On the use of Purcell factors for plasmon antennas

The Purcell factor is the standard figure of merit for spontaneous emission enhancement in microcavities, that has also been proposed to describe emission enhancements for plasmonic resonances. A comparison is made of quality factor, mode volume and Purcell factor for single and coupled plasmon spheres to exact calculations of emission rates. The paper explains why the Purcell factor is not appropriate for plasmon antennas.Comment: 3 pages, 2 figure

Manufacturing and impact behaviour of aeronautic overmolded grid-stiffened thermoplastic carbon plates

International audienceThermoplastic composites offer many opportunities for aeronautics. Among them is the possibility of overmolding composite parts to obtain finished “netshape” parts in medium series. This paper presents the complexity of the manufacturing method and the manufacturing defects that may occur in some grid-stiffened overmolded parts using aeronautic thermoplastics. The results of impact tests up to 15 J carried out at various locations of the plates and the grid show that, due to manufacturing defects at the overmolded grid/plate interface, very significant delaminations can be observed

A comparison of three wood species (poplar, birch and oak) for crash application

International audienc

«Matériaux vitreux auto-cicatrisants pour applications haute températures»

National audienc

RcsCDB His-Asp phosphorelay system negatively regulates the flhDC operon in Escherichia coli.

The genes involved in flagellum synthesis, motility and chemotaxis in Escherichia coli are expressed in a hierarchical fashion. At the top of the hierarchy lies the master regulator FlhDC, required for the expression of the whole set of genes. The operon flhDC is controlled by numerous regulators including H-NS, CRP, EnvZ/OmpR, QseBC and LrhA. In the present work, we report that the flhDC operon is also negatively regulated by the His-Asp phosphorelay system RcsCDB. The regulation is potentiated by the RcsB cofactor RcsA. Genetic analysis indicates that an RcsAB box, located downstream of the promoter, is required for the regulation. The binding of RcsB and RcsA to this site was demonstrated by gel retardation and DNase I protection assays. In addition, mutation analysis suggests that RcsA-specific determinants lie in the right part of the 'RcsAB box'

Wood and plywood as eco-materials for sustainable mobility: A review

Wood has always been used by man for his means of transport. It is only since the beginning of the 20th century that it has fallen into disuse due to the industrial production of concrete, steel and plastic materials. However, with global warming becoming undeniable, the societal challenge of decarbonizing transport may bring wood back into the spotlight. In this article, after a brief historical review, arguments about its availability and durability in a bio-economic context are put forward. The main mechanical properties of wood and plywood are then reviewed, along with the main factors influencing both their static and dynamic characteristics, the latter being important for the transport sector. Plywood is extensively detailed in this review paper, as it has been widely used in transport applications in the past, and presents potential optimized mechanical characteristics and eco-friendly resource utilization. Some mechanical models are also presented and put into perspective. A brief panorama of wood associations with natural or technical fibre composites is also proposed. Then, selected recent examples show that wood still has its place in naval, automotive, aeronautical, and even space applications. Finally, some conclusions are drawn and numerous research prospects in this vast and resurgent field are put forward