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Sample records for nano-dielectric sphere covered

  1. Light Scattering by a Dielectric Sphere: Perspectives on the Mie Resonances

    Directory of Open Access Journals (Sweden)

    Dimitrios Tzarouchis

    2018-01-01

    Full Text Available Light scattering by a small spherical particle, a central topic for electromagnetic scattering theory, is here considered. In this short review, some of the basic features of its resonant scattering behavior are covered. First, a general physical picture is described by a full electrodynamic perspective, the Lorenz–Mie theory. The resonant spectrum of a dielectric sphere reveals the existence of two distinctive types of polarization enhancement: the plasmonic and the dielectric resonances. The corresponding electrostatic (Rayleigh picture is analyzed and the polarizability of a homogeneous spherical inclusion is extracted. This description facilitates the identification of the first type of resonance, i.e., the localized surface plasmon (plasmonic resonance, as a function of the permittivity. Moreover, the electrostatic picture is linked with the plasmon hybridization model through the case of a step-inhomogeneous structure, i.e., a core–shell sphere. The connections between the electrostatic and electrodynamic models are reviewed in the small size limit and details on size-induced aspects, such as the dynamic depolarization and the radiation reaction on a small sphere are exposed through the newly introduced Mie–Padé approximative perspective. The applicability of this approximation is further expanded including the second type of resonances, i.e., the dielectric resonances. For this type of resonances, the Mie–Padé approximation reveals the main character of the two different cases of resonances of either magnetic or electric origin. A unified picture is therefore described encompassing both plasmonic and dielectric resonances, and the resonant conditions of all three different types are extracted as functions of the permittivity and the size of the sphere. Lastly, the directional scattering behavior of the first two dielectric resonances is exposed in a simple manner, namely the Kerker conditions for maximum forward and

  2. Geometrical-optics code for computing the optical properties of large dielectric spheres.

    Science.gov (United States)

    Zhou, Xiaobing; Li, Shusun; Stamnes, Knut

    2003-07-20

    Absorption of electromagnetic radiation by absorptive dielectric spheres such as snow grains in the near-infrared part of the solar spectrum cannot be neglected when radiative properties of snow are computed. Thus a new, to our knowledge, geometrical-optics code is developed to compute scattering and absorption cross sections of large dielectric particles of arbitrary complex refractive index. The number of internal reflections and transmissions are truncated on the basis of the ratio of the irradiance incident at the nth interface to the irradiance incident at the first interface for a specific optical ray. Thus the truncation number is a function of the angle of incidence. Phase functions for both near- and far-field absorption and scattering of electromagnetic radiation are calculated directly at any desired scattering angle by using a hybrid algorithm based on the bisection and Newton-Raphson methods. With these methods a large sphere's absorption and scattering properties of light can be calculated for any wavelength from the ultraviolet to the microwave regions. Assuming that large snow meltclusters (1-cm order), observed ubiquitously in the snow cover during summer, can be characterized as spheres, one may compute absorption and scattering efficiencies and the scattering phase function on the basis of this geometrical-optics method. A geometrical-optics method for sphere (GOMsphere) code is developed and tested against Wiscombe's Mie scattering code (MIE0) and a Monte Carlo code for a range of size parameters. GOMsphere can be combined with MIE0 to calculate the single-scattering properties of dielectric spheres of any size.

  3. The electromagnetic radiation from simple sources in the presence of a homogeneous dielectric sphere

    Science.gov (United States)

    Mason, V. B.

    1973-01-01

    In this research, the effect of a homogeneous dielectric sphere on the electromagnetic radiation from simple sources is treated as a boundary value problem, and the solution is obtained by the technique of dyadic Green's functions. Exact representations of the electric fields in the various regions due to a source located inside, outside, or on the surface of a dielectric sphere are formulated. Particular attention is given to the effect of sphere size, source location, dielectric constant, and dielectric loss on the radiation patterns and directivity of small spheres (less than 5 wavelengths in diameter) using the Huygens' source excitation. The computed results are found to closely agree with those measured for waveguide-excited plexiglas spheres. Radiation patterns for an extended Huygens' source and for curved electric dipoles located on the sphere's surface are also presented. The resonance phenomenon associated with the dielectric sphere is studied in terms of the modal representation of the radiated fields. It is found that when the sphere is excited at certain frequencies, much of the energy is radiated into the sidelobes. The addition of a moderate amount of dielectric loss, however, quickly attenuates this resonance effect. A computer program which may be used to calculate the directivity and radiation pattern of a Huygens' source located inside or on the surface of a lossy dielectric sphere is listed.

  4. Electric field of not completely symmetric systems earthed sphere-uniformly charged dielectric plan

    International Nuclear Information System (INIS)

    Vila, F.

    1994-07-01

    In this paper we study theoretically the electric field in the not completely symmetric system, earthed metallic sphere-uniformly charged dielectric plan, for sphere surface points situated in the plan that contains sphere's center and vertical symmetry axe of dielectric plan. (author). 11 refs, 1 fig

  5. The scattering properties of anisotropic dielectric spheres on electromagnetic waves

    International Nuclear Information System (INIS)

    Chen Hui; Zhang Weiyi; Wang Zhenlin; Ming Naiben

    2004-01-01

    The scattering coefficients of spheres with dielectric anisotropy are calculated analytically in this paper using the perturbation method. It is found that the different modes of vector spherical harmonics and polarizations are coupled together in the scattering coefficients (c-matrix) in contrast to the isotropic case where all modes are decoupled from each other. The generalized c-matrix is then incorporated into our codes for a vector wave multiple scattering program; the preliminary results on face centred cubic structure show that dielectric anisotropy reduces the symmetry of the scattering c-matrix and removes the degeneracy in photonic band structures composed of isotropic dielectric spheres

  6. Influence of dielectric polarization upon PD transients: Use of hollow dielectric spheres

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1997-01-01

    Hollow glass spheres have recently been employed to provide a reproducible source of partial discharges. The influence of the shell permittivity upon the PD transients is examined. It is shown that, relative to the non-shell situation, the magnitude of such transients may be increased or decrease......, depending on the ratio of the shell-to-bulk dielectric permittivities....

  7. Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

    International Nuclear Information System (INIS)

    Jamil, Saba; Janjua, Muhammad Ramzan Saeed Ashraf; Ahmad, Tauqeer; Mehmood, Tahir; Li, Songnan; Jing, Xiaoyan

    2014-01-01

    Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability

  8. Enhancing local absorption within a gold nano-sphere on a dielectric surface under an AFM probe

    International Nuclear Information System (INIS)

    Talebi Moghaddam, Sina; Ertürk, Hakan; Mengüç, M. Pınar

    2016-01-01

    This study considers enhancing localized absorption by a gold nanoparticle (NP) placed over a substrate where an atomic force microscope (AFM) tip is in close proximity of the particle. The gold NP and AFM tip are interacting with a surface evanescent wave, resulting a near-field coupling between the tip and NP and consequently enhances the absorption. This concept can be used for selective heating of NPs placed over a surface that enables precise manufacturing at nanometer scales. Different tip positions are considered to identify the optimal tip location and the corresponding enhancement limits. The effects of these interactions on the absorption profiles of dielectric core/gold shell NPs are also studied. It is observed that using core–shell nanoparticles with a dielectric core leads to further enhancement of the absorption efficiency and a more uniform distribution of absorption over the shell. Discrete dipole approximation coupled with surface interactions (DDA-SI) is employed throughout the study, and it is vectorized to improve its computational efficiency. - Highlights: • Plasmonic coupling between solid or core-shell nanoparticles, dielectric surface and Si AFM tip is investigated for achieving localized heating for nano-manufacturing. • Absorption efficiency enhancement limits for core-shell and solid nanoparticles are identified using an AFM tip for surface evanescent wave heating. • The effect of tip location, relative to surface wave direction is outlined, identifying optimal locations, and heat absorption distribution over core-shell and solid nanoparticles. • While using a Si AFM tip enhances absorption, using a dielectric core result in further enhancement in absorption with a more uniform distribution. • DDA-SI-v developed by vectorizing the formulations of DDA-SI for improved computational efficiency.

  9. Ultrasonic electrodeposition of silver nanoparticles on dielectric silica spheres

    International Nuclear Information System (INIS)

    Tang Shaochun; Tang Yuefeng; Gao Feng; Liu Zhiguo; Meng Xiangkang

    2007-01-01

    In the present study, a facile and one-step ultrasonic electrodeposition method is first applied to controllably coat colloidal silica spheres with silver nanoparticles. This method is additive-free and very direct, because processes necessary in many other approaches, such as pretreatment of the silica sphere surface and pre-preparation of silver nanoparticles, are not involved in it. Furthermore, it makes possible the coating of dielectric substrates with metal through an electrodeposition route. Under appropriate conditions, silver nanoparticles with sizes of 8-10 nm in diameter can be relatively homogeneously deposited onto the surface of preformed colloidal silica spheres. Silver particles with different sizes and dispersive uniformity on silica sphere surfaces can also be obtained by adjusting the current density (I), the concentration of electrolyte (C) and the electrolysis time (t). The possible ultrasonic electrodeposition mechanism is also suggested according to the experimental results

  10. Analytical solutions of nonlocal Poisson dielectric models with multiple point charges inside a dielectric sphere

    Science.gov (United States)

    Xie, Dexuan; Volkmer, Hans W.; Ying, Jinyong

    2016-04-01

    The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.

  11. Optical pulling force on a magneto-dielectric Rayleigh sphere in Bessel tractor polarized beams

    International Nuclear Information System (INIS)

    Mitri, F.G.; Li, R.X.; Yang, R.P.; Guo, L.X.; Ding, C.Y.

    2016-01-01

    The optical radiation force induced by Bessel (vortex) beams on a magneto-dielectric subwavelength sphere is investigated with particular emphasis on the beam polarization and order l (or topological charge). The analysis is focused on identifying the regions and some of the conditions to achieve retrograde motion of the sphere centered on the axis of wave propagation of the incident beam, or shifted off-axially. Exact non-paraxial analytical solutions are established, and computations for linear, circular, radial, azimuthal and mixed polarizations of the individual plane wave components forming the Bessel (vortex) beams by means of the angular spectrum decomposition method (ASDM) illustrate the theory with particular emphasis on the tractor (i.e. reversal) behavior of the force. This effect results in the pulling of the magneto-dielectric sphere against the forward linear momentum density flux associated with the incoming waves. Should some conditions related to the choice of the beam parameters as well as the permittivity and permeability of the sphere be met, the optical force vanishes and reverses sign. Moreover, the beam polarization is shown to affect differently the axial negative pulling force for either the zeroth- or the first-order Bessel beam. When the sphere is centered on the beam′s axis, the axial force component is always negative for the zeroth-order Bessel beam except for the radial and azimuthal polarization configurations. Nonetheless, for the first-order Bessel beam, the axial force is negative for the radial polarization case only. Additional tractor beam effects arise when the sphere departs from the center of the beam. It is also demonstrated that the tractor beam effect arises from the force component originating from the cross-interaction between the electric and magnetic dipoles. Potential applications are in particle manipulation, optical levitation, tractor beam tweezers, and other emergent technologies using polarized Bessel beams on

  12. Scattering of linearly polarized Bessel beams by dielectric spheres

    Science.gov (United States)

    Shoorian, Hamed

    2017-09-01

    The scattering of a Linearly Polarized Bessel Beam (LPBB) by an isotropic and homogenous dielectric sphere is investigated. Using analytical relation between the cylindrical and the spherical vector wave functions, all the closed- form analytical expressions, in terms of spherical wave-functions expansions, are derived for the scattered field. It is shown that in the case of conical angle of incident Bessel beam is equal to zero, the Linearly Polarized Bessel Beam becomes a plane wave and its scattering coefficients become the same as the expansion coefficients of plane wave in Mie theory. The transverse Cartesian and spherical components of the electric field, scattered by a sphere are shown in the z-plane for different cases, moreover the intensity of the incident Bessel beam and the effects of its conical angle on the scattered field and the field inside the sphere are investigated. To quantitatively study the scattering phenomenon and the variations of the fields inside and outside of the sphere, the scattering and absorption efficiencies are obtained for the scattering of the linearly-polarized Bessel beam, and are compared with those of the plane wave scattering.

  13. LDPE/HDPE/Clay Nano composites: Effects of Compatibilizer on the Structure and Dielectric Response

    International Nuclear Information System (INIS)

    David, Z.E.; Ngo, A.D.

    2013-01-01

    PE/clay nano composites were prepared by mixing a commercially available premixed polyethylene/O-MMT master batch into a polyethylene blend matrix containing 80 wt% low-density polyethylene and 20 wt% high-density polyethylene with and without anhydride modified polyethylene (PE-MA) as the compatibilizer using a corotating twin-screw extruder. In this study, the effect of nano clay and compatibilizer on the structure and dielectric response of PE/clay nano composites has been investigated. The microstructure of PE/clay nano composites was characterized using wide-angle X-ray diffraction (WAXD) and a scanning electron microscope (SEM). Thermal properties were examined using differential scanning calorimetry (DSC). The dielectric response of neat PE was compared with that of PE/clay nano composite with and without the compatibilizer. The XRD and SEM results showed that the PE/O-MMT nano composite with the PE-MA compatibilizer was better dispersed. In the nano composite materials, two relaxation modes are detected in the dielectric losses. The first relaxation is due to a Maxwell-Wagner-Sillars interfacial polarization, and the second relaxation can be related to dipolar polarization. A relationship between the degree of dispersion and the relaxation rate f m ax of Maxwell-Wagner-Sillars was found and discussed.

  14. Nanoporous CuS nano-hollow spheres as advanced material for high-performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Moosavifard, Seyyed Ebrahim, E-mail: info_seyyed@yahoo.com [Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Elyasi, Saeed [Department of Chemical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Shahraki, Mohammad [Department of Chemistry, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2017-02-01

    Highlights: • Nanoporous CuS nano-hollow spheres were synthesized by a facile method. • Nano-hollow spheres have a large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). • Such unique structures exhibit excellent electrochemical properties for high-performance SCs. - Abstract: Due to unique advantages, the development of high-performance supercapacitors has stimulated a great deal of scientific research over the past decade. The electrochemical performance of a supercapacitor is strongly affected by the surface and structural properties of its electrode materials. Herein, we report a facile synthesis of high-performance supercapacitor electrode material based on CuS nano-hollow spheres with nanoporous structures, large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). This interesting electrode structure plays a key role in providing more active sites for electrochemical reactions, short ion and electron diffusion pathways and facilitated ion transport. The CuS nano-hollow spheres electrode exhibits excellent electrochemical performance including a maximum specific capacitance of 948 F g{sup −1} at 1 A g{sup −1}, significant rate capability of 46% capacitance retention at a high current density of 50 A g{sup −1}, and outstanding long-term cycling stability at various current densities. This work not only demonstrates the promising potential of the CuS-NHS electrodes for application in high-performance supercapacitors, but also sheds a new light on the metal sulfides design philosophy.

  15. Semiconductor-to-metallic flipping in a ZnFe2O4–graphene based smart nano-system: Temperature/microwave magneto-dielectric spectroscopy

    International Nuclear Information System (INIS)

    Ameer, Shahid; Gul, Iftikhar Hussain; Mahmood, Nasir; Mujahid, Muhammad

    2015-01-01

    Zn-(FeO 2 ) 2 –graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis with different percentages of graphene. The structure of the nanocomposite was confirmed through X-ray diffraction, micro-Raman scattering spectroscopy, Ultraviolet–Visible spectroscopy, and Fourier transform infrared spectroscopy. The structural growth and morphological aspects were analyzed using scanning/transmission electron microscopy, revealing marvelous micro-structural features of the assembled nano-system resembling a maple leaf. To determine the composition, energy dispersive spectroscopy and X-ray photoelectron spectroscopy were used. Microwave magneto-dielectric spectroscopy revealed the improved dielectric properties of the nano-composite compared to those of the parent functional nanocrystals. Temperature gradient dielectric spectroscopy was used over the spectral range from 100 Hz to 5 MHz to reveal the phenomenological effect that the nanosystem flips from its usual semiconductor nature to a metallic nature with sensing temperature. Electrical conductivity and dielectric analysis indicated that the dielectric loss and the dielectric permittivity increased at room temperature. This extraordinary switching capability of the functionalized graphene nanosystem opens up a new dimension for engineering advanced and efficient smart composite materials. - Graphical abstract: Display Omitted - Highlights: • Zn-(FeO 2 ) 2 –graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis. • The synthesized nano-system exhibits marvelous leaf like microstructure. • These nano-composites show improved magneto dielectric response. • This engineered smart nano-system shows phenomenological flipping from semiconductor like nature to metallic behavior

  16. Structural and dielectric studies on Ag doped nano ZnSnO3

    Science.gov (United States)

    Deepa, K.; Angel, S. Lilly; Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

    2018-04-01

    Undoped and Ag-doped nano Zinc Stannate (ZSO) ternary oxide were prepared by co-precipitation method. The crystallographic, morphological and optical properties of the synthesized nanoparticles were studied using X-ray diffraction (XRD) and UV-Visible spectroscopy (UV-Vis) and Scanning electron microscopy (SEM). The electrical properties of the synthesized samples were studied by dielectric measurements. Higher concentration Ag doped ZSO nanoparticles exhibit higher dielectric constant at low frequency.

  17. Elastic properties of porous low-k dielectric nano-films

    Science.gov (United States)

    Zhou, W.; Bailey, S.; Sooryakumar, R.; King, S.; Xu, G.; Mays, E.; Ege, C.; Bielefeld, J.

    2011-08-01

    Low-k dielectrics have predominantly replaced silicon dioxide as the interlayer dielectric for interconnects in state of the art integrated circuits. In order to further reduce interconnect RC delays, additional reductions in k for these low-k materials are being pursued via the introduction of controlled levels of porosity. The main challenge for such dielectrics is the substantial reduction in elastic properties that accompanies the increased pore volume. We report on Brillouin light scattering measurements used to determine the elastic properties of these films at thicknesses well below 200 nm, which are pertinent to their introduction into present ultralarge scale integrated technology. The observation of longitudinal and transverse standing wave acoustic resonances and their transformation into traveling waves with finite in-plane wave vectors provides for a direct non-destructive measure of the principal elastic constants that characterize the elastic properties of these porous nano-scale films. The mode dispersion further confirms that for porosity levels of up to 25%, the reduction in the dielectric constant does not result in severe degradation in the Young's modulus and Poisson's ratio of the films.

