| 1. |
- Li, Shuai, et al.
(författare)
-
Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells
- 2010
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 492:1-2, s. 392-395
-
Tidskriftsartikel (refereegranskat)abstract
- The composite of doped lanthanum gallate (La(0.9)Sr(0.1)Ga(0.8)Mg(0.2)O(2.85), LSGM) and doped ceria (Ce(0.8)Sm(0.2)O(1.9), CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO(2) phase and a minority impurity phase, Sm(3)Ga(5)O(12). The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 degrees C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.
|
|
| 2. |
- Andersson, Martin, et al.
(författare)
-
Modeling Validation and Simulation of an Anode Supported SOFC including Mass and Heat Transport, Fluid Flow and Chemical Reactions
- 2011
-
Ingår i: ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology. Collocated with ASME 2011 5th International Conference on Energy Sustainability, FUELCELL 2011. - 9780791854693 ; , s. 317-327
-
Konferensbidrag (refereegranskat)abstract
- Fuel cells are electrochemical devices that directly transform chemical energy into electricity, which are promising for future energy systems, since they are energy efficient and, when hydrogen is used as fuel, there are no direct emissions of greenhouse gases. The cell performance depends strongly on the material characteristics, the operating conditions and the chemical reactions that occur inside the cell. The chemical- And electrochemical reaction rates depend on temperature, material structure, catalytic activity, degradation and the partial pressures for the different species components. There is a lack of information, within the open literature, concerning the fundamentals behind these reactions. Experimental as well as modeling studies are needed to reduce this gap. In this study experimental data collected from an intermediate temperature standard SOFC with H2/H2O in the fuel stream are used to validate a previously developed computational fluid dynamics model based on the finite element method. The developed model is based on the governing equations of heat and mass transport and fluid flow, which are solved together with kinetic expressions for internal reforming reactions of hydrocarbon fuels and electrochemistry. This model is further updated to describe the experimental environment concerning cell design. Discussion on available active area for electrochemical reactions and average ionic transport distance from the anodic- to the cathodic three-phase boundary (TPB) are presented. The fuel inlet mole fractions are changed for the validated model to simulate a H2/H2O mixture and 30 % pre-reformed natural gas.
|
|
| 3. |
- Lapina, Alberto, et al.
(författare)
-
Synthesis of La 0.9Sr 0.1Ga 0.8Mg 0.2O 2.85 powder by gel combustion route with two-step doping strategy
- 2012
-
Ingår i: Journal of the European Ceramic Society. - : Elsevier. - 0955-2219 .- 1873-619X. ; 32:10, s. 2325-2331
-
Tidskriftsartikel (refereegranskat)abstract
- A two-step doping strategy was applied to the synthesis of La 0.9Sr 0.1Ga 0.8Mg 0.2O 2.85 (LSGM1020) powder by a gel combustion method. The Mg-doped LaGaO 3 powder was prepared in the first step, and Sr incorporation in the Mg-doped LaGaO 3 powder was done in the second step to obtain the final LSGM1020 powder. The two-step procedure is effective in preparing higher purity powders than the traditional one-step procedure. Rietveld refinement of X-ray powder diffraction (XRD) patterns shows that incorporation of Mg in LaGaO 3 in the first step enlarges the LaGaO 3 lattice: this facilitates the incorporation of Sr in the second doping step and thus high purity powder is obtained. Relatively phase pure LSGM1020 powder with only 3.1% of LaSrGaO 4 was obtained after calcination at 1300°C for 5h. Therefore, the two-step doping strategy is an effective procedure for the preparation of LSGM powders with high Sr- and Mg-doping levels.
|
|
| 4. |
- Lapina, Alberto, et al.
(författare)
-
Synthesis of La0.9Sr0.1Ga0.8Mg0.2O2.85 powder by gel combustion route with two-step doping strategy
- 2012
-
Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 32:10, s. 2325-2331
-
Tidskriftsartikel (refereegranskat)abstract
- A two-step doping strategy was applied to the synthesis of La0.9Sr0.1Ga0.8Mg0.2O2.85(LSGM1020) powder by a gel combustion method. The Mg-doped LaGaO3 powder was prepared in the first step, and Sr incorporation in the Mg-doped LaGaO3 powder was done in the second step to obtain the final LSGM1020 powder. The two-step procedure is effective in preparing higher purity powders than the traditional one-step procedure. Rietveld refinement of X-ray powder diffraction (XRD) patterns shows that incorporation of Mg in LaGaO3 in the first step enlarges the LaGaO3 lattice: this facilitates the incorporation of Sr in the second doping step and thus high purity powder is obtained. Relatively phase pure LSGM1020 powder with only 3.1% of LaSrGaO4 was obtained after calcination at 1300 degrees C for 5 h. Therefore, the two-step doping strategy is an effective procedure for the preparation of LSGM powders with high Sr- and Mg-doping levels.
|
|
| 5. |
- Li, Jia, et al.
