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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. The EU sustainable energy policy indicators framework.

    PubMed

    Streimikiene, Dalia; Sivickas, Gintautas

    2008-11-01

    The article deals with indicators framework to monitor implementation of the main EU (European Union) directives and other policy documents targeting sustainable energy development. The main EU directives which have impact on sustainable energy development are directives promoting energy efficiency and use of renewable energy sources, directives implementing greenhouse gas mitigation and atmospheric pollution reduction policies and other policy documents and strategies targeting energy sector. Promotion of use of renewable energy sources and energy efficiency improvements are among priorities of EU energy policy because the use of renewable energy sources and energy efficiency improvements has positive impact on energy security and climate change mitigation. The framework of indicators can be developed to establish the main targets set by EU energy and environmental policies allowing to connect indicators via chain of mutual impacts and to define policies and measures necessary to achieve established targets based on assessment of their impact on the targeted indicators representing sustainable energy development aims. The article discusses the application of indicators framework for EU sustainable energy policy analysis and presents the case study of this policy tool application for Baltic States. The article also discusses the use of biomass in Baltic States and future considerations in this field.

  3. Policy challenges and reforms in small EU member state health systems: a narrative literature review.

    PubMed

    Azzopardi-Muscat, Natasha; Funk, Tjede; Buttigieg, Sandra C; Grech, Kenneth E; Brand, Helmut

    2016-12-01

    The EU directive on patients' rights and cross-border care is of particular interest to small states as it reinforces the concept of health system cooperation. An analysis of the challenges faced by small states, as well as a deep evaluation of their health system reform characteristics is timely and justified. This paper identifies areas in which EU level cooperation may bring added value to these countries' health systems. Literature search is based primarily on PUBMED and is limited to English-language papers published between January 2000 and September 2014. Results of 76 original research papers appearing in peer-reviewed journals are summarised in a literature map and narrative review. Primary care, health workforce and medicines emerge as the salient themes in the review. Lack of capacity and small market size are found to be the frequently encountered challenges in governance and delivery of services. These constraints appear to also impinge on the ability of small states to effectively implement health system reforms. The EU appears to play a marginal role in supporting small state health systems, albeit the stimulus for reform associated with EU accession. Small states face common health system challenges which could potentially be addressed through enhanced health system cooperation at EU level. The lessons learned from research on small states may be of relevance to health systems organized at regional level in larger European states. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

  4. 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.

  5. Energy transfer between Eu3+ ions in calcium diborate glasses

    NASA Astrophysics Data System (ADS)

    Lavín, V.; Martín, I. R.; Rodríguez-Mendoza, U. R.; Rodríguez, V. D.

    1999-11-01

    The evolution of the 5D0icons/Journals/Common/to" ALT="to" ALIGN="TOP"/> 7F0 emission of Eu3+ ions in calcium diborate glasses has been analysed using time resolved fluorescence line narrowing measurements in order to give a complete view of the energy transfer processes between these ions. At low concentration (2.5 mol% of Eu2O3) and exciting within the high energy side of the inhomogeneous 7F0icons/Journals/Common/to" ALT="to" ALIGN="TOP"/> 5D0 absorption band, the luminescence spectrum mainly consists of a narrow resonant peak that repeats the exciting profile, indicating that the migration processes between Eu3+ ions within the 5D0 level is not important. However, at higher concentrations (5 to 11.5 mol% of Eu2O3) the luminescence spectrum contains not only a narrow emission but also a broad band due to ions excited by energy transfer (background fluorescence), which for long times well reproduces the inhomogeneous profile. The temporal evolution of the narrow band fluorescence and the shape of the background fluorescence have been analysed using a previously proposed model. The purpose is to understand the dynamics involved in the energy transfer processes caused by the interaction between Eu3+ ions and the implications in their luminescence. A very good agreement with the experimental results is found taking into account an energy dependent quadrupole-quadrupole (S = 10) non-radiative energy transfer process assisted by a phonon from Eu3+ ions at high crystal field sites to ions at low crystal field sites. The temperature dependence of the energy transfer processes is analysed in the range from 13 to 60 K.

  6. EU ENERGY STAR Certified Uninterruptible Power Supplies

    EPA Pesticide Factsheets

    Certified models meet all ENERGY STAR requirements as listed in the Version 1.0 ENERGY STAR Program Requirements for Uninterruptible Power Supplies that are effective as of August 1, 2012. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=uninterruptible_power_supplies.pr_crit_uninterruptible_power_supplies

  7. 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

  8. Luminescence properties of dual valence Eu doped nano-crystalline BaF2 embedded glass-ceramics and observation of Eu2+ → Eu3+ energy transfer.

    PubMed

    Biswas, Kaushik; Sontakke, Atul D; Sen, R; Annapurna, K

    2012-03-01

    Europium doped glass-ceramics containing BaF(2) nano-crystals have been prepared by using the controlled crystallization of melt-quenched glasses. X-ray diffraction and transmission electron microscopy have confirmed the presence of cubic BaF(2) nano-crystalline phase in glass matrix in the ceramized samples. Incorporation of rare earth ions into the formed crystalline phase having low phonon energy of 346 cm(-1) has been demonstrated from the emission spectra of Eu(3+) ions showing the transitions from upper excitation states (5)D(J) (J = 1, 2, and 3) to ground states for the glass-ceramics samples. The presence of divalent europium ions in glass and glass-ceramics samples is confirmed from the dominant blue emission corresponding to its 5d-4f transition under an excitation of 300 nm. Increase in the reduction of trivalent europium (Eu(3+)) ions to divalent (Eu(2+)) with the extent of ceramization is explained by charge compensation model based on substitution defect mechanisms. Further, the phenomenon of energy transfer from Eu(2+) to Eu(3+) ion by radiative trapping or re-absorption is evidenced which increases with the degree of ceramization. For the first time, the reduction of Eu(3+) to Eu(2+) under normal air atmospheric condition has been observed in a BaF(2) containing oxyfluoride glass-ceramics system.

  9. Coexistence phenomenon of Ce(3+)-Ce(4+) and Eu(2+)-Eu(3+) in Ce/Eu co-doped LiBaB9O15 phosphor: luminescence and energy transfer.

    PubMed

    Li, Ting; Li, Panlai; Wang, Zhijun; Xu, Shuchao; Bai, Qiongyu; Yang, Zhiping

    2017-02-01

    Ce/Eu-doped LiBaB9O15 (LBB) samples were prepared via conventional high temperature solid state reactions. The XRD patterns, crystal structures, luminescence properties, and decay times were investigated systematically. Ce(3+) ions exist in LBB:xCe(3+) that were synthesized in a reducing atmosphere and in an air atmosphere. However, we observed Eu(2+) ions in LBB:yEu(2+) in a reducing atmosphere and Eu(3+) ions in LBB:zEu(3+) in an air atmosphere. LBB:0.05Ce(3+),yEu(2+) phosphors synthesized in a reducing atmosphere only possess Ce(3+) and Eu(2+) and exhibit a broad excitation band ranging from 350 to 425 nm. A reduction phenomenon of Eu(3+) → Eu(2+) and coexistence of Ce(4+), Ce(3+), Eu(2+) and Eu(3+) were observed when LBB:0.05Ce,wEu phosphors were synthesized in an air atmosphere. There are three processes in LBB:0.05Ce,wEu, i.e., energy transfers from Ce(3+) to Eu(2+) and from Eu(2+) to Eu(3+), and metal-metal charge transfer (MMCT) between Ce(3+) and Eu(3+). Moreover, the MMCT process is dominant in LBB:0.05Ce,wEu due to less efficient energy transfer from Ce(3+) to Eu(2+). Moreover, the CIE coordinates of LBB:0.05Ce,wEu vary systematically from light blue (0.313, 0.129) to red (0.589, 0.315) for LBB:0.05Ce(3+),wEu synthesized in air with the changes in Eu ion concentration. Thus, we can control the color by controlling the synthesis atmospheres.

  10. Does the EU sugar policy reform increase added sugar consumption? An empirical evidence on the soft drink market.

    PubMed

    Bonnet, Céline; Requillart, Vincent

    2011-09-01

    Whereas National Health authorities recommend a decrease in the consumption of 'added' sugar, a reform on the sugar market will lead to a 36% decrease of the sugar price in the EU. Using French data on soft drinks purchases, this paper investigates the anticipated impact of this reform on the consumption of sugar-sweetened beverages. The reform of the EU sugar policy leads to a decrease in regular soft drink prices by 3% and varies across brands. To assess substitution within this food category, we use a random-coefficients logit model that takes into account a large number of differentiated products and heterogeneity in consumers' behavior. Results suggest that price changes would lead to an increase in market shares of regular products by 7.5% and to substitutions between brands to the benefit of products with the highest sugar content. On the whole, it would raise consumption of regular soft drinks by more than 1 litre per person per year and consumption of added sugar by 124 g per person per year, this increase being larger in households composed of overweight and obese individuals. Copyright © 2011 John Wiley & Sons, Ltd.

  11. 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…

  12. 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…

  13. Intelligence Reform in Albania: Its Relation to Democratization and Integration into the EU and NATO

    DTIC Science & Technology

    2008-03-01

    Integration into EU and NATO 6. AUTHOR(S) Eduart Bala 5 . FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate...50 4. The Special Telecommunications Service (STS) .............................50 5 . The Defense General Information Agency (DGIA...68 5 . Press and Civil Society.......................................................................68 6. Intelligence

  14. Seminar on EU and energy held in Kohtu, Tallinn on June 13, 1997

    SciTech Connect

    1997-06-13

    This seminar addresses the energy policy of the European Union. The topics of the seminar include the energy strategy for Estonia; energy policy for the European Union; EU and Energy Markets; EC`s Climate Strategy; and Promotion of Energy Co-operation between Estonia and Finland.

  15. Energy transfer (In3+ → Eu3+) based Polyvinyl Alcohol polymer composites for bright red luminescence

    NASA Astrophysics Data System (ADS)

    Kumar, K. Naveen; Vijayalakshmi, L.; Kim, Jong Su; Shim, Jaesool; Cho, Migyung; Kang, Misook; Gupta, Bipin Kumar

    2017-08-01

    A prominent sensitization effect of In3+ ions is observed in In3++Eu3+: PVA polymer composites under UV excitation. Consequently, it enhances the red emission performance of Eu3+ ions in PVA system. We have successfully synthesized Eu3+: PVA, In3+: PVA and In3++Eu3+: PVA polymer films by traditional solution casting method. The structural and ion-polymer interaction studies have been analyzed from XRD and FTIR spectral profiles. Eu3+ doped PVA polymer composites are exhibited a red emission at 619 nm (5D0→7F2) under 396 nm (7F0→5L6) of excitation. Upon co-doping with In3+ ions in different concentrations to the Eu3+: PVA polymer film, it exhibits predominant red emission than singly doped Eu3+: PVA under 396 nm of excitation due to energy migration from In3+ to Eu3+. Successful emission photons of In3+ ions are collectively absorbed by the Eu3+ ions which lead the improvement of red emission. Optimized sensitization concentration of the In3+ ions has been found to be 0.01 wt%. Possible energy migration phenomenon is elucidated by several fluorescent dynamics. The energy transfer process is substantiated by lifetime decay analysis and overlapped spectral studies. The Commission International de I-Eclairage chromaticity coordinates were calculated. The quantum efficiencies of the Eu3+ ions and In3+ ions in singly doped and co-doped polymer systems have been evaluated. From these results, these co-doped In3++Eu3+: PVA composite polymer films might be proposed as encouraging candidates for bright red fluorescent materials for several photonic applications.

  16. 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.

  17. Academic Governance and Academic Reform: Legitimacy and Energy.

    ERIC Educational Resources Information Center

    Peter, Kenneth B.; Bain, Linda L.

    1998-01-01

    A thorough review and revision of curriculum at San Jose State University (California) illustrates that the modern university can achieve major internal academic reforms when two important conditions are met: legitimacy and energy. These two concepts are defined and practical illustrations are drawn from the institution's recent experience in…

  18. Mexico`s economic reform: Energy and the Constitution

    SciTech Connect

    Rubio, L.

    1993-12-31

    Oil is a fundamental component of nationhood in Mexico. The 1938 expropriation of oil resources concluded a process of internal political consolidation and thus became the most important symbol of nationalism. Mexico has been undergoing a process of economic reform that has altered the country`s economic structure and has subjected it to international competition. Oil in particular and energy in general have been left untouched. There is recognition that without an equal reform of the energy industry, the potential for success will be significantly limited. While the Constitution allows private investment in the industry--with the exception of the resource properties themselves--the Regulatory Law bans any private participation. Because of its political sensitivity, however, amending the law in order to reform the oil industry will necessitate a domestic initiative rather than foreign pressure. In this perspective, NAFTA served to slow and postpone the reform of the industry, rather than the opposite. Once NAFTA is well in place, the industry will have to face competition.

  19. Tunable luminescence properties and energy transfer in LaAl₁₁O₁₈: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 LaAl11O18 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 LaAl11O18: Eu, show the enhanced green emission at 545 nm associated with (5)D(4)-(7)F(5) 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 LaAl11O18 phosphor will have potential application for UV convertible white light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.

  20. 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.

  1. Luminescent properties and energy level structure of CaZnOS:Eu2+

    NASA Astrophysics Data System (ADS)

    Budde, B.; Luo, H.; Dorenbos, P.; van der Kolk, E.

    2017-07-01

    In this work it is shown that CaZnOS:Eu2+ has no Eu2+ emission even at low temperature. The observed and earlier reported red emission originates from a CaS:Eu2+ impurity phase. By means of washing the as-prepared samples with diluted nitride acid, we were able to remove the CaS impurity phase and study the Eu2+ emission in the pure CaZnOS phase. A clear relation was found between the red emission intensity, the CaS XRD line intensities and the nitric acid solution washing time, with zero intensity after prolonged washing. A so-called VRBE (vacuum referred binding energy)-diagram was constructed showing the energy of the 4fn and 4fn-15d1 states of the divalent and trivalent rare earth ions as dopants in CaZnOS with respect to the vacuum energy. This diagram shows that the 5d-levels of Eu2+ are located in the conduction band, which explains the absence of 5d→4f emission. By comparing the VRBE diagram with diagrams of other related compounds like CaO, CaS, ZnO and ZnS it becomes clear that the Eu2+ luminescence quenching is caused by a low lying conduction band, typical for Zn-based compounds.

  2. 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.

  3. 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.

  4. Luminescence properties and energy transfer of Tb3+-Eu3+ co-doped Sr3B2O6 phosphors

    NASA Astrophysics Data System (ADS)

    Tuyen, Ho Van; Nguyen, Manh Son

    2017-06-01

    A series of single-composition phosphors Sr3B2O6: Tb3+, Eu3+have been prepared via a combustion method. The structural and luminescent properties of phosphor are investigated in detail. Under ultraviolet radiation excitation, Sr3B2O6: Tb3+, Eu3+ phosphors show the characteristic f-f transitions of both Eu3+ and Tb3+ and give a bright yellow emission. The investigations on photoluminescence and lifetime of Eu3+ show that there are two sites of luminescence center of Eu3+ in host matrix. The energy transfer from Tb3+ ion to Eu3+ ion are observed and the mechanism of energy transfer is dipole-quadrupole interaction.

  5. 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.

  6. Optimized Energy Transfer from Electron-hole pairs to Eu ions in GaN

    NASA Astrophysics Data System (ADS)

    Wei, Ruoqiao; Hernandez, Natalie; Mitchell, Brandon; Fujiwara, Yasufumi; Dierolf, Volkmar

    Europium doped Gallium Nitride (GaN:Eu) has demonstrated potential for the red-emitting active layer in nitride-based light emitting diodes. Under above band gap excitation, the red emission was shown to increase due to the optimization of crystal growth conditions. This suggests that excitation efficiency had been improved, which would imply that the energy transfer from electron-hole pairs to Eu ions occurred on a faster time-scale. To test this assumption, we performed time-resolved spectroscopy measurements, under ps-scale time resolution, on samples with a variety of co-dopants and growth conditions. Results show that the energy is transferred on a time scale faster than ns and the excitation efficiency is influenced by the various growth parameters and co-dopants.

  7. Synthesis, energy transfer and tunable emission properties of SrSb2O6:Eu3 +, Bi3 + phosphor

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Host SrSb2O6, SrSb2O6:Bi3 +, SrSb2O6:Eu3 +, and SrSb2O6:Eu3 +, Bi3 + phosphors are synthesized by solid state reaction method in air. Host SrSb2O6 with excitation 254 nm shows weak green-yellow emission in the range of 320-780 nm due to Sb5 + → O2- transition. SrSb2O6:Bi3 + phosphor with excitation 365 nm emits green light within the range 400-650 nm owing to the 3P1 → 1S0 transition of Bi3 + ion. SrSb2O6:Eu3 + phosphor with excitation 254 nm exhibits a systematically varied hue from green to orange-red light by increasing Eu3 + concentration from 0 to 7 mol%, and that with excitation 394 nm only shows orange-red light. The optimal Eu3 + concentration is 4 mol% in SrSb2O6:Eu3 + phosphor. SrSb2O6:Eu3 +, Bi3 + phosphor with excitation 254 and 394 nm emits orange-red light. Emission intensity of SrSb2O6:Eu3 + phosphor may be enhanced > 2 times by co-doping Bi3 + ion because of the fluxing agent and energy transfer roles of Bi3 + ion in SrSb2O6:Eu3 +, Bi3 + phosphor. The luminous mechanism of SrSb2O6:Eu3 +, Bi3 + phosphor is analyzed and explained by the simplified energy level diagrams of Sb2O62 - group, Bi3 + and Eu3 + ions, and energy transfer processes between them.

  8. 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

    2016-12-05

    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.

  9. Enhanced Pr3+ photoluminescence by energy transfer in SrF2 : Eu2+, Pr3+ phosphor

    NASA Astrophysics Data System (ADS)

    Yagoub, M. Y. A.; Swart, H. C.; Bergman, P.; Coetsee, E.

    2016-02-01

    Efficient energy transfer was demonstrated in the SrF2 : Eu2+, Pr3+ phosphor synthesized by the co-precipitation method. Results obtained with X-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray spectroscopy (XPS), photoluminescence (PL) and decay curves proposed the UV-Vis energy transfer process. The energy transfer process between the Eu2+ and Pr3+ ions in SrF2 was investigated to evaluate the potential of the Eu2+ ion as a sensitizer for the Pr3+ ion. The results proposed that Eu2+ could be a good sensitizer for absorbing the UV photons and efficiently enhancing the Pr3+ emission intensity. The energy transfer process was effective until concentration quenching for the Pr3+ ions occurred. The concentration quenching was attributed to cross-relaxation between the Pr3+ ions.

  10. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Roadmap of retail electricity market reform in China: assisting in mitigating wind energy curtailment

    NASA Astrophysics Data System (ADS)

    Yu, Dezhao; Qiu, Huadong; Yuan, Xiang; Li, Yuan; Shao, Changzheng; Lin, You; Ding, Yi

    2017-01-01

    Among the renewable energies, wind energy has gained the rapidest development in China. Moreover wind power generation has been penetrated into power system in a large scale. However, the high level wind curtailment also indicates a low efficiency of wind energy utilization over the last decade in China. One of the primary constraints on the utilization of wind energy is the lack of an electricity market, in which renewable energies can compete equally with traditional fossil fuel generation. Thus the new round electric power industry reform is essential in China. The reform involves implementing new pricing mechanism, introducing retail-side competition, promoting the consumption of renewable energy. The new round reform can be a promising solution for promoting the development and consumption of wind energy generation in China. Based on proposed reform policies of electric power industry, this paper suggests a roadmap for retail electricity market reform of China, which consists of three stages. Barriers to the efficient utilization of wind energy are also analysed. Finally, this paper introduces several efficient measures for mitigating wind curtailment in each stage of reform.

  12. 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…

  13. High energy sideband on the magnetic polaron related luminescence in EuTe

    NASA Astrophysics Data System (ADS)

    Heredia, E.; Motisuke, P.; de Oliveira Rappl, P. H.; Brasil, M. J. S. P.; Iikawa, F.

    2012-08-01

    We investigated the near band gap luminescence of EuTe thin films grown by molecular beam epitaxy, using excitation intensities up to 2 × 105 W/cm2. Besides the previously reported high energy emissions MX1 and MX2, we observed an additional emission band at higher energies. This higher-energy band is only detected when high excitation intensities, over 2 kW/cm2, are used. With increasing externally applied magnetic field, this additional emission band shifts to lower energies at a rate even higher than the MX1. The two bands, however, have different temperature dependences and decay times, suggesting that distinct electronic states are involved in their emission.

  14. 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.

  15. Energy from waste in Europe: an analysis and comparison of the EU 27.

    PubMed

    Sommer, Manuel; Ragossnig, Arne

    2011-10-01

    This article focuses on analysing the development of waste-generated energy in the countries of the European Union (EU 27). Besides elaborating the relevant legal and political framework in the waste and energy sector as well as climate protection, the results from correlation analyses based on the databases of the energy statistics from Eurostat are discussed. The share of energy from waste is correlated with macro-economic, waste- and energy-sector-related data, which have been defined as potentially relevant for energy recovery from waste in the countries of the European Union. The results show that a single factor influencing the extent of waste-generated energy could not be isolated as it is being influenced not only by the state of economic development and the state of development of waste management systems in the respective countries but also by energy-sector-related factors and the individual priority settings in those countries. Nevertheless the main driving force for an increase in the utilization of waste for energy generation can be seen in the legal and political framework of the European Union leading to the consequence that market conditions influence the realization of waste management infrastructure for waste-generated energy.

  16. 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.

  17. 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

  18. 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.

  19. Upconversion emissions from high-energy states of Eu3+ sensitized by Yb3+ and Ho3+ in β-NaYF4 microcrystals under 980 nm excitation.

    PubMed

    Wang, Lili; Liu, Zhenyu; Chen, Zhe; Zhao, Dan; Qin, Guanshi; Qin, Weiping

    2011-12-05

    Under 980 nm excitation, multiple ultraviolet and visible upconversion luminescence from Ho3+ and Eu3+ ions were observed in Yb3+/Ho3+/Eu3+ tri-doped NaYF4 microcrystals (MCs). The high-energy states (5H3-7, 5L6, 5D3 and 5D2) of Eu3+ ions could be efficiently populated by two-step energy transfer (ET) processes of Yb → Ho → Eu. Four-, three-, two-photon UC processes of Eu3+ ions were confirmed by the dependence of 5H3-7, 5L6 and 5D0 levels emission intensities on the pumping power.

  20. Energy Bands and Thermoelectricity of Filled Skutterudite EuRu4As_{12}

    NASA Astrophysics Data System (ADS)

    Shankar, A.; Rai, D. P.; Sandeep; Khenata, R.; Thapa, R. K.; Mandal, P. K.

    2016-11-01

    Density functional theory-based calculations of the elastic and electronic properties with magnetic moments of the filled skutterudite EuRu4As_{12} have been performed in its ferromagnetic ground state. The full-potential linearized augmented plane wave (FP-LAPW) method has been used for the study presented here. The numerical values of the elastic parameters are estimated within the framework of the Voigt-Reuss-Hill approximations. The energy band structure calculation performed near the Fermi energy level shows the metallic nature of the material with a high value of Seebeck coefficient ( S). The presence of an exchange splitting of Eu-4 f states suggests their appreciable contribution toward the magnetic behavior. The analysis of the thermal transport properties confirms the result obtained from the electronic structure calculation with Seebeck coefficient of 118 μ{V/K} and the figure of merit ( ZT) value of 0.51, at room temperature. The estimated values of S and ZT indicate the possibility of the thermoelectric applications of the sample material.

  1. Mitigation of CO2 emissions from the EU-15 building stock: beyond the EU Directive on the Energy Performance of Buildings.

    PubMed

    Petersdorff, Carsten; Boermans, Thomas; Harnisch, Jochen

    2006-09-01

    GOAL SCOPE AND BACKGROUND: The European Directive on Energy Performance of Buildings which came into force 16 December 2002 will be implemented in the legislation of Member States by 4 January 2006. In addition to the aim of improving the overall energy efficiency of new buildings, large existing buildings will become a target for improvement, as soon as they undergo significant renovation. The building sector is responsible for about 40% of Europe's total end energy consumption and hence this Directive is an important step for the European Union in order that it should reach the level of saving required by the Kyoto Agreement. In this the EU is committed to reduce CO2 emissions relative to the base year of 1990 by 8 per cent, by 2010. But what will be the impact of the new Directive, how large could be the impacts of extending the obligation for energy efficiency retrofitting towards smaller buildings? Can improvement of the insulation offset or reduce the growing energy consumption from the increasing installation of cooling installations? EURIMA, the European Insulation Manufacturers Association and EuroACE, the European Alliance of Companies for Energy Efficiency in Buildings, asked Ecofys to address these questions. The effect of the EPB Directive on the emissions associated with the heating energy consumption of the total EU 15 building stock has been examined in a model calculation, using the Built Environment Analysis Model (BEAM), which was developed by Ecofys to investigate energy saving measures in the building stock. The great complexity of the EU-15 building stock had to be simplified by examining five standard buildings with eight insulation standards, which are assigned to building age and renovation status. Furthermore, three climatic regions (cold, moderate, warm) were distinguished for the calculation of the heating energy demand. This gave a basic 210 building types for which the heating energy demand and CO2 emissions from heating were

  2. Luminescence Spectra of YGG:RE3+, Bi3+ (RE = Eu and Tb) and Energy Transfer from Bi3+ to RE3+

    NASA Astrophysics Data System (ADS)

    Zhu, Nan-Fei; Li, Yong-Xiang; Yu, Xiao-Feng

    2008-02-01

    We investigate the luminescence properties of Bi3+ and RE3+ (RE = Tb or Eu) in a Y3Ga5O12 (YGG) host system. The additional doping of Bi3+ can enhance the luminescence of Tb3+ or Eu3+ in this host. Energy transfer from Bi3+ to Tb3+ and Eu3+ is observed and the mechanism of energy transfer is investigated. Mechanism of energy transfer can be explained as electric multipole interaction since the Bi3+ emission band and Tb3+ or Eu3+ excitation band overlaps and the Bi3+ emission intensity decreases while the intensity of Tb3+ or Eu3+ increases with the increase of Tb3+ or Eu3+ concentration. Therefore, Bi3+ ion is a kind of efficient sensitizer to the Tb3+ and Eu3+ activators in the Y3Ga5O12 host.

  3. Luminescence and energy transfer mechanism in Eu3+/Tb3+-co-doped ZrO2 nanocrystal rods

    NASA Astrophysics Data System (ADS)

    Ahemen, I.; Dejene, F. B.

    2017-01-01

    Nanocrystal rods of Eu3+/Tb3+-co-doped ZrO2 were synthesized using a simple chemical precipitation technique. Both ions were successfully doped into the Zr4+ ion site in a mixed structure containing both monoclinic and tetragonal phases. The Eu3+ or Tb3+ singly doped zirconia produced red and green luminescence which are characteristics of Eu3+ and Tb3+ ions, respectively. The co-doped zirconia samples produced blue emission from defect states transitions in the host ZrO2, red and green luminescence from dopant ions giving cool to warm white light emissions. The phosphors were efficiently excited by ultraviolet and near-ultraviolet/blue radiations giving white and red light, respectively. The decay lifetime was found to increase with increasing donor ion concentration contrary to conventional observations reported by previous researchers. Weak quadrupole-quatdrupole multipolar process was responsible for energy transfer from Tb3+ (donor) ion to Eu3+ ion. No energy back-transfer from Eu3+ to Tb3+ ion was observed from the excitation spectra. Temperature-dependent photoluminescence shows the presence of defects at low temperature, but these defects vanished at room temperature and beyond. The Eu3+/Tb3+-co-doped ZrO2 nanocrystal rod is a potential phosphor for white light application using UV as an excitation source. Thermoluminescence measurements show that the inclusion of Tb3+ ion increases trap depths in the host zirconia.

  4. 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.

  5. 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.

  6. Vacuum Referred Binding Energy (VRBE)-Guided Design of Orange Persistent Ca3Si2O7:Eu(2+) Phosphors.

    PubMed

    Ueda, Jumpei; Maki, Ryomei; Tanabe, Setsuhisa

    2017-09-05

    Orange persistent phosphors of Ca3Si2O7 (CSO) doped with Eu(2+) were strategically developed by codoping Sm(3+) or Tm(3+). First, a vacuum referred binding energy, VRBE, diagram of Ca3Si2O7 (CSO) was constructed from the measured spectroscopic data. By the zigzag curve of the divalent lanthanide ions in the VRBE diagram, Sm(3+) and Tm(3+) ions were predicted to be a suitable electron trap for the persistent luminescence. The initial persistent luminance of CSO:Eu(2+)-Sm(3+) and CSO:Eu(2+)-Tm(3+) was found to be 290 times and 9300 times stronger, respectively, compared with CSO:Eu(2+). By optimizing Eu(2+) and Tm(3+) concentrations, the persistent luminescence duration on 0.32 mcd/m(2) reached approximately 50 min in CSO:Eu(2+)-Tm(3+). From the VRBE diagram and the persistent luminescence properties, we discuss the persistent mechanism including the charging process, detrapping process, and electron trapping centers.

  7. Color-tunable electroluminescence from Eu-doped TiO(2)/p(+)-Si heterostructured devices: engineering of energy transfer.

    PubMed

    Zhu, Chen; Lv, Chunyan; Wang, Canxing; Sha, Yiping; Li, Dongsheng; Ma, Xiangyang; Yang, Deren

    2015-02-09

    We report on color-tunable electroluminescence (EL) from TiO(2):Eu/p(+)-Si heterostructured devices using different TiO(2):Eu films in terms of Eu content and annealing temperature. It is found that the Eu-related emissions are activated by the energy transferred from TiO(2) host via oxygen vacancies, at the price of weakened oxygen-vacancy-related emissions. Both the higher Eu content and the higher annealing temperature for TiO(2):Eu films facilitate the aforementioned energy transfer. In this context, the dominant EL from the TiO(2):Eu/p(+)-Si heterostructured devices can be transformed from oxygen-vacancy-related emissions into Eu-related emissions with increasing Eu-content and annealing temperature for TiO(2):Eu films, exhibiting different colors of emanated light. We believe that this work sheds light on developing silicon-based red emitters using the Eu-doped oxide semiconductor films.

  8. Business Pattern of Distributed Energy in Electric Power System Reformation

    NASA Astrophysics Data System (ADS)

    Liang, YUE; Zhuochu, LIU; Jun, LI; Siwei, LI

    2017-05-01

    Under the trend of the electric power system revolution, the operation mode of micro power grid that including distributed power will be more diversified. User’s demand response and different strategies on electricity all have great influence on the operation of distributed power grid. This paper will not only research sensitive factors of micro power grid operation, but also analyze and calculate the cost and benefit of micro power grid operation upon different types. Then it will build a tech-economic calculation model, which applies to different types of micro power grid under the reformation of electric power system.

  9. Energy transfer and color tunable emission in Tb(3+),Eu(3+) co-doped Sr3LaNa(PO4)3F phosphors.

    PubMed

    Li, Shuo; Guo, Ning; Liang, Qimeng; Ding, Yu; Zhou, Huitao; Ouyang, Ruizhuo; Lü, Wei

    2017-09-18

    A group of color tunable Sr3LaNa(PO4)3F:Tb(3+),Eu(3+) phosphors were prepared by conventional high temperature solid state method. The phase structures, luminescence properties, fluorescence lifetimes and energy transfer were investigated in detail. Under 369nm excitation, owing to efficient energy transfer of Tb(3+)→Eu(3+), the emission spectra both have green emission of Tb(3+) and red emission of Eu(3+). An efficient energy transfer occur in Tb(3+), Eu(3+) co-doped Sr3LaNa(PO4)3F phosphors. The most possible mechanism of energy transfer is dipole-dipole interaction by Dexter's theoretical model. The energy transfer of Tb(3+) and Eu(3+) was confirmed by the variations of emission and excitation spectra and Tb(3+)/Eu(3+) decay lifetimes in Sr3LaNa(PO4)3F:Tb(3+),Eu(3+). The color tone can tuned from yellowish-green through yellow and eventually to reddish-orange with fixed Tb(3+) content by changing Eu(3+) concentrations. The results show that the prepared Tb(3+), Eu(3+) co-doped color tunable Sr3LaNa(PO4)3F phosphor can be used for white LED. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. 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.

  11. Tunable luminescence of the full-color-emitting LiGd5P2O13:Bi3+,Eu3+ phosphor based on energy transfers

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Qiao, Jianwei; Liu, Yongfu; Huang, Ping; Shi, Qiufeng; Tian, Yue; Cui, Cai'e.; Luo, Zhaohua

    2017-05-01

    A series of Bi3+ and/or Eu3+ doped LiGd5P2O13 (LGPO) were synthesized via a solid state reaction. In the LiGd5P2O13 lattice, Bi3+ shows a broad bluish-green emission around 500 nm and Eu3+ exhibits typical f-f red emissions. Based on the Bi3+ → Eu3+ energy transfers, the luminescence colors can be tuned from bluish-green to orange by altering the Bi3+/Eu3+ ratio. Under the 290 nm excitation, the sample with optimal composition of LGPO:0.1Bi3+,0.01Eu3+ exhibits a white light emission with a CRI of 82 and a CCT of 4250 K. The energy transfer mechanism from Bi3+ to Eu3+ in the LiGd5P2O13 host was ascribed to the dipole-dipole interaction.

  12. Energy Reform for West Africa in Climate Change Crisis Era

    NASA Astrophysics Data System (ADS)

    Nwokocha, C.; Kasei, R.

    2009-04-01

    UNFCCC reports indicate that those who are least responsible for climate change are also the most vulnerable to its projected impacts. In no place is this more evident than in Sub-Saharan Africa, where greenhouse gas (GHG) emissions are negligible from a global scale. In Africa, energy demands could be the major factor that may lead to the increase of its emissions in the very near future. Forests are being lost for domestic energy, Oil produced energy increases carbon foot prints and Hydropower is unreliable due to uncertainties in rainfall patterns. By 2004, the energy consumption mix of West Africa was dominated by oil (58%) followed by natural gas (38%) and hydroelectric (8%) with coal and other energy forms not part of the mix. (Energy Information Administration, 2007). Rainfall and Global radiation using the Armstrong method was analyzed for sites in Nigeria and Ghana. A cost-benefit of the energy productions is presented.

  13. Solid state synthesis, luminescent properties and energy transfer from Eu2+ to Mn2+ in red phosphor BaMg2Si2O7:Eu2+,Mn2+

    NASA Astrophysics Data System (ADS)

    Xiao, Weiqin; Lei, Fang; Yin, Luqiao; Shi, Ying; Xie, Jianjun; Zhang, Lei

    2017-10-01

    A series of red phosphors Ba1-yMg2-xSi2O7: xMn2+,yEu2+ have been synthesized by solid-state reaction at 1200 °C for 4 h under H2 atmosphere. The crystal structure and photoluminescence properties have been measured and analyzed. Under excitation of 342 nm, Eu2+ doped Ba1-yMg2Si2O7 (y = 0.05-0.06) shows violet emission at 400 nm, which is due to the 4f-5d transition of Eu2+, while Mn2+ doped BaMg2-xSi2O7 (x = 0.02-0.40) shows weak reddish emission with a broad band centered at around 640 nm, which is caused by the 4T1(4G) -6A1(6S) transitions of Mn2+. When Eu2+ and Mn2+ were co-doped, excellent red emission is shown under the n-UV excitation. Eu2+ and Mn2+ co-doped BaMg2Si2O7 phosphor shows two intense emission bands with the peak at 400 nm and 660 nm, respectively. The broad emission band for Eu2+ overlaps with the excitation peaks of Mn2+ in the range of 400-450 nm, which shows that the emission of Mn2+ is dominantly ascribed to the persistent energy transfer from Eu2+. By changing the ratio of Eu2+/Mn2+, the emission color can be tuned from violet to red. When the doping content is fixed at 0.16 for Mn2+ and 0.32 for Eu2+, the CIE of the phosphor is (0.495,0.315). Eu2+ and Mn2+ co-doped BaMg2Si2O7 phosphors may have potential application for near-UV light-emitting diodes.

