The sandy conglomerate reservoir is tight and exhibits strong heterogeneity,rendering conventional water flooding and gas drive methods inefficient and challenging for the effective development.CO_(2) water alternatin...The sandy conglomerate reservoir is tight and exhibits strong heterogeneity,rendering conventional water flooding and gas drive methods inefficient and challenging for the effective development.CO_(2) water alternating gas(CO_(2)-WAG)injection as an effective enhanced oil recovery(EOR)method has been applied in heterogeneous reservoirs.Simultaneously,it facilitates carbon sequestration,contributing to the green and low-carbon transformation of energy.However,the EOR mechanisms and influencing factors are still unclear for the development of heterogeneous sandy conglomerate reservoirs.In this paper,we conducted core flooding experiments combined nuclear magnetic resonance(NMR)technology to investigate EOR mechanisms of the CO_(2)-WAG injection on the multiscale(reservoir,layer,and pore).The study compared multiscale oil recovery in sandy conglomerate reservoirs under both miscible and immiscible conditions,while also analyzing the effects of water-gas ratio and injection rate.In the immiscible state,the CO_(2)-WAG displacement achieves an oil recovery of approximately 22.95%,representing a 7.82%increase compared to CO_(2) flooding.This method effectively inhibits CO_(2) breakthrough in high-permeability layers while enhancing the oil recovery in medium-and low-permeability layers.Furthermore,CO_(2)-WAG displacement improves the microscopic oil displacement efficiency within mesopores and micropores.As the water-gas ratio increases,the total oil recovery rises,with enhanced oil recovery in low-permeability layers and micropores.Moreover,a gradual increase in injection rate leads to a decrease in total oil recovery,but it leads to an increase in oil recovery from low-permeability sandy conglomerate layers and micropores.In the miscible state,the displacement efficiency of CO_(2)-WAG is significantly enhanced,the total oil recovery three times higher than that in the immiscible state.In particular,the oil recovery from low permeability layers and micropores has further improved.Additionally,experimental results indicate that parameters such as water-gas ratio and injection rate do not significantly affect the oil recovery of CO_(2)-WAG miscible displacement.Therefore,maintaining the reservoir pressure above the minimum miscible pressure is the key to maximizing ultimate recovery factor in these reservoirs.展开更多
Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal str...Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.展开更多
In dynamic 5G network environments,user mobility and heterogeneous network topologies pose dual challenges to the effort of improving performance of mobile edge caching.Existing studies often overlook the dynamic natu...In dynamic 5G network environments,user mobility and heterogeneous network topologies pose dual challenges to the effort of improving performance of mobile edge caching.Existing studies often overlook the dynamic nature of user locations and the potential of device-to-device(D2D)cooperative caching,limiting the reduction of transmission latency.To address this issue,this paper proposes a joint optimization scheme for edge caching that integrates user mobility prediction with deep reinforcement learning.First,a Transformer-based geolocation prediction model is designed,leveraging multi-head attention mechanisms to capture correlations in historical user trajectories for accurate future location prediction.Then,within a three-tier heterogeneous network,we formulate a latency minimization problem under a D2D cooperative caching architecture and develop a mobility-aware Deep Q-Network(DQN)caching strategy.This strategy takes predicted location information as state input and dynamically adjusts the content distribution across small base stations(SBSs)andmobile users(MUs)to reduce end-to-end delay inmulti-hop content retrieval.Simulation results show that the proposed DQN-based method outperforms other baseline strategies across variousmetrics,achieving a 17.2%reduction in transmission delay compared to DQNmethods withoutmobility integration,thus validating the effectiveness of the joint optimization of location prediction and caching decisions.展开更多
In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(...In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(−)][DBUH^(+)],a series of novel heterogeneous dual-ionic poly(ionic liquid)s(PILs)were synthesized readily from 2-(dimethylamino)ethyl methacrylate(DMAEMA),bromo-substituted aliphatic acids,organic bases and divinylbenzene(DVB).The structures,compositions and morphologies were characterized or determined by nuclear magnetic resonance(NMR),thermal gravimetric analysis(TGA),infrared spectroscopy(IR),scanning electron microscopes(SEM),and Brunauer-Emmett-Teller analysis(BET),etc.Application of the P[D+COO^(−)][Br^(−)][DBUH^(+)]series as catalysts in converting CO_(2)into cyclic carbonates showed that P[D+COO^(−)][Br^(−)][DBUH^(+)]-2/1/0.6was able to catalyze epiclorohydrin-CO_(2)cycloaddition the most efficiently.This afforded chloropropylene carbonate(CPC)in 98.4%yield with≥99%selectivity in 24 hr under solvent-and additive-free conditions at atmospheric pressure.Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance.In addition,it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields.Finally,key catalytic active sites were probed,and a reasonable mechanism was proposed accordingly.In summary,this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides amild and environmentally benign approach to the fixation and utilization of carbon dioxide.展开更多
