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High stability at acidic environment is required for 1,3-1,4-β-glucanase to function in biofuel, brewing and animal feed industries. In this study, a mesophilic β-glucanase from Bacillus terquilensis CGX 5-1 was rationally engineered through sequence alignment and surface charge engineering to improve its acidic resistance ability. Nineteen singly-site variants were constructed and Q1E, I133L and V134A variants showed better acidic stability without the compromise of catalytic property and thermostability. Furthermore, four multi-site variants were constructed and one double-site variant Q1E/I133L with better stability at acidic environment and higher catalytic property was obtained. The fluorescence spectroscopy and structural analysis showed that more surface negative charge, decreased exposure degree of residue No.1, shifted side chain direction of residue No.133 and the lower total and folding free energy might be the reason for the improvement of acidic stability of Q1E/I133L variant. The obtained Q1E/I133L variant has potential applications in industries.

In image acquisition and communication systems on small or micro platforms, such as small satellite or unmanned aerial vehicle platforms, the imaging system can generate huge amount of image data while communication system can only deliver a very small part of them due to the limited communication bandwidth. In this paper, a novel bandwidth adaptive image communication strategy via similarity based auto-selection is designed to select a certain number of most informative images acquired by the imaging system for transmission, where the number of selected images is adaptive to the communication bandwidth. Specifically, the image that is more distinguishing to previously transmitted images measured by the similarity, instead of the instantly acquired image, is selected. Experimental results on simulated image sequence has demonstrated the effectiveness of the proposed bandwidth adaptive image communication algorithm.

Aiming at the problem of communication blackout in the near-space aviation, a new anti-blackout communication method is proposed based on carrier aggregation of OFDMA and frequency diversity. The plasma sheath covered by the aerocraft is treated as a wireless fading channel. The same message is modulated onto every subcarrier of OFDMA in different frequency band. Then frequency diversity reception is used to improve the robustness of the data link. The analysis and simulation results show that the method could significantly improve the bit error performance of the communication link through the plasma sheath. This research provides an effective and simple way for anti-blackout communications.