bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing high-mass stellar evolutionary models with binary stars
Authors: Tkachenko A.
Published: January 2015

Mass discrepancy is one of the problems that is pending a solution in (massive) binary star research field. The problem is often solved by introducing an additional near core mixing into evolutionary models, which brings theoretical masses of individual stellar components into an agreement with the dynamical ones. In the present study, we perform a detailed analysis of two massive binary systems, V380 Cyg and σ Sco, to provide an independent, asteroseismic measurement of the overshoot parameter, and to test state-of-the-art stellar evolution models.
Leaky-wave-induced disks around Be stars: a pulsational analysis on their formation
Authors: Godart Melanie , Shibahashi Hiromoto , Dupret Marc-Antoine
Published: January 2015

Be stars are B-type stars near the main sequence which undergo episodic mass loss events detected by emission lines, whose line shape and intensity vary with a timescale of the order of decades. Spectroscopic observations show a large rotation velocity such that one of the prevailing scenarios for the formation of the equatorial disk consists in an increasing equatorial rotation velocity to the break-up limit where gravity is challenged by the centrifugal force. We investigate here a new scenario recently suggested by Ishimatsu & Shibahashi (2013), in which the transport of angular momentum through the photosphere would be achieved by leaky waves, keeping the rotation velocity still below the break-up limit.
Deep Photospheric Emission Lines as Probes for Pulsational Waves
Authors: Rivinius Th. , Shultz M. , Wade G. A.
Published: January 2015

Weak line emission originating in the photosphere is well known from O stars and widely used for luminosity classification. The physical origin of the line emission are NLTE effects, most often optical pumping by far-UV lines. Analogous lines in B stars of lower luminosity are identified in radially pulsating β Cephei stars. Their diagnostic value is shown for radially pulsating stars, as these lines probe a much larger range of the photosphere than absorption lines, and can be traced to regions where the pulsation amplitude is much lower than seen in the absorption lines.
Seismic analysis of the massive β Cephei star 15 Canis Majoris
Authors: Walczak Przemysław , Handler Gerald
Published: January 2015

15 Canis Majoris is a quite massive (M~ 14 M⊙) main sequence pulsator of the β Cephei type. Recent photometric (Handler 2014) and spectroscopic (Saesen & Briquet, priv. comm.) observations confirm four pulsational frequencies and indicate possible additional modes. We calculated models fitting two frequencies identified as radial and dipole modes. Our analysis indicates rather effective overshooting from the convective core as well as a strong dependence of the minimal required overshooting parameter (αov,min) on the metallicity,Z(αov,min~ -2.5 Z).

When incorporating the non-adiabaticf-parameter (Daszynśka-Daszkiewicz & Walczak 2009), defined as the ratio of the bolometric flux changes to the radial displacement, significant differences between the opacity tables were obtained. The comparison of the models derived with different codes is also interesting. We used two evolutionary codes: Warsaw-New Jersey (Pamyatnykhet al.1998) and MESA (Paxtonet al.2011) and some systematic differences were found.
Basics of Optical Interferometry: A Gentle Introduction
Authors: van Belle Gerard T.
Published: January 2015

The basic concepts of long-baseline optical interferometery are presented herein.
Zooming into Eta Carinae with interferometry
Authors: Groh Jose H.
Published: January 2015

Shaped by strong mass loss, rapid rotation, and/or the presence of a close companion, the circumstellar environment around the most massive stars is complex and anything but spherical. Here we provide a brief overview of the high spatial resolution observations of Eta Carinae performed with the Very Large Telescope Interferometer (VLTI). Special emphasis is given to discuss VLTI/AMBER and VLTI/VINCI observations, which directly resolve spatial scales comparable to those where mass loss originates. Studying scales as small as a few milli-arcseconds allows us to investigate kinematical effects of rotation and binarity in more detail than ever before.
On the atmospheric structure and fundamental parameters of red supergiants
Authors: Wittkowski M. , Arroyo-Torres B. , Marcaide J. M. , Abellan F. J. , Chiavassa A. , Freytag B. , Scholz M. , Wood P. R. , Hauschildt P. H.
Published: January 2015

We present near-infrared spectro-interferometric studies of red supergiant (RSG) stars using the VLTI/AMBER instrument, which are compared to previously obtained similar observations of AGB stars. Our observations indicate spatially extended atmospheric molecular layers of water vapor and CO, similar as previously observed for Mira stars. Data of VY~CMa indicate that the molecular layers are asymmetric, possibly clumpy. Thanks to the spectro-interferometric capabilities of the VLTI/AMBER instrument, we can isolate continuum bandpasses, estimate fundamental parameters of our sources, locate them in the HR diagram, and compare their positions to recent evolutionary tracks. For the example of VY CMa, this puts it close to evolutionary tracks of initial mass 25-32 M⊙. Comparisons of our data to hydrostatic model atmospheres, 3d simulations of convection, and 1d dynamic model atmospheres based on self-excited pulsation models indicate that none of these models can presently explain the observed atmospheric extensions for RSGs. The mechanism that levitates the atmospheres of red supergiant is thus a currently unsolved problem.
The impact of the rotation on the surface brightness of early-type stars
Authors: Challouf M. , Nardetto N. , de Souza A. Domiciano , Mourard D. , Aroui H. , Stee P. , Meilland A.
Published: January 2015

