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Abstract Hydrogen sulfide (H₂S) and nitric oxide (NO) are important gaseous biological signaling molecules that are involved in complex cellular pathways. A number of physiological processes require both H₂S and NO, which has led to the proposal that different H₂S/NO⋅ crosstalk species, including thionitrite (SNO⁻) and perthionitrite (SSNO⁻), are responsible for this observed codependence. Despite the importance of these S/N hybrid species, the reported properties and characterization, as well as the fundamental pathways of formation and subsequent reactivity, remain poorly understood. Herein we report new experimental insights into the fundamental reaction chemistry of pathways to form SNO⁻and SSNO⁻, including mechanisms for proton‐mediated interconversion. In addition, we demonstrate new modes of reactivity with other sulfur‐containing potential crosstalk species, including carbonyl sulfide (COS). 

Abstract Cucurbit[n]urils (CB[n]s) are cyclic macrocycles with rich host‐guest chemistry. In many cases, guest binding in CB[n]s results in host structural deformations. Unfortunately, measuring such deformations remains a major challenge, with only a handful of manual estimations reported in the literature. To address this challenge, we have developed the public program ElliptiCB[n], which is available on GitHub, that provides a robust and automated method for measuring the elliptical deformations in CB[n] hosts. We outline the development and validation of this approach, apply ElliptiCB[n] to measure the ellipticity of the 1113 available CB[n] structures from the Cambridge Structural Database (CSD), and directly investigate the structural deformations of CB[5], CB[6], CB[7], CB[8], and CB[10] hosts. We also report the general landscape of accessible CB[n] elliptical deformations and compare ellipticity distributions across CB[n] hosts and host‐guest complexes. We found that in almost all cases guest binding significantly impacts the distribution of host ellipticity distributions and that these distributions are dissimilar across host‐guest complexes of differently sized CB[n]s. We anticipate that this work will provide a useful approach for understanding of the flexibility of CB[n] hosts and will also enable future measurement and standardization of ellipticity measurements of CB[n]s. 

Abstract Historically, clumped isotope thermometry (T(∆₄₇)) of soil carbonates has been interpreted to represent a warm‐season soil temperature based dominantly on coarse‐grained soils. Additionally, T(∆₄₇) allows the calculation of the oxygen isotope composition of soil water (δ¹⁸O_w) in the past using the temperature‐dependent fractionation factor between soil water and pedogenic carbonate, but previous work has not measured δ¹⁸O_wvalues with which to compare to these archives. Here, we present clumped isotope thermometry of modern soil carbonates from three soils in Colorado and Nebraska, USA, that have a fine‐to‐medium grain size, contain clay, and are representative of many carbonate‐bearing paleosols preserved in the rock record. At two of the three sites, Briggsdale, CO and Seibert, CO, T(∆₄₇) overlaps with mean annual soil temperature (MAST), and the calculated δ¹⁸O_woverlaps within uncertainty with measured δ¹⁸O_wat carbonate bearing depths. At the third site, in Oglala National Grassland, NE, mean T(∆₄₇) is 8–11°C warmer than MAST, and the calculated δ¹⁸O_whas a significantly higher isotope value than any observations of δ¹⁸O_w. At all three sites, even in the fall season, δ¹⁸O_wvalues at carbonate bearing depths overlap with spring rainfall δ¹⁸O_w, and there is little to no evaporative enrichment of δ²H_wand δ¹⁸O_wvalues. These data challenge long‐held assumptions that all pedogenic carbonate records a warm‐season bias, and that δ¹⁸O_wat carbonate‐bearing depths is affected by evaporative enrichment. 

