Accelerator Mass Spectrometry Research Articles

MISSMARPLE: MIlan Small-SaMple Automated Radiocarbon Preparation LinE for atmospheric aerosol

Abstract Radiocarbon measurements on the carbonaceous aerosol fractions are an effective tool for aerosol source apportionment. For these measurements, a new sample preparation line (MISSMARPLE: MIlan Small-SaMple Automated Radiocarbon Preparation LinE for atmospheric aerosol) was built in Milan (Italy). MISSMARPLE can separate different carbon fractions (i.e. total carbon (TC), elemental carbon (EC)), automates the sample combustion processes and the CO2 isolation in the “combustion line”, and was designed to handle small samples, of about 50 μg carbon. The CO2 obtained in the combustion line is then reduced to graphite in the graphitization line for subsequent accelerator mass spectrometry (AMS) analysis at the INFN-LABEC in Sesto Fiorentino (Italy). MISSMARPLE was tested for reproducibility of 14C/12C ratio in primary standard samples, for background contamination by the analysis of blank samples (graphite with zero percent Modern Carbon (pMC)), and for accuracy by the analysis of IAEA-C7 for pMC(TC) and NIST RM8785 for pMC(EC) used as secondary standards. Measurements were carried out in different AMS runs. Reproducibility of 14C/12C was within 1.2%; blank values were down to 2.2 ± 0.2 pMC in the latest AMS run, and both IAEA-C7 and NIST RM8785 measurements were within 1σ with the reference value (but for one IAEA-C7 sample within 2.3σ). These results point to MISSMARPLE as a new, valuable tool for aerosol sample preparation for radiocarbon measurements to be exploited not only on traditional 24-h samples but also when small carbon quantities are available (e.g. collected at remote sites or with high temporal resolution).

AMS 14C Dating of the Sites of Digaru-Kolong River Valley, Assam-Meghalaya Foothills, India

Abstract The present study aims to determine the chronology of the past settlement of the different archaeological sites of the Digaru–Kolong River valley (Assam-Meghalaya Foothills), India, based on accelerator mass spectrometry (AMS) 14C dates of seven charcoal samples, five potsherds, and five sediment samples. The archaeological record of the study area consists of ground and polished stone axes and adzes, pottery, and standing or buried megaliths. The samples analyzed were excavated from test pits, and an attempt has been made to correlate the findings with the chronology of the neighboring archaeological region. A site reported in the vicinity of the study area is primarily Neolithic. However, the results from our excavations indicate a time frame for the analyzed artifacts of ca. 240 CE to 1379 CE.

The BIAD Standards: Recommendations for Archaeological Data Publication and Insights From the Big Interdisciplinary Archaeological Database

Abstract This article presents a series of recommendations for the publication of archaeological data, to improve their usability. These 12 recommendations were formulated by archaeological data experts who mined thousands of publications for different data types (including funerary practices, accelerator mass spectrometry dating, stable isotopes, zooarchaeology, archaeobotany and pathologies) during the initial construction of the Big Interdisciplinary Archaeological Database (BIAD). We also include data harmonisation vocabularies utilised for the integration of data from different recording systems. The case studies we cite to illustrate the recommendations are grounded in examples from the published literature and are presented in a problem/solution format. Though practically oriented towards the facilitation of efficient databasing, these recommendations – which we refer to as the BIAD Standards – are broadly applicable by those who want to extract scientific data from archaeological information, those who work with a specific region or theoretical focus and journal editors and manuscript authors. We anticipate that the use of the BIAD Standards will increase the usability, visibility, interoperability and longevity of published data and also increase the citations of those publications from which data were mined. The Standards will also help frame a unified foundation to support the continued integration of the natural sciences with archaeological research in the future.

