Converting waste plastics directly into valuable aromatic chemicals is a promising,cost-effective recycling strategy.Traditional zeolite-catalyzed cracking of polyolefins to produce aromatics often needs high temperat...Converting waste plastics directly into valuable aromatic chemicals is a promising,cost-effective recycling strategy.Traditional zeolite-catalyzed cracking of polyolefins to produce aromatics often needs high temperatures and faces issues like low selectivity for liquid aromatics,separation difficulties,and rapid catalyst deactivation due to coking.To address this,a multifunctional Ni/HZSM-5 catalyst was developed to efficiently upgrade various polyolefins—including polyvinyl chloride—into gaseous alkanes(C_(1)–C_(5))and easily separable liquid aromatics(C_(6)–C_(12))at 400°C,without added solvents or hydrogen.Aromatic products make up 57.1 wt%of total output,with more than 97.8%selectivity for the liquid phase and a BTX(benzene,toluene,and xylene)selectivity of 76.1%.The high activity and selectivity for aromatics stem from synergistic interactions between Ni nanoparticles(NPs)and acid sites in the zeolite,which promote selective C–C bond breaking and control hydrogenolysis and aromatization pathways.This synergy allows precise control over the distribution of products by carbon number and favors the formation of separable aromatics.Notably,the catalyst also prevents coking by hydrogenolyzing and hydrogenating reactive intermediates before they form stable graphite-like deposits.Consequently,Ni/ZSM-5 catalyst demonstrates excellent stability,maintaining consistent aromatics yield over 13 consecutive cycles and processing over 30 times its weight in plastics without regeneration.After regeneration,the activity of the catalyst was fully restored,highlighting its potential for industrial use.This work offers valuable insights for designing durable,high-activity catalysts,providing a practical route to improve plastic recycling technologies.展开更多
Both genders of the dioecious gymnosperm Ginkgo bilob a have distinct practical production and application uses,so quick,accurate identification of males and females is important for early seedling breeding.To develop...Both genders of the dioecious gymnosperm Ginkgo bilob a have distinct practical production and application uses,so quick,accurate identification of males and females is important for early seedling breeding.To develop a fast method to identify the sexes,we used the Easy DNA extraction(EZ-D)method to extract DNA from leaves within1 min for use with the recombinase polymerase amplification-lateral flow dipstick(RPA-LFD)system and identify the sex.A portable nucleic acid detection card kit(PNADCK)was used for on-site analysis.This method facilitates rapid extraction of nucleic acids from a single and can accurately detect 100 pg/μL of G.biloba female genomic DNA within20 min at 39°C.The EZ-DRPA-LFD-PNADCK system enables precise on-site determination of G.bilob a leaf sex and is rapid,efficient,sensitive,and convenient,greatly enhancing productivity for G.biloba because seedlings with specific sex characteristics can be selected at an earlier stage,planting strategies can be optimized,and production efficiency improved.展开更多
The restriction of KB averaging method is discussed and asymptotic solution of the weakly nonlinear and forced oscillation u″+ω20u=εkcos ωt-εu3 is obtained by Struble technique. The conclusion about this oscillat...The restriction of KB averaging method is discussed and asymptotic solution of the weakly nonlinear and forced oscillation u″+ω20u=εkcos ωt-εu3 is obtained by Struble technique. The conclusion about this oscillation derived with other method is discussed. The results show that KB method will break down when a and θ in the zeroth solution of above eqation are not slowly varying functions of time t. The stationary solution of weakly nonlinear oscillation, u″+ω20u=εkcosω(ε)t-εu3 is also analysed.展开更多
In this study,the solid structure,dissolution behavior,thermodynamic properties and nucleation kinetics of malonamide were explored.Firstly,the Hirshfeld surface analysis and molecular electrostatic potential surface ...In this study,the solid structure,dissolution behavior,thermodynamic properties and nucleation kinetics of malonamide were explored.Firstly,the Hirshfeld surface analysis and molecular electrostatic potential surface were plotted to reveal the percentage contribution of various intermolecular contacts and location of the strongest hydrogen bond.Next,the solubility of malonamide in 12 solvents was determined by dynamic method at temperatures from 278.15 K to 318.15 K.Four thermodynamic models were applied to analyze solubility results.In addition,the thermodynamic properties were calculated to further analyze and discuss the dissolution behavior of malonamide.Moreover,the physicochemical properties of solvents were explored to express the solvent effects.The results illustrate“like dissolves like”,“mass transfer”and“solvent–solute interaction”rules play the synergistic effects on the dissolution process.The molecular dynamic simulation,including radial distribution function analysis and solvent free energy,was used to further explain the dissolution behavior.At last,the nucleation rate and effective interfacial energy in methanol solvent was measured and calculated to reveal the nucleation behaviour.展开更多
To study the volatile organic compounds(VOCs)emission characteristics of industrial enterprises in China,6 typical chemical industries in Yuncheng City were selected as research objects,including the modern coal chemi...To study the volatile organic compounds(VOCs)emission characteristics of industrial enterprises in China,6 typical chemical industries in Yuncheng City were selected as research objects,including the modern coal chemical industry(MCC),pharmaceutical industry(PM),pesticide industry(PE),coking industry(CO)and organic chemical industry(OC).The chemical composition of 91 VOCs was quantitatively analyzed.The results showed that the emission concentration of VOCs in the chemical industry ranged from 1.16 to 155.59 mg/m^(3).Alkanes were the main emission components of MCC(62.0%),PE(55.1%),and OC(58.5%).Alkenes(46.5%)were important components of PM,followed by alkanes(23.8%)and oxygenated volatile organic compounds(OVOCs)(21.2%).Halocarbons(8.6%-71.1%),OVOCs(9.7%-37.6%)and alkanes(11.2%-27.0%)were characteristic components of CO.The largest contributor to OFP was alkenes(0.6%-81.7%),followed by alkanes(9.3%-45.9%),and the lowest onewas alkyne(0%-0.5%).Aromatics(66.9%-85.4%)were the largest contributing components to SOA generation,followed by alkanes(2.6%-28.5%),and the lowest one was alkenes(0%-4.1%).Ethylene and BTEX were the key active species in various chemical industries.The human health risk assessment showed workers long-term exposed to the air in the chemical industrial zone had a high cancer and non-cancer risk during work,and BTEX and dichloromethane were the largest contributors.展开更多
