Study of "liquid gold" coatings : thermal decomposition and formation of metallic thin films

Organo-metallic solutions called liquid gold are largely used to obtain thin gilded films which are employed for decorative, technological and functional uses. However, these films often prove to be fragile with respect to use, resulting in loss of brilliance or even eventual film removal. An understanding of the behaviour of the layers requires good knowledge of the materials themselves. The present work was undertaken to better understand the evolution of the structural properties of liquid gold as it undergoes heat-processing. Accordingly, we followed the thermal decomposition processes of liquid gold coatings and the formation of the gilded metal layer using a combination of experimental techniques. First, thermal analyses coupled with mass spectrometry and infrared spectroscopy gave information concerning the decomposition of the organic medium. It has been found that the process of film formation can be decomposed into three steps, the second of which is an abrupt transition between 300 and 350 °C. Details on this transition have been obtained using real-time X-ray Diffraction and Rutherford Backscattering Spectrometry. Above 350 °C, the microstructure of the coating is reorganized to obtain a final layer which contains particles, of the size of a few hundreds nanometers, as shown by Transmission Electron Microscopy

Should immunosuppressives be stopped in granulomatosis with polyangiitis (Wegener's granulomatosis) patients undergoing dialysis?

Immunosuppressives are frequently stopped in patients with granulomatosis with polyangiitis (GPA) (Wegener's grantilomatosis)who develop end-stage renal disease. This is done because of the high frequency of infections reported among dialysis patients under immunosuppressives and the former impression that GPA patients no longer experience relapses after the development of end-stage renal disease. We present here a 22-year-old male patient with GPA who had gastrointestinal, genitourinary and respiratory system involvement. The patient died because of a gastrointestinal disease activation that occurred after immunosuppressives were stopped at the initiation of dialysis. The decision to stop immunosuppressives while starting dialysis should be made on an individual basis in patients with GPA, and the risks and benefits should be carefully evaluated

Experimental validation of the “FLoating Island” concept: realization of low on-resistance FLYMOS™ transistors

The present 14 volts automotive electrical system will soon become 42 volts. For these future automotive applications, development of 80 volts power MOSFETs exhibiting low on-resistance is desired. The “FLoating Island” MOSFET (FLIMOSFET) is one of the new candidates to break the silicon limit, which is the “specific on-resistance/breakdown voltage” trade-off limit of conventional power MOSFETs. In this paper, the “FLoating Island” concept has been implemented on silicon: new vertical N-channel FLIMOSFETs (FLYMOS™) dedicated to automotive applications (below 100 volts) have been fabricated for the first time, using two steps epitaxy process. Experimental results show that the FLYMOS™ transistor exhibit a breakdown voltage of 73 volts but also an improved specific on-resistance compared to conventional VDMOSFETs (33% reduction of the specific on-resistance for the same breakdown voltage). In other words, in terms of “specific on-resistance/breakdown voltage” trade-off, the FLYMOS™ transistor is one of the best MOS devices in low voltage applications. These measurements validate the “FLoating Island” concept and the efficiency of the original edge cell that is used in the FLYMOS™ technology

Alteration of lead silicate glasses due to leaching in heated acid solutions

Leaching processes were studied for lead glasses having a composition similar to that of certain archaeological materials (66 wt% PbO) to determine the mechanism of the structural evolution. The glasses were leached in two static acid media (HNO3 and CH3COOH, pH 2) at 90 °C for 35 days. Analyses were undertaken of the leaching solution (pH, inductive coupled plasma–atomic emission spectrometry) and of the bulk glass (scanning electron microscopy–energy dispersive X-ray spectrometry, Rutherford backscattering spectrometry, Raman). Results show that in both acids, up to 1 day a silicon-rich surface layer is formed via typical diffusion processes. This process continues up to 35 days in the case of acetic acid. In nitric acid, one observes a stabilisation of this layer and an increase in the metal content. In both cases, Raman data are used to interpret the structural evolutions which occur in the ‘gel' phase

Antioxidant defense gene analysis in Brassica oleracea and Trifolium repens exposed to Cd and/or Pb

International audienc

Antioxidant responses of Annelids, Brassicaceae and Fabaceae to pollutants: A review

International audienc