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Sample records for eu energy reform

  1. A System of Systems Approach to the EU Energy System

    NASA Astrophysics Data System (ADS)

    Jess, Tom; Madani, Kaveh; Mahlooji, Maral; Ristic, Bora

    2016-04-01

    Around the world, measures to prevent dangerous climate change are being adopted and may change energy systems fundamentally. The European Union (EU) is committed to reducing greenhouse gas emission by 20% by 2020 and by 80-95% by 2050. In order to achieve this, EU member states aim to increase the share of renewables in the energy mix to 20% by 2020. This commitment comes as part of a series of other aims, principles, and policies to reform the EU's energy system. Cost-efficiency in the emissions reductions measures as well as strategic goals under the Resource Efficient Europe flagship initiative which would include a more prudent approach to other natural resources such as water and land. Using the "System of Systems Approach", as from Hadian and Madani (2015), energy sources' Relative Aggregate Footprints (RAF) in the EU are evaluated. RAF aggregates across four criteria: carbon footprint, water footprint, land footprint, and economic cost. The four criteria are weighted by resource availability across the EU and for each Member State. This provides an evaluation of the overall resource use efficiency of the EU's energy portfolio and gives insight into the differences in the desirability of energy sources across Member States. Broadly, nuclear, onshore wind, and geothermal are most desirable under equal criteria weights and EU average weighting introduces only small changes in the relative performance of only few technologies. The member state specific weightings show that most countries have similar energy technology preferences. However, the UK deviates most strongly from the average, with an even stronger preference for nuclear and coal. Sweden, Malta and Finland also deviate from the typical preferences indicating the complexity in play in reforming the EU energy system. Reference Hadian S, Madani K (2015) A System of Systems Approach to Energy Sustainability Assessment: Are All Renewables Really Green? Ecological Indicators, 52, 194-206.

  2. Reforming the EU Clinical Trials Directive: streamlining processes or a radical "new" agenda?.

    PubMed

    McHale, Jean V

    2013-09-01

    From its conception the EU Clinical Trials Directive met with controversy. Some saw it as an unnecessary inhibitor to scientific research, introducing bureaucracy which was unduly expensive, slowing down the clinical trial approval system. The Directive however also enshrined respect for fundamental rights in relation to clinical trials decision-making and impacted upon the domestic law of member states facilitating the alignment of trial review processes. Nearly a decade after its implementation the EU is moving towards implementation of further reform in this area, from a Directive to a Regulation, from a system placing the research ethics system at the heart of the clinical trials approval committee to one which does not and which represents a see change in international and domestic approaches to research ethics. This article critically examines the proposed reform of the regulation of clinical trials on medicinal product through the introduction of a new EU Regulation and asks whether this can be seen as a natural streamlining of processes or a radical new agenda in EU health law and regulation. PMID:23977734

  3. Integrated solar reforming for thermochemical energy transport

    NASA Astrophysics Data System (ADS)

    Rozenman, T.

    1987-12-01

    This report presents a design study of two reforming processes as applied to the concept of solar thermochemical energy transport. Conceptual designs were carried out for steam-methane and CO2-methane reforming plants. A solar central receiver reformer was designed as an integrated reactor with the chemical reaction tubes placed inside the receiver cavity. The two plant designs were compared for their energy efficiency and capital cost. The CO2 reforming plant design results in higher energy efficiency but requires a catalyst which is still in an experimental stage of development. A third design was performed as a modification of the steam reforming plant utilizing a Direct Contact system, in which the process steam is generated by utilizing the heat of condensation. This system resulted in the highest energy efficiency. A comparison of the capital cost of these three plant designs shows them to be equivalent within the estimation accuracy of 25 percent.

  4. Definition of an intramolecular Eu-to-Eu energy transfer within a discrete [Eu2L] complex in solution.

    PubMed

    Nonat, Aline; Regueiro-Figueroa, Martín; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos; Charbonnière, Loïc J

    2012-06-25

    Ligand L, based on two do3a moieties linked by the methylene groups of 6,6'-dimethyl-2,2'-bipyridine, was synthesized and characterized. The addition of Ln salts to an aqueous solution of L (0.01 M Tris-HCl, pH 7.4) led to the successive formation of [LnL] and [Ln(2)L] complexes, as evidenced by UV/Vis and fluorescence titration experiments. Homodinuclear [Ln(2)L] complexes (Ln = Eu, Gd, Tb, Yb, and Lu) were prepared and characterized. The (1)H and (13)C NMR spectra of the Lu and Yb complexes in D(2)O solution (pD = 7.0) showed C(1) symmetry of these species in solution, pointing to two different chemical environments for the two lanthanide cations. The analysis of the chemical shifts of the Yb complex indicated that the two coordination sites present square antiprismatic (SAP) coordination environments around the metal ions. The spectroscopic properties of the [Tb(2)L] complex upon ligand excitation revealed conventional behavior with τ(H2O) = 2.05(1) ms and ϕ(H2O) = 51%, except for the calculation of the hydration number obtained from the luminescent lifetimes in H(2)O and D(2)O, which pointed to a non-integer value of 0.6 water molecules per Tb(III) ion. In contrast, the Eu complex revealed surprising features such as: 1) the presence of two and up to five components in the (5)D(0)→(7)F(0) and (5)D(0)→(7)F(1) emission bands, respectively; 2) marked differences between the normalized spectra obtained in H(2)O and D(2)O solutions; and 3) unconventional temporal evolution of the luminescence intensity at certain wavelengths, the intensity profile first displaying a rising step before the occurrence of the expected decay. Additional spectroscopic experiments performed on [Gd(2-x)Eu(x)L] complexes (x = 0.1 and 1.9) confirmed the presence of two distinct Eu sites with hydration numbers of 0 (site I) and 2 (site II), and showed that the unconventional temporal evolution of the emission intensity is the result of an unprecedented intramolecular Eu-to-Eu

  5. Ping Pong: Competing Leadership for Reform in EU Higher Education 1998-2006

    ERIC Educational Resources Information Center

    Corbett, Anne

    2011-01-01

    How effective is EU cooperation in higher education? This article treats the issue as one of effectiveness in policy-making. What are the policy ideas which the EU wishes to feed into a policy domain where it has to operate largely through political cooperation and a modest degree of incentive funding? What outcomes are possible? The question is…

  6. Eu2+-->Mn2+ energy transfer in NaCl

    NASA Astrophysics Data System (ADS)

    Rubio O., J.; Murrieta S., H.; Powell, R. C.; Sibley, W. A.

    1985-01-01

    Crystals of NaCl containing different concentrations of Eu2+ and Mn2+ ions (the Eu concentration always being less than that of Mn) were investigated by optical and EPR spectroscopy. The results show that Eu2+-Mn2+ pairs form preferentially in this material and that highly efficient energy transfer occurs from the Eu2+ ions to the near-neighbor Mn2+ ions. Over 99% of the Eu2+ ions are paired, and these pairs are not significantly affected by the state of aggregation of the Mn ions, although in the various samples evidence for manganese ions in their dipolar state, as well as precipitated into the Suzuki phase, exists. The excitation spectra of the orange manganese emission show, in addition to the Eu2+ 4f7-->4f65d transitions, Mn2+ transitions associated with the Suzuki phase and with Mn2+-cation vacancy dipoles. The peak positions of these Mn2+-crystal-field-sensitive transitions were fitted theoretically with expressions including Racah-Tress and seniority corrections. This procedure allowed the determination of the relevant crystal-field parameters.

  7. Study of energy transfer mechanism from ZnO nanocrystals to Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Mangalam, Vivek; Pita, Kantisara; Couteau, Christophe

    2016-02-01

    In this work, we investigate the efficient energy transfer occurring between ZnO nanocrystals (ZnO-nc) and europium (Eu3+) ions embedded in a SiO2 matrix prepared using the sol-gel technique. We show that a strong red emission was observed at 614 nm when the ZnO-nc were excited using a continuous optical excitation at 325 nm. This emission is due to the radiative 5D0 → 7F2 de-excitation of the Eu3+ ions and has been conclusively shown to be due to the energy transfer from the excited ZnO-nc to the Eu3+ ions. The photoluminescence excitation spectra are also examined in this work to confirm the energy transfer from ZnO-nc to the Eu3+ ions. Furthermore, we study various de-excitation processes from the excited ZnO-nc and their contribution to the energy transfer to Eu3+ ions. We also report the optimum fabrication process for maximum red emission at 614 nm from the samples where we show a strong dependence on the annealing temperature and the Eu3+ concentration in the sample. The maximum red emission is observed with 12 mol% Eu3+ annealed at 450 °C. This work provides a better understanding of the energy transfer mechanism from ZnO-nc to Eu3+ ions and is important for applications in photonics, especially for light emitting devices.

  8. Energy and exergy analysis of an ethanol reforming process for solid oxide fuel cell applications.

    PubMed

    Tippawan, Phanicha; Arpornwichanop, Amornchai

    2014-04-01

    The fuel processor in which hydrogen is produced from fuels is an important unit in a fuel cell system. The aim of this study is to apply a thermodynamic concept to identify a suitable reforming process for an ethanol-fueled solid oxide fuel cell (SOFC). Three different reforming technologies, i.e., steam reforming, partial oxidation and autothermal reforming, are considered. The first and second laws of thermodynamics are employed to determine an energy demand and to describe how efficiently the energy is supplied to the reforming process. Effect of key operating parameters on the distribution of reforming products, such as H2, CO, CO2 and CH4, and the possibility of carbon formation in different ethanol reformings are examined as a function of steam-to-ethanol ratio, oxygen-to-ethanol ratio and temperatures at atmospheric pressure. Energy and exergy analysis are performed to identify the best ethanol reforming process for SOFC applications. PMID:24561628

  9. Photoluminescence and energy transfer process in Gd2O3:Eu3+, Tb3+

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, T.; Bose, A. Chandra

    2016-05-01

    Variation in photoluminescence (PL) properties of Eu3+ and Tb3+ as a function of co-dopant (Tb3+) concentration are studied for Gd2-x-yO3: Eu3+x Tb3+y (x = 0.02, y = 0.01, 0.03, 0.05). The crystal structure analysis is carried out by X-ray Diffraction (XRD). Absence of addition peaks corresponding europium or terbium phase confirms the phase purity. Diffuse reflectance spectroscopy (DRS) reveals the absorption peaks corresponding to host matrix, Eu3+ and Tb3+. The bandgap calculated from Kubelka - Munk function is also reported. PL spectra are recorded at the excitation wavelength of 307 nm and the emission peak corresponding to Eu3+ confirms the energy transfer from Tb3+ to Eu3+. The agglomeration of particles acts as quenching centres for energy transfer at higher concentrations.

  10. The influence of triplet energy levels of bridging ligands on energy transfer processes in Ir(III)/Eu(III) dyads.

    PubMed

    Jiang, Weili; Lou, Bin; Wang, Jianqiang; Lv, Hongbin; Bian, Zuqiang; Huang, Chunhui

    2011-11-21

    A series of N^N,O^O-bridging ligands based on substituted 1-(pyridin-2-yl)-3-methyl-5-pyrazolone and their corresponding heteroleptic iridium(III) complexes as well as Ir-Eu bimetallic complexes were synthesized and fully characterized. The influence of the triplet energy levels of the bridging ligands on the energy transfer (ET) process from the Ir(III) complexes to Eu(III) ions in solution was investigated at 77 K in Ir(III)/Eu(III) dyads. Photophysical experiment results show the bridging ligands play an important role in the ET process. Only when the triplet energy level of the bridging ligand was lower than the triplet metal-to-ligand charge transfer ((3)MLCT) energy level of the Ir moiety, was pure emission from the Eu(III) ion observed, implying complete ET took place from the Ir moiety to the Eu(III) ion. PMID:21931913

  11. Reforming the energy sector in transition economies: Selected experience and lessons. World Bank discussion paper

    SciTech Connect

    Gray, D.

    1995-08-01

    ;Contents: Background and Characteristics of the Energy Sector at the Beginning of the Reform Process; Energy Demand and Efficiency; Major Energy Production Issues in Central and Eastern Europe and Former Soviet Union; Changing Structure of East-West Energy Trade; Energy Pricing; Energy Sector Revenues and Finances; Experience in Energy Reform Commercialization, Privatization and Links to the Macroeconomy; Lessons, Conclusions and Approaches to Improve; and Annexes.

  12. Study of energy transfer mechanism from ZnO nanocrystals to Eu(3+) ions.

    PubMed

    Mangalam, Vivek; Pita, Kantisara; Couteau, Christophe

    2016-12-01

    In this work, we investigate the efficient energy transfer occurring between ZnO nanocrystals (ZnO-nc) and europium (Eu(3+)) ions embedded in a SiO2 matrix prepared using the sol-gel technique. We show that a strong red emission was observed at 614 nm when the ZnO-nc were excited using a continuous optical excitation at 325 nm. This emission is due to the radiative (5)D0 → (7)F2 de-excitation of the Eu(3+) ions and has been conclusively shown to be due to the energy transfer from the excited ZnO-nc to the Eu(3+) ions. The photoluminescence excitation spectra are also examined in this work to confirm the energy transfer from ZnO-nc to the Eu(3+) ions. Furthermore, we study various de-excitation processes from the excited ZnO-nc and their contribution to the energy transfer to Eu(3+) ions. We also report the optimum fabrication process for maximum red emission at 614 nm from the samples where we show a strong dependence on the annealing temperature and the Eu(3+) concentration in the sample. The maximum red emission is observed with 12 mol% Eu(3+) annealed at 450 °C. This work provides a better understanding of the energy transfer mechanism from ZnO-nc to Eu(3+) ions and is important for applications in photonics, especially for light emitting devices. PMID:26858155

  13. Strong luminescence and efficient energy transfer in Eu3+/Tb3+-codoped ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Luo, L.; Huang, F. Y.; Dong, G. S.; Fan, H. H.; Li, K. F.; Cheah, K. W.; Chen, J.

    2014-11-01

    Single crystalline Eu3+/Tb3+-codoped ZnO nanocrystals have been synthesized by using a simple co-precipitation method. Successful doping is realized so that strong green and red luminescence can be efficiently excited by ultraviolet and near ultraviolet radiation, demonstrating an efficient energy transfer from ZnO host to rare earth ions. The energy transfer from the ZnO host to Tb3+ in ZnO: Tb3+ samples and ZnO host to Eu3+ in the ZnO: Eu3+ samples under UV excitation are investigated. It is found that the red 5D0 → 7F2 emission of Eu3+ ions decreases with increasing temperature but the green 5D4 → 7F5 emission of Tb3+ ions increases with increasing temperature, implying a different energy transfer processes in the two samples. Moreover, energy transfer from Tb3+ ions to Eu3+ ions in ZnO nanocrystals is also observed by analyzing luminescence spectra and the decay curves. By adjusting the doping concentration, the Eu3+/Tb3+-codoped ZnO phosphors emit green and red luminescence with chromaticity coordinates near white light region, high color purity and high intensity, indicating that they are promising light-conversion materials and have potential in field emission display devices and liquid crystal display backlights.

  14. Learning Organizations and Policy Transfer in the EU: Greece's State Scholarships Foundation in a Reform-Resistant Context

    ERIC Educational Resources Information Center

    Lavdas, Kostas A.; Papadakis, Nikos E.; Rigopoulou, Yiota G.

    2012-01-01

    In the context of policy change in the EU, lifelong-learning has acquired a growing significance due to its promise to foster both professional development and personal fulfillment and thus contribute to the enhancement of social inclusion, active citizenship, competitiveness, and employability. The need for developing a smart and sustainable…

  15. Improved emission of Eu3+ by energy transfer via Tb3+ in coprecipitates TbxEu(1-x)(aspirin)3(phen)

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Xu, Z.; Qian, L.; Teng, F.; Xu, X. R.; Tao, D. L.

    2005-09-01

    In order to increase the red emission of Eu complex doped in poly(N-vinylcarbazole) (PVK), series of molar ratio coprecipitates [TbxEu(1-x)(aspirin)3(phen).H2O] (phen=1,10-phenanthroline) were prepared, in which Tb3+ ion acts as an energy bridge to enhance the energy transfer between the ligands and europium ion. The intramolecular energy transfer from Tb3+ to Eu3+ was studied via a time-resolved spectrum. It gave a direct evidence of the intramolecular energy transfer between the two lanthanide ions of terbium and europium. The photoluminescence and electroluminescence spectra as well as the performance of the device indium tin oxide/poly-(3,4-ethylenedioxythiophene):poly-(styrenesulphonic acid)/PVK:TbxEu(1-x)(aspirin)3(phen)/Al were also studied. Compared with that of PVK:Eu(aspirin)3phen device, the result showed an enhanced emission of Eu3+ ion due to the energy transfer via Tb3+ ion.

  16. Energy Transfer Process of Eu3+ Ions Doped in Tellurite Glass

    NASA Astrophysics Data System (ADS)

    Hong, Tran Thi; Dung, Phan Tien; Quang, Vu Xuan

    2016-05-01

    Tellurite glass doped with different concentrations of Eu3+ ions has been prepared by the conventional melting process. Photoluminescence, Raman spectra, phonon side-band spectra, and Judd-Ofelt analysis were carried out. Some spectroscopic parameters were estimated to predict the luminescence efficiency of the materials. The energy transfer between the rare-earth ions was observed, and a model for its cross-relaxation was proposed and quantitatively estimated. The charged intrinsic defects in the form of nonbridging oxygen (NBO) were determined, and the energy transfer between NBO and rare-earth ions observed. The energy-transfer-induced Eu3+ photoluminescence enhancement in tellurite glass is studied.

  17. Resonant energy transfer between Eu luminescent sites and their local geometry in GaN

    SciTech Connect

    Timmerman, Dolf; Wakamatsu, Ryuta; Tanaka, Kazuteru; Lee, Dong-gun; Koizumi, Atsushi; Fujiwara, Yasufumi

    2015-10-12

    Eu-doped GaN is a solid state material with promising features for quantum manipulation. In this study, we investigate the population dynamics of Eu in ions in this system by resonant excitation. From differences in the emission related to transitions between the {sup 5}D{sub 0} and {sup 7}F{sub 2} manifold in the Eu ions, we can distinguish different luminescence sites and observe that a resonant energy transfer takes place between two of these sites which are in proximity of each other. The time constants related to this energy transfer are on the order of 100 μs. By using different substrates, the energy transfer efficiency could be strongly altered, and it is demonstrated that the coupling between ions has an out-of-plane character. Based on these results, a microscopic model of this combined center is presented.

  18. Climate for Collaboration: Analysis of US and EU Lessons and Opportunities in Energy and Climate Policy

    SciTech Connect

    De Vita, A.; de Connick, H.; McLaren, J.; Cochran, J.

    2009-11-01

    A deepening of cooperation between the United States and the European Union requires mutual trust, and understanding of current policies, challenges and successes. Through providing such understanding among policymakers, industry and other stakeholders in both economies, opportunities for transatlantic cooperation on climate change and energy policy emerge. This paper sets out by discussing the environmental, legislative, and economic contexts of the EU and US as related to climate. This context is essential to understanding how cap-and-trade, renewable energy and sustainable transportation policies have taken shape in the EU and the US, as described in Chapter 3.1. For each of these policies, a barrier analysis and discussion is provided. Chapter 4 builds off this improved understanding to listobservations and possible lessons learned. The paper concludes with recommendations on topics where EU and US interests align, and where further cooperation could prove beneficial.

  19. Energy migration of the local excitation at the Eu3+ site in a Eu-O chemical cluster in sol-gel derived SiO2:Eu3+ glasses

    NASA Astrophysics Data System (ADS)

    Hayakawa, Tomokatsu; Nogami, Masayuki

    2001-09-01

    By using the fluorescence line-narrowing technique, we observed a broad fluorescence band in the vicinity of a resonant line of the 5D0→7F0 transition in an Eu3+-doped SiO2 glass synthesized by a sol-gel process. The comparison with a similar line in an Al2O3-SiO2:Eu3+ sol-gel glass revealed the existence of a chemical cluster of Eu3+ and O2- in the tetrahedral SiO4 network. The broad fluorescence band was attributable to an energy migration among the Eu3+ ions for the site-selectively received excitation energy. Also, based on Yokota-Tanimoto's energy diffusion model, the fluorescence decay curves for the 5D0→7F2 transition were closely correlated with the energy migration and gel-glass transformation. The gel-shrinkage and reduced interatomic distance between Eu3+ ions due to a thermal treatment at higher temperature definitely resulted in a decrease in the associated lifetime of the initial decay.

  20. Synthesis, luminescence properties, and energy transfer of novel CaWO4:Eu3+, Mn2+ red phosphor

    NASA Astrophysics Data System (ADS)

    Cao, Renping; Xu, Haidong; Peng, Dedong; Jiang, Shenhua; Luo, Zhiyang; Li, Wensheng; Yu, Xiaoguang

    2015-12-01

    Novel CaWO4:Eu3+, Mn2+ red phosphor is synthesized by solid-state reaction method in air. CaWO4:Eu3+, Mn2+ phosphor with excitation 268 and 394 nm emits red light with chromaticity coordinates (x = 0.6403, y = 0.3593). The strongest emission bands peaking at ∼615 nm is attributed to 5D0 → 7F2 of Eu3+ ion. Strong excitation band peaking at ∼394 nm indicates that the phosphor may be excited by near UV (∼394 nm) chip. Emission intensity of CaWO4:Eu3+, Mn2+ phosphor with excitation 268 nm is ∼2 times stronger than that of CaWO4:Eu3+ phosphor owing to energy transfer between Eu3+ ion and Mn2+ ion. Energy transfer from WO4 2 - group and Eu3+ ion to Mn2+ ion in CaWO4:Eu3+, Mn2+ phosphor may be explained via luminescence properties. Luminous mechanism is analyzed by energy level diagrams of WO4 2 - group, Mn2+ and Eu3+ ion. The paper content is helpful to develop and research other novel phosphors.

  1. Luminescence properties and energy transfer in Eu2+, Mn2+ codoped Na(Sr,Ba)PO4 phosphor

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong; Ni, Haiyong; Wang, Lingli

    2014-03-01

    Eu2+ and Mn2+ singly doped and codoped Na(Sr,Ba)PO4 phosphors were synthesized, and their luminescent properties were investigated. A broad blue emission and a broad orange emission band were observed in Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor. The resonant-type energy transfer from Eu2+ to Mn2+ was demonstrated, and the energy transfer efficiency was also calculated according to their emission spectra. Based on the principle of energy transfer, the emission intensity ration of Eu2+ and Mn2+ could be appropriately tuned by adjusting the contents of activators. Due to the strong absorption in the 250-400 nm range, Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor could be used as a potential candidate for near-UV white light-emitting diodes (LEDs).

  2. Synthesis, energy transfer and tunable emission properties of SrSb2O6:Eu(3+), Bi(3+) phosphor.

    PubMed

    Cao, Renping; Fu, Ting; Peng, Dedong; Cao, Chunyan; Ruan, Wen; Yu, Xiaoguang

    2016-12-01

    Host SrSb2O6, SrSb2O6:Bi(3+), SrSb2O6:Eu(3+), and SrSb2O6:Eu(3+), Bi(3+) phosphors are synthesized by solid state reaction method in air. Host SrSb2O6 with excitation 254nm shows weak green-yellow emission in the range of 320-780nm due to Sb(5+)→O(2-) transition. SrSb2O6:Bi(3+) phosphor with excitation 365nm emits green light within the range 400-650nm owing to the (3)P1→(1)S0 transition of Bi(3+) ion. SrSb2O6:Eu(3+) phosphor with excitation 254nm exhibits a systematically varied hue from green to orange-red light by increasing Eu(3+) concentration from 0 to 7mol%, and that with excitation 394nm only shows orange-red light. The optimal Eu(3+) concentration is ~4mol% in SrSb2O6:Eu(3+) phosphor. SrSb2O6:Eu(3+), Bi(3+) phosphor with excitation 254 and 394nm emits orange-red light. Emission intensity of SrSb2O6:Eu(3+) phosphor may be enhanced >2 times by co-doping Bi(3+) ion because of the fluxing agent and energy transfer roles of Bi(3+) ion in SrSb2O6:Eu(3+), Bi(3+) phosphor. The luminous mechanism of SrSb2O6:Eu(3+), Bi(3+) phosphor is analyzed and explained by the simplified energy level diagrams of Sb2O6(2-) group, Bi(3+) and Eu(3+) ions, and energy transfer processes between them. PMID:27380301

  3. Enhanced luminescence of SiO2:Eu3+ by energy transfer from ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Bang, Jungsik; Yang, Heesun; Holloway, Paul H.

    2005-08-01

    ZnO nanoparticles embedded into SiO2 by an ex situ method were shown to result in stable green emission with a peak at 510 nm compared to the normal peak at 495 nm from micron-sized ZnO powders. Green emission from ZnO nanoparticles was completely suppressed when they were embedded in SiO2 doped with Eu3+. Instead, the f-f emissions from Eu3+ were enhanced 5-10 times by energy transfer from the embedded ZnO nanoparticles to Eu3+. The Eu3+ luminescence increased as the Eu3+ concentration increased from 1 vs 5 mole % (for 10 mole % ZnO). In addition, the intensity increased as the embedded ZnO nanoparticles concentration increased up to 10 mole % (for 5 mole % Eu3+). The effects of phonon mediated energy transfer, quenching by activator interactions between Eu3+ ions, and energy back-transfer from Eu3+ ions to ZnO nanoparticles were discussed.

  4. Does EU's energy dependence on Russia increase price volatility for consumers?

    NASA Astrophysics Data System (ADS)

    Yekeler, Zeynep

    Europe's dependence on natural gas imports from Russia has raised questions about energy risk and the vulnerability of the European countries, especially after the supply cuts in 2006, 2008, 2009, and 2012. The implementation of the Third Energy Package to finally unify European energy markets by linking the states located on the periphery to the well connected gas hubs in Northern Europe has been slow due to a lack of political will across Europe. This has enabled Russian Gazprom to retain its position as a major player in European markets and hinder any European effort to diversify the energy portfolio of the region. Using residential natural gas and electricity price data from 2000 through 2014, this paper analyzes the impact of EU's import reliance on natural gas from Russia and the supply disruptions on the volatility of natural gas and electricity prices through a fixed effects regression model. Results indicate that while the size of Russian natural gas imports does not significantly affect natural gas and electricity price volatility in EU countries, security supply measures such as natural gas stocks matter, especially for Southeast European countries that consistently pay more according to the results. The paper concludes by discussing the importance of formulating policies that not only aim to reduce overall EU dependence but minimize Southeastern Europe's vulnerabilities. Policy suggestions include increasing cross-border interconnectors and storage capacity as well as increasing LNG import capacity by building regasification terminals in periphery countries like Greece, Bulgaria, Romania and Slovenia.

  5. The reform of energy subsidies for the enhancement of marine sustainability: An empirical analysis of energy subsidies worldwide and an in-depth case study of South Korea's energy subsidy policies

    NASA Astrophysics Data System (ADS)

    Shim, Jae Hyun

    This dissertation seeks to raise awareness about harmful effects of fossil fuel and nuclear energy subsidies that have blocked transition from conventional energy to a decarbonized, renewable energy system. Today, humans face daunting challenges in the form of global warming, which results mainly from the burning of fossil fuels. To avoid catastrophe, the transition to a renewable energy regime should be an urgent priority; however, the reality is that the progress of renewable energy is very slow due to the various political and economic factors when compared to conventional energy resources. A chief factor is that the energy subsidy for fossil fuel and nuclear energy obstructs the "level playing field" for renewable energy. Energy subsidies for conventional energy can be understood in the context of the commodification paradigm, which regards nature as an object of conquest and supports the principle of more is better. Although fossil fuel energy damages the environment, economy, and social equity, all countries subsidize such energy, no matter the country's state of development. This holds true as much in the U.S. and the EU as in China, India and South Korea. The oceans, which cover 71% of the earth, are threatened by the activities of conventional energy, which are underpinned by subsidies. These subsidies have contributed to the destruction of the marine ecosystem through increased GHG emissions like CO2 and NOx which cause a sea temperature increase and coral bleaching. Subsidies also significantly affect fishery overexploitation, oil pollution, and thermal pollution. In-depth empirical analysis of South Korea showed how fossil fuel and nuclear energy activities have threatened marine sustainability through thermal pollution, algae bloom (red tides), overexploitation, and oil-related marine pollution. Reforming subsidies of fossil fuel and nuclear energy should be a global priority because of imminent of global warming. As strategies for energy subsidy

  6. Electrospinning-derived Tb2(WO4)3:Eu3+nanowires: energy transfer and tunable luminescence properties

    NASA Astrophysics Data System (ADS)

    Hou, Zhiyao; Cheng, Ziyong; Li, Guogang; Wang, Wenxin; Peng, Chong; Li, Chunxia; Ma, Ping'an; Yang, Dongmei; Kang, Xiaojiao; Lin, Jun

    2011-04-01

    One-dimensional Tb2(WO4)3 and Tb2(WO4)3:Eu3+nanowires have been prepared by a combination method of sol-gel process and electrospinning. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. The as-obtained precursor samples present fiber-like morphology with uniform size, and Tb2(WO4)3 and Tb2(WO4)3:Eu3+nanowires were formed after annealing. Under ultraviolet excitation and low-voltage electron beams excitation into WO42-and the f-f transition of Tb3+, the Tb2(WO4)3 samples show the characteristic emission of Tb3+ corresponding to 5D4-7F6, 5, 4, 3 transitions due to an efficient energy transfer from WO42- to Tb3+, while Tb2(WO4)3:Eu3+ samples mainly exhibit the characteristic emission of Eu3+ corresponding to 5D0-7F0, 1, 2 transitions due to an energy transfer occurs from WO42- and Tb3+ to Eu3+. The increase of Eu3+ concentration leads to the increase of the energy transfer efficiency from Tb3+ to Eu3+. The PL color of Tb2(WO4)3:x mol% Eu3+ phosphors can be tuned from green to red easily by changing the doping concentration (x) of Eu3+, making the materials have potential applications in fluorescent lamps and color display fields.

  7. BaGdF5:Dy(3+),Tb(3+),Eu(3+) multifunctional nanospheres: paramagnetic, luminescence, energy transfer, and tunable color.

    PubMed

    Guan, Hongxia; Song, Yanhua; Zheng, Keyan; Sheng, Ye; Zou, Haifeng

    2016-05-18

    A series of Dy(3+),Tb(3+) and Eu(3+) singly, doubly or triply doped BaGdF5 phosphors were synthesized by a one-step hydrothermal method with l-arginine, and their energy transfer, migrations and multicolored luminescence properties were investigated in detail. The as-prepared Dy(3+),Tb(3+) or Eu(3+) doped samples showed strong blue, green and red emission, respectively. Different hues of green and red light were obtained by co-doped Dy(3+),Tb(3+) and Tb(3+),Eu(3+) in the BaGdF5 host, respectively. More significantly, in the Dy(3+),Tb(3+),Eu(3+) tri-doped BaGdF5 phosphors, colors changed from yellow green to orange red by adjusting the doping concentration of Eu(3+). Energy migrations from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) are reported in detail. Furthermore, the obtained samples exhibit paramagnetic properties at room temperature and low temperature. It is obvious that these Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped BaGdF5 nanomaterials with tunable multicolored luminescence properties may have potential applications in the fields of full-color displays, biological labels and bio-separation. PMID:27146322

  8. Tunable luminescence properties and energy transfer in LaAl11 O18 :Eu,Tb phosphor.

    PubMed

    Mendhe, M S; Puppalwar, S P; Dhoble, S J

    2016-05-01

    Eu(2+) and Tb(3+) singly doped and co-doped LaAl11 O18 phosphors were prepared by a combustion method using urea as a fuel. The phase structure and photoluminescence (PL) properties of the prepared phosphors were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence excitation and emission spectra. When the content of Eu(2+) was fixed at 0.01, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb(3+) ions from 0.01 to 0.03 through an energy transfer (ET) process. The fluorescence data collected from the samples with different contents of Tb(3+) into LaAl11 O18 : Eu, show the enhanced green emission at 545 nm associated with (5) D4 -(7) F5 transitions of Tb(3+) . The enhancement was attributed to ET from Eu(2+) to Tb(3+) , and therefore Eu(2+) ion acts as a sensitizer (an energy donor) while Tb(3+) ion as an activator. The ET from Eu(2+) to Tb(3+) is performed through dipole-dipole interaction. The ET efficiency and critical distance were also calculated. The present Eu(2+) -Tb(3+) co-doped LaAl11 O18 phosphor will have potential application for UV convertible white light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26592806

  9. Energy levels and lifetimes of Nd IV, Pm IV, Sm IV, and Eu IV

    SciTech Connect

    Dzuba, V. A.; Safronova, U. I.; Johnson, W. R.

    2003-09-01

    To address the shortage of experimental data for electron spectra of triply ionized rare-earth elements we have calculated energy levels and lifetimes of 4f{sup n+1} and 4f{sup n}5d configurations of Nd IV (n=2), Pm IV (n=3), Sm IV (n=4), and Eu IV (n=5) using Hartree-Fock and configuration-interaction methods. To control the accuracy of our calculations we also performed similar calculations for Pr III, Nd III, and Sm III, for which experimental data are available. The results are important, in particular, for physics of magnetic garnets.

  10. IPTS/ESTO Studies on Reforms of Agriculture, Education and Social Systems within the Context of Enlargement and Demographic Change in the EU. Final Report.

    ERIC Educational Resources Information Center

    2002

    This document summarizes a comparative analysis of the interconnections between technological and socioeconomic developments in agriculture and rural development, human capital formation, and social systems in the 13 candidate countries (CCs) for admission into the European Union (EU) and in the 15 countries of the EU. Specific topics considered…

  11. Current EU-27 technical potential of organic waste streams for biogas and energy production.

    PubMed

    Lorenz, Helge; Fischer, Peter; Schumacher, Britt; Adler, Philipp

    2013-11-01

    Anaerobic digestion of organic waste generated by households, businesses, agriculture, and industry is an important approach as method of waste treatment - especially with regard to its potential as an alternative energy source and its cost-effectiveness. Separate collection of biowaste from households or vegetal waste from public green spaces is already established in some EU-27 countries. The material recovery in composting plants is common for biowaste and vegetal waste. Brewery waste fractions generated by beer production are often used for animal feeding after a suitable preparation. Waste streams from paper industry generated by pulp and paper production such as black liquor or paper sludge are often highly contaminated with toxic substances. Recovery of chemicals and the use in thermal processes like incineration, pyrolysis, and gasification are typical utilization paths. The current utilization of organic waste from households and institutions (without agricultural waste) was investigated for EU-27 countries with Germany as an in-depth example. Besides of biowaste little is known about the suitability of waste streams from brewery and paper industry for anaerobic digestion. Therefore, an evaluation of the most important biogas process parameters for different substrates was carried out, in order to calculate the biogas utilization potential of these waste quantities. Furthermore, a calculation of biogas energy potentials was carried out for defined waste fractions which are most suitable for anaerobic digestion. Up to 1% of the primary energy demand can be covered by the calculated total biogas energy potential. By using a "best-practice-scenario" for separately collected biowaste, the coverage of primary energy demand may be increased above 2% for several countries. By using sector-specific waste streams, for example the German paper industry could cover up to 4.7% and the German brewery industry up to 71.2% of its total energy demand. PMID:23849753

  12. Host absorption sensitizing and energy transfer to Eu³⁺ by Gd³⁺ in Ba₆Gd{sub 2–x}Na₂Eu{sub x}(PO₄)₆F₂

    SciTech Connect

    Xie, Mubiao; Liang, Hongbin; Huang, Yan; Gao, Zhenhua; Tao, Ye

    2013-05-01

    Eu³⁺ activated fluoro-apatite phosphors Ba₆Gd{sub 2–x}Na₂Eu{sub x}(PO₄)₆F₂ were synthesized using the traditional high temperature solid state reaction method, and their VUV–vis spectroscopic properties of Eu³⁺ were studied. The results show that phosphor Ba₆Gd₁.₉₀Na₂Eu₀.₁₀(PO₄)₆F₂ has intense absorption in the VUV range because of Gd³⁺ ions as sensitizers. The energy transfer process from Gd³⁺ to Eu³⁺ in Ba₆Gd{sub 2-x}Na₂Eu{sub x}(PO₄)₆F₂ were investigated and discussed in terms of luminescence spectra and decay curves, showing that the energy transfer of Gd³⁺→Eu³⁺ is efficient. - Graphical abstract: The Gd³⁺ ions can enhance the host-related absorption in VUV range. The energy transfer from Gd³⁺ to Eu³⁺ ions is efficient. Highlights: • The Gd³⁺ ions play an important role in enhancing the host-related absorption in VUV range. • The charge-transfer energy of Eu³⁺ decreases from Ca²⁺ to Sr²⁺ and Ba²⁺ in M₆Gd₁.₉₀Na₂Eu₀.₁₀(PO₄)₆F₂ (M=Ca, Sr, Ba). • There is efficient energy transfer from Gd³⁺ to Eu³⁺ in Ba₆Gd{sub 2–x}Na₂Eu{sub x}(PO₄)₆F₂.

  13. Photoluminescence, energy transfer and tunable color of Ce(3+), Tb(3+) and Eu(2+) activated oxynitride phosphors with high brightness.

    PubMed

    Lü, Wei; Huo, Jiansheng; Feng, Yang; Zhao, Shuang; You, Hongpeng

    2016-06-21

    New tuneable light-emitting Ca3Al8Si4O17N4:Ce(3+)/Tb(3+)/Eu(2+) oxynitride phosphors with high brightness have been prepared. When doped with trivalent cerium or divalent europium they present blue luminescence under UV excitation. The energy transfer from Ce(3+) to Tb(3+) and Ce(3+) to Eu(2+) ions is deduced from the spectral overlap between Ce(3+) emission and Tb(3+)/Eu(2+) excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail, and the mechanisms of energy transfer from the Ce(3+) to Tb(3+) and Ce(3+) to Eu(2+) ions are demonstrated to be a dipole-quadrupole and dipole-dipole mechanism, respectively, by the Inokuti-Hirayama model. The International Commission on Illumination value of color tuneable emission as well as luminescence quantum yield (23.8-80.6%) can be tuned by controlling the content of Ce(3+), Tb(3+) and Eu(2+). All results suggest that they are suitable for UV light-emitting diode excitation. PMID:27226201

  14. Photoluminescence and energy transfer properties of Eu2+ and Tb3+ co-doped gamma aluminum oxynitride powders

    NASA Astrophysics Data System (ADS)

    Zhang, Jiantao; Ma, Chaoyang; Wen, Zicheng; Du, Miaomiao; Long, Jiaqi; Ma, Ran; Yuan, Xuanyi; Li, Junting; Cao, Yongge

    2016-08-01

    Gamma-AlON: 0.2Eu2+, Tb3+ phosphors were firstly synthesized via a high temperature solid-state reaction. For the phosphors, luminescence properties as well as energy transfer mechanism were investigated in detail. The energy transfer from Eu2+ to Tb3+ in the γ-AlON host was ascribed to the dipole-dipole mechanism, and the efficiency and critical distance in the energy transfer process were also estimated. γ-AlON: 0.2Eu2+, Tb3+ phosphors showed a broad-band emission centered at about 405 nm and other several emission peaks, which were assigned to the 5d-4f transition of Eu2+ ions and the 5D4-7FJ (J = 6, 5, 4, and 3) characteristic transitions of Tb3+ ions, respectively. The results indicated that γ-AlON: 0.2Eu2+, Tb3+ phosphors have great potential application in white light-emitting diodes due to its broad-band excitation in the ultraviolet range and the high-efficient green light emission.

  15. Energy transfer from Sm3+ to Eu3+ in red-emitting phosphor LaMgAl11O19:Sm3+, Eu3+ for solar cells and near-ultraviolet white light-emitting diodes.

    PubMed

    Min, Xin; Huang, Zhaohui; Fang, Minghao; Liu, Yan-Gai; Tang, Chao; Wu, Xiaowen

    2014-06-16

    The red-emitting phosphor LaMgAl11O19:Sm(3+), Eu(3+) was prepared by solid-state reaction at 1600 °C for 4 h. The phase formation, luminescence properties, and energy transfer from Sm(3+) to Eu(3+) were studied. With the addition of 5 mol % Sm(3+) as the sensitizer, the excitation wavelength of LaMgAl11O19:Eu(3+) phosphor was extended from 464 to 403 nm, and the emission intensity under the excitation at 403 nm was also enhanced. The host material LaMgAl11O19 could contain the high doping content of Eu(3+) (20 mol %) without concentration quenching. This energy transfer from Sm(3+) to Eu(3+) was confirmed by the decay times of energy donor Sm(3+). The mechanism of energy transfer (Sm(3+) → Eu(3+)) was proved to be quadrupole-quadrupole interaction. Under the 403 nm excitation at 150 °C, the emission intensities of the characteristic peaks of Sm(3+) and Eu(3+) in LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor were decreased to 65% and 56% of the initial intensities at room temperature, and the relatively high activation energy proved that this phosphor had a good thermal stability. The CIE coordinate was calculated to be (x = 0.601, y = 0.390). The LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor is a candidate for copper phthalocyanine-based solar cells and white light-emitting diodes. PMID:24884208

  16. Developing an energy efficient steam reforming process to produce hydrogen from sulfur-containing fuels

    NASA Astrophysics Data System (ADS)

    Simson, Amanda

    Hydrogen powered fuel cells have the potential to produce electricity with higher efficiency and lower emissions than conventional combustion technology. In order to realize the benefits of a hydrogen fuel cell an efficient method to produce hydrogen is needed. Currently, over 90% of hydrogen is produced from the steam reforming of natural gas. However, for many applications including fuel cell vehicles, the use of a liquid fuel rather than natural gas is desirable. This work investigates the feasibility of producing hydrogen efficiently by steam reforming E85 (85% ethanol/15% gasoline), a commercially available sulfur-containing transportation fuel. A Rh-Pt/SiO2-ZrO2 catalyst has demonstrated good activity for the E85 steam reforming reaction. An industrial steam reforming process is often run less efficiently, with more water and at higher temperatures, in order to prevent catalyst deactivation. Therefore, it is desirable to develop a process that can operate without catalyst deactivation at more energy efficient conditions. In this study, the steam reforming of a sulfur-containing fuel (E85) was studied at near stoichiometric steam/carbon ratios and at 650C, conditions at which catalyst deactivation is normally measured. At these conditions the catalyst was found to be stable steam reforming a sulfur-free E85. However, the addition of low concentrations of sulfur significantly deactivated the catalyst. The presence of sulfur in the fuel caused catalyst deactivation by promoting ethylene which generates surface carbon species (coke) that mask catalytic sites. The amount of coke increased during time on stream and became increasingly graphitic. However, the deactivation due to both sulfur adsorption and coke formation was reversible with air treatment at 650°C. However, regenerations were found to reduce the catalyst life. Air regenerations produce exotherms on the catalyst surface that cause structural changes to the catalyst. During regenerations the

  17. EVA thin film with thermo- and moisture-stable luminescent copolymer beads composed of Eu(III) complexes for improvement of energy conversion efficiency on silicon solar cell

    NASA Astrophysics Data System (ADS)

    Kataoka, Hisataka; Omagari, Shun; Nakanishi, Takayuki; Hasegawa, Yasuchika

    2015-04-01

    Luminescent beads composed of Eu(hfa)3(TPPO)2 (hfa: hexafluoroacetylacetonate, TPPO: triphenylphosphine oxide) in PMMA copolymer (polymethylmethacrylate- styrene and polymethylmethacrylate-trifluoromethylmethacrylate copolymers), PMMA-St-Eu and PMMA-TF-Eu have been reported for improvement of energy conversion efficiency on silicon solar cell. The PMMA-St-Eu and PMMA-TF-Eu beads are prepared using radical initiator AIBN (2,2-azobisisobutyronitrile) without BPO (Benzoyl peroxide) which promotes decomposition of Eu(hfa)3(TPPO)2. The emission properties of EVA (ethylene vinyl acetate) film with PMMA-St-Eu or PMMA-TF-Eu beads are characterized by the emission spectra and lifetimes. Thermo- and moisture-stabilities of the EVA films are performed under high temperature and high moisture condition (85°C85%RH). Increase percentage the solar cell short circuit current efficiency in the solar cell modulation using with EVA film containing PMMA-St-Eu beads with size in 70 μm was estimated to 1.2%. Thermo- and moisture-stable PMMA-St-Eu and PMMA-TF-Eu beads for solar sealing film are demonstrated for the first time.

  18. [The Synthesis, Luminescence and Energy Transmission of NaLa(MoO4) 2 : Eu3+/Tb3+/Tm3+ Materials].

    PubMed

    Xu, Jing; Yan, Jing-hui; Han, Yu-ting; Qiao, Shu-liang; Yang, Bo; Li, Li; Liu, Cai-hong; Yau, Shuang; Zou, Ming-qiang

    2015-10-01

    A series of Eu3+ /Tb3+ /Tm3+ single/co-doped NaLa(MoO4)2 (NLM) phosphors have been synthesized by microemulsion-hydrothermal method. Phosphor crystal structure, morphology and luminescent properties were tested and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. The results show that the prepared samples are all tetragonal single crystals. By way of substitution, the sites of La3+ are replaced by Eu3+, Tb3+ and Tm3+. Morphology of the samples are tetragonal sheet structure and the size of particles is 1 - 1.5 μm. When the doping concentration of Eu3+ is 9%, NLM : 9%Eu3+ phosphor emission peak is the strongest at 616 nm, the critical transfer distance (R(c)) between Eu3+ in the NLM matrix is about 15.20 Å at this time. At the emission spectrum of NLM : 9%Eu3+, the peak at 591 nm is the magnetic dipole transition of 5D0 to 7F1 of Eu3+. The peak at 616 nm is the electric dipole transition of 5D0 to 7 F2 of Eu3+. Electric dipole transition emission intensity is about 10 times of the strength of the magnetic dipole transition. This indicates that Eu3+ is located at noninversion symmetry site. By Fixing Eu3+ (Tb3+) concentration and varying the concentration of Tb3+ (Eu3+), the energy transfer mechanism between Eu3+ and Tb3+ was studied. By adjusting the Eu3+, Tb3+ and Tm3+ doping concentrations, tunable luminescence of visible light region is implemented under the single matrix. The luminescence of NLM x%Eu3+, y%Tb3+, z%Tm3+ phosphors are translated from blue (0.205, 0.135) to pseudo-white (0.305, 0.266) under 360 nm irradiation. PMID:26904805

  19. Energy-efficient syngas production through catalytic oxy-methane reforming reactions.

    PubMed

    Choudhary, Tushar V; Choudhary, Vasant R

    2008-01-01

    The considerable recent interest in the conversion of stranded methane into transportable liquids as well as fuel cell technology has provided a renewed impetus to the development of efficient processes for the generation of syngas. The production of syngas (CO/H2), a very versatile intermediate, can be the most expensive step in the conversion of methane to value-added liquid fuels. The catalytic oxy reforming of methane, which is an energy-efficient process that can produce syngas at extremely high space-time yields, is discussed in this Review. As long-term catalyst performance is crucial for the wide-scale commercialization of this process, catalyst-related studies are abundant. Correspondingly, herein, emphasis is placed on discussing the different issues related to the development of catalysts for oxy reforming. Important aspects of related processes such as catalytic oxy-steam, oxy-CO2, and oxy-steam-CO2 processes will also be discussed. PMID:18188848

  20. Methodology and estimation of the welfare impact of energy reforms on households in Azerbaijan

    NASA Astrophysics Data System (ADS)

    Klytchnikova, Irina

    This dissertation develops a new approach that enables policy-makers to analyze welfare gains from improvements in the quality of infrastructure services in developing countries where data are limited and supply is subject to interruptions. An application of the proposed model in the former Soviet Republic of Azerbaijan demonstrates how this approach can be used in welfare assessment of energy sector reforms. The planned reforms in Azerbaijan include a set of measures that will result in a significant improvement in supply reliability, accompanied by a significant increase in the prices of energy services so that they reach the cost recovery level. Currently, households in rural areas receive electricity and gas for only a few hours a day because of a severe deterioration of the energy infrastructure following the collapse of the Soviet Union. The reforms that have recently been initiated will have far-reaching poverty and distributional consequences for the country as they result in an improvement in supply reliability and an increase in energy prices. The new model of intermittent supply developed in this dissertation is based on the household production function approach and draws on previous research in the energy reliability literature. Since modern energy sources (network gas and electricity) in Azerbaijan are cleaner and cheaper than the traditional fuels (fuel wood, etc.), households choose modern fuels whenever they are available. During outages, they rely on traditional fuels. Theoretical welfare measures are derived from a system of fuel demands that takes into account the intermittent availability of energy sources. The model is estimated with the data from the Azerbaijan Household Energy Survey, implemented by the World Bank in December 2003/January 2004. This survey includes an innovative contingent behavior module in which the respondents were asked about their energy consumption patterns in specified reform scenarios. Estimation results strongly

  1. Near infrared emission and energy transfer in Eu2+ - Nd3+ co-doped Ca2BO3Cl

    NASA Astrophysics Data System (ADS)

    Talewar, R. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Novel near infrared (NIR) emitting phosphor, Ca2BO3Cl:Eu2+, Nd3+ was synthesized by conventional solid-state reaction and characterized with X-ray diffraction, photoluminescence emission, photoluminescence excitation spectra and fluorescence decay measurements. When excited with 400 nm, the phosphor gives broadband emission at 560 nm, which corresponds to the allowed 5d → 4f transition of Eu2+ and an intense NIR emissions in the range 800-1400 nm, which are assigned to the characteristic 4I9/2,11/2,13/2 transitions of Nd3+ ions. The dependence of visible and NIR emissions, decay lifetime and the energy transfer efficiency (ηETE) were investigated in detail. The luminescence spectra, both in visible (VIS) and NIR regions, and decay lifetime curves of Eu2+ have been measured to prove energy transfer (ET) from Eu2+ to Nd3+. These results demonstrate the possibility for enhancing the photovoltaic conversion efficiency of silicon solar cell by modifying the absorption and utilizing the UV to blue part of the solar spectrum where the efficiency of c-Silicon solar cell is low.

  2. Homogeneous one-dimensional structured Tb(OH){sub 3}:Eu{sup 3+} nanorods: Hydrothermal synthesis, energy transfer, and tunable luminescence properties

    SciTech Connect

    Yang Jun; Li Guogang; Peng Chong; Li Chunxia; Zhang Cuimiao; Fan Yong; Xu Zhenhe; Cheng Ziyong; Lin Jun

    2010-02-15

    Nearly monodisperse, homogeneous and well-defined one-dimensional Tb{sub (1-x)}(OH){sub 3}:xEu{sup 3+} (x=0-3 mol%) nanorods have been prepared through hydrothermal method. The size of the Tb(OH){sub 3}:Eu{sup 3+} rods could be modulated from nano- to micro-scale by using different amount of ammonia solution. They present highly crystallinity in spite of the moderate reaction temperature. Under ultraviolet excitation into the f->f transition of Tb{sup 3+} at 382 nm, Tb(OH){sub 3} samples show the characteristic emission of Tb{sup 3+} corresponding to {sup 5}D{sub 4}->{sup 7}F{sub 6,5,4,3} transitions; whereas Tb(OH){sub 3}:Eu{sup 3+} samples mainly exhibit the characteristic emission of Eu{sup 3+} corresponding to {sup 5}D{sub 0}->{sup 7}F{sub 1,2,4} transitions due to an efficient energy transfer occurs from Tb{sup 3+} to Eu{sup 3+}. The increase of Eu{sup 3+} concentration leads to the increase of the energy transfer efficiency from Tb{sup 3+} to Eu{sup 3+}. The PL colors of Tb(OH){sub 3}:xEu{sup 3+} phosphors can be easily tuned from green, yellow, orange, to red by changing the doping concentration (x) of Eu{sup 3+}. - Graphical abstract: The colors of Tb(OH){sub 3}:xEu{sup 3+} phosphors can be easily tuned from green, yellow, orange, to red due to different energy transfer occurs from Tb{sup 3+} to Eu{sup 3+}.

  3. Geant4 simulation of the CERN-EU high-energy reference field (CERF) facility.

    PubMed

    Prokopovich, D A; Reinhard, M I; Cornelius, I M; Rosenfeld, A B

    2010-09-01

    The CERN-EU high-energy reference field facility is used for testing and calibrating both active and passive radiation dosemeters for radiation protection applications in space and aviation. Through a combination of a primary particle beam, target and a suitable designed shielding configuration, the facility is able to reproduce the neutron component of the high altitude radiation field relevant to the jet aviation industry. Simulations of the facility using the GEANT4 (GEometry ANd Tracking) toolkit provide an improved understanding of the neutron particle fluence as well as the particle fluence of other radiation components present. The secondary particle fluence as a function of the primary particle fluence incident on the target and the associated dose equivalent rates were determined at the 20 designated irradiation positions available at the facility. Comparisons of the simulated results with previously published simulations obtained using the FLUKA Monte Carlo code, as well as with experimental results of the neutron fluence obtained with a Bonner sphere spectrometer, are made. PMID:20511404

  4. Quantum effect on the energy levels of Eu2+ doped K2Ca2(SO4)3 nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2010-09-01

    Quantum confinement effect on the energy levels of Eu(2+) doped K(2)Ca(2)(SO(4))(3) nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu(2+) doped K(2)Ca(2)(SO(4))(3) microcrystalline sample observed at ∼436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f(6)5d energy level of Eu(2+). Energy band gap values of the micro and nanocrystalline K(2)Ca(2)(SO(4))(3) samples were also determined by measuring the UV-visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises. PMID:20386964

  5. Energy transfer between Eu-Mn and photoluminescence properties of Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ solid solution

    NASA Astrophysics Data System (ADS)

    Zhou, Jun; Wang, Yuhua; Liu, Bitao; Li, Feng

    2010-08-01

    In order to evaluate the energy transfer between Eu-Mn in Ba0.75Al11O17.25-BaMgAl10O17 solid solution, Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ phosphors were prepared by flux method. The crystal structure and the morphology of the solid solution were demonstrated by x-ray dirrfactometer and scanning electron microscopy. The photoluminescence mechanisms were explained by the energy transfer of Eu2+ to Mn2+ and the Dexter theory. A redshift of green emission peak and a decrease in decay time with the increase in Mn2+ concentration were observed. These phenomena are attributed to the formation of Mn2+ paired centers after analysis by a method of Pade approximations.

  6. Eu doping and reduction into barium orthophosphates

    NASA Astrophysics Data System (ADS)

    Santos, Ricardo D. S.; dos S. Rezende, Marcos V.

    2016-08-01

    We investigated Eu3+ and Eu2+ ion incorporation and the reduction of Eu3+ ions in a LiBaPO4 lattice using atomistic simulations based on lattice energy minimization. We predicted the most probable sites occupied by Eu3+ and Eu2+ ions, and the related charge-compensation mechanisms involved in these substitutions to the most provable reduction agent for Eu reduction. It was found that Eu3+and Eu2+ ions are the most energetically favorable for incorporation at Ba site. In the case of the Eu3+ ion, charge compensation by the LiBa‧ antisite is the most provable. Eu3+ reduction involving a H2 reduction atmosphere is the most favorable. Our results reveal that Eu3+ and Eu2+ position plays an important role in the luminescence characteristic and in the persistent luminescence mechanisms related to LiBaPO4.

  7. Color tunable phosphor CaMoO{sub 4}:Eu{sup 3+},Li{sup +} via energy transfer of MoO{sub 4}{sup 2−}–Eu{sup 3+} dependent on morphology and doping concentration

    SciTech Connect

    Bao, Xiaoyi; Zhou, Shengping; Wang, Jiaguo; Zhang, Lijie; Huang, Shaoming; Pan, Yuexiao

    2013-03-15

    Graphical abstract: Nanostructured phosphor CaMoO{sub 4}:Eu{sup 3+},Li{sup +} with various delicate morphologies has been obtained by molten salt synthesis. The luminescent color and the morphology of the phosphor are tuned by controlling the sintering temperature and the molar ratio of salt KCl to molybdates CaMoO{sub 4}. Highlights: ► Phosphor CaMoO{sub 4}:Eu{sup 3+},Li{sup +} with various delicate morphologies has been obtained. ► Energy transfer MoO{sub 4}{sup 2−} → Eu{sup 3+} is dependent on morphology and doping concentration. ► The luminescent color can be tuned by controlling energy transfer of MoO{sub 4}{sup 2−}–Eu{sup 3+}. - Abstract: The cooling rate and the solubility of molybdate in molten salt play crucial roles on the microscopic morphologies and photoluminescence (PL) properties of the phosphor CaMoO{sub 4}:Eu{sup 3+},Li{sup +}. Undoped CaMoO{sub 4} exhibits self-activated green PL with a broad emission band which is assigned to the spin forbidden {sup 3}T{sub 1,2}–{sup 1}A{sub 1} transition of the MoO{sub 4}{sup 2−} complex. The strong UV absorption of undoped CaMoO{sub 4} is originated from the charge transfer from O{sup 2−} ligands to the central Mo{sup 6+} ions inside MoO{sub 4}{sup 2−} group. The emission of the phosphor CaMoO{sub 4}:Eu{sup 3+},Li{sup +} obtained by molten salt synthesis (MSS) at 900 °C is composed of a broad green emission from MoO{sub 4}{sup 2−} and a group of sharp red emission peaks from f–f transitions of Eu{sup 3+}. Efficient energy transfer from MoO{sub 4}{sup 2−} to Eu{sup 3+} is responsible for the increased red PL of the phosphor. The dependence of energy transfer efficiency on the processing conditions and doping concentration has been investigated.

  8. Analysis of an energy recovery system for reformate-based PEM fuel cells involving a binary two-phase mixture

    NASA Astrophysics Data System (ADS)

    Cao, Yiding

    A comprehensive analysis on a novel energy recovery system for reformate-based proton exchange membrane (PEM) fuel cell systems is presented. The energy recovery system includes a throttling valve, a heat exchanger, a compressor, and is coupled with a coolant loop for the fuel cell stack. The feed stock of the fuel reformer, which is primarily a mixture of water and fuel, is vaporized in the heat exchanger and is then compressed to a sufficiently high pressure before it is ducted into the fuel reformer. The analysis includes the throttling of two-phase fuel/water mixture and vaporization in the heat exchanger to obtain the temperature and pressure of the mixture at the inlet of the compressor. The results indicate that the power plant efficiency with the energy recovery system can be increased by more than 20% compared to that of a fuel cell power plant without the energy recovery system. Additionally, more than 25% of the waste heat generated by the fuel cell stack can be removed due to the energy recovery system, and the fuel burned for the fuel reforming purpose is reduced by more than 70%.

  9. Luminescent properties and energy transfer of double-emitting Na2SrMgP2O8:Eu2+, Mn2+ phosphor

    NASA Astrophysics Data System (ADS)

    Wanjun, Tang; Shanshan, Hu; Fen, Zhang

    2013-10-01

    Olgite-type Na2SrMgP2O8 doped with Eu2+ and Mn2+ solely or doubly were prepared by a combustion-assisted synthesis method. The phase formation was confirmed by X-ray powder diffraction measurement. Upon excitation of 352 nm ultraviolet (UV) light, two intense broad bands have clearly been observed due to the allowed 5d-4f transition of Eu2+ and the forbidden 4T1-6A1 transition of Mn2+, respectively. On the basis of the luminescence spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu2+ to Mn2+ ions occur in the codoped Na2SrMgP2O8:Eu2+, Mn2+ phosphor. The composition-optimized Na2Sr0.99MgP2O8:0.01Eu2+ and Na2Sr0.99Mg0.9P2O8: 0.01Eu2+, 0.1Mn2+ phosphors exhibits superior external quantum efficiency (87.2% and 69.3%, respectively). Based on the principle of energy transfer, the relative intensities of blue and red emission could be tuned by adjusting the contents of Eu2+ and Mn2+.

