Publications by authors named "Hervé Martinez"

21 Publications

  • Page 1 of 1

Optimization of elemental selenium (Se(0)) determination in yeasts by anion-exchange HPLC-ICP-MS.

Anal Bioanal Chem 2021 Mar 1;413(7):1809-1816. Epub 2021 Feb 1.

UT2A, Hélioparc Pau-Pyrénées, 2 avenue du président Angot, 64000, Pau, France.

An analytical method was developed for the speciation of elemental selenium (Se(0)) in selenized yeasts by anion-exchange HPLC-ICP-MS after its chemical transformation into SeSO by reaction with sodium sulfite. The presence of Se(0) in the yeasts was further confirmed by single-particle ICP-MS. Indeed, Se nanoparticles, if present, are expected to be, at least partly, Se(0). X-ray photoelectron spectroscopy, a well-recognized technique for chemical element speciation in the solid state, was also used with this objective. Both methods were able to confirm the presence of Se(0) in the selenized yeasts but failed to provide reliable quantitative results. Analytical performances of the HPLC-ICP-MS method were then evaluated for Se(0) determination. Quantification limits of 1 mg/kg were reached. The recovery levels from an added quantity comprised between 93 and 101%. Within-run and between-run precisions were both below 8%. The procedure developed was finally applied to quantify Se(0) content in a series of seven yeast batches from different suppliers. Se(0) was found to be present in all the studied yeasts and represented on average 10-15% of the total Se.
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http://dx.doi.org/10.1007/s00216-020-03129-yDOI Listing
March 2021

A nanopatterned dual reactive surface driven by block copolymer self-assembly.

Nanoscale 2020 Apr 27;12(14):7532-7537. Epub 2020 Mar 27.

Universite de Pau et Pays de l'Adour, E2S UPPA, CNRS, Institut des Sciences Analytiques & de Physico-Chimie pour l'Environnement & les Matériaux, UMR5254, 64000, Pau, France.

Herein, we report the selective functionalization of nano-domains obtained by the self-assembly of a polystyrene-block-poly(vinyl benzyl azide) PS-b-PVBN copolymer synthesized in three steps. First, a polystyrene macro-initiator was synthesized, and then extended with vinyl benzyl chloride by nitroxide mediated polymerization to form polystyrene-block-poly(vinyl benzyl chloride) PS-b-PVBC. Nucleophilic substitution of vinyl benzyl chloride into a vinyl benzyl azide moiety is finally performed to obtain PS-b-PVBN which self-assembled into nano-domains of vinyl benzyl azide PVBN. Click chemistry was then used to bind functional gold nanoparticles and poly(N-isopropylacrylamide) (PNIPAM) on PVBN domains due to the specific anchoring at the surface of the nanopatterned film. Atomic force microscopy (AFM) was used to observe the block copolymer self-assembly and the alignment of the gold nanoparticles at the surface of the PVBN nanodomains. Thorough X-ray photoelectron spectroscopy (XPS) analysis of the functional film showed evidence of the sequential grafting of nanoparticles and PNIPAM. The hybrid surface expresses thermo-responsive properties and serves as a pattern to perfectly align and control the assembly of inorganic particles at the nanoscale.
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http://dx.doi.org/10.1039/c9nr10740aDOI Listing
April 2020

Sustainable quantum dot chemistry: effects of precursor, solvent, and surface chemistry on the synthesis of ZnP nanocrystals.

Chem Commun (Camb) 2020 Mar;56(22):3321-3324

LPCNO, Université de Toulouse, CNRS, INSA, UPS, 135 Avenue de Rangueil, 31077 Toulouse, France.

The quest of exploring alternative materials for the replacement of toxic cadmium- and lead-based quantum dots (QDs) is necessary for envisaging a sustainable future but remains highly challenging. Tackling this issue, we present the synthesis of Zn3P2 nanocrystals (NCs) of unprecedented quality. New, reactive zinc precursors yield highly crystalline, colloidally stable particles, exhibiting oxide-free surfaces, size tunability and outstanding optical properties relative to previous reports of zinc phosphide QDs.
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http://dx.doi.org/10.1039/c9cc09368kDOI Listing
March 2020

[email protected] Functional Nanoparticle-Driven Rod-Coil Diblock Copolymer Self-Assembly.

