bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydro‐Geochemical and Sr Isotope Characteristics of the Yalong River Basin, Eastern Tibetan Plateau: Implications for Chemical Weathering and Controlling Factors
Authors: Zhang Xuan , Xu Zhifang , Liu Wenjing , Moon Seulgi , Zhao Tong , Zhou Xiaode , Zhang Jiangyi , Wu Yao , Jiang Hao , Zhou Li 
Published: January 2019

AbstractMajor ions and Sr isotope compositions of waters in the Yalong River basin in the eastern Tibetan plateau were investigated to explore the sources of dissolved loads and the controls on chemical weathering rates. Measured radiogenic 87Sr/86Sr ratios of water samples are most likely derived from the weathering of metamorphic carbonates or the Precambrian silicate rocks. Quantitative analysis of water geochemistry shows that carbonate weathering dominates the chemical characteristics of the river water. The chemical weathering rate of the whole Yalong River basin is calculated to be 7.6 ton·km−2·year−1 by silicate weathering and 44.7 ton·km−2·year−1 by carbonate weathering, which consumes 158.5 × 103 and 885.0 × 103 mol·km−2·year−1 of atmospheric CO2, respectively. The highest carbonate weathering rate (116.3 ton·km−2·year−1) in the Yalong River basins is observed from the basin with the steepest catchment average slope. This highest magnitude of carbonate weathering is comparable to the rates from catchments in the southern Himalayas. Positive relationships are observed between silicate weathering rates and both climatic (precipitation and temperature) and topographic (relief and slope) controls. The combined climatic and tectonic effects increase silicate weathering and counterbalance the dilution effect. However, the relationship between silicate weathering rate and climatic and topographic controls varies with hydrologic conditions. The rate for low‐discharge catchments is more closely related to climatic parameters, while the rate for high‐discharge catchments is more closely related to local topography.
Wintertime fCO2 Variability in the Subpolar North Atlantic Since 2004
Authors: Fröb F. , Olsen A. , Becker M. , Chafik L. , Johannessen T. , Reverdin G. , Omar A. 
Published: January 2019

AbstractWinter data of surface ocean temperature (SST), salinity (SSS) and CO2 fugacity (fCO2) collected on the VOS M/V Nuka Arctica in the subpolar North Atlantic between 2004 and 2017 are used to establish trends, drivers, and interannual variability. Over the period, waters cooled and freshened, and the fCO2 increased at a rate similar to the atmospheric CO2 growth rate. When accounting for the freshening, the inferred increase in dissolved inorganic carbon (DIC) was found to be approximately twice that expected from atmospheric CO2 alone. This is attributed to the cooling. In the Irminger Sea, fCO2 exhibited additional interannual variations driven by atmospheric forcing through winter mixing. As winter fCO2 in the region is close to the atmospheric, the subpolar North Atlantic has varied between being slightly supersaturated and slightly undersaturated over the investigated period.
Detection of Rotational Acceleration of Bennu Using HST Light Curve Observations
Authors: Nolan M. C. , Howell E. S. , Scheeres D. J. , McMahon J. W. , Golubov O. , Hergenrother C. W. , Emery J. P. , Noll K. S. , Chesley S. R. , Lauretta D. S. 
Published: January 2019

AbstractWe observed the near‐Earth asteroid (101955) Bennu from the ground in 1999 and 2005, and with the Hubble Space Telescope (HST) in 2012, to constrain its rotation rate. The data reveal an acceleration of 2.64 ± 1.05 × 10−6 deg/day2, which could be due to a change in the moment of inertia of Bennu or to spin up from the Yarkovsky‐O'Keefe‐Radzievskii‐Paddack effect or other source of angular momentum. The best solution is within 1 σ of the period determined by Nolan et al. (2013, https://doi.org/10.1016/j.icarus.2013.05.028). The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission will determine the rotation state independently in 2019. Those measurements should show whether the change in rotation rate is a steady increase (due, e.g., to the Yarkovsky‐O'Keefe‐Radzievskii‐Paddack effect) or some other phenomenon. The precise shape and surface properties measured by the OSIRIS‐REx science team will allow for a better understanding of variations in rotation rate of small asteroids.
Substantial Reductions in Cloud Cover and Moisture Transport by Dynamic Plant Responses
Authors: Sikma Martin , Vilà‐Guerau de Arellano Jordi 
Published: January 2019

