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result(s) for
"Zeng, Qian"
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Interplay between oceanic subduction and continental collision in building continental crust
2022
Generation of continental crust in collision zones reflect the interplay between oceanic subduction and continental collision. The Gangdese continental crust in southern Tibet developed during subduction of the Neo-Tethyan oceanic slab in the Mesozoic prior to reworking during the India-Asia collision in the Cenozoic. Here we show that continental arc magmatism started with fractional crystallization to form cumulates and associated medium-K calc-alkaline suites. This was followed by a period commencing at ~70 Ma dominated by remelting of pre-existing lower crust, producing more potassic compositions. The increased importance of remelting coincides with an acceleration in the convergence rate between India and Asia leading to higher basaltic flow into the Asian lithosphere, followed by convergence deceleration due to slab breakoff, enabling high heat flow and melting of the base of the arc. This two-stage process of accumulation and remelting leads to the chemical maturation of juvenile continental crust in collision zones, strengthening crustal stratification.
Gangdese arc magmatism, Tibet, was initially dominated by fractional crystallization of mantle derived magmas, followed by the remelting of these rocks during collision. These two stages lead to the stratification of the juvenile continental crust
Journal Article
Seismically imaged lithospheric delamination and its controls on the Mesozoic Magmatic Province in South China
2023
The current lithospheric root of the South China Block has been partly removed, yet what mechanisms modified the lithospheric structure remain highly controversial. Here we use a new joint seismic inversion algorithm to image tabular high-velocity anomalies at depths of ~90–150 km in the asthenosphere beneath the convergent belt between the Yangtze and Cathaysia blocks that remain weakly connected with the stable Yangtze lithosphere. Based on obtained seismic images and available geochemical data, we interpret these detached fast anomalies as partially destabilized lower lithosphere that initially delaminated at 180–170 Ma and has relaminated to their original position after warming up in the mantle by now. We conclude that delamination is the most plausible mechanism for the lithospheric modification and the formation of a Mesozoic Basin and Range-style magmatic province in South China by triggering adiabatic upwelling of the asthenosphere and consequent lithospheric extension and extensive melting of the overlying crust.
Lithospheric delamination is seismically imaged in the asthenosphere and is responsible for the lithospheric modification and the formation of a Mesozoic Basin and Range-style magmatic province in South China by joint analysis of geochemical data.
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Journal Article
K‐Rich Adakite‐Like Rocks in Central Tibet: Fractional Crystallization of a Hydrous, Alkaline Primitive Melt
2023
K‐rich adakite‐like rocks (KARs) in post‐collisional settings, such as in Tibet, have been widely linked with the melting of pre‐existing thickened crust. Here, we investigate geochemical data of the Late Eocene (38–34 Ma) volcanic rocks including KARs from the southern Qiangtang terrane (SQT) of central Tibet. The data reveal that: (a) the volcanic rocks define a fractionation trend from high‐K alkaline basalt to high‐K calc‐alkaline rhyolite, with a continuous compositional range and (b) they are characterized by a narrow range of depleted Sr–Nd isotopic compositions relative to the pre‐Eocene SQT crust. We contend that the KARs in the SQT resulted from fractional crystallization of hydrous, alkaline melts derived from the lithospheric mantle where fractionation was dominated by amphibole and plagioclase. Partial melting of the lithospheric mantle beneath the SQT was possibly triggered by thermal perturbations owing to the north‐directed subduction of the Indian continental lithosphere beneath southern Tibet. Plain Language Summary Adakites were originally defined as silica‐rich magmas produced by melting of basalts in subducting oceanic crust. They are Na‐rich with low K2O and K2O/Na2O, and are characterized by high Sr/Y and La/Yb and low Y and Yb. In post‐collisional settings, such as in Tibet, silica‐rich magmatic rocks with high Sr/Y and La/Yb have been identified, but they are not sodic as true adakites, and are rich in K2O, forming K‐rich adakite‐like rocks (KARs). They have been linked with the melting of pre‐existing crustal rocks at high pressures where garnet is present. We investigate geochemical data of the Late Eocene (38–34 Ma) volcanic rocks that include KARs from the southern Qiangtang terrane (SQT) of central Tibet. We conclude that these KARs were not products of crustal melting at high pressures, but resulted from extreme fractional crystallization of lithospheric mantle‐derived, hydrous, primitive alkaline melts. Given that extreme fractional crystallization commonly occurs in a compressive regime, we argue that the lithospheric mantle underneath the SQT underwent melting during a compressive regime possibly due to thermal perturbations, driven by north‐directed subduction of the Indian continental lithosphere beneath southern Tibet. Key Points Late Eocene K‐rich adakite‐like rocks (KARs) in the S. Qiangtang terrane resulted from fractional crystallization of a primitive alkaline melt Fractionation was dominated by amphibole and plagioclase KARs from the S. Qiantang terrane have a different origin from those of the Lhasa terrane
Journal Article
Atomistic Insights into the Effect of Functional Groups on the Adsorption of Water by Activated Carbon for Heat Energy Storage
by
Zhu, Chuan-Yong
,
Gong, Liang
,
Duan, Xin-Yue
in
Activated carbon
,
Adsorption
,
adsorption heat storage
2023
Adsorption heat storage holds great promise for solar energy applications. The development of new adsorbent materials is currently the research focus in this area. The present work designs several activated carbon models with different functional groups, including -OH, -NH2, -COOH, and -SO3H, and explores the influence of functional groups’ categories and numbers on the water adsorption capacity of the activated carbon using the GCMC method. The adsorption mechanism between functional groups and water molecules is analyzed using density functional theory. The results show that the functional groups could significantly improve the water adsorption capacity of activated carbon due to the hydrogen bond between functional groups and water molecules. In the scope of this paper, under low pressure, the activated carbon with -SO3H exhibits the best adsorption capacity, followed by the activated carbon with -COOH. Under low and medium pressure, increasing the number of -SO3H functional groups could increase the water adsorption capacity; however, when the pressure is high, increasing the functional group numbers might decrease the water adsorption capacity. As the temperature increases, the water adsorption capacity of activated carbons decreases, and the activated carbon with -SO3H is proven to have excellent application prospects in heat energy storage.
