Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylost...Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylostella.In the present study,we aimed to confirm the resistance risk,cross-resistance,and mechanisms of resistance to thiotraniliprole in P.xylostella.After 40 consecutive generations of thiotraniliprole selection,we obtained a thiotraniliprole-resistance P.xylostella strain with a 5141.58-fold resistance ratio(RR)to thiotraniliprole.The overall realized heritability(h^(2))value of resistance was estimated as 0.9 using threshold trait analysis,indicating that the risk of developing resistance to thiotraniliprole is high in P.xylostella.The thiotraniliprole-resistant(TR)strain showed noticeable cross-resistance to chlorantraniliprole(RR=44670.05),cyantraniliprole(RR=7038.58),and tetrachlorantraniliprole(RR=1506.01),but no cross-resistance to tolfenpyrad,indoxacarb,diafenthiuron,or abamectin compared with the susceptible(S)strain.The enzyme assay data showed that the activities of glutathione-S transferase(GST),carboxylesterase(CarE),and the content of cytochrome P450 monooxygenase(P450s)were significantly higher in the TR strain than in the S strain.Sequencing of the full-length PxRyR cDNA revealed the gene site I4790K in the TR strain with a 100%frequency.This mutation in PxRyR likely underlies the high-level cross-resistance between thiotraniliprole and three other diamide insecticides.These findings provide valuable information for optimizing resistance management strategies to delay thiotraniliprole resistance development and ensure sustainable control of P.xylostella.展开更多
To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxida...To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxidation stage,CeO_(2) accelerated the formation of a multiphase glass layer on the coating surface.The maximum oxidation rates of CeO_(2)-HfB2-SiC coatings with 1%,3%,and 5%CeO_(2) were 24.1%,20.3%,and 53.2%higher than that of the unmodified HfB2-SiC coating,respectively.In the stable oxidation stage,the maximum oxidation rates of coatings with 1%and 3%CeO_(2) decreased by 31.4%and 21.9%,respectively,demonstrating adequate inert protection.CeO_(2) is a“coagulant”and“stabilizer”in the composite glass layer.However,increasing the CeO_(2) content accelerates the reaction between the SiO_(2) glass phase and SiC,leading to a higher SiO_(2) consumption and reduced self-healing ability of the glass layer.The 1%CeO_(2)-60%HfB2-39%SiC coating showed improved glass layer viscosity and stability,moderate SiO_(2) consumption,and better self-healing ability,significantly boosting the oxidation protection of the coating.展开更多
Soybean frogeye leaf spot(FLS)disease is a worldwide disease caused by Cercospora sojina Hara.It is one of the major diseases suffered by soybean during the growth cycle,which seriously damages the yield and seed qual...Soybean frogeye leaf spot(FLS)disease is a worldwide disease caused by Cercospora sojina Hara.It is one of the major diseases suffered by soybean during the growth cycle,which seriously damages the yield and seed quality of soybean.The current resistant varieties are difficult to meet the production demand.The breeders have identified 50 different physiological small species and discussed the physiological and biochemical characteristics of soybean resistance to FLS.In soybean disease resistance breeding,resistance resources are screened for the main physiological races in different countries,resistance materials are created,more than 100 genome regions associated with resistance are located,and 12 resistance-related genes are identified.In order to promote the research of soybean disease resistance breeding,this paper expounded and analyzed the pathogenesis characteristics of soybean FLS,the division of races,the physiological and biochemical mechanism of soybean resistance to FLS disease,quantitative trait locus(QTL),quantitative trait nucleotides(QTN),genes of resistance sites,the screening of resistant germplasm resources,and the breeding of new varieties,so as to gain an in-depth understanding of the pathogenesis principle of soybean FLS disease.In order to provide a theoretical basis and technical support for the breeding of soybean FLS disease,the resistance mechanism of soybean FLS disease was analyzed from the molecular level.展开更多
To enhance the resistance of honeycomb sandwich panel against local impact,this study delved into the matching relationship between face sheets and core.An integrated approach,combining experiment,simulation,and theor...To enhance the resistance of honeycomb sandwich panel against local impact,this study delved into the matching relationship between face sheets and core.An integrated approach,combining experiment,simulation,and theoretical methods,was used.Local loading experiments were conducted to validate the accuracy of the finite element model.Furthermore,a control equation was formulated to correlate structural parameters with response modes,and a matching coefficientλ(representing the ratio of core thickness to face sheet thickness)was introduced to establish a link between these parameters and impact characteristics.A demand-driven reverse design methodology for structural parameters was developed,with numerical simulations employed to assess its effectiveness.The results indicate that the proposed theory can accurately predict response modes and key indicators.An increase in theλbolsters the structural indentation resistance while concurrently heightens the likelihood of penetration.Conversely,a decrease in theλimproves the resistance to penetration,albeit potentially leading to significant deformations in the rear face sheet.Numerical simulations demonstrate that the reverse design methodology significantly enhances the structural penetration resistance.Comparative analyses indicate that appropriate matching reduces indentation depth by 27.4% and indentation radius by 41.8%of the proposed structure.展开更多
