ABSTRACT: Soil microorganisms are influenced by climate change. However, the effect of climate change on soil cultivable bacteria are unclear. In this study, the composition and diversity of the soil cultivable bacterial community were explored by a dilution–plate method, PCR, and 16S rRNA sequencing in a desert steppe of northern China after repeated NH4NO3 amendments and precipitation manipulation for seven years. The experimental treatments were as follows: control (CK), N addition (+N), N addition plus water addition (+N+W), and N addition plus water reduction (+N-W). Among the treatment groups, 11 genera and 17 bacterial species were isolated. Nitrogen addition and precipitation manipulation significantly increased the number of cultivable bacteria in the 0.00-0.30 m layer compared to CK. Compared to +N treatment, the +N+W and +N–W treatments had no significant impact on the number of cultivable bacteria. Compared to the CK community, bacterial communities exposed to the other three treatments did not show shifts in the relative abundance of dominant genera and other cultivable bacteria, except for Pontibacter and Staphylococcus. The treatments +N+W and +N-W significantly modified the relative abundance of Pontibacter and Staphylococcus compared to the +N treatment. Available potassium and phosphorus, and moisture content contributed to the change in the composition of the cultivable bacterial community (p>0.05). Nitrogen addition and precipitation manipulation significantly decreased species richness in the 0.00-0.02 m layer, but they did not affect evenness and the Shannon-Wiener Index in the 0.00-0.30 m layer. This study provides insights into how the composition and diversity of the bacterial community is affected by climate change scenarios.

Abstract Purpose: To investigate the role of PI3k/Akt signal pathway in the protective effects of propofol on intestinal and lung injury induced by intestinal ischemia/reperfusion(I/R). Methods: Male Sprague-Dawley rats were subjected to 45 min of ischemia by occluding the superior mesenteric artery and to 2h of reperfusion to establish the model of I/R. Twenty four rats were randomly divided into four groups: Sham, intestinal I/R (II/R), propofol (P), wortmannin (W). In groups P, W, propofol was injected intravenously and continuously at the onset of reperfusion via infusion pump. PI3K inhibitor (wortmannin) was administered intravenously in group W 25 min before ischemia. Intestinal tissues and lung tissues were obtained for determination of histologic injury, wet/dry weight ratio, malondialdehyde (MDA) levels, superoxide dismutase (SOD) and myeloperoxidase (MPO) activities. Meanwhile, the expressions of caspase-3 and phosphorylated Akt (p-Akt) in intestines and lungs were detected by western blot. Results: Propofol treatment alleviated intestinal and lung morphological changes which were observed in II/R group, Moreover, wet/dry weight ratio, the MDA level, MPO activity and expression of caspase-3 were significantly decreased whereas the SOD activity and p-Akt expression were significantly increased. Notably, the protections were significantly reversed by pretreatment of wortmannin. Conclusion: PI3K/Akt pathway activation play a critical role in the protective effects of propofol on intestinal and lung injury induced by ischemia/reperfusion.

High catalytic activity for CO oxidation can be obtained on TiO2 nanotubes (NTs) -supported copper oxide (CuO/TiO2 NTs). But the relatively low thermal stability limits its practical application. Via cerium oxide modification, catalysts with enhanced catalytic activity and higher thermal stability can be obtained. The prepared materials are characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). Catalytic performance for low-temperature CO oxidation is studied by using a microreactor-GC system. Obtained results indicate that CuO/TiO2 NTs exhibit higher thermal stability and higher catalytic activity for CO oxidation after cerium oxide is added.

Via photoreductive deposition process, platinum-modified TiO2 photocatalysts (Pt/TiO2) with various Pt contents are prepared by using H2PtCl6 and hydrogen titanate nanotubes as precursors. The structures and photocatalytic performances of Pt/TiO2 obtained are characterized. The experimental results indicate that platinum has obvious influence on the structure and photocatalytic performances of the hydrogen titanate nanotubes. The tubular structures of some nanotubes are destroyed during the photoreductive deposition process. It is possible that the hydrogen coming from splitting water over formed Pt/TiO2 results in the breach of nanotubes. The existence of platinum can enhance the photocatalytic performance of titanate nanotubes, and the photocatalytic activity arrives at the highest when the Pt content is 1.5 wt.%.