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A new system for preparing 14C samples was established for a compact accelerator mass spectrometer (GXNU-AMS) at Guangxi Normal University. This sample preparation system consists of three units: a vacuum maintenance unit, a CO2 purification unit, and a CO2 reduction unit, all of which were made of quartz glass. A series of radiocarbon (14C) preparation experiments were conducted to verify the reliability of the system. The recovery rate of graphite obtained was more than 80%. The carbon content in the commercial toner and wood sample was linearly fitted to the CO2 pressure in the measurement unit of the system. The results showed a good linear relationship, indicating that the reliability of the sample preparation system. AMS measurements were conducted on a batch of standard, wood, and dead graphite samples prepared using this system. The results showed that the beam current of 12C- for each sample was more than 40 μA, the carbon contamination introduced during the sample preparation process was ∼ 2 × 10–15, and that the new sample preparation system is compact, low-contamination, and efficient and meets the GXNU-AMS requirements for 14C samples.

Many waterflooding oil fields, injecting water into an oil-bearing reservoir for pressure maintenance, are in their middle to late stages of development. To explore the geological conditions and improve oilfield recovery of the most important well group of the Hu 136 block, located on the border areas of three provinces (Henan, Shandong, and Hebei), Zhongyuan Oilfield, Sinopec, central China, a 14C cross-well tracer monitoring technology was developed and applied in monitoring the development status and recognize the heterogeneity of oil reservoirs. The tracer response in the production well was tracked, and the water drive speed, swept volume of the injection fluid were obtained. Finally, the reservoir heterogeneity characteristics, such as the dilution coefficient, porosity, permeability, and average pore-throat radius, were fitted according to the mathematical model of the heterogeneous multi-layer inter-well theory. The 14C-AMS technique developed in this work is expected to be a potential analytical method for evaluating underground reservoir characteristics and providing crucial scientific guidance for the mid to late oil field recovery process.

In this study, we assembled the complete mitochondrial genome of Yanglong yak (Bos grunniens) from Illumina sequencing reads. The mitochondrial genome is 16,323 bp long with an A + T-biased nucleot...

Dayu yak (Bos grunniens) is a long-furred yak breed from the Qinghai-Tibetan Plateau, and is highly adapted to local high-altitude and cold environments. In this study, its mitochondrial genome was characterized via high-throughput sequencing technology. The genome is 16,323 bp long with an AT-biased base composition (61.0% A + T; light strand), and harbors the typical set of 37 mitochondrial genes and a noncoding control region. Its gene arrangement is identical to those of other bovid taxa. Phylogenetic analysis suggests that Dayu yak is most closely related to Maiwa, Niangya, Qinghai Plateau, Xueduo and Yushu yaks.

The Guangxi Zhuang Autonomous Region in southern China is one of the most typical karst relief areas with various forms, and tiankeng is one of the most typical karst relief forms of the Quaternary Period. In this work, accurate measurements of tiankeng exposure ages were made. The exposure ages of carbonate rocks from the five largest tiankengs in the world, the DaShiwei, HuangJing, ChuanDong, DaTuo, and DaCao tiankengs, were determined by accelerator mass spectrometry to be at least 20–400 thousand years, which provides significant proof for activity of new tectonic movement of the Eurasian continent in the Quaternary.

Tiankeng, a typical Karst relief of the Late Quaternary Period, in the south of China, plays an important role when researching the surface shape and evolution of the Karst relief. The accumulation of Chlorine-36 (T1/2 = 301 ka) through the interaction of cosmic ray particles with Ca, K and Cl in rocks allow it to be used as the ideal nuclide for determination of the exposure age and erosion rate of limestone. In this work, an improved 36Cl sample preparation method for Tiankeng limestone was presented. The Isotope Dilution-AMS technique allows for the simultaneous measurement of 36Cl and Cl with a single AMS sample preparation. The barium introduced during the sample preparation was removed to avoid ionizer poisoning and attain a higher and more stable beam current. The method is particularly suitable for limestone samples, as well as for soil, sediment and water samples.

The jungles of Linyun and Longlin Autonomous Prefecture, located in the heart of the southwestern Guangxi Zhuang Autonomous Region of China, are home to the oldest tea trees (Camellia sinensis) in the world. In the absence of regular annual rings, radiocarbon (14C) dating is one of the most powerful tools that can assist in the determination of the ages and growth rates of these plants. In this work, cores were extracted from large ancient tea trees in a central Longlin rain forest; extraction of carbon was performed with an automated sample preparation system. The 14C levels in the tree cores were measured using accelerator mass spectrometry (AMS) at the University of Tsukuba. These measurements indicated that contrary to conventional views, the ages of trees in these forests range up to ~700 years, and the growth rate of this species is notably slow, exhibiting a long-term radial growth rate of 0.039±0.006 cm/yr. It was demonstrated that 14C analyses provide accurate determination of ages and growth rates for subtropical wild tea trees.

