bluuebunny/crossref_metadata_2025_split huggingface dataset:
New insights into the wind‐dust relationship in sandblasting and direct aerodynamic entrainment from wind tunnel experiments
Authors: Parajuli Sagar Prasad , Zobeck Ted M. , Kocurek Gary , Yang Zong‐Liang , Stenchikov Georgiy L. 
Published: January 2016

AbstractNumerous parameterizations have been developed for predicting wind erosion, yet the physical mechanism of dust emission is not fully understood. Sandblasting is thought to be the primary mechanism, but recent studies suggest that dust emission by direct aerodynamic entrainment can be significant under certain conditions. In this work, using wind tunnel experiments, we investigated some of the lesser understood aspects of dust emission in sandblasting and aerodynamic entrainment for three soil types, namely, clay, silty clay loam, and clay loam. First, we explored the role of erodible surface roughness on dust emitted by aerodynamic entrainment. Second, we compared the emitted dust concentration in sandblasting and aerodynamic entrainment under a range of wind friction velocities. Finally, we explored the sensitivity of emitted dust particle size distribution (PSD) to soil type and wind friction velocity in these two processes. The dust concentration in aerodynamic entrainment showed strong positive correlation, no significant correlation, and weak negative correlation, for the clay, silty clay loam, and clay loam, respectively, with the erodible soil surface roughness. The dust in aerodynamic entrainment was significant constituting up to 28.3, 41.4, and 146.4% compared to sandblasting for the clay, silty clay loam, and clay loam, respectively. PSD of emitted dust was sensitive to soil type in both sandblasting and aerodynamic entrainment. PSD was sensitive to the friction velocity in aerodynamic entrainment but not in sandblasting. Our results highlight the need to consider the details of sandblasting and direct aerodynamic entrainment processes in parameterizing dust emission in global/regional climate models.
Global carbon cycle perturbation across the Eocene‐Oligocene climate transition
Authors: Armstrong McKay David I. , Tyrrell Toby , Wilson Paul A. 
Published: January 2016

AbstractThe Eocene‐Oligocene transition (EOT), ~34 Ma, marks a tipping point in the long‐term Cenozoic greenhouse to icehouse climate transition. Paleorecords reveal stepwise rapid cooling and ice growth across the EOT tightly coupled to a transient benthic δ13C excursion and a major and permanent deepening of the carbonate compensation depth (CCD). Based on biogeochemical box modeling, Merico et al. (2008) suggested that a combination of (1) glacioeustatic sea level fall‐induced shelf‐basin carbonate burial fractionation and (2) shelf carbonate weathering can account for the carbon cycle perturbation, but this finding has been questioned. Alternative proposed mechanisms include increased ocean ventilation, decreased carbonate burial, increased organic carbon burial, increased silicate weathering, and increased ocean calcium concentration. Here we use an improved version of the biogeochemical box model of Merico et al. (2008) to reevaluate these competing hypotheses and an additional mechanism, the expansion of “carbon capacitors” such as permafrost and peatlands. We find that changes in calcium concentration, silicate weathering, and carbonate or organic carbon burial each yield a response that is fundamentally at odds with the form and/or sign of the paleorecords. Shelf‐basin carbonate burial fractionation (CCD change), plus shelf carbonate weathering, sequestration of 12C‐enriched carbon into carbon capacitors, and possibly increased ocean ventilation (δ13C excursion), offers the best fit to the paleorecords. Further work is needed to understand why the EOT carbon cycle perturbation is so unique when the forcing mechanisms hypothesized to be responsible (cooling and ice growth) are not peculiar to this event.
Southwest Pacific Ocean surface reservoir ages since the last glaciation: Circulation insights from multiple‐core studies
Authors: Sikes Elisabeth L. , Guilderson Thomas P. 
Published: January 2016

