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Metamaterials with large-scale freestanding Ag-SU-8-Ag sandwich configuration, perforated with a square periodic array of circular holes, are fabricated. The transmittance spectra of both experiment and simulation have shown the existence of two transmittance peaks in the middle-infrared region. Numerical simulations based on the effective media method and the effective parameter retrieval procedure verify that the low-frequency transmittance peak results from the electric and the magnetic resonance associated with the negative refractive index. The influence of dielectric loss of the interlayer on transmission and negative refractive response is discussed. Numerical simulations indicate that the transmission within the negative refractive index region decreases, while the dielectric loss of interlayer increase, mainly due to the enhanced reflection. Moreover, the electric resonance mode further increases the absorption resulted from the dielectric loss of interlayer. [ABSTRACT FROM AUTHOR]

Neuropeptide Y (NPY) from enteric neurons has been shown to play an important role in immune and inflammatory responses. The purpose of the present study was to investigate the effects of NPY antisense oligodeoxynucleotides (ODNs) on an experimental model of ulcerative colitis (UC). NPY antisense ODNs were administered in experimental colitis induced by dextran sulfate sodium (DSS). The disease activity index (DAI) and histological score were observed. The tumor necrosis factor (TNF)-α and NPY levels were measured by enzyme-linked immunosorbent assay. Phosphorylated Akt (p-Akt) expression was determined by immunohistochemical staining. Activated nuclear factor (NF)-κB was assessed by western blot analysis. Myeloperoxidase (MPO) activity was determined by using MPO assay kit. A significant improvement was observed in DAI and histological score in rats with NPY antisense ODNs, and the increase in NPY and TNF-α levels, MPO activity, and the expression p-Akt and p-NF-κB in rats with DSS-induced colitis was significantly reduced following the administration of NPY antisense ODNs. The administration of NPY antisense ODNs leads to an amelioration of DSS-induced colitis, suggesting that NPY plays an important role in modulating inflammation in colitis, and NPY antisense ODNs may be a useful therapeutic approach to the treatment of UC. [ABSTRACT FROM AUTHOR]

A novel composite phase-shifting transmission line (TL) with designable characteristics is presented, which can be used to achieve arbitrary phase of the transmission coefficient at any required frequency with a certain length of the TL. An empirical formula is given of the relationship between the phase and physical length of the composite TL at a required frequency. A sample of 0 phase-shifting TL is designed in details, and is verified by the full-wave simulation. At the required frequency of 5 GHz, the amplitude of S21 is equal to -0.23 dB with a phase of -0.467°. The electric length is only 0.21λ0, which has been decreased by 68.5% compared to the conventional microstrip line. Using the proposed composite TL, an antenna array is designed with two radiation patches excited by the novel series feed-line. The detailed procedure of such design is presented. The lowest reflection coefficient is exactly achieved at the required frequency of 5 GHz. The maximum radiation is obtained at θ0 = O°, which indicates that the 0 phase-shifting TL works very well. The sample is also fabricated and good agreements between simulation and measurement results are obtained. [ABSTRACT FROM AUTHOR]

An efficient approach is proposed to analyze the electromagnetic scattering from objects above a 2-D perfectly electric conducting rough surface. A half-space Green's function with the rough-surface interface is first derived from the Kirchhoff approximation (KA). The method of moments is then applied to analyze the scattering problem of 3-D arbitrarily shaped objects above the rough surface. Since only the objects need to be discretized, the computational time and memory requirement are greatly reduced. The radar cross sections of typical objects above the rough surface have been computed using the proposed method. Numerical results show that the proposed method has good accuracy in the valid range of KA. [ABSTRACT FROM AUTHOR]

Abstract  Silages are important feedstuffs. Homofermentative lactic acid bacterial inoculants are often used to control silage fermentation. However, some research pointed out those homofermentative lactic acid bacteria (LAB) impaired the aerobic stability of wheat, sorghum, and corn silages. Adding heterofermentative LAB can produce more acetic acid, thereby stabilizing silages during aerobic exposure. Alfalfa is difficult to ensile. The present work was to study the effects of L. buchneri (heterofermentative LAB), alone or in combination with L. plantarum (homofermentative LAB) on the fermentation, aerobic stability, bacteria diversity and ruminal degradability of alfalfa silage. After 90 days ensiling, the pH, NH3-N/TN, butyric acid content and molds counts of control were the highest. The inoculated silages had more lactic acid, acetic acid content and more lactic acid bacteria than the control. Inoculating LAB inhibited harmful microorganisms, such as Enterobacterium and Klebsiella pneumoniae. The L. buchneri + L. plantarum-inoculated silage had more acetic acid and less yeasts than other three treatments (P 3-N/TN than control (P 2 production of L. buchneri + L. plantarum-inoculated silage was less than that of L. plantarum-inoculated silage (P Enterobacterium and K. pneumoniae. Inoculating with L. buchneri or L. buchneri + L. plantarum can improve aerobic stability of alfalfa silages. A combination of L. buchneri and L. plantarum is preferable because it enhanced alfalfa silage quality and aerobic stability. [ABSTRACT FROM AUTHOR]

We propose an accurate numerical method to compute the electromagnetic scattering from three-dimensional (3D) arbitrarily shaped objects composed of inhomogeneous and biaxial metamaterials, whose permittivity and permeability are both anisotropic. The basic theory for the numerical method is to set up the linear equations by the method of moments (MOM) with pulse basis functions and point matching. The resulting matrix equation is solved by the conjugate gradient (CG) method combined with the fast Fourier transform (FFT) to reduce the storage requirements and CPU time of the computer. The accuracy of the proposed CG-FFT method has been validated. We have applied the method to investigate scattering by penetrable particles with inhomogeneous and anisotropic permittivity and permeability, which will be important and helpful to analyse the scattering characteristics of metamaterials. Finally, a large 3D gradient-index lens has been investigated by using the proposed method, and the numerical result has a good match to the theoretical prediction. [ABSTRACT FROM AUTHOR]

