| 1. |
- Chen, Aifang, 1990, et al.
(författare)
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Rising future tropical cyclone-induced extreme winds in the Mekong River Basin
- 2020
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273 .- 2095-9281. ; 65:5, s. 419-424
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Science China Press The societal impact of extreme winds induced by tropical cyclones (TCs) is a major concern in the Mekong River Basin (MRB). Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed since the 1970s, climate models project an increasing TC intensity in the 21st century over the Western North Pacific, which is the primary TC source region influencing the MRB. Yet, how future TC activities will affect extreme winds quantitatively in the MRB remains unclear. By employing a novel dynamical downscaling technique using a specialized, coupled ocean-atmospheric model, shorter return periods of maximum wind speed in the MRB for 2081–2100 compared with 1981–2000 are projected based on five global climate models under the RCP8.5 scenario, suggesting increases in the future tropical cyclone intensity. The results point to consistently elevated future TC-related risks that may jeopardize sustainable development, disrupt food supply, and exacerbate conflicts in the region and beyond.
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| 2. |
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| 5. |
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| 6. |
- YanHui, Fan, et al.
(författare)
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The rates and patterns of insertions, deletions and substitutions in mouse and rat inferred from introns
- 2008
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Ingår i: Chinese Science Bulletin. - : Elsevier BV. - 1001-6538 .- 1861-9541 .- 2095-9273 .- 2095-9281. ; 53:18, s. 2813-2819
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Tidskriftsartikel (refereegranskat)abstract
- The rates and patterns of InDel (insertions and deletions) and substitution in rodent (mouse and rat) have been studied. The result reveals that deletions occur more frequently than insertions, and single nucleotide insertion and deletion are the most frequent in both mouse and rat. The frequencies of both deletions and insertions decrease rapidly with increasing InDels length, and the size distributions of both insertions and deletions can be described well by power-law. There are more AT-->G than GC-->AT substitutions in the introns of rat. However, there are more GC-->AT than AT-->GC substitutions in the introns in mouse. The deletion bias found in introns in mouse and rat supports the prediction that intron insertions are more deleterious than deletions because of reduced transcription and splicing efficiency. The patterns of substitution suggest that both composition and GC content are not equilibrium in the introns in rodents.
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| 7. |
- Zhang, Wenhua, 1981-, et al.
(författare)
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Density Functional Study on the Mechanism of CO Oxidation with Activated Water on O/Au(111) Surface
- 2009
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Ingår i: Chinese Science Bulletin. - : Elsevier BV. - 1001-6538 .- 1861-9541 .- 2095-9273 .- 2095-9281. ; 54:11, s. 1973-1977
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Tidskriftsartikel (refereegranskat)abstract
- With density functional theory, the mechanism of water-enhanced CO oxidation on oxygen pre-covered Au (111) surface is theoretically studied. First, water is activated by the pre-covered oxygen atom and dissociates to OHads group. Then, OHads reacts with COads to form chemisorbed HOCOads. Finally, with the aid of water, HOCO ads dissociates to CO2. The whole process can be described as 1/2H2O ads + H2Oads + 1/2O ads + COads → H3Oads + CO 2, gas. One CO2 is formed with only 1/2 pre-covered oxygen atom. That is why more CO2 is observed when water is present on oxygen pre-covered Au (111) surface. Activation energy of each elementary step is low enough to allow the reaction to proceed at low temperature
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| 8. |
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| 9. |
- Aaij, R., et al.
(författare)
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Measurement of the lifetimes of promptly produced Omega(0)(c) and Xi(9)(c) baryons
- 2022
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Ingår i: Science Bulletin. - : Elsevier. - 2095-9273. ; 67:5, s. 479-487
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Tidskriftsartikel (refereegranskat)abstract
- A measurement of the lifetimes of the Omega(0)(c) and Xi(0)(c) baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb(-1) collected by the LHCb experiment. The Omega(0)(c) and Xi(0)(c) baryons are produced directly from proton interactions and reconstructed in the pK(-)K(-)pi(+) final state. The Omega(0)(c) lifetime is measured to be 276.5 +/- 13.4 +/- 4.4 +/- 0.7 fs, and the Xi(0)(c) lifetime is measured to be 148.0 +/- 2.3 +/- 2.2 +/- 0.2 fs, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the D-0 lifetime. These results confirm previous LHCb measurements based on semileptonic beauty-hadron decays, which disagree with earlier results of a four times shorter Omega(c)0 lifetime, and provide the single most precise measurement of the Omega(0 )(c)lifetime.
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| 10. |
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| 11. |
- Büntgen, Ulf, et al.
(författare)
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Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE
- 2022
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 67:22, s. 2336-2344
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Tidskriftsartikel (refereegranskat)abstract
- Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89 Blue Rings (lack of cell wall lignification), nine Frost Rings (cell deformation and collapse), and 93 Light Rings (reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and 548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.
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| 12. |
- Chen, Jie, et al.
