As an important factor that directly affects agricultural production, the social economy, and policy implementation,observed changes in dry/wet conditions have become a matter of widespread concern. However, previous ...As an important factor that directly affects agricultural production, the social economy, and policy implementation,observed changes in dry/wet conditions have become a matter of widespread concern. However, previous research has mainly focused on the long-term linear changes of dry/wet conditions, while the detection and evolution of the non-linear trends related to dry/wet changes have received less attention. The non-linear trends of the annual aridity index, obtained by the Ensemble Empirical Mode Decomposition(EEMD) method, reveal that changes in dry/wet conditions in China are asymmetric and can be characterized by contrasting features in both time and space in China. Spatially, most areas in western China have experienced transitions from drying to wetting, while opposite changes have occurred in most areas of eastern China. Temporally, the transitions occurred earlier in western China compared to eastern China. Research into the asymmetric spatial characteristics of dry/wet conditions compensates for the inadequacies of previous studies, which focused solely on temporal evolution;at the same time, it remedies the inadequacies of traditional research on linear trends over centennial timescales. Analyzing the non-linear trend also provides for a more comprehensive understanding of the drying/wetting changes in China.展开更多
Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breedin...Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breeding and cultivation to improve nutritional quality.However,little information is available on differences in lysine anabolism between SG and IG and the underlying mechanism,and whether and how irrigation regimes affect lysine anabolism in these grains.A japonica rice cultivar was grown in the field and two irrigation regimes,continuous flooding(CF)and wetting alternating with partial drying(WAPD),were imposed from heading to the mature stage.Lysine content and activities of key enzymes of lysine biosynthesis,and levels of brassinosteroids(BRs)were lower in the IG than in the SG at the early grainfilling stage but higher at middle and late grain-filling stages.WAPD increased activities of these key enzymes,BR levels,and contents of lysine and total amino acids in IG,but not SG relative to CF.Application of 2,4-epibrassinolide to rice panicles in CF during early grain filling reproduced the effects of WAPD,but neither treatment altered the activities of enzymes responsible for lysine catabolism in either SG or IG.WAPD and elevated BR levels during grain filling increased lysine biosynthesis in IG.Improvement in lysine biosynthesis in rice should focus on IG.展开更多
In this study,the perovskite nanocomposite PrFe_(x)Co_(1-x)O_(3)(Pr(S))was successfully synthesized by the sol-gel method;PrFe_(x)Co_(1-x)O_(3)/Al-pillared montmorillonite(Pr(S)/Mt)catalysts were prepared by impregnat...In this study,the perovskite nanocomposite PrFe_(x)Co_(1-x)O_(3)(Pr(S))was successfully synthesized by the sol-gel method;PrFe_(x)Co_(1-x)O_(3)/Al-pillared montmorillonite(Pr(S)/Mt)catalysts were prepared by impregnation(D)method and solid-melting(G)method,respectively,with Pr(S)as the active component and Al-pillared montmorillonite as the carrier.The catalysts were applied to treat the 2-hydroxybenzoic acid(2-HA)-simulated wastewater by catalytic wet peroxide oxidation(CWPO)technique,and the chemical oxygen demand(COD)removal rate and the 2-HA degradation rate were used as indicators to evaluate the catalytic performance.The results of the experiment indicated that the solid-melting method was more conducive to preparing the catalyst when the Co/Fe molar ratio of 7:3 and the optimal structural properties of the catalysts were achieved.The influence of operating parameters,including reaction temperature,catalyst dosage,H_(2)O_(2)dosage,pH,and initial 2-HA concentration,were optimized for the degradation of 2-HA by CWPO.The results showed that 97.64%of 2-HA degradation and 75.23%of COD removal rate were achieved under more suitable experimental conditions.In addition,after the catalyst was used five times,the degradation rate of 2-HA could still reach 76.93%,which implied the high stability and reusability of the catalyst.The high catalytic activity of the catalyst was due to the doping of Co into PrFeO_(3),which could promote the generation of HO·,and the high stability could be attributed to the loading of Pr(S)onto Al-Mt,which reduced the leaching of reactive metals.The study of reaction mechanism and kinetics showed that the whole degradation process conformed to the pseudo-firstorder kinetic equation,and the Langmuir-Hinshelwood method was applied to demonstrate that catalysis was dominant in the degradation process.展开更多
The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional meth...The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional method and presents an extended wet sieving method.The extended method uses both the steel sieves and the nylon filter cloth sieves.The apertures of the cloth sieves are smaller than 0.063 mm and equal 0.048 mm,0.038 mm,0.014 mm,0.012 mm,0.0063 mm,0.004 mm,0.003 mm,0.002 mm,and 0.001 mm,respectively.The extended method uses five steps to separate the general soil into many material sub-groups of gravel,sand,silt and clay with known particle size ranges.The complete PSD of the general soil is then calculated from the dry masses of the individual material sub-groups.The extended method is demonstrated with a general soil of completely decomposed granite(CDG)in Hong Kong,China.The silt and clay materials with different particle size ranges are further examined,checked and verified using stereomicroscopic observation,physical and chemical property tests.The results further confirm the correctness of the extended wet sieving method.展开更多
The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to...The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.展开更多