  10. Luminescence properties and energy transfer of Ba2Mg(PO4)2:Eu2+, Mn2+ phosphor synthesized by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Xu, Shumian; Tang, Ke; Zhu, Dachuan; Han, Tao

    2015-04-01

    The Ba2Mg(PO4)2:Eu2+, Mn2+ phosphor is synthesized by a co-precipitation method. Crystal phase, morphology, excitation and emission spectra of sample phosphors are analyzed by XRD, SEM and FL, respectively. The results indicate particles synthesized by a co-precipitation method have a smaller size in diameter than that synthesized by conventional solid-state reaction method. Emission spectra of BMP:Eu2+, Mn2+ phosphor show a broad blue and a broad yellow emission bands with two peaks at about 456 nm and 575 nm under 380 nm excitation. An overlap between Eu2+ emission band and Mn2+ excitation band proves the existence of energy transfer from Eu2+ to Mn2+. Emitting color of the BMP:Eu2+, Mn2+ phosphor could be tuned by adjusting relative contents of Eu2+ and Mn2+ owing to energy transfer formula. Therefore, BMP:Eu2+, Mn2+ may be considered as a potential candidate for phosphor for near-UV white LED.

  11. Correlated color temperature tunability and energy transfer phenomenon in the NaBaBO3:Dy3+/Eu3+ phosphor for white light application

    NASA Astrophysics Data System (ADS)

    Zheng, Jianghui; Cheng, Qijin; Zheng, Cheng; Chen, Guo; Shi, Feng; Chen, Chao

    2015-08-01

    NaBa0.97-xBO3 0.03Dy3+, xEu3+(0 ≤ x ≤ 0.09) single-phase white phosphors with tunable correlated color temperature (CCT) were synthesized using a conventional solid state reaction method. The phase structure and luminescence properties of the as-prepared samples were investigated. The Dy3+, Eu3+ doped and Dy3+/Eu3+ co-doped NaBaBO3 phosphors excited by 361 nm show two blue and yellow emissions corresponding to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions and two red emissions due to the 5D0 → 4FJ (J = 1, 2) transitions of Eu3+ ions. Under 361-nm light excitation, the NaBa0.97-xBO3 0.03 Dy3+, xEu3+(0 ≤ x ≤ 0.09) phosphors feature a white light emitting property. Through the Commission Internationale de L'Eclairage (CIE) chromaticity analysis and CCT calculation, the CIE chromaticity coordinates of the emission light are all located in the white region and can be tuned from bluish white light to reddish white light when the Eu3+ concentration increases, and the CCT values of the obtained samples can vary from 5514.31 K to 8269.42 K. Furthermore, the energy transfer phenomenon from Dy3+ ions to Eu3+ ions in Dy3+/Eu3+ co-doped samples was also investigated. The results indicated that, through tuning the Eu3+ concentration of the NaBaBO3:Dy3+/Eu3+ phosphors, the NaBaBO3-based phosphor can act as a potential single-phase white emitting phosphor for the application in the near-ultraviolet (NUV) white light emitting diodes.

  12. Energy transfer from Tb{sup 3+} to Eu{sup 2+} in Ga{sub 2}S{sub 3}:(Eu{sup 2+}, Tb{sup 3+}) crystals

    SciTech Connect

    Tagiev, O. B. Ganbarova, Kh. B.

    2015-04-15

    The photoluminescence of Ga{sub 2}S{sub 3} crystals activated with Eu{sup 2+} and Tb{sup 3+} ions separately and with ions of both types is studied in the temperature range 77–300 K. It is established that, in the range 77–300 K, the observed broadband photoluminescence in (Ga{sub 2}S{sub 3}){sub 0.95}:(Eu{sub 2}O{sub 3}){sub 0.05} crystals with a peak at 545 nm is defined by 4f{sup 6}5d-4f{sup 7}({sup 8}S{sub 7/2}) intracenter transitions in Eu{sup 2+} ions and the photoluminescence with peaks at 492, 544, 584, 625, and 680 nm in (Ga{sub 2}S{sub 3}){sub 0.99}(Tb{sub 2}O{sub 3}){sub 0.01} crystals is due to the 5d → {sup 2}F{sub j} (j = 6−2) intracenter transitions in Tb{sup 3+} ions. It is shown that the photoluminescence bands of Tb{sup 3+} ions in the (Ga{sub 2}S{sub 3}){sub 0.94}(Eu{sub 2}O{sub 3}){sub 0.05}(Tb{sub 2}O{sub 3}){sub 0.01} crystals disappears because of excitation energy transfer from Tb{sup 3+} ions to Eu{sup 2+} ions; i.e., the Tb{sup 3+} ion is a sensitizer of the photoluminescence of the Eu{sup 2+} ion.

  13. Experimental determination of energy transfer in Eu(III) complexes, based on pyrazole substituted 1, 3-diketones

    NASA Astrophysics Data System (ADS)

    Varaksina, E. A.; Ambrozevich, S. A.; Datskevich, N. P.; Taydakov, I. V.; Vitukhnovsky, A. G.

    2016-01-01

    We succeeded in synthesis of the novel Eu-based luminophore with almost 100% efficiency of energy transfer from ligands to the lanthanide ion. The luminophores with β- diketonate ligands were characterized by means of optical spectroscopy. Impact of different types of β-diketonates on the quantum yield of luminescence was revealed. A β-diketonate complex exhibiting the highest luminescence quantum yield and prospective for OLED applications was determined. The reasons for decreasing quantum efficiencies for other types of investigated ligands are discussed.

  14. Luminescence properties and energy transfer of Eu/Mn-coactivated Mg2Al4Si5O18 as a potential phosphor for white-light LEDs.

    PubMed

    Chen, Jian; Liu, Yangai; Fang, Minghao; Huang, Zhaohui

    2014-11-01

    A series of blue-to-white emitting Mg2Al4Si5O18: Eu(2+), Mn(2+) phosphors were synthesized via high-temperature solid-state method, and their luminescence properties were investigated in detail. Under near-ultraviolet (UV) light excitation of 365 nm, Eu(2+)-doped Mg2Al4Si5O18 exhibits a broad blue emission band peaked at 469 nm, and Mn(2+)-doped Mg2Al4Si5O18 shows a broad orange-red emission band near 600 nm. The energy transfer from Eu(2+) to Mn(2+) in Mg2Al4Si5O18 host matrix can be found, and the resonant type is demonstrated by a dipole-quadrupole mechanism. The emission hue can be tuned from blue (0.17, 0.17) to bluish green (0.22, 0.29) and finally to white (0.31, 0.33) by properly varying the ratio of Eu(2+)/Mn(2+). The thermal quenching property of the sample was investigated, and the activation energy ΔE was estimated to be 0.30 eV. Additionally, the energy transfer critical distance between Eu(2+) and Mn(2+) was calculated. With appropriate tuning of activator content, the Mg2Al4Si5O18: Eu(2+), Mn(2+) phosphor may have potential application for UV light-emitting diodes. PMID:25325837

  15. Broadband Yellowish-Green Emitting Ba4Gd3Na3(PO4)6F2:Eu(2+) Phosphor: Structure Refinement, Energy Transfer, and Thermal Stability.

    PubMed

    Fu, Xiaopeng; Lü, Wei; Jiao, Mengmeng; You, Hongpeng

    2016-06-20

    A series of Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors with a broad emitting band have been synthesized by a traditional solid state reaction. The crystal structural and photoluminescence properties of Ba4Gd3Na3(PO4)6F2:Eu(2+) are investigated. The different crystallographic sites of Eu(2+) in Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors have been verified by means of their photoluminescence (PL) properties and decay times. Energy transfer between Eu(2+) ions, analyzed by excitation, emission, and PL decay behavior, has been indicated to be a dipole-dipole mechanism. Moreover, the luminescence quantum yield as well as the thermal stability of the Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor have been investigated systematically. The as-prepared Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor can act as a promising candidate for n-UV convertible white LEDs. PMID:27249557

  16. Luminescence and energy transfer of the color-tunable phosphor Li₆Gd(BO₃)₃:Tb³⁺/Bi³⁺, Eu³⁺.

    PubMed

    Chen, Peican; Mo, Fuwang; Guan, Anxiang; Wang, Rongfang; Wang, Guofang; Xia, Siyu; Zhou, Liya

    2016-02-01

    Bi(3+)/Tb(3+), Eu(3+) co-doped Li6Gd(BO3)3 (LGBO) phosphors were synthesized via a traditional solid-state method. Phase purity was investigated using X-ray diffraction, absorption strength of the phosphors were investigated by UV-vis absorption spectra, and the photoluminescence properties of the phosphors were studied systematically. Results showed that the emission intensity of Bi(3+), Eu(3+) co-doped LBOG was 2.76 times higher than that of Eu(3+)-doped LGBO irradiated at 275 nm, thereby implying the possibility of energy transfer from Bi(3+) to Eu(3+). The excitation spectra of Tb(3+), Eu(3+) co-doped LGBO phosphors are broader in comparison with single-doped phosphors and show tunable colors from green to yellow to orange-red when the ratio of Tb(3+) to Eu(3+) is adjusted These results demonstrate that LGBO:Tb(3+), Eu(3+) phosphors have potential use in light-emitting diodes. PMID:26720264

  17. Improvement in the optical quality and energy resolution of CsSrBr3: Eu scintillator crystals

    NASA Astrophysics Data System (ADS)

    Gokhale, Sasmit S.; Stand, Luis; Lindsey, Adam; Koschan, Merry; Zhuravleva, Mariya; Melcher, Charles L.

    2016-07-01

    The crystal growth of CsSrBr3: Eu with improved energy resolution for use in gamma-ray detection applications is reported. CsSrBr3 boules doped with 5% Eu were grown by the vertical Bridgman method in quartz ampoules of 17 mm and 22 mm diameter. It was observed that the addition of an excess of CsBr in the melt improved the optical transparency and energy resolution of the scintillator crystals. The energy resolution of the gamma-ray spectra recorded with crystals measuring ø 22 mm×15 mm was 7.4% at 662 keV (for a crystal with non-optimized stoichiometry) and 6.2% at 662 keV (for a crystal with optimized stoichiometry i.e. excess CsBr in the melt), which is a significant improvement over previous reports. Temperature dependent powder XRD measurements were also carried out to study the solid-solid phase transition which occurs as the crystals are cooled after growth.

  18. Energy transfer and luminescence properties of Ba2CaMoO6:Eu3+ phosphors prepared by sol-gel method

    NASA Astrophysics Data System (ADS)

    Li, Yuntong; Liu, Xiaohua

    2015-04-01

    Novel Ba2CaMoO6:Eu3+ reddish orange phosphors were synthesized by the sol-gel method. The XRD results indicate that the phosphors keep the cubic structure. The excitation spectra exhibit an intense broad charge transfer (CT) band centered at 380 nm, indicating the phosphors can be effectively excited by near UV (370-410 nm) light. The photoluminescence (PL) measurements demonstrate a strong red emission band centered at about 595 nm (5D0 → 7F1) under host excitation at 380 nm. A low concentration quenching occurs in Ba2CaMoO6:Eu3+ and the optimal doping concentration is about 6 mol%. The efficient energy transfer from host to Eu3+ ions in Ba2CaMoO6:Eu3+ phosphors has been discussed in this paper.

  19. Tunable full-color emitting BaMg2Al6Si9O30:Eu2+, Tb3+, Mn2+ phosphors based on energy transfer.

    PubMed

    Lü, Wei; Hao, Zhendong; Zhang, Xia; Luo, Yongshi; Wang, Xiaojun; Zhang, Jiahua

    2011-08-15

    A series of single-phase full-color emitting BaMg(2)Al(6)Si(9)O(30):Eu(2+), Tb(3+), Mn(2+) phosphors has been synthesized by solid-state reaction. Energy transfer from Eu(2+) to Tb(3+) and Eu(2+) to Mn(2+) in BaMg(2)Al(6)Si(9)O(30) host matrix is studied by luminescence spectra and energy-transfer efficiency and lifetimes. The wavelength-tunable white light can be realized by coupling the emission bands centered at 450, 542, and 610 nm ascribed to the contribution from Eu(2+) and Tb(3+) and Mn(2+), respectively. By properly tuning the relative composition of Tb(3+)/Mn(2+), chromaticity coordinates of (0.31, 0.30), high color rendering index R(a) = 90, and correlated color temperature (CCT) = 5374 K can be achieved upon excitation of UV light. Thermal quenching properties reveal that BaMg(2)Al(6)Si(9)O(30): Eu(2+), Tb(3+), Mn(2+) exhibits excellent characteristics even better than that of YAG:Ce. Our results indicate our white BaMg(2)Al(6)Si(9)O(30):Eu(2+), Tb(3+), Mn(2+) can serve as a key material for phosphor-converted light-emitting diode and fluorescent lamps. PMID:21766885

  20. A single-phased tunable emission phosphor MgY2Si3O10: Eu(3+), Bi(3+) with efficient energy transfer for white LEDs.

    PubMed

    Zhou, Hongpeng; Jin, Ye; Jiang, Mingsong; Wang, Qingping; Jiang, Xingxing

    2015-01-21

    A novel single-phased tunable emitting phosphor MgY2Si3O10: Bi(3+), Eu(3+) has been synthesized by a conventional high temperature solid-state method. X-ray diffraction (XRD), photoluminescence emission and excitation spectra were utilized to characterize the as-synthesized samples. Under UV-light pumping, MgY2Si3O10: Bi(3+) showed characteristic blue emission corresponding to the (3)P1→(1)S0 transition of Bi(3+) ions, and MgY2Si3O10: Eu(3+) showed characteristic red emission corresponding to the (5)D0→(7)FJ (J = 1, 2, 3, 4) transition of Eu(3+) ions. Spectra indicate that Bi(3+) ions occupy two nonequivalent sites in the MgY2Si3O10 matrix, namely, Bi(3+)(i) and Bi(3+)(ii). The two sites (Bi(3+)(i) and Bi(3+)(ii)) exhibit broad emission peaks at 411 nm and 490 nm, respectively. Efficient energy transfer between these two Bi(3+) sites has been proven using the spectra. The spectral overlap between the emission spectrum of Bi(3+) and the excitation spectrum of Eu(3+) allows for resonance-type energy transfer to occur from Bi(3+) to Eu(3+). The efficient energy transfer from Bi(3+) to Eu(3+)via a dipole-quadrupole interaction mechanism is significantly demonstrated by comparing experimental data with theoretical calculations. According to the concentration quenching-method, the critical distance of energy transfer from Bi(3+) to Eu(3+) is calculated to be 13.2 Å. As it is a new phosphor, CIE coordinates and CCT temperature, in addition to efficient energy transfer have been also investigated in detail. White light emission for MgY2Si3O10: n Bi(3+), m Eu(3+) can be realized through controlling the concentrations of Bi(3+) and Eu(3+). All of the results indicate that MgY2Si3O10: n Bi(3+), m Eu(3+) is a potential phosphor for white light UV-LEDs. PMID:25409734

  1. White light emission and energy transfer in Dy{sup 3+}/Eu{sup 3+} co-doped BaLa{sub 2}WO{sub 7} phosphors

    SciTech Connect

    Deng, Yaomin; Yi, Shuangping Huang, Jun; Xian, Jieqiang; Zhao, Weiren

    2014-09-15

    Highlights: • BaLa{sub 2}WO{sub 7}:Dy{sup 3+}, Eu{sup 3+} phosphors were synthesized by solid-state reaction. • Eu{sup 3+} compensated the red emission component of the BaLa{sub 2}WO{sub 7}:Dy{sup 3+} phosphor. • The observed emission lifetimes indicates the energy transfer from Dy{sup 3+} to Eu{sup 3+}. • BaLa{sub 2}WO{sub 7}:Dy{sup 3+}, Eu{sup 3+} are potential phosphors used in n-UV pumped white LEDs. - Abstract: Tunable full color emissive BaLa{sub 1.75−x}WO{sub 7}:0.25Dy{sup 3+}, xEu{sup 3+} phosphors which peaked at 484 nm (blue), 572 nm (yellow), 593 nm (orange), and 617 nm (red) were synthesized by the traditional solid-state reaction method. The as-synthesized phosphors were characterized by X-ray power diffraction, diffused reflectance spectra, photoluminescence decay curves, photoluminescence excitation and emission spectra. The photoluminescence excitation spectra range from 200 to 500 nm, including an O{sup 2−}⟶W{sup 6+} charge transfer band and several 4f–4f transition peaks of Dy{sup 3+} and Eu{sup 3+}. Co-doping with Eu{sup 3+} compensated the red emission component of the BaLa{sub 2}WO{sub 7}:Dy{sup 3+} phosphor. Furthermore, the energy transfer from Dy{sup 3+} to Eu{sup 3+} was confirmed based on the luminescence spectra and decay curves. The intense white light emissions are suggestive exploration for the potential phosphor for optical materials applications used in the ultraviolet excited white light emitting diodes.

  2. Luminescence and energy transfer in Eu2+, Mn2+ co-doped Ca2SrNaLa(PO4)3F

    NASA Astrophysics Data System (ADS)

    Shanshan, Hu; Wanjun, Tang

    2013-12-01

    A new compound Ca2SrNaLa(PO4)3F, isotypic with hexagonal Ca(Sr,Na,Ca)(Ca,Sr,Ce)3(PO4)3F, is reported. Its cell parameters have been determined from X-ray powder diffraction data. Crystallization occurs in the hexagonal space group P63 (No. 173) with a = 9.515(1) Å, c = 7.028(1) Å, and Z = 2. Eu2+ and Mn2+ activated Ca2SrNaLa(PO4)3F phosphors have been prepared. The energy transfer of Eu2+ → Mn2+ has been investigated. The resonant type energy transfer from Eu2+ to Mn2+ has been demonstrated, and the energy transfer efficiency has also been calculated according to their PL decay curves. A color-tunable emission in Ca2SrNaLa(PO4)3F phosphors can be realized by Eu2+ → Mn2+ energy transfer. White light can be achieved in a single-phased Ca2SrNaLa(PO4)3F host by co-doping Eu2+ and Mn2+ with CIE (0.32, 0.31). Our results demonstrate that the potential application of these phosphors in solid-state lighting and (or) other areas.

  3. Energy transfer in M₅(PO₄)₃  F:Eu²⁺,Ce³⁺ (M = Ca and Ba) phosphors.

    PubMed

    Shinde, K N; Dhoble, S J

    2014-08-01

    M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphors were successfully prepared by the combustion synthesis method. The introduction of co-dopant (Ce(3+)) into the host enhanced the luminescent intensity of the M5(PO4)3F:Eu(2+) (M = Ca and Ba) efficiently. Previously, we have reported the synthesis and photoluminescence properties of same phosphors. The aim of this article is to report energy transfer mechanism between Ce(3+) ➔Eu(2+) ions in M5(PO4)3F:Eu(2+) (M = Ca and Ba) phosphors, where Ce(3+) ions act as sensitizers and Eu(2+) ions act as activators. The M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphor exhibits great potential for use in white ultraviolet (UV) light-emitting diode applications to serve as a single-phased phosphor that can be pumped with near-UV or UV light-emitting diodes. PMID:23901019

  4. Single-phased white-light-emitting Ca₄(PO₄)₂O:Ce³⁺,Eu²⁺ phosphors based on energy transfer.

    PubMed

    Jia, Yonglei; Pang, Ran; Li, Haifeng; Sun, Wenzhi; Fu, Jipeng; Jiang, Lihong; Zhang, Su; Su, Qiang; Li, Chengyu; Liu, Ru-Shi

    2015-07-01

    A novel single-composition Ca4(PO4)2O:Ce(3+),Eu(2+) phosphor emitting white light was synthesized by conventional solid-state reaction for light-emitting diode applications. X-ray diffraction, photoluminescence spectra, and luminescence decay spectra were used to characterize the samples. Energy transfer from Ce(3+) to Eu(2+) ions was observed in the co-doped samples, and the transfer mechanism in the Ca4(PO4)2O:Ce(3+),Eu(2+) phosphors was dipole-dipole interaction. The emission hue of Ca4(PO4)2O:Ce(3+),Eu(2+) was found to vary from blue (0.165, 0.188) to white (0.332, 0.300) and eventually to orange (0.519, 0.366) by precisely controlling the ratio of Ce(3+) to Eu(2+). The combination of a 380 nm near-ultraviolet chip with a Ca4(PO4)2O:0.02Ce(3+),0.012Eu(2+) phosphor produced a diode emitting white light with ultra-wideband emission and a correlated color temperature of 4124 K. Overall, results indicated that the prepared samples may be potentially applied in white-light-emitting diodes. PMID:26017804

  5. Radiative energy transfer in ZnAl2O4:0.1% Ce3+, x% Eu3+ nanophosphor synthesized by sol-gel process

    NASA Astrophysics Data System (ADS)

    Motloung, S. V.; Dejene, F. B.; Kroon, R. E.; Swart, H. C.; Ntwaeaborwa, O. M.

    2015-07-01

    Zinc aluminate (ZnAl2O4) hosts and 0.1% Ce3+, x% Eu3+ co-activated ZnAl2O4 phosphor were successfully prepared at a relatively low temperature (~80 °C) using the sol-gel method. The co-activator (Eu3+) concentration was varied in the range of 0≤x≤2 mol%, while the 0.1% Ce3+ was kept constant. The X-ray diffraction (XRD) data revealed that all annealed samples consisted of the pure cubic ZnAl2O4 structure. The estimated crystallite size was in the range of 18-21 nm in diameter. The results showed that the full width at half maximum (FWHM) increased with the increase in Eu3+ mol%, which suggested a decrease in particle size. The nanopowder microstructure revealed that the material consisted of non-uniform sizes and the loss of lattice fringes as the Eu3+ concentration was increased suggested the increase in strain or disorder. The photoluminescence (PL) results showed that the host, activated and co-activated nanophosphor emitted at different wavelengths. The peak shifts suggested that the luminescence might originate either from the defects in the host, Ce3+ or Eu3+ ions. The incorporation of the co-activator (Eu3+) at higher concentration resulted in radiative energy transfer from Ce3+→Eu3+. The CIE colour coordinates showed a shift from the blue to orange region as the Eu3+ concentration was increased.

  6. Novel red-emitting Ba2Tb(BO3)2Cl:Eu phosphor with efficient energy transfer for potential application in white light-emitting diodes.

    PubMed

    Xia, Zhiguo; Zhuang, Jiaqing; Liao, Libing

    2012-07-01

    A novel red-emitting Ba(2)Tb(BO(3))(2)Cl:Eu phosphor possessing a broad excitation band in the near-ultraviolet (n-UV) region was synthesized by the solid-state reaction. Versatile Ba(2)Tb(BO(3))(2)Cl compound has a rigid open framework, which can offer two types of sites for various valence's cations to occupy, and the coexistence of Eu(2+)/Eu(3+) and the red-emitting luminescence from Eu(3+) with the aid of efficient energy transfer of Eu(2+)-Eu(3+)(Tb(3+)) and Tb(3+)-Eu(3+) have been investigated. Ba(2)Tb(BO(3))(2)Cl emits green emission with the main peak around 543 nm, which originates from (5)D(4) → (7)F(5) transition of Tb(3+). Ba(2)Tb(BO(3))(2)Cl:Eu shows bright red emission from Eu(3+) with peaks around 594, 612, and 624 nm under n-UV excitation (350-420 nm). The existence of Eu(2+) can be testified by the broad-band excitation spectrum, UV-vis reflectance spectrum, X-ray photoelectron spectrum, and Eu L(3)-edge X-ray absorption spectrum. Decay time and time-resolved luminescence measurements indicated that the interesting luminescence behavior should be ascribed to efficient energy transfer of Eu(2+)-Eu(3+)(Tb(3+)) and Tb(3+)-Eu(3+) in Ba(2)Tb(BO(3))(2)Cl:Eu phosphors. PMID:22686374

  7. Influence of metal surfaces on coking in a reforming/methanation thermochemical transport distributed receiver solar energy system

    SciTech Connect

    Weirick, L.J.; Greenholt, C.J.

    1986-09-01

    A number of thermochemical cycles have been proposed for energy transport. The one under investigation at Sandia National Laboratories Albuquerque involves converting a carbon dioxide/methane mixture to carbon monoxide and hydrogen during the endothermic reforming reaction, and then back again to carbon dioxide and methane during the exothermic methanation reaction. Carbon formation and deposition in either the reformer or the methanator is a serious concern. We performed simultaneous thermogravimetric and gas spectrometric analyses to measure carbon deposition rate and changing gas composition in the presence of material candidates for use in the reforming/methanation loop. We found that nickel-base superalloys such as Inconel 625 are good candidates for the high temperature endothermic reforming reactor, and stainless steels such as 316L will suffice for the low temperature exothermic methanation reactor. We also found that adding carbon dioxide to the carbon monoxide/hydrogen gas mix in an attempt to reduce carbon formation was not effective, particularly at lower temperatures for iron-base alloys. More important to the propensity to form carbon is the ratio of carbon monoxide to hydrogen. 9 figs., 1 tab.

  8. Building state capacity in Russia: A case study of energy sector reform, 1992--1998

    NASA Astrophysics Data System (ADS)

    Kim, Younkyoo

    This study seeks an explanation for the neglect of state building in Russia. The major hypothesis is that dependence on external rent leads to the weakness of the state. Three intervening variables---transaction costs, bargaining power of the state, and discount rates---are posited to explain variance on the dependent variable, the weakness of the state. Based on the exploration of three dimensions of energy sector reform, the dissertation argues that in the short run resource rents may be the only reliable and adequate source of finance for the Russian government. The division of resource rents among the many claimants (state vs. business, state vs. society, Moscow vs. regions, and Russia vs. foreign companies), it submits, will pose a stringent test of the viability of democratic governance in Russia. The dissertation concludes that some evidence indicates that Russia has in fact met the characteristics of the rentier state. The greater reliance on a large resource sector for revenue has led to high transaction costs of tax collection, weak bargaining power of the state, and high discount rates of government officials in Russia.

  9. Support for EU fundraising in the field of Environment & Energy - BayFOR

    NASA Astrophysics Data System (ADS)

    Ammerl, Thomas; Baumann, Cornelia; Reiter, Andrea; Blume, Andreas; Just, Jana; Franke, Jan

    2013-04-01

    The Bavarian Research Alliance (BayFOR, http://www.bayfor.org) is a private company for the support of Bavaria (Free State in the South East of Germany) as a centre for science and innovation within the European Research Area. It was set up on the initiative of the Bavarian universities to strengthen their networking at regional, national and international level while helping them to prepare to meet the requirements for European research funding. The focus is directed at the current EU Framework Programme (FP7) and the forthcoming Framework Programme for Research and Innovation "Horizon 2020", but also comprises the wide range of European programmes (e.g. FP7, LIFE+, Interreg, COST, EUREKA, ERA-Nets, IEE (CIP), LLP, Calls for tender). BayFOR is also a partner institution in the Bavarian "Haus der Forschung" (www.hausderforschung.bayern.de/en). BayFORs overall aim is to strengthen and permanently anchor the science and innovation location of Bavaria in the European Research Area through: a) Initiation of national and in particular European innovation and science partnerships from academia and business b) Improvement of innovation potential of Bavarian universities and SME c) Support in acquisition, management and dissemination of results of European and international projects in the field of research and technological development The service portfolio of the EU Funding Advisory Service reaches from the first project idea to project implementation. The minimum condition for BayFOR support is at least one partner from Bavaria (Germany) must be part of the applying consortium: a) Recommendation of funding programmes/instruments (incl. integration of relevant EU policies & directives) b) Partner search c) Project development and proposal elaboration (Online platform, Creation of consortium, Attendance at meetings, Preparation of documents, Proposal structure elaboration, Provision of templates, Editorial support: Gantt, PERT, Impact, EU added value) d) Support in the

  10. Spectroscopy and energy transfer in lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3)(+)-Eu(3+) ions.

    PubMed

    Pisarska, Joanna; Kos, Agnieszka; Pisarski, Wojciech A

    2014-08-14

    Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4→(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0→(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements. PMID:24824577

  11. Color-tunable photoluminescence and energy transfer properties of single-phase Ba10(PO4)6O:Eu2+, Mn2+ phosphors

    NASA Astrophysics Data System (ADS)

    Guo, Qingfeng; Liao, Libing; Mei, Lefu; Liu, Haikun

    2015-12-01

    Single-phase Ba10-x-y(PO4)6O:xEu2+,yMn2+ samples with apatite structure have been synthesized via a solid-state reaction method. The phase structure, luminescence properties, lifetime, PL thermal stability, as well as fluorescence decay curves of the samples were investigated. Effective energy transfer occurs from Eu2+ to Mn2+ in Ba10(PO4)6O and a possible mechanism of the energy-transfer from Eu2+ to Mn2+ is proposed. The critical distances Rc was calculated by concentration quenching and turned out to be about 0.817 nm (xc=0.21). The CIE and thermally stable luminescence behaviors of Ba9.94(PO4)6O:0.06Eu2+ phosphor were also studied in detail. All the results indicate that Ba10-x-y(PO4)6O:xEu2+, yMn2+ phosphors have potential applications as near UV-convertible phosphors for white light-emitting diodes.

  12. Improved energy of the 21.5 keV M1 + E2 nuclear transition in 151Eu

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh.; Kovalík, A.; Filosofov, D. V.; Ryšavý, M.; Perevoshchikov, L. L.; Baimukhanova, A.

    2016-05-01

    Using internal conversion electron spectroscopy, improved energy 21 541.5±0.5 eV was determined for the 21.5keV M1 + E2 nuclear transition in 151Eu populated in the electron capture decay of 151Gd . This value was found to agree well with the present adopted value but is much more accurate. A value of 0.0305±0.0011 derived for the E2 admixture parameter \\vertδ(E2/M1)\\vert from the measured conversion electron line intensities corresponds to the present adopted value. A possible effect of nuclear structure on the multipolarity of the 21.5 keV transition was also investigated.

  13. Energy transfer and tunable multicolor emission and paramagnetic properties of GdF3:Dy(3+),Tb(3+),Eu(3+) phosphors.

    PubMed

    Guan, Hongxia; Sheng, Ye; Xu, Chengyi; Dai, Yunzhi; Xie, Xiaoming; Zou, Haifeng

    2016-07-20

    A series of Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy(3+), GdF3:Tb(3+) and GdF3:Eu(3+) samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy(3+), Tb(3+) and Tb(3+), Eu(3+) ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy(3+) → Tb(3+) and (2) Tb(3+) → Eu(3+). More significantly, in the Dy(3+), Tb(3+), and Eu(3+) tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu(3+). In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy(3+), Tb(3+), Eu(3+) tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays. PMID:27388285

  14. A System of Systems (SoS) Approach to transforming to a low carbon resource-efficient energy system: Insights for the European Union (EU)

    NASA Astrophysics Data System (ADS)

    Madani, K.; Jess, T.; Mahlooji, M.; Ristic, B.

    2015-12-01

    The world's energy sector is experiencing a serious transition from reliance on fossil fuel energy sources to extensive reliance on renewable energies. Europe is leading the way in this transition to a low carbon economy in an attempt to keep climate change below 2oC. Member States have committed themselves to reducing greenhouse gas emissions by 20% and increasing the share of renewables in the EU's energy mix to 20% by 2020. The EU has now gone a step further with the objective of reducing greenhouse gas emissions by 80-95% by 2050. Nevertheless, the short-term focus of the European Commission is at "cost-efficient ways" to cut its greenhouse gas emissions which forgoes the unintended impacts of a large expansion of low-carbon energy technologies on major natural resources such as water and land. This study uses the "System of Systems (SoS) Approach to Energy Sustainability Assessment" (Hadian and Madani, 2015) to evaluate the Relative Aggregate Footprint (RAF) of energy sources in different European Union (EU) member states. RAF reflects the overall resource-use efficiency of energy sources with respect to four criteria: carbon footprint, water footprint, land footprint, and economic cost. Weights are assigned to the four resource use efficiency criteria based on each member state's varying natural and economic resources to examine the changes in the desirability of energy sources based on regional resource availability conditions, and to help evaluating the overall resource use efficiency of the EU's energy portfolio. A longer-term strategy in Europe has been devised under the "Resource Efficient Europe" flagship imitative intended to put the EU on course to using resources in a sustainable way. This study will highlight the resource efficiency of the EU's energy sector in order to assist in a sustainable transition to a low carbon economy in Europe. ReferenceHadian S, Madani K (2015) A System of Systems Approach to Energy Sustainability Assessment: Are All

  15. A novel orange-yellow-emitting Ba3Lu(PO4)3:Eu2+,Mn2+ phosphor with energy transfer for UV-excited white LEDs.

    PubMed

    Guo, Ning; Huang, Yeju; Jia, Yongchao; Lv, Wenzhen; Zhao, Qi; Lü, Wei; Xia, Zhiguo; You, Hongpeng

    2013-01-28

    Eu(2+)-Mn(2+) codoped orange-yellow-emitting Ba(3)Lu(PO(4))(3) phosphors were synthesized by a solid-state reaction. The synthesis, structure refinement, and luminescence properties of the obtained phosphor were first investigated in detail. The crystal structure was refined with a split-atom model, where the oxygen atoms are distributed over two partially occupied sites. The refinement confirmed that BLuP:0.005Eu(2+),0.06Mn(2+) has a cubic unit cell with space group I43d (no. 220), cell parameters a = b = c = 10.4025 Å and Z = 4. The luminescent properties reveal that the developed phosphor can efficiently convert UV photons in a broad range from 230 to 430 nm into orange-yellow emission. On the basis of the luminescence spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu(2+) to Mn(2+) ions takes place in the codoped Ba(3)Lu(PO(4))(3):Eu(2+),Mn(2+) phosphor, and the energy transfer efficiency increases with an increase in the Mn(2+) content. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis. In particular, our developed phosphor contains a larger amount of the red-emitting component, compared with the commercial YAG:Ce phosphor, possessing favorable properties for application in warm white LEDs with low correlated color temperature. PMID:23108262

  16. State-selective energy transfer from Er3+ to Eu3+ in Bi2O3-GeO2-Ga2O3-Na2O glasses.

    PubMed

    Wang, Jun; Zhou, Yaxun; Dai, Shixun; Xu, Tiefeng; Nie, Qiuhua

    2009-02-01

    The Eu(3+) ion was introduced into Er(3+) doped Bi(2)O(3)-GeO(2)-Ga(2)O(3)-Na(2)O (BGGN) glasses to improve the 1.5 microm band emission. As a function of Eu(2)O(3) doped content, we observed the increase in non-radiative decay rate of Er(3+) not only (4)I(11/2) energy level but also (4)I(13/2) energy level, while the lifetime of Er(3+):(4)I(11/2) and (4)I(13/2) levels were shortened from 607 to 241 micros and from 3.37 to 1.88 ms, respectively. Accordingly, the upconversion fluorescence (green and red) was quenched. The total quantum efficiency of the Er(3+):(4)I(13/2) increased with the Eu(2)O(3) content increasing up to 0.2 mol% due to the state-selective energy transfer from Er(3+) to Eu(3+). PMID:19010716

  17. NETL - Fuel Reforming Facilities

    SciTech Connect

    2013-06-12

    Research using NETL's Fuel Reforming Facilities explores catalytic issues inherent in fossil-energy related applications, including catalyst synthesis and characterization, reaction kinetics, catalyst activity and selectivity, catalyst deactivation, and stability.

  18. NETL - Fuel Reforming Facilities

    ScienceCinema

    None

    2014-06-27

    Research using NETL's Fuel Reforming Facilities explores catalytic issues inherent in fossil-energy related applications, including catalyst synthesis and characterization, reaction kinetics, catalyst activity and selectivity, catalyst deactivation, and stability.

  19. Promoting electricity from renewable energy sources -- lessons learned from the EU, U.S. and Japan

    SciTech Connect

    Haas, Reinhard; Meyer, Niels I.; Held, Anne; Finon, Dominique; Lorenzoni, Arturo; Wiser, Ryan; Nishio, Ken-ichiro

    2007-06-01

    The promotion of electricity generated from Renewable Energy Sources (RES) has recently gained high priority in the energy policy strategies of many countries in response to concerns about global climate change, energy security and other reasons. This chapter compares and contrasts the experience of a number of countries in Europe, states in the US as well as Japan in promoting RES, identifying what appear to be the most successful policy measures. Clearly, a wide range of policy instruments have been tried and are in place in different parts of the world to promote renewable energy technologies. The design and performance of these schemes varies from place to place, requiring further research to determine their effectiveness in delivering the desired results. The main conclusions that can be drawn from the present analysis are: (1) Generally speaking, promotional schemes that are properly designed within a stable framework and offer long-term investment continuity produce better results. Credibility and continuity reduce risks thus leading to lower profit requirements by investors. (2) Despite their significant growth in absolute terms in a number of key markets, the near-term prognosis for renewables is one of modest success if measured in terms of the percentage of the total energy provided by renewables on a world-wide basis. This is a significant challenge, suggesting that renewables have to grow at an even faster pace if we expect them to contribute on a significant scale to the world's energy mix.

  20. Spectroscopic properties and location of the Tb(3+) and Eu(3+) energy levels in Y2O2S under high hydrostatic pressure.

    PubMed

    Behrendt, M; Mahlik, S; Szczodrowski, K; Kukliński, B; Grinberg, M

    2016-08-10

    In this contribution, an extensive spectroscopic study of Y2O2S doped with Eu(3+) and Tb(3+) is presented. Steady-state luminescence and luminescence excitation spectra as well as the time-resolved spectra and luminescence kinetics were obtained at high hydrostatic pressures up to 240 kbar. It was found that pressure quenches the luminescence from the (5)D3 excited state of Tb(3+) and recovers additional luminescence related to transitions from the (5)D3 state of Eu(3+). These effects are related to the pressure-induced increases in the energies of the ground electronic manifold 4f(n) of Eu(3+) and Tb(3+) ions with respect to the band edges. Analysis of the emission and excitation spectra allowed the estimation of the energies of the ground states of all lanthanide (Ln) ions (Ln(3+) and Ln(2+)) with respect to the valence and conduction bands edges of the Y2O2S host. The bandgap energy and difference between energies of the ground states of Ln(2+) and Ln(3+) have been calculated as functions of pressure. The experimental high-pressure spectroscopy results allow the calculation of the absolute values (calculated with respect to the vacuum level) of the energies and pressure-induced shifts of the conduction and valence band edges and the ground states of Ln(3+) and Ln(2+) ions in Y2O2S. PMID:27453544

  1. A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu.

    PubMed

    Ewels, Philip; Sikora, Thierry; Serin, Virginie; Ewels, Chris P; Lajaunie, Luc

    2016-06-01

    The electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra. PMID:26899024

  2. Remote Control Effect of Li+, Na+, K+ Ions on the Super Energy Transfer Process in ZnMoO4:Eu3+, Bi3+ Phosphors

    NASA Astrophysics Data System (ADS)

    Ran, Weiguang; Wang, Lili; Tan, Lingling; Qu, Dan; Shi, Jinsheng

    2016-06-01

    Luminescent properties are affected by lattice environment of luminescence centers. The lattice environment of emission centers can be effectively changed due to the diversity of lattice environment in multiple site structure. But how precisely control the doped ions enter into different sites is still very difficult. Here we proposed an example to demonstrate how to control the doped ions into the target site for the first time. Alkali metal ions doped ZnMoO4:Bi3+, Eu3+ phosphors were prepared by the conventional high temperature solid state reaction method. The influence of alkali metal ions as charge compensators and remote control devices were respectively observed. Li+ and K+ ions occupy the Zn(2) sites, which impede Eu and Bi enter the adjacent Zn(2) sites. However, Na+ ions lie in Zn(1) sites, which greatly promoted the Bi and Eu into the adjacent Zn(2) sites. The Bi3+ and Eu3+ ions which lie in the immediate vicinity Zn(2) sites set off intense exchange interaction due to their short relative distance. This mechanism provides a mode how to use remote control device to enhance the energy transfer efficiency which expected to be used to design efficient luminescent materials.

  3. Remote Control Effect of Li+, Na+, K+ Ions on the Super Energy Transfer Process in ZnMoO4:Eu3+, Bi3+ Phosphors

    PubMed Central

    Ran, Weiguang; Wang, Lili; Tan, Lingling; Qu, Dan; Shi, Jinsheng

    2016-01-01

    Luminescent properties are affected by lattice environment of luminescence centers. The lattice environment of emission centers can be effectively changed due to the diversity of lattice environment in multiple site structure. But how precisely control the doped ions enter into different sites is still very difficult. Here we proposed an example to demonstrate how to control the doped ions into the target site for the first time. Alkali metal ions doped ZnMoO4:Bi3+, Eu3+ phosphors were prepared by the conventional high temperature solid state reaction method. The influence of alkali metal ions as charge compensators and remote control devices were respectively observed. Li+ and K+ ions occupy the Zn(2) sites, which impede Eu and Bi enter the adjacent Zn(2) sites. However, Na+ ions lie in Zn(1) sites, which greatly promoted the Bi and Eu into the adjacent Zn(2) sites. The Bi3+ and Eu3+ ions which lie in the immediate vicinity Zn(2) sites set off intense exchange interaction due to their short relative distance. This mechanism provides a mode how to use remote control device to enhance the energy transfer efficiency which expected to be used to design efficient luminescent materials. PMID:27278286

  4. Remote Control Effect of Li(+), Na(+), K(+) Ions on the Super Energy Transfer Process in ZnMoO4:Eu(3+), Bi(3+) Phosphors.

    PubMed

    Ran, Weiguang; Wang, Lili; Tan, Lingling; Qu, Dan; Shi, Jinsheng

    2016-01-01

    Luminescent properties are affected by lattice environment of luminescence centers. The lattice environment of emission centers can be effectively changed due to the diversity of lattice environment in multiple site structure. But how precisely control the doped ions enter into different sites is still very difficult. Here we proposed an example to demonstrate how to control the doped ions into the target site for the first time. Alkali metal ions doped ZnMoO4:Bi(3+), Eu(3+) phosphors were prepared by the conventional high temperature solid state reaction method. The influence of alkali metal ions as charge compensators and remote control devices were respectively observed. Li(+) and K(+) ions occupy the Zn(2) sites, which impede Eu and Bi enter the adjacent Zn(2) sites. However, Na(+) ions lie in Zn(1) sites, which greatly promoted the Bi and Eu into the adjacent Zn(2) sites. The Bi(3+) and Eu(3+) ions which lie in the immediate vicinity Zn(2) sites set off intense exchange interaction due to their short relative distance. This mechanism provides a mode how to use remote control device to enhance the energy transfer efficiency which expected to be used to design efficient luminescent materials. PMID:27278286

  5. Manifestation of π-π stacking interactions in luminescence properties and energy transfer in aromatically-derived Tb, Eu and Gd tris(pyrazolyl)borate complexes.

    PubMed

    Mikhalyova, Elena A; Yakovenko, Anastasiya V; Zeller, Matthias; Kiskin, Mikhail A; Kolomzarov, Yuriy V; Eremenko, Igor L; Addison, Anthony W; Pavlishchuk, Vitaly V

    2015-04-01

    The three new complexes Tp(Py)Ln(CH3CO2)2(H2O) (Ln = Eu (1), Gd(2), or Tb (3)) were prepared and characterized crystallographically. In the crystal lattices of these complexes, separate molecules are connected in infinite chains by π-stacking interactions. Complexes 1 and 3 display intense photoluminescence and triboluminescence (red and green respectively), while compound 3 exhibits electroluminescence commencing at 9 V in an ITO/PVK/3/Al device (ITO = indium-tin oxide, PVK = poly(N-vinylcarbazole)). A series of Eu/Tb-doped Gd compounds was prepared by cocrystallization from mixtures of 1 and 2 or 2 and 3, respectively. It was shown that π-stacking interactions are involved in increasing the efficiency of energy transfer from the gadolinium complex to emitting [Tp(Py)Eu](2+) or [Tp(Py)Tb](2+) centers, and this energy transfer occurs through hundreds of molecules, resembling the process of energy harvesting in chloroplast stacks. PMID:25797500

  6. Revelation of the Technological Versatility of the Eu(TTA)3Phen Complex by Demonstrating Energy Harvesting, Ultraviolet Light Detection, Temperature Sensing, and Laser Applications.

    PubMed

    Shahi, Praveen Kumar; Singh, Akhilesh Kumar; Singh, Sunil Kumar; Rai, Shyam Bahadur; Ullrich, Bruno

    2015-08-26

    We synthesized the Eu(TTA)3Phen complex and present herein a detailed study of its photophysics. The investigations encompass samples dispersed in poly(vinyl alcohol) and in ethanol in order to explore the versatile applicability of these lanthanide-based materials. Details upon the interaction between Eu, TTA, and the Phen ligands are revealed by Fourier transform infrared and UV-visible absorption, complemented by steady state and temporally resolved emission studies, which provide evidence of an efficient energy transfer from the organic ligands to the central Eu(3+) ion. The material produces efficient emission even under sunlight exposure, a feature pointing toward suitability for luminescent solar concentrators and UV light sensing, which is demonstrated for intensities as low as 200 nW/cm(2). The paper further promotes the complex's capability to be used as luminescence-based temperature sensor demonstrated by the considerable emission intensity changes of ∼4.0% per K in the temperature range of 50-305 K and ∼7% per K in the temeperature range 305-340 K. Finally, increasing the optical excitation causes both spontaneous emission amplification and emission peak narrowing in the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) - features indicative of stimulated emission. These findings in conjunction with the fairly large stimulated emission cross-section of 4.29 × 10(-20) cm(2) demonstrate that the Eu(TTA)3Phen complex dispersed in poly(vinyl alcohol) could be a very promising material choice for lanthanide-polymer based laser architectures. PMID:26238311

  7. Luminescent properties and energy transfer process of Sm3+-Eu3+ co-doped MY2(MoO4)4 (M=Ca, Sr and Ba) red-emitting phosphors

    NASA Astrophysics Data System (ADS)

    Ye, Menglin; Zhou, Gaojian; Zhou, Liqun; Lu, Di; Li, Yue; Xiong, Xing; Yang, Kunzhou; Chen, Menghuan; Pan, Yaxi; Wu, Peng; Wang, Zheng; Liu, Hongying; Xia, Qinghua

    2016-09-01

    MY2(MoO4)4:Sm3+ and MY2(MoO4)4:xSm3+,yEu3+ (M=Ca, Sr and Ba) phosphors were successfully prepared using solid-state reaction route, and their luminescent properties and energy transfer process from Sm3+ to Eu3+ were systematically investigated. The results indicate that MY2(MoO4)4:Sm3+ phosphors can be effectively excited by 407 nm near UV light originating from the 6H5/2 → 4F7/2 transition of Sm3+, and exhibit a satisfactory red emission at 646 nm attributed to the 4G5/2 → 6H9/2 transition of Sm3+, in which the emission intensity of SrY2(MoO4)4:Sm3+ is the strongest among the MY2(MoO4)4:Sm3+ (M=Ca, Sr and Ba) phosphors. For Eu3+ co-doped MY2(MoO4)4:Sm3+ samples, with increasing Eu3+ doping content, the main emission peaks of Sm3+ (approximately 646 nm) are decreased, but the emission peaks and intensity of Eu3+ are increased while the maximum intensity of luminescence at the Eu3+ concentration 0.9. The introduction of Eu3+ in the MY2(MoO4)4:Sm3+ phosphors can remarkably generate a strong emission line at 616 nm, originating from the 5D0→7F2 transition of Eu3+ and Sm3+ (4G5/2) → Eu3+ (5D0) effective energy transfer process. The energy transfer mechanism from Sm3+ to Eu3+ was discussed in detail.

  8. Strong Energy-Transfer-Induced Enhancement of Luminescence Efficiency of Eu(2+)- and Mn(2+)-Codoped Gamma-AlON for Near-UV-LED-Pumped Solid State Lighting.

    PubMed

    Liu, Lihong; Wang, Le; Zhang, Chenning; Cho, Yujin; Dierre, Benjamin; Hirosaki, Naoto; Sekiguchi, Takashi; Xie, Rong-Jun

    2015-06-01

    A series of Eu(2+)- and Mn(2+)-codoped γ-AlON (Al1.7O2.1N0.3) phosphors was synthesized at 1800 °C under 0.5 MPa N2 by using the gas-pressure sintering method (GPS). Eu(2+) and Mn(2+) ions were proved to enter into γ-AlON host lattice by means of XRD, CL, and EDS measurements. Under 365 nm excitation, two emission peaks located at 472 and 517 nm, resulting from 4f(6)5d(1) → 4f(7) and (4)T1(4G) → (6)A1 electron transitions of Eu(2+) and Mn(2+), respectively, can be observed. Energy transfer from Eu(2+) to Mn(2+) was evidenced by directly observing appreciable overlap between the excitation spectrum of Mn(2+) and the emission spectrum of Eu(2+) as well as by the decreased decay time of Eu(2+) with increasing Mn(2+) concentration. The critical energy-transfer distance between Eu(2+) and Mn(2+) and the energy-transfer efficiency were also calculated. The mechanism of energy transfer was identified as a resonant type via a dipole-dipole mechanism. The external quantum efficiency was increased 7 times (from 7% for γ-AlON:Mn(2+) to 49% for γ-AlON:Mn(2+),Eu(2+) under 365 nm excitation), and color-tunable emissions from blue-green to green-yellow were also realized with the Eu(2+) → Mn(2+) energy transfer in γ-AlON. PMID:25993116

  9. [Study on concentration quenching and energy transfer in Ln3+ (Ln = Tb, Tm, Eu) in Y2O3 nanocrystal powders].

    PubMed

    Meng, Qing-Yu; Chen, Bao-Jiu; Xu, Wu; Zhao, Xiao-Xia; Yang, Yan-Min; Di, Wei-Hua; Wang, Xiao-Jun

    2009-01-01

    Nano-powders Y2O3 with various particle sizes and different doping concentrations of Ln (Ln = Tb, Tm, Eu) were prepared by using a combustion technique. The bulky powders doped with concentrations corresponding to nano-powders were obtained by annealing the nano-powders at high temperature. The emission spectra, XRD spectra and TEM were used in the present study. The concentration quenching of luminescent centers and energy transfer between luminescent centers in Y2O3 : Ln nanocrystal powders were investigated. It was found that the behaviors of luminescence concentration quenching for 5D4 --> 7F5 : Tb3+ and 5D0 --> 7F2 : Eu3+ in nano-powders are similar to that in bulky powders. On the contrary, the quenching concentrations for 5D3 --> 7F5 : Tb3+ and 1D2 --> 3H4 : Tm3+ are distinctly higher than that in bulk powders. This owes to the size confinement effect: the interface of nanocrystal particles can stop a portion of the energy transfer, which happens in the bulk ones, between luminescent centers. The size confinement effect can bring different influences to the different types of energy transfer. For instance, it will restrain the energy transfer (governed by electric dipole-dipole interaction) between the ions in long distances, and will hardly affect the energy transfer (governed by exchange interaction) between the ions locating at near intervals. PMID:19385227

  10. Tunable blue-green-emitting Ba3LaNa(PO4)3F:Eu2+,Tb3+ phosphor with energy transfer for near-UV white LEDs.

    PubMed

    Jiao, Mengmeng; Guo, Ning; Lü, Wei; Jia, Yongchao; Lv, Wenzhen; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2013-09-16

    A series of Eu(2+) and Eu(2+)/Tb(3+) activated novel Ba3LaNa(PO4)3F phosphors have been synthesized by traditional solid state reaction. Rietveld structure refinement of the obtained phosphor indicates that the Ba3LaNa(PO4)3F host contains three kinds of Ba sites. The photoluminescence properties exhibit that the obtained phosphors can be efficiently excited in the range from 320 to 430 nm, which matches perfectly with the commercial n-UV LED chips. The critical distance of the Eu(2+) ions in Ba3LaNa(PO4)3F:Eu(2+) is calculated and the energy quenching mechanism is proven to be dipole-dipole interaction. Tunable blue-green emitting Ba3LaNa(PO4)3F:Eu(2+),Tb(3+) phosphor has been obtained by co-doping Eu(2+) and Tb(3+) ions into the host and varying their relative ratios. Compared with the Tb(3+) singly doped phosphor, the codoped phosphors have more intense absorption in the n-UV range and stronger emission of the Tb(3+) ions, which are attributed to the effective energy transfer from the Eu(2+) to Tb(3+) ions. The energy transfer from the Eu(2+) to Tb(3+) ions is demonstrated to be a dipole-quadrupole mechanism by the Inokuti-Hirayama (I-H) model. The Eu(2+) and Tb(3+) activated phosphor may be good candidates for blue-green components in n-UV white LEDs. PMID:23992135

  11. Thermoluminescence response of K2Ca2(SO4)3 nanophosphor Co-doped with Eu and Ce for gamma ray dosimetry

    NASA Astrophysics Data System (ADS)

    Patil, B. J.; Bhadane, Mahesh S.; Mandlik, N. T.; Dahiwale, S. S.; Kulkarni, M. S.; Bhatt, B. C.; Bhoraskar, V. N.; Dhole, S. D.

    2015-06-01

    K2Ca2(SO4)3 nanophosphors co-doped with Eu and Ce were synthesized by the chemical co-precipitation method. These samples were further annealed at 700 °C structural reformation. The structural and morphological characteristics were studied using XRD and TEM techniques. The particle size calculated from XRD spectra was around 35 nm. The as synthesized sample shows cubic structure annealed at 700 °C. The as synthesized and annealed sample of K2Ca2(SO4)3: EuCe were irradiated with Co60 gamma rays for the doses from 2Gy to 1kGy. The TL characteristic sample of co-doped were studied for the dosimetric application by gamma radiation. The TL spectrum of annealed sample has single peaked at 160 °C. The Eu doped sample has a high TL sensitivity than Ce doped sample. But after co-doping with Eu and Ce, TL intensity observed to be decreased. The decrees in TL peak intensity of the phosphor on co-doping of Eu and Ce gives an insight into the emission mechanism of the phosphor which involves energy transfer from Eu to Ce. The TL response of all the samples were found to be linear for the dose from 2 Gy to 1 KGy. Therefore, K2Ca2(SO4)3: EuCe nanophosphor can be used for the measurement of high dose of gamma radiation.

  12. Solid oxide fuel cell steam reforming power system

    DOEpatents

    Chick, Lawrence A.; Sprenkle, Vincent L.; Powell, Michael R.; Meinhardt, Kerry D.; Whyatt, Greg A.

    2013-03-12

    The present invention is a Solid Oxide Fuel Cell Reforming Power System that utilizes adiabatic reforming of reformate within this system. By utilizing adiabatic reforming of reformate within the system the system operates at a significantly higher efficiency than other Solid Oxide Reforming Power Systems that exist in the prior art. This is because energy is not lost while materials are cooled and reheated, instead the device operates at a higher temperature. This allows efficiencies higher than 65%.

  13. The Coalition's Higher Education Reforms in England

    ERIC Educational Resources Information Center

    Hillman, Nicholas

    2016-01-01

    The Coalition Government of Conservatives and Liberal Democrats in office from 2010 until 2015 sharply increased the maximum tuition fees for UK and EU undergraduates at English universities to £9,000. Although this is often portrayed as a radical change, it is argued that the reform was an evolution rather than a revolution. Common pessimistic…

  14. Color-tunable properties and energy transfer in Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphor pumped for n-UV w-LEDs

    NASA Astrophysics Data System (ADS)

    Zeng, Chao; Liu, Haikun; Hu, Yingmo; Liao, Libing; Mei, Lefu

    2015-11-01

    A series of Eu2+ and Eu2+/Tb3+ co-doped Ba3GdNa(PO4)3F phosphors have been synthesized via a high temperature solid-state reaction. The relative intensity of PL spectra of Ba3GdNa(PO4)3F:xEu2+ increases with increasing x value, and reaches a maximum at x=0.04. Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors exhibit a broad excitation band ranging from 220 to 450 nm, which matches perfectly with the characteristic emission of n-UV light-emitting diode (LED) chips. Upon 365 nm excitation, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphors show two dominating bands peaked at 466 and 543 nm, which are assigned to the 4f7→4f65d1 transition of the Eu2+ ions and the 5D4→7F5 transition of the Tb3+ ions, respectively. In view of the energy transfer mechanism between Eu2+ and Tb3+, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ emission color can adjust from blue to green, and their chromatic coordinates (x, y) vary from (0.16, 0.135) to (0.254, 0.398). The critical distance was also calculated to be 16.90 Å. The above results indicate that the Ba3GdNa(PO4)3F: Eu2+, Tb3+ phosphors are a candidate for blue-green components in the application of n-UV w-LEDs.

  15. Tax reform and energy in the Philippines economy: A general equilibrium computation

    SciTech Connect

    Boyd, R.G.; Doroodian, K.; Udomvaech, P.

    1994-12-31

    This paper examines how energy tax cuts, offset with income tax increases, affect production, consumption, and total welfare in the Philippines economy. Our results show that energy tax cuts expand the energy and nonmetal mining sectors, but decrease output in the manufacturing, agricultural, and metal mining sectors. Consumption of all goods and services combined increases as the amount of energy tax reduction increases. Our welfare results, however, are mixed. While the welfare of the mid- and high-income levels increases, that of the lowest income level decreases. These results are robust with respect to changes in the elasticity of substitution in energy production as well as the elasticity of substitution in consumer demand. From the standpoint of economic efficiency, a policy such as this would enhance growth and aggregate income. From an equity standpoint, however, this policy is highly regressive in spite of the fact that the richest households pay proportionately more to finance the energy tax reduction. 18 refs., 10 tabs.

  16. Synthesis and tunable luminescent properties of Eu-doped Ca2NaSiO4F - Coexistence of the Eu2+ and Eu3+ centers

    NASA Astrophysics Data System (ADS)

    Xie, Mubiao; Li, Dongyu; Zhu, Guoxian; Pan, Rongkai; Fu, Xionghui

    Novel phosphors Ca2NaSiO4F:Eu were synthesized successfully by the conventional solid-state method in CO atmosphere, and their spectroscopic properties in UV-vis region were investigated. The photoluminescence properties show that Eu3+ ions were partially reduced to Eu2+ in Ca2NaSiO4F. As a result of radiation and re-absorption energy transfer from Eu2+ to Eu3+, both Eu2+ bluish-green emission at around 520 nm and Eu3+ red emission are observed in the emission spectra under the n-UV light excitation. Furthermore, the ratio between Eu2+ and Eu3+ emissions varies with increasing content of overall Eu. Because relative intensity of the red component from Eu3+ became systematically stronger, white light emission can be realized by combining the emission of Eu2+ and Eu3+ in a single host lattice under n-UV light excitation. These results indicate that the Ca2NaSiO4F:Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

  17. Energy transport in photoexcited crystals of K3[Tb(C2O4)3(H2O)].2H2O: Transfer from Tb3+ to Nd3+ and Eu3+

    NASA Astrophysics Data System (ADS)

    Kahwa, Ishenkumba A.; Parkes, Charmaine C.; McPherson, Gary L.

