ABSTRACT
A SnO2-CuO composite nanofiber was prepared by the coaxial electrospinning method. A new thin-film-type hydrogen sulfide gas sensor was designed by coating SnO2-CuO composite nanofibers onto an alumina ceramic tube with Au electrodes by dip-coating method. The crystalline phase and microstructure of SnO2-CuO composite nanofibers were characterized using X-ray diffraction ( XRD ) and scanning electron microscope ( SEM) . The influence of chemical composition and thickness of sensitive film on the sensitive mechanism and electrochemical characteristic of SnO2-CuO nanofibers were analyzed. The characteristic tests of hydrogen sulfide sensor including sensitive performance, temperature, relative humidity, dynamic response, interference and stability were carried out by WS-30A type multifunction analyzer in gas sensor test system. The results demonstrated that, when the operating temperature was 25℃ and hydrogen sulfide gas concentration increased from 10 to 60 mg/L, the hydrogen sulfide sensor based on C50 composite nanofibers with 70 nm sensitive film thickness had the best linearity (92. 3%) and sensitivity (98. 2%). Besides, its highest response values and relatively humidity level were 1080 and 95%, respectively, and its dynamic response time and recover time were 4 s and 12 s, respectively. This sensor showed good anti-disturbance to the gases, such as CO, NO2 , SO2 , NH3 , CO2 , CH4 and H2 . The response value of the sensor was attenuated about 9. 2% when it was applied continually in the mine about 12 months, and its normal response time was 10. 9 months.
ABSTRACT
TiO2-SnO2 composite nanocrystalline was prepared by the low temperature hydrothermal method. A new film-type ozone sensor was developed by using TiO2-SnO2 composite nanocrystallines transferred onto an alumina ceramic tube with Au electrodes by dip-coating method. The crystalline phase and microstructure of TiO2-SnO2 nanocrystallines were characterized by X-ray diffraction ( XRD) , field emission scanning electron microscope ( FE-SEM) , energy dispersive X-ray analysis ( EDAX) and ultraviolet-visible spectrometry ( UV-Vis) . The ozone sensitive mechanism and photoelectrochemical properties of TiO2-SnO2 nanocrystallines were analyzed by using ultraviolet-visible spectrometry and electrochemical method. These characteristic tests of ozone sensor were carried out on the traits of sensitive performance, dynamic response, interference and stability under ultraviolet-visible illumination by the XEDWS-60 A type multifunction analyzer in gas sensor static test system. the conclusion demonstrates that when the ozone sensor based on TiO2-SnO2 composite nanocrystalline ( molar ratio of Ti and Sn is 6 ) was under conditions of 40% relative humidity and 25 ℃operating temperature, when ozone concentration was increased from 0. 1 to 1. 8 μg/L, the best linearity of ozone sensor upon ultraviolet illumination and visible illumination were 97 . 5% and 78 . 5%, the dynamic response time was 2 s and 9 s, the recovery time was 5. 5 s and 15 s. This kind of sensor showed good anti-disturbance to the gases, such as CO, NOx , formaldehyde, acetone, butanol and methanol. The response value of ozone sensor was attenuated about 4 . 7%, when ozone sensor was applied continually on the automobile about 12 months, and its normal time was 8. 5 months.
ABSTRACT
Objective To investigate the differential expression profiles of microRNAs in the liver of 60Co γ-ray irradiated mice using microRNA microarray and to explore their main functions by bioinformatic analysis.Methods After SPF C57BL/6J mice expose to 4 Gy-single whole body radiation,total number of peripheral WBC and the fMNPCE were measured at 3 d.The differentially expressed miRNAs in mouse liver were detected with miRNA microarray,miRNA-124 and miR-34a were confirmed by real time RT-PCR assay.Bioinformatic analysis was applied to explore target genes and the main functions of the differential expressed miRNAs.Results Compared with control group,the total number of peripheral WBC decreased( t = 2.87,P ＜ 0.05 ) ,while the fMNPCE in bone marrow increased ( t =-2.91,P ＜0.05) after 4 Gy γ-ray irradiation.miRNA microarray revealed that 17 miRNAs were differentially expressed,in which 9 up-regulated,8 down-regulated.The expression levels of miR-124 and miR-34a were coincident with the result of real time RT-PCR.GO analysis showed that some pathways including adherens junction and cell cycle were suppressed,while some immune-related pathways were activated.Conclusions miR-34a and miR-194 were involved in the regulation of acute radiation damage,some other miRNAs including miR-124、miR-382 and miR-92a* also played important roles in radiation process.