The corrosion resistance of the micro-arc oxidation(MAO) ceramic coating on a cast Al-13Si-5Cu alloy was investigated using various electrochemical methods including electrochemical impedance spectroscopy(EIS) and pol...The corrosion resistance of the micro-arc oxidation(MAO) ceramic coating on a cast Al-13Si-5Cu alloy was investigated using various electrochemical methods including electrochemical impedance spectroscopy(EIS) and polarization curves.Microstructures of MAO ceramic coating were studied by SEM,and the influence of microscopic patterns on corrosion resistance was analyzed.The corrosion resistance of the aluminum alloy can be improved significantly by MAO process owing to increasing impedance and corrosion potential and decreasing corrosion current,and the ceramic coatings are composed of loose layer,compact layer and transition layer,which improve the corrosion resistance.The corrosin resistance is determined by the thickness of the compact layer and is not proportional to the total thickness of MAO,though the latter is one of the important factors influencing the corrosin resistance.展开更多
One of the major obstacles for the clinical use of biodegradable magnesium(Mg)-based materials is their high corrosion rate. Micro-arc oxidation(MAO) coatings on Mg alloys provide mild corrosion protection owing to th...One of the major obstacles for the clinical use of biodegradable magnesium(Mg)-based materials is their high corrosion rate. Micro-arc oxidation(MAO) coatings on Mg alloys provide mild corrosion protection owing to their porous structure. Hence, in this study a dense Mg(OH)2 film was fabricated on MAO-coated Mg alloy AZ31 in an alkaline electrolyte containing ethylenediamine tetraacetic acid disodium(EDTA-2 Na) to reinforce the protection. Surface morphology, chemical composition and growth process of the MAO/Mg(OH)2 hybrid coating were examined using field-emission scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer. Corrosion resistance of the coatings was evaluated via potentiodynamic polarization curves and hydrogen evolution tests. Results manifested that the Mg(OH)2 coating possesses a porous nano-sized structure and completely seals the micro-pores and micro-cracks of the MAO coating.The intermetallic compound of AlMn phase in the substrate plays a key role in the growth of Mg(OH)2 film. The current density of Mg(OH)2-MAO composite coating decreases three orders of magnitude in comparison with that of bare substrate, indicating excellent corrosion resistance. The Mg(OH)2-MAO composite coating is beneficial to the formation of calcium phosphate corrosion products on the surface of Mg alloy AZ31, demonstrating a great promise for orthopaedic applications.展开更多
The observation of the sparkling discharges during the micro-arc oxidation process in KOH aqueous electrolyte was achieved. The change of surface morphology was progressively observed and a plausible pore formation me...The observation of the sparkling discharges during the micro-arc oxidation process in KOH aqueous electrolyte was achieved. The change of surface morphology was progressively observed and a plausible pore formation mechanism is proposed. Cell proliferation and ALP activity of micro- arc oxidized titanium was evaluated by human body derived osteoblasts and sligtaly better than those of blasted surface.展开更多
To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
BACKGROUNDCancer stem cells(CSCs)drive recurrence and therapeutic resistance in triplenegativebreast cancer(TNBC),a highly aggressive breast cancer subtype.Intratumoralhypoxia,a common feature of solid tumors,promotes...BACKGROUNDCancer stem cells(CSCs)drive recurrence and therapeutic resistance in triplenegativebreast cancer(TNBC),a highly aggressive breast cancer subtype.Intratumoralhypoxia,a common feature of solid tumors,promotes CSCs enrichment,yet the mechanisms sustaining CSCs stemness remain poorly understood.Hypoxia-induced reactive oxygen species can oxidatively activate ataxia telangiectasiamutated(ATM)kinase(oxidized ATM,p-ATM)independently of DNA breaks.AIMTo investigate the role of hypoxia-induced oxidized ATM in sustaining TNBCCSCstemness through c-Myc-mediated regulation of one-carbon metabolism.METHODSHs578T and MDA-MB-231 TNBC cells were cultured under normoxia or hypoxia.CSC stemness was assessed by mammosphere assays and flow cytometry.ATMactivity was assessed by pharmacological inhibition(Ku60019)and short hairpinRNA knockdown.c-Myc binding to serine hydroxymethyltransferase 2(SHMT2)and methylenetetrahydrofolate dehydrogenase 2(MTHFD2)promoters was analyzedby dual-luciferase reporter assays and chromatin immunoprecipitation.NADPH/NADP+ratios