    1995-10-01

    The luminescence decay dynamics of Tb3+(5D4) and Eu(5D0) in triclinic (P1¯) crystalline K3[Ln(C2O4)3(H2O)].2H2O solids was studied between 10 and 298 K in order to establish the energy-transport characteristics. The luminescence decay rate of Tb3+ (740 s-1 for Ln=Tb3+) is temperature independent for the pure terbium complex; with introduction of Ln3+ dopants (e.g., Ln=Nd, Eu) faster decay rates which are temperature dependent are obtained. For the Eu3+ dopant, excitation buildup on the Eu3+(5D0) decay curve upon Tb3+(5D4) excitation confirms that energy transfer from Tb3+(5D4) to Ln3+ is active. The temperature dependence of the energy-transfer process in the K3[Eu0.83Tb0.17(C2O4)3(H2O)].2H2O mixed complex is well described by a relatively simple empirical expression based on Boltzmann's statistical dynamics of Eu3+ electronic energy among the 7FJ (J=0,1,2) terms. The limiting Eu3+-Tb3+ transfer rates are ~5.4×103 and 5.3×104 s-1 at 77 and 298 K, respectively. Energy migration on the terbium sublattice was confirmed by comparing Huber's [Phys. Rev. B 20, 2707 (1979)] trapping functions for K3[Eu0.4Tb0.6(C2O4)3(H2O)].2H2O and K3[Eu0.4Tb0.1Gd0.5(C2O4)3(H2O)].2H2O (Gd3+ serving as a scatterer for Tb3+ excitation). Although the structure of the complexes features a one-dimensional zigzag array of Ln3+ ions, energy transport is diffusive and not one dimensional.

  18. Slab reformer

    NASA Technical Reports Server (NTRS)

    Spurrier, Francis R. (Inventor); DeZubay, Egon A. (Inventor); Murray, Alexander P. (Inventor); Vidt, Edward J. (Inventor)

    1984-01-01

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  19. Slab reformer

    DOEpatents

    Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

    1984-02-07

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  20. Slab reformer

    DOEpatents

    Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

    1985-03-12

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  1. Investigation of ion induced damage in KBr, YAG:Ce, CaF2:Eu and CsI:Tl irradiated by various-energy protons

    NASA Astrophysics Data System (ADS)

    Lin, L. Y.; Leitner, D.; Benatti, C.; Perdikakis, G.; Krause, S. W.; Rencsok, R.; Nash, S.; Wittmer, W.

    2015-03-01

    New experimental results on the scintillation processes for KBr, YAG:Ce, CaF2:Eu and CsI:Tl crystals under H2+ irradiation for the energy range of 600-2150 keV/u are systematically reported. The scintillation light yield was measured as a function of accumulated particle fluence at the rare isotope ReAccelerator (ReA) facility of the National Superconducting Cyclotron Laboratory (NSCL). The data indicates that YAG:Ce and CsI:Tl can maintain stable luminescence under continuous ion bombardment for at least a total fluence of 1.8×1012 ions/mm2 in the energy range used for this experiment. On the other hand, the luminescence of CaF2:Eu shows a rapid initial decay but then maintains a nearly constant luminescence yield. The extraordinary scintillation response of KBr is initially enhanced under ion bombardment, approaches a maximum, and then eventually decays. The scintillation efficiency of the CsI:Tl scintillator is superior to the other materials. The stability of the measured beam profile width deducted from the different scintillator materials in static beam conditions was also investigated as a function of irradiation time. We observed that the low-energy H2+ bombardment (25 keV/u) on the YAG:Ce scintillator can lead to the significant degradation of the scintillation yields. Different scintillation degradation responses for the low- and high-energy bombardments can be attributed to the transmission loss of the emitted light inside the crystal caused by displacement damages.

  2. Luminescence and energy-transfer properties of color-tunable Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) /Eu(2+) /Tb(3+) phosphors for ultraviolet light-emitting diodes.

    PubMed

    Yuan, Bo; Song, Yanhua; Sheng, Ye; Zheng, Keyan; Huo, Qisheng; Xu, Xuechun; Zou, Haifeng

    2016-03-01

    A series of Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) /Eu(2+) /Tb(3+) phosphors was been prepared via a conventional high temperature solid-state reaction and their luminescence properties were studied. The emission spectra of Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Eu(2+) and Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Tb(3+) phosphors show not only a band due to Ce(3+) ions (409 nm) but also as a band due to Eu(2+) (520 nm) and Tb(3+) (542 nm) ions. More importantly, the effective energy transfer from Ce(3+) to Eu(2+) and Tb(3+) ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole-dipole (Ce(3+) to Eu(2+) ) and dipole-quadrupole (Ce(3+) to Tb(3+) ) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce(3+) and Eu(2+) ions as well as Ce(3+) and Tb(3+) ions. The above results indicate that Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Eu(2+) /Tb(3+) are promising single-phase blue-to-green phosphors for application in phosphor conversion white-light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26249728

  3. Luminescence Properties of Pigment-Coated Y2O3:Eu Red Phosphor with α-Fe2O3 by Different Coating Methods and Various Exciting Energy Source

    NASA Astrophysics Data System (ADS)

    Kim, Bong-Chul; Lee, Chun-Yeob; Song, Yoon-Ho; Kang, Seung-Youl; Suh, Kyung-Soo; Lee, Jin Hoo; Lee, Nam-Yang; Kim, Dong-Kuk; Park, Lee-Soon; Lee, Byung-Kyo

    2002-04-01

    Eu3+-doped Y2O3 red phosphor ‘was prepared in order to study the relationship between variation of Eu3+ content and an excitation source such as low and high voltage energy and a vacuum ultraviolet (147 nm). The luminescence properties of pigment-coated Y2O3:Eu by various coating methods and different energy sources were also investigated. Excitation under a vacuum ultraviolet (VUV) for the red phosphor with different amounts of Eu3+ activator exhibited similar luminescence property with the case of being excited by electrons accelerated under low voltage conditions. The surface of Y2O3:Eu red phosphor was treated with α-Fe2O3 pigment by two different methods to improve color purity. One was the adsorption utilizing α-Fe2O3 submicron-particles on the phosphor and the other was a precipitation method utilizing Fe(NO3)3-urea or -hexamethylenetetramine (HMTA). The red phosphor treated with an increasing amount of α-Fe2O3 showed decreasing luminescent intensity, but the color purity improved. The luminescent properties of phosphor treated with α-Fe2O3 pigment by the adsorption method exhibited much less dependency on the applied energy source. Surface treatment by the precipitation method, however, resulted in much a faster decrease of luminescent intensity with a lowering of the applied voltage and VUV region because of a more homogeneous coating of α-Fe2O3 pigment on the phosphor.

  4. Fluidized Bed Steam Reforming (FBSR) Mineralization for High Organic and Nitrate Waste Streams for the Global Nuclear Energy Partnership (GNEP)

    SciTech Connect

    Jantzen, C.M.; Williams, M.R.

    2008-07-01

    Waste streams that may be generated by the Global Nuclear Energy Partnership (GNEP) Advanced Energy Initiative may contain significant quantities of organics (0-53 wt%) and/or nitrates (0-56 wt%). Decomposition of high nitrate streams requires reducing conditions, e.g. organic additives such as sugar or coal, to reduce the NOx in the off-gas to N{sub 2} to meet the Clean Air Act (CAA) standards during processing. Thus, organics will be present during waste form stabilization regardless of which GNEP processes are chosen, e.g. organics in the feed or organics for nitrate destruction. High organic containing wastes cannot be stabilized with the existing HLW Best Developed Available Technology (BDAT) which is HLW vitrification (HLVIT) unless the organics are removed by preprocessing. Alternative waste stabilization processes such as Fluidized Bed Steam Reforming (FBSR) operate at moderate temperatures (650-750 deg. C) compared to vitrification (1150-1300 deg. C). FBSR converts organics to CAA compliant gases, creates no secondary liquid waste streams, and creates a stable mineral waste form that is as durable as glass. For application to the high Cs-137 and Sr-90 containing GNEP waste streams a single phase mineralized Cs-mica phase was made by co-reacting illite clay and GNEP simulated waste. The Cs-mica accommodates up to 30% wt% Cs{sub 2}O and all the GNEP waste species, Ba, Sr, Rb including the Cs-137 transmutation to Ba-137. For reference, the cesium mineral pollucite (CsAlSi{sub 2}O{sub 6}), currently being studied for GNEP applications, can only be fabricated at {>=}1000 deg. C. Pollucite mineralization creates secondary aqueous waste streams and NOx. Pollucite is not tolerant of high concentrations of Ba, Sr or Rb and forces the divalent species into different mineral host phases. The pollucite can accommodate up to 33% wt% Cs{sub 2}O. (authors)

  5. FLUIDIZED BED STEAM REFORMING MINERALIZATION FOR HIGH ORGANIC AND NITRATE WASTE STREAMS FOR THE GLOBAL NUCLEAR ENERGY PARTNERSHIP

    SciTech Connect

    Jantzen, C; Michael Williams, M

    2008-01-11

    Waste streams that may be generated by the Global Nuclear Energy Partnership (GNEP) Advanced Energy Initiative may contain significant quantities of organics (0-53 wt%) and/or nitrates (0-56 wt%). Decomposition of high nitrate streams requires reducing conditions, e.g. organic additives such as sugar or coal, to reduce the NO{sub x} in the off-gas to N{sub 2} to meet the Clean Air Act (CAA) standards during processing. Thus, organics will be present during waste form stabilization regardless of which GNEP processes are chosen, e.g. organics in the feed or organics for nitrate destruction. High organic containing wastes cannot be stabilized with the existing HLW Best Developed Available Technology (BDAT) which is HLW vitrification (HLVIT) unless the organics are removed by preprocessing. Alternative waste stabilization processes such as Fluidized Bed Steam Reforming (FBSR) operate at moderate temperatures (650-750 C) compared to vitrification (1150-1300 C). FBSR converts organics to CAA compliant gases, creates no secondary liquid waste streams, and creates a stable mineral waste form that is as durable as glass. For application to the high Cs-137 and Sr-90 containing GNEP waste streams a single phase mineralized Cs-mica phase was made by co-reacting illite clay and GNEP simulated waste. The Cs-mica accommodates up to 30% wt% Cs{sub 2}O and all the GNEP waste species, Ba, Sr, Rb including the Cs-137 transmutation to Ba-137. For reference, the cesium mineral pollucite (CsAlSi{sub 2}O{sub 6}), currently being studied for GNEP applications, can only be fabricated at {ge} 1000 C. Pollucite mineralization creates secondary aqueous waste streams and NO{sub x}. Pollucite is not tolerant of high concentrations of Ba, Sr or Rb and forces the divalent species into different mineral host phases. The pollucite can accommodate up to 33% wt% Cs{sub 2}O.

  6. What Reform?

    ERIC Educational Resources Information Center

    Welsh, Patrick

    1986-01-01

    A teacher explores the recent educational reform movement and discusses the studies of schools done by Sociologist Christopher Jencks in the 1970s. An important idea that can be extrapolated from Jencks' studies is that schools should function more like families than factories. This would empower teachers and make schooling more equitable,…

  7. Rethinking Reform

    ERIC Educational Resources Information Center

    Garland, James C.

    2010-01-01

    As president of Miami University of Ohio from 1996 until 2006, James C. Garland redefined the public institution as a "semi-private" university by implementing the same tuition for both in-state and out-of-state students. Students from Ohio with need received large scholarships--but those who could afford to pay more did so. The reform, which…

  8. Toothless Reform?

    ERIC Educational Resources Information Center

    Smarick, Andy

    2010-01-01

    To many education reformers, the passage of the federal government's massive stimulus plan, the American Recovery and Reinvestment Act (ARRA), appeared to be a final bright star falling into alignment. The ARRA seemed to complete the constellation: an astounding $100 billion of new federal funds--nearly twice the annual budget of the U.S.…

  9. Efficient energy transfer from inserted CdTe quantum dots to YVO₄:Eu³⁺ inverse opals: a novel strategy to improve and expand visible excitation of rare earth ions.

    PubMed

    Zhu, Yongsheng; Cui, Shaobo; Chen, Xu; Xu, Wen; Zhou, Pingwei; Wang, Yunfeng; Xu, Lin; Song, Hongwei; Huang, Ling; Huang, Wei

    2014-07-21

    Rare earth (RE)-based phosphors demonstrate sharp emission lines, long lifetimes and high luminescence quantum yields; thus, they have been employed in various photoelectric devices, such as light-emitting diodes (LEDs) and solar spectral converters. However, their applications are largely confined by their narrow excitation bands and small absorption cross sections of 4f-4f transitions. In this paper, we demonstrate a novel strategy to improve and expand the visible excitation bands of Eu(3+) ions through the interface energy transfer (ET) from CdTe quantum dots (QDs) to YVO₄:Eu(3+) inverse opal photonic crystals (IOPCs). The significant effects observed in the CdTe QDs/YVO₄:Eu(3+) IOPCs composites were that the excitation of Eu(3+) ions was continuously extended from 450 to 590 nm and that the emission intensity of the (5)D₀-(7)FJ transitions was enhanced ∼20-fold, corresponding to the intrinsic (7)F₁-(5)D₁ excitation at 538 nm. Furthermore, in the IOPC network, the ET efficiency from the QDs to YVO₄:Eu(3+) was greatly improved because of the suppression of energy migration among the CdTe QDs, which gave an optimum ET efficiency as high as 47%. Besides, the modulation of photonic stop bands (PSBs) on the radiative transition rates of the QDs and Eu(3+) ions was studied, which showed that the decay lifetime constants for Eu(3+) ions were independent of PSBs, while those of QDs demonstrated a suppression in the PSBs. Their physical nature was explained theoretically. PMID:24913251

  10. Efficient energy transfer from inserted CdTe quantum dots to YVO4:Eu3+ inverse opals: a novel strategy to improve and expand visible excitation of rare earth ions

    NASA Astrophysics Data System (ADS)

    Zhu, Yongsheng; Cui, Shaobo; Chen, Xu; Xu, Wen; Zhou, Pingwei; Wang, Yunfeng; Xu, Lin; Song, Hongwei; Huang, Ling; Huang, Wei

    2014-06-01

    Rare earth (RE)-based phosphors demonstrate sharp emission lines, long lifetimes and high luminescence quantum yields; thus, they have been employed in various photoelectric devices, such as light-emitting diodes (LEDs) and solar spectral converters. However, their applications are largely confined by their narrow excitation bands and small absorption cross sections of 4f-4f transitions. In this paper, we demonstrate a novel strategy to improve and expand the visible excitation bands of Eu3+ ions through the interface energy transfer (ET) from CdTe quantum dots (QDs) to YVO4:Eu3+ inverse opal photonic crystals (IOPCs). The significant effects observed in the CdTe QDs/YVO4:Eu3+ IOPCs composites were that the excitation of Eu3+ ions was continuously extended from 450 to 590 nm and that the emission intensity of the 5D0-7FJ transitions was enhanced ~20-fold, corresponding to the intrinsic 7F1-5D1 excitation at 538 nm. Furthermore, in the IOPC network, the ET efficiency from the QDs to YVO4:Eu3+ was greatly improved because of the suppression of energy migration among the CdTe QDs, which gave an optimum ET efficiency as high as 47%. Besides, the modulation of photonic stop bands (PSBs) on the radiative transition rates of the QDs and Eu3+ ions was studied, which showed that the decay lifetime constants for Eu3+ ions were independent of PSBs, while those of QDs demonstrated a suppression in the PSBs. Their physical nature was explained theoretically.

  11. Modern money theory and ecological tax reform: A functional finance approach to energy conservation

    NASA Astrophysics Data System (ADS)

    McConnell, Scott L. B.

    This dissertation contributes to heterodox economics by developing a theoretical and policy-relevant link that will promote the conservation of energy while driving the value of the domestic currency. The analysis relies upon the theoretical foundation of modern money theory and functional finance, which states that "taxes-drive-money" where the value of a sovereign nation's currency is imputed through the acceptance by the sovereign nation of the currency in payment of taxation. This theoretical perspective lends itself to various public policy prescriptions, such as government employment policies or the employer of last resort (ELR), which has been discussed at length elsewhere (Wray 1998; Tcherneva 2007, Forstater 2003). This research contributes to this overall program by arguing that the basis for taxation under modern money theory allows public policy makers various alternatives regarding the make-up of the tax system in place. In particular, following functional finance, taxes do not have the sole purpose of paying for government spending, but rather drive the value of the currency and may be designed to perform other functions as well, such as penalizing socially undesirable behavior. The focus in this dissertation is on the amelioration of pollution and increasing energy conservation. The research question for this dissertation is this: what federally implemented tax would best serve the multiple criteria of 1) driving the value of the currency, 2) promoting energy conservation and 3) ameliorating income and wealth disparities inherent in a monetary production economy? This dissertation provides a suggestion for such a tax that would be part of a much larger overall policy program based upon the tenets of modern money theory and functional finance. Additionally, this research seeks to provide an important theoretical contribution to the emerging Post Keynesian and ecological economics dialog.

  12. Regulatory Reform to Promote Clean Energy: The Potential of Output-Based Emissions Standards

    SciTech Connect

    Cox, Matthew; Brown, Dr. Marilyn Ann; Jackson, Roderick K

    2011-01-01

    Barriers to industrial energy-efficient technologies hinder their use. A number of EPA analyses and industrial experts have found that the utilization of input-based emissions standards (measured in parts-per-million or pounds/MMBtu) in the Clean Air Act creates a regulatory barrier to the installation and deployment of technologies that emit fewer criteria pollutants and use energy more efficiently. Changing emission management strategies to an output-based emissions standard (measured in tons of pollutant emitted) is a way to ameliorate some of these barriers. Combined heat and power (CHP) is one of the key technologies that would see increased industrial application if the emissions standards were modified. Many states have made this change since the EPA first approved it in 2000, although direction from the Federal government could speed implementation modifications. To analyze the national impact of accelerated state adoption of output-based standards on CHP technologies, this paper uses detailed National Energy Modeling System (NEMS) and spreadsheet analysis illustrating two phased-in adoption scenarios for output-based emissions standards in the industrial sector. Benefit/cost metrics are calculated from a private and public perspective, and also a social perspective that considers the criteria and carbon air pollution emissions. These scenarios are compared to the reference case of AEO 2010 and are quite favorable, with a social benefit-cost ratio of 16.0 for a five-year phase-in scenario. In addition, the appropriateness of the Federal role, applicability, technology readiness, and administrative feasibility are discussed.

  13. Magnetic and Fermi Surface Properties of Ferromagnets EuPd2 and EuPt2

    NASA Astrophysics Data System (ADS)

    Nakamura, Ai; Akamine, Hiromu; Ashitomi, Yousuke; Honda, Fuminori; Aoki, Dai; Takeuchi, Tetsuya; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Tatetsu, Yasutomi; Maehira, Takahiro; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-08-01

    We succeeded in growing single crystals of the ferromagnets EuPd2 and EuPt2 with the Laves-type cubic structure by the Bridgman method, namely, heating constituting materials in a Mo crucible up to a high temperature of about 1500 °C. The ferromagnetic properties of EuPd2 and EuPt2 with Curie temperatures of 74 and 100 K, respectively, were confirmed from the results of electrical resistivity, specific heat, and magnetization measurements. The ordered moment is 7 μB/Eu, revealing the Eu-divalent ferromagnetism. The present Eu-divalent electronic state is found to be robust against high pressures of up to 8 GPa and is not changed into the Eu-trivalent state. We also carried out de Haas-van Alphen (dHvA) experiments for EuPd2. The detected dHvA branches in EuPd2 are well explained by the relativistic linearized augmented plane wave (RLAPW) energy band calculations for SrPd2, revealing a closed hole Fermi surface and compensated four closed electron Fermi surfaces.

  14. Teaching Reform and Union Reform.

    ERIC Educational Resources Information Center

    Kerchner, Charles T.; Mitchell, Douglas E.

    1986-01-01

    Reviews present labor statutes and examines three alternatives to current practices; proposes that teaching, by its nature, is not well administered by industrial standards or well adjudicated through industrial unionism. Suggests "professional unionism" as a means of effecting educational reform. (DR)

  15. Energy-transfer efficiency in Eu-doped ZnO thin films: the effects of oxidative annealing on the dynamics and the intermediate defect states.

    PubMed

    Ahmed, Samah M; Szymanski, Paul; El-Nadi, Lotfia M; El-Sayed, Mostafa A

    2014-02-12

    We have studied ultrafast dynamics in thin films of Eu-doped zinc oxide (ZnO), prepared by radio-frequency sputtering onto sapphire substrates. Following UV excitation of ZnO, a red emission is observed. Postdeposition annealing in an oxygen atmosphere improves the crystallinity and emission intensity of the films, which are highly sensitive to the dopant concentration. Transient-absorption spectroscopy shows that the excited semiconductor host transfers energy to rare-earth ions on a time scale of only a few picoseconds. The dynamics as a function of the probe wavelength change dramatically after annealing, with annealed films showing the fastest dynamics at much lower wavelengths. Our results show that annealing greatly affects the defect energy levels of the films and the dynamics of the trapped carriers. Unannealed films show dynamics consistent with energy transfer from O vacancies to the dopant, while energy transfer in annealed samples involves acceptor-type defects such as Zn vacancies as intermediates. PMID:24397538

  16. Highly improved electroluminescence from a series of novel Eu(III) complexes with functional single-coordinate phosphine oxide ligands: tuning the intramolecular energy transfer, morphology, and carrier injection ability of the complexes.

    PubMed

    Xu, Hui; Yin, Kun; Huang, Wei

    2007-01-01

    The functional single-coordinate phosphine oxide ligands (4-diphenylaminophenyl)diphenylphosphine oxide (TAPO), (4-naphthalen-1-yl-phenylaminophenyl)diphenylphosphine oxide (NaDAPO), and 9-[4-(diphenylphosphinoyl)phenyl]-9H-carbazole (CPPO), as the direct combinations of hole-transporting moieties, and electron-transporting triphenylphosphine oxide (TPPO) were designed and synthesized (amines or carbazole), together with their Eu(III) complexes [Eu(tapo)(2)(tta)(3)] (1), [Eu(nadapo)(2)(tta)(3)] (2), and [Eu(cppo)(2)(tta)(3)] (3; TTA: 2-thenoyltrifluoroacetonate). The investigation indicated that by taking advantage of the modification inertia of the phosphine oxide ligands, the direct introduction of the hole-transport groups as chromophore made TAPO, NaDAPO, and CPPO obtain the most compact structure and mezzo S(1) and T(1) energy levels, which improved the intramolecular energy transfer in their Eu(III) complexes. The amorphous phase of 1-3 proved the weak intermolecular interaction, which resulted in extraordinarily low self-quenching of the complexes. The excellent double-carrier transport ability of the ligands was studied with Gaussian calculations, and the bipolar structure of TAPO and CPPO was proved. The great improvement of the double-carrier transport ability of 1-3 was shown by cyclic voltammetry. Their HOMO and LUMO energy levels of around 5.3 and 3.0 eV, respectively, are the best results for Eu(III) complexes reported so far. A single-layer organic light-emitting diode of 2 had the impressive brightness of 59 cd m(-2) which, to the best of our knowledge, is the highest reported so far. Both of the four-layer devices based on pure 1 and 2 had a maximum brightness of more than 1000 cd m(-2), turn-on voltages lower than 5 V, maximum external quantum yields of more than 3 % and excellent spectral stability. PMID:17918175

  17. A highly efficient white light (Sr3,Ca,Ba)(PO4)3Cl:Eu2+, Tb3+, Mn2+ phosphor via dual energy transfers for white light-emitting diodes.

    PubMed

    Chen, Xi; Dai, Pengpeng; Zhang, Xintong; Li, Cong; Lu, Shan; Wang, Xiuli; Jia, Yan; Liu, Yichun

    2014-04-01

    A series of single-phased (Sr3-x,Ca1-y-z,Ba)(PO4)3Cl (SCBPO_Cl):xEu(2+), yTb(3+), zMn(2+) phosphors were synthesized by high-temperature solid-state reaction, and luminescent properties of these phosphors were investigated by means of photoluminescence and microcathode luminescence (μ-CL). Under UV excitation, white-light emission was obtained from triactivated SCBPO_Cl phosphors via combining three emission bands centered at 450, 543, and 570 nm contributed by Eu(2+), Tb(3+), and Mn(2+), respectively. White-light emission with the three emission bands is further demonstrated in the fluorescence microscope images, CL spectrum, and μ-CL mappings, which strongly confirm that the luminescence distribution of as-prepared SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphors is very homogeneous. Both spectral overlapping and lifetime decay analyses suggest that dual energy transfers, that is, Eu(2+)→Tb(3+) and Eu(2+)→Mn(2+), play key roles in obtaining the white emission. The International Commission on Illumination value of white emission as well as luminescence quantum yield (51.2-81.4%) can be tuned by precisely controlling the content of Eu(2+), Tb(3+), and Mn(2+). These results suggest that this single-phased SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphor may have a potential application as a near-UV convertible white-light emission phosphor for phosphor-converted white light-emitting diode. PMID:24649898

  18. Wide-band excited Y6(WMo)(0.5)O12:Eu red phosphor for white light emitting diode: structure evolution, photoluminescence properties, and energy transfer mechanisms involved.

    PubMed

    Li, Huaiyong; Noh, Hyeon Mi; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Jang, Kiwan; Lee, Ho Sueb; Yi, Soung Soo

    2013-10-01

    Y6(WMo)(0.5)O12 activated with Eu(3+) ions was investigated as a red-emitting conversion phosphor for white light emitting diodes (WLEDs). The phosphors were synthesized by calcining a citrate-complexation precursor at different temperatures. The photoluminescence properties of the phosphors and the energy transfer mechanisms involved were studied as a function of structure evolution. It was found that the host lattices were crystallized in a cubic or a hexagonal phase depending on the synthesis conditions. Although all the phosphors showed intensive red emission under an excitation of near-UV or blue light due to energy transfer from the host lattices to Eu(3+) ions, the photoluminescence spectra and temporal decay features were found to vary significantly with the structure and crystallinity of the host lattice. The mechanisms of the energy transfer from the host lattices to Eu(3+) ions and energy quenching among Eu(3+) ions were discussed on the basis of structure evolution of the host lattice. Phosphors calcined at 800 and 1300 °C were suggested to be promising candidates for blue and near-UV light excited WLEDs, respectively. PMID:24041150

  19. Reforming Science Education.

    ERIC Educational Resources Information Center

    Donmoyer, Robert, Ed.; Merryfield, Merry M., Ed.

    1995-01-01

    This theme issue highlights the diversity of reform initiatives in order to provide a deep understanding of the complexities associated with educational reform in general and the reform of science education in particular. Systemic reform initiatives at the national and state levels along with locally-inspired efforts at reform are outlined.…

  20. Luminescence properties and energy transfer in the novel red emitting phosphors Ba2Ln(BO3)2Cl:Sm3+, Eu3+ (Ln=Y, Gd)

    NASA Astrophysics Data System (ADS)

    Fan, Yan; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Ju, Guifang

    2014-10-01

    A series of Sm3+/Eu3+ singly and co-doped Ba2Ln(BO3)2Cl (Ln=Y3+, Gd3+) phosphors were prepared via the solid-state method. The XRD results indicate that the as-prepared products keep the monoclinic structure with a P21/m space group of Ba2Ln(BO3)2Cl, which belongs to the isomorphic substitution for Ln3+ sites in the Ba2Yb(BO3)2Cl host. The photoluminescence (PL) spectra demonstrate that Ba2Ln(BO3)2Cl:Sm3+,Eu3+ emits red light centered at 593 nm under the 393 nm excitation which is in good agreement with the emission wavelength from near ultraviolet light-emitting diodes (LEDs). The luminescence decays suggest that the energy transfer from Sm3+ to Eu3+ ions in Ba2Ln(BO3)2Cl:Eu3+, Sm3+ occurs. All results mean that Ba2Ln(BO3)2Cl:Eu3+, Sm3+ phosphors exhibit potential to act as a kind of red phosphor for near ultraviolet white light-emitting diodes (w-LEDs).

  1. Selectivity of bis-triazinyl bipyridine ligands for americium(III) in Am/Eu separation by solvent extraction. Part 1. Quantum mechanical study on the structures of BTBP complexes and on the energy of the separation.

    PubMed

    Narbutt, Jerzy; Oziminski, Wojciech P

    2012-12-21

    Theoretical studies were carried out on two pairs of americium and europium complexes formed by tetra-N-dentate lipophilic BTBP ligands, neutral [ML(NO(3))(3)] and cationic [ML(2)](3+) where M = Am(III) or Eu(III), and L = 6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (C2-BTBP). Molecular structures of the complexes have been optimized at the B3LYP/6-31G(d) level and total energies of the complexes in various media were estimated using single point calculations performed at the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) levels of theory. In the calculations americium and europium ions were treated using pseudo-relativistic Stuttgart-Dresden effective core potentials and the accompanying basis sets. Selectivity in solvent extraction separation of two metal ions is a co-operative function of contributions from all extractable metal complexes, which depend on physico-chemical properties of each individual complex and on its relative amount in the system. Semi-quantitative analysis of BTBP selectivity in the Am/Eu separation process, based on the contributions from the two pairs of Am(III) and Eu(III) complexes, has been carried out. To calculate the energy of Am/Eu separation, a model of the extraction process was used, consisting of complex formation in water and transfer of the formed complex to the organic phase. Under the assumptions discussed in the paper, this simple two-step model results in reliable values of the calculated differences in the energy changes for each pair of the Am/Eu complexes in both steps of the process. The greater thermodynamic stability (in water) of the Am-BTBP complexes, as compared with the analogous Eu species, caused by greater covalency of the Am-N than Eu-N bonds, is most likely the main reason for BTBP selectivity in the separation of the two metal ions. The other potential reason, i.e. differences in lipophilic properties of the analogous complexes of Am and Eu, is less important with regard to this selectivity. PMID

  2. White long-lasting phosphorescence generation in a CaAl2Si2O8 : Eu2+, Mn2+, Dy3+ system through persistent energy transfer

    NASA Astrophysics Data System (ADS)

    Zhang, Jinsu; Chen, Baojiu; Sun, Jiashi; Li, Xiangping; Cheng, Lihong; Zhong, Haiyang

    2012-08-01

    Based on the persistent energy transfer principle, Mn2+ was introduced into a CaAl2Si2O8 : Eu2+/Dy3+ phosphor to achieve white long-lasting emissions. Eu2+, Mn2+ and Dy3+ tri-doped CaAl2Si2O8 phosphors with various Mn2+ concentrations were prepared via a solid-state reaction, and the crystal structure of the phosphors was identified by the x-ray diffraction technique. The luminescent properties of the Eu2+, Mn2+ and Dy3+ tri-doped CaAl2Si2O8 phosphors were studied. The energy transfer behaviour from Eu2+ to Mn2+ was analysed within the framework of Dexter theory. The physical mechanism of energy transfer was assigned to the electric dipole-quadrupole interaction. It was also demonstrated that the colour coordinates of the phosphors can be tuned from the blue region to the white region in the colour space. Furthermore, the afterglow decay and thermoluminescence curves were measured, indicating excellent phosphorescence properties of the current phosphors.

  3. A Strategy to enhance Eu3+ emission from LiYF4:Eu nanophosphors and green-to-orange multicolor tunable, transparent nanophosphor-polymer composites

    PubMed Central

    Kim, Su Yeon; Won, Yu-Ho; Jang, Ho Seong

    2015-01-01

    LiYF4:Eu nanophosphors with a single tetragonal phase are synthesized, and various strategies to enhance the Eu3+ emission from the nanophosphors are investigated. The optimized Eu3+ concentration is 35 mol%, and the red emission peaks due to the 5D0 →7FJ (J = 1 and 2) transitions of Eu3+ ions are further enhanced by energy transfer from a sensitizer pair of Ce3+ and Tb3+. The triple doping of Ce, Tb, and Eu into the LiYF4 host more effectively enhances the Eu3+ emission than the core/shell strategies of LiYF4:Eu(35%)/LiYF4:Ce(15%), Tb(15%) and LiYF4:Ce(15%), Tb(15%)/LiYF4:Eu(35%) architectures. Efficient energy transfer from Ce3+ to Eu3+ through Tb3+ results in three times higher Eu3+ emission intensity from LiYF4:Ce(15%), Tb(15%), Eu(1%) nanophosphors compared with LiYF4:Eu(35%), which contains the optimized Eu3+ concentration. Owing to the energy transfer of Ce3+ → Tb3+ and Ce3+ → Tb3+ → Eu3+, intense green and red emission peaks are observed from LiYF4:Ce(13%), Tb(14%), Eu(1-5%) (LiYF4:Ce, Tb, Eu) nanophosphors, and the intensity ratio of green to red emission is controlled by adjusting the Eu3+ concentration. With increasing Eu3+ concentration, the LiYF4:Ce, Tb, Eu nanophosphors exhibit multicolor emission from green to orange. In addition, the successful incorporation of LiYF4:Ce, Tb, Eu nanophosphors into polydimethylsiloxane (PDMS) facilitates the preparation of highly transparent nanophosphor-PDMS composites that present excellent multicolor tunability. PMID:25597900

  4. Applications of solar reforming technology

    SciTech Connect

    Spiewak, I.; Tyner, C.E.; Langnickel, U.

    1993-11-01

    Research in recent years has demonstrated the efficient use of solar thermal energy for driving endothermic chemical reforming reactions in which hydrocarbons are reacted to form synthesis gas (syngas). Closed-loop reforming/methanation systems can be used for storage and transport of process heat and for short-term storage for peaking power generation. Open-loop systems can be used for direct fuel production; for production of syngas feedstock for further processing to specialty chemicals and plastics and bulk ammonia, hydrogen, and liquid fuels; and directly for industrial processes such as iron ore reduction. In addition, reforming of organic chemical wastes and hazardous materials can be accomplished using the high-efficiency destruction capabilities of steam reforming. To help identify the most promising areas for future development of this technology, we discuss in this paper the economics and market potential of these applications.

  5. [Curricular reform].

    PubMed

    Fraga Filho, C; Rosa, A R

    1980-01-01

    Advocating the thesis that the planning of medical education must be oriented toward the articulastion of instruction with care, the authors note that the curricular reforms of the last 25 years, though reflected in the teaching-learning process, have led to no improvement in medical practice or in the health of the population. This failing, they assert, stems from the fact that these reforms begin and end within the educational institution itself, and ignore the interrelations between the education system and the user of the professional, and results in the production of physicians who are individualistic and of narrow vision. The article refers to the slight importance attached to the complementarity and interdependence of teaching and care work, and to the restriction of teaching to episodic contacts between specialized professors and groups of anonymous students, each in the limited confines of his own discipline, and the relegation of the student to the status of spectator and possible assistant in care work entrusted to him without any responsibility. PMID:7398573

  6. Tunable-color luminescence via energy transfer in NaCa13/18Mg5/18PO4:A (A = Eu2+/Tb3+/Mn2+, Dy3+) phosphors for solid state lighting.

    PubMed

    Li, Kai; Fan, Jian; Mi, Xiaoyun; Zhang, Yang; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

    2014-11-17

    A series of NaCa13/18Mg5/18PO4(NCMPO):A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) phosphors have been prepared by the high-temperature solid-state reaction method. The X-ray diffraction (XRD) and Rietveld refinement, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cathodoluminescence (CL), decay lifetimes, and PL quantum yields (QYs) were utilized to characterize the phosphors. The pure crystalline phase of as-prepared samples has been demonstrated via XRD measurement and Rietveld refinements. XPS reveals that the Eu(2+)/Tb(3+)/Mn(2+) can be efficiently doped into the crystal lattice. NCMPO:Eu(2+)/Tb(3+)/Mn(2+) phosphors can be effectively excited under UV radiation, which show tunable color from purple-blue to red including white emission based on energy transfer from Eu(2+) to Tb(3+)/Mn(2+) ions. Under low-voltage electron beam bombardment, the NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) display their, respectively, characteristic emissions with different colors, and the CL spectrum of NCMPO:0.04Tb(3+) has the comparable intensity to the ZnO:Zn commercial product. In addition, the calculated CIE coordinate of NCMPO:0.04Tb(3+) (0.252, 0.432) is more saturated than it (0.195, 0.417). These results reveal that NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) may be potential candidate phosphors for WLEDs and FEDs. PMID:25375961

  7. Gas-to-liquids synthetic fuels for use in fuel cells : reformability, energy density, and infrastructure compatibility.

    SciTech Connect

    Ahmed, S.; Kopasz, J. P.; Russell, B. J.; Tomlinson, H. L.

    1999-09-08

    The fuel cell has many potential applications, from power sources for electric hybrid vehicles to small power plants for commercial buildings. The choice of fuel will be critical to the pace of its commercialization. This paper reviews the various liquid fuels being considered as an alternative to direct hydrogen gas for the fuel cell application, presents calculations of the hydrogen and carbon dioxide yields from autothermal reforming of candidate liquid fuels, and reports the product gas composition measured from the autothermal reforming of a synthetic fuel in a micro-reactor. The hydrogen yield for a synthetic paraffin fuel produced by a cobalt-based Fischer-Tropsch process was found to be similar to that of retail gasoline. The advantages of the synthetic fuel are that it contains no contaminants that would poison the fuel cell catalyst, is relatively benign to the environment, and could be transported in the existing fuel distribution system.

  8. On the Luminescence Enhancement of Mn2+ By Co-doping of Eu2+ in ZnS:Mn,Eu

    SciTech Connect

    Hossu, Marius; Schaeffer, Roger O.; Ma, Lun; Chen, Wei; Zhu, Yongbin; Sammynaiken, Ramaswami; Joly, Alan G.

    2013-06-01

    The photoluminescence and X-ray luminescence of ZnS:Mn, ZnS:Mn,Eu and ZnS:Eu were investigated and it was found that the luminescence intensity of Mn2+ in ZnS:Mn,Eu co-doped phosphors is highly dependent on the doping concentration of Eu2+. At the optimized Eu2+concentration (0.2%), the photoluminescence of Mn2+ shows about a 5.5 times enhancement and its X-ray luminescence is enhanced by a factor of 2.5. Both wurtzite and zinc blend phases are present in the samples with wurtzite phase dominant. Co-doping of Eu2+ into ZnS:Mn does not change appreciably the ratio of the two phases or the Mn2+ emission luminescence lifetime; however, the doping of Eu2+ into ZnS:Mn does change the phonon activity. Furthermore, it was found that the defect-related blue emission of ZnS:Eu overlaps with the excitation bands of Mn2+ in ZnS:Mn and there is likely energy transfer from these defect states to Mn2+ in ZnS:Mn,Eu. This energy transfer and the phonon modification are considered to be the two main reasons for the luminescence enhancement and the intensity dependence of Mn2+ emission on Eu2+ doping concentration in ZnS:Mn,Eu.

  9. Reforming Again: Now Teachers

    ERIC Educational Resources Information Center

    Marx, Ronald W.

    2014-01-01

    Background: Educational reform responds to local and national pressures to improve educational outcomes, and reform efforts cycle as similar pressures recur. Currently, reform efforts focus on teachers, even though confidence in a host of American social institutions is dropping. One of the most widespread reforms regarding teachers is the…

  10. Fuel cell integrated with steam reformer

    DOEpatents

    Beshty, Bahjat S.; Whelan, James A.

    1987-01-01

    A H.sub.2 -air fuel cell integrated with a steam reformer is disclosed wherein a superheated water/methanol mixture is fed to a catalytic reformer to provide a continuous supply of hydrogen to the fuel cell, the gases exhausted from the anode of the fuel cell providing the thermal energy, via combustion, for superheating the water/methanol mixture.

  11. Controlling the energy transfer via multi luminescent centers to achieve white light/tunable emissions in a single-phased X2-type Y2SiO5:Eu(3+),Bi(3+) phosphor for ultraviolet converted LEDs.

    PubMed

    Kang, Fengwen; Zhang, Yi; Peng, Mingying

    2015-02-16

    So far, more than 1000 UV converted phosphors have been reported for potential application in white light-emitting diodes (WLEDs), but most of them (e.g., Y2O2S:Eu, YAG:Ce or CaAlSiN3:Eu) suffer from intrinsic problems such as thermal instability, color aging or re-absorption by commixed phosphors in the coating of the devices. In this case, it becomes significant to search a single-phased phosphor, which can efficiently convert UV light to white lights. Herein, we report a promising candidate of a white light emitting X2-type Y2SiO5:Eu(3+),Bi(3+) phosphor, which can be excitable by UV light and address the problems mentioned above. Single Bi(3+)-doped X2-type Y2SiO5 exhibits three discernible emission peaks at ∼355, ∼408, and ∼504 nm, respectively, upon UV excitation due to three types of bismuth emission centers, and their relative intensity depends tightly on the incident excitation wavelength. In this regard, proper selection of excitation wavelength can lead to tunable emissions of Y2SiO5:Bi(3+) between blue and green, which is partially due to the energy transfer among the Bi centers. As a red emission center Eu(3+) is codoped into Y2SiO5:Bi(3+), energy transfer has been confirmed happening from Bi(3+) to Eu(3+) via an electric dipole-dipole (d-d) interaction. Our experiments reveal that it is easily realizable to create the white or tunable emissions by adjusting the Eu(3+) content and the excitation schemes. Moreover, a single-phased white light emission phosphor, X2-type Y1.998SiO5:0.01Eu(3+),0.01 Bi(3+), has been achieved with excellent resistance against thermal quenching and a QE of 78%. At 200 °C, it preserves >90% emission intensity of that at 25 °C. Consequent three time yoyo experiments of heating-cooling prove no occurrence of thermal degradation. A WLED lamp has been successfully fabricated with a CIE chromaticity coordinate (0.3702, 0.2933), color temperature 4756 K, and color rendering index of 65 by applying the phosphor onto a UV LED

  12. Sexism in School Textbooks Prepared under Education Reform in Turkey

    ERIC Educational Resources Information Center

    Esen, Yasemin

    2007-01-01

    The objective of this study is to analyze the new textbooks prepared under the framework of the "curriculum reform" realized in Turkey , as part of the EU harmonization process, in terms of gender representation. For this purpose, illustrations in the new ABC, Life Studies and Social Studies textbooks prepared under the new program were analyzed…

  13. Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

    SciTech Connect

    Jiao, Qing; Qiu, Jianbei; Zhou, Dacheng; Xu, Xuhui

    2014-03-01

    Graphical abstract: - Highlights: • Silver nanoparticles are precipitated from the borate glasses during the melting process without any further heat treatment. • The reduction of Eu{sup 3+} ions to Eu{sup 2+} ions is presented in this material. • The intensity of Ag{sup +} luminescence. • The introduction of Eu ions accelerated the reaction between Eu{sup 2+} ions and silver ions inducing the silver clusters formation. - Abstract: Ag{sup +} doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410 nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag{sup +} decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu{sup 3+} to Eu{sup 2+} in our glass system, it revealed that Ag{sup +} has been reduced by the neighboring Eu{sup 2+} which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag{sup +}/Ag aggregates to the Eu{sup 3+} was investigated for the enhancement of Eu{sup 3+} luminescence.

  14. Ab initio approaches for the determination of heavy element energetics: Ionization energies of trivalent lanthanides (Ln = La-Eu)

    SciTech Connect

    Peterson, Charles; Penchoff, Deborah A.; Wilson, Angela K.

    2015-11-21

    An effective approach for the determination of lanthanide energetics, as demonstrated by application to the third ionization energy (in the gas phase) for the first half of the lanthanide series, has been developed. This approach uses a combination of highly correlated and fully relativistic ab initio methods to accurately describe the electronic structure of heavy elements. Both scalar and fully relativistic methods are used to achieve an approach that is both computationally feasible and accurate. The impact of basis set choice and the number of electrons included in the correlation space has also been examined.

  15. Photoluminescence and Energy Transfer Properties with Y+SiO4 Substituting Ba+PO4 in Ba3Y(PO4)3:Ce(3+)/Tb(3+), Tb(3+)/Eu(3+) Phosphors for w-LEDs.

    PubMed

    Li, Kai; Liang, Sisi; Shang, Mengmeng; Lian, Hongzhou; Lin, Jun

    2016-08-01

    A series of Ce(3+), Tb(3+), Eu(3+) doped Ba2Y2(PO4)2(SiO4) (BYSPO) phosphors were synthesized via the high-temperature solid-state reaction route. X-ray diffraction, high-resolution transmission electron microscopy, Fourier transform infrared, solid-state NMR, photoluminescence (PL) including temperature-dependent PL, and fluorescent decay measurements were conducted to characterize and analyze as-prepared samples. BYSPO was obtained by the substitution of Y+SiO4 for Ba+PO4 in Ba3Y(PO4)3 (BYPO). The red shift of PL emission from 375 to 401 nm occurs by comparing BYSPO:0.14Ce(3+) with BYPO:0.14Ce(3+) under 323 nm UV excitation. More importantly, the excitation edge can be extended from 350 to 400 nm, which makes it be excited by UV/n-UV chips (330-410 nm). Tunable emission color from blue to green can be observed under 365 nm UV excitation based on the energy transfer from Ce(3+) to Tb(3+) ions after codoping Tb(3+) into BYSPO:0.14Ce(3+). Moreover, energy transfer from Tb(3+) to Eu(3+) ions also can be found in BYSPO:Tb(3+),Eu(3+) phosphors, resulting in the tunable color from green to orange red upon 377 nm UV excitation. Energy transfer properties were demonstrated by overlap of excitation spectra, variations of emission spectra, and decay times. In addition, energy transfer mechanisms from Ce(3+) to Tb(3+) and Tb(3+) to Eu(3+) in BYSPO were also discussed in detail. Quantum yields and CIE chromatic coordinates were also presented. Generally, the results suggest their potential applications in UV/n-UV pumped LEDs. PMID:27415966

  16. Phase controlled colour tuning of samarium and europium complexes and excellent photostability of their PVA encapsulated materials. Structural elucidation, photophysical parameters and the energy transfer mechanism in the Eu(3+) complex by Sparkle/PM3 calculations.

    PubMed

    Dar, Wakeel Ahmed; Iftikhar, K

    2016-06-01

    Luminescent [Sm(acac)3(pyz)2] (1) and [Eu(acac)3(pyz)2] (2) complexes (acac is the anion of acetylacetone and pyz is pyrazine) have been synthesized and thoroughly characterized by microanalyses, TGA, DTA, IR, ESI-MS(+) and NMR spectroscopy. The photophysical properties of these complexes have been investigated. The Sparkle/PM3 model was utilized for predicting the ground-state geometry of (2). The Judd-Ofelt intensity parameters, radiative parameters, intramolecular energy transfer rates and quantum efficiency are calculated and discussed. The intramolecular energy transfer rates predict that the major energy transfer (96%) is from the ligand triplet state to the levels (5)D1 (74.53%) and (5)D0 (21.87%) of the Eu(3+) ion, in the complex. Complexes (1) and (2) were analysed for colour tuning properties and these show varying colours upon changing phases. This property would possibly allow the use of these complexes as 'colour indicators'. The photoluminescence and photostability of the thin hybrid films of both complexes (1) and (2) in polyvinyl alcohol (PVA) are investigated and discussed. The hybrid films of (1) and (2) are quite robust due to their higher photostability. An important feature of complex (2) is that the excitation window extends close to the visible range (393 nm). The lasing property of the Eu(3+) complex in various phases is also presented. PMID:27157414

  17. Evidence of Eu{sup 2+} 4f electrons in the valence band spectra of EuTiO{sub 3} and EuZrO{sub 3}

    SciTech Connect

    Kolodiazhnyi, T.; Valant, M.; Williams, J. R.; Bugnet, M.; Botton, G. A.; Ohashi, N.; Sakka, Y.

    2012-10-15

    We report on optical band gap and valence electronic structure of two Eu{sup 2+}-based perovskites, EuTiO{sub 3} and EuZrO{sub 3} as revealed by diffuse optical scattering, electron energy loss spectroscopy, and valence-band x-ray photoelectron spectroscopy. The data show good agreement with the first-principles studies in which the top of the valence band structure is formed by the narrow Eu 4f{sup 7} electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO{sub 3} perovskites except that it is shifted to higher binding energies. Appearance of the Eu{sup 2+} 4f{sup 7} band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  18. [Influence of Eu2+ content on the spectral characteristics of BaMgAl10O17 : Eu2+ phosphors].

    PubMed

    Chen, Zhe; Xie, Hong; Yan, You-Wei

    2007-04-01

    Nanocrsytalline Ba(1-x)MgAl10O17 : xEu2+ (0.05 < or = x < or = 0.4) blue-emitting phosphor was successfully prepared by low-temperature combustion synthesis. The influence of different Eu content on the spectral characteristics of Ba(1-x) MgAl10O17 : xEu2+ was mainly investigated. The results of XRD and SEM analysis show that the sample is single phase and its average grain size is about 30 nm. The luminescence property of Ba(1-x)MgAl10O17 : xEu2+ phosphor is considerably influenced by Eu2+ concentration. In an appropriate Eu2+ doping concentration range, the intensity of the fluorescence of Ba(1-x)MgAl10O17 : xEu2+ was increased obviously with increasing the Eu2+ doping concentration, owing to adding the number of luminescent centers and enhancing the energy transfer between Eu2+ ions. The optimum emission intensity was reached at x = 0.2. However, as the Eu2+ doping concentration was higher than 0.2, the intensity of the fluorescence was reduced, due to the concentration quenching occurrence. PMID:17608168

  19. European Education Reform and Its Impact on Curriculum and Admissions: Implications of the Bologna Process on United States Education

    ERIC Educational Resources Information Center

    Roper, Steven D.

    2007-01-01

    This article explores the European-wide educational reform known as the Bologna Process in order to provide an understanding of the methodology that will be used by European countries to assess course credit hours as well as degree programs. The Bologna Process is culmination of years of educational reform within the European Union (EU) and more…

  20. Less Developed Countries (LDCs) Facing Higher Education Curricula Reform Challenges in a "New World (Dis)Order"

    ERIC Educational Resources Information Center

    Gilder, Eric

    2011-01-01

    In a previous article for "EJHE," I detailed Curricula Reform (CR) efforts in Higher Education (HE) in four (relatively) well developed regional and national settings (The EU, the USA, Hong Kong SAR China, and Singapore). I detailed the backdrop motivating the moves by policymakers to reform the curricula in such "world class"…

  1. Reform before NCLB

    ERIC Educational Resources Information Center

    Desimone, Laura M.

    2013-01-01

    The author compared NCLB-prompted standards-based reforms with earlier reforms and found that earlier manifestations of standards-based reforms may have been more productive and constructive. NCLB, with its emphasis on accountability through high-stakes testing, has produced many perverse results alongside documented achievement gains, the author…

  2. Sputnik Reform Revisited.

    ERIC Educational Resources Information Center

    Strickland, Charles E.

    1985-01-01

    Educational reforms being called for in the 1980's are compared to reforms of the 1950's. The Sputnik-inspired quest for quality called for reform in the content and structure of basic subjects. Current reports say that what educators are doing in the basic subjects is ok, but they need to do more. (RM)

  3. Reforming Special Education.

    ERIC Educational Resources Information Center

    Fishkin, Anne S.; Sullivan, Michael

    This paper describes education reform as an integrated effort to modify not only the structure and elements of the education system but also the culture or belief structure of that system. Central to any discussion of school reform are the elements of restructuring, empowerment, and change. Current reform efforts in restructuring revolve around a…

  4. Anchors for Education Reforms

    ERIC Educational Resources Information Center

    Alok, Kumar

    2012-01-01

    Education reforms, considering their significance, deserve better methods than mere "trial and error." This article conceptualizes a network of six anchors for education reforms: education policy, education system, curriculum, pedagogy, assessment, and teacher education. It establishes the futility to reform anchors in isolation and anticipates…

  5. Beyond Reform: Transformation

    ERIC Educational Resources Information Center

    Davidson, Jill

    2007-01-01

    The Coalition of Essential Schools (CES) is not a reform movement. To reform is to make a thing again; reformation implies a stasis that doesn't deliver enough for the educational future. This issue of Horace demonstrates that Essential schools and the districts and networks that support them are at various points in the journey of transformation,…

  6. On the energy scale involved in the metal to insulator transition of quadruple perovskite EuCu3Fe4O12: infrared spectroscopy and ab-initio calculations

    PubMed Central

    Brière, B.; Kalinko, A.; Yamada, I.; Roy, P.; Brubach, J. B.; Sopracase, R.; Zaghrioui, M.; Phuoc, V. Ta

    2016-01-01

    Optical measurements were carried out by infrared spectroscopy on AA′3B4O12 A-site ordered quadruple perovskite EuCu3Fe4O12 (microscopic sample) as function of temperature. At 240 K (=TMI), EuCu3Fe4O12 undergoes a very abrupt metal to insulator transition, a paramagnetic to antiferromagnetic transition and an isostructural transformation with an abrupt large volume expansion. Above TMI, optical conductivity reveals a bad metal behavior and below TMI, an insulating phase with an optical gap of 125 meV is observed. As temperature is decreased, a large and abrupt spectral weight transfer toward an energy scale larger than 1 eV is detected. Concurrently, electronic structure calculations for both high and low temperature phases were compared to the optical conductivity results giving a precise pattern of the transition. Density of states and computed optical conductivity analysis identified Cu3dxy, Fe3d and O2p orbitals as principal actors of the spectral weight transfer. The present work constitutes a first step to shed light on EuCu3Fe4O12 electronic properties with optical measurements and ab-initio calculations. PMID:27346212

  7. Optical properties of Eu{sup 2+}/Eu{sup 3+} mixed valence, silicon nitride based materials

    SciTech Connect

    Kate, Otmar M. ten; Vranken, Thomas; Kolk, Erik van der; Jansen, Antonius P.J.; Hintzen, Hubertus T.

    2014-05-01

    Eu{sub 2}SiN{sub 3}, a mixed valence europium nitridosilicate, has been prepared via solid-state reaction synthesis and its oxidation behavior and optical properties have been determined. Furthermore, the stability of several isostructural compounds of the type M{sup 2+}L{sup 3+}SiN{sub 3} has been predicted by using the density functional theory calculations, and verified by the actual synthesis of CaLaSiN{sub 3}, CaEuSiN{sub 3} and EuLaSiN{sub 3}. The band gap of CaLaSiN{sub 3} was found around 3.2 eV giving the material its yellow color. Eu{sub 2}SiN{sub 3} on the other hand is black due to a combination of the 4f–5d absorption band of Eu{sup 2+} and the charge transfer band of Eu{sup 3+}. Thermogravimetric analysis and Raman spectroscopic study of Eu{sub 2}SiN{sub 3} revealed that oxidation of this compound in dry air takes place via a nitrogen retention complex. - Graphical abstract: Energy level scheme of Eu{sub 2}SiN{sub 3} showing the occupied N{sup 3−} 2p band (blue rectangle), unoccupied Eu{sup 2+} 5d band (white rectangle), occupied Eu{sup 2+} 4f ground states (filled red circles) and unoccupied Eu{sup 2+} ground states (open red circles). - Highlights: • Density functional theory calculations on the stability of M{sup 2+}L{sup 3+}SiN{sub 3} compounds. • Solid-state reaction synthesis of Eu{sub 2}SiN{sub 3}, CaLaSiN{sub 3}, EuLaSiN{sub 3} and CaEuSiN{sub 3}. • Determination of the Eu{sup 2+} 4f–5d and Eu{sup 3+} CT transitions in M{sup 2+}L{sup 3+}SiN{sub 3} compounds. • Oxidation of Eu{sub 2}SiN{sub 3} in dry air takes place via a nitrogen retention complex.

  8. Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe

    SciTech Connect

    Rocquefelte, Xavier; Gautier, Regis; Halet, Jean-Francois Muellmann, Ralf; Rosenhahn, Carsten; Mosel, Bernd D.; Kotzyba, Gunter; Poettgen, Rainer

    2007-02-15

    EuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1){mu} {sub B}/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at T {sub N}=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1){mu} {sub B}/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000{+-}500 {mu}{omega} cm for the specific resistivity. {sup 151}Eu Moessbauer spectroscopic experiments show a single europium site with an isomer shift of {delta}=-9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu{sup 2+} T {sup 0}Ge{sup 2-} seems more appropriate than Eu{sup 2+} T {sup 2+}Ge{sup 4-} accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types. - Graphical abstract: Cutouts of the [PdGe] and [PtGe] polyanions in the structures of EuPdGe and EuPtGe. Atom designations and some relevant interatomic distances are given.

  9. Thermoluminescence response of K{sub 2}Ca{sub 2}(SO{sub 4}){sub 3} nanophosphor Co-doped with Eu and Ce for gamma ray dosimetry

    SciTech Connect

    Patil, B. J.; Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.; Mandlik, N. T.; Kulkarni, M. S.; Bhatt, B. C.

    2015-06-24

    K{sub 2}Ca{sub 2}(SO{sub 4}){sub 3} nanophosphors co-doped with Eu and Ce were synthesized by the chemical co-precipitation method. These samples were further annealed at 700 °C structural reformation. The structural and morphological characteristics were studied using XRD and TEM techniques. The particle size calculated from XRD spectra was around 35 nm. The as synthesized sample shows cubic structure annealed at 700 °C. The as synthesized and annealed sample of K{sub 2}Ca{sub 2}(SO{sub 4}){sub 3}: EuCe were irradiated with Co{sup 60} gamma rays for the doses from 2Gy to 1kGy. The TL characteristic sample of co-doped were studied for the dosimetric application by gamma radiation. The TL spectrum of annealed sample has single peaked at 160 °C. The Eu doped sample has a high TL sensitivity than Ce doped sample. But after co-doping with Eu and Ce, TL intensity observed to be decreased. The decrees in TL peak intensity of the phosphor on co-doping of Eu and Ce gives an insight into the emission mechanism of the phosphor which involves energy transfer from Eu to Ce. The TL response of all the samples were found to be linear for the dose from 2 Gy to 1 KGy. Therefore, K{sub 2}Ca{sub 2}(SO{sub 4}){sub 3}: EuCe nanophosphor can be used for the measurement of high dose of gamma radiation.

  10. Search for linking transitions in {sup 143}Eu

    SciTech Connect

    Lerma, F.; LaFosse, D.R.; Devlin, M.

    1996-12-31

    Six SD bands were populated in {sup 143}Eu and {sup 144}Eu, two of which had not been previously observed. Sum spectra were generated to search for two step links from the yrast SD band in {sup 143}Eu. However, no two step links were found. A single link from the SD band in {sup 143}Eu was found at 3364 keV. The level where it feeds into has not been identified. Alpha-particle energy (E{sub {alpha}}) spectra leading to the SD band and to normal states in {sup 143}Eu were measured and a correlation was found between E{sub {alpha}} and the level spin of the residual nucleus.

  11. [Gd-doped natural thenardite: Eu photoluminescence properties of europium].