  18. Integrated lithography to prepare periodic arrays of nano-objects

    International Nuclear Information System (INIS)

    Sipos, Áron; Szalai, Anikó; Csete, Mária

    2013-01-01

    We present an integrated lithography method to prepare versatile nano-objects with variable shape and nano-scaled substructure, in wavelength-scaled periodic arrays with arbitrary symmetry. The idea is to illuminate colloid sphere monolayers by polarized beams possessing periodic lateral intensity modulations. Finite element method was applied to determine the effects of the wavelength, polarization and angle of incidence of the incoming beam, and to predict the characteristics of nano-objects, which can be fabricated on thin metal layer covered substrates due to the near-field enhancement under silica colloid spheres. The inter-object distance is controlled by varying the relative orientation of the periodic intensity modulation with respect to the silica colloid sphere monolayer. It is shown that illuminating silica colloid sphere monolayers by two interfering beams, linear patterns made of elliptical holes appear in case of linear polarization, while circularly polarized beams result in co-existent rounded objects, as more circular nano-holes and nano-crescents. The size of the nano-objects and their sub-structure is determined by the spheres diameter and by the wavelength. We present various complex plasmonic patterns made of versatile nano-objects that can be uniquely fabricated applying the inherent symmetry breaking possibilities in the integrated lithography method.

  19. Dielectric relaxation of glass particles with conductive nano-coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Shahid [Applied Technologies Department, QinetiQ Limited, Cody Technology Park, Farnborough, Hampshire, GU14 0LX (United Kingdom)

    2009-03-21

    This research focuses on the dielectric properties of particles consisting of glass cores with nanometre conductive coatings. The effects of the core glass particle shape (sphere, flake and fibre) and size are investigated for different coating characteristics over the frequency range 0.5-18 GHz. Experimental results for the coated glass particle combinations show the existence of a dielectric loss peak. This feature is associated with interfacial relaxation between the insulating core glass particle and the nanoscale conductive coating. The relaxation mechanism provides enhanced loss that is not observed in conventional solid metal particle composites. The results are fitted to a model, which shows that the relaxation frequency increases with increasing coating conductivity and thickness, with additional parameters identified for further particle optimizations.

  20. Porous sheet-like and sphere-like nano-architectures of SnO2 nanoparticles via a solvent-thermal approach and their gas-sensing performances

    International Nuclear Information System (INIS)

    Jie Liu; Tang, Xin-Cun; Xiao, Yuan-Hua; Hai Jia,; Gong, Mei-Li; Huang, Fu-Qin

    2013-01-01

    Highlights: • Porous sheet-like and sphere-like nano-architectures of SnO 2 nanoparticles have been prepared. • A solvent-thermal approach without surfactant or polymer templates simply by changing the volume ratio of DMF to water. • The formation mechanism of nano-architectures is proposed in this article. • Porous sphere-like SnO 2 nano-architectures exhibit good sensitivity to the reduce vapors tested. • Sheet-like materials show better selectivity to ethanol. -- Abstract: Porous sheet-like and sphere-like nano-architectures of SnO 2 nanoparticles have been prepared via a solvent-thermal approach in the absence of any surfactant or polymer templates by simply changing the volume ratio of DMF to water. The nano-materials have been characterized by FESEM, XRD, IR, TEM and BET. A mechanism for the formation of nano-architectures is also proposed based on the assembly behaviors of DMF in water. The gas sensors constructed with porous sphere-like SnO 2 nano-architectures exhibit much higher sensitivity to the reduce vapors tested, compared to those from porous sheet-like SnO 2 materials, while the sheet-like materials show better selectivity to ethanol. The nano-architectures fabricated with the facile method are promising candidates for building chemical sensors with tunable performances

  1. Vavilov-Cherenkov and transition radiations on the dielectric and metallic spheres

    International Nuclear Information System (INIS)

    Afanasiev, G.N.; Kartavenko, V.G.; Stepanovsky, Yu.P.

    2003-01-01

    Closed expressions are obtained for angular and frequency radiation intensities produced by a charge moving inside the dielectric sphere S, with observations made outside S (in fact, this is a typical experimental situation when a charge moves in one medium while measurements are made in the other one). It is shown that the difference in media properties inside and outside S drastically affects angular and frequency distributions. Also, a charge motion is considered which begins and terminates in medium 2 and which passes either through the dielectric sphere filled with medium 1 or through the metallic one. The energy flux in medium 2 involves the Vavilov-Cherenkov, transition radiation and the one arising from the charge instantaneous beginning and termination of motion. The evaluated angular and frequency distributions for various charge velocities and medium properties inside and outside S show that the standard identification of the charge velocity by its radiation on the part of the charge trajectory where βn>1 is not always valid. We analyze also the frequently used interpretation of the transition radiation in terms of instantaneous charge deceleration in one medium and its sudden acceleration in another one, and find them as to be insufficient. On the other hand, attempts to interpret the transition radiation in terms of semi-infinite motions terminating in one medium and beginning in the other one turn out to be correct if one takes into account the terms corresponding to the Vavilov-Cherenkov radiation

  2. Flat-on ambipolar triphenylamine/C60 nano-stacks formed from the self-organization of a pyramid-sphere-shaped amphiphile.

    Science.gov (United States)

    Liang, Wei-Wei; Huang, Chi-Feng; Wu, Kuan-Yi; Wu, San-Lien; Chang, Shu-Ting; Cheng, Yen-Ju; Wang, Chien-Lung

    2016-04-21

    A giant amphiphile, which is constructed with an amorphous nano-pyramid (triphenylamine, TPA) and a crystalline nano-sphere (C 60 ), was synthesized. Structural characterization indicates that this pyramid-sphere-shaped amphiphile ( TPA-C 60 ) forms a solvent-induced ordered phase, in which the two constituent units self-assemble into alternating stacks of two-dimensional (2D) TPA and C 60 nano-sheets. Due to the complexity of the molecular structure and the amorphous nature of the nano-pyramid, phase formation was driven by intermolecular C 60 -C 60 interactions and the ordered phase could not be reformed from the TPA-C 60 melt. Oriented crystal arrays of TPA-C 60 , which contain flat-on TPA/C 60 nano-stacks, can be obtained via a PDMS-assisted crystallization (PAC) technique. The flat-on dual-channel supramolecular structure of TPA-C 60 delivered ambipolar and balanced charge-transport characteristics with an average μ e of 2.11 × 10 -4 cm 2 V -1 s -1 and μ h of 3.37 × 10 -4 cm 2 V -1 s -1 . The anisotropic charge-transport ability of the pyramid-sphere-shaped amphiphile was further understood based on the lattice structure and the lattice orientation of TPA-C 60 revealed from electron diffraction analyses.

  3. Semiconductor-to-metallic flipping in a ZnFe{sub 2}O{sub 4}–graphene based smart nano-system: Temperature/microwave magneto-dielectric spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ameer, Shahid, E-mail: shahidameer@scme.nust.edu.pk [School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Gul, Iftikhar Hussain [School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Mahmood, Nasir [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Mujahid, Muhammad [School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan)

    2015-01-15

    Zn-(FeO{sub 2}){sub 2}–graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis with different percentages of graphene. The structure of the nanocomposite was confirmed through X-ray diffraction, micro-Raman scattering spectroscopy, Ultraviolet–Visible spectroscopy, and Fourier transform infrared spectroscopy. The structural growth and morphological aspects were analyzed using scanning/transmission electron microscopy, revealing marvelous micro-structural features of the assembled nano-system resembling a maple leaf. To determine the composition, energy dispersive spectroscopy and X-ray photoelectron spectroscopy were used. Microwave magneto-dielectric spectroscopy revealed the improved dielectric properties of the nano-composite compared to those of the parent functional nanocrystals. Temperature gradient dielectric spectroscopy was used over the spectral range from 100 Hz to 5 MHz to reveal the phenomenological effect that the nanosystem flips from its usual semiconductor nature to a metallic nature with sensing temperature. Electrical conductivity and dielectric analysis indicated that the dielectric loss and the dielectric permittivity increased at room temperature. This extraordinary switching capability of the functionalized graphene nanosystem opens up a new dimension for engineering advanced and efficient smart composite materials. - Graphical abstract: Display Omitted - Highlights: • Zn-(FeO{sub 2}){sub 2}–graphene smart nano-composites were synthesized using a novel modified solvothermal synthesis. • The synthesized nano-system exhibits marvelous leaf like microstructure. • These nano-composites show improved magneto dielectric response. • This engineered smart nano-system shows phenomenological flipping from semiconductor like nature to metallic behavior.

  4. Subcooled film boiling heat transfer on a high temperature sphere in very dilute Al2O3 nano-fluids

    International Nuclear Information System (INIS)

    Hyun Sun Park; Dereje Shiferaw; Bal Raj Sehgal

    2005-01-01

    found in similar experiments with distilled water. The experiments have also shown that if some nano-particles stick to the surface of the hot sphere (in the event that the surface is not washed in-between the experiments), film boiling practically disappears and the quench proceeds very rapidly. In this study, a series of quenching experiments with a high temperature sphere in subcooled Al 2 O 3 nano-fluids with the very dilute concentrations of 0.01 to 0.05 g/liter are conducted to investigate the characteristics of film boiling and compare to those in pure water tests. One stainless steel sphere of 10 mm in diameter is heated to the initial sphere temperature up to 1100 K in the induction furnace and plunged by a pneumatic actuator into a pool of the dilute nano-fluid at the liquid subcooling of about 20 K by a pneumatic actuator. The transient center temperature is continually recorded and monitored with a data acquisition system. The center temperature data is analyzed to obtain sphere wall heat fluxes and the corresponding heat transfer coefficients. The test results are carefully compared with our previous experimental results for nano-fluids with the higher concentrations of nano-particles in water. (authors)

  5. Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 39; Issue 1. Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel auto-combustion technique. Mamata Maisnam Nandeibam Nilima Maisnam Victory Sumitra Phanjoubam. Volume 39 Issue 1 February 2016 ...

  6. Employing Ti nano-powder dielectric to enhance surface characteristics in electrical discharge machining of AISI D2 steel

    Energy Technology Data Exchange (ETDEWEB)

    Marashi, Houriyeh, E-mail: houriyeh@marashi.co [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Center of Advanced Manufacturing and Materials Processing (AMMP), 50603 Kuala Lumpur (Malaysia); Sarhan, Ahmed A.D., E-mail: ah_sarhan@yahoo.com [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Center of Advanced Manufacturing and Materials Processing (AMMP), 50603 Kuala Lumpur (Malaysia); Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516 (Egypt); Hamdi, Mohd [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Center of Advanced Manufacturing and Materials Processing (AMMP), 50603 Kuala Lumpur (Malaysia)

    2015-12-01

    Graphical abstract: - Highlights: • We proposed adding Ti nano-powder to dielectric in EDM. • Average and peak-valley surface roughness was improved by 35 and 40%, respectively. • Improvement of up to 69% in material removal rate was obtained. • Enhanced surface morphology and formation of shallower craters were observed. - Abstract: Manufacturing components with superior surface characteristics is challenging when electrical discharge machining (EDM) is employed for mass production. The aim of this research is to enhance the characteristics of AISI D2 steel surface machined with EDM through adding Ti nano-powder to dielectric under various machining parameters, including discharge duration (T{sub on}) and peak current (I). Surface roughness profilometer, FESEM and AFM analysis were utilized to reveal the machined surface characteristics in terms of surface roughness, surface morphology and surface micro-defects. Moreover, EDX analysis was performed in order to evaluate the atomic deposition of Ti nano-powder on the surface. The concentration of Ti nano-powder in dielectric was also examined using ESEM and EDX. According to the results, the addition of Ti nano-powder to dielectric notably enhanced the surface morphology and surface roughness at all machining parameters except T{sub on} = 340 μs. Of these parameters, maximum enhancement was observed at T{sub on} = 210 μs, where the material removal rate and average surface roughness improved by ∼69 and ∼35% for peak current of 6 and 12 A, respectively. Elemental analysis signified negligible Ti deposition on the machined surface while the atomic concentration of Ti was increased around the crack areas.

  7. Lithium-doped hydroxyapatite nano-composites: Synthesis, characterization, gamma attenuation coefficient and dielectric properties

    Science.gov (United States)

    Badran, H.; Yahia, I. S.; Hamdy, Mohamed S.; Awwad, N. S.

    2017-01-01

    Lithium-hydroxyapatite (0, 1, 5, 10, 20, 30 and 40 wt% Li-HAp) nano-composites were synthesized by sol-gel technique followed by microwave-hydrothermal treatment. The composites were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and Raman techniques. Gamma attenuation coefficient and the dielectric properties for all composites were investigated. The crystallinity degree of Li-doped HAp was higher than that of un-doped HAp. Gamma attenuation coefficient values increased from 0.562 cm-1 for 0 wt% Li-HAp to 2.190 cm-1 for 40 wt% Li-HAp. The alternating current conductivity increased with increasing frequency. The concentration of Li affect the values of dielectric constant where Li doped HAp of low dielectric constant can have an advantage for healing in bone fractures. The calcium to phosphorus ratio decreased from 1.43 to 1.37 with the addition of lithium indicating the Ca deficiency in the studied composites. Our findings lead to the conclusion that Li-HAp is a new nano-composite useful for medical applications and could be doped with gamma shield materials.

  8. Significantly Elevated Dielectric and Energy Storage Traits in Boron Nitride Filled Polymer Nano-composites with Topological Structure

    Science.gov (United States)

    Feng, Yefeng; Zhang, Jianxiong; Hu, Jianbing; Li, Shichun; Peng, Cheng

    2018-03-01

    Interface induced polarization has a prominent influence on dielectric properties of 0-3 type polymer based composites containing Si-based semi-conductors. The disadvantages of composites were higher dielectric loss, lower breakdown strength and energy storage density, although higher permittivity was achieved. In this work, dielectric, conductive, breakdown and energy storage properties of four nano-composites have been researched. Based on the cooperation of fluoropolymer/alpha-SiC layer and fluoropolymer/hexagonal-BN layer, it was confirmed constructing the heterogeneous layer-by-layer composite structure rather than homogeneous mono-layer structure could significantly reduce dielectric loss, promote breakdown strength and increase energy storage density. The former worked for a larger dielectric response and the latter layer acted as a robust barrier of charge carrier transfer. The best nano-composite could possess a permittivity of 43@100 Hz ( 3.3 times of polymer), loss of 0.07@100 Hz ( 37% of polymer), discharged energy density of 2.23 J/cm3@249 kV/cm ( 10 times of polymer) and discharged energy efficiency of 54%@249 kV/cm ( 5 times of polymer). This work might enlighten a facile route to achieve the promising high energy storage composite dielectrics by constructing the layer-by-layer topological structure.

  9. The fabrication of a carbon nanotube array using a catalyst-poisoning layer in the inverse nano-sphere lithography method

    International Nuclear Information System (INIS)

    Tsai, Tsung-Yen; Chen, Tsung-Han; Tai, Nyan-Hwa; Chang, Shih-Chin; Hsu, Hui-Chen; Joseph Palathinkal, Thomas

    2009-01-01

    A new method for the fabrication of periodic CNT arrays was developed in this study, which involves the use of the inverse nano-sphere lithography (INSL) process. Mo of a honeycomb pattern, acting as a catalyst-poisoning layer, was produced by the nano-sphere lithography (NSL) process; the Mo poisoned the catalyst and prevented CNT growth where deposited, and as a result, a periodic CNT pattern was obtained. Using this method, the uniformity of the CNT array can be improved by preventing the negative effect of arrangement defects in self-assembled monolayers. The size and the period of the CNT array can be adjusted by careful selection of the polystyrene (PS) sphere diameter. X-ray photoelectron spectroscope (XPS) analysis revealed that the Co catalyst was ineffective on the areas of Mo deposition due to the diffusion of Co into the Mo layer.

  10. The fabrication of a carbon nanotube array using a catalyst-poisoning layer in the inverse nano-sphere lithography method

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Tsung-Yen; Chen, Tsung-Han; Tai, Nyan-Hwa; Chang, Shih-Chin; Hsu, Hui-Chen; Joseph Palathinkal, Thomas, E-mail: nhtai@mx.nthu.edu.t [Department of Materials Science and Engineering, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan (China)

    2009-07-29

    A new method for the fabrication of periodic CNT arrays was developed in this study, which involves the use of the inverse nano-sphere lithography (INSL) process. Mo of a honeycomb pattern, acting as a catalyst-poisoning layer, was produced by the nano-sphere lithography (NSL) process; the Mo poisoned the catalyst and prevented CNT growth where deposited, and as a result, a periodic CNT pattern was obtained. Using this method, the uniformity of the CNT array can be improved by preventing the negative effect of arrangement defects in self-assembled monolayers. The size and the period of the CNT array can be adjusted by careful selection of the polystyrene (PS) sphere diameter. X-ray photoelectron spectroscope (XPS) analysis revealed that the Co catalyst was ineffective on the areas of Mo deposition due to the diffusion of Co into the Mo layer.

  11. Nano-CMOS gate dielectric engineering

    CERN Document Server

    Wong, Hei

    2011-01-01

    According to Moore's Law, not only does the number of transistors in an integrated circuit double every two years, but transistor size also decreases at a predictable rate. At the rate we are going, the downsizing of CMOS transistors will reach the deca-nanometer scale by 2020. Accordingly, the gate dielectric thickness will be shrunk to less than half-nanometer oxide equivalent thickness (EOT) to maintain proper operation of the transistors, leaving high-k materials as the only viable solution for such small-scale EOT. This comprehensive, up-to-date text covering the physics, materials, devic

  12. Synthesis of nano grade hollow silica sphere via a soft template method.

    Science.gov (United States)

    Tsai, Ming-Shyong; Li, Miao Ju; Yen, Fu-Hsu

    2008-06-01

    The nano grade hollow silica sphere (HSS) was synthesized by a novel soft template method. We found that the precipitate of aluminate had a porous structure that could be the soft template for HSS. After mixing the colloidal silica with the aluminate precipitate, the bubble trapped in this porous structure could form the nano grade HSS. The aluminate precipitate was removed by adjusting the pH of the slurry to approximately 1. The outside diameter, the specific surface, and the mean pore size diameter of the forming HSS were 60-90 nm, 571 m2/g, and 3 nm, respectively. The formed HSS was collected by modifying the surface with Si(OCH3)3CHCH2 (VTMO) and then filtrating the precipitated gel in the n-butanol and ethanol solvent system.

  13. Reflection characterization of nano-sized dielectric structure in Morpho butterfly wings

    Science.gov (United States)

    Zhu, Dong

    2017-10-01

    Morpho butterflies living in Central and South America are well-known for their structural-colored blue wings. The blue coloring originates from the interaction of light with nano-sized dielectric structures that are equipped on the external surface of scales covering over their wings. The high-accuracy nonstandard finite-difference time domain (NS-FDTD) method is used to investigate the reflection characterization from the nanostructures. In the NS-FDTD calculation, a computational model is built to mimic the actual tree-like multilayered structures wherever possible using the hyperbolic tangent functions. It is generally known that both multilayer interference and diffraction grating phenomena can occur when light enters the nano-sized multilayered structure. To answer the question that which phenomenon is mainly responsible for the blue coloring, the NS-FDTD calculation is performed under various incidence angles at wavelengths from 360 to 500 nm. The calculated results at one incident wavelength under different incidence angles are visualized in a two-dimensional mapping image, where horizontal and vertical axes are incidence and reflection angles, respectively. The images demonstrate a remarkable transition from a ring-like pattern at shorter wavelengths to a retro-reflection pattern at longer wavelengths. To clarify the origin of the pattern transition, the model is separated into several simpler parts and compared their mapping images with the theoretical diffraction calculations. It can be concluded that the blue coloring at longer wavelengths is mainly caused by the cooperation of multilayer interference and retro-reflection while the effect of diffraction grating is predominant at shorter wavelengths.