were quantified,and metabolic reprogramming was profiledby liquid chromatography-tandem mass spectrometry metabolomics.RESULTSHypoxia significantly increased mammosphere formation in both Hs578T and MDA-MB-231 cells,as reflected byhigher numbers of mammospheres(Hs578T:214±18;MDA-MB-231:198±16;both P<0.01)and larger meandiameters(P<0.01).Hypoxia also elevated CD44+/CD24-cell proportions and stemness gene expression(P<0.01).Oxidized ATM was activated under hypoxia withoutγH2AX induction,confirming DNA damage independence.ATM inhibition reduced mammosphere growth and suppressed c-Myc,SHMT2,and MTHFD2.Luciferase and chromatin immunoprecipitation assays confirmed direct c-Myc binding to SHMT2 and MTHFD2promoters,while mutation of the binding sites abolished promoter activity.NADPH/NADP+ratios were significantlyelevated under hypoxia but reduced following ATM inhibition(P<0.05).Metabolomics revealed enrichmentof serine/glycine one-carbon pathways.CONCLUSIONHypoxia-induced oxidized ATM maintains TNBC-CSC stemness by promoting c-Myc-dependent upregulation ofMTHFD2 and SHMT2,linking hypoxia,redox signaling,and one-carbon metabolism.These findings suggest apotential therapeutic axis that could be exploited for TNBC treatment.展开更多
TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemi...TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemical and wear tests.The results show that additives can considerably accelerate the formation of MAO coatings.The coatings are mostly composed of rutile and anatase TiO_(2),α-Al_(2)O_(3),γ-Al_(2)O_(3),Al_(2)TiO_(5) and SiO_(2).Sodium silicate and SiO_(2) nanoparticles added to the coating can effectively reduce the size of micropores and increase its thickness,whereas SiO_(2) nanoparticles with superior physical properties can be directly deposited at the discharge channel,significantly increasing the coating's resistance to wear and corrosion.The coating with SiO_(2) nanoparticles exhibits the best overall performance,with the lowest corrosion rate and average friction coefficient of 4.095×10^(-5)mm/a and 0.30,respectively.展开更多
Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates...Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.展开更多
Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports t...Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).展开更多
The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxi...The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.展开更多
This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two exp...This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.展开更多
Enhanced mass concentrations of aromatic-derived secondary organic aerosol(SOA)are frequently observed during humid-haze events.However,the influencing mechanism of relative humidity(RH)in aromatic-derived SOA formati...Enhanced mass concentrations of aromatic-derived secondary organic aerosol(SOA)are frequently observed during humid-haze events.However,the influencing mechanism of relative humidity(RH)in aromatic-derived SOA formation remains incompletely understood.Here,the RH dependence of SOA formation in the presence of NOx was explored by a series of chamber experiments for toluene(TOL)and 1,3,5-trimethylbenzene(TMB)photooxidation.The yield of TOL SOA and TMB SOA increased by 221%and 52%with increasing RH from~8%to~70%,respectively.Analytical results from a high-resolution mass spectrometer showed that SOA constituents with high oxygen content(O/C>0.6)were more abundant in SOA formed in the~70%RH experiment.The elevated yields and O/C of SOA could be attributed to the promoted formation and particle-phase diffusivity of highly oxidized molecules.In addition,in comparison with TMB,TOL could produce more unsaturated aldehydes,which are oxidized into carboxylic acids with high O/C,leading to a more sensitive response of TOL SOA formation to the change in RH.Our work provides mechanistic insights into RH roles in aromatic SOA formation and is helpful for a better understanding of humid-haze events.展开更多
