bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observational Study of an Unusual Cataclysmic Binary 2MASS J16211735+4412541*
Authors: Zola S. , Szkody P. , Ciprini S. , Verrecchia F. , Debski B. , Ogloza W. , Drozdz M. , Reichart D. , Caton D. B. , Hoette V. L. 
Published: December 2017

Abstract
We present results from an observational campaign on the close binary system 2MASS J16211735+4412541 and a preliminary model based on the photometric data gathered during the quiescent and outburst levels. The modeling, done with the Wilson–Devinney code and its improvements, failed to reproduce the observational properties of the system. A secondary minimum obtained within the stellar model that is too shallow, as well as the evidence provided by the spectroscopic observations performed at outburst and quiescence, point toward an accretion disk surrounding one component, likely a white dwarf, as the cause of the outburst. Using a simple disk model, we modeled the observed multicolor light curves taken two (2016 August) and eight (2017 March) months after the outburst. We obtained a reasonable fit to the 2016 August light curves but those from 2017 March cannot be explained with the same parameters. We conclude that J1621 is an eclipsing cataclysmic binary, with an accretion disk still present almost a year after outburst, and not a contact-type system as previously classified. The binary is seen at an inclination of about 84° and there is evidence of changing accretion rates and disk parameters as a result of the outburst. Our results indicate that more cataclysmic variables may be hidden among contact binaries.
Understanding the Links among the Magnetic Fields, Filament, Bipolar Bubble, and Star Formation in RCW 57A Using NIR Polarimetry
Authors: Eswaraiah Chakali , Lai Shih-Ping , Chen Wen-Ping , Pandey A. K. , Tamura M. , Maheswar G. , Sharma S. , Wang Jia-Wei , Nishiyama S. , Nakajima Y. , Kwon Jungmi , Purcell R. , Magalhães A. M. 
Published: December 2017

Abstract
The influence of magnetic fields (B-fields) on the formation and evolution of bipolar bubbles, due to the expanding ionization fronts (I-fronts) driven by the H ii regions that are formed and embedded in filamentary molecular clouds, has not been well-studied yet. In addition to the anisotropic expansion of I-fronts into a filament, B-fields are expected to introduce an additional anisotropic pressure, which might favor the expansion and propagation of I-fronts forming a bipolar bubble. We present results based on near-infrared polarimetric observations toward the central ∼8′ × 8′ area of the star-forming region RCW 57A, which hosts an H ii region, a filament, and a bipolar bubble. Polarization measurements of 178 reddened background stars, out of the 919 detected sources in the JHK

s
bands, reveal B-fields that thread perpendicularly to the filament long axis. The B-fields exhibit an hourglass morphology that closely follows the structure of the bipolar bubble. The mean B-field strength, estimated using the Chandrasekhar–Fermi method (CF method), is 91 ± 8 μG. B-field pressure dominates over turbulent and thermal pressures. Thermal pressure might act in the same orientation as the B-fields to accelerate the expansion of those I-fronts. The observed morphological correspondence among the B-fields, filament, and bipolar bubble demonstrate that the B-fields are important to the cloud contraction that formed the filament, to the gravitational collapse and star formation in it, and in feedback processes. The last one includes the formation and evolution of mid-infrared bubbles by means of B-field supported propagation and expansion of I-fronts. These may shed light on preexisting conditions favoring the formation of the massive stellar cluster in RCW 57A.
Deep HST Imaging in 47 Tucanae: A Global Dynamical Model
Authors: Heyl J. , Caiazzo I. , Richer H. , Anderson J. , Kalirai J. , Parada J. 
Published: December 2017

