Publications by authors named "Eric Gautron"

20 Publications

  • Page 1 of 1

Design of metastable oxychalcogenide phases by topochemical (de)intercalation of sulfur in LaOS.

Nat Commun 2021 Jun 14;12(1):3605. Epub 2021 Jun 14.

Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, Nantes, F-44000, France.

Designing and synthesising new metastable compounds is a major challenge of today's material science. While exploration of metastable oxides has seen decades-long advancement thanks to the topochemical deintercalation of oxygen as recently spotlighted with the discovery of nickelate superconductor, such unique synthetic pathway has not yet been found for chalcogenide compounds. Here we combine an original soft chemistry approach, structure prediction calculations and advanced electron microscopy techniques to demonstrate the topochemical deintercalation/reintercalation of sulfur in a layered oxychalcogenide leading to the design of novel metastable phases. We demonstrate that LaOS may react with monovalent metals to produce sulfur-deintercalated metastable phases LaOS and oA-LaOS whose lamellar structures were predicted thanks to an evolutionary structure-prediction algorithm. This study paves the way to unexplored topochemistry of mobile chalcogen anions.
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http://dx.doi.org/10.1038/s41467-021-23677-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8203606PMC
June 2021

Toward the Coordination Fingerprint of the Edge-Sharing BO Tetrahedra.

Inorg Chem 2021 Feb 21;60(4):2406-2413. Epub 2021 Jan 21.

Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, F-44000 Nantes, France.

The KSbBO (KSBO) material undergoes an uncommon symmetry increase upon cooling, from triclinic symmetry at room temperature to monoclinic symmetry at low temperature. The first-order phase transition is accompanied by shrinkage of the unit cell, resulting in the transformation of every pair of head-to-tail triangular BO groups into one BO unit featuring unique edge-sharing BO tetrahedra. This is the first material with BO units formed through temperature lowering and exhibiting a B-O anionic framework composed uniquely of isolated edge-sharing BO tetrahedra. Several techniques including single-crystal X-ray diffraction experiments, Raman and B magic-angle-spinning NMR spectroscopies, and, for the first time, B K-edge electron energy loss spectroscopy were used to evidence the rare and discrete BO units. The complete transformation of BO units into BO units makes the KSBO compound the perfect candidate to extract information about BO units whose signal can be unambiguously assigned.
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http://dx.doi.org/10.1021/acs.inorgchem.0c03272DOI Listing
February 2021

Layered Quaternary Compounds in the CuS-InS-GaS system.

Inorg Chem 2020 Apr 18;59(7):4546-4553. Epub 2020 Mar 18.

Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, F-44000 Nantes, France.

Several new materials with four structure-types (e.g., CuInGaS (CIGS), CuInGaS (CIGS), CuInGaS (CIGS), and CuInGaS (CIGS)) have been evidenced in the CuS-InS-GaS pseudo-ternary system. All of them present a 2D structure built upon infinite 2/∞[InS] layers ((InS) octahedra sharing edges) on which condense on both sides mono-, bi-, or tri-2/∞[MS] layers ((MS) tetrahedra (M = Cu, In, Ga) sharing corners). (M(Td))(In(Oh))S slabs are separated from each other by a van der Waals gap, and subscript refers to the number of sulfur layers within the building block. These compounds have the propensity to display stacking faults but also polymorphic forms. Their optical gap (ca. 1.7 eV) is quite similar to the one of the Cu(InGa)S chalcopyrite absorbers used in tandem solar cells, and the major charge carriers are holes. This suggests that they might be very attractive for photovoltaic applications in thin film devices but also for photocatalysis.
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http://dx.doi.org/10.1021/acs.inorgchem.9b03686DOI Listing
April 2020

Impact of Nanostructuration on the Chemical Composition of Nickel Oxide Nanoparticles.

Inorg Chem 2019 Nov 25;58(22):15004-15007. Epub 2019 Oct 25.

Institut des Matériaux Jean Rouxel , Université de Nantes, CNRS , 2 rue de la Houssinière , 44322 Nantes Cedex 03 , France.

Reduction of the size of a particle down to a few tens of nanometers or below may drastically affect its physical properties. That is well-known for quantum dots. Conversely, many works consider the chemical composition of nanoparticles as invariant upon reduction of their dimension. Here we demonstrate that the chemical composition of a transition-metal oxide, namely, nickel oxide, is drastically affected by its nanostructuration.
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http://dx.doi.org/10.1021/acs.inorgchem.9b02088DOI Listing
November 2019

Near interface ionic transport in oxygen vacancy stabilized cubic zirconium oxide thin films.

