Search

Your search keyword '"Didierjean J"' showing total 101 results
Start Over Author "Didierjean J"
101 results on '"Didierjean J"'

9. Single-crystal Yb:YAG fiber amplifiers for fs sources (Oral)

Author

Georges , Patrick, Lesparre , Fabien, Gomes , Jean-Thomas, Délen , Xavier, Martial , Igor, Didierjean , J, Druon , Frédéric, Balembois , François, Laboratoire Charles Fabry / Lasers, Laboratoire Charles Fabry ( LCF ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut d'Optique Graduate School ( IOGS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Sud - Paris 11 ( UP11 ) -Institut d'Optique Graduate School ( IOGS ) -Centre National de la Recherche Scientifique ( CNRS ), Fibercryst, Laboratoire Charles Fabry (LCF), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [ PHYS.PHYS.PHYS-OPTICS ] Physics [physics]/Physics [physics]/Optics [physics.optics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

11. High power single crystal fiber amplifiers for linearly and cylindrically polarized picosecond lasers (Orale)

Author

Lesparre, Fabien, Gomes, J.-T, Delen, Xavier, Martial, Igor, Didierjean, J, Pallmann, Wolfgang, Resan, B, Eckerle, Michael, Graf, T., Abdou Ahmed, M., Druon, Frédéric, Balembois, François, Georges, Patrick, Fibercryst, Laboratoire Charles Fabry / Lasers, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS), JDSU Laser Products, Institut für Strahwerkzeuge (IFSW), Stuttgart University, and Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

12. High power (100 W) Yb:YAG single-crystal fiber amplification chain for sub-ps MHz system(Orale)

Author

Lesparre, Fabien, Gomes, J.-T, Martial, I, Delen, Xavier, Didierjean, J, Resan, B, Loscher, A, Negel, J.-P, Graf, T, Abdou, M, Balembois, François, Georges, Patrick, Fibercryst, Laboratoire Charles Fabry / Lasers, Laboratoire Charles Fabry ( LCF ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut d'Optique Graduate School ( IOGS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Sud - Paris 11 ( UP11 ) -Institut d'Optique Graduate School ( IOGS ) -Centre National de la Recherche Scientifique ( CNRS ), JDSU Laser Products, Institut für Strahwerkzeuge ( IFSW ), Stuttgart University, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Institut für Strahwerkzeuge (IFSW), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [ PHYS.PHYS.PHYS-OPTICS ] Physics [physics]/Physics [physics]/Optics [physics.optics]
Abstract

International audience; Since few years, the single-crystal fiber (SCF) technology has demonstrated very interesting features, combining the advantages of bulk crystals and glass fibers. Thanks to a very efficient thermal management and a high overlap between the guided pump and the unguided signal, SCF technology is well suited with the requirement of Master Oscillator Power Amplifier (MOPA) dedicated to high average power pulsed laser [1]. Recently, 30 W average power at 380 fs pulse duration has been demonstrated using a single SCF amplification stage [2]. In the frame of the European project " Ultrafast RAZipol " , we present in this paper a MOPA setup using three successive SCF amplification stages to reach an average power up to 100 W at sub-picosecond pulse duration and 20 MHz repetition rate. The seed laser is a passively-modelocked Yb-based laser delivering 356 fs / 20 MHz / 1,5 W / 1031 nm. The first stage consists of an Yb:YAG SCF (2% at., 1 mm diameter, 30 mm long) in a double-pass configuration pumped by a high brightness fiber-coupled laser diode (core diameter 100 µm, NA=0,22) emiting 120 W at 940 nm. The second amplifier is based on a simple pass through an Yb:YAG SCF (1% at., 1 mm diameter, 40 mm long) pumped by a wavelength stabilized 200 W fiber-coupled laser diode at 969 nm (core diameter 200 µm, NA=0,22) to reduce thermal load in the crystal. The output power reaches 65.5 W. The third stage uses an Yb:YAG SCF (1% at., 1 mm diameter, 30 mm long) in simple pass configuration pumped by a 120 W fiber-coupled laser diode at 940 nm (core diameter 100 µm, NA=0,22) to finally reach an average power of 100 W.

