bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of gas phase hydrochloric acid in the polluted marine boundary layer
Authors: Crisp Timia A. , Lerner Brian M. , Williams Eric J. , Quinn Patricia K. , Bates Timothy S. , Bertram Timothy H. 
Published: May 2014

AbstractShip‐based measurements of gas phase hydrochloric acid (HCl), particulate chloride (pCl−), and reactive nitrogen oxides (NOy) were made in the polluted marine boundary layer along the California coastline during spring 2010. These observations are used to assess both the rate of Cl atom production from HCl and the role of direct HCl emissions and subsequent partitioning as a source for pCl−. Observations of HCl made in coastal Southern California are broadly correlated with NOz (NOz ≡ NOy – NOx), peaking at 11 A.M. The observed median HCl mixing ratio in Southern California is 1.3 ppb (interquartile range: 0.53–2.7 ppb), as compared to 0.19 ppb (interquartile range: 0.10–0.38 ppb) measured along the Sacramento River between San Francisco and Sacramento. Concurrent measurements of aerosol ion chemistry indicate that aerosol particles sampled in Northern California are heavily depleted in Cl−, corresponding to a mean pCl− deficit of 0.05 ± 0.03 (1σ) ppb for sub‐10 µm aerosol particles. In comparison, aerosols measured in Southern California indicate that over 25% of particles showed an addition of Cl− to the particle population. Observations presented here suggest that primary sources of HCl, or gas phase chlorine precursors to HCl, are likely underestimated in the California Air Resource Board emissions inventory. These results highlight the need for future field observations designed to better constrain direct reactive halogen emissions.
Theoretical and numerical analysis of radiation belt electron precipitation by coherent whistler mode waves
Authors: Harid V. , Gołkowski M. , Bell T. , Inan U. S. 
Published: May 2014

AbstractThe interaction between coherent whistler mode waves and energetic radiation belt electrons can result in pitch angle scattering of electrons into the bounce loss cone and subsequent precipitation. In studying the effects of VLF transmitter signals on particle precipitation, past modeling efforts have focused on the computation of diffusion coefficients for a Fokker‐Planck model. In contrast, to capture the nonlinear effects of large‐amplitude coherent waves, we evaluate particle precipitation using a Vlasov‐Liouville (VL) model which computes the phase space particle distribution function directly using a characteristic‐based solution of the Vlasov equation. Previous work has shown that in the case of large‐amplitude coherent waves, phase trapping can significantly perturb resonant particles from their adiabatic paths. We evaluate the importance of phase trapping over a range of wave amplitudes (up to 200 pT); the percentage of particles that precipitate after being phase trapped is computed over a phase space grid in the loss cone. The results demonstrate that phase trapping contributes significantly to precipitation when a large‐amplitude wave (>100 pT) is present. Additionally, linear theory can be valid over a broad range of amplitudes and the relative accuracy of linear theory in calculating the precipitated flux depends strongly on the initial particle distribution. Additionally, we demonstrate the ability of the VL model to calculate the time evolution of the precipitated flux due to short‐duration whistler mode pulses. The physical parameters used in this study are typical of those associated with the Siple Station wave injection experiment.
Pulsating nighttime magnetic background noise in the upper ULF band at low latitudes
Authors: Bösinger T. , Demekhov A. G. , Ermakova E. N. , Haldoupis C. , Zhou Q. 
Published: May 2014

AbstractWe model long‐period (~2 h) irregular pulsations in the ellipticity of magnetic background noise (MBN) in the upper ULF band which were frequently observed during nighttime at a low‐latitude site on the Island of Crete. It is shown that such pulsations cannot be reproduced in the calculations when using the ionosphere parameters from the statistical IRI (International Reference Ionosphere) model, while regular diurnal signatures of the ellipticity spectrum at sunset and sunrise are successfully reproduced. We apply the same approach to the location of the Arecibo incoherent scatter radar and show that using actually measured ionosphere profiles (up to a height of 400 km) instead of IRI profiles produces the ellipticity pulsations very similar to those observed at Crete. Comparison of model results with the calculated behavior of Alfvén mode refractive index allows us to conclude that the observed nighttime long‐period irregular pulsations in the MBN ellipticity are caused by dynamic processes at the upper boundary of the ionospheric E‐F valley which serves as a subionospheric Alfvén resonator. Irregular widening, shrinking, and/or deepening of the valley with time scales of 1 to 4 h affect the electrodynamical properties of this resonator and manifest themselves in the magnetic background noise properties.
EMHD theory and observations of electron solitary waves in magnetotail plasmas
Authors: Ji Xiao‐Fei , Wang Xiao‐Gang , Sun Wei‐Jie , Xiao Chi‐Jie , Shi Quan‐Qi , Liu Jiang , Pu Zu‐Yin 
Published: May 2014