Abstract
Multi-epoch observations with the Advanced Camera Survey and WFC3 on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within 47 Tucanae. We confront analytic models of the globular cluster with the observed stellar proper motions that probe along the main sequence from just above 0.8–0.1M
⊙ as well as white dwarfs younger than 1 Gyr. One field lies just beyond the half-light radius where dynamical models (e.g., lowered Maxwellian distributions) make robust predictions for the stellar proper motions. The observed proper motions in this outer field show evidence for anisotropy in the velocity distribution as well as skewness; the latter is evidence of rotation. The measured velocity dispersions and surface brightness distributions agree in detail with a rotating anisotropic model of the stellar distribution function with mild dependence of the proper-motion dispersion on mass. However, the best-fitting models underpredict the rotation and skewness of the stellar velocities. In the second field, centered on the core of the cluster, the mass segregation in proper motion is much stronger. Nevertheless the model developed in the outer field can be extended inward by taking this mass segregation into account in a heuristic fashion. The proper motions of the main-sequence stars yield a mass estimate of the cluster of

at a distance of 4.7 kpc. By comparing the proper motions of a sample of giant and subgiant stars with the observed radial velocities we estimate the distance to the cluster kinematically to be 4.29 ± 0.47 kpc.
Systematic Analysis of the Effects of Mode Conversion on Thermal Radiation from Neutron Stars
Authors: Yatabe Akihiro , Yamada Shoichi 
Published: December 2017

Abstract
In this paper, we systematically calculate the polarization in soft X-rays emitted from magnetized neutron stars, which are expected to be observed by next-generation X-ray satellites. Magnetars are one of the targets for these observations. This is because thermal radiation is normally observed in the soft X-ray band, and it is thought to be linearly polarized because of different opacities for two polarization modes of photons in the magnetized atmosphere of neutron stars and the dielectric properties of the vacuum in strong magnetic fields. In their study, Taverna et al. illustrated how strong magnetic fields influence the behavior of the polarization observables for radiation propagating in vacuo without addressing a precise, physical emission model. In this paper, we pay attention to the conversion of photon polarization modes that can occur in the presence of an atmospheric layer above the neutron star surface, computing the polarization angle and fraction and systematically changing the magnetic field strength, radii of the emission region, temperature, mass, and radii of the neutron stars. We confirmed that if plasma is present, the effects of mode conversion cannot be neglected when the magnetic field is relatively weak,

. Our results indicate that strongly magnetized (

) neutron stars are suitable to detect polarizations, but not-so-strongly magnetized (

) neutron stars will be the ones to confirm the mode conversion.
3‐D Modeling of Irregular Volcanic Sources Using Sparsity‐Promoting Inversions of Geodetic Data and Boundary Element Method
Authors: Zhai Guang , Shirzaei Manoochehr 
Published: December 2017

AbstractGeodetic observations of surface deformation associated with volcanic activities can be used to constrain volcanic source parameters and their kinematics. Simple analytical models, such as point and spherical sources, are widely used to model deformation data. The inherent nature of oversimplified model geometries makes them unable to explain fine details of surface deformation. Current nonparametric, geometry‐free inversion approaches resolve the distributed volume change, assuming it varies smoothly in space, which may detect artificial volume change outside magmatic source regions. To obtain a physically meaningful representation of an irregular volcanic source, we devise a new sparsity‐promoting modeling scheme assuming active magma bodies are well‐localized melt accumulations, namely, outliers in the background crust. First, surface deformation data are inverted using a hybridL1‐ andL2‐norm regularization scheme to solve for sparse volume change distributions. Next, a boundary element method is implemented to solve for the displacement discontinuity distribution of the reservoir, which satisfies a uniform pressure boundary condition. The inversion approach is thoroughly validated using benchmark and synthetic tests, of which the results show that source dimension, depth, and shape can be recovered appropriately. We apply this modeling scheme to deformation observed at Kilauea summit for periods of uplift and subsidence leading to and following the 2007 Father's Day event. We find that the magmatic source geometries for these periods are statistically distinct, which may be an indicator that magma is released from isolated compartments due to large differential pressure leading to the rift intrusion.
Evaluation of the Runoff and River Routing Schemes in the Community Land Model of the Yellow River Basin
Authors: Sheng Mingyang , Lei Huimin , Jiao Yang , Yang Dawen 
Published: December 2017