High-performance catalyst is significant for the sustainable hydrogen(H_(2))production by electrocatalytic water splitting.Optimizing porous structure and active groups of substrate can promote the interaction of subs...High-performance catalyst is significant for the sustainable hydrogen(H_(2))production by electrocatalytic water splitting.Optimizing porous structure and active groups of substrate can promote the interaction of substrate and active metal particles,enabling excellent catalytic properties and stability.Herein,the optimization strategy of delignification and 2,2,6,6-tetramethylpyperidine-1-oxyl(TEMPO)oxidization was developed to modify the porous structure and active groups of wood substrate,and Ru doped Co/CO_(2)P(Ru-Co/CO_(2)P)nanoparticles were encapsulated into the optimized wood carbon substrate(Ru-Co/CO_(2)P@TDCW)for the efficient pH-universal hydrogen evolution reaction(HER).The nanopore and carboxyl groups were produced by delignification and TEMPO oxidation,which accelerated the dispersion and deposition of Ru-Co/CO_(2)P nanoparticles.The RuCo alloy and RuCoP nanoparticles were produced with the doping of Ru,and more Ru-Co/CO_(2)P nanoparticles were anchored by the delignified and TEMPO oxidized wood carbon(TDCW).As anticipated,the Ru-Co/CO_(2)P@TDCW catalyst exhibited excellent pH-universal HER activity,and only 16.6,93,and 43 mV of overpotentials were required to deliver the current density of 50 mA cm^(-2)in alkaline,neutral,and acidic electrolytes,outperforming the noble Pt/C/TDCW catalyst significantly.In addition,Ru-Co/CO_(2)P@TDCW catalyst presented excellent stability for more than 600 h working at 100 mA cm^(-2)in alkaline solution(1.0 M KOH).Density function theory(DFT)results revealed that energy barriers for the dissociation of H_(2)O and the formation of H_(2)were decreased by the doping of Ru,and the conductivity and efficiency of electron migration were also enhanced.This work demonstrated a strategy to optimize the structure and properties of wood carbon substrate,providing a promising strategy to synthesize high-efficiency catalyst for H_(2)production.展开更多
A solar steam generator(SSG)is an effective method for solving water shortages and protecting the environment,but its evaporation rate remains limited.Herein,Ga@EOG/PVA aerogel-based SSG with excellent photothermal se...A solar steam generator(SSG)is an effective method for solving water shortages and protecting the environment,but its evaporation rate remains limited.Herein,Ga@EOG/PVA aerogel-based SSG with excellent photothermal seawater purification capabilities was prepared using liquid metal gallium(Ga),edge oxidized graphene(EOG),and polyvinyl alcohol(PVA).The‘‘nut-cake-like''structure formed by electrochemical oxidation of EOG encapsulated Ga nanoparticles enhances light absorption and heat conversion efficiency through multiple light scattering and surface plasmon resonance.Furthermore,the vertical pore structure of the aerogel mimics the xylem conduit in tree trunks,allowing rapid transmission of heat and water,thus increasing its evaporation capacity.Based on these attributes,the SSG demonstrated a light absorption rate of 98.2%and an evaporation rate of 5.13 kg.m^(-2).h^(-1)under one-sun illumination,surpassing previously reported values in the literature.Moreover,the SSG effectively treated heavy metal salts,organic dyes,wastewaters,and acidic or alkaline solutions.These findings highlight the potential effectiveness of the prepared aerogel for numerous of environmental remediation applications,especially in ensuring high water quality and safety for human consumption.展开更多
Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent f...Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent for fragrances,cosmetics,food additives,and detergents,and can also be served as a moisturizer in cosmetics,showing broad application prospects.The distribution of DPG isomers in the products synthesized from PO and PG has a significant impactΔrGΔrHΔfHθΔfGθPO+PG⇌DPG PO+DPG⇌TPG PG+PG⇌DPG+H_(2)O PG+DPG⇌TPG+H_(2)O on the quality of the products.Therefore,conducting thermodynamic calculation on the reaction of PO and PG to synthesize DPG can provide a theoretical basis for practical operations and product distribution regulation.So,in this paper,the thermodynamic parameters of PO,1,2-PG,H_(2)O,tripropylene glycol(TPG)and three isomers of DPG under different reaction conditions is calculated.Additionally,the,and lnK for four potential reactions at various reaction temperatures and pressures are calculated.By designing isodesmic reactions and combining the results of thermodynamic calculations,the and for the isomers of DPG are obtained,and the relative error is less than 7%.The results show that in the process of preparing DPG by PO and PG,when PO∶PG=1,the reaction temperature ranges from 298.15 to 413.15 K,and the pressure ranges from 101.325 to 506.625 kPa,the reactions of and are thermodynamically spontaneous.While the reactions of and are thermodynamically unspontaneous.The optimal reaction temperature and pressure are 413.15 K and 101.325 kPa.The thermodynamic stability of the three isomers is DPG1>DPG2>DPG3 under standard conditions.The accuracy of the computational results is verified through experimental design,and based on this,the factors affecting product distribution are analyzed.展开更多
Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon ...Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.展开更多
In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented...In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.展开更多
Oxidized cholesterol(OXC)is a harmful dietary substance.Although the consumption of OXC has been associated with colonic inflammation,related underlying mechanisms are still limited.We evaluated the influence of dieta...Oxidized cholesterol(OXC)is a harmful dietary substance.Although the consumption of OXC has been associated with colonic inflammation,related underlying mechanisms are still limited.We evaluated the influence of dietary OXC on gut health and ecology by applying the murine model.Results showed that the thickness of the mucus layer was significantly reduced in healthy mice treated with OXC.Short-term intake of OXC did not influence the expression of pro-inflammatory factors in healthy mice but it induced the decrease of Muc2 expression in the proximal colon,accompanied by an increase in the abundance of 2 mucusdegrading bacteria,namely Akkermansia muciniphila and Bacteroides acidifaciens.Consistently,oral exposure of OXC promoted mucus barrier erosion in dextran sulfate sodium(DSS)-induced colitis mice and facilitated bacteria infiltration in the colon.The adverse effect of OXC on mucus layer disappeared in antibiotics-treated healthy mice,suggesting that the damaging effect of OXC on the gut mucus layer was not direct and instead was mediated by causing microbiota dysbiosis.Finally,the impact of OXC on the mucus layer and colitis was partly alleviated by green tea catechins.These studies demonstrated that the OXC-induced mucus barrier damage was mainly induced by the dysregulation of gut microbiota at least in this mouse model.展开更多
It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,...It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).展开更多
As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep ...As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep understanding of its oxidative pyrolysis mechanism is crucial for addressing wax deposition in oil and gas extraction,enhancing product selectivity in cracking processes,and advancing novel clean fuel technologies.Traditional experimental methods face challenges in capturing transient free-radical reaction pathways at high temperatures,whereas molecular dynamics simulations offer a powerful approach to bridge the research gap in elucidating atomic-scale dynamic mechanisms.This database is constructed based on high-precision molecular dynamics simulations,comprising oxidative pyrolysis trajectory data for three paraffin models featuring different straight-chain hydrocarbon distributions within the temperature range of 2100-2500 K.The COMPASS force field was employed to optimize the initial structures,and the ReaxFF reactive force field was used to simulate the oxidative pyrolysis process.The database includes atomic trajectories,species evolution information,and reaction network analysis results for both heating and isothermal cracking processes,with a total data volume of approximately 141 GB(including 150000 atomic configuration frames).The data is stored in a hierarchical directory structure,supporting multi-scale oxidative pyrolysis mechanism studies and providing atomic-scale dynamic evidence for revealing carbon chain length effects and temperature sensitivity.展开更多
The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical pr...The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.展开更多
基金Project(09JK481) supported by the Special Research Plan Project of the Education Department of Shaanxi Provincethe Open Fund Item of Thin-film Technology and Optical Detection Key Laboratory of Shaanxi Province,China
文摘The corrosion resistance of the micro-arc oxidation(MAO) ceramic coating on a cast Al-13Si-5Cu alloy was investigated using various electrochemical methods including electrochemical impedance spectroscopy(EIS) and polarization curves.Microstructures of MAO ceramic coating were studied by SEM,and the influence of microscopic patterns on corrosion resistance was analyzed.The corrosion resistance of the aluminum alloy can be improved significantly by MAO process owing to increasing impedance and corrosion potential and decreasing corrosion current,and the ceramic coatings are composed of loose layer,compact layer and transition layer,which improve the corrosion resistance.The corrosin resistance is determined by the thickness of the compact layer and is not proportional to the total thickness of MAO,though the latter is one of the important factors influencing the corrosin resistance.
