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Aims. This paper aims to track the three-dimensional (3D) evolution of a full halo coronal mass ejection (CME) on 2011 June 21. Methods. The CME results from a nonradial eruption of a filament-carrying flux rope in NOAA active region 11236. The eruption was observed in extreme-ultraviolet (EUV) wavelengths by the extreme-ultraviolet imager (EUVI) on board the ahead and behind Solar TErrestrial RElations Observatory (STEREO) spacecrafts and the atmospheric imaging assembly (AIA) on board the solar dynamics observatory (SDO). The CME was observed by the COR1 coronagraph on board STEREO and the C2 coronagraph on board the large angle spectroscopic coronagraph (LASCO). The revised cone model was slightly modified, with the top of the cone becoming a sphere, which is internally tangent to the legs. Using the multipoint observations, the cone model was applied to derive the morphological and kinematic properties of the CME. Results. The cone shape fits nicely with the CME observed by EUVI and COR1 on board the STEREO twin spacecraft and LASCO/C2 coronagraph. The cone angle increases sharply from 54° to 130° in the initial phase, indicating a rapid expansion. A relation between the cone angle and the heliocentric distance of the CME leading front is derived, ω = 130° −480d−5, where d is in units of R⊙. The inclination angle decreases gradually from ∼51° to ∼18°, suggesting a trend of radial propagation. The heliocentric distance increases gradually in the initial phase and quickly in the later phase up to ∼11 R⊙. The true speed of the CME reaches ∼1140 km s−1, which is ∼1.6 times higher than the apparent speed in the LASCO/C2 field of view. Conclusions. The revised cone model is promising in tracking the complete evolution of CMEs. [ABSTRACT FROM AUTHOR]

We investigate the transverse coronal-loop oscillations induced by the eruption of a prominence-carrying flux rope on 7 December 2012. The flux rope, originating from NOAA Active Region (AR) 11621, was observed in extreme-ultraviolet (EUV) wavelengths by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) spacecraft and in the H α line center by the ground-based telescope at the Big Bear Solar Observatory (BBSO). The early evolution of the flux rope is divided into two steps: a slow-rise phase at a speed of ≈ 230 km s−1 and a fast-rise phase at a speed of ≈ 706 km s−1. The eruption generates a C5.8 flare and the onset of the fast rise is consistent with the hard X-ray (HXR) peak time of the flare. The embedded prominence has a lower speed of ≈ 452 km s−1. The eruption is significantly inclined from the local solar normal by ≈ 60∘, suggesting a typical non-radial eruption. During the early eruption of the flux rope, the nearby coronal loops are disturbed and experience independent kink-mode oscillations in the horizontal and vertical directions. The oscillation in the horizontal direction has an initial amplitude of ≈ 3.1 Mm, a period of ≈ 294 seconds, and a damping time of ≈ 645 seconds. It is most striking in 171 Å and lasts for three to four cycles. The oscillations in the vertical directions are observed mainly in 171, 193, and 211 Å. The initial amplitudes are in the range of 3.4 – 5.2 Mm, with an average value of 4.5 Mm. The periods are between 407 seconds and 441 seconds, with an average value of 423 seconds. The oscillations are damping and last for nearly four cycles. The damping times are in the range of 570 – 1012 seconds, with an average value of 741 seconds. Assuming a semi-circular shape of the vertically oscillating loops, we calculate the loop lengths according to their heights. Using the observed periods, we carry out coronal seismology and estimate the internal Alfvén speeds (988 – 1145 km s−1) and the magnetic-field strengths (12 – 43 G) of the oscillating loops. [ABSTRACT FROM AUTHOR]

Context. The traditional cone models achieve great success in studying the geometrical and kinematic properties of halo coronal mass ejections (CMEs). Aims. In this Letter, a revised cone model is proposed to investigate the properties of CMEs as a result of non-radial prominence eruptions. Methods. The cone apex is located at the source region of an eruption instead of the Sun center. The cone axis deviates from the local vertical by an inclination angle of θ1 and an angle of ϕ1. The length and angular width of the cone are r and ω, respectively. Results. The model was successfully applied to two CMEs originating from the western limb on 2011 August 11 and 2012 December 7. By comparing the projections of the cones with the CME fronts simultaneously observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Extreme-Ultraviolet Imager on board the ahead Solar TErrestrial RElations Observatory, the properties of the CMEs were derived, including the distance, angular width, inclination angle, deviation from the plane of the sky, and true speed in space. Conclusions. This revised cone model provides a new and complementary approach in exploring the whole evolutions of CMEs. [ABSTRACT FROM AUTHOR]

In this study, we investigate the energy partition of four confined circular-ribbon flares (CRFs) that occurred close to solar disk center. The flares are observed simultaneously by the Solar Dynamics Observatory (SDO), the Geostationary Operational Environmental Satellites (GOES), and the Ramaty Hight Energy Solar Spectroscopic Imager (RHESSI). We calculate different energy components, including the radiative outputs in the ranges 1 – 8 Å, 1 – 70 Å, and 70 – 370 Å, total radiative loss, peak thermal energy derived from GOES and RHESSI, nonthermal energy in flare-accelerated electrons, and magnetic free energy before the flares. It is found that the values of energy components increase systematically with the flare class, indicating that more energy is involved in larger flares. The magnetic free energies ( E m a g ) are larger than the nonthermal energies ( E n t h ) and radiative outputs, which is consistent with the magnetic nature of flares. The ratio E n t h E m a g of the four flares, being 0.70 – 0.76, is considerably higher than that of eruptive flares. Hence, this ratio may serve as an important factor for discriminating confined from eruptive flares. The nonthermal energies are sufficient to provide the heating requirements including the peak thermal energy and radiative loss. Our findings impose constraints on theoretical models of confined CRFs and have potential implications on space weather forecast. [ABSTRACT FROM AUTHOR]

