bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vertical midscale ionospheric disturbances caused by surface seismic waves based on Irkutsk chirp ionosonde data in 2011–2016
Authors: Berngardt O. I. , Perevalova N. P. , Podlesnyi A. V. , Kurkin V. I. , Zherebtsov G. A. 
Published: April 2017

AbstractBased on the Irkutsk fast monostatic chirp ionosonde data, we made a statistical analysis of ionospheric effects for 28 earthquakes which appeared in 2011–2016 years. These effects are related with surface (Rayleigh) seismic waves far from epicenter. The analysis has shown that nine of these earthquakes were accompanied by vertical midscale ionospheric irregularities (multicusp). To estimate the ionospheric efficiency of the seismic waves, we proposed new index KW. The index estimates the maximal amplitude of the acoustic shock wave generated by given spatial distribution of seismic vibrations and related with maximal spectral power of seismic oscillations. Based on the analysis of experimental data, we have shown that earthquake‐related multicusp (5–25 s irregularities) is observed mostly at daytime [07:00–17:00] LST for KW≥4.7. The observations of acoustic waves by GPS technique in the epicenter vicinity (120–600 s irregularities) do not show such a daytime dependence. Based on 24 May 2013 Okhotsk Sea earthquake example, we demonstrated that deep‐focus earthquakes can produce strong multicusp far from the epicenter, although do not produce significant GPS ionospheric response in the epicenter vicinity.
Formation of multiple energy dispersion of H+, He+, and O+ ions in the inner magnetosphere in response to interplanetary shock
Authors: Tsuji H. , Ebihara Y. , Tanaka T. 
Published: April 2017

AbstractAn interplanetary (IP) shock has a large impact on magnetospheric ions. Satellite observations have shown that soon after arrival of the IP shock, overall intensity of the ions rapidly increases and multiple energy dispersion appears in an energy‐time spectrogram of the ions. In order to understand the response of the magnetospheric ions to IP shock, we have performed test particle simulation under the electric and magnetic fields provided by the global magnetohydrodynamic simulation. We reconstructed the differential flux of H+, He+, and O+ ions at (7, 0, 0) Re in GSM coordinates by means of the semi‐Lagrangian (phase space mapping) method. Simulation results show that the ions respond to the IP shock in two different ways. First, overall intensity of the flux gradually increases at all pitch angles. As the compressional wave propagates tailward, the magnetic field increases, which accelerates the ions due to the gyrobetatron. Second, multiple energy‐time dispersion appears in the reconstructed spectrograms of the ion flux. The energy‐time dispersion is caused by the ion moving toward mirror point together with tailward propagating compressional wave at off‐equator. The ions are primarily accelerated by the drift betatron under the strong electric field looking dawnward. The dispersion is absent in the spectrogram of equatorially mirroring ions. The dispersion appears at higher energy for heavier ions. These features are consistent with the satellite observations. Because the acceleration depends on bounce phase, the bounce‐averaged approximation is probably invalid for the ions during the interval of geomagnetic sudden commencement.
Flow and turbulence structure in a hypertidal estuary with the world's biggest tidal bore
Authors: Tu Junbiao , Fan Daidu 
Published: April 2017

AbstractTurbulent and flow structure associated with breaking tidal bores are deliberately investigated on the basis of field measurements. High‐resolution velocity and hydrographic data are collected in the middle Qiantang Estuary by a vertical array of acoustic Doppler velocimeters and optical backscatter sensors, collaborated with a bottom‐mounted acoustic Doppler current profiler. Besides obvious variations in diurnal and spring‐neap tidal cycles, the estuarine dynamics is featured by extreme asymmetry in flood and ebb tides. The flood tide is abnormally accelerated to generate tidal bores at the first 10 min or more, with breaking or undular configurations at the front. The occurrence of peak flow velocity, turbulent kinetic energy (TKE), and TKE dissipation rate (ε) is definitely associated with breaking bores, with their values several times to 2 orders of magnitude larger than the corresponding secondary peak values during the maximum ebb flows. Flow and turbulence dynamics are significantly affected by the tidal‐bore Froude number. A sandwich ε structure is clear exhibited with the maximum value at the surface, secondary maximum near the bed, and the minimum at the intermediate. Dual TKE sources are indicated by an approximate local balance between shear production and dissipation near the bottom, and a top‐down TKE dissipation using the modified Froude scaling in the vertical water column. The highly elevated dissipation by breaking bores is comparable to that by intense breaking waves in the surf zone, and the former potentially penetrates the entire water column to produce extreme sediment‐resuspension events in combination with intense bottom shear stress.
Nonbreaking wave‐induced mixing in upper ocean during tropical cyclones using coupled hurricane‐ocean‐wave modeling
Authors: Aijaz S. , Ghantous M. , Babanin A. V. , Ginis I. , Thomas B. , Wake G. 
Published: April 2017

