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Temperature dependence photoluminescence properties of ZnSe-based core-shell quantum dots

Optics Express 2025年第11期33卷 22588-22597页

作者： Zhang, Tingting Ma, Qing Li, Qingping Huang, Lanting Feng, Yuqiong Duan, Hongwei Chen, Xinlei Li, Qinghua Jin, Xiao Bai, Jinke Xu, Bing Key Laboratory of Environmentally Friendly Functional Materials and Devices School of Physics Science and Technology Lingnan Normal University Guangdong Zhanjiang524048 China School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Department of Materials and Chemical Engineering Taiyuan University Taiyuan030032 China

Heavy metal-free ZnSe-based core-shell quantum dots (QDs) are promising emitting material for achieving violet-blue luminescence. Investigating the temperature-dependent variations in the photoluminescence (PL) properties of ZnSe-based QDs will enhance our understanding of the intrinsic factors that influence their diverse luminescence characteristics. Here we select the optimally synthesized ZnSe core QDs with three diameters (4.1, 5.2, and 8.3 nm) and ZnSe/ZnS core-shell QDs to study their temperature-dependent photoluminescence properties. As the sample temperature is increased, the PL intensity decreases, the emission energy redshifts, and the spectral become broader. We observe a reduction in the exciton-longitudinal optical (LO)-phonon coupling constant from 21.7 meV to 16.1 meV as the diameter of ZnSe core QDs increased from 4.1 nm to 8.3 nm. This decrease is associated with a narrower homogeneous broadening of the emission spectrum. Besides, the epitaxial growth of a ZnS wide bandgap shells onto the ZnSe core QDs can effectively isolate the photogenerated excitons away from the inorganic-organic interface, thus reducing the PL peak width and increasing the exciton binding energy of the QDs. Our research provides a valuable addition to the existing studies on the photoluminescence properties of ZnSe-based core-shell QDs. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Atomic emission spectroscopy

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Integrated Co2 Capture and Conversion by Three-Step Chemical Looping Dry Reforming of Methane

SSRN

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SSRN 2025年

作者： Liu, Yunlian Liu, Mingkai Shen, Yuanhui Li, Yang Gai, Zhongrui Zhang, Ruqi Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The integrated CO2 capture and conversion (ICCC) has emerged as a promising and cost-effective pathway for achieving carbon neutrality. However, limited energy-efficient pathways and durable materials for ICCC systems remains challenging. This study proposes a novel approach that synergistically integrates CO2 capture and conversion through a unified chemical framework. The method employs Li-based sorbents for CO2 capture, coupled with CH4-driven sorbent regeneration that is seamlessly integrated with chemical looping dry reforming of methane (CLDRM), enabling in-situ CO2 conversion. By coupling sorbent regeneration with CLDRM, this system enhances decarbonation kinetics through Le Chatelier's principle via continuous CO2 conversion. One-step calcination synthesized Li-based sorbents particles exhibit stable CO2 capture capacity of 5.25 mmol·g-1 within 15 min per cycle, maintaining 7.5-15% operational efficiency over 40 cycles at 600 ℃. In CLDRM, hydrogen radicals from CH4 dissociation promote the conversion of CO2 to intermediates, lowering the apparent activation energy of sorbents regeneration by 29.2%. Through systematic optimization in a fixed-bed reactor, we achieved 90% CO2 uptake and 85% CH4 conversion, with syngas production rates reaching 13.71 mL·min-1·g-1. Notably, the H2/CO molar ratio in syngas stabilizes ~1.6, aligns with iron-based Fischer-Tropsch and methanol synthesis to produce valuable fuels. This integrated system maintains >80% syngas purity with © 2025, The Authors. All rights reserved.

关键词： Activation energy

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A study on free radical behaviors and reactions in supercritical water using quantum chemical simulation

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Journal of Molecular Liquids 2025年 419卷

作者： Ding, Weijing Takahashi, Osamu Wang, Junying Jin, Hui School of Transportation and Vehicle Engineering Shandong University of Technology Shandong Zi'bo255000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan

Supercritical water (SCW) gasification is one of clean and efficient utilization way of biomass, other organic matters or coal for hydrogen production, in which radical reactions studies in SCW are limited but crucial. Density-functional tight-binding (DFTB) molecular simulation is one of efficient and convenient approaches to investigate these microscopic processes. Therefore, free radical reactions in severe SCW environment were investigated via DFTB calculations in this work. The results showed that the order of the free radicals containing bond cleavages reacted in SCW environment was ·OH, ·CH, ·CH2, ·HO2, ·CH3 and ·C6H5 under the same conditions. The reaction processes of different radicals in SCW were obtained. ·H was the most active free radical of reactions. This work is expected to understand the properties of free radicals in SCW better and explore intrinsic reaction mechanisms, which may provide a theoretical support for accomplishing efficient and low-carbon complete SCW gasification for hydrogen production. © 2024 Elsevier B.V.