Aims. The aim of this study is to investigate the excitation of kink oscillations in coronal loops and filaments, by analyzing a C3.4 circular-ribbon flare associated with a blowout jet in active region 12434 on 2015 October 16. Methods. The flare was observed in ultraviolet and extreme-ultraviolet wavelengths by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) spacecraft. The line-of-sight (LOS) magnetograms of the photosphere were observed by the Helioseismic and Magnetic Imager on board SDO. Soft X-ray fluxes of the flares in 0.5−4 and 1−8 Å were recorded by the GOES spacecraft. Results. The flare excited small-amplitude kink oscillation of a remote coronal loop. The oscillation lasted for ≥4 cycles without significant damping. The amplitude and period are 0.3 ± 0.1 Mm and 207 ± 12 s. Interestingly, the flare also excited transverse oscillation of a remote filament. The oscillation lasted for ∼3.5 cycles with decaying amplitudes. The initial amplitude is 1.7−2.2 Mm. The period and damping time are 437−475 s and 1142−1600 s. The starting times of simultaneous oscillations of coronal loop and filament were concurrent with the hard X-ray peak time. Though small in size and short in lifetime, the flare set off a chain reaction. It generated a bright secondary flare ribbon (SFR) in the chromosphere, remote brightening (RB) that was cospatial with the filament, and intermittent, jet-like flow propagating in the northeast direction. Conclusions. The loop oscillation is most probably excited by the flare-induced blast wave at a speed of ≥1300 km s−1. The excitation of the filament oscillation is more complicated. The blast wave triggers secondary magnetic reconnection far from the main flare, which not only heats the local plasma to higher temperatures (SFR and RB), but produces jet-like flow (i.e., reconnection outflow) as well. The filament is disturbed by the secondary magnetic reconnection and experiences transverse oscillation. These findings provide new insight into the excitation of transverse oscillations of coronal loops and filaments. [ABSTRACT FROM AUTHOR]

Solar radio spikes are short-duration, narrow-band burst signals, which are a fine structure of solar radio bursts. The processing and analysis of their observed data are of great significance in the study of electron acceleration in the process of solar flares and electron acceleration during the explosion and diagnosis of corona parameters. Deep learning interprets data by mimicking the mechanism of the human brain. Faster Region-based Convolutional Neural Network (Faster R-CNN) is a branch of deep learning based on region nomination, and its classification results have considerable advantages in accuracy. In this paper, Faster R-CNN will be used to identify and extract solar radio spikes. In order to improve the detection ability of small events, a multi-scale detection frame and a multi-layer feature fusion training method are used. The analysis results show that the Average Precision (AP) value of the improved network is close to 91%, which is nearly 10% higher than the original network. So the improved Faster R-CNN method can also be used for the identification and extraction of small-scale fine structures in other fields. [ABSTRACT FROM AUTHOR]

Context. Large-amplitude, longitudinal filament oscillations triggered by solar flares have been well established in the literature. However, filament oscillations enhanced by flares have never been reported. Aims. In this paper we report the multiwavelength observations of a very long filament in active region (AR) 11112 on 2010 October 18. The filament was composed of two parts, the eastern part (EP) and the western part (WP). We focus on longitudinal oscillations of the EP, which were enhanced by two homologous C-class flares in the same AR. Methods. The filament was observed in Hff wavelength by the Global Oscillation Network Group and in extreme ultraviolet wavelengths by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO). Line-of-sight magnetograms were provided by the Helioseismic and Magnetic Imager on board SDO. The global three-dimensional magnetic fields were obtained using the potential field source surface modeling. Soft X-ray light curves of the two flares were recorded by the GOES spacecraft. White light images of the corona were observed by the LASCO/C2 coronagraph on board SOHO. To reproduce part of the observations, we perform one-dimensional, hydrodynamic numerical simulations using the MPI-AMRVAC code. Results. The C1.3 flare was confined without a coronal mass ejection (CME). Both EP and WP of the filament were slightly disturbed and survived the flare. After 5 h, eruption of the WP generated a C2.6 flare and a narrow jet-like CME. Three oscillating threads (thda, thdb, thdc) are obviously identified in the EP, and their oscillations are naturally divided into three phases by the two flares. The initial amplitude ranges from 1.6 to 30Mm with a mean value of ~14 Mm. The period ranges from 34 to 73 min with a mean value of ~53 min. The curvature radii of the magnetic dips are estimated to be 29 to 133Mm with a mean value of ~74 Mm. The damping times ranges from ~62 to ~96 min with a mean value of ~82 min. The value of =P is between 1.2 and 1.8. For thda in the EP, the amplitudes were enhanced by the two flares from 6.1Mm to 6.8Mm after the C1.3 flare, and further to 21.4Mm after the C2.6 flare. The period variation as a result of perturbation from the flares was within 20%. The attenuation became faster after the C2.6 flare. Conclusions. To the best of our knowledge, this is the first report of large-amplitude, longitudinal filament oscillations enhanced by flares. Numerical simulations reproduce the oscillations of thda very well. The simulated amplitudes and periods are close to the observed values, while the damping time in the last phase is longer, implying additional mechanisms should be taken into account apart from radiative loss. [ABSTRACT FROM AUTHOR]