Published
2015

14. Study of a new class of HIV-1 reverse transcriptase and integrase inhibitors

Author

Didierjean, J., Architecture et réactivité de l'ARN (ARN), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Université Louis Pasteur - Strasbourg I, Roland Marquet.(R.Marquet@ibmc.u-strasbg.fr), and Martin, Isabelle

Subjects
Intégrase, Rétrotranscriptase, Inhibition, VIH, ?-hydroxytropolones, Mg2+, [SDV.BBM.BC] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Rétrovirus, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM]
Abstract

(english text not available), L'Organisation Mondiale de la Santé estime que le VIH-1 est porté par 40 millions de personnes à travers le monde, et qu'il a causé 3,1 millions de décès et 4,9 millions de nouvelles infections au cours de l'année 2004. Les traitements actuels ciblent principalement la rétrotranscriptase du VIH-1 (RT), qui catalyse le passage de l'ARN viral génomique en ADN double brin, substrat de l'intégrase virale (IN). Les antiviraux dirigés contre la RT et utilisés en thérapie sont soit des terminateurs de chaîne analogues de nucléosides (NRTIs), soit des inhibiteurs non-nucléosidiques (NNRTIs) qui se fixent au niveau d'une poche hydrophobe, à proximité du site de fixation des nucléotides. Dans le cadre du développement de nouveaux inhibiteurs de la RT, nous nous sommes intéressés aux 3,7-dihydroxytropolones (3,7-DHT), qui inhibent l'inositol monophosphatase humaine par chélation de deux ions Mg2+ catalytiques distants de 3,7Å. Or les sites catalytiques polymérase et RNase H de la RT contiennent respectivement deux ions Mg2+ distants de 3,57 et 4Å. En outre, l'IN du VIH-1 possède une plate-forme catalytique proche de celle du site RNase H. Nous avons ainsi entrepris d'étudier l'effet des 3,7-DHT sur les activités de la RT et de l'IN du VIH-1. Nous avons observé une inhibition spécifique de l'une ou l'autre activité de la RT par certaines 3,7-DHT. Des études enzymatiques ont ensuite montré que l'inhibition de l'activité ADN polymérase est non-compétitive vis-à-vis des nucléotides, à l'instar des NNRTIs. Néanmoins, l'étude de RT résistante ou dépourvue du site de fixation des NNRTIs permet d'exclure un mode d'action identique à cette classe d'inhibiteurs. Des expériences de gel-filtration, permettant de suivre l'état d'oligomérisation de la forme active de la RT, hétérodimérique, montrent que les 3,7-DHT ne sont pas capables de la dissocier. L'inhibition des activités de la RT par liaison des 3,7-DHT aux acides nucléiques a été écartée, entre autres, par des expériences de fluorescence. Enfin nous avons montré que les 3,7-DHT n'inhibent pas la polymérisation lors de l'étape de translocation. En revanche, une forte baisse de l'inhibition de la synthèse d'ADN a été mise en évidence lorsque la concentration en Mg2+ diminue, ce qui suggère que les 3,7-DHT ne lient le site actif polymérase qu'en présence des ions Mg2+. L'implication des cations catalytiques dans les mécanismes d'inhibition par les 3,7-DHT a également été étayée par l'observation d'une inhibition des activités de « processing » et de transfert de l'IN, dépendante du cation utilisé.Malheureusement, des cultures cellulaires en présence de 3,7-DHT ont révélé une cytotoxicité importante. Ce résultat était partiellement prévisible, compte tenu de l'existence de nombreuses enzymes bimétalliques cellulaires et de l'utilisation de 3,7-DHT de première génération. Dans l'objectif d'améliorer ces composés, sur la base de leur relation structure/activité, nous avions également pour projet d'obtenir la structure cristallographique d'un complexe ternaire RT/(matrice/amorce)/dNTP, en présence d'une 3,7-DHT. Des cristaux de différents complexes ont été obtenus, mais n'ont pas permis d'obtenir de clichés de diffraction aux rayons X et restent par conséquent à améliorer. Nous avons également étudié l'influence de la concentration en Mg2+ libre sur les activités catalytiques de la RT du VIH-1.En résumé, les résultats obtenus au cours de mon travail de thèse permettent d'élaborer les prémices d'une stratégie de conception « rationalisée » d'inhibiteurs de la RT et de l'IN, dans l'objectif d'obtenir des composés plus spécifiques et plus affins de l'un ou l'autre site catalytique.