AbstractRunoff and river routing schemes play important roles in land surface models (LSMs) because they regulate the soil moisture, heat flux, and vegetation dynamics of land surface processes and account for the carbon and nutrient transport in river channels. However, these schemes are often simplistic and conceptual. Hence, in this study, we focused on (1) evaluating these schemes in the Community Land Model (CLM) and (2) altering the model representations using physically based schemes based on a study of the Yellow River basin. For runoff simulation, CLM exhibits limitations in water‐limited areas, especially areas with aridity index values greater than 2. Additionally, CLM greatly overestimates runoff, and produces negative Nash‐Sutcliffe efficiency (NSE) coefficients, few quick flow variations, high quick flow index values, and large root mean square errors of total water storage. These issues were greatly improved by implementing schemes of physically based overland flow, lateral soil water flow, and interchange between groundwater and river water. Furthermore, for the river routing scheme, the use of 1‐D kinematic wave routing improved previously unrealistic aspects of the flood hydrographs (e.g., incorrect flood peak values and times) of the original CLM. Moreover, compared with using the grid element‐based river routing approach in CLM, the computational costs were reduced by up to 45% by implementing the flow interval element method. Finally, our results indicate that parameter calibration in CLM minimally improved the simulation performance in water‐limited areas, while physically based schemes generated better results.
Characterization of Moist Processes Associated With Changes in the Propagation of the MJO With Increasing CO2
Authors: Adames Ángel F. , Kim Daehyun , Sobel Adam H. , Del Genio Anthony , Wu Jingbo 
Published: December 2017

AbstractThe processes that lead to changes in the propagation and maintenance of the Madden‐Julian Oscillation (MJO) as a response to increasing CO2are examined by analyzing moist static energy budget of the MJO in a series of NASA GISS model simulations. It is found changes in MJO propagation is dominated by several key processes. Horizontal moisture advection, a key process for MJO propagation, is found to enhance predominantly due to an increase in the mean horizontal moisture gradients. The terms that determine the strength of the advecting wind anomalies, the MJO horizontal scale and the dry static stability, are found to exhibit opposing trends that largely cancel out. Furthermore, reduced sensitivity of precipitation to changes in column moisture, i.e., a lengthening in the convective moisture adjustment time scale, also opposes enhanced propagation. The dispersion relationship of Adames and Kim, which accounts for all these processes, predicts an acceleration of the MJO at a rate of ∼3.5% K−1, which is consistent with the actual phase speed changes in the simulation. For the processes that contribute to MJO maintenance, it is found that damping by vertical MSE advection is reduced due to the increasing vertical moisture gradient. This weaker damping is nearly canceled by weaker maintenance by cloud‐radiative feedbacks, yielding the growth rate from the linear moisture mode theory nearly unchanged with the warming. Furthermore, the estimated growth rates are found to be a small, negative values, suggesting that the MJO in the simulation is a weakly damped mode.
Comparison of a new nanoform of the photosensitizer chlorin e6, based on plant phospholipids, with its free form
Authors: Kostryukova Lyubov V. , Prozorovskiy Vladimir N. , Medvedeva Natalya V. , Ipatova Olga M. 
Published: December 2017

Photodynamic therapy is an advanced method of treating cancer and various benign diseases, including infections. It uses light‐activated molecules [photosensitizers (PSs)] to generate reactive oxygen species (ROS) when irradiated with light of a specific wavelength. This study examined the photophysical and photosensitizing activity of the PS chlorin e6 incorporated in a delivery system based on plant phospholipids. This new nanoform of chlorin e6 comprised particles with a diameter of 18.4 ± 2.5 nm and zeta potential of −34.6 ± 3.0 mV. Incorporation of chlorin e6 in phospholipid nanoparticles was observed to cause a bathochromic shift of Q‐band absorption maximum by 14 nm without an absorption change in the range of the Soret band. Fluorescence intensity of chlorin e6 embedded in the phospholipid nanoparticles increased 1.7‐fold. Chlorin e6 in phospholipid nanoparticles, when irradiated, was able to generate ROS as shown by oxidation of polyunsaturated fatty acids of the phospholipid matrix of the delivery system and reduced l‐glutathione. In vivo it was demonstrated that the new nanoform of chlorin e6 provides more accumulation of PSs in tumor tissue than its free form. Moreover, its accumulation in the skin was lower and its elimination from the skin almost five times faster than when administered in free form. The observed differences of this new nanoform of chlorin e6 should lead to enhancement of antitumor efficacy and a decrease in phototoxicity.
Synaptic Suppression Triplet‐STDP Learning Rule Realized in Second‐Order Memristors
Authors: Yang Rui , Huang He‐Ming , Hong Qing‐Hui , Yin Xue‐Bing , Tan Zheng‐Hua , Shi Tuo , Zhou Ya‐Xiong , Miao Xiang‐Shui , Wang Xiao‐Ping , Mi Shao‐Bo , Jia Chun‐Lin , Guo Xin 
Published: December 2017