Silicon(Si)is an inevitable impurity element in the AZ31 alloy.In this study,the Si impurity was detected mainly as fine Mg_(2)Si particles dispersed widely within the central region of the Mg_(17)Al_(12) phase.During...Silicon(Si)is an inevitable impurity element in the AZ31 alloy.In this study,the Si impurity was detected mainly as fine Mg_(2)Si particles dispersed widely within the central region of the Mg_(17)Al_(12) phase.During the solidification process,the Mg_(2)Si particle precipitates at about 565℃,before the Mg_(17)Al_(12) phase of 186℃,potentially acting as the heterogeneous nucleation core for the Mg_(17)Al_(12) phase.The orientation relationship between Mg_(2)Si and Mg_(17)Al_(12) was investigated using the Edge-to-Edge matching model(E2EM)calculations,which showed a misfit of only 0.1%.This low misfit suggests that Mg_(2)Si can serve as a heterogeneous nucleation site for Mg_(17)Al_(12).The surface and interface structures of Mg_(2)Si(220)and Mg_(17)Al_(12)(332)were constructed,and then investigated through the first-principles calculation.The theoretical results indicate that Mg and Al are easily adsorbed on the surface of Mg_(2)Si,with Al showing higher adsorption energy than Mg.Furthermore,the interface between Mg_(2)Si and Mg_(17)Al_(12) exhibits favorable thermodynamic stability.Combined with experiments and theoretical calculations,it is confirmed that the Mg_(2)Si particles,formed due to the Si impurity,provide effective heterogeneous nucleation sites for the Mg_(17)Al_(12) phase.展开更多
The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development ...The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.展开更多
separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed b...separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.展开更多
TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselec...TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselectivities.The catalyst was easily separated from the reaction mixture and was recycled four times with no significant loss of its catalytic activity.展开更多
An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogen...An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.展开更多
The catalytic conversion of CO_(2) to fuels or chemicals is considered to be an effective pathway to mitigate the greenhouse effect. To develop new types of efficient and durable catalysts, it is critical to identify ...The catalytic conversion of CO_(2) to fuels or chemicals is considered to be an effective pathway to mitigate the greenhouse effect. To develop new types of efficient and durable catalysts, it is critical to identify the catalytic active sites, surface intermediates, and reaction mechanisms to reveal the relationship between the active sites and catalytic performance. However, the structure of a heterogeneous catalyst usually dynamically changes during reaction, bringing a great challenge for the identification of catalytic active sites and reaction pathways. Therefore, in-situ/operando techniques have been employed to real-time monitor the dynamic evolution of the structure of active sites under actual reaction conditions to precisely build the structure–function relationship. Here, we review the recent progress in the application of various in-situ/operando techniques in identifying active sites for catalytic conversion of CO_(2) over heterogeneous catalysts. We systematically summarize the applications of various optical and X-ray spectroscopy techniques, including Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), in identifying active sites and determining reaction mechanisms of the CO_(2) thermochemical conversion with hydrogen and light alkanes over heterogeneous catalysts. Finally, we discuss challenges and opportunities for the development of in-situ characterization in the future to further enlarge the capability of these powerful techniques.展开更多
The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving c...The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.展开更多
Both activity and stability of the catalyst can be improved in heterogeneous Fenton reaction,in particular,with no limitation for the working p H and no production of the sludge.In this work,a combination of catalyst ...Both activity and stability of the catalyst can be improved in heterogeneous Fenton reaction,in particular,with no limitation for the working p H and no production of the sludge.In this work,a combination of catalyst Cu_2O and pore-channel-dispersed H_2O_2is proposed to treat the pulp wastewater.Degradation degree of CODs in the wastewater was up to 77%in the ceramic membrane reactor using Cu_2O powder(2.0 g·L^(-1))and membranefeeding H_2O_2(0.8 ml·L^(-1))within 60 min.Evolution of·OH radical formation in the advanced oxidation process was analyzed with a fluorescent method.Utilization efficiency of H_2O_2was successfully enhanced by 10%with the membrane distributor.Further on,the catalyst recyclability was evaluated in a five-cycle test.The concentration of copper ions being dissolved in the treated water was monitored with ICP.After Cu_2O/H_2O_2(membrane)treatment the effluent is qualified to discharge with COD concentration lower than 15 mg·L^(-1)with regard to the national standard GB25467-2010.展开更多
ZnFe2O4 nanoparticles （ZFNPs） were developed as catalyst for the degradation of benzotriazole （BTA） by heterogeneous photoelectro- Fenton （PE-Fenton） like process. ZFNPs were prepared by a co-precipitation proce...ZnFe2O4 nanoparticles （ZFNPs） were developed as catalyst for the degradation of benzotriazole （BTA） by heterogeneous photoelectro- Fenton （PE-Fenton） like process. ZFNPs were prepared by a co-precipitation process and then characterized with transmission electron microscopy （TEM）, X-ray fluorescence （XRF）, X-ray diffraction （XRD） and BET surface area. Using such ZFNPs as catalyst, the degradation of BTA was investigated. Due to the high catalytic activity of ZFNPs, PE-Fenton like process showed efficient degradation of BTA. The influencing factors such as pH, dosage of ZFNPs, applied potential and initial concentration of BTA were systematically investigated. Under the optimum conditions, 91.2% of BTA was removed after 180 rain treatment.展开更多
Series of heterogeneous interfacial engineered TiO2(C-TiO2) with controllable carbon content were facilely synthesized by incipient-wet impregnation using glucose and subsequent thermal carbonization. The obtained C-T...Series of heterogeneous interfacial engineered TiO2(C-TiO2) with controllable carbon content were facilely synthesized by incipient-wet impregnation using glucose and subsequent thermal carbonization. The obtained C-TiO2 were used as catalytic supports to load Pd nanoparticles for H2 O2 direct synthesis from H2 and O2. The as-prepared samples were systematically studied by transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), air isothermal microcalorimeter, temperature-programmed reduction of H2(H2-TPR), and so on. The catalytic results showed that H2 O2 productivity and H2O2 selectivity of Pd/C-TiO2 firstly rose with increasing carbon content and then declined. Pd/C-TiO2 catalyst with 1.89 wt% of carbon content showed the best catalytic performance that had 61.2% of selectivity and 2192 mmol H2O2/g Pd/h of productivity, which were significantly better than those of pristine Pd/TiO2(45.2% and 1827 mmol H2O2/g Pd/h). Various characterization results displayed that the carbon species were heterogeneously dispersed on TiO2 surface. Moreover, no obvious geometric transformation in supports and Pd nanoparticles were observed among different catalysts. The superficial hydrophobicity of Pd/C-TiO2 was gradually promoted with increasing carbon content, which led to the corresponding decrease in adsorption energy of H2O2 with catalysts. According to structure-performance relationship analyses, the heterogeneous interfacial engineering of carbon could maintain the interaction of Pd nanoparticles with TiO2 and simultaneously accelerate the H2O2 desorption. Both factors further determined the excellent H2O2 direct synthesis performance of Pd/C-TiO2.展开更多
Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have o...Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have obtained a novel heterogeneous lamellar Ti_(2)AlC/TiAl composite with superior strength-plasticity synergy,i.e.,compressive strength of∼2065 MPa and fracture strain of∼27%.A combination of micropil-lar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti_(2)AlC reinforcement,lamellar architecture and heteroge-neous interface.More specifically,multiple deformation modes in Ti_(2)AlC,i.e.,basal-plane dislocations,atomic-scale ripples and kink bands,could be activated during the compression,thus promoting the plas-tic deformation capability of composite.Meanwhile,the lamellar architecture could not only induce sig-nificant stress redistribution and crack deflection between Ti_(2)AlC and TiAl,but also generate high-density SFs and DTs interactions in TiAl,leading to an improved strength and strain hardening ability.In addi-tion,profuse unique Ti_(2)AlC(1¯10¯3)/TiAl(111)interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mecha-nisms.These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.展开更多
The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be class...The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）, the heterogeneous reaction mechanism of NO2 on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO2 on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.展开更多
In this paper,a new communication model is built named grouping D2D(GD2D).Different from the traditional D2D coordination,we proposed GD2D communication in licensed and unlicensed spectrum simultaneously.We formulate ...In this paper,a new communication model is built named grouping D2D(GD2D).Different from the traditional D2D coordination,we proposed GD2D communication in licensed and unlicensed spectrum simultaneously.We formulate a resource allocation problem,which aims at maximizing the energy efficiency(EE)of the system while guaranteeing the quality-of-service(Qos)of users.To efficiently solve this problem,the non-convex optimization problem is first transformed into a convex optimization problem.By transforming the fractional-form problem into an equivalent subtractive-form problem,an iterative power allocation algorithm is proposed to maximize the system EE.Moreover,the optimal closedform power allocation expressions are derived by the Lagrangian approach.Simulation results show that our algorithm achieves higher EE performance than the traditional D2D communication scheme.展开更多
In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designe...In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designed for massive number of machine-typecommunications(MTC) user equipments'(UEs) transmissions. A user association problem for UEs' energy efficiency maximization is formulated considering the HTC UEs' quality of service(QoS) guarantees and load balance among multiple BSs, simultaneously. A distributed iterative algorithm is developed to solve the optimization problem. In addition, the convergence of the proposed algorithm is proved. Simulation results show that our proposed scheme outperforms other schemes in terms of energy efficiency and QoS guarantees.展开更多
A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported. All types of aldehydes, incl...A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported. All types of aldehydes, including aromatic, unsaturated, and heterocyclic, are used. The silica gel/sulfonic acid catalyst （SiO2-R-SO3H） is completely heterogeneous and can be recycled.展开更多
Nano titania-supported sulfonic acid（n-TSA） has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2,4,6-triarylpyridines through one-pot three-c...Nano titania-supported sulfonic acid（n-TSA） has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2,4,6-triarylpyridines through one-pot three-component reaction of acetophenones, aryl aldehydes and ammonium acetate. This reported method illustrates several advantages such as environmental friendliness reaction conditions,simplicity, short reaction time, easy work up, reusability of catalyst and high yields of the products. One new compound is reported too. Furthermore, the catalyst could be recycled after a simple work-up, and reused at least six times without substantial reduction in its catalytic activity.展开更多
基金supported by the National Natural Science Foundation of China(No.52204065,No.52374063)the Independent Innovation Research Project of China University of Petroleum(No.24CX06017A)Shandong Provincial Natural Science Foundation,China(No.ZR2024QE075,No.ZR2023ME049)。
文摘The sandy conglomerate reservoir is tight and exhibits strong heterogeneity,rendering conventional water flooding and gas drive methods inefficient and challenging for the effective development.CO_(2) water alternating gas(CO_(2)-WAG)injection as an effective enhanced oil recovery(EOR)method has been applied in heterogeneous reservoirs.Simultaneously,it facilitates carbon sequestration,contributing to the green and low-carbon transformation of energy.However,the EOR mechanisms and influencing factors are still unclear for the development of heterogeneous sandy conglomerate reservoirs.In this paper,we conducted core flooding experiments combined nuclear magnetic resonance(NMR)technology to investigate EOR mechanisms of the CO_(2)-WAG injection on the multiscale(reservoir,layer,and pore).The study compared multiscale oil recovery in sandy conglomerate reservoirs under both miscible and immiscible conditions,while also analyzing the effects of water-gas ratio and injection rate.In the immiscible state,the CO_(2)-WAG displacement achieves an oil recovery of approximately 22.95%,representing a 7.82%increase compared to CO_(2) flooding.This method effectively inhibits CO_(2) breakthrough in high-permeability layers while enhancing the oil recovery in medium-and low-permeability layers.Furthermore,CO_(2)-WAG displacement improves the microscopic oil displacement efficiency within mesopores and micropores.As the water-gas ratio increases,the total oil recovery rises,with enhanced oil recovery in low-permeability layers and micropores.Moreover,a gradual increase in injection rate leads to a decrease in total oil recovery,but it leads to an increase in oil recovery from low-permeability sandy conglomerate layers and micropores.In the miscible state,the displacement efficiency of CO_(2)-WAG is significantly enhanced,the total oil recovery three times higher than that in the immiscible state.In particular,the oil recovery from low permeability layers and micropores has further improved.Additionally,experimental results indicate that parameters such as water-gas ratio and injection rate do not significantly affect the oil recovery of CO_(2)-WAG miscible displacement.Therefore,maintaining the reservoir pressure above the minimum miscible pressure is the key to maximizing ultimate recovery factor in these reservoirs.
基金Project supported by the National Innovative Training Program for College Students of China(Grant No.2023069)the University Research and Innovation Project of the National University of Defense Technology。
文摘Silicon nitride photonics has emerged as a promising integrated optical platform due to its broad transparency window,low optical loss,and mature fabrication technology.However,the inherent centrosymmetric crystal structure of silicon nitride fundamentally restricts its applications in second-order nonlinear optical processes.Monolayer transition metal dichalcogenides,particularly tungsten disulfide(WS_(2)),exhibit strong second-order nonlinear responses,making them ideal candidates for nonlinear photonic applications.Herein,we demonstrate a heterogeneously integrated platform combining silicon nitride waveguides with chemical vapor deposition(CVD)-grown monolayer WS_(2),enabling second harmonic generation.A specially designed silica cladding featuring gentle-slope profile on silicon nitride strip waveguides facilitates the integration of centimeter-scale WS_(2)film with photonic circuits.This approach provides a robust solution for incorporating second-order nonlinearity into silicon nitride photonic systems.The demonstrated platform holds significant potential for advancing quantum networks,visible-light lasers,and integrated optical modulation/detection systems.
基金supported by the Liaoning Provincial Education Department Fund,grant number JYTZD2023083.
文摘In dynamic 5G network environments,user mobility and heterogeneous network topologies pose dual challenges to the effort of improving performance of mobile edge caching.Existing studies often overlook the dynamic nature of user locations and the potential of device-to-device(D2D)cooperative caching,limiting the reduction of transmission latency.To address this issue,this paper proposes a joint optimization scheme for edge caching that integrates user mobility prediction with deep reinforcement learning.First,a Transformer-based geolocation prediction model is designed,leveraging multi-head attention mechanisms to capture correlations in historical user trajectories for accurate future location prediction.Then,within a three-tier heterogeneous network,we formulate a latency minimization problem under a D2D cooperative caching architecture and develop a mobility-aware Deep Q-Network(DQN)caching strategy.This strategy takes predicted location information as state input and dynamically adjusts the content distribution across small base stations(SBSs)andmobile users(MUs)to reduce end-to-end delay inmulti-hop content retrieval.Simulation results show that the proposed DQN-based method outperforms other baseline strategies across variousmetrics,achieving a 17.2%reduction in transmission delay compared to DQNmethods withoutmobility integration,thus validating the effectiveness of the joint optimization of location prediction and caching decisions.
基金supported by the Applied Basic Research Foundation of Guangdong Province(No.2019A1515110551)the Science Foundation for Distinguished Scholars of Dongguan University of Technology(No.196100041051).
文摘In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(−)][DBUH^(+)],a series of novel heterogeneous dual-ionic poly(ionic liquid)s(PILs)were synthesized readily from 2-(dimethylamino)ethyl methacrylate(DMAEMA),bromo-substituted aliphatic acids,organic bases and divinylbenzene(DVB).The structures,compositions and morphologies were characterized or determined by nuclear magnetic resonance(NMR),thermal gravimetric analysis(TGA),infrared spectroscopy(IR),scanning electron microscopes(SEM),and Brunauer-Emmett-Teller analysis(BET),etc.Application of the P[D+COO^(−)][Br^(−)][DBUH^(+)]series as catalysts in converting CO_(2)into cyclic carbonates showed that P[D+COO^(−)][Br^(−)][DBUH^(+)]-2/1/0.6was able to catalyze epiclorohydrin-CO_(2)cycloaddition the most efficiently.This afforded chloropropylene carbonate(CPC)in 98.4%yield with≥99%selectivity in 24 hr under solvent-and additive-free conditions at atmospheric pressure.Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance.In addition,it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields.Finally,key catalytic active sites were probed,and a reasonable mechanism was proposed accordingly.In summary,this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides amild and environmentally benign approach to the fixation and utilization of carbon dioxide.
基金supported by the National Natural Science Foundation of China(Nos.51871100 and 12074126).
文摘Silicon(Si)is an inevitable impurity element in the AZ31 alloy.In this study,the Si impurity was detected mainly as fine Mg_(2)Si particles dispersed widely within the central region of the Mg_(17)Al_(12) phase.During the solidification process,the Mg_(2)Si particle precipitates at about 565℃,before the Mg_(17)Al_(12) phase of 186℃,potentially acting as the heterogeneous nucleation core for the Mg_(17)Al_(12) phase.The orientation relationship between Mg_(2)Si and Mg_(17)Al_(12) was investigated using the Edge-to-Edge matching model(E2EM)calculations,which showed a misfit of only 0.1%.This low misfit suggests that Mg_(2)Si can serve as a heterogeneous nucleation site for Mg_(17)Al_(12).The surface and interface structures of Mg_(2)Si(220)and Mg_(17)Al_(12)(332)were constructed,and then investigated through the first-principles calculation.The theoretical results indicate that Mg and Al are easily adsorbed on the surface of Mg_(2)Si,with Al showing higher adsorption energy than Mg.Furthermore,the interface between Mg_(2)Si and Mg_(17)Al_(12) exhibits favorable thermodynamic stability.Combined with experiments and theoretical calculations,it is confirmed that the Mg_(2)Si particles,formed due to the Si impurity,provide effective heterogeneous nucleation sites for the Mg_(17)Al_(12) phase.
基金financially supported by the National Natural Science Foundation of China(22205205)the Science Foundation of Zhejiang Sci-Tech University(ZSTU)under Grant No.21062337-Y。
文摘The electrochemical biomass valorization of industrial by-products or pollutants using renewable electricity offers significant promise for carbon neutrality.However,the huge challenges still exist in the development of efficient bifunctional electrocatalysts.Herein,we put forward a high-efficiency coelectrolysis system by coupling the nitrite reduction reaction(NO_(2)RR)and the glycerol oxidation reaction(GOR)over a novel heterogeneous β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl catalyst.Theβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl shows excellent bifunctional performance with high Faradaic efficiencies of formate(90.1%)and NH_(3)(91.9%)at cell voltage of 1.5 V,high yield rate of formate(89.6 mg h^(-1)cm^(-2))and NH_(3)(36.07 mg h^(-1)cm^(-2))at cell voltage of 1.9 V,and superior stability in an anion exchange membrane co-electrolyzer.The in-situ Raman result confirms the unique Co/Cu-based bimetallic synergistic sites of β-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl towards superior GOR performance,while the operando Fourier transform infrared spectroscopy demonstrates the improved protonation kinetics of key intermediates and optimized water dissociation ability ofβ-Co(OH)_(2)/Cu_(2)(OH)_(3)Cl for high NO_(2)RR activity.Our work illuminates alternative avenues to exploit the innovative and energy-saving technology for the co-production of high-added chemicals.
基金supported by the National Natural Science Foundation of China (21203017)Open Fund of State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (N-11-3)+1 种基金Program for Liaoning Excellent Talents in University (LNET)the Funda-mental Research Funds for the Central Universities (DC201502020304)~~
文摘separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.
文摘TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselectivities.The catalyst was easily separated from the reaction mixture and was recycled four times with no significant loss of its catalytic activity.
文摘An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.
基金Authors acknowledge the financial support from the National Natural Science Foundation of China(NSFC)under Grant No.21978148 and 21808120.
文摘The catalytic conversion of CO_(2) to fuels or chemicals is considered to be an effective pathway to mitigate the greenhouse effect. To develop new types of efficient and durable catalysts, it is critical to identify the catalytic active sites, surface intermediates, and reaction mechanisms to reveal the relationship between the active sites and catalytic performance. However, the structure of a heterogeneous catalyst usually dynamically changes during reaction, bringing a great challenge for the identification of catalytic active sites and reaction pathways. Therefore, in-situ/operando techniques have been employed to real-time monitor the dynamic evolution of the structure of active sites under actual reaction conditions to precisely build the structure–function relationship. Here, we review the recent progress in the application of various in-situ/operando techniques in identifying active sites for catalytic conversion of CO_(2) over heterogeneous catalysts. We systematically summarize the applications of various optical and X-ray spectroscopy techniques, including Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), in identifying active sites and determining reaction mechanisms of the CO_(2) thermochemical conversion with hydrogen and light alkanes over heterogeneous catalysts. Finally, we discuss challenges and opportunities for the development of in-situ characterization in the future to further enlarge the capability of these powerful techniques.
基金financial support from the King Abdullah University of Science and Technology(KAUST).
文摘The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.
基金Supported by the Prospective Research Project of Jiangsu Province(BY2014005-06)
文摘Both activity and stability of the catalyst can be improved in heterogeneous Fenton reaction,in particular,with no limitation for the working p H and no production of the sludge.In this work,a combination of catalyst Cu_2O and pore-channel-dispersed H_2O_2is proposed to treat the pulp wastewater.Degradation degree of CODs in the wastewater was up to 77%in the ceramic membrane reactor using Cu_2O powder(2.0 g·L^(-1))and membranefeeding H_2O_2(0.8 ml·L^(-1))within 60 min.Evolution of·OH radical formation in the advanced oxidation process was analyzed with a fluorescent method.Utilization efficiency of H_2O_2was successfully enhanced by 10%with the membrane distributor.Further on,the catalyst recyclability was evaluated in a five-cycle test.The concentration of copper ions being dissolved in the treated water was monitored with ICP.After Cu_2O/H_2O_2(membrane)treatment the effluent is qualified to discharge with COD concentration lower than 15 mg·L^(-1)with regard to the national standard GB25467-2010.
基金supported by the National Natural Science Foundation of China (No. 20977037)the Fundamental Research Funds for the Central Universities (No.2011TS062)
文摘ZnFe2O4 nanoparticles （ZFNPs） were developed as catalyst for the degradation of benzotriazole （BTA） by heterogeneous photoelectro- Fenton （PE-Fenton） like process. ZFNPs were prepared by a co-precipitation process and then characterized with transmission electron microscopy （TEM）, X-ray fluorescence （XRF）, X-ray diffraction （XRD） and BET surface area. Using such ZFNPs as catalyst, the degradation of BTA was investigated. Due to the high catalytic activity of ZFNPs, PE-Fenton like process showed efficient degradation of BTA. The influencing factors such as pH, dosage of ZFNPs, applied potential and initial concentration of BTA were systematically investigated. Under the optimum conditions, 91.2% of BTA was removed after 180 rain treatment.
基金supported by the National Natural Science Foundation of China(21878143,21476106,21838004)Joint Re-search Fund for Overseas Chinese Scholars and Scholars in Hong Kong and Macao Young Scholars(21729601)+1 种基金the fund of State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201702)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)~~
文摘Series of heterogeneous interfacial engineered TiO2(C-TiO2) with controllable carbon content were facilely synthesized by incipient-wet impregnation using glucose and subsequent thermal carbonization. The obtained C-TiO2 were used as catalytic supports to load Pd nanoparticles for H2 O2 direct synthesis from H2 and O2. The as-prepared samples were systematically studied by transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), air isothermal microcalorimeter, temperature-programmed reduction of H2(H2-TPR), and so on. The catalytic results showed that H2 O2 productivity and H2O2 selectivity of Pd/C-TiO2 firstly rose with increasing carbon content and then declined. Pd/C-TiO2 catalyst with 1.89 wt% of carbon content showed the best catalytic performance that had 61.2% of selectivity and 2192 mmol H2O2/g Pd/h of productivity, which were significantly better than those of pristine Pd/TiO2(45.2% and 1827 mmol H2O2/g Pd/h). Various characterization results displayed that the carbon species were heterogeneously dispersed on TiO2 surface. Moreover, no obvious geometric transformation in supports and Pd nanoparticles were observed among different catalysts. The superficial hydrophobicity of Pd/C-TiO2 was gradually promoted with increasing carbon content, which led to the corresponding decrease in adsorption energy of H2O2 with catalysts. According to structure-performance relationship analyses, the heterogeneous interfacial engineering of carbon could maintain the interaction of Pd nanoparticles with TiO2 and simultaneously accelerate the H2O2 desorption. Both factors further determined the excellent H2O2 direct synthesis performance of Pd/C-TiO2.
基金the National Natural Science Foundation of China(Grant No.52101174)the State Key Lab of Advanced Metals and Materials(No.2022-Z15).
文摘Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have obtained a novel heterogeneous lamellar Ti_(2)AlC/TiAl composite with superior strength-plasticity synergy,i.e.,compressive strength of∼2065 MPa and fracture strain of∼27%.A combination of micropil-lar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti_(2)AlC reinforcement,lamellar architecture and heteroge-neous interface.More specifically,multiple deformation modes in Ti_(2)AlC,i.e.,basal-plane dislocations,atomic-scale ripples and kink bands,could be activated during the compression,thus promoting the plas-tic deformation capability of composite.Meanwhile,the lamellar architecture could not only induce sig-nificant stress redistribution and crack deflection between Ti_(2)AlC and TiAl,but also generate high-density SFs and DTs interactions in TiAl,leading to an improved strength and strain hardening ability.In addi-tion,profuse unique Ti_(2)AlC(1¯10¯3)/TiAl(111)interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mecha-nisms.These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.
基金supported by the National Natural Science Foundation of China (No. 41005071,40490265,20637020)the National Basic Research Program of China(No. 2002CB410802 )the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 09K01ESPCP)
文摘The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）, the heterogeneous reaction mechanism of NO2 on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO2 on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.
基金supported in part by the National Natural Science Foundation of China under Grant no.61473066 and Grant no.61601109in part by the Fundamental Research Funds for the Central Universities under Grant No.N152305001.
文摘In this paper,a new communication model is built named grouping D2D(GD2D).Different from the traditional D2D coordination,we proposed GD2D communication in licensed and unlicensed spectrum simultaneously.We formulate a resource allocation problem,which aims at maximizing the energy efficiency(EE)of the system while guaranteeing the quality-of-service(Qos)of users.To efficiently solve this problem,the non-convex optimization problem is first transformed into a convex optimization problem.By transforming the fractional-form problem into an equivalent subtractive-form problem,an iterative power allocation algorithm is proposed to maximize the system EE.Moreover,the optimal closedform power allocation expressions are derived by the Lagrangian approach.Simulation results show that our algorithm achieves higher EE performance than the traditional D2D communication scheme.
基金supported by Major Research Plan of National Natural Science Foundation of China(No.91438115)National Natural Science Foundation of China(No.61371123,No.61301165)+2 种基金Jiangsu Province Natural Science Foundation(BK2012055)China Postdoctoral Science Foundation(2014M552612)Jiangsu Postdoctoral Science Foundation(No.1401178C)
文摘In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designed for massive number of machine-typecommunications(MTC) user equipments'(UEs) transmissions. A user association problem for UEs' energy efficiency maximization is formulated considering the HTC UEs' quality of service(QoS) guarantees and load balance among multiple BSs, simultaneously. A distributed iterative algorithm is developed to solve the optimization problem. In addition, the convergence of the proposed algorithm is proved. Simulation results show that our proposed scheme outperforms other schemes in terms of energy efficiency and QoS guarantees.
文摘A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported. All types of aldehydes, including aromatic, unsaturated, and heterocyclic, are used. The silica gel/sulfonic acid catalyst （SiO2-R-SO3H） is completely heterogeneous and can be recycled.
基金the Faculty of Chemistry of Semnan University for supporting this work
文摘Nano titania-supported sulfonic acid（n-TSA） has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2,4,6-triarylpyridines through one-pot three-component reaction of acetophenones, aryl aldehydes and ammonium acetate. This reported method illustrates several advantages such as environmental friendliness reaction conditions,simplicity, short reaction time, easy work up, reusability of catalyst and high yields of the products. One new compound is reported too. Furthermore, the catalyst could be recycled after a simple work-up, and reused at least six times without substantial reduction in its catalytic activity.