In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves th...In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves the electrical conductivity of the whole electrode,but also protects the inner Si nanoparticles(Si NPs)from rupturing and being damaged by undesired side reactions with the electrolyte.As a result,the Si@rGO/ZrO_(2) anode delivers high initial discharge capacity of 3046 mAh·g^(−1) at 1.0 A·g^(−1).After 100 cycles,it can be maintained at 613 mAh·g^(−1),which is much higher than that of either the pure Si NPs(31 mAh·g^(−1))or the Si@rGO(261 mAh·g^(−1)).Even at 2 A·g^(−1),it still provides superior specific capacity of 834 mAh·g^(−1),while the pure Si anode merely possesses the capacity of 41 mAh·g^(−1).Moreover,the density functional theory calculations point out that ZrO_(2) layer can effectively enhance the adsorption energy of Li+and optimize the migration paths of Li+,ensuring the electrochemical performance of Si@rGO/ZrO_(2) composite anode.Furthermore,the Li+storage mechanism and low volume expansion of Si@rGO/ZrO_(2) anode is investigated by ex-situ X-ray photoelectron spectroscopy and morphological evolution upon cycling,respectively.展开更多
To efficiently diminish the Pt consumption while concurrently enhancing the anodic reaction kinetics,a straightforward synthesis for PtPdAg nanotrees(NTs)with exceedingly low Pt content is presented,utilizing the galv...To efficiently diminish the Pt consumption while concurrently enhancing the anodic reaction kinetics,a straightforward synthesis for PtPdAg nanotrees(NTs)with exceedingly low Pt content is presented,utilizing the galvanic replacement reaction between the initially prepared PdAg NTs and Pt ions.Due to the multilevel porous tree-like structure and the incorporation of low amounts of Pt,the electrocatalytic activity and stability of PtPdAg NTs are markedly enhanced,achieving 1.65 and 1.69 A·mg^(-1)Pt+Pd for the anodic reactions of formic acid oxidation(FAOR)and methanol oxidation(MOR)within DLFCs,surpassing the performance of PdAg NTs,as well as that of commercial Pt and Pd black.Density functional theory(DFT)calculations reveal that the addition of low amounts of Pt leads to an increase in the d-band center of PtPdAg NTs and lower the COads adsorption energy to-1.23 eV,enhancing the anti-CO toxicity properties optimally.This approach offers an effective means for designing low Pt catalysts as exceptional anodic electrocatalysts for direct liquid fuel cells.展开更多
The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid...The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid(FDCA)from 5-hydroxymethylfurfural(HMF)oxidation is one of the most promising means for the production of bioplastic monomers.In this work,we constructed a novel P-doped Ni_(3)S_(2)and Ni heterojunction on nickel foam(P-Ni_(3)S_(2)/Ni/NF)using electrodeposition methods and thermal sulfuration techniques as a bifunctional catalyst for the simultaneous anodic oxidation of HMF to FDCA(HMFOR)and the cathodic hydrogen evolution reaction(HER).On one hand,the synergistic promotion of P doping and the heterojunction of Ni_(3)S_(2)and Ni accelerated electron transfer,and on the other hand,the structure of three-dimensional microsphere stacking on NF surface to form macropores enhances the exposure of catalytically active sites.The prepared P-Ni_(3)S_(2)/Ni/NF exhibited remarkable performance with high HMF conversion(99.2%),FDCA yield(98.1%),and Faraday efficiency(98.8%),and excellent stability with good product selectivity for 7 consecutive cycles,which stands at a higher level than majority of previously published electrocatalysts.Furthermore,P-Ni_(3)S_(2)/Ni/NF also shows a significant response in HER.By using HMFOR and HER as the anodic reaction and cathodic reaction,respectively,the biomass upgrading and hydrogen production can be carried out simultaneously.The synthesized P-Ni_(3)S_(2)/Ni/NF only need a voltage of 1.31V to achieve a current density of 10mA/cm^(2)in a two-electrode system of HMFOR and HER,which is much lower than that of 1.48 V in OER and HER process,thus potentially reducing the cost of this process.展开更多
Mn nanoparticles(nano-Mn)were successfully synthesized and doped into MgH_(2) to improve its de/hydrogenation properties.Compared with MgH_(2),the onset desorption temperature of 10 wt.%nano-Mn modified MgH_(2) was de...Mn nanoparticles(nano-Mn)were successfully synthesized and doped into MgH_(2) to improve its de/hydrogenation properties.Compared with MgH_(2),the onset desorption temperature of 10 wt.%nano-Mn modified MgH_(2) was decreased to 175℃ and 6.7,6.5 and 6.1 wt.%hydrogen could be released within 5,10 and 25 min at 300,275 and 250℃,respectively.Besides,the composite started to take up hydrogen at room temperature and absorbed 2.0 wt.%hydrogen within 30 min at low temperature of 50℃.The hydrogenation activation energy of MgH_(2) was reduced from(72.5±2.7)to(18.8±0.2)kJ/mol after doping with 10 wt.%nano-Mn.In addition,the MgH_(2)+10 wt.%nano-Mn composite exhibited superior cyclic property,maintaining 92%initial capacity after 20 cycles.展开更多
Arabidopsis thaliana seedlings were cultivated in 0-500 μmol/L of extraneous cerium （Ce） for 7 d to investigate the toxicity, uptake and translocation of rare earth elements （REEs）. The results showed that Ce cou...Arabidopsis thaliana seedlings were cultivated in 0-500 μmol/L of extraneous cerium （Ce） for 7 d to investigate the toxicity, uptake and translocation of rare earth elements （REEs）. The results showed that Ce could be largely absorbed by the roots ofA. thaliana and translocated to the shoots. But the uptake rates of Ce by the roots were much higher than the translocation rates from roots to shoots. Ultrastructural analysis revealed that Ce was mainly distributed on the cell wall. At higher concentration, Ce could also enter cell, destroy the ultrastructure of cells and disturb the intrinsic balance of nutrient elements of A, thaliana, Addition of Ce （50-500 μmol/L） to the culture medium significantly inhibited the elongation of primary roots, decreased chlorophyll content, rosette diameter and fresh mass of plants. The damage increased with the increase of Ce concentration in culture medium, although primary root elongation, chlorophyll content, and rosette diameter were stimulated by relatively low concentration （0.5 μmol/L） of Ce. Thus, it is speculated that REEs may become a new type contamination if we don＇t well control the release of REEs into the environment.展开更多
