The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution...The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.展开更多
In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting conse...In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.展开更多
This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setti...This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setting time of polyurethane was further investigated using molecular dynamics simulations.Fourier transform infrared spectroscopy was also employed to systematically study the physical and chemical interactions between phosphate esters and polyurethane materials.The results demonstrate that a 1%concentration of phosphate ester provides the most effective retarding effect with minimal impact on the strength of polyurethane.When phosphate ester is added to the B component of the two-component polyurethane system,its interaction energy with component A decreases,as do the diffusion coefficient and aggregation degree of component B on the surface of component A.This reduction in interaction slows the setting time.Additionally,the addition of phosphate ester to polyurethane leads to the disappearance or weakening of functional groups,indicating competitive interactions within the phosphate ester components that inhibit the reaction rate.展开更多
Herein,a series of manganese oxide catalysts with different valences(Mn_(3)O_(4),Mn_(2)O_(3),and MnO_(2))were designed and synthesized for the synthesis of ethylene urea(EU)from ethylenediamine(EDA)and carbon dioxide(...Herein,a series of manganese oxide catalysts with different valences(Mn_(3)O_(4),Mn_(2)O_(3),and MnO_(2))were designed and synthesized for the synthesis of ethylene urea(EU)from ethylenediamine(EDA)and carbon dioxide(CO_(2)).With a maximal EDA conversion of 82%and EU selectivity of 99%at 160℃ for 2 h,Mn_(2)O_(3) catalysts had the best catalytic activity among them,which was superior to the reported catalysts.In the following order:Mn_(2)O_(3)>MnO_(2)>Mn_(3)O_(4),the catalytic activity for the synthesis of EU from CO_(2) and EDA decreased.Further characterization showed the Mn_(2)O_(3) catalyst possessed a greater Mn^(3+)/Mn4+ratio and more surface oxygen vacancies than the MnO_(2) and Mn_(3)O_(4),which improved its capacity to adsorb and activate CO_(2) and EDA.After four recycling runs,the EDA conversion slightly declined from 82%to 56%on Mn_(2)O_(3) catalyst,while no obvious change in EU selectivity was observed.The loss of surface Ov contents and Mn^(3+)proportion were concluded as main reasons for the decrease in catalytic activity over Mn_(2)O_(3) catalyst.This work demonstrated a metal oxide catalyst that was efficient in producing EU from CO_(2) and EDA.展开更多
Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane mater...Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane material is convenient for engineering applications;however,the compressive behaviour and feasibility of sprayed polyurethane material as a compressible layer remain unclear.To address this gap,this study conducts uniaxial compression tests and scanning electron microscope(SEM)tests to investigate the compressive behaviour of the rigid foams fabricated from a self-developed polyurethane spray material.A peridynamics model for the composite lining with a polyurethane compressible layer is then established.After validating the proposed method by comparison with two tests,a parametric study is carried out to investigate the damage evolution of the composite lining with a polyurethane compressible layer under various combinations of large deformations and compressible layer parameters.The results indicate that the polyurethane compressible layer effectively reduces the radial deformation and damage index of the secondary lining while increasing the damage susceptibility of the primary lining.The thickness of the polyurethane compressible layer significantly influences the prevention effect of large deformation-induced damage to the secondary lining within the density range of 50e100 kg/m^(3).In accordance with the experimental and simulation results,a simple,yet reasonable and convenient approach for determining the key parameters of the polyurethane compressible layer is proposed,along with a classification scheme for the parameters of the polyurethane compressible layer.展开更多
Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the...Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.展开更多