Abstract Mechanically interlocked molecules (MIMs) represent an exciting yet underexplored area of research in the context of carbon nanoscience. Recently, work from our group and others has shown that small carbon nanotube fragments—[n]cycloparaphenylenes ([n]CPPs) and related nanohoop macrocycles—may be integrated into mechanically interlocked architectures by leveraging supramolecular interactions, covalent tethers, or metal‐ion templates. Still, available synthetic methods are typically difficult and low yielding, and general methods that allow for the creation of a wide variety of these structures are limited. Here we report an efficient route to interlocked nanohoop structures via the active template Cu‐catalyzed azide‐alkyne cycloaddition (AT−CuAAC) reaction. With the appropriate choice of substituents, a macrocyclic precursor to 2,2′‐bipyridyl embedded [9]CPP (bipy[9]CPP) participates in the AT−CuAAC reaction to provide [2]rotaxanes in near‐quantitative yield, which can then be converted into the fully π‐conjugated catenane structures. Through this approach, two nanohoop[2]catenanes are synthesized which consist of a bipy[9]CPP catenated with either Tz[10]CPP or Tz[12]CPP (whereTzdenotes a 1,2,3‐triazole moiety replacing one phenylene ring in the [n]CPP backbone). 

Abstract Atmospheric rivers (ARs) are long, narrow regions of water vapor in the Earth's atmosphere that transport heat and moisture from the tropics to the mid‐latitudes. ARs are often associated with extreme weather events in North America and contribute significantly to water supply and flood risk. However, characterizing ARs has been a major challenge due to the lack of a universal definition and their structural variations. Existing AR detection tools (ARDTs) produce distinct AR boundaries for the same event, making the risk assessment of ARs a difficult task. Understanding these uncertainties is crucial to improving the predictability of AR impacts, including their landfall areas and associated precipitation, which could cause catastrophic flooding and landslides over the coastal regions. In this work, we develop an uncertainty visualization framework that captures boundary and interior uncertainties, i.e., structural variations, of an ensemble of ARs that arise from a set of ARDTs. We first provide a statistical overview of the AR boundaries using the contour boxplots of Whitaker et al. that highlight the structural variations of AR boundaries based on their nesting relationships. We then introduce the topological skeletons of ARs based on Morse complexes that characterize the interior variation of an ensemble of ARs. We propose an uncertainty visualization of these topological skeletons, inspired by MetroSets of Jacobson et al. that emphasizes the agreements and disagreements across the ensemble members. Through case studies and expert feedback, we demonstrate that the two approaches complement each other, and together they could facilitate an effective comparative analysis process and provide a more confident outlook on an AR's shape, area, and onshore impact. 

Abstract Eddy covariance (EC) air–sea CO₂flux measurements have been developed for large research vessels, but have yet to be demonstrated for smaller platforms. Our goal was to design and build a complete EC CO₂flux package suitable for unattended operation on a buoy. Published state-of-the-art techniques that have proven effective on research vessels, such as airstream drying and liquid water rejection, were adapted for a 2-m discus buoy with limited power. Fast-response atmospheric CO₂concentration was measured using both an off-the-shelf (“stock”) gas analyzer (EC155, Campbell Scientific, Inc.) and a prototype gas analyzer (“proto”) with reduced motion-induced error that was designed and built in collaboration with an instrument manufacturer. The system was tested on the University of New Hampshire (UNH) air–sea interaction buoy for 18 days in the Gulf of Maine in October 2020. The data demonstrate the overall robustness of the system. Empirical postprocessing techniques previously used on ship-based measurements to address motion sensitivity of CO₂analyzers were generally not effective for the stock sensor. The proto analyzer markedly outperformed the stock unit and did not require ad hoc motion corrections, yet revealed some remaining artifacts to be addressed in future designs. Additional system refinements to further reduce power demands and increase unattended deployment duration are described. 

Data associated with Figures, Tables, and population parameter samples associated with  The population of merging compact binaries inferred using gravitational waves through GWTC-3 , </strong> LIGO DCC, arXiv, PRX. </strong> This is v2, superseding v1. Please see the README.md for more information.</p> LIGO Laboratory and Advanced LIGO are funded by the United States National Science Foundation (NSF) as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society (MPS), and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory (EGO), by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN) and the Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan, Monaco, Poland, Portugal, Spain. The construction and operation of KAGRA are funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT), and Japan Society for the Promotion of Science (JSPS), National Research Foundation (NRF) and Ministry of Science and ICT (MSIT) in Korea, Academia Sinica (AS) and the Ministry of Science and Technology (MoST) in Taiwan.