Reservoir delineation and cumulative impacts assessment in large river basins: A case study of the Yangtze River Basin

Ph.DDOCTOR OF PHILOSOPH

Multispectroscopic and Computational Study of the Interaction between α-Cembrenediol and Bovine Serum Albumin

α-Cembrenediol displays a diverse array of biological activities, encompassing antibacterial, antitumor, and neuroprotective effects. To comprehensively understand the in vivo transport, distribution, and elimination mechanisms associated with α-cembrenediol, its interaction with bovine serum albumin (BSA) was investigated. In this study, the interaction between α-cembrenediol and BSA was explored using various techniques, including UV absorption, steady-state fluorescence, circular dichroism spectrum, molecular docking, and molecular dynamics simulation. The results showed that there was a clear interaction between BSA and α-cembrenediol. Specifically, the KSV and Kb decreased with increasing temperature at 293, 303, and 310 K, indicating that α-cembrenediol interacted with BSA through a static quenching mechanism. Furthermore, the number of binding sites was approximately 1 at the three temperatures, suggesting the presence of a single specific binding site for α-cembrenediol on BSA. Moreover, the binding process occurred spontaneously (ΔG<0), primarily driven by hydrogen bonds and van der Waals forces (ΔH<0 and ΔS<0). α-Cembrenediol bound to the Sudlow site I of BSA. Binding of BSA to α-cembrenediol also caused its conformation to change. This study provides essential insights into the interaction between α-cembrenediol and BSA, contributing to a better understanding of the pharmacokinetic properties of the compound

Extensive and drastically different alpine lake changes on Asia's high plateaus during the past four decades

Asia's high plateaus are sensitive to climate change and have been experiencing rapid warming over the past few decades. We found 99 new lakes and extensive lake expansion on the Tibetan Plateau during the last four decades, 1970–2013, due to increased precipitation and cryospheric contributions to its water balance. This contrasts with disappearing lakes and drastic shrinkage of lake areas on the adjacent Mongolian Plateau: 208 lakes disappeared, and 75% of the remaining lakes have shrunk. We detected a statistically significant coincidental timing of lake area changes in both plateaus, associated with the climate regime shift that occurred during 1997/1998. This distinct change in 1997/1998 is thought to be driven by large-scale atmospheric circulation changes in response to climate warming. Our findings reveal that these two adjacent plateaus have been changing in opposite directions in response to climate change. These findings shed light on the complex role of the regional climate and water cycles and provide useful information for ecological and water resource planning in these fragile landscapes.Publisher PDFPeer reviewe

Interactions between all pairs of neighboring trees in 16 forests worldwide reveal details of unique ecological processes in each forest, and provide windows into their evolutionary histories

When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands’ physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees’ distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions

Spatiotemporal trends in flood hazards using MODIS time-series images in the Pearl River Basin (China)

The Pearl River Basin (PRB), as one of the most prosperous and densely populated areas in China, is a flood-prone area in which huge casualties and big economic losses constantly happen. Therefore, it is of great importance for the study on the characteristics of flood hazards and spatiotemporal trends in the PRB. Based on Google Earth Engine, this study combined 913-phase Modis 8-Day composite (MOD09Q1.006) images with 30-meters SRTM DEM to monitor flood dynamics in the PRB from 2000 to 2019 using an integrated threshold method. The approach synthesized several key factors, including spectrum characters of water body, cloud and the slope (slope<1\uba) information derived from SRTM DEM. Moreover, Sentinel-1 images were used to validate the accuracy of flood inundation maps. The results indicated that, from 2000 to 2019, the flood inundation area in PRB expanded significantly, especially in the Pearl River Delta region. With the development of urbanization, the expansion of impervious surfaces would probably increase the probability of flood hazard

Delineation of China's reservoirs and lakes using remote sensing techniques

We used remote sensing images to provide the first complete picture of the reservoirs and lakes located within China. We extracted 89 691 reservoirs, covering about 26 755 km2 of the land surface. By applying an empirical formula relating reservoir storage capacity and surface area, we estimated the total storage capacity to be about 770 km3. Also, we delineated more than 180 000 lakes and ponds, with a total surface area of about 79 767 km2. These include 2721 lakes larger than 1 km2. Through comparison with previous studies, we found that dramatic changes have occurred over the past decades. Reservoir construction and water diversion have changed the spatial distribution and seasonal variation of water resources and have made the river systems fragmented. Additionally, this study found that more than 200 lakes of >1 km2 on the Mongolia-Xinjiang Plateau and the Eastern Plain have disappeared, but about 50 lakes >1 km2 have appeared on the Tibetan Plateau. The disappearing lakes on the Mongolia-Xinjiang Plateau and the newly appearing lakes on the Tibetan Plateau could be a result of climate change; whereas the disappearance of lakes on the Eastern Plain, especially in the middle-lower reaches of the Yangtze and Huaihe River basin, reflect the impact of human activities, such as land reclamation and urbanization. The database of delineated reservoirs will be employed to estimate the total amount of sediment trapped behind dams. Copyright © 2012 IAHS Press.Link_to_subscribed_fulltex

ANALYSIS OF RIVETING CARRYING CAPACITY FOR COMPOSITE TAIL SHAFT OF HELICOPTER TRANSMISSION SYSTEM

The composite material has the advantages of high specific strength and high specific stiffness, which could reduce the structural weight effectively when it was applied to the tail shaft of helicopter transmission system. The connection with the composite tail shaft and flange usually adopt riveting, the riveted area was the weakness of the tail shaft. In this paper, the riveting analysis model of composite tail shaft and flange was established by ANSYS ACP software. The Tsai-Wu failure criterion was adopted for the failure of the riveted joints. The riveting structure lost its function of carrying capacity when the failure zone of the riveting was more than the coverage area of gasket. By comparing with the results of static torsion test, the calculated results were in good agreement with the experimental results