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20200316 H2020-NMBP‐35‐2017 CORES-PD/00253/2012 PD/BD/136678/2018 UIDB/ 50006/2020 UIDP/50006/2020 Cellulose nitrate (CN) is an intrinsically unstable material that puts at risk the preservation of a great variety of objects in heritage collections, also posing threats to human health. For this reason, a detailed investigation of its degradation mechanisms is necessary to develop sustainable conservation strategies. To investigate novel probes of degradation, we implemented deep UV photoluminescence micro spectral-imaging, for the first time, to characterize a corpus of historical systems composed of cellulose nitrate. The analysis of cinematographic films and everyday objects dated from the nineteenth c./early twentieth c. (Perlov's collection), as well as of photo-aged CN and celluloid references allowed the identification of novel markers that correlate with different stages of CN degradation in artworks, providing insight into the role played by plasticizers, fillers, and other additives in stability. By comparison with photoaged references of CN and celluloid (70% CN and 30% camphor), it was possible to correlate camphor concentration with a higher rate of degradation of the cinematographic films. Furthermore, the present study investigates, at the sub-microscale, materials heterogeneity that correlates to the artworks' history, associating the different emission profiles of zinc oxide to specific color formulations used in the late nineteenth and early twentieth centuries. publishersversion published

International audience; La simvastatine (SIM) est un principe actif utilisé dans le monde entier pour diminuer le tauxde cholestérol. Dans cette communication, nous présentons une étude détaillée (structure,thermodynamique et mobilité moléculaire) de la simvastatine lorsqu’elle est chargée dans unematrice de silice mésoporeuse MCM-41 (diamètre moyen des pores 3.5 nm) afin de stabiliserl'état amorphe de cette molécule et améliorer sa dissolution dans le milieu aqueux.Les investigations ont été réalisées à partir d’expériences de diffraction des rayons X, résonance magnétique nucléaire, analyse enthalpique différentielle à balayage, ATR-FTIR, spectroscopie de relaxation diélectrique et de simulations numériques de dynamique moléculaire. Nous montrons que les caractéristiques de dissolution et du profil de libération de la simvastatine confinée dans MCM-41(cf. Figure 1) résultent d’une action conjointe complexe de divers facteurs impliquant l’état physique du principe actif, l’organisation structurale des molécules, leur mobilité ainsi que leurs interactions avec la surface interne de la matrice de confinement.

International audience; Aiming to evaluate how the release profile of naproxen (nap) is influenced by its physical state, molecular mobility, and distribution in the host, this pharmaceutical drug was loaded in three different mesoporous silicas differing in their architecture and surface composition. Unmodified and partially silylated MCM-41 matrices, respectively MCM-41 and MCM-41sil, and a biphenylene-bridged periodic mesoporous organic matrix, PMOBph, were synthetized and used as drug carriers, having comparable pore sizes (∼3 nm) and loading percentages (∼30% w/w). The loaded guest was investigated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dielectric relaxation spectroscopy (DRS). DSC and XRD confirmed amorphization of a nap fraction incorporated inside the pores. A narrower glass transition was detected for PMOBph_nap, taken as an indication of the impact of host ordering, which also hinders the guest molecular mobility inside the pores as probed by DRS. While the PMOBph matrix is highly hydrophobic, the unmodified MCM-41 readily adsorbs water, accelerating the nap relaxation rate in the respective composite. In the dehydrated state, the faster dynamics was found for the silylated matrix since guest–host hydrogen bond interactions were inhibited to some extent by methylation. Nevertheless, in all the prepared composites, bulk-like crystalline drug deposits outside pores in a greater extent in PMOBph_nap. The DRS measurements analyzed in terms of conductivity show that, upon melting, nap easily migrates into pores in MCM-41-based composites, while it stays in the outer surface in the ordered PMOBph, determining a faster nap delivery from the latter matrix. On the other side, the mobility enhancement in the hydrated state controls the drug delivery in the unmodified MCM-41 matrix vs the silylated one. Therefore, DRS proved to be a suitable technique to disclose the influence of the ordering of the host surface and its chemical modification on the guest behavior, and, through conductivity depletion, it provides a mean to monitor the guest entrance inside the pores, easily followed even by untrained spectroscopists.

