Thermoelectric generators enable the direct conversion from heat into electrical power whatever the nature of the heat source. Therefore, they provide an effective route to use waste heat originating from automobiles, incinerators and so on, to produce clean electrical power. Until the very recent years, the main drawback of these systems has been their poor energy conversion efficiency that made them unsuitable for widely used applications. However, a great effort of research has been devoted in the past decade to the development of novel materials with improved performances. Consequently, the annual number of submitted patents that deal with thermoelectric conversion systems or thermoelectric materials has grown very rapidly. The efficiency of a thermoelectric material used for power generation increases with the so-called dimensionless figure of merit ZT defined as ZT = S²T/rl, where S is the Seebeck coefficient or thermopower, r the electrical resistivity, and l the thermal conductivity. It is generally considered that a figure of merit higher than unity is required for efficient thermoelectric energy conversion. ZT=1 for both p type and n type materials of an ideal thermoelectric device would allow for example a 10% recovery of the heavy trucks exhaust gas waste energy. In recent years, several families of materials with ZT>1 have been developed, including for example skutterudites, magnesium silicides…, and it has been demonstrated that thermoelectric modules based on these materials can reach about 10% efficiency. However, there is still a need of more efficient thermoelectric materials which would enlarge the number of possible applications or open new markets. During the 1990s and 2000s, oxychalcogenides materials with general formula RCuChO (R = trivalent cation, Ch = S, Se or Te) have been widely studied first as possible parent compounds for new high-Tc superconductors and then as potential p-type transparent conducting materials for optoelectronic applications, mostly in the thin film form. In the beginning of 2008, an intense research activity emerged dealing with the study of a new family of superconductors: the iron-oxypnictides. Following the discovery of superconductivity in these materials, we initiated an exploratory research in this field. We were the first to show that these materials not only exhibit, beside fascinating superconducting properties, promising thermoelectric properties. Their Seebeck coefficient can be larger than 120 µV.K-1 around 100K and they exhibit good electrical properties. As a matter of fact, we have shown that their electrical transport properties, in the liquid nitrogen temperature range, are not far from those of the best materials known to date based on BiSb alloys. Following this discovery, we have expanded our study to the oxychalcogenides family, and we have shown that these materials exhibit very promising thermoelectric performances in the 400-650°C temperature range and that they could be used in mid-temperature thermoelectric energy converters. The main topic of this project is to study the thermoelectric properties of oxychalcogenides materials in order to assess their potential as p-type thermoelectric materials and to optimize them for applications in thermoelectric modules.

The project detailed in this proposal deals with asymmetric organic transformations using chiral d transition metal- and lanthanide-based catalysts. We hypothesize that enolates can add to unactivated olefins in an enantioselective fashion, using bimetallic activation. To achieve this goal, we reason that a lanthanide complex can be used as strong sigma-Lewis acid to activate the carbonyl functionality of a pronucleophile and generate an enolate (or a complexed enol), while a soft pi-Lewis acid, incorporating for instance gold or platinum, activates the olefin toward nucleophilic attack. The chirality could be borne by either complex. The result of such a reaction would be comparable to an asymmetric Michael addition, yet applied to simple alkenes. The development of this reaction would pave the way for total syntheses of natural products.

Silicon photonics has generated an increasing interest in the recent years. The integration of optics and electronics on a same chip would allow the enhancement of integrated circuit performances, and optical telecommunications can benefit from the development of low cost and high performance solutions for high-speed optical links. Silicon based-optoelectronic devices are the key building blocks for the development of silicon photonics. Despite the demonstration of high performance silicon modulator, germanium photodetectors, and the achievement of optical sources using III-V material bonded on silicon, the integration of these different elements on an electronic chip is highly challenging due to the different materials and technologies for each building block. In addition, wideband silicon modulators require active regions longer than 1 mm which makes their integration on electronic chips difficult. Finally an effective silicon based light source is still the Holy Grail for silicon photonics researchers. The real development of silicon photonics needs to solve these challenging points, and this will be possible only by using innovative breaking concepts. In this context, GOSPEL project propose to study direct gap-related optical properties of Ge/SiGe multiple quantum wells (MQW). Indeed, in 2005, photocurrent spectroscopy has been used to demonstrate that Quantum Confined Stark Effect (QCSE) can be obtained in Ge/SiGe quantum wells (QW), which is an important breakthrough as it was the first demonstration of using direct gap related effect in indirect bandgap materials. This demonstration has paved the way for a lot exciting works related to a good understanding of the mechanisms in these Ge/SiGe QW structures and for the achievement of innovative optoelectronic devices based on these mechanisms. In this context the goal of GOSPEL project is to study physical, optical and optoelectronic properties of Ge/SiGe multiple quantum wells to go towards photonic devices. The structures are grown by low energy plasma enhanced chemical vapour deposition (LEPECVD), in L-Ness lab (Como - Politecnico di Milano, Italy) thanks to collaboration with Giovanni Isella’s group. Due to the large lattice mismatch between Si and Ge, a graded SiGe buffer is used, with Ge concentration of SiGe layer grown from zero to the final concentration with a continuous change to obtain a relaxed Ge-rich SiGe layer, where high quality Ge/SiGe quantum wells can be grown. Indeed the preliminary results allowed us to demonstrate QCSE at room temperature for light incident perpendicular and for the first time parallel to the QW planes, which is directly related to integrated photonic applications. In GOSPEL project, material properties (energy and intensity of excitonic peaks, carrier dynamics and transport) and optoelectronic properties (influence of external electric field, luminescence) of Ge/SiGe MQW structures will be compared to theoretical results, in order to improve the understanding of physical properties in these structures. Devices based on these new effects will be designed and fabricated in order to experimentally observe light modulation, detection, and emitting properties of the Ge/SiGe MQW structures. GOSPEL project will then give answers on the possibilities and opportunities to develop a new and innovative Ge/SiGe photonics platform.

