Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow ...Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow operation temperature window.In this study,the trace amounts of Cu are used to modify a Pt/Al_(2)O_(3)catalyst.The introduced Cu_(2+)species are atomically anchored on Pt nanoparticles through strong electrostatic adsorption.展开更多
Aqueous zinc-ion batteries have emerged as promising candidates in next-generation energy storage sys-tems.However,their practical implementation is significantly hindered by interfacial side reactions,par-ticularly t...Aqueous zinc-ion batteries have emerged as promising candidates in next-generation energy storage sys-tems.However,their practical implementation is significantly hindered by interfacial side reactions,par-ticularly the hydrogen evolution reaction(HER)at the Zn metal anode interface.Herein,this study presents an innovative approach to address this challenge through the construction of an interfacial pref-erential coordination layer on the Zn anode surface.The proposed layer effectively terminates the conti-nuity of interfacial hydrogen-bond networks and blocks proton transport,thereby mitigating the HER.Specifically,2-phenylbenzimidazole-5-sulfonic acid(PBSA)with zincophilic groups was introduced as an electrolyte additive,which would be preferentially and selectively anchored on the Zn surface through its zincophilic nitrogen and sulfonic acid,forming the interfacial coordination layer.This coordination layer serves as a protective barrier,repelling water molecules from the Zn electrode surface and alleviat-ing water decomposition.Crucially,the interfacial coordination layer features stronger hydrogen-bonding interactions with interfacial water molecules,terminates the hydrogen-bonding network between water molecules,hinders the transportation and electro-reduction of proton,and ultimately inhibits HER at the interface.As a result,the Zn symmetric cell with PBSA/ZnSO_(4)delivered higher cycling stability of 2500 h at 1 mA cm^(-2)and Zn/NH_(4)V_(4)O_(10)full cells with PBSA/ZnSO_(4)possessed enhanced capac-ity retention.This interfacial hydrogen-bond regulation strategy provided valuable insight for designing HER-free interfacial protective layer in high-performance aqueous batteries.展开更多
The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hinde...The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.展开更多
Li plating behavior of the Li metal anode and its compatibility with electrolytes play a decisive role in the electrochemical performance of the Li metal batteries(LMBs),while the intrinsic highly reactive Li would in...Li plating behavior of the Li metal anode and its compatibility with electrolytes play a decisive role in the electrochemical performance of the Li metal batteries(LMBs),while the intrinsic highly reactive Li would induce serious results especially under deep Li plating/stripping depth and with lean electrolytes.Herein,we propose an innovative strategy to simultaneously regulate the bulk construction and the preferential orientation of Li deposition by introducing Li22Sn5/Li-Mg alloys to realize ultra-stable thin Li anodes with long lifespan.The alloys can form a continuous framework with high lithiophilicity and fast ion-diffusion to enable homogenous Li flux,and meanwhile tune the preferential orientation of Li from the conventional(110)plane to(200)to lower the Li reactivity with electrolytes and optimize Li deposition.Therefore,the thin Li-Sn-Mg alloy anode showcases ultra-stable cycling without volume changes and dendrites under a deep Li plating/stripping depth of 89.1%(5 mAh cm^(-2))for over 1200 h in commercial carbonate electrolytes.Moreover,a multilayered NCM811pouch cell with a high energy density of403.6 Wh kg^(-1)is achieved under the harsh conditions of low N/P ratio(0.769)and lean electrolytes(~2.1 g Ah^(-1)).Synchronously,the thin alloy anode shows improved air stability which benefits the manufacturing process and performance of LMBs,displaying the great application potential of these alloy anodes.展开更多
Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO thr...Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO through the deposition of Ru/Ir nanojunctions on Fe_(2)O_(3) nanoparticles.The as-prepared catalyst shows 90%CO conversion at 80℃ within the working temperature of PEMFCs and the total CO conversion in the temperature range of 140℃ to 160℃under gas flow velocity of 36000 mL·g^(−1)h^(−1) while maintaining good stability for 24 h.Density functional theory calculations reveal that the substrate Fe_(2)O_(3) not only serves as a source of lattice oxygen atoms for the catalytic process but also acts as an electron acceptor from Ru/Ir,thereby regulating its valence state.This regulation is beneficial for the adsorption of reaction intermediates and reduces the activation energy of PROX.展开更多
Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the under...Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.展开更多
