取代苯胺和苯酚类化合物对大型蚤的毒性及PH值对其毒性的影响

测定了２４个取代苯胺和苯酚类化合物在不同ＰＨ下对大型蚤的２４ｈ半数抑制浓度２４ｈ－ＩＣ５０。结果表明,苯胺类的毒性随ＰＨ的升高而增大,酚类的毒性随ＰＨ的升高而减小。     

环境胁迫和乙烯对番茄PR-NP24基因表达的影响

根据已报道的番茄PR-NP24基因序列设计引物,经PCR克隆出长为477bp的番茄PR-NP24基因片段,以该片段制备探针,采用Northern杂交技术对该基因在番茄(WT)和乙烯反应突变体番茄(Nr,rin,T4B-11)中的表达进行了研究.杂交结果表明,该基因主要在果实和根部表达,伤害抑制WT、Nr番茄叶片中该基因的表达,而对rin番茄叶片无明显影响;干旱、淹水等环境胁迫和乙烯均能不同程度地诱导其表达,而在不同温度下,PR-NP24基因表达变化不大.图7参13     

Intertemporal quota arbitrage in multispecies fisheries

In the management of natural resources, regulation often induces behavioral responses by resource users that ultimately undermine stated policy objectives. Examples of these unintended consequences have been associated with regulations ranging from the Endangered Species Act to laws governing clean air. In this paper we investigate an unintended behavioral response that can be triggered by conservation measures in multispecies fishery management, which leads to increased targeting of the species the conservation measures are meant to protect. Harvest is subject to stochastic variation, with output partially determined by the probability of encountering species of interest, either due to targeting or avoidance. Given the right conditions, an intertemporal arbitrage opportunity arises due to the fact that by targeting a stock in the current period, the probability of encountering that stock in the next period, when announced conservation measures are implemented, decreases. We present an empirical case study that supports the findings of the theoretical model. The results indicate that, by targeting so called weak stocks, some New England fishermen are willing to trade off increased costs today for increased expected profits in the future. To prevent the potentially harmful effects of this behavioral response, a manager may adopt precautionary provisions at the time a quota reduction is announced, or alternatively allow the industry to bank part of its current season's quota in order to alleviate the consequences of the reduction in the ensuing period. These results highlight the challenge of developing effective conservation strategies.     

空气质量监测运行方式分析

我国空气质量监督方式尚不统一,出现了三套数据的可比性问题。本文通过对这三种运行方式的经济技术特点分析,提出淘汰“五日法”、规范“24小时”法、发展自动连续监测和遥感监测的建议。     

Determination of C(5)-C(12) perfluoroalkyl carboxylic acids in river water samples in the Czech Republic by GC-MS after SPE preconcentration

A method employing solid phase extraction followed by gas chromatography-mass spectrometry with negative chemical ionization has been developed for determination of ultratrace concentrations of perfluoroalkyl carboxylic acids in river water. The effects of the experimental parameters, such as the pH, additions of NaCl and an ion-pairing agent (tetraethylammonium bromide) and the kind of the elution agent, on the efficiency of the test acid extraction have been studied. The analyte extraction recoveries and the limits of detection and determination have been found. The method developed has been tested on determinations of perfluoroalkyl carboxylic acids in the waters of the two largest Czech rivers, Vltava and Labe (Elbe). The best extraction results have been attained without any alteration of the sample pH, with an addition of tetrabutylammonium bromide (a concentration of 50 μg mL⁻¹ in the sample) and using methanol as the elution agent. Under these conditions, the recoveries of the test acids in the spiked real samples are within ranges from 60% to 104% and 53% to 111% for analyte concentration levels of 1.40 ng mL⁻¹ and 0.14 ng mL⁻¹, respectively, depending on the lengths of the perfluorinated chains of the acids. In general, the recovery decreases with increasing length of this chain. The method developed exhibits very low limits of detection and determination and the results are fully comparable with those obtained when using more expensive HPLC-MS/MS instrumentation. Typical values amount to tenths to tens of pg mL⁻¹ and units to one hundred pg mL⁻¹ for the limits of detection and determination, respectively; the measuring sensitivity increases with increasing length of the analyte chain. The analyzes of real samples from the Vltava and Elbe rivers have demonstrated that the results obtained are similar to the values published for contamination of the Elbe and other rivers in western and central Europe. The concentrations determined are of the order of units to tens of pg mL⁻¹ and the C₈-C₁₀ acids occur most often.     