  14. 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.

  15. Photophysical and energy transfer processes in Ce3+ co-doped ZrO2: Eu3+ nanorods

    NASA Astrophysics Data System (ADS)

    Ahemen, I.; Dejene, F. B.

    2017-02-01

    Cerium (III) ion co-doped ZrO2: Eu3+ nanorods at varying Ce3+ ion concentrations were synthesized by a simple chemical dehydration route. Their structural, morphological and optical properties were investigated. Structural studies revealed a tetragonal phase with CeO2 phase grafted onto its surface. Field emission scanning electron microscopy images show nanorods of different dimensions. Diffraction peaks shifted towards smaller angles indicating the incorporation of the rare earth ions. Both Ce3+ (donor) and Eu3+ (activator) emission peaks were obtained when the samples were excited via the Ce3+ excitation band indicating energy transfer from the donor to activator. The process of energy transfer is both multipolar and exchange interactions. However, no significant enhancement of the activator's emission intensity, because concentration quenching process dominated the energy transfer process. The internal quantum efficiency, though low (20-25%), increased with increasing Ce3+ concentration.

  16. 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.

  17. Energy transfer in Sr2MgSi2O7:Eu2+ phosphors in nano scale and their application to solid state lighting with excellent color rendering.

    PubMed

    Kwon, Ki Hyuk; Im, Won Bin; Jeon, Duk Young

    2013-06-01

    On the basis of structural information of its host material which shows excellent stability and absorption efficiency in ultra-violet (UV) region, a blue-emitting Sr2MgSi2O7:Eu2+ (SMS:Eu2+) phosphor was synthesized, and its photoluminescence (PL) performance was systematically optimized. In order to enhance its PL properties, Ce3+ was added as a sensitizer based on the energy transfer from the absorption energy of Ce3+ to Eu2+. It was due to the spectral overlap between the photoluminescence excitation spectrum of Ce3+ and the PL spectrum of Eu2+. Moreover, the energy transfer rate from Ce3+ to Eu2+ is generally faster than the emission rate of Ce3+ in the dipole-dipole interaction. Depending upon the amount of Ca2+ substituted into Sr site, their maximum wavelength was varied from -460 to -540 nm in terms of the crystal field effect confirmed by the structural analysis via Rietveld refinement method. Finally, the optimized blue-emitting SMS:Eu2+ and Ca(2+)-substituted yellowish green-emitting SMS:Eu2+ phosphors were applied with Eu(2+)-sensitized red-emitting Ca3Mg3(PO4)4:Mn2+ phosphor introduced in our previous research to UV light emitting diode (LED)-pumped white LEDs. The fabricated white LEDs showed a natural white light with the color coordinate of (0.3298, 0.3280) and the excellent color rendering index of 94.

  18. Downshifting by energy transfer in Eu3+/Yb3+ codoped Ba4La6(SiO4)6O glass ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, W. J.; Li, X. B.; Wu, L. J.; Yu, Y. Y.; Wang, X. Z.; Liu, S. Q.; Wang, Z.; Wang, W. C.; Liu, Y.

    2017-03-01

    We report on an efficient near-infrared downshifting in Eu3+/Yb3+ codoped glass ceramics containing Ba4La6(SiO4)6O crystals. The structural and luminescence properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), static and dynamic photoemission and excitation spectroscopy. After crystallization, the doping ions are found to be selectively incorporated into the precipitated oxyapatite crystals on La3+ sites, contributing to the remarkably enhanced visible emission of Eu3+ under 394 nm excitation. The Eu3+/Yb3+ codoped glass ceramics additionally exhibits efficient near-infrared luminescence of Yb3+ around 1000 nm upon photon excitation of Eu3+ within the 300-550 nm range. The reduced visible emission and decay time of 5D0 state with Yb3+ codoping further confirm the energy transfer from Eu3+ to Yb3+, which is promoted due to the shortened distance between Eu3+ and Yb3+ within crystals. The maximum energy transfer efficiency is evaluated to be 61%. It is revealed that energy transfer process occurs predominantly through the cross relaxation of Eu3+(5D0) + Yb3+(2F7/2) → Eu3+(7F6) + Yb3+(7F5/2).

  19. Potential color tunable Sr3LaNa(PO4)3F:Eu(2+)/Tb(3+)/Mn(2+) phosphor induced by Eu(2+) → Tb(3+) and Tb(3+) → Mn(2+) energy transfer for WLEDs.

    PubMed

    Jiao, Mengmeng; Yang, Chuanlu; Li, Yalin; Wang, Dongxu; You, Hongpeng

    2017-09-20

    Color tunable Sr3LaNa(PO4)3F:Eu(2+),Tb(3+) and Sr3LaNa(PO4)3F:Tb(3+),Mn(2+) phosphors were prepared by a high temperature solid state reaction. The crystal structure, luminescence properties, and energy transfer mechanism of the samples were investigated in detail. The Eu(2+) doped phosphors can be efficiently excited in the range from 250 to 410 nm, which matches well with the commercial n-UV LED chips. Utilizing the energy transfer from Eu(2+) to Tb(3+) ions, tunable colors from blue to green were obtained under the irradiation of 405 nm. The mechanism of the Eu(2+) → Tb(3+) energy transfer was demonstrated to be a dipole-quadrupole interaction in terms of the experimental results and analysis of the photoluminescence spectra and decay curves of the phosphors. Moreover, the thermal stability and quantum efficiency of the Eu(2+) and Tb(3+) co-doped phosphors were studied. For the Sr3LaNa(PO4)3F:Tb(3+),Mn(2+) samples, tunable green-orange emissions were obtained by changing the relative ratio of Tb(3+) and Mn(2+) ions under 230 nm irradiation. The investigation results suggest that color tunable phosphors with potential for WLEDs were obtained utilizing the energy transfer process.

  20. 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

  1. Energy Transfer Efficiency from ZnO-Nanocrystals to Eu3+ Ions Embedded in SiO2 Film for Emission at 614 nm

    PubMed Central

    Pita, Kantisara

    2017-01-01

    In this work, we study the energy transfer mechanism from ZnO nanocrystals (ZnO-nc) to Eu3+ ions by fabricating thin-film samples of ZnO-nc and Eu3+ ions embedded in a SiO2 matrix using the low-cost sol-gel technique. The time-resolved photoluminescence (TRPL) measurements from the samples were analyzed to understand the contribution of energy transfer from the various ZnO-nc emission centers to Eu3+ ions. The decay time obtained from the TRPL measurements was used to calculate the energy transfer efficiencies from the ZnO-nc emission centers, and these results were compared with the energy transfer efficiencies calculated from steady-state photoluminescence emission results. The results in this work show that high transfer efficiencies from the excitonic and Zn defect emission centers is mostly due to the energy transfer from ZnO-nc to Eu3+ ions which results in the radiative emission from the Eu3+ ions at 614 nm, while the energy transfer from the oxygen defect emissions is most probably due to the energy transfer from ZnO-nc to the new defects created due to the incorporation of the Eu3+ ions. PMID:28796195

  2. Energy Transfer Efficiency from ZnO-Nanocrystals to Eu(3+) Ions Embedded in SiO₂ Film for Emission at 614 nm.

    PubMed

    Mangalam, Vivek; Pita, Kantisara

    2017-08-10

    In this work, we study the energy transfer mechanism from ZnO nanocrystals (ZnO-nc) to Eu(3+) ions by fabricating thin-film samples of ZnO-nc and Eu(3+) ions embedded in a SiO₂ matrix using the low-cost sol-gel technique. The time-resolved photoluminescence (TRPL) measurements from the samples were analyzed to understand the contribution of energy transfer from the various ZnO-nc emission centers to Eu(3+) ions. The decay time obtained from the TRPL measurements was used to calculate the energy transfer efficiencies from the ZnO-nc emission centers, and these results were compared with the energy transfer efficiencies calculated from steady-state photoluminescence emission results. The results in this work show that high transfer efficiencies from the excitonic and Zn defect emission centers is mostly due to the energy transfer from ZnO-nc to Eu(3+) ions which results in the radiative emission from the Eu(3+) ions at 614 nm, while the energy transfer from the oxygen defect emissions is most probably due to the energy transfer from ZnO-nc to the new defects created due to the incorporation of the Eu(3+) ions.

  3. A novel greenish yellow-orange red Ba3Y4O9:Bi(3+),Eu(3+) phosphor with efficient energy transfer for UV-LEDs.

    PubMed

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

    2015-12-21

    A series of novel color-tunable Ba3Y4O9:Bi(3+),Eu(3+) phosphors were prepared for the first time via the high-temperature solid-state reaction route. The effect of Bi(3+) concentration on the emission intensity of Ba3Y4O9:Bi(3+) was investigated. The emission spectra of the Ba3Y4O9:Bi(3+),Eu(3+) phosphors present both a greenish yellow band of Bi(3+) emission centered at 523 nm, and many characteristic emission lines of Eu(3+), derived from the allowed (3)P1-(1)S0 transition of the Bi(3+) ion and the (5)D0-(7)FJ transition of the Eu(3+) ion, respectively. The energy transfer phenomenon from Bi(3+) to Eu(3+) ions is observed under UV excitation in Bi(3+), Eu(3+) co-doped Ba3Y4O9 phosphors, and their transfer mechanism is demonstrated to be a resonant type via dipole-quadrupole interaction. The critical distance between Bi(3+) and Eu(3+) for the energy transfer effect was calculated via the concentration quenching and spectral overlap methods. Results show that color tuning from greenish yellow to orange red can be realized by adjusting the mole ratio of Bi(3+) and Eu(3+) concentrations based on the principle of energy transfer. Moreover, temperature-dependent PL properties, CIE chromaticity coordinates and quantum yields of Ba3Y4O9:Bi(3+),Eu(3+) phosphors were also supplied. It is illustrated that the as-prepared Ba3Y4O9:Bi(3+),Eu(3+) phosphors can be potential candidates for color-tunable phosphors applied in UV-pumped LEDs.

  4. Intramolecular energy transfer and co-luminescence effect in rare earth ions (La, Y, Gd and Tb) doped with Eu3+ beta-diketone complexes.

    PubMed

    Li, Ying; Zhao, Yongliang

    2009-07-01

    In this paper, Eu3+ beta-diketone Complexes with the two ligands 1-(2-naphthoyl)-3, 3, 3-trifluoroacetonate (TFNB) and 2'2-bipyridine (bpy) have been synthesized. Furthermore, we reported a systematical study of the co-fluorescence effect of Eu(TFNB)3bpy doped with inert rare earth ions (La3+, Gd3+ and Y3+) and luminescence ion Tb3+. The co-luminescence effect can be found by studying the luminescence spectra of the doped complexes, which means that the existence of the other rare earth ions (La3+, Y3+, Gd3+ and Tb3+) can enhance the luminescence intensity of the central Eu3+, which may be due to the intramolecular energy transfer between rare earth ions and Eu3+. The efficient intramolecular energy transfer in all the complexes mainly occurs between the ligand TFNB and the central Eu3+. Full characterization and detail studies of luminescence properties of all these synthesized materials were investigated in relation to co-fluorescence effect between the central Eu3+ and other inert ions. Further investigation into the luminescence properties of all the complexes show that the characteristic luminescence of the corresponding Eu3+ through the intramolecular energy transfers from the ligand to the central Eu3+. Meantime, the differences in luminescence intensity of the 5D0-->7F2 transition, in the 5D0 lifetimes and in the 5D0 luminescence quantum efficiency among all the synthesized materials confirm that the doped complex Eu(0.5)Tb(0.5)(TFNB)3bpy exhibits higher 5D0 luminescence quantum efficiency and longer lifetime than the pure Eu(TFNB)3bpy complex and other materials.

  5. 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

    2012-07-02

    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.

  6. 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…

  7. 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.

  8. 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

  9. Correlation of structural properties with energy transfer of Eu-doped ZnO thin films prepared by sol-gel process and magnetron reactive sputtering.

    PubMed

    Petersen, Julien; Brimont, Christelle; Gallart, Mathieu; Schmerber, Guy; Gilliot, Pierre; Ulhaq-Bouillet, Corinne; Rehspringer, Jean-Luc; Colis, Silviu; Becker, Claude; Slaoui, Abdelillah; Dinia, Aziz

    2010-06-15

    We investigated the structural and optical properties of Eu-doped ZnO thin films made by sol-gel technique and magnetron reactive sputtering on Si (100) substrate. The films elaborated by sol-gel process are polycrystalline while the films made by sputtering show a strongly textured growth along the c-axis. X-ray diffraction patterns and transmission electron microscopy analysis show that all samples are free of spurious phases. The presence of Eu(2+) and Eu(3+) into the ZnO matrix has been confirmed by x-ray photoemission spectroscopy. This means that a small fraction of Europium substitutes Zn(2+) as Eu(2+) into the ZnO matrix; the rest of Eu being in the trivalent state. This is probably due to the formation of Eu(2)O(3) oxide at the surface of ZnO particles. This is at the origin of the strong photoluminescence band observed at 2 eV, which is characteristic of the (5)D(0)-->(7)F(2) Eu(3+) transition. In addition the photoluminescence excitonic spectra showed efficient energy transfer from the ZnO matrix to the Eu(3+) ion, which is qualitatively similar for both films although the sputtered films have a better structural quality compared to the sol-gel process grown films.

  10. Correlation of structural properties with energy transfer of Eu-doped ZnO thin films prepared by sol-gel process and magnetron reactive sputtering

    PubMed Central

    Petersen, Julien; Brimont, Christelle; Gallart, Mathieu; Schmerber, Guy; Gilliot, Pierre; Ulhaq-Bouillet, Corinne; Rehspringer, Jean-Luc; Colis, Silviu; Becker, Claude; Slaoui, Abdelillah; Dinia, Aziz

    2010-01-01

    We investigated the structural and optical properties of Eu-doped ZnO thin films made by sol-gel technique and magnetron reactive sputtering on Si (100) substrate. The films elaborated by sol-gel process are polycrystalline while the films made by sputtering show a strongly textured growth along the c-axis. X-ray diffraction patterns and transmission electron microscopy analysis show that all samples are free of spurious phases. The presence of Eu2+ and Eu3+ into the ZnO matrix has been confirmed by x-ray photoemission spectroscopy. This means that a small fraction of Europium substitutes Zn2+ as Eu2+ into the ZnO matrix; the rest of Eu being in the trivalent state. This is probably due to the formation of Eu2O3 oxide at the surface of ZnO particles. This is at the origin of the strong photoluminescence band observed at 2 eV, which is characteristic of the 5D0→7F2 Eu3+ transition. In addition the photoluminescence excitonic spectra showed efficient energy transfer from the ZnO matrix to the Eu3+ ion, which is qualitatively similar for both films although the sputtered films have a better structural quality compared to the sol-gel process grown films. PMID:20644657

  11. 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.

  12. Luminescent properties and energy transfer studies of color-tunable LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors

    SciTech Connect

    Zhang, Xinguo; Fu, Xionghui; Song, Jiahui; Gong, Menglian

    2016-08-15

    Highlights: • A series of color-tunable LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors were synthesized. • Phosphors exhibit strong blue/green/red emission under UV excitation. • The reason of high Tb{sup 3+} content required for Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer is unveiled. • Green and red LED prototypes were fabricated and characterized. - Abstract: A series of LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors were synthesized via solid state reaction. The Ce{sup 3+}/Tb{sup 3+} co-doped and Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} tri-doped phosphors absorb near UV light through 4f-5d transitions of Ce{sup 3+}, followed by sensitized Tb{sup 3+} green and Eu{sup 3+} red emission. Decay curves investigations for samples with various Tb{sup 3+} and Eu{sup 3+} contents reveal the occurrence of Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer. It is found that due to relative low Tb{sup 3+} → Eu{sup 3+} energy transfer rate, a high Tb{sup 3+} content (>40%) is required for efficient Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer. Emission color of LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+}, Eu{sup 3+} varies from blue through green to red with Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} ratio. The quantum efficiency of LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+} green phosphor and LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+}, Eu{sup 3+} red phosphor is 50% and 30%, respectively. Green and red LED prototypes were fabricated. The results show that the obtained phosphors are potential candidates as down-converted phosphors for NUV LEDs.

  13. UV-Vis-NIR luminescence properties and energy transfer mechanism of LiSrPO4:Eu2+, Pr3+ suitable for solar spectral convertor.

    PubMed

    Chen, Yan; Wang, Jing; Liu, Chunmeng; Tang, Jinke; Kuang, Xiaojun; Wu, Mingmei; Su, Qiang

    2013-02-11

    An efficient near-infrared (NIR) phosphor LiSrPO(4):Eu(2+), Pr(3+) is synthesized by solid-state reaction and systematically investigated using x-ray diffraction, diffuse reflection spectrum, photoluminescence spectra at room temperature and 3 K, and the decay curves. The UV-Vis-NIR energy transfer mechanism is proposed based on these results. The results demonstrate Eu(2+) can be an efficient sensitizer for harvesting UV photon and greatly enhancing the NIR emission of Pr(3+) between 960 and 1060 nm through efficient energy feeding by allowed 4f-5d absorption of Eu(2+) with high oscillator strength. Eu(2+)/Pr(3+) may be an efficient donor-acceptor pair as solar spectral converter for Si solar cells.

  14. 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.

  15. 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.

  16. The greenGain project - Biomass from landscape conservation and maintenance work for renewable energy production in the EU

    NASA Astrophysics Data System (ADS)

    Clalüna, Aline; Baumgarten, Wibke; García Galindo, Daniel; Lenz, Klaus; Doležal, Jan; De Filippi, Federico; Lorenzo, Joaquín; Montagnoli, Louis

    2017-04-01

    The project greenGain is looking for solutions to increase the energy production with regional and local biomass from landscape conservation and maintenance work, which is performed in the public interest. The relevant resources analysed in the greenGain model regions are, among others, biomass residues from clearing invasive vegetation in marginal agricultural lands in Spain, and residues from abandoned vineyards and olive groves in landscape protected areas in Italy. The main target groups are regional and local players who are responsible for maintenance and conservation work and for the biomass residue management in their regions. Moreover, the focus will be on service providers - including farmers and forest owners, their associations, NGOs, energy providers and consumers. Local companies, municipalities and public authorities are collaborating to identify the still underutilised non-food biomass resources and to discuss the way to integrate them into the local and regional biomass markets. Since the start of the three year project in January 2015, the partners from Italy, Spain, Czech Republic and Germany analysed, among other, the biomass feedstock potential coming from landscape maintenance work, and assessed various technological options to utilise this type of biomass. Further, political, legal and environmental aspects as well as awareness raising and public acceptance actions regarding the energetic use of biomass from public areas were assessed. greenGain also facilitates the exchange between model regions and other similar relevant players in the EU and shares examples of good practice. General guidelines will be prepared to guarantee a wide dissemination to other regions in the EU. Thus, the project shows how to build-up reliable knowledge on local availability of this feedstock and provides know-how concerning planning, harvesting, pre-treatment, storage and sustainable conversion pathways to a wide range of stakeholders in the EU.

  17. 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.

  18. 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.

  19. 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.

  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.

  1. 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

  2. Synthesis and photoluminescence properties of multicolor tunable GdNbO4: Tb3+, Eu3+ phosphors based on energy transfer

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Yi, Shuangping; Hu, Xiaoxue; Liang, Boxin; Zhao, Weiren; Wang, Yinhai

    2017-03-01

    A color-tunable phosphor based on Tb3+/Eu3+ co-doped GdNbO4 were synthesized by a traditional solid-state reaction method. X-ray powder diffraction (XRD), diffuse reflectance spectra, photoluminescence spectra and decay curves were utilized to characterize the as-prepared phosphors. XRD result indicated that various concentrations Tb3+/Eu3+ single-doped and co-doped phosphors were well indexed to the pure GdNbO4 phase. The GdNbO4 host was proved to be a self-activated phosphor with broad absorption range from 200 nm to 325 nm. When Tb3+ ions were added into the host lattice, the energy transferring from host to Tb3+ was identified. And the broad absorption in the UV region was changed and enhanced. Therefore, we selected Tb3+ as the sensitizer ion, and adjusted red component from Eu3+ to control the emission color. The energy transfer from Tb3+ to Eu3+ was confirmed based on the luminescence spectra and decay curves. Furthermore, the energy transmission mechanism was deduced to be the dipole-quadrupole interaction. On the whole, the obtained GdNbO4, GdNbO4:Tb3+, and GdNbO4:Tb3+, Eu3+ phosphors may have potential application in the UV white-light-emitting diodes (w-LEDs) and display devices.

  3. 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.

  4. Energy transfer dynamics and luminescence properties of Eu(3+) in CaMoO4 and SrMoO4.

    PubMed

    Gupta, Santosh K; Sahu, M; Ghosh, P S; Tyagi, Deepak; Saxena, M K; Kadam, R M

    2015-11-21

    Undoped and europium doped CaMoO4 and SrMoO4 scheelites are synthesized using a complex polymerization method. The phase purity of the sample is confirmed using powder X-ray diffraction (PXRD). X-ray photoelectron spectroscopy (XPS) was carried out to confirm the oxidation states of various constituents and dopant elements and also the presence of oxygen vacancies. Interestingly both CaMoO4 and SrMoO4 on irradiation with UV light give blue and green emission respectively. On europium doping, it was found that molybdate to Eu(3+) ion energy transfer is more efficient in SrMoO4:Eu compared to CaMoO4:Eu. It is also justified using a luminescence lifetime study which shows biexponential decay in the case of CaMoO4:Eu corresponding to both the host and europium ion; whereas a single lifetime is observed in the case of SrMoO4:Eu. Anomalies in host-dopant energy transfer are suitably explained using density functional theory (DFT) calculations and XPS. The actual site symmetry for the europium ion in CaMoO4 and SrMoO4 was also evaluated based on a Stark splitting pattern which turns out to be D2 and C2v respectively although it is S4 for Ca/Ba(2+) in AMoO4. This is also reflected in higher Ω2 values for SrMoO4:Eu than CaMoO4:Eu.

  5. 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.

  6. Photoluminescence and energy transfer process in Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+}

    SciTech Connect

    Selvalakshmi, T.; Bose, A. Chandra

    2016-05-23

    Variation in photoluminescence (PL) properties of Eu{sup 3+} and Tb{sup 3+} as a function of co-dopant (Tb{sup 3+}) concentration are studied for Gd{sub 2-x-y}O{sub 3}: Eu{sup 3+}{sub x} Tb{sup 3+}{sub 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, Eu{sup 3+} and Tb{sup 3+}. 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 Eu{sup 3+} confirms the energy transfer from Tb{sup 3+} to Eu{sup 3+}. The agglomeration of particles acts as quenching centres for energy transfer at higher concentrations.

  7. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Energy Transfer from Ce3+ to Eu2+ in LiSrBO3 and Its Potential Application in UV-LED-Based White LEDs

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Jun; Li, Pan-Lai; Yang, Zhi-Ping; Guo, Qing-Lin; Fu, Guang-Sheng

    2009-11-01

    Ce3+/Eu2+ codoped LiSrBO3 phosphor is synthesized, and its luminescent characteristics are investigated. LiSrBO3:Ce3+,Eu2+ phosphor exhibits varied hues from blue to white and eventually to yellow by resonance-type energy transfer from Ce3+ ion to Eu2+ ion and tuning the relative proportion of Ce3+/Eu2+ properly. Energy transfer mechanism in LiSrBO3:Ce3+, Eu2+ phosphor is dominated by the dipole-dipole interaction, and the critical distance of the energy transfer is estimated to be about 2 nm by both spectral overlap and concentration quenching methods. Under UV radiation, white light is generated by coupling 436 and 565 nm emission bands attributed to Ce3+ and Eu2+ radiations, respectively.

  8. 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

  9. Enhanced Pr{sup 3+} photoluminescence by energy transfer in SrF{sub 2} : Eu{sup 2+}, Pr{sup 3+} phosphor

    SciTech Connect

    Yagoub, M. Y. A.; Swart, H. C.; Coetsee, E.; Bergman, P.

    2016-02-15

    Efficient energy transfer was demonstrated in the SrF{sub 2} : Eu{sup 2+}, Pr{sup 3+} phosphor synthesized by the co-precipitation method. Results obtained with X-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray spectroscopy (XPS), photoluminescence (PL) and decay curves proposed the UV-Vis energy transfer process. The energy transfer process between the Eu{sup 2+} and Pr{sup 3+} ions in SrF{sub 2} was investigated to evaluate the potential of the Eu{sup 2+} ion as a sensitizer for the Pr{sup 3+} ion. The results proposed that Eu{sup 2+} could be a good sensitizer for absorbing the UV photons and efficiently enhancing the Pr{sup 3+} emission intensity. The energy transfer process was effective until concentration quenching for the Pr{sup 3+} ions occurred. The concentration quenching was attributed to cross-relaxation between the Pr{sup 3+} ions.

  10. Photoluminescence, Dual-donor Energy Transfer and Single X-ray Crystallographic Studies of Eu3+ and Tb3+ complexes with pyridines and triazaphosphaadamantane oxide (TPAO) ligands

    NASA Astrophysics Data System (ADS)

    Forcha, Derick Akaju

    Coordination of several chromophoric ligands capable of sensitizing Tb 3+ and Eu3+ ions have been studied. Four new complexes of Eu3+ and Tb3+ ions were achieved by coordinating Eu with 4', 4''''- (1-4 phenylene) bis (2, 2':6', 2-terpyridine) , pyridino [2-3-b] pyrazines and 6,6‧‧-dibromo-2,2‧:6‧,2‧‧-terpyridine.The crystal structure of [Tb(TPAO)2(H2O) 4(Au(CN)2)3], was determined and shows a polymeric three-dimensional coordination with a monoclinic space group Cc, Z=4. The unit cell parameters are a = 17.4266(14) A, b = 10.8224(10) A, c = 18.0270(16) A, α = 90° beta = 109.309(3)° gamma = 90°. The structure exhibits an equilateral Au-Au-Au interaction bridged to a terbium core by the C-N groups. Three other complexes, viz [Eu(ppz) 2(H2O)n]Cl3, [Eu(ptpy)(H2O) n]Cl3 and [Eu(bbterp)(H2O)n]Cl 3, have also been synthesized and characterized using IR and luminescence spectroscopy, although no crystal was obtained suitable for X-ray diffraction analysis. The ligand tetra(2'-pyridyl)pyrazine (tppz) was also crystallized and its crystal structure solved. The results herein, elaborate the mode of dual donor sensitization from ligand groups to the lanthanide ions. The efficiency of energy transfer that occurs in the Ln3+ complexes has been calculated, taking into account the radiative and non radiative relaxation processes, and the limitation encountered. A broad excitation spectrum at 369, 366 and 380 nm were observed for [Eu(ppz)2(H2O) n]Cl3, [Eu(bbterp)(H2O)n]Cl3 and [Eu(ptpy)(H2O)n]Cl3 complexes, respectively upon monitoring the Eu3+ emission indicating the presence of ET in a donor-acceptor type interaction.

  11. A Tunable-Color Emission Phosphor Y₂O₃:Eu³⁺, Bi³⁺ with Efficient Energy Transfer for White Light Emitting Diodes.

    PubMed

    Jin, Ye; Zhou, Hong-Peng; Jiang, Ming-Song

    2016-01-01

    The Eu³⁺, Bi³⁺ ions co-doped Y₂O₃ phosphor has been synthesized by the conventional solid-state reaction method, and its photoluminescence (PL) spectra are investigated for application in white light emitting diode (LED). The Eu³⁺, Bi³⁺ ions co-doped Y₂O₃ phosphor showed a characteristic emissions with greenish blue and red color upon the near-UV light in the range of 310-360 nm, originating from ³P₁ --> ¹S₀ transition of Bi³⁺ and ⁵D₀ --> ⁷F(J) transition of Eu³⁺, respectively. As 613-nm emission of Eu³⁺ ions is monitored, excitation spectrum consists of two broad peaks near 230 nm and 330 nm, ascribed to the Eu³⁺-O²- charge transfer band (CTB) and the transition from the ground state to the excited states of Bi³⁺ ions, respectively. It implies that the energy transfer from Bi³⁺ ions to E³⁺ ions occur and the phosphor's color may be controlled by adjusting the concentrations of Eu³⁺ ions and Bi³⁺ons in Y20₂O₃The availability of this strategy is demonstrated in this work, and white light can be realized with superior chromaticity coordinates of (x = 0.337, y = 0.328) and a CCT of 5284 K for Y20₂O₃% Eu3+³⁺0.1% Bi3+³⁺Thus, it will be a promising candidate for the ultraviolet excitation white light emitting diode (LED).

  12. 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.

  13. Energy transfer and colour tunability in UV light induced Tm(3+)/Tb(3+)/Eu(3+): ZnB glasses generating white light emission.

    PubMed

    Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

    2017-03-15

    A promising energy transfer (Tm(3+)→Tb(3+)→Eu(3+)) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm(3+)/Tb(3+)/Eu(3+) ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II)x-[O(-II)]y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm(3+)/Tb(3+)/Eu(3+): ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: (1)D2→(3)F4), green (547nm: (5)D4→(7)F5) and red (616nm: (5)D0→(7)F2) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb(3+) in ET from Tm(3+)→Eu(3+) was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb(3+), Eu(3+)) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening.

  14. Energy transfer and colour tunability in UV light induced Tm3 +/Tb3 +/Eu3 +: ZnB glasses generating white light emission

    NASA Astrophysics Data System (ADS)

    Naresh, V.; Gupta, Kiran; Parthasaradhi Reddy, C.; Ham, Byoung S.

    2017-03-01

    A promising energy transfer (Tm3 + → Tb3 + → Eu3 +) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm3 +/Tb3 +/Eu3 + ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II)x-[O(- II)]y centres in the ZnB glass matrix. At 360 nm (UV) excitation, triply doped Tm3 +/Tb3 +/Eu3 +: ZnB glasses simultaneously shown their characteristic emission bands in blue (454 nm: 1D2 → 3F4), green (547 nm: 5D4 → 7F5) and red (616 nm: 5D0 → 7F2) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb3 + in ET from Tm3 + → Eu3 + was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb3 +, Eu3 +) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening.

  15. Calcination temperature optimization, energy transfer mechanism and fluorescence temperature dependence of KLa(MoO4)2:Eu3+ phosphors

    NASA Astrophysics Data System (ADS)

    Wu, Zhongli; Chen, Baojiu; Li, Xiangping; Sun, Jiashi; Zhang, Jinsu; Zhong, Hua; Zheng, Hui; Tong, Lili; Zhang, Xiangqing; Xia, Haiping

    2016-01-01

    The optimum calcination temperature for KLa(MoO4)2:Eu3+ phosphor was confirmed to be 1000 °C via checking the XRD patterns, SEM images and fluorescence spectra for the samples derived from solid state reaction. The energy transfer behavior between Eu3+ ions was studied. It was found that electric dipole-dipole interaction is responsible for the fluorescence quenching of 5D2 and 5D1 levels, but exchange interaction is in charge of 5D0 fluorescence quenching. It was also observed that color coordinates of the studied phosphor can be tuned when the doping concentration is relatively low. The fluorescence thermal quenching process was investigated. It was found the thermal quenching followed well crossover model. Judd-Ofelt parameters of Eu3+ in KLa(MoO4)2 were obtained, and the optical transition properties were further discussed.

  16. Energy transfer between Tb3+ and Eu3+ in co-doped Y2O3 nanocrystals prepared by Pechini method

    NASA Astrophysics Data System (ADS)

    Back, M.; Boffelli, M.; Massari, A.; Marin, R.; Enrichi, F.; Riello, P.

    2013-07-01

    Tb3+ and Eu3+ co-doped Y2O3 nanoparticles with a volume-weighted average size of about 30 nm were synthesized via simple Pechini-type sol-gel process. The growth of monocrystalline nanoparticles is investigated via XRD and TEM analysis. The study of energy transfer between Tb3+ and Eu3+ ions was carried out by means of PL, PLE, and photoluminescence decay analyses. The energy transfer from Tb3+ to Eu3+ is efficient and we show how a resonant type via a dipole-dipole interaction is the most probable mechanism. We compared the energy-transfer efficiencies calculated from the intensities and from the lifetimes of ^5{D}_4 longrightarrow ^7{F}_5 transition of Tb, showing the presence of two populations of Tb, with different local surroundings, in the matrix. Furthermore, the critical distance between Tb3+ and Eu3+ ions has been calculated by means of different theories, from a new probabilistic approach based on the discretization of the theory of Chandrasekhar about the distribution of the nearest neighbors in a random distribution of particles, and from the PL data, suggesting a value of about 7 Å.

  17. 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.

  18. Eu3 + amidst ionic copper in glass: Enhancement through energy transfer from Cu+, or quenching by Cu2 +?

    NASA Astrophysics Data System (ADS)

    Jiménez, José A.

    2017-02-01

    A barium-phosphate glass system doped with europium(III) and containing a high concentration of copper(I) together with a copper(II) remnant has been studied spectroscopically. The main object is to elucidate whether the orange-red emission of Eu3 + ions succeeds through sensitization via luminescent Cu+ ions or else is preferentially quenched by non-radiative transfer to Cu2 +. A characterization of the melt-quenched glass was first performed by UV/Vis optical absorption, 31P nuclear magnetic resonance and infrared absorption spectroscopy. A photoluminescence (PL) spectroscopy and emission decay dynamics assessment was subsequently performed. Despite the concentration of Cu+ being estimated to be much higher than that of Cu2 +, the data shows that quenching of Eu3 + PL by Cu2 + dominates. The lifetime analysis of emitting centers Cu+ and Eu3 + points to the origin of the manifestation being that the Eu3 + → Cu2 + non-radiative transfer rate responsible for the quenching is almost two times higher than that for the Cu+ → Eu3 + transfer accountable for the enhancement. Finally, an effort was made for the determination of Cu2 + in the glass containing Cu+, Cu2 + and Eu3 + ions based on the Eu3 + (5D0) emission decay rates. It was found to be in excellent agreement with the UV/Vis spectrophotometric approach, thus supporting the utility of Eu3 + ions for optical sensing of copper(II) in the solid state.

  19. The CERN-EU high-energy Reference Field (CERF) facility: applications and latest developments

    NASA Astrophysics Data System (ADS)

    Silari, Marco; Pozzi, Fabio

    2017-09-01

    The CERF facility at CERN provides an almost unique high-energy workplace reference radiation field for the calibration and test of radiation protection instrumentation employed at high-energy accelerator facilities and for aircraft and space dosimetry. This paper describes the main features of the facility and supplies a non-exhaustive list of recent (as of 2005) applications for which CERF is used. Upgrade work started in 2015 to provide the scientific and industrial communities with a state-of-the-art reference facility is also discussed.

  20. 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.

  1. A novel energy transfer inducing strong enhancement of electric dipole transition in Na3Mo12PO40:xEu3+ phosphors

    NASA Astrophysics Data System (ADS)

    Long, Jinqiao; Wang, Tianman; Luo, Zhirong; Gao, Yong; Song, Baoling; Liang, Jing; Liao, Sen; Huang, Yingheng; Zhang, Huaxin

    2017-08-01

    A series of Na3Mo12PO40:xEu3+ phosphors have been successfully synthesized by a solid-state method, and characterized by powder x-ray diffraction (PXRD). The PXRD results confirm that the samples have crystal phases of Na3Mo12PO40. For PL spectra of Na3Mo12PO40:2.0Eu3+ excited by 394 and 465 nm, R (R is the peak area ratio of 5D0  →  7F2 to 5D0  →  7F1) is only 1.46 with an excitation of 394 nm, but increases to 3.03 with an excitation of 465 nm. Furthermore, a new enhancement of electric dipole transition is observed. Emission spectrum (PL) intensity at 617 nm excited by 465 nm is 1.95 times as high as the excitation spectrum (PLE) intensity at 465 nm. Thus, cooperative energy transfers from the magnetic dipole (MD) Eu3+ center to the electric dipole (ED) Eu3+ center when excited by 465 nm is demonstrated for the new fluorescent behavior.