The Arpu Kuilpu meteorite: In‐depth characterization of an H5 chondrite delivered from a Jupiter Family Comet orbit

AbstractOver the Nullarbor Plain in South Australia, the Desert Fireball Network detected a fireball on the night of June 1, 2019 (7:30 pm local time), and 6 weeks later recovered a single meteorite (42 g) named Arpu Kuilpu. This meteorite was then distributed to a consortium of collaborating institutions to be measured and analyzed by a number of methodologies including SEM‐EDS, EPMA, ICP‐MS, gamma‐ray spectrometry, ideal gas pycnometry, magnetic susceptibility measurement, μCT, optical microscopy, and accelerator and noble gas mass spectrometry techniques. These analyses revealed that Arpu Kuilpu is an unbrecciated H5 ordinary chondrite, with minimal weathering (W0‐1) and minimal shock (S2). The olivine and pyroxene mineral compositions (in mole%) are Fa: 19.2 ± 0.2 and Fs: 16.8 ± 0.2, further supporting the H5 type and class. The measured oxygen isotopes are also consistent with an H chondrite (δ17O‰ = 2.904 ± 0.177; δ18O‰ = 4.163 ± 0.336; Δ17O‰ = 0.740 ± 0.002). Ideal gas pycnometry measured bulk and grain densities of 3.66 ± 0.02 and 3.77 ± 0.02 g cm−3, respectively, yielding a porosity of 3.0% ± 0.7. The magnetic susceptibility of this meteorite is log χ = 5.16 ± 0.08. The most recent impact‐related heating event experienced by Arpu Kuilpu was measured by 40Ar/39Ar chronology to be 4467 ± 16 Ma, while the cosmic ray exposure age is estimated to be between 6 and 8 Ma. The noble gas isotopes, radionuclides, and fireball observations all indicate that Arpu Kuilpu's meteoroid was quite small (maximum radius of 10 cm, though more likely between 1 and 5 cm). Although this meteorite is a rather ordinary ordinary chondrite, its prior orbit resembled that of a Jupiter Family Comet (JFC) further lending support to the assertion that many cm‐ to m‐sized objects on JFC orbits are asteroidal rather than cometary in origin.

A recent date for the dog (Canis familiaris) from Mapala Rockshelter and implications for associated mammal community changes in subalpine Highland West New Guinea

The arrival of the dog (Canis familiaris) in Australasia is believed to have had major impacts on the region’s ecosystems as well as human society and organisation. Very little is known about the antiquity of the dog in New Guinea due to a paucity of fossil specimens of secure antiquity, particularly in the Highlands. Here, we report the direct dating of a partial dog cranium from Mapala Rockshelter, a subalpine site at ∼4000 m asl in the Sudirman Range. Recovered in 1972 from a bone-rich layer in the cave floor above a basal charcoal date of about 5500 BP, this individual has been considered a possible early example of dog in Australasia. An Accelerator Mass Spectrometry date from maxillary bone shows that the Mapala dog is far more recent (491 ± 19 BP, or 536–501 cal BP). Our finding is of relevance to understanding the antiquity of dog in the Highlands of New Guinea, and also for the wild dog populations which exist across this large area. The date is also the first for the site’s mammal-rich fossiliferous sedimentary unit, providing a chronological context for Late Holocene turnover in the composition of the local fauna. The most notable of these changes include the regional extinction of two Thylogale spp. and the invasion of Pseudochirops cupreus into subalpine western New Guinea environments.

Cosmic rays, radiocarbon and the beginning of high-energy particle physics: Marietta Blau and the “disintegration stars”

Abstract This brief review describes the discovery of cosmic rays by Victor Hess from the Vienna Radium Institute and the later contribution of Marietta Blau through her observation of “disintegration stars” in photographic emulsion plates exposed to cosmic-ray bombardment. Marietta Blau, a nearly forgotten cosmic-ray pioneer from the Vienna Radium Institute, developed the nuclear emulsion technique for studying nuclear reactions, eventually discovering the disintegration of nuclei through high-energy cosmic rays. Blau survived the Holocaust by escaping to Mexico City from 1939 to 1944. Starting in 1948 at Columbia University, later as a staff member of Brookhaven National Laboratory and then University of Miami, she performed fundamental and original research with nuclear emulsions exposed to 3-GeV protons at the Brookhaven Cosmotron and to 6-GeV protons at the Berkeley Bevatron. Blau returned to Vienna in 1960, where at the Radium Institute a classical β-decay counting facility for radiocarbon dating had been installed, which was finally superseded by the Vienna Environmental Research Accelerator (VERA), a modern versatile accelerator mass spectrometry facility.