AbstractCumulus clouds make a significant contribution to the Earth's energy balance and hydrological cycle and are a major source of uncertainty in climate projections. Reducing uncertainty by expanding our understanding of the processes that drive cumulus convection is vital to the accurate identification of future global and regional climate impacts. Here we adopt an interdisciplinary approach that integrates interrelated scales from plant physiology to atmospheric turbulence. Our explicit simulations mimic the land‐atmosphere approach implemented in current numerical weather prediction, and global climate models enable us to conclude that neglecting local plant dynamic responses leads to misrepresentations in the cloud cover and midtropospheric moisture convection of up to 21% and 56%, respectively. Our approach offers insights into the key role played by the active vegetation on atmospheric convective mixing that has recently been identified as the source of half of the variance in global warming projections (i.e., equilibrium climate sensitivity).
Alfvén Wave Propagation in the Io Plasma Torus
Authors: Hinton P. C. , Bagenal F. , Bonfond B. 
Published: January 2019

AbstractIo, the most volcanically active body in the solar system, fuels a plasma torus around Jupiter with dissociation products of SO2 at a rate of ~1,000 kg/s. We use a combination of in situ Voyager 1 data and Cassini Ultraviolet Imaging Spectrograph observations to constrain a diffusive equilibrium model of the Io plasma torus. The interaction of the Io plasma torus with Io launches Alfvén waves in both directions along magnetic field lines. We use the recent Juno‐based JRM09 magnetic field model combined with our 3‐D model of the Io plasma torus to simulate the propagation of Alfvén waves from the moon to the ionosphere of Jupiter. We map the location of multiple reflections of iogenic Alfvén waves between the northern and southern hemispheres. The location of the first few bounces of the Alfvén wave pattern match the Io auroral footprints observed by the Hubble Space Telescope.
Observations of Evolution‐Type Band‐Like Structures of F Region Irregularities
Authors: Meng Xing , Fang Hanxian , Li Guozhu , Weng Libin , Wang Sicheng 
Published: January 2019

AbstractGenerally, equatorial spread‐F (ESF) irregularities initiated at the bottom of the ionospheric F region and manifested as plume structures with an altitude extent more than 50 km in the RTI (range‐time‐intensity) plot. By using the Fuke and Sanya VHF radars located at low latitude of China, evolution‐type band‐like structures of ESF irregularities were observed near local sunset. One interesting aspect is that the ESF band‐like structures initially appeared at high altitudes more than 400 km and then uplifted to higher altitude without zonal propagation. The lifetime of these ESF band‐like structures, with a similar pattern in the RTI plot for each beam of radar, is less than 25 min. The band‐like structures of F region irregularities were observed with big Doppler velocities and narrow spectral widths. During the presence of ESF band‐like structures, apparent amplitude scintillations (S4 > 0.2), total electron content (TEC) fast fluctuations (ROTI > 1), and range‐type spread F were detected. Possible mechanisms responsible for the initial generation of band‐like ESF irregularities at high altitude are discussed.
Helios Observations of Quasiperiodic Density Structures in the Slow Solar Wind at 0.3, 0.4, and 0.6 AU
Authors: Di Matteo S. , Viall N. M. , Kepko L. , Wallace S. , Arge C. N. , MacNeice P. 
Published: January 2019

