bluuebunny/crossref_metadata_2025_split huggingface dataset:
Constraining the Location of the Outer Boundary of Earth's Outer Radiation Belt
Authors: Bloch T. , Watt C. E. J. , Owens M. J. , Thompson R. L. , Agiwal O. 
Published: May 2021

AbstractCharacterizing the location of the outer boundary of the outer radiation belt is a key aspect of improving radiation belt models and helps to constrain our understanding of the mechanisms by which the source and seed electron populations are transported into the radiation belts. In this paper, we hypothesize that there are statistical differences in the electron distribution function across the radiation belt outer boundary, and thus analyze electron flux data from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) satellites to identify this location. We validate our hypothesis by using modeled electron L* values to approximately characterize the differences between electron distribution functions inside and outside of the radiation belts. Initially, we perform a simple statistical analysis by studying the radial evolution of the electron distribution functions. This approach does not yield a clear discontinuity, thus highlighting the need for more complex statistical treatment of the data. Subsequently, we employ machine learning (with no dependence on radial position or L*) to test a range of candidate outer boundary locations. By analyzing the performance of the models at each candidate location, we identify a statistical boundary at ≈8 RE, with results suggesting some variability. This statistical boundary is typically further out than those used in current radiation belt models.
Temporal Variability of Air‐Sea CO2 flux in the Western Tropical North Atlantic Influenced by the Amazon River Plume
Authors: Mu Linquan , Gomes Helga do Rosario , Burns Shannon M. , Goes Joaquim I. , Coles Victoria J. , Rezende Carlos E. , Thompson Fabiano L. , Moura Rodrigo L. , Page Benjamin , Yager Patricia L. 
Published: May 2021

AbstractThe partial pressure of carbon dioxide (pCO2) was surveyed across the Amazon River plume and the surrounding western tropical North Atlantic Ocean (15–0°N, 43–60°W) during three oceanic expeditions (May–June 2010, September–October 2011, and July 2012). The survey timing was chosen according to previously described temporal variability in plume behavior due to changing river discharge and winds. In situ sea surface pCO2 and air‐sea CO2 flux exhibited robust linear relationships with sea surface salinity (SSS; 15 < SSS < 35), although the relationships differed among the surveys. Regional distributions of pCO2 and CO2 flux were estimated using SSS maps from high‐resolution ocean color satellite‐derived (MODIS‐Aqua) diffuse attenuation coefficient at 490 nm (Kd490) during the periods of study. Results confirmed that the plume is a net CO2 sink with distinctive temporal variability: the strongest drawdown occurred during the spring flood (−2.39 ± 1.29 mmol m−2 d−1 in June 2010), while moderate drawdown with relatively greater spatial variability was observed during the transitional stages of declining river discharge (−0.42 ± 0.76 mmol m−2 d−1 in September–October 2011). The region turned into a weak source in July 2012 (0.26 ± 0.62 mmol m−2 d−1) when strong CO2 uptake in the mid‐plume was overwhelmed by weak CO2 outgassing over a larger area in the outer plume. Outgassing near the mouth of the river was observed in July 2012. Our observations draw attention to the importance of assessing the variable impacts of biological activity, export, and air‐sea gas exchange before estimating regional CO2 fluxes from salinity distributions alone.
Climatic and Landscape Controls on Long‐Term Baseflow
Authors: Yao Lili , Sankarasubramanian A. , Wang Dingbao 
Published: May 2021

AbstractFor evaluating the climatic and landscape controls on long‐term baseflow, baseflow index (BFI, defined as the ratio of baseflow to streamflow) and baseflow coefficient (BFC, defined as the ratio of baseflow to precipitation) are formulated as functions of climate aridity index, storage capacity index (defined as the ratio of average soil water storage capacity to precipitation), and a shape parameter for the spatial variability of storage capacity. The derivation is based on the two‐stage partitioning framework and a cumulative distribution function for storage capacity. Storage capacity has a larger impact on BFI than on BFC. When storage capacity index is smaller than 1, BFI is less sensitive to storage capacity index in arid regions compared to that in humid regions; whereas, when storage capacity index is larger than 1, BFI is less sensitive to storage capacity index in humid regions. The impact of storage capacity index on BFC is only significant in humid regions. The shape parameter plays an important role on fast flow generation at the first‐stage partitioning in humid regions and baseflow generation at the second‐stage partitioning in arid regions. The derived formulae were applied to more than 400 catchments where storage capacity index was found to follow a logarithmic function with climate aridity index. The role of climate forcings at finer timescales on baseflow were quantified, indicating that seasonality in climate forcings has a significant control especially on BFI.
Weakening of Polar Mesosphere Winter Echo and Turbulent Energy Dissipation Rates After a Stratospheric Sudden Warming in the Southern Hemisphere in 2019
Authors: Kohma M. , Sato K. , Nishimura K. , Tsutsumi M. 
Published: May 2021