  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. Congressional Testimony: Testimony of Nikki Tinsley Before the Subcommittee on Energy Policy, Natural Resources and Regulatory Affairs Committee on Government Reform United States House

    EPA Pesticide Factsheets

    Testimony of the Honorable Nikki Tinsley Inspector General U.S. EPA Before the Subcommittee on Energy Policy, Natural Resources and Regulatory Affairs Committee on Government Reform United States House of Representatives

  5. d→f Energy Transfer in Ir(III)/Eu(III) Dyads: Use of a Naphthyl Spacer as a Spatial and Energetic “Stepping Stone”

    PubMed Central

    2013-01-01

    A series of luminescent complexes based on {Ir(phpy)2} (phpy = cyclometallating anion of 2-phenylpyridine) or {Ir(F2phpy)2} [F2phpy = cyclometallating anion of 2-(2′,4′-difluorophenyl)pyridine] units, with an additional 3-(2-pyridyl)-pyrazole (pypz) ligand, have been prepared; fluorination of the phenylpyridine ligands results in a blue-shift of the usual 3MLCT/3LC luminescence of the Ir unit from 477 to 455 nm. These complexes have pendant from the coordinated pyrazolyl ring an additional chelating 3-(2-pyridyl)-pyrazole unit, separated via a flexible chain containing a naphthalene-1,4-diyl or naphthalene-1,5-diyl spacer. Crystal structures show that the flexibility of the pendant chain allows the naphthyl group to lie close to the Ir core and participate in a π-stacking interaction with a coordinated phpy or F2phpy ligand. Luminescence spectra show that, whereas the {Ir(phpy)2(pypz)} complexes show typical Ir-based emission—albeit with lengthened lifetimes because of interaction with the stacked naphthyl group—the {Ir(F2phpy)2(pypz)} complexes are nearly quenched. This is because the higher energy of the Ir-based 3MLCT/3LC excited state can now be quenched by the adjacent naphthyl group to form a long-lived naphthyl-centered triplet (3nap) state which is detectable by transient absorption. Coordination of an {Eu(hfac)3} unit (hfac = 1,1,1,5,5,5-hexafluoro-pentane-2,4-dionate) to the pendant pypz binding site affords Ir–naphthyl–Eu triads. For the triads containing a {Ir(phpy)2} core, the unavailability of the 3nap state (not populated by the Ir-based excited state which is too low in energy) means that direct Ir→Eu energy-transfer occurs in the same way as in other flexible Ir/Eu complexes. However for the triads based on the{Ir(F2phpy)2} core, the initial Ir→3nap energy-transfer step is followed by a second, slower, 3nap→Eu energy-transfer step: transient absorption measurements clearly show the 3nap state being sensitized by the Ir center

  6. 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

    2015-04-06

    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.

  7. The size confinement effect for Ln3+ (Ln = Tm or Eu) concentration quenching and energy transfer in Y2O3 nanocrystals.

    PubMed

    Wang, Changwen; Meng, Qingyu

    2014-05-01

    Y2O3:Ln (Ln = Tm or Eu) nano-powders with different particle sizes and various doping concentrations were prepared by using a combustion method. The bulk powders doped with the same concentrations were obtained by annealing the nano-powders at high temperatures. Emission spectra of the phosphors were measured. The crystal structure and morphology of the phosphors were characterized by XRD (X-ray diffraction) and FE-SEM (field emission scanning electron microscopy), respectively. The concentration quenching of luminescent centers and energy transfer between luminescent centers in Y2O3:Ln nanocrystal powders were investigated. It is found that the behavior of luminescent concentration quenching for Eu3+ 5D0 --> 7F2 in nano-powders is similar to that in bulk powders. On the contrary, the quenching concentration for Tm3+ 1D2 --> 3H4 is distinctly higher than that in bulk powders. This owes to the size confinement effect which will restrain the electric dipole-dipole interaction as a long-rang interaction (e.g., energy transfer between Tm3+ ions), and will hardly affect the exchange interaction which is a short-rang interaction (e.g., energy transfer between Eu3+ ions).

  8. 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.

  9. Layered rare-earth hydroxide and oxide nanoplates of the Y/Tb/Eu system: phase-controlled processing, structure characterization and color-tunable photoluminescence via selective excitation and efficient energy transfer.

    PubMed

    Wu, Xiaoli; Li, Ji-Guang; Li, Jinkai; Zhu, Qi; Li, Xiaodong; Sun, Xudong; Sakka, Yoshio

    2013-02-01

    Well-crystallized (Y0.97-x Tb0.03Eu x )2(OH)5NO3·nH2O (x = 0-0.03) layered rare-earth hydroxide (LRH) nanoflakes of a pure high-hydration phase have been produced by autoclaving from the nitrate/NH4OH reaction system under the optimized conditions of 100 °C and pH ∼7.0. The flakes were then converted into (Y0.97-x Tb0.03Eu x )2O3 phosphor nanoplates with color-tunable photoluminescence. Detailed structural characterizations confirmed that LRH solid solutions contained NO3(-) anions intercalated between the layers. Characteristic Tb(3+) and Eu(3+) emissions were detected in the ternary LRHs by selectively exciting the two types of activators, and the energy transfer from Tb(3+) to Eu(3+) was observed. Annealing the LRHs at 1100 °C produced cubic-lattice (Y0.97-x Tb0.03Eu x )2O3 solid-solution nanoplates with exposed 222 facets. Multicolor, intensity-adjustable luminescence was attained by varying the excitation wavelength from ∼249 nm (the charge transfer excitation band of Eu(3+)) to 278 nm (the 4f(8)-4f(7)5d(1) transition of Tb(3+)). Unitizing the efficient Tb(3+) to Eu(3+) energy transfer, the emission color of (Y0.97-x Tb0.03Eu x )2O3 was tuned from approximately green to yellowish-orange by varying the Eu(3+)/Tb(3+) ratio. At the optimal Eu(3+) content of x = 0.01, the efficiency of energy transfer was ∼91% and the transfer mechanism was suggested to be electric multipole interactions. The phosphor nanoplates developed in this work may be incorporated in luminescent films and find various lighting and display applications.

  10. Broadband Luminescence in Rare Earth Doped Sr2SiS4: Relating Energy Levels of Ce3+ and Eu2+

    PubMed Central

    Parmentier, Anthony B.; Smet, Philippe F.; Poelman, Dirk

    2013-01-01

    Sr2SiS4:Ce3+ is an efficient blue-emitting (460 nm) phosphor, excitable with light of wavelengths up to 420 nm. From the excitation spectrum, we construct the energy level scheme and use it to check the predictive power of the Dorenbos model, relating the positions of the Ce3+ energy levels with those of Eu2+ in the same host. For strontium thiosilicate, this method gives excellent results and allows us to determine which of two available crystallographic sites is occupied by cerium. We use the Dorenbos method for extracting information on the coordination of Ce3+ from the observed crystal field splitting. PMID:28811459

  11. 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.

  12. Luminescence characteristic of RE (RE = Pr, Sm, Eu, Tb, Dy) and energy levels of lanthanide ions in Gd5Si3O12N

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Jun; Yang, Woochul

    2017-10-01

    Polycrystalline Gd5Si3O12N: RE (RE = Pr, Sm, Eu, Tb and Dy) phosphors have been synthesized via a solid-state reaction method at high temperature, and their photoluminescence properties were studied. The absorption peak at about 230 nm is attributed to the host absorption. For the Pr3+-doped sample, the typical excitation lines located at 273 nm originating from the 8S7/2 → 6IJ (J = 5/2, 7/2) transitions of the Gd3+ ions were observed in the excitation spectra. Upon excitation at 227 nm UV light, the 4f15d → 4f2 emission band (350-450 nm) and typical 4f2 → 4f2 emission lines (450-700 nm) assigned to Pr3+ were observed. The Sm3+-doped sample exhibits a bright red emission owing to the 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2) transitions. However, the charge transfer band of Sm3+ was not observed in the excitation spectrum. There is a broad band from 200 to 350 nm originating from the charge transfer transition (CT) of the Eu3+ (O2-/N3- → Eu3+) in the excitation spectra, and the strongest peak in the emission spectra located at 615 nm is due to the electric-dipole 5D0 → 7F2 transition of Eu3+. For the Tb3+-doped sample, it shows 5D3 →7FJ (J = 5, 4, 3, 2) blue line emissions and 5D4 → 7FJ (J = 6, 5, 4, 3) green line emissions under the excitation of Tb3+. The Dy3+-activated sample upon excitation at 349 and 386 nm UV light shows blue-green and orange-red emission lines originating from 4F9/2 → 6HJ (J = 15/2, 13/2) transitions. In addition, the energy transfer from the host lattice to the luminescence activators (i.e. Pr3+, Sm3+, Eu3+, Tb3+, Dy3+) has been confirmed. In addition, the energy level diagram including the 4f and 5d energy levels of all Ln2+ and Ln3+ ions relative to the valence and conduction band of Gd5Si3O12N were constructed and discussed.

  13. Energy transfer and luminescence properties of Sr[1-3(x+y)/2]Al₂B₂O₇:xEu³⁺, yBi³⁺ phosphor.

    PubMed

    Cao, Renping; Liang, Tao; Li, Wensheng; Cao, Chunyan; Wen, Yufeng; Hu, Qianglin

    2015-07-05

    Sr[1-3(x+y)/2]Al2B2O7:xEu(3+), yBi(3+) (x=0-5 mol% and y=0-5 mol%) phosphors are synthesized by a solid-state reaction method in air, and their crystal structure, fluorescence lifetime, and luminescence properties are investigated. The optimal composition is determined to be (Sr0.94Eu0.03Bi0.01)Al2B2O7. The PLE band peaks within the range 200-550 nm are due to O(2-)→Eu(3+) charge transfer band, (7)F0→(5)H3, (5)D4, (5)L7, (5)L6, (5)D3, (5)D2, and (5)D1 transitions, respectively. The strongest PL band peak under excitation 394 nm light is at ∼615 nm owing to (5)D0→(7)F2 transition of Eu(3+) ion. The PL intensity of Eu(3+), Bi(3+) co-doped SrAl2B2O7 phosphor is 1.3 times that of Eu(3+) doped SrAl2B2O7 phosphor due to the energy transfer between Eu(3+) and Bi(3+) ions, which is explained by the energy level diagrams of Bi(3+) and Eu(3+) ions. The CIE chromaticity coordinates of Sr0.955Al2B2O7:0.03Eu(3+) and Sr0.94Al2B2O7:0.03Eu(3+), 0.01Bi(3+) phosphors under excitation 394 nm light are (x=0.6292, y=0.3702) and (x=0.6284, y=0.3711), respectively. These phosphors will be used as reddish orange emitting phosphor candidate for white LED with ∼394 nm near ultraviolet LED chip.

  14. Energy transfer and tunable luminescence of Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} phosphors for white LED applications

    SciTech Connect

    Zheng, Zhang; Wanjun, Tang

    2016-01-15

    Highlights: • Iso-structural garnet-type Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} solid solution were synthesized. • Efficient energy transfer from [VO{sub 4}]{sup 3−} to Eu{sup 3+} ions in this phosphor is observed obviously. • Tuning the Y/Eu ratio generates the varied hues from yellowish-green to reddish-orange. • This kind of phosphor can be potentially used in UV pumped LEDs. - Abstract: A series of solid-solution phosphors Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} were prepared using solution combustion reaction. X-ray diffraction studies verified the formation of single phase Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} with garnet structure. Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} phosphors show not only a broad emission band with a maximum at 510 nm due to the [VO{sub 4}]{sup 3−} group but also several sharp emission lines due to the Eu{sup 3+} ions. The energy transfer from [VO{sub 4}]{sup 3−} to Eu{sup 3+} was discussed on the base of the spectral analysis. The color-tunable emissions of the Na{sub 2}(Y,Eu)Mg{sub 2}V{sub 3}O{sub 12} phosphor as a function of Y/Eu ratio are realized by continuously generating the varied hues from yellowish-green to reddish-orange. This indicates that the obtained phosphor may have potential applications in the field of UV-based white LEDs.

  15. Color-tunable photoluminescence and energy transfer properties of single-phase Ba{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+}, Mn{sup 2+} phosphors

    SciTech Connect

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

    2015-12-15

    Single-phase Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} 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 Eu{sup 2+} to Mn{sup 2+} in Ba{sub 10}(PO{sub 4}){sub 6}O and a possible mechanism of the energy-transfer from Eu{sup 2+} to Mn{sup 2+} is proposed. The critical distances R{sub c} was calculated by concentration quenching and turned out to be about 0.817 nm (x{sub c}=0.21). The CIE and thermally stable luminescence behaviors of Ba{sub 9.94}(PO{sub 4}){sub 6}O:0.06Eu{sup 2+} phosphor were also studied in detail. All the results indicate that Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+}, yMn{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white light-emitting diodes. - Graphical abstract: Crystal structure and luminescence property of Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} have been discussed. - Highlights: • Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} was firstly reported. • Ba{sub 9.94}(PO{sub 4}){sub 6}O:0.06Eu{sup 2+} exhibits high thermal quenching resistance. • The energy transfer between Eu{sup 2+} and Mn{sup 2+} was investigated.

  16. Single-component and warm-white-emitting phosphor NaGd(WO4)2:Tm3+, Dy3+, Eu3+: synthesis, luminescence, energy transfer, and tunable color.

    PubMed

    Liu, Yan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2014-11-03

    Tm(3+), Dy(3+), and Eu(3+) codoped NaGd(WO4)2 phosphors were prepared by a facile hydrothermal process; they were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectrometer (EDS), photoluminescence spectra, and fluorescence lifetime. The results show that the novel octahedral microcrystals with a mean side length of 2 μm are obtained. Under the excitation of ultraviolet, individual RE(3+) ion (Tm(3+), Dy(3+), and Eu(3+)) activated NaGd(WO4)2 phosphors exhibit excellent emission properties in their respective regions. Moreover, when codoping Dy(3+) and Eu(3+)/Tm(3+) in the single component, the energy migration from Dy(3+) to Eu(3+) has been demonstrated to be a resonant type via a dipole-quadrupole mechanism as well as that from Tm(3+) to Dy(3+) ions, of which the critical distance (R(Dy-Eu)) is calculated to be 11.08 Å. More significantly, in the Tm(3+), Dy(3+), and Eu(3+) tridoped NaGd(WO4)2 phosphors, the energy migration of Tm(3+)-Dy(3+)-Eu(3+), utilized for sensitizing Eu(3+) ions besides compensating the red component at low Eu(3+) doping concentration, has been discussed first. In addition, under 365 nm near-ultraviolet radiation (nUV), the color-tunable emissions in octahedral NaGd(WO4)2 microcrystals are realized by giving abundant blue, green, white, yellow, and red emissions, especially warm white emission, and could be favorable candidates in full-color phosphors for nUV-LEDs.

  17. Controlled Energy Transfer from a Ligand to an Eu(III) Ion: A Unique Strategy To Obtain Bright-White-Light Emission and Its Versatile Applications.

    PubMed

    Boddula, Rajamouli; Singh, Kasturi; Giri, Santanab; Vaidyanathan, Sivakumar

    2017-09-05

    A new diphenylamine-functionalized ancillary-ligand-coordinated europium(III) β-diketonate complex showed incomplete photoexcitation energy transfer from a ligand to a Eu(III) ion. A solvatochromism study led to a balancing of the primary colors to obtain single-molecule white-light emission. Thermal-sensing analysis of the europium complex was executed. The europium complex, conjugated with a near-UV-light-emitting diode (395 nm), showed appropriate white-light-emission CIE color coordinates (x = 0.34 and y = 0.33) with a 5152 K correlated color temperature.

  18. Self-assembly synthesis, structural features, and photophysical properties of dilanthanide complexes derived from a novel amide type ligand: energy transfer from Tb(III) to Eu(III) in a heterodinuclear derivative.

    PubMed

    Gao, Cunji; Kirillov, Alexander M; Dou, Wei; Tang, Xiaoliang; Liu, Liangliang; Yan, Xuhuan; Xie, Yujie; Zang, Peixian; Liu, Weisheng; Tang, Yu

    2014-01-21

    A novel amide type ligand benzyl-N,N-bis[(2'-furfurylaminoformyl)phenoxyl)ethyl]-amine (L) has been designed and applied for the self-assembly generation of homodinuclear lanthanide coordination compounds [Ln2(μ2-L)2(NO3)6(EtOH)2] [Ln = Eu (1), Tb (2), and Gd (3)] and a heterodinuclear derivative [EuTb(μ2-L)2(NO3)6(EtOH)2] (4). All the complexes have been characterized by the X-ray single-crystal diffraction analyses. They are isostructural, crystallize in a monoclinic space group P21/c, and form [2 + 2] rectangular macrocycle structures. Compound 4 is the first example of a [2 + 2] rectangular macrocycle heterodinuclear EuTb complex assembled from an amide type ligand. In 4, the discrete 0D dimeric [EuTb(μ2-L)2(NO3)6(EtOH)2] units are extended, via the multiple N-H···O hydrogen bonds, into a 2D supramolecular network that has been topologically classified as a uninodal 4-connected underlying net with the sql [Shubnikov tetragonal plane net] topology. The triplet state ((3)ππ*) of L studied by the Gd(III) complex 3 demonstrated that the ligand beautifully populates Tb(III) emission (Φ = 52%), whereas the corresponding Eu(III) derivative 1 shows weak luminescence efficiency (Φ = 0.7%) because the triplet state of L has a poor match with (5)D1 energy level of Eu(III). Furthermore, the photoluminescent properties of heterodinuclear complex 4 have been compared with those of the analogous homodinuclear compounds. The quantum yield and lifetime measurements prove that energy transfer from Tb(III) to Eu(III) is being achieved, namely, that the Tb(III) center is also acting to sensitize the Eu(III) and enhancing Eu(III) emission in 4.

  19. Dispersal and reformation of acetylcholine receptor clusters of cultured rat myotubes treated with inhibitors of energy metabolism.

    PubMed

    Bloch, R J

    1979-09-01

    The effects of energy metabolism inhibitors on the distribution of acetylcholine receptors (AChRs) in the surface membranes of non-innervated, cultured rat myotubes were studied by visualizing the AChRs with monotetramethylrhodamine-alpha-bungarotoxin. Incubation of myotubes with inhibitors of energy metabolism causes a large decrease in the fraction of myotubes displaying clusters of AChR. This decrease is reversible, and is dependent on temperature, the concentration of inhibitor, and the duration of treatment. Cluster dispersal is probably not the result of secondary effects on Ca++ or cyclic nucleotide metabolism, membrane potential, cytoskeletal elements, or protein synthesis. Sequential observations of identified cells treated with sodium azide showed that clusters appear to disperse by movements of receptors within the sarcolemma without accompanying changes in cell shape. AChR clusters dispersed by pretreating cells with sodium azide rapidly reform upon removal of the inhibitor. Reclustering involves the formation of small aggregates of AChR, which act as foci for further aggregation and which appear to be precursors of large AChR clusters. Small AChR aggregates also appear to be precursors of clusters which form on myotubes never exposed to azide. Reclustering after azide treatment does not necessarily occur at the same sites occupied by clusters before dispersal, nor does it employ only receptors which had previously been in clusters. Cluster reformation can be blocked by cycloheximide, colchicine, and drugs which alter the intracellular cation composition.

  20. Efficient energy transfer and luminescence properties of Ca3Y(GaO)3(BO3)4:Tb(3+),Eu(3+) as a green-to-red colour tunable phosphor under near-UV excitation.

    PubMed

    Khan, Wasim Ullah; Li, Junhao; Li, Xiaohui; Wu, Qili; Yan, Jing; Xu, Yiqin; Xie, Feiyan; Shi, Jianxin; Wu, Mingmei

    2017-02-14

    A series of Ca3Y(GaO)3(BO3)4:Tb(3+),Eu(3+) phosphors were prepared by a high-temperature solid-state reaction. Their phase structures were confirmed by powder X-ray diffraction and the element distribution was measured using transmission electron microscopy elemental mapping. The photoluminescence emission and excitation spectra and fluorescence lifetime were studied and discussed in detail. The results revealed that Eu(3+) ions can be efficiently sensitized by Tb(3+) ions under near-UV excitation. In addition, the energy transfer efficiency can be controlled by adjusting the ratio of Eu(3+) and Tb(3+) to realize colour tunable emission from green to red. For Ca3Y(GaO)3(BO3)4:0.50Tb(3+),0.10Eu(3+), the emission intensity at 425 K is 78.11% of that at 300 K, being available to near-UV LEDs.

  1. Reforming Science: Structural Reforms

    PubMed Central

    2012-01-01

    Science has a critical role to play in addressing humanity's most important challenges in the twenty-first century. However, the contemporary scientific enterprise has developed in ways that prevent it from reaching maximum effectiveness and detract from the appeal of a research career. To be effective, the methodological and culture reforms discussed in the accompanying essay must be accompanied by fundamental structural reforms that include a renewed vigorous societal investment in science and scientists. PMID:22184420

  2. Enhanced green and orange photoluminescence of nanostructured CdS in glass nanocomposites by energy transfer From Ho3+ and Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Dey, Chirantan; Karmakar, Basudeb

    2017-01-01

    We report enhanced photoluminescence (PL) of both band edge and trap state emissions in Ho3+ or Eu3+ ion doped CdS (II-VI semiconductor) nanoparticles (NPs) containing glass nanocomposites. These glass nanocomposites were synthesized by the conventional melt-quench technique. The sizes of CdS NPs are found to increase from 5-15 nm to 40-80 nm with the increase in thermal treatment. Band edge emission (green emission, peak around 495 nm) of CdS NPs is controlled by their size and enhanced about three to nine-fold by Ho3+ ions on excitation at 446 nm by a diode laser. Under the same excitation, twelve to fifty-fold enhanced trap state emission (orange and red emissions about 550-900 nm) of CdS NPs is obtained by Eu3+-doping compared to undoped CdS NPs containing glass nanocomposites. The predominant mechanism of PL enhancement is the energy transfer from rare earth ions to CdS NPs. Enhanced PL of these nanocomposites enables their applications in efficient solar concentrators, green and red light emitting component for white light emission devices.

  3. Catalytic Reforming

    SciTech Connect

    Little, D.M.

    1985-01-01

    Don Little's Catalytic Reforming deals exclusively with reforming. With the increasing need for unleaded gasoline, the importance of this volume has escalated since it combines various related aspects of reforming technology into a single publication. For those with no practical knowledge of catalytic reforming, the chemical reactions, flow schemes and how the cat reformer fits into the overall refinery process will be of interest. Contents include: Catalytic reforming in refinery processing: How catalytic reformers work - chemical reactions; Process design; The catalyst, process variables and unit operation; Commercial processes; BTX operation; Feed preparation; naphtha hydrotreating and catalytic reforming; Index.

  4. Luminescence and energy-transfer properties of color-tunable Ca2Mg0.25Al1.5Si1.25O7: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 Ca2Mg0.25Al1.5Si1.25O7: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 Ca2Mg0.25Al1.5Si1.25O7:Ce(3+),Eu(2+) and Ca2Mg0.25Al1.5Si1.25O7: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 Ca2Mg0.25Al1.5Si1.25O7: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.

  5. Instrument intercomparison in the high-energy mixed field at the CERN-EU reference field (CERF) facility.

    PubMed

    Caresana, Marco; Helmecke, Manuela; Kubancak, Jan; Manessi, Giacomo Paolo; Ott, Klaus; Scherpelz, Robert; Silari, Marco

    2014-10-01

    This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1σ with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10).

  6. A single-composition CaSi2O2N2:RE (RE=Ce3+/Tb3+, Eu2+, Mn2+) phosphor nanofiber mat: Energy transfer, luminescence and tunable color properties

    NASA Astrophysics Data System (ADS)

    Cui, Bo; Chen, Zhenhua; Zhang, Qinghong; Wang, Hongzhi; Li, Yaogang

    2017-09-01

    CaSi2O2N2:RE (RE = Ce3+/Tb3+, Eu2+, Mn2+) phosphor nanofiber mat has been prepared via the electrospinning process and further annealing treatment. The diameter of nanofiber precursors are generally in a range of 400-600 nm, which exhibits smooth and uniform surface morphology. After removing the polymer template by high temperature treatment, the fabricated mats have been transformed into a phosphor film and maintain uniform nanofiber network microstructures. Photoluminescence (PL) properties of CaSi2O2N2 phosphor nanofiber mat have been activated by Ce3+/Tb3+, Eu2+ and Mn2+. The emission color of CaSi2O2N2:Ce3+/Tb3+, Eu2+, Mn2+ phosphor mats can be adjusted by modifying the concentration of doped Tb3+/Mn2+/Eu2+ and the resultant energy transfer process. Owing to the energy transfer of Ce3+-Tb3+, the emitting color of the phosphor mat can be changed from blue to green. Meanwhile, we still found that the switching of emitting colors from blue to red and blue to yellow can be achieved via the energy transfer of Ce3+-Mn2+ and Ce3+-Eu2+, respectively. We demonstrated a white light emission phosphor nanofiber mat by using CaSi2O2N2 system, which exhibited promising applications for near-UV WLEDs.

  7. Sensitisation of Eu(III)- and Tb(III)-based luminescence by Ir(III) units in Ir/lanthanide dyads: evidence for parallel energy-transfer and electron-transfer based mechanisms.

    PubMed

    Sykes, Daniel; Cankut, Ahmet J; Ali, Noorshida Mohd; Stephenson, Andrew; Spall, Steven J P; Parker, Simon C; Weinstein, Julia A; Ward, Michael D

    2014-05-07

    A series of blue-luminescent Ir(III) complexes with a pendant binding site for lanthanide(III) ions has been synthesized and used to prepare Ir(III)/Ln(III) dyads (Ln = Eu, Tb, Gd). Photophysical studies were used to establish mechanisms of Ir→Ln (Ln = Tb, Eu) energy-transfer. In the Ir/Gd dyads, where direct Ir→Gd energy-transfer is not possible, significant quenching of Ir-based luminescence nonetheless occurred; this can be ascribed to photoinduced electron-transfer from the photo-excited Ir unit (*Ir, (3)MLCT/(3)LC excited state) to the pendant pyrazolyl-pyridine site which becomes a good electron-acceptor when coordinated to an electropositive Gd(III) centre. This electron transfer quenches the Ir-based luminescence, leading to formation of a charge-separated {Ir(4+)}˙-(pyrazolyl-pyridine)˙(-) state, which is short-lived possibly due to fast back electron-transfer (<20 ns). In the Ir/Tb and Ir/Eu dyads this electron-transfer pathway is again operative and leads to sensitisation of Eu-based and Tb-based emission using the energy liberated from the back electron-transfer process. In addition direct Dexter-type Ir→Ln (Ln = Tb, Eu) energy-transfer occurs on a similar timescale, meaning that there are two parallel mechanisms by which excitation energy can be transferred from *Ir to the Eu/Tb centre. Time-resolved luminescence measurements on the sensitised Eu-based emission showed both fast and slow rise-time components, associated with the PET-based and Dexter-based energy-transfer mechanisms respectively. In the Ir/Tb dyads, the Ir→Tb energy-transfer is only just thermodynamically favourable, leading to rapid Tb→Ir thermally-activated back energy-transfer and non-radiative deactivation to an extent that depends on the precise energy gap between the *Ir and Tb-based (5)D4 states. Thus, the sensitised Tb(iii)-based emission is weak and unusually short-lived due to back energy transfer, but nonetheless represents rare examples of Tb(III) sensitisation by

  8. 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.

  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.

  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. The energy transfer phenomena and colour tunability in Y2O2S:Eu(3+)/Dy(3+) micro-fibers for white emission in solid state lighting applications.

    PubMed

    Som, S; Mitra, P; Kumar, Vijay; Kumar, Vinod; Terblans, J J; Swart, H C; Sharma, S K

    2014-07-14

    This paper reports on the structural, optical and photometric characterization of an Eu(3+)/Dy(3+) doped yttrium oxysulfide phosphor (Y2O2S:Eu(3+)/Dy(3+)) for near white emission in solid state lighting. A series of Y2O2S phosphors doped with Eu(3+)/Dy(3+) were prepared by the hydrothermal method. The microstructures of the as-synthesized phosphors were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results reveal that the obtained powder phosphors have a single-phase hexagonal structure and also indicate that the incorporation of the dopants/co-dopants did not affect the crystal structure. The SEM images reveal the morphology of the prepared phosphors as an intense interpenetrating network of interconnected micro-fibers with a diameter of about 0.15 μm. The band gap of the phosphors was calculated from diffuse reflectance spectra using the Kubelka-Munk function. The Eu(3+), Dy(3+) doped and Eu(3+)/Dy(3+) co-doped phosphors illuminated with ultraviolet light showed characteristic red luminescence corresponding to the (5)D0→(7)FJ transitions of Eu(3+) and characteristic blue and yellow luminescence corresponding to the (4)F9/2→(6)H15/2 or (4)F9/2→(6)H13/2 transitions of Dy(3+). The luminescence spectra, the energy transfer efficiency and the decay curves of the phosphors indicated that there exists a strong energy transfer from Dy(3+) to Eu(3+) and this was demonstrated to be a resonant type via a dipole-quadrupole reaction. Furthermore, the critical distance of the Eu(3+) and Dy(3+) ions have also been calculated. By utilizing the principle of energy transfer it was also demonstrated that with an appropriate tuning of the activator content the Y2O2S:Eu(3+)/Dy(3+) phosphors can exhibit a great potential to act as single-emitting component phosphors for white light emission in solid state lighting technology.

  12. 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.

  13. NETL - Fuel Reforming Facilities

    ScienceCinema

    None

    2016-07-12

    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.

  14. 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

    2013-10-07

    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.

  15. Layered rare-earth hydroxide and oxide nanoplates of the Y/Tb/Eu system: phase-controlled processing, structure characterization and color-tunable photoluminescence via selective excitation and efficient energy transfer

    PubMed Central

    Wu, Xiaoli; Li, Ji-Guang; Li, Jinkai; Zhu, Qi; Li, Xiaodong; Sun, Xudong; Sakka, Yoshio

    2013-01-01

    Well-crystallized (Y0.97−xTb0.03Eux)2(OH)5NO3·nH2O (x = 0–0.03) layered rare-earth hydroxide (LRH) nanoflakes of a pure high-hydration phase have been produced by autoclaving from the nitrate/NH4OH reaction system under the optimized conditions of 100 °C and pH ∼7.0. The flakes were then converted into (Y0.97−xTb0.03Eux)2O3 phosphor nanoplates with color-tunable photoluminescence. Detailed structural characterizations confirmed that LRH solid solutions contained NO3− anions intercalated between the layers. Characteristic Tb3+ and Eu3+ emissions were detected in the ternary LRHs by selectively exciting the two types of activators, and the energy transfer from Tb3+ to Eu3+ was observed. Annealing the LRHs at 1100 °C produced cubic-lattice (Y0.97−xTb0.03Eux)2O3 solid-solution nanoplates with exposed 222 facets. Multicolor, intensity-adjustable luminescence was attained by varying the excitation wavelength from ∼249 nm (the charge transfer excitation band of Eu3+) to 278 nm (the 4f8–4f75d1 transition of Tb3+). Unitizing the efficient Tb3+ to Eu3+ energy transfer, the emission color of (Y0.97−xTb0.03Eux)2O3 was tuned from approximately green to yellowish-orange by varying the Eu3+/Tb3+ ratio. At the optimal Eu3+ content of x = 0.01, the efficiency of energy transfer was ∼91% and the transfer mechanism was suggested to be electric multipole interactions. The phosphor nanoplates developed in this work may be incorporated in luminescent films and find various lighting and display applications. PMID:27877564

  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.

  17. Measurement of Linear Energy Transfer Distribution at CERN-EU High-Energy Reference Field Facility with Real-Time Radiation Monitoring Device III and Its Comparison with Dosimetric Telescope

    NASA Astrophysics Data System (ADS)

    Doke, Tadayoshi; Fuse, Tetsuhito; Hara, Kenichiro; Hayashi, Takayoshi; Kikuchi, Jun; Suzuki, Satoshi; Terasawa, Kazuhiro

    2004-06-01

    The distributions of linear energy transfer for LET (LETwater) in front of the 80-cm-thick concrete side shield at the CERN-EU high-energy reference field (CERF) facility were measured with a Si detector telescope named real-time radiation monitoring device-III (RRMD-III) covered with and without a 1 cm-thick acrylic plate. In these measurements, a difference of about 20% in the absorbed dose between the two LETwater distributions was observed as a result of protons, deuterons and tritons recoiled by neutrons. The LETwater distribution obtained using RRMD-III without the 1-cm-thick acrylic plate is compared with lineal energy distributions obtained using the dosimetric telescope (DOSTEL) detector under the same conditions. These dose equivalents are also compared with that obtained using HANDI TEPC which is used as the standard at the CERF facility.

  18. Modeling of policies for reduction of GHG emissions in energy sector using ANN: case study-Croatia (EU).

    PubMed

    Bolanča, Tomislav; Strahovnik, Tomislav; Ukić, Šime; Stankov, Mirjana Novak; Rogošić, Marko

    2017-07-01

    This study describes the development of tool for testing different policies for reduction of greenhouse gas (GHG) emissions in energy sector using artificial neural networks (ANNs). The case study of Croatia was elaborated. Two different energy consumption scenarios were used as a base for calculations and predictions of GHG emissions: the business as usual (BAU) scenario and sustainable scenario. Both of them are based on predicted energy consumption using different growth rates; the growth rates within the second scenario resulted from the implementation of corresponding energy efficiency measures in final energy consumption and increasing share of renewable energy sources. Both ANN architecture and training methodology were optimized to produce network that was able to successfully describe the existing data and to achieve reliable prediction of emissions in a forward time sense. The BAU scenario was found to produce continuously increasing emissions of all GHGs. The sustainable scenario was found to decrease the GHG emission levels of all gases with respect to BAU. The observed decrease was attributed to the group of measures termed the reduction of final energy consumption through energy efficiency measures.

  19. 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

    2014-04-07

    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.

  20. Application of Waste Heat Recovery Energy Saving Technology in Reform of UHP-EAF

    NASA Astrophysics Data System (ADS)

    Zhao, J. H.; Zhang, S. X.; Yang, W.; Yu, T.

    2017-08-01

    The furnace waste heat of a company’s existing 4 × 100t ultra-high-power electric arc furnaces is not used and discharged directly of the situation has been unable to meet the national energy-saving emission reduction requirements, and also affected their own competitiveness and sustainable development. In order to make full use of the waste heat of the electric arc furnace, this paper presents an the energy-saving transformation program of using the new heat pipe boiler on the existing ultra-high-power electric arc furnaces for recovering the waste heat of flue gas. The results show that after the implementation of the project can save energy equivalent to 42,349 tons of standard coal. The flue gas waste heat is fully utilized and dust emission concentration is accorded with the standard of Chinese invironmental protection, which have achieved good results.

  1. 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).

  2. Resonant and non-resonant energy transfer from Ce(3+)  → X (X = Tb(3)(+) , Eu(3)(+) or Dy(3)(+) ) in NaMgSO4 F material.

    PubMed

    Choubey, S R; Gedam, S C; Dhoble, S J

    2017-03-01

    An inorganic NaMgSO4 F fluoride material was prepared by the wet chemical method and studied for its photoluminescence (PL) and resonant-non-resonant energy transfer (RET and NORET) capabilities between Ce(3)(+)  → Tb(3)(+) , Ce(3)(+)  → Eu(3)(+) and Ce(3)(+)  → Dy(3)(+) rare earth ions. The Tb(3)(+) emission for Ce(3)(+)  → Tb(3)(+) transfers under ultraviolet (UV) wavelengths peaked at 491, 547, and 586 nm, for excitation at 308 nm due to (5) D4  → (7) FJ (J = 4, 5, 6) transitions. Eu emission spectra were observed at 440 nm (Eu(2)(+) ), 593 nm and 616 nm (Eu(3)(+) ) recorded for different concentrations of materials, whereas Dy(3)(+) emission from Ce(3)(+)  → Dy(3)(+) transfer under UV wavelengths peaked at 485 nm and 577 nm due to (4) F9/2  → (6) H15/2 and (6) H13/2 transitions. The purpose of the present study is to understand the RET and NORET effects of Tb(3)(+) , Eu(3)(+) and Dy(3)(+) co-doping in a NaMgSO4 F:Ce(3)(+) luminescent material, which could be used as a green-emitting material for lamp phosphors. Copyright © 2016 John Wiley & Sons, Ltd.

