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Perfect Double Roman Domination on Cographs
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作者 LI Peng XUE Xin-yi +1 位作者 LONG Yang-jing LI Xue-bo 《Chinese Quarterly Journal of Mathematics》 2025年第2期158-168,共11页
Consider a graph G=(V,E).A perfect double Roman dominating function(PDRDF for short)is a function h:V→{0,1,2,3}that satisfies the condition∑_(y∈NG[x],h(y)≥1)h(y)=|{y∈NG(x):h(y)≥1}|+2 for any x∈V with h(x)≤1.Th... Consider a graph G=(V,E).A perfect double Roman dominating function(PDRDF for short)is a function h:V→{0,1,2,3}that satisfies the condition∑_(y∈NG[x],h(y)≥1)h(y)=|{y∈NG(x):h(y)≥1}|+2 for any x∈V with h(x)≤1.The weightω(h)of this function is∑_(y∈V)h(y).The perfect double Roman domination number(PDRD-number)of G,denoted byγ_(dR)^(p)(G),is defined as the minimum weight among all PDRDFs of G.This article presents a comprehensive analysis of the PDRD-number of connected cographs,demonstrating that it falls within the set{2,3,4,5,6}.Furthermore,it establishes that for any integer i≥7,there is a connected cograph G such that its PDRD-number is equal to i. 展开更多
关键词 COGRAPHS double Roman domination Perfect double Roman domination
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Study on Sediment Removal Method of Reservoir Based on Double Branch Convolution
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作者 Hailong Wang Junchao Shi Xinjie Li 《Computers, Materials & Continua》 2025年第2期2951-2967,共17页
In response to the limitations and low computational efficiency of one-dimensional water and sediment models in representing complex hydrological conditions, this paper proposes a dual branch convolution method based ... In response to the limitations and low computational efficiency of one-dimensional water and sediment models in representing complex hydrological conditions, this paper proposes a dual branch convolution method based on deep learning. This method utilizes the ability of deep learning to extract data features and introduces a dual branch convolutional network to handle the non-stationary and nonlinear characteristics of noise and reservoir sediment transport data. This method combines permutation variant structure to preserve the original time series information, constructs a corresponding time series model, models and analyzes the changes in the outbound water and sediment sequence, and can more accurately predict the future trend of outbound sediment changes based on the current sequence changes. The experimental results show that the DCON model established in this paper has good predictive performance in monthly, bimonthly, seasonal, and semi-annual predictions, with determination coefficients of 0.891, 0.898, 0.921, and 0.931, respectively. The results can provide more reference schemes for personnel formulating reservoir scheduling plans. Although this study has shown good applicability in predicting sediment discharge, it has not been able to make timely predictions for some non-periodic events in reservoirs. Therefore, future research will gradually incorporate monitoring devices to obtain more comprehensive data, in order to further validate and expand the conclusions of this study. 展开更多
关键词 Prediction of reservoir sediment discharge double-branch convolution double prediction head deep learning
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基于Double Q-Learning的改进蝗虫算法求解分布式柔性作业车间逆调度问题
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作者 胡旭伦 唐红涛 《机床与液压》 北大核心 2025年第20期52-63,共12页
针对分布式柔性作业车间中存在的资源分配不均和调度稳定性不足问题,构建以最小化最大完工时间、机器总能耗和偏离度为目标的逆调度数学模型,提出一种基于Double Q-Learning的改进多目标蝗虫优化算法(DQIGOA)。针对该问题设计一种混合... 针对分布式柔性作业车间中存在的资源分配不均和调度稳定性不足问题,构建以最小化最大完工时间、机器总能耗和偏离度为目标的逆调度数学模型,提出一种基于Double Q-Learning的改进多目标蝗虫优化算法(DQIGOA)。针对该问题设计一种混合三层编码方式;提出一种基于逆调度特点的种群初始化方式以提高种群质量;引入权重平衡因子来提高非支配解存档中解集的多样性;将强化学习中的Double Q-Learning机制融入非支配解的选择过程,通过动态动作策略优化目标解的选取,提升调度方案的全局搜索能力与局部优化效率。最后构建26组算例,通过策略有效性分析证明了所提策略可显著提升DQIGOA算法的性能,并通过与NSGA-II、DE和SPEA-II算法进行对比证明DQIGOA算法的有效性。结果表明:相比NSGA-II、DE和SPEA-II算法,DQIGOA算法在HV、IGD、SP指标上均有优势,证明了DQIGOA能够有效提升解的收敛速度和多样性分布,在动态扰动条件下表现出更强的鲁棒性。 展开更多
关键词 分布式柔性作业车间 逆调度 蝗虫算法 double Q-Learning机制
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Boosting characteristic emissions of lanthanide in Cs_(2)Ag_(0.6)Na_(0.4)InCl_(6-x)Br_(x) double perovskites via mixing halide 被引量:2
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作者 Shujian Wang Dejian Chen +4 位作者 Jie Hu Sisi Liang Kunyuan Xu Maochun Hong Haomiao Zhu 《Journal of Rare Earths》 2025年第1期39-46,I0002,共9页
