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Caffeic acid (CA) exhibits a myriad of biological activities including cardioprotective action, antioxidant, antitumor, anti-inflammatory, and antimicrobial properties. On the other hand, CA presents low water solubility and poor bioavailability, which have limited its use for therapeutic applications. The objective of this study was to develop a nanohybrid of zinc basic salts (ZBS) and chitosan (Ch) containing CA (ZBS-CA/Ch) and evaluate its anti-edematogenic and antioxidant activity in dextran and carrageenan-induced paw edema model. The samples were obtained by coprecipitation method and characterized by X-ray diffraction, Fourier transform infrared (FT-IR), scanning electron microscope (SEM) and UV-visible spectroscopy. The release of caffeate anions from ZBS-CA and ZBS-CA/Ch is pH-dependent and is explained by a pseudo-second order kinetics model, with a linear correlation coefficient of R2 ≥ 0.99 at pH 4.8 and 7.4. The in vivo pharmacological assays showed excellent anti-edematogenic and antioxidant action of the ZBS-CA/Ch nanoparticle with slowly releases of caffeate anions in the tissue, leading to a prolongation of CA-induced anti-edematogenic and anti-inflammatory activities, as well as improving its inhibition or sequestration antioxidant action toward reactive species. Overall, this study highlighted the importance of ZBS-CA/Ch as an optimal drug carrier.

We report on the development of all-fiber stand-alone iodine-filled photonic microcells demonstrating record absorption contrast at room temperature. The microcell’s fiber is made of inhibited coupling guiding hollow-core photonic crystal fibers. The fiber-core loading with iodine was undertaken at 10−1-10−2mbar vapor pressure using what, to the best of our knowledge, is a novel gas-manifold based on metallic vacuum parts with ceramic coated inner surfaces for corrosion resistance. The fiber is then sealed on the tips and mounted on FC/APC connectors for better integration with standard fiber components. The stand-alone microcells display Doppler lines with contrasts up to 73% in the 633 nm wavelength range, and an off-resonance insertion loss between 3 to 4 dB. Sub-Doppler spectroscopy based on saturable absorption has been carried out to resolve the hyperfine structure of the P(33)6-3 lines at room temperature with a full-width at half maximum of 24 MHz on the b4 component with the help of lock-in amplification. Also, we demonstrate distinguishable hyperfine components on the R(39)6-3 line at room temperature without any recourse to signal-to-noise ratio amplification techniques.

International audience; Acid-based geopolymers are known for their high temperature resistance and good mechanical performances. Some compositions also exhibit water resistance, which make them suitable for outdoor applications. This work aims to understand accurately the steps occurring during the geopolymerization process, and focuses on the type of networks forming at early stages of the reaction. The sample, prepared from metakaolin and phosphoric acid, has been analyzed at different durations and temperatures during its solidification, in order to identify which compounds would crystallize. The structural characterizations have been performed using Fourier Transform InfraRed spectroscopy and X-Ray diffraction. Several Al-O-P compounds and especially AlPO4 polymorphs crystallize in these conditions. They belong to three families of aluminophosphates, and are a reliable indication of the amorphous organization of the original sample. The first one is similar to the phases that appear in the phase transition sequences of silica, the second one is composed of AlPO4-based zeolites, and the last one is characterized by the presence of aluminum in an octahedral network. The transitions between the different phases are also discussed. Finally, the water resistance of the calcined samples is improved, and the release of acidic species in the water is limited even after a calcination at low temperature.

International audience; Structural and microstructural investigation on solution precursor plasma sprayed copperdoped hydroxyapatite (Cu-HA) coatings with0, 3, 5 and 10 weight percent (wt.%) of Cu dopant concentration is presented. Scanning electron micrographs show no significant morphological changes at the surface and cross-section of the coatings as copper content increases. X-ray diffraction results show decreases in the HA phase content from 93% to 14% and degree of crystallinity form 94% to 85% along with the increase of impurity phases upon increasing the copper concentration. RAMAN and IR spectra depicted broadening and red-shifting of the phosphate bands due to the distortion of the HA structure induced by the insertion of the copper ions into the HA lattice. X-ray photoelectron spectroscopy results identified that the copper species incorporated in HA structure was Cu + and Cu 2+ ions. Incorporation of copper ions into HA was associated to an interstitial insertion along hexagonal channel of the HA structure which leads to the increase in the lattice a parameter and expansion of the unit cell volume observed in Rietveld refinement measurements. The insertion was induced by the dehydroxylation process of HA due to the high temperatures of the plasma jet. Furthermore, the dopant concentration limitation in order to maintain the dominance of HA phase in the coating is 5 wt.% of Cu.