Aim: A cross-section study was conducted to explore the association between polymorphism of δ-aminolevulinic acid dehydratase (ALAD) and lead poisoning in Uygur and Han children in China. Methods: The ALAD genotyping was determined by PCR-RFLP in 443 Uygur and 469 Han children aged 6–10 years from Urumqi in Xinjiang province. Results: The blood lead levels of 912 environmentally exposed children ranged from 0.5 to 48.2 μg/dL, with a mean of 5.45 μg/dL and a standard deviation of 0.22 μg/dL, and 23. Thirty-one percent individuals were with blood lead level ≥10 μg/dL. The mean and standard deviation of blood lead levels were 5.57 ± 0.223 μg/dL and 5.30 ± 0.224 μg/dL in Uygur and Han children, respectively. The frequencies of the allele ALAD1 and ALAD2 in Uygur subjects were 90.52% and 9.48%, and in Han subjects were 95.73% and 4.27%, respectively (chi-square = 19.55, p < 0.05). No statistic correlation between the distribution of ALAD alleles and the blood lead level was found in both populations. Conclusion: A significant difference was seen in the frequency distribution of ALAD genotype between the different races. The genetic susceptibility of ALAD polymorphism to lead toxicity may exhibit in a lead dose-dependent manner. [ABSTRACT FROM AUTHOR]

Objective--To evaluate the changes in concentrations of matrix metalloproteinase (MMP)- 2 and MMP-9 in the precorneal tear film of dogs with Pseudomonas aeruginosa-associated keratitis during corneal healing and stromal remodeling. Animals--10 dogs with unilateral P aeruginosa-associated keratitis and 10 clinically normal dogs. Procedures--Precorneal tear film samples were collected from both eyes of 10 dogs with unilateral Paeruginosa-associated keratitis on the day of admission to the hospital and then at various time points until complete healing of the cornea was achieved. Precorneal tear film samples were also collected from both eyes of 10 clinically normal adult dogs (control group). Concentrations of MMP-2 and MMP-9 in precorneal tear film samples from each group were determined via gelatin zymography for comparison. Results--The proteolytic processes in the ulcerated eyes decreased as corneal healing progressed. On the day of admission, concentrations of latent and active forms of MMP- 2 and MMP-9 in ulcerated eyes were significantly higher than values in the contralateral unaffected eyes in dogs with P aeruginosa-associated keratitis; concentrations of latent MMP-2 and MMP-9 were also greater than control group values. Concentrations of latent and active forms of MMP-2 and MMP-9 in the healed eyes of dogs with P aeruginosa-associated keratitis were significantly lower than concentrations in the ulcerated eyes on the day of admission. Conclusions and Clinical Relevance--Results suggest that reduction of precorneal tear film concentrations of MMPs by use of proteinase inhibitors may be effective in the treatment of dogs with P aeruginosa-associated keratitis. [ABSTRACT FROM AUTHOR]

With solvent molecules participating in coordination systems, four new Mn IIcoordination polymers of the rigid ligand 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (H 2BDC-Cl 4) have been obtained from different solvent media. Single-crystal X-ray analysis indicates that the coordination arrays of 1− 4vary from 1D fishbone or zigzag chain for 1or 2, 2D (4,4) layer for 3, to 3D SrAl 2coordination network for 4, respectively. In {[Mn(BDC-Cl 4)(py) 2(H 2O) 2](py) 2} n( 1) and {[Mn(BDC-Cl 4)(MeOH) 3](MeOH)} n( 2), pyridine/water (in 1) and MeOH (in 2) molecules act as the monodentate terminal ligands to fulfill the metal coordination spheres. In the case of {[Mn(BDC-Cl 4)(dioxane)(H 2O) 2](dioxane)} n( 3), the aqua ligand is monodentate and the dioxane moiety displays unusual bridging bidentate mode, whereas for [Mn 5(BDC-Cl 4) 5(DMF) 5] n( 4), three Mn IIcenters are connected by four BDC-Cl 4ligands and two DMF molecules to constitute a trimeric unit. These secondary units are extended to the final 3D network with SrAl 2( sra) topology. Significantly, the solvents play an essential role in the crystallization and construction of these coordination frameworks with distinct dimensionality and connectivity. The thermal and photoluminescence properties of complexes 1− 4in the solid state have also been discussed. [ABSTRACT FROM AUTHOR]

An efficient method is presented to design the evanescent wave amplification exactly by cascading two layers of periodic series-shunt capacitors and inductors, which simulate a bilayer of magnetic and electric plasmas. Based on the presented method, equivalent lumped parameters of circuit structures are retrieved, from which the evanescent-wave amplification (EWA) is obtained at a designed frequency. Full-wave simulations show that the relative offset of the EWA frequency is less than 0.1%. The structure has been fabricated and measured, and the measurement results have good agreements with the simulation results. The proposed method can be used to design other periodic circuit structures, and the exact design of EWA can be used in the fabrication of novel components. © Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1870–1873, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23501 [ABSTRACT FROM AUTHOR]