关键词： Free radical Gasification Hydrogen production Reaction Supercritical Water (SCW)

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Enhancing thin film boiling heat transfer through electric field and surface Macro-Structure Synergy: Insights from bubble dynamics modulation

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International Journal of Heat and Mass Transfer 2025年 249卷

作者： He, Changqiu Tian, Jiameng Chen, Yiqi Zhu, Yuchen Liu, Xin Wang, Hai Wang, Zhentao Cai, Benan Wang, Changqing Wang, Junfeng Zhou, Zhifu Chen, Bin School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China School of Energy and Power Engineering Chongqing University Chongqing 400044 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Thermo-fluid Science and Nuclear Engineering School of Energy and Power Engineering Northeast Electric Power University Jilin 132012 China National Key Laboratory of Marine Engine Science and Technology Shanghai 201108 China

Improving boiling heat transfer in thin liquid films by employing external electrical fields and macro-structured surfaces presents promising for tackling the growing difficulties related to high-heat-flux thermal management in electronic devices. In this study, six distinct macro-structured surfaces are designed and fabricated to gain insight into how liquid film thickness, structural parameters, and applied voltage affect the efficiency of boiling heat transfer with ethanol as the coolant. High-speed imaging and precise heat transfer measurements are employed to characterize the boiling performance, providing insights into the underlying fundamentals driving the observed enhancements. Results reveal that applying a 4-kV voltage increases departure frequency of bubble by 86 % and a 28 % reduction in diameter, causing a 20 % improvement in critical heat flux (CHF). CHF is positively correlated with liquid film thickness and pin height, but negatively with pin spacing, achieving a 139 % increase under optimal conditions. Liquid film thickness was found to have the most significant impact on CHF, followed by pin spacing and applied voltage. By simplifying the void fraction equation, a new CHF correlation is proposed that introduces a dimensionless characteristic length, representing the relative effects between bubble size and film thickness, while accounting for the synergy between the electric field and surface macro-structure. © 2025 Elsevier Ltd

关键词： Electric heating

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Experimental Study on Supercritical Water Flooding in High Water Cut Heavy Oil Reservoirs

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2025年第5期46卷 1528-1533页

作者： Miao, Yan Zhao, Qiuyang Wang, Xuetao Lei, Yuhuan Gao, Yunbo Jin, Hui Guo, Liejin State Key Laboratory of Multiphase Flow Engineering Xi’an Jiaotong University Xi’an710049 China

Elevated water cut obstructs recovery of heavy oil in later stage of heavy oil reservoir exploitation. This paper simulates such scenarios using one-dimensional sandstone cores filled with saturated oil utilizing hot water flooding. Subsequently, we conducted indoor flooding tests for supercritical water flooding, high-pressure hot water flooding, and superheated steam flooding. Results reveal that supercritical water flooding yields the highest recovery rate (96.27%) and superior in-situ upgrading compared to hot water flooding and superheated steam flooding. The mechanism for enhancing oil recovery via 400◦C, 25 MPa supercritical water flooding in a high water cut heavy oil reservoir environment lies in the occurrence of thermal fluid breakthrough phenomenon, miscible flooding, and hydrothermal pyrolysis of heavy oil under supercritical water conditions. © 2025 Science Press. All rights reserved.

