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  • 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.
671

Purification and characterisation of novel recombinant β-glucosidases from aspergillus with application in biofuel production

Auta, Richard January 2015 (has links)
β-glucosidases are important components of the cellulase enzyme system in which they not only hydrolyse cellobiose to glucose, but also remove the feedback inhibition effects of cellobiose on exoglucanase and endoglucanase thereby increasing the rate of cellulose degradation to fermentable sugars. A total of 166 proteins were identified as β-glucosidases after manual BLASTp search on the Aspergillus comparative database from eight species. Evidence for Horizontal Gene Transfer (HGT) of bacterial origin of some β-glucosidase genes was provided by their lack of introns, absence of some fungal specific amino acid insertions in their sequences and unusual positions in phylogenetic trees showing similarities to bacterial proteins. A rapid plate assay based on Congo red methods was developed to study the optimum parameters such as pH and temperature for growth of strains and activities of the enzymes produced. Bacterial cellulose (BC) was produced by Gluconacetobacter xylinus. For the first time a fully detailed characterization by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Differential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and 13Carbon Solid State Nuclear Magnetic Resonance (SSNMR) of pure BC before and after treatment with a commercially available Aspergillus cellulase enzyme was demonstrated. Two encoding sequences for novel Aspergillus nidulans hydrophobin genes ANID_05290.1 and ANID_07327 that do not fall into either the class I or class II category of hydrophobins were successfully cloned. Two encoding sequences for a novel β-glucosidase gene from an Aspergillus niger strain from Nigeria were amplified and cloned from genomic DNA using PCR. Aspergillus nidulans β-glucosidases (AN2227 and AN1804) expressed in Pichia were purified to homogeneity by using ammonium sulphate precipitation and DEAE-Sephadex A-50 chromatography. Both enzymes had a remarkably broad pH and temperature profile. Further experiments on the development of a technology for lignocellulose degradation based on co-production of β-glucosidase with hydrophobin for biofuel production are suggested.
672

Optical emission spectroscopy of laser induced plasmas containing carbon and transitional metals

Motaung, David Edmond January 2008 (has links)
Magister Scientiae - MSc / The spectroscopic, SEM and Raman measurements on carbon nanotubes under the exact conditions of which OES analysis were made showed that at a pressure of 400 Torr and a flow rate of 200 sccm, the quality and quantity of single-walled carbon nanotubes was the highest. / South Africa
673

A systematic appraisal of the Eriophyoidea (Acari Prostigmata)