Lanthanide ions(Ln^(3+))doping provides a potential strategy to control over the luminescent properties of lead-free halide double perovskite nanocrystals(DP NCs).However,due to the low energy transfer efficiency betw... Lanthanide ions(Ln^(3+))doping provides a potential strategy to control over the luminescent properties of lead-free halide double perovskite nanocrystals(DP NCs).However,due to the low energy transfer efficiency between self-trapped exciton(STE)and Ln^(3+)ions,the characteristic emissions of Ln^(3+)ions are not prominent.Furthermore,the energy transfer mechanism between STE and Ln^(3+)ions is also elusive and requires in-depth study.We chose trace Bi^(3+)-doped Cs_(2)Ag_(0.6)Na_(0.4)InCl_(6-x)Br_(x) as a representative DP matrix to demonstrate that by tuning the bromide concentration,the Ln^(3+)emission can be greatly enhanced.Such enhanced STE and Ln^(3+)ions energy transfer originates from the high covalency of Ln-Br bond,which contributes to improve ment of the characteristic emission of Ln^(3+)ions.Furthermo re,optical spectroscopy reveals that the energy transfer mechanism from DP to Eu^(3+)ions is different from all the other doped Ln^(3+)ions.The energy transfer from DP to Eu^(3+)ions is mostly through Eu-Br charge transfer while the other Ln^(3+)ions are excited by energy transfer from STE.The distinct energy transfer mechanism has resulted from the energy separation between the excited energy level of Ln^(3+)ions and the bottom of conduction band of DP.With increasing the energy separation,the energy transfer from STE to Ln^(3+)ions is less efficient because of the generation of a larger number of phonons and finally becomes impossible for Eu^(3+)ions.Our results provide new insight into tuning the energy transfer of Ln^(3+)-doped DP NCs. 展开更多
关键词 double perovskitenanocrystal Lead free Lanthanideions Energytransfer Rare earths
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Analysis of wind-induced vibration response characteristics of multispan double-layer cable photovoltaic support structure 被引量:2
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作者 ZOU Lianghao WANG Jian +2 位作者 SONG Jie ZHOU Rui WANG Hao 《Journal of Southeast University(English Edition)》 2025年第1期37-43,共7页
To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃... To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃induced vibration response data of a three⁃span four⁃row double⁃layer cable PV support system.The wind⁃induced vibration characteristics with different PV module tilt angles,wind speeds,and wind direction angles were analyzed.The results showed that the double⁃layer cable large⁃span flexible PV support can effectively control the wind⁃induced vibration response and prevent the occur⁃rence of flutter under strong wind conditions.The maxi⁃mum value of the wind⁃induced vibration displacement of the flexible PV support system occurs in the windward first row.The upstream module has a significant shading effect on the downstream module,with a maximum effect of 23%.The most unfavorable wind direction angles of the structure are 0°and 180°.The change of the wind direction angle in the range of 0°to 30°has little effect on the wind vi⁃bration response.The change in the tilt angle of the PV modules has a greater impact on the wind vibration in the downwind direction and a smaller impact in the upwind di⁃rection.Special attention should be paid to the structural wind⁃resistant design of such systems in the upwind side span. 展开更多
关键词 double⁃layer cable photovoltaic support aero⁃elastic model wind tunnel test wind⁃induced vibration re⁃sponse
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Hemoglobin glycation index among adults with type 1 diabetes:Association with double diabetes features 被引量:1
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作者 Xiao-Lin Ji Min Yin +5 位作者 Chao Deng Li Fan Yu-Ting Xie Fan-Su Huang Yan Chen Xia Li 《World Journal of Diabetes》 2025年第4期153-165,共13页
ACKGROUND The hemoglobin glycation index(HGI)represents the discrepancy between the glucose management indicator(GMI)based on mean blood glucose levels and laboratory values of glycated hemoglobin(HbA1c).The HGI is a ... ACKGROUND The hemoglobin glycation index(HGI)represents the discrepancy between the glucose management indicator(GMI)based on mean blood glucose levels and laboratory values of glycated hemoglobin(HbA1c).The HGI is a promising indicator for identifying individuals with excessive glycosylation,facilitating personalized evaluation and prediction of diabetic complications.However,the factors influencing the HGI in patients with type 1 diabetes(T1D)remain unclear.Autoimmune destruction of pancreaticβcells is central in T1D pathogenesis,yet insulin resistance can also be a feature of patients with T1D and their coexistence is called“double diabetes”(DD).However,knowledge regarding the relationship between DD features and