AbstractTime variations in the polar mesosphere winter echo (PMWE) volume reflectivity and turbulent energy dissipation rates are examined during the sudden stratospheric warming (SSW) in September 2019 in the Southern Hemisphere. It was found that the frequency of PMWE occurrence decreased from early September to October, when the SSW occurred. We also found that the frequency of large turbulent energy dissipation rates (>3 × 10−4 m2s−3) was reduced compared to the average for 2016–2018. This is likely due to the modulation of gravity wave (GW) propagation by the minor SSW, resulting in less GW breaking, which is the main source of the turbulence. This suggests that the decrease in turbulence intensity is at least partly responsible for the decrease in the frequency of PMWE.
The Proliferation of Induced Seismicity in the Permian Basin, Texas
Authors: Skoumal Robert J. , Trugman Daniel T. 
Published: May 2021

AbstractThe Permian Basin has a long history of induced earthquakes, but the seismicity rates have increased dramatically over the past two decades and included a MW 5.0 likely induced by wastewater disposal (WD) in March 2020. A detailed characterization of the proliferation of seismicity in the Permian Basin throughout this time period is needed for improving the scientific understanding of the mechanisms responsible and for mitigating future seismic hazard. Due to a sparse regional seismic network before the advent of Texas Seismological Network in 2017, we characterize seismicity using the 10‐station TXAR array that is 100s of km away from most of the seismicity, with the objective of improving upon the substantial contributions from previous work. By exploiting the nature of waveform similarity, we detect events with template matching, performing a quantitative analysis of spatially varying detection capabilities throughout the study area. From an initial catalog of 10,753 events, we identify 45,009 earthquakes and 10,208 quarry blasts. Using our catalog of earthquakes, we improve epicentral locations, compare relative magnitude techniques, and associate earthquakes to WD or hydraulic stimulations. We further use our earthquake catalog to investigate the relationship between seismicity and human activities near the city of Pecos, Texas. Through a comparison of our earthquake catalog with industrial records, we determine that the vast majority seismicity near Pecos, Texas, since 2000 is likely induced by an increase of WD at wells injecting at depths greater than 1.5 km.
Complex Source Behaviors and Spatiotemporal Evolution of Seismicity During the 2015–2016 Earthquake Sequence in Cushing, Oklahoma
Authors: Meng Qingjun , Ni Sidao , Peng Zhigang 
Published: May 2021

AbstractIn September and October 2015, three M4+ earthquakes occurred as a sequence along a fault northwest of the Cushing city, Oklahoma, followed by another M5 earthquake in November 2016. While previous studies have shown that moderate‐size earthquakes in Oklahoma are likely induced by wastewater injections, it is still not clear what controls the rupture process and spatiotemporal evolutions of seismicity during individual sequences. In this study, we investigated the rupture process of these four M4‐5 events in 2015–2016 with finite fault model (FFM) inversions, and computed the static stress changes during this sequence. We found that the rupture processes of four M4‐5 earthquakes were very complex, and each of them had several subevents with different rupture directivities. The 2016 M5 earthquake started near the region where three M4+ events initiated, but the majority of the slip occurred a few kilometers away in the northeast direction. In comparison, the 2015 M4.3 event mainly ruptured toward the southwest direction. Due to data limitation and inversion uncertainties, we were unable to constrain the rupture directivities for the other two M4+ events. The foreshocks 3 days before the first M4+ earthquake in 2015 occurred in a region of positive shear stress changes caused by previous earthquakes in 2014–2015 on unmapped faults several kilometers to the south. Our results suggest small‐scale heterogeneity in controlling complex seismicity and rupture patterns in the 2015–2016 Cushing sequence, and possible triggering of this sequence by a small stress perturbation on order of a few kilopascals.
Evolutionary computing and machine learning for discovering of low-energy defect configurations
Authors: Arrigoni Marco , Madsen Georg K. H. 
Published: May 2021