  14. Construct 3D porous hollow Co3O4 micro-sphere: A potential oxidizer of nano-energetic materials with superior reactivity

    Science.gov (United States)

    Wang, Jun; Zheng, Bo; Qiao, Zhiqiang; Chen, Jin; Zhang, Liyuan; Zhang, Long; Li, Zhaoqian; Zhang, Xingquan; Yang, Guangcheng

    2018-06-01

    High energy density and rapid reactivity are the future trend for nano-energetic materials. Energetic performance of nano-energetic materials depends on the interfacial diffusion and mass transfer during the reacted process. However, the development of desired structure to significantly enhance reactivity still remains challenging. Here we focused on the design and preparation of 3D porous hollow Co3O4 micro-spheres, in which gas-blowing agents (air) and maximize interfacial interactions were introduced to enhance mass transport and reduce the diffusion distance between the oxidizer and fuel (Aluminum). The 3D hierarchical Co3O4/Al based nano-energetic materials show a low-onset decomposition temperature (423 °C), and high heat output (3118 J g-1) resulting from porous and hollow nano-structure of Co3O4 micro-spheres. Furthermore, 3D hierarchical Co3O4/Al arrays were directly fabricated on the silicon substrate, which was fully compatible with silicon-based microelectromechanical systems to achieve functional nanoenergetics-on-a-chip. This approach provides a simple and efficient way to fabricate 3D ordered nano-energetic arrays with superior reactivity and the potential on the application in micro-energetic devices.

  15. Effect of dielectric medium on the nonclassical properties of nonlinear sphere coherent states

    Directory of Open Access Journals (Sweden)

    E Amooghorban

    2014-04-01

    Full Text Available In order to investigate the effect of a medium with dissipation and dispersion and also the curvature of the physical space on the properties of the incident quantum states, we use the quantization of electromagnetic field based on phenomenological approach to obtain input-output relations between radiations on both sides of dielectric slab. By using these relations the fidelity, the Wigner function, and also the quantum correlation of the outgoing state through dielectric slab are obtained for a situation in which the rightward incident state is a nonlinear coherent state on a sphere and the leftward incident state is a vacuum state. Here, the incident states are considered monochromatic and the modeling of the medium is given by the Lorentz' model. Accordingly, we study nonclassical properties of the output states such as the quantum entanglement. It will be observed that the nonclassical properties of the outgoing states depend strongly on the optical property of the medium and also on the curvature of the physical state.

  16. Dielectric relaxation and ac conduction in γ-irradiated UHMWPE/MWCNTs nano composites: Impedance spectroscopy analysis

    International Nuclear Information System (INIS)

    Maqbool, Syed Asad; Mehmood, Malik Sajjad; Mukhtar, Saqlain Saqib; Baluch, Mansoor A.; Khan, Shamim; Yasin, Tariq; Khan, Yaqoob

    2017-01-01

    The dielectric behavior of γ-irradiated ultra-high molecular weight polyethylene (UHMWPE) and its nano composites (NCs) with γ-ray modified multi wall carbon nano tubes (γ-MWCNTs) and MWCNTs had been studied using impedance spectroscopy. The study had been carried out in the frequency range of 20–2 MHz at room temperature. All samples (pure and NCs) were prepared in the form of sheets and irradiated with γ-dose of 50 kGy and 100 kGy, respectively. The comprehensive analysis of results revealed that resistivity of UHMWPE for conduction decreased on irradiation and incorporation of MWCNTs (whether γ ray modified or un-modified) due to the radiation induced damage and conductive networks induced by MWCNTs. At low frequency range a significant increase in the dielectric constant had been observed because of irradiation and addition of MWNCTs. The trend of loss tangent and ac conductivity for each investigated sample depended on resistivity offered and had a decreasing trend as a function of frequency. Moreover, dissipation factor increased with the incorporation of MWNCTs and irradiation from 0.12 to 0.22. In addition to this, non-frequency dependent static dielectric constant was also found to increase with irradiation and incorporation of MWCNTs. The relaxation time was found to increase from 1.2 to 4.3 ms due to hindrance offered by radiation induced mutual cross linking of PE chains and polymer-MWNCTs bindings. - Highlights: • The resistivity for conduction in pristine UHMWPE is decreased with γ-irradiation. • Conduction in PE/MWCNTs nanocomposites increased due to MWCNTs addition. • Static dielectric constant of UHMWPE increased with γ-irradiation. • Static dielectric constant of UHMWPE increased due to MWCNTs incorporation.

  17. A comparative study of nano-SiO2 and nano-TiO2 fillers on proton conductivity and dielectric response of a silicotungstic acid-H3PO4-poly(vinyl alcohol) polymer electrolyte.

    Science.gov (United States)

    Gao, Han; Lian, Keryn

    2014-01-08

    The effects of nano-SiO2 and nano-TiO2 fillers on a thin film silicotungstic acid (SiWA)-H3PO4-poly(vinyl alcohol) (PVA) proton conducting polymer electrolyte were studied and compared with respect to their proton conductivity, environmental stability, and dielectric properties, across a temperature range from 243 to 323 K. Three major effects of these fillers have been identified: (a) barrier effect; (b) intrinsic dielectric constant effect; and (c) water retention effect. Dielectric analyses were used to differentiate these effects on polymer electrolyte-enabled capacitors. Capacitor performance was correlated to electrolyte properties through dielectric constant and dielectric loss spectra. Using a single-ion approach, proton density and proton mobility of each polymer electrolyte were derived as a function of temperature. The results allow us to deconvolute the different contributions to proton conductivity in SiWA-H3PO4-PVA-based electrolytes, especially in terms of the effects of fillers on the dynamic equilibrium of free protons and protonated water in the electrolytes.

  18. Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts.

    Science.gov (United States)

    Machoke, Albert Gonche Fortunatus; Apeleo Zubiri, Benjamin; Leonhardt, Rainer; Marthala, Venkata Ramana Reddy; Schmiele, Martin; Unruh, Tobias; Hartmann, Martin; Spiecker, Erdman; Schwieger, Wilhelm

    2017-08-16

    Nanosized materials are expected to play a unique role in the development of future catalytic processes. Herein, pre-prepared and geometrically well-defined amorphous silica spheres are densified into silica-rich zeolites with nanosized dimensions. After the densification, the obtained nanosized zeolites exhibit the same spherical morphology like the starting precursor but characterized by a drastically reduced size, higher density, and high crystallinity. The phase transformation into crystalline zeolite material and the densification effect are achieved through a well-controlled steam-assisted treatment of the larger precursor particles so that the transformation process proceeds always towards the center of the spheres, just like a shrinking process. Furthermore, this procedure is applicable also to commercially available silica particles, as well as aluminum-containing systems (precursors) leading to acidic nano-catalysts with improved catalytic performance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Electrical properties of nano-resistors made from the Zr-doped HfO2 high-k dielectric film

    Science.gov (United States)

    Zhang, Shumao; Kuo, Yue

    2018-03-01

    Electrical properties of nano-sized resistors made from the breakdown of the metal-oxide-semiconductor capacitor composed of the amorphous high-k gate dielectric have been investigated under different stress voltages and temperatures. The effective resistance of nano-resistors in the device was estimated from the I-V curve in the high voltage range. It decreased with the increase of the number of resistors. The resistance showed complicated temperature dependence, i.e. it neither behaves like a conductor nor a semiconductor. In the low voltage operation range, the charge transfer was controlled by the Schottky barrier at the nano-resistor/Si interface. The barrier height decreased with the increase of stress voltage, which was probably caused by the change of the nano-resistor composition. Separately, it was observed that the barrier height was dependent on the temperature, which was probably due to the dynamic nano-resistor formation process and the inhomogeneous barrier height distribution. The unique electrical characteristics of this new type of nano-resistors are important for many electronic and optoelectronic applications.

  20. Tailored synthesis of monodispersed nano/submicron porous silicon oxycarbide (SiOC) spheres with improved Li-storage performance as an anode material for Li-ion batteries

    Science.gov (United States)

    Shi, Huimin; Yuan, Anbao; Xu, Jiaqiang

    2017-10-01

    A spherical silicon oxycarbide (SiOC) material (monodispersed nano/submicron porous SiOC spheres) is successfully synthesized via a specially designed synthetic strategy involving pyrolysis of phenyltriethoxysilane derived pre-ceramic polymer spheres at 900 °C. In order to prevent sintering of the pre-ceramic polymer spheres upon heating, a given amount of hollow porous SiO2 nanobelts which are separately prepared from tetraethyl orthosilicate with CuO nanobelts as templates are introduced into the pre-ceramic polymer spheres before pyrolysis. This material is investigated as an anode for lithium-ion batteries in comparison with the large-size bulk SiOC material synthesized under the similar conditions but without hollow SiO2 nanobelts. The maximum reversible specific capacity of ca. 900 mAh g-1 is delivered at the current density of 100 mA g-1 and ca. 98% of the initial capacity is remained after 100 cycles at 100 mA g-1 for the SiOC spheres material, which are much superior to the bulk SiOC material. The improved lithium storage performance in terms of specific capacity and cyclability is attributed to its particular morphology of monodisperse nano/submicron porous spheres as well as its modified composition and microstructure. This SiOC material has higher Li-storage activity and better stability against volume expansion during repeated lithiation and delithiation cycling.

  1. Fabrication of a Au–polystyrene sphere substrate with three-dimensional nanofeatures for surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Hu, Xiaotang; Xu, Zongwei; Li, Kang; Fang, Fengzhou; Wang, Liyang

    2015-01-01

    Graphical abstract: Methods for fabricating three-dimensional nanofeature arrays for surface-enhanced Raman spectroscopy (SERS) substrates were explored by combining the self-assembly of nanoscale polystyrene (PS) spheres with subsequent Au film ion sputter coating modulation. The substrate's nanoscale hot-spot features were controlled using the Au coating film thickness regulation and focused ion beam (FIB) nano-patterning regulation methods. Scanning electron microscopy and Raman spectroscopy were employed to analyze the substrate morphology and the enhancement mechanism of the three-dimensional SERS substrate. PS microspheres with diameters of 151 nm and 360 nm were coated with Au layers of different thicknesses ranging from 10 nm to 270 nm. The configuration of the Au–PS spheres can be regulated to hexagonal close packing with nanoscale V-shaped slits with a 10 to 20 nm gap pattern. Nanoscale Au particles and clusters with a clear outline covered the surface of the PS spheres, in which the multiple-scale structures increase the specific surface area of the SERS-active substrate. Nanoscale cracks formed on the smaller Au–PS spheres with a diameter of 151 nm, which also exhibited strong SERS activity. The substrate surface temperature regularly increased after Au coating, and the thermal expansion coefficient difference and PS glass transition properties were studied to explain the Au–PS spheres nanofeature configuration development. The fabricated Au–PS spheres SERS feature is a type of three-dimensional and highly ordered array, which can show Raman scattering characteristics by providing a SERS enhancement factor of greater than 107. - Highlights: • Au film coating over PS nanospheres was studied to develop 3D SERS substrate. • The Au–PS sphere can be hexagonal close packing with 10–20 nm nanoscale gaps. • PS glass transition property results in Au–PS sphere nano configuration evolution. • The nanoscale Au clusters with clear outline were

  2. Fabrication of a Au–polystyrene sphere substrate with three-dimensional nanofeatures for surface-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiaotang; Xu, Zongwei, E-mail: zongweixu@163.com; Li, Kang; Fang, Fengzhou, E-mail: fzfang@tju.edu.cn; Wang, Liyang

    2015-11-15

    Graphical abstract: Methods for fabricating three-dimensional nanofeature arrays for surface-enhanced Raman spectroscopy (SERS) substrates were explored by combining the self-assembly of nanoscale polystyrene (PS) spheres with subsequent Au film ion sputter coating modulation. The substrate's nanoscale hot-spot features were controlled using the Au coating film thickness regulation and focused ion beam (FIB) nano-patterning regulation methods. Scanning electron microscopy and Raman spectroscopy were employed to analyze the substrate morphology and the enhancement mechanism of the three-dimensional SERS substrate. PS microspheres with diameters of 151 nm and 360 nm were coated with Au layers of different thicknesses ranging from 10 nm to 270 nm. The configuration of the Au–PS spheres can be regulated to hexagonal close packing with nanoscale V-shaped slits with a 10 to 20 nm gap pattern. Nanoscale Au particles and clusters with a clear outline covered the surface of the PS spheres, in which the multiple-scale structures increase the specific surface area of the SERS-active substrate. Nanoscale cracks formed on the smaller Au–PS spheres with a diameter of 151 nm, which also exhibited strong SERS activity. The substrate surface temperature regularly increased after Au coating, and the thermal expansion coefficient difference and PS glass transition properties were studied to explain the Au–PS spheres nanofeature configuration development. The fabricated Au–PS spheres SERS feature is a type of three-dimensional and highly ordered array, which can show Raman scattering characteristics by providing a SERS enhancement factor of greater than 107. - Highlights: • Au film coating over PS nanospheres was studied to develop 3D SERS substrate. • The Au–PS sphere can be hexagonal close packing with 10–20 nm nanoscale gaps. • PS glass transition property results in Au–PS sphere nano configuration evolution. • The nanoscale Au clusters with clear outline

  3. Nano-micro carbon spheres anchored on porous carbon derived from dual-biomass as high rate performance supercapacitor electrodes

    Science.gov (United States)

    Liu, Shaobo; Zhao, Yang; Zhang, Baihui; Xia, Hui; Zhou, Jianfei; Xie, Wenke; Li, Hongjian

    2018-03-01

    Hierarchical nano-micro carbon spheres@rice straw-derived porous carbon composites are successfully synthesized by the in situ decoration of the porous carbon with carbon spheres from glucose under the assistance of cetyltrimethyl ammonium bromide micelles and further activated by KOH. The scanning electron microscope images clearly show the carbon spheres disperse homogeneously and orderly onto the surface and in the inner macropores of the porous carbon. The diameter of the carbon spheres varies from 475 nm to 1.6 μm, which can be easily controlled by introducing extra inducing agent. The optimal composites exhibit a large specific surface area (1122 m2 g-1), rich content of oxygen (14.2 wt %), and tunable hierarchical porous structure. When used as supercapacitor electrodes, the novel composites with abundant fruits present a high specific capacitance of 337 F g-1 at 1 A g-1, excellent rate retention of 83% from 1 to 20 A g-1 and a good cycling stability with 96% capacitance retention after 10000 cycles. In this strategy, the thought of shared ion-buffering reservoirs is proposed and the mutual promotion effects between the carbon spheres and porous carbon in the composites are also practically demonstrated to contribute the enhanced electrochemical performances.

  4. Application of semiclassical and geometrical optics theories to resonant modes of a coated sphere.

    Science.gov (United States)

    Bambino, Túlio M; Breitschaft, Ana Maria S; Barbosa, Valmar C; Guimarães, Luiz G

    2003-03-01

    This work deals with some aspects of the resonant scattering of electromagnetic waves by a metallic sphere covered by a dielectric layer, in the weak-absorption approximation. We carry out a geometrical optics treatment of the scattering and develop semiclassical formulas to determine the positions and widths of the system resonances. In addition, we show that the mean lifetime of broad resonances is strongly dependent on the polarization of the incident light.

  5. Plasmonic nano-sensor based on metal-dielectric-metal waveguide with the octagonal cavity ring

    Science.gov (United States)

    Ghorbani, Saeed; Dashti, Mohammad Ali; Jabbari, Masoud

    2018-06-01

    In this paper, a refractive index plasmonic sensor including a waveguide of metal–insulator–metal with side coupled octagonal cavity ring has been suggested. The sensory and transmission feature of the structure has been analyzed numerically using Finite Element Method numerical solution. The effect of coupling distance and changing the width of metal–insulator–metal waveguide and refractive index of the dielectric located inside octagonal cavity—which are the effective factors in determining the sensory feature—have been examined so completely that the results of the numerical simulation show a linear relation between the resonance wavelength and refractive index of the liquid/gas dielectric material inside the octagonal cavity ring. High sensitivity of the sensor in the resonance wavelength, simplicity and a compact geometry are the advantages of the refractive plasmonic sensor advised which make that possible to use it for designing high performance nano-sensor and bio-sensing devices.

  6. Numerical Study on Alternating Current Breakdown Mechanism Between Sphere-Sphere Electrodes in Transformer Oil-Based Magnetic Nanofluids.

    Science.gov (United States)

    Lee, Won-Ho; Lee, Jong-Chul

    2018-09-01

    A numerical simulation was developed for magnetic nanoparticles in a liquid dielectric to investigate the AC breakdown voltage of the magnetic nanofluids according to the volume concentration of the magnetic nanoparticles. In prior research, we found that the dielectric breakdown voltage of the transformer oil-based magnetic nanofluids was positively or negatively affected according to the amount of magnetic nanoparticles under a testing condition of dielectric fluids, and the trajectory of the magnetic nanoparticles in a fabricated chip was visualized to verify the related phenomena via measurements and computations. In this study, a numerical simulation of magnetic nanoparticles in an insulating fluid was developed to model particle tracing for AC breakdown mechanisms happened to a sphere-sphere electrode configuration and to propose a possible mechanism regarding the change in the breakdown strength due to the behavior of the magnetic nanoparticles with different applied voltages.

  7. Electrostatic field in inhomogeneous dielectric media. I. Indirect boundary element method

    International Nuclear Information System (INIS)

    Goel, N.S.; Gang, F.; Ko, Z.

