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321.
为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。  相似文献   
322.
The inhibition of arylamine N‐acetyltransferase (NAT) activity by ellagic acid was determined in a human colon tumor (adenocarcinoma) cell line. Two assay systems were performed, one with cellular cytosols (9000g supernatant), the other with intact colon tumor cell suspensions. The NAT activity in a human colon tumor cell line was inhibited by ellagic acid in a dose‐dependent manner in both types of examined systems: i.e. the greater the concentration of ellagic acid in the reaction, the greater the inhibition of NAT activities in both systems. The data also indicated that ellagic acid decreased the apparent K m and V max of NAT enzymes from human colon tumor cells in both the systems examined. This report is the first demonstration which showed ellagic acid affect human colon tumor cell NAT activity.  相似文献   
323.
To assess the exposure doses of PM2.5 and to investigate its chemical components for the subpopulation (i.e., school children and industrial downwind residents), simultaneous sampling of indoor and outdoor PM2.5 was conducted at an elementary school close to traffic arteries and a residence located in the downwind area of a steel plant in metropolitan Guangzhou in 2010. Chemical components, i.e., organic carbon, elemental carbon and 6 water soluble ions were analyzed in PM2.5. A survey was also conducted to investigate the time-activity patterns of the school children and the industrial downwind residents. Indoor and outdoor PM2.5 were 63.2 ± 20.1 and (76.7 ± 35.8) μg/m3 at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m3 in the community, respectively. Indoor PM2.5 was found to be highly related to outdoor sources, and stationary sources were the significant contributors to PM2.5 at both sites. The daily average doses of PM2.5 for the school children at the school (D children) and the industrial downwind residents in the community (D residents) were (7.6 ± 1.9) and (36.1 ± 36.8) μg/kg-day, respectively. The daily average doses of particulate organic mass and SO4 2? were the two most abundant chemical components in PM2.5. PM2.5 exposure for the school children was contributed by indoor and outdoor environments by 48.8 and 51.2 %, respectively; for the industrial downwind residents, the contributions were 66.0 and 34.0 %, respectively. Age and body weight were significantly and negatively correlated with D children, while age, body weight and education level were significantly and negatively correlated with D residents; gender was not a significant factor at both cases.  相似文献   
324.
A comprehensive experimental investigation for an inclined ( $60^{\circ }$ to vertical) dense jet in perpendicular crossflow—with a three-dimensional trajectory—is reported. The detailed tracer concentration field in the vertical cross-section of the bent-over jet is measured by the laser-induced fluorescence technique for a wide range of jet densimetric Froude number $Fr$ and ambient to jet velocity ratios $U_r$ . The jet trajectory and dilution determined from a large number of cross-sectional scalar fields are interpreted by the Lagrangian model over the entire range of jet-dominated to crossflow-dominated regimes. The mixing during the ascent phase of the dense jet resembles that of an advected jet or line puff and changes to a negatively buoyant thermal on descent. It is found that the mixing behavior is governed by a crossflow Froude number $\mathbf{F} = U_r Fr$ . For $\mathbf{F} < 0.8$ , the mixing is jet-dominated and governed by shear entrainment; significant detrainment occurs and the maximum height of rise $Z_{max}$ is under-predicted as in the case of a dense jet in stagnant fluid. While the jet trajectory in the horizontal momentum plane is well-predicted, the measurements indicate a greater rise and slower descent. For $\mathbf{F} \ge 0.8$ the dense jet becomes significantly bent-over during its ascent phase; the jet mixing is dominated by vortex entrainment. For $\mathbf{F} \ge 2$ , the detrainment ceases to have any effect on the jet behavior. The jet trajectory in both the horizontal momentum and buoyancy planes are well predicted by the model. Despite the under-prediction of terminal rise, the jet dilution at a large number of cross-sections covering the ascent and descent of the dense jet are well-predicted. Both the terminal rise and the initial dilution for the inclined jet in perpendicular crossflow are smaller than those of a corresponding vertical jet. Both the maximum terminal rise $Z_{max}$ and horizontal lateral penetration $Y_{max}$ follow a $\mathbf{F}^{-1/2}$ dependence in the crossflow-dominated regime. The initial dilution at terminal rise follows a $S \sim \mathbf{F}^{1/3}$ dependence.  相似文献   
325.
