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Bellemin-Laponnaz S.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Bellemin-Laponnaz S.,University of Strasbourg | Dagorne S.,CNRS Strasbourg Institute of Chemistry
Chemical Reviews | Year: 2014

Early transition metal N-Heterocyclic carbenes (NHC) complexes in catalysis remain a field to be explored and developed taking advantage of the robustness/stability imparted to the resulting metal-based catalytically active components. Recent and promising reports on the use of early transition metal NHC complexes in homogeneous catalysis include, most notably, their ability to effectively mediate ketone hydrosilylation, olefin/cyclic esters polymerization, and olefin hydroamination reactions. Recent developments in carbene lithium compounds includevthe isolation and structural characterization of Li+ adductsvbearing abnormal NHCs. In related studies on anionic NHCs, Lavallo and co-workers visolated and characterized a number of Li salts of carborane-containing NHC anions starting from a formally monoanionic carborane N-functionalized imidazolium salt as the protio ligand. Other examples of lithium and potassium NHC compounds have been reported and typically include polydentate ligands incorporating a carbene ligand with an anionic functional group and variously functionalized monodentate NHC ligands.

Ganzhorn M.,CNRS Neel Institute | Klyatskaya S.,Karlsruhe Institute of Technology | Ruben M.,Karlsruhe Institute of Technology | Ruben M.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Wernsdorfer W.,CNRS Neel Institute
Nature Nanotechnology | Year: 2013

Magnetic relaxation processes were first discussed for a crystal of paramagnetic transition ions. It was suggested that mechanical vibrations of the crystal lattice (phonons) modulate the crystal electric field of the magnetic ion, thus inducing a 'direct' relaxation between two different spin states. Direct relaxation has also been predicted for single-molecule magnets with a large spin and a high magnetic anisotropy and was first demonstrated in a Mn 12 acetate crystal. The spin-lattice relaxation time for such a direct transition is limited by the phonon density of states at the spin resonance. In a three-dimensional system, such as a single-molecule magnet crystal, the phonon energy spectrum is continuous, but in a one-dimensional system, like a suspended carbon nanotube, the spectrum is discrete and can be engineered to an extremely low density of states. An individual single-molecule magnet, coupled to a suspended carbon nanotube, should therefore exhibit extremely long relaxation times and the system's reduced size should result in a strong spin-phonon coupling. Here, we provide the first experimental evidence for a strong spin-phonon coupling between a single molecule spin and a carbon nanotube resonator, ultimately enabling coherent spin manipulation and quantum entanglement. © 2013 Macmillan Publishers Limited. All rights reserved.

Banhart F.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Kotakoski J.,University of Helsinki | Krasheninnikov A.V.,University of Helsinki | Krasheninnikov A.V.,Aalto University
ACS Nano | Year: 2011

Graphene is one of the most promising materials in nanotechnology. The electronic and mechanical properties of graphene samples with high perfection of the atomic lattice are outstanding, but structural defects, which may appear during growth or processing, deteriorate the performance of graphenebaseddevices. However, deviations from perfection can be useful in some applications, as they make it possible to tailor the local properties of graphene and to achieve new functionalities. In this article, the present knowledge about point and line defects in graphene are reviewed. Particular emphasis is put on the unique ability of graphene to reconstruct its lattice around intrinsic defects, leading to interesting effects and potential applications. Extrinsic defects such as foreign atoms which are of equally high importance for designing graphene-based devices with dedicated properties are also discussed. © 2011 American Chemical Society.

Genschik P.,Institute Of Biologie Moleculaire Des Plantes | Sumara I.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Lechner E.,Institute Of Biologie Moleculaire Des Plantes
EMBO Journal | Year: 2013

Protein ubiquitylation is a post-translational modification that controls all aspects of eukaryotic cell functionality, and its defective regulation is manifested in various human diseases. The ubiquitylation process requires a set of enzymes, of which the ubiquitin ligases (E3s) are the substrate recognition components. Modular CULLIN-RING ubiquitin ligases (CRLs) are the most prevalent class of E3s, comprising hundreds of distinct CRL complexes with the potential to recruit as many and even more protein substrates. Best understood at both structural and functional levels are CRL1 or SCF (SKP1/CUL1/F-box protein) complexes, representing the founding member of this class of multimeric E3s. Another CRL subfamily, called CRL3, is composed of the molecular scaffold CULLIN3 and the RING protein RBX1, in combination with one of numerous BTB domain proteins acting as substrate adaptors. Recent work has firmly established CRL3s as major regulators of different cellular and developmental processes as well as stress responses in both metazoans and higher plants. In humans, functional alterations of CRL3s have been associated with various pathologies, including metabolic disorders, muscle, and nerve degeneration, as well as cancer. In this review, we summarize recent discoveries on the function of CRL3s in both metazoans and plants, and discuss their mode of regulation and specificities. © 2013 European Molecular Biology Organization.