基金supported by the National Natural Science Foundation of China(Nos.51571134 and 51601108)the SDUST Research Fund(No.2014TDJH104)
文摘One of the major obstacles for the clinical use of biodegradable magnesium(Mg)-based materials is their high corrosion rate. Micro-arc oxidation(MAO) coatings on Mg alloys provide mild corrosion protection owing to their porous structure. Hence, in this study a dense Mg(OH)2 film was fabricated on MAO-coated Mg alloy AZ31 in an alkaline electrolyte containing ethylenediamine tetraacetic acid disodium(EDTA-2 Na) to reinforce the protection. Surface morphology, chemical composition and growth process of the MAO/Mg(OH)2 hybrid coating were examined using field-emission scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer. Corrosion resistance of the coatings was evaluated via potentiodynamic polarization curves and hydrogen evolution tests. Results manifested that the Mg(OH)2 coating possesses a porous nano-sized structure and completely seals the micro-pores and micro-cracks of the MAO coating.The intermetallic compound of AlMn phase in the substrate plays a key role in the growth of Mg(OH)2 film. The current density of Mg(OH)2-MAO composite coating decreases three orders of magnitude in comparison with that of bare substrate, indicating excellent corrosion resistance. The Mg(OH)2-MAO composite coating is beneficial to the formation of calcium phosphate corrosion products on the surface of Mg alloy AZ31, demonstrating a great promise for orthopaedic applications.
文摘The observation of the sparkling discharges during the micro-arc oxidation process in KOH aqueous electrolyte was achieved. The change of surface morphology was progressively observed and a plausible pore formation mechanism is proposed. Cell proliferation and ALP activity of micro- arc oxidized titanium was evaluated by human body derived osteoblasts and sligtaly better than those of blasted surface.
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
文摘BACKGROUNDCancer stem cells(CSCs)drive recurrence and therapeutic resistance in triplenegativebreast cancer(TNBC),a highly aggressive breast cancer subtype.Intratumoralhypoxia,a common feature of solid tumors,promotes CSCs enrichment,yet the mechanisms sustaining CSCs stemness remain poorly understood.Hypoxia-induced reactive oxygen species can oxidatively activate ataxia telangiectasiamutated(ATM)kinase(oxidized ATM,p-ATM)independently of DNA breaks.AIMTo investigate the role of hypoxia-induced oxidized ATM in sustaining TNBCCSCstemness through c-Myc-mediated regulation of one-carbon metabolism.METHODSHs578T and MDA-MB-231 TNBC cells were cultured under normoxia or hypoxia.CSC stemness was assessed by mammosphere assays and flow cytometry.ATMactivity was assessed by pharmacological inhibition(Ku60019)and short hairpinRNA knockdown.c-Myc binding to serine hydroxymethyltransferase 2(SHMT2)and methylenetetrahydrofolate dehydrogenase 2(MTHFD2)promoters was analyzedby dual-luciferase reporter assays and chromatin immunoprecipitation.NADPH/NADP+ratios were quantified,and metabolic reprogramming was profiledby liquid chromatography-tandem mass spectrometry metabolomics.RESULTSHypoxia significantly increased mammosphere formation in both Hs578T and MDA-MB-231 cells,as reflected byhigher numbers of mammospheres(Hs578T:214±18;MDA-MB-231:198±16;both P<0.01)and larger meandiameters(P<0.01).Hypoxia also elevated CD44+/CD24-cell proportions and stemness gene expression(P<0.01).Oxidized ATM was activated under hypoxia withoutγH2AX induction,confirming DNA damage independence.ATM inhibition reduced mammosphere growth and suppressed c-Myc,SHMT2,and MTHFD2.Luciferase and chromatin immunoprecipitation assays confirmed direct c-Myc binding to SHMT2 and MTHFD2promoters,while mutation of the binding sites abolished promoter activity.NADPH/NADP+ratios were significantlyelevated under hypoxia but reduced following ATM inhibition(P<0.05).Metabolomics revealed enrichmentof serine/glycine one-carbon pathways.CONCLUSIONHypoxia-induced oxidized ATM maintains TNBC-CSC stemness by promoting c-Myc-dependent upregulation ofMTHFD2 and SHMT2,linking hypoxia,redox signaling,and one-carbon metabolism.These findings suggest apotential therapeutic axis that could be exploited for TNBC treatment.
