By enhancing surface interaction between metal oxide particles and carbon-based materials,it can effectively improve Faraday capacitance and conductivity,ultimately achieving high energy density with sufficient redox ...By enhancing surface interaction between metal oxide particles and carbon-based materials,it can effectively improve Faraday capacitance and conductivity,ultimately achieving high energy density with sufficient redox reactions in supercapacitors.Through a gentle biomineralization process and subsequent thermal reduction strategy,we successfully prepared the graphene oxide(GO)wrapping mixed-valence manganese oxides(MnO_(x))and S,P self-codoped carbon matrix porous composite(MnO_(x)@SPC@reduced graphene oxide(RGO)).During the biomineralization process of engineered Pseudomonas sp.(Ml)cells,GO nanosheets functioned as the'soil'to adsorb Mn^(2+)ion and uniformly disperse biogenic Mn oxides(BMO).After undergoing annealing,the MnO_(x) nanoparticles were evenly wrapped with graphene,resulting in the creation of the MnO_(x)@SPC@RGO3 composite.This composite possesses strong C—O—Mn bond interfaces,numerous electroactive sites,and a uniform pore structure.By optimizing the synergistic interaction between the highly conductive graphene and the remarkable surface capacitance of MnO_(x),the MnO_(x)@SPC@RGO3 electrode,with its intercalation Faraday reactions mechanism of■transformations,exhibits an outstanding specific capacity(448.3 F·g^(-1)at 0.5 A·g^(-1)),multiplying performance(340.5 F·g^(-1)at10 A·g^(-1)),and cycling stability(93.8%retention after 5000 cycles).Moreover,the asymmetric all-solidstate supercapacitors of MnO_(x)@SPC@RGO3//PC exhibit an exceptional energy density of 64.8 W·h·kg^(-1)and power density of 350 W·kg^(-1),as well as a long lifespan with capacitance retention of 92.5%after10000 cycles.In conclusion,the synthetic route utilizing biomineralization and thermal reduction exhibits significant potential for exploiting high-performance electrode materials in all-solid-state supercapacitor applications.展开更多
Labor education serves as an essential pathway for student development,offering comprehensive educational values in cultivating moral integrity,enhancing intellectual growth,strengthening physical fitness,and nurturin...Labor education serves as an essential pathway for student development,offering comprehensive educational values in cultivating moral integrity,enhancing intellectual growth,strengthening physical fitness,and nurturing aesthetic appreciation.Using traditional poetry,a cultural gene of the Chinese nation,as a medium,students can not only expand their labor knowledge and practical skills but also gain insights into traditional virtues and strengthen cultural confidence.This paper attempts to explore innovative approaches to integrating Chinese poetry education with primary school labor education.Through in-depth analysis of current labor practices in primary schools and the innovative value of these integration pathways,the study provides innovative ideas and methods for primary school labor education.The goal is to help students deepen cultural literacy through hands-on experiences,use culture as nourishment to improve their labor literacy,and achieve the educational objective of holistic development.展开更多
The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructur...The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructural evolution and deformation mechanisms of hat-shaped specimens were revealed by electron backscattered diffraction(EBSD)method.It is found that the nucleation and expansion of adiabatic shear band(ASB)are affected by both geometric and structural factors.The increase of dislocation density,structure fragment and temperature rise in the deformation-affected regions provide basic microstructural conditions.In addition to the dislocation slips,the extension twins detected in shear region also play a critical role in microstructural fragmentation due to twin-boundaries effect.Interestingly,the sandwich structure imposes a crucial influence on ASB,which finally becomes a mature wide ASB in the dynamic deformation.However,due to much larger width,the sandwich structure in the middle of shear region is also possible to serve as favorable nucleation sites for crack initiation.展开更多