Langmuir 2019 Dec 10;35(51):16925-16934. Epub 2019 Dec 10.

CNRS/Université de Pau et des Pays de l'Adour/E2S UPPA , IPREM CNRS-UMR 5254 Hélioparc , 2 Avenue Président Angot , 64053 Pau Cedex 9, France.

Herein, a novel strategy to overcome the influence of π-π stacking on the rod-coil copolymer organization is reported. A diblock copolymer poly(3-hexylthiophene)--poly(ethylene glycol methyl ether methacrylate) (P3HT--PEGMA) was synthesized by the Huisgen cycloaddition, so-called "click chemistry", combining the PEGMA and P3HT blocks synthesized by atom transfer radical polymerization and Kumada catalyst transfer polymerization, respectively. Using a dip-coating process, we controlled the original film organization of the diblock copolymer by the crystallization of the P3HT block via π-π stacking. The morphology of the P3HT--PEGMA films was influenced by the incorporation of gold nanoparticles (GNPs) coated by poly(ethylene glycol) ligands. Indeed, the crystalline structuration of the P3HT sequence was counterbalanced by the addition in the film of gold nanoparticles finely localized within the copolymer PEGMA matrix. Transmission electron microscopy and time-of-flight secondary ion mass spectrometry analysis validated the GNP homogeneous localization into the compatible PEGMA phase. Differential scanning calorimetry showed the rod block crystallization disruption. A morphological transition of the self-assembly is observed by atomic force microscopy from P3HT fibrils into out-of-plane cylinders driven by the nanophase segregation.
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http://dx.doi.org/10.1021/acs.langmuir.9b02744DOI Listing
December 2019

Paving the Way for K-Ion Batteries: Role of Electrolyte Reactivity through the Example of Sb-Based Electrodes.

ACS Appl Mater Interfaces 2018 Oct 28;10(40):34116-34122. Epub 2018 Sep 28.

CNRS/UNIV Pau & Pays Adour/E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, UMR5254 , 64000 Pau , France.

Developing potassium-ion batteries remains a challenge so far due to the lack of efficient electrolytes. Moreover, the high reactivity of K metal and the use of half-cells may greatly alter both the electrochemical performance and the solid electrolyte interphase formation. Here, it is shown that in K metal/Sb half-cells, Coulombic efficiency improvement is achieved by the addition of fluoroethylene carbonate + vinylene carbonate to propylene carbonate (PC), the replacement of PC by ethylene carbonate/diethyl carbonate, and the replacement of KPF by potassium bis(fluorosulfonyl)imide. Surprisingly, however, storage of cells containing K metal leads to the coloration of K metal, separators, and Sb electrodes, whereas no change occurs for cells prepared without K metal. These results demonstrate that for all electrolytes, the high electrolyte reactivity with K metal also influences the Sb/electrolyte interface via a cross-talk mechanism. This observation is supported by gas chromatography/mass spectrometry analysis of electrolytes and X-ray photoelectron spectroscopy analysis of Sb electrodes. In summary, these results indicate that the search for efficient electrolytes for potassium-ion batteries must be carried out in full cells if one wants to obtain meaningful correlations between electrochemical performance and electrode/electrolyte interfacial properties. Overall, the results presented here are also likely to benefit the development of other emerging Na- and Mg-ion cell chemistries.
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http://dx.doi.org/10.1021/acsami.8b08902DOI Listing
October 2018

Cu-doping of calcium phosphate bioceramics: From mechanism to the control of cytotoxicity.

Acta Biomater 2018 Jan 21;65:462-474. Epub 2017 Oct 21.

