bluuebunny/crossref_metadata_2025_split huggingface dataset:
Martian ionospheric responses to dynamic pressure enhancements in the solar wind
Authors: Ma Y. J. , Fang X. , Nagy A. F. , Russell C. T. , Toth Gabor 
Published: January 2014

AbstractAs a weakly magnetized planet, Mars ionosphere/atmosphere interacts directly with the shocked solar wind plasma flow. Even though many numerical studies have been successful in reproducing numerous features of the interaction process, these earlier studies focused mainly on interaction under steady solar wind conditions. Recent observations suggest that plasma escape fluxes are significantly enhanced in response to solar wind dynamic pressure pulses. In this study, we focus on the response of the ionosphere to pressure enhancements in the solar wind. Through modeling of two idealized events using a magnetohydrodynamics model, we find that the upper ionosphere of Mars responds almost instantaneously to solar wind pressure enhancements, while the collision dominated lower ionosphere (below ~150 km) does not have noticeable changes in density. We also find that ionospheric perturbations in density, magnetic field, and velocity can last more than an hour after the solar wind returns to the quiet conditions. The topside ionosphere forms complicated transient shapes in response, which may explain unexpected ionospheric behaviors in recent observations. We also find that ionospheric escape fluxes do not correlate directly with simultaneous solar wind dynamic pressure. Rather, their intensities also depend on the earlier solar wind conditions. It takes a few hours for the ionospheric/atmospheric system to reach a new quasi‐equilibrium state.
Transient and local weakening of surface winds observed above the Kuroshio front in the winter East China Sea
Authors: Kasamo Kenki , Isobe Atsuhiko , Minobe Shoshiro , Manda Atsuyoshi , Nakamura Hirohiko , Ogata Koto , Nishikawa Hatsumi , Tachibana Yoshihiro , Kako Shin'ichiro 
Published: January 2014

AbstractTo confirm whether surface winds strengthen above warm waters around oceanic fronts using in situ data, a field measurement was conducted using both expendable bathythermographs and Global Positioning System sondes released concurrently across the Kuroshio front in the East China Sea in December 2010. In contrast to previous studies mainly based on satellite observations, the finding of the present field survey is the local weakening of surface winds at the northern flank of the Kuroshio front. From the above field observation in conjunction with a regional numerical model experiment, it is suggested that the northwesterly winds crossing the Kuroshio front from the cooler side first weaken at the northern flank of the front because of the onset of upward transfer of the “nonslip” condition at the sea surface. Thereafter, as the atmospheric mixed layer with warm and humid air mass develops gradually downwind over the Kuroshio region, the surface winds are gradually accelerated by the momentum mixing with strong winds aloft. The surface winds remain strong over the cool East China Sea shelf, and it is thus considered that the surface winds only weaken at the northern flank of the Kuroshio front. However, numerical modeling indicates that this local weakening of the surface winds occurs as a transient state with a short duration and such a structure has thus rarely been detected in the long‐term averaged wind fields observed by satellites.
Asymmetric Aldol Reaction of 3‐Acetyl‐2H‐chromen‐2‐ones and Isatins Catalyzed by a Bifunctional Quinidine Urea Catalyst
Authors: Abbaraju Santhi , Zhao John Cong‐Gui 
Published: January 2014

AbstractThe asymmetric aldol reaction of 3‐acetyl‐2H‐chromen‐2‐ones and isatins has been realized by using a bifunctional quinidine‐derived urea as the catalyst. The corresponding 3‐hydroxyoxindole derivatives containing a 2H‐chromen‐2‐one moiety were obtained in good yields and high enantioselectivities. When (Z)‐ethyl 2‐benzylideneacetoacetate was used as the substrate, a mixture of two diastereomers (both Z and E) was obtained due to isomerization of the double bond under the reaction conditions.magnified image
Enantioselective Allylation of Thiophene‐2‐carbaldehyde: Formal Total Synthesis of Duloxetine
Authors: Motloch Petr , Valterová Irena , Kotora Martin 
Published: January 2014