  3. 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.

  4. 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.

  5. Ca-α-SiAlON:Eu Phosphors: Oxidation States, Energy Transfer, and Emission Enhancement by Incorporation-Aimed Surface Engineering.

    PubMed

    Chen, Xiangyang; Gan, Lin; Zhang, Zhijun; Lu, Ping; Zeng, Xionghui; Zhang, Linlin; Yao, Heliang; Xu, Fangfang; Zhao, Jingtai

    2017-09-13

    Ca-α-SiAlON:Eu is one of the most promising phosphors exhibiting potential applications in high power LEDs owing to its excellent thermal stability and relatively high luminescence efficiency comparable to YAG:Ce commercial phosphors. The oxidation states of Eu ions in Ca-α-SiAlON:Eu are still questionable, and furthermore it exhibits lower luminescence intensity than commercial yellow phosphors. Therefore, in the present work, the valences of Eu ions in Ca-α-SiAlON have been examined, from which a mixture of divalence and trivalence is observed. Further improvement in emission intensity involves finding a way to increase the incorporation of larger Eu ions into the Ca-α-SiAlON. Here, we observed preferred doping of Eu around phosphor grain surface and then propose a surface engineering strategy involving HF pickling of glassy surface layer, formation of Eu-rich precursors, and finally post-annealing, aiming to increase surface incorporation of Eu ions. The surface engineered samples exhibit great enhancement in emission intensity with a maximum increment by 80%.

  6. 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.

  7. 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.

  8. 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.

  9. Pakistan oil, gas reforms tied to bid for energy self-sufficiency by 2000

    SciTech Connect

    Not Available

    1991-12-09

    This paper reports on oil and gas exploration and development which is accelerating in Pakistan as it seeks to achieve energy self-sufficiency by 2000. In addition to backing out some domestic oil use with burgeoning natural gas supplies and cutting refined products imports by boosting refining capacity, Pakistan is targeting a sharp increase in oil production. Ultimately, industry officials in Pakistan would like to see it become a significant net exporter of oil, perhaps qualifying it for eventual membership in the Organization of Petroleum Exporting Countries. And foreign investment will play a key role in that effort as the government takes steps to sweeten incentives for foreign oil and gas companies. Consequently, drilling activity and the number of foreign operated concessions are at record levels in Pakistan. Meantime, state owned Oil and Gas Development Corp. has embarked on an ambitious program of exploration in underexplored basins while seeking foreign assistance in hiking oil recovery rates in existing fields.

  10. 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.

  11. 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.

  12. The CERN-EU high-energy reference field (CERF) facility for dosimetry at commercial flight altitudes and in space.

    PubMed

    Mitaroff, A; Cern, M Silari

    2002-01-01

    A reference facility for the calibration and intercomparison of active and passive detectors in broad neutron fields has been available at CERN since 1992. A positively charged hadron beam (a mixture of protons and pions) with momentum of 120 GeV/c hits a copper target, 50 cm thick and 7 cm in diameter. The secondary particles produced in the interaction traverse a shield, at 90 degrees with respect to the direction of the incoming beam. made of either 80 to 160 cm of concrete or 40 cm of iron. Behind the iron shield, the resulting neutron spectrum has a maximum at about 1 MeV, with an additional high-energy component. Behind the 80 cm concrete shield, the neutron spectrum has a second pronounced maximum at about 70 MeV and resembles the high-energy component of the radiation field created by cosmic rays at commercial flight altitudes. This paper describes the facility, reports on the latest neutron spectral measurements, gives an overview of the most important experiments performed by the various collaborating institutions over recent years and briefly addresses the possible application of the facility to measurements related to the space programme.

  13. Study on Trap Levels in SrSi2AlO2N3:Eu(2+),Ln(3+) Persistent Phosphors Based on Host-Referred Binding Energy Scheme and Thermoluminescence Analysis.

    PubMed

    Zhuang, Yixi; Lv, Ying; Li, Ye; Zhou, Tianliang; Xu, Jian; Ueda, Jumpei; Tanabe, Setsuhisa; Xie, Rong-Jun

    2016-11-21

    We investigated the effect of trivalent lanthanide substitution on a novel oxynitride persistent phosphor SrSi2AlO2N3:Eu(2+),Ln(3+), which shows green persistent luminescence for more than 2 h. First, an energy level diagram by using the host-referred binding energy (HRBE) scheme was constructed. The location of the energy levels of all divalent and trivalent lanthanides referred to the energy band of the host SrSi2AlO2N3 was estimated. Then, thermoluminescence (TL) measurements in the target persistent phosphors were performed to obtain direct experimental results on the trap depth. We found that the trap levels based on the TL measurements coincided well with the 4f ground states of divalent lanthanide codopants in SrSi2AlO2N3:Eu(2+),Ln(3+). The result strongly suggests the effective traps for persistent luminescence in SrSi2AlO2N3:Eu(2+),Ln(3+) could be due to the aliovalent substitution of Ln(3+) for Sr(2+), which can be controlled by selecting suitable codopant Ln(3+). The work shows the HRBE scheme may offer a way to understand the nature of defects in the persistent phosphor as well as a possible guideline to design new persistent phosphors with required trap depths.

  14. An experimental study of the CO2-CH4 reforming-methanation cycle as a mechanism for converting and transporting solar energy

    NASA Astrophysics Data System (ADS)

    McCrary, J. H.; McCrary, G. E.; Chubb, T. A.; Nemecek, J. J.; Simmons, D. E.

    1982-01-01

    The CO2-CH4 reforming-methanation chemical cycle provides an attractive means of transporting solar energy to a central station in accord with the Solchem concept. A number of receiver elements (chemical reactors) have been tested in the laboratory in an effort to optimize the catalyst parameters and the catalyst-reactor configuration. These tests led to the design and fabrication of both prototype and full scale production model Solchem receivers which were operated successfully at the White Sands Solar Furnace. The development of energy delivery methanation reactors is proceeding along with the design of both laboratory and field-model closed-loop Solchem systems.

  15. Quadrupole splitting and Eu partial lattice dynamics in europium orthophosphate EuPO 4

    NASA Astrophysics Data System (ADS)

    Klobes, B.; Arinicheva, Y.; Neumeier, S.; Simon, R. E.; Jafari, A.; Bosbach, D.; Hermann, R. P.

    2016-12-01

    Hyperfine interactions in europium orthophosphate EuPO4 were investigated using 151Eu Mössbauer spectroscopy from 6 to 300 K. The value of the quadrupole splitting and the asymmetry parameter were refined and further substantiated by nuclear forward scattering data obtained at room temperature. The temperature dependence of the relative absorption was modeled with an Eu specific Debye temperature of 221(1) K. Eu partial lattice dynamics were probed by means of nuclear inelastic scattering and the mean force constant, the Lamb-Mössbauer factor, the internal energy, the vibrational entropy, the average phonon group velocity were calculated using the extracted density of phonon states. In general, Eu specific vibrations are characterized by rather small phonon energies and contribute strongly to the total entropy of the system. Although there is no classical Debye like behavior at low vibrational energies, the average phonon group velocity can be reasonably approximated using a linear fit.

  16. 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

  17. 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

    2016-06-07

    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.

  18. EU Cadzie project

    NASA Astrophysics Data System (ADS)

    Naaim, M.

    2009-04-01

    The CADZIE project received nearly € 700,000 funding under the energy, environment and sustainable development section of the Fifth Framework Programme (FP5). Several scientists from France, Italy, Norway, Austria, Iceland and Switzerland were involved in this initiative, under the co-ordination of the Cemagref institute in Grenoble, France. The initiative was created in response to the extreme avalanche winter of 1999, during which 83 people were killed across Europe. Avalanche protection relies on two key processes: structural measures such as building defence structures to stop and / or contain the avalanche flow and non structural measures such as zoning the exposed areas. The consortium investigated these two areas in order to improve overall protection methods. This EU-funded collaboration has led to the development of more accurate methods for mapping and protection design.

  19. Reforming catalysts

    SciTech Connect

    Givens, E.N.; Plank, C.J.; Rosinski, E.J.

    1980-03-04

    Crystalline aluminosilicate zeolites are mixed with conventional reforming catalysts to produce new catalytic compositions with high catalytic activity and selectivity and excellent aging characteristics. These new catalytic compositions may be utilized alone or in conjunction with conventional reforming catalysts. The acidic activity of the total catalyst system is controlled within defined limits. When so controlled the utility of these catalyst systems in reforming hydrocarbon mixtures is to reduce the C1 and C2 concentrations in reformer gas product, while increasing the C3 and C4 concentrations and maintaining high liquid yield at high octane numbers.

  20. Saturation Behavior of Eu ion emission in GaN

    NASA Astrophysics Data System (ADS)

    Hernandez, Natalie; Mitchell, Brandon; Fujiwara, Yasufumi; Dierolf, Volkmar

    Europium doped Gallium Nitride (GaN:Eu) has been recognized as a candidate for the red-emitting active layer in nitride-based light emitting diodes. To better comprehend the excitation energy transfer from the excited GaN host to the Eu ion, we performed an extensive analysis of GaN:Eu and GaN co-doped with Eu and other dopants (Silicon and Magnesium). We determined how various growth parameters manipulated site formations and measured the optical accessibility of the Eu ions within the GaN host and the excitation efficiency of the energy transfer between the host material and the Eu ions. Furthermore, we derived a model for the saturation behavior of the emission of Eu ions within GaN. Our results suggest that the saturation behavior is strongly influenced by different crystal growth specifications and co-dopants.

  1. Enhanced free energy of extraction of Eu(3+) and Am(3+) ions towards diglycolamide appended calix[4]arene: insights from DFT-D3 and COSMO-RS solvation models.

    PubMed

    Ali, Sk Musharaf

    2017-08-22

    Density functional theory in conjunction with COSMO and COSMO-RS solvation models employing dispersion correction (DFT-D3) has been applied to gain an insight into the complexation of Eu(3+)/Am(3+) with diglycolamide (DGA) and calix[4]arene appended diglycolamide (CAL4DGA) in ionic liquids by studying structures, energetics, thermodynamics and population analysis. The calculated Gibbs free energy for both Eu(3+) and Am(3+) ions with DGA was found to be smaller than that with CAL4DGA. The entropy of complexation was also found to be reduced to a large extent with DGA compared to complexation with CAL4DGA. The solution phase free energy was found to be negative and was higher for Eu(3+) ion. The entropy of complexation was not only found to be further reduced but also became negative in the case of DGA alone. Though the entropy was found to be negative it could not outweigh the high negative enthalpic contribution. The same trend was observed in the solution where the free energy of extraction, ΔG, for Eu(3+) ions was shown to be higher than that for Am(3+) ions towards free DGA. But the values of ΔG and ΔΔG(= ΔGEu-ΔGAm) were found to be much higher with CAL4DGA (-12.58 kcal mol(-1)) in the presence of nitrate ions compared to DGA (-1.69 kcal mol(-1)) due to enhanced electronic interaction and positive entropic contribution. Furthermore, both the COSMO and COSMO-RS models predict very close values of ΔΔΔG (= ΔΔGCAL4DGA - ΔΔGnDGA), indicating that both solvation models could be applied for evaluating the metal ion selectivity. The value of the reaction free energy was found to be higher after dispersion correction. The charge on the Eu and Am atoms for the complexes with DGA and CAL4DGA indicates the charge-dipole type interaction leading to strong binding energy. The present theoretical results support the experimental findings and thus might be of importance in the design of functionalized ligands.

  2. 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

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

    PubMed

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

    2015-01-19

    LiYF4:Eu nanophosphors with a single tetragonal phase are synthesized, and various strategies to enhance the Eu(3+) emission from the nanophosphors are investigated. The optimized Eu(3+) concentration is 35 mol%, and the red emission peaks due to the (5)D0 →(7)FJ (J = 1 and 2) transitions of Eu(3+) ions are further enhanced by energy transfer from a sensitizer pair of Ce(3+) and Tb(3+). The triple doping of Ce, Tb, and Eu into the LiYF4 host more effectively enhances the Eu(3+) 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 Ce(3+) to Eu(3+) through Tb(3+) results in three times higher Eu(3+) emission intensity from LiYF4:Ce(15%), Tb(15%), Eu(1%) nanophosphors compared with LiYF4:Eu(35%), which contains the optimized Eu(3+) concentration. Owing to the energy transfer of Ce(3+) → Tb(3+) and Ce(3+) → Tb(3+) → Eu(3+), 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 Eu(3+) concentration. With increasing Eu(3+) 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. 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…

  6. 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…

  7. Russia’s Future Energy Policies: A Glimpse of Moscow’s Impact on EU and US Energy Security in 2025

    DTIC Science & Technology

    2009-04-01

    Graduation Requirements Advisor: Dr. John T. Ackerman Maxwell Air Force Base, Alabama April 2009 Report Documentation Page Form ApprovedOMB No. 0704...4.0. Summary of results – scenario-thinking model ………………………………........ 23 v Acknowledgment I would like to acknowledge Dr. John ...champions. Andrew Monaghan , author of Russia and the Security of Europe’s Energy Supplies: Security in Diversity, argues the lack of unity gives

  8. 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%.

  9. Educational Reform.

    ERIC Educational Resources Information Center

    Winter, Janet

    The need exists for educational reform. Student achievement scores are down, unemployment and dropout rates are up, social and welfare costs are up, economic productivity has declined, and shortages of qualified teachers are imminent. After Chapter 1 of this paper provides background and history for school reform, Chapter 2 reviews the literature,…

  10. Luminescence properties and energy transfer of site-sensitive Ca(6-x-y)Mg(x-z)(PO(4))(4):Eu(y)(2+),Mn(z)(2+) phosphors and their application to near-UV LED-based white LEDs.

    PubMed

    Kwon, Ki Hyuk; Im, Won Bin; Jang, Ho Seong; Yoo, Hyoung Sun; Jeon, Duk Young

    2009-12-21

    On the basis of the structural information that the host material has excellent charge stabilization, blue-emitting Ca(6-x-y)Mg(x)(PO(4))(4):Eu(y)(2+) (CMP:Eu(2+)) phosphors were synthesized and systematically optimized, and their photoluminescence (PL) properties were evaluated. Depending upon the amount of Mg added, the emission efficiency of the phosphors could be enhanced. The substitution of Eu(2+) affected their maximum wavelength (lambda(max)) and thermal stability because the substitution site of Eu(2+) could be varied. To obtain single-phase two-color-emitting phosphors, we incorporated Mn(2+) into CMP:Eu(2+) phosphors. Weak red emission resulting from the forbidden transition of Mn(2+) could be enhanced by the energy transfer from Eu(2+) to Mn(2+) that occurs because of the spectral overlap between the photoluminescence excitation (PLE) spectrum of Mn(2+) and the PL spectrum of Eu(2+). The energy transfer process was confirmed by the luminescence spectra, energy transfer efficiency, and decay curve of the phosphors. Finally, the optimized Ca(6-x-y)Mg(x-z)(PO(4))(4):Eu(y)(2+),Mn(z)(2+) (CMP:Eu(2+),Mn(2+)) phosphors were applied with green emitting Ca(2)MgSi(2)O(7):Eu(2+) (CMS:Eu(2+)) phosphors to ultraviolet (UV) light emitting diode (LED)-pumped white LEDs. The CMS:Eu(2+)-mixed CMP:Eu(2+), Mn(2+)-based white LEDs showed an excellent color rendering index (CRI) of 98 because of the broader emission band and more stable color coordinates than those of commercial Y(3)Al(5)O(12):Ce(3+) (YAG:Ce(3+))-based white LEDs under a forward bias current of 20 mA. The fabricated white LEDs showed very bright natural white light that had the color coordinate of (0.3288, 0.3401), and thus CMP:Eu(2+),Mn(2+) could be regarded as a good candidate for UV LED-based white LEDs.

  11. 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.

  12. 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.

  13. Superfund reform: US Environmental Protection Agency`s 30-day study and its implication for the US Department of Energy

    SciTech Connect

    Siegel, M.R.; Friedman, J.R.; Neff, R.W.

    1993-03-01

    As part of an ongoing effort to reform and restructure the US Environmental Protection Agency`s (EPAS) Superfund program, the EPA Administrator on October 21, 1991, announced several key programmatic reforms. These reforms are a result of the Superfund 30-Day Task Force Report (30-Day Study, EPA 1991a), an effort carried out by EPAs office of Solid Waste and Emergency Response (OSWER). The EPA OSWER oversees environmental cleanup activities under a number of statutory authorities, including the Comprehensive Environmental response, Compensation, and Liability Act (CERCLA, also known as Superfund). CERCLA and its implementing regulation, the National Contingency Plan (NCP), establish a regulatory framework to govern the cleanup of existing, and often abandoned, hazardous waste sites. The purposes of this report are to (1) review the background and recommendations of EPNs 30-Day Study, (2) identify and discuss the initiatives from the 30-Day Study that may impact DOE`s environmental restoration mission, (3) report on EPAs progress in implementing the selected priority initiatives, and (4) describe potentially related DOE activities.

  14. Catalytic reforming

    SciTech Connect

    Aldag, A.W. Jr.

    1986-01-28

    This patent describes a process for the catalytic reforming of a feedstock which contains at least one reformable organic compound. The process consists of contacting the feedstock under suitable reforming conditions with a catalyst composition selected from the group consisting of a catalyst. The catalyst essentially consists of zinc oxide and a spinel structure alumina. Another catalyst consists essentially of a physical mixture of zinc titanate and a spinel structure alumina in the presence of sufficient added hydrogen to substantially prevent the formation of coke. Insufficient zinc is present in the catalyst composition for the formation of a bulk zinc aluminate.

  15. Reforming process

    SciTech Connect

    Mitsche, R.T.; Pope, G.N.

    1981-01-06

    A process for reforming a naphtha feedstock is disclosed. The reforming process is effected at reforming conditions in contact with a catalyst comprising a platinum group metal component and a group iv-a metal component composited with an alumina support wherein said support is prepared by admixing an alpha alumina monohydrate with an aqueous ammoniacal solution having a ph of at least about 7.5 to form a stable suspension. A salt of a strong acid, e.g., aluminum nitrate, is commingled with the suspension to form an extrudable paste or dough. On extrusion, the extrudate is dried and calcined to form said alumina support.

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

    PubMed

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

    2016-06-27

    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.

  17. 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

  18. 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.

  19. Analysis of healthcare financing, supply and utilisation trends in the new EU countries.

    PubMed

    Ruseski, Jane E

    2006-01-01

    The EU expanded in 2004 to include eight transition countries, i.e. Central and Eastern European (CEE) and newly independent states of the former Soviet Union, and two other CEE countries are scheduled to join the EU in 2007. Each of these countries has undertaken substantial healthcare reform efforts over the past 15 years. The paths of healthcare reform are diverse for a number of reasons including differences in initial economic, political and structural conditions. The objective of this article is to evaluate the process and preliminary outcomes of healthcare reform in the new EU and candidate countries by analysing trends in aggregate financing, supply and utilisation indicators using data drawn from the WHO Health for All database. The analysis is done in the context of an analytical framework built around common healthcare reform themes. The key reform measures examined include implementing social insurance systems, implementing payment systems that promote efficiency, and removal of excess capacity. The trend analysis highlights the importance of the economic, political and social context in driving the direction and pace of healthcare reform. For example, the transition to social insurance systems was smoother in countries with stronger economies and political commitment to reform. Policies aimed at improving the efficiency of the healthcare system, reducing utilisation and reducing excess capacity were met with some success in all of the countries. However, the reform effort continues as the countries are still addressing the initial challenges of insufficient funding, informal payments, excess capacity and inefficiencies in the provision of healthcare.

  20. Syntheses, structures, and sensitized lanthanide luminescence by Pt --> Ln (Ln = Eu, Nd, Yb) energy transfer for heteronuclear PtLn2 and Pt2Ln4 complexes with a terpyridyl-functionalized alkynyl ligand.

    PubMed

    Li, Xiu-Ling; Shi, Lin-Xi; Zhang, Li-Yi; Wen, Hui-Min; Chen, Zhong-Ning

    2007-12-10

    Reaction of Pt(dppm-P,P')Cl2 (dppm = 1,2-bis(diphenylphosphino)methane) with HCCPhtpy (HCCPhtpy = 4'-(4-ethynylphenyl)-2,2':6',2"-terpyridine) in the presence of copper(I) iodide and diisopropylamine induced isolation of mononuclear complex cis-Pt(dppm-P,P')(C[triple bond]CPhtpy)2 (1), which can be converted into face-to-face diplatinum(II) species Pt2(mu-dppm)2(C[triple bond]CPhtpy)4 (5) when equivalent dppm is added. Incorporating 1 or 5 to Ln(hfac)3(H2O)2 (Hhfac = hexafluoroacetylacetone) gave PtLn2 (Ln = Nd (2), Eu (3), Yb (4)) or Pt2Ln4 (Ln = Nd (6), Eu (7), Gd (8), Yb (9)) adducts with the lanthanide centers chelated by terdentate terpyridyl in the bridging C[triple bond]CPhtpy. The structures of 1, 6, 7, and 9 were determined by X-ray crystallography. Upon excitation at lambdaex = 360-450 nm (2-4) or 360-500 nm (6-9), where the PtII alkynyl antenna chromophores absorb strongly but the model complexes Ln(hfac)3(HC[triple bond]CPhtpy) lack obvious absorption in this region, these PtLn2 and Pt2Ln4 (Ln = Nd, Eu, Yb) species exhibit band-like lanthanide luminescence that is typical of the corresponding Ln3+ ions, demonstrating unambiguously that efficient Pt --> Ln energy transfer occurs indeed from the PtII alkynyl antenna chromophores to the lanthanide centers across the bridging CCPhtpy with intramolecular Pt...Ln distances being ca. 14.2 A. The Pt --> Ln energy transfer rate (kET) is 6.07 x 10(7) s(-1) for Pt2Nd4 (6) and 2.12 x 10(5) s(-1) for Pt2Yb4 (9) species.

  1. 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.

  2. Evidence of Eu2+ 4f electrons in the valence band spectra of EuTiO3 and EuZrO3

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    We report on optical band gap and valence electronic structure of two Eu2+-based perovskites, EuTiO3 and EuZrO3 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 4f7 electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO3 perovskites except that it is shifted to higher binding energies. Appearance of the Eu2+ 4f7 band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  3. Fermi Surface Properties of Eu-Divalent and Eu-Trivalent Electronic States with the AuCu3-type Cubic Structure

    NASA Astrophysics Data System (ADS)

    Nakamura, Ai; Takeuchi, Tetsuya; Tatetsu, Yasutomi; Maehira, Takahiro; Harima, Hisatomo; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2015-03-01

    The electronic states in EuBi3 and EuPd3 are known to be Eu-divalent and Eu- trivalent, respectively, from the previous studies using polycrystal samples. In the present study, we succeeded in growing high-quality single crystals, and carried out the de Haas-van Alphen (dHvA) measurements and energy band calculations to clarify the Fermi surface properties.

  4. Naphtha reforming

    SciTech Connect

    Marschner, F.; Renner, H.J.

    1982-04-01

    Most synthesis gases - mixtures of CO and H/sub 2/ - are produced from natural gas. However, a considerable percentage is also produced from naphtha. Syngas via naphtha is economical when natural gas is unavailable and when low hydrogen content syngas is needed. The discussion covers the following topics - catalytic steam reforming; naphtha qualities; process description; desulfurization reactors; rich gas reactors; tubular reactors; fire box; burner and firing systems; reformer tubes; inlet header and outlet manifold systems; waste heat systems, heat exchangers, piping. 10 refs.

  5. 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.

  6. 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.

  7. Slab reformer

    DOEpatents

    Spurrier, F.R.; DeZubay, E.A.; Murray, A.P.; Vidt, E.J.

    1984-02-07

    Slab-shaped high efficiency catalytic reformer configurations are disclosed 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. 14 figs.

  8. 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.

  9. Slab reformer

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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 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.

  10. Reform Evaluation.

    ERIC Educational Resources Information Center

    Yoloye, E. Ayotunde

    1981-01-01

    Focuses on issues in evaluating educational change. Topics include what should be evaluated, management of reform and evaluation, evaluation as a threat, attitudes toward evaluation, factors in drawing up an evaluation plan, management information systems, evaluation techniques, financing evaluation, and indicators of success. (KC)

  11. 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.…

  12. 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,…

  13. 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.…

  14. Energy-water-food nexus under financial constraint environment: good, the bad, and the ugly sustainability reforms in sub-Saharan African countries.

    PubMed

    Zaman, Khalid; Shamsuddin, Sadaf; Ahmad, Mehboob

    2017-04-06

    Environmental sustainability agenda are generally compromised by energy, water, and food production resources, while in the recent waves of global financial crisis, it mediates to increase the intensity of air pollutants, which largely affected the less developing countries due to their ease of environmental regulation policies and lack of optimal utilization of economic resources. Sub-Saharan African (SSA) countries are no exception that majorly hit by the recent global financial crisis, which affected the country's natural environment through the channel of unsustainable energy-water-food production. The study employed panel random effect model that addresses the country-specific time-invariant shocks to examine the non-linear relationship between water-energy-food resources and air pollutants in a panel of 19 selected SSA countries, for a period of 2000-2014. The results confirmed the carbon-fossil-methane environmental Kuznets curve (EKC) that turned into inverted U-shaped relationships in a panel of selected SSA countries. Food resources largely affected greenhouse gas (GHG), methane (CH4), and nitrous oxide (N2O) emissions while water resource decreases carbon dioxide (CO2), fossil fuel, and CH4 emissions in a region. Energy efficiency improves air quality indicators while industry value added increases CO2 emissions, fossil fuel energy, and GHG emissions. Global financial crisis increases the risk of climate change across countries. The study concludes that although SSA countries strive hard to take some "good" initiatives to reduce environmental degradation in a form of improved water and energy sources, however, due to lack of optimal utilization of food resources and global financial constraints, it leads to "the bad" and "the ugly" sustainability reforms in a region.

  15. Reforming catalyst

    SciTech Connect

    Baird, W.C. Jr.; Swan, G.A.

    1991-11-19

    This patent describes a catalyst useful for reforming a naphtha feed at high severity reforming conditions. It comprises the metals, platinum, rhenium and iridium on a refractory porous inorganic oxide support, the support consisting essentially of alumina, wherein the concentration by weight of each of the metals platinum and rhenium is at least 0.1 percent and iridium at least 0.15 percent and at least one of the metals is present in a concentration of at least 0.3 percent, and the sum-total; concentration of the metals is greater than 0.9 percent, and wherein each catalyst particle contains all three of the metals platinum, rhenium and iridium. This patent also describes this composition wherein the catalyst contains from about 0.1 percent to about 3 percent of a halogen and from about 0.05 percent to about 0.02 percent sulfur.

  16. Horizon 2020 EuPRAXIA design study

    NASA Astrophysics Data System (ADS)

    Walker, P. A.; Alesini, P. D.; Alexandrova, A. S.; Anania, M. P.; E Andreev, N.; Andriyash, I.; Aschikhin, A.; Assmann, R. W.; Audet, T.; Bacci, A.; Barna, I. F.; Beaton, A.; Beck, A.; Beluze, A.; Bernhard, A.; Bielawski, S.; Bisesto, F. G.; Boedewadt, J.; Brandi, F.; Bringer, O.; Brinkmann, R.; Bründermann, E.; Büscher, M.; Bussmann, M.; Bussolino, G. C.; Chance, A.; Chanteloup, J. C.; Chen, M.; Chiadroni, E.; Cianchi, A.; Clarke, J.; Cole, J.; E Couprie, M.; Croia, M.; Cros, B.; Dale, J.; Dattoli, G.; Delerue, N.; Delferriere, O.; Delinikolas, P.; Dias, J.; Dorda, U.; Ertel, K.; Ferran Pousa, A.; Ferrario, M.; Filippi, F.; Fils, J.; Fiorito, R.; Fonseca, R. A.; Galimberti, M.; Gallo, A.; Garzella, D.; Gastinel, P.; Giove, D.; Giribono, A.; Gizzi, L. A.; Grüner, F. J.; Habib, A. F.; Haefner, L. C.; Heinemann, T.; Hidding, B.; Holzer, B. J.; Hooker, S. M.; Hosokai, T.; Irman, A.; Jaroszynski, D. A.; Jaster-Merz, S.; Joshi, C.; Kaluza, M. C.; Kando, M.; Karger, O. S.; Karsch, S.; Khazanov, E.; Khikhlukha, D.; Knetsch, A.; Kocon, D.; Koester, P.; Kononenko, O.; Korn, G.; Kostyukov, I.; Labate, L.; Lechner, C.; Leemans, W. P.; Lehrach, A.; Y Li, F.; Li, X.; Libov, V.; Lifschitz, A.; Litvinenko, V.; Lu, W.; Maier, A. R.; Malka, V.; Manahan, G. G.; Mangles, S. P. D.; Marchetti, B.; Marocchino, A.; Martinez de la Ossa, A.; Martins, J. L.; Massimo, F.; Mathieu, F.; Maynard, G.; Mehrling, T. J.; Y Molodozhentsev, A.; Mosnier, A.; Mostacci, A.; Mueller, A. S.; Najmudin, Z.; Nghiem, P. A. P.; Nguyen, F.; Niknejadi, P.; Osterhoff, J.; Papadopoulos, D.; Patrizi, B.; Pattathil, R.; Petrillo, V.; Pocsai, M. A.; Poder, K.; Pompili, R.; Pribyl, L.; Pugacheva, D.; Romeo, S.; Rossi, A. R.; Roussel, E.; Sahai, A. A.; Scherkl, P.; Schramm, U.; Schroeder, C. B.; Schwindling, J.; Scifo, J.; Serafini, L.; Sheng, Z. M.; Silva, L. O.; Silva, T.; Simon, C.; Sinha, U.; Specka, A.; Streeter, M. J. V.; Svystun, E. N.; Symes, D.; Szwaj, C.; Tauscher, G.; Thomas, A. G. R.; Thompson, N.; Toci, G.; Tomassini, P.; Vaccarezza, C.; Vannini, M.; Vieira, J. M.; Villa, F.; Wahlström, C.-G.; Walczak, R.; Weikum, M. K.; Welsch, C. P.; Wiemann, C.; Wolfenden, J.; Xia, G.; Yabashi, M.; Yu, L.; Zhu, J.; Zigler, A.

    2017-07-01

    The Horizon 2020 Project EuPRAXIA (“European Plasma Research Accelerator with eXcellence In Applications”) is preparing a conceptual design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020.

  17. 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.

  18. Thermodynamic Assessment of EuCl3-MgCl2 and EuCl3-BaCl2 Systems

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Sun, Yimin

    2011-09-01

    Using the CALPHAD technique, an assessment of the binary EuCl3-MgCl2 and EuCl3-BaCl2 systems has been carried out in this study. The modified quasi-chemical model was defined to describe the Gibbs energies of the liquid phases, and the model parameters were optimized from the experimental phase diagram data. The phase diagrams and enthalpies of mixing of the EuCl3-MgCl2 and EuCl3-BaCl2 systems were calculated. The calculated results by the present method agree well with the experimental data. The Gibbs energies of formation of Mg3Eu2Cl12, Ba3Eu2Cl12, and Ba2Eu3Cl13 from the pure components were predicted.

  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. 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.

  1. 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

    2016-08-03

    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

  2. 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.

  3. 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…

  4. 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.

  5. 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.

  6. Tunable luminescence and enhanced photocatalytic activity for Eu(III) doped Bi2WO6 nanoparticles

    NASA Astrophysics Data System (ADS)

    Gu, Haidong; Yu, Lei; Wang, Juan; Ni, Min; Liu, Tingting; Chen, Feng

    2017-04-01

    A series of Eu(III) doped Bi2WO6 nanoparticles were synthesized by a hydrothermal process. The obtained Bi2WO6:Eu(III) nanoparticles were characterized by XRD, SEM, luminescence spectrophotometer and DRS. The XRD and TEM results indicate that the Eu(III) doping concentration has no influence on the phase and morphology. However, the Eu(III) doping can tune the luminescence and enhance the photocatalytic activity of Bi2WO6. With the increases of Eu3 + doping concentrations, the emission intensity of WO66 - group decreases nut the photocatalytic activity increases. The tunable luminescence of Bi2WO6:Eu(III) nanoparticles results from the energy transfer from WO66 - group to Eu(III) ion. The enhanced performance can be ascribed to efficient separation of electron and hole pairs after doping Eu(III) into the Bi2WO6 lattice.

  7. Tunable luminescence and enhanced photocatalytic activity for Eu(III) doped Bi2WO6 nanoparticles.

    PubMed

    Gu, Haidong; Yu, Lei; Wang, Juan; Ni, Min; Liu, Tingting; Chen, Feng

    2017-04-15

    A series of Eu(III) doped Bi2WO6 nanoparticles were synthesized by a hydrothermal process. The obtained Bi2WO6:Eu(III) nanoparticles were characterized by XRD, SEM, luminescence spectrophotometer and DRS. The XRD and TEM results indicate that the Eu(III) doping concentration has no influence on the phase and morphology. However, the Eu(III) doping can tune the luminescence and enhance the photocatalytic activity of Bi2WO6. With the increases of Eu(3+) doping concentrations, the emission intensity of WO6(6-) group decreases nut the photocatalytic activity increases. The tunable luminescence of Bi2WO6:Eu(III) nanoparticles results from the energy transfer from WO6(6-) group to Eu(III) ion. The enhanced performance can be ascribed to efficient separation of electron and hole pairs after doping Eu(III) into the Bi2WO6 lattice.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The anion photoelectron (PE) spectra of EuH- and the PE spectrum of overlapping EuOH- and EuO- 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 8Σ- anion ground states arising from the 4f7σ6s2 superconfiguration to the close-lying neutral 9Σ- and 7Σ- states arising from the 4f7σ6s superconfiguration are observed spaced by an energy interval similar to the free Eu+ [4f76s] 9S - 7S 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- photodetachment is complicated by the likely presence of two energetically competitive electronic states of EuO- populating the ion beam. However, based on the calculated relative energies of the close-lying anion states arising from the 4f7σ6s and 4f6σ6s2 configurations and the relative energies of the one-electron accessible 4f7 and 4f6σ6s 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 4f6σ6s2 7Σ- and 4f7σ6s7Σ- 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 4f6 occupancy.

  9. 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.

  10. Colour tuning and energy transfer pathways in MgAl2O4 triply doped with 0.1% Ce3+, 0.1% Eu2+, x% Tb3+ (0 ⩽ x ⩽ 2 %) nanocrystals synthesized using sol-gel process

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    A series of the undoped, 0.1% Ce3+, 0.1% Eu2+, 0.1% Tb3+ singly doped and 0.1% Ce3+, 0.1% Eu2+, x% Tb3+ (0 ⩽ x ⩽ 2 %) triply doped MgAl2O4 nanophosphors were synthesized by the sol-gel technique and thereafter annealed at 800 °C. The nanocrystals consist of the pure cubic structures. The type of the dopant and varying the Tb3+ mol% influence the crystallites size and morphology of the prepared powders. Photoluminescence (PL) results showed a red emission from Ce3+ singly doped MgAl2O4. Furthermore, the PL results revealed the existence of the energy transfer from Eu2+ → Tb3+ → Ce3+. CIE colour chromaticity showed that the colour can be tuned from bluish → greenish by changing the Tb3+ mol% and the excitation wavelength.

  11. 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.

  12. 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…

  13. [Experimental study on the Eu isotopic enrichment].

    PubMed

    Huang, Xue-ren; Zhong, Da; Mei, Gang-hua; Zhu, Xi-wen

    2002-10-01

    The polarized atomic beam has found many applications, such as in studying atomic scattering processes, producing polarized nucleus, verifying the parity principle, measuring surface parameters and enriching isotopes. In this paper, we mainly described the experiment of Eu isotope enrichment by means of magnetic deflection. According to the special inner energy level structure of Eu atom, we analyzed the theory of the polarized atomic beam and described the main experimental set-up. Using one coherent laser with the wavelength of 601.9 nm and sigma polarization, Eu153 atoms have been selectively optical pumped and polarized, so positive and negative polarized atomic beams could be produced. The polarized atomic beams have been focused and defocused after passing through the deflection by hex-magnet. Finally, some clear enrichmental signal has been obtained in way of hot-wire detection. During the process of the experiment, we carefully selected the optimized conditions, the Eu153 enrichment effect of 4% can be achieved using only one coherent laser.