Université Clermont Auvergne, CNRS, SIGMA Clermont, ICCF, F-63000 Clermont-Ferrand, France. Electronic address:

In this study, the Cu-doping mechanism of Biphasic Calcium Phosphate (BCP) was thoroughly investigated, as was its ionic release behavior, in order to elucidate cytotoxicity features of these bioceramics. BCP are composed of hydroxyapatite (Ca(PO)(OH)) and β-TCP (Ca(PO)). The two phases present two different doping mechanisms. Incorporation into the β-TCP structure is achieved at around 700 °C thanks to a substitution mechanism leading to the Cu-doped CaCu(PO) compound. Incorporation into the HAp structure is achieved thanks to an interstitial mechanism that is limited to a Cu-poor HAp phase for temperatures below 1100 °C (CaCu(PO)(OH)O with x < 0.1). Above 1100 °C, the same interstitial mechanism leads to the formation of a Cu-rich HAp mixed-valence phase (CaCuCu(PO)(OH)O with x + y ∼ 0.5). The formation of both high-temperature Cu-doped α-TCP and Cu(PO) phases above 1100 °C induces a transformation into the Cu-rich HAp phase on cooling. The linear OCuO oxocuprate entity was confirmed by EXAFS spectroscopy, and the mixed Cu/Cu valence was evidenced by XPS analyses. Ionic releases (Cu/Cu, Ca, PO and OH) in water and in simulated body media were investigated on as-synthesized ceramics to establish a pretreatment before biological applications. Finally the cytotoxicity of pretreated disks was evaluated, and results confirm that Cu-doped BCP samples are promising bioceramics for bone substitutes and/or prosthesis coatings.

Statement Of Significance: Biphasic Calcium Phosphates (BCP) are bioceramics composed of hydroxyapatite (HAp, Ca(PO)(OH)) and beta-Tricalium Phosphate (β-TCP, Ca(PO)). Because their chemical and mineral composition closely resembles that of the mineral component of bone, they are potentially interesting candidates for bone repair surgery. Doping can advantageously be used to improve their biological behaviors; however, it is important to describe the doping mechanism of BCP thoroughly in order to fully appraise the benefit of the doping process. The present paper scrutinizes in detail the incorporation of copper cation in order to correctly interpret the behavior of the Cu-doped bioceramic in biological fluid. The understanding of the copper doping mechanism, related to doping mechanism of others 3d-metal cations, makes it possible to explain the rates and kinetic of release of the dopant in biological medium. Finally, the knowledge of the behavior of the copper doped ceramic in biological environment allowed the tuning of its cytotoxicity properties. The present study resulted on pre-treated ceramic disks which have been evaluated as promising biocompatible ceramic for bone substitute and/or prosthesis coating: good adherence of bone marrow cells with good cell viability.
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http://dx.doi.org/10.1016/j.actbio.2017.10.028DOI Listing
January 2018

Hexakis [60]Fullerene Adduct-Mediated Covalent Assembly of Ruthenium Nanoparticles and Their Catalytic Properties.

Chemistry 2017 Sep 29;23(54):13379-13386. Epub 2017 Aug 29.

CNRS, LCC (Laboratoire de Chimie de Coordination), Composante ENSIACET, 4 allée Emile Monso, BP 44099, 31030, Toulouse Cedex 4, France.

The C (COOH) hexa-adduct has been successfully used as a building block to construct carboxylate bridged 3D networks with very homogeneous sub-1.8 nm ruthenium nanoparticles. The obtained nanostructures are active in nitrobenzene selective hydrogenation.
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http://dx.doi.org/10.1002/chem.201701043DOI Listing
September 2017

Effect of the Functionalization Process on the Colloidal, Magnetic Resonance Imaging, and Bioelimination Properties of Mono- or Bisphosphonate-Anchored Dendronized Iron Oxide Nanoparticles.

Chempluschem 2017 Apr;82(4):647-659

Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, CNRS, Université de Strasbourg, 23, rue du Loess, BP 43, 67034, Strasbourg Cedex 2, France.