(författare)
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Reconciling East Asia's mid-Holocene temperature discrepancy through vegetation-climate feedback
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Ingår i: Science Bulletin. - 2095-9273.
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Tidskriftsartikel (refereegranskat)abstract
- The term “Holocene temperature conundrum” refers to the inconsistencies between proxy-based reconstructions and transient model simulations, and it challenges our understanding of global temperature evolution during the Holocene. Climate reconstructions indicate a cooling trend following the Holocene Thermal Maximum, while model simulations indicate a consistent warming trend due to ice-sheet retreat and rising greenhouse gas concentrations. Various factors, such as seasonal biases and overlooked feedback processes, have been proposed as potential causes for this discrepancy. In this study, we examined the impact of vegetation-climate feedback on the temperature anomaly patterns in East Asia during the mid-Holocene (∼6 ka). By utilizing the fully coupled Earth system model EC-Earth and performing simulations with and without coupled dynamic vegetation, our objective was to isolate the influence of vegetation changes on regional temperature patterns. Our findings reveal that vegetation-climate feedback contributed to warming across most of East Asia, resulting in spatially diverse temperature changes during the mid-Holocene and significantly improved model-data agreement. These results highlight the crucial role of vegetation-climate feedback in addressing the Holocene temperature conundrum and emphasize its importance for simulating accurate climate scenarios.
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| 13. |
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| 15. |
- Fang, Tao, et al.
(författare)
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Perovskite QLED with an external quantum efficiency of over 21% by modulating electronic transport
- 2021
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Ingår i: Science Bulletin. - : ELSEVIER. - 2095-9273. ; 66:1, s. 36-43
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
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| 16. |
- Gao, K., et al.
(författare)
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Surface energy budget diagnosis reveals possible mechanism for the different warming rate among Earth's three poles in recent decades
- 2019
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 64:16, s. 1140-1143
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic, Antarctic and Tibetan Plateau (TP) are pivotal and sensitive areas of global climate change. Based on two reanalysis datasets during 1980–2017 with in situ observational verification, here we investigate the surface temperature (Ts) changes in these regions and the possible reasons by diagnosing the surface energy balance equation. In recent decades, the Ts of the Arctic and the TP exhibit much larger warming rates compared with the global average. Meanwhile, a weak warming trend can be detected in the Antarctic continent, accompanied by a slight cooling trend in the surrounding ocean. In the Arctic and TP, clear-sky downward long-wave radiation (LW) affected by atmospheric water vapor is the dominant factor regulating the Ts change, whereas the change in sea ice played an important role in modulating the Ts over the polar seas efficiently via influencing the ice albedo feedback and sea surface heat storage capacity. © 2019 Science China Press
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| 17. |
- He, Yong, et al.
(författare)
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Release characteristic of different classes of sodium during combustion of Zhun-Dong coal investigated by laser-induced breakdown spectroscopy
- 2015
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 60:22, s. 1927-1934
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Tidskriftsartikel (refereegranskat)abstract
- Serious fouling and slagging problems are associated with the combustion of Chinese Zhun-Dong coal due to its high content of sodium (Na). Understanding the release characteristic of Na during the combustion is essential to viable utilization of this coal. In this work, coal samples were treated with a sequence of solvents: water (H2O), ammonium acetate (NH4Ac), hydrochloric acid (HCl), and the release characteristics of various classes of Na during coal combustion were investigated using the technique of laser-induced breakdown spectroscopy. The relative contribution of various Na classes to the Na release during each combustion stage was found to be similar, in the order of H2O-soluble Na > NH4Ac-soluble Na > HCl-soluble Na > insoluble Na. Sodium released during the devolatilization stage can be attributed to each of the sodium classes. After the devolatilization stage, H2O-soluble Na and NH4Ac-soluble Na dominated the Na release during both char and ash stages. Over 64 % of the total Na released during combustion comes from the H2O-soluble Na, which suggests that the Na release during the combustion of Zhun-Dong coal can be reduced effectively after treatment by H2O washing.
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| 18. |
- Jia, Xue, et al.
(författare)
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CsPb(IxBr1-x)(3) solar cells
- 2019
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Ingår i: Science Bulletin. - : ELSEVIER. - 2095-9273. ; 64:20, s. 1532-1539
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Tidskriftsartikel (refereegranskat)abstract
- Owing to its nice performance, low cost, and simple solution-processing, organic-inorganic hybrid perovskite solar cell (PSC) becomes a promising candidate for next-generation high-efficiency solar cells. The power conversion efficiency (PCE) has boosted from 3.8% to 25.2% over the past ten years. Despite the rapid progress in PCE, the device stability is a key issue that impedes the commercialization of PSCs. Recently, all-inorganic cesium lead halide perovskites have attracted much attention due to their better stability compared with their organic-inorganic counterpart. In this progress report, we summarize the properties of CsPb(IxBr1-x)(3) and their applications in solar cells. The current challenges and corresponding solutions are discussed. Finally, we share our perspectives on CsPb(IxBr1-x)(3) solar cells and outline possible directions to further improve the device performance. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
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| 19. |
- Li, Zhuwei, et al.