Background: The emergence of multidrug-resistant bacteria remains poorly understood in the wild ecosystem and at the interface of habitats. Here, we explored the spread of Escherichia coli containing IncI1-ST3 plasmid encoding resistance gene cefotaximase-Munich-1 (blaCTX-M-1) in human-influenced habitats and wild fauna using a genomic approach. Methods. Multilocus sequence typing (MLST), single-nucleotide polymorphism comparison, synteny-based analysis and data mining approaches were used to analyse a dataset of genomes and circularised plasmids. Results. CTX-M-1 E. coli sequence types (STs) were preferentially associated with ecosystems. Few STs were shared by distinct habitats. IncI1-ST3-blaCTX-M-1 plasmids are disseminated among all E. coli phylogroups. The main divergences in plasmids were located in a shuffling zone including blaCTX-M-1 inserted in a conserved site. This insertion hot spot exhibited diverse positions and orientations in a zone-modulating conjugation, and the resulting synteny was associated with geographic and biological sources. Conclusions. The ecological success of IncI1-ST3-blaCTX-M-1 appears less linked to the spread of their bacterial recipients than to their ability to transfer in a broad spectrum of bacterial lineages. This feature is associated with the diversity of their shuffling conjugation region that contain blaCTX-M-1. These might be involved in the resistance to antimicrobials, but also in their spread.

Accurate species identification often relies on public repositories to compare the barcode sequences of the investigated individual(s) with taxonomically assigned sequences. However, the accuracy of identifications in public repositories is often questionable, and the names originally given are rarely updated. For instance, species of the Sea Lettuce (Ulva spp.; Ulvophyceae, Ulvales, Ulvaceae) are frequently misidentified in public repositories, including herbaria and gene banks, making species identification based on traditional barcoding unreliable. We DNA barcoded 295 individual distromatic foliose strains of Ulva from the North-East Atlantic for three loci (rbcL, tufA, ITS1). Seven distinct species were found, and we compared our results with all worldwide Ulva spp. sequences present in the NCBI database for the three barcodes rbcL, tufA and the ITS1. Our results demonstrate a large degree of species misidentification, where we estimate that 24%–32% of the entries pertaining to foliose species are misannotated and provide an exhaustive list of NCBI sequences reannotations. An analysis of the global distribution of registered samples from foliose species also indicates possible geographical isolation for some species, and the absence of U.lactuca from Northern Europe. We extended our analytical framework to three other genera, Fucus, Porphyra and Pyropia and also identified erroneously labelled accessions and possibly new synonymies, albeit less than for Ulva spp. Altogether, exhaustive taxonomic clarification by aggregation of a library of barcode sequences highlights misannotations and delivers an improved representation of species diversity and distribution.

Tin oxide nanoparticles (SnO2 NPs) as electrocatalyst for the production of formate from CO2 reduction reaction (CO2RR). We synthesize, characterize and evaluate high surface area SnO2 NPs (2.4 nm and 299 m2 g-1 in diameter size and surface area, respectively), for the continuous production of formate at high current density within a flow electrolyzer. SnO2 NPs under Ar and CO2 reduction conditions were studied by cyclic voltammetry. SnO2-based gas diffusion electrodes (SnO2-GDEs) were manufactured to perform continuous CO2RR. A maximum formate concentration value of 27 g L-1 was achieved with a Faradaic efficiency (FE) of 44.9 % at 300 mA cm-2, which was significantly stable and reproducible when operated up to 10 h. Nevertheless, ohmic drop contribution due to the semiconducting properties of SnO2 was not negligible. The low total FE (< 60 %) of products pointed out a leakage of formate by crossover migration through the membrane from the catholyte towards the anolyte. The authors gratefully acknowledge the financial sources from the Spanish Ministry of Economy and Competitiveness (MINECO), through the project CTQ2016-76231-C2-1-R (AEI/FEDER, UE). Moreover, I.M.- G. and C.M. S.-S would like to thank the MINECO for the postdoctoral period in Paris of the predoctoral research contract (BES-2014-070081) and J. A. for the Ramón y Cajal programme (RYC-2015-17080), respectively. L.T. and O.D. acknowledge the support of French governmental funds managed by the ANR within the Investissements d’Avenir programme under reference ANR-11-IDEX-0004-02, and more specifically within the framework of the Cluster of Excellence MATISSE led by Sorbonne Universit´e. Dr. G. Gouget is strongly acknowledge for HR-TEM images.

