随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整...随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整来生产,通过CO_(2)加氢制备芳烃可以有效减缓对化石能源的过度依赖。但是CO_(2)的惰性强、活化能垒高、C–C偶联精准调控难,使低温CO_(2)加氢制备芳烃的高效催化剂开发存在巨大挑战。目前,采用氧化物–分子筛复合催化剂体系可以将CO_(2)加氢合成甲醇与甲醇制芳烃反应进行耦合,实现CO_(2)加氢直接合成芳烃。本文通过共沉淀法制备了ZnZrO_(x)复合氧化物,并采用等体积浸渍法引入不同过渡金属(Fe、Cu、Co、Ni),随后将其与商用ZSM-5分子筛物理混合制备了M-ZnZrO_(x)/ZSM-5复合催化剂。在275℃、H_(2)/CO_(2)=3、空速为600 m L/(g·h)的反应条件下,采用质量分数为4%的Fe改性的Fe-ZnZrO_(x)与ZSM-5组成的复合催化剂,芳烃选择性高达80.4%,CO_(2)转化率为5.6%,CO选择性为42.2%。进一步探究了ZnZrO_(x)氧化物上Fe含量对复合催化剂性能的影响,发现Fe含量增加有助于提升反应活性与芳烃选择性;当Fe负载量为8%时,芳烃选择性提升至85.0%。这一研究为在温和条件下通过CO_(2)加氢制备芳烃工业催化剂的开发提供了新思路。展开更多
风是近地层大气的主要物理量,也是影响林火蔓延的重要因素。本文以2020年“3·30”西昌森林火灾周围的近地面风场为研究对象,基于中尺度数值模式(Weather Research and Forecasting,WRF),采用6种边界层方案进行敏感性实验。结果表明...风是近地层大气的主要物理量,也是影响林火蔓延的重要因素。本文以2020年“3·30”西昌森林火灾周围的近地面风场为研究对象,基于中尺度数值模式(Weather Research and Forecasting,WRF),采用6种边界层方案进行敏感性实验。结果表明,YSU和Shin-Hong方案对凉山10 m风速模拟误差最小,YSU和MYNN3方案对凉山10 m风向模拟误差最小;YSU和Shin-Hong方案能模拟出西昌火灾区风场分布以及风向转变;在西昌站点YSU方案模拟的边界层结构最接近观测值,能较好地表现边界层内动力和热力结构。展开更多
Chinese chestnut is an important economic forest tree species with enormous application value in the wood,medical,and chemical industries.Currently,the limited genome-wide SSR molecular marker information on chestnut ...Chinese chestnut is an important economic forest tree species with enormous application value in the wood,medical,and chemical industries.Currently,the limited genome-wide SSR molecular marker information on chestnut resources significantly restricts research on the genetic diversity and identification of chestnut resources.To address this issue,we used GMATA to screen simple sequence repeat(SSR)markers throughout the Chinese chestnut genome.A total of 312,302 molecular markers were obtained with a density of 434.38 Mb-1.Subsequently,all SSR markers were examined for polymorphism using the Hip STR program and 138,208 polymorphic loci were ultimately obtained.To verify the capability of the developed SSR for identification,we randomly selected 36 markers on 12 chromosomes to construct fingerprint maps of 96 ancient Chinese chestnut resources from the Yanshan Mountains.The results showed that only six pairs of primers were required to create a unique DNA fingerprint of the tested ancient trees,showing that the developed markers have good potential for identification.We then evaluated the inter-specific universality and polymorphism of these markers using 91 Castanea plants of three different species.The molecular markers amplified 94%of the interspecies with a polymorphic information content(PIC)value of 0.859.Cluster analysis revealed that the resources can be well differentiated using these developed markers,and these markers can be widely used to identify interspecific boundaries.The results of this study proved that the developed molecular markers have the potential for assessing genotypic diversity,which can provide references for genetic diversity research,variety identification,kinship analysis,the selection of good products,and the construction of core germplasm resources of chestnut and even chestnut plants.Also these markers provide a solid foundation for the molecular design of hybrids,improved breeding and development of germplasm resources.展开更多
文摘随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整来生产,通过CO_(2)加氢制备芳烃可以有效减缓对化石能源的过度依赖。但是CO_(2)的惰性强、活化能垒高、C–C偶联精准调控难,使低温CO_(2)加氢制备芳烃的高效催化剂开发存在巨大挑战。目前,采用氧化物–分子筛复合催化剂体系可以将CO_(2)加氢合成甲醇与甲醇制芳烃反应进行耦合,实现CO_(2)加氢直接合成芳烃。本文通过共沉淀法制备了ZnZrO_(x)复合氧化物,并采用等体积浸渍法引入不同过渡金属(Fe、Cu、Co、Ni),随后将其与商用ZSM-5分子筛物理混合制备了M-ZnZrO_(x)/ZSM-5复合催化剂。在275℃、H_(2)/CO_(2)=3、空速为600 m L/(g·h)的反应条件下,采用质量分数为4%的Fe改性的Fe-ZnZrO_(x)与ZSM-5组成的复合催化剂,芳烃选择性高达80.4%,CO_(2)转化率为5.6%,CO选择性为42.2%。进一步探究了ZnZrO_(x)氧化物上Fe含量对复合催化剂性能的影响,发现Fe含量增加有助于提升反应活性与芳烃选择性;当Fe负载量为8%时,芳烃选择性提升至85.0%。这一研究为在温和条件下通过CO_(2)加氢制备芳烃工业催化剂的开发提供了新思路。
文摘风是近地层大气的主要物理量,也是影响林火蔓延的重要因素。本文以2020年“3·30”西昌森林火灾周围的近地面风场为研究对象,基于中尺度数值模式(Weather Research and Forecasting,WRF),采用6种边界层方案进行敏感性实验。结果表明,YSU和Shin-Hong方案对凉山10 m风速模拟误差最小,YSU和MYNN3方案对凉山10 m风向模拟误差最小;YSU和Shin-Hong方案能模拟出西昌火灾区风场分布以及风向转变;在西昌站点YSU方案模拟的边界层结构最接近观测值,能较好地表现边界层内动力和热力结构。
基金supported by the National Key Research&Development Program of China(2024YFD2200602)the National Natural Science Foundation of China(32471917)。
文摘Chinese chestnut is an important economic forest tree species with enormous application value in the wood,medical,and chemical industries.Currently,the limited genome-wide SSR molecular marker information on chestnut resources significantly restricts research on the genetic diversity and identification of chestnut resources.To address this issue,we used GMATA to screen simple sequence repeat(SSR)markers throughout the Chinese chestnut genome.A total of 312,302 molecular markers were obtained with a density of 434.38 Mb-1.Subsequently,all SSR markers were examined for polymorphism using the Hip STR program and 138,208 polymorphic loci were ultimately obtained.To verify the capability of the developed SSR for identification,we randomly selected 36 markers on 12 chromosomes to construct fingerprint maps of 96 ancient Chinese chestnut resources from the Yanshan Mountains.The results showed that only six pairs of primers were required to create a unique DNA fingerprint of the tested ancient trees,showing that the developed markers have good potential for identification.We then evaluated the inter-specific universality and polymorphism of these markers using 91 Castanea plants of three different species.The molecular markers amplified 94%of the interspecies with a polymorphic information content(PIC)value of 0.859.Cluster analysis revealed that the resources can be well differentiated using these developed markers,and these markers can be widely used to identify interspecific boundaries.The results of this study proved that the developed molecular markers have the potential for assessing genotypic diversity,which can provide references for genetic diversity research,variety identification,kinship analysis,the selection of good products,and the construction of core germplasm resources of chestnut and even chestnut plants.Also these markers provide a solid foundation for the molecular design of hybrids,improved breeding and development of germplasm resources.
