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
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
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
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
Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structur...Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structural studies of other physicochemical properties are con-ducted on a series of materials obtained by the sol-gel method with different ratios of Gd and Sm cations.It is documented that changing the x value,and the resulting adjustment of the average ionic radius,have a significant impact on the crystal structure,stability,as well as on the total conductivity and thermomechanical properties of the materials,with the best results obtained for the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)composition.Oxygen electrodes are prepared using the selected compound,allowing to obtain low polarization resistance values,such as 0.086Ω·cm^(2)at 800℃.Systematic studies of electrocatalytic activity are conducted using La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(_(0.2))O_(3−δ)as the electrolyte for all electrodes,and Ce_(0.8)Gd_(0.2)O_(2−δ)electrolyte for the best performing Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes.The electrochemical data are analyzed using the distribution of relaxation times method.Also,the influence of the preparation method of the electrode material is in-ve`stigated using the electrospinning technique.Finally,the performance of the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes is tested in a Ni-YSZ(yttria-stabilized zirconia)anode-supported cell with a Ce_(0.8)Gd_(0.2)O_(2−δ)buffer layer,in the fuel cell and electrolyzer operating modes.With the electrospun electrode,a power density of 462 mW·cm^(−2)is obtained at 700℃,with a current density of ca.0.2 A·cm^(−2)at 1.3 V for the electrolysis at the same temperature,indicating better performance compared to the sol-gel-based electrode.展开更多
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
Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIG...Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIGS.One of the reasons is the high recombination rate of carriers at the interface.In this paper,in order to reduce the carrier recombination,a new solar cell structure with double absorber layers of Al-doped ZnO(AZO)/intrinsic(i)-ZnO/CdS/CZTS_(x1)Se_(1−x1)(CZTSSe_(1))/CZTS_(x2)Se_(1−x2)(CZTSSe_(2))/Mo was proposed,and the optimal conduction band offsets(CBOs)of CdS/CZTSSe_(1) interface and CZTSSe_(1)/CZTSSe_(2) interface were determined by changing the S ratio in CZTSSe_(1) and CZTSSe_(2),and the effect of thickness of CZTSSe_(1) on the performance of the cell was studied.The efficiencies of the optimized single and double absorber layers reached 17.97%and 23.4%,respectively.Compared with the single absorber layer structure,the proposed structure with double absorber layers has better cell performance.展开更多
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
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
Non-aqueous emulsions have a wide range of applications in cosmetics,drug-controlled release,and the preparation of functional nanoparticles.However,due to the weaker polarity of non-aqueous solvents,these emulsions o...Non-aqueous emulsions have a wide range of applications in cosmetics,drug-controlled release,and the preparation of functional nanoparticles.However,due to the weaker polarity of non-aqueous solvents,these emulsions often exhibit inferior stability compared to their aqueous counterparts.In this experiment,the properties of quaternary ammonium surfactants in glycerol were investigated through surface tension measurements,to further enhance the stability of n-decane/glycerol emulsions,hydrophilic nanoparticles SiO_(2) were modified in situ using double tailed quaternary ammonium surfactants Di-C_(12)DAB and Di-C_(16)DAB.Stable n-decane/glycerol Pickering emulsions were successfully prepared.These emulsions were stable at 45℃for over six months,and no significant changes in droplet size occurred.The minimum droplet size of the emulsion was only 2-3μm.Contact angle measurements showed that the wettability of the silica surface was tremendously affected by the concentration and the alkyl chain length of the double-tailed surfactants.In the presence of Di-C_(12)DAB,the contact angle of glycerol on the silica surface increased monotonically with the surfactant concentration.This explains the phenomenon that the Pickering emulsions containing Di-C_(12)DAB and silica particles were stable within the contact angle range of 80°-120°.Comparatively,the contact angle of the glycerol on the silica surface in the presence of Di-C_(16)DAB first increased with surfactant concentrations and then decreased,reaching a maximum at 0.6 mmol/L.It can be concluded that Di-C_(12)DAB formed monolayers at the surface of silica particles within all investigated concentrations.On the contrary,Di-C_(16)DAB formed monolayers at concentrations below 0.6 mmol/L and formed double layers at concentrations above 0.6 mmol/L,leading to a non-monotonic change in the contact angle with respect to concentration.Using these stable non-aqueous Pickering emulsions as templates,polymer microspheres with a particle size of 2-3μm were successfully prepared with high yield.This work is helpful to expand the potential applications of non-aqueous emulsions in the encapsulation of drug,controlled release,material preparation,and cosmetic formulations.展开更多
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
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
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
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
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
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
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
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
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
基金Supported by the National Natural Science Foundation Youth Fund of China(Grant No.11701059)The Chongqing Natural Science Foundation Innovation and Development Joint Fund(Municipal Education Commission)(Grant No.CSTB2022NSCQ-LZX0003)The Open Research Fund of Key Laboratory of Nonlinear Analysis&Applications(Central China Normal University),Ministry of Education,P.R.China。
文摘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.
