Evaluation of lipase from Burkholderia cepacia immobilized in alginate beads and application in the synthesis of banana flavor (isoamyl acetate)

The alginate in bead forms was used to immobilize Burkholderia cepacia lipase. The microencapsulation technique for lipase entrapment was a 2% (w/v) of sodium alginate concentration prepared by ionic gelation using calcium chloride as the cross-linking agent in a gelling solution. The beads were tested in different solvents as acetone, chloroform, toluene, n-hexane, and n-heptane. Over a 5-day period (120 h), the n-heptane maintained the reasonable (excellent) residual activity of the immobilized lipase. Morphological studies on reused beads and new beads were performed. All beads for isoamyl acetate yield were tested. The reused bead leaches substantially, with a maximum ester yield of 92%. With modifications in the molar ratios, the synthesis of banana flavor (isoamyl acetate) was performed in both the alcohol per acid and acid per alcohol excesses20512333FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2011/19394-

Alternative Liquid-Assisted Sintering of Al/Cu Composites Using Selected Powders of As-Cast Al-Zn Alloy

Al and its alloys constitute one of the most versatile, economical, and attractive materials for a wide range of applications. The 7xxx and 2xxx series alloys achieve the highest mechanical strength among the aluminum alloys. In this investigation, powder metallurgy is used to characterize the microstructural and mechanical properties of a noncommercial Al6Cu5Zn alloy. Initial powder sizes are determined, and the best conditions are obtained for distribution between 75 and 106 μm. The samples are sintered at 585 °C, 600 °C and 615 °C for 0.5, 1.5 h and 3 h. Similar mechanical behavior to that of the as-cast Al-Cu-based alloys is attained (~125 MPa) for the samples sintered at 615 °C for 3 h. In terms of a reduction in energy consumption and in the metal fumes commonly evidenced by foundry applications, Al-Zn powders have the potential to be associated with Al and Cu powders in an Al6Cu5Zn composite constitution

Designing sintering time for a TiSiC compound: a microwave and conventional comparison

Ti3SiC2 has an important role on the resulting mechanical properties, which is based on the ceramic and metallic aspects. The microstructural array of the Ti3SiC2 and its corresponding hardness and mechanical behavior are analyzed. X-ray diffractometry (XRD), microstructural analysis using scanning electron microscopy (SEM-EDS), and densification using Archimedes' principle are used. It is found that the microwave (MW) processing provides higher hardness values and compressive strengths than the conventional (CN) sintered samples, i.e., similar to 8 GPa and similar to 240 MPa, respectively. Also, it is found that the compressive strength to density ratio clearly favors the sample produced using MW processing. This induces that a lightweight effect associated with an environmentally friendly aspect is also attained. It is induced that a Ti3SiC2 compound can be successfully produced by using a microwave treating when a conventional process is compared10415611570FAPESP – Fundação de Amparo à Pesquisa Do Estado De São PauloGrant 16/13352-