| 1. |
- He, Wei, et al.
(författare)
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China's Terrestrial Carbon Sink Over 2010–2015 Constrained by Satellite Observations of Atmospheric CO2 and Land Surface Variables
- 2022
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Ingår i: Journal of Geophysical Research: Biogeosciences. - 2169-8953. ; 127:2
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Tidskriftsartikel (refereegranskat)abstract
- The magnitude and distribution of China's terrestrial carbon sink remain uncertain due to insufficient constraints at large scales, whereby satellite data offer great potential for reducing the uncertainty. Here, we present two carbon sink estimates for China constrained either by satellite CO2 column concentrations (XCO2) within the Global Carbon Assimilation System or by remotely sensed soil moisture and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) in addition to in situ CO2 observations within the Carbon Cycle Data Assimilation System. They point to a moderate size of carbon sinks of 0.34 ± 0.14 (mean ± unc.) and 0.43 ± 0.09 PgC/yr during 2010–2015, which are supported by an inventory-based estimate for forest and soil carbon sink (0.26 PgC/yr) and fall in the range of contemporary ensemble atmospheric inversions (0.25–0.48 PgC/yr). They also agree reasonably well on interannual variations, which reflect the carbon sink anomalies induced by regional droughts in southwest China. Furthermore, their spatial distributions are broadly consistent that of the forest inventory-based estimate, indicating that the largest carbon sinks locate in central and eastern China. Their estimates for forest carbon sink coincide fairly well with the inventory-based estimate across different regions, especially when aggregated to the north and south of China. Although enhanced recently by afforestation, China's carbon sink was also significantly weakened by regional droughts, which were often not fully represented in previous in situ CO2-based inversions due to insufficient observations. Our results suggest that satellite-based atmospheric CO2 and land surface observations are vital in characterizing terrestrial net carbon fluxes at regional scales.
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| 2. |
- Jiang, Xiangang, et al.
(författare)
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Internal erosion of debris-flow deposits triggered by seepage
- 2023
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Ingår i: Engineering Geology. - : Elsevier BV. - 0013-7952 .- 1872-6917. ; 314, s. 107015-
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Tidskriftsartikel (refereegranskat)abstract
- Debris flows can be triggered by runoffs at considerably steep natural channels and streams. Specifically, runoffgenerated debris-flow deposits are loose mixtures, comprising coarse and fine particles. Owing to seeping water, these fine particles are eroded and transported through the skeleton formed by the coarse particles. Such erosion can modify the porosity of deposits and influence their mechanical characteristics, which can be non-negligible for geotechnical and geological engineering. In this study, seven groups of seepage tests on gravel-sand-clay mixtures with different coarse particle content proportions (48%, 52%, 60%, 70%, 80%, 90%, and 100%) were conducted to investigate the erosion characteristics of debris-flow deposits triggered by seepage flows. In particular, concentrated leak erosion, internal instability erosion, and piping were noted in the soil with a coarse particle content of 48%-80%. Further, when the coarse particle content exceeds 80%, the soil does not disintegrate. A model coupling seepage and internal erosion was also developed to characterise internal erosion. For this model, mass conservation equations were reformulated for different types of internal erosion, based on the assumptions for the pore channel erosion of suspended materials and general erosion. Moreover, an equation based on the internal erosion rate, considering the pore size distribution and hydraulic gradient, was firstly introduced for concentrated leak and internal instability erosion. This equation could efficiently evaluate the mass of particles eroded from the soil. Lastly, the model was calibrated based on experimental data; the corresponding results are discussed herein.
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| 3. |
- Jiang, Yuchen, et al.
(författare)
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Early-age performance of lag screw shear connections for glulam-lightweight concrete composite beams
- 2017
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618. ; 151, s. 36-42
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical behavior of the shear connections has a significant influence on both the load-carrying capacity and the bending stiffness of timber-concrete composite (TCC) beams. All the studies reported so far have concentrated on the performance of TCC connections in mature concrete. The performance of shear connections for TCC beams at early concrete ages, however, has not been investigated yet. This information is essential to evaluate the structural behavior of TCC floors or bridges during construction. In this paper, a total of 18 push-out tests with concrete ages ranging from 12 h to 28 days are performed, to investigate the early-age performance of lag screw shear connections in the lightweight concrete. Development of concrete strength with time is also analyzed. At the concrete ages shorter than 7 days, both the stiffness and strength of the screw connectors increase evidently with time, which follows the same growth trend with the concrete strength. After a 7-day cure, screw shear connections reach almost 100% of both the 28-day serviceability slip modulus and shear strength. Material properties of the glulam and the screw fastener are decisive in the shear performance of connections when the concrete hardens to some degree. Based on the experimental results, the accuracy of the design methods proposed in Eurocode 5 is evaluated. In addition, by non-linear regression of the experiment data, expressions to predict the development of load-carrying capacity and serviceability slip modulus for screw shear connections before 28 days are established.
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| 4. |
- Li, Zaifang, et al.