AbstractFollowing previous investigations of quasiperiodic plasma density structures in the solar wind at 1 AU, we show using the Helios1 and Helios2 data their first identification in situ in the inner heliosphere at 0.3, 0.4, and 0.6 AU. We present five events of quasiperiodic density structures with time scales ranging from a few minutes to a couple of hours in slow solar wind streams. Where possible, we locate the solar source region of these events using photospheric field maps from the Mount Wilson Observatory as input for the Wang‐Sheeley‐Arge model. The detailed study of the plasma properties of these structures is fundamental to understanding the physical processes occurring at the origin of the release of solar wind plasma. Temperature changes associated with the density structures are consistent with these periodic structures developing in the solar atmosphere as the solar wind is formed. One event contains a flux rope, suggesting that the solar wind was formed as magnetic reconnection opened up a previously closed flux tube at the Sun. This study highlights the types of structures that Parker Solar Probe and the upcoming Solar Orbiter mission will observe, and the types of data analyses these missions will enable. The data from these spacecrafts will provide additional in situ measurements of the solar wind properties in the inner heliosphere allowing, together with the information of the other interplanetary probes, a more comprehensive study of solar wind formation.
Stress‐Strain Evolution During Peak‐Ring Formation: A Case Study of the Chicxulub Impact Structure
Authors: Rae Auriol S. P. , Collins Gareth S. , Poelchau Michael , Riller Ulrich , Davison Thomas M. , Grieve Richard A. F. , Osinski Gordon R. , Morgan Joanna V. , IODP‐ICDP Expedition 364 Scientists  
Published: January 2019

AbstractDeformation is a ubiquitous process that occurs to rocks during impact cratering; thus, quantifying the deformation of those rocks can provide first‐order constraints on the process of impact cratering. Until now, specific quantification of the conditions of stress and strain within models of impact cratering has not been compared to structural observations. This paper describes a methodology to analyze stress and strain within numerical impact models. This method is then used to predict deformation and its cause during peak‐ring formation: a complex process that is not fully understood, requiring remarkable transient weakening and causing a significant redistribution of crustal rocks. The presented results are timely due to the recent Joint International Ocean Discovery Program and International Continental Scientific Drilling Program drilling of the peak ring within the Chicxulub crater, permitting direct comparison between the deformation history within numerical models and the structural history of rocks from a peak ring. The modeled results are remarkably consistent with observed deformation within the Chicxulub peak ring, constraining the following: (1) the orientation of rocks relative to their preimpact orientation; (2) total strain, strain rates, and the type of shear during each stage of cratering; and (3) the orientation and magnitude of principal stresses during each stage of cratering. The methodology and analysis used to generate these predictions is general and, therefore, allows numerical impact models to be constrained by structural observations of impact craters and for those models to produce quantitative predictions.
Temporal Scaling of Carbon Emission and Accumulation Rates: Modern Anthropogenic Emissions Compared to Estimates of PETM Onset Accumulation
Authors: Gingerich Philip D. 
Published: January 2019

AbstractThe Paleocene‐Eocene thermal maximum (PETM) was caused by a massive release of carbon to the atmosphere. This is a benchmark global greenhouse warming event that raised temperatures to their warmest since extinction of the dinosaurs. Rates of carbon emission today can be compared to those during onset of the PETM in two ways: (1) projection of long‐term PETM rates for comparison on an annual time scale and (2) projection of short‐term modern rates for comparison on a PETM time scale. Both require temporal scaling and extrapolation for comparison on the same time scale. PETM rates are few and projection to a short time scale is poorly constrained. Modern rates are many, and projection to a longer PETM time scale is tightly constrained—modern rates are some 9–10 times higher than those during onset of the PETM. If the present trend of anthropogenic emissions continues, we can expect to reach a PETM‐scale accumulation of atmospheric carbon in as few as 140 to 259 years (about 5 to 10 human generations).
Comprehensive functional annotation of susceptibility SNPs prioritized 10 genes for schizophrenia
Authors: Niu Hui-Min , Yang Ping , Chen Huan-Huan , Hao Ruo-Han , Dong Shan-Shan , Yao Shi , Chen Xiao-Feng , Yan Han , Zhang Yu-Jie , Chen Yi-Xiao , Jiang Feng , Yang Tie-Lin , Guo Yan 
Published: January 2019