  14. 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 help…

  15. 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 help…

  16. 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.

  17. Enhanced red luminescence in Gd2O3:Eu3+,Sm3+ and its dependence on temperature

    NASA Astrophysics Data System (ADS)

    Wu, Xiaofeng; Hu, Shigang; Tan, Congbing; Liu, Yunxin

    2014-10-01

    Here, we show that co-activation in the Gd3+-Eu3+-Sm3+ system can generate the intense red emission from Eu3+ ion. Gd2O3:Sm3+,Eu3+ colloidal spheres were synthesized by combining a low temperature hydrothermal process and a higher temperature of pyrolysis. Under the excitation of 380 nm near UV light, Gd2O3:Sm3+,Eu3+ emits intense red light while the reference Gd2O3:Eu3+ emits very weak one. The calculated polarizability αbμ based on the shift (16 nm) of Eu3+-O2- charge transfer band and the crystallography analysis revealed that Sm3+ ions codoping in Gd2O3:Eu3+ has generated a coordinating environment of Eu3+ ions with high polarizability and low symmetry which leads to high energy transfer rate not only between Sm3+ and Eu3+ pairs, but also between Eu3+(S6) and Eu3+(C2) pairs, ensuring the efficient excitation of Gd2O3:Eu3+,Sm3+. The energy migration from Sm3+ to Eu3+ and a corresponding feedback were also experimentally evidenced by the fluorescent decay, which is in well agreement with the theoretical calculation. In addition, the thermal stability of the photoluminescence in Gd2O3:Eu3+,Sm3+ colloidal spheres was evaluated.

  18. 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

  19. Hyper-stable organo-Eu(III) luminophore under high temperature for photo-industrial application.

    PubMed

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

    2016-04-14

    Novel organo-Eu(III) 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 Eu(III) 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 Eu(III) 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.

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

    DOE PAGES

    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

  1. 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"…

  2. 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"…

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. China's Health Reform Update.

    PubMed

    Liu, Gordon G; Vortherms, Samantha A; Hong, Xuezhi

    2017-03-20

    China experienced both economic and epistemological transitions within the past few decades, greatly increasing demand for accessible and affordable health care. These shifts put significant pressure on the existing outdated, highly centralized bureaucratic system. Adjusting to growing demands, the government has pursued a new round of health reforms since the late 2000s; the main goals are to reform health care financing, essential drug policies, and public hospitals. Health care financing reform led to universal basic medical insurance, whereas the public hospital reform required more complex measures ranging from changes in regulatory, operational, and service delivery settings to personnel management. This article reviews these major policy changes and the literature-based evidence of the effects of reforms on cost, access, and quality of care. It then highlights the outlook for future reforms. We argue that a better understanding of the unintended consequences of reform policies and of how practitioners' and patients' interests can be better aligned is essential for reforms to succeed.

  10. Startup procedure for reforming catalysts

    SciTech Connect

    McHale, W.D.; Schoennagel, H.J.

    1984-08-14

    Process for reforming a hydrocarbon charge under reforming conditions in a reforming zone containing a sulfur-sensitive metal containing reforming catalyst wherein over-cracking of the charge stock and excessive temperature rise in the reforming zone is suppressed by pre-conditioning the catalyst, prior to contact with the charge, with a reformate of specified octane number and aromatics content.

  11. 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…

  12. 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)

  13. 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…

  14. Time for Reform.

    ERIC Educational Resources Information Center

    Policy Brief, 1993

    1993-01-01

    Parents, teachers, and government officials agree that America's schools must be reformed. However, new research suggests that most reforms will not work without closer attention to one critical resource--time. This document presents findings of a study conducted by the Rand Institute on Education and Training, which found that any reform takes…

  15. History and Educational Reform.

    ERIC Educational Resources Information Center

    Hampel, Robert L.; And Others

    1996-01-01

    Features comments from Robert L. Hampel, William R. Johnson, Diane Ravitch, and David N. Plank on David Tyack and Larry Cuban's book, "Tinkering toward Utopia: A Century of Public School Reform." The book argues that educational reformers in the 20th century have attempted large-scale systemic reforms instituted from the top down. (MJP)

  16. School Reform Resource Manual.

    ERIC Educational Resources Information Center

    Mid-Continent Research for Education and Learning, Aurora, CO.

    This manual is designed to help schools make successful school reform a reality. It provides the background and perspectives necessary for a school constituency to understand the current climate of education reform in the United States and what is known about successful school reform. The manual also provides inquiry-based techniques for…

  17. History and Educational Reform.

    ERIC Educational Resources Information Center

    Hampel, Robert L.; And Others

    1996-01-01

    Features comments from Robert L. Hampel, William R. Johnson, Diane Ravitch, and David N. Plank on David Tyack and Larry Cuban's book, "Tinkering toward Utopia: A Century of Public School Reform." The book argues that educational reformers in the 20th century have attempted large-scale systemic reforms instituted from the top down. (MJP)

  18. 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)

  19. 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,…

  20. 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

  1. Focused Reform.

    ERIC Educational Resources Information Center

    Chesley, Gary M.; Jordan, Janice M.

    1996-01-01

    In "The Discipline of Market Leaders" (1995), Michael Treacy and Fred Wiersama argue that an enterprise cannot be successful unless it actively pursues one of three value propositions: operational leadership, customer intimacy, or product leadership. Schools, too, must make a strategic decision to devote energies, policies, and practices…

  2. Density-functional study of structural, electronic, and magnetic properties of the EuSin (n=1-13) clusters

    NASA Astrophysics Data System (ADS)

    Zhao, Gao-feng; Sun, Jian-min; Gu, Yu-zong; Wang, Yuan-xu

    2009-09-01

    The geometries, stabilities, and electronic and magnetic properties of europium encapsulated EuSin (n =1-13) clusters have been investigated systematically by using relativistic density functional theory with generalized gradient approximation. Starting from n =12, the Eu atom completely falls into the center of the Si frame, i.e., EuSi12 is the smallest fully endohedral Eu silicon cluster. The interesting finding is in good agreement with the recent experimental results on the photoelectron spectroscopy of the europium silicon clusters [A. Grubisic, H. P. Wang, Y. J. Ko, and K. H. Bowen, J. Chem. Phys. 129, 054302 (2008)]. The magnetic moments of the EuSin (n =1-13) clusters are also studied, and the results show that the total magnetic moments of the EuSin clusters and the magnetic moments on Eu do not quench when the Eu is encapsulated in the Si outer frame cage. It is concluded that most of the 4f electrons of the Eu atom in the EuSi12 cluster do not interact with the silicon cage and the total magnetic moments are overwhelming majority contributed by the 4f electrons of the Eu atom. According to the binding energy per atom, the second difference in energy (Δ2E), and vertical ionization potential, the EuSin (n =4,9,12) clusters are very stable.

  3. Radiation stability of CsBr:Eu needle image plates

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    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 Eu2+-containing precursor CsEuBr3 for the doping in the manufacturing process.

  4. 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.

  5. 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.

  6. New EU regulations in endoscopy.

    PubMed

    Wächter, M; Diekjobst, T

    1995-09-01

    As a result of European unification, new regulations valid within the territory of the European Union (EU) have been negotiated and published. As in other medical fields, the Medical Device Directive (MDD) is the most important new regulation and also effects endoscopy. In a transition period until June 1998, the MDD will be transposed into national law by the member states of the EU. Compliance with the MDD and other European regulations is indicated by the CE mark affixed to the product.

  7. 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.

  8. Quasiparticle bandstructure of antiferromagnetic EuTe

    NASA Astrophysics Data System (ADS)

    Mathi Jaya, S.; Nolting, W.

    1997-11-01

    The temperature-dependent electronic quasiparticle spectrum of the antiferromagnetic semiconductor EuTe is derived by use of a combination of a many-body model procedure with a tight-binding - `linear muffin tin orbital' (TB - LMTO) band structure calculation. The central part is the d - f model for a single band electron (`test electron') being exchange coupled to the antiferromagnetically ordered localized moments of the Eu ions. The single-electron Bloch energies of the d - f model are taken from a TB - LMTO calculation for paramagnetic EuTe. The d - f model is evaluated by a recently proposed moment conserving Green function technique to get the temperature-dependent sublattice - quasiparticle bandstructure (S - QBS) and sublattice - quasiparticle density of states (S - QDOS) of the unoccupied 5d - 6s energy bands. Unconventional correlation effects and the appearance of characteristic quasiparticles (`magnetic polarons') are worked out in detail. The temperature dependence of the S - QDOS and S - QBS is mainly provoked by the spectral weights of the energy dispersions. Minority- and majority-spin spectra coincide for all temperatures but with different densities of states. Upon cooling from 0953-8984/9/47/012/img1 to T = 0 K the lower conduction band edge exhibits a small blue shift of -0.025 eV in accordance with the experiment. Quasiparticle damping manifesting itself in a temperature-dependent broadening of the spectral density peaks arises from spin exchange processes between (5d - 6s) conduction band electrons and localized 4f moments.

  9. 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.

  10. Solid state synthesis of CaTiO3:Dy3+/Eu3+ phosphors towards white light emission

    NASA Astrophysics Data System (ADS)

    Li, Fei; Liu, Xu; He, Tao

    2017-10-01

    CaTiO3:Dy3+/Eu3+ phosphors were synthesized by a solid state reaction. The XRD and FTIR results demonstrate the single phase of the CaTiO3:Dy3+/Eu3+ phosphors. The overlap between the emission spectrum of Dy3+ and the excitation spectrum of Eu3+ suggests possible energy transfer from Dy3+ to Eu3+. And the energy transfer was confirmed by the decreasing Dy3+ emission intensity and lifetime with the increasing Eu3+ concentration. The comparable emission intensities of blue, yellow and red emissions for CaTiO3:Dy3+/Eu3+ phosphors mean that a possibility for the generation of white light by designing the concentrations of Dy3+ and Eu3+.

  11. Eu(3+) -doped polystyrene and polyvinylidene fluoride nanofibers made by electrospinning for photoluminescent fabric designing.

    PubMed

    Itankar, Sangeeta Gopichandra; Dandekar, Manjusha Prafulla; Kondawar, Subhash Baburao; Bahirwar, Bhaskar Marotrao

    2017-06-21

    Eu(3+) -doped polystyrene and polyvinylidene fluoride (PVDF/Eu(3+) and PS/Eu(3+) ) nanofibers were made using electrospinning. These fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDX) and photoluminescence (PL). Spectral analysis of PVDF/Eu(3+) and PS/Eu(3+) nanofibers was based on their emission spectra. A bright red emission was noticed from Eu(3+) that was assigned to the hypersensitive (5) D0  → (7) F2 transition. The enhanced intensity ratios of (5) D0  → (7) F2 to (5) D0  → (7) F1 transitions in the nanofibers indicated a more polarized chemical environment for the Eu(3+) ions and greater hypersensitivity for the (5) D0  → (7) F2 transition, which showed the potential for application in various polymer optoelectronic devices. The Eu(3+) -doped polymer (PVDF/Eu(3+) and PS/Eu(3+) ) nanofibers are suitable for the photoluminescent white light fabric design of smart textiles. This paper focuses on the potential application of smart fabrics to address challenges in human life. Copyright © 2017 John Wiley & Sons, Ltd.

  12. Synthesis, X-ray Structure, Spectroscopic Characterization, and Theoretical Prediction of the Structure and Electronic Spectrum of Eu(btfa)(3).bipy and an Assessment of the Effect of Fluorine as a beta-Diketone Substituent on the Ligand-Metal Energy Transfer Process.

    PubMed

    Batista, Hélcio J.; de Andrade, Antônio V. M.; Longo, Ricardo L.; Simas, Alfredo M.; de Sá, Gilberto F.; Ito, Nao K.; Thompson, Larry C.

    1998-07-13

    The 2,2'-dipyridyl adducts of two europium beta-diketonate complexes, Eu(btfa)(3).bipy [btfa = 4,4,4-trifluoro-1-phenyl-2,4-butanedione, bipy = 2,2'-dipyridyl] and Eu(bzac)(3).bipy [bzac = 1-phenyl-2,4-butanedione], have been prepared. The crystal structure of the former with chemical formula EuC(40)H(26)O(6)N(2)F(9) has been solved by single-crystal X-ray diffraction methods. The complex crystallizes in the monoclinic space group P2(1)/n with a = 11.122(5) Å, b = 22.860(8) Å, c = 15.870(6) Å, beta = 102.62(3)(o), V = 3937(5) Å(3), and Z = 4. A single, eight-coordinate environment, which approximates a square antiprism, is found for the europium(III). The UV absorption spectra of both complexes were obtained from ethanol solutions and, in the case of Eu(btfa)(3).bipy, from a thin film. In both cases the absorption spectra are reasonably well predicted by the INDO/S-CI method using, for Eu(btfa)(3).bipy, both the X-ray data and that obtained through the SMLC/AM1 method as input geometry and, for Eu(bzac)(3).bipy, that obtained through the SMLC/AM1 method. There is a blue shift of the calculated spectra relative to the solution spectra and a slightly larger blue shift compared to the spectrum of the thin film. Both complexes are luminescent under near-UV excitation, and the spectra are in accord with the existence of a single emitting site in each. The increased quantum yield in the fluorinated complex is correlated with a decrease in the bipy-europium(III) distance, a closer match of the lowest ligand-centered triplet state (that level which is primarily responsible for the energy transfer from the ligands to the europium(III)), and the lower vibrational energy of the C-F bonds relative to the C-H bonds. In the fluorinated complex the calculations show that the lowest triplet level is primarily localized on the 2,2'-dipyridyl whereas in the nonfluorinated complex this is the second lowest triplet level.

  13. 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.

  14. Optical properties of the Eu(III)-La(III)-complex-doped polyolefine film and rod samples

    NASA Astrophysics Data System (ADS)

    Pogreb, Roman; Popov, Oleg; Lirtsman, Vlad; Pyshkin, Oleg; Kazachkov, Alexander; Musin, Albina; Finkelshtein, Binyamin; Shmukler, Yuri; Davidov, Dan; Bormashenko, Edward

    2005-04-01

    The work is devoted to luminescent properties of trivalent lanthanide complexes dispersed in thermoplastic host matrices. Polyethylene-based film and polypropylene-based rod both doped with these complexes were manufactured using an extrusion technique. Two kinds of dopants were used: Eu(III)-thenoyltrifluoroacetone-1,10-phenanthroline complex (Eu(III)) and Eu(III)-La(III)-1,10-phenanthroline complex (Eu(III)-La(III)). Comparison was made between these samples regarding absorption, excitation, emission and a lifetime of luminescence. Dependence of emission intensity on the excitation energy was determined. Emission spectra of the films were studied at room and helium temperatures. Optical properties of Eu(III) samples are different from Eu(III)-La(III) samples. Significant difference in spectra of these two types of samples may be attributed to the La(III) action.

  15. Structure and luminescence of SrY{sub 2}O{sub 4}:Eu

    SciTech Connect

    Park, S.J.; Park, C.H.; Yu, B.Y.; Bae, H.S.; Kim, C.H.; Pyun, C.H.

    1999-10-01

    Powder samples of SrY{sub 2(1{minus}x)}O{sub 4}:Eu{sub 2x} were prepared at 1,000 C by the combustion method. The emission spectrum of SrY{sub 2}O{sub 4}:Eu{sup 3+} showed two kinds of Eu{sup 3+} emissions, which could be assigned to Eu{sup 3+} ions in the Sr site and the Y site. Reducing SrY{sub 2}O{sub 4}:Eu brought a broad band emission around 470 nm, which could be attributed to crystal defects introduced by the reduction. The energy transfer from defects to Eu{sup 3+} ions was observed to be more effective to the Sr site than to the Y site.

  16. Luminescence of Eu and Ce in K3Ca2(SO4)3F fluoride material.

    PubMed

    Poddar, Anuradha; Gedam, S C; Dhoble, S J

    2015-09-01

    A new halophosphor K3Ca2(SO4)3F activated by Eu or Ce and K3Ca2(SO4)3F:Ce,Eu co-doped halosulfate phosphor has been synthesized by the co-precipitation method and characterized for its photoluminescence (PL). The PL emission spectra of the K3Ca2(SO4)3F:Ce phosphor show emission at 334 nm when excited at 278 nm due to 5d → 4f transition of Ce(3+) ions. In the K3Ca2(SO4)3F:Eu lattice, Eu(2+) (440 nm) as well as Eu(3+) (596 nm and 615 nm) emissions have been observed showing (5) D0 →(7) F1 and (5) D0 →(7) F2 transition of the Eu(3+) ion, which is in the blue and red region of the visible spectrum respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems owing to its non-degenerate emitting (5) D0 state. K3Ca2(SO4)3F:Ce,Eu is suitable for Ce(3+) → Eu(2+) → Eu(3+) energy transfer in which Ce(3+) and Eu(2+) play the role of sensitizers and Eu(2+) and Eu(3+) act as the activators. The observations presented in this paper are relevant for lamp phosphors.

  17. Characterization of various Eu2+ sites in Ca2SiO4:Eu2+ and Ba2SiO4:Eu2+ by high-pressure spectroscopy

    NASA Astrophysics Data System (ADS)

    Grinberg, M.; Barzowska, J.; Baran, A.; Kukliński, B.

    2011-12-01

    Photoluminescence of Ba2SiO4 and Ca2SiO4 activated with Eu2+ was investigated at various temperatures (from 10 K to 300 K) and pressures (from ambient to 200 kbar). At ambient pressure and room temperature, under UV excitation both phosphors yielded a green emission band with maxima at 505 nm and 510 nm for Ba2SiO4 and Ca2SiO4, respectively. The energies of these bands depended on pressure; the pressure shifts were -12:55 cm-1/kbar for Ba2SiO4:Eu2+; and -5:59 cm-1/kbar for Ca2SiO4:Eu2+. In the case of Ca2SiO4:Eu2+, we observed additional broadband emission at lower energies with a maximum at 610 nm (orange band). The orange and green emission in Ca2SiO4:Eu2+ had different excitation spectra: the green band could be excited at wavelengths shorter than 470 nm, whereas the orange band — at wavelengths shorter than 520 nm. The pressure caused a red shift of orange emission of 7.83 cm-1/kbar. The emission peaked at 510 nm was attributed to the 4f65d→4f7(8S7=2) transition of Eu2+ in the β — Ca2SiO4:Eu2+ phase, whereas the emission peaked at 610 nm — to the γ — Ca2SiO4:Eu2+ phase. The emission of Ba2SiO4:Eu2+ peaked at 505 nm was attributed to the 4f65d→ 4f7(8S7/2) transition of Eu2+ in the β — Ba2SiO4 phase.

  18. MPC improves reformer control

    SciTech Connect

    Jung, C.S.; Noh, K.K.; Yi, S.; Kim, J.S.; Song, H.K.; Hyun, J.C.

    1995-04-01

    A model predictive control strategy was applied to a synthesis gas reformer of Samsung-BP Chemicals in Korea that produces carbon monoxide and hydrogen from naphtha. A strongly endothermic reaction occurs in a catalytic reformer, and reformer outlet temperature is considered to have the most significant effect on product composition. The newly developed reformer is known to be a cost-effective process operating at high reaction temperatures and low steam-to-carbon ratio, but its drawback is temperature control difficulty due to the use of offgas as a part of the fuel. Without smooth control of the reformer outlet temperature, stable operation of the downstream separation units cannot be expected. Therefore, it is a great challenge to apply a model predictive control technique for tight control of reformer outlet temperature. The paper describes model predictive control, the process advanced control project, computer system architecture, analysis of operating condition, control structure, sampling rate, and disturbance estimation.

  19. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Naphtha reforming process

    SciTech Connect

    Gibson, K.R.; Houston, R.J.; Hughes, T.R.; Jacobson, R.L.

    1984-07-17

    In a process for reforming light naphtha with a bimetallic or multimetallic reforming catalyst, such as a platinum-rhenium-halogen catalyst, at conventional reforming conditions, wherein the catalyst is used for an extended continuous on-stream period, the aromatics selectivity of the catalyst is rapidly increased by contacting the naphtha and hydrogen with the catalyst at increased severity operating conditions, such as a reduced pressure less than 90% of the normal reforming pressure, during an initial portion of the on-stream period.

  1. 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.

  2. Eu(3+) doped down shifting TiO2 layer for efficient dye-sensitized solar cells.

    PubMed

    Kumar, Vinod; Swami, Sanjay Kumar; Kumar, Anuj; Ntwaeaborwa, O M; Dutta, Viresh; Swart, H C

    2016-12-15

    Europium doped TiO2 (TiO2:Eu(3+)) down-shifting (DS) nanophosphors (NPrs) were synthesized by the solution-combustion method with different concentrations of Eu(3+). The X-ray diffraction results confirmed the formation of a polycrystalline tetragonal structure of the TiO2. The emission of colour of the TiO2:Eu(3+) DS NPr was tuned by varying the doping concentration of Eu(3+). The photoluminescence results confirmed that the TiO2:Eu(3+) DS NPrs converted the UV light into visible light by energy down-conversion process, i.e. down-shifting of high energy UV photons to low energy visible photons. These TiO2:Eu(3+) DS NPrs were used to enhance the efficiency of the Dye sensitized solar cell from 8.32% to 8.80%.

  3. 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.

  4. Blue emission of Eu2+-doped translucent alumina

    DOE PAGES

    Yang, Yan; Zhang, Lihua; Kisslinger, Kim; ...

    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

  5. 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.

  6. Theoretical and empirical investigations of KCl:Eu2+ for nearly water-equivalent radiotherapy dosimetry

    PubMed Central

    Zheng, Yuanshui; Han, Zhaohui; Driewer, Joseph P.; Low, Daniel A.; Li, H. Harold

    2010-01-01

    Purpose: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl:Eu2+) a promising dosimetry material. The purpose of this study is to model KCl:Eu2+ point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl:Eu2+ storage phosphor films (SPFs). Methods: KCl:Eu2+ point dosimeters were irradiated using a 6 MV beam at four depths (5–20 cm) for each of five square field sizes (5×5–25×25 cm2). The dose measured by KCl:Eu2+ was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for KCl:Eu2+ films with thicknesses ranging from 1 μm to 1 mm. The work function of the prototype KCl:Eu2+ material was determined by comparing the sensitivity of a 150 μm thick KCl:Eu2+ film to a commercial BaFBr0.85I0.15:Eu2+-based SPF with a known work function. The work function was then used to estimate the sensitivity of a 1 μm thick KCl:Eu2+ film. Results: The simulated dose responses of prototype KCl:Eu2+ point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the 6 MV beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin KCl:Eu2+ film with thickness of the order of 1 μm would have nearly water-equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin KCl:Eu2+ film could provide excellent signal in a 1 cGy dose-to-water irradiation. Conclusions: In conclusion, the authors demonstrate that KCl:Eu2+-based dosimeters can be accurately modeled by a MC method and that 2D KCl:Eu2+ films of the order of 1 μm thick would have

  7. 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.

  8. Synthesis and determination of the structural and optical characteristics of cBN micropowder with Eu{sup 3+} ions

    SciTech Connect

    Leonchik, S. V. Karotki, A. V.

    2013-10-15

    Cubic boron-nitride micropowder with Eu{sup 3+} ions (cBN:Eu) is synthesized under conditions of high pressures and temperatures. The structural, morphological, chemical, and optical characteristics of the cBN:Eu micropowder are studied using X-ray diffraction, energy-dispersive X-ray spectral microanalysis, photoluminescence, and optical transmission methods. It is found that the cBN:Eu lattice parameter is {approx}3.615 A. The intense red luminescence of the cBN:Eu micropowder (red glow), measured in the visible region of the spectrum in the range from 550 to 750 nm, is attributed to intracenter 4f-electron transitions of the Eu{sup 3+} ions. The possible nature of the cBN:Eu micropowder luminescence is discussed.

  9. 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.

  10. 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.

  11. 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.

  12. First-principles calculation on electronic structure and optical property of BaSi2O2N2:Eu2+ phosphor

    NASA Astrophysics Data System (ADS)

    Tong, Zhi-Fang; Wei, Zhan-Long; Xiao, Cheng

    2017-04-01

    The crystal structure, electronic structure and optical properties of BaSi2O2N2:Eu2+ with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba1-xSi2O2N2:Eux become smaller and Eu-N bond length shortens as Eu concentration increases. The band structure of Ba1-xSi2O2N2:Eux exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eu concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba1-xSi2O2N2:Eux. Under the coupling effect between Eu and Ba, Ba in BaSi2O2N2 exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu2+ doping range.

  13. Reforming with polymetallic catalysts

    SciTech Connect

    Baird, W.C. Jr.

    1988-11-29

    This patent describes a process for catalytically reforming, with hydrogen, a hydrocarbon naphtha feed at reforming conditions, the improvement comprising contacting the naphtha feed, and hydrogen, with a halogenated, supported platinum-rhenium catalyst promoted with iridium agglomerated to exhibit a crystallinity greater than 50 percent, as measured by X-ray.

  14. Overcoming Obstacles To Reform.

    ERIC Educational Resources Information Center

    Tierney, William G.

    2001-01-01

    Discusses five core reasons why reform efforts in institutions of higher education so often fail. Roadblocks to reform are identified as: 1) lack of agreement on problems to be solved; 2) unclear time frames and structures; 3) lack of evaluative criteria; 4) failure to articulate changes to the rest of the campus; 5) cultural exhaustion and system…

  15. School Reform. IDRA Focus.

    ERIC Educational Resources Information Center

    IDRA Newsletter, 1998

    1998-01-01

    This theme issue addresses school reform, focusing on accountability, attrition, public-supported private education, equitable education, and schoolwide reform. "School-Student Performance and Accountability" (Jose A. Cardenas) discusses what constitutes good performance in school; the shifting emphasis among the input, output, and…

  16. Educational Reform in Turkey

    ERIC Educational Resources Information Center

    Aksit, Necmi

    2007-01-01

    There are a number of reform initiatives underway in Turkey but some of these, which are concerned with curricular and structural changes, have encountered serious difficulties. This paper begins with a brief summary of school effectiveness and school improvement research guiding many educational reforms. It then gives some information about…

  17. Prison Reform and Indians

    ERIC Educational Resources Information Center

    Keller, Charles

    1976-01-01

    Briefly describing the history of prison reform and the American Indian, this article argues that the "professed" humanitarian philosophy of the reformers would not have been extended to "peoples languishing in prison or sequestered on reservations had it not been expedient for the business interests of the larger society". (JC)

  18. Reform Disconnection in China

    ERIC Educational Resources Information Center

    Walker, Allan; Qian, Haiyan

    2012-01-01

    This article examines many of the frustrations associated with implementing education reforms in mainland Chinese schools. Our basic argument is that when taken individually, many of the recent reforms are beneficial, but when parceled together and thrust hastily at schools, they are unwieldy and disconnected. We suggest that the inability of the…

  19. Thinking about Tax Reform.

    ERIC Educational Resources Information Center

    Boskin, Michael J.

    1985-01-01

    Providing pre-college teachers with an analysis of tax reform is the primary goal of this publication. The present tax system is both inefficient and inequitable. Three goals of tax reform proposals are detailed: (1) fairness--the dimensions of horizontal equity, or equal treatment of equals however defined, and vertical equity, reflecting the…

  20. 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…

  1. Thinking about Tax Reform.

    ERIC Educational Resources Information Center

    Boskin, Michael J.

    1985-01-01

    Providing pre-college teachers with an analysis of tax reform is the primary goal of this publication. The present tax system is both inefficient and inequitable. Three goals of tax reform proposals are detailed: (1) fairness--the dimensions of horizontal equity, or equal treatment of equals however defined, and vertical equity, reflecting the…

  2. 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…

  3. Understanding the photoluminescence characteristics of Eu{sup 3+}-doped double-perovskite by electronic structure calculation

    SciTech Connect

    Ghosh, Binita

    2016-05-23

    Europium-doped luminescent barium samarium tantalum oxide Ba{sub 2}SmTaO{sub 6} (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.

  4. Catalytic reforming process

    SciTech Connect

    Oyekau, S.O.; Swan, G.A.

    1984-03-13

    A process wherein, in a series of reforming zones, or reactors, each of which contains a bed, or beds of catalyst, the catalyst in the leading reforming zones is constituted of supported platinum and a relatively low concentration of rhenium, and the catalyst in the last reforming zone, or reactor of the series, is constituted of platinum and a relatively high concentration of rhenium. The amount of rhenium relative to the platinum in the last reforming zone, or reactor is present in an atomic or weight ratio of rhenium:platinum of at least about 1.5:1; preferably at least about 2:1, and more preferably ranges from about 2:1 to about 3:1. The beds of catalyst are contacted with a hydrocarbon or naphtha feed and hydrogen at reforming conditions to produce a hydrocarbon, or naphtha product of improved octane, and the product is withdrawn.

  5. Health reform through tax reform: a primer.

    PubMed

    Furman, Jason

    2008-01-01

    Tax incentives for employer-sponsored insurance and other medical spending cost about $200 billion annually and have pervasive effects on coverage and costs. This paper surveys a range of proposals to reform health care, either by adding new tax incentives or by limiting or replacing the existing tax incentives. Replacing the current tax preference for insurance with an income-related, refundable tax credit has the potential to expand coverage and reduce inefficient spending at no net federal cost. But such an approach by itself would entail substantial risks, so complementary reforms to the insurance market are essential to ensure success.

  6. Reforming Science: Methodological and Cultural Reforms

    PubMed Central

    Casadevall, Arturo; Fang, Ferric C.

    2012-01-01

    Contemporary science has brought about technological advances and an unprecedented understanding of the natural world. However, there are signs of dysfunction in the scientific community as well as threats from diverse antiscience and political forces. Incentives in the current system place scientists under tremendous stress, discourage cooperation, encourage poor scientific practices, and deter new talent from entering the field. It is time for a discussion of how the scientific enterprise can be reformed to become more effective and robust. Serious reform will require more consistent methodological rigor and a transformation of the current hypercompetitive scientific culture. PMID:22184414

  7. Effect of silver ions and clusters on the luminescence properties of Eu-doped borate glasses

    SciTech Connect

    Jiao, Qing; Wang, Xi; Qiu, Jianbei; Zhou, Dacheng

    2015-12-15

    Highlights: • Ag{sup +} and Ag clusters are investigated in the borate glasses via ion exchange method. • The aggregation of silver ions to the clusters was controlled by the ion exchange concentration. • Eu{sup 3+}/Eu{sup 2+} ions emission was enhanced with the sensitization of the silver species. • Energy transfer process from Ag ions and Ag clusters to Eu ions is identified by the lifetime measurements. - Abstract: Silver ions and clusters were applied to Eu{sup 3+}-doped borate glasses via the Ag{sup +}–Na{sup +} ion exchange method. Eu{sup 3+}/Eu{sup 2+} ion luminescence enhancement was achieved after silver ion exchange. Absorption spectra showed no band at 420 nm, which indicates that silver nanoparticles can be excluded as a silver state in the glass. Silver ion aggregation into clusters during the ion exchange process may be inferred. The effect of silver ions and clusters on rare earth emissions was investigated using spectral information and lifetime measurements. Significant luminescence enhancements were observed from the energy transfer of Ag{sup +} ions and clusters to Eu{sup 3+}/Eu{sup 2+} ions, companied with the silver ions aggregated into the clusters state. The results of this research may extend the current understanding of interactions between rare-earth ions and Ag species.

  8. Comparing the luminescence processes of YVO4:Eu and core-shell YVO4@YF3 nanocrystals with bulk-YVO4:Eu

    NASA Astrophysics Data System (ADS)

    Shirmane, L.; Feldmann, C.; Pankratov, V.

    2017-01-01

    Comparative analysis of bulk, non-coated and core-shelled nanocrystalline YVO4:Eu was performed by means of time-resolved luminescence and VUV excitation luminescence spectroscopy techniques. Nanocrystalline YVO4:Eu samples - both as-prepared and YF3 core-shelled - have been synthesized by means of a microwave-assisted synthesis in ionic liquids, which allows to obtain 10-12 nm nanoparticles with high crystallinity. The results show noticeable differences between bulk and nanocrystalline YVO4:Eu in photoluminescence experimental data, which explains by influence of the nanocrystal surface. A YF3 core-shell layer around YVO4:Eu nanoparticles partially recovers the intensity of the Eu3+ emission. It is demonstrated that the Eu3+ luminescence recovery is achieved at the expense of the suppression of the intrinsic emission but not due to the passivation of surface loss centers in core-shelled nanocrystals. It is also shown that surface loss processes are the reason of the degradation of energy transfer efficiency from the host lattice to Eu3+ under high-energy excitations in vacuum ultraviolet spectral range.

  9. Efficient near-infrared emission in Eu3+-Yb3+-Y3+ tri-doped cubic ZrO2 via down-conversion for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Liao, Jinsheng; Zhou, Dan; Liu, Shaohua; Wen, He-Rui; Qiu, Xin; Chen, Jinglin

    2014-03-01

    Eu3+-Yb3+-Y3+ tri-doped cubic ZrO2 (abbreviated as YSZ:Eu,Yb) phosphors with different doping concentrations of Yb3+ can be synthesized via the Pechini sol-gel method. Efficient near-infrared (NIR) emission in YSZ:Eu,Yb phosphors was demonstrated. The dependence of the intensities of visible and NIR emissions, decay lifetimes and energy-transfer efficiencies on the Yb3+ doping concentration was investigated in detail. It is found that Eu3+, acting as a sensitizer, can efficiently transfer its energy to Yb3+ activator ions in YSZ:Eu,Yb phosphors.

  10. Energy transfer from pyridine molecules towards europium cations contained in sub 5-nm Eu2O3 nanoparticles: Can a particle be an efficient multiple donor-acceptor system?

    NASA Astrophysics Data System (ADS)

    Truillet, C.; Lux, F.; Brichart, T.; Lu, G. W.; Gong, Q. H.; Perriat, P.; Martini, M.; Tillement, O.

    2013-09-01

    Sensitized Eu2O3 nanoparticles coated by polysiloxane have been prepared using a polyol method. Further grafting of pyridine molecules on particles surface enhances 400-times the emission of the Eu3+ cations. The sensitizing effect of the pyridine molecules that transfer a part of their excitation towards Eu3+ has been studied by systematic excitation and emission measurements. All of the de-excitation pathway rates involved in the emission processes of these nanoparticles were determined. In particular, the transfer efficiency which was found independent of the number of sensitizers per particle is equal to 0.13 ± 0.01, a value quite satisfying taking into account that the donors and the acceptors are separated by a polysiloxane spacer of 0.4 nm. Furthermore this multiple donor-acceptor system has been modeled in order to deduce the average transfer efficiency as a function of the single donor-acceptor transfer rate. The theoretical modeling is in complete coherence with the experiments performed on a series of samples varying the thickness of the polysiloxane shell, i.e., the spacing distance between the donors and the acceptors. All these results illustrate the interest of using such structures in applications requiring ultrasensitive detection.

  11. Preparation and fluorescence property of red-emitting Eu{sup 3+}-activated amorphous calcium silicate phosphor

    SciTech Connect

    Kojima, Yoshiyuki; Kamei, Shinnosuke; Nishimiya, Nobuyuki

    2010-02-15

    This paper describes the energy efficient synthesis of a red-emitting Eu{sup 3+}-activated amorphous calcium silicate phosphor produced by heating a Eu{sup 3+}-activated calcium silicate hydrate phosphor. Concentration quenching of the Eu{sup 3+}-activated calcium silicate hydrate phosphor was not observed and the emission intensity did not decrease up to a Eu/(Ca+Eu) atomic ratio of 0.46. Heating of the Eu{sup 3+}-activated calcium silicate hydrate (Eu/(Ca+Eu) atomic ratio = 0.32) phosphor produced an amorphous Eu{sup 3+}-activated calcium silicate phosphor, which had a maximum emission intensity at 870 {sup o}C and emitted in the red under near-ultraviolet irradiation (395 nm). The emission intensity of the Eu{sup 3+}-activated amorphous calcium silicate phosphor was about half that of a commercial BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphor, and shows great potential for application in white light-emitting diodes.