Verticillium wilt,caused by the infamous pathogen Verticillium dahliae,presents a primary constraint on cotton cul-tivation worldwide.The complexity of disease resistance in cotton and the largely unexplored interacti...Verticillium wilt,caused by the infamous pathogen Verticillium dahliae,presents a primary constraint on cotton cul-tivation worldwide.The complexity of disease resistance in cotton and the largely unexplored interaction dynamics between the cotton plant host and V.dahliae pathogen pose a crucial predicament for effectively managing cotton Verticillium wilt.Nevertheless,the most cost-effective approach to controlling this disease involves breeding and cul-tivating resistant cotton varieties,demanding a meticulous analysis of the mechanisms underlying cotton’s resistance to Verticillium wilt and the identification of pivotal genes.These aspects constitute focal points in disease-resistance breeding programs.In this review,we comprehensively discuss genetic inheritance associated with Verticillium wilt resistance in cotton,the advancements in molecular markers for disease resistance,the functional investiga-tion of resistance genes in cotton,the analysis of pathogenicity genes in V.dahliae,as well as the intricate interplay between cotton and this fungus.Moreover,we delve into the future prospects of cutting-edge research on cotton Verticillium wilt,aiming to proffer valuable insights for the effective management of this devastating fungus.展开更多
Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morpho...Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morphology simulation with an enhanced agglomerate model to establish a mathematical framework elucidating pore evolution,Pt utilization,and oxygen transport in catalyst layers.Results demonstrate dominant local mass transport resistance governed by three factors:(1)active site density dictating oxygen flux;(2)ionomer film thickness defining shortest transport path;(3)ionomer-to-Pt surface area ratio modulating practical pathway length.At low ionomer-to-carbon(I/C)ratios,limited active sites elevate resistance(Factor 1 dominant).Higher I/C ratios improve the ionomer coverage but eventually thicken ionomer films,degrading transport(Factors 2–3 dominant).The results indicate that larger carbon particles result in a net increase in local transport resistance by reducing external surface area and increasing ionomer thickness.As the proportion of Pt situated in nanopores or the Pt mass fraction increases,elevated Pt density inside the nanopores exacerbates pore blockage.This leads to the increased transport resistance by reducing active sites,and increasing ionomer thickness and surface area.Lower Pt loading linearly intensifies oxygen flux resistance.The model underscores the necessity to optimize support morphology,Pt distribution,and ionomer content to prevent pore blockage while balancing catalytic activity and transport efficiency.These insights provide a systematic approach for designing high-performance mesoporous carbon catalysts.展开更多
Drug resistance remains a major challenge in breast cancer chemotherapy,yet the metabolic alterations underlying this phenomenon are not fully understood.There is much evidence indicating the cellular heterogeneity am...Drug resistance remains a major challenge in breast cancer chemotherapy,yet the metabolic alterations underlying this phenomenon are not fully understood.There is much evidence indicating the cellular heterogeneity among cancer cells,which exhibit varying degrees of metabolic reprogramming and thus may result in differential contributions to drug resistance.A home-built single-cell quantitative mass spectrometry(MS)platform,which integrates micromanipulation and electro-osmotic sampling,was developed to quantitatively profile the tricarboxylic acid(TCA)cycle metabolites at the single-cell level.Using this platform,the metabolic profiles of drug-sensitive MCF-7 breast cancer cells and their drug-resistant derivative MCF-7/ADR cells were compared.This results revealed a selective upregulation of downstream TCA cycle metabolites includingα-ketoglutarate,succinate,fumarate,and malate in drug-resistant cancer cells,while early TCA metabolites remained largely unchanged.Furthermore,notable variations in the abundance of the metabolites were observed in individual cells.The comparative analysis also revealed that not all MCF-7/ADR cells exhibit the same degree of metabolic deviation from the parental line in the metabolites during resistance acquisition.The observed metabolic profiles indicate enhanced glutaminolysis,altered mitochondrial electron transport chain activity,and increased metabolic flexibility in drug-resistant cancer cells that support their survival under chemotherapeutic stress.The findings further suggest the potential for incorporating cellular metabolic heterogeneity into future drug resistance studies.展开更多