Development of an Interdisciplinary Approach to the Radiocarbon Dating of Earth Mortars from Alula Old Town (Saudi Arabia). Integration of Building Archaeology, Mortar Analysis and Radiocarbon Dating

Abstract This paper discusses the approach used to identify the most relevant chronological information on the historic development of the abandoned site of AlUla Old Town, in the northwest of the Kingdom of Saudi Arabia (Western Asia). The approach is based on the use of the radiocarbon method to date earth mortars samples and soil layers used to create the constructive sequence of some buildings and, in turn, the chronological evolution of the site. Eleven samples of organic material (i.e., charcoal and vegetable fibers) were carefully removed from mortar samples and soil levels from six buildings and structures in the northern and southern areas of the town. Buildings and soil layers were chosen for their stratigraphic relevance and conservation conditions, based on an initial archaeological analysis of both, buildings and underground structures. Laboratory-based mortar analysis led to the characterization of the mortar’s inorganic fraction, and to the isolation of the organic material for the radiocarbon dating. Results from the accelerator mass spectrometry (AMS) laboratory provides evidence of a Late Mamluk/Early Ottoman constructive phase (i.e., 15th–17th c. AD) of the Old Town that was only partially known until very recently. Furthermore, the results allowed the identification of an Ottoman phase (i.e., 17th–19th c. AD) during which most of the buildings and structures were rebuilt, and of a Late Ottoman phase (i.e., 19th–20th c. AD) representing the most recent interventions before the end of the Ottoman occupation of the area.

Phenotypic diversity in early Australian dingoes revealed by traditional and 3D geometric morphometric analysis

The dingo is a wild dog endemic to Australia with enigmatic origins. Dingoes are one of two remaining unadmixed populations of an early East Asian dog lineage, the other being wild dogs from the New Guinea highlands, but morphological connections between these canid groups have long proved elusive. Here, we investigate this issue through a morphometric study of ancient dingo remains found at Lake Mungo and Lake Milkengay, in western New South Wales. Direct accelerated mass spectrometry (AMS) radiocarbon dates from an ancient Lake Mungo dingo demonstrate that dingoes with a considerably smaller build than the predominant modern morphotype were present in semi-arid southeastern Australia c.3000–3300 calBP. 3D geometric morphometric analysis of a near-complete Mungo cranium finds closest links to East Asian and New Guinean dogs, providing the first morphological evidence of links between early dingoes and their northern relatives. This ancient type is no longer extant within the range of modern dingo variability, but populations from nearby southeastern Australia show a closer resemblance than those to the north and west. Our results reaffirm prior characterisations of regional variability in dingo phenotype as not exclusively derived from recent domestic dog hybridisation but as having an earlier precedent, and suggest further that the dingo’s phenotype has changed over time.

Provenance Analysis of the Northern Offshore Mud Area of the Shandong Peninsula, China, Spanning the Last 2000 Years

The mud area in the northern offshore of the Shandong Peninsula constitutes a dynamic source–sink system in China’s continental shelf and is a hotspot for research. However, the provenance of the sediments remains controversial, and the depositional environment is not yet fully understood. This paper performed accelerator mass spectrometry 14C dating, grain-size analysis, clay mineralogic analysis, and geochemical analysis of the ZZ04 sediment core. The results showed that this core primarily comprises silt and clay, reflecting weak sedimentary hydrodynamic conditions and stable deposition. The clay mineral assemblage—illite, smectite, chlorite, and kaolinite—indicates strong physical weathering. The provenance of the mud area was mainly from the Yellow River, Shandong Peninsula rivers, and Yangtze River, highlighting its multi-source characteristics. The smectite/(illite + chlorite) ratio in the ZZ04 core serves as a mineralogical indicator of the East Asian summer monsoon (EASM). Eight significant East Asian winter monsoon (EAWM) intensifications were identified, correlating with global cooling events similar to those at 1.89, 1.4, 1.03, and 0.62 thousand years ago. During the EAWM period, the coastal current and the Yellow Sea warm current play crucial roles in the transportation of matter and heat flux in the mud area. In contrast, during the EASM period, the sediments are predominantly sourced from the Shandong Peninsula rivers, contributing terrigenous materials shaped by chemical weathering.