AbstractA new approach of electron magnetohydrodynamics (EMHD) is developed by including the anisotropy of the electron pressure tensor to take Biermann battery effect into account. Based on the model, the dispersion relation of slow and fast electron magnetosonic modes are derived. A Korteweg‐de Vries equation is then obtained from the wave equation to get a solution of one‐dimensional slow‐mode soliton. Furthermore, according to measurements of Cluster and Time History of Events and Macroscale Interactions during Substorms, we find a good agreement between the theory and observations of magnetic field depression and perpendicular pressure increase.
Thermo‐poro‐mechanics of chemically active creeping faults: 3. The role of serpentinite in episodic tremor and slip sequences, and transition to chaos
Authors: Poulet T. , Veveakis E. , Regenauer‐Lieb K. , Yuen D. A. 
Published: May 2014

AbstractDuring the last decade, knowledge over episodic tremor and slip (ETS) events has increased dramatically owing to the widespread installation of GPS and seismic networks. The most puzzling observations are (i) the periodic nature of slow seismic events, (ii) their localization at intermediate depths (estimated 15–40 km), and (iii) the origin of the nonvolcanic fluids that are responsible for the tremor activity. We reconcile these observations using a first principles approach relying on physics, continuum mechanics, and chemistry of serpentinite in the megathrust interface. The approach reproduces the GPS sequences of 17 years of recording in Cascadia, North America, as well as over 10 years in the Hikurangi Trench of New Zealand. We show that strongly endothermic reactions, such as serpentinite dehydration, are required for ETS events. We report that in this tectonic setting, it is its chemical reaction kinetics, not the low friction, that marks serpentinite as a key mineral for stable, self‐sustained oscillations. We find that the subduction zone instabilities are driven from the ductile realm rather than the brittle cover. Even when earthquakes in the cover perturb the oscillator, it relaxes to its fundamental mode. Such a transition from stable oscillations to chaos is witnessed in the ETS signal of NZ following the M6.8, 2007 seismic event, which triggered a secondary mode of oscillations lasting for a few years. We consequently suggest that the rich dynamics of ductile modes of failure may be used to decipher the chaotic time sequences underpinning seismic events.
Directed Ruthenium‐Catalyzed C(sp3)H α‐Alkylation of Cyclic Amines Using Dioxolane‐Protected Alkenones
Authors: Kulago Artem A. , Van Steijvoort Ben F. , Mitchell Emily A. , Meerpoel Lieven , Maes Bert U. W. 
Published: May 2014

AbstractA catalytic system for ruthenium‐catalyzed C(sp3)H α‐alkylation of piperidines with dioxolane‐protected alkenones is reported. Dioxolane protection of the ketone proved crucial to obtain alkylation products. A diverse set of highly substituted piperidines was readily prepared in moderate to good yields via this methodology from easily accessible starting materials (C‐2, C‐3 and C‐4 substituted piperidines). When the methodology is applied to C‐3 substituted piperidines, featuring two α positions, only monoalkylated products (2,5‐disubstituted) are observed. Even bicyclic amines, which feature a fused piperidine moiety, can be used. The successful directing group as well as protecting group (ketal) removal is also demonstrated. The methodology thus allows one to further derivatize and access hitherto unknown functionalized cyclic amine derivatives and will be useful in molecular library synthesis.magnified image
Regioselective Synthesis of Indoles via Rhodium‐Catalyzed CH Activation Directed by an In‐Situ Generated Redox‐Neutral Group
Authors: Muralirajan Krishnamoorthy , Cheng Chien‐Hong 
Published: May 2014