AbstractRadiocarbon (14C) in dissolved inorganic carbon in the ocean can trace the age of ocean water relative to the atmosphere and provide insight into climate‐driven changes in ocean circulation since the last glaciation. Here we estimate surface radiocarbon ages from the last glaciation through the deglaciation into the Holocene in the southwestern Pacific by using tephras, both as stratigraphic tie points and for the availability of existing radiocarbon dates from terrestrial‐ based analyses of the organic carbon associated with them, as markers of past atmospheric Δ14C. The glacial surface reservoir age of subtropical waters was ~700 14C years older than the coeval atmosphere at ~25,000 cal yr B.P. This was significantly older (more 14C depleted) by ~ 300 14C years, than modern reservoir ages. At the same time, subantarctic surface water reservoir age was ~3200 14C years, almost 5 times the modern reservoir age, making the difference in age between subtropical and subantarctic surface water masses treble the modern difference. This pattern is attributed to the upwelling and exchange of very old deep waters from the glacial abyss in the Southern Ocean. In the early deglaciation, surface reservoir ages were ~600 to 700 14C years. Recent atmospheric Δ14C calibrations project that these surface reservoir ages were older than modern by 1.2‐fold to 2‐fold. This increased reservoir effect can be attributed to shallow circulation that differed from modern, delivering waters with lower 14C content to the region. Early Holocene surface reservoir ages of ~300 to 500 14C years, similar to recent, suggest modern circulation patterns were in place by that time.
Influence of particle size and density, and channel velocity on the deposition patterns around a circular patch of model emergent vegetation
Authors: Shi Ying , Jiang Beihan , Nepf Heidi M. 
Published: January 2016

AbstractThis laboratory study examined the influence of particle size and density, and channel velocity on the spatial deposition pattern around an emergent (extending through the entire water depth), circular patch of model vegetation located at the center of a channel. Three flow conditions and three particles of different size and density were considered. Across all particle and velocity conditions, three basic deposition patterns were observed: (1) high deposition in the patch wake and low deposition in the zones adjacent to the patch; (2) high deposition in both the wake and adjacent zones; and (3) low deposition in both the wake and adjacent zones. The observed deposition pattern correlated with the ratio of channel shear velocity (
to critical shear velocity (
Specifically, for
or
, the deposition was high (or low, respectively) over the entire channel with little difference between the wake and adjacent regions. In contrast, for
divergence in net deposition between the wake and the adjacent zones occurred, with higher net deposition in the wake and lower net deposition in the adjacent zones. The peak divergence was observed at
. The deposition patterns were more closely correlated with the ratio
than with
(with
the particle settling velocity), suggesting that the spatial variation in net deposition was driven by resuspension (associated with
) and not settling (associated with
).
Intense low‐frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons
Authors: Gao Zhonglei , Su Zhenpeng , Zhu Hui , Xiao Fuliang , Zheng Huinan , Wang Yuming , Shen Chao , Wang Shui 
Published: January 2016

AbstractFrequency distribution is a vital factor in determining the contribution of whistler mode chorus to radiation belt electron dynamics. Chorus is usually considered to occur in the frequency range 0.1–0.8fce_eq (with the equatorial electron gyrofrequency fce_eq). We here report an event of intense low‐frequency chorus with nearly half of wave power distributed below 0.1fce_eq observed by Van Allen Probe A on 27 August 2014. This emission propagated quasi‐parallel to the magnetic field and exhibited hiss‐like signatures most of the time. The low‐frequency chorus can produce the rapid loss of low‐energy (∼0.1 MeV) electrons, different from the normal chorus. For high‐energy (≥0.5 MeV) electrons, the low‐frequency chorus can yield comparable momentum diffusion to that of the normal chorus but much stronger (up to 2 orders of magnitude) pitch angle diffusion near the loss cone.
Ductile tear behavior of multilayered polypropylene homopolymer/ethylene 1‐octene copolymer sheets
Authors: He Guansong , Zhang Fengshun , Yu Huaning , Li Jiang , Guo Shaoyun 
Published: January 2016

ABSTRACTThe tear resistance of the polypropylene homopolymer (HPP)/ethylene 1‐octene copolymer (POE) alternating multilayered sheets, which were prepared through multilayered coextrusion, was evaluated. Polarized optical microscope (POM) photographs revealed that HPP and POE layers aligned alternately vertical to the interfaces and continuously parallel to the extrusion direction. Tear results demonstrated the conventional blends had less tear‐resistant than the multilayered samples. Large plastic deformation of HPP layer occurred in the multilayered structure during the stable crack growth, causing the tear energy to increase with the number of layers increasing. The measurements of PCMW2D IR and WAXD revealed that the large plastic deformation had a direct relationship with the crystal structure and termination of micro‐cracks by interface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43298.
Improvement of the mechanical behavior of bioplastic poly(lactic acid)/polyamide blends by reactive compatibilization
Authors: Gug JeongIn , Sobkowicz Margaret J. 
Published: January 2016