AbstractThe enantioselective allylation of thiophene‐2‐carbaldehyde with allyltrichlorosilane under Lewis base catalysis has been studied. The use of catalytic amount (1 mol%) of chiral bipyridine N,N′‐dioxides provided the corresponding 1‐(thiophen‐2‐yl)‐but‐3‐en‐1‐ol with asymmetric induction reaching 97% ee. The prepared chiral (S)‐1‐(thiophen‐2‐yl)‐but‐3‐en‐1‐ol was used as the crucial chiral building block in a formal total synthesis of duloxetine.magnified image
Influence of High‐Energy Ion Irradiation on the Structural, Optical, and Chemical Properties of Polytetrafluoroethylene
Authors: Singh Paramjit , Kumar Rajesh 
Published: January 2014

ABSTRACTPolytetrafluoroethylene (PTFE) polymer samples were irradiated by 50 MeV Li3+ ion beams to the fluences of 1 × 1010, 1 × 1011, and 1 × 1012 ions/cm2. The structural, optical, and chemical properties were studied by X‐ray diffraction (XRD), UV–visible (UV–vis) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, respectively. The XRD analyses showed amorphization of the polymer sample at fluences of 1 × 1010 and 1 × 1011 ions/cm2. Crystallite size (calculated by applying the Scherrer formula) decreased for irradiated samples at fluences of 1 × 1010 and 1 × 1011 ions/cm2. The other factors like microstrain (ε), dislocation density (δ), and distortion parameters (g) showed variations at these fluences. However, there was no change in the interchain separation (R) and interplanar distance (d) for all irradiated samples. UV–vis showed a shift of the absorption edge of irradiated samples towards the visible region. The band gap energy (Eg) was calculated using Tauc's relation, and its value decreased with an increase of ion fluence for all irradiated samples. The number of carbon atoms per conjugation length (N) increased for the irradiated samples. The FTIR results revealed the liberation of CF2 groups and the appearance of some new bands after irradiation.
Technical Note: 3D From Standard Digital Photography of Human Crania—A Preliminary Assessment
Authors: Katz David , Friess Martin 
Published: January 2014

ABSTRACTThis study assessed three‐dimensional (3D) photogrammetry as a tool for capturing and quantifying human skull morphology. While virtual reconstruction with 3D surface scanning technology has become an accepted part of the paleoanthropologist's tool kit, recent advances in 3D photogrammetry make it a potential alternative to dedicated surface scanners. The principal advantages of photogrammetry are more rapid raw data collection, simplicity and portability of setup, and reduced equipment costs. We tested the precision and repeatability of 3D photogrammetry by comparing digital models of human crania reconstructed from conventional, 2D digital photographs to those generated using a 3D surface scanner. Overall, the photogrammetry and scanner meshes showed low degrees of deviation from one another. Surface area estimates derived from photogrammetry models tended to be slightly larger. Landmark configurations generally did not cluster together based upon whether the reconstruction was created with photogrammetry or surface scanning technology. Average deviations of landmark coordinates recorded on photogrammetry models were within the generally allowable range of error in osteometry. Thus, while dependent upon the needs of the particular research project, 3D photogrammetry appears to be a suitable, lower‐cost alternative to 3D imaging and scanning options. Am J Phys Anthropol 154:152–158, 2014. © 2014 Wiley Periodicals, Inc.
The relationship between bending stress and the shape of maxillary canines in cercopithecoid monkeys
Authors: Rapoff Andrew J. , McGraw W. Scott , Daegling David J. 
Published: January 2014

ABSTRACTPrimate canines function in social displays but are also recruited for biting in agonistic encounters. Although the precise nature of the loads such behavior places on the canine crown is unknown, it is thought that bending is a major component of such loads. To date, modeling of canine bending strength has relied on idealized geometric representations. Accounting for the tapering of the crown as well as shape changes along an apical–basal axis provides a more realistic model for assessment of bending stress in canines. We provide such an accounting and evaluate the hypothesis that the morphology of the cercopithecoid canine represents a structural solution for maintaining constant maximum bending stress under apical or distributed loading in a parasagittal plane. This isostress hypothesis is analogous to a design criterion of minimum mass for a given structural requirement. Examining permanent maxillary canines from males and females representing eight West African cercopithecoid species, we reconstructed crown geometry from apex to base using microcomputed tomography. From reconstructed cross‐sections, we determined section moduli about a buccolingual centroidal axis. We then determined what the taper should be for a variety of parasagittal loading distributions if the isostress hypothesis were true and compared these theoretical tapers to actual crown geometry. We found that a variety of loading distributions can be accommodated by the canines, particularly among males. These results suggest that our sample of canines are not optimized for resisting particular biting loads, but effectively limit stress gradients associated with a range of behaviors. Am J Phys Anthropol 154:61–69, 2014. © 2014 Wiley Periodicals, Inc.
Anisotrope Gold‐Nanopartikel: Synthese, Eigenschaften, Anwendungen und Toxizität
Authors: Li Na , Zhao Pengxiang , Astruc Didier 
Published: January 2014

