bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early morning irregularities detected with spaceborne GPS measurements in the topside ionosphere: A multisatellite case study
Authors: Zakharenkova Irina , Astafyeva Elvira , Cherniak Iurii 
Published: September 2015

AbstractWe present observations of the equatorial plasma bubbles (EPB) in the topside ionosphere at early morning hours (05–08 LT) in the recovery phase of the 18–19 February 2014 geomagnetic storm. This rare type of irregularities was detected in the Pacific sector using GPS measurements on board several low‐Earth‐orbit (LEO) satellites. We use a multisatellite constellation consisted of the three Swarm and one TerraSAR‐X satellites, that on 19 February flew in the same region and at similar altitudes ~500 km. The EPB occurrence in the LEO GPS data was observed for several consecutive orbits from ~11 UT to 16–17 UT on 19 February 2014, which suggests the following: (1) rather long duration (hours) of favorable conditions for EPB generation, (2) formation and evolution of EPB over wide longitude range of the Pacific Ocean, and (3) possible movement of the EPB region in the westward direction (with dawn). Registration of the early morning EPB in LEO GPS data was supported by concurrent in situ (Swarm and DMSP (Defense Meteorological Satellite Program)) and ground‐based (ionosonde and GPS) measurements. LEO‐based GPS technique is found to be essential and promising data source to study the topside EPB over regions with lack of the ground‐based facilities. In addition, we use the Prompt Penetration Model and the Thermosphere‐Ionosphere Electrodynamics Global Circulation Model (TIE‐GCM) to identify the possible mechanisms responsible for the observed phenomenon. The model simulation results indicate the occurrence of the zone with the enhanced vertical plasma drift (~40–45 m/s) owing to the disturbance dynamo action in the predawn/dawn sector during 09–17 UT.
A Route to 1‐Alkenylphosphine Derivatives via the Zr‐Catalyzed Reaction of 1‐Alkynylphosphines with Triethylaluminum
Authors: Ramazanov Ilfir R. , Kadikova Rita N. , Saitova Zukhra R. , Dzhemilev Usein M. 
Published: September 2015

AbstractThe Cp2ZrCl2‐catalyzed reaction of 1‐alkynyldiphenylphosphines with Et3Al, followed by deuterolysis and oxidation, affords substituted (E)‐(but‐1‐en‐1‐yl‐1,4‐d2)diphenylphosphine oxides. It is suggested that the reaction proceeds through the formation of intermediate aluminacyclopent‐2‐enes. Substituted (E)‐but‐1‐en‐1‐yldiphenylphosphine sulfides and 4‐butyl‐5‐(diphenylphosphoryl)‐1‐phenyl‐2,3‐dihydrophosphole 1‐oxide were prepared by reacting intermediate organoaluminum compounds with S8 and PhPCl2. The mechanism of the cycloalumination of 1‐alkynylphosphines is proposed.
Convergent Synthesis of Solamargine and Analogues Thereof: Structural Revision of 16‐epi‐Solamargine and Cytotoxic Evaluation
Authors: Chen Pengwei , Wang Peng , Liu Li , Qiu Peiju , Zhang Lijuan , Song Ni , Ren Sumei , Guan Huashi , Li Ming 
Published: September 2015

AbstractAn effective and stereoselective protocol for convergent synthesis of solamargine, a representative of spirosolane‐type glycoalkaloids, is reported. HB(C6F5)4‐catalyzed coupling of 26‐azido‐pseudodiosgenin with chacotriosyl trichloroacetimidate as the key step for synthesis of solamargine proceeded in high yield and with excellent stereoselectivity. Three analogues of solamargine were synthesized by the method. Protonation of the nitrogen atom by deuterium chloride had a significant influence on the 1H NMR spectrum of solamargine. On the basis of these results, the structure of 16‐epi‐solamargine was revised to solamargine hydrochloride. The cytotoxicity of solamargine together with its analogues against cancer cell lines was evaluated.
Clear anterior rhinorrhea in the population
Authors: Rodriguez Kenneth , Rubinstein Elaine , Ferguson Berrylin J. 
Published: September 2015