There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity sch...There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity scheme(IVD scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall(MPB-C scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes(MPB-W scheme)and the geometric formulation scheme(GF scheme).But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the past.In this paper,the numerical stability and accuracy of these schemes are clarified for the first time,by applying the five widely used contact angle schemes to simulate a two-dimensional(2D)sessile droplet on wall and capillary imbibition in a 2D channel as the examples of static wetting and dynamic wetting simulations respectively.(i)It is shown that the simulated contact angles by the GF scheme are consistent at different density ratios for the same prescribed contact angle,but the simulated contact angles by the PB scheme,IVD scheme,MPB-C scheme and MPB-W scheme change with density ratios for the same fluid-solid interaction strength.The PB scheme is found to be the most unstable scheme for simulating static wetting at increased density ratios.(ii)Although the spurious velocity increases with the increased liquid/vapor density ratio for all the contact angle schemes,the magnitude of the spurious velocity in the PB scheme,IVD scheme and GF scheme are smaller than that in the MPB-C scheme and MPB-W scheme.(iii)The fluid density variation near the wall in the PB scheme is the most significant,and the variation can be diminished in the IVD scheme,MPB-C scheme andMPBWscheme.The variation totally disappeared in the GF scheme.(iv)For the simulation of capillary imbibition,the MPB-C scheme,MPB-Wscheme and GF scheme simulate the dynamics of the liquid-vapor interface well,with the GF scheme being the most accurate.The accuracy of the IVD scheme is low at a small contact angle(44 degrees)but gets high at a large contact angle(60 degrees).However,the PB scheme is the most inaccurate in simulating the dynamics of the liquid-vapor interface.As a whole,it is most suggested to apply the GF scheme to simulate static wetting or dynamic wetting,while it is the least suggested to use the PB scheme to simulate static wetting or dynamic wetting.展开更多
Heat events may be humid or dry.While several indices incorporate humidity,such combined indices obscure identification and exploration of heat events by their different humidity characteristics.The new HadISDH.extrem...Heat events may be humid or dry.While several indices incorporate humidity,such combined indices obscure identification and exploration of heat events by their different humidity characteristics.The new HadISDH.extremes global gridded monitoring product uniquely provides a range of wet and dry bulb temperature extremes indices.Analysis of this new data product demonstrates its value as a tool for quantifying exposure to humid verses dry heat events.It also enables exploration into“stealth heat events”,where humidity is high,perhaps enough to affect productivity and health,while temperature remains moderate.Such events may not typically be identified as“heat events”by temperature-focused heat indices.Over 1973-2022,the peak magnitude of humid extremes(maximum daily wet bulb temperature over a month;T_(w)X)for the global annual mean increased significantly at 0.13±0.04℃(10 yr)^(−1),which is slightly slower than the global annual mean T_(w) increase of 0.22±0.04℃(10 yr)^(−1).The frequency of moderate humid extreme events per year(90th per-centile daily maxima wet bulb temperature exceedance;T_(w)X90p)also increased significantly at 4.61±1.07 d yr^(−1)(10 yr)^(−1).These rates were slower than for temperature extremes,TX and TX90p,which respectively increased significantly at 0.27±0.04℃(10 yr)^(−1) and 5.53±0.72 d yr^(−1)(10 yr)^(−1).Similarly,for the UK/Europe focus region,JJA-mean T_(w)X increased significantly,again at a slower rate than for TX and mean T_(w).HadISDH.extremes shows some evidence of“stealth heat events”occurring where humidity is high but temperature remains more moderate.展开更多
HadISDH.extremes is an annually updated global gridded monthly monitoring product of wet and dry bulb temperature–based extremes indices,from January 1973 to December 2022.Data quality,including spatial and temporal ...HadISDH.extremes is an annually updated global gridded monthly monitoring product of wet and dry bulb temperature–based extremes indices,from January 1973 to December 2022.Data quality,including spatial and temporal stability,is a key focus.The hourly data are quality controlled.Homogeneity is assessed on monthly means and used to score each gridbox according to its homogeneity rather than to apply adjustments.This enables user-specific screening for temporal stability and avoids errors from inferring adjustments from monthly means for the daily maximum values.For general use,a score(HQ Flag)of 0 to 6 is recommended.A range of indices are presented,aligning with existing standardised indices.Uniquely,provision of both wet and dry bulb indices allows exploration of heat event character—whether it is a“humid and hot”,“dry and hot”or“humid and warm”event.It is designed for analysis of long-term trends in regional features.HadISDH.extremes can be used to study local events,but given the greater vulnerability to errors of maximum compared to mean values,cross-validation with independent information is advised.展开更多
The wide engineered application of compacted expansive soils necessitates understanding their behavior under field conditions.The results of this study demonstrate how seasonal climatic variation and stress and bounda...The wide engineered application of compacted expansive soils necessitates understanding their behavior under field conditions.The results of this study demonstrate how seasonal climatic variation and stress and boundary conditions individually or collectively influence the hydraulic and volume change behavior of compacted highly expansive soils.The cyclic wetting and drying(CWD)process was applied for two boundary conditions,i.e.constant stress(CS)and constant volume(CV),and for a wide range of axial stress states.The adopted CWD process affected the hydraulic and volume change behaviors of expansive soils,with the first cycle of wetting and drying being the most effective.The CWD process under CS conditions resulted in shrinkage accumulation and reduction in saturated hydraulic conductivity(k sat).On the other hand,CWD under CV conditions caused a reduction of swell pressure while has almost no impact on k sat.An elastic response to CWD was achieved after the third cycle for saturated hydraulic conductivity(k sat),the third to fourth cycle for the volume change potential under the CV conditions,and the fourth to fifth cycle for the volume change potential under the CS conditions.Finally,both swell pressure(s s)and saturated hydraulic conductivity(k sat)are not fundamental parameters of the expansive soil but rather depend on stress,boundary and wetting conditions.展开更多