Transformation of urea and glycerol to glycerol carbonate is an environmental friendly and economical process.Catalysts play an indispensable role in the process.Although many catalysts have been developed,the perform...Transformation of urea and glycerol to glycerol carbonate is an environmental friendly and economical process.Catalysts play an indispensable role in the process.Although many catalysts have been developed,the performance of the catalysts still cannot meet the needs of industrialization.In this paper,research progress of the homogeneous and heterogeneous catalysts of the reaction over the past 20 years were reviewed systematically.According to the types and active centers of catalysts,the catalysts were classified systematically and analyzed in detail.The typical reaction mechanisms were also summarized.The research and development direction of catalysts is made more explicit through systematic classification and mechanism analysis.The article reveals more novel catalysts have been designed and used for the reaction,such as mixed metal oxides with special structures,solid wastes and non-metallic materials.This work summarized the current state of research and prospected possible routes for design of novel catalysts.It is hoped that this review can provide some references for developing efficient catalysts.展开更多
The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea o...The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea oxidation reaction(UOR).Herein,we report the loosely porous CoOOH nano-architecture(CoOOH LPNAs)with hydrophilic surface and abundant oxygen vacancies(Ov)on carbon fiber paper(CFP)by electrochemical reconstruction of the CoP nanoneedles precursor.The resulting three-dimensional electrode exhibited an impressively low potential of 1.38 V at 1000 mA·cm^(−2) and excellent durability for UOR.Furthermore,when tested in an anion exchange membrane(AEM)electrolyzer,it required only 1.53 V at 1000 mA·cm^(−2) for industrial urea-assisted water splitting and operated stably for 100 h without degrada-tion.Experimental and theoretical investigations revealed that rich oxygen vacancies effectively modulate the electronic structure of the CoOOH while creating unique Co3-triangle sites with Co atoms close together.As a result,the adsorption and desorption processes of reactants and intermediates in UOR could be finely tuned,thereby significantly reducing ther-modynamic barriers.Additionally,the superhydrophilic self-supported nanoarray structure facilitated rapid gas bubble release,improving the overall efficiency of the reaction and preventing potential catalyst detachment caused by bubble accumulation,thereby improving both catalytic activity and stability at high current densities.展开更多
Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due t...Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.展开更多
Dear Editor,Environmental pollution from microplastics(MPs)has recently gained attention as a potential environmental hazard(Chia et al.,2021).Agricultural soils could contain more MPs than the ocean by 2050 because m...Dear Editor,Environmental pollution from microplastics(MPs)has recently gained attention as a potential environmental hazard(Chia et al.,2021).Agricultural soils could contain more MPs than the ocean by 2050 because more MPs enter the soil than the ocean(Nizzetto et al.,2016).The carbon(C)-C backbone of degradation-resistant MPs provides considerable stability in the soil,where they can remain for several decades(Iqbal et al.,2023).展开更多
In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utili...In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utilization of ethoxylated castor oil increases tensile strength of PU up to 2.75 times(from3.2 to 8.8MPa),compared to PU based on neat castor oil.The PU composites filed with birch flour,diatomite and their mixture were prepared using home-made dissolver with cutter-shaped attachment at the speed of 1500 min−1.The tensile strength of PU composites filled with birch flour increases up to two time at loading 5–30 wt.%.Application of combined birch flour/diatomite additives has similar effect.The tensile strength of PU composites based on one to one mixture of ethoxylated and neat castor oil and filled with birch flour or combined birch flour/diatomite additives increases sharply up to 16–17 fold(up to 18.1 MPa).The birch flour and diatomite wellsoaked polymer matrix.The main factor determining mechanical performance is the morphology of PU samples and composites.Formation of ordered lamella-like structure of amorphous phase of PU matrix leads to an increase in mechanical performance and glass transition temperatures.Formation of disordered unstructured soft phase of starting PU leads to a decline of these functional properties.展开更多
