Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defect...Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defects have been developed for the photocatalytic selective oxidation of benzylamine(BA)and thioanisole(TA)under visible light.The introduction of missing-linker defects promotes the formation of unsaturated Ce sites with a high Ce3+content.It also generates a high concentration of oxygen vacancies.In situ Fourier transform infrared spectroscopy(FTIR)results revealed that BA and TA molecules were activated on coordinatively unsaturated Ce sites via the H-N…Ce and the C-S…Ce interactions,respectively.Simulated in situ electron paramagnetic resonance(EPR)data indicate that O_(2) activation and reduction occur at coordinatively unsaturated Ce^(3+)sites to form·O_(2)^(-).This is accelerated by the Ce^(3+)/Ce^(4+)redox cycle associated with the photogenerated electrons.The corresponding photogenerated holes are involved in the deprotonation of the activated BA and TA.The most active sample exhibits 98.4%and 95.5%conversion rates for BA and TA oxidation.Mechanisms for the molecular activation are proposed at the molecular level.展开更多
Photocatalysis is a promising technology for purification of indoor air by oxidation of volatile organic compounds.This study provides a comprehensive analysis of the adsorption and photo-oxidation of surface-adsorbed...Photocatalysis is a promising technology for purification of indoor air by oxidation of volatile organic compounds.This study provides a comprehensive analysis of the adsorption and photo-oxidation of surface-adsorbed acetone on three SrTiO_(3)morphologies:cubes(for which exclusively{100}facets are exposed),{110}-truncated cubes,and{100}-truncated rhombic dodecahedrons,respectively,all prepared by hydrothermal synthesis.In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy shows that cubic crystals contain a high quantity of surface-OH groups,enabling significant quantities of adsorbed acetone in the form ofη^(1)-enolate when exposed to gas phase acetone.Contrary,{110}facets exhibit fewer surface-OH groups,resulting in relatively small quantities of adsorbedη^(1)-acetone,without observable quantities of enolate.Interestingly,acetate and formate signatures appear in the spectra of cubic,surfaceη^(1)-enolate containing,SrTiO_(3)upon illumination,while besides acetate and formate,the formation of(surface)formaldehyde was observed on truncated cubes,and dodecahedrons,by conversion of adsorbedη^(1)-acetone.Time-Resolved Photoluminescence studies demonstrate that the lifetimes of photogenerated charge carriers vary with crystal morphology.The shortest carrier lifetime(τ_(1)=33±0.1 ps)was observed in{110}-truncated cube SrTiO_(3),likely due to a relatively strong built-in electric field promoting electron transport to{100}facets and hole transport to{110}facets.The second lifetime(τ_(2)=259±1 ps)was also the shortest for this morphology,possibly due to a higher amount of surface trap states.Our results demonstrate that SrTiO_(3)crystal morphology can be tuned to optimize performance in photocatalytic oxidation.展开更多
Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exc...Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exceeding 90%and a space-time yield of 715 g_(AC)g_(AU)^(-1)h^(-1)at 225℃,outperforming reported catalysts.The outstanding performance is attributed to adjacent Cu^(+)and Mn^(2+)ions in the perovskite surface,which,together with nearby AuNPs,contribute to the high activity and stability.The best-performing catalyst contains a Cu/Mn ratio of 1/3 in the perovskite.Doping too much Cu into the perovskite leads to metallic Cu,suppressing catalyst performance.Density functional theory(reaction energetics,electronic structure analysis)and microkinetics simulations aided in understanding the synergy between Cu and Mn and the role of AuNPs.The reaction involves two H abstraction steps:(1)O-H cleavage of adsorbed ethanol by the basic perovskite lattice oxygen atom and(2)α-C-H cleavage by AuNPs,yielding AC and adsorbed water.Molecular O_(2)adsorbs in the oxygen vacancy(O_(V))formed by water removal,generating a peroxide anion(O_(2)^(2-))as the activated oxygen species.In the second part of the catalytic cycle,the basic O_(2)^(2-)species abstracts the H atom from another ethanol molecule,followed byα-C-H cleavage by AuNPs,AC production,and water removal.Water formation in the second part of the catalytic cycle is the rate-controlling step for Au/LaMnO_(3)and Au/LaMnCuO_(3)models.Moderate Cu doping enhances the essential Cu^(+)-OV-Mn^(2+)sites and lowers the barrier for water formation due to the weaker Cu-O bond than the Mn-O bond.In contrast,excessive Cu doping creates unstable Cu^(2+)-O-Cu^(2+)sites and shifts the barrier to theα-C-H cleavage.展开更多
Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is r...Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is regarded as a promising process depending on the superior electron transfer and visible light utilization of photocatalyst.Herein,the nonstoichiometry MoO_(3-x)with outstanding photoresponse ability is prepared and modified by imidazole-based ionic liquid[C_(12)mim]Cl to upgrade electronic structure.The interface H-bonding between MoO_(3-x)and[C_(12)mim]Cl regard as electronic transfer channel and the recombination of e^(-)-h^(+)pairs is effectively inhibited with the modification of[C_(12)mim]Cl.Deep desulfurization rate of 96.6%can be reached within 60 min and the MoO_(3-x)/[C_(12)mim]Cl(MoC_(12))photocatalyst demonstrated outstanding cyclic stability within 7 cycles in an extraction coupled photocatalytic oxidation desulfurization(ECPODS)system.The study provides a new perspective on enhancing photocatalytic desulfurization through defect engineering and surface modification.展开更多
