bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positive and negative GPS‐TEC ionospheric storm effects during the extreme space weather event of March 2015 over the Brazilian sector
Authors: Fagundes P. R. , Cardoso F. A. , Fejer B. G. , Venkatesh K. , Ribeiro B. A. G. , Pillat V. G. 
Published: May 2016

AbstractWe studied the response of the ionosphere (F region) in the Brazilian sector during extreme space weather event of 17 March 2015 using a large network of 102 GPS‐ total electron content (TEC) stations. It is observed that the vertical total electron content (VTEC) was severely disturbed during the storm main and recovery phases. A wavelike oscillation with three peaks was observed in the TEC diurnal variation from equator to low latitudes during the storm main phase on 17–18 March 2015. The latitudinal extent of the wavelike oscillation peaks decreased from the beginning of the main phase toward the recovery phase. The first peak extended from beyond 0°S to 30°S, the second occurred from 6°S to 25°S, whereas the third diurnal peaks was confined from 13°S to 25°S. In addition, a strong negative phase in VTEC variations was observed during the recovery phase on 18–19 March 2015. This ionospheric negative phase was stronger at low latitudes than in the equatorial region. Also, two latitudinal chains of GPS‐TEC stations from equatorial region to low latitudes in the east and west Brazilian sectors are used to investigate the storm time behavior of the equatorial ionization anomaly (EIA) in the east and west Brazilian sectors. We observed an anomalous behavior in EIA caused by the wavelike oscillations during the storm main phase on 17 March, and suppression of the EIA, resulting from the negative phase in VTEC, in the storm recovery phase.
Impact of midnight thermosphere dynamics on the equatorial ionospheric vertical drifts
Authors: Fang T.‐W. , Akmaev R. A. , Stoneback R. A. , Fuller‐Rowell T. , Wang H. , Wu F. 
Published: May 2016

AbstractRecent satellite and ground‐based observations have revealed the existence of upward drifts in the postmidnight equatorial ionosphere (~0–3 LT). The phenomenon has not been explained by theoretical models. Simulations using the Whole Atmosphere Model coupled with the Global Ionosphere Plasmasphere model have successfully reproduced the unusual nighttime upward drifts. The simulations and observations by the Ion Velocity Meter onboard the Communications/Navigation Outage Forecasting System also reveal substantial longitudinal dependence of the drifts. Our analysis indicates that the upward drifts are driven by thermosphere dynamics associated with the midnight temperature maximum (MTM). The MTM locally reverses the typical large‐scale zonal and meridional wind pattern, in turn affecting the nighttime F layer electrodynamics. In addition, the longitudinal variation of the drifts in different seasons depends on the magnitude and position of the MTM peak relative to the magnetic equator.
Crude oil jets in crossflow: Effects of dispersant concentration on plume behavior
Authors: Murphy David W. , Xue Xinzhi , Sampath Kaushik , Katz Joseph 
Published: May 2016

AbstractThis study investigates the effects of premixing oil with chemical dispersant at varying concentrations on the flow structure and droplet dynamics within a crude oil jet transitioning into a plume in a crossflow. It is motivated by the need to determine the fate of subsurface oil after a well blowout. The laboratory experiments consist of flow visualizations, in situ measurements of the time evolution of droplet‐size distributions using holography, and particle image velocimetry to characterize dominant flow features. Increasing the dispersant concentration dramatically decreases the droplet sizes and increases their number, and accordingly, reduces the rise rates of droplets and the upper boundary of the plume. The flow within the plume consists primarily of a pair of counterrotating quasi‐streamwise vortices (CVP) that characterize jets in crossflows. It also involves generation of vertical wake vortices that entrain small droplets under the plume. The evolution of plume boundaries is dominated by interactions of droplets with the CVP. The combined effects of vortex‐induced velocity and significant quiescent rise velocity of large (∼5 mm) droplets closely agree with the rise rate of the upper boundary of the crude oil plume. Conversely, the much lower rise velocity of the smaller droplets in oil‐dispersant mixtures results in plume boundaries rising at rates that are very similar to those of the CVP center. The size of droplets trapped by the CVP is predicted correctly using a trapping function, which is based on a balance of forces on a droplet located within a horizontal eddy.
A novel analysis of spring phenological patterns over Europe based on co‐clustering
Authors: Wu Xiaojing , Zurita‐Milla Raul , Kraak Menno‐Jan 
Published: May 2016

