Marc Petit

Surface modification using phosphonic acids and esters.

Cleḿence Queffeĺec,† Marc Petit,†,‡ Pascal Janvier,† D. Andrew Knight, and Bruno Bujoli*,† †LUNAM Universite,́ CNRS, UMR 6230, Chimie Et Interdisciplinarite:́ Synthes̀e Analyse Modeĺisation (CEISAM), UFR Sciences et Techniques, 2, rue de la Houssinier̀e, BP 92208, 44322 NANTES Cedex 3, France ‡Universite ́ Pierre et Marie Curie (UPMC), CNRS, UMR7201, Institut Parisien De Chimie Molećulaire (IPCM), 4 place Jussieu, 75252 Paris Cedex 05, France Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901, United States

Towards Zirconium Phosphonate-Based Microarrays for Probing DNA−Protein Interactions: Critical Influence of the Location of the Probe Anchoring Groups

Terminal phosphate groups on double-stranded DNA probes bind strongly to glass substrates coated with a zirconium phosphonate monolayer, and probes immobilized in this way as microarrays can be used to detect protein targets. The sensitivity of the microarray was shown to be enhanced by the use of a polyguanine segment ((G)n , n > or = 5) as a spacer between the phosphate linker and the protein interaction domain. More importantly, the presence of phosphate linkers on both ends of the dsDNA probes leads to significant enhancement of target capture. The relevant characteristics of the different probes when bound to the surface were determined, by the original use of a combination of surface characterization techniques (XPS, AFM, and Sarfus). In this context, the location of the phosphate linkers in the duplex probes was found to result in different probe surface coverage and presentation on the surface, which affect subsequent interactions with the target protein.

C-H activation/functionalization catalyzed by simple, well-defined low-valent cobalt complexes.

A facile C-H activation and functionalization of aromatic imines is presented using low-valent cobalt catalysts. Using Co(PMe3)4 as catalyst we have developed an efficient and simple protocol for the C-H/hydroarylation of alkynes with an anti selectivity. Deuterium-labeling experiments, DFT calculations coupled with the use of a well-defined catalyst have for the first time shed light on the elusive black box of cobalt catalyzed C-H functionalization.

A methodology to design a fuzzy logic based supervision of Hybrid Renewable Energy Systems

Hybrid Renewable Energy Systems (HRES) are increasingly used to improve the grid integration of wind power generators. The goal of this work is to propose a methodology to design a fuzzy logic based supervision of this new kind of production unit. A graphical modeling tool is proposed to facilitate the analysis and the determination of fuzzy control algorithms adapted to complex hybrid systems. To explain this methodology, the association of wind generators, decentralized generators and storage systems are considered for the production of electrical power. The methodology is divided in six steps covering the design of a supervisor from the system work specifications to an optimized implementation of the control. The performance of this supervisor is shown with the help of simulations. Finally, the application of this methodology to the supervision of different topologies of HRES is also proposed to bring forward the systematic dimension of the approach.

Bisphosphonate adaptors for specific protein binding on zirconium phosphonate-based microarrays.

Two bisphosphonate adaptors were designed to immobilize histidine-tagged proteins onto glass substrates coated with a zirconium phosphonate monolayer, allowing efficient and oriented immobilization of capture proteins, affitins directed to lysozyme, on a microarray format. These bifunctional adaptors contain two phosphonic acid anchors at one extremity and either one nitrilotriacetic acid (NTA) or two NTA groups at the other. The phosphonate groups provide a stable bond to the zirconium interface by multipoint attachment and allow high density of surface coverage of the linkers as revealed by X-ray photoelectron spectroscopy (XPS). Reversible high-density capture of histidine-tagged proteins is shown by real-time surface plasmon resonance enhanced ellipsometry and in a microarray format using fluorescence detection of AlexaFluor 647-labeled target protein. The detection sensitivity of the microarray for the target protein was below 1 nM, despite the monolayer arrangement of the probes, due to very low background staining, which allows high fluorescent signal-to-noise ratio. The performance of these Ni-NTA-modified zirconium phosphonate coated slides compared favorably to other types of microarray substrates, including slides with a nitrocellulose-based matrix, epoxide slides, and epoxide slides functionalized with Ni-NTA groups. This immobilization strategy has a large potential to fix any histidine-tagged proteins on zirconium or titanium ion surfaces.