The dielectric behavior of the high-energy electron irradiated poly(vinylidene fluoridetrifluoroethylene) 68/32 mol % copolymer was characterized in the dose range from 0 to 175 Mrad. It was found that as the dose increases, the copolymer evolves from a normal ferroelectric to a relaxor ferroelectric and then to a simple relaxor. Correspondingly, the crystalline morphology changes from a two-phase coexistence between a polar and nonpolar phases at low doses (<50 Mrad) to a macroscopically uniform nonpolar phase for doses beyond 50 Mrad, as revealed by x-ray data. Interestingly, it was observed that in the whole dose range, the Vogel-Fulcher (V-F) relationship could describe the measured relationship between the frequency and the peak temperature of dielectric constant well. For the copolymers irradiated with dose near 75 Mrad, which show a typical relaxor ferroelectric response, the V-F behavior is a result of freezing of the relaxation time (into polar glass state). For the copolymers irradiated with doses lower that 50 Mrad where a polar phase and nonpolar phase coexist, the dielectric data at near the ferroelectric-paraelectric temperature show a dielectric peak with V-F type relaxation followed by a transition from a relaxor ferroelectric and normal ferroelectric as the temperature is lowered, suggesting a possible freezing process even in this dose range. [ABSTRACT FROM AUTHOR]

We report on the observation of the critical thickness of crystallization of ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer thin films, which were solution spun cast on platinum coated silicon wafer. The effect occurs at about 100 nm thickness, which is significantly above any currently known spatial dimensions of the polymer, so that for films at thickness below about 100 nm, the crystallization process is strongly hindered, resulting in a low crystallinity in these films. This low crystallinity leads to a large and discontinuous change of the dielectric constant and ferroelectric polarization in the films below the critical thickness. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated the ultrasonic performance of 1-3 piezocomposites. Sample preparation; Wave propagation in an unbounded 1-3 piezocomposite; Losses in 1-3 piezocomposites.

Presents information on the evaluation of the piezoelectric shear strain S5 of several commerical lead zirconate titanate (PZT) piezoceramics. Findings on both the piezoelectric and dielectric coefficients of PZT; Details on the experiment; Results of experiment.

Deals with a study which investigated the aging characteristics of the electrostrictive lead magnesium niobate-lead titanate [(1-x)PMN-xPT] under direct current bias field. Background to the study; Experimental details; Results and discussions.

Presents a study which examined the electromechanical and dielectric responses of ferroelectric materials near paraelectric-ferroelectric (PF) phase transitions. Results for materials with a first order and second order PF transitions; Equation for the free energy of a PF transition from a cubic to a tetragonal ferroelectric phase; Conclusions.

Presents information on a study which determined the symmetry-predicted nonzero components of the piezoelectric coefficient, dielectric constant and elastic compliance matrices. Preparation of samples; Measurement of the principal diagonal components of the elastic compliance matrix; Frequency dependence of the dielectric constant K[sub33].

Describes the deformation of 1-3 type piezoelectric composite materials under different conditions. Use of piezocomposites; Application of the force equilibrium condition; Comparison between the strain profile of the polymer phase in the 2-2 composite with the 1-3 composite.

Presents a theoretical study on the static performance of piezoelectric ceramic-polymer composites with 1-3 connectivity. Displacement profiles in a single-rod composite under uniaxial and hydrostatic stresses; Aspect ratio of the ceramic rods for 1-3 structures; Calculation of the hydrostatic piezoelectric constant for the single-rod 1-3 composite.

Investigates high-frequency strain response in ferroelectrics using a modified Mach-Zehnder interferometer. Operation principle of laser interferometer; Sample mounting problems; Information on the dispersion of piezoelectric and electrostrictive coefficients of several selected ferroelectrics.

Presents a study that measured the alternating current field dependence of the polarization and strain responses of different compositions of doped lead zirconate titanate ceramics. Analysis of the domain wall excitations in the ceramics; Contributions of the domain wall excitations to the signal response of the ceramics; Examination of the dielectric and piezoelectric coefficients of the ceramics.

Deals with a study of the strain properties of piezoelectric and electrostrictive materials using a modified Michelson interferometer. Detection of small displacement; Piezolectric and electrostrictive measurement; Dual-channel detection and the determination of the strain due to domain switching in ferroelectrics.

We explore quasi-periodic pulsations with multiple periods in hard X-ray (HXR) emission from the Fermi Gamma-ray Burst Monitor during the impulsive phase of a solar flare (SOL2014-09-10). The completely new observational result is that the shorter periods appear at lower energies of the X-ray photons at the beginning and the longer periods appear at higher energies at the end, with some intersection of the periods at medium energies. We also find shorter and then longer periods during the same phase of this flare. Using the wavelet power spectrum and fast Fourier transform spectrum, we analyse the normalized rapidly varying signal divided by its slowly varying signal, which is the smoothed original HXR flux. The periods of 27 and 37 s are derived at lower-energy channels between 17:25 and 17:29 UT (i.e. 12.0-27.3 and 27.3-50.9 keV). Then, the periods of 27, 46 and 60 s are observed at the medium-energy channel from 17:26 to 17:33 UT, such as 50.9-102.3 keV. Also, the period of 80 s is detected at the higher-energy channel from 17:28 to 17:33 UT, such as 102.3-296.4 keV. [ABSTRACT FROM AUTHOR]