基金NationalNatural Science Foundation of China(U2243236,51879115,U2243215),Recipients of funds:Xinjie Li,URL:https://www.nsfc.gov.cn/(accessed on 25 November 2024).
文摘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.
基金Project supported by the Research Project of Mindu Innovation Laboratory(2021ZZ114)Natural Science Foundation of Xiamen(3502Z20227255)+1 种基金Major Research Project of Xiamen(3502Z20191015)the Science and Technology Major Project of Fujian Province(2021HZ021013)。
文摘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.
基金The National Natural Science Foundation of China(No.52338011).
文摘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.
基金funded by the National Science Centre,Poland,on the basis of the decision number UMO-2020/37/B/ST8/02097supported by the program“Excellence Initiative-Research University”for the AGH University of Krakow(IDUB AGH,No.501.696.7996,Action 4,ID 9880).
文摘Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structural studies of other physicochemical properties are con-ducted on a series of materials obtained by the sol-gel method with different ratios of Gd and Sm cations.It is documented that changing the x value,and the resulting adjustment of the average ionic radius,have a significant impact on the crystal structure,stability,as well as on the total conductivity and thermomechanical properties of the materials,with the best results obtained for the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)composition.Oxygen electrodes are prepared using the selected compound,allowing to obtain low polarization resistance values,such as 0.086Ω·cm^(2)at 800℃.Systematic studies of electrocatalytic activity are conducted using La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(_(0.2))O_(3−δ)as the electrolyte for all electrodes,and Ce_(0.8)Gd_(0.2)O_(2−δ)electrolyte for the best performing Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes.The electrochemical data are analyzed using the distribution of relaxation times method.Also,the influence of the preparation method of the electrode material is in-ve`stigated using the electrospinning technique.Finally,the performance of the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes is tested in a Ni-YSZ(yttria-stabilized zirconia)anode-supported cell with a Ce_(0.8)Gd_(0.2)O_(2−δ)buffer layer,in the fuel cell and electrolyzer operating modes.With the electrospun electrode,a power density of 462 mW·cm^(−2)is obtained at 700℃,with a current density of ca.0.2 A·cm^(−2)at 1.3 V for the electrolysis at the same temperature,indicating better performance compared to the sol-gel-based electrode.
基金supported by the National Natural Science Foundation of China (Nos. 22375157 and W2433042)the Key Scientific and Technological Innovation Team of Shaanxi Province(No. 2020TD-001)+1 种基金the Fundamental Research Funds for Central Universities, State Key Laboratory of Electrical Insulation and Power Equipment (No. EIPE23409)the Instrument Analysis Center of Xi’an Jiaotong University for assistance。
文摘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.
基金supported by the Science and Technology Innovation Development Program(No.70304901).