Hearing loss is the most common sensorineural disorder worldwide and is associated with more than1000 mutations in more than 90 genes. While mutations in genes such as GJB2(gap-junction protein β 2)and GJB6(gap-junct...Hearing loss is the most common sensorineural disorder worldwide and is associated with more than1000 mutations in more than 90 genes. While mutations in genes such as GJB2(gap-junction protein β 2)and GJB6(gap-junction protein β 6) are highly prevalent in Caucasian, Asian, and Middle Eastern populations, they are rare in both native African populations and those of African descent. The objective of this paper is to review the current knowledge regarding the epidemiology and genetics of hearing loss in African populations with a focus on native sub-Saharan African populations. Environmental etiologies related to poor access to healthcare and perinatal care account for the majority of cases. Syndromic etiologies including Waardenburg, Pendred and Usher syndromes are uncommon causes of hearing loss in these populations. Of the non-syndromic causes, common mutations in GJB2 and GJB6 are rarely implicated in populations of African descent. Recent use of next-generation sequencing(NGS) has identified several candidate deafness genes in African populations from Nigeria and South Africa that are unique when compared to common causative mutations worldwide. Researchers also recently described a dominant mutation in MYO3α in an African American family with non-syndromic hearing loss. The use of NGS and specialized panels will aid in identifying rare and novel mutations in a more cost-and timeeffective manner. The identification of common hearing loss mutations in indigenous African populations will pave the way for translation into genetic deafness research in populations of African descent worldwide.展开更多
In recent years,with the growth in Unmanned Aerial Vehicles(UAVs),UAV-based systems have become popular in both military and civil applications.In these scenarios,the lack of reliable communication infrastructure has ...In recent years,with the growth in Unmanned Aerial Vehicles(UAVs),UAV-based systems have become popular in both military and civil applications.In these scenarios,the lack of reliable communication infrastructure has motivated UAVs to establish a network as flying nodes,also known as Flying Ad Hoc Networks(FANETs).However,in FANETs,the high mobility degree of flying and terrestrial users may be responsible for constant changes in the network topology,making end-to-end connections in FANETs challenging.Mobility estimation and prediction of UAVs can address the challenge mentioned above since it can provide better routing planning and improve overall FANET performance in terms of continuous service availability.We thus develop a Software Defined Network(SDN)-based heterogeneous architecture for reliable communication in FANETs.In this architecture,we apply an Extended Kalman Filter(EKF)for accurate mobility estimation and prediction of UAVs.In particular,we formulate the routing problem in SDN-based Heterogeneous FANETs as a graph decision problem.As the problem is NP-hard,we further propose a Directional Particle Swarming Optimization(DPSO)approach to solve it.The extensive simulation results demonstrate that the proposed DPSO routing can exhibit superior performance in improving the goodput,packet delivery ratio,and delay.展开更多
The isothermal compression testing of Ti555211 titanium alloys was carried out at deformation temperatures from 750 to 950 ℃ in 50 ℃ intervals,with strain rate of 0.001-1.000 s-1and height reduction of 20%-60%.The e...The isothermal compression testing of Ti555211 titanium alloys was carried out at deformation temperatures from 750 to 950 ℃ in 50 ℃ intervals,with strain rate of 0.001-1.000 s-1and height reduction of 20%-60%.The effect of processing parameters（deformation temperature,strain rate and deformation degree） on the microstructure evolution and the microstructure variables was investigated.The results show that the content of primary α phase decreases with the increase in deformation temperature.The effect of strain rate on microstructure variables of isothermally compressed Ti555211 alloy is mainly dependent on the deformation temperature.The fine second α phase partly transforms to β phase due to the deformation heat effect at the high strain rate,α phase becomes globular with temperature increasing and strain rate decreasing.In contrast,α phase is refined with temperature decreasing and strain rate increasing.The deformation degree has a little influence on the grain size and the morphology of primary α phase,but the effect of deformation degree on the morphology of second α phase is significant.The larger deformation degree is in favor of the globularization of lamellar α structure.展开更多
The human myxovirus resistance 2(Mx2/Mx B)protein,a member of interferon(IFN)-inducible dynamin-like large GTPases,restricts a number of virus infections.Inhibition of these viruses occurs at poorly-defined steps afte...The human myxovirus resistance 2(Mx2/Mx B)protein,a member of interferon(IFN)-inducible dynamin-like large GTPases,restricts a number of virus infections.Inhibition of these viruses occurs at poorly-defined steps after viral entry and has a common requirement for Mx B oligomerization.However,the GTPase activity is essential for the anti-viral effects of Mx B against herpesviruses and HBV but not HIV-1.To understand the role of Mx B GTPase activity,including GTP binding and GTP hydrolysis,in restriction of HIV-1 infection,we genetically separated these two functions and evaluated their contributions to restriction.We found that both the GTP binding and hydrolysis function of Mx B involved in the restriction of HIV-1 replication.The GTPase activity of Mx B contributed to its nuclear location,interaction with nucleoporins(NUPs)and HIV-1 capsids.Furthermore,Mx B disrupted the association between NUPs and HIV-1 cores dependently upon its GTPase activity.The function of GTPase activity was therefore multi-faceted,led to fundamentally distinct mechanisms employed by wild-type Mx B and GTPase activity defective Mx B mutations to restrict HIV-1 replication.展开更多
The conformation of mono-6-O-p-nitrobenzoyl-β-cyclodextrin was studied with B3LYP/6-311g**//PM3 calculations in vacuum and in water solution. It was concluded that the p-nitrobenzoyl group of the molecule should be ...The conformation of mono-6-O-p-nitrobenzoyl-β-cyclodextrin was studied with B3LYP/6-311g**//PM3 calculations in vacuum and in water solution. It was concluded that the p-nitrobenzoyl group of the molecule should be located above the primary hydroxyls of the cyclodextrin instead of being completely enclosed by the cavity. It was proposed that the behavior might be caused by the requirement of a cis ester bond in the self-included conformation of the molecule.展开更多
The recrystallization behavior of deformed Ti40 alloy during a heat-treatment process was studied using electron backscatter dif- fraction and optical microscopy. The results show that the microstructural evolution of...The recrystallization behavior of deformed Ti40 alloy during a heat-treatment process was studied using electron backscatter dif- fraction and optical microscopy. The results show that the microstructural evolution of Ti40 alloy is controlled by the growth behavior of grain-boundary small grains during the heating process. These small grains at the grain boundaries mostly originate during the forging proc- ess because of the alloy＇s inhomogeneous deformation. During forging, the deformation first occurs in the grain-boundary region. New small recrystallized grains are separated from the parent grains when the orientation between deformation zones and parent grains exceeds a certain threshold. During the heating process, the growth of these small recrystallized grains results in a uniform grain size and a decrease in the av- erage grain size. The special recrystallization behavior of Ti40 alloy is mainly a consequence of the alloy＇s high β-stabilized elemeutal con- tent and high solution strength of the β-grains, which partially explains the poor hot working ability of Ti-V-Cr-type bum-resistant titanium alloys. Notably, this study on Ti40 bum-resistant titanium alloy yields important information related to the optimization of the microstruc- tures and mechanical properties.展开更多
The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction...The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.展开更多
Development of burn-resistant titanium alloys is the most direct way of mitigating the ignition and propagation of titanium fires in jet engines. WSTi3515S alloy（Ti–35V–15Cr–0.3Si–0.1C） is a new high alloying be...Development of burn-resistant titanium alloys is the most direct way of mitigating the ignition and propagation of titanium fires in jet engines. WSTi3515S alloy（Ti–35V–15Cr–0.3Si–0.1C） is a new high alloying beta type burn-resistant titanium alloy, belonging to Ti–V–Cr type alloys which have been made significant progress in engineering technology in the past 5 years. The physical properties of WSTi3515S burn-resistant titanium alloy such as the elastic properties and thermal properties were measured and analyzed in different conditions. The results show that both the Young＇s modulus and shear modulus of WSTi3515S alloy decrease slightly with the temperature increasing at the tested temperature range. The Poisson＇s ratio of WSTi3515S alloy is around 0.36. However, the thermal properties such as the specific heat, thermal diffusivity, thermal conductivity and thermal expansion increase with the temperature increasing, which results from the strengthening of lattice heat vibration at elevated temperature. And the room temperature density of WSTi3515S alloy is 5.295 gácm^（-3）.展开更多