Phys Chem Chem Phys 2018 Nov 11;20(41):26068-26071. Epub 2018 Oct 11.

Department of Energy Conversion and Storage, Technical University of Denmark, DTU Risø Campus, DK-4000 Roskilde, Denmark.

The cubic phase of pure zirconia (ZrO) is stabilized in dense thin films through a controlled introduction of oxygen vacancies (O defects) by cold-plasma-based sputtering deposition. Here, we show that the cubic crystals present at the film/substrate interface near-region exhibit fast ionic transport, which is superior to what is obtained with similar yttrium-stabilized cubic zirconia thin films.
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http://dx.doi.org/10.1039/c8cp05465gDOI Listing
November 2018

Evaluation of the content of TiO nanoparticles in the coatings of chewing gums.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2018 Feb 20;35(2):211-221. Epub 2017 Oct 20.

a UR1268 BIA (Biopolymères Interactions Assemblages), INRA , Nantes , France.

Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO, the estimated intakes of TiO nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO. The coatings of four kinds of chewing gum, where the presence of TiO was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO varies from one coating to another. TiO particles constitute the entire coating of some chewing gums, whereas for others, TiO particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO per piece of chewing gum. These data should serve to refine the exposure scenario.
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http://dx.doi.org/10.1080/19440049.2017.1384576DOI Listing
February 2018

Silica nanofibers as a new drug delivery system: a study of the protein-silica interactions.

J Mater Chem B 2017 Apr 3;5(16):2908-2920. Epub 2017 Apr 3.

INSERM, UMRS 1229, RMeS "Regenerative Medicine and Skeleton", Team STEP "Physiopathology and joint regenerative medicine", Nantes, France.

Drug delivery systems are proposed for the in situ controlled delivery of therapeutic molecules in the scope of tissue engineering. We propose herein silica nanofibers as carriers for the loading and release of bioactive proteins. The influence of pH, time and concentration on the amount of adsorbed proteins was studied. The interactions allowing loading were then studied by means of electron microscopy, zeta potential measurements, electron energy loss spectroscopy and attenuated total reflectance Fourier transform infrared analysis. Release profiles were determined and biological activities were enzymatically assessed. The first part of the work was carried out with lysozyme as a model protein, and then bioactive growth factors TGF-β1 and GDF-5 were used because their significance in human adipose stromal cell differentiation towards intervertebral disc nucleopulpocytes was previously assessed. It is demonstrated that protein-silica nanofiber interactions are mainly driven by hydrogen bonds and local electrostatic interactions. The present data thus provide a better understanding of the adsorption phenomenon involved, as well as a method to control protein adsorption and release. It is worth pointing out that the kinetic release of growth factors, up to 28 days, and their biological activity maintenance seem to be compatible with intervertebral disc regenerative medicine.
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http://dx.doi.org/10.1039/c7tb00332cDOI Listing
April 2017

Criteria to define a more relevant reference sample of titanium dioxide in the context of food: a multiscale approach.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2017 May 14;34(5):653-665. Epub 2017 Feb 14.

a UR1268 BIA (Biopolymères Interactions Assemblages) , INRA , Nantes , France.

Titanium dioxide (TiO) is a transition metal oxide widely used as a white pigment in various applications, including food. Due to the classification of TiO nanoparticles by the International Agency for Research on Cancer as potentially harmful for humans by inhalation, the presence of nanoparticles in food products needed to be confirmed by a set of independent studies. Seven samples of food-grade TiO (E171) were extensively characterised for their size distribution, crystallinity and surface properties by the currently recommended methods. All investigated E171 samples contained a fraction of nanoparticles, however, below the threshold defining the labelling of nanomaterial. On the basis of these results and a statistical analysis, E171 food-grade TiO totally differs from the reference material P25, confirming the few published data on this kind of particle. Therefore, the reference material P25 does not appear to be the most suitable model to study the fate of food-grade TiO in the gastrointestinal tract. The criteria currently to obtain a representative food-grade sample of TiO are the following: (1) crystalline-phase anatase, (2) a powder with an isoelectric point very close to 4.1, (3) a fraction of nanoparticles comprised between 15% and 45%, and (4) a low specific surface area around 10 m g.
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http://dx.doi.org/10.1080/19440049.2017.1284346DOI Listing
May 2017

Modulation of Defects in Semiconductors by Facile and Controllable Reduction: The Case of p-type CuCrO2 Nanoparticles.

Inorg Chem 2016 Aug 13;55(15):7729-33. Epub 2016 Jul 13.

Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS , 2 rue de la Houssinière, BP 32229, 44322 Nantes, Cedex 03, France.

