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Calcium carbonate whisker (CCW) particles were surface modified by grafting of poly(L-lactide) (PLLA) chains in order to improve their affinity to a poly(L-lactide-trimethylene carbonate-glycolide) (PLTG) terpolymer matrix. Composites of the PLTG matrix with CCW and PLLA-g-CCW of various contents were prepared by mixing in solution followed by solvent evaporation. The structure and properties of pure CCW, surface modified PLLA-g-CCW and PLTG/PLLA-g-CCW composites were investigated using Fourier transfer-infrared spectrometry (FT-IR), mechanical testing, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), contact angle measurement, thermal gravity analysis (TGA) and differential scanning calorimetry (DSC). Data show that PLLA chains were successfully grafted on the CCW surface. The PLTG/PLLA-g-CCW composites exhibit a higher tensile strength and elongation at break than neat PLTG. Optimal values are obtained with a PLLA-g-CCW content of 2 wt%. It is assumed that PLLA-g-CCW particles present both reinforcing and toughening effects on the PLTG matrix. The cytocompatibility of the materials was evaluated from cell morphology and MTT assay using the L929 mouse fibroblast cell line. The results indicate that the composite presents very low cytotoxicity. Therefore, PLTG/PLLA-g-CCW composites with improved mechanical properties and good cytocompatibility could be promising as a potential bone substitute material.

Accurate characterization and reporting of organic photovoltaic (OPV) device performance remains one of the important challenges in the field. The large spread among the efficiencies of devices with the same structure reported by different groups is significantly caused by different procedures and equipment used during testing. The presented article addresses this issue by offering a new method of device testing using >suitcase sample> approach combined with outdoor testing that limits the diversity of the equipment, and a strict measurement protocol. A round robin outdoor characterization of roll-to-roll coated OPV cells and modules conducted among 46 laboratories worldwide is presented, where the samples and the testing equipment were integrated in a compact suitcase that served both as a sample transportation tool and as a holder and test equipment during testing. In addition, an internet based coordination was used via plasticphotovoltaics.org that allowed fast and efficient communication among participants and provided a controlled reporting format for the results that eased the analysis of the data. The reported deviations among the laboratories were limited to 5% when compared to the Si reference device integrated in the suitcase and were up to 8% when calculated using the local irradiance data. Therefore, this method offers a fast, cheap and efficient tool for sample sharing and testing that allows conducting outdoor measurements of OPV devices in a reproducible manner., This work has been supported by the EUDP (j.no. 64012-0202), the Danish National Research Foundation, the Eurotech Universities Alliance project “Interface science for photovoltaics (ISPV)”, the European Research Infrastructure (SOPHIA), the European Energy Research Alliance (EERA), the Danish Ministry of Science, Innovation and Higher Education under a Sapere Aude Top Scientist Grant no.( DFF – 1335-00037A), an Elite Scientist Grant no.( 11-116028), MICINN-Spain(Grant # MAT2010-21267-C02-02) including FEDER funds, the UK Department for Business, Innovation & Skills, the Royal Society and the EPSRC for grants EP/G031088, EP/J500021 and EP/K030671. MN and SAC acknowledge co-funding by the European Regional Development Fund and the Republic of Cyprus through the Research Promotion Foundation (Strategic Infrastructure Project ΝΕΑ ΥΠΟΔΟΜΗ/ΣΤΡΑΤΗ/0308/06). A. E. G., R. K. M. and E.A.K. thank a financial support from the European Commission׳s Seventh Framework Program under Grant agreement no. 261936.

International audience; In January 2012, the HomePlug Alliance published the HomePlug AV2 specification. HomePlug AV2 enables gigabit-class connection speeds by leveraging the existing power line wires while remaining fully interoperable with other technologies for in-home connectivity, such as HomePlug AV, HomePlug Green PHY and IEEE 1901. In this chapter, we highlight the key differentiating HomePlug AV2 features as compared with the HomePlug AV technology. At the PHY layer, HomePlug AV2 includes the following: multiple-input-multiple-output (MIMO) signalling with beamforming ; extended frequency band up to 86 MHz ; efficient notching and power back-off to meet EMC regulations ; and EMC-friendly power boost to optimize the transmit power. At the MAC layer, HomePlug AV2 includes the following: power save mode to improve energy efficiency ; short delimiter and delayed acknowledgements to increase the overall transmission efficiency ; and immediate repeating to expand the coverage. All these features improve the quality of service of HomePlug AV2 power line modems by improving coverage and robustness of communication links. The chapter sections provide technical details for all the previously mentioned features. The chapter begins with a brief overview of HomePlug AV technology and a presentation of the overall HomePlug AV2 system architecture. Next sections detail the new PHY and MAC layers. Finally, the performance gain of HomePlug AV2 over HomePlug AV is summarized.

International audience; HomePlug AV2 is the solution identified by the HomePlug Alliance to achieve the improved data rate performance required by the new generation of multimedia applications without the need to install extra wires. Developed by industry-leading participants in the HomePlug AV Technical Working Group, the HomePlug AV2 technology provides Gigabit-class connection speeds over the existingACwireswithin home. It is designed tomeet the market demands for the full set of future in-home networking connectivity. Moreover, HomePlug AV2 guarantees backward interoperability with other HomePlug systems. In this paper, the HomePlug AV2 system architecture is introduced and the technical details of the key features at both the PHY and MAC layers are described. The HomePlug AV2 performance is assessed, through simulations reproducing real home scenarios.

International audience; Charge balance law based on conservation of charge is stated and employed to analyze on-chip linear, Fibonacci and exponential charge pumps. For micro-power on-chip implementations, both the positive- and the negative-plate parasitic capacitors have to be considered. Voltage conversion ratios and efficiencies can be obtained in closed form for single- and dual-branch linear charge pumps, but not for Fibonacci and exponential charge pumps. Instead, a first iteration approximation analysis for computing voltage conversion ratio is proposed. For the linear charge pump, efficiency optimization is achieved by first computing the optimal number of stages, and then obtaining from the required output voltage the reduction factor that is a function of load current, flying capacitor and switching frequency. Using a 0.35(m CMOS process, 8X linear, Fibonacci and exponential charge pumps are designed and their performances are compared and confirmed by extensive Cadence Spectre simulations. It is concluded that linear charge pumps attain the best efficiency.

International audience

International audience