International audience; This work deals with the synthesis of zirconium dioxide (ZrO2) nanoparticles (NPs) in different solvents and their structural characterization for better understanding the oxygen donor solvent/zirconium precursor/NPs structure relationships. By selecting solvents over their capacity to produce different crystalline states from alkalinized zirconium alkoxide, spherical nanoparticles with a size of about 1.3 to 3 nm and a narrow size distribution were elaborated using a nonaqueous solvothermal sol-gel route. Conventional X-ray diffraction (XRD) was used to determine the average structure and crystallite size of the nanoparticles. Well crystallized and single-phased nanoparticles with average monoclinic and tetragonal structure were obtained with benzaldehyde and benzyl alcohol respectively, and a much distorted structure was observed for the synthesis in anisole. The atomic pair distribution functions (PDF) of the samples were also analyzed to access the local structure of the nanoparticles. The PDF of the benzaldehyde-prepared sample is consistent with the monoclinic structure. However, the local structure of nanoparticles synthesized with benzyl alcohol does not fully conform to the tetragonal structure observed by XRD but exhibits monoclinic-like distortions. Lastly, the anisole-prepared nanoparticles present large structural distortions at the medium-range and monoclinic local structural features. The restructuring of this last sample was studied by posttreatments in different solvents and leads to the expression of the tetragonal polymorph. Moreover, it seems that the main structural features are obtained in the early stages of the nanoparticles' formation.

International audience; Highlights: (maximum 85 characters, including spaces, per bullet point).  Acid-based geopolymers display different processing-dependent working properties.  Acid-based geopolymers are mostly composed of Al-O-P and Si(OH)4 networks.  The quantities of Al-O-P and unreacted metakaolin govern the thermal resistance.  The increase of the Young's modulus is related to a higher thermal resistance.  Ordered structures and low amounts of physisobed water lead to water resistance.

Federal University of Par?. Institute of Exact and Natural Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Exact and Natural Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Ananindeua, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Ananindeua, PA, Brasil. Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Exact and Natural Sciences. Bel?m, PA, Brazil. Universit? de Limoges. Centre Europ?en de la C?ramique. Laboratoire IRCER. Limoges, France Universit? de Limoges. Centre Europ?en de la C?ramique. Laboratoire IRCER. Limoges, France Universit? de Limoges. Centre Europ?en de la C?ramique. Laboratoire IRCER. Limoges, France Federal University of Par?. Institute of Biological Sciences. Bel?m, PA, Brazil. Federal University of Par?. Institute of Exact and Natural Sciences. Bel?m, PA, Brazil. Indomethacin (INDO) demonstrates therapeutic efficacy in the treatment of neuroinflammatory diseases. Despite its importance as a drug, INDO causes gastrointestinal problems and adverse reactions in the central nervous system (CNS). In this study, we prepared nanoparticles of layered double hydroxide (LDH) loaded with INDO. The structure of the nanohybrid (LDH-INDO) was synthesized via a coprecipitation method, and the nanohybrid was characterized using X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis?differential scanning colorimetry (TGA?DSC), field-emission scanning electron microscopy (FE-SEM), and ultraviolet (UV)?vis spectroscopy. Moreover, the drug release profiles of the nanohybrid were investigated using kinetic models. INDO was incorporated within the LDH interlayer space with 50% intercalation. The release of INDO anions from LDH-INDO after 10?h was 90% at pH 4.8???0.02 and 51% at pH 7.4???0.02. The results show that the release profiles follow a pseudo-second-order model. In addition, lipopolysaccharide (LPS)-induced sickness behavior in animals and treatment with INDO and LDH-INDO suggest recovery of the variables (weight and food intake) used in this study. LDH-INDO did not alter hepatic and renal biomarkers. Moreover, LPS increased the number of Iba1+ cells (microgliosis) and caused morphological alterations in these cells in the hippocampus and somatosensory cortex. However, the LPS effect was attenuated after treatment with INDO, both free and LDH-intercalated, in both regions of the brain.

Acid-based geopolymers are interesting materials, as they usually present higher mechanical and thermal properties than their alkali-based counterparts do, but they are difficult to use for complex shapes due to the high viscosity of their reactive mixture. This can be overcome by the addition of water in the formulation. In this study, geopolymers have been synthesized from metakaolin and phosphoric acid with variable [P] concentration (by a modification of either the water content or Al/P ratio). Measurements of the viscosity, density and consolidation times have been performed on reactive mixtures differentiated by their water content. Furthermore, a study of the geopolymers’ microstructure and mechanical properties confirmed their evolution with [P]. Finally, a characterization by thermal and structural analyzes of their structure (Fourier transform infrared spectroscopy and X-ray diffraction), have been carried out in order to assess the influence of the water content on the different amorphous networks. It appears that the addition of water influences the structure of the material, as it leads to the formation of new amorphous networks. More specifically, for Al/P = 1 and variable water amounts, the networks are mainly based on the coexistence of Al–O–P with an hydrated silica network, while for variable Al/P, the Al–O–P network coexists with the unreacted metakaolin. In addition, it seems that all the properties are governed by the parameter nP/nAl + nH2O.