关键词： Petroleum reservoir evaluation

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Preparation, improvement, and application of metal–organic framework-based sensing materials for gas leakage and emission: A review

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Nano Materials Science 2025年

作者： Liu, Manyi Wang, Liang Ren, Shan Bai, Bofeng Chai, Shouning He, Chi Zheng, Chunli Yin, Xitao Li, Fengguang College of Materials Science and Engineering Chongqing University Chongqing400044 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Physics and Optoelectronic Engineering Ludong University Yantai264000 China School of Materials Science and Engineering Hubei University of Automotive Technology Shiyan442002 China

Industrial gas leaks and flue gas emissions pose significant threats to the safety of industrial operations and the atmospheric ecological environment. Traditional gas sensing materials often struggle to meet the challenges posed by complex industrial environments. Recently, metal-organic framework (MOF)-based gas sensing materials have garnered significant attention in industrial gas detection due to their high sensitivity, selectivity, and tunable properties. The exponential increase in related publications highlights the growing research interest in this field. This paper presents a comprehensive review of the advantages of various types of metal-organic frameworks and their derivatives for detecting industrial gas leaks and flue gas emissions, alongside an introduction of representative MOF synthesis methods. Furthermore, the primary sensing mechanisms of MOF-based gas sensing materials and strategies for enhancing the sensing performance are summarized. The current state of MOF-based gas sensing materials in industrial gas detection is also discussed. Finally, the potential limitations, existing challenges, and future directions of MOF-based industrial gas sensing materials are systematically analyzed, with suggestions for addressing these challenges to advance industrial gas detection technologies. © 2025 Chongqing University

关键词： Application Improvement Industrial gas detection MOF-Based sensing materials Preparation

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Research on control strategies for rapid load decrease events in fluoride salt reactor-supercritical CO2 Brayton cycle systems

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Nuclear engineering and Design 2025年 439卷

作者： Shichang, Yun Xinyu, Li Dalin, Zhang Ping, Song Wenxi, Tian Suizheng, Qiu Guanghui, Su State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Marine Thermal Power Technology Wuhan Second Ship Design and Research Institute Wuhan China

This study delves into the control strategies for the Fluoride-salt-cooled High-temperature Reactor-Supercritical CO2 (SCO2) Brayton cycle power generation system under rapid grid load reduction scenarios. By developing a dynamic simulation model, the system's dynamic response characteristics under rapid load changes were analyzed, and a combined control strategy emphasizing safety, speed, and economic efficiency was proposed. The research first compared the dynamic response characteristics and steady-state performance of different bypass configurations under load rejection conditions. The computational results indicate that all three bypass control systems exhibit excellent load-following capabilities, effectively responding to a 50 % load step change within 10 s. However, significant differences were observed in their steady-state thermodynamic performance: the upper cycle bypass control achieves the highest steady-state efficiency (η = 29.92 %), followed by the turbine bypass control (η = 27.50 %), with the heat source bypass control showing relatively lower efficiency (η = 26.49 %). Although the upper cycle bypass offers superior efficiency, it leads to a substantial increase in the working fluid flow through the compressor (ΔQ = 15 %) during operation, raising the risk of compressor blockage and necessitating additional flow restriction and anti-blocking interlock control systems. Considering system safety, control complexity, and engineering feasibility, the turbine bypass system, with its relative independence and lower operational risk, is deemed more suitable as the primary control strategy for load rejection conditions. Building on this, the study proposes a combined control strategy that leverages the strengths of both bypass control and inventory control. During the initial phase of rapid load reduction, the bypass control system quickly adjusts the turbine bypass valve opening to promptly respond to grid load changes, ensuring system frequency stability

关键词： Frequency stability

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Numerical Study of Multi-Factor Coupling Effects on Energy Conversion Performance of Nanofluidic Reverse Electrodialysis

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Frontiers in Heat and Mass Transfer 2025年第2期23卷 507-528页

作者： Hao Li Cunlu Zhao Jinhui Zhou Jun Zhang Hui Wang Yanmei Jiao Yugang Zhao School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing211816China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xi’an Jiaotong UniversityXi’an710049China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing210016China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai200093China Key Laboratory of Icing and Anti/De-icing China Aerodynamics Research and Development CenterMianyang621000China