Brassinosteroid alleviates phenanthrene and pyrene phytotoxicity by increasing detoxification activity and photosynthesis in tomato

The present study was carried out to investigate the effects of exogenously applied 24-epibrassinolide (BR) on growth, gas exchange, chlorophyll fluorescence characteristics, lipid peroxidation and antioxidant systems of tomato seedlings grown under different levels (0, 10, 30, 100 and 300 μM) of phenanthrene (PHE) and pyrene (PYR) in hydroponics. A concentration-dependent decrease in growth, photosynthetic pigment contents, net photosynthetic rate (Pn), stomatal conductance (Gs), maximal quantum yield of PSII (Fv/Fm), effective quantum yield of PSII (Φ_PSII), photochemical quenching coefficient (qP) has been observed following PHE and PYR exposure. By contrast, non-photochemical quenching coefficient (NPQ) was increased. PHE was found to induce higher stress than PYR. However, foliar or root application of BR (50 nM and 5 nM, respectively) alleviated all those depressions with a sharp improvement in the activity of photosynthetic machinery. The activities of guaicol peroxidase (GPOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as content of malondialdehyde (MDA) were increased in a dose-dependent manner under PHE or PYR treatments. Compared with control the highest increments of GPOD, CAT, APX, GR and MDA by PHE/PYR alone treatments were observed following 300 μM concentration, which were 67%, 87%, 53%, 95% and 74% by PHE and 42%, 53%, 30%, 86% and 62% by PYR, respectively. In addition, both reduced glutathione (GSH) and oxidized glutathione (GSSG) were induced by PHE or PYR. Interestingly, BR application in either form further increased enzymatic and non enzymatic antioxidants in tomato roots treated with PHE or PYR. Our results suggest that BR has an anti-stress effect on tomato seedlings contaminated with PHE or PYR and this effect is mainly attributed by increased detoxification activity.     

短期噪声暴露对作业人员心率的影响

综采工作面噪声污染严重,为了减少噪声污染对作业人员的身心健康和作业安全的不利影响,运用人因工程学、生理学、实验心理学和行为学的相关知识,利用24h动态心电图仪器进行试验研究,定量分析不同噪声水平和噪声暴露时间对作业人员心率的影响。结果表明:①噪声刺激会造成人心率升高;②噪声刺激水平和暴露时间大小都对被试者的心率产生了显著性影响;作业人员心率与噪声刺激的水平和暴露时间大小都有相关关系;③由于人耳对噪声的适应性,在同一噪声水平刺激下,随着暴露时间的延长,心率会有短暂恢复;④在噪声水平<95dB的噪声刺激下,随着暴露时间的增加,人对噪声的适应性比较明显,此时的噪声暴露时间是影响人心率的主导因素,且在噪声暴露40~50min时,由于人耳对噪声的适应性会出现短暂的心率恢复的现象,人体出现疲劳;⑤在噪声水平>95dB的噪声刺激下,随着暴露时间的增加,人对噪声无明显适应性,心率随着噪声分贝的增大在缓慢上升,此时的噪声水平是影响人的心率变化的主导因素。     

水利工程建设项目安全生产违规行为分析及监管模式优化

为优化水利工程建设项目安全监管模式、提高安全监管效能,选取山东省2020年重点水利工程质量安全监督报告进行统计分析,梳理出项目法人、代建单位、施工单位、监理单位、设计单位的安全生产违规行为共计1289个,以行为安全“2-4”模型为理论依据,对高频不安全行为产生的原因和规律进行研究。结果显示:水利工程建设项目五方参建单位的高频不安全行为中,安全管理体系程序文件不完善及执行过程不佳的组织不安全行为累计649频次,组织成员安全知识、意识、习惯不佳产生的个人不安全行为累计331频次。据此提出可将监管重点放在对参建单位管理体系的建立与运行上进行组织不安全行为控制,进而控制组织成员个人不安全行为,达到事故预防的目的。