International audience; This paper deals with the crystallization pathway of tin dioxide ultra-small nanoparticles synthesized via a nonaqueous sol-gel route based on the etherolysis of tin tetrachloride (SnCl 4) precursor. Two different ethers were used as oxygen donors: diisopropyl ether (i Pr 2 O) and dibenzyl ether (Bn 2 O). The solvothermal treatments of SnCl 4 in i Pr 2 O at different temperatures and reaction times, revealed in the early stages of the reaction the formation of an organic polymeric phase in which crystalline nanoparticles are embedded. In the case of the SnCl 4-Bn 2 O system, the formation of a brownish polymer containing crystalline oxidic nanoparticles and the production of water were evidenced. With both ethers, an unexpected intermediate disordered nano-crystalline phase is formed, which progressively transforms into rutile-type SnO 2 nanoparticles. The formation of the polymeric phase, which is suspected to act as a trap for the nanoparticles, freezes the intermediate phase, limits the particle growth and delays the restructuration into the rutile-type structure. The

In this work, the phase purity and size of zirconia nanocrystals samples were studied in terms of zirconium concentration, added water content, and subsequent use of a post solvothermal treatment. The progressive tetragonal-to-monoclinic transformation of zirconia sample was observed to be strongly related to the water content of the alcoholic medium. But more surprisingly, it has been shown that even under initially anhydrous conditions and for particle size below 5 nm, the phase purity of the samples was deteriorated by a side-reaction of alcohol dehydration catalyzed by the surface of the nanoparticles (NPs). Since the phase transformation is essentially driven by the water content of the reaction mixture, we have shown that it was possible to recover an excellent phase purity without the help of any usual dopants by adding a strong alkaline desiccating agent. Provided that a sufficient sodium to zirconium ratio was ensured, the formation of the monoclinic phase was not observed whatever the zirconium precursor concentration. The effectiveness of this cure was related to the ability of sodium metal to generate reactive alkoxide able to neutralize water and to catalyze an alternative sol-gel mechanism leading to the formation of the t-ZrO2 NPs.

In this work, the phase purity and size of zirconia nanocrystals samples were studied in terms of zirconium concentration, added water content, and subsequent use of a post solvothermal treatment. The progressive tetragonal-to-monoclinic transformation of zirconia sample was observed to be strongly related to the water content of the alcoholic medium. But more surprisingly, it has been shown that even under initially anhydrous conditions and for particle size below 5 nm, the phase purity of the samples was deteriorated by a side-reaction of alcohol dehydration catalyzed by the surface of the nanoparticles (NPs). Since the phase transformation is essentially driven by the water content of the reaction mixture, we have shown that it was possible to recover an excellent phase purity without the help of any usual dopants by adding a strong alkaline desiccating agent. Provided that a sufficient sodium to zirconium ratio was ensured, the formation of the monoclinic phase was not observed whatever the zirconium precursor concentration. The effectiveness of this cure was related to the ability of sodium metal to generate reactive alkoxide able to neutralize water and to catalyze an alternative sol-gel mechanism leading to the formation of the t-ZrO

International audience; Materials such as ceramic matrix composites are developed for mechanical applications at high temperature, but their cost remains a limitation. Consequently, the use of acid-based geopolymer matrices may be an alternative to reduce costs. In this study, the sample was prepared from metakaolin and phosphoric acid. Fourier Transform InfraRed and Nuclear Magnetic Resonance spectroscopies, X-Ray Diffraction and thermal measurements were used to understand the structural evolution of acid-based geopolymers (binders) during consolidation and after thermal treatments. According to the results, the consolidation of the binder has been divided into four steps: the dissolution of the metakaolin, the polycondensation reactions forming AlPO4 entities and hydrated phases, the breakdown of SiOAl bonds with formation of various hydrated silica networks and finally the completion of the networks. After a thermal treatment at 1000 °C, the binder consists of AlPO4 phases, quartz and vitreous silica.

Different formulations of geopolymers were synthesized in acidic media (phosphoric acid) starting from three different raw metakaolin materials to identify compositions of interest. Four different property groups were highlighted based on the most favorable thermal and water resistance properties (while maintaining acceptable mechanical properties). The groups were related to the chemical composition, setting time and setting temperature of the synthesized geopolymers. Indeed, mechanical strength was determined by chemical composition, such as the aluminum content and the amount of water in each sample. The results showed that the sample with Si/Al ≥ 1 and Al/P = 1 exhibited compressive stress to rupture values ranging between 66 and 120 MPa and was thermal resistant. Water resistance with a mechanical strength of 50 MPa was obtained for the samples with Al/P = 1 or 4 and Si/Al ≤ 1. This work highlights the possibility of selecting a specific property associated with the mechanical performance for an acidic geopolymer.

