Abstract Background Antibiotics and antibiotic resistance genes (ARGs) used in intensive animal husbandry threaten human health worldwide; however, the core resistome, mobility of ARGs, and the composition of ARG hosts in animal manure and the following composts remain unclear. In the present study, metagenomic assembly was used to comprehensively decipher the core resistome and its potential mobility and hosts in animal manure and compost. Results In total, 201 ARGs were shared among different animal (layer, broiler, swine, beef cow, and dairy cow) manures and accounted for 86–99% of total relative abundance of ARGs, which mainly comprised multidrug, macrolide-lincosamide-streptogramin (M-L-S), tetracycline, beta-lactam, aminoglycoside, and sulfonamide resistance genes. Moreover, efficient composting reduced the total relative abundance of ARGs in manure from 0.938 to 0.405 copies per 16S rRNA gene; however, it did not have any remarkable effect on the multidrug, sulfonamide, and trimethoprim resistance genes. Procrustes analysis indicated that composting can reduce antibiotic residues and decrease the correlation between antibiotics and resistance genes. Furthermore, the ARG hosts included Proteobacteria (50.08%), Firmicutes (37.77%), Bacteroidetes (6.49%), and Actinobacteria (5.24%). In manure, aminoglycoside resistance genes were majorly found in Enterococcus , Streptococcus , and Enterobacter ; tetracycline resistance genes (TRGs) were found in Pseudomonas , Lactobacillus , and Streptococcus ; and multidrug resistance genes were mainly found in Escherichia coli . In our samples, ARGs were more prevalent in plasmids than in chromosomes. The broad host range and diverse mobile genetic elements may be two key factors for ARGs, such as sul1 and aadA , which could survive during composting. The multidrug resistance genes represented the dominant ARGs in pathogenic antibiotic-resistant bacteria (PARB) in manure, and composting could effectively control PARB. Conclusions Our experiments revealed the core resistome in animal manure, classified and relative quantified the ARG hosts, and assessed the mobility of ARGs. Composting can mitigate ARGs in animal manure by altering the bacterial hosts; however, some ARGs can escape from the removal with the survivor heat-tolerant hosts or transfer to these hosts. These findings will help optimize composting strategies for the effective treatment of ARGs and their hosts in farms.
Abstract Despite the rapid development of urban rail transit in China, there are still some problems in train operation, such as low efficiency and poor punctuality. To realize a proper allocation of passenger flows and increase train frequency, this paper has proposed an improved urban rail transit scheduling model and solved the model with an adaptive fruit fly optimization algorithm (AFOA). For the benefits of both passengers and operators, the shortest average waiting time of passengers and the least train frequency are chosen as the optimization objective, and train headway is taken as the decision variable in the proposed model. To obtain higher computational efficiency and accuracy, an adaptive dynamic step size is built in the conventional FOA. Moreover, the data of urban rail transit in Zhengzhou was simulated for case study. The comparison results reveal that the proposed AFOA exhibits faster convergence speed and preferable accuracy than the conventional FOA, particle swarm optimization, and bacterial foraging optimization algorithms. Due to these superiorities, the proposed AFOA is feasible and effective for optimizing the scheduling of urban rail transit.
Cation substitution is a promising approach to reduce the antisite defects and further improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) cells. In this paper, silver (Ag) has been introduced into Cu2ZnSn(S,Se)4 (CZTSSe) thin film to replace Cu partially and form (Cu1-xAgx)2ZnSn(S,Se)4 (0 ≤ x ≤ 1) (CAZTSSe) alloy films by combination of solution method and a rapid annealing technique. The fundamental properties of the mixed Ag-Cu kesterite compound are systematically reported as a function of the Ag/(Ag+Cu) ratio. The results show that band gap of kesterite CAZTSSe is incessantly increased by adjusting the Ag doping content, indicating that the CAZTSSe alloy film is a potentially applicable bandgap grading absorption layers material to obtain higher CZTSSe device. Furthermore, CAZTSSe alloy films with better electrical performance were also obtained by adjusting the Ag content during film fabrication. Finally, we also observed an increment in open circuit voltage (Voc) by 160 mV and an accompanying rise in device efficiency from 4.24 to 5.95%. The improvement is correlated to the improved grain size and decreased antisite defects of Cu instead of Zn site (CuZn) in the lattice. The Voc enhancement evidences that the solution method is facile and viable to achieve proper cation substitution toward higher efficiency kesterite solar cells. In addition, the CAZTSSe cell also displays better charge collection performance because of the higher fill factor (FF) and power conversion efficiency (PCE). Therefore, it can be concluded that the doping of Ag is a potentially appropriate method to reduce the Cuzn antisite defects of CZTSSe and improve efficiency of CZTSSe device.
Biomass energy can reduce the consumption of fossil fuels and reduce environmental pollution. The project site selection affects the production efficiency and economic benefits. Firstly, this study proposes a macro-site selection decision framework for biomass cogeneration considering carbon emission reduction. Secondly, this paper innovatively uses Nash equilibrium as the coordination goal, and introduces Game Theory to determine the optimal combination weight of Best-Worst Method (BWM) and Criteria Importance Though Intercriteria Correlation (CRITIC). Further thinking is needed to improve the comprehensive closeness measurement method, establish a Technique for Order Preference by Similarity to an Ideal Solution and Grey Relational Analysis (TOPSIS-GRA) site selection model that reflects distance and curve shape, and sort the plans. And then explore the barriers to improving the site selection environment. Finally take five cities in China as an example. The feasibility and the stability of the site selection decision-making framework in practical applications are verified by comparative analysis and weight sensitivity analysis. The results show that carbon emission is the primary barrier factor in the criterion layer. In the sub-criterion layer, transportation costs, carbon emission pressure, carbon benefits, industrial policies, and heating rate are the common obstacle factors in each region. To promote the long-term healthy development of the project, this study provides a theoretical reference for the new construction and expansion of biomass cogeneration projects, and has guiding significance for improving the location suitability of the project.
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