Objective To determine the bacterial microorganisms in the conjunctival sac of clinically normal dogs and dogs with ulcerative keratitis in Beijing, China. The effect of breed, sex and age of dogs and season on the presence or absence of bacteria in the conjunctival sac of clinically normal dogs was evaluated. Sample population This investigation included 240 healthy dogs, 27 dogs with unilateral corneal ulcer and one dog with bilateral corneal ulcer. Procedure The 480 samples from healthy dogs and the 29 samples from dogs with ulcerative keratitis were incubated in an aerobic and 5% CO2 environment at 37 °C for 48 h. Logistic regression analysis was performed. Statistical significance was set at P < 0.01. Results Of 480 normal eyes, Staphylococcus spp. were the most frequently isolated organisms (40.29%). Neisseria spp. (11.47%) were the next most frequently isolated organisms, followed by Corynebacterium spp. (9.4%). Of 29 eyes with ulcerative keratitis, Staphylococcus spp. were also the most frequently isolated bacteria (47.06%). Streptococcus spp. (12.94%) and Pseudomonas spp. (8.24%) were the second and third, respectively. Season ( P = 0.002) was a significant factor influencing presence or absence of bacterial microorganisms in the conjunctival sac of normal dogs in Beijing, China, while the effects of breed ( P = 0.095), sex ( P = 0.588) and age ( P = 0.866) of dogs were insignificant. Conclusion Staphylococcus spp. were the most frequently isolated organisms, and S. intermedius predominated in the conjunctival sac of clinically normal dogs and dogs with ulcerative keratitis in Beijing, China. The likelihood of detecting bacteria depends on the season. [ABSTRACT FROM AUTHOR]

Abstract  Spatial variations of δD and δ18O among seven tributaries and their water sources were investigated in the Heishui Valley of the Yangtze River, China during the dry-season in 2004. A one-way ANOVA (analysis of variation) test showed that both δD (p 18O (p = 0.045) spatially varied among the seven tributaries. The plot of δ18O versus δD for the river water collected at different locations showed that isotopic fractionation occurred during the snow and glacial melting process. The depleted δ18O and δD in the tributary waters distributed above the local meteoric water line (LMWL) suggested that the glacial and early snowpack meltwater largely recharged these streams during the early spring. The meltwater was isotopically distinguishable from the precipitation and river water, which had been evaporated during warmer and drier times. If glaciers and snow accumulation diminish with future climate warming, the recharge of these tributaries’ baseflow will decline and the security of the water resource in this watershed will be threatened. [ABSTRACT FROM AUTHOR]

Abstract: Native copper mineralization in northeastern Yunnan is related to the Emeishan flood basalts, which have high Cu background concentrations. The deposits are located in the Ludian, Maoling and Yiche synclines between the flood basalts and the overlying Xuanwei Formation. Evidence from REE and HSFE concentrations, oxygen isotope compositions, bitumen reflectance, and mineral paragenesis indicates that the high-grade copper orebodies were deposited from moderate to low temperature hydrothermal solutions (420 to 100°C) in a reducing environment. 40Ar/39Ar spectra for the laumontites that coexist with native copper in the high-grade ores yield consistent plateau and isochron ages (226 to 228Ma). These are interpreted to represent the age of the first stage of hydrothermal mineralization, which took place at temperatures of 200 to350°C, concordant with that of Zn–Pb–Ag–Ge mineralization also occurring in the area. The heulandites yield a stable 40Ar/39Ar plateau age of 134.0±1.7Ma, consistent with isochron ages indicated by U–Th–Pb isotopic systematics, indicating a second stage of native copper mineralization at lower temperatures (100 to 200°C) that took place during the Early Cretaceous. [Copyright &y& Elsevier]

This paper presents a novel compact meta-structure, which is characterized by left-handed properties. In the novel structure, two linear arrays of metallic vias and short-stub inductors are used to generate shunt inductors besides the series interdigital capacitors. Compared with conventional composite right/left-handed transmission-line structures, the new structure has weaker coupling to other components and is easily controlled by adjusting the shunt inductance and series capacitance to produce different left-handed properties. Due to the isolation of two via arrays, the proposed structure can also be transplanted directly from the microstrip system to the coplanar-waveguide system. We have proposed an efficient procedure to retrieve the equivalent propagating modes for both forward and backward waves based on the matrix pencil method, which provides an easy way to study the propagation characteristics. Using such a meta-structure, a series of super-wide bandpass filters are designed and fabricated at different frequency bands. Good agreements between simulation and experiment results have been achieved, and good performance in passbands and stopbands has been observed with a relative 3-dB bandwidth larger than 70%. For easy design of such super-wide bandpass filters, an experienced formula is given between the physical size and the center frequency of the 3-dB passband, which can be used to redesign any filters at other frequency bands. [ABSTRACT FROM AUTHOR]

Abstract: Geophysical (Electrical Resistivity Tomography, Ground Penetrating Radar profiles and seismic refraction) and geotechnical (dynamic penetrometer, in situ vane test) surveys were carried out at Garchy (Nièvre, France). The main objective of this study was to establish qualitative and quantitative correlations between electrical and geotechnical data from this site in a simple geological context. Concerning qualitative correlations, geotechnical tests and Electrical Resistivity Tomography sections are consistent with a three-layers model: a fine soil with a significant clay fraction sandwiched between a low moisture sandy soil and oolitic limestones. Despite the usual difficulty to locate clearly interfaces in inverted ERT sections, both methods provide consistent depths of the substratum top. Moreover, this study confirms that correlations between reflectors of GPR profiles and vertical geotechnical property variations are mainly explained by vertical water content changes. As far as quantitative correlations are concerned, no clear relationship between cone resistance and inverted resistivity extracted from ERT sections has been observed. Nevertheless, if we do not consider the upper sandy soil composed with gravels, the couple inverted resistivity–cone resistance would be a lithological discriminator. This lithological discrimination is enhanced when inverted resistivity values obtained from extracted 1D soundings are considered. This original result should be validated in other sites. Moreover, a satisfactory quantitative correlation between inverted resistivity values and measured water content values has been obtained; this correlation demonstrates once more that resistivity is a good indirect predictor of water content. [Copyright &y& Elsevier]