  12. Synthesis and spectral characteristics of Sr 2Y 8(SiO 4) 6O 2: Eu polycrystals

    NASA Astrophysics Data System (ADS)

    Zuev, M. G.; Кarpov, A. M.; Shkvarin, А. S.

    2011-01-01

    Spectral-luminescent characteristics of Sr 2Y 8(SiO 4) 6O 2: Eu powder crystal phosphor with the apatite structure and high-intensity luminescence of Eu 3+ ions have been studied. The charge state of europium in the samples has been characterized by means of X-ray L 3-adsorption spectroscopy. It was established that Eu 3+ forms two types of optical centers. Besides, luminescence of Eu 2+ions was found. Reduction Eu 3+→Eu 2+ was considered, which may be due to VSr∥ vacancy formation in the 4 f crystal lattice position and to negative charge transfer by this vacancy to two EuY3+ ions. Thus, in the silicate lattice there exist inhomogeneously distributed oxygen-deficient centers, which are responsible for nonradiative transfer of excitation energy to Eu 3+ and Eu 2+ ions. To study electron-vibrational interactions in the crystal phosphor samples, their IR and Raman spectra were examined. In the luminescence spectrum of Eu 2+, a series of low-intensity bands caused by interaction of the 4 f65 d state of Eu 2+ with silicate lattice vibrations was observed.

  13. Optical properties of Eu(2+) /Eu(3+) mixed valence phosphor Ca2 SiO2 F2 :Eu(2+) /Eu(3).

    PubMed

    Xie, Mubiao; Zhu, Guoxian; Pan, Rongkai; Xie, Wei

    2017-04-19

    The Eu(2+) /Eu(3+) mixed valence phosphor Ca2 SiO2 F2 :Eu(2+) /Eu(3+) was prepared using a solid-state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca(2+) ions were occupied by both Eu(2+) and Eu(3+) ions in Ca2 SiO2 F2 , and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu(2+) band at ~470 nm and narrow 4f → 4f Eu(3+) peaks upon excitation with n-UV light were observed. The ratio between Eu(2+) and Eu(3+) emissions changed regularly, and the relative intensity of the red component from Eu(3+) became systematically stronger with increasing overall Eu content. As a result, the emission color of these phosphors can be tunable from blue to pink under n-UV light excitation. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Accurate Electronic Structures of Eu-Doped SiAlON Green Phosphor with a Semilocal Exchange-Correlation Potential

    NASA Astrophysics Data System (ADS)

    Yoo, Dong Su; Ryu, Jeong Ho; Lee, Sung-Ho; Cho, Hyun; Chung, Yong-Chae

    2011-06-01

    The crystal structure, electronic structure, and photoluminescence properties of EuxSi6-zAlzOzN8-z (x = 0.01754, z = 0.25) green phosphor were calculated by modified version of the exchange potential proposed by Becke and Johnson [J. Chem. Phys. 124 (2006) 221101]. An interstitially doped Eu atom was found in the atomic channel parallel to the [0001] axis. The additional states originated from the hybridization of Eu 4f and Eu 5d with Si 3p and N 2p. The luminescence properties were analyzed using a quantitative calculation of the energy gap and the wavelength. The calculated emission peak wavelength of Eu from the energy gap between Eu 5d and Eu 4f was 552 nm. Conventional local or semi local density functionals always underestimate the band gap for wide gap semiconductor. In contrast, the calculated results using the semi local potential well agreed with experiment.

  15. Nano-environment effects on the luminescence properties of Eu3+-doped nanocrystalline SnO2 thin films

    NASA Astrophysics Data System (ADS)

    Bazargan, Samad; Leung, K. T.

    2012-11-01

    Nanocrystalline tin (IV) oxide thin films doped with Eu3+ ions are synthesized using a simple spin-coating method followed by postannealing in an O2 flow at 700 °C. Transmission electron microscopy and x-ray photoelectron spectroscopy studies illustrate the incorporation of Eu3+ ions in the films with a high atomic percentage of 2.7%-7.7%, which is found to be linearly dependent on the initial concentration of Eu3+ in the precursor solution. Glancing incidence x-ray diffraction results show that the crystalline grain sizes decrease with increasing the Eu3+ concentration and decreasing the postannealing temperature with the emergence of the Eu2Sn2O7 phase at high Eu3+ concentrations (≥5.3 at.%). Luminescence spectra of these doped samples show the characteristic narrow-band magnetic dipole emission at 593 nm and electric dipole emission at 614 nm of the Eu3+ ions, arising from UV absorption at the SnO2 band-edge followed by energy transfer to the emission centers. Manipulating the crystallite size, composition, and defect density of the samples greatly affects the absorption edge, energy transfer, and therefore the emission spectra. These modifications in the environment of the Eu3+ ions allow the emission to be tuned from pure orange characteristic Eu3+ emission to the broadband emission corresponding to the combination of strong characteristic Eu3+ emission with the intense defect emissions.

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

    DOE PAGES

    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

  17. 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.

  18. 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

  19. Education Reforms: Lessons from History

    ERIC Educational Resources Information Center

    Hunt, Thomas C.

    2005-01-01

    Policy makers in education have long embraced reform. Unfortunately, education reforms have consistently been plagued by the reformers' lack of knowledge and appreciation of the history of education. Accordingly, the latest reform, touted as a panacea, meets with failure, and the search for the magic elixir begins anew. The ahistorical nature of…

  20. Education Reforms: Lessons from History

    ERIC Educational Resources Information Center

    Hunt, Thomas C.

    2005-01-01

    Policy makers in education have long embraced reform. Unfortunately, education reforms have consistently been plagued by the reformers' lack of knowledge and appreciation of the history of education. Accordingly, the latest reform, touted as a panacea, meets with failure, and the search for the magic elixir begins anew. The ahistorical nature of…

  1. 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.

  2. A neutron scintillator based on transparent nanocrystalline CaF{sub 2}:Eu glass ceramic

    SciTech Connect

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

    2016-04-11

    There are no efficient Eu{sup 2+} doped glass neutron scintillators reported due to low doping concentrations of Eu{sup 2+} and the amorphous nature of the glass matrix. In this work, an efficient CaF{sub 2}:Eu glass ceramic neutron scintillator was prepared by forming CaF{sub 2}:Eu nanocrystals in a {sup 6}Li-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 CaF{sub 2} crystals to the Eu{sup 2+} emitting centers. Further light yield improvement is expected if the refractive index of the glass matrix can be matched to the CaF{sub 2} crystal.

  3. 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.

  4. 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.

  5. 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…

  6. 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…

  7. 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…

  8. Consequences of ET and MMCT on Luminescence of Ce(3+)-, Eu(3+)-, and Tb(3+)-doped LiYSiO4.

    PubMed

    Shi, Rui; Liu, Guokui; Liang, Hongbin; Huang, Yan; Tao, Ye; Zhang, Jing

    2016-08-01

    Ce(3+), Eu(3+), and Tb(3+) singly doped, Ce(3+)-Tb(3+), Tb(3+)-Eu(3+), and Ce(3+)-Eu(3+) doubly doped, as well as Ce(3+)-Tb(3+)-Eu(3+) triply doped LiYSiO4 phosphors were prepared by a high-temperature solid-state reaction technique. Rietveld refinement was performed to determine the structure of host compound. The cross-relaxation (CR) of Tb(3+) is quantitatively analyzed with the Inokuti-Hirayama model of energy transfer (ET), and the site occupancy is confirmed by emission spectra of Eu(3+). ET and metal-metal charge transfer (MMCT) are systematically investigated in Ce(3+)-Tb(3+), Tb(3+)-Eu(3+), and Ce(3+)-Eu(3+) doubly doped systems. The combined effects of ET and MMCT on luminescence and emission color of Ce(3+)-Tb(3+)-Eu(3+) triply doped samples are discussed in detail, showing that the photoluminescence emission is tunable in a large color gamut.

  9. 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.

  10. Eu(2)(+) -induced enhancement of defect luminescence of ZnS.

    PubMed

    Xiao-Bo, Zhang; Fu-Xiang, Wei

    2016-12-01

    The Eu(2)(+) -induced enhancement of defect luminescence of ZnS was studied in this work. While photoluminescence (PL) spectra exhibited 460 nm and 520 nm emissions in both ZnS and ZnS:Eu nanophosphors, different excitation characteristics were shown in their photoluminescence excitation (PLE) spectra. In ZnS nanophosphors, there was no excitation signal in the PLE spectra at the excitation wavelength λex  > 337 nm (the bandgap energy 3.68 eV of ZnS); while in ZnS:Eu nanophosphors, two excitation bands appeared that were centered at 365 nm and 410 nm. Compared with ZnS nanophosphors, the 520 nm emission in the PL spectra was relatively enhanced in ZnS:Eu nanophosphors and, furthermore, in ZnS:Eu nanophosphors the 460 nm and 520 nm emissions increased more than 10 times in intensity. The reasons for these differences were analyzed. It is believed that the absorption of Eu(2)(+) intra-ion transition and subsequent energy transfer to sulfur vacancy, led to the relative enhancement of the 520 nm emission in ZnS:Eu nanophosphors. In addition, more importantly, Eu(2)(+) acceptor-bound excitons are formed in ZnS:Eu nanophosphors and their excited levels serve as the intermediate state of electronic relaxation, which decreases non-radiative electronic relaxation and thus increases the intensity of the 460 nm and 520 nm emission dramatically. In summary, the results in this work indicate a new mechanism for the enhancement of defect luminescence of ZnS in Eu(2)(+) -doped ZnS nanophosphors. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Catalytic reforming of naphtha fractions

    SciTech Connect

    Bishop, K.C.; Vorhis, F.H.

    1980-09-16

    Production of motor gasoline and a btx-enriched reformate by fractionating a naphtha feedstock into a mid-boiling btxprecursor fraction, a relatively high-boiling fraction and a relatively low-boiling fraction; catalytically reforming the btxprecursor fraction in a first reforming zone; combining the relatively high-boiling and low-boiling fractions and catalytically reforming the combined fractions in a second reforming zone.

  12. 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.

  13. 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.

  14. Dose enhancing behavior of hydrothermally grown Eu-doped SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Sánchez Zeferino, R.; Pal, U.; Meléndrez, R.; Durán-Muñoz, H. A.; Barboza Flores, M.

    2013-02-01

    Hydrothermally grown SnO2 and SnO2:Eu nanoparticles of 4-11 nm size range were analyzed by photoluminescence (PL) and therrmoluminescence (TL) spectroscopy to study the effect of Eu-doping on their emission behaviors. It has been observed that most of the incorporated Eu3+ ions remain at the interstitial sites of SnO2 lattice. High Eu-contents in the nanoparticles generate lattice deformation, formation of Eu3+/Eu0 clusters at interstitial sites, or segregation to their surfaces. Formation of Eu clusters at interstitial sites enhances electronic defect density in the crystal lattice, reorganizes carrier trapping centers, and modifies their activation energies. Room temperature PL emission and beta-irradiated TL dose response of SnO2 nanoparticles enhance significantly when doped with 0.5 and 1.0 mol. % nominal of Eu3+, respectively, opening up their possibilities of applications in bio-imaging and radiation therapy. Possible mechanisms of enhanced PL and TL responses of the samples have been discussed.

  15. Diffusion and reaction of H2 gas for reducing Eu3+ ions in glasses

    NASA Astrophysics Data System (ADS)

    Nogami, Masayuki; Quang, Vu Xuan; Nonaka, Takamasa; Shimizu, Tadashi; Ohki, Shinobu; Deguchi, Kenzo

    2017-06-01

    We have recently developed new Eu2+-doped Na2O-Al2O3-SiO2 glasses by heating precursors in H2 gas, in which Al3+ ions play an important role in reducing Eu3+ to Eu2+. However, the pathway by which the Eu3+ ions are reduced was not established. To address this question, the structural changes involving Al3+ and Eu3+ ions have been elucidated from Magic-Angle Spinning Nuclear Magnetic Resonance (MAS NMR) in solid state and X-ray absorption fine-structure spectroscopies. In the glasses with Al/Na >1, the Al3+ ions form AlO4 units without incorporating Na+ ions for charge compensation, and the Eu3+ ions are coordinated by a network structure comprising AlO4 and SiO4. When heated in H2 gas, the H2 gas molecules diffuse and react with the Eu3+ ions, reducing them to Eu2+ and forming O-H bonds. The diffusion rate of H2 molecules was analyzed from the formation process of O-H bonds; 3.37×10-12 m2/sec at 700 °C and 39.5 kJ/mol for diffusion coefficient and activation energy, respectively.

  16. Catalytic reforming process

    SciTech Connect

    Baird, W.C. Jr.

    1986-04-01

    This patent describes a process for reforming a paraffinic naphtha feed by introducing the feed, with hydrogen, into a reactor charged with a platinum-containing reforming catalyst, the paraffinic hydrocarbon naphtha feed containing from about 30 to about 100 wt. percent paraffinic hydrocarbons, from about 10 to about 70 wt. percent naphthenes, and from about 5 to about 30 wt. percent aromatics, of which less than about 5 wt. percent are C/sub 8/+ aromatics, and reacting the feed at reforming conditions. The improvement described here consists of: adding to the blend introduced to the reactor sufficient C/sub 8/+ aromatics to increase the C/sub 8/+ aromatics concentration of the feed introduced into the reactor to a level above about 5 wt. percent C/sub 8/+ aromatics; to increase C/sub 5/+ liquid vis-a-vis the paraffinic naphtha feed otherwise similar except that no C/sub 8/+ aromatics are added, similarly reformed.

  17. Catalytic reforming process

    SciTech Connect

    Swan, G.A.

    1982-09-07

    A process, or procedure, is disclosed for the start-up of reforming units, particularly those employing highly active sulfur-sensitive polymetallic, promoted noble metal containing catalysts. On start -up of a reforming unit, a sulfur-containing naphtha feed is fed at reforming conditions over a platinum-catalyst containing lead reactor of a series while bypassing subsequent reactors of the series, the product therefrom is separated into hydrogen-containing gas and C5+ liquid fractions, the hydrogen-containing gas fraction is desulfurized and dried and recycled to the platinum-catalyst containing lead reactor and, after sufficient hydrogen has been generated for operation of a hydrofiner which is used to hydrodesulfurize the naphtha feed for the reformer, product from the platinum-catalyst containing lead reactor is fed to subsequent reactors of the series which contain the more sulfur-sensitive catalysts.

  18. Defense Spending and Reform

    DTIC Science & Technology

    2012-04-02

    Background paper on SIPRI military expenditure data Public Notice, “ Spending and Defending Defense spending has become a highly......Budget; Finance Reform; Military Spending ; Defense Spending ; Budget Cuts 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  19. 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

  20. Multizone naphtha reforming process

    SciTech Connect

    Fleming, B.

    1987-05-05

    This patent describes a catalytic reforming process for conversion of a naphtha hydrocarbon at reforming conditions having at least two segregated catalyst zones. The improvement comprises contacting the hydrocarbon in a first zone with a first catalyst comprising tin and at least one platinum group metal deposited on a solid catalyst support followed by contacting in a second zone with a second catalyst comprising at least one metal selected from the group consisting of platinum group metals deposited on a solid catalyst support.

  1. Formation and spectral probing of transparent oxyfluoride glass-ceramics containing (Eu2+, Eu3+:BaGdF5) nano-crystals

    NASA Astrophysics Data System (ADS)

    Biswas, Kaushik; Balaji, S.; Karmakar, Prantik; Annapurna, K.

    2015-01-01

    In the present study, we report the formation of transparent glass-ceramics containing BaGdF5 nanocrystals under optimum ceramization of SiO2-BaF2-K2O-Sb2O3-GdF3-Eu2O3 based oxyfluoride glass and the energy transfer mechanisms in Eu2+ → Eu3+ and Gd3+ → Eu3+ has been interpreted through luminescence study. The modification of local environment surrounding dopant ion in glass and glass ceramics has been studied using Eu3+ ion as spectral probe. The optimum ceramization temperature was determined from the differential scanning calorimetry (DSC) thermogram which revealed that the glass transition temperature (Tg), the crystallization onset temperature (Tx), and crystallization peak temperature (Tp) are 563 °C, 607 °C and 641 °C, respectively. X-ray diffraction pattern of the glass-ceramics sample displayed the presence of cubic BaGdF5 phase (JCPDS code: 24-0098). Transmission electron microscopy image of the glass-ceramics samples revealed homogeneous distribution of spherical fluoride nanocrystals ranging 5-15 nm in size. The emission transitions from the higher excited sates (5DJ, J = 1, 2, and 3) as well as lowered asymmetry ratio of the 5D0 → 7F2 transition (forced electric dipole transition) to that of the 5D0 → 7F1 transition (magnetic dipole) of Eu3+ in the glass-ceramics when compared to glass sample demonstrated the incorporation of dopant Eu3+ ions into the cubic BaGdF5 nanocrystals with higher local symmetry with enhanced ionic nature. The presence of absorption bands of Eu2+ ions and Gd3+ ions present in the glass matrix or fluoride nanocrystals in the excitation spectra of Eu3+ by monitoring emission at 614 nm indicated energy transfer from (Eu2+ → Eu3+) and (Gd3+ → Eu3+) in both glass and glass-ceramics samples.

  2. Studying CaSO4:Eu as an OSL phosphor

    NASA Astrophysics Data System (ADS)

    Guckan, Veysi; Altunal, Volkan; Nur, Necmettin; Depci, Tolga; Ozdemir, Adnan; Kurt, Kasim; Yu, Yan; Yegingil, Ihami; Yegingil, Zehra

    2017-09-01

    This study was carried out to investigate the properties of the OSL signal from Eu-doped calcium sulfate (CaSO4:Eu) phosphor and study on its thermal behavior as a function of temperature under a series of luminescence experiments. The suitability of its usage as an optically stimulated luminescence (OSL) dosimeter was also checked. CaSO4:Eu was synthesized using the precipitation method and prepared in pellet form. The dopant concentration value was performed as 0.1 mol%. The synthesized CaSO4:Eu was analyzed by X-ray diffraction (XRD) method to confirm the product. To have an idea about the crystallography and microstructure morphology of the material, scanning electron microscope (SEM) analysis were carried out. It was found that the OSL signal is a resultant signal having three components and exhibits thermal quenching above 150 °C. The excitation spectrum of CaSO4:Eu showed different peaks in the region 220-360 nm with the highest one at 269 nm. Thermoluminescence (TL) signals of CaSO4:Eu pellets were obtained and compared with the TL signals obtained after OSL measurements of the same pellets by blue light stimulation. The low temperature peak near 180 °C did not show any significant change in TL after OSL measurement whereas the high temperature peak at 240 °C was bleached with the blue light illumination and might be responsible for the observed OSL signal. The dosimetric properties such as dose response, minimum detectable dose, energy response, reusability, fading properties, thermal stability and effect of reading temperatures on OSL signals were examined. OSL signals of CaSO4:Eu pellets were decreased by approximately 8% at the end of the 24 h and by about 7% at the end of 28 days when compared with the first readout. The thermal stability of the ∼240 °C TL peak and OSL signal using isothermal decay measurements were used to determine the trap parameters. The CaSO4:Eu OSL dosimeter in accordance with the presented study allows a high

  3. 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.

  4. 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.

  5. 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.

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

    SciTech Connect

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

    2016-05-06

    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 Eu{sub 2}O{sub 3} 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 {sup 5}D{sub 0}→{sup 7}F{sub J} transitions of Eu{sup 3+} ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu{sup 3+} ions.

  8. Spectroscopic investigations and phonon side band analysis of Eu3+-doped multicomponent tellurite glasses

    NASA Astrophysics Data System (ADS)

    Sajna, M. S.; Gopi, Subash; Prakashan, V. P.; Sanu, M. S.; Joseph, Cyriac; Biju, P. R.; Unnikrishnan, N. V.

    2017-08-01

    Novel and optically efficient multicomponent tellurite glasses doped with Eu3+ ions were prepared by melt quenching procedure. Absorption, photoluminescence excitation, emission and Raman spectra analyses of the Eu3+-doped glasses have been carried out. Spectroscopic studies were performed with the Judd-Ofelt and phonon side band analyses. The local vibrational mode around Eu3+ ions and the phonon energy of the prepared tellurite glasses was estimated by the phonon side band (PSB) associated with 7F0→5D2 transition of Eu3+ ion. Both the phonon energy (ћω) and the electron-phonon coupling constant (g) were derived from the phonon side band spectrum. Radiative properties such as spontaneous transition probabilities (AT), radiative lifetime (τR) and luminescence branching ratio (βR) ratio were calculated for different excited states. Five pronounced peaks have appeared in the photoluminescence spectra (PL) as a result of the transitions from the metastable 5D0 to the ground states 7FJ (J = 0 to 4) of Eu3+ ions. The red Eu3+ emission at 612 nm corresponding to the 5D0→7F2 transition is of particular importance and its emission intensity is observed to increase significantly with growing Eu3+ ion concentration, suggesting that these multicomponent tellurite glasses are suitable candidates for red laser source applications.

  9. Sensitized luminescence of Sm3+,Eu(3+)-codoped TiO2 nanoparticles.

    PubMed

    Luo, Wenqin; Li, Renfu; Liu, Yongsheng; Chen, Xueyuan

    2010-03-01

    Sm3+,Eu(3+)-codoped TiO2 nanoparticles were prepared by a facile sol-gel-solvothermal method. Sm3+ and Eu3+ were successfully incorporated into a TiO2 lattice and resulted in intense emission lines with resolved crystal-field splitting, in spite of a large mismatch in ionic radius between trivalent lanthanides (Ln3+) and Ti4+. The intense sensitized emissions of Sm3+ and Eu3+ ions by TiO2 host were obtained at room temperature. In this case, Sm3+ also acts as a bridge to transfer energy from TiO2 host to Eu3+ ions, which was not observed in Eu(3+)-doped TiO2 nanoparticles. In comparison with direct excitation of lanthanide ions, the luminescence lifetimes of 4G5/2 of Sm3+ and 5D0 of Eu3+ were observed to be significantly prolonged upon excitation above TiO2 band-gap. A sensitization mechanism to illustrate the energy transfer from TiO2 to Sm3+ and Eu3+ was proposed based on the optical behaviors of the codoped nanoparticles.

  10. Governance in EU illicit drugs policy.

    PubMed

    Edwards, Carel; Galla, Maurice

    2014-09-01

    This commentary represents the authors' views on EU governance in illicit drug policy, a field in which they were active for more than 10 years between them. EU drug policy has a narrow legal basis in the European Treaties and is mostly non-binding. The main policy instruments are 8-year EU Drug Strategies, underpinned by 4-year Action Plans which set out specific objectives at national, EU or international level. The approach that guides EU drug policy is known as the 'balanced approach'. It is remarkably restrained and reflects the reality that very few Member States have either the socio-political culture or the resources to consistently apply the punitive sanctions foreseen by the UN conventions. An important feature of EU governance in the field of drugs is the proactive support that is provided to non-governmental organisations both within the EU as well as in accession, associated or third countries. At a global level, the EU is a major financial aid donor also in this field. This position is not however reflected in corresponding political clout for the EU within the UN system. EU governance on drugs has made it possible for many of its Member States to accommodate the problem rather than to "solve" what by all the evidence from the last 100 years may well be insoluble, at least by means of criminalisation and prohibition. The big question is where EU drug policy is headed in the next few years. The EU has been promoting measures and practices that target real problems. It has done so without indulging too much in unhelpful rhetoric. However, like all successful formulae this one also has a sell-by date. EU governance in the field of drugs cannot afford to stand still. It needs to find a second wind.

  11. Effect of the PVA (polyvinyl alcohol) concentration on the optical properties of Eu-doped YAG phosphors

    NASA Astrophysics Data System (ADS)

    Hora, Daniela A.; Andrade, Adriano B.; Ferreira, Nilson S.; Teixeira, Verônica C.; dos S. Rezende, Marcos V.

    2016-10-01

    The influence of the polyvinyl alcohol (PVA) concentration on the synthesis and structural, morphological and optical properties of Y3Al5O13: Eu (Eu-doped YAG) was systematically investigated in this work. The final concentration of PVA in the preparation step influenced the crystallite size and also the degree of particle agglomeration in Eu-doped YAG phosphors. X-ray excited optical luminescence (XEOL) emission spectra results indicated typical Eu3+ emission lines and an abnormally intense 5D0 → 7F4. The intensity parameters Ω2 and Ω4 were calculated and indicated the PVA concentration affects the ratio Ω2:Ω4. X-ray absorption spectroscopy (XAS) results showed Eu valence did not change and the symmetry around the Eu3+ is influenced by the PVA concentration. XEOL-XAS showed the luminescence increases as a function of energy.

  12. Partnerships for disaster risk insurance in the EU

    NASA Astrophysics Data System (ADS)

    Mysiak, Jaroslav; Dionisio Pérez-Blanco, C.

    2016-11-01

    With increasing costs inflicted by natural hazard perils, and amidst state budget cuts, concerns are mounting about the capacity of governments to design sustainable, equitable and affordable risk management schemes. The participation of the private sector along with the public one through public-private partnerships (PPPs) has gained importance as a means of providing catastrophic natural hazard insurance to address these seemingly conflicting objectives. In 2013 the European Commission launched a wide-ranging consultation about what EU action could be appropriate to improve the performance of insurance markets. Simultaneously, the EU legislator instigated major reforms in the legislation and regulations that pertain to how PPPs are designed or operate. This paper has a dual objective: first, we review and summarize the manifold legal background that influences the provision of insurance against natural catastrophes. Second, we examine how PPPs designed for sharing and transferring risk operate within the European regulatory constraints, illustrated using the example of the UK Flood Reinsurance Scheme (Flood RE) between the state and the Association of British Insurers.

  13. Study of rotational bands and electromagnetic properties of odd mass 153-159Eu

    NASA Astrophysics Data System (ADS)

    Pandit, Rakesh K.; Slathia, Barun; Devi, Rani; Khosa, S. K.

    Some positive and negative parity energy bands of odd-A isotopes of Europium 153-159Eu have been studied within the Projected Shell Model (PSM) framework. Calculated excitation energy spectra, transition energies, E2 and M1 transition probabilities, quadrupole and magnetic moments are compared with experimental data wherever available. Reasonably good agreement is obtained with the observed data.

  14. Polymer thin films containing Eu(III) complex as lanthanide lasing medium

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasuchika; Wada, Yuji; Yanagida, Shozo; Kawai, Hideki; Yasuda, Naoki; Nagamura, Toshihiko

    2003-10-01

    Direct evidence of lanthanide(III) lasing using Eu(III) complex in polymer thin films (threshold level <0.05 mJ) is reported. The thin film consists of polystyrene containing Eu(III) complexes based on two criteria: (1) Higher emission quantum yield of Eu(III) complexes, which increases the rs (energy density), and (2) faster radiation rate at large B (Einstein coefficient). The microcavity was constructed by coating a glass substrate with a film having a high refractive index. The film thickness was found to be 1.71 mm. The threshold level for laser transmission was found to be <0.05 mJ.

  15. 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…

  16. 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…

  17. Beyond "health care reform".

    PubMed

    Heyssel, R M

    1993-03-01

    The author discusses the need to make corrections in the U.S. health care system, describes the simplistic and money-oriented definition that many persons have of "health care reform," and discusses the issues he thinks will and will not be dealt with in the coming reforms of the health care system. He maintains that true reform would deal with matters such as restraining expansion of the health care industry, setting reasonable fees, and confronting the harmful social and environmental conditions that result in high "medical" care costs and poor health statistics. The medical profession--including academic medical centers--has a large role to play in true health care reform, which will involve facing the major barriers (which he outlines) that are now impeding important reforms (e.g., increasing the number of generalist physicians; finding better ways to pay for medical students' and residents' education). The profession cannot make progress in true reform without developing a vision of what the U.S. health care system should be and becoming active in moving toward that vision, acting in the interests of both the individual patient and the community as a whole. The author outlines some of the barriers to finding that vision (such as the influence of third-party payers on the doctor-patient relationship and the fragmentation of medicine and medical education by specialties and subspecialties) and proposes the characteristics and values of the kind of medical education and community involvement of academic medical centers that can help create the needed vision, regain the trust of the public, and thereby reform health care in the interests of both the community and the profession.

  18. 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

  19. 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) .

  20. Governing energy while neglecting health - The case of Poland.

    PubMed

    Vasev, Nikolay

    2017-09-21

    The present article discusses Poland's continued reliance on coal power and the consequent impacts on public health. Concrete aspects of the energy infrastructure and political priorities are shown to compromise as compromising public governance and leading to deteriorated health standards among the general population. To make this case, this study juxtaposes the most recent developments in the Polish energy sector with current measures in EU energy policy and reforms in other EU Member States. Special attention is paid to developments in Poland following the political shift in October 2015, when a new government came to power. The ruling conservative party's direct involvement in the management of the mining and utility companies and its strong political ties to miners' unions are particularly discussed. Theoretically, the article relies on the TAPIC framework for governance. The framework rests on five integral principles of good governance: Transparency, Accountability, Participation, Integrity and Capacity; TAPIC allows scholars to study the impact of governance on public health in any policy area. Methodologically, this study relies on secondary sources, including academic publications, national and international reports, and statistical data on a range of energy and health factors in Poland and Europe. Copyright © 2017 The Author. Published by Elsevier B.V. All rights reserved.

  1. 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.

  2. Intrinsic radioactivity of KSr2I5:Eu2+

    NASA Astrophysics Data System (ADS)

    Rust, M.; Melcher, C.; Lukosi, E.

    2016-10-01

    A current need in nuclear security is an economical, yet high energy resolution (near 2%), scintillation detector suitable for gamma-ray spectroscopy. For current scintillators on the market, there is an inverse relationship between scintillator energy resolution and cost of production. A new promising scintillator, KSr2I5:Eu2+, under development at the University of Tennessee, has achieved an energy resolution of 2.4% at 662 keV at room temperature, with potential growth rates exceeding several millimeters per hour. However, the internal background due to the 40K content could present a hurdle for effective source detection/identification in nuclear security applications. As a first step in addressing this question, this paper reports on a computational investigation of the intrinsic differential pulse height spectrum (DPHS) generated by 40K within the KSr2I5:Eu2+ scintillator as a function of crystal geometry. It was found that the DPHS remains relatively equal to a constant multiplicative factor of the negatron emission spectrum with a direct increase of the 1.46 MeV photopeak relative height to the negatron spectrum with volume. Further, peak pileup does not readily manifest itself for practical KSr2I5:Eu2+ volumes.

  3. Luminescense properties of new complexes of Eu(III) and Tb(III) with heterotopic ligands

    NASA Astrophysics Data System (ADS)

    Patroniak, Violetta; Hnatejko, Zbigniew; Grochowska, Agnieszka M.; Stefankiewicz, Artur R.

    2006-07-01

    As a result of coordination between ligands L and L' and europium(III) and terbium(III) ions, the new architectures were formed. The formulae of the complexes have been assigned on the basis of the spectroscopic data in solution and microanalyses. The europium complexes show excellent luminescence properties with high quantum yield ( 1b-Eu 3L2) and effective intramolecular energy transfer from the ligand to the Eu(III) ions.

  4. Luminescense properties of new complexes of Eu(III) and Tb(III) with heterotopic ligands.

    PubMed

    Patroniak, Violetta; Hnatejko, Zbigniew; Grochowska, Agnieszka M; Stefankiewicz, Artur R

    2006-07-01

    As a result of coordination between ligands L and L' and europium(III) and terbium(III) ions, the new architectures were formed. The formulae of the complexes have been assigned on the basis of the spectroscopic data in solution and microanalyses. The europium complexes show excellent luminescence properties with high quantum yield (1b-Eu(3)L(2)) and effective intramolecular energy transfer from the ligand to the Eu(III) ions.

  5. Contribution of Eu 4f states to the magnetic anisotropy of EuO

    SciTech Connect

    Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

    2008-09-11

    Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

  6. Catalytic reforming process

    SciTech Connect

    Baird Jr., W. C.; Mauldin, C. H.

    1985-09-17

    A start-up procedure wherein a halogenated rhenium-containing catalyst, to improve its performance in reforming naphtha feeds, is contacted with water, added with the hydrogen and said feed. During the start-up period, preferably on initiation of the start-up period after aromatics production has begun, a naphtha feed, hydrogen and water are passed cocurrently through the several reactors of a reforming unit and reacted over the halogenated rhenium-containing catalyst. Water is generally added with the naphtha and hydrogen, preferably to the initial reactor of the series of reactors of the reforming unit, in concentration ranging from about 100 vppm of hydrogen to about 10,000 vppm of hydrogen, preferably from about 100 vppm to about 5000 vppm of hydrogen.

  7. Catalyst reforming process

    SciTech Connect

    Swan, G.A. III

    1989-05-23

    This patent describes a process for catalytically reforming a gasoline boiling range naphtha, with hydrogen, in a semi-regenerative or semi-cyclic reforming process unit comprised of serially connected reactors, inclusive of a lead reactor and one or more downstream reactors, the last of which is the tail reactor, each of which contains a halogenated reforming catalyst comprised of a halide, a Group VIII noble metal, and an inorganic oxide support, the improvement which comprises continuously injecting into each downstream reactor a mixture of water and halide at a water to halide ratio from about 20:1 to about 60:1 wherein the specific ratio of water to halide for each individual downstream reactor is chosen so as to maintain the level of halide on catalyst in each downstream reactor from about 0.5 to 1.5 wt. % based on the total weight of the catalyst.

  8. Method for reforming hydrocarbons

    SciTech Connect

    Brinkmeyer, F.M.; Ewert, W.M.; Fox, H.M.; Rohr, D.F. Jr.

    1993-08-10

    A method is described for reforming a hydrocarbon feedstock using a steam-active reforming catalyst which includes a metal from Group VIII of the Periodic Table of Elements, said method comprising the steps of: (a) contacting a first fixed bed of said catalyst with a regeneration mixture consisting essentially of steam and a source of free oxygen in order to remove deactivating material from said catalyst in said first bed by combustion and produce a regeneration effluent gas stream consisting essentially of steam, inert gas, and free oxygen which is not consumed when said deactivating material is removed from said catalyst in said first bed; (b) removing from said regeneration effluent gas stream said free oxygen which is not consumed when said deactivating material is removed from said catalyst in said first bed; and (c) reforming said hydrocarbon feedstock in a second fixed bed of said catalyst and in the presence of said regeneration effluent gas stream.

  9. Health care reforms.

    PubMed

    Marušič, Dorjan; Prevolnik Rupel, Valentina

    2016-09-01

    In large systems, such as health care, reforms are underway constantly. The article presents a definition of health care reform and factors that influence its success. The factors being discussed range from knowledgeable personnel, the role of involvement of international experts and all stakeholders in the country, the importance of electoral mandate and governmental support, leadership and clear and transparent communication. The goals set need to be clear, and it is helpful to have good data and analytical support in the process. Despite all debates and experiences, it is impossible to clearly define the best approach to tackle health care reform due to a different configuration of governance structure, political will and state of the economy in a country.

  10. Health care reforms

    PubMed Central

    Prevolnik Rupel, Valentina

    2016-01-01

    Abstract In large systems, such as health care, reforms are underway constantly. The article presents a definition of health care reform and factors that influence its success. The factors being discussed range from knowledgeable personnel, the role of involvement of international experts and all stakeholders in the country, the importance of electoral mandate and governmental support, leadership and clear and transparent communication. The goals set need to be clear, and it is helpful to have good data and analytical support in the process. Despite all debates and experiences, it is impossible to clearly define the best approach to tackle health care reform due to a different configuration of governance structure, political will and state of the economy in a country. PMID:27703543

  11. 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.

  12. Education of EU Migrant Children in EU Member States. Research Report

    ERIC Educational Resources Information Center

    Harte, Emma; Herrera, Facundo; Stepanek, Martin

    2016-01-01

    This policy brief looks at the education of EU migrant children in the context of intra-EU mobility. It examines some of the literature and data on the topic in order to identify key differences between EU migrant children and non-migrant children. There are disparities in educational performance between migrants and non-migrants. The brief…

  13. 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.

