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Qinghua Zhao, Tianshuo Zhao, Jiacen Guo, Wenxiang Chen, Mingliang Zhang, Cherie R Kagan
Doping, as a central strategy to control free carrier type and concentration in semiconductor materials, suffers from low efficiency at the nanoscale, especially in systems having high permittivity (ϵ) and large Bohr radii, such as lead chalcogenide nanocrystals (NCs) and nanowires (NWs). Here, we study dielectric confinement effects on the doping efficiency of lead chalcogenides nanostructures by integrating PbSe NWs in the platform of field effect transistors (FETs). Elemental Pb or In or elemental Se is deposited by thermal evaporation to remotely n- or p-dope the NWs...
January 18, 2018: ACS Nano
Luciano Mescia, Michele A Chiapperino, Pietro Bia, Johan Gielis, Diego Caratelli
During the past decades, the poration of cell membrane induced by pulsed electric fields has been widely investigated. Since the basic mechanisms of this process have not yet been fully clarified, many research activities are focused on the development of suitable theoretical and numerical models. To this end, a nonlinear, nonlocal, dispersive, and space-time numerical algorithm has been developed and adopted to evaluate the transmembrane voltage and pore density along the perimeter of realistic irregularly shaped cells...
February 2018: IEEE Transactions on Bio-medical Engineering
Xinlu Zhou, Kongshuang Zhao
A dielectric spectroscopy study on a polyelectrolyte in aqueous solutions, which contains hydrophobic groups in part of the side chains poly(acrylic acid)-graft-poly(ethylene oxide)-graft-dodecyl (PAA-g-PEO-g-dodecyl) is reported. A refined double layer polarization model was proposed to analyze the double dielectric relaxations in the dielectric spectra. Various electrical and structural parameters of the copolymers were obtained. Besides the crossover concentration, another turning point around 4 mg mL-1 was identified through the analysis of all the dielectrical parameters including dielectric increment, relaxation time and correlation length...
January 18, 2018: Soft Matter
Feiying Sun, Liangping Xia, Changbin Nie, Jun Shen, Yixuan Zou, Guiyu Cheng, Hao Wu, Yong Zhang, Dongshan Wei, Shaoyun Yin, Chunlei Du
The all-optical modulators based on graphene show great promise for on-chip optical interconnect. However, the modulation performance of all-optical modulators is usually based on graphene and fiber interaction, limiting their potential in high integration. Based on this point, the all-optical modulator in dielectric-loaded waveguide (DLW) with graphene-silicon heterojunction structure (GSH) is proposed. The DLW raises the waveguide mode which provides a strong light-graphene interaction. And sufficient tuning of graphene Fermi energy beyond the Pauli blocking effect is obtained with the presented GSH structure...
January 18, 2018: Nanotechnology
Andrey Yu Sosorev, Dmitry Yu Godovsky, Dmitry Yu Paraschuk
The modeling of organic solar cells (OSCs) can provide a roadmap for their further improvement. Many OSC models have been proposed in recent years; however, the impact of the key intermediates from photons to electricity-hot charge-transfer (CT) states-on the OSC efficiency is highly ambiguous. In this study, we suggest an analytical kinetic model for OSC that considers a two-step charge generation via hot CT states. This hot kinetic model allowed us to evaluate the impact of different material parameters on the OSC performance: the driving force for charge separation, optical bandgap, charge mobility, geminate recombination rate, thermalization rate, average electron-hole separation distance in the CT state, dielectric permittivity, reorganization energy and charge delocalization...
January 18, 2018: Physical Chemistry Chemical Physics: PCCP
Kenji Ikeda, Nobukiyo Kobayashi, Ken-Ichi Arai, Shin Yabukami
The magnetoelectric effect is a key issue for material science and is particularly significant in the high frequency band, where it is indispensable in industrial applications. Here, we present for the first time, a study of the high frequency tunneling magneto-dielectric (TMD) effect in nanogranular FeCo-MgF films, consisting of nanometer-sized magnetic FeCo granules dispersed in an MgF insulator matrix. Dielectric relaxation and the TMD effect are confirmed at frequencies over 10 MHz. The frequency dependence of dielectric relaxation is described by the Debye-Fröhlich model, taking relaxation time dispersion into account, which reflects variations in the nature of the microstructure, such as granule size, and the inter-spacing between the granules that affect the dielectric response...
