bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fitting peculiar spectral profiles in He I 10830 Å absorption features
Authors: González Manrique S. J. , Kuckein C. , Pastor Yabar A. , Collados M. , Denker C. , Fischer C. E. , Gömöry P. , Diercke A. , Bello González N. , Schlichenmaier R. , Balthasar H. , Berkefeld T. , Feller A. , Hoch S. , Hofmann A. , Kneer F. , Lagg A. , Nicklas H. , Orozco Suárez D. , Schmidt D. , Schmidt W. , Sigwarth M. , Sobotka M. , Solanki S. K. , Soltau D. , Staude J. , Strassmeier K. G. , Verma M. , Volkmer R. , von der Lühe O. , Waldmann T. 
Published: November 2016

AbstractThe new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple‐component profiles are more commonly observed with these instruments. Particularly, the Hei 10830 Å triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the Hei 10830 Å triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5‐m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double‐Lorentzian fitting technique using Levenberg‐Marquardt least‐squares minimization. This technique is very simple and much faster than inversion codes. Line‐of‐sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub‐ and supersonic downflow velocities of up to 32km s–1 for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solar eruptions: The CME‐flare relationship
Authors: Vršnak B. 
Published: November 2016

AbstractCoronal mass ejections (CMEs), caused by large‐scale eruptions of the coronal magnetic field, often are accompanied by a more localized energy release in the form of flares, as a result of dissipative magnetic‐field reconfiguration. Morphology and evolution of such flares, also denoted as dynamical flares are often explained as a consequence of reconnection of the arcade magnetic field, taking place below the erupting magnetic flux rope. A close relationship of the CME acceleration and the flare energy release is evidenced by various statistical correlations between parameters describing CMEs and flares, as well as by the synchronization of the CME acceleration phase with the impulsive phase of the associated flare. Such behavior implies that there must be a feedback relation between the dynamics of the CME and the flare‐associated reconnection process. From the theoretical standpoint, magnetic reconnection affects the CME dynamics in several ways. First, it reduces the tension of the overlying arcade magnetic field and increases the magnetic pressure below the flux rope, and in this way enhances the CME acceleration. Furthermore, it supplies the poloidal magnetic flux to the flux rope, which helps sustaining the electric current in the rope and prolonging the action of the driving Lorentz force to large distances. The role of these processes, directly relating solar flares and CMEs, is illustrated by employing a simple model, where the erupting structure is represented by a curved flux rope anchored at both sides in the dense/inert photosphere, being subject to the kink and torus instability. It is shown that in most strongly accelerated ejections, where values on the order of 10km s–2 are attained, the poloidal flux supplied to the erupting rope has to be several times larger than was the initial flux. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinematical properties of coronal mass ejections
Authors: Temmer M. 
Published: November 2016

AbstractCoronal mass ejections (CMEs) are the most dynamic phenomena in our solar system. They abruptly disrupt the continuous outflow of solar wind by expelling huge clouds of magnetized plasma into interplanetary space with velocities enabling to cross the Sun‐Earth distance within a few days. Earth‐directed CMEs may cause severe geomagnetic storms when their embedded magnetic fields and the shocks ahead compress and reconnect with the Earth's magnetic field. The transit times and impacts in detail depend on the initial CME velocity, size, and mass, as well as on the conditions and coupling processes with the ambient solar wind flow in interplanetary space. The observed CME parameters may be severely affected by projection effects and the constant changing environmental conditions are hard to derive. This makes it difficult to fully understand the physics behind CME evolution, preventing to do a reliable forecast of Earth‐directed events. This short review focusing on observational data, shows recent methods which were developed to derive the CME kinematical profile for the entire Sun‐Earth distance range as well as studies which were performed to shed light on the physical processes that CMEs encounter when propagating from Sun to Earth. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observations of solar X‐ray and EUV jets and their related phenomena
Authors: Innes D. E. , Bučík R. , Guo L.‐J. , Nitta N. 
Published: November 2016