The surface brightness colors (SBC) relation is a very important tool to derive the distance of extragalactic eclipsing binaries. However, for early-type stars, this SBC relation is critically affected by the stellar environment (wind, circumstellar disk, etc...) and/or by the fast rotation. We calculated 6 models based on the code of Domiciano de Souza et al. (2012) considering different inclinations and rotational velocities. Using these results, we quantify for the first time the impact of the rotation on the SBC relation.
The circumstellar environment of the B[e] star GG Car: an interferometric modeling
Authors: de Souza A. Domiciano , Fernandes M. Borges , Carciofi A. C. , Chesneau O.
Published: January 2015

The research of stars with the B[e] phenomenon is still in its infancy, with several unanswered questions. Physically realistic models that treat the formation and evolution of their complex circumstellar environments are rare. The code HDUST (developed by A. C. Carciofi and J. Bjorkman) is one of the few existing codes that provides a self-consistent treatment of the radiative transfer in a gaseous and dusty circumstellar environment seen around B[e] supergiant stars. In this work we used the HDUST code to study the circumstellar medium of the binary system GG Car, where the primary component is probably an evolved B[e] supergiant. This system also presents a disk (probably circumbinary), which is responsible for the molecular and dusty signatures seen in GG Car spectra. We obtained VLTI/MIDI data on GG~Car at eight baselines, which allowed to spatially resolve the gaseous and dusty circumstellar environment. From the interferometric visibilities and SED modeling with HDUST, we confirm the presence of a compact ring, where the hot dust lies. We also show that large grains can reproduce the lack of structure in the SED and visibilities across the silicate band. We conclude the dust condensation site is much closer to the star than previously thought. This result provides stringent constraints on future theories of grain formation and growth around hot stars.
Recent highlights of spectropolarimetry applied to the magnetometry of massive stars
Authors: Grunhut J. H.
Published: January 2015

Spectropolarimetry is a powerful tool used to probe fundamental properties of stars that cannot typically be measured in any other way. A new generation of high-resolution spectropolarimeters (ESPaDOnS at the Canada-France-Hawaii telescope, Narval at the Télescope Bernad Lyot, and HARPSpol at the 3.6-m ESO telescope) and dedicated observing campaigns (such as the Magnetism in Massive Stars (MiMeS) project) have led to significant improvements in both our observational and theoretical understanding of the underlying physics governing massive stars. In this article I review recent advances in the field of stellar magnetism of massive stars acquired using spectropolarimetry.
Revealing the Mass Loss Structures of Four Key Massive Binaries Using Optical Spectropolarimetry
Authors: Lomax Jamie R.
Published: January 2015

The majority of massive stars are members of binary systems. However, in order to understand their evolutionary pathways, mass and angular momentum loss from these systems needs to be well characterized. Self-consistent explanations for their behavior across many wavelength regimes need to be valid in order to illuminate key evolutionary phases. I present the results of linear spectropolarimetric studies of three key binaries (β Lyrae, V356 Sgr, V444 Cyg, and WR 140) which reveal important geometric information about their circumstellar material. β Lyrae exhibits a repeatable discrepancy between secondary eclipse in the total and polarized light curves that indicates an accretion hot spot has formed on the edge of the disk in the system. The existence of this hot spot and its relationship to bipolar outflows within the system is important in the understanding of mass transfer dynamics in Roche-lobe overflow binaries. Preliminary work on V356 Sgr suggests the system maybe surrounded by a common envelope. V444 Cyg shows evidence that its shock creates a cone with a large opening angle of missing material around the WN star. This suggests the effects of radiative inhibition or braking, can be significant contributors to the location and shape of the shock within colliding wind binaries. The intrinsic polarization component of WR 140 is likely due to the formation of dust within the system near periastron passages. Continued work on these and additional objects will provide new and important constraints on the mass loss structures within binary systems.
Constraining general massive-star physics by exploring the unique properties of magnetic O-stars: Rotation, macroturbulence & sub-surface convection
Authors: Sundqvist Jon O.
Published: January 2015

A quite remarkable aspect of non-interacting O-stars with detected surface magnetic fields is that they all are very slow rotators. This paper uses this unique property to first demonstrate that the projected rotational speeds of massive, hot stars, as derived using current standard spectroscopic techniques, can be severely overestimated when significant “macroturbulent” line-broadening is present. This may, for example, have consequences for deriving the statistical distribution of rotation rates in massive-star populations. It is next shown how such macroturbulence (seemingly a universal feature of hot, massive stars) is present in all but one of the magnetic O-stars, namely NGC 1624-2. Assuming then a simple model in which NGC 1624-2's exceptionally strong, large-scale magnetic field suppresses atmospheric motions down to layers where the magnetic and gas pressures are comparable, first empirical constraints on the formation depth of this enigmatic hot-star macroturbulence is derived. The results suggest it originates in the thin sub-surface convection zone of massive stars, consistent with a physical origin due to, e.g., stellar pulsations excited by the convective motions.
Linear line spectropolarimetry as a new window to measure 2D and 3D wind geometries
Authors: Vink Jorick S.
Published: January 2015