AbstractA regioselective synthesis of indoles from arylhydrazine hydrochlorides with alkynes and diethyl ketone catalyzed by a rhodium complex is described. A possible mechanism involving an in‐situ generated oxidizing directing group NNCR1R2 assisted ortho‐CH activation and reductive elimination are proposed. The catalytic reaction is highly compatible with a wide range of functional arylhydrazines and alkynes. The reaction proceeds under mild reaction conditions and is atom‐step economical.magnified image
Synthese, Struktur und Anwendungen von Pyridiniumphosphanen
Authors: Tinnermann Hendrik , Wille Christian , Alcarazo Manuel 
Published: May 2014

AbstractNeue kationische Liganden, die N‐Alkyl/Aryl‐Pyridiniumphosphane, wurden über eine kurze und skalierbare Syntheseroute hergestellt. Die Auswertung der elektronischen Eigenschaften dieser Phosphane zeigte schwaches σ‐Donor‐ und starkes π‐Akzeptorverhalten. Als Hilfsliganden eingesetzt, steigern diese Phosphane die π‐Azidität der entsprechenden PtII‐ und AuI‐Komplexe. Durch die erhöhte π‐Azidität sind die Metallkomplexe dieser Liganden in der Lage, die Aktivität von Alkinen gegenüber nukleophilen Angriffen wesentlich zu erhöhen. Die durch das Ligandendesign erhöhte Reaktivität wird anhand einiger mechanistisch verschiedener Platin(II)‐ und Gold(I)‐katalysierter Reaktionen aufgezeigt.
Synthesis, Structure, and Applications of Pyridiniophosphines
Authors: Tinnermann Hendrik , Wille Christian , Alcarazo Manuel 
Published: May 2014

AbstractA new family of cationic ligands, N‐alkyl/aryl pyridiniophosphines, has been synthesized through a short, scalable, and highly modular route. Evaluation of their electronic properties evidenced weak σ‐donor and quite strong π‐acceptor character when used as ancillary ligands. These attributes confer a substantially enhanced π‐acidity to the PtII and AuI complexes thereof derived and, as result, they depict an improved ability to activate alkynes towards nucleophilic attack. This superior performance has been demonstrated along several mechanistically diverse PtII‐ and AuI‐catalyzed transformations.
Economic pre‐feasibility study for physical conversion of polyethylene terephthalate wastes to activated carbon
Authors: Torrik Ebrahim , Nejati Ehsan , Soleimani Mansooreh 
Published: May 2014

ABSTRACTBeneficial use of waste polymers is an important issue for environmental protection researchers. In this study, a brief summary has been presented for recycling methods of polyethylene terephthalate (PET) wastes. An economic pre‐feasibility study has been performed for the production of activated carbon from PET wastes. The proposed plant was used the physical activation process for the production of 10 000 t of activated carbon per year. The mass and energy balances and equipment designs of the process were performed using Aspen Plus 7.2 software. Asian countries have been selected as the location of this plant. The economic analysis of this plant for 2013 indicated that total capital investment and total production cost of plant were about $13 004 232 and $12 819 125, respectively. Using the economic criteria, the feasibility study of the project was conducted, and it was revealed that for a sale price of $1.7 per kg, minimum values of net present value ($418 486) and internal rate of return (15.33%) and the maximum value for payout period (25.44 years) have been reached. As it was expected, both net present value and internal rate of return increase by increasing sale price, while payout period decreases. This sensitivity analysis indicated that interest rate is the most effective parameter on net present value in each of the sale prices. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Aging behavior and mechanism of bio‐based engineering polyester elastomer nanocomposites
Authors: Fang Bowen , Kang Hailan , Wang Runguo , Wang Zhao , Wang Wencai , Zhang Liqun 
Published: May 2014

ABSTRACTBio‐based elastomers used in industry have attracted much attention. We prepared bio‐based engineering polyester elastomer (BEE) nanocomposites by mixing bio‐based engineering polyester elastomers with carbon (CB). The CB/BEE nanocomposites were exposed to an artificial weathering environment for different time periods. Both its aging behavior changes and aging mechanism were investigated in this article. The tensile strength retention rates were each above 90% after aging at 100°C and 125°C for 72 h. CB/BEE nanocomposites exhibited good anti‐aging properties. Furthermore, the chemical changes were detected by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crosslink density changes during aging of BEE were determined as well. A plausible aging mechanism of BEE was proposed. It can be concluded that the thermal oxidation process gives priority to further crosslinking in the initial period of aging. As the aging time increases, chain scission becomes the dominant element in the subsequent thermal oxidation process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40862.
Surface selectivity competition of newly synthesized polyarylidene(keto amine) polymers toward different metal ions
Authors: Hussein Mahmoud A. , Marwani Hadi M. , Alamry Khalid A. , Asiri Abdullah M. , El‐Daly Samy A. 
Published: May 2014

