Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes

Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

An investigation of safety design practices of metal machines

BACKGROUND: Machinery safety issues are a challenge facing manufacturers who are supposed to create and provide products in a better and faster way. In spite of their construction and technological advance, they still contribute to many potential hazards for operators and those nearby. OBJECTIVE: The aim of this study is to investigate safety aspects of metal machinery offered for sale on Internet market according to compliance with minimum and fundamental requirements. METHODS: The study was carried out with the application of a checklist prepared on the basis of Directive 2006/42/EC and Directive 2009/104/EC and regulations enforcing them into Polish law. RESULTS: On the basis of the study it was possible to reveal the safety aspects that were not met in practice. It appeared that in the case of minimum requirements the most relevant problems concerned information, signal and control elements, technology and machinery operations, whereas as far as fundamental aspects are concerned it was hard to assure safe work process. CONCLUSIONS: In spite of the fact that more and more legal acts binding in the Member Countries of the European Union are being introduced to alleviate the phenomenon, these regulations are often not fulfilled.

Qualitative risk assessment during polymer mortar test specimens preparation - methods comparison

Polymer binder modification with inorganic nanomaterials (NM) could be a potential and efficient solution to control matrix flammability of polymer concrete (PC) materials without sacrificing other important properties. Occupational exposures can occur all along the life cycle of a NM and “nanoproducts” from research through scale-up, product development, manufacturing, and end of life. The main objective of the present study is to analyse and compare different qualitative risk assessment methods during the production of polymer mortars (PM) with NM. The laboratory scale production process was divided in 3 main phases (pre-production, production and post-production), which allow testing the assessment methods in different situations. The risk assessment involved in the manufacturing process of PM was made by using the qualitative analyses based on: French Agency for Food, Environmental and Occupational Health & Safety method (ANSES); Control Banding Nanotool (CB Nanotool); Ecole Polytechnique Fédérale de Lausanne method (EPFL); Guidance working safely with nanomaterials and nanoproducts (GWSNN); Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro, Italy method (ISPESL); Precautionary Matrix for Synthetic Nanomaterials (PMSN); and Stoffenmanager Nano. It was verified that the different methods applied also produce different final results. In phases 1 and 3 the risk assessment tends to be classified as medium-high risk, while for phase 2 the more common result is medium level. It is necessary to improve the use of qualitative methods by defining narrow criteria for the methods selection for each assessed situation, bearing in mind that the uncertainties are also a relevant factor when dealing with the risk related to nanotechnologies field.

Effect of variables on the thickness of an edible coating applied on frozen fish establishment of the concept of safe dipping time

Glazing is a technique used to retard fish deterioration during storage. This work focuses on the study of distinct variables (fish temperature, coating temperature, dipping time) that affect the thickness of edible coatings (water glazing and 1.5% chitosan) applied on frozen fish. Samples of frozen Atlantic salmon (Salmo salar) at -15, -20, and -25 °C were either glazed with water at 0.5, 1.5 or 2.5 °C or coated with 1.5% chitosan solution at 2.5, 5 or 8 °C, by dipping during 10 to 60 s. For both water and chitosan coatings, lowering the salmon and coating solution temperatures resulted in an increase of coating thickness. At the same conditions, higher thickness values were obtained when using chitosan (max. thickness of 1.41±0.05 mm) compared to water (max. thickness of 0.84±0.03 mm). Freezing temperature and crystallization heat were found to be lower for 1.5% chitosan solution than for water, thus favoring phase change. Salmon temperature profiles allowed determining, for different dipping conditions, whether the salmon temperature was within food safety standards to prevent the growth of pathogenic microorganisms. The concept of safe dipping time is proposed to define how long a frozen product can be dipped into a solution without the temperature raising to a point where it can constitute a hazard.

Tribunais nacionais e tutela jurisdicional efetiva: da cooperação à integração judiciária no contencioso da união europeia

Tese de Doutoramento em Ciências Jurídicas (área de especialização em Ciências Jurídicas Públicas).

A educação como empoderamento na ótica do desenvolvimento: uma discussão de modelos

Apresentamos nesta comunicação uma tese de ressignificação da educação como empoderamento tendo como foco uma agenda de desenvolvimento justo, digno e inclusivo, e equacionamos os seus principais tipos ou modelos, partindo do princípio que o empoderamento, pelo facto de remeter para diversas conotações ideológicas, não permite almejar consensos quando se trata de o tomar como sinal distintivo ou imagem de marca de uma educação cuja aposta principal é a promoção de um desenvolvimento humano verdadeiramente empenhado em corresponder às expectativas normativas das pessoas em termos de justiça, respeito, dignidade, liberdade e direitos fundamentais para todos.

Um modelo de programação inteira para a otimização da distribuição do serviço docente

Dissertação de mestrado em Engenharia Industrial

Comunicação Android com câmaras ONVIF e gestão de Perfis de Media

Dissertação de mestrado integrado em Engenharia de Telecomunicações e Informática

Multithreading RTOS processor design

Tese de Doutoramento Plano Doutoral em Engenharia Eletrónica e de Computadores.

Aplicação da metodologia TRIZ a um sistema de aproveitamento de águas pluviais de uma unidade hospitalar

Dissertação de mestrado integrado em Engenharia Civil

Avaliação do potencial económico de implementação da construção em BTC

Dissertação de mestrado integrado em Engenharia Civil

Controlo e limites dos princípios constitucionais da proporcionalidade e da igualdade no contexto da inspeção tributária

Dissertação de mestrado em Direito Tributário e Fiscal

Relevância do recurso de amparo na tutela direta dos direitos fundamentais: um olhar particular sobre a experiência cabo-verdiana

Dissertação de mestrado em Direito Administrativo

Intervenção precoce: as preocupações e os apoios sociais das mães do Vale do Sousa

Dissertação de mestrado em Educação Especial (área de especialização em Intervenção Precoce)