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High pressure responsive luminescence of flexible Eu^(3+) doped PVDF fibrous mats

Journal of Materials Science & Technology 2021年第7期66卷 103-111页

作者： Carlos Hernandez San tosh K.Gupta Jose P.Zuniga Jorge Vidal Rene Galvan hector guzman Lilian Chavez Karen Lozano Yuanbing Mao Department Department of Chemistry University of Texas Rio Grande Valley1201 West University DriveEdinburgTX 78539USA Radiochemistry Division Bhabha Atomic Research CentreTrombayMumbai400085USA Department of Electrical Engineering University of Texas Rio Grande ValleyEdinburgTX 78539USA Department of Chemistry Illinois Institute of Technology3105 South Dearborn StreetChicagoIL 60616USA

Exploring lanthanide doped materials and their high-pressure optical properties is important from the perspective of designing pressure sensors, piezoelectric materials, scintillators, and optoelectronic devices, just to mention a few. Understanding the high-pressure optical properties of polymeric fibrous mats provides significant advantages in terms of flexibility, tunability, facile processability, and malleability. In this work, we have developed flexible polyvinylidene difluoride(PVDF) fibrous mats doped with an Eu^(3+) source of Eu(NO_(3))_(3)·5H_(2)O(EN-PF) or Eu_(2)(SO_(4))_(3)(ES-PF) by a Forcespinning■ method. Microstructural analysis of these two systems indicates that Eu(NO_(3))_(3)·5H_(2)O and Eu_(2)(SO_(4))_(3) are homogeneously distributed and dispersed into the PVDF matrix. Fiber formation promotes a β-phase PVDF. Eu^(3+) doping increases the β-phase. Its fraction is larger for the ES-PF mats. To understand their high-pressure optical properties, their photoluminescence spectra have been taken at various pressures up to 58 GPa in a diamond anvil cell. High-pressure luminescence illustrates a clear change in asymmetry ratio, peak intensity, peak breadth, color coordinate, and color temperature of Eu^(3+) ions from both EN-PF and ES-PF with a different extent of changes. Specifically, Eu^(3+) ions in the ES-PF mats switch from asymmetric to symmetric environment as pressure increases. Those in the EN-PF mats present symmetric environment for all tested pressures. Both of the Eu^(3+) doped PVDF systems present irreversible changes. Therefore,the EN-PF fibrous mats present an opportunity to make pressure induced red-orange-yellow tunable phosphors for multifunctional applications.

关键词： Polyvinylidene difluoride Europium Fiber High pressure Luminescence

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开凿巴拿马运河后珊瑚礁生长的历史性衰退

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AMBIO－人类环境杂志 2008年第5期37卷 325-329页

作者： hector M．guzman Roberto Cipriani Jeremy B．C．Jackson 田洪军（译）林宝法（校）史密森热带研究所委内瑞拉西蒙玻利瓦尔大学斯克里普斯海洋学研究所地学研究部不详

巴拿马运河接近其船只的大小和吨位的处理能力,巴拿马人已决定将它扩大。运河的扩大可能要考虑对海洋沿海生物栖息地的历史性的长期持久影响,特别是对敏感的珊瑚礁。就像对其他同等重要的问题一样,这些潜在影响在全国公民投票期间进行... 详细信息

巴拿马运河接近其船只的大小和吨位的处理能力,巴拿马人已决定将它扩大。运河的扩大可能要考虑对海洋沿海生物栖息地的历史性的长期持久影响,特别是对敏感的珊瑚礁。就像对其他同等重要的问题一样,这些潜在影响在全国公民投票期间进行了讨论,例如其对森林、流域和供水系统的影响。珊瑚的增长率为珊瑚状况和过去的环境条件提供一个直接的衡量尺度,这类似于年轮分析。我们在一个世纪长的(1880～1989年)年代表上研究稳定同位素、金属地球化学示踪、和增长率,此年代表是基于对主要的造礁珊瑚铁星珊瑚(Siderastrea siderea)的77个岩芯分析制成,这些岩芯是在加勒比海的运河入口处附近收集的。我们的结果表明,珊瑚生长的逐渐衰退与海水表层温度的变化无关,但与巴拿马运河的开凿和通航所导致的沿海地区的径流和泥沙淤积有关。

关键词：巴拿马运河珊瑚生长珊瑚礁历史性衰退开凿地球化学示踪岩芯分析

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Species diversity of thrips (Thysanoptera) in selected avocado orchards from Mexico based on morphology and molecular data

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Journal of Integrative Agriculture 2018年第11期17卷 2509-2517页

作者： Daniel Bravo-Perez Ma. Teresa Santillbn-Galicia Roberto M. Johansen-Naime hector Gonzalez-Hernandez Obdulia L. Segura-Leon Daniel L, Ochoa-Martinez Stephanie guzman-Valencia Posgrado en Fitosanidad-Entomologia y Acarologia Colegio de Postgraduados Km 36.5 Carretera Mexico-Texcoco Montecillo Texcoco Estado de Mexico 56230 Mexico Instituto de Biologia de la Universidad Nacional Autonoma de Mexico (IBUNAM) Circuito exterior s/n Ciudad Universitaria Coyoacan Ciudad de Mexico 04510 Mexico Posgrado en Fitosanidad-Fitopatologia Colegio de Postgraduados Km 36.5 Carretera Mexico-Texcoco Montecillo Texcoco Estado de Mexico 56230 Mexico

Avocado is one of the most important crops in the world, and Mexico is the largest producer of this fruit. Several insect pests affect its production, and thrips are amongst the most important. A key step in the design of control methods is accurate species identification. Despite this, formal reports on species diversity of thrips in Mexico are very scarce. Morphological identification can sometimes be time-consuming and inconclusive. Therefore, we explored the species diversity of thrips in Mexican avocado orchards （Michoacan state） based on partial sequences of the mitochondrial gene cytochrome oxidase subunit I （COl）. Forty-four specimens were analysed, which represented approximately 8% of all individuals collected from five localities distributed in three Municipalities. All specimens were analysed using the COl marker, and specimens within the genera Frankliniella were also analysed using a marker within the D2 domain of the 28S （28SD2） nuclear ribosomal DNA. Molecular identifications were confirmed using morphological taxonomy. Overall, six genera were found （Neohydatothrips, Scirtothrips, Frankliniella, Arorathrips, Caliothrips and Leptothrips）. AII genera contained only one species, except Frankliniella, for which there were six species. Data from the two molecular markers suggest the existence of cryptic species within Mexican F. occidentalis populations.

关键词： molecular taxonomy morphological identification cytochrome oxidase subunit I 28S nuclear ribosomal DNA.

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