The microstructure of Ti-6-4 components produced by additive manufacturing suffers from the coarse and elongated prior-β grain,which leads to a decrease of the tensile behavior and the occurrence of anisotropy.To und...The microstructure of Ti-6-4 components produced by additive manufacturing suffers from the coarse and elongated prior-β grain,which leads to a decrease of the tensile behavior and the occurrence of anisotropy.To understand and control the grain evolution,a multiscale simulation is applied to investigate the relationship between the grain selection,growth orientation,and the molten pool morphology with the different deposition layer numbers and processing parameters.The accuracy of the simulation is validated by experiments in both qualitative and quantitative ways.Results show that when the grain with unfavorable orientation loses the competitive growth with its neighbors,there will be a great chance that the blocked grain is eliminated in the following layer-and-layer deposition,which leads to the increase of the grain width.The size of the molten pool increases remarkably as the layer number increases,which lays a heavy burden on the stability of the molten pool.The analytical relationship between the molten pool morphology and the grain growth orientation is also deduced.The flat molten pool causes the grains with the <001> direction close to the building direction to have greater survival potential.Besides,decreasing the line power energy shows little effect on the stability of the molten pool and the grain growth orientation,especially when the deposited layer number is large.The revealing mechanisms will help in understanding and further controlling the grain evolution.展开更多
Powdery mildew, caused by Blumeria graminis f. sp. tritici(Bgt), is one of the most devastating diseases of common wheat(Triticum aestivum L.). The wheat line 92145 E8-9 is immune to Bgt isolate E09. Genetic analysis ...Powdery mildew, caused by Blumeria graminis f. sp. tritici(Bgt), is one of the most devastating diseases of common wheat(Triticum aestivum L.). The wheat line 92145 E8-9 is immune to Bgt isolate E09. Genetic analysis reveals that the powdery mildew resistance in 92145 E8-9 is controlled by a single dominant gene, temporarily designated Ml92145 E8-9. Bulkedsegregant analysis(BSA) with simple sequence repeat(SSR) markers indicates that Ml92145 E8-9 is located on chromosome 2 AL. According to the reactions of 92145 E8-9,VPM1(Pm4 b carrier), and Lankao 906(PmLK906 carrier) to 14 Bgt isolates, the resistance spectrum of 92145 E8-9 differs from those of Pm4 b and PmLK906, both of which were previously localized to 2 AL. To test the allelism among Ml92145 E8-9, Pm4 b and PmLK906, two F2 populations of 92145 E8-9 × VPM1(Pm4 b) and 92145 E8-9 × Lankao 906(PmLK906) were developed in this study. Screening of 784 F2 progeny of 92145 E8-9 × VPM1 and 973 F2 progeny of 92145 E8-9 × Lankao 906 for Bgt isolate E09 identified 37 and 19 susceptible plants, respectively. These findings indicated that Ml92145 E8-9 is non-allelic to either Pm4 b or PmLK906. Thus, Ml92145 E8-9 is likely to be a new powdery mildew resistance gene on2 AL. New polymorphic markers were developed based on the collinearity of genomic regions of Ml92145 E8-9 with the reference sequences of the International Wheat Genome Sequencing Consortium(IWGSC). Ml92145 E8-9 was mapped to a 3.6 c M interval flanked by molecular markers Xsdauk13 and Xsdauk682. This study also developed five powdery mildew-resistant wheat lines(SDAU3561, SDAU3562, SDAU4173, SDAU4174, and SDAU4175)using flanking marker-aided selection. The markers closely linked to Ml92145 E8-9 would be useful in marker-assisted selection for wheat powdery mildew resistance breeding.展开更多
Edible sunflower variety AR9-9293 was approved by the Sunflower Variety Appraisal Committee with the country Identification number of sunflower 2015005. This paper introduced the breeding process, yield performance an...Edible sunflower variety AR9-9293 was approved by the Sunflower Variety Appraisal Committee with the country Identification number of sunflower 2015005. This paper introduced the breeding process, yield performance and characteristics, and the high-yield cultivation technology of new edible sunflower variety AR9-9293. The promotion of edible sunflower varieties and cultivation technology could achieve the effects of improving the level of the sunflower cultivation, promoting the development of rural and agricultural economy and increasing farmers' income, as well as positively promoting development of the society and adjusting agricultural industry structure.展开更多
建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取,4℃冷藏后,采用分散型固相萃取法净化,由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证...建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取,4℃冷藏后,采用分散型固相萃取法净化,由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证,同位素内标法定量。在1~40μg / L 范围内氟乐灵农药的线性关系良好;方法定量限(LOQ)为0.02μg / kg;对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验,平均回收率均处于80%~100%之间,RSD≤10.3%;无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。展开更多
Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (...Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods, H-NMR and MS. This technology belongs to the modern concept of 1 environmentally friendly low wastes or non-wastes technology (LWNWT).展开更多
Extracting, transportation and the using from fossil fuels can damage to the hydrosphere, the biosphere and the Earth's atmosphere. But humans always need to this valuable substance. The production of oil derivatives...Extracting, transportation and the using from fossil fuels can damage to the hydrosphere, the biosphere and the Earth's atmosphere. But humans always need to this valuable substance. The production of oil derivatives by means of forest waste and coal through the Fischer-Tropsch process is an appropriate solution for the cleanliness of all parts of the environment. For the production of favorite products by the synthesis of Fischer-Tropsch, the performance of the catalyst under different operating conditions should be predictable. For this reason, in this paper, eight mathematical models were determined for the selectivity of five products of methane, light hydrocarbons, gasoline, diesel and wax based on three factors of reduction temperature, time on stream, and He/CO ratio inlet gas on iron-based catalyst. The results showed that the reduction temperature factor had the most effective on the selectivity of hydrocarbon products, exception diesel, so that the increase of the reduction temperature led to increase of the selectivity of methane, light hydrocarbons, gasoline and reduce of the degree of selectivity of the wax and vice versa. For the diesel selectivity, factor of the He/CO ratio inlet gas was the most effective than other factors.展开更多
Comparatively high CH3OH selectivity (60.0%) and yield (6.7%) were obtained on MoOx/(LaCoO3+Co3O4) catalysts in selective oxidation of methane to methanol using molecular oxygen as oxidant. The interaction between MoO...Comparatively high CH3OH selectivity (60.0%) and yield (6.7%) were obtained on MoOx/(LaCoO3+Co3O4) catalysts in selective oxidation of methane to methanol using molecular oxygen as oxidant. The interaction between MoOx and La-Co-oxide modified the molecular structure of molybdenum oxide and the ratio of O7O ' on the catalyst surface, which controlled the catalytic performance of MoOx/(LaCoO3+Co3O4) catalysts.展开更多
The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of impro...The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of improved Support Vector Machine based on 1-norm(1-SVM) is provided from the optimization problem, yet it is a discrete programming. With the smoothing technique and optimality knowledge, the discrete programming is changed into a continuous programming. Experimental results show that the algorithm is easy to implement and this method can select and suppress the problem features more efficiently. Illustrative examples show that the 1-SVM deal with the linear or nonlinear classification well.展开更多
Diisopropylidenated α-D-glucofuranose (1) was oxidated with CrO3-pyridine complex. Oxidated product and its hydrate were separated and were reduced together to synthesize diisopropylidenated α-D-allofuranose ( 3...Diisopropylidenated α-D-glucofuranose (1) was oxidated with CrO3-pyridine complex. Oxidated product and its hydrate were separated and were reduced together to synthesize diisopropylidenated α-D-allofuranose ( 3). The yield of 3 increased by 8% than that with only oxidated product as reduction substrate. Benzoylated derivative of 3 was selectively nydrolyzed and dimesylated to synthesize 3-O-benzoyl-1 .2- O- isopropylidene-α-D-allofuranose ( 5 ) and its dimesylated derivative respectively. The overall yield of 5 from 1 was 36%. Each step and final products were analyzed by ^1H-NMR spectra and other methods. The experiments showed that the influence of acetic acid concentration on selective hydrolysis was obvious. The hydrolysis yield was 81.8%. Oxidation. reduction and other procedures were practical and had application potential.展开更多
17-4 precipitation-hardened(PH)stainless steel(SS)exhibits high strength and good corrosion resistance via Cu-precipitation hardening.Unlike conventional wrought 17-4PH SS,Cu segregation andε-Cu pre-cipitates are obs...17-4 precipitation-hardened(PH)stainless steel(SS)exhibits high strength and good corrosion resistance via Cu-precipitation hardening.Unlike conventional wrought 17-4PH SS,Cu segregation andε-Cu pre-cipitates are observed in additively manufactured(AM)17-4PH SS owing to the repeated rapid cooling after heating,which characterizes the AM process.In this study,solution treatment was conducted under various temperatures(1,000,1,050,1,100,and 1,200℃)and durations(1,2,4,and 8 h)to minimize the negative effects of Cu segregation andε-Cu precipitates on precipitation hardening.The mechanical prop-erties and microstructures of each condition for the Cu precipitation behavior were examined.Although theε-Cu precipitates did not disappear after solution treatment,the average diameter of theε-Cu precipi-tates tended to decrease with increasing solution treatment temperature and duration.Therefore,solution treatment at a temperature of 1,200℃ for 8 h was the best,resulting in improved strength compared to the conventional solution treatment at 1,050℃.Solution treatment on at least 1,100℃ is effective in AM.展开更多
Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans i...Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans is a critical pathogenic microorganism that causes dental caries.This work investigated the corrosive effects of S.mutans on TC4 and functional gradient TC4/TC4-5Cu coupons fabricated by selective laser melting(SLM)through various electrochemical measurements,surface examination,observation of biofilm and corrosion analysis.The results indicated that the Cu-bearing alloy showed an inhibitory effect on the biofilms due to the release of Cu element,thereby reducing the corrosion rate of MIC.The corrosion current density(icorr)of TC4(11.7±0.8)nA cm−2 is higher than that of TC4/TC4-5Cu(7.4±0.4)nA cm−2 in the presence of S.mutans,while the maximum pit depth of TC4 is 1.6 times that of TC4/TC4-5Cu.Therefore,metal modification through Cu alloying is an effective strategy to improve the MIC resistance.展开更多
A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional (3D) printing (AM/3DP) by n...A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional (3D) printing (AM/3DP) by numerical simulation, using a finite volume method (FVM). The influence of the applied linear energy density (LED) on dimensions of the molten pool, thermodynamic mechanisms within the pool, bubbles migration and resultant densification behavior of AM/3DP-processed superalloy has been discussed. It reveals that the center of the molten pool slightly shifts with a lagging of 4 ktm towards the center of the moving laser beam. The Mar- angoni convection, which has various flow patterns, plays a crucial role in intensifying the convective heat and mass transfer, which is responsible for the bubbles migration and densification behavior of AM/3DP-processed parts. At an optimized LED of 221.5 J/m, the outward convection favors the numerous bubbles to escape from the molten pool easily and the resultant considerably high relative density of 98.9 % is achieved. However, as the applied LED further increases over 249.5 J/m, the convection pattern is apparently intensified with the formation of vortexes and the bubbles tend to be entrapped by the rotating flow within the molten pool, resulting in a large amount of residual porosity and a sharp reduction in densification of the superalloy. The change rules of the relative density and the corresponding distribution of porosity obtained by experiments are in accordance with the simulation results.展开更多
NOx emission abatement catalysts V 2O 5 supported on various TiO 2 including anatase, rutile and mixture of both were investigated with various physico\|chemical measurements such as BET, NH\-3\|TPD, NARP, XRD and ...NOx emission abatement catalysts V 2O 5 supported on various TiO 2 including anatase, rutile and mixture of both were investigated with various physico\|chemical measurements such as BET, NH\-3\|TPD, NARP, XRD and so on, and the effect of TiO\-2 surface properties on the SCR(selective catalytic reduction) activity of V\-2O\-5/TiO\-2 catalysts was studied. It was found that the TiO\-2 surface properties had strong affect on the SCR activity of V\-2O\-5/TiO\-2 catalysts. The stronger acidic property resulted in the higher exposure of active sites as well as the higher SCR activity.展开更多