A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher sp...A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher specific surface area,Co^(3+)/Co^(2+)ratio,and oxygen vacancy content compared to Co_(3)O_(4).As a result,it displayed better performance in CO oxidation,achieving a total conversion temperature(T100)of 96℃.Au greatly improved the catalytic efficiency of all Co_(x)Fe_(3-x)O_(4) samples,with the 0.2%Au/Co_(2)FeO_(4) catalyst achieving a further decrease in T100 to 73℃.Stability tests conducted at room temperature on the 1%Au/Co_(x)Fe_(3-x)O_(4) catalysts demonstrated a slowed deactivation rate after Fe-doping.The reaction pathway for CO oxidation catalyzed by Au/Co_(2)FeO_(4) followed the Mars-van Krevelen mechanism.展开更多
The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid...The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid(FDCA)from 5-hydroxymethylfurfural(HMF)oxidation is one of the most promising means for the production of bioplastic monomers.In this work,we constructed a novel P-doped Ni_(3)S_(2)and Ni heterojunction on nickel foam(P-Ni_(3)S_(2)/Ni/NF)using electrodeposition methods and thermal sulfuration techniques as a bifunctional catalyst for the simultaneous anodic oxidation of HMF to FDCA(HMFOR)and the cathodic hydrogen evolution reaction(HER).On one hand,the synergistic promotion of P doping and the heterojunction of Ni_(3)S_(2)and Ni accelerated electron transfer,and on the other hand,the structure of three-dimensional microsphere stacking on NF surface to form macropores enhances the exposure of catalytically active sites.The prepared P-Ni_(3)S_(2)/Ni/NF exhibited remarkable performance with high HMF conversion(99.2%),FDCA yield(98.1%),and Faraday efficiency(98.8%),and excellent stability with good product selectivity for 7 consecutive cycles,which stands at a higher level than majority of previously published electrocatalysts.Furthermore,P-Ni_(3)S_(2)/Ni/NF also shows a significant response in HER.By using HMFOR and HER as the anodic reaction and cathodic reaction,respectively,the biomass upgrading and hydrogen production can be carried out simultaneously.The synthesized P-Ni_(3)S_(2)/Ni/NF only need a voltage of 1.31V to achieve a current density of 10mA/cm^(2)in a two-electrode system of HMFOR and HER,which is much lower than that of 1.48 V in OER and HER process,thus potentially reducing the cost of this process.展开更多
Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have receive...Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning,which is strongly determined by their composition and structure.Herein,a one-spot hydrothermal method to synthesize Cu-doped Pd_(7)Te_(3)ultrathin nanowires was proposed.The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO^(*)and adsorption of OH,which refreshes the active sites quickly and thus enhances the electroactivity for MOR.Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd,Cu-doped Pd_(7)Te_(3)nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd_(7)Te_(3)nanowires and commercial Pd/C catalysts.This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts,but also helps to inspire the catalyst design in ADMFC.展开更多
Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared t...Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.展开更多
NiMo catalyst exhibits excellent catalytic performance in the electrooxidation of 5-hydroxymethylfurfural(HMF)to produce high-value 2,5-furandicarboxylic acid(FDCA).Although metallic nickel is known to undergo reconst...NiMo catalyst exhibits excellent catalytic performance in the electrooxidation of 5-hydroxymethylfurfural(HMF)to produce high-value 2,5-furandicarboxylic acid(FDCA).Although metallic nickel is known to undergo reconstruction into high-valent species during the reaction,the dynamic evolution of molybdenum components in NiMo catalyst and their mechanistic roles in catalytic reaction remain unclear.In this study,the structural evolution of NiMo alloy during HMF electrooxidation is systematically investigated.Operando analyses reveal that under anodic polarization,molybdenum undergoes oxidative dissolution in the form of MoO_(4)^(2-),concurrently driving the generation of high-valent Ni^(3+)species.Meanwhile,the dissolved MoO_(4)^(2-)re-adsorbs on the catalyst surface,forming a unique interfacial structure with Ni^(3+).Electrochemical results demonstrate that this surface structure facilitates a synergistic effect between the MoO_(4)^(2-)and high-valent Ni^(3+),enhancing the adsorption and activation of HMF molecules.Therefore,the NiMo alloy exhibits excellent catalytic performance,with a high FDCA selectivity of 99.0%.This study provides new insights into the relationship between the catalyst reconstruction process and enhancement of catalytic performance.展开更多
