氨氮胁迫下菲律宾蛤仔肝胰腺内参基因的筛选

利用荧光定量PCR技术对目标基因进行转录水平分析,选择合适的内参基因作为对照是其前提条件.随着氨氮胁迫菲律宾蛤仔毒性效应的深入研究,需要准确评价氨氮对蛤仔肝胰腺组织基因表达的影响.然而,不同浓度氨氮条件下的菲律宾蛤仔肝胰腺组织的内参基因的筛选尚未报道.本研究以2种不同氨氮浓度暴露菲律宾蛤仔14 d的肝胰腺组织cDNA为...     

基于遥感和GIS的赤水河水质对流域土地利用的响应研究

利用2009年TM影像和11个断面的水质监测数据,同时在缓冲区和子流域尺度上,分析了赤水河流域内土地利用方式与水质指标（溶解氧、高锰酸盐指数、氨氮）之间的相关关系,并建立水质对土地利用结构的空间响应模型。由相关性分析得：从缓冲区尺度到子流域尺度,建设用地与氨氮的相关性由显著正相关变为高度正相关,相关系数达到0836;与高锰酸盐指数的相关性则由普通正相关变为显著正相关,相关系数为0776。耕地与高锰酸盐指数的相关性由显著正相关增加为高度正相关,相关系数达到0913;与氨氮的相关系数也增加到0782;而耕地与溶解氧则由缓冲区尺度的一般负相关变为子流域尺度的显著负相关,相关系数达0609。在缓冲区尺度上,林地与氨氮、高锰酸盐指数呈负相关,相关程度总体上随着缓冲半径的增大而增大;而当研究尺度为依自然属性划分的子流域时,林地与氨氮呈现出显著负相关,相关系数达到0673;与高锰酸盐指数呈现出高度负相关,相关系数达到0822;且在子流域尺度上林地对溶解氧的“汇”的作用才充分表现出来,相关系数达0718。研究结果表明：赤水河流域土地利用方式对水质有重要影响。赤水河流域内的城镇建设用地和耕地对流域水质有着严重的负面影响,承载在其上的城市生活、工业污水和农业面源污染(种养殖)是河流水质污染的重要污染源。林地对流域的水质污染有重要的缓解作用。总体上,各水质参数与土地利用类型间的相关性在子流域和缓冲区两种尺度下表现出一致的规律,但这种相关性在子流域尺度下表现的更为显著。研究成果可为赤水河流域的水污染防治、土地利用方式优化提供科学依据,并为同类研究提供借鉴     

苯酚降解菌生物转化吲哚及甲基吲哚的特性

为探索吲哚类废水的资源化处置效果,考察了苯酚降解菌对吲哚及甲基吲哚的生物转化行为,从土壤中分离筛选苯酚降解菌,结合16S rRNA序列分析对菌株进行鉴定;利用菌株休眠细胞对吲哚及甲基吲哚进行生物转化,采用液相色谱-质谱联用分析其转化产物,并结合响应曲面法对吲哚转化合成靛蓝的条件进行优化。结果表明:筛选得到的1株苯酚降解菌YC为Pseudomonas菌属;菌株YC的休眠细胞可对吲哚、5-甲基吲哚、6-甲基吲哚、7-甲基吲哚进行生物转化,生成靛蓝及甲基取代靛蓝。菌株转化吲哚合成靛蓝的最适条件为:生物量OD_(660) 2.50,吲哚50.00 mg·L~(-1),反应体系pH 8.00,在此条件下,靛蓝产量可达到29.78 mg·L~(-1)。综合上述结果,苯酚降解菌Pseudomonas sp. YC能较好地转化吲哚及甲基吲哚合成靛蓝类色素,在吲哚类废水生物修复中具有一定的应用前景。     

Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China

A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.     