Particulate matter(i.e.,PM_(1.0) and PM_(2.5)),considered as the key atmospheric pollutants,exerts negative effects on visibility,global climate,and human health by associated chemical compositions.However,our underst...Particulate matter(i.e.,PM_(1.0) and PM_(2.5)),considered as the key atmospheric pollutants,exerts negative effects on visibility,global climate,and human health by associated chemical compositions.However,our understanding of PM and its chemical compositions in Beijing under the current atmospheric environment is still not complete after witnessing marked alleviation during 2013–2017.Continuous measurements can be crucial for further air quality improvement by better characterizing PM pollution and chemical compositions in Beijing.Here,we conducted simultaneous measurements on PM in Beijing during 2018–2019.Results indicate that annualmean PM_(1.0) and PM_(2.5) concentrations were 35.49±18.61μg/m^(3) and 66.58±60.17μg/m^(3),showing a positive response to emission controls.The contribution of sulfate,nitrate,and ammonium(SNA)played an enhanced role with elevated PM loading and acted as the main contributors to pollution episodes.Discrepancies observed among chemical species between PM_(1.0) and PM_(2.5) in spring suggest that sand particles trend to accumulate in the range of 1–2.5μm.Pollution episodes occurred accompanied with southerly clusters and high formation of SNA by heterogeneous reactions in summer and winter,respectively.Results from positive matrix factorization(PMF)combined with potential source contribution function(PSCF)models showed that potential areas were seasonal dependent,secondary and vehicular sources became much more important compared with previous studies in Beijing.Our study presented a continuous investigation on PM and sources origins in Beijing,which provides a better understanding for further emission control as well as a reference for other cities in developing countries.展开更多
Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer...Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer on the surface of the HMX was observed by scanning electron microscopy(SEM),and a series of in-depth characterization confirmed the successful generation of CS and the coreshell structure of the samples.Differential scanning calorimeter(DSC)proves that the crystal transition temperature(204℃)and high temperature decomposition exothermal temperature(284℃)of HMX@CS is almost unchanged compared with pure HMX,which means HMX and CS have good compatibility.Then,the H50 of the samples also increased continuously(16.6 cm→33.7 cm)when the CS shell content increased from 1%to 5%,indicating that the CS shell has a certain buffering performance,and CS will absorb some heat and melt under the stimulation of impact due to its low melting point,which improved impact sensitivity of HMX effectively further.Moreover,HMX@CS has excellent hydrophobic and oleophilic performance,shows excellent wettability with lipid binder,and samples with appropriate CS shell content can continue to combustion stably after covering water.This waterproof and low sensitivity coating provides a new way for the development of multifunctional energetic materials.展开更多
A self-made directional solidification device was used to fabricate d 80 mm high purity aluminum ingots. SEM and AFM were used to detect the shape of grain boundaries. The orientation of the grain was studied by X-ray...A self-made directional solidification device was used to fabricate d 80 mm high purity aluminum ingots. SEM and AFM were used to detect the shape of grain boundaries. The orientation of the grain was studied by X-ray diffractometry. The results show that the nucleation points locate at the intersections of three adjacent grains. The lattice orientation of grains does not alter in the horizontal direction, but gradually approaches the optimum growth direction in the vertical direction during the growth process. All the grains suffer the competition and only the one whose orientation is closest to the preferred direction can occupy the final growth space.展开更多
High strength Al-Zn-Mg-Cu alloys were prepared by spray deposition and casting techniques. The microstructures of the Al-Zn-Mg-Cu alloys were studied using scanning electron microscopy, transmission electron microscop...High strength Al-Zn-Mg-Cu alloys were prepared by spray deposition and casting techniques. The microstructures of the Al-Zn-Mg-Cu alloys were studied using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Secondary phases in the microstructures of the alloys prepared by spray deposition and conventional cast were examined. The results indicate that under the conventional casting condition, the microstructure of the alloy revealed the presence of coarse Al/Mg（ZnCu）2 eutectic phases, and the spray deposited process causes an obvious modification in size, morphology, and distribution of secondary phases in the microstructure as well as reduction of segregation. The superior microstructure of the spray-deposited Al-Zn-Mg-Cu alloy was attributed to the high cooling rate, and associated with the rapid solidification process.展开更多
As a promising hydrogen storage material,the practical application of magnesium is obstructed by the stable thermodynamics and sluggish kinetics.In this paper,three kinds of NiTiO3catalysts with different mole ratio o...As a promising hydrogen storage material,the practical application of magnesium is obstructed by the stable thermodynamics and sluggish kinetics.In this paper,three kinds of NiTiO3catalysts with different mole ratio of Ni to Ti were successfully synthesized and doped into nanocrystalline Mg to improve its hydrogen storage properties.Experimental results indicated that all the Mg-NiTiO3composites showed prominent hydrogen storage performance.Especially,the Mg-NiTiO3/TiO2composite could take up hydrogen at room temperature and the apparent activation energy for hydrogen absorption was dramatically decreased from 69.8±1.2(nanocrystalline Mg)k J/mol to 34.2±0.2 k J/mol.In addition,the hydrogenated sample began to release hydrogen at about 193.2℃and eventually desorbed 6.6 wt%H2.The desorption enthalpy of the hydrogenated Mg-NiTiO3-C was estimated to be 78.6±0.8 k J/mol,5.3 k J/mol lower compared to 83.9±0.7 k J/mol of nanocrystalline Mg.Besides,the sample revealed splendid cyclic stability during 20 cycles.No obvious recession occurred in the absorption and desorption kinetics and only 0.3 wt%hydrogen capacity degradation was observed.Further structural analysis demonstrates that nanosizing and catalyst doping led to a synergistic effect on the enhanced hydrogen storage performance of Mg-NiTiO3-C composite,which might serve as a reference for future design of highly effective hydrogen storage materials.展开更多
OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(...OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite nanofibers is about 200 nm,the grains size is about 1-3 nm,and the fiber surface is rough.The electrochemical test results show that the heterojunction of the prepared Ni_(3)Fe/Ni_(4)S_(3)/Ni/C hybrid crystal composite nanofiber has synergistic effect with sulfide,and exhibits good electrocatalytic activity of water decomposition and OER in alkaline system.The OER electrocatalytic performance of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite electrode prepared via a heat treatment at 1000℃process was tested in 1 mol/L KOH electrolytes.The results show that the overpotential is about 298 mV,the Tafel slope is about 74 mV?dec-1,and the surface resistance is about 1.69Ω·cm^(2),at the current density of 10 mA·cm^(-2).展开更多
