Two yield-enhancing genes (yld1.1 and yld2.1) are located on chromosomes 1 and 2 respectivelyin a weedy relative of cultivated rice, Oryza rufipogon. SSR markers RM9 and RM166 are closelylinked with the two loci respe...Two yield-enhancing genes (yld1.1 and yld2.1) are located on chromosomes 1 and 2 respectivelyin a weedy relative of cultivated rice, Oryza rufipogon. SSR markers RM9 and RM166 are closelylinked with the two loci respectively. Minghui63 (MH63) has been a widely used restorationline in hybrid rice production in China during the past two decades. The F1 of cross 'MH63O.rufipogon' was backcrossed with MH63 generation by generation. RM9 and RM166 were used toselect the plants from the progeny of the backcross populations. The results were as follows:(1) In BC2F1 population, the percentage of the individuals which have RM9 and RM166 amplifiedbands simultaneously was 12.2%, while in the BC3F1 population, that was 16.3%. (2) Among 400individuals of BC3F1, four yield-promising plants were obtained, with yield being 30% more thanthat of MH63. (3) The products amplified by primer RM166 in O. rufipogon and MH63 weresequenced. It was found that the DNA fragment sequence amplified by RM166 from MH63 was 101 bpshorter than that from O. rufipogon. The 101bp sequence is a part of an intron of the PCNA(proliferating cell nuclear antigen) gene.展开更多
Al2O3+13wt%TiO2 (AT13) particles were doped with 5%～30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying te...Al2O3+13wt%TiO2 (AT13) particles were doped with 5%～30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration. The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3) 5.333 and orthorhombic Al2TiO5 were identified . The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100～200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.展开更多
A spontaneously occurring rice (Oryza sativa L.) mutant, characterized by homeotic conversionin glumes and stamens, was found in the progeny of a cross. The mutant showed long glumes andglumaceous lodicules and morpho...A spontaneously occurring rice (Oryza sativa L.) mutant, characterized by homeotic conversionin glumes and stamens, was found in the progeny of a cross. The mutant showed long glumes andglumaceous lodicules and morphological transformation of stamens into pistils. Mutant floretsconsisted of 1 to 3 completely developed pistils, some pistilloid stamens with filaments, buttipped by bulged tissue and 0 to 3 stigmas. It seems that the mutant phenotype of the homeoticconversions in glumes and stamens is similar to that of the B loss-of-function mutants inArabidopsis and Antirrhinum. The mutant is controlled by a single recessive gene as asegregation ratio of 3:1 (wild type to mutant plants) was observed in the F2 generation.展开更多
It is more and more important to create new genetic resources in hybrid rice breedding by using the tertiary and the forth gene pool through biotechnologic methods after the success of the utilization of inter-subspec...It is more and more important to create new genetic resources in hybrid rice breedding by using the tertiary and the forth gene pool through biotechnologic methods after the success of the utilization of inter-subspecific heterosis. We have established a simple procedure which is modified from that of Pena to transfer exogenous DAN into rice. When the recipient plant has undergone meiosis, exogenous DNA is injected into the upermost internode of a stem, the position just under the panicle base. In the next generation (D1), variants are found at a rate from 10-3to 10-1.展开更多
In peer-to-peer （P2P） video-on-demand （VoD） streaming systems, each peer contributes a fixed amount of hard disk storage （usually 2 GB） to store viewed videos and then uploads them to other requesting peers. How...In peer-to-peer （P2P） video-on-demand （VoD） streaming systems, each peer contributes a fixed amount of hard disk storage （usually 2 GB） to store viewed videos and then uploads them to other requesting peers. However, the daily hits （namely popularity） of different segments of a video is highly diverse, which means that taking the whole video as the basic storage unit may lead to redundancy of unpopular segment replicas and scarcity of popular segment replicas in the P2P storage network. To address this issue, we propose a video slicing mechanism （VSM） in which the whole video is sliced into small blocks （20 MB, for instance）. Under VSM, peers can moderately remove unpopular blocks from and accordingly add popular ones into their contributed hard disk storage, which increases the usage of peers＇ contributed resource （storage and bandwidth）. To reasonably assign bandwidth among peers with different download capacity, we propose a moderate prefetching strategy （MPS） based on VSM. Under MPS, when the amount of prefetched content reaches the predefined threshold, peers immediately stop prefetching video content and then release occupied bandwidth for others. A stochastic model is established to analyze the performance of the MPS and it is found that perfect playback continuity can be got under MPS. Then the MPS is applied to PPLive VoD system （one of the largest P2P VoD systems in China） and measurement results demonstrate that low server load and perfect user satisfaction can be achieved. Also, the server bandwidth contribution of PPLive VoD system under MPS （namely 5%） is much lower than that of UUSee VoD system （namely 30%）.展开更多
文摘Two yield-enhancing genes (yld1.1 and yld2.1) are located on chromosomes 1 and 2 respectivelyin a weedy relative of cultivated rice, Oryza rufipogon. SSR markers RM9 and RM166 are closelylinked with the two loci respectively. Minghui63 (MH63) has been a widely used restorationline in hybrid rice production in China during the past two decades. The F1 of cross 'MH63O.rufipogon' was backcrossed with MH63 generation by generation. RM9 and RM166 were used toselect the plants from the progeny of the backcross populations. The results were as follows:(1) In BC2F1 population, the percentage of the individuals which have RM9 and RM166 amplifiedbands simultaneously was 12.2%, while in the BC3F1 population, that was 16.3%. (2) Among 400individuals of BC3F1, four yield-promising plants were obtained, with yield being 30% more thanthat of MH63. (3) The products amplified by primer RM166 in O. rufipogon and MH63 weresequenced. It was found that the DNA fragment sequence amplified by RM166 from MH63 was 101 bpshorter than that from O. rufipogon. The 101bp sequence is a part of an intron of the PCNA(proliferating cell nuclear antigen) gene.
文摘Al2O3+13wt%TiO2 (AT13) particles were doped with 5%～30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration. The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3) 5.333 and orthorhombic Al2TiO5 were identified . The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100～200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.
文摘A spontaneously occurring rice (Oryza sativa L.) mutant, characterized by homeotic conversionin glumes and stamens, was found in the progeny of a cross. The mutant showed long glumes andglumaceous lodicules and morphological transformation of stamens into pistils. Mutant floretsconsisted of 1 to 3 completely developed pistils, some pistilloid stamens with filaments, buttipped by bulged tissue and 0 to 3 stigmas. It seems that the mutant phenotype of the homeoticconversions in glumes and stamens is similar to that of the B loss-of-function mutants inArabidopsis and Antirrhinum. The mutant is controlled by a single recessive gene as asegregation ratio of 3:1 (wild type to mutant plants) was observed in the F2 generation.
文摘It is more and more important to create new genetic resources in hybrid rice breedding by using the tertiary and the forth gene pool through biotechnologic methods after the success of the utilization of inter-subspecific heterosis. We have established a simple procedure which is modified from that of Pena to transfer exogenous DAN into rice. When the recipient plant has undergone meiosis, exogenous DNA is injected into the upermost internode of a stem, the position just under the panicle base. In the next generation (D1), variants are found at a rate from 10-3to 10-1.
基金supported by the National Basic Research Program of China (2007CB307101)the National Natural Science Foundation of China (60672069,60772043)
文摘In peer-to-peer （P2P） video-on-demand （VoD） streaming systems, each peer contributes a fixed amount of hard disk storage （usually 2 GB） to store viewed videos and then uploads them to other requesting peers. However, the daily hits （namely popularity） of different segments of a video is highly diverse, which means that taking the whole video as the basic storage unit may lead to redundancy of unpopular segment replicas and scarcity of popular segment replicas in the P2P storage network. To address this issue, we propose a video slicing mechanism （VSM） in which the whole video is sliced into small blocks （20 MB, for instance）. Under VSM, peers can moderately remove unpopular blocks from and accordingly add popular ones into their contributed hard disk storage, which increases the usage of peers＇ contributed resource （storage and bandwidth）. To reasonably assign bandwidth among peers with different download capacity, we propose a moderate prefetching strategy （MPS） based on VSM. Under MPS, when the amount of prefetched content reaches the predefined threshold, peers immediately stop prefetching video content and then release occupied bandwidth for others. A stochastic model is established to analyze the performance of the MPS and it is found that perfect playback continuity can be got under MPS. Then the MPS is applied to PPLive VoD system （one of the largest P2P VoD systems in China） and measurement results demonstrate that low server load and perfect user satisfaction can be achieved. Also, the server bandwidth contribution of PPLive VoD system under MPS （namely 5%） is much lower than that of UUSee VoD system （namely 30%）.