the HGI in T1D is limited.AIM To assess the association between the HGI and DD features in adults with T1D.METHODS A total of 83 patients with T1D were recruited for this cross-sectional study.Laboratory HbA1c and GMI from continuous glucose monitoring data were collected to calculate the HGI.DD features included a family history of type 2 diabetes,overweight/obesity/central adiposity,hypertension,atherogenic dyslipidemia,an abnormal percentage of body fat(PBF)and/or visceral fat area(VFA)and decreased estimated insulin sensitivity.Skin autofluorescence of advanced glycation end products(SAF-AGEs),diabetic complications,and DD features were assessed,and their association with the HGI was analyzed.RESULTS A discrepancy was observed between HbA1c and GMI among patients with T1D and DD.A higher HGI was associated with an increased number of SAF-AGEs and a higher prevalence of diabetic microangiopathy(P=0.030),particularly retinopathy(P=0.031).Patients with three or more DD features exhibited an eight-fold increased risk of having a high HGI,compared with those without DD features(adjusted odds ratio=8.12;95%confidence interval:1.52-43.47).Specifically,an elevated PBF and/or VFA and decreased estimated insulin sensitivity were associated with high HGI.Regression analysis identified estimated insulin sensitivity and VFA as factors independently associated with HGI.CONCLUSION In patients with T1D,DD features are associated with a higher HGI,which represents a trend toward excessive glycosylation and is associated with a higher prevalence of chronic diabetic complications. 展开更多
关键词 Type 1 diabetes double diabetes Insulin resistance Hemoglobin glycation index Advanced glycation end products Diabetic complications
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Optimal Production Capacity Matching for Blockchain-Enabled Manufacturing Collaboration With the Iterative Double Auction Method 被引量:1
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作者 Ying Chen Feilong Lin +2 位作者 Zhongyu Chen Changbing Tang Cailian Chen 《IEEE/CAA Journal of Automatica Sinica》 2025年第3期550-562,共13页
The increased demand for personalized customization calls for new production modes to enhance collaborations among a wide range of manufacturing practitioners who unnecessarily trust each other.In this article,a block... The increased demand for personalized customization calls for new production modes to enhance collaborations among a wide range of manufacturing practitioners who unnecessarily trust each other.In this article,a blockchain-enabled manufacturing collaboration framework is proposed,with a focus on the production capacity matching problem for blockchainbased peer-to-peer(P2P)collaboration.First,a digital model of production capacity description is built for trustworthy and transparent sharing over the blockchain.Second,an optimization problem is formulated for P2P production capacity matching with objectives to maximize both social welfare and individual benefits of all participants.Third,a feasible solution based on an iterative double auction mechanism is designed to determine the optimal price and quantity for production capacity matching with a lack of personal information.It facilitates automation of the matching process while protecting users'privacy via blockchainbased smart contracts.Finally,simulation results from the Hyperledger Fabric-based prototype show that the proposed approach increases social welfare by 1.4%compared to the Bayesian game-based approach,makes all participants profitable,and achieves 90%fairness of enterprises. 展开更多
关键词 Blockchain iterative double auction manufacturing collaboration production capacity matching
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CO_(2)-H_(2)O co-electrolysis to CO/O_(2) for safe oxidative double carbonylation of ethylene/acetylene
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作者 Yanwei Cao Yunhao Qu +5 位作者 Bin Su Gongwei Wang Yang Huang Zhenmin Luo Lin Zhuang Lin He 《Chinese Journal of Catalysis》 2025年第7期202-210,共9页