基金supported by the National Natural Science Foundation of China(31900005)the Fund of Science and Technology Department of Henan Province(242102231001,242102320362,242102320157)+1 种基金the Fund of Program for Innovative Research Team(in Science and Technology)in University of Henan Province(23IRTSTHN009)Fund of Key Scientific Research Projects of Higher Education Institutions in Henan Province(22A150048)。
文摘By enhancing surface interaction between metal oxide particles and carbon-based materials,it can effectively improve Faraday capacitance and conductivity,ultimately achieving high energy density with sufficient redox reactions in supercapacitors.Through a gentle biomineralization process and subsequent thermal reduction strategy,we successfully prepared the graphene oxide(GO)wrapping mixed-valence manganese oxides(MnO_(x))and S,P self-codoped carbon matrix porous composite(MnO_(x)@SPC@reduced graphene oxide(RGO)).During the biomineralization process of engineered Pseudomonas sp.(Ml)cells,GO nanosheets functioned as the'soil'to adsorb Mn^(2+)ion and uniformly disperse biogenic Mn oxides(BMO).After undergoing annealing,the MnO_(x) nanoparticles were evenly wrapped with graphene,resulting in the creation of the MnO_(x)@SPC@RGO3 composite.This composite possesses strong C—O—Mn bond interfaces,numerous electroactive sites,and a uniform pore structure.By optimizing the synergistic interaction between the highly conductive graphene and the remarkable surface capacitance of MnO_(x),the MnO_(x)@SPC@RGO3 electrode,with its intercalation Faraday reactions mechanism of■transformations,exhibits an outstanding specific capacity(448.3 F·g^(-1)at 0.5 A·g^(-1)),multiplying performance(340.5 F·g^(-1)at10 A·g^(-1)),and cycling stability(93.8%retention after 5000 cycles).Moreover,the asymmetric all-solidstate supercapacitors of MnO_(x)@SPC@RGO3//PC exhibit an exceptional energy density of 64.8 W·h·kg^(-1)and power density of 350 W·kg^(-1),as well as a long lifespan with capacitance retention of 92.5%after10000 cycles.In conclusion,the synthetic route utilizing biomineralization and thermal reduction exhibits significant potential for exploiting high-performance electrode materials in all-solid-state supercapacitor applications.
文摘Labor education serves as an essential pathway for student development,offering comprehensive educational values in cultivating moral integrity,enhancing intellectual growth,strengthening physical fitness,and nurturing aesthetic appreciation.Using traditional poetry,a cultural gene of the Chinese nation,as a medium,students can not only expand their labor knowledge and practical skills but also gain insights into traditional virtues and strengthen cultural confidence.This paper attempts to explore innovative approaches to integrating Chinese poetry education with primary school labor education.Through in-depth analysis of current labor practices in primary schools and the innovative value of these integration pathways,the study provides innovative ideas and methods for primary school labor education.The goal is to help students deepen cultural literacy through hands-on experiences,use culture as nourishment to improve their labor literacy,and achieve the educational objective of holistic development.
基金financial support from Pre-research Project of Equipment Development Department of China(No.41422010505)the Technology Innovation Leading Program of Shanxi Province,China(No.2019CGHJ-21)。
文摘The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructural evolution and deformation mechanisms of hat-shaped specimens were revealed by electron backscattered diffraction(EBSD)method.It is found that the nucleation and expansion of adiabatic shear band(ASB)are affected by both geometric and structural factors.The increase of dislocation density,structure fragment and temperature rise in the deformation-affected regions provide basic microstructural conditions.In addition to the dislocation slips,the extension twins detected in shear region also play a critical role in microstructural fragmentation due to twin-boundaries effect.Interestingly,the sandwich structure imposes a crucial influence on ASB,which finally becomes a mature wide ASB in the dynamic deformation.However,due to much larger width,the sandwich structure in the middle of shear region is also possible to serve as favorable nucleation sites for crack initiation.