Published
2005

30. Diode pumping of Yb3+:CaGdAlO 4

Author

Petit, P. O., primary, Goldner, P., additional, Viana, B., additional, Boudeile, J., additional, Didierjean, J., additional, Balembois, F., additional, Druon, F., additional, and Georges, P., additional

Published
2008
Full Text
View/download PDF

35. Diode-pumped Yb:CaGdAlO4 femtosecond laser

Author

Zaouter, Y., primary, Didierjean, J., additional, Lucas-Leclin, G., additional, Balembois, F., additional, Druon, F., additional, Georges, P., additional, Petit, J., additional, Goldner, P., additional, and Viana, B., additional

Published
2006
Full Text
View/download PDF

36. 47-fs diode-pumped Yb^3+:CaGdAlO_4 laser

Author

Zaouter, Y., primary, Didierjean, J., additional, Balembois, F., additional, Leclin, G. Lucas, additional, Druon, F., additional, Georges, P., additional, Petit, J., additional, Goldner, P., additional, and Viana, B., additional

Published
2006
Full Text
View/download PDF

39. Synthesis of Enantiopure 4-Hydroxypipecolate and 4-Hydroxylysine Derivatives from a Common 4,6-Dioxopiperidinecarboxylate Precursor.

Author

Marin, J., C. Didierjean, J., Aubry, A., Casimir, J.-R., Briand, J.-P., and Guichard, G.

Subjects
*LACTAMS, *AMIDES, *HETEROCYCLIC compounds, *LYSINE, *AMINO acids, *ORGANIC acids
Abstract

tert-Butyl 2-substituted 4,6-dioxo-1-piperidinecarboxylates 4 have been prepared in good yield starting from Boc-Asp-O[sup t]Bu and other β-amino acids. By analogy with chiral tetramic acids, their reduction by NaBH[sub 4] in CH[sub 2]Cl[sub 2]/AcOH afforded the corresponding cis-4-hydroxy δ-lactams in good yield and stereoselectivity (68-98% de). In the absence of the A(1,3) strain (reduction of 6-substituted 2,4-dioxo-1-piperidines 7), the cis-4-hydroxy isomer was still obtained as the major product but the de values were consistently lower. 4-Hydroxy-6-oxo-1,2-piperidinedicarboxylate 2a, readily accessible from Boc-Asp-O[sup t]Bu (three steps, 63% overall yield), has proven to be an excellent building block for the synthesis of cis- and trans-4-hydroxypipecolates 17 and 24 (52 and 36% overall yield, respectively) and for the synthesis of a protected 4-hydroxylysine derivative 29 (41% overall yield). [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
View/download PDF

47. Pulse-on-Demand Operation for Precise High-Speed UV Laser Microstructuring.

Author

Kočica JJ, Mur J, Didierjean J, Guillossou A, Saby J, Petelin J, Mincuzzi G, and Petkovšek R

