| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Dou, Yujie, et al.
(författare)
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Reliability of using vegetation optical depth for estimating decadal and interannual carbon dynamics
- 2023
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- Vegetation optical depth (VOD) from satellite passive microwave sensors has enabled monitoring of aboveground biomass carbon dynamics by building a relationship with static carbon maps over space and then applying this relationship to VOD time series. However, uncertainty in this relationship arises from changes in water stress, as VOD is mainly determined by vegetation water content, which varies at diurnal to interannual scales, and depends on changes in both biomass and relative moisture content. Here, we studied the reliability of using VOD from various microwave frequencies and temporal aggregation methods for estimating decadal biomass carbon dynamics at the global scale. We used the VOD diurnal variations to represent the magnitude of vegetation water content buffering caused by climatic variations for a constant amount of dry biomass carbon. This magnitude of VOD diurnal variations was then used to evaluate the likelihood of VOD decadal variations in reflecting decadal dry biomass carbon changes. We found that SMOS-IC L-VOD and LPDR X-VOD can be reliably used to estimate decadal carbon dynamics for 76.7% and 69.9% of the global vegetated land surface, respectively, yet cautious use is warranted for some areas such as the eastern Amazon rainforest. Moreover, the annual VOD aggregated from the 95% percentile of the nighttime VOD retrievals was proved to be the most suitable parameter for estimating decadal biomass carbon dynamics among the temporal aggregation methods. Finally, we validated the use of annual VOD for estimating interannual carbon dynamics by comparing VOD changes between adjacent years against eddy covariance estimations of gross primary production from flux sites over several land cover classes across the globe. Despite the large difference in spatial scales between them, the positive correlation obtained supports the capability of satellite VOD in quantifying interannual carbon dynamics.
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| 3. |
- Fukui, Akihiko, et al.
(författare)
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TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf
- 2022
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Ingår i: Publication of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 2053-051X .- 0004-6264. ; 74:1, s. L1-L8
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of TO1-2285b, a sub-Neptune-sized planet transiting a nearby (42 pc) M dwarf with a period of 27.3 d. We identified the transit signal from the Transiting Exoplanet Survey Satellite photometric data, which we confirmed with ground-based photometric observations using the multiband imagers MuSCAT2 and MuSCAT3. Combining these data with other follow-up observations including high-resolution spectroscopy with the Tillinghast Reflector Echelle Spectrograph, high-resolution imaging with the SPeckle Polarimeter, and radial velocity (RV) measurements with the InfraRed Doppler instrument, we find that the planet has a radius of 1.74 +/- 0.08 R-circle plus, a mass of <19.5 M-circle plus + (95% c.I.), and an insolation flux of 1.54 +/- 0.14 times that of the Earth. Although the planet resides just outside the habitable zone for a rocky planet, if the planet harbors an H2O layer under a hydrogen-rich atmosphere, then liquid water could exist on the surface of the H2O layer depending on the planetary mass and water mass fraction. The bright host star in the near-infrared (K-s = 9.0) makes this planet an excellent target for further RV and atmospheric observations to improve our understanding of the composition, formation, and habitability of sub-Neptune-sized planets.
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| 4. |
- Sun, Huiliang, et al.
(författare)
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Reducing energy loss via tuning energy levels of polymer acceptors for efficient all-polymer solar cells
- 2020
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1869-1870 .- 1674-7291. ; 63:12, s. 1785-1792
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Tidskriftsartikel (refereegranskat)abstract
- The open-circuit voltage (Voc) of all-polymer solar cells (all-PSCs) is typically lower than 0.9 V even for the most efficient ones. Large energy loss is the main reason for limiting Voc and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital (LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer (CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 10% while maintaining a large Voc of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with large Voc and drives the further development of all-PSCs.
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| 5. |
- Sun, Huiliang, et al.
(författare)
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Reducing energy lossviatuning energy levels of polymer acceptors for efficient all-polymer solar cells
- 2020
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Ingår i: Science China Chemistry. - : Science China Press and Springer-Verlag GmbH Germany. - 1674-7291 .- 1869-1870. ; 63, s. 1785-1792
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Tidskriftsartikel (refereegranskat)abstract
- The open-circuit voltage (V-oc) of all-polymer solar cells (all-PSCs) is typically lower than 0.9 V even for the most efficient ones. Large energy loss is the main reason for limitingV(oc)and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital (LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer (CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 10% while maintaining a largeV(oc)of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with largeV(oc)and drives the further development of all-PSCs.
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| 6. |
- Tang, Xiaopeng, et al.
(författare)
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A novel framework for Lithium-ion battery modeling considering uncertainties of temperature and aging
- 2019
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 180, s. 162-170
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Tidskriftsartikel (refereegranskat)abstract
- Temperature and cell aging are two major factors that influence the reliability and safety of Li-ion batteries. A general battery model considering both temperature and degradation is often difficult to develop, given the fact that there are many different types of cells with different shapes and/or internal chemical components. In response, a migration-based framework is proposed in this paper for battery modeling, in which the effects of temperature and aging are treated as uncertainties. An accurate model for a fresh cell is established first and then migrated to the degraded batteries through a Bayes Monte Carlo method. Experiments are carried out on both LiFePO4 batteries and Li(Ni1/3Co1/3Mn1/3) O2 batteries under various ambient temperatures and aging levels. The results indicate that the typical voltage prediction error can be limited within ±20 mV, for the cases of temperature change up to 40 °C, and capacity degradation up to 20%. The proposed method paves ways to an effective battery management and energy control for electric vehicles or micro grid applications.