AbstractThe effects of turbulence generated by nonbreaking waves have been investigated by testing and evaluating a new nonbreaking wave parameterization in a coupled hurricane‐ocean‐wave model. The MPI version of the Princeton Ocean Model (POM) with hurricane forcing is coupled with the WAVEWATCH‐III (WW3) surface wave model. Hurricane Ivan is chosen as the test case due to its extreme intensity and availability of field data during its passage. The model results are validated against field observations of wave heights and sea surface temperatures (SSTs) from the National Data Buoy Centre (NDBC) during Hurricane Ivan and against limited in situ current and bottom temperature data. A series of numerical experiments is set up to examine the influence of the nonbreaking wave parameterization on the mixing of upper ocean. The SST response from the modeling experiments indicates that the nonbreaking wave‐induced mixing leads to significant cooling of the SST and deepening of the mixed layer. It was found that the nondimensional constant b1 in the nonbreaking wave parameterization has different impacts on the weak and the strong sides of the storm track. A constant value of b1 leads to improved predictions on the strong side of the storm while a steepness‐dependent b1 provides a better agreement with in situ observations on the weak side. A separate simulation of the intense tropical cyclone Olwyn in north‐west Australia revealed the same trend for b1 on the strong side of the tropical cyclone.
Turbulent kinetic energy of the ocean winds over the Kuroshio Extension from QuikSCAT winds (1999–2009)
Authors: Yu Kai , Dong Changming , King Gregory P. 
Published: April 2017

AbstractWe investigate mesoscale turbulence (10–1000 km) in the ocean winds over the Kuroshio Extension (
N–
N,
E–
E) using the QuikSCAT data set (November 1999 to October 2009). We calculate the second (Djj) and third‐order structure functions (Djjj) and the spatial variance (Vj) as a function of scale r (
denotes, respectively, the longitudinal (divergent) and transverse (vortical) component). The most interesting results of the analysis follow. Although both
and
measure the turbulent kinetic energy (TKE), we find that
is the more robust measure. The spatial variance density (dVj/dr) has a broad peak near 450 km (close to the midlatitude Rossby radius of deformation). On interannual time scales, TKE correlates well with the El Niño 3.4 index. According to turbulence theory, the kinetic energy cascades downscale (upscale) if
(also skewness
) is negative (positive). Our results for the Kuroshio Extension are consistent with a downscale cascade (indicating convergence dominates). Furthermore, classical turbulence theory predicts that
and independent of r; however, we find SL varies strongly with r, from −4 at small scales to −0.3 at large scales. This nonclassical behavior implies strong‐scale interaction, which we attribute to the rapid, and sometimes explosive, growth of storms in the region through baroclinic instability. Finally, we find that ST (a measure of cyclonic/anticyclonic asymmetry) is positive (cyclonic) and also varies strongly with r, from 4 at small scales to 0.5 at large scales. New turbulence models are needed to explain these results, and that will benefit Weather Prediction and climate modeling.
A probabilistic approach to remote compositional analysis of planetary surfaces
Authors: Lapotre M. G. A. , Ehlmann B. L. , Minson S. E. 
Published: April 2017