AbstractAnisotrope Gold‐Nanopartikel (AuNPs) ziehen seit einem Jahrhundert das Interesse der Wissenschaftler auf sich. Vor allem in den letzten 10 Jahren hat sich das Gebiet rasant entwickelt, einhergehend mit der Synthese unzähliger ein‐, zwei‐ und dreidimensionaler massiver und hohler AuNP‐Strukturen. Die Anisotropie dieser nichtsphärischen, hohlen und schalenartigen AuNP‐Strukturen bedingt ihre charakteristische Plasmonenabsorption im sichtbaren und nahinfraroten (NIR) Bereich. Speziell die NIR‐Absorption hängt sehr empfindlich von der Nanopartikelform und dem Medium ab und kann in den Bereich des NIR‐Spektrums verschoben werden, in welchem lebendes Gewebe am geringsten absorbiert. Dadurch ergeben sich wichtige Anwendungen in der medizinischen Diagnostik und Therapie (“Theranostik”). Von besonderem Interesse sind hier Nanoschalen und Nanostäbe sowie hohle Nanokugeln und Nanowürfel. Eine andere wichtige Anwendung sind Au‐Nanodrähte (AuNWs), die in Längen von bis zu 100 µm synthetisiert und als Plasmonenwellenleiter für optische Bauelemente genutzt werden können. Insgesamt breiten sich die Anwendungsmöglichkeiten anisotroper AuNPs rasch in den Gebieten der Optik, Biomedizin und Katalyse aus. In diesem Aufsatz geben einen kurzen historischen Überblick über das Thema und fassen dann die Synthesemethoden, Morphologien, Anwendungen und Toxizitätseigenschaften dieser schnell wachsenden Klasse von Nanomaterialien zusammen.
Gemischte Übergangsmetalloxide: Design, Synthese und energierelevante Anwendungen
Authors: Yuan Changzhou , Wu Hao Bin , Xie Yi , Lou Xiong Wen (David) 
Published: January 2014

AbstractSeit kurzem findet eine Familie gemischter Übergangsmetalloxide (mixed transition‐metal oxides, MTMOs; beschrieben durch AxB3−xO4; A, B=Co, Ni, Zn, Mn, Fe usw.) mit stöchiometrischen oder gar nichtstöchiometrischen Zusammensetzungen (typischerweise in Spinellstruktur) weltweit Interesse. Diese MTMOs dürften dank ihrer ausgezeichneten elektrochemischen Eigenschaften große Bedeutung für kostengünstige und umweltfreundliche Technologien zur Energiespeicherung/‐umwandlung erlangen. In diesem Aufsatz fassen wir die jüngsten Fortschritte beim rationalen Design von MTMOs mit steuerbaren Formen, Größen, Zusammensetzungen und Mikro‐/Nanostrukturen sowie ihren Anwendungsmöglichkeiten zusammen, z. B. als Elektrodenmaterialien für Lithium‐Ionen‐Batterien und elektrochemische Kondensatoren oder als effiziente Elektrokatalysatoren bei der Sauerstoffreduktionsreaktion in Sauerstoff/Luft‐Batterien und Brennstoffzellen. Zum Schluss diskutieren wir die weitere mögliche Entwicklung von MTMOs für die nächste Technologiegeneration der elektrochemischen Energiespeicherung/‐umwandlung.
An Efficient RuII–RhIII–RuII Polypyridyl Photocatalyst for Visible‐Light‐Driven Hydrogen Production in Aqueous Solution
Authors: Stoll Thibaut , Gennari Marcello , Fortage Jérôme , Castillo Carmen E. , Rebarz Mateusz , Sliwa Michel , Poizat Olivier , Odobel Fabrice , Deronzier Alain , Collomb Marie‐Noëlle 
Published: January 2014