Alternate wetting and drying(AWD)system,in which water has been reduced by approximately 35%with an increased occurrence of beneficial arbuscular mycorrhizal(AM)symbiosis and no negative impact on rice yield,was propo...Alternate wetting and drying(AWD)system,in which water has been reduced by approximately 35%with an increased occurrence of beneficial arbuscular mycorrhizal(AM)symbiosis and no negative impact on rice yield,was proposed to utilize water and nutrients more sustainable.In this study,we selected six rice cultivars(Centauro,Loto,Selenio,Vialone nano,JSendra and Puntal)grown under AWD conditions,and investigated their responsiveness to AM colonization and how they select diverse AM taxa.In order to investigate root-associated AM fungus communities,molecular cloning-Sanger sequencing on small subunit rDNA data were obtained from five out of the six rice cultivars and compared with Next Generation Sequencing(NGS)data,which were previously obtained in Vialone nano.The results showed that all the cultivars were responsive to AM colonization with the development of AM symbiotic structures,even if with differences in the colonization and arbuscule abundance in the root systems.We identified 16 virtual taxa(VT)in the soil compartment and 7 VT in the root apparatus.We emphasized that the NGS analysis gives additional value to the results thanks to a more in-depth reading of the less represented AM fungus taxa.展开更多
There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in cata...There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.展开更多
Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of ...Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical behavior.In this review paper,methods that are commonly used to study soil microstructure are summarized.Among them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)technology.Moreover,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several decades.Soils compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal PSD.During drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate pores.During wetting,both the intra-and inter-aggregate pores increase gradually in number and sizes.Changes in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to wetting.During wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from macro-pores.Furthermore,based on this analysis and identified research needs,some important areas of research focus are proposed for future work.These areas include innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.展开更多
MXenes are a class of 2D nanomaterials with exceptional tailormade properties such as mechano-ceramic nature,rich chemistry,and hydrophilicity,to name a few.However,one of the most challenging issues in any composite/...MXenes are a class of 2D nanomaterials with exceptional tailormade properties such as mechano-ceramic nature,rich chemistry,and hydrophilicity,to name a few.However,one of the most challenging issues in any composite/hybrid system is the interfacial wetting.Having a superior integrity of a given composite system is a direct consequence of the proper wettability.While wetting is a fundamental feature,dictating many physical and chemical attributes,most of the common nanomaterials possesses poor affinity due to hydrophobic nature,making them hard to be easily dispersed in a given composite.Thanks to low contact angle,MXenes can offer themselves as an ideal candidate for manufacturing different nano-hybrid structures.Herein this review,it is aimed to particularly study the wettability of MXenes.In terms of the layout of the present study,MXenes are first briefly introduced,and then,the wettability phenomenon is discussed in detail.Upon reviewing the sporadic research efforts conducted to date,a particular attention is paid on the current challenges and research pitfalls to light up the future perspectives.It is strongly believed that taking the advantage of MXene’s rich hydrophilic surface may have a revolutionizing role in the fabrication of advanced materials with exceptional features.展开更多
Permeability is a key parameter for coalbed methane development.Although the absolute permeability of coal has been extensively studied,wettability and pore structure properties continue to challenge the microscopic d...Permeability is a key parameter for coalbed methane development.Although the absolute permeability of coal has been extensively studied,wettability and pore structure properties continue to challenge the microscopic description of water-gas flow in coal.For this purpose,we reconstructed the microstructures of low-rank coal using micro-computed tomography(micro-CT)images.Pore geometry and pore-throat parameters are introduced to establish a relationship with absolute permeability.A dual-porosity pore network model is developed to study water-gas displacement under different wetting and pore structure properties.Results show that absolute permeability is significantly affected by pore geometry and can be described using a binary quadratic function of porosity and fractal dimension.Water-gas relative permeability varies significantly and the residual gas saturation is lower;the crossover saturation first decreased and then increased with increasing porosity under hydrophobic conditions.While the water relative permeability is lower and a certain amount of gas is trapped in complex pore-throat networks;the crossover saturation is higher under hydrophilic conditions.Models with large percolating porosity and well-developed pore networks have high displacement efficiency due to low capillary resistance and avoidance of trapping.This work provides a systematic description of absolute permeability and water-gas relative permeability in coal microstructure for enhanced gas recovery.展开更多
