According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model...According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model to solve two-phase flow of gas and particles in dust space with eulerian-eulerian method and eulerian-lagrangian method. Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm. Moreover, numerical simulation of dust concentration in fully mechanized caving face was carded out by using Fluent software. Finally, when in forced-exhaust ventilation circumstance, drawer type fan drum have less dust absorption, and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head, and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m. Dust are more focused on relative side（in the range about y from 0 to 2 meter） of roadway space of press-ventilated fan drum, especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration. These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.展开更多
The dominated contradiction in optimizing the performance of magnesium-air battery anode lies in the difficulty of achieving a good balance between activation and passivation during discharge process.To further reconci...The dominated contradiction in optimizing the performance of magnesium-air battery anode lies in the difficulty of achieving a good balance between activation and passivation during discharge process.To further reconcile this contradiction,two Mg-0.1Sc-0.1Y-0.1Ag anodes with different residual strain distribution through extrusion with/without annealing are fabricated.The results indicate that annealing can significantly lessen the“pseudo-anode”regions,thereby changing the dissolution mode of the matrix and achieving an effective dissolution during discharge.Additionally,p-type semiconductor characteristic of discharge productfilm could suppress the self-corrosion reaction without reducing the polarization of anode.The magnesium-air battery utilizing annealed Mg-0.1Sc-0.1Y-0.1Ag as anode achieves a synergistic improvement in specific capacity(1388.89 mA h g^(-1))and energy density(1960.42 mW h g^(-1)).This anode modification method accelerates the advancement of high efficiency and long lifespan magnesium-air batteries,offering renewable and cost-effective energy solutions for electronics and emergency equipment.展开更多
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temper...Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.展开更多
The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(...The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was the diffusion in the molten slag.The dissolution rate of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was affected by the composition and size of inclusion.The functional relationship between the dimensionless inclusion capacity(Zh)and the dimensionless dissolution rate(Ry)of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was calculated as Ry=2.10×10^(-6)Zh^(0.160),while it was Ry=2.10×10^(-6)Zh^(0.0087)for Al_(2)O_(3)-CaO complex inclusions.On this basis,the complete dissolution time and rate of the complex inclusions were calculated by using the function relation between the Zh and Ry numbers.展开更多
Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status an...Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.展开更多
The deep layer has become an important replacement field for oil and gas exploration,but the formation mechanism of effective reservoirs is unknown,and the distribution of dessert reservoirs is difficult to predict,wh...The deep layer has become an important replacement field for oil and gas exploration,but the formation mechanism of effective reservoirs is unknown,and the distribution of dessert reservoirs is difficult to predict,which seriously affects the discovery of deep resources.In this paper,the reservoir of the first and second members of the Shahejie Formation in the Caofeidian 6-4S area of the Bozhong Depression is taken as an example.Through the comprehensive means such as well-seismic calibration,denudation recovery,source-sink quantitative coupling,basin simulation,microscopic observation,X-ray diffraction,inclusion and thermodynamic analysis,the reservoir formation mechanism of dissolution pores and the favorable area distribution of thermodynamic prediction of dissolution reaction in the study area are carried out.The results show that the dissolution pores are the dominant type,accounting for more than 80%of the total pores.The dissolution reaction between soluble minerals such as feldspar accumulated in the near source and acidic fluids such as organic acids formed in the adjacent strata is the main mechanism for the development of dissolution pores.The organic matter in the adjacent strata is controlled by temperature and pressure during the burial evolution process to form organic acids,and migrates to the adjacent reservoirs for selective dissolution under the action of pressure and other driving forces.The characteristics of thermodynamic parameters(ΔG,which can determine whether feldspar is dissolved)and kinetic parameters(R,indicating the degree of feldspar dissolution)of feldspar dissolution reaction show that the thermodynamic parameters of feldspar dissolution are positively correlated with temperature,and the kinetic parameters are correlated with the concentration of organic acid discharge.The results of thermodynamic and kinetic parameters are coupled with provenance-sedimentary facies-diagenetic facies,and it is predicted that the plane area of TypeⅠfavorable area is 50 km^(2),and the plane area of TypeⅡfavorable area is 62.4 km2.This method provides theoretical reference and method guidance for the prediction of favorable reservoir distribution of deep clastic rocks,and has a good application prospect.展开更多
Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,d...Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,deteriorating the gas and liquid permeability of the burden column.This exacerbates coke degradation,significantly impacting the smelting process and increasing the demand for high-quality coke.To investigate the existence state of coke in the hearth,a 2500 m3 BF in China was taken as the research object,and three sets of samples at different heights of the hearth were obtained during planned outage.The results indicate that coke undergoes a significant degradation upon reaching the hearth.The proportion of coke particles smaller than 50 mm ranges from 81.22%to 89.50%.The proportion of coke particles larger than 20 mm decreases as the distance from the centerline of the tuyere increases,while the proportion of particles smaller than 10 mm increases with this distance.Additionally,the closer the bottom of the furnace is,the smaller the coke particle size becomes.The composition of slag filling the coke pores is similar to that of the final slag in the blast furnace,and the graphitization of coke is comparable to that of the final slag.The graphitization of coke starts from the surface of coke and leads to the formation of coke fines,and the graphitization degree of−74μm coke fines is the highest.The temperature has an effect on the reaction rate of coke solution loss,and the higher the temperature is,the faster the reaction rate is.展开更多