Upgrading carbon dioxide(CO_(2))into value-added bulk chemicals offers a dual-benefit strategy for the carbon neutrality and circular carbon economy.Herein,we develop an integrated CO_(2) valorization strategy that sy... Upgrading carbon dioxide(CO_(2))into value-added bulk chemicals offers a dual-benefit strategy for the carbon neutrality and circular carbon economy.Herein,we develop an integrated CO_(2) valorization strategy that synergizes CO_(2)-H_(2)O co-electrolysis(producing CO/O_(2) feeds)with oxidative double carbonylation of ethylene/acetylene to synthesize CO_(2)-derived C_(4) diesters(dimethyl succinate,fumarate,and maleate).A group of versatile building blocks for manufacturing plasticizers,biodegradable polymers,and pharmaceutical intermediates.Remarkably,CO_(2) exhibits dual functionality:serving simultaneously as a CO/O_(2) source and an explosion suppressant during the oxidative carbonylation process.We systematically investigated the explosion-suppressing efficacy of CO_(2) in flammable gas mixtures(CO/O_(2),C_(2)H_(4)/CO/O_(2),and C_(2)H_(2)/CO/O_(2))across varying concentrations.Notably,the mixed gas stream from CO_(2)/H_(2)O co-electrolysis at an industrial-scale current densities of 400 mA/cm^(2),enabling direct utilization in oxidative double carbonylation reactions with exceptional compatibility and inherent safety.Extended applications were demonstrated through substrate scope expansion and gram-scale synthesis.This study establishes not only a safe protocol for oxidative carbonylation processes,but also opens an innovative pathway for sustainable CO_(2) valorization,including CO surrogate and explosion suppressant. 展开更多
关键词 Carbon dioxide ELECTROLYSIS Explosion suppressant double Carbonylation Explosion limits ETHYLENE ACETYLENE
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Double response reversible phosphorescence based on cyclodextrin supramolecular flexible elastic achieved multicolor delayed fluorescence
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作者 Linnan Jiang Zhenkai Qian +7 位作者 Yong Chen Xiaoyong Yu Yugui Qiu Wen-Wen Xu Yonghui Sun Xiufang Xu Lihua Wang Yu Liu 《Chinese Chemical Letters》 2025年第8期315-321,共7页
Purely organic room-temperature phosphorescence(RTP)is current hotspot in the research fields of chemistry,biology,materials etc.Herein,we report that photo-thermal double response reversible ultralong RTP flexible el... Purely organic room-temperature phosphorescence(RTP)is current hotspot in the research fields of chemistry,biology,materials etc.Herein,we report that photo-thermal double response reversible ultralong RTP flexible elastic material with multicolor delayed fluorescence,which is constructed by 4-biphenylboronic acid(BOH),polyethylene glycol,2,2-bis(hydroxymethyl)propionic acid,isophorone diamine and isophorone diisocyanate copolymer.Importantly,the supramolecular phosphorescent elastomer not only exhibits extending RTP emission with a lifetime up to 1.21 s,but also gives a visible afterglow of 20 s via encapsulation of BOH unities by the deep cavities of hydroxypropyl-β-cyclodextrin(β-CD-HP)and in situ polymerization.Especially,after doping organic dyes(Fluorescein isothiocyanate,Sulforhodamine 101,Rhodamine B),supramolecular phosphorescent elastomer achieves multicolor delayed fluorescence realized by RTP energy transfer from phosphorescent donor to dye acceptors,which possesses reversible photo-thermal responsiveness and maintains high efficiency in delayed emission even after dozens of cycles.Present research provides a new approach for constructing multicolor delayed fluorescent supramolecular elastomers. 展开更多
关键词 double response reversible CYCLODEXTRIN RTP Host-vipinteraction Flexibleelastic
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Insight into physical properties of lutetium-based double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb and Ta)
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作者 Saber Saad Essaoud Said Al Azar +3 位作者 Ahmad A.Mousa Anas Y.Al-Reyahi Nabil Al Aqtash Mohammed Elamin Ketfi 《Journal of Rare Earths》 2025年第1期199-208,I0008,共11页
Based on the density functional theory,the double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb,and Ta)were studied to predict their structural,thermodynamic,thermoelectric,and optical characteristics.All the considered ... Based on the density functional theory,the double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb,and Ta)were studied to predict their structural,thermodynamic,thermoelectric,and optical characteristics.All the considered alloys are thermodynamically stable and have semiconductor behavior with indirect band gaps of 0.62,0.75,and 0.8 eV for LuVCo_(2)Bi_(2),LuNbCo_(2)Bi_(2),and LuTaCu_(2)Bi_(2),respectively.The investigated compounds exhibit semiconducting behavior with energy gaps below 0.8 eV.The impact of heat and pressure on thermodynamic coefficients was evaluated,and the influence of charge carriers on the temperature-dependent properties was studied using the semi-classical Boltzmann model.The studied compounds were characterized by their low lattice thermal conductivity at room temperature and low thermal expansion coefficient.These alloys exhibit substantial absorption coefficients in the ultraviolet(UV)light region,high optical conductivity,and high reflectivity in the visible light region,making them highly appealing materials for applications in the energy and electronics sectors. 展开更多
