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ObjectiveTo investigate the contamination status of Staphylococcus aureus in food and the presence of enterotoxin genes in Jiading District, Shanghai, and to provide a basis for the prevention and treatment of foodborne Staphylococcus aureus disease.MethodsFrom 2021 to 2023, 15 types of food were sampled for S. aureus testing, and the presence of five enterotoxin genes, including sea⁃see, was tested in the strains.ResultsOut of 705 food samples, 88 (12.48%) were positive for S. aureus. S. aureus was detected in 12 of the 15 food types, with the three food types with the highest positive rates being cold noodles (45.00%), raw poultry (26.25%), and vegetable salads (20.00%). The enterotoxin gene carriage rate was 32.95% in food strains. The carriage rates for sea, seb, and sec were 7.95%, 12.50%, and 14.77%, respectively. Neither sed nor see was detected. The detection rate of strains carrying two types of enterotoxin genes was 2.27%. The enterotoxin carriage rates in strains from vegetables, beverages, and raw meat were 57.14%, 40.00%, and 30.00%, respectively.ConclusionThe S. aureus detection rate in food in Jiading District is much higher than the national average. The enterotoxin gene carriage rates are high, with food strains carrying sea, seb, and sec, with sec being the most prevalent. There is a need to enhance monitoring of S. aureus and enterotoxins, especially in high-risk foods such as noodles, vegetables, and non-packaged beverages.

ObjectiveTo investigate the contamination status， serotype distribution and drug resistance of Salmonella in retail poultry in Jiading District， Shanghai.MethodsFour types of poultry （chicken， duck， goose and pigeon） have been sampled from commercial markets. Salmonella contamination has been isolated and identified using serotype analysis. Furthermore， resistance of isolated Salmonella strains towards 16 commonly used antibiotics has been determined.ResultsA total of 60 Salmonella strains were isolated from 80 poultry samples. The detection rates of Salmonella in pigeon， goose， duck and chicken were 86.67%， 81.82%， 72.73% and 59.38%， respectively. Contamination status has been categorized by storage conditions. Lowest detection rate （65.63%） has been noted in poultry samples under refrigeration storage. The majority serotypes of Salmonella have been revealed as Salmonella typhimurium， Salmonella enteritidis and Salmonella corvallis. Relatively higher drug resistance was discovered with tetracycline， nalidixic acid， ampicillin and chloramphenicol， with drug resistance rate of 60.00%， 58.33%， 50.00% and 48.33%， respectively. Low drug resistance was revealed with cefotaxime. In addition， these Salmonella strains were completely sensitive to imipenem. Significant difference in drug resistance was identified across the types of poultry or Salmonella serotypes. The 11.67% of Salmonella strains were non-resistant to any tested drugs. Multi-drug resistant strains accounted for 46.67% of isolated strains， which were resistant to 13 different antibiotics. Ampicillin-tetracycline or chloramphenirol-cefazolin drug resistance pattern suggested that the Salmonella strain was multi-drug resistant.ConclusionSalmonella contamination remains high in retail poultry in Jiading District， Shanghai. Drug resistance to antibiotics is increasing. Therefore， monitoring and control of Salmonella should be strengthened.

ObjectiveTo investigate the contamination status and drug resistance of Campylobacter spp. in poultry sold in Jiading District， Shanghai.MethodsFour types of poultry meats （chickens， ducks， geese and pigeons） were sampled from commercial markets， and potential Campylobacter spp. contamination was isolated and identified. Furthermore， resistance of isolated Campylobacter spp. to 15 commonly used antibiotics was tested.ResultsTotally 29 Campylobacter jejuni strains and 34 Campylobacter. coli were isolated from 236 commercial poultry samples. The most severe contamination of Campylobacter spp. was found in chicken samples， with a detection rate of 34.04%， while the lowest detection rate of Campylobacter spp. was found in duck （19.67%）. Contamination status was categorized with different storage conditions. The lowest detection rate of 6.67% was noted under frozen condition， while highest detection rate of 41.27% was noted under cold storage. Campylobacter jejuni was completely resistant to cefazolin， ciprofloxacin， nalidixic acid and tetracycline， and Campylobacter coli was completely resistant to cefazolin， cefoxitin and nalidixic acid； Campylobacter spp. showed the lowest resistance to imipenem. Multi-drug resistant strains accounted for 100.00% of the isolated strains. 96.83% of the strains were resistant to more than 5 drugs， with the highest number reaching 14 kinds of antibiotics.ConclusionThere is a significant difference in the contamination status and drug resistance of Campylobacter spp. isolated from four types of poultry meats sold in Jiading District， Shanghai， and the drug resistance is serious. It is strongly recommended that the use of antibiotics should be strictly controlled. Freezing can effectively reduce Campylobacter spp. pollution.