The gasification behaviors of coke were investigated under conditions simulating a hydrogen-rich blast furnace atmosphere,composed of N_(2),CO,CO_(2),H_(2),and H_(2)O.Systematic experimental studies were conducted to ...The gasification behaviors of coke were investigated under conditions simulating a hydrogen-rich blast furnace atmosphere,composed of N_(2),CO,CO_(2),H_(2),and H_(2)O.Systematic experimental studies were conducted to examine the effects of gasification temperature and H_(2)O content on the microstructural and macroscopic properties of coke.The results indicated that increasing temperature and H_(2)O content enhanced the gasification and dissolution loss of coke,with temperature having a more significant impact.Pore structure analysis of the gasified coke revealed that small pores and micropores predominated at 900 and 1000℃.However,at gasification temperatures above 1100℃,oversized holes formed,some of which extended into the coke's interior.The compressive strength of the coke was also assessed,showing that higher gasification temperatures or increased H_(2)O content reduced this property.This reduction is primarily due to the increased coke porosity and the degradation of the pore wall structure.X-ray diffraction analysis results suggested that higher gasification temperatures and H2O content could improve the degree of order in the carbon microcrystals of the gasified coke.展开更多
Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated u...Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.展开更多
High electrochemical performance supercapacitors require activated carbon with high specific surface area,suitable pore size distribution and surface properties,and high electrical conductivity as electrode materials,...High electrochemical performance supercapacitors require activated carbon with high specific surface area,suitable pore size distribution and surface properties,and high electrical conductivity as electrode materials,whereas there exists a trade-off relationship between specific surface area and electrical conductivity,which is not well met by a single type of carbon source.To solve this problem,the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution,followed by carbonization and KOH activation.The effects of mixing mass ratio and activation temperature on the prepared activated carbon(AC)are investigated using single factor experimental method.The experimental results show that AC_(1/3-800)has abundant micropore and mesopore content,good pore structure connectivity,high electrical conductivity and good wettability,and superior electrochemical properties compared with other activated carbons prepared in this experiment.Its total specific surface area is up to 2098.5 m^(2)·g^(-1),the pore volume is up to 1.33 cm^(3)·g^(-1),the content of mespores with diameter of 6-8 nm is significantly increased,and the pore size distribution is wide and uniform.When the current density increases from 0.1 to 10 A·g^(-1),the gravimetric capacitance decreases from 219 to 186 F·g^(-1)with a capacitance retention of 84.9%,the equivalent series resistance is very small,and the rate performance and reversibility of charging and discharging have also been excellent.展开更多
In a hydrogen-rich blast furnace,an increased coke load accentuates the support skeleton role of coke,particularly in the cohesive and dripping zones following partial dissolution with slag.To investigate the dissolut...In a hydrogen-rich blast furnace,an increased coke load accentuates the support skeleton role of coke,particularly in the cohesive and dripping zones following partial dissolution with slag.To investigate the dissolution behaviours of coke in these regions,coke samples were gasified in a N2-CO-CO_(2)-H_(2)-H_(2)O atmosphere,simulating hydrogen-rich blast furnace conditions.Subsequently,the dissolution of gasified coke with slag containing FeO was analysed.The influence of coke gasification degree and FeO concentration in slag on coke dissolution was examined.The results showed that both higher coke gasification degrees and increased FeO content accelerate coke mass loss and exacerbate surface degradation upon dissolution,while effects on the internal structure of coke remain relatively minor,especially regarding FeO concentration.Additionally,hydrogen-rich gasification raised the graphitisation level of coke,with dissolution further enhancing the graphitisation of gasified coke.展开更多
The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolat...The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolates with the attributes of P.fluorescens out of fifteen local isolates that are represented by the following codes and sequences(P.f9,P.f8,P.f6,P.f5,P.f4,P.f2,P.f1,P.f14,P.f13,P.f11).Results also confirmed the diagnosis of bacterial isolates by biochemical and molecular tests using a specialized primer to amplify the bp698 region of the 16S ribosomal RNA gene,approved by Macrogen/Korea.The test efficiency in dissolving solid phosphate by P.fluorescens bacteria showed that the most effective is the(P.f1)isolate,giving the highest score effectiveness in mineral phosphate dissolution by the diameter of the clear zone around the colony,which was effective in phosphate dissolution up to 6.95 mm.The efficiency of the Nitrogen Fixation Test showed that the isolate(P.f5)scored the highest nitrogen-fixing efficiency amount with a value of 6.81 mg L^(-1).The quantitative amount of the hormone for each of Auxins,Cytokinins,and Gibberellins was assayed;the results with isolate(P.f1)for IAA(Auxins)gave a concentration up to 28.6μg ml^(-1),which was the most,while the production of GA3 by isolate(P.f1)gave the maximum value of 36.7μg ml^(-1),and for synthesis of the hormone of Cytokinins represented by isolate(P.f2),the highest value in the production of Cytokinins hormone was recorded at 26.3μg ml^(-1).展开更多
This work investigated the original microstructure of cold-worked alumina-forming austenitic steel,along with its precipitation and dissolution corrosion behaviors in lead-bismuth eutectic with 10-8 wt.%oxygen at 600...This work investigated the original microstructure of cold-worked alumina-forming austenitic steel,along with its precipitation and dissolution corrosion behaviors in lead-bismuth eutectic with 10-8 wt.%oxygen at 600℃,using solution-annealed steel for comparison.Anomalously,cold-worked steel presented milder corrosion compared to solution-annealed steel,with average corrosion depths of 314.3 and 401.0μm after 1700 h exposure.Cold working-induced de-twinning transformed the annealing twin boundaries into normal high-angle grain boundaries(NGBs),increasing NGBs proportion from 36%to 89%.The increased NGBs provided more nucleation sites for intergranular barriers composed of alternate NiAl and M23C6 precipitates,thus better obstructing the dissolution attack.展开更多