Context. Coronal dimmings are regions of decreased extreme-ultravoilet (EUV) and/or X-ray (originally Skylab, then Yohkoh/SXT) intensities, which are often associated with flares and coronal mass ejections (CMEs). The large-scale impulsive dimmings have been thoroughly observed and investigated. The pre-flare dimmings before the flare impulsive phase, however, have rarely been studied in detail. Aims. We focus on the pre-flare coronal dimmings. We report our multiwavelength observations of the GOES X1.6 solar flare and the accompanying halo CME that was produced by the eruption of a sigmoidal magnetic flux rope (MFR) in NOAA active region (AR) 12158 on 2014 September 10. Methods. The eruption was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). The photospheric line-of-sight magnetograms were observed by the Helioseismic and Magnetic Imager (HMI) on board SDO. The soft X-ray (SXR) fluxes were recorded by the GOES spacecraft. The halo CME was observed by the white-light coronagraphs of the Large Angle Spectroscopic Coronagraph (LASCO) on board SOHO. Results. About 96 min before the onset of the flare/CME, narrow pre-flare coronal dimmings appeared at the two ends of the twisted MFR. They extended very slowly, with their intensities decreasing with time, while their apparent widths (8-9 Mm) continued to be nearly constant. During the impulsive and decay phases of flare, typical fan-like twin dimmings appeared and expanded, with a much larger extent and lower intensities than the pre-flare dimmings. The percentage of the 171 Å intensity decrease reaches 40%. The pre-flare dimmings are most striking in 171, 193, and 211 Å with formation temperatures of 0.6-2.5 MK. The northern part of the pre-flare dimmings could also be recognized in 131 and 335 Å. Conclusions. To our knowledge, this is the first detailed study of pre-flare coronal dimmings; they can be explained by density depletion as a result of the gradual expansion of the coronal loop system surrounding the MFR during the slow rise of the MFR. [ABSTRACT FROM AUTHOR]

Analyzes plane wave propagation at the composite-medium interface for the piezoceramic polymer composites with laminated periodic structure. Description of the composite structure; Solution to the field equations in the fluid region in the case of the fluid composite interface; Relationship used to evaluate the input acoustic impedance of a composite at the interface.

Presents a dynamic theory on the piezoceramic polymer composite with 2-2 connectivity. Description and illustration of the composite; Governing equations for the problem using the coordinate system of the composite; Benefits of the theory presented.

Context. Coronal bright points (CBPs) are small-scale and long-duration brightenings in the lower solar corona. They are often explained in terms of magnetic reconnection. Aims. We aim to study the substructures of a CBP and clarify the relationship among the brightenings of different patches inside the CBP. Methods. The event was observed by the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 22-23. Results. The CBP showed repeated brightenings (or CBP flashes). During each of the two successive CBP flashes, that is, weak and strong flashes that were separated by ∼2 hr, the XRT images revealed that the CBP was composed of two chambers, patches A and B. During the weak flash, patch A brightened first, and patch B brightened ∼2 min later. During the transition, the right leg of a large-scale coronal loop drifted from the right side of the CBP to the left side. During the strong flash, patch B brightened first, and patch A brightened ∼ 2 min later. During the transition, the right leg of the large-scale coronal loop drifted from the left side of the CBP to the right side. In each flash, the rapid change of the connectivity of the large-scale coronal loop is strongly suggestive of the interchange reconnection. Conclusions. For the first time we found reciprocatory reconnection in the CBP, which means that reconnected loops in the outflow region of the first reconnection process serve as the inflow of the second reconnection process. [ABSTRACT FROM AUTHOR]

Context. Coronal jets are one type of ubiquitous small-scale activity that is caused by magnetic reconnection in the solar corona. They are often associated with cool surges in the chromosphere. Aims. In this paper, we report our discovery of blobs in the recurrent and homologous jets that occurred at the western edge of the NOAA active region 11259 on 2011 July 22. Methods. The jets were observed in the seven extreme-ultraviolet (EUV) filters of the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory. Using the base-difference images of the six filters (94, 131, 171, 211, 193, and 335 Å), we carried out the differential emission measure (DEM) analyses to explore the thermodynamic evolutions of the jets. The jets were accompanied by cool surges observed in the Hα line center of the ground-based telescope in the Big Bear Solar Observatory. Results. The jets that had lifetimes of 20-30 min recurred at the same place for three times with an interval of 40-45 min. Interestingly, each of the jets intermittently experienced several upward eruptions at the speed of 120-450 km s-1. After reaching the maximum heights, they returned back to the solar surface, showing near-parabolic trajectories. The falling phases were more evident in the low-T filters than in the high-T filters, indicating that the jets experienced cooling after the onset of eruptions. We identified bright and compact blobs in the jets during their rising phases. The simultaneous presence of blobs in all the EUV filters were consistent with the broad ranges of the DEM profiles of the blobs (5.5 ≤ log T ≤ 7.5), indicating their multi-thermal nature. The median temperatures of the blobs were ∼2.3 MK. The blobs that were ∼3 Mm in diameter had lifetimes of 24-60 s. Conclusions. To our knowledge, this is the first report of blobs in coronal jets. We propose that these blobs are plasmoids created by the magnetic reconnection as a result of tearing-mode instability and are ejected out along the jets. [ABSTRACT FROM AUTHOR]

The dilute nanocomposite strategy facilitates a promising route for high-temperature polymer dielectrics to achieve high dielectric constant and energy density, robust breakdown strength, and low loss. The dielectric enhancement of the dilute nanocomposites strongly ties to the topological conditions of the nanofiller–polymer interface. Here, atomic force microscopy-based infrared spectroscopy was employed to observe the interfacial region of a high-temperature poly(arylene ether urea) (PEEU) dilute nanocomposite directly. The experimental results showed that the nanoparticles induce morphological changes in PEEU, and the interface region extends over 150 nm away from the nanofiller surfaces. Such nano-morphology changes are highly indicative of generating a large enhancement of the dielectric performance in the PEEU dilute nanocomposite. [ABSTRACT FROM AUTHOR]