In this study,low-field nuclear magnetic resonance(LF-NMR)was used to collect the transverse relaxation signals of camphor seeds that had been dried at different temperatures and for different durations.The transverse...In this study,low-field nuclear magnetic resonance(LF-NMR)was used to collect the transverse relaxation signals of camphor seeds that had been dried at different temperatures and for different durations.The transverse relaxation time of the hydrogen nucleus was obtained by SIRT(Simultaneous Iterative Reconstruction Technique)inversion,and the correlation between the moisture content on dry basis and the amplitude of NMR signal of camphor seeds sampled at different drying stages was analyzed.The results showed that water existed in three main forms strongly bound water,weakly bound water and free water in camphor seeds.During the drying process,the peak position of strongly bound water remained unchanged,but the peak positions of weakly bound water and free water fluctuated.Drying rate increased with drying temperature increasing.In addition,there was a very significant linear relationship between the total NMR signal amplitude and moisture content on dry basis,and the correlation coefficient reached 0.984 4.展开更多
Iron-chromium-aluminum(FeCrAl)alloys with different content of niobium(Nb)—0,0.4 wt%,0.8 wt%,and 1.2 wt%—were designed and prepared.All samples were then irradiated with 2.4 MeV Fe^(2+)ion to the dose of 1 and 15 di...Iron-chromium-aluminum(FeCrAl)alloys with different content of niobium(Nb)—0,0.4 wt%,0.8 wt%,and 1.2 wt%—were designed and prepared.All samples were then irradiated with 2.4 MeV Fe^(2+)ion to the dose of 1 and 15 displacements per atom(dpa)at 400℃.The formations of dislocation loops induced by self-ion irradiation in these alloys were investigated by transmission electron microscopy(TEM).Nano-indentation tests were used to assess the hardness and irradiation hardening of samples.For the samples before irradiation,the(Fe,Cr)_(2)(Nb,Mo)Laves phases density and the nano-indentation hardness increased with increasing Nb content of the samples.After irradiation to 1 and 15 dpa,both of a/2<111>and a<100>dislocation loops were produced but no voids orα’phase were found in all samples.With increasing Nb content of the samples,the size of dislocation loops increased first and then decreased,while the total volume number density decreased and then increased.The fraction of a<100>dislocation loops increased first and then decreased with increasing Nb content,and increased with increasing irradiation dose.Dislocation networks and the amorphization of the Laves phases were observed in the samples with irradiation dose of 15 dpa.Irradiation hardening of Nb free samples was two to four times that of Nb containing samples,and the irradiation hardening increased with increasing Nb content of Nb containing samples.The experimental results indicate that the increase of Nb content in Fe Cr Al alloys can increase the density of Laves phases,leading to the decrease of Mo content and increase of Cr content in the matrix.The competition between the two types of solutes affects the nucleation and growth of the dislocation loops.展开更多
Colloidal particles,heterogeneous mixture with various organic components and continuous molecular weight(MW)distribution,is omnipresent in lake sediments and substantially influence the retention,transportation,and f...Colloidal particles,heterogeneous mixture with various organic components and continuous molecular weight(MW)distribution,is omnipresent in lake sediments and substantially influence the retention,transportation,and fate of contaminants in lake ecosystem.We sampled and extracted sedimentary colloids from different ecology regions in Taihu Lake,Jiangsu,East China,in June 2020,and they were further separated into four different particle size ranges by tangent ultrafiltration,and the properties of colloids were studied in various methods,including zeta potential analysis,transmission electron micrograph images(TEM),Fourier transformation infrared(FTIR),and 3D fluorescence.Results show that the surface of the colloids is covered with organic macromolecular substances,such as humuslike substances and protein-like substances.There were significant differences in molecular weight and fraction content of colloids in the sediments from macrophyte-dominant(MD)area and algae-dominant(AD)area in the lake.Colloids from MD area are mainly composed of humic acid,protein,and fulvic acid;the content of fulvic acid is lower than that of humic acid and protein.The humic acid exists mainly in small molecular weight(10-100 kDa),protein exists in mainly large molecular weight colloids(0.45-1μm).Colloids from AD area are mainly composed of humic acid,and mainly distributed in the molecular weight(10 kDa-0.45μm).The presence of humic acid inhibits effectively the agglomeration of the colloids.Especially,the stability of colloids is closely related to the molecular weight,with low molecular weight from MD area show higher stability.The existence of humic acid in colloids increases the electrostatic repulsion between colloidal particles,which can effectively inhibit the agglomeration of colloids,thus enhancing the stability of colloids.Furthermore,both monovalent and divalent electrolytes enhance colloidal aggregation,and the low-molecular-weight(LMW)colloid fraction exhibits higher stability efficiency than the high-molecular-weight(HMW)colloidal.展开更多
In order to better understand why the corrosion behavior of carbon steel exposed in Nansha atmospheric environment is very serious, the effect of sodium, potassium and magnesium chlorides deposited on carbon steel sur...In order to better understand why the corrosion behavior of carbon steel exposed in Nansha atmospheric environment is very serious, the effect of sodium, potassium and magnesium chlorides deposited on carbon steel surface has been studied under atmosphere conditions by wet/dry accelerated test. The difference of corrosion behavior and surface structure in Na+, K+, and Mg2+ containing atmosphere has been investigated by thickness loss, scanning electron microscope, X-ray diffraction and electrochemical techniques. The results indicate that the thickness loss of carbon steel exposed in different metal cations containing atmospheric environment increases in the order of Na+, K+, Mg2+. The hard metal cation can promote the dissolution of the steel to a certain extent. In Mg2+ containing atmosphere, the relative content of β-FeOOH is rather higher and the protective ability index α */γ * decreases in the order of Na+, K+, Mg2+. The corrosion current density of both bare carbon steel and the rusted carbon steel increases in the order of Na+, K+, Mg2+. The polarization resistance and the charge transfer resistance decreases in the order of Na+, K+, Mg2+.展开更多
基金supported by the National Key R&D Program of China(2021YFA1501700)the National Natural Science Foundation of China(22272114)+2 种基金the Funding for Hundred Talent Program(20822041E4079)the Fundamental Research Funds from Sichuan University(2022SCUNL103)This work has also been supported by SINOPEC Research Institute of Petroleum Processing Co.,Ltd.via collaborative project No.36800000-24-ZC0607-0175.
