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- 2019
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Tidskriftsartikel (refereegranskat)
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- Chen, X, et al.
(författare)
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Negative thermal quenching of below-bandgap photoluminescence in InPBi
- 2017
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 110:5
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a temperature-dependent (10-280 K) photoluminescence (PL) study of below-bandgap electron-hole recombinations and anomalous negative thermal quenching of PL intensity in InP1- xBix (x = 0.019 and 0.023). Four PL features are well resolved by curve-fitting of the PL spectra, of which the energies exhibit different temperature dependence. The integral intensities of the two high-energy features diminish monotonically as temperature rises up, while those of the two low-energy features decrease below but increase anomalously above 180 K. A phenomenological model is established that the residual electrons in the final state of the PL transition transfer into nonradiative state via thermal hopping, and the thermal hopping produces in parallel holes in the final state and hence enhances the radiative recombination significantly. A reasonable interpretation of the PL processes in InPBi is achieved, and the activation energies of the PL quenching and thermal hopping are deduced. © 2017 Author(s).
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- Christensen, Kirsten E, et al.
(författare)
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A germanate built from 68126 cavity co-templated by a (H2O)16 water cluster and 2-methylpiperazine
- 2008
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 47:41, s. 7868-7871
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Tidskriftsartikel (refereegranskat)abstract
- Totally tubular: A new tubular germanate is cotemplated by 2-methylpiperazine and an (H2O)16 cluster in a hydro(solvo)thermal synthesis. The germanate features a large, highly symmetric 68126 cavity (see picture; yellow sphere) built from 12 Ge7X19 (X=O, OH, F) clusters (GeX6 red, GeX5 yellow, GeX4 green).
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- Herrick, Ariane L, et al.
(författare)
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Treatment outcome in early diffuse cutaneous systemic sclerosis : The European Scleroderma Observational Study (ESOS)
- 2017
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 76:7, s. 1207-1218
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The rarity of early diffuse cutaneous systemic sclerosis (dcSSc) makes randomised controlled trials very difficult. We aimed to use an observational approach to compare effectiveness of currently used treatment approaches. Methods: This was a prospective, observational cohort study of early dcSSc (within three years of onset of skin thickening). Clinicians selected one of four protocols for each patient: methotrexate, mycophenolate mofetil (MMF), cyclophosphamide or 'no immunosuppressant'. Patients were assessed three-monthly for up to 24 months. The primary outcome was the change in modified Rodnan skin score (mRSS). Confounding by indication at baseline was accounted for using inverse probability of treatment (IPT) weights. As a secondary outcome, an IPT-weighted Cox model was used to test for differences in survival. Results Of 326 patients recruited from 50 centres, 65 were prescribed methotrexate, 118 MMF, 87 cyclophosphamide and 56 no immunosuppressant. 276 (84.7%) patients completed 12 and 234 (71.7%) 24 months follow-up (or reached last visit date). There were statistically significant reductions in mRSS at 12 months in all groups: -4.0 (-5.2 to -2.7) units for methotrexate, -4.1 (-5.3 to -2.9) for MMF, -3.3 (-4.9 to -1.7) for cyclophosphamide and -2.2 (-4.0 to -0.3) for no immunosuppressant (p value for between-group differences=0.346). There were no statistically significant differences in survival between protocols before (p=0.389) or after weighting (p=0.440), but survival was poorest in the no immunosuppressant group (84.0%) at 24 months. Conclusions: These findings may support using immunosuppressants for early dcSSc but suggest that overall benefit is modest over 12 months and that better treatments are needed.
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- Liu, Juanjuan, et al.
(författare)
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Electrically injected GaAsBi/GaAs single quantum well laser diodes
- 2017
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226 .- 2158-3226. ; 7:11, s. Article Number: 115006 -
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Tidskriftsartikel (refereegranskat)abstract
- We present electrically injected GaAs/GaAsBi single quantum well laser diodes (LDs) emitting at a record long wavelength of 1141 nm at room temperature grown by molecular beam epitaxy. The LDs have excellent device performances with internal quantum efficiency of 86%, internal loss of 10 cm-1 and transparency current density of 196 A/cm2. The LDs can operate under continuous-wave mode up to 273 K. The characteristic temperature are extracted to be 125 K in the temperature range of 77?150 K, and reduced to 90 K in the range of 150?273 K. The temperature coefficient of 0.3 nm/K is extracted in the temperature range of 77?273 K.