We present elemental abundance measurements for nine damped Lyman α (Lyα) systems (DLAs) and one sub-DLA at from recent observations with the Multiple Mirror Telescope (MMT). Most of these absorbers are found to be metal poor, while two are found to have ≈30–50 per cent solar metallicities. Combining our data with other data from the literature, we find that the systems with higher [Zn/H] also have stronger depletion as measured by [Cr/Zn] and [Fe/Zn]. The relationship between the metallicity and H i column density is also investigated. Together with our previous MMT survey, we have discovered two of the four known absorbers at that lie above (although near) the ‘obscuration threshold’. This appears to be a result of selecting absorbers with strong metal lines in our sample. It would be interesting to find other similar systems by observing a larger sample and study how much such systems contribute to the cosmic budget of metals. Finally, an analysis of the NH i-weighted mean metallicity versus redshift for our sample combined with data from the literature supports previous conclusions that the NH i-weighted mean global DLA metallicity rises slowly at best and falls short of solar levels by a factor of >4 even at z= 0. [ABSTRACT FROM AUTHOR]

Microwave components with nonlinear phase responses are developed using a simplified composite right/left-handed (CRLH) transmission-line (TL) structure without the series capacitance or the shunt inductance. Using such a simplified CRLH structure, arbitrarily dual-band microstrip components have been realized in compact sizes such as a quarter-wavelength short-circuited stub and dual-band branch-line couplers. Simulation and measurement results are given to demonstrate the efficiency and good performance of the proposed components. For the quarter-wavelength short-circuited stub based on the simplified CRLH-TL structure without the series capacitance, it has been shown that the insertion loss is less than -0.1 dB. For the arbitrarily dual-band branch-line coupler, experiment results exhibit that $21 and $31 are larger than -3.6 dB, the isolations are smaller than -30 dB, the return losses are smaller than -20 dB, and the phase differences are within 90° ± 1.8°. [ABSTRACT FROM AUTHOR]

A multilevel algorithm that efficiently Fourier transforms sparse spatial data to sparse spectral data with controllable error is presented. The algorithm termed "sparse data fast fourier transform" (SDFFT) is particularly useful for signal processing applications where only part of the k-space is to be computed--regardless of whether it is a regular region like an angular section of the Ewald sphere or it consists of completely arbitrary points scattered in the k-space. In addition, like the various nonuniform fast Fourier transforms, the O(N log N) algorithm can deal with a sparse, nonuniform spatial domain. In this paper, the parabolic reflector antenna problem is studied as an example to demonstrate its use in the computation of far-field patterns due to arbitrary aperture antennas and antenna arrays. The algorithm is also promising for various applications such as back-projection tomography, diffraction tomography, and synthetic aperture radar imaging. [ABSTRACT FROM AUTHOR]

In multilayer microwave integrated circuits such as low-temperature co-fired ceramics or multilayered printed circuit boards, waveguide-like structures can be fabricated by using periodic metallic via-holes referred to as substrate integrated waveguide (SIW). Such SIW structures can largely preserve the advantages of conventional rectangular waveguides such as high-Q factor and high power capacity. However, they are subject to leakage due to periodic gaps, which potentially results in wave attenuation. Therefore, such a guided-wave modeling problem becomes a very complicated complex eigen value problem. Since the SIW are bilaterally unbounded, absorbing boundary conditions should be deployed in numerical algorithms. This often leads to a difficult complex root-extracting problem of a transcend equation. In this paper, we present a novel finite-difference frequency-domain algorithm with a perfectly matched layer and Floquet's theorem for the analysis of SIW guided-wave problems. In this scheme, the problem is converted into a generalized matrix eigen value problem and finally transformed to a standard matrix eigen value problem that can be solved with efficient subroutines available. This approach has been validated by experiment. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of two cryptic plasmids isolated from Lactobacillus plantarum strain AS1.2986 has been determined. The smaller plasmid, designated pLP2000, encodes a 37.0 kDa Rep protein and has a 17 bp sequence repeated 10 times. Sequence analysis of the larger plasmid, designated pLP9000, revealed nine putative open reading frames (ORFs). Based on sequence similarity, ORF1 codes for a putative magnesium transporter protein that shows similarities to CorA from plasmid pCIS3 (Lactococcus lactis). None of the nine ORFs shows similarity to any known Rep protein. Southern blot analysis indicates these two plasmids both replicate via a rolling circle (RC) mechanism. [Copyright &y& Elsevier]

A band-stop filter based on spoof surface plasmon polaritons for microwave applications is proposed, which can realise high-efficiency band rejections by etching gradient semi-circular grooves on both sides of the middle stripline of coplanar waveguide. The operating bandwidth and frequency of band-stop can be controlled by changing the radii of semi-circular holes and the length of unit cell, respectively. The operating principle of the designed band-stop filter is explained by the dispersion curves and electric field distributions. Parametric studies are also conducted to analyse the effects of key parameters on the performance of the band-stop filter, which is useful for practical designs. A prototype of the band-stop filter is fabricated and measured. The good agreements between the simulated and measured results validate the proposed design, which indicate that the presented band-stop filter can be potentially useful in many microwave applications. [ABSTRACT FROM AUTHOR]

The article discusses the technological innovations in mobile communication with a major focus on ultra reliable low latency communications (URLLC) in fifth generation networks. Topics discussed include the importance of multiple-input multiple-output (MIMO) antennas, programmable metasurface for transmitting wavelengths and innovation in high-resolution videos and 4K virtual reality.