The functionalization process of iron oxide nanoparticles (NPs) is a major step and has to ensure a small particle size distribution (below 100 nm) and to preserve good magnetic properties suitable for in vivo applications. Two functionalization processes are here compared to coat iron oxide NPs, synthesized by thermal decomposition, with dendron molecules bearing either a mono- or a bisphosphonate anchoring group. The two processes are direct ligand exchange and the simultaneous ligand exchange and phase transfer process. The latter process led to a larger size distribution than the former. The phosphonate group is confirmed to be a strong anchoring agent from X-ray photoelectron spectroscopy (XPS) and IR characterizations whatever the grafting process and the number of phosphonate groups, it also confirms the preservation of the NPs' magnetic properties. All dendronized NPs display good in vitro MRI properties and those obtained by direct exchange showed no cell internalization, an efficient in vivo MRI contrast enhancement, and elimination by both urinary and hepato-biliary ways.
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http://dx.doi.org/10.1002/cplu.201700049DOI Listing
April 2017

Dual Cation- and Anion-Based Redox Process in Lithium Titanium Oxysulfide Thin Film Cathodes for All-Solid-State Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2017 Jan 6;9(3):2275-2284. Epub 2017 Jan 6.

CEA LETI , Minatec Campus, 17 rue des Martyrs, F-38054 Grenoble, France.

A dual redox process involving Ti/Ti cation species and S/(S) anion species is highlighted in oxygenated lithium titanium sulfide thin film electrodes during lithium (de)insertion, leading to a high specific capacity. These cathodes for all-solid-state lithium-ion microbatteries are synthesized by sputtering of LiTiS targets prepared by different means. The limited oxygenation of the films that is induced during the sputtering process favors the occurrence of the S/(S) redox process at the expense of the Ti/Ti one during the battery operation, and influences its voltage profile. Finally, a perfect reversibility of both electrochemical processes is observed, whatever the initial film composition. All-solid-state lithium microbatteries using these amorphous lithiated titanium disulfide thin films and operated between 1.5 and 3.0 V/Li/Li deliver a greater capacity (210-270 mAh g) than LiCoO, with a perfect capacity retention (-0.0015% cycle).
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http://dx.doi.org/10.1021/acsami.6b11987DOI Listing
January 2017

Design and Cellular Fate of Bioinspired Au-Ag [email protected] Silica Nanoparticles.

Langmuir 2016 10 21;32(39):10073-10082. Epub 2016 Sep 21.

Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux (IPREM)-UMR CNRS/UPPA 5254, Equipe de Chimie Physique (ECP), Université de Pau et des Pays de l'Adour (UPPA), Technopôle Hélioparc Pau Pyrénées , 2, Avenue du Président Pierre Angot, 64053 Pau Cedex 09, France.

Silica-coated gold-silver alloy nanoshells were obtained via a bioinspired approach using gelatin and poly-l-lysine (PLL) as biotemplates for the interfacial condensation of sodium silicate solutions. X-ray photoelectron spectroscopy was used as an efficient tool for the in-depth and complete characterization of the chemical features of nanoparticles during the whole synthetic process. Cytotoxicity assays using HaCaT cells evidenced the detrimental effect of the gelatin nanocoating and significant induction of late apoptosis after silicification. In contrast, PLL-modified nanoparticles had less biological impact that was further improved by the silica layer, and uptake rates of up to 50% of those of the initial particles could be achieved. These results are discussed considering the effect of nanosurface confinement of the biopolymers on their chemical and biological reactivity.
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http://dx.doi.org/10.1021/acs.langmuir.6b02810DOI Listing
October 2016

Air- and water-resistant noble metal coated ferromagnetic cobalt nanorods.

ACS Nano 2015 Mar 9;9(3):2792-804. Epub 2015 Mar 9.

†Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse; INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France.

Cobalt nanorods possess ideal magnetic properties for applications requiring magnetically hard nanoparticles. However, their exploitation is undermined by their sensitivity toward oxygen and water, which deteriorates their magnetic properties. The development of a continuous metal shell inert to oxidation could render them stable, opening perspectives not only for already identified applications but also for uses in which contact with air and/or aqueous media is inevitable. However, the direct growth of a conformal noble metal shell on magnetic metals is a challenge. Here, we show that prior treatment of Co nanorods with a tin coordination compound is the crucial step that enables the subsequent growth of a continuous noble metal shell on their surface, rendering them air- and water-resistant, while conserving the monocrystallity, metallicity and the magnetic properties of the Co core. Thus, the as-synthesized core-shell ferromagnetic nanorods combine high magnetization and strong uniaxial magnetic anisotropy, even after exposure to air and water, and hold promise for successful implementation in in vitro biodiagnostics requiring probes of high magnetization and anisotropic shape.
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http://dx.doi.org/10.1021/nn506709kDOI Listing
March 2015

Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte.