BACKGROUND Gastric cancer(GC)is a type of cancer which causes high cancer-related mortality.Surgical operation and systematic chemical therapies are primary choices for the treatment of GC patients with advanced stage...BACKGROUND Gastric cancer(GC)is a type of cancer which causes high cancer-related mortality.Surgical operation and systematic chemical therapies are primary choices for the treatment of GC patients with advanced stages,however,the 5-year overall survival is only around 30%.AIM To investigate the role of mesenchymal stem cell(MSC)-derived long non-coding RNAs(lncRNA)NKILA in fatty acid oxidation and chemoresistance in GC cells,mediated through the miR-485-5p/STAT3 pathway.METHODS GC cell lines(AGS and MKN45)were co-cultured with human bone marrowderived MSCs were cultured.The MSC identity was confirmed by flow cytometry(CD73,CD90,CD105>95%positive,CD34,CD45 negative).Co-culture of GC cells and MSCs was performed in Transwell plates,where MSCs were placed in the upper chamber and GC cells in the lower chamber for 72 hours.For transfections,pcDNA-NKILA vectors,shSTAT3,and miR-485-5p mimics were utilized.Colony formation,apoptosis assays(Annexin V/PI staining),sphere formation,and flow cytometry were performed to evaluate cell proliferation,stemness,and chemoresistance.qPCR was used to analyze gene expression(Sox2,Oct4,CD133,LIN28,NKILA),and Western blotting assessed protein levels of stemness markers.Luciferase reporter assays were conducted to confirm miR-485-5p/STAT3 interactions,and biotin-labeled RNA pulldown was used to assess RNA-protein binding.Fatty acid oxidation was evaluated using a CPT1 activity assay andβ-oxidation rate detection.ATP levels were measured to assess the energetic status of GC cells.Clinical GC tissue samples were collected from patients at our hospital for validation.RESULTS MSCs were found to enhance the stemness and chemoresistance of GC cells.Co-culturing MKN45 and AGS cells with MSCs significantly increased sphere-forming ability and the expression of key cancer stem cell markers(SOX2,Oct4,LIN28,CD133),indicating that MSCs promote stem-like properties.Flow cytometry confirmed an enrichment of CD44+and CD133+subpopulations in MSC-treated GC cells.Additionally,MSC co-culture reduced chemotherapy-induced apoptosis and enhanced cell proliferation,suggesting a protective role in chemotherapy resistance.MSC-derived lncRNA NKILA further promoted stemness and chemoresistance,enhancing expression of stem cell markers and protecting cells from oxaliplatin and 5-FU-induced apoptosis.MSC co-culture also induced fatty acid oxidation in GC cells,as shown by increased CPT1 activity,β-oxidation rates,and ATP levels.NKILA mediated these effects by upregulating STAT3,which was confirmed to regulate fatty acid oxidation and chemoresistance.NKILA’s interaction with miR-485-5p further promoted STAT3 expression and fatty acid oxidation,reinforcing its role in maintaining stemness and enhancing chemoresistance.CONCLUSION MSCs enhance the stemness and chemoresistance of GC cells by secreting lncRNA NKILA,which promotes fatty acid oxidation through STAT3 activation.NKILA modulates the miR-485-5p/STAT3 axis,thereby increasing energy metabolism and supporting cancer stem cell properties.Targeting NKILA or the miR-485-5p/STAT3 pathway offers potential therapeutic strategies to overcome chemoresistance in GC.展开更多
Palladium-based catalysts have long been considered the benchmark for methane combustion;however,the authentic phase of catalytic active sites remains a subject of ongoing debate.Additionally,challenges like water-poi...Palladium-based catalysts have long been considered the benchmark for methane combustion;however,the authentic phase of catalytic active sites remains a subject of ongoing debate.Additionally,challenges like water-poisoning and long-term stability need to be addressed to advance catalyst performance.Herein,we investigate Pd on Co_(3)O_(4) nanorods as a highly effective catalyst for catalytic oxidation of methane,demonstrating long-term stability and water tolerance during a 100-h continuous operation at 350℃.Comprehensive characterizations reveal the presence of an active Pd-oxygen vacancy(Ov)-cobalt interface in Pd/Co_(3)O_(4),which effectively adsorbs molecular O_(2).The absorbed oxygen species on this interface are activated and directly participate in methane combustion.Moreover,near-ambient pressure X-ray photoelectron spectroscopy demonstrates that Pd nanoparticles undergo a rapid phase transition and predominantly remain in the metallic state during the reaction.This behavior is attributed to the electronic metal-support interaction between Pd and Co_(3)O_(4).Furthermore,in situ Fourier transformed infrared spectrum reveals that under reaction conditions,HCO3*species are formed initially and subsequently transformed into formate species,indicating that the formate pathway is the dominant mechanism for CH_(4) oxidation.展开更多
H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to char...H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.展开更多
α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 ...α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 particles. Kinetic studies on the bismuth oxidation at low-temperatures were carried out by TGA method. The results show that bismuth beads should be reunited and oxidized to become irregular Bi2O3 powders. The bismuth oxidation follows shrinking core model, and its controlling mechanism varies at different reaction time. Within 0-10 min, the kinetics is controlled by chemical reaction, after that it is controlled by O2 diffusion in the solid α-Bi2O3 layer. The apparent activation energy is determined as 55.19 kJ/mol in liquid-phase oxidation.展开更多
Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and coppe...Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.展开更多