Layered manganese dioxide(δ-MnO_(2))is a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity,high operating voltage,and low cost.However,its practical application face...Layered manganese dioxide(δ-MnO_(2))is a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity,high operating voltage,and low cost.However,its practical application faces challenges,such as low electronic conductivity,sluggish diffusion kinetics,and severe dissolution of Mn^(2+).In this study,we developed a δ-MnO_(2) coated with a 2-methylimidazole(δ-MnO_(2)@2-ML)hybrid cathode.Density functional theory(DFT)calculations indicate that 2-ML can be integrated into δ-MnO_(2) through both pre-intercalation and surface coating,with thermodynamically favorable outcomes.This modification expands the interlayer spacing of δ-MnO_(2) and generates Mn-N bonds on the surface,enhancing Zn^(2+)accommodation and diffusion kinetics as well as stabilizing surface Mn sites.The experimentally prepared δ-MnO_(2)@2-ML cathode,as predicted by DFT,features both 2-ML pre-intercalation and surface coating,providing more zinc-ion insertion sites and improved structural stability.Furthermore,X-ray diffraction shows the expanded interlayer spacing,which effectively buffers local electrostatic interactions,leading to an enhanced Zn^(2+)diffusion rate.Consequently,the optimized cathode(δ-MnO_(2)@2-ML)presents improved electrochemical performance and stability,and the fabricated AZIBs exhibit a high specific capacity(309.5mAh/g at 0.1 A/g),superior multiplicative performance(137.6mAh/g at 1 A/g),and impressive capacity retention(80%after 1350 cycles at 1 A/g).These results surpass the performance of most manganese-based and vanadium-based cathode materials reported to date.This dual-modulation strategy,combining interlayer engineering and interface optimization,offers a straightforward and scalable approach,potentially advancing the commercial viability of low-cost,high-performance AZIBs.展开更多
In Switzerland,the Opalinus Clay has been selected as a potential host rock for the deep geological disposal of radioactive waste due to its low hydraulic conductivity and favorable swelling properties.During the oper...In Switzerland,the Opalinus Clay has been selected as a potential host rock for the deep geological disposal of radioactive waste due to its low hydraulic conductivity and favorable swelling properties.During the operational phase of the repository,the host rock will be exposed to pH values as high as 13.5 due to concrete degradation,which will certainly affect its hydraulic properties.This study investigates the effect of pH increase on the water retention properties of Opalinus Clay.A series of samples from the lower sandy facies of the Mont Terri site in Switzerland,at initial dry state,were exposed to a hyperalkaline solution of pH=13.5 and to the synthetic water of pH=7.5 at different water contents.After equilibrium,the total suction was measured with a dew point potentiometer and microstructural analyses were conducted via mercury intrusion porosimetry(MIP)and nitrogen adsorption-desorption technique.It was found that the total suction decreased with hydration and pH increase.Since the two investigated solutions have the same osmotic suction,the decrease in total suction was attributed to the decrease in matric suction.Indeed,the total porosity increased with saturation and pH increase.This was confirmed by MIP data that evidenced an increase in the proportion of macropores,and by Barret eJoynereHalenda(BJH)data that showed mesopore generation.The specific surface area(SSA)also increased.The previous results were due to mineral hydration and,exclusively in the case of alkaline solution,to(1)the dissolution of quartz and calcite and(2)the acid-base reactions,which were concentrated at the edges of the clay particles,leading to an increase in negatively charged groups and thus to a face-to-face association of the clay particles(dispersion),causing an increase in the repulsive forces between the clay particles.In addition,the weakening of covalent bonds led to the primary dissolution of clay minerals,i.e.silicon and aluminum detachment.展开更多
Magnesium implants have received widespread attention in orthopaedic surgery.However,the mechanical degradation and concurrent inflammation caused by the rapid corrosion of Mg limits their applications.In this study,a...Magnesium implants have received widespread attention in orthopaedic surgery.However,the mechanical degradation and concurrent inflammation caused by the rapid corrosion of Mg limits their applications.In this study,a kind of unique core-shell heterojunction CuS@PPy nanostructures was synthesized and then incorporated in polycaprolactone(PCL)to construct an intelligent coating(CuS@PPy/PCL)on micro-arc-oxidized Mg implants.The PCL-based coating can realize near-infrared(NIR)-driven antibacterial and controllable Mg dissolution according to different bone healing stages.At the beginning of bone remodelling,the coating exhibits promising antibacterial properties with 99.67%and 99.17%efficacy against S.aureus and E.coli,respectively,thanks to the singlet oxygen(^(1)O_(2))and alkoxyl radicals(RO·)generated by the photodynamic effect of CuS@PPy heterojunction under low-power NIR light(1.5 W/cm^(2)).In the bone reparative stage,the PCL-based coating can maintain high corrosion resistance to meet the mechanical requirements of Mg implants in human body fluid.However,after the complete rehabilitation of bones,through a high-power(2 W/cm^(2))NIR light,the PCL-based coating changed from an elastic to a viscous flow state(44.7℃)under the photothermal effects of CuS@PPy,leading to quick degradation of the PCL-based coating and following accelerating dissolution of the Mg implant(avoiding secondary surgery).Hopefully,this NIR-responsive coating may provide an innovative method for the antibacterial and controllable dissolution of Mg implants.展开更多
The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditi...The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditions(3.2×10^(−4)wt.%).Advanced characterization techniques were employed to under-stand the thermodynamic and kinetic mechanisms of enhanced oxidation properties of the modified T91 steel.The results indicate that the oxidation resistance of the materials follows this order:T91<T91-Al<T91-Si.Noteworthy,the oxidation resistance of T91-Si material exhibited minimal correlation with dissolved oxygen.Under oxygen-controlled conditions,the oxide film of T91 and T91-Al was attacked and broken by LBE,with the former eventually peeling off.In contrast,both materials showed significant ox-ide film thickening,except T91-Si under oxygen-saturated conditions.The addition of Al improved the quality of the inner oxide film on T91-Al by generating Al_(2)O_(3),thereby slowing down the diffusion of Fe from the matrix and enhancing oxidation resistance.Conversely,Si actively participated in the oxidation process of T91-Si,slowing down the diffusion of Fe,and facilitating the diffusion of Cr,thereby strength-ening the oxide film protection.Consequently,the oxide thickness of T91-Si material was only 24%of T91 and 35%of T91-Al under saturated oxygen conditions.展开更多
Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and e...Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and exploring Mg alloy with good SCC resistance for wide biomedical applications.In this work,the as-cast and as-extruded Mg-3Gd-1Zn-0.4Zr(GZ31K)alloys with uniform corrosion were used to investigate SCC behavior.The as-extruded GZ31K alloy exhibited better corrosion resistance and mechanical properties than the as-cast one mainly owing to grain refinement and uniformly distributed fine precipitates,and possessed superior SCC resistance.To clarify the SCC mechanism,the slow strain rate tests were assisted with applied constant potentials via an electrochemical workstation.Accelerated anodic dissolution at anodic polarization deteriorated SCC resistance due to the initiation of corrosion pits and micro-cracks.However,cathodic polarization had no obvious effects on SCC resistance,along with both retarded corrosion and accelerated hydrogen evolution.Stacking faults in GZ31K alloy were hydrogen capture containers to reduce the effect of hydrogen on SCC resistance during cathodic polarization.These findings provide new insights into the evaluation of SCC mechanism,and offer more opportunities to explore Mg alloys with good SCC resistance by regulating anodic dissolution.展开更多
Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution ...Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution of carbonate rocks by acidic fluids is conducive to the development of secondary pore space in reservoirs.In contrast,the free drift experiment based on water bath instrument can simulate the dissolution process of carbonate rocks in shallow burial environment effectively.In order to study the shallow burial dissolution mechanism of carbonate rocks in different acid solutions,14 samples of typical carbonate rocks of Sinian,Cambrian,Ordovician,Permian and Triassic ages in the Tarim and Sichuan basins,China were used.The dissolution experiments on carbonate rocks in sulfuric acid,acetic acid,hydrochloric acid,silicic acid and carbonic acid at shallow burial temperature(30℃≤T≤90℃)were carried out using a water bath instrument.The PHREEQC software was used to simulate the dissolution of carbonate minerals,in order to compare the results of constant temperature water bath experiment.The results show that acid solutions have significant dissolution effect on shallow burial carbonate rocks when T=50–60℃,which corresponds to the burial depth of 1500–2000 m in the Tarim Basin and 1110–1480 m in the Sichuan Basin.However,there were obvious differences in the dissolution and reformation of carbonate rocks in different acids.In particular,sulfuric acid solution produced by thermochemical sulfate reduction can significantly promote the dissolution of carbonate rocks,especially dolomitic limestone.Moreover,the dissolution of limestone reservoirs is stronger than that of dolomite reservoirs in shallow burial.The results will provide new insights into the study of dissolution laws and influencing factors of reservoir spaces and the evaluation and prediction of carbonate reservoirs in China.展开更多
This study proposes a low-energy pulse current(LEPC)rapid solution treatment method,which can dis-solve more primaryγ'phase in a shorter time and effectively suppress abnormal grain growth,thereby successfully ac...This study proposes a low-energy pulse current(LEPC)rapid solution treatment method,which can dis-solve more primaryγ'phase in a shorter time and effectively suppress abnormal grain growth,thereby successfully achieving microstructure optimization and property enhancement.The microstructure anal-ysis showed that,compared with the 62.5%dissolution rate of the standard traditional solution treat-ment(1100℃/4 h),LEPC achieved an 88.9%dissolution of the primaryγ'phase in just 5 min at the same temperature.Furthermore,due to the rapidity of the LEPC treatment and its“targeted dissolution effect”on theγ'phase,excessivegrain growthwas effectivelysuppressed,resultingingrain sizecom-parable to those obtained with traditional solution treatment.Mechanical property testing indicated that the alloy treated with LEPC had a hardness of 531 HV at room temperature,while the yield strength,Ultimate strength,and maximum strain reached 994 MPa,1030 MPa,and 5.1%at the service tempera-ture(750℃).Compared to the standard traditional solution treatment,these properties were improved by 10.4%,11.1%,10.4%,and 17.5%,respectively.Finally,theoretical calculations revealed that the non-thermal effect of LEPC reduced the dissolution-free energy by approximately 49.4 kJ/mol and increased the diffusion coefficient by about 76 times,which was the fundamental reason for the accelerated disso-lution of the primaryγ’phase.展开更多
基金Supported by the National Natural Science Foundation of China （51074100） the National Natural Science Foundation of Shan dong province （ZR2OIOEM016）
文摘According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model to solve two-phase flow of gas and particles in dust space with eulerian-eulerian method and eulerian-lagrangian method. Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm. Moreover, numerical simulation of dust concentration in fully mechanized caving face was carded out by using Fluent software. Finally, when in forced-exhaust ventilation circumstance, drawer type fan drum have less dust absorption, and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head, and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m. Dust are more focused on relative side（in the range about y from 0 to 2 meter） of roadway space of press-ventilated fan drum, especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration. These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.
基金the National Natural Science:Foundation of China(52375370)the Open Project of Salt Lake Chemical Engineering Research Complex,Qinghai University(2023-DXSSKF-Z02)+2 种基金the Nat-ural Science Foundation of Shanxi(202103021224049)GDAS Projects of International cooperation platform of Sci-ence and Technology(2022GDASZH-2022010203-003)Guangdong province Science and Technology Plan Projects(2023B1212060045).
文摘The dominated contradiction in optimizing the performance of magnesium-air battery anode lies in the difficulty of achieving a good balance between activation and passivation during discharge process.To further reconcile this contradiction,two Mg-0.1Sc-0.1Y-0.1Ag anodes with different residual strain distribution through extrusion with/without annealing are fabricated.The results indicate that annealing can significantly lessen the“pseudo-anode”regions,thereby changing the dissolution mode of the matrix and achieving an effective dissolution during discharge.Additionally,p-type semiconductor characteristic of discharge productfilm could suppress the self-corrosion reaction without reducing the polarization of anode.The magnesium-air battery utilizing annealed Mg-0.1Sc-0.1Y-0.1Ag as anode achieves a synergistic improvement in specific capacity(1388.89 mA h g^(-1))and energy density(1960.42 mW h g^(-1)).This anode modification method accelerates the advancement of high efficiency and long lifespan magnesium-air batteries,offering renewable and cost-effective energy solutions for electronics and emergency equipment.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2062)supported by the Key Laboratory for Carbonate Reservoirs of China National Petroleum Corporation。
文摘Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.