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| 7. |
- Tang, Xiaopeng, et al.
(författare)
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Run-to-Run Control for Active Balancing of Lithium Iron Phosphate Battery Packs
- 2020
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 35:2, s. 1499-1512
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Tidskriftsartikel (refereegranskat)abstract
- © 1986-2012 IEEE. Lithium iron phosphate battery packs are widely employed for energy storage in electrified vehicles and power grids. However, their flat voltage curves rendering the weakly observable state of charge are a critical stumbling block for charge equalization management. This paper focuses on the real-time active balancing of series-connected lithium iron phosphate batteries. In the absence of accurate in situ state information in the voltage plateau, a balancing current ratio (BCR) based algorithm is proposed for battery balancing. Then, BCR-based and voltage-based algorithms are fused, responsible for the balancing task within and beyond the voltage plateau, respectively. The balancing process is formulated as a batch-based run-to-run control problem, as the first time in the research area of battery management. The control algorithm acts in two timescales, including timewise control within each batch run and batchwise control at the end of each batch. Hardware-in-the-loop experiments demonstrate that the proposed balancing algorithm is able to release 97.1% of the theoretical capacity and can improve the capacity utilization by 5.7% from its benchmarking algorithm. Furthermore, the proposed algorithm can be coded in C language with the binary code in 118 328 bytes only and, thus, is readily implementable in real time.
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| 8. |
- Wang, Kai, et al.
(författare)
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Zinc anode based alkaline energy storage system: Recent progress and future perspectives of zinc–silver battery
- 2024
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Ingår i: Energy Storage Materials. - 2405-8297. ; 69
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Forskningsöversikt (refereegranskat)abstract
- Rechargeable zinc-based batteries have come to the forefront of energy storage field with a surprising pace during last decade due to the advantageous safety, abundance and relatively low cost, making them important supplements of lithium-ion batteries. As a significant role in zinc-based batteries, zinc-silver battery owns the advantages of high specific energy density, stable working voltage, high charging efficiency, safety and environmental friendliness, and it has been widely used in military such as in aerospace, deep water manned and civil field such as energy supply for watch and hearing aid. However, it is still suffering from a few drawbacks such as unsatisfactory cycle life, low utilization of the cathode. This review introduces the basic principles of zinc-silver batteries and elaborates the battery configurations aiming to understand its working mechanisms as well as the related issues. Most importantly, the very recent research updates and the concerns have arisen in the development are summarized from conventional cell to flexible device and hybrid device. Finally, the challenges and perspectives of zinc-silver batteries are further prospected to give a broad idea to readers new in the area and trigger inspirations for motivated researchers to further widen the utilization of silver-zinc batteries.
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| 9. |
- Zou, Linqing, et al.
(författare)
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Assessing the upper elevational limits of vegetation growth in global high-mountains
- 2023
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- The upper elevational limits of vegetation growth in global high-mountains have been the focus for monitoring and assessment of climate change impacts on terrestrial ecosystems. However, existing studies have relied on field surveys that do not allow for large-scale analysis. Although remote sensing data have been used for local and regional monitoring of the vegetation upper boundaries, a global synthesis of the treeline and vegetation line (the upper altitudinal threshold for the existence of trees and the transition line from vegetation to bare land or permanent snow cover, respectively) in high-mountain ecosystems is still missing. To fill this gap, we developed two independent methods based on (1) the relationship between a Sentinel-2 vegetation index and elevation and (2) the European Space Agency's 10 m resolution land cover dataset (WorldCover), respectively, to automatically identify the upper elevational limits of treeline and vegetation line for each one-quarter degree grid across the global high-mountain areas. We obtained highly consistent results from the two methods, both of which are spatially consistent with ground surveyed treeline elevations. Our results are in line with the current understanding of the global distributions of tree and vegetation lines, which are observed at the highest elevations in the Tibetan plateau and decreasing for increasing latitudes. We find that the tree and vegetation lines are aspect-dependent, reaching higher elevations on the equatorial-facing slopes than on the polar-facing slopes in high latitudes, and the opposite in the middle latitudes. Our analysis shows that mountain height is the dominant factor in determining the upper elevational limits of tree and vegetation lines across the globe, while climatic conditions and soil properties also play important roles at regional scales. Our study provides a framework for monitoring the tree and vegetation lines in global high-mountains and provides an important benchmark for further examining their long-term changes in response to climate change.
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| 10. |
- Zou, Yatao, et al.
(författare)
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Boosting Perovskite Light-Emitting Diode Performance via Tailoring Interfacial Contact
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:28, s. 24320-24326
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Tidskriftsartikel (refereegranskat)abstract
- Solution-processed perovskite light-emitting diodes (LEDs) have attracted wide attention in the past several years. However, the overall efficiency and stability of perovskite-based LEDs remain inferior to those of organic or quantum dot LEDs. Nonradiative charge recombination and the unbalanced charge injection are two critical factors that limit the device efficiency and operational stability of perovskite LEDs. Here, we develop a strategy to modify the interface between the hole transport layer and the perovskite emissive layer with an amphiphilic conjugated polymer of poly[(9,9-bis(3-(N,N-dimethylamino)propy1)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN). We show evidences that PFN improves the quality of the perovskite film, which effectively suppresses nonradiative recombination. By further improving the charge injection balance rate, a green perovskite LED with a champion current efficiency of 45.2 cd/A, corresponding to an external quantum efficiency of 14.4%, is achieved. In addition, the device based on the PFN layer exhibits improved operational lifetime. Our work paves a facile way for the development of efficient and stable perovskite LEDs.
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