High-precision Mass Spectrometry Research Articles

High-resolution sedimentary cyclostratigraphy and astronomical signals in the Upper Ordovician of Southwest China

During the Late Ordovician, a series of significant biotic and geological events occurred globally and more specifically in South China. The development of a high-resolution orbital cyclostratigraphic framework and a precise radioisotope dating has greatly enhanced our understanding of the factors controlling these events. In this study, quantitative proxies for palaeo-water depths, derived from sedimentological analyses, serve as indicators for orbital cyclostratigraphic assessment.Relatively shallow-marine carbonates with well-developed shallowing-upward cycles were deposited in the western Yangtze Platform during the Late Ordovician. High-resolution geochronological data were obtained from high-precision isotope dilution thermal ionization mass spectrometry (ID-TIMS) zircon dating of K-bentonite beds at the studied section. This facilitated sedimentary facies and environmental analyses, as well as the recognition of sedimentary cycles. Based on mud content, bioclastic content, and laminations, four sedimentary facies, twelve sedimentary microfacies, and forty-eight shallowing-upward sedimentary cycles were identified in the Daduhe Formation.Through comparative time series analysis of depth rank, lime mudstone-calcareous mudstone binary data, non-carbonate content, and anhysteretic remanent magnetization (ARM), astronomical cycles and trends in sedimentation rates have been identified. This study confirms the reliability of radioisotope dating, establishing a 0.46 Myr duration for the Dicellograptus complexus graptolite biozone and a 0.96 Myr duration for the Paraorthograptus pacificus graptolite biozone, both with an empirical uncertainty of 0.1 Myr. This research proposes a reliable method for identifying astronomical cycles through high-precision sedimentary microfacies and cyclostratigraphy, in comparison with rock magnetic cyclostratigraphy studies.

Orders of Magnitude Improved Cyclotron-Mode Cooling for Nondestructive Spin Quantum Transition Spectroscopy with Single Trapped Antiprotons.

We demonstrate efficient subthermal cooling of the modified cyclotron mode of a single trapped antiproton and reach particle temperatures T_{+}=E_{+}/k_{B} below 200mK in preparation times shorter than 500s. This corresponds to the fastest resistive single-particle cyclotron cooling to subthermal temperatures ever demonstrated. By cooling trapped particles to such low energies, we demonstrate the detection of antiproton spin transitions with an error rate <0.000 023, more than 3 orders of magnitude better than in previous best experiments. This method has enormous impact on multi-Penning-trap experiments that measure magnetic moments with single nuclear spins for tests of matter and antimatter symmetry, high-precision mass spectrometry, and measurements of electron g factors bound to highly charged ions that test quantum electrodynamics and establish standards for magnetometry.

SURFACTANT–POLYMER FLOODING: GEOCHEMICAL MONITORING OF THE PROPERTIES OF FORMATION FLUIDS AT THE IMPACT AREA

Chemical flooding methods improve oil extraction after standard waterflooding processes. Chemical EOR methods modify different properties of fluids and/or rock to mobilize the remaining oil. It is expected that the residual oil will be different in properties than conventional. A new technology is presented to study a surfactant–polymer flooding, based on a periodic sampling and measuring properties of oil and water during 15 months. The study area is a terrigenous reservoir with 3 chemical injection wells and 16 production wells. High-precision mass spectrometry methods were carried out on each sample, which made it possible to evaluate the effectiveness of ongoing work on chemical flooding. At each sampling date, 2D reservoir model was built to track these changes in the study area. It is shown that the composition of the water has changed - highly permeable channels were closed and formation waters were involved in the production. The properties of oil have also changed - depending on the site of impact, there are areas with more degraded oil in production after the injection of chemicals. Geochemical monitoring shows the redistribution of filtration flow directions in the reservoir volume.

Formation Enthalpies of C3 and C4 Brominated Hydrocarbons: Bringing Together Classical Thermodynamics, Modern Mass Spectrometry, and High-Level Ab Initio Calculations.