Craemer, Charnie 18 October 2011 (has links)
The diversity of the Eriophyoidea is largely unknown and their systematic study mostly entails alpha-taxonomy which is critically important for these mites. Eriophyoid morphology is almost exclusively studied on slide-mounted specimens, and truly permanent specimen slides cannot be prepared and are eventually lost. Shortcomings in taxon descriptions are persistent, and too few morphological characters are available for systematic use, particularly for phylogenetic studies. The fragile, simplified and minute eriophyoid bodies, and the inadequacy of study methods and technology, including preparation and light microscopy, contribute to these problems. The present eriophyoid classification is widely accepted, relatively stable and useful. The major part of the classification, however, is probably artificial, and some taxon delimitations and identifications are becoming increasingly difficult. Scanning electron microscopy (SEM) is only sporadically used to supplement conventional descriptions of eriophyoid mites, and their phylogeny has hardly been studied. In the present study some aspects of eriophyoid systematics and its improvements by incorporating SEM for morphological study and phylogenetic analyses for testing and improving the naturalness of the present eriophyoid classification, are used and appraised. The morphology of about 64 species, mostly from South Africa, was studied with low-temperature (cryo) SEM. The specimens remained turgid and the shape of the mites largely unaltered. A general overview of the contribution of the SEM study towards systematic morphology of the Eriophyoidea is presented. Discrepancies between species descriptions from slide-mounted specimens and the SEM images were found. These include body form, interpretation of structures, resolution and information on minute morphology, and the presence of secretions. Some of these differences were caused by artefacts introduced with slide-mounting of specimens. The SEM study includes a comparative morphological study of the gnathosoma, including a review and appraisal of characters presently used in eriophyoid systematics. New morphological information was found, including new characters that may be of systematic use. Morphology studied with SEM should be routinely incorporated into eriophyoid descriptions, which is not presently the case. The phylogeny of the Eriophyoidea was studied at genus level, using morphological data, to test the monophyly of the present suprageneric taxa. Three data matrices with 66, 60 and 27 informative characters of 316 (including most Diptilomiopus spp.), 64 and 17 eriophyoid ingroup species respectively were analyzed with parsimony analyses, and trees were searched under different parameters. This was done to find different hypotheses regarding the taxon relationships, to roughly assess the robustness of the tree groups, and to use different approaches: a very comprehensive taxon sample, but with low ratio of characters to taxa; an exemplar species sample to improve the ratio between characters to taxa; and a very small taxon sample with a good ratio between characters and taxa, but very little inclusion of variation found in the Eriophyoidea. Most groups found were supported only by homoplasy, but many made biological sense and various potentially monophyletic groups, additional to taxa in the present classification, are proposed for further study. The robustness and convergence of these groups on monophyly are discussed. The Phytoptidae was found to be polyphyletic. Part of the Nalepellinae is probably positioned outside the remainder of the Eriophyoidea, while the rest of the Phytoptidae were positioned in smaller subgroups among the Eriophyidae. The Phytoptinae and Sierraphytoptinae, including Pentasetacus, may group together. The Eriophyidae never grouped together with much support, and the family is both polyphyletic and paraphyletic. The Diptilomiopidae was largely found to be monophyletic, with a relatively strong phylogenetic structure. The Rhyncaphytoptinae is mainly paraphyletic, and the Diptilomiopinae polyphyletic, but part of the Diptilomiopinae may be monophyletic. Three new Diptilomiopus spp. from South Africa are described as part of the study: D. faurius sp. nov. from Faurea rochetiana (A. Rich.) Pic. Serm. (Proteaceae); D. apobrevus sp. nov. and D. apolongus sp. nov. from Apodytes dimidiata E. Mey. ex Arn. (Icacinaceae). They were leaf vagrants not causing any observable symptoms. / Thesis (PhD)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted
674

Estudo do efeito do "stress" alcalino na produção de goma xantana / Study of the effect of alkaline "stress" in production xanthan gum

