Laboratoire de Photochimie et d'Ingénierie Macromoléculaire

The grafting of the triangular 1,3,5-benzene tricarboxylate linkers (denoted trim) on tetrahedral ε-Keggin polyoxometalates (POMs) capped by Zn(II) ions, formed in situ under hydrothermal conditions, has generated three novel POM-based metal organic frameworks (POMOFs). (TBA)(3)[PMo(V)(8)Mo(VI)(4)O(36)(OH)(4)Zn(4)][C(6)H(3)(COO)(3)](4/3)·6H(2)O (ε(trim)(4/3)) is a 3D open-framework built of molecular Keggin units connected by trim linkers, with channels occupied by tetrabutylammonium (TBA) counterions. ε(trim)(4/3) is a novel (3,4)-connected net, named ofp for open-framework polyoxometalate, and computer simulations have been used to evaluate its relative stability in comparison with ctn- and bor-like polymorphs, showing the stability of this novel phase directly related to its greatest density. A computational study was also undertaken with the aim of locating TBA molecules, the positions of which could not be deduced from single crystal X-ray diffraction, and further rationalizes their structure directing role. In (TBA)(3)[PMo(V)(8)Mo(VI)(4)O(37)(OH)(3)Zn(4)][C(6)H(3)(COO)(3)] (ε(2)(trim)(2)), the building unit is not the molecular Keggin but a dimerized form of this POM. Their connection via trim linkers generates a 3D framework with channels filled by TBA cations. In (TBA)(3)[PMo(V)(8)Mo(VI)(4)O(37)(OH)(3)Zn(4)][C(6)H(3)(COO)(3)]·8H(2)O ([ε(trim)](∞)), zigzag chains are connected via the organic linkers, forming 2D grids. Modified electrodes were fabricated by direct adsorption of the POMOFs on glassy carbon or entrapment in carbon paste (CPE). A remarkable electrocatalytic hydrogen evolution reaction (HER) was detected with a yield greater than 95%, and a turnover number as high as 1.2 × 10(5) was obtained after 5 h. The reported POMOF-based electrodes are more active than platinum, with a roughly 260 mV anodic shift. Finally, the electrocatalytic activities of ε(trim)(4/3)/CPE electrodes in various XCl (X = Li, Na, K, Cs) media have been studied. This allowed us to detect a cation effect and propose an electrocatalytic mechanistic pathway for the HER.

Crystalline microporous solids are an important class of inorganic materials with uses in different areas impacting our everyday lives, namely as catalysts, adsorbents, and ion exchangers. Advancements in synthesis have been invaluable in expanding the classical aluminosilicate zeolites to new unique framework types and compositions, motivating innovative developments. However, the inexhaustible post-synthetic options to tailor zeolite properties have been and will continue to be indispensable to realize emerging and to improve conventional applications. Starting from the routine drying and template removal processes that every zeolite must experience prior to use, a wide spectrum of treatments exists to alter individual or collective characteristics of these materials for optimal performance. This review documents the toolbox of post-synthetic strategies available to tune the properties of zeolitic materials for specific functions. The categorisation is based on the scale at which the alteration is aimed at, including the atomic structure (e.g. the introduction, dislodgment, or replacement of framework atoms), the micropore level (e.g. template removal and functionalisation by inorganic and organic species), and the crystal and particle levels (e.g. the introduction of auxiliary porosity). Through examples in the recent literature, it is shown that the combination of post-synthetic methods enables rational zeolite design, extending the characteristics of these materials way beyond those imposed by the synthesis conditions.

Abstract— The fluorescence excitation spectrum and the excitation polarization spectrum of indole in propylene glycol were measured at — 58°C, after selecting by optical filters the emission originating from the 1 L a electronic level. From the analysis of these spectra, the excitation spectrum was resolved into the 1 L a and 1 L a excitation bands. A similar resolution of the excitation spectrum of tryptophan is given. This method can also be applied to the resolution of the emission spectrum in cases of dual emission.