The enthalpies of formation of brominated C3-C4 hydrocarbons were critically evaluated using experimental data sources ranging from classical thermodynamics methods to modern high-precision mass spectrometry and reported in a time span of a century. The experimental data were used in conjunction with the results of modern high-level ab initio calculations. To facilitate quantitative analysis, a recently developed local coupled cluster-based computational protocol was extended to organic compounds containing univalent Br. Several erroneous data sources were identified in a course of the study. Possible reasons for the inconsistency between the ΔfHm° values recommended by the Committee on Data of the International Science Council (CODATA) and Active Thermochemical Tables for HBr in the gas and aqueous solution were discussed. The most up-to-date recommendations based on the comprehensive analysis of collected information are provided for 23 brominated hydrocarbons. For several compounds under consideration, the recommended values were previously lacking, while improved values and uncertainties were obtained for those with existing recommendations.

Systematic analysis of the pharmacology of standardized extracts of human placenta

Currently, the study of promising “biogenic stimulants” that exhibit pathogenetic effects in relation to various diseases continues. The first results of studies of peptide “biogenic stimulants” based on human placenta extracts (HPE) were obtained by Prof. Filatov VP in the thirties of the 20th century. Currently, through modern methods of postgenomic pharmacology (including high-precision mass spectrometry, enzyme-linked immunosorbent assay and sequencing), it becomes possible to obtain new data on the structure and functions of peptide extracts, which indicates the molecular pharmacological mechanisms of their action. Analysis of peptide fractions of individual standardized ENPs and the results of clinical studies of these ENPs indicate a wide range of clinical applications of ENPs: (1) liver diseases; (2) viral diseases — COVID-19, etc.; (3) diseases accompanied by iron overload and hyperferritinemia; (4) chronic fatigue syndrome; (5) skin diseases; (6) joint pathologies; (7) acceleration of wound healing; (8) diseases associated with the female reproductive system.

A Bird’s Eye View of Quantitative Proteome of Tumor Tissues from Lung Cancer Patients by a High Precision Mass Spectrometry Method

A Bird’s Eye View of Quantitative Proteome of Tumor Tissues from Lung Cancer Patients by a High Precision Mass Spectrometry Method

MULTIPULSED MAGMATISM AND DURATION OF THE HYDROTHERMAL SYSTEM OF THE GIANT JIAMA PORPHYRY Cu SYSTEM, TIBET, CHINA

Abstract Jiama is the largest porphyry-skarn ore system in the Gangdese metallogenic belt, Tibet. It is composed of porphyry Cu-Mo, Cu-polymetallic skarn, Cu-Pb-Zn manto, and distal vein Au orebodies with associated Ag, W, and Bi. However, the precise timing of the magmatism and hydrothermal events at Jiama remains obscure. Here, using high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb zircon dating of ore-bearing and post-ore intrusions, we accurately constrain the lifespan of magmatism and hydrothermal mineralization. Monzogranite porphyry dikes are cut by Cu-Mo vein mineralization in the deeper part of the system, indicating that they were emplaced pre-ore, and yield a crystallization age of 15.534 ± 0.007 Ma (mean square of weighted deviates [MSWD] = 0.99, n = 6). A granodiorite porphyry that cuts the monzogranite porphyry and hosts vein and disseminated chalcopyrite and molybdenite is considered synchronous with ore and yields a crystallization age of 15.368 ± 0.007 Ma (MSWD = 1.01, n = 5). These two phases of intrusions are cut by quartz-diorite porphyry bodies, which yield a crystallization age of 15.076 ± 0.006 Ma (MSWD = 0.13, n = 6) and contain weak, subeconomic Cu and almost no molybdenum mineralization. A post-ore barren quartz monzonite porphyry yields a crystallization age of 14.925 ± 0.006 Ma (MSWD = 1.12, n = 6). The lifespan of magmatism at Jiama is thus about 0.61 m.y. The difference with previous molybdenite Re-Os isochron ages from the porphyry (14.7 ± 0.3 Ma), hornfel (14.7 ± 0.4 Ma), and skarn (15.4 ± 0.2 Ma) suggests that high-precision chronology is required to decipher accurate timing of mineralization in porphyry systems such as Jiama. The 40Ar/39Ar ages of hydrothermal biotite coexisting with molybdenite in monzogranite porphyry and hornfels are 15.25 ± 0.17 Ma (MSWD = 1.6) and 15.25 ± 0.24 Ma (MSWD = 0.14), respectively, slightly younger than the granodiorite porphyry and older than weakly mineralized quartz diorite porphyry, which represents the time of the ore-forming hydrothermal event. Thus, Jiama is the product of pulsed magmatism during which a short-lived hydrothermal event formed the giant Cu polymetallic system.