Surface tension plays a central role in the mechanical behavior of soft materials such as gels.Elastocapillary deformation of elastic graded substrates is ubiquitous in soft materials.In this work,the effect of a part...Surface tension plays a central role in the mechanical behavior of soft materials such as gels.Elastocapillary deformation of elastic graded substrates is ubiquitous in soft materials.In this work,the effect of a partially wetting sessile liquid droplet on the elastocapillary deformation of a soft elastic graded substrate is studied.The modulus is assumed to have an exponential form along the thickness direction.By applying the Fourier transformation,a mixed boundary-value problem is reduced into a dual integral equation.The numerical results show that the surface displacement is strongly affected by the inhomogeneity of the material.The study of the wetting properties of gel substrates is essential for both understanding the wetting phenomena of gels and developing gels for applications as soft actuators and sensors that can be used in wearable electronics and soft robotics.展开更多
The development of solid waste resources as constituent materials for wet shotcrete has significant economic and environmental advantages. In this study, the concept of using tailings as aggregate and fly ash and slag...The development of solid waste resources as constituent materials for wet shotcrete has significant economic and environmental advantages. In this study, the concept of using tailings as aggregate and fly ash and slag powder as auxiliary cementitious material is proposed and experiments are carried out by response surface methodology(RSM). Multivariate nonlinear response models are constructed to investigate the effect of factors on the uniaxial compressive strength(UCS) of tailings wet shotcrete(TWSC). The UCS of TWSC is predicted and optimized by constructing Gaussian process regression(GPR) and genetic algorithm(GA). The UCS of TWSC is gradually enhanced with the increase of slag powder dosage and fineness modulus, and it is enhanced first and then decreased with the increase of fly ash dosage. The microstructure of TWSC has the highest gray value and the highest UCS when the fly ash dosage is about 120 kg·m^(-3). The GPR–GA model constructed in this study achieves high accuracy prediction and optimization of the UCS of TWSC under multi-factor conditions.展开更多
A moving trapezoidal profiled convective-radiative porous longitudinal fin wetted in a single-phase fluid is considered in the current article.The periodic variation in the fin base temperature is taken into account a...A moving trapezoidal profiled convective-radiative porous longitudinal fin wetted in a single-phase fluid is considered in the current article.The periodic variation in the fin base temperature is taken into account along with the temperature sensitive thermal conductivity and convective heat transfer coefficients.The modeled problem,which is resolved into a non-linear partial differential equation(PDE),is made dimensionless and solved by employing the finite difference method(FDM).The results are displayed through graphs and discussed.The effects of amplitude,frequency of oscillation,wet nature,Peclet number,and other relevant quantities on the distribution of temperature through the fin length and with the dimensionless time are investigated.It is deciphered that the periodic heat transfer gives rise to the wavy nature of the fin thermal profile against time.The analysis is beneficial in the design of fin structures for applications like solar collectors,space/airborne applications,and refrigeration industries.展开更多
Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often...Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often proves challenging.In this study,repeated non-oxidative acid etching of ore samples from Shuiyindong gold deposit was applied to enable elemental depth profiling of goldbearing arsenian pyrite grains.ICP-OES and AAS were used to determine the dissolved Fe,As,and Au concentrations in each of the etching solutions,and XPS was carried out to exam the etched mineral surfaces.In contrast to conventional ion beam etching that may cause substantial sample damage,our acid etching method does not seem to significantly alter the composition and chemical state of the samples.The etched depths directly converted from the measured elemental concentrations can reproducibly reach a very high resolution of~1 nm,and can be conveniently controlled through varying the etching time.While the Fe and As depth profiles consistently reflect the surface oxidation property of arsenian pyrite,the Au profile displaying an obvious upward trend reveals the ore fluid evolution at the late stage of mineralization.Based on our experimental results,we demonstrate that our wet chemistry method is capable of effective depth profiling of gold ore and perhaps other geological samples,with advantages surpassing many instrumental techniques including negligible sample damage,nanoscale resolution as well as isotropic etching.展开更多
基金supported by the National key research and development program (2019YFA0607104)National Natural Science Foundation of China (Grant Nos. 41991231, 42275034, 41975076, 42075029, 42075017, and 42075018)the Gansu Provincial Science and Technology Project (22JR5RA405)。
文摘As an important factor that directly affects agricultural production, the social economy, and policy implementation,observed changes in dry/wet conditions have become a matter of widespread concern. However, previous research has mainly focused on the long-term linear changes of dry/wet conditions, while the detection and evolution of the non-linear trends related to dry/wet changes have received less attention. The non-linear trends of the annual aridity index, obtained by the Ensemble Empirical Mode Decomposition(EEMD) method, reveal that changes in dry/wet conditions in China are asymmetric and can be characterized by contrasting features in both time and space in China. Spatially, most areas in western China have experienced transitions from drying to wetting, while opposite changes have occurred in most areas of eastern China. Temporally, the transitions occurred earlier in western China compared to eastern China. Research into the asymmetric spatial characteristics of dry/wet conditions compensates for the inadequacies of previous studies, which focused solely on temporal evolution;at the same time, it remedies the inadequacies of traditional research on linear trends over centennial timescales. Analyzing the non-linear trend also provides for a more comprehensive understanding of the drying/wetting changes in China.