To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between...To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between soil preferential pathways and soil matrices.RLD and RB declined with the increasing soil depth（0–10,10–20,20–30,30–40,40–50,50–60 cm） in all experimental plots.RLD was greater in soil preferential pathways than in the surrounding soil matrix and was 69.5,75.0 and72.2 % for plant roots of diameter（d） ／1,1 ／ d ／ 3 and3 ／ d ／ 5 mm,respectively.Fine root systems had the most pivotal influence on soil preferential flow in this forest ecosystem.In all experimental plots,RB content was the sum of RB from soil preferential pathways and the soil matrix in each soil depth.With respect to 6 soil depth gradient（0–10,10–20,20–30,30–40,40–50,50–60 cm） in each plot,the number of soil depth gradient that RB content was greater in soil preferential pathways than in the soil matrix was characterized,and the proportion was68.2 % in all plots.展开更多
The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both...The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both dump permeability and surface tension and ore diameter. The preferential solution flow occured in the fine ore area when the application rate was low. The preferential solution flow entered into the coarse ore area because the negative pore water pressure disappeared with an increase of the application rate. The preferential solute transportation experiment was conducted by selecting NaCl as mineral. Results of the experiment showed that the concentration of the outflow solution reduced over time. The concentration of the coarse ore area outflow solution was greater than that of the fine ore area. The process of NaCl leaching can be divided into two stages. NaCl was carried out directly by diffusion--convection during the first stage, so the leaching rate increased sharply. But in the second stage, only a small amount of NaCl dissolved in the immobile water. The leaching rate increased slowly because NaC1, dissolved in the immobile water, can only be leached by diffusion.展开更多
Binary mixtures of 1,3-dialkylimidazolium based ionic liquids （ILs） and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solv...Binary mixtures of 1,3-dialkylimidazolium based ionic liquids （ILs） and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators at 25 ℃. Empirical solvatochromic pa- rameters, dipolarity/polarizability （π^＊）, hydrogen-bond donor acidity （α）, hydrogen-bond acceptor basicity （β）, and Reichardt＇s polarity parameters （ET^N） were measured from the ultraviolet-visible spectral shifts of 4-nitroaniline, 4-nitroanisole, and Reichardt＇s dye. The solvent properties of the IL-water mixtures were found to be influenced by IL type and IL mole fraction （XIL）. All these studied systems showed the non-ideal behavior. The max- imum deviation to ideality for the solvatochromic parameters can be obtained in the XIL range from 0.i to 0.3. For most of the binary mixtures, the π^＊ values showed the synergistic effects instead of the ETN, α and β values. The observed synergy extent was dependent on the studied systems, such as the dye indicator and IL type. A preferential solvation model was utilized to gather information on the molecular interactions in the mixtures. The dye indicator was preferentially solvated on the following trend： IL〉IL-water complex〉water.展开更多
We selected a dark coniferous forest ecosystem of Gongga Mountain in the upper reaches of the Yangtze River as our research area to study the preferential flow and solute preferential transport by adding the tracers K...We selected a dark coniferous forest ecosystem of Gongga Mountain in the upper reaches of the Yangtze River as our research area to study the preferential flow and solute preferential transport by adding the tracers KNO3 and KBr to the self-made soil column equipment in different ways to examine density and volume changes of inflows and outflows of a mass input （impulse input） and a stable, well-distributed input （step input））. The results showed that this dark coniferous forest ecosystem of Gongga Mountain is a typical area of preferential flow and solute preferential transport, a process that can be classified into five parts. A great amount of solute was transported at high speed as the result of preferential flow in the soil and caused the density of the solute in both deep water and in groundwater to rise rapidly, which definitely increased pollution in the deep soil layer.展开更多
The preferential oxidation of CO （CO‐PROX） is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells （PEMFCs）. Au catalysts are highly active in CO oxidation. Howev‐er, their activities ...The preferential oxidation of CO （CO‐PROX） is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells （PEMFCs）. Au catalysts are highly active in CO oxidation. Howev‐er, their activities still need to be improved at the PEMFC operating temperatures of 80–120 ＆#176;C. In the present study, Au nanoparticles of average size 2.6 nm supported on ceria‐modified Al2O3 were synthesized and characterized using powder X‐ray diffraction, nitrogen physisorption, transmission electron and scanning transmission electron microscopies, temperature‐programmed hydrogen reduction （H2‐TPR）, Raman spectroscopy, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy. Highly dispersed Au nanoparticles and strong structures formed by Au–support in‐teractions were the main active species on the ceria surface. The Raman and H2‐TPR results show that the improved catalytic performance of the Au catalysts can be attributed to enhanced strong metal–support interactions and the reducibility caused by ceria doping. The formation of oxygen vacancies on the catalysts increased their activities in CO‐PROX. The synthesized Au catalysts gave excellent catalytic performances with high CO conversions （＆gt;97%） and CO2 selectivities （＆gt;50%） in the temperature range 80–150 ＆#176;C.展开更多
