| 1. |
- Sun, Tao, et al.
(författare)
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Contrasting dynamics and trait controls in first-order root compared with leaf litter decomposition
- 2018
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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. ; 115:41, s. 10392-10397
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Tidskriftsartikel (refereegranskat)abstract
- Decomposition is a key component of the global carbon (C) cycle, yet current ecosystem C models do not adequately represent the contributions of plant roots and their mycorrhizae to this process. The understanding of decomposition dynamics and their control by traits is particularly limited for the most distal first-order roots. Here we followed decomposition of first-order roots and leaf litter from 35 woody plant species differing in mycorrhizal type over 6 years in a Chinese temperate forest. First-order roots decomposed more slowly (k = 0.11 ± 0.01 years−1) than did leaf litter (0.35 ± 0.02 years−1), losing only 35% of initial mass on average after 6 years of exposure in the field. In contrast to leaf litter, nonlignin root C chemistry (nonstructural carbohydrates, polyphenols) accounted for 82% of the large interspecific variation in first-order root decomposition. Leaf litter from ectomycorrhizal (EM) species decomposed more slowly than that from arbuscular mycorrhizal (AM) species, whereas first-order roots of EM species switched, after 2 years, from having slower to faster decomposition compared with those from AM species. The fundamentally different dynamics and control mechanisms of first-order root decomposition compared with those of leaf litter challenge current ecosystem C models, the recently suggested dichotomy between EM and AM plants, and the idea that common traits can predict decomposition across roots and leaves. Aspects of C chemistry unrelated to lignin or nitrogen, and not presently considered in decomposition models, controlled first-order root decomposition; thus, current paradigms of ecosystem C dynamics and model parameterization require revision.
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| 2. |
- Wang, Heyong, 1989-, et al.
(författare)
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Impacts of the Lattice Strain on Perovskite Light-Emitting Diodes
- 2023
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Ingår i: Advanced Energy Materials. - : Wiley-V C H Verlag GMBH. - 1614-6832 .- 1614-6840. ; 13:33
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Tidskriftsartikel (refereegranskat)abstract
- The development of perovskite light-emitting diodes (PeLEDs) with both high efficiency and excellent stability remains challenging. Herein, a strong correlation between the lattice strain in perovskite films and the stability of resulting PeLEDs is revealed. Based on high-efficiency PeLEDs, the device lifetime is optimized by rationally tailoring the lattice strain in perovskite films. A PeLED with a high peak external quantum efficiency of 18.2% and a long lifetime of 151 h (T-70, under a current density of 20 mA cm(-2)) is realized with a minimized lattice strain in the perovskite film. In addition, an increase in the lattice strain is found during the long-time device stability test, indicating that the degradation of the local perovskite lattice structure could be one of the degradation mechanisms for long-term stable PeLEDs.
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| 3. |
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| 4. |
- Sun, Hongguang, et al.
(författare)
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Average AoI-Minimal Trajectory Design for UAV-Assisted IoT Data Collection System: A Safe-TD3 Approach
- 2024
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Ingår i: IEEE Wireless Communications Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2162-2337 .- 2162-2345. ; 13:2, s. 530-534
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Tidskriftsartikel (refereegranskat)abstract
- This letter investigates an unmanned aerial vehicle (UAV)-assisted data collection strategy where the UAV trajectory is optimally designed to collect status update from several Internet of Things (IoT) nodes, so as to minimize the average Age of Information (AoI). We consider a practical three-dimensional (3D) urban environment, and design the UAV's trajectory by considering the data collection, flight, and energy constraints. Motivated by the critical safety requirements for the UAV, i.e., the energy constraint during the data collection, we exploit the twin delayed deep deterministic policy gradient (TD3) approach by enforcing the safety constraint throughout the training, and propose a Safe-TD3 based trajectory design for average AoI minimization. By evaluating the long-term safety constraint via the integrated cost network, we illustrate the superiority of the proposed Safe-TD3 based trajectory design algorithm over the benchmarks in reducing the safety constraint violations during the training process while achieving a lower average AoI.
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| 5. |
- Zhang, Pan, et al.
(författare)
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Photochemical hydrogen production with molecular devices comprising a zinc porphyrin and a cobaloxime catalyst
- 2012
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 55:7, s. 1274-1282
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Tidskriftsartikel (refereegranskat)abstract
- Two new noble-metal-free molecular devices, [{Co(dmgH)(2)Cl}{Zn(PyTPP)}] (1, dmgH = dimethyloxime, PyTPP = 5-(4-pyridyl)-10,15,20-triphenylporphyrin) and [{Co(dmgH)(2)Cl}{Zn(apPyTPP)}] (2, apPyTPP = 5-[4-(isonicotinamidyl)phenyl]-10,15,20-triphenylporphyrin), for light-driven hydrogen generation were prepared and spectroscopically characterized. The zinc porphyrin photosensitizer and the Co-III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges. The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores, Zn(PyTPP) (3) and Zn(apPyTPP) (4), suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices. Photochemical H-2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H-2 generation from water with triethylamine as a sacrificial electron donor in THF/H2O, with turnover numbers up to 46 and 35 for 1 and 2, respectively. In contrast to these molecular devices, the multicomponent catalyst of zinc porphyrin and [Co(dmgH)(2)PyCl] did not show any fluorescence quenching and as a consequence, no H-2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light. The plausible mechanism for the photochemical H-2 generation with these molecular devices is discussed.
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