基金This work was supported by the National Natural Science Foundation of China(32071943,32272198).
文摘Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breeding and cultivation to improve nutritional quality.However,little information is available on differences in lysine anabolism between SG and IG and the underlying mechanism,and whether and how irrigation regimes affect lysine anabolism in these grains.A japonica rice cultivar was grown in the field and two irrigation regimes,continuous flooding(CF)and wetting alternating with partial drying(WAPD),were imposed from heading to the mature stage.Lysine content and activities of key enzymes of lysine biosynthesis,and levels of brassinosteroids(BRs)were lower in the IG than in the SG at the early grainfilling stage but higher at middle and late grain-filling stages.WAPD increased activities of these key enzymes,BR levels,and contents of lysine and total amino acids in IG,but not SG relative to CF.Application of 2,4-epibrassinolide to rice panicles in CF during early grain filling reproduced the effects of WAPD,but neither treatment altered the activities of enzymes responsible for lysine catabolism in either SG or IG.WAPD and elevated BR levels during grain filling increased lysine biosynthesis in IG.Improvement in lysine biosynthesis in rice should focus on IG.
基金supported by the Key Research and Development Program of Shaanxi,China(2018GY-067).
文摘In this study,the perovskite nanocomposite PrFe_(x)Co_(1-x)O_(3)(Pr(S))was successfully synthesized by the sol-gel method;PrFe_(x)Co_(1-x)O_(3)/Al-pillared montmorillonite(Pr(S)/Mt)catalysts were prepared by impregnation(D)method and solid-melting(G)method,respectively,with Pr(S)as the active component and Al-pillared montmorillonite as the carrier.The catalysts were applied to treat the 2-hydroxybenzoic acid(2-HA)-simulated wastewater by catalytic wet peroxide oxidation(CWPO)technique,and the chemical oxygen demand(COD)removal rate and the 2-HA degradation rate were used as indicators to evaluate the catalytic performance.The results of the experiment indicated that the solid-melting method was more conducive to preparing the catalyst when the Co/Fe molar ratio of 7:3 and the optimal structural properties of the catalysts were achieved.The influence of operating parameters,including reaction temperature,catalyst dosage,H_(2)O_(2)dosage,pH,and initial 2-HA concentration,were optimized for the degradation of 2-HA by CWPO.The results showed that 97.64%of 2-HA degradation and 75.23%of COD removal rate were achieved under more suitable experimental conditions.In addition,after the catalyst was used five times,the degradation rate of 2-HA could still reach 76.93%,which implied the high stability and reusability of the catalyst.The high catalytic activity of the catalyst was due to the doping of Co into PrFeO_(3),which could promote the generation of HO·,and the high stability could be attributed to the loading of Pr(S)onto Al-Mt,which reduced the leaching of reactive metals.The study of reaction mechanism and kinetics showed that the whole degradation process conformed to the pseudo-firstorder kinetic equation,and the Langmuir-Hinshelwood method was applied to demonstrate that catalysis was dominant in the degradation process.
基金The work described in this paper was partially supported by grants from the Research Grant Council of the Hong Kong Special Administrative Region,China(Project Nos.HKU 17207518 and R5037-18).
文摘The traditional standard wet sieving method uses steel sieves with aperture?0.063 mm and can only determine the particle size distribution(PSD)of gravel and sand in general soil.This paper extends the traditional method and presents an extended wet sieving method.The extended method uses both the steel sieves and the nylon filter cloth sieves.The apertures of the cloth sieves are smaller than 0.063 mm and equal 0.048 mm,0.038 mm,0.014 mm,0.012 mm,0.0063 mm,0.004 mm,0.003 mm,0.002 mm,and 0.001 mm,respectively.The extended method uses five steps to separate the general soil into many material sub-groups of gravel,sand,silt and clay with known particle size ranges.The complete PSD of the general soil is then calculated from the dry masses of the individual material sub-groups.The extended method is demonstrated with a general soil of completely decomposed granite(CDG)in Hong Kong,China.The silt and clay materials with different particle size ranges are further examined,checked and verified using stereomicroscopic observation,physical and chemical property tests.The results further confirm the correctness of the extended wet sieving method.
文摘The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.
