Bimodal Nd-doped luVo4 nanoprobes functionalized with polyacrilic acid for x-ray computed tomography and NIR luminescent imaging

Uniform Nd3+-doped LuVO4 nanophosphors have been synthesized for the first time in literature by using a poliol-based method at 120 °C from Nd3+ and vanadate precursors. After optimizing the Nd doping level, these phosphors present intense luminescence in the near-infrared biological windows. The X-ray attenuation capacity of the optimum nanophosphor has been found to be higher than that of a commercial X-ray computed tomography contrast agent. After surface coating with polyacrylic acid, such nanoparticles present high colloidal stability in physiological pH medium and high cell viability. Because of these properties, the developed Nd3+-doped LuVO4 nanoparticles have potential applications as a bimodal probe for NIR luminescent bioimaging and X-ray computed tomography

Food and nutrition security discursive frames in the context of the Spanish economic crisis

[EN] The recent economic crisis in Spain has provoked a number of food and nutrition security (FNS) impacts that have fuelled a fragmented landscape of food-related debates, although these have not taken the form of a coherent and allembracing public discussion on national food security. This paper is an inductive analysis of such debates, mostly based on media coverage, in an attempt to disentangle the different discourse frames on FNS in Spain, and the role played by the economic crisis in the shaping and underpinning of such frames. For this purpose a frame matrix was constructed, paying particular attention to the stakeholders governance claims in order to confront frame-specific problems. Results show how stakeholders have used elements of the crisis to underpin or reinterpret their core arguments. In addition, governance claims have concentrated on the malfunctioning of the food chain, mostly due to unequal bargaining power, and the way this could be putting at risk crucial components of the food system and future FNS. Also, the short-termism of most stakeholders approaches obscures the long run threats to the Spanish food system.This research is part of the project "Assessment of the impact of global drivers of change on Europe's food security" (TRANSMANGO), granted by the EU under 7th Framework Programme, theme KBBE.2013.2.5-01, Grant agreement no: 613532. Authors gratefully appreciate the comments and suggestions made by the three anonymous reviewers and the editors of the Journal.OOrtiz Miranda, D.; Moreno Pérez, OM.; Arnalte Alegre, EV. (2016). Food and nutrition security discursive frames in the context of the Spanish economic crisis. Food Security. 8(3):665-677. https://doi.org/10.1007/s12571-016-0574-xS66567783Antentas, J. M., & Vivas, E. (2014). 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Energy transfer efficiency in YF3 nanocrystals: Quantifying the Yb31 to Tm31 infrared dynamics

efficiency in YF3:Yb3þ/Tm3þ nanocrystals through the study of Yb3þ dynamics. The obtained results are compared to those previously reported in macrocrystals to analyze possible changes related to size reduction. Luminescence lifetimes are much shorter in the nanoparticles than in bulk samples, a behavior that can be related to Yb3þ ! Yb3þ migration and the enhanced surface/volume ratio of the nanoparticles. On the other hand, Yb3þ ! Tm3þ energy transfer macroparameter remains unaltered, demonstrating that spectroscopic intrinsic parameters such as radiative and non-radiative probabilities are not affected by size reduction. Finally, a formula that describes Yb3þ lifetime dependence with Yb3þ and Tm3þ concentration is proposed, considering both the effects produced by migration between Yb3þ ions and energy transfer from Yb3þ to Tm3þ ions.Peer reviewe

Experimental determination of the luminescent quantum efficiency of the laser emitting level of

The luminescent quantum efficiency of the laser emitting level (${}^4F_{3/2}$) of $\rm Nd^{3+}$ ions in lithium niobate ($\rm LiNbO_3$) is obtained experimentally by using a method based on the simultaneous and multiwavelength measurement of photoacoustic and luminescent signals after modulated continuous laser excitation. The experimental results give a high luminescence quantum efficiency, $\Phi = 0.98$ ($\Delta\Phi = 0.08$), which is in agreement with the highest of the values reported in the literature from Judd-Ofelt calculations

Synthesis of spherical down- and up-conversion NaYF4-based nanophosphors with tunable size in ethylene glycol without surfactants or capping additives

A very simple route for the synthesis of spherical down-conversion (DC) and up-conversion (UC) NaYF4-based nanophosphors is described which consists of a precipitation reaction at rather low temperature (max. 120 °C) from solutions containing sodium fluoride and appropriate Ln precursors in a common solvent (ethylene glycol/water mixtures), without the use of any other additive (complexing agent or surfactant). The role played by the nature of the yttrium precursor and the solvent on the morphological characteristics of the nanoparticles is discussed. The size of the nanospheres, which crystallized in the cubic α-NaYF4 phase, could be tuned within the 45-155 nm range by adjusting the reaction parameters (temperature and ethylene glycol/water ratio). The applicability of this method is illustrated for the synthesis of EuIII-doped (DC), TbIII-doped (DC) and YbIII/ErIII codoped (UC) NaYF4 nanophosphors, whose luminescent properties were also analysed. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008.Peer Reviewe