110 research outputs found
Historical Lyonaise brace treatment for adolescent hyperkyphosis. Results of 272 cases reviewed 2 years minimum after removal of the brace
TiC-carbide derived carbon electrolyte adsorption study by ways of X-ray scattering analysis
Understanding ion adsorption in nanoporous
carbon electrodes is of great importance for designing the
next-generation of high energy density electrical doublelayer
capacitors. In this work, X-ray scattering is used for
investigating the impregnation of nanoporous carbons with
electrolytes in the absence of applied potential. We are able
to show that interactions between the carbon surface and
electrolytes allow adsorption to take place in sub-nanopores,
thus confirming experimentally for the first time the
results predicted by molecular dynamic simulations
Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes
[EN] The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy center dot(NCN)-N-(Ar); L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H-2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.The authors thank CNRS, UPS-Toulouse, INSA, "IDEX/Chaires d'attractivite l'Universite Federale Toulouse Midi-Pyrenees", "Instituto de Tecnologia Quimica" (ITQ; UPV-CSIC), "Juan de la Cierva" programme (IJCI-2016-27966), "Primero Proyectos de Investigacion" (PAID-06-18), "Instituto de Investigaciones Quimicas" (IIQ; CSIC-US), "Ministerio de Ciencia, Innovacion y Universidades" (MCIU/AEI), FEDER funds of the European Union (PGC2018-095768-B-I00) and ERC Advanced Grant (MONACAT 2015-694159) for financial support. We also thank L. Datas for the TEM facilities (UMS Castaing) and S. Cayez for the HRTEM measurements.LĂłpez-Vinasco, AM.; MartĂnez-Prieto, LM.; Asensio, JM.; Lecante, P.; Chaudret, B.; CĂĄmpora, J.; Van Leeuwen, PWNM. (2020). Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes. Catalysis Science & Technology. 10(2):342-350. https://doi.org/10.1039/c9cy02172hS342350102Swamy, K. C. K., Reddy, A. S., Sandeep, K., & Kalyani, A. (2018). Advances in chemoselective and/or stereoselective semihydrogenation of alkynes. Tetrahedron Letters, 59(5), 419-429. doi:10.1016/j.tetlet.2017.12.057Lei, J., Su, L., Zeng, K., Chen, T., Qiu, R., Zhou, Y., ⊠Yin, S.-F. (2017). Recent advances of catalytic processes on the transformation of alkynes into functional compounds. Chemical Engineering Science, 171, 404-425. doi:10.1016/j.ces.2017.05.021J. G. de Vries and C. 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Promotion Effect of Alkali Metal Hydroxides on Polymer-Stabilized Pd Nanoparticles for Selective Hydrogenation of CâC Triple Bonds in Alkynols. Industrial & Engineering Chemistry Research, 56(45), 13219-13227. doi:10.1021/acs.iecr.7b01612Reina, A., Favier, I., Pradel, C., & GĂłmez, M. (2018). Stable Zero-Valent Nickel Nanoparticles in Glycerol: Synthesis and Applications in Selective Hydrogenations. Advanced Synthesis & Catalysis, 360(18), 3544-3552. doi:10.1002/adsc.201800786De los Bernardos, M. D., PĂ©rez-RodrĂguez, S., Gual, A., Claver, C., & Godard, C. (2017). Facile synthesis of NHC-stabilized Ni nanoparticles and their catalytic application in the Z-selective hydrogenation of alkynes. Chemical Communications, 53(56), 7894-7897. doi:10.1039/c7cc01779kWen, X., Shi, X., Qiao, X., Wu, Z., & Bai, G. (2017). Ligand-free nickel-catalyzed semihydrogenation of alkynes with sodium borohydride: a highly efficient and selective process for cis-alkenes under ambient conditions. Chemical Communications, 53(39), 5372-5375. doi:10.1039/c7cc02140bKonnerth, H., & Prechtl, M. H. G. (2016). Selective partial hydrogenation of alkynes to (Z)-alkenes with ionic liquid-doped nickel nanocatalysts at near ambient conditions. Chemical Communications, 52(58), 9129-9132. doi:10.1039/c6cc00499gCarenco, S., Leyva-PĂ©rez, A., ConcepciĂłn, P., BoissiĂšre, C., MĂ©zailles, N., Sanchez, C., & Corma, A. (2012). Nickel phosphide nanocatalysts for the chemoselective hydrogenation of alkynes. Nano Today, 7(1), 21-28. doi:10.1016/j.nantod.2011.12.003Polshettiwar, V., Baruwati, B., & Varma, R. S. (2009). Nanoparticle-supported and magnetically recoverable nickel catalyst: a robust and economic hydrogenation and transfer hydrogenation protocol. Green Chem., 11(1), 127-131. doi:10.1039/b815058cAlonso, F., Osante, I., & Yus, M. (2007). Highly selective hydrogenation of multiple carbonâcarbon bonds promoted by nickel(0) nanoparticles. 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3D Ruthenium Nanoparticle Covalent Assemblies from Polymantane Ligands for Confined Catalysis
