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| 2. |
- Carlegrim, Elin, et al.
(författare)
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Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films : A model system for the V(TCNE)x room-temperature molecular magnet
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : Institutionen för teknik och naturvetenskap. - 1098-0121 .- 1550-235X. ; 77:5, s. 054420-1-054420-8
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Tidskriftsartikel (refereegranskat)abstract
- V(TCNE)(x), with TCNE=tetracyanoethylene and x similar to 2, is an organic-based molecular magnet with potential to be used in spintronic devices. With the aim of shedding light on the unoccupied frontier electronic structure of V(TCNE)(x) we have studied pristine TCNE and sodium-intercalated TCNE by near edge x-ray absorption fine structure (NEXAFS) spectroscopy as well as with theoretical calculations. Sodium-intercalated TCNE was used as a model system of the more complex V(TCNE)(x) and both experimental and theoretical results of the model compound have been used to interpret the NEXAFS spectra of V(TCNE)(x). By comparing the experimental and theoretical C K-edge of pristine TCNE, the contributions from the various carbon species (cyano and vinyl) could be disentangled. Upon fully sodium intercalation, TCNE is n doped with one electron per molecule and the features in the C and N K-edge spectra of pristine TCNE undergo strong modification caused by partially filling the TCNE lowest unoccupied molecular orbital (LUMO). When comparing the C and N K-edge NEXAFS spectra of fully sodium-doped TCNE with V(TCNE)(x), the spectra are similar except for broadening of the features which originates from structural disorder of the V(TCNE)(x) films. The combined results from the model system and V(TCNE)(x) suggest that the lowest unoccupied molecular orbital with density on the nitrogen atoms in V(TCNE)(x) has no significant hybridization with vanadium and is similar to the so-called singly occupied molecular orbital of the TCNE anion. This suggests that the LUMO of V(TCNE)(x) is TCNE- or vanadiumlike, in contrast to the frontier occupied electronic structure where the highest occupied molecular orbital is a hybridization between V(3d) and cyano carbons. The completely different nature of the unoccupied and occupied frontier electronic structure of the material will most likely affect both charge injection and transport properties of a spintronic device featuring V(TCNE)(x).
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| 3. |
- Huang, J., et al.
(författare)
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Direct preparation of CE0.8SM0.2O1.9 powders oxidized with H2O2 for low temperature SOFCS application
- 2005
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Ingår i: Proceedings of the 3rd International Conference on Fuel Cell Science, Engineering, and Technology. - : ASME Press. ; , s. 295-298
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Konferensbidrag (refereegranskat)abstract
- A novel method was developed to prepare fine doped ceria (DCO) powders directly. Ceria doped with 20 mol. % of samarium (Ce0.8Sm 0.2O1.9, SDC) was prepared by in-situ oxidization of hydroxide precipitates with H2O2 in the solutions. The resultant powder desiccated at 85°C overnight was characterized by X-ray diffraction (XRD), thermogravimetry /differential thermal analysis (TG/DTA), and transmission electron microscopy (TEM). The XRD pattern showed that the as-dried SDC powder is single phase with a cubic fluorite structure like that of pure CeO2. An anodesupported SOFC was also fabricated based on SDC and 20wt % (62mol. %Li2CO3-38 mol. %K2CO 3) composite electrolyte, LiNiO2 as cathode and NiO as anode, by cold pressing. Using hydrogen as the fuel and air as the oxidant, the I-V and I-P characteristics exhibit excellent performances and the maximum power densities are about 696, 469, 377 and 240 mWcm-2 at 650, 600, 550 and 500°C, respectively.
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| 4. |
- Jiang, G. X., et al.
(författare)
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Prediction of biodegradation rate constants of hydroxylated polychlorinated biphenyls by fungal laccases from Trametes versicolor and Pleurotus ostreatus
- 2008
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Ingår i: Bulletin of Environmental Contamination and Toxicology. - : Springer Science and Business Media LLC. - 0007-4861 .- 1432-0800. ; 81:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative structure-activity relationship (QSAR) models for fungal laccase-catalyzed degradation of different hydroxylated polychlorinated biphenyls (OH-PCBs) were developed using some fundamental quantum chemical descriptors. The cross-validated Q(cum)(2) values for the two optimal QSAR models are as high as 0.958 and 0.961 for laccases from Trametes versicolor and Pleurotus ostreatus, respectively, indicating good predictive abilities for laccase-catalyzed degradation of OH-PCBs. Results from this study show that increasing heat of formation (Delta H (f)) and frontier molecular orbital energy (i.e. E-LUMO + E-HOMO) values or decreasing frontier molecular orbital energy (i.e. EHOMO-1) and core-core repulsion energy (CCR) values leads to the increase of OH-PCB degradation rates by laccases.