Two metakaolins exhibiting different reactivities were used to study geopolymers obtained via phosphoric acid activation. The study of consolidation of samples with various Si/Al and Al/P showed that the Al- and Si-rich and P-poor compositions were more likely to consolidate properly. The geopolymers formed at 20 or 70 °C kept the same crystalline impurities as the starting metakaolins, the samples remaining mostly amorphous. The microstructure of geopolymers formed with less reactive metakaolin was smooth and dense, while the geopolymers prepared from the most reactive one were more porous and rough. Finally, tests on water and fire resistances of all the samples were reported.

Hydroxyapatite is a bioceramic material known as orthopedic implant due to its excellent biocompatibility. From a crystallographic aspect, HA is flexible and can accommodate different ions in its structure. Zinc (Zn) is essential in the human body due to its role in many biological functions and is known to have antibacterial properties. In this work, Zn doped hydroxyapatite coatings were developed by solution precursor plasma spraying using different zinc ion concentrations. It was found that zinc addition does not modify the morphology of coatings. X-ray diffraction analysis showed that Zn concentration greater than 10 mol% inhibits the formation of HA and favors the formation of calcium zinc phosphate. Rietveld refinement showed that the unit cell parameters were not substantially changed upon Zn addition. In general, the structural analysis revealed that Zn ions were highly likely inserted at the hydroxyl column formed by the dehydroxylation of HA under high-temperature plasma environment.

We compare electromagnetically induced transparencies in large-core anti-relaxation materials inner-wall coatings Kagome HC-PCF with thermal Rb confinement in situ. A minimum transparency linewidth of ∼150 KHz in OTS coated fiber was observed.

Real nanoparticles can hardly be considered as isolated objects in vacuum with pure stoichiometric chemical composition. It can be expected that some surface stabilizing mechanisms may occur in real systems, and they could induce more or less pronounced effects on the structure of nanoparticles. In this work, we analyzed the stabilizing effect of surface impurities on the structure of ultrasmall ZrO2 nanoparticles using ab initio simulation methods. The study was performed on ZrO2 cluster models, with a diameter around 1.25 nm, using the Car–Parrinello molecular dynamics method combined with standard structural optimization methods. After the study of the naked cluster, the stabilizing effect was investigated by adding chemisorbed water molecules at the particle surface, with a covering degree ranging from 15% to 100%. The results clearly indicated that energy minimizations leaded invariably to highly disordered structures in the case of naked nanoparticles. The structure of the models got more ordered on...

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International audience; Rubidium vapor is loaded into hypocycloidal core shaped Kagome hollow-core photonic crystal fiber (HC-PCF) with the wall of its inner core coated with aluminosilicate ceramic (sol-gel). We show that the presence of Rb vapor is maintained for a longer duration when compared to uncoated Kagome HC-PCF. Rb vapor within the hollow-core of a sol-gel coated Kagome HC-PCF is preserved for over 500 h after the source of Rb is halted. And Rb vapor is detected in the sol-gel coated HC-PCF for more than 80 h after the background Rb vapor signal is no longer observed.

International audience; The solid state synthesis of phases in the Y2O3-TeO2 system under oxygen atmosphere is presented here as a method of obtaining pure material starting from simple oxides such as Y2O3 and -TeO2. In the composition range of 0-100% of TeO2, the compounds Y6TeO12, Y2TeO6, Y2Te4O11, Y2Te5O13 and Y2Te6O15 were synthesized after annealing at 770-1100 ◦C. The reactions of decomposition of the phases at higher temperatures are also reported. The crystal structure of Y6TeO12 has been refined by the Rietveld method from X-ray powder diffraction data. It crystallizes with the rhombohedral space group R-3 (S.G. no. 148) as the homologous compound In6TeO12. It is based on a three dimensional arrangement of isolated TeO6 octahedra (Te O = 1.94A° ) and edge-shared YO7 polyhedra (Y O bond lengths ranging from 2.18 to 2.65A° ).

International audience; The c-axis-oriented polycrystalline lanthanum silicate oxyapatite, La9.48(Si5.89□0.11)O26 (□ denotes a vacancy in the Si site), was successfully prepared by the reactive diffusion between randomly grain-oriented La2SiO5 polycrystal and [SiO+1/2O2] gases at 1873 K in Ar atmosphere. The polycrystal was characterized using optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, micro-Raman spectroscopy, X-ray diffractometry, and impedance spectroscopy. The crystal structure (space group P63/m) showed the deficiency of Si site at ca. 1.9%. The bulk oxide-ion conductivity along the grain-alignment direction steadily increased from 9.2 × 10−3 to 1.17 × 10−2 S/cm with increasing temperature from 923 to 1073 K. The activation energy of conduction was 0.23(2) eV.