关键词 double half-Heusler Abinitio calculation Optical coefficients THERMOELECTRICITY Lattice thermal conductivity RAREEARTHS
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An environmentally friendly synthesis route:Low-temperature preparation of vacancy-ordered double perovskites Cs_(2)SnX_(6)(X=Cl,Br,I)via ionic liquid
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作者 Yuxin Huang Yibo Cui +2 位作者 Qipeng Lu Xin Liu Lijie Zhu 《International Journal of Minerals,Metallurgy and Materials》 2025年第10期2572-2578,共7页
Lead-free vacancy-ordered double perovskites have emerged as promising materials for optoelectronic applications due to their environmentally friendly characteristics and exceptional properties.However,conventional sy... Lead-free vacancy-ordered double perovskites have emerged as promising materials for optoelectronic applications due to their environmentally friendly characteristics and exceptional properties.However,conventional synthesis methods often depend on toxic reagents and stringent conditions,limiting their large-scale synthesis and practical application.In this work,an environmentally friendly synthesis route was proposed for preparing vacancy-ordered double perovskites Cs_(2)SnX_(6)(X=Cl,Br,and I)with high crystallinity under low-temperature and ambient-pressure conditions.This method utilizes ion liquid(i.e.,1-butyl-3-methylimidazolium chloride([Bmim]Cl),1-butyl-3-methylimidazolium bromide([Bmim]Br)and 1-butyl-3-methylimidazolium iodide([Bmim]I))in combination with saturated aqueous solutions of ammonium halides as solvents,replacing traditional hydrogen halide acid or polar organic solvents.Experimental and characterization results demonstrate that the Cs_(2)SnX_(6)(X=Cl,Br,and I)possess high crystallinity,well-defined morphology,and improved thermal stability.These improvements are attributed to the hydrogen bonding interactions between ionic liquids and the perovskite precursors.Additionally,the halogen-rich environment provided by ionic liquids and ammonium halide salts facilitates defect passivation.Furthermore,this method is applicable to the synthesis of doped perovskite crystals,demonstrated by the successful synthesis of Bi-doped Cs_(2)SnCl_(6) crystals with a photoluminescence quantum efficiency of 12.73%.This study presents a novel strategy for synthesizing high-quality vacancy-ordered double perovskites and their doping or alloyed compounds. 展开更多
关键词 perovskite vacancy-ordered double perovskites LEAD-FREE low temperature ionic liquids green synthesis
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Double-vacancy-induced polarization and intensified built-in electric field in S-Scheme heterojunction for removal of antibiotics and Cr (VI)
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作者 Xiangyang Zheng Jinwang Wu Haifeng Shi 《Chinese Journal of Catalysis》 2025年第9期50-64,共15页
Antibiotics and heavy metals usually co-exist in wastewater and pose serious environmental hazards.Herein,a series of VMo-BMO/O_(v)-BOB S-scheme heterojunctions with double vacancy(Mo vacancy and photoexcited O vacanc... Antibiotics and heavy metals usually co-exist in wastewater and pose serious environmental hazards.Herein,a series of VMo-BMO/O_(v)-BOB S-scheme heterojunctions with double vacancy(Mo vacancy and photoexcited O vacancy)were constructed via an electrostatic assembly method.The removal efficiency of Cr(VI)and tetracycline(TC)over VMo-BMO/O_(v)-BOB-0.3 was 2.47 and 1.13 times than that of a single system,respectively.In-situ EPR demonstrated that the surface O vacancies could be generated under LED light irradiation.These photoexcited O vacancies(P-O_(v))enabled VMo-BMO/O_(v)-BOB composites still exhibit satisfactory activity after five successive cycles and an amplified Fermi level gap.The enhancement could be attributed to the enhanced internal electric field and double-vacancy-induced polarization.Additionally,the density functional theory calculation results suggested that double vacancy induced polarization electric field increases the dipole moment,which was conducive to rapid electron transport.Photoluminescence and time-resolved photoluminescence analysis demonstrated that the introduction of S-scheme heterojunction and double vacancy promoted charge transfer and prolonged the lifetime of carriers.Degradation intermediates and toxicity of products were evaluated.In conclusion,a possible mechanism based on VMo-BMO/O_(v)-BOB S-scheme heterojunction in the simultaneous removal of Cr(VI)and TC was proposed. 展开更多
关键词 Photocatalysis S-scheme heterojunction double vacancy Polarization Fermi level