The synthesis of metal nanoparticle (NP) assemblies stabilized by functional molecules is an important research topic in nanoscience, and the ability to control interparticle distances and positions in NP assemblies is one of the major challenges in designing and understanding functional nanostructures. Here, two series of functionalized adamantanes, bis-adamantanes, and diamantanes, bearing carboxylic acid or amine functional groups, were used as building blocks to produce, via a straightforward method, networks of ruthenium NPs. Both the nature of the ligand and the Ru/ligand ratio affect the interparticle distance in the assemblies. The use of 1,3-adamantanedicarboxylic acid allows the synthesis of three-dimensional (3D) networks of 1.7â1.9 nm Ru NPs presenting an interparticle distance of 2.5â2.7 nm. The surface interaction between Ru NPs and the ligands was investigated spectroscopically using a 13C-labeled ligand, as well as theoretically with density functional theory (DFT) calculations. We found that Ru species formed during the NP assembly are able to partially decarbonylate carboxylic acid ligands at room temperature. Decarbonylation of a carboxylic acid at room temperature in the presence of dihydrogen usually occurs on catalysts at much higher temperatures and pressures. This result reveals a very high reactivity of ruthenium species formed during the network assembly. The Ru NP networks were found to be active catalysts for the selective hydrogenation of phenylacetylene, reaching good selectivity toward styrene. Overall, we demonstrated that catalyst activity, selectivity, and NP network stability are significantly affected by Ru NP interparticle distance and electronic ligand effects. As such, these materials constitute a unique set that should allow a better understanding of the complex surface chemistry in carbon-supported metal catalysts
2D and 3D Ruthenium Nanoparticle Covalent Assemblies for Phenyl Acetylene Hydrogenation
The bottomâup covalent assembly of metallic nanoparticles (NP) represents one of the innovative tools in nanotechnology to build functional heterostructures, with the resulting assemblies showing superior collective properties over the individual NP for a broad range of applications. The ability to control the dimensionality of the assembly is one of the major challenges in designing and understanding these advanced materials. Here, two new organic linkers were used as building blocks in order to guide the organization of Ru NP into twoâ or threeâdimensional covalent assemblies. The use of a hexaâadduct functionalized C60 leads to the formation of 3D networks of 2.2 nm Ru NP presenting an interparticle distance of 3.0 nm, and the use of a planar carboxylic acid triphenylene derivative allows the synthesis of 2D networks of 1.9 nm Ru NP with an interparticle distance of 3.1 nm. The Ru NP networks were found to be active catalysts for the selective hydrogenation of phenylacetylene, reaching good selectivity toward styrene. Overall, we demonstrated that catalyst performances are significantly affected by the dimensionality (2D vs. 3D) of the heterostructures, which can be rationalize based on confinement effects
Ultrasmall manganese ferrites for in vivo catalase mimicking activity and multimodal bioimaging
Manganese ferrite nanoparticles display interesting features in bioimaging and catalytic therapies. They have been recently used in theranostics as contrast agents in magnetic resonance imaging (MRI), and as catalase-mimicking nanozymes for hypoxia alleviation. These promising applications encourage the development of novel synthetic procedures to enhance the bioimaging and catalytic properties of these nanomaterials simultaneously. Herein, a cost-efficient synthetic microwave method is developed to manufacture ultrasmall manganese ferrite nanoparticles as advanced multimodal contrast agents in MRI and positron emission tomography (PET), and improved nanozymes. Such a synthetic method allows doping ferrites with Mn in a wide stoichiometric range (MnxFe3-xO4, 0.1 †x †2.4), affording a library of nanoparticles with different magnetic relaxivities and catalytic properties. These tuned magnetic properties give rise to either positive or dual-mode MRI contrast agents. On the other hand, higher levels of Mn doping enhance the catalytic efficiency of the resulting nanozymes. Finally, through their intracellular catalase-mimicking activity, these ultrasmall manganese ferrite nanoparticles induce an unprecedented tumor growth inhibition in a breast cancer murine model. All of these results show the robust characteristics of these nanoparticles for nanobiotechnological applications.The authors thank M. Jeannin from Lasie Laboratory (La Rochelle University) for the Raman studies. S.C.R. is supported by the grant PID2019-106139RA-100 funded by MCIN. J.R.