsulas em estudo, comparadas a um padrão de café instantâneo em pó, obtido em spray dryer. Foi observado que não houve diferença significativa entre as microcápsulas testadas e o padrão / Abstract: Microencapsulation using spray dryer has been widely used in food industry, seeking core protection. Nowadays, the gum arabic and maltodextrin have been used as wall material, but cashew gum was still not studied as a microcapsule for this purpose. This way, the objective of this work was studied the volatile retention of coffee extract during microencapsulation by a spray drying technique using maltodextrin, gum arabic and cashew gum as microencapsulating agents. The microcapsules obtained were characterizated by Karl Fischer, protein, water activity, particle size distribution. Besides, the physical and chemical stability were studied by scanning electron microscopy and Gas Chromatography-Mass Spectroscopy (GC-MS). Microwave assisted extraction was used for core extrraction, who allows operacional simplicity, rapid extraction and multiple extraction at same time. The identities of the compounds in the core were suggested by comparison of their mass spectra with those of the NIST¿s library spectra. The chromatographic profile of microcapsules samples obtained by GC-MS was similar in the qualitative evaluation. A sensory analysis was carried out with 39 consumers, comparing the studied microcapsules with instantaneous coffee powder standard obtained by spray drying. It was observed that there was not a significant difference between the microcapsules and the standard / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos
149

Estudos relativos a biodiesel : (i) determinação de metóxido de sódio por termometria, (ii) estudo da influência do líquido da castanha de caju na estabilidade oxidativa de diferentes tipos de biodiesel / Studies on biodiesel : (i) determination of sodium methoxide for thermometry, (ii) study of the influence of liquid net cashew on oxidative stability of different types of biodiesel

Bastos, Flavio Adriano, 1976- 26 August 2018 (has links)
Orientador: Matthieu Tubino / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T17:54:49Z (GMT). No. of bitstreams: 1 Bastos_FlavioAdriano_D.pdf: 1277928 bytes, checksum: 9039000b025b809b99909b347545f47f (MD5) Previous issue date: 2014 / Resumo: A primeira parte deste trabalho consiste na apresentação de um novo método, seletivo e quantitativo, para a determinação de metóxido de sódio em solução metanólica, utilizando-se a termometria. O metóxido é usado como reagente em muitos processos industriais, como na indústria farmacêutica e também como catalisador na síntese de biodiesel. O método desenvolvido está baseado no aumento da temperatura da solução como consequência da reação exotérmica entre a água e o íon metóxido. Em relação ao método atualmente usado, ele apresenta vantagens como maior rapidez e simplicidade nas análises, além de custo mais baixo. Os resultados obtidos pelos dois métodos foram submetidos a testes estatísticos que comprovaram, em nível de confiança de 95%, que os resultados obtidos com os dois procedimentos não diferem entre si. Os valores de desvio padrão estão abaixo de 2,0 %. O método proposto pode ser aplicado, por exemplo, no controle da concentração de metilato de sódio em lotes do produto adquirido para fins de síntese e, também, no controle da produção industrial deste reagente. Na segunda etapa, foi realizado o estudo da influência do líquido obtido da casca de castanha de caju (LCC) na estabilidade oxidativa de biodieseis oriundos de óleos de soja, de milho, de canola e de girassol utilizando-se o método Rancimat® e variando-se a concentração do antioxidante para cada um dos tipos de biodiesel. Em todos os casos, pode-se observar que a adição do antioxidante eleva a resistência à oxidação do biodiesel, sendo que concentrações, em mol L-1, da ordem de 10-5, para o biodiesel de girassol, e de 10-3 para os demais, já se nota ação antioxidante em função da diminuição da velocidade de oxidação do biodiesel estudado. Também foram determinados parâmetros cinéticos e termodinâmicos das reações envolvendo o antioxidante / Abstract: The first part of this work presents a new and selective quantitative analytical thermometric method for sodium methoxide determination in methanol solutions in the presence of hydroxide ions. The sodium methoxide is used as a reagent or a catalyst in many industrial processes such as, for example, pharmaceuticals and biodiesel syntheses. The procedure is based on the measurement of the temperature increase of the solution caused by the exothermic reaction between water and the ion methoxide. In relation to the current method, the method proposed has advantages such as lower cost and has greater speed and simplicity analysis, besides is faster. The results obtained in this work were compared with those obtained by current method were subjected to statistical tests proved that, within certain levels of confidence, the results obtained by the proposed method does not differ significantly from the current method used by manufacturers. The observed relative standard deviations are below 2,0 %. The proposed method can be applied, for example, in incoming inspection of raw materials and in quality control of the industrial production of sodium methoxide. In the second part of this work we carried out a study of cashew nut shell liquid (CNSL) influence as antioxidant on biodiesel came from the refined vegetable oils from soybean, sunflower, canola and corn through the official Rancimat® method. The tests were performed varying the temperature and concentration of the antioxidant for each of the biodiesel. In all cases, it can be seen that the addition of antioxidant increases the oxidation resistance of biodiesel, with concentrations, in mol L-1, in the order of 10-5 for sunflower biodiesel and 10-3 for the other ones, already observed antioxidant activity due to the decrease in the rate of oxidation of biodiesel studied. Besides that, it was determined kinetics and thermodynamics parameters from the antioxidant action / Doutorado / Quimica Analitica / Doutor em Ciências
150

Organisational Learning in Business Model Innovation in the Bottom of Pyramid market : An empirical fieldwork about the market introduction of clean cookstoves in Mozambique

Premer, Stefan, Nansubuga, Brenda January 2018 (has links)
There is a need for cleaner technology initiatives into the Bottom of the Pyramid (BoP) market to combat the effects of climate change. The difficulty of these initiatives lies in their business model innovation process, as those organisations struggle in finding adequate strategies to establish their business in the BoP market. The BoP market is characterised as highly uncertain, which makes the operation of businesses challenging. Hereby the thesis aims at answering the question on how organisational learning occurs in business model innovation in the BoP market. Through a case study approach, the thesis intends to understand the requirements to establish a functioning business model by analysing organisational learning under business model innovation within the BoP market. This has been realised through a three week field study in Northern Mozambique, observing the market introduction of a cleantech company operating in this context. Hereby the business model innovation process and the environment of operation was analysed. This research contributes to the current discussion of business model innovation in BoP markets by detecting organisational learning as a useful mechanism and adding relevant insights on how organisational learning occurs in this specific context. Therefore the study opens the discussion on organisational learning in business model innovation in the context of the BoP market by asking for further studies on the topic.

Page generated in 0.0318 seconds