ABSTRACTA new series of polyarylidene(keto amine)s (PAKAs) 3a−3e based on thiophene moieties in polymer main chains were synthesized with the solution polycondensation technique. The polymers were synthesized by the reaction of the new monomer 1,1′‐(1E,1′E)‐(2‐oxocyclohexane‐1,3‐diylidene)bis(methanylylidene)bis(thiophene‐5,2‐diyl)bis(2‐chloroethanone) (2) with different diamines. The new monomer was first synthesized under the normal conditions of the Friedel–Crafts reaction. The results obtained from both elemental and spectral analyses were consistent with the chemical structure of the new monomers and the polymers. Moreover, the identification of the polymers was carried out with different characterization techniques. The analytical competition of the newly synthesized PAKA polymers as selected examples (3d and 3e) was also evaluated for a selective extraction of metal ions, including Cd(II), Co(II), Cu(II), Cr(III), Fe(III), Ni(II), and Zn(II), before their determination by inductively coupled plasma–optical emission spectrometry. The results of the selectivity study demonstrated that the 3d and 3e polymers was the most selective toward Co(II) and Fe(III), respectively. However, the adsorption capacity of 3d for Co(II) was improved by 10.10% in comparison to that of 3e for Fe(III) after only 1 h of contact time. Moreover, the adsorption isotherm data also showed that the adsorption process was mainly monolayer on the homogeneous adsorbent surfaces of both polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40873.
Developing toughened aromatic polybenzoxazines using thermoplastic oligomers and telechelics, part 1: Preparation and characterization of the functionalized oligomers
Authors: Hamerton Ian , McNamara Lisa T. , Howlin Brendan J. , Smith Paul A. , Cross Paul , Ward Steven 
Published: May 2014

ABSTRACTThe preparation and characterization of three families of thermoplastic oligomers (Mn = 2918–13263 g mol−1) based on polyarylsulfone (PSU) differing in both molecular weight and terminal functionality and one series of polyarylethersulfone (PES) of different molecular weights is reported. Infrared and nuclear magnetic resonance spectroscopy data support the formation of both the hydroxyl terminated oligomers and conversion (67–89% depending on molecular weight) to the telechelic PSU oligomer bearing reactive benzoxazine groups. Differential scanning calorimetry reveals that the onset of homopolymerization in the telechelic PSU oligomer occurs at around 100°C (peak maximum 125°C at 10 K/min) and rescans show values of the glass transition (for the homopolymers) ranging from 124 to 167°C depending on molecular weight. The influence on the oligomer backbone and terminal functionality is examined using thermal analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40875.
Enhancing rheological properties of hydrophobically associative polyacrylamide aqueous solutions by hybriding with silica nanoparticles
Authors: Zhu Dingwei , Han Yugui , Zhang Jichao , Li Xiaolan , Feng Yujun 
Published: May 2014

ABSTRACTOrganic/inorganic hybrid aqueous solutions were prepared by mixing silica nanoparticle suspension and hydrophobically associating polyacrylamide (HAPAM) solution, and their rheological behaviors were examined in both pure water and brine in comparison with HAPAM. It was found that HAPAM/silica hybrid exhibits viscosity enhancement in aqueous solution and better heat‐ and salt‐ tolerances than HAPAM. Meanwhile, their long‐term thermal stability is also improved. Cryo‐TEM observation reveals that a reinforced three‐dimensional network structure of HAPAM/silica hybrid is formed. These improved properties are attributed to the formed hydrogen bond between carbonyl groups in HAPAM skeleton and silanol functionalities in silica nanoparticles in the hybrid system, and the silica nanoparticles in the hybrid act as physical crosslinkers between macromolecules. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40876.
Morphological and local mechanical surface characterization of ballistic fibers via AFM
Authors: Strawhecker Kenneth E. , Cole Daniel P. 
Published: May 2014

