委内瑞拉岩沥青(Venezuelan rock asphalt,VRA)是一种批量开采时间不长的岩沥青,为探究不同掺量下VRA改性沥青的掺配性能及老化机理,针对VRA改性沥青,研究提出了VRA改性沥青的制备工艺,选取0%、4%、8%、12%、16%和20%共6种VRA掺量,开展...委内瑞拉岩沥青(Venezuelan rock asphalt,VRA)是一种批量开采时间不长的岩沥青,为探究不同掺量下VRA改性沥青的掺配性能及老化机理,针对VRA改性沥青,研究提出了VRA改性沥青的制备工艺,选取0%、4%、8%、12%、16%和20%共6种VRA掺量,开展旋转薄膜烘箱老化试验(rotating thin film oven test,RTFOT)老化前后的质量、三大指标、黏度、原子力显微镜(atomic force microscope,AFM)等测试,计算分析了质量损失、残留针入度比、软化点增量、延度变化、黏度比、老化指数、AFM二维图、AFM三维图、AFM图表面粗糙度等技术指标。研究表明:随VRA掺量增长,VRA改性沥青老化前后针入度呈指数下降、135℃旋转黏度呈指数上升、软化点呈线性上升、15℃延度急剧下降并趋于平稳、质量损失绝对值呈线性增加、粗糙度呈凹形抛物线变化。研究发现4%~8%VRA改性沥青老化前后技术性能较好,是一种优质的岩沥青改性沥青。展开更多
This study has examined the structure and function of the biliverdin reductase A (BLVRA) gene and its correlation with the green eggshell character in Jinyun ducks. The previously unknown sequences of 3' and 5'...This study has examined the structure and function of the biliverdin reductase A (BLVRA) gene and its correlation with the green eggshell character in Jinyun ducks. The previously unknown sequences of 3' and 5' ends of duck BLVRA mRNA were cloned, using RT-PCR and 5' RACE methods with four pairs of primers designed from the known coding sequence (CDS) of the duck BLVRA gene. Gene expression levels of BLVRA in the shell gland were quantified by real-time PCR, and eggshell colors were determined objectively by the reflection coefficient. The cDNA sequence of BLVRA was comprised of 1071 nucleotides, encoding a protein of 303 amino acids with an isoelectric point of 7.15 and molecular weight of 34.3 kDa. The 5' and 3' ends of the duck BLVRA gene sequence published in the GenBank were extended by 238 and 199 bp, respectively. The deduced amino acid sequence of duck BLVRA had 95.3% identity with Gallus gallus, 95.0% with Taeniopygia guttata, 70.0% with Xenopus tropicalis,61.1% with Bos taurus, 60.5% with Homo sapiens and 59.5% with Mus musculus, which indicated that the BLVRA gene was evolutionarily conserved. The relative gene expression level of BLVRA in shell glands of Jinyun ducks with white eggshells was 3 times higher than that in ducks with dark green eggshells (P<0.01). There was a significant positive correlation between reflection coefficient of eggshells and the relative expression of the BLVRA gene (r=0.719, P<0.05). Together, these findings suggest that the BLVRA gene could be a candidate gene for the molecule breeding of ducks with green eggshells.展开更多
文摘委内瑞拉岩沥青(Venezuelan rock asphalt,VRA)是一种批量开采时间不长的岩沥青,为探究不同掺量下VRA改性沥青的掺配性能及老化机理,针对VRA改性沥青,研究提出了VRA改性沥青的制备工艺,选取0%、4%、8%、12%、16%和20%共6种VRA掺量,开展旋转薄膜烘箱老化试验(rotating thin film oven test,RTFOT)老化前后的质量、三大指标、黏度、原子力显微镜(atomic force microscope,AFM)等测试,计算分析了质量损失、残留针入度比、软化点增量、延度变化、黏度比、老化指数、AFM二维图、AFM三维图、AFM图表面粗糙度等技术指标。研究表明:随VRA掺量增长,VRA改性沥青老化前后针入度呈指数下降、135℃旋转黏度呈指数上升、软化点呈线性上升、15℃延度急剧下降并趋于平稳、质量损失绝对值呈线性增加、粗糙度呈凹形抛物线变化。研究发现4%~8%VRA改性沥青老化前后技术性能较好,是一种优质的岩沥青改性沥青。
文摘This study has examined the structure and function of the biliverdin reductase A (BLVRA) gene and its correlation with the green eggshell character in Jinyun ducks. The previously unknown sequences of 3' and 5' ends of duck BLVRA mRNA were cloned, using RT-PCR and 5' RACE methods with four pairs of primers designed from the known coding sequence (CDS) of the duck BLVRA gene. Gene expression levels of BLVRA in the shell gland were quantified by real-time PCR, and eggshell colors were determined objectively by the reflection coefficient. The cDNA sequence of BLVRA was comprised of 1071 nucleotides, encoding a protein of 303 amino acids with an isoelectric point of 7.15 and molecular weight of 34.3 kDa. The 5' and 3' ends of the duck BLVRA gene sequence published in the GenBank were extended by 238 and 199 bp, respectively. The deduced amino acid sequence of duck BLVRA had 95.3% identity with Gallus gallus, 95.0% with Taeniopygia guttata, 70.0% with Xenopus tropicalis,61.1% with Bos taurus, 60.5% with Homo sapiens and 59.5% with Mus musculus, which indicated that the BLVRA gene was evolutionarily conserved. The relative gene expression level of BLVRA in shell glands of Jinyun ducks with white eggshells was 3 times higher than that in ducks with dark green eggshells (P<0.01). There was a significant positive correlation between reflection coefficient of eggshells and the relative expression of the BLVRA gene (r=0.719, P<0.05). Together, these findings suggest that the BLVRA gene could be a candidate gene for the molecule breeding of ducks with green eggshells.
