10 research outputs found

    GENETIC DIVERSITY OF MANGROVE PLANT- Avicennia marina ALONG BEIHAI COAST BY RAPD

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    采用随机扩增多态 DNA(RAPD)分析了分布于广西北海海岸的 3个自然分布居群的白骨壤群落 ,用 15个随机引物进行 PCR扩增 ,3个居群的 RAPD多态位点的百分率分别为英罗湾 38.35 % ,大冠沙 35 .2 1%钦州湾2 9.41%。 3个居群内的平均遗传距离分别为 0 .10 8、0 .147和 0 .16 5 ;3个居群两两之间的平均遗传距离分别为大冠沙 -英罗湾 0 .135、大冠沙 -钦州湾 0 .16 3和英罗湾 -钦州湾 0 .179。结果表明 ,白骨壤居群内和居群间的遗传变异较低。Random amplified polymorphic DNA(RAPD)technique was applied to analyzing population genetics of native Avicennia marina,an wide spread species,whose natured population today is destroyed by mankind along Baihai,Guangxi coast.Leaf samples were collected form 30 natural trees in the native population and 15 arbitrary primers were used to amplify 73,71 and 68 bands that contain 28,25 and 20 polymorphic RAPD loci in three populations respectively.The mean genetic distance intra-populations were 0.165 、0.147 and 0.108;while inter-population were 0.135、0.163 and 0.179.The results showing that either the intra-or inter-population genetic variety were low.国家教育部博士点基金项目资

    Controlling Reversible Expansion of Li2O2 Formation and Decomposition by Modifying Electrolyte in Li-O2 Batteries

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    锂空电池分别使用空气中的氧气和金属锂作为正负极活性材料,具有极高的能量密度。但是,这一体系尚不能实现商业化的应用,其中一些关键问题未能解决。由于其正极活性材料是气体,使得电化学反应涉及气-液-固三相界面,电极过程十分复杂。与其它二次电池相比,空气电极需要考虑结构因素和催化因素。不仅要改善氧气电化学反应的动力学迟缓问题,还要考虑放电产物的驻留空间问题。董全峰教授课题组在前期开展了基于空气电极固相表面电催化研究,并结合电极结构方面的问题,构筑了有利于氧气发生反应的仿生开放式结构电极。 该研究工作主要由化学化工学院2015级iChEM直博生林晓东(第一作者)在董全峰教授、郑明森副教授和龚磊副教授的共同指导下完成,理论计算由袁汝明助理教授(共同第一作者)完成,曹勇、丁晓兵、蔡森荣、韩博闻等学生参与了部分工作。周志有教授和洪宇浩博士生在电化学微分质谱方面给予大力的帮助与支持。【Abstract】The aprotic lithium-oxygen (Li-O2) battery has attracted worldwide attention because of its ultrahigh theoretical energy density. However, its practical application is critically hindered by cathode passivation, large polarization, and severe parasitic reactions. Here, we demonstrate an originally designed Ru(Ⅱ) polypyridyl complex (RuPC) though which the reversible expansion of Li2O2 formation and decomposition can be achieved in Li-O2 batteries. Experimental and theoretical results revealed that the RuPC can not only expand the formation of Li2O2 in electrolyte but also suppress the reactivity of LiO2 intermediate during discharge, thus alleviating the cathode passivation and parasitic reactions significantly. In addition, an initial delithiation pathway can be achieved when charging in turn; thus, the Li2O2 products can be decomposed reversibly with a low overpotential. Consequently, the RuPC-catalyzed Li-O2 batteries exhibited a high discharge capacity, a low charge overpotential, and an ultralong cycle life. This work provides an alternative way of designing the soluble organic catalysts for metal-O2 batteries.This work was supported by the National 973 Program (2015CB251102), the Key Project of National Natural Science Foundation of China (21673196, 21621091, 21703186, 21773192),and the Fundamental Research Funds for the Central Universities (20720150042,20720150043). The authors thank Prof. Eric Meggers at Philipps-Univeristaet Marburg for his discussion about the synthesis of RuPC complex; Prof. Gang Fu at Xiamen University for his instructive discussions in DFT calculations; Lajia Yu and Dandan Tao at Xiamen University for their assistance in EPR experiments and UV-Vis spectroscopy experiments, respectively; and Yu Gu and Tao Wang at Xiamen University for their discussions in XPS results and CV data,respectively. 该工作得到科技部重大基础研究计划(项目批准号:2015CB251102)、国家自然科学基金(项目批准号:21673196、21621091、21703186、21773192)和中央高校基本科研业务费专项资金(项目批准号:20720150042、20720150043)的资助。 此外,感谢傅钢教授在理论计算方面的讨论和建议,Eric Meggers教授在配合物合成上的讨论,泉州师范学院吴启辉教授和化学化工学院谷宇博士生在X射线光电子能谱方面的帮助,于腊佳老师在电子顺磁共振实验上的帮助,陶丹丹博士生在紫外可见光谱测试上的帮助以及王韬博士生在循环伏安方面的讨论

    不久的将来气候会变冷吗?

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    近期新疆东天山冰川退缩及其对水资源影响

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    4~2 ka BP中国干旱的证据和模拟研究

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    近千年中国温度序列的建立

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    结合HJ1A/B卫星数据和生态因子的籽粒品质监测/Monitoring wheat quality based on HJ1A/B remote sensing data and ecological factors[J]

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    该研究引入温度、降水、太阳辐射和土壤肥力等影响小麦籽粒蛋白质含量的重要生态子,结合感数据进行小麦籽粒蛋白质含量监测.以北京郊区的小麦种植区为实验区,获取多时相的HJ1A/B卫星数据,多个气象站点全生育期气象数据和土壤养分数据,以及收获时小麦籽粒蛋白质含量.分别构建了感光谱蛋白质含量模型、生态子籽粒蛋白质含量模型、光谱生态子蛋白质含量模型.结果表明:北京地区冬小麦以5月11日(开花期左右)NDVIgreen 值与籽粒蛋白质含量相关性最好,达到极显著水平,此该时期为冬小麦籽粒蛋白质含量感监测的最佳时相,并将利用该时期的NDVIgreen参与光谱蛋白质含量模型、光谱生态子蛋白质含量模型的构建.对光谱蛋白质含量模型、生态子籽粒蛋白质含量模型、光谱生态子蛋白质含量模型进行F检验,表明各模型均达到极显著水平,3种模型的决定系数分别为:0.782,0.635,0.843,相对误差分别为:0.151,0.123,0.049.说明综合利用感数据和生态子的监测结果比单独利用感数据或单独利用生态子的精度高.引入生态子的小麦籽粒蛋白质含量感监测有助提高监测精度,并增加监测模型的农业机理
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