AbstractThe synaptic weight modification depends not only on interval of the pre‐/postspike pairs according to spike‐timing dependent plasticity (classical pair‐STDP), but also on the timing of the preceding spike (triplet‐STDP). Triplet‐STDP reflects the unavoidable interaction of spike pairs in natural spike trains through the short‐term suppression effect of preceding spikes. Second‐order memristors with one state variable possessing short‐term dynamics work in a way similar to the biological system. In this work, the suppression triplet‐STDP learning rule is faithfully demonstrated by experiments and simulations using second‐order memristors. Furthermore, a leaky‐integrate‐and‐fire (LIF) neuron is simulated using a circuit constructed with second‐order memristors. Taking the advantage of the LIF neuron, various neuromimetic dynamic processes, including local graded potential leaking out, postsynaptic impulse generation and backpropagation, and synaptic weight modification according to the suppression triplet‐STDP rule, are realized. The realized weight‐dependent pair‐ and triplet‐STDP rules are clearly in line with findings in biology. The physically realized triplet‐STDP rule is powerful in developing direction and speed selectivity for complex pattern recognition and tracking tasks. These scalable artificial synapses and neurons realized in second‐order memristors can intrinsically capture the neuromimetic dynamic processes; they are the promising building blocks for constructing brain‐inspired computation systems.
Electrochemically Inert g‐C3N4 Promotes Water Oxidation Catalysis
Authors: Chen Yaping , Zhou Qian , Zhao Guoqiang , Yu Zhenwei , Wang Xiaolin , Dou Shi Xue , Sun Wenping 
Published: December 2017

AbstractElectrode surface wettability is critically important for heterogeneous electrochemical reactions taking place in aqueous and nonaqueous media. Herein, electrochemically inert g‐C3N4 (GCN) is successfully demonstrated to significantly enhance water oxidation by constructing a superhydrophilic catalyst surface and promoting substantial exposure of active sites. As a proof‐of‐concept application, superhydrophilic GCN/Ni(OH)2 (GCNN) hybrids with monodispersed Ni(OH)2 nanoplates strongly anchored on GCN are synthesized for enhanced water oxidation catalysis. Owing to the superhydrophilicity of functionalized GCN, the surface wettability of GCNN (contact angle 0°) is substantially improved as compared with bare Ni(OH)2 (contact angle 21°). Besides, GCN nanosheets can effectively suppress Ni(OH)2 aggregation to help expose more active sites. Benefiting from the well‐defined catalyst surface, the optimal GCNN hybrid shows significantly enhanced electrochemical performance over bare Ni(OH)2 nanosheets, although GCN is electrochemically inert. In addition, similar catalytic performance promotion resulting from wettability improvement induced by incorporation of hydrophilic GCN is also successfully demonstrated on Co(OH)2. The present results demonstrate that, in addition to developing new catalysts, building efficient surface chemistry is also vital to achieve extraordinary water oxidation performance.
Tuning Electrical Properties of 2D Materials by Self‐Assembled Monolayers
Authors: Lee Wi Hyoung , Park Yeong Don 
Published: December 2017

AbstractTuning of electrical properties of 2D materials by self‐assembled monolayers (SAMs) is reviewed in this article. When 2D materials such as graphene and transition metal dichalcogenides (TMDs) are in contact with SAMs, end functional group in SAMs governs dipole moment in SAMs, thereby affecting shift of Fermi level for instantaneous doping of 2D materials. Accordingly, carrier density, work function, and/or field‐effect mobility of 2D materials are changed by the SAMs contact. Recent advances in the SAMs‐induced changes of electrical properties in 2D materials are introduced by considering two types of 2D materials‐SAMs contacts: 1) 2D materials on SAMs and 2) SAMs on 2D materials. 2D materials from graphene to TMDs are fully discussed in the context of SAMs‐induced doping.
Detecting and Tuning the Interactions between Surfactants and Carbon Nanotubes for Their High‐Efficiency Structure Separation
Authors: Zeng Xiang , Yang Dehua , Liu Huaping , Zhou Naigen , Wang Yanchun , Zhou Weiya , Xie Sishen , Kataura Hiromichi 
Published: December 2017

