Hydrogen bonding investigation of poly(3-hydroxybutyrate) / glycol chitosan blends studied by infrared and terahertz spectroscopies

Poly(3-hydroxybutyrate) (PHB)/glycol chitosan (GC) polymer blend was developed as one of the new biopolymer materials. Effects of different PHB / GC concentrations were analysed as a function of the blend compositions by using Fourier transform infrared (FTIR) and terahertz (THz) spectroscopies to investigate the changes in the higher-order structure and bonding of hydrogen. The higher-order structure and hydrogen bonding monitored in this study include the crystalline structure and (C=O…H-C) hydrogen bonding of PHB. The FTIR and THz spectra showed that PHB's higher-order structure transforms into the less-order structure by adding GC without altering the crystalline structure and PHB's intramolecular (C = O ... H-C) hydrogen bonding with increasing GC concentration. Because of the addition of GC, the intensity ratio of THz bands figure out the crystalline dynamics of PHB, the helical structure deformation occurs first followed by the weakening of intramolecular (C = O ... H-C) hydrogen bonding within PHB-PHB molecules. Keywords: Chitosan, higher-order structure, hydrogen bonding, low-frequency vibrational spectroscop

Isomaltulose production using free and immobilized Serratia plymuthica cells

Isomaltulose is a low cariogenic sweetener used as a substitute for sucrose in the food industry. In this study, isomaltulose production by Serratia plymuthica ATCC 15928 was performed using free and immobilized cells. Response Surface Methodology was employed to evaluate the influence of temperature, wet cell mass concentration and sucrose concentration during the conversion of sucrose into isomaltulose by free cells. After 2 h of reaction time in shake flasks, a high production of isomaltulose (85.23%) was obtained with a temperature of 25ºC, wet cell mass of 20% (w/v) and sucrose solution of 25% (w/v). The free cells were reused during seven successive batches and resulted in efficient isomaltulose conversion between 83.74 and 67.37%. The production of isomaltulose by immobilized cells in calcium alginate was studied in a packed bed bioreactor during seven days in a continuous process. A conversion yield of sucrose into isomaltulose between 81.26 and 70.89% was obtained, using immobilized cells in calcium alginate Synth® 2% (w/v), sucrose solution of 35% (w/v), wet cell mass of 30% (w/v) and temperature of 25ºC. The conversion of sucrose into isomaltulose remained high using free cells and using immobilized cells in calcium alginate during the period of execution of the experiments.Key words: Isomaltulose, glucosyltransferase, free cells, immobilized cells, Serratia plymuthica

Aquecimento global : de quem é a culpa?

Monografia (graduação)—Universidade de Brasília, Instituto de Química, 2012.O Ensino Formal tem com meta desenvolver o senso crítico dos alunos. Nessa linha, o ensino de Ciências tem papel importantíssimo, pois fará com que os alunos desenvolvam o conhecimento científico, principalmente quando tratados de assuntos polêmicos. Já que é Sabido que temas polêmicos são algo que auxiliam muito no aprendizado dos alunos. Há trabalhos que apontam nessa linha. Uma dessas linhas é o ensino na abordagem da perspectiva Ciência, Tecnologia e Sociedade – CTS – muito discutida nos dias atuais. Um tema comum nos debates acadêmicos da atualidade é o Aquecimento Global, pois normalmente é apresentado como consequência das atividades humanas. Não apresentando outras visões sobre esse tema, tornado, assim, um tema tão polêmico, algo consensual. Isso é verificado na maioria dos livros didáticos e em ferramentas de buscas de informação eletrônica, como o Youtube. Porém esse cenário está se modificando aos poucos. Tornado sua abordagem importante para a formação dos alunos. Para facilitar a abordagem do tema e instigar os alunos a pesquisarem e formar sua própria opinião sobre o assunto elaboramos um texto para ser utilizado em sala de aulas, com vistas a incentivar o debate

Trend-based Document Clustering for Sensitive and Stable Topic Detection

PACLIC / The University of the Philippines Visayas Cebu College Cebu City, Philippines / November 20-22, 200