Assessment of combined antiandrogenic effects of binary parabens mixtures in a yeast-based reporter assay

To date, toxicological studies of endocrine disrupting chemicals (EDCs) have typically focused on single chemical exposures and associated effects. However, exposure to EDCs mixtures in the environment is common. Antiandrogens represent a group of EDCs, which draw increasing attention due to their resultant demasculinization and sexual disruption of aquatic organisms. Although there are a number of in vivo and in vitro studies investigating the combined effects of antiandrogen mixtures, these studies are mainly on selected model compounds such as flutamide, procymidone, and vinclozolin. The aim of the present study is to investigate the combined antiandrogenic effects of parabens, which are widely used antiandrogens in industrial and domestic commodities. A yeast-based human androgen receptor (hAR) assay (YAS) was applied to assess the antiandrogenic activities of n-propylparaben (nPrP), iso-propylparaben (iPrP), methylparaben (MeP), and 4-n-pentylphenol (PeP), as well as the binary mixtures of nPrP with each of the other three antiandrogens. All of the four compounds could exhibit antiandrogenic activity via the hAR. A linear interaction model was applied to quantitatively analyze the interaction between nPrP and each of the other three antiandrogens. The isoboles method was modified to show the variation of combined effects as the concentrations of mixed antiandrogens were changed. Graphs were constructed to show isoeffective curves of three binary mixtures based on the fitted linear interaction model and to evaluate the interaction of the mixed antiandrogens (synergism or antagonism). The combined effect of equimolar combinations of the three mixtures was also considered with the nonlinear isoboles method. The main effect parameters and interaction effect parameters in the linear interaction models of the three mixtures were different from zero. The results showed that any two antiandrogens in their binary mixtures tended to exert equal antiandrogenic activity in the linear concentration ranges. The antiandrogenicity of the binary mixture and the concentration of nPrP were fitted to a sigmoidal model if the concentrations of the other antiandrogens (iPrP, MeP, and PeP) in the mixture were lower than the AR saturation concentrations. Some concave isoboles above the additivity line appeared in all the three mixtures. There were some synergistic effects of the binary mixture of nPrP and MeP at low concentrations in the linear concentration ranges. Interesting, when the antiandrogens concentrations approached the saturation, the interaction between chemicals were antagonistic for all the three mixtures tested. When the toxicity of the three mixtures was assessed using nonlinear isoboles, only antagonism was observed for equimolar combinations of nPrP and iPrP as the concentrations were increased from the no-observed-effect-concentration (NOEC) to effective concentration of 80 %. In addition, the interactions were changed from synergistic to antagonistic as effective concentrations were increased in the equimolar combinations of nPrP and MeP, as well as nPrP and PeP. The combined effects of three binary antiandrogens mixtures in the linear ranges were successfully evaluated by curve fitting and isoboles. The combined effects of specific binary mixtures varied depending on the concentrations of the chemicals in the mixtures. At low concentrations in the linear concentration ranges, there was synergistic interaction existing in the binary mixture of nPrP and MeP. The interaction tended to be antagonistic as the antiandrogens approached saturation concentrations in mixtures of nPrP with each of the other three antiandrogens. The synergistic interaction was also found in the equimolar combinations of nPrP and MeP, as well as nPrP and PeP, at low concentrations with another method of nonlinear isoboles. The mixture activities of binary antiandrogens had a tendency towards antagonism at high concentrations and synergism at low concentrations.     

Responses of kinetics and capacity of phenanthrene sorption on sediments to soil organic matter releasing

Soil organic matter (SOM) releasing with dissolved organic matter (DOM) formed in solution was confirmed in a sediment/water system, and the effects of SOM releasing on the sorption of phenanthrene on sediments were investigated. Inorganic salt (0–0.1 mol L^?1 NaCl) was used to adjust SOM releasing, and two sediments were prepared, the raw sediment (S1) from Weihe River, Shann’xi, China, and the eluted sediments with and without DOM supernatant remained, termed as S2a and S2b, respectively. The FTIR and ¹H NMR analysis indicate that the low molecular weight hydrophilic SOM fraction released prior to the high molecular weight hydrophobic fraction. As a response, phenanthrene sorption kinetics on S1 showed atypical and expressed as three stages: rapid sorption, pseudo sorption with partial desorption, and slow sorption, thus a defined “sorption valley” occurred in kinetic curve. In all cases, partition dominates the sorption, and sorption capacity (K_d) ranked as S2b > S1 > S2a. Compared with the alterations of sediment characters, DOM solubilization produced by SOM releasing exhibited a greater inhibitory effect on sorption with a relative contribution of 0.67. Distribution coefficients (K_doc) of PHE into DOM clusters were 2.10?×?10⁴–4.18?×?10⁴ L kg^?1, however a threshold concentration of 6.83 mg L^?1 existed in DOM solubilization. The study results will help to clarify PAHs transport and their biological fate in a sediment/water system.     