Various theories have been proposed to predict how mass loss depends on the stellar rotation rate, both in terms of its strength, as well as its latitudinal dependence, crucial for our understanding of angular momentum evolution. Here we discuss the tool of linear spectropolarimetry that can probe the difference between mass loss from the pole versus the equator. Our results involve several groups of O stars and Wolf-Rayet stars, involving Oe stars, Of?p stars, Onfp stars, as well as the best candidate gamma-ray burst progenitors identified to date.
Spectropolarimetric study of selected cool supergiants
Authors: Butkovskaya V. , Plachinda S. , Baklanova D.
Published: January 2015

Cool supergiants offer a good opportunity to study the interplay of magnetic fields and stellar evolution. We present the results of spectropolarimetric study of the cool supergiants and classical Cepheids η Aql and ζ Gem.
Impact of rotation on the geometrical configurations of fossil magnetic fields
Authors: Emeriau C. , Mathis S.
Published: January 2015

The MiMeS project demonstrated that a small fraction of massive stars (around 7%) presents large-scale, stable, generally dipolar magnetic fields at their surface. These fields that do not present any evident correlations with stellar mass or rotation are supposed to be fossil remnants of the initial phases of stellar evolution. They result from the relaxation to MHD equilibrium states, during the formation of stable radiation zones, of initial fields resulting from a previous convective phase. In this work, we present new theoretical results, where we generalize previous studies by taking rotation into account. The properties of relaxed fossil fields are compared to those obtained when rotation is ignored. Consequences for magnetic fields in the radiative envelope of rotating early-type stars and their stability are finally discussed.
Spectropolarimetry and modeling of WR156
Authors: Maryeva Olga
Published: January 2015

For the first time spectropolarimetric observations of Wolf-Rayet star WR156 (WN8h) were conducted. Medium resolution spectropolarimetric data in the range of 3500-7200 ÅÅ were obtained at Russian 6-m telescope of Special Astrophysical Observatory (SAO RAS). These data show that the light from the star is significantly polarized, with the degree of polarization P=1.38±0.06%, and the position angle Θ=77.4°±1.2°. This polarization, most probably, has an interstellar origin, as its magnitude and orientation are similar to the ones of field stars. Also, we present results of numerical modeling of WR156 atmosphere performed using cmfgen code. According to it, WR156 is the richest hydrogen Wolf-Rayet star of WN8 type in the Galaxy.
Magnetic main sequence stars as progenitors of blue supergiants
Authors: Petermann I. , Castro N. , Langer N.
Published: January 2015

Blue supergiants (BSGs) to the right the main sequence band in the HR diagram can not be reproduced by standard stellar evolution calculations. We investigate whether a reduced convective core mass due to strong internal magnetic fields during the main sequence might be able to recover this population of stars. We perform calculations with a reduced mass of the hydrogen burning convective core of stars in the mass range 3–30 M⊙ in a parametric way, which indeed lead to BSGs. It is expected that these BSGs would still show large scale magnetic fields in the order of 10 G.
Massive Star Astrophysics with the new Magellanic Cloud photometric survey MCSF
Authors: Bomans Dominik J. , Becker Alexander , Weis Kerstin
Published: January 2015

Surveys of the resolved stellar content of entire galaxies are the natural tool to study fast evolutionary phases of massive stars. Therefore we launched the Magellanic Clouds Massive Stars and Feedback Survey (MCSF) and periodically imaged for 3 years the entire Small and Large Magellanic Cloud in u, B, V, R, I and Hα, [Oiii], [Sii] using the twin telescope RoBoTT at the University Observatory of the Ruhr-University Bochum at Cerro Armazones, Chile. Observations with short exposure times are included to ensure brightest stars not to be saturated, yielding a full coverage in luminosity. With this unique dataset we can study the massive stellar populations up to MB ∼ −10 mag and their feedback. Upon completion a high quality photometric and spatially complete catalog of the Magellanic Clouds will be established which is be comparable (or even beyond) the quality of HST based photometry of nearby galaxies.
Asteroseismology and spectropolarimetry: opening new windows on the internal dynamics of massive stars
Authors: Mathis S. , Neiner C.
Published: January 2015

In this article, we show how asteroseismology and spectropolarimetry allow to probe dynamical processes in massive star interiors. First, we give a summary of the state-of-the-art. Second, we recall the MHD mechanisms that take place in massive stars. Next, we show how asteroseismology gives strong constraints on the internal mixing and transport of angular momentum while spectropolarimetry allows to unravel the role played by magnetic fields.
The Massive Star Population at the Center of the Milky Way
Authors: Najarro Francisco , de la Fuente Diego , Geballe Tom R. , Figer Don F. , Hillier D. John
Published: January 2015

Recent detection of a large number of apparently isolated massive stars within the inner 80 pc of the Galactic Center has raised fundamental questions regarding massive star formation in a such a dense and harsh environment. Are these isolated stars the results of tidal interactions between clusters, are they escapees from a disrupted cluster, or do they represent a new mode of massive star formation in isolation? Noting that most of the isolated massive stars have spectral analogs in the Quintuplet Cluster, we have undertaken a combined analysis of the infrared spectra of both selected Quintuplet stars and the isolated objects using Gemini North spectroscopy. We present preliminary results, aiming at α-elements vs iron abundances, stellar properties, ages and radial velocities which will differentiate the top-heavy and star-formation scenarios.
Combining seismology and spectropolarimetry of hot stars
Authors: Neiner Coralie , Briquet Maryline , Mathis Stéphane , Degroote Pieter
Published: January 2015