Aqueous sodium-ion batteries(ASIBs)have garnered significant attention as promising candidates for large-scale energy storage applications.This interest is primarily due to their abundant resource availability,environ...Aqueous sodium-ion batteries(ASIBs)have garnered significant attention as promising candidates for large-scale energy storage applications.This interest is primarily due to their abundant resource availability,environmental friendliness,cost-effectiveness,and high safety.However,their electrochemical performance is limited by the thermodynamic properties of water molecules,resulting in inadequate cycling stability and insufficient specific energy density.To address these challenges,this study developed a hydrogen-bond enhanced urea-glycerol eutectic electrolyte(UGE)to expand the electrochemical stability window(ESW)of the electrolyte and suppress corresponding side reactions.The eutectic component disrupts the original hydrogen bonding network in water,creating a new,enhanced network that reduces the activity of free water and forms a uniform,dense passivation layer on the anode.As a result,the optimized composition of UGE exhibits a broad ESW of up to 3 V(-1.44 to 1.6 V vs.Ag/AgCl).The Prussian blue(PB)/UGE/NaTi_(2)(PO_(4))_(3)@C full cell exhibits an exceptionally long lifespan of 10,000 cycles at 10 C.This study introduces a low-cost,ultra-long-life ASIB system,utilizing a green and economical eutectic electrolyte,which expands the use of eutectic electrolytes in aqueous batteries and opens a new research horizon for constructing efficient electrochemical energy storage and conversion.展开更多
Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agen...Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agents,functional dendritic polyurethanes with nano structure were successfully prepared by one-pot method.The single molecule size and surface morphology were characterized by dynamic light scattering,transmission electron microscopy and scanning electron microscopy,and the molecular size in the dry state was 11 to 18 nm.The prepared materials were used as the boron adsorbents,and the effects of pH,time,boron solution concentration and temperature on the adsorption were studied.The results showed that the capacity of adsorbed boron could reach 110-130 mg·g^(-1).Adsorption was a homogeneous monolayer adsorption controlled by chemisorption,and adsorption thermodynamics showed that was a spontaneous endothermic process.Adsorption behavior was best described by the pseudo-second-order kinetic model and the Langmuir isotherm.This study also showed that it was difficult for ortho/meta-hydroxyl groups to chelate with H_(3)BO_(3) and other polyborates,and the chelates mainly had good chelating properties with B(OH)_(4)^(-),and the chelates formed had large steric hindrance.At the same time,increasing the number of hydroxyl groups of functional monomers was beneficial to increase the adsorption capacity of materials.In addition,the cyclic adsorption/desorption experiments showed that DPUs have good cyclic stability.At the same time,the adsorption results of the original salt lake brine showed that other metal ions in the brine had little effect on the adsorption of boron,and the adsorption capacity was as high as52.93 mg·g^(-1),and the maximum adsorption capacity was obtained by Adams-Bohart model to58.80 mg·g^(-1).The outstanding selectivity and adsorption capacity of these materials have broad potential application,and are expected to be used for the efficient adsorption and removal in boroncontaining water bodies.展开更多
Background Previous studies have shown a relationship between elevated blood urea nitrogen(BUN)level and poor outcomes in several diseases,but data on the prognostic significance of postoperative BUN in elderly patien...Background Previous studies have shown a relationship between elevated blood urea nitrogen(BUN)level and poor outcomes in several diseases,but data on the prognostic significance of postoperative BUN in elderly patients undergoing valve replacement surgery(VRS)remained sparse.Methods BUN was measured immediately after VRS.A total of 3118 elderly patients were enrolled and divided into four groups according to the quartiles of postoperative BUN:Q1,<5.6 mmol/L;Q2,5.6-6.8 mmol/L;Q3,6.8-8.4 mmol/L and Q4,≥8.4 mmol/L.The associations of postoperative BUN with in-hospital and 1-year mortality were evaluated.Results The incidence of inhospital death(1.0%vs.3.3%vs.3.3%vs.8.4%,P<0.001)and major adverse clinical events(5.1%vs.7.8%vs.9.9%vs.19.1%,P<0.001)was significantly higher in patients with a high BUN level.BUN was independently associated with all-cause in-hospital mortality[odds ratio(OR):1.11,95%confidential interval(CI):1.07-1.16,P<0.001].The receiver operating characteristic(ROC)curve showed that BUN>9 mmol/L had a sensitivity of 48.4%and specificity of 81.8% for predicting in-hospital death[area under curve(AUC):0.705,95%CI:0.658-0.753,P<0.001].Kaplan-Meier survival curves showed that patients with BUN>9 mmol/L had a higher one-year mortality than those without(log-rank test:91.7,P<0.001).Multivariate analysis showed that BUN>9 mmol/L was an independent predictor for one-year mortality[hazard ratio(HR):1.67,95%CI:1.23-2.28,P=0.001].Conclusions This study provided strong evidence that increased postoperative BUN level was associated with poor prognosis in elderly patients undergoing VRS.展开更多