C− generation by charge exchange with non-metallic gas for positive ion mass spectrometry

Carbon positive ion mass spectrometry technology(C-PIMS) is a new type of mass spectrometry technology using the opposite charge exchange process of accelerator mass spectrometry (AMS). There is a plan at Peking University to build 14C-PIMS with the study of a compact 2.45 GHz ECR ion source for C2+ production and a charge exchange cell (CXC) for C2+ to C− conversion. In this paper, the profile of carbon ion source and CXC is introduced and the generation of C− ions is investigated. In experiment, five non-metallic gas targets are tested. 19 μA@90 keV C− beam is obtained from C2+ using the ethylene target. It is found that gas targets with low first ionization energy favor the generation of C−. In addition, the charge exchange efficiency at different beam energies (25 keV–90 keV) is investigated. In terms of theory, the mechanisms of resonant and non-resonant charge exchange processes are introduced to analyze the experimental results. Moreover, the charge exchange from C+ to C− is studied and the feasibility of C+-PIMS is discussed since 2.45 GHz ECR ion source produce more C+ ions. It is found that 139 μA@45 keV C− beam can be obtained from C+ using the methane target.

Technical note: Optimizing the in situ cosmogenic 36Cl extraction and measurement workflow for geologic applications

Abstract. In situ cosmogenic 36Cl analysis by accelerator mass spectrometry (AMS) is routinely employed to date Quaternary surfaces and assess rates of landscape evolution. However, standard laboratory preparation procedures for 36Cl dating require the addition of large amounts of isotopically enriched chlorine spike solution; these solutions are expensive and increasingly difficult to acquire from commercial sources. In addition, the typical workflow for 36Cl dating involves measuring both 35Cl/37Cl and 36Cl/Cl concurrently on the high-energy (post-accelerator) end of the AMS system, but 35Cl/37Cl determinations using this technique can be complicated by isotope fractionation and system memory during measurement. The traditional workflow also does not provide 36Cl extraction laboratories with the data needed to calculate native Cl concentrations in advance of 36Cl/Cl measurements. In light of these concerns, we present an improved workflow for extracting and measuring chlorine in geologic materials. Our initial step is to characterize 35Cl/37Cl on sample aliquots of up to ∼1 g prepared in Ag(Cl, Br) matrices, which greatly reduces the amount of isotopically enriched spike solution required to measure native Cl content in each sample. To avoid potential issues with isotope fractionation through the accelerator, 35Cl/37Cl is measured on the low-energy, pre-accelerator end of the AMS line. Then, for 36Cl/Cl measurements, we extract Cl as AgCl or Ag(Cl, Br) in analytical batches with a consistent total Cl load across all samples; this step is intended to minimize source memory effects during 36Cl/Cl measurements and allows the preparation of AMS standards that are customized to match known Cl contents in the samples. To assess the efficacy of this extraction and measurement workflow, we compare chlorine isotope ratio measurements on seven geologic samples prepared using standard procedures and the updated workflow. Measurements of 35Cl/37Cl and 36Cl/Cl are consistent between the two workflows, and 35Cl/37Cl values measured using our methods have considerably higher precision than those measured following standard protocols. The chemical preparation and measurement workflow presented here (1) reduces the amount of isotopically enriched chlorine spike used per rock sample by up to 95 %; (2) identifies rocks with high native Cl concentrations, which may be lower priority for 36Cl surface exposure dating, at an early stage of analysis; and (3) allows laboratory users to maintain control over the total chlorine content within and across analytical batches. These methods can be incorporated into existing laboratory and AMS protocols for 36Cl analyses and will increase the accessibility of 36Cl dating for geologic applications.

The Pharmacokinetics, Metabolism, and Clearance Mechanisms of Ritlecitinib, a Janus Kinase 3 and Tyrosine-Protein Kinase Family Inhibitor, in Humans.