Many chemicals have been shown to be allergens leading to contact or respiratory allergy and therefore pose serious health risks. Dendritic cells (DC) present in peripheral organs such as the skin or the lung are capable to take up and to process allergens. After processing antigens, they differentiate into mature, immunostimulatory cells. In addition of antigen processing, DC need to received signals through Toll-like receptors (TLR) to achieve maturation. These signals are provided by the so-called “danger signals” mainly composed of pathogen-associated molecular patterns recognised by TLRs. Our current work is based on the hypothesis that considering similarities between immunity to simple chemicals and that to infectious agents, it is reasonable to speculate that hapten itself stimulates DC maturation and that chemicals sensitizers could be perceived by DC as “danger signals” with common signaling pathways leading to DC maturation and migration. The main objective of this project is to understand and to characterize how chemical sensitizers activate signaling pathways in human dendritic cells leading to DC activation and maturation. Specific objectives are: • To characterize signaling pathways activated in human DCs using the PepChipKinase technology (kinome analysis) in response to chemical sensitizers (Nickel, formaldehyde, dinitrochlorobenzene), chemical irritants (benzalkonium chloride) and danger signals (LPS from e.coli). • To identify if specific signaling pathways are mobilized in response to chemical sensitizers in comparison to irritant molecules using results from kinome analysis. • To identify what are the signals that are missing when comparing chemical haptens to LPS using results from kinome analysis. • To identify what are the initial molecular targets of chemical sensitizers leading to DC activation. Identification of signaling pathways induced by chemical sensitizers, irritant molecules and danger signals. Our first objective is to characterize signaling pathways activated in human DC using the PepChipKinase technology/kinome analysis (Pepscan systems) in response to chemical sensitizers (Nickel, formaldehyde, dinitrochlorobenzene), chemical irritants (benzalkonium chloride) and danger signals (LPS from e.coli). Molecules will be first tested using the maximal sub-toxic concentration (ie the concentration that induced a maximum of 20% cytotoxicity). Two exposure times will be used: 15 min that will allow the identification of kinases activated immediately after chemical addition and 1 hour that corresponds to optimal MAPK and NFkB activation in our DC model. The cellular model will be human DC obtained from cord blood CD34+ progenitors. CD34+ cells will be differentiated in DC using GM-CSF, TNF-alpha, Flt-3l and SCF (stem cell factor) for 6 days. After 6 days, IL-4 is added for 2 days to obtain more CD1a+ cells. This model was selected due to low individual variations as compared to human DC differentiated from monocytes and to the higher yields obtained. The results obtained using this approach will also allow to: •Characterize signal transduction pathways induced by different types of chemical sensitizers in DC. •To identify if specific signaling pathways are mobilized in response to chemical sensitizers in comparison to irritant molecules. •To identify what are the signals that are missing by comparing results obtained with chemical sensitizers to the one using LPS. The next step will be to address the role of the identified kinases in DC activation induced by chemical sensitizers. Previous work performed by our group and others have identified links between DC phenotype alteration by chemical sensitizers and MAPK and NFkB activation. Consequently, MAPK and NFkB activation will be measured after inhibition of identified kinases to understand links between upstream kinases and downstream pathways and the role of these kinases in DC activation. Kinase inhibition will be performed using pharmacological inhibitors if available and specific enough or with promoter-expressed small hairpin RNA (MISSION™ shRNA). Small hairpin RNA (shRNA) are more appropriate than siRNA due to induction of an interferon (IFN) response by siRNA. Finally, DC phenotype (CD83, CD86, CCR7, CD40, IL-12p40) will be evaluated following inhibition of the main kinases identified. Role of Redox imbalance in DC activation by chemical sensitizers. One of the question, still unresolved, is what are the molecular targets mobilized by chemical sensitizers leading to DC activation. We believed that the PepChipKinase approach will help us in this task. However, in parallel we will also work on the role of redox imbalance in DC activation by chemical sensitizers. Oxygen