In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials w...In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials with excellent room-temperature hardness were obtained.Fine-tuning the selenonium content established a synergy between antibacterial performance and network dynamics,as evidenced by vitrimer-like rheological behavior at elevated temperatures.Consequently,the coatings exhibited outstanding reprocessability while maintaining high transparency and structural stability after prolonged saltwater exposure.These integrated features underscore the potential of the developed cationic PU coatings as robust,multifunctional materials for electronic device protection and marine antifouling,combining long-term transparency,recyclability,and antibacterial durability.展开更多
Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibit...Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,...Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,collagen and gold nanoparticles with random and aligned nanofiber morphologies.The nanoparticles were green-synthesized using saffron extract.Nanoparticle characterizations with UV-Vis.spectroscopy and DLS illustrated theoretical and hydrodynamic diameters of around 7 and 13 nm,respectively,having zeta potential of−37 mV.SEM and TEM micrographs showed the morphology and diameters of obtained nanofibers.Also,further characterization were done by ATR-FTIR,XRD and TGA investigations and degradation studies.Contact angle measurements showed hydrophilic nature of the scaffolds(59±0.6°for aligned PU/Col/Au50 nanofibers compared to 120±2.6°for random PU nanofibers).Mechanical testing demonstrated appropriate tensile properties of the scaffolds for cardiac tissue engineering(Young’s modulus:1.53±0.07 MPa for aligned PU/Col/Au50 nanofibers compared to 0.4±0.05 MPa for random PU nanofibers).Finally,alamar blue assay revealed proper survival of the cells of HUVEC cell line on the prepared scaffolds,where the highest percentages were observed for random and aligned PU/Col/Au50 nanofibers.According to the findings,the fabricated PU/Col/AuNPs nanofibrous scaffolds could be considered as potential cardiac patches.展开更多
As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important facto...As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important factor in retaining DON.However,the effect of urea on the retention of DON with different molecular weights by clay minerals is unknown.In this study,the retention of both low-molecular weight DON(LMWD)and high-molecular weight DON(HMWD)by clay minerals in the presence of urea was investigated.For this purpose,batch adsorption and soil column leaching experiments,characterization analysis(Fourier transform infrared spectroscopy X-ray diffraction,and X-ray photoelectron spectroscopy),and molecular dynamics simulations were carried out.Urea had a positive effect on the adsorption of LMWD,whereas a competitive effect existed for the adsorption of HMWD.The dominant interactions among DON,urea,and clay minerals included H-bonding,ligand exchange,and cation exchange.The urea was preferentially adsorbed on clay minerals and formed a complex,which provided more adsorption sites to LMWD and only a few to HMWD.The presence of urea increased the retention of LMWD and decreased the retention of HMWD in clay minerals.The retention capacity of LMWD increased by 6.9%–12.8%,while that of HMWD decreased by 6.7%–53.1%.These findings suggest that LMWD tended to be trapped in soils,while HMWD was prone to be leached into groundwater,which can be used to evaluate the leaching of DON from soil to groundwater.展开更多
基金financially supported by the Maoming Science and Technology Bureau(No.2022DZXHT007)。
文摘The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.
基金supported by the National Natural Science Foundation of China(Grant Nos.12221002,12102233)。
文摘In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.
基金Funded by the National Natural Science Foundation of China(No.52370128)the Fundamental Research Funds for the Central Universities(No.2572022AW54)。
文摘This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setting time of polyurethane was further investigated using molecular dynamics simulations.Fourier transform infrared spectroscopy was also employed to systematically study the physical and chemical interactions between phosphate esters and polyurethane materials.The results demonstrate that a 1%concentration of phosphate ester provides the most effective retarding effect with minimal impact on the strength of polyurethane.When phosphate ester is added to the B component of the two-component polyurethane system,its interaction energy with component A decreases,as do the diffusion coefficient and aggregation degree of component B on the surface of component A.This reduction in interaction slows the setting time.Additionally,the addition of phosphate ester to polyurethane leads to the disappearance or weakening of functional groups,indicating competitive interactions within the phosphate ester components that inhibit the reaction rate.
