Soybean mosaic virus （SMV） disease is one of the most destructive viral diseases in soybean （Glycine max （L.） Merr.）. SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The so...Soybean mosaic virus （SMV） disease is one of the most destructive viral diseases in soybean （Glycine max （L.） Merr.）. SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2：3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines （nILs） derived from residual heterozygous lines （RhLs） of Qihuang 1×nannong 1138-2 were separatively used in the ifne mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene （designated RSC3Q） controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat （SSR） markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found lfanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that ifve genes （Glyma13g25730, 25750, 25950, 25970 and 26000） were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection （MaS） in resistance breeding to SMV.展开更多
The application of some semi-solid forming magnesium alloys is restricted due to their weak mechanical properties. To improve the mechanical properties, it is necessary to research the regularity and theory of semi-so...The application of some semi-solid forming magnesium alloys is restricted due to their weak mechanical properties. To improve the mechanical properties, it is necessary to research the regularity and theory of semi-solid microstructure evolution of the alloy. In this study, microstructure evolution of ZA72 alloy during the partial remelting, and the effect of holding temperature and holding time on the semi-solid microstructure evolution of ZA72 magnesium alloy were investigated by means of OM, SEM and EDS analysis. The results indicate that the microstructure with small and spheroidal semi-solid particles which are available for thixo-forming can be obtained using proper heating parameters. After being isothermally treated at between 580 and 610 ℃ for 30 min, the equivalent size and shape factor of primary solid phase of ZA72 alloy decrease gradually, while the liquid volume fraction increases. When isothermally treated at 600 ℃ and held for different times from 15 to 60 min, with the increase of holding time, the equivalent size of primary particles decreases at first and then increases gradually; while the shape factor decreases gradually. The best heat treatment parameters in this experiment are to hold at 610 ℃for 30 min. Compared with as-cast ZA72 alloy, the sizes of the eutectic phase and second a-Mg phase obtained in semi-solid state are smaller due to the higher solidification rate and the higher under-cooling degree than as-cast state. These decrease the fracture probability during tensile stress and improve the properties of the ZA72 alloy by semi-solid forming.展开更多
Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Datun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian...Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Datun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the special natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.展开更多
Soybean mosaic virus （SMV） is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and...Soybean mosaic virus （SMV） is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively. Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China. In this study, crosses were made between Qihuang l^Kefeng 1 and DabaimaxNannong 1138-2. Ten simple sequence repeat （SSR） markers linked to three resistance loci （Rsc4, Rsc8, and Rsc^4Q） were used to assist pyramided breeding. Pyramided families containing three resistance loci （Rsc4, Rsc8, and Rsc14Q） were evaluated by inoculating them with 21 SMV strains from China. Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing Rsc4, Rsc8, and Rsc14Q. A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV. Five F7 homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection. The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.展开更多
The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The ...The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The corresponding gene SlWUS is yet to be characterized in tomato.In order to characterize SlWUS gene and its biological function,we cloned it from tomato and analyzed its structure.Tissue expression showed that the SlWUS highly expressed in tomato flower abscission zone.The overexpression of SlWUS in Arabidopsis could trigger undifferentiation of plant flower organ and indeterminacy of flower identity,suggesting that SlWUS maybe involved in flower structure development as well as flower organ identity.Taken together,our results indicated that the SlWUS plays an important role in flower abscission zone and plant organ shedding.展开更多
Resin-bonded, Al-containing magnesia refractories have been an alternative of rebonded fused-grains magchrome bricks to be used as inner lining in the snorkels and lower vessel of RH degassers, having the advantages o...Resin-bonded, Al-containing magnesia refractories have been an alternative of rebonded fused-grains magchrome bricks to be used as inner lining in the snorkels and lower vessel of RH degassers, having the advantages of being chrome-free and energy-saving(without burning), with a comparable performance. Microstructural investigations indicate that metal Al powder remains independent in the matrix after heating at 700 ℃ and 900 ℃, and Al_4C_3, Al_2OC and Al_4O_4C crystalline whiskers start forming from 1 100 ℃. The whiskers grow and connect into a network matrix with increasing temperatures,remaining up to 1 600 ℃. Comparison of used bricks from different snorkels indicates a strong whisker networks formation in the brick achieving long service life and superior performance, which is attributed to flexible network structure of stable and interwoven whiskers. On contrary, there is a strongly-oxidized layer on the hot face and almost no whisker found anywhere in the brick with the short service life. It is vital to form the bonding phase of whiskers at high temperatures,generating overall properties of high hot strength, high erosion resistance and thermal shock resistance, which are essential in the working conditions of RH snorkels.展开更多
The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO_(3)were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed...The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO_(3)were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed.The results indicate that increasing addition temperature of MgCO_(3)or pouring temperature is beneficial for obtaining fine grains.There is an optimal addition amount of 1.2%at the addition temperature of 790°C.Prolonging holding time at 790°C will increase grain size.The grain refining technique that 1.2%MgCO_(3)is added at 790°C followed by holding for 10 min and pouring can decrease the grain size from 348μm of the un-refined alloy to 69μm.The nucleation substrates are actually the Al4C3 particles formed from reactions between the MgCO_(3)and alloying elements in the melt.Besides the heterogeneous nucleation regime,growth restriction of the Al4C3 particles agglomerated at growing front is the other mechanism.展开更多
It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magne...It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magnesite.In this paper,95%MgO magnesite was used as the starting material and finally magnesia of high density(3.47 g/cm^3)and high purity(98%MgO)was obtained after the flotation purification and a three-step sintering process.An industrial scale of the beneficiation system of natural magnesite was introduced for magnesite purification.In lab experimental,the three-step sintering process was implemented by calcining,hydrating,re-calcining and sintering,which has proven the possibility of densified magnesia from natural magnesite.展开更多
基金supported by the National Natural Science Foundation of China (31171574, 31371646)the National Soybean Industrial Technology System of China (CARS-004)the Fund for Transgenic Breeding of Soybean Resistant to Soybean Mosaic Virus, China (2008ZX08004-004)
文摘Soybean mosaic virus （SMV） disease is one of the most destructive viral diseases in soybean （Glycine max （L.） Merr.）. SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2：3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines （nILs） derived from residual heterozygous lines （RhLs） of Qihuang 1×nannong 1138-2 were separatively used in the ifne mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene （designated RSC3Q） controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat （SSR） markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found lfanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that ifve genes （Glyma13g25730, 25750, 25950, 25970 and 26000） were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection （MaS） in resistance breeding to SMV.
基金supported by the National Basic Research Program of China (grant No. 2010CB635106)the High School Basic Scientific Research Program of Gansu Province
文摘The application of some semi-solid forming magnesium alloys is restricted due to their weak mechanical properties. To improve the mechanical properties, it is necessary to research the regularity and theory of semi-solid microstructure evolution of the alloy. In this study, microstructure evolution of ZA72 alloy during the partial remelting, and the effect of holding temperature and holding time on the semi-solid microstructure evolution of ZA72 magnesium alloy were investigated by means of OM, SEM and EDS analysis. The results indicate that the microstructure with small and spheroidal semi-solid particles which are available for thixo-forming can be obtained using proper heating parameters. After being isothermally treated at between 580 and 610 ℃ for 30 min, the equivalent size and shape factor of primary solid phase of ZA72 alloy decrease gradually, while the liquid volume fraction increases. When isothermally treated at 600 ℃ and held for different times from 15 to 60 min, with the increase of holding time, the equivalent size of primary particles decreases at first and then increases gradually; while the shape factor decreases gradually. The best heat treatment parameters in this experiment are to hold at 610 ℃for 30 min. Compared with as-cast ZA72 alloy, the sizes of the eutectic phase and second a-Mg phase obtained in semi-solid state are smaller due to the higher solidification rate and the higher under-cooling degree than as-cast state. These decrease the fracture probability during tensile stress and improve the properties of the ZA72 alloy by semi-solid forming.
基金Project BK2008128 supported by the Natural Science Foundation of Jiangsu Province
文摘Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Datun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the special natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.