Optical and electrical characteristics of solid materials are well-known to be intimately related to the presence of intrinsic or extrinsic defects. Hence, the control of defects in semiconductors is of great importance to achieve specific properties, for example, transparency and conductivity. Herein, a facile and controllable reduction method for modulating the defects is proposed and used for the case of p-type delafossite CuCrO2 nanoparticles. The optical absorption in the infrared region of the CuCrO2 material can then be fine-tuned via the continuous reduction of nonstoichiometric Cu(II), naturally stabilized in small amounts. This reduction modifies the concentration of positive charge carriers in the material, and thus the conductive and reflective properties, as well as the flat band potential. Indeed, this controllable reduction methodology provides a novel strategy to modulate the (opto-) electronic characteristics of semiconductors.
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http://dx.doi.org/10.1021/acs.inorgchem.6b01169DOI Listing
August 2016

Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions.

Small 2016 Jun 7;12(21):2885-92. Epub 2016 Apr 7.

Department of Materials- and Geosciences, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287, Darmstadt, Germany.

Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.
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http://dx.doi.org/10.1002/smll.201600396DOI Listing
June 2016

Creating nanoporosity in silver nanocolumns by direct exposure to radio-frequency air plasma.

Nanoscale 2016 Jan;8(1):141-8

Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 Rue de la Houssinière B.P. 32229, 44322 Nantes cedex 3, France.

Nanoporous materials are of great importance for a broad range of applications including catalysis, optical sensors and water filtration. Although several approaches already exist for the creation of nanoporous materials, the race for the development of versatile methods, more suitable for the nanoelectronics industry, is still ongoing. In this communication we report for the first time on the possibility of generating nanoporosity in silver nanocolumns using a dry approach based on the oxidation of silver by direct exposure to a commercially available radio-frequency air plasma. The silver nanocolumns are created by glancing angle deposition using magnetron sputtering of a silver target in pure argon plasma. We show that upon exposure to the rf air plasma, the nanocolumns transform from solid silver into nanoporous silver oxide. We further show that by tuning the plasma pressure and the exposure duration, the oxidation process can be finely adjusted allowing for precisely controlling the morphology and the nanoporosity of the silver oxide nanocolumns. The generation of porosity within the silver nanocolumns is explained according to a cracking-induced oxidation mechanism based on two repeated events occurring alternately during the oxidation process: (i) oxidation of silver upon exposure to the air plasma and (ii) generation of nanocracks and blisters within the oxide layer due to the high internal stress generated within the material during oxidation.
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http://dx.doi.org/10.1039/c5nr07145cDOI Listing
January 2016

Unravelling the origin of the giant Zn deficiency in wurtzite type ZnO nanoparticles.

Sci Rep 2015 Sep 3;5:12914. Epub 2015 Sep 3.

Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, 44322 Nantes cedex 3, France.

Owing to its high technological importance for optoelectronics, zinc oxide received much attention. In particular, the role of defects on its physical properties has been extensively studied as well as their thermodynamical stability. In particular, a large concentration of Zn vacancies in ZnO bulk materials is so far considered highly unstable. Here we report that the thermal decomposition of zinc peroxide produces wurtzite-type ZnO nanoparticles with an extraordinary large amount of zinc vacancies (>15%). These Zn vacancies segregate at the surface of the nanoparticles, as confirmed by ab initio calculations, to form a pseudo core-shell structure made of a dense ZnO sphere coated by a Zn free oxo-hydroxide mono layer. In others terms, oxygen terminated surfaces are privileged over zinc-terminated surfaces for passivation reasons what accounts for the Zn off-stoichiometry observed in ultra-fine powdered samples. Such Zn-deficient Zn1-xO nanoparticles exhibit an unprecedented photoluminescence signature suggesting that the core-shell-like edifice drastically influences the electronic structure of ZnO. This nanostructuration could be at the origin of the recent stabilisation of p-type charge carriers in nitrogen-doped ZnO nanoparticles.
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http://dx.doi.org/10.1038/srep12914DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558607PMC
September 2015

Unusual dealloying effect in gold/copper alloy thin films: the role of defects and column boundaries in the formation of nanoporous gold.

ACS Appl Mater Interfaces 2015 Feb 20;7(4):2310-21. Epub 2015 Jan 20.

Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS , 2 rue de la Houssinière, B.P. 32229, 44322 Nantes cedex 3, France.