    PubMed

    Guzaliayi, Juman; Tuerxun, Aidilibike; Aizitiaili, Abulizi; Aierken, Sidike

    2012-06-01

    The authors prepared Na2SO4: Eu, Gd, and Na2Gd2 (SO4)4: Eu phosphors by heating, the mixed powder of GdF3, EuF3 and natural mirabilite with muffle furnace at 1 000 degrees C for 30 min and continually heating it with microwave at 750 degrees C for 10 min. With increasing the concentrations of Gd ion, the 610 nm emission intensity due to Eu3+ was strengthened. Gd3+ probably formed a bridge between substrate and the activator so that the energy is able to be transferred efficiently. The luminescence intensity, along with colorimetric purity, reaches the top with 21 mol% Gd3+ doping in the thenardite (Na2SO4: Eu) lattices, eventually coming up the quenching effects of concentration. PMID:22870627

  12. European hospital reforms in times of crisis: aligning cost containment needs with plans for structural redesign?

    PubMed

    Clemens, Timo; Michelsen, Kai; Commers, Matt; Garel, Pascal; Dowdeswell, Barrie; Brand, Helmut

    2014-07-01

    Hospitals have become a focal point for health care reform strategies in many European countries during the current financial crisis. It has been called for both, short-term reforms to reduce costs and long-term changes to improve the performance in the long run. On the basis of a literature and document analysis this study analyses how EU member states align short-term and long-term pressures for hospital reforms in times of the financial crisis and assesses the EU's influence on the national reform agenda. The results reveal that there has been an emphasis on cost containment measures rather than embarking on structural redesign of the hospital sector and its position within the broader health care system. The EU influences hospital reform efforts through its enhanced economic framework governance which determines key aspects of the financial context for hospitals in some countries. In addition, the EU health policy agenda which increasingly addresses health system questions stimulates the process of structural hospital reforms by knowledge generation, policy advice and financial incentives. We conclude that successful reforms in such a period would arguably need to address both the organisational and financing sides to hospital care. Moreover, critical to structural reform is a widely held acknowledgement of shortfalls in the current system and belief that new models of hospital care can deliver solutions to overcome these deficits. Advancing the structural redesign of the hospital sector while pressured to contain cost in the short-term is not an easy task and only slowly emerging in Europe. PMID:24703855

  13. Low-lying electronic structure of EuH, EuOH, and EuO neutrals and anions determined by anion photoelectron spectroscopy and DFT calculations

    SciTech Connect

    Kafader, Jared O.; Ray, Manisha; Jarrold, Caroline Chick

    2015-07-21

    The anion photoelectron (PE) spectra of EuH{sup −} and the PE spectrum of overlapping EuOH{sup −} and EuO{sup −} anions are presented and analyzed with supporting results from density functional theory calculations on the various anions and neutrals. Results point to ionically bound, high-spin species. EuH and EuOH anions and neutrals exhibit analogous electronic structures: Transitions from {sup 8}Σ{sup −} anion ground states arising from the 4f{sup 7}σ{sub 6s}{sup 2} superconfiguration to the close-lying neutral {sup 9}Σ{sup −} and {sup 7}Σ{sup −} states arising from the 4f{sup 7}σ{sub 6s} superconfiguration are observed spaced by an energy interval similar to the free Eu{sup +} [4f{sup 7}6s] {sup 9}S - {sup 7}S splitting. The electron affinities (EAs) of EuH and EuOH are determined to be 0.771 ± 0.009 eV and 0.700 ± 0.011 eV, respectively. Analysis of spectroscopic features attributed to EuO{sup −} photodetachment is complicated by the likely presence of two energetically competitive electronic states of EuO{sup −} populating the ion beam. However, based on the calculated relative energies of the close-lying anion states arising from the 4f{sup 7}σ{sub 6s} and 4f{sup 6}σ{sub 6s}{sup 2} configurations and the relative energies of the one-electron accessible 4f{sup 7} and 4f{sup 6}σ{sub 6s} neutral states based on ligand-field theory [M. Dulick, E. Murad, and R. F. Barrow, J. Chem. Phys. 85, 385 (1986)], the remaining features are consistent with the 4f{sup 6}σ{sub 6s}{sup 2}  {sup 7}Σ{sup −} and 4f{sup 7}σ{sub 6s}{sup 7}Σ{sup −} anion states lying very close in energy (the former was calculated to be 0.15 eV lower in energy than the latter), though the true anion ground state and neutral EA could not be established unambiguously. Calculations on the various EuO anion and neutral states suggest 4f-orbital overlap with 2p orbitals in species with 4f{sup 6} occupancy.

  14. Eu2+ and Eu3+ based "concentrated phosphors" as converters for UV LED light: two approaches and two new examples

    NASA Astrophysics Data System (ADS)

    Batentschuk, M.; Geisler, R.; Hum, J.; Iqbal, F.; Meister, F.; Osvet, A.; Stiegelschmitt, A.; Winnacker, A.

    2012-01-01

    The absolute majority of phosphors are composed of a host lattice and some percentage of an activator. At higher activator concentrations the concentration quenching occurs. However, there are phosphors in which only minor quenching of the emission occurs with increasing of the activator content. Based on the existence of two different valence states of the Eu ion (2+ and 3+), two approaches for the development of "concentrated phosphors", i.e. light emitting materials in which the activator ion is a main part of the crystal lattice, are discussed. In both approaches, reduced energy migration leading to the luminescence quenching is considered as a main condition to reach a high quantum efficiency of a concentrated phosphor. Two kinds of phosphors—Eu2+-doped alumosilicate and Eu3+-doped oxyfluoride—are used as an experimental basis for this discussion. Starting from the stoichiometric Ca_{1-x}Eux^{2+}Al2Si2O8 anorthite and Eu3+OF oxyfluorides, the non-stoichiometric powders with Eu^{2+}_{0.92}Al_{1.76}Si_{2.24}O8, Eu3+(O, F)2,35 and Eu3+(O, F)2,16 compositions were synthesized by a solid state reaction and investigated. It was shown that—in spite of the almost 100% Eu concentration—light converters with high quantum efficiency of more than 45% can be realized. A possible application of these materials as UV LED light converters for white light emitting diodes are discussed as well.

  15. Educational Reform in Mexico.

    ERIC Educational Resources Information Center

    Fuentes, Bertha Orozco; Elizando Y Carr, Sandra

    1993-01-01

    Since the 1970s, each presidential regime has presented an educational modernization reform program for Mexico. Although the various reforms have widened educational opportunities, the quality of education has continued to deteriorate because of student and teacher desertion, a low scholastic progress index, accessibility problems, lack of an…

  16. Small Schools Reform Narratives

    ERIC Educational Resources Information Center

    Lehman, Beth M.; Berghoff, Beth

    2013-01-01

    This study explored complicated personal narratives of school reform generated by participants in response to a particular small schools reform initiative. Narrative data was dialogically generated in interviews with nine past participants of an urban high school conversion project planned and implemented over a span of five years toward the goal…

  17. Orthographic Reform in Kope.

    ERIC Educational Resources Information Center

    Clifton, John M.

    The role of local attitudes in recent orthographic reform in Kope is examined. The previous Kope orthographic tradition is outlined, and two areas apparently requiring reform (nasal/fricative variation and vowel clusters versus semivowels). The concerns and the greater awareness among the locals regarding these orthographic changes are explored.…

  18. Educational Reform in Oklahoma.

    ERIC Educational Resources Information Center

    Butorac, Marylin M.; First, Patricia F.

    1994-01-01

    Oklahoma's answer to the cry for reform and involvement in education emerged as House Bill 1017, a comprehensive $223 million school reform and tax act. This article reviews the HR 1017 story, focusing on its legislative enactment history and offering a content analysis of mandated changes in finance, personnel, governance, student assessment,…

  19. Reform: To What End?

    ERIC Educational Resources Information Center

    Rose, Mike

    2010-01-01

    The author looks at school reform in light of his experiences documenting effective public education in classrooms across the United States. Observing in an inner-city 1st grade classroom, he sees a teacher who is knowledgeable, resourceful, and particularly effective with her students. He notes that none of the current high-profile reform ideas…

  20. Two measured completely different electron affinities for atomic Eu?

    NASA Astrophysics Data System (ADS)

    Msezane, A. Z.; Felfli, Z.

    2016-05-01

    Recently, the electron affinity (EA) of atomic Eu was measured to be 0.116?eV. This value is in outstanding agreement with the theoretically calculated values using the Regge pole and MCDF-RCI methods. Previously, the EA of Eu was measured to be 1.053 eV. In an attempt to resolve the discrepancy between the two measured values, we have adopted the complex angular momentum (CAM) method and investigated in the electron energy range 0.11 eV energies (BEs) of negative ions formed during the collision of an electron with atomic Eu as Regge resonances following Ref.. We find the value of 2.63 eV as the EA of Eu. This leads us to conclude that neither the claimed measured EA of Eu correspond to the actual EA of Eu. We conclude that the EA in corresponds to the BE of an excited (metastable) state of the Euanion and that in to a shape resonance. We have also investigated the EA of atomic Nd and found the value of 1.88 eV, consistent with the measurement. These significant EA values of Eu and Nd could be important in the use of their negative ions in catalyzing the oxidation of water to peroxide and of methane to methanol without CO2 emission. These new results call for immediate experimental and theoretical verification.

  1. Plasma catalytic reforming of methane

    SciTech Connect

    Bromberg, L.; Cohn, D.R.; Rabinovich, A.; Alexeev, N.

    1998-08-01

    Thermal plasma technology can be efficiently used in the production of hydrogen and hydrogen-rich gases from methane and a variety of fuels. This paper describes progress in plasma reforming experiments and calculations of high temperature conversion of methane using heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely high temperatures (several thousand degrees Celsius) and high degree of dissociation and substantial degree of ionization. The high temperatures accelerate the reactions involved in the reforming process. Hydrogen-rich gas (50% H{sub 2}, 17% CO and 33% N{sub 2}, for partial oxidation/water shifting) can be efficiently made in compact plasma reformers. Experiments have been carried out in a small device (2--3 kW) and without the use of efficient heat regeneration. For partial oxidation/water shifting, it was determined that the specific energy consumption in the plasma reforming processes is 16 MJ/kg H{sub 2} with high conversion efficiencies. Larger plasmatrons, better reactor thermal insulation, efficient heat regeneration and improved plasma catalysis could also play a major role in specific energy consumption reduction and increasing the methane conversion. A system has been demonstrated for hydrogen production with low CO content ({approximately} 1.5%) with power densities of {approximately} 30 kW (H{sub 2} HHV)/liter of reactor, or {approximately} 10 m{sup 3}/hr H{sub 2} per liter of reactor. Power density should further increase with increased power and improved design.

  2. Eu{sup 3+} luminescence enhancement by intercalation of benzenepolycarboxylic guests into Eu{sup 3+}-doped layered gadolinium hydroxide

    SciTech Connect

    Gu, Qingyang; Pan, Guohua; Ma, Teng; Huang, Gailing; Sun, Genban; Ma, Shulan; Yang, Xiaojing

    2014-05-01

    Graphical abstract: Two benzenepolycarboxylic sensitizers, 1,3,5-benzenetricarboxylic acid (BTA) and 1,2,4,5-benzenetetracarboxylic acid (BA), were intercalated into NO{sub 3}–LGdH:Eu, in which different structures of the compounds resulted in varied arrangement in the gallery. The two organic compounds especially BA markedly enhanced the red luminescence of Eu{sup 3+} due to efficient energy transfer between the organic guests and Eu{sup 3+} centers. - Highlights: • We report the intercalation of benzenepolycarboxylic organic sensitizers into LRH. • We study the intercalation structure and the arrangement of the interlayer guests. • The two organic compounds can markedly enhance the luminescence of Eu{sup 3+}. • There exists efficient energy transfer between organic guests and Eu{sup 3+} centers. • This material opens a route for fabricating new multifunctional luminescent materials. - Abstract: Two benzenepolycarboxylic organic sensitizers, 1,3,5-benzenetricarboxylic acid (BTA) and 1,2,4,5-benzenetetracarboxylic acid (BA), were intercalated into the gallery of NO{sub 3}{sup −} type Eu{sup 3+}-doped layered gadolinium hydroxide (NO{sub 3}–LGdH:Eu). CHN analysis, FTIR, and SEM were employed to characterize the intercalation structures of the as-prepared organic/inorganic hybrids. The area per unit charge (S{sub charge}) was used to explain the intercalation structure and the arrangement of the interlayer guests. Different structures of the two organic compounds resulted in varied arrangement of guests. Photoluminescence studies indicated that both of the two organic compounds especially BA markedly enhanced the red luminescence of Eu{sup 3+} due to efficient energy transfer between the organic guests and Eu{sup 3+} centers.

  3. Hyper-stable organo-EuIII luminophore under high temperature for photo-industrial application

    PubMed Central

    Nakajima, Ayako; Nakanishi, Takayuki; Kitagawa, Yuichi; Seki, Tomohiro; Ito, Hajime; Fushimi, Koji; Hasegawa, Yasuchika

    2016-01-01

    Novel organo-EuIII luminophores, Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y (hfa: hexafluoroacetylacetonate, CPO: 4-carboxyphenyl diphenyl phosphine oxide, TCPO: 4,4′,4″-tricarboxyphenyl phosphine oxide), were synthesized by the complexation of EuIII ions with hfa moieties and CPO or TCPO ligands. The thermal and luminescent stabilities of the luminophores are extremely high. The decomposition temperature of Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y were determined as 200 and 450 °C, respectively. The luminescence of Eu(hfa)x(TCPO)y under UV light irradiation was observed even at a high temperature, 400 °C. The luminescent properties of Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y were estimated from emission spectra, quantum yields and lifetime measurements. The energy transfer efficiency from hfa moieties to EuIII ions in Eu(hfa)x(TCPO)y was 59%. The photosensitized luminescence of hyper-stable Eu(hfa)x(TCPO)y at 400 °C is demonstrated for future photonic applications. PMID:27074731

  4. Hyper-stable organo-EuIII luminophore under high temperature for photo-industrial application

    NASA Astrophysics Data System (ADS)

    Nakajima, Ayako; Nakanishi, Takayuki; Kitagawa, Yuichi; Seki, Tomohiro; Ito, Hajime; Fushimi, Koji; Hasegawa, Yasuchika

    2016-04-01

    Novel organo-EuIII luminophores, Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y (hfa: hexafluoroacetylacetonate, CPO: 4-carboxyphenyl diphenyl phosphine oxide, TCPO: 4,4‧,4″-tricarboxyphenyl phosphine oxide), were synthesized by the complexation of EuIII ions with hfa moieties and CPO or TCPO ligands. The thermal and luminescent stabilities of the luminophores are extremely high. The decomposition temperature of Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y were determined as 200 and 450 °C, respectively. The luminescence of Eu(hfa)x(TCPO)y under UV light irradiation was observed even at a high temperature, 400 °C. The luminescent properties of Eu(hfa)x(CPO)y and Eu(hfa)x(TCPO)y were estimated from emission spectra, quantum yields and lifetime measurements. The energy transfer efficiency from hfa moieties to EuIII ions in Eu(hfa)x(TCPO)y was 59%. The photosensitized luminescence of hyper-stable Eu(hfa)x(TCPO)y at 400 °C is demonstrated for future photonic applications.

  5. Antiferromagnetism in EuCu2As2 and EuCu1.82Sb2 single crystals

    DOE PAGESBeta

    Anand, V. K.; Johnston, D. C.

    2015-05-07

    Single crystals of EuCu2As2 and EuCu2Sb2 were grown from CuAs and CuSb self-flux, respectively. The crystallographic, magnetic, thermal, and electronic transport properties of the single crystals were investigated by room-temperature x-ray diffraction (XRD), magnetic susceptibility χ versus temperature T, isothermal magnetization M versus magnetic field H, specific heat Cp(T), and electrical resistivity ρ(T) measurements. EuCu2As2 crystallizes in the body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm), whereas EuCu2Sb2 crystallizes in the related primitive tetragonal CaBe2Ge2-type structure (space group P4/nmm). The energy-dispersive x-ray spectroscopy and XRD data for the EuCu2Sb2 crystals showed the presence of vacancies on the Cu sites, yielding themore » actual composition EuCu1.82Sb2. The ρ(T) and Cp(T) data reveal metallic character for both EuCu2As2 and EuCu1.82Sb2. Antiferromagnetic (AFM) ordering is indicated from the χ(T),Cp(T), and ρ(T) data for both EuCu2As2 (TN = 17.5 K) and EuCu1.82Sb2 (TN = 5.1 K). In EuCu1.82Sb2, the ordered-state χ(T) and M(H) data suggest either a collinear A-type AFM ordering of Eu+2 spins S = 7/2 or a planar noncollinear AFM structure, with the ordered moments oriented in the tetragonal ab plane in either case. This ordered-moment orientation for the A-type AFM is consistent with calculations with magnetic dipole interactions. As a result, the anisotropic χ(T) and isothermal M(H) data for EuCu2As2, also containing Eu+2 spins S = 7/2, strongly deviate from the predictions of molecular field theory for collinear AFM ordering and the AFM structure appears to be both noncollinear and noncoplanar.« less

  6. Antiferromagnetism in EuCu2As2 and EuCu1.82Sb2 single crystals

    NASA Astrophysics Data System (ADS)

    Anand, V. K.; Johnston, D. C.

    2015-05-01

    Single crystals of EuCu2As2 and EuCu2Sb2 were grown from CuAs and CuSb self-flux, respectively. The crystallographic, magnetic, thermal, and electronic transport properties of the single crystals were investigated by room-temperature x-ray diffraction (XRD), magnetic susceptibility χ versus temperature T , isothermal magnetization M versus magnetic field H , specific heat Cp(T ) , and electrical resistivity ρ (T ) measurements. EuCu2As2 crystallizes in the body-centered tetragonal ThCr2Si2 -type structure (space group I 4 /m m m ), whereas EuCu2Sb2 crystallizes in the related primitive tetragonal CaBe2Ge2 -type structure (space group P 4 /n m m ). The energy-dispersive x-ray spectroscopy and XRD data for the EuCu2Sb2 crystals showed the presence of vacancies on the Cu sites, yielding the actual composition EuCu1.82Sb2 . The ρ (T ) and Cp(T ) data reveal metallic character for both EuCu2As2 and EuCu1.82Sb2 . Antiferromagnetic (AFM) ordering is indicated from the χ (T ) ,Cp(T ) , and ρ (T ) data for both EuCu2As2 (TN=17.5 K) and EuCu1.82Sb2 (TN=5.1 K). In EuCu1.82Sb2 , the ordered-state χ (T ) and M (H ) data suggest either a collinear A-type AFM ordering of Eu+2 spins S =7/2 or a planar noncollinear AFM structure, with the ordered moments oriented in the tetragonal a b plane in either case. This ordered-moment orientation for the A-type AFM is consistent with calculations with magnetic dipole interactions. The anisotropic χ (T ) and isothermal M (H ) data for EuCu2As2 , also containing Eu+2 spins S =7/2 , strongly deviate from the predictions of molecular field theory for collinear AFM ordering and the AFM structure appears to be both noncollinear and noncoplanar.

  7. On the Road to Reform: A Sociocultural Interpretation of Reform

    ERIC Educational Resources Information Center

    Mensah, Felicia Moore

    2011-01-01

    In this paper I discuss how reform in science education is interpreted by Barma as she recounts the story of Catherine, a grade 9 biology teacher, who reforms her teaching practices in response to a national curriculum reform in Quebec, Canada. Unlike some cases in response to reform, this case is hopeful and positive. Also in this paper, I…

  8. Reforming Educational Reform: A Democratic Perspective

    NASA Astrophysics Data System (ADS)

    Green, J.

    2005-05-01

    This essay examines the status of educational reform in the United States as represented by the current Bush administration's program titled "No Child Left Behind" (NCLB). Employing the techniques of critical theory and logical analysis, contemporary reform efforts are compared with other, more progressive, educational reform movements in an effort to gain perspective and conceptual "traction" as it were, in differentiating such movements. Criteria are established for the assessment and evaluation of reform movements. These are employed in judging the efficacy of NCLB's aim, content, and methods, as well as the results of its program following four years of implementation. The merits of the centrality of standardized testing, pre-ordained curricular content, and exclusively didactic teaching methodologies are criticized, along with the extra-school societal forces which ordain these and determine their prominence in the NCLB program. The essentialism adopted by NCLB is, moreover, evaluated in the light of pragmatic, phenomenological, and postmodern educational theory. Arguing that the school is always and inevitably an instrument of societal forces, interests, and groups, it is contended that these not only be acknowledged, but that avenues be formalized for a thorough going and continuous educational "conversation," to borrow Rorty's term, for an amicable resolution of the issues of education's aim(s), content, and methods.

  9. New process model proves accurate in tests on catalytic reformer

    SciTech Connect

    Aguilar-Rodriguez, E.; Ancheyta-Juarez, J. )

    1994-07-25

    A mathematical model has been devised to represent the process that takes place in a fixed-bed, tubular, adiabatic catalytic reforming reactor. Since its development, the model has been applied to the simulation of a commercial semiregenerative reformer. The development of mass and energy balances for this reformer led to a model that predicts both concentration and temperature profiles along the reactor. A comparison of the model's results with experimental data illustrates its accuracy at predicting product profiles. Simple steps show how the model can be applied to simulate any fixed-bed catalytic reformer.

  10. Chicago School Reform as History.

    ERIC Educational Resources Information Center

    Katz, Michael B.

    1992-01-01

    Discusses the relationship between Chicago's school reform and history, noting implications for current reform: (1) origins of bureaucracy and ascendance of experts and professionals; (2) educational reform as a social movement; (3) race and ethnicity; (4) revitalization of the public sphere; and (5) limits of educational reform. (SM)

  11. Atuarfitsialak: Greenland's Cultural Compatible Reform

    ERIC Educational Resources Information Center

    Wyatt, Tasha R.

    2012-01-01

    In 2002, Greenlandic reform leaders launched a comprehensive, nation-wide reform to create culturally compatible education. Greenland's reform work spans the entire educational system and includes preschool through higher education. To assist their efforts, reform leaders adopted the Standards for Effective Pedagogy developed at the Center for…

  12. EU pharmaceutical expenditure forecast

    PubMed Central

    Urbinati, Duccio; Rémuzat, Cécile; Kornfeld, Åsa; Vataire, Anne-Lise; Cetinsoy, Laurent; Aballéa, Samuel; Mzoughi, Olfa; Toumi, Mondher

    2014-01-01

    Background and Objectives With constant incentives for healthcare payers to contain their pharmaceutical budgets, forecasting has become critically important. Some countries have, for instance, developed pharmaceutical horizon scanning units. The objective of this project was to build a model to assess the net effect of the entrance of new patented medicinal products versus medicinal products going off-patent, with a defined forecast horizon, on selected European Union (EU) Member States’ pharmaceutical budgets. This model took into account population ageing, as well as current and future country-specific pricing, reimbursement, and market access policies (the project was performed for the European Commission; see http://ec.europa.eu/health/healthcare/key_documents/index_en.htm). Method In order to have a representative heterogeneity of EU Member States, the following countries were selected for the analysis: France, Germany, Greece, Hungary, Poland, Portugal, and the United Kingdom. A forecasting period of 5 years (2012–2016) was chosen to assess the net pharmaceutical budget impact. A model for generics and biosimilars was developed for each country. The model estimated a separate and combined effect of the direct and indirect impacts of the patent cliff. A second model, estimating the sales development and the risk of development failure, was developed for new drugs. New drugs were reviewed individually to assess their clinical potential and translate it into commercial potential. The forecast was carried out according to three perspectives (healthcare public payer, society, and manufacturer), and several types of distribution chains (retail, hospital, and combined retail and hospital). Probabilistic and deterministic sensitivity analyses were carried out. Results According to the model, all countries experienced drug budget reductions except Poland (+€41 million). Savings were expected to be the highest in the United Kingdom (−€9,367 million), France

  13. Catalytic reforming methods

    DOEpatents

    Tadd, Andrew R; Schwank, Johannes

    2013-05-14

    A catalytic reforming method is disclosed herein. The method includes sequentially supplying a plurality of feedstocks of variable compositions to a reformer. The method further includes adding a respective predetermined co-reactant to each of the plurality of feedstocks to obtain a substantially constant output from the reformer for the plurality of feedstocks. The respective predetermined co-reactant is based on a C/H/O atomic composition for a respective one of the plurality of feedstocks and a predetermined C/H/O atomic composition for the substantially constant output.

  14. Non-catalytic recuperative reformer

    SciTech Connect

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  15. Enhanced luminescence in Eu-doped ZnO nanocrystalline films

    NASA Astrophysics Data System (ADS)

    Suzuki, Keigo; Murayama, Koji; Tanaka, Nobuhiko

    2015-07-01

    We found an enhancement of Eu3+ emissions in Eu-doped ZnO nanocrystalline films fabricated by microemulsion method. The Eu3+ emission intensities were increased by reducing annealing temperatures from 633 K to 533 K. One possible explanation for this phenomenon is that the size reduction enhances the energy transfer from ZnO nanoparticles to Eu3+ ions. Also, the shift of the charge-transfer band into the low-energy side of the absorption edge is found to be crucial, which seems to expedite the energy transfer from O atoms to Eu3+ ions. These findings will be useful for the material design of Eu-doped ZnO phosphors.

  16. Enhanced luminescence in Eu-doped ZnO nanocrystalline films

    SciTech Connect

    Suzuki, Keigo Murayama, Koji; Tanaka, Nobuhiko

    2015-07-20

    We found an enhancement of Eu{sup 3+} emissions in Eu-doped ZnO nanocrystalline films fabricated by microemulsion method. The Eu{sup 3+} emission intensities were increased by reducing annealing temperatures from 633 K to 533 K. One possible explanation for this phenomenon is that the size reduction enhances the energy transfer from ZnO nanoparticles to Eu{sup 3+} ions. Also, the shift of the charge-transfer band into the low-energy side of the absorption edge is found to be crucial, which seems to expedite the energy transfer from O atoms to Eu{sup 3+} ions. These findings will be useful for the material design of Eu-doped ZnO phosphors.

  17. Exploring growth conditions and Eu2+ concentration effects for KSr2I5:Eu scintillator crystals

    NASA Astrophysics Data System (ADS)

    Stand, L.; Zhuravleva, M.; Camarda, G.; Lindsey, A.; Johnson, J.; Hobbs, C.; Melcher, C. L.

    2016-04-01

    Our current research is focused on understanding dopant optimization, growth rate, homogeneity and their impact on the overall performance of KSr2I5:Eu2+ single crystal scintillators. In this work we have investigated the effects of Eu2+ concentration in the potassium strontium iodide matrix, and we found that the concentration needed to maximize the light yield was 4 mol%. In order to assess the effects of the pulling rate, we grew single crystals at 12, 24 and 120 mm/day via the vertical Bridgman technique. For the sample sizes measured (5×5×5 mm3), we found that the crystal grown at the fastest rate of 120 mm/day showed a light yield within ~7% of the more slowly grown boules, and no significant change was observed in the energy resolution. Therefore, light yields from 88,000 to 96,000 ph/MeV and energy resolutions from 2.4 to 3.0% (at 662 keV) were measured for KSr2I5:Eu 4% over a relatively wide range of growth conditions. In order to assess the homogeneity of KSr2I5:Eu 4%, a newly developed micro-resolution X-ray technique was used to map the light yield as a function of excitation position. In the crystals that we studied, we did not observe any significant inhomogeneity other than a smooth gradient due to light collection and self absorption effects.

  18. VET Reform Challenges for the Teaching Profession: A Lifelong Learning Perspective

    ERIC Educational Resources Information Center

    Buck, Bernhard

    2005-01-01

    The article addresses key challenges for the teaching profession, and corresponding institutions, to secure a prominent role in a VET reform, which is devoted to a lifelong learning perspective. These challenges may apply to EU countries but draw on the author's work in transition countries. The article clarifies the difficulties for vocational…

  19. Focus on Reform.

    ERIC Educational Resources Information Center

    Riggins, Cheryl G.

    2002-01-01

    Describes principal-initiated reform efforts at Alton Elementary School in downtown Memphis, Tennessee, that improved teacher performance and student reading scores. Alton is a K-4 school with a 100 percent African-American student population. (PKP)

  20. Eu2+ concentration effects in KCa0.8Sr0.2I3:Eu2+: A novel high-performance scintillator

    NASA Astrophysics Data System (ADS)

    Wu, Yuntao; Zhuravleva, Mariya; Lindsey, Adam C.; Koschan, Merry; Melcher, Charles L.

    2016-06-01

    We report here the effect of Eu2+ concentration in KCa0.8Sr0.2I3:Eu2+ single crystal scintillators. KCa0.8Sr0.2I3:Eu2+ single crystals doped with 0.5, 1, 3, 5, and 7 mol% Eu2+ were grown by the Bridgman method. The effects of varying Eu2+concentration and crystal volume on the scintillation properties, including light yield, energy resolution, nonproportionality, scintillation decay time and afterglow level, were systematically investigated. For 5 mm×5 mm×5 mm samples, the best light yield of 86,000±4000 photons/MeV was achieved with a content of 5 mol% Eu2+; its energy resolution of 2.5% at 662 keV was comparable to that of LaBr3:Ce3+ and SrI2:Eu2+. With larger samples of about 2.2 cm3, the best performances achieved were for 3 mol% Eu2+ concentration, i.e. a light yield of 76,000±4000 photons/MeV and an energy resolution of 3% at 662 keV. A direct correlation between nonproportionality and Eu2+ concentration was found. A continuous lengthening of scintillation decay time and x-ray induced afterglow level with increasing Eu2+ concentration was observed. The self-absorption effect was evaluated by using the Stokes shift and the temperature dependence of the photoluminescence decay (PL) of the Eu2+ centers. The sample with the highest dopant concentration had more severe temperature quenching of the Eu2+5d-4f emission than the sample with the lowest dopant concentration, which could be ascribed to the thermally activated concentration quenching.

  1. Reformer Fuel Injector

    NASA Technical Reports Server (NTRS)

    Suder, Jennifer L.

    2004-01-01

    Today's form of jet engine power comes from what is called a gas turbine engine. This engine is on average 14% efficient and emits great quantities of green house gas carbon dioxide and air pollutants, Le. nitrogen oxides and sulfur oxides. The alternate method being researched involves a reformer and a solid oxide fuel cell (SOFC). Reformers are becoming a popular area of research within the industry scale. NASA Glenn Research Center's approach is based on modifying the large aspects of industry reforming processes into a smaller jet fuel reformer. This process must not only be scaled down in size, but also decrease in weight and increase in efficiency. In comparison to today's method, the Jet A fuel reformer will be more efficient as well as reduce the amount of air pollutants discharged. The intent is to develop a 10kW process that can be used to satisfy the needs of commercial jet engines. Presently, commercial jets use Jet-A fuel, which is a kerosene based hydrocarbon fuel. Hydrocarbon fuels cannot be directly fed into a SOFC for the reason that the high temperature causes it to decompose into solid carbon and Hz. A reforming process converts fuel into hydrogen and supplies it to a fuel cell for power, as well as eliminating sulfur compounds. The SOFC produces electricity by converting H2 and CO2. The reformer contains a catalyst which is used to speed up the reaction rate and overall conversion. An outside company will perform a catalyst screening with our baseline Jet-A fuel to determine the most durable catalyst for this application. Our project team is focusing on the overall research of the reforming process. Eventually we will do a component evaluation on the different reformer designs and catalysts. The current status of the project is the completion of buildup in the test rig and check outs on all equipment and electronic signals to our data system. The objective is to test various reformer designs and catalysts in our test rig to determine the most

  2. Rapid and Energy-Saving Microwave-Assisted Solid-State Synthesis of Pr(3+)-, Eu(3+)-, or Tb(3+)-Doped Lu2O3 Persistent Luminescence Materials.

    PubMed

    Pedroso, Cássio C S; Carvalho, José M; Rodrigues, Lucas C V; Hölsä, Jorma; Brito, Hermi F

    2016-08-01

    Persistent luminescence materials Lu2O3:R(3+),M (Pr,Hf(IV); Eu; or Tb,Ca(2+)) were successfully and rapidly (22 min) prepared by microwave-assisted solid-state synthesis (MASS) using a carbon microwave susceptor and H3BO3 as flux. Reaction times are reduced by up to 93% over previous synthetic methods, without special gases application and using a domestic microwave oven. All materials prepared with H3BO3 flux exhibit LuBO3 impurities that were quantified by Rietveld refinement from synchrotron radiation X-ray powder diffraction patterns. The flux does not considerably affect the crystalline structure of the C-Lu2O3, however. Scanning electron micrographs suggest low surface area when H3BO3 flux is used in the materials' synthesis, decreasing the amount of surface hydroxyl groups in Lu2O3 and improving the luminescence intensity of the phosphors. The carbon used as the susceptor generates CO gas, leading to complete reduction of Tb(IV) to Tb(3+) and partial conversion of Pr(IV) to Pr(3+) present in the Tb4O7 and Pr6O11 precursors, as indicated by X-ray absorption near-edge structure data. Persistent luminescence spectra of the materials show the red/near-IR, reddish orange, and green emission colors assigned to the 4f(n) → 4f(n) transitions characteristics of Pr(3+), Eu(3+), and Tb(3+) ions, respectively. Differences between the UV-excited and persistent luminescence spectra can be explained by the preferential persistent luminescence emission of R(3+) ion in the S6 site rather than R(3+) in the C2 site. In addition, inclusion of Hf(IV) and Ca(2+) codopants in the Lu2O3 host increases the emission intensity and duration of persistent luminescence due to generation of traps caused by charge compensation in the lattice. Photonic materials prepared by MASS with H3BO3 flux show higher persistent luminescence performance than those prepared by the ceramic method or MASS without flux. Color tuning of persistent luminescence in Lu2O3:R(3+),M provides potential

  3. Luminescence properties of ZnS:Cu, Eu semiconductor nanocrystals synthesized by a hydrothermal process

    NASA Astrophysics Data System (ADS)

    Xin, Mei; Hu, Li-Zhong

    2013-08-01

    ZnS:Cu, Eu nanocrystals with an average diameter of ~ 80 nm are synthesized using a hydrothermal approach at 200 °C. The photoluminescence (PL) properties of the ZnS:Cu, Eu nanocrystals before and after annealing, as well as the doping form of Eu, are studied. The as-synthesized samples are characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, and the excitation and emission spectra (PL). The results show that both Cu and Eu are indeed incorporated into the ZnS matrix. Compared with the PL spectrum of the Cu mono-doped sample, the PL emission intensity of the Cu and Eu-codoped sample increases and a peak appears at 516 nm, indicating that Eu3+ ions, which act as an impurity compensator and activator, are incorporated into the ZnS matrix, forming a donor level. Compared with the unannealed sample, the annealed one has an increased PL emission intensity and the peak position has a blue shift of 56 nm from 516 nm to 460 nm, which means that Eu3+ ions reduce to Eu2+ ions, thereby leading to the appearance of Eu2+ characteristic emission and generating effective host-to-Eu2+ energy transfer. The results indicate the potential applications of ZnS:Cu, Eu nanoparticles in optoelectronic devices.

  4. Understanding the photoluminescence characteristics of Eu3+-doped double-perovskite by electronic structure calculation

    NASA Astrophysics Data System (ADS)

    Ghosh, Binita; Halder, Saswata; Das, Sayantani; Sinha, T. P.

    2016-05-01

    Europium-doped luminescent barium samarium tantalum oxide Ba2SmTaO6 (BST) has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BST and Eu-doped BST have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BST has been discussed. In the case of Eu-doped BST, there is an impurity energy band at the Fermi level, which is formed by seven spin up energy levels of Eu and act as the luminescent centre, which is evident from the band structure calculations.

  5. On the road to reform: a sociocultural interpretation of reform

    NASA Astrophysics Data System (ADS)

    Mensah, Felicia Moore

    2011-09-01

    In this paper I discuss how reform in science education is interpreted by Barma as she recounts the story of Catherine, a grade 9 biology teacher, who reforms her teaching practices in response to a national curriculum reform in Quebec, Canada. Unlike some cases in response to reform, this case is hopeful and positive. Also in this paper, I address some familiar areas that must be considered when teachers undertake curriculum reform and how science educators may fulfill the role of facilitator and advocate in the support of teachers on the road to reform. The commentary focuses on how Barma retells the story through the lens of activity theory.

  6. When Corruption Gets in the Way: Befriending Diaspora and EU-nionizing Bosnia's Higher Education

    ERIC Educational Resources Information Center

    Sabic-El-Rayess, Amra

    2013-01-01

    This article investigates the encounter of EU-unionization with a domesticated practice of corruption in Bosnian higher education. Relying on primary data collected in Bosnia's public higher education system, the study finds that the country's corrupt higher education is in conflict with the Bologna-themed reforms that would arguably…

  7. Cooperative Learning for Educational Reform in Armenia

    ERIC Educational Resources Information Center

    Hovhannisyan, Aleksan; Sahlberg, Pasi

    2010-01-01

    Armenia is in the midst of major educational reforms in which teacher professional development is a key component. Much of the energy devoted to developing education in Armenia is targeted towards enhancing student-centred teaching, especially cooperative learning. This has become a significant challenge for many schools and teachers as they cope…

  8. Publicity as an Instrument of Reform.

    ERIC Educational Resources Information Center

    Caudill, Susan

    Albert Einstein and the Emergency Committee of Atomic Scientists (ECAS) conducted a reform-based public communication campaign for the international control of atomic energy after the Second World War. The Committee raised funds and sought publicity for its proposed solution to the problem of war and the management of peace. Its solution was the…

  9. Temperature-dependent luminescent properties of Eu-Tb complexes synthesized in situ in gel glass

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Qian, Guodong; Wang, Zhiyu; Wang, Minquan

    2005-02-01

    The chelates of europium and terbium with hexafluoroacetylacetone (HFA) and triphenylphoshine oxide (TPPO), Eu /Tb(HFA)3(TPPO)2, have been synthesized in situ in gel glasses with various concentrations of Eu3+ and Tb3+ ions. The photoluminescence spectra have been measured and the characteristic transitions of Tb3+ and Eu3+ have been observed. Due to the variance of energy transfer efficiencies from Tb3+ to Eu3+, the intensity ratios of europium luminescent band to terbium band vary remarkably with measurement temperatures. In addition, the Förster mechanism has been proved to be responsible for the energy transfer between Eu3+ and Tb3+. The materials doped with Eu /Tb(HFA)3(TPPO)2 are promising for being used as a temperature detector and thermal-sensitive probe of optical fiber sensor.

  10. Antiferromagnetic Interlayer Exchange Coupling in All-Semiconducting EuS/PbS/EuS Trilayers

    NASA Technical Reports Server (NTRS)

    Smits, C. J. P.; Filip, A. T.; Swagten, H. J. M.; Koopmans, B.; deJonge, W. J. M.; Chernyshova, M.; Kowalczyk, L.; Grasza, K.; Szczerbakow, A.; Story, T.

    2003-01-01

    A comprehensive experimental study on the antiferromagnetic interlayer exchange coupling in high quality epitaxial all-semiconducting EuSPbSEuS trilayers is reported. The influence of substrates, the thickness of the non-magnetic PbS spacer layer, and of temperature, was investigated by means of SQUID magnetometry. In trilayers with a PbS thickness between 4 and 12 deg A the low temperature hysteresis loops showed the signature of antiferromagnetic coupling. The value of the interlayer exchange coupling energy was determined by simulating the data with a modified Stoner model, including Zeeman, anisotropy, and exchange coupling energies. An important observation was of a strong dependence of the interlayer exchange coupling energy on temperature, consistent with a power law dependence of the exchange coupling constant on the saturation magnetization of the EuS layers. While no theoretical description is readily available, we conjecture that the observed behavior is due to a dependence of the interlayer exchange coupling energy on the exchange splitting of the EuS conduction band.

  11. Biosimilar regulation in the EU.

    PubMed

    Kurki, Pekka; Ekman, Niklas

    2015-01-01

    In the EU, the EMA has been working with biosimilars since 1998. This experience is crystallized in the extensive set of guidelines, which range from basic principles to details of clinical trials. While the guidance may appear complicated, it has enabled the development of biosimilars, of which 21 have managed to get marketing authorization. Currently marketed biosimilars in the EU have a good track record in safety and traceability. No biosimilars have been withdrawn from the market because of safety concerns. The most controversial issues with biosimilars are immunogenicity and extrapolation of therapeutic indications. The available data for these topics do not raise concerns among EU regulators. Interchangeability and substitution are regulated by individual EU member states. PMID:26294076

  12. Differential scanning calorimetry investigations on Eu-doped fluorozirconate-based glass ceramics

    PubMed Central

    Paßlick, C.; Ahrens, B.; Henke, B.; Johnson, J. A.; Schweizer, S.

    2010-01-01

    The properties of Eu-doped fluorochlorozirconate (FCZ) glass ceramics upon thermal processing and the influence of Eu-doping on the formation of BaCl2 nanocrystals therein have been investigated. Differential scanning calorimetry indicates that higher Eu-doping shifts the crystallization peak of the nanocrystals in the glass to lower temperatures, while the glass transition temperature remains constant. The activation energy and the thermal stability parameters for the BaCl2 crystallization are determined. PMID:21286235

  13. [Eu ⊂ bpy·bpy·bpy] + cryptate: Luminescence and conformation

    NASA Astrophysics Data System (ADS)

    Blasse, G.; Dirksen, G. J.; van der Voort, D.; Sabbatini, N.; Perathoner, S.; Lehn, J.-M.; Alpha, B.

    1988-05-01

    The luminescence of [Eu ⊂ bpy·bpy·bpy] 3+ cryptate is reported for the solid (down to 4.2 K) and for molecules in porous glass. Energy transfer from the cryptand to Eu 3+ occurs with high efficiency. The emission spectra are used to evaluate the molecular conformation of the cryptate. The Eu 3+ ion appears to be off-centre.

  14. Ecuador's silent health reform.

    PubMed

    De Paepe, Pierre; Echeverría Tapia, Ramiro; Aguilar Santacruz, Edison; Unger, Jean-Pierre

    2012-01-01

    Health sector reform was implemented in many Latin American countries in the 1980s and 1990s, leading to reduced public expenditure on health, limitations on public provision for disease control, and a minimum package of services, with concomitant growth of the private sector. At first sight, Ecuador appeared to follow a different pattern: no formal reform was implemented, despite many plans to reform the Ministry of Health and social health insurance. The authors conducted an in-depth review and analysis of published and gray literature on the Ecuadorian health sector from 1990 onward. They found that although neoliberal reform of the health sector was not openly implemented, many of its typical elements are present: severe reduction of public budgets, "universal" health insurance with limited coverage for targeted groups, and contracting out to private providers. The health sector remains segmented and fragmented, explaining the population's poor health status. The leftist Correa government has prepared an excellent long-term plan to unite services of the Ministry of Health and social security, but implementation is extremely slow. In conclusion, the health sector in Ecuador suffered a "silent" neoliberal reform. President Correa's progressive government intends to reverse this, increasing public budgets for health, but hesitates to introduce needed radical changes. PMID:22611652

  15. Radiation stability of CsBr:Eu needle image plates

    SciTech Connect

    Batentschuk, M.; Neudert, S.; Weidner, M.; Osvet, A.; Struye, L.; Tahon, J.-P.; Leblans, P.

    2009-10-15

    Needle image plates (NIPs) based on CsBr:Eu are a good alternative to the BaFBr:Eu powder image plates due to their higher sensitivity and improved spatial resolution. The x-ray radiation stability of the NIPs produced by Agfa Gevaert was investigated and it was found that the radiation stability of the optimized NIPs is as high as that of the commercial CsI:Tl single crystals and much higher than reported in literature for the CsBr:Eu NIPs. The dependence of the sensitivity of the NIPs on the accumulated dose was determined for three different types of x-ray irradiation. It is shown that degradation of the sensitivity starts at about 10 Gy and it is the strongest for the most hard x-ray beam. If the energy absorbed by a NIP is taken into account, the degradation does not depend on the hardness of the applied x-ray beam. It is suggested that the main reason for the observed high radiation stability of the CsBr:Eu NIPs is the use of the oxygen-free Eu{sup 2+}-containing precursor CsEuBr{sub 3} for the doping in the manufacturing process.

  16. Optical Study of Archetypical Valence-Fluctuating Eu Systems

    NASA Astrophysics Data System (ADS)

    Guritanu, V.; Seiro, S.; Sichelschmidt, J.; Caroca-Canales, N.; Iizuka, T.; Kimura, S.; Geibel, C.; Steglich, F.

    2012-12-01

    We have investigated the optical conductivity of the prominent valence-fluctuating compounds EuIr2Si2 and EuNi2P2 in the infrared energy range to get new insights into the electronic properties of valence-fluctuating systems. For both compounds, we observe upon cooling the formation of a renormalized Drude response, a partial suppression of the optical conductivity below 100meV, and the appearance of a midinfrared peak at 0.15eV for EuIr2Si2 and 0.13 eV for EuNi2P2. Most remarkably, our results show a strong similarity with the optical spectra reported for many Ce- or Yb-based heavy-fermion metals and intermediate valence systems, although the phase diagrams and the temperature dependence of the valence differ strongly between Eu systems and Ce- or Yb-based systems. This suggests that the hybridization between 4f and conduction electrons, which is responsible for the properties of Ce and Yb systems, plays an important role in valence-fluctuating Eu systems.

  17. Optically induced magnetic polarons in EuTe

    SciTech Connect

    Henriques, A. B.; Galgano, G. D.; Abramof, E.; Rappl, P. H. O.

    2013-12-04

    Direct measurements of the photoinduced magnetization in EuTe, using a two color pump-and-probe technique, are presented. The photoinduced effect was pumped using photons of above-the-bandgap energy, and detected by the Faraday rotation of a probe beam of energy below-the-bandgap. The photoinduced Faraday rotation changes sign, as expected from our model for the optically induced magnetic polaron. The EuTe spin-flop transition at low fields is also detected as a sharp step in the photoinduced Faraday rotation, and its observation provides additional supports for the photoinduced polaron model.

  18. Comprehensive Solutions for Urban Reform

    ERIC Educational Resources Information Center

    Kilgore, Sally

    2005-01-01

    The comprehensive school reform (CSR) models build consistency throughout a district while addressing the needs of individual schools. The high-quality CSR programs offer a most effective option for urban education reform.

  19. Boron induced change of the Eu valence state in EuPd3Bx (0≤x≤0.53) : A theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Gumeniuk, R.; Schmitt, M.; Loison, C.; Carrillo-Cabrera, W.; Burkhardt, U.; Auffermann, G.; Schmidt, M.; Schnelle, W.; Geibel, C.; Leithe-Jasper, A.; Rosner, H.

    2010-12-01

    A valence instability of Eu in EuPd3Bx (0≤x≤1) was discussed controversially in the past. In a joint theoretical and experimental study we investigate a large series of EuPd3Bx and GdPd3Bx compounds. Characterization by x-ray diffraction, metallography, energy-, and wavelength-dispersive x-ray spectroscopy as well as chemical analysis determine an existence range of EuPd3Bx up to x≤0.53 and x≤0.42 for the GdPd3Bx compounds, respectively. Our density-functional-based electronic structure calculation predict a valence change in EuPd3Bx above xcDFT=0.19±0.02 from a nonmagnetic Eu3+ state into a magnetic Eu2+ state which is reflected in a discontinuity of the lattice parameter. In contrast, the related Gd compounds with a stable Gd3+ state exhibit an almost linear behavior of the lattice parameter following Vegard’s law. Consistent with the calculations, the x-ray diffraction data show a kink in the lattice parameter for EuPd3Bx at xcXRD=0.22±0.02 . X-ray absorption spectroscopy measurements assign this kink to a transition into a heterogeneous mixed valence state for Eu with a critical B content xcXAS=0.22±0.03 . The observed change in the mean Eu valence from Eu3+ (x≤0.2) toward Eu2.5+ (x=0.5) is supported by magnetic susceptibility and specific-heat data.

  20. The Effects of Educational Reform

    ERIC Educational Resources Information Center

    Vasquez-Martinez, Claudio-Rafael; Giron, Graciela; De-La-Luz-Arellano, Ivan; Ayon-Bañuelos, Antonio

    2013-01-01

    Educational reform implies questions of social production and of state regulation that are the key words in educational reform, education and educational policies. These reforms are always on the political agenda of countries and involve international organisms, since education is a vehicle of development for social progress. A point of departure…

  1. Teacher Education Reforms in Albania.

    ERIC Educational Resources Information Center

    Whitehead, Joan

    2000-01-01

    Drawing on insights from Albanian teacher educators and government representatives, this paper examines processes of change and types of reform (modernization, structural, and systemic reform) in Albania. It also discusses the initial implementation of one of the reforms, which was directed at the balance and role of school experiences, analyzing…

  2. Kudzu, Rabbits, and School Reform.

    ERIC Educational Resources Information Center

    Goodlad, John I.

    2002-01-01

    Essay on school reform argues that quality teachers are key to successful reform, not reform rhetoric by state governors and U.S. Presidents. Asserts that primary mission of schooling is to provide students an educational apprenticeship in democracy. Qualified, caring, competent teachers are essential to accomplish this mission. (PKP)

  3. Globalization, Citizenship and Educational Reform

    ERIC Educational Resources Information Center

    Qi, Jie

    2009-01-01

    This paper explores the notions of globalization as embodied in Japanese educational reforms during the 1980s and 1990s. Modern institutional discourses of educational reform in Japan have shifted over time and all of these reform movements have been constructed by particular social and historical trajectories. Generally speaking, it has been…

  4. Prospects for Health Care Reform.

    ERIC Educational Resources Information Center

    Kastner, Theodore

    1992-01-01

    This editorial reviews areas of health care reform including managed health care, diagnosis-related groups, and the Resource-Based Relative Value Scale for physician services. Relevance of such reforms to people with developmental disabilities is considered. Much needed insurance reform is not thought to be likely, however. (DB)

  5. BaBrI:Eu2 + , a new bright scintillator

    SciTech Connect

    Bourret-Courchesne, E.D.; Bizarri, G.; Hanrahan, S.M.; Gundiah, G.; Yan, Z.; Derenzo, S.E.

    2009-11-07

    The scintillation properties of BaBrI:Eu2+ are reported. Crystals were produced by the vertical Bridgman technique in a sealed quartz ampoule. Excellent scintillation properties were measured. A light yield of 81,0007 +- 3000 photons per MeV (ph/MeV) of absorbed gamma-ray energy was measured. An energy resolution (FWHM over peak position) of 4.870.5percent was observed for the 662keV full absorption peak. Pulsed X-ray luminescence measurements show two exponential decay components of 297 and 482 ns with a contribution to the total light output of 23percent and 77percent, respectively. Under X-ray and UV excitation, the emission corresponds to a broadband center at 413 nm. These initial values make BaBrI:Eu2+ one of the brightest and the fastest known Eu2+ doped scintillators.

  6. Reforming the Undergraduate Experience

    ERIC Educational Resources Information Center

    VanderPol, Diane; Brown, Jeanne M.; Iannuzzi, Patricia

    2008-01-01

    The higher education literature abounds with reports and studies calling for reform in undergraduate education. An alphabet soup of higher education associations creates or advocates desired learning outcomes for postsecondary education and endorses approaches for student learning. This article shows connections between some of the major…

  7. Reforming Teacher Pay

    ERIC Educational Resources Information Center

    Burns, Susan Freeman; Gardner, Catherine D.

    2010-01-01

    A recent Google search for information regarding performance pay in education produced 6.1 million results. This number should come as no surprise given the current level of interest in incentives as a popular reform option in public education. Supporters believe pay-for-performance programs encourage less effective teachers to improve and will…

  8. Children and Welfare Reform.

    ERIC Educational Resources Information Center

    Behrman, Richard E., Ed.

    2002-01-01

    This issue of "The Future of Children" examines whether programs implemented by the federal welfare reform law accomplished the goal of reducing the number of children growing up in poor, single-parent families and whether these programs benefited children. This examination coincides with debates in Congress on the reauthorization of the Personal…

  9. Teenagers and Welfare Reform.

    ERIC Educational Resources Information Center

    Offner, Paul

    This report examines the extent to which welfare reform is changing adolescent behaviors that lead to welfare dependency. It begins by discussing the provisions in the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 that require teenagers to stay in school and live with a parent, concluding that relatively little can be…

  10. The Reform Game.

    ERIC Educational Resources Information Center

    Whitlock, Kelli

    2001-01-01

    A 3-year study of welfare reform in Ohio's 29 Appalachian counties surveyed human services agencies, county commissioners, poor families, and employers and found that rural barriers to employment included lack of jobs, lack of child care, poor health, lack of education and job skills, and transportation problems. Many former welfare recipients…

  11. Welfare Reform and Health

    ERIC Educational Resources Information Center

    Bitler, Marianne P.; Gelback, Jonah B.; Hoynes, Hilary W.

    2005-01-01

    A study of the effect of state and federal welfare reforms over the period 1990-2000 on health insurance coverage and healthcare utilization by single women aged between 20-45 is presented. It is observed that Personal Responsibility and Work Opportunity Act of 1996 which replaced the Aid to Families with Dependent Children program of 1990s with…

  12. Examining Comprehensive School Reform

    ERIC Educational Resources Information Center

    Aladjem, Daniel K., Ed.; Borman, Kathryn M., Ed.

    2006-01-01

    Urban school reformers for decades have tried to improve educational outcomes for underserved and disadvantaged students, with the assistance of constantly evolving federal and state policies. In recent years, education policies have shifted from targeting individual students to developing universal standards for teaching and learning, and…

  13. Accomplishing Districtwide Reform

    ERIC Educational Resources Information Center

    Sharratt, Lyn; Fullan, Michael

    2006-01-01

    This is a mystery story. It is about a district that apparently did the right things but seemed not to get commensurate results across all classrooms and schools. In this article, we look closely at the details and discover an important lesson about districtwide reform. The district is York Region District School Board, which is a large…

  14. Reform on the Move

    ERIC Educational Resources Information Center

    Clark, Janet; Otte, Michelle; Fair, Lynn

    2006-01-01

    Aurora (Colorado) Public Schools responded to the Colorado State Model Content Standards for Reading and Writing and the accountability measures attached to the state assessments by implementing the Aurora Achievement Initiative in 2001. Originating from literature on best practices and large-scale school reform, the goal of the districtwide…

  15. Welfare Reform Briefing Book.

    ERIC Educational Resources Information Center

    Children's Defense Fund, Washington, DC.

    This report presents information on the Aid to Families with Dependent Children (AFDC) program in light of efforts at welfare reform. Following a listing of whom to call at the Children's Defense Fund (CDF) regarding various welfare issues, the report's first section, "Basic Facts on Welfare," presents information on the AFDC in a…

  16. Reform in Canadian Universities.

    ERIC Educational Resources Information Center

    Small, J. M.

    1994-01-01

    A survey of 67 Canadian university vice presidents and 66 deans concerning reform in recent years found that the many changes reported were modest and reactive rather than bold and proactive. Most common changes involved strategic planning, retrenchment, curriculum expansion, response to enrollment changes, administrative restructuring, and more…

  17. Scaling up Education Reform

    ERIC Educational Resources Information Center

    Gaffney, Jon D. H.; Richards, Evan; Kustusch, Mary Bridget; Ding, Lin; Beichner, Robert J.

    2008-01-01

    The SCALE-UP (Student-Centered Activities for Large Enrollment for Undergraduate Programs) project was developed to implement reforms designed for small classes into large physics classes. Over 50 schools across the country, ranging from Wake Technical Community College to Massachusetts Institute of Technology (MIT), have adopted it for classes of…

  18. Reforming Underperforming High Schools

    ERIC Educational Resources Information Center

    MDRC, 2013

    2013-01-01

    Urban high schools are in trouble--high dropout rates, low student academic achievement, and graduates who are unprepared for college are just some of the disappointing indicators. However, recent research points to a select number of approaches to improving student outcomes and reforming underperforming schools--from particular ways of creating…

  19. Comprehensive School Reform.

    ERIC Educational Resources Information Center

    Hertling, Elizabeth

    2000-01-01

    This issue reviews publications that provide school leaders with guidance in determining how to choose and implement the schoolwide program that is best for their school. American Institutes for Research's "An Educator's Guide to Schoolwide Reform" provides educators with comprehensive profiles and evaluations of 24 of the leading schoolwide…

  20. Gamma-Ray Measurement of 152Eu Produced by Neutrons from the Hiroshima Atomic Bomb and Evaluation of Neutron Fluence

    NASA Astrophysics Data System (ADS)

    Kato, Kazuo; Habara, Minoru; Aoyama, Tetsuhisa; Sakata, Hidefumi; Yoshizawa, Yasukazu

    1990-08-01

    The 152Eu/Eu ratios were measured in a tombstone exposed to neutrons of the Hiroshima atomic bomb near the hypocenter. Measurements of 152Eu gamma rays were performed for europium samples chemically isolated from numerous rock specimens taken from the tombstone. A reliable attenuation curve of the 152Eu/Eu ratios was obtained. The curve suggests that the thermal neutron component was relatively small and the average incident angle of neutrons to the tombstone was roughly 45° from the perpendicular downward direction. It revealed to us several important pieces of information concerning the energy and angular distributions near the Hiroshima bomb hypocenter.

  1. Dry reforming of hydrocarbon feedstocks

    SciTech Connect

    Shah, Yatish T.; Gardner, Todd H.

    2014-09-25

    Developments in catalyst technology for the dry reforming of hydrocarbon feedstocks are reviewed for methane, higher hydrocarbons and alcohols. Thermodynamics, mechanisms and the kinetics of dry reforming are also reviewed. The literature on Ni catalysts, bi-metallic Ni catalysts and the role of promoters on Ni catalysts is critically evaluated. The use of noble and transitional metal catalysts for dry reforming is discussed. The application of solid oxide and metal carbide catalysts to dry reforming is also evaluated. Finally, various mechanisms for catalyst deactivation are assessed. This review also examines the various process related issues associated with dry reforming such as its application and heat optimization. Novel approaches such as supercritical dry reforming and microwave assisted dry reforming are briefly expanded upon.

  2. L-shell X-ray production cross sections of Ce, Nd, Sm, Eu, Gd, and Dy by impact of 14N2+ ions with energies between 7.0 MeV and 10.5 MeV

    NASA Astrophysics Data System (ADS)

    Murillo, G.; Méndez, B.; López-Monroy, J.; Miranda, J.; Villaseñor, P.

    2016-09-01

    L-shell X-ray production cross sections from the lanthanoid elements Ce, Nd, Sm, Eu, Gd, and Dy, induced by the impact of 14N2+ ions with energies in the interval 7.0 MeV to 10.5 MeV (0.50 MeV/μ to 0.75 MeV/μ), were measured and then compared with theoretical calculations obtained with the ECPSSR model with exact limits of integration (eCPSSR) and related corrections. These include the electron capture by the incoming ion and multiple ionizations of higher shells. Data from this work were contrasted with previously published L X-ray production cross sections for 14N2+ ion impact. As with other ions, a universal behavior is found when Lα and Lγ X-ray production cross sections are plotted as a function of reduced velocity parameters. The agreement with theoretical predictions was very good when the corrections were applied to the eCPSSR model.

  3. EU Space Awareness: Initial implemenation

    NASA Astrophysics Data System (ADS)

    Russo, Pedro

    2015-08-01

    EU Space Awareness uses the excitement of space to attract young people into science and technology and stimulate European and global citizenship. The project will show children and teenagers the opportunities offered by space science and engineering and inspire primary-school children when their curiosity is high and their value systems are being formed. EU Space Awareness, a 3-year project, has started in March 2015 with 10 partner organisations and 15 network nodes in 17 European countries and the IAU Office of Astronomy for Development. During this talk we will give a update about the intial implementation of the project and its relevant for astronomy for development.

  4. Probing dual mode emission of Eu3+ in garnet phosphor

    NASA Astrophysics Data System (ADS)

    Singh, S. K.; Gi Lee, Dong; Soo Yi, Soung; Jang, Kiwan; Shin, Dong-Soo; Hyun Jeong, Jung

    2013-05-01

    Eu3+ doped and Eu3+, Yb3+ co-doped Gd3Ga5O12 phosphors have been developed by facile solid state reaction method which can be easily scaled-up in large quantity. The synthesis has been optimized to get a single phase material at 1300 °C. The phase and crystal parameters have been analyzed by using X-ray diffraction measurement. Photoluminescence excitation (monitored for the 5D0 → 7F1 transition of Eu3+) depicts that the active ion (Eu3+) can be excited through direct excitation into 4f band of Eu3+, through charge transfer band (Eu3+-O2-) excitation and also through the excitation into 8S7/2 → 6IJ intra f-f transition of Gd3+ ion, which significantly all together cover a broad excitation region in 200-420 nm. In addition, in the presence of Yb3+ ions, the emission is also achieved by near infrared excitation (976 nm), through a typical upconversion (UC) process. Thus, the material efficiently behaves as a dual mode emitting phosphor (emission is achieved both through normal fluorescence and through UC process). The conversion efficiency of silicon solar cells is only 15% of terrestrial solar energy for 200-400 nm region and also the sub-band gap energy (in infrared region) is lost as heat; therefore, this kind of dual mode phosphors may be used to overcome the above mentioned incomplete utilization of the solar spectrum and can open realm of new possibilities for energy harvesting.