基金Sichuan Science and Technology Program(2022YFSY0018)。
文摘TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemical and wear tests.The results show that additives can considerably accelerate the formation of MAO coatings.The coatings are mostly composed of rutile and anatase TiO_(2),α-Al_(2)O_(3),γ-Al_(2)O_(3),Al_(2)TiO_(5) and SiO_(2).Sodium silicate and SiO_(2) nanoparticles added to the coating can effectively reduce the size of micropores and increase its thickness,whereas SiO_(2) nanoparticles with superior physical properties can be directly deposited at the discharge channel,significantly increasing the coating's resistance to wear and corrosion.The coating with SiO_(2) nanoparticles exhibits the best overall performance,with the lowest corrosion rate and average friction coefficient of 4.095×10^(-5)mm/a and 0.30,respectively.
基金supported by the National Natural Science Foundation of China(No.52001034)the China Postdoctoral Science Foundation(No.2023M731677)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_3032).
文摘Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.
基金supported by the National Key R&D Program of China(2021YFB3701100)the National Natural Science Foundation of China(52171101)the Fundamental Research Funds for the Central Universities(2024IAIS-QN009).
文摘Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).
基金supported by the National Natural Science Foundation of China(Nos.51977027 and 51967008)the Scientific and Technological Project of Yunnan Precious Metals Lab-oratory(Nos.YPML-2023050250 and YPML-2022050206).
文摘The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.
基金support from the National Natural Science Foundation of China (No. U1960202)the Opening Foundation from Shanghai Engineering Research Center of Hot Manufacturing, China (No. 18DZ2253400)。
文摘This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.
基金supported by the National Key Research and Development Program of China (Grant No. 2023YFC3706203)the National Natural Science Foundation of China (Grant Nos. 91644214, 22361162668, and 22406109)+1 种基金the China Postdoctoral Science Foundation (Grant No. 2024M751797)Shandong Postdoctoral Science Foundation (SDCX-ZG-202400178)
文摘Enhanced mass concentrations of aromatic-derived secondary organic aerosol(SOA)are frequently observed during humid-haze events.However,the influencing mechanism of relative humidity(RH)in aromatic-derived SOA formation remains incompletely understood.Here,the RH dependence of SOA formation in the presence of NOx was explored by a series of chamber experiments for toluene(TOL)and 1,3,5-trimethylbenzene(TMB)photooxidation.The yield of TOL SOA and TMB SOA increased by 221%and 52%with increasing RH from~8%to~70%,respectively.Analytical results from a high-resolution mass spectrometer showed that SOA constituents with high oxygen content(O/C>0.6)were more abundant in SOA formed in the~70%RH experiment.The elevated yields and O/C of SOA could be attributed to the promoted formation and particle-phase diffusivity of highly oxidized molecules.In addition,in comparison with TMB,TOL could produce more unsaturated aldehydes,which are oxidized into carboxylic acids with high O/C,leading to a more sensitive response of TOL SOA formation to the change in RH.Our work provides mechanistic insights into RH roles in aromatic SOA formation and is helpful for a better understanding of humid-haze events.