基金support from the National Key R&D Program(No.2023YFB3709900)the National Natural Science Foundation of China(Grant No.U22A20171)+1 种基金the High Steel Center at the North China University of Technologythe University of Science and Technology Beijing,China.
文摘The dissolution behavior of complex inclusions in refining slag was studied using confocal laser scanning microscope.Based on the dissolution curve of complex inclusions,the main rate-limiting link of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was the diffusion in the molten slag.The dissolution rate of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was affected by the composition and size of inclusion.The functional relationship between the dimensionless inclusion capacity(Zh)and the dimensionless dissolution rate(Ry)of CaO-SiO_(2)-Al_(2)O_(3)complex inclusions was calculated as Ry=2.10×10^(-6)Zh^(0.160),while it was Ry=2.10×10^(-6)Zh^(0.0087)for Al_(2)O_(3)-CaO complex inclusions.On this basis,the complete dissolution time and rate of the complex inclusions were calculated by using the function relation between the Zh and Ry numbers.
基金Supported by the National Key Research and Development Program of China(Nos.2021YFC3100500,2022YFC3103602,2021YFF0502800)the National Natural Science Foundation of China(No.U23A2035)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2023B1212060047)the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences(No.LTO1919)the Visiting Fellowship Program of the State Key Laboratory of Marine Environmental Science,Xiamen University(No.MELRS1914)the Hainan Province Key R&D Program(No.ZDYF2023SHFZ131)。
文摘Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.
基金The National Natural Science Foundation of China under contract Nos U24B2016 and 42202157the National Basic Research Program of China under contract No. KJGG2022-0101+1 种基金the Key Laboratory of Tectonics and Petroleum Resources under contract No. TPR-2023-04CNOOC Technology Project under contract No. KJZH-2023-2105
文摘The deep layer has become an important replacement field for oil and gas exploration,but the formation mechanism of effective reservoirs is unknown,and the distribution of dessert reservoirs is difficult to predict,which seriously affects the discovery of deep resources.In this paper,the reservoir of the first and second members of the Shahejie Formation in the Caofeidian 6-4S area of the Bozhong Depression is taken as an example.Through the comprehensive means such as well-seismic calibration,denudation recovery,source-sink quantitative coupling,basin simulation,microscopic observation,X-ray diffraction,inclusion and thermodynamic analysis,the reservoir formation mechanism of dissolution pores and the favorable area distribution of thermodynamic prediction of dissolution reaction in the study area are carried out.The results show that the dissolution pores are the dominant type,accounting for more than 80%of the total pores.The dissolution reaction between soluble minerals such as feldspar accumulated in the near source and acidic fluids such as organic acids formed in the adjacent strata is the main mechanism for the development of dissolution pores.The organic matter in the adjacent strata is controlled by temperature and pressure during the burial evolution process to form organic acids,and migrates to the adjacent reservoirs for selective dissolution under the action of pressure and other driving forces.The characteristics of thermodynamic parameters(ΔG,which can determine whether feldspar is dissolved)and kinetic parameters(R,indicating the degree of feldspar dissolution)of feldspar dissolution reaction show that the thermodynamic parameters of feldspar dissolution are positively correlated with temperature,and the kinetic parameters are correlated with the concentration of organic acid discharge.The results of thermodynamic and kinetic parameters are coupled with provenance-sedimentary facies-diagenetic facies,and it is predicted that the plane area of TypeⅠfavorable area is 50 km^(2),and the plane area of TypeⅡfavorable area is 62.4 km2.This method provides theoretical reference and method guidance for the prediction of favorable reservoir distribution of deep clastic rocks,and has a good application prospect.
基金supported by the National Natural Science Foundation of China(Grant No.U1960205)China Baowu Low Carbon Metallurgy Innovation Foundation(Grant Nos.BWLCF202101 and BWLCF202104)China Minmetals Science and Technology Special Plan Foundation(Grant No.2020ZXA01).
文摘Pursuing green,low-carbon ironmaking technology primarily aims to reduce fuel ratios,especially coke ratios.Simultaneously,the reduction in coke ratios causes the coke layer in the blast furnace(BF)to become thinner,deteriorating the gas and liquid permeability of the burden column.This exacerbates coke degradation,significantly impacting the smelting process and increasing the demand for high-quality coke.To investigate the existence state of coke in the hearth,a 2500 m3 BF in China was taken as the research object,and three sets of samples at different heights of the hearth were obtained during planned outage.The results indicate that coke undergoes a significant degradation upon reaching the hearth.The proportion of coke particles smaller than 50 mm ranges from 81.22%to 89.50%.The proportion of coke particles larger than 20 mm decreases as the distance from the centerline of the tuyere increases,while the proportion of particles smaller than 10 mm increases with this distance.Additionally,the closer the bottom of the furnace is,the smaller the coke particle size becomes.The composition of slag filling the coke pores is similar to that of the final slag in the blast furnace,and the graphitization of coke is comparable to that of the final slag.The graphitization of coke starts from the surface of coke and leads to the formation of coke fines,and the graphitization degree of−74μm coke fines is the highest.The temperature has an effect on the reaction rate of coke solution loss,and the higher the temperature is,the faster the reaction rate is.
基金the financial support provided by the National Natural Science Foundation of China(Nos.52174300 and 52404340)Natural Science Foundation of Chongqing,China(No.cstc2020jcyj-msxmX0583)+2 种基金Research Foundation of Chongqing University of Science and Technology(No.ckrc20240612)Chongqing Talent Plan Project(cstc2021ycjh-bgzxm0211)Chongqing Doctoral“Through Train”Project(No.sl202100000343).