-C. is supported by grants from the Ministerio de EconomĂa, Industria y Competitividad (MEIC) (SAF2017-84494-C2-R). J.R.C. received funding from the BBVA Foundation (PR [18]_BIO_IMG_0008) and La Caixa (HR18-00052). Y.F.-A. received funding from the Santander-Universidad Zaragoza Fellowship program. L.G. acknowledges financial support from the RamĂłn y Cajal program (RYC-2014-15512). CIC biomaGUNE is supported by the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency (MDM-2017-0720). The authors acknowledge the use of Servicio General de Apoyo a la InvestigaciĂłn-SAI, Universidad de Zaragoza. H.G. is supported by the Ligue contre le Cancer (CD16, CD17) and RĂ©gion Nouvelle Aquitaine (Projet âNanovectâ). J.A.E. is supported by RTI2018-099357-B-I00, HFSP (RGP0016/2018), CIBERFES16/10/00282 and RED2018-102576-T. The CNIC is supported by the Pro-CNIC Foundation and by the Severo Ochoa of Excellence Program.Peer reviewe
Inventive Intellectual Corpus Analysis Applied to Incremental Technological Innovation
International audienceOur concern deals with the Knowledge Based Innovation domain in an industrial context. When a creative idea is generated, its transformation into new knowledge depends on a cycle associating three subsystems and highlighting the link between idea and knowledge: the individual who generated the idea, the knowledge field which acts as a reference repository and the knowledge community who evaluates, selects and validates relevant ideas. Usual innovation dynamic is based on creative problem solving (from problem to solution). This paper covers the reversibility of the link idea-knowledge, that is to say the passage from knowledge to inventive idea. We promote an ab nihilo innovation dynamic (from ideation to innovation). In this paper, we propose an inventive idea generation method which takes advantage of the inventive intellectual Corpus of Knowledge actors. The research is dedicated to the epistemic connection between the structural analysis of knowledge contained in inventive intellectual Corpus and the ideation seen as inventive knowledge generation. Our methodology consists in building a theoretical representative model and in validating it through experimentation. Model's input data represent a cognitive stimulus and model's output data consist of a prospective vision. Cognitive stimulus is based on in-depth analysis of the texture of knowledge structuring the inventive intellectual Corpus. Results include experimental validation of the Knowledge Based Innovation approach. Our contribution consists in showing that ideation, stimulated by the critical analysis of the structure of knowledge lying in the knowledge actor's inventive intellectual Corpus, can be seen as an epistemic mutation, where source, process, results, corpus and knowledge actor can be assimilated as an unique entity. An illustration of possible software implementation is given, derived from existing KM extraction software suite
SynthÚse et caractérisation de nanoparticules métalliques (application à l'élaboration de nanocomposites)
TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF
Extraction de polysaccharides issus d'algues rouges (optimisation des procédés, études physico-chimiques et approches industrielles)
Dans le cadre d une collaboration industrielle, l objectif principal de cette étude a été de mettre au point des texturants à partir de différentes algues rouges. En premier, nous avons développé des procédés de fabrication de carraghénanes semi-raffinés à partir des algues Kappaphycus alvarezii, Kappaphycus striatum et Eucheuma denticulatum. Par ailleurs, les [iota]- et [kappa]-carraghénanes et leurs précurseurs respectifs ont été caractérisés par spectroscopie RMN. Les [iota]- et [kappa]-carraghénanes ont été caractérisés par spectroscopie infrarouge ainsi que le [lambda]-carraghénane extrait des algues Gigartina skottsbergii. Par la suite, nous avons étudié les effets des conditions de traitement alcalin des algues Gracilaria verrucosa et Gelidium sesquipedale sur la qualité de l agar. Nous nous sommes également intéressés à différents traitements acides afin d améliorer à la fois le rendement et la qualité de l agar. Un procédé de blanchiment des algues Gracilaria verrucosa a été développé. Enfin, la désulfatation de l agar sur résines anioniques a été abordée.AIX-MARSEILLE3-BU Sc.St JérÎ (130552102) / SudocSudocFranceF
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