| 1. |
- Liu, Xiaoxuan, et al.
(författare)
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Identifying patterns and hotspots of global land cover transitions using the ESA CCI Land Cover dataset
- 2018
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Ingår i: Remote Sensing Letters. - : Taylor & Francis Group. - 2150-704X .- 2150-7058. ; 9:10, s. 972-981
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Tidskriftsartikel (refereegranskat)abstract
- Land use/land cover change is a continuing research focus, not only because of its ecological and environmental effects but also because of the difficulties with accurate change detection and analysis uncertainty. The principal difficulty is the lack of a long time series of annual global land cover maps at a fine resolution. A new global long-term time series of annual datasets called the European Space Agency (ESA) Climate Change Initiative Land Cover (CCI-LC) has been published, making it possible to detect the global land cover changes. Using this ESA CCI-LC product from 1992-2015, we quantified the annual transitions of land cover change globally with the trajectory analysis method, analyzed the changes patterns and identified the land cover change hotspots. The total land cover change area for the world was 5.99 million km(2), amounting to only 3.36% of the total continental area. Most changes happened in forest and cropland, accounting 32% of all the land cover changes. Most land cover changes happened in tropical ecoregions. Grassland changes were mainly distributed in the temperate ecoregions, while cropland expansion occurred mainly in the tropical or subtropical ecoregions. The hotspots identified in this paper could provide target areas for further research.
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| 2. |
- Yu, ChaoQing, et al.
(författare)
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Managing nitrogen to restore water quality in China
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 567:7749, s. 516-520
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Tidskriftsartikel (refereegranskat)abstract
- The nitrogen cycle has been radically changed by human activities(1). China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers(2,3) and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary'(4) in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 +/- 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 +/- 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 +/- 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 +/- 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.
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| 3. |
- Du, Zhixue, et al.
(författare)
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In Situ Monitoring of p53 Protein and MDM2 Protein Interaction in Single Living Cells Using Single-Molecule Fluorescence Spectroscopy
- 2018
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:10, s. 6144-6151
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Tidskriftsartikel (refereegranskat)abstract
- Protein-protein interactions play a central role in signal transduction, transcription regulations, enzymatic activity, and protein synthesis. The p53 protein is a key transcription factor, and its activity is precisely regulated by the p53-MDM2 interaction. Although the p53-MDM2 interaction has been studied, it is still not clear how p53 structures and external factors influence the p53-MDM2 interaction in living cells. Here, we developed a direct method for monitoring the p53-MDM2 interaction in single living cells using single-molecule fluorescence cross-correlation spectroscopy with a microfluidic chip. First, we labeled p53 and MDM2 proteins with enhanced green fluorescent protein (EGFP) and mCherry, respectively, using lentivirus infection. We then designed various mutants covering the three main domains of p53 (tetramerization, transactivation, and DNA binding domains) and systematically studied effects of p53 protein primary, secondary, and quaternary structures on p53 MDM2 binding affinity in single living cells. We found that p53 dimers and tetramers can bind to MDM2, that the binding affinity of p53 tetramers is higher than that of p53 dimers, and that the affinity is closely correlated to the helicity of the p53 transactivation domain. The hot-spot mutation R175H in the DNA-binding domain reduced the binding of p53 to MDM2. Finally, we studied effects of inhibitors on p53-MDM2 interactions and dissociation dynamics of pS3-MDM2 complexes in single living cells. We found that inhibitors Nutlin 3 alpha and MI773 efficiently inhibited the pS3-MDM2 interaction, but RITA did not work in living cells. This study provides a direct way for quantifying the relationship between protein structure and protein protein interactions and evaluation of inhibitors in living cells.
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| 4. |
- Zhang, Chi, et al.
(författare)
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Economic Assessment of Photovoltaic Water Pumping Integration with Dairy Milk Production
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- As dairy consumption grows, domestic dairy farms face challenges in reducing the cost of feeds and the production of high-quality milk for market demands. This paper aims to introduce and integrate solar energy into the milk production chain to investigate its economic performance. By collecting data on milk production processes from 11 dairy farms in China, we quantified electricity usage and costs of milk production to identify the best and worst cases. Crop yields response to the water demand and the electricity requirements of the dairy farms were considered. The study simulated scenarios of self-sufficiency at 20%, 80%, and 100%, in the identified farms by integrating a photovoltaic water pumping (PVWP) system to provide both power and water for alfalfa and other feeds’ irrigation and subsequent milk production. We evaluated annual discounted cost, revenue and net profit under each scenario and case. The results showed that a dairy farm with an integrated PVWP system and self-sufficient feeds would lead to value add-ins, such as electricity saving with solar energy generation, economic cost saving of crops, and CO2 emission reduction. The analysis on return on investment (ROI) and internal rate of return (IRR) revealed that not all the self-sufficient feeds can bring positive marginal profit. Among the investigated scenarios and cases, the dairy farm marked out by the highest ROI with 3.12 and IRR with 20.4%, was the farm where the integrated PVWP system was used to reach 20% self-sufficiency (self-production of only alfalfa). The other scenarios and cases with higher levels of self-sufficiency showed lower ROIs and IRRs. This indicates that high self-production levels of feeds decrease the total profit due to high investment cost. Sensitivity analyses of crop price and operational cost were conducted for ROI with single and double factor approaches. Scale and production of feeds proportions should be carefully considered in improving the economic performance of dairy milk production.
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| 5. |
- Zhang, Chi, et al.
(författare)
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Economic assessment of photovoltaic water pumping integration with dairy milk production
- 2018
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Ingår i: Energy Conversion and Management. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0196-8904 .- 1879-2227. ; 177, s. 750-764
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Tidskriftsartikel (refereegranskat)abstract
- As dairy consumption grows, domestic dairy farms face challenges in reducing the cost of feeds and the production of high-quality milk for market demands. This paper aims to introduce and integrate solar energy into the milk production chain to investigate its economic performance. By collecting data on milk production processes from 11 dairy farms in China, we quantified electricity usage and costs of milk production to identify the best and worst cases. Crop yields response to the water demand and the electricity requirements of the dairy farms were considered. The study simulated scenarios of self-sufficiency at 20%, 80%, and 100%, in the identified farms by integrating a photovoltaic water pumping (PVWP) system to provide both power and water for alfalfa and other feeds' irrigation and subsequent milk production. We evaluated annual discounted cost, revenue and net profit under each scenario and case. The results showed that a dairy farm with an integrated PVWP system and self-sufficient feeds would lead to value add-ins, such as electricity saving with solar energy generation, economic cost saving of crops, and CO2 emission reduction. The analysis on return on investment (ROI) and internal rate of return (IRR) revealed that not all the self-sufficient feeds can bring positive marginal profit. Among the investigated scenarios and cases, the dairy farm marked out by the highest ROI with 3.12 and IRR with 20.4%, was the farm where the integrated PVWP system was used to reach 20% self-sufficiency (self-production of only alfalfa). The other scenarios and cases with higher levels of self-sufficiency showed lower ROIs and IRRs. This indicates that high self-production levels of feeds decrease the total profit due to high investment cost. Sensitivity analyses of crop price and operational cost were conducted for ROI with single and double factor approaches. Scale and production of feeds proportions should be carefully considered in improving the economic performance of dairy milk production.
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