基金supported by the National Key Research and Development Program of China (No. 2017YFB1103700)the National Natural Science Foundation of China (No. 51575304 and No. 51674153)。
文摘The microstructure of Ti-6-4 components produced by additive manufacturing suffers from the coarse and elongated prior-β grain,which leads to a decrease of the tensile behavior and the occurrence of anisotropy.To understand and control the grain evolution,a multiscale simulation is applied to investigate the relationship between the grain selection,growth orientation,and the molten pool morphology with the different deposition layer numbers and processing parameters.The accuracy of the simulation is validated by experiments in both qualitative and quantitative ways.Results show that when the grain with unfavorable orientation loses the competitive growth with its neighbors,there will be a great chance that the blocked grain is eliminated in the following layer-and-layer deposition,which leads to the increase of the grain width.The size of the molten pool increases remarkably as the layer number increases,which lays a heavy burden on the stability of the molten pool.The analytical relationship between the molten pool morphology and the grain growth orientation is also deduced.The flat molten pool causes the grains with the <001> direction close to the building direction to have greater survival potential.Besides,decreasing the line power energy shows little effect on the stability of the molten pool and the grain growth orientation,especially when the deposited layer number is large.The revealing mechanisms will help in understanding and further controlling the grain evolution.
基金financially supported by Geneti-cally Modified Organisms Breeding Major Projects(2016ZX08009003-001-006)the National Natural Science Foundation of China(31471488 and 31520203911)the National Basic Research Program of China(2014CB138100)
文摘Powdery mildew, caused by Blumeria graminis f. sp. tritici(Bgt), is one of the most devastating diseases of common wheat(Triticum aestivum L.). The wheat line 92145 E8-9 is immune to Bgt isolate E09. Genetic analysis reveals that the powdery mildew resistance in 92145 E8-9 is controlled by a single dominant gene, temporarily designated Ml92145 E8-9. Bulkedsegregant analysis(BSA) with simple sequence repeat(SSR) markers indicates that Ml92145 E8-9 is located on chromosome 2 AL. According to the reactions of 92145 E8-9,VPM1(Pm4 b carrier), and Lankao 906(PmLK906 carrier) to 14 Bgt isolates, the resistance spectrum of 92145 E8-9 differs from those of Pm4 b and PmLK906, both of which were previously localized to 2 AL. To test the allelism among Ml92145 E8-9, Pm4 b and PmLK906, two F2 populations of 92145 E8-9 × VPM1(Pm4 b) and 92145 E8-9 × Lankao 906(PmLK906) were developed in this study. Screening of 784 F2 progeny of 92145 E8-9 × VPM1 and 973 F2 progeny of 92145 E8-9 × Lankao 906 for Bgt isolate E09 identified 37 and 19 susceptible plants, respectively. These findings indicated that Ml92145 E8-9 is non-allelic to either Pm4 b or PmLK906. Thus, Ml92145 E8-9 is likely to be a new powdery mildew resistance gene on2 AL. New polymorphic markers were developed based on the collinearity of genomic regions of Ml92145 E8-9 with the reference sequences of the International Wheat Genome Sequencing Consortium(IWGSC). Ml92145 E8-9 was mapped to a 3.6 c M interval flanked by molecular markers Xsdauk13 and Xsdauk682. This study also developed five powdery mildew-resistant wheat lines(SDAU3561, SDAU3562, SDAU4173, SDAU4174, and SDAU4175)using flanking marker-aided selection. The markers closely linked to Ml92145 E8-9 would be useful in marker-assisted selection for wheat powdery mildew resistance breeding.
文摘Edible sunflower variety AR9-9293 was approved by the Sunflower Variety Appraisal Committee with the country Identification number of sunflower 2015005. This paper introduced the breeding process, yield performance and characteristics, and the high-yield cultivation technology of new edible sunflower variety AR9-9293. The promotion of edible sunflower varieties and cultivation technology could achieve the effects of improving the level of the sunflower cultivation, promoting the development of rural and agricultural economy and increasing farmers' income, as well as positively promoting development of the society and adjusting agricultural industry structure.
