Plant phenology, growth and nutritive quality of Briza maxima: responses induced by enhanced ozone atmospheric levels and nitrogen enrichment

An assessment of the effects of tropospheric ozone (O₃) levels and substrate nitrogen (N) supplementation, singly and in combination, on phenology, growth and nutritive quality of Briza maxima was carried out. Two serial experiments were developed in Open-Top Chambers (OTC) using three O₃ and three N levels. Increased O₃ exposure did not affect the biomass-related parameters, but enhanced senescence, increased fiber foliar content (especially lignin concentration) and reduced plant life span; these effects were related to senescence acceleration induced by the pollutant. Added N increased plant biomass production and improved nutritive quality by decreasing foliar fiber concentration. Interestingly, the effects of N supplementation depended on meteorological conditions and plant physiological activity. N supplementation counteracted the O₃-induced senescence but did not modifiy the effects on nutritive quality. Nutritive quality and phenology should be considered in new definitions of the O₃ limits for the protection of herbaceous vegetation.     

Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O₃) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O₃ fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O₃ fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O₃, determined from the mRNA levels of the major allergens. We conclude that O₃ can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase.     

基于H∞理论的磁流变阻尼器半主动容错控制

建筑结构的半主动控制系统中的传感器,在强震作用下可能因出现故障而影响控制效果。以磁流变阻尼器为例,研究半主动容错控制系统的设计方法。首先,研究了基于状态观测器的半主动H∞控制器设计方法,并将之应用到建筑结构采用磁流变阻尼器的减振控制中;运用改进Bouc-Wen模型,计算磁流变阻尼器的阻尼力,通过求解一个代数Riccati方程和一个状态观测方程,得出了基于状态观测器的H∞主动控制律;再对其采用Clipped-optimal方法实施半主动控制策略。然后,针对传感器故障,利用观测器组的输出残差对故障进行在线诊断,并通过几个观测器状态值的比较得到故障的大小,并据此对传感器的测量值进行修正,从而消除故障对闭环系统的影响,最终实现半主动H∞容错控制。仿真结果表明,该方法具有很好的容错控制效果。     

Degradation of 17α-ethinylestradiol by ozonation--identification of the by-products and assessment of their estrogenicity and toxicity

The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in waters at low levels is a concern due to its ability to act as an endocrine disruptor. Ozone (O₃) is commonly used in water treatment and reacts with EE2 to form by-products having characteristics that are mostly unknown. The aim of this study was to identify the by-products of E2 and EE2 ozonation and determine their estrogenicity and toxicity relative to the parent compound. Ozonation by-products were identified via LC-MS analysis. The estrogenicity was measured using the YES assay, and toxicity was determined by monitoring effects on histology of fetal rat testes and testosterone secretion by these tissues. Two EE2 by-products were identified with open phenolic ring structures (masses 302 and 344 u). The Yeast Estrogen Screening (YES) assay showed a decreased but incomplete removal of estrogenicity after ozonation of EE2. Histological analysis of fetal testes revealed that neither E2 nor EE2, with or without ozonation, had any effect on seminiferous cord formation; however, a remarkable negative effect on testosterone secretion was observed, with EE2 by-products after ozonation showing the most rapid and extensive inhibition. These results show that the removal of EE2 via reaction with O₃ resulted in the formation of by-products that are less estrogenic (as demonstrated by the YES assay), but have a greater negative impact on testosterone secretion. Thus, the disappearance of the parent compound is not a sufficient endpoint, as the by-products created may be more toxic. Care should be taken when implementing oxidation applications such as ozone during waste water treatment.     

Studies on the residues of phosalone on chilli by GLC after multiband plate cleanup

Abstract

Four sprays of 0.05 ana 0.10% phosalone were given on chilli (Capsicum annuum Linn.) crop at an interval of 15 days starting from 21 days after transplanting. Residues were determined in the green chilli fruits by GLC after cleanup of extract on multiband thin‐layer plate. The half‐lives of residues were 1.55 and 1.68 days on chilli fruits from the crop treated with four sprays of 0.05 and 0.10% phosalone respectively. The time required to reach the tolerance limit of 1 ppm after last spray with 0.05 and 0.10 % emulsion was 4.75 and 7.62 days respectively. Washing of fruits under tap water was found effective in bringing down the level of phosalone residues by 21.64 to 75.11 %.     