基金sponsored by the National Natural Science Foundation of China under Grant No.52206101Shanghai Sailing Program under Grant No.20YF1431200the Experiments for Space Exploration Program and the Qian Xuesen Laboratory,China Academy of Space Technology under Grant No.TKTSPY-2020-01-01.
文摘There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity scheme(IVD scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall(MPB-C scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes(MPB-W scheme)and the geometric formulation scheme(GF scheme).But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the past.In this paper,the numerical stability and accuracy of these schemes are clarified for the first time,by applying the five widely used contact angle schemes to simulate a two-dimensional(2D)sessile droplet on wall and capillary imbibition in a 2D channel as the examples of static wetting and dynamic wetting simulations respectively.(i)It is shown that the simulated contact angles by the GF scheme are consistent at different density ratios for the same prescribed contact angle,but the simulated contact angles by the PB scheme,IVD scheme,MPB-C scheme and MPB-W scheme change with density ratios for the same fluid-solid interaction strength.The PB scheme is found to be the most unstable scheme for simulating static wetting at increased density ratios.(ii)Although the spurious velocity increases with the increased liquid/vapor density ratio for all the contact angle schemes,the magnitude of the spurious velocity in the PB scheme,IVD scheme and GF scheme are smaller than that in the MPB-C scheme and MPB-W scheme.(iii)The fluid density variation near the wall in the PB scheme is the most significant,and the variation can be diminished in the IVD scheme,MPB-C scheme andMPBWscheme.The variation totally disappeared in the GF scheme.(iv)For the simulation of capillary imbibition,the MPB-C scheme,MPB-Wscheme and GF scheme simulate the dynamics of the liquid-vapor interface well,with the GF scheme being the most accurate.The accuracy of the IVD scheme is low at a small contact angle(44 degrees)but gets high at a large contact angle(60 degrees).However,the PB scheme is the most inaccurate in simulating the dynamics of the liquid-vapor interface.As a whole,it is most suggested to apply the GF scheme to simulate static wetting or dynamic wetting,while it is the least suggested to use the PB scheme to simulate static wetting or dynamic wetting.
基金supported by the UK–China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund
文摘Heat events may be humid or dry.While several indices incorporate humidity,such combined indices obscure identification and exploration of heat events by their different humidity characteristics.The new HadISDH.extremes global gridded monitoring product uniquely provides a range of wet and dry bulb temperature extremes indices.Analysis of this new data product demonstrates its value as a tool for quantifying exposure to humid verses dry heat events.It also enables exploration into“stealth heat events”,where humidity is high,perhaps enough to affect productivity and health,while temperature remains moderate.Such events may not typically be identified as“heat events”by temperature-focused heat indices.Over 1973-2022,the peak magnitude of humid extremes(maximum daily wet bulb temperature over a month;T_(w)X)for the global annual mean increased significantly at 0.13±0.04℃(10 yr)^(−1),which is slightly slower than the global annual mean T_(w) increase of 0.22±0.04℃(10 yr)^(−1).The frequency of moderate humid extreme events per year(90th per-centile daily maxima wet bulb temperature exceedance;T_(w)X90p)also increased significantly at 4.61±1.07 d yr^(−1)(10 yr)^(−1).These rates were slower than for temperature extremes,TX and TX90p,which respectively increased significantly at 0.27±0.04℃(10 yr)^(−1) and 5.53±0.72 d yr^(−1)(10 yr)^(−1).Similarly,for the UK/Europe focus region,JJA-mean T_(w)X increased significantly,again at a slower rate than for TX and mean T_(w).HadISDH.extremes shows some evidence of“stealth heat events”occurring where humidity is high but temperature remains more moderate.
基金supported by the UK–China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund
文摘HadISDH.extremes is an annually updated global gridded monthly monitoring product of wet and dry bulb temperature–based extremes indices,from January 1973 to December 2022.Data quality,including spatial and temporal stability,is a key focus.The hourly data are quality controlled.Homogeneity is assessed on monthly means and used to score each gridbox according to its homogeneity rather than to apply adjustments.This enables user-specific screening for temporal stability and avoids errors from inferring adjustments from monthly means for the daily maximum values.For general use,a score(HQ Flag)of 0 to 6 is recommended.A range of indices are presented,aligning with existing standardised indices.Uniquely,provision of both wet and dry bulb indices allows exploration of heat event character—whether it is a“humid and hot”,“dry and hot”or“humid and warm”event.It is designed for analysis of long-term trends in regional features.HadISDH.extremes can be used to study local events,but given the greater vulnerability to errors of maximum compared to mean values,cross-validation with independent information is advised.