Nanoscale Res Lett 2014 2;9(1):544. Epub 2014 Oct 2.

Aix-Marseille Université, CNRS, LP3 UMR 7341, F-13288, Marseille Cedex 9, France ; Aix-Marseille Université, CNRS, MADIREL UMR 7246, F-13397, Marseille Cedex 20, France.

This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance ((1)H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte.
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http://dx.doi.org/10.1186/1556-276X-9-544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4194452PMC
October 2014

Effect of the nanoparticle synthesis method on dendronized iron oxides as MRI contrast agents.

Dalton Trans 2013 Feb;42(6):2146-57

Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, CNRS, Université de Strasbourg, 23, rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France.

Aqueous suspensions of dendronized iron oxide nanoparticles (NPs) have been obtained after functionalization, with two types of dendrons, of NPs synthesized either by coprecipitation (leading to naked NPs in water) or by thermal decomposition (NPs in situ coated by oleic acid in an organic solvent). Different grafting strategies have been optimized depending on the NPs synthetic method. The size distribution, the colloidal stability in isoosmolar media, the surface complex nature as well as the preliminary biokinetic studies performed with optical imaging, and the contrast enhancement properties evaluated through in vitro and in vivo MRI experiments, have been compared as a function of the nature of both dendrons and NPs. All functionalized NPs displayed good colloidal stability in water, however the ones bearing a peripheral carboxylic acid function gave the best results in isoosmolar media. Whereas the grafting rates were similar, the nature of the surface complex depended on the NPs synthetic method. The in vitro contrast enhancement properties were better than commercial products, with a better performance of the NPs synthesized by coprecipitation. On the other hand, the NPs synthesized by thermal decomposition were more efficient in vivo. Furthermore, they both displayed good biodistribution with renal and hepatobiliary elimination pathways and no consistent RES uptake.
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http://dx.doi.org/10.1039/c2dt31788eDOI Listing
February 2013

InP/ZnS nanocrystals: coupling NMR and XPS for fine surface and interface description.

J Am Chem Soc 2012 Dec 20;134(48):19701-8. Epub 2012 Nov 20.

Université de Toulouse; INSA, UPS, CNRS; LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse, France.

Advanced (1)H, (13)C, and (31)P solution- and solid-state NMR studies combined with XPS were used to probe, at the molecular scale, the composition (of the core, the shell, and the interface) and the surface chemistry of InP/ZnS core/shell quantum dots prepared via a non-coordinating solvent strategy. The interface between the mismatched InP and ZnS phases is composed of an amorphous mixed oxide phase incorporating InPO(x) (with x = 3 and predominantly 4), In(2)O(3), and InO(y)(OH)(3-2y) (y = 0, 1). Thanks to the analysis of the underlying reaction mechanisms, we demonstrate that the oxidation of the upper part of the InP core is the consequence of oxidative conditions brought by decarboxylative coupling reactions (ketonization). These reactions occur during both the core preparation and the coating process, but according to different mechanisms.
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http://dx.doi.org/10.1021/ja307124mDOI Listing
December 2012

Electrochemical fabrication and properties of highly ordered Fe-doped TiO2 nanotubes.

Chemphyschem 2012 Nov 28;13(16):3707-13. Epub 2012 Aug 28.

Aix Marseille University, CNRS, LP UMR, Marseille, France.