A layer of porous film containing Ca and P was prepared by the micro-arc oxidation method on the surface of a novel near β biomedical Ti-3Zr-2Sn-3Mo-25Nb alloy, and then NH2- active group was introduced to the films ...A layer of porous film containing Ca and P was prepared by the micro-arc oxidation method on the surface of a novel near β biomedical Ti-3Zr-2Sn-3Mo-25Nb alloy, and then NH2- active group was introduced to the films by activation treatment. The phase composition, surface micro-topography and elemental characteristics of the micro-arc oxidation films were investigated with XRD, SEM, EDS and XPS, and the osteoinduction of the micro-arc oxidation films was tested using the simulated body fluid immersion, the in-vitro osteoblast cultivation test and animal experiment. The results show that the oxide layer is a kind of porous ceramic intermixture and contains Ca and P. The films in the simulated body fluid can induce apatite formation, resulting in excellent bioactivity. The cell test discovers that osteoblasts can grow well on the surface of micro-arc oxidation films. And the Ti-3Zr-2Sn-3Mo-25Nb biomedical alloy coated with active porous calcium-phosphate films shows better osteoinduction in vivo.展开更多
The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the...The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.展开更多
3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was...3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.展开更多
Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the...Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.展开更多
A Ti(Al,Si)3 diffusion coating was prepared on γ-TiAl alloy by cold sprayed Al?20Si alloy coating, followed by a heat-treatment. The isothermal and cyclic oxidation tests were conducted at 900 °C for 1000 h and ...A Ti(Al,Si)3 diffusion coating was prepared on γ-TiAl alloy by cold sprayed Al?20Si alloy coating, followed by a heat-treatment. The isothermal and cyclic oxidation tests were conducted at 900 °C for 1000 h and 120 cycles to check the oxidation resistance of the coating. The microstructure and phase transformation of the coating before and after the oxidation were studied by SEM, XRD and EPMA. The results indicate that the diffusion coating shows good oxidation resistance. The mass gain of the diffusion coating is only a quarter of that of bare alloy. After oxidation, the diffusion coating is degraded into three layers: an inner TiAl2 layer, a two-phase intermediate layer composed of a Ti(Al,Si)3 matrix and Si-rich precipitates, and a porous layer because of the inter-diffusion between the coating and substrate.展开更多
A composite ceramic coating containing Y2O3-ZrO2-MgO（YSZ-MgO） was prepared on AZ91D magnesium alloy,which was immersed in Y（NO3）3 aqueous solution as pretreatment,by micro-arc oxidation（MAO） process.The morpholo...A composite ceramic coating containing Y2O3-ZrO2-MgO（YSZ-MgO） was prepared on AZ91D magnesium alloy,which was immersed in Y（NO3）3 aqueous solution as pretreatment,by micro-arc oxidation（MAO） process.The morphology,elemental and phase compositions,corrosion behavior and thermal stability of the coatings were studied by SEM,EDX,XRD,electrochemical corrosion test,high temperature oxidation and thermal shock test.The results show that the coating mainly consists of ZrO2,Y2O3,MgO,Mg2SiO4,and MgF2.Among these compounds,Y2O3 accounts for 26.7% of（Y2O3 ＋ ZrO2）.The thickness of YSZ-MgO coating is smaller than that of ZrO2-MgO coating,but its compactness and surface roughness are better than those of ZrO2-MgO coating.YSZ-MgO coating has a good corrosion resistance,and its corrosion rate in 5% NaCl aqueous solution is lower than that of ZrO2-MgO and only about 8.5% of that of AZ91D magnesium alloy.After oxidation at 410 °C,the mass gain of AZ91D magnesium alloy presents a linear increase with the oxidation time.The YSZ-MgO coating and ZrO2-MgO coating can remarkably decrease the oxidation mass gain.The oxidation mass gain of YSZ-MgO coating is lower than that of ZrO2-MgO coating,especially during a long oxidation period.The thermal shock resistance of YSZ-MgO coating is superior to ZrO2-MgO coating.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22272026 and 22272028)the 111 Project(No.D16008)Jinhong Bi thanks the Youth Talent Support Program of Fujian Province(No.00387077).
文摘Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defects have been developed for the photocatalytic selective oxidation of benzylamine(BA)and thioanisole(TA)under visible light.The introduction of missing-linker defects promotes the formation of unsaturated Ce sites with a high Ce3+content.It also generates a high concentration of oxygen vacancies.In situ Fourier transform infrared spectroscopy(FTIR)results revealed that BA and TA molecules were activated on coordinatively unsaturated Ce sites via the H-N…Ce and the C-S…Ce interactions,respectively.Simulated in situ electron paramagnetic resonance(EPR)data indicate that O_(2) activation and reduction occur at coordinatively unsaturated Ce^(3+)sites to form·O_(2)^(-).This is accelerated by the Ce^(3+)/Ce^(4+)redox cycle associated with the photogenerated electrons.The corresponding photogenerated holes are involved in the deprotonation of the activated BA and TA.The most active sample exhibits 98.4%and 95.5%conversion rates for BA and TA oxidation.Mechanisms for the molecular activation are proposed at the molecular level.