Understanding the dealloying mechanisms of gold-based alloy thin films resulting in the formation of nanoporous gold with a sponge-like structure is essential for the future design and integration of this novel class of material in practical devices. Here we report on the synthesis of nanoporous gold thin films using a free-corrosion approach in nitric acid applied to cosputtered Au-Cu thin films. A relationship is established between the as-grown Au-Cu film characteristics (i.e., composition, morphology, and structure) and the porosity of the sponge-like gold thin films. We further demonstrate that the dealloying approach can be applied to nonhomogenous Au-Cu alloy thin films consisting of periodic and alternate Au-rich/Au-poor nanolayers. In such a case, however, the dealloying process is found to be altered and unusual etching stages arise. Thanks to defects and column boundaries playing the role of channels, the nitric acid is found to quickly penetrate within the films and then laterally (i.e., parallel to the film surface) attacks the nanolayers rather than perpendicularly. As a consequence to this anisotropic etching, the Au-poor layers are etched preferentially and transform into Au pillars holding the Au-rich layers and preventing them against collapsing. A further exposure to nitric acid results in the collapsing of the Au-rich layers accompanied by a transition from a multilayered to a sponge-like structure. A scenario, supported by experimental observations, is further proposed to provide a detailed explanation of the fundamental mechanisms occurring during the dealloying process of films with a multilayered structure.
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http://dx.doi.org/10.1021/am5065816DOI Listing
February 2015

Fluorescent carboxylic and phosphonic acids: comparative photophysics from solution to organic nanoparticles.

Phys Chem Chem Phys 2013 Aug;15(30):12748-56

Université de Nantes, CEISAM-UMR CNRS 6230, Nantes, France.

Phosphonic and carboxylic fluorescent nanoparticles have been fabricated by direct reprecipitation in water. Their fluorescence properties strongly differ from those of the corresponding esters where strong H-bonding formation is prohibited. Comparative experiments between the two acid derivatives, differing only in their acid functions while keeping the same alkyl chain, have evidenced the peculiar behavior of the phosphonic acid derivative compared to its carboxylic analog. A dramatic emission quenching for the phosphonic acid in aprotic toluene could be observed while a fivefold increase in the fluorescence signal was observed for molecules assembled as nanoparticles. Such properties have been attributed on the theoretical basis to the formation of folded conformers in solution, leading to deactivation of the radiative excited state through intramolecular H-bonding. These studies evidence for the first time through time-resolved fluorescence measurements the stronger H-donating character of phosphonic acids compared to the carboxylic ones, and provide information on the degree of structural heterogeneity within the nanoparticles. They should pave the way for the rational fabrication of chelating acid fluorophores, able to complex metal oxides to yield stiff hybrid magnetofluorescent nanoparticles which are attracting considerable attention in the growing fields of bimodal imaging and vectorization applications.
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http://dx.doi.org/10.1039/c3cp51369fDOI Listing
August 2013

Color control in coaxial two-luminophore nanowires.

ACS Nano 2013 Apr 18;7(4):2977-87. Epub 2013 Mar 18.

Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, France.

We report a general and simple approach to take control of the color of light-emitting two-luminophore hybrid nanowires (NWs). Our strategy is based on the spatial control at the nanoscale (coaxial geometry) and the spectral selection of the two kinds of luminophores in order to restrict complex charge and energy transfers. Thus, it is possible to control the color of the photoluminescence (PL) as an interpolation of the CIE (Commission Internationale de l'Eclairage) coordinates of each luminophore. For this purpose, we selected a green-emitting semiconducting polymer and a red-emitting hexanuclear metal cluster compound, (n-Bu4N)2Mo6Br8F6, dispersed in a poly(methyl-methacrylate) (PMMA) matrix. The great potential and the versatility of this strategy have been demonstrated for two configurations. First, a yellow PL with a continuous change along the nanowire has been evidenced when the proportion of the PPV shell versus the nanocomposite core, that is, the green/red volumic ratio, progressively shifts from 1:2 to 1:5. Second, an extremely abrupt change in the PL color with red-green-yellow segments has been achieved. A simple model corroborates the effectiveness of this strategy. PL excitation and time-resolved experiments also confirm that no significant charge and energy transfers are involved. The two-luminophore hybrid nanowires may find widespread nanophotonic applications in multicolor emitting sources, lasers and chemical and biological sensors.
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http://dx.doi.org/10.1021/nn400763rDOI Listing
April 2013

Highly ordered ultralong magnetic nanowires wrapped in stacked graphene layers.

Beilstein J Nanotechnol 2012 11;3:846-51. Epub 2012 Dec 11.

Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3, France, Telephone: +33 (0) 240 376 434.