Novel 13C enrichment technique reveals early turnover of DHA in peripheral tissues

The brain is rich in DHA, which plays important roles in regulating neuronal function. Recently, using compound-specific isotope analysis that takes advantage of natural differences in carbon-13 content (13C/12C ratio or δ13C) of the food supply, we determined the brain DHA half-life. However, because of methodological limitations, we were unable to capture DHA turnover rates in peripheral tissues. In the current study, we applied compound-specific isotope analysis via high-precision GC combustion isotope ratio mass spectrometry to determine half-lives of brain, liver, and plasma DHA in mice following a dietary switch experiment. To model DHA tissue turnover rates in peripheral tissues, we added earlier time points within the diet switch study and took advantage of natural variations in the δ13C-DHA of algal and fish DHA sources to maintain DHA pool sizes and used an enriched (uniformly labeled 13C) DHA treatment. Mice were fed a fish-DHA diet (control) for 3 months, then switched to an algal-DHA treatment diet, the 13C enriched-DHA treatment diet, or they stayed on the control diet for the remainder of the study time course. In mice fed the algal and 13C enriched-DHA diets, the brain DHA half-life was 47 and 46 days, the liver half-life was 5.6 and 7.2 days, and the plasma half-life was 4.7 and 6.4 days, respectively. By using improved methodologies, we calculated DHA turnover rates in the liver and plasma, and our study for the first time, by using an enriched DHA source (very high δ13C), validated its utility in diet switch studies.

G-C3N4 as Photocatalyst for the Removal of Metronidazole Antibiotic from Aqueous Matrices under Lab and Pilot Scale Conditions

The presence of pharmaceuticals in water is a problem of utmost importance due to the various adverse effects that these compounds may have on aquatic organisms and also humans. Since conventional wastewater treatment plants fail to efficiently remove many of these compounds, new techniques such as heterogeneous photocatalysis have been developed that are capable of degrading them. In this study, graphitic carbon nitride (g-C3N4) was used as photocatalyst to remove metronidazole (MTZ), which is a widely prescribed antibiotic that has been reported as a potential carcinogen. The experiments were performed under lab and pilot scale conditions. During the lab scale experiments, 90.6% of the initial pharmaceutical concentration was removed after 360 min of irradiation and its removal followed a pseudo first order kinetic model with a degradation rate constant of k = 0.00618 min−1. Moreover, scavenging studies indicated that the indirectly produced hydroxy radicals contribute very little to the degradation mechanism. Through high precision mass spectrometry techniques, eight transformation products (TPs) were identified, and possible transformation pathways were suggested. Similarly, in the case of pilot scale experiments, 100 and 200 mg L−1 of g-C3N4 were used and the antibiotic’s removal also followed pseudo first order kinetics with k = 0.00827 min−1 and k = 0.00942 min−1, respectively. However, starting from low level inherent concentrations, only two TPs were identified. By using in silico tools (ECOSAR and T.E.S.T.), various ecotoxicological values were predicted for the TPs, which were generally found to be less toxic than the parent compound and with lower mutagenic and bioaccumulative potential. Moreover, the monitoring of the ecotoxicity with the in vitro Microtox bioassay showed that at the end of all the photocatalytic processes, the toxicity was reduced. In conclusion, this technique could have the potential to remove MTZ and other similar pharmaceuticals in full-scale applications. However, for this to happen with the highest possible efficiency, further studies must be conducted, focusing on improving the catalyst’s performance and reusability, improving the separation of catalyst as well as finding the optimum conditions for this process.