January 15, 2018: Journal of Magnetism and Magnetic Materials
Rui Zhu, Xuannan Wu, Yidong Hou, Gaige Zheng, Jianhua Zhu, Fuhua Gao
Optical diode-like effect has sparked growing interest in recent years due to its potential applications in integrated photonic systems. In this paper, we propose and numerically demonstrate a new type of easy-processing metal/dielectric cylinder composite grating on semi-sphere substrate, which can achieve high-contrast asymmetric transmission of unpolarized light for the sum of all diffraction modes in the entire visible region, and effectively guide the diffraction light transmitting out the substrate. The asymmetric light transmission (ALT) ratio is larger than 2 dB in the waveband from 380 nm to 780 nm and the maximum ALT ratio can reach to 13 dB at specified wavelengths...
January 17, 2018: Scientific Reports
Jung-Shen B Tai, Paul J Ackerman, Ivan I Smalyukh
Liquid crystals are widely known for their facile responses to external fields, which forms a basis of the modern information display technology. However, switching of molecular alignment field configurations typically involves topologically trivial structures, although singular line and point defects often appear as short-lived transient states. Here, we demonstrate electric and magnetic switching of nonsingular solitonic structures in chiral nematic and ferromagnetic liquid crystals. These topological soliton structures are characterized by Hopf indices, integers corresponding to the numbers of times that closed-loop-like spatial regions (dubbed "preimages") of two different single orientations of rod-like molecules or magnetization are linked with each other...
January 17, 2018: Proceedings of the National Academy of Sciences of the United States of America
Paul Brunet, Rocío Rincón, Zineb Matouk, Mohamed Chaker, Françoise Massines
Nanocomposite thin films formed of TiO2 in a polymer-like matrix are grown in a filamentary Argon (Ar) Dielectric Barrier Discharge (DBD) from a suspension of TiO2 nanoparticles in isopropanol (IPA). The sinusoidal voltage producing the plasma is designed to independently control the matrix growth rate and the transport of nanoparticles (NPs) aggregates to the surface. The useful FSK (Frequency Shift Keying) modulation mode is chosen to successively generate two sinusoidal voltages: a high frequency signal at 15 kHz and a low frequency signal at frequencies ranging from 0...
January 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ken-Ichi Nomura, Yoshinori Horii, Shusuke Kanazawa, Yasuyuki Kusaka, Hirobumi Ushijima
We fabricate a wearable blood leakage sensor on a cotton textile by combining two newly developed techniques. First, we employ a screen-offset printing technique that avoids blurring, short circuiting between adjacent conductive patterns, and electrode fracturing to form an interdigitated electrode structure for the sensor on a textile. Furthermore, we develop a scheme to distinguish blood from other substances by utilizing the specific dielectric dispersion of blood observed in the sub-megahertz frequency range...
January 15, 2018: Sensors
F Riboli, F Uccheddu, G Monaco, N Caselli, F Intonti, M Gurioli, S E Skipetrov
We present experimental evidence for the different mechanisms driving the fluctuations of the local density of states (LDOS) in disordered photonic systems. We establish a clear link between the microscopic structure of the material and the frequency correlation function of LDOS accessed by a near-field hyperspectral imaging technique. We show, in particular, that short- and long-range frequency correlations of LDOS are controlled by different physical processes (multiple or single scattering processes, respectively) that can be-to some extent-manipulated independently...
July 28, 2017: Physical Review Letters
Meng Shen, Honghao Li, Monica Olvera de la Cruz
Surface polarization in ion-containing heterogeneous dielectric media such as cell media and emulsions is determined by and determines the positions of the ions. We compute the surface polarization self-consistently as the ions move and analyze their effects on the interactions between electro-neutral, ion-containing droplets using coarse-grained molecular dynamics simulations based on the true energy functional. For water droplets immersed in oil, the interdroplet interaction is attractive, and the surface polarization makes the major contribution...
September 29, 2017: Physical Review Letters
Wei Liu
We propose generalized magnetic mirrors that can be achieved by excitations of sole electric resonances. Conventional approaches to obtain magnetic mirrors rely heavily on exciting the fundamental magnetic dipoles, whereas here we reveal that, besides magnetic resonances, electric resonances of higher orders can be also employed to obtain highly efficient magnetic mirrors. Based on the electromagnetic duality, it is also shown that electric mirrors can be achieved by exciting magnetic resonances. We provide direct demonstrations of the generalized mirrors proposed in a simple system of a one-dimensional periodic array of all-dielectric wires, which may shed new light on many advanced fields of photonics related to resonant multipolar excitations and interferences...
