Revista Tecnológica

Influência da concentração de substrato na síntese simultânea de Proteases e Amiloglicosidase em cultivo submerso de Aspergillus awamori NRRL 3112 com pré-sacarificado de amido de milho

2024-08-27T22:26:45+00:00

The present study evaluated the influence that the initial substrate concentration had in the submerged culture of Aspergillus awamori NRRL 3112, for the synthesis of amyloglucosidase and protease, with pre-saccharified corn starch. Two assays were carried out, analyzing, among others, the rates of bioconversion. The results indicated that the assay performed with the highest initial substrate concentration presented better performance, with values such as Y_(AMG/S) and Y_(PTS/S) of 33.43 and 294.64 U/g respectively.

Análise analítica da estabilidade de colunas de aço inoxidável submetidas a compressão axial e situação de incêndio

2024-09-26T11:21:58+00:00

Stainless structural steel has been increasingly used in the construction of large buildings due to its physical, mechanical and thermal properties. Unlike carbon steel, stainless steel has good stiffness retention in a situation of high temperatures, thus it becomes relevant to study the behavior of columns, as well as the parameters that influence heat resistance and compression. Columns made with 6 H-type profiles and lengths ranging from 3 to 7 meters were analyzed, within the 60-minute interval of fire exposure described by ISO 834:1999. By means of recommendations of EN 1993-1-2:2005 and EN 1993-1-4:2006, the temperature increase in the profiles and the resistant stress of the columns were determined. Through the results obtained, it is concluded that the temperature increase is lower as the A_m/V ratio decreases. After 60 minutes of exposure to fire, the resistant capacity of the stainless steel columns analyzed decreased by about 85% in relation to the resistance at room temperature.

ADSORÇÃO DE COBALTO POR CINZAS DE FORNO A LENHA PARA ENRIQUECIMENTO DE RAÇÕES ANIMAIS

2024-08-27T22:26:08+00:00

É possível remover micro poluentes de efluentes industriais através da adsorção, processo que consiste na concentração de um soluto na superfície de um sólido. O cobalto, encontrado em efluentes de indústrias têxteis, pode ser eficientemente adsorvido por cinzas vegetais. Para incrementar a produtividade do setor agropecuário, pode-se destinar as cinzas ricas em cobalto, mineral essencial na nutrição bovina, à suplementação de rações animais. Logo, para tal fim, a adsorção foi estudada para ser futuramente aplicável.

Effects of fouling and its aging in shell-and-tube heat exchangers

2024-09-26T11:33:49+00:00

The use of mathematical models to predict the fouling rate and deposition aging in heat exchangers assists in monitoring the performance of this equipment and in the development of strategies for mitigating fouling. In this context, the objective of this paper was to evaluate the impact of these phenomena on the shell and tube heat exchanger performance in a refinery, using the modified Ebert-Panchal model and the two layers aging model. For that purpose, the Scilab environment was used for simulations. The results of this paper were close to the results found in the literature.

Metadados Título do artigo: Análise da contribuição do mecanismo das chaves de cisalhamento em ligações do tipo pilar-viga. Temática: Contribuição dos mecanismos da chave de cisalhamento no alívio de tensões nas ligações semirrígidas do tipo pilar-viga

2024-09-26T11:33:31+00:00

Although the use of shear keys is recommended by NBR 9062:2017, there is little is information about its sizing and application in the interface of the elements of a pillar-beam-type semirrigid connection. Thus, several studies are being developed nationally, seeking to understand the influence of the mechanism of keys as well as determining which parameters should be observed when they are in use. In this work, results obtained in studies that have proven that shear keys increase the strength of the connections are demonstrated, as well as they promote the relief of tensions transferred to concrete corbels and the significant increase in contribution to the cracking landscape, avoiding slipping between parts, with the use of elastomer pads as support material.

