| 1. |
- Su, Yueling, et al.
(author)
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High-efficiency organic solar cells processed from a halogen-free solvent system
- 2023
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In: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 66:8, s. 2380-2388
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Journal article (peer-reviewed)abstract
- The use of non-halogenated solvents for the green manufacture of high-efficiency organic solar cells (OSCs) is important for their future application. However, the power conversion efficiency (PCE) of the non-halogenated solvent processed OSCs is generally lower than their halogenated counterpart due to the poor film microstructure caused by the solubility issue. Herein, we propose a halogen-free solvent system to optimize film microstructure of the photovoltaic blend based on the polymer donor D18 and small-molecule acceptor (SMA) L8-BO towards high-efficiency OSCs. The solvent system is consisted of a main solvent carbon disulfide and an additive paraxylene, where the former ensures the good solution-processability and promotes the solution aggregation of L8-BO, and the latter can finely control the phase-separation process by selectively dissolving the SMA. This solvent combination robustly produces a high-quality active layer, i.e., the bicontinuous networks of donor and acceptor with nano-sized phase-separation and strong & pi;-& pi; stacking. With the effective charge generation, transport and collection, the resulting device from the non-halogenated solvent system shows a high PCE of 17.50%, which is comparable to that of the device prepared from the halogenated solvent chloroform (ca. 17.11%). This article proposes a new strategy for the green fabrication of high-efficiency OSCs to accelerate their industrialization.
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| 2. |
- Wang, Shurong, et al.
(author)
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Comparison of the pyrolysis behavior of lignins from different tree species
- 2009
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In: Biotechnology Advances. - : Elsevier BV. - 0734-9750 .- 1873-1899. ; 27:5, s. 562-567
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Journal article (peer-reviewed)abstract
- Despite the increasing importance of biomass pyrolysis. little is known about the pyrolysis behavior of lignin-one of the main components of biomass-due to its structural complexity and the difficulty in its isolation. In the present study, we extracted lignins from Manchurian ash (Fraxinus mandschurica) and Mongolian Scots pine (Pinus sylvestris var. mongolica) using the Bjorkman procedure, which has little effect on the structure of lignin. Fourier transform infrared (FTIR) spectrometry was used to characterize the microstructure of the Bjorkman lignins, i.e., milled wood lignins (MWLs), from the different tree species. The pyrolysis characteristics of MWLs were investigated using a thermogravimetric analyzer, and the release of the main volatile and gaseous products of pyrolysis were detected by FTIR spectroscopy. During the pyrolysis process, MWLs underwent thermodegradation over a wide temperature range. Manchurian ash MWL showed a much higher thermal degradation rate than Mongolian Scots pine MWL in the temperature range from 290-430 degrees C. High residue yields were achieved at 37 wt.% for Mongolian Scots pine MWL and 26 wt.% for Manchurian ash MWL. In order to further investigate the mechanisms of lignin pyrolysis, we also analyzed the FTIR profiles for the main pyrolysis products (CO2, CO, methane, methanol, phenols and formaldehyde) and investigated the variation in pyrolysis products between the different MWLs.
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| 3. |
- Yun, Xiaobo, et al.
(author)
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Impacts of climate change and reservoir operation on streamflow and flood characteristics in the Lancang-Mekong River Basin
- 2020
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 590
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Journal article (peer-reviewed)abstract
- © 2020 Elsevier B.V. The Lancang-Mekong River Basin (LMRB) is one of the most important transboundary river basins in Asia. While climate change perturbs the streamflow and affects flood events, reservoir operation may mitigate or aggravate this impact. Therefore, quantitative assessment of the climate change impact and reservoir effect on the LMRB is a vital prerequisite for future hydropower development and environmental protection. This study aimed to estimate the variation of the streamflow and flood characteristics affected by climate change and reservoir operation within the LMRB. A reservoir module was incorporated into the Variable Infiltration Capacity (VIC) model to simulate the streamflow susceptible to the reservoirs. It was found that the reservoirs had a substantial influence on the streamflow during 2008–2016, when many reservoirs were constructed in the LMRB. The reservoirs across the Lancang River (the upper Mekong River located in China) reduced the annual average streamflow by 5% at Chiang Sean station (northern Thailand) in 2008–2016, whereas their influence became undetectable downstream of Vientiane station (northern Laos). The streamflow changes downstream of Mukdahan station at southern Laos (including the stations in Cambodia and southern Vietnam) were mainly attributed to the local reservoirs and climate change. Compared with the baseline period of 1985–2007, the upstream reservoir operation dramatically affected streamflow at the midstream stations with higher dry season streamflow (+15% to +37%), but lower wet season streamflow was less affected (−2% to −24%) in 2008–2016. Climate change increased the magnitude and frequency of the flood by up to 14% and 45%, respectively, whereas the reservoir operation reduced them by 16% and 36%, respectively. Our findings provide insights into the interaction between climate change and reservoir operation and their integrated effects on the streamflow, informing and supporting water management and hydropower development in the LMRB.
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| 4. |
- Kreibich, Heidi, et al.
(author)
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Panta Rhei benchmark dataset : Socio-hydrological data of paired events of floods and droughts
- 2023
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In: Earth System Science Data. - : Copernicus Publications. - 1866-3508 .- 1866-3516. ; 15:5, s. 2009-2023
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Journal article (peer-reviewed)abstract
- As the adverse impacts of hydrological extremes increase in many regions of the world, a better understanding of the drivers of changes in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is currently a lack of comprehensive, empirical data about the processes, interactions, and feedbacks in complex human-water systems leading to flood and drought impacts. Here we present a benchmark dataset containing socio-hydrological data of paired events, i.e. two floods or two droughts that occurred in the same area. The 45 paired events occurred in 42 different study areas and cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed and in the quantity of socio-hydrological data. The benchmark dataset comprises (1) detailed review-style reports about the events and key processes between the two events of a pair; (2) the key data table containing variables that assess the indicators which characterize management shortcomings, hazard, exposure, vulnerability, and impacts of all events; and (3) a table of the indicators of change that indicate the differences between the first and second event of a pair. The advantages of the dataset are that it enables comparative analyses across all the paired events based on the indicators of change and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. The dataset can be used by the scientific community for exploratory data analyses, e.g. focused on causal links between risk management; changes in hazard, exposure and vulnerability; and flood or drought impacts. The data can also be used for the development, calibration, and validation of socio-hydrological models. The dataset is available to the public through the GFZ Data Services (Kreibich et al., 2023, 10.5880/GFZ.4.4.2023.001).
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| 5. |
- Kreibich, Heidi, et al.
(author)
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The challenge of unprecedented floods and droughts in risk management
- 2022
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In: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 608:7921, s. 80-86
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Journal article (peer-reviewed)abstract
- Risk management has reduced vulnerability to floods and droughts globally, yet their impacts are still increasing. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change.
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