    1995-01-01

    A computationally fast method is presented for calculating electrostatic field in arbitrary inhomogeneous dielectric media with open boundary condition. The method involves dividing the whole space into cubical cells and then finding effective dielectric parameters for interfacial cells consisting of several dielectrics. The electrostatic problem is then solved using either the indirect boundary element method described in this paper or the so-called volume element method described in the companion paper. Both methods are tested for accuracy by comparing the numerically calculated electrostatic fields against those analytically obtained for a dielectric sphere and dielectric ellipsoid in a uniform field and for a dielectric sphere in a point charge field

  8. Structural, spectral, dielectric and magnetic properties of Tb–Dy doped Li-Ni nano-ferrites synthesized via micro-emulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid.malik95@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz; Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of scientific research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-01

    Terbium (Tb) and dysprosium (Dy) doped lithium-nickel nano-sized ferrites (Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2−x}O{sub 4} where x=0.00−0.08) were prepared by micro-emulsion technique. The X-ray diffraction (XRD) patterns confirmed the single phase cubic spinel structure. The lattice constant was increased due to larger ionic radii of Tb{sup 3+} and Dy{sup 3+} cations. The crystallite size was found in the range 30–42 nm. The FTIR (Fourier transform infrared spectroscopy) spectra revealed two significant absorption bands (~400–600 cm{sup −1}) which indicate the formation of cubic spinel structure. The peaking behavior of dielectric parameters was observed beyond 1.5 GHz. The dielectric constant and dielectric loss were found to decrease by the increase of Tb–Dy contents and frequency. The doping of Tb and Dy in Li–Ni ferrites led to increase the coercive field (120–156 Oe). The smaller magnetic and dielectric parameters suggested the possible utility of these nano-materials in switching and microwave devices applications. - Highlights: • Li{sub 0.2}Ni{sub 0.8}Tb{sub 0.5x}Dy{sub 0.5x}Fe{sub 2-x}O{sub 4} ferrites were synthesized by micro-emulsion route. • Tb and Dy addition improves coercivity while decreased saturation magnetization. • These nanomaterials can be useful in microwave and switching devices applications.

  9. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

    2017-03-15

    Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

  10. Dielectric strength of voidless BaTiO{sub 3} films with nano-scale grains fabricated by aerosol deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Ki; Lee, Young-Hie, E-mail: yhlee@kw.ac.kr [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); Lee, Seung-Hwan [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); In Kim, Soo; Woo Lee, Chang [Department of Nano and Electronic Physics, Kookmin University, Seoul (Korea, Republic of); Rag Yoon, Jung [R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); Lee, Sung-Gap [Department of Ceramic Engineering, Engineering Research Institute, Gyeongsang National University, Jinju (Korea, Republic of)

    2014-01-07

    In order to investigate the dielectric strength properties of the BaTiO{sub 3} films with nano-scale grains with uniform grain size and no voids, BaTiO{sub 3} films were fabricated with a thickness of 1 μm by an AD process, and the fabricated films were sintered at 800, 900, and 1000 °C in air and reducing atmosphere. The films have superior dielectric strength properties due to their uniform grain size and high density without any voids. In addition, based on investigation of the leakage current (intrinsic) properties, it was confirmed that the sintering conditions of the reducing atmosphere largely increase leakage currents due to generated electrons and doubly ionized oxygen vacancies following the Poole-Frenkel emission mechanism, and increased leakage currents flow at grain boundary regions. Therefore, we conclude that the extrinsic breakdown factors should be eliminated for superior dielectric strength properties, and it is important to enhance grain boundaries by doping acceptors and rare-earth elements.

  11. Mastering VMware vSphere 5

    CERN Document Server

    Lowe, Scott

    2011-01-01

    A new and updated edition of bestselling Mastering VMware vSphere 4 Written by leading VMware expert, this book covers all the features and capabilities of VMware vSphere. You'll learn how to install, configure, operate, manage, and secure the latest release.Covers all the new features and capabilities of the much-anticipated new release of VMware vSphereDiscusses the planning, installation, operation, and management for the latest releaseReviews migration to the latest vSphere softwareOffers hands-on instruction and clear explanations with real-world examples Mastering VMware vSphere is the

  12. Sphere-shaped nano-hydroxyapatite/chitosan/gelatin 3D porous scaffolds increase proliferation and osteogenic differentiation of human induced pluripotent stem cells from gingival fibroblasts

    International Nuclear Information System (INIS)

    Ji, Jun; Tong, Xin; Huang, Xiaofeng; Wang, Tiancong; Lin, Zitong; Cao, Yazhou; Qin, Haiyan; Hu, Qingang; Zhang, Junfeng; Dong, Lei

    2015-01-01

    Hydroxyapatite (HA) is an important component of human bone and bone tissue engineering scaffolds. A plethora of bone tissue engineering scaffolds have been synthesized so far, including nano-HA/chitosan/gelatin (nHA/CG) scaffolds; and for seeding cells, stem cells, especially induced pluripotent stem cells (iPSCs), have been a promising cell source for bone tissue engineering recently. However, the influence of different HA nano-particle morphologies on the osteogenic differentiation of human iPSCs (hiPSCs) from human gingival fibroblasts (hGFs) is unknown. The purpose of this study was to investigate the osteogenic differentiation of hiPSCs from hGFs seeded on nHA/CG scaffolds with 2 shapes (rod and sphere) of nHA particles. Firstly, hGFs isolated from discarded normal gingival tissues were reprogrammed into hiPSCs. Secondly, hiPSCs were seeded on rod-like nHA/CG (rod-nHA/CG) and sphere-shaped nHA/CG (sphere-nHA/CG) scaffolds respectively and then cell/scaffold complexes were cultured in vitro. Scanning electron microscope, hematoxyline and eosin (HE) staining, Masson’s staining, and quantitative real-time polymerase chain reaction techniques were used to examine hiPSC morphology, proliferation, and differentiation on rod-nHA/CG and sphere-nHA/CG scaffolds. Finally, hiPSCs composited with 2 kinds of nHA/CG were transplanted in vivo in a subcutaneous implantation model for 12 weeks; pure scaffolds were also transplanted as a blank control. HE, Masson’s, and immunohistochemistry staining were applied to detect new bone regeneration ability. The results showed that sphere-nHA/CG significantly increased hiPSCs from hGF proliferation and osteogenic differentiation in vitro. hiPSCs and sphere-nHA/CG composities generated large bone, whereas hiPSCs and rod-nHA/CG composities produced tiny bone in vivo. Moreover, pure scaffolds without cells almost produced no bone. In conclusion, our work provided a potential innovative bone tissue engineering approach using

  13. Sphere-shaped nano-hydroxyapatite/chitosan/gelatin 3D porous scaffolds increase proliferation and osteogenic differentiation of human induced pluripotent stem cells from gingival fibroblasts.

    Science.gov (United States)

    Ji, Jun; Tong, Xin; Huang, Xiaofeng; Wang, Tiancong; Lin, Zitong; Cao, Yazhou; Zhang, Junfeng; Dong, Lei; Qin, Haiyan; Hu, Qingang

    2015-07-08

    Hydroxyapatite (HA) is an important component of human bone and bone tissue engineering scaffolds. A plethora of bone tissue engineering scaffolds have been synthesized so far, including nano-HA/chitosan/gelatin (nHA/CG) scaffolds; and for seeding cells, stem cells, especially induced pluripotent stem cells (iPSCs), have been a promising cell source for bone tissue engineering recently. However, the influence of different HA nano-particle morphologies on the osteogenic differentiation of human iPSCs (hiPSCs) from human gingival fibroblasts (hGFs) is unknown. The purpose of this study was to investigate the osteogenic differentiation of hiPSCs from hGFs seeded on nHA/CG scaffolds with 2 shapes (rod and sphere) of nHA particles. Firstly, hGFs isolated from discarded normal gingival tissues were reprogrammed into hiPSCs. Secondly, hiPSCs were seeded on rod-like nHA/CG (rod-nHA/CG) and sphere-shaped nHA/CG (sphere-nHA/CG) scaffolds respectively and then cell/scaffold complexes were cultured in vitro. Scanning electron microscope, hematoxyline and eosin (HE) staining, Masson's staining, and quantitative real-time polymerase chain reaction techniques were used to examine hiPSC morphology, proliferation, and differentiation on rod-nHA/CG and sphere-nHA/CG scaffolds. Finally, hiPSCs composited with 2 kinds of nHA/CG were transplanted in vivo in a subcutaneous implantation model for 12 weeks; pure scaffolds were also transplanted as a blank control. HE, Masson's, and immunohistochemistry staining were applied to detect new bone regeneration ability. The results showed that sphere-nHA/CG significantly increased hiPSCs from hGF proliferation and osteogenic differentiation in vitro. hiPSCs and sphere-nHA/CG composities generated large bone, whereas hiPSCs and rod-nHA/CG composities produced tiny bone in vivo. Moreover, pure scaffolds without cells almost produced no bone. In conclusion, our work provided a potential innovative bone tissue engineering approach using

  14. Dielectric-based subwavelength metallic meanders for wide-angle band absorbers.

    Science.gov (United States)

    Shen, Su; Qiao, Wen; Ye, Yan; Zhou, Yun; Chen, Linsen

    2015-01-26

    We propose nano-meanders that can achieve wide-angle band absorption in visible regime. The nano-meander consists of a subwavelength dielectric grating covered by continuous ultra-thin Aluminum film (less than one tenth of the incident wavelength). The excited photonic resonant modes, such as cavity mode, surface plasmonic mode and Rayleigh-Wood anomaly, are discussed in detail. Nearly total resonant absorption due to funneling mechanism in the air nano-groove is almost invariant with large incident angle in transverse magnetic polarization. From both the structural geometry and the nanofabrication point of view, the light absorber has a very simple geometrical structure and it is easy to be integrated into complex photonic devices. The highly efficient angle-robust light absorber can be potential candidate for a range of passive and active photonic applications, including solar-energy harvesting as well as producing artificial colors on a large scale substrate.

  15. Action of colloidal silica films on different nano-composites

    Directory of Open Access Journals (Sweden)

    S. Abdalla

    Full Text Available Nano-composite films have been the subject of extensive work to develop the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nano-particles size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that form an insulating film between conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of 4 high pure amorphous polymer films: polymethylmethacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher break down performance is a character of polyimide PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer. Keywords: Dielectric break down, Polymers, Nano-composite, Colloidal silica

  16. Topology optimization of nano-photonic systems

    DEFF Research Database (Denmark)

    Elesin, Yuriy; Wang, Fengwen; Andkjær, Jacob Anders

    2012-01-01

    We describe recent developments within nano-photonic systems design based on topology optimization. Applications include linear and non-linear optical waveguides, slow-light waveguides, as well as all-dielectric cloaks that minimize scattering or back-scattering from hard obstacles.......We describe recent developments within nano-photonic systems design based on topology optimization. Applications include linear and non-linear optical waveguides, slow-light waveguides, as well as all-dielectric cloaks that minimize scattering or back-scattering from hard obstacles....

  17. Switching mechanism due to the spontaneous emission cancellation in photonic band gap materials doped with nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, Canada N6A 3K7 (Canada)]. E-mail: msingh@uwo.ca

    2007-03-26

    We have investigated the switching mechanism due to the spontaneous emission cancellation in a photonic band gap (PBG) material doped with an ensemble of four-level nano-particles. The effect of the dipole-dipole interaction has also been studied. The linear susceptibility has been calculated in the mean field theory. Numerical simulations for the imaginary susceptibility are performed for a PBG material which is made from periodic dielectric spheres. It is predicted that the system can be switched between the absorbing state and the non-absorbing state by changing the resonance energy within the energy bands of the photonic band gap material.0.

  18. Study of surface-modified PVP gate dielectric in organic thin film transistors with the nano-particle silver ink source/drain electrode.

    Science.gov (United States)

    Yun, Ho-Jin; Ham, Yong-Hyun; Shin, Hong-Sik; Jeong, Kwang-Seok; Park, Jeong-Gyu; Choi, Deuk-Sung; Lee, Ga-Won

    2011-07-01

    We have fabricated the flexible pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics treated by CF4/O2 plasma on poly[ethersulfones] (PES) substrate. The solution of gate dielectrics is made by adding methylated poly[melamine-co-formaldehyde] (MMF) to PVP. The PVP gate dielectric layer was cross linked at 90 degrees under UV ozone exposure. Source/drain electrodes are formed by micro contact printing (MCP) method using nano particle silver ink for the purposes of low cost and high throughput. The optimized OTFT shows the device performance with field effect mobility of the 0.88 cm2/V s, subthreshold slope of 2.2 V/decade, and on/off current ratios of 1.8 x 10(-6) at -40 V gate bias. We found that hydrophobic PVP gate dielectric surface can influence on the initial film morphologies of pentacene making dense, which is more important for high performance OTFTs than large grain size. Moreover, hydrophobic gate dielelctric surface reduces voids and -OH groups that interrupt the carrier transport in OTFTs.

  19. Evolution of the magnesium incorporated amorphous calcium phosphate to nano-crystallized hydroxyapatite in alkaline solution

    Science.gov (United States)

    Zhang, Xiao-Juan; Lin, Dong-Yang; Yan, Xiao-Hui; Wang, Xiao-Xiang

    2011-12-01

    A homogeneous amorphous calcium phosphate (ACP) coating containing magnesium was achieved on titanium substrates by electrochemical deposition (ECD). Its amorphous structure is confirmed by transmission electron microscope (TEM) together with grazing reflection absorption infrared spectroscopy (IR) spectrometer. In the images of high-resolution transmission electron microscope (HRTEM), the ACP spheres are assembled by nano-particles with the diameter of 5-10 nm. In the alkaline environment, nucleation of hydroxyapatite (HAP) occurs on the surfaces of ACP spheres. By consuming the Ca and PO 4 ions inside the ACP spheres, the HAP nuclei grow outward. Confirmed by TEM, the ACP spheres converse to hollow HAP spheres composed of HAP nano-needles. The coating is finally constructed by the HAP nano-needles, which are themselves aggregated by numerous nano-particles.

  20. Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

    International Nuclear Information System (INIS)

    Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

    2014-01-01

    We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H 2 or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H 2 and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H 2 , an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H 2 and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated

  1. Ultralow-k nanoporous organosilicate dielectric films imprinted with dendritic spheres.

    Science.gov (United States)

    Lee, Byeongdu; Park, Young-Hee; Hwang, Yong-Taek; Oh, Weontae; Yoon, Jinhwan; Ree, Moonhor

    2005-02-01

    Integrated circuits that have improved functionality and speed in a smaller package and that consume less power are desired by the microelectronics industry as well as by end users, to increase device performance and reduce costs. The fabrication of high-performance integrated circuits requires the availability of materials with low or ultralow dielectric constant (low-k: k noise in interconnect conductors, but also minimize power dissipation by reducing the capacitance between the interconnects. Here we describe the preparation of low- and ultralow-k nanoporous organosilicate dielectrics from blends of polymethylsilsesquioxane (PMSSQ) precursor with globular ethyl acrylate-terminated polypropylenimine dendrimers, which act as porogens. These dendrimers are found to mix well with the PMSSQ precursor and after their sacrificial thermal decompositions result in closed, spherical pores of <2.0 nm radius with a very narrow distribution even at high loading. This pore size and distribution are the smallest and the narrowest respectively ever achieved in porous spin-on dielectrics. The method therefore successfully delivers low- and ultralow-k PMSSQ dielectric films that should prove very useful in advanced integrated circuits.

  2. Functionalized Multi walled Carbon Nano tubes-Reinforced Viny lester/Epoxy Blend Based Nano composites: Enhanced Mechanical, Thermal, and Electrical Properties

    International Nuclear Information System (INIS)

    Praharaj, A. P.; Behera, D.; Bastia, T. K.; Rout, A. K.

    2015-01-01

    This paper presents a study on the mechanical, thermal, and electrical characterization of a new class of low cost multiphase nano composites consisting of Vinyl ester resin/epoxy (VER/EP) blend (40:60 w/w) reinforced with amine functionalized multi walled carbon nano tubes (f-MWCNTs). Five different sets of VER/EP nano composites are fabricated with addition of 0, 1, 3, 5, and 7 wt.% of f-MWCNTs. A detailed investigation of mechanical properties like tensile strength, impact strength, Young’s modulus, and hardness, thermal properties like thermogravimetric analysis (TGA) and thermal conductivity, electrical properties like dielectric strength, dielectric constant, and electrical conductivity, and corrosive and swelling properties of the nano composites has been carried out. Here, we report significant improvement in all the above properties of the fabricated nano composites with nano filler (f-MWCNTs) addition compared to the virgin blend (0 wt. nano filler loading). The properties are best observed in case of 5 wt.% nano filler loading with gradual deterioration thereafter which may be due to the nucleating tendency of the nano filler particles. Thus the above nano composites could be a preferable candidate for a wide range of structural, thermal, electrical, and solvent based applications.

  3. Scattering of light from small nematic spheres with radial dielectric anisotropy

    International Nuclear Information System (INIS)

    Karacali, H.; Risser, S.M.; Ferris, K.F.

    1997-01-01

    We have calculated the scattering cross sections of small anisotropic nematic droplets embedded in a polymer matrix as a function of the dielectric constants of the nematic and the polymer. We have derived the general form for the Helmholtz wave equation for a droplet which has spatially varying radial anisotropy, and have explicitly solved this equation for three distinct models of the dielectric anisotropy, including one model where the anisotropy increases linearly with droplet radius. Numerical calculations of the scattering amplitudes for droplets much smaller than the wavelength of the incident radiation show that droplets with continual variation in the dielectric anisotropy have much larger scattering amplitude than droplets with fixed anisotropy. The scattering from droplets with linearly varying anisotropy exhibits a scattering minimum for much smaller polymer dielectric constants than the other models. These results show that the scattering from small anisotropic droplets is sensitive to details of the internal structure and anisotropy of the droplet. copyright 1997 The American Physical Society

  4. Dielectric properties of carbon nanotubes/epoxy composites.

    Science.gov (United States)

    Peng, Jin-Ping; Zhang, Hui; Tang, Long-Cheng; Jia, Yu; Zhang, Zhong

    2013-02-01

    Material with high dielectric properties possesses the effect of energy storage and electric field homogenization, which plays an important role in the electrical and electronics domain, especially in the capacitor, electrical machinery and cable realm. In this paper, epoxy-based nanocomposites with high dielectric constant were fabricated by adding pristine and ozone functionalized multi-wall carbon nanotubes (MWCNTs). In the process-related aspect, the favorable technological parameter was obtained via reasonable arrangement and consideration of the dispersing methods including high-speed stirring and three-roller mill. As a result, a uniform dispersion status of MWCNTs in matrix has been guaranteed, which was observed by scanning and transmission electron microscopy. Meanwhile, the influence of different MWCNTs contents and diverse frequencies on the dielectric properties was compared. It was found that the dielectric constant of nano-composites decreased gradually with the increasing of frequency (10(3)-10(6) Hz). Moreover, as the content of MWCNTs increasing, the dielectric constant reached to a maximum of about 1,328 at 10(3) Hz when the pristine MWCNTs content was 0.5 wt.%. Accordingly, the DC conductivity results could interpret the peak value phenomenon by percolation threshold of MWCNTs. In addition, at the fixed content, the dielectric constant of epoxy-based nano-composites with ozone functionalized MWCNTs was lower than that of pristine ones.

  5. Geometric phase from dielectric matrix

    International Nuclear Information System (INIS)

    Banerjee, D.