文摘The gasification behaviors of coke were investigated under conditions simulating a hydrogen-rich blast furnace atmosphere,composed of N_(2),CO,CO_(2),H_(2),and H_(2)O.Systematic experimental studies were conducted to examine the effects of gasification temperature and H_(2)O content on the microstructural and macroscopic properties of coke.The results indicated that increasing temperature and H_(2)O content enhanced the gasification and dissolution loss of coke,with temperature having a more significant impact.Pore structure analysis of the gasified coke revealed that small pores and micropores predominated at 900 and 1000℃.However,at gasification temperatures above 1100℃,oversized holes formed,some of which extended into the coke's interior.The compressive strength of the coke was also assessed,showing that higher gasification temperatures or increased H_(2)O content reduced this property.This reduction is primarily due to the increased coke porosity and the degradation of the pore wall structure.X-ray diffraction analysis results suggested that higher gasification temperatures and H2O content could improve the degree of order in the carbon microcrystals of the gasified coke.
基金Project(GZC20233199) supported by the Postdoctoral Fellowship Program of CPSF,ChinaProject(2022YFC2105300) supported by the National Key Research and Development Program of China。
文摘Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.
基金supported by the Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of China(2023KJ122)State Grid Shandong Electric Power Company Science and Technology Project(520618240009)Doctoral Research Fund of Shandong Jianzhu University(XNBS1838).
文摘High electrochemical performance supercapacitors require activated carbon with high specific surface area,suitable pore size distribution and surface properties,and high electrical conductivity as electrode materials,whereas there exists a trade-off relationship between specific surface area and electrical conductivity,which is not well met by a single type of carbon source.To solve this problem,the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution,followed by carbonization and KOH activation.The effects of mixing mass ratio and activation temperature on the prepared activated carbon(AC)are investigated using single factor experimental method.The experimental results show that AC_(1/3-800)has abundant micropore and mesopore content,good pore structure connectivity,high electrical conductivity and good wettability,and superior electrochemical properties compared with other activated carbons prepared in this experiment.Its total specific surface area is up to 2098.5 m^(2)·g^(-1),the pore volume is up to 1.33 cm^(3)·g^(-1),the content of mespores with diameter of 6-8 nm is significantly increased,and the pore size distribution is wide and uniform.When the current density increases from 0.1 to 10 A·g^(-1),the gravimetric capacitance decreases from 219 to 186 F·g^(-1)with a capacitance retention of 84.9%,the equivalent series resistance is very small,and the rate performance and reversibility of charging and discharging have also been excellent.
基金the financial support provided by the National Natural Science Foundation of China(Nos.52174300 and 52404340)Science and Technology Innovation Key R&D Program of Chongqing,China(No.CSTB2024TIAD-STX0009)+3 种基金The Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202401507)Chongqing Talent Plan Project(cstc2021ycjh-bgzxm0211)Natural Science Foundation of Chongqing,China(No.CSTB2024NSCQ-LZX0052)Chongqing Doctoral“Through Train”Project(No.sl202100000343).
文摘In a hydrogen-rich blast furnace,an increased coke load accentuates the support skeleton role of coke,particularly in the cohesive and dripping zones following partial dissolution with slag.To investigate the dissolution behaviours of coke in these regions,coke samples were gasified in a N2-CO-CO_(2)-H_(2)-H_(2)O atmosphere,simulating hydrogen-rich blast furnace conditions.Subsequently,the dissolution of gasified coke with slag containing FeO was analysed.The influence of coke gasification degree and FeO concentration in slag on coke dissolution was examined.The results showed that both higher coke gasification degrees and increased FeO content accelerate coke mass loss and exacerbate surface degradation upon dissolution,while effects on the internal structure of coke remain relatively minor,especially regarding FeO concentration.Additionally,hydrogen-rich gasification raised the graphitisation level of coke,with dissolution further enhancing the graphitisation of gasified coke.
文摘The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolates with the attributes of P.fluorescens out of fifteen local isolates that are represented by the following codes and sequences(P.f9,P.f8,P.f6,P.f5,P.f4,P.f2,P.f1,P.f14,P.f13,P.f11).Results also confirmed the diagnosis of bacterial isolates by biochemical and molecular tests using a specialized primer to amplify the bp698 region of the 16S ribosomal RNA gene,approved by Macrogen/Korea.The test efficiency in dissolving solid phosphate by P.fluorescens bacteria showed that the most effective is the(P.f1)isolate,giving the highest score effectiveness in mineral phosphate dissolution by the diameter of the clear zone around the colony,which was effective in phosphate dissolution up to 6.95 mm.The efficiency of the Nitrogen Fixation Test showed that the isolate(P.f5)scored the highest nitrogen-fixing efficiency amount with a value of 6.81 mg L^(-1).The quantitative amount of the hormone for each of Auxins,Cytokinins,and Gibberellins was assayed;the results with isolate(P.f1)for IAA(Auxins)gave a concentration up to 28.6μg ml^(-1),which was the most,while the production of GA3 by isolate(P.f1)gave the maximum value of 36.7μg ml^(-1),and for synthesis of the hormone of Cytokinins represented by isolate(P.f2),the highest value in the production of Cytokinins hormone was recorded at 26.3μg ml^(-1).
基金supported by the Nuclear Technology R&D Program.
文摘This work investigated the original microstructure of cold-worked alumina-forming austenitic steel,along with its precipitation and dissolution corrosion behaviors in lead-bismuth eutectic with 10-8 wt.%oxygen at 600℃,using solution-annealed steel for comparison.Anomalously,cold-worked steel presented milder corrosion compared to solution-annealed steel,with average corrosion depths of 314.3 and 401.0μm after 1700 h exposure.Cold working-induced de-twinning transformed the annealing twin boundaries into normal high-angle grain boundaries(NGBs),increasing NGBs proportion from 36%to 89%.The increased NGBs provided more nucleation sites for intergranular barriers composed of alternate NiAl and M23C6 precipitates,thus better obstructing the dissolution attack.