(författare)
-
Oscillations of sub-membrane ATP in glucose-stimulated beta cells depend on negative feedback from Ca2
- 2013
-
Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 56:7, s. 1577-1586
-
Tidskriftsartikel (refereegranskat)abstract
- ATP links changes in glucose metabolism to electrical activity, Ca2+ signalling and insulin secretion in pancreatic beta cells. There is evidence that beta cell metabolism oscillates, but little is known about ATP dynamics at the plasma membrane, where regulation of ion channels and exocytosis occur. The sub-plasma-membrane ATP concentration ([ATP](pm)) was recorded in beta cells in intact mouse and human islets using total internal reflection microscopy and the fluorescent reporter Perceval. Glucose dose-dependently increased [ATP](pm) with half-maximal and maximal effects at 5.2 and 9 mmol/l, respectively. Additional elevations of glucose to 11 to 20 mmol/l promoted pronounced [ATP](pm) oscillations that were synchronised between neighbouring beta cells. [ATP](pm) increased further and the oscillations disappeared when voltage-dependent Ca2+ influx was prevented. In contrast, K+-depolarisation induced prompt lowering of [ATP](pm). Simultaneous recordings of [ATP](pm) and the sub-plasma-membrane Ca2+ concentration ([Ca2+](pm)) during the early glucose-induced response revealed that the initial [ATP](pm) elevation preceded, and was temporarily interrupted by the rise of [Ca2+](pm). During subsequent glucose-induced oscillations, the increases of [Ca2+](pm) correlated with lowering of [ATP](pm). In beta cells, glucose promotes pronounced oscillations of [ATP](pm), which depend on negative feedback from Ca2+ (.) The bidirectional interplay between these messengers in the sub-membrane space generates the metabolic and ionic oscillations that underlie pulsatile insulin secretion.
|
|
| 6. |
- Li, Shuai, et al.
(författare)
-
A Polymer Complexing Route for Low Temperature Synthesis of Perovskite Lanthanum Aluminate Powder
- 2010
-
Ingår i: HIGH-PERFORMANCE CERAMICS VI. ; 434 - 435, s. 863-867
-
Konferensbidrag (refereegranskat)abstract
- Lanthanum aluminate powders were prepared via a polymer complexing method by using PEG as complexing agent. The LaAlO3 powder was characterized by XRD and SEM. The influence of processing parameters such as molar ratio of PEG monomers to metal cations (PEG:Men+) and aging process on the phase purity and powder morphology were investigated. The calcined powder with the PEG:Me ratio larger than 2:1 may contain the secondary phase, namely La2O3. The formation of phase pure LaAlO3 powder occurs when the PEG:Men+ ratio is 1:1 or enough gelation time is involved. Although the phase pure powder is obtained by this PEG method, all the single phase LaAlO3 powders are found to have seriously aggregated particles. The weakly agglomerated powder morphology is only found in the powders which contain La2O3.
|
|
| 7. |
- Li, Shuai, et al.
(författare)
-
Synthesis and characterization of lanthanum aluminate powders via a polymer complexing plus combustion route
- 2012
-
Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 132:2-3, s. 309-315
-
Tidskriftsartikel (refereegranskat)abstract
- Lanthanum aluminate powders were prepared by a simple polymer complexing plus combustion method using PVA or PEG as complexing agent and fuel. The influence of different polymers on phase purity, powder morphology and sintering performance were investigated. Trace amount impurity La 2O 3 exists in the PEG powder, but it could be eliminated after high temperature sintering. The pure phase LaAlO 3 can be easily obtained in PVA powders calcined at 950 °C even severe aggregation always exists. PEG shows advantages over PVA in terms of the densification and microstructure control during sintering process. The high relative density of 97.0% and homogeneous fine microstructure with grain size < 3 μm can be obtained in the PEG-derived sample sintered at 1600 °C for 5 h. To obtain better quality LaAlO 3 powders through combustion route, PEG is preferred over PVA.
|
|
| 8. |
- Lin, Lili, et al.