  14. 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.

  15. Energy.

    ERIC Educational Resources Information Center

    Online-Offline, 1998

    1998-01-01

    This issue focuses on the theme of "Energy," and describes several educational resources (Web sites, CD-ROMs and software, videos, books, activities, and other resources). Sidebars offer features on alternative energy, animal energy, internal combustion engines, and energy from food. Subthemes include harnessing energy, human energy, and…

  16. Energy.

    ERIC Educational Resources Information Center

    Online-Offline, 1998

    1998-01-01

    This issue focuses on the theme of "Energy," and describes several educational resources (Web sites, CD-ROMs and software, videos, books, activities, and other resources). Sidebars offer features on alternative energy, animal energy, internal combustion engines, and energy from food. Subthemes include harnessing energy, human energy, and…

  17. Catalytic reforming process

    SciTech Connect

    Absil, R.P.; Huss, A. Jr.; McHale, W.D.; Partridge, R.D.

    1989-06-13

    This patent describes a catalytic reforming process which comprises contacting a naphtha range feed with a low acidity extrudate comprising an intermediate and/or a large pore acidic zeolite bound with a low acidity refractory oxide under reforming conditions to provide a reaction product of increased aromatic content, the extrudate having been prepared with at least an extrusion-facilitating amount of a low acidity refractory oxide in colloidal form and containing at least one metal species selected from the platinum group metals.

  18. Public Health Law Reform

    PubMed Central

    Gostin, Lawrence O.

    2001-01-01

    Public health law reform is necessary because existing statutes are outdated, contain multiple layers of regulation, and are inconsistent. A model law would define the mission and functions of public health agencies, provide a full range of flexible powers, specify clear criteria and procedures for activities, and provide protections for privacy and against discrimination. The law reform process provides an opportunity for public health agencies to draw attention to their resource needs and achievements and to form ties with constituency groups and enduring relations with the legislative branch of government. Ultimately, the law should become a catalyst, rather than an impediment, to reinvigorating the public health system. PMID:11527757

  19. Public health law reform.

    PubMed

    Gostin, L O

    2001-09-01

    Public health law reform is necessary because existing statutes are outdated, contain multiple layers of regulation, and are inconsistent. A model law would define the mission and functions of public health agen cies, provide a full range of flexible powers, specify clear criteria and procedures for activities, and provide protections for privacy and against discrimination. The law reform process provides an opportunity for public health agencies to draw attention to their resource needs and achievements and to form ties with constituency groups and enduring relations with the legislative branch of government. Ultimately, the law should become a catalyst, rather than an impediment, to reinvigorating the public health system.

  20. Synthesis, characterization and photoluminescence properties of CaSiO3:Eu3+ red phosphor.

    PubMed

    Nagabhushana, H; Nagabhushana, B M; Madesh Kumar, M; Chikkahanumantharayappa; Murthy, K V R; Shivakumara, C; Chakradhar, R P S

    2011-01-01

    CaSiO3:Eu3+ (1-5 mol%) red emitting phosphors have been synthesized by a low-temperature solution combustion method. The phosphors have been well characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical spectroscopy. PXRD patterns reveal monoclinic CaSiO3 phase can be obtained at 900°C. The SEM micrographs show the crystallites with irregular shape, mostly angular. Upon 254 nm excitation, the phosphor show characteristic fluorescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 614 nm corresponding to 5D0→7F2 of Eu3+ ions, which is stronger than the magnetic dipole transition located at 593 nm corresponding to 5D0→7F1 of Eu3+ ions. Different pathways involved in emission process have been studied. Concentration quenching has been observed for Eu3+ concentration>4 mol%. UV-visible absorption shows an intense band at 240 nm in undoped and 270 nm in Eu3+ doped CaSiO3 which is attributed to oxygen to silicon (O-Si) ligand-to-metal charge-transfer (LMCT) band in the SiO3(2-) group. The optical energy band gap is widened with increase of Eu3+ ion dopant. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. 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.

  2. Structure and physical properties of EuTa2O6 tungsten bronze polymorph

    NASA Astrophysics Data System (ADS)

    Kolodiazhnyi, T.; Sakurai, H.; Vasylkiv, O.; Borodianska, H.; Forbes, S.; Mozharivskyj, Y.

    2014-08-01

    A tetragonal tungsten bronze (TTB) polymorph of EuTa2O6 was prepared and analyzed. EuTa2O6 crystallizes in the centrosymmetric Pnam space group (with unit cell: a = 12.3693, b = 12.4254, and c = 7.7228 Å) isomorphous with orthorhombic β-SrTa2O6. In contrast to early reports, we see no evidence of deviation from paramagnetic Curie-Weiss behavior among the Eu2+ 4f7spins in EuTa2O6 down to 2 K. Dielectric constant shows a broad peak at ca. 50 K with dielectric dispersion resembling diffuse phase transition. The relaxation time, however, follows a simple (non-freezing) thermally activated process with an activation energy of 92 meV and an attempt frequency of f0 = 5.79 × 1012 Hz. A thermal conductivity of EuTa2O6 shows a low-temperature (T ≈ 30 K) "plateau" region reminiscent of a glass-like behaviour in Nb-based TTB compounds. This behaviour can be attributed to the loosely bound Eu2+ ions occupying large tricapped trigonal prismatic sites in the EuTa2O6 structure.

  3. Sr3Bi(PO4)3:Eu2+ Luminescence, Concentration Quenching and Crystallographic Sites

    NASA Astrophysics Data System (ADS)

    Gao, Shao-Jie; Li, Ting; Zhang, Zi-Cai; Li, Pan-Lai; Wang, Zhi-Jun; Yang, Zhi-Ping

    2014-07-01

    A blue emitting phosphor Sr3Bi(PO4)3:Eu2+ is synthesized by a high-temperature solid state method, and its luminescent property is investigated. Sr3Bi(PO4)3:Eu2+ can create blue emission under the 332 radiation excitation, and the prominent luminescence in blue (423 nm) due to the 4f 5d1 →4 f7 transition of the Eu2+ ion. The crystallographic sites of the Eu2+ ion in Sr3Bi(PO4)3 are analyzed, and the 420 and 440 nm emission peaks of the Eu2+ ion are assigned to the nine-coordination and eight-coordination, respectively. The emission intensity of Sr3Bi(PO4)3:Eu2+ is influenced by the Eu2+ doping content, and the concentration quenching effect is observed. The quenching mechanism is the dipole-dipole interaction, and the critical distance of energy transfer is calculated by the concentration quenching method to be approximately 1.72 nm.

  4. 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.

  5. Theoretical and empirical investigations of KCl:Eu{sup 2+} for nearly water-equivalent radiotherapy dosimetry

    SciTech Connect

    Zheng Yuanshui; Han Zhaohui; Driewer, Joseph P.; Low, Daniel A.; Li, H. Harold

    2010-01-15

    Purpose: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl:Eu{sup 2+}) a promising dosimetry material. The purpose of this study is to model KCl:Eu{sup 2+} point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl:Eu{sup 2+} storage phosphor films (SPFs). Methods: KCl:Eu{sup 2+} point dosimeters were irradiated using a 6 MV beam at four depths (5-20 cm) for each of five square field sizes (5x5-25x25 cm{sup 2}). The dose measured by KCl:Eu{sup 2+} was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for KCl:Eu{sup 2+} films with thicknesses ranging from 1 {mu}m to 1 mm. The work function of the prototype KCl:Eu{sup 2+} material was determined by comparing the sensitivity of a 150 {mu}m thick KCl:Eu{sup 2+} film to a commercial BaFBr{sub 0.85}I{sub 0.15}:Eu{sup 2+}-based SPF with a known work function. The work function was then used to estimate the sensitivity of a 1 {mu}m thick KCl:Eu{sup 2+} film. Results: The simulated dose responses of prototype KCl:Eu{sup 2+} point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the 6 MV beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin KCl:Eu{sup 2+} film with thickness of the order of 1 {mu}m would have nearly water-equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin KCl:Eu{sup 2+} film could provide excellent signal in a 1 cGy dose-to-water irradiation. Conclusions: In conclusion, the authors demonstrate that KCl:Eu{sup 2+}-based dosimeters can be

  6. 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…

  7. Women, Class, and School Reform.

    ERIC Educational Resources Information Center

    Mickelson, Roslyn Arlin; Wadsworth, Angela L.

    1996-01-01

    Analyzes ordinary women's role in shaping school reform in their community, highlighting interplay of class conflict, regionalism, and gender roles in reform efforts. The women protesting the Odyssey Project framed the debate as a juncture between a national, elitist reform movement and a local grassroots countermovement protecting children,…

  8. 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)

  9. 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)

  10. 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…

  11. Pure and strong red photoluminescence from Na0.5Gd0.5TiO3: Eu ferroelectric thin films under ultraviolet light excitation

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Sun, Lina; Tan, Jun; Li, Xinsheng; Liu, Dongyun; Liang, Duoqiang

    2017-02-01

    A series of novel photoluminescent ferroelectric thin films Na0.5Gd0.5TiO3: xEu (NGT: Eu) with various Eu3+ doping concentrations were prepared at various heat-treated temperature, which have single pseudo-cubic perovskite structure at proper heat-treated temperature from 700 °C to 800 °C according to X-ray diffraction results. There existed narrow and intensive emission bands located at red light region ascribed to 5D0 → 7F2 and 5D0 → 7F1 transitions of Eu3+ by 283 nm excitation. The strong energy absorption of NGT host and efficient energy transfer to Eu3+ should be primarily responsible for the emissions. Gd3+ acts as sensitizer which has an important role on the energy transfer from the host NGT to Eu3+. The luminescence from NGT: 0.25Eu thin films is the strongest for all the NGT: Eu films, and its color coordinate is (0.65, 0.32) close to ideal red light. The quenching concentration in NGT: Eu films reaches as high as 25%. The lifetime of emissive energy level Eu3+: 5D0 in NGT: 0.1Eu and NGT: 0.5Eu thin films is 1.024 ms and 0.931 ms, respectively. Finally, the ferroelectric property of NGT: 0.25Eu thin films was tested and the remanent polarization (2Pr) is 7.10 μC/cm2 lower than that of Na0.5Bi0.5TiO3.

  12. Reddish-orange, neutral and warm white emissions in Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses

    NASA Astrophysics Data System (ADS)

    Rodríguez-Carvajal, David A.; Meza-Rocha, A. N.; Caldiño, U.; Lozada-Morales, R.; Álvarez, E.; Zayas, Ma. E.

    2016-11-01

    Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with Tesbnd Osbnd Te and Gesbnd Osbnd Ge related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370-420 nm) based LEDs. The Eu3+ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy3+ singly doped glass excited at 388 nm. The Dy3+/Eu3+ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy3+ and Eu3+ relative excitation. The Dy3+ excitation bands observed in the Dy3+/Eu3+ glass by monitoring the 611 nm Eu3+ emission, suggest that Dy3+ → Eu3+ energy transfer takes place, despite the fact that the Dy3+ emission decays in the Dy3+ and Dy3+/Eu3+ doped glass, remain without changes. The shortening of Eu3+ decay in presence of Dy3+ was attributed to an Eu3+ → Dy3+ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s-1, respectively.

  13. Synthesis and characterization of Mg2SiO4:Tb3+, Eu3+ phosphors for white light generation

    NASA Astrophysics Data System (ADS)

    Cho, Shinho

    2016-09-01

    The effect of Eu3+ codoping on the structural, morphological, and optical properties of Mg2SiO4:Tb3+ was investigated. The phosphor powders were synthesized by changing the molar concentration of Eu3+ at a fixed Tb3+ content of 5 mol% by using a conventional solid-state reaction. The X-ray diffraction patterns revealed that the crystal structure of all the phosphors, irrespective of the Eu3+ and the Tb3+ contents, showed an orthorhombic structure, and the surface morphology exhibited pebble-like crystalline grains. The emission spectra of Eu3+ and Tb3+-codoped Mg2SiO4 phosphors under an ultraviolet excitation of 252 nm consisted of one intense red band at 619 nm and five weak bands at 448, 488, 598, 658, and 707 nm originating from the transitions of Eu3+, in addition to the several emission bands located at 492, 552, 592, and 628 nm arising from the transitions of Tb3+. As the Eu3+ content was increased, the intensity of the main green emission band at 552 nm decreased markedly and disappeared at 10 mol% Eu3+, when complete energy transfer from Tb3+ to Eu3+ was observed. The results suggest that the emission wavelength and the luminescent intensity of the phosphors can be tuned by modulating the Eu3+ and the Tb3+ contents incorporated into the host matrix.

  14. Concentration quenching of Eu{sup 2+} doped Ca{sub 2}BO{sub 3}Cl

    SciTech Connect

    Seed Ahmed, H.A.A.; Swart, H.C.; Bergman, Peber; Kroon, R.E.

    2016-03-15

    Highlights: • Ca{sub 2}BO{sub 3}Cl doped with Eu{sup 2+} prepared by solid state reaction. • Concentration quenching studied by intensity and lifetime measurements. • Accurate determination of the critical transfer distance. • Interaction mechanism verified to be dipole–dipole interactions. - Abstract: With the aim of determining the concentration quenching mechanism of Eu{sup 2+} doped Ca{sub 2}BO{sub 3}Cl, a series of phosphors with a varied Eu{sup 2+} concentration (Ca{sub 2−x}BO{sub 3}Cl:xEu{sup 2+}) was synthesized by the solid state reaction method. The phase structure was determined by X-ray diffraction. Photoluminescence (PL) measurements showed broad excitation and emission signatures of the allowed f–d transition of Eu{sup 2+} ions. The PL emission intensity was found to be increased by increasing the concentration of Eu{sup 2+} ions up to x = 0.03 and then decreased as a result of the concentration quenching effect. The lifetime of the emission from the Eu{sup 2+} ions was measured and the decrease in the lifetime with increasing Eu{sup 2+} concentration confirmed that non-radiative energy transfer occurred between Eu{sup 2+} ions. From the luminescence data, the value of the critical transfer distance was calculated as 1.5 nm and the corresponding concentration quenching mechanism was verified to be a dipole–dipole interaction.

  15. Eu2+-activated Ba3Ca3(PO4)4 phosphor with doping-concentration dependent luminescence

    NASA Astrophysics Data System (ADS)

    Tang, Huidong; Yang, Rong; Li, Rongzhu

    2017-10-01

    A color tunable phosphor of Eu2+-activated monophosphate Ba3Ca3(PO4)4 was developed via facile solid-state reaction synthesis. The samples were tested by X-ray powder diffraction (XRD) patterns, morphological properties, luminescence and decay lifetime measurements. The structural characteristics were discussed. The excitation bands of the phosphors cover the UV-, near-UV and blue-wavelength bands extending from 300 to 440 nm. The luminescence spectra of the phosphors show a great dependence on the Eu2+-concentration in Ba3Ca3(PO4)4, which can give blue to yellow emission colors. There are two kinds of Eu2+ centers in Ba3Ca3(PO4)4 lattices, which give yellow (EuI) and blue (EuII) luminescence with the maximum wavelength at 565 nm and 450 nm, respectively. The structural occupations and luminescence properties of EuI and EuII centers were discussed. EuI (yellow center) has a dominant contribution to the total luminescence with the increase of the Eu2+-doping level. The luminescence internal quantum efficiency and thermal stability (activation energy) were reported. The reported results could be helpful for the further potential application of the phosphor.

  16. Solid state synthesis and tunable luminescence of Li2SrSiO4:Eu2+/Ce3+ phosphors

    NASA Astrophysics Data System (ADS)

    Wei, Zhen; Wang, Yongli; Zhu, Xiaobo; Guan, Jinyu; Mao, Weixi; Song, Juanjuan

    2016-03-01

    Li2SrSiO4:Eu2+/Ce3+ phosphors have been synthesized by solid state reaction. Eu2+ and/or Ce3+ doped Li2SrSiO4 have the hexagonal crystal structure, indicating the doped Eu2+ and/or Ce3+ ions have no influence on the crystal structure of Li2SrSiO4. Under the excitation at 365 nm, Eu2+ or Ce3+ doped Li2SrSiO4 phosphors give characteristic emission bands of Eu2+ or Ce3+, respectively. For Li2SrSiO4:Eu2+/Ce3+ phosphors with the fixed Ce3+ concentration, two emission bands originating from Eu2+ and Ce3+ can be observed. On the basis of luminescent properties of Li2SrSiO4:Eu2+/Ce3+ phosphors, we can conclude that energy transfer from Ce3+ to Eu2+ occurs in Li2SrSiO4.

  17. Mesoporous Europium-Doped Titania Nanoparticles (Eu-MTNs) for Luminescence-Based Intracellular Bio-Imaging.

    PubMed

    Chen, Kuan-Chou; Dutta, Saikat; Yamauchi, Yusuke; Alshehri, Saad M; Nguyen, Mai Thanh; Yonezawa, Tetsu; Shen, Kun-Hung; Wu, Kevin C W

    2015-12-01

    Monodisperse and mesoporous europium (Eu)-doped titania nanoparticles (denoted as Eu-MTNs) were prepared by a co-synthesis method with the presence of a cationic surfactant (i.e., CTAB). A maximum loading amount of 8 mol% of Eu could be successfully incorporated into the framework of MTNs. The synthesized Eu-MTNs samples were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM), with their luminescent property examined by photoluminescence (PL). Under ultraviolet irradiation, the Eu-MTNs samples exhibit several characteristic luminescence corresponding to 5D0-7F(j) for Eu+3 ions, which can be attributed to the energy transfer from titania nanocrystallite to Eu3+ ions dispersed in amorphous mesoporous titania region. The potential intracellular bio-imaging application of the synthesized Eu-MTN nanoparticles was demonstrated with a breast cancer cell line (i.e., BT-20). High biocompatibility and strong luminescence of the Eu-MTNs show great potential in biomedical applications.

  18. Blue-emitting Eu2+-activated LaOX (X = Cl, Br, and I) materials: crystal field effect.

    PubMed

    Kim, Donghyeon; Park, Sangha; Kim, Sungyun; Kang, Seong-Gu; Park, Jung-Chul

    2014-11-17

    Novel blue-emitting LaOBr:Eu(2+) and LaOI:Eu(2+) phosphors have been successfully synthesized and compared to LaOCl:Eu(2+). The emission spectra of LaOX:Eu(2+) (X = Cl, Br, and I) show that the peak maxima change somewhat to the red-shift region; 425 nm for LaOCl:Eu(2+), 427 nm for LaOBr:Eu(2+), and 431 nm for LaOI:Eu(2+), which is quite opposite to one based on spectrochemical series (I(-) < Br(-) < Cl(-)). From diffuse reflectance spectra, the band gap energies for LaOCl, LaOBr, and LaOI host lattice are estimated as 5.53 eV (44,594 cm(-1)), 5.35 eV (43,142 cm(-1)), and 4.82 eV (38,868 cm(-1)), respectively, using the Kubelka-Munk function. For LaOX host lattices, the band gap energies are gradually decreased going from Cl to I as the order of energy levels of np orbitals is Cl 3p < Br 4p < I 5p. A quantum wave function calculation from crystal field theory (CFT) indicates the same tendency with experimental data in the LaOX:Eu(2+) (X = Cl, Br, and I) phosphor materials. With considerations of the radial wave function shape, crystral structure differences and electronegativities among phosphor materials, the splitting energies of 5d orbitals are calculaed; ΔECl = 14,597 cm(-1), ΔEBr = 14,864 cm(-1), ΔEI = 15,001 cm(-1) for LaOX:Eu(2+) (X = Cl, Br, and I). It is noteworthy that the crystal field strength decreases when the interatomic distance decreases, which is probably dependent on the ionic radius of halide ions in the series of LaOX:Eu(2+) phosphor materials.

  19. The Radiative Strength Function Using the Neutron-Capture Reaction on 151,153Eu

    SciTech Connect

    Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R; Esch, E; Folden, 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

    Radiative strength functions in {sup 152,154}Eu nuclei for {gamma}-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. Properties of resonances in these two nuclei are examined. The measurements are compared to simulation of cascades performed with various models for the radiative strength function. Comparison between experimental data and simulation suggests an existence of the low-energy resonance in these two nuclei.

  20. Variation of the Eu(II) emission wavelength by substitution of fluoride by hydride in fluorite-type compounds EuH(x)F(2-x) (0.20 ≤ x ≤ 0.67).

    PubMed

    Kunkel, Nathalie; Meijerink, Andries; Kohlmann, Holger

    2014-05-19

    Mixed-hydride fluorides EuHxF2-x were prepared by the solid-state reaction of EuF2 and EuH2 under hydrogen gas pressure in an autoclave. Eu(II) luminescence is observed for 0.20 ≤ x ≤ 0.67, while pure EuF2 does not show any emission. The energy of the emission depends strongly on the degree of substitution x. For low hydride contents, yellow emission is observed, whereas higher hydride contents lead to red emission. The red shift is attributed to the nephelauxetic effect of the hydride anion. Remarkably, limited concentration quenching is observed in EuHxF2-x (0.20 ≤ x ≤ 0.67). This observation is explained by suppression of long-range energy migration due to disorder in the local environment of Eu(2+) in the mixed H/F crystals. The strong x dependence of the luminescence maxima proves hydride-fluoride substitution to be a valuable tool to tune the emission wavelength of Eu(II)-containing phosphors.

  1. Catalytic reforming process

    SciTech Connect

    Markley, G.E.

    1984-04-03

    A process wherein, in a series of reforming zones, employing one or a series of reactors, each of which contains a bed, or beds of catalyst, the catalyst in the rearward most reforming zones is constituted of supported platinum and a relatively high concentration of rhenium, and the catalyst in the forward most reforming zone is constituted of platinum, or platinum and a relatively low concentration of a promoter metal, especially rhenium. In the rearward reaction zones, at least 40 percent, and preferably from 40 percent to about 90 percent, based on the total weight of catalyst in the reactor, or reactors of the unit, is constituted of a rhenium promoted platinum catalyst, the weight ratio of rhenium:platinum of which at least about 1.5:1, and preferably 2:1, or greater. The beds of catalyst are contacted at start-of-run temperatures ranging from about 875/sup 0/ F. to about 935/sup 0/ F. with a hydrocarbon or naphtha feed, and hydrogen, at reforming conditions to produce a hydrocarbon, or naphtha product of improved octane, and the product is withdrawn.

  2. Catalytic reforming process

    SciTech Connect

    Winter, W.E.; Markley, G.E.

    1984-04-03

    A process wherein, in a series of reforming zones, employing one or a series of reactors, each of which contains a bed, or beds of catalyst, the catalyst in the rearward most reforming zones is constituted of supported platinum and a relatively high concentration of rhenium, and the catalyst in the forward most reforming zone is constituted of platinum, or platinum and a relatively low concentration of a promoter metal, especially rhenium. In the rearward reaction zones, at least 40 percent, and preferably from 40 percent to about 90 percent, based on the total weight of catalyst in the reactor, or reactors of the unit, is constituted of a rhenium promoted platinum catalyst, the weight ratio of rhenium: plantinum of which at least about 1.5:1, a preferably 2:1, or greater. The beds of catalyst are contacted with a hydrocarbon or naphtha feed, and hydrogen, at reforming conditions to produce a hydrocarbon, or naphtha product of improved octane, and the product is withdrawn.

  3. Educational Reform: Who Benefits?

    ERIC Educational Resources Information Center

    Steffy, Betty E.

    1994-01-01

    Uses Blau and Scott concept of "cui bono" to describe who has benefited from 1990 Kentucky Education Reform Act. In eyes of legislators, everyone would benefit, and the economically depressed state would prosper. As implementation of KERA progresses, it is becoming increasingly clear that mandated changes may be structural and may…

  4. Computers and School Reform.

    ERIC Educational Resources Information Center

    McDaniel, Ernest; And Others

    1993-01-01

    Discusses ways in which computers can be used to help school reform by shifting the emphasis from information transmission to information processing. Highlights include creating learning communities that extend beyond the classroom; educationally oriented computer networks; Professional Development Schools for curriculum development; and new…

  5. 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…

  6. 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…

  7. Educational Reforms in Yugoslavia

    ERIC Educational Resources Information Center

    Kintzer, Frederick C.

    1978-01-01

    Yugoslavia's educational system had to be completely rebuilt after World War II to ensure the nation's full and rapid competition in the postwar world. The reforms are discussed in light of the political, social, and economic structure of Yugoslavia. (Author/LBH)

  8. The buzz on reform.

    PubMed

    Bouchard, E A

    1994-01-01

    Mr. Bouchard bravely travels through the maze of lingo and anagrams spawned by recent attempts at healthcare reform. This comprehensive list of terminology and definitions, which provides considerable detail and analysis, will be invaluable to anyone trying to understand current trends.

  9. Prisons and Sentencing Reform.

    ERIC Educational Resources Information Center

    Galvin, Jim

    1983-01-01

    Reviews current themes in sentencing and prison policy. The eight articles of this special issue discuss selective incapacitation, prison bed allocation models, computer-scored classification systems, race and gender relations, commutation, parole, and a historical review of sentencing reform. (JAC)

  10. Mastering School Reform.

    ERIC Educational Resources Information Center

    Goens, George A.; Clover, Sharon I. R.

    School organizations must become responsive and flexible to address rapidly changing social, economic, and demographic conditions. Reform attempts to date have not worked because they were layered on old structures and perceptions in a fragmented, piecemeal fashion. The fundamental transformation of education that is required demands a paradigm…

  11. 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…

  12. 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…

  13. 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…

  14. The Reformation of Schooling.

    ERIC Educational Resources Information Center

    Rubin, Louis

    The necessity for reforming public education is evidenced in part by the failures of past programs and in part by the requirements of the future. The anti-school mood of the present is forcing a more realistic evaluation of the potentiality education possesses in counteracting the disintegrative forces of family breakdown, individual deprivation,…

  15. Educational Reform in Louisiana.

    ERIC Educational Resources Information Center

    Maxcy, Spencer J.; Maxcy, Doreen O.

    1993-01-01

    Although education has appealed to southern governors as a catapult to historical recognition, future governors should consider Louisiana Governor Buddy Roemer's ill-fated educational reform plan for Louisiana State University's College of Education, particularly its teacher evaluation and internship program. Public education seems a low-priority…

  16. 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…

  17. 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…

  18. 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…

  19. Papers on Educational Reform.

    ERIC Educational Resources Information Center

    Open Court Publishing Co., La Salle, IL.

    The following papers collected in this publication were presented for discussion at the Open Court Editorial Advisory Board Meeting in 1970. "Testing, Grades, Standards" by Jacques Barzun discusses the relationship between these three elements and the process of education and of performance evaluation. In "The Limits of Reform in Education" James…

  20. Educational Reform in Turkey

    ERIC Educational Resources Information Center

    Lindquist, Cynthia

    2017-01-01

    As a country seeking admission to the European Union, this paper explores educational reforms in Turkey that enhance its possible entry into the European Union and changes still needed for it to be an equal partner. An overview of the school system in Turkey is provided including information on teacher training and preparation, special education…

  1. 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…

  2. 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…

  3. Cofluorescence of Eu 3+ in complexes of aromatic carboxylic acids

    NASA Astrophysics Data System (ADS)

    Panigrahi, B. S.; Peter, Susy; Viswanathan, K. S.

    1997-12-01

    The fluorescence of Eu 3+ in certain Eu 3+-aromatic acid complexes were enhanced by over two orders of magnitude, by the addition of La 3+; a process referred to as cofluorescence. Cofluorescence was observed only with certain aromatic acid ligands; trismesic acid, pyromellitic acid and mellitic acid; thereby clearly establishing a correlation between the structure of the ligand and the process of cofluorescence. While cofluorescence has been extensively studied using β-diketones as ligands, our studies demonstrate cofluorescence for the first time in ligands other than β-diketones. Furthermore, the mechanism of cofluorescence in the aromatic acid complexes studied by us appears to be different from that operating in the β-diketones. While intermolecular energy transfer is believed to occur in the β-diketones, formation of polynuclear complexes appears to be responsible for cofluorescence in the aromatic acid ligands.

  4. Support systems for poor readers: empirical data from six EU member states.

    PubMed

    Ise, Elena; Blomert, Leo; Bertrand, Daisy; Faísca, Luís; Puolakanaho, Anne; Saine, Nina L; Surányi, Zsuzsanna; Vaessen, Anniek; Csépe, Valeria; Lyytinen, Heikki; Reis, Alexandra; Ziegler, Johannes C; Schulte-Körne, Gerd

    2011-01-01

    This study surveyed and compared support systems for poor readers in six member states of the European Union (EU). The goal was to identify features of effective support systems. A large-scale questionnaire survey was conducted among mainstream teachers (n = 4,210) and remedial teachers (n = 2,395). Results indicate that the six support systems differed substantially, with effective support systems showing high performance on all variables measured. More specifically, effective support systems were characterized by (a) high levels of both teacher and student support and (b) frequent interactions between teachers and remedial teachers as well as between remedial teachers and diagnosticians. The high prevalence of poor reading ability in the current EU member states demonstrates that educational reforms are critically needed. The results of this study provide concrete starting points for improving support systems for poor readers.

  5. EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet

    DOE PAGES

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

    2016-07-19

    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 temperature T≤TNmore » 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. Additionally, 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

  6. Photoluminescence enhancement in Na3SO4Cl:X (X = Ce3+, Eu3+ or Dy3+) material.

    PubMed

    Shinde, Nita; Dhoble, N S; Gedam, S C; Dhoble, S J

    2015-09-01

    The compound Na3SO4Cl X (X = Ce(3+), Eu(3+) or Dy(3+)) prepared by the wet chemical method was studied for its photoluminescence (PL) and energy transfer characteristics. The PL from Na3 SO4 Cl:Ce(3+) shows strong emission at 322 nm at an excitation of 272 nm. Therefore, an efficient Ce(3+) → Dy(3+), Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer had taken place in this host. The Dy(3+) emission caused by Ce(3+) → Dy(3+) energy transfer under ultraviolet (UV) wavelengths peaked at around 477 nm and 572 nm due to (4) F9/2 → (6) H15/2 and (6) H13/2 transitions with yellow-orange emission in the Na3 SO4 Cl lattice. An intense Dy(3+) emission was observed at 482 and 576 nm caused by the Eu(2+) → Dy(3+) energy transfer process and due to (4) F9/2 → (6) H15/2 and (4) F9/2 → (6) H13/2 transitions respectively. The Eu(3+) blue to red light emission caused by the Eu(2+) → Eu(3+) energy transfer peaked at 593 nm and 617 nm due to (5) D0 → (5) D3 transitions. The presence of trivalent Eu in Na3 SO4 Cl suggested the presence of Eu(3+) in the host compound that occupied two different lattice sites and that peaked at 593 and 617 nm due to (5) D0 → (7) F1 and (5) D0 → (7) F2 transitions respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems due to its non-degenerate emitting (5) D0 state. The present paper discusses the photoluminescence characteristics of Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer. This compound may be useful as a lamp phosphor. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Site spectroscopy of Eu3+ doped- ZnS nanocrystals embedded in sodium carboxymethyl cellulose matrix

    NASA Astrophysics Data System (ADS)

    Ahemen, I.; Meludu, O.; Dejene, F. B.; Viana, B.

    2016-11-01

    The work investigates the incorporation of Eu3+ ion in ZnS crystal through spectroscopic studies. ZnS: Eu3+ nanocrystals was synthesized via the precipitation technique. Elemental composition analysis indicates a non-stoichiometric distribution between Zn and S. X-ray diffraction studies show lattice expansion demonstrating that Eu3+ ions were incorporated in the host lattice. Annealing temperature gave rise to lattice contraction relative to the as-synthesized indicating a partial expulsion of the ion from the crystal due to heat treatment. Eu3+ ions site symmetry probing from optical features show that trivalent europium were situated both at the nanocrystals surface and at the Zn2+ ion site. Weak energy transfer from host to activator ion occurred probably mainly through exchange interaction and the transfer process was defect mediated.

  8. 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.

  9. 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.

  10. Persistent Luminescence in Non-Eu2+-Doped Compounds: A Review

    PubMed Central

    Van den Eeckhout, Koen; Poelman, Dirk; Smet, Philippe F.

    2013-01-01

    During the past few decades, the research on persistent luminescent materials has focused mainly on Eu2+-doped compounds. However, the yearly number of publications on non-Eu2+-based materials has also increased steadily. By now, the number of known persistent phosphors has increased to over 200, of which over 80% are not based on Eu2+, but rather, on intrinsic host defects, transition metals (manganese, chromium, copper, etc.) or trivalent rare earths (cerium, terbium, dysprosium, etc.). In this review, we present an overview of these non-Eu2+-based persistent luminescent materials and their afterglow properties. We also take a closer look at some remaining challenges, such as the excitability with visible light and the possibility of energy transfer between multiple luminescent centers. Finally, we summarize the necessary elements for a complete description of a persistent luminescent material, in order to allow a more objective comparison of these phosphors. PMID:28811409

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Fernández-Perea, Mónica; Vidal-Dasilva, Manuela; Aznárez, José A.; Larruquert, Juan I.; Méndez, José A.; Poletto, Luca; Garoli, Denis; Malvezzi, A. Marco; Giglia, Angelo; Nannarone, Stefano

    2008-12-01

    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 O2,3 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 O2,3 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.

  13. Fluorescence line narrowing spectroscopy of Eu{sup 3+} in zinc-thallium-tellurite glass

    SciTech Connect

    Tuyen, V.P.; Hayakawa, T.; Nogami, M.; Duclere, J.R-.; Thomas, P.

    2010-11-15

    The environment of Eu{sup 3+} in zinc-thallium-tellurite glass of the molar composition 60TeO{sub 2}-30TlO{sub 0.5}-9.9ZnO-0.1Eu{sub 2}O{sub 3} was investigated by laser-induced fluorescence line narrowing (FLN) techniques using Eu{sup 3+} as a local site probe. From the site selective luminescence spectra of Eu{sup 3+} at 7 K, the energies of the Stark components of the {sup 7}F{sub 1} and {sup 7}F{sub 2} states were recorded and then the crystal field parameters B{sub nm} were calculated assuming a C{sub 2v} site symmetry. The ratios B{sub 22}/B{sub 20} and B{sub 44}/B{sub 40} for each excitation energy within {sup 7}F{sub 0}-{sup 5}D{sub 0} transition were obtained and compared with the values calculated for Eu{sup 3+} in other types of glasses. -- Graphical abstract: Crystal fields parameters B{sub nm} of Eu{sup 3+} ions (strength, distribution) in novel TeO{sub 2}-TlO{sub 0.5}-ZnO glass system. Display Omitted

  14. Implementing SDG 15.3 on Land Degradation Neutrality in the EU and EU Member States

    NASA Astrophysics Data System (ADS)

    Wunder, Stephanie; Starke, Sue Martina; Frelih-Larsen, Ana; Kaphengst, Timo

    2017-04-01

    The continuing degradation of land and soils is a severe threat to the provision of ecosystem services and economic development. Sustainable use of land and soils are therefore an integral part of the "Agenda 2030" with its 17 Sustainable Development Goals (SDGs) and 169 targets adopted by the UNGeneral Assembly in September 2015. The SDGs provide new opportunities for an ambitious and integrated environmental policy worldwide and in the EU. Among the many relevant targets that directly or indirectly address soils (such as goals on zero hunger, well being, clean energy, climate change, water and sustainable cities), target 15.3 that aims to achieve "a land degradation-neutral world" by 2030 is the most relevant. The concept of "Land Degradation Neutrality" (LDN) is not only about halting the loss of healthy and fertile land, but also actively reversing degradation by restoring land in order to counterbal-ance losses that cannot be avoided. It is a very ambitious target but due to a lack of balancing mechanisms for degradation and restoration in most countries also a new concept. Land Degra-dation Neutrality therefore both needs a scientific conceptual framework as well as a political debate about its implementation and development of instruments. In the EU and its Member States, this debate can also serve as a catalyst to revive the discussion on a common soil policy in Europe after the withdrawal of the proposal for a soil framework directive in 2014. To analyze options for the implementation of target 15.3 in Germany and Europe the research project "Implementing the Sustainable Development Goals on Soils in Germany" (http://ecologic.eu/12876) is currently carried out by the Ecologic Institute on behalf of the Ger-man Environment Agency (UBA) and the German Federal Environment Ministry (BMUB). The project will run until spring 2017 and the session "European Environmental Policies and Sustainability" at the EGU will be an ideal opportunity to present the final

  15. Incorporation of lanthanide (Eu(3+)) ions in ZnS semiconductor quantum dots with a trapped-dopant model and their photoluminescence spectroscopy study.