研究常用增塑剂邻苯二甲酸二丁酯(di-n-butyl phthalate,DBP)对农作物生长的影响,为农用地膜及其残留物的环境安全性评估提供实验依据。以蚕豆为试材,DBP处理浓度为0(CK)、9 mmol·L-1、18 mmol·L-1、27 mmol·L-1和36 mmol·L-1,培养24 h、48 h和72 h后,观测根尖细胞染色体结构变化,测试胚根抗氧化酶活性。结果显示:DBP暴露的蚕豆胚根生长速率减缓;随着DBP暴露时间延长,根尖正在进行分裂的细胞被阻断在有丝分裂前期的比例增加,微核率升高,出现多种类型的染色体畸变;DBP暴露的胚根超氧化物歧化酶(superoxide dismutase,SOD)活性提高5.41%~29.68%,过氧化物酶(peroxidase,POD)活性随DBP浓度增加而递减,过氧化氢酶(catalase,CAT)活性显著降低14.00%~43.08%。结果表明,DBP对蚕豆胚根具有遗传毒性,且能够破坏纺锤丝的结构。  相似文献   
326.
LnSrCoO4对CO和C3H8的氧化性能   总被引:1,自引:0,他引:1  
杨小毛  罗来涛  钟华 《环境化学》2004,23(6):655-658
采用聚乙二醇凝胶法制备LnSrCoO4(Ln=La,Sm)复合氧化物,考察了其对CO和C3H8的氧化反应活性,并运用XRD,BET,TEM和TPD等方法对其进行了表征.结果表明:该类复合氧化物具有四方K2NiF。结构,对CO和C3H8的氧化反应具有不同的催化活性,而LaSrCo04催化活性更好.  相似文献   
327.
Carbonyls emitted from essential oils can affect the air quality when they are used in indoors, especially under poor ventilation conditions. Lavender, lemon, rose, rosemary, and tea tree oils were selected as typical and popular essential oils to investigate in terms of composition, thermal characteristics and fifteen carbonyl constituents. Based on thermogravimetric (TG) analysis, the activation energy was 7.6–8.3 kcal mol?1, the reaction order was in the range of 0.6–0.7 and the frequency factor was 360–2838 min?1. Formaldehyde, acetaldehyde, acetone, and propionaldehyde were the dominant carbonyl compounds, and their concentrations were 0.034–0.170 ppm. The emission factors of carbonyl compounds were 2.10–3.70 mg g?1, and acetone, propionaldehyde, acetaldehyde, and formaldehyde accounted for a high portion of the emission factor of carbonyl compounds in essential oil exhaust. Some unhealthy carbonyl species such as formaldehyde and valeraldehyde, were measured at low-temperature during the vaporization of essential oils, indicating a potential effect on indoor air quality and human health.  相似文献   
328.
介绍了永嘉县电镀废水的产生及排放现状,针对其电镀废水的性质及污染状况,提出了具体的治理措施,并以永嘉县电镀企业现状为参照,从电镀企业污染源控制技术上提出了一些综合电镀污水处理技术方案以及统一规划、统一管理的集中控制建议。  相似文献   
329.
采用脱色菌Citrobacter sp. CK3,以活性红KN-3B染料为处理对象,在厌氧批式反应条件下,系统考察了pH值,温度和染料浓度对脱色反应速度的影响;通过动力学模拟及反应过程中染料的UV-Vis扫描图分析,探讨了脱色反应机理。结果表明:Citrobacter sp. CK3对活性红KN-3B的脱色反应的适宜pH为7~9;脱色反应速度在温度为32℃时达到最大。染料初浓度从57 mg/L逐渐增大到458 mg/L时脱色率逐渐降低。脱色过程中染料的偶氮键发生断裂,脱色反应符合二级反应动力学。  相似文献   
330.
研发了一种基于射流曝气的管式反应设备,考察了负荷和DO对反应器处理效能的影响。实验结果表明,在温度为15℃、DO 6.0 mg/L、有机负荷为1.0 kg COD/(m3.d)、氮负荷为0.30 kg TN/(m3.d)、HRT为8 h的条件下,管式反应器可使生活污水的COD、NH4+-N及TN分别从335 mg/L、105 mg/L及110 mg/L降至43 mg/L、14 mg/L及18 mg/L,去除率分别为87%、86%和83%。DO对反应器脱氮效能影响显著,DO为6 mg/L时,能构建出同步硝化反硝化系统,NH4+-N和TN的去除率分别为96.6%和86.7%。  相似文献   
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