Functionalized cubic Ia3d mesoporous silica (FCIMS) with glycidoxypropyl groups was prepared and characterized by powder XRD, N2 adsorption, TGA, FT‐IR spectroscopy, solid state 13C NMR spectroscopy and TEM, and studied as the support for the immobilization of Penicillin G acylase (PGA). The results show that the glycidoxypropyl groups have been chemically bonded to the silicon atoms on the surface of cubic Ia3d mesoporous silica (CIMS). The FCIMS materials possess the mesoporous structure with pore diameter of 8 nm which is ∼ 1 nm less than that of CIMS (9 nm). The influence of the amount of glycidoxypropyl groups on the initial specific activity and operational stability of PGA immobilized on FCIMS were examined for the hydrolysis of penicillin G potassium salt. The results show that PGA has been successfully immobilized covalently on the FCIMS materials, and the initial specific activity of PGA/FCIMS is 835 IU g–1 and PGA/CIMS is 624 IU g–1. After repeated use for 10 times, PGA/FCIMS retains 72 % of its initial specific activity and PGA/CIMS retains only 58 %.
A robust hashing method based on computer-vision techniques is proposed as an improvement to the existing computer-vision based hashing scheme. The cochleagram of the audio is treated as an image, from which Speeded Up Robust Features are extracted as essential features. Non-negative matrix factorisation is used to reduce the features' dimension. In hashing matching, recurrence quantification analysis is performed on the cross recurrence plot that is constructed from the essentialfeatures of two clips to measure their similarity. Experimental results illustrate that the proposed method exhibits superior performance compared to existing techniques in identification rate (under various content preserving manipulations) and computational complexity.
A cold model experimental device was established for studying droplet entrainment in the composite scrubbing-cooling chamber. The effect of the superficial gas velocity, the initial liquid flow velocity of the nozzle, and the radial position of nozzles on droplet entrainment was investigated. The experimental results show that the droplet entrainment increases with the increase of the superficial gas velocity and the flow rate of falling film, but its profile is quite mean in the radial direction in the chamber. The droplet entrainment decreases by about 40% when the number of nozzles increases from two to four. Increasing the nozzle number can make the droplet well distributed and reduce droplet entrainment. Based on the experiment data, an empirical correlation for droplet entrainment fraction is also obtained, as E ∝ Re 1.92 ·We 0.52 . The optimization study for the structure of the scrubbing-cooling chamber can provide some guidance for the industrial application.
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