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| Rotta,Jefferson; Minatti,Edson; Barreto,Pedro Luiz Manique. |
| In this work, the structural, mechanical, diffractometric, and thermal parameters of chitosan-hydroxypropylmethylcellulose (HPMC) films plasticized with sorbitol were studied. Solutions of HPMC (2% w/v) in water and chitosan (2% w/v) in 2% acetic acid solution were prepared. The concentration of sorbitol used was 10% (w/w) to both polymers. This solutions were mixed at different proportions (100/0; 70/30; 50/50; 30/70, and 0/100) of chitosan and HPMC, respectively, and 20 mL was cast in Petri dishes for further analysis of dried films. The miscibility of polymers was assessed by X-ray diffraction, scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The results obtained indicate that the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Films; Chitosan; Hydroxypropylmethylcellulose; Physico-chemical properties. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612011000200026 |
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| Silva,L.A.O; Terrasan,César Rafael Fanchini; Carmona,Eleonora Cano. |
| Background Two xylanases, Xyl I and Xyl II, were purified from the crude extracellular extract of a Trichoderma inhamatum strain cultivated in liquid medium with oat spelts xylan. Results The molecular masses of the purified enzymes estimated by SDS-PAGE and gel filtration were, respectively, 19 and 14 kDa for Xyl I and 21 and 14.6 kDa for Xyl II. The enzymes are glycoproteins with optimum activity at 50°C in pH 5.0-5.5 for Xyl I and 5.5 for Xyl II. The xylanases were very stable at 40°C and in the pH ranges from 4.5-6.5 for Xyl I and 4.0-8.0 for Xyl II. The ion Hg2+ and the detergent SDS strongly reduced the activity while 1,4-dithiothreitol stimulated both enzymes. The xylanases showed specificity for xylan, Km and Vmax of 14.5, 1.6 mg·mL-1 and 2680.2... |
| Tipo: Journal article |
Palavras-chave: Enzyme purification; Physico-chemical properties; Trichoderma inhamatum; Xylanases. |
| Ano: 2015 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582015000400009 |
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