Influence of the environment during a photodegradation of multilayer films

The influence of different stratosphere parameters on the degradation of a multilayer film was investigated. The selected multilayer was a three polymeric layers film, a polyamide 6 film inserted between two poly(ethylene terephthalate) (PET) films. Samples were exposed for several ageing under ultraviolet radiations (filtered at 270 nm), varying the atmosphere at 55 mbar pressure (atm, atm + ozone, N2, and T = −55 °C or +23 °C). Evolution of it mechanical properties defined by uniaxial tractions, thermo-optical properties defined by spectrophotometry UV–vis-NIR, chemical properties defined by FTIR-ATR, and thermal and dielectric properties defined, respectively, by differential scanning calorimetry (DSC) and dynamical dielectric spectroscopy (DDS), were investigated. Our results showed that UV irradiation causes multilayer films degradations, that is, principally decrease of UV transmittance and stress and strain at break (−50%). An increase of the ageing temperature causes an acceleration of these degradations. Degradations principally occur on the PET side of the multilayer exposed to UV radiation. Moreover, the DDS analysis shows a plasticization effect of the primary mode in the polyamide 6 due to photo-oxidation. Oxygen diffusion is the principal element for this plasticization, indeed it not occurs in a nonoxidative environment (nitrogen), or at low ageing temperature (−55 °C)

Transitions/relaxations in polyester adhesive/PET system

The correlations between the transitions and the dielectric relaxation processes of the oriented poly(ethylene terephthalate) (PET) pre-impregnated of the polyester thermoplastic adhesive have been investigated by differential scanning calorimetry (DSC) and dynamic dielectric spectroscopy (DDS). The thermoplastic polyester adhesive and the oriented PET films have been studied as reference samples. This study evidences that the adhesive chain segments is responsible for the physical structure evolution in the PET-oriented film. The transitions and dielectric relaxation modes’ evolutions in the glass transition region appear characteristic of the interphase between adhesive and PET film, which is discussed in terms of molecular mobility. The storage at room temperature of the adhesive tape involves the heterogeneity of the physical structure, characterized by glass transition dissociation. Thus, the correlation between the transitions and the dielectric relaxation processes evidences a segregation of the amorphous phases. Therefore, the physical structure and the properties of the material have been linked to the chemical characteristics

Etude de l'interface entre deux polymères différents (Echelle microscopique et comportement macrascopique)

Le but de l'étude est de mettre en évidence la contribution des mécanismes responsables de la résistance d'un assemblage de deux polymères : un élastomère copolymère butadiène acrylonitrile hydrogéné et une polyoléfine : polyéthylène-co-octène. Ces mécanismes sont l'interdiffusion et la co-réticulation. La co-réticulation est liée à l'interface moléculaire créée lors de l'étape d'interdiffusion. La réticulation par faisceau d'électrons est utilisée pour conserver l'état d'interdiffusion. Les réseaux des deux polymères sont analysés et la formation de ponts de réticulation par irradiation est mise en évidence. La formation de ponts de réticulation interfaciaux dans les assemblages peut être proposée malgré la faible profondeur de l'interface. Afin d'augmenter la quantité d'interface, ce travail s'est orienté vers l'étude de mélanges de ces deux polymères incompatibles. La formation de ponts de réticulation peut être envisagée pour interpréter le comportement mécanique de certains mélanges.The aim of this study is to point out the contribution of the mechanisms responsable for the interfacial strength of a joint of polymers : hydrogenated nitrile butadiene rubber and a polyolefin, the copolymer of ethylene and octene. These mechanisms are the interdiffusion and co-crosslinking phenomena. The co-crosslinking is closely related to the molecular interface created during the interdiffusion step. A technique of crosslinking by electron beam is used to avoid the interdiffusion state. The network of both polymers are studied and the crosslink formation by radiation is shown. The formation of interfacial crosslinks in plane joints obtained can be proposed although the interface size is nil. In order to increase the interface quantity, the work is oriented towards the study of polymer blends. In spite of the incompatibility of the two polymers, the formation of interfacial crosslinks can be considered to interpret the mechanical behaviour of some blends.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF

Robust gene selection from microarray data with a novel Markov boundary learning method : Application to diabetes analysis

Université Lyon 1International audienc

Multilayer films ageing under ultraviolet radiations: Complementary study by dielectric spectroscopy

International audienceThe effect of ultraviolet (UV) irradiation on a multilayer film made of poly(ethylene terephthalate)/Polyamide 6/poly(ethylene terephthalate) was investigated by uniaxial tractions, UV-visible-NIR and Fourier transformed infra-red-attenuated total reflection spectroscopy, differential scanning calorimetry (DSC), and dynamic dielectric spectroscopy (DDS). The multilayer was exposed to ultraviolet radiations (filtered at 270 nm) for 7 days, in air. The complexity of the multilayer thermograms recorded by DSC and DDS has required the study of each film constituting the multilayer to assess each the contribution of each one of them. A deterioration in mechanical properties and a decrease in UV transmission for low wavelengths are observed. These evolutions seem to result to the photo-oxidation of the poly(ethylene terephthalate) film mainly localized at the exposed layer. This layer acts as a UV protection filter for the other layers. However, the DDS analyses show a plasticization effect of the primary mode in the Polyamide 6, which is evidence of photo-oxidation

Enhanced resistance to proton irradiation of poly(dimethylsiloxane) resins through surface embedding of silica photonic crystals

International audienc

Dual inhibition of BDNF/TrkB and autophagy: a promising therapeutic approach for colorectal cancer