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UV-light-promoted synthesis of a double Z-scheme BN/C_(60)/g-C_(3)N_(4) heterojunction with enhanced photodegradation performance for antibiotics
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作者 Yong Guo Haoran Xu +1 位作者 Shugui Hua Zixuan Xu 《Journal of Environmental Sciences》 2025年第9期686-700,共15页
Developing environmental-friendly non-metal photocatalysts for the efficient removal of antibiotics from environment is a significant challenge.The construction of heterojunction is regarded as a powerful strategy to ... Developing environmental-friendly non-metal photocatalysts for the efficient removal of antibiotics from environment is a significant challenge.The construction of heterojunction is regarded as a powerful strategy to enhance the photodegradation efficiency of photocatalysts for pollutants,being due that this strategy can effectively suppress the recombination of the photo-induced electron and hole.In this research,a novel double Z-scheme BN/C_(60)/g-C_(3)N_(4) heterojunction was successfully synthesized via one-step synthetic approach.Based on a series of experimental characterization,BN/C_(60)/g-C_(3)N_(4) is most likely formed via the interaction between N element of BN and g-C_(3)N_(4) with C_(60) under UV-light irradiation.The band structures of BN,C_(60),g-C_(3)N_(4) and the internal electric field among them suggest that BN/C_(60)/g-C_(3)N_(4) may has a direct double z-type band arrangement,which facilitates efficient charge transfer.The photodegradation rate of BN/C_(60)/g-C_(3)N_(4) for tetracycline reached 90.1%,which is 2.9 times higher than that observed with BN and 2.3 times higher than that of g-C_(3)N_(4).BN/C_(60)/g-C_(3)N_(4) exhibits remarkable photocatalytic performance across a wide pH range and in the influence of different anions.This study offers significant insights about how to design double z-scheme metal-free photocatalyst with high photodegradation efficiency for antibiotic. 展开更多
关键词 BN Graphic carbon nitride double Z-scheme PHOTODEGRADATION Antibiotic
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Double Reduction in China:Demand-Supply Mismatch,On-Campus Substitution,and Policy Rebalancing
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作者 Xinghe Fang 《Journal of Contemporary Educational Research》 2025年第10期346-349,共4页
This review takes stock of China’s Double Reduction.In the short run,it lowered visible burden and pushed demand from subject tutoring toward on-campus and non-subject services.But with high-stakes selection unchange... This review takes stock of China’s Double Reduction.In the short run,it lowered visible burden and pushed demand from subject tutoring toward on-campus and non-subject services.But with high-stakes selection unchanged,demand reappears as small-group/one-to-one provision,advantaging families with high socioeconomic status and strong schools.Lasting relief will require tighter oversight and admissions reform with targeted,well-funded in-school support. 展开更多
关键词 double Reduction Shadow education After-school services Demand rigidity EQUITY Income heterogeneity
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Film thickness effect on 2D lead-free hybrid double perovskite properties: Band gap, photocurrent and stability
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作者 Mohamed Saber Lassoued Faizan Ahmad Yanzhen Zheng 《Chinese Chemical Letters》 2025年第4期449-454,共6页
Lead-free hybrid double perovskites(LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic pr... Lead-free hybrid double perovskites(LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic properties has not yet been investigated. Herein, we synthesized two new Ruddlesden–Popper LFHDPs, namely(C_(5)H_(12)N)_(4)AgBiI_(8)(CAB-1) and(C_(6)H_(14)N)_(4)Ag Bi I8(CAB-2) using cyclopentylamine and cyclohexylamine as monoamine ligands. Indeed, these two Ag(Ⅰ)-Bi(Ⅲ) LFHDPs form smooth and uniform films ranging in thickness from 250 nm to 1 μm, with preferred orientations. Notably, the studies on the optical properties showed that the direct band gap value decreased from 2.17 e V to 1.91 e V for CAB-1 and from 2.05 e V to 1.86 e V for CAB-2 with increasing thickness. Accordingly, photo-current response using a xenon lamp revealed a significant difference of over 1000 n A between light and dark conditions for1 μm-thickness films, suggesting potential for light harvesting. Other than that, thicker films of CAB-1and CAB-2 exhibit high stability for 90 days in a relatively humid environment(RH of 55%), paving the way for promising optoelectronic applications. 展开更多
关键词 LEAD-FREE double perovskites Film thickness Photocurrent response High stability