Ritlecitinib is an oral once-daily irreversible inhibitor of Janus kinase 3 and tyrosine-protein kinase family being developed for the treatment of moderate-to-severe alopecia areata. This study examined the disposition of ritlecitinib in male participants following oral and intravenous administration using accelerator mass spectroscopy methodology to estimate pharmacokinetic parameters and characterize metabolite profiles. The results indicated ritlecitinib had a systemic clearance of 43.7 L/h, a steady state volume of distribution of 73.8 L, extent of absorption of 89%, time to maximum plasma concentration of ∼0.5 hours, and absolute oral bioavailability of 64%. An observed long terminal half-life of total radioactivity was primarily attributed to ritlecitinib binding to plasma albumin. Ritlecitinib was the main circulating drug species in plasma (∼30%), with one major pharmacologically inactive cysteine conjugated metabolite (M2) at >10%. Oxidative metabolism (fractional clearance 0.47) and glutathione-related conjugation (fractional clearance 0.24) were the primary routes of elimination for ritlecitinib with the greatest disposition of radioactivity shown in the urine (∼71%). In vitro phenotyping indicated ritlecitinib cytochrome P450 (CYP) fraction of metabolism assignments of 0.29 for CYP3A, 0.09 for CYP2C8, 0.07 for CYP1A2, and 0.02 for CYP2C9. In vitro phenotyping in recombinant human glutathione S-transferases indicated ritlecitinib was turned over by a number of cytosolic and microsomal enzyme isoforms. SIGNIFICANCE STATEMENT: This study provides a detailed understanding of the disposition and metabolism of ritlecitinib, a JAK3 and TEC family kinase inhibitor for alopecia areata in humans, as well as characterization of clearance pathways and pharmacokinetics of ritlecitinib and its metabolites. As an AMS-based ADME study design, we have expanded on reporting the standard ADME endpoints, providing key pharmacokinetic parameters, such as clearance, volume of distribution, and bioavailability, allowing for a more comprehensive understanding of drug disposition.

Holocene paleolimnological changes in rundvågshetta lakes in the Soya Coast region and their paleoenvironmental significance with glacial isostatic adjustment in East Antarctica

This study investigated Holocene paleolimnological changes inferred from a multi-proxy dataset of C, N, and S elements, biomarkers, and microscopic observations of microalgae and cyanobacteria in sediment cores from two Rundvågshetta lakes (Maruwanminami-ike and Maruwan-oike) in the Soya Coast region of Antarctica, along with sedimentary facies and accelerator mass spectrometry 14C dating. We discuss biological production and sources, the transition from marine to brackish and lacustrine environments in the lakes, paleoenvironmental changes, transition ages, and relative sea level (RSL) falls (or subsidence) from glacial isostatic adjustment (GIA) in the Soya Coast region. The ages of the Maruwanminami-ike (MwS4C-01, length 147 cm) and Maruwan-oike sediment cores (Mw4C-01, length 226 cm) were 1.4 (5.8 cm core depth)–4.9 and 2.3–5.7 cal ker BP, respectively. The local reservoir effects of the Rundvågshetta lakes were very high, possibly because of the influence of dead carbon in the glacially eroded marine sediments and bed rock. The coastal marine environments of Lakes Maruwanminami-ike (4.9–2.6 cal ker BP) and Maruwan-oike (5.7–3.3 cal ker BP) were characterized by low biological production. A transition period marked by a stratified brackish lake environment in Lakes Maruwanminami-ike (2.6–2.4 cal ker BP) and Maruwan-oike (3.3–2.9 cal ker BP) was characterized by stratified conditions with an anoxic layer at the bottom of the photic zone. The freshwater lake environment of Lake Maruwanminami-ike [(65.6–0 cm, 2.4–1.4 (5.8 cm core depth) cal kyr BP)] was characterized by high biological (cyanobacteria and green algae) production, while that of Lake Maruwan-oike (2.9–2.3 cal ker BP) was characterized by low biological production due to the influence of glacial clay. Around 7.2–3.0 cal ka BP in the Holocene was probably a warm period, and progressive glacial retreat with RSL fall occurred during the warm periods in the Soya Coast region. The RSL falls of all raised beaches and isolated basins in the Soya Coast region ranged from 0.36 ± 0.03–4.4 ± 0.5 mm/yr with an average 2.1 ± 0.2 mm/yr (standard deviation, SD). They were similar to GNSS–based GIA–induced uplift with an average of 2.4 ± 1.5 mm/yr (SD) at Soya Coast region.