La1-xSrxCoO3 (x=0.18, 0.33, and 0.5) films were grown epitaxially on piezoelectric Pb (Mg1/3Nb2/3)O3- PbTiO3 substrates by pulsed laser deposition. The magnetization of these films varies with the external electric field, showing the magnetoelectric effect. With different doping content of Sr2+ ions, the change of magnetization for these films show different behaviors with increasing temperature, which can be attributed to the competition between electric-field-induced changes of spin state and double exchange interaction. This work presents an alternative mechanism to investigate the electric field control of magnetism in magnetoelectric heterostructure by tuning the spin state. [ABSTRACT FROM AUTHOR]

Aims. We report our observations of a swirling flare-related extreme-ultraviolet (EUV) jet on 2011 October 15 at the edge of NOAA active region 11314. Methods. We used the multiwavelength observations in the EUV passbands from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). We extracted a wide slit along the jet axis and 12 thin slits across its axis to investigate the longitudinal motion and transverse rotation. We also used data from the Extreme-Ultraviolet Imager (EUVI) aboard the Solar TErrestrial RElations Observatory (STEREO) spacecraft to investigate the three-dimensional (3D) structure of the jet. Ground-based Ha images from the El Teide Observatory, a member of the Global Oscillation Network Group (GONG), provide a good opportunity to explore the relationship between the cool surge and the hot jet. Line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) aboard SDO enable us to study the magnetic evolution of the flare/jet event. We carried out potential-field extrapolation to calculate the magnetic configuration associated with the jet. Results. The onset of jet eruption coincided with the start time of the C1.6 flare impulsive phase. The initial velocity and acceleration of the longitudinal motion were 254 ± 10 km s-1 and -97 ± 5 m s-2, respectively. The jet presented helical structure and transverse swirling motion at the beginning of its eruption. The counter-clockwise rotation slowed down from an average velocity of ~122 km s-1 to ~80 km s-1. The interwinding thick threads of the jet untwisted into multiple thin threads during the rotation that lasted for one cycle with a period of ~7 min and an amplitude that increases from ~3.2 Mm at the bottom to ~11 Mm at the upper part. Afterwards, the curtain-like leading edge of the jet continued rising without rotation, leaving a dimming region behind, before falling back to the solar surface. The appearance/disappearance of dimming corresponded to the longitudinal ascending/descending motions of jet. Cospatial Ha surge and EUV dimming imply that the dimming resulted from the absorption of hot EUV emission by the cool surge. The flare/jet event was caused by continuous magnetic cancellation before the start of the flare. The jet was associated with the open magnetic fields at the edge of AR 11314. [ABSTRACT FROM AUTHOR]

We demonstrate an obvious electric-field control of magnetic properties in CoPt/PMN-PT heterostructure at room temperature. Not only the remanent magnetization but also the coercivity exhibits an obvious response with the electric field. Without the aid of magnetic bias field, the remanent magnetization of the CoPt film shows an analogous on-off behavior with the electric field switching on and off alternatively. The magnetization reversal can be electrically controlled in this heterostructure due to the variation of coercivity caused by electric field. [ABSTRACT FROM AUTHOR]

Magnetoconductance response (MC) in illuminated tris-(8-hydroxyquinolinato) aluminum (Alq3) single layer has been studied to clarify the role of excitons and electron-hole (e-h) pairs on the MC generation. By fitting the MC curves at different bias conditions, the contribution of e-h pairs and excitons to the MC can be differentiated in the same material. The fitting results indicated that hyperfine mixing between the singlet and triplet e-h pairs results in a Lorentzian type MC within hyperfine field and charge reaction of triplet excitons induces a high-field MC following a non-Lorentzian shape, respectively. Moreover, the characteristic field width for the high-field MC is very different at forward and reverse bias regime, implying that the rate strength for the hole/electron-exciton reactions in Alq3 should be treated separately. [ABSTRACT FROM AUTHOR]

Iron-based superconducting layered compounds have the second highest transition temperature after cuprate superconductors. Their discovery is a milestone in the history of high-temperature superconductivity and will have profound implications for high-temperature superconducting mechanism as well as industrial applications. Raman scattering has been extensively applied to correlated electron systems including the new superconductors due to its unique ability to probe multiple primary excitations and their coupling. In this review, we will give a brief summary of the existing Raman experiments in the iron-based materials and their implications for pairing mechanism in particular. And we will also address some open issues from the experiments. [ABSTRACT FROM AUTHOR]

Context. Filament longitudinal oscillations have been observed in Ha observations of the solar disk. Aims. We intend to find an example of the longitudinal oscillations of a prominence, where the magnetic dip can be seen directly, and examine the restoring force of this type of oscillations. Methods. We carry out a multiwavelength data analysis of the active region prominence oscillations above the western limb on 2007 February 8. In addition, we perform a one-dimensional hydrodynamic simulation of the longitudinal oscillations. Results. Our analysis of high-resolution observations performed by Hinode/SOT indicate that the prominence, seen as a concave-inward shape in lower-resolution extreme ultraviolet (EUV) images, consists of many concave-outward threads, which is indicative of magnetic dips. After being injected into the dip region, a bulk of prominence material started to oscillate for more than 3.5 h, with the period of 52 min. The oscillation decayed with time, on the decay timescale 133 min. Our hydrodynamic simulation can reproduce the oscillation period, but the damping timescale in the simulation is 1.5 times as long as the observations. Conclusions. The results clearly show the prominence longitudinal oscillations around the dip of the prominence and our study suggests that the restoring force of the longitudinal oscillations might be the gravity. Radiation and heat conduction are insufficient to explain the decay of the oscillations. Other mechanisms, such as wave leakage and mass accretion, have to be considered. The possible relation between the longitudinal oscillations and the later eruption of a prominence thread, as well as a coronal mass ejection (CME), is also discussed. [ABSTRACT FROM AUTHOR]

