Clermont-Ferrand’s Superior National School of Chemistry

The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H(2)O(2) concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., (•)OH, HO(2)(•)/O(2)(•-)) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO(2)(•) or O(2)(•-) radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of (•)OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions.

According to adult attachment theory, individual differences in attachment-related anxiety reflect variation in individuals' vigilance to cues relevant to appraising and monitoring the availability and responsiveness of significant others. To investigate this assumption, the authors adopted a morph movie paradigm in which participants were shown movies of faces in which an emotional facial expression changed gradually to a neutral one (Study 1) or a neutral expression changed to an emotional one (Studies 2-4). Participants were asked to judge the point at which the emotional expression had disappeared or emerged, respectively. Individuals who were highly anxious with respect to attachment were more likely to perceive the offset (Study 1) as well as the onset (Studies 2 and 3) of the facial expressions of emotion earlier than other people. Moreover, this heightened state of vigilance may have led to poorer accuracy in judging facial expressions of emotion (Study 3), an effect that was reversed when anxious individuals were required to watch the movies for the same length of time as less anxious participants (Study 4). The results indicate that variation in attachment anxiety reflects, in part, differences in vigilance to cues of social and emotional significance.

A model is introduced to predict the energy of metal-to-metal charge-transfer transitions in oxide compounds containing Bi(3+) ions and d(0) or d(10) metals (M(n+)). The model takes into account the structural characteristics of the host lattices, the anion relaxation resulting from Bi(3+) doping, and the electronegativities and coordination numbers of the Bi(3+) and M(n+) ions in the compounds. It is shown, through a critical review of the archival literature, that this model provides new insights on the assignment of the luminescence spectra and the related interpretation of the spectroscopic behaviors.

The compounds studied in this work are sol−gel-derived organic−inorganic hybrid materials in which the two components are covalently linked via Si−C bonds. The organic part is a chromophore group derived from dipicolinic acid that is functionalized with trialkoxysilyl groups; the as-obtained silylated monomers are afterward submitted to complexation with rare-earth ions (Eu3+, Gd3+) and are used as the siloxane network precursors. The preparation of hybrid materials including covalent grafting and the sol−gel process is described, as well as their luminescence properties. Modifications of the ligand structure (mono- or disubstituted amides) lead to different coordinating properties and to variable absorption edges. As a result, the absorption efficiency or the ability of the chelates to transfer the absorbed energy to Ln3+ and consequently the quantum yield of the emission are changed. The major effect of silica is a broadening of the emission peaks, whereas spectral repartitions and lifetimes are mainly unchanged as compared with the corresponding organic molecules.

Enteroviruses (EV) can cause severe neurological and respiratory infections, and occasionally lead to devastating outbreaks as previously demonstrated with EV-A71 and EV-D68 in Europe. However, these infections are still often underdiagnosed and EV typing data is not currently collected at European level. In order to improve EV diagnostics, collate data on severe EV infections and monitor the circulation of EV types, we have established European non-polio enterovirus network (ENPEN). First task of this cross-border network has been to ensure prompt and adequate diagnosis of these infections in Europe, and hence we present recommendations for non-polio EV detection and typing based on the consensus view of this multidisciplinary team including experts from over 20 European countries. We recommend that respiratory and stool samples in addition to cerebrospinal fluid (CSF) and blood samples are submitted for EV testing from patients with suspected neurological infections. This is vital since viruses like EV-D68 are rarely detectable in CSF or stool samples. Furthermore, reverse transcriptase PCR (RT-PCR) targeting the 5'noncoding regions (5'NCR) should be used for diagnosis of EVs due to their sensitivity, specificity and short turnaround time. Sequencing of the VP1 capsid protein gene is recommended for EV typing; EV typing cannot be based on the 5'NCR sequences due to frequent recombination events and should not rely on virus isolation. Effective and standardized laboratory diagnostics and characterisation of circulating virus strains are the first step towards effective and continuous surveillance activities, which in turn will be used to provide better estimation on EV disease burden.