文摘Converting waste plastics directly into valuable aromatic chemicals is a promising,cost-effective recycling strategy.Traditional zeolite-catalyzed cracking of polyolefins to produce aromatics often needs high temperatures and faces issues like low selectivity for liquid aromatics,separation difficulties,and rapid catalyst deactivation due to coking.To address this,a multifunctional Ni/HZSM-5 catalyst was developed to efficiently upgrade various polyolefins—including polyvinyl chloride—into gaseous alkanes(C_(1)–C_(5))and easily separable liquid aromatics(C_(6)–C_(12))at 400°C,without added solvents or hydrogen.Aromatic products make up 57.1 wt%of total output,with more than 97.8%selectivity for the liquid phase and a BTX(benzene,toluene,and xylene)selectivity of 76.1%.The high activity and selectivity for aromatics stem from synergistic interactions between Ni nanoparticles(NPs)and acid sites in the zeolite,which promote selective C–C bond breaking and control hydrogenolysis and aromatization pathways.This synergy allows precise control over the distribution of products by carbon number and favors the formation of separable aromatics.Notably,the catalyst also prevents coking by hydrogenolyzing and hydrogenating reactive intermediates before they form stable graphite-like deposits.Consequently,Ni/ZSM-5 catalyst demonstrates excellent stability,maintaining consistent aromatics yield over 13 consecutive cycles and processing over 30 times its weight in plastics without regeneration.After regeneration,the activity of the catalyst was fully restored,highlighting its potential for industrial use.This work offers valuable insights for designing durable,high-activity catalysts,providing a practical route to improve plastic recycling technologies.
基金supported by the National Natural Science Foundation of China(Grant 32471873)the Major Projects in Agricultural Biological Breeding(Grant 2023ZD04056)+3 种基金the National Key R&D Program of China(Grant 2023YFD1401304)the Natural Science Foundation of Jiangsu Province,China(Grants BK20221426,BK20231291)the China Postdoctoral Science Foundation project(Grant 2024M751426)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant KYCX241264)。
文摘Both genders of the dioecious gymnosperm Ginkgo bilob a have distinct practical production and application uses,so quick,accurate identification of males and females is important for early seedling breeding.To develop a fast method to identify the sexes,we used the Easy DNA extraction(EZ-D)method to extract DNA from leaves within1 min for use with the recombinase polymerase amplification-lateral flow dipstick(RPA-LFD)system and identify the sex.A portable nucleic acid detection card kit(PNADCK)was used for on-site analysis.This method facilitates rapid extraction of nucleic acids from a single and can accurately detect 100 pg/μL of G.biloba female genomic DNA within20 min at 39°C.The EZ-DRPA-LFD-PNADCK system enables precise on-site determination of G.bilob a leaf sex and is rapid,efficient,sensitive,and convenient,greatly enhancing productivity for G.biloba because seedlings with specific sex characteristics can be selected at an earlier stage,planting strategies can be optimized,and production efficiency improved.
文摘The restriction of KB averaging method is discussed and asymptotic solution of the weakly nonlinear and forced oscillation u″+ω20u=εkcos ωt-εu3 is obtained by Struble technique. The conclusion about this oscillation derived with other method is discussed. The results show that KB method will break down when a and θ in the zeroth solution of above eqation are not slowly varying functions of time t. The stationary solution of weakly nonlinear oscillation, u″+ω20u=εkcosω(ε)t-εu3 is also analysed.
基金financially supported by the Innovative Group Project of China (21621004)Demonstration Project of Integration of Science, Education and Industry in Qilu University of Technology (2020KJC-ZD09)
文摘In this study,the solid structure,dissolution behavior,thermodynamic properties and nucleation kinetics of malonamide were explored.Firstly,the Hirshfeld surface analysis and molecular electrostatic potential surface were plotted to reveal the percentage contribution of various intermolecular contacts and location of the strongest hydrogen bond.Next,the solubility of malonamide in 12 solvents was determined by dynamic method at temperatures from 278.15 K to 318.15 K.Four thermodynamic models were applied to analyze solubility results.In addition,the thermodynamic properties were calculated to further analyze and discuss the dissolution behavior of malonamide.Moreover,the physicochemical properties of solvents were explored to express the solvent effects.The results illustrate“like dissolves like”,“mass transfer”and“solvent–solute interaction”rules play the synergistic effects on the dissolution process.The molecular dynamic simulation,including radial distribution function analysis and solvent free energy,was used to further explain the dissolution behavior.At last,the nucleation rate and effective interfacial energy in methanol solvent was measured and calculated to reveal the nucleation behaviour.
基金supported by the National Natural Science Foundation of China(No.41905108)the National Research Program for Key Issues in Air Pollution Control(No.DQ GG0532).
文摘To study the volatile organic compounds(VOCs)emission characteristics of industrial enterprises in China,6 typical chemical industries in Yuncheng City were selected as research objects,including the modern coal chemical industry(MCC),pharmaceutical industry(PM),pesticide industry(PE),coking industry(CO)and organic chemical industry(OC).The chemical composition of 91 VOCs was quantitatively analyzed.The results showed that the emission concentration of VOCs in the chemical industry ranged from 1.16 to 155.59 mg/m^(3).Alkanes were the main emission components of MCC(62.0%),PE(55.1%),and OC(58.5%).Alkenes(46.5%)were important components of PM,followed by alkanes(23.8%)and oxygenated volatile organic compounds(OVOCs)(21.2%).Halocarbons(8.6%-71.1%),OVOCs(9.7%-37.6%)and alkanes(11.2%-27.0%)were characteristic components of CO.The largest contributor to OFP was alkenes(0.6%-81.7%),followed by alkanes(9.3%-45.9%),and the lowest onewas alkyne(0%-0.5%).Aromatics(66.9%-85.4%)were the largest contributing components to SOA generation,followed by alkanes(2.6%-28.5%),and the lowest one was alkenes(0%-4.1%).Ethylene and BTEX were the key active species in various chemical industries.The human health risk assessment showed workers long-term exposed to the air in the chemical industrial zone had a high cancer and non-cancer risk during work,and BTEX and dichloromethane were the largest contributors.