Examination of the accuracy of SHRIMP U–Pb geochronology based on samples dated by both SHRIMP and CA-TIMS

Abstract. Estimations of the reproducibility of U–Pb ages from SHRIMP (Sensitive High-Resolution Ion MicroProbe) instruments are based on data from studies that are nearly 2 decades old. Since that time, refinement of analytical procedures and operational improvements have reduced the historically identified uncertainties of SHRIMP U–Pb analysis. This paper investigates 36 SHRIMP thermal ionisation mass spectrometry (TIMS) double-dated “real-world” geologic samples from a variety of igneous rock types to better understand both geological and analytical sources of disagreement between the two dating methods. Geoscience Australia's (GA) use of high-precision chemical abrasion thermal ionisation mass spectrometry (CA-TIMS) for chronostratigraphy in Australian sedimentary basins has produced a substantial selection of precisely dated zircons, which we can use to cross-correlate the SHRIMP and CA-TIMS ages throughout the Phanerozoic. A total of 33 of the 36 ages were reported with external SHRIMP uncertainties less than 1 % (95 % confidence). Six of eight cases where the CA-TIMS age was outside the SHRIMP uncertainty envelope were in samples where the 95 % confidence interval of the reported SHRIMP age was below 0.66 % uncertainty, suggesting that SHRIMP analyses of untreated zircon with smaller uncertainties are probably overoptimistic. The mean age offset between SHRIMP and TIMS ages is 0.095 %, but the distribution appears bimodal. Geological explanations for age discrepancies between SHRIMP and CA-TIMS are suggested by considering intrusive and extrusive age results separately. All but one sample where the SHRIMP age is more than 0.25 % older are volcanic. This offset could be explained by the better single-grain age resolution of TIMS, allowing identification and exclusion of antecrysts from the eruptive population, while SHRIMP does not have a sufficient single-grain precision to deconvolve these populations – leading to an apparent older SHRIMP age. In contrast, SHRIMP ages from plutonic rocks – particularly plutonic rocks from the early Paleozoic – are typically younger than the CA-TIMS ages from the same samples, most likely reflecting Pb loss from non-chemically abraded SHRIMP zircons, while chemical abrasion of zircons prior to TIMS analysis destroyed or corrected these areas of Pb loss.

Bile proteome analysis by high-precision mass spectrometry to examine novel biomarkers of primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of unknown etiology that affects the intra- and extrahepatic bile ducts. The present study examined the utility of a bile proteome analysis using a high-sensitivity mass spectrometer to comprehensively screen for novel PSC biomarkers. Bile endoscopically collected from patients with PSC, common bile duct stones, and biliary tract cancer were subjected to high-precision liquid chromatography/mass spectrometry. Some of the proteins specifically up-regulated in the bile of the PSC group were re-examined by an enzyme-linked immunosorbent assay. A total of 8094 proteins were successfully identified and 332 were specifically up-regulated in the PSC group. The bioinformatics analysis showed that proteins involved in the proliferation and activation of diverse inflammatory cells were up-regulated in the PSC group. A receiver operating characteristic curve analysis showed good area under the curve values for interleukin-8 and annexin A1 (ANXA1) (0.836 and 0.914, respectively). Immunostaining for ANXA1 revealed its strong expression in inflammatory cells infiltrating the peripheral biliary tract in PSC livers. A bile proteome analysis is a useful tool for elucidating the pathogenesis of PSC and developing new diagnostic approaches. Therefore, ANXA1 has potential as a bile biomarker for PSC.

Precise zircon U-Pb dating of the Mesoproterozoic Gawler large igneous province, South Australia

The Mesoproterozoic Gawler Range Volcanics and Benagerie Volcanic Suite of the Gawler Craton and Curnamona Province, South Australia, together with associated intrusive magmatism, define an intracontinental, subaerial large igneous province (LIP) preserving an estimated 110 000 km3 of volcanic rock, which hosts one of the world's largest orebodies, the Fe oxide-Cu-Au-U deposit at Olympic Dam, and numerous other related Cu-Au deposits. New high-precision Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-TIMS) U-Pb dates on volcanic zircons allow for regional correlations between stratigraphic units of the GRV and BVS, and an understanding of how magmatic styles, temperatures, composition and mantle source input evolve over the duration of the LIP. The new dates indicate that the entire volcanic province erupted over a geologically short time interval of less than 10 million years, from c. 1595 to 1586 Ma, culminating in a widespread, voluminous flood rhyolite province that erupted in less than 1.5 million years, and most likely in 260,000 years or less. This follows a pattern of volcanism that is similar in duration and volume to mafic and bimodal continental LIPs, of which the mafic-dominated Phanerozoic continental flood basalt provinces are the more common end member.