基金financially supported by the National Natural Science Foundation of China(32101452)the Research Foundation of Education Bureau of Hunan Province(22B0283)+2 种基金the Hunan Provincial Natural Science Foundation(2022JJ40865)the Talents Research Funding of Central South University of Forestry and Technology(2021YJ007)the Scientific Innovation Fund for Graduate of Central South University of Forestry and Technology(2024CX02005)。
文摘High-performance catalyst is significant for the sustainable hydrogen(H_(2))production by electrocatalytic water splitting.Optimizing porous structure and active groups of substrate can promote the interaction of substrate and active metal particles,enabling excellent catalytic properties and stability.Herein,the optimization strategy of delignification and 2,2,6,6-tetramethylpyperidine-1-oxyl(TEMPO)oxidization was developed to modify the porous structure and active groups of wood substrate,and Ru doped Co/CO_(2)P(Ru-Co/CO_(2)P)nanoparticles were encapsulated into the optimized wood carbon substrate(Ru-Co/CO_(2)P@TDCW)for the efficient pH-universal hydrogen evolution reaction(HER).The nanopore and carboxyl groups were produced by delignification and TEMPO oxidation,which accelerated the dispersion and deposition of Ru-Co/CO_(2)P nanoparticles.The RuCo alloy and RuCoP nanoparticles were produced with the doping of Ru,and more Ru-Co/CO_(2)P nanoparticles were anchored by the delignified and TEMPO oxidized wood carbon(TDCW).As anticipated,the Ru-Co/CO_(2)P@TDCW catalyst exhibited excellent pH-universal HER activity,and only 16.6,93,and 43 mV of overpotentials were required to deliver the current density of 50 mA cm^(-2)in alkaline,neutral,and acidic electrolytes,outperforming the noble Pt/C/TDCW catalyst significantly.In addition,Ru-Co/CO_(2)P@TDCW catalyst presented excellent stability for more than 600 h working at 100 mA cm^(-2)in alkaline solution(1.0 M KOH).Density function theory(DFT)results revealed that energy barriers for the dissociation of H_(2)O and the formation of H_(2)were decreased by the doping of Ru,and the conductivity and efficiency of electron migration were also enhanced.This work demonstrated a strategy to optimize the structure and properties of wood carbon substrate,providing a promising strategy to synthesize high-efficiency catalyst for H_(2)production.
基金financially supported by the National Natural Science Foundation of China(No.52403116)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(No.sklpme2024-1-27)+2 种基金Sichuan Science and Technology Program(No.MZGC20240046)the Science Foundation of Sichuan Province(No.2023NSFSC0978)the Natural Science Starting Project of SWPU(No.2023QHZ018)。
文摘A solar steam generator(SSG)is an effective method for solving water shortages and protecting the environment,but its evaporation rate remains limited.Herein,Ga@EOG/PVA aerogel-based SSG with excellent photothermal seawater purification capabilities was prepared using liquid metal gallium(Ga),edge oxidized graphene(EOG),and polyvinyl alcohol(PVA).The‘‘nut-cake-like''structure formed by electrochemical oxidation of EOG encapsulated Ga nanoparticles enhances light absorption and heat conversion efficiency through multiple light scattering and surface plasmon resonance.Furthermore,the vertical pore structure of the aerogel mimics the xylem conduit in tree trunks,allowing rapid transmission of heat and water,thus increasing its evaporation capacity.Based on these attributes,the SSG demonstrated a light absorption rate of 98.2%and an evaporation rate of 5.13 kg.m^(-2).h^(-1)under one-sun illumination,surpassing previously reported values in the literature.Moreover,the SSG effectively treated heavy metal salts,organic dyes,wastewaters,and acidic or alkaline solutions.These findings highlight the potential effectiveness of the prepared aerogel for numerous of environmental remediation applications,especially in ensuring high water quality and safety for human consumption.
基金Supported by the Natural Science Foundation of Shanxi Province(202203021221303)the Science and Technology Major Project of Shanxi Province(202005D121002)the Science and Technology Cooperation and Communication Project of Shanxi Province(202304041101016)。
文摘Propylene oxide(PO)is an important petrochemical materials used to produce downstream products such as propylene glycol(PG),polyether polyols,and dipropylene glycol(DPG).Among these,DPG is commonly used as a solvent for fragrances,cosmetics,food additives,and detergents,and can also be served as a moisturizer in cosmetics,showing broad application prospects.The distribution of DPG isomers in the products synthesized from PO and PG has a significant impactΔrGΔrHΔfHθΔfGθPO+PG⇌DPG PO+DPG⇌TPG PG+PG⇌DPG+H_(2)O PG+DPG⇌TPG+H_(2)O on the quality of the products.Therefore,conducting thermodynamic calculation on the reaction of PO and PG to synthesize DPG can provide a theoretical basis for practical operations and product distribution regulation.So,in this paper,the thermodynamic parameters of PO,1,2-PG,H_(2)O,tripropylene glycol(TPG)and three isomers of DPG under different reaction conditions is calculated.Additionally,the,and lnK for four potential reactions at various reaction temperatures and pressures are calculated.By designing isodesmic reactions and combining the results of thermodynamic calculations,the and for the isomers of DPG are obtained,and the relative error is less than 7%.The results show that in the process of preparing DPG by PO and PG,when PO∶PG=1,the reaction temperature ranges from 298.15 to 413.15 K,and the pressure ranges from 101.325 to 506.625 kPa,the reactions of and are thermodynamically spontaneous.While the reactions of and are thermodynamically unspontaneous.The optimal reaction temperature and pressure are 413.15 K and 101.325 kPa.The thermodynamic stability of the three isomers is DPG1>DPG2>DPG3 under standard conditions.The accuracy of the computational results is verified through experimental design,and based on this,the factors affecting product distribution are analyzed.