Based on the preferential continuation method proposed by Pawlowski （1995）, we propose a method and procedure for gravity anomaly separation with the preferential upward continuation operator in the case that the va...Based on the preferential continuation method proposed by Pawlowski （1995）, we propose a method and procedure for gravity anomaly separation with the preferential upward continuation operator in the case that the various sources are uncorrelated with one another and the continuation height is enough large. We also present a method for estimating optimum upward-continuation height, based on analyzing the characteristics of the preferential upward continuation operators of a synthesized gravity anomaly varying with different continuation heights. The method is tested on the raw Bouguer gravity data over an iron deposit. The result shows that the method separates the data into regional anomaly and residual anomaly efficiently and clearly.展开更多
Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil pr...Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.展开更多
The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min we...The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction method.The results show that grain growth takes place gradually with the annealing time increasing.Moreover,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity area.Grains with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture changes.The original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.展开更多
The aim of this paper is to review the major points of contention concerning secondary petroleum migration, to discuss the nature and primary controls of the positions of petroleum migration pathways in sedimentary ba...The aim of this paper is to review the major points of contention concerning secondary petroleum migration, to discuss the nature and primary controls of the positions of petroleum migration pathways in sedimentary basins, and to illustrate the importance of preferential petroleum migration pathways for the formation of large oil/gas fields away from generative kitchens. There is competition between the driving force （buoyancy） and the restraining force （capillary pressure controlled largely by permeability contrast） in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. At a large scale, there is a critical angle of dip of the carrier beds which determines the relative importance of structural morphology or permeability contrasts in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. Maximum-driving-force-controlled migration pathways occur in carrier beds with an angle of dip greater than the critical dip and the positions of petroleum migration pathways are controlled mainly by the morphology of the sealing surfaces. Minimum-restraining-force-determined migration pathways occur in carrier beds with an angle of dip smaller than the critical angle where permeability contrasts would exert a more important influence on the positions of petroleum migration pathways. Preferential petroleum migration pathways （PPMP）, defined as very restricted portions of carrier-beds that focus or concentrate petroleum from a large area of the generative kitchen, determine the distribution of oil and gas in sedimentary basins. The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions, but also for the formation of large oil or gas fields. Regions may miss out on petroleum migration because of its three-dimensional behavior, and two-dimensional migration modeling may be misleading in predicting petroleum occurrences in certain circumstances.展开更多
A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil. After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling ...A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil. After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned, the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred, because heterogeneity of soil, one of the mechanisms resulting in preferential flow, could be reflected through the difference in saturated hydraulic conductivity. The modeling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile. The results of the numerical simulation showed that the approach suggested in this study was feasible.展开更多
Influence of three different preparation methods, i.e. impregnation, coprecipitation, and inverse coprecipitation, on the preferential oxidation of CO in excess hydrogen （PROX） over CuO-CeO2 catalysts has been inves...Influence of three different preparation methods, i.e. impregnation, coprecipitation, and inverse coprecipitation, on the preferential oxidation of CO in excess hydrogen （PROX） over CuO-CeO2 catalysts has been investigated and CuO-CeO2 catalysts are characterized using BET, XPS, XRD, UV Raman, and TPR techniques. The results show that the catalysts prepared by coprecipitation have smaller particle sizes, well-dispersed CuOx species, more oxygen vacancies, and are more active in the PROX than those prepared by the other methods. However. the inverse coprecipitation depresses the catalytic performance of CuO-CeO2 catalysts and causes the growth of CuO-CeO2 because of different pH value in the precipitation process.展开更多