基金supported by the Natural Science Foundation of Ningxia(No.2022AAC05014).
文摘In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves the electrical conductivity of the whole electrode,but also protects the inner Si nanoparticles(Si NPs)from rupturing and being damaged by undesired side reactions with the electrolyte.As a result,the Si@rGO/ZrO_(2) anode delivers high initial discharge capacity of 3046 mAh·g^(−1) at 1.0 A·g^(−1).After 100 cycles,it can be maintained at 613 mAh·g^(−1),which is much higher than that of either the pure Si NPs(31 mAh·g^(−1))or the Si@rGO(261 mAh·g^(−1)).Even at 2 A·g^(−1),it still provides superior specific capacity of 834 mAh·g^(−1),while the pure Si anode merely possesses the capacity of 41 mAh·g^(−1).Moreover,the density functional theory calculations point out that ZrO_(2) layer can effectively enhance the adsorption energy of Li+and optimize the migration paths of Li+,ensuring the electrochemical performance of Si@rGO/ZrO_(2) composite anode.Furthermore,the Li+storage mechanism and low volume expansion of Si@rGO/ZrO_(2) anode is investigated by ex-situ X-ray photoelectron spectroscopy and morphological evolution upon cycling,respectively.
基金supported by the National Natural Science Foundation of China(Nos.22202104,22279062,22232004 and 22072067)the Natural Science Foundation of Jiangsu Province(No.BK20220933)Shuangchuang Doctor Plan of Jiangsu Province(No.JSSCBS20220273).
文摘To efficiently diminish the Pt consumption while concurrently enhancing the anodic reaction kinetics,a straightforward synthesis for PtPdAg nanotrees(NTs)with exceedingly low Pt content is presented,utilizing the galvanic replacement reaction between the initially prepared PdAg NTs and Pt ions.Due to the multilevel porous tree-like structure and the incorporation of low amounts of Pt,the electrocatalytic activity and stability of PtPdAg NTs are markedly enhanced,achieving 1.65 and 1.69 A·mg^(-1)Pt+Pd for the anodic reactions of formic acid oxidation(FAOR)and methanol oxidation(MOR)within DLFCs,surpassing the performance of PdAg NTs,as well as that of commercial Pt and Pd black.Density functional theory(DFT)calculations reveal that the addition of low amounts of Pt leads to an increase in the d-band center of PtPdAg NTs and lower the COads adsorption energy to-1.23 eV,enhancing the anti-CO toxicity properties optimally.This approach offers an effective means for designing low Pt catalysts as exceptional anodic electrocatalysts for direct liquid fuel cells.
基金financially supported by Natural Science Foundation of Shandong Province(No.ZR2024QB415)。
文摘The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid(FDCA)from 5-hydroxymethylfurfural(HMF)oxidation is one of the most promising means for the production of bioplastic monomers.In this work,we constructed a novel P-doped Ni_(3)S_(2)and Ni heterojunction on nickel foam(P-Ni_(3)S_(2)/Ni/NF)using electrodeposition methods and thermal sulfuration techniques as a bifunctional catalyst for the simultaneous anodic oxidation of HMF to FDCA(HMFOR)and the cathodic hydrogen evolution reaction(HER).On one hand,the synergistic promotion of P doping and the heterojunction of Ni_(3)S_(2)and Ni accelerated electron transfer,and on the other hand,the structure of three-dimensional microsphere stacking on NF surface to form macropores enhances the exposure of catalytically active sites.The prepared P-Ni_(3)S_(2)/Ni/NF exhibited remarkable performance with high HMF conversion(99.2%),FDCA yield(98.1%),and Faraday efficiency(98.8%),and excellent stability with good product selectivity for 7 consecutive cycles,which stands at a higher level than majority of previously published electrocatalysts.Furthermore,P-Ni_(3)S_(2)/Ni/NF also shows a significant response in HER.By using HMFOR and HER as the anodic reaction and cathodic reaction,respectively,the biomass upgrading and hydrogen production can be carried out simultaneously.The synthesized P-Ni_(3)S_(2)/Ni/NF only need a voltage of 1.31V to achieve a current density of 10mA/cm^(2)in a two-electrode system of HMFOR and HER,which is much lower than that of 1.48 V in OER and HER process,thus potentially reducing the cost of this process.
基金financial supports from the National Natural Science Foundation of China (No. 51801078)the Natural Science Foundation of Jiangsu Province, China (No. BK20180986)。
文摘Mn nanoparticles(nano-Mn)were successfully synthesized and doped into MgH_(2) to improve its de/hydrogenation properties.Compared with MgH_(2),the onset desorption temperature of 10 wt.%nano-Mn modified MgH_(2) was decreased to 175℃ and 6.7,6.5 and 6.1 wt.%hydrogen could be released within 5,10 and 25 min at 300,275 and 250℃,respectively.Besides,the composite started to take up hydrogen at room temperature and absorbed 2.0 wt.%hydrogen within 30 min at low temperature of 50℃.The hydrogenation activation energy of MgH_(2) was reduced from(72.5±2.7)to(18.8±0.2)kJ/mol after doping with 10 wt.%nano-Mn.In addition,the MgH_(2)+10 wt.%nano-Mn composite exhibited superior cyclic property,maintaining 92%initial capacity after 20 cycles.
基金National Natural Science Foundation of China(30900071,30671126)
文摘Arabidopsis thaliana seedlings were cultivated in 0-500 μmol/L of extraneous cerium （Ce） for 7 d to investigate the toxicity, uptake and translocation of rare earth elements （REEs）. The results showed that Ce could be largely absorbed by the roots ofA. thaliana and translocated to the shoots. But the uptake rates of Ce by the roots were much higher than the translocation rates from roots to shoots. Ultrastructural analysis revealed that Ce was mainly distributed on the cell wall. At higher concentration, Ce could also enter cell, destroy the ultrastructure of cells and disturb the intrinsic balance of nutrient elements of A, thaliana, Addition of Ce （50-500 μmol/L） to the culture medium significantly inhibited the elongation of primary roots, decreased chlorophyll content, rosette diameter and fresh mass of plants. The damage increased with the increase of Ce concentration in culture medium, although primary root elongation, chlorophyll content, and rosette diameter were stimulated by relatively low concentration （0.5 μmol/L） of Ce. Thus, it is speculated that REEs may become a new type contamination if we don＇t well control the release of REEs into the environment.