Microbial lipases: propitious biocatalysts for various biotechnological applications

2024-09-26T11:33:14+00:00

The use of microbial lipases is very important because they have a broad spectrum of catalytic reactions. Lipases catalyze reactions in aqueous and non-aqueous media and have advantages when compared to chemical catalysts, due to their specificity, enantioselectivity and stability at pH and temperature. The interest in research for microbial lipases occurs because of their applicability in various sectors and industries, such as food and beverage production, cosmetics, pharmaceuticals, surfactants, dairy products, treatment of effluents containing oils and fats, biofuels, among others. Biocatalysts can be obtained by submerged fermentation (SF) or solid-state fermentation (SSF), which has advantages over SF, because it is possible to use agroindustrial waste as substrate or growth support for microorganisms, becoming an alternative to reduce production costs. SSF is a promising technology for enzyme production, because besides using low-cost substrates, the biocatalyst can be produced in a more concentrated form, facilitating its recovery from the culture medium when necessary. Thus, this paper intends to discuss and review studies on microbial lipases, with direct application of the fermented solid (SSF), focusing on the main microorganisms, substrates and supports used in SSF, applicability of lipases in several industrial sectors, besides presenting conversion results using different microorganisms or/and substrates.

Comparative study between methods of calculating the equivalent load in prestressed hyperestatic beams

2024-09-18T18:40:14+00:00

In most cases of cast-in-place hyperstatic concrete beams, where obviously supports are restricted, the hyperstatic actions can be significant and should be considered in a design. To simplify the manual calculation of prestressed continuous beams and obtain good accuracy considering the inversion of prestressed cables on the supports, this work aims to show the simplest and most accurate method for calculating the equivalent load on prestressed beams. For this, an example of a continuous beam will be solved considering three different methods of calculating equivalent loads, which were presented in Naaman (2004), Thomaz (2009) and Skaf and Stucchi (1995). All results will be analyzed considering the method presented in Naaman (2004) as the most accurate method. And the conclusion obtained is that the simplest, most practical and with good precision method considering the manual calculation is the one presented in Skaf and Stucchi (1995).

Chemical composition and color analysis of BRSMG Caravera rice in relation to urea sources and dosages

2024-09-26T11:32:55+00:00

Rice is an essential food for the diet of the Brazilian population. Parboiling and nitrogen fertilization are processes which aim to improve the physical-chemical composition of these grains. The objective of this study was to evaluate the chemical composition as well as the color of unparboiled and parboiled rice fertilized with policote and kimcoat urea in dosages of 40, 80, and 120 ha^-1. When it comes to the chemical composition, the parboiled rice presented higher levels of moisture, ash, and crude fiber. It also presented low lipid levels, non-nitrogenized extract, and color difference. The nitrogen fertilization strongly impacted the protein levels of rice. It was found that the fertilization with policote and kimcoat urea might have a stronger impact on the protein levels of rice, and that the parboiling process impact further aspects of the chemical composition and color of rice.

Estudo da influência do uso de resíduos de marmoraria no desempenho de concretos

2024-10-10T11:33:34+00:00

Civil construction is one of the sectors that most contributes to the economic and social development of the country, however, it is responsible for a great environmental impact, especially in the generation of waste. In addition to the waste generated from carrying out activities directly linked to civil construction, there is waste from the processing of materials used in the sector, such as ornamental stones. For this reason, it is essential to seek alternatives and new technologies for the reuse of these wastes, in order to minimize the consumption of natural resources and the incorrect disposal of these materials in nature. The work sought to incorporate the marble residues in the concrete, a material with great demand for use, and to make a comparison between the properties of the concrete produced without the incorporation of the residue and those of the concretes with addition and substitution, in the contents of 5%, 7,5%, 10% in relation to the cement. Evaluating the results obtained, considering the physical and mechanical properties of the concretes with the incorporation, a better performance was verified in the samples with 5% of addition in relation to the cement mass, since the values of compressive strength at 28 days were slightly smaller than those of the reference concrete and the porosity presented results of water absorption and void index lower than that of the reference concrete, which provides greater durability to the material. In this way, the work presented interesting results that enable the incorporation of marble residue in the production of concrete, as well as new studies on the subject.