Direct high-precision mass spectrometry of superheavy elements with SHIPTRAP

Direct mass measurements in the region of the heaviest elements were performed with the Penning-trap mass spectrometer SHIPTRAP at GSI Darmstadt. Utilizing the phase-imaging ion-cyclotron-resonance mass-spectrometry technique, the atomic masses of No251 (Z=102), Lr254 (Z=103), and Rf257 (Z=104) available at rates down to one detected ion per day were determined directly for the first time. The ground-state masses of No254 and Lr255,256 were improved by more than one order of magnitude. Relative statistical uncertainties as low as δm/m≈10−9 were achieved. Mass resolving powers of 11 000 000 allowed resolving long-lived low-lying isomeric states from their respective ground states in No251,254 and Lr254,255. This provided an unambiguous determination of the binding energies for odd-A and odd-odd nuclides previously determined only indirectly from decay spectroscopy.Received 24 June 2022Accepted 28 September 2022DOI:https://doi.org/10.1103/PhysRevC.106.054325Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBinding energy & massesNuclear structure & decaysPropertiesA ≥ 220TechniquesMass spectrometryPenning trapsRadioactive beamsNuclear Physics

High-Precision Geochronology of the Xiaojiayingzi Mo Skarn Deposit: Implications for Prolonged and Episodic Hydrothermal Pulses

Abstract The timescales and duration of ore-forming processes in skarn systems are not well constrained. To better understand this, we present high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb zircon and isotope dilution-negative-thermal ionization mass spectrometry (ID-N-TIMS) Re-Os molybdenite geochronology of the Xiaojiayingzi Mo skarn deposit (0.13 Mt Mo at 0.22 wt %), northeastern China. The Xiaojiayingzi deposit is related to an intrusive complex composed of gabbroic diorite, monzodiorite, and granite porphyry. Molybdenite mineralization occurred in two ore blocks, Xiaojiayingzi (0.11 Mt Mo) and Kangzhangzi (0.02 Mt Mo). In the Kangzhangzi ore block, Mo mineralization is concentrated in skarn adjacent to a deep-seated granite porphyry, with minor disseminated and quartz veinlet mineralization within the granite porphyry. In contrast, economic Mo mineralization in the Xiaojiayingzi ore block is concentrated in skarns located between the contact of steeply dipping monzodiorite and the Mesoproterozoic Wumishan Formation, with minor Mo mineralization found in quartz and endoskarn veins hosted in the monzodiorite. Skarn mineralization in both ore blocks converges downward into the mineralized granite porphyry. In the Kangzhangzi ore block, skarn is zoned from deep proximal dark red-brown garnet to shallow distal dark-green pyroxene. In the Xiaojiayingzi ore block, proximal skarn is garnet rich, whereas pyroxene increases away from the monzodiorite-Wumishan Formation contact. In addition, pyroxene becomes more Fe and Mn rich with distance from the intrusions; Pb, Zn, and Ag increase toward the top of the system; and Mo and Fe increase with depth. High-precision CA-ID-TIMS U-Pb zircon geochronology indicates the gabbroic diorite crystallized at 165.359 ± 0.028/0.052/0.18 Ma (uncertainties presented as analytical/+ tracer/+ decay constant uncertainties), with subsequent crystallization of the monzodiorite and granite porphyry at 165.361 ± 0.040/0.059/0.19 and 165.099 ± 0.026/0.051/0.18 Ma, respectively. High-precision ID-N-TIMS Re-Os molybdenite geochronology indicates molybdenite mineralization at Xiaojiayingzi occurred in at least three discrete magmatic-hydrothermal pulses (nominally between 165.48 ± 0.09–165.03 ± 0.13, 163.73 ± 0.09, and 163.11 ± 0.11 Ma). The first episode of molybdenite mineralization formed in exoskarns, endoskarns, and quartz veins and had a minimum duration of 450 ± 40 k.y., between 165.48 ± 0.09/0.68/0.85 and 165.03 ± 0.13/0.67/0.85 Ma. It is likely that skarn ore represents a composite series of mineralization events, more than the three events capable of identification within analytical uncertainty of these high-precision data. Finally, Re-Os dating of quartz Mo veins cutting the monzodiorite and granite porphyry indicates that some mineralization postdated the observed intrusions, between 163.73 ± 0.09/0.70/0.86 and 163.11 ± 0.11/0.70/0.86 Ma, interpreted to be the result of deeper, unobserved intrusions. Collectively, these ages indicate that protracted, pulsed Mo mineralization at the Xiaojiayingzi deposit occurred over a period of at least 2.4 m.y. These data suggest that individual magmatic and/or skarn garnet ages may significantly underestimate the full duration of mineralization. In addition, this study highlights that systematically identifying skarn deposits associated with multiphase intrusive systems may reveal targets for future exploration, as it may point to previously undiscovered mineral resources.