(författare)
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Engineering single-atom active sites anchored covalent organic frameworks for efficient metallaphotoredox C-N cross-coupling reactions
- 2022
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 67:19, s. 1971-1981
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Tidskriftsartikel (refereegranskat)abstract
- Photoredox catalysis has become an indispensable solution for the synthesis of small organic molecules. However, the precise construction of single-atomic active sites not only determines the catalytic performance, but also avails the understanding of structure-activity relationship. Herein, we develop a facile approach to immobilize single-atom Ni sites anchored porous covalent organic framework (COF) by use of 4,40,400-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,6-diformylpyridine (Ni SAS/TD-COF). Ni SAS/TDCOF catalyst achieves excellent catalytic performance in visible-light-driven catalytic carbon-nitrogen cross-coupling reaction between aryl bromides and amines under mild conditions. The reaction provides amine products in excellent yields (71%-97%) with a wide range of substrates, including aryl and heteroaryl bromides with electron-deficient, electron-rich and neutral groups. Notably, Ni SAS/TD-COF could be recovered from the reaction mixture, corresponding to the negligible loss of photoredox performance after several cycles. This work provides a promising opportunity upon rational design of single-atomic active sites on COFs and the fundamental insight of photoredox mechanism for sustainable organic transformation.
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| 20. |
- Liang, E. Y., et al.
(författare)
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Strong link between large tropical volcanic eruptions and severe droughts prior to monsoon in the central Himalayas revealed by tree-ring records
- 2019
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 64:14, s. 1018-1023
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Tidskriftsartikel (refereegranskat)abstract
- Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomalies. Using a tree-ring network of precisely dated Himalayan birch in the central Himalayas, we reconstructed variations in the regional pre-monsoon precipitation back to 1650 CE. A superposed epoch analysis indicates that the pre-monsoon regional droughts are associated with large tropical volcanic eruptions, appearing to have a strong influence on hydroclimatic conditions in the central Himalayas. In fact, the most severe drought since 1650 CE occurred after the Tambora eruption. These results suggest that dry conditions prior to monsoon in the central Himalayas were associated with explosive tropical volcanism. Prolonged La Nina events also correspond with persistent pre-monsoon droughts in the central Himalayas. Our results provide evidence that large tropical volcanic eruptions most likely induced severe droughts prior to monsoon in the central Himalayas. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
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| 21. |
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| 26. |
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| 27. |
- Wang, Shuai, et al.
(författare)
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Alignment of social and ecological structures increased the ability of river management
- 2019
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 64:18, s. 1318-1324
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Tidskriftsartikel (refereegranskat)abstract
- Large hydrologic basins involve multiple stakeholders, and coupled dynamic social and ecological processes. Managing such basins has long been a challenge. Balancing the demand for water from nature against that from humans is always difficult, particularly in arid watersheds. Here, we analyze potential institutional causes of ecological degradation and how it can be reversed by introducing new forms of governance. The framework and assumptions are illustrated using China's second-largest endorheic basin, where empirical evidence shows that the introduction of a new governing authority connecting midstream and downstream actors facilitated the establishment of a new governance regime that is better aligned with the biophysical scales of the watershed. A trans-regional water allocation project initiated by the new higher-level authority successfully rescued downstream oases and restored a dried terminal lake. These outcomes suggest that when social and ecological structures are better aligned our ability to manage the interplay between social and ecological processes increases. However, the lack of direct connection between the actors of the middle and lower reaches resulted in the paradox of an increase in water demand. We therefore suggest that measures to stimulate the emergence of horizontal social ties linking different critical groups of actors across the watershed could further the alignment of the institutional and biophysical structures-without these changes sustainable management of river basins and other common pool resources will remain problematic.
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| 28. |
- Xu, Min, et al.
(författare)
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Solid Oxide Fuel Cell Interconnect Design Optimization considering the Thermal Stresses
- 2016
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 61:17, s. 1333-1344
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical failure of solid oxide fuel cell (SOFC) components may cause cracks with consequences such as gas leakage, structure instability and reduction of cell lifetime. A comprehensive 3D model of the thermal stresses of an anode-supported planar SOFC is presented in this work. The main objective of this paper is to get an interconnect optimized design by evaluating the thermal stresses of an anode-supported SOFC for different designs, which would be a new criterion for interconnect design. The model incorporates the momentum, mass, heat, ion and electron transport, as well as steady-state mechanics. Heat from methane steam reforming and water–gas shift reaction were considered in our model. The results examine the relationship between the interconnect structures and thermal stresses in SOFC at certain mechanical properties. A wider interconnect of the anode side lowers the stress obviously. The simulation results also indicate that thermal stress of coflow design is smaller than that of counterflow, corresponding to the temperature distribution. This study shows that it is possible to design interconnects for an optimum thermal stress performance of the cell.
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| 29. |
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