Preferential flow is a rapid movement of solution through pores caused by coarse ores. Macropore is the main factor for the preferential flow. Macropore can be defined from three aspects. Segregation of the ores durin...Preferential flow is a rapid movement of solution through pores caused by coarse ores. Macropore is the main factor for the preferential flow. Macropore can be defined from three aspects. Segregation of the ores during dumping was studied according to particle kinematics. Small ores become smaller under the effect of acid and weathering. Clay in the rainwater from the hillside precipitates in the dump. Segregation and fine ores are the main causes in macropore. The permeability in coarse ores is better than that in fine ores. The mechanism in the preferential flows was studied combining the fast conducting effect of the macropore. Experimental result shows that, at certain application rate, fine ore area is saturated while large volume of solution flows laterally to the coarse ore area and leaks out quickly through the macropores. Thus the mechanism of preferential solution flows is further illustrated.展开更多
This work described in situ combustion synthesis method for depositing CuO-CeO2 on the FeCrAI honeycomb supports. The influence of the solution concentration and the role of the additive were studied and analyzed by s...This work described in situ combustion synthesis method for depositing CuO-CeO2 on the FeCrAI honeycomb supports. The influence of the solution concentration and the role of the additive were studied and analyzed by scanning electron microscopy （SEM）, X-ray diffractometer （XRD）, and temperature programmed reduction （TPR） techniques. The results showed that 200 g/L of the active solution was the most appropriate concentration for preparing the monolithic catalysts, and the additives of praseodymium and lanthanum improved the adhesion stability of the monolithic catalysts. The addition of Pr did not greatly affect the catalytic performance, but CO could not be totally converted into CO2 after the addition of La into the CuO-CeO2/Al2O3/FeCrAl catalysts.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3504200)the National Natural Science Foundation of China(Nos.U21A20326 and 22376063)+4 种基金the fund of the National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2020A05)the Fundamental Research Funds for the Central Universitiesthe funding received from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 897197.Y.L.(CSC No.202006740085)is grateful for thegrant from the China Scholarship Councilthe ICREA Academia program and grants MICINN/FEDER PID2021124572OB-C31 and GC 2021 SGR 01061part of Maria de Maeztu Units of Excellence Programme CEX2023-001300-M/funded by MCIN/AEI/https://doi.org/10.13039/501100011033
文摘Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow operation temperature window.In this study,the trace amounts of Cu are used to modify a Pt/Al_(2)O_(3)catalyst.The introduced Cu_(2+)species are atomically anchored on Pt nanoparticles through strong electrostatic adsorption.
基金supported by financial support from the National Natural Science Foundation of China(Grant No.22225801 and 22461142137).
文摘Aqueous zinc-ion batteries have emerged as promising candidates in next-generation energy storage sys-tems.However,their practical implementation is significantly hindered by interfacial side reactions,par-ticularly the hydrogen evolution reaction(HER)at the Zn metal anode interface.Herein,this study presents an innovative approach to address this challenge through the construction of an interfacial pref-erential coordination layer on the Zn anode surface.The proposed layer effectively terminates the conti-nuity of interfacial hydrogen-bond networks and blocks proton transport,thereby mitigating the HER.Specifically,2-phenylbenzimidazole-5-sulfonic acid(PBSA)with zincophilic groups was introduced as an electrolyte additive,which would be preferentially and selectively anchored on the Zn surface through its zincophilic nitrogen and sulfonic acid,forming the interfacial coordination layer.This coordination layer serves as a protective barrier,repelling water molecules from the Zn electrode surface and alleviat-ing water decomposition.Crucially,the interfacial coordination layer features stronger hydrogen-bonding interactions with interfacial water molecules,terminates the hydrogen-bonding network between water molecules,hinders the transportation and electro-reduction of proton,and ultimately inhibits HER at the interface.As a result,the Zn symmetric cell with PBSA/ZnSO_(4)delivered higher cycling stability of 2500 h at 1 mA cm^(-2)and Zn/NH_(4)V_(4)O_(10)full cells with PBSA/ZnSO_(4)possessed enhanced capac-ity retention.This interfacial hydrogen-bond regulation strategy provided valuable insight for designing HER-free interfacial protective layer in high-performance aqueous batteries.