基金Advanced Research Center for Chemical Building Blocks,ARC CBBC,which is co-foundedco-financed by the Dutch Research Council(NWO)and the Netherlands Ministry of Economic Affairs and Climate Policy.
文摘Photocatalysis is a promising technology for purification of indoor air by oxidation of volatile organic compounds.This study provides a comprehensive analysis of the adsorption and photo-oxidation of surface-adsorbed acetone on three SrTiO_(3)morphologies:cubes(for which exclusively{100}facets are exposed),{110}-truncated cubes,and{100}-truncated rhombic dodecahedrons,respectively,all prepared by hydrothermal synthesis.In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy shows that cubic crystals contain a high quantity of surface-OH groups,enabling significant quantities of adsorbed acetone in the form ofη^(1)-enolate when exposed to gas phase acetone.Contrary,{110}facets exhibit fewer surface-OH groups,resulting in relatively small quantities of adsorbedη^(1)-acetone,without observable quantities of enolate.Interestingly,acetate and formate signatures appear in the spectra of cubic,surfaceη^(1)-enolate containing,SrTiO_(3)upon illumination,while besides acetate and formate,the formation of(surface)formaldehyde was observed on truncated cubes,and dodecahedrons,by conversion of adsorbedη^(1)-acetone.Time-Resolved Photoluminescence studies demonstrate that the lifetimes of photogenerated charge carriers vary with crystal morphology.The shortest carrier lifetime(τ_(1)=33±0.1 ps)was observed in{110}-truncated cube SrTiO_(3),likely due to a relatively strong built-in electric field promoting electron transport to{100}facets and hole transport to{110}facets.The second lifetime(τ_(2)=259±1 ps)was also the shortest for this morphology,possibly due to a higher amount of surface trap states.Our results demonstrate that SrTiO_(3)crystal morphology can be tuned to optimize performance in photocatalytic oxidation.
文摘Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exceeding 90%and a space-time yield of 715 g_(AC)g_(AU)^(-1)h^(-1)at 225℃,outperforming reported catalysts.The outstanding performance is attributed to adjacent Cu^(+)and Mn^(2+)ions in the perovskite surface,which,together with nearby AuNPs,contribute to the high activity and stability.The best-performing catalyst contains a Cu/Mn ratio of 1/3 in the perovskite.Doping too much Cu into the perovskite leads to metallic Cu,suppressing catalyst performance.Density functional theory(reaction energetics,electronic structure analysis)and microkinetics simulations aided in understanding the synergy between Cu and Mn and the role of AuNPs.The reaction involves two H abstraction steps:(1)O-H cleavage of adsorbed ethanol by the basic perovskite lattice oxygen atom and(2)α-C-H cleavage by AuNPs,yielding AC and adsorbed water.Molecular O_(2)adsorbs in the oxygen vacancy(O_(V))formed by water removal,generating a peroxide anion(O_(2)^(2-))as the activated oxygen species.In the second part of the catalytic cycle,the basic O_(2)^(2-)species abstracts the H atom from another ethanol molecule,followed byα-C-H cleavage by AuNPs,AC production,and water removal.Water formation in the second part of the catalytic cycle is the rate-controlling step for Au/LaMnO_(3)and Au/LaMnCuO_(3)models.Moderate Cu doping enhances the essential Cu^(+)-OV-Mn^(2+)sites and lowers the barrier for water formation due to the weaker Cu-O bond than the Mn-O bond.In contrast,excessive Cu doping creates unstable Cu^(2+)-O-Cu^(2+)sites and shifts the barrier to theα-C-H cleavage.
基金supports from National Natural Science Foundation of China(Nos.22172066,22378176)supported by State Key Laboratory of Heavy Oil Processing.Supported by Jiangsu Collaborative Innovation Center of TechnologyMaterial of Water Treatment,Suzhou University of Science and Technology.
文摘Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is regarded as a promising process depending on the superior electron transfer and visible light utilization of photocatalyst.Herein,the nonstoichiometry MoO_(3-x)with outstanding photoresponse ability is prepared and modified by imidazole-based ionic liquid[C_(12)mim]Cl to upgrade electronic structure.The interface H-bonding between MoO_(3-x)and[C_(12)mim]Cl regard as electronic transfer channel and the recombination of e^(-)-h^(+)pairs is effectively inhibited with the modification of[C_(12)mim]Cl.Deep desulfurization rate of 96.6%can be reached within 60 min and the MoO_(3-x)/[C_(12)mim]Cl(MoC_(12))photocatalyst demonstrated outstanding cyclic stability within 7 cycles in an extraction coupled photocatalytic oxidation desulfurization(ECPODS)system.The study provides a new perspective on enhancing photocatalytic desulfurization through defect engineering and surface modification.