Aiming to rationalize the release profile of an incorporated pharmaceutical drug in terms of its mobility, driven by guest-host interactions, the poorly water-soluble Ibuprofen drug was loaded in a mesoporous inorganic silica matrix with unmodified (MCM-41) and modified surface (MCM-41sil) by post-synthesis silylation, both having pore sizes ∼ 3 nm. The single calorimetric detection of a broad glass transition step for both ibuprofen composites indicates full drug amorphization, confirmed by the only appearance of an amorphous halo in the powder XRD patterns. Moreover, a gradient profile is disclosed by the heat flux derivative plot in the glass transition, in coherence with the thermogravimetric profile that shows a multi-step decomposition trace for confined ibuprofen in these matrixes. While identical guest dynamics, as probed by dielectric relaxation spectroscopy, were found in both dehydrated composites, a significant molecular population with faster relaxation exists in the hydrated state for the drug inside the unmodified matrix. This was rationalized as the concurrence of true confinement effects, which manifest under nanometer dimensions, and greater water affinity of the unmodified matrix, forcing the drug molecules to be placed mostly in the pore core. Finite size effects are also felt in both dehydrated composites, however guest-host interactions give origin to a dominant population with slowed down mobility that governs the overall guest dynamics. In spite of an inferior number of active sites for drug adsorption in the silylated matrix, a faster Ibuprofen delivery in phosphate buffer (pH = 6.8) was observed when the drug is released from unmodified MCM-41 in the hydrated state. Therefore, our results suggest that a relevant role is played by water molecules, which impair a strong guest adsorption in the host surface more efficiently than the limited surface modification, influence the higher ratio of a faster population in the pore core and facilitate the diffusion of the aqueous releasing media inside pores.

Vancomycin-resistant enterococci (VRE), due to their intrinsic resistance to various commonly used antibiotics and their malleable genome, make the treatment of infections caused by these bacteria less effective. The aims of this work were to characterize isolates of Enterococcus spp. that originated from processed meat, through phenotypic and genotypic techniques, as well as to detect putative antibiotic resistance biomarkers. The 19 VRE identified had high resistance to teicoplanin (89%), tetracycline (94%), and erythromycin (84%) and a low resistance to kanamycin (11%), gentamicin (11%), and streptomycin (5%). Based on a Next-Generation Sequencing NGS technique, most isolates were vanA-positive. The most prevalent resistance genes detected were erm(B) and aac(6')-Ii, conferring resistance to the classes of macrolides and aminoglycosides, respectively. MALDI-TOF mass spectrometry (MS) analysis detected an exclusive peak of the Enterococcus genus at m/z (mass-to-charge-ratio) 4428 &plusmn, 3, and a peak at m/z 6048 &plusmn, 1 allowed us to distinguish Enterococcus faecium from the other species. Several statistically significant protein masses associated with resistance were detected, such as peaks at m/z 6358.27 and m/z 13237.3 in ciprofloxacin resistance isolates. These results reinforce the relevance of the combined and complementary NGS and MALDI-TOF MS techniques for bacterial characterization.