Luvielmo, Marcia de Mello 08 August 2018 (has links)
Orientador: Adilma Regina Pippa Scamparini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T02:50:35Z (GMT). No. of bitstreams: 1 Luvielmo_MarciadeMello_D.pdf: 3297730 bytes, checksum: dc80c8868bb6f8fa43b93b87d5e0bae3 (MD5) Previous issue date: 2007 / Resumo: O presente estudo teve como objetivo fazer uma seleção de linhagens de X. campestris para a produção de goma xantana e verificar o efeito do processo de ¿stress¿ alcalino em diferentes condições de produção deste biopolímero, através da avaliação da produção de goma e da viscosidade aparente, que é um fator de elevada relevância para designar em quais processos e setores da indústria a goma xantana será aplicada. A pesquisa também teve como objetivo investigar as mudanças na estrutura da goma xantana causadas pelo ¿stress¿ alcalino, e as mudanças na ultraestrutura das células, assim como a disposição da goma em diferentes etapas da sua produção e em diferentes tempos de ¿stress¿ alcalino, a fim de contribuir com uma maior compreensão desse complexo processo. Foi selecionada a linhagem X. campestris pv. manihotis 280-95, como a de melhor desempenho em produção e qualidade, com uma produção de goma xantana de 10,8 g/L. A partir destes estudos, X. campestris pv. manihotis 280-95 passou a ser a bactéria utilizada para os estudos posteriores. O maior valor de produção de goma xantana foi atingido em ¿stress¿ alcalino com pH 12 (EA12), seguido do ¿stress¿ alcalino em pH 11 (EA11) e ¿stress¿ alcalino em pH 8 (EA08). Porém a qualidade da goma obtida após o processo de EA12 é menor se comparada à obtida sem o processo de ¿stress¿ alcalino. O hidróxido de sódio (NaOH) foi o álcali que apresentou melhor desempenho para o processo de ¿stress¿ alcalino. A produção de goma xantana (g.L-1) e as viscosidades aparentes das gomas não foram afetadas nos diferentes tempos de ¿stress¿ alcalino (EA12) testados nesse estudo (1h, 2h, 3h e 4h), na faixa de taxa de deformação testada (0 ¿ 60 s-1). A produção de goma xantana obtida da fermentação realizada em bioreator de 2 L utilizando X. campestris pv. manihotis 280-95 foi maior após o processo de ¿stress¿ alcalino por 24 horas (EA24h). Ao final de 72 horas de fermentação 9,43 g.L-1 de goma xantana foram obtidos e após 24 horas de ¿stress¿ alcalino, a produção foi 74,8% maior (16,48 g.L-1). No estudo das ultraestruturas (capítulo IV) foi possível visualizar cada passo dos processos e verificar que, mesmo no inóculo puro, observa-se também uma pequena produção de goma xantana próximo a algumas células. No final da fermentação (FF), observou-se o início de mudanças estruturais nas bactérias, como a vacuolização citoplasmática e a descontinuidade da membrana, podendo sugerir um início no processo de lise bacteriana. Após o ¿stress¿ alcalino (EA12-1h), foram observadas acentuadas diferenças estruturais nas células bacterianas. O conteúdo citoplasmático das bactérias tornou-se mais vacuolizado e verificou-se descontinuidade nas membranas das células bacterianas, indicando processo de lise bacteriana. A goma xantana que se apresentou agrupada em grumos, adquiriu uma conformação organizada em círculos concêntricos. Finalmente, pode ser mencionado que novos estudos com diferentes linhagens e condições de processo devem ser realizados procurando-se sempre melhores resultados de produção e qualidade desse biopolímero / Abstract: The present study had as objective to make a selection of strains of X. campestris for the production of xanthan gum and to verify the effect of the process of alkaline "stress" at different conditions of production of this biopolymer, through the evaluation of the gum production and of the apparent viscosity, which is a factor of high relevance, in order to allocate which processes and sections of the industry the xanthan gum will be applied in. The research also aimed to investigate changes in the structure of the xanthan gum caused by the alkaline "stress", changes in the ultrastructure of the cells, as well as the disposition of the gum at different stages of its production and at different times of alkaline "stress", so as to contribute with a better understanding of such compound process. The strain was selected X. campestris pv. manihotis 280-95, as better acting in production and quality, with a production of xanthan gum of 10,8 g.L-1 starting from these studies, X. campestris pv. manihotis 280-95 started to be the bacterium used for the subsequent studies. The largest value of production of gum xantana was reached in alkaline "stress" with pH 12 (EA12), followiedby the alkaline "stress" in pH 11 (EA11) and alkaline "stress" in pH 8 (EA08). However, the quality of the gum obtained after the process of EA12 is worse compared to what was obtained without the process of alkaline "stress." The hydroxide of sodium (NaOH) was the alkali that presented better results in obtaining the process of alkaline "stress." The production of xanthan gum (g.L-1) and the apparent viscosities of the gums were not affected in the different times of alkaline "stress" (EA12) tested in that study (1:00, 2:00, 3:00 and 4:00), at the shear rate range tested (0 - 60 s-1). The production of xanthan gum obtained from the fermentation accomplished in bioreactor of 2 L using X. campestris pv. manihotis 280-95 was larger after the process of alkaline "stress" within 24 hours (EA24h). At the end of 72 hours of fermentation 9,43 g.L-1 of xanthan gum were obtained and after 24 hours of alkaline "stress", the production was 74,8% larger (16,48 g.L-1). In the study of the ultrastructures (chapter IV) it was possible to observe each step of the processes and to verify that, even in the pure inoculum, it is also observed a small production of gum close to some cells. Atthe end of the fermentation (FF), the beginning of structural changes was observed in the bacteria, as the vacuum cytoplasm and the discontinuity of the membrane, could suggest a beginning in the process of bacterial lise. After the alkaline "stress" (EA12-1h), accentuated structural differences were observed in the bacterial cells. The content cytoplasm of the bacteria became more vacuuming and discontinuity was verified in the membranes of the bacterial cells, indicating process of bacterial lysis. The resulting xanthan gum presented in clots, acquired an organized conformationin concentric circles. Finally, it can be mentioned that new studies with different strains and process conditions should be accomplished being always sought better production results and quality of that biopolymer / Doutorado / Doutor em Ciência de Alimentos
675