Asteroseismology and spectropolarimetry have allowed us to progress significantly in our understanding of the physics of hot stars over the last decade. It is now possible to combine these two techniques to learn even more information about hot stars and constrain their models. While only a few magnetic pulsating hot stars are known as of today and have been studied with both seismology and spectropolarimetry, new opportunities - in particularKepler2 and BRITE - are emerging and will allow us to rapidly obtain new combined results.
Circumstellar Environments of MYSOs Revealed by IFU Spectroscopy
Authors: Navarete F. , Damineli A. , Barbosa C. L. , Blum R. D.
Published: January 2015

Formation of massive stars (M > 8 M⊙) is still not well understood and lacks of observational constraints. We observed 7 MYSO candidates using the NIFS spectrometer at Gemini North Telescope to study the accretion process at high angular resolution (~ 50 mas) and very closer to the central star. Preliminary results for 2 sources have revealed circumstellar structures traced by Brackett-Gamma, CO lines and extended H2 emission. Both sources present kinematics in the CO absorption lines, suggesting rotating structures. The next step will derive the central mass of each source by applying a keplerian model for these CO features.
New insights on Be shell stars from modelling their Hα emission profiles
Authors: Silaj J. , Jones C. E. , Sigut T. A. A. , Tycner C.
Published: January 2015

Be shell stars are believed to be ordinary Be stars seen edge-on, which makes them particularly desirable objects for study since the uncertainty in the inclination of the rotation axis is largely eliminated. We have recently modelled high resolution Hα spectroscopic observations for eight Be shell stars, using the non-local thermodynamical equilibrium radiative transfer codeBedisk(Sigut & Jones 2007) and the new spectral synthesis packageBeray(Sigut 2011). Generally, we confirm that these systems are oriented at high inclination angles, although we find that they are not necessarily as close to edge-on as initially expected.
Interferometry of massive stars: the next step
Authors: Stee Ph. , Meilland A. , Creevey O. L.
Published: January 2015

We present some new and interesting results on the complementarity between asteroseismology and interferometry, the detection of non-radial pulsations in massive stars and the possibility for evidencing differential rotation on the surface of Bn stars. We also discuss the curretn interferometric facilities, namely the Very Large Telescope Interferometer (VLTI)/AMBER, VLTI/MIDI, VLTI/PIONIER within the European Southern Observatory (ESO) context and the Center for High Angular Resolution Astronomy (CHARA) array with their current limitations. The forthcoming second-generation VLTI instruments GRAVITY and MATISSE are presented as well as the FRIEND prototype in the visible spectral domain and an update of the Navy Precision Optical Interferometer (NPOI). A conclusion is presented with a special emphasis on the foreseen difficulties for a third generation of interferometric instruments within the (budget limited) Extremely Large Telescope framework and the need for strong science cases to push a future visible beam combiner.
Stellar Models: What is the future direction?
Authors: ud-Doula Asif
Published: January 2015

This was one of two general discussions at the conference and it focussed primarily on stellar modelling. In particular, we were interested in the quality of the models, how we can check the models and what the direction of future modelling will be given the rise in popularity of MESA.
“Doing God” in Number 10: British Prime Ministers, Religion, and Political Rhetoric
Authors: Crines Andrew S. , Theakston Kevin
Published: January 2015

This article analyses British prime ministers' use of religious language and their own religious beliefs in their political rhetoric. This is used to justify policy, support their ideological positions, present a public persona, and cultivate their personal ethical appeal and credibility as values-driven political leaders. The focus is on the use and the nature of the religious arguments of Margaret Thatcher, Tony Blair, Gordon Brown and David Cameron. As political leaders, British prime ministers are aware of the need to modify and tailor their language in response to changing audiences and contexts. “Doing God” is a difficult and risky rhetorical strategy for British prime ministers but it increasingly has the potential to yield political benefits.
Vom Aufbruch ins Ungewohnte
Authors: Kraft Melanie , Eberhardt Doris
Published: January 2015

In einem Workshop wird aufgezeigt, wie plastisches Gestalten mit dem Ziel ästhetischer Bildung in der Pflege eingesetzt werden kann. Es treten besonders zwei Aspekte in den Vordergrund: Die Phasen des kreativen Prozesses, der sich wie ein roter Faden durch den Workshop zieht und die Wahrnehmungsschulung als konstitutives Moment ästhetischer Lernprozesse. Ebenfalls werden die in der Regel fehlenden Vorkenntnisse bzw. Erfahrungen der Zielgruppe mit künstlerischem Arbeiten berücksichtigt.
Non-social adaptation defers a tragedy of the commons in Pseudomonas aeruginosa quorum sensing
Authors: Asfahl Kyle L , Walsh Jessica , Gilbert Kerrigan , Schuster Martin
Published: January 2015