文摘Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.
基金Supported by the National Key Research and Development Program of Traditional Chinese Medicine Modernization Project,China(No.2023YFC3504000)the Science and Technology Development Project of Jilin Province,China(No.20240404043ZP)the Science and Technology Innovation Cooperation Project of Changchun Science and Technology Bureau and Chinese Academy of Sciences,China(No.23SH14)。
文摘In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.
基金supported by Hong Kong Research Grants Council General Research Fund(CUHK 14102321,14103722 and 14104923)。
文摘Oxidized cholesterol(OXC)is a harmful dietary substance.Although the consumption of OXC has been associated with colonic inflammation,related underlying mechanisms are still limited.We evaluated the influence of dietary OXC on gut health and ecology by applying the murine model.Results showed that the thickness of the mucus layer was significantly reduced in healthy mice treated with OXC.Short-term intake of OXC did not influence the expression of pro-inflammatory factors in healthy mice but it induced the decrease of Muc2 expression in the proximal colon,accompanied by an increase in the abundance of 2 mucusdegrading bacteria,namely Akkermansia muciniphila and Bacteroides acidifaciens.Consistently,oral exposure of OXC promoted mucus barrier erosion in dextran sulfate sodium(DSS)-induced colitis mice and facilitated bacteria infiltration in the colon.The adverse effect of OXC on mucus layer disappeared in antibiotics-treated healthy mice,suggesting that the damaging effect of OXC on the gut mucus layer was not direct and instead was mediated by causing microbiota dysbiosis.Finally,the impact of OXC on the mucus layer and colitis was partly alleviated by green tea catechins.These studies demonstrated that the OXC-induced mucus barrier damage was mainly induced by the dysregulation of gut microbiota at least in this mouse model.
文摘It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).
基金Supported by Natural Science Foundation of Shanxi Province (202203021221219)Research on the Construction of Scientific and Technological Innovation Think Tank of Shanxi Association for Science and Technology (KXKT202542)Planning Project under Commerce Statistical Society of China (2025STY122)。
文摘As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep understanding of its oxidative pyrolysis mechanism is crucial for addressing wax deposition in oil and gas extraction,enhancing product selectivity in cracking processes,and advancing novel clean fuel technologies.Traditional experimental methods face challenges in capturing transient free-radical reaction pathways at high temperatures,whereas molecular dynamics simulations offer a powerful approach to bridge the research gap in elucidating atomic-scale dynamic mechanisms.This database is constructed based on high-precision molecular dynamics simulations,comprising oxidative pyrolysis trajectory data for three paraffin models featuring different straight-chain hydrocarbon distributions within the temperature range of 2100-2500 K.The COMPASS force field was employed to optimize the initial structures,and the ReaxFF reactive force field was used to simulate the oxidative pyrolysis process.The database includes atomic trajectories,species evolution information,and reaction network analysis results for both heating and isothermal cracking processes,with a total data volume of approximately 141 GB(including 150000 atomic configuration frames).The data is stored in a hierarchical directory structure,supporting multi-scale oxidative pyrolysis mechanism studies and providing atomic-scale dynamic evidence for revealing carbon chain length effects and temperature sensitivity.
基金supported by the Key R&D Program of Shandong Province,China(No.2025CXGC 010412)the National Key Research and Development Program of China(No.2022YFB3709300)the National Natural Science Foundation of China(No.U21A2048).
文摘The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.