Sistemas adesivos universais = resistência de união ao esmalte e dentina, padrão de fratura e análise ultramorfológica = Universal adhesive systems: bond strength to enamel and dentin, failure pattern and ultramorphology analysis / Universal adhesive systems : bond strength to enamel and dentin, failure pattern and ultramorphology analysis

Vermelho, Paulo Moreira, 1967- 27 August 2018 (has links)
Orientador: Marcelo Giannini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-27T18:34:59Z (GMT). No. of bitstreams: 1 Vermelho_PauloMoreira_D.pdf: 2479320 bytes, checksum: 0d9cc50e5276a8b6e9a933c7dcd3239c (MD5) Previous issue date: 2015 / Resumo: Os objetivos deste estudo foram analisar as características ultramorfológicas da interface de união dente-resina, a resistência de união ao esmalte e dentina pelo método da microtração e os padrões de fratura dos espécimes testados. Dois adesivos "universais ou multi-molde" (Scotchbond Universal, 3M ESPE e All-Bond Universal, Bisco) foram testados nos modos autocondicionantes e com condicionamento prévio e comparados aos métodos tradicionais de união ao esmalte e dentina (grupos controles) utilizando os adesivos Optibond FL (Kerr) e Clearfil SE Bond (Kuraray Noritake). Esmalte e dentina de terceiros molares humanos foram utilizados nos procedimentos adesivos, os quais foram realizados com as instruções dos fabricantes. Após a aplicação dos adesivos, um bloco de compósito foi construído em incrementos. Os dentes foram seccionados longitudinalmente para obtenção de espécimes em formato de "palitos" para o ensaio de resistência de união por microtração (n=8) e as análises em microscopia eletrônica de transmissão (MET) (n=2). Os espécimes foram testados após 24 horas ou um ano de armazenamento em saliva artificial. Para a MET, solução traçadora de nitrato de prata foi utilizada para mostrar espaços nanométricos e evidências de degradação na área de união. As superfícies fraturadas dos espécimes foram observadas em microscopia eletrônica de varredura e os dados de resistência de união analisadas pela ANOVA três-fatores, teste de Tukey e Dunnett (5%). O condicionamento prévio do esmalte aumentou a resistência de união dos adesivos universais, mas essa reduziu após o armazenamento por um ano. Os adesivos universais mostraram menor resistência de união em esmalte que o grupo controle quando utilizados no modo autocondicionante no tempo de 24 horas. Nenhuma diferença significativa foi encontrada na resistência de união em dentina nos dois tempos de avaliação quando comparados aos adesivos universais e os controle. O armazenamento por um ano reduziu a resistência de união em dentina apenas para um adesivo universal usando no modo autocondicionante. A análise fractográfica em esmalte mostrou predomínio de fraturas mistas e coesivas na camada de adesivo. Em dentina, o predomínio foram fraturas mistas, adesivas e coesivas em compósito. A observação da ultramorfologia em MET mostrou a formação de hibridização e zonas de interação entre todos os adesivos em esmalte e dentina nos dois modos de aplicação. Sinais de nanoinfiltração foram identificados na área de união dentina-resina para os adesivos Scotchbond Universal e Clearfil SE Bond após armazenamento por um ano. Os resultados sugerem que armazenamento por um ano pode reduzir a resistência de união quando os adesivos universais foram aplicados em esmalte condicionado, mas em dentina condicionada não houve redução da resistência de união, exceto para o adesivo Scotchbond Universal. No esmalte a resistência de união do grupo controle foi maior que a dos adesivos universais no modo autocondicionante. Após o armazenamento por um ano, a resistência de união dos adesivos universais em esmalte tratado com ácido fosfórico não diferiu do grupo controle. Em dentina, não foi encontrada diferença significativa entre adesivos universais e os grupos controles, independente do modo de condicionamento / Abstract: The aims of this study were to analyze the ultramorphological characteristics of tooth¿resin interfaces, the microtensile bond strength of multimode adhesive systems bonded to enamel and dentin, and the failure pattern of tested specimens. Two multimode adhesives (Scotchbond Universal, 3M ESPE; All-Bond Universal, Bisco) were tested in both self-etch and etch-and-rinse modes and compared to control groups using traditional bonding techniques (Optibond FL, Kerr; Clearfil SE Bond, Kuraray Noritake) in enamel and dentin. Enamel and dentin from third human molars were used for bonding and adhesives used according to the manufacturer¿ instructions. A composite resin block was incrementally applied to bonded surfaces, and teeth were sectioned transversely to the tooth-composite interface to obtain specimens for microtensile bond strength (n=8) and transmission electron microscopy (TEM) analysis (n=2). Specimens were tested after storage for either 24 hours or 1 year in artificial saliva. For TEM, a silver tracer solution was used to reveal nanometer-sized spaces and evidence of degradation within resin¿dentin interfaces. Fractured surfaces of tested specimens were analyzed under scanning electron microscopy. Bond strength data were analyzed by three-way ANOVA and by Tukey¿s and Dunnett¿s tests (?=5%). The acid-etching mode increased the enamel bond strength of multimode adhesives; however, bond strength decreased after storage for 1 year. Multimode adhesives showed lower enamel bond strength than the control group adhesive when used in self-etch mode for 24 hours. No significant differences in dentin bond strength were noted between multimode and control adhesives in either evaluation period. Storage for 1 year only reduced the dentin bond strength for a multimode adhesive used in self-etch mode. Mixed and cohesive-within-adhesive-layer failures were predominant in enamel. In dentin most fractures were mixed, adhesive along the dentin or enamel, and cohesive within the composite layer. TEM analysis identified hybridization and interaction zones in dentin and enamel for all adhesives and application modes. Silver impregnation was detected on dentin¿resin interfaces after storage of specimens for 1 year only with the Scotchbond Universal and Clearfil SE Bond samples. Results suggested that storage for 1 year can reduce bond strength when multimode adhesives are applied on an etched surface, but the dentin bond strength was not affected when using the etch-and-rinse mode (except for the Scotchbond Universal sample). The enamel bond strengths of the control group adhesives were higher than those obtained for multimode adhesives in the self-etch mode. After storage for 1 year, the bond strengths of multimode adhesives in etched enamel did not differ from those of the control group adhesive. In dentin, no significant difference was noted between the multimode and control group adhesives, regardless of etching mode / Doutorado / Dentística / Doutor em Clínica Odontológica
676