AbstractDensity functional theory (DFT) has become a standard tool for the study of point defects in materials. However, finding the most stable defective structures remains a very challenging task as it involves the solution of a multimodal optimization problem with a high-dimensional objective function. Hitherto, the approaches most commonly used to tackle this problem have been mostly empirical, heuristic, and/or based on domain knowledge. In this contribution, we describe an approach for exploring the potential energy surface (PES) based on the covariance matrix adaptation evolution strategy (CMA-ES) and supervised and unsupervised machine learning models. The resulting algorithm depends only on a limited set of physically interpretable hyperparameters and the approach offers a systematic way for finding low-energy configurations of isolated point defects in solids. We demonstrate its applicability on different systems and show its ability to find known low-energy structures and discover additional ones as well.
Influence of accessory phases and surrogate type on accelerated leaching of zirconolite wasteforms
Authors: Blackburn Lewis R. , Crawford Rachel , Walling Samuel A. , Gardner Laura J. , Cole Max R. , Sun Shi-Kuan , Gausse Clémence , Mason Amber R. , Stennett Martin C. , Maddrell Ewan R. , Hyatt Neil C. , Corkhill Claire L. 
Published: May 2021

AbstractA fraction of the UK Pu inventory may be immobilised in a zirconolite ceramic matrix prior to disposal. Two zirconolite compositions, targeting CaZr0.80Ce0.20Ti2O7 and CaZr0.80U0.20Ti2O7, were fabricated by hot isostatic pressing, alongside a reformulated composition, nominally Ca0.80Zr0.90Ce0.30Ti1.60Al0.40O7, with an excess of Ti and Zr added to preclude the formation of an accessory perovskite phase. Materials were subjected to accelerated leaching in a variety of acidic and alkaline media at 90 °C, over a cumulative period of 14 d. The greatest Ce release was measured from CaZr0.80Ce0.20Ti2.00O7 exposed to 1 M H2SO4, for which 14.7 ± 0.2% of the original Ce inventory was released from the wasteform into solution. The extent of Ce leaching into the solution was correlated with the quantity of perovskite present in the wasteform, and associated with the incorporation and preferential dissolution of Ce3+. CaZr0.80U0.20Ti2.00O7 exhibited improved leach resistance relative to CaZr0.80Ce0.20Ti2.00O7, attributed to the decreased proportion of accessory perovskite, with 7.1 ± 0.1% U released to in 8 M HNO3 after 7 d. The Ca0.80Zr0.90Ce0.30Ti1.60Al0.40O7 composition, with no accessory perovskite phase, presented significantly improved leaching characteristics, with < 0.4%Ce released in both 8 M HNO3 and 1 M H2SO4. These data demonstrate the need for careful compositional design for zirconolite wasteforms with regard to accessory phase formation and surrogate choice.
Cleavage-dissolution assisted stress corrosion cracking under elastic loads
Authors: Zhu Longkui , Li Yao 
Published: May 2021

AbstractAs a significant cause of disastrous accidents, stress corrosion cracking (SCC) under elastic loads was investigated in type 316 L single-crystal stainless steel immersed in a boiling 45 wt% MgCl2 solution. Three-dimensional microcrack morphologies, characterized using synchrotron-based X-ray computed tomography, indicate that the SCC advanced along the cleavage planes (1 0 0) with the lowest free surface energy. The first-principles simulations show that synergistic adsorption of H and Cl atoms in the octahedral interstices minimized the surface energy of the cleavage planes (0 0 1) owing to a 73% reduction. Afterwards, the cleavage-dissolution mechanism is put forward, proposing that the SCC essentially originates from preferential brittle rupture of the corrosive environment particle adsorbed low-surface-energy cleavage planes in the elastic stress concentration zones, and anodic dissolution along the crack fronts. Besides, the corrosive environment particles primarily consist of the hydrogen atoms and the electronegative ions such as the chlorine ions.
Supramolecular exfoliation of layer silicate clay by novel cationic pillar[5]arene intercalants
Authors: Kakuta Takahiro , Baba Yudai , Yamagishi Tada-aki , Ogoshi Tomoki 
Published: May 2021

