Despite the reason that genus Acinetobacter works as a grave human pathogen, very few numbers of researches have been done so that term it as a pathogen in respect to fish. As per the current study, isolation of three pathogenic bacterial strains was carried out from infected blunt snout bream (Megalobrama amblycephala Yih), from a farm in Yixing city, Jiangsu province, China, which displayed symptoms like tail-rot, shedding scales and ascites in addition to gentle ulceration on the entire body regardless of size and sex of fish. Taking into account the bases of morphology, varied biochemical tests, 16S rDNA segment and rpoB gene sequence analysis, in addition to phylogenetic study, the pathogenic bacteria was identified as A. pittii. Recursive infectivity experiment validated their pathogenicity. Pathological modifications of blunt snout bream infected with A. pittii were taken into observation. Confirmation of the pathogenicity was additionally made by infectivity studies of zebra fish (Brachydanio rerio) and nematode (Caenorhabditis elegans). The drug resistance of these isolates was also scrutinized. All isolates, recognized as multiple drug resistant strains, showcased resistance to clindamycin, streptomycin, vancomycin, cephalosporins, ampicillin, piperacillin, and trimethoprim-sulfamethoxazole, while showcasing sensitivity to norfloxacin, gentamicin, amikacin, and imipenem. Multi-locus sequence typing of these A. pittii isolates brought to light a new clonal lineage of Acinetobacter leading to fish septicemia outbreaks together with indicating that Acinetobacter stains with the new sequence type 839 may be the dominant clone. This is the first report dealing with the infection caused by A. pittii in fish that suggests that A. pittii has a prospective threat to be encountered by freshwater fish farming in addition to causing human clinical infections.

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The present sensor arrangement in a cubic way for monitoring crack propagation in rock samples exhibits shortfalls of blind monitoring zone and large deviation. This study proposes a double-layered wrap-around sensor network, which enhances the monitoring range and improves the location accuracy of acoustic emission source. Furthermore, based on the polar formation algorithm, acoustic emission source was positioned to explore the propagation of microscopic cracks in cylindrical rock samples and this was further validated by the acoustic emission activity index. The results show that: (1) The double-layered wrap-around sensor network exhibits considerably broader monitoring range and enhanced precision. The simulated fracture formed from cracks of high-energy release had a favorable consistency with the macro-failure surface of rock specimens; (2) During the loading process, acoustic emission activity had a significant positive correlation with signal amplitude and the number of events. In addition, acoustic emission activity of medium-grained sandstone showed a tendency of decreasing-remaining at a low value-increasing-remaining at a high value, which exactly corresponds to the four rock loading stages of compaction, elastic deformation, crack development, and crack connection; (3) rock samples experienced micro-cracking of low energy, micro-cracking of high energy, and crack connection in sequence in the failure process, which shows a high consistency between crack development and acoustic emission activity. Thus, acoustic emission activity could be used as an index for assessing the rock failure state.

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