ABSTRACTPolymer blends are of significant interest for reinforcing bioplastics via addition of a second polymer and a blend compatibilizer or in situ reaction. However, increased costs associated with additional materials and extra processing steps can limit the viability of this solution. Here, a simple, continuous reactive extrusion processing method was examined for producing tougher bioplastic blends. p‐Toluenesulfonic acid (TsOH) catalyst was added to two immiscible biobased polymers, poly(lactic acid) (PLA) and polyamide11 (PA11), to induce ester‐amide exchange reaction. The mechanical properties of PLA were improved through mixing with PA11 by introducing copolymers at the interface thereby reducing interfacial tension. The morphology, chemical structure analysis, and tensile testing supported that copolymerization reaction occurred resulting in improved bonding between PLA and PA11 with 0.5 wt % TsOH catalyst in the batch mixing, but depolymerization dominated at higher shear stress (2000 rpm) and catalyst loading (over 2 wt %). The PLA/PA11 blend with 0.5 wt % TsOH catalyst displayed around 50% improvement in elongation at break in twin‐screw extruder blending (around 5 min mixing time) at 250 rpm screw speed, which was similar to the improvement using batch mixing (20 min mixing time). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43350.
Use of polyethylene films photografted with 2‐(dimethylamino)ethyl methacrylate as a potential adsorbent for removal of chromium (VI) from aqueous medium
Authors: Asamoto Hiromichi , Kimura Yuji , Ishiguro Yohei , Minamisawa Hiroaki , Yamada Kazunori 
Published: January 2016

ABSTRACTA new polymeric adsorbent material based on polyethylene (PE) was prepared by photografting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) as a positively chargeable monomer to a PE film. The effects of the experimental parameters, such as the pH value, temperature, and grafted amount on adsorption of chromium(VI) (Cr(VI)) ions were investigated for the DMAEMA‐grafted PE (PE‐g‐PDAMEMA) films. The maximum adsorption capacity was obtained at the initial pH value of 3.0 for a PE‐g‐PDMAEMA film with 1.8 mmol/g and the maximum adsorption capacity obtained was higher than or compatible to those of many of the other polymeric adsorbents prepared for Cr(VI) ions. The adsorption kinetics obeyed the mechanism of the pseudo‐second order kinetic model and adsorption of Cr(VI) ions on PE‐g‐PDMAEMA films was well expressed by the Langmuir isotherm model. A high Langmuir adsorption constant suggests that the adsorption of Cr(VI) ions occurs between protonated dimethylamino groups and
ions mainly through the electrostatic interaction. Cr(VI) ions adsorbed were successfully desorbed from a PE‐g‐PDMAEMA film in solutions of NaCl, NH4Cl, NH4Cl containing NaOH, and NaOH and a PE‐g‐PDMAEMA film was regenerated and repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43360.
Micromechanical modeling of roll‐to‐roll processing of oriented polyethylene terephthalate films
Authors: Poluektov M. , van Dommelen J. A. W. , Govaert L. E. , MacKerron D. H. , Geers M. G. D. 
Published: January 2016

ABSTRACTIn this article, the thermo‐mechanical time‐dependent behavior of oriented polyethylene terephthalate (PET) films, which are used as a substrate material for flexible Organic Light‐Emitting Diode (OLED)s, is analyzed. These films are subjected to conditions that are representative for the industrial manufacturing process. Effects of creep and thermal shrinkage are experimentally observed simultaneously. The aim of the article is to demonstrate the ability of the micromechanically‐based model, which was previously used to separately describe both creep and thermal shrinkage of the polyethylene terephthalate film, to simulate experimentally observed anisotropic behavior of the film under complex loading conditions. This anisotropic behavior results from the microstructure, the internal stress state, and differences in constitutive behavior of the phases. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43384.
Polyimide‐based porous hollow carbon nanofibers for supercapacitor electrode
Authors: Le Trung Hieu , Yang Ying , Yu Liu , Gao Tianji , Huang Zhenghong , Kang Feiyu 
Published: January 2016

ABSTRACTPorous hollow carbon nanofibers (PHCNFs) using styrene‐acrylonitrile copolymer (SAN) solution as core and polyacrylic acid (PAA) as shell were manufactured by co‐axial electrospinning technique, taking polyvinyl pyrrolidone (PVP) as a pore inducer additive in the shell. The shell thickness of PHCNFs could be adjusted by controlling flow rates of core and shell fluids. The prepared PHCNFs showed excellent electrochemical properties with the high specific capacitance of 221 F g−1 and superior cycling stability, remaining a capacitance retention of 95% after 5000 cycles under a scan rate of 0.1 V s−1. In this system, hollow structures bring a 20% capacitance improvement, while the porous morphology brings a 47% capacitance improvement. The attractive performances exhibited by these sponge supercapacitors make them potentially promising candidates for future energy storage systems. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43397.
The preparation of SPEEK/phosphate salts membranes and application for CO2/CH4 separation
Authors: Lv Jianfei , Liu Yuanyuan , Qin Yun , Guo Ruili , Zhang Jianshu , Wei Zhong 
Published: January 2016

