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1.
Multilayer films ageing under ultraviolet radiations: Complementary study by dielectric spectroscopy
Simon Lewandowski Virginie Rejsek‐Riba Alain Bernès Sophie Perraud Colette Lacabanne 《应用聚合物科学杂志》2013,129(6):3772-3781
The 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. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
2.
Simon Perraud Séverine Poncet Michel Levis Emmanuelle Rouvière Claude Jaussaud 《Solar Energy Materials & Solar Cells》2009,93(9):1568-1571
A novel process was developed for integrating silicon nanowire arrays into solar cells. n-Type silicon nanowires were grown by chemical-vapour deposition via the gold-catalysed vapour-liquid-solid method, on a p-type silicon substrate. After the growth, the nanowire array was planarized, by embedding the nanowires in a spin-on glass matrix and subsequent chemical-mechanical polishing of the front surface. This planarization step allows to deposit a continuous and uniform conductive film on top of the nanowire array, and thus to form a high-quality front electrical contact. For an illumination intensity of 100 mW/cm2, our devices exhibit an energy conversion efficiency of 1.9%. The main performance limiting factor is a high pn junction reverse current, due to contamination by the growth catalyst or to a lack of passivation of surface electronic defects. 相似文献
3.
Cancer stem cell sorting from colorectal cancer cell lines by sedimentation field flow fractionation
Mélin C Perraud A Akil H Jauberteau MO Cardot P Mathonnet M Battu S 《Analytical chemistry》2012,84(3):1549-1556
Recently, cancer stem cells (CSCs) have been identified in many types of cancers, such as colorectal cancer (CRC). CSCs seem to be involved in initiation, growth, and tumor metastasis, as well as in radio- and chemotherapy failures. CSCs appears as new biological targets for cancer therapy, requiring the development of noninvasive cell sorting methods. In this study, we used sedimentation field flow fractionation (SdFFF) to prepare enriched populations of CSCs from eight cell lines corresponding to different CRC grades. On the basis of phenotypic and functional characterizations, "hyperlayer" elution resulted in a fraction overexpressing CSC markers (CD44, CD166, EpCAM) for all cell lines. CSCs were eluted in the last fraction for seven out of eight cell lines, but in the first for HCT116. These results suggest, according to the literature, that two different pools of CSCs exist, quiescent and activated, which can both be sorted by SdFFF. Moreover, according to CSC properties, enriched fractions are able to form colonies. 相似文献
4.
Alvarez J Ngo I Gueunier-Farret ME Kleider JP Yu L Cabarrocas PR Perraud S Rouvière E Celle C Mouchet C Simonato JP 《Nanoscale research letters》2011,6(1):110-9
The electrical conduction properties of lateral and vertical silicon nanowires (SiNWs) were investigated using a conductive-probe atomic force microscopy (AFM). Horizontal SiNWs, which were synthesized by the in-plane solid-liquid-solid technique, are randomly deployed into an undoped hydrogenated amorphous silicon layer. Local current mapping shows that the wires have internal microstructures. The local current-voltage measurements on these horizontal wires reveal a power law behavior indicating several transport regimes based on space-charge limited conduction which can be assisted by traps in the high-bias regime (> 1 V). Vertical phosphorus-doped SiNWs were grown by chemical vapor deposition using a gold catalyst-driving vapor-liquid-solid process on higly n-type silicon substrates. The effect of phosphorus doping on the local contact resistance between the AFM tip and the SiNW was put in evidence, and the SiNWs resistivity was estimated. 相似文献
5.
R.M. Argent J.-M. Perraud J.M. Rahman R.B. Grayson G.M. Podger 《Environmental Modelling & Software》2009,24(7):809-818
The concepts and technology of environmental decision support systems (EDSS) have developed considerably over recent decades, although core concepts such as flexibility and adaptability within a changing decision environment remain paramount. Much recent EDSS theory has focussed on model integration and re-use in decision support system (DSS) tools and for design and construction of ‘DSS generators’. Many current specific DSS have architectures, tools, models and operational characteristics that are either fixed or difficult to change in the face of changing management needs. This paper reports on development and deployment of an EDSS that encompasses a new approach to DSS tools, generators and specific DSS applications. The system, named E2, is built upon a conceptualisation of terrestrial and aquatic environmental systems that has resulted in a robust and flexible system architecture. The architecture provides a set of base classes to represent fundamental concepts, and which can be instantiated and combined to form DSS generators of varying complexity. A DSS generator is described within which system users are able to select and link models, data, analysis tools and reporting tools to create specific DSS for particular problems, and for which new models and tools can be created and, through software reflection (introspection), discovered to provide expanded capability where required. This system offers a new approach within which environmental systems can be described in the form of specific DSS at a scale and level of complexity suited to the problems and needs of decision makers. 相似文献
6.