Journal Article
Changes in muscle ultrasound for the diagnosis of intensive care unit acquired weakness in critically ill patients
2021
To test diagnostic accuracy of changes in thickness (TH) and cross-sectional area (CSA) of muscle ultrasound for diagnosis of intensive care unit acquired weakness (ICU-AW). Fully conscious patients were subjected to muscle ultrasonography including measuring the changes in TH and CSA of biceps brachii (BB) muscle, vastus intermedius (VI) muscle, and rectus femoris (RF) muscles over time. 37 patients underwent muscle ultrasonography on admission day, day 4, day 7, and day 10 after ICU admission, Among them, 24 were found to have ICW-AW. Changes in muscle TH and CSA of RF muscle on the right side showed remarkably higher ROC-AUC and the range was from 0.734 to 0.888. Changes in the TH of VI muscle had fair ROC-AUC values which were 0.785 on the left side and 0.779 on the right side on the 10th day after ICU admission. Additionally, Sequential Organ Failure Assessment (SOFA), Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores also showed good discriminative power on the day of admission (ROC-AUC 0.886 and 0.767, respectively). Ultrasonography of changes in muscles, especially in the TH of VI muscle on both sides and CSA of RF muscle on the right side, presented good diagnostic accuracy. However, SOFA and APACHE II scores are better options for early ICU-AW prediction due to their simplicity and time efficiency.
Journal Article
Device-Driven Service Allocation in Mobile Edge Computing with Location Prediction
2025
With the rapid deployment of edge base stations and the widespread application of 5G technology, Mobile Edge Computing (MEC)has gradually transitioned from a theoretical concept to practical implementation, playing a key role in emerging human-machine interactions and innovative mobile applications. In the MEC environment, efficiently allocating services, effectively utilizing edge device resources, and ensuring timely service responses have become critical research topics. Existing studies often treat MEC service allocation as an offline strategy, where the real-time location of users is used as input, and static optimization is applied. However, this approach overlooks dynamic factors such as user mobility. To address this limitation, this paper constructs a model based on constraints, optimization objectives, and server connection methods, determines experimental parameters and evaluation metrics, and sets up an experimental framework. We propose an Edge Location Prediction Model (ELPM) suitable for the MEC scenario, which integrates Spatial-Temporal Graph Neural Networks and attention mechanisms. By leveraging attention parameters, ELPM acquires spatio-temporal adaptive weights, enabling accurate location predictions. We also design an improved service allocation strategy, MESDA, based on the Gray Wolf Optimization (GWO) algorithm. MESDA dynamically adjusts its exploration and exploitation components, and introduces a random factor to enhance the algorithm’s ability to determine the direction during later stages. To validate the effectiveness of the proposed methods, we conduct multiple controlled experiments focusing on both location prediction models and service allocation algorithms. The results show that, compared to the baseline methods, our approach achieves improvements of 2.56%, 5.29%, and 2.16% in terms of the average user connection to edge servers, average service deployment cost, and average service allocation execution time, respectively, demonstrating the superiority and feasibility of the proposed methods.