ABSTRACTSPEEK/phosphate salts membranes were prepared and utilized for CO2/CH4 separation. SPEEK with abundant –SO3H groups and EO groups on polymer chains would be beneficial for CO2 transport. The doped phosphate salts (NaH2PO4, Na2HPO4 and Na3PO4) with different acid‐base properties increased the water content in the membrane, and water was expected to increase both the solubility and diffusivity of CO2 in the membrane. All membranes were characterized by FTIR, TGA, and XRD. The CO2 permeability and CO2/CH4 selectivity of SPEEK/Na3PO4 membranes were higher than that of SPEEK/NaH2PO4 and SPEEK/Na2HPO4 membranes. Compared to the pure SPEEK membrane, the CO2 permeability and CO2/CH4 selectivity of SPEEK/Na3PO4−10 membrane were increased by 144% and 65%, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43399.
Novel floating photocatalysts based on polyurethane composite foams modified with silver/titanium dioxide/graphene ternary nanoparticles for the visible‐light‐mediated remediation of diesel‐polluted surface water
Authors: Ni Lingfeng , Li Yi , Zhang Chi , Li Linze , Zhang Wenlong , Wang Dawei 
Published: January 2016

ABSTRACTPhotocatalyst loading on a floating substitute is accepted as a promising method for the remediation of diesel‐polluted surface water. Therefore, novel photocatalysts based on polyurethane foams modified with silver/titanium dioxide/graphene ternary nanoparticles (PU–Ag/P25/G) were synthesized and investigated. Scanning electron microscopy, energy‐dispersive X‐ray spectrometry, X‐ray diffraction, Fourier transform infrared spectroscopy, and UV–visible spectroscopy showed the coexistence of Ag, Degussa P25 (P25), and graphene and the nanoscale dispersion of nanoparticles in the matrix and on the surface of the polyurethane (PU) foam. The diesel adsorption capacity of the photocatalyst reached 96 g/g. The maximum diesel degradation was found to be 76% in a period of 16 h. Compared with polyurethane‐foam‐supported P25/graphene (PU–P25/G) and polyurethane‐foam‐supported P25 (PU–P25), all of the adsorption isotherm and degradation kinetics followed the order PU–Ag/P25/G > PU–P25/G > PU–P25 > PU; this was due to the loading of different nanoparticles. Moreover, the degradation efficiency was reduced only 5% after five consecutive reactions; this showed good stability and reusability of the photocatalyst for surface water restoration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43400.
Unusual poly(3‐hydroxyalkanoate) (PHA) biosynthesis behavior of Pseudomonas putida Bet001 and Delftia tsuruhatensis Bet002 isolated from palm oil mill effluent
Authors: Razaif‐Mazinah Mohd Rafais Mohd , Anis Siti Nor Syairah , Harun Hazwani Izzati , Rashid Khairunnisa Abdul , Annuar Mohamad Suffian Mohamad 
Published: January 2016

AbstractPseudomonas putida Bet001 and Delftia tsuruhatensis Bet002, isolated from palm oil mill effluent, accumulated poly(3‐hydroxyalkanoates) (PHAs) when grown on aliphatic fatty acids, sugars, and glycerol. The substrates were supplied at 20:1 C/N mole ratio. Among C‐even n‐alkanoic acids, myristic acid gave the highest PHA content 26 and 28 wt% in P. putida and D. tsuruhatensis, respectively. Among C‐odd n‐alkanoic acids, undecanoic gave the highest PHA content at 40 wt% in P. putida and 46 wt% in D. tsuruhatensis on pentadecanoic acid. Sugar and glycerol gave <10 wt% of PHA content for both bacteria. Interestingly, D. tsuruhatensis accumulated both short‐ and medium‐chain length PHA when supplied with n‐alkanoic acids ranging from octanoic to lauric, sucrose, and glycerol with 3‐hydroxybutyrate as the major monomer unit. In P. putida, the major hydroxyalkanoates unit was 3‐hydroxyoctanoate and 3‐hydroxydecanoate when grown on C‐even acids. Conversely, 3‐hydroxyheptanoate, 3‐hydrxoynonanoate, and 3‐hydroxyundecanoate were accumulated with C‐odd acids. Weight‐averaged molecular weight (Mw) was in the range of 53–81 kDa and 107–415 kDa for P. putida and D. tsuruhatensis, respectively. Calorimetric analyses indicated that both bacteria synthesized semicrystalline polymer with good thermal stability with degradation temperature (Td) ranging from 178 to 282 °C.
Prediction of functionally significant single nucleotide polymorphisms inPTENtumor suppressor gene: Anin silicoapproach
Authors: Khan Imran , Ansari Irfan A. , Singh Pratichi , Dass J Febin Prabhu 
Published: January 2016