    2005-10-01

    The dielectric property of the anisotropic optical medium is found by considering the polarized photon as two component spinor of spherical harmonics. The Geometric Phase of a polarized photon has been evaluated in two ways: the phase two-form of the dielectric matrix through a twist and the Pancharatnam phase (GP) by changing the angular momentum of the incident polarized photon over a closed triangular path on the extended Poincare sphere. The helicity in connection with the spin angular momentum of the chiral photon plays the key role in developing these phase holonomies. (author)

  6. Characterization of maximally random jammed sphere packings. III. Transport and electromagnetic properties via correlation functions

    Science.gov (United States)

    Klatt, Michael A.; Torquato, Salvatore

    2018-01-01

    In the first two papers of this series, we characterized the structure of maximally random jammed (MRJ) sphere packings across length scales by computing a variety of different correlation functions, spectral functions, hole probabilities, and local density fluctuations. From the remarkable structural features of the MRJ packings, especially its disordered hyperuniformity, exceptional physical properties can be expected. Here we employ these structural descriptors to estimate effective transport and electromagnetic properties via rigorous bounds, exact expansions, and accurate analytical approximation formulas. These property formulas include interfacial bounds as well as universal scaling laws for the mean survival time and the fluid permeability. We also estimate the principal relaxation time associated with Brownian motion among perfectly absorbing traps. For the propagation of electromagnetic waves in the long-wavelength limit, we show that a dispersion of dielectric MRJ spheres within a matrix of another dielectric material forms, to a very good approximation, a dissipationless disordered and isotropic two-phase medium for any phase dielectric contrast ratio. We compare the effective properties of the MRJ sphere packings to those of overlapping spheres, equilibrium hard-sphere packings, and lattices of hard spheres. Moreover, we generalize results to micro- and macroscopically anisotropic packings of spheroids with tensorial effective properties. The analytic bounds predict the qualitative trend in the physical properties associated with these structures, which provides guidance to more time-consuming simulations and experiments. They especially provide impetus for experiments to design materials with unique bulk properties resulting from hyperuniformity, including structural-color and color-sensing applications.

  7. High resolution imaging of dielectric surfaces with an evanescent field optical microscope

    NARCIS (Netherlands)

    van Hulst, N.F.; Segerink, Franciscus B.; Bölger, B.

    1992-01-01

    An evanescent field optical microscope (EFOM) is presented which employs frustrated total internal reflection o­n a localized scale by scanning a dielectric tip in close proximity to a sample surface. High resolution images of dielectric gratings and spheres containing both topographic and

  8. One step process of decomposition and polymerization to fabricate SiO_2 hollow spheres/polyimide composite for foldable OLEDs

    International Nuclear Information System (INIS)

    Kim, Min Kyu; Kim, Dong Won; Moon, Soo Hyun; Shin, Dong-Wook; Oh, Tae Sik; Yoo, Ji Beom

    2017-01-01

    Graphical abstract: The SiO_2 hollow spheres and polyimide hybrid synthesized using one step process, simultaneous occurrence of decomposition and polymerization (SODP) is useful with a ultra-low dielectric constant and high thermal stability for flexible OLED. - Highlights: • We fabricated hybrid films of SHS/PI by using a one step process with SODP. • The film has ultralow dielectric constant (50 vol% at k = 1.67). • There is no collapse of SiO_2 hollow spheres in the PI matrix after bending test for 50,000 cycles. - Abstract: The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) requires flexible materials with a low dielectric constant as well as materials with excellent electrical, thermal, and mechanical properties for optimal device performance. Hybrid films of SiO_2 hollow spheres (SHS)/polyimide (PI) were prepared using a one-step process, with simultaneous occurrence of decomposition (polystyrene, PS) and polymerization (PI) (SODP). No collapse of SiO_2 hollow spheres in PI was observed from 10 vol% to 60 vol% SHS in hybrid films. The dielectric constant of hybrid films was reduced from 3.45 to 1.67 and was saturated at above 50 vol% of SHS due to the maximum fill factor of SHS in the PI matrix. The thermal stability was excellent up to 500 °C due to the inherent thermal property of PI. After a bending test for 50,000 cycles at a bending radius of 1 mm, the SHS/PI hybrid films retained their dielectric constant and current density. These results indicate the hybrid film to be the most promising candidate for flexible ILDs with a low dielectric constant and high thermal stability for foldable OLEDs.

  9. Dielectric Properties of Polyether Sulfone/Bismaleimide Resin Composite Based on Nanolumina Modified by Super-Critical Ethanol

    Science.gov (United States)

    Chen, Yufei; Li, Zhichao; Teng, Chengjun; Li, Fangliang; Han, Yang

    2016-11-01

    Nano-alumina was chemically modified with super-critical ethanol enabling a surface active coating. Modified nano-alumina was incorporated in polymer blends based on thermoplastic polyether sulfone and thermosetting bismaleimide resin to produce novel nanocomposites designated as SCE-Al2O3/PES-MBAE. In the SCE-Al2O3/PES-MBAE nano-composites, the matrix was originally formed from 4,4'-diamino diphenyl methane bismaleimide (MBMI) using the diluents of 3,3'-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE), while polyether sulfone (PES) was used as toughening agent along with super-critically modified nano-alumina (SCE-Al2O3) as filler material. The content of SCE-Al2O3 was varied from 0 wt.% to 6 wt.%. The nano-composites were characterized for their morphological, spectroscopic and dielectric properties. Fourier transform infrared spectroscopy (FT-IR) indicated that ethanol molecules had adhered to the surface of the nano-Al2O3 in super-critical state. A reaction between MBMI and allyl compound occurred and SCE-Al2O3 was doped into the polymer matrix. Volume resistivity of the composite initially increased and then decreased. The modification due to SCE-Al2O3 could overcome the undesirable impact of PES by using a bare minimum level of SCE-Al2O3. The dielectric constant ( ɛ) and dielectric loss (tan δ) as in the case of volume resistivity were initially increased and then decreased with the content of SCE-Al2O3 in the composite. The dielectric constant, dielectric loss and dielectric strength of SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE nano-composite were 3.53 (100 Hz), 1.52 × 10-3 (100 Hz) and 15.66 kV/mm, respectively, which indicated that the dielectric properties of the composite fulfilled the basic requirements of electrical and insulating material. It was evident from the morphological analysis that the SCE-Al2O3 was evenly dispersed at the nanoscale; for example, the size of SCE-Al2O3 in SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE measured less than 50 nm.

  10. Infrared and THz spectroscopy of nanostructured dielectrics

    Directory of Open Access Journals (Sweden)

    Jan Petzelt

    2009-09-01

    Full Text Available Results achieved using the infrared/THz spectroscopy of various inhomogeneous dielectrics in the Department of Dielectrics, Institute of Physics, Prague, during the last decade are briefly reviewed. The discussion concerns high-permittivity ceramics with inevitable low-permittivity dead layers along the grain boundaries, relaxor ferroelectrics with highly anisotropic polar nano-regions, classical matrix-type composites, core-shell composites, filled nanoporous glasses, polycrystalline and epitaxial thin films, heterostructures and superlattices on dielectric substrates. The analysis using models based on the effective medium approach is discussed. The importance of depolarizing field and of the percolation of components on the effective ac dielectric response and the excitations contributing to it are emphasized.

  11. Classical molecular dynamics and quantum abs-initio studies on lithium-intercalation in interconnected hollow spherical nano-spheres of amorphous Silicon

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Malik, R.; Prakash, S.

    2016-01-01

    A high concentration of lithium, corresponding to charge capacity of ~4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnec......A high concentration of lithium, corresponding to charge capacity of ~4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently...... interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues...... that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale....

  12. Synthesis and characterization of nano hydroxyapatite using reverse micro emulsions as nano reactors

    International Nuclear Information System (INIS)

    Amin, S.; Siddique, T.

    2015-01-01

    In the present work reverse micro emulsion has been employed as nano reactors to synthesize nano crystalline Hydroxyapatite (HA). Two precursors; calcium and phosphate with different counter ions of each were used for the synthesis of HA at two different temperatures. To maintain the emulsified nano reactor, cyclohexane, TX-100 and 1-butanol including phosphate precursor was the continuous phase while aqueous Ca precursor solution was taken as the dispersed phase. Nano crystalline particles thus produced were evaluated on the basis of synthesis route, counter ions and temperature. It has been shown that emulsified nano reactors control the morphology, particle size and minimize phase transformation of HA. Characterizations of nano powder of HA are carried out using x-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), and scanning electron microscopy (SEM). HA crystallite size was found to be in the range of 20-25 nm whereas the morphology of nano particles changed from spheres to rods. (author)

  13. One step process of decomposition and polymerization to fabricate SiO{sub 2} hollow spheres/polyimide composite for foldable OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Kyu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Dong Won; Moon, Soo Hyun [School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Shin, Dong-Wook [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Oh, Tae Sik [School of Mechanical and ICT Convergence Engineering, Sunmoon University, Asan 336-708 (Korea, Republic of); Yoo, Ji Beom, E-mail: jbyoo@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-03-15

    Graphical abstract: The SiO{sub 2} hollow spheres and polyimide hybrid synthesized using one step process, simultaneous occurrence of decomposition and polymerization (SODP) is useful with a ultra-low dielectric constant and high thermal stability for flexible OLED. - Highlights: • We fabricated hybrid films of SHS/PI by using a one step process with SODP. • The film has ultralow dielectric constant (50 vol% at k = 1.67). • There is no collapse of SiO{sub 2} hollow spheres in the PI matrix after bending test for 50,000 cycles. - Abstract: The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) requires flexible materials with a low dielectric constant as well as materials with excellent electrical, thermal, and mechanical properties for optimal device performance. Hybrid films of SiO{sub 2} hollow spheres (SHS)/polyimide (PI) were prepared using a one-step process, with simultaneous occurrence of decomposition (polystyrene, PS) and polymerization (PI) (SODP). No collapse of SiO{sub 2} hollow spheres in PI was observed from 10 vol% to 60 vol% SHS in hybrid films. The dielectric constant of hybrid films was reduced from 3.45 to 1.67 and was saturated at above 50 vol% of SHS due to the maximum fill factor of SHS in the PI matrix. The thermal stability was excellent up to 500 °C due to the inherent thermal property of PI. After a bending test for 50,000 cycles at a bending radius of 1 mm, the SHS/PI hybrid films retained their dielectric constant and current density. These results indicate the hybrid film to be the most promising candidate for flexible ILDs with a low dielectric constant and high thermal stability for foldable OLEDs.

  14. Fabrication of Nonvolatile Memory Effects in High-k Dielectric Thin Films Using Electron Irradiation

    International Nuclear Information System (INIS)

    Park, Chanrock; Cho, Daehee; Kim, Jeongeun; Hwang, Jinha

    2010-01-01

    Electron Irradiation can be applied towards nano-floating gate memories which are recognized as one of the next-generation nonvolatile memory semiconductors. NFGMs can overcome the preexisting limitations encountered in Dynamic Random Access Memories and Flash memories with the excellent advantages, i. e. high-density information storage, high response speed, high compactness, etc. The traditional nano-floating gate memories are fabricated through multi-layered nano structures of the dissimilar materials where the charge-trapping portions are sandwiched into the high-k dielectrics. However, this work reports the unique nonvolatile responses in single-layered high-k dielectric thin films if irradiated with highly accelerated electron beams. The implications of the electron irradiation will be discussed towards high-performance nano-floating gate memories

  15. Nanostructure multilayer dielectric materials for capacitors and insulators

    Science.gov (United States)

    Barbee, Jr., Troy W.; Johnson, Gary W.

    1998-04-21

    A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3) in alternating layers to form a nano-laminate.

  16. Nano-honeycomb structured transparent electrode for enhanced light extraction from organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xiao-Bo; Qian, Min; Wang, Zhao-Kui, E-mail: zkwang@suda.edu.cn, E-mail: lsliao@suda.edu.cn; Liao, Liang-Sheng, E-mail: zkwang@suda.edu.cn, E-mail: lsliao@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, Jiangsu 215123 (China)

    2015-06-01

    A universal nano-sphere lithography method has been developed to fabricate nano-structured transparent electrode, such as indium tin oxide (ITO), for light extraction from organic light-emitting diodes (OLEDs). Perforated SiO{sub 2} film made from a monolayer colloidal crystal of polystyrene spheres and tetraethyl orthosilicate sol-gel is used as a template. Ordered nano-honeycomb pits on the ITO electrode surface are obtained by chemical etching. The proposed method can be utilized to form large-area nano-structured ITO electrode. More than two folds' enhancement in both current efficiency and power efficiency has been achieved in a red phosphorescent OLED which was fabricated on the nano-structured ITO substrate.

  17. UV response on dielectric properties of nano nematic liquid crystal

    Directory of Open Access Journals (Sweden)

    Kamal Kumar Pandey

    2018-03-01

    Full Text Available In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range. Keywords: Dielectric permittivity, Relaxation frequency, Nematic liquid crystal, UV light irradiation

  18. Enhanced optical-to-THz conversion efficiency of photoconductive antenna using dielectric nano-layer encapsulation

    Science.gov (United States)

    Gupta, Abhishek; Rana, Goutam; Bhattacharya, Arkabrata; Singh, Abhishek; Jain, Ravikumar; Bapat, Rudheer D.; Duttagupta, S. P.; Prabhu, S. S.

    2018-05-01

    Photoconductive antennas (PCAs) are among the most conventional devices used for emission as well as detection of terahertz (THz) radiation. However, due to their low optical-to-THz conversion efficiencies, applications of these devices in out-of-laboratory conditions are limited. In this paper, we report several factors of enhancement in THz emission efficiency from conventional PCAs by coating a nano-layer of dielectric (TiO2) on the active area between the electrodes of a semi-insulating GaAs-based device. Extensive experiments were done to show the effect of thicknesses of the TiO2 layer on the THz power enhancement with different applied optical power and bias voltages. Multiphysics simulations were performed to elucidate the underlying physics behind the enhancement of efficiency of the PCA. Additionally, this layer increases the robustness of the electrode gaps of the PCAs with high electrical insulation as well as protect it from external dust particles.

  19. Experiment SPHERE status 2008

    International Nuclear Information System (INIS)

    Shaulov, S.B.; Besshapov, S.P.; Kabanova, N.V.; Sysoeva, T.I.; Antonov, R.A.; Anyuhina, A.M.; Bronvech, E.A.; Chernov, D.V.; Galkin, V.I.; Tkaczyk, W.; Finger, M.; Sonsky, M.

    2009-01-01

    The expedition carried out in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 m over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 10 16 -10 18 eV.

  20. Experiment SPHERE status 2008

    Energy Technology Data Exchange (ETDEWEB)

    Shaulov, S.B., E-mail: shaul@sci.lebedev.r [P.N.Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospect 53, Moscow 119991 (Russian Federation); Besshapov, S.P.; Kabanova, N.V.; Sysoeva, T.I. [P.N.Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospect 53, Moscow 119991 (Russian Federation); Antonov, R.A.; Anyuhina, A.M.; Bronvech, E.A.; Chernov, D.V.; Galkin, V.I. [Skobeltsyn Institute of Nuclear Physics, Lomonosov State University, Moscow 119992 (Russian Federation); Tkaczyk, W. [Department of Experimental Physics of University of Lodz (Poland); Finger, M. [Karlov University, Prague (Czech Republic); Sonsky, M. [COMPAS Consortium, Turnov (Czech Republic)

    2009-12-15

    The expedition carried out in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 m over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 10{sup 16}-10{sup 18} eV.

  1. Theory of the dielectric wakefield accelerator

    International Nuclear Information System (INIS)

    Mtingwa, S.K.

    1990-10-01

    The general theory for all angular modes m of the dielectric wakefield accelerator is reformulated. The expressions for the accelerating electric fields and transverse wake forces are written in terms of matrices, the zeros of one of which determine the excitation frequencies of the dielectric structure. In this scheme it is possible to obtain a maximum accelerating gradient of 2.0 megavolts per meter per nanoCoulomb of driver beam charge, for a driver beam of 0.7 millimeters rms bunch length. 29 refs., 5 figs

  2. NiCo2O4 surface coating Li[Ni0.03Mn1.97]O4 micro-/nano- spheres as cathode material for high-performance lithium ion battery

    Science.gov (United States)

    Ye, Pan; Dong, Hui; Xu, Yunlong; Zhao, Chongjun; Liu, Dong

    2018-01-01

    Here we report a novel transitional metal oxide (NiCo2O4) coated Li[Ni0.03Mn1.97]O4 micro-/nano- spheres as high-performance Li-ion battery cathode material. A thin layer of ∼10 nm NiCo2O4 was formed by simple wet-chemistry approach adjacent to the surface of Li[Ni0.03Mn1.97]O4 micro-/nano- spheres, leading to significantly enhanced battery electrochemical performance. The optimized sample(1 wt%) not only delivers excellent discharge capacity and cycling stability improvement at both room temperature and elevated temperatures, but also effectively prevents Mn dissolution while retaining its coating structure intact according to XRF and TEM results. The CV and EIS break-down analysis indicated a much faster electrochemical reaction kinetics, more reversible electrode process and greatly reduced charge transfer and Warburg resistance, clearly illustrating the dual role of NiCo2O4 coating to boost electron transport and Li+ diffusion, and alleviation of manganese dissolving. This approach may render as an efficient technique to realize high-performance lithium ion battery cathode material.

  3. Mass production of polymer nano-wires filled with metal nano-particles.

    Science.gov (United States)

    Lomadze, Nino; Kopyshev, Alexey; Bargheer, Matias; Wollgarten, Markus; Santer, Svetlana

    2017-08-17

    Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.

  4. Smith-Purcell radiation from a chain of spheres

    International Nuclear Information System (INIS)

    Lekomtsev, K V; Strikhanov, M N; Tishchenko, A A

    2010-01-01

    Smith-Purcell and diffraction radiation were investigated. These types of radiation appear when a charged particle moves close to a conducting target. Spectral and angular distribution of diffraction radiation from the non-periodic chain of spheres is obtained analytically; local field effects are discussed. Analytical expression for the distribution of Smith-Purcell radiation from the periodic chain of spheres is obtained as well. For the first time it has been shown, that Smith-Purcell radiation for such a system is distributed over the cone. The results are investigated for the particles of different sizes, dielectric and metal, and for both ultrarelativistic and nonrelativistic cases.