We show that the radially anisotropic zero-index metamaterials can be used to realize spatial power combination within fan-shaped regions. When the radial component of the permittivity or permeability tensor tends to zero, the coherent omnidirectional radiations will occur when sources are within the fan-shaped metamaterial backed with perfect magnetic conductors (PMCs), which leads to spatial power combination in finite areas. As the included angle of the PMC corner reflector decreases, the powers from internal sources can still be efficiently combined, which has potential applications in radio frequency engineering. [ABSTRACT FROM AUTHOR]

Here we present a facile synthesis of crystalline polyaniline (PANI) with dendritic morphology by a slow vapour phase chemical oxidative polymerization, which opens up possibility for further understanding PANI's chain elaborately arranged, crystal structure model, and essence of the molecular interaction. [ABSTRACT FROM AUTHOR]

We propose a class of optical transformation media, illusion media, which render the enclosed object invisible and generate one or more virtual objects as desired. We apply the proposed media to design a microwave device, which transforms an actual object into two virtual objects. Such an illusion device exhibits unusual electromagnetic behavior as verified by full-wave simulations. Different from the published illusion devices which are composed of left-handed materials with simultaneously negative permittivity and permeability, the proposed illusion media have finite and positive permittivity and permeability. Hence the designed device could be realizable using artificial metamaterials. [ABSTRACT FROM AUTHOR]

A planar lens made of gradient index metamaterials can transform cylindrical waves to plane waves, and the beam direction of plane waves is controlled by adjusting the refractive-index distributions of the lens. Based on such properties, we present high-performance beam-scanning antennas experimentally using the gradient-index planar lens and horn antenna. The lens is carefully designed with metamaterials to achieve different refractive indices and good matching of impedance. The near-field distributions of antennas are measured using a two-dimensional near-field microwave scanning apparatus, and the radiation patterns are presented to show the high directivity and low sidelobe. [ABSTRACT FROM AUTHOR]

Metamaterials are artificially structured materials that provide considerable flexibility for control of electromagnetic waves. The metamaterial concept can also be applied to the design of planar waveguiding structures. Here, we illustrate this design approach with the development of two-dimensional (2D) planar gradient index (GRIN) circuits. To form the structure, we make use of a 2D complementary split ring resonator, which exhibits an electric response to guided transverse-electric waves. To confirm the properties of the planar GRIN structure predicted from numerical simulations, we present experimental results for a beam-steering and a focusing GRIN circuit. These examples illustrate the versatility of the metamaterial approach in the design of complex waveguiding structures. [ABSTRACT FROM AUTHOR]

The orientation, chirality, and dynamics of solar eruptive filaments are key to our understanding of the magnetic field of coronal mass ejections (CMEs), and therefore to predicting the geoeffectiveness of CMEs arriving at Earth. However, confusion and contention remain over the relationship between the filament chirality, magnetic helicity, and the sense of rotation during eruption. To resolve the ambiguity in observations, in this paper we used stereoscopic observations to determine the rotation direction of filament apex and the method proposed by Chen et al. to determine the filament chirality. Our sample of 12 eruptive active-region filaments establishes a strong one-to-one relationship, i.e., during the eruption, sinistral/dextral filaments (located in the southern/northern hemisphere) rotate clockwise/counterclockwise when viewed from above, and corroborates a weak hemispheric preference, i.e., a filament and related sigmoid both exhibit a forward (reverse) S shape in the southern (northern) hemisphere, which suggests that the sigmoidal filament is associated with a low-lying magnetic flux rope with its axis dipped in the middle. As a result of rotation, the projected S shape of a filament is anticipated to be reversed during eruption. [ABSTRACT FROM AUTHOR]

We present a polarization-selective transmission-type 2 bit coding metasurface (MS) to achieve dual-band performance, in which the operating frequency band is adjustable between the lower (Ku-band) and higher (K-band) bands by changing the polarization of the linearly polarized incident wave. Three coding MS devices are designed by using specific coding sequences of the proposed coding meta-atoms. Firstly, two coding MSs are presented for vortex beam generation that carries orbital angular momentum with different topological charges in the two operating bands. Secondly, a coding MS is proposed to anomalously refract the cross-polarized field with different deflection angles in the two frequency bands. Finally, the proposed scheme is extended to design a coding MS that focuses the transmitted fields at two frequencies by changing the polarization of the incident wave. Furthermore, the proposed designs are valid to perform the same functions for waves propagating along both the ‘+z’ and ‘−z’ directions in the same frequency bands but with orthogonal polarizations of incident waves. The sign of the topological charge can be altered by changing the direction of propagation from ‘+z’ to ‘−z’. To demonstrate the easiness of implementations, experiments of the fabricated samples are performed for the vortex beam generation and focusing. We believe that the proposed method may find potential applications in the future optical devices for multi-spectrum and multi-function operations. [ABSTRACT FROM AUTHOR]

Multiple band-rejection filters based on spoof surface plasmon polaritons (SPPs) are designed in dual frequency bands using interactions between spoof SPP waveguide and metamaterial particles. The multi-band rejections are achieved by etching π-type decorations on the spoof SPP waveguide. More importantly, the bandwidths, isolation and shifting of the rejection frequencies of filters can be controlled very efficiently by varying different geometrical parameters of the π-type decorations. Both numerical and experimental results are demonstrated to verify the large flexibility and excellent functionality of the multiple band-rejection filters in both lower and higher frequency bands. We are fully confident that the use of two frequency bands in realizing multiple band-rejections filtering by the proposed spoof SPP waveguide makes it unique in giving a boost to the development of plasmonic integrated circuits and systems. [ABSTRACT FROM AUTHOR]