AbstractSolar jets are fast‐moving, elongated brightenings related to ejections seen in both images and spectra on all scales from barely visible chromospheric jets to coronal jets extending up to a few solar radii. The largest, most powerful jets are the source of type III radio bursts, energetic electrons and ions with greatly enhanced 3He and heavy element abundances. The frequent coronal jets from polar and equatorial coronal holes may contribute to the solar wind. The primary acceleration mechanism for all jets is believed to be release of magnetic stress via reconnection; however the energy buildup depends on the jets' source environment. In this review, we discuss how certain features of X‐ray and EUV jets, such as their repetition rate and association with radio emission, depends on their underlying photospheric field configurations (active regions, polar and equatorial coronal holes, and quiet Sun). (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chromospheric activity in sunspot light bridges
Authors: Louis R. E. 
Published: November 2016

AbstractHigh‐resolution filtergrams from Hinode were used to analyse the nature of chromospheric activity over a set of five sunspot light bridges. The broad‐band Ca II H filtergrams depict a variety of phenomena which include large arc‐shaped brightenings, bright patches, and small‐scale jets. These strong brightenings are recurrent over a duration of several hours and appear to be a common attribute of a sunspot light bridge, independent of its photospheric morphology and horizontal flow pattern. Hinode spectro‐polarimetric observations were used to construct far wing magnetograms from the Fe I line at 630.25 nm, which reveal the presence of small‐scale magnetic and velocity inhomogeneities in the photosphere of the light bridges. Although there is strong evidence for a causal relation between the photospheric anomalies and the observed chromospheric activity, the physical mechanism responsible for the latter remains speculative. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectropolarimetric observations of an arch filament system with the GREGOR solar telescope
Authors: Balthasar H. , Gömöry P. , González Manrique Sj. , Kuckein C. , Kavka J. , Kučera A. , Schwartz P. , Vašková R. , Berkefeld T. , Collados Vera M. , Denker C. , Feller A. , Hofmann A. , Lagg A. , Nicklas H. , Orozco Suárez D. , Pastor Yabar A. , Rezaei R. , Schlichenmaier R. , Schmidt D. , Schmidt W. , Sigwarth M. , Sobotka M. , Solanki S.K. , Soltau D. , Staude J. , Strassmeier K. G. , Volkmer R. , von der Lühe O. , Waldmann T. 
Published: November 2016

AbstractArch filament systems occur in active sunspot groups, where a fibril structure connects areas of opposite magnetic polarity, in contrast to active region filaments that follow the polarity inversion line. We used the GREGOR Infrared Spectrograph (GRIS) to obtain the full Stokes vector in the spectral lines Si I λ 1082.7 nm, He I λ 1083.0 nm, and Ca I λ 1083.9 nm. We focus on the near‐infrared calcium line to investigate the photospheric magnetic field and velocities, and use the line core intensities and velocities of the helium line to study the chromospheric plasma. The individual fibrils of the arch filament system connect the sunspot with patches of magnetic polarity opposite to that of the spot. These patches do not necessarily coincide with pores, where the magnetic field is strongest. Instead, areas are preferred not far from the polarity inversion line. These areas exhibit photospheric downflows of moderate velocity, but significantly higher downflows of up to 30 km s–1 in the chromospheric helium line. Our findings can be explained with new emerging flux where the matter flows downward along the field lines of rising flux tubes, in agreement with earlier results. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Daniel K. Inouye Solar Telescope: High‐resolution observing of the dynamic Sun
Authors: Tritschler A. , Rimmele T. R. , Berukoff S. , Casini R. , Kuhn J. R. , Lin H. , Rast M. P. , McMullin J. P. , Schmidt W. , Wöger F. , DKIST Team  
Published: November 2016