Investigation on working fluids selection for organic rankine cycles with low-temperature heat sources

The Influence of mixed and pure working fluids on the performance of organic Rankine cycles (ORCs) is discussed. Specifically, the performance of mixed and pure working fluids is analyzed based on certain characteristics of low-temperature heat source and heat sink. A method of selecting binary zeotropic mixed working fluids that match with different heat sinks is introduced. Thermodynamic processes of ORCs for various heat sources are simulated in Matlab. The performance characteristics of pure and mixed working fluids are compared under different inlet temperatures and temperature gradients of sensible heat sources. The results demonstrate that when the initial temperature of a heat source is lower and its temperature gradient is higher, and the temperature gradient of the heat sink is higher, mixed working fluids have better performance than pure working fluids. However, for the opposite heat source and heat sink situations, pure working fluids perform better. Mixtures with low critical temperature components exhibit the best performance among all working fluids when the temperature gradient of the heat source is large. The analysis also shows that introduction of a recuperator may reduce the cycle efficiency when the heat source temperature is low and the temperature gradient of the heat source is large.     

Impact of dissolved oxygen on the production of nitrous oxide in biological aerated filters

Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and microelectrode technology were employed to evaluate the Nitrous oxide (N₂O) production in biological aerated filters (BAFs) under varied dissolved oxygen (DO) concentrations during treating wastewater under laboratory scale. The average yield of gasous N₂O showed more than 4-fold increase when the DO levels were reduced from 6.0 to 2.0 mg?L^–1, indicating that low DO may drive N₂O generation. PCR-DGGE results revealed that Nitratifractor salsuginis were dominant and may be responsible for N₂O emission from the BAFs system. While at a low DO concentration (2.0 mg?L^–1), Flavobacterium urocaniciphilum might play a role. When DO concentration was the limiting factor (reduced from 6.0 to 2.0 mg?L^–1) for nitrification, it reduced NO ₂ ^- -N oxidation as well as the total nitrification. The data from this study contribute to explain how N₂O production changes in response to DO concentration, and may be helpful for reduction of N₂O through regulation of DO levels.

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压电传感器放大电路设计

为了提高压电传感器的固有频率,减小传感器的体积,采用高输入阻抗的仪表放大器,设计研究了用于压电传感器的放大电路,通过改变放大电路输入回路偏置电阻的电阻值,得到了比常规方法更加简单、有效的简单放大电路,实现了小体积下的一体化压电传感器较好的频率响应和良好的线性度。     

纳米SiO2与常规SiO2颗粒对Hela细胞的细胞毒性作用

为了探讨纳米SiO2和常规SiO2颗粒对Hela细胞的细胞毒性作用,采用不同浓度的纳米SiO2和常规SiO2颗粒(0.05、0.1、0.2、0.4、0.8、1.6μg·μL-1)对Hela细胞进行12h染毒,应用MTT法检测细胞毒性效应.研究发现,较低浓度(≤0.2μg·μL-1)的纳米SiO2和常规SiO2对Hela细胞无明显细胞毒性(p>0.05);较高浓度时,纳米SiO2(≥0.4μg·μL-1)和常规SiO2(≥0.8μg·μL-1)对Hela细胞具有明显细胞毒性作用(p<0.01),并且随浓度增大细胞毒性增强;当浓度≥0.4μg·μL-1时,纳米SiO2的细胞毒性明显高于相同浓度的常规SiO2(p<0.05).以上结果表明,纳米SiO2和常规SiO2颗粒均能对Hela细胞产生细胞毒性,且纳米SiO2的细胞毒性强于常规SiO2;低浓度(≤0.2μg·μL-1)的纳米SiO2和常规SiO2具有很好的生物相容性.