基金Under the auspices of the Natural Science Foundation of China(No.42272299)The Key Projects of Jilin Provincial Department of Science and Technology(No.20240203004NC)+1 种基金National Key Research and Development Program of China(No.2022YFD1500500)Graduate Innovation Fund of Jilin University(No.2024CX111)。
文摘The freeze-thaw process is crucial for forming soil macropore structure to promote movement of water and salt downward by preferential flow in seasonally frozen regions.However,the freeze-thaw process of soil is hindered by the snowpack,and the effects of the snowpack on the soil macropore structure and its implications on the formation of preferential flow are not well understood.This study collected soil samples from Da’an City,Northeast China,on July 15 and 16,2022,and conducted an indoor soil column snowpack-freeze-thaw tracing experiment on October 10 to 30,2022,to reveal the impact of snowpack and freeze-thaw cycles(FTC)on the forma-tion of preferential flow.The experiments were carried out with three levels of initial moisture content(IMC)of the soil column,the times of freeze-thaw cycles(T-FTC),and the snowpack thickness(SPT).Results show that increases in both IMC and SPT decreased the max infiltration depth(MID)of preferential flow.Greater T-FTC increased the MID and non-uniformity of the wet front trace and promoted the creation of preferential flow.The T-FTC and IMC both increased the overall variability of preferential flow,but this vari-ability decreased with greater SPT.The length index(LI)had the most significant impact on the preferential flow index(PFI)with an entropy weight of 0.2340,while the height difference of the multifractal spectrum(Δf(α))had the most negligible impact with a weight of 0.0753.Finally,results of redundancy analysis(RDA)and structural equation model(SEM)show that multifractal characteristic in-dicators have a much stronger ability to reflect the degree of preferential flow than developmental characteristic indicators.The T-FTC was the most important factor driving the formation of preferential flow in snowpack-freeze-thaw cycles.Therefore,conducting re-search on preferential flow in cold and arid regions is greatly significant for the utilization of regional water resources and the improve-ment of soil ecological environments.
基金supported by the Jilin Province Science and Technology Department Major Science and Technology project[grant numbers 20220301004GX,20220301005GX]Key Subject Construction of Physical Chemistry of Northeast Normal Universitythe Fundamental Research Funds for the Central Universities[grant number 2412023QD014]。
文摘Li plating behavior of the Li metal anode and its compatibility with electrolytes play a decisive role in the electrochemical performance of the Li metal batteries(LMBs),while the intrinsic highly reactive Li would induce serious results especially under deep Li plating/stripping depth and with lean electrolytes.Herein,we propose an innovative strategy to simultaneously regulate the bulk construction and the preferential orientation of Li deposition by introducing Li22Sn5/Li-Mg alloys to realize ultra-stable thin Li anodes with long lifespan.The alloys can form a continuous framework with high lithiophilicity and fast ion-diffusion to enable homogenous Li flux,and meanwhile tune the preferential orientation of Li from the conventional(110)plane to(200)to lower the Li reactivity with electrolytes and optimize Li deposition.Therefore,the thin Li-Sn-Mg alloy anode showcases ultra-stable cycling without volume changes and dendrites under a deep Li plating/stripping depth of 89.1%(5 mAh cm^(-2))for over 1200 h in commercial carbonate electrolytes.Moreover,a multilayered NCM811pouch cell with a high energy density of403.6 Wh kg^(-1)is achieved under the harsh conditions of low N/P ratio(0.769)and lean electrolytes(~2.1 g Ah^(-1)).Synchronously,the thin alloy anode shows improved air stability which benefits the manufacturing process and performance of LMBs,displaying the great application potential of these alloy anodes.