Caracterização molecular e morfológica de isolados brasileiros do gênero Euglena. / Molecular and morphological characterization of Brazilian isolates of the genus Euglena.

Adriana Vieira de Castro Martins 12 February 2009 (has links)
Neste estudo foram isolados e caracterizados flagelados de 20 amostras de solo e água do Brasil classificados no gênero Euglena por parâmetros taxonômicos tradicionais, e distribuídos em 5 grupos de acordo com características morfológicas. Análises filogenéticas do gene SSUrDNA das 20 amostras resultou em 25 seqüências posicionadas nos grupos A2 e A3 do gênero Euglena definidos em estudos anteriores, separando as seqüências obtidas em 7 clados distintos, revelando uma maior diversidade que a obtida por parâmetros taxonômicos tradicionais. A fim de resolver os relacionamentos intra-específicos do grupo A3, realizamos uma análise filogenética restrita deste grupo, que apresentou árvores congruentes e subclados bem suportados. Representantes de cada espécie foram analisados por microscopia eletrônica de varredura, revelando dois padrões principais de estrias e poros da película. Os isolados caracterizados neste estudo são os primeiros do Brasil estabelecidos em cultura, validados por análises filogenéticas e morfologicamente caracterizados. / In this study we isolated and characterized flagellates from 20 soil and water samples of Brazil, classified in the genus Euglena based on traditional taxonomic parameters and distributed in 5 groups according to morphological characteristics. Phylogenetic analyses of the SSUrDNA of the 20 samples resulted in 25 sequences that where positioned in previously defined groups A2 and A3 of the genus Euglena, separating the obtained sequences in 7 distinct clades, revealing a larger diversity than defined by traditional taxonomic parameters. To better resolve the intra-specific relationships of group A3, we conducted a phylogenetic analyses restricted to this group, generating congruent trees and well supported sub-clades. A representative of each species was selected and analyzed by scanning electron microscopy, revealing two major patterns of strip and pellicle pores. The isolates characterized in this study are the first in Brazil to be established in culture, validated by phylogenetic analyses and morphologically characterized.
677

Avaliação dos efeitos antineoplásicos do Amblyomin-X em carcinoma de células renais. / Evaluation of Amblyomin-X antineoplasic effects on renal cell carcinoma.