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- Liu, Yanrong, et al.
(författare)
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Cascade utilization of lignocellulosic biomass to high-value products
- 2019
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 21:13, s. 3499-3535
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Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic biomass is a potential sustainable feedstock to replace fossil fuels. However, the complex structure of biomass makes it difficult to convert into high-value products. Utilization of lignocellulosic biomass in a green and effective way is of great significance for sustainable development. Based on the analysis of different options, we proposed that cascade utilization according to its composition, characteristics, and nature is the best way to utilize the lignocellulosic biomass. To promote the cascade utilization of lignocellulosic biomass, this article provides a review of the latest research results from the aspect of cascade utilization of lignocellulosic biomass covering the whole chain from pretreatment to high-value products, and the research on the non-conventional pretreatments including microwave irradiation, supercritical fluids, ultrasonic irradiation, electric field, hydrodynamic cavitation, and ionic liquids are presented in detail and evaluated by 4 proposed levels, and the newly developed high-value applications were further overviewed for lignin (carbon/graphene/carbon nano-tubes, dye dispersants, bioplastics, and aerogels), cellulose (cellulose-based ionic liquids, functional composites, adsorbent materials, carbon, and aerogels), and hemicellulose (films and pharmaceutical carriers), respectively. Finally, perspectives on the future research on the cascade utilization of lignocellulosic biomass are highlighted.
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- Liu, Yanrong, et al.
(författare)
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Preparation of MWCNTs-Graphene-Cellulose Fiber with Ionic Liquids
- 2019
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 7:24, s. 20013-20021
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Tidskriftsartikel (refereegranskat)abstract
- The conductive multiwalled carbon nanotubes (MWCNTs)-graphene sheets (rGOs)-cellulose fiber was prepared with an eco-friendly wet-spinning method in which ionic liquid (IL) was used as both green solvent and dispersant. It was found that the selected IL 1-ethyl-3-methylimidazolium diethyl phosphate (EmimDep) shows remarkable capacities for dissolving cellulose and dispersing MWCNTs, and the synergistic effect of MWCNTs, rGOs, and cellulose results in a high electrical conductivity of 1195 S/m of MWCNTs-rGOs-cellulose fibers. Macropores and the double-layer structure of MWCNTs and rGOs can be observed by SEM in the studied fibers, and the number of macropores decreased with increasing rGOs amount, which is consistent with the result of the specific surface area. In addition, the prepared MWCNTs-rGOs-cellulose fibers present a nearly perfect electrical double-layer structure. The MWCNTs-rGOs-cellulose fiber with a mass ratio of 2:3:1 shows the best performance as the electrode candidate, with an electrical conductivity of 1195 S/m, specific capacitance of 597 mF/cm2, and specific surface area of 91 m2/g. Furthermore, the results from the molecular dynamics (MD) simulation evidenced that EmimDep can disperse CNTs effectively at 363.15 K, 1 atm compared to rGOs; the synergy effect of CNT and rGO exhibit great potential to enhance the dispersion than each individual component.
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- Liu, Yanrong, et al.
(författare)
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Study on ionic liquid/cellulose/coagulator phase diagram and its application in green spinning process
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 289
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the cellulose phase separation behavior was investigated by using ionic liquids (ILs) as novel solvents to acquire a green process for cellulose fiber spinning. The cloud point titration method combined with the turbidity correlation equation was used to obtain the ternary diagram of IL/cellulose/coagulator throughout the whole compositional range. The effects of the type of ILs, the cellulose materials, the kind of coagulators and the regeneration temperatures for cellulose fiber manufacturing process on the phase separation behavior were studied systematically. It was found that the linearized cloud point (LCP) curve correlation fits to experimental data well and can be used to quantify the optimized coagulator, and among the studied cases, the system of [EMIM]DEP, cotton pulp and water with the regeneration temperature at 298.15 K is the best. Meanwhile, COSMO-RS was used to predict the interaction between solvent, cellulose and coagulator, and the comparison with the LCP correlation shows good agreement. The crystal structure of the regenerated cotton pulp was determined with XRD, and the result evidences that the crystal structure of the regenerated cellulose transforms from cellulose I to cellulose II. The crystallinity decreases from 96.0% (raw cotton pulp) to 85.6% after 24 h dissolution in [EMIM]DEP at 363.15 K, and it has a slight deviation from 24 h to 72 h, which illustrates that the spinning process can run continuously at 363.15 K when using [EMIM]DEP as the solvent.
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