AbstractThe study of phenological patterns and their dynamics provides insights into the impacts of climate change on terrestrial ecosystems. Here we present a novel analytical workflow, based on co‐clustering, that enables the concurrent study of spatio‐temporal patterns in spring phenology. The workflow is illustrated with a long‐term time series of first leaf dates (FLD) over Europe, northern Africa, and Turkey calculated using the extended spring index models and the European E‐OBS daily maximum and minimum temperatures (1950 to 2011 with a spatial resolution of 0.25°). This FLD dataset was co‐clustered using the Bregman block average co‐clustering with I‐divergence (BBAC_I), and the results were refined using k‐means. These refined co‐clusters were mapped to provide a first spatially‐continuous delineation of phenoregions in Europe. Our results show that the study area exhibits four main spatial phenological patterns of spring onset. The temporal dynamics of these phenological patterns indicate that the first years of the study period tend to have late spring onsets and the recent years have early spring onsets. Our results also show that the study period exhibits 12 main temporal phenological patterns of spring onset. The spatial distributions of these temporal phenological patterns show that western Turkey tends to have the most variable spring onsets. Changes in the boundaries of other phenoregions can also be observed. These results indicate that this co‐clustering based analytical workflow effectively enables the simultaneous study of both spatial patterns and their temporal dynamics and of temporal patterns and their spatial dynamics in spring phenology.
Shift of the magnetopause reconnection line to the winter hemisphere under southward IMF conditions: Geotail and MMS observations
Authors: Kitamura N. , Hasegawa H. , Saito Y. , Shinohara I. , Yokota S. , Nagai T. , Pollock C. J. , Giles B. L. , Moore T. E. , Dorelli J. C. , Gershman D. J. , Avanov L. A. , Paterson W. R. , Coffey V. N. , Chandler M. O. , Sauvaud J. A. , Lavraud B. , Torbert R. B. , Russell C. T. , Strangeway R. J. , Burch J. L. 
Published: May 2016

AbstractAt 02:13 UT on 18 November 2015 when the geomagnetic dipole was tilted by −27°, the MMS spacecraft observed southward reconnection jets near the subsolar magnetopause under southward and dawnward interplanetary magnetic field conditions. Based on four‐spacecraft estimations of the magnetic field direction near the separatrix and the motion and direction of the current sheet, the location of the reconnection line was estimated to be ~1.8 RE or further northward of MMS. The Geotail spacecraft at GSM Z~1.4 RE also observed southward reconnection jets at the dawnside magnetopause 30–40 min later. The estimated reconnection line location was northward of GSM Z~2 RE. This crossing occurred when MMS observed purely southward magnetic fields in the magnetosheath. The simultaneous observations are thus consistent with the hypothesis that the dayside magnetopause reconnection line shifts from the subsolar point toward the northern (winter) hemisphere due to the effect of geomagnetic dipole tilt.
Substorm onset: A switch on the sequence of transport from decreasing entropy to increasing entropy
Authors: Chen C. X. 
Published: May 2016

AbstractIn this study, we propose a scenario about the trigger for substorm onset. In a stable magnetosphere, entropy is an increasing function tailward. However, in the growth phase of a substorm, a later born bubble has lower entropy than earlier born bubbles. When a bubble arrives at its final destination in the near‐Earth region, it will spread azimuthally because of its relatively uniform entropy. The magnetic flux tubes of a dying bubble, which cause the most equatorward aurora thin arc, would block the later coming bubble tailward of them, forming an unstable domain. Therefore, an interchange instability develops, which leads to the collapse of the unstable domain, followed by the collapse of the stretched plasma sheet. We regard the substorm onset as a switch on the sequence of transport, i.e., from a decreasing entropy process to an increasing entropy process. We calculated the most unstable growth rates and the wavelengths of instability, and both are in agreement with observations.
Alongshore momentum transfer to the nearshore zone from energetic ocean waves generated by passing hurricanes
Authors: Mulligan Ryan P. , Hanson Jeffrey L. 
Published: May 2016