AbstractReflected light from planetary surfaces provides information, including mineral/ice compositions and grain sizes, by study of albedo and absorption features as a function of wavelength. However, deconvolving the compositional signal in spectra is complicated by the nonuniqueness of the inverse problem. Trade‐offs between mineral abundances and grain sizes in setting reflectance, instrument noise, and systematic errors in the forward model are potential sources of uncertainty, which are often unquantified. Here we adopt a Bayesian implementation of the Hapke model to determine sets of acceptable‐fit mineral assemblages, as opposed to single best fit solutions. We quantify errors and uncertainties in mineral abundances and grain sizes that arise from instrument noise, compositional end members, optical constants, and systematic forward model errors for two suites of ternary mixtures (olivine‐enstatite‐anorthite and olivine‐nontronite‐basaltic glass) in a series of six experiments in the visible‐shortwave infrared (VSWIR) wavelength range. We show that grain sizes are generally poorly constrained from VSWIR spectroscopy. Abundance and grain size trade‐offs lead to typical abundance errors of ≤1 wt % (occasionally up to ~5 wt %), while ~3% noise in the data increases errors by up to ~2 wt %. Systematic errors further increase inaccuracies by a factor of 4. Finally, phases with low spectral contrast or inaccurate optical constants can further increase errors. Overall, typical errors in abundance are <10%, but sometimes significantly increase for specific mixtures, prone to abundance/grain‐size trade‐offs that lead to high unmixing uncertainties. These results highlight the need for probabilistic approaches to remote determination of planetary surface composition.
Hydrological controls on glacially exported microbial assemblages
Authors: Dubnick Ashley , Kazemi Sina , Sharp Martin , Wadham Jemma , Hawkings Jon , Beaton Alexander , Lanoil Brian 
Published: April 2017

AbstractThe Greenland Ice Sheet (GrIS) exports approximately 400 km3 of freshwater annually to downstream freshwater and marine ecosystems. These meltwaters originate in a wide range of well‐defined habitats that can be associated with very different physical environments within the ice sheet, ranging from oxygenated surface environments that are exposed to light and supplied with nutrients from atmospheric/aeolian sources to subglacial environments that are permanently dark, isolated from the atmosphere, and potentially anoxic. Hydrological conditions in the latter likely favor prolonged rock‐water contact. The seasonally evolving hydrological system that drains meltwaters from the GrIS connects these distinct microbial habitats and exports the microbes contained within them to downstream ecosystems. The microbial assemblages exported in glacier meltwater may have an impact on downstream ecosystem function and development. We explored how the seasonal development of a glacial drainage system influences the character of microbial assemblages exported from the GrIS by monitoring the seasonal changes in hydrology, water chemistry, and microbial assemblage composition of meltwaters draining from a glacier in southwest Greenland. We found that the microbial assemblages exported in meltwaters varied in response to glacier hydrological flow path characteristics. Whether or not meltwaters passed through the subglacial environment was the first‐order control on the composition of the microbial assemblages exported from the glacier, while water source (i.e., supraglacial or extraglacial) and subglacial residence times were second‐order controls. Glacier hydrology therefore plays a fundamental role in determining the microbial exports from glaciated watersheds.
Spatial heterogeneity of within‐stream methane concentrations
Authors: Crawford John T. , Loken Luke C. , West William E. , Crary Benjamin , Spawn Seth A. , Gubbins Nicholas , Jones Stuart E. , Striegl Robert G. , Stanley Emily H. 
Published: April 2017

AbstractStreams, rivers, and other freshwater features may be significant sources of CH4 to the atmosphere. However, high spatial and temporal variabilities hinder our ability to understand the underlying processes of CH4 production and delivery to streams and also challenge the use of scaling approaches across large areas. We studied a stream having high geomorphic variability to assess the underlying scale of CH4 spatial variability and to examine whether the physical structure of a stream can explain the variation in surface CH4. A combination of high‐resolution CH4 mapping, a survey of groundwater CH4 concentrations, quantitative analysis of methanogen DNA, and sediment CH4 production potentials illustrates the spatial and geomorphic controls on CH4 emissions to the atmosphere. We observed significant spatial clustering with high CH4 concentrations in organic‐rich stream reaches and lake transitions. These sites were also enriched in the methane‐producing mcrA gene and had highest CH4 production rates in the laboratory. In contrast, mineral‐rich reaches had significantly lower concentrations and had lesser abundances of mcrA. Strong relationships between CH4 and the physical structure of this aquatic system, along with high spatial variability, suggest that future investigations will benefit from viewing streams as landscapes, as opposed to ecosystems simply embedded in larger terrestrial mosaics. In light of such high spatial variability, we recommend that future workers evaluate stream networks first by using similar spatial tools in order to build effective sampling programs.
Modes of temperature and pressure variability in midlatitude troposphere and lower stratosphere in relation to cosmic ray variations
Authors: Morozova A. L. , Blanco J. J. , Ribeiro P. 
Published: April 2017

