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AbstractCiprofloxacin, a broad-spectrum fluoroquinolone, is a bactericidal antibiotic targeting DNA gyrase and DNA topoisomerase IV encoded by the gyrAand parCgenes. Resistance to fluoroquinolones requires the accumulation of multiple mutations including those that alter target genes and increase drug efflux. To examine the development of fluoroquinolones resistance in Vibrio parahaemolyticus, ciprofloxacin induction and selection was used to obtain several resistant V. parahaemolyticusmutants, which showed decreased susceptibilities to quinolones, and increased or decreased susceptibility to other structurally unrelated antibiotics. Quinolone resistance-determining region mutations were characterized, and it was found that gyrAmutations occurred in some of the high-level resistant mutants although qnrwas present in both wild-type susceptible and resistant mutant strains. The mutants showed increased qnrexpression and exposure to sub-inhibitory concentrations of ciprofloxacin caused a further increase in qnrexpression independently of the SOS system. Two mutants demonstrated increased expression of the VmeCD-VpoC pump gene that promotes quinolone efflux. In addition, some of the high-level resistance mutants significantly decreased bacterial fitness. These data suggested that multiple genes contributed to the enhanced ciprofloxacin resistance appeared in V. parahaemolyticusand that acquisition of ciprofloxacin resistance impaired bacterial fitness.

Dividing-wall columns (DWCs) are widely used in the separation of ternary mixtures, but rarely seen in the separation of petroleum fractions. This work develops two novel and energy-efficient designs of lubricant-type vacuum distillation process (LVDP) for the separation of hydroisomerization fractions (HIF) of a hydrocracking tail oil (HTO). First, the HTO hydroisomerization reaction is investigated in an experimental fixed-bed reactor to achieve the optimum liquid HIF by analyzing the impact of the operating conditions. A LVDP used for HIF separation is proposed and optimized. Subsequently, two thermal coupling intensified technologies, including side-stream (SC) and dividing-wall column (DWC), are combined with the LVDP to develop side-stream vacuum distillation process (SC-LVDP) and dividing-wall column vacuum distillation process (DWC-LVDP). The performance of LVDP, SC-LVDP, and DWC-LVDP are evaluated in terms of energy consumption, capital cost, total annual cost, product yields, and stripping steam consumption. The results demonstrates that the intensified processes, SC-LVDP and DWC-LVDP significantly decreases the energy consumption and capital cost compared with LVDP. DWC-LVDP further decreases in capital cost due to the removal of the side stripper and narrows the overlap between the third lube oils and fourth lube oils. This study attempts to combine DWC structure into the separation of petroleum fractions, and the proposed approach and the results presented provide an incentive for the industrial implementation of high-quality utilization of HTO through intensified LVDP.