AbstractWave and current measurements from a cross‐shore array of nearshore sensors in Duck, NC, are used to elucidate the balance of alongshore momentum under energetic wave conditions with wide surf zones, generated by passing hurricanes that are close to and far from to the coast. The observations indicate that a distant storm (Hurricane Bill, 2009) with large waves has low variability in directional wave characteristics resulting in alongshore currents that are driven mainly by the changes in wave energy. A storm close to the coast (Hurricane Earl, 2010), with strong local wind stress and combined sea and swell components in wave energy spectra, has high variability in wave direction and wave period that influence wave breaking and nearshore circulation as the storm passes. During both large wave events, the horizontal current shear is strong and radiation stress gradients, bottom stress, wind stress, horizontal mixing, and cross‐shore advection contribute to alongshore momentum at different spatial locations across the nearshore region. Horizontal mixing during Hurricane Earl, estimated from rotational velocities, was particularly strong suggesting that intense eddies were generated by the high horizontal shear from opposing wind‐driven and wave‐driven currents. The results provide insight into the cross‐shore distribution of the alongshore current and the connection between flows inside and outside the surf zone during major storms, indicating that the current shear and mixing at the interface between the surf zone and shallow inner shelf is strongly dependent on the distance from the storm center to the coast.
High‐Mobility Naphthalene Diimide and Selenophene‐Vinylene‐Selenophene‐Based Conjugated Polymer: n‐Channel Organic Field‐Effect Transistors and Structure–Property Relationship
Authors: Sung Min Jae , Luzio Alessandro , Park Won‐Tae , Kim Ran , Gann Eliot , Maddalena Francesco , Pace Giuseppina , Xu Yong , Natali Dario , de Falco Carlo , Dang Long , McNeill Christopher R. , Caironi Mario , Noh Yong‐Young , Kim Yun‐Hi 
Published: May 2016

Interdependence of chemical structure, thin‐film morphology, and transport properties is a key, yet often elusive aspect characterizing the design and development of high‐mobility, solution‐processed polymers for large‐area and flexible electronics applications. There is a specific need to achieve >1 cm2 V−1 s−1 field‐effect mobilities (μ) at low processing temperatures in combination with environmental stability, especially in the case of electron‐transporting polymers, which are still lagging behind hole transporting materials. Here, the synthesis of a naphthalene‐diimide based donor–acceptor copolymer characterized by a selenophene vinylene selenophene donor moiety is reported. Optimized field‐effect transistors show maximum μ of 2.4 cm2 V−1 s−1 and promising ambient stability. A very marked film structural evolution is revealed with increasing annealing temperature, with evidence of a remarkable 3D crystallinity above 180 °C. Conversely, transport properties are found to be substantially optimized at 150 °C, with limited gain at higher temperature. This discrepancy is rationalized by the presence of a surface‐segregated prevalently edge‐on packed polymer phase, dominating the device accumulated channel. This study therefore serves the purpose of presenting a promising, high‐electron‐mobility copolymer that is processable at relatively low temperatures, and of clearly highlighting the necessity of specifically investigating channel morphology in assessing the structure–property nexus in semiconducting polymer thin films.
π–π Interactions: Influence on Molecular Packing and Solid‐State Emission of ESIPT and non‐ESIPT Motifs
Authors: Padalkar Vikas S. , Sakamaki Daisuke , Kuwada Kenji , Horio Akifumi , Okamoto Haruka , Tohnai Norimitsu , Akutagawa Tomoyuki , Sakai Ken‐ichi , Seki Shu 
Published: May 2016

AbstractNovel, triphenylamino benzothiazole‐based excited‐state intramolecular proton transfer (ESIPT) and non‐ESIPT fluorophores were prepared by Suzuki coupling reactions. Their photophysical properties in solution, aqueous suspension, and in the solid state were systematically investigated. High fluorescence quantum efficiencies (Φsol≈95 %; Φsolid≈88 %), moderate Stokes shifts (≈8000 cm−1), microenvironment‐sensitive and molecular‐framework‐dependent emission are the striking features of the protocol described here. Solid‐state emission was modulated and interpreted as a crossover effect of π–π interactions using single‐crystal X‐ray analyses. The nonplanar/twisted framework of the system helps to avoid noncovalent interactions, facilitating the suppression of fluorescence quenching in the solid state with high quantum efficiency over 88 %.
Rapid degradation of contaminated soil with 2‐methylpropane‐2‐thiol by H2O2/KMnO4/NaClO system: process modeling and optimization
Authors: Roohi Pejman , Fatehifar Esmaeil , Alizadeh Reza 
Published: May 2016