基金supported by the National Natural Science Foundation of China(31571687,31571690,and 31371646)the Natural Science Foundation of Anhui Province,China(1708085MC69)+1 种基金the Jiangsu Collaborative Innovation Center for Modern Crop Production,China(JCIC-MCP)the Fund of Transgenic Breeding for Soybean Resistance to Soybean Mosaic Virus,China(2016ZX08004-004)
文摘Soybean mosaic virus （SMV） is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively. Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China. In this study, crosses were made between Qihuang l^Kefeng 1 and DabaimaxNannong 1138-2. Ten simple sequence repeat （SSR） markers linked to three resistance loci （Rsc4, Rsc8, and Rsc^4Q） were used to assist pyramided breeding. Pyramided families containing three resistance loci （Rsc4, Rsc8, and Rsc14Q） were evaluated by inoculating them with 21 SMV strains from China. Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing Rsc4, Rsc8, and Rsc14Q. A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV. Five F7 homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection. The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.
基金supported by the National Natural Science Foundation of China(30670188)the National Key Project for Researches on Transgenic Plant of China(2009ZX08002-011B)the Education Department Project Of Henan Province,China(2010B210015)
文摘The homeobox transcription factor WUSCHEL(WUS)plays a critical role in keeping the balance between the maintenance and differentiation of stem cell population in shoot and floral meristems of Arabidopsis thaliana.The corresponding gene SlWUS is yet to be characterized in tomato.In order to characterize SlWUS gene and its biological function,we cloned it from tomato and analyzed its structure.Tissue expression showed that the SlWUS highly expressed in tomato flower abscission zone.The overexpression of SlWUS in Arabidopsis could trigger undifferentiation of plant flower organ and indeterminacy of flower identity,suggesting that SlWUS maybe involved in flower structure development as well as flower organ identity.Taken together,our results indicated that the SlWUS plays an important role in flower abscission zone and plant organ shedding.
文摘Resin-bonded, Al-containing magnesia refractories have been an alternative of rebonded fused-grains magchrome bricks to be used as inner lining in the snorkels and lower vessel of RH degassers, having the advantages of being chrome-free and energy-saving(without burning), with a comparable performance. Microstructural investigations indicate that metal Al powder remains independent in the matrix after heating at 700 ℃ and 900 ℃, and Al_4C_3, Al_2OC and Al_4O_4C crystalline whiskers start forming from 1 100 ℃. The whiskers grow and connect into a network matrix with increasing temperatures,remaining up to 1 600 ℃. Comparison of used bricks from different snorkels indicates a strong whisker networks formation in the brick achieving long service life and superior performance, which is attributed to flexible network structure of stable and interwoven whiskers. On contrary, there is a strongly-oxidized layer on the hot face and almost no whisker found anywhere in the brick with the short service life. It is vital to form the bonding phase of whiskers at high temperatures,generating overall properties of high hot strength, high erosion resistance and thermal shock resistance, which are essential in the working conditions of RH snorkels.
基金Project(G2010CB635106)supported by the National Basic Research Program of China+1 种基金Project(NCET-10-0023)supported by the Program for New Century Excellent Talents in University of China
文摘The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO_(3)were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed.The results indicate that increasing addition temperature of MgCO_(3)or pouring temperature is beneficial for obtaining fine grains.There is an optimal addition amount of 1.2%at the addition temperature of 790°C.Prolonging holding time at 790°C will increase grain size.The grain refining technique that 1.2%MgCO_(3)is added at 790°C followed by holding for 10 min and pouring can decrease the grain size from 348μm of the un-refined alloy to 69μm.The nucleation substrates are actually the Al4C3 particles formed from reactions between the MgCO_(3)and alloying elements in the melt.Besides the heterogeneous nucleation regime,growth restriction of the Al4C3 particles agglomerated at growing front is the other mechanism.
文摘It is hard to manufacture high purity,dense sintered-magnesia from natural magnesite in the prevailing process of calcining and sintering,for two reasons:a)impurity,and b)low sintering activity of coarse-grained magnesite.In this paper,95%MgO magnesite was used as the starting material and finally magnesia of high density(3.47 g/cm^3)and high purity(98%MgO)was obtained after the flotation purification and a three-step sintering process.An industrial scale of the beneficiation system of natural magnesite was introduced for magnesite purification.In lab experimental,the three-step sintering process was implemented by calcining,hydrating,re-calcining and sintering,which has proven the possibility of densified magnesia from natural magnesite.