In recent years,the prevalence of rice sheath blight caused by Rhizoctonia solani has significantly increased in Heilongjiang Province.Chemical control has become the primary control method.To cope with this,a novel m...In recent years,the prevalence of rice sheath blight caused by Rhizoctonia solani has significantly increased in Heilongjiang Province.Chemical control has become the primary control method.To cope with this,a novel mycelium growth rate method was employed to assess the toxicity of 13 fungicides,including a combination of 45%prochloraz and 125 g·mL^(-1)epoxiconazole,against R.solani.Additionally,the resistance of 99 R.solani strains to thifluzamide across various regions was also evaluated.The findings indicated that 75%trifloxystrobin-tebuconazole exhibited the most effective inhibitory effect,with an effective inhibitory medium concentration(EC50)value of 0.0101μg·mL^(-1).The EC50 values for 20%prothioconazole,125 g·mL^(-1)epoxiconazole,24%thifluzamide,and 50%hexaconazole were all less than 10μg·mL^(-1),indicating a better inhibitory effect on R.solani.The strongest synergistic effect was noted in the mixture of prochloraz and epoxiconazole at a 1:2 ratio,resulting in an EC50 value of 2.9917μg·mL^(-1),and a co-toxicity coefficient of 213.38.Among the 34 strains from Harbin City,the average EC50 value was 196.9341μg·mL^(-1)indicating the highest susceptiblility to thifluzamide.Conversely,15 strains from Shuangyashan City exhibited an average EC50 value of 364.7323μg·mL^(-1),reflecting the lowest sensitivity to thifluzamide.The sensitivity baseline EC50 value for R.solani was 253.8854μg·mL^(-1),with an overall resistance level between 0.1567 and 3.3292,indicating that the resistance level of R.solani in Heilongjiang Province remained low.Therefore,R.solani was still sensitive to thifluzamide in most areas of Heilongjiang Province,but there was a certain risk of resistance in Qitaihe City,which needed to be continuously monitored.At the same time,this study might provide a theoretical foundation for enhancing the prevention and management of the rice sheath blight.展开更多
Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by ad...Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.展开更多
The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the...The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the grain boundaries were pinned by high-density nanosized Al_(3)(Yb,Zr)precipitates during extrusion deformation,consequently,the average grain size was significantly reduced from 232.7μm to 3.2μm.This grain refinement contributed substantially to the improvement in both strength and elongation.The ultimate tensile strength,yield strength,and elongation of the Yb/Zr modified alloy increased to 705.3 MPa,677.6 MPa,and 8.7%,respectively,representing enhancements of 16.2%,19.3%,and 112.2%compared to the unmodified alloy.Moreover,the distribution of MgZn_(2)phases along grain boundaries became more discontinuous in the Yb/Zr modified alloy,which effectively retarded the propagation of intergranular corrosion and improved the corrosion resistance.展开更多
This study proposes a general imperfect thermal contact model to predict the thermal contact resistance at the interface among multi-layered composite structures.Based on the Green-Lindsay(GL)thermoelastic theory,semi...This study proposes a general imperfect thermal contact model to predict the thermal contact resistance at the interface among multi-layered composite structures.Based on the Green-Lindsay(GL)thermoelastic theory,semi analytical solutions of temperature increment and displacement of multi-layered composite structures are obtained by using the Laplace transform method,upon which the effects of thermal resistance coefficient,partition coefficient,thermal conductivity ratio and heat capacity ratio on the responses are studied.The results show that the generalized imperfect thermal contact model can realistically describe the imperfect thermal contact problem.Accordingly,it may degenerate into other thermal contact models by adjusting the thermal resistance coefficient and partition coefficient.展开更多
Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the...Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the effects of textile structure,layering,and ply orientation on the stab resistance of multi-layer textiles.Three 3D warp interlock(3DWI)structures({f1},{f2},{f3})and a 2D woven fabric({f4}),all made of high-performance p-aramid yarns,were engineered and manufactured.Multi-layer specimens were prepared and subjected to drop-weight stabbing tests following HOSBD standards.Stabbing performance metrics,including Depth of Trauma(DoT),Depth of Penetration(DoP),and trauma deformation(Ymax,Xmax),were investigated and analyzed.Statistical analyses(Two-and One-Way ANOVA)indicated that fabric type and layer number significantly impacted DoP(P<0.05),while ply orientation significantly affected DoP(P<0.05)but not DoT(P>0.05).Further detailed analysis revealed that 2D woven fabrics exhibited greater trauma deformation than 3D WIF structures.Increasing the number of layers reduced both DoP and DoT across all fabric structures,with f3 demonstrating the best performance in multi-layer configurations.Aligned ply orientations also enhanced stab resistance,underscoring the importance of alignment in dissipating impact energy.展开更多
Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines pla...Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines plasma-enhanced non-equilibrium magnetron sputtering physical vapor deposition(PEUMS-PVD)and anodization to construct a self-healing three-dimensional Ti/Al-doped TiO_(2)nanotubes/Ti_(3)AlC_(2)coating on the surface of Cu substrates.This novel strategy enhances the corrosion resistance of copper substrates in marine environments,with corrosion current densities of up to 4.5643×10^(−8)A/cm^(2).Among them,the doping of nano-aluminum particles makes the coating self-healing.The mechanistic analysis of the corrosion behaviors during early immersion experiments was conducted using electrochemical noise,and revealed that during the initial stages of coating immersion,uniform corrosion predominates,with a minor occurrence of localized corrosion.展开更多
Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and...Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.展开更多
This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-...This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.展开更多
Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter t...Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.展开更多
In order to understand how chitosan affects disease resistance and quality of navel orange fruit(Citrussinensis L.osbeck)cv.Newhall after harvest,navel orange fruits were treated with 2 g chitosan/100 g solution for 1...In order to understand how chitosan affects disease resistance and quality of navel orange fruit(Citrussinensis L.osbeck)cv.Newhall after harvest,navel orange fruits were treated with 2 g chitosan/100 g solution for 1 min,and some fruits were taken out,dried naturally and inoculated with Penicillium italicum.Then,the fruits were stored at 20℃and 85%to 95%RH.Results indicated that the disease incidence and the lesion diameter in the chitosan-treated fruit are 72.72%and 90.19%,lower than those in control fruit on the 18^th day of incubation.The chitosan treatment maintains the soluble protein content,total phenolic and flavonoid level of navel orange fruit,which maybe involve in the maintenance of disease resistance of navel orange fruit.Treating navel orange fruit with 2 g chitosan/100 g solution effectively reduces the decrease in the content ofascorbic acid(AsA),water,titratable acidity(TA)and total soluble solids(TSS).These results suggested that the treatment with chitosan coating enhances the disease resistance and exhibits a potential for storage life extension of the navel orange fruit stored at ambient temperature.展开更多
Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechan...Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.展开更多
The tensile creep resistance of Mg-5.5%Zn-(0.7%, 1.5%, 3.5%, 7.5%)Y(mass fraction, %) gravity-casting alloys was investigated systematically. The corresponding physical models were established for analyzing the micros...The tensile creep resistance of Mg-5.5%Zn-(0.7%, 1.5%, 3.5%, 7.5%)Y(mass fraction, %) gravity-casting alloys was investigated systematically. The corresponding physical models were established for analyzing the microstructure evolution and creep mechanism. The results show that four second phases are found in Mg-5.5%Zn-(0.7%, 1.5%, 3.5%, 7.5%)Y alloys, including Mg3 Zn Y, Mg3Zn6 Y, Mg3Zn3Y2 and Mg7Zn3, where the rare earth rich phase(Mg3Zn Y, Mg3Zn6 Y, Mg3Zn3Y2) with high melting point can more effectively improve the creep resistance properties of alloys than Mg7Zn3. With the increasing of Y content, the creep resistance of alloys is improved correspondingly. The alloys with(1.5%, 3.5%)Y addition exhibit high creep resistance at temperatures from 175 °C to 200 °C and load from 55 MPa to 70 MPa. The 7.5%Y added alloy presents excellent creep resistance even at 275 °C and 55 MPa. The second phase which shows discontinuous distribution at the grain boundary of(0.7%, 1.5%, 3.5%)Y added alloys has preferred orientation and clogs in triple junctions of grain boundary. Simultaneously, the arrangement of second phase particles along tensile direction and the formation of denuded zones are observed during the creep process. Moreover, the crack initiates in these areas and propagates along grain boundary. Compared with discontinuous second phase, the continuous skeleton-like second phase of 7.5%Y added alloy at grain boundary has a better effect on improving the creep resistance properties of alloys.展开更多
基金Supported by the Zhejiang Provincial Public Welfare Technology Application Research Program(No:LGN21C140001).
文摘Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylostella.In the present study,we aimed to confirm the resistance risk,cross-resistance,and mechanisms of resistance to thiotraniliprole in P.xylostella.After 40 consecutive generations of thiotraniliprole selection,we obtained a thiotraniliprole-resistance P.xylostella strain with a 5141.58-fold resistance ratio(RR)to thiotraniliprole.The overall realized heritability(h^(2))value of resistance was estimated as 0.9 using threshold trait analysis,indicating that the risk of developing resistance to thiotraniliprole is high in P.xylostella.The thiotraniliprole-resistant(TR)strain showed noticeable cross-resistance to chlorantraniliprole(RR=44670.05),cyantraniliprole(RR=7038.58),and tetrachlorantraniliprole(RR=1506.01),but no cross-resistance to tolfenpyrad,indoxacarb,diafenthiuron,or abamectin compared with the susceptible(S)strain.The enzyme assay data showed that the activities of glutathione-S transferase(GST),carboxylesterase(CarE),and the content of cytochrome P450 monooxygenase(P450s)were significantly higher in the TR strain than in the S strain.Sequencing of the full-length PxRyR cDNA revealed the gene site I4790K in the TR strain with a 100%frequency.This mutation in PxRyR likely underlies the high-level cross-resistance between thiotraniliprole and three other diamide insecticides.These findings provide valuable information for optimizing resistance management strategies to delay thiotraniliprole resistance development and ensure sustainable control of P.xylostella.