Abstract2‐Methylpropane‐2‐thiol is a hazardous material, and remediation of soil polluted by this contaminant with a fast method is important to study.In this study, H2O2/KMnO4/NaClO system as a combined system is investigated for 2‐methylpropane‐2‐thiol oxidation because of especial characteristics of each oxidation agent. Central composite design based on response surface methodology was used to obtain appropriate effects of the main factors (initial oxidant concentrations and FeSO4 to soil ratio) and their interactions on the removal efficiency. Pareto analysis show that initial H2O2 concentration, FeSO4 to soil ratio, initial NaClO concentration, and interaction between H2O2 and FeSO4 are the most influential factors on 2‐methylpropane‐2‐thiol removal efficiency (31.82%, 16.85%, 16.24%, and 8.62% respectively). P‐value of lack‐of‐fit (0.621) indicates that suggested model adequately fits the data with high correlation coefficient (R2 = 97.59%). Investigation of optimum condition suggests that interaction of KMnO4 with H2O2 drops the removal efficiency and its concentration has to be as low as possible. The concentration of other studied oxidation agents and Fe2+ ion must be as high as possible in the studied intervals. Verification experiment at optimum condition shows 95.71% for maximum 2‐methylpropane‐2‐thiol removal efficiency that is a good agreement with the predicted value (94.76%). © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Sustainable biobased blends from the reactive extrusion of polylactide and acrylonitrile butadiene styrene
Authors: Vadori Ryan , Misra Manjusri , Mohanty Amar K. 
Published: May 2016

ABSTRACTPolymer blends containing poly(lactic acid) (PLA) and acrylonitrile butadiene styrene (ABS) with high biobased content (50%) were made by extrusion and injection molding. Two additives, one acrylic copolymer and one chain extender were used separately and in combination to increase mechanical properties. Interestingly, the combination of both the acrylic copolymer and chain extender worked to synergistically increase the impact strength by almost 600%. This was attributed to the complementary additive toughening effects which allowed increased energy dissipation of the blend at high speed testing, such as in the impact test. Morphology and rheology investigation showed that the two additives worked together to vastly change the dispersion and phase sizes, suggesting a decreased tension between the PLA and ABS. Finally, Fourier transform infrared spectroscopy supported the evidence that the epoxy groups of the chain extender undergo ring opening to react with the functional groups of the PLA. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43771.
Microfibrillated cellulose‐reinforced nonedible starch‐based thermoset biocomposites
Authors: Patil Namrata V. , Netravali Anil N. 
Published: May 2016

ABSTRACTThe present research focuses on developing nonedible starch‐based resin to replace the currently used edible starches (corn, potato, etc.), protein (soy) as well as some of the petroleum‐based resins for fiber‐reinforced composite applications. Starch was extracted from mango seeds, a waste source freely available in tropical countries. Micro fibrillated cellulose (MFC) obtained from kraft pulp was used to reinforce mango seed starch‐based resin in order to take advantage of the chemical similarity between the starch and the cellulose which results in good interfacial bonding. Uniform dispersion of MFC in starch was obtained using homogenizer. Further, this MFC/MSS mixture was crosslinked using an environment friendly crosslinker, 1,2,3,4‐butane tetracarboxylic acid (BTCA). Crosslinking was confirmed directly using ATR‐FTIR spectra. MFC/MSS biocomposite specimens were prepared by solution casting method. The characterization of MFC/MSS biocomposites showed that their tensile and thermal properties were comparable to the edible starch‐based composites. The thermoset resins obtained from agricultural mango seed waste can be used to replace currently available resins derived from the edible sources or even some petroleum‐based resins for packaging, coatings, mulches, and other applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43803.
Characterization of nanocomposite resol resins: Individual/synergist effects of alendronic acid and sepiolite
Authors: Alkan Ümran Burcu , Kızılcan Nilgün 
Published: May 2016