The electrochemical CO2 reduction reaction (CO2RR) either to generate multicarbon (C2+) or single carbon (C1) value-added products provides an effective and promising approach to mitigate the high CO2 concentration in the atmosphere and promote energy storage. However, cost-effectiveness of catalytic materials limits practical application of this technology in the short term. Herein, we summarize and discuss recent and advanced works on cost-effective oxide-derived copper catalysts for the generation of C2+ products (hydrocarbons and alcohols) and transition metal-nitrogen-doped carbon electrocatalytic materials for C1 compounds production from CO2RR. We think they represent suitable electrocatalyst candidates for scaling up electrochemical CO2 conversion. This short review may provide inspiration for the future design and development of innovative active, cost-effective, selective and stable electrocatalysts with improved properties for either the production of C2+ (alcohols, hydrocarbons) or carbon monoxide from CO2RR. C.M. S.–S. thanks the funding of Sorbonne Université - China Scholarship Council program 2017 and Labex Matisse program (ASDB/2017-12) for the PhD contract of L. Zhang, as well as the ECOS Sud-Chile CONICYT program (Project C17E10). Thanks for the help of Dr. F. J. Recio Cortes and Dr. R. Venegas in Pontificia Universidad Católica de Chile. I.M.-G. would like to thank his postdoctoral contract in the frame of Research Project PTDC/EQU-EPQ/29579/2017, financed by ‘Programa Operacional Regional de Lisboa, na componente FEDER’ and ‘Fundação para a Ciência e Tecnologia, I.P’. J.A. gratefully acknowledge the Spanish Ministry of Economy and Competitiveness (MINECO) under Ramón y Cajal program (RYC-2015-17080).

This contribution focuses on understanding the effect of magnetic field intensity on the performance of novel hydrophilic and hydrophobic mixed matrix membranes (MMMs). The hydrophilic MMMs were made up of polymeric nanoparticles (PNPs) that were synthesized through polymerization-induced self-assembly (PISA) and iron oxide nanoparticles prepared in presence of poly (methacrylic acid)-b-poly quaternized (2-dimethylamino)ethyl methacrylate. The hydrophobic MMMs were prepared by the addition of iron oxide nanoparticles with different surface properties to a linear poly (methacrylic acid)-b-poly (methylmethacrylate) diblock copolymer dissolved in tetrahydrofuran (THF). Three different types of hydrophilic membranes were prepared with polymeric nanoparticles of different morphologies (spherical, vermicular and vesicular). In case of the hydrophobic membranes, six different membranes containing different iron oxide core coated with different stabilizers such as poly (methacrylic acid), quaternized poly(2-dimethylamino)ethyl methacrylate and meso-2,3-dimercaptosuccinic acid were prepared. An external magnetic field with intensity values up to 1.15 T was used for the permeation studies and the results were compared with those obtained in the absence of magnetic field. The collected data indicate an increase in the water flux of up to 16% and 29% under the magnetic field for hydrophobic and hydrophilic membranes, respectively. The STEM analyses suggest that the magnetic nanoparticles move within the membrane structure during the application of the magnetic field. This displacement/rearrangement causes constant changes in the membrane structure (structure of the active layer) and consequently on the membrane permeability. These results suggest that the application of the magnetic field could be used as a pretreatment step to obtain high flux membranes.

The present work is an investigation of the biological response to the presence of grooves 3 µm deep, 15 µm wide and spaced by 100 µm, produced with femtosecond laser on ß-tricalcium phosphate (ß-TCP). The heat affected zone generated by the laser irradiation was investigated. Micro-Raman spectroscopy showed a transformation from ß-TCP phase into a-TCP phase, localised inside the grooves. The X Ray Diffraction analyses, correlated with micro-Raman data, confirmed that the use of femtosecond pulsed laser enables to limit the thermal impact. A selection of optimised process parameters allowed to obtain ß-TCP micro-patterned surfaces avoiding any phase transformation. The increase of the wettability with the micro-patterning, compared to smooth surfaces, was highlighted. An improvement of the osteoblastic proliferation was also demonstrated. Finally, the tendency of cell elongation along the grooves direction showed the ability of osteoblastic cells to adapt their morphology to the support topography on which they grow. The authors are grateful to the JECS Trust for funding the visit of Marie Lasgorceix to the Laboratory INEB (Contract N°2015106). Marie Lasgorceix also acknowledges the Walloon Region for financial support, within the “BEWARE” program (convention n°1510392) co-funded by Wallonia and European Union (FP7 – Marie Curie Actions) . The authors are grateful to Dr Sylvain Desprez (Materia Nova, Mons, Belgium) for micro-Raman analyses. This publication is based on the work of COST Action MP1301, funded by COST (European Cooperation in Science and Technology) www.cost.eu .

