Determination of Osmium Concentration and Isotope Composition at Ultra-low Level in Polar Ice and Snow

Here we use two chemical separation procedures to determine exceptionally low Os concentrations (∼10^–15 g g^–1) and Os isotopic composition in polar snow/ice. Approximately 50 g of meltwater is spiked with ¹⁹⁰Os tracer solution and frozen at −20 °C in quartz-glass ampules. A mixture of H₂O₂ and HNO₃ is then added, and the sample is heated to 300 °C at 100 bar. This allows tracer Os to be equilibrated with the sample as all Os species are oxidized to OsO₄. The resulting OsO₄ is separated using either distillation (Method-I) or solvent-extraction (Method-II), purified, and measured using negative thermal ionization mass spectrometry (N-TIMS). A new technique is presented that minimizes Re and Os blanks of the Pt filaments used in N-TIMS. We analyze snow collected from Summit, Greenland during 2009, 2014, and 2017. We find that the average Os concentration of the snow is 0.459 ± 0.018 (95% C.I.) fg g^–1 corresponding to an Os flux of 0.0579 ± 0.0023 (95% C.I.) fmol cm^–2 yr^–1. The average <i>R</i>(¹⁸⁷Os/¹⁸⁸Os) ratio of the Summit snow is 0.264 ± 0.026 (95% C.I.). Assuming that the volcanic source is negligible, the average ratio indicates that about 0.0518 ± 0.0040 (95% C.I.) fmol cm^–2 yr^–1 of Os is of cosmic derivation, corresponding to an accretion rate of extra-terrestrial Os to the Earth of 264 ± 21 mol yr^–1

²³⁸U/²³⁵U isotope ratios of crustal material, rivers and products of hydrothermal alteration: new insights on the oceanic U isotope mass balance

<p>In this study, the U isotope composition, <i>n</i>(²³⁸U)/<i>n</i>(²³⁵U), of major components of the upper continental crust, including granitic rocks of different age and post-Archaean shales, as well as that of rivers (the major U source to the oceans) was investigated. Furthermore, U isotope fractionation during the removal of U at mid-ocean ridges, an important sink for U from the oceans, was investigated by the analyses of hydrothermal water samples (including low- and high-temperature fluids), low-temperature altered basalts and calcium carbonate veins. All analysed rock samples from the continental crust fall into a limited range of δ²³⁸U between −0.45 and −0.21 ‰ (relative to NBL CRM 112-A), with an average of −0.30 ± 0.15 ‰ (2 SD, <i>N</i> = 11). Despite differences in catchment lithologies, all major rivers define a relatively narrow range between −0.31 and −0.13 ‰, with a weighted mean isotope composition of −0.27 ‰, which is indistinguishable from the estimate for the upper continental crust (−0.30 ‰). Only some tributary rivers from the Swiss Alps display a slightly larger range in δ²³⁸U (−0.29 to +0.01 ‰) and lower U concentrations (0.87–3.08 nmol/kg) compared to the investigated major rivers (5.19–11.69 nmol/kg). These findings indicate that only minor net U isotope fractionation occurs during weathering and transport of material from the continental crust to the oceans. Altered basalts display moderately enriched U concentrations (by a factor of 3–18) compared to those typically observed for normal mid-ocean ridge basalts. These, and carbonate veins within altered basalts, show large U isotope fractionation towards both heavy and light U isotope compositions (ranging from −0.63 to +0.27 ‰). Hydrothermal water samples display low U concentrations (0.3–1 nmol/kg) and only limited variations in their U isotope composition (−0.43 ± 0.25 ‰) around the seawater value. Nevertheless, two of the investigated fluids display significantly lower δ²³⁸U (−0.55 and −0.59 ‰) than seawater (−0.38 ‰). These findings, together with the heavier U isotope composition observed for some altered basalts and carbonate veins support a model, in which redox processes mostly drive U isotope fractionation. This may result in a slightly heavier U isotope composition of U that is removed from seawater during hydrothermal seafloor alteration compared to that of seawater. Using the estimated isotope compositions of rivers and all U sinks from the ocean (of this study and the literature) for modelling of the isotopic U mass balance, this gives reasonable results for recent estimates of the oceanic U budget. It furthermore provides additional constraints on the relative size of the diverse U sinks and respective net isotope fractionation during U removal.</p