基金supported by grants from the National Institutes of Health/National Institute on Deafness and Other Communication Disorders to Xuezhong Liu (R01 DC05575,R01 DC01246,2P50DC000422-Sub-Project 6432,and R01 DC012115)the University of Pretoria RDP grant and the South African ENT Society Research Grant to RI Kabahuma
文摘Hearing loss is the most common sensorineural disorder worldwide and is associated with more than1000 mutations in more than 90 genes. While mutations in genes such as GJB2(gap-junction protein β 2)and GJB6(gap-junction protein β 6) are highly prevalent in Caucasian, Asian, and Middle Eastern populations, they are rare in both native African populations and those of African descent. The objective of this paper is to review the current knowledge regarding the epidemiology and genetics of hearing loss in African populations with a focus on native sub-Saharan African populations. Environmental etiologies related to poor access to healthcare and perinatal care account for the majority of cases. Syndromic etiologies including Waardenburg, Pendred and Usher syndromes are uncommon causes of hearing loss in these populations. Of the non-syndromic causes, common mutations in GJB2 and GJB6 are rarely implicated in populations of African descent. Recent use of next-generation sequencing(NGS) has identified several candidate deafness genes in African populations from Nigeria and South Africa that are unique when compared to common causative mutations worldwide. Researchers also recently described a dominant mutation in MYO3α in an African American family with non-syndromic hearing loss. The use of NGS and specialized panels will aid in identifying rare and novel mutations in a more cost-and timeeffective manner. The identification of common hearing loss mutations in indigenous African populations will pave the way for translation into genetic deafness research in populations of African descent worldwide.
文摘In recent years,with the growth in Unmanned Aerial Vehicles(UAVs),UAV-based systems have become popular in both military and civil applications.In these scenarios,the lack of reliable communication infrastructure has motivated UAVs to establish a network as flying nodes,also known as Flying Ad Hoc Networks(FANETs).However,in FANETs,the high mobility degree of flying and terrestrial users may be responsible for constant changes in the network topology,making end-to-end connections in FANETs challenging.Mobility estimation and prediction of UAVs can address the challenge mentioned above since it can provide better routing planning and improve overall FANET performance in terms of continuous service availability.We thus develop a Software Defined Network(SDN)-based heterogeneous architecture for reliable communication in FANETs.In this architecture,we apply an Extended Kalman Filter(EKF)for accurate mobility estimation and prediction of UAVs.In particular,we formulate the routing problem in SDN-based Heterogeneous FANETs as a graph decision problem.As the problem is NP-hard,we further propose a Directional Particle Swarming Optimization(DPSO)approach to solve it.The extensive simulation results demonstrate that the proposed DPSO routing can exhibit superior performance in improving the goodput,packet delivery ratio,and delay.
基金financially supported by the Project of Introducing Talents of Discipline to Universities (‘‘111’’ Project) (No. B08040)
文摘The isothermal compression testing of Ti555211 titanium alloys was carried out at deformation temperatures from 750 to 950 ℃ in 50 ℃ intervals,with strain rate of 0.001-1.000 s-1and height reduction of 20%-60%.The effect of processing parameters（deformation temperature,strain rate and deformation degree） on the microstructure evolution and the microstructure variables was investigated.The results show that the content of primary α phase decreases with the increase in deformation temperature.The effect of strain rate on microstructure variables of isothermally compressed Ti555211 alloy is mainly dependent on the deformation temperature.The fine second α phase partly transforms to β phase due to the deformation heat effect at the high strain rate,α phase becomes globular with temperature increasing and strain rate decreasing.In contrast,α phase is refined with temperature decreasing and strain rate increasing.The deformation degree has a little influence on the grain size and the morphology of primary α phase,but the effect of deformation degree on the morphology of second α phase is significant.The larger deformation degree is in favor of the globularization of lamellar α structure.