Banhart F.,CNRS Institute of Genetics and of Molecular and Cellular Biology
Beilstein Journal of Nanotechnology | Year: 2015

Linear strings of Sp1-hybridized carbon atoms are considered as a possible phase of carbon since decades. Whereas the debate about the stability of the corresponding bulk phase carbyne continues until today, the existence of isolated chains of carbon atoms has meanwhile been corroborated experimentally. Since graphene, as the two-dimensional Sp2-bonded allotrope of carbon, has become a vast field, the question about the importance of one-dimensional carbon became of renewed interest. The present article gives an overview of the work that has been carried out on chains of carbon atoms in the past one or two decades. The review concentrates on isolated chains of carbon atoms and summarizes the experimental observations to date. While the experimental information is still very limited, many calculations of the physical and chemical properties have been published in the past years. Some of the most important theoretical studies and their importance in the present experimental situation are reviewed. © 2015 Banhart licensee Beilstein-Institut.

Carrado A.,CNRS Institute of Genetics and of Molecular and Cellular Biology
ACS Applied Materials and Interfaces | Year: 2010

Plasma-spray (PS) is a classical technique usually employed to cover orthopaedic titanium implant surfaces with hydroxyapatite (HA - Ca10(PO 4) 6(OH) 2). The objective of the current study is to investigate the structure and microstructure of HA plasma-spray 50 μm thick coating on titanium alloy (Ti-6Al-4 V) and residual stress due to processing in the substrate and in HA coating. The structure of the coatings was determined by high-energy synchrotron X-ray diffraction in energy dispersive (HESXRD), selected area electron diffraction (saed), Scanning Electron Microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). No impurity phases in the HA were identified by HESXRD to keep away from the decomposition of HA at high temperature. hcp phase of HA substrate was detected with slight amorphous background. FTIR spectrum of a HA powder shows a typical spectrum for HA material with the characteristic phosphate peaks for HA at wavenumbers of 1090, 1052, 963, 602, and 573 cm -1 are present. The morphology of HA powder observed by SEM exhibits grains of ca. 0.1 μmwell-adapted for cell proliferation. HA/Ti-6Al-4 V interface observed by cross-section scanning and transmission electronmicroscopy (TEM) presentsmicrocracks. Residual stresses were analyzed by sin 2 ψ X-ray diffraction method on titanium substrates and HA coating. Although the Ti substrates are in a slightly tensile residual state, the coated ones show a compressive state. © 2010 American Chemical Society.

Sexton T.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Cavalli G.,Institute of Human Genetics IGH
Cell | Year: 2015

The genome must be highly compacted to fit within eukaryotic nuclei but must be accessible to the transcriptional machinery to allow appropriate expression of genes in different cell types and throughout developmental pathways. A growing body of work has shown that the genome, analogously to proteins, forms an ordered, hierarchical structure that closely correlates and may even be causally linked with regulation of functions such as transcription. This review describes our current understanding of how these functional genomic "secondary and tertiary structures" form a blueprint for global nuclear architecture and the potential they hold for understanding and manipulating genomic regulation. © 2015 Elsevier Inc.

Bailleul M.,CNRS Institute of Genetics and of Molecular and Cellular Biology
Applied Physics Letters | Year: 2013

We show that the propagation of microwave fields along a planar transmission line is strongly modified when a conducting film is brought close to it. The effect is attributed to the shielding of the electrical and/or magnetic microwave fields which is shown to occur over a wide range of parameters (microwave frequency, film square resistance, transverse dimensions of the waveguide). This is illustrated by finite-element electromagnetic simulations and interpreted using a distributed impedance model. We discuss the implications of this phenomenon for broadband measurements of ferromagnetic resonance realized by placing a ferromagnetic metal film above a coplanar waveguide. © 2013 AIP Publishing LLC.

Stoeffler D.,CNRS Institute of Genetics and of Molecular and Cellular Biology
Journal of Physics Condensed Matter | Year: 2012

The electric polarization in the multiferroic GaFeO 3 system is determined from its electronic structure using first principles methods and the modern theory of polarization. By carefully following the electric polarization on a path connecting the polar and centrosymmetric structures, it is found to be 25μCcm 2, which is ten times larger than a previous estimation given in the literature a few years ago and two times smaller than the value obtained in a recent similar study. The switching of this electric polarization through a centrosymmetric structure is discussed in terms of the total energy barrier. It is exhibited that such a switching is particularly difficult to achieve in relation to the tetrahedral environment of half of the Ga atoms. The switching via domain wall motion is also discussed. © 2012 IOP Publishing Ltd.

Manfredi G.,CNRS Institute of Genetics and of Molecular and Cellular Biology
European Journal of Physics | Year: 2013

In 1973, Le Bellac and Lévy-Leblond (Nuovo Cimento B 14 217-234) discovered that Maxwell's equations possess two non-relativistic Galilei-covariant limits, corresponding to |E| ≫ c|B| (electric limit) or |E| ≪ c|B| (magnetic limit). Here, we provide a systematic, yet simple, derivation of these two limits based on a dimensionless form of Maxwell's equations and an expansion of the electric and magnetic fields in a power series of some small parameters. Using this procedure, all previously known results are recovered in a natural and unambiguous way. Some further extensions are also proposed. © 2013 IOP Publishing Ltd.

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