“Perceived neighbourhood” and tolerance relations: the case of Arabs and Jews in Jaffa,Israel

This paper examines the complex social reality of mixed ethnic residential areas, as reflected in drawn perceived neighbourhoods of Jews and Arabs living in homogenous and mixed neighbourhoods in Jaffa, Tel Aviv. Through in-depth interviews conducted among 89 Jaffa's residents, it illustrates how different perceptions about the residential area and its residents (including attitudes, emotions, feeling of fear/safety, collective identity and tolerant relations) are reflected in the form, size and consensus area of residents' perceived neighbourhoods. The study finds a clear association between tolerant attitudes and the size and consensus area of the perceived neighbourhoods. Arabs perceive their neighbourhood as significantly larger than Jews do and are characterised by a larger consensus area. These findings are explained by the Arab's strong social cohesion, common national identity, rootedness in Jaffa, as well as by tolerant attitudes towards Jaffa's Jewish population. The study demonstrates the interrelation between the spatial, social and perceptual dimensions associated with the mixed residential area, and illustrates how these dimensions are reflected in drawn perceived neighbourhoods.     

不适宜生长条件对混菌降解苯胺的影响

分别从台州和衢州某化工厂的好氧池中分离筛选得到2株苯胺降解菌TZ1和JH1,经16S rDNA测序鉴定为Comamonas sp.TZ1和Pseudomonas sp.JH1,均具有较强的苯胺降解能力,培养24 h后,可使初始浓度为800 mg/L的苯胺去除率达到96.4%~98.4%。在此基础上,按体积比1∶1将2株菌液进行混合构建了混合菌体系,进而对比考察了苯胺初始浓度、pH、盐度和重金属等环境因子对单一菌和混合菌生长量及降解苯胺效果的影响,重点探讨混合菌对不适宜生长环境的适应性及其对苯胺的降解特性。通过单一菌和混合菌对比实验发现,在适宜苯胺初始浓度、pH和盐度条件下,混合菌的生长量略高于单一菌;在不适宜生长的高浓度苯胺、pH和盐度条件下,混合菌也表现出了更强的适应性和苯胺矿化能力。Zn2+和Cr6+耐受实验则表明,对于Cr6+,混合菌表现出了更强的耐受能力,而对于Zn2+并没有表现出更强的耐受能力。     

好氧颗粒污泥耐受PFOS的结构稳定性及微生物响应

以好氧颗粒污泥为接种污泥,通过全氟辛烷磺酸(PFOS)长期驯化实现耐PFOS颗粒的培养,考察不同驯化时期的污泥基本特性,并结合微生物群落演替过程、微生物表型分布以及功能途径的变化情况,以揭示其耐受机制.结果表明,好氧颗粒污泥经历解体、再形成和成熟3个阶段后可在PFOS暴露下稳定维持.驯化成熟后的好氧颗粒污泥表面丝状菌减少,并且被大量胞外聚合物(EPS)所包裹,结构更加致密.驯化期间颗粒污泥中存在大量抗性细菌以及维持颗粒稳定相关细菌,主要包括unclassified＿f＿＿Comamonadaceae、Defluviicoccus、Dongia、Rhodoplanes、Flavobacterium、Thauera、Azospira、Candidatus＿Competibacter、Azoarcus和norank＿f＿＿A4b,且部分菌属间存在显著的正相关性.群体感应途径和细菌趋化途径相关基因丰度在解体期上调,在颗粒形成和成熟期恢复至初始水平,说明细菌的群体感应效应和趋化性能够在颗粒应激过程中起重要作用.因此,好氧颗粒污泥可以通过特定菌群积极响应、促进细菌趋化作用和群体感应作用、提高EPS...     

Elevated ozone affects the genetic composition of Plantago lanceolata L. populations

The genetic composition and diversity of Plantago lanceolata L. populations were analysed using amplified fragment length polymorphism (AFLP) as well as simple sequence repeat (SSR) markers to test for differences in an old semi-natural grassland after five years of treatment with ambient or elevated ozone (O3) using a free-air fumigation system. Genetic diversity in populations exposed to elevated O3 was slightly higher than in populations sampled from control plots. This effect was significant for AFLP-based measures of diversity and for SSR markers based on observed heterozygosity. Also, a small but significant difference in genetic composition between O3 treatments was detected by analysis of molecular variance and redundancy analysis. The results show that micro-evolutionary processes could take place in response to long-term elevated O3 exposure in highly diverse populations of outbreeding plant species.     

Suitability of Nicotiana tabacum 'Bel W3' for biomonitoring ozone in São Paulo, Brazil

Nicotiana tabacum 'Bel W3' is a widely used sensitive bioindicator for ambient ozone, but it is rarely used in tropical countries. Our goal was to determine the suitability of this plant for biomonitoring ozone in the city of S?o Paulo by evaluating the relationships between leaf necroses and ozone under field conditions and measurements of chlorophyll a fluorescence and antioxidants in plants exposed to different concentrations of ozone in closed chambers. While a weak linear relationship between leaf injury and ozone concentrations (R(2)=0.10) was determined in the field, a strong linear relationship was observed in the chamber experiments. Maximum leaf injury was observed in plants submitted to 40 ppb, which coincided with a significant decrease in fluorescence and total ascorbic acid. The relationship between leaf damage observed in the field and ozone was improved when the concentrations were limited to 40 ppb (R(2)=0.28).