Collision-Induced Dissociation at TRIUMF's Ion Trap for Atomic and Nuclear science

The performance of high-precision mass spectrometry of radioactive isotopes can often be hindered by large amounts of contamination, including molecular species, stemming from the production of the radioactive beam. In this paper, we report on the development of Collision-Induced Dissociation (CID) as a means of background reduction for experiments at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). This study was conducted to characterize the quality and purity of radioactive ion beams and the reduction of molecular contaminants to allow for mass measurements of radioactive isotopes to be done further from nuclear stability. This is the first demonstration of CID at an ISOL-type radioactive ion beam facility, and it is shown that molecular contamination can be reduced up to an order of magnitude.

Features of steroidogenesis in men with hypogonadism and type 2 diabetes

Type 2 diabetes mellitus (DM2) in men is associated with a high incidence of hypogonadism. Testosterone is a steroid hormone and one of the final metabolites of steroidogenesis, which causes interest in assessing the content of key steroid hormones, their precursors and metabolites in hypogonadal and eugonadal men with T2DM. Assessment of the features of steroidogenesis in men with hypogonadism in T2DM using tandem mass spectrometry. A full-design, cross-sectional, screening, single-center, non-interventional study included men with T2DM, who were he was treated in Endocrinology Research Centre, Moscow. The study was conducted from October 2021 to January 2022. Medical history assessment, physical examination with determination of body mass index (BMI), measurement of key steroid hormones, their precursors and metabolites by isotope dilution liquid chromatography/tandem mass spectrometry, glycated hemoglobin (HbA1c) were performed. The groups were compared using the Mann-Whitney U-test for quantitative indicators and χ² with Yates' correction for qualitative ones. Correlation analysis was performed by the Spearman correlation method. When determining the criterion of statistical significance, the Bonferroni correction was applied. Patients with hypogonadism had statistically significantly more pronounced obesity compared with eugonadal men. In a comparative analysis of patients, depending on the presence of hypogonadism, there were statistically significantly lower levels of androgen precursors 17-hydroxypregnenolone and 17-hydroxyprogesterone in hypogonadal men. At thesame time, a positive statistically significant correlation was found between total testosterone and 17-hydroxyprogesterone. In addition, 17-hydroxyprogesterone, although to a lesser extent, but positively correlated with other androgens- androstenedione (r=0,328; p&lt;0,001) and dehydroepiandrosterone (r=0,183; p=0,004). &gt;&lt; 0,001) and dehydroepiandrosterone (r=0,183; p=0,004). In this investigation the prevalence of male hypogonadism in type 2 diabetes, determined by high-precision tandem mass spectrometry, was 69,5%. There was no effect of the disease on the mineralocorticoid and glucocorticoid links of adrenal steroidogenesis. Hypogonadism was associated with decreased levels of a number of testosterone precursors. Themost significant of them was 17-hydroxyprogesterone, which can be considered as a marker of testicular steroidogenesis.

