Physicochemical properties and cell viability of shrimp chitosan films as affected by film casting solvents. I-potential use as wound dressing

: Chitosan solubility in aqueous organic acids has been widely investigated. However, most of the previous works have been done with plasticized chitosan films and using acetic acid as the film casting solvent. In addition, the properties of these films varied among studies, since they are influenced by different factors such as the chitin source used to produce chitosan, the processing variables involved in the conversion of chitin into chitosan, chitosan properties, types of acids used to dissolve chitosan, types and amounts of plasticizers and the film preparation method. Therefore, this work aimed to prepare chitosan films by the solvent casting method, using chitosan derived from Litopenaeus vannamei shrimp shell waste, and five different organic acids (acetic, lactic, maleic, tartaric, and citric acids) without plasticizer, in order to evaluate the effect of organic acid type and chitosan source on physicochemical properties, degradation and cytotoxicity of these chitosan films. The goal was to select the best suited casting solvent to develop wound dressing from shrimp chitosan films. Shrimp chitosan films were analyzed in terms of their qualitative assessment, thickness, water vapor permeability (WVP), water vapor transmission rate (WVTR), wettability, tensile properties, degradation in phosphate buffered saline (PBS) and cytotoxicity towards human fibroblasts using the resazurin reduction method. Regardless of the acid type employed in film preparation, all films were transparent and slightly yellowish, presented homogeneous surfaces, and the thickness was compatible with the epidermis thickness. However, only the ones prepared with maleic acid presented adequate characteristics of WVP, WVTR, wettability, degradability, cytotoxicity and good tensile properties for future application as a wound dressing material. The findings of this study contributed not only to select the best suited casting solvent to develop chitosan films for wound dressing but also to normalize a solubilization protocol for chitosan, derived from Litopenaeus vannamei shrimp shell waste, which can be used in the pharmaceutical industry.info:eu-repo/semantics/publishedVersio

Valor nutritivo de refeições coletivas: tabelas de composição de alimentos versus análises em laboratório

A cycle of 13 basic meals lunches, planned and executed at an industrial feeding unit was studied, in order to verify the agreement between the nutritive value estimated by indirect analysis (Tables of chemical composition of foodstuffs), and by direct analysis in the laboratory. Two samples of each meal were taken, one consisting of raw unprocessed food and the other of prepared processed food. The following parameters were evaluated: weight, dry matter, humidity, proteins, lipids, fibers ashes, carbohydrates, calcium, iron and phosphorus. The results suggest that both the composition tables presented a weak correlation for calcium and phosphorus. Comparing processed with unprocessed meals, there was an increase in weight and humidity, and a considerable variation in protein, ash, iron and phosphorus, suggesting interference of the culinary process. The Food Composition Tables present limited reliabity for the estimation of most nutrients in collective, prepared meals.Um ciclo de 13 refeições básicas (almoço), planejadas e executadas em uma Unidade de Alimentação Industrial, foi estudado para verificar concordância entre valor nutritivo estimado por análise indireta (tabelas de composição química de alimentos) e análise direta, em laboratório. Foram tomadas duas amostras de cada refeição, uma com alimentos crus não processada, outra com preparações prontas processadas. Foram analisados: peso, matéria seca, umidade, proteínas, lipídios, fibras, cinzas, carboidratos, cálcio, ferro e fósforo. Os resultados indicam que as tabelas de composição apresentaram correlação fraca para cálcio e fósforo. Na comparação não processada vs. processada nota-se variação considerável para proteínas, cinzas, ferro e fósforo, sugerindo interferência do processamento culinário, sugerindo que as tabelas apresentam confiabilidade limitada

proposta de sequência didática para ensino de dilatometria com utilização de paródia

O ensino de Física pode ser associado a atividades que levam à memorização de informações, fórmulas, estruturas e conhecimentos que limitam a aprendizagem, desmotivando o aluno quanto à Física. Os recursos didáticos são considerados elementos essenciais no trabalho dos conteúdos escolares com os alunos, pois permite o contato com diversas formas de aprendizagem, cuja aplicação permeia aspectos motivacionais, estimulantes, desafiadores e colaboradores. Nesse sentido, objetiva-se no trabalho relatar a utilização de paródias como estratégia de ensino e aprendizagem para abordagem de conteúdos de Física, dando enfoque ao uso da contextualização. “Para Ribas e Guimarães (2004, p. 2), quando o aluno sente prazer na atividade proposta pelo professor, a aprendizagem e o processo cognitivo de construção do conhecimento são estimulados”. Segundo os autores, a construção de conhecimentos significativos está ligado a algo que chama atenção e que revela coisas com as quais o indivíduo identifica-se e que pode despertar sensações ou emoções. Para eles, a base de tal reflexão está associada ao estímulo da crítica e a vivência de cada um. Assim, “...o uso da música na forma de paródias tem a possibilidade de quebrar a rotina escolar baseada no modelo tradicional de ensino, possibilitando momentos de alegria e descontração durante a aula, estimulando a atenção e a responsabilidade necessárias à aprendizagem” (SILVEIRA; KIOURANIS, 2008, p. 29)

Exploring the role of supplier relationship management for sustainable operations: an OR perspective

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of the Operational Research Society on 13/11/2013, available online: https://www.tandfonline.com/doi/full/10.1057/jors.2013.145This paper provides a systems-based approach to the exploration of the relationship and integration between Supplier Relationship Management (SRM) factors as part of a Sustainable Operations Management (SOM) agenda. The authors have chosen electronic procurement (e-Procurement) as a suitable context in this light. Through a review of extant literature, a Systems Archetype (SA) model was developed (based on the ‘Accidental Adversaries’ archetype) and findings from a quantitative pilot study exploring key factors pertinent to e-Procurement SRM were gathered, and hence evaluated against SOM factors. The objective of this research was to describe and visualise the causal interrelationships involved in SRM-SOM through the application of a SA (as an Operations Research tool). The authors believe that this research also provides a unique approach to developing and harnessing the useful and unique properties of Systems Thinking (ST), by attempting to reduce and organise the (generally ad hoc and wide-ranging) sequence of subjective perspectives commonly experienced in causal mapping experiments. The paper builds upon the extant literature, and provides further basis for continuing research in the areas of ST, SAs and the application of operational research to plan sustainable operations