文摘建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取,4℃冷藏后,采用分散型固相萃取法净化,由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证,同位素内标法定量。在1~40μg / L 范围内氟乐灵农药的线性关系良好;方法定量限(LOQ)为0.02μg / kg;对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验,平均回收率均处于80%~100%之间,RSD≤10.3%;无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。
文摘Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods, H-NMR and MS. This technology belongs to the modern concept of 1 environmentally friendly low wastes or non-wastes technology (LWNWT).
文摘Extracting, transportation and the using from fossil fuels can damage to the hydrosphere, the biosphere and the Earth's atmosphere. But humans always need to this valuable substance. The production of oil derivatives by means of forest waste and coal through the Fischer-Tropsch process is an appropriate solution for the cleanliness of all parts of the environment. For the production of favorite products by the synthesis of Fischer-Tropsch, the performance of the catalyst under different operating conditions should be predictable. For this reason, in this paper, eight mathematical models were determined for the selectivity of five products of methane, light hydrocarbons, gasoline, diesel and wax based on three factors of reduction temperature, time on stream, and He/CO ratio inlet gas on iron-based catalyst. The results showed that the reduction temperature factor had the most effective on the selectivity of hydrocarbon products, exception diesel, so that the increase of the reduction temperature led to increase of the selectivity of methane, light hydrocarbons, gasoline and reduce of the degree of selectivity of the wax and vice versa. For the diesel selectivity, factor of the He/CO ratio inlet gas was the most effective than other factors.
基金supported by the State Key Fundamental Research Development Project(G1999022404)
文摘Comparatively high CH3OH selectivity (60.0%) and yield (6.7%) were obtained on MoOx/(LaCoO3+Co3O4) catalysts in selective oxidation of methane to methanol using molecular oxygen as oxidant. The interaction between MoOx and La-Co-oxide modified the molecular structure of molybdenum oxide and the ratio of O7O ' on the catalyst surface, which controlled the catalytic performance of MoOx/(LaCoO3+Co3O4) catalysts.
基金Supported Partially by National Science Foundation of China (No.10571109,60573018)Science & Technology Research Project of Shanxi Higher-Education (No.20051277)
文摘The model of optimization problem for Support Vector Machine(SVM) is provided, which based on the definitions of the dual norm and the distance between a point and its projection onto a given plane. The model of improved Support Vector Machine based on 1-norm(1-SVM) is provided from the optimization problem, yet it is a discrete programming. With the smoothing technique and optimality knowledge, the discrete programming is changed into a continuous programming. Experimental results show that the algorithm is easy to implement and this method can select and suppress the problem features more efficiently. Illustrative examples show that the 1-SVM deal with the linear or nonlinear classification well.
基金Supported by Tianjin Natural Science Foundation ( No. 05YFJMJC09600).
文摘Diisopropylidenated α-D-glucofuranose (1) was oxidated with CrO3-pyridine complex. Oxidated product and its hydrate were separated and were reduced together to synthesize diisopropylidenated α-D-allofuranose ( 3). The yield of 3 increased by 8% than that with only oxidated product as reduction substrate. Benzoylated derivative of 3 was selectively nydrolyzed and dimesylated to synthesize 3-O-benzoyl-1 .2- O- isopropylidene-α-D-allofuranose ( 5 ) and its dimesylated derivative respectively. The overall yield of 5 from 1 was 36%. Each step and final products were analyzed by ^1H-NMR spectra and other methods. The experiments showed that the influence of acetic acid concentration on selective hydrolysis was obvious. The hydrolysis yield was 81.8%. Oxidation. reduction and other procedures were practical and had application potential.