Highly-ordered Fe-doped TiO(2) nanotubes (TiO(2)nts) were fabricated by anodization of co-sputtered Ti-Fe thin films in a glycerol electrolyte containing NH(4)F. The as-sputtered Ti-Fe thin films correspond to a solid solution of Ti and Fe according to X-ray diffraction. The Fe-doped TiO(2)nts were studied in terms of composition, morphology and structure. The characterization included scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Mott-Schottky analysis. As a result of the Fe doping, an indirect bandgap of 3.0 eV was estimated using Tauc's plot, and this substantial red-shift extends its photoresponse to visible light. From the Mott-Schottky analysis, the flat-band potential (E(fb)) and the charge carrier concentration (N(D)) were determined to be -0.95 V vs Ag/AgCl and 5.0×10(19) cm(-3) respectively for the Fe-doped TiO(2)nts, whilst for the undoped TiO(2)nts, E(fb) of -0.85 V vs Ag/AgCl and N(D) of 6.5×10(19) cm(-3) were obtained.
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http://dx.doi.org/10.1002/cphc.201200406DOI Listing
November 2012

Highly conformal electrodeposition of copolymer electrolytes into titania nanotubes for 3D Li-ion batteries.

Nanoscale Res Lett 2012 Jun 27;7(1):349. Epub 2012 Jun 27.

Aix Marseille Université, CNRS, Chemistry of Materials Research Group LP3 UMR 7341, Marseille, F-13288, France.

The highly conformal electrodeposition of a copolymer electrolyte (PMMA-PEO) into self-organized titania nanotubes (TiO2nt) is reported. The morphological analysis carried out by scanning electron microscopy and transmission electron microscopy evidenced the formation of a 3D nanostructure consisting of a copolymer-embedded TiO2nt. The thickness of the copolymer layer can be accurately controlled by monitoring the electropolymerization parameters. X-ray photoelectron spectroscopy measurements confirmed that bis(trifluoromethanesulfone)imide salt was successfully incorporated into the copolymer electrolyte during the deposition process. These results are crucial to fabricate a 3D Li-ion power source at the micrometer scale using TiO2nt as the negative electrode.
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http://dx.doi.org/10.1186/1556-276X-7-349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3536562PMC
June 2012

Intercalation and grafting of benzene derivatives into zinc-aluminum and copper-chromium layered double hydroxide hosts: an XPS monitoring study.

Phys Chem Chem Phys 2011 Oct 5;13(39):17564-78. Epub 2011 Sep 5.

IPREM-UMR CNRS 5254, Université de Pau et des Pays de l'Adour, Pau, France.

We report an original strategy to describe, via X-ray photoelectron spectroscopy (XPS) measurements, the interactions between the organic and the mineral sub-systems within a multifunctional hybrid material. A tunable layered double hydroxide (LDH) host system, either a Zn(2)Al- or Cu(2)Cr-hydrotalcite like compound, is modified with the insertion of the organic guest entities, 4-phenol-sulfonate (HBS) or -carboxylate (HBC). The resulting interactions are studied at two levels: after the organic molecules' insertion in the host LDH (ionic exchange between the LDH counter-ions and the organic anions) and after the condensation (grafting) of the organic species onto the mineral layers when thermally treated. For the inserted material, the main XPS results show a stabilization of the organic molecules within the mineral sheets via H bonding as found elsewhere with FTIR study, the mineral matrix being unchanged. The XPS signal of the organic molecules slightly changes with a widening of core peaks, attesting to some local surrounding modifications. When heating up the Zn(2)Al hybrid material, stronger interactions between organic and inorganic systems appeared from around 80 °C with some obvious electronic changes as monitored with the XPS S2p signal of the HBS guest molecules. At the same time, the PXRD pattern clearly shows a decrease of the basal spacing according to a two step contraction process which could be interpreted as a progressive organic molecule condensation onto the inorganic layers via iono-covalent bonds. A copper-chromium LDH is also studied to probe the same kind of interactions with the HBS molecules. The ability of distortion of such mineral material involves a peculiar process of contraction from 40 °C with the immediate and effective anchorage of organic molecules.
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http://dx.doi.org/10.1039/c1cp20453jDOI Listing
October 2011

Investigation of glow-discharge-induced morphology modifications on silicon wafers and chromium conversion coatings by AFM and rugosimetry.

Anal Bioanal Chem 2010 Apr 22;396(8):2841-53. Epub 2009 Dec 22.

IPREM-LCABIE (UMR CNRS 5254), Université de Pau et des Pays de l'Adour, 2 Av. Président Angot, 64053 Pau, France.