AbstractThe development of multicomponent molecular systems for the photocatalytic reduction of water to hydrogen has experienced considerable growth since the end of the 1970s. Recently, with the aim of improving the efficiency of the catalysis, single‐component photocatalysts have been developed in which the photosensitizer is chemically coupled to the hydrogen‐evolving catalyst in the same molecule through a bridging ligand. Until now, none of these photocatalysts has operated efficiently in pure aqueous solution: a highly desirable medium for energy‐conversion applications. Herein, we introduce a new ruthenium–rhodium polypyridyl complex as the first efficient homogeneous photocatalyst for H2 production in water with turnover numbers of several hundred. This study also demonstrates unambiguously that the catalytic performance of such systems linked through a nonconjugated bridge is significantly improved as compared to that of a mixture of the separate components.
A Diiron(III,IV) Imido Species Very Active in Nitrene‐Transfer Reactions
Authors: Gouré Eric , Avenier Frédéric , Dubourdeaux Patrick , Sénèque Olivier , Albrieux Florian , Lebrun Colette , Clémancey Martin , Maldivi Pascale , Latour Jean‐Marc 
Published: January 2014

AbstractMetal‐catalyzed nitrene transfer reactions arouse intense interest as clean and efficient procedures for amine synthesis. Efficient Rh‐ and Ru‐based catalysts exist but Fe alternatives are actively pursued. However, reactive iron imido species can be very short‐lived and getting evidence of their occurrence in efficient nitrene‐transfer reactions is an important challenge. We recently reported that a diiron(III,II) complex is a very efficient nitrene‐transfer catalyst to various substrates. We describe herein how, by combining desorption electrospray ionization mass spectrometry, quantitative chemical quench experiments, and DFT calculations, we obtained conclusive evidence for the occurrence of an {FeIIIFeIVNTosyl} intermediate that is very active in H‐abstraction and nitrene‐transfer reactions. DFT calculations revealed a strong radical character of the tosyl nitrogen atom in very low‐lying electronic configurations of the FeIV ion which are likely to confer its high reactivity.
Mechanical and chemical properties of poly(styrene‐isobutylene‐styrene) block copolymers: Effect of sulfonation and counter ion substitution
Authors: Suleiman David , Padovani Agnes M. , Negrón Arnaldo A. , Sloan James M. , Napadensky Eugene , Crawford Dawn M. 
Published: January 2014

ABSTRACTIn this study, the mechanical and chemical properties of a series of sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) block copolymers were evaluated using a combination of nanoindentation, dynamic mechanical analysis (DMA), elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), water absorption, and small angle X‐ray scattering studies (SAXS). The materials properties were characterized as a function of the sulfonation percent in the block copolymers, as well as a result of the counter‐ion substitution with Mg2+, Ca2+, and Ba2+. Nanoindentation studies revealed that the elastic modulus (E) and hardness (H) increase with sulfonation up to a certain level, at which point, the effect of water content further hinders any mechanical reinforcement. The incorporation of counter‐ions increases E and H, but the results are dependent upon the size of the counter‐ion. DMA results showed that the polymer maintained the glass transition temperature (Tg) of the polyisobutylene (PIB) segment (−60°C) regardless of the sulfonation level or counter‐ion substituted. However, both the shoulder of the PIB Tg (−30°C), which was probably caused by a Rouse‐type motion, as well as the Tg of polystyrene (105°C) disappeared upon sulfonation. Counter‐ion substitution increased the storage modulus of the rubbery plateau, which is indicative of a stronger and more thermally stable crosslinked complex formation. Additional unique relaxations were observed with the counter‐ions, and could be attributed to the stretching/rotation of the SO bond and the interaction of the cations with the oxygen in the sulfonic group. FTIR results also revealed a unique shifting of the asymmetric SO band when counter‐ions were added. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40344.
Wireless in‐mold melt front detection for injection molding: A long‐term evaluation
Authors: Müller Florian , Kukla Christian , Lucyshyn Thomas , Harker Matthew , Rath Gerhard , Holzer Clemens 
Published: January 2014

