AIM: To discuss the advantages of ultra-high field (7T) for 1H and 13C magnetic resonance spectroscopy (MRS) studies of metabolism.METHODS: Measurements of brain metabolites were made at both 3 and 7T using 1H MRS. Me...AIM: To discuss the advantages of ultra-high field (7T) for 1H and 13C magnetic resonance spectroscopy (MRS) studies of metabolism.METHODS: Measurements of brain metabolites were made at both 3 and 7T using 1H MRS. Measurements of glycogen and lipids in muscle were measured using 13C and 1H MRS respectively.RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen (13C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) (1H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO2 max; -58% at 75% VO2 max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study.CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.展开更多
近年来,生物质碳(biochar)作为新型吸附剂被广泛研究。但由于制备biochar的生物质原料和热解温度的不同,使biochar的结构和组成存在差异,从而影响其对污染物的吸附。目前关于biochar的结构和组成的研究还不够全面。因此,结合了能谱与光...近年来,生物质碳(biochar)作为新型吸附剂被广泛研究。但由于制备biochar的生物质原料和热解温度的不同,使biochar的结构和组成存在差异,从而影响其对污染物的吸附。目前关于biochar的结构和组成的研究还不够全面。因此,结合了能谱与光谱分析的手段,对biochar的结构和组成进行了深入的分析。选取木质类(柳树枝条)和草类(水稻秸秆)作为原料,分别在不同热解温度(300,450和600℃)下制得biochars,并对biochars样品进行元素分析、X射线光电子能谱分析(XPS)和固态13 C核磁共振(13 C NMR)研究,以阐明不同热解温度和生物质来源的biochars的结构和组成。结果显示:biochar的H/C,O/C和(O+N)/C的比值随着热解温度的升高而降低;草类biochar比木质类biochar具有更高的灰分含量和表面极性;木质类biochar的矿物主要分布在样品颗粒内部,其表面被有机质覆盖,而草类biochar部分矿物暴露在样品颗粒表面;13 C NMR显示低温制得的biochar主要由芳香碳、脂肪碳、羧基和羰基碳组成,高温制得的biochar主要由芳香碳组成,且低温制得biochars中,木质类biochars比草类biochars含有更高的木质素的残留碳结构,这是由于木质类biochars原材料中含有更高的木质素。展开更多
为明确颗粒有机碳在土壤固碳中的作用机制,对比研究了不同有机培肥土壤颗粒有机碳的结构差异。以单施化肥处理为对照,选择了四种有机物料进行定位培肥试验,利用^(13) C NMR和红外光谱技术对比分析不同有机培肥对土壤颗粒有机碳结构的影...为明确颗粒有机碳在土壤固碳中的作用机制,对比研究了不同有机培肥土壤颗粒有机碳的结构差异。以单施化肥处理为对照,选择了四种有机物料进行定位培肥试验,利用^(13) C NMR和红外光谱技术对比分析不同有机培肥对土壤颗粒有机碳结构的影响。结果表明:颗粒有机碳以脂肪碳和含氧基团为主,脂化度高于75%,含氧官能团含量高于50%;不同有机培肥对土壤颗粒有机碳结构的影响差异性显著,树叶培肥在提高颗粒有机碳芳香度的同时,亲水性也大幅度提高,比单施化肥处理(对照)提高了0.78%;短期内,牛粪、秸秆和树叶培肥均可提高土壤颗粒有机碳的芳香度,但从长远角度分析,牛粪和秸秆培肥更利于土壤颗粒有机碳的稳定,尤其是秸秆培肥,其颗粒有机碳的芳香度分别比对照和牛粪培肥高0.35%和0.11%,而亲水性远低于二者;红外光谱与核磁分析的结果基本一致,红外光谱可用于大量样品的颗粒有机碳结构初步筛选。展开更多
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
A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemically equivalent carbon atoms in alcohols and alkanes. Combining AEDV and γ parameter, four...A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemically equivalent carbon atoms in alcohols and alkanes. Combining AEDV and γ parameter, four five-parameter linear relationship equations of chemical shift for four types of carbon atom are created by using multiple linear regression. Correlation coefficients are R = 0.9887, 0.9972, 0.9918 and 0.9968 end roots of mean square error are RMS = 0.906, 0. 821, 1.091 and 1.091 of four types of carbons, i.e., type 1, 2, 3, and 4 for primary, secondary, tertiary, and quaternary carbons, respectively. The stability and prediction capacity for external samples of four models have been tested by cross-validation.展开更多
Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existen...Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.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
基金Supported by The Haldane-Spearman Consortium for PhD funding for Dr. Gunner F, Swecarb AB for provision of the carbo-hydrate drink，and Pfizer for funding the 1H Repeatability work Dr.Stephenson M was supported by the University of Notting-ham’s Mansfield Fellowship scheme+2 种基金7T work was supported by grant G9900259 from the Medical Research CouncilPfizer and grant G0901321 from the Medical Research CouncilThe 7 T MR Scanner in Nottingham, was funded by a Joint Infrastructure Fund Grant from the Wellcome Trust UK
文摘AIM: To discuss the advantages of ultra-high field (7T) for 1H and 13C magnetic resonance spectroscopy (MRS) studies of metabolism.METHODS: Measurements of brain metabolites were made at both 3 and 7T using 1H MRS. Measurements of glycogen and lipids in muscle were measured using 13C and 1H MRS respectively.RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen (13C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) (1H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO2 max; -58% at 75% VO2 max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study.CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.
文摘近年来,生物质碳(biochar)作为新型吸附剂被广泛研究。但由于制备biochar的生物质原料和热解温度的不同,使biochar的结构和组成存在差异,从而影响其对污染物的吸附。目前关于biochar的结构和组成的研究还不够全面。因此,结合了能谱与光谱分析的手段,对biochar的结构和组成进行了深入的分析。选取木质类(柳树枝条)和草类(水稻秸秆)作为原料,分别在不同热解温度(300,450和600℃)下制得biochars,并对biochars样品进行元素分析、X射线光电子能谱分析(XPS)和固态13 C核磁共振(13 C NMR)研究,以阐明不同热解温度和生物质来源的biochars的结构和组成。结果显示:biochar的H/C,O/C和(O+N)/C的比值随着热解温度的升高而降低;草类biochar比木质类biochar具有更高的灰分含量和表面极性;木质类biochar的矿物主要分布在样品颗粒内部,其表面被有机质覆盖,而草类biochar部分矿物暴露在样品颗粒表面;13 C NMR显示低温制得的biochar主要由芳香碳、脂肪碳、羧基和羰基碳组成,高温制得的biochar主要由芳香碳组成,且低温制得biochars中,木质类biochars比草类biochars含有更高的木质素的残留碳结构,这是由于木质类biochars原材料中含有更高的木质素。
基金Jilin Province Science and Technology Department Major Technical Special Bidding Projects(20150203004NY)National Key R&D Projects(2017YFD0201801)
文摘为明确颗粒有机碳在土壤固碳中的作用机制,对比研究了不同有机培肥土壤颗粒有机碳的结构差异。以单施化肥处理为对照,选择了四种有机物料进行定位培肥试验,利用^(13) C NMR和红外光谱技术对比分析不同有机培肥对土壤颗粒有机碳结构的影响。结果表明:颗粒有机碳以脂肪碳和含氧基团为主,脂化度高于75%,含氧官能团含量高于50%;不同有机培肥对土壤颗粒有机碳结构的影响差异性显著,树叶培肥在提高颗粒有机碳芳香度的同时,亲水性也大幅度提高,比单施化肥处理(对照)提高了0.78%;短期内,牛粪、秸秆和树叶培肥均可提高土壤颗粒有机碳的芳香度,但从长远角度分析,牛粪和秸秆培肥更利于土壤颗粒有机碳的稳定,尤其是秸秆培肥,其颗粒有机碳的芳香度分别比对照和牛粪培肥高0.35%和0.11%,而亲水性远低于二者;红外光谱与核磁分析的结果基本一致,红外光谱可用于大量样品的颗粒有机碳结构初步筛选。
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Project supported by Ministry of Education "Chunhui Program" and Fok Ying Tung Education Foundation.
文摘A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemically equivalent carbon atoms in alcohols and alkanes. Combining AEDV and γ parameter, four five-parameter linear relationship equations of chemical shift for four types of carbon atom are created by using multiple linear regression. Correlation coefficients are R = 0.9887, 0.9972, 0.9918 and 0.9968 end roots of mean square error are RMS = 0.906, 0. 821, 1.091 and 1.091 of four types of carbons, i.e., type 1, 2, 3, and 4 for primary, secondary, tertiary, and quaternary carbons, respectively. The stability and prediction capacity for external samples of four models have been tested by cross-validation.
基金supported by the National Natural Science Foundation of China(41872174 and 42072189)the Program for Innovative Research Team(in Science and Technology)in the Universities of Henan Province,China(21IRTSTHN007)the Program for Innovative Research Team(in Science and Technology)of Henan Polytechnic University(T2020-4)。
文摘Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.
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.
