| 1. |
- Wei, Ting, et al.
(författare)
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Developed and developing world responsibilities for historical climate change and CO2 mitigation
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:32, s. 12911-12915
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Tidskriftsartikel (refereegranskat)abstract
- At the United Nations Framework Convention on Climate Change Conference in Cancun, in November 2010, the Heads of State reached an agreement on the aim of limiting the global temperature rise to 2 degrees C relative to preindustrial levels. They recognized that long-term future warming is primarily constrained by cumulative anthropogenic greenhouse gas emissions, that deep cuts in global emissions are required, and that action based on equity must be taken to meet this objective. However, negotiations on emission reduction among countries are increasingly fraught with difficulty, partly because of arguments about the responsibility for the ongoing temperature rise. Simulations with two earth-system models (NCAR/CESM and BNU-ESM) demonstrate that developed countries had contributed about 60-80%, developing countries about 20-40%, to the global temperature rise, upper ocean warming, and sea-ice reduction by 2005. Enacting pledges made at Cancun with continuation to 2100 leads to a reduction in global temperature rise relative to business as usual with a 1/3-2/3 (CESM 33-67%, BNU-ESM 35-65%) contribution from developed and developing countries, respectively. To prevent a temperature rise by 2 degrees C or more in 2100, it is necessary to fill the gap with more ambitious mitigation efforts.
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| 2. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 3. |
- Chen, Si, et al.
(författare)
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A graphene field-effect capacitor sensor in electrolyte
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:15, s. 154106-
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Tidskriftsartikel (refereegranskat)abstract
- The unique electronic properties of graphene are exploited for field-effect sensing in both capacitor and transistor modes when operating the sensor device in electrolyte. The device is fabricated using large-area graphene thin films prepared by means of layer-by-layer stacking. Although essentially the same device, its operation in the capacitor mode is found to yield more information than in the transistor mode. The capacitor sensor can simultaneously detect the variations of surface potential and electrical-double-layer capacitance at the graphene/electrolyte interface when altering the ion concentration. The capacitor-mode operation further facilitates studies of the molecular binding-adsorption kinetics by monitoring the capacitance transient
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| 4. |
- Deng, Yunfeng, et al.
(författare)
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A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives
- 2014
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 140:12, s. 124304-
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Tidskriftsartikel (refereegranskat)abstract
- The core-hole excitation spectra-near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C59N and its derivatives (C59N)(+), C59HN, (C59N)(2), and C59N-C-60, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham(ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C59N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C59N-C-60 is confirmed to be related to the electron transfer from the C59N part to the C-60 part in this charge-transfer complex.
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| 5. |
- Gao, Bin, et al.
(författare)
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Plasmon resonances in linear noble-metal chains
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:19, s. 194307-
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Tidskriftsartikel (refereegranskat)abstract
- The electronic excitations of three noble-metall chains-copper, silver, and gold-have been investigated at the time-dependent density functional theory level. The reduced single-electron density matrix is propagated according to the Liouville-von Neumann equation in the real-time domain after an impulse excitation. The propagation in the real-time domain enables us to investigate the formation and size evolution of electronic excitations in these metallic chains with different number of atoms, up to a total of 26 atoms. The longitudinal oscillations at lower excitation energies are dominated by s -> p transitions in these chains and have collective or central resonances, while the first peak involving d -> p transitions in the longitudinal mode appears at a higher excitation energy and shows collective resonances. In the transverse oscillations, there are in most cases d -> p transitions in each resonance, which can be attributed to either central or end resonances. Convergence of the oscillations, in particular those involving the collective and central resonances in the three noble-metal chains can only be observed for chains with 18 atoms or more. Different spectroscopic characteristics among these three metallic chains can be attributed to their different electronic structures, in particular the relativistic effects in the gold chains have a dramatic effect on their electronic structures and excitations.
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| 6. |
- Gao, Bin, et al.