  5. Blue emission of Eu2+-doped translucent alumina

    DOE PAGESBeta

    Yang, Yan; Zhang, Lihua; Kisslinger, Kim; Wei, Hua; Melcher, Charles L.; Wu, Yiquan

    2015-08-21

    Inorganic scintillators are very important in medical and industrial measuring systems in the detection and measurement of ionizing radiation. In addition to Ce3+, a widely used dopant ion in oxide scintillators, divalent Europium (Eu2+) has shown promise as a high-luminescence, fast-response luminescence center useful in the detection of ionizing radiation. In this research, aluminum oxide (Al2O3) was studied as a host material for the divalent europium ion. Polycrystalline samples of Eu2+-doped translucent Al2O3 were fabricated, and room temperature luminescence behavior was observed. Al2O3 ceramics doped with 0.1 at% Eu2+ were fabricated with a relative density of 99.75% theoretical density andmore » in-line transmittance of 22% at a wavelength of 800 nm. The ceramics were processed by a gel-casting method, followed by sintering under high vacuum. The gelling agent, a copolymer of isobutylene and maleic anhydride, is marketed under the commercial name ISOBAM, and has the advantage of simultaneously acting as both a gelling agent and as a dispersant. The microstructure and composition of the vacuum-sintered Eu2+:Al2O3 were characterized by Scanning Electric Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy-dispersive X-ray spectroscopy (EDS). The phase composition was determined by X-ray diffraction measurements (XRD) combined with Rietveld analysis. The photoluminescence behavior of the Eu2+:Al2O3 was characterized using UV light as the excitation source, which emitted blue emission at 440 nm. The radio-luminescence of Eu2+:Al2O3 was investigated by illumination with X-ray radiation, showing three emission bands at 376 nm, 575 nm and 698 nm. Furthermore, multiple level traps at different depths were detected in the Eu2+:Al2O3 by employing thermoluminescence measurements.« less

  6. EU Regulations Impede Market Introduction of GM Forest Trees.

    PubMed

    Custers, René; Bartsch, Detlef; Fladung, Matthias; Nilsson, Ove; Pilate, Gilles; Sweet, Jeremy; Boerjan, Wout

    2016-04-01

    Biotechnology can greatly improve the efficiency of forest tree breeding for the production of biomass, energy, and materials. However, EU regulations impede the market introduction of genetically modified (GM) trees so their socioeconomic and environmental benefits are not realized. European policy makers should concentrate on a science-based regulatory process. PMID:26897457

  7. Photoluminescence in CaWO4:Bi3+, Eu3+ Material

    NASA Astrophysics Data System (ADS)

    Pode, R. B.; Dhoble, S. J.

    1997-10-01

    Luminescence of Bi3+ and Bi3+ + Eu3+ in calcium tungstate powder prepared by the solid state diffusion method has been reported. The excitation and emission bands in CaWO4 and CaWO4:Bi3+ coincide and appear at 256 and 430.5 nm, respectively. The 430.5 nm emission band is ten times stronger in the latter case (for 1 mol% Bi3+) than in the former case. The Eu3+ emission was observed at 619 nm in CaWO4:Eu3+<$> (1 mol%). The Eu3+ emission intensity increased significantly (about 37 times) with the addition of a small amount of Bi3+. The emission band of Bi3+ overlaps with the excitation band of Eu3+, resulting in a very efficient energy transfer from Bi3+ to Eu3+. The energy transfer probability is strongly dependent upon the Bi3+ concentration, with a maximum for 0.5 mol% of Bi3+ and drastically decreases for higher concentration. The mechanism of the energy transfer from Bi3+ to Eu3+ has been discussed. The CaWO4:(Bi3+, Eu3+) material is proposed as an efficient red phosphor.

  8. Thermal and optical properties of Tb(III), Eu(III) and Tb(III)/Eu(III) co-complexed silicone fluorinated acrylate copolymer

    NASA Astrophysics Data System (ADS)

    Zhai, Yinfeng; Xie, Hongde; Cai, Haijun; Cai, Peiqing; Seo, Hyo Jin

    2015-07-01

    Tb(III), Eu(III) and Tb(III)/Eu(III) activated silicone fluorinated acrylate (SFA) have been successfully synthesized using the method of semi-continuous emulsion polymerization. The copolymers are characterized by flourier transform infrared (FT-IR), thermal gravity analysis (TGA), photoluminescence excitation (PLE) and emission (PL) spectroscopy. The copolymer containing Tb(III) and Eu(III) ions display green and red luminescent colors under UV light excitation, respectively. The TGA curves show the thermal decomposition temperatures of the copolymers are up to about 300 °C. The PL spectra show a strong green emission at 546 nm (5D4 → 7F5) of Tb(III) complexed copolymers, and show a prominent red emission at 615 nm (5D0 → 7F2) of Eu(III) complexed copolymers. Different concentrations of Eu(III) and Tb(III) ions are introduced into the copolymer and the energy transfer from Tb(III) to Eu(III) ions in the copolymer was found. Thus, based on the results it can be suggested that SFA:Eu(III), SFA:Tb(III) and SFA:Tb(III)/Eu(III) can be used potentially as luminescent materials.

  9. Application of Eu2O3/ZnO nanoparticles in dye sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Kaur, Manveen; Verma, N. K.

    2013-06-01

    The synthesis of ZnO, Eu2O3 coated ZnO nanoparticles and their application in dye sensitized solar cells (DSSCs) has been reported. The synthesized samples have been characterized by XRD and the diffraction of crystal plane (222) of Eu2O3 was detected, demonstrating the existence of Eu2O3 on the surface of ZnO3, which has also been verified through EDAX. Compared to ZnO electrodes, Eu2O3 coated ZnO electrodes adsorbed more dye. Eu2O3 coating on ZnO forms an energy barrier, which suppresses the charge recombination. Consequently, the photoelectrochemical properties of the modified electrodes improved and the overall energy conversion efficiency η increased from 0.21% to 0.61% under the illumination of simulated light of 100mW/cm2.

  10. Synthesis and Fluorescence Properties of Eu(3+), Tb(3+) Complexes with Schiff Base Derivatives.

    PubMed

    Liu, Yanhong; Kong, Weihua; Yang, Zehui; Dai, Ming; Shi, Ling; Guo, Dongcai

    2016-03-01

    Novel Schiff base ligands derived from N'-benzylidene-benzohydrazide (substituted by -H, -CH3, -OCH3, -Cl) and 2-chloro-N-phenylacetamide were synthesized. The solid complexes of rare earth (Eu, Tb) nitrate with these Schiff base ligands were synthesized and characterized by elemental analysis, EDTA titrimetric analysis, thermal analysis, infrared spectra and UV-Vis spectra analysis. The fluorescence properties of rare earth (Eu, Tb) complexes in solid were studied. Under the excitation of ultraviolet light, these complexes exhibited characteristic emission of europium and terbium ions. The results showed that the ligand favored energy transfer to the emitting energy of Eu and Tb ions. Effects of different ligands on the fluorescence intensity of rare earth (Eu, Tb) complexes had been discussed. The electrochemical properties of rare earth (Eu, Tb) complexes were also investigated. PMID:26658796

  11. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-17

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  12. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    1999-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  13. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    2001-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  14. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-24

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  15. Multifuel reformer R D

    SciTech Connect

    Kumar, R.; Ahmed, S.

    1991-01-01

    The on-board fuel for fuel cell powered vehicles may be one or more of hydrogen, methanol, ethanol, natural gas, propane, or other liquified petroleum gases. To use hydrogen as the fuel, suitable means of storing, and subsequently delivering, adequate quantities of the gas must be developed. For all other fuels suitable reformers must be developed to convert the fuel to hydrogen or a hydrogen-rich gas mixture at rates corresponding to the varying power demand rates of the automotive system; this is especially true for the lower temperature fuel cells, such as the polymer electrolyte fuel cell which operates at 80{degrees}C and the phosphoric acid fuel cell which operates at 190{degrees}C. This paper discusses the key design and performance characteristics of such hydrogen storage and fuel reformer systems for use in stand-alone fuel cell automotive applications.

  16. Photoluminescence of Eu³⁺-doped glasses with Cu²⁺ impurities.

    PubMed

    Jiménez, José A

    2015-06-15

    Glasses activated with Eu(3+) ions are attractive as luminescent materials for various photonic applications. Co-doping with copper has been proposed for enhancing material optical properties, but the quenching effect of Cu(2+) impurities on Eu(3+) emission in glass remains largely unexplored. In this work, Eu2O3/CuO-containing barium-phosphate glasses have been prepared by the melt-quench method, and the Eu(3+) photoluminescence (PL) quenching resulting from Eu(3+)→Cu(2+) energy transfer was evaluated. Optical absorption spectroscopy showed that with the increase in CuO concentration the Cu(2+) absorption band resonant with Eu(3+) emission (e.g. (5)D0→(7)F2 transition around 615 nm) developed steadily. As a result, Eu(3+) PL was progressively quenched. Evaluation of the quenching constants as a function of temperature in the 298-673K range showed differences basically within experimental error, consistent with a resonant transfer and lack of phonon-assisted processes. Moreover, analysis of the Eu(3+) emission decay dynamics revealed a strong correlation between the decay rates and Cu(2+) impurity levels. Results imply that for practical applications the levels of Cu(2+) in Eu(3+)/Cu(+)-activated glasses should be reduced if not removed as these will significantly limit device efficiency. PMID:25797222

  17. Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Wei, Junchao

    2012-10-01

    The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from 5D0-7FJ transition (J = 1, 2) of Eu3+ markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

  18. Catalytic reforming catalyst

    SciTech Connect

    Buss, W.C.; Kluksdahl, H.E.

    1980-12-09

    An improved catalyst, having a reduced fouling rate when used in a catalytic reforming process, said catalyst comprising platinum disposed on an alumina support wherein the alumina support is obtained by removing water from aluminum hydroxide produced as a by-product from a ziegler higher alcohol synthesis reaction, and wherein the alumina is calcined at a temperature of 1100-1400/sup 0/F so as to have a surface area of 165 to 215 square meters per gram.

  19. Structural coupling across the direct EuO/Si interface

    NASA Astrophysics Data System (ADS)

    Averyanov, Dmitry V.; Tokmachev, Andrey M.; Likhachev, Igor A.; Lobanovich, Eduard F.; Parfenov, Oleg E.; Pashaev, Elkhan M.; Sadofyev, Yuri G.; Subbotin, Ilia A.; Yakunin, Sergey N.; Storchak, Vyacheslav G.

    2016-01-01

    The ferromagnetic semiconductor EuO is believed to be an effective spin injector when directly integrated with silicon (Si). Injection through spin-selective ohmic contact requires superb structural quality of the interface EuO/Si. A recent breakthrough in manufacturing free-of-buffer-layer EuO/Si junctions calls for structural studies of the interface between the semiconductors. The synthesis of EuO employs an advanced protection of the Si substrate surface and a two-step growth protocol. It prevents unwanted chemical reactions at the interface. Ex situ high-resolution x-ray diffraction (XRD) and reflectivity (XRR) accompanied by in situ reflection high-energy electron diffraction reveal direct coupling at the interface. A combined analysis of XRD and XRR data provides a common structural model. The structural quality of the EuO/Si spin contact far exceeds that of previous reports and thus makes a step forward to the ultimate goals of spintronics.

  20. Growth of EuO/Si and EuO/SrO/Si heteroepitaxial structures by molecular-beam epitaxy

    SciTech Connect

    Teterin, P. E. Averyanov, D. V.; Sadofyev, Yu. G. Parfenov, O. E.; Likhachev, I. A.; Storchak, V. G.

    2015-01-15

    Epitaxial EuO thin films with thickness up to 60 nm have been grown by molecular beam epitaxy both on SrO sublayers and directly on Si (001) substrates. Crystal structure has been controlled in situ by reflection high energy electron diffraction. Ex situ studies by X-ray diffraction and Rutherford backscattering have confirmed high crystalline quality of the films.

  1. Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

    NASA Astrophysics Data System (ADS)

    Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

    2016-05-01

    TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

  2. Concentration effect of H/OH and Eu{sup 3+} species on activating photoluminescence from ZnO:Eu{sup 3+} thin films

    SciTech Connect

    Akazawa, Housei; Shinojima, Hiroyuki

    2013-10-21

    We identified the conditions necessary for photoluminescence from Eu{sup 3+} ions doped in ZnO thin films to occur via indirect excitation of ZnO host crystal with a 325-nm laser light. The ZnO:Eu films were sputter-deposited on Si(100) substrates at room temperature with H{sub 2}O vapor flowing as the oxygen source gas. A very narrow emission peak at 612 nm, assigned to {sup 5}D{sub 0}−{sup 7}F{sub 2} transition of Eu{sup 3+} ions, appeared after annealing at 200–300 °C in a vacuum or at 500 °C in an O{sub 2} ambient. At temperatures higher than these, the 612-nm emission peak attenuated and emission spectra exhibited weaker double peaks at 612 and 620 nm. This observation suggested that most Eu{sup 3+} ions withdrew from the most emission-active sites, and occupied two distinct chemical sites. With further increasing temperature, the double peaks merged to become broader, indicating that Eu{sup 3+} ions occupied sites more randomly. Emission intensity was the highest at an Eu content of 0.9 at. % and concentration quenching was observed as Eu content was increased. Substitution of Zn{sup 2+} cation sites with Eu{sup 3+} ions was confirmed from the primary X-ray diffraction peaks of ZnO(002); the ZnO lattice expanded as larger numbers of Eu{sup 3+} ions were incorporated. After the films were post-annealed at high temperatures, the diffraction angles approached those of undoped ZnO crystals, which reflected shifting Eu{sup 3+} ions into grain boundaries. The photoabsorption of OH species within a wavelength range of 2700–3000 nm and the Eu{sup 3+} emission intensity revealed correlated behavior. These results confirmed that the presence of OH and/or H species in the film is necessary for emissions from Eu{sup 3+} ions to appear. When OH and/or H species were diminished after high-temperature annealing, Eu{sup 3+} ions existing at substitutional sites became unstable and their emissions were consequently deactivated. The origin of emission-active Eu{sup 3

  3. Steam reformer with catalytic combustor

    DOEpatents

    Voecks, Gerald E.

    1990-03-20

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  4. Steam reformer with catalytic combustor

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  5. Preparation by Candidate Countries for Involvement in the EU Lifelong Learning Policy: Achievements, Gaps and Challenges. Synthesis of the Monographs Exercise. Interim Report.

    ERIC Educational Resources Information Center

    Masson, Jean-Raymond

    The reforms undertaken in the vocational education and training systems and the public employment services systems of European Union (EU) candidate countries in the 10 years since the transition have resulted in the following achievements: (1) participation in upper secondary and tertiary education has increased and curricula for general education…

  6. Questioning the Role of Internationalization in the Nationalization of Higher Education: The Impact of the EU TEMPUS Programme on Higher Education in Syria

    ERIC Educational Resources Information Center

    Ayoubi, Rami M.; Massoud, Hiba K.

    2011-01-01

    Given the need for major reform of the higher education programmes in Syria, and answering the voices that question the role of European Union (EU) in assisting the development of the higher education sector, this study presents an analysis of the contribution of (TEMPUS) Programme in modernising higher education in Syria. The study compares the…

  7. Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent HalidesAB2I5:Eu2+(A=Li–Cs;B=Sr, Ba)

    DOE PAGESBeta

    Fang, C.  M.; Biswas, Koushik

    2015-07-22

    Several rare-earth-doped, heavy-metal halides have recently been identified as potential next-generation luminescent materials with high efficiency at low cost. AB2I5:Eu2+ (A=Li–Cs; B=Sr, Ba) is one such family of halides. Its members, such as CsBa2I5:Eu2+ and KSr2I5:Eu2+, are currently being investigated as high-performance scintillators with improved sensitivity, light yield, and energy resolution less than 3% at 662 keV. Within the AB2I5 family, our first-principles-based calculations reveal two remarkably different trends in Eu site occupation. The substitutional Eu ions occupy both eightfold-coordinated B1(VIII) and the sevenfold-coordinated B2(VII) sites in the Sr-containing compounds. However, in the Ba-containing crystals, Eu ions strongly prefer themore » B2(VII)sites. This random versus preferential distribution of Eu affects their electronic properties. The calculations also suggest that in the Ba-containing compounds one can expect the formation of Eu-rich domains. These results provide atomistic insight into recent experimental observations about the concentration and temperature effects in Eu-doped CsBa2I5. We discuss the implications of our results with respect to luminescent properties and applications. We also hypothesize Sr, Ba-mixed quaternary iodides ABaVIIISrVIII5:Eu as scintillators having enhanced homogeneity and electronic properties.« less

  8. Visible quantum cutting in LiGdF4:Eu3+ through downconversion

    PubMed

    Wegh; Donker; Oskam; Meijerink

    1999-01-29

    For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of two visible photons for each vacuum ultraviolet photon absorbed is demonstrated in Eu3+-doped LiGdF4 with the concept of downconversion. Upon excitation of Gd3+ with a high-energy photon, two visible photons can be emitted by Eu3+ through an efficient two-step energy transfer from Gd3+ to Eu3+, with a quantum efficiency that approaches 200 percent. PMID:9924020

  9. Reforming Welfare in America. Book Review.

    ERIC Educational Resources Information Center

    Jennings, Edward T., Jr.

    1996-01-01

    Reviews three books on welfare reform: "The Poverty of Welfare Reform" (Joel F. Handler); "The Politics of Welfare Reform" (Donald F. Norris, Lyke Thompson, editors); and "Living on the Edge: The Realities of Welfare in America" (Mark Robert Rank). (JOW)

  10. Reforming Reforms: Changing Incentives in Education Finance in Vermont

    ERIC Educational Resources Information Center

    Schmidt, Stephen J.; Scott, Karen

    2006-01-01

    In 1997, Vermont passed Act 60, which reformed its education finance system to achieve greater equality of spending. The reform encouraged wealthy towns to reduce spending; it was politically unpopular and was replaced, in 2004, by Act 68. We analyze the spending incentives created by the two acts and estimate the effects the change will have on…

  11. Reform in the garden.

    PubMed

    Wise, M Norton; Wise, Elaine M

    2002-12-01

    English gardens powered by steam engines offer an intriguing view of how technological and scientific progress was naturalized in the landscape of 19th-century Prussia, and in Prussian culture, during the early years of industrial modernization. One such garden is Peacock Island, in the Havel River near Potsdam. A product of the reform era that preceded and followed the Napoleonic Wars, it expressed the goal of Friedrich Wilhelm III and his government to enter into the British system of factory production and world trade. Modern science, as represented especially by Alexander von Humboldt, played a prominent role. PMID:12535923

  12. Novel Reforming Catalysts

    SciTech Connect

    Pfefferle, Lisa D; Haller, Gary L

    2012-10-16

    Aqueous phase reforming is useful for processing oxygenated hydrocarbons to hydrogen and other more useful products. Current processing is hampered by the fact that oxide based catalysts are not stable under high temperature hydrothermal conditions. Silica in the form of structured MCM-41 is thermally a more stable support for Co and Ni than conventional high surface area amorphous silica but hydrothermal stability is not demonstrated. Carbon nanotube supports, in contrast, are highly stable under hydrothermal reaction conditions. In this project we show that carbon nanotubes are stable high activity/selectivity supports for the conversion of ethylene glycol to hydrogen.

  13. Hydrogen-based power generation from bioethanol steam reforming

    NASA Astrophysics Data System (ADS)

    Tasnadi-Asztalos, Zs.; Cormos, C. C.; Agachi, P. S.

    2015-12-01

    This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO2 emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

  14. Hydrogen-based power generation from bioethanol steam reforming

    SciTech Connect

    Tasnadi-Asztalos, Zs. Cormos, C. C. Agachi, P. S.

    2015-12-23

    This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO{sub 2} emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

  15. Data-driven discovery of energy materials: efficient BaM2Si3O10 : Eu2+ (M = Sc, Lu) phosphors for application in solid state white lighting.

    PubMed

    Brgoch, Jakoah; Hasz, Kathryn; Denault, Kristin A; Borg, Christopher K H; Mikhailovsky, Alexander A; Seshadri, Ram

    2014-01-01

    In developing phosphors for application in solid state lighting, it is advantageous to target structures from databases with highly condensed polyhedral networks that produce rigid host compounds. Rigidity limits channels for non-radiative decay that will decrease the luminescence quantum yield. BaM(2)Si(3)O(10) (M = Sc, Lu) follows this design criterion and is studied here as an efficient Eu(2+)-based phosphor. M = Sc(3+) and Lu(3+) compounds with Eu(2+) substitution were prepared and characterized using synchrotron X-ray powder diffraction and photoluminescence spectroscopy. Substitution with Eu(2+) according to Ba(1-x)Eu(x)Sc(2)Si(3)O(10) and Ba(1-x)Eu(x)Lu(2)Si(3)O(10) results in UV-to-blue and UV-to-blue-green phosphors, respectively. Interestingly, substitution with Eu(2+) in the Lu(3+) containing material produces two emission peaks at low temperature and with 365 nm excitation, as allowed by the two substitution sites. The photoluminescence of the Sc(3+) compound is robust at high temperature, decreasing by only 25% of its room temperature intensity at 503 K, while the Lu-analogue suffers a large drop (75%) from its room temperature intensity. The decrease in emission intensity is explained as stemming from charge transfer quenching due to the short distances separating the luminescent centers on the Lu(3+) substitution site. The correlation between structure and optical response in these two compounds indicates that even though the structures are three-dimensionally connected, high symmetry is required to prevent structural distortions that could impact photoluminescence. PMID:25592992

  16. Mesoporous hybrids containing Eu 3+ complexes covalently bonded to SBA-15 functionalized: Assembly, characterization and photoluminescence

    NASA Astrophysics Data System (ADS)

    Li Kong, Li; Yan, Bing; Li, Ying

    2009-07-01

    A novel series of luminescent mesoporous organic-inorganic hybrid materials has been prepared by linking Eu 3+ complexes to the functionalized ordered mesoporous SBA-15 which was synthesis by a co-condensation process of 1,3-diphenyl-1,3-propanepione (DBM) modified by the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC), tetraethoxysilane (TEOS), Pluronic P123 surfactant as a template. It was demonstrated that the efficient intramolecular energy transfer in the mesoporous material Eu(DBMSi-SBA-15) 3phen mainly occurred between the modified DBM (named as DBM-Si) and the central Eu 3+ ion. So the Eu(DBMSi-SBA-15) 3phen showed characteristic emission of Eu 3+ ion under UV irradiation with higher luminescence quantum efficiency. Moreover, the mesoporous hybrid materials exhibited excellent thermal stability as the lanthanide complex was covalently bonded to the mesoporous matrix.

  17. Enhanced Luminescence of Eu-Doped TiO2Nanodots

    PubMed Central

    2009-01-01

    Monodisperse and spherical Eu-doped TiO2nanodots were prepared on substrate by phase-separation-induced self-assembly. The average diameters of the nanodots can be 50 and 70 nm by changing the preparation condition. The calcined nanodots consist of an amorphous TiO2matrix with Eu3+ions highly dispersed in it. The Eu-doped TiO2nanodots exhibit intense luminescence due to effective energy transfer from amorphous TiO2matrix to Eu3+ions. The luminescence intensity is about 12.5 times of that of Eu-doped TiO2film and the luminescence lifetime can be as long as 960 μs. PMID:20596343

  18. A neutron scintillator based on transparent nanocrystalline CaF2:Eu glass ceramic

    NASA Astrophysics Data System (ADS)

    Struebing, Christian; Chong, JooYun; Lee, Gyuhyon; Zavala, Martin; Erickson, Anna; Ding, Yong; Wang, Cai-Lin; Diawara, Yacouba; Engels, Ralf; Wagner, Brent; Kang, Zhitao

    2016-04-01

    There are no efficient Eu2+ doped glass neutron scintillators reported due to low doping concentrations of Eu2+ and the amorphous nature of the glass matrix. In this work, an efficient CaF2:Eu glass ceramic neutron scintillator was prepared by forming CaF2:Eu nanocrystals in a 6Li-containing glass matrix. Through appropriate thermal treatments, the scintillation light yield of the transparent glass ceramic was increased by a factor of at least 46 compared to the as-cast amorphous glass. This improvement was attributed to more efficient energy transfer from the CaF2 crystals to the Eu2+ emitting centers. Further light yield improvement is expected if the refractive index of the glass matrix can be matched to the CaF2 crystal.

  19. Diffused phase transition of Ba1- x Eu x TiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Jun, Byeong-Eog; Choi, Byung Chun; Jeong, Jung Hyun; Moon, Byung Kee

    2016-06-01

    By applying the sol-gel method, we fabricated Ba1- x Eu x TiO3 (BET) ceramics as a single peroveskite phase in the composition range of x = 0 ~ 0.20. The BET ceramics displayed a ferroelectric phase transition temperature that changed from 120 °C to 80 °C, and exhibited the coexistance of the tetragonal, and cubic structures as the Eu composition was increased. They also displayed anomalous dielectric behaviors related to structural relaxation in the temperature range from 200 °C to 600 °C. We considered the Arrhenius temperature dependence of the dielectric relaxation time by using the electric modulus formalism. The characteristic activation energy was thought to be related with the substitution of Eu (Eu2+, Eu3+) ions for Ba2+ or Ti4+ ions in the perovskite structure.

  20. Radiation damage mechanisms for luminescence in Eu-doped GaN

    SciTech Connect

    Tringe, J. W.; Felter, T. E.; Talley, C. E.; Morse, J. D.; Stevens, C. G.; Castelaz, J. M.; Wetzel, C.

    2007-03-01

    Thin films of Eu-doped GaN were irradiated with 500 keV He{sup +} ions to understand radiation damage mechanisms and to quantify luminescence efficiency. The dependence of ion-beam-induced luminescence intensity on ion fluence was consistent with the simultaneous creation of nonradiative defects and the destruction of luminescent centers associated with 4f-4f core-level transitions in Eu{sup 3+}. This model contrasts with a previous description which takes into account only nonradiative defect generation in GaN:Eu. Based on light from a BaF{sub 2} scintillator standard, the luminescent energy generation efficiency of GaN:Eu films doped to {approx}3x10{sup 18} cm{sup -3} Eu is estimated to be {approx}0.1%.

  1. Electricity reform and sustainable development in China

    NASA Astrophysics Data System (ADS)

    Williams, James H.; Kahrl, Fredrich

    2008-10-01

    Reducing the environmental impact of supplying electricity is a key to China's sustainable development, and a focus of both domestic and international concerns with greenhouse gas emissions. The environmental performance of the electricity sector is strongly affected by its institutional arrangements: regulatory frameworks, wholesale markets, pricing mechanisms, planning and coordination, and enforcement and incentive mechanisms. These arrangements are set to change as electricity reforms inaugurated in 2002, but sidetracked by several years of supply shortages, are being resumed. In this paper we examine the impact of electricity reform on environmental sustainability by analyzing case studies of four environmental initiatives in the electricity sector: retirement of inefficient generators, installation of pollution control equipment, renewable energy development, and efforts to promote energy efficiency. We find that implementation of these policies falls short of objectives for two main underlying reasons: conflicting priorities between central and provincial governments, and ineffective regulation. Sustainability will be best served not by redoubling short-term supply-oriented, market-based reforms, but by better aligning central and provincial government incentives, and by developing competent, independent regulation at the provincial level. China's central government and sub-national governments in industrialized countries can both contribute to the latter goal.

  2. Quantitative analysis of Eu 2+ and Eu 3+ in LiCl-KCl eutectic melt by spectrophotometry and electrochemistry

    NASA Astrophysics Data System (ADS)

    Kim, Tack-Jin; Uehara, Akihiro; Nagai, Takayuki; Fujii, Toshiyuki; Yamana, Hajimu

    2011-02-01

    The redox behavior of Eu 2+ and Eu 3+ in the LiCl-KCl eutectic at 773 K was investigated. Since the equilibrium potential of the melt is very close to the redox potential of the Eu 3+|Eu 2+ couple, the Eu 2+ and Eu 3+ species coexist. Quantitative analysis of Eu 2+ and Eu 3+ was performed by spectrophotometry and by potentiometry. Under the coexistence of Eu 2+ and Eu 3+, potentiometric titration of Eu ion using a yttria-stabilized zirconia membrane electrode (YSZME) was performed by changing the concentration of O 2-. The formation of the europium oxychloride, EuOCl, was confirmed by X-ray diffraction analysis, whiles no precipitation of the oxides, EuO and Eu 2O 3, was found. The equivalent point of the EuOCl formation ( x = [O 2-] added/[Eu] total) was shifted to a smaller value from the theoretical value ( x = 1) due to the coexisting Eu 2+. The contribution of the coexisting Eu 2+ to the formation of EuOCl was estimated by using [Eu 2+]/[Eu 3+] as determined by potentiometry and this was subtracted from the titration data. The solubility product of EuOCl was determined to be p ks(EuOCl) = 7.81 ± 0.10.

  3. Climate policy: Reforming emissions trading

    NASA Astrophysics Data System (ADS)

    Edenhofer, Ottmar

    2014-08-01

    Courageous steps are required to reform the European Union Emissions Trading Scheme. To this end, an independent carbon authority has been proposed -- this is a move in the right direction, but should be part of a much broader discussion about reforming emissions trading.

  4. Contradictions in Chinese Language Reform.

    ERIC Educational Resources Information Center

    Cheng, Chin-Chuan

    The Draft of the Second Chinese Character Simplification Scheme proposed by the Chinese Committee on Language Reform, published in 1977, is discussed. The political history of the draft and current uncertainty about character simplification are examined, and a rigorous methodology for determining the success rate of a script reform is proposed.…

  5. The Other Face of Reform.

    ERIC Educational Resources Information Center

    Ahern, Ursula M.; Compton, Cynthia M.

    2001-01-01

    According to William Spady's "Beyond Counterfeit Reforms," politically driven, mechanistic "reforms" box educators into smaller, limiting ways of thinking and running schools. Donald McAdams's book "Fighting to Save Our Urban Schools...and Winning!" shows the salubrious effects of high expectations and community involvement. (MLH)

  6. Reform in Polish Vocational Education

    ERIC Educational Resources Information Center

    Wojcicka, Maria

    2004-01-01

    The article presents the essential concept of reforms, implemented in Poland's education system since the early 1990s and some of their outcomes. Special attention is paid to one particular aspect of the reforms, i.e. structural diversification of the system, leading to diversification of education levels and corresponding diplomas. The article…

  7. International Handbook of Educational Reform.

    ERIC Educational Resources Information Center

    Cookson, Peter W., Jr., Ed.; And Others

    This book provides an overview of education reform in 27 countries. Following the introduction by Peter W. Cookson, Jr., Alan R. Sadovnik, and Susan F. Semel, part 1 offers national case studies of educational reform in the 1980s. Chapters include: (2) "Argentina" (Ana Munoz-Sandoval); (3) "Australia" (Richard Teese); (4) "Brazil" (Robert Cowen…

  8. Emotional Intelligence and Educational Reform

    ERIC Educational Resources Information Center

    Neophytou, Lefkios

    2013-01-01

    This paper focuses on the notion of educational reform and discusses Emotional Intelligence (EI) in the context of the modernist-postmodernist debate. It is argued that through the application of EI into contemporary societies a new wave of reform emerges that provides science with normative power over the emotional world of individuals. This…

  9. Reforming Teacher Education in Tanzania

    ERIC Educational Resources Information Center

    Hardman, Frank; Abd-Kadir, Jan; Tibuhinda, Audax

    2012-01-01

    It is widely acknowledged that in order to improve the quality of education in primary schools in developing countries there is a need to place pedagogy and its training implications at the centre of teacher education reform. Like many countries in Eastern and Southern Africa, Tanzania has introduced various initiatives and reforms to improve the…

  10. Free Speech and Campaign Reform.

    ERIC Educational Resources Information Center

    Sharp, Harry, Jr.

    The Federal Election Campaign Act of 1971, a political campaign reform measure, was enacted to limit campaign contributions and independent expenditures, to mandate disclosure of contributors, and to establish public financing of campaigns, all to minimize the opportunity for political corruption. Unfortunate implications of such reform on the…

  11. Teachers' Perspectives on Evaluation Reform

    ERIC Educational Resources Information Center

    Donaldson, Morgaen L.

    2012-01-01

    Despite growing momentum to reform teacher evaluation in order to increase its impact on teachers' practice and persistence in the profession, very little research examines how current reforms influence teachers' attitudes or reported instructional practices. Do the new evaluation systems lead to enhancements in teachers' instruction overall? And…

  12. School Reform: Past and Present.

    ERIC Educational Resources Information Center

    Parker, Franklin

    United States educational history is full of uncertain reform attempts beginning with colonial New England's school reform goal of salvation in this world as a preparation for eternal life in the next. A more practical type of education characterized the Early National Period. Monitorial schools and communal schools, as in New Harmony, Indiana,…

  13. Curriculum Reform: Discovering the Void

    ERIC Educational Resources Information Center

    LaDuca, Anthony

    1972-01-01

    Contends that intensive activity and rapid change in curriculum reform is at an end; that areas of urban and vocational education in the reform process have been ignored; and that the level of knowledge in curriculum and instruction has not advanced. Appeals for exploratory research to establish the foundation for constructing a theory of…

  14. Educational Reform and Vocational Education.

    ERIC Educational Resources Information Center

    Milne, Ann M., Ed.

    This document contains six studies that were commissioned for the National Assessment of Vocational Education. "Introduction" (Ann M. Milne) provides an overview of the reforms of the 1980s. "The Impact of Educational Reform on Vocational Education" (Marion Asche, Donald E. Elson, Ann Echols, Arthur Williams) examines primary strategies of reform…

  15. Middle Grades Reform. Literature Review

    ERIC Educational Resources Information Center

    Blazer, Christie

    2008-01-01

    Researchers and policymakers have pointed to the lagging scores of eighth graders on international, national, and state assessments as evidence that students are not prepared to meet high academic standards and that middle grades reform is needed. In response to these concerns, educators have introduced reforms designed to provide middle-level…

  16. George's Complaint: Reforming the Dragon

    ERIC Educational Resources Information Center

    Buxton, Bruce

    2007-01-01

    The evangelical tone and history of American culture has long been identified as a force for anti-intellectualism. The metaphors of educational reform are a demonstration of how this plays out. The very nature of the positivist social science research used to support proposed reform is anti-intellectual and feeds a debate that favors extremes over…

  17. Electronic Structure of EuAl4 Studied by Photoelectron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobata, Masaaki; Fujimori, Shin-ichi; Takeda, Yukiharu; Okane, Tetsuo; Saitoh, Yuji; Kobayashi, Keisuke; Yamagami, Hiroshi; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-09-01

    The electronic structure of the divalent Eu compound EuAl4, which shows a charge density wave transition at TCDW = 140 K, was studied by hard X-ray angle-integrated photoelectron spectroscopy (HAXPES) and soft X-ray angle-resolved photoelectron spectroscopy (ARPES). The valence band and core-level spectra obtained by HAXPES are consistent with the divalent nature of Eu atoms in EuAl4. From the ARPES results, the Fermi surface as well as band structure in the vicinity of the Fermi energy (EF) of EuAl4 are very similar to those of its isostructural divalent Sr compound SrAl4, which has no 4f electrons. This suggests that the Eu atoms are divalent in EuAl4, and the 4f electrons are localized below 1.8 eV with the Eu 4f7 electronic configuration in the ground state. The ARPES spectra measured along the Γ-(Σ)-Z high-symmetry line did not show significant temperature dependences above and below TCDW within the energy resolution of 80-90 meV. Moreover, the Fermi surface mapping along the kz direction showed that both EuAl4 and SrAl4 have mostly three-dimensional electronic structures, suggesting that the nesting of the Fermi surface is not simple. The Fermi surface and the band structure of EuAl4 were well explained by the band-structure calculation of SrAl4 based on the local density approximation.

  18. Pension Reform in China.

    PubMed

    Liu, Tao; Sun, Li

    2016-01-01

    This article analyzes China's pension arrangement and notes that China has recently established a universal non-contributory pension plan covering urban non-employed workers and all rural residents, combined with the pension plan covering urban employees already in place. Further, in the latest reform, China has discontinued the special pension plan for civil servants and integrated this privileged welfare class into the urban old-age pension insurance program. With these steps, China has achieved a degree of universalism and integration of its pension arrangement unprecedented in the non-Western world. Despite this radical pension transformation strategy, we argue that the current Chinese pension arrangement represents a case of "incomplete" universalism. First, its benefit level is low. Moreover, the benefit level varies from region to region. Finally, universalism in rural China has been undermined due to the existence of the "policy bundle." Additionally, we argue that the 2015 pension reform has created a situation in which the stratification of Chinese pension arrangements has been "flattened," even though it remains stratified to some extent. PMID:26549002

  19. Enhanced stability of Eu in GaN nanoparticles: Effects of Si co-doping

    NASA Astrophysics Data System (ADS)

    Kaur, Prabhsharan; Sekhon, S. S.; Zavada, J. M.; Kumar, Vijay

    2015-06-01

    Ab initio calculations on Eu doped (GaN)n (n = 12, 13, and 32) nanoparticles show that Eu doping in nanoparticles is favorable compared with bulk GaN as a large fraction of atoms lie on the surface where strain can be released compared with bulk where often Eu doping is associated with a N vacancy. Co-doping of Si further facilitates Eu doping as strain from an oversized Eu atom and an undersized Si atom is compensated. These results along with low symmetry sites in nanoparticles make them attractive for developing strongly luminescent nanomaterials. The atomic and electronic structures are discussed using generalized gradient approximation (GGA) for the exchange-correlation energy as well as GGA + U formalism. In all cases of Eu (Eu + Si) doping, the magnetic moments are localized on the Eu site with a large value of 6μB (7μB). Our results suggest that co-doping can be a very useful way to achieve rare-earth doping in different hosts for optoelectronic materials.

  20. Low-temperature solvothermal synthesis of EuS hollow microspheres

    SciTech Connect

    Peng, Yong; Wang, Hong; Li, Peng; Fu, Yao Xing, Mingming; Jiang, Tao; Luo, Xixian

    2014-09-15

    Graphical abstract: Synthesis of EuS hollow microspheres at low-temperature via solvothermal method for the first time. - Highlights: • We adopt an improved method to synthesise the (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in deionized water. • We have successfully synthesised the EuS hollow microsphere at 230 °C in acetonitrile. • The price of acetonitrile is more inexpensive, so the price of preparation was reduced. - Abstract: EuS crystals are synthesized by low-temperature solvothermal decomposition of the single source precursor complex (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in acetonitrile. X-ray powder diffraction, scanning electron microscopy, granulocyte diameter statistical analysis, surface energy-dispersive X-ray spectroscopy analysis, and UV–vis absorption spectroscopy are used to characterize the structure and properties of the obtained EuS crystals. The results show that the formed EuS crystals are uniform hollow microspheres with a typical cubic phase structure of rock salt and the average particle size of 2.01 μm. The mechanisms for the thermal decomposition of the precursor complex and the formation of the EuS hollow microspheres are postulated based on the experimental observations and previous reports.

  1. Synthesis, characterization and luminescence properties of Eu3+-doped hydroxyapatite nanocrystal and the thermal treatment effects

    NASA Astrophysics Data System (ADS)

    Silva, Flávia R. O.; de Lima, Nelson B.; Bressiani, Ana Helena A.; Courrol, Lilia C.; Gomes, Laércio

    2015-09-01

    In this work, we present the synthesis, characterization and the luminescence properties of Ca10(PO4)6(OH)2 (hydroxyapatite/HAp) nanocrystals doped with europium trivalent ions. The most important processes that lead to europium emissions in the visible region were identified. Eu:HAp nanopowder excited at 394 nm (or 460 nm) exhibits several emissions: (i) weak emissions at 579 nm, 592 nm and 616 nm due to the 5D0 → 7F0, 5D0 → 7F1 and 5D0 → 7F2 transitions, respectively, with europium ion occupying site I in hydroxyapatite structure and (ii) strong emissions due to the 5D0 → 7F0 (574 nm), 5D0 → 7F1 (602 nm) and 5D0 → 7F2 (610-630 nm) transitions, when Eu3+ is occupying site II. The emission spectrum and the time-resolved luminescence analysis showed that the HAp nanocrystals (nanopowder) thermally treated at temperature (T) between 500 and 800 °C have a change in the initial Eu3+ site distribution of 100 % of Eu3+ at site I to a more stable one where the majority of europium ions are at site II: 30% remains at site I and 70% migrates to site II. In addition, an enhancement of the Eu3+ emission intensity is observed due to the increasing crystallite size. A time-resolved luminescence investigation using a short pulse laser excitation at 460 nm was employed to measure the luminescence decays and to determine the most important mechanisms involved in the deexcitation process of 5D0 excited state of Eu3+, where it is seen a fast (2.9 μs) energy transfer from Eu3+- site I (donor) to Eu3+- site II (acceptor) in the thermally treated nanopowders with T > 500 °C. The initial presence of 100% of Eu3+ at site I in the synthesized nanocrystals is gradually modified by the thermal treatments with temperatures above 500 °C by thermal activation of Ca2+ vacancy (the charge compensator) diffusion through the HAp lattice, which propitiates the Ca2+- vacancies and Eu3+ ions to exchange positions in the lattice. By this thermal activated mechanism, Eu3+ ion migrates

  2. Reforming Practice or Modifying Reforms?: Elementary Teachers' Response to the Tools of Reform

    ERIC Educational Resources Information Center

    Smith, Leigh K.; Southerland, Sherry A.

    2007-01-01

    Understanding the interaction between internally constructed and externally imposed aspects of the teaching context may be the missing link between calls for school reform and teachers' interpretation and implementation of that reform. Although the context of the local school culture has a profound impact on teachers, there are other external…

  3. Crystal growth of Eu:SrI2 single crystals by micro-pulling-down method and the scintillation properties

    NASA Astrophysics Data System (ADS)

    Yokota, Yuui; Nishimoto, Kei; Kurosawa, Shunsuke; Totsuka, Daisuke; Yoshikawa, Akira

    2013-07-01

    Undoped and Eu doped SrI2 (Eu:SrI2) single crystals were grown by the modified micro-pulling-down (μ-PD) method and their scintillation properties were investigated. Undoped and Eu:SrI2 single crystals with Eu 1%, 2%, 3% and 5% concentrations were obtained by the modified μ-PD method with the removable chamber system and their crystals with approximately 2 mm diameter and 2-3 cm length indicated high transparency. Powder X-ray diffraction patterns of grown Eu:SrI2 crystals revealed that the Eu:SrI2 crystals had a single phase of SrI2 structure and similar lattice parameters regardless of Eu concentrations. In the X-ray radioluminescence spectrum of Eu:SrI2 crystal, the emission peak around 430 nm which was due to the 5d-4f transition of Eu2+ ion was observed. Light yields, energy resolutions and decay times of grown Eu:SrI2 crystals irradiated under γ-ray were evaluated.

  4. Luminescence properties of a new green afterglow phosphor NaBaScSi2O7:Eu(2+).

    PubMed

    Li, Gen; Wang, Yuhua; Zeng, Wei; Chen, Wenbo; Han, Shaochun; Guo, Haijie; Wang, Xicheng

    2015-10-28

    A novel green afterglow phosphor NaBaScSi2O7:Eu(2+) was prepared by a solid state reaction under a reductive atmosphere. The NaBaScSi2O7:Eu(2+) phosphor shows two emission bands centered at about 424 (weak) and 502 nm (strong) due to the substitution of Eu(2+) in both Ba(+) and Na(2+) sites, and energy transfer from EuBa (424 nm) to EuNa (502 nm) was found. Both EuBa and EuNa contribute to the afterglow process while EuNa dominates. Na0.99BaScSi2O7:0.01Eu(2+) exhibits green long lasting phosphorescence, whose duration is more than 1 h. The thermoluminescence properties of NaBaScSi2O7:Eu(2+) and the relationship between thermoluminescence and thermal quenching properties were discussed in detail. This work provides a new and efficient candidate for long lasting phosphorescence materials. PMID:26391314

  5. Site and local structure of activator Eu{sup 2+} in phosphor Ca{sub 10−x}(PO{sub 4}){sub 6}Cl{sub 2}:xEu{sup 2+}

    SciTech Connect

    Wang, Chun-Hai; Gui, Dong-Yun; Qin, Rui; Yang, Feng-Li; Jing, Xi-Ping; Tian, Guang-Shan; Zhu, Wenjun

    2013-10-15

    The site and local structure of activator Eu{sup 2+} in phosphor Ca{sub 10−x}(PO{sub 4}){sub 6}Cl{sub 2}:xEu{sup 2+} is investigated by experiment measurements, first-principle calculations and XAFS simulations. From first-principle calculations, the “local” structure [bond length L(M–O)≤R(M{sup 2+})+R(O{sup 2−})] of host shows a significant deformation (expansion) when Ca{sup 2+} is substituted by Eu{sup 2+}, and Eu{sup 2+} should prefer 6h site to 4f site in the host. The d→f emission of Eu{sup 2+} at 4f site should show a longer wavelength than that of Eu{sup 2+} at 6h site. The XAFS measurement and simulations suggest that the Eu{sup 2+} in our Ca{sub 9.9}(PO{sub 4}){sub 6}Cl{sub 2}:0.1Eu{sup 2+} sample mainly locates at 6h site. In the emission spectrum, two emission profiles of Ca{sub 9.9}(PO{sub 4}){sub 6}Cl{sub 2}:0.1Eu{sup 2+} sample are obtained and assigned. The major one (2.71 eV≈456 nm) should be the emission of Eu{sup 2+} at 6h site. The minor one (2.61 eV≈465 nm) should be that of Eu{sup 2+} at 4f site. - Graphical abstract: The d→f emission of Eu{sup 2+} in Ca{sub 9.9}(PO{sub 4}){sub 6}Cl{sub 2}:0.1Eu{sup 2+} can be assigned as: emission profile at 2.71 eV and 2.61 eV are Eu{sup 2+} at 6h and 4f site, respectively. Display Omitted - Highlights: • Eu{sup 2+} in Ca{sub 10−x}(PO{sub 4}){sub 6}Cl{sub 2}:xEu{sup 2+} causes deformation to “local” structure. • Eu{sup 2+} should prefer 6h site to 4f site in the host from energy aspect. • Emission at 2.71 eV and 2.61 eV should be Eu{sup 2+} at 6h and 4f site.

  6. Luminescence properties of rare earth doped metal oxide nanostructures: A case of Eu-ZnO

    NASA Astrophysics Data System (ADS)

    Sahu, D.; Acharya, B. S.; Panda, N. R.

    2016-05-01

    The present study reports the growth and luminescence properties of Eu doped ZnO nanostructures. The experiment has been carried out by synthesizing the materials by simple wet-chemical method. X-ray diffraction (XRD) studies show expansion of ZnO lattice with the incorporation of Eu ions which has been confirmed from the appearance of Eu2O3 as a minor phase in the XRD pattern. The estimation of crystallite size from XRD results matches closely with the results obtained from transmission electron microscopy. Further, these results show the formation of nanosized Eu-ZnO particles of average size around 60 nm stacked on each other. FTIR studies show the presence of both Zn-O and Eu-O modes in the spectra supporting the results obtained from XRD. The interesting results obtained from photoluminescence (PL) measurements show the presence of both band edge emission in UV region and the defect emissions in violet, blue and green region. The appearance of 5D0→7FJ transitions of Eu3+ ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu3+ ions.

  7. Research of the entry of rare earth elements Eu3+ and La3+ into plant cell.

    PubMed

    Gao, Yongsheng; Zeng, Fuli; Yi, An; Ping, Shi; Jing, Lanhua

    2003-03-01

    Whether rare earth elements can enter into plant cells remains controversial. This article discusses the ultracellular structural localization of lanthanum (La(3+)) and europium (Eu(3+)) in the intact plant cells fed by rare earth elements Eu(3+) and La(3+). Eu-TTA fluorescence analysis of the plasmalemma, cytoplast, and mitochondria showed that Eu(3+) fluorescence intensities in such structures significantly increased. Eu(3+) can directly enter or be carried by the artificial ion carrier A23187 into plant cells through the calcium ion (Ca(2+)) channel and then partially resume the synthesis of amaranthin in the Amaranthus caudatus growing in the dark. Locations of rare earth elements La(3+) and Eu(3+) in all kinds of components of cytoplasmatic organelles were determined with transmission electron microscope, scanning electron microscope, and energy-dispersive X-ray microanalysis. The results of energy-dispersive X-ray microanalysis indicated that Eu(3+) and La(3+) can be absorbed into plant cells and bind to the membranes of protoplasm, chloroplast, mitochondrion, cytoplast, and karyon. These results provide experimental evidence that rare earth elements can be absorbed into plant cells, which would be the basis for interpreting physiological and biochemical effects of rare earth elements on plant cells. PMID:12663949

  8. Efficient sensitization of Eu2+/Mn2+ emissions by Ce3+ doping in NaMgPO4 host under UV excitation

    NASA Astrophysics Data System (ADS)

    Zheng, Zhang; Wanjun, Tang

    2016-03-01

    A series of Ce3+/Eu2+/Mn2+-tridoped NaMgPO4 phosphors were synthesized using the combustion-assisted synthesis method. The luminescence properties and energy transfer from Ce3+/Eu2+ to Mn2+ in NaMgPO4 host have been studied. Co-doping Ce3+/Mn2+ is proved to be an ineffective approach to enhance the red emission of Mn2+, while effective energy transfer from Eu2+ to Mn2+ occurs in NaMgPO4:Eu2+,Mn2+ due to good spectrum overlap between the emission band of NaMgPO4:Eu2+ and the excitation band of NaMgPO4:Eu2+,Mn2+. NaMgPO4:Eu2+,Mn2+ phosphor shows a blue emission centered at 442 and a red emission peaking at 635 nm, which could be ascribed to the allowed 5 d-4 f transition of Eu2+ ions and the 4T1(4G)-6A1(6S) transition of Mn2+ ions, respectively. Co-doping Ce3+ ions can greatly enhance both the emission intensities of Eu2+ and Mn2+ ions, which is attributed to an efficient Ce3+ → Eu2+ → Mn2+ energy transfer and an increase in the number of luminescent centers (Eu2+) on Ce doping.

  9. LaVo4: Eu Phosphor Films with Enhanced Eu Solubility

    SciTech Connect

    Hwang, Harold

    2011-08-11

    Eu doped rare-earth orthovanadates are known to be good red phosphor materials. In particular, LaVO{sub 4}:Eu is a promising candidate due to the low Eu-site point symmetry, and thus high dipole transition probability within Judd-Ofelt theory. However, the low solubility limit (< 3 mol %) of Eu in LaVO{sub 4} prevents its efficient use as a phosphor. We present optical evidence of enhanced Eu solubility as high as 10 mol % in LaVO{sub 4}:Eu thin films grown by pulsed laser deposition and postannealing. The photoluminescent intensity exceeded that of YVO{sub 4}:Eu thin films when excited below the host bandgap, indicating stronger direct emission of Eu in LaVO{sub 4}.

  10. Successfully reforming orthopaedic outpatients.

    PubMed

    Schoch, Peter A; Adair, Lisa

    2012-05-01

    Since 2005, Barwon Health has successfully reformed its orthopaedic outpatient service to address the following issues: increasing number of referrals, inefficient referral management and triage, long waiting times for non-urgent appointments, high 'Did Not Attend' (DNA) rates and poor utilisation of conservative therapies before referral to surgeon. Numerous strategies have been implemented including: waiting list audits, triage guidelines, physiotherapy-led clinics, a DNA policy, an orthopaedic lead nurse role and a patient-focussed booking system. There has been a 66% reduction in the number of patients waiting for their first appointment; an 87% reduction in the waiting time from referral to first appointment; a 10% reduction in new patient DNAs; and more efficient referral management and communication processes. Patients are now seen in clinically appropriate time frames and offered earlier access to a wider range of conservative treatments. PMID:22624648

  11. Road to reform

    SciTech Connect

    South, D.

    1997-04-01

    The power sector is actively exploring and pursuing the myriad opportunities that exist under the concessions and independent power plant laws recently enacted by the Brazilian legislature. While Brazil has not yet finalized the necessary implementing regulations, it has taken positive steps to reform its infrastructure, develop proactive fiscal policies and address the problem of inflation. The author goes on to discuss issues unique to the situation of Brazil as they relate to the ability of foreign companies to break into the business sector, in particular the power generation field. Many rules are in the process of change, but there still remains uncertainties which cloud the question as to the economic viability of investments in the power generation field.

  12. Liquid fuel reformer development.

    SciTech Connect

    Ahmed, S.; Krumpelt, M.; Pereira, C.; Wilkenhoener, R.

    1999-07-30

    At Argonne National Laboratory we are developing a process to convert hydrocarbon fuels to a clean hydrogen feed for a fuel cell. The process incorporates a partial oxidation/steam reforming catalyst that can process hydrocarbon feeds at lower temperatures than existing commercial catalysts. We have tested the catalyst with three diesel-type fuels: hexadecane, low-sulfur diesel fuel, and a regular diesel fuel. We achieved complete conversion of the feed to products. Hexadecane yielded products containing 60% hydrogen on a dry, nitrogen-free basis at 800 C. For the two diesel fuels, higher temperatures, >850 C, were required to approach similar levels of hydrogen in the product stream. At 800 C, hydrogen yield of the low sulfur diesel was 32%, while that of the regular diesel was 52%. Residual products in both cases included CO, CO{sub 2}, ethane, ethylene, and methane.

  13. Luminescence of Eu3+ incorporated into PZT tetragonal ceramics prepared by sol gel

    NASA Astrophysics Data System (ADS)

    González, Federico; Schabes-Retchkiman, Pablo; García-Macedo, Jorge

    2004-09-01

    Luminescence of Eu3+ in Pb(ZrxTi1-x)O3 (PZT) polycrystalline tetragonal samples synthesized by sol-gel processing is reported. Studies by x-ray diffraction, energy dispersive spectroscopy and high resolution transmission electron microscopy demonstrate the incorporation of the dopant in the host. A broad charge transfer band centred around 266 nm was observed in the Eu3+ excitation spectra. Eu3+ is in a low symmetry site. Luminescence was lost between 673 and 1173 K. It was recovered after 1 h of heat treatment at 1273 K, when nanocrystallites were formed.

  14. Monodisperse spherical mesoporous Eu-doped TiO2 phosphor particles and the luminescence properties

    NASA Astrophysics Data System (ADS)

    Yin, Jianbo; Xiang, Liqin; Zhao, Xiaopeng

    2007-03-01

    Monodisperse spherical and mesoporous Eu-doped TiO2 phosphor particles were prepared by nonionic surfactant-assisted soft-chemistry method. It is shown that the phosphor particles possess submicron diameter of about 250nm and narrow size distribution. Under ultraviolet irradiation the particles show characteristic luminescence corresponding to D05-Fj7 of Eu3+. Especially, the calcined particles consisted of mesopores and semicrystalline framework shows the strongest photoluminescence compared to the amorphous particles without annealing and the completely crystalline particles annealed at higher temperature. This is attributed to the energy transfer from titania nanocrystallite to Eu3+ ions dispersed in glassy amorphous titania region.

  15. EuCo2P2 : A model molecular-field helical Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Sangeetha, N. S.; Cuervo-Reyes, Eduardo; Pandey, Abhishek; Johnston, D. C.

    2016-07-01

    The metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below TN=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the a b plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ , high-field magnetization, and magnetic heat capacity of EuCo2P2 single crystals at temperature T ≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ˜T3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and BaCo2P2 , respectively. These values are enhanced by a factor of ˜2.5 above those found from DFT electronic structure calculations for the two compounds. The calculations also find ferromagnetic Eu-Eu exchange interactions within the a b plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χa b(T ≤TN) .

  16. Introducing competition principles into health care through EU law and policy: a case study of the Netherlands.

    PubMed

    van de Gronden, Johan; Szyszczak, Erika

    2014-01-01

    A national health care service is one of the central pillars of the welfare state in Europe. Recent moves to modernise health care, alongside introducing efficiencies through competition have resulted in experimentation and a re-organisation of national health care systems. The experimental nature of the reforms has brought health care into the focus, but uncertain territory, of EU economic law, especially competition law. Added to these pressures, the new EU fiscal measures oblige Member States to avoid excessive budgets and macro-economic imbalances. One constraint on an EU-based system of competition in health care is the effect of decentralisation, resulting in variations at the national level. Thus a case study is taken of the experience in The Netherlands. From this case study, we argue that a new form of Euro-national competition law is emerging for the health care sector with national authorities taking the lead in shaping the contours of this law. PMID:24841529

  17. Structural, photoluminescent and photocatalytic properties of TiO2:Eu3+ coatings formed by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Radić, Nenad; Grbić, Boško; Maletić, Slavica; Stefanov, Plamen; Pačevski, Aleksandar; Vasilić, Rastko

    2016-05-01

    In this paper, we used plasma electrolytic oxidation (PEO) of titanium in water solution containing 10 g/L Na3PO4·12H2O + 2 g/L Eu2O3 powder for preparation of TiO2:Eu3+ coatings. The surfaces of obtained coatings exhibit a typical PEO porous structure. The energy dispersive X-ray spectroscopy analysis showed that the coatings are mainly composed of Ti, O, P, and Eu; it is observed that Eu content in the coatings increases with PEO time. The X-ray diffraction analysis indicated that the coatings are crystallized and composed of anatase and rutile TiO2 phases, with anatase being the dominant one. X-ray photoelectron spectroscopy revealed that Ti 2p spin-orbit components of TiO2:Eu3+ coatings are shifted towards higher binding energy, with respect to pure TiO2 coatings, suggesting that Eu3+ ions are incorporated into TiO2 lattice. Diffuse reflectance spectroscopy showed that TiO2:Eu3+ coatings exhibit evident red shift with respect to the pure TiO2 coatings. Photoluminescence (PL) emission spectra of TiO2:Eu3+ coatings are characterized by sharp emission bands in orange-red region ascribed to f-f transitions of Eu3+ ions from excited level 5D0 to lower levels 7FJ (J = 0, 1, 2, 3, and 4). The excitation PL spectra of TiO2:Eu3+ coatings can be divided into two regions: the broad band region from 250 nm to 350 nm associated with charge transfer state of Eu3+ and the series of sharp peaks in the range from 350 nm to 550 nm corresponding to direct excitation of the Eu3+ ions. It is observed that the intensity of peaks in excitation and emission PL spectra increases with the concentration of Eu3+, but the peak positions remain practically unchanged. The ratio of PL emission for electric and magnetic dipole transitions indicates highly asymmetric environment around Eu3+ ions. The photocatalytic activity (PA) of TiO2:Eu3+ coatings is evaluated by measuring the photodegradation of methyl orange under simulated sunlight conditions. It is shown that PEO time, i.e., the amount

  18. Reforming and Restructuring Education. UCEA Monograph Series.

    ERIC Educational Resources Information Center

    Wendel, Frederick C., Ed.

    This booklet contains four selected conference papers on educational reform and restructuring. In "Can Rational Organization Models Really Reform Anything? A Case Study of Reform in Chicago," Fenwick English describes reform efforts in the Chicago Public Schools and examines the political, social, organizational, and bureaucratic factors that have…

  19. Reforming Our Expectations about Juvenile Justice

    ERIC Educational Resources Information Center

    Rodriguez, Pamela F.; Baille, Daphne M.

    2010-01-01

    Typing the term "juvenile justice reform" into a Google[TM] search will result in 60 pages of entries. But what is meant by juvenile justice reform? What does it look like? How will one know when it is achieved? This article defines juvenile justice reform, discusses the principles of effective reform, and describes the practice of juvenile…

  20. Pastors and the "Perpetuum Mobile": The Dynamics of Professional Learning in Times of Reform

    ERIC Educational Resources Information Center

    Reite, Ingrid Chr.