There is accumulating evidence that strontium-containing biomaterials have positive effects on bone tissue repair. We investigated the in vitro effect of a new Sr-doped bioactive glass manufactured by the sol-gel method on osteoblast viability and differentiation. Osteoblasts isolated from foetal mouse calvaria were cultured in the presence of bioactive glass particles; particles were undoped (B75) or Sr-doped with 1 wt.% (B75-Sr1) and 5 wt.% (B75-Sr5). Morphological analysis was carried out by contrast-phase microscopy and scanning electron microscopy (SEM). Cell viability was evaluated by the MTS assay at 24 h, 48 h and 72 h. At 24 h, day 6 and day 12, osteoblast differentiation was evaluated by assaying alkaline phosphatase (ALP) activity, osteocalcin (OC) secretion and gene expression of various bone markers, using Real-Time-PCR. Alizarin Red staining and ALP histoenzymatic localisation were performed on day 12. Microscopic observations and MTS showed an absence of cytotoxicity in the three investigated bioactive glasses. B75-Sr5 particles in cell cultures, in comparison with those of B75 and B75-Sr1, resulted in a significant up-regulation of Runx2, Osterix, Dlx5, collagen I, ALP, bone sialoprotein (BSP) and OC mRNA levels on day 12, which was associated with an increase of ALP activity on day 6 and OC secretion on day 12. In conclusion, osteoblast differentiation of foetal mouse calvarial cells was enhanced in the presence of bioactive glass particles containing 5 wt.% strontium. Thus, B75-Sr5 may represent a promising bone-grafting material for bone regeneration procedures.

Fmoc-diphenylalanine (FmocFF or FmocPhePhe) is an important low molecular weight hydrogelator. Gelation can be induced by either lowering the pH of an aqueous solution of FmocFF or by the addition of water to a solution of FmocFF in a solvent such as DMSO. Despite the volume of literature on FmocFF, the mechanical properties reported for the gels vary significantly over four orders of magnitude and the origins of this variability is unclear. Here, we study systematically the mechanical properties of FmocFF gels prepared with different protocols. We demonstrate that the final pH of the gels is the principal determinant of the mechanical properties independently of the method of gel formation. We also show that additional variability arises from experimental factors such as the fraction of DMSO or the nature of the buffers used in selected systems.

The goal of this paper was to develop a modified photo-Fenton treatment able to degrade micro pollutants in municipal wastewater treatment plant (MWTP) effluents at a neutral pH with minimal iron and H(2)O(2) concentrations. Complexation of Fe by ethylenediamine-N,N'-disuccinic acid (EDDS) leads to stabilization and solubilization of Fe at natural pH. Photo-Fenton experiments were performed in a pilot compound parabolic collector (CPC) solar plant. Samples were treated with solid phase extraction (SPE) and analyzed by HPLC-Qtrap-MS. The rapid degradation of contaminants within the first minutes of illumination and the low detrimental impact on degradation of bicarbonates present in the water suggested that radical species other than HO(•) are responsible for the efficiency of such photo-Fenton process. Disinfection of MWTP effluents by the same process showed promising results, although disinfection was not complete.

In this work, we report the solvothermal synthesis of Ce-doped YAG (YAG:Ce) nanoparticles (NPs) and their association with a free-Cd CuInS2/ZnS (CIS/ZnS) core/shell QDs for application into white light emitting diode (WLED). 1500 °C-annealed YAG:Ce NPs and CIS/ZnS core/shell QDs exhibited intense yellow and red emissions band with maxima at 545 and 667 nm, respectively. Both YAG:Ce nanophosphor and CIS/ZnS QDs showed high photoluminescence quantum yield (PL QY) of about 50% upon 460 nm excitation. YAG:Ce nanophosphor layer and bilayered YAG:Ce nanophosphor-CIS/ZnS QDs were applied on blue InGaN chip as converter wavelength to achieve WLED. While YAG:Ce nanophosphor converter layer showed low color rendering index (CRI) and cold white light, bilayered YAG:Ce nanophosphor-CIS/ZnS QDs displayed higher CRI of about 84 and warm white light with a correlated color temperature (CCT) of 2784 K. WLED characteristics were measured as a function of forward current from 20 to 1200 mA. The white light stability of bilayered nanophosphor-QDs-based WLED operated at 200 mA was also studied as a function of operating time up to 40 h. Interestingly, CRI and CCT of such device tend to remain constant after 7 h of operating time suggesting that layer-by-layer structure of YAG:Ce phosphor and red-emitting CIS/ZnS QDs could be a good solution to achieve stable warm WLED, especially when high current density is applied.

An ordered network of interconnected tin oxide (SnO 2 ) nanoparticles with a unique 3D architecture and an excellent lithium‐ion (Li‐ion) storage performance is derived for the first time through hydrolysis and thermal self‐assembly of the solid alkoxide precursor. Mesoporous anodes composed of these ≈9 nm‐sized SnO 2 particles exhibit substantially higher specific capacities, rate performance, coulombic efficiency, and cycling stabilities compared with disordered nanoparticles and commercial SnO 2 . A discharge capacity of 778 mAh g –1 , which is very close to the theoretical limit of 781 mAh g –1 , is achieved at a current density of 0.1 C. Even at high rates of 2 C (1.5 A g –1 ) and 6 C (4.7 A g –1 ), these ordered SnO 2 nanoparticles retain stable specific capacities of 430 and 300 mAh g –1 , respectively, after 100 cycles. Interconnection between individual nanoparticles and structural integrity of the SnO 2 electrodes are preserved through numerous charge–discharge process cycles. The significantly better electrochemical performance of ordered SnO 2 nanoparticles with a tap density of 1.60 g cm –3 is attributed to the superior electrode/electrolyte contact, Li‐ion diffusion, absence of particle agglomeration, and improved strain relaxation (due to tiny space available for the local expansion). This comprehensive study demonstrates the necessity of mesoporosity and interconnection between individual nanoparticles for improving the Li‐ion storage electrochemical performance of SnO 2 anodes.