ObjectiveTo investigate the contamination situation， serotype distribution and drug resistance of salmonella in poultry sold in Jiading District， Shanghai.MethodsBetween 2019 and 2020， four types of poultry meat （chicken， duck， goose and pigeon） were sampled from markets， and potential salmonella contamination was isolated and identified via serotyping. Furthermore， resistance detection of isolated salmonella to 13 commonly-used antibiotics was conducted.ResultsA total of 32 salmonella strains were isolated from 156 commercial poultry samples. No salmonella was identified in pigeon samples， while the most severe contamination was detected in goose samples， with a detection rate of 28.00%. Contamination situation was categorized with different storage conditions. The lowest detection rate of 12.90% was noted under cold storage， while the highest rate of 26.67% was detected under frozen condition. The major serotypes of salmonella were Salmonella typhimurium， Salmonella enteritidis and Salmonella Argonne. Relatively higher drug resistance was detected with nalidixic acid and tetracycline， with drug resistance rate of 59.38% and 40.63%， respectively. Low drug resistance was detected with cephalosporins， and no drug resistance was detected with imipenem. Significant difference in drug resistance was noted in the serotype of Salmonella isolated from meat of chicken， duck and goose. Three major salmonella strains had different drug resistance. 21.88% （7/32） of salmonella strains were non-resistant to any tested drugs. Multi-drug resistant strains accounted for 31.25% （10/32） of the isolated strains. At most， salmonella was resistant to 11 kinds of different antibiotics.ConclusionThere is a significant difference in the contamination situation and drug resistance of Salmonella isolated from four types of poultry meat sold in Jiading District， Shanghai. It is strongly recommended that different supervision strategies and management upon classification be implemented.

The utilization of hydrogen-enriched liquefied petroleum gas (LPG) is an effective means of reducing carbon emissions, but the special physical and chemical properties of hydrogen have raised concerns among the public. To delve into the intricate chemical kinetic mechanisms governing the inhibitory effect of CO2 on the explosion of hydrogen-enriched LPG, this study systematically investigated the influence of varying CO2 concentrations (3%, 6%, and 9%) on the explosion characteristics of hydrogen-enriched LPG (hydrogen ratio ranging from 0 to 0.5) within a 20 L spherical explosion chamber. Subsequently, a chemical kinetic analysis was conducted, focusing on the explosion reaction dynamics of the H2/LPG/CO2/Air mixture, encompassing temperature sensitivity assessments and the production rates of key free radicals. The findings reveal that although hydrogen incorporation does not significantly alter the maximum explosion pressure of LPG, it markedly accelerates the explosion reaction rate, posing a challenge for CO2 in effectively inhibiting the explosion of hydrogen-enriched LPG. CO2 functions as a stabilizing third body within the reaction system, diminishing the collision frequency among free radicals, hydrogen molecules, hydrocarbon molecules, and oxygen molecules, thereby slowing down the reaction rate. As the proportion of hydrogen increases, the concentration of ·H radicals, known for their high reactivity, escalates, rapidly completing the propagation phase of the chain reaction and intensifying the overall generation rates of critical free radicals, including ·H, ·O, and ·OH. Notably, the key reaction H + O 2 ⇋ O + O H , which governs the reaction temperature, undergoes significant enhancement, further accelerating the explosion reaction rate and ultimately diminishing the inhibitory efficacy of CO2 against the hydrogenated LPG explosion. Furthermore, as the amount of hydrogen added increases, hydrogen's competitiveness for oxygen within the reaction system markedly improves, attenuating the oxidation of hydrocarbons. Concurrently, the alkane recombination reaction, exemplified by C 3 H 6 + C H 3 (+ M) ⇋ s C 4 H 9 (+ M) , is strengthened. These insights provide valuable understanding of the complex interactions and mechanisms during the explosion of hydrogen-enriched LPG in the presence of CO2, with implications for the safe application of hydrogen-enriched LPG. [ABSTRACT FROM AUTHOR]

When the environmental performance is below the aspiration, will firms make substantive changes? In order to answer this question, based on the behavioral theory of the firm, this paper examines the impact of negative environmental performance feedback on substantive green innovation (GI) and its influencing mechanism. It is found that the negative environmental performance feedback induces substantive GI, which is positively moderated by external regulations (i.e., government environmental regulation and public environmental concern) and internal incentive (i.e., executive equity incentive). Media pressure and risk preference act as mediators in the above promotion effect. Heterogeneity analysis shows that the above promotion effect as well as the moderating effects of external regulations are more pronounced in private firms, while the moderating effect of internal incentive is more pronounced in state‐owned firms. Furthermore, the above promotion and moderating effects are more pronounced after the ESG rating event of SynTao Green Finance Agency. This paper offers new sights into understanding the motives of substantive GI and policy suggestion for promoting firms to achieve sustainable development. [ABSTRACT FROM AUTHOR]