基金This work was funded by Yangyoung Foundation and supported by the Technology Innovation Program(grant No.20009815,Development of DfAM-based 3D printing technology for lightweight and integrated aerospace parts)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘17-4 precipitation-hardened(PH)stainless steel(SS)exhibits high strength and good corrosion resistance via Cu-precipitation hardening.Unlike conventional wrought 17-4PH SS,Cu segregation andε-Cu pre-cipitates are observed in additively manufactured(AM)17-4PH SS owing to the repeated rapid cooling after heating,which characterizes the AM process.In this study,solution treatment was conducted under various temperatures(1,000,1,050,1,100,and 1,200℃)and durations(1,2,4,and 8 h)to minimize the negative effects of Cu segregation andε-Cu precipitates on precipitation hardening.The mechanical prop-erties and microstructures of each condition for the Cu precipitation behavior were examined.Although theε-Cu precipitates did not disappear after solution treatment,the average diameter of theε-Cu precipi-tates tended to decrease with increasing solution treatment temperature and duration.Therefore,solution treatment at a temperature of 1,200℃ for 8 h was the best,resulting in improved strength compared to the conventional solution treatment at 1,050℃.Solution treatment on at least 1,100℃ is effective in AM.
基金supported by the National Natural Science Foundation of China(No.52301091)the Medical Engineering Intersection Joint Funds of the Natural Science Foundation of Liaoning Province of China(No.2022-YGJC-01).
文摘Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans is a critical pathogenic microorganism that causes dental caries.This work investigated the corrosive effects of S.mutans on TC4 and functional gradient TC4/TC4-5Cu coupons fabricated by selective laser melting(SLM)through various electrochemical measurements,surface examination,observation of biofilm and corrosion analysis.The results indicated that the Cu-bearing alloy showed an inhibitory effect on the biofilms due to the release of Cu element,thereby reducing the corrosion rate of MIC.The corrosion current density(icorr)of TC4(11.7±0.8)nA cm−2 is higher than that of TC4/TC4-5Cu(7.4±0.4)nA cm−2 in the presence of S.mutans,while the maximum pit depth of TC4 is 1.6 times that of TC4/TC4-5Cu.Therefore,metal modification through Cu alloying is an effective strategy to improve the MIC resistance.
基金supported by the National Natural Science Foundation of China (51575267, 51322509)the Top-Notch Young Talents Program of China+9 种基金the Outstanding Youth Foundation of Jiangsu Province of China (BK20130035)the Program for New Century Excellent Talents in University (NCET-13-0854)the Science and Technology Support Program (the Industrial Part)Jiangsu Provincial Department of Science and Technology of China (BE2014009-2)the 333 high-level talents training project (BRA2015368)the Science and Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Human Resources and Social Security of Chinathe Aeronautical Science Foundation of China (2015ZE52051)the Shanghai Aerospace Science and Technology Innovation Fund (SAST2015053)the Fundamental Research Funds for the Central Universities (NE2013103, NP2015206 and NZ2016108)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional (3D) printing (AM/3DP) by numerical simulation, using a finite volume method (FVM). The influence of the applied linear energy density (LED) on dimensions of the molten pool, thermodynamic mechanisms within the pool, bubbles migration and resultant densification behavior of AM/3DP-processed superalloy has been discussed. It reveals that the center of the molten pool slightly shifts with a lagging of 4 ktm towards the center of the moving laser beam. The Mar- angoni convection, which has various flow patterns, plays a crucial role in intensifying the convective heat and mass transfer, which is responsible for the bubbles migration and densification behavior of AM/3DP-processed parts. At an optimized LED of 221.5 J/m, the outward convection favors the numerous bubbles to escape from the molten pool easily and the resultant considerably high relative density of 98.9 % is achieved. However, as the applied LED further increases over 249.5 J/m, the convection pattern is apparently intensified with the formation of vortexes and the bubbles tend to be entrapped by the rotating flow within the molten pool, resulting in a large amount of residual porosity and a sharp reduction in densification of the superalloy. The change rules of the relative density and the corresponding distribution of porosity obtained by experiments are in accordance with the simulation results.
文摘NOx emission abatement catalysts V 2O 5 supported on various TiO 2 including anatase, rutile and mixture of both were investigated with various physico\|chemical measurements such as BET, NH\-3\|TPD, NARP, XRD and so on, and the effect of TiO\-2 surface properties on the SCR(selective catalytic reduction) activity of V\-2O\-5/TiO\-2 catalysts was studied. It was found that the TiO\-2 surface properties had strong affect on the SCR activity of V\-2O\-5/TiO\-2 catalysts. The stronger acidic property resulted in the higher exposure of active sites as well as the higher SCR activity.