AbstractClays are multi-layered inorganic materials that can be used to prepare nanocomposite fillers. Because the multi-layered structure is thermodynamically stable, it is difficult to change a multi-layered material into single layers to improve its dispersity. Previously, clays were modified with dodecylammonium cations to promote complexation with nylon 6, nylon 66, polypropylene, polyethylene, polystyrene, and polycaprolactone to increase the mechanical strength (and/or thermal stability) of the composite material; however, complete exfoliation could not be achieved in these composites. In this study, pillar[5]arenes are synthesized and functionalized with ten cationic substituents as novel intercalants for modifying bentonite clay, which is a multi-layered metal-cation-containing silicate. The pillar[5]arenes exfoliate the clay by forming polyrotaxanes with poly(ethylene glycol) through host–guest interactions.
Predictive value of pre-arrest albumin level with GO-FAR score in patients with in-hospital cardiac arrest
Authors: Hong Seok-In , Kim Youn-Jung , Cho Yeon Joo , Huh Jin Won , Hong Sang-Bum , Kim Won Young 
Published: May 2021

AbstractWe investigated whether combining the pre-arrest serum albumin level could improve the performance of the Good Outcome Following Attempted Resuscitation (GO-FAR) score for predicting neurologic outcomes in in-hospital cardiac arrest patients. Adult patients who were admitted to a tertiary care hospital between 2013 and 2017 were assessed. Their pre-arrest serum albumin levels were measured within 24 h before the cardiac arrest. According to albumin levels, the patients were divided into quartiles and were assigned 1, 0, 0, and, − 2 points. Patients were allocated to the derivation (n = 419) and validation (n = 444) cohorts. The proportion of favorable outcome increased in a stepwise manner across increasing quartiles (p for trend < 0.018). Area under receiver operating characteristic curve (AUROC) of the albumin-added model was significantly higher than that of the original GO-FAR model (0.848 vs. 0.839; p = 0.033). The results were consistent in the validation cohort (AUROC 0.799 vs. 0.791; p = 0.034). Net reclassification indices of the albumin-added model were 0.059 (95% confidence interval [CI] − 0.037 to 0.094) and 0.072 (95% CI 0.013–0.132) in the derivation and validation cohorts, respectively. An improvement in predictive performance was found by adding the ordinal scale of pre-arrest albumin levels to the original GO-FAR score.
TRPM7 is an essential regulator for volume-sensitive outwardly rectifying anion channel
Authors: Numata Tomohiro , Sato-Numata Kaori , Hermosura Meredith C. , Mori Yasuo , Okada Yasunobu 
Published: May 2021

AbstractAnimal cells can regulate their volume after swelling by the regulatory volume decrease (RVD) mechanism. In epithelial cells, RVD is attained through KCl release mediated via volume-sensitive outwardly rectifying Cl−channels (VSOR) and Ca2+-activated K+channels. Swelling-induced activation of TRPM7 cation channels leads to Ca2+influx, thereby stimulating the K+channels. Here, we examined whether TRPM7 plays any role in VSOR activation. When TRPM7 was knocked down in human HeLa cells or knocked out in chicken DT40 cells, not only TRPM7 activity and RVD efficacy but also VSOR activity were suppressed. Heterologous expression of TRPM7 in TRPM7-deficient DT40 cells rescued both VSOR activity and RVD, accompanied by an increase in the expression of LRRC8A, a core molecule of VSOR. TRPM7 exerts the facilitating action on VSOR activity first by enhancing molecular expression of LRRC8A mRNA through the mediation of steady-state Ca2+influx and second by stabilizing the plasmalemmal expression of LRRC8A protein through the interaction between LRRC8A and theC-terminal domain of TRPM7. Therefore, TRPM7 functions as an essential regulator of VSOR activity and LRRC8A expression.
Conformer-dependent vacuum ultraviolet photodynamics and chiral asymmetries in pure enantiomers of gas phase proline
Authors: Hadidi Rim , Božanić, Dušan K. , Ganjitabar Hassan , Garcia Gustavo A. , Powis Ivan , Nahon Laurent 
Published: May 2021

AbstractProline is a unique amino-acid, with a secondary amine fixed within a pyrrolidine ring providing specific structural properties to proline-rich biopolymers. Gas-phase proline possesses four main H-bond stabilized conformers differing by the ring puckering and carboxylic acid orientation. The latter defines two classes of conformation, whose large ionization energy difference allows a unique conformer-class tagging via electron spectroscopy. Photoelectron circular dichroism (PECD) is an intense chiroptical effect sensitive to molecular structures, hence theorized to be highly conformation-dependent. Here, we present experimental evidence of an intense and striking conformer-specific PECD, measured in the vacuum ultraviolet (VUV) photoionization of proline, as well as a conformer-dependent cation fragmentation behavior. This finding, combined with theoretical modeling, allows a refinement of the conformational landscape and energetic ordering, that proves inaccessible to current molecular electronic structure calculations. Additionally, astrochemical implications regarding a possible link of PECD to the origin of life’s homochirality are considered in terms of plausible temperature constraints.
A weakly-interacting many-body system of Rydberg polaritons based on electromagnetically induced transparency
Authors: Kim Bongjune , Chen Ko-Tang , Hsiao Shih-Si , Wang Sheng-Yang , Li Kai-Bo , Ruseckas Julius , Juzeliūnas Gediminas , Kirova Teodora , Auzinsh Marcis , Chen Ying-Cheng , Chen Yong-Fan , Yu Ite A. 
Published: May 2021

