Search

The electrospinning of cellulose acetate (CA) was investigated to develop biodegradable nanostructured membranes for the controlled release of drugs used to treat skin wounds. CA nanofibers were successfully prepared via the electrospinning in the four mixed solvents acetic acid : water; acetone : water; DMAc : acetone; DMAc : acetone : water. Design of experiments (DOE) was applied to see what combinations of parameters could affect the production of electrospun microfibers and nanofibers to optimize the process. The results of this work indicated that both the processing parameters and the solvent mixtures were responsible for the fiber diameter and nanostructure membrane appearance. The optimized condition for each solvent mixture was obtained and compared with each one of the others. The best conditions achieved were dimethylacetamida (DMAc) : acetone with 17% of CA, which provided homogeneous and free bead fibers with an average diameter of 295 nm. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The performance of oxygen scavengers can be influenced by several conditions, such as temperature (T) and relative humidity (RH), which are considered to be the two major factors. Therefore, the development of new scavengers requires the study of their performance, with these conditions varied. In this paper, the response surface methodology (RSM) was used to study the performance of a newly developed oxygen scavenger sachet and to model the influences of T and RH and their interaction on the absorption capacity and rate constant of the developed sachet. Commercial oxygen scavenger sachets were used for comparison purposes. The oxygen absorption capacity and rate constant were evaluated with a 22 factorial design with a central point. The results showed that each absorber sachet presented a different behaviour and there were significant interactions between T and RH; so, the RSM was the most appropriate for these studies. The developed sachet presented a better performance compared with the commercial ones at 23°C and 53% RH, which represents the condition for commercialization at room temperature of foods of intermediary water activity, while in the extreme conditions (100% RH and 37°C) all sachets present a similar absorption capacity. Copyright © 2010 John Wiley & Sons, Ltd.

West Indian cherry (Malpighia glabra L.) and pineapple (Ananas comosus (L.) Meer)juice clarification by cross-flow UF, using polysulphone hollow fiber and ceramic tubular membranes with, respectively, nominal molecular weight cut off values of 100kDaltons and average pore diameters of 0.01mm, were studied. The influence of enzymatic treatment using enzyme concentrations of 20, 100 and 300mg/L, a time of 90min and a temperature of 40ºC for depectinization was verified. The juices were then clarified in a laboratory scale filtration unit, with an effective filtration area of 0.12m² for the polysulphone hollow fiber membrane and of 0.005m² for the ceramic tubular membranes. The influence of enzymatic treatment on viscosity, turbidity and total pectin of the juice, before ultrafiltration, is reported. Membrane performance was evaluated in terms of flow rate and clarity of the permeate. The permeate flow rate of depectinized pineapple juice was higher (30 - 60%) for both membranes. Depectinized West Indian cherry juice presented a lower permeate flow rate for the polysulphone hollow fiber membrane. The increase in permeate flow rate, with the use of the 300mg/L and 100mg/L enzyme concentration was not significant, so it is economically advantageous to ultrafilter depectinized juice, treated with an enzyme concentration of 20mg/L.Foi estudada a clarificação através da ultrafiltração por flow rateo cruzado, dos sucos de acerola (Malpighia glabra L.) e Abacaxi (Ananas comosus (L.) Meer), usando membranas de polisulfona fibra oca e tubular cerâmica com peso molecular de corte de 100kDaltons e diâmetro médio de poro de 0,01mm, respectivamente. A influência do tratamento dos sucos, com concentrações de enzima de 20, 100 e 300mg/L, tempo de tratamento de 90min a temperatura de 40ºC, foi verificada, e então os mesmos foram clarificados numa unidade de ultrafiltração com uma área efetiva de 0,12m² para a membrana de polisulfona e de 0,005m² para membrana cerâmica. A influência do tratamento enzimático foi avaliada em termos da viscosidade, turbidez e pectina total do suco, antes da ultrafiltração. Os desempenhos das membranas foram avaliados em termos de flow rate permeado e claridade do permeado. O flow rate permeado do suco de abacaxi tratado foi mais alto (30 - 60%) para ambas as membranas do que para o suco natural. O suco de West Indian cherry despectinizado apresentou flow rate permeado menor para a membrana de polisulfona. O aumento de flow rate, observado com 300mg/L e 100mg/L de enzima não foi significante, concluindo-se que é vantajoso o tratamento com uma concentração de enzima de 20mg/L.

Porous macrospheres with controlled diameter were produced using N-methylolacrylamide and urea–formaldehyde resins synthesized in our laboratories. Hot silicon oil was used to form the porous macrospheres which were characterized by using infrared spectroscopy (FTIR), scanning electron microscopy, mercury porosimetry and surface area determination (BET). Porous macrospheres of amino-polymers were used as support in immunoassays type ELISA (enzyme linked immunosorbent assay) in which mouse immunoglobulin (IgG) was immobilized, and detected by rabbit anti-mouse immunoglobulin (a-IgG) labeled with horseradish peroxidase. Responses were obtained up to a dilution ratio of 1:4000 of the conjugate standard (1 mg/ml) and 10 μ g/ml of IgG solution to recover the spheres in pH=4.5.