基金funded by the National Natural Science Foundation of China (Nos. 22176014, 21777008, 21377012, and 21177012)。
文摘Particulate matter(i.e.,PM_(1.0) and PM_(2.5)),considered as the key atmospheric pollutants,exerts negative effects on visibility,global climate,and human health by associated chemical compositions.However,our understanding of PM and its chemical compositions in Beijing under the current atmospheric environment is still not complete after witnessing marked alleviation during 2013–2017.Continuous measurements can be crucial for further air quality improvement by better characterizing PM pollution and chemical compositions in Beijing.Here,we conducted simultaneous measurements on PM in Beijing during 2018–2019.Results indicate that annualmean PM_(1.0) and PM_(2.5) concentrations were 35.49±18.61μg/m^(3) and 66.58±60.17μg/m^(3),showing a positive response to emission controls.The contribution of sulfate,nitrate,and ammonium(SNA)played an enhanced role with elevated PM loading and acted as the main contributors to pollution episodes.Discrepancies observed among chemical species between PM_(1.0) and PM_(2.5) in spring suggest that sand particles trend to accumulate in the range of 1–2.5μm.Pollution episodes occurred accompanied with southerly clusters and high formation of SNA by heterogeneous reactions in summer and winter,respectively.Results from positive matrix factorization(PMF)combined with potential source contribution function(PSCF)models showed that potential areas were seasonal dependent,secondary and vehicular sources became much more important compared with previous studies in Beijing.Our study presented a continuous investigation on PM and sources origins in Beijing,which provides a better understanding for further emission control as well as a reference for other cities in developing countries.
基金financially supported by the National Natural Science Foundation of China (Grant NO.11702268)Sichuan provincial key S&T Special Projects (Grant NO.19DZX0106)
文摘Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer on the surface of the HMX was observed by scanning electron microscopy(SEM),and a series of in-depth characterization confirmed the successful generation of CS and the coreshell structure of the samples.Differential scanning calorimeter(DSC)proves that the crystal transition temperature(204℃)and high temperature decomposition exothermal temperature(284℃)of HMX@CS is almost unchanged compared with pure HMX,which means HMX and CS have good compatibility.Then,the H50 of the samples also increased continuously(16.6 cm→33.7 cm)when the CS shell content increased from 1%to 5%,indicating that the CS shell has a certain buffering performance,and CS will absorb some heat and melt under the stimulation of impact due to its low melting point,which improved impact sensitivity of HMX effectively further.Moreover,HMX@CS has excellent hydrophobic and oleophilic performance,shows excellent wettability with lipid binder,and samples with appropriate CS shell content can continue to combustion stably after covering water.This waterproof and low sensitivity coating provides a new way for the development of multifunctional energetic materials.
基金Project(2002AA6070) supported by the Hi-tech Research and Development Program of China
文摘A self-made directional solidification device was used to fabricate d 80 mm high purity aluminum ingots. SEM and AFM were used to detect the shape of grain boundaries. The orientation of the grain was studied by X-ray diffractometry. The results show that the nucleation points locate at the intersections of three adjacent grains. The lattice orientation of grains does not alter in the horizontal direction, but gradually approaches the optimum growth direction in the vertical direction during the growth process. All the grains suffer the competition and only the one whose orientation is closest to the preferred direction can occupy the final growth space.
基金This work was financially supported by the Major State Basic Besearch Development Program of China (No.2005CB623704)The authors wish to thank professors Shao B.L.and Liu A.S.(National Analysis and Testing Center for Nonferrous Metals & Electronic Materials,General Research Institute for Nonferrous Metals) for the TEM work,and Li Y.L.(Analysis and Test Center,Beijing Normal University) for SEM work.
文摘High strength Al-Zn-Mg-Cu alloys were prepared by spray deposition and casting techniques. The microstructures of the Al-Zn-Mg-Cu alloys were studied using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Secondary phases in the microstructures of the alloys prepared by spray deposition and conventional cast were examined. The results indicate that under the conventional casting condition, the microstructure of the alloy revealed the presence of coarse Al/Mg（ZnCu）2 eutectic phases, and the spray deposited process causes an obvious modification in size, morphology, and distribution of secondary phases in the microstructure as well as reduction of segregation. The superior microstructure of the spray-deposited Al-Zn-Mg-Cu alloy was attributed to the high cooling rate, and associated with the rapid solidification process.
基金financial support from the National Natural Science Foundation of China(Grant No.51801078)the Natural Science Foundation of Jiangsu Province(Grant No.BK20180986)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX19_0614)。
文摘As a promising hydrogen storage material,the practical application of magnesium is obstructed by the stable thermodynamics and sluggish kinetics.In this paper,three kinds of NiTiO3catalysts with different mole ratio of Ni to Ti were successfully synthesized and doped into nanocrystalline Mg to improve its hydrogen storage properties.Experimental results indicated that all the Mg-NiTiO3composites showed prominent hydrogen storage performance.Especially,the Mg-NiTiO3/TiO2composite could take up hydrogen at room temperature and the apparent activation energy for hydrogen absorption was dramatically decreased from 69.8±1.2(nanocrystalline Mg)k J/mol to 34.2±0.2 k J/mol.In addition,the hydrogenated sample began to release hydrogen at about 193.2℃and eventually desorbed 6.6 wt%H2.The desorption enthalpy of the hydrogenated Mg-NiTiO3-C was estimated to be 78.6±0.8 k J/mol,5.3 k J/mol lower compared to 83.9±0.7 k J/mol of nanocrystalline Mg.Besides,the sample revealed splendid cyclic stability during 20 cycles.No obvious recession occurred in the absorption and desorption kinetics and only 0.3 wt%hydrogen capacity degradation was observed.Further structural analysis demonstrates that nanosizing and catalyst doping led to a synergistic effect on the enhanced hydrogen storage performance of Mg-NiTiO3-C composite,which might serve as a reference for future design of highly effective hydrogen storage materials.