Surface plasmon can lead to wave propagation not only along the surface as a dielectric waveguide but also in the normal direction to the surface because of the evanescent-wave amplification by metamaterial. In this letter, the authors design a surface plasmon structure to implement the electric and magnetic plasma resonances in microwave regime. Near the plasma resonant frequency, they directly observe the strong surface plasmon by experiments. The evanescent waves can be transmitted in an exponentially increasing and decreasing distribution, which is the evanescent-mode propagation by the tunneling effect. [ABSTRACT FROM AUTHOR]

We propose an anisotropic digital coding metasurface to realize arbitrarily polarized retro-reflections. With the theoretical support of generalized Snell's laws, the proposed coding metasurface shows excellent performance of retro-reflections through reflection phase design. A modified metallic Jerusalem cross structure is employed to achieve the required phase profile under oblique incidence due to its good performance in polarization isolation. By changing the length of coding particle's arms, the particle can be digitally named as '00', '01', '10' and '11' elements with different phase responses. Through special design of phase gradient, the coding metasurface can reflect incident waves backwards for arbitrary polarizations, which can be decomposed into transverse electric and transverse magnetic polarizations. A prototype was fabricated and measured. Both simulation and experiment results verify the good performance of the arbitrarily polarized retro-reflections by the metasurface. [ABSTRACT FROM AUTHOR]

Magnetic flux ropes (MFRs) are thought to be the central structures of solar eruptions, and their ideal MHD instabilities can trigger the eruption. Here we performed a study of all the MFR configurations that lead to major solar flares, either eruptive or confined, from 2011 to 2017 near the solar disk center. The coronal magnetic field is reconstructed from observed magnetograms, and based on magnetic twist distribution, we identified the MFR, which is defined as a coherent group of magnetic field lines winding an axis with more than one turn. It is found that 90% of the events possess pre-flare MFRs, and their three-dimensional structures are much more complex in details than theoretical MFR models. We further constructed a diagram based on two parameters, the magnetic twist number which controls the kink instability (KI), and the decay index which controls the torus instability (TI). It clearly shows lower limits for TI and KI thresholds, which are ncrit = 1.3 and , respectively, as all the events above ncrit and nearly 90% of the events above erupted. Furthermore, by such criterion, over 70% of the events can be discriminated between eruptive and confined flares, and KI seems to play a nearly equally important role as TI in discriminating between the two types of flares. More than half of the events with both parameters are below the lower limits, and 29% are eruptive. These events might be triggered by magnetic reconnection rather than MHD instabilities. [ABSTRACT FROM AUTHOR]

The thin thickness and the working efficiency are always two key problems for transmission-type polarization conversion devices. Here, we propose a C-band ultrathin (0.02 λ0 in the thickness) and highly efficient circular-polarization conversion device in the transmission mode. The designer wave plate is composed of double layer surface structures printed on both sides of a single-layer substrate and the metallic layers are connected by a pair of through-via holes. The structure of the top layer is composed of a patch with a D-shape slot inside, and the bottom layer can be obtained by rotating the top layer with 180 degrees around the center. We demonstrate that the designer wave plate can achieve transmission polarization conversion from right-handed circularly polarized incident electromagnetic (EM) waves to left-handed ones or from left-handed circularly polarized incident EM waves to right-handed ones in the transmission mode. The results show that the maximum cross-polarization conversion efficiency of the designer wave plate at a working frequency of 5.8 GHz is 94.6%. This ultra-thin circular-polarization conversion device is expected to be applied to wireless systems that require circular polarization diversity. [ABSTRACT FROM AUTHOR]

The measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are analyzed for the basic properties of solar wind stream interaction regions (SIRs) and their associated shocks at 1.52 au, as well as the evolution of SIRs from 1 to 1.52 au. A total of 149 SIRs are identified during the period from 2014 October to 2018 November, and 126 SIRs with high-quality data are selected for this study. The average occurrence rate of SIRs at 1.52 au is 36.3 yr−1, which is comparable to but slightly higher than that (32.4 yr−1) at 1 au, meaning that most SIRs are well formed at 1 au. The average duration of SIRs at 1.52 au is about 37.0 hr, comparable to that at 1 au (36.73 hr), indicating that SIRs have not yet expanded more rapidly as they are convected to 1.52 au. The maximum magnetic field strength and pressure of SIRs decrease significantly from 1 to 1.52 au. The shock association rates of SIRs increase from 20.3% to 33.3% or higher as SIRs evolve from 1 to 1.52 au. The forward shocks tend to occur twice more frequently than the reverse shocks. About 75% of shocks at 1.52 au are quasi-perpendicular shocks. The strength of the shocks becomes weaker and the average shock speed remains almost unchanged from 1 to 1.52 au. These results will help us understand the solar wind conditions at Mars and their potential impact on the Martian space environment. [ABSTRACT FROM AUTHOR]

A second emission enhancement in warm coronal extreme-ultraviolet (EUV) lines (about 2–7 MK) during some solar flares is known as the EUV late phase. Imaging observations confirm that the late-phase emission originates from a set of longer or higher loops than the main flare loops. Nevertheless, some questions remain controversial: What is the relationship between these two loop systems? What is the heating source of late-phase emission? Does heating accompany the main-phase heating or does it occur quite later? In this paper, we present clear evidence for a heating source in a late-phase solar flare: magnetic reconnection of the overlying field in a quadrupolar magnetic configuration. The event is triggered by an erupted core structure that eventually leads to a coronal mass ejection. A cusp feature and its shrinkage motion high in the late-phase emission region are manifestations of the later phase reconnection following the main flare reconnection. Using the enthalpy-based thermal evolution of loops model, we reasonably reproduce the late-phase emissions in some EUV lines. We suggest that continuous additional heating is responsible for the appearance of the elongated EUV late phase. [ABSTRACT FROM AUTHOR]