International audienceColorectal cancer (CRC) is the most common digestive cancer in the Western world. Despite effective therapies, resistance and/or recurrence frequently occur. The present study investigated the impact of two survival pathways—neurotrophic factors (TrkB/BDNF) and autophagy—on cell fate and tumour evolution. In vitro studies were performed on two CRC cell lines, SW480 (primary tumour) and SW620 (lymph node invasion), which were also used for subcutaneous xenografts on a nude mouse model. In addition, the presence of neurotrophic factors (NTs) and autophagy markers were assessed in tissue samples representative of different stages. On the basis of our previous study (which demonstrated that TrkB overexpression is associated with prosurvival signaling in CRC cells), we pharmacologically inhibited NTs pathways with K252a. As expected, an inactivation of the PI3K/AKT pathway was observed and CRC cells initiated autophagy. Conversely, blocking the autophagic flux with chloroquine or with ATG5-siRNA overactivated TrkB/BDNF signaling. In vitro, dual inhibition improved the effectiveness of single treatment by significantly reducing metabolic activity and enhancing apoptotic cell death. These findings were accentuated in vivo, in which dual inhibition induced a spectacular reduction in tumour volume following long-term treatment (21 days for K252a and 12 days for CQ). Finally, significant amounts of phospho-TrkB and LC3II were found in the patients' tissues, highlighting their relevance in CRC tumour biology. Taken together, our results show that targeting NTs and autophagy pathways potentially constitutes a new therapeutic approach for CRC

Evaluation of Hirst-type spore traps in outdoor Aspergillaceae monitoring during large demolition work in hospital

International audienceDemolition can generate fungal spore suspensions in association with various adverse health effects, such as high risk of invasive aspergillosis in immunocompromised patients. One block of Edouard Herriot Hospital was entirely demolished. The aim of the present study was to evaluate Hirst-type spore traps utility in monitoring outdoor Aspergillaceae (Aspergillus spp. + Penicillium spp.) spores in part of Edouard Herriot Hospital (Lyon, France) undergoing major demolition. Three periods were scheduled in 2015: (A) Gutting of building and asbestos removal, (B) Demolition of floors, (C) Excavation and earthwork. Outdoor Aspergillaceae fungal load was monitored by cultivable (Air Ideal\textregistered, bioMérieux) and non-cultivable methods (Lanzoni VPPS-2000, Analyzair\textregistered, Bologna, Italy). Differences of Aspergillaceae recorded with Hirst-type spore traps were observed between Gerland and Edouard Herriot Hospital. Differences between Aspergillaceae were recorded between day time and night time at Gerland and Edouard Herriot Hospital. Daily paired differences between Aspergillaceae recorded with non-cultivable methodology at Edouard Herriot Hospital and in an area without demolition work were significant in Period A vs Period B (p = 10-4) and Period A vs Period C (p = 10-4). Weak correlation of daily Aspergillaceae recorded by both methods at Edouard Herriot Hospital was significant only for Period C (r = 0.26, p = 0.048, n = 58). Meteorological parameters and type of demolition works were found to heavily influenced Aspergillaceae dispersion. Non-cultivable methodology is a promising tool for outdoor Aspergillaceae scrutiny during major demolition work in hospital, helping infection control staff to rapidly implement control measures

Evaluation of Hirst-type spore traps in outdoor <i>Aspergillaceae</i> monitoring during large demolition work in hospital

<div><p>Demolition can generate fungal spore suspensions in association with various adverse health effects, such as high risk of invasive aspergillosis in immunocompromised patients. One block of Edouard Herriot Hospital was entirely demolished. The aim of the present study was to evaluate Hirst-type spore traps utility in monitoring outdoor <i>Aspergillaceae</i> (<i>Aspergillus</i> spp. + <i>Penicillium</i> spp.) spores in part of Edouard Herriot Hospital (Lyon, France) undergoing major demolition. Three periods were scheduled in 2015: (A) Gutting of building and asbestos removal, (B) Demolition of floors, (C) Excavation and earthwork. Outdoor <i>Aspergillaceae</i> fungal load was monitored by cultivable (Air Ideal®, bioMérieux) and non-cultivable methods (Lanzoni VPPS-2000, Analyzair®, Bologna, Italy). Differences of <i>Aspergillaceae</i> recorded with Hirst-type spore traps were observed between Gerland and Edouard Herriot Hospital. Differences between <i>Aspergillaceae</i> were recorded between day time and night time at Gerland and Edouard Herriot Hospital. Daily paired differences between <i>Aspergillaceae</i> recorded with non-cultivable methodology at Edouard Herriot Hospital and in an area without demolition work were significant in Period A vs Period B (p = 10–4) and Period A vs Period C (p = 10–4). Weak correlation of daily <i>Aspergillaceae</i> recorded by both methods at Edouard Herriot Hospital was significant only for Period C (r = 0.26, p = 0.048, n = 58). Meteorological parameters and type of demolition works were found to heavily influenced <i>Aspergillaceae</i> dispersion. Non-cultivable methodology is a promising tool for outdoor <i>Aspergillaceae</i> scrutiny during major demolition work in hospital, helping infection control staff to rapidly implement control measures.</p></div

Daily average concentrations of <i>Aspergillaceae</i> spores and colonies (spores/m³/day and CFU/m³) recorded by cultivable and non-cultivable methods during demolition at EHH, in 2015.

<p>Daily average concentrations of <i>Aspergillaceae</i> spores and colonies (spores/m³/day and CFU/m³) recorded by cultivable and non-cultivable methods during demolition at EHH, in 2015.</p