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排序方式: 共有142条查询结果,搜索用时 15 毫秒
1.
C. Caldera N. Caponio C. de Bernardi F. Delpiano G. Destefanis S. Morasca M. Puleo G. Schiavini F. Schiattone A. Stano E. Legros M. Billard 《Optical and Quantum Electronics》1994,26(5):S529-S545
Optical waveguide 3-dB couplers integrated on semicondutors have been studied, designed and fabricated, using both bulk and diluted multi-quantum-well InGaAsP/InP-based materials, grown by MOCVD. The device structure is based on the two-mode interference (TMI) principle and is fully compatible for integration with the optoelectronic and electronic components of a coherent receiver. Bulk material couplers provide an output balanced within 0.05 dB per nanometer and an excess loss of 1.4 dB, compared to a straight guide, while coupling loss to a tapered-lensed single mode fibre is 4 dB.Improved coupling efficiency to single-mode fibres is achieved by use of moderately diluted multi-quantum-well waveguides, which include InGaAsP wells and InP barriers: coupling loss to a tapered-lensed single-mode fibre as low as 0.5 dB and excess loss of 1.8 dB are featured. Couplers fabricated with this waveguide structure have a balance sensitivity of 0.03 to 0.04 dB per nanometer.A moderately diluted multi-quantum-well 3-dB coupler has been permanently pigtailed and butt-coupled to a dual balanced PIN photoreceiver. This hybrid assembly was tested in a coherent transmission system at 155 and 622 Mbits-1 showing sensitivities, for 10-9 BER, of about-38.0 dBm and-28.8 dBm, respectively. 相似文献
2.
Under Lewis acid activation, hemiaminals of trifluoroacetaldehyde and related (fluoroalkyl)aldehydes generate iminium species that can react with various nucleophiles to provide fluorinated amines. 相似文献
3.
M. Bouby H. J. Mac Cordick I. Billard 《Journal of Radioanalytical and Nuclear Chemistry》1996,210(1):161-169
The properties of mobile, 5% w/w cell suspensions ofMycobacterium phlei have been examined for their capacity to adsorb and retain uranyl(VI) and neptuny(V) cations from nitrate-buffered solutions at pH 1. Equilibrium conditions of sorption were attained after 3 hours for concentrations (C) in the range 0.015–18 mM cation and indicated a maximum specific adsorption capacity (Qe
max) of 182 mol/g dry biomass forC10 mM. NpO
2
+
generally showed higherQe values than UO
2
2+
at corresponding concentrations. Lixiviation tests with cation-loaded biomass in neutral and acidic media indicated that the extent of desorption did not vary extensively between pH 7 and pH 1 and did not exceed 3% for U and 1% for Np ions at pH 7 during 7-day periods of treatment. Analogous experiments with U-loaded biomass subjected to neutron activation prior to lixiviation enabled retention measurements for various fission-product isotopes produced in situ and showed that retention of239Np formed within the cellular matrix was >99% at pH 7 and 94% at pH 1. 相似文献
4.
Kevin Grollier Arnaud De Zordo-Banliat Flavien Bourdreux Dr. Bruce Pegot Dr. Guillaume Dagousset Dr. Emmanuel Magnier Dr. Thierry Billard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):6028-6033
The synthesis of molecules bearing (trifluoromethylselenyl)methylchalcogenyl groups is described via an efficient two-step strategy based on a metal-free photoredox catalyzed decarboxylative trifluoromethylselenolation with good yields up to 88 %, which raised to 98 % in flow chemistry conditions. The flow methods allowed also to scale up the reaction. The mechanism of this key reaction was studied. The physicochemical characterization of these emerging groups was performed by determining their Hansch–Leo lipophilicity parameters with high values up to 2.24. This reaction was also extended to perfluoroalkylselenolation with yields up to 95 %. Finally, this method was successfully applied to the functionalization of relevant bioactive molecules such as tocopherol or estrone derivatives. 相似文献
5.
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7.
The total miscibility method is applied to study the recently discovered mesophases of disc-like molecules, benzene-hexa-n-alkanoates. These compounds do not form continuous solid solutions, but are totally miscible in the liquid and mesomorphic
states. The virtual mesophase-isotropic transition temperature for the hexanoate compound derived from the miscibility diagram
is in excellent accord with that obtained from the previously reported pressure-temperature phase diagram. With simplifying
assumptions, it is possible to predict with acceptable reliability the isobaric binary phase diagrams of any two members of
the series. The real and virtual mesophase-liquid transition temperatures are linear functions of the molecular weight. On
the other hand, a plot of the crystal-liquid transition temperatures versus the molecular weight exhibits a minimum. Total
miscibility in the mesomorphic state is not observed for two members of different discogenic series, but the existence of
different mesophase types is not proved. Lyotropic mesomorphism for a disc-like mesophase is established. 相似文献
8.
E.?Gourba P.?Briois A.?RinguedéEmail author M.?Cassir A.?Billard 《Journal of Solid State Electrochemistry》2004,8(9):633-637
Gadolinia-doped ceria (GDC) remains, up to now, the most promising candidate for replacing yttria-stabilised zirconia (YSZ) as electrolyte for solid oxide fuel cells (SOFC) operating at intermediate temperature. Literature data point out that GDC could be used as electrolyte, anode material, or interlayers for avoiding the chemical interactions occurring at the interfaces. In the present work, GDC thin layers were produced by d.c. reactive magnetron sputtering and deposited over a thickness domain between 450 nm and 5.5 µm. According to our knowledge, the deposition of GDC sputtered layers has never been reported. The physicochemical features of these thin films have been characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Impedance measurements have been carried out in order to determine the electrical properties of electrolyte thin films and in particular their ionic conductivity.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003 相似文献
9.
Aurélie Assalit Thierry Billard Stéphane Chambert Bernard R. Langlois Yves Queneau Diane Coe 《Tetrahedron: Asymmetry》2009,20(5):593-601
A series of 10 new carbohydrate-substituted bipyridines were prepared from 2,2′-bipyridine-3,3′-dicarboxylic acid, itself easily available from ortho-phenanthroline. As a preliminary exploration of their use as chiral ligands, Cu(II)-catalysed asymmetric electrophilic fluorination of model β-ketoesters using these simple and easily accessible chiral bipyridines was studied. Only modest enantioselectivity was observed in this reaction, although the ee was in a similar range as those provided by known and more elaborate ligands. 相似文献
10.
A recent photothermal technique has been used to study the smectic A-nematic and nematic-isotropic phase transitions in 4-n-octyl-4prime;-cyanobiphenyl and in binary mixtures of 4-n-octyl- and 4-n-octyloxy-4prime;-cyanobiphenyl. A numerical analysis shows that both amplitude and phase of the photothermal signal are sensitive to the change of certain thermal parameters for the sample. 相似文献