ABSTRACTAs‐received morphologies, defect structures, and contact moduli of Kevlar KM2 Plus and three other ballistic fibers varying in chemistry and processing, were observed and compared using atomic force microscopy (AFM) and instrumented nanoindentation (NI) techniques. Surface features and defects were defined and measured for each fiber chemistry: p‐phenylene terephthalamides (PPTA including KM2 Plus and Twaron), co‐polymer aramid (AuTx), and ultra high molecular weight polyethylene (UHMWPE including Dyneema). Although a multitude of surface defects were observed in each fiber, the types of defects were similar from one fiber type to another. It was found that surface defects generally map to a more compliant local modulus value. Contact modulus values were compared with NI elastic modulus values to demonstrate validity for the AFM technique. Challenges and limitations of the AFM technique for cataloging defects are discussed. This study is the first which attempts to outline the various morphologies found on several fiber surfaces. These local property studies will enable future comparisons with single filament and bulk fiber properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40880.
Adhesion between polymer surface modified by graft polymerization and tissue during surgery using an ultrasonically activated scalpel device
Authors: Nam Kwangwoo , Iwata Takuya , Kimura Tsuyoshi , Ikake Hiroki , Shimizu Shigeru , Masuzawa Toru , Kishida Akio 
Published: May 2014

ABSTRACTIn the field of surgery, achieving adhesion between a polymer implant and tissue poses a challenge considering that suturing is not appropriate for the stability of such implants. An ultrasonically activated scalpel that generates heat by mechanical vibration and promotes adhesion between a polymer implant and native tissue by pressing the two materials together has very good potential for application in the field. To determine the type of polymer that is suitable for the purpose, we investigated polyethylene (PE) and polystyrene (PS) films, the surfaces of which were activated by corona discharge. Graft polymerization was then performed on the corona‐treated surfaces to vary their properties. The corona‐treated PE and PS films grafted with poly(acrylic acid), poly(methacrylic acid), poly(vinyl benzylacrylic acid), and poly(hydroxylethyl acrylate), respectively, adhered to the tissue when the ultrasonically activated scalpel was applied. The heat generated by the mechanical vibration and the applied pressure enabled the carboxyl or hydroxyl groups to bond with the proteins in the extracellular matrix. We therefore concluded that it was possible to integrate this technique in the development of new types of polymer devices that could be stably implanted in a living body. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40885.
Target‐Triggered NIR Emission with a Large Stokes Shift for the Detection and Imaging of Cysteine in Living Cells
Authors: Zhao Chunchang , Li Xiuai , Wang Feiyi 
Published: May 2014

AbstractBackground autofluorescence from biological systems generally reduces the sensitivity of a fluorescent probe for imaging biological targets. Addressing this challenge requires the development of fluorescent probes that produce emission in the near‐infrared region. Herein, we report the design and synthesis of a fluorescent probe that generates an NIR emission with a large Stokes shift upon the selective response to Cys over Hcy and GSH. The probe is designed to consist of two Cys‐sensing sites, an acrylate ester and an aldehyde installed ortho to each other. The reaction of the probe with Cys triggers an excited state intramolecular proton transfer process upon photo‐excitation, thereby producing an NIR emission with a large Stokes shift. Accordingly, this probe hold great promise for the selective detection of Cys in biological systems. We further demonstrate the capacity of this probe for Cys imaging in living cells.
On‐line Parameter Estimation via Algebraic Method: An Experimental Illustration
Authors: Delpoux R. , Floquet T. 
Published: May 2014

AbstractThis article presents an algebraic online parameters estimation method for linear time invariant (LTI) systems, subject to polynomial perturbations. Particular attention is given to practical implementation. The estimator may be expressed as a simple finite impluse response (FIR) filter, which is advantageous for online application, since the coefficients may be computed offline. The robustification against possible singularities is shown, the approach has the advantage to eliminate singularities that may occur in the experimental identification. This algorithm is illustrated experimentally on a permanent magnet stepper motor (PMSM) and a magnetic bearing for which parametric estimation is known to be a difficult task. The parameters to be estimated are sometimes measurable with difficulty and may vary slightly over time.