基金financially supported by the National Natural Science Foundation of China(No.22072140,No.22272155,and No.22102169)the National Key R&D Program of China(No.2021YFA1600202)。
文摘Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO through the deposition of Ru/Ir nanojunctions on Fe_(2)O_(3) nanoparticles.The as-prepared catalyst shows 90%CO conversion at 80℃ within the working temperature of PEMFCs and the total CO conversion in the temperature range of 140℃ to 160℃under gas flow velocity of 36000 mL·g^(−1)h^(−1) while maintaining good stability for 24 h.Density functional theory calculations reveal that the substrate Fe_(2)O_(3) not only serves as a source of lattice oxygen atoms for the catalytic process but also acts as an electron acceptor from Ru/Ir,thereby regulating its valence state.This regulation is beneficial for the adsorption of reaction intermediates and reduces the activation energy of PROX.
基金financially supported by the National Natural Science Foundation of China(22468034)the Natural Science Foundation of Inner Mongolia(2021MS02008 and 2022MS02011)the Key Research and Development Project of Ordos(YF20240062)。
文摘Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.
基金supported by a grant from the Natural Science Foundation of China(41271044)
文摘To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between soil preferential pathways and soil matrices.RLD and RB declined with the increasing soil depth（0–10,10–20,20–30,30–40,40–50,50–60 cm） in all experimental plots.RLD was greater in soil preferential pathways than in the surrounding soil matrix and was 69.5,75.0 and72.2 % for plant roots of diameter（d） ／1,1 ／ d ／ 3 and3 ／ d ／ 5 mm,respectively.Fine root systems had the most pivotal influence on soil preferential flow in this forest ecosystem.In all experimental plots,RB content was the sum of RB from soil preferential pathways and the soil matrix in each soil depth.With respect to 6 soil depth gradient（0–10,10–20,20–30,30–40,40–50,50–60 cm） in each plot,the number of soil depth gradient that RB content was greater in soil preferential pathways than in the soil matrix was characterized,and the proportion was68.2 % in all plots.
基金Project 50325415 supported by the National Science Fund for Distinguished Young Scholars, 50574099 and 50321402 by the National Natural ScienceFoundation of China and 2004CB619205 by the National Key Fundamental Research and Development Program
文摘The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both dump permeability and surface tension and ore diameter. The preferential solution flow occured in the fine ore area when the application rate was low. The preferential solution flow entered into the coarse ore area because the negative pore water pressure disappeared with an increase of the application rate. The preferential solute transportation experiment was conducted by selecting NaCl as mineral. Results of the experiment showed that the concentration of the outflow solution reduced over time. The concentration of the coarse ore area outflow solution was greater than that of the fine ore area. The process of NaCl leaching can be divided into two stages. NaCl was carried out directly by diffusion--convection during the first stage, so the leaching rate increased sharply. But in the second stage, only a small amount of NaCl dissolved in the immobile water. The leaching rate increased slowly because NaC1, dissolved in the immobile water, can only be leached by diffusion.
文摘Binary mixtures of 1,3-dialkylimidazolium based ionic liquids （ILs） and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators at 25 ℃. Empirical solvatochromic pa- rameters, dipolarity/polarizability （π^＊）, hydrogen-bond donor acidity （α）, hydrogen-bond acceptor basicity （β）, and Reichardt＇s polarity parameters （ET^N） were measured from the ultraviolet-visible spectral shifts of 4-nitroaniline, 4-nitroanisole, and Reichardt＇s dye. The solvent properties of the IL-water mixtures were found to be influenced by IL type and IL mole fraction （XIL）. All these studied systems showed the non-ideal behavior. The max- imum deviation to ideality for the solvatochromic parameters can be obtained in the XIL range from 0.i to 0.3. For most of the binary mixtures, the π^＊ values showed the synergistic effects instead of the ETN, α and β values. The observed synergy extent was dependent on the studied systems, such as the dye indicator and IL type. A preferential solvation model was utilized to gather information on the molecular interactions in the mixtures. The dye indicator was preferentially solvated on the following trend： IL〉IL-water complex〉water.