文摘To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxidation stage,CeO_(2) accelerated the formation of a multiphase glass layer on the coating surface.The maximum oxidation rates of CeO_(2)-HfB2-SiC coatings with 1%,3%,and 5%CeO_(2) were 24.1%,20.3%,and 53.2%higher than that of the unmodified HfB2-SiC coating,respectively.In the stable oxidation stage,the maximum oxidation rates of coatings with 1%and 3%CeO_(2) decreased by 31.4%and 21.9%,respectively,demonstrating adequate inert protection.CeO_(2) is a“coagulant”and“stabilizer”in the composite glass layer.However,increasing the CeO_(2) content accelerates the reaction between the SiO_(2) glass phase and SiC,leading to a higher SiO_(2) consumption and reduced self-healing ability of the glass layer.The 1%CeO_(2)-60%HfB2-39%SiC coating showed improved glass layer viscosity and stability,moderate SiO_(2) consumption,and better self-healing ability,significantly boosting the oxidation protection of the coating.
基金Supported by the 14th Five-Year National Key Research and Development Program(2021YFD1201103–01–05)the National Natural Science Foundation of China(32301819)the Cooperation Project of Research and Development Center between Wudalianchi Government and Northeast Agricultural University.
文摘Soybean frogeye leaf spot(FLS)disease is a worldwide disease caused by Cercospora sojina Hara.It is one of the major diseases suffered by soybean during the growth cycle,which seriously damages the yield and seed quality of soybean.The current resistant varieties are difficult to meet the production demand.The breeders have identified 50 different physiological small species and discussed the physiological and biochemical characteristics of soybean resistance to FLS.In soybean disease resistance breeding,resistance resources are screened for the main physiological races in different countries,resistance materials are created,more than 100 genome regions associated with resistance are located,and 12 resistance-related genes are identified.In order to promote the research of soybean disease resistance breeding,this paper expounded and analyzed the pathogenesis characteristics of soybean FLS,the division of races,the physiological and biochemical mechanism of soybean resistance to FLS disease,quantitative trait locus(QTL),quantitative trait nucleotides(QTN),genes of resistance sites,the screening of resistant germplasm resources,and the breeding of new varieties,so as to gain an in-depth understanding of the pathogenesis principle of soybean FLS disease.In order to provide a theoretical basis and technical support for the breeding of soybean FLS disease,the resistance mechanism of soybean FLS disease was analyzed from the molecular level.
基金Project(2022A02480004)supported by the Major Project of China Railway Design CorporationProject(2023RC1011)supported by the Science and Technology Innovation Program of Hunan Province,China+2 种基金Project(2024JJ6515)supported by the Hunan Provincial Natural Science Foundation,ChinaProject(kq2402220)supported by the Natural Science Foundation of Changsha City,ChinaProject(52402438)supported by the National Natural Science Foundation of China。
文摘To enhance the resistance of honeycomb sandwich panel against local impact,this study delved into the matching relationship between face sheets and core.An integrated approach,combining experiment,simulation,and theoretical methods,was used.Local loading experiments were conducted to validate the accuracy of the finite element model.Furthermore,a control equation was formulated to correlate structural parameters with response modes,and a matching coefficientλ(representing the ratio of core thickness to face sheet thickness)was introduced to establish a link between these parameters and impact characteristics.A demand-driven reverse design methodology for structural parameters was developed,with numerical simulations employed to assess its effectiveness.The results indicate that the proposed theory can accurately predict response modes and key indicators.An increase in theλbolsters the structural indentation resistance while concurrently heightens the likelihood of penetration.Conversely,a decrease in theλimproves the resistance to penetration,albeit potentially leading to significant deformations in the rear face sheet.Numerical simulations demonstrate that the reverse design methodology significantly enhances the structural penetration resistance.Comparative analyses indicate that appropriate matching reduces indentation depth by 27.4% and indentation radius by 41.8%of the proposed structure.
基金supported by National Natural Science Foundation of China(32201752)Xinjiang Tianchi Talents Program (TCYC2023TP02)Key Project of the Natural Science Foundation of Xinjiang Production and Construction Corps (2024DA001)
文摘Verticillium wilt,caused by the infamous pathogen Verticillium dahliae,presents a primary constraint on cotton cul-tivation worldwide.The complexity of disease resistance in cotton and the largely unexplored interaction dynamics between the cotton plant host and V.dahliae pathogen pose a crucial predicament for effectively managing cotton Verticillium wilt.Nevertheless,the most cost-effective approach to controlling this disease involves breeding and cul-tivating resistant cotton varieties,demanding a meticulous analysis of the mechanisms underlying cotton’s resistance to Verticillium wilt and the identification of pivotal genes.These aspects constitute focal points in disease-resistance breeding programs.In this review,we comprehensively discuss genetic inheritance associated with Verticillium wilt resistance in cotton,the advancements in molecular markers for disease resistance,the functional investiga-tion of resistance genes in cotton,the analysis of pathogenicity genes in V.dahliae,as well as the intricate interplay between cotton and this fungus.Moreover,we delve into the future prospects of cutting-edge research on cotton Verticillium wilt,aiming to proffer valuable insights for the effective management of this devastating fungus.