We report on the measurement of ground state atomic polarization relaxation tile of Rb vapor confined in five different hypocycloidal core shape Kagome hollow core photonic crystal fibers made with uncoated silica glass. We are able to distinguish between wall-collision and transit-time effects in optical waveguide and deduce the contribution of the atom's dwell time at the core wall surface. In contrast with convetional macroscopic atomic cell configuration, and in agreement with Monte Carlo simulations, the measured relaxation times were found to be at least one order of magnitude longer than the limit set by the atom-wall collisional relaxation from thermal atoms. This extended relaxation time is explained by the combination of a stronger contribution of the slow atoms in the atomic polarization build-up, and of the relatively significant contribution of dwell time to the relaxation process of the ground state polarization., Comment: 8 pages, 6 pages for main text, 2 pages for supplementary materials, 4 figures

We polarized ground-state population thermal-Rb in inner-wall core-coated and uncoated Kagome HC-PCFs and measured its relaxation-time rate and its dependence with the pumping-laser intensity and detuning. Enhancement in relaxation-time in coated fibers is observed.

We prepared the highly c*-axis-aligned polycrystalline lanthanum germanate oxyapatite, La9.68Ge6O26.52, by the reactive diffusion that occurs between a randomly grain-oriented La2GeO5 polycrystal and [GeO + 1/2O2] gases at 1723 K in air. The resulting La9.68Ge6O26.52 polycrystal was examined by optical microscopy, X-ray diffractometry, micro-Raman spectroscopy, and impedance spectroscopy. The crystal structure (space group P1) showed the appreciable positional disordering of 9 of the 24 O atoms, bonding to Ge atoms, in the unit cell. We have found an extra O site, with the occupation factor of 0.51, which was located close to one of the six Ge sites with the Ge–O distance of ∼0.198 nm. The Raman extra band at 649 cm–1 also suggested the existence of the five coordinate Ge atoms. The conductivity along the c* axis of oxide ions steadily increased from 6.3 × 10–7 to 1.04 × 10–2 S/cm as the temperature increased from 573 to 973 K. The activation energy of conduction was 1.2 eV.

La (1− x ) Sr x Fe (1− y ) Ga y O 3− δ perovskites are some of the most promising materials for oxygen transport membranes due to their high oxygen semi-permeation and good chemical stability at high temperature under a wide range of oxygen partial pressures (from 0.21 to 10 −19 atm.). This paper is focused on a better understanding of the influence of the Ga and Sr substitution ratios in the La (1− x ) Sr x Fe (1− y ) Ga y O 3− δ perovskite series on oxygen semi-permeation performances, oxygen diffusion and surface exchange coefficients. This study identifies the optimal compositions of the La (1− x ) Sr x Fe (1− y ) Ga y O 3− δ perovskite series. In addition, this study shows that the rate-determining step of oxygen transport through the membrane depends strongly on the Ga and Sr substitution ratios.

International audience; a b s t r a c t Lanthanum silicated apatites with nominal composition La 9.33þx (SiO 4) 6 O 2þ3x/2 (À0.2 < x < 0.27) have been successfully synthesized by solid state reaction using a new reagent La 2 O 2 CO 3 and amorphous SiO 2 precursors. The formation mechanism of La 2 O 2 CO 3 reagent, which cannot be purchased, has been fol-lowed by in-situ temperature depend XRD of La 2 O 3 under CO 2 atmosphere. The stability of this reagent during the synthesis step allowed to limit the formation of secondary phase La 2 Si 2 O 7 and made the weighting of the reagent easier. High purity powders could be synthesized at the temperature of 1400 C. Dense pellets (more than 98.5%) were obtained by isostatic pressing of powders calcined at 1200 C and then sintered at 1550 C. Traces of La 2 SiO 5 secondary phase present in synthesized powder disappeared after densification and pure oxyapatite materials were obtained for all the compositions. Electrical measurements confirmed that conductivity behaviors of the sintered pellets were dependent to the oxygen over-stoichiometry. Indeed, a relatively high conductivity of 1 Â 10 À2 S cm À1 was exhibited at 800 C for the nominal composition La 9.60 (SiO 4) 6 O 2.405 with low activation energy around 0.79 eV. The ionic conductivity properties were comparable with that of the earlier obtained materials.

In this study, we report on the acid-catalysed synthesis of La(9.33)Si(6)O(26) from lanthanum nitrate or acetate and silicon ethoxide (TEOS) in the ethanol solvent, upon the transition from liquid to amorphous and crystalline phases. The similarity of the Fourier transform infrared spectra of the lanthanum-salt solutions and lanthanum-silicon sols indicates that the lanthanum environment is not changed in the reaction of the La-salt with TEOS. In the nitric-acid catalysed synthesis, the hydrolysis reaction was almost instantaneous, as a consequence of a higher amount of water in this system, which contributed to a high level of chemical heterogeneity in the product. The acetic acid-based synthesis ensured a good mixing of the reagents at the nanometre level, which gave rise to the formation of the pure La(9.33)Si(6)O(26) powder upon heating at 900 °C, and single phase ceramics with 94 % relative density after sintering at 1400 °C for 3 h in air, which is 200 °C lower temperature then usually reported for the apatite material.