In a process termed quorum sensing (QS), the opportunistic bacterial pathogen Pseudomonas aeruginosa uses diffusible signaling molecules to regulate the expression of numerous secreted factors or public goods that are shared within the population. But not all cells respond to QS signals. These social cheaters typically harbor a mutation in the QS receptor gene lasR and exploit the public goods produced by cooperators. Here we show that non-social adaptation under growth conditions that require QS-dependent public goods increases tolerance to cheating and defers a tragedy of the commons. The underlying mutation is in the transcriptional repressor gene psdR. This mutation has no effect on public goods expression but instead increases individual fitness by derepressing growth-limiting intracellular metabolism. Even though psdR mutant populations remain susceptible to invasion by isogenic psdR lasR cheaters, they bear a lower cheater load than do wild-type populations, and they are completely resistant to invasion by lasR cheaters with functional psdR. Mutations in psdR also sustain growth near wild-type levels when paired with certain partial loss-of-function lasR mutations. Targeted sequencing of multiple evolved isolates revealed that mutations in psdR arise before mutations in lasR, and rapidly sweep through the population. Our results indicate that a QS-favoring environment can lead to adaptations in non-social, intracellular traits that increase the fitness of cooperating individuals and thereby contribute to population-wide maintenance of QS and associated cooperative behaviors.
UCHL1 provides diagnostic and antimetastatic strategies due to its deubiquitinating effect on HIF-1α
Authors: Goto Yoko , Zeng Lihua , Yeom Chan Joo , Zhu Yuxi , Morinibu Akiyo , Shinomiya Kazumi , Kobayashi Minoru , Hirota Kiichi , Itasaka Satoshi , Yoshimura Michio , Tanimoto Keiji , Torii Masae , Sowa Terumasa , Menju Toshi , Sonobe Makoto , Kakeya Hideaki , Toi Masakazu , Date Hiroshi , Hammond Ester M. , Hiraoka Masahiro , Harada Hiroshi
Published: January 2015

Hypoxia-inducible factor 1 (HIF-1) plays a role in tumour metastases; however, the genes that activate HIF-1 and subsequently promote metastases have yet to be identified. Here we show that Ubiquitin C-terminal hydrolase-L1 (UCHL1) abrogates the von Hippel–Lindau-mediated ubiquitination of HIF-1α, the regulatory subunit of HIF-1, and consequently promotes metastasis. The aberrant overexpression of UCHL1 facilitates distant tumour metastases in a HIF-1-dependent manner in murine models of pulmonary metastasis. Meanwhile, blockade of the UCHL1–HIF-1 axis suppresses the formation of metastatic tumours. The expression levels of UCHL1 correlate with those of HIF-1α and are strongly associated with the poor prognosis of breast and lung cancer patients. These results indicate that UCHL1 promotes metastases as a deubiquitinating enzyme for HIF-1α, which justifies exploiting it as a prognostic marker and therapeutic target of cancers.
Association between PLCE1 rs2274223 A > G polymorphism and cancer risk: proof from a meta-analysis
Authors: Xue Wenji , Zhu Meiling , Wang Yiwei , He Jing , Zheng Leizhen
Published: January 2015

Phospholipase C epsilon 1 (PLCE1) plays an important role in cell growth, differentiation and oncogenesis. An increasing number of individual studies have investigated the association between PLCE1 rs2274223 polymorphism and cancer risk, but the conclusions are inconclusive. To obtain a comprehensive conclusion, we performed a meta-analysis of 22 studies with 13188 cases and 14666 controls. The pooled results indicated that PLCE1 rs2274223 A > G polymorphism was associated with an increased risk of overall cancer (G vs. A: OR = 1.15, 95% CI = 1.06–1.25; GG vs. AA: OR = 1.30, 95% CI = 1.10–1.55; GA vs. AA: OR = 1.18, 95% CI = 1.08–1.30; GG/GA vs. AA: OR = 1.20, 95% CI = 1.08–1.32; GG vs. GA/AA: OR = 1.22, 95% CI = 1.04–1.42). The stratification analysis showed the polymorphism was significantly associated with an increased risk of esophageal squamous cell carcinoma (ESCC) other than gastric cancer (GC), especially among the subgroups of Asian, high quality score, sample size > 1000 and the studies consistent with Hardy-Weinberg equilibrium (HWE). This meta-analysis demonstrated that PLCE1 rs2274223 A > G polymorphism may be associated with increased susceptibility to cancer, especially for ESCC. However, due to the substantial heterogeneities across the studies, the conclusion might be not conclusive that need more studies to confirm.
Reactions of allylic radicals that impact molecular weight growth kinetics
Authors: Wang Kun , Villano Stephanie M. , Dean Anthony M.
Published: January 2015

The reactions of allylic radicals have the potential to play a critical role in molecular weight growth (MWG) kinetics during hydrocarbon oxidation and/or pyrolysis.
Synthesis of biomass-derived methylcyclopentane as a gasoline additive via aldol condensation/hydrodeoxygenation of 2,5-hexanedione
Authors: Sacia Eric R. , Deaner Matthew H. , Louie Ying “Lin” , Bell Alexis T.
Published: January 2015

We demonstrate that 2,5-hexanedione, a biomass-derived molecule, can be converted selectively in two steps to methylcyclopentane, an exceptional gasoline additive.
Isotopic analysis of Cu in blood serum by multi-collector ICP-mass spectrometry: a new approach for the diagnosis and prognosis of liver cirrhosis?
Authors: Costas-Rodríguez Marta , Anoshkina Yulia , Lauwens Sara , Van Vlierberghe Hans , Delanghe Joris , Vanhaecke Frank
Published: January 2015