OSL re-dating and paleoclimate of Laoya Cave in Guizhou Province, southwest China

Laoya Cave is a significant prehistoric human site in Guizhou Province, Southwest China, and optically stimulated luminescence (OSL) and a Bayesian depositional model were used to update the chronology of the cave. Six OSL samples were dated to 16.7 ± 1.2, 18.0 ± 1.1, 28.8 ± 2.3, 32.1 ± 2.8, 57.7 ± 6.5, and 74.0 ± 5.9 ka, respectively, and the Bayesian deposition model has provided a coherent chronological framework, revealing boundaries with median ages of 18.5, 25.0, 27.5, 28.6, 29.9, and 74.4 ka for Boundaries 1/2, 2/3, 3/4, 4/5, 5/6, and 6/9, respectively. By comparing the new chronological framework with the related records of paleoclimate and human activities, we gain insight into the relationship between the environment and Paleolithic hominins at different times. During relatively warmer periods, humans tend to spread, while in relative colder climates, they tend to rely more heavily on caves and employ hunting strategies with an equal age distribution. These survival strategies help humans prevent the threats of cold weather. Additionally, the analysis of OSL dating results uncovers a discrepancy between OSL and accelerator mass spectrometry radiocarbon (AMS 14C) dating methods, with AMS 14C dates generally appearing older at later ages (<∼30 ka). This phenomenon may be due to disturbances caused by human activity, and OSL dating may recognize this to some extent.

New data on tributary terraces and a reappraisal of the incision history of the Jinshan Gorge, middle Yellow River

River channel profiles and river terraces are two typical landscape features to investigate river incision history. However, incision history inferred from the two markers can be inconsistent. For example, along the Jinshan Gorge in the middle Yellow River, pseudo-terraces (a virtual metric derived from channel profile modelling) suggest a recent acceleration in incision rates only in the southern gorge, and the northern keeps steady, while river terraces in the trunk channel indicate recently increased incision rates all along the gorge. To mitigate these discrepancies, we investigate six tributaries along the Jinshan Gorge by mapping and dating several strath terraces at various distances from the confluence to the trunk channel. By comparing tributary terraces of similar age, we find generally increasing incision rates towards the confluence with the trunk river in the southern Jinshan Gorge. North to south increasing incision rates along the gorge are also observed from coeval tributary terraces. In addition, two different landscapes between the southern and northern tributaries near the confluence are recognized, one with a deeply incised gorge and another one with floodplains, suggesting incision rate in the northern gorge is steady through time. Integrating the new infrared stimulated luminescence (IRSL) and Accelerator Mass Spectrometry (AMS) 14C data from tributaries with the abundant literature data of terrace samples mostly in the Jinshan Gorge dated with various methods, we suggest published ages from optically stimulated luminescence (OSL) might be too young. The methodological limitation associated to the dating method can explain the observed mismatch of incision history in the northern gorge inferred from pseudo-terraces and from river terraces in the trunk channel, and reconcile some contradicting patterns in published trunk terrace data.

Reaching environmental levels of 244Pu by accelerator mass spectrometry at the Centro Nacional de Aceleradores

244Pu (T1/2 = 81 My) is the longest-lived, most minor, and the most understudied Pu isotope. The anthropogenic production of 244Pu is linked to nuclear detonations. Reported 244Pu/239Pu atom ratios in environmental samples range from below 10−6 to above 10−3. This work discusses the performance of the 1 MV Accelerator Mass Spectrometry system at the Centro Nacional de Aceleradores (CNA, Seville, Spain) to analyse 244Pu at environmental levels. The presence of 232Th traces in the Pu sample limits the sensitivity of the technique through the formation of the diatomic trication (232Th12C)3+, of mass 244 u, which must be suppressed by adjusting the stripper gas pressure. A244Pu background of 0.0075 fg (2 × 104 at) is demonstrated for samples that have undergone a chemical treatment. The reliability of the technique is proved through the analysis of three reference sediments provided by the International Atomic Energy Agency (IAEA-412, IAEA-465, IAEA-385). 244Pu results are complemented with 239Pu, 240Pu, 241Pu and 236U and their relative isotopic abundances are discussed.

The coupling between tectonic uplift and climate change recorded by the Yellow River terraces during the Zoige basin excavation in the northeastern Tibetan Plateau

