| 1. |
- Lin, Fangyuan, 1996-, et al.
(författare)
-
Seasonal to decadal variations of precipitation oxygen isotopes in northern China linked to the moisture source
- 2024
-
Ingår i: npj Climate and Atmospheric Science. - 2397-3722. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- A precise characterization of moisture source and transport dynamics over the inland margins of monsoonal China is crucial for understanding the climatic significance of precipitation oxygen isotope (δ18Op) variability preserved in the regional proxy archives. Here, we use a general circulation model with an embedded water-tagging module to quantify the role of moisture dynamics on the seasonal to decadal variations of δ18Op in northern China. Our data indicate that during the non-monsoon season, the δ18Op variability is dominated by the temperature effect. Conversely, in the summer monsoon season, the moisture contributions from the low-latitude land areas (LLA), the Pacific Ocean (PO), and the North Indian Ocean (NIO) override the temperature effect and influence the summer δ18Op. Intensified upstream convection along the NIO moisture transport pathway results in a more negative summer δ18Op compared to moisture transported from the PO and LLA regions. Our analysis shows a decadal shift in summer δ18Op around the mid-1980s, marking changes in the relative contribution of oceanic moisture from PO and NIO in response to changes in the atmospheric circulation patterns influenced by the Pacific Decadal Oscillation. We suggest that such decadal-scale δ18Op variability can be recorded in the natural archives from the region, which can provide valuable insights into understanding past climate variability.
|
|
| 2. |
- Fang, Mei, et al.
(författare)
-
'In-situ' ink-jet printed Fe-doped MgO thin films with tunable ferromagnetism
- 2020
-
Ingår i: Zhongguó wùli xuékan. - : Elsevier. - 0577-9073. ; 67, s. 398-404
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetism in wide band gap materials is of great interests for future spintronic device applications. We prepared MgO and Fe-doped MgO films 'in-situ' on substrates by inkjet printing, and investigated the ferromagnetism tuned by the doping of Fe, the annealing temperature and the film thickness. It is found that the Fe-doping improves the crystallinity of the films with lattice structure changed by annealing temperature. The saturation magnetization (M-s) of the films enhanced by similar to 5 times comparing with the pure MgO thin film of similar thickness (similar to 90 nm), because of both the long-range ordering of localized 3d electrons in Fe and the defects induced magnetism. The M-s at 5 K decreases with the film thickness, which is mainly attributed to the interface induced ferromagnetism. The Fe-doped MgO films with ferromagnetism in this work can be used in future spintronic devices.
|
|
| 3. |
- Gao, Guangbin, et al.
(författare)
-
Understanding filamentous cyanobacteria and their adaptive niches in Lake Honghu, a shallow eutrophic lake
- 2025
-
Ingår i: Journal of Environmental Sciences (China). - 1001-0742. ; 152, s. 219-234
-
Tidskriftsartikel (refereegranskat)abstract
- Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms. However, underlying factors influencing the succession or coexistence of cyanobacteria, especially filamentous ones, remain poorly understood. Lake Honghu, a Ramsar Wetland of International Importance with degrading aquatic ecological quality, served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics. Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria, marked by high spatiotemporal variability in community structure. This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions. Species-specific density variations were linked to diverse environmental factors, with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations. The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter, whereas Dolichospermum and Cylindrospermopsis, which prefer higher temperatures, thrived in summer and autumn. Additionally, non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation. This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range. Current findings enhance our comprehension of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.
|
|
| 4. |
- Li, Jie, et al.
(författare)
-
Maximum number of subtrees in cacti and block graphs
- 2022
-
Ingår i: Aequationes Mathematicae. - : Springer. - 0001-9054 .- 1420-8903. ; 96, s. 1027-1040
-
Tidskriftsartikel (refereegranskat)abstract
- For a graph G, we denote by N(G) the number of non-empty subtrees of G. As a topological index based on counting, N(G) has some correlations to other well studied topological indices, including the Wiener index W(G). In this paper we characterize the extremal graphs with the maximum number of subtrees among all cacti of order n with k cycles. Similarly, the extremal graphs with the maximum number of subtrees among all block graphs of order n with k blocks are also determined and shown to have the minimum Wiener index within the same collection of graphs. Analogous results are also obtained for the number of connected subgraphs C(G). Finally, a general question is posed concerning the relation between the number of subtrees and the Wiener index of graphs.
|
|