The in vivo degradation of a ruthenium labelled polysaccharide-based hydrogel for bone tissue engineering.

In this paper we report a new method that permitted for the first time to selectively track a polysaccharide-based hydrogel on bone tissue explants, several weeks after its implantation. The hydrogel, which was developed for bone healing and tissue engineering, was labelled with a ruthenium complex and implanted into rabbit bone defects in order to investigate its in vivo degradation. 1, 2, 3 and 8 weeks after surgery, the bone explants were analyzed by synchrotron X-ray microfluorescence, infrared mapping spectroscopy, scanning electron microscopy, and optical microscopy after histological coloration. The results showed that the labelled polysaccharide-based hydrogel was likely to undergo phagocytosis that seemed to occur from the edge to the center of the implantation site up to at least the 8th week.

Demand side management of electrical water heaters and evaluation of the Cold Load Pick-Up characteristics (CLPU)

Cold Load Pickup (CLPU) is the temporary load increase observed at load reconnection following disconnection of inertia loads such as groups of heaters, air conditioners, and so forth. This paper presents an analysis of the CLPU when Demand Response actions are applied to electrical water heaters. The analysis is compared with the analysis of other authors. Different control strategies are then proposed to reduce the CLPU amplitude and its impact on the power system around the DR application period. The final objective is to use Demand Response as a controllable regulation mean to be applied to the various grid ancillary services.

Cobalt-mediated cyclotrimerization and cycloisomerization reactions. Synthetic applications

This article reviews our contribution in the field of the cobalt(I)-mediated cycliza- tions. The use of new unsaturated partners such as allenes extend the scope and the utility of the previously developed intramolecular (2a2a2) cyclotrimerization. The presence of chiral auxiliaries induced high level of diastereoselectivity in the enediynes cyclization. The discovery of cobalt(I) catalyzed ene-type reaction allows to propose an efficient route to the basic skeleton of tetracyclic diterpenes via a one-pot sequence of cyclizations: (ene-type)/ (2a2a2)/(4a2). This cascade created six carbon-carbon bonds, four rings in a totally stereoselective manner. Finally, a new strategy to the taxoids is proposed.

C2-Alkylation and Alkenylation of Indoles Catalyzed by a Low-Valent Cobalt Complex in the Absence of Reductant

Herein an extremely versatile, well-defined, low-valent cobalt catalyst [Co(PMe3)4] capable of intermolecular and intramolecular imine-directed C2-alkylation and alkenylation of indoles is reported. The reaction proceeds in the absence of reducing agents or additives, affording a range of substituted indoles and dihydropyrroloindoles in high yields and regioselectivities. With the aid of deuterium labeling studies and DFT (Density Functional Theory) calculations, a mechanism is proposed that is based on a Ligand-to-Ligand Hydrogen Transfer pathway.

Regio- and Stereoselective Hydrosilylation of Unsymmetrical Alkynes Catalyzed by a Well-Defined, Low-Valent Cobalt Catalyst.

Herein, the use of a well-defined low-valent cobalt(I) catalyst [HCo(PMe3)4] capable of performing the highly regio- and stereoselective hydrosilylation of internal alkynes is reported. The reaction can be applied to a variety of hydrosilanes, symmetrical and unsymmetrical alkynes, giving in many cases a single hydrosilylation isomer. Experimental and theoretical studies suggest the key step to be a hydro-cobaltation and that the reaction proceeds through a classical Chalk-Harrod mechanism.