Structural and Catalytic Characterization of La0.6Sr0.4MnO3 Nanofibers for Application in Direct Methane Intermediate Temperature Solid Oxide Fuel Cell Anodes

In the present work, structural and catalytic characterization was performed on La0.6Sr0.4MnO3 (LSM) nanofibers. The LSM nanofibers were obtained using the electrospinning technique. For comparison, LSM powders with identical composition were characterized as well. The LSM powders were prepared through a self-combustion citrate-based procedure. SEM, EDX, XRD, and BET investigations were carried out on both LSM nanofibers and powders, pointing out the different structural features. The LSM nanofibers showed a higher surface area than the LSM powders and a lower presence of strontium oxide on the surface. Results of the H2-Temperature Programmed Reduction (TPR) tests showed evidence of a higher reactivity of the nanofibers compared to the powders. The catalytic characterization was performed utilizing a methane oxidation activity test, revealing a better catalytic performance of the LSM nanofibers: at 800 °C. The methane conversion achieved with the LSM nanofibers was 73%, which compared well with the 50% obtained with powders at 900 °C.

Comparative study on amylosucrases derived from Deinococcus species and catalytic characterization and use of amylosucrase derived from Deinococcus wulumuqiensis

Amylosucrase (ASase; EC 2.4.1.4), a versatile enzyme, exhibits three characteristic activities: hydrolysis, isomerization, and transglycosylation. In this study, a novel ASase derived from Deinococcus wulumuquiensis (DWAS) was identified and expressed in Escherichia coli. The optimal reaction temperature and pH for the sucrose hydrolysis activity of DWAS were determined to be 45 °C and 9.0, respectively. DWAS displays relatively high thermostability compared with other ASases, as demonstrated by half-life of 96.7 and 4.7 min at 50 °C and 55 °C, respectively. DWAS fused with 6×His was successfully purified to apparent homogeneity with a molecular mass of approximately 72 kDa by Ni-NTA affinity chromatography and confirmed by SDS-PAGE. DWAS transglycosylation activity can be used to modify isovitexin, a representative flavone C-glucoside contained in buckwheat sprouts to increase its limited bioavailability, which is due to its low absorption rate and unstable structure in the human body. Using isovitexin as a substrate, the major transglycosylation product of DWAS was found to be isovitexin monoglucoside. The comparison of transglycosylation reaction products of DWAS with those of other ASases derived from Deinococcus species revealed that the low sequence homology of loop 8 in ASases may affect the acceptor specificity of ASases and result in a distinctive acceptor specificity of DWAS.