September 22, 2017: Physical Review Letters
Jose Navarrete, Chris Siefe, Samuel Alcantar, Michael Belt, Galen D Stucky, Martin Moskovits
Metallic nanostructures exhibit a strong plasmon resonance at a wavelength whose value is sensitive to the charge density in the nanostructure, its size, shape, interparticle coupling and the dielectric properties of its surrounding medium. Here we use UV-Visible transmission and reflectance spectroscopy to track the shifts of the plasmon resonance in an array of gold nanoparticles buried under metal-oxide layers of varying thickness produced using atomic layer deposition (ALD), then coated with bulk layers of one of three metals: aluminum, silver, and gold...
January 17, 2018: Nano Letters
Arash Darafsheh, Jeffrey E Melzer, James A Harrington, Alireza Kassaee, Jarod C Finlay
Manifestation of Čerenkov radiation as a contaminating signal is a significant issue in radiation therapy dose measurement by fiber-coupled scintillator dosimeters. To enhance the scintillation signal transmission while minimizing Čerenkov radiation contamination, we designed a fiber probe using a silver-only coated hollow waveguide (HWG). The HWG with scintillator inserted in its tip, embedded in tissue-mimicking phantoms, was irradiated with clinical electron and photon beams generated by a medical linear accelerator...
January 2018: Journal of Biomedical Optics
Tenghao Yin, Danming Zhong, Junjie Liu, Xiangjiang Liu, Honghui Yu, Shaoxing Qu
The tunable diffracted pattern (Debye ring) of the well-ordered close-packed 2D photonic crystal (PC) is achieved via large deformation of the dielectric elastomer (DE) membrane for the first time. Two deformation models are proposed, the in-plane deformation driven by voltage and the out-of-plane deformation actuated by pressure. Both experimental and theoretical analyses are conducted to explore the tunability of the DE stretch on the Debye ring of the 2D PC, by voltage and pressure. An excellent agreement is found between the experimental and analytical results...
January 17, 2018: Soft Matter
Xiaojia Jia, Canek Fuentes-Hernandez, Cheng-Yin Wang, Youngrak Park, Bernard Kippelen
Organic thin-film transistors (OTFTs) can be fabricated at moderate temperatures and through cost-effective solution-based processes on a wide range of low-cost flexible and deformable substrates. Although the charge mobility of state-of-the-art OTFTs is superior to that of amorphous silicon and approaches that of amorphous oxide thin-film transistors (TFTs), their operational stability generally remains inferior and a point of concern for their commercial deployment. We report on an exhaustive characterization of OTFTs with an ultrathin bilayer gate dielectric comprising the amorphous fluoropolymer CYTOP and an Al2O3:HfO2 nanolaminate...
January 2018: Science Advances
Yinghui Guo, Mingbo Pu, Xiong Li, Xiaoliang Ma, Ping Gao, Yanqin Wang, Xiangang Luo
Starting with the early works of extraordinary optical transmission and total extinction, researchers have been fascinated by the unusual optical properties displayed by metallic holes/slits and subsequently found similar abnormities in dielectric counterparts. Benefiting from the shrinking wavelength of SPPs excited in metallic slits and high refractive index of dielectric stripes, one can realize local phase modulation and approach desired dispersion by engineering the geometries of slits and stripes array...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Luís F S Mendes, Luis G M Basso, Patricia S Kumagai, Raquel Fonseca-Maldonado, Antonio J Costa-Filho
BACKGROUND: Golgi Reassembly and Stacking Proteins (GRASPs) are widely spread among eukaryotic cells (except plants) and are considered as key components in both the stacking of the Golgi cisternae and its lateral connection. Furthermore, GRASPs were also proved essential in the unconventional secretion pathway of several proteins, even though the mechanism remains obscure. It was previously observed that the GRASP homolog in Cryptococcus neoformans has a molten globule-like behavior in solution...
January 12, 2018: Biochimica et Biophysica Acta
Swadipta Roy, C V Ramana
We report on the tunable and controlled dielectric properties of iron (Fe)-doped gallium oxide (Ga2O3; Ga1.9Fe0.1O3, referred to as GFO) inorganic compounds. The GFO materials were synthesized using a standard high-temperature, solid-state chemical reaction method by varying the thermochemical processing conditions, namely, different calcination and sintering environments. Structural characterization by X-ray diffraction revealed that GFO compounds crystallize in the β-Ga2O3 phase. The Fe doping has induced slight lattice strain in GFO, which is evident in structural analysis...
January 17, 2018: Inorganic Chemistry
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