The adhesion mechanisms of two acrylic Pressure-Sensitive-Adhesives on a stainless steel probe are investigated with a custom-designed probe tack apparatus. Our setup allows the simultaneous acquisition of a nominal stress and strain curve, and the observation of the adhesive film from underneath the transparent substrate. The temperature was varied in the range -20°C to 50°C and the debonding rate in the range 1–10000 μm/s. For all conditions we observed, upon debonding, the formation of cavities at or near the interface between the probe and the film. These cavities initially grew predominantly in the plane of the film but, at higher values of nominal strain, the walls between the cavities were stretched in the direction normal to the plane of the ifim to become a fibrillar structure. The transition from a cavitated structure to a fibrillar one was only found within a time-temperature window of rheological properties of the adhesive, while the adhesion energy was found to be mainly related to the elongational properties of the adhesive. The maximum tensile stress observed in the probe tack experiment was directly related to the appearance of the cavities and showed a good correlation with the shear modulus of the adhesive, while the adhesion energy was found to be mainly related to the elongational properties of the adhesive. The presence of 2% acrylic acid as a comonomer had a negligible effect on the maximum stress but a very important one on the formation of a fibrillar structure and on the locus of failure.

OBJECTIVE: To determine the effects over one year of contacting patients by telephone one month or three months after being discharged from an emergency department for deliberate self poisoning compared with usual treatment. DESIGN: Multicentre, randomised controlled trial. SETTING: 13 emergency departments in the north of France. PARTICIPANTS: 605 people discharged from an emergency department after attempted suicide by deliberate self poisoning. INTERVENTION: The intervention consisted of contacting patients by telephone at one month or three months after discharge from an emergency department for attempted suicide to evaluate the success of recommended treatment or to adjust treatment. Control patients received treatment as usual, in most cases referral back to their general practitioner. MAIN OUTCOME MEASURES: The primary outcome measures were proportion of participants who reattempted suicide, number of deaths by suicide, and losses to follow-up at 13 months' follow-up. Secondary outcome measures were types and number of contacts with health care. RESULTS: On an intention to treat basis, the three groups did not differ significantly for further suicide attempts, deaths by suicide, or losses to follow-up: contact at one month (intervention 23% (34/147) v controls 30% (93/312), difference 7%, 95% confidence interval - 2% to 15%), three months (25% (36/146) v 30%, difference 5%, - 4% to 14%). Participants contacted at one month were less likely at follow-up to report having reattempted suicide (12% v 22% in control group, difference 10%, 2% to 18%). CONCLUSION: Contacting people by telephone one month after being discharged from an emergency department for deliberate self poisoning may help reduce the number of reattempted suicides over one year.

A general procedure is described for addressing the computer simulation of protein-carbohydrate interactions. First, a molecular mechanical force field capable of performing conformational analysis of oligosaccharides has been derived by the addition of new parameters to the Tripos force field; it is also compatible with the simulation of protein. Second, a docking procedure which allows for a systematic exploration of the orientations and positions of a ligand into a protein cavity has been designed. This so-called 'crankshaft' method uses rotations and variations about/of virtual bonds connecting, via dummy atoms, the ligand to the protein binding site. Third, calculation of the relative stability of protein ligand complexes is performed. This strategy has been applied to search for all favourable interactions occurring between a lectin [concanavalin A (ConA)] and methyl alpha-D-mannopyranoside or methyl alpha-D-glucopyranoside. For each monosaccharide, different stable orientations and positions within the binding site can be distinguished. Among them, one corresponds to very favourable interactions, not only in terms of hydrogen bonding, but also in terms of van der Waals interactions. It corresponds precisely to the binding mode of methyl alpha-D-mannopyranoside into ConA as revealed by the 2.9 A resolution of the crystalline complex (Derewenda et al., 1989). Some implications of the present modelling study with respect to the molecular basis of the specificity of the interaction of lectins with various monosaccharides are presented.

The mechanical properties of polymers are strongly influenced not only by the structure of the material but by the magnitude of the molecular orientation. Thus a great deal of interest exists in information about the molecular orientation in samples introduced by drawing or other forming processes. Several techniques of evaluation of this orientation exist such as birefringence, x-ray diffraction, sonic modulus, and fluorescence measurements [l, 2]. Vibrational analysis of oriented polymers provides a method of determining independently the molecular orientation both in the crystalline and amorphous phases of polymers. By using vibrational techniques, a number of macromolecules have been studied in the solid state for a variety of different processes. It is the purpose of this review to summarize the recent theoretical and experimental results which have occurred since the review of Zbinden [3]. Infrared and Raman measurements will be reported since they are complementary to each other in their applications and results.

Abstract The photoinitiated cationic polymerization of di‐epoxy monomers has been studied using real‐time infrared (RTIR) spectroscopy. The polymerization rate and the amount of unreacted monomer were determined directly from the conversion vs. time curves recorded. The cure speed was greatly increased by using a Kr + laser (337.4 nm) as radiation source. A 0.25 s exposure proved sufficient to make react more than 60% of the epoxy groups. The overall polymerization quantum yield was evaluated to be 200 mol photon ‐1 . Dark polymerization was shown to develop extensively after the UV exposure for about 30 min and may represent up to 80% of the total process. The hardening of the UV‐cured tack‐free coating was found to occur mainly in the dark, leading after 1 h to a very hard and glassy material. A bimolecular chain termination process is postulated to account for the decay profile of the reactive species observed after UV exposure.