文摘The wide engineered application of compacted expansive soils necessitates understanding their behavior under field conditions.The results of this study demonstrate how seasonal climatic variation and stress and boundary conditions individually or collectively influence the hydraulic and volume change behavior of compacted highly expansive soils.The cyclic wetting and drying(CWD)process was applied for two boundary conditions,i.e.constant stress(CS)and constant volume(CV),and for a wide range of axial stress states.The adopted CWD process affected the hydraulic and volume change behaviors of expansive soils,with the first cycle of wetting and drying being the most effective.The CWD process under CS conditions resulted in shrinkage accumulation and reduction in saturated hydraulic conductivity(k sat).On the other hand,CWD under CV conditions caused a reduction of swell pressure while has almost no impact on k sat.An elastic response to CWD was achieved after the third cycle for saturated hydraulic conductivity(k sat),the third to fourth cycle for the volume change potential under the CV conditions,and the fourth to fifth cycle for the volume change potential under the CS conditions.Finally,both swell pressure(s s)and saturated hydraulic conductivity(k sat)are not fundamental parameters of the expansive soil but rather depend on stress,boundary and wetting conditions.
基金AGER-Fondazioni in rete per la ricerca agroalimentare(https://www.progettoager.it/)(Grant No.2010-2369)by Joint Programming Initiative on Agriculture,Food Security and Climate Change(FACCE-JPI)project Green Rice(Sustainable and environmental friendly rice cultivation systems in Europe).
文摘Alternate wetting and drying(AWD)system,in which water has been reduced by approximately 35%with an increased occurrence of beneficial arbuscular mycorrhizal(AM)symbiosis and no negative impact on rice yield,was proposed to utilize water and nutrients more sustainable.In this study,we selected six rice cultivars(Centauro,Loto,Selenio,Vialone nano,JSendra and Puntal)grown under AWD conditions,and investigated their responsiveness to AM colonization and how they select diverse AM taxa.In order to investigate root-associated AM fungus communities,molecular cloning-Sanger sequencing on small subunit rDNA data were obtained from five out of the six rice cultivars and compared with Next Generation Sequencing(NGS)data,which were previously obtained in Vialone nano.The results showed that all the cultivars were responsive to AM colonization with the development of AM symbiotic structures,even if with differences in the colonization and arbuscule abundance in the root systems.We identified 16 virtual taxa(VT)in the soil compartment and 7 VT in the root apparatus.We emphasized that the NGS analysis gives additional value to the results thanks to a more in-depth reading of the less represented AM fungus taxa.
基金supported by National Natural Science Foundation of China(52100072,52100213)the Fundamental Research FundsfortheCentralUniversities(JZ2021HGTA0159,JZ2021HGQA0212)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21021101)the Scientific Research Common Program of Beijing Municipal Commission of Education(KM202010017006)the Beijing Natural Science Foundation(8214056)。
文摘There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.
基金This work was supported by National Natural Science Founda-tion of China(Grant Nos.41925012 and 41902271)Natural Science Foundation of Jiangsu Province(Grant No.BK20211087).
文摘Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical behavior.In this review paper,methods that are commonly used to study soil microstructure are summarized.Among them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)technology.Moreover,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several decades.Soils compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal PSD.During drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate pores.During wetting,both the intra-and inter-aggregate pores increase gradually in number and sizes.Changes in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to wetting.During wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from macro-pores.Furthermore,based on this analysis and identified research needs,some important areas of research focus are proposed for future work.These areas include innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.
文摘MXenes are a class of 2D nanomaterials with exceptional tailormade properties such as mechano-ceramic nature,rich chemistry,and hydrophilicity,to name a few.However,one of the most challenging issues in any composite/hybrid system is the interfacial wetting.Having a superior integrity of a given composite system is a direct consequence of the proper wettability.While wetting is a fundamental feature,dictating many physical and chemical attributes,most of the common nanomaterials possesses poor affinity due to hydrophobic nature,making them hard to be easily dispersed in a given composite.Thanks to low contact angle,MXenes can offer themselves as an ideal candidate for manufacturing different nano-hybrid structures.Herein this review,it is aimed to particularly study the wettability of MXenes.In terms of the layout of the present study,MXenes are first briefly introduced,and then,the wettability phenomenon is discussed in detail.Upon reviewing the sporadic research efforts conducted to date,a particular attention is paid on the current challenges and research pitfalls to light up the future perspectives.It is strongly believed that taking the advantage of MXene’s rich hydrophilic surface may have a revolutionizing role in the fabrication of advanced materials with exceptional features.
基金the National Natural Science Foundation of China(Nos.51934004,51974176)the Natural Science Foundation for Distinguished Young Scholars of Shandong Province(No.ZR2020JQ22)+1 种基金the Youth Science and Technology Innovation of Shandong Province(No.2019KJH006)the Special Funds for Taishan Scholar Project(No.TS20190935).
