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Jie Luo, Yuting Yang, Zhongqi Yao, Weixin Lu, Bo Hou, Zhi Hong Hang, C T Chan, Yun Lai
By using pure dielectric photonic crystals, we demonstrate the realization of ultratransparent media, which allow near 100% transmission of light for all incident angles and create aberration-free virtual images. The ultratransparency effect is well explained by spatially dispersive effective medium theory for photonic crystals, and verified by both simulations and proof-of-principle microwave experiments. Designed with shifted elliptical equal frequency contours, such ultratransparent media not only provide a low-loss and feasible platform for transformation optics devices at optical frequencies, but also enable new freedom for phase manipulation beyond the local medium framework...
November 25, 2016: Physical Review Letters
Minkyung Kim, Sunae So, Kan Yao, Yongmin Liu, Junsuk Rho
Confining light into a sub-wavelength area has been challenging due to the natural phenomenon of diffraction. In this paper, we report deep sub-wavelength focusing via dispersion engineering based on hyperbolic metamaterials. Hyperbolic metamaterials, which can be realized by alternating layers of metal and dielectric, are materials showing opposite signs of effective permittivity along the radial and the tangential direction. They can be designed to exhibit a nearly-flat open isofrequency curve originated from the large-negative permittivity in the radial direction and small-positive one in the tangential direction...
December 7, 2016: Scientific Reports
J Buencuerpo, L Torné, R Álvaro, J M Llorens, M L Dotor, J M Ripalda
The moth-eye structure has been proposed several times as an antireflective coating to replace the standard optical thin films. Here, we experimentally demonstrate the feasibility of a dielectric moth-eye structure as an antireflective coating for high-index substrates, like GaAs. The fabricated photonic crystal has Si3N4 cones in a square lattice, sitting on top of a TiO2 index matching layer. This structure attains 1.4% of reflectance power losses in the operation spectral range of GaAs solar cells (440-870 nm), a 12...
December 7, 2016: Scientific Reports
Damien Thuau, Mamatimin Abbas, Guillaume Wantz, Lionel Hirsch, Isabelle Dufour, Cédric Ayela
The growth of micro electro-mechanical system (MEMS) based sensors on the electronic market is forecast to be invigorated soon by the development of a new branch of MEMS-based sensors made of organic materials. Organic MEMS have the potential to revolutionize sensor products due to their light weight, low-cost and mechanical flexibility. However, their sensitivity and stability in comparison to inorganic MEMS-based sensors have been the major concerns. In the present work, an organic MEMS sensor with a cutting-edge electro-mechanical transducer based on an active organic field effect transistor (OFET) has been demonstrated...
December 7, 2016: Scientific Reports
Hye-Hyeon Byeon, Woo Chul Lee, Wonbin Kim, Seong Keun Kim, Woong Kim, Hyunjung Yi
Single-walled carbon nanotubes (SWNTs) are one of the promising electronic components for nanoscale electronic devices such as field-effect transistors (FETs) owing to their excellent device characteristics such as high conductivity, high carrier mobility and mechanical flexibility. Localized gating gemometry of FETs enables individual addressing of active channels and allows for better electrostatics via thinner dielectric layer of high k-value. For localized gating of SWNTs, it becomes critical to define SWNTs of controlled nanostructures and functionality onto desired locations in high precision...
January 13, 2017: Nanotechnology
Junku Liu, Qunqing Li, Mo Chen, Mengxin Ren, Lihui Zhang, Lin Xiao, Kaili Jiang, Shoushan Fan
Graphene has proven to be a promising conductive layer in fabricating optical plasmon resonators on insulator substrate using electron beam lithography and has the potential to construct electrically controlled active plasmon resonators. In this study, we investigate the effect of graphene on plasmon resonance using graphene and Au plasmon resonator system as a model at visible and near-infrared wavelength. Our experiment data show that the presence of graphene does not weaken and annihilate the plasmon resonance peaks, instead it predominantly makes the peaks redshift, which is similar to the behavior of depositing SiO2 film on Au plasmon resonators...