ABSTRACTWireless sensing technology for injection molding is of increasing interest in literature. Recently, a purely mechanical in‐mold sensor for melt front detection was introduced. The sensor system is based on building resonant structures into the mold which are excited by the passing melt front generating structure‐borne sound, from which the melt front position is derived. A big advantage of this system is the possibility to implement a plurality of resonant structures while just having one receiver. One important aspect is the need to separate and assign the recorded impinging sounds. A novel algebraic approach was introduced separating the resonant structures by reference to their oscillatory behavior. In this article, measurement results for over 450 injection molding cycles are given proving functionality of the separation process. In addition, it is shown that the melt front detection is reliable and robust when comparing it with results obtained by cavity temperature sensors. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40346.
Nylon‐coated ultra high molecular weight polyethylene fabric for enhanced penetration resistance
Authors: Firouzi Dariush , Foucher Daniel A. , Bougherara Habiba 
Published: January 2014

ABSTRACTA coating of Nylon 6,6 or 6,12 was used to improve the penetration resistance of ultra high molecular weight polyethylene (UHMWPE) fabric that would be potentially useful in the manufacture of flexible body armor against spike/knife threats. Quasi‐static test results for the spike penetrator showed a 77% and 86% improvement in the puncture resistance of Nylon 6,6 and Nylon 6,12 coated UHMWPE (respectively) over a neat fabric target of equivalent areal densities. Dynamic impact testing demonstrated dramatic improvement in the puncture resistance of nylon‐coated fabrics while only a slight improvement in stab resistance was observed comparing samples with equivalent areal densities. Photography of ruptured areas after quasi‐static testing revealed limited fiber motion or fiber stretching with no evidence of fiber pullout for nylon‐coated fabric samples in contrast to neat fabric. This suggests that there was a significant increase in energy absorption by nylon‐coated fabrics at impact. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40350.
Diester based on castor oil fatty acid as plasticizer for poly(vinyl chloride)
Authors: Mehta Bhakti , Kathalewar Mukesh , Sabnis Anagha 
Published: January 2014

ABSTRACTCastor oil is a renewable resource that has potential uses as an environmental friendly material for a range of applications. In recent years, much efforts have been driven to develop alternate plasticizer for medical and commodity plastics due to growing concerns about dioctyl phthalate (DOP) for flexible poly(vinyl chloride) (PVC). In this study, a bio‐based plasticizer was synthesized by a two‐step esterification reaction of castor oil fatty acid (COFA) with benzyl alcohol and octanoic acid in the presence of catalyst (dibutyl tin dilaurate). The structure of the octanoic ester (OE) was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, acid value, and hydroxyl value. OE was used as a coplasticizer in PVC for partial replacement of DOP. The addition of OE exhibited good incorporation and plasticizing performance in the PVC sheets. Incorporation of OE resulted in good plasticizing, tensile strength, percentage elongation, exudation, thermal stability, and chemical resistance because of the presence of long carbon chains of COFA. Differential scanning calorimetry (DSC), thermogravimetric analysis, and color measurements were also performed to evaluate the effect of OE. With the increase in OE, DSC and hardness results showed marginal deviation from those obtained for DOP‐plasticized sheets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40354.
Evaluation of liquid chromatography–ion trap–time of flight hybrid mass spectrometry on the quantitative analysis for ginsenosides
Authors: Xing Lu. , Xie Lin , Liang Yan , Xing Rong , Rao Tai , Zhou Lijun , Wang Qian , Fu Hanxu , Ye Wei , Wang Guangji 
Published: January 2014

ABSTRACTIt is ideal and desirable for a single instrument to meet the requirement of both qualitative and quantitative analysis of complicated components in pharmacokinetic research for herbal medicine. Liquid chromatography combined with hybrid ion trap and time‐of‐flight mass spectrometry (LCMS‐IT‐TOF) was recently confirmed as a very powerful tool for the qualitative analysis of both target and nontarget components in herbal medicines. The present study was designed to investigate the feasibility of LCMS‐IT‐TOF on quantitative analysis of ginsenosides in biological matrices. A simple liquid–liquid extraction procedure was followed by injection of the extracts onto a C18 column with gradient elution and detection based on LCMS‐IT‐TOF system in negative scan mode. The developed method was validated with respect to the limit of quantification, linear dynamic range, precision, accuracy, matrix effects and stabilities. All the results suggested that the presently developed method was sufficiently sensitive and robust enough to simultaneously monitor 15 ginsenosides with diverse properties and a large range of concentration differences. Therefore, this method would be expected to be highly useful for comprehensive studies of ginsenosides in complicated matrix. Copyright © 2014 John Wiley & Sons, Ltd.