We present aluminosilicate sol-gel coated rubidium-vapor loaded hollow core kagome fiber. We show experimentally that the rubidium vapor is preserved within the hollow core for greater than 500 hours with no vapor-source.

We measured atomic polarization relaxation-time in PDMS coated and uncoated rubidium-loaded hypocycloidal-core Kagome HC-PCF. The measured relaxation-times of 32μs and 24μs in PDMS coated and uncoated fibers are longer two-orders-of-magnitude than the wall-collision-limited relaxation time.

We report a comparative study on dephasing mechanisms between inner core coated and uncoated sections of the same Kagome hypocycloid-shaped core hollow core photonic crystal fibers (HC-PCF) filled with rubidium vapor. The comparison is performed by measuring the atomic polarization relaxation and electromagnetically induced transparency (EIT) linewidth in Rb loaded polydimethylsiloxane (PDMS) inner wall coated and bare silica core Kagome HC-PCF. The measurements show a polarization relaxation time of 32μs in a PDMS coated Kagome HC-PCF and 24μs in uncoated Kagome HC-PCF. A minimum EIT linewidth of 6.2±0.8MHz is achieved in PDMS coated Kagome HC-PCF, and 8.3±0.9 MHz for the uncoated Kagome HC-PCF.

International audience; A standalone FC/PC connectorized and sealed Iodine filled hollow core fiber with coupling efficiency as high as 75% and an absorption contrast reaching 65% on the P(33) 6-3 transition at room temperature is demonstrated.

We report on a new in-situ technique to measure dwell-time of Rb at coated surfaces of the inner-wall core of Kagome HC-PCFs. Surfaces made with silica, Alumino-silicate, PDMS and OTS were measured using this technique.

There is growing interest in using Hollow-core photonic crystal fiber (HC-PCF) in atomic based laser metrology and quantum optics [1]. Atom-filled HC-PCF represents a compact atomic vapour cell, which thanks to its long light-matter interaction distance enhances spectroscopic feature contrasts and optical nonlinearities. These advantages make atom-filled HC-PCF an outstanding candidate for numerous applications such as miniature atomic clocks, magnetometers, single photon sources, Rydberg-blockade based NOT gates, atom-light entanglement etc [1-4]. Furthermore, the small geometric core size of HC-PCF (5 to 100 μm) and large inner wall surface volume enhance atom-surface effects like physicochemical processes, surface material adsorption, Van der Waals (VW) interaction and Casimir Polder forces, which play a significant role in spectroscopic features that strongly differ from the conventional macroscopic vapor cells. Here we report on experimental observation of wall surface induced sub-Doppler transparencies in Rb-filled Kagome HC-PCF, which dramatically contrast with conventional sub-Doppler transparencies generated techniques (e.g. SAS, EIT). The present transparencies are generated by using one single laser beam injected into Rb loaded Kagome HC-PCF.

The aim of this study was to develop composites with an acid-based geopolymer matrix with mechanical properties suitable for aeronautical applications between 300 and 1000 ° C. These matrices are synthesized from metakaolin and dilute orthophosphoric acid. In order to identify the domain of stability of these matrices, their structural changes during consolidation and in temperature were analyzed by Fourier Transform and Nuclear Magnetic Resonance infrared spectroscopy as well as by X-ray diffraction, and were correlated with thermal analyzes. The objective was then to adapt the matrix formulation (consolidation temperature, [P], Al2O3 filler) to obtain a basalt fiber composite with optimal mechanical properties. Due to their poor properties, other types of oxide fibers were tested and the process parameters were adapted. Once the optimum fiber-matrix-process combination was identified, the mechanical properties of the composite were characterized at higher temperatures. The microstructure of the composites was determined by scanning electron microscopy and their mechanical properties by tensile and interlaminar shear tests.; L’objectif de cette étude a été de développer des composites à matrice géopolymère synthétisée en voie acide ayant des propriétés mécaniques adaptées aux applications aéronautiques et se conservant entre 300 et 1000 °C. Ces matrices sont synthétisées à partir de métakaolin et d’acide orthophosphorique dilué. Afin d’identifier le domaine de stabilité de ces matrices, leurs évolutions structurelles lors de la consolidation et en température ont été analysées par spectroscopie InfraRouge à Transformée de Fourrier et à Résonance Magnétique Nucléaire ainsi que par Diffraction des Rayons X et ont été corrélées aux analyses dilatométriques. La formulation de la matrice ([P], charges d’Al2O3) a ensuite été adaptée afin d’obtenir un composite à fibres de basalte aux propriétés mécaniques optimales. Compte tenu des faibles propriétés obtenues, d’autres types de fibres oxydes ont été testées et les paramètres procédés ont été adaptés. Enfin, un fois l’ensemble fibres-matrice-procédé optimal identifié, les propriétés mécaniques du composite ont été caractérisées à plus haute température. La microstructure des composites a été déterminée par microscopie électronique à balayage et leurs propriétés mécaniques par des essais de traction et de cisaillement interlaminaire.