AbstractThe selective interaction is systematically explored between the surfactants (sodium deoxycholate (DOC), sodium dodecyl sulfate (SDS), and sodium cholate (SC)) and the single‐wall carbon nanotubes (SWCNTs) by the gel chromatography technique. The results show that DOC preferentially interacts with small‐diameter semiconducting SWCNTs (S‐SWCNTs), exhibiting the strongest interaction strength for the SWCNTs, and the highest structural selectivity. The surfactant SC shows high selectivity toward the chiral angles of the SWCNTs. Its interaction strength and structural recognition ability are slightly higher than that of SDS but lower than that of DOC. Combining with the proved selectivity of SDS in the adsorption onto the S‐SWCNTs with small CC bond curvature, it is discovered that the synergistic effect of the triple surfactants amplified the interaction difference among the different SWCNTs and the gel, and thus dramatically improved the separation efficiency and structural purity of the SWCNTs, achieving the separation of distinct (n, m) single‐chirality species and their enantiomers in one step. This work not only provides deeper insights into the separation mechanism of SWCNTs with the surfactant sorting techniques, but also has a profound significance in studying the interaction between the SWCNTs and other small molecules.
A Novel Multiple Interface Structure with the Segregation of Dopants in Lead‐Free Ferroelectric (K0.5Na0.5)NbO3 Thin Films
Authors: Li Chao , Wang Lingyan , Chen Wen , Lu Lu , Nan Hu , Wang Dawei , Zhang Yijun , Yang Yaodong , Jia Chun‐Lin 
Published: December 2017

AbstractInterfaces in oxides are found to possess different properties and can be engineered for modifying local structure and properties of nearby area. In this work, it is reported that the interfaces can be formed in Ba/Zr (BZ)‐doped (K,Na)NbO3 (KNN) thin films by cycles of chemical solution deposition using same precursor solution. In the films, a novel and special cross‐sectional structure is observed with periodic distribution of Ba‐rich and Zr‐rich layers. The Ba‐rich and Zr‐rich layers exhibit different strain, lattice parameters, and crystal structure, leading to an obvious effect on the general ferroelectric properties of the KNN‐based thin films. Moreover, the self‐polarization is also observed, which can be understood to originate from the formed built‐in field by layered distribution of Ba and Zr in the KNN‐BZ thin films.
Flexible WS2@CNFs Membrane Electrode with Outstanding Lithium Storage Performance Derived from Capacitive Behavior
Authors: Wu Chen , Zeng Xiaohui , He Pingge , Chen Libao , Wei Weifeng 
Published: December 2017

AbstractFlexible electrodes have recently elicited attention due to their potential to be woven into textiles as flexible power supplies for wearable electronic devices. However, contemporary flexible electrodes generally suffer from the limited reaction kinetics and inferior stability. Here, a flexible WS2@CNFs membrane electrode is facilely fabricated via hydrothermal method and subsequent electrospinning to embed WS2 nanosheets into interconnected framework of carbon nanofibers (CNFs). Benefitting from 3D porous architecture and good conductivity of CNFs, WS2@CNFs composites exhibit outstanding cycling stability and rate capability as self‐supported binder‐free anode for lithium‐ion batteries. Especially, WS2@CNFs with 60.3 wt% of WS2 displays a discharge specific capacity as high as 545 mA h g−1 at 0.5 A g−1 after 800 cycles. Even at 2 A g−1, it maintains 62.4% of specific capacity at 0.1 A g−1, and stably cycles back at 0.1 A g−1. Kinetic analysis confirms that the capacitive mechanism is dominant in the Li‐ion storage process, which is derived mainly from the structure evolution from WS2 nanosheets to WS2/W nanoparticles during extended cycling. The reduced nanoparticles also enhance electrochemical activity, conductivity, and reversibility of the conversion reaction, resulting in the increasing capacity with cycles.