Metasurfaces provide the freedom to manipulate electromagnetic (EM) waves by controlling the peculiarity of subwavelength artificial structures. Many exciting devices have been developed using metasurfaces that can even perform multiple functionalities. In this paper, we propose to transform linearly polarized EM waves into high-order orbital angular momentum (OAM) beams and specifically reflected split beams for different polarizations based on anisotropic coding metasurfaces. By means of precisely adjusting the geometry of the element structure, the reflection phases of two perpendicular polarizations can be encoded without interference, which is conductive to encode the metasurfaces independently in two different directions. Under this benefit, two kinds of 2-bit phase-coded metasurfaces are constructed and verified by experiments to demonstrate their versatility of generating effective high-order OAM beams and specified reflected split beams, respectively. Beyond that, by adjusting the coding scheme, more features can be implemented under this merit. [ABSTRACT FROM AUTHOR]

The surging demand for miniaturized compact devices has generated the need for new metal conductors with high current carrying ampacity, electric and thermal conductivity. Herein, we report carbon-metal conductors that exhibit a high breakdown current density (39% higher than copper) and electrical conductivity (e.g. 63% higher than that of copper at 363 K) in a broad temperature range. The mechanistic studies of thermal conductivity through first-principle modeling show that the multilayer graphene percolation networks efficiently decrease the electron-phonon coupling in the copper-graphene composites, even if phonon modes are activated at a high temperature. These results imply that the copper-based composites have the potential to be the next generation metal conductor with high electrical and thermal conductivity, as well as excellent current-carrying ampacity. More importantly, the developed composite can be deployed in the ink form, making it possible to be utilized by the microelectronic fabrication process. [ABSTRACT FROM AUTHOR]

An illusion device based on a shifting-distance concept has been investigated using a linear coordinate transformation method. Distinguishing it from previously designed illusion devices, we construct a shift-illusion device featuring resizing and rotating for both active and passive scatterers, in case the shifting region and physical space shared the same origin point. Similarly, when the shifting region is foreign to the designed device, the proposed illusion design performs as a rotation and relocation-shifting device to change the location of the scatterer. In addition, these proposed devices behave like the stealth effect in the absence of any scatterer as the outer-boundary field distribution is not disturbed. Meanwhile, the proposed concept is further extended for different mapping styles to validate the shifting-illusion concept. The constitutive parameters of the proposed devices are homogeneous, which makes them more appreciable for real implementation. It is expected that the proposed design will find potential applications in illusion devices, such as object protection, camouflage, etc. [ABSTRACT FROM AUTHOR]

Owing to the gorgeous features of planar design, strong field confinement, and compatibility with traditional microwave devices, spoof surface plasmon polaritons (SSPPs) have been developing at a rapid pace in modern microwave technologies. Band-rejection filters, especially multi-band rejection filters, are a significant ecosystem of SSPPs to be designed. Here, we firstly propose compact multi-band rejection filters, including dual-band and triple-band, through the addition of interdigital capacitance loaded loop resonators (IDCLLRs) into the grooves of the corrugated SSPP transmission line (TL). Compared to traditional metamaterial particles like split ring resonators (SRRs) and complementary SRRs (CSRRs) with the same size, IDCLLRs possess excellent merits of lower resonant frequency, larger dynamic range, and more tunable parameters, which enable the proposed device to be more compact and have more freedom for adjusting bandwidths. Both the simulated and experimental results demonstrate the high performance of two multi-band rejection filters, which can provide wide stop-bandwidth (a maximum relative bandwidth of up to 9.5% for the dual-band filter and 8.8% for the triple-band filter) and high isolation (the isolation of both filters can be less than  −30 dB and the maximum isolation of up to  −60 dB for the dual-band filter and  −58 dB for the triple-band filter). The compact SSPP filters with adjustable multi-band rejections may greatly advance progress towards SSPP-based devices and integrated systems. [ABSTRACT FROM AUTHOR]

We propose dynamically tunable dual-band perfect absorption of light in a composite structure, which consists of a graphene ribbon array coated on a dielectric layer, a silicon carbide (SiC) film and a distributed Bragg reflector (DBR). Two absorption peaks reaching 98.8% at 10.87 μm and 97.5% at 12.4 µm are observed in the hybrid structure. The dual-band absorption enhancement can be explained by two different mechanisms: one is attributed to the graphene localized surface plasmons (GLSP), and the other is originated from the excitation of Tamm plasmon polaritons (TPP) at the interface between SiC and DBR. Moreover, the high absorption peaks can be modulated by altering the geometrical parameters or dynamically controlling the chemical potential of graphene ribbons. More significantly, we numerically and theoretically investigate the hybridization between GLSP mode and TPP mode, which is characterized by the anti-crossing behaviour of the two modes. The mode splitting phenomenon is a typical Rabi splitting. In addition, we also study the coupling characteristics based on graphene surface plasmons (GSP) mode and TPP mode. This work offers a new paradigm for enhancing light–matter interaction through multiple resonance modes, and the proposed device could provide potential applications in MIR plasmonic devices, such as absorbers, detectors, and modulators, etc. [ABSTRACT FROM AUTHOR]