The isotopic composition of blood serum Cu has been investigated as a potential parameter for the diagnosis and prognosis of liver cirrhosis.
Microwave-assisted synthesis of 6,6′-(aryl(alkyl)methylene)bis(2,4-dialkylphenol) antioxidants catalyzed by multi-sulfonated reduced graphene oxide nanosheets in water
Authors: Naeimi Hossein , Golestanzadeh Mohsen
Published: January 2015

Sulfonated reduced graphene oxide nanosheets were characterized and employed in the synthesis of bisphenolic antioxidants in water under microwave conditions.
Effect of water state and polymer chain motion on the mechanical properties of a bacterial cellulose and polyvinyl alcohol (BC/PVA) hydrogel
Authors: Li Lifeng , Ren Li , Wang Lin , Liu Sa , Zhang Yongrou , Tang Liqun , Wang Yingjun
Published: January 2015

The effects of water state and polymer chain motion on the mechanical property of bacterial cellulose and a polyvinyl alcohol hydrogel.
Synthesis of multiarm star copolymers based on polyglycerol cores with polylactide arms and their application as nanocarriers
Authors: Adeli M. , Namazi H. , Du F. , Hönzke S. , Hedtrich S. , Keilitz J. , Haag R.
Published: January 2015

Hyperbranched polyglycerol (hPG) with two different molecular weights (hPG2400and hPG8000) was used as a macroinitiator for the polymerization of lactide.
Biology-oriented development of novel lipophilic antioxidants with neuroprotective activity
Authors: Silva T. , Bravo J. , Summavielle T. , Remião F. , Pérez C. , Gil C. , Martínez A. , Borges F.
Published: January 2015

Discovery of hydroxycinnamic acid derivatives with enhanced in lipophilicity, blood brain barrier permeability and neuroprotective potential.
Low-temperature synthesis of macroporous LiTi2(PO4)3/C with superior lithium storage properties
Authors: El-Shinawi Hany , Janek Jürgen
Published: January 2015

A macroporous LiTi2(PO4)3/C nanocomposite is prepared using a calcination-temperature as low as 550 °C, and exhibits superior cycle performance in lithium batteries.
Thermal oxidation reaction process and oxidation kinetics of abietic acid
Authors: Ren Fan , Zheng Yan-Fei , Liu Xiong-Min , Yang Qiong-Qiong , Zhang Qiang , Shen Fang
Published: January 2015

A kinetic study on the oxidation of abietic acid, providing new basic data.
Evaluation of electrospun polymer–Fe3O4nanocomposite mats in malachite green adsorption
Authors: Savva Ioanna , Marinica Oana , Papatryfonos Charalambos A. , Vekas Ladislau , Krasia-Christoforou Theodora
Published: January 2015

Magnetoactive polymer-based electrospun fibers containing Fe3O4nanoparticles, were successfully employed as adsorbents for malachite green oxalate in aqueous media.
Preparation of imidazolium-type ionic liquids containing silsesquioxane frameworks and their thermal and ion-conductive properties
Authors: Ishii Takuhiro , Enoki Toshiaki , Mizumo Tomonobu , Ohshita Joji , Kaneko Yoshiro
Published: January 2015

Imidazolium-type ionic liquids containing a random-structured (Im-Random-SQ-IL) and a cage-like (Im-Cage-SQ-IL) oligosilsesquioxanes were successfully prepared by hydrolytic condensation of MTICl in TFSI solutions in water and water/methanol solution, respectively.
Facile potentiostatic preparation of functionalized polyterthiophene-anchored graphene oxide as a metal-free electrocatalyst for the oxygen reduction reaction
Authors: Naveen M. Halappa , Noh Hui-Bog , Hossain Md Shahriar Al , Kim Jung Ho , Shim Yoon-Bo
Published: January 2015

A new polyterthiophene-anchored GO electrocatalyst was prepared. The C–N bonds of the polymer served as active sites for the ORR catalyst.
Palladium-catalysed carbonylative α-arylation of nitromethane
Authors: Lian Zhong , Friis Stig D. , Skrydstrup Troels
Published: January 2015

A palladium-catalysed approach to α-nitroketonesviacarbonylative α-arylation of nitromethane is presented, thus providing easy access to key intermediates and important heterocycles.
enantio-Enriched CPL-active helicene–bipyridine–rhenium complexes
Authors: Saleh Nidal , Srebro Monika , Reynaldo Thibault , Vanthuyne Nicolas , Toupet Loïc , Chang Victoria Y. , Muller Gilles , Williams J. A. Gareth , Roussel Christian , Autschbach Jochen , Crassous Jeanne
Published: January 2015

Incorporation of a rhenium atom within an extended helical π-conjugated bi-pyridine system leads to the first examples of rhenium-based phosphors that exhibit circularly polarized luminescence.
Breaking the co-operation between bystander T-cells and natural killer cells prevents the development of immunosuppression after traumatic skeletal muscle injury in mice
Authors: Wirsdörfer Florian , Bangen Jörg M. , Pastille Eva , Hansen Wiebke , Flohé Stefanie B.
Published: January 2015

After traumatic skeletal muscle injury, natural killer (NK) cells are recruited to the draining lymph node in a TLR4 (toll-like receptor 4)–myeloid differentiation factor 88 (MyD88)-dependent manner and impair the development of specific T-cell responses. The suppressed T-cell function might increase the susceptibility of severely injured patients to nosocomial infections.
Effects of Coaching on Educators' and Preschoolers' Use of References to Print and Phonological Awareness During a Small-Group Craft/Writing Activity
Authors: Milburn Trelani F. , Hipfner-Boucher Kathleen , Weitzman Elaine , Greenberg Janice , Pelletier Janette , Girolametto Luigi
Published: January 2015

Purpose

The current study investigated the effects of coaching as part of an emergent literacy professional development program to increase early childhood educators' use of verbal references to print and phonological awareness during interactions with children.