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| 5. |
- Kirkland, Thomas A., et al.
(författare)
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Synthesis of glutamic acid analogs as potent inhibitors of leukotriene A(4) hydrolase
- 2008
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Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 16:9, s. 4963-4983
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Tidskriftsartikel (refereegranskat)abstract
- Leukotriene B-4 (LTB4) is a potent pro-inflammatory mediator that has been implicated in the pathogenesis of multiple diseases, including psoriasis, inflammatory bowel disease, multiple sclerosis and asthma. As a method to decrease the level of LTB4 and possibly identify novel treatments, inhibitors of the LTB4 biosynthetic enzyme, leukotriene A(4) hydrolase (LTA(4)-h), have been explored. Here we describe the discovery of a potent inhibitor of LTA(4)-h, arylamide of glutamic acid 4f, starting from the corresponding glycinamide 2. Analogs of 4f are then described, focusing on compounds that are both active and stable in whole blood. This effort culminated in the identification of amino alcohol 12a and amino ester 6b which meet these criteria.
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| 6. |
- Liu, X.R., et al.
(författare)
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Sulphate-ceria composite ceramics for energy environmental co-generation technology
- 2005
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Ingår i: HIGH-PERFORMANCE CERAMICS III, PTS 1 AND 2. - 0878499598 ; , s. 425-430
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Konferensbidrag (refereegranskat)abstract
- In this work ion conductivity and FC application were studied for the new type composite material based on SDC (samariurn doped ceria) and Li2SO4. Significant conductivity enhancement was achieved, e.g. 10(-2) - 0.4 Scm(-1) for the SDC-Li2SO4 compared to 10(-4) -10(-2) Scm(-1) for the SDC between 400 and 650degreesC. Some ion conductivity mechanisms were proposed correspondingly. Using the SDC-Li2SO4 composite materials as the electrolytes, we achieved high performances, 200-540 mWcm(-2). for intennediate temperature (450-650degreesC) solid oxide FC (ITSOFC) applications. Sulfates, typically Li2SO4, have an excellent chemical stability in sulfur containing atmosphere. The sulfate-ceria (SDC-Li2SO4) Composite materials can thus meet the demands to develop the sulfur tolerant and H2S FC technologies, which was also demonstrated successfully with significant importance for both fundamental and applied research.
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| 8. |
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| 9. |
- Zhang, Wenhua, et al.
(författare)
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Electronic structure of [121]tetramantane-6-thiol on gold and silver surfaces
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 130:054705
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism for electron photoemission of [121]tetramantane and its functionalized compound [121]tetramantane-6-thiol adsorbed on different noble metal surfaces has been investigated by density functional theory calculations. It is found that good chemical bonding between molecules and metal surfaces is a helpful but not a necessary condition for electron photoemission. A lower work function and weaker hybridization between the molecule and the metal could lead to much more efficient electron photoemission. It is observed that, neglecting final state effect, a simple ground state picture cannot result in negative electron affinity for the systems under investigation. Calculations have shown that by exciting an electron in the lowest unoccupied molecular orbital, the highest singly occupied molecular orbital of the molecule can be shifted above the vacuum level, resulting in negative electron affinity and emission of the accumulated electrons.
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| 10. |
- Zhu, Bin, et al.
(författare)
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Compatible cathode materials for high performance low temperature (300-600°C) solid oxide fuel cells
- 2006
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Ingår i: Proceedings of 4th International ASME Conference on Fuel Cell Science, Engineering and Technology, FUELCELL2006. - : ASMEDC.
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Konferensbidrag (refereegranskat)abstract
- We have made extensive efforts to develop various compatible electrode materials for the ceria-based composite (CBC) electrolytes, which have been, reported as most advanced LTSOFC electrolyte materials (Zhu, 2003). The electrode materials we have investigated can be classified as four categories: i) LSCCF (LaSrCoCaFeO) and BSCF perovskite oxides applied for our CBC electrolyte LTSOFCs; ii) LFN (LaFeO-based oxides, e.g. LaFe0.8Ni 0.2O3) perovskite oxides; iii) lithiated oxides: e.g. LiNiOx, LiVOx or LiCuOx are typical cathode examples for the CBC LTSOFCs; iv) other mixed oxide systems, most common in a mixture of two-oxide phases, such CuOx-NiOx, CuO-ZnO etc. systems with or without lithiation are developed for the CBC systems, especially for direct alcohol LTSOFCs. These cathode materials used for the CBC electrolyte LTSOFCs have demonstrated excellent performances at 300-600°C, e.g. 1000 mWcm-2 was achieved at 580°C. The LTSOFCs can be operated with a wide range of fuels, e.g. hydrogen, methanol, ethanol etc with great potential for applications.
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