(författare)
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Shape-Dependent Electronic Excitations in Metallic Chains
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:24, s. 13059-13069
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Tidskriftsartikel (refereegranskat)abstract
- The electronic excitations of silver chains with different geometries (linear, circle, arc and zigzag chains) have been investigated at the time-dependent density functional theory level, by solving the equation of motion of the reduced single-electron density matrix in the real-time domain. A scaling parameter 0 <= lambda <= 1 has been introduced to adjust the two-electron contributions during propagation in the time domain in a way that allows us to distinguish different electronic excitations plasmon and single-particle excitations. The dipole responses, in particular the plasmon resonances of these metallic chains to an external delta-pulse, show a strong dependence on their geometric structures. In most cases, the dipole responses of these chains possess great tunability when altering their geometric parameters the radius of the circle and arc chains, and the bond angle of the zigzag chains. Some excitations in these chains also show a wide tunable excitation energy range, more than 1 eV, making it possible to fine-tune the excitations of the metallic chains at an atomic scale.
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| 7. |
- Gao, Qin, et al.
(författare)
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甲基对硫磷水解酶分离条件的量热学优化
- 2012
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Ingår i: Guangzhou Chemical Industry and Technology. ; 40:8, s. 7-9
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Tidskriftsartikel (refereegranskat)abstract
- Methyl parathion hydrolase （ MPH ） as and bovine serum albumin （BSA） as hybrid proteins, the target protein, bovine hemoglobin （BHb）, myoglobin （Mb） enzyme thermal analysis was used to determine the best separation condition of methyl parathion hydrolase through the study of pH and the NaC1 concentration in mobile phase. The results showed that at pH 8.0, NaC1 concentration of 0.8 mol/L, the separation condition of methyl parathion hydrolase was the best which consistent with the condition reported in the literature.
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| 8. |
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| 9. |
- Gao, Zhan, et al.
(författare)
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Development of methanol-fueled low-temperature solid oxide fuel cells
- 2011
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 35:8, s. 690-696
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Tidskriftsartikel (refereegranskat)abstract
- Low-temperature solid oxide fuel cell (SOFC, 300-600 degrees C) technology fueled by methanol possessing significant importance and application in polygenerations has been developed. Thermodynamic analysis of methanol gas-phase compositions and carbon formation indicates that direct operation on methanol between 450 and 600 degrees C may result in significant carbon deposition. A water steam/methanol ratio of 1/1 can completely suppress carbon formation in the same time enrich H(2) production composition. Fuel cells were fabricated using ceria-carbonate composite electrolytes and examined at 450-600 degrees C. The maximum power density of 603 and 431 mW cm(-2) was achieved at 600 and 500 degrees C, respectively, using water steam/methanol with the ratio of 1/1 and ambient air as fuel and oxidant. These results provide great potential for development of the direct methanol low-temperature SOFC for polygenerations.
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| 10. |
- Gao, Zhan, et al.
(författare)
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Electrochemical Characterization on SDC/Na2CO3 Nanocomposite Electrolyte for Low Temperature Solid Oxide Fuel Cells
- 2011
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 11:6, s. 5413-5417
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Tidskriftsartikel (refereegranskat)abstract
- Our previous work has demonstrated that novel core-shell SDC/Na2CO3 nanocomposite electrolyte possesses great potential for the development of low temperature (300-600 degrees C) solid oxide fuel cells. This work further characterizes the nanocomposite SDC/Na2CO3 electrochemical properties and conduction mechanism. The microstructure of the nanocomposite sintered at different temperatures was analyzed through scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrical and electrochemical properties were studied. Significant conductivity enhancement was observed in the H-2 atmosphere compared with that of air atmosphere. The ratiocination of proton conduction rather than electronic conduction has been proposed consequently based on the observation of fuel cell performance. The fuel cell performance with peak power density of 375 mW cm(-2) at 550 degrees C has been achieved. A.C. impedance for the fuel cell under open circuit voltage (OCV) conditions illustrates the electrode polarization process is predominant in rate determination.
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