Urethanase produced by Penicillium variabile was purified through ultrasonication, concentration by polyethylene glycol 20,000, and Superdex G-200 gel filtration chromatography. The molecular weight of urethanase was determined to be around 96 kDa by gel filtration. The purified enzyme showed a single band in SDS-PAGE with the molecular weight of ~13.7 kDa, which suggests that the enzyme has a multimeric structure composed of the same subunits. Peptide map fingerprinting analysis was then carried out by MALDI/TOF-TOF MS. Within the known sequences in NCBI, glucosamine-6-phosphate deaminase and 6-phosphogluconate dehydrogenase get high score as compared with urethanase. Sequence analysis informs that N-terminal sequence of urethanase is GTNTADNDAA. The Minchaelis constant (Km) and maximum reaction rate (Vm) of urethanase are 27.2 mmol/L and 156.25 μmol/L min, respectively. 相似文献
n‐Dodecyltriethoxysilane (DTEOS) modified NaHSO4/MCM‐41 catalysts (silanized catalysts) were synthesized by different impregnation sequences and evaluated in the liquid‐phase dehydration of castor oil. The samples were evaluated by X‐ray diffraction, nitrogen adsorption‐desorption, SEM, TEM, FT‐IR spectroscopy, XPS, 29Si MAS NMR spectroscopy, contact angle measurements, NH3‐TPD, and pyridine‐FT‐IR spectroscopy. The analyses demonstrated that silanization enhanced the hydrophobicity of the catalysts, and the impregnation sequence of silanized catalysts had a significant effect on the NaHSO4 dispersion, surface area, acid distribution, and hydrophobicity of the silanized catalysts. The catalytic activity of the silanized catalysts was much higher than that of NaHSO4/MCM‐41. Among the silanized catalysts, the catalyst prepared by simultaneous impregnation with DTEOS and NaHSO4 showed the highest iodine value of 141.8 [g(I2) per 100 g] and lowest hydroxyl value of 11.3 [mg(KOH) · g–1]. 相似文献
In this letter, we solve three-dimensional time-dependent Newton equations for atoms interacting with a ten-cycle elliptically polarized laser pulse. The ionized electron momentum distributions show a tilt angle between the distribution density peak and the main polarization axis. The tilt angle’s behavior changes with an increasing laser intensity. We show that this behavior change is directly related to the release time of the electron from the atom. 相似文献
Hollow nanocubes of spinel Co3O4 with the dimension of 20 nm were successfully prepared via a facile and reproducible solvothermal route. The structure and morphology of Co3O4 nanoboxes were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) techniques. And a possible growth mechanism of Co3O4 nanoboxes were suggested that solid Co3O4 nanocubes nucleate in-situ and grow epitaxially from hexagonal β-Co(OH)2 precursors with the structural matching relationship of [0 0 1] β-Co(OH)2//[1 1 1] Co3O4, and then solid Co3O4 nanocubes gradually hollow and convert to single-crystal nanoboxes owing to Ostwald ripening. 相似文献
Functional organic dyes have promising prospect in dye-sensitized solar cells as a crucial element, of which sensitizers based on donor-π-acceptor are the most important dyes. On the basis of the structures of the aromatic amine donors such as triphenylamine and indoline, this paper reviews the photoelectric conversion properties of organic sensitizers since 2008, and highlights research work in our laboratory in this area. 相似文献
Assembly of Sn on Cu Nanorods as anode for Li-ion microbatteries was prepared by a two-step electrodeposition design. Firstly, Cu nanorods arrays were grown on copper substrate by anodic aluminum oxide template-assisted growth method. Then, Sn was deposited onto Cu nanorods arrays by galvanostatic deposition. X-ray diffraction and scanning electron microscopy measurements reveal that Cu nanorod arrays are covered with Sn. Electrochemical performances of prepared electrodes were evaluated by charge/discharge cycle measurement. The assembly of Sn on Cu nanorods electrode exhibited highly reversible specific capacity and superior capacity retention resulting from the three-dimensionally nano-architectured design, which exhibits a large surface area, shortened Li-ion diffusion distance, Cu–Sn alloying, and can accommodate the volume expansion of Sn during cycling. Deposition time is an important parameter for fabricating the assembly of Sn on Cu nanorods electrode with suitable structure and morphology.