AbstractThe phosphatase and tensin homolog (PTEN) gene plays a crucial role in signal transduction by negatively regulating the PI3K signaling pathway. It is the most frequent mutated gene in many human‐related cancers. Considering its critical role, a functional analysis of missense mutations ofPTENgene was undertaken in this study. Thirty five nonsynonymous single nucleotide polymorphisms (nsSNPs) within the coding region of thePTENgene were selected for ourin silicoinvestigation, and five nsSNPs (G129E, C124R, D252G, H61D, and R130G) were found to be deleterious based on combinatorial predictions of different computational tools. Moreover, molecular dynamics (MD) simulation was performed to investigate the conformational variation between native and all the five mutantPTENproteins having predicted deleterious nsSNPs. The results of MD simulation of all mutant models illustrated variation in structural attributes such as root‐mean‐square deviation, root‐mean‐square fluctuation, radius of gyration, and total energy; which depicts the structural stability ofPTENprotein. Furthermore, mutantPTENprotein structures also showed a significant variation in the solvent accessible surface area and hydrogen bond frequencies from the nativePTENstructure. In conclusion, results of this study have established the deleterious effect of the all the five predicted nsSNPs on thePTENprotein structure. Thus, results of the current study can pave a new platform to sort out nsSNPs that can be undertaken for the confirmation of their phenotype and their correlation with diseased status in case of control studies.
Conformational studies on peptides having dipropylglycine (Dpg) or 1‐aminocycloheptanecarboxylic acid (Ac7c) within the sequence of l‐leucine (Leu) residues
Authors: Oba Makoto , Nonaka Hikaru , Doi Mitsunobu , Tanaka Masakazu 
Published: January 2016

ABSTRACTA conformational analysis of peptides having dipropylglycine (Dpg) or 1‐aminocycloheptanecarboxylic acid (Ac7c) within l‐leucine (Leu) residues was conducted in solution and in a crystal state. Dpg and Ac7c had similar structures with acyclic and cyclic side chains, respectively. FTIR, 1H NMR, and CD spectra measurements revealed that the preferred conformations of Dpg‐ and Ac7c‐containing l‐Leu peptides in solution were similar; both had a right‐handed (P) 310‐helix. The Dpg‐containing octapeptide adopted a right‐handed (P) α‐helix in the crystal state. Dpg and Ac7c homopeptides had planar and helical structures as their preferred conformations, respectively; however, Dpg‐ and Ac7c‐containing l‐Leu peptides adopted similar structures in solution. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 210–218, 2016.
Incorporating modeling and simulations in undergraduate biophysical chemistry course to promote understanding of structure‐dynamics‐function relationships in proteins
Authors: Hati Sanchita , Bhattacharyya Sudeep 
Published: January 2016

AbstractA project‐based biophysical chemistry laboratory course, which is offered to the biochemistry and molecular biology majors in their senior year, is described. In this course, the classroom study of the structure‐function of biomolecules is integrated with the discovery‐guided laboratory study of these molecules using computer modeling and simulations. In particular, modern computational tools are employed to elucidate the relationship between structure, dynamics, and function in proteins. Computer‐based laboratory protocols that we introduced in three modules allow students to visualize the secondary, super‐secondary, and tertiary structures of proteins, analyze non‐covalent interactions in protein–ligand complexes, develop three‐dimensional structural models (homology model) for new protein sequences and evaluate their structural qualities, and study proteins' intrinsic dynamics to understand their functions. In the fourth module, students are assigned to an authentic research problem, where they apply their laboratory skills (acquired in modules 1–3) to answer conceptual biophysical questions. Through this process, students gain in‐depth understanding of protein dynamics—the missing link between structure and function. Additionally, the requirement of term papers sharpens students' writing and communication skills. Finally, these projects result in new findings that are communicated in peer‐reviewed journals. © 2016 by The International Union of Biochemistry and Molecular Biology, 44:140–159, 2016.