鸡、猪粪便源大肠杆菌对4种抗生素耐药性的比较

以琼脂稀释法对67株鸡源大肠杆菌及61株猪源大肠杆菌进行最低抑菌浓度(MIC)测定,并以SPSS分别进行卡方检验和Probit模型估算,分析不同来源大肠杆菌耐药差异显著性及不同抗生素的半数抑菌浓度(MIC50),以期对不同畜禽粪便来源的大肠杆菌耐药差异进行详细准确的探讨。结果显示,鸡源大肠杆菌对头孢噻肟、诺氟沙星、环丙沙星和四环素耐药率分别为98.51%、68.66%、56.72%和100%,猪源大肠杆菌对头孢噻肟耐药率为88.52%,对诺氟沙星、环丙沙星和四环素则100%耐药。除四环素,鸡源、猪源大肠杆菌对诺氟沙星、环丙沙星、头孢噻肟的耐受差异显著(P0.05),51%的鸡源大肠杆菌和89%的猪源大肠杆菌均呈4重耐药。SPSS分析结果表明,Probit模型估算结果优于当前MIC50常规计算方法,头孢噻肟、诺氟沙星、环丙沙星和四环素对鸡源大肠杆菌MIC50分别为40.031μg·m L~(-1)、40.020μg·m L~(-1)、2.683μg·m L~(-1)和101.418μg·m L~(-1),对猪源大肠杆菌MIC50分别为8.724μg·m L~(-1)、56.044μg·m L~(-1)、31.214μg·m L~(-1)和130.915μg·m L~(-1)。回归方程显示环丙沙星对鸡源大肠杆菌抑制作用最强;高于40.031μg·m L~(-1)时,诺氟沙星抗菌作用弱于头孢噻肟,低于120.23μg·m L~(-1)时,诺氟沙星抗菌作用强于四环素;头孢噻肟、环丙沙星、诺氟沙星和四环素对猪源大肠杆菌的抑菌作用则呈递减趋势。同时验证了诺氟沙星和环丙沙星属同种作用机制,基于Probit模型计算更简单、快速、直观。研究结果可为畜禽养殖中大肠杆菌的耐药差异监控提供一定的数据基础。     

草莓蚜虫防治用药对蜜蜂的急性毒性与风险评价

为明确草莓蚜虫防治用药对蜜蜂的影响,按照《化学农药环境安全评价试验准则》和《化学品测试方法》要求测定了20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对意大利蜜蜂(Apis mellifera L.)的急性毒性,并采用危害商值(HQ)法进行了风险评价。急性毒性结果显示:20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对蜜蜂的急性经口毒性试验结果(48 h-LD50值)分别为4.47μg a.i.·蜂~(-1)、11.2μg a.i.·蜂~(-1)和0.0601μg a.i.·蜂~(-1),对蜜蜂的急性接触毒性试验结果(48 hLD50值)分别为11.0μg a.i.·蜂~(-1)、13.9μg a.i.·蜂~(-1)和0.643μg a.i.·蜂~(-1)。按《化学农药环境安全评价试验准则》中毒性等级划分标准,20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对蜜蜂的毒性等级分别为中毒、低毒和高毒。风险评价结果表明,22%氟啶虫胺腈SC对蜜蜂存在中等风险(HQ值为1 622),20%啶虫脒SP和10%氟啶虫酰胺WG对蜜蜂的风险为低风险,其HQ值分别为40.3和6.70。因此,草莓生产中可优先选用10%氟啶虫酰胺WG来防治蚜虫,20%啶虫脒SP次之。而使用22%氟啶虫胺腈SC时,应注意采取措施降低其对蜜蜂的毒性风险,以免造成危害。     