QuitPilot_Participants sp

This data set includes characteristics of study participants including demographic and smoking history. It also include 6-month study outcomes for smoking abstinence, quit attempts, current number of cigarettes, adherence to counselling and medication

sj-docx-1-eso-10.1177_23969873221139410 – Supplemental material for Prolonged cardiac monitoring for stroke prevention: A systematic review and meta-analysis of randomized-controlled clinical trials

Supplemental material, sj-docx-1-eso-10.1177_23969873221139410 for Prolonged cardiac monitoring for stroke prevention: A systematic review and meta-analysis of randomized-controlled clinical trials by Georgios Tsivgoulis, Lina Palaiodimou, Sokratis Triantafyllou, Martin Köhrmann, Polychronis Dilaveris, Konstantinos Tsioufis, Gkikas Magiorkinis, Christos Krogias, Peter D Schellinger, Valeria Caso, Maurizio Paciaroni, Mukul Sharma, Robin Lemmens, David J Gladstone, Tommaso Sanna, Rolf Wachter, Gerasimos Filippatos and Aristeidis H Katsanos in European Stroke Journal</p

Supplemental material for Canadian Stroke Best Practice Consensus Statement: <i>Acute Stroke Management during pregnancy</i>

<p>Supplemental material for Canadian Stroke Best Practice Consensus Statement: <i>Acute Stroke Management during pregnancy</i> by Noor Niyar N Ladhani, Richard H Swartz, Norine Foley, Kara Nerenberg, Eric E Smith, Gord Gubitz, Dariush Dowlatshahi, Jayson Potts, Joel G Ray, Jon Barrett, Cheryl Bushnell, Simerpreet Bal, Wee-Shian Chan, Radha Chari, Meryem El Amrani, Shital Gandhi, Michael D Hill, Andra James, Thomas Jeerakathil, Albert Jin, Adam Kirton, Sylvain Lanthier, Andrea Lausman, Lisa Rae Leffert, Jennifer Mandzia, Bijoy Menon, Aleksandra Pikula, Alexandre Poppe, Gustavo Saposnik, Mukul Sharma, Sanjit Bhogal, Elisabeth Smitko and M Patrice Lindsay; on behalf of the Heart and Stroke Foundation Canadian Stroke Best Practice and Quality Advisory Committees; in collaboration with the Canadian Stroke Consortium in International Journal of Stroke</p

Supplemental material 1 for Rationale, design, and baseline participant characteristics in the MRI and cognitive substudy of the cardiovascular outcomes for people using anticoagulation strategies trial

<p>Supplemental material 1 for Rationale, design, and baseline participant characteristics in the MRI and cognitive substudy of the cardiovascular outcomes for people using anticoagulation strategies trial by Mukul Sharma, Robert G Hart, Eric E Smith, Jackie Bosch, Fei Yuan, Amparo Casanova, John W Eikelboom, Stuart J Connolly, Gloria Wong, Rafael Diaz, Patricio Lopez-Jaramillo, Georg Ertl, Stefan Störk, Gilles R Dagenais, Eva M Lonn, Lars Ryden, Andrew M Tonkin, John D Varigos, Deepak L Bhatt, Kelley RH Branch, Jeffrey L Probstfield, Jae-Hyung Kim, Jong-Won Ha, Martin O’Donnell, Dragos Vinereanu, Keith AA Fox, Yan Liang, Lisheng Liu, Jun Zhu, Nana Pogosova, Aldo P Maggioni, Alvaro Avezum, Leopoldo S Piegas, Katalin Keltai, Matyas Keltai, Nancy Cook Bruns, Scott Berkowitz and Salim Yusuf in International Journal of Stroke</p