December 2016: Nanoscale Research Letters
Guillermo Iván Guerrero-García, Francisco J Solis, Kalyan Raidongia, Andrew Robert Koltonow, Jiaxing Huang, Mónica Olvera de la Cruz
The current rectification displayed by solid-state p-n semiconductor diodes relies on the abundance of electrons and holes near the interface between the p-n junction. In analogy to this electronic device, we propose here the construction of a purely ionic liquid-state electric rectifying heterojunction displaying an excess of monovalent cations and anions near the interface between two immiscible solvents with different dielectric properties. This system does not need any physical membrane or material barrier to show preferential ion transfer but relies on the ionic solvation energy between the two immiscible solvents...
November 23, 2016: ACS Central Science
Naghme Dorraki, Vahideh Mahdavi, Hamid Ghomi, Alireza Ghasempour
The food industry is in a constant search for new technologies to improve the commercial sterilization process of agricultural commodities. Plasma treatment may offer a novel and efficient method for pesticide removal from agricultural product surfaces. To study the proposed technique of plasma food treatment, the degradation behavior of diazinon insecticide by air-dielectric barrier discharge (DBD) plasma was investigated. The authors studied the effect of different plasma powers and treatment times on pesticide concentration in liquid form and coated on the surface of cucumbers, where the diazinon residue was analyzed with mass spectroscopy gas chromatography...
December 6, 2016: Biointerphases
Yoshihiro Kubozono, Keita Hyodo, Shino Hamao, Yuma Shimo, Hiroki Mori, Yasushi Nishihara
A new phenacene-type molecule with five fused aromatic rings was synthesized: 2,7-didodecylphenanthro[2,1-b:7,8-b']dithiophene ((C12H25)2-i-PDT), with two terminal thiophene rings. Field-effect transistors (FETs) using thin films of this molecule were fabricated using various gate dielectrics, showing p-channel normally-off FET properties with field-effect mobilities (μ) greater than 1 cm(2) V(-1) s(-1). The highest μ value in the thin-film FETs fabricated in this study was 5.4 cm(2) V(-1) s(-1), when a 150 nm-thick ZrO2 gate dielectric was used...
December 6, 2016: Scientific Reports
Daniele Cei, Joana Costa, Giulia Gori, Gabriele Frediani, Claudio Domenici, Federico Carpi, Arti Ahluwalia
This study describes an actuated bioreactor which mimics the pulsatile contractile motion of the intestinal barrier using electro-responsive elastomers as smart materials that undergo deformation upon electrical stimulation. The device consists of an annular dielectric elastomer actuator working as a radial artificial muscle able to rhythmically contract and relax a central cell culture well. The bioreactor maintained up to 4 h of actuation at a frequency of 0.15 Hz and a strain of 8%-10%, to those of the cyclic contraction and relaxation of the small intestine...
December 5, 2016: Bioinspiration & Biomimetics
Longfang Ye, Yifan Xiao, Yanhui Liu, Liang Zhang, Guoxiong Cai, Qing Huo Liu
We demonstrate a novel route to achieving highly efficient and strongly confined spoof surface plasmon polaritons (SPPs) waveguides at subwavelength scale enabled by planar staggered plasmonic waveguides (PSPWs). The structure of these new waveguides consists of an ultrathin metallic strip with periodic subwavelength staggered double groove arrays supported by a flexible dielectric substrate, leading to unique staggered EM coupling and waveguiding phenomenon. The spoof SPP propagation properties, including dispersion relations and near field distributions, are numerically investigated...
December 5, 2016: Scientific Reports
Jacob Linder, Klaus Halterman
Exerting well-defined control over the reflection (R), absorption (A), and transmission (T) of electromagnetic waves is a key objective in quantum optics. To this end, one often utilizes hybrid structures comprised of elements with different optical properties in order to achieve features such as high R or high A for incident light. A desirable goal would be the possibility to tune between all three regimes of nearly perfect reflection, absorption, and transmission within the same device, thus swapping between the cases R → 1, A → 1, and T → 1 dynamically...