Single crystals of CaWO(4) and CaMoO(4) doped with Tb(3+) have been grown by the flux growth method. Their luminescence properties have been investigated in the 10-600 K temperature range under different experimental conditions. In spite of very similar spectra at low temperature upon excitation at 365 nm, the crystals show a very different behavior as the temperature is raised or the excitation wavelength is changed. These differences have been accounted for on the basis of models that take into consideration the position of the energy levels of the rare earth relative to the bandgap of the host material.

It is shown here that carbamazepine (CBZ) would undergo direct photolysis and reaction with (•)OH as the main phototransformation pathways in surface waters. Environmental lifetimes are expected to vary from a few weeks to several months, and predictions are in good agreement with available field data. Acridine (I) and 10,11-dihydro-10,11-trans-dihydroxy-CBZ (V) are the main quantified phototransformation intermediates upon direct photolysis and (•)OH reaction, respectively. The photochemical yield of mutagenic I from CBZ is in the 3-3.5% range, and it is similar for both direct photolysis and (•)OH reaction: it would undergo limited variation with environmental conditions. In contrast, the yield of V would vary in the 4-8.5% range depending on the conditions, because V is formed from CBZ by (•)OH (9.0% yield) more effectively than upon direct photolysis (1.4% yield). Other important photointermediates, mostly formed from CBZ upon (•)OH reaction, are an aromatic-ring-dihydroxylated CBZ (VI) and N,N-bis(2-carboxyphenyl)urea (VII). Compounds VI and VII are formed by photochemistry and are not reported as human metabolites; thus, they could be used as tracers of CBZ phototransformation in surface waters. Interestingly, VI has recently been detected in river water.

Addition of divalent cations to a solution of a naphthalene-diphenylalanine that forms worm-like micelles at high pH results in the formation of a rigid, self-supporting hydrogel.

This study reports the effect of light on PLA/ZnO nanocomposites films produced by melt-extrusion. The attention focused on the discrimination between the photocatalytic degradation of PLA provoked by ZnO and the UV screening effect of the ZnO nanoparticles. The chemical modifications of PLA induced by UV light irradiation were analyzed using infrared spectroscopy and completed through the analysis of the low-molecular-weight photoproducts using IC and SPME and the characterization of chain scissions with SEC. A comprehensive mechanism for the photooxidation of PLA was then proposed. The results indicated that the photocatalytic activity of ZnO nanoparticles induces the oxidation of PLA. Because ZnO limits the penetration of light inside the samples, this effect mainly concerns the first micrometers at the surface of the exposed samples. Cross-sectional analysis using micro-IR and ATR-IR spectroscopies was performed to highlight the degradation profile in the PLA/ZnO nanocomposites.

The validity of a simple, reliable, and useful recently published formula enabling to calculate the maximum volumetric biomass productivities in photobioreactors (PBRs) was investigated through the cultivation of the microalga Chlamydomonas reinhardtii. Experimental maximum kinetic performances accurately obtained in two different, artificially lightened torus-plane and cylindrical reactors having the same specific illuminated area confirmed the availability, power, and robustness of such formula. The predictive kinetic parameters previously proposed and validated with cyanobacteria were then proved general and robust in case of eukaryotic microalgae, as postulated in the founding article. In this case, an additional criterion requiring rigorous control of the working illuminated fraction gamma = 1 +/- (15%) inside the reactor is demonstrated. For this, the usefulness and reliability of a generalized two-flux model accurately describing the radiation field inside turbid culture media of C. reinhardtii were also established in this article. These important results contribute to identify the main engineering factors governing light-limited PBRs functioning and then to clarify some misinterpretations widely reported in the literature. Together with the referenced previous work, this article gives a framework toward optimal conception of PBRs on a strong physical basis.