基金supported by the Fundamental Research Program of Shanxi Province of China(202203021211103,202303021212172,202403021211196).
文摘A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher specific surface area,Co^(3+)/Co^(2+)ratio,and oxygen vacancy content compared to Co_(3)O_(4).As a result,it displayed better performance in CO oxidation,achieving a total conversion temperature(T100)of 96℃.Au greatly improved the catalytic efficiency of all Co_(x)Fe_(3-x)O_(4) samples,with the 0.2%Au/Co_(2)FeO_(4) catalyst achieving a further decrease in T100 to 73℃.Stability tests conducted at room temperature on the 1%Au/Co_(x)Fe_(3-x)O_(4) catalysts demonstrated a slowed deactivation rate after Fe-doping.The reaction pathway for CO oxidation catalyzed by Au/Co_(2)FeO_(4) followed the Mars-van Krevelen mechanism.
基金financially supported by Natural Science Foundation of Shandong Province(No.ZR2024QB415)。
文摘The biomass electrochemical oxidation coupled with hydrogen evolution reaction has received widespread attention due to its carbon-neutral and sustainable properties.The electrosynthesis of 2,5-furanodicarboxylic acid(FDCA)from 5-hydroxymethylfurfural(HMF)oxidation is one of the most promising means for the production of bioplastic monomers.In this work,we constructed a novel P-doped Ni_(3)S_(2)and Ni heterojunction on nickel foam(P-Ni_(3)S_(2)/Ni/NF)using electrodeposition methods and thermal sulfuration techniques as a bifunctional catalyst for the simultaneous anodic oxidation of HMF to FDCA(HMFOR)and the cathodic hydrogen evolution reaction(HER).On one hand,the synergistic promotion of P doping and the heterojunction of Ni_(3)S_(2)and Ni accelerated electron transfer,and on the other hand,the structure of three-dimensional microsphere stacking on NF surface to form macropores enhances the exposure of catalytically active sites.The prepared P-Ni_(3)S_(2)/Ni/NF exhibited remarkable performance with high HMF conversion(99.2%),FDCA yield(98.1%),and Faraday efficiency(98.8%),and excellent stability with good product selectivity for 7 consecutive cycles,which stands at a higher level than majority of previously published electrocatalysts.Furthermore,P-Ni_(3)S_(2)/Ni/NF also shows a significant response in HER.By using HMFOR and HER as the anodic reaction and cathodic reaction,respectively,the biomass upgrading and hydrogen production can be carried out simultaneously.The synthesized P-Ni_(3)S_(2)/Ni/NF only need a voltage of 1.31V to achieve a current density of 10mA/cm^(2)in a two-electrode system of HMFOR and HER,which is much lower than that of 1.48 V in OER and HER process,thus potentially reducing the cost of this process.
基金supported by the National Natural Science Foundation of China(Nos.22275178 and 22005285)the Fundamental Research Funds for the Central Universities(Nos.JUSRP123013 and JUSRP123015)+1 种基金performed on Hefei advanced computing centerSupercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Highly active and robust electrocatalysts for methanol oxidation reaction(MOR)are of great significance to the commercial availability of alkaline direct methanol fuel cells(ADMFC).Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning,which is strongly determined by their composition and structure.Herein,a one-spot hydrothermal method to synthesize Cu-doped Pd_(7)Te_(3)ultrathin nanowires was proposed.The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO^(*)and adsorption of OH,which refreshes the active sites quickly and thus enhances the electroactivity for MOR.Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd,Cu-doped Pd_(7)Te_(3)nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd_(7)Te_(3)nanowires and commercial Pd/C catalysts.This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts,but also helps to inspire the catalyst design in ADMFC.
文摘Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.
基金supported by the Natural Science Foundation of Guangxi Zhuang(2022JJD120011)the National Natural Science Foundation of China(22479031,22162004)the Project for Enhancing Young and Middle-aged Teacher's Research Basis Ability in Colleges of Guangxi(2025KY0040).
文摘NiMo catalyst exhibits excellent catalytic performance in the electrooxidation of 5-hydroxymethylfurfural(HMF)to produce high-value 2,5-furandicarboxylic acid(FDCA).Although metallic nickel is known to undergo reconstruction into high-valent species during the reaction,the dynamic evolution of molybdenum components in NiMo catalyst and their mechanistic roles in catalytic reaction remain unclear.In this study,the structural evolution of NiMo alloy during HMF electrooxidation is systematically investigated.Operando analyses reveal that under anodic polarization,molybdenum undergoes oxidative dissolution in the form of MoO_(4)^(2-),concurrently driving the generation of high-valent Ni^(3+)species.Meanwhile,the dissolved MoO_(4)^(2-)re-adsorbs on the catalyst surface,forming a unique interfacial structure with Ni^(3+).Electrochemical results demonstrate that this surface structure facilitates a synergistic effect between the MoO_(4)^(2-)and high-valent Ni^(3+),enhancing the adsorption and activation of HMF molecules.Therefore,the NiMo alloy exhibits excellent catalytic performance,with a high FDCA selectivity of 99.0%.This study provides new insights into the relationship between the catalyst reconstruction process and enhancement of catalytic performance.