(författare)
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A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS
- 2018
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Ingår i: Advanced Electronic Materials. - : Wiley-VCH Verlagsgesellschaft. - 2199-160X. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- A free-standing high-output power density polymeric thermoelectric (TE) device is realized based on a highly conductive (approximate to 2500 S cm(-1)) structure-ordered poly(3,4-ethylenedioxythiophene):polystyrene sulfonate film (denoted as FS-PEDOT:PSS) with a Seebeck coefficient of 20.6 mu V K-1, an in-plane thermal conductivity of 0.64 W m(-1) K-1, and a peak power factor of 107 mu W K-2 m(-1) at room temperature. Under a small temperature gradient of 29 K, the TE device demonstrates a maximum output power density of 99 +/- 18.7 mu W cm(-2), which is the highest value achieved in pristine PEDOT:PSS based TE devices. In addition, a fivefold output power is demonstrated by series connecting five devices into a flexible thermoelectric module. The simplicity of assembling the films into flexible thermoelectric modules, the low out-of-plane thermal conductivity of 0.27 W m(-1) K-1, and free-standing feature indicates the potential to integrate the FS-PEDOT:PSS TE modules with textiles to power wearable electronics by harvesting human bodys heat. In addition to the high power factor, the high thermal stability of the FS-PEDOT:PSS films up to 250 degrees C is confirmed by in situ temperature-dependent X-ray diffraction and grazing incident wide angle X-ray scattering, which makes the FS-PEDOT:PSS films promising candidates for thermoelectric applications.
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| 5. |
- Liu, Meng, et al.
(författare)
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Characterization of a trichome-specific promoter of the aldehyde dehydrogenase 1 (ALDH1) gene in Artemisia annua
- 2016
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Ingår i: Plant Cell Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 126:3, s. 469-480
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Tidskriftsartikel (refereegranskat)abstract
- Artemisinin is a frequently used anti-malaria drug extracted from glandular trichomes (GSTs) in Artemisia annua L. In this study, we report on the characterization of the promoter of aldehyde dehydrogenase 1 (ALDH1) involved in the biosynthesis of artemisinin. A 1620-bp promoter fragment was cloned upstream of the ALDH1 start codon. Putative regulatory cis-acting elements are predicted by software, revealing that this gene is affected by complex factors. The activity of the ALDH1 promoter was analyzed using a reporter gene GUS. GUS expression showed a spatial difference in leaves at different ages. In young leaves, GUS staining was exclusively discovered in GSTs. In older leaves, both GSTs and T-shaped trichomes (TSTs) showed GUS signals. Only TSTs showed GUS staining in lower leaves. No GUS staining was detected in the bottom leaves. The result demonstrates that the ALDH1 promoter is trichome-specific. The RT-Q-PCR analysis revealed that both wild-type and recombinant promoters showed similar activity in A. annua. After application of exogenous 100 μM methyl jasmonate, 100 μM gibberellin and 100 μM salicylic acid separately, the transcript levels were increased significantly, indicating that ALDH1 may play an important role in the response to hormones in A. annua.
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| 6. |
- Luo, Ziyu, et al.
(författare)
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An Efficient Deep-Subwavelength Second Harmonic Nanoantenna Based on Surface Plasmon-Coupled Dilute Nitride GaNP Nanowires
- 2021
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Ingår i: Nano Letters. - : AMER CHEMICAL SOC. - 1530-6984 .- 1530-6992. ; 21:8, s. 3426-3434
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Tidskriftsartikel (refereegranskat)abstract
- High-index semiconductor nanoantennae represent a powerful platform for nonlinear photon generation. Devices with reduced footprints are pivotal for higher integration capacity and energy efficiency in photonic integrated circuitry (PIC). Here, we report on a deep subwavelength nonlinear antenna based on dilute nitride GaNP nanowires (NWs), whose second harmonic generation (SHG) shows a 5-fold increase by incorporating similar to 0.45% of nitrogen (N), in comparison with GaP counterpart. Further integrating with a gold (Au) thin film-based hybrid cavity achieves a significantly boosted SHG output by a factor of similar to 380, with a nonlinear conversion efficiency up to 9.4 x 10(-6) W-1. In addition, high-density zinc blende (ZB) twin phases were found to tailor the nonlinear radiation profile via dipolar interference, resulting in a highly symmetric polarimetric pattern well-suited for coupling with polarization nano-optics. Our results manifest dilute nitride nanoantenna as promising building blocks for future chip-based nonlinear photonic technology.
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| 7. |
- Matias-Hernandez, Luis, et al.