    PubMed

    Wang, Yongbo; Liang, Xuhua; Liu, Enzhou; Hu, Xiaoyun; Fan, Jun

    2015-09-18

    Doping quantum dots (QDs) with lanthanide (Ln) ions is promising to modify the optical properties of QDs, but incorporating Ln(3+) ions into QD hosts remains a challenge. In this work, we adopt the trapped-dopant model for fabricating Eu-doped ZnS QDs via direct wet chemical synthesis. Sharp Eu dopant photoluminescence (PL) was observed in the PL spectra of the as-prepared Eu-doped ZnS QDs and the bands at ~590, ~618 and ~695 nm were assigned to transitions from (5)D0 to (7)F1, (7)F2 and (7)F4, respectively. Quenching of the ZnS bandgap PL and enhancement of the Eu dopant PL were observed with increasing Eu(3+) doping concentration, and also, the excitation spectra for Eu emission (618 nm) were similar to the typical excitonic features of the ZnS host. These spectroscopic results, as well as the XRD and EDS data, demonstrated that Eu(3+) ions were incorporated in the ZnS host rather than just on the surface, and the Eu dopant PL was derived from energy transfer from the QD host to Eu(3+) rather than direct excitation of Eu(3+). By surface passivation, the sharp Eu emission was well-separated from the ZnS bandgap emission, which led to a good signal-to-noise ratio for more sensitive detection.

  16. 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.

  17. Calibration of the EU Oxybarometer for Nakhlites

    NASA Technical Reports Server (NTRS)

    Makishima, J.; McKay, G.; Le, L.; Miyamoto; Mikouchi, T.

    2006-01-01

    Martian meteorites have various characteristics, which are direct clues to understanding the petrogenesis of Mars rocks. The variation in oxidation state among the Martian meteorites must have important implications for redox conditions of the Martian crust/mantle and overall differentiation on Mars. Wadhwa [1] and Herd et al. [2] reported that Martian basalts were formed under a range of oxidation states, suggesting complex petrogenesis processes. The nakhlites, which have rather different characteristics from basaltic shergottites, may give us additional clues to Martian petrogenesis. The oxidation states of meteorites are usually described by the oxygen fugacity (fO2) under which the meteorites crystallized. One of the methods to estimate the oxygen fugacity is the depth of Eu anomaly. Eu(2+)/Eu(3+) is determined by the oxygen fugacity and partitioning is different for Eu(2+) and Eu(3+). Therefore, the depth of Eu anomaly in a mineral is a function of the oxygen fugacity and the Eu2+/Eu3+ in the melt from which the mineral crystallized. This method has some advantages over another major method, the two-oxide oxybarometer [3], which can more easily be affected by subsolidus processes. The Eu oxybarometer can analyze the cores of the earliest formed crystals in Martian meteorites, which means it can give us a better indication of the oxygen fugacity of the parent melt. The calibration of the Eu oxybarometer has been done with the basaltic shergottites before [4]. However, it has never been applied to nakhlites (Oe et al. [5] measured the depth of Eu anomaly in the synthetic pyroxene only at QFM). Partition coefficients are strongly affected by phase compositions, especially pyroxene Ca content and melt Al content [e.g., 5,6]. The composition of nakhlite pyroxene is rather different from basaltic shergottite pyroxene. Thus, there may be problems in applying the Eu oxybarometer calibration for the basaltic shergottites [7] to nakhlites. Thus, we report in this

  18. Wood energy markets, 2010-2011

    Treesearch

    Francisco Aguilar; Christopher Gaston; Rens Hartkamp; Warren Mabee; Kenneth Skog

    2011-01-01

    Global wood energy markets continue to grow, driven primarily by demand in the EU and its commitment to meet 20% of energy consumption from renewable sources by 2020. Large investments in industrial pellet-production capacity have been made under expectations of a continuously growing demand, mainly from the EU. Concern about how energy and climate-change policies may...

  19. 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.

  20. 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.

  1. Catalytic reforming process

    SciTech Connect

    Swan, G.A.; Baird, W.C. Jr.

    1986-09-23

    In a process for improving the octane quality of a naphtha in a reforming unit comprised of a plurality of serially connected reactors, inclusive of one or more lead reactors and a tail reactor, each of which contains a platinum or platinum-rhenium catalyst, the naphtha flowing in sequence from one reactor of the series to another and contacting the catalyst at reforming conditions in the presence of hydrogen, the improvement is described which consists of: providing the tail reactor with a platinum-rhenium catalyst to which iridium has been added in amount sufficient to increase the C/sub 5/+ liquid yield via-a-vis a similar process utilizing in the tall reactor a platinum-rhenium catalyst to which no iridium has been added.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Medical malpractice tort reform.

    PubMed

    Ottenwess, David M; Lamberti, Meagan A; Ottenwess, Stephanie P; Dresevic, Adrienne D

    2011-01-01

    A tort is generally defined as a civil wrong which causes an injury, for which a victim may seek damages, typically in the form of money damages, against the alleged wrongdoer. An overview of the tort system is detailed, specifically in the context of a medical malpractice lawsuit, in order to provide a better understanding of the practical evolution of medical malpractice litigation and its proposed reforms. Rising premiums and defensive medicine are also discussed as part of the tort reform dialogue. Because medical malpractice litigation will never disappear entirely, implementing sound risk management and compliance programs are critical to every radiology department in order to improve the safety and quality of the care that its radiologists and technologists provide.

  7. 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.

  8. Spectral and Luminescent Properties of Oxyfluoride Glasses Codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+)

    NASA Astrophysics Data System (ADS)

    Vilejshikova, E. V.; Loiko, P. A.; Rachkovskaya, G. E.; Zakharevich, G. B.; Yumashev, K. V.

    2016-09-01

    The spectral and luminescent properties of SiO2-PbO-PbF2-CdF2 oxyfl uoride glasses doped with Yb3+, Eu3+, and Tb3+ were investigated. The lifetime τ( 5D0) of Eu3+ in glasses doped with Eu2O3 was 1.73 ms; τ( 5D4) of Tb3+, 2.25 ms. Intense red and green up-conversion luminescence due to cooperative energy transfer from Yb3+—Yb3+ pairs to Eu3+ and Tb3+ was observed for glasses codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+) upon excitation at 960 nm into the Yb3+ absorption band. Down-conversion luminescence of Yb3+ ions in the vicinity of ~1 μm was detected upon excitation by UV light of wavelength 355 nm.

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

    DOE PAGES

    Stand, L.; Zhuravleva, M.; Chakoumakos, Bryan C.; ...

    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

  10. 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.

  11. The Beida Reform

    ERIC Educational Resources Information Center

    Kewen, Shu

    2004-01-01

    Beida is always linked with a sort of fervor, a sort of moral behavior. Although it is not a world-class university, its connections with China's contemporary and modern history make it a great school. The direct motive behind the reform and the mapping out of its system is the pursuit of a sort of efficiency, but it is possible that what will be…

  12. 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.

  13. 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.

  14. Catalytic reforming process

    SciTech Connect

    Winter, W.E.; Markley, G.E.

    1984-04-03

    A process wherein, in a series of reforming zones, or reactors, each of which contains a bed, or beds of catalyst, the catalyst in the rearward most reforming zones is constituted of a high rhenium, platinum rhenium catalyst, viz., a catalyst comprising supported platinum and a relatively high concentration of rhenium relative to the platinum, and preferably the catalyst in the forwardmost reforming zone, or reactor of the series, is constituted of platinum, or platinum and a relatively low concentration of rhenium relative to the platinum. At least 30 percent, preferably from 40 percent to about 90 percent, of the rearward most reactors of the unit, or even 100 percent, based on the total weight of the catalyst in all of the reactors of the unit, contain a high rhenium, platinum rhenium catalyst, the weight ratio of rhenium:platinum being at least about 1.5:1. The beds of catalyst are contacted with a hydrocarbon or naphtha feed, and hydrogen, and the reaction continued for a period of at least 700 hours, preferably from about 700 hours to about 2750 hours, while conducting the reaction at temperatures ranging from about 850/sup 0/ F. to about 950/sup 0/ F. (E.I.T.), at pressures ranging from about 150 psig to about 350 psig, and at gas rates ranging from about 2500 SCF/B to about 4500 SCF/B.

  15. 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

    2016-09-06

    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.

  16. The first example of ab initio calculations of f-f transitions for the case of [Eu(DOTP)](5-) complex-experiment versus theory.

    PubMed

    Janicki, Rafał; Kędziorski, Andrzej; Mondry, Anna

    2016-10-12

    Crystal structures and photophysical properties (IR and UV-vis-NIR) of two compounds, [C(NH2)3]5[Eu(DOTP)]·12.5H2O and K5[Eu(DOTP)]·11H2O (DOTP = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis (methylenephosphonic acid)), were determined. The DOTP ligand is bonded to Eu(3+)via four O and four N atoms, filling thus eight coordination sites of Eu(3+). The experimental structures of two [K4Eu(DOTP)](-) clusters were used as a starting point for theoretical ab initio calculations based on a multireference wavefunction approach. Positions of the energy levels of the 4f(6) configuration of the Eu(3+) ion have been calculated and compared with those derived from the experimental spectra. This enabled us to tentatively assign energy levels of the Eu(3+) ion. The relationship between calculated energies of excited states and Eu-N and Eu-O bond lengths was discussed with respect to the nephelauxetic effect.

  17. Antiferromagnetism with divalent Eu in EuNi5As3

    NASA Astrophysics Data System (ADS)

    Jiang, W. B.; Smidman, M.; Xie, W.; Liu, J. Y.; Lee, J. M.; Chen, J. M.; Ho, S. C.; Ishii, H.; Tsuei, K. D.; Guo, C. Y.; Zhang, Y. J.; Lee, Hanoh; Yuan, H. Q.

    2017-01-01

    We have successfully synthesized single crystals of EuNi5As3 using a flux method, and we present a comprehensive study of the physical properties using magnetic susceptibility, specific heat, electrical resistivity, thermoelectric power, and x-ray absorption spectroscopy (XAS) measurements. EuNi5As3 undergoes two close antiferromagnetic transitions at respective temperatures of TN 1=7.2 K and TN 2=6.4 K, which are associated with the Eu2 + moments. Both transitions are suppressed upon applying a field, and we map the temperature-field phase diagrams for fields applied parallel and perpendicular to the easy a axis. XAS measurements reveal that the Eu is strongly divalent, with very little temperature dependence, indicating the localized Eu2 + nature of EuNi5As3 , with a lack of evidence for heavy-fermion behavior.

  18. Ferromagnetic behavior in mixed valence europium (Eu2+/Eu3+) oxide EuTi1-xMxO3 (M = Al3+ and Ga3+)

    NASA Astrophysics Data System (ADS)

    Akahoshi, Daisuke; Horie, Hiroki; Sakai, Shingo; Saito, Toshiaki

    2013-10-01

    We have investigated the Ti-site substitution effect on the magnetic properties of antiferromagnetic insulator EuTiO3 with a Néel temperature of ˜5 K. Partial substitution of Ti4+ with heterovalent Al3+ or Ga3+ turns the corresponding amount of magnetic Eu2+ into non-magnetic Eu3+. Both EuTi1-xAlxO3 (0.05 ≤ x ≤ 0.10) and EuTi1-xGaxO3 (0.05 ≤ x ≤ 0.10) exhibit ferromagnetic (FM) insulating behavior below ˜4 K. The Eu2+/Eu3+ mixed valence state probably contributes to the emergence of the FM behavior. Fine control of the magneto-electric (ME) phases of EuTi1-xAlxO3 and EuTi1-xGaxO3 would lead to intriguing ME phenomena such as giant ME effect.

  19. 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.

  20. 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.

  1. Eu3+-doped wide band gap Zn2SnO4 semiconductor nanoparticles: Structure and luminescence

    DOE PAGES

    Dimitrievska, Mirjana; Ivetić, Tamara B.; Litvinchuk, Alexander P.; ...

    2016-08-03

    Nanocrystalline Zn2SnO4 powders doped with Eu3+ ions were synthesized via a mechanochemical solid-state reaction method followed by postannealing in air at 1200 °C. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Raman and photoluminescence (PL) spectroscopies provide convincing evidence for the incorporation of Eu3+ ions into the host matrix on noncentrosymmetric sites of the cubic inverse spinel lattice. Microstructural analysis shows that the crystalline grain size decreases with the addition of Eu3+. Formation of a nanocrystalline Eu2Sn2O7 secondary phase is also observed. Luminescence spectra of Eu3+-doped samples show several emissions, including narrow-band magnetic dipole emission at 595 nm and electric dipolemore » emission at 615 nm of the Eu3+ ions. Excitation spectra and lifetime measurements suggest that Eu3+ ions are incorporated at only one symmetry site. According to the crystal field theory, it is assumed that Eu3+ ions participate at octahedral sites of Zn2+ or Sn4+ under a weak crystal field, rather than at the tetrahedral sites of Zn2+, because of the high octahedral stabilization energy for Eu3+. Activation of symmetry forbidden (IR-active and silent) modes is observed in the Raman scattering spectra of both pure and doped samples, indicating a disorder of the cation sublattice of Zn2SnO4 nanocrystallites. These results were further supported by the first principle lattice dynamics calculations. The spinel-type Zn2SnO4 shows effectiveness in hosting Eu3+ ions, which could be used as a prospective green/red emitter. As a result, this work also illustrates how sustainable and simple preparation methods could be used for effective engineering of material properties.« less

  2. Integrated reforming/aromatization process

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1990-06-26

    This patent describes an integrated process for increasing the gasoline yield from a catalytic reforming process. It comprises: charging a naphtha boiling range feedstream to a catalytic reforming reaction zone under reforming conversion conditions; withdrawing a reactor effluent stream from the reforming reaction zone; separating the reactor effluent stream into a hydrogen-rich gas stream and an unstabilized reformate stream; further separating the unstabilized reformate in a fractionator into an overhead stream containing C{sub 4} - components and a bottom stream containing C{sub 6} + components; charging the fractionator overhead stream to a catalytic aromatization zone under aromatization conversion conditions; withdrawing an aromatization zone effluent stream from the aromatization zone; cooling the aromatization zone effluent stream; separating the cooled aromatization zone effluent steam into a C{sub 4} - stream and a C{sub 5} + stream; and refluxing the C{sub 5} + aromatic gasoline stream to the fractionation zone.

  3. Deposition and characterization of luminescent Eu(tta)3phen-doped parylene-based thin-film materials.

    PubMed

    Maggioni, Gianluigi; Campagnaro, Antonio; Tonezzer, Michele; Carturan, Sara; Quaranta, Alberto

    2013-06-24

    Herein, novel host-guest films produced by coarse vacuum cosublimation of the parylene C dimer and Eu(tta)3phen are prepared and studied. Eu(tta)3phen sublimation at different temperatures allows films with different concentrations of the Eu complex to be obtained. The films are characterized by Rutherford backscattering spectrometry (RBS), FTIR spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), and UV/Vis absorption and emission spectroscopy. RBS, FTIR, and XRD reveal the incorporation of Eu(tta)3phen into the parylene matrix. AFM evidences the very flat film surface, which is particularly advantageous for optical applications. UV/Vis absorption and emission analyses confirm that the optical properties of Eu(tta)3phen are preserved in the deposited films. Fluorescence measurements evidence the occurrence of an energy-transfer process between parylene and Eu(tta)3phen, and this results in an increase in the light emitted by the Eu complex that is as much as five times higher than that emitted by Eu(tta)3phen alone.

  4. 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).

  5. 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

  6. Energy

    ERIC Educational Resources Information Center

    Boyer, Ernest L.

    1977-01-01

    Schools must teach pupils about the wide nature of our energy dilemma and prepare them for a future in which not only will conservation of energy be essential, but also the conservation and preservation of our total natural resources. (JD)

  7. 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.

  8. Structure and thermoelectric properties of EuTi(O,N)3 ± δ

    NASA Astrophysics Data System (ADS)

    Sagarna, L.; Rushchanskii, K. Z.; Maegli, A.; Yoon, S.; Populoh, S.; Shkabko, A.; Pokrant, S.; Ležaić, M.; Waser, R.; Weidenkaff, A.

    2013-07-01

    After partial substitution of nitrogen for oxygen in EuTiO3, the crystal structure, thermoelectric properties, morphology, and electronic structure of the products were analyzed and compared with pristine EuTiO3. The space group of EuTi(O,N)3 ± δ was orthorhombic Pnma due to the tilt and rotation of the anion octahedra, compared to cubic Pm3¯m of EuTiO3 (at room temperature). The thermoelectric properties of oxynitride polycrystalline bodies sintered in three different ways were investigated in the temperature range of 300 K < T < 950 K. The Seebeck coefficients (S) of the oxynitrides were lower compared with the oxide, and the electrical resistivities (ρ) were increased about one order of magnitude. The activation energies (EA) indicated a larger band gap of EuTi(O,N)3 ± δ when compared to the pristine EuTiO3 (˜1.3 eV compared to 0.98 eV). A morphological characterization by transmission electron microscopy and scanning electron microscopy illustrated intrinsic nanopores within the individual particles and weak grain-interconnections indicating poor intergrain electron transport. Ab initio calculations of the electronic structures confirmed a larger band gap of the distorted crystal structure of the oxynitride and showed a decrease of the density of states at the Fermi level, explaining the reduction of the measured S.

  9. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance[].

    PubMed

    Moore, Evan G; D'Aléo, Anthony; Xu, Jide; Raymond, Kenneth N

    2009-10-13

    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 center. The synthesis and the complexation of Ln(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(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)](-)) 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 (DTPA) at pH= 7.4. This Eu(III) complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH= 7.4) when compared to 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)](-). This overall improvement was achieved by saturating the coordination sphere of the Eu(III) cation, yielding an increased metal centered efficiency by excluding solvent water molecules from the metal's inner sphere.

  10. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance[1

    PubMed Central

    Moore, Evan G.; D’Aléo, Anthony; Xu, Jide; Raymond, Kenneth N.

    2010-01-01

    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 center. The synthesis and the complexation of Ln(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(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)]−) 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 (DTPA) at pH= 7.4. This Eu(III) complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH= 7.4) when compared to 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)]−. This overall improvement was achieved by saturating the coordination sphere of the Eu(III) cation, yielding an increased metal centered efficiency by excluding solvent water molecules from the metal’s inner sphere. PMID:20543961

  11. Enhanced photoluminescence in CaMoO4:Eu3+ by Gd3+ co-doping.

    PubMed

    Singh, B P; Parchur, A K; Ningthoujam, R S; Ansari, A A; Singh, P; Rai, S B

    2014-03-28

    We have studied the luminescence property of CaMoO4:Eu(3+). The emission peaks at 590 ((5)D0→(7)F1) and 613 nm ((5)D0→(7)F2) for Eu(3+) are observed after excitation at 266 nm (i.e. Mo-O charge transfer band). The peak intensity of the latter dominates over the former indicating an asymmetric environment of Eu(3+) in EuO8 polyhedron or parity mixing. Luminescence intensity increases significantly with co-doping of Gd(3+). This is ascribed to energy transfer from Mo-O/Gd(3+) to Eu(3+). Luminescence intensity increases with annealing up to 900 °C due to the extent of decrease of non-radiative rates. Very high asymmetric values (A21) of 12-16 are found indicating a red emitter. As-prepared samples are dispersible in polar solvents like water, ethanol, methanol, dimethyl sulfoxide (DMSO) and ethylene glycol (EG); and among them, optimum luminescence is found in methanol. Polymer film shows red emission. The quantum yields of as-prepared 2 and 10 at% Gd(3+) co-doped CaMoO4:Eu(3+) under 277 nm (UV excitation) are 21 and 80%, respectively.

  12. 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.

  13. 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.

  14. Anomalous Eu valence state and superconductivity in undoped Eu3Bi2S4F4.

    PubMed

    Zhai, Hui-Fei; Zhang, Pan; Wu, Si-Qi; He, Chao-Yang; Tang, Zhang-Tu; Jiang, Hao; Sun, Yun-Lei; Bao, Jin-Ke; Nowik, Israel; Felner, Israel; Zeng, Yue-Wu; Li, Yu-Ke; Xu, Xiao-Feng; Tao, Qian; Xu, Zhu-An; Cao, Guang-Han

    2014-10-29

    We have synthesized a novel europium bismuth sulfofluoride, Eu3Bi2S4F4, by solid-state reactions in sealed evacuated quartz ampules. The compound crystallizes in a tetragonal lattice (space group I4/mmm, a = 4.0771(1) Å, c = 32.4330(6) Å, and Z = 2), in which CaF2-type Eu3F4 layers and NaCl-like BiS2 bilayers stack alternately along the crystallographic c axis. There are two crystallographically distinct Eu sites, Eu(1) and Eu(2) at the Wyckoff positions 4e and 2a, respectively. Our bond valence sum calculation, based on the refined structural data, indicates that Eu(1) is essentially divalent, while Eu(2) has an average valence of ∼ +2.64(5). This anomalous Eu valence state is further confirmed and supported, respectively, by Mössbauer and magnetization measurements. The Eu(3+) components donate electrons into the conduction bands that are mainly composed of Bi 6px and 6py states. Consequently, the material itself shows metallic conduction and superconducts at 1.5 K without extrinsic chemical doping.

  15. U.S.-EU Cooperation Against Terrorism

    DTIC Science & Technology

    2010-07-09

    United States and the EU have pledged to enhance international information exchanges on lost and stolen passports and to promote travel document...Scanners,” Deutsche Welle, January 21, 2010. 10 “U.S. Conciliatory in Air Marshal Demands,” Associated Press, April 26, 2004; John M. Doyle, “U.S., EU To...and other interested states) to qualify. Among other measures, P.L. 110-53 called on VWP participants to meet certain security and passport

  16. U.S.-EU Cooperation Against Terrorism

    DTIC Science & Technology

    2014-12-01

    information systems.7 In addition, EU policy makers have been holding discussions with Internet and social media companies such as Google, Twitter...Hamas-related charities to its common terrorist list because some EU members view them as separate entities engaged in political or social work.24...viewed Hezbollah as providing needed social services in some of Lebanon’s poorest communities. On the other hand, critics of Hezbollah’s absence

  17. Health reform: a bipartisan view.

    PubMed

    Cooper, Jim; Castle, Michael

    2009-01-01

    This optimistic assessment of the prospects for health reform from senior Democratic and Republican congressmen spells out several reasons why reform can be achieved early in the first year of the Obama administration. Political and policy factors suggest that President-elect Barack Obama is in a much better position than his predecessors to achieve comprehensive health reform, including universal coverage. The Obama administration will have to overcome numerous obstacles and resistance to enact reform. Still, after decades of frustration and disappointment, policymakers should set aside their differences and enable the United States to join the ranks of developed nations by making sure every American has health insurance.

  18. [Health reform in the USA].

    PubMed

    Ganduglia, Cecilia

    2010-01-01

    The United States of America passed early this year the bill enforcing their health reform. this reform aims at achieving universal insurance, cost containment and improving quality of care. The debate around this reform has been long and unable to arrive to an agreement between the parts. Even if the expansion in the medical coverage system does not reduce to zero the current degree of inaccessibility to the health system, these achievements could be considered a very important first step. Nonetheless, chances are that this reform will continue being as polemic as the negotiations previous to its conception.

  19. 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.

  20. 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.

  1. 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 PAGES

    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

  2. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. 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.

  9. Heat-treatment controlled structural and optical properties of sol-gel fabricated Eu:ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ghosh, Subhabrata; Uma Mahendra Kumar, K.; Bhaktha, B. N. Shivakiran

    2017-02-01

    We report on the fabrication of sol-gel derived Eu-doped ZnO films and the effects of heat-treatment on their structural and optical properties. X-ray diffraction data analysis confirms the decrease in strain in the thin films with increasing heat-treatment temperatures, and the compressive stress of the samples is found to become tensile for heat-treatments between 650 °C and 800 °C. X-ray-absorption fine-structure spectra performed at the Eu L3-edge confirm the absence of clustering of Eu-ions. The photoluminescence (PL) spectra of undoped and doped films consist of near-band edge emissions along with the defect state emissions of ZnO. Intense red emission (612 nm) is observed under UV excitation attributed to the 5D0 →7F2 energy level transition of Eu3+ ions in the doped films. The elemental composition and the existence of Eu2+ as well as Eu3+ has been discussed with the help of X-ray photoelectron spectroscopy. ZnO → Eu3+ energy transfer has also been confirmed with the help of PL excitation spectra in these transparent ZnO thin films for applications in integrated optic devices operating in the UV-visible region.

  10. Health care reform 2010: a fresh view on tort reform.

    PubMed

    Stimson, C J; Dmochowski, Roger; Penson, David F

    2010-11-01

    We reviewed the state of medical malpractice tort reform in the context of a new political climate and the current debate over comprehensive health care reform. Specifically we asked whether medical malpractice tort reform is necessary, and evaluated the strengths and weaknesses of contemporary reform proposals. The medical, legal and public policy literature related to medical malpractice tort reform was reviewed and synthesized. We include a primer for understanding the current structure of medical malpractice law, identify the goals of the current system and analyze whether these goals are presently being met. Finally, we describe and evaluate the strengths and weaknesses of the current reform proposals including caps on damages, safe harbors and health care courts. Medical malpractice tort law is designed to improve health care quality and appropriately compensate patients for medical malpractice injuries, but is failing on both fronts. Of the 3 proposed remedies, caps on damages do little to advance the quality and compensatory goals, while safe harbors and health care courts represent important advancements in tort reform. Tort reform should be included in the current health policy debate because the current medical malpractice system is not adequately achieving the basic goals of tort law. While safe harbors and health care courts both represent reasonable remedies, health care courts may be preferred because they do not rely on jury determination in the absence of strong medical evidence. Copyright © 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  11. Eu(2+) luminescence in strontium aluminates.

    PubMed

    Dutczak, D; Jüstel, T; Ronda, C; Meijerink, A

    2015-06-21

    The luminescence properties of Eu(2+) doped strontium aluminates are reported and reviewed for a variety of aluminates, viz. SrAl12O19, SrAl4O7, Sr4Al14O25, SrAl2O4 and Sr3Al2O6. The aim of the research is to investigate the role of local coordination and covalency of the aluminate host lattice, related to the Sr/Al ratio, on the optical properties of the Eu(2+) ion. The UV and VUV excited luminescence spectra as well as luminescence decay curves were recorded to characterize the luminescence properties of the investigated aluminates. The emission of Eu(2+) ions varies over a wide spectral range, from ultraviolet (UV) to red, for the series of aluminates. The variation in emission color can be related to the crystal-field splitting of the 5d levels and the covalent interaction with the surrounding oxygen anions. In the least covalent material, viz. SrAl12O19:Eu(2+), narrow line emission due to the (6)P7/2-(8)S7/2 transition occurs at 4 K, indicating that the 4f(6)5d excited state is situated above the (6)P7/2(4f(7)) excited state around 360 nm. The most alkaline material, viz. Sr3Al2O6:Eu(2+) is the most covalent host and exhibits several d-f emission bands in the yellow to red spectral range due to the Eu(2+) ions located on different crystallographic Sr(2+) sites. The Eu(2+) emission spectra in the other aluminates confirm the trend that with increasing Sr/Al ratio the Eu(2+) emission shifts to longer wavelengths. Interesting differences are observed for the Eu(2+) from different crystallographic sites which cannot always be related with apparent differences in the first oxygen coordination sphere. The discussion gives insight into how in a similar class of materials, strontium aluminates, the emission color of Eu(2+) can be tuned over a wide spectral region.

  12. Persistent luminescence of CaMgSi2O6:Eu(2+),Dy(3+) and CaMgSi2O6:Eu(2+),Ce(3+) phosphors prepared using the solid-state reaction method.

    PubMed

    Chandrakar, P; Baghel, R N; Bisen, D P; Chandra, B P

    2016-02-01

    CaMgSi2O6:Eu(2+),Dy(3+) and CaMgSi2O6:Eu(2+),Ce(3+) phosphors were synthesized using the solid-state reaction method. X-Ray diffraction (XRD) and photoluminescence (PL) analyses were used to characterize the phosphors. The XRD results revealed that the synthesized CaMgSi2O6:Eu(2+),Dy(3+) and CaMgSi2O6:Eu(2+),Ce(3+) phosphors were crystalline and are assigned to the monoclinic structure with a space group C2/c. The calculated crystal sizes of CaMgSi2O6:Eu(2+),Dy(3+) and CaMgSi2O6:Eu(2+),Ce(3+) phosphors with a main (221) diffraction peak were 44.87 and 53.51 nm, respectively. Energy-dispersive X-ray spectroscopy (EDX) confirmed the proper preparation of the sample. The PL emission spectra of CaMgSi2O6:Eu(2+),Dy(3+) and CaMgSi2O6:Eu(2+),Ce(3+) phosphors have a broad band peak at 444.5 and 466 nm, respectively, which is due to electronic transition from 4f(6) 5d(1) to 4f(7). The afterglow results indicate that the CaMgSi2O6:Eu(2+),Dy(3+) phosphor has better persistence luminescence than the CaMgSi2O6:Eu(2+),Ce(3+) phosphor. Copyright © 2015 John Wiley & Sons, Ltd.

  13. Introducing Eu2+ into yellow phosphor LiBaB9O15:Ce3+, Dy3+ as blue emitting source to realize white emission

    NASA Astrophysics Data System (ADS)

    Li, Ting; Li, Panlai; Fu, Nian; Wang, Zhijun; Xu, Shuchao; Bai, Qiongyu; Yang, Zhiping

    2017-04-01

    A series of Dy3+, Ce3+/Dy3+, Eu2+/Dy3+ and Ce3+/Eu2+/Dy3+ doping LiBaB9O15 (LBB) phosphors were synthesized via a high temperature solid-state method. LBB:Dy3+ cannot create light under ultraviolet radiation, however, LBB:Ce3+, Dy3+ can produce yellow emission under 295 nm excitation. The energy transfer occurs from Ce3+ to Dy3+ ions via electric dipole-dipole interaction and the critical distance is estimated to be 21.15 Å based on concentration quenching model. Generally, Eu2+ ion is a sensitizer to Dy3+ ion, however, there is only the emission of Eu2+ in LBB:Eu2+, Dy3+, which means there is no energy transfer from Eu2+ to Dy3+ ions. Interestingly enough, when doping Eu2+ ion into LBB:Ce3+, Dy3+, white emission can be achieved by increase the blue (350-425 nm) emission intensity. The spectral property, quantum efficiency, CIE chromaticity coordinates and thermal quenching property of LBB:Ce3+, Eu2+, Dy3+ are investigated. The results indicate that LBB:Ce3+, Eu2+, Dy3+ may be a potential application to white light emitting diodes.

  14. 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.

  15. Fuel Reformer Nozzle Development

    NASA Technical Reports Server (NTRS)

    Lai, Ming-Chia D.

    2003-01-01

    The fellowship work this summer will be in support of the development of a fuel mixer for a liquid fuel reformer that is upstream of a fuel cell. Tasks for the summer shall consist of design of a fuel mixer, setup of the laser diagnostics for determining the degree of fuel mixing, and testing of the fuel mixer. The fuel mixer shall be a venturi section with fuel injected at or near the throat, and an air swirler upstream of the venturi. Data to determine the performance of the mixer shall be taken using a Phase Doppler Particle Analyzer (PDPA).

  16. Fuel Reformer Nozzle Development

    NASA Technical Reports Server (NTRS)

    Lai, Ming-Chia D.

    2003-01-01

    The fellowship work this summer will be in support of the development of a fuel mixer for a liquid fuel reformer that is upstream of a fuel cell. Tasks for the summer shall consist of design of a fuel mixer, setup of the laser diagnostics for determining the degree of fuel mixing, and testing of the fuel mixer. The fuel mixer shall be a venturi section with fuel injected at or near the throat, and an air swirler upstream of the venturi. Data to determine the performance of the mixer shall be taken using a Phase Doppler Particle Analyzer (PDPA).

  17. Energy

    DTIC Science & Technology

    2003-01-01

    Canada, Britain, and Spain. We found that the energy industry is not in crisis ; however, U.S. government policies, laws, dollars, and even public...CEIMAT (Centro de Investagaciones Energeticas , Medioambeintales y Tecnologicas) Research and development Page 3 of 28ENERGY 8/10/04http://www.ndu.edu...procurement or storage of standard, common use fuels. NATURAL GAS Natural gas, abundant globally and domestically, offers energy versatility among

  18. 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.

  19. 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:…

  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. Implementing Comprehensive Reform: Implications for Practice

    ERIC Educational Resources Information Center

    Stout, Karen A.

    2016-01-01

    This chapter describes the challenges and practical barriers community colleges face when implementing comprehensive reform, exploring how reforms are leading to some improvements but not often scaled improvements.

  2. Implementing Comprehensive Reform: Implications for Practice

    ERIC Educational Resources Information Center

    Stout, Karen A.

    2016-01-01

    This chapter describes the challenges and practical barriers community colleges face when implementing comprehensive reform, exploring how reforms are leading to some improvements but not often scaled improvements.

  3. 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.

  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. Recent University Reform in Mexico.

    ERIC Educational Resources Information Center

    Ornelas, Carlos; Post, David

    1992-01-01

    Examination of recent reforms at three Mexican public universities suggests that university administrators have had little will or power to regulate expansion in the face of growing social demand for higher education. Discusses "populist" and "modernist" conceptions of university reform, which focus on social needs and economic…

  6. 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…

  7. 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,…

  8. 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…

  9. 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…

  10. Rural Dimensions of Welfare Reform.

    ERIC Educational Resources Information Center

    Weber, Bruce A., Ed.; Duncan, Greg J., Ed.; Whitener, Leslie A., Ed.

    The 16 chapters in this five-part book, each by different authors, trace the effects of welfare reform (mandated by the Personal Responsibility and Work Opportunity Reconciliation Act of 1996), upon poor people in rural areas of the United States. The book begins with an introduction called "As the Dust Settles: Welfare Reform and Rural…

  11. Rural Dimensions of Welfare Reform.

    ERIC Educational Resources Information Center

    Weber, Bruce A., Ed.; Duncan, Greg J., Ed.; Whitener, Leslie A., Ed.

    The 16 chapters in this five-part book, each by different authors, trace the effects of welfare reform (mandated by the Personal Responsibility and Work Opportunity Reconciliation Act of 1996), upon poor people in rural areas of the United States. The book begins with an introduction called "As the Dust Settles: Welfare Reform and Rural…

  12. 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…

  13. Panel on "Teacher Education Reform."

    ERIC Educational Resources Information Center

    Imig, David G.

    There has been a growing but begrudging recognition that better teacher education is necessary both to carry out other education-related reforms and to provide knowledge for shaping the reform agenda. Without fundamental changes in the ways that teachers teach, changes will not occur in the learning outcomes of a particular lesson or class or…

  14. 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…

  15. Compensation Reform in the Schools

    ERIC Educational Resources Information Center

    Laine, Sabrina; Potemski, Amy; Rowland, Cortney

    2010-01-01

    One of the most frequently discussed topics in education reform circles is teacher pay--how much money teachers make, for what work and who decides teachers' salaries. Over time, educator pay reform has included many different reward structures and goes by as many different names, such as merit pay, performance pay and differentiated pay. The…

  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. 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…

  18. The Futures of School Reform

    ERIC Educational Resources Information Center

    Mehta, Jal, Ed.; Schwartz, Robert B., Ed.; Hess, Frederick M., Ed.

    2012-01-01

    "The Futures of School Reform" represents the culminating work of a three-year discussion among national education leaders convened by the Harvard Graduate School of Education. Based on the recognition that current education reform efforts have reached their limits, the volume maps out a variety of bold visions that push the boundaries…

  19. 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…

  20. 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…