Coronal bright points (CBPs) are long-lived small-scale brightenings in the solar corona. They are generally explained by magnetic reconnection. However, the corresponding magnetic configurations are not well understood. We carry out a detailed multi-wavelength analysis of two neighboring CBPs on 2007 March 16, observed in soft X-ray (SXR) and EUV channels. It is seen that the SXR light curves present quasi-periodic flashes with an interval of ~1 hr superposed over the long-lived mild brightenings, suggesting that the SXR brightenings of this type of CBPs might consist of two components: one is the gentle brightenings and the other is the CBP flashes. It is found that the strong flashes of the bigger CBP are always accompanied by SXR jets. The potential field extrapolation indicates that both CBPs are covered by a dome-like separatrix surface, with a magnetic null point above. We propose that the repetitive CBP flashes, as well as the recurrent SXR jets, result from the impulsive null-point reconnection, while the long-lived brightenings are due to the interchange reconnection along the separatrix surface. Although the EUV images at high-temperature lines resemble the SXR appearance, the 171 Å and 195 Å channels reveal that the blurry CBP in SXR consists of a cusp-shaped loop and several separate bright patches, which are explained to be due to the null-point reconnection and the separatrix reconnection, respectively. [ABSTRACT FROM AUTHOR]

A nickel based superalloy honeycomb sandwich was manufactured by high temperature brazing. The microstructure evolution and the out of plate mechanical properties were investigated for honeycomb sandwiches aged at 1000°C in the present paper. The maximum tensile stress was 28.5 MPa and the compressive yield strength was 29.6 MPa for the original specimens. These parameters decreased to 22.9 and 20.5 MPa for specimens aged for 2 h, to 18.2 and 12.2 MPa for specimens aged for 5 h and to 20.2 and 14.3 MPa for specimens aged for 10 h respectively. With increasing aging time the tensile elongation decreased, the intermetallic compounds and the eutectic structure in the brazing region disappeared, and the solid solution approaching the matrix gradually increased. [ABSTRACT FROM AUTHOR]

Purpose: It is of interest to perform a systematic comparative analysis of the conserved domains in DNA glycosylases and the evolution of DNA base excision repair systems. Furthermore, it is important to characterize the roles and regulation of base excision repair during the development of organisms. To address these issues, we first identified 8-oxo-7,8-dihydroguanine (8-oxoG)-DNA glycosylase (Ogg1) of the ascidian Ciona intestinalis as a good model system. Materials and methods: A cDNA clone coding for a peptide with homology to human Ogg1 was identified in the expressed sequence tag (EST) database from the Ciona cDNA resources. We examined whether CiOgg1 has DNA glycosylase/AP (apurinic/apyrimidinic) lyase activities for 8-oxoG-containing oligonucleotide. Furthermore, the expression level of CiOgg1 was compared in various tissues of Ciona intestinalis . Results: The CiOgg1 gene encoded a protein of 351 amino acids, which shows 37% identity of amino acid sequence with human Ogg1. The Helix-hairpin-Helix motif was highly conserved. The ascidian enzyme had functional 8-oxoG-DNA glycosylase/AP lyase activities, which removed 8-oxoG opposite cytosine from DNA. Expression of the CiOgg1 significantly reduced the frequency of spontaneous G:C to T:A transversions in E. coli mutM mutY . The highest expression level was observed in testis in Ciona intestinalis . Conclusions: The structure and functions of Ogg1 are well conserved in Ciona intestinalis . CiOgg1 is involved in the repair of 8-oxoG in DNA in Ciona intestinalis . [ABSTRACT FROM AUTHOR]

Purpose : In order to clarify the cellular processing and repair mechanisms for radiation-induced clustered DNA damage, we examined the correlation between the levels of DNA glycosylases and the sensitivity to ionizing radiation in Escherichia coli . Materials and methods : The lethal effects of ?-rays, X-rays, a-particles and H2O2 were determined in E. coli with different levels of DNA glycosylases. The formation of double-strand breaks by post-irradiation treatment with DNA glycosylase was assayed with ?-irradiated plasmid DNA in vitro . Results : An E. coli mutM nth nei triple mutant was less sensitive to the lethal effect of sparsely ionizing radiation (?-rays and X-rays) than the wild-type strain. Overproduction of MutM (8-oxoguanine-DNA glycosylase), Nth (endonuclease III) and Nei (endonulease VIII) increased the sensitivity to ?-rays, whereas it did not affect the sensitivity to a-particles. Increased sensitivity to ?-rays also occurred in E. coli overproducing human 8-oxoguanine-DNA glycosylase (hOgg1). Treatment of ?-irradiated plasmid DNA with purified MutM converted the covalently closed circular to the linear form of the DNA. On the other hand, overproduction of MutM conferred resistance to H2O2 on the E. coli mutM nth nei mutant. Conclusions : The levels of DNA glycosylases affect the sensitivity of E. coli to ?-rays and X-rays. Excessive excision by DNA glycosylases converts nearly opposite base damage in clustered DNA damage to double-strand breaks, which are potentially lethal. [ABSTRACT FROM AUTHOR]