基金supported by the Program of Ministry of Science and Technology of China(No.2023YFB2504200)support of Shanghai Rising-Star Program(Grant No.24QB2703200)the Major Science and Technology Projects of Yunnan Province(No.202302AH360001).
文摘Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morphology simulation with an enhanced agglomerate model to establish a mathematical framework elucidating pore evolution,Pt utilization,and oxygen transport in catalyst layers.Results demonstrate dominant local mass transport resistance governed by three factors:(1)active site density dictating oxygen flux;(2)ionomer film thickness defining shortest transport path;(3)ionomer-to-Pt surface area ratio modulating practical pathway length.At low ionomer-to-carbon(I/C)ratios,limited active sites elevate resistance(Factor 1 dominant).Higher I/C ratios improve the ionomer coverage but eventually thicken ionomer films,degrading transport(Factors 2–3 dominant).The results indicate that larger carbon particles result in a net increase in local transport resistance by reducing external surface area and increasing ionomer thickness.As the proportion of Pt situated in nanopores or the Pt mass fraction increases,elevated Pt density inside the nanopores exacerbates pore blockage.This leads to the increased transport resistance by reducing active sites,and increasing ionomer thickness and surface area.Lower Pt loading linearly intensifies oxygen flux resistance.The model underscores the necessity to optimize support morphology,Pt distribution,and ionomer content to prevent pore blockage while balancing catalytic activity and transport efficiency.These insights provide a systematic approach for designing high-performance mesoporous carbon catalysts.
基金supported by National Natural Science Foundation of China(22374080,22174068,21722504)Primary Research&Development Plan of Jiangsu Province(BK20221303,BE2022796)+1 种基金Open Foundation of State Key Laboratory of Reproductive Medicine(SKLRM-2022BP1,JX116GSP20240507)Science and Technology Development Fund of NJMU(NJMUQY2022003)。
文摘Drug resistance remains a major challenge in breast cancer chemotherapy,yet the metabolic alterations underlying this phenomenon are not fully understood.There is much evidence indicating the cellular heterogeneity among cancer cells,which exhibit varying degrees of metabolic reprogramming and thus may result in differential contributions to drug resistance.A home-built single-cell quantitative mass spectrometry(MS)platform,which integrates micromanipulation and electro-osmotic sampling,was developed to quantitatively profile the tricarboxylic acid(TCA)cycle metabolites at the single-cell level.Using this platform,the metabolic profiles of drug-sensitive MCF-7 breast cancer cells and their drug-resistant derivative MCF-7/ADR cells were compared.This results revealed a selective upregulation of downstream TCA cycle metabolites includingα-ketoglutarate,succinate,fumarate,and malate in drug-resistant cancer cells,while early TCA metabolites remained largely unchanged.Furthermore,notable variations in the abundance of the metabolites were observed in individual cells.The comparative analysis also revealed that not all MCF-7/ADR cells exhibit the same degree of metabolic deviation from the parental line in the metabolites during resistance acquisition.The observed metabolic profiles indicate enhanced glutaminolysis,altered mitochondrial electron transport chain activity,and increased metabolic flexibility in drug-resistant cancer cells that support their survival under chemotherapeutic stress.The findings further suggest the potential for incorporating cellular metabolic heterogeneity into future drug resistance studies.
基金Supported by the Green Plant Protection Project(213010801)the Heilongjiang Province Key Research and Development Plan Project(20232X02 B0502)the Natural Science Foundation of Heilongjiang Province(LH2022C022)。
文摘In recent years,the prevalence of rice sheath blight caused by Rhizoctonia solani has significantly increased in Heilongjiang Province.Chemical control has become the primary control method.To cope with this,a novel mycelium growth rate method was employed to assess the toxicity of 13 fungicides,including a combination of 45%prochloraz and 125 g·mL^(-1)epoxiconazole,against R.solani.Additionally,the resistance of 99 R.solani strains to thifluzamide across various regions was also evaluated.The findings indicated that 75%trifloxystrobin-tebuconazole exhibited the most effective inhibitory effect,with an effective inhibitory medium concentration(EC50)value of 0.0101μg·mL^(-1).The EC50 values for 20%prothioconazole,125 g·mL^(-1)epoxiconazole,24%thifluzamide,and 50%hexaconazole were all less than 10μg·mL^(-1),indicating a better inhibitory effect on R.solani.The strongest synergistic effect was noted in the mixture of prochloraz and epoxiconazole at a 1:2 ratio,resulting in an EC50 value of 2.9917μg·mL^(-1),and a co-toxicity coefficient of 213.38.Among the 34 strains from Harbin City,the average EC50 value was 196.9341μg·mL^(-1)indicating the highest susceptiblility to thifluzamide.Conversely,15 strains from Shuangyashan City exhibited an average EC50 value of 364.7323μg·mL^(-1),reflecting the lowest sensitivity to thifluzamide.The sensitivity baseline EC50 value for R.solani was 253.8854μg·mL^(-1),with an overall resistance level between 0.1567 and 3.3292,indicating that the resistance level of R.solani in Heilongjiang Province remained low.Therefore,R.solani was still sensitive to thifluzamide in most areas of Heilongjiang Province,but there was a certain risk of resistance in Qitaihe City,which needed to be continuously monitored.At the same time,this study might provide a theoretical foundation for enhancing the prevention and management of the rice sheath blight.