The aim of this work was to synthesize small size (~1-3 nm) metal oxide nanocrystals namely titanium dioxide (TiO2), tin dioxide (SnO2) and zinc oxide (ZnO), and to study their structure. Syntheses were conducted via non-aqueous or even strictly non-hydrolytic sol-gel methods under kinetic control. The structural characterization was mainly carried out by X-Ray diffraction methods, transmission electronic microscopy and the study of pair distribution functions, obtained by X Ray total scattering, coupled with atomic scale modelling methods. In the case of TiO2, anatase nanocrystals were obtained with sizes ranging between 4 nm and 8 nm. The molar ratio of the oxygen donor with respect to titanium was shown to be an important parameter to control the nanoparticle size. In peculiar conditions we have been able to isolate an intermediate phase characterized by very small sized and poorly crystallized nanoparticles which the structure can be assimilated to a disordered brookite structure. Concerning SnO2, rutile-type nanocrystals were synthesized with sizes ranging between 2 nm and 4 nm. The use of an ether as oxygen donor led to the simultaneous formation of an organic polymeric phase and of primary nanoparticles characterized by an intermediate structure close but still different from the rutile-type structure. Moreover, the use of benzyl-type solvents in the presence of tin tetrachloride led to the formation of water in the system. Lastly, for ZnO, we have shown that using an organic base to induce the formation of the metal oxide network in a methanolic solution of zinc acetate in the presence of a strong complexing agent of the zinc allowed us to obtain wurtzite nanocrystals of ultrasmall sizes around 1 nm. Even for the smallest sizes, the nanoparticles exhibit a structure very close to that of wurtzite with an increasing disorder of the cationic network.; Ce travail concerne la synthèse et la caractérisation structurale de nanocristaux de faible taille (~1-3 nm) d’oxydes métalliques simples, à savoir le dioxyde de titane (TiO2), le dioxyde d’étain (SnO2) et le monoxyde de zinc (ZnO). Les synthèses ont été réalisées au moyen de méthodes sol-gel non-aqueuses voire strictement non-hydrolytiques sous contrôle cinétique. La caractérisation structurale s’est principalement appuyée sur la diffraction des rayons X, la microscopie électronique en transmission et la méthode des fonctions de distribution de paires atomiques, obtenues grâce à la diffusion totale des rayons X, couplées à des méthodes de modélisation à l’échelle atomique. Dans le cas de TiO2, des nanoparticules d’anatase bien cristallisées de 4 nm à 8 nm ont été synthétisées. Le ratio molaire de donneur d’oxygène par rapport au titane s’est avéré être un paramètre influençant fortement la taille des particules. Nous avons également mis en évidence la formation d’une phase intermédiaire caractérisée par des nanoparticules faiblement cristallisées de très faible taille dont la structure pourrait s’apparenter à une structure brookite désordonnée. Pour SnO2, des nanocristaux présentant une structure rutile ont été obtenus avec des tailles comprises entre 2 nm et 4 nm. Dans le cas de l’utilisation d’un éther, nous avons mis en évidence la formation concomitante d’une phase organique polymérisée et de nanoparticules primaires dont la structure intermédiaire présente de fortes similitudes avec la structure rutile. L’utilisation de solvants possédant une fonction benzyle en présence de tétrachlorure d’étain a conduit à la formation d’eau dans le système. Dans le cas de ZnO, nous avons montré que l’utilisation d’une base organique pour initier la formation du réseau oxyde dans une solution méthanolique d’acétate de zinc en présence d’un agent complexant du zinc permettait d’obtenir des nanoparticules de l’ordre de 1 nm. Même pour les faibles valeurs de taille, les nanoparticules présentent une structure très proche de la wurtzite avec un désordre croissant au niveau du réseau cationique.