AbstractNearly 95% of susceptibility SNPs identified by genome-wide association studies (GWASs) are located in non-coding regions, which causes a lot of difficulty in deciphering their biological functions on disease pathogenesis. Here, we aimed to conduct a comprehensive functional annotation for all the schizophrenia susceptibility loci obtained from GWASs. Considering varieties of epigenomic regulatory elements, we annotated all 22,688 acquired susceptibility SNPs according to their genomic positions to obtain functional SNPs. The comprehensive annotation indicated that these functional SNPs are broadly involved in diverse biological processes. Histone modification enrichment showed that H3K27ac, H3K36me3, H3K4me1, and H3K4me3 were related to the development of schizophrenia. Transcription factors (TFs) prediction, methylation quantitative trait loci (meQTL) analyses, expression quantitative trait loci (eQTL) analyses, and proteomic quantitative trait loci analyses (pQTL) identified 447 target protein-coding genes. Subsequently, differential expression analyses between schizophrenia cases and controls, nervous system phenotypes from mouse models, and protein–protein interaction with known schizophrenia-related pathways and genes were carried out with our target genes. We finaly prioritized 10 target genes for schizophrenia (CACNA1C, CLU, CSNK2B, GABBR1, GRIN2A, MAPK3, NOTCH4, SRR, TNF, and SYNGAP1). Our results may serve as an encyclopedia of schizophrenia susceptibility SNPs and offer holistic guides for post-GWAS functional experiments.
Catalytic enantioselective construction of axial chirality in 1,3-disubstituted allenes
Authors: Song Shihua , Zhou Jing , Fu Chunling , Ma Shengming 
Published: January 2019

AbstractMetal-catalyzed enantioselective construction of the loosening axial allene chirality spreading over three carbon atoms using a chiral ligand is still a significant challenge. In the literature, steric effect of the substrates is the major strategy applied for such a purpose. Herein, we present a general palladium-catalyzed asymmetrization of readily available racemic 2,3-allenylic carbonates with different types of non-substituted and 2-substituted malonates using (R)-(−)-DTBM-SEGPHOS as the preferred ligand to afford 1,3-disubstituted chiral allenes with 90~96% ee. This protocol has been applied to the first enantioselective synthesis of natural product, (R)-traumatic lactone. Control experiments showed that in addition to the chiral ligand, conducting this transformation via Procedure C, which excludes the extensive prior coordination of the allene unit in the starting allene with Pd forming a species without the influence of the chiral ligand, is crucial for the observed high enantioselectivity.
Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters
Authors: Lloret Vicent , Rivero-Crespo Miguel Ángel , Vidal-Moya José Alejandro , Wild Stefan , Doménech-Carbó Antonio , Heller Bettina S. J. , Shin Sunghwan , Steinrück Hans-Peter , Maier Florian , Hauke Frank , Varela Maria , Hirsch Andreas , Leyva-Pérez Antonio , Abellán Gonzalo 
Published: January 2019

AbstractGroup 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well–structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid–catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid–sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents.
Control of MXenes’ electronic properties through termination and intercalation
Authors: Hart James L. , Hantanasirisakul Kanit , Lang Andrew C. , Anasori Babak , Pinto David , Pivak Yevheniy , van Omme J. Tijn , May Steven J. , Gogotsi Yury , Taheri Mitra L. 
Published: January 2019

AbstractMXenes are an emerging family of highly-conductive 2D materials which have demonstrated state-of-the-art performance in electromagnetic interference shielding, chemical sensing, and energy storage. To further improve performance, there is a need to increase MXenes’ electronic conductivity. Tailoring the MXene surface chemistry could achieve this goal, as density functional theory predicts that surface terminations strongly influence MXenes' Fermi level density of states and thereby MXenes’ electronic conductivity. Here, we directly correlate MXene surface de-functionalization with increased electronic conductivity through in situ vacuum annealing, electrical biasing, and spectroscopic analysis within the transmission electron microscope. Furthermore, we show that intercalation can induce transitions between metallic and semiconductor-like transport (transitions from a positive to negative temperature-dependence of resistance) through inter-flake effects. These findings lay the groundwork for intercalation- and termination-engineered MXenes, which promise improved electronic conductivity and could lead to the realization of semiconducting, magnetic, and topologically insulating MXenes.
Modular Design of Programmable Mechanofluorescent DNA Hydrogels
Authors: Merindol Remi , Delechiave Giovanne , Heinen Laura , Catalani Luiz Henrique , Walther Andreas 
Published: January 2019

AbstractMechanosensing systems are ubiquitous in nature and control many functions from cell spreading to wound healing. Biologic systems typically rely on supramolecular transformations and secondary reporter systems to sense weak forces. By contrast, synthetic mechanosensitive materials often use covalent transformations of chromophores, serving both as force sensor and reporter, which hinders orthogonal engineering of their sensitivity, response and modularity. Here, we introduce FRET-based, rationally tunable DNA tension probes into macroscopic 3D all-DNA hydrogels to prepare mechanofluorescent materials with programmable sacrificial bonds and stress relaxation. This design addresses current limitations of mechanochromic system by offering spatiotemporal resolution, as well as quantitative and modular force sensing in soft hydrogels. The programmable force probe design further grants temporal control over the recovery of the mechanofluorescence during stress relaxation, enabling reversible and irreversible strain sensing. We show proof-of-concept applications to study strain fields in composites and to visualize freezing-induced strain patterns in homogeneous hydrogels.
The antimicrobial potential of Streptomyces from insect microbiomes
Authors: Chevrette Marc G. , Carlson Caitlin M. , Ortega Humberto E. , Thomas Chris , Ananiev Gene E. , Barns Kenneth J. , Book Adam J. , Cagnazzo Julian , Carlos Camila , Flanigan Will , Grubbs Kirk J. , Horn Heidi A. , Hoffmann F. Michael , Klassen Jonathan L. , Knack Jennifer J. , Lewin Gina R. , McDonald Bradon R. , Muller Laura , Melo Weilan G. P. , Pinto-Tomás Adrián A. , Schmitz Amber , Wendt-Pienkowski Evelyn , Wildman Scott , Zhao Miao , Zhang Fan , Bugni Tim S. , Andes David R. , Pupo Monica T. , Currie Cameron R. 
Published: January 2019

AbstractAntimicrobial resistance is a global health crisis and few novel antimicrobials have been discovered in recent decades. Natural products, particularly from Streptomyces, are the source of most antimicrobials, yet discovery campaigns focusing on Streptomyces from the soil largely rediscover known compounds. Investigation of understudied and symbiotic sources has seen some success, yet no studies have systematically explored microbiomes for antimicrobials. Here we assess the distinct evolutionary lineages of Streptomyces from insect microbiomes as a source of new antimicrobials through large-scale isolations, bioactivity assays, genomics, metabolomics, and in vivo infection models. Insect-associated Streptomyces inhibit antimicrobial-resistant pathogens more than soil Streptomyces. Genomics and metabolomics reveal their diverse biosynthetic capabilities. Further, we describe cyphomycin, a new molecule active against multidrug resistant fungal pathogens. The evolutionary trajectories of Streptomyces from the insect microbiome influence their biosynthetic potential and ability to inhibit resistant pathogens, supporting the promise of this source in augmenting future antimicrobial discovery.
Direct functionalization of methane into ethanol over copper modified polymeric carbon nitride via photocatalysis
Authors: Zhou Yuanyi , Zhang Ling , Wang Wenzhong 
Published: January 2019

AbstractDirect valorization of methane to its alcohol derivative remains a great challenge. Photocatalysis arises as a promising green strategy which could exploit hydroxyl radical (·OH) to accomplish methane activation. However, both the excessive ·OH from direct H2O oxidation and the neglect of methane activation on the material would cause deep mineralization. Here we introduce Cu species into polymeric carbon nitride (PCN), accomplishing photocatalytic anaerobic methane conversion for the first time with an ethanol productivity of 106 μmol gcat−1 h−1. Cu modified PCN could manage generation and in situ decomposition of H2O2 to produce ·OH, of which Cu species are also active sites for methane adsorption and activation. These features avoid excess ·OH for overoxidation and facilitate methane conversion. Moreover, a hypothetic mechanism through a methane-methanol-ethanol pathway is proposed, emphasizing the synergy of Cu species and the adjacent C atom in PCN for obtaining C2 product.