International audience; Animal proteins are naturally 15N enriched relative to the diet and the extent of this difference (Δ15Nanimal-diet or N isotopic fractionation) has been correlated to N use efficiency (NUE; N gain or milk N yield/N intake) in some recent ruminant studies. The present study used meta-analysis to investigate whether Δ15Nanimal-diet can be used as a predictor of NUE across a range of dietary conditions, particularly at the level of between-animal variation. An additional objective was to identify variables related to N partitioning explaining the link between NUE and Δ15Nanimal-diet. Individual values from eight publications reporting both NUE and Δ15Nanimal-diet for domestic ruminants were used to create a database comprising 11 experimental studies, 41 treatments and individual animal values for NUE (n=226) and Δ15Nanimal-diet (n=291). Data were analyzed by mixed-effect regression analysis taking into account experimental factors as random effects on both the intercept and slope of the model. Diets were characterized according to the INRA feeding system in terms of N utilization at the rumen, digestive and metabolic levels. These variables were used in a partial least squares regression analysis to predict separately NUE and Δ15Nanimal-diet variation, with the objective of identifying common variables linking NUE and Δ15Nanimal-diet. For individuals reared under similar conditions (within-study) and at the same time (within-period), the variance of NUE and Δ15Nanimal-diet not explained by dietary treatments (i.e. between-animal variation plus experimental error) was 35% and 55%, respectively. Mixed-effect regression analysis conducted with treatment means showed that Δ15Nanimal-diet was significantly and negatively correlated to NUE variation across diets (NUE=0.415 -0.055×Δ15Nanimal-diet). When using individual values and taking into account the random effects of study, period and diet, the relationship was also significant (NUE=0.358 -0.035×Δ15Nanimal-diet). However, there may be a biased prediction for animals close to zero, or in negative, N balance. When using a novel statistical approach, attempting to regress between-animal variation in NUE on between-animal variation in Δ15Nanimal-diet (without the influence of experimental factors), the negative relationship was still significant, highlighting the ability of Δ15Nanimal-diet to capture individual variability. Among the studied variables related to N utilization, those concerning N efficiency use at the metabolic level contributed most to predict both Δ15Nanimal-diet and NUE variation, with rumen fermentation and digestion contributing to a lesser extent. This study confirmed that on average Δ15Nanimal-diet can predict NUE variation across diets and across individuals reared under similar conditions.

International audience; A series of mononuclear salen-supported gallium amido/alkoxide derivatives were prepared and structurally characterized and subsequently used as initiators in rac-lactide ring-opening polymerisation (ROP). The reaction of variously substituted salen ligands (1a–1f) with 0.5 equiv. of Ga2(NMe2)6 allowed the isolation of the corresponding (salen)Ga-NMe2 chelates (2b–2d, 2f) via an amine elimination route, as poorly soluble compounds in common solvents. The (salen)Ga-OBn derivatives (3a–3e) may be readily accessed by an amine-elimination/alcoholysis sequence and the molecular structures of 3a, 3d and 3e were confirmed through X-ray crystallography diffraction analysis. The present (salen)Ga-X species may effectively mediate the iso-selective ROP of rac-LA in a controlled manner (Pm up to 0.77 using a 1/1 2f/BnOH mixture as ROP initiator), with a ROP activity greatly dependent upon steric hindrance and geometrical constraints imposed by the variously substituted salen ligands. Based on the present study, salen ligands with limited steric hindrance and a certain degree of flexibility appear best suited for iso-selective ROP by (salen)Ga chelates. The salen-gallium complex 3a is also effective for the controlled ROP of ε-caprolactone (CL) and the production of PCL-b-PLA copolymers.