We propose a dual-band transmission-type digital coding metasurface, whose band selection is determined by the polarization state of the incident electromagnetic waves. Cross-polarized transmitted fields are obtained from the designed digital coding particle consisting of cascaded metallic structures and dielectric substrates. In each band, various shaped-beam patterns are achieved by designing different coding sequences on the coding metasurface. The structure is proposed to operate in two separately operating bands for transverse-electric and transverse-magnetic incident polarizations in ‘+z’ and ‘−z’ propagation directions. In addition to the beam-shaping performance, asymmetric transmission is also realized in the two operating bands. Experiments are performed in the microwave regime for the verification of simulation results in both operating bands. [ABSTRACT FROM AUTHOR]

In this paper, we analyzed a failed and a successful eruption that initiated from the same polarity inversion line within NOAA AR 11387 on 2011 December 25. They both started from a reconnection between sheared arcades, with distinct pre-eruption conditions and eruption details: before the failed one, the magnetic fields of the core region had a weaker non-potentiality; the external fields had a similar critical height for torus instability, and a similar local torus-stable region, but a larger magnetic flux ratio (of low corona and near-surface region) compared to the successful one. During the failed eruption, a smaller Lorentz force impulse was exerted on the outward ejecta; the ejecta had a much slower rising speed. Factors that might lead to the initiation of the failed eruption are identified: (1) a weaker non-potentiality of the core region, and a smaller Lorentz force impulse gave the ejecta a small momentum; (2) the large flux ratio, and the local torus-stable region in the corona provided strong confinements that made the erupting structure regain an equilibrium state. [ABSTRACT FROM AUTHOR]

A new macroscopic multidirectional cloak scheme for extraordinary rays is proposed by controlling the optical axes of uniaxial crystals. It eliminates the complicated material constraints and can also be utilized to design a cloaking device for ordinary rays or isotropic cloaks after simplification. Numerical ray tracing and full-wave simulation results validate our design. Moreover, if the uniaxial crystals are changed into other materials whose optical axes can be modulated, like liquid crystals, this scheme has the potential to fabricate direction-tunable cloaks. [ABSTRACT FROM AUTHOR]

A new method is proposed to design gradient refractive-index metamaterial lens antennas by optimizing both the refractive-index distribution of the lens and the feed directivity. Comparing to the conventional design methods, source optimization provides a new degree of freedom to control aperture fields effectively. To demonstrate this method, two lenses with special properties based on this method are designed, to emit high-efficiency plane waves and fan-shaped beams, respectively. Both lenses have good performance and wide frequency band from 12 to 18 GHz, verifying the validity of the proposed method. The plane-wave emitting lens realized a high aperture efficiency of 75%, and the fan-beam lens achieved a high gain of 15 dB over board bandwidth. The experimental results have good agreement with the design targets and full-wave simulations. [ABSTRACT FROM AUTHOR]

We develop a model for calculating the radiation force on spherically symmetric multilayered particles based on the acoustic scattering approach. An expression is derived for the radiation force on a multilayered sphere centered on the axis of a Gaussian standing wave propagating in an ideal fluid. The effects of the sound absorption of the materials and sound wave on acoustic radiation force of a multilayered sphere immersed in water are analyzed, with particular emphasis on the shell thickness of every layer, and the width of the Gaussian beam. The results reveal that the existence of particle trapping behavior depends on the choice of the non-dimensional frequency ka, as well as the shell thickness of each layer. This study provides a theoretical basis for the development of acoustical tweezers in a Gaussian standing wave, which may benefit the improvement and development of acoustic control technology, such as trapping, sorting, and assembling a cell, and drug delivery applications. [ABSTRACT FROM AUTHOR]

The energetic particle environment of the lunar nearside is quite different from that of the lunar farside. Due to the shielding of the Earth’s magnetosphere and the Moon, the lunar nearside may receive much fewer energetic particles from the Sun. It is currently impossible to directly measure the received energetic particle flux of the whole lunar surface. By using the ARTEMIS and Wind observations, we qualitatively studied the shielding effect of the Earth’s magnetosphere and the lunar body from solar energetic particles (SEPs). We found that the Earth’s magnetosphere can effectively shield SEPs with energies up to 4 Mev during the SEP event. However, in the solar wind, the Moon can provide partial shielding from SEPs with energies ≤100 KeV. SEPs with energies above 150 KeV in the lunar shadow show no difference in flux from in the solar wind, which suggests that the nearside and farside are the same in receiving SEPs with energies above 150 KeV during the SEP event. [ABSTRACT FROM AUTHOR]

The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. Here we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g−1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as  −7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress–strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti2Ni precipitates typically one micron in size with a large aspect ratio enclosing the TiNi matrix. A stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti2Ni precipitates is believed to be the origin of the unique superelasticity behavior. [ABSTRACT FROM AUTHOR]

Rare-earth free permanent magnet MnBi (NiAs-type crystal structure) displays strong uniaxial magnetic anisotropy above its ~90 K spin reorientation transition (SRT). X-ray magnetic circular dichroism (XMCD) measurements at the Mn K and Bi L2,3 edges show induced magnetism in Bi, which is strongly coupled to the magnetism of Mn. Temperature- and pressure-dependent XMCD results reveal that hydrostatic pressure mimics the effect of temperature, driving a transition from uniaxial to in-plane anisotropy. The pressure and temperature transitions are shown to be connected to an anisotropic lattice contraction in NiAs-type structures. Temperature and pressure, hence, induce coupled structural and magnetic responses, highlighting the importance of both anisotropic lattice change and Mn-Bi hybridization in leading to the magnetic anisotropy change across the SRT. The dependence of magnetic anisotropy on the anisotropic lattice change is confirmed by density functional theory. [ABSTRACT FROM AUTHOR]