Purpose: Although strong static magnetic fields (SMF) are supposed to have the potential to affect biological systems, the effects have not been evaluated sufficiently. Experiments should be performed with a powerful SMF-generating apparatus to evaluate the biological effects of SMF. Materials and methods: An Escherichia coli mutation assay was used to assess the mutagenic effects of strong SMF. Various mutant strains of E. coli were exposed to up to 9 Tesla (T) for 24 h and the frequencies of rifampicin-resistant mutations were then determined. The expression of the soxS::lacZ fusion gene was assessed by measurement of β-galactosidase activity. Results: The results for survival or mutation were obtained with wild-type E. coli strain GC4468 and its derivatives defective in DNA repair enzymes or redox-regulating enzymes were all negative. On the other hand, the mutation frequency was significantly increased by the SMF exposure in soxR and sodAsodB mutants, which are defective in defence mechanisms against oxidative stress. Furthermore, the expression of superoxideinducible soxS::lacZ fusion gene was stimulated 1.4- and 1.8-fold in E. coli when exposed to 5 and 9 T, respectively. Conclusions: These results indicate that strong SMF induce mutations through elevated production of intracellular superoxide radicals in E. coli. [ABSTRACT FROM AUTHOR]

Purpose: 2-Hydroxyadenine (2-ohA) is an oxidation product of adenine generated in DNA by ionizing radiation and various chemical oxidants. 2-ohA has mutational potential comparable to that of 8-oxoguanine in bacteria and mammalian cells. Recent studies have shown that 2-ohA is removed from DNA by a human MutY homolog, MYH protein, in vitro. On the other hand, the repair mechanisms for 2-ohA in Escherichia coli are not yet understood. Materials and methods: Gel shift assays were used to assess the binding activity of E. coli full-length MutY protein and its N-terminal (residues 1-226) domain (M25) to 2-ohA/G-, 2-ohA/A-, 2-ohA/C- and 2-ohA/T-containing 24-mer oligonucleotides. Furthermore, whether these proteins specifically cleave 2-ohA-containing duplex oligonucleotides was examined. Results: The purified MutY and M25 proteins had similar binding affinities to 2-ohA/G-, 2-ohA/A- and 2-ohA/C-containing oligonucleotides. MutY protein removed 2-ohA preferentially from 2-ohA/G mispairs. M25 protein showed the reduced catalytic activity for 2-ohA/G-containing oligonucleotides. Conclusions: E. coli MutY protein has a DNA glycosylase activity that removes 2-ohA from 2-ohA/G mispairs in DNA. The C-terminal domain is required for the removal of 2-ohA from DNA, but is not crucial for binding to 2-ohA-containing oligonucleotides. [ABSTRACT FROM AUTHOR]

The adsorption energetics of Ge dimers on the (1 0 0) surfaces of Ge and Si has been investigated using the first-principles molecular dynamics method. Four high-symmetry configurations have been considered and fully relaxed. The most stable configuration for Ge dimers on Si(1 0 0) is found to be in the trough between two surface dimer rows, oriented parallel to the substrate Si dimers. These results are consistent with recent experimental studies of the system using the scanning tunneling microscopy (STM), and help to clarify some existing controversies on the interpretation of the STM images. In contrast, for Ge dimers on Ge(1 0 0), the most stable configuration is on top of the substrate dimer row. [Copyright &y& Elsevier]

Purpose: 5-Formyluracil (5-foU) is a major derivative of thymine produced in DNA by ionizing radiation and various chemical oxidants. It has been previously shown that 5-foU in template DNA directs misincorporation of nucleotides by DNA polymerases during in vitro DNA synthesis. The present experiments were designed to understand the biological effects of 5-foU in vivo. Materials and methods: The modified base was incorporated site-specifically into the recognition site of restriction endonuclease SalI (5′-GTCGAC) or AflII (5′-CTTAAG) in vector plasmid pSVK3 and introduced the plasmid into Escherichia coli. Results: When the plasmids were replicated in E. coli, 5-foU caused mutations at the target sites. The induced mutation frequencies were 0.038-0.049%. Sequence analysis revealed that 5-foU preferentially caused T:A → C:G and T:A → A:T base substitutions and -1 deletions at the 5-foU site. 5-FoU also caused mutations at sites near the 5-foU. The alkA mutation did not affect the frequency of mutations in 5-foU-containing plasmids. Conclusions: The present experiments demonstrated that 5-formyluracil in DNA caused mutations in E. coli. [ABSTRACT FROM AUTHOR]

Purpose: Escherichia coli HU protein exists as a heterodimer composed of two highly homologous subunits, HU-1 and HU-2, encoded by the hupB and hupA genes, respectively. It introduces negative supercoils into a relaxed circular DNA. Various roles of HU have been suggested in cellular processes such as DNA replication and transcription. The present experiments were designed to understand the role of HU in DNA repair processes in E. coli. Materials and methods: The sensitivity of hupAhupB mutants of E. coli to the lethal and mutagenic effects of UV was compared with that of a wild-type strain. The effect of the hupAhupB mutations in SOS induction was also examined. Results: The hupAhupB mutations increased the UV sensitivity of E. coli. Nucleotideexcision repair was unaffected by the deficiency of HU. On the other hand, E. coli hupAhupB mutants were sensitive to UV in the recA [sup +] recB [sup +] recF background but not in the recArecB [sup +] recF [sup +] or recA [sup +] recBrecF [sup +] background. The frequency of UV-induced mutation to rifampicin resistance was significantly reduced in the hupAhupB mutants, and the induction of the recA :: lacZ and umuC :: lacZ fusion genes was also suppressed in the mutants. Conclusions: HU protein plays a critical role in the recA, recB dependent recombinational DNA repair and SOS induction pathways in UV-irradiated E. coli. [ABSTRACT FROM AUTHOR]

