Effect Of Immobilized Cells In Calcium Alginate Beads In Alcoholic Fermentation.

Saccharomyces cerevisiae cells were immobilized in calcium alginate and chitosan-covered calcium alginate beads and studied in the fermentation of glucose and sucrose for ethanol production. The batch fermentations were carried out in an orbital shaker and assessed by monitoring the concentration of substrate and product with HPLC. Cell immobilization in calcium alginate beads and chitosan-covered calcium alginate beads allowed reuse of the beads in eight sequential fermentation cycles of 10 h each. The final concentration of ethanol using free cells was 40 g L-1 and the yields using glucose and sucrose as carbon sources were 78% and 74.3%, respectively. For immobilized cells in calcium alginate beads, the final ethanol concentration from glucose was 32.9 ± 1.7 g L-1 with a 64.5 ± 3.4% yield, while the final ethanol concentration from sucrose was 33.5 ± 4.6 g L-1 with a 64.5 ± 8.6% yield. For immobilized cells in chitosan-covered calcium alginate beads, the ethanol concentration from glucose was 30.7 ± 1.4 g L-1 with a 61.1 ± 2.8% yield, while the final ethanol concentration from sucrose was 31.8 ± 6.9 g L-1 with a 62.1 ± 12.8% yield. The immobilized cells allowed eight 10 h sequential reuse cycles to be carried out with stable final ethanol concentrations. In addition, there was no need to use antibiotics and no contamination was observed. After the eighth cycle, there was a significant rupture of the beads making them inappropriate for reuse.33

Kinetics Of Gas-phase Hydrolysis Of Ethyl Acetate Catalyzed By Immobilized Lipase.

Reactions catalyzed by supported enzymes present important advantages when compared with those in aqueous media or organic solvents: separation of enzymes from substrate is easily accomplished, enzyme stability may be improved, and control of the reaction products is more accurate. We present the experimental results of the kinetic study of ethyl acetate hydrolysis in gaseous phase catalyzed by a commercial immobilized lipase (Lipozyme IM; Novo Nordisk). The hydrolysis reaction was studied as a function of ethyl ester and water partial pressure at a constant temperature of 318 K. The amount of biocatalyst used was varied between 100 and 300 mg, and the reaction was studied in a flow-through glass microreactor. Under the conditions used, water was an important parameter in the gas-phase reaction. Activation energy was 24.8 kJ/mol and the overall order of reaction was one. Finally, a Bi-Bi reaction mechanism is proposed.13623-3

Heterogeneous biocatalysis in solid/gas phase: principles and applications.

Enzymatic conversion of gaseous substrates into products in aquo-restricted media, using enzymes or whole cells (free and immobilized) as biocatalysts, constitutes a promising technology for the development of clearer processes. Solid-gas systems offer high production rates for minimal plant sizes, allow important reduction of treated volumes, and permit simplified downstream processes. In this review article, principles and applications of solid-gas biocatalysis are discussed. Comparisons of its advantages and disadvantages with those of the organic- and aqueous-phase reactions are also presented herein

HEPATIC STEATOSIS ASSESSMENT:

ContextLiver transplantation is one of the last viable resources for patients with end-stage liver disease. Many strategies are been used to improve the number of available organs and overcome waiting list delay. However, hepatic steatosis is one of the mainly concerns when organs are consider to transplantation due to it is importance as a risk factor for primary dysfunction. Surgeons play an important role to decide each organ will be accept or decline and its righteous allocation.ObjectiveRetrospectively evaluate the surgeon assessment of steatosis degree and its confrontation with further histopathologic findings.MethodsWe analyzed 117 patients underwent deceased liver transplantation for end-stage liver disease in University Hospital Walter Cantideo, Fortaleza, CE, Brazil. A matrix table was organized to estimate the categorical data observed. We clustered the subjects into mild (0%–30%) and moderate (30%-60%) steatosis degree under the clinical criteria of organ suitability for transplantation. We categorized the organs as suitable organ for transplant and as non-suitable organ for transplant. Evaluations between the two first assessments, before perfusion (pre-perfusion) vs biopsy findings and after perfusion vs biopsy findings observations were analyzed and also a comparison between pre-perfusion and after perfusion data was performed.ResultsOn the first assessment, we obtained a 93% of agreement (n = 109) between the two evaluations. On the second assessment, we had an 8% (n = 9) of mistaken allocation. Comparing the observation before (pre-perfusion) and after (after perfusion), we obtained a strong agreement between the surgeons.ConclusionsAlthough our experienced surgeon team, we have wrongly evaluated feasible organs for transplantation. Nonetheless, our faulty percentage is low comparing to worldwide percentage

Preparation, structural characterization and catalytic properties of Co/CeO2 catalysts for the steam reforming of ethanol and hydrogen production

In this paper, Co/CeO2 catalysts, with different cobalt contents were prepared by the polymeric precursor method and were evaluated for the steam reforming of ethanol. The catalysts were characterized by N2 physisorption (BET method), X-ray diffraction (XRD), UV–visible diffuse reflectance, temperature programmed reduction analysis (TPR) and field emission scanning electron microscopy (FEG-SEM). It was observed that the catalytic behavior could be influenced by the experimental conditions and the nature of the catalyst employed. Physical–chemical characterizations revealed that the cobalt content of the catalyst influences the metal-support interaction which results in distinct catalyst performances. The catalyst with the highest cobalt content showed the best performance among the catalysts tested, exhibiting complete ethanol conversion, hydrogen selectivity close to 66% and good stability at a reaction temperature of 600 °C216281289CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçã