Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various n...Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various non-proton nuclei(X-nuclei)MRI can provide more metabolic information.However,due to the relatively poor signal-to-noise ratio(SNR)of X-nuclei MRI,their applications are quite rare compared to^(1)H.Benefit from the rapid developments of MRI hardware and software technologies,X-nuclei MRI has recently attracted increasing interests in biomedical research.This review firstly introduces some current methods to improve the SNR of X-nuclei MRI.Secondly,this review describes biomedical applications of X-nuclei MRI,especially focusing on the current use of X-nuclei(^(13)C,^(17)O,^(19)F,^(23)Na and^(31)P)MRI to study related diseases in different organs,including the brain,liver,kidney,heart and bone.Finally,perspectives studies on X-nuclei imaging and its potential applications are described in biomedical research.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
目的比较Hestrin比色法(简称比色法)和核磁共振(nuclear magnetic resonance,NMR)法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖氧乙酰基(O-Acetyl,OAc)含量的相关性和精密度。方法用比色法和NMR法测定A、C、Y、W135群脑膜炎球菌荚膜多糖...目的比较Hestrin比色法(简称比色法)和核磁共振(nuclear magnetic resonance,NMR)法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖氧乙酰基(O-Acetyl,OAc)含量的相关性和精密度。方法用比色法和NMR法测定A、C、Y、W135群脑膜炎球菌荚膜多糖及其多糖衍生物,Y、W135群荚膜多糖水解物的OAc含量,比较分析两种方法的相关性及精密度。结果两种方法检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量的决定系数分别为R^2≥0.954、R^2≥0.960、R^2≥0.969、R^2≥0.972;比色法检测3批C群脑膜炎球菌荚膜多糖(PSC)OAc含量的精密度,SD值分别为0.21、0.21、0.18,对应CV值分别为9.03%、9.01%、8.70%(95%置信区间);NMR法检测3批A群脑膜炎球菌荚膜多糖(PSA)OAc含量的精密度,SD值分别为0.66、0.78、0.83,对应CV值分别为0.72%、0.85%、0.93%(95%置信区间);结论比色法和NMR法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量方面相关性良好,精密度良好,核磁法较比色法精密度更高。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
actoxy-19-nor-progesterone was synthesized by a new efficient stereoselective asymmertric pathway from 19-nor-androst-4-en-3,17-dione in 5-steps reactions with overall yield 63.3%. Consequently, a strategy was used to...actoxy-19-nor-progesterone was synthesized by a new efficient stereoselective asymmertric pathway from 19-nor-androst-4-en-3,17-dione in 5-steps reactions with overall yield 63.3%. Consequently, a strategy was used to produce of 17-α-hydroxyl compound stereoselectively by addition 17-keto steroid with hydrogen cyanide, at the same time, the conditions of this asymmertric reaction were optimized. The titled compound and the intermediate were fully characterized by 1H, one dimension and two dimension 13C-nuclear magnetic resonance, and infrared spectrum. The results show that the rate of 17-α-hydroxyl compound isomeride is sensitively affected by the solution system and the best volume ratio of CH3OH to H2O is 36%. After the carbonyl and hydroxyl groups were protected by ethylenediol and vinyl butyl ether respectively, organometallic addition to CN group with CH3Li, androstance compound was converted to pregnane compound. After removing the protective groups by a mild hydrolytic procedure with high yield, the titled compound was obtained by esterified the above intermidiate. The new pathway gives a good purity of 98% as determined by high performance liquid chromatography.展开更多
基金supported by Chinese Academy of Sciences MRI Technology Alliance under Grant 2020GZ1003.
文摘Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various non-proton nuclei(X-nuclei)MRI can provide more metabolic information.However,due to the relatively poor signal-to-noise ratio(SNR)of X-nuclei MRI,their applications are quite rare compared to^(1)H.Benefit from the rapid developments of MRI hardware and software technologies,X-nuclei MRI has recently attracted increasing interests in biomedical research.This review firstly introduces some current methods to improve the SNR of X-nuclei MRI.Secondly,this review describes biomedical applications of X-nuclei MRI,especially focusing on the current use of X-nuclei(^(13)C,^(17)O,^(19)F,^(23)Na and^(31)P)MRI to study related diseases in different organs,including the brain,liver,kidney,heart and bone.Finally,perspectives studies on X-nuclei imaging and its potential applications are described in biomedical research.
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。
文摘目的比较Hestrin比色法(简称比色法)和核磁共振(nuclear magnetic resonance,NMR)法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖氧乙酰基(O-Acetyl,OAc)含量的相关性和精密度。方法用比色法和NMR法测定A、C、Y、W135群脑膜炎球菌荚膜多糖及其多糖衍生物,Y、W135群荚膜多糖水解物的OAc含量,比较分析两种方法的相关性及精密度。结果两种方法检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量的决定系数分别为R^2≥0.954、R^2≥0.960、R^2≥0.969、R^2≥0.972;比色法检测3批C群脑膜炎球菌荚膜多糖(PSC)OAc含量的精密度,SD值分别为0.21、0.21、0.18,对应CV值分别为9.03%、9.01%、8.70%(95%置信区间);NMR法检测3批A群脑膜炎球菌荚膜多糖(PSA)OAc含量的精密度,SD值分别为0.66、0.78、0.83,对应CV值分别为0.72%、0.85%、0.93%(95%置信区间);结论比色法和NMR法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量方面相关性良好,精密度良好,核磁法较比色法精密度更高。
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.
文摘actoxy-19-nor-progesterone was synthesized by a new efficient stereoselective asymmertric pathway from 19-nor-androst-4-en-3,17-dione in 5-steps reactions with overall yield 63.3%. Consequently, a strategy was used to produce of 17-α-hydroxyl compound stereoselectively by addition 17-keto steroid with hydrogen cyanide, at the same time, the conditions of this asymmertric reaction were optimized. The titled compound and the intermediate were fully characterized by 1H, one dimension and two dimension 13C-nuclear magnetic resonance, and infrared spectrum. The results show that the rate of 17-α-hydroxyl compound isomeride is sensitively affected by the solution system and the best volume ratio of CH3OH to H2O is 36%. After the carbonyl and hydroxyl groups were protected by ethylenediol and vinyl butyl ether respectively, organometallic addition to CN group with CH3Li, androstance compound was converted to pregnane compound. After removing the protective groups by a mild hydrolytic procedure with high yield, the titled compound was obtained by esterified the above intermidiate. The new pathway gives a good purity of 98% as determined by high performance liquid chromatography.