基金Funded by the Doctoral Fund of Chengdu University (2081919131)the Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province (2021CL27)the Sichuan Science and Technology Program (2023YFG0229)。
文摘OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite nanofibers is about 200 nm,the grains size is about 1-3 nm,and the fiber surface is rough.The electrochemical test results show that the heterojunction of the prepared Ni_(3)Fe/Ni_(4)S_(3)/Ni/C hybrid crystal composite nanofiber has synergistic effect with sulfide,and exhibits good electrocatalytic activity of water decomposition and OER in alkaline system.The OER electrocatalytic performance of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite electrode prepared via a heat treatment at 1000℃process was tested in 1 mol/L KOH electrolytes.The results show that the overpotential is about 298 mV,the Tafel slope is about 74 mV?dec-1,and the surface resistance is about 1.69Ω·cm^(2),at the current density of 10 mA·cm^(-2).
文摘In this study,low-field nuclear magnetic resonance(LF-NMR)was used to collect the transverse relaxation signals of camphor seeds that had been dried at different temperatures and for different durations.The transverse relaxation time of the hydrogen nucleus was obtained by SIRT(Simultaneous Iterative Reconstruction Technique)inversion,and the correlation between the moisture content on dry basis and the amplitude of NMR signal of camphor seeds sampled at different drying stages was analyzed.The results showed that water existed in three main forms strongly bound water,weakly bound water and free water in camphor seeds.During the drying process,the peak position of strongly bound water remained unchanged,but the peak positions of weakly bound water and free water fluctuated.Drying rate increased with drying temperature increasing.In addition,there was a very significant linear relationship between the total NMR signal amplitude and moisture content on dry basis,and the correlation coefficient reached 0.984 4.
基金financially supported by the National Natural Science Foundation of China(Nos.51971207,11975170 and 51801194)。
文摘Iron-chromium-aluminum(FeCrAl)alloys with different content of niobium(Nb)—0,0.4 wt%,0.8 wt%,and 1.2 wt%—were designed and prepared.All samples were then irradiated with 2.4 MeV Fe^(2+)ion to the dose of 1 and 15 displacements per atom(dpa)at 400℃.The formations of dislocation loops induced by self-ion irradiation in these alloys were investigated by transmission electron microscopy(TEM).Nano-indentation tests were used to assess the hardness and irradiation hardening of samples.For the samples before irradiation,the(Fe,Cr)_(2)(Nb,Mo)Laves phases density and the nano-indentation hardness increased with increasing Nb content of the samples.After irradiation to 1 and 15 dpa,both of a/2<111>and a<100>dislocation loops were produced but no voids orα’phase were found in all samples.With increasing Nb content of the samples,the size of dislocation loops increased first and then decreased,while the total volume number density decreased and then increased.The fraction of a<100>dislocation loops increased first and then decreased with increasing Nb content,and increased with increasing irradiation dose.Dislocation networks and the amorphization of the Laves phases were observed in the samples with irradiation dose of 15 dpa.Irradiation hardening of Nb free samples was two to four times that of Nb containing samples,and the irradiation hardening increased with increasing Nb content of Nb containing samples.The experimental results indicate that the increase of Nb content in Fe Cr Al alloys can increase the density of Laves phases,leading to the decrease of Mo content and increase of Cr content in the matrix.The competition between the two types of solutes affects the nucleation and growth of the dislocation loops.
基金Supported by the National Natural Science Foundation of China(Nos.42007332,51979137)the Natural Science Foundation of Jiangsu Province(No.20KJB610001)。
文摘Colloidal particles,heterogeneous mixture with various organic components and continuous molecular weight(MW)distribution,is omnipresent in lake sediments and substantially influence the retention,transportation,and fate of contaminants in lake ecosystem.We sampled and extracted sedimentary colloids from different ecology regions in Taihu Lake,Jiangsu,East China,in June 2020,and they were further separated into four different particle size ranges by tangent ultrafiltration,and the properties of colloids were studied in various methods,including zeta potential analysis,transmission electron micrograph images(TEM),Fourier transformation infrared(FTIR),and 3D fluorescence.Results show that the surface of the colloids is covered with organic macromolecular substances,such as humuslike substances and protein-like substances.There were significant differences in molecular weight and fraction content of colloids in the sediments from macrophyte-dominant(MD)area and algae-dominant(AD)area in the lake.Colloids from MD area are mainly composed of humic acid,protein,and fulvic acid;the content of fulvic acid is lower than that of humic acid and protein.The humic acid exists mainly in small molecular weight(10-100 kDa),protein exists in mainly large molecular weight colloids(0.45-1μm).Colloids from AD area are mainly composed of humic acid,and mainly distributed in the molecular weight(10 kDa-0.45μm).The presence of humic acid inhibits effectively the agglomeration of the colloids.Especially,the stability of colloids is closely related to the molecular weight,with low molecular weight from MD area show higher stability.The existence of humic acid in colloids increases the electrostatic repulsion between colloidal particles,which can effectively inhibit the agglomeration of colloids,thus enhancing the stability of colloids.Furthermore,both monovalent and divalent electrolytes enhance colloidal aggregation,and the low-molecular-weight(LMW)colloid fraction exhibits higher stability efficiency than the high-molecular-weight(HMW)colloidal.
基金the National Natural Science Foundation of China(No.51671197)the Strategic Priority Research Program of the Chinese Academy of Sciences XDA(No.13040502)。
文摘In order to better understand why the corrosion behavior of carbon steel exposed in Nansha atmospheric environment is very serious, the effect of sodium, potassium and magnesium chlorides deposited on carbon steel surface has been studied under atmosphere conditions by wet/dry accelerated test. The difference of corrosion behavior and surface structure in Na+, K+, and Mg2+ containing atmosphere has been investigated by thickness loss, scanning electron microscope, X-ray diffraction and electrochemical techniques. The results indicate that the thickness loss of carbon steel exposed in different metal cations containing atmospheric environment increases in the order of Na+, K+, Mg2+. The hard metal cation can promote the dissolution of the steel to a certain extent. In Mg2+ containing atmosphere, the relative content of β-FeOOH is rather higher and the protective ability index α */γ * decreases in the order of Na+, K+, Mg2+. The corrosion current density of both bare carbon steel and the rusted carbon steel increases in the order of Na+, K+, Mg2+. The polarization resistance and the charge transfer resistance decreases in the order of Na+, K+, Mg2+.