We have developed a tomographic diffractive microscope, equipped with a fluorescence confocal scanner. We measure experimentally the lateral resolution using an edge method and by comparing tomographic images of the same samples with wide-field and laser scanning confocal microscopy images; a scanning electron microscope image serves as a reference. The experimental resolution is shown to be to about 130 nm, or lambda/(3.5 NA). This instrument also permits one to measure 3D, complex index of refraction distributions, a quantity that is not accessible to conventional microscopes, and we show how this feature may be used to observe KCl crystals, absorption of which is very weak.

The highly virulent Escherichia coli O104:H4 that caused the large 2011 outbreak of diarrhoea and haemolytic uraemic syndrome secretes blended virulence factors of enterohaemorrhagic and enteroaggregative E. coli, but their secretion pathways are unknown. We demonstrate that the outbreak strain releases a cocktail of virulence factors via outer membrane vesicles (OMVs) shed during growth. The OMVs contain Shiga toxin (Stx) 2a, the major virulence factor of the strain, Shigella enterotoxin 1, H4 flagellin, and O104 lipopolysaccharide. The OMVs bind to and are internalised by human intestinal epithelial cells via dynamin-dependent and Stx2a-independent endocytosis, deliver the OMV-associated virulence factors intracellularly and induce caspase-9-mediated apoptosis and interleukin-8 secretion. Stx2a is the key OMV component responsible for the cytotoxicity, whereas flagellin and lipopolysaccharide are the major interleukin-8 inducers. The OMVs represent novel ways for the E. coli O104:H4 outbreak strain to deliver pathogenic cargoes and injure host cells.

Abstract. This paper presents an inverse method for inferring trace gas fluxes at high temporal (daily) and spatial (model grid) resolution from continuous atmospheric concentration measurements. The method is designed for regional applications and for use in intensive campaigns. We apply the method to a one month inversion of fluxes over Europe. We show that the information added by the measurements depends critically on the smoothness constraint assumed among the source components. We show that the initial condition affects the inversion for 20 days, provided one has enough observing sites to constrain regional fluxes. We show that the impact of the far-field fluxes grows throughout the inversion and hence a reasonable global flux field is a prerequisite for a regional inversion.

This work reports the synthesis and characterization of HDPE vitrimers obtained <italic>via</italic> reactive extrusion in the presence of bis-nitroxide dioxaborolanes.

DNA solutions subjected to an electric field exhibit an instability that leads to DNA segregation in aggregates tilted with regard to the field. With the use of epifluorescence videomicroscopy, the evolution of DNA patterns in capillaries as a function of DNA concentration, DNA size, field strength, and field frequency was studied. The field threshold for segregation was decreased when the frequency was lowered or when the DNA molecular weight or concentration was increased. Aggregation is attributed to an electrohydrodynamic instability triggered by the dipole-dipole interaction. This phenomenon explains the failure of earlier attempts to separate large DNA in capillaries.

Nanosized SAPO-34 (100–500 nm) was synthesized from colloidal solutions in the presence of tetraethylammonium hydroxide as a template at different hydrothermal (HT) conditions carried out in conventional and microwave ovens. The smallest SAPO-34 particles (∼100 nm) were obtained from the colloidal solutions with a molar composition of 1 Al 2 O 3:2 P 2 O 5:0.6 SiO 2:2 TEA 2 O:75 H 2 O using microwave energy. The stability and degree of polydispersity of the nanosized crystalline SAPO-34 product were determined by dynamic light scattering and zeta potential measurements in aqueous suspensions. The isoelectric point for the SAPO-34 particles is at pH ∼ 4 due to its acidity, which is dependent on the degree and distribution of silicon in the CHA-type framework. The effect of crystal size on the sorption properties of SAPO-34 crystals was studied by Argon physisorption at 87 K, where a high degree of textural porosity responsible for a large fraction of the total volume adsorbed is measured.