The host-guest chemistry of the anthocyanin analog 7-β-D-glucopyranosyloxy-4′-hydroxyflavylium (GHF) was studied in the presence of the β-cyclodextrin derivative captisol by stopped flow, UV–visible spectroscopy, flash photolysis, circular dichroism and isothermal titration calorimetry. The equilibrium and rate constants of the multistate of chemical species derived from the flavylium ion were calculated and compared with those in the absence of the host. A new procedure to obtain the host-guest association constants of the multistate (including the transient species) by superimposing the two energy level diagrams, in the presence and absence of the cyclodextrin, was developed. The results indicate that the magnitude of the association constants follows the order, trans-chalcone ≈ cis-chalcone ≈ hemiketal > quinoidal base > flavylium cation. The hydration equilibrium constant increases ca. 42 times in the presence of captisol as the hydration and dehydration rate constants respectively increases and decreases. The other equilibrium constants are modestly affected: the rate constants of ring closure and opening are significantly decreased in the complex and the isomerization rate constants increase in both directions. The quantum yield of the photochromic system in the presence of captisol is 0.3, i.e. 3 times higher than in the absence of the host.

International audience; The aim of this work is to understand the details of the interactions of ionic liquids with carbon nanomaterials (graphene and nanotubes) using polyaromatic compounds as model solutes. We have combined the measurements of thermodynamic quantities of solvation with molecular dynamics simulations to provide a microscopic view. The solubility of five polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene, pyrene and coronene) was determined in seven ionic liquids ([C4C1im][C(CN)3], [C4C1pyrr][Ntf2], [C10C1im][Ntf2], [C2C1im][C(CN)3], [C2C1im][Ntf2], [C3C1pyrr][N(CN)2] and [C4C1im][N(CN)2]) at 298 K. The enthalpies of the dissolution of naphthalene, anthracene and pyrene were measured in four of the ionic liquids. Free energies were estimated from those measurements in order to analyse the entropic or enthalpic contributions to the dissolution process. Molecular dynamics simulations provided solvation free energies that were compared to experimental and structural information. Spatial distributions of solvent ions around the solutes when combined with IR measurements elucidate the structure of solvation environments. Interactions between the imidazolium rings of cations and the π system of the solutes have been identified. However, ionic liquids with pyrrolidinium cations appeared as better solvents due to favourable enthalpic contributions compared to imidazolium cations. Long alkyl side chains on cations lead to higher solubility and lower enthalpy of dissolution by creating a “softer” solvation environment. Considering the effect of anions, small and planar anions lead to higher solubilities and lower enthalpies of dissolution of polyaromatic hydrocarbons. These findings provide the design principles based on molecular interactions and the structure of solvation environments to choose or formulate ionic liquids in view of their affinity for carbon nanomaterials.

3-Deoxyanthocyanidins and their O-β-d-glucosides are natural pigments abundant in black sorghum. O-glycosidation can perturb the acid-base properties of the chromophore and lower its electron density with a large impact on the distribution of colored and colorless forms in aqueous solution. In this work, the influence of O-glycosidation on color is systematically studied from a series of 3-deoxyanthocyanin analogs. The pH- and light-dependent reversible reactions of 7-β-d-glucopyranosyloxy-4′-hydroxyflavylium (P3) and 4′-β-d-glucopyranosyloxy-7-hydroxyflavylium (P5) were completely characterized in mildly acidic solution and compared with the parent aglycone 4′,7-dihydroxyflavylium ion and the O-methylethers of P3 and P5. Except P5, the chalcone forms of the pigments exhibit a high cis-trans isomerization barrier that allows a pseudo-equilibrium involving all species except the trans-chalcone. At equilibrium, only the flavylium cation and trans-chalcone are observed. With all pigments, the colored flavylium ion can be generated by irradiation of the trans-chalcone (photochromism). Glycosidation of C7–OH accelerates hydration and strongly slows down cis-trans isomerization with the pH dependence of the apparent isomerization rate constant shifting from a bell-shaped curve to a sigmoid. The color of P5 is much more stable than that of its regioisomer P3 in near-neutral conditions.