BackgroundClear anterior rhinorrhea is commonly observed in older adults and is widely known as “senile rhinorrhea.” Although appreciated in the literature, no studies support that clear rhinorrhea increases with age. Our goal was to determine the prevalence of clear rhinorrhea in adults and the variation between young and old. Additionally, we sought to determine if clear rhinorrhea was bothersome enough for patients to seek treatment.MethodsA questionnaire was randomly distributed to 158 adults, 76 young adults on the University of Pittsburgh Undergraduate campus, and 82 older adults at Longwood Retirement Community in 2011.ResultsOlder subjects reported more drip and an increase in rhinorrhea over time regardless of gender (p < 0.05). Participants wanting to seek treatment reported drip occurred more often, that they used more tissues, and were more bothered by drip compared to those not wanting treatment (p < 0.05).ConclusionClear, anterior rhinorrhea affects older adults regardless of gender significantly more often and more severely than young adults (p < 0.05). The more frequent and bothersome the nasal drip, the more likely individuals would elect treatment.
On‐Tip Photo‐Modulated Molecular Printing
Authors: Xie Zhuang , Zhou Yu , Hedrick James L. , Chen Peng‐Cheng , He Shu , Shahjamali Mohammad M. , Wang Shunzhi , Zheng Zijian , Mirkin Chad A. 
Published: September 2015

AbstractThe concept of using cantilever‐free scanning probe arrays as structures that can modulate nanoscale ink flow and composition with light is introduced and evaluated. By utilizing polymer pen arrays with an opaque gold layer surrounding the base of the transparent polymer pyramids, we show that inks with photopolymerizable or isomerizable constituents can be used in conjunction with light channelled through the pyramids to control ink viscosity or composition in a dynamic manner. This on‐tip photo‐modulated molecular printing provides novel chemically and mechanically controlled approaches to regulating ink transport and composition in real time and could be useful not only for rapidly adjusting feature size but also for studying processes including photoreactions and mass transport at the nanoscale, self‐assembly, and cell–material interactions.
Polyethylene with Reverse Co‐monomer Incorporation: From an Industrial Serendipitous Discovery to Fundamental Understanding
Authors: Cicmil Dimitrije , Meeuwissen Jurjen , Vantomme Aurélien , Wang Jian , van Ravenhorst Ilse K. , van der Bij Hendrik E. , Muñoz‐Murillo Ara , Weckhuysen Bert M. 
Published: September 2015

AbstractA triethylaluminium(TEAl)‐modified Phillips ethylene polymerisation Cr/Ti/SiO2 catalyst has been developed with two distinct active regions positioned respectively in the inner core and outer shell of the catalyst particle. DRIFTS, EPR, UV‐Vis‐NIR DRS, STXM, SEM‐EDX and GPC‐IR studies revealed that the catalyst produces simultaneously two different polymers, i.e., low molecular weight linear‐chain polyethylene in the Ti‐abundant catalyst particle shell and high molecular weight short‐chain branched polyethylene in the Ti‐scarce catalyst particle core. Co‐monomers for the short‐chain branched polymer were generated in situ within the TEAl‐impregnated confined space of the Ti‐scarce catalyst particle core in close proximity to the active sites that produced the high molecular weight polymer. These results demonstrate that the catalyst particle architecture directly affects polymer composition, offering the perspective of making high‐performance polyethylene from a single reactor system using this modified Phillips catalyst.
Regulating Molecular Recognition with C‐Shaped Strips Attained by Chirality‐Assisted Synthesis
Authors: Liu Xiaoxi , Weinert Zackariah J. , Sharafi Mona , Liao Chenyi , Li Jianing , Schneebeli Severin T. 
Published: September 2015

AbstractChirality‐assisted synthesis (CAS) is a general approach to control the shapes of large molecular strips. CAS is based on enantiomerically pure building blocks that are designed to strictly couple in a single geometric orientation. Fully shape‐persistent structures can thus be created, even in the form of linear chains. With CAS, selective recognition between large host and guest molecules can reliably be designed de novo. To demonstrate this concept, three C‐shaped strips that can embrace a pillar[5]arene macrocycle were synthesized. The pillar[5]arene bound to the strips was a better host for electron‐deficient guests than the free macrocycle. Experimental and computational evidence is provided for these unique cooperative interactions to illustrate how CAS could open the door towards the precise positioning of functional groups for regulated supramolecular recognition and catalysis.
Hollow Carbon Nanofibers Filled with MnO2 Nanosheets as Efficient Sulfur Hosts for Lithium–Sulfur Batteries
Authors: Li Zhen , Zhang Jintao , Lou Xiong Wen (David) 
Published: September 2015