Study of different parameters in the production of lytic enzymes

The aim of this work was to study the effects of different parameters in the production of β-1,3 glucanases, proteases and chitinases by Cellulosimicrobium celulans 191, in culture media A, B and C, respectively. The experimental designs employed were 2³ factorial designs, and the factors studied were: initial pH, temperature and rotary shaker speed. The experimental results for the production of β-1,3 glucanase in culture medium A showed maximum activity (0.64 U.mL-1) with an initial pH of 8.5 after 24 hours of fermentation at 33 ºC and 200 rpm. The parameters pH, rotary shaker speed and the interaction of all the parameters presented statistical significance. The experimental results for protease production in culture medium B showed maximum activity (4.25 U.mL-1) with an initial pH of 6.5 after 30 hours of fermentation at 20 ºC and 200 rpm. The pH was the only parameter that presented statistical significance. The experimental results for chitinase production in culture medium C showed maximum activity (7.06 U.mL-1) at an initial pH of 5.5 after 72 hours of fermentation at 25 ºC and 200 rpm. All the parameters and their interactions presented statistical significance. The determination coefficients of the analysis of variance and F tests demonstrated that the linear regression models obtained were significant at a confidence level of 95%.O presente trabalho visou o estudo do efeito de diferentes variáveis na produção de β-1,3 glucanases, proteases e de quitinases pela linhagem Cellulosimicrobium cellulans 191, em meios de cultivo A, B e C, respectivamente. Foram realizados planejamentos fatoriais 2³, e os fatores estudados foram: pH inicial, temperatura e agitação dos frascos. No planejamento experimental para a produção de β-1,3 glucanase em meio de cultivo A foi verificada maior produção da enzima (0,64 U.mL-1) com pH inicial de 8,5 após 24 horas de fermentação a 33 ºC e 200 rpm. Os parâmetros pH, agitação dos frascos e interação entre todos os parâmetros foram estatisticamente significativos. No planejamento experimental para a produção de protease em meio de cultivo B foi verificada maior produção da enzima (4,25 U.mL-1) com pH inicial de 6,5 após 30 horas de fermentação a 20 ºC e 200 rpm. O pH foi o único parâmetro estatisticamente significativo. No planejamento experimental para a produção de quitinase em meio de cultivo C foi verificada maior produção da enzima (7,06 U.mL-1) com pH inicial de 5,5 após 72 horas de fermentação a 25 ºC e 200 rpm. Todos os parâmetros estudados e suas interações foram estatisticamente significativos. Os coeficientes de determinação, as análises de variância e os teste F demonstraram que os modelos de primeira ordem obtidos foram considerados estatisticamente significativos adotando um nível de confiança de 95%.299310Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Produção de isomaltulose, um substituto da sacarose, utilizando glicosiltransferase microbiana

Isomaltulose, a functional isomer of sucrose, is a non-cariogenic reducing disaccharide; has a low glycemic index; selectively promotes growth of beneficial bifidobacteria in the human intestinal microflora; and has greater stability than sucrose in some foods and beverages. Isomaltulose is a nutritional sugar that is digested more slowly than sucrose, and has health advantages for diabetics and nondiabetics. Immobilization techniques, especially entrapment of the cells, are widely used for conversion of sucrose into isomaltulose. Immobilization offers advantages such as minimum downstream processing, continuous operation and reusability of cells. Isomaltulose is currently considered to be a promising sugar substitute

Immobilization of Erwinia sp. D12 Cells in Alginate-Gelatin Matrix and Conversion of Sucrose into Isomaltulose Using Response Surface Methodology

Isomaltulose is a noncariogenic reducing disaccharide and also a structural isomer of sucrose and is used by the food industry as a sucrose replacement. It is obtained through enzymatic conversion of microbial sucrose isomerase. An Erwinia sp. D12 strain is capable of converting sucrose into isomaltulose. The experimental design technique was used to study the influence of immobilization parameters on converting sucrose into isomaltulose in a batch process using shaken Erlenmeyer flasks. We assessed the effect of gelatin and transglutaminase addition on increasing the reticulation of granules of Erwinia sp. D12 cells immobilized in alginate. Independent parameters, sodium alginate concentration, cell mass concentration, CaCl2 concentration, gelatin concentration, and transglutaminase concentration had all a significant effect (P < 0.05) on isomaltulose production. Erwinia sp. D12 cells immobilized in 3.0% (w/v) sodium alginate, 47.0% (w/v) cell mass, 0.3 molL−1 CaCl2, 1.7% (w/v) gelatin and 0.15% (w/v) transglutaminase presented sucrose conversion into isomaltulose, of around 50–60% in seven consecutive batches

Isolation of polymers from Saccahromyces cerevisiae cell wall and evaluation of antioxidant activity of isolated mannan-protein

Yeast cell wall contains polymers glucan and mannan-protein that have received much attention with respect to their biological activities. Conventional isolation process involving treatments with hot alkali and acids cause degradation of these polymers. The aim of this paper was to study a low-degrading process for the isolation of glucan and mannan-protein from S. cerevisiae cell wall comprising physic and enzymatic treatments. Yeast cell glucan was obtained in a purity of 87.4% and a yield of 33.7%. The isolated mannan-protein presented antioxidant activity that was increased after thirty minutes of protease treatment. Antioxidant activity was determined by &#946;-carotene/linoleate model system.322326Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES