ing electrons from BPA molecules,the N-CNTs/PDS system effectively minimised oxidant wastage and mitigated the risk of secondary pollution,ensuring efficient utilisation of active sites on N-CNTs and sustaining a high...ing electrons from BPA molecules,the N-CNTs/PDS system effectively minimised oxidant wastage and mitigated the risk of secondary pollution,ensuring efficient utilisation of active sites on N-CNTs and sustaining a high catalytic rate.The formation of the N-CNTs-PDS*complex significantly enhanced BPA degradation and mineralisation,thereby optimising PDS consumption.These findings highlight the unparalleled advantages of the N-CNTs/PDS system in managing complex wastewater,offering a promising and innovative solution for treating complex industrial wastewater and advancing environmental remediation efforts.展开更多
A reactive Tb（III） complex with 2-aminobenzoic acid（2-ABAH） and acrylonitrile（AN） as ligands was synthesized.The structure of the complex was characterized by elemental analysis and Fourier transform infrared sp...A reactive Tb（III） complex with 2-aminobenzoic acid（2-ABAH） and acrylonitrile（AN） as ligands was synthesized.The structure of the complex was characterized by elemental analysis and Fourier transform infrared spectrometry（FT-IR）.The results indicated that the ligands were coordinated with Tb（III） ion.Thermal gravity-derivative thermogravimetric（TG-DTG） analysis indicated that the complex kept stable up to 198 oC.Luminescence properties were investigated by UV-vis absorption spectra and fluorescence spectra.The results suggested that being excited at 361 nm,the complex exhibited characteristic emission of Tb（III） ion,revealing that the complex could be excited by 365 nm ultraviolet chip.The HOMO and LUMO,ΔE（HOMO-LUMO）,molecular frontier orbital,and the singlet state and triplet energy state levels of the ligands were calculated at the B3LYP/6-31＋G（d） level.The results indicated that intramolecular energy transfer mechanism followed Dexter exchange energy transfer theory.Both the calculation for excited state of ligand and energy transfer mechanism could provide the theoretical basis for the design of high luminescent materials of rare earth complexes with organic ligands.展开更多
Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in ...Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.展开更多
Long lasting blue-green-emitting Sr4Al14O25:Eu2+ phosphors were synthesized by solid-state reactions.The phosphors were investigated by X-ray diffraction(XRD) and fluorescence spectrophotometer.A pure phase of Sr4Al14...Long lasting blue-green-emitting Sr4Al14O25:Eu2+ phosphors were synthesized by solid-state reactions.The phosphors were investigated by X-ray diffraction(XRD) and fluorescence spectrophotometer.A pure phase of Sr4Al14O25:Eu2+ phosphor was obtained at 1250 °C.There are two different types of Eu emission centers in Sr4Al14O25:Eu2+ phosphor.The effects of the Eu2+ concentration and the reducing temperature on the distribution of Eu2+ among different sites were investigated.The energy transfer mechanism between...展开更多
Mass transfer performance of gas–liquid two-phase flow at microscale is the basis of application of microreactor in gas–liquid reaction systems.At present,few researches on the mass transfer property of annular flow...Mass transfer performance of gas–liquid two-phase flow at microscale is the basis of application of microreactor in gas–liquid reaction systems.At present,few researches on the mass transfer property of annular flow have been reported.Therefore,the mass transfer mechanism and relationship of gas–liquid annular flow in a microfluidic cross-junction device are studied in the present study.We find that the main factors,i.e.,flow pattern,liquid film thickness,liquid hydraulic retention time,phase interface fluctuation,and gas flow vorticity,which influence the flow mass transfer property,are directly affected both by gas and liquid flow velocities.But the influences of gas and liquid velocities on different mass transfer influencing factors are different.Thereout,the fitting relationships between gas and liquid flow velocities and mass transfer influencing factors are established.By comparing the results from calculations using fitting equations and simulations,it shows that the fitting equations have relatively high degrees of accuracy.Finally,the Pareto front,namely the Pareto optimal solution set,of gas and liquid velocity conditions for the best flow mass transfer property is obtained using the method of multi-objective particle swarm optimization.It is proved that the mass transfer property of the gas–liquid two-phase flow can be obviously enhanced under the guidance of the obtained Pareto optimal solution set through experimental verification.展开更多
Prestressed high-strength-concrete (PHC) tube-shaped pile is one of the recently used foundations for soft soil. The research on uplift resistance of PHC pile is helpful to the design of pile foundations. A field-scal...Prestressed high-strength-concrete (PHC) tube-shaped pile is one of the recently used foundations for soft soil. The research on uplift resistance of PHC pile is helpful to the design of pile foundations. A field-scale test program was conducted to study the uplift behavior and load transfer mechanism of PHC piles in soft soil. The pullout load tests were divided into two groups with different diameters, and there were three piles in each group. A detailed discussion of the axial load transfer and pile skin resistance distribution was also included. It is found from the tests that the uplift capacity increases with increasing the diameter of pile. When the diameter of piles increases from 500 to 600 mm, the uplift load is increased by 51.2%. According to the load-displacement (Q-S) curves, all the piles do not reach the ultimate state at the maximum load. The experimental results show that the piles still have uplift bearing capacity.展开更多
The mass and heat transfer mechanisms during radio frequency/vacuum （RF/V） drying of square-edged timber were analyzed and discussed in detail, and a new one-dimensional mathematical model to describe the transport ...The mass and heat transfer mechanisms during radio frequency/vacuum （RF/V） drying of square-edged timber were analyzed and discussed in detail, and a new one-dimensional mathematical model to describe the transport phenomena of mass and heat during continuous RF/V drying was derived from conservation equations based on the mass and heat transfer theory of porous materials The new model provided a relatively fast and efficient way to simulate vacuum drying behavior assisted by dielectric heating. Its advantages compared with the conventional models include： （1） Each independent vari- able has a separate control equation and is solved inde- pendently by converting the partial differential equation into a difference equation with the finite volume method; （2） The calculated data from different parts of the specimen can be displayed in the evolution curves, and the change law of the,parameters can be better described. After analyzing the calculated results, most of the important phenomena observed during RF/V drying were adequately described by this model.展开更多
The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forreco...The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene（solvent）,Span-80（surfactant）and di-（2-ethylhexyl） phosphoricacid（HDEHP,carrier）.The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu（NO3）3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.展开更多
The advanced oxidation system based on peracetic acid(PAA)has been proved to be a green and safe oxidation decontamination technology.Among them,the key challenge and complexity in current research lies in the directi...The advanced oxidation system based on peracetic acid(PAA)has been proved to be a green and safe oxidation decontamination technology.Among them,the key challenge and complexity in current research lies in the directional induction of PAA and its utilization for selective removal of refractory pollutants.This study prepared nitrogen-doped biochar(NBC)using compound pharmaceutical residues commonly found in traditional Chinese medicine as a precursor.A system based on NBC-activated PAA was constructed for sulfamethoxazole(SMX)degradation.The introduction of nitrogen significantly enhanced the degree of graphitization in NBC.The degradation system achieved 87.89%SMX degradation efficiency within 60 min.Furthermore,the formation of the intricate NBC-PAA*complex detected by in-situ Raman was of paramount importance as it facilitates enhanced electron transfer processes within the complex,thereby promoting PAA decomposition through electron loss.The formation of a new complex between SMX and NBC-PAA*facilitated the completion of electron transfer process within the complex.In summary,this study explored a novel approach for treating and disposing of solid waste from Chinese medicine residue by successfully inducing non-free radical degradation pathway using PAA system.It offers fresh insights and ideas in the fields of water treatment and solid waste management.展开更多
Electrochemical nitrate reduction(NO_(3)RR)offers a promising avenue for treating nitrate-contaminated water and recovering ammonia(NH_(3)),yet the complexities of direct electron transfer(DET)and hydrogen atom transf...Electrochemical nitrate reduction(NO_(3)RR)offers a promising avenue for treating nitrate-contaminated water and recovering ammonia(NH_(3)),yet the complexities of direct electron transfer(DET)and hydrogen atom transfer(HAT)mechanisms crucial for efficiency remain elusive.This study bridges the gap with a combined experimental and theoretical approach,elucidating the impact of catalyst structure on NO3RR pathways.We discover that catalysts favoring strong NO_(3^(-))adsorption and efficient water dissociation were more inclined towards DET,enhancing denitrification.The Fe@Fe_(3)O_(4)/FF cathode,leveraging the synergistic interplay between metallic Fe and Fe_(3)O_(4),excelled in NO3RR via DET,achieving an NH3yield of 0.28 mmol h-1cm-2and a Faradaic efficiency of 95.7%for NH3at-1.6 V(vs.SCE),with minimal nitrite accumulation at 100 mmol/L nitrate.Conversely,the Fe/FF and Fe_(3)O_(4)/CC cathodes showed reduced NH3production and increased nitrite levels,attributed to the lack of Fe_(3)O_(4)and metallic Fe,respectively,resulting in a dominant HAT mechanism.Moreover,Fe@Fe_(3)O_(4)/FF facilitated complete denitrification in real wastewater treatment by harnessing Cl^(-)for electrochemically mediated breakpoint chlorination.This research not only deepens our understanding of NO3RR mechanisms but also paves the way for designing superior nitrate reduction catalysts.展开更多
Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ do...Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3＋ and Tm3＋Ho3＋） ion is proposed. Codoping of Tm3＋ or Ho3＋ significantly reduces the lifetime of the Era＋： 4I13/2 level due to the energy transfer of Er3＋：4I13/2 →Tm3＋：3F4 or Er3＋：4I13/2 →Ho3＋： 5I7. Thus, the 2.7μm emission is strengthened and the 1,5μm emission is decreased accordingly especially in the Era＋/Tma＋ sample. The upconversion effects between the Er3＋/Tm3＋ and Er3＋/Ho3＋ doped ZBYA glasses are different attribute to the different energy transfer efficiencies. Both of the two codoped samples possess nearly equal large emission cross section （16.6 × 10 -21 cm-2） around 2.7 μm. The results indicate that this Er3＋/Tm3＋ or Er3＋/Ho3＋ doped ZBYA glass has potential applications in 2.7 μm laser.展开更多
The equilibrium and kinetic characteristics of the adsorption of erythromycin to Sepabeads SP825 were determined.The equilibrium data in a batch system was well described by a Langmuir isotherm.The separation performa...The equilibrium and kinetic characteristics of the adsorption of erythromycin to Sepabeads SP825 were determined.The equilibrium data in a batch system was well described by a Langmuir isotherm.The separation performance was investigated in a fixed-bed system with respect to the adsorption superficial velocity,ionic strength and pH.A mathematical model was used to simulate the mass transfer mechanism,taking film mass transfer,pore diffusion and axial dispersion into account.The model predictions were consistent with the experi-mental data and were consequently used to determine the mass transfer coefficients.展开更多
A novel inverted advanced treatment process of ozone/hydrogen peroxide(O_(3)/H_(2)O_(2))and biological activated carbon fluidized bed(BACFB)before the conventional process has been developed to treat the high-algae-la...A novel inverted advanced treatment process of ozone/hydrogen peroxide(O_(3)/H_(2)O_(2))and biological activated carbon fluidized bed(BACFB)before the conventional process has been developed to treat the high-algae-laden reservoir water,which aims to enhance the removal of dissolved organic matter(DOM),odorants as well as the precursors of disinfection by-products(DBPs).Before and after the renovation,the average value of chemical oxygen demand(determined by potassium permanganate method)in the filter effluent decreased from 2.18 to 1.15 mg/L.Likewise,the average concentrations of turbidity dropped from 0.640 to 0.098 NTU,indicating substantial improvement following the renovation.Formation potential of DBPs such as trihalomethanes and haloacetic acids were also reduced greatly.The results of the polarity rapid analysis method indicated that ozonation primarily removed non-polar and positively charged organic matter,while coagulation-sedimentation targeted non-positive organic matter.The results of fluorescence spectroscopy and highresolution mass spectrometry indicated that the new process effectively removed DOM,and decreased the number of nitrogen-containing compounds.Additionally,the inverted O_(3)/H_(2)O_(2) and BACFB process promoted the dynamic transformation between DOM components and significantly reduced overall aromatic content.This study provided a promising solution for treating high-algae-laden source water and verified the feasibility and effectiveness of this novel process in practice.展开更多
The phase transfer mechanism of 18-molybdophosphate anion at the water/nitrobenzene interfaca has been investigated by chronopotentiometry with cyclic linear current-scanning (CLC) and cyclic voltammetry (CV). The tra...The phase transfer mechanism of 18-molybdophosphate anion at the water/nitrobenzene interfaca has been investigated by chronopotentiometry with cyclic linear current-scanning (CLC) and cyclic voltammetry (CV). The transfer species is 18-molybdophosphtae anion with a charge number of-4, H_2[P_2Mo_(18)O_(62)]^(4-). The transfer process is controlled by diffusion at a slow polarization rate and considerably influenced by pH of the aqueous phase. The stable forms and pH range of the heteropoly anion in the aqueous solution can be directly confirmed through voltammetric behavior. The theoretical analysis of the relationship between the transfer potential and solution pH is identical to the experimental results. The linear concentration relationship with the transfer peak current is suggested to be used in the determination of heteropoly acids(salts).展开更多
The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional....The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional. The complex is connected through two different types of inter-molecular hydrogen bonds. After photo-excitation, both hydrogen bonds get strengthened, which can facilitate the ESDPT reaction. The scanned potential energy curve along the proton transfer coordinate indicates that the ESDPT reaction proceeds in a stepwise pattern.展开更多
Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy ...Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.展开更多
Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state dens...Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.展开更多
In order to clarify the mechanism and main influencing factors of the vibration energy coupling transmission with a dual-piston structure,a thermodynamic and dynamic coupling model of the free piston linear generator(...In order to clarify the mechanism and main influencing factors of the vibration energy coupling transmission with a dual-piston structure,a thermodynamic and dynamic coupling model of the free piston linear generator(FPLG)was established.The system energy conversion,vibration energy coupling transmission,and influencing factors were studied in detail.The coupling transmission paths and the secondary influence mechanism from in-cylinder combustion on vibration energy transmission were obtained.In addition,the influence of the movement characteristics of the dual-piston on the vibration energy transmission was studied,and the typical parameter variation law was obtained,which provides theoretical guidance for the subsequent vibration reduction design of the FPLG.展开更多
Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the con...Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the conditions of [TU]/[PPAO]<0.5 molar ratio isThe molecular weights of the polymers were found to be inversely proportional to 3/2-power of nitric acid concentration and 1-power of thiourea concentration. In addition, it is independent with the concentrations of monomer and PPAO, and decreases with increasing temperature.On the basis of these experimental results, a coordination-proton transfer mechanism for the initiation was proposed and discussed.展开更多
基金supported by the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Grant No.2024LHMS05048).
文摘ing electrons from BPA molecules,the N-CNTs/PDS system effectively minimised oxidant wastage and mitigated the risk of secondary pollution,ensuring efficient utilisation of active sites on N-CNTs and sustaining a high catalytic rate.The formation of the N-CNTs-PDS*complex significantly enhanced BPA degradation and mineralisation,thereby optimising PDS consumption.These findings highlight the unparalleled advantages of the N-CNTs/PDS system in managing complex wastewater,offering a promising and innovative solution for treating complex industrial wastewater and advancing environmental remediation efforts.
基金Project supported by the Program for Changjiang Scholar and Innovative Research Team in University (IRT0972)the International Cooperation Program of Shanxi Province (2009081046)the Postgraduate Innovation Program of Shanxi Province (20103023)
文摘A reactive Tb（III） complex with 2-aminobenzoic acid（2-ABAH） and acrylonitrile（AN） as ligands was synthesized.The structure of the complex was characterized by elemental analysis and Fourier transform infrared spectrometry（FT-IR）.The results indicated that the ligands were coordinated with Tb（III） ion.Thermal gravity-derivative thermogravimetric（TG-DTG） analysis indicated that the complex kept stable up to 198 oC.Luminescence properties were investigated by UV-vis absorption spectra and fluorescence spectra.The results suggested that being excited at 361 nm,the complex exhibited characteristic emission of Tb（III） ion,revealing that the complex could be excited by 365 nm ultraviolet chip.The HOMO and LUMO,ΔE（HOMO-LUMO）,molecular frontier orbital,and the singlet state and triplet energy state levels of the ligands were calculated at the B3LYP/6-31＋G（d） level.The results indicated that intramolecular energy transfer mechanism followed Dexter exchange energy transfer theory.Both the calculation for excited state of ligand and energy transfer mechanism could provide the theoretical basis for the design of high luminescent materials of rare earth complexes with organic ligands.
基金supported by National Key R&D Program of China (Grant No. 2017YFC1501100)the National Natural Science Foundation of China (Grant No. 51279090)Sponsored by Research Fund for Excellent Dissertation of China Three Gorges University
文摘Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.
基金supported by the National Natural Science Foundation of China (60477034)
文摘Long lasting blue-green-emitting Sr4Al14O25:Eu2+ phosphors were synthesized by solid-state reactions.The phosphors were investigated by X-ray diffraction(XRD) and fluorescence spectrophotometer.A pure phase of Sr4Al14O25:Eu2+ phosphor was obtained at 1250 °C.There are two different types of Eu emission centers in Sr4Al14O25:Eu2+ phosphor.The effects of the Eu2+ concentration and the reducing temperature on the distribution of Eu2+ among different sites were investigated.The energy transfer mechanism between...
基金the National Natural Science Foundation of China(22178241,21908152 and 21978189)State Key Laboratory of Chemical Engineering,China(SKL-ChE-21A01).
文摘Mass transfer performance of gas–liquid two-phase flow at microscale is the basis of application of microreactor in gas–liquid reaction systems.At present,few researches on the mass transfer property of annular flow have been reported.Therefore,the mass transfer mechanism and relationship of gas–liquid annular flow in a microfluidic cross-junction device are studied in the present study.We find that the main factors,i.e.,flow pattern,liquid film thickness,liquid hydraulic retention time,phase interface fluctuation,and gas flow vorticity,which influence the flow mass transfer property,are directly affected both by gas and liquid flow velocities.But the influences of gas and liquid velocities on different mass transfer influencing factors are different.Thereout,the fitting relationships between gas and liquid flow velocities and mass transfer influencing factors are established.By comparing the results from calculations using fitting equations and simulations,it shows that the fitting equations have relatively high degrees of accuracy.Finally,the Pareto front,namely the Pareto optimal solution set,of gas and liquid velocity conditions for the best flow mass transfer property is obtained using the method of multi-objective particle swarm optimization.It is proved that the mass transfer property of the gas–liquid two-phase flow can be obviously enhanced under the guidance of the obtained Pareto optimal solution set through experimental verification.
基金Project(50621062) supported by the National Natural Science Foundation of China
文摘Prestressed high-strength-concrete (PHC) tube-shaped pile is one of the recently used foundations for soft soil. The research on uplift resistance of PHC pile is helpful to the design of pile foundations. A field-scale test program was conducted to study the uplift behavior and load transfer mechanism of PHC piles in soft soil. The pullout load tests were divided into two groups with different diameters, and there were three piles in each group. A detailed discussion of the axial load transfer and pile skin resistance distribution was also included. It is found from the tests that the uplift capacity increases with increasing the diameter of pile. When the diameter of piles increases from 500 to 600 mm, the uplift load is increased by 51.2%. According to the load-displacement (Q-S) curves, all the piles do not reach the ultimate state at the maximum load. The experimental results show that the piles still have uplift bearing capacity.
基金National Natural Science Foundation of China,Grant No.30972306 and 31270595
文摘The mass and heat transfer mechanisms during radio frequency/vacuum （RF/V） drying of square-edged timber were analyzed and discussed in detail, and a new one-dimensional mathematical model to describe the transport phenomena of mass and heat during continuous RF/V drying was derived from conservation equations based on the mass and heat transfer theory of porous materials The new model provided a relatively fast and efficient way to simulate vacuum drying behavior assisted by dielectric heating. Its advantages compared with the conventional models include： （1） Each independent vari- able has a separate control equation and is solved inde- pendently by converting the partial differential equation into a difference equation with the finite volume method; （2） The calculated data from different parts of the specimen can be displayed in the evolution curves, and the change law of the,parameters can be better described. After analyzing the calculated results, most of the important phenomena observed during RF/V drying were adequately described by this model.
文摘The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene（solvent）,Span-80（surfactant）and di-（2-ethylhexyl） phosphoricacid（HDEHP,carrier）.The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu（NO3）3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.
基金supported by the National Natural Science Foundation of China(No.52200049)the China Postdoctoral Science Foundation(No.2022TQ0089)+2 种基金the Heilongjiang Province Postdoctoral Science Foundation(No.LBH-Z22181)the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2024TS28)the Fundamental Research Funds for the Central Universities。
文摘The advanced oxidation system based on peracetic acid(PAA)has been proved to be a green and safe oxidation decontamination technology.Among them,the key challenge and complexity in current research lies in the directional induction of PAA and its utilization for selective removal of refractory pollutants.This study prepared nitrogen-doped biochar(NBC)using compound pharmaceutical residues commonly found in traditional Chinese medicine as a precursor.A system based on NBC-activated PAA was constructed for sulfamethoxazole(SMX)degradation.The introduction of nitrogen significantly enhanced the degree of graphitization in NBC.The degradation system achieved 87.89%SMX degradation efficiency within 60 min.Furthermore,the formation of the intricate NBC-PAA*complex detected by in-situ Raman was of paramount importance as it facilitates enhanced electron transfer processes within the complex,thereby promoting PAA decomposition through electron loss.The formation of a new complex between SMX and NBC-PAA*facilitated the completion of electron transfer process within the complex.In summary,this study explored a novel approach for treating and disposing of solid waste from Chinese medicine residue by successfully inducing non-free radical degradation pathway using PAA system.It offers fresh insights and ideas in the fields of water treatment and solid waste management.
基金support from the National Natural Science Foundation of China(Nos.U21A2034 and 21876052)the Guangdong Special Support Plan for Innovation Teams(No.2019BT02L218)+1 种基金the Guangdong Special Support Plan for Young Top-notch Talents(No.2019TQ05L179)the Natural Science Foundation of Guangdong Province,China(No.2021B1515120077)。
文摘Electrochemical nitrate reduction(NO_(3)RR)offers a promising avenue for treating nitrate-contaminated water and recovering ammonia(NH_(3)),yet the complexities of direct electron transfer(DET)and hydrogen atom transfer(HAT)mechanisms crucial for efficiency remain elusive.This study bridges the gap with a combined experimental and theoretical approach,elucidating the impact of catalyst structure on NO3RR pathways.We discover that catalysts favoring strong NO_(3^(-))adsorption and efficient water dissociation were more inclined towards DET,enhancing denitrification.The Fe@Fe_(3)O_(4)/FF cathode,leveraging the synergistic interplay between metallic Fe and Fe_(3)O_(4),excelled in NO3RR via DET,achieving an NH3yield of 0.28 mmol h-1cm-2and a Faradaic efficiency of 95.7%for NH3at-1.6 V(vs.SCE),with minimal nitrite accumulation at 100 mmol/L nitrate.Conversely,the Fe/FF and Fe_(3)O_(4)/CC cathodes showed reduced NH3production and increased nitrite levels,attributed to the lack of Fe_(3)O_(4)and metallic Fe,respectively,resulting in a dominant HAT mechanism.Moreover,Fe@Fe_(3)O_(4)/FF facilitated complete denitrification in real wastewater treatment by harnessing Cl^(-)for electrochemically mediated breakpoint chlorination.This research not only deepens our understanding of NO3RR mechanisms but also paves the way for designing superior nitrate reduction catalysts.
基金supported by the National Natural Science Foundation of China under Gramt No.51172252
文摘Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3＋ and Tm3＋Ho3＋） ion is proposed. Codoping of Tm3＋ or Ho3＋ significantly reduces the lifetime of the Era＋： 4I13/2 level due to the energy transfer of Er3＋：4I13/2 →Tm3＋：3F4 or Er3＋：4I13/2 →Ho3＋： 5I7. Thus, the 2.7μm emission is strengthened and the 1,5μm emission is decreased accordingly especially in the Era＋/Tma＋ sample. The upconversion effects between the Er3＋/Tm3＋ and Er3＋/Ho3＋ doped ZBYA glasses are different attribute to the different energy transfer efficiencies. Both of the two codoped samples possess nearly equal large emission cross section （16.6 × 10 -21 cm-2） around 2.7 μm. The results indicate that this Er3＋/Tm3＋ or Er3＋/Ho3＋ doped ZBYA glass has potential applications in 2.7 μm laser.
文摘The equilibrium and kinetic characteristics of the adsorption of erythromycin to Sepabeads SP825 were determined.The equilibrium data in a batch system was well described by a Langmuir isotherm.The separation performance was investigated in a fixed-bed system with respect to the adsorption superficial velocity,ionic strength and pH.A mathematical model was used to simulate the mass transfer mechanism,taking film mass transfer,pore diffusion and axial dispersion into account.The model predictions were consistent with the experi-mental data and were consequently used to determine the mass transfer coefficients.
基金supported by the Haiyou Program for Industry Leading Talent Innovation Team Project(No.1362022088)。
文摘A novel inverted advanced treatment process of ozone/hydrogen peroxide(O_(3)/H_(2)O_(2))and biological activated carbon fluidized bed(BACFB)before the conventional process has been developed to treat the high-algae-laden reservoir water,which aims to enhance the removal of dissolved organic matter(DOM),odorants as well as the precursors of disinfection by-products(DBPs).Before and after the renovation,the average value of chemical oxygen demand(determined by potassium permanganate method)in the filter effluent decreased from 2.18 to 1.15 mg/L.Likewise,the average concentrations of turbidity dropped from 0.640 to 0.098 NTU,indicating substantial improvement following the renovation.Formation potential of DBPs such as trihalomethanes and haloacetic acids were also reduced greatly.The results of the polarity rapid analysis method indicated that ozonation primarily removed non-polar and positively charged organic matter,while coagulation-sedimentation targeted non-positive organic matter.The results of fluorescence spectroscopy and highresolution mass spectrometry indicated that the new process effectively removed DOM,and decreased the number of nitrogen-containing compounds.Additionally,the inverted O_(3)/H_(2)O_(2) and BACFB process promoted the dynamic transformation between DOM components and significantly reduced overall aromatic content.This study provided a promising solution for treating high-algae-laden source water and verified the feasibility and effectiveness of this novel process in practice.
文摘The phase transfer mechanism of 18-molybdophosphate anion at the water/nitrobenzene interfaca has been investigated by chronopotentiometry with cyclic linear current-scanning (CLC) and cyclic voltammetry (CV). The transfer species is 18-molybdophosphtae anion with a charge number of-4, H_2[P_2Mo_(18)O_(62)]^(4-). The transfer process is controlled by diffusion at a slow polarization rate and considerably influenced by pH of the aqueous phase. The stable forms and pH range of the heteropoly anion in the aqueous solution can be directly confirmed through voltammetric behavior. The theoretical analysis of the relationship between the transfer potential and solution pH is identical to the experimental results. The linear concentration relationship with the transfer peak current is suggested to be used in the determination of heteropoly acids(salts).
文摘The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional. The complex is connected through two different types of inter-molecular hydrogen bonds. After photo-excitation, both hydrogen bonds get strengthened, which can facilitate the ESDPT reaction. The scanned potential energy curve along the proton transfer coordinate indicates that the ESDPT reaction proceeds in a stepwise pattern.
基金funded by the National Natural Science Foundation of China (NNSFC grant nos. 52103034, 51873126, 52175331 and 52003170)Shandong Provincial Natural Science Foundation (ZR2021QE014, ZR2020ZD04)
文摘Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.
基金Project supported by the National Key Foundation for Exploring Scientific Instrument of China(2014YQ120351)National Natural Science Foundation of China(11504266,51702235,51871167)the Natural Science Foundation of Tianjin,China(17JCQNJC02300,18JCYBJC86200)。
文摘Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.
文摘In order to clarify the mechanism and main influencing factors of the vibration energy coupling transmission with a dual-piston structure,a thermodynamic and dynamic coupling model of the free piston linear generator(FPLG)was established.The system energy conversion,vibration energy coupling transmission,and influencing factors were studied in detail.The coupling transmission paths and the secondary influence mechanism from in-cylinder combustion on vibration energy transmission were obtained.In addition,the influence of the movement characteristics of the dual-piston on the vibration energy transmission was studied,and the typical parameter variation law was obtained,which provides theoretical guidance for the subsequent vibration reduction design of the FPLG.
基金This project supported by the National Natural Science Foundation of China.
文摘Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the conditions of [TU]/[PPAO]<0.5 molar ratio isThe molecular weights of the polymers were found to be inversely proportional to 3/2-power of nitric acid concentration and 1-power of thiourea concentration. In addition, it is independent with the concentrations of monomer and PPAO, and decreases with increasing temperature.On the basis of these experimental results, a coordination-proton transfer mechanism for the initiation was proposed and discussed.