  5. Phase-controlled preparation of TiO{sub 2} films and micro(nano)spheres by low-temperature chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingsong, E-mail: wangms@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Qihui; Yu, Haiyan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Hur, Seung Hyun [Department of Chemical Engineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Kim, Eui Jung, E-mail: ejkim@ulsan.ac.kr [Department of Chemical Engineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

    2013-11-25

    Highlights: •Simultaneously preparation of TiO{sub 2} films and sphere-like precipitates by low-temperature chemical bath deposition. •The same building blocks observed in the films and precipitates. •Cluster-by-cluster attachment is succeeded by the ion-by-ion growth. •Phase-controlled growth of TiO{sub 2} by the effects of solvent or fluorine ion. -- Abstract: TiO{sub 2} films and micro(nano)spheres have been simultaneously prepared by means of low-temperature chemical bath deposition (CBD). The films and precipitates are found to be constructed of the same building blocks regardless of the bath conditions. Thin nanosheets of ca. 20 nm in thickness serve as the building blocks of rutile TiO{sub 2} grown in an acidic bath. They aggregate to form spheres to reduce the surface energy of the precipitates, while in the films they grow into discrete crystallites on the seeded substrate. Fine control over the crystalline phase of TiO{sub 2} is achieved by replacing some water with ethanol or the addition of NH{sub 4}F. A gradual transition from rutile to anatase is observed as the ethanol and NH{sub 4}F contents are increased. Moreover, the crystallite size of TiO{sub 2} is significantly reduced and there exists monodisperse nanoparticles and aggregate microspheres in the products modified with ethanol and NH{sub 4}F, respectively. This size-dependent phase transition is consistent with previous theoretical and thermodynamic studies. The facile tune of the TiO{sub 2} phase by low-temperature CBD method may be useful to improve the performance of TiO{sub 2} for its various applications.

  6. Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nano tubes and Their Applications

    International Nuclear Information System (INIS)

    Motshekga, S.C.; Pillai, S.K.; Ray, S.S.; Motshekga, S.C.; Ray, S.S.; Jalama, K.; Krause, Rui.W.M.

    2012-01-01

    The study of coating carbon nano tubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nano tubes in various applications, it is necessary to attach functional groups or other nano structures to their surface. The combination of the distinctive properties of carbon nano tubes and metal/oxides is expected to be applied in field emission displays, nano electronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nano tube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

  7. The Terahertz Scattering Analysis of Rough Metallic and Dielectric Targets

    Directory of Open Access Journals (Sweden)

    Mou Yuan

    2018-02-01

    Full Text Available The terahertz scattering characteristics of metallic and dielectric rough targets is important for the investigation of the terahertz radar targets properties. According to the stationary phase theory and scalar approximation, if the radius of curvature at any point of the surface is much larger than the incident wavelength, and the wavelength is also much longer than the surface height function and Root-Mean-Square (RMS surface slope, the coherent and incoherent scattering Radar Cross Section (RCS of rough metallic and dielectric targets can be obtained. Based on the stationary phase approximation, the coherent RCS of rough conductors, smooth dielectric targets and rough dielectric targets can be easily deputed. The scattering characteristics of electrically large smooth Al and painted spheres are investigated in this paper, and the calculated RCS are verified by Mie scattering theory, the error is less than 0.1 dBm2. Based on lambert theory, it is demonstrated that the incoherent RCS is analyzed with better precision if the rough surfaces are divided into much more facets. In this paper, the coherent and incoherent scattering of rough Al and painted spheres are numerically observed, and the effects of surface roughness and materials are analyzed. The conclusions provide theoretical foundation for the terahertz scattering characteristics of electrically large rough targets.

  8. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Directory of Open Access Journals (Sweden)

    Zhong Kuo

    2018-03-01

    Full Text Available In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  9. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Science.gov (United States)

    Zhong, Kuo; Song, Kai; Clays, Koen

    2018-03-01

    In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal) lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs) of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM) inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  10. Impedance and modulus spectroscopic study of nano hydroxyapatite

    Science.gov (United States)

    Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.

    2016-05-01

    Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.

  11. Nano-JASMINE Data Analysis and Publication

    Science.gov (United States)

    Yamada, Y.; Hara, T.; Yoshioka, S.; Kobayashi, Y.; Gouda, N.; Miyashita, H.; Hatsutori, Y.; Lammers, U.; Michalik, D.

    2012-09-01

    The core data reduction for the Nano-JASMINE mission is planned to be done with Gaia's Astrometric Global Iterative Solution (AGIS). A collaboration between the Gaia AGIS and Nano-JASMINE teams on the Nano-JASMINE data reduction started in 2007. The Nano-JASMINE team writes codes to generate AGIS input, and this is called Initial Data Treament (IDT). Identification of observed stars and their observed field of view, getting color index, are different from those of Gaia because Nano-JASMINE is ultra small satellite. For converting centroiding results on detector to the celestial sphere, orbit and attitude data of the satellite are used. In Nano-JASMINE, orbit information is derived from on board GPS data and attitude is processed from on-board star sensor data and on-ground Kalman filtering. We also show the Nano-JASMINE goals, status of the data publications and utilizations, and introduce the next Japanese space astrometric mission.

  12. Structural, dielectric and ferroelectric studies of (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} magnetoelectric nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Khader, S. Abdul, E-mail: khadersku@gmail.com; Sankarappa, T., E-mail: sankarappa@rediffmail.com [Department of Physics, Gulbarga University, Gulbarga-585106, Karnataka (India); Muneeswaran, M.; Giridharan, N. V. [Department of Physics, National Institute of Technology, Tiruchirapalli-620015 (India)

    2016-05-06

    The Particulate nano-composites of ferrite and ferroelectric phases having the general formula (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} (x=15%, 30% and 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO{sub 3} (BT) and highly magneto-strictive magnetic component Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4}(MCZF). The presence of constituent phases of ferrite, ferroelectric and their composites were probed and confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). The variation of dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz at room temperature were carried out using a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric data has been thoroughly analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model. The ferroelectric properties of synthesized magneto-electric nano-composites were measured using P-E loop tracer.

  13. Plasmon enhanced near-field radiative heat transfer for graphene covered dielectrics

    NARCIS (Netherlands)

    Svetovoy, Vitaly; van Zwol, P.J.; Chevrier, J.

    2012-01-01

    It is shown that a graphene layer on top of a dielectric slab can dramatically influence the ability of this dielectric for radiative heat exchange turning a poor heat emitter/absorber into a good one and vice versa. The effect of graphene is related to thermally excited plasmons. The frequency of

  14. The mechanical properties modeling of nano-scale materials by molecular dynamics

    NARCIS (Netherlands)

    Yuan, C.; Driel, W.D. van; Poelma, R.; Zhang, G.Q.

    2012-01-01

    We propose a molecular modeling strategy which is capable of mod-eling the mechanical properties on nano-scale low-dielectric (low-k) materials. Such modeling strategy has been also validated by the bulking force of carbon nano tube (CNT). This modeling framework consists of model generation method,

  15. Classical molecular dynamics and quantum ab-initio studies on lithium-intercalation in interconnected hollow spherical nano-spheres of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, A. [Atomic Scale Modelling and Materials, Department of Energy Conversion and Storage, Technical University of Denmark, Rios Campus, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Malik, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India); Prakash, S. [Defense Metallurgical Research Laboratory, Hyderabad (India); Sarkar, T.; Bharadwaj, M.D. [Center for Study of Science Technology and Policy, Bangalore 560094 (India); Aich, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India); Ghosh, S., E-mail: sudipto@metal.iitkgp.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India)

    2016-04-25

    A high concentration of lithium, corresponding to charge capacity of ∼4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale. - Highlights: • Interconnected nanoshells of amorphous Si: best available lithium ion cell anode. • High cycle life not understood in the light of poor K{sub IC} of amorphous Si. • MD reveals: atomic density of interconnected structure is ∼16% less than bulk Si. • Leads to drastic reduction (DFT) in lithiation σ & metal like e{sup −} structure (high K{sub IC}). • Lowering of lithiation σ and increase in K{sub IC} result in high cycle life.

  16. Mastering VMware vSphere 5.5

    CERN Document Server

    Lowe, Scott; Guthrie, Forbes; Liebowitz, Matt; Atwell, Josh

    2013-01-01

    The 2013 edition of the bestselling vSphere book on the market Virtualization remains the hottest trend in the IT world, and VMware vSphere is the industry's most widely deployed virtualization solution. The demand for IT professionals skilled in virtualization and cloud-related technologies is great and expected to keep growing. This comprehensive Sybex guide covers all the features and capabilities of VMware vSphere, showing administrators step by step how to install, configure, operate, manage, and secure it. This perfect blend of hands-on instruction, conceptual explanation, and practic

  17. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2016-01-01

    One prominent method of modifying the properties of dielectric elastomers (DEs) is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting...... and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2) particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0...

  18. vSphere virtual machine management

    CERN Document Server

    Fitzhugh, Rebecca

    2014-01-01

    This book follows a step-by-step tutorial approach with some real-world scenarios that vSphere businesses will be required to overcome every day. This book also discusses creating and configuring virtual machines and also covers monitoring virtual machine performance and resource allocation options. This book is for VMware administrators who want to build their knowledge of virtual machine administration and configuration. It's assumed that you have some experience with virtualization administration and vSphere.

  19. Research Update: Facile synthesis of CoFe2O4 nano-hollow spheres for efficient bilirubin adsorption

    Science.gov (United States)

    Rakshit, Rupali; Pal, Monalisa; Chaudhuri, Arka; Mandal, Madhuri; Mandal, Kalyan

    2015-11-01

    Herein, we report an unprecedented bilirubin (BR) adsorption efficiency of CoFe2O4 (CFO) nanostructures in contrast to the commercially available activated carbon and resin which are generally used for haemoperfusion and haemodialysis. We have synthesized CFO nanoparticles of diameter 100 nm and a series of nano-hollow spheres of diameter 100, 160, 250, and 350 nm using a simple template free solvothermal technique through proper variation of reaction time and capping agent, oleylamine (OLA), respectively, and carried out SiO2 coating by employing Stöber method. The comparative BR adsorption study of CFO and SiO2 coated CFO nanostructures indicates that apart from porosity and hollow configuration of nanostructures, the electrostatic affinity between anionic carboxyl group of BR and cationic amine group of OLA plays a significant role in adsorbing BR. Finally, we demonstrate that the BR adsorption capacity of the nanostructures can be tailored by varying the morphology as well as size of the nanostructures. We believe that our developed magnetic nanostructures could be considered as a potential material towards therapeutic applications against hyperbilirubinemia.

  20. Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Saoud, Khaled [Virginia Commonwealth University-Qatar, Doha (Qatar); Alsoubaihi, Rola [Virginia Commonwealth University, Richmond, VA (United States); Bensalah, Nasr [Qatar University, Doha (Qatar); Bora, Tanujjal [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman); Bertino, Massimo [Virginia Commonwealth University, Richmond, VA (United States); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman)

    2015-03-15

    Highlights: • Synthesis of supported Ag NPs on ZnO nanorods using open vessel microwave reactor. • Use of the Ag/ZnO NPs as an efficient visible light photocatalyst. • Complete degradation of methylene blue in 1 h with 0.5 g/L Ag/ZnO NPs. - Abstract: We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescence and UV–vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.

  1. Investigations on the structural and optical properties of sphere-shaped indium nitride (InN)

    Energy Technology Data Exchange (ETDEWEB)

    Bagavath, C.; Kumar, J. [Anna University, Crystal Growth Centre, Chennai, Tamil Nadu (India); Nasi, L. [IMEM-CNR, Parma (Italy)

    2017-04-15

    Indium nitride (InN) sphere-shaped micro crystals and nano crystals were made using sol-gel method. The crystalline size of the samples were calculated using X-ray diffraction, which were found to increase with the increase of nitridation temperature and time. High resolution-transmission electron microscopy images exhibited the distinct sphere shape of InN with different size of micro and nanometers. The calculated band gap of InN spheres using photo luminescence and UV-visible absorption spectra, was found to be 1.2 eV. Optical phonon modes of InN were determined from micro-Raman studies. (orig.)

  2. Editorial Emerging Multifunctional Nano structures

    International Nuclear Information System (INIS)

    Fan, H.; Lu, Y.; Ramanath, G.; Pomposo, J.A.

    2009-01-01

    The interest in emerging nano structures is growing exponentially since they are promising building blocks for advanced multifunctional nano composites. In recent years, an evolution from the controlled synthesis of individual monodisperse nanoparticles to the tailored preparation of hybrid spherical and also unsymmetrical multiparticle nano structures is clearly observed. As a matter of fact, the field of nano structures built around a nano species such as inside, outside, and next to a nanoparticle is becoming a new evolving area of research and development with potential applications in improved drug delivery systems, innovative magnetic devices, biosensors, and highly efficient catalysts, among several others Emerging nano structures with improved magnetic, conducting and smart characteristics are currently based on the design, synthesis, characterization and modeling of multifunctional nano object-based materials. In fact, core-shell nanoparticles and other related complex nano architectures covering a broad spectrum of materials (from metal and metal oxide to fused carbon, synthetic polymer, and bio polymer structures) to nano structure morphologies (spherical, cylindrical, star-like, etc.) are becoming the main building blocks for next generation of drug delivery systems, advanced sensors and biosensors, or improved nano composites. The five papers presented in this special issue examine the preparation and characterization of emerging multifunctional materials, covering from hybrid asymmetric structures to engineering nano composites.

  3. Internal homogenization: effective permittivity of a coated sphere.

    Science.gov (United States)

    Chettiar, Uday K; Engheta, Nader

    2012-10-08

    The concept of internal homogenization is introduced as a complementary approach to the conventional homogenization schemes, which could be termed as external homogenization. The theory for the internal homogenization of the permittivity of subwavelength coated spheres is presented. The effective permittivity derived from the internal homogenization of coreshells is discussed for plasmonic and dielectric constituent materials. The effective model provided by the homogenization is a useful design tool in constructing coated particles with desired resonant properties.

  4. Cell characteristics of FePt nano-dot memories with a high-k Al2O3 blocking oxide

    International Nuclear Information System (INIS)

    Lee, Gae Hun; Lee, Jung Min; Yang, Hyung Jun; Song, Yun Heub; Bea, Ji Cheol; Tanaka, Testsu

    2012-01-01

    The cell characteristics of an alloy FePt nano-dot (ND) charge trapping memory with a high-k dielectric as a blocking oxide was investigated. Adoption of a high-k Al 2 O 3 material as a blocking oxide for the metal nano-dot memory provided a superior scaling of the operation voltage compared to silicon oxide under a similar gate leakage level. For the 40-nm-thick high-k (Al 2 O 3 ) blocking oxide, we confirmed an operation voltage reduction of ∼7 V under the same memory window on for silicon dioxide. Also, this device showed a large memory window of 7.8 V and a low leakage current under 10 -10 A in an area of Φ 0.25 mm. From these results, the use of a dielectric (Al 2 O 3 ) as a blocking oxide for a metal nano-dot device is essential, and a metal nano-dot memory with a high-k dielectric will be one of the candidates for a high-density non-volatile memory device.

  5. Statistical Modelling of the Soil Dielectric Constant

    Science.gov (United States)

    Usowicz, Boguslaw; Marczewski, Wojciech; Bogdan Usowicz, Jerzy; Lipiec, Jerzy

    2010-05-01

    The dielectric constant of soil is the physical property being very sensitive on water content. It funds several electrical measurement techniques for determining the water content by means of direct (TDR, FDR, and others related to effects of electrical conductance and/or capacitance) and indirect RS (Remote Sensing) methods. The work is devoted to a particular statistical manner of modelling the dielectric constant as the property accounting a wide range of specific soil composition, porosity, and mass density, within the unsaturated water content. Usually, similar models are determined for few particular soil types, and changing the soil type one needs switching the model on another type or to adjust it by parametrization of soil compounds. Therefore, it is difficult comparing and referring results between models. The presented model was developed for a generic representation of soil being a hypothetical mixture of spheres, each representing a soil fraction, in its proper phase state. The model generates a serial-parallel mesh of conductive and capacitive paths, which is analysed for a total conductive or capacitive property. The model was firstly developed to determine the thermal conductivity property, and now it is extended on the dielectric constant by analysing the capacitive mesh. The analysis is provided by statistical means obeying physical laws related to the serial-parallel branching of the representative electrical mesh. Physical relevance of the analysis is established electrically, but the definition of the electrical mesh is controlled statistically by parametrization of compound fractions, by determining the number of representative spheres per unitary volume per fraction, and by determining the number of fractions. That way the model is capable covering properties of nearly all possible soil types, all phase states within recognition of the Lorenz and Knudsen conditions. In effect the model allows on generating a hypothetical representative of

  6. Effect of porosity on dielectric properties and microstructure of porous PZT ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, B. Praveen [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India); Kumar, H.H. [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India); Kharat, D.K. [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India)]. E-mail: dkkharat@rediffmail.com

    2006-02-25

    Porous piezoelectric materials are of great interest because of their high hydrostatic figure of merit and low sound velocity, which results in to low acoustic impedance and efficient coupling with medium. Porous lead zirconate titanate (PZT) ceramics with varying porosity was developed using polymethyl methacrylate by burnable plastic spheres (BURPS) process. The porous PZT ceramics were characterized for dielectric constant ({epsilon}), dielectric loss factor (tan {delta}), hydrostatic charge (d {sub h}) and voltage (g {sub h}) coefficients and microstructure. The effect of the porous microstructure on the dielectric constant and loss factor at frequencies of 10-10{sup 5} Hz are discussed in this paper.

  7. Porous Si spheres encapsulated in carbon shells with enhanced anodic performance in lithium-ion batteries

    International Nuclear Information System (INIS)

    Wang, Hui; Wu, Ping; Shi, Huimin; Lou, Feijian; Tang, Yawen; Zhou, Tongge; Zhou, Yiming; Lu, Tianhong

    2014-01-01

    Highlights: • In situ magnesiothermic reduction route for the formation of porous Si@C spheres. • Unique microstructural characteristics of both porous sphere and carbon matrix. • Enhanced anodic performance in term of cycling stability for lithium-ion batteries. - Abstract: A novel type of porous Si–C micro/nano-hybrids, i.e., porous Si spheres encapsulated in carbon shells (porous Si@C spheres), has been constructed through the pyrolysis of polyvinylidene fluoride (PVDF) and subsequent magnesiothermic reduction methodology by using SiO 2 spheres as precursors. The as-synthesized porous Si@C spheres have been applied as anode materials for lithium-ion batteries (LIBs), and exhibit enhanced anodic performance in term of cycling stability compared with bare Si spheres. For example, the porous Si@C spheres are able to exhibit a high reversible capacity of 900.0 mA h g −1 after 20 cycles at a current density of 0.05 C (1 C = 4200 mA g −1 ), which is much higher than that of bare Si spheres (430.7 mA h g −1 )

  8. A Simple Generator of Forward Scattering Functions on Spherical Dielectrics

    Directory of Open Access Journals (Sweden)

    O. Fiser

    1993-04-01

    Full Text Available The described program generates the forward scattering functions of dielectrics of spherical shape, while the input parameters are: frequency, radius of the sphere and complex refractive index. The part enabling to evaluate the complex refractive index of water in the dependence on frequency and temperature is added.