Method

Thirty-one educators and 4 children from each of their classrooms (N= 121) were randomly assigned to an experimental group (21 hr of in-service workshops plus 5 coaching sessions) and a comparison group (workshops alone). The in-service workshops included instruction on how to talk about print and phonological awareness during a post-story craft/writing activity. All educators were video-recorded during a 15-min craft/writing activity with a small group of preschoolers at pretest and posttest. All videotapes were transcribed and coded for verbal references to print and phonological awareness by the educators and children.

Results

Although at posttest, there were no significant group differences in the educators' or the children's references to print as measured by rate per minute, both the educators and the children in the experimental group used a significantly higher rate per minute of references to phonological awareness relative to the comparison group.

Conclusion

Professional development that included coaching with a speech-language pathologist enabled educators and children to engage in more phonological awareness talk during this activity.
Uniplanar differentially driven UWB polarisation diversity antenna with band‐notched characteristics
Authors: Huang He , Liu Ying , Gong Shuxi
Published: January 2015

A differentially driven ultra‐wideband (UWB) polarisation diversity antenna with dual notch bands is presented for the first time. The antenna consists of a chamfer square slot and two differential pairs being orthogonal to achieve polarisation diversity performance over the UWB. The proposed antenna has a wide impedance bandwidth from 2.75 to more than 11 GHz for differential reflection coefficients less than −10 dB, and a high differential port‐to‐port isolation of less than −40 dB. Dual band‐rejected operation to filter the 3.5 GHz WiMAX and 5.5 GHz WLAN bands is obtained by employing two different methods. All these features make the proposed antenna very suitable for applications in UWB wireless communication systems.
Circularly polarised cut ring microstrip antenna
Authors: Yi Yang , Jian‐ying Li , Kun Wei , Rui Xu , Guang‐wei Yang
Published: January 2015

A circularly polarised cut ring microstrip antenna is proposed. The antenna realises circular polarisation and obtains high gain. It is characterised by simple construction and feed mode, and it is not sensitive to the feeding position, which means it is easy to be matched. A study of the different geometric parameters of the antenna and their effect on the performance of the antenna has been conducted. The designed antenna works at about 3.4 GHz, and the results show good performance with a −10 dB return loss bandwidth of ∼19.6%, a 3 dB axial ratio a bandwidth of ∼4.2% and a circularly polarised gain of about 10.97 dB. The measured results agree well with the simulated results.
Application of fast cross‐correlation algorithms
Authors: Byard K.
Published: January 2015

Cross‐correlation of binary sequences is a technique used in many applications. A method is presented whereby fast cross‐correlation can be employed in applications that initially use the parameters of sequences derived from difference sets. The simple idea is to replace the difference set sequence with a sequence that has similar parameters, but for which a fast cross‐correlation method exists. Experimental tests using a computer confirm the time savings of this method.
Periodic and aperiodic pulse generation using optically injected DFB laser
Authors: Aldaya I. , Gosset C. , Wang C. , Campuzano G. , Grillot F. , Castañón G.
Published: January 2015

Generation of optical pulse trains using semiconductor lasers has attracted significant attention due to their applications in optical communications and signal processing. A pulse generator based on the nonlinear dynamics of an optically injected distributed feedback laser is presented. The proposed system does not require electrical excitation and can be configured to operate in a periodic or aperiodic pulsation regime by controlling the injection conditions. Experiments show periodic pulsation with a repetition rate of 1.034 GHz and aperiodic pulsation with an average repetition rate of 5.618 GHz.
Device‐to‐device channel measurements and models: a survey
Authors: Cheng Xiang , Li Yan , Ai Bo , Yin Xuefeng , Wang Qi
Published: January 2015

Channel measurements and modelling have been long considered as the foundation for effective and efficient wireless communication system designs. Recently, there has been an explosive growth of research work dedicated to the so‐called device‐to‐device (D2D) communications. In the mean time, however, measurements and modelling of D2D channels seem to somewhat fall behind. To promote research on these aspects, in this study, the authors provide a critical overview of the current state of research on D2D channels, and comprehensively discuss future trends and research directions.
Le Fort I Approach for Midline Tumors of the Palate
Authors: de Cevallos Jorge Guiñales Díaz , Carretero Jose L. Cebrián , de Vera Jose L. Del Castillo Pardo , García Miguel Burgueño
Published: January 2015