基金supported by the National Natural Science Foundation of China(No.22278041)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(No.2022-K78)+1 种基金Jiangsu Province Key Laboratory of Fine Petrochemical Engineering(No.KF2107)the Advanced Catalysis and Green Manufacturing Collab-orative Innovation Center(No.ACGM2022-10-07)。
文摘Herein,a series of manganese oxide catalysts with different valences(Mn_(3)O_(4),Mn_(2)O_(3),and MnO_(2))were designed and synthesized for the synthesis of ethylene urea(EU)from ethylenediamine(EDA)and carbon dioxide(CO_(2)).With a maximal EDA conversion of 82%and EU selectivity of 99%at 160℃ for 2 h,Mn_(2)O_(3) catalysts had the best catalytic activity among them,which was superior to the reported catalysts.In the following order:Mn_(2)O_(3)>MnO_(2)>Mn_(3)O_(4),the catalytic activity for the synthesis of EU from CO_(2) and EDA decreased.Further characterization showed the Mn_(2)O_(3) catalyst possessed a greater Mn^(3+)/Mn4+ratio and more surface oxygen vacancies than the MnO_(2) and Mn_(3)O_(4),which improved its capacity to adsorb and activate CO_(2) and EDA.After four recycling runs,the EDA conversion slightly declined from 82%to 56%on Mn_(2)O_(3) catalyst,while no obvious change in EU selectivity was observed.The loss of surface Ov contents and Mn^(3+)proportion were concluded as main reasons for the decrease in catalytic activity over Mn_(2)O_(3) catalyst.This work demonstrated a metal oxide catalyst that was efficient in producing EU from CO_(2) and EDA.
基金financially supported by the National Key Research and Development Program of China(Grant Nos.2023YFB2604005)the National Key Research and Development 451 Program of China(Grant No.2021YFC3100803)the Yangtze River Water Science Research Joint Fund Key Project of National Natural Science Foundation of China(Grant No.U2340231).
文摘Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane material is convenient for engineering applications;however,the compressive behaviour and feasibility of sprayed polyurethane material as a compressible layer remain unclear.To address this gap,this study conducts uniaxial compression tests and scanning electron microscope(SEM)tests to investigate the compressive behaviour of the rigid foams fabricated from a self-developed polyurethane spray material.A peridynamics model for the composite lining with a polyurethane compressible layer is then established.After validating the proposed method by comparison with two tests,a parametric study is carried out to investigate the damage evolution of the composite lining with a polyurethane compressible layer under various combinations of large deformations and compressible layer parameters.The results indicate that the polyurethane compressible layer effectively reduces the radial deformation and damage index of the secondary lining while increasing the damage susceptibility of the primary lining.The thickness of the polyurethane compressible layer significantly influences the prevention effect of large deformation-induced damage to the secondary lining within the density range of 50e100 kg/m^(3).In accordance with the experimental and simulation results,a simple,yet reasonable and convenient approach for determining the key parameters of the polyurethane compressible layer is proposed,along with a classification scheme for the parameters of the polyurethane compressible layer.
基金the financial support from the Fujian Science Foundation for Outstanding Youth(2023J06039)the National Natural Science Foundation of China(Grant No.41977259,U2005205,41972268)the Independent Research Project of Technology Innovation Center for Monitoring and Restoration Engineering of Ecological Fragile Zone in Southeast China(KY-090000-04-2022-019)。
文摘Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.
基金supported by Fundamental Research Program of Shanxi Province(202203021221303)。
文摘Transformation of urea and glycerol to glycerol carbonate is an environmental friendly and economical process.Catalysts play an indispensable role in the process.Although many catalysts have been developed,the performance of the catalysts still cannot meet the needs of industrialization.In this paper,research progress of the homogeneous and heterogeneous catalysts of the reaction over the past 20 years were reviewed systematically.According to the types and active centers of catalysts,the catalysts were classified systematically and analyzed in detail.The typical reaction mechanisms were also summarized.The research and development direction of catalysts is made more explicit through systematic classification and mechanism analysis.The article reveals more novel catalysts have been designed and used for the reaction,such as mixed metal oxides with special structures,solid wastes and non-metallic materials.This work summarized the current state of research and prospected possible routes for design of novel catalysts.It is hoped that this review can provide some references for developing efficient catalysts.