ABSTRACTAlendronic acid modified resol nanocomposite resins (AA‐PFNCRs) and sepiolite modified resol nanocomposite resins (SEP‐PFNCRs) have been synthesized by in situ method in the presence of base catalyst. Additionally, the synergistic effects of alendronic acid and sepiolite clay (AA‐SEP‐PFNCR) on the resol resin have been studied. The structure, morphology, and thermal properties of these nanocomposites have been investigated by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and X‐ray Diffraction (XRD). The results demonstrated the interactions between the fillers and resol resin. Thermal properties of nanocomposite resins were improved due to alendronic acid and sepiolite. The obtained samples were also characterized morphologically by Scanning Electron Microscope (SEM). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43807.
Improvement of the impact strength of ethylene‐propylene random copolymers by nucleation
Authors: Horváth Zsuzsanna , Menyhárd Alfréd , Doshev Petar , Gahleitner Markus , Friel David , Varga József , Pukánszky Béla 
Published: May 2016

ABSTRACTFive ethylene‐propylene random copolymers were nucleated with two soluble nucleating agents. Ethylene content changed between 1.7 and 5.3 wt %, while nucleating agent content was adjusted according to the solubility of the additive. It changed from 0 to 5000 ppm for the sorbitol (1,2,3‐tridesoxy‐4,6:5,7‐bis‐O‐[(4‐propylphenyl) methylene]‐nonitol) and from 0 to 500 ppm for the trisamide compound (1,3,5‐benzene‐trisamide) used. Crystalline structure was analyzed in detail by various methods (DSC, XRD, and SEM). Mechanical properties were characterized by tensile and instrumented impact measurements. The results showed that most properties changed moderately upon nucleation, but impact resistance increased considerably. Spherulitic structure was not detected, but instead in the presence of the soluble nucleating agents used a microcrystalline structure formed. The large increase of impact resistance could not be related directly to changes in crystalline morphology. On the other hand, local rearrangement of morphology was detected by XRD and SEM analysis including an increase of lamella thickness, crystal orientation, and the formation of shish‐kebab structures in the core of the injection molded specimens. A small increase in the γ‐phase content of PP was also observed. These changes increased crack propagation energy considerably leading to the large improvement observed in impact resistance. Although the phenomenon could be related to ethylene content, differences in molecular weight also helped to explain the changes observed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43823.
Silicified microcrystalline cellulose based pellets and their physicochemical properties
Authors: Mustafa Oluwabukola , Chaw Cheng Shu 
Published: May 2016

ABSTRACTSilicified microcrystalline cellulose (SMCC), Prosolv SMCC 50 was used as spheronization aid to manufacture pellets by extrusion and spheronization. Different ratios of SMCC to lactose were used to manufacture pellets using appropriate levels of water as liquid binder. Avicel PH101 based pellets were also manufactured for comparison of their physical properties. The ratio of liquid binder to spheronization aid was critical to produce pellets of desired size and shape. Extrudates composed of 20% aid could withstand only smaller spheronization force in order to be shaped into pellets. The successful products fulfilled the quality of pellets such as narrow size distribution and spherical in shape. The highest surface tensile strength was observed in pellets with equal ratio of lactose to SMCC while pellets having 20% aid disintegrated rapidly within 15 min. Furthermore, Prosolv SMCC 50 based pellets possessed a stronger surface tensile strength when compared with Avicel PH101 based pellets. In conclusion, Prosolv SMCC 50 has showed to be a good spheronization aid for extrusion and spheronization when used in the range of 20 to 80% content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43829.
Preparation and properties of a form‐stable phase‐change hydrogel for thermal energy storage
Authors: Wang Tao , Wu Nan , Li Hui , Lu Qu‐Liang , Jiang Yong 
Published: May 2016

ABSTRACTIn this study, we aimed to fabricate a form‐stable phase‐change hydrogel (PCH) with excellent mechanical properties and heat‐storage properties. Sodium alginate (SA) and polyacrylamide (PAAm) composite hydrogels were prepared with ionically crosslinked SA in a PAAm hydrogel network. Glauber's salt [i.e., sodium sulfate decahydrate (Na2SO4·10H2O)] was incorporated within the hydrogel network as a phase‐change material. Scanning electron microscopy micrographs revealed that Na2SO4·10H2O was confined in the micropores of the hydrogel inner spaces, and differential scanning calorimetry curves showed that the composite hydrogel possessed a considerable storage potential. Mechanical properties tests, such as tensile and compressive measurements, presented a decreasing trend with increasing Na2SO4·10H2O dosage. We concluded that the prepared composite PCH could be used to design hydrogel materials with thermal‐energy‐storage applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43836.