Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the cas...Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.展开更多
Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization...Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment （ACE-Asia）. The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317μg m^-3 and 307μg m^-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095μg m^-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196μg m^-3 on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite （K/C） ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.展开更多
In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrody...In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrodynamic corrections. In combination with high-precision measurements, it is feasible to precisely determine a molecular-based value of the proton- to-electron mass ratio. An experimental scheme is presented for measuring the rovibrational transition frequency （v,L） ： （0, 0） → （6,1） in HD＋, which is currently underway at the Wuhan Institute of Physics and Mathematics.展开更多
目的探讨法医毒物分析中液相色谱-串联质谱(liquid chromatography-tandem mass spectrome⁃try,LC-MS/MS)法检测血液中毒品类(甲基苯丙胺、吗啡、氯胺酮)、苯二氮蓝卓类(艾司唑仑、咪达唑仑、地西泮、氯硝西泮)和巴比妥类(苯巴比妥)共3...目的探讨法医毒物分析中液相色谱-串联质谱(liquid chromatography-tandem mass spectrome⁃try,LC-MS/MS)法检测血液中毒品类(甲基苯丙胺、吗啡、氯胺酮)、苯二氮蓝卓类(艾司唑仑、咪达唑仑、地西泮、氯硝西泮)和巴比妥类(苯巴比妥)共3大类8种常见药(毒)物的保留时间和离子丰度比的最大允许偏差。方法在2根色谱柱、3种色谱条件下,经液液萃取后采用LC-MS/MS进行检测,分析质量浓度在检出限(limit of detection,LOD)、2倍检出限(2LOD)、定量限(limit of quantitation,LOQ)、1.5倍定量限(1.5LOQ)、2倍定量限(2LOQ)、4倍定量限(4LOQ)和6倍定量限(6LOQ)共7个较低质量浓度时保留时间和离子丰度比的偏差。结果血液添加样品中8种药(毒)物绝对保留时间的偏差在±0.05 min范围内的占98.11%,相对保留时间的偏差在±0.4%范围内的占96.21%。离子丰度比的最大偏差与质量浓度存在高度关联:药(毒)物质量浓度为LOQ及以上时,离子丰度比的绝对偏差和相对偏差都有95%以上分别在±25%和±40%范围内;质量浓度为LOQ以下时,范围可分别扩大至±35%和±50%。结论建议8种常见药(毒)物绝对保留时间的偏差判定范围为±0.1min,相对保留时间的偏差判定范围为±1.0%。质量浓度在LOQ及以上时离子丰度比的绝对偏差判定范围为±25%,相对偏差为±40%,质量浓度在LOQ以下时偏差判定范围可分别扩大至±35%和±50%。展开更多
文摘Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.
基金The authors are very grateful to the anonymous reviewers for their constructive suggestions and comments.This research was supported by the National Natural Science Foundation of China(Grant No.40405023)the Chinese National Key Project of Basic Research(Grant G2004CB720200)+1 种基金the Science Foundation of Xi'an Jiaotong University(Grant No.XJJ2004006)a grant from the State Key Laboratory of Loess and Quaternary Geology(SKLLQG),Chinese Academy of Sciences.
文摘Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment （ACE-Asia）. The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317μg m^-3 and 307μg m^-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095μg m^-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196μg m^-3 on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite （K/C） ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.
基金supported by the National Natural Science Foundation of China(Grants Nos.11474316,11004221,10974224,and 11274348)the"Hundred Talent Program"of Chinese Academy of Sciences+1 种基金supported by NSERC,SHARCnet,ACEnet of Canadathe CAS/SAFEA International Partnership Program for Creative Research Teams
文摘In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrodynamic corrections. In combination with high-precision measurements, it is feasible to precisely determine a molecular-based value of the proton- to-electron mass ratio. An experimental scheme is presented for measuring the rovibrational transition frequency （v,L） ： （0, 0） → （6,1） in HD＋, which is currently underway at the Wuhan Institute of Physics and Mathematics.
文摘目的探讨法医毒物分析中液相色谱-串联质谱(liquid chromatography-tandem mass spectrome⁃try,LC-MS/MS)法检测血液中毒品类(甲基苯丙胺、吗啡、氯胺酮)、苯二氮蓝卓类(艾司唑仑、咪达唑仑、地西泮、氯硝西泮)和巴比妥类(苯巴比妥)共3大类8种常见药(毒)物的保留时间和离子丰度比的最大允许偏差。方法在2根色谱柱、3种色谱条件下,经液液萃取后采用LC-MS/MS进行检测,分析质量浓度在检出限(limit of detection,LOD)、2倍检出限(2LOD)、定量限(limit of quantitation,LOQ)、1.5倍定量限(1.5LOQ)、2倍定量限(2LOQ)、4倍定量限(4LOQ)和6倍定量限(6LOQ)共7个较低质量浓度时保留时间和离子丰度比的偏差。结果血液添加样品中8种药(毒)物绝对保留时间的偏差在±0.05 min范围内的占98.11%,相对保留时间的偏差在±0.4%范围内的占96.21%。离子丰度比的最大偏差与质量浓度存在高度关联:药(毒)物质量浓度为LOQ及以上时,离子丰度比的绝对偏差和相对偏差都有95%以上分别在±25%和±40%范围内;质量浓度为LOQ以下时,范围可分别扩大至±35%和±50%。结论建议8种常见药(毒)物绝对保留时间的偏差判定范围为±0.1min,相对保留时间的偏差判定范围为±1.0%。质量浓度在LOQ及以上时离子丰度比的绝对偏差判定范围为±25%,相对偏差为±40%,质量浓度在LOQ以下时偏差判定范围可分别扩大至±35%和±50%。