Tobacco smoke residues lingering in the indoor environment, also termed thirdhand smoke (THS), can be a source of long-term exposure to harmful pollutants. THS composition is affected by chemical transformations and by air-surface partitioning over time scales of minutes to months. This study identified and quantified airborne THS pollutants available for respiratory exposure, identified potential environmental tracers, and estimated health impacts to nonsmokers. In a ventilated 18 m(3) laboratory chamber, six cigarettes were machine-smoked, and levels of particulate matter (PM2.5) and 58 volatile organic compounds (VOCs) were monitored during an aging period of 18 h. Results were compared with field measurements taken in a smoker's home 8 h after the last cigarette had been smoked. Initial chamber levels of individual VOCs in freshly emitted secondhand smoke (SHS) were in the range of 1-300 μg m(-3). The commonly used SHS tracers 3-ethenylpyridine (3-EP) and nicotine were no longer present in the gas phase after 2 h, likely due mostly to sorption to surfaces. By contrast, other VOCs persisted in the gas phase for at least 18 h, particularly furans, carbonyls, and nitriles. The concentration ratio of acetonitrile to 3-EP increased substantially with aging. This ratio may provide a useful metric for differentiating freshly emitted (SHS) from aged smoke (THS). Among the 29 VOCs detected in the smoker's home at moderate to high concentrations, 18 compounds were also detected in simultaneously sampled outdoor air, but acetonitrile, 2-methyl furan, and 2,5-dimethyl furan appeared to be specific to cigarette smoke. The levels of acrolein, methacrolein, and acrylonitrile exceeded concentrations considered harmful by the State of California. An initial exposure and impact assessment was conducted for a subset of pollutants by computing disability-adjusted life years lost, using available toxicological and epidemiological information. Exposure to PM2.5 contributed to more than 90% of the predicted harm. Acrolein, furan, acrylonitrile, and 1,3-butadiene were considered to be the most harmful VOCs. Depending on which criteria are used to establish the separation between SHS and THS, 5-60% of the predicted health damage could be attributed to THS exposure. Benefits and limitations of this approach are discussed.

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels.

The development of chalcones as antimitotic agents has led to the design of other analogues able to interact with tubulin and inhibit its assembly into microtubules. This activity has also been associated with their anti-vascular activity. This review focuses on the development of chalcones and related analogues as antimitotic agents.

Polyvinyl alcohol (PVA) is a water-soluble polymer that is anticipated to be a good candidate for incorporation into multilayer coatings of organic solar cells due to its high transparency and ability to form a barrier to oxygen. Because a long lifetime is a prerequisite for successful applications, it was necessary to study the photochemical behavior of PVA under solar light. PVA films were exposed to UV-visible light irradiation (λ > 300 nm) in accelerated aging conditions representative of natural ageing. Modifications in the chemical structure of aged samples irradiated at ambient air were recorded. Due to the low oxygen permeability of PVA films, it was shown that the photooxidative degradation of PVA films is restricted to the surface (<5 μm) and results in a large amount of chain scissions, with a progressive erosion of the surface of the irradiated material. The oxidation products formed along the macromolecular chains, and low molecular weight species trapped in the matrix or emitted in the gas phase were also identified. An oxidation mechanism was then proposed to account for these modifications. However, irradiation in the absence of oxygen demonstrated the high photostability of PVA films, which permits the use of PVA as a sublayer in inorganic/organic multilayer encapsulation systems.

The impact of selected cellulose solvent systems based on the principal constituents tetrabutylammonium fluoride (TBAF), 1-ethyl-3-methyl-1H-imidazolium-acetate, N-methylmorpholine-N-oxide, or calcium thiocyanate octahydrate (CTO) on the properties of cellulose II aerogels prepared from these solvent systems has been investigated as a means towards tailoring cellulose aerogel properties with respect to specific applications. Cotton linters were used as representative plant cellulose. Cellulose was coagulated from solutions with comparable cellulose content, and dried with supercritical carbon dioxide after solvent exchange. The resulting bulk aerogels were comprehensively morphologically and mechanically tested to relate structure and mechanical properties. Different solvent systems caused considerable differences in the properties of the bulk samples, such as internal surface area (nitrogen sorption), morphology, porosity (He pycnometry, thermoporosimetry), and mechanical stability (compression testing). The results of SAXS, WAXS, and solid-state 13C NMR spectroscopy suggest that this is due to different mechanisms of cellulose self-assembling on the supramolecular and nanostructural level, respectively, as reflected by the broad ranges of cellulose crystallinity, fibril diameter, fractal dimension and skeletal density. Both solid state NMR and WAXS experiments confirmed the sole existence of the cellulose II allomorph for all aerogels, with crystallinity reaching a maximum of 46–50 % for CTO-derived aerogels. Generally, higher fibril diameter, degree of crystallinity, hence increased skeletal density were associated with good preservation of shape and dimension throughout conversion of lyogels to aerogels, and enhanced mechanical stability, but somewhat reduced specific surface area. Amorphous, yet highly rigid aerogels derived from TBAF/DMSO mixtures deviated from this trend, most likely due to their particular homogeneous and nanostructured morphology.