Midline tumors of the palate may represent a challenge for the maxillofacial surgeon. Their resection and immediate reconstruction could be hindered when a simply intraoral approach is selected. The Le Fort I downfracture approach represents an ideal technique for the management of this tumors, simplifying their resection, ensuring a tumor-free margin, and allowing their reconstruction with a temporal muscle flap. A review of this procedure is presented, highlighting the technical keys and its principal advantages.
Photoluminescence study of Be-acceptors in GaInNAs epilayers
Authors: Tsai Y. , Barman B. , Scrace T. , Fukuda M. , Whiteside V. R. , Sellers I. R. , Leroux M. , Khalfioui M. Al , Petrou A.
Published: January 2015

We have studied Be-acceptors in a p-type GaInNAs epilayer using magneto-luminescence spectroscopy. The band edge photoluminescence (PL) spectra at T = 7 K contain two features: the first is associated with the free exciton while the second with the conduction band to acceptor (CB  →  A) transition. The intensity of the latter decreases with increasing temperature while the excitonic feature survives up to T = 250 K. From the energies of the two PL features, as well as the exciton binding energy in GaInNAs, we determined the Be-acceptor binding energy to be equal to 42 meV. The energy of the CB  →  A feature varies linearly with magnetic field B and has a slope of 5.5×10−4 eV/T.
Influence of substrate temperature on the crystalline quality of AlN layers deposited by RF reactive magnetron sputtering
Authors: Kumada Tomoyuki , Ohtsuka Makoto , Fukuyama Hiroyuki
Published: January 2015

Aluminum nitride (AlN) is a promising material for use in applications such as ultraviolet light-emitting diodes and surface acoustic wave devices. In this study, AlN layers were fabricated on nitrided sapphire substrates using radio-frequency (RF) reactive magnetron sputtering. An AlN layer sputtered in 50 vol% N2 with a sputter power of 900 W at 823 K exhibited X-ray rocking curves for AlN (0002) and (10-12) with the best full width at half-maximum of 61 and 864 arcsec, respectively. The c-axis lattice constant of the AlN layers expanded with increasing substrate temperature because of the peening effect and thermal expansion difference between the AlN layer and sapphire substrate. Based on the results obtained here combined with those of our previous studies, a model explaining the roles of sputtering parameters in AlN layer growth using RF reactive sputtering was developed.
Asymmetry of Photoelectron Angular Distributions in Molecules by Intense Attosecond Extreme Ultraviolet Laser Pulses
Authors: Yu Hua-ming , Yuan Kai-jun , Sun Zhi-gang
Published: January 2015

We present photoelectron angular distribution of the aligned molecular ion H2+ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of time-dependent Schrödinger equations. Photoionization from a superposition state of the ground 1sσg and the excited 2pσu states with pulses at photon energies above the ionization potential, ħω>Ip, and intensity 1014 W/cm2, yields pulse duration dependent asymmetry of photoelectron angular distributions. We attribute the asymmetry to the periodical oscillation of the coherent electron wave packets, resulting from the interference of the two electronic states. For the processes with long pulse durations, such duration dependence is absent and symmetric angular distributions are obtained.
Droplet Pattern Formation and Translation in New Microfluidic Flow-Focusing Devices
Authors: Xu Hua-guo , Liang Hao-jun
Published: January 2015

We conducted experiments on specially designed microfluidic chips that generate droplets through a microfluidic flow-focusing approach. The fluid flow in the microfluidic channel produced a shear flow field at low Reynolds numbers. The droplets in the microfluidic system exhibited special droplet pattern formations similar to periodic crystal-like lattices because of the competition between shear forces and surface tension. By adjusting the flow rate ratio of the water (droplet phase) to oil (continuous phase) phases and changing the outlet channel widths, the droplets formed monolayer dispersion to double-layer formation to monolayer squeezing when the outlet channel widths were 250 or 300 µm. We also obtained droplets with monolayer dispersion, three-layer arrangements, double-layer squeezing, and monolayer squeezing when the outlet channel width was 350 µm. The outlet channel width was increased to 400 µm, and four-layer arrangements were observed. We also studied the translation of droplet formation, which resulted in a detailed strategy to control drop size and droplet pattern formation for emulsification in microfluidic devices. We expect that our strategy can provide theoretical guidance to synthesize dispersion or polydisperse colloid particles.
Conversion of Cellulose to 5-Hydroxymethylfurfural in Water-Tetrahydrofuran and Byproducts Identification
Authors: Shi Ning , Liu Qi-ying , Wang Tie-jun , Zhang Qi , Tu Jun-ling , Ma Long-long
Published: January 2015

Conversion of cellulose into platform chemical 5-hydroxymethylfurfural (HMF) in water-tetrahydrofuran (THF) co-solvents under acidic condition was studied. 38.6% of HMF was obtained with low cellulose concentration of 2.4wt%, but levulinic acid (LA) and solid humins became the main products with high cellulose concentration. The soluble byproducts were analyzed by high performance liquid chromatography/multiple stage tandem mass spectrometry, and chemicals with formula of C9H16O4, C10H14O4, C11H12O4, C12H10O5 and C12H16O8 were detected. THF could participate in the reaction via ring-opening into 1,4-butanediol followed by esterification with LA into C9H16O4 or etherification with HMF into C10H14O4. C11H12O4 was formed by esterification of HMF with LA, C12H10O5 was formed by self-etherification of HMF, while C12H16O8 was formed by acetalization of HMF with glucose. Self-etherification of HMF and etherification of HMF with 1,4-butanediol were identified as two main side reactions.