The photoredox catalysis approach is used to initiate the free radical promoted cationic photopolymerization of N -vinylcarbazole (NVK) under very soft irradiation conditions (halogen lamp, blue or green LED bulbs) using visible-light harvesting photocatalysts (mainly Ir(III) complexes) in iodonium salt and silane containing photoinitiating systems. The reactions were shown to proceed via an oxidative catalytic cycle where the generated free radicals are oxidized into cations. The effect of NVK on this catalytic cycle is discussed. Epoxy/NVK matrixes can also be polymerized. The luminescent properties of the synthesized polymers are presented.

The abilities of two naphthalimide derivatives with a methacryloyl group to initiate, when incorporated in multi-component systems, a ring-opening polymerization of epoxides and a radical polymerization of acrylates under different irradiation sources (e.g. very soft halogen lamp irradiation, laser diode at 457 nm, laser diode at 405 nm and blue LED bulb at 462 nm) have been investigated. One of them is particularly efficient for the cationic and radical photopolymerization of an epoxide/acrylate blend in a one-step hybrid cure and leads to the formation of an interpenetrated polymer network IPN (30 s for getting tack free coatings). The migration stability of one of these naphthalimide derivatives is found to be excellent in the cured polyacrylates and IPNs. The photochemical mechanisms are studied by steady state photolysis, fluorescence, cyclic voltammetry, electron spin resonance spin trapping and laser flash photolysis techniques.

Abstract Triplet state formation (Φ isc ) and properties (ε T‐T , τ T ) of phthalocyanine (HPC) and zinc phthalocyanine (ZnPC) have been characterized in homogeneous solutions (1‐chloronaphthalene, 1‐propanol) and in microemulsion by investigating the variation of the transient optical density as a function of the intensity of the exciting laser. Experimental results follow the theoretically predicted dependence only for very low intensities of the exciting pulse. At higher intensities, a more complicated scheme of primary reactions has to be taken into account, implicating qualitative restrictions in the application of saturation experiments. The observed transients at high‐intensity excitation are interpreted as being perturbed by aggregational phenomena.

Methylphenanthrene and methylchrysene distributions have been determined by Shpol'skii Spectroscopy in chromatographic fractions of various environmental samples, including Standard Reference Materials (SRM). This distribution demonstrated to be an indicator of the temperature of the formation of aromatic material in natural matrices. Specific isomer concentration ratios were calculated in each series and were proven to assess pyrolytic or petrogenic contamination in recent sediments.

Present study explains the detailed synthesis, structural characterization, antibacterial and antiviral studies on Titanium dioxide nano-colloids (TiO 2 -NCs). Titanium dioxide (TiO 2 ) nano-colloids were synthesized by a simple sonochemical method. The structural studies were carried out by x-ray Diffraction (XRD), and the size of particle was found to be 8 nm with tetragonal structure. Surface morphological results by scanning electron microscopy (SEM), showed spherical nature of (TiO 2 ) nano-colloids with almost uniform morphology. Energy Dispersive x-ray Diffraction (EDX) confirmed the chemical composition and presence of (TiO 2 ) nanoparticles in sample. Dynamic light scattering was used to confirm the colloidal stability and hydrodynamic size of nano-colloids. Antibacterial assays were performed against several gram positive and negative pathogenic bacteria. TiO 2 -NCs showed maximum bacterial inhibition (67.3 ± 2.5%) at 150 μ g ml − dose against Pseudomonas aeruginosa . Minimum inhibitory concentrations (MICs) against all tested pathogenic strains ranged from 2.24–21.21 μ g ml − , indicating efficient therapeutic potential of (TiO 2 ) nano-colloids. Antiviral activity of (TiO 2 ) nano-colloids was also performed against Newcastle virus (NDV) which showed antiviral activity at a minimum dose of 6.25 ug ml −1 . Possible mechanism of action include damage to the lipids found in viral envelop. The obtained results suggest potential application of TiO 2 -NCs in poultry to treat NDV infections after detailed mechanism studies.

The degradation of diuron photoinduced by iron(III) in aqueous solution has been investigated with different iron(III) species (monomeric species Fe(OH)2+, dimeric species Fe2(OH)24+ and water-soluble oligomeric species) under monochromatic excitation at 365 nm and under sunlight. The rate of degradation depends on the concentration in Fe(OH)2+, the most reactive species in terms of •OH radical formation. The major photoproduct is 3-(3,4-dichlorophenyl)-1-formyl-1-methylurea which represents more than 60% of diuron disappearance. The mechanism only involves the attack by •OH radicals arising from iron(III) excited species. The half-lives of diuron when submitted to such a process in the environment were estimated to be 1–2 h and a few days according to the concentration of Fe(OH)2+ (respectively 70% and <10% of total iron(III) concentration).