We report on the synthesis and magnetic characterization of ultralong (1 cm) arrays of highly ordered coaxial nanowires with nickel cores and graphene stacking shells (also known as metal-filled carbon nanotubes). Carbon-containing nickel nanowires are first grown on a nanograted surface by magnetron sputtering. Then, a post-annealing treatment favors the metal-catalyzed crystallization of carbon into stacked graphene layers rolled around the nickel cores. The observed uniaxial magnetic anisotropy field oriented along the nanowire axis is an indication that the shape anisotropy dominates the dipolar coupling between the wires. We further show that the thermal treatment induces a decrease in the coercivity of the nanowire arrays. This reflects an enhancement of the quality of the nickel nanowires after annealing attributed to a decrease of the roughness of the nickel surface and to a reduction of the defect density. This new type of graphene-ferromagnetic-metal nanowire appears to be an interesting building block for spintronic applications.
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http://dx.doi.org/10.3762/bjnano.3.95DOI Listing
February 2013

Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel.

Beilstein J Nanotechnol 2012 2;3:360-7. Epub 2012 May 2.

Dipartimento di Fisica, Università di Roma Tor Vergata, 00133 Roma, Italy.

We have taken advantage of the native surface roughness and the iron content of AISI-316 stainless steel to grow multiwalled carbon nanotubes (MWCNTs) by chemical vapour deposition without the addition of an external catalyst. The structural and electronic properties of the synthesized carbon nanostructures have been investigated by a range of electron microscopy and spectroscopy techniques. The results show the good quality and the high graphitization degree of the synthesized MWCNTs. Through energy-loss spectroscopy we found that the electronic properties of these nanostructures are markedly different from those of highly oriented pyrolytic graphite (HOPG). Notably, a broadening of the π-plasmon peak in the case of MWCNTs is evident. In addition, a photocurrent was measured when MWCNTs were airbrushed onto a silicon substrate. External quantum efficiency (EQE) and photocurrent values were reported both in planar and in top-down geometry of the device. Marked differences in the line shapes and intensities were found for the two configurations, suggesting that two different mechanisms of photocurrent generation and charge collection are in operation. From this comparison, we are able to conclude that the silicon substrate plays an important role in the production of electron-hole pairs.
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http://dx.doi.org/10.3762/bjnano.3.42DOI Listing
September 2012

The 2C putative helicase of echovirus 30 adopts a hexameric ring-shaped structure.

Acta Crystallogr D Biol Crystallogr 2010 Oct 18;66(Pt 10):1116-20. Epub 2010 Sep 18.

Architecture et Fonction des Macromolécules Biologiques, UMR 6098 Centre National de la Recherche Scientifique, Université de la Méditerranée and Université de Provence, Case 925, 163 Avenue de Luminy, 13288 Marseille CEDEX 9, France.

The 2C protein, which is an essential ATPase and one of the most conserved proteins across the Picornaviridae family, is an emerging antiviral target for which structural and functional characterization remain elusive. Based on a distant relationship to helicases of small DNA viruses, piconavirus 2C proteins have been predicted to unwind double-stranded RNAs. Here, a terminally extended variant of the 2C protein from echovirus 30 has been studied by means of enzymatic activity assays, transmission electron microscopy, atomic force microscopy and dynamic light scattering. The transmission electron-microscopy technique showed the existence of ring-shaped particles with ∼12 nm external diameter. Image analysis revealed that these particles were hexameric and resembled those formed by superfamily 3 DNA virus helicases.
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http://dx.doi.org/10.1107/S090744491002809XDOI Listing
October 2010

Structure and white luminescence of Eu-activated (Ba,Sr)(13-x)Al(22-2x)Si(10+2x)O66 materials.

Inorg Chem 2008 May 4;47(10):4226-35. Epub 2008 Apr 4.

Institut des Matériaux Jean Rouxel (IMN), UMR 6502 CNRS-Université de Nantes, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3, France.

The optical properties of Eu-activated (Ba,Sr)(13-x)Al(22-2x)Si(10+2x)O66 materials have been determined after the structural reinvestigation of the hypothetical Ba 13Al 22Si 10O 66 material on the basis of the Gebert's model. The white fluorescence and phosphorescence of the (Ba,Sr)(13-x)Al(22-2x)Si(10+2x)O66:Eu series result from the existence of two broad emission bands associated with (8)H-4f(6)5d(1)-->(8)S-4f(7) transitions peaking at 534 and 438 nm, the intensities of which may be tuned at room temperature via the control of the europium concentration and the substitution of Sr for Ba. This suggests the possibility to adjust the emission of the material to white LED requisites.
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http://dx.doi.org/10.1021/ic702240qDOI Listing
May 2008
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