A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear reg...A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.展开更多
Forest soil carbon （C） is an important compo- nent of the global C cycle. However, the mechanism by which tree species influence soil organic C （SOC） pool composition and mineralization is poorly understood. To un...Forest soil carbon （C） is an important compo- nent of the global C cycle. However, the mechanism by which tree species influence soil organic C （SOC） pool composition and mineralization is poorly understood. To understand the effect of tree species on soil C cycling, we assessed total, labile, and recalcitrant SOC pools, SOC chemical composition by 13C nuclear magnetic resonance spectroscopy, and SOC mineralization in four monoculture plantations. Labile and recalcitrant SOC pools in surface （0-10 cm） and deep （40-60 cm） soils in the four forests contained similar content. In contrast, these SOC pools exhibited differences in the subsurface soil （from 10 to 20 cm and from 20 to 40 cm）. The alkyl C and O-alkyl C intensities of SOC were higher in Schima superba and Michelia macclurei forests than in Cunninghamia lanceolata and Pinus massoniana forests. In surface soil, S. superba and M. macclurei forests exhibited higher SOC mineralization rates than did P. massoniana and C.lanceolata forests. The slope of the straight line between C60 and labile SOC was steeper than that between C60 and total SOC. Our results suggest that roots affected the composition of SOC pools. Labile SOC pools also affected SOC mineralization to a greater extent than total SOC pools.展开更多
Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal t...Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal treatment of Inner Mongolia lignite(IM)was carried out in a lab autoclave.The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy,and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy.The curve-fitting method was used to calculate the content of the functional groups quantitatively.The results show that hydrothermal treatment is an effective method for upgrading the lignite.The side chains of the aromatic ring in lignite are altered,while the main macromolecular structure remains nearly the same.The hydrothermal treatment of IM could be divided into three temperature-dependent stages.The first stage(<493 K)is the decomposition reaction of oxygen functional groups,where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K.In the second stage(493–533 K),hydrolysis of functional groups and hydrogen transfer between water and lignite occur.Here,the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533,and the content of quinone generates from the condensation of free phenol increased.The third stage(>533 K)involves breakage of the covalent bond,and the content of CH4 and CO in the emission gas clearly increase.展开更多
概述了核磁共振(nuclear magnetic resonance,NMR)技术的发展简史、基本原理及在植物研究中的应用。主要从核磁共振磷谱在植物磷分级、细胞p H值和木素结构研究中的应用,核磁共振氢谱在植物结构鉴定和代谢研究中的应用及碳谱在植物木素...概述了核磁共振(nuclear magnetic resonance,NMR)技术的发展简史、基本原理及在植物研究中的应用。主要从核磁共振磷谱在植物磷分级、细胞p H值和木素结构研究中的应用,核磁共振氢谱在植物结构鉴定和代谢研究中的应用及碳谱在植物木素结构、化学结构研究中的应用3个方面进行论述,探讨研究中存在的主要问题并提出研究展望,为今后的进一步研究提供参考。展开更多
The humic acid（HA） sample obtained from the alluvial soil was characterized by elemental composition, pyrolysis gas chromatography-mass spectrometry（Py-GC-MS） and solid-state 13C nuclear magnetic resonance （13C ...The humic acid（HA） sample obtained from the alluvial soil was characterized by elemental composition, pyrolysis gas chromatography-mass spectrometry（Py-GC-MS） and solid-state 13C nuclear magnetic resonance （13C NMR） spectroscopy. There is high fat content and a few nitrogen-containing functional groups in HA. Py-GC-MS demonstrates the characterization and structural identification of HA. One long list of identified pyrolysis products was proposed for the construction of conceptual model of HA. Solid-state 13C NMR data indicate there are higher values of alkyl-C, O-alkyl-C and aryl-C in HA. The elemental composition, structural carbon distribution and L3C NMR spectroscopy of simulated HA are consistent with those of experimental HA. HyperChem was used to simulate the three-dimensional molecular structure of the monomer, which was optimized by the molecular mechanics of the optimized potential for liquid simulations（OPLS） force field and molecular dynamics simulation to get the stable and balanced conformation. The deprotonation process study depicts that the degree of ionization of HA gets deeper, while the electronegativity of HA and the energy of van der Waals（vdW） increase. Moreover, the 3D structure of humic acid with -4 charges is the most stable. The deprotonation process is an endothermic process.展开更多
Enteromorpha polysaccharide （Ep） extracted from alga a novel green coagulant aid for nanoparticles （NPs） and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration ...Enteromorpha polysaccharide （Ep） extracted from alga a novel green coagulant aid for nanoparticles （NPs） and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride （PAC-Ep） coagulants exhibited higher coagulation performance than that of the polyaluminum chloride （PAC） because of the negatively charged NPs suspension and humic aid （HA） solution. Significant high removal efficiencies of dissolved organic matter （94.1%）, turbidity （99.3%） and Zn ions （69.3%） were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including （i） AI^3＋ charge neutralization; （ii） hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; （iii） adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.展开更多
基金Projects(20775010, 21075011) supported by the National Natural Science Foundation of ChinaProject(2008AA05Z405) supported by the National High-tech Research and Development Program of China+2 种基金Project(09JJ3016) supported by the Natural Science Foundation of Hunan Province, ChinaProject(09C066) supported by the Scientific Research Fund of Hunan Provincial Education Department, ChinaProject(2010CL01) supported by the Foundation of Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, China
文摘A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.
基金supported by the National Natural Science Foundation of China(Grant No.31570466)the National Basic Research Program of China(Grant no.2012CB416905)
文摘Forest soil carbon （C） is an important compo- nent of the global C cycle. However, the mechanism by which tree species influence soil organic C （SOC） pool composition and mineralization is poorly understood. To understand the effect of tree species on soil C cycling, we assessed total, labile, and recalcitrant SOC pools, SOC chemical composition by 13C nuclear magnetic resonance spectroscopy, and SOC mineralization in four monoculture plantations. Labile and recalcitrant SOC pools in surface （0-10 cm） and deep （40-60 cm） soils in the four forests contained similar content. In contrast, these SOC pools exhibited differences in the subsurface soil （from 10 to 20 cm and from 20 to 40 cm）. The alkyl C and O-alkyl C intensities of SOC were higher in Schima superba and Michelia macclurei forests than in Cunninghamia lanceolata and Pinus massoniana forests. In surface soil, S. superba and M. macclurei forests exhibited higher SOC mineralization rates than did P. massoniana and C.lanceolata forests. The slope of the straight line between C60 and labile SOC was steeper than that between C60 and total SOC. Our results suggest that roots affected the composition of SOC pools. Labile SOC pools also affected SOC mineralization to a greater extent than total SOC pools.
基金This study was funded by National Key Basic Research Development Program of China(973Program,No.2011CB201304)Natural Science Foundation of China(51906021 and 51703014)+5 种基金National Key R&D Program of China(2018YFC1901203)Research Foundation for Advanced Talents of Jiangsu University(16JDG022)Changzhou University(ZMF17020034)Natural Science Foundation of Colleges in Jiangsu Province(19KJB480005)Changzhou Applied Basic Research Plan(CJ20190081)Science and Technology Project of Guangdong Province,PR China(No.2016A010105017)and(No.2017B040404009).
文摘Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis,liquefaction,and gasification processes.Here,hydrothermal treatment of Inner Mongolia lignite(IM)was carried out in a lab autoclave.The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy,and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy.The curve-fitting method was used to calculate the content of the functional groups quantitatively.The results show that hydrothermal treatment is an effective method for upgrading the lignite.The side chains of the aromatic ring in lignite are altered,while the main macromolecular structure remains nearly the same.The hydrothermal treatment of IM could be divided into three temperature-dependent stages.The first stage(<493 K)is the decomposition reaction of oxygen functional groups,where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K.In the second stage(493–533 K),hydrolysis of functional groups and hydrogen transfer between water and lignite occur.Here,the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533,and the content of quinone generates from the condensation of free phenol increased.The third stage(>533 K)involves breakage of the covalent bond,and the content of CH4 and CO in the emission gas clearly increase.
文摘概述了核磁共振(nuclear magnetic resonance,NMR)技术的发展简史、基本原理及在植物研究中的应用。主要从核磁共振磷谱在植物磷分级、细胞p H值和木素结构研究中的应用,核磁共振氢谱在植物结构鉴定和代谢研究中的应用及碳谱在植物木素结构、化学结构研究中的应用3个方面进行论述,探讨研究中存在的主要问题并提出研究展望,为今后的进一步研究提供参考。
基金the National Natural Science Foundation of China
文摘The humic acid（HA） sample obtained from the alluvial soil was characterized by elemental composition, pyrolysis gas chromatography-mass spectrometry（Py-GC-MS） and solid-state 13C nuclear magnetic resonance （13C NMR） spectroscopy. There is high fat content and a few nitrogen-containing functional groups in HA. Py-GC-MS demonstrates the characterization and structural identification of HA. One long list of identified pyrolysis products was proposed for the construction of conceptual model of HA. Solid-state 13C NMR data indicate there are higher values of alkyl-C, O-alkyl-C and aryl-C in HA. The elemental composition, structural carbon distribution and L3C NMR spectroscopy of simulated HA are consistent with those of experimental HA. HyperChem was used to simulate the three-dimensional molecular structure of the monomer, which was optimized by the molecular mechanics of the optimized potential for liquid simulations（OPLS） force field and molecular dynamics simulation to get the stable and balanced conformation. The deprotonation process study depicts that the degree of ionization of HA gets deeper, while the electronegativity of HA and the energy of van der Waals（vdW） increase. Moreover, the 3D structure of humic acid with -4 charges is the most stable. The deprotonation process is an endothermic process.
文摘Enteromorpha polysaccharide （Ep） extracted from alga a novel green coagulant aid for nanoparticles （NPs） and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride （PAC-Ep） coagulants exhibited higher coagulation performance than that of the polyaluminum chloride （PAC） because of the negatively charged NPs suspension and humic aid （HA） solution. Significant high removal efficiencies of dissolved organic matter （94.1%）, turbidity （99.3%） and Zn ions （69.3%） were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including （i） AI^3＋ charge neutralization; （ii） hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; （iii） adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.