  9. Physical implication of transition voltage in organic nano-floating-gate nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shun; Gao, Xu, E-mail: wangsd@suda.edu.cn, E-mail: gaoxu@suda.edu.cn; Zhong, Ya-Nan; Zhang, Zhong-Da; Xu, Jian-Long; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn, E-mail: gaoxu@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China)

    2016-07-11

    High-performance pentacene-based organic field-effect transistor nonvolatile memories, using polystyrene as a tunneling dielectric and Au nanoparticles as a nano-floating-gate, show parallelogram-like transfer characteristics with a featured transition point. The transition voltage at the transition point corresponds to a threshold electric field in the tunneling dielectric, over which stored electrons in the nano-floating-gate will start to leak out. The transition voltage can be modulated depending on the bias configuration and device structure. For p-type active layers, optimized transition voltage should be on the negative side of but close to the reading voltage, which can simultaneously achieve a high ON/OFF ratio and good memory retention.

  10. Range measurements and track kinetics in Dielectric Nuclear Track Detectors (DNTDs)

    Energy Technology Data Exchange (ETDEWEB)

    Aframian, A

    1981-01-01

    Observations of nuclear track development profiles and the kinetics of etched tracks in sensitive dielectric nuclear track detectors indicate three separate phases: the inception phase or the cone phase, the transition phase and the sphere phase. Continued etching of the sphere phase to through-tracks yields accurate range data for particles of different masses and energies and minimum critical angles of registration for each particle. The present results show an energy resolution of 40 keV (fwhm) for 5.48 MeV alpha-particles emitted from Am-241.

  11. Investigations of Relaxation Dynamics and Observation of Nearly Constant Loss Phenomena in PEO_2_0-LiCF_3SO_3-ZrO_2 Based Polymer Nano-Composite Electrolyte

    International Nuclear Information System (INIS)

    Dam, Tapabrata; Tripathy, Satya N.; Paluch, Marian; Jena, Sidhartha S.; Pradhan, Dillip K.

    2016-01-01

    Highlights: • Ion conduction mechanism is studied using broad band dielectric spectroscopy. • Existence and cause of Nearly Constant Loss is explored. • The crossover between UDR to NCL phenomena is investigated. • Effect of filler concentration on ion transport using scaling approach is discussed. - Abstract: The conduction mechanism of polymer nano-composite electrolytes are studied using broadband dielectric spectroscopy over a wide range of frequency and temperature. The polymer nano-composites consisting of polyethylene oxide as polymer host, lithium trifluoromethanesulfonate as salt, and nano-crystalline zirconia as filler are prepared using solution casting method. Formation of polymer salt complex and nano-composites are confirmed from x-ray diffraction studies. The electrical conductivity and relaxation phenomena of the polymer salt complex as well as the composites are studied using broadband dielectric spectroscopy. At room temperature, the dc conductivity of the polymer nano-composites are found higher by two orders of magnitude than that of corresponding polymer salt complex. Temperature dependence of dc conductivity is following Vogel-Tamman-Fulcher trend, suggesting strong coupling between ionic conductivity and segmental relaxation in polymer electrolytes. Relaxation phenomena are studied with dielectric and modulus formalism. Frequency dependent ac conductivity show universal dielectric response and nearly constant loss features at high and low temperature regions respectively. The origin of universal dielectric response and nearly constant loss are analysed and discussed using different approaches. Kramer - Krönig approach suggests the origin of nearly constant loss is due to caged ion dynamics feature.

  12. Hollow magnetic nano-CO3O4/polystyrene microspheres synthesized through radiation induced interfacial polymerization

    International Nuclear Information System (INIS)

    Zhang Wei; Wang Mozhen; Wang Shufeng; Zhang Zhicheng

    2010-01-01

    Co 3 O 4 nanoparticles (around 8 nm) were synthesized hydrothermally by dissolving Co 2+ in the mixture of ethanol and water, and then decorated with oleic acid to endow them with hydrophobic surface nature. After that, nano-particles were added into emulsion which consisted by sodium dodecyl sulfate, water, styrene and cetyl alcohol. Hollow magnetic composite spheres were prepared by irradiated the emulsion with γ-rays. The final products are thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques, which showed the formation of hollow magnetic composite spheres. The influence of addition dosage of nano-particles, sodium dodecyl sulfate and the types of nano-particles on the average size and shape of hollow composites were studied. The effects of nano-particles to the polymerization of styrene were studied by kinetics. Nano-particles are capsulated by polystyrene to form hollow composites, which confirmed by XPS results. Finally, magnetic property of hollow composites is compared with pure nano-Co 3 O 4 . (authors)

  13. Environmental silicate nano-biocomposites

    CERN Document Server

    Pollet, Eric

    2012-01-01

    Environmental Silicate Nano-Biocomposites focuses on nano-biocomposites, which are obtained by the association of silicates such as bioclays with biopolymers. By highlighting recent developments and findings, green and biodegradable nano-composites from both renewable and biodegradable polymers are explored. This includes coverage of potential markets such as packaging, agricultures, leisure and the fast food industry. The knowledge and experience of more than twenty international experts in diverse fields, from chemical and biochemical engineering to applications, is brought together in four different sections covering: Biodegradable polymers and Silicates, Clay/Polyesters Nano-biocomposites, Clay/Agropolymers Nano-biocomposites, and Applications and biodegradation of Nano-biocomposites. By exploring the relationships between the biopolymer structures, the processes, and the final properties Environmental Silicate Nano-Biocomposites explains how to design nano-materials to develop new, valuable, environmenta...

  14. High-performance III-V MOSFET with nano-stacked high-k gate dielectric and 3D fin-shaped structure.

    Science.gov (United States)

    Chen, Szu-Hung; Liao, Wen-Shiang; Yang, Hsin-Chia; Wang, Shea-Jue; Liaw, Yue-Gie; Wang, Hao; Gu, Haoshuang; Wang, Mu-Chun

    2012-08-01

    A three-dimensional (3D) fin-shaped field-effect transistor structure based on III-V metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication has been demonstrated using a submicron GaAs fin as the high-mobility channel. The fin-shaped channel has a thickness-to-width ratio (TFin/WFin) equal to 1. The nano-stacked high-k Al2O3 dielectric was adopted as a gate insulator in forming a metal-oxide-semiconductor structure to suppress gate leakage. The 3D III-V MOSFET exhibits outstanding gate controllability and shows a high Ion/Ioff ratio > 105 and a low subthreshold swing of 80 mV/decade. Compared to a conventional Schottky gate metal-semiconductor field-effect transistor or planar III-V MOSFETs, the III-V MOSFET in this work exhibits a significant performance improvement and is promising for future development of high-performance n-channel devices based on III-V materials.

  15. Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles

    Directory of Open Access Journals (Sweden)

    Richard W. Ziolkowski

    2011-09-01

    Full Text Available Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles, as well as to their far-field radiation characteristics, in the presence of an electric or a magnetic line source. A constant frequency canonical gain model is used to account for the gain introduced in the dielectric part of the nano-particle, whereas three different plasmonic materials (silver, gold, and copper are employed and compared for the nano-shell layers.

  16. Micro Nano Replication Processes and Applications

    CERN Document Server

    Kang, Shinill

    2012-01-01

    This book is an introduction to the fundamentals and processes for micro and nano molding for plastic components. In addition to the basics, the book covers applications details and examples. The book helps both students and professionals to understand and work with the growing tools of molding and uses for micro and nano-sized plastic parts.Provides a comprehensive presentation on fundamentals and practices of manufacturing for micro / nano sized plastics partsCovers a relatively new but fast-growing field that is impacting any industry using plastic parts in their products (electronics, tele

  17. Branched polynomial covering maps

    DEFF Research Database (Denmark)

    Hansen, Vagn Lundsgaard

    1999-01-01

    A Weierstrass polynomial with multiple roots in certain points leads to a branched covering map. With this as the guiding example, we formally define and study the notion of a branched polynomial covering map. We shall prove that many finite covering maps are polynomial outside a discrete branch...... set. Particular studies are made of branched polynomial covering maps arising from Riemann surfaces and from knots in the 3-sphere....

  18. Porous Si spheres encapsulated in carbon shells with enhanced anodic performance in lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui; Wu, Ping, E-mail: zjuwuping@njnu.edu.cn; Shi, Huimin; Lou, Feijian; Tang, Yawen; Zhou, Tongge; Zhou, Yiming, E-mail: zhouyiming@njnu.edu.cn; Lu, Tianhong

    2014-07-01

    Highlights: • In situ magnesiothermic reduction route for the formation of porous Si@C spheres. • Unique microstructural characteristics of both porous sphere and carbon matrix. • Enhanced anodic performance in term of cycling stability for lithium-ion batteries. - Abstract: A novel type of porous Si–C micro/nano-hybrids, i.e., porous Si spheres encapsulated in carbon shells (porous Si@C spheres), has been constructed through the pyrolysis of polyvinylidene fluoride (PVDF) and subsequent magnesiothermic reduction methodology by using SiO{sub 2} spheres as precursors. The as-synthesized porous Si@C spheres have been applied as anode materials for lithium-ion batteries (LIBs), and exhibit enhanced anodic performance in term of cycling stability compared with bare Si spheres. For example, the porous Si@C spheres are able to exhibit a high reversible capacity of 900.0 mA h g{sup −1} after 20 cycles at a current density of 0.05 C (1 C = 4200 mA g{sup −1}), which is much higher than that of bare Si spheres (430.7 mA h g{sup −1})

  19. Dielectric tensor elements for the description of waves in rotating inhomogeneous magnetized plasma spheroids

    Science.gov (United States)

    Abdoli-Arani, A.; Ramezani-Arani, R.

    2012-11-01

    The dielectric permittivity tensor elements of a rotating cold collisionless plasma spheroid in an external magnetic field with toroidal and axial components are obtained. The effects of inhomogeneity in the densities of charged particles and the initial toroidal velocity on the dielectric permittivity tensor and field equations are investigated. The field components in terms of their toroidal components are calculated and it is shown that the toroidal components of the electric and magnetic fields are coupled by two differential equations. The influence of thermal and collisional effects on the dielectric tensor and field equations in the rotating plasma spheroid are also investigated. In the limiting spherical case, the dielectric tensor of a stationary magnetized collisionless cold plasma sphere is presented.

  20. Active coated nano-particle excited by an arbitrarily located electric Hertzian dipole — resonance and transparency effects

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2010-01-01

    The present work investigates the optical properties of active coated spherical nano-particles excited by an arbitrarily located electric Hertzian dipole. The nano-particles are made of specific dielectric and plasmonic materials. The spatial near-field distribution as well as the normalized...

  1. ac Conductivity analysis and dielectric relaxation behaviour of NaNO3-Al2O3 composites

    International Nuclear Information System (INIS)

    Anantha, P.S.; Hariharan, K.

    2005-01-01

    The electrical conductivity of NaNO 3 -xAl 2 O 3 composites has been studied over the wide range of temperature and frequency by means of impedance spectroscopy. The real part of the frequency dependent conductivity exhibits a simple power law feature and the dimensionless frequency exponent n has been determined. The conductivity spectra show scaling behaviour when the conductivity spectra are scaled by σ dc T, where T is temperature in Kelvin. The real part of dielectric permittivity shows saturation at higher frequencies and a strong dispersion at lower frequencies. The imaginary part of permittivity varies inversely with frequency, due to the presence of dc conductivity. The frequency dependent plots of M' and Z' show that the conductivity relaxation is non-Debye in nature. The Kohlrausch-Williams-Watts stretched exponential function was used to describe the modulus spectra and the stretching exponent β is found to be temperature independent. The conductivity relaxation time has been estimated from the modulus spectra. The activation energy responsible for relaxation has been evaluated and it was found to be almost same as that of dc conductivity

  2. YM on the dielectric brane: a D0-brane tale

    International Nuclear Information System (INIS)

    Martucci, Luca; Silva, Pedro J.

    2003-01-01

    In this letter we present a derivation, from the D0-brane picture, of the background monopole field and in general of the full dynamics of the Yang-Mills theory on the dielectric D2-brane of Myers. To do this we study the large N limit of the fuzzy sphere relevant to the dielectric solution. In contrast to the usual interpretation where the commutative D2-brane picture arises directly from the large N limit of the D0-brane picture, we find that a residual non-commutativity must be preserved in order to make the connection by means of the Seiberg-Witten map

  3. Electronic, mechanical and dielectric properties of silicane under tensile strain

    International Nuclear Information System (INIS)

    Jamdagni, Pooja; Sharma, Munish; Ahluwalia, P. K.; Kumar, Ashok; Thakur, Anil

    2015-01-01

    The electronic, mechanical and dielectric properties of fully hydrogenated silicene i.e. silicane in stable configuration are studied by means of density functional theory based calculations. The band gap of silicane monolayer can be flexibly reduced to zero when subjected to bi-axial tensile strain, leading to semi-conducting to metallic transition, whereas the static dielectric constant for in-plane polarization increases monotonically with increasing strain. Also the EEL function show the red shift in resonance peak with tensile strain. Our results offer useful insight for the application of silicane monolayer in nano-optical and electronics devices

  4. Anticancer effects of Bilberry anthocyanins compared with NutraNanoSphere encapsulated Bilberry anthocyanins.

    Science.gov (United States)

    Thibado, Seth P; Thornthwaite, Jerry T; Ballard, Thomas K; Goodman, Brandon T

    2018-02-01

    Rapidly accumulating laboratory and clinical research evidence indicates that anthocyanins exhibit anticancer activity and the evaluation of bilberry anthocyanins as chemo-preventive agents is progressing. It has previously been demonstrated that anthocyanins upregulate tumor suppressor genes, induce apoptosis in cancer cells, repair and protect genomic DNA integrity, which is important in reducing age-associated oxidative stress, and improve neuronal and cognitive brain function. Bilberry anthocyanins have pronounced health effects, even though they have a low bioavailability. To increase the bioavailability, Bilberry was encapsulated in 5.5 nm diameter liposomal micelles, called NutraNanoSpheres (NNS), at a concentration of 2.5 mg/50 µl [25% (w/w) anthocyanins]. These Bilberry NNS were used to study the apoptotic/cytotoxic effects on K562 Human Erythroleukemic cancer cells. Flow cytometric fluorescent quantification of the uptake of propidium iodide in a special cell viability formulation into dead K562 cells was used to determine the effects of Bilberry on the viability of K562 cells. The concentrations of Bilberry that demonstrated the greatest levels of percentage inhibition, relative to the control populations, were biphasic, revealing a 60-70% inhibition between 0.018-1.14 mg/ml (n=6) and 60% inhibition at 4 mg/ml. The lowest percentage inhibition (30%) occurred at 2 mg/ml. The lethal dose 50 was determined to be 0.01-0.04 mg/ml of Bilberry per 105 K562 cells at 72 h of cell culture exposure. At 48 h incubation, the highest percentage of inhibition was only 27%, suggesting involvement of a long-term apoptotic event. These levels, which demonstrated direct cytotoxic effects, were 8-40 times lower than levels required for Bilberry that is not encapsulated. The increase in bioavailability with the Bilberry NNS and its water solubility demonstrated the feasibility of using Bilberry NNS in cancer patient clinical trials.

  5. Structural, magnetic and dielectric investigations in antimony doped nano-phased nickel-zinc ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, Ch.S. [Department of Physics, Regency Institute of Technology, Adivipolam Yanam 533464, Pondicherry (India); Sridhar, Ch.S.L.N. [Department of Physics, Vignana Bharathi Institute of Technology, Aushapur(v) Ghatkesar (M), Hyderabad 501301, Telangana (India); Govindraj, G. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V.Nagar, Kalapet, Pondicherry 605014 (India); Bangarraju, S. [Department of Physics, Andhra University, Visakhapatnam 530003, Andhrapradesh (India); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University:Kakinada, Kakinada 533003 (India)

    2015-02-15

    Nanocrystalline Ni–Zn–Sb ferrites synthesized by hydrothermal method are reported. Influence of Sb{sup 5+} ions on structural, magnetic and dielectric properties of ferrites is studied. Phase identification, lattice parameter and crystallite size studies are carried out using by X-ray diffraction (XRD). Addition of dopant resulted for decrease in lattice parameter. Crystallite size gets reduced from 62 nm to 38 nm with doping of Antimony. Crystallite size and porosity exhibit similar trends with doping. Morphological study is carried out by Field Emission Scanning Electron Microscopy (FESEM). Strong FTIR absorption bands at 400–600 cm{sup −1} confirm the formation of ferrite structure. Increase of porosity is attributed to the grain size. Doping with Antimony results for decrease in saturation magnetization and increase in coercivity. An initial increase of saturation magnetization for x=0.1 is attributed to the unusually high density. Reversed trend of coercivity with crystallite size are observed. Higher value of dielectric constant ε′(ω) is attributed to the formation of excess of Fe{sup 2+} ions caused by aliovalent doping of Sb{sup 5+} ions. Variation of dielectric constant infers hopping type of conductivity mechanism. The dielectric loss factor tanδ attains lower values of ∼10{sup −2}. High ac resistivity ρ(ω) of 10{sup 8} Ω cm is witnessed for antimony doped ferrites. Higher saturation magnetization and enhanced dielectric response directs for a possible utility as microwave oscillators and switches.

  6. VMware vSphere 5.1 cookbook

    CERN Document Server

    GB, Abhilash

    2013-01-01

    A fast-paced, task-oriented Cookbook covering recipes on the installation and configuration of vSphere 5.1 components. The recipes are accompanied with relevant screenshots with an intention to provide a visual guidance as well. The book concentrates more on the actual task rather than the theory around it, making it easier to understand what is really needed to achieve the task.This book is a guide for anyone who wants to learn how to install and configure VMware vSphere components. This is an excellent handbook for support professionals or for anyone intending to give themselves a head start

  7. Investigation of the correlation between dielectric function, thickness and morphology of nano-granular ZnO very thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gilliot, Mickaël, E-mail: mickael.gilliot@univ-reims.fr [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Hadjadj, Aomar [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Martin, Jérôme [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Université de Technologie de Troyes (France)

    2015-12-31

    Thin nano-granular ZnO layers were prepared using a sol–gel synthesis and spin-coating deposition process with a thickness ranging between 20 and 120 nm. The complex dielectric function (ϵ) of the ZnO film was determined from spectroscopic ellipsometry measurements. Up to a critical thickness close to 60 nm, the magnitude of both the real and the imaginary parts of ϵ rapidly increases and then slowly tends to values closer to the bulk ZnO material. This trend suggests a drastic change in the film porosity at both sides of this critical thickness, due to the pre-heating and post-crystallization processes, as confirmed by additional characterization of the structure and the morphology of the ZnO films. - Highlights: • c-Axis oriented ZnO thin films were grown with different morphological states. • The morphology and structures are controlled by controlling the thickness. • The optical properties are correlated to morphological evolution. • Two growth behaviors and property evolutions are identified around a critical thickness.