Journal Article
Amphibole-rich cumulate xenoliths in the Zhazhalong intrusive suite, Gangdese arc: Implications for the role of amphibole fractionation during magma evolution
by
Hou, Zeng-Qian
,
Wang, Qiang
,
Zhou, Jin-Sheng
in
Amphibole
,
Amphiboles
,
Chemical fingerprinting
2020
Amphibole fractionation during the early evolution of arc magmas has been widely inferred on the basis of distinctive geochemical fingerprints of the evolved melts, although amphibole is rarely found as a major mineral phase in arc volcanic rocks, so-called cryptic amphibole fractionation. Here, we present a detailed case study of xenoliths of amphibole-rich cumulate from the Zhazhalong intrusive suite, Gangdese arc, which enables an investigation of this differentiation process using a combination of petrological observations and in situ geochemical constraints. Evidence that the xenoliths represent fragments of igneous cumulates includes: (1) the presence of an amphibole-dominated crystal framework; (2) mineral and whole-rock Fe–Mg exchange coefficients; (3) rare-earth element patterns that are similar in the amphiboles and the xenoliths; (4) the compositions of basaltic to andesitic liquids in equilibrium with amphiboles; and (5) enrichment of the xenoliths in compatible elements and depletion in incompatible elements. The amount of trapped liquid based on La, Ce, and Dy abundances varies from ~12 to ~20%. Actinolitic cores within amphibole grains likely represent reaction between olivine precursor and hydrous melt, as evidenced by their high Cr and Ni contents. Amphibole thermometry and oxybarometry calculations indicate that crystal accumulation occurred over temperatures of 857–1014 °C, at mid-crustal pressures of 312 to 692 MPa and oxygen fugacity between 0.4 and 1.9 log units above the nickel–nickel oxide buffer. Quantification of the major-element compositions of the parent liquids indicates that the Zhazhalong amphibole cumulates crystallized from basaltic to andesitic magmas, probably with a shoshonitic affinity, and with SiO
contents of 46.4–66.4 wt%. Appropriate partition coefficients, calculated using a parameterized lattice strain model and an empirical partitioning scheme, were employed to calculate the trace-element compositions of the liquids in equilibrium with amphibole. Our results confirm that Dy/Yb and Dy/Dy* ratios, which decrease with increasing degrees of differentiation, can be used as robust signatures of amphibole fractionation. This work presents a direct snapshot of the process of amphibole fractionation and provides a natural example of the hidden amphibole “sponge” in arc crust. In particular, this study also suggests that some appinites likely represent amphibole-rich cumulates, which may help to explain the genesis of other unusual but petrologically significant rocks.
Journal Article
Repurposing cancer drugs identifies kenpaullone which ameliorates pathologic pain in preclinical models via normalization of inhibitory neurotransmission
2021
Inhibitory GABA-ergic neurotransmission is fundamental for the adult vertebrate central nervous system and requires low chloride concentration in neurons, maintained by KCC2, a neuroprotective ion transporter that extrudes intracellular neuronal chloride. To identify
Kcc2
gene expression‑enhancing compounds, we screened 1057 cell growth-regulating compounds in cultured primary cortical neurons. We identified kenpaullone (KP), which enhanced
Kcc2/KCC2
expression and function in cultured rodent and human neurons by inhibiting GSK3ß. KP effectively reduced pathologic pain-like behavior in mouse models of nerve injury and bone cancer. In a nerve-injury pain model, KP restored
Kcc2
expression and GABA-evoked chloride reversal potential in the spinal cord dorsal horn. Delta-catenin, a phosphorylation-target of GSK3ß in neurons, activated the
Kcc2
promoter via KAISO transcription factor. Transient spinal over-expression of delta-catenin mimicked KP analgesia. Our findings of a newly repurposed compound and a novel, genetically-encoded mechanism that each enhance
Kcc2
gene expression enable us to re-normalize disrupted inhibitory neurotransmission through genetic re-programming.
Lack of expression and function of chloride ion-extruding transporter KCC2 in central neurons, a consequence of various forms of neural injury, is strongly suggested to contribute to chronic pain. Here the authors identify from a screen of cancer drugs a kinase-inhibitor, kenpaullone, as an enhancer of
Kcc2/KCC2
gene expression and show that it (i) alleviates pain like behaviour in animal models, (ii) repairs neural-circuit disrupting elevated chloride in pain relay neurons in the dorsal spinal cord.
Journal Article
AdS/BCFT and Island for curvature-squared gravity
by
Miao, Rong-Xin
,
Hu, Qi-Lin
,
Zeng, Yu-Qian
in
AdS-CFT Correspondence
,
Boundary conditions
,
Branes
2022
A
bstract
In this paper, we investigate AdS/BCFT for curvature-squared gravity. To warm up, we start with Gauss-Bonnet gravity. We derive the one point function of stress tensor and show that the central charge related to the norm of displacement operator is positive for the couplings obeying causality constraints. Furthermore, by imposing the null energy condition on the end-of-the-world brane, we prove the holographic g-theorem for Gauss-Bonnet gravity. This corrects a wrong point of view in the literature, which claims that the holographic g-theorem is violated for Gauss-Bonnet gravity. As a by-product, we obtain the boundary entropy and A-type boundary central charges in general dimensions. We also study AdS/BCFT for general curvature-squared gravity. We find that it is too restrictive for the shape of the brane and the dual BCFT is trivial if one imposes Neumann boundary conditions for all of the gravitational modes. Instead, we propose to impose Dirichlet boundary condition for the massive graviton, while imposing Neumann boundary condition for the massless graviton. In this way, we obtain non-trivial shape dependence of stress tensor and well-defined central charges. In particular, the holographic g-theorem is satisfied by general curvature-squared gravity. Finally, we discuss the island and show that the Page curve can be recovered for Gauss-Bonnet gravity. Interestingly, there are zeroth-order phase transitions for the Page curve within one range of couplings obeying causality constraints. Generalizing the discussions to holographic entanglement entropy and holographic complexity in AdS/CFT, we get new constraints for the Gauss-Bonnet coupling, which is stronger than the causality constraint.
Journal Article