December 5, 2016: Scientific Reports
Mohamed S Seghilani, Mikhael Myara, Mohamed Sellahi, Luc Legratiet, Isabelle Sagnes, Grégoire Beaudoin, Philippe Lalanne, Arnaud Garnache
The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here "orbital birefringence", based on a dielectric metasurface...
December 5, 2016: Scientific Reports
Jijun Xiong, Guozhu Wu, Qiulin Tan, Tanyong Wei, Dezhi Wu, Sanmin Shen, Helei Dong, Wendong Zhang
The temperature sensor presented in this paper is based on a microwave dielectric resonator, which uses alumina ceramic as a substrate to survive in harsh environments. The resonant frequency of the resonator is determined by the relative permittivity of the alumina ceramic, which monotonically changes with temperature. A rectangular aperture etched on the surface of the resonator works as both an incentive and a coupling device. A broadband slot antenna fed by a coplanar waveguide is utilized as an interrogation antenna to wirelessly detect the sensor signal using a radio-frequency backscattering technique...
December 1, 2016: Sensors
U Sailaja, M ShahinThayyil, N S Krishna Kumar, G Govindaraj, K L Ngai
The dielectric properties of two pharmaceuticals nizatidine and perphenazine were investigated in the supercooled liquid and glassy states by broadband dielectric spectroscopy. Two relaxation processes were observed in both the pharmaceuticals. The relaxation process observed above the glass transition temperature is the structural alpha relaxation and below the glass transition temperature is the gamma relaxation of intramolecular origin. The Johari-Goldstein beta relaxation coming from the motion of the entire molecule is found to be hidden under the structural relaxation peak in both the pharmaceuticals...
December 1, 2016: European Journal of Pharmaceutical Sciences
Andrew W Wharmby
An empirical formula based on viscoelastic analysis techniques that employs concepts from the fractional calculus that was used to model the dielectric behavior of materials exposed to oscillating electromagnetic fields in the radiofrequency, terahertz, and infrared bands. This work adapts and applies the formula to model viscoelastic behavior of materials that show an apparent increase of phase velocity of vibration with an increase in frequency, otherwise known as anomalous dispersion. A fractional order wave equation is derived through the application of the classic elastic-viscoelastic correspondence principle whose analytical solution is used to describe absorption and dispersion of acoustic waves in the viscoelastic material displaying anomalous dispersion in a specific frequency range...
September 2016: Journal of the Acoustical Society of America
Mathias Schubert
A coordinate-invariant generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigendielectric displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations in the harmonic approximation. An expression for a general oscillator strength is also described for materials with monoclinic and triclinic crystal systems. A generalized factorized form of the dielectric response characteristic for monoclinic and triclinic materials is proposed...
November 18, 2016: Physical Review Letters
N V Lukasheva, D A Tolmachev, V M Nazarychev, J M Kenny, S V Lyulin
Specific intermolecular interactions, in particular H-bonding, have a strong influence on the structural, thermal and relaxation characteristics of polymers. We report here the results of molecular dynamics simulations of Nylon 6 which provides an excellent example for the investigation of such an influence. To demonstrate the effect of proper accounting for H-bonding on bulk polymer properties, the AMBER99sb force field is used with two different parametrization approaches leading to two different sets of partial atomic charges...
December 2, 2016: Soft Matter
Tobias Cramer, Lorenzo Travaglini, Stefano Lai, Luca Patruno, Stefano de Miranda, Annalisa Bonfiglio, Piero Cosseddu, Beatrice Fraboni
The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects...
December 2, 2016: Scientific Reports
A Imburgia, P Romano, M Caruso, F Viola, R Miceli, E Riva Sanseverino, A Madonia, G Schettino
The space charge accumulation phenomenon has garnered great interest over the last two decades because of the increased use of direct current in high voltage electrical systems. In this context, a significant relevance has been achieved by the thermal methods, used for solid dielectrics. This paper presents a review of this non-destructive measurement system used for the measurement of space charge. The thermal pulse method, the thermal step method, and the laser intensity modulation method are described. For each configuration, the principle of operation, the thicknesses analyzed, and the spatial resolution are described, reporting also the main related applications...
November 2016: Review of Scientific Instruments
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