The importance of high precision in the evaluation of U-Pb zircon age spectra

We present high-precision isotope dilution-thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon data from the Carboniferous Punteglias granodiorite from the Central Alpine basement in the Aar massif in Switzerland. These analyses yield complex age spectra consisting of both concordant and normally discordant dates, which form a linear array indicative of mixing of two age components within individual zircon crystals. While the upper intercept age reflects zircon growth during Variscan magmatism, the lower intercept of 24 ± 11 Ma is coincident with the Alpine orogeny. There is poor evidence from cathodo-luminescence imagery that magmatic zircon may have younger overgrowths, therefore, we pretreated an aliquot of zircon with physical abrasion followed by chemical abrasion to remove any potential later zircon overgrowths, and to directly date the initial magmatic domains of the zircon. This pretreatment significantly reduced age dispersion and yielded an age of 335.479 ± 0.041 Ma for the crystallization of zircon in the Punteglias granodiorite. Due to the effectiveness of this pretreatment, we interpret that the magmatic zircon was overgrown with younger domains during the Alpine orogeny. Detangling the observed complications in the Punteglias granodiorite zircons was largely possible due to the particularly high analytical precision of the ID-TIMS U-Pb dates that made it possible to detect discordance between the 206Pb/238U and 207Pb/235U systems. Lower-precision U-Pb ID-TIMS dates would not allow identification of such a two-component mixture and lead to analytically concordant points spreading over 105 to 106 years, and potentially leading to erroneous scientific interpretation. As an example, we model two hypothetical situations of simple mixing of two age components in the U-Pb concordia space to demonstrate the effect of precision on the ability to accurately interpret geological models from complicated age spectra. Combining these new high-precision data and modeling results highlights the importance of choosing the optimal, physical and/or chemical sample pre-treatment and the challenge of accurately interpreting complicated U-Pb data in terms of crystallization age.

Increasing atmospheric helium due to fossil fuel exploitation

Fossil fuels contain small amounts of helium, which are co-released into the atmosphere together with carbon dioxide. However, a clear build-up of helium in the atmosphere has not previously been detected. Using a high-precision mass spectrometry technique to determine the atmospheric ratio of helium-4 to nitrogen, we show that helium-4 concentrations have increased significantly over the past five decades. Obtaining a direct measure of the rise in atmospheric helium-4 is possible because changes in nitrogen are negligible. Using 46 air samples acquired between 1974 and 2020, we find that the helium-4 concentration increased at an average rate of 39 ± 3 billion mol per year (2σ). Given that previous observations have shown that the ratio between helium-3 and helium-4 in the atmosphere has remained constant, our results also imply that the concentration of helium-3 is increasing. The inferred rise in atmospheric helium-3 greatly exceeds estimates of anthropogenic emissions from natural gas, nuclear weapons and nuclear power generation, suggesting potential problems with previous isotope measurements or an incorrect assessment of known sources. Mass spectrometry measurements show that the concentration of helium in the atmosphere has risen over the past five decades due to fossil fuel emissions.

Precision measurement of the transition energy [formula omitted] versus magnetic rigidity for storage-ring isochronous mass spectrometry

The transition energy, γt, of a heavy-ion storage ring is an important machine parameter. The variation of γt versus the magnetic rigidity, Bρ, over the acceptance of the ring directly affects the mass resolving power achievable in the high-precision isochronous mass spectrometry (IMS). With two time-of-flight (TOF) detectors installed in a straight section of the ring, revolution frequency (revolution time) and velocity of each stored ion can simultaneously be measured. By using these quantities, a method for fast and precise γt determinations has been developed. The dependence of γt on the orbit length (or Bρ) has been obtained. The newly developed method does not require particle identification and is thus suitable for real-time monitoring of the ion optical setting during experiment.

Investigation of the usefulness of bile proteome analysis using high-precision mass spectrometry in the search for novel biomarkers of biliary tract cancer

Investigation of the usefulness of bile proteome analysis using high-precision mass spectrometry in the search for novel biomarkers of biliary tract cancer