文摘Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is considered to be the most potential light-absorbing material to replace CuInGaSe_(2)(CIGS),but the actual photoelectric conversion efficiency of such cells is much lower than that of CIGS.One of the reasons is the high recombination rate of carriers at the interface.In this paper,in order to reduce the carrier recombination,a new solar cell structure with double absorber layers of Al-doped ZnO(AZO)/intrinsic(i)-ZnO/CdS/CZTS_(x1)Se_(1−x1)(CZTSSe_(1))/CZTS_(x2)Se_(1−x2)(CZTSSe_(2))/Mo was proposed,and the optimal conduction band offsets(CBOs)of CdS/CZTSSe_(1) interface and CZTSSe_(1)/CZTSSe_(2) interface were determined by changing the S ratio in CZTSSe_(1) and CZTSSe_(2),and the effect of thickness of CZTSSe_(1) on the performance of the cell was studied.The efficiencies of the optimized single and double absorber layers reached 17.97%and 23.4%,respectively.Compared with the single absorber layer structure,the proposed structure with double absorber layers has better cell performance.
基金Supported by the National Key R D Program of China,No.2022YFC2010102Natural Science Foundation of Hunan Province,No.2021JC0003+1 种基金National Natural Science Foundation of China,No.82070812the Sinocare Diabetes Foundation,No.LYF2022039.
文摘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.
基金supported in part by the National Natural Science Foundation of China(62273310)the Natural Science Foundation of Zhejiang Province of China(LY22F030006,LZ24F030009)
文摘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.
文摘Non-aqueous emulsions have a wide range of applications in cosmetics,drug-controlled release,and the preparation of functional nanoparticles.However,due to the weaker polarity of non-aqueous solvents,these emulsions often exhibit inferior stability compared to their aqueous counterparts.In this experiment,the properties of quaternary ammonium surfactants in glycerol were investigated through surface tension measurements,to further enhance the stability of n-decane/glycerol emulsions,hydrophilic nanoparticles SiO_(2) were modified in situ using double tailed quaternary ammonium surfactants Di-C_(12)DAB and Di-C_(16)DAB.Stable n-decane/glycerol Pickering emulsions were successfully prepared.These emulsions were stable at 45℃for over six months,and no significant changes in droplet size occurred.The minimum droplet size of the emulsion was only 2-3μm.Contact angle measurements showed that the wettability of the silica surface was tremendously affected by the concentration and the alkyl chain length of the double-tailed surfactants.In the presence of Di-C_(12)DAB,the contact angle of glycerol on the silica surface increased monotonically with the surfactant concentration.This explains the phenomenon that the Pickering emulsions containing Di-C_(12)DAB and silica particles were stable within the contact angle range of 80°-120°.Comparatively,the contact angle of the glycerol on the silica surface in the presence of Di-C_(16)DAB first increased with surfactant concentrations and then decreased,reaching a maximum at 0.6 mmol/L.It can be concluded that Di-C_(12)DAB formed monolayers at the surface of silica particles within all investigated concentrations.On the contrary,Di-C_(16)DAB formed monolayers at concentrations below 0.6 mmol/L and formed double layers at concentrations above 0.6 mmol/L,leading to a non-monotonic change in the contact angle with respect to concentration.Using these stable non-aqueous Pickering emulsions as templates,polymer microspheres with a particle size of 2-3μm were successfully prepared with high yield.This work is helpful to expand the potential applications of non-aqueous emulsions in the encapsulation of drug,controlled release,material preparation,and cosmetic formulations.
文摘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.
基金financially supported by the National Natural Science Foundation of China(No.22131008)。
文摘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.
文摘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.
基金financially supported by the Beijing Natural Science Foundation,China(Nos.2254087 and 2242008)the Beijing Information Science and Technology University Foundation,China(No.1925008)Beijing Information Science and Technology University Young Faculty Support Program,China(No.YBT202411).
文摘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.
文摘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.
基金supported by the Project of State Key Laboratory of Treatments and Recycling for Organic Effluents by the Adsorption in Petroleum and Chemical Industry,Soochow University(No.SDHY2207)the Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes,Ministry of Education,College of Environment,Hohai University(No.B230203006)A Project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘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.
文摘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.
基金Project supported by the National Natural Science Foundation of China(22279025,21773048,52302119)the Fundamental Research Funds for the Central Universities(2023FRFK06005,HIT.NSRIF202204)。
文摘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.
基金funded by the National Key Research and Development Program of China(2022YFB2404500)the Shenzhen Outstanding Talents Training Fund(01090100002)the National Natural Science Foundation of China(52201280)。
文摘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.