基金supported by the the National Natural Science Foundation of China(52203303)the Shenzhen Science and Technology Program(SGDX20211123151002003 and GJHZ20220913142812025)+1 种基金the International Partnership Program of the Chinese Academy of Sciences(321GJHZ2023189FN)the SIAT International Joint Lab(E5G108).
文摘Layered manganese dioxide(δ-MnO_(2))is a promising cathode material for aqueous zinc-ion batteries(AZIBs)due to its high theoretical capacity,high operating voltage,and low cost.However,its practical application faces challenges,such as low electronic conductivity,sluggish diffusion kinetics,and severe dissolution of Mn^(2+).In this study,we developed a δ-MnO_(2) coated with a 2-methylimidazole(δ-MnO_(2)@2-ML)hybrid cathode.Density functional theory(DFT)calculations indicate that 2-ML can be integrated into δ-MnO_(2) through both pre-intercalation and surface coating,with thermodynamically favorable outcomes.This modification expands the interlayer spacing of δ-MnO_(2) and generates Mn-N bonds on the surface,enhancing Zn^(2+)accommodation and diffusion kinetics as well as stabilizing surface Mn sites.The experimentally prepared δ-MnO_(2)@2-ML cathode,as predicted by DFT,features both 2-ML pre-intercalation and surface coating,providing more zinc-ion insertion sites and improved structural stability.Furthermore,X-ray diffraction shows the expanded interlayer spacing,which effectively buffers local electrostatic interactions,leading to an enhanced Zn^(2+)diffusion rate.Consequently,the optimized cathode(δ-MnO_(2)@2-ML)presents improved electrochemical performance and stability,and the fabricated AZIBs exhibit a high specific capacity(309.5mAh/g at 0.1 A/g),superior multiplicative performance(137.6mAh/g at 1 A/g),and impressive capacity retention(80%after 1350 cycles at 1 A/g).These results surpass the performance of most manganese-based and vanadium-based cathode materials reported to date.This dual-modulation strategy,combining interlayer engineering and interface optimization,offers a straightforward and scalable approach,potentially advancing the commercial viability of low-cost,high-performance AZIBs.
文摘In Switzerland,the Opalinus Clay has been selected as a potential host rock for the deep geological disposal of radioactive waste due to its low hydraulic conductivity and favorable swelling properties.During the operational phase of the repository,the host rock will be exposed to pH values as high as 13.5 due to concrete degradation,which will certainly affect its hydraulic properties.This study investigates the effect of pH increase on the water retention properties of Opalinus Clay.A series of samples from the lower sandy facies of the Mont Terri site in Switzerland,at initial dry state,were exposed to a hyperalkaline solution of pH=13.5 and to the synthetic water of pH=7.5 at different water contents.After equilibrium,the total suction was measured with a dew point potentiometer and microstructural analyses were conducted via mercury intrusion porosimetry(MIP)and nitrogen adsorption-desorption technique.It was found that the total suction decreased with hydration and pH increase.Since the two investigated solutions have the same osmotic suction,the decrease in total suction was attributed to the decrease in matric suction.Indeed,the total porosity increased with saturation and pH increase.This was confirmed by MIP data that evidenced an increase in the proportion of macropores,and by Barret eJoynereHalenda(BJH)data that showed mesopore generation.The specific surface area(SSA)also increased.The previous results were due to mineral hydration and,exclusively in the case of alkaline solution,to(1)the dissolution of quartz and calcite and(2)the acid-base reactions,which were concentrated at the edges of the clay particles,leading to an increase in negatively charged groups and thus to a face-to-face association of the clay particles(dispersion),causing an increase in the repulsive forces between the clay particles.In addition,the weakening of covalent bonds led to the primary dissolution of clay minerals,i.e.silicon and aluminum detachment.
基金support to this work:the National Natural Science Foundation of China(grant No.50971064,No.51361004)the Innovative Foundation of HUST(grant 2017KFYXJJ164).
文摘Magnesium implants have received widespread attention in orthopaedic surgery.However,the mechanical degradation and concurrent inflammation caused by the rapid corrosion of Mg limits their applications.In this study,a kind of unique core-shell heterojunction CuS@PPy nanostructures was synthesized and then incorporated in polycaprolactone(PCL)to construct an intelligent coating(CuS@PPy/PCL)on micro-arc-oxidized Mg implants.The PCL-based coating can realize near-infrared(NIR)-driven antibacterial and controllable Mg dissolution according to different bone healing stages.At the beginning of bone remodelling,the coating exhibits promising antibacterial properties with 99.67%and 99.17%efficacy against S.aureus and E.coli,respectively,thanks to the singlet oxygen(^(1)O_(2))and alkoxyl radicals(RO·)generated by the photodynamic effect of CuS@PPy heterojunction under low-power NIR light(1.5 W/cm^(2)).In the bone reparative stage,the PCL-based coating can maintain high corrosion resistance to meet the mechanical requirements of Mg implants in human body fluid.However,after the complete rehabilitation of bones,through a high-power(2 W/cm^(2))NIR light,the PCL-based coating changed from an elastic to a viscous flow state(44.7℃)under the photothermal effects of CuS@PPy,leading to quick degradation of the PCL-based coating and following accelerating dissolution of the Mg implant(avoiding secondary surgery).Hopefully,this NIR-responsive coating may provide an innovative method for the antibacterial and controllable dissolution of Mg implants.
基金financial support from the National Key R&D Program of China(No.2020YFA0405901)the National Natural Science Foundation of China(Nos.52375155 and 51875398).