AbstractLithium–sulfur batteries have been investigated as promising electrochemical‐energy storage systems owing to their high theoretical energy density. Sulfur‐based cathodes must not only be highly conductive to enhance the utilization of sulfur, but also effectively confine polysulfides to mitigate their dissolution. A new physical and chemical entrapment strategy is based on a highly efficient sulfur host, namely hollow carbon nanofibers (HCFs) filled with MnO2 nanosheets. Benefiting from both the HCFs and birnessite‐type MnO2 nanosheets, the MnO2@HCF hybrid host not only facilitates electron and ion transfer during the redox reactions, but also efficiently prevents polysulfide dissolution. With a high sulfur content of 71 wt % in the composite and an areal sulfur mass loading of 3.5 mg cm−2 in the electrode, the MnO2@HCF/S electrode delivered a specific capacity of 1161 mAh g−1 (4.1 mAh cm−2) at 0.05 C and maintained a stable cycling performance at 0.5 C over 300 cycles.
Stereodivergent Synthesis of N‐Heterocycles by Catalyst‐Controlled, Activity‐Directed Tandem Annulation of Diazo Compounds with Amino Alkynes
Authors: Liu Kai , Zhu Chenghao , Min Junxiang , Peng Shiyong , Xu Guangyang , Sun Jiangtao 
Published: September 2015

AbstractA stereodivergent synthesis of five‐membered N‐heterocycles, such as 2,3‐dihydropyrroles, and 2‐methylene and 3‐methylene pyrrolidines, has been developed through a tandem annulation of amino alkynes with diazo compounds and involves the trapping of in situ formed intermediates. Mechanistic investigations indicate that the copper‐catalyzed tandem annulations proceed by allenoate formation and subsequent intramolecular hydroamination. In contrast, the rhodium‐catalyzed protocol features a carbenoid insertion into the NH bond and subsequent Conia‐ene cyclization.
Utilizing Reversible Interactions in Polymeric Nanoparticles To Generate Hollow Metal–Organic Nanoparticles
Authors: Li Longyu , Yuan Conghui , Zhou Dongming , Ribbe Alexander E. , Kittilstved Kevin R. , Thayumanavan S. 
Published: September 2015

AbstractThe use of reversible linkers in polymers has been of interest mainly for biomedical applications. Herein, we present a novel strategy to utilize reversible interactions in polymeric nanoparticles to generate hollow metal–organic nanoparticles (MOPs). These hollow MOPs are synthesized from self‐assembled polymeric nanoparticles using a simple metal–comonomer exchange process in a single step. The control over the size of the polymer precursor particles translates into a straightforward opportunity for controlling MOP sizes. The shell thickness of the MOPs could be easily tuned by the concentration of metal ions in solution. The underlying mechanism for the formation of these hollow MOPs has been proposed. Evidence for the generality of the method is provided by its application to a variety of metal ions with different coordination geometries.
Methane as a Selectivity Booster in the Arc‐Discharge Synthesis of Endohedral Fullerenes: Selective Synthesis of the Single‐Molecule Magnet Dy2TiC@C80 and Its Congener Dy2TiC2@C80
Authors: Junghans Katrin , Schlesier Christin , Kostanyan Aram , Samoylova Nataliya A. , Deng Qingming , Rosenkranz Marco , Schiemenz Sandra , Westerström Rasmus , Greber Thomas , Büchner Bernd , Popov Alexey A. 
Published: September 2015

AbstractThe use of methane as a reactive gas dramatically increases the selectivity of the arc‐discharge synthesis of M‐Ti‐carbide clusterfullerenes (M=Y, Nd, Gd, Dy, Er, Lu). Optimization of the process parameters allows the synthesis of Dy2TiC@C80‐I and its facile isolation in a single chromatographic step. A new type of cluster with an endohedral acetylide unit, M2TiC2@C80, is discovered along with the second isomer of M2TiC@C80. Dy2TiC@C80‐(I,II) and Dy2TiC2@C80‐I are shown to be single‐molecule magnets (SMM), but the presence of the second carbon atom in the cluster Dy2TiC2@C80 leads to substantially poorer SMM properties.
Attraction or Repulsion? London Dispersion Forces Control Azobenzene Switches
Authors: Schweighauser Luca , Strauss Marcel A. , Bellotto Silvia , Wegner Hermann A. 
Published: September 2015

AbstractLarge substituents are commonly seen as entirely repulsive through steric hindrance. Such groups have additional attractive effects arising from weak London dispersion forces between the neutral atoms. Steric interactions are recognized to have a strong influence on isomerization processes, such as in azobenzene‐based molecular switches. Textbooks indicate that steric hindrance destabilizes the Z isomers. Herein, we demonstrate that increasing the bulkiness of electronically equal substituents in the meta‐position decreases the thermal reaction rates from the Z to the E isomers. DFT computations revealed that attractive dispersion forces essentially lower the energy of the Z isomers.
SuFEx on the Surface: A Flexible Platform for Postpolymerization Modification of Polymer Brushes
Authors: Yatvin Jeremy , Brooks Karson , Locklin Jason 
Published: September 2015

