| 1. |
- Tan, Liangcheng, et al.
(författare)
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Rainfall variations in central Indo-Pacific over the past 2,700 y
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:35, s. 17201-17206
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Tidskriftsartikel (refereegranskat)abstract
- Tropical rainfall variability is closely linked to meridional shifts of the Intertropical Convergence Zone ( ITCZ) and zonal movements of the Walker circulation. The characteristics and mechanisms of tropical rainfall variations on centennial to decadal scales are, however, still unclear. Here, we reconstruct a replicated stalagmite-based 2,700-y-long, continuous record of rainfall for the deeply convective northern central Indo-Pacific ( NCIP) region. Our record reveals decreasing rainfall in the NCIP over the past 2,700 y, similar to other records from the northern tropics. Notable centennial-to decadal-scale dry climate episodes occurred in both the NCIP and the southern central Indo-Pacific ( SCIP) during the 20th century [ Current Warm Period ( CWP)] and the Medieval Warm Period ( MWP), resembling enhanced El Nino-like conditions. Further, we developed a 2,000-y-long ITCZ shift index record that supports an overall southward ITCZ shift in the central Indo-Pacific and indicates southward mean ITCZ positions during the early MWP and the CWP. As a result, the drying trend since the 20th century in the northern tropics is similar to that observed during the past warm period, suggesting that a possible anthropogenic forcing of rainfall remains indistinguishable from natural variability.
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| 2. |
- Jiang, Guancong, et al.
(författare)
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Critical Role of Carbonized Cellulose in the Evolution of Highly Porous Biocarbon : Seeing the Structural and Compositional Changes of Spent Mushroom Substrate by Deconvoluted Thermogravimetric Analysis
- 2020
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 59:52, s. 22541-22548
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Tidskriftsartikel (refereegranskat)abstract
- Structural optimization of activated carbon (AC) mainly relies on experience, which depends on the intrinsic structure of biochar, processing conditions, and the interplay of both parties. A fundamental understanding of the pore structure evolution related to the intrinsic structure and composition remains a challenge. In this work, spent mushroom substrate, a rapidly growing byproduct of the mushroom cultivation industry, is used as model biomass to prepare AC under CO2 activation. The structure and composition of the AC products with different activation durations were systematically analyzed with several characterization techniques including N2 adsorption–desorption, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. A multipeak separation method is developed that enables quantitative analysis of carbonized lignin and carbonized cellulose. A peak area ratio parameter is proposed to describe the retention of cellulose. It is revealed that higher retention of carbonized cellulose corresponds to a larger Brunauer–Emmett–Teller (BET) surface area, demonstrating the dominant role of cellulose in the pore structure development process. This work not only provides a qualitative correlation between cellulose and rich porous structure but also offers a new quantitative tool to understand the structure–composition relationship during the pore evolution process.
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