Determining solid-phase gastric emptying (GE) in a human being is an important application in clinical practice as it can provide valuable information for the diagnosis of related digestive diseases. Currently, 99mTc gastric scintigraphy is considered as the gold standard for measuring GE. However, this method suffers from clinical drawback, such as radiation exposure. This study focuses on identifying alternative methods for GE measurement. Carbon-14 accelerator mass spectrometry (AMS) is a useful tool for biomedical projects due to its inherently high sensitivity and dynamic range, low dose and sample size requirements, and relatively short measurement time. However, it has not yet been implemented in GE tests. In this work, 14C AMS methodology was developed for breath samples. Measurements were conducted on a compact, single-stage AMS device at China Institute of Atomic Energy (CIAE). To investigate GE, micro-doses of 14C-octanoic acid, 13C-octanoic acid, and 99mTc were marked along with tracers in the same test meal and subsequently ingested by volunteers. The 14C-octanoic acid breath test (14C-OBT) in combination with AMS showed better counting statistics than those obtained for the 13C-OBT measured using infrared spectroscopy. The results also demonstrate a considerably lower radiation dose than that in 99mTc gastric scintigraphy. This work establishes an alternative method of 14C-AMS tracing to determine solid-phase GE in a human being, which could provide clinical technical support for a GE test and further expand the range of 14C-AMS applications in biomedicine.

Radiocarbon (14C) has become a unique and powerful tracer in source apportionment of atmospheric carbonaceous particles. In this study, the Asia Pacific Economic Cooperation summit (APEC) held in Beijing in 2014 was used as a demonstration to research the source apportionment of atmosphere PM2.5. We used a 200 kV single stage accelerator mass spectrometer recently completed at China Institute of Atomic Energy (CIAE). The PM2.5 samples related to above case were collected, and the characteristics of radiocarbon in organic carbon (OC) and elemental carbon (EC) in samples were analyzed using the AMS. The results show that the Before-APEC pollution emission mode is different from the During-APEC and After-APEC pollution emission modes. For Before-APEC, During-APEC and After-APEC, the average values of fossil carbon fraction of OC are 0.463, 0.431 and 0.615, respectively, and those of EC are 0.644, 0.561 and 0.687. The fossil source contributions of traffic activities using fossil fuels to OC and EC are 15.8 % and 21.9 %, respectively. The fossil source contributions of industrial activities to OC and EC are 38.0 % and 8.2 %, respectively. It is about 7–10 days that is needed to take to regenerate the PM2.5 pollution caused by human activities.

The long lived radioactive nuclide 60Fe is interesting in many research fields such as astrophysics and nuclear physics. Taking the advantage of the high energy of HI-13 tandem AMS system and the high performance of a Q3D magnetic spectrometry at CIAE, the measurement method of 60Fe is being developed. As first step, 58Fe and 58Ni are used for simulating 60Fe and 60Ni for optimizing the measurement conditions and checking the ability of isobar suppression. The results shown that an overall suppression factor of more than 1011 can be obtained by using the ΔE-Q3D technique in combination with a four-anodes gas ionization chamber. Based on the findings a detection sensitivity of 60Fe/Fe ∼ 10−15 can be anticipated.

Elemental calcium plays an important role in human physiology. In order to study the relationship between Ca-intake, Ca-chemical formulation, and Ca-absorptivity, a balance experiment using a 41Ca tracer technique in SD rats was conducted to measure the endogenous fecal calcium and true absorption of calcium. Apparent absorption of calcium was measured as a control to the endogenous calcium labeling experiment. These results show that by using 41Ca labeled endogenous calcium in vivo, researchers could obtain the true calcium absorption data without extrinsic labeling. Therefore, the method was not affected by the chemical structure or type of calcium supplement and might be used in evaluating the absorptivity of marketed calcium supplements.

The cross section of the 60 Ni( n ,2 n ) 59 Ni induced by neutron with energy around 14 MeV is important for a fusion environment. However, the published values are strongly discordant. By taking advantage of the high sensitivity of 59 Ni measurement at China Institute of Atomic Energy (CIAE), determination of the cross section has been carried out. A natural Nickel foil was irradiated by neutrons produce by a T(D, n ) α neutron generator. 57 Co and 58 Co which produced in the Nickel foil were chosen for the neutron fluence determination. Then the ratio of 59 Ni/ 60 Ni for the irradiated sample was determined via accelerator mass spectrometry (AMS) utilizing a 13MV tandem accelerator and a Q3D magnet spectrometry at CIAE. As a result, the cross section of 60 Ni( n ,2 n ) 59 Ni for the incident neutron energy of (14 . 60 ± 0 . 40) MeV was determined to be (426 ± 53) mb.

The determination of uranium isotopic composition in ultra-trace U samples is very important in different fields, especially for the nuclear forensics. A new Accelerator Mass Spectrometry (AMS) technique has been developed for the measurement of uranium isotopic ratios in ng level uranium samples at China Institute of Atomic Energy (CIAE). Recently, the method was further optimized and developed by using a series of blank and standard samples. The results show that the 236U at the femtogram level can be determined in nanogram U samples by the newly developed AMS technique at CIAE. The experimental setup, performances and results will be detailed in this contribution.

The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10−13 and 63Ni/Ni = 2 × 10−12, respectively.