O presente estudo teve como objetivo apresentar as mais recentes tendências do setor de embalagens alimentícias no mercado nacional e internacional. Foram abordados os conceitos de embalagens ativas e inteligentes, assim como suas funções, a composição, o formato, as reações químicas envolvidas, a forma de atuação de alguns tipos de embalagens, aplicações e os benefícios da sua utilização pela indústria de alimentos. Essas embalagens são planejadas e permitem interações com os alimentos a fim de manter a qualidade, a integridade, o frescor e a segurança do produto embalado. As inovações tecnológicas já são estabelecidas e bem aceitas em alguns países e conferem benefícios à conservação de grande variedade de alimentos. No Brasil, essas embalagens são tecnologias emergentes que estão em fase de adaptação no mercado nacional e de desenvolvimento por meio da pesquisa de novos mecanismos que podem ser empregados nas mais diversas aplicações.

West Indian cherry (Malpighia glabra L.) and pineapple (Ananas comosus (L.) Meer)juice clarification by cross-flow UF, using polysulphone hollow fiber and ceramic tubular membranes with, respectively, nominal molecular weight cut off values of 100kDaltons and average pore diameters of 0.01mm, were studied. The influence of enzymatic treatment using enzyme concentrations of 20, 100 and 300mg/L, a time of 90min and a temperature of 40oC for depectinization was verified. The juices were then clarified in a laboratory scale filtration unit, with an effective filtration area of 0.12m2 for the polysulphone hollow fiber membrane and of 0.005m2 for the ceramic tubular membranes. The influence of enzymatic treatment on viscosity, turbidity and total pectin of the juice, before ultrafiltration, is reported. Membrane performance was evaluated in terms of flow rate and clarity of the permeate. The permeate flow rate of depectinized pineapple juice was higher (30 - 60%) for both membranes. Depectinized West Indian cherry juice presented a lower permeate flow rate for the polysulphone hollow fiber membrane. The increase in permeate flow rate, with the use of the 300mg/L and 100mg/L enzyme concentration was not significant, so it is economically advantageous to ultrafilter depectinized juice, treated with an enzyme concentration of 20mg/L.

A absorção é a etapa determinante da recuperação de acetona no Filter Tow, por reduzir a emissão de acetona e trazer melhorias à economia. Por isso, ela constitui o objeto deste estudo, que inclui desde a revisão dos conceitos fenomenológicos, considerando a escolha do melhor modelo de equilíbrio líquido-vapor, passando pela execução dos balanços coerentes de massa e o estabelecimento da Fotografia da situação original, relatando um caso complexo de transposição de pratos para recheios. Contudo, a operação das colunas de absorção é influenciada por outras variáveis de caráter desconhecido, ruídos em relação à fenomenologia, o que se pretende avaliar, justificando-se desenvolver estudo para avaliar seus efeitos. Com o objetivo geral de otimizar absorção, uma análise estatística foi executada a partir do levantamento de dados operacionais, utilizando todas suas variáveis, sejam as fenomenológicas, como os ruídos, com o objetivo específico de obter modelos empíricos que complementem as simulações fenomenológicas, aumentando sua abrangência. Para a execução da análise estatística, os conjuntos de dados históricos foram levantados e validados pelos balanços coerentes de massa e pela Fotografia, o que tornou possível sua evolução, desde a seleção das variáveis, até estabelecer os modelos de regressão, com os quais pode-se obter um novo modo de controle, que estabiliza a operação, possibilitando a otimização. Em termos ambientais, a utilização destes modelos resulta em redução de até 15% das perdas de acetona para o ambiente, como também de consumo energético, com uma economia da ordem de 1 milhão de reais por ano, sem quaisquer custos adicionais. Absorption is the key step of the acetone recovery at Filter Tow production, for reducing the acetone emission and improving economics. For this reason it is the subject of this study, including the revision of phenomenological concepts, considering the choice of the best vapor liquid equilibrium model, passing by the improvement of coherent mass balances and establishing the Photography of the original situation, detailing a complex case of transposition of sieve trays to structured packing. However, the operation of the absorption columns is influenced by other variables, with unknown impacts, noises in relation to the phenomenology, justifying the development of this study, for evaluating them. With the general objective of optimizing the absorption, a statistical analysis is performed from collecting operating data, considering all variables, phenomenological and noises, with the specific objective of getting empirical models complementing the phenomenological simulations, increasing their comprising. For performing the statistical analysis sets of historical data have been collected and validated by coherent mass balances and the Photography, making possible its evolution, from the selection of the variables till establishing the regression models, and with them getting a new control way, which stabilizes the operation, allowing the optimization. In environmental terms, the use of these models results in up to 15% decrease in acetone losses to the environment, as well as power consumption with a saving of approximately 1 million reais per year, without any additional costs.