Ultra-long n-alkanes are highly valuable in both scientific research and as major constituents of specialty high-melting-point waxes.Unlike conventional methods(e.g.,Fischer–Tropsch(FT),ethylene oligomerization,and p...Ultra-long n-alkanes are highly valuable in both scientific research and as major constituents of specialty high-melting-point waxes.Unlike conventional methods(e.g.,Fischer–Tropsch(FT),ethylene oligomerization,and polyethylene cracking)typically resulting in wide n-alkane distributions,the elaborate design strategy presented herein allows the direct synthesis of pure,long n-alkanes using a modular splicing method with acetone,furfural,and fatty acid anhydrides or acyl chlorides as bio-blocks.The herein approach is based on a simple four-step catalytic reaction scheme involving C–C chain elongation and C–O bond activation.The synthesized pure n-alkanes had a carbon chain length as high as C_(49)(total yield of 49%).The synthesis approach also allows to selectively prepare n-alkanes with even and odd carbon numbers ranging from C15 to C_(49).This process represents a great breakthrough in the synthesis of long-chain pure n-alkanes,surpassing the carbon number limitations reported in previous methodologies.展开更多
The records of high-resolution terrestrial biological markers （biomarkers） from Core B2-9 from the northern Bering Sea Slope over the last 9.6 ka BP were presented in the study. Variations in input of terrestrial lo...The records of high-resolution terrestrial biological markers （biomarkers） from Core B2-9 from the northern Bering Sea Slope over the last 9.6 ka BP were presented in the study. Variations in input of terrestrial long-chain n-alkanes （referred to as n-alkanes） and vegetation structure in their source regions were investigated. The results show that the nCz7 is the main carbon peak and has the greatest contribution rate of the total n-alkane content; this might be related to the abundance of woody plants and their spatial distribution in the source region, nC23 is another n-alkane having a relatively high content; this was mainly derived from submerged plants widespread along the coastal areas in the northern hemisphere. Total n-alkane content dropped quickly at ca. 7.8 ka BP, ca. 6.7 ka BP and ca. 5.4 ka BP, and was followed by four relatively stable stages mostly controlled by sea-level rise, climate change and vegetation distribution in the source region. Variation in carbon preference index （CPI） indicates that the n-alkanes primarily originated from higher land plants, and the average chain length （ACL） and nCa1/nC27 ratio reveal the relatively stable presence of woody/herbaceous plants during the Holocene, and dominate woody plants in most of the time. Simultaneous variation in total n-alkane content, nC27 content and its contribution, CPI, ACL and nC31/nC27 ratio over several short periods suggest that the growth rate of the woody plant n-alkane contribution was lower than that of herbaceous plants and fossil n-alkanes under the particular climatic conditions of the source region.展开更多
Aligned carbon nanotubes(CNTs)were synthesized by nebulized spray pyrolysis of solutions of organometallics in carbon precursor solvents.Four types of straight-chained alkanes including n-pentane,n-hexane,n-heptane an...Aligned carbon nanotubes(CNTs)were synthesized by nebulized spray pyrolysis of solutions of organometallics in carbon precursor solvents.Four types of straight-chained alkanes including n-pentane,n-hexane,n-heptane and n-octane were used as precursor solvents for synthesis of aligned CNTs.The results from scanning electron microscopy,transmission electron microscopy and Raman spectroscopy show that the CNTs obtained from them have different diameters and degrees of graphitization. It is found that the n-heptane is the most suitable for the growth of aligned CNTs with high quality and yield.The thermodynamic properties of precursory carbon sources such as boiling point and formation enthalpy are considered to play a decisive role in the synthesis of CNTs.It will be very helpful for the controllable preparation of aligned CNTs at relatively low cost.展开更多
To characterize the long-chain cyclic alkane (c-alkane) degradation of bacteria in Rhodococcus, we analyzed the relationship between the alkane hydroxylase gene (alkB) and long-chain c-alkane degradation in 19 species...To characterize the long-chain cyclic alkane (c-alkane) degradation of bacteria in Rhodococcus, we analyzed the relationship between the alkane hydroxylase gene (alkB) and long-chain c-alkane degradation in 19 species. Eleven strains which were isolated from nature using long-chain c-alkane as a substrate were identified as R. erythropolisc, and all were shown to carry the alkB [alkB R2 type]. This gene type was also carried by two other species, R. rhodochrous and R. baikonurensis. In total, 17 species of the genus Rhodococcus carried alkB, but the gene types differed from each other. The two species R. rhodnii and R. coprophilus did not carry alkB, and their long-chain c-alkane degradation levels were low.展开更多
The molecular distribution of long-chain n-alkanes in 62 soil samples collected from diverse locations across eastern China was analyzed.The long-chain n-alkanes were mostly dominated by n-C29 or n-C31,regardless of t...The molecular distribution of long-chain n-alkanes in 62 soil samples collected from diverse locations across eastern China was analyzed.The long-chain n-alkanes were mostly dominated by n-C29 or n-C31,regardless of the overlying vegetation type at each site.The results were compared with those summarized from the literature,covering more than 100 soil samples within China and more than 300 genera of modern plants distributed worldwide.There were similar n-alkane distribution patterns for most genera, with no clear differences among grasses,shrubs,and trees.The evidence from analyses of surface soils and modern plants indicates that the relationship between the molecular distribution of long-chain n-alkanes of surface soils and source vegetation is highly complex,and is influenced by many factors.Further,it is suggested that source vegetation types should not be simply inferred from distribution patterns of long-chain n-alkanes in sediments.展开更多
基金supported by National Natural Science Foundation of China(General Program,No.22372060)Shanghai Municipal Science and Technology Commission Project(No.22dz1209300)National Natural Science Youth Fund(No.22205065)。
文摘Ultra-long n-alkanes are highly valuable in both scientific research and as major constituents of specialty high-melting-point waxes.Unlike conventional methods(e.g.,Fischer–Tropsch(FT),ethylene oligomerization,and polyethylene cracking)typically resulting in wide n-alkane distributions,the elaborate design strategy presented herein allows the direct synthesis of pure,long n-alkanes using a modular splicing method with acetone,furfural,and fatty acid anhydrides or acyl chlorides as bio-blocks.The herein approach is based on a simple four-step catalytic reaction scheme involving C–C chain elongation and C–O bond activation.The synthesized pure n-alkanes had a carbon chain length as high as C_(49)(total yield of 49%).The synthesis approach also allows to selectively prepare n-alkanes with even and odd carbon numbers ranging from C15 to C_(49).This process represents a great breakthrough in the synthesis of long-chain pure n-alkanes,surpassing the carbon number limitations reported in previous methodologies.
基金The National Natural Science Foundation of China under contract Nos 41030859,41506223,CHINARE2017-03-02 and IC201105the Geological Investigation Project of China Geological Survey under contract Nos 12120113006200 and 1212011120044
文摘The records of high-resolution terrestrial biological markers （biomarkers） from Core B2-9 from the northern Bering Sea Slope over the last 9.6 ka BP were presented in the study. Variations in input of terrestrial long-chain n-alkanes （referred to as n-alkanes） and vegetation structure in their source regions were investigated. The results show that the nCz7 is the main carbon peak and has the greatest contribution rate of the total n-alkane content; this might be related to the abundance of woody plants and their spatial distribution in the source region, nC23 is another n-alkane having a relatively high content; this was mainly derived from submerged plants widespread along the coastal areas in the northern hemisphere. Total n-alkane content dropped quickly at ca. 7.8 ka BP, ca. 6.7 ka BP and ca. 5.4 ka BP, and was followed by four relatively stable stages mostly controlled by sea-level rise, climate change and vegetation distribution in the source region. Variation in carbon preference index （CPI） indicates that the n-alkanes primarily originated from higher land plants, and the average chain length （ACL） and nCa1/nC27 ratio reveal the relatively stable presence of woody/herbaceous plants during the Holocene, and dominate woody plants in most of the time. Simultaneous variation in total n-alkane content, nC27 content and its contribution, CPI, ACL and nC31/nC27 ratio over several short periods suggest that the growth rate of the woody plant n-alkane contribution was lower than that of herbaceous plants and fossil n-alkanes under the particular climatic conditions of the source region.
基金Projects(50772033, 50972043) supported by the National Natural Science Foundation of ChinaProject(2007FJ3003) supported by the Natural Science Foundation of Hunan Province, China
文摘Aligned carbon nanotubes(CNTs)were synthesized by nebulized spray pyrolysis of solutions of organometallics in carbon precursor solvents.Four types of straight-chained alkanes including n-pentane,n-hexane,n-heptane and n-octane were used as precursor solvents for synthesis of aligned CNTs.The results from scanning electron microscopy,transmission electron microscopy and Raman spectroscopy show that the CNTs obtained from them have different diameters and degrees of graphitization. It is found that the n-heptane is the most suitable for the growth of aligned CNTs with high quality and yield.The thermodynamic properties of precursory carbon sources such as boiling point and formation enthalpy are considered to play a decisive role in the synthesis of CNTs.It will be very helpful for the controllable preparation of aligned CNTs at relatively low cost.
文摘To characterize the long-chain cyclic alkane (c-alkane) degradation of bacteria in Rhodococcus, we analyzed the relationship between the alkane hydroxylase gene (alkB) and long-chain c-alkane degradation in 19 species. Eleven strains which were isolated from nature using long-chain c-alkane as a substrate were identified as R. erythropolisc, and all were shown to carry the alkB [alkB R2 type]. This gene type was also carried by two other species, R. rhodochrous and R. baikonurensis. In total, 17 species of the genus Rhodococcus carried alkB, but the gene types differed from each other. The two species R. rhodnii and R. coprophilus did not carry alkB, and their long-chain c-alkane degradation levels were low.
基金supported by the National Natural Science Foundation of China (40901055)the Key Project of the Chinese Ministry of Education (109151)+2 种基金the Fund for Creative Research Groups (41021091)the Cross-discipline Innovative Study Fund for Youth Talent of Lanzhou University (LZUJC2007011)the National Basic Research Program of China (2010CB950202 and 2010CB833405)
文摘The molecular distribution of long-chain n-alkanes in 62 soil samples collected from diverse locations across eastern China was analyzed.The long-chain n-alkanes were mostly dominated by n-C29 or n-C31,regardless of the overlying vegetation type at each site.The results were compared with those summarized from the literature,covering more than 100 soil samples within China and more than 300 genera of modern plants distributed worldwide.There were similar n-alkane distribution patterns for most genera, with no clear differences among grasses,shrubs,and trees.The evidence from analyses of surface soils and modern plants indicates that the relationship between the molecular distribution of long-chain n-alkanes of surface soils and source vegetation is highly complex,and is influenced by many factors.Further,it is suggested that source vegetation types should not be simply inferred from distribution patterns of long-chain n-alkanes in sediments.