    2015-01-01

    In a changing knowledge society, many workplaces experience a great number of reforms, implying improvement, new ways of working and professional learning. When a reform is introduced, however, does a professional act as an ever-moving machine--a "perpetuum mobile"--always learning with full energy? In this article, I ask the following:…

  1. Tuning Mixed-Valent Eu(2+) /Eu(3+) in Strontium Formate Frameworks for Multichannel Photoluminescence.

    PubMed

    Liu, Wei; Liu, Lijia; Wang, Yanlong; Chen, Lanhua; McLeod, John A; Yang, Linju; Zhao, Jia; Liu, Zhiyong; Diwu, Juan; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Liu, Guokui; Wang, Shuao

    2016-08-01

    Cooperative performance of mixed-valent Eu(2+) /Eu(3+) in single-compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu(2+) oxidation. Using the tunable nature of the metal-ion nodes in metal-organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu(2+) /Eu(3+) with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic- and sensitized-emissions of Eu(2+) and Eu(3+) , and long-lived luminescence from charge transfer. Color rendering can be easily achieved by fine-tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu(2+) /Eu(3+) emissions provides outstanding properties for applications as self-calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb(3+) into the MOFs results in white light, utilizing all Eu(2+) ,Tb(3+) , and Eu(3+) emissions in a single crystalline lattice. PMID:27305606

  2. Perspective: The road to reform

    SciTech Connect

    Howe, J.B. )

    1994-04-01

    The rapid transformation underway in the utility industry provides ample evidence that the reality of the Energy Policy Act of 1992 is sinking in. This law reflected Congress's conclusion that competition in wholesale power generation-at the plant busbar-is a demonstrable reality. It expressed the vision of a fully competitive wholesale generation market, with suppliers linked to markets through a grid that would provide service on a nondiscriminatory basis. But will consumers reap the full benefits of effective competition at the wholesale generation level Or will more disorderly forms of competition emerge, reflecting a hybrid of deregulation and old-fashioned monopoly tactics Along the latter course we run the risk of cost shifts among customer classes, customer defections, diminished utility cooperation, and higher overall costs to society. In short, the vision of a competitive market in wholesale generation will not come about without thoughtful efforts at defining the relevant market, as well as careful attention to the management of a difficult transition away from outmodes mindsets and regulatory models. As a national trade association representing independent power producers (IPPs) and suppliers of goods and services to the competitive wholesale electric generation industry, the Electric Generation Association (EGA) believes that constructive dialogue will yield the best approach to managing this difficult process of transition. In that spirit, the EGA Emerging Operational Issues Committee recently released a while paper, [open quotes]Electrifying Change: Strategies for Structural Reform in the Electric Industry,[close quotes] which forms the basis for this article.

  3. A reforming accountability: GPs and health reform in New Zealand.

    PubMed

    Jacobs, K

    1997-01-01

    Over the last ten years or so, many countries have undertaken public sector reforms. As a result of these changes, accounting has come to play a more important role. However, many of the studies have only discussed the reforms at a conceptual level and have failed to study how the reforms have been implemented and operated in practice. Based on the work of Lipsky (1980) and Gorz (1989), it can be argued that those affected by the reforms have a strong incentive to subvert the reforms. This prediction is explored via a case study of general practitioner (GP) response to the New Zealand health reforms. The creation of Independent Practice Associations (IPAs) allowed the State to impose contractual-accountability and to cap their budget exposure for subsidies. From the GP's perspective, the IPAs absorbed the changes initiated by the State, and managed the contracting, accounting and budgetary administration responsibilities that were created. This allowed individual GPs to continue practising as before and provided some collective protection against the threat of state intrusion into GP autonomy. The creation of IPAs also provided a new way to manage the professional/financial tension, the contradiction between the professional motivation noted by Gorz (1989) and the need to earn a living. PMID:10175302

  4. Magnetic and Fermi Surface Properties of EuGa4

    NASA Astrophysics Data System (ADS)

    Nakamura, Ai; Hiranaka, Yuichi; Hedo, Masato; Nakama, Takao; Miura, Yasunao; Tsutsumi, Hiroki; Mori, Akinobu; Ishida, Kazuhiro; Mitamura, Katsuya; Hirose, Yusuke; Sugiyama, Kiyohiro; Honda, Fuminori; Settai, Rikio; Takeuchi, Tetsuya; Hagiwara, Masayuki; Matsuda, Tatsuma D.; Yamamoto, Etsuji; Haga, Yoshinori; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Harima, Hisatomo; Ōnuki, Yoshichika

    2013-10-01

    We grew a high-quality single crystal EuGa4 with the tetragonal structure by the Ga self-flux method, and measured the electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermoelectric power and de Haas--van Alphen (dHvA) effect, together with the electrical resistivity and thermoelectric power under pressure. EuGa4 is found to be a Eu-divalent compound without anisotropy of the magnetic susceptibility in the paramagnetic state and to reveal the same magnetization curve between H \\parallel [100] and [001] in the antiferromagnetic state, where the antiferromagnetic easy-axis is oriented along the [100] direction below a Néel temperature TN=16.5 K. The magnetization curve is discussed on the basis of a simple two-sublattice model. The Fermi surface in the paramagnetic state was clarified from the results of a dHvA experiment for EuGa4 and an energy band calculation for a non-4f reference compound SrGa4, which consists of a small ellipsoidal hole--Fermi surface and a compensated cube-like electron--Fermi surface with vacant space in center. We observed an anomaly in the temperature dependence of the electrical resistivity and thermoelectric power at TCDW=150 K under 2 GPa. This might correspond to an emergence of the charge density wave (CDW). The similar phenomenon was also observed in EuAl4 at ambient pressure. We discussed the CDW phenomenon on the basis of the present peculiar Fermi surfaces.

  5. Polyol-mediated C-dot formation showing efficient Tb3+/Eu3+ emission.

    PubMed

    Dong, Hailong; Kuzmanoski, Ana; Gössl, Dorothee M; Popescu, Radian; Gerthsen, Dagmar; Feldmann, Claus

    2014-07-18

    C-dots (3-5 nm in diameter) obtained by most simple heating of polyols (glycerol, diethylene glycol and PEG 400) show intense blue and green emission (50% quantum yield). Upon modification with TbCl3/EuCl3, energy transfer from the C-dots to the rare-earth metal results in line-type Tb(3+) (green)/Eu(3+) (red) emission with quantum yields up to 85%. PMID:24887063

  6. What Next in School Reform?

    ERIC Educational Resources Information Center

    Barker, Bernard

    2009-01-01

    This article reviews the current state of education reform in the United Kingdom and uses the BBC film "The Choir to explore alternative ways of improving the quality of learning and teaching in schools.

  7. Misrecognition and science education reform

    NASA Astrophysics Data System (ADS)

    Brandt, Carol B.

    2012-09-01

    In this forum, I expand upon Teo and Osborne's discussion of teacher agency and curriculum reform. I take up and build upon their analysis to further examine one teacher's frustration in enacting an inquiry-based curriculum and his resulting accommodation of an AP curriculum. In this way I introduce the concept of misrecognition (Bourdieu and Passeron 1977) to open up new ways of thinking about science inquiry and school reform.

  8. Campaign 2008: healthcare reform revisited.

    PubMed

    Wilensky, Gail R

    2008-10-01

    *An important lesson to be learned from the failed efforts at healthcare reform of the early 1990s is that successful reform cannot be an all-or-nothing proposition. *The McCain and Obama healthcare plans have some elements in common, but they also have important differences. *Whoever wins the election will face the challenge of persuading Congress to go along with his proposal. PMID:18839667

  9. Residency Work-Hours Reform

    PubMed Central

    Nuckols, Teryl K; Escarce, José J

    2005-01-01

    Background In response to proposed federal legislation, the Accreditation Council for Graduate Medical Education limited resident work-hours in July 2003. The cost may be substantial but, if successful, the reform might lower preventable adverse event costs in hospital and after discharge. Objectives This study sought to estimate the reform's net cost in 2001 dollars, and to determine the reduction in preventable adverse events needed to make reform cost neutral from teaching hospital and societal perspectives. Design Cost analysis using published literature and data. Net costs were determined for 4 reform strategies and over a range of potential effects on preventable adverse events. Results Nationwide, transferring excess work to task-tailored substitutes (the lowest-level providers appropriate for noneducational tasks) would cost $673 million; mid-level providers would cost $1.1 billion. Reform strategies promoting adverse events would increase net teaching hospital and societal costs as well as mortality. If task-tailored substitutes decrease events by 5.1% or mid-level providers decrease them by 8.5%, reform would be cost neutral for society. Events must fall by 18.5% and 30.9%, respectively, to be cost neutral for teaching hospitals. Conclusions Because most preventable adverse event costs occur after discharge, a modest decline (5.1% to 8.5%) in them might make residency work-hours reform cost neutral for society but only a much larger drop (18.5% to 30.9%) would make it cost neutral for teaching hospitals, unless additional funds are allocated. Future research should evaluate which reform approaches prevent adverse events and at what cost. PMID:16191130

  10. Public service or commodity goods? Electricity reforms, access, and the politics of development in Tanzania

    NASA Astrophysics Data System (ADS)

    Ghanadan, Rebecca Hansing

    Since the 1990s, power sector reforms have become paramount in energy policy, catalyzing a debate in Africa about market-based service provision and the effects of reforms on access. My research seeks to move beyond the conceptual divide by grounding attention not in abstract 'market forces' but rather in how development institutions shape energy services and actually practice policy on the ground. Using the case of Tanzania, a country known for having instituted some of the most extensive reforms and a 'success story' in Africa, I find that reforms are creating large burdens and barriers for access and use of services, including: increasing costs, enforcement pressures, and measures to impose 'market' discipline. However, I also find that many of the most significant outcomes are not found in direct 'market' changes, but rather how reforms are selective, partial, and shaped by the wider needs and claims of the institutions driving reforms, so that questions of how reforms are implemented, how they are measured, and who tells the story become as important as the policies themselves. Using a multiple-arenas framework, including (i) a household and community level study of urban energy conditions, (ii) a study of service and management conditions at the national electric utility, (iii) an examination of the international policy process, and (iv) a study of the history of electricity services across colonial, post-independence, and reform periods, I show that African energy reforms are a technical and political project connecting energy to international investments, donor aid programs, and elite interests within national governments. Energy reforms also involve fundamental service changes that are reorganizing how the costs and benefits of energy systems are distributed, allocated, and managed. The effects of reform extend beyond formal services to have wide-reaching repercussions within natural resources, and uneven social dynamics on the ground. These features point

  11. The core to regulatory reform

    SciTech Connect

    Partridge, J.W. Jr.

    1993-06-15

    Federal Energy Regulatory Commission (FERC) Orders 436, 500, and 636, the Clean Air Act Amendments of 1990, Public Utility Holding Company Act reform, and the 1992 Energy Policy Act all can have significant effects on an LDC's operations. Such changes in an LDC's environments must be balanced by changes within the utility, its marketplace, and its state regulatory environment. The question is where to start. For Columbia Gas Distribution Cos., based in Columbus, OH, the new operating foundation begins with each employee. Internal strength is critical in designing initiatives that meet the needs of the marketplace and are well-received by regulators. Employees must understand not only the regulatory environment in which the LDC operates, but also how their work contributes to a positive regulatory relationship. To achieve this, Columbia initiated the COntinuing Regulatory Education program, or CORE, in 1991. CORE is a regulatory-focused, information-initiative program coordinated by Columbia's Regulatory Policy, Planning, and Government Affairs Department. The CORE programs can take many forms, such as emerging issue discussions, dialogues with regulators and key parties, updates on regulatory fillings, regulatory policy meetings, and formal training classes. The speakers and discussion facilitators can range from human resource department trainers to senior officers, from regulatory department staff members to external experts, or from state commissioners to executives from other LDCs. The goals of CORE initiatives are to: Support a professional level of regulatory expertise through employee participation in well-developed regulatory programs presented by credible experts. Encourage a constructive state regulatory environment founded on communication and cooperation. CORE achieves these goals via five program levels: introductory basics, advanced learning, professional expertise, crossfunctional dialogues, and external idea exchanges.

  12. Synthesis and optical properties of Eu3+ doped ZnO nanoparticles used for white light emitting diodes.

    PubMed

    Huang, Jinzhao; Liu, Shiyou; Gao, Baojun; Jiang, Tao; Zhao, Yongdan; Liu, Song; Kuang, Lei; Xu, Xijin

    2014-04-01

    ZnO nanoparticles doped with trivalent europium ions (Eu3+) were synthesized by the hydrothermal method. The structural properties of the samples were investigated by the X-ray diffraction (XRD). The results indicated that Eu3+ was incorporated into the lattice of ZnO. Photoluminescence (PL) measurements of ZnO:Eu3+ showed a strong red luminescence emission. Specially, the red emission can be obtained even under the nonresonant excitation of 320 nm, and it is explained by an energy transfer mechanism in which the energy is transferred from ZnO matrix to Eu3+. These results indicate that the ZnO:Eu3+ is the attractive candidate phosphor for the application in phosphor-converted light-emitting diodes (pc-LEDs) as red phosphor. The intensity of Eu3+ PL decreased with the increasing Eu3+ concentration and the concentration quenching mechanism was presented based on non-radiative recombination processes in ZnO and the energy back-transfer from the excited state of Eu3+ to the ZnO host. Moreover, the samples were synthesized under low temperature condition. PMID:24734733

  13. Enhanced stability of Eu in GaN nanoparticles: Effects of Si co-doping

    SciTech Connect

    Kaur, Prabhsharan; Sekhon, S. S.; Zavada, J. M.; Kumar, Vijay

    2015-06-14

    Ab initio calculations on Eu doped (GaN){sub n} (n = 12, 13, and 32) nanoparticles show that Eu doping in nanoparticles is favorable compared with bulk GaN as a large fraction of atoms lie on the surface where strain can be released compared with bulk where often Eu doping is associated with a N vacancy. Co-doping of Si further facilitates Eu doping as strain from an oversized Eu atom and an undersized Si atom is compensated. These results along with low symmetry sites in nanoparticles make them attractive for developing strongly luminescent nanomaterials. The atomic and electronic structures are discussed using generalized gradient approximation (GGA) for the exchange-correlation energy as well as GGA + U formalism. In all cases of Eu (Eu + Si) doping, the magnetic moments are localized on the Eu site with a large value of 6μ{sub B} (7μ{sub B}). Our results suggest that co-doping can be a very useful way to achieve rare-earth doping in different hosts for optoelectronic materials.

  14. Energetics and electronic structure of GaN codoped with Eu and Si

    NASA Astrophysics Data System (ADS)

    Bruno Cruz, A. Vallan; Shinde, Prashant P.; Kumar, Vijay; Zavada, John M.

    2012-01-01

    First principles calculations using pseudopotentials and generalized gradient approximation (GGA) for the exchange-correlation energy show that addition of Si makes Eu doping in GaN energetically favorable. It breaks local symmetry around Eu ions and leads to shallow states below the conduction band that could facilitate intra-4f shell transitions. Silicon atoms on Ga sites act as intrinsic donors transforming Eu from a 3+ to a 2+ state. The half-filled 4f states with a 7 μB magnetic moment on each Eu ion lie within the band gap of GaN and are narrower compared with the only-Eu doping case due to reduced hybridization with the host states. There is a tendency for clustering of Eu ions with ferromagnetic coupling and the ˜5-Å interatomic distance, but EuN phase formation is unfavorable. Further effects of the inclusion of onsite Coulomb interaction U within GGA+U formalism on the electronic structure are discussed.

  15. Regulation reform slows down

    SciTech Connect

    1995-03-29

    Regulatory reformers in Congress are easing off the accelerator as they recognize that some of their more far-reaching proposals lack sufficient support to win passage. Last week the proposed one-year moratorium on new regulations was set back in the Senate by it main sponsor, Sen. Non Nickles (R., OK), who now seeks to replace it with a more moderate bill. Nickel`s substitute bill would give Congress 45 days after a regulation is issued to decide whether to reject it. It also retroactively allows for review of 80 regulations issued since last November 9, 1994. Asked how his new proposal is superior to a moratorium, which is sharply opposed by the Clinton Administration, Nickles says he thinks it is better because its permanent. The Chemical Manufacturer`s Association (CMA) has not publicly made a regulatory moratorium a top priority, but has quietly supported it by joining with other industry groups lobbying on the issue. A moratorium would halt EPA expansion of the Toxics Release Inventory (TRI) and alloys the delisting of several TRI chemicals.

  16. Investigation on the red shift of charge transfer excitation spectra for nano-sized Y 2O 3:Eu 3+

    NASA Astrophysics Data System (ADS)

    Shang, Chunyu; Shang, Xiaohong; Qu, Yuqiu; Li, Meicheng

    2011-01-01

    Based upon the local structure data, the differences of energy bands between bulk and nano-sized Y2O3:Eu3+ have been presented. The volume expansion in nano-sized Y2O3:Eu3+ leads to the shrinkage of band gap and decrease of zero-phonon charge transfer (CT) energy; the enlargement of local disorder in nano-sized Y2O3:Eu3+ leads to the formation of impurity bands and further decrease of zero-phonon CT energy. On the basis of the differences in energy bands, the mechanisms for the decrease of CT energy, i.e., red shift of CT excitation spectra for nano-sized Y2O3:Eu3+ have been clarified.

  17. Let's make a deal: trading malpractice reform for health reform.

    PubMed

    Sage, William M; Hyman, David A

    2014-01-01

    Physician leadership is required to improve the efficiency and reliability of the US health care system, but many physicians remain lukewarm about the changes needed to attain these goals. Malpractice liability-a sore spot for decades-may exacerbate physician resistance. The politics of malpractice have become so lawyer-centric that recognizing the availability of broader gains from trade in tort reform is an important insight for health policy makers. To obtain relief from malpractice liability, physicians may be willing to accept other policy changes that more directly improve access to care and reduce costs. For example, the American Medical Association might broker an agreement between health reform proponents and physicians to enact federal legislation that limits malpractice liability and simultaneously restructures fee-for-service payment, heightens transparency regarding the quality and cost of health care services, and expands practice privileges for other health professionals. There are also reasons to believe that tort reform can make ongoing health care delivery reforms work better, in addition to buttressing health reform efforts that might otherwise fail politically. PMID:24395935

  18. EuCo2P2: A model molecular-field helical Heisenberg antiferromagnet

    DOE PAGESBeta

    Sangeetha, N. S.; Cuervo-Reyes, Eduardo; Pandey, Abhishek; Johnston, D. C.

    2016-07-19

    Here, the metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below TN=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ, high-field magnetization, and magnetic heat capacity of EuCo2P2 single crystals at temperaturemore » T ≤ TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~T3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and BaCo2P2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. The calculations also find ferromagnetic Eu–Eu exchange interactions within the ab plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χab(T ≤ TN).« less

  19. 77 FR 69754 - Promoting Transmission Investment Through Pricing Reform

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... Pricing Reform, Order No. 679, 71 FR 43294 (Jul. 31, 2006), FERC Stats. & Regs. ] 31,222 (2006), order on reh'g, Order No. 679-A, 72 FR 1152 (Jan. 10, 2007), FERC Stats. & Regs. ] 31,236, order on reh'g, 119... Energy Regulatory Commission 18 CFR Parts 2 and 35 Promoting Transmission Investment Through...

  20. Target Allocation Methodology for China's Provinces: Energy Intensity in the 12th FIve-Year Plan

    SciTech Connect

    Ohshita, Stephanie; Price, Lynn

    2011-03-21

    Experience with China's 20% energy intensity improvement target during the 11th Five-Year Plan (FYP) (2006-2010) has shown the challenges of rapidly setting targets and implementing measures to meet them. For the 12th FYP (2011-2015), there is an urgent need for a more scientific methodology to allocate targets among the provinces and to track physical and economic indicators of energy and carbon saving progress. This report provides a sectoral methodology for allocating a national energy intensity target - expressed as percent change in energy per unit gross domestic product (GDP) - among China's provinces in the 12th FYP. Drawing on international experience - especially the European Union (EU) Triptych approach for allocating Kyoto carbon targets among EU member states - the methodology here makes important modifications to the EU approach to address an energy intensity rather than a CO{sub 2} emissions target, and for the wider variation in provincial energy and economic structure in China. The methodology combines top-down national target projections and bottom-up provincial and sectoral projections of energy and GDP to determine target allocation of energy intensity targets. Total primary energy consumption is separated into three end-use sectors - industrial, residential, and other energy. Sectoral indicators are used to differentiate the potential for energy saving among the provinces. This sectoral methodology is utilized to allocate provincial-level targets for a national target of 20% energy intensity improvement during the 12th FYP; the official target is determined by the National Development and Reform Commission. Energy and GDP projections used in the allocations were compared with other models, and several allocation scenarios were run to test sensitivity. The resulting allocations for the 12th FYP offer insight on past performance and offer somewhat different distributions of provincial targets compared to the 11th FYP. Recommendations for reporting

  1. Catalytic reforming of liquid fuels: Deactivation of catalysts

    SciTech Connect

    Spivey, J.J.; Haynes, D.J.; Berry, D.A.; Shekhawat, Dushyant; Gardner, T.H.

    2007-10-01

    The catalytic reforming of logistic fuels (e.g., diesel) to provide hydrogen-rich gas for various fuel cells is inevitably accompanied by deactivation. This deactivation can be caused by various mechanisms, such as carbon deposition, sintering, and sulfur poisoning. In general, these mechanisms are, not independent—e.g., carbon deposition may affect sulfur poisoning. However, they are typically studied in separate experiments, with relatively little work reported on their interaction at conditions typical of liquid fuel reforming. Recent work at the U.S. Dept. of Energy/NETL and Louisiana State University has shown progress in understanding the interaction of these deactivation processes, and catalysts designed to minimize them.

  2. Fabrication and characterization of cubic SrI2(Eu) scintillators for use in array detectors

    NASA Astrophysics Data System (ADS)

    Shimazoe, K.; Koyama, A.; Takahashi, H.; Sakuragi, S.; Yamasaki, Y.

    2016-02-01

    Strontium iodide (SrI2(Eu)) is a promising spectroscopic detector for use in both nuclear security and medical imaging owing to its excellent energy resolution and low internal background radiation. A cubic form is preferable when coupling with a silicon-based photosensor in order to build an array detector for use in applications such as Compton cameras. Here, cubic SrI2(Eu) crystals with 10 mm sides were fabricated and evaluated. The cubic SrI2(Eu) samples coupled to an avalanche photodiode exhibited an energy resolution of approximately 3.6% at 662 keV when using a shaping time of 3 μs. An increase in light output and an improvement of energy resolution were also observed at lower temperatures. The excellent energy resolution of these devices indicates that these crystals are promising potential detectors for use in Compton cameras and other imaging detectors.

  3. Study of Eu{sup 3+} → Eu{sup 2+} reduction in BaAl{sub 2}O{sub 4}:Eu prepared in different gas atmospheres

    SciTech Connect

    Rezende, Marcos V. dos S.; Valerio, Mário E.G.; Jackson, Robert A.

    2015-01-15

    Highlights: • The effect of different gas atmospheres on the Eu reduction process was studied. • The Eu reduction was monitored analyzing XANES region at the Eu L{sub III}-edge. • Hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization. • Only a part of the Eu ions can be stabilized in the divalent state. • A model of Eu reduction process is proposed. - Abstract: The effect of different gas atmospheres such as H{sub 2}(g), synthetic air, carbon monoxide (CO) and nitrogen (N{sub 2}) on the Eu{sup 3+} → Eu{sup 2+} reduction process during the synthesis of Eu-doped BaAl{sub 2}O{sub 4} was studied using synchrotron radiation. The Eu{sup 3+} → Eu{sup 2+} reduction was monitored analyzing XANES region when the sample are excited at the Eu L{sub III}-edge. The results show that the hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization in BaAl{sub 2}O{sub 4} and that only a part of the Eu ions can be stabilized in the divalent state. A model of Eu reduction process, based on the incorporation of charge compensation defects, is proposed.

  4. Immigration reform, American style.

    PubMed

    Papademetriou, D G

    1984-01-01

    This article reviews the background of the proposed Immigration and Reform Act (also known as the Simpson-Mazzoli bill), which seeks to overhaul US immigration law for the first time since 1952. This bill is consistent with President Reagan's hard line on border enforcement and mandates stiff penalties for those who transport illegal aliens for commercial advantage or private profit. It further offers Mexico preferential treatment in immigration (40,000 additional visas/year). It includes an amnesty program to offer legal status to qualified illegal residents. The bill directs the President to develop a secure national worker identification system and would create a large-scale temporary foreign agricultural program for perishable commodities. Agricultural workers' families would not be eligible to accompany them unless they also obtain temporary visas. Foreign temporary workers, employable only in cases where local domestic workers are not available, must be provided with wages and working conditions equal to those prevailing among domestic workers. Stiff penalties are stipulated for employers who fail to abide with the terms of the program. In the author's opinion, this bill fails to appreciate the global character of international migration and its complexity. It relects a fundamental ambivalence about a strictly controlled main gate versus a back door approach to immigration as well as the conflicting images of the US as a nation of immigrants versus the historical reality of American nativism and xenophobia. Needed are comprehensive initiatives whose mutually reinforcing components can address the multiple dimensions of the immigration problem within a framework that does not ignore workers who have contributed to the economic well-being of the US, regardless of their legal status. PMID:12159575

  5. Reforming Preschools and Schools.

    PubMed

    Duncan, Greg J; Magnuson, Katherine; Murnane, Richard J

    2016-04-01

    Compared with their higher-income counterparts, children growing up in low-income families in the United States typically complete less schooling, report worse health, and work and earn less in adulthood. Moreover, changes in the American economy over the last 40 years have raised the level of skills and qualifications that children need to obtain a good middle-class job, as well as making it much more difficult for children from low-income families to attend schools that support their learning of these skills. We first review strategies used in the past to improve K-12 schooling-including investing more money, introducing more accountability, and putting in place new governance structures (eg, charter schools)-and show why these strategies have been relatively ineffective. Drawing on the research literature and case studies, we then describe education reform strategies for prekindergarten programs and for elementary, middle, and high schools that may help meet these challenges. All of the initiatives described in our case studies provide ample opportunities for teachers and school leaders to improve their skills through coaching and other professional development activities; incorporate sensible systems of accountability, including requiring teachers to open their classrooms to the scrutiny of colleagues and school leaders and to work with their colleagues to improve their teaching practices; and incorporate high academic standards, such as those described in the Common Core State Standards. By focusing directly on improving teaching and promoting learning, these successful initiatives have boosted the achievement of low-income children. They show that it is indeed possible to make a real difference in the life chances of low-income children. PMID:27044689

  6. Photoluminescence properties of Tb-Eu-Mn-codoped fluoroborate glasses under γ-irradiation

    SciTech Connect

    Hari Babu, B.; Ravi Kanth Kumar, V. V.

    2013-09-28

    We report here an energy transfer from Tb{sup 3+} to Eu{sup 3+}, Mn{sup 2+} and Eu{sup 2+} to Tb{sup 3+} and Mn{sup 2+} for an un-irradiated and γ-irradiated B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-Na{sub 2}O-SrF{sub 2} glass samples, respectively. The blue emission from Eu{sup 2+} ions as well as green and red emission from Tb{sup 3+}, Eu{sup 3+}, and Mn{sup 2+} ions will contribute to the generation of white light while excited at 339 nm using a xenon lamp. Furthermore, the chromaticity color coordinates, correlated color temperature, and quantum efficiency parameters are calculated for all the glass samples, and their relative variations with respect to γ-irradiation dose are presented.

  7. Valence fluctuations of europium in the boride Eu4Pd29+x B8

    NASA Astrophysics Data System (ADS)

    Gumeniuk, Roman; Schnelle, Walter; Ahmida, Mahmoud A.; Abd-Elmeguid, Mohsen M.; Kvashnina, Kristina O.; Tsirlin, Alexander A.; Leithe-Jasper, Andreas; Geibel, Christoph

    2016-03-01

    We synthesized a high-quality sample of the boride Eu4Pd29+x B8 (x  =  0.76) and studied its structural and physical properties. Its tetragonal structure was solved by direct methods and confirmed to belong to the Eu4Pd29B8 type. All studied physical properties indicate a valence fluctuating Eu state, with a valence decreasing continuously from about 2.9 at 5 K to 2.7 at 300 K. Maxima in the T dependence of the susceptibility and thermopower at around 135 K and 120 K, respectively, indicate a valence fluctuation energy scale on the order of 300 K. Analysis of the magnetic susceptibility evidences some inconsistencies when using the ionic interconfigurational fluctuation (ICF) model, thus suggesting a stronger relevance of hybridization between 4f and valence electrons compared to standard valence-fluctuating Eu systems.

  8. Photoluminescence properties of Tb-Eu-Mn-codoped fluoroborate glasses under γ-irradiation

    NASA Astrophysics Data System (ADS)

    Hari Babu, B.; Ravi Kanth Kumar, V. V.

    2013-09-01

    We report here an energy transfer from Tb3+ to Eu3+, Mn2+ and Eu2+ to Tb3+ and Mn2+ for an un-irradiated and γ-irradiated B2O3-Al2O3-Na2O-SrF2 glass samples, respectively. The blue emission from Eu2+ ions as well as green and red emission from Tb3+, Eu3+, and Mn2+ ions will contribute to the generation of white light while excited at 339 nm using a xenon lamp. Furthermore, the chromaticity color coordinates, correlated color temperature, and quantum efficiency parameters are calculated for all the glass samples, and their relative variations with respect to γ-irradiation dose are presented.

  9. Valence fluctuations of europium in the boride Eu4Pd(29+x)B8.

    PubMed

    Gumeniuk, Roman; Schnelle, Walter; Ahmida, Mahmoud A; Abd-Elmeguid, Mohsen M; Kvashnina, Kristina O; Tsirlin, Alexander A; Leithe-Jasper, Andreas; Geibel, Christoph

    2016-03-23

    We synthesized a high-quality sample of the boride Eu4Pd(29+x)B8 (x  =  0.76) and studied its structural and physical properties. Its tetragonal structure was solved by direct methods and confirmed to belong to the Eu4Pd29B8 type. All studied physical properties indicate a valence fluctuating Eu state, with a valence decreasing continuously from about 2.9 at 5 K to 2.7 at 300 K. Maxima in the T dependence of the susceptibility and thermopower at around 135 K and 120 K, respectively, indicate a valence fluctuation energy scale on the order of 300 K. Analysis of the magnetic susceptibility evidences some inconsistencies when using the ionic interconfigurational fluctuation (ICF) model, thus suggesting a stronger relevance of hybridization between 4f and valence electrons compared to standard valence-fluctuating Eu systems. PMID:26895077

  10. Bridgman bulk growth and scintillation measurements of SrI2:Eu2+

    NASA Astrophysics Data System (ADS)

    Hawrami, R.; Glodo, J.; Shah, K. S.; Cherepy, N.; Payne, S.; Burger, A.; Boatner, L.

    2013-09-01

    Large diameter Bridgman growth of europium activated strontium iodide SrI2:Eu2+ produces crystals with light yield of up to 115,000 ph/MeV with an excellent light yield proportionality. SrI2:Eu2+ exhibits an outstanding energy resolution of better than 3% FWHM at 662 keV. Its emission is centered at 435 nm. The scintillation decays with a 1 μs time constant for small samples and up to 5 μs to larger crystals. This paper presents successful progress made in the vertical Bridgman crystal growth of SrI2:Eu2+ and its scintillator properties. Large diameter, crack-free and transparent SrI2:Eu2+single crystals with diameters of 1 in., 1.3 in., 1.5 in. and 2 in. were all successfully grown.

  11. Transmittance and optical constants of Eu films from 8.3 to 1400 eV

    SciTech Connect

    Fernandez-Perea, Monica; Vidal-Dasilva, Manuela; Aznarez, Jose A.; Larruquert, Juan I.; Mendez, Jose A.; Poletto, Luca; Garoli, Denis; Malvezzi, A. Marco; Giglia, Angelo; Nannarone, Stefano

    2008-12-15

    The optical constants of Eu films were obtained in the 8.3-1400 eV range from transmittance measurements performed at room temperature. Thin films of Eu were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Eu films were deposited onto grids coated with a thin C support film. The refractive index n of Eu was calculated using the Kramers-Kronig analysis. Data were extrapolated both on the high- and low-energy sides by using experimental and calculated extinction coefficient values available in the literature. Eu, similar to other lanthanides, has a low-absorption band just below the O{sub 2,3} edge onset; the lowest absorption was measured at about 16.7 eV. Therefore, Eu is a promising material for filters and multilayer coatings in the energy range below the O{sub 2,3} edge in which materials typically have a strong absorption. The consistency of the composite optical constants was tested with the f and inertial sum rules and found to be good.

  12. Intramolecular deactivation processes in complexes of salicylic acid or glycolic acid with Eu(III)

    NASA Astrophysics Data System (ADS)

    Kuke, S.; Marmodée, B.; Eidner, S.; Schilde, U.; Kumke, M. U.

    2010-04-01

    The complexation of Eu(III) by 2-hydroxy benzoic acid (2HB) or glycolic acid (GL) was investigated using steady-state and time-resolved laser spectroscopy. Experiments were carried out in H 2O as well as in D 2O in the temperature range of 80KEu(III) luminescence spectra and luminescence decay times were evaluated with respect to the temperature dependence of (i) the luminescence decay time τ, (ii) the energy of the D→F transition, (iii) the width of the D→F transition, and (iv) the asymmetry ratio calculated from the luminescence intensities of the D→F and D→F transition, respectively. The differences in ligand-related luminescence quenching are discussed. Based on the temperature dependence of the luminescence decay times an activation energy for the ligand-specific non-radiative deactivation in Eu(III)-2HB or Eu(III)-GL complexes was determined. It is stressed that ligand-specific quenching processes (other than OH quenching induced by water molecules) need to be determined and considered in detail, in order to extract speciation-relevant information from luminescence data (e.g., estimation of the number of water molecules nO in the first coordination sphere of Eu(III)). In case of 2HB, conclusions drawn from the evaluation of the Eu(III) luminescence are compared with results of a X-ray structure analysis.

  13. Emerging food safety issues: An EU perspective.

    PubMed

    McEvoy, John D G

    2016-05-01

    Safe food is the right of every citizen of the European Union (EU). A comprehensive and dynamic framework of food and feed safety legislation has been put in place and the EU's executive arm - the European Commission - is responsible for ensuring that the EU member states apply food law consistently. Similarly, the Commission plays an important role in ensuring that imported food meets the EU's stringent food safety standards. Consumer perceptions of unsafe food tend to focus on acute outbreaks of bacterial or viral origin. In recent years there have been a number of diverse food crises associated with fraudulent activity which may (e.g. melamine in dairy products in China) or may not (e.g. the horse meat scandal in the EU) represent a genuine food safety risk. Well publicized incidents of chronic exposure to chemical contamination in the EU (e.g. dioxins in meat and mycotoxins in nuts) have required robust coordinated policy responses from the Commission. Despite the decreasing incidence of non-compliant residues of veterinary medicinal products and banned substances in animal products, EU consumers are increasingly concerned about the use of such products in food-producing animals, including in the context of the build-up of antimicrobial resistance in animals and transfer to humans. The Commission plays a key role in coordination of the EU member states' responses to such incidents, in risk management, and in preparation for emerging issues. This paper focuses on how the EU as a whole has dealt with a number of food crises, and what can be learned from past incidents. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27443205

  14. Out-of-Plane Disorder Effects on the Energy Gaps and Electronic Charge Order in Bi2Sr1.7R0.3CuO6+δ (R = La and Eu)

    NASA Astrophysics Data System (ADS)

    Kurosawa, Tohru; Takeyama, Kohsaku; Baar, Stefan; Shibata, Yuto; Kataoka, Moeko; Mizuta, Shusei; Yoshida, Hiroshi; Momono, Naoki; Oda, Migaku; Ido, Masayuki

    2016-04-01

    We performed STM/STS experiments at 8 K in Bi2Sr1.7R0.3CuO6+δ (R-Bi2201) systems that had optimal (OP) hole-doping levels (˜0.17) but different Tc values, 35 K for R = La and 20 K for R = Eu, and examined out-of-plane disorder effects on the superconducting (SC) gap (SCG) and the pseudogap (PG) which is associated with the so-called "checkerboard charge order" (CCO). As out-of-plane disorders are strengthened by replacing La with Eu in OP R-Bi2201, the antinodal PG size ΔPG increases from ˜30 to ˜60 meV, the nodal SCG size ΔSC seems to decrease from ˜7 to ˜4 meV, and the pairing gap amplitude Δ0 or d-wave gap size at the antinodes is almost unchanged (Δ0 ˜ 15 meV). These gap sizes for OP doping in Eu-Bi2201 are comparable to those for an underdoping level of ˜0.1 in La-Bi2201. Although out-of-plane disorders strongly affect the electronic system of the Cu-O plane, they have no effect on the period of the CCO, which is five times the lattice constant (5a) along the Cu-O bond directions for OP doping and 4a for p ˜ 0.1. We suggest that the concentration of holes doped into the Cu-O plane may be an essential factor for determining the period of the CCO.

  15. Public Sector Reform in Australia and Its Impact on Libraries.

    ERIC Educational Resources Information Center

    Willard, Patricia

    1995-01-01

    Provides an overview of public sector reform in Australia, focusing on the Commonwealth Government and Australian Public Service. Describes management reform packages, human resources management reforms, and industrial relations reforms. Discusses the impact of these changes on public libraries. (AEF)

  16. Health Care Reform: Out Greatest Opportunity...Ever!

    ERIC Educational Resources Information Center

    Keigher, Sharon M.

    1993-01-01

    Discusses inevitability of health care reform in United States, considers the reform process itself, and explains the plan of the President's Task Force on National Health Care Reform. Also considers the prospects for Congressional response to reform proposals. (NB)

  17. Synthesis and characterization of Eu{sup 3+}-doped CaZrO{sub 3}-based perovskite-type phosphors. Part I: Determination of the Eu{sup 3+} occupied site using the ALCHEMI technique

    SciTech Connect

    Sakaida, Satoshi; Shimokawa, Yohei; Asaka, Toru; Honda, Sawao; Iwamoto, Yuji

    2015-07-15

    Highlights: • Eu{sup 3+}-doped CaZrO{sub 3}-based compounds were synthesized by the solid state reaction. • PL emission intensity at 614 nm was changed by the second dopant cations. • The site substituted by Eu{sup 3+} cations was investigated by using XRD and ALCHEMI technique. • The dominant Eu{sup 3+} substitution site was found as the B site (Zr{sup 4+}) in the CaZrO{sub {sup 3}}. • The dominant Eu{sup 3+} substitution site could be strongly influenced by the co-dopants. - Abstract: Eu{sup 3+}-doped CaZrO{sub 3}, SrZrO{sub 3}, and Mg{sup 2+}- or Sr{sup 2+}-co-doped CaZrO{sub 3} were synthesized by conventional solid state reaction and their photoluminescence (PL) properties were characterized. The Eu{sup 3+}-doped CaZrO{sub 3}-based compounds exhibited characteristic emissions of Eu{sup 3+} (f–f transition). The intensity of the main PL emission peak at 614 nm increased with Mg{sup 2+} co-doping, while it decreased with the amount of co-doped Sr{sup 2+}. The site substituted by Eu{sup 3+} cations in the CaZrO{sub 3}-based compounds was investigated by X-ray diffraction analysis and energy-dispersive X-ray analysis based on the electron channeling effects in transmission electron microscopy. The Eu{sup 3+} cations were determined to occupy mainly the B site (Zr{sup 4+}) in CaZrO{sub 3}. The dominant Eu{sup 3+} substitution site was also strongly influenced by the co-dopant, and the ionic radius of the co-dopant was identified as an important factor that determines the dominant Eu{sup 3+} substitution site.

  18. Direct white-light from core-shell-like sphere with Sr3Mg-Si2O8: Eu2+, Mn2+ coated on Sr2SiO4:Eu2+

    NASA Astrophysics Data System (ADS)

    Li, Jian; Deng, Jia-chun; Lu, Qi-fei; Wang, Da-jian

    2013-07-01

    A method of color mixture for white light is presented with Sr3MgSi2O8:Eu2+, Mn2+ shell coated on Sr2SiO4:Eu2+ core by spray pyrolysis procedure. Upon near ultraviolet (NUV) excitation, a 550 nm band emission of Eu2+ from core host combines with the simultaneous emissions of Eu2+ at 457 nm and Mn2+ at 683 nm based on energy transfer in the shell lattice to generate warm white light with color rendering index (CRI) of 91. With such a core-shell-like structure, the re-absorption of blue light from shell layer can be effectively suppressed, and the chemical stability of the phosphor is verified experimentally to be superior to that of the Sr2SiO4:Eu2+. This new proposed phosphor provides great potential in the color mixture of blending-free phosphor converted white NUV light emitting diode (LED) devices.

  19. Bringing electricity reform to the Philippines

    SciTech Connect

    Fe Villamejor-Mendoza, Maria

    2008-12-15

    Electricity reforms will not translate to competition overnight. But reforms are inching their way forward in institutions and stakeholders of the Philippine electricity industry, through regulatory and competition frameworks, processes, and systems promulgated and implemented. (author)

  20. Health care reform: informing difficult choices.

    PubMed

    Maynard, A; Bloor, K

    1995-01-01

    During the last decade, policy makers in a large number of countries have attempted various reforms of their health care systems. Health care reform has been described as a 'global epidemic' (Klein, 1993). All health care reforms consist of very complex policy choices, some of which are examined in this article. After an introductory exploration of ideological issues, the objectives of health care reformers are considered. Three major policy objectives of health care reform are examined: cost containment; efficiency; and, equity. Three types of reform which have been advocated are also considered: public planning; market regulation; and provider-advocated reforms such as a 'basic package' with copayments and alternative means of finance. Finally, appropriate features of efficient health care reform are suggested, addressing explicit policy goals. PMID:10154305

  1. Attrition resistant fluidizable reforming catalyst

    DOEpatents

    Parent, Yves O.; Magrini, Kim; Landin, Steven M.; Ritland, Marcus A.

    2011-03-29

    A method of preparing a steam reforming catalyst characterized by improved resistance to attrition loss when used for cracking, reforming, water gas shift and gasification reactions on feedstock in a fluidized bed reactor, comprising: fabricating the ceramic support particle, coating a ceramic support by adding an aqueous solution of a precursor salt of a metal selected from the group consisting of Ni, Pt, Pd, Ru, Rh, Cr, Co, Mn, Mg, K, La and Fe and mixtures thereof to the ceramic support and calcining the coated ceramic in air to convert the metal salts to metal oxides.

  2. Florence Nightingale and healthcare reform.

    PubMed

    Kudzma, Elizabeth Connelly

    2006-01-01

    The purpose of this article was to examine the work of Florence Nightingale in light of her collaboration with William Farr, the eminent medical statistician. Nightingale's epidemiological investigations supported by Farr illustrated that attention to environmental cleanliness was an important factor in preventing spread of disease. Nightingale channeled her investigations to support hospital reforms and the need for an educated nurse who could provide better management of the hospital environment. Statistical support and solicited criticism allowed Nightingale to argue more forcefully for her reforms. PMID:16407602

  3. Method of steam reforming methanol to hydrogen

    DOEpatents

    Beshty, Bahjat S.

    1990-01-01

    The production of hydrogen by the catalyzed steam reforming of methanol is accomplished using a reformer of greatly reduced size and cost wherein a mixture of water and methanol is superheated to the gaseous state at temperatures of about 800.degree. to about 1,100.degree. F. and then fed to a reformer in direct contact with the catalyst bed contained therein, whereby the heat for the endothermic steam reforming reaction is derived directly from the superheated steam/methanol mixture.

  4. The National School Reform Faculty: Reforming Schools from the Inside

    ERIC Educational Resources Information Center

    Educational Horizons, 2005

    2005-01-01

    In the Winter 2005 issue of "educational HORIZONS," Charles Glenn wrote that schools designed in a perfect system of educational diversity and choice could nonetheless end up as "uninspired carbon copies produced by educators without the foggiest idea of how to do anything differently." Most school reform tries to avoid that fate with various…

  5. Oncology payment reform to achieve real health care reform.

    PubMed

    McClellan, Mark B; Thoumi, Andrea I

    2015-05-01

    Cancer care is transforming, moving toward increasingly personalized treatment with the potential to save and improve many more lives. Many oncologists and policymakers view current fee-for-service payments as an obstacle to providing more efficient, high-quality cancer care. However, payment reforms create new uncertainties for oncologists and may be challenging to implement. In this article, we illustrate how accountable care payment reforms that directly align payments with quality and cost measures are being implemented and the opportunities and challenges they present. These payment models provide more flexibility to oncologists and other providers to give patients the personalized care they need, along with more accountability for demonstrating quality improvements and overall cost or cost growth reductions. Such payment reforms increase the importance of person-level quality and cost measures as well as data analysis to improve measured performance. We describe key features of quality and cost measures needed to support accountable care payment reforms in oncology. Finally, we propose policy recommendations to move incrementally but fundamentally to payment systems that support higher-value care in oncology. PMID:25901049

  6. Reformers and Reform: Towards Free Public Libraries in Victoria

    ERIC Educational Resources Information Center

    Barker, Donald

    2007-01-01

    The "Victorian Free Library Service Board Act" of 1946 was the culmination of a long campaign to replace the mechanics' institute model of library provision with free libraries funded by state and local government. Given that library reform required legislation by the state government, this paper is mainly concerned with the political campaign…

  7. Reel Reform: Documentaries Spur Debate about Educational Reform

    ERIC Educational Resources Information Center

    Hurley, Stephen

    2011-01-01

    Three new American documentaries including "Waiting for Superman," "The Lottery, Race to Nowhere" and one British entry, "We are the People We've Been Waiting For," have animated school reform debates. Each of these documentaries seeks to disturb the entrenched thinking by claiming that our educational institutions are suffering from a malaise…

  8. Spectroscopic studies on interaction of BSA and Eu(III) complexes with H5ph-dtpa and H5dtpa ligands

    NASA Astrophysics Data System (ADS)

    Kong, Deyong; Qin, Cui; Fan, Ping; Li, Bing; Wang, Jun

    2015-04-01

    An novel aromatic aminopolycarboxylic acid ligand, N-(2-N,N-Dicarboxymethylaminophenyl) ethylenediamine-N,N‧,N‧-triacetic acid (H5ph-dtpa), was synthesized by improving experimental method and its corresponding Eu(III) complex, Na2[EuIII(ph-dtpa)(H2O)]·6H2O, was successfully prepared through heat-refluxing method. As a comparison, the Eu(III) complex with diethylenetriamine-N,N,N‧,N‧,N″-pentaacetic acid (H5dtpa) ligand, Na2[EuIII(dtpa)(H2O)]·6H2O, was also prepared by the same method. And then, the interaction between prepared Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and bovine serum albumin (BSA) in aqueous solution were studied by the combination of ultraviolet-visible (UV-vis), fluorescence and circular dichroism (CD) spectroscopies. In addition, the binding sites of Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) to BSA molecules were also estimated by synchronous fluorescence. Moreover, the theoretical and experimental results show that the Van der Waals, hydrogen bond and π-π stacking interactions are the mainly impulse to the reaction. The binding distances (r) between Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and BSA were obtained according to Förster's non-radiative energy transfer theory. Also, the determined UV-vis absorption spectroscopy, synchronous fluorescence and circular dichroism (CD) spectra showed that the conformation of BSA could be changed in the presence of Eu(III) complexes. The obtained results can help understand the action mode between rare earth metal complexes of aminopolycarboxylic acid ligands with BSA and they are also expected to provide important information of designs of new inspired drugs.

  9. Antiferromagnetism in EuNiGe3

    SciTech Connect

    Goetsch, R. J.; Ananad, V. K.; Johnston, David C.

    2013-02-07

    The synthesis and crystallographic and physical properties of polycrystalline EuNiGe3 are reported. EuNiGe3 crystallizes in the noncentrosymmetric body-centered tetragonal BaNiSn3-type structure (space group I4mm), in agreement with previous reports, with the Eu atoms at the corners and body center of the unit cell. The physical property data consistently demonstrate that this is a metallic system in which Eu spins S = 7/2 order antiferromagnetically at a temperature TN = 13.6 K.Magnetic susceptibility χ data forT >TN indicate that the Eu atoms have spin 7/2 with g = 2, that the Ni atoms are nonmagnetic, and that the dominant interactions between the Eu spins are ferromagnetic. Thus we propose that EuNiGe3 has a collinear A-type antiferromagnetic structure, with the Eu ordered moments in the ab plane aligned ferromagnetically and with the moments in adjacent planes along the c axis aligned antiferromagnetically. A fit of χ(T TN) by our molecular field theory is consistent with a collinear magnetic structure. Electrical resistivity ρ data from TN to 350 K are fitted by the Bloch-Gr¨uneisen model for electron-phonon scattering, yielding a Debye temperature of 265(2) K.Astrong decrease in ρ occurs belowTN due to loss of spin-disorder scattering. Heat capacity data at 25 K T 300Kare fitted by the Debye model, yielding the same Debye temperature 268(2) K as found from ρ(T ). The extracted magnetic heat capacity is consistent with S = 7/2 and shows that significant short-range dynamical spin correlations occur above TN. The magnetic entropy at TN = 13.6 K is 83% of the expected asymptotic high-T value, with the remainder recovered by 30 K.

  10. Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

    PubMed

    Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

    2016-09-01

    Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field. PMID:27494550

  11. 49 CFR 260.13 - Credit reform.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Credit reform. 260.13 Section 260.13... REHABILITATION AND IMPROVEMENT FINANCING PROGRAM Overview § 260.13 Credit reform. The Federal Credit Reform Act of 1990, 2 U.S.C. 661, requires Federal agencies to set aside the subsidy cost of new...

  12. 49 CFR 260.13 - Credit reform.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Credit reform. 260.13 Section 260.13... REHABILITATION AND IMPROVEMENT FINANCING PROGRAM Overview § 260.13 Credit reform. The Federal Credit Reform Act of 1990, 2 U.S.C. 661, requires Federal agencies to set aside the subsidy cost of new...

  13. 49 CFR 260.13 - Credit reform.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Credit reform. 260.13 Section 260.13... REHABILITATION AND IMPROVEMENT FINANCING PROGRAM Overview § 260.13 Credit reform. The Federal Credit Reform Act of 1990, 2 U.S.C. 661, requires Federal agencies to set aside the subsidy cost of new...

  14. 49 CFR 260.13 - Credit reform.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Credit reform. 260.13 Section 260.13... REHABILITATION AND IMPROVEMENT FINANCING PROGRAM Overview § 260.13 Credit reform. The Federal Credit Reform Act of 1990, 2 U.S.C. 661, requires Federal agencies to set aside the subsidy cost of new...

  15. 49 CFR 260.13 - Credit reform.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Credit reform. 260.13 Section 260.13... REHABILITATION AND IMPROVEMENT FINANCING PROGRAM Overview § 260.13 Credit reform. The Federal Credit Reform Act of 1990, 2 U.S.C. 661, requires Federal agencies to set aside the subsidy cost of new...

  16. General Education Reform: Opportunities for Institutional Alignment

    ERIC Educational Resources Information Center

    Fuess, Scott M., Jr.; Mitchell, Nancy D.

    2011-01-01

    General education reform provides strategic opportunities for departments. This article analyzes reform at the University of Nebraska-Lincoln, illustrating how departments could use the reform process to clarify their strategic planning, align with institutional goals, and steer the university closer to departmental objectives. (Contains 1 table.)

  17. Reform and Transform with the Arts

    ERIC Educational Resources Information Center

    Wilson, Mark

    2009-01-01

    When school leaders think of reform, their first thought is rarely "the arts," but perhaps they've been missing a vehicle that can inspire the adoption of best practices on a schoolwide basis. School leaders across Georgia are using the arts in the core reform areas that were recommended in "Breaking Ranks II: Strategies for High School Reform" as…

  18. Large-Scale Reform Comes of Age

    ERIC Educational Resources Information Center

    Fullan, Michael

    2009-01-01

    This article reviews the history of large-scale education reform and makes the case that large-scale or whole system reform policies and strategies are becoming increasingly evident. The review briefly addresses the pre 1997 period concluding that while the pressure for reform was mounting that there were very few examples of deliberate or…

  19. Leadership Lessons from Comprehensive School Reforms.

    ERIC Educational Resources Information Center

    Murphy, Joseph, Ed.; Datnow, Amanda, Ed.

    This volume explores the role of leadership in comprehensive school reform (CSR). It consists of 12 chapters: (1) "The Development of Comprehensive School Reform" (Joseph Murphy and Amanda Datnow); (2) "Expeditionary Learning Schools: Tenacity, Leadership, and School Reform" (Greg Farrell); (3) "The Modern Red School House: Leadership in…

  20. School Reform--Does It Really Matter?

    ERIC Educational Resources Information Center

    Bunting, Carolyn

    1999-01-01

    Looks at different waves of school reform beginning with Sputnik in the 1950s. Examines influences in today's reform, including industrial influences and school choice. Argues that the origins and outcomes of school reform have more to do with what is happening outside the school than within it, and that schools must think beyond objective indices…

  1. Considerations for Education Reform in British Columbia

    ERIC Educational Resources Information Center

    Santos, Ana

    2012-01-01

    Countries around the world refer to twenty-first century education as essential to maintaining personal and national economic advantage and draw on this discourse to advocate for and embark on educational reform. This paper examines issues around education reform, particularly in British Columbia. It argues that reformers should give careful…

  2. Whatever Happened to Undergraduate Reform? Carnegie Perspectives

    ERIC Educational Resources Information Center

    Marchese, Theodore J.

    2006-01-01

    The author asks whether higher education reform has run out of new things to say. The final two decades of the twentieth century were a remarkable period for innovation in undergraduate education. Many of higher education's earlier waves of reform had focused on curricular issues, on what should be taught. The new reformers by and large ignored…

  3. Funding Comprehensive School Reform. Rand Issue Paper.

    ERIC Educational Resources Information Center

    Keltner, Brent R.

    Comprehensive school reform is a type of reform process directed at primary and secondary education that relies on the simultaneous change of all elements of a school's operating environment aligned with a central, guiding vision. This new approach was developed in response to the growing dissatisfaction with the traditional piecemeal reform,…

  4. Assessing Students' Conceptions of Reform Mathematics.

    ERIC Educational Resources Information Center

    Star, Jon R.; Hoffmann, Amanda J.

    As the use of National Science Foundation (NSF)-sponsored, reform- oriented mathematics curricula has become more prevalent across the U.S., an increasing number of researchers are attempting to study the "impact" of reform. In particular, mathematics educators are interested in determining whether reforms are having the desired effects on…

  5. Community Organizing as an Education Reform Strategy

    ERIC Educational Resources Information Center

    Renee, Michelle; McAlister, Sara

    2011-01-01

    Community organizing for school reform offers an urgently needed alternative to traditional approaches to school change. Many current reforms fail to thrive due to lack of trust, understanding, or cultural relevance to the community being targeted. The high turnover of reformers (superintendents, principals, or outside organizations) in high-need…

  6. Globalization and Educational Reform in Contemporary Japan

    ERIC Educational Resources Information Center

    Qi, Jie; Zhang, Sheng Ping

    2008-01-01

    This study explores the notions of globalization as embodied in Japanese educational reforms. Modern institutional discourses of educational reform in Japan have shifted over time and all of these reform movements have been constructed by particular social and historical trajectories. Generally speaking, it has been taken for granted that the…

  7. Systemic Reform--Monitoring Its Progress.

    ERIC Educational Resources Information Center

    Gregg, Soleil

    1992-01-01

    This paper discusses a series of questions that state policymakers can use to assess the systemic nature of their education reform efforts. Suggestions are offered for identifying the evidence of scope, coherence, and balance of reform. To assess the scope of reform, a first step is to determine if the performance-based standards provide the…

  8. Whose Job Is It to Lead Reform?

    ERIC Educational Resources Information Center

    McAdams, Donald R.

    2004-01-01

    Much confusion exists today among board of education members and superintendents about governance roles, especially when a district is low performing and the public is demanding bold reform. Part of the confusion comes from the definition of reform. To many Americans, school reform means fine-tuning what education historian David B. Tyack calls…

  9. Catalog of School Reform Models. Program Report.

    ERIC Educational Resources Information Center

    Buechler, Mark

    Comprehensive school reform involves changes in every aspect of school operations, from classroom instruction to school governance. Some schools develop their own reform approach from within. Others seek assistance from without, particularly from organizations that have developed coherent, research-based approaches, or school-reform models. For…

  10. School Reform and Schools as Organizations.

    ERIC Educational Resources Information Center

    Willower, Donald J.

    1991-01-01

    Schools' characteristics obstruct reform because teacher and student norms and values are at variance with one another. Because most reforms gobble teacher time, reduce teacher autonomy, and disturb current routines, they frequently fail. Chances for success will improve when context or reforms directly addressing organizational features are…

  11. Governance Reform at China's "985 Project" Universities

    ERIC Educational Resources Information Center

    Qingnian, Xiong; Duanhong, Zhang; Hong, Liu

    2011-01-01

    Higher education reform in China is deepening, and the governance reform taking place at the 985 Project universities over the past decade has displayed a shift from government driven to internally driven, from adaptive to proactive, and from localized to systemic. This reflects the overall status of governance reform in China's higher education.…

  12. Scintillation properties of Eu2+-doped KBa2I5 and K2BaI4

    DOE PAGESBeta

    Stand, L.; Zhuravleva, M.; Chakoumakos, Bryan C.; Johnson, J.; Lindsey, Adam; Melcher, Charles L.