AbstractThe study is based on the analysis of atmospheric and space weather parameters in the midlatitude region (Iberian Peninsula) during, approximately, the epoch of the 24th solar cycle maximum. The principal component analysis was applied to sets of air temperature and geopotential height measurement at different pressure levels from a near‐ground level (930 hPa) to the stratosphere (up to 10 hPa). The analysis of extracted modes shows couplings between atmospheric and medium‐term variations (from weeks to months) of space weather parameters. The first mode of the atmospheric variability is related to the atmospheric dynamic processes that are common for the extratropical Northern Hemisphere. Extracted temperature and pressure variations are located in the upper troposphere‐lower stratosphere region and positively correlate with ozone content variations. Among space weather parameters, this atmospheric mode shows statistically significant negative correlation with the ground‐measured cosmic ray flux measured by the Castilla‐La Mancha neutron monitor (Spain) and weaker or no correlation with geomagnetic parameters.
Physical effects of thermal pollution in lakes
Authors: Råman Vinnå Love , Wüest Alfred , Bouffard Damien 
Published: April 2017

AbstractAnthropogenic heat emissions into inland waters influence water temperature and affect stratification, heat and nutrient fluxes, deep water renewal, and biota. Given the increased thermal stress on these systems by growing cooling demands of riparian/coastal infrastructures in combination with climate warming, the question arises on how to best monitor and manage these systems. In this study, we investigate local and system‐wide physical effects on the medium‐sized perialpine Lake Biel (Switzerland), influenced by point‐source cooling water emission from an upstream nuclear power plant (heat emission ∼700 MW, ∼18 W m−2 lake wide). We use one‐dimensional (SIMSTRAT) and three‐dimensional (Delft3D‐Flow) hydrodynamic numerical simulations and provide model resolution guidelines for future studies of thermal pollution. The effects on Lake Biel by the emitted excess heat are summarized as: (i) clear seasonal trend in temperature increase, locally up to 3.4°C and system‐wide volume mean ∼0.3°C, which corresponds to one decade of regional surface water climate warming; (ii) the majority of supplied thermal pollution (∼60%) leaves this short residence time (∼58 days) system via the main outlet, whereas the remaining heat exits to the atmosphere; (iii) increased length of stratified period due to the stabilizing effects of additional heat; (iv) system‐wide effects such as warmer temperature, prolonged stratified period, and river‐caused epilimnion flushing are resolved by both models whereas local raised temperature and river short circuiting was only identifiable with the three‐dimensional model approach. This model‐based method provides an ideal tool to assess man‐made impacts on lakes and their downstream outflows.
Persistent or repeated surface habitability on Mars during the late Hesperian ‐ Amazonian
Authors: Kite Edwin S. , Sneed Jonathan , Mayer David P. , Wilson Sharon A. 
Published: April 2017

AbstractLarge alluvial fan deposits on Mars record relatively recent habitable surface conditions (≲3.5 Ga, Late Hesperian ‐ Amazonian). We find net sedimentation rate <(4–8) μm/yr in the alluvial fan deposits, using the frequency of craters that are interbedded with alluvial fan deposits as a fluvial‐process chronometer. Considering only the observed interbedded craters sets a lower bound of >20 Myr on the total time interval spanned by alluvial fan aggradation, >103‐fold longer than previous lower limits. A more realistic approach that corrects for craters fully entombed in the fan deposits raises the lower bound to >(100–300) Myr. Several factors not included in our calculations would further increase the lower bound. The lower bound rules out fan formation by a brief climate anomaly. Therefore, during the Late Hesperian ‐ Amazonian on Mars, persistent or repeated processes permitted habitable surface conditions.
Chemoselective and Enantioselective Hydrogenation of 2,4‐Diaryl‐3H‐benzo[b]azepines Catalyzed by Dendritic Phosphinooxazoline Iridium Complexes
Authors: Miao Tingting , Ma Baode , Ding Ziyuan , Liu Youran , He Yan‐Mei , Fan Qing‐Hua 
Published: April 2017