AbstractPolymer brushes present a unique architecture for tailoring surface functionalities due to their distinctive physicochemical properties. However, the polymerization chemistries used to grow brushes place limitations on the monomers that can be grown directly from the surface. Several forms of click chemistry have previously been used to modify polymer brushes by postpolymerization modification with high efficiency, however, it is usually difficult to include the unprotected moieties in the original monomer. We present the use of a new form of click chemistry known as SuFEx (sulfur(VI) fluoride exchange), which allows a silyl ether to be rapidly and quantitatively clicked to a polymer brush grown by free‐radical polymerization containing native ‐SO2F groups with rapid pseudo‐first‐order rates as high as 0.04 s−1. Furthermore, we demonstrate the use of SuFEx to facilely add a variety of other chemical functional groups to brush substrates that have highly useful and orthogonal reactivity, including alkynes, thiols, and dienes.
Fly ash supported Ni―Fe solid acid catalyst for efficient production of diesel additive: intensification through far‐infrared radiation
Authors: Pradhan Piasy , Chakraborty Rajat 
Published: September 2015

AbstractNovel Ni―Fe solid acid catalyst was prepared through co‐wet impregnation of Fe2 (SO4)3·H2O and Ni (NO3)2·6H2O on fly ash (FA) support. XRD, BET‐BJH, SEM‐EDX, XPS and FTIR methods were employed to characterize the catalyst. The excellent catalyst activity was assessed and optimized in the production of methyl oleate (biodiesel/diesel‐additive). The response surface methodology (RSM) computed optimal parametric values pertaining to maximum oleic acid (OA) conversion (98.37 ± 0.01%) were 15:1 methanol/OA molar ratio, 1:15:2 nickel nitrate: ferric sulphate:FA (wt. ratio) and 4 wt.% (of OA) catalyst concentration in 1 h under conventional heating at mild reaction temperature (60 °C). The optimal catalyst possessed 27.64 m2/g specific surface area and 0.0233 cc/g pore volume with predominantly mesoporous framework. XPS bands confirmed the presence of Fe3+ and mixed Ni2+/Ni3+species rendering an acidity of 5.5 mmol KOH/g. The catalyst comprised of crystalline Fe2O3, Ni2O3 and NiS phases as revealed from XRD analysis. This study also reports the remarkable intensification of esterification reaction through an energy‐efficient application of far‐infrared radiation protocol (1/3rd of conventional power requirement) resulting 99.20% OA conversion in only 10 min at the derived optimal conditions. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.
Core–shell particles of poly(methyl methacrylate)‐block‐poly(n‐butyl acrylate) synthesized via reversible addition–fragmentation chain‐transfer emulsion polymerization and the polymer's application in toughening polycarbonate
Authors: Zhu Yue , Gao Xiang , Luo Yingwu 
Published: September 2015

ABSTRACTPoly(methyl methacrylate) (PMMA) block copolymer is interesting because it is compatible with many polymers. A series of poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate) (PMMA‐b‐PnBA) diblock copolymers with various compositions was synthesized via reversible addition–fragmentation chain‐transfer (RAFT) emulsion polymerization with the amphiphilic oligo(methacrylic acid41‐b‐methyl methacrylate8) RAFT agent as both the polymerization mediator and surfactant. The molecular weights of the block copolymers agreed well with the theoretical prediction, although the polydispersity indices were relatively broad. The resulting core [poly(n‐butyl acrylate)]–shell (PMMA) particles of PMMA‐b‐PnBA were found to be very effective impact modifiers for polycarbonate (PC). The diblock copolymer was well dispersed in 100–300‐nm particles in the PC matrix, and the dispersed particle size was highly dependent on the block copolymer compositions. PMMA250‐b‐PnBA550 (the subscripted number signifies the designed degree of polymerization), which was dispersed into 100‐nm particles, presented the best capability for improving the impacting properties. Compared with the neat PC, the notched impact strength of PC toughened by 5 wt % PMMA250‐b‐PnBA550 was increased by four times to 62.81 kJ/m2 with the same yield strength, a slightly decreased modulus, an increased elongation at break, and an increased tensile strength. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42833.
Light‐scattering capacity of ethylene–vinyl acetate copolymers in polypropylene: Toward high haze and transmittance
Authors: Luo Shanshan , Yi Ping , Xiong Ying , Shen Jiabin , Guo Shaoyun 
Published: September 2015