文摘BACKGROUND Gastric cancer(GC)is a type of cancer which causes high cancer-related mortality.Surgical operation and systematic chemical therapies are primary choices for the treatment of GC patients with advanced stages,however,the 5-year overall survival is only around 30%.AIM To investigate the role of mesenchymal stem cell(MSC)-derived long non-coding RNAs(lncRNA)NKILA in fatty acid oxidation and chemoresistance in GC cells,mediated through the miR-485-5p/STAT3 pathway.METHODS GC cell lines(AGS and MKN45)were co-cultured with human bone marrowderived MSCs were cultured.The MSC identity was confirmed by flow cytometry(CD73,CD90,CD105>95%positive,CD34,CD45 negative).Co-culture of GC cells and MSCs was performed in Transwell plates,where MSCs were placed in the upper chamber and GC cells in the lower chamber for 72 hours.For transfections,pcDNA-NKILA vectors,shSTAT3,and miR-485-5p mimics were utilized.Colony formation,apoptosis assays(Annexin V/PI staining),sphere formation,and flow cytometry were performed to evaluate cell proliferation,stemness,and chemoresistance.qPCR was used to analyze gene expression(Sox2,Oct4,CD133,LIN28,NKILA),and Western blotting assessed protein levels of stemness markers.Luciferase reporter assays were conducted to confirm miR-485-5p/STAT3 interactions,and biotin-labeled RNA pulldown was used to assess RNA-protein binding.Fatty acid oxidation was evaluated using a CPT1 activity assay andβ-oxidation rate detection.ATP levels were measured to assess the energetic status of GC cells.Clinical GC tissue samples were collected from patients at our hospital for validation.RESULTS MSCs were found to enhance the stemness and chemoresistance of GC cells.Co-culturing MKN45 and AGS cells with MSCs significantly increased sphere-forming ability and the expression of key cancer stem cell markers(SOX2,Oct4,LIN28,CD133),indicating that MSCs promote stem-like properties.Flow cytometry confirmed an enrichment of CD44+and CD133+subpopulations in MSC-treated GC cells.Additionally,MSC co-culture reduced chemotherapy-induced apoptosis and enhanced cell proliferation,suggesting a protective role in chemotherapy resistance.MSC-derived lncRNA NKILA further promoted stemness and chemoresistance,enhancing expression of stem cell markers and protecting cells from oxaliplatin and 5-FU-induced apoptosis.MSC co-culture also induced fatty acid oxidation in GC cells,as shown by increased CPT1 activity,β-oxidation rates,and ATP levels.NKILA mediated these effects by upregulating STAT3,which was confirmed to regulate fatty acid oxidation and chemoresistance.NKILA’s interaction with miR-485-5p further promoted STAT3 expression and fatty acid oxidation,reinforcing its role in maintaining stemness and enhancing chemoresistance.CONCLUSION MSCs enhance the stemness and chemoresistance of GC cells by secreting lncRNA NKILA,which promotes fatty acid oxidation through STAT3 activation.NKILA modulates the miR-485-5p/STAT3 axis,thereby increasing energy metabolism and supporting cancer stem cell properties.Targeting NKILA or the miR-485-5p/STAT3 pathway offers potential therapeutic strategies to overcome chemoresistance in GC.
文摘Palladium-based catalysts have long been considered the benchmark for methane combustion;however,the authentic phase of catalytic active sites remains a subject of ongoing debate.Additionally,challenges like water-poisoning and long-term stability need to be addressed to advance catalyst performance.Herein,we investigate Pd on Co_(3)O_(4) nanorods as a highly effective catalyst for catalytic oxidation of methane,demonstrating long-term stability and water tolerance during a 100-h continuous operation at 350℃.Comprehensive characterizations reveal the presence of an active Pd-oxygen vacancy(Ov)-cobalt interface in Pd/Co_(3)O_(4),which effectively adsorbs molecular O_(2).The absorbed oxygen species on this interface are activated and directly participate in methane combustion.Moreover,near-ambient pressure X-ray photoelectron spectroscopy demonstrates that Pd nanoparticles undergo a rapid phase transition and predominantly remain in the metallic state during the reaction.This behavior is attributed to the electronic metal-support interaction between Pd and Co_(3)O_(4).Furthermore,in situ Fourier transformed infrared spectrum reveals that under reaction conditions,HCO3*species are formed initially and subsequently transformed into formate species,indicating that the formate pathway is the dominant mechanism for CH_(4) oxidation.
文摘H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.
基金Project (2006BAB02B05-04- 01/02) supported by the National Key Technologies R&D Program of China
文摘α-Bi2O3 powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi2O3 particles. Kinetic studies on the bismuth oxidation at low-temperatures were carried out by TGA method. The results show that bismuth beads should be reunited and oxidized to become irregular Bi2O3 powders. The bismuth oxidation follows shrinking core model, and its controlling mechanism varies at different reaction time. Within 0-10 min, the kinetics is controlled by chemical reaction, after that it is controlled by O2 diffusion in the solid α-Bi2O3 layer. The apparent activation energy is determined as 55.19 kJ/mol in liquid-phase oxidation.