    2015-09-25

    We report two new ternary metal halide scintillators, KBa2I5 and K2BaI4, activated with divalent europium. Single crystal X-ray diffraction measurements confirmed that KBa2I5 has a monoclinic structure (P21/c) and that K2BaI4 has a rhombohedral structure (R3c). Differential scanning calorimetry showed singular melting and crystallization points, making these compounds viable candidates for melt growth. We grew 13 mm diameter single crystals of KBa2I5:Eu2+ and K2BaI4:Eu2+ in evacuated quartz ampoules via the vertical Bridgman technique. The optimal Eu2+ concentration was 4% for KBa2I5 and 7% for K2BaI4. The X-ray excited emissions at 444 nm for KBa2I5:Eu 4% and 448 nm for K2BaI4:Eumore » 7% arise from the 5d-4f radiative transition in Eu2+. KBa2I5:Eu 4% has a light yield of 90,000 photons/MeV, with an energy resolution of 2.4% and K2BaI4:Eu 7% has a light yield of 63,000 ph/MeV, with an energy resolution of 2.9% at 662 keV. Both crystals have an excellent proportional response to a wide range of gamma-ray energies.« less

  13. Role of oxygen vacancy on the photoluminescence of BaMgSiO4:Eu phosphors: experimental and theoretical analysis.

    PubMed

    Ji, Weiwei; Lee, Ming-Hsien; Hao, Luyuan; Xu, Xin; Agathopoulos, Simeon; Zheng, Dewen; Fang, Chaohe

    2015-02-16

    Pure BaMgSiO4:Eu(2+) phosphor, prepared by a solid state reaction method under N2 atmosphere, exhibited a strong green emission at 500 nm and a weak emission at 405 nm. Heat treatment under NH3 atmosphere causes changes in the PL intensity: the green emission at 500 nm gradually decreases and completely disappears after heat treatment for 3 h, whereas a new blue emission peak, centered at 445 nm, appears and becomes very strong. The results of the analyses with electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) spectroscopy suggest that the heat treatment causes the generation of a large amount of oxygen vacancies. This resulted in the aforementioned color changes of the BaMgSiO4:Eu phosphor, which are confirmed by the results of DFT+U calculations. In particular, these calculations showed that Eu prefers to occupy Ba(3) sites, which are six coordinated to oxygen atoms. The emission at 500 nm was attributed to the 4f-5d transition energy of Eu in Ba(3) site, calculated as 2.54 eV. It was also shown that Eu 4f energy level decreases when oxygen is removed from the oxygen position adjacent to Eu, which results in a larger Eu 4f-5d transition energy and shorter wavelengths of emission peaks. PMID:25642733

  14. Luminescence Enhanced Eu(3+)/Gd(3+) Co-Doped Hydroxyapatite Nanocrystals as Imaging Agents In Vitro and In Vivo.

    PubMed

    Xie, Yunfei; He, Wangmei; Li, Fang; Perera, Thalagalage Shalika Harshani; Gan, Lin; Han, Yingchao; Wang, Xinyu; Li, Shipu; Dai, Honglian

    2016-04-27

    Biocompatible, biodegradable, and luminescent nano material can be used as an alternative bioimaging agent for early cancer diagnosis, which is crucial to achieve successful treatment. Hydroxyapatite (HAP) nanocyrstals have good biocompatibility and biodegradability, and can be used as an excellent host for luminescent rare earth elements. In this study, based on the energy transfer from Gd(3+) to Eu(3+), the luminescence enhanced imaging agent of Eu/Gd codoping HAP (HAP:Eu/Gd) nanocrystals are obtained via coprecipitation with plate-like shape and no change in crystal phase composition. The luminescence can be much elevated (up to about 120%) with a nonlinear increase versus Gd doping content, which is due to the energy transfer ((6)PJ of Gd(3+) → (5)HJ of Eu(3+)) under 273 nm and the possible combination effect of the cooperative upconversion and the successive energy transfer under 394 nm, respectively. Results demonstrate that the biocompatible HAP:Eu/Gd nanocrystals can successfully perform cell labeling and in vivo imaging. The intracellular HAP:Eu/Gd nanocrystals display good biodegradability with a cumulative degradation of about 65% after 72 h. This biocompatible, biodegradable, and luminescence enhanced HAP:Eu/Gd nanocrystal has the potential to act as a fluorescent imaging agent in vitro and in vivo. PMID:27043792

  15. Electrospinning preparation and photoluminescence properties of poly (methyl methacrylate)/Eu{sup 3+} ions composite nanofibers and nanoribbons

    SciTech Connect

    Li, Maoying; Zhang, Zhenyi; Cao, Tieping; Sun, Yangyang; Liang, Pingping; Shao, Changlu; Liu, Yichun

    2012-02-15

    Graphical abstract: Nanofibers and nanoribbons of poly (methyl methacrylate)/Eu{sup 3+} ions composites were successfully prepared by using a simple electrospinning technique. And the photoluminescence properties of the above PMMA/Eu{sup 3+} ions composites were studied. Highlights: Black-Right-Pointing-Pointer Nanofibers and nanoribbons of PMMA/Eu{sup 3+} ions composites are fabricated by electrospinning. Black-Right-Pointing-Pointer Photoluminescence properties of as-electrospun PMMA/Eu{sup 3+} ions composites are studied. Black-Right-Pointing-Pointer The ratios of electric- and magnetic-dipole transitions are enhanced by increasing electrospinning voltage. -- Abstract: Nanofibers and nanoribbons of poly (methyl methacrylate) (PMMA)/Eu{sup 3+} ions composites with different concentration of Eu{sup 3+} ions were successfully prepared by using a simple electrospinning technique. From the results of scanning electron microscopy and energy-dispersive X-ray spectroscopy, we found that the morphology of the as-electrospun PMMA/Eu{sup 3+} ions composites could be changed from fiber to ribbon structure by adjusting the concentration of Eu{sup 3+} ions in the electrospun precursor solution. The coordination between the Eu{sup 3+} ions and PMMA molecules were investigated by Fourier transform infrared spectroscopy and differential thermal analysis. The photoluminescence (PL) properties of the as-electrospun PMMA/Eu{sup 3+} ions composites were studied in comparison to those of the Eu(NO{sub 3}){sub 3} powder. It was showed that the {sup 5}D{sub 0}-{sup 7}F{sub J} (J = 0, 1, 2, 3, 4) emission appeared in the PL spectra of the as-electrospun PMMA/Eu{sup 3+} ions composites, whereas the {sup 5}D{sub 0}-{sup 7}F{sub 0} emission was completely absent in the PL spectra of Eu(NO{sub 3}){sub 3} powder due to the different local environments surrounding Eu{sup 3+} ions. It was interesting to note that the intensity ratios of the electric-dipole and magnetic-dipole transitions for

  16. Dopant concentration dependent optical and X-Ray induced photoluminescence in Eu3+ doped La2Zr2O7

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab; Brik, Mikhail; Mao, Yuanbing

    2015-03-01

    Herein, we will be presenting the dopant (Eu) concentration dependent high density La2Zr2O7 nanoparticles for optical and X-ray scintillation applications by use of X - ray diffraction, Raman, FTIR, scanning electron microscope (SEM), transmission electron microscopy (TEM), optically and X-ray excited photoluminescence (PL). Several theoretical methods have been used in order to investigate the structural, electronic, optical, elastic, dynamic properties of Eu doped La2Zr2O7. It is observed that Eu: La2Zr2O7 shows an intense red luminescence under 258, 322, 394 and 465 nm excitation. The optical intensity of Eu: La2Zr2O7 depends on the dopant concentration of Eu3+. Following high energy excitation with X-rays, Eu: La2Zr2O7 shows an atypical Eu PL response (scintillation) with a red emission. The intense color emission of Eu obtained under 258 nm excitation, the X-ray induced luminescence property along with reportedly high density of La2Zr2O7, makes these nanomaterials attractive for optical and X-ray applications. The authors thank the support from the Defense Threat Reduction Agency (DTRA) of the U.S. Department of Defense (Award #HDTRA1-10-1-0114).

  17. Synthesis of Y 2O 3:Eu phosphors by bicontinuous cubic phase process

    NASA Astrophysics Data System (ADS)

    Chien, Wen-Chen

    2006-05-01

    A novel approach for preparation of red-emitting europium-doped yttrium oxide phosphor (Y 2O 3:Eu) by using the bicontinuous cubic phase (BCP) process was reported in this paper. The BCP system was composed of anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and aqueous yttrium nitrate/europium nitrate solution. Energy dispersive spectrometer analysis revealed the homogeneous precipitation occurred in the BCP structure. Thermogravimetric analysis measurements indicated the precursor powder was europium-doped yttrium hydroxide, Y 1-xEu x(OH) 3. Scanning electron microscopy micrographs showed the precursor powder had a primary size about 30 nm and narrow size distribution. After heat treatment in furnace above 700 °C for 4 h, high crystallinity Y 2O 3:Eu phosphors was obtained. However, the primary size of particles grew to 50-200 nm and the dense agglomerates with a size below 1 μm were formed. X-ray diffraction patterns indicated the crystal structure of precursor powders and Y 2O 3:Eu phosphors were amorphous and body-centered cubic structure, respectively. The photoluminescence analysis showed that the obtained Y 2O 3:Eu phosphor had a strong red emitting at 612 nm and the quenching started at a Eu concentration of 10 mol%. This study indicated that the BCP process could be used to prepare the highly efficient oxide-based phosphors.

  18. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance

    SciTech Connect

    Moore, Evan G.; D'Aleo, Anthony; Xu, Jide; Raymond, Kenneth N.

    2009-05-29

    The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV-visible and then efficiently transfer the energy to the lanthanoid centre. The synthesis and the complexation of Ln{sup III} cations (Ln = Eu, Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu{sup III} complex ([Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}) has been evaluated in terms of its thermodynamic stability, UV-visible absorption and luminescence properties. For this complex, the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid at pH = 7.4. This Eu{sup III} complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH = 7.4) when compared with other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}. This overall improvement was achieved by saturating the coordination sphere of the Eu{sup III} cation, yielding an increased metal-centred efficiency by excluding solvent water molecules from the metal's inner sphere.

  19. Citrate-Complexation Synthesis and Photoluminescence Properties of Y6MoO12:Eu Nanocrystalline.

    PubMed

    Li, Huaiyong; Pu, Xipeng; Yao, Shujuan; Wang, Xiaoqing; Noh, Hyeon Mi; Jeong, Jung Hyun

    2016-04-01

    Y6MoO12 doped with Eu3+ was synthesized using a citrate-complexation route, and was calcined at 800 °C and 1400 °C, respectively. The structure, morphology and photoluminescence (PL) properties of the samples, and their dependence on the crystallite size were investigated. XRD patterns indicate that the Y6MoO12:Eu3+ powder was obtained at both calcination temperatures, and had a cubic structure. The results also suggest that Y6MoO12:Eu3+ calcined at 800 °C was in the nanocrystalline phase, which was confirmed by the SEM microimage. The crystalline size was about 140 nm. Both phosphors could be excited via three channels: f-f excitation of Eu3+ by blue light, MoO groups excitation by near-UV light, and charge transfer state excitation of Eu3+ by UV light. Both samples yielded red light emissions dominated by the 5D0-7F2 transition at 613 nm. The excitation efficient of the three channels depended on the calcination temperature. The energy transfer from the MoO groups to the Eu3+ ions was more effective in the nanocrystalline phase. The temporal decay feature of the phosphor was also characterized. PMID:27451680

  20. Photoluminescence and thermoluminescence characteristics of Sr3 B2 O6 :Eu(2+) yellow phosphor.

    PubMed

    Ho Van, Tuyen; Nguyen Manh, Son; Vu Xuan, Quang; Bounyavong, Sengthong

    2016-08-01

    Sr3 B2 O6 :Eu(2+) yellow phosphor was prepared by the combustion method. The crystalline structure, photoluminescence and thermoluminescence properties of Sr3 B2 O6 :Eu(2+) were investigated extensively. The X-ray diffraction result indicates that the Sr3 B2 O6 :Eu(2+) phosphor exhibited a rhombohedral crystal structure. The emission spectra under a 435 nm excited wavelength showed an intense broad band peaking at 574 nm, which corresponds to the 4f(6) 5d(1) → 4f(7) transition of Eu(2+) ion. There were two different sites of Sr replaced by Eu in host lattice. The concentration quenching process between Eu(2+) ions is determined and the corresponding concentration quenching mechanism was verified as dipole-quadrupole interaction. The glow curve under 3 Gy β- ray irradiation had the glow peak at 160°C and the average activation energy was defined as about 0.98 eV. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26669720

  1. Tuning Eu3+ emission in europium sesquioxide films by changing the crystalline phase

    NASA Astrophysics Data System (ADS)

    Mariscal, A.; Quesada, A.; Camps, I.; Palomares, F. J.; Fernández, J. F.; Serna, R.

    2016-06-01

    We report the growth of europium sesquioxide (Eu2O3) thin films by pulsed laser deposition (PLD) in vacuum at room temperature from a pure Eu2O3 ceramic bulk target. The films were deposited in different configurations formed by adding capping and/or buffer layers of amorphous aluminum oxide (a-Al2O3). The optical properties, refractive index and extinction coefficient of the as deposited Eu2O3 layers were obtained. X-ray photoelectron spectroscopy (XPS) measurements were done to assess its chemical composition. Post-deposition annealing was performed at 500 °C and 850 °C in air in order to achieve the formation of crystalline films and to accomplish photoluminescence emission. According to the analysis of X-ray diffraction (XRD) spectra, cubic and monoclinic phases were formed. It is found that the relative amount of the phases is related to the different film configurations, showing that the control over the crystallization phase can be realized by adequately designing the structures. All the films showed photoluminescence emission peaks (under excitation at 355 nm) that are attributed to the intra 4f-transitions of Eu3+ ions. The emission spectral shape depends on the crystalline phase of the Eu2O3 layer. Specifically, changes in the hypersensitive 5D0 → 7F2 emission confirm the strong influence of the crystal field effect on the Eu3+ energy levels.

  2. Time-resolved luminescence studies of Eu3+ in soda-lime silicate glasses

    NASA Astrophysics Data System (ADS)

    Ruivo, Andreia; Muralha, Vânia S. F.; Águas, Hugo; de Matos, António Pires; Laia, César A. T.

    2014-02-01

    Soda-lime glasses doped with Eu3+ were synthesized using a variety of compositions, namely changing the fraction of CaO or Eu2O3. Those glasses were characterized with several techniques, including ellipsometry, UV-vis-NIR absorption spectroscopy, steady-state photoluminescence spectroscopy and time-resolved luminescence. The compositions' effects on optical properties such as refraction indexes, Eu3+ oscillator strengths and luminescence lifetimes were accessed from the analysis of the experimental results. Judd-Ofelt theory was used to analyze all these aspects, which allow the detection of a mismatch of optical properties from absorption and emission spectroscopy. This mismatch was confirmed from the time-resolved data, showing the existence of two different spectroscopic Eu3+ species. From those results it is concluded that there is evidence for lanthanide aggregation, giving rise to self-quenching effects that may be described through resonance energy transfer mechanisms. The difference between luminescence lifetimes for isolated and aggregated Eu(III) is interpreted as due to different interactions with oxygen in the matrix, namely degree of covalency of the Eu-O bond and point group symmetry of the lanthanide.

  3. Effect of Eu, Tb codoping on the luminescent properties of Y2O3 hollow microspheres

    NASA Astrophysics Data System (ADS)

    Jiu, Hongfang; Fu, Yuehua; Zhang, Lixin; Sun, Yixin; Wang, Yuanzhong

    2012-12-01

    Y2O3:Eu3+, Tb3+ hollow microspheres are prepared with different doping concentration of Eu3+ and Tb3+ ions and synthesizing temperatures from 700 to 1000 °C via a urea-based homogeneous precipitation technique with colloidal melamine formaldehyde (MF) microspheres as templates followed by a subsequent calcination process. The resulted hollow microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the calcination temperature. The photoluminescence spectra indicate the Eu3+ and Tb3+ co-doped Y2O3 microspheres show five main emission peaks: three at 591, 609 and 629 nm originate from Eu3+ and two at 482 and 541 nm originate from Tb3+, under excitation of 250-340 nm irradiation. The luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu3+ and Tb3+ ions were induced into the Y2O3 lattice and the energy transfer from Tb3+ to Eu3+ ions in these phosphors was found.

  4. Highly enhanced luminescence of nanocrystalline TiO 2:Eu 3+ phosphors

    NASA Astrophysics Data System (ADS)

    Yi, Soung-soo; Bae, Jong Seong; Moon, Byung Kee; Jeong, Jung Hyun; Kim, Jung Hwan

    2006-05-01

    Narrow-dispersed nanocrystalline TiO 2:Eu 3+ phosphors have been synthesized by reverse micelles and solvothermal synthetic method in toluene solutions. Different concentrations of europium nitrate pentahydrate (5.0, 10.0, 20.0 and 25.0 mol%) were dissolved in water. After the solution was thermally treated at 250 °C for 20 h in an autoclave, low-dispersed TiO 2:Eu 3+ nanocrystalline particles with average size of <5 nm were synthesized. The nanocomposites were composed nominally of TiO 2 shell with Eu 2O 3 core. The crystalline phase and microstructure of the nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Also, luminescent spectra and composition ratio were measured using luminescent spectrometer and energy dispersive X-ray spectrometer. The radiation was dominated by the red emission peak at 616 nm and the highest emission intensity was observed with TiO 2:Eu 0.2, whose brightness was increased by a factor of 1.9 in comparison with that of TiO 2:Eu 0.05. The photoluminescence and excitation spectra show similar behavior as a function of Eu concentration.

  5. Heroism and Science Education Reform.

    ERIC Educational Resources Information Center

    White, Robyn; Wallace, John

    1999-01-01

    Describes the activities of two prominent science educators who presided over Australian science curriculum reforms during the 1960s and 1970s. Represents the educators' actions as heroic and describe how the Heroes shaped, modified, and united the culture through referents, rituals, and artifacts. Speculates on the importance of heroic activity…

  6. Integrated reformer and shift reactor

    SciTech Connect

    Bentley, Jeffrey M.; Clawson, Lawrence G.; Mitchell, William L.; Dorson, Matthew H.

    2006-06-27

    A hydrocarbon fuel reformer for producing diatomic hydrogen gas is disclosed. The reformer includes a first reaction vessel, a shift reactor vessel annularly disposed about the first reaction vessel, including a first shift reactor zone, and a first helical tube disposed within the first shift reactor zone having an inlet end communicating with a water supply source. The water supply source is preferably adapted to supply liquid-phase water to the first helical tube at flow conditions sufficient to ensure discharge of liquid-phase and steam-phase water from an outlet end of the first helical tube. The reformer may further include a first catalyst bed disposed in the first shift reactor zone, having a low-temperature shift catalyst in contact with the first helical tube. The catalyst bed includes a plurality of coil sections disposed in coaxial relation to other coil sections and to the central longitudinal axis of the reformer, each coil section extending between the first and second ends, and each coil section being in direct fluid communication with at least one other coil section.

  7. Steam Reforming of Hydrocarbon Fuels

    SciTech Connect

    Ming, Qimin; Healey, T; Allen, Lloyd; Irving, Patricia M.

    2002-12-01

    has developed a proprietary catalyst formulation for the fuel processor that is being developed for use with polymer electrolyte membrane fuel cells. The catalyst has been tested for the steam reforming of various hydrocarbons such as natural gas, iso-octane, retail gasoline, and hexadecane. A 300h continuous test has shown that the catalyst has very stable performance for steam reforming of iso-octane at 800?C with a steam/C ratio of 3.6. The same catalyst was also tested for steam reforming hexadecane (a surrogate of diesel) for 73h as well as natural gas for over 150h continuously, without deactivation or carbon deposition. Sulfur tolerance of the catalyst was tested using iso-octane containing various concentrations of sulfur. There was no catalyst deactivation after a 220h continuous test using iso-octane with 100ppm sulfur. For comparison, a nickel catalyst (12wt.% Ni/Al2O3) was also tested using different levels of sulfur in iso-octane. The results indicated that the InnovaTek catalyst has a substantially improved sulfur resistance compared to the nickel catalysts currently used for steam reforming. In addition, a variation of the catalyst was also used to reduce CO concentration to < 1% by water gas shift reaction.

  8. Teacher Empowerment and School Reform

    ERIC Educational Resources Information Center

    Thornburg, Devin G.; Mungai, Anne

    2011-01-01

    Teachers in high-needs settings working with diverse populations are typically cited as a central element for school improvement yet are often described as resistant to such efforts. We sought to investigate the reasons behind teachers' views and beliefs about school reform within the context of collaboration and professional development, rather…

  9. Steam Hydrocarbon Cracking and Reforming

    ERIC Educational Resources Information Center

    Golombok, Michael

    2004-01-01

    The interactive methods of steam hydrocarbon reforming and cracking of the oil and chemical industries are scrutinized, with special focus on their resemblance and variations. The two methods are illustrations of equilibrium-controlled and kinetically-controlled processes, the analysis of which involves theories, which overlap and balance each…

  10. Structural Management with Participatory Reforms.

    ERIC Educational Resources Information Center

    Shaw, Judy

    Administrative managers who have the trust of their employees, who listen to their employees openly, and who share power with their employees are better equipped to confront and overcome obstacles. This paper discusses models for structural management that include participatory reforms. It identifies four common models of administration--rational,…

  11. Five Obstacles to Grading Reform

    ERIC Educational Resources Information Center

    Guskey, Thomas R.

    2011-01-01

    Educators seeking to reform grading must combat five long-held traditions that stand as formidable obstacles to change: (1) Grades should provide the basis for differentiating students; (2) grade distributions should resemble a bell-shaped curve; (3) grades should be based on students' standing among classmates; (4) poor grades prompt students to…

  12. Assessing Institutionalization of Educational Reforms

    ERIC Educational Resources Information Center

    Aypay, Ahmet; Kalayci, Serpil Sezer

    2008-01-01

    This study aims to assess the institutionalization of a major reform in the faculties of education in Turkey in the 1990s. A survey was administered to faculty members in eight faculties of education in the academic year 2005-2006. Factor analysis, t-tests and ANOVAs, and OLS regressions were used. Findings indicate that the most problematic area…

  13. Congress enacts health care reform.

    PubMed

    2010-03-01

    Health care reform at last: After nearly a century of effort by Presidents from Theodore Roosevelt on down, the Congress finally agreed on and President Barack Obama signed into law a system that covers most Americans, regulates sharp insurance practices, and embraces a paradigm shift from acute institutionally focused care to chronic disease management based on home and community-based care. PMID:20465039

  14. Education Reform: A Governor's View.

    ERIC Educational Resources Information Center

    Riley, Richard W.

    Enactment of South Carolina's Education Improvement Act of 1984 taught several lessons about successful education reform. The law provides for raising student performance by increasing academic standards; strengthening the teaching and testing of basic skills; elevating the teaching profession; improving leadership, management, and fiscal…

  15. Tax Reform and Higher Education.

    ERIC Educational Resources Information Center

    Franck, Gail

    1987-01-01

    The effect of the Tax Reform Act of 1986 on college and university revenues and expenditures is reviewed. Institutional revenues are derived primarily from five sources: tuition, charitable contributions, debt financing, endowment income, and governmental appropriations. The effect of the new law on family and student income, savings, student…

  16. Poor Children and Welfare Reform.

    ERIC Educational Resources Information Center

    Golden, Olivia

    This book analyzes how welfare reform can improve the lives of children, based on a study of successful programs that provide services to needy children and their families. The study looked at programs that operated in conjunction with the welfare department before the enactment of the Family Support Act and that operated successfully. Chapter 1…

  17. Reforming the Educational Administration Curriculum.

    ERIC Educational Resources Information Center

    Miklos, Erwin

    This paper discusses the conceptual reform of university-based graduate level administrator preparation programs. The functionalist, interpretative, and critical approaches to social science have important implications for the study of motivation, decision-making, communication and leadership. Interpretative and critical approaches must be woven…

  18. Misrecognition and Science Education Reform

    ERIC Educational Resources Information Center

    Brandt, Carol B.

    2012-01-01

    In this forum, I expand upon Teo and Osborne's discussion of teacher agency and curriculum reform. I take up and build upon their analysis to further examine one teacher's frustration in enacting an inquiry-based curriculum and his resulting accommodation of an AP curriculum. In this way I introduce the concept of misrecognition (Bourdieu and…

  19. Teacher Education Reform. Essay Review.

    ERIC Educational Resources Information Center

    Steiner-Khamsi, Gita

    1999-01-01

    Reviews three books that examine teacher-education reform from an international comparative perspective: "The Crisis in Teacher Education: A European Concern," by Anthony Adams and Witold Tulasiewicz; "Global Perspectives on Teacher Education," edited by Colin Brock; and "Learning and Teaching in an International Context: Research, Theory and…

  20. Battling for national health reform.

    PubMed

    DiVenere, L; Davis, M C

    1993-03-01

    At stake are the futures of all health care providers, including those that provide home care and hospice care. Who in Washington holds the ammunition to wage a winning war? Here is your insider's guide to the health reform leaders and their likely strategies. Be assured only that their battles will be intense. PMID:10123976

  1. Reform and Resistance at Oxford

    ERIC Educational Resources Information Center

    Labi, Aisha

    2006-01-01

    In recent years, both Harvard and Oxford Universities have been rattled by reform-minded--some say brash--leaders determined to question the status quo. At Harvard, President Lawrence H. Summers proved too controversial for his own good and is scheduled to step down this month after five contentious years in office. But at Oxford, John Hood, who…

  2. Holmes Group Pursues Reform Agenda.

    ERIC Educational Resources Information Center

    Murray, Frank B.

    1987-01-01

    The Holmes Group is a national organization of some 90 research universities that addresses the low quality of teacher preparation. Its goals are to reform teacher education and teaching itself by promoting intellectually sound programs, recognizing teacher differences, revising standards, connecting education programs with schools, and improving…

  3. Group Polarization and Educational Reform

    ERIC Educational Resources Information Center

    Tanner, David; Magdaleno, Kenneth

    2008-01-01

    Although educational leaders may be optimistic about initiating change, lasting reforms are rare. The group polarization literature, although dated, provides an important explanation for a very current problem. The theory holds that when there are differences of opinion to begin with, a counter-conformity effect works among members of groups.…

  4. Cultural Narcissism and Education Reform

    ERIC Educational Resources Information Center

    Pajak, Edward F.

    2011-01-01

    Background/Context: Scholars have described American culture in recent decades as narcissistic, manifested by displays of self-absorption tantamount to a pathological syndrome that has reached epidemic proportions. An education reform movement that is highly critical of public schools, teachers, and students has simultaneously emerged, espousing a…

  5. Reforming Educational Administration: Ethical Considerations.

    ERIC Educational Resources Information Center

    Calabrese, Raymond L.

    1993-01-01

    Suggests that serious ethical questions regarding the preparation of prospective school administrators have arisen out of the American reform movement. Discusses university-sponsored educational administration programs in the context of the social contract between the university and its various shareholders. Argues that such programs have a major…

  6. Overview of the Greek legislation regarding assisted reproduction and comparison with the EU legal framework.

    PubMed

    Leon, Grigorios; Papetta, Angela; Spiliopoulou, Chara

    2011-12-01

    The aim of this research was to ascertain how the opportunities now open by the Greek legislation regarding assisted reproduction fits with Greek society and how it compares with the wider EU legal framework. A revision of the Greek legislation took place a few years ago, with two new Acts. The different issues that arise from the two Acts and the relevant statements are examined. Issues such as the legal state of the newborn, involvement of a third party in the reproduction process, surrogacy, post-mortem fertilization and cryopreserved embryos are analytically presented. A pragmatic orientation seems to unfold, which is characterized by the prevalence of the benefits that can be obtained from the resources of reproductive technologies. The reality is that Greek society is still quite traditional, therefore specific parts of this new legislation do not fit with the current picture. A comparison with the other national legislative systems in existence within the EU has revealed specific differences. The creation of a common legislative framework covering most of the points raised through the implementation of assisted reproduction could provide guidance for any future legislative reforms or updates within a EU state, including Greece. PMID:22030280

  7. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    DOE PAGESBeta

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squaredmore » Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  8. From the Ternary Eu(Au/In)2 and EuAu4(Au/In)2 with Remarkable Au/In Distributions to a New Structure Type: The Gold-Rich Eu5Au16(Au/In)6 Structure.

    PubMed

    Steinberg, Simon; Card, Nathan; Mudring, Anja-Verena

    2015-09-01

    The ternary Eu(Au/In)2 (EuAu(0.46)In(1.54(2))) (I), EuAu4(Au/In)2 (EuAu(4+x)In(2-x) with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2-"EuAu4In2". The site preferences of the disordered Au/In positions in II were investigated for different hypothetical "EuAu4(Au/In)2" models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au-In contacts. A chemical bonding analysis on two "EuAu5In" and "EuAu4In2" models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems. PMID:26270622

  9. Tri-reforming and combined reforming of methane for producing syngas with desired hydrogen/carbon monoxide ratios

    NASA Astrophysics Data System (ADS)

    Pan, Wei

    This dissertation is an exploratory study of a new process concept for direct production of synthesis gas (CO + H2) with desired H 2/CO ratios (1.5--2.0) for methanol synthesis and F-T synthesis, using CO2 together with steam and unconverted O2 in flue gas from fossil fuel-fired electric power plants to react with methane or natural gas. This new process is called tri-reforming, referring to simultaneous CO2-steam-O2 reforming of methane or natural gas. This study included (1) The investigation of carbon formation in the tri-reforming process. For comparison, carbon formation in the combined reforming and CO2 reforming reaction was studied as well. (2) The effect of reaction conditions and feed compositions on equilibrium composition (e.g. H2/CO ratio) and equilibrium conversions in the tri-reforming process. (3) The role of catalysts in the tri-reforming process, especially the effect of catalysts on CO2 conversion in the presence of H 2O and O2. It was clearly evidenced from this study that CO in the product stream is probably the major source of carbon over Ni/Al2O3 in the equimolar CO2-CH4 reforming at 650°C and 1 atm. Addition of either O2 or H2O into the CO 2 reforming reaction system can suppress carbon formation. It was demonstrated that carbon-free operation can be achieved in the tri-reforming process. A thermodynamic comparison of tri-reforming with feed compositions of (H2O+CO2+0.5O2)/CH4 (mol ratio) = 1 showed that O2 improves equilibrium CH4 conversion, yet greatly decreases equilibrium CO2 conversion. H2O in tri-reforming has a significant effect on the H2/CO ratio in the products, while O2 has a minor effect. A kinetic study and catalytic performance tests indicated that the support in a supported catalyst has a significant role in enhancing CO2 conversion to CO in the presence of H2O and O2 in tri-reforming. The Ni/MgO catalyst showed superior performance with close to equilibrium CH4 and CO2 conversions at 850°C, 1 atm, and 32,000 ml

  10. 5d-4f emission of Eu2+ and electron-vibrational interaction in several alkaline earth sulfides doped with Eu2+ and Er3+

    NASA Astrophysics Data System (ADS)

    Kumar, G. A.; Liu, D.-X.; Tian, Y.; Brik, M. G.; Sardar, D. K.

    2015-12-01

    Several alkaline earth sulfides doped with Eu2+ and Er3+ ions have been synthesized and shown to be potential phosphors for applications in the visible spectral range. The excitation and emission spectra corresponding to the 4f-5d interconfigurational transitions of Eu2+ were analyzed with an aim of extraction of the main parameters of the electron-vibrational interaction. The values of the Huang-Rhys factor, effective phonon energies, and zero-phonon line positions were systematically compared for all studied materials; physical trends were discussed. As a test for the validity of the obtained parameters, the Eu2+ 5d-4f emission bands were modeled to yield good agreement with the experimental spectra.

  11. Polyethylene recycling: Waste policy scenario analysis for the EU-27.

    PubMed

    Andreoni, Valeria; Saveyn, Hans G M; Eder, Peter

    2015-08-01

    This paper quantifies the main impacts that the adoption of the best recycling practices together with a reduction in the consumption of single-use plastic bags and the adoption of a kerbside collection system could have on the 27 Member States of the EU. The main consequences in terms of employment, waste management costs, emissions and energy use have been quantified for two scenarios of polyethylene (PE) waste production and recycling. That is to say, a "business as usual scenario", where the 2012 performances of PE waste production and recycling are extrapolated to 2020, is compared to a "best practice scenario", where the best available recycling practices are modelled together with the possible adoption of the amended Packaging and Packaging Waste Directive related to the consumption of single-use plastic bags and the implementation of a kerbside collection system. The main results show that socio-economic and environmental benefits can be generated across the EU by the implementation of the best practice scenario. In particular, estimations show a possible reduction of 4.4 million tonnes of non-recycled PE waste, together with a reduction of around €90 million in waste management costs in 2020 for the best practice scenario versus the business as usual scenario. An additional 35,622 jobs are also expected to be created. In environmental terms, the quantity of CO2 equivalent emissions could be reduced by around 1.46 million tonnes and the net energy requirements are expected to increase by 16.5 million GJ as a consequence of the reduction in the energy produced from waste. The main analysis provided in this paper, together with the data and the model presented, can be useful to identify the possible costs and benefits that the implementation of PE waste policies and Directives could generate for the EU. PMID:25976302

  12. Solar Reforming of Carbon Dioxide to Produce Diesel Fuel

    SciTech Connect

    Dennis Schuetzle; Robert Schuetzle

    2010-12-31

    This project focused on the demonstration of an innovative technology, referred to as the Sunexus CO2 Solar Reformer, which utilizes waste CO2 as a feedstock for the efficient and economical production of synthetic diesel fuel using solar thermal energy as the primary energy input. The Sunexus technology employs a two stage process for the conversion of CO2 to diesel fuel. A solar reforming system, including a specially designed reactor and proprietary CO2 reforming catalyst, was developed and used to convert captured CO2 rich gas streams into syngas (primarily hydrogen and carbon monoxide) using concentrated solar energy at high conversion efficiencies. The second stage of the system (which has been demonstrated under other funding) involves the direct conversion of the syngas into synthetic diesel fuel using a proprietary catalyst (Terra) previously developed and validated by Pacific Renewable Fuels and Chemicals (PRFC). The overall system energy efficiency for conversion of CO2 to diesel fuel is 74%, due to the use of solar energy. The results herein describe modeling, design, construction, and testing of the Sunexus CO2 Solar Reformer. Extensive parametric testing of the solar reformer and candidate catalysts was conducted and chemical kinetic models were developed. Laboratory testing of the Solar Reformer was successfully completed using various gas mixtures, temperatures, and gas flow rates/space velocities to establish performance metrics which can be employed for the design of commercial plants. A variety of laboratory tests were conducted including dry reforming (CO2 and CH{sub 4}), combination dry/steam reforming (CO2, CH{sub 4} & H{sub 2}O), and tri-reforming (CO2, CH{sub 4}, H{sub 2}O & O{sub 2}). CH{sub 4} and CO2 conversions averaged 95-100% and 50-90% per reformer cycle, respectively, depending upon the temperatures and gas space velocities. No formation of carbon deposits (coking) on the catalyst was observed in any of these tests. A 16 ft. diameter

  13. Luminescence properties of a novel green emitting Ba2CaZn2Si6O17:Eu2+ phosphor for white light - Emitting diodes applications

    NASA Astrophysics Data System (ADS)

    Annadurai, G.; Kennedy, S. Masilla Moses; Sivakumar, V.

    2016-05-01

    A novel green emitting Ba2CaZn2Si6O17:Eu2+ (BCZSO:Eu2+) phosphor was synthesized using conventional high temperature solid state reaction method. Powder X-ray diffraction was carried out to confirm the phase formation of the synthesized phosphors. Photoluminescence emission spectrum was recorded under excitation at 340 nm. The BCZSO:Eu2+ phosphor exhibited an intense asymmetric green emission band around 502 nm which originated from the 4f65d1 → 4f7 transition of Eu2+ ion. The optimum doping concentration of Eu2+ was found to be 0.06 mol. The energy transfer mechanism among Eu2+ in BCZSO phosphor was found to be a dipole-dipole interaction, and the critical distance (RC) for the Eu2+ ions calculated by the concentration quenching and spectral overlap methods were 23.2 Å and 13.7 Å, respectively. The decay curve of BCZSO:Eu2+ phosphors were discussed. The CIE chromaticity coordinate values (x = 0.259, y = 0.463) of BCZSO:Eu2+ phosphor were located in green region and the correlated color temperature was 7571 K. All these properties gave an indication that BCZSO:Eu2+ phosphor could be a potential green-emitting phosphor for UV based white light emitting diodes.

  14. Synthesis of high-silica EU-1 zeolite in the presence of hexamethonium ions: a seeded approach for inhibiting ZSM-48.

    PubMed

    Xu, Qinghu; Gong, Yanjun; Xu, Wenjing; Xu, Jun; Deng, Feng; Dou, Tao

    2011-06-01

    A seeded approach was developed to synthesize high-silica EU-1 zeolite via inhibiting the co-crystallization of ZSM-48 in the presence of hexamethonium (HM) ions. A systematic study was carried out to determine factors such as seed content and SiO(2)/Al(2)O(3) ratio, which influenced the crystallization of high-silica EU-1 and transformation of EU-1 into ZSM-48. Using EU-1 seeds, not only well-crystallized pure EU-1 zeolites with SiO(2)/Al(2)O(3) ratios more than 500 were synthesized, but also the co-crystalline of ZSM-48/EU-1 or pure ZSM-48 was obtained in control from silica-rich mixture gels. Furthermore, the kinetic features of the seeded synthesis of EU-1 zeolites with SiO(2)/Al(2)O(3) ratios of 55, 190, and 500 were examined. It was found that seeds played crucial roles in the decrease of apparent activation energy of EU-1 nucleation and inhibiting the transformation of EU-1 into ZSM-48. The HM and Al species performed synergistic roles to inhibit the formation ZSM-48 during high-silica EU-1 nucleation and crystal growth. PMID:21444090

  15. The preparation of a Eu3+-doped ZnO bi-functional layer and its application in organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Wu, Na; Luo, Qun; Qiao, Xvsheng; Ma, Chang-Qi

    2015-12-01

    Recently, spectra conversion has been used to minimize energy loss in photovoltaic devices. In this work, we explore the development of a novel Eu3+-doped ZnO bi-functional layer for use in organic solar cells. The bi-functional layer acts as both a spectra conversion and an electron transporting layer. Compared to conventional spectra conversion layers, it has a simpler device structure, is easier to fabricate, and has a wider spectrum-sensitized region. A series of Eu3+-doped ZnO nanocrystals were synthesized using the simple solution route. X-ray powder diffraction patterns (XRD), transmission electron microscopy (TEM), and UV-visible absorbance spectra were used to characterize the obtained ZnO nanocrystals. The results reveal that the size and bandgap of ZnO nanocrystals can be controlled through regulation of the doping concentration of Eu3+ ions. The energy transfer of ZnO → Eu3+ is observed by photoluminescence (PL) spectra. At a bandgap excitation of around 300-400 nm, a typical emission band from the Eu3+ is obtained. By employing the Eu3+- doped ZnO nanocrystals as a buffer layer in a P3HT:PC61BM bulk heterojunction device, the obtained performance is similar to the undoped ZnO device, indicating that the electrical properties of ZnO are not affected by Eu3+ doping. Due to the down-conversion energy transfer between ZnO and Eu3+, the external quantum efficiency of the ZnO:Eu3+ device at 300-400 nm is higher than that of the pure ZnO device, which subsequently leads to an increase in short circuit current density (J SC). This work proves that it is possible to improve the solar spectrum response in the ultraviolet region of organic solar cells effectively by incorporating the bi-functional layer.

  16. Perceived Distributive Fairness of EU Transfer Payments, Outcome Favorability, Identity, and EU-Tax Compliance.

    PubMed

    Hartner, Martina; Rechberger, Silvia; Kirchler, Erich; Wenzel, Michael

    2011-01-01

    In a representative UK study (N = 1000) the link between distributive fairness perceptions, outcome favorability, identity, and tax compliance was researched in the context of European transfer payments. Results showed that both forms of tax compliance (i.e., individual and collective EU-tax compliance) were influenced by perceived distributive fairness judgments of EU transfer payments. Fairness itself was related to perceived outcome favorability (i.e., whether their own nation benefits from the EU in financial as well as socio-political terms). Additionally, national identifiers (i.e., people identifying with their own nation, but not with Europe) perceived EU membership as unbeneficial in financial as well as in socio-political terms and thus considered the transfer payments as less fair. Dual identifiers (i.e., people identifying with their own nation and with Europe) perceived the socio-political outcomes from EU membership as more beneficial and thus evaluated the transfer payments as fairer. PMID:21412442

  17. Do supranational EU institutions make a difference? EU asylum law before and after ‘communitarization’

    PubMed Central

    Ripoll Servent, Ariadna; Trauner, Florian

    2014-01-01

    ABSTRACT This article examines whether the empowerment of the European Union's (EU) supranational institutions has had an impact on the development of EU asylum. By systematically investigating EU asylum law before and after ‘communitarization’, it argues that its ‘policy core’ has maintained a high degree of continuity. An advocacy coalition under the leadership of the interior ministers managed to co-opt pivotal actors in the newly empowered European Commission and European Parliament. By contenting themselves with changes of secondary order, these EU institutions accepted and institutionalized the restrictive and weakly integrated core of EU asylum set by the Council in the first negotiation round. Their role and decisions were driven not only by the negotiation dynamics and political expediency, but also by new inter- and intra-institutional norms fostering consensual practices. PMID:26924934

  18. Photo-induced charge state conversion of Eu2+ in Ca2ZnSi2O7

    NASA Astrophysics Data System (ADS)

    Kamioka, Hayato; Hirano, Masahiro; Hosono, Hideo

    2009-09-01

    Eu2+ doped sorosilicate Ca2ZnSi2O7 (melilite) exhibits a broad band emission peaking at ˜600 nm (˜2 eV) due to the electric dipole allowed transition of 4f65d1 to 4f7 of Eu2+ by an excitation with blue light (460 nm). Strong O2- ligand field with low symmetry due to the layered tetragonal crystallographic structure of the melilite may play a dominant role in lowering the emission band energy to ˜2 eV. In addition, line emissions attributable to the transitions from D50 to F7J of Eu3+ ions are detected by an excitation with deep UV light with sub-360 nm wavelengths. This is due to the formation of transient Eu3+ ions via charge transfer from Eu2+ to the matrix. The lifetime of the transient Eu3+ ion is found to be 58 ms by a pump-probe measurement, in which UV pulse laser and green continuous wave laser are employed as pump and probe lights, respectively. Based on these results, the energy diagram of Eu2+ in Ca2ZnSi2O7 is proposed.

  19. Synthesis and luminescent properties of ternary complex Eu(UVA)3Phen in nano-TiO2

    NASA Astrophysics Data System (ADS)

    Lü, Yu-guang; Gong, Zhong-ping; Gao, Hong-bing; Zhou, Shu-jing; Lü, Kui-lin; Wang, Ying; A, Du; Du, Hao-ran; Zhang, Li; Zhang, Fu-jun

    2015-01-01

    By introducing 2-hydroxy-4-methoxy-benzophenone (UVA) and 1,10-phenanthroline (Phen) as the ligands, the ternary rare earth complex of Eu(UVA)3Phen is synthesized, and it is characterized by elemental analysis, mass spectra (MS) and infrared (IR) and ultraviolet (UV) spectroscopy. Results show that the Eu(III) in complex emits strong red luminescence when it is excited by UV light, and it has higher sensitized luminescent efficiency and longer lifetime. The organic-inorganic thin film of complex Eu(UVA)3Phen doped with nano-TiO2 is prepared, and the nano-TiO2 is used in the luminescence layer to change the luminescence property of Eu(UVA)3Phen. It is found that there is an efficient energy transfer process between ligands and metal ions. Moreover, in an indium tin oxide (ITO)/poly(N-vinylcar-bazole) (PVK)/Eu(UVA)3Phen/Al device, Eu3+ can be excited by intramolecular ligand-to-metal energy transfer process. The main peak of emission at 613 nm is attributed to 5D0→7F2 transition of the Eu3+, and this process results in the enhanced red emission.

  20. Use of additives in the electrodeposition of nanostructured Eu3+/ZnO films for photoluminescent devices.

    PubMed

    Li, Gao-Ren; Dawa, Ci-Ren; Lu, Xi-Hong; Yu, Xiao-Lan; Tong, Ye-Xiang

    2009-02-17

    Rare-earth ion-doped ZnO has been the focus of numerous investigations because of its unique optical properties and promising applications in optoelectronic devices. Here we presented a facile electrochemical deposition route for the controllable preparation of Eu3+/ZnO nanostructures on a large scale. The prepared Eu3+/ZnO deposits were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, selected area electron diffraction, and X-ray photoelectron spectroscopy. Herein, the growth mechanisms of Eu3+/ZnO nanosheets and nanorods were discussed. The formation process of Eu3+/ZnO foam-like nanostructures is illuminated in this paper. The room temperature photoluminescence properties of the Eu3+/ZnO foam-like nanostructures were investigated. The sharp 4f-4f transition emissions of Eu3+ can be directly observed at 593, 617, and 698 nm. An energy transfer between ZnO and Eu3+ is shown to occur under UV excitation. PMID:19199740

  1. Laser site-selective spectroscopy of Eu3+ ions doped Y4Al2O9

    NASA Astrophysics Data System (ADS)

    Kaczkan, M.; Turczyński, S.; Pawlak, D. A.; Wencka, M.; Malinowski, M.

    2016-08-01

    Eu3+ doped Y4Al2O9 (YAM) crystals were prepared by the micro-pulling down method. Optical-absorption and laser-selective-excitation techniques along with the luminescence decays have been used to reveal that Eu3+ ions in YAM occupy three distinct sites, which were characterized and discussed. The Stark energy levels of Eu3+ at three different sites in YAM were assigned from selectively excited emission spectra at 10 K. The intensity ratio of forced electric dipole (5D0 → 7F2) and magnetic dipole (5D0 → 7F1) transitions was discussed in order to obtain information about the degree of asymmetry of the luminescent centers. These results were confirmed by the luminescence lifetime measurements. The temperature dependent photo-luminescence spectra indicated that there is no energy transfer between different sites in the 10-300 K range.

  2. Electricity market reforms: Institutional developments, investment dynamics and game modeling

    NASA Astrophysics Data System (ADS)

    Pineau, Pierre-Olivier

    The reform trend of the 1990's in electricity markets recreates, to some extent, the institutional framework from which they developed one century ago. Although these reforms do not endeavor to completely remove regulation, the basic objectives of deregulation dwell on limiting central and governmental control over the industry in order to promote free competition at all possible levels. To assess whether the electricity industry is or is not moving back to a 19th century structure is not the goal of this thesis. We will rather try to understand on what grounds deregulation reforms stand and review how different countries and large utilities have reacted to this trend. The special nature of electricity (non-storable basic good, centrally produced) creates different obstacles in the restructuring of electricity markets, compared to other industries like the airline or telecommunication ones. For example, the dominant positions of some utilities, the production structure and the importance of electricity in modern life could transform these reforms in a threatening move for consumers. Another specific issue arising from deregulation, now that national energy policy goals no longer rule the behavior of utilities, is how investment will be coordinated in the new market. A key element to keep in sight is the competition level targeted by these reforms. To which extent full competition can really occur in electricity markets remains an unanswered question. Indeed, the oligopolistic structure of the market could prevent such an outcome. An investigation of the investment dynamics in such a context seems therefore appropriate, and this will be an important theme of the thesis. This work offers an analysis of deregulated electricity markets and studies the oligopolistic market dynamics that could prevail in the new structure. Two complementary approaches are used for these purposes. The first is institutional and presents a thorough illustration of the economic arguments

  3. Synthesis and Photoluminescent Properties of Nanorod Bundle Ln4O(OH)9NO3:Eu(Ln = Y, Lu) Prepared by Hydrothermal Method.

    PubMed

    Li, Ling; Noh, Hyeon Mi; Liu, Xiaoguang; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun

    2015-07-01

    Well-crystallized nanorod bundles Ln4O(OH)9NO3:1%Eu(Ln = Y, Lu) have been successfully prepared by hydrothermal method. The crystalline phase, size and optical properties were characterized using powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), infrared (IR) spectrograph and photoluminescent (PL) spectra. Site occupations of Eu3+ in crystals Ln4O(OH)9NO3:Eu(Ln = Y, Lu) were discussed based on excitation spectra and the empirical relationship formula between the charge transfer (CT) energy and the environmental factor. The emission spectra exhibited that the strongest emission peaks with an excitation wavelength of 395 nm were at 617 and 626 nm in crystal Lu4O(OH)9NO3:1%Eu and Y4O(OH)9NO3:1%Eu, respectively, both of which come from 5D0-7F2 transition of the Eu3+ ions. The broad excitation peaks at about 254 and 255 nm were found when monitored at 617 and 628 nm in crystal Lu4O(OH)9NO3:1%Eu and Y4O(OH)9NO3:1%Eu, respectively, which were due to O-Eu CT transition. Based on the dielectric theory of complex crystal, the CT bands at about 254 and 255 nm in Ln4O(OH)9NO3:1%Eu(Ln = Y, Lu) were assigned to the transition of O-Eu at Ln3(Ln = Y, Lu) site, from which we can conclude that Eu3+ ions occupied the site of Ln3(Ln = Y, Lu) in crystal Ln4O(OH)9NO3:1%Eu(Ln = Y, Lu). It put forward a new route to investigate site occupation of luminescent center ions in rare earth doped complex inorganic luminescence materials. PMID:26373076

  4. Spectroscopic study on the role of TiO{sub 2} in the adsorption of Eu(III) and U(VI) on silica surfaces in aqueous solutions

    SciTech Connect

    Im, Hee-Jung Park, Kyoung Kyun; Jung, Euo Chang

    2014-10-15

    Highlights: • Enhanced adsorption of Eu(III) and U(VI) onto TiO{sub 2}-coated silica. • Enhanced Eu(III) luminescence and lifetime on TiO{sub 2}-coated silica. • Energy transfer from TiO{sub 2} of TiO{sub 2}-coated silica to Eu(III) in solutions. - Abstract: To determine the effects of TiO{sub 2} on the adsorption of actinides onto mineral surfaces in groundwater, silica was partially coated with TiO{sub 2}, and Eu(III) and U(VI) were individually adsorbed from separate 0.1 mM concentration solutions. The TiO{sub 2}-coated silica showed higher Eu(III) and U(VI) adsorption capacities for increasing amounts of TiO{sub 2} coated on the silica surfaces, and thus the existence of TiO{sub 2} can decrease the mobility of Eu(III) and U(VI) contaminants. In luminescence studies, it was found that TiO{sub 2} considerably enhanced the luminescence of the adsorbed Eu(III) indicating that TiO{sub 2}–Eu(III) forms surface complexes which may decrease the number of water molecules at the inner sphere of Eu(III), but this was not observed for U(VI). An energy transfer from the TiO{sub 2} to the Eu(III) was confirmed in this case of amorphous TiO{sub 2}-coated silica in Eu(III) solutions, and an increase of the luminescence lifetime of Eu(III) for increasing concentrations of coated TiO{sub 2} was also observed.

  5. Enhanced luminescence of Tb{sup 3+}/Eu{sup 3+} doped tellurium oxide glass containing silver nanostructures

    SciTech Connect

    Kassab, Luciana R. P.; Araujo, Cid B. de

    2009-05-15

    We report on energy transfer studies in terbium (Tb{sup 3+})--europium (Eu{sup 3+}) doped TeO{sub 2}-ZnO-Na{sub 2}O-PbO glass containing silver nanostructures. The samples excitation was made using ultraviolet radiation at 355 nm. Luminescence spectra were recorded from approx =480 to approx =700 nm. Enhanced Eu{sup 3+} luminescence at approx =590 nm (transition {sup 5}D{sub 0}-{sup 7}F{sub 1}) and approx =614 nm (transition {sup 5}D{sub 0}-{sup 7}F{sub 2}) are observed. The large luminescence enhancement was obtained due to the simultaneous contribution of the Tb{sup 3+}-Eu{sup 3+} energy transfer and the contribution of the intensified local field on the Eu{sup 3+} ions located near silver nanostructures.

  6. Institutional obstacles to educational reform.

    PubMed

    Bulger, R J

    1994-01-01

    For the full implications of health care reform to be implemented in health professions education, there will need to be a radical rethinking of educational missions and goals, as well as a careful analysis of the obstacles to educational reform that are currently extant within our academic centers and health professions schools. A series of steps should be taken to encourage the development of a collegial spirit among faculty and students across the major health professions. As costs of education become distinct from those of service and research, certain organizational steps will become apparent, such as: 1) developing separate postgraduate and undergraduate medical schools; and 2) forming a regional educational network to respond to the workforce demands of the region. PMID:7960089

  7. Plasma-catalyzed fuel reformer

    DOEpatents

    Hartvigsen, Joseph J.; Elangovan, S.; Czernichowski, Piotr; Hollist, Michele

    2013-06-11

    A reformer is disclosed that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding method and system are also disclosed and claimed herein.

  8. Solar central receiver reformer system for ammonia plants

    NASA Astrophysics Data System (ADS)

    1980-07-01

    Details of the conceptual design, economic analysis, and development plan for a solar central receiver system for retrofitting the Valley Nitrogen Producers, Inc., El Centro, California 600 ST/SD Ammonia Plant are presented. The retrofit system consists of a solar central receiver reformer (SCRR) operating in parallel with the existing fossil fired reformer. Steam and hydrocarbon react in the catalyst filled tubes of the inner cavity receiver to form a hydrogen rich mixture which is the syngas feed for the ammonia production. The SCRR system displaces natural gas presently used in the fossil reformer combustion chamber. The solar reformer retrofit system characteristics and its interface with the existing plant are simple, incorporating state of the art components with proven technology. A northfield composed of one thousand forty second generation heliostats provides solar energy to the receiver which is positioned on top of a 90 meter high steel tower. The overall economics of this system can provide over 20% discount cash flow rate of return with proper investment and market conditions.

  9. Effects of Eu concentration control on crystal growth and scintillation properties for Eu:LiSrAlF6 crystals

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Yokota, Y.; Yamaji, A.; Kurosawa, S.; Kamada, K.; Yoshikawa, A.

    2014-10-01

    Eu doped LiSrAlF6 (Eu:LiSAF) crystals with various Eu concentrations were grown by a micro-pulling-down (μ-PD) method and the effects of Eu concentration control on crystal growth and scintillation properties for Eu:LiSAF crystals were investigated as a neutron scintillator. As-grown Eu0.3%:LiSAF crystal had no visible inclusion while milky parts were observed in the crystals with higher Eu contents. The secondary phases with the chemical composition of EuF2 or EuF3 in the Eu:LiSAF matrix were observed for the crystals with high Eu contents while the secondary phase couldn’t be observed in the powder XRD patterns. In the radioluminescence spectra of Eu:LiSAF crystals under α-ray irradiation, emission peaks around 375 nm originated from 5d-4f transition of Eu2+ ion were observed. The light yields systematically increased with an increase of actual Eu contents in the crystals and the decay times were 1490-1620 ns.

  10. PBS reform - a missed opportunity?

    PubMed

    de Boer, Rebecca

    2009-05-01

    The Pharmaceutical Benefits Scheme (PBS) reform package was announced in 2006 and was designed to save the government significant expenditure on the PBS through mandatory price cuts and price disclosure arrangements for multi-brand products. Perhaps most significantly, the formulary was spilt in two with no linkages between the formularies on either price or therapeutic outcome. This article examines the potential impact of these changes on the PBS and pharmaceutical policy in Australia more broadly. PMID:19563306

  11. Dealing with Resistance to Reform

    NASA Astrophysics Data System (ADS)

    Reif, Marc

    2008-09-01

    About the author: Any teacher, new or experienced, will at times face criticism, resistance, and even hostility from students, parents, and colleagues. An inexperienced teacher who runs a reformed classroom based on classroom discourse and "interactive engagement," both of which may run counter to school culture, risks resistance or even outright revolt. In this essay, which grew out of discussions on the Modeling Instruction Program Listserv, Marc Reif shares some strategies that can be used to forestall or deal with classroom opposition.

  12. Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

    PubMed Central

    Han, Zhaohui; Driewer, Joseph P.; Zheng, Yuanshui; Low, Daniel A.; Li, H. Harold

    2009-01-01

    This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.15:Eu2+ material that is used for computed radiography (CR) but features a significantly smaller effective atomic number—18 versus 49—making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl:Eu2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. The findings were (1) KCl:Eu2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. (2) KCl:Eu2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. (3) After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1%∕h after 12 h. (4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy∕min. (5) The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. (6) Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters (0.3 mm thick lead foils) during irradiation, the over-response was reduced. The authors have demonstrated that KCl:Eu2+ dosimeters have many desirable

  13. Increased Eu²⁺ content and codoping Mn²⁺ induced tunable full-color emitting phosphor Ba(1.55)Ca(0.45)SiO₄:Eu²⁺,Mn²⁺.

    PubMed

    Miao, Shihai; Xia, Zhiguo; Zhang, Jie; Liu, Quanlin

    2014-10-01

    We demonstrated that a new intermediate composition of Ba(1.55)Ca(0.45)SiO4 between the orthosilicates Ca2SiO4 and Ba2SiO4 yields the best phosphor hosts, and interesting luminescence properties can be found from the Eu(2+) singly doped and/or Eu(2+)/Mn(2+) codoped Ba(1.55)Ca(0.45)SiO4 phosphors. The phosphors can be excited by near-ultraviolet (nUV) light at wavelengths ranging from 200 to 450 nm matching well with the nUV light-emitting diode (LED) chips. As a result of fine-tuning the activators of different Eu(2+) content and Eu(2+)/Mn(2+) couples with different ratios, tunable full-color emission under UV light excitation can be realized by combining the blue emission (460 nm) and green emission (520 nm) originating from Eu(2+) with the red emission (595 nm) from Mn(2+) in the Ba(1.55)Ca(0.45)SiO4 host lattice. Energy-transfer efficiency between Eu(2+) and Mn(2+) increases and tunable emission can be obtained with increasing Mn(2+) doping content. These results indicate that the Ba(1.55)Ca(0.45)SiO4:Eu(2+),Mn(2+) phosphor will have potential use in nUV chip pumped white LED devices. PMID:25254295

  14. Eu Anomalies Constrain Recycling of Lower Continental Crust

    NASA Astrophysics Data System (ADS)

    Tang, M.; Rudnick, R. L.; McDonough, W. F.; Gaschnig, R. M.; Huang, Y.

    2014-12-01

    Europium is fractionated from Sm and Gd during intra-crustal differentiation since Eu (II) strongly partitions into feldspar. Statistical analysis of Sm-Eu-Gd concentrations in over 2000 samples from the continental crust reveal that the bulk continental crust has a negative Eu anomaly. Samples include (1) shales, loess, and tillites which represent upper continental crust (n = 415); (2) amphibolite facies rocks, which represent the middle continental crust (n = 1325) and (3) granulite facies rocks (n = 845), which represent the lower continental crust. The upper and middle continental crust have a significant negative Eu anomaly, while the lower continental crust has a significant positive Eu anomaly. The Eu deficit in the upper and middle continental crust, however, cannot be compensated by the Eu excess in the lower continental crust, leaving the bulk continental crust with a negative Eu anomaly (Eu/Eu* = 0.81 ± 0.04, 95% conf.). Since the building blocks of the continental crust (mantle-derived basalts or tonalitic slab melts) do not possess a negative Eu anomaly, removal of lower continental crust, which is the only crustal reservoir enriched in Eu, is required during crustal evolution. A mass balance model of the continents, based on Sm-Eu-Gd systematics, indicates that at least 2.2-3.0 crustal masses may have been added back to the mantle over Earth history via lower crustal recycling.

  15. Reforming Science and Mathematics Education

    NASA Astrophysics Data System (ADS)

    Lagowski, J. J.

    1995-09-01

    Since 1991, the National Science Foundation has signed cooperative agreements with 26 states to undertake ambitious and comprehensive initiatives to reform science, mathematics, and technology education. Collectively, those agreements are known as the State Systemic Initiatives (SSI's). Two complimentary programs, The Urban and Rural Systemic Initiatives (USI's and RSI's), address similar reforms in the nation's largest cities and poorest rural areas. The SSI Program departs significantly from past NSF practice in several ways. The funding is for a longer term and is larger in amount, and the NSF is taking a more activist role, seeking to leverage state and private funds and promote the coordination of programs within states. The Initiatives also have a stronger policy orientation than previous NSF programs have had. The NSF strategy is a reflection of the growing and widely held view that meaningful reforms in schools are most likely to be achieved through state initiatives that set clear and ambitious learning goals and standards; align all of the available policy levers in support of reform; stimulate school-level initiatives; and mobilize human and financial resources to support these changes. Two premises underlie systemic reform: (1) all children can meet significantly higher standards if they are asked to do so and given adequate opportunities to master the content, and (2) state and local policy changes can create opportunities by giving schools strong and consistent signals about the changes in practice and performance that are expected. Because this is an enormous investment of Federal resources that is intended to bring about deep, systemic improvement in the nation's ability to teach science and mathematics effectively, the NSF has contracted with a consortium of independent evaluators to conduct a review of the program. The first of the SSI's were funded in 1991, sufficiently long ago to begin to formulate some initial impressions of their impact. Take

  16. Thermo and photoluminescence properties of Eu3+ activated hexagonal, monoclinic and cubic gadolinium oxide nanorods

    NASA Astrophysics Data System (ADS)

    Dhananjaya, N.; Nagabhushana, H.; Nagabhushana, B. M.; Rudraswamy, B.; Shivakumara, C.; Ramesh, K. P.; Chakradhar, R. P. S.