This work deals with the synthesis and the structural characterization of zirconium oxide nanoparticles (ZrO2) as well as their size/structure relationships. We elaborated nanoparticles with a size inferior to 5 nm and a narrow size distribution using a non-hydrolytic solvothermal sol-gel route. Classical X-ray diffraction was used to evaluate the crystallite size via Rietveld refinement and X-ray total scattering to extract the pair distribution functions (PDF) of the samples for structural analysis.We succeeded in synthesizing crystalline nanoparticles of ZrO2 with a size of about 3 nm and quasi mono-dispersed. We showed that an adjusted addition of sodium hydroxide into the reaction mixture was pertinent to obtain a well crystallized and single-phase nanoparticles exhibiting an average monoclinic or tetragonal structure in benzaldehyde or in benzyl alcohol, respectively. Finally, the dilution of benzyl alcohol by anisole, an inert solvent, lead to the fine tuning of average crystallite size of the nanoparticles from 3.2 nm to 2 nm according to the TEM investigation.Those three major samples prepared in alkalinized benzaldehyde, benzyl alcohol, or anisole were subjected to complete structural analysis. According to their PDF analysis, these three samples offer an insight to the understanding of structural properties of such small particles.The experimental PDF of the benzaldehyde-prepared sample coincide with the refined PDF of a monoclinic structural model. However, the experimental PDF of the benzyl alcohol-prepared sample does not conform to any of the known polymorphs of ZrO2 having a fluorite-derived structure but rather it has an average tetragonal structure and a monoclinic distortion at the short-range order. Lastly, the experimental PDF of the anisole-prepared sample has large structural distortion at the medium-range order but has monoclinic structural features at the short-range order. We then subjected the anisole-prepared sample by thermally assisted ageing (3 to 24 days) and addition of varied amounts ex-situ water (0.3 to 5% volume content). We observed that the nanoparticles evolve from a phase containing high disorder (3 days) to a state of higher structural order (24 days) that fits with the average tetragonal structure while maintaining a monoclinic distortion at the short-range order. Similarly, the addition of ex-situ water onto the reaction mixture promoted a faster crystallization and promotes the onset of peaks that aligns with the monoclinic structure. However, the formation of monoclinic phases was inhibited by the presence of sodium hydroxide but limited to about 2% volume water content and higher than this amount lead to the formation of large particles with monoclinic structure.; Ce travail traite de la synthèse et de la caractérisation structurale de nanoparticules d'oxyde de zirconium (ZrO2) ainsi que de leurs relations taille/structure. Nous avons élaboré des nanoparticules de taille inférieure à 5 nm avec une distribution de taille étroite en utilisant une voie sol-gel non hydrolytique solvothermale. La diffraction des rayons X classique a été utilisée pour évaluer la taille des cristallites via des affinements de Rietveld et la diffusion totale des rayons X pour extraire les fonctions de distribution des paires (PDF) des échantillons et effectuer leur analyse structurale.Nous avons réussi à synthétiser des nanoparticules cristallines de ZrO2 d'une taille d'environ 3 nm et quasi mono-disperses. Nous avons montré qu'une addition d'hydroxyde de sodium dans le mélange réactionnel était pertinente pour obtenir des nanoparticules bien cristallisées et monophasées présentant une structure moyenne soit monoclinique soit tétragonale en fonction du solvant utilisé, respectivement dans le benzaldéhyde ou dans l'alcool benzylique. Enfin, la dilution de l'alcool benzylique par l'anisole, un solvant inerte, conduit au contrôle fin de la taille moyenne des nanoparticules de 3,2 nm à 2 nm selon l'étude MET.Ces trois échantillons principaux préparés dans le benzaldéhyde alcalinisé, l'alcool benzylique ou l'anisole ont été soumis à une analyse structurale complète. Selon leur analyse PDF, ces trois échantillons offrent un aperçu de la compréhension des propriétés structurales de ces petites particules.La PDF expérimental de l'échantillon préparé avec du benzaldéhyde coïncide avec la PDF affinée d'un modèle structural monoclinique. Cependant, la PDF expérimentale de l'échantillon préparé avec de l'alcool benzylique n'est conforme à aucun des polymorphes connus de ZrO2 ayant une structure dérivée de la fluorine, mais présente plutôt une structure tétragonale moyenne avec des distorsions monocliniques à l'ordre local. Enfin, la PDF expérimentale de l'échantillon préparé avec de l'anisole présente de fortes distorsions structurales dans le domaine de l'ordre à moyenne distance, mais aussi une structure de type monoclinique à l'ordre local.Ensuite, l'échantillon préparé avec l'anisole a été soumis à un vieillissement assisté thermiquement (3 à 24 jours) et on a ajouté des quantités variables d'eau ex-situ (teneur en volume de 0,3 à 5%). Nous avons observé que les nanoparticules évoluaient d'une phase contenant un désordre élevé (3 jours) à une structure mieux cristallisée (24 jours) correspondant à une structure tétragonale moyenne tout en maintenant une distorsion monoclinique à l'ordre local. De manière similaire, l'addition d'eau ex-situ sur le mélange réactionnel favorise une cristallisation plus rapide et favorise l'apparition de pics typiques de la structure monoclinique. Cependant, la formation de phase monoclinique a été inhibée par la présence d'hydroxyde de sodium, mais limitée à environ 2% en volume d'eau, et une valeur plus élevée que cette quantité conduit à la formation de grandes particules de structure monoclinique.