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ABSTRACT The aim of this study was to produce bioethanol from enzymatic hydrolysates of cassava pulp, a by-product of cassava flour manufacturing, using an alcohol-tolerant Saccharomyces cerevisiae strain. First, the best operational condition of the starch hydrolysis process was determined through a complete factorial design (24), with triplicates at the central point. The independent variables evaluated were: the concentrations of α-amylase (Termamyl 2X) and glucoamylase (AMG 300L) and both liquefaction and saccharification times. The most favorable hydrolysis condition in the assay was achieved using 0.517 mL AMG.g starch-1 and 0.270 mL Termamyl.g starch-1, with liquefaction and saccharification times of 1 and 2 h, respectively. The broth obtained at this hydrolysis condition contained a high glucose concentration (160 g.L-1). Once the best reaction conditions were determined, fermentation tests were carried out in a 3 L bioreactor, in a batch system, at 30 °C, 100 rpm and pH 5.5, using 3 g.L-1 (dry biomass) of yeast as inoculum. After 24 h of fermentation, an ethanol concentration of 68 g.L-1 was obtained, with 0.48 ethanol yield and 2.83 g.L-1.h-1 productivity. These results indicate the potential use of cassava pulp, a by-product of cassava flour industries in Brazil, as a raw material for bioethanol production.
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Introduction: Zirconia has been considered an alternative material to titanium for implant manufacturing, however the mechanisms regarding to bone healing in presence of zirconia implants remains poorly known. Objective: The objective of the investigation was to evaluate the bone healing surrounding titanium and zirconia implants in rabbits after 7, 14, 30, 45 and 60 days of implant placement through histological evaluation. Material and methods: Fifteen rabbits were used in this study and randomly subdivided into 5 groups, according to experimental periods. Titanium and zirconia implants were inserted into the right and left tibia, respectively. After healing periods of 7, 14, 30, 45 and 60 days, animals were euthanatized, the implants were removed and the samples were submitted to histological procedures. Results: Our histological results demonstrated similar bone healing surrounding titanium and zirconia implants after 7, 14 and 30 days after implant placement. After 45 days, a trend towards to earlier bone maturation was detected, remaining after 60 days. Inflammatory infiltrate, bone resorption and foreign body reaction were not observed in any periods and groups evaluated. Conclusion: Our findings demonstrated that zirconia and titanium presented a similar pattern of bone healing.