基金the Major Science and Technology Demonstration Projects in Jiangsu Province(Grant No.BE2022608).
文摘Inspired by the thermal stability mechanism of thermophilic protein,which presents ionic bonds that have better stability at higher temperatures,this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica(C-SiO2),PAA,and CaCl_(2) to achieve higher viscosity over 25℃.The rheological behavior of C-SiO_(2)-based shear thickening fluid(CS-STF)was investigated at a temperature range of 25–55℃.Unlike SiO_(2)-based STF,which exhibits single-step thickening and a negative correlation between viscosity and temperature.As the C-SiO_(2) content was 41%(w/w)and the mass ratio of PAA:CaCl_(2):C-SiO_(2) was 3:1:10,the CS-STF displayed a double-thickening behavior,and the peak viscosity reached 1330 Pa·s at 35℃.From the yarn pull-out test,the inter-yarn force was significantly increased with the increasing CS-STF content.Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively.In the blunt impact test,the U-CS fabrics with high CS-STF content(121.45 wt%)experienced penetration failure under high impact energy(18 J)due to stress concentration caused by the shear thickening behavior.The knife stabbing test demonstrated that U-CS fabrics with appropriate content(88.38 wt%)have the best stabbing resistance in various impact energies.Overall,this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range,the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.
基金Project(51501228)supported by the National Natural Science Foundation of ChinaProject(202109)supported by the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China。
文摘The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the grain boundaries were pinned by high-density nanosized Al_(3)(Yb,Zr)precipitates during extrusion deformation,consequently,the average grain size was significantly reduced from 232.7μm to 3.2μm.This grain refinement contributed substantially to the improvement in both strength and elongation.The ultimate tensile strength,yield strength,and elongation of the Yb/Zr modified alloy increased to 705.3 MPa,677.6 MPa,and 8.7%,respectively,representing enhancements of 16.2%,19.3%,and 112.2%compared to the unmodified alloy.Moreover,the distribution of MgZn_(2)phases along grain boundaries became more discontinuous in the Yb/Zr modified alloy,which effectively retarded the propagation of intergranular corrosion and improved the corrosion resistance.
基金Projects(42477162,52108347,52178371,52168046,52178321,52308383)supported by the National Natural Science Foundation of ChinaProjects(2023C03143,2022C01099,2024C01219,2022C03151)supported by the Zhejiang Key Research and Development Plan,China+6 种基金Project(LQ22E080010)supported by the Exploring Youth Project of Zhejiang Natural Science Foundation,ChinaProject(LR21E080005)supported by the Outstanding Youth Project of Natural Science Foundation of Zhejiang Province,ChinaProject(2022M712964)supported by the Postdoctoral Science Foundation of ChinaProject(2023AFB008)supported by the Natural Science Foundation of Hubei Province for Youth,ChinaProject(202203)supported by Engineering Research Centre of Rock-Soil Drilling&Excavation and Protection,Ministry of Education,ChinaProject(202305-2)supported by the Science and Technology Project of Zhejiang Provincial Communication Department,ChinaProject(2021K256)supported by the Construction Research Founds of Department of Housing and Urban-Rural Development of Zhejiang Province,China。
文摘This study proposes a general imperfect thermal contact model to predict the thermal contact resistance at the interface among multi-layered composite structures.Based on the Green-Lindsay(GL)thermoelastic theory,semi analytical solutions of temperature increment and displacement of multi-layered composite structures are obtained by using the Laplace transform method,upon which the effects of thermal resistance coefficient,partition coefficient,thermal conductivity ratio and heat capacity ratio on the responses are studied.The results show that the generalized imperfect thermal contact model can realistically describe the imperfect thermal contact problem.Accordingly,it may degenerate into other thermal contact models by adjusting the thermal resistance coefficient and partition coefficient.