(författare)
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AaMYB1 and its orthologue AtMYB61 affect terpene metabolism and trichome development in Artemisia annua and Arabidopsis thaliana
- 2017
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Ingår i: The Plant Journal. - : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 90:3, s. 520-534
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Tidskriftsartikel (refereegranskat)abstract
- The effective anti-malarial drug artemisinin (AN) isolated from Artemisia annua is relatively expensive due to the low AN content in the plant as AN is only synthesized within the glandular trichomes. Therefore, genetic engineering of A. annua is one of the most promising approaches for improving the yield of AN. In this work, the AaMYB1 transcription factor has been identified and characterized. When AaMYB1 is overexpressed in A. annua, either exclusively in trichomes or in the whole plant, essential AN biosynthetic genes are also overexpressed and consequently the amount of AN is significantly increased. Artemisia AaMYB1 constitutively overexpressing plants displayed a greater number of trichomes. In order to study the role of AaMYB1 on trichome development and other possibly connected biological processes, AaMYB1 was overexpressed in Arabidopsis thaliana. To support our findings in Arabidopsis thaliana, an AaMYB1 orthologue from this model plant, AtMYB61, was identified and atmyb61 mutants characterized. Both AaMYB1 and AtMYB61 affected trichome initiation, root development and stomatal aperture in A. thaliana. Molecular analyses indicated that two crucial trichome activator genes are misexpressed in atmyb61 mutant plants and in plants overexpressing AaMYB1. Furthermore, AaMYB1 and AtMYB61 are also essential for gibberellin (GA) biosynthesis and degradation in both species by positively affecting the expression of the enzymes that convert GA(9) into the bioactive GA(4) as well as the enzymes involved in the degradation of GA(4). Overall, these results identify AaMYB1/AtMYB61 as a key component of the molecular network that connects important biosynthetic processes, and reveal its potential value for AN production through genetic engineering.
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| 8. |
- Qian, Zhao, et al.
(författare)
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Revisiting Mg-Mg2Ni System from Electronic Perspective
- 2017
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- Both Mg and Mg2Ni are promising electrode materials in conversion-type secondary batteries. Earlier studies have shown their single-phase prospects in electro-devices, while in this work, we have quantitatively reported the electronic properties of their dual-phase materials, that is, Mg-Mg2Ni alloys, and analyzed the underlying reasons behind the property changes of materials. The hypoeutectic Mg-Mg2Ni alloys are found to be evidently more conductive than the hypereutectic Mg-Mg2Ni system. The density functional theory (DFT) calculations give the intrinsic origin of electronic structures of both Mg2Ni and Mg. The morphology of quasi-nanoscale eutectics is another factor that can affect the electronic properties of the investigated alloy system; that is, the electrical property change of the investigated alloys system is due to a combination of the intrinsic property difference between the two constituting phases and the change of eutectic microstructures that affect electron scattering. In addition, regarding the Mg-Mg2Ni alloy design for device applications, the electronic property and mechanical aspect should be well balanced.
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| 9. |
- Shen, Qian, et al.
(författare)
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The Genome of Artemisia annua Provides Insight into the Evolution of Asteraceae Family and Artemisinin Biosynthesis
- 2018
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Ingår i: Molecular Plant. - : Cell Press. - 1674-2052 .- 1752-9867. ; 11:6, s. 776-788
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Tidskriftsartikel (refereegranskat)abstract
- Artemisia annua, commonly known as sweet wormwood or Qinghao, is a shrub native to China and has long been used for medicinal purposes. A. annua is now cultivated globally as the only natural source of a potent anti-malarial compound, artemisinin. Here, we report a high-quality draft assembly of the 1.74-gigabase genome of A. annua, which is highly heterozygous, rich in repetitive sequences, and contains 63 226 protein-coding genes, one of the largest numbers among the sequenced plant species. We found that, as one of a few sequenced genomes in the Asteraceae, the A. annua genome contains a large number of genes specific to this large angiosperm clade. Notably, the expansion and functional diversification of genes encoding enzymes involved in terpene biosynthesis are consistent with the evolution of the artemisinin biosynthetic pathway. We further revealed by transcriptome profiling that A. annua has evolved the sophisticated transcriptional regulatory networks underlying artemisinin biosynthesis. Based on comprehensive genomic and transcriptomic analyses we generated transgenic A. annua lines producing high levels of artemisinin, which are now ready for large-scale production and thereby will help meet the challenge of increasing global demand of artemisinin.
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| 10. |
- Wang, Hao, et al.
(författare)
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In-situ growth of low-dimensional perovskite-based insular nanocrystals for highly efficient light emitting diodes
- 2023
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Ingår i: Light. - : SPRINGERNATURE. - 2095-5545 .- 2047-7538. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Regulation of perovskite growth plays a critical role in the development of high-performance optoelectronic devices. However, judicious control of the grain growth for perovskite light emitting diodes is elusive due to its multiple requirements in terms of morphology, composition, and defect. Herein, we demonstrate a supramolecular dynamic coordination strategy to regulate perovskite crystallization. The combined use of crown ether and sodium trifluoroacetate can coordinate with A site and B site cations in ABX(3) perovskite, respectively. The formation of supramolecular structure retard perovskite nucleation, while the transformation of supramolecular intermediate structure enables the release of components for slow perovskite growth. This judicious control enables a segmented growth, inducing the growth of insular nanocrystal consist of low-dimensional structure. Light emitting diode based on this perovskite film eventually brings a peak external quantum efficiency up to 23.9%, ranking among the highest efficiency achieved. The homogeneous nano-island structure also enables high-efficiency large area (1 cm(2)) device up to 21.6%, and a record high value of 13.6% for highly semi-transparent ones.
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