基金supported by the Applied Basic Research Program of Yunnan Province(202101BE070001-032)Yunnan Major Scientific and Technological Projects(No.202202AG050001).
文摘The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea oxidation reaction(UOR).Herein,we report the loosely porous CoOOH nano-architecture(CoOOH LPNAs)with hydrophilic surface and abundant oxygen vacancies(Ov)on carbon fiber paper(CFP)by electrochemical reconstruction of the CoP nanoneedles precursor.The resulting three-dimensional electrode exhibited an impressively low potential of 1.38 V at 1000 mA·cm^(−2) and excellent durability for UOR.Furthermore,when tested in an anion exchange membrane(AEM)electrolyzer,it required only 1.53 V at 1000 mA·cm^(−2) for industrial urea-assisted water splitting and operated stably for 100 h without degrada-tion.Experimental and theoretical investigations revealed that rich oxygen vacancies effectively modulate the electronic structure of the CoOOH while creating unique Co3-triangle sites with Co atoms close together.As a result,the adsorption and desorption processes of reactants and intermediates in UOR could be finely tuned,thereby significantly reducing ther-modynamic barriers.Additionally,the superhydrophilic self-supported nanoarray structure facilitated rapid gas bubble release,improving the overall efficiency of the reaction and preventing potential catalyst detachment caused by bubble accumulation,thereby improving both catalytic activity and stability at high current densities.
文摘Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.
基金supported by the National Natural Science Foundation of China(Nos.42207353 and 42277408)the Key Research and Development Program of Jiangsu Province of China(BE2021378)+1 种基金Jiangsu Agricultural Science and Technology Independent Innovation Fund of China(CX(21)-1009)the Earmarked Fund of China Agriculture Research System(CARS-10-Sweetpotato)。
文摘Dear Editor,Environmental pollution from microplastics(MPs)has recently gained attention as a potential environmental hazard(Chia et al.,2021).Agricultural soils could contain more MPs than the ocean by 2050 because more MPs enter the soil than the ocean(Nizzetto et al.,2016).The carbon(C)-C backbone of degradation-resistant MPs provides considerable stability in the soil,where they can remain for several decades(Iqbal et al.,2023).
文摘In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utilization of ethoxylated castor oil increases tensile strength of PU up to 2.75 times(from3.2 to 8.8MPa),compared to PU based on neat castor oil.The PU composites filed with birch flour,diatomite and their mixture were prepared using home-made dissolver with cutter-shaped attachment at the speed of 1500 min−1.The tensile strength of PU composites filled with birch flour increases up to two time at loading 5–30 wt.%.Application of combined birch flour/diatomite additives has similar effect.The tensile strength of PU composites based on one to one mixture of ethoxylated and neat castor oil and filled with birch flour or combined birch flour/diatomite additives increases sharply up to 16–17 fold(up to 18.1 MPa).The birch flour and diatomite wellsoaked polymer matrix.The main factor determining mechanical performance is the morphology of PU samples and composites.Formation of ordered lamella-like structure of amorphous phase of PU matrix leads to an increase in mechanical performance and glass transition temperatures.Formation of disordered unstructured soft phase of starting PU leads to a decline of these functional properties.
基金support by the Department of Science&Technology of Zhejiang Province under grant No.2024C01095the Fundamental Research Funds for the Provincial Universities of Zhejiang under grant No.RF-C2022008the National Natural Science Foundation of China(NSFC)under grant Nos.U20A20253,52372235,and 22279116。
文摘Aqueous sodium-ion batteries(ASIBs)have garnered significant attention as promising candidates for large-scale energy storage applications.This interest is primarily due to their abundant resource availability,environmental friendliness,cost-effectiveness,and high safety.However,their electrochemical performance is limited by the thermodynamic properties of water molecules,resulting in inadequate cycling stability and insufficient specific energy density.To address these challenges,this study developed a hydrogen-bond enhanced urea-glycerol eutectic electrolyte(UGE)to expand the electrochemical stability window(ESW)of the electrolyte and suppress corresponding side reactions.The eutectic component disrupts the original hydrogen bonding network in water,creating a new,enhanced network that reduces the activity of free water and forms a uniform,dense passivation layer on the anode.As a result,the optimized composition of UGE exhibits a broad ESW of up to 3 V(-1.44 to 1.6 V vs.Ag/AgCl).The Prussian blue(PB)/UGE/NaTi_(2)(PO_(4))_(3)@C full cell exhibits an exceptionally long lifespan of 10,000 cycles at 10 C.This study introduces a low-cost,ultra-long-life ASIB system,utilizing a green and economical eutectic electrolyte,which expands the use of eutectic electrolytes in aqueous batteries and opens a new research horizon for constructing efficient electrochemical energy storage and conversion.