文摘The study investigated the oxidation behavior of T91 steel modified with Al(T91-Al)and Si(T91-Si)in lead-bismuth eutectic(LBE)at 450℃under oxygen-saturated conditions(10^(−7)-10^(−8)wt.%)and oxygen-controlled conditions(3.2×10^(−4)wt.%).Advanced characterization techniques were employed to under-stand the thermodynamic and kinetic mechanisms of enhanced oxidation properties of the modified T91 steel.The results indicate that the oxidation resistance of the materials follows this order:T91<T91-Al<T91-Si.Noteworthy,the oxidation resistance of T91-Si material exhibited minimal correlation with dissolved oxygen.Under oxygen-controlled conditions,the oxide film of T91 and T91-Al was attacked and broken by LBE,with the former eventually peeling off.In contrast,both materials showed significant ox-ide film thickening,except T91-Si under oxygen-saturated conditions.The addition of Al improved the quality of the inner oxide film on T91-Al by generating Al_(2)O_(3),thereby slowing down the diffusion of Fe from the matrix and enhancing oxidation resistance.Conversely,Si actively participated in the oxidation process of T91-Si,slowing down the diffusion of Fe,and facilitating the diffusion of Cr,thereby strength-ening the oxide film protection.Consequently,the oxide thickness of T91-Si material was only 24%of T91 and 35%of T91-Al under saturated oxygen conditions.
基金supported by the National Natural Science Foundation of China(52071175,52301304)the Natural Science Foundation of Jiangsu Province(BK20230704)+3 种基金the China Postdoctoral Science Foundation Funded Project(2023M731742)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(23KJB430019)the Research Fund of Nanjing Institute of Technology(YKJ202402)the Open Research Fund of Jiangsu Key Laboratory for Light Metal Alloys(LMA202401).
文摘Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and exploring Mg alloy with good SCC resistance for wide biomedical applications.In this work,the as-cast and as-extruded Mg-3Gd-1Zn-0.4Zr(GZ31K)alloys with uniform corrosion were used to investigate SCC behavior.The as-extruded GZ31K alloy exhibited better corrosion resistance and mechanical properties than the as-cast one mainly owing to grain refinement and uniformly distributed fine precipitates,and possessed superior SCC resistance.To clarify the SCC mechanism,the slow strain rate tests were assisted with applied constant potentials via an electrochemical workstation.Accelerated anodic dissolution at anodic polarization deteriorated SCC resistance due to the initiation of corrosion pits and micro-cracks.However,cathodic polarization had no obvious effects on SCC resistance,along with both retarded corrosion and accelerated hydrogen evolution.Stacking faults in GZ31K alloy were hydrogen capture containers to reduce the effect of hydrogen on SCC resistance during cathodic polarization.These findings provide new insights into the evaluation of SCC mechanism,and offer more opportunities to explore Mg alloys with good SCC resistance by regulating anodic dissolution.
基金jointly supported by the Science and Technology Development Project of PetroChina Hangzhou Institute of Petroleum Geology(No.RIPED-2020-JS-51008)the Naturacl Science Foundation of China(Nos.41872250,41802159)。
文摘Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution of carbonate rocks by acidic fluids is conducive to the development of secondary pore space in reservoirs.In contrast,the free drift experiment based on water bath instrument can simulate the dissolution process of carbonate rocks in shallow burial environment effectively.In order to study the shallow burial dissolution mechanism of carbonate rocks in different acid solutions,14 samples of typical carbonate rocks of Sinian,Cambrian,Ordovician,Permian and Triassic ages in the Tarim and Sichuan basins,China were used.The dissolution experiments on carbonate rocks in sulfuric acid,acetic acid,hydrochloric acid,silicic acid and carbonic acid at shallow burial temperature(30℃≤T≤90℃)were carried out using a water bath instrument.The PHREEQC software was used to simulate the dissolution of carbonate minerals,in order to compare the results of constant temperature water bath experiment.The results show that acid solutions have significant dissolution effect on shallow burial carbonate rocks when T=50–60℃,which corresponds to the burial depth of 1500–2000 m in the Tarim Basin and 1110–1480 m in the Sichuan Basin.However,there were obvious differences in the dissolution and reformation of carbonate rocks in different acids.In particular,sulfuric acid solution produced by thermochemical sulfate reduction can significantly promote the dissolution of carbonate rocks,especially dolomitic limestone.Moreover,the dissolution of limestone reservoirs is stronger than that of dolomite reservoirs in shallow burial.The results will provide new insights into the study of dissolution laws and influencing factors of reservoir spaces and the evaluation and prediction of carbonate reservoirs in China.
基金financially supported by the National Key R&D Program of China(Nos.2020YFA0714901 and 2020YFA0714904).
文摘This study proposes a low-energy pulse current(LEPC)rapid solution treatment method,which can dis-solve more primaryγ'phase in a shorter time and effectively suppress abnormal grain growth,thereby successfully achieving microstructure optimization and property enhancement.The microstructure anal-ysis showed that,compared with the 62.5%dissolution rate of the standard traditional solution treat-ment(1100℃/4 h),LEPC achieved an 88.9%dissolution of the primaryγ'phase in just 5 min at the same temperature.Furthermore,due to the rapidity of the LEPC treatment and its“targeted dissolution effect”on theγ'phase,excessivegrain growthwas effectivelysuppressed,resultingingrain sizecom-parable to those obtained with traditional solution treatment.Mechanical property testing indicated that the alloy treated with LEPC had a hardness of 531 HV at room temperature,while the yield strength,Ultimate strength,and maximum strain reached 994 MPa,1030 MPa,and 5.1%at the service tempera-ture(750℃).Compared to the standard traditional solution treatment,these properties were improved by 10.4%,11.1%,10.4%,and 17.5%,respectively.Finally,theoretical calculations revealed that the non-thermal effect of LEPC reduced the dissolution-free energy by approximately 49.4 kJ/mol and increased the diffusion coefficient by about 76 times,which was the fundamental reason for the accelerated disso-lution of the primaryγ’phase.
