Antibiotic resistant bacteria are widely spread in environments. However, the compositions of bacteria with antibiotic resistance in subtropical fish pond sediment are still unclear. In present study, to analyze the compositions of norfloxacin resistant bacteria in subtropical fish pond sediments, we selectively cultured the sediment bacteria collected from six subtropical fish ponds located in southern China using the basic medium with 50 µg/ml of norfloxacin, and analyzed their compositions using MiSeq high-throughput sequencing of 16S rRNA gene amplicons. Our results showed that various norfloxacin resistant bacteria existed in the fish pond sediments. And most of them were Gram-negative bacteria. Their spatial distribution was mainly influenced by environmental heterogeneity of the ponds. These results implied that norfloxacin resistance was widespread in Gram-negative bacteria in the fish pond sediments located in southern China. These finding provided reference information to prevent fish infected diseases and to assess the risk of antibiotic resistant bacteria in the fish pond sediments.

The supply of lubrication oil has a great influence on the reliability and efficiency of a scroll compressor, because oil plays a role in lubrication, sealing, and heat transfer in the compressor. In this work, a comprehensive steady and transient analysis on the oil supply system of a high-pressure shell scroll compressor was carried out using a commercial computational fluid dynamics (CFD) program. Various parameters, including pressure difference, compressor rotation speed, oil temperature, bearing clearance, and diameter of the oil gallery, were investigated to find the relations with oil flowrate. Among them, oil temperature and bearing clearance are indicated as the most sensitive, and pressure difference follows. Compressor rotation speed and diameter of the oil gallery are insensitive. Some hydrodynamic parameters can also be obtained in detail, such as pressure drop and oil flow velocity. This CFD analysis has proved to be helpful for the design and optimization of an oil supply system in a scroll compressor.