基金financially supported by Applied Basic Research Project of Qinghai province(2023-ZJ-774)。
文摘Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agents,functional dendritic polyurethanes with nano structure were successfully prepared by one-pot method.The single molecule size and surface morphology were characterized by dynamic light scattering,transmission electron microscopy and scanning electron microscopy,and the molecular size in the dry state was 11 to 18 nm.The prepared materials were used as the boron adsorbents,and the effects of pH,time,boron solution concentration and temperature on the adsorption were studied.The results showed that the capacity of adsorbed boron could reach 110-130 mg·g^(-1).Adsorption was a homogeneous monolayer adsorption controlled by chemisorption,and adsorption thermodynamics showed that was a spontaneous endothermic process.Adsorption behavior was best described by the pseudo-second-order kinetic model and the Langmuir isotherm.This study also showed that it was difficult for ortho/meta-hydroxyl groups to chelate with H_(3)BO_(3) and other polyborates,and the chelates mainly had good chelating properties with B(OH)_(4)^(-),and the chelates formed had large steric hindrance.At the same time,increasing the number of hydroxyl groups of functional monomers was beneficial to increase the adsorption capacity of materials.In addition,the cyclic adsorption/desorption experiments showed that DPUs have good cyclic stability.At the same time,the adsorption results of the original salt lake brine showed that other metal ions in the brine had little effect on the adsorption of boron,and the adsorption capacity was as high as52.93 mg·g^(-1),and the maximum adsorption capacity was obtained by Adams-Bohart model to58.80 mg·g^(-1).The outstanding selectivity and adsorption capacity of these materials have broad potential application,and are expected to be used for the efficient adsorption and removal in boroncontaining water bodies.
基金supported by grants from the initial funding of National Natural Science Foundation of China(No.8227020480)。
文摘Background Previous studies have shown a relationship between elevated blood urea nitrogen(BUN)level and poor outcomes in several diseases,but data on the prognostic significance of postoperative BUN in elderly patients undergoing valve replacement surgery(VRS)remained sparse.Methods BUN was measured immediately after VRS.A total of 3118 elderly patients were enrolled and divided into four groups according to the quartiles of postoperative BUN:Q1,<5.6 mmol/L;Q2,5.6-6.8 mmol/L;Q3,6.8-8.4 mmol/L and Q4,≥8.4 mmol/L.The associations of postoperative BUN with in-hospital and 1-year mortality were evaluated.Results The incidence of inhospital death(1.0%vs.3.3%vs.3.3%vs.8.4%,P<0.001)and major adverse clinical events(5.1%vs.7.8%vs.9.9%vs.19.1%,P<0.001)was significantly higher in patients with a high BUN level.BUN was independently associated with all-cause in-hospital mortality[odds ratio(OR):1.11,95%confidential interval(CI):1.07-1.16,P<0.001].The receiver operating characteristic(ROC)curve showed that BUN>9 mmol/L had a sensitivity of 48.4%and specificity of 81.8% for predicting in-hospital death[area under curve(AUC):0.705,95%CI:0.658-0.753,P<0.001].Kaplan-Meier survival curves showed that patients with BUN>9 mmol/L had a higher one-year mortality than those without(log-rank test:91.7,P<0.001).Multivariate analysis showed that BUN>9 mmol/L was an independent predictor for one-year mortality[hazard ratio(HR):1.67,95%CI:1.23-2.28,P=0.001].Conclusions This study provided strong evidence that increased postoperative BUN level was associated with poor prognosis in elderly patients undergoing VRS.