Hamilton de Campos Zampolli 16 September 2011 (has links)
Introdução: O carcinoma de células renais metastático (CCRm) é um tumor altamente agressivo e resistente. Seu tratamento é baseado em terapia alvo molecular e citocinas. Avaliamos os efeitos antineoplásicos do Amblyomin-X, sobre CCR. Métodos: Avaliadas culturas de CCR RENCA e fibroblastos normais NIH/3T3 tratadas ou não com Amblyomin-X. Realizados ensaios de viabilidade celular por MTT e determinação, por citometria de fluxo, da proporção de células em apoptose/necrose; expressão da P-gp; Bad; Bax; Bcl-2; ciclina D1; caspase 3; Ki-67; p53; VEGFR1; citocromo c; análise das fase do ciclo celular; e atividade do proteassoma. Analisamos as populações celulares por microscopia eletrônica de varredura. Empregados testes T e One-way ANOVA para análise estatística. Resultados: O Amblyomin-X demonstrou citotoxicidade em células RENCA por indução de apoptose, diminuição de proliferação celular, inibição do proteassoma e modulação do ciclo celular em G0/G1. Em fibroblastos normais não houve citotoxicidade Conclusão: O Amblyomin-X apresentou efeito antineoplásico em CCR e não exerceu efeito citotóxico em células normais, demonstrando um possível potencial terapêutico no tratamento do CCRm. Estudos futuros deverão confirmar estes resultados. / Introduction: Metastatic renal cell carcinoma (mRCC) is a highly agressive and resistant tumour. Its treatment is based on targeted therapies and cytokines. We have evaluated the antineoplasic effects of Amblyomin-X on RCC. Methods: RCC (RENCA) and fibroblasts (NIH/3T3) cell cultures treated or not with Amblyomin-X were evaluated. MTT assay was performed to determine cell viability. Apoptosis/necrosis ratio; expression of P-gp; Bad; Bax; Bcl-2; cyclin D1; caspase-3; Ki-67; p53; VEGFR1; cytochrome c; cell cycle analysis and proteasome activity were obtained by flow cytometry. Cellular populations were analised by Scanning Electron Microscopy. Statistical analyses was performed using T-Tests and One-way ANOVA. Results: Amblyomin-X showed cytotoxic activity on RENCA tumor cells. It has induced apoptosis, decreased tumor cell proliferation, targeted the ubiquitinproteasome system and modulated genes related to cell cycle in G0/G1. There was no toxicity on fibroblasts. Conclusion: Amblyomin-X showed antineoplasic effects on RCC cells preserved normal fibroblast cells. There is a potential role of its therapeutic use in mRCC treatment. Future studies should confirm our initial results.
678

Alterações histológicas no epitélio intestinal de juvenis de dourado Salminus brasiliensis alimentados com dietas contendo fontes proteicas vegetais / Histological changes of intestinal epithelium of juveniles dourado Salminus brasiliensis fed diet with vegetables proteins sources alternatives