radicals are recognized as signaling molecules and in this respect they act as mediators of cell apoptosis and as regulators of gene expression by their action on redox-regulated transcription factors, like NFKB and AP-1. We will test in our model the hypothesis that alteration in the GSH/GSSG ratio could mediate signaling by haptens in DC through protein S-thiolation/dethiolation with the hypothesis that the primary target protein of glutathione redox is upstream of MAPK and NF-kB. DC will be treated with nickel, DNCB, formaldehyde or benzalkonium chloride and GSH/GSSG ratio will be measured using the GSSG-reductase 5', 5'-dithio-bis(2-nitrobenzoic acid). The effect of GSHet on nickel, formaldehyde or DNCB-induced DC-maturation marker expression (CCR7, CD86, CD83, HLA-DR, CD40, IL-12p40, IL-6) will be tested. The status of the ASK-1/thioredoxin complex will be evaluated by co-immunoprecipitation since ASK-1 is an upstream activator of P38MAPK and JNK and is activated upon release of oxidized thioredoxin from the complex.

Despite the recent advances in the field of silicon photonics, the fabrication of active optical functions and, in particular, the fabrication of lasers remains one of the most difficult tasks. Silicon is an inefficient light emitter because of its indirect bandgap. Until now, except for the approaches that use III-V materials, only the use of a nonlinear effect, the stimulated Raman scattering, has allowed to obtain a laser effect in a rib waveguide etched on a silicon-on-insulator (SOI) substrate. One of the limitations of these reported studies on the stimulated Raman scattering is that they require long cavities (> 1 cm) or high-Q factor ring cavities with large area (~ 1 cm^2) to achieve the gain required by the laser effect. To overcome this limitation, that is incompatible with the on-chip integration of these components, photonic crystals (PhCs) appear as ultra-compact alternatives. The PHLORA project aims at demonstrating continuous wave photonic crystal Raman lasers on SOI with enhanced modulation bandwidth and noise properties compared to classical semiconductor laser diodes in the near infrared range. During this project, we will fabricate the first laser entirely in silicon with dimensions (typically 10 µm by 50 µm) compatible with on-chip large-scale integration. It is expected that the spectral purity of Raman silicon laser is superior to other conventional III-V semiconductor lasers due to the absence of the linewidth enhancement effect resulting from the symmetry of Raman gain spectrum in Si. Moreover, some of the schemes proposed for the reduction of the relative intensity noise (RIN) in the case of fiber Raman lasers can be transposed into very compact ones due to the properties of PhCs. Finally, because photonic crystals are efficient to achieve high quality factor cavities with very small mode volume, i.e. with large spontaneous emission coupling factor b, very large modulation bandwidths are expected for micro-sized Raman laser. Because the Raman gain spectrum in Si is symmetric, no frequency chirping will occur during the modulation of the Raman gain. All these properties make these lasers suitable for direct modulation in high speed telecommunication systems but also for applications like sensing, RF-photonics, metrology, and general research. During the project a particular effort will be put on the modeling of PhC Raman laser. Based on our previous results on the Purcell effect in the case of spontaneous Raman scattering, the model developed during the project will be able to accurately predict the threshold and efficiency of the laser, its noise characteristics and its dynamics properties. From preliminary results, a 10 mW pump power with a quality factor of 10^6 at the Stokes wavelength can be enough to achieve lasing in a cavity made in a W1 photonic crystal waveguide. Hence, we will put the emphasis on the optimization of the quality factor of the cavities, on the reproducibility of the fabricated structures and on the efficient coupling of light in the PhC structures, that are the key points in the successful achievement of a PhC Raman laser. In particular, we expect to demonstrate cavities with quality factors above the 2 millions, present state-of-the-art at IEF. The lasers will be fabricated in both the suspended membrane approach and the silicon on insulator approach, i.e. with the oxide cladding remaining below the photonic crystal, since this approach provides a better mechanical stability and thermal dissipation. One of great strength of this project is that the IEF has all the necessary knowledge and equipment to achieve the whole project: modeling, fabrication and characterization.