MAIARA SALLA FERREIRA
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Resumo IPEN-doc 26957 Effect of irradiation on the molar mass of chitosan from crab shells of Charybdis hellerii2017 - FERREIRA, MAIARA S.; MOURA, EDUARDO de; GERALDO, AUREA B.C.The importance of determining the molar mass of polymers is closely related to the size of the chain which is a controlling factor in the evolution of solubility, elasticity, fiber formation and mechanical strength properties. There are several methods used to determine the molar mass and they are divided into relative or absolute. Relative methods as viscosimetry require calibration with samples of molar mass known, whereas absolute methods as osmometry do not require it. The importance of molar mass determination is related to its high influence on the properties of chitosan, such as bacterial activity. There are some studies that show that the use of chitosan is more efficient in the inhibition of bacteria than the use of the oligomers that form the same (NO et al., 2002; HIRANO et al., 1989) and that the molar mass required for the inhibition of microorganisms should be greater than 10000 Da (SHAHIDI et al., 2000). The minimum inhibitory concentration of chitosan ranges from 0.005 - 0.1% and depends on the species of bacteria, the molar mass and the pH of the chitosan preparation (GUAN et al., 2001, NO et al., 2002). The method used in this work was the capillary viscosimetry because it is simple, fast and very efficient. For each sample, four dilutions were performed in order to make the extrapolation and determine the intrinsic viscosity. The average viscosity molar mass (Mw) was determined by the Mark-Houwink-Sakurada equation ([ƞ] = KMav). As one of the results it was observed that the chitosan coming from the crab shell is of low molar mass with a value correspondent about 10 times smaller when compared with the standard. The chitosan obtained with the use of electron beam irradiation also shows a decrease in the molar mass as a function of the increase of the absorbed radiation dose.Artigo IPEN-doc 26276 Ionizing radiation applied to one step conversion from different sources of chitin2019 - FERREIRA, MAIARA S.; MOURA, EDUARDO; GERALDO, AUREA B.C.Chitosan is a polyssacharide obtained from chitin’s molecule deacetylation which is the main constituent of some fungi species and the exoskeleton of crustaceans, insects and mollusks. Frequently the production of chitosan is from the crab shells and shrimps that are byproducts of the fishing industry, so it is highly dependent on seasonality. Therefore, finding new chitin’s sources become important. The amino groups present in chitosan give important biological properties such as biodegradability and biocompatibility, activity/immunological effects and antibacterial healing. The chitosan deacetylation process is an aggressive reaction since it requires the attack of chitineous substrate in hot and high concentrated alkalis solution by 1 to 17 hours. It is possible to reduce reagent concentration and time using high-energy irradiation (gamma rays and electron beam). The advantages of radiation use in high-energy include: the absence of chemical initiators, the process can be performed at room temperature and there is no need for the use of solvents. In this work, crab shell, shrimps, squid glads and blattaria were used in order to compare the quality of chitosan found in each animal source. After pretreatment, which include the steps of demineralization and deproteinization, the samples were irradiated at a dose of 20 kGy (gammacell) in order to reduce the deacetylation time. The chitosan from the used chitin sources was characterized by FTIR analysis and its degree of deacetylation was determined.Resumo IPEN-doc 23067 Correlation of traditional and one-step irradiation process for chitosan production from charybdis hellerii crab shells2017 - FERREIRA, M.S.; MOURA, E.; GERALDO, A.Chitosan is a polysaccharide obtained from chitin’s molecule deacetylation, which is the main composition of certain fungi species and crustaceans and insects exoskeleton. The amino groups present in chitosan give it important biological properties such as biodegradability and biocompatibility, activity/immunological effects and antibacterial healing. The deacetylation of chitin is an aggressive process, which reaction processes in 6 to 8 h under hot concentrated alkali solution. In this work, Charybdis hellerii crab shells were fragmented and pretreated for chitosan production and each conversion step, from in natura material pretreatment to final chitosan,were investigated in detail. Itwas observed dose and dose rate applied as in natura as pretreated chitin influence neither pretreatment process nor chitin deacetylation step; at 20 kGy (from or electron beam sources), the conversion process was performed in 60 minutes. The obtained chitosan presented low weight and deacetylation degree compared to standard chitosan, considering specific irradiation conditions.Dissertação IPEN-doc 22063 Imobilização da quitosana da carapaça de siri Charybdis hellerii em filmes poliméricos a partir de sua obtenção com o uso da radiação ionizante2016 - FERREIRA, MAIARA S.A quitosana é um polisacarídeo obtido pela desacetilação das moléculas de quitina, principal constituinte de alguns fungos e do exoesqueleto de crustáceos e insetos. Os grupos amino presentes na quitosana conferem-lhe importantes propriedades biológicas, como a biodegradação, biocompatibilidade, atividade/efeitos imunológicos e atividade antibacteriana. A desacetilação da quitina é um processo cuja conversão é agressiva, já que exige o ataque da quitina em solução de álcalis em alta concentração e à quente, com duração de 6 a 8 horas. Neste trabalho, carapaças de siri da espécie Charybdis hellerii foi fragmentada e pré-tratada para a obtenção da quitosana e cada etapa, desde o pré-tratamento do material in natura à sua conversão em quitosana, foi investigada detalhadamente. Observou-se que dose e taxa de dose não influenciaram no pré-tratamento ou na etapa de desacetilação da quitina; na dose de 20 kGy (gama ou feixe de elétrons), o processo de conversão teve duração de 60 minutos. A quitosana obtida teve baixa massa molar e grau de desacetilação comparável á quitosana padrão (SA), dependendo das condições de irradiação. Além disso, apresentou inibição da atividade bacteriana tanto livre como imobilizada em substratos poliméricos de polipropileno e de polietileno processados também por radiação ionizante.Resumo IPEN-doc 21915 Estudos dos efeitos da radiação nas propriedades de compósitos HDPE/fibras da casca da castanha do Brasil2013 - FERREIRA, MAIARA S.; MOURA, ESPERIDIANA A.B. deResumo IPEN-doc 21840 Estudos dos efeitos da radiação nas propriedades de compósitos HDPE/fibras da casca da castanha do Brasil2012 - FERREIRA, MAIARA S.; MOURA, ESPERIDIANA A.B. deArtigo IPEN-doc 21148 Evaluation of physical, chemical and irradiation parameters on CRAB shell's chitosan obtention process2015 - FERREIRA, MAIARA S.; MOURA, EDUARDO de; GERALDO, AUREA B.C.Artigo IPEN-doc 20804 PBT/Brazilian clay nanocomposites prepared by melt intercalation: effects of organophilic clay content and ionizing radiation treatment2014 - SARTORI, MARIANA N.; FERREIRA, MAIARA S.; VALENZUELA-DIAZ, FRANCISCO R.; RANGARI, VIJAYA K.; JEELANI, SHAIK; MOURA, ESPERIDIANA A.B.Resumo IPEN-doc 19722 Preparação e caracterização do bio-compósito preparado a partir do polietileno de alta densidade verde e fibra da casca da castanha do Brasil2013 - CAMPOS, REJANE D.; FERREIRA, MAIARA S.; DIAZ, FRANCISCO R.V.; MOURA, ESPERIDIANA A.B.; SEO, EMILIA S.M.Artigo IPEN-doc 18382 Inchamento de argilas organofilicas em solventes orgânicos2012 - PEREIRA, AMANDA C.S.; FERREIRA, MAIARA S.; SARTORI, MARIANA N.; MOURA, ESPERIDIANA A.B.; DIAZ, FRANCISCO R.V.