Thaline Maira Pachelli da Cruz 22 January 2018 (has links)
Restrições econômicas e ambientais trazem a necessidade de substituir a farinha de peixe em dietas de organismos aquáticos por matérias-primas menos dispendiosas de origem vegetal. Entretanto, tais fontes proteicas vegetais possuem fatores antinutricionais que podem ter efeitos negativos sobre o sistema digestório dos peixes, alterando a saúde e, em consequência, a produção. O objetivo deste trabalho foi avaliar a digestibilidade e alterações na histologia do epitélio intestinal de juvenis do Characiforme carnívoro dourado, Salminus brasiliensis, alimentados com dietas contendo farelo de soja (FSO), farelo de algodão (FAl) e farelo de amendoim (FAM) como principais fontes proteicas. Foram conduzidos dois experimentos: digestibilidade (Ensaio I) e histológico (Ensaio II). O Ensaio I foi conduzido em protocolo padrão utilizando dietas práticas adicionadas do marcador inerte óxido de crômio III (CR2O3) e sistema Guelph modificado para coleta de fezes e consequente cálculo dos coeficientes de digestibilidade. No Ensaio II as mesmas fonte proteicas - FSO, FAL e FAM - foram utilizadas em substituição à proteína da farinha de peixe em uma dieta controle com cinco níveis de inclusão: 0 (controle), 25,0 %; 50%; 75,0% e 100%, em um delineamento inteiramente aleatorizado (n=3). O experimento teve a duração de 40 dias, e as coleta de amostras de tecido foram feitas aos 20 e 40 dias. As amostras do intestino posterior foram analisadas quanto às características histológicas e morfológicas, além de quantificação de células caliciformes e análise histomorfométrica do tecido intestinal. Não foram registradas diferenças para os coeficientes de digestibilidade da proteína e energia no ensaio de digestibilidade. O ensaio de desempenho mostrou que a inclusão de FAM e FAL nas dietas melhora o consumo de alimento comparativamente ao FSO Em relação as variáveis histológicas, os níveis que condicionaram alterações significativas nos parâmetros morfométricos foram FSO50 e FOS75. O FSO50 promoveu uma redução das dobras intestinais aos 20 dias, porém aos 40 dias houve aumento na altura das dobras, no espessamento da lâmina-própria e aumento na densidade das células caliciformes. Considerando a microscopia de varredura, sinais acentuados de enterite foram registrados. A alteração na morfologia e histologia do epitélio intestinal foi reflexo da interação de efeitos dos fatores antinutricionais presentes em cada fonte proteica vegetal. Consequentemente, registrou-se menor ganho de peso, crescimento e diminuição da homeostase intestinal, embora os melhores consumos e CAA fossem registrados para os peixes alimentados com FAL e FP. Conclui-se que o FSO causou enterite nos juvenis de dourado e FAL e FAM podem ser utilizados na alimentação de dourado. / Economic and environment constraints have brought the need to replace fishmeal (FM) in diets of aquatic organisms by less expensive feedstuff, especially dietary protein sources. However, such protein sources generally of plant origin, e.g. soybean meal, have antinutritional factors that can negatively affect digestive system of the fish, impairing health and consequently, production. To identify possible effects of plant protein sources in the diets for carnivore fish, this study evaluated effects of various dietary plant protein sources on digestibility, performance, histology of the intestinal epithelium of the carnivore, Neotropical Characin dourado, Salminus brasiliensis, fed plant protein-based diets. A digestibility trial was carried out in standard protocol using diets with inert marker chromium oxide III (Cr2O3) and modified system Guelph for feces. A performance test evaluated the use of three plant protein sources, soybean meal (SBM), cottonseed meal (CTM) and peanut meal (PTM) as surrogate protein source to fishmeal in a practical diet in five levels inclusion: 0 (control); 25.0%; 50.0%; 75.0% and 100%, in a randomized block design (n=3). Samples of tissue of intestinal tract of fish were collected in the distal segment at 20 and 40 days of the feeding period, and analyzed for histological and morphological characteristics. No differences were recorded for apparent digestibility coefficients (ADC) of feedstuff and energy and protein of feedstuffs. Dietary CM and PM elicited better feed consumption comparatively to the other feedstuff, Fish fed diet diet SBM50 presented reduction of intestinal folds at 20 days, but at 40 days had increased folds height, lamina propria thickening, and increased goblet cell density. Considering a scanning microscopy, evident signs of enteritis were registered. The alteration in the morphology and histology of the intestinal epithelium reflected the interaction of effects of the antinutritional factors present in each vegetable protein source, resulting in lower weight gain, growth and decreased intestinal homeostasis, even though best feed consumption and ADC were registered for fish fed CTM and FM.Concluded that SBM caused enteritis and CTM and PM can be used in feeding dourado.
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[en] THE EFFECT OF SURFACE ON NITI FILES SUBJECTED TO TORSION LOADING / [pt] EFEITO DO TRATAMENTO SUPERFICIAL EM LIMAS DE NITI SUBMETIDOS A CARREGAMENTO EM TORÇÃO