基金National Natural Science Foundation of China (50432020)Henan Innovation Project for University Prominent Re- search Talents (2007KYCX008)+3 种基金Henan Education Department Science and Technology Project (2007430004)Henan Plan Project for College Youth Backbone TeacherHenan University of Science and Technology Major Pre-research Foundation (2005ZD003)Henan University of Science and Technology Personnel Scientific Research Foundation (of023)
文摘Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.
基金Project (2005CB623904) supported by the National Basic Research Program of ChinaProject (30770586) supported by the National Natural Science Foundation of China+1 种基金Project (31011120049) supported by the Australia-China special fund, International Science Linkages Program co-supported by the Department of Innovation, Industry, Science and Research of Australia, and the Ministry of Science and Technology and National Science Foundation of ChinaProject (2010ZDKG-96) supported by the major Subject of "13115" Programs of Shaan’xi Province, China
文摘A layer of porous film containing Ca and P was prepared by the micro-arc oxidation method on the surface of a novel near β biomedical Ti-3Zr-2Sn-3Mo-25Nb alloy, and then NH2- active group was introduced to the films by activation treatment. The phase composition, surface micro-topography and elemental characteristics of the micro-arc oxidation films were investigated with XRD, SEM, EDS and XPS, and the osteoinduction of the micro-arc oxidation films was tested using the simulated body fluid immersion, the in-vitro osteoblast cultivation test and animal experiment. The results show that the oxide layer is a kind of porous ceramic intermixture and contains Ca and P. The films in the simulated body fluid can induce apatite formation, resulting in excellent bioactivity. The cell test discovers that osteoblasts can grow well on the surface of micro-arc oxidation films. And the Ti-3Zr-2Sn-3Mo-25Nb biomedical alloy coated with active porous calcium-phosphate films shows better osteoinduction in vivo.
基金Projects(CKJB201205,QKJB201202,YJK201307)supported by the Nanjing Institute of Technology,China
文摘The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.
基金Projects (50771009, 50731001 and 51071013) supported by the National Natural Science Foundations of China Project (2010CB631200) supported by the National Basic Research Program of China
文摘3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.
基金Project(GC13A113)supported by the Technology Research and Development Program of Heilongjiang Provincial Science and Technology DepartmentProject(12511469)supported by Heilongjiang Provincial Science and Technology Department
文摘Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.
基金Project(50971127)supported by the National Natural Science Foundation of China
文摘A Ti(Al,Si)3 diffusion coating was prepared on γ-TiAl alloy by cold sprayed Al?20Si alloy coating, followed by a heat-treatment. The isothermal and cyclic oxidation tests were conducted at 900 °C for 1000 h and 120 cycles to check the oxidation resistance of the coating. The microstructure and phase transformation of the coating before and after the oxidation were studied by SEM, XRD and EPMA. The results indicate that the diffusion coating shows good oxidation resistance. The mass gain of the diffusion coating is only a quarter of that of bare alloy. After oxidation, the diffusion coating is degraded into three layers: an inner TiAl2 layer, a two-phase intermediate layer composed of a Ti(Al,Si)3 matrix and Si-rich precipitates, and a porous layer because of the inter-diffusion between the coating and substrate.
基金Project (gf200901002) support by the National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology of Nanchang Hangkong University,China
文摘A composite ceramic coating containing Y2O3-ZrO2-MgO（YSZ-MgO） was prepared on AZ91D magnesium alloy,which was immersed in Y（NO3）3 aqueous solution as pretreatment,by micro-arc oxidation（MAO） process.The morphology,elemental and phase compositions,corrosion behavior and thermal stability of the coatings were studied by SEM,EDX,XRD,electrochemical corrosion test,high temperature oxidation and thermal shock test.The results show that the coating mainly consists of ZrO2,Y2O3,MgO,Mg2SiO4,and MgF2.Among these compounds,Y2O3 accounts for 26.7% of（Y2O3 ＋ ZrO2）.The thickness of YSZ-MgO coating is smaller than that of ZrO2-MgO coating,but its compactness and surface roughness are better than those of ZrO2-MgO coating.YSZ-MgO coating has a good corrosion resistance,and its corrosion rate in 5% NaCl aqueous solution is lower than that of ZrO2-MgO and only about 8.5% of that of AZ91D magnesium alloy.After oxidation at 410 °C,the mass gain of AZ91D magnesium alloy presents a linear increase with the oxidation time.The YSZ-MgO coating and ZrO2-MgO coating can remarkably decrease the oxidation mass gain.The oxidation mass gain of YSZ-MgO coating is lower than that of ZrO2-MgO coating,especially during a long oxidation period.The thermal shock resistance of YSZ-MgO coating is superior to ZrO2-MgO coating.
