478 research outputs found

    Optimization of clavulanic acid production by Streptomyces daufpe 3060 by response surface methodology

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    Clavulanic acid is a β-lactam antibiotic which has a potent β-lactamase inhibiting activity. In order to optimize its production by the new isolate Streptomyces DAUFPE 3060, the influence of two independent variables, temperature and soybean flour concentration, on clavulanic acid and biomass concentrations was investigated in 250 mL-Erlenmeyers according to a 2² central composite design. To this purpose, temperature and soybean flour (SF) concentration were varied in the ranges 26-34°C and 10-50 g/L, respectively, and the results evaluated utilizing the Response Surface Methodology. The experimental maximum production of clavulanic acid (629 mg/L) was obtained at 32°C and 40 g/L SF after 48 h, while the maximum biomass concentration (3.9 g/L) at 30°C and 50 g/L soybean flour, respectively. These values are satisfactorily close to those (640 mg/L and 3.75 g/L, respectively) predicted by the model, thereby demonstrating the validity of the mathematical approach adopted in this study.Brazilian Research Funding InstitutionsCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

    Sorgo de alto tanino na nutrição e sanidade de tambaquis parasitados por acantocéfalos e monogeneas.

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    Diante das possibilidades do uso do sorgo de alto tanino e da problemática de infestação parasitária nas pisciculturas intensivas, o objetivo deste trabalho foi avaliar níveis de inclusão do sorgo de alto tanino na nutrição e sanidade de tambaquis parasitados oriundos de uma piscicultura no estado do Amazonas

    A fuzzy method for the usability evaluation of nuclear medical equipment

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    To avoid errors when handling nuclear medical equipment, it is important to develop products with a high degree of usability. This can be achieved by performing usability evaluations in the product development process to detect and mitigate potential usability problems. Usability evaluation focuses on how well users can learn and use a product to achieve their goals. Thus, the usability evaluation has become recognized as a valuable complement to the established approaches to design good user interfaces, to reduce incidents and accidents as well the time required to learn how to use the equipment. To gather information about usability, practitioners use a variety of methods that gather feedback from users about an existing interface or plans related to a new interface. A wide range of usability evaluation methods have been proposed, but few methods focus on developing an objective and practical evaluation method for usability. Moreover, the usability evaluations are based on human judgments and most methods cannot fully solve the subjectivity of these evaluations. In order to remedy this deficiency, the purpose of this work is to adopt a Fuzzy Set Theory (FST) approach to establish a method for the usability evaluation of nuclear medical equipment based on usability heuristics for user interface design and international standards for ergonomics of human-system interaction. To exemplify the method we performed a usability evaluating of the Digital Spectrometer ESP 13004 by testing it with representative users. The results showed that the method is a proactive tool to provide a basis for checking usability of medical device interfaces
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