AbstractThe 4‐m aperture Daniel K. Inouye Solar Telescope (DKIST) formerly known as the Advanced Technology Solar Telescope (ATST) is currently under construction on Haleakalā (Maui, Hawai'i) projected to start operations in 2019. At the time of completion, DKIST will be the largest ground‐based solar telescope providing unprecedented resolution and photon collecting power. The DKIST will be equipped with a set of first‐light facility‐class instruments offering unique imaging, spectroscopic and spectropolarimetric observing opportunities covering the visible to infrared wavelength range. This first‐light instrumentation suite will include: a Visible Broadband Imager (VBI) for high‐spatial and ‐temporal resolution imaging of the solar atmosphere; a Visible Spectro‐Polarimeter (ViSP) for sensitive and accurate multi‐line spectropolarimetry; a Fabry‐Pérot based Visible Tunable Filter (VTF) for high‐spatial resolution spectropolarimetry; a fiber‐fed Diffraction‐Limited Near Infra‐Red Spectro‐Polarimeter (DL‐NIRSP) for two‐dimensional high‐spatial resolution spectropolarimetry (simultaneous spatial and spectral information); and a Cryogenic Near Infra‐Red Spectro‐Polarimeter (Cryo‐NIRSP) for coronal magnetic field measurements and on‐disk observations of, e.g., the CO lines at 4.7 μm. We will provide an overview of the DKISTs unique capabilities with strong focus on the first‐light instrumentation suite, highlight some of the additional properties supporting observations of transient and dynamic solar phenomena, and touch on some operational strategies and the DKIST critical science plan. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On measurements of the Balmer continuum flux in a solar flare: Analysis of pre‐flare and flare pulsations
Authors: Zapiór M. , Kotrč P. , Oliver R. , Procházka O. , Heinzel P. 
Published: November 2016

AbstractA new ground based device for the measurement of the Balmer continuum flux in solar flares was recently developed and installed at the Ondřejov Observatory. We observed an X1 solar flare on 2014 June 11 during its pre‐flare and impulsive phases using a wide band spectrometer with a cadence of 1 s. The Ensemble Empirical Mode Decomposition (EEMD) of the registered signal was performed. We found damped oscillations with a period of 609 s and damping time of 1478 s. Shorter periods of about 30–120 s were found during the pre‐flare and impulsive phases, but they might be of non‐flare origin
STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma
Authors: Momtaz Saeideh , Niaz Kamal , Maqbool Faheem , Abdollahi Mohammad , Rastrelli Luca , Nabavi Seyed Mohammad 
Published: November 2016

AbstractMelanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347–370, 2017
Small‐Molecule‐Induced and Cooperative Enzyme Assembly on a 14‐3‐3 Scaffold
Authors: den Hamer Anniek , Lemmens Lenne J. M. , Nijenhuis Minke A. D. , Ottmann Christian , Merkx Maarten , de Greef Tom F. A. , Brunsveld Luc 
Published: November 2016

AbstractScaffold proteins regulate cell signalling by promoting the proximity of putative interaction partners. Although they are frequently applied in cellular settings, fundamental understanding of them in terms of, amongst other factors, quantitative parameters has been lagging behind. Here we present a scaffold protein platform that is based on the native 14‐3‐3 dimeric protein and is controllable through the action of a small‐molecule compound, thus permitting study in an in vitro setting and mathematical description. Robust small‐molecule regulation of caspase‐9 activity through induced dimerisation on the 14‐3‐3 scaffold was demonstrated. The individual parameters of this system were precisely determined and used to develop a mathematical model of the scaffolding concept. This model was used to elucidate the strong cooperativity of the enzyme activation mediated by the 14‐3‐3 scaffold. This work provides an entry point for the long‐needed quantitative insights into scaffold protein functioning and paves the way for the optimal use of reengineered 14‐3‐3 proteins as chemically inducible scaffolds in synthetic systems.
Plant‐Mediated Synthesis of Zinc Oxide Supported Nickel‐Palladium Alloy Catalyst for the Selective Hydrogenation of 1,3‐Butadiene
Authors: Huang Jiale , Odoom‐Wubah Tareque , Jing Xiaolian , Sun Daohua , Gu Zhengqiang , Li Qingbiao 
Published: November 2016