基金the financial support provided by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20060022006)National Natural Sciences Foundation of China (Grant No. 30471379)
文摘We selected a dark coniferous forest ecosystem of Gongga Mountain in the upper reaches of the Yangtze River as our research area to study the preferential flow and solute preferential transport by adding the tracers KNO3 and KBr to the self-made soil column equipment in different ways to examine density and volume changes of inflows and outflows of a mass input （impulse input） and a stable, well-distributed input （step input））. The results showed that this dark coniferous forest ecosystem of Gongga Mountain is a typical area of preferential flow and solute preferential transport, a process that can be classified into five parts. A great amount of solute was transported at high speed as the result of preferential flow in the soil and caused the density of the solute in both deep water and in groundwater to rise rapidly, which definitely increased pollution in the deep soil layer.
基金supported by the National Basic Research Program of China (973 Program, 2013CB934104)the National Natural Science Founda-tion of China (21225312, U1303192)~~
文摘The preferential oxidation of CO （CO‐PROX） is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells （PEMFCs）. Au catalysts are highly active in CO oxidation. Howev‐er, their activities still need to be improved at the PEMFC operating temperatures of 80–120 ＆#176;C. In the present study, Au nanoparticles of average size 2.6 nm supported on ceria‐modified Al2O3 were synthesized and characterized using powder X‐ray diffraction, nitrogen physisorption, transmission electron and scanning transmission electron microscopies, temperature‐programmed hydrogen reduction （H2‐TPR）, Raman spectroscopy, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy. Highly dispersed Au nanoparticles and strong structures formed by Au–support in‐teractions were the main active species on the ceria surface. The Raman and H2‐TPR results show that the improved catalytic performance of the Au catalysts can be attributed to enhanced strong metal–support interactions and the reducibility caused by ceria doping. The formation of oxygen vacancies on the catalysts increased their activities in CO‐PROX. The synthesized Au catalysts gave excellent catalytic performances with high CO conversions （＆gt;97%） and CO2 selectivities （＆gt;50%） in the temperature range 80–150 ＆#176;C.
基金supported jointly by projects of the 863 Program (Grant Nos.2006AA06Z111,2006AA06A201-3,and 20060109A1002-0201-03)
文摘Based on the preferential continuation method proposed by Pawlowski （1995）, we propose a method and procedure for gravity anomaly separation with the preferential upward continuation operator in the case that the various sources are uncorrelated with one another and the continuation height is enough large. We also present a method for estimating optimum upward-continuation height, based on analyzing the characteristics of the preferential upward continuation operators of a synthesized gravity anomaly varying with different continuation heights. The method is tested on the raw Bouguer gravity data over an iron deposit. The result shows that the method separates the data into regional anomaly and residual anomaly efficiently and clearly.
基金Project supported by the National Key Basic Research Support FOundation(NKBRSF) of China(No.G19990ll708) and the Guangxi Uni,rsitv Science funds China(No.1701).
文摘Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.
基金financial supports from the National Natural Science Foundation of China(NSFC,No.51601193)State Key Program of National Natural Science of China(No.51531002)+1 种基金National Key Research and Development Program of China(No.2016YFB0301104)National Basic Research Program of China(973 Program,No.2013CB632202)。
文摘The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction method.The results show that grain growth takes place gradually with the annealing time increasing.Moreover,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity area.Grains with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture changes.The original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.