    2011-04-01

    Different phases of Eu3+ activated gadolinium oxide (Gd (OH)3, GdOOH and Gd2O3) nanorods have been prepared by the hydrothermal method with and without cityl trimethyl ammonium bromide (CTAB) surfactant. Cubic Gd2O3:Eu (8 mol%) red phosphor has been prepared by the dehydration of corresponding hydroxide Gd(OH)3:Eu after calcinations at 350 and 600 °C for 3 h, respectively. When Eu3+ ions were introduced into Gd(OH)3, lattice sites which replace the original Gd3+ ions, a strong red emission centered at 613 nm has been observed upon UV illumination, due to the intrinsic Eu3+ transition between 5D0 and 7F configurations. Thermoluminescence glow curves of Gd (OH)3: Eu and Gd2O3:Eu phosphors have been recorded by irradiating with gamma source (60CO) in the dose range 10-60 Gy at a heating rate of 6.7 °C sec-1. Well resolved glow peaks in the range 42-45, 67-76, 95-103 and 102-125 °C were observed. When γ-irradiation dose increased to 40 Gy, the glow peaks were reduced and with increase in γ-dose (50 and 60 Gy) results the shift in first two glow peak temperatures at about 20 °C and a new shouldered peak at 86 °C was observed. It is observed that there is a shift in glow peak temperatures and variation in intensity, which is mainly attributed to different phases of gadolinium oxide. The trapping parameters namely activation energy (E), order of kinetics (b) and frequency factor were calculated using peak shape and the results are discussed.

  17. Evaluation of Large Volume SrI2(Eu) Scintillator Detectors

    SciTech Connect

    Sturm, B W; Cherepy, N J; Drury, O B; Thelin, P A; Fisher, S E; Magyar, A F; Payne, S A; Burger, A; Boatner, L A; Ramey, J O; Shah, K S; Hawrami, R

    2010-11-18

    There is an ever increasing demand for gamma-ray detectors which can achieve good energy resolution, high detection efficiency, and room-temperature operation. We are working to address each of these requirements through the development of large volume SrI{sub 2}(Eu) scintillator detectors. In this work, we have evaluated a variety of SrI{sub 2} crystals with volumes >10 cm{sup 3}. The goal of this research was to examine the causes of energy resolution degradation for larger detectors and to determine what can be done to mitigate these effects. Testing both packaged and unpackaged detectors, we have consistently achieved better resolution with the packaged detectors. Using a collimated gamma-ray source, it was determined that better energy resolution for the packaged detectors is correlated with better light collection uniformity. A number of packaged detectors were fabricated and tested and the best spectroscopic performance was achieved for a 3% Eu doped crystal with an energy resolution of 2.93% FWHM at 662keV. Simulations of SrI{sub 2}(Eu) crystals were also performed to better understand the light transport physics in scintillators and are reported. This study has important implications for the development of SrI{sub 2}(Eu) detectors for national security purposes.

  18. Pechini synthesis of lanthanide (Eu3+/Tb3+or Dy3+) ions activated BaGd2O4 nanostructured phosphors: an approach for tunable emissions.

    PubMed

    Seeta Rama Raju, G; Pavitra, E; Yu, Jae Su

    2014-09-14

    Trivalent lanthanide (Eu(3+), Tb(3+) and Dy(3+)) ions activated tunable color emitting BaGd2O4 (BG) phosphors were synthesized by a facile Pechini-type sol-gel process. The X-ray diffraction pattern confirmed the orthorhombic phase after annealing at 1300 °C for 5 h. Morphological studies were performed based on the analysis of transmission electron microscopy images, which showed needle type nanorods. The BG phosphor exhibited good photoluminescence (PL) properties in the respective regions when doped with Eu(3+), Tb(3+) and Dy(3+) ions. The Eu(3+) co-activated BG:Tb(3+) phosphor yielded tunable emissions including tri-band established white light emission based on the co-activator concentration and excitation wavelength. The energy transfer from Tb(3+) to Eu(3+) ions was controlled by selecting a suitable excitation wavelength and the decay measurements were carried out for analyzing the energy transfer efficiency. The cathodoluminescence properties of these phosphors were almost similar to PL properties when doped with individual Eu(3+), Tb(3+), and Dy(3+) ions, but were different when co-doped with Eu(3+)/Tb(3+) or Eu(3+)/Dy(3+) ions. In the case of Eu(3+)/Tb(3+) doped samples, the energy transfer process occurred unlike the PL channel. The calculated Commission International de l'Eclairage chromaticity coordinates of individual ion doped BG phosphors confirmed red, green, and white emissions and for co-doped samples they showed tunable emission. PMID:25052006

  19. Localized surface plasmon enhanced cathodoluminescence from Eu3+-doped phosphor near the nanoscaled silver particles.

    PubMed

    Lee, Seong Min; Choi, Kyung Cheol; Kim, Dong Hyuk; Jeon, Duk Young

    2011-07-01

    We elucidate that the luminescence from Eu3+-doped phosphor excited by the electron collision can be modified on location near the metallic nanoparticles. The Eu3+-doped phosphor was fabricated on the nanoscaled Ag particles ranging of 5 nm to 30 nm diameter. As a result of the cathodoluminescence measurements, the phosphor films on the Ag particles showed up to twofold more than that of an isolated phosphor film. Enhanced cathodoluminescence originated from the resonant coupling between the localized surface plasmon of Ag nanoparticles and radiating energy of the phosphor. Cathodoluminescent phosphor for high luminous display devices can be addressed by locating phosphor near the surface of metallic nanoparticles. PMID:21747476

  20. Unpacking "Health Reform" and "Policy Capacity"

    PubMed Central

    Legge, David; Gleeson, Deborah H

    2015-01-01

    Health reform is the outcome of dispersed policy initiatives in different sectors, at different levels and across time. Policy work which can drive coherent health reform needs to operate across the governance structures as well as the institutions that comprise healthcare systems. Building policy capacity to support health reform calls for clarity regarding the nature of such policy work and the elements of policy capacity involved; and for evidence regarding effective strategies for capacity building. PMID:26673185

  1. The English and Swedish health care reforms.

    PubMed

    Glennerster, H; Matsaganis, M

    1994-01-01

    England and Sweden have two of the most advanced systems of universal access to health care in the world. Both have begun major reforms based on similar principles. Universal access and finance from taxation are retained, but a measure of competition between providers of health care is introduced. The reforms therefore show a movement toward the kind of approach advocated by some in the United States. This article traces the origins and early results of the two countries' reform efforts. PMID:8034391

  2. What does Brexit mean for nursing and our EU staff?

    PubMed

    Flynn, Hannah; Kendall-Raynor, Petra; Longhurst, Chris

    2016-06-29

    Currently there is free movement of labour and mutual recognition of nurse training and qualifications between EU member states. This means UK hospitals can actively recruit nurses from across the EU to cover staff shortfalls. So what now? PMID:27353905

  3. Photoluminescence of Vanadate Garnet Ca2NaMg(2-x)V3O12:xEu3+ Phosphors Synthesized by Solution Combustion Method.

    PubMed

    Kim, H; Kim, J; Lim, S; Park, K

    2016-02-01

    In this study, a series of nano-sized Ca2NaMg(2-x)V3O12:xEu3+ (0.06 < or = x < or = 0.18) red phosphors is synthesized by solution combustion method. The microstructure and photoluminescence properties of the Ca2NaMg(2-x)V3O12:xEu3+ phosphors are studied in accordance with the Eu3+ content. Annealed Ca2NaMg(2-x)V3O12:xEu3+ phosphors form a single phase with the cubic garnet structure and Ia3d space group. The emission from (VO4)3- in the Ca2NaMg(2-x)V3O12:xEu3+ phosphors is almost completely quenched due to the efficient energy transfer from the (VO4)3- to the Eu3+ ions. The emission intensity increases sharply with the increased Eu3+ content, reaching a maximum value at x = 0.15, and then decreases with further Eu3+ content. Ca2NaMg1.85V3O12:0.15Eu3+ shows great potential as a red phosphor for white light-emitting diodes. PMID:27433680

  4. Negative Valve Overlap Reforming Chemistry in Low-Oxygen Environments

    SciTech Connect

    Szybist, James P; Steeper, Richard R.; Splitter, Derek A; Kalaskar, Vickey B; Pihl, Josh A; Daw, C Stuart

    2014-01-01

    Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion. When fuel is injected into O2-deficient NVO conditions, a portion of the fuel can be converted to products containing significant levels of H2 and CO. Additionally, other short chain hydrocarbons are produced by means of thermal cracking, water-gas shift, and partial oxidation reactions. The present study experimentally investigates the fuel reforming chemistry that occurs during NVO. To this end, two very different experimental facilities are utilized and their results are compared. One facility is located at Oak Ridge National Laboratory, which uses a custom research engine cycle developed to isolate the NVO event from main combustion, allowing a steady stream of NVO reformate to be exhausted from the engine and chemically analyzed. The other experimental facility, located at Sandia National Laboratories, uses a dump valve to capture the exhaust from a single NVO event for analysis. Results from the two experiments are in excellent trend-wise agreement and indicate that the reforming process under low-O2 conditions produces substantial concentrations of H2, CO, methane, and other short-chain hydrocarbon species. The concentration of these species is found to be strongly dependent on fuel injection timing and injected fuel type, with weaker dependencies on NVO duration and initial temperature, indicating that NVO reforming is kinetically slow. Further, NVO reforming does not require a large energy input from the engine, meaning that it is not thermodynamically expensive. The implications of these results on HCCI and other forms of combustion are discussed in detail.

  5. Being a Player in Teacher Education Reform.

    ERIC Educational Resources Information Center

    Johns, Jerry L.

    2003-01-01

    Presents a letter to Governors from the president of the International Reading Association addressing an increased discussion about teacher preparation programs and calls for teacher education reform. (SG)

  6. Healthcare Reform 2010- a surgeon's perspective.

    PubMed

    Ullyot, Daniel J

    2010-01-01

    The Patient Protection and Affordable Care Act (PPACA) was signed into law President Barack Obama in March 2010. From the standpoint of a clinical surgeon, Dan Ullyot examines healthcare reform of the US system and asks: What is healthcare reform? Do we need it? What would ideal reform look like? And to what extent does the PPACA approach ideal reform? This article is a primer for understanding the salient features of this complex piece of federal legislation, which will have an enormous influence on the lives of this generation and those of the future. PMID:21928185

  7. Single crystals of the fluorite nonstoichiometric phase Eu{sub 0.916}{sup 2+}Eu{sub 0.084}{sup 3+}F{sub 2.084} (conductivity, transmission, and hardness)

    SciTech Connect

    Sobolev, B. P. Turkina, T. M.; Sorokin, N. I.; Karimov, D. N.; Komar'kova, O. N.; Sulyanova, E. A.

    2010-07-15

    The nonstoichiometric phase EuF{sub 2+x} has been obtained via the partial reduction of EuF{sub 3} by elementary Si at 900-1100 deg. C. Eu{sub 0.916}{sup 2+}Eu{sub 0.084}{sup 3+}F{sub 2.084} (EuF{sub 2.084}) single crystals have been grown from melt by the Bridgman method in a fluorinating atmosphere. These crystals belong to the CaF{sub 2} structure type (sp. gr. Fm3-barm) with the cubic lattice parameter a = 5.8287(2) A, are transparent in the spectral range of 0.5-11.3 {mu}m, and have microhardness H{sub {mu}} = 3.12 {+-} 0.13 GPa and ionic conductivity {sigma} = 1.4 x 10{sup -5} S/cm at 400 deg. C with the ion transport activation energy E{sub a} = 1.10 {+-} 0.05 eV. The physicochemical characteristics of the fluorite phases in the EuF{sub 2} - EuF{sub 3} systems are similar to those of the phases in the SrF{sub 2} - EuF{sub 3} and SrF{sub 2} - GdF{sub 3} systems due to the similar lattice parameters of the EuF{sub 2} and SrF{sub 2} components. Europium difluoride supplements the list of fluorite components MF{sub 2} (M = Ca, Sr, Ba, Cd, Pb), which are crystal matrices for nonstoichiometric (nanostructured) fluoride materials M{sub 1-x}R{sub x}F{sub 2+x} (R are rare earth elements).

  8. Synthesis and Magnetic Properties of Gd Doped EuS Nanocrystals with Enhanced Curie Temperatures

    SciTech Connect

    Selinsky, Rachel S.; Han, Jae Hyo; Perez, Elvin A. Morales; Guzei, Ilia A.; Jin, Song

    2010-12-07

    EuS nanocrystals (NCs) were doped with Gd resulting in an enhancement of their magnetic properties. New EuS and GdS single source precursors (SSPs) were synthesized, characterized, and employed to synthesize Eu{sub 1-x}Gd{sub x}S NCs by decomposition in oleylamine and trioctylphosphine at 290 C. The doped NCs were characterized using X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy, which support the uniform distribution of Gd dopants through electron energy loss spectroscopy (EELS) mapping. X-ray absorption spectroscopy (XAS) revealed the dopant ions in Eu{sub 1-x}Gd{sub x}S NCs to be predominantly Gd{sup 3+}. NCs with a variety of doping ratios of Gd (0 {le} x < 1) were systematically studied using vibrating sample magnetometry and the observed magnetic properties were correlated with the Gd doping levels (x) as quantified with ICP-AES. Enhancement of the Curie temperature (T{sub C}) was observed for samples with low Gd concentrations (x {le} 10%) with a maximum T{sub C} of 29.4 K observed for NCs containing 5.3% Gd. Overall, the observed T{sub C}, Weiss temperature ({theta}), and hysteretic behavior correspond directly to the doping level in Eu{sub 1-x}Gd{sub x}S NCs and the trends qualitatively follow those previously reported for bulk and thin film samples.

  9. Analysis of surface properties of semiconducting (Ti,Pd,Eu)Ox thin films

    NASA Astrophysics Data System (ADS)

    Wojcieszak, D.; Kaczmarek, D.; Domaradzki, J.

    2016-01-01

    In this paper an analysis of the surface properties of(Ti,Pd,Eu)Ox thin films prepared by magnetron sputtering has been described. In particular, the results of composition and structure investigations were studied in relation to the surface state and optical properties. It was found that (Ti,Pd,Eu)Oxfilm was nanocrystalline and had a rutile structure. The average crystallites size was equal to 7.8 nm. Films were homogeneous and had densely packed grains. Investigation of the surface properties by XPS showed that titanium was present at 4+ state (in the TiO2form), palladium occurred as PdO2 (also at 4+ state), while europium was in Eu2O3form (at 3+ state). In comparison with the unmodified TiO2, the coating with Pd and Eu additives had a rather high transparency (approx. 47%) in the visible light range, its optical absorption edge was shifted towards into the longer wavelengths (from 345 nm to 452 nm), and the width of optical energy gap Egopt was nearly twice lower (1.82 eV). Besides, the resistivity of(Ti,Pd,Eu)Ox at room temperature was 1x103 Wcm. In the case of the film as-deposited on Si substrate (p-type) the generation of photocurrent as a response to light beam excitation ( Ảexc = 527 nm) was observed.

  10. Analysis of surface properties of semiconducting (Ti,Pd,Eu)Ox thin films

    NASA Astrophysics Data System (ADS)

    Wojcieszak, D.; Kaczmarek, D.; Domaradzki, J.

    2016-01-01

    In this paper an analysis of the surface properties of (Ti,Pd,Eu)Ox thin films prepared by magnetron sputtering has been described. In particular, the results of composition and structure investigations were studied in relation to the surface state and optical properties. It was found that (Ti,Pd,Eu)Ox film was nanocrystalline and had a rutile structure. The average crystallites size was equal to 7.8 nm. Films were homogeneous and had densely packed grains. Investigation of the surface properties by XPS showed that titanium was present at 4+ state (in the TiO2 form), palladium occurred as PdO2 (also at 4+ state), while europium was in Eu2O3 form (at 3+ state). In comparison with the unmodified TiO2, the coating with Pd and Eu additives had a rather high transparency (approx. 47%) in the visible light range, its optical absorption edge was shifted towards into the longer wavelengths (from 345 nm to 452 nm), and the width of optical energy gap Egopt was nearly twice lower (1.82 eV). Besides, the resistivity of (Ti,Pd,Eu)Ox at room temperature was 1x103 Wcm. In the case of the film as-deposited on Si substrate (p-type) the generation of photocurrent as a response to light beam excitation (λexc = 527 nm) was observed.

  11. Synthesis and Magnetic Properties of Gd Doped EuS Nanocrystals with Enhanced Curie Temperatures

    PubMed Central

    Selinsky, Rachel S.; Han, Jae Hyo; Morales Pérez, Elvin A.; Guzei, Ilia A.; Jin, Song

    2010-01-01

    EuS nanocrystals (NCs) were doped with Gd resulting in an enhancement of their magnetic properties. New EuS and GdS single source precursors (SSPs) were synthesized, characterized, and employed to synthesize Eu1-xGdxS NCs by decomposition in oleylamine and trioctylphosphine at 290 °C. The doped NCs were characterized using X-ray diffraction, transmission electron miscroscopy and scanning transmission electron microscopy, which supports the uniform distribution of Gd dopants through electron energy loss spectroscopy (EELS) mapping. X-ray absorption spectroscopy (XAS) revealed the dopant ions in Eu1-xGdxS NCs to be predominantly Gd3+. NCs with a variety of doping ratios of Gd (0 ≤ x < 1) were systematically studied using vibrating sample magnetometry and the observed magnetic properties were correlated with the Gd doping levels (x) as quantified with ICP-AES. Enhancement of the Curie temperature (TC) was observed for samples with low Gd concentrations (x ≤ 10 %) with a maximum TC of 29.4 K observed for NCs containing 5.3 % Gd. Overall, the observed TC, Weiss temperature (θ), and hysteretic behavior correspond directly to the doping level in Eu1-xGdxS NCs and the trends qualitatively follow those previously reported for bulk and thin film samples. PMID:20964293

  12. A novel LiCl-BaCl2:Eu2+ eutectic scintillator for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Wu, Yuntao; Lukosi, Eric D.; Zhuravleva, Mariya; Lindsey, Adam C.; Melcher, Charles L.

    2015-10-01

    A natLiCl-BaCl2:Eu2+ eutectic scintillator was synthesized by the vertical Bridgman method aiming at the application of thermal neutron detection. The molar ratio of LiCl and BaCl2 was 75.1/24.9, which corresponds to the eutectic composition in the LiCl-BaCl2 system. The grown eutectic showed a periodic microstructure of BaCl2:Eu2+ and LiCl phases with 2-3 μm thickness. The α-particle induced radioluminescence spectrum of the scintillator showed an intense emission peak at 406 nm due to the Eu2+ 5d1→4f emission from the BaCl2:Eu2+ phase and an additional weak emission peak at 526 nm. The scintillation decay time was 412 ns. LiCl-BaCl2:Eu2+ eutectic samples exhibited non-correlated neutron detection efficiency and light yield as a function of crystal length, suggesting material non-uniformities within the boule. The relative light yield was equal to or greater than that of Nucsafe lithium glass. Gamma-ray exposures indicate that gamma/neutron threshold discrimination for higher energy gamma-rays will be limited.

  13. Luminescence studies on SrMgAl 10O 17:Eu, Dy phosphor crystals

    NASA Astrophysics Data System (ADS)

    Wanjun, Tang; Donghua, Chen; Ming, Wu

    2009-02-01

    Using urea as fuel, SrMgAl 10O 17:Eu, Dy phosphor was prepared by a combustion method. Its luminescence properties under ultraviolet (UV) excitation were investigated. Pure SrMgAl 10O 17 phase was formed by urea-nitrate solution combustion synthesis at 550 °C. The results indicated that the emission spectra of SrMgAl 10O 17:Eu, Dy has one main peak at 460 nm and one shoulder peak near 516 nm, which are ascribed to two different types of luminescent Eu 2+ centers existing in the SrMgAl 10O 17 matrix crystal. The blue luminescence emission of SrMgAl 10O 17:Eu phosphors was improved under UV excitation by codoping Dy 3+ ions. The SrMgAl 10O 17:Eu phosphors showed green afterglow ( λ=516 nm) when Dy 3+ ions were doped. Dy 3+ ions not only successfully play the role of sensitizer for energy transfer in the system, but also act as trap levels and capture the free holes in the spinel blocks.

  14. Mechanoluminescence properties of SrAl2 O4 :Eu(2+) phosphor by combustion synthesis.

    PubMed

    Bisen, D P; Sharma, R

    2016-03-01

    In this paper, europium-doped strontium aluminate (SrAl2 O4 :Eu(2+) ) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2 O4 :Eu(2+) phosphor. The optical properties of SrAl2 O4 :Eu(2+) phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2 O4 :Eu(2+) phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2 O4 :Eu(2+) phosphor emitted green coloured light. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26198971

  15. Synthesis and magnetic properties of Gd doped EuS nanocrystals with enhanced Curie temperatures.

    PubMed

    Selinsky, Rachel S; Han, Jae Hyo; Morales Pérez, Elvin A; Guzei, Ilia A; Jin, Song

    2010-11-17

    EuS nanocrystals (NCs) were doped with Gd resulting in an enhancement of their magnetic properties. New EuS and GdS single source precursors (SSPs) were synthesized, characterized, and employed to synthesize Eu(1-x)Gd(x)S NCs by decomposition in oleylamine and trioctylphosphine at 290 °C. The doped NCs were characterized using X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy, which support the uniform distribution of Gd dopants through electron energy loss spectroscopy (EELS) mapping. X-ray absorption spectroscopy (XAS) revealed the dopant ions in Eu(1-x)Gd(x)S NCs to be predominantly Gd(3+). NCs with a variety of doping ratios of Gd (0 ≤ x < 1) were systematically studied using vibrating sample magnetometry and the observed magnetic properties were correlated with the Gd doping levels (x) as quantified with ICP-AES. Enhancement of the Curie temperature (T(C)) was observed for samples with low Gd concentrations (x ≤ 10%) with a maximum T(C) of 29.4 K observed for NCs containing 5.3% Gd. Overall, the observed T(C), Weiss temperature (θ), and hysteretic behavior correspond directly to the doping level in Eu(1-x)Gd(x)S NCs and the trends qualitatively follow those previously reported for bulk and thin film samples. PMID:20964293

  16. Synthesis, Structure, and Spectroscopy of Epitaxial EuFeO3 Thin Films

    SciTech Connect

    Choquette, Amber K.; Colby, Robert J.; Moon, E. J.; Schleputz, C. M.; Scafetta, Mark D.; Keavney, David J.; May, Steven J.

    2015-03-04

    Rare earth iron perovskites RFeO3, where R is a rare earth cation, exhibit an array of magnetic, catalytic, optical and electrochemical properties. Here we study EuFeO3 films synthesized by molecular beam epitaxy in order to better understand the optical properties of ferrites. A combination of x-ray diffraction, x-ray reflectivity, Rutherford backscattering spectroscopy, and scanning transmission electron microscopy were used to characterize the film structure and cation composition. X-ray absorption spectroscopy confirms the nominal 3+ valence states of Eu and Fe. The optical properties of EuFeO3 were investigated using variable angle spectroscopic ellipsometry between the phonon energies of 1.25 to 5 eV. We find that EuFeO3 is a semiconductor with an onset of optical absorption near 2.5 eV. The absorption spectrum of EuFeO3 is blue-shifted with respect to LaFeO3 films, a result that is attributed to the structural differences of the two materials.

  17. Teachers' Response to Standards-Based Reform: Probing Reform Assumptions in Washington State

    ERIC Educational Resources Information Center

    Loeb, Hilary; Knapp, Michael S.; Elfers, Ana M.

    2008-01-01

    Because teachers' efforts are central to the success of standards-based reform, it behooves the policy community to look carefully at the beliefs about instruction that are rooted in this reform theory. Building on teacher-centric research on standards-based reform and ideas about teaching practice from research on multicultural education, this…

  18. Toward Reform in Land Reform: Coupling Local Control and Social Control.

    ERIC Educational Resources Information Center

    Geisler, Charles C.

    An alternative to the traditional land reform movement in the United States and the recent land use reform movement would result in a merging of social control with local control over land. Traditional land reformers perceive that land is a private commodity subject to fee-simple ownership and near absolute control over its use and disposition.…

  19. Reforming Districts: How Districts Support School Reform. A Research Report. Document R-03-6

    ERIC Educational Resources Information Center

    McLaughlin, Milbrey; Talbert, Joan

    2003-01-01

    School districts have participated in multiple rounds of education reform activity in the past few decades, yet few have made headway on system-wide school improvement. This paper addresses the questions of whether districts matter for school reform progress and what successful "reforming" districts do to achieve system change and to navigate the…

  20. Education Reform and Students At Risk. Volume I: Findings and Recommendations. Studies of Education Reform.

    ERIC Educational Resources Information Center

    Rossi, Robert J.; Stringfield, Samuel C.

    Despite the widespread attention given to education reform, no substantial knowledge base has existed for identifying and implementing specific effective reforms. This document, the first of three volumes, presents findings of a study that sought to identify the essential mechanics of effective reforms for students at risk. The study also…

  1. Photophysical properties and biocompatibility of Photoluminescent Y2O3:Eu nanoparticles in polymethylmetacrylate matrix.

    PubMed

    Abe, Shigeaki; Hamba, Yusuke; Iwadera, Nobuki; Yamagata, Shuichi; Yawaka, Yasutaka; Uo, Motohiro; Iida, Junichiro; Kiba, Takayuki; Murayama, Akihiro; Watari, Fumio

    2014-04-01

    In this study, we produced europium-doped yttoria (Y2O3:Eu) nanoparticles and investigated their photoluminescent properties and biocompatibility. The Y2O3:Eu nanoparticles showed excellent photoluminescent properties and cytocompatibility. We also analyzed the photophysical properties of the nanoparticles in PMMA films. When the Y2O3:Eu nanoparticles were incorporated in the polymer film, they showed a strong red emission spectrum, similar to that seen with the particles alone. Energy dispersive X-ray spectroscopy (EDS) measurements indicated that the particles were distributed homogeneously in the PMMA film. Such materials could be applied not only to optoelectronic devices but also to biomedical applications such as bioimaging tools or luminescent medical/dental adhesive materials. PMID:24734706

  2. Investigation of the Statistical Properties of Stable Eu Nuclei using Neutron-Capture Reactions

    SciTech Connect

    Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R; Esch, E; Folden, III, C M; Hatarik, R; Haight, R C; Hoffman, D C; Krticka, M; Macri, R A; Mitchell, G E; Nitsche, H; O'Donnell, J M; Parker, W; Reifarth, R; Rundberg, R S; Schwantes, J M; Sheets, S A; Ullmann, J L; Vieira, D J; Wilhelmy, J B; Wilk, P; Wouters, J M; Wu, C Y

    2005-10-04

    Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. The highly efficient DANCE (Detector for Advanced Neutron Capture Experiments) array coupled with the intense neutron beam at Los Alamos Neutron Science Center is used for the experiment. Stable Eu isotopes mass separated and electroplated on Be backings were used. Properties of well-resolved, strong resonances in two Eu nuclei are examined. The parameters for most of these resonances are known. Detailed multiplicity information for each resonance is obtained employing the high granularity of the DANCE array. The radiative decay cascades corresponding to each resonance are obtained in the experiment. The measurements are compared to simulation of these cascades which calculated with various models for the radiative strength function. Comparison between the experimental data and simulation provides an opportunity to investigate the average quantities.

  3. Fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses containing lithium, zinc and lead.

    PubMed

    Venkatramu, V; Babu, P; Jayasankar, C K

    2006-02-01

    The influence of glass composition on the fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses modified with Li+, Zn2+ and Pb2+ cations have been investigated. The magnitude of splittings of 7F1 levels are analyzed using crystal-field (CF) analysis. The relative intensities of 5D0 --> 7F2 to 5D0 --> 7F1 transitions, crystal-field strength parameters and decay times of the 5D0 level have been determined and are found to be lower for Pb based glasses than those of Zn/Li based glasses. The lifetimes of 5D0 level are found to increase when borate glasses are modified with pure fluorides than with oxides and oxyfluorides. The fluorescence decay of 5D0 level fits perfect single exponential in the Eu3+:glass systems studied which indicates the absence of energy transfer between Eu3+ ions in these glasses. PMID:15979397

  4. TL and OSL of SrSO4 phosphors doped with Eu.

    PubMed

    Tang, Q; Zhang, C X; Luo, D L; Leung, P L; Xiong, Z Y

    2006-01-01

    The thermoluminescence (TL) and optically stimulated luminescence (OSL) of SrSO4:Eu (0.1 mol%) powder sample were studied. The TL and OSL emission spectrum are measured after irradiation (absorbed dose 100 Gy) of 90Sr source; both of them showed that the emission wavelength is at approximately 375 nm, which indicates that TL and OSL have the same luminescence centres, and the luminescence comes from transitions between the energy levels of Eu2+. The TL glow curves and OSL decay curves illustrate that there is only one main TL peak but two main components in OSL curves. By a comparative study of TL and OSL it is concluded that OSL traps are different from TL traps. The TL and OSL dose responses of SrSO4:Eu phosphor were measured, and it showed that phosphor has similar dose responses for OSL and TL. PMID:16644983

  5. Synthesis and luminescence properties of KSrPO4:Eu2+ phosphor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Palan, C. B.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The KSrPO4:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO4:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO4:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al2O3:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activation energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.

  6. The EU Dimension to Soil Science in Schools

    ERIC Educational Resources Information Center

    Johnson, Sue

    2012-01-01

    The EU as a context for science lessons may be given scant attention but EU decision-making is a vital factor in everyday life. Lessons on the emergence of soil science with Charles Darwin's simple scientific experiments can be linked with competence through action, inclusion and argumentations in science lessons. Decisions about an EU Soil…

  7. Development of Zn and Eu beams by plasma sputtering

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Rodrigues, G.; Kanjilal, D.; Roy, A.; Singh, Beer Pal; Kumar, R.

    2006-05-01

    Accelerated ion beams of various species are important tools to engineer the materials. The low energy ion beam facility (LEIBF) at Nuclear Science Centre (NSC) provides the ion beams of energy in the range of a few keV to a few MeV. The LEIBF is fully operational since 2001 and its performance has been tested very well with ion beams from noble gases. Metallic and rare earth ion beams have important role in the field of nano-technology and enhancement of optical properties of semiconducting nano-particles inside various matrices. During the last few years, an effort was made to extract ion beams of various metal and rare earth elements using different techniques. Here we describe the successful development of Zn and Eu ion beams using sputtering technique in electron cyclotron resonance (ECR) ion source. Operational experience to produce such kind of beams and results on beam analysis are described in the paper.

  8. Comparative study on Climate Change Policies in the EU and China

    NASA Astrophysics Data System (ADS)

    Bray, M.; Han, D.

    2012-04-01

    Both the EU and China are among the largest CO2 emitters in the world; their climate actions and policies have profound impacts on global climate change and may influence the activities in other countries. Evidence of climate change has been observed across Europe and China. Despite the many differences between the two regions, the European Commission and Chinese government support climate change actions. The EU has three priority areas in climate change: 1) understanding, monitoring and predicting climate change and its impact; 2) providing tools to analyse the effectiveness, cost and benefits of different policy options for mitigating climate change and adapting to its impacts; 3) improving, demonstrating and deploying existing climate friendly technologies and developing the technologies of the future. China is very vulnerable to climate change, because of its vast population, fast economic development, and fragile ecological environment. The priority policies in China are: 1) Carbon Trading Policy; 2) Financing Loan Policy (Special Funds for Renewable Energy Development); 3) Energy Efficiency Labelling Policy; 4) Subsidy Policy. In addition, China has formulated the "Energy Conservation Law", "Renewable Energy Law", "Cleaner Production Promotion Law" and "Circular Economy Promotion Law". Under the present EU Framework Programme FP7 there is a large number of funded research activities linked to climate change research. Current climate change research projects concentrate on the carbon cycle, water quality and availability, climate change predictors, predicting future climate and understanding past climates. Climate change-related scientific and technological projects in China are mostly carried out through national scientific and technological research programs. Areas under investigation include projections and impact of global climate change, the future trends of living environment change in China, countermeasures and supporting technologies of global

  9. Time-resolved study of luminescence in soda-lime silicate glasses co-doped with Gd 3+ and Eu 3+

    NASA Astrophysics Data System (ADS)

    Kondo, Yasutaka; Tanaka, Katsuhisa; Ota, Rikuo; Fujii, Tomoki; Ishikawa, Yo-ichi

    2005-05-01

    Energy transfer process in soda-lime glasses co-doped with Gd 3+ and Eu 3+, where a ground state of Gd 3+, 8S 7/2, was selectively excited to a 6I J state by a 275-nm pulsed laser irradiation, was studied based on a time-resolved luminescence spectroscopy. The luminescence decay rate at 313 nm (Gd 3+: 6P 7/2 → 8S 7/2) was observed to be (1.5 ± 0.2) × 10 2 s -1 ( τ = 6.6 ± 0.6 ms) without Eu 3+ and to increase monotonously with increasing co-doped Eu 3+ concentration, giving an apparent quenching rate constant of (5.0 ± 0.5) × 10 -18 ion -1 cm 3 s -1 (≈(1.9 ± 0.2) × 10 3 mol% -1 s -1) for a 6P 7/2 state of Gd 3+ ion with Eu 3+. The relaxation rate of a 6I J state to a luminescent state 6P 7/2 in Gd 3+ ion was estimated to be (1.8 ± 0.2) × 10 6 s -1 from the rise rate at 313-nm luminescence ( τrise ≈ 0.56 μs), which was observed to be almost independent of the Eu 3+ concentration. The luminescence intensity from Eu 3+ at 591 nm and 613 nm monotonously increased with increasing Eu 3+ concentration up to 0.33-mol% Eu 3+, while it started decreasing at concentration of Eu 3+ higher than 0.33-mol%, which was interpreted in terms of the resonant energy transfer to nearby Eu 3+ resulting in the excitation to the Eu 3+-O - charge transfer states.

  10. Experimental and computational investigations of sulfur-resistant bimetallic catalysts for reforming of biomass gasification products

    SciTech Connect

    Rangan, Meghana; Yung, Matthew M.; Medlin, J. William

    2011-11-17

    A combination of density functional theory (DFT) calculations and experimental studies of supported catalysts was used to identify H{sub 2}S-resistant biomass gasification product reforming catalysts. DFT calculations were used to search for bimetallic, nickel-based (1 1 1) surfaces with lower sulfur adsorption energies and enhanced ethylene adsorption energies. These metrics were used as predictors for H{sub 2}S resistance and activity toward steam reforming of ethylene, respectively. Relative to Ni, DFT studies found that the Ni/Sn surface alloy exhibited enhanced sulfur resistance and the Ni/Ru system exhibited an improved ethylene binding energy with a small increase in sulfur binding energy. A series of supported bimetallic nickel catalysts was prepared and screened under model ethylene reforming conditions and simulated biomass tar reforming conditions. The observed experimental trends in activity were consistent with theoretical predictions, with observed reforming activities in the order Ni/Ru > Ni > Ni/Sn. Interestingly, Ni/Ru showed a high level of resistance to sulfur poisoning compared with Ni. This sulfur resistance can be partly explained by trends in sulfur versus ethylene binding energy at different types of sites across the bimetallic surface.

  11. Study of Defects in GaN In Situ Doped with Eu3+ Ion Grown by OMVPE

    NASA Astrophysics Data System (ADS)

    Wang, Jingzhou; Koizumi, Atsushi; Fujiwara, Yasufumi; Jadwisienczak, Wojciech M.

    2016-04-01

    In this work, GaN epilayer in situ doped with Eu3+ ions was deposited on the top of an undoped n-GaN/LT-GaN/sapphire structure by organometallic vapor-phase epitaxy. A set of different ohmic and Schottky contacts on GaN:Eu3+ surface was fabricated by electron-beam evaporation for performing deep level transient spectroscopy (DLTS) measurement. The deep defect energy levels in GaN:Eu3+ epilayer were assessed by standard DLTS and high resolution Laplace DLTS (L-DLTS). Three dominant DLTS peaks were observed in the temperature range from 35 K to 400 K. The calculated activation energies of these defect energy levels were 0.108 ± 0.03 eV (Trap A), 0.287 ± 0.04 eV (Trap B) and 0.485 ± 0.06 eV (Trap C) below conduction band edge, respectively. High resolution L-DLTS conducted for the GaN:Eu3+ epilayer revealed at least four closely spaced defect energy levels associated with Trap B. It is proposed that these defect energy levels correspond to the selected optically active Eu3+ ion centers in GaN host previously identified by optical studies in this material (Fujiwara and Dierolf in Jpn J Appl Phys 53:05FA13, 2014).

  12. A MEMS-based reformed methanol fuel cell for portable power

    NASA Astrophysics Data System (ADS)

    Morse, J. D.; Upadhye, R. S.; Graff, R. T.; Spadaccini, C.; Park, H. G.; Hart, E. K.

    2007-09-01

    A reformed methanol fuel cell system is described. The use of a microfluidic fuel processor enables component scaling and integration sufficient to achieve power sources in the 2 10 W regime that are competitive in size and energy density in comparison to alternative power sources. While carbon monoxide tolerance of proton conducting membranes has typically limited the performance of reformed methanol fuel cells, phosphoric-acid-doped polybenzimidazole (PBI) membranes have been tested that exhibit no degradation for carbon monoxide >2% mole fraction. Further benefits of the PBI membrane include operating temperature of 150 200 °C, and no need for water to assist protonic conduction. As a result, a chemically and thermally robust fuel cell power source is realized. Results of methanol steam reforming and catalytic combustor heating elements formed in a silicon MEMS platform, and PBI membrane performance with reformate fuel feed will be discussed.

  13. Medical liability reform crisis 2008.

    PubMed

    Weinstein, Stuart L

    2009-02-01

    The crisis of medical liability has resulted in drastic increases in insurance premiums and reduced access for patients to specialty care, particularly in areas such as obstetrics/gynecology, neurosurgery, and orthopaedic surgery. The current liability environment neither effectively compensates persons injured from medical negligence nor encourages addressing system errors to improve patient safety. The author reviews trends across the nation and reports on the efforts of an organization called "Doctors for Medical Liability Reform" to educate the public and lawmakers on the need for solutions to the chaotic process of adjudicating medical malpractice claims in the United States. PMID:18989732

  14. Spectroscopic evidence of the multiple- site structure of Eu(3+) ions incorporated in ZnO nanocrystals.

    PubMed

    Liu, Yongsheng; Luo, Wenqin; Li, Renfu; Chen, Xueyuan

    2007-03-01

    Hexagonal Eu(3+):ZnO nanocrystals were synthesized by a modified solgel method. By means of the site-selective spectroscopy at 10 K, two kinds of luminescence sites of Eu(3+) are identified. One site exhibits a long lifetime of (5)D(0) and sharp emission and excitation peaks, which are ascribed to the inner lattice site with an ordered crystalline environment. The other site associated with the distorted lattice sites near the surface shows a relatively short lifetime of (5)D(0) and significantly broadened fluorescence lines. The energy transfer from the nanocrystal host to Eu(3+) confirms that Eu(3+) ions can, to some extent, be incorporated into the ZnO nanocrystal. PMID:17392923

  15. Ultraviolet-to-visible downconversion luminescence in solgel oxyfluoride glass ceramics containing Eu³⁺:GdF₃ nanocrystals.

    PubMed

    Szpikowska-Sroka, Barbara; Zur, Lidia; Czoik, Rozalia; Goryczka, Tomasz; Ządło, Maria; Pisarski, Wojciech A

    2014-06-01

    GdF3 nanocrystals doped with Eu3+ ions in oxyfluoride glass ceramics were prepared by a solgel method. The structural properties were examined by x-ray diffraction measurements. The effects of gadolinium codoping on europium emission in the prepared solgel glasses and glass ceramics have been studied. The emission bands originating from the 5D0 state of Eu3+ ions are enhanced under excitation of Gd3+ ions by 273 nm line. The electric dipole 5D0→7F2 transitions were dominant in the samples before heat treatment, whereas magnetic dipole 5D0→7F1 transitions had a higher probability in the samples after annealing. The luminescence lifetime for the 5D0 level of Eu3+ ions in the samples after excitation at 273 nm is long lived in comparison to excitation at 393 nm and increased to 190%. Energy transfer from Gd3+ to Eu3+ was observed. PMID:24876007

  16. Spectroscopic evidence of the multiple-site structure of Eu3+ ions incorporated in ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Liu, Yongsheng; Luo, Wenqin; Li, Renfu; Chen, Xueyuan

    2007-03-01

    Hexagonal Eu3+:ZnO nanocrystals were synthesized by a modified solgel method. By means of the site-selective spectroscopy at 10 K, two kinds of luminescence sites of Eu3+ are identified. One site exhibits a long lifetime of D05 and sharp emission and excitation peaks, which are ascribed to the inner lattice site with an ordered crystalline environment. The other site associated with the distorted lattice sites near the surface shows a relatively short lifetime of 5D0 and significantly broadened fluorescence lines. The energy transfer from the nanocrystal host to Eu3+ confirms that Eu3+ ions can, to some extent, be incorporated into the ZnO nanocrystal.

  17. Synthesis, characterization and luminescence behavior of ZrO2:Eu3+, Dy3+ with variable concentration of Eu and Dy doped Phosphor

    NASA Astrophysics Data System (ADS)

    Kaur, Jagjeet; Parganiha, Yogita; Dubey, Vikas; Singh, Deepti; Chandrakar, Deepika

    2014-09-01

    The present paper reports thermoluminescence (TL) glow curves and photoluminescence (PL) studies of europium, dysprosium co-doped zirconia (ZrO2:Eu3+, Dy3+). The sample were prepared by the solid state method with variable concentration of Eu (0.5-2 mol%) and Dy (0.5-2 mol%); thereafter, the TL glow curves were recorded for different doses of UV exposure at a heating rate of 6.7 °C s-1. The kinetic parameters activation energy E, the order of kinetics b, and the frequency factor “s” of synthesized phosphors of ZrO2:Eu3+, Dy3+ have been calculated by using a peak shape method. The sample was characterized by XRD (X-ray diffraction), SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy). Effect of Eu and Dy concentration of PL and TL studies are also interpreted. Here the photoluminescence excitation and emission spectra were found at 307 and 395 nm and 594, 612 and 627 nm range respectively. The present phosphor acts as a single host for red emission display devices as well as may be used for thermoluminescence dosimetric material under UV exposure. Commission Internationale de l'éclairage co-ordinate of this nanophosphor (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight.

  18. Preparation and luminescence characteristics of monazite Eu3+:LaPO4 nanocrystals in NH4NO3 molten salt

    NASA Astrophysics Data System (ADS)

    Huang, Xinyang

    2015-12-01

    Molten-salt method and NH4NO3 flux were developed to fabricate monoclinic monazite Eu3+:LaPO4 nanocrystals for the first time. The products were characterized by X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, excitation spectra, emission spectra and luminescence decay curves. The as-obtained products were quasihexagonal Eu3+:LaPO4 nanocrystals with the mean size of 30 nm. The room temperature charge transfer bands (CTB) exhibited red-shift and spectral broadening in comparison with 10 K CTB. The optimal Eu3+ concentration was determined to be 8 mol% by a comparative study of the relative emission intensities for different Eu3+ doping concentrations. The higher concentration quenching could be caused by the possible nonradiative energy transfer (electric multipole-multipole interaction). The relationship between the FL lifetime of 5D0 energy level and Eu3+ concentration was investigated based on Auzel's model. This work is important not only to understand the unique physical properties of Eu3+:LaPO4 nanocrystals but also to bring an opportunity for the development of the other nanocrystals via the molten salt synthesis in NH4NO3 flux.

  19. Photosensized Controlling Benzyl Methacrylate-Based Matrix Enhanced Eu3+ Narrow-Band Emission for Fluorescence Applications

    PubMed Central

    Lee, Jiann-Fong; Chen, Hsuen-Li; Lee, Geneh-Siang; Tseng, Shao-Chin; Lin, Mei-Hsiang; Liau, Wen-Bin

    2012-01-01

    This study synthesized a europium (Eu3+) complex Eu(DBM)3Cl-MIP (DBM = dibenzoyl methane; Cl-MIP = 2-(2-chlorophenyl)-1-methyl-1H-imidazo[4,5-f][1,10]phenanthroline) dispersed in a benzyl methacrylate (BMA) monomer and treated with ultraviolet (UV) light for polymerization. Spectral results showed that the europium complex containing an antenna, Cl-MIP, which had higher triplet energy into the Eu3+ energy level, was an energetically enhanced europium emission. Typical stacking behaviors of π–π interactions between the ligands and the Eu3+-ion were analyzed using single crystal X-ray diffraction. Regarding the luminescence performance of this europium composite, the ligand/defect emission was suppressed by dispersion in a poly-BMA (PBMA) matrix. The underlying mechanism of the effective enhancement of the pure Eu3+ emission was attributed to the combined effects of structural modifications, defect emissions, and carrier charge transfer. Fluorescence spectra were compared to the composite of optimized Eu3+ emission where they were subsequently chelated to four metal ions via carboxylate groups on the BMA unit. The optical enhanced europium composite clearly demonstrated highly efficient optical responses and is, therefore a promising application as an optical detection material. PMID:22489178

  20. Spectroscopy and structural characteristics of Eu3+-activated perovskite tungstate Ba2La2ZnW2O12

    NASA Astrophysics Data System (ADS)

    Yang, Li; Huang, Yanlin; Cheng, Han; Seo, Hyo Jin

    2015-11-01

    Eu3+-doped tungstate Ba2La2ZnW2O12 was prepared by the high-temperature solid-state reaction method. The x-ray powder diffraction (XRD) patterns indicate that the matrix has a perovskite structure. The samples were characterized by the scanning electron microscope (SEM), by optical diffuse reflection, photoluminescence (PL) spectra and by their decay curves. Eu3+-activated Ba2La2ZnW2O12 shows red luminescence under the excitation of near-ultraviolet and blue light. Laser site-selective excitation and emission spectroscopy technology was applied to investigate the spectroscopic and microstructural properties. The excitation spectra were tested by monitoring the emission from 5D0  →  7F0-4 transitions. Accordingly the emission spectra and decay curves (lifetime) were measured by the excitation in the 5D0  →  7F0 wavelength region using a pulsed, tunable, and narrow-band dye laser. We have detected two Eu3+ sites in Ba2La2ZnW2O12 with the temperature region ranging from 10 K to below 300 K. On the spectra data of the site-selective emission and decay, the Stark energy levels of Eu3+ at two different sites were determined. The lifetimes of Eu3+ ions at the two sites were compared. The energy transfer and crystallographic assignments for the Eu3+ sites were discussed.

  1. Mandate-based health reform and the labor market: Evidence from the Massachusetts reform.

    PubMed

    Kolstad, Jonathan T; Kowalski, Amanda E

    2016-05-01

    We model the labor market impact of the key provisions of the national and Massachusetts "mandate-based" health reforms: individual mandates, employer mandates, and subsidies. We characterize the compensating differential for employer-sponsored health insurance (ESHI) and the welfare impact of reform in terms of "sufficient statistics." We compare welfare under mandate-based reform to welfare in a counterfactual world where individuals do not value ESHI. Relying on the Massachusetts reform, we find that jobs with ESHI pay $2812 less annually, somewhat less than the cost of ESHI to employers. Accordingly, the deadweight loss of mandate-based health reform was approximately 8 percent of its potential size. PMID:27037897

  2. Six direct methods for standardisation of 152Eu

    NASA Astrophysics Data System (ADS)

    Johansson, L.; Altzitzoglou, T.; Sibbens, G.; Denecke, B.; Reher, D. F. G.

    2003-08-01

    In the course of the past 40 years, IRMM has developed a large number of direct methods for the accurate standardisation of radionuclide solutions, all providing traceability to the SI unit. Six different measurement methods were employed to standardise a 152Eu solution in the frame of a BIPM key comparison: 4πβ(PPC)-γ-coincidence counting, using a modified version of the 'Funck' pressurised proportional counter (Ar-CH 4) for counting the electrons and low-energy photons, and a 15×15 cm NaI(Tl) well crystal for counting the γ-rays; 4πβ(PPC)-γ-sum counting using the same equipment as above; 4πβ-γ-coincidence counting, using a 2D shaped proportional counter (Kr-CH 4) sandwiched between two 7.5×7.5 cm 2 NaI(Tl) crystals; 4πγ counting, using a 15×15 cm 2 NaI(Tl) well crystal; 4πCsI(Tl) counting; Liquid scintillation counting (LSC) using the CIEMAT/NIST method. The methods will be described and compared, with emphasis on their strengths and weaknesses. In the case of 152Eu, we were able to achieve a standard deviation of the weighted mean of 0.14% among all methods, or 0.11% when excluding the LSC result.

  3. EuTEPC: measurements in gamma and neutron fields.

    PubMed

    Moro, D; Chiriotti, S

    2015-09-01

    The EuTEPC (European TEPC) is a novel spherical tissue-equivalent gas-proportional single-wire counter that has been designed and constructed at the National Laboratories of Legnaro of Italian Nuclear Physics Institute in collaboration with the University of Padova, the DLR (German Aerospace Centre) and Austrian Institute of Technology. Its peculiarity is the spherical A-150 cathode wall which is sub-divided in nine sectors. Each sector is properly and differently biased, in order to obtain a uniform electric field along the anode wire, for reaching a good isotropic response and energy resolution. The counter components can be easily replaced and reassembled including the anode wire. The counter could be used as a monitor area inside the International Space Station. This paper describes first microdosimetric measurements in (60)Co, (137)Cs and (241)Am-Be(α,n) gamma and neutron fields performed with the EuTEPC filled with pure propane gas. Measurements have been performed simulating sites sizes, ranging from 0.05 up to 0.25 mg cm(-2) in pure propane, which correspond from 0.7 up to 3.3 µm equivalent site sizes in propane-TE gas. Comparisons with some literature spectra are presented. PMID:25877529

  4. Polarized emission from KCl:Eu2+ single crystals

    NASA Astrophysics Data System (ADS)

    Kang, Jun-Gill; Sohn, Youngku; Nah, Min-Kook; Kim, Youn-Doo; Ogryzlo, Elmer A.

    2000-04-01

    The polarization emission spectrum and the angular dependence of polarization ratio of the blue emission from KCl:Eu2+ were investigated at 78.8 K. The polarized emission at 420 nm consisted of several components. The angular dependence of polarization ratio of each component is proportional to sin(2icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> ) or -cos(2icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> ), when the exciting light is polarized at icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> with respect to the z -axis for the [100]-[010] optical arrangement. The relaxed excited states (RESs) of Eu2+ responsible for the 420 nm emission are presented in terms of the adiabatic potential energy surface (APES), taking into account the Jahn-Teller effect (JTE) coupling to the Eg mode and the spin-orbit (SO) interaction. The charge-compensating cation vacancy (CCV, Vc - ) also causes an additive perturbation.

  5. {sup 151}Eu and {sup 121}Sb Moessbauer spectroscopy of EuSbSe{sub 3} and EuBiSe{sub 3}

    SciTech Connect

    Schappacher, Falko M.; Poettgen, Rainer Bang Jin, Geng; Albrecht-Schmitt, Thomas E.

    2007-11-15

    {sup 151}Eu and {sup 121}Sb Moessbauer spectroscopy of EuSbSe{sub 3} and EuBiSe{sub 3} were measured at different temperatures. The presence of divalent europium and trivalent antimony were confirmed. The largely negative values of the isomer shift in {sup 151}Eu spectrum show highly ionic bonding within these two compounds. Both of them show magnetic hyperfine field splitting at 4.2 K, which indicates a change in the orientation of the EFG principal axis with respect to the magnetic hyperfine field direction. EuSbSe{sub 3} has slightly smaller electron density at the antimony nuclei, compared to Sb{sub 2}Se{sub 3.} - Graphical abstract: Experimental and simulated {sup 121}Sb Moessbauer spectrum of EuSbSe{sub 3} at 77 K.

  6. Effect of Eu-citrate complex composition on its cementation

    SciTech Connect

    Lebedev, V.M.; Kornilov, A.S.; Yadovin, A.A.

    1995-03-01

    The dependence of Eu cementation by sodium amalgam in a semicountercurrent regime from citrate solutions on the Eu complex composition is studied. The purity of the {sup 153}Gd product from radioactive Eu can be increased during cementation by introducing correcting solutions of citric acid and stable Eu. The selected conditions are verified by processing irradiated targets. The content of radioactive Eu in the {sup 153}Gd product is reduced from 0.01 to 0.0005% with respect to {gamma}-activity.

  7. Synthesis and luminescence properties of ZnGa2O4 spinel doped with Co2+ and Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Duan, Xiulan; Yu, Fapeng; Wu, Yuanchun

    2012-11-01

    ZnGa2O4 nanopowders doped with Co2+ and Eu3+ ions, including dual doping, have been synthesized by citrate sol-gel method, and characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results show that ZnGa2O4 spinels were produced by calcining the gel above 500 °C, with the crystallite size of 16-30 nm in the temperature range of 500-900 °C. Co2+ ions are located at the tetrahedral sites of ZnGa2O4 spinel by replacing Zn2+, and Eu3+ ions are incorporated in the defect regions at the grain boundaries. The emission spectra of Eu-doped ZnGa2O4 nanopowders display an intense emission at 615 nm belonging to 5D0-7F2 transition of Eu3+ ions. With the introduction of Co into Eu-doped ZnGa2O4, the emission intensity at 615 nm decreases, while the luminescence at 680 nm due to tetrahedral Co2+ increases. The result indicates that the energy transfer occurred from Eu3+ to Co2+ ions. The energy transfer was also studied by the luminescence decay behavior. The emission of Co and Eu Co-doped ZnGa2O4 also changed with annealing temperature. The luminescence properties of the doped ZnGa2O4 nanopowders can be controlled by the variation of Co and Eu doping concentration and annealing temperature.

  8. In situ Gas Conditioning in Fuel Reforming for Hydrogen Generation

    SciTech Connect

    Bandi, A.; Specht, M.; Sichler, P.; Nicoloso, N.

    2002-09-20

    The production of hydrogen for fuel cell applications requires cost and energy efficient technologies. The Absorption Enhanced Reforming (AER), developed at ZSW with industrial partners, is aimed to simplify the process by using a high temperature in situ CO2 absorption. The in situ CO2 removal results in shifting the steam reforming reaction equilibrium towards increased hydrogen concentration (up to 95 vol%). The key part of the process is the high temperature CO2 absorbent. In this contribution results of Thermal Gravimetric Analysis (TGA) investigations on natural minerals, dolomites, silicates and synthetic absorbent materials in regard of their CO2 absorption capacity and absorption/desorption cyclic stability are presented and discussed. It has been found that the inert parts of the absorbent materials have a structure stabilizing effect, leading to an improved cyclic stability of the materials.

  9. The Rocky Road to Reform in Rochester.

    ERIC Educational Resources Information Center

    Koppich, Julia E.

    A profile of Rochester, New York, Public School District's educational reform efforts from 1987 to 1990 is offered in this case study. Following an overview of the city and its public schools, the impetus for educational reform is discussed, with attention given to the roles of the superintendent, teachers' union president, and school board.…

  10. Leading Mathematics Reform and the Lost Opportunity

    ERIC Educational Resources Information Center

    Lamb, Janeen

    2010-01-01

    Queensland's primary school teachers have experienced change in every Key Learning Area in the last few years. This avalanche of curriculum reform is set to continue as schools prepare for the imminent release of the Australian national curriculum. This article reports on one school's approach to dealing with this avalanche of curriculum reform.…

  11. Educational Reform: A Self-Scrutinizing Memoir.

    ERIC Educational Resources Information Center

    Sarason, Seymour B.

    In this book, the author candidly confronts errors he made of omission, commission, misplaced emphases, and watering down the depth and scope of his criticisms of the reform arena in his half-century involvement in educational reform. No other major figure in this arena has made public such a searching self-critique. Sharing his thoughts about the…

  12. Evaluating Multigrade School Reform in Latin America

    ERIC Educational Resources Information Center

    McEwan, Patrick J.

    2008-01-01

    This paper describes three multigrade school reforms in Latin America: (1) Colombia's "Escuela Nueva", (2) Guatemala's "Nueva Escuela Unitaria", and (3) Chile's MECE-Rural. Each reform endowed primary teachers and students with special training and instructional materials, and encouraged new kinds of instruction in rural classrooms, with the goal…

  13. Lessons in Reading Reform: Finding What Works

    ERIC Educational Resources Information Center

    Betts, Julian R.; Zau, Andrew C.; Koedel, Cory

    2010-01-01

    The San Diego Unified School District, the nation's eighth-largest, launched an ambitious program of literacy reforms in 2000 aimed at narrowing reading achievement gaps. Known as the Blueprint for Student Success, the program ran through 2005. The reforms succeeded in boosting the reading achievement of students who had been identified as lagging…

  14. Emerging Issues in Educational Reform in Japan.

    ERIC Educational Resources Information Center

    Wong, Kenneth K.

    2003-01-01

    Uses the demand-supply continuum to look at emerging reforms in the Japanese educational system. Data from fieldwork in major urban districts and their prefectures in Nagoya, Osaka, and Tokyo highlight demand-driven reform (higher education restructuring), integrated governance (mediating demand and supply at the K-12 levels), and ongoing…

  15. Long Term Impact on Reforming Classroom Practice.

    ERIC Educational Resources Information Center

    Williams, Marium T.

    This paper describes Morehead State University's support of the Kentucky Education Reform Act through mini-grants to public school teachers to help them implement state reform mandates and guidelines in the classroom through in-school action research projects. Morehead State University funded 18 mini-grants to 14 different schools in 11 different…

  16. After Access: Canadian Education and Copyright Reform

    ERIC Educational Resources Information Center

    Geist, Michael

    2006-01-01

    With the dramatic growth of the Internet in the 1990s, the Canadian government developed a well-regarded strategy for addressing the emerging issues posed by the "information highway." The strategy featured legal reforms to address privacy and e-commerce, administrative reforms for the government online initiative, and connectivity programs such…

  17. How Block Scheduling Reform Effects Classroom Practice

    ERIC Educational Resources Information Center

    Veal, William R.; Flinders, David J.

    2001-01-01

    Block scheduling has become an increasingly popular reform movement for schools, school districts, and principals to enact. Much of the decision making as to whether to implement some type of block scheduling has occurred without understanding the implications this type of reform has on teachers and their classroom practices. This paper reports on…

  18. Income Tax Reform and Agriculture: A Symposium.

    ERIC Educational Resources Information Center

    Economic Research Service (USDA), Washington, DC.

    Five papers are provided from a symposium organized to present several economic studies relating to income tax structure and reform in agriculture. "Toward an Optimal Income Tax Policy for Southern and U.S. Agriculture" (Harold F. Breimyer) is a structured argument for comprehensive tax reform that increases the equity of the income tax system…

  19. Reforming Administrator Preparation Programs. UCEA Monograph Series.

    ERIC Educational Resources Information Center

    Wendel, Frederick C., Ed.

    This publication contains four chapters that examine the reform of administrator preparation programs. In "The Reform Paradigm: Exploring the Fuzzy Logic of Educational Administration," William Ammentorp and Thomas Morgan develop a model based on linguistic algorithms to understand qualitative policy formation and decision making. In "Student…

  20. A fresh start for health reform?

    PubMed

    Kendall, D B

    1996-01-01

    Health reform isn't a popular subject in Washington these days, but problems of cost and access persist. The author, a senior health policy analyst for the Progressive Policy Institute, argues that in next year's debate of tax reform, a few modest changes could lead to a more effective and universal market for health care. PMID:10158552