AbstractThe combination of Rydberg atoms and electromagnetically induced transparency (EIT) has been extensively studied in the strong-interaction regime. Here we proposed utilizing an EIT medium with a high optical depth (OD) and a Rydberg state of low principal quantum number to create a many-body system of Rydberg polaritons in the weak-interaction regime. The phase shift and attenuation induced by the dipole–dipole interaction (DDI) were still significant, and can be viewed as the consequences of elastic and inelastic collisions among Rydberg polaritons. We further observed that the width of the transverse momentum distribution of Rydberg polaritons at the exit of the system became notably smaller as compared with that at the entrance. The observation demonstrates the cooling effect in this system. The μs-long interaction time due to the high-OD EIT medium plus the μm2-size collision cross section due to the DDI suggests a feasible platform of polariton Bose–Einstein condensation.
Interannual oxygen isotope variability in Indian summer monsoon precipitation reflects changes in moisture sources
Authors: Kathayat Gayatri , Sinha Ashish , Tanoue Masahiro , Yoshimura Kei , Li Hanying , Zhang Haiwei , Cheng Hai 
Published: May 2021

AbstractThe primary influences on the spatio-temporal variability of oxygen isotope compositions in precipitation over the Indian summer monsoon domain are inadequately constrained by the limited observational record. Consequently, the climatic significance of isotopic signatures of precipitation preserved in proxy archives from the region remains unclear. Here we present simulations with an isotope-enabled climate model (IsoGSM2) with the moisture-tagging capability to investigate the role of relative contributions of moisture from oceanic and terrestrial sources to the interannual variability in oxygen isotope composition in summer monsoon rainfall. During weak monsoon years, the moisture contribution from the Arabian Sea dominates precipitation over the Indian subcontinent while the remote oceanic and terrestrial sources have a greater influence during strong monsoon years. We suggest that changes in monsoon circulation, moisture source, and precipitation intensity are interrelated and that speleothem oxygen isotope records from the region can potentially help reconstruct interannual to decadal monsoon rainfall variability.
Co-biomembrane-coated Fe3O4/MnO2 multifunctional nanoparticles for targeted delivery and enhanced chemodynamic/photothermal/chemo therapy
Authors: Guo Yingshu , Zheng Xiaofei , Gai Tingting , Wei Zhiyong , Zhang Shusheng 
Published: May 2021

Fe3O4/MnO2 biomimetic nanoplatform has good Fenton catalytic activity and photothermal conversion efficiency, combined with good targeting ability, which can be used to improve the therapeutic efficiency.
Emerging role of carbonic anhydrase inhibitors
Authors: Supuran Claudiu T. 
Published: May 2021

Abstract
Inhibition of carbonic anhydrase (CA, EC 4.2.1.1) was clinically exploited for decades, as most modern diuretics were obtained considering as lead molecule acetazolamide, the prototypical CA inhibitor (CAI). The discovery and characterization of multiple human CA (hCA) isoforms, 15 of which being known today, led to new applications of their inhibitors. They include widely clinically used antiglaucoma, antiepileptic and antiobesity agents, antitumor drugs in clinical development, as well as drugs for the management of acute mountain sickness and idiopathic intracranial hypertension (IIH). Emerging roles of several CA isoforms in areas not generally connected to these enzymes were recently documented, such as in neuropathic pain, cerebral ischemia, rheumatoid arthritis, oxidative stress and Alzheimer’s disease. Proof-of-concept studies thus emerged by using isoform-selective inhibitors, which may lead to new clinical applications in such areas. Relevant preclinical models are available for these pathologies due to the availability of isoform-selective CAIs for all human isoforms, belonging to novel classes of compounds, such as coumarins, sulfocoumarins, dithiocarbamates, benzoxaboroles, apart the classical sulfonamide inhibitors. The inhibition of CAs from pathogenic bacteria, fungi, protozoans or nematodes started recently to be considered for obtaining anti-infectives with a new mechanism of action.