Based on the rapid advancements in nanomaterials and nanotechnology,the Nanofluidic Reverse Electrodialysis(NRED)has attracted significant attention as an innovative and promising energy conversion strategy for extracting sustainable and clean energy fromthe salinity gradient ***,the scarcity of research investigating the intricate multi-factor coupling effects on the energy conversion performance,especially the trade-offs between ion selectivity and mass transfer in nanochannels,of NRED poses a great challenge to achieving breakthroughs in energy conversion *** numerical study innovatively investigates the multi-factor coupling effect of three critical operational factors,including the nanochannel configuration,the temperature field,and the concentration difference,on the energy conversion processes of *** this work,a dimensionless amplitude parameter s is introduced to emulate the randomly varied wall configuration of nanochannels that inherently occur in practical applications,thereby enhancing the realism and applicability of our *** results reveal that the application of a temperature gradient,which is oriented in opposition to the concentration gradient,enhances the ion transportation and selectivity simultaneously,leading to an enhancement in both output power and energy conversion ***,the increased fluctuation of the nanochannel wall from s=0 to s=0.08 improves ion selectivity yet raises ion transport resistance,resulting in an enhancement in output power and energy conversion efficiency but a slight reduction in ***,with increasing the concentration ratio cH/cL from 10 to 1000,either within a fixed temperature field or at a constant dimensionless amplitude,the maximumpower consistently attains its optimal value at a concentration ratio of 100 but the cation transfer number experiences amonotonic decrease across this entire range of concentration ***,uponmodifying the ope

关键词： Salinity gradient energy nanofluidic reverse electrodialysis energy conversion nanochannel configuration multi-factor coupling effect

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Large eddy simulation on the wake characteristics of linearly stratified flow past a sphere

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Scientific Reports 2025年第1期15卷 1-13页

作者： Xia, Tianci Wei, Na Shi, Liuliu School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 China Key Laboratory of Power Machinery and Engineering of Ministry of Education Shanghai Jiao Tong University Shanghai 200240 China

In this study, Large Eddy Simulation (LES) has been employed to examine the influence of the Froude number (Fr) on the linearly stratified wake and internal waves behind a sphere at a subcritical Reynolds number of Re = 3700. Six distinct sets of models with varying Fr (Fr = 0.05, 0.25, 0.5, 1, 2, ∞) have been chosen to establish density linear stratification through the use of a User Defined Function (UDF). The analysis focuses on the impact of stratification on wake characteristics, velocity distribution, and the structure of internal waves within stratified flow. It is evident that density stratification plays a pivotal role in shaping wake structure. Notably, in stratified flows, wakes exhibit unique characteristics including the generation of internal waves, suppression of vertical velocity, and the emergence of oscillating wake patterns. The study reveals that a decrease in the Froude number leads to heightened vertical suppression of the wake and increased anisotropy of the velocity distribution. Furthermore, as the Froude number ascends from 0.05 to 2, the wake undergoes a transition from quasi-two-dimensional vortex shedding to three-dimensional turbulence. © The Author(s) 2025.

关键词： Froude number Internal wave Linearly stratified flow Wake

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Enhancing the Frequency Control Stability in Large-Scale VPPs with Limited Capacity of Fast-Response Units 19th

Enhancing the Frequency Control Stability in Large-Scale VPP...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Liang, Jun Tian, Zeyu Zhang, Penghua Zhang, Mingyue Li, Wei Liu, Huan Chong, Daotong China Nuclear Power Operation Technology Co. Ltd. Hangzhou311215 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Nuclear Power Operation Management Co. Ltd. Jiaxing314300 China

ISBN: (纸本)9789819647996

As renewable energy penetration increases, Virtual power Plants (VPPs) must not only manage energy scheduling but also ensure system security, particularly in response to frequency fluctuations. Existing research focuses on optimizing Primary Frequency Control (PFC) and developing specific control strategies for VPP units. In this study, a dynamic simulation model of a VPP was constructed, and two control systems—Energy Management System (EMS) and Capacity Coordinated Frequency Control (CCFC)—were established and optimized for better control effectiveness. The results demonstrate that the EMS designed for rapid energy storage response is better than traditional methods in responding frequency disturbances caused by rapid power demand changes. Under EMS control, the frequency nadir improved by 17.5%, and the time to reach steady-state was reduced by 77.2% during rapid power increases. Similarly, the nadir improved by 17.1%, and the steady-state time was reduced by 69.5% during power decreases. In addition, the coordinated optimization of EMS and CCFC enhances the VPP’s ability to manage large-scale power fluctuations. The safe power step adaptation range is expanded from 5 MW to 25 MW when the BESS’s dispatchable power is limited. This study highlights the potential of integrated control strategies to significantly enhance the frequency regulation and overall stability of VPPs. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Frequency stability

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