文摘Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
文摘Stab-resistant textiles play a critical role in personal protection,necessitating a deeper understanding of how structural and layering factors influence their performance.The current study experimentally examines the effects of textile structure,layering,and ply orientation on the stab resistance of multi-layer textiles.Three 3D warp interlock(3DWI)structures({f1},{f2},{f3})and a 2D woven fabric({f4}),all made of high-performance p-aramid yarns,were engineered and manufactured.Multi-layer specimens were prepared and subjected to drop-weight stabbing tests following HOSBD standards.Stabbing performance metrics,including Depth of Trauma(DoT),Depth of Penetration(DoP),and trauma deformation(Ymax,Xmax),were investigated and analyzed.Statistical analyses(Two-and One-Way ANOVA)indicated that fabric type and layer number significantly impacted DoP(P<0.05),while ply orientation significantly affected DoP(P<0.05)but not DoT(P>0.05).Further detailed analysis revealed that 2D woven fabrics exhibited greater trauma deformation than 3D WIF structures.Increasing the number of layers reduced both DoP and DoT across all fabric structures,with f3 demonstrating the best performance in multi-layer configurations.Aligned ply orientations also enhanced stab resistance,underscoring the importance of alignment in dissipating impact energy.
基金Projects(42106051,42006046,U2106206) supported by the National Natural Science Foundation of ChinaProject(22373501D) supported by Hebei Provincial Key R&D Program,China。
文摘Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines plasma-enhanced non-equilibrium magnetron sputtering physical vapor deposition(PEUMS-PVD)and anodization to construct a self-healing three-dimensional Ti/Al-doped TiO_(2)nanotubes/Ti_(3)AlC_(2)coating on the surface of Cu substrates.This novel strategy enhances the corrosion resistance of copper substrates in marine environments,with corrosion current densities of up to 4.5643×10^(−8)A/cm^(2).Among them,the doping of nano-aluminum particles makes the coating self-healing.The mechanistic analysis of the corrosion behaviors during early immersion experiments was conducted using electrochemical noise,and revealed that during the initial stages of coating immersion,uniform corrosion predominates,with a minor occurrence of localized corrosion.
文摘Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.
文摘This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.
基金Financial assistance from Armament Research Board, New Delhi, India
文摘Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.
文摘In order to understand how chitosan affects disease resistance and quality of navel orange fruit(Citrussinensis L.osbeck)cv.Newhall after harvest,navel orange fruits were treated with 2 g chitosan/100 g solution for 1 min,and some fruits were taken out,dried naturally and inoculated with Penicillium italicum.Then,the fruits were stored at 20℃and 85%to 95%RH.Results indicated that the disease incidence and the lesion diameter in the chitosan-treated fruit are 72.72%and 90.19%,lower than those in control fruit on the 18^th day of incubation.The chitosan treatment maintains the soluble protein content,total phenolic and flavonoid level of navel orange fruit,which maybe involve in the maintenance of disease resistance of navel orange fruit.Treating navel orange fruit with 2 g chitosan/100 g solution effectively reduces the decrease in the content ofascorbic acid(AsA),water,titratable acidity(TA)and total soluble solids(TSS).These results suggested that the treatment with chitosan coating enhances the disease resistance and exhibits a potential for storage life extension of the navel orange fruit stored at ambient temperature.
基金sponsored by the National Natural Science Foundation of China ( 51571150,11572222)Tianjin Natural Science Foundation ( 14JCYBJC16900)
文摘Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.
基金Project(14JJ1013)supported by Natural Science Foundation of Hunan ProvinceChina
文摘The tensile creep resistance of Mg-5.5%Zn-(0.7%, 1.5%, 3.5%, 7.5%)Y(mass fraction, %) gravity-casting alloys was investigated systematically. The corresponding physical models were established for analyzing the microstructure evolution and creep mechanism. The results show that four second phases are found in Mg-5.5%Zn-(0.7%, 1.5%, 3.5%, 7.5%)Y alloys, including Mg3 Zn Y, Mg3Zn6 Y, Mg3Zn3Y2 and Mg7Zn3, where the rare earth rich phase(Mg3Zn Y, Mg3Zn6 Y, Mg3Zn3Y2) with high melting point can more effectively improve the creep resistance properties of alloys than Mg7Zn3. With the increasing of Y content, the creep resistance of alloys is improved correspondingly. The alloys with(1.5%, 3.5%)Y addition exhibit high creep resistance at temperatures from 175 °C to 200 °C and load from 55 MPa to 70 MPa. The 7.5%Y added alloy presents excellent creep resistance even at 275 °C and 55 MPa. The second phase which shows discontinuous distribution at the grain boundary of(0.7%, 1.5%, 3.5%)Y added alloys has preferred orientation and clogs in triple junctions of grain boundary. Simultaneously, the arrangement of second phase particles along tensile direction and the formation of denuded zones are observed during the creep process. Moreover, the crack initiates in these areas and propagates along grain boundary. Compared with discontinuous second phase, the continuous skeleton-like second phase of 7.5%Y added alloy at grain boundary has a better effect on improving the creep resistance properties of alloys.