文摘Permeability is a key parameter for coalbed methane development.Although the absolute permeability of coal has been extensively studied,wettability and pore structure properties continue to challenge the microscopic description of water-gas flow in coal.For this purpose,we reconstructed the microstructures of low-rank coal using micro-computed tomography(micro-CT)images.Pore geometry and pore-throat parameters are introduced to establish a relationship with absolute permeability.A dual-porosity pore network model is developed to study water-gas displacement under different wetting and pore structure properties.Results show that absolute permeability is significantly affected by pore geometry and can be described using a binary quadratic function of porosity and fractal dimension.Water-gas relative permeability varies significantly and the residual gas saturation is lower;the crossover saturation first decreased and then increased with increasing porosity under hydrophobic conditions.While the water relative permeability is lower and a certain amount of gas is trapped in complex pore-throat networks;the crossover saturation is higher under hydrophilic conditions.Models with large percolating porosity and well-developed pore networks have high displacement efficiency due to low capillary resistance and avoidance of trapping.This work provides a systematic description of absolute permeability and water-gas relative permeability in coal microstructure for enhanced gas recovery.
基金supported by the National Natural Science Foundation of China(Nos.12272195,12272269 and 12262033)。
文摘Surface tension plays a central role in the mechanical behavior of soft materials such as gels.Elastocapillary deformation of elastic graded substrates is ubiquitous in soft materials.In this work,the effect of a partially wetting sessile liquid droplet on the elastocapillary deformation of a soft elastic graded substrate is studied.The modulus is assumed to have an exponential form along the thickness direction.By applying the Fourier transformation,a mixed boundary-value problem is reduced into a dual integral equation.The numerical results show that the surface displacement is strongly affected by the inhomogeneity of the material.The study of the wetting properties of gel substrates is essential for both understanding the wetting phenomena of gels and developing gels for applications as soft actuators and sensors that can be used in wearable electronics and soft robotics.
基金financially supported by the National Key Research and Development Program of China (Nos.2018YFC1900603 and 2018YFC0604604)。
文摘The development of solid waste resources as constituent materials for wet shotcrete has significant economic and environmental advantages. In this study, the concept of using tailings as aggregate and fly ash and slag powder as auxiliary cementitious material is proposed and experiments are carried out by response surface methodology(RSM). Multivariate nonlinear response models are constructed to investigate the effect of factors on the uniaxial compressive strength(UCS) of tailings wet shotcrete(TWSC). The UCS of TWSC is predicted and optimized by constructing Gaussian process regression(GPR) and genetic algorithm(GA). The UCS of TWSC is gradually enhanced with the increase of slag powder dosage and fineness modulus, and it is enhanced first and then decreased with the increase of fly ash dosage. The microstructure of TWSC has the highest gray value and the highest UCS when the fly ash dosage is about 120 kg·m^(-3). The GPR–GA model constructed in this study achieves high accuracy prediction and optimization of the UCS of TWSC under multi-factor conditions.
基金Department of Science and Technology,Govt of India for their support under the DST-FIST Programme for HEIs(No.SR/FST/MS-I/2018/23(C))the University Grants Commission,New Delhi,India(No.CSIR-UGC NET DEC.2019)/(Student ID:191620111468)for the financial support in the form of UGC-Junior Research Fellowship。
文摘A moving trapezoidal profiled convective-radiative porous longitudinal fin wetted in a single-phase fluid is considered in the current article.The periodic variation in the fin base temperature is taken into account along with the temperature sensitive thermal conductivity and convective heat transfer coefficients.The modeled problem,which is resolved into a non-linear partial differential equation(PDE),is made dimensionless and solved by employing the finite difference method(FDM).The results are displayed through graphs and discussed.The effects of amplitude,frequency of oscillation,wet nature,Peclet number,and other relevant quantities on the distribution of temperature through the fin length and with the dimensionless time are investigated.It is deciphered that the periodic heat transfer gives rise to the wavy nature of the fin thermal profile against time.The analysis is beneficial in the design of fin structures for applications like solar collectors,space/airborne applications,and refrigeration industries.
基金Financial supports from the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the National Natural Science Foundation of China(41872046,41902041 and 41173074)the Natural Science Research Project of Education Department of Guizhou Province(No.KY[2018]004)are sincerely acknowledged.
文摘Enrichment of As and Au at the overgrowth rims of arsenian pyrite is a distinctive feature of Carlin-type gold ores.Revealing distribution of such key elements in high resolution is of fundamental importance yet often proves challenging.In this study,repeated non-oxidative acid etching of ore samples from Shuiyindong gold deposit was applied to enable elemental depth profiling of goldbearing arsenian pyrite grains.ICP-OES and AAS were used to determine the dissolved Fe,As,and Au concentrations in each of the etching solutions,and XPS was carried out to exam the etched mineral surfaces.In contrast to conventional ion beam etching that may cause substantial sample damage,our acid etching method does not seem to significantly alter the composition and chemical state of the samples.The etched depths directly converted from the measured elemental concentrations can reproducibly reach a very high resolution of~1 nm,and can be conveniently controlled through varying the etching time.While the Fe and As depth profiles consistently reflect the surface oxidation property of arsenian pyrite,the Au profile displaying an obvious upward trend reveals the ore fluid evolution at the late stage of mineralization.Based on our experimental results,we demonstrate that our wet chemistry method is capable of effective depth profiling of gold ore and perhaps other geological samples,with advantages surpassing many instrumental techniques including negligible sample damage,nanoscale resolution as well as isotropic etching.
