Genetic analysis of yield and yield components were carried out on three parental clones of Coffea canephora Pierre and their controlled hybrid progenies. There is a possibility to estimate coffee yield capabilities i...Genetic analysis of yield and yield components were carried out on three parental clones of Coffea canephora Pierre and their controlled hybrid progenies. There is a possibility to estimate coffee yield capabilities in simply via the easier measuring traits of yield components since significant correlation between them were detected. We found that among parental show very few significantly differences of all observed characters and even not found between the overall mean of the descendants and their donor parents, whereas some particular descendants show higher values rather than their donor parent in one or more characters. Increased value between the best parent to the best descendent were detected varies from zero to 102%. This situation suggests the difficulty to find out the optimum yield in a single plant by accumulating all of yield components that actually can increase 143% to 278% from actual to potential yields. In addition, observed characters among population were also actually found highly varies from 159% in out-turn in population B to 28,333% in number of productive branch among population A. Low heritability （h2） that generally found in quantitative traits due to polygenic control was present in our studies in almost all characters observed. Therefore, selection for actual high yielding through conventional breeding will not efficient, and more convincing the power of selection using molecular markers to assist for cumulate additive effects in a single genotypes that resulted of high yielding in the future.展开更多
Cryosurgery is an effective way of curing many diseases including tumors and cancers. It can be applied using a variety of systems and cryogens. Cheap, convenient, reliable equipment still needs to be developed so tha...Cryosurgery is an effective way of curing many diseases including tumors and cancers. It can be applied using a variety of systems and cryogens. Cheap, convenient, reliable equipment still needs to be developed so that cryotherapy may be accepted by surgeons and hospitals. This paper presents a cryosurgery apparatus that utilizes an auto-cascade refrigeration system. Refrigerant mixture R50/R23/R600a was selected as the working fluid. The mixture composition was altered to achieve lower temperatures and higher capacity. The lowest temperature at the cryoprobe could be as low as -100℃, and 8 W refrigeration capacity could be obtained at -80 ℃. An ice ball of 11.6 mm diameter could be formed when the cryoprobe was immersed in a water bath at 37 ℃.展开更多
Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibite...Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibited excellent electrocatalytic activity for the oxygen reduction reaction. The electron transfer number was calculated to be -3.9 at -0.7 V （vs. Ag/AgCl） from the slope of the Koutecky-Levich plots. The U3O8/rGO hybrids were more stable than commercial Pt/C catalysts. Furthermore, when methanol was present, the U3O8/rGO hybrids still retained high activity. In addition, the UBO8/rGO hybrids can also catalyze the reduction of hydrogen peroxide.展开更多
Recent genomic studies have highlighted the importance of hybridization and gene exchange in evolution. We ask what factors cause variation in the impact of hybridization, through adaptation in hybrids and the likelih...Recent genomic studies have highlighted the importance of hybridization and gene exchange in evolution. We ask what factors cause variation in the impact of hybridization, through adaptation in hybrids and the likelihood of hybrid speciation. During speciation, traits that diverge due to both divergent and stabilizing selection can contribute to the buildup of reproductive isolation. Divergent directional selection in parent taxa should lead to intermediate phenotypes in hybrids, whereas stabilizing se- lection can also produce extreme, transgressive phenotypes when hybridization occurs. By examining existing theory and em- pirical data, we discuss how these effects, combined with differences between modes of divergence in the chromosomal distribu- tion of incompatibilities, affect adaptation and speciation in hybrid populations. The result is a clear and testable set of predic- tions that can be used to examine hybrid adaptation and speciation. Stabilizing selection in parents increases transgression in hy- brids, increasing the possibility for novel adaptation. Divergent directional selection causes intermediate hybrid phenotypes and increases their ability to evolve along the direction of parental differentiation. Stabilizing selection biases incompatibilities to- wards autosomes, leading to reduced sexual correlations in trait values and reduced pleiotropy in hybrids, and hence increased freedom in the direction of evolution. Directional selection causes a bias towards sex-linked incompatibilities, with the opposite consequences. Divergence by directional selection leads to greater dominance effects than stabilizing selection, with major but variable impacts on hybrid evolution [Current Zoology 59 （5）： 675-685, 2013].展开更多
文摘Genetic analysis of yield and yield components were carried out on three parental clones of Coffea canephora Pierre and their controlled hybrid progenies. There is a possibility to estimate coffee yield capabilities in simply via the easier measuring traits of yield components since significant correlation between them were detected. We found that among parental show very few significantly differences of all observed characters and even not found between the overall mean of the descendants and their donor parents, whereas some particular descendants show higher values rather than their donor parent in one or more characters. Increased value between the best parent to the best descendent were detected varies from zero to 102%. This situation suggests the difficulty to find out the optimum yield in a single plant by accumulating all of yield components that actually can increase 143% to 278% from actual to potential yields. In addition, observed characters among population were also actually found highly varies from 159% in out-turn in population B to 28,333% in number of productive branch among population A. Low heritability （h2） that generally found in quantitative traits due to polygenic control was present in our studies in almost all characters observed. Therefore, selection for actual high yielding through conventional breeding will not efficient, and more convincing the power of selection using molecular markers to assist for cumulate additive effects in a single genotypes that resulted of high yielding in the future.
基金Project (No.50606032) supported by the National Natural Science Foundation of China
文摘Cryosurgery is an effective way of curing many diseases including tumors and cancers. It can be applied using a variety of systems and cryogens. Cheap, convenient, reliable equipment still needs to be developed so that cryotherapy may be accepted by surgeons and hospitals. This paper presents a cryosurgery apparatus that utilizes an auto-cascade refrigeration system. Refrigerant mixture R50/R23/R600a was selected as the working fluid. The mixture composition was altered to achieve lower temperatures and higher capacity. The lowest temperature at the cryoprobe could be as low as -100℃, and 8 W refrigeration capacity could be obtained at -80 ℃. An ice ball of 11.6 mm diameter could be formed when the cryoprobe was immersed in a water bath at 37 ℃.
文摘Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibited excellent electrocatalytic activity for the oxygen reduction reaction. The electron transfer number was calculated to be -3.9 at -0.7 V （vs. Ag/AgCl） from the slope of the Koutecky-Levich plots. The U3O8/rGO hybrids were more stable than commercial Pt/C catalysts. Furthermore, when methanol was present, the U3O8/rGO hybrids still retained high activity. In addition, the UBO8/rGO hybrids can also catalyze the reduction of hydrogen peroxide.
文摘Recent genomic studies have highlighted the importance of hybridization and gene exchange in evolution. We ask what factors cause variation in the impact of hybridization, through adaptation in hybrids and the likelihood of hybrid speciation. During speciation, traits that diverge due to both divergent and stabilizing selection can contribute to the buildup of reproductive isolation. Divergent directional selection in parent taxa should lead to intermediate phenotypes in hybrids, whereas stabilizing se- lection can also produce extreme, transgressive phenotypes when hybridization occurs. By examining existing theory and em- pirical data, we discuss how these effects, combined with differences between modes of divergence in the chromosomal distribu- tion of incompatibilities, affect adaptation and speciation in hybrid populations. The result is a clear and testable set of predic- tions that can be used to examine hybrid adaptation and speciation. Stabilizing selection in parents increases transgression in hy- brids, increasing the possibility for novel adaptation. Divergent directional selection causes intermediate hybrid phenotypes and increases their ability to evolve along the direction of parental differentiation. Stabilizing selection biases incompatibilities to- wards autosomes, leading to reduced sexual correlations in trait values and reduced pleiotropy in hybrids, and hence increased freedom in the direction of evolution. Directional selection causes a bias towards sex-linked incompatibilities, with the opposite consequences. Divergence by directional selection leads to greater dominance effects than stabilizing selection, with major but variable impacts on hybrid evolution [Current Zoology 59 （5）： 675-685, 2013].