氨态氮对菲律宾蛤仔毒理机制研究的内参基因筛选

为了准确和系统地分析NH_3-N对菲律宾蛤仔(Ruditapes philippinarum)毒性的分子机制,并对相关基因的转录组学数据进行验证,利用ge Norm和Normfinder这2种软件,以暴露30 d中不同时间点的鳃组织c DNA为模板,从18S r RNA(18S)、beta-actin(Actin)、beta-tubulin(Tubu)、elongation factor 1-alpha(EF1α)、cyclophilin A(Cy PA)、Ubiquitin(Ub)等6个备选管家基因中,筛选可以稳定表达的内参基因,作为转录组学分析的内参基因。以稀释50倍的鳃组织c DNA模板作为检测模板,ge Norm软件分析获得6对备选内参基因的表达稳定性依次为:EF1αCy PAActinTubuUb18S,较优内参为EF1α和Cy PA;Norm Finder软件分析获得6对备选内参基因的表达稳定性为:EF1αActinTubuCy PAUb18S,最优内参基因为EF1α。为了验证上述筛选结果,分别以EF1α和Cy PA作为内参基因研究unigene1的表达趋势,发现以EF1α为内参基因时,unigene1的q RT-PCR的表达趋势与其转录组表达倍数的变化趋势一致。因此确定NH_3-N暴露菲律宾蛤仔后,鳃组织中表达最为稳定的内参基因为EF1α。     

不同测试方法评估48%毒死蜱乳油对玉米田施药者的人体暴露风险

本研究选取3种不同暴露环境,分别为玉米株高达到施药者膝盖左右(暴露环境1)、达到施药者腰部左右(暴露环境2)和高于施药者身高(暴露环境3),采用手动背负式喷雾器,在这3种暴露环境中施喷48%毒死蜱乳油(EC,稀释500倍),通过贴片法和全身整体测试法(whole body dosimetry,WBD)分析了施药者农药皮肤暴露量(dermal exposure,DE)。依据试验结果,发现在暴露环境1和2中,2种测试方法的农药潜在皮肤暴露量(potential dermal exposure,PDE)无显著性差异,但在暴露环境3中,2种测试方法的PDE之间存在显著性差异(LSD0.05=57.9);对施药者的主要暴露部位进行分析,发现在暴露环境1和暴露环境2中2种测试方法的暴露部位类似,但在暴露环境3中显示,贴片法为手部,全身测试法为上半身(头、颈、前胸、后背及手臂)。使用全身测试法测定PDE同时测定直接皮肤暴露量(actual dermal exposure,ADE),并利用ADE和PDE计算外穿防护服(运动服)渗透率的结果,3种暴露环境分别为4.69%、5.19%和5.54%,比通常假设的防护服或工作服的10%渗透率小。     

The impact of airborne particulate matter on pediatric hospital admissions for pneumonia among children in Jinan,China: A case-crossover study

This study aims to examine the effect of short-term changes in the concentration of particulate matter of diameter ≤2.5 µm (PM_2.5) and ≤10 µm (PM₁₀) on pediatric hospital admissions for pneumonia in Jinan, China. It explores confoundings factors of weather, season, and chemical pollutants. Information on pediatric hospital admissions for pneumonia in 2014 was extracted from the database of Jinan Qilu Hospital. The relative risk of pediatric hospital admissions for pneumonia was assessed using a case-crossover approach, controlling weather variables, day of the week, and seasonality. The single-pollutant model demonstrated that increased risk of pediatric hospital admissions for pneumonia was significantly associated with elevated PM_2.5 concentrations the day before hospital admission and elevated PM₁₀ concentrations 2 days before hospital admission. An increment of 10 μg/m³ in PM_2.5 and PM₁₀ was correlated with a 6% (95% CI 1.02–-1.10) and 4% (95% CI 1.00–1.08) rise in number of admissions for pneumonia, respectively. In two pollutant models, PM_2.5 and PM₁₀ remained significant after inclusion of sulfur dioxide or nitrogen dioxide but not carbon monoxide. This study demonstrated that short-term exposure to atmospheric particulate matter (PM_2.5/PM₁₀) may be an important determinant of pediatric hospital admissions for pneumonia in Jinan, China.

Implications: This study demonstrated that short-term exposure to atmospheric particulate matter (PM_2.5/PM₁₀) may be an important determinant of pediatric hospital admissions for pneumonia in Jinan, China, and suggested the relevance of pollutant exposure levels and their effects. As a specific group, children are sensitive to airborne particulate matter. This study estimated the short-term effects attribute to other air pollutants to provide references for relevant studies.     