Understanding the processes of fluvial geomorphic evolution is based on thorough evaluation of how rivers respond to tectonic activity and climatic change, with river terraces representing a key archive of alternating deposition and incision in response to such forcing, enabling an excellent means for correlation with tectonic and climatic records. An example presented here points to a difference in fluvial response to climate fluctuations along a trunk river and its tributary: the Yellow River and its tributary the Xike River, which has incised the Lajia Gorge to pirate the Zoige Basin, in the eastern Tibetan Plateau. Based on Accelerator Mass Spectrometry 14C dating, the chronological sequence of basin fill top and fluvial terraces below has been established, defining the drainage reorganization of the Yellow River excavation through the Zoige Basin since the Last Glacial Maximum. Spatial and stratigraphic comparison between the two fluvial sequences, combined with correlation with high-resolution climatic records, indicates that the tributary Xike River formed more terraces in response to trunk incision (base-level variation), climatic fluctuations, and underlying weak bedrock than the Yellow River. Thus, our results not only demonstrate a combined archive of climatic fluctuation and tectonic uplift recorded in the fluvial terrace sequences, but also suggest that the generation of fluvial terraces may be influenced by the underlying bedrock within the same tectonic and climatic settings.

Cosmogenic radionuclide Beryllium-7 and Beryllium-10 characteristics and influencing factors in different natural climate regions, China

The cosmogenic radionuclide 7Be (T1/2: 53.29 days) and 10Be (T1/2: 1.39 My), as unique tracers, play an excellent indicative role in atmospheric environmental changes and Earth surface processes. Currently, their different characteristics and influencing factors in various natural climate environments are still vague. Here, we used a state-of-the-art accelerator mass spectrometry to synchronously measure the ultra-trace 7Be and 10Be in aerosols, obtaining the spatial and temporal variability of daily-resolution atmospheric 7Be and 10Be in different natural climate regions (n = 11) of China. The survey results show that the 10Be and 7Be concentrations in the central/southern regions of China (22–38°N, 85–119°E) in 2020/21 are (0.5–18.7)·104 and (0.4–6.1)·104 atoms·m−3, respectively, with 10Be/7Be ratios of 0.7–3.3. Except for the Tibetan Plateau, there are differences in the concentration thresholds of 10Be and 7Be in various regions, especially in 10Be concentration. These 10Be/7Be thresholds are consistent in areas with an altitude range of 4–3420 m a.s.l and reach their highest values throughout the spring of the year. The analysis results indicate that both 7Be and 10Be are influenced by local meteorological conditions such as rainfall and boundary layer disturbances, while also exhibiting different distribution states. This distribution states is due to the re-suspended soil dust 10Be interference caused by soil wind erosion to varying degrees in different regions, with an average contribution to aerosol 10Be of 5.0 ± 2.6 %–24.2 % ± 13.3 %, and is controlled by local annual rainfall (r = 0.8, p < 0.01). Furthermore, unlike the characteristics of 10Be and 7Be concentrations influenced by local meteorological conditions, the daily variation of corrected 10Be/7Be exhibits independence from meteorological processes other than stratosphere troposphere transport, and its significant seasonal oscillations indicate changes in atmospheric circulation in the East Asian monsoon region.

Characterization of meteoric 10Be in certified reference materials for use in internal control standards

In recent decades, interest in the measurement of 10Be has increased due to its relevance in various fields of science. Trace amounts of 10Be produced from meteoric sources require sensitive accelerator mass spectrometry (AMS) measurements and robust sample preparation. The extraction, separation, and preparation of the appropriate oxide form for AMS require extensive and careful laboratory processing and certified reference materials to validate the chemical performance of the protocols used and the calibration of the AMS system in the measurement. In this work, the meteoric 10Be concentrations in two certified reference materials are characterized to establish their suitability as internal control standards for laboratory chemical preparation and AMS measurements of this radioisotope in our laboratory and the whole AMS community.

Development of a sensitive LC-MS/MS assay to support human microdose study for an oral agonist of the GLP-1 receptor.

Aim: The purpose of this work was to determine the feasibility of supporting a clinical microdose study for PF-06882961 (danuglipron), an oral small molecule agonist of the GLP-1 receptor, by LC-MS/MS. Methodology: Statistical instrument parameteroptimization using response surface methodologywas employed to develop a LC-MS/MS method for the analyte, PF-06882961. Results: An LC-MS/MS method was developed and validated to support a proof of concept microdose pharmacokinetics preclinical study in monkeys, administered PF-06882961 (0.005mg total, average dose=0.0007mg/kg) via intravenous bolus injection. Conclusion: The present study demonstrated the feasibility of analyzing human microdose plasma samples for PF-06882961 by LC-MS/MS, instead of accelerator mass spectrometry, thereby reducing cost and eliminating synthesis and exposure to 14C labeled material.