基金supported by the National Science Foundation of China(81271818 and 81471940 to YF,and 81471941,81871659 and 81828005 to WH)
文摘The human myxovirus resistance 2(Mx2/Mx B)protein,a member of interferon(IFN)-inducible dynamin-like large GTPases,restricts a number of virus infections.Inhibition of these viruses occurs at poorly-defined steps after viral entry and has a common requirement for Mx B oligomerization.However,the GTPase activity is essential for the anti-viral effects of Mx B against herpesviruses and HBV but not HIV-1.To understand the role of Mx B GTPase activity,including GTP binding and GTP hydrolysis,in restriction of HIV-1 infection,we genetically separated these two functions and evaluated their contributions to restriction.We found that both the GTP binding and hydrolysis function of Mx B involved in the restriction of HIV-1 replication.The GTPase activity of Mx B contributed to its nuclear location,interaction with nucleoporins(NUPs)and HIV-1 capsids.Furthermore,Mx B disrupted the association between NUPs and HIV-1 cores dependently upon its GTPase activity.The function of GTPase activity was therefore multi-faceted,led to fundamentally distinct mechanisms employed by wild-type Mx B and GTPase activity defective Mx B mutations to restrict HIV-1 replication.
文摘The conformation of mono-6-O-p-nitrobenzoyl-β-cyclodextrin was studied with B3LYP/6-311g**//PM3 calculations in vacuum and in water solution. It was concluded that the p-nitrobenzoyl group of the molecule should be located above the primary hydroxyls of the cyclodextrin instead of being completely enclosed by the cavity. It was proposed that the behavior might be caused by the requirement of a cis ester bond in the self-included conformation of the molecule.
基金partially supported by the International S&T Cooperation Program of China (ISTCP 2013DFB50180)the National Natural Science Foundation of China (Grant No.51504037)
文摘The recrystallization behavior of deformed Ti40 alloy during a heat-treatment process was studied using electron backscatter dif- fraction and optical microscopy. The results show that the microstructural evolution of Ti40 alloy is controlled by the growth behavior of grain-boundary small grains during the heating process. These small grains at the grain boundaries mostly originate during the forging proc- ess because of the alloy＇s inhomogeneous deformation. During forging, the deformation first occurs in the grain-boundary region. New small recrystallized grains are separated from the parent grains when the orientation between deformation zones and parent grains exceeds a certain threshold. During the heating process, the growth of these small recrystallized grains results in a uniform grain size and a decrease in the av- erage grain size. The special recrystallization behavior of Ti40 alloy is mainly a consequence of the alloy＇s high β-stabilized elemeutal con- tent and high solution strength of the β-grains, which partially explains the poor hot working ability of Ti-V-Cr-type bum-resistant titanium alloys. Notably, this study on Ti40 bum-resistant titanium alloy yields important information related to the optimization of the microstruc- tures and mechanical properties.
基金supported by the National Key Research and Development Program of China(2021YFB4001301)the Science and Technology Commission of Shanghai Municipality(21DZ1208600)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2021ZD105)。
文摘The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.
基金financially supported by the International Science and Technology Cooperation Program of China (No. ISTCP 2013DFR50090)the National Natural Science Foundation of China (No. 51504037)the Special Fund for Basic Scientific Research of Central Colleges,Chang’an University (No. 2014G1311088)
文摘Development of burn-resistant titanium alloys is the most direct way of mitigating the ignition and propagation of titanium fires in jet engines. WSTi3515S alloy（Ti–35V–15Cr–0.3Si–0.1C） is a new high alloying beta type burn-resistant titanium alloy, belonging to Ti–V–Cr type alloys which have been made significant progress in engineering technology in the past 5 years. The physical properties of WSTi3515S burn-resistant titanium alloy such as the elastic properties and thermal properties were measured and analyzed in different conditions. The results show that both the Young＇s modulus and shear modulus of WSTi3515S alloy decrease slightly with the temperature increasing at the tested temperature range. The Poisson＇s ratio of WSTi3515S alloy is around 0.36. However, the thermal properties such as the specific heat, thermal diffusivity, thermal conductivity and thermal expansion increase with the temperature increasing, which results from the strengthening of lattice heat vibration at elevated temperature. And the room temperature density of WSTi3515S alloy is 5.295 gácm^（-3）.