AbstractAn asymmetric hydrogenation of 2,4‐diaryl‐3H‐benzo[b]azepines, catalyzed by dendritic phosphinooxazoline (PHOX) iridium complexes, has been developed. Only the imine group was reduced, while the C=C bond remained untouched, affording a range of chiral 2,3‐dihydro‐1H‐benzo[b]azepine derivatives with good to excellent enantioselectivity (up to 91 % ee). A slightly positive dendritic effect on catalytic reactivity (up to 10 000 TON) was observed.
Binding CO2 by a Cr8 Metallacrown
Authors: Vitórica‐Yrezábal Iñigo J. , Sava Daniel Florin , Timco Grigore A. , Brown Martyn S. , Savage Mathew , Godfrey Harry G. W. , Moreau Florian , Schröder Martin , Siperstein Flor , Brammer Lee , Yang Sihai , Attfield Martin P. , McDouall Joseph J. W. , Winpenny Richard E. P. 
Published: April 2017

AbstractThe {Cr8} metallacrown [CrF(O2CtBu)2]8, containing a F‐lined internal cavity, shows high selectivity for CO2 over N2. DFT calculations and absorption studies support the multiple binding of F‐groups to the C‐center of CO2 (C⋅⋅⋅F 3.190(9)–3.389(9) Å), as confirmed by single‐crystal X‐ray diffraction.
Uncovering the Atomistic Mechanism for Calcite Step Growth
Authors: De La Pierre Marco , Raiteri Paolo , Stack Andrew G. , Gale Julian D. 
Published: April 2017

AbstractDetermining a complete atomic‐level picture of how minerals grow from aqueous solution remains a challenge as macroscopic rates can be a convolution of many reactions. For the case of calcite (CaCO3) in water, computer simulations have been used to map the complex thermodynamic landscape leading to growth of the two distinct steps, acute and obtuse, on the basal surface. The carbonate ion is found to preferentially adsorb at the upper edge of acute steps while Ca2+ only adsorbs after CO32−. In contrast to the conventional picture, ion pairs prefer to bind at the upper edge of the step with only one ion, at most, coordinated to the step and lower terrace. Migration of the first carbonate ion to a growth site is found to be rate‐limiting for kink nucleation, with this process having a lower activation energy on the obtuse step.
Hydrophobic and tribological behaviors of a poly(p‐phenylene benzobisoxazole) fabric composite reinforced with nano‐TiO2
Authors: Li Deke , Guo Zhiguang 
Published: April 2017

ABSTRACT1H,1H,2H,2H‐Perfluorooctyl trichlorosilane (PFTS) was used to modify TiO2 nanoparticles, and hydrophobic PFTS–TiO2 nanoparticles were obtained by an ultrasonic reaction method. The PFTS–TiO2 surface morphological and hydrophobic properties were analyzed with scanning electron microscopy (SEM), Fourier transform infrared spectrometry, and contact angle (CA) testing. Then, the poly(p‐phenylene benzobisoxazole) fabric–phenolic composite filled with PFTS–TiO2 as a lubricant additive was fabricated by a dip‐coating process. The tribological properties of the composite were investigated, and the wear surface morphology was observed by SEM. The experimental results show that the water CA of the composite filled with PFTS–TiO2 was 158°, and the composite containing 4 wt % PFTS–TiO2 exhibited excellent antifriction and abrasion resistance. The hydrophobic surface of the composite showed excellent durable performance with a static water CA of 126.7° after abrasion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45077.
Depolymerization of PET waste to potentially applicable aromatic amides: Their characterization and DFT study
Authors: Teotia Meenu , Tarannum Nazia , Soni Rakesh Kumar 
Published: April 2017

ABSTRACTPoly(ethylene terephthalate) waste has been depolymerized to a series of potentially applicable aromatic amides through aminolysis with different amines such as methylamine, ethylenediamine, ethanolamine, and butylamine at ambient conditions of temperature and pressure. The amides prepared were characterized by different techniques like Fourier transform infrared (FTIR), UV‐Visible spectroscopy, nuclear magnetic resonance (NMR), elemental analysis, mass spectrometry, powdered X‐ray diffraction (XRD), Raman spectroscopy, and thermal analysis. Further more, an attempt is being made to insight the physical parameters of the aromatic amides using ab initio DFT (Density Functional Theory) study. DFT calculations were performed at Becke's three parameter functional and Lee–Yang–Parr functional (B3LYP) level of calculation with 321‐G basis set. The atomic orbital energy (HOMO and LUMO) and energy gap is also represented. The vibrational frequencies optimized by DFT were in agreement with the experimental FTIR data. An efficient conversion of PET waste to amides was achieved without catalyst through environment friendly clean approach. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45153.