Koester S.J. Hammond R. Chu J.O. Mooney P.M. Ott J.A. Perraud L. Jenkins K.A. Webster C.S. Lagnado I. de la Houssaye P.R. 《Electron Device Letters, IEEE》2001,22(2):92-94
The dc and microwave results of Si0.2Ge0.8/Si0.7Ge0.3 pMODFETs grown on silicon-on-sapphire (SOS) substrates by ultrahigh vacuum chemical vapor deposition are reported. Devices with Lg=0.1 μm displayed high transconductance (377 mS/mm), low output conductance (25 mS/mm), and high gate-to-drain breakdown voltage (4 V). The dc current-voltage (I-V) characteristics were also nearly identical to those of control devices grown on bulk Si substrates. Microwave characterization of 0.1×50 μm2 devices yielded unity current gain (fT) and unilateral power gain (f max) cutoff frequencies as high as 50 GHz and 116 GHz, respectively. Noise parameter characterization of 0.1×90 μm2 devices revealed minimum noise figure (Fmin) of 0.6 dB at 3 GHz and 2.5 dB at 20 GHz 相似文献
7.
A Ni/Yttria‐stabilized zirconia (YSZ) cell with a (La0.60Sr0.40)0.95Co0.20Fe0.80O3–δ cathode is tested both in fuel cell and electrolysis modes. In fuel cell mode under dry air and wet H2, the cell is operated between the open circuit voltage (OCV) and 0.4 V and reaches 330 mW cm−2 at 850 °C for 157 mL min−1 H2 supply. The influence of temperature and air or hydrogen flow rate is studied, and impedance measurements show that below 0.8 V the electrolyte becomes the more resistive part of the cell. Nevertheless, fuel utilization yields are higher under oxygen or hydrogen depletion. If it is possible at 750 °C to work at low voltage during several hours in the entire voltage range, the voltage decrease must be limited at 850 °C. The cell can also be operated under wet air. The same cell can be operated in electrolysis mode, and a power density of 340 mW cm−2 can be obtained at 0.3 V/OCV under 100 mL min−1 wet (3% H2O) 5% H2–95% Ar mixture on the fuel side and dry or wet 100 mL min−1 air flow on the air side. Nevertheless, bubbling air providing the air electrode in saltwater has an irreversible detrimental effect on the cell. 相似文献
8.
Clment Auger Aude Brunel Tiffany Darbas Hussein Akil Aurlie Perraud Gaëlle Bgaud Barbara Bessette Niki Christou Mireille Verdier 《International journal of molecular sciences》2022,23(4)
As is the case with most eucaryotic cells, cancer cells are able to secrete extracellular vesicles (EVs) as a communication means towards their environment and surrounding cells. EVs are represented by microvesicles and smaller vesicles called exosomes, which are known for their involvement in cancer aggressiveness. The release of such EVs requires the intervention of trafficking-associated proteins, mostly represented by the RAB-GTPases family. In particular, RAB27A is known for its role in addressing EVs-to-be secreted towards the the plasma membrane. In this study, shRNAs targeting RAB27A were used in colorectal (CRC) and glioblastoma (GB) cell lines in order to alter EVs secretion. To study and monitor EVs secretion in cell lines’ supernatants, nanoparticle tracking analysis (NTA) was used through the NanoSight NS300 device. Since it appeared that NanoSight failed to detect the decrease in the EVs secretion, we performed another approach to drop EVs secretion (RAB27A-siRNA, indomethacin, Nexihnib20). Similar results were obtained i.e., no variation in EVs concentration. Conversely, NTA allowed us to monitor EVs up-secretion following rotenone treatment or hypoxia conditions. Therefore, our data seemed to point out the insufficiency of using only this technique for the assessment of EVs secretion decrease. 相似文献
9.
Simon Lewandowski Virginie Rejsek‐Riba Alain Bernès Sophie Perraud Colette Lacabanne 《应用聚合物科学杂志》2016,133(41)
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). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44075. 相似文献
10.
Véronique Perraud Michael J. Lawler Kurtis T. Malecha Rebecca M. Johnson David A. Herman Norbert Staimer 《Aerosol science and technology》2013,47(9):1023-1039
Waterpipe smoking is becoming more popular worldwide and there is a pressing need to better characterize the exposure of smokers to chemical compounds present in the mainstream smoke. We report real-time measurements of mainstream smoke for carbon monoxide, volatile organic compounds and nanoparticle size distribution and chemical composition using a custom dilution flow tube. A conventional tobacco mixture, a dark leaf unwashed tobacco, and a nicotine-free herbal tobacco were studied. Results show that carbon monoxide is present in the mainstream smoke and originates primarily from the charcoal used to heat the tobacco. Online measurements of volatile organic compounds in mainstream smoke showed an overwhelming contribution from glycerol and its decomposition products. Gas phase analysis also showed that very little filtration of the gas phase products is provided by the percolation of mainstream smoke through water. Waterpipe smoking generated high concentrations of 4–100?nm nanoparticles, which were mainly composed of sugar derivatives and especially abundant in the first 10?min of the smoking session. These measured emissions of volatiles and particles are compared with those from a reference cigarette (3R4F) and represent the equivalent of the emission of one or more entire cigarettes for a single puff of hookah smoke. Considerations related to the health impacts of waterpipe smoking are discussed. 相似文献