Abstract

Laser microstructuring has been studied extensively in the last decades due to its versatile, contactless processing and outstanding precision and structure quality on a wide range of materials. A limitation of the approach has been identified in the utilization of high average laser powers, with scanner movement fundamentally limited by laws of inertia. In this work, we apply a nanosecond UV laser working in an intrinsic pulse-on-demand mode, ensuring maximal utilization of the fastest commercially available galvanometric scanners at scanning speeds from 0 to 20 m/s. The effects of high-frequency pulse-on-demand operation were analyzed in terms of processing speeds, ablation efficiency, resulting surface quality, repeatability, and precision of the approach. Additionally, laser pulse duration was varied in single-digit nanosecond pulse durations and applied to high throughput microstructuring. We studied the effects of scanning speed on pulse-on-demand operation, single- and multipass laser percussion drilling performance, surface structuring of sensitive materials, and ablation efficiency for pulse durations in the range of 1-4 ns. We confirmed the pulse-on-demand operation suitability for microstructuring for a range of frequencies from below 1 kHz to 1.0 MHz with 5 ns timing precision and identified the scanners as the limiting factor even at full utilization. The ablation efficiency was improved with longer pulse durations, but structure quality degraded.

Published
2023
Full Text
View/download PDF

48. Hybrid Silica-Based Fillers in Nanocomposites: Influence of Isotropic/Isotropic and Isotropic/Anisotropic Fillers on Mechanical Properties of Styrene-Butadiene (SBR)-Based Rubber.

Author

Staropoli M, Rogé V, Moretto E, Didierjean J, Michel M, Duez B, Steiner P, Thielen G, Lenoble D, and Thomann JS

Abstract

The improvement of mechanical properties of polymer-based nanocomposites is usually obtained through a strong polymer-silica interaction. Most often, precipitated silica nanoparticles are used as filler. In this work, we study the synergetic effect occurring between dual silica-based fillers in a styrene-butadiene rubber (SBR)/polybutadiene (PBD) rubber matrix. Precipitated Highly Dispersed Silica (HDS) nanoparticles (10 nm) have been associated with spherical Stöber silica nanoparticles (250 nm) and anisotropic nano-Sepiolite. By imaging filler at nano scale through Scanning Transmission Electron Microscopy, we have shown that anisotropic fillers align only in presence of a critical amount of HDS. The dynamic mechanical analysis of rubber compounds confirms that this alignment leads to a stiffer nanocomposite when compared to Sepiolite alone. On the contrary, spherical 250 nm nanoparticles inhibit percolation network and reduce the nanocomposite stiffness.

Published
2021
Full Text
View/download PDF

49. Boric Acid as an Efficient Agent for the Control of Polydopamine Self-Assembly and Surface Properties.

Author

Schneider A, Hemmerlé J, Allais M, Didierjean J, Michel M, d'Ischia M, and Ball V

Abstract

The deposition of polydopamine (PDA) films on surfaces, a versatile deposition method with respect to the nature of the used substrate, is unfortunately accompanied by deposition of insoluble precipitates in solution after a prolonged oxidation time of dopamine solutions. Therefore, there is evident interest to find methods able to stop the deposition of PDA on surfaces and to simultaneously control the self-assembly of PDA in solution to get stable colloidal aggregates. In addition to proposed methods relying on the use of polymers like poly(vinyl alcohol) and proteins like human serum albumin, we show herein that boric acid is an efficient adjuvant that is simultaneously able to stop the self-assembly of PDA in solution as well as on surfaces and to change the adhesive properties of the resulting PDA coatings.

Published
2018
Full Text
View/download PDF

50. Yb:YAG single-crystal fiber amplifiers for picosecond lasers using the divided pulse amplification technique.

Author

Lesparre F, Gomes JT, Délen X, Martial I, Didierjean J, Pallmann W, Resan B, Druon F, Balembois F, and Georges P

Abstract

A two-stage master-oscillator power-amplifier (MOPA) system based on Yb:YAG single-crystal-fiber (SCF) technology and designed for high peak power is studied to significantly increase the pulse energy of a low-power picosecond laser. The first SCF amplifier has been designed for high gain. Using a gain medium optimized in terms of doping concentration and length, an optical gain of 32 dB has been demonstrated. The second amplifier stage designed for high energy using the divided pulse technique allows us to generate a recombined output pulse energy of 2 mJ at 12.5 kHz with a pulse duration of 6 ps corresponding to a peak power of 320 MW. Average powers ranging from 25 to 55 W with repetition rates varying from 12.5 to 500 kHz have been demonstrated.

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results