(författare)
-
First-principles investigations on the anisotropic charge transport in 4,4 '-bis((E)-2-(naphthalen-2-yl)vinyl)-1,1 '-biphenyl single crystal
- 2014
-
Ingår i: Theoretical Chemistry accounts. - : Springer Science and Business Media LLC. - 1432-881X .- 1432-2234. ; 133:9, s. 1551-
-
Tidskriftsartikel (refereegranskat)abstract
- We applied the master equation method to investigate the anisotropic transport property of the 4,4'-bis((E)-2-(naphthalen-2-yl)vinyl)-1,1'-biphenyl molecular crystal based on first-principles calculation. It is found that the hole mobility has the largest value along the [100] direction, while electrons have the best transport property along the [010] direction. The anisotropic transport property was found to have close relationship with the charge transfer integral which is determined by the molecular stacking network in the crystals as well as the intermolecular frontier orbital overlap. In addition, the effect of the charge carrier density and the electronic field on the charge transport was also studied, and little effect was found except that the density is larger than 0.01 and the electronic field is increased to 1.0 x 106 V/cm. The kinetic Monte Carlo simulation method has also been used to study the anisotropic charge transport property, and consistent results were obtained as with the master equation method.
|
|
| 9. |
- Lin, Zhaowei, et al.
(författare)
-
Effects of BMP2 and VEGF165 on the osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells.
- 2014
-
Ingår i: Experimental and Therapeutic Medicine. - : Spandidos Publications. - 1792-1015 .- 1792-0981. ; 7:3, s. 625-629
-
Tidskriftsartikel (refereegranskat)abstract
- Bone marrow-derived mesenchymal stem cells (MSCs) are dominant seed cell sources for bone regeneration. Bone morphogenetic proteins (BMPs) initiate cartilage and bone formation in a sequential cascade. Vascular endothelial growth factor (VEGF) is an essential coordinator of extracellular matrix remodeling, angiogenesis and bone formation. In the present study, the effects of the vascular endothelial growth factor 165 (VEGF165) and bone morphogenetic protein 2 (BMP2) genes on bone regeneration were investigated by the lentivirus-mediated cotransfection of the two genes into rat bone marrow-derived MSCs. The successful co-expression of the two genes in the MSCs was confirmed using quantitative polymerase chain reaction (qPCR) and western blot analysis. The results of alizarin red and alkaline phosphatase (ALP) staining at 14 days subsequent to transfection showed that the area of staining in cells transfected with BMP2 alone was higher than that in cells transfected with BMP2 and VEGF165 or untransfected control cells, while the BMP2 + VEGF165 group showed significantly more staining than the untransfected control. This indicated that BMP2 alone exhibited a stronger effect in bone regeneration than BMP2 in combination with VEGF165. Similarly, in inducing culture medium, the ALP activity of the BMP2 + VEGF165 group was notably suppressed compared with that of the BMP2 group. The overexpression of VEGF165 inhibited BMP2-induced MSC differentiation and osteogenesis in vitro. Whether or not local VEGF gene therapy is likely to affect bone regeneration in vivo requires further investigation.
|
|
| 10. |
- Parvez, Khaled, et al.
(författare)
-
Exfoliation of Graphite into Graphene in Aqueous Solutions of Inorganic Salts
- 2014
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 136:16, s. 6083-6091
-
Tidskriftsartikel (refereegranskat)abstract
- Mass production of high-quality graphene sheets is essential for their practical application in electronics, optoelectronics, composite materials, and energy-storage devices. Here we report a prompt electrochemical exfoliation of graphene sheets into aqueous solutions of different inorganic salts ((NH4)(2)SO4, Na2SO4, K2SO4, etc.). Exfoliation in these electrolytes leads to graphene with a high yield (greater than85%, less than= 3 layers), large lateral size (up to 44 mu m), low oxidation degree (a C/O ratio of 17.2), and a remarkable hole mobility of 310 cm(2) V-1 s(-1). Further, highly conductive graphene films (11 Omega sq(-1)) are readily fabricated on an A4-size paper by applying brush painting of a concentrated graphene ink (10 mg mL(-1), in N,N-dimethylformamide). All-solid-state flexible supercapacitors manufactured on the basis of such graphene films deliver a high area capacitance of 11.3 mF cm(-2) and an excellent rate capability of 5000 mV s(-1). The described electrochemical exfoliation shows great promise for the industrial-scale synthesis of high-quality graphene for numerous advanced applications.
|
|