JULIO CESAR DE AZEVEDO CARVALHAL 10 February 2005 (has links)
[pt] Limas de NiTi Profile® 25/.04 após sua usinagem não recebem tratamento superficial de polimento gerando pontos concentradores de tensão conseqüente áreas de trinca e fraturas. Avaliou-se o efeito de diferentes condições superficiais de limas endodônticas na resistência à torção. Foram avaliadas e caracterizadas por Microscopia Eletrônica de Varredura dezoito limas rotatórias de NiTi Profile® 25/.04. Utilizou-se 6 limas que não foram submetidas a tratamento químico (Grupo I), 6 limas tratadas com Ácido Nítrico 8% e Ácido Fluorídrico 4% em solução durante 2 minutos (Grupo II) e 6 limas tratadas com a mesma solução porém em tempo de 2 minutos e trinta segundos (Grupo III). Analisaram-se as limas com e sem tratamento superficial carregadas em ensaio de torção e suas fractografias em Microscopia Eletrônica de Varredura. As variáveis avaliadas foram torque aplicado no momento da fratura e ângulo máximo de rotação até a fratura. Os valores obtidos nos ensaios mecânicos referentes ao ângulo máximo de rotação e torque máximo foram analisados estatisticamente através do teste estatístico T-student. Os resultados obtidos permitem concluir que houve diferença estatisticamente significante quanto aos valores de torque máximo entre o Grupo II e Grupo III e ângulo máximo entre os Grupos I e III. / [en] NiTi Profile® 25/.04 files do not undergo surface polishing treatments after machining, and therefore exhibit local stress concentrators and, consequently, areas of cracking and fractures. The effect of different surface conditions on the torsional strength of endodontic files were evaluated. 18 NiTi Profile® 25/.04 rotary files were examined by scanning electron. A group of 6 files (Group I) were not subjected to any chemical treatment, another group of 6 (Group II) were treated for 2 minutes using a solution of 8% Nitric Acid, 4% Flouridic Acid, and a further 6 (Group III) were treated with the same solution fot 2.5 minutes. All the file, with and without treatment, were loaded in a torsion test and fractography of the samples was undertaken by scanning electron microscopy. The variables investigated were, torque at fracture and maximum angle of rotation at fracture. The results obtained in these mechanical tests were subjected to a statistical analysis utilizing the T-Student test. It can be concluded from these results that there was a statistically significant difference between the maximum torque results for groups II and III, and between the maximum angle results for groups I and III.
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Shear Fracture and Delamination in Packaging Materials : A study of Experimental Methods and Simulation Techniques

Islam, Md. Shafiqul January 2016 (has links)
Packages are the means of preservation, distribution and convenience of use for food, medicine and other consumer products. Package opening is becoming complicated in many cases because of cutting cost in design and production of opening techniques. Introduction of new package opening technique, material or geometry for better opening experience, forces new design measurements which require a large number of prototype developments and physical testing. In order to achieve more rapid and accurate design, Finite Element Method (FEM) Simulations are widely used in packaging industries to compliment and reduce the number of physical testing. The goal of this work is to develop the building blocks towards complete package opening simulation. The study focuses on testing and simulation of shear fracture and shear delamination of packaging materials. A modified shear test specimen was developed and optimized by finite element simulation. Test method was validated for High-density polyethylene (HDPE) and Polypropylene (PP). The developed method has been accepted by international standards organization ASTM. Based on linear elastic fracture mechanics, a geometry correction factor of shear fracture toughness for the proposed specimen was derived. The study concluded that, for ease of opening, HDPE is a more favorable material for screw caps than PP. When performing the experiment with the shear specimen to find essential work of fracture, the ligament length should be varied between twice of the thickness and half of the width of the specimen ligament. Multi-layered thin laminate of Low-density polyethylene (LDPE) and aluminum (Al), also known as Al/LDPE laminate, is another key object addressed in this study. Continuum and fracture testing of individual layers provided the base information and input for numerical modeling. The propagation of an interfacial pre-crack in lamination in Al-LDPE laminate was simulated using several numerical techniques available in the commercial FEM solver ABAQUS, and it was concluded that using the combination of VCCT technique to model the interfacial delamination and coupled elasto-plastic damage constitutive for Al and LDPE substrates can describe interfacial delamination and failure due to necking. It was also concluded that the delamination mode in a pre-crack tip is influenced by the ratio of fracture energy release rate of mode I and II. To address the challenge in quantifying shear energy release rate of laminate with very thin substrate, a convenient test technique is proposed. Additionally, scanning electron microscopic study provided useful information on fractured and delaminated surfaces and provided evidence that strengthened the conclusions of this work. The proposed test methods in this work will be crucial to measure the shear mechanical properties in bulk material and thin substrates. Laminates of Al and LDPE or similar material can be studied using the developed simulation technique which can be effectively used for decision support in early package development.

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