Deacetylation
Mostrando 13-24 de 257 artigos, teses e dissertações.
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13. Chemical deacetylation natural xanthan (Jungbunzlauer®)
With the aim of adapting a method for removal of acetyl groups from xanthan, reactions of chemical deacetylation were carried out with natural xanthan (Jungbunzlauer®) with variations on the following parameters: biopolymer and alkali concentration (sodium and potassium hydroxide). The deacetylation reaction was performed at 25 ºC for three hours. The prop
Polímeros. Publicado em: 11/02/2011
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14. Purificação e caracterização da quitinase de uva (Vitis vinífera L. cv Red Globe) para a produção de quitosana a partir de quitina de camarão
Chitinase is produced by a wide variety of plants as a defense against peste attacks. In this study, grape chitinases were purified 16 times by fractionation in 80% ammonium sulfate followed by dialysis and filtration. Purified chitinases exhibited enzymatic activity toward chitin azure. The yield of purified chitinase was 229 mg/L with chitinase activity of
Química Nova. Publicado em: 2010
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15. Avaliação da atividade antimicrobiana, mutagênica e toxicidade aguda de derivados anfifílicos da o-carboximetilquitosana / Evaluation of antimicrobial, mutagenic activity and acute toxicity of amphifilic derivatives of O-carboxymethylchitosan
The chitosan (Ch), a semi-synthetic derivative biopolymer obtained by deacetylation of chitin, has attracted the attention of researchers due to its multiple bioactivities such as hemostasis, antimicrobial, biodegradable, and low oral toxicity. Chitosan inhibits the growth of a wide variety of bacteria and fungi showing a broad spectrum of antimicrobial acti
Publicado em: 2010
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16. Identification and detection of a novel human endogenous retrovirus-related gene, and structural characterization of its related elements
Up-regulation of human endogenous retroviruses (HERVs) is associated with many diseases, including cancer. In this study, an H family HERV (HERV-H)-related gene was identified and characterized. Its spliced transcript lacks protein-coding capacity and may belong to the emerging class of noncoding RNAs (ncRNAs). The 1.3-kb RNA consisting of four exons is tran
Genetics and Molecular Biology. Publicado em: 23/10/2009
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17. Synthesis, characterization of biocompatibility and evaluation of bioadhesion of n-carboxymethylchitosan nanoparticles in hybrid networks with poliacrylic acid / Síntese, caracterização e avaliação da biocompatibilidade e bioadesão de nanopartículas de n-carboximetilquitosana em redes híbridas com ácido poliacrílico
Chitosan nanoparticle complexes with polyacrylic acid have been used in nanotechnology, as they improve pharmacological activity, in chemical and biological terms, and in particular, increase drug bioavailability. The aim of this work is to evaluate the biocompatibility and bioadhesion of N-carboxymethyl derivatives of chitosan (N-CMC) with in situ polymeriz
Publicado em: 2009
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18. Desacetilação de beta-quitina assistida por ultra-som de alta intensidade: estudo dos efeitos da amplitude e do tempo de irradiação e da temperatura da reação / High intensity ultrasound-assisted beta-chitin deacetylation: study on the effects of the ultrasound irradiation amplitude and duration and of the reaction temperature
A reação de desacetilação da beta-quitina assistida por ultra-som de alta intensidade foi estudada e os efeitos da amplitude e da duração da irradiação e da temperatura sobre a eficiência da reação e as características das quitosanas obtidas foram avaliadas. As espectroscopias de ressonância magnética nuclear e no infravermelho foram empregadas
Publicado em: 2009
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19. Estudos de adsorção de tetraciclina em partículas de quitosana
Devido às suas propriedades físico-químicas e biológicas, associadas à abundância e ao baixo custo da matéria-prima, a quitosana tem sido considerada um material de ampla aplicação em diversos campos, tais como em sistemas de liberação de fármacos. Muitas dessas propriedades estão associadas à presença de grupos amino em sua cadeia polimérica
Publicado em: 2009
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20. Contribution to the study of the deacetylation of chitin: studies of the high power assited deacetylation / Contribuição ao estudo da reação de desacetilação de quitina: estudos da desacetilação assistida por ultra-som de alta potência
Quitosana é um polímero de baixa toxicidade, biodegradável e biocompatível, obtido pela desacetilação heterogênea de quitina, que é um polissacarídeo encontrado abundantemente na biomassa. Em meios aquosos de acidez moderada, a quitosana também exibe comportamento de polieletrólito catiônico, reunindo, assim, características que favorecem a sua
Publicado em: 2008
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21. Obtenção e caracterização de α-quitina e quitosanas de cascas de Macrobrachium rosembergii
The shells of Macrobrachium rosenbergii were submitted to deproteinization (Dp) and demineralization (Dm) aiming the extraction of α-chitin. The different parts of the shells were processed independently by carrying out sequence 1 (Dp/Dm) and sequence 2 (Dm/Dp). Both sequences allowed the extraction of chitins with low contents of calcium and magnesium, reg
Química Nova. Publicado em: 2008
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22. Estudo da expressão dos genes de classe I das histonas desacetilases (HDACs 1,2,3 e 8) em Leucemia Linfóide Aguda de crianças e adolescentes / Class 1 Histone Deacetylases Gene Expression in Childhood Acute Lymphoblastic Leukemia
Acute Lymphoblastic Leukemia (ALL) is a heterogeneous disease with distinct biologic and prognostic groups. In addition to genetic alterations, epigenetic processes play an important role in carcinogenesis, among which histone acetylation/deacetylation is crucial for chromatin modulation structure and transcriptional activity. Histone acetylation is regulate
Publicado em: 2008
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23. Bioatividade de quitosana produzida por Mucor rouxii no controle de Listeria monocytogenes em produto cÃrneo
In last years consumers has demanded for safe foods, especially regarding their microbiological contamination, being still worrying with the damages posed by microbial foodborne diseases, as well as the side effects related to the use abusive use of synthetic additives added to foods, particularly to meat products. In this perspective, the study of new natur
Publicado em: 2008
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24. Competitive adsorption of copper and mercury ions on natural and crosslinked chitosan membranes / Adsorção competitiva dos ions cobre e mercurio em membranas de quitosana natural e reticulada
Recent investigations have described chitosan, a linear polysaccharide obtained from deacetylation of chitin, as a suitable biopolymer to remove heavy metal ions from wastewater, since the amino and hydroxyl groups present in its structure can act as chelating sites. Several methods have been used to modify natural chitosan, such as crosslinking with glutara
Publicado em: 2008