The effect of radiofrequency glow-discharge sputtering on the sample surface in terms of modifications in the surface morphology were investigated in this work by using atomic force microscopy (AFM) and rugosimetry measurements. The influence of GD operating parameters (e.g. rf power, discharge pressure and sputtering time) on surface roughening was investigated using two different types of samples: mirror-polished and homogeneous silicon wafers and chromate conversion coatings (CCCs). Surface morphology changes produced by GD sputtering into the sample surface were carefully investigated by AFM and rugosimetry, both at the original sample surface and at the bottom of GD craters using different GD experimental conditions, such as the sputtering time (from 1 s to 20 min), rf forward power (20-60 W for the Si wafer and 10-60 W for the CCC), and discharge pressure (400-1,000 Pa for the Si wafer and 500-1000 Pa for the CCC). In the present study, GD-induced morphology modifications were observed after rf-GD-OES analysis, both for the silicon wafers and the CCC. Additionally, the changes observed in surface roughness after GD sputtering were found to be sample-dependent, changing the proportion, shape and roughness of the micro-sized patterns and holes with the sample matrix and the GD conditions.
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http://dx.doi.org/10.1007/s00216-009-3359-7DOI Listing
April 2010

Pseudotetragonal structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50): the first mixed valence cerium fluoride.

Inorg Chem 2010 Jan;49(2):686-94

Clermont Université, ENSCCF, Laboratoire des Matériaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand, France.

The crystal structure of the new Li(5.5)Ce(12)F(50) compound has been fully characterized by single-crystal and synchrotron powder X-ray diffraction. An accurate pseudotetragonal structure was described in the monoclinic P2(1) space group with 68 independent crystallographic sites. The Li(5.5)Ce(12)F(50) composition belongs to the Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) solid solution. Its structure consists of an opened fluorine framework where a channel network allows the intercalation of relatively mobile lithium cations, inducing the formation of the mixed-valence cerium (the intercalation of Li(+) leads to the reduction of a part of Ce(4+) to Ce(3+)). One part of the lithium ions, necessary for the electroneutrality of the tetravalent equivalent cerium fluoride (Li(2)Ce(12)F(50) composition), is in a locked fluorine polyhedron. Only the supplementary x amount of lithium is able to be exchanged in Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50). The structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) is a rearrangement, due to lithium intercalation, of the base CeF(4) structure. Bond valence calculation on Ce sites, Ce coordination polyhedra volumes, and a calculated Ce cationic radius give the indication of a partial long-range ordering of trivalent and tetravalent cerium cations in specific slabs of the structure. (7)Li NMR spectroscopy and XPS analyses have confirmed all of the structure details.
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http://dx.doi.org/10.1021/ic901962kDOI Listing
January 2010

[Cleft lips and palates, a multidisciplinary management].

Soins Pediatr Pueric 2005 Dec(227):20-2

Centre des fentes labiopalatines, Hôpital Robert Debré, Paris.

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December 2005

Study of a nanocomposite based on a conducting polymer: polyaniline.

Langmuir 2005 Feb;21(4):1575-83

LPCP-UMR 5067 and LCTPCM-UMR 5624, Hélioparc, 2 avenue du président Angot, 64053 Pau Cedex 9, France.

A simple way to obtain a conducting nanocomposite is described, and the conducting particles are characterized. Core-shell particles [polystyrene-polyaniline (PANI)] have been obtained by the dispersion process from three types of polystyrene latexes: a no-cross-linked core stabilized by a nonylphenolethoxylate (NP40) and two cross-linked cores stabilized by NP40 and a mixture NP40/Surfamid (a surfactant bearing an amide group). The surface of these particles has been extensively characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and scanning electron microscopy. A maximum coverage of 94% was obtained for the high PANI content as revealed by XPS analysis. A better coverage was obtained for the cross-linked polystyrene latex stabilized by the Surfamid. The amide group of this surfactant allows the H-bonding formation with the PANI backbone and, thus, improves the conductivity. It was shown that a uniform coverage of the core particles was not required to ensure a good conductivity.
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http://dx.doi.org/10.1021/la0481243DOI Listing
February 2005
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