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Effective suppression of surface cation segregations on double perovskite oxides through entropy engineering
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作者 Zhe Wang Mengke Yuan +5 位作者 Juntao Gao Hongru Hao Jingwei Li Lingling Xu Zhe Lv Bo Wei 《Journal of Rare Earths》 2025年第2期345-353,I0005,共10页
Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been... Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been widely studied as an active cathode but still suffer from serious detrimental segregations.To enhance the cathode stability,a PBCC derived A-site medium-entropy Pr_(0.6)La_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Ba_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(ME-PBCC)oxide was prepared and its segregation behaviors were investigated under different conditions.Compared with initial PBCC oxide,the segregations of BaO and Co_(3)O_(4)on the surface of ME-PBCC material are significantly suppressed,especially for Co_(3)O_(4),which is attributed to its higher configuration entropy.Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material,enabling it as a promising cathode for SOFCs. 展开更多
关键词 Solid oxide fuel cells CATHODE double perovskite Configuration entropy Cation segregation Rare earths
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A sterically-hindered organic molecule to modulate hydrogen bonding and the electrical double layer for highly reversible zinc anodes
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作者 Rongsheng Guo Yongfeng Huang +5 位作者 Chang Shu Rui Yao Yifu Gao Wenbao Liu Zhichun Si Feiyu Kang 《Journal of Energy Chemistry》 2025年第6期280-291,I0007,共13页
The practical application of emerging rechargeable aqueous zinc(Zn)batteries is challenged by the poor reversibility and cycling stability of Zn anodes,primarily due to parasitic side reactions.While numerous strategi... The practical application of emerging rechargeable aqueous zinc(Zn)batteries is challenged by the poor reversibility and cycling stability of Zn anodes,primarily due to parasitic side reactions.While numerous strategies have been proposed,balancing the suppression of side reactions with the maintenance of fast Zn plating/stripping kinetics remains a significant challenge.In this study,sucrose,a sterically-hindered organic molecule with abundant hydroxyl groups,is employed to suppress the side reactions and maintain the moderate kinetics of Zn plating/stripping by modulating the hydrogen bond network without altering the Zn^(2+)solvation structure.Its steric hindrance effect further impedes the lateral diffusion of Zn atoms on the electrode surface within the electric double layer,effectively mitigating dendrite growth and stabilizing the electrodeposition process.Consequently,the formulated Suc/ZnSO_(4)electrolyte achieves a remarkably Coulombic efficiency of 99.90% over 2600 cycles at 3 mA cm^(-2)for 1 mAh cm^(-2)in Zn‖Cu cells.The enhanced Zn anode reversibility leads to excellent cycling stability in Zn‖LiFePO_(4)cells and Zn‖β-MnO_(2)cells.This study underscores the potential of sterically-hindered organic molecule strategies to enhance Zn anode stability while maintaining favorable Zn deposition/stripping dynamics in aqueous Zn batteries. 展开更多
关键词 Organic molecule Steric effect Interfacial dynamics Hydrogen bonding Electrical double layer Zinc anodes
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Reorientation of hydraulic fractures and stress-shadow effect in double-well fracturing of hydrocarbon reservoirs:3D numerical model and analysis
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作者 Yang Ju Yang Li +1 位作者 Yongming Yang Yongliang Wang 《International Journal of Mining Science and Technology》 2025年第4期499-517,共19页
Multistage fracturing technology has been used to enhance tight hydrocarbon resource recovery.Determining the proper well spacing and fracturing strategy is crucial for generating a complex fracture network that facil... Multistage fracturing technology has been used to enhance tight hydrocarbon resource recovery.Determining the proper well spacing and fracturing strategy is crucial for generating a complex fracture network that facilitates oil and gas flow in reservoirs.The stress-shadow effect that occurs between multiple wells significantly affects the development of fracture networks in reservoirs.However,the quantification of the stress-shadow effect and its influence on fracture networks has not been satisfactorily resolved because of the difficulties in detecting and identifying fracture propagation and reorientation in reservoirs.In this study,based on the geological information from the Shengli oilfield,we applied a hybrid finite element-discrete element method to analyze engineering-scale three-dimensional fracture propagation and reorientation by altering well spacings and fracturing strategies.The results indicate that the fracturing area generated by the synchronous fracturing scheme is much smaller than those generated by the sequential and alternative schemes.An alternative hydrofracturing scheme is optimal with respect to fracturing area.The stress-blind area was defined to quantify the mechanical disturbance between adjacent wells.Our study improves the understanding of the effect of fracturing schemes on fracture networks and the impact of independent factors contributing to stress-shadow effects. 展开更多