  8. Legal issues of the environmental safety regulation in the sphere of nanotechnology in Russian Federation

    International Nuclear Information System (INIS)

    Belokrylova, Ekaterina A

    2013-01-01

    Nowadays one of the principal innovative spheres in Russia is considered to be a rapid development of nanotechnology and nanomaterials and implementation its products into almost all fields of social and industrial life. Nevertheless, despite the pointed advantages an appearance of nano products has set not only a positive example of the scientific progress development and dynamics, but also a potential threat of possible risks for the environment and people's health in the case of its massive use when there is a lack of research about its impacts. In Russian Federation the problem of nanosafety regulation is extremely actual. A number of international documents have noted a lack of legal regulation in the sphere of nanotechnologies in Russian Federation. Thus, according to the strategic EU program, it's mentioned that in 2009 on an annual meeting of OECD Tour de Table Meeting in Paris (November, 2007) Russia took responsibility to develop a long term program of nanoindustry development by 2015 (Nanotechnology Action Plan for Russia-2015). The key role should be dedicated to the nanosafety aspects and potential risk assessment of nanomaterials for environment and humans' health. Unfortunately, until now Russia did not provide this document for discussion at the international level by the partners of nanoconsortcium. Indeed, from 2007 until nowadays in Russian Federation there are no a single federal act of legislation (federal'nyi zakon), establishing the state foundations of regulation of nanosafety. The only one Federeal Legal Act in the described sphere is the Federalniy Zakon from 19 July 2007 A bout the Russian corporation of nanotechnologies , which has established the principles of organization, activites, functions and termination of Rosnanotech. However, there are no articles dedicated to the environmental safety provision in regards of nano products applications. Also there is no complex federal act consolidating legal status of action in the field of

  9. Legal issues of the environmental safety regulation in the sphere of nanotechnology in Russian Federation

    Science.gov (United States)

    Belokrylova, Ekaterina A.

    2013-04-01

    Nowadays one of the principal innovative spheres in Russia is considered to be a rapid development of nanotechnology and nanomaterials and implementation its products into almost all fields of social and industrial life. Nevertheless, despite the pointed advantages an appearance of nano products has set not only a positive example of the scientific progress development and dynamics, but also a potential threat of possible risks for the environment and people's health in the case of its massive use when there is a lack of research about its impacts. In Russian Federation the problem of nanosafety regulation is extremely actual. A number of international documents have noted a lack of legal regulation in the sphere of nanotechnologies in Russian Federation. Thus, according to the strategic EU program, it's mentioned that in 2009 on an annual meeting of OECD Tour de Table Meeting in Paris (November, 2007) Russia took responsibility to develop a long term program of nanoindustry development by 2015 (Nanotechnology Action Plan for Russia-2015). The key role should be dedicated to the nanosafety aspects and potential risk assessment of nanomaterials for environment and humans' health. Unfortunately, until now Russia did not provide this document for discussion at the international level by the partners of nanoconsortcium. Indeed, from 2007 until nowadays in Russian Federation there are no a single federal act of legislation (federal'nyi zakon), establishing the state foundations of regulation of nanosafety. The only one Federeal Legal Act in the described sphere is the Federalniy Zakon from 19 July 2007 "About the Russian corporation of nanotechnologies", which has established the principles of organization, activites, functions and termination of Rosnanotech. However, there are no articles dedicated to the environmental safety provision in regards of nano products applications. Also there is no complex federal act consolidating legal status of action in the field of

  10. The sphere-PAC fuel code 'SPHERE-3'

    International Nuclear Information System (INIS)

    Wallin, H.

    2000-01-01

    Sphere-PAC fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-PAC fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  11. The sphere-pac fuel code 'SPHERE-3'

    International Nuclear Information System (INIS)

    Wallin, H.; Nordstroem, L.A.; Hellwig, C.

    2001-01-01

    Sphere-pac fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-pac fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  12. Direct deposition of aluminum oxide gate dielectric on graphene channel using nitrogen plasma treatment

    International Nuclear Information System (INIS)

    Lim, Taekyung; Kim, Dongchool; Ju, Sanghyun

    2013-01-01

    Deposition of high-quality dielectric on a graphene channel is an essential technology to overcome structural constraints for the development of nano-electronic devices. In this study, we investigated a method for directly depositing aluminum oxide (Al 2 O 3 ) on a graphene channel through nitrogen plasma treatment. The deposited Al 2 O 3 thin film on graphene demonstrated excellent dielectric properties with negligible charge trapping and de-trapping in the gate insulator. A top-gate-structural graphene transistor was fabricated using Al 2 O 3 as the gate dielectric with nitrogen plasma treatment on graphene channel region, and exhibited p-type transistor characteristics

  13. Dopant driven tunability of dielectric relaxation in MxCo(1-x)Fe2O4 (M: Zn2+, Mn2+, Ni2+) nano-ferrites

    Science.gov (United States)

    Datt, Gopal; Abhyankar, A. C.

    2017-07-01

    Nano-ferrites with tunable dielectric and magnetic properties are highly desirable in modern electronics industries. This work reports the effect of ferromagnetic (Ni), anti-ferromagnetic (Mn), and non-magnetic (Zn) substitution on cobalt-ferrites' dielectric and magnetic properties. The Rietveld analysis of XRD data and the Raman spectroscopic study reveals that all the samples are crystallized in the Fd-3m space group. The T2g Raman mode was observed to split into branches, which is due to the presence of different cations (with different vibrational frequencies) at crystallographic A and B-sites. The magnetization study shows that the MnCoFe2O4 sample has the highest saturation magnetization of 87 emu/g, which is attributed to the presence of Mn2+ cations at the B-site with a magnetic moment of 5 μB. The dielectric permittivity of these nanoparticles (NPs) obeys the modified Debye model, which is further supported by Cole-Cole plots. The dielectric constant of MnCoFe2O4 ferrite is found to be one order higher than that of the other two ferrites. The increased bond length of the Mn2+-O2- bond along with the enhanced d-d electron transition between Mn 2 +/Co 2 +⇋Fe 3 + cations at the B-site are found to be the main contributing factors for the enhanced dielectric constant of MnCoFe2O4 ferrite. We find evidence of variable-range hopping of localized polarons in these ferrite NPs. The activation energy, hopping range, and density of states N (" separators="|EF ), of these polarons were calculated using Motts' 1/4th law. The estimated activation energies of these polarons at 300 K were found to be 288 meV, 426 meV, and 410 meV, respectively, for the MnCoFe2O4, NiCoFe2O4, and ZnCoFe2O4 ferrite NPs, while the hopping range of these polarons were found to be 27.14 Å, 11.66 Å, and 8.17 Å, respectively. Observation of a low dielectric loss of ˜0.04, in the frequency range of 0.1-1 MHz, in these NPs makes them potential candidates for energy harvesting devices in

  14. Nonlinear super-resolution nano-optics and applications

    CERN Document Server

    Wei, Jingsong

    2015-01-01

    This book covers many advances in the subjects of nano-optics and nano photonics. The author describes the principle and technical schematics of common methods for breaking through the optical diffraction limit and focuses on realizing optical super-resolution with nonlinear effects of thin film materials. The applications of nonlinear optical super-resolution effects in nano-data storage, nanolithography, and nano-imaging are also presented. This book is useful to graduate students majoring in optics and nano science and also serves as a reference book for academic researchers, engineers, technical professionals in the fields of super-resolution optics and laser techniques, nano-optics and nano photonics, nano-data storage, nano imaging, micro/nanofabrication and nanolithography and nonlinear optics.

  15. Structural, Magnetic, and Transport Properties of Polymer-Nano ferrite Composites

    International Nuclear Information System (INIS)

    Imam, N.G.G.

    2013-01-01

    In this work, a series of (x) BaTiO 3 / (1-x) Ni 0.5 Zn 0.5 Fe 2 O 4 nano composite samples were prepared using citrate auto combustion and the samples were classified into three groups.In first group: A series of (x) BaTiO 3 / (1-x) Ni 0.5 Zn 0.5 Fe 2 O 4 ; 0.0≤ x ≤ 1.0 were prepared by double sintering technique and citrate auto combustion method in comparison study due to different characterization analysis. The comparison reveals that from X-ray diffraction; all the samples from the two methods formed in single phase in both; cubic spinel structure NiZnFe 2 O 4 (NZF) ferrite and perovskite tetragonal structure BaTiO 3 (BTO).In group two, in another compassion, multiferroic hybrid nano composites based on different polymers as a matrix for the prepared magnetoelectric biferroic nano composite system 0.5 BaTiO 3 / 0.5Ni 0.5 Zn 0.5 Fe 2 O 4 that has been prepared by citrate auto combustion method. Four different polymers namely poly aniline (PANI), polyvinyl acetate (PVAc), Polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG), with fixed ration (1:1) with respect to the dispersed magnetoelectric nano composite.In group three, the nano composites materials with formula (1-y) [0.5 BaTiO 3 / 0.5 Ni 0.5 Zn 0.5 Fe 2 O 4 ] / (y) (PEG); 0.0 ≤y ≤+ 1.0, have been prepared at room temperature by weight mixing and cold pressing. Physical properties of nano composite materials consisting different ratios of polyethylene glycol were investigated. With the variation of y content, typical magnetic hysteresis loops of nano composites have been observed in the nano composites at room temperature. When PEG content increase, the saturation magnetization decrease. Meanwhile, the coercive force tends to stable. Additionally, the dielectric constant (ε ' ) and dielectric loss factor (ε '' ) of nano composites materials shift toward higher frequency. The value of (ε ' ) decreased with increasing frequency, which indicates that the major contribution

  16. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Joy, Lija K.; Sooraj, V.; Sethulakshmi, N.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin-682022, Kerala (India); Sajeev, U. S. [Department of Physics, Government College, Kottayam-686613, Kerala (India); Nair, Swapna S. [Department of Physics, School of Mathematical and Physical Sciences, Central University of Kerala, Kasargode-671123, Kerala (India); Narayanan, T. N. [CSIR-Central Electrochemical Research Institute, Karaikkudi-630006, Tamil Nadu (India); Ajayan, P. M. [Department of Material Science and Nano Engineering, Rice University, 6100 Main Street, Houston, Texas 7700 (United States)

    2014-03-24

    Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed.

  17. Dielectric properties study of surface engineered nanoTiO2/epoxy ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... 2Department of Physics, Sri Sathya Sai Institute of Higher Learning, Vidyagiri, ... the surface modifiers were not successful in obtaining the improved dielectric .... lent Technologies Inc., Santa Clara, CA) at a frequency range.

  18. Linear and ultrafast nonlinear plasmonics of single nano-objects

    Science.gov (United States)

    Crut, Aurélien; Maioli, Paolo; Vallée, Fabrice; Del Fatti, Natalia

    2017-03-01

    Single-particle optical investigations have greatly improved our understanding of the fundamental properties of nano-objects, avoiding the spurious inhomogeneous effects that affect ensemble experiments. Correlation with high-resolution imaging techniques providing morphological information (e.g. electron microscopy) allows a quantitative interpretation of the optical measurements by means of analytical models and numerical simulations. In this topical review, we first briefly recall the principles underlying some of the most commonly used single-particle optical techniques: near-field, dark-field, spatial modulation and photothermal microscopies/spectroscopies. We then focus on the quantitative investigation of the surface plasmon resonance (SPR) of metallic nano-objects using linear and ultrafast optical techniques. While measured SPR positions and spectral areas are found in good agreement with predictions based on Maxwell’s equations, SPR widths are strongly influenced by quantum confinement (or, from a classical standpoint, surface-induced electron scattering) and, for small nano-objects, cannot be reproduced using the dielectric functions of bulk materials. Linear measurements on single nano-objects (silver nanospheres and gold nanorods) allow a quantification of the size and geometry dependences of these effects in confined metals. Addressing the ultrafast response of an individual nano-object is also a powerful tool to elucidate the physical mechanisms at the origin of their optical nonlinearities, and their electronic, vibrational and thermal relaxation processes. Experimental investigations of the dynamical response of gold nanorods are shown to be quantitatively modeled in terms of modifications of the metal dielectric function enhanced by plasmonic effects. Ultrafast spectroscopy can also be exploited to unveil hidden physical properties of more complex nanosystems. In this context, two-color femtosecond pump-probe experiments performed on individual

  19. Dielectric studies of Graphene and Glass Fiber reinforced composites

    Science.gov (United States)

    Praveen, D.; Shashi Kumar, M. E.; Pramod, R.

    2018-02-01

    Graphene and E-glass fibres are one of the key materials used currently due to their unique chemical and mechanical properties. Lately graphene has attracted many researchers across academic fraternity as it can yield better properties with lesser reinforcement percentages. The current research emphasizes on the development of graphene-based nanocomposites and its investigation on dielectric applications. The composites were fabricated by adding graphene reinforcements from 1%-3% by weight using conventional Hand-lay process. A thorough investigation was carried out to determine the dielectric behaviour of the nano-composites using impedance analyser according to ASTM standards. The dielectric measurements were carried out in the temperature range of 300K to 400K in a step of 20K. The current research proposes the material for application in capacitor industry as the sample of 2.5% weight fraction showed highest value of K with 14 at 26.1 Hz and 403K.

  20. Statistical mechanics of molecular fluids. The RHNC theory applied to hard dipolar spheres

    International Nuclear Information System (INIS)

    Lombardero, M.; Lado, F.; Abascal, J.L.F.; Lago, S.; Enciso, E.

    1988-01-01

    The RHNC (reference hipernetted chain) equation, together with an optimization criterion which extremalizes the Helmholtz free energy, is used to obtain structural, thermodynamic, and dielectric properties of a system made up of hard dipolar spheres. The comparison with simulation results is made in the same boundary conditions and then the properties of an infinite system are evaluated for a variaty of states at different densities and dipolar moments. (Author)

  1. Fabrication of three-dimensional MIS nano-capacitor based on nano-imprinted single crystal silicon nanowire arrays

    KAUST Repository

    Zhai, Yujia

    2012-11-26

    We report fabrication of single crystalline silicon nanowire based-three-dimensional MIS nano-capacitors for potential analog and mixed signal applications. The array of nanowires is patterned by Step and Flash Imprint Lithography (S-FIL). Deep silicon etching (DSE) is used to form the nanowires with high aspect ratio, increase the electrode area and thus significantly enhance the capacitance. High-! dielectric is deposited by highly conformal atomic layer deposition (ALD) Al2O3 over the Si nanowires, and sputtered metal TaN serves as the electrode. Electrical measurements of fabricated capacitors show the expected increase of capacitance with greater nanowire height and decreasing dielectric thickness, consistent with calculations. Leakage current and time-dependent dielectric breakdown (TDDB) are also measured and compared with planar MIS capacitors. In view of greater interest in 3D transistor architectures, such as FinFETs, 3D high density MIS capacitors offer an attractive device technology for analog and mixed signal applications. - See more at: http://www.eurekaselect.com/105099/article#sthash.EzeJxk6j.dpuf

  2. Fabrication of three-dimensional MIS nano-capacitor based on nano-imprinted single crystal silicon nanowire arrays

    KAUST Repository

    Zhai, Yujia; Palard, Marylene; Mathew, Leo; Hussain, Muhammad Mustafa; Willson, Grant Grant; Tutuc, Emanuel; Banerjee, Sanjay Kumar

    2012-01-01

    We report fabrication of single crystalline silicon nanowire based-three-dimensional MIS nano-capacitors for potential analog and mixed signal applications. The array of nanowires is patterned by Step and Flash Imprint Lithography (S-FIL). Deep silicon etching (DSE) is used to form the nanowires with high aspect ratio, increase the electrode area and thus significantly enhance the capacitance. High-! dielectric is deposited by highly conformal atomic layer deposition (ALD) Al2O3 over the Si nanowires, and sputtered metal TaN serves as the electrode. Electrical measurements of fabricated capacitors show the expected increase of capacitance with greater nanowire height and decreasing dielectric thickness, consistent with calculations. Leakage current and time-dependent dielectric breakdown (TDDB) are also measured and compared with planar MIS capacitors. In view of greater interest in 3D transistor architectures, such as FinFETs, 3D high density MIS capacitors offer an attractive device technology for analog and mixed signal applications. - See more at: http://www.eurekaselect.com/105099/article#sthash.EzeJxk6j.dpuf

  3. On the nature of the nanospikes obtained in the sonication of a molten mixture of bismuth and indium under silicone oil

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay Bhooshan [Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); Ezersky, Vladimir [Ilse Katz Institute of Nanoscale Science and Technology, Ben-Gurion University of the Negev, Be' er Sheva 84105 (Israel); Gedanken, Aharon, E-mail: gedanken@mail.biu.ac.il [Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); National Cheng Kung University, Department of Materials Science & Engineering, Tainan 70101, Taiwan, ROC (China); Porat, Ze' ev, E-mail: poratze@post.bgu.ac.il [Division of Chemistry, Nuclear Research Center-Negev, P.O.Box 9001, Be' er-Sheva 84190 (Israel); Institutes of Applied Research, Ben-Gurion University of the Negev, Be' er-Sheva 84105 (Israel)

    2016-07-05

    A molten mixture of bismuth and indium, immersed in hot silicone oil, was dispersed into nano- and micro spheres under ultrasonic irradiation. Examination of the composition of these spheres by X-ray diffraction and Rietveld refinement revealed that they were composed of intermetallic compounds, mainly BiIn and BiIn{sub 2}. TEM and SEM images showed that the surface of the spheres was covered with tiny spikes. Their chemical composition, as determined by EDS and electron diffraction, was found to be In{sub 2}O{sub 3}. We assume that upon formation they were composed of In, which was oxidized when exposed to air. - Highlights: • Ultrasonication of molten Bi–In caused dispersion into nano- and micro spheres. • The spheres were composed of intermetallic compounds, mainly BiIn and BiIn{sub 2}. • The spheres' surface was covered with tiny spikes. • The composition of the spikes was determined by EDS and ED to be In{sub 2}O{sub 3}. • Upon formation the spikes were composed of In, which was oxidized by air.

  4. Photonic nanojet super-resolution in immersed ordered assembly of dielectric microspheres

    International Nuclear Information System (INIS)

    Geints, Y.E.; Zemlyanov, A.A.

    2017-01-01

    Highlights: • Ordered microassemblies of dielectric microspheres immersed in a transparent matrix exposed to a light wave produce an array of the “photonic nanojets” coupled through the field interference. • “Photonic nanojet” parameters depend on the inter-sphere gap and immersion depth. • Sphere microassembly can produce the jets with the sub-diffraction spatial resolution if the particles are loosely packed and semi-immersed. - Abstract: Specific spatially-localized optical field structure, which is often referred to as a photonic nanojet (PNJ), is formed in the near-field scattering area of non-absorbing dielectric micron-sized particle exposed to an optical radiation. By virtue of the finite-difference time-domain technique we numerically simulate the two-dimensional array of PNJs created by an ordered single-layer microassembly of glass microspheres immersed in a transparent polymer matrix. The behavior of the main PNJ parameters (length, diameter, and intensity) is analyzed subject to the immersion depth of the microparticles and cooperative interference effects of the neighboring microspheres. We show that depending on microassembly configuration, the PNJ quality can be significantly improved; in particