| 1. |
- Zhao, Yanyan, et al.
(författare)
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A 30,000-km journey by Apus apus pekinensis tracks arid lands between northern China and south-western Africa
- 2022
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Ingår i: Movement Ecology. - : Springer Science and Business Media LLC. - 2051-3933. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: As a widely distributed and aerial migratory bird, the Common Swift (Apus apus) flies over a wide geographic range in Eurasia and Africa during migration. Although some studies have revealed the migration routes and phenology of European populations, A. a. apus (from hereon the nominate apus), the route used by its East Asian counterpart A. a. pekinensis (from hereon pekinensis) remained a mystery. Methods: Using light level geolocators, we studied the migration of adult pekinensis breeding in Beijing from 2014 to 2018, and analysed full annual tracks obtained from 25 individuals. In addition, we used the mean monthly precipitation to assess the seasonal variations in humidity for the distribution ranges of the nominate apus and pekinensis. This environmental variable is considered to be critically relevant to their migratory phenology and food resource abundance. Results: Our results show that the swifts perform a round-trip journey of ca 30,000 km each year, representing a detour of 26% in autumn and 15% in spring compared to the shortest route between the breeding site in Beijing and wintering areas in semi-arid south-western Africa. Compared to the nominate apus, pekinensis experiences drier conditions for longer periods of time. Remarkably, individuals from our study population tracked arid habitat along the entire migration corridor leading from a breeding site in Beijing to at least central Africa. In Africa, they explored more arid habitats during non-breeding than the nominate apus. Conclusions: The migration route followed by pekinensis breeding in Beijing might suggest an adaptation to semi-arid habitat and dry climatic zones during non-breeding periods, and provides a piece of correlative evidence indicating the historical range expansion of the subspecies. This study highlights that the Common Swift may prove invaluable as a model species for studies of migration route formation and population divergence.
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| 2. |
- Golub, Malgorzata, et al.
(författare)
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A framework for ensemble modelling of climate change impacts on lakes worldwide : the ISIMIP Lake Sector
- 2022
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Ingår i: Geoscientific Model Development. - : Copernicus Publications. - 1991-959X .- 1991-9603. ; 15:11, s. 4597-4623
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Tidskriftsartikel (refereegranskat)abstract
- Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure and resulting changes in lake biogeochemistry in order to plan for the likely impacts. Previous studies of the impacts of climate change on lakes have often relied on a single model forced with limited scenario-driven projections of future climate for a relatively small number of lakes. As a result, our understanding of the effects of climate change on lakes is fragmentary, based on scattered studies using different data sources and modelling protocols, and mainly focused on individual lakes or lake regions. This has precluded identification of the main impacts of climate change on lakes at global and regional scales and has likely contributed to the lack of lake water quality considerations in policy-relevant documents, such as the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Here, we describe a simulation protocol developed by the Lake Sector of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) for simulating climate change impacts on lakes using an ensemble of lake models and climate change scenarios for ISIMIP phases 2 and 3. The protocol prescribes lake simulations driven by climate forcing from gridded observations and different Earth system models under various representative greenhouse gas concentration pathways (RCPs), all consistently bias-corrected on a 0.5 degrees x 0.5 degrees global grid. In ISIMIP phase 2, 11 lake models were forced with these data to project the thermal structure of 62 well-studied lakes where data were available for calibration under historical conditions, and using uncalibrated models for 17 500 lakes defined for all global grid cells containing lakes. In ISIMIP phase 3, this approach was expanded to consider more lakes, more models, and more processes. The ISIMIP Lake Sector is the largest international effort to project future water temperature, thermal structure, and ice phenology of lakes at local and global scales and paves the way for future simulations of the impacts of climate change on water quality and biogeochemistry in lakes.
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| 3. |
- Shangguan, Zhichun, et al.
(författare)
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A rechargeable molecular solar thermal system below 0 °C
- 2022
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6539 .- 2041-6520. ; 13:23, s. 6950-6958
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Tidskriftsartikel (refereegranskat)abstract
- An optimal temperature is crucial for a broad range of applications, from chemical transformations, electronics, and human comfort, to energy production and our whole planet. Photochemical molecular thermal energy storage systems coupled with phase change behavior (MOST-PCMs) offer unique opportunities to capture energy and regulate temperature. Here, we demonstrate how a series of visible-light-responsive azopyrazoles couple MOST and PCMs to provide energy capture and release below 0 degrees C. The system is charged by blue light at -1 degrees C, and discharges energy in the form of heat under green light irradiation. High energy density (0.25 MJ kg(-1)) is realized through co-harvesting visible-light energy and thermal energy from the environment through phase transitions. Coatings on glass with photo-controlled transparency are prepared as a demonstration of thermal regulation. The temperature difference between the coatings and the ice cold surroundings is up to 22.7 degrees C during the discharging process. This study illustrates molecular design principles that pave the way for MOST-PCMs that can store natural sunlight energy and ambient heat over a wide temperature range.
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| 4. |
- Wang, Yuwen, et al.
(författare)
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Fast room-temperature hydrogenation of nitroaromatics on Pd nanocrystal-boron cluster/graphene oxide nanosheets
- 2022
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Ingår i: Molecular Catalysis. - : Elsevier. - 2468-8231. ; 529
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of nitroaromatics to aminoaromatics is essential for fine chemical production and effective sewage treatment. However, the activity of an external catalyst is essential for the reaction. In this study, Pd nanocrystals were anchored in situ on two-dimensional graphene oxide (GO), which acted as a catalyst support with high specific surface area. The oxygen-containing groups on the surface of GO bonded to the functionally rich boron clusters through hydrogen bonding interactions. A mildly reducible closed-dodecahydrododecaboric acid anion cluster (closo‑[B12H12]2–) was employed as the target site. The mild reducibility of closo‑[B12H12]2– resulted in a wide dispersion of ultrafine Pd nanocrystals on GO. Under ambient conditions, Pd/BGO rapidly hydrogenated nitroaromatics, such as 4-nitrophenol, to aminoaromatics with approximately 100% efficiency. Moreover, Pd/BGO retained its high catalytic activity for the hydrogenation/reduction of 4-nitrophenol after five catalytic cycles. Therefore, Pd/BGO could be a promising and economically viable candidate for various practical applications. The proposed innovative preparation strategy and highly efficient catalytic activity suggested the effective performance of closo‑[B12H12]2– as nanometal nucleation target sites. In addition to providing an alternate route for preparing supported nanometals, this study presents a stable and efficient catalyst for the hydrogenation of nitroaromatics.
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| 5. |
- Zhao, Yi, et al.
(författare)
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Improved Proton Adsorption and Charge Separation on Cadmium Sulfides for Photocatalytic Hydrogen Production
- 2022
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Ingår i: Energy Technology. - : John Wiley & Sons. - 2194-4288 .- 2194-4296. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.
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| 6. |
- Fang, K., et al.
(författare)
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Wind speed reconstruction from a tree-ring difference index in northeastern Inner Mongolia
- 2022
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 72
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Tidskriftsartikel (refereegranskat)abstract
- The lack of instrumental wind speed data beyond the industrial era limits our ability to evaluate the contributions of natural versus anthropogenic processes on long-term changes in wind speed. It is thus desirable to find proxies for historical changes in wind speed. Persistent and strong winds can cause compression wood composed of wider and denser rings in conifer trees at leeward sides. This work hypothesizes that the asymmetric wind impact on tree radial growth provides information about wind speed changes. To test the hypothesis, we developed a Tree-Ring Difference Index (TRDI) representing the differences between tree ring widths at the windward and leeward sides. Thirty-four trees subjected to strong and persistent winds in a Picea mongolica forest in northeastern Inner Mongolia were analyzed. The TRDI based on 124 cores correlates significantly with the maximum wind speeds recorded from May to August, indicating that this proxy can be used for wind speed reconstruction. Our reconstruction reveals long-term changes in wind speed including an upward trend from 1940 to 1954, followed by continually decreasing wind speeds from 1955 to 1990 and increasing values from 1991 to 2010. The reconstructed wind speeds include strong multi-decadal variability and significant correlations with the Pacific Decadal Oscillation (PDO). © 2022 Elsevier GmbH
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| 7. |
- Zhou, F. F., et al.
(författare)
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Teleconnections between large-scale oceanic-atmospheric patterns an interannual surface wind speed variability across China: Regional and seasonal patterns
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 838
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Tidskriftsartikel (refereegranskat)abstract
- Great attention has been paid to the long-term decline in terrestrial near-surface wind speed (SWS) in China. However, how the SWS varies with regions and seasons and what modulates these changes remain unclear. Based on quality-controlled and homogenized terrestrial SWS data from 596 stations, the covarying SWS patterns during the Asian Summer Monsoon (ASM) and the Asian Winter Monsoon (AWM) seasons are defined for China using empirical orthogonal function (EOF) analysis for 1961-2016. The dominant SWS features represented by EOF1 patterns in both seasons show a clear decline over most regions of China. The interannual variability of the EOF1 patterns is closely related to the Northeast Asia Low Pressure (NFAIP) and the Arctic Oscillation (AO), respectively. The EOF2 and EOF3 patterns during ASM (AWM) season describe a dipole mode of SWS between Fast Tibetan Plateau and Fast China Plain (between Fast Tibetan Plateau and Northeast China), and between Southeast and Northeast China (between Northeast China and the coastal areas of Southeast China), respectively. These dipole structures of SWS changes arc closely linked with the oceanic-atmospheric oscillations on interannual scale.
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| 8. |
- Liu, Wei, et al.
(författare)
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Coherent dynamics of multi-spin V-B(-) center in hexagonal boron nitride
- 2022
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Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Hexagonal boron nitride (hBN) has recently been demonstrated to contain optically polarized and detected electron spins that can be utilized for implementing qubits and quantum sensors in nanolayered-devices. Understanding the coherent dynamics ofmicrowave driven spins in hBN is of crucial importance for advancing these emerging new technologies. Here, we demonstrate and study the Rabi oscillation and related phenomena of a negatively charged boron vacancy (V-B(-)) spin ensemble in hBN. We report on different dynamics of the V-B(-) spins at weak and strong magnetic fields. In the former case the defect behaves like a single electron spin system, while in the latter case it behaves like a multi-spin system exhibiting multiple-frequency dynamical oscillation as beat in the Ramsey fringes. We also carry out theoretical simulations for the spin dynamics of V-B(-) and reveal that the nuclear spins can be driven via the strong electron nuclear coupling existing in V-B(-) center, which can be modulated by the magnetic field and microwave field.
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| 9. |
- Lv, Jiezhao, et al.
(författare)
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Numerical Investigation of the Stimulated Growth of Single-Crystal Fibers by Point-Effect-Induced Fluid Dynamics
- 2022
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 22:12, s. 7031-7039
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Tidskriftsartikel (refereegranskat)abstract
- Using molecular dynamics analysis and a two-component diffusion model that accounts for the time-dependent crystal surface chemical reaction, we show by extensive numerical simulations that the recently observed prismatic facet growth suppression in single-crystal fibers is the combined action of self-shielding by crystal surface selectivity and self-channeling arising from a point effect due to fibers small diameters and large aspect ratios. We further show that the self-channeling leads to a pyramidal-face-aiming solute flow, resulting in accelerated single-crystal fiber growth. This mesoscopic stimulated matter growth acceleration theory can satisfactorily explain all experimental results reported to date. This new crystal fiber growth technology opens a realm of application possibilities for single-crystal fiber architectures in chip-size photonics.
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| 10. |
- Pan, Qinying, et al.
(författare)
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Ultrafast charge transfer dynamics in 2D covalent organic frameworks/Re-complex hybrid photocatalyst
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Rhenium(I)-carbonyl-diimine complexes have emerged as promising photocatalysts for carbon dioxide reduction with covalent organic frameworks recognized as perfect sensitizers and scaffold support. Such Re complexes/covalent organic frameworks hybrid catalysts have demonstrated high carbon dioxide reduction activities but with strong excitation energy-dependence. In this paper, we rationalize this behavior by the excitation energy-dependent pathways of internal photo-induced charge transfer studied via transient optical spectroscopies and time-dependent density-functional theory calculation. Under band-edge excitation, the excited electrons are quickly injected from covalent organic frameworks moiety into catalytic RheniumI center within picosecond but followed by fast backward geminate recombination. While under excitation with high-energy photon, the injected electrons are located at high-energy levels in RheniumI centers with longer lifetime. Besides those injected electrons to RheniumI center, there still remain some long-lived electrons in covalent organic frameworks moiety which is transferred back from RheniumI. This facilitates the two-electron reaction of carbon dioxide conversion to carbon monoxide.
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