AbstractWe report the green synthesis of ZnO‐supported Ni‐Pd alloy nanoparticles for the gas‐phase selective hydrogenation of 1,3‐butadiene. The supported catalysts were synthesized through a simple bioreduction route using Cinnamomum Camphora leaf extract. We used XRD, SEM, TEM, and energy‐dispersive X‐ray spectroscopy to characterize and verify the nature of the catalysts. The results showed that the size of the Ni‐Pd alloy particles was (3.2±0.7), (3.4±0.3), and (3.8±0.6) nm for Ni1Pd1, Ni1Pd3, and Ni3Pd1 respectively. FTIR spectroscopy revealed that the presence of stretching vibrations from C−H, −C=C−, O−H, and −C−O−O groups that remained on the surface and act as stabilizers. The influence of some reaction variables, such as the type of S‐Pd (S=Au, Ag, Ni) bimetallic catalyst, the type of metal oxide support, and the reaction temperature, on the hydrogenation activity and selectivity towards total butene (trans‐2‐butene, 1‐butene, and cis‐2‐butene) is investigated. The bioreduced, supported catalysts showed excellent catalytic activity and selectivity to butene in the selective hydrogenation of 1,3‐butadiene. The calculated total butene selectivity was above 80 % for all supported S1‐Pd1 catalysts compared to 46.92 % for a monometallic Pd/ZnO catalyst. In addition, the Ni1‐Pd1/ZnO catalyst presented the best butene yield of 88.90 %, which was 1.9 times that of the Pd/ZnO catalyst. Moreover, it remained stable over a 10 h durability experiment.
Freestanding Catalyst Layers: A Novel Electrode Fabrication Technique for PEM Fuel Cells via Electrospinning
Authors: Kayarkatte Manoj Krishna , Delikaya Öznur , Roth Christina 
Published: November 2016

AbstractTo propel the commercial success of fuel cells, increased Pt catalyst utilization is preeminent. To achieve this, advanced 3D scaffold electrode architecture with controllable porosity, thickness, etc. should be developed. Here, we present a novel technique for the fabrication of electrode structures through electrospinning, which is not only tailorable, but inexpensive and scalable. The structure is freestanding and contains carbon nanotube‐enforced carbon nanofibers, which give the electrode its structure. Pt is decorated on the surface of the fiber structures through impregnation of a Pt precursor and successive reduction. The electrode structure is hot‐pressed by inserting it between a gas diffusion layer (GDL) and a membrane to form the cathode. The novel fabrication technique is versatile and can be used to prepare electrodes of different morphologies. In this work, we demonstrate the technique by preparing a highly porous network, which shows a very high Pt utilization of approximately 90% for a loading of 0.3 mgPt cm−2. In comparison, a standard electrode prepared via a hot‐spray technique has a catalyst utilization of 60% for the same loading.
Selective B(4)−H Activation of an o‐Carboranylthioamide Based on a Palladium Precursor
Authors: Wang Yin‐Ping , Zhang Long , Lin Yue‐Jian , Li Zhen‐Hua , Jin Guo‐Xin 
Published: November 2016

AbstractPalladium(II)‐induced selective B(4)−H activation of an o‐carboranylthioamide has been developed. A tetranuclear palladium(II) complex has been obtained in high yield with excellent regioselectivity. DFT calculations have confirmed that the B(4)‐borometalate is lower in energy than the corresponding B(3)‐borometalate. The product proved to be a good precursor for target mononuclear or trinuclear B(4)−H activated complexes.
One‐Step Synthesis of Boron Nitride Quantum Dots: Simple Chemistry Meets Delicate Nanotechnology
Authors: Liu Bingping , Yan Shihai , Song Zhongqian , Liu Mengli , Ji Xuqiang , Yang Wenrong , Liu Jingquan 
Published: November 2016

