Xiangyang Lu

Genotoxicity Study on Nicotine and Nicotine-Derived Nitrosamine by Accelerator Mass Spectrometry

We have studied DNA adduction with 14C-labe1ed nicotine and nicotine-derived nitrosamine, 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone (NNK), by accelerator mass spectrometry (AMS) in mouse liver at doses equivalent to lowlevel exposure of humans. The dose ranges of nicotine and NNK administered were from 0.4μg to 4.Ox 10^2μg kg b.w.-1, and from 0.1 μg to 2.0x10^4 μg kg b.w.-1, respectively. In the exposure of mice to either nicotine or NNK, the number of DNA adducts increased linearly with increasing dose. The detection limit of DNA adducts was 1 adduct per 1011 nucleotide molecules. This limit is 1-4 orders of magnitude lower than that of other techniques used for quantification of DNA adducts. The results of our animal experiments enabled us to speculate that nicotine is a potential carcinogen. According to the procedure for 14C-labeled-NNK synthesis, we discuss the ultimate chemical speciation of NNK bound to DNA. From the animal tests we derived a directly perceivable relation between tobacco consumption and DNA adduction as the carcinogenic risk assessment.

The use of AMS radiocarbon dating for Xia–Shang–Zhou chronology

Abstract The possibility and problems of using radiocarbon dating to historical chronology are discussed. The current situation of ancient Chinese chronology and the project of Xia–Shang–Zhou chronology are introduced. A chronological study requires the AMS radiocarbon dating with high precision, high reliability and high efficiency. The Peking University AMS facility (PKUAMS) has been upgraded and a series of quality control steps were adopted. To reduce the error of calendar age, wiggle matching with serial samples should be used. Some preliminary results of Xia–Shang–Zhou chronology are presented.

Histone Adduction with Nicotine: A Bio-AMS Study

Based on the study of DNA adduction with nicotine, we have measured the mouse hepatic histone adduction with 14C-labeled nicotine in vivo by bio-accelerator mass spectrometry (bio-AMS). In the exposure of mice to nicotine, the dose range administered was from 0.2 μg to 6.0 μg kg b.w.-1, which was equivalent to a very low level of human exposure to cigarette smoke. The adducts of either histone 1(H1) or histone 3 (H3) with nicotine in mouse liver increased markedly with increasing nicotine dose. Our results have demonstrated that in the study of protein adduction with toxic xenobiotics as a biomarker, the AMS method achieves the highest sensitivity, 4.6x 10-17 mol (46 amol) adducts per mg Hl protein, compared to all the other methods used previously.

Improvements of PKUAMS for precision 14C analysis of the project of Xia–Shang–Zhou Chronology

To meet the requirements of the Xia‐Shang‐Zhou Chronology project, an upgrade of the AMS facility at Peking University has been carried out, commencing in 1996, and a new sample preparation system with high eAciency and low memory has been set up in the Department of Archaeology. A NEC MC-SNICS ion source has been installed and the injection system has been reconstructed. Computer control of the beam line has been implemented using Group 3 ControlNet, and a new data acquisition system has been developed. The alignment and vacuum of the beam line have also been improved. The upgraded system was commissioned in 1998. Subsequent experience has led to eAcient procedures for beam tuning and 14 C/ 13 C measurement. A precision of 0.5% in the 14 C/ 13 C ratio has been achieved. Many samples have now been measured for the Xia‐Shang‐Zhou Chronology project. ” 2000 Elsevier Science B.V. All

PRELIMINARY STUDY ON CLIMATIC SIGNALS OF STABLE ISOTOPES FROM HOLOCENE SPELEOTHEMS UNDER MONSOON CONDITION

Within the East Asian monsoon zone the change in oxygen isotope of Holocene stalagmite is mainly related to monsoon rain rather than to temperature. And carbon isotope can be taken as a comprehensive signal which contains the natural information and the information of anthropogenic activity. Isotopic analysis is also compared with the annual layer records.

Accelerator mass spectrometry at Peking University: experiments and progress

Abstract The Peking University accelerator mass spectrometer (PKUAMS) has been put into routine operation. 14C measurements of archaeological samples with fast cycling injection have shown good results. The new multi-target high-intensity sputtering ion source has been tested and 10Be measurements were carried out with a new detector in which both the stopping of the intense flux of 10B ions and the identification of 10Be ions are performed. 26A1 samples were also measured. While various applications show good prospects for PKUAMS, further upgrade is desirable.

Data analysis and calibration of radiocarbon dating results from the cemetery of the Marquises of Jin

The chronology study of the cemetery of Marquises of Jin is valuable to improving the chronological table of Marquis of Jin family. It is also helpful for improving the chronological table of the Zhou Dynasty. The samples were measured at Peking University (PKUAMS). We also made an interlaboratory check with Isotrace to ensure the accuracy. By careful analysis of archaeological information, we built different models and calibrated by OxCal. The calibration results, both sampling contexts and estimations, are in very good agreement with the historical record. Because the dates of some events correspond to the special part of the curve, the calibration gets very high precision. The calibration result of tomb M93 suggests that its host is Marquis Shangshu instead of Marquis Wen.

The CO2 preparation system for AMS dating at Peking University

Abstract CN analyzer was already applied in CO2 preparation system for AMS dating in the Research Lab for Archaeology & the History of Art in Oxford several years ago [1] . Now a line of combustion with an Elementar Vario EL CHNS elemental analyzer was built in the Dating Lab in the Department of Archaeology at Peking University. This system has many advantages, such as obtaining purer CO2, simultaneously measuring C, N, S etc. elements and C/N. A sample gases (i.e., CO2, CO etc.) recollection system was also built in this lab to recover the CO2 in case of the failure of graphitization.

AMS RADIOCARBON DATING OF THE FENGXI SITE IN SHAANXI, CHINA

The Fengxi site is near the Feng River in Shaanxi Province, China. Feng City was the capital of the vassal state of Zhou, and the Zhou people lived in this area until the end of the Western Zhou. Serial samples of charcoal, bone, and charred millet were collected from the site and dated by accelerator mass spectrometry (AMS). A sequence model with 6 phases of the Western Zhou dynasty was constructed and the 14C ages were calibrated with OxCal v 3.9. The results showed that the site was used from 11701070 BC until 825755 BC, and the Conquest of Shang by King Wu most probably occurred during 10601000 BC.

Ams Radiocarbon Dating Of Tianma-Qucun Site In Shanxi, China

Tianma-Qucun is the biggest site of Western Zhou Dynasty discovered in Shanxi Province, China. It has been recognized as the early capital of Jin, a vassal state of Western Zhou. The territories were granted to the first Marquis of Jin with the title in the early days of Western Zhou. Bone sample series from the site were radiocarbon-dated by accelerator mass spectrometry (AMS) and calibrated with the Oxford calibration program OxCal 3.5. Bayesian analysis of the calibrated ages shows that the earliest residents of the Western Zhou came to Tianma-Qucun area in 1020-940 BC and the lower boundary of the Western Zhou is 796-754 BC, which corresponds well to the historical record 770 BC.