More than a decade of active electrocaloric (EC) material research has produced several EC materials that exhibit a giant electrocaloric effect (ECE) at high electric fields, which is assured by direct measurement. These EC materials have enabled the demonstration of EC cooling devices, which exhibit temperature lifts of more than 10 K. These research and development efforts have revealed the critical importance of electrical breakdown, which is common in all electric and dielectric materials and devices under high voltages and electric fields. In general, the electric field for reliable device operation of dielectrics has to be less than 25% of the typical electric breakdown strength. To realize EC cooling devices with competitive performance requires advanced EC materials that generate large ECE (ΔT > 5 K) under these low electric fields. Double-bond (DB) defect modified P(VDF-TrFE-CFE) relaxor polymers, as reported recently, generate large ECE under low electric fields without any fatigue effects even after 1 × 106 field cycles. These relaxor ferroelectrics promise to meet the application challenge. A closely coupled experimental and theoretical study of EC materials will undoubtedly lead to advanced EC materials that generate large ECE at low electric fields beyond the DB modified relaxor polymers. This will result in practical and high-performance EC coolers, which are environmentally benign, compressor-free, and highly efficient. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the biological consequences of 5-formyluracil (5-foU) and 5-hydroxymethyluracil (5-hmU). Materials and methods: The authors constructed 22-mer oligonucleotides containing a 5-foU or 5-hmU residue at the same sites. The e ects of such modifications on the ability to serve as a template for DNA polymerase and on the cleavage by sequencespecific restriction endonuclease were examined. Results: The Klenow fragment of DNA polymerase I and Thermus thermophilus DNA polymerase read through the sites of 5-foU and 5-hmU in the templates. 5-FoU directed the incorporation of dCMP in addition to dAMP opposite the lesion during DNA synthesis. The DNA polymerases incorporated only dAMP opposite the 5-hmU. The substitution of thymine by 5-foU within the recognition site of the restriction endonucleases Hin cII and Sal I inhibited or prevented the cleavage by the enzymes, whereas the enzymes cleaved the 5-hmU-containing oligonucleotides at the same rate as the T-containing oligonucleotides. Conclusions: These results indicated that the 5-foU-A base pair is less stable than the T-A base pair and that 5-foU can form a base pair with C in addition to A. It was also demonstrated that the oxidation of thymine to 5-hmU does not result in substantial deterioration. [ABSTRACT FROM AUTHOR]

Two kinds of devices using N,N′-Di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) and dye-doped NPB as emitting layer were fabricated to study their magnetoconductance (MC) response. The MC of the NPB devices contains a positive low-field (0<|B|<40 mT) component but a negative high-field (|B|>40 mT) component at low temperatures. Similar MC is presented in the dye-doped NPB devices even at room temperature. Magnetoelectroluminescence results and energy-level diagram indicate that long lifetime triplet excitons and excessive holes are in these devices. All these observations suggest that triplet exciton-hole reaction is responsible for the negative MC while positive MC is assigned to hyperfine mixing of electron-hole pairs. [ABSTRACT FROM AUTHOR]

An electroactive polymer nanocomposite, in which high dielectric constant copper phthalocyanine oligomer (o-CuPc) nanoparticles are incorporated into the block polyurethane (PU) matrix by the combination of “top down” and “bottom up” approaches, was realized. Such an approach enables the nanocomposite to exhibit colossal dielectric and electromechanical responses with very low volume fraction of the high dielectric constant o-CuPc nanofillers (∼3.5%) in the composite. In contrast, a simple blend of o-CuPc and PU composite with much higher o-CuPc content (∼16% of o-CuPc) shows much lower dielectric and electromechanical responses. [ABSTRACT FROM AUTHOR]

In metal/insulator/metal sandwich structure, the interface between the metal and the insulator thin films plays significant roles in the functional performance of the thin films. In ferroelectric poly(vinylidene fluoride-trifluoroethylene) copylmer thin films metallized by different metals, it is found that the polarization switching is asymmetric due to the work function difference of the metal electrodes, and the degree of asymmetry increases with the increasing work function difference. For the samples with high work function metals as both or at least one of the electrodes, the polarization switching is much faster. The current–voltage curves at various temperatures indicated the interface-controlled asymmetric phenomena are mainly determined by the Schottky emission and charge injection at the metal/insulator polymer interface. [ABSTRACT FROM AUTHOR]

By combining the high-dielectric copper phthalocyanine oligomer (PolyCuPc) and conductive polyanline (PANI) within polyurethane (PU) matrix an all-organic three-component dielectric-percolative composite with high dielectric constant is demonstrated. In this three-component composite system, the high-dielectric-constant PolyCuPc particulates enhance the dielectric constant of the PU matrix and this combined two-component dielectric matrix in turn serves as the high-dielectric-constant host for the PANI to realize percolative phenomenon and further enhance the dielectric response. As a result, an electromechanical strain of 9.3% and elastic energy density of 0.4 J/cm3 under an electric field of 20 V/μm can be induced. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report here an all-polymer high-dielectric (dielectric constant K > 1000 at 1 kHz) percolative composite material, fabricated by a combination of conductive polyaniline particles (K>10[sup 5]) within a poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer matrix (K > 50). These high-K polymer hybrid materials also exhibit high electromechanical responses. For example, 1.5% strain, which is proportional to the square of the field applied, can be induced by a field of 9.5 MV/m, an eightfold reduction in field applied compared with that in a fluoroterpolymer matrix. [ABSTRACT FROM AUTHOR]