AbstractHerein, a conceptually new and straightforward aqueous route is described for the synthesis of hydroxyl‐ and amino‐functionalized boron nitride quantum dots (BNQDs) with quantum yields (QY) as high as 18.3 % by using a facile bottom‐up approach, in which a mixture of boric acid and ammonia solution was hydrothermally treated in one pot at 200 °C for 12 h. The functionalized BNQDs, with excellent photoluminescence properties, could be easily dispersed in an aqueous medium and applied as fluorescent probes for the detection of ferrous (Fe2+) and ferric (Fe3+) ions with excellent selectivity and low detection limits. The mechanisms for the hydrothermal reaction and fluorescence quenching were also simulated by using density functional theory (DFT), which confirmed the feasibility and advantages of this strategy. It provides a scalable and eco‐friendly method for preparation of BNQDs with good dispersability and could also be generalized to the synthesis of other 2D quantum dots and nanoplates.
Bulky Ytterbium Formamidinates Stabilise Complexes with Radical Ligands, and Related Samarium “Tetracyclone” Chemistry
Authors: Werner Daniel , Zhao Xuefei , Best Stephen P. , Maron Laurent , Junk Peter C. , Deacon Glen B. 
Published: November 2016

AbstractDivalent [Yb(DippForm)2(thf)n] (n=2 (1 a), or 1 (1 b), DippForm=N,N′‐bis(2,6‐diisopropylphenyl)formamidinate) complexes were treated with the ketones: 9‐fluorenone (fn), or 2,3,4,5‐tetraphenylcyclopentadienone (tpc, tetracyclone), giving ketyl complexes: [Yb(DippForm)2(fn.‐O)(thf)] (2), and [Yb(DippForm)2(tpc.‐O)] (3), respectively (ketyl=a radical anion containing a C.−O(−) group. By contrast, when perfluorobenzophenone (pfb) was treated with either 1 a or 1 b, transitory ketyl formation was followed by rapid decomposition through a C−F activation pathway, giving [YbF(DippForm)2(thf)] (4 a) and a highly unusual fluoride/oxide‐bridged species: [Yb5F6O2(DippForm)5] (4 b). The reduction of diketones: 3,5‐di‐tert‐butyl‐1,2‐benzoquinone (tbbq), 9,10‐phenanthrenequinone (phen), or 1,2‐acenaphthenequinone (acen), was also examined giving ketyl complexes: [Yb(DippForm)2(tbbq.‐O2)] (5), [Yb(DippForm)2(phen.‐O2)] (6), and [Yb(DippForm)2(acen.‐O2)(thf)] (7). An unsolvated derivative of 7, namely [Yb(DippForm)2(acen.‐O2)] (8), was obtained from PhMe. All ketyl complexes had suitably elongated C.−O bonds, were stable in both polar and non‐polar solvents—an uncommon trait for rare‐earth ketyl complexes—and, with the exception of 3, showed radical signals in ESR spectra. To investigate the reactivity of the tpc.‐O ketyl complex, 3 was treated with oxidants (CS2, Se) and reducing agents (Mg0, KH, or [SmI2(thf)2]). Thus 3 was oxidised to tpc by Se. Treatment of 3 with KH led to a ligand exchange process giving an unusual diketyl species [Yb(DippForm)(tpc.‐O)2(thf)2] (10), which has two cisoid tpc.‐O− ligands in very close proximity. When treated with [SmI2(thf)2], the tpc.‐O ketyl was further reduced to a dianion (1‐oxido‐2,3,4,5‐tetraphenylcyclopentadianide2−), ({C5Ph4}‐O)2− by [SmI2(thf)2], giving dimeric [{SmI({C5Ph4}‐O)(thf)2}2] (Sm11) and monomeric complexes [YbI(DippForm)2(thf)] (11 b) and [YbI2(DippForm)(thf)2] (11 c). Activated Sm metal reduced neutral tetracyclone to the dianion, ({C5Ph4}‐O)2−, in THF, giving tetranuclear [{SmII2({C5Ph4}‐O)2(thf)3}2] (Sm13). Treatment of Sm13 with iodine in situ provided access to [{SmI({C5Ph4}‐O)(thf)2}2] (Sm11), in good yield.