Because of the pollution and energy depletion caused by the burning of fossil energy, the direct glucose fuel cell under alkaline conditions as a clean and efficient device is conducive to the development of human. In this work, we discovered NiCo 2 O 4 and Co 3 O 4 with spinel structure synthesized by the solvothermal method using F127 as the soft template. Then, the structure and electrochemical performance of NiCo 2 O 4 and Co 3 O 4 were systematically studied. The research results of catalytic performance show that NiCo 2 O 4 has better catalytic performances than Co 3 O 4 for the catalytic decomposition of glucose. The specific surface area of NiCo 2 O 4 (123.44 m 2 ·g -1 ) is higher than Co 3 O 4 (49.55 m 2 ·g -1 ), and it has a smaller pore size and larger pore volume. The diffusion coefficient and the sensitivity to glucose of NiCo 2 O 4 is 17.83 times and 4 times than Co 3 O 4 , respectively. And after 30 days of repeated tests, the catalytic activity of the electrode to glucose can still maintain 93.8% of the initial value. This can be attributed to the porous structure of the spinel phase NiCo 2 O 4 , which adds abundant active sites and improves the catalytic activity.
La diffuses into the main lattice of MgCo 2 O 4 (La x -MgCo 2 O 4 ), exposing more Co 3+ active centers: (1) La 3+ , O 2 − , high Co 3+ concentration, high conductivity promote AP decomposition. (2) The highly active La x -MgCo 2 O 4 becomes potential catalyst for CSPs.
The prebiotic fructan inulin can provide energy to organisms via several pathways. One pathway is that inulin fructotransferase (IFTase) firstly converted inulin to III-type difructose anhydride (DFA-III). Then DFA-III is hydrolyzed to inulobiose via difructose anhydride hydrolase (DFA-IIIase). However, only five DFA-IIIases have been reported to date and all of them are from Arthrobacter genus. Whether other microbes except Arthrobacter genus can utilize DFA-III through DFA-IIIase are unknown. In this work, a DFA-IIIase from Duffyella gerundensis A4 (D. gerundensis A4), abbreviated as DgDFA-IIIase, was cloned, expressed, purified, identified, and characterized. It was approximately 50 kDa assayed by SDS-PAGE and showed the highest catalytic activity for DFA-III at pH 6.0 and 35 °C with specific activity of 56 U mg-1. The enzyme was metal-independent and had a high pH stability but low thermostability, which kept only 28% of residual activity after incubation under 50 °C for 3 h. Moreover, Km and kcat/Km for DFA-III was 122 mM and 0.39 mM-1 s-1, respectively. The constructed model of DgDFA-IIIase showed that it has identical residues around substrate at active site with AcDFA-IIIase whose crystal structure has been revealed, indicating that DgDFA-IIIase probably adopts the same catalytic mechanism with the reported AcDFA-IIIase. The work finds that DFA-III can be catalyzed by DFA-IIIase from microorganism of non-Arthrobacter genus, which also extends the enzymatic sources of DFA-IIIase.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The interaction of ethanol with clean and oxygen-preadsorbed Ag polycrystalline surfaces has been studied by photoacoustic spectroscopy and thermal desorption spectroscopy. It is shown that there exists a significant difference in the C-O stretching mode between ethanol and ethoxy. An extremely narrow line feature of the ethoxy C-O mode has been determined for the first time. The adsorption states of both ethanol and ethoxy and the role of the preadsorbed oxygen will be discussed.
Nanostructure arrays such as nanowire, nanopillar and nanocone arrays have been proposed to be promising antireflection structures for photovoltaic applications due to their great light trapping ability. In this paper, the optical properties of Si nanopillar and nanocone arrays in visible and infrared region were studied by both theoretical calculations and experiments. The results show that the Mie resonance can be continuously tuned across a wide range of wavelength by varying the diameter of the nanopillars. However, Si nanopillar array with uniform diameter exhibits only discrete resonance mode, thus can't achieve a high broadband absorption. On the other hand, the Mie resonance wavelength in a Si nanocone array can vary continuously as the diameters of the cross sections increase from the apex to the base. Therefore Si nanocone arrays can strongly interact with the incident light in the broadband spectrum and the absorbance by Si nanocone arrays is higher than 95% over the wavelength from 300 to 2000 nm. In addition to the Mie resonance, the broadband optical absorption of Si nanocone arrays is also affected by Wood-Rayleigh anomaly effect and metal impurities introduced in the fabrication process.
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