基金supported by the National Natural Science Foundation of China (grant No. 90914006)Program for Changjiang Scholars and Innovative Research Team in the University (IRT0658)
文摘The aim of this paper is to review the major points of contention concerning secondary petroleum migration, to discuss the nature and primary controls of the positions of petroleum migration pathways in sedimentary basins, and to illustrate the importance of preferential petroleum migration pathways for the formation of large oil/gas fields away from generative kitchens. There is competition between the driving force （buoyancy） and the restraining force （capillary pressure controlled largely by permeability contrast） in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. At a large scale, there is a critical angle of dip of the carrier beds which determines the relative importance of structural morphology or permeability contrasts in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. Maximum-driving-force-controlled migration pathways occur in carrier beds with an angle of dip greater than the critical dip and the positions of petroleum migration pathways are controlled mainly by the morphology of the sealing surfaces. Minimum-restraining-force-determined migration pathways occur in carrier beds with an angle of dip smaller than the critical angle where permeability contrasts would exert a more important influence on the positions of petroleum migration pathways. Preferential petroleum migration pathways （PPMP）, defined as very restricted portions of carrier-beds that focus or concentrate petroleum from a large area of the generative kitchen, determine the distribution of oil and gas in sedimentary basins. The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions, but also for the formation of large oil or gas fields. Regions may miss out on petroleum migration because of its three-dimensional behavior, and two-dimensional migration modeling may be misleading in predicting petroleum occurrences in certain circumstances.
基金Project supported by the National Natural Science Foundation of China (No. 49971041), the National KeyBasic Research and Devel
文摘A simple modeling approach was suggested to simulate preferential transport of water and contaminants in soil. After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned, the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred, because heterogeneity of soil, one of the mechanisms resulting in preferential flow, could be reflected through the difference in saturated hydraulic conductivity. The modeling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile. The results of the numerical simulation showed that the approach suggested in this study was feasible.
文摘Influence of three different preparation methods, i.e. impregnation, coprecipitation, and inverse coprecipitation, on the preferential oxidation of CO in excess hydrogen （PROX） over CuO-CeO2 catalysts has been investigated and CuO-CeO2 catalysts are characterized using BET, XPS, XRD, UV Raman, and TPR techniques. The results show that the catalysts prepared by coprecipitation have smaller particle sizes, well-dispersed CuOx species, more oxygen vacancies, and are more active in the PROX than those prepared by the other methods. However. the inverse coprecipitation depresses the catalytic performance of CuO-CeO2 catalysts and causes the growth of CuO-CeO2 because of different pH value in the precipitation process.
基金Project (50321402) supported by China Science Fundfor Distinguished Groupproject (2004CB619200) supported bytheNational Key Fundamental Research and Development Programof China +1 种基金project (50325415) supported by the National Science Fund forDistinguished Young Scholars of China project(50574099)supported by the National Natural Science Foundation of China
文摘Preferential flow is a rapid movement of solution through pores caused by coarse ores. Macropore is the main factor for the preferential flow. Macropore can be defined from three aspects. Segregation of the ores during dumping was studied according to particle kinematics. Small ores become smaller under the effect of acid and weathering. Clay in the rainwater from the hillside precipitates in the dump. Segregation and fine ores are the main causes in macropore. The permeability in coarse ores is better than that in fine ores. The mechanism in the preferential flows was studied combining the fast conducting effect of the macropore. Experimental result shows that, at certain application rate, fine ore area is saturated while large volume of solution flows laterally to the coarse ore area and leaks out quickly through the macropores. Thus the mechanism of preferential solution flows is further illustrated.
基金Project supported by the National Key Basic Research Program (973 Program,2009CB226112)National Natural Science Foundation of China (21066004)Scientific Research Start Foundation of High-level Introduction Talent of Inner Mongolia University(Grant No.207062) for funding this research
文摘This work described in situ combustion synthesis method for depositing CuO-CeO2 on the FeCrAI honeycomb supports. The influence of the solution concentration and the role of the additive were studied and analyzed by scanning electron microscopy （SEM）, X-ray diffractometer （XRD）, and temperature programmed reduction （TPR） techniques. The results showed that 200 g/L of the active solution was the most appropriate concentration for preparing the monolithic catalysts, and the additives of praseodymium and lanthanum improved the adhesion stability of the monolithic catalysts. The addition of Pr did not greatly affect the catalytic performance, but CO could not be totally converted into CO2 after the addition of La into the CuO-CeO2/Al2O3/FeCrAl catalysts.
