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| 2. |
- Tian, Yupeng, et al.
(författare)
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Two novel two-photon polymerization initiators with extensive application prospects
- 2004
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Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 388:4-6, s. 325-329
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Tidskriftsartikel (refereegranskat)abstract
- Two novel two-photon polymerization initiators, 10-ethyl-3-E-(4-(N,N′-di-n-butylamino)styryl)phenothiazine 5 and 10-ethyl-3,7-E,E-bis(4-(N,N′-di-n-butyl amino)styryl)phenothiazine 6, have been efficiently synthesized with room temperature solid phase Wittig reaction. Two initiators were found to exhibit good single-photon fluorescence emission and their quantum yields, lifetimes and solvent effects have been studied in detail. Two-photon fluorescence spectra were investigated under 800 nm fs laser pulse and two-photon absorption (TPA) cross-sections of the initiators have been evaluated by theoretical calculation.Two-photon initiating polymerization microfabrication experiments have been carried out and artificial defects were made and polymerization mechanism was also discussed.
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| 4. |
- Toprak, Muhammet S., et al.
(författare)
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The impact of nanostructuring on the thermal conductivity of thermoelectric CoSb3
- 2004
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 14:12, s. 1189-1196
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Tidskriftsartikel (refereegranskat)abstract
- The high concentration of grain boundaries provided by nanostructuring is expected to lower the thermal conductivity of thermoelectric materials, which favors an increase in their thermoelectric figure-of-merit, ZT. A novel chemical alloying method has been used for the synthesis of nanoengineered-skutterudite CoSb3. The CoSb3 powders were annealed for different durations to obtain a set of samples with different particle sizes. The samples were then compacted into pellets by uniaxial pressing under various conditions and used for the thermoelectric characterization. The transport properties were investigated by measuring the Seebeck coefficient and the electrical and thermal conductivities in the temperature range 300 K to 650 K. A substantial reduction in the thermal conductivity of CoSb3 was observed with decreasing grain size in the nanometer region. For an average grain size of 140 nm, the thermal conductivity was reduced by almost an order of magnitude compared to that of a single crystalline or highly annealed polycrystalline material. The highest ZT value obtained was 0.17 at 611 K for a sample with an average grain size of 220 nm. The observed decrease in the thermal conductivity with decreasing grain size is quantified using a model that combines the macroscopic effective medium approaches with the concept of the Kapitza resistance. The compacted samples exhibit Kapitza resistances typical of semiconductors and comparable to those of Si-Ge alloys.
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| 5. |
- Uheida, Abdusalam, et al.
(författare)
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Thermodynamic modeling of extraction equilibria of platinum and palladium with nonylthiourea from hydrochloric acid media
- 2004
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Ingår i: Separation science and technology (Print). - : Informa UK Limited. - 0149-6395 .- 1520-5754. ; 39:15, s. 3665-3677
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Tidskriftsartikel (refereegranskat)abstract
- Models of extraction equilibria of Pt(IV) and Pd(II) with Nonylthiourea (NTH) from HCl media have been studied. The conditional equilibrium constants and the stoichiometry of the extracted species of Pt(IV) with NTH at different ionic strengths obtained by numerical analysis using the LETAGROP-DISTR program are reported. The dependence of the extraction constant values on the ionic strength has been analysed using the Specific Interaction Theory (SIT), from which the respective thermodynamic equilibrium constants of the extraction of Pt(IV) and Pd(II) with NTH have been determined. The thermodynamic equilibrium constants determined for Pt(IV) are log K-11o=5+/-1 and log K-14(o)=14.6+/-0.2, while for Pd(II) log K-11(o)=4.9+/-0.1 and log K-12(o)=9.17+/-0.08. The interaction coefficients, epsilon, for the pairs (H+, PtCl62-) and (H+, PdCl42-) have also been estimated to be 0.30+/-0.08 and 0.41+/-0.02, respectively.
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| 6. |
- Uheida, Abdusalam, et al.
(författare)
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Transport of palladium(II) through hollow fiber supported liquid membrane facilitated by nonylthiourea
- 2004
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 241:2, s. 289-295
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Tidskriftsartikel (refereegranskat)abstract
- The facilitated transport of Pd(II) from chloride media has been investigated through a hollow-fiber supported liquid membrane using nonylthiourea (NTH) as a carrier. The influence of the chemical conditions on the permeability of Pd(II) is reported. A model is presented that describes the transport mechanism, consisting of diffusion through a feed aqueous diffusion layer, a fast interfacial chemical reaction, and diffusion of carrier and its metal complex through the organic membrane. The diffusion resistances through organic membrane (Delta(org)) and through aqueous layer (Delta(aq)), respectively, have been calculated from the proposed model. The permeability of Pd(II) seems to be governed by the diffusion of Pd(II) species through the hollow fiber supported liquid membrane with PdCl2(NTH)(2) as a predominant carrier and PdCl2(NTH)to a lesser extent, though both have similar diffusion coefficients.
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| 7. |
- Zhang, X. L., et al.
(författare)
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Automatic real-time control for gain-flattened fiber Raman amplifiers
- 2004
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 239:01-3, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- An automatic control algorithm for flattening the gain of a fiber Raman amplifier is derived from the Raman scattering equations. A pseudo-inverse gain matrix is introduced to adjust the powers of the pump lasers. The algorithm is simple, fast, effective, robust and insensitive to the length and type of the fiber. It is demonstrated experimentally that the gain flattening for Raman amplifiers comprising various types and lengths of fiber and with different target gains can be achieved automatically with this algorithm. The algorithm converges for both small and large input signal. Flattened Raman gain with a fluctuation less than 0.40 dB over a 50-nm bandwidth for a 50-km SMF or less than 0.20 dB over a 40-nm bandwidth for a 6.6-km dispersion compensated fiber is realized in the experiment.
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