基金financially supported by the National Natural Science Foundation of China(Nos.21971177 and 52503155)Natural Science Foundation of the Jiangsu Higher Education Institution of China(No.22KJA150004)+7 种基金China Scholarship Council(No.202206920034)Research Foundation Flanders(FWO)(Application 1S34725N)Priority Academic Program Development(PAPD)of Jiangsu Higher Education InstitutionsJiangsu Key Laboratory of Advanced Functional Polymers Design and ApplicationSoochow UniversitySuzhou Key Laboratory of Macromolecular Design and Precision SynthesisProgram of Innovative Research Team of Soochow Universityfunding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Program 101021081(ERC-AdG-2020,CiMaC-project)。
文摘In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials with excellent room-temperature hardness were obtained.Fine-tuning the selenonium content established a synergy between antibacterial performance and network dynamics,as evidenced by vitrimer-like rheological behavior at elevated temperatures.Consequently,the coatings exhibited outstanding reprocessability while maintaining high transparency and structural stability after prolonged saltwater exposure.These integrated features underscore the potential of the developed cationic PU coatings as robust,multifunctional materials for electronic device protection and marine antifouling,combining long-term transparency,recyclability,and antibacterial durability.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00451587)supported by Post-plastic Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金supported by Shiraz University of Medical Sciences,Shiraz,Iran(grant No.:17780).
文摘Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,collagen and gold nanoparticles with random and aligned nanofiber morphologies.The nanoparticles were green-synthesized using saffron extract.Nanoparticle characterizations with UV-Vis.spectroscopy and DLS illustrated theoretical and hydrodynamic diameters of around 7 and 13 nm,respectively,having zeta potential of−37 mV.SEM and TEM micrographs showed the morphology and diameters of obtained nanofibers.Also,further characterization were done by ATR-FTIR,XRD and TGA investigations and degradation studies.Contact angle measurements showed hydrophilic nature of the scaffolds(59±0.6°for aligned PU/Col/Au50 nanofibers compared to 120±2.6°for random PU nanofibers).Mechanical testing demonstrated appropriate tensile properties of the scaffolds for cardiac tissue engineering(Young’s modulus:1.53±0.07 MPa for aligned PU/Col/Au50 nanofibers compared to 0.4±0.05 MPa for random PU nanofibers).Finally,alamar blue assay revealed proper survival of the cells of HUVEC cell line on the prepared scaffolds,where the highest percentages were observed for random and aligned PU/Col/Au50 nanofibers.According to the findings,the fabricated PU/Col/AuNPs nanofibrous scaffolds could be considered as potential cardiac patches.
基金supported by the National Natural Science Foundation of China(No.42107052)Beijing Natural Science Foundation(No.JQ21031).
文摘As a widely used fertilizer,urea significantly promotes the leaching of dissolved organic nitrogen(DON)in soils and aggravates nitrogen contamination in groundwater.Clayminerals are considered the most important factor in retaining DON.However,the effect of urea on the retention of DON with different molecular weights by clay minerals is unknown.In this study,the retention of both low-molecular weight DON(LMWD)and high-molecular weight DON(HMWD)by clay minerals in the presence of urea was investigated.For this purpose,batch adsorption and soil column leaching experiments,characterization analysis(Fourier transform infrared spectroscopy X-ray diffraction,and X-ray photoelectron spectroscopy),and molecular dynamics simulations were carried out.Urea had a positive effect on the adsorption of LMWD,whereas a competitive effect existed for the adsorption of HMWD.The dominant interactions among DON,urea,and clay minerals included H-bonding,ligand exchange,and cation exchange.The urea was preferentially adsorbed on clay minerals and formed a complex,which provided more adsorption sites to LMWD and only a few to HMWD.The presence of urea increased the retention of LMWD and decreased the retention of HMWD in clay minerals.The retention capacity of LMWD increased by 6.9%–12.8%,while that of HMWD decreased by 6.7%–53.1%.These findings suggest that LMWD tended to be trapped in soils,while HMWD was prone to be leached into groundwater,which can be used to evaluate the leaching of DON from soil to groundwater.