关键词 Multistage fracturing double wells Stress-shadow effect Fracturing strategies 3D reorientation Engineering-scale model
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Engineering living root with mechanical stimulation derived from reciprocating compression in a double network hydrogel as elastic soil
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作者 Qiye Wu Jinchun Xie +1 位作者 Junfu Li Yongjun Men 《Advanced Agrochem》 2025年第2期123-131,共9页
The root system actively reacts to mechanical stimuli in its environment,transmitting mechanical signals to optimize the utilization of environmental resources.While the mechanical impedance created by the growth medi... The root system actively reacts to mechanical stimuli in its environment,transmitting mechanical signals to optimize the utilization of environmental resources.While the mechanical impedance created by the growth medium serves as the primary source of stimulation for the roots,extensive research has focused on the roots'response to static mechanical stimulation.However,the impact of dynamic mechanical stimulation on root phenotype remains underexplored.In this study,we utilized a low acyl gellan gum/polyacrylamide(GG/PAM)double network elastic hydrogel as the growth medium for rapeseed.We constructed a mechanical device to investigate the effects of reciprocating extrusion stimulation on the growth of the rapeseed root system.After three weeks of mechanical stimulation,the root system exhibited a significant increase in lateral roots.This branching enhanced the roots'anchoring and penetration into the hydrogel,thereby improving the root system's adaptability to its environment.Our findings offer valuable data and insights into the effects of reciprocating mechanical stimulation on root growth,providing a new way for engineering root phenotype. 展开更多
关键词 Mechanical stimulation Hydrogel medium double network hydrogel Root phenotype Rapeseed growth Elastic soil
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Regulating electric double layer in non-fluorinated ether electrolyte enables high-voltage and low-temperature lithium metal batteries
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作者 Renfei Zhao Yuanhang Gao +7 位作者 Zuosu Qin Yuelin Li Tao Zhang Anqiang Pan Ning Zhang Renzhi Ma Xiaohe Liu Gen Chen 《Advanced Powder Materials》 2025年第3期110-119,共10页
The poor oxidation stability of ether-based solvents has long been a major challenge limiting their practical application.To enhance the oxidative stability of ether-based electrolytes,the physicochemical properties o... The poor oxidation stability of ether-based solvents has long been a major challenge limiting their practical application.To enhance the oxidative stability of ether-based electrolytes,the physicochemical properties of various glycol dimethyl ethers are screened,and diglyme(G2)is selected as the sole solvent for the electrolyte.Lithium bis(fluorosulfonyl)imide(LiFSI),a highly dissociative salt,is used as the primary salt;while lithium nitrate(LiNO_(3))and lithium difluorophosphate(LiDFP),which have small ionic sizes and strong binding energies,are added as secondary salts.The resulting electrolyte can modulate the electric double layer structure by NO_(3)^(-) and DFP^(-) on the cathode side,leading to an increased Liþconcentration that is originally repelled by the cathode.Additionally,the oxidation stability of the electrolyte is improved and the formed electrode-electrolyte interphase is more uniform and stable,thereby enhancing the electrochemical performance of the cells.As a result,cells assembled with a total of 1 M ternary lithium salts in G2 solvent can operate at high voltage of 4.4 V.The LijjNCM811 cells maintain 80.2%capacity retention after 270 cycles at room temperature,with an average Coulombic efficiency of 99.5%,and exhibit 88.4%capacity retention after 200 cycles at -30℃. 展开更多
关键词 Lithium metal battery Ether electrolyte Electric double layer High voltage LOW-TEMPERATURE
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