ABSTRACTLight‐scattering materials were fabricated by the melt blending of polypropylene with an ethylene–vinyl acetate copolymer (EVA) to prevent the glare effect of light‐emitting diodes. The results show that the light‐scattering capacity was remarkably dependent on the phase morphologies of EVA. (1) When EVA was dispersed as spherical droplets, the transmittance and haze gradually increased with the enrichment of EVA, and the half‐peak width of the light‐scattering pattern reached a maximum when 30 wt % EVA was loaded. On the basis of the analysis of Mie scattering theory, the enlargement of scattering particles promoted light transmittance, and more incoming light was deflected at the arclike interfaces. This induced a distinct antiglare effect. (2) When scattering particles deformed and expanded vertically in the light‐transmitting direction, the light‐scattering capacity turned out to be weakened by further enrichment of the EVA phase. The planelike interfaces reduced the deflection of incoming light, and this led to decreases in the scattering angles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42844.
Determination of the fracture energy in polymeric films by in situ photoelasticimetry on double edge notch specimen
Authors: Dubelley Florence , Planes Emilie , Bas Corine , Yrieix Bernard , Flandin Lionel 
Published: September 2015

ABSTRACTThe fracture toughness is key parameters to select polymeric films. The essential work of fracture (EWF) is a phenomenological but efficient way to characterize this resistance to fracture. One can gain valuable information on the resistance to perforation and propagation of flaws. A new technique was developed to better understanding the EWF experiments. A tensile test combined to photoelasticimetry allows following in situ the geometry and amount of plastic deformation on double edge notched specimen. The EWF parameters are determined when the plastic deformation appears constant, so when the fracture energy Wf only contributes to rupture filament. This new methodology requires just a single sample, whereas at least five specimens are required for general method. It will help characterize expensive polymeric films or reveal the heterogeneous behavior, for instance after polymer ageing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42854.
Efficient removal of Cu(II) using amino‐functionalized superparamagnetic nanoparticles prepared via SI‐ATRP
Authors: Yuan Caideng , Cui Mingtong , Feng Longlong , Wang Jingpeng , Peng Yan 
Published: September 2015

ABSTRACTAn amino‐functionalized nano‐adsorbent (DETA‐MNPs) was prepared by a process involving: (1) synthesis of superparamagnetic Fe3O4 nanoparticles; (2) introduction of amino groups after which ATRP initiator was anchored; (3) grafting of glycidyl methacrylate (GMA) via SI‐ATRP; and (4) ring‐opening reaction of epoxy groups with diethylenetriamine (DETA). The nano‐adsorbent was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) and applied to remove Cu(II) in batch experiments. The effects of pH, Cu(II) concentrations, solution ionic strength, and contact time were investigated. The results show that the DETA‐MNPs are spherical with cubic spine structure, high saturation magnetization (41.9 emu g−1), and an average diameter of 10 nm. The maximum Cu(II) adsorption capacity achieves 83.33 mg g−1 at pH 5.0 by Langmuir model. The adsorption process is highly pH‐dependent and reaches equilibrium within 20 min. Furthermore, the DETA‐MNPs exhibit excellent dispersibility and reusability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42859.
Effect of composition on morphology structure and cell affinity of poly(caprolactone‐co‐glycolide)‐co‐poly(ethylene glycol) microspheres
Authors: Li Zhe , Shen Hong , Shuai Kegang , Hu Xixue 
Published: September 2015

ABSTRACTPoly(caprolactone‐co‐glycolide)‐co‐poly(ethylene gylcol) copolymers (PCEG) with various composition were synthesized by copolymerization of GA, CL, and PEG. PCEG microspheres were fabricated by oil‐in‐water (o/w) emulsion and solvent‐evaporation technique. Effect of chemical composition on hydrophilicity, crystallinity, and degradation of the PCEG was investigated. It was demonstrated that morphology structure of the microspheres was greatly influenced by chemical composition and hydrophilicity of the PCEG polymer. PCEG microspheres could change from a smooth structure to a regular porous structure and an irregular structure. Moreover, the pore size of them increased with increment of PEG content and length. Cell attachment and growth on the PCEG microspheres were evaluated by using mouse NIH 3T3 fibroblasts as model cells in vitro. The result showed that the PCEG microspheres with large porous structure were more favorable for cell attachment and growth. Thus the PCEG microspheres with rapid degradation rate and large porous structure possess potential use as injectable scaffolds in tissue engineering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42861.