Search

Bacteria were separated from biogas slurry treated by Chlorella vulgaris, and then the interaction between Chlorella vulgaris and bacteria was explored and the effect of algae-bacteria symbiotic system on biogas slurry treatment was discussed. 5 bacteria were separated by flat-plate separation method and were identified by 16S rDNA sequencing technology. They were highly similar to the following bacteria:Pseudomonas alcaliphila, Exiguobacterium, Bacillus amyloliquefaciens, Bacillus subtilis and Bacillus tequilensis. By measuring changes in chlorophyll a of Chlorella vulgaris, it was found that 5 bacteria could promote the growth of chlorella and the effect of Exiguobacterium was most obvious. These single strain were co-cultured with Chlorella vulgaris separately and the purification effect of algae-bacteria symbiotic system on biogas slurry were investigated. The results showed that the consortium of Pseudomonas alcaliphila and Chlorella vulgaris could reduce TP to 0.391 mg·L-1, and its removal rate was the highest(85%). The consortium of Exiguobacterium and Chlorella vulgaris had the best treatment effect on TN and COD, and the removal rate was 64.4% and 72.3% respectively. The removal rates of COD, TN and TP by pure microalgae or pure axenic bacterium were much lower than that of the above two microalgae and bacteria co-culture systems. To summarize, algae-bacteria symbolic system has better effect on sewage treatment than pure culture system and has a good application prospect in sewage treatment.

During serving in orbit, spacecraft will be affected by the radiation environment of the space high-energy charged particles, leading to the performance degradation or even malfunctions of electronic components. The complementary metal oxide semiconductor (CMOS) devices are sensitive to ionization damage. Therefore, it is valuable to research the mechanism of radiation effects on CMOS devices, and is significant to engineering and theory. The CC4013 CMOS integrated circuits are irradiated with 60 MeV Br ions, 5 MeV protons and 1 MeV electrons. Based on the data calculated by Geant4 code, the ionizing absorbed dose induced by 60 MeV Br ions is greatest, and the ionizing absorbed dose induced by 1 MeV electrons is lowest. The degradation of CC4013 device during the irradiation test is in-situ measured with Keithley 4200-SCS semiconductor characteristic system. From the experimental results, the threshold voltage degradation in CC4013 under an exposure of 1 MeV electrons is greatest at the same dose, a little lower under 5 MeV protons, and lowest under 60 MeV Br ions.

Bipolar junction transistors (BJTs), as important electronic components in analog or mixed-signal integrated circuits (ICs) and BiCMOS (Bipolar Complementary Metal Oxide Semiconductor) circuits, are employed in the space environment. Therefore, the research on characteristics and mechanisms of ionization damage in the BJTs is very important. Lower energy electrons are used as irradiation source to study the ionization damage in NPN and PNP transistors. Various bias conditions are imposed on the emitter-base junction to reveal the different bias conditions that contribute to the radiation effect on NPN and PNP transistors during irradiation processing. The semiconductor parameter analyzer, Keithley 4200-SCS, is used to measure the change of electrical parameters of transistors with increasing electron irradiation fluence in situ. Based on the measurement results, we find the degradation of transistors is severe under reverse emitter-base bias, and is lowest under forward emitter-base bias, while it is medium under zero emitter-base bias at a given irradiation fluence.