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151.
Immigrant bacteria located on leaf surfaces are important to the health of plants as well as to people who consume fresh fruits and vegetables. However, the spatial distribution and organization of these immigrant bacteria on leaf surfaces are still poorly understood. To examine the spatial organization of these strains, two bacterial strains on tobacco leaves: (1) an indigenous strain, Pseudomonas stutzeri Nov. Y2011 labeled with green fluorescent protein, and (2) an immigrant strain Pantoea agglomerans labeled with cyan fluorescent protein isolated from pear, were studied. Under moist conditions, P. agglomerans cells quickly disappeared from direct observation by laser- scanning confocal microscopy, although elution results indicated that large amounts of live cells were still present on the leaves. Following exposure to desiccation stress, particles of cyan fluorescent protein-labeled P. agglomerans were visible within cracked aggregates of P. stutzeri Nov. Y2011. Detailed observation of sectioned aggregates showed that colonies of immigrant P. agglomerans were embedded within aggregates of P. stutzeri Nov. Y2011. Furthermore, carbon-resource partitioning studies suggested that these two species could coexist without significant nutritional competition. This is the first observation of an immigrant bacterium embedding within aggregates of indigenous bacteria on leaves to evade harsh conditions in the phyllosphere. 相似文献
152.
153.
日地环境对人类自发攻击性事件的影响 总被引:1,自引:0,他引:1
考察了日地空间物理环境扰动与人类自发攻击性群体性事件发生率之间相关性。统计分析发现,两者之间的相关程度很高,历元叠加后相关系数可达0.84和0.79、这表明日地空间物理环境对人类攻击性本能和情绪具有显著的调节作用,导致全球自发攻击性群体事件年发生率具有11a准周期波动特征。其作用机制可能是地磁场活动和大气温度的影响。 相似文献
154.
1991/1992年是厄尔尼诺年,也是全球自然灾害频发、重灾事件突出的异常年份。本文对发生在1991/1992年厄尔尼诺事件期间的全球主要气象灾害进行简介和评述。 相似文献
155.
应用人工神经网络方法对海水入侵危害程度划区分类 总被引:5,自引:0,他引:5
本文将目前信息处理系统中最有效的人工神经网络方法,应用于海水入侵地区,对其危害程度进行划区分类,提出了解题原理,步骤和计算方法,丰富了对海水入侵现象的研究手段。在莱州市滨海地区的计算表明,该方法是可行的。 相似文献
156.
Long- and short-chain AHLs affect AOA and AOB microbial community composition and ammonia oxidation rate in activated sludge 总被引:1,自引:0,他引:1
Jie Gao Yu Duan Ying Liu Xuliang Zhuang Yichen Liu Zhihui Bai Wenlin M Guoqiang Zhuang 《环境科学学报(英文版)》2019,31(4):53-62
Quorum sensing (QS) regulation of the composition of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) communities and functions in wastewater treatment was investigated. Specifically, we explored the role of N-acyl-l-homoserine lactones (AHLs) in microbial community dynamics in activated sludge. On average, the specific ammonia-oxidising-rate increased from 1.6 to 2.8?mg?NH4+-N/g?MLSS/hr after treatment with long-chain AHLs for 16?days, and the addition of AHLs to sludge resulted in an increased number of AOA/AOB amoA genes. Significant differences were observed in the AOA communities of control and AHL-treated cultures, but not the AOB community. Furthermore, the dominant functional AOA strains of the Crenarchaeota altered their ecological niche in response to AHL addition. These results provide evidence that AHLs play an important role in mediating AOA/AOB microbial community parameters and demonstrate the potential for application of QS to the regulation of nitrogen compound metabolism in wastewater treatment. 相似文献
157.
Shuang Hou Yingying Zhuang Yayun Deng 《Journal of environmental science and health. Part. B》2017,52(8):525-537
Cycloxaprid (CYC) is a new cis-configuration neonicotinoid insecticide, which is currently under development in China for agricultural pest control. Considering the photodegradation of CYC is important for the application of CYC in the future, the photochemical behavior of CYC in aqueous solution was herein investigated in a “merry-go-round” reactor under a 300 W high-pressure mercury lamp. Twenty-five photodegradation products were identified via UPLC-TOF-ESI-MS/MS. The results suggested that NTN32692, the precursor of CYC was the predominant photodegradation product. CYC photodegrades via a more complex mechanism than imidacloprid and four potential photodegradation pathways were proposed. 相似文献
158.
159.
秸杆燃烧中OCS的排放因子和排放估算 总被引:2,自引:0,他引:2
建立了痕量羰基硫采样及分析方法。利用低温预捕集和被捕集样直接释放进入分离柱技术,对压缩空气进行采样测定。得出了压缩空气中OCS约在2.94×10^-3μg/L,方法精确度以标准误差系数计为±0.72%,利用此采样及分析方法对实验室规模的生物质封闭燃烧系统,稻草、玉米秸、科杆燃烧中排痕量OCS进行了采样分析,得出稻草、玉米秸麦杆燃烧排气中OCS的排放量,以排放因子表示分别是:1.80g/t,2.75 相似文献
160.
首次用x-5树脂吸附三丁基锡(TBT)化合物。结果表明,X-5树脂吸附TBT化合物具有吸附容量大、吸附速度快等优点,符合Freundlich吸附等温式;用自制的吸附注(长度为11cm,内径为0.55cm的玻璃管,内装x-5大孔网状树脂,约0.7g)作TBT吸附剂,研究各种因素对吸附及脱附效率的影响。结果表明,吸附率主要取决于柱长及流速,而溶液的盐度及pH值影响不大;脱附率主要取决于洗脱剂的流速,而pH值影响不大;实际样品的回收率超过90%。 相似文献