TG-DSC and FTIR study on pyrolysis of irradiation cross-linked polyethylene

Irradiation cross-linked polyethylene (PEX) and irradiation cross-linked polyethylene with carbon black filler (CB-PEX) are two types of scraps, generated in electric cable production. Their pyrolysis is studied in this work using instrumental TG\DSC\FTIR techniques and kinetic analysis. The experiments are performed at a constant heating rate of 10 °C/min in nitrogen flow at atmospheric pressure. It is found that the main pyrolysis stage is in the temperature range of 395–503 °C for PEX, and in range of 408–515 °C for CB-PEX. In the main pyrolysis stage, CB-PEX requires more external heat than PEX does. Olefins are the major products of pyrolysis for both materials, but they are quite different in their composition and molecular weight distribution. PEX can be converted almost quantitatively into volatile compounds. CB-PEX has a stronger coking tendency, as well as a larger residue composed of carbon black.     

Effect of heat treatment on sorption of polar and nonpolar compounds to montmorillonites and soils

Batch sorption isotherms of 1,3,5-trichlorobenzene, 1,3,5-trinitrobenzene, and tetracycline to organic-free montmorillonites and soils receiving heat treatment (375°C for 24 h) were compared with those to unheated sorbents. Sorption of the nonpolar 1,3,5-trichlorobenzene to soil was lowered after the removal of humus by heating, consistent with the mechanism of hydrophobic partition into organic matter. For 1,3,5-trinitrobenzene, the enhanced sorption to heated soils was attributed to specific interactions with exchangeable cations facilitated by heating-induced irreversible partial dehydration of the clay interlayer. For tetracycline, an additional mechanism for sorption enhancement could be due to increased exposure of strong complexation sites on clay minerals after removal of the humic coating. These hypotheses were supported by the sorption data to heated and unheated Na-, K-, and Cs-saturated montmorillonites. The combustion method is commonly adopted to measure the content of black carbon in soils and sediments. However, findings from the present study indicate that combustion may greatly modify the structural properties of clay minerals, leading to misinterpreted sorption contributions of different soil components to sorption of polar or ionic compounds.     

Photodegradation of naproxen in water under simulated solar radiation: mechanism,kinetics, and toxicity variation

The main objective of this study was to investigate the degradation mechanism, the reaction kinetics, and the evolution of toxicity of naproxen in waters under simulated solar radiation. These criteria were investigated by conducting quenching experiments with reactive oxygen species (ROS), oxygen concentration experiments, and toxicity evaluations with Vibrio fischeri bacteria. The results indicated that the degradation of naproxen proceeds via pseudo first-order kinetics in all cases and that photodegradation included degradation by direct photolysis and by self-sensitization via ROS; the contribution rates of self-sensitized photodegradation were 1.4 %, 65.8 %, and 31.7 % via ·OH, ¹O₂ and O₂ ^??, respectively. Furthermore, the oxygen concentration experiments indicated that dissolved oxygen inhibited the direct photodegradation of naproxen, and the higher the oxygen content, the more pronounced the inhibitory effect. The toxicity evaluation illustrated that some of the intermediate products formed were more toxic than naproxen.     

Effect of Pseudomonas sp. HF-1 inoculum on construction of a bioaugmented system for tobacco wastewater treatment: analysis from quorum sensing

To better construct a bioaugmented system for tobacco wastewater treatment, activated sludge was inoculated with different concentrations of the nicotine-degrading bacterium Pseudomonas sp. HF-1. The results showed that inoculum concentrations of 0.55?±?0.01 and 1.10?±?0.03 mg/g (dry weight of strain HF-1/dry weight of activated sludge) were best to ensure strain HF-1 survival and successful bioaugmentation. The release pattern of autoinducer (AI) for quorum sensing in the bioaugmented system was also investigated. During the period of HF-1 inoculation, compared with failed bioaugmented systems, AI-2 was significantly increased in the successful systems, suggesting that AI-2-mediated bacterial communication played an important role in the colonization of HF-1. When inoculation of strain HF-1 was stopped, the amount of AI-2 decreased and leveled out in all systems. Notably, there was a greater than threefold increase of short-chain AHLs in failed bioaugmented systems, but no increase in successful ones, implying that the fluctuation of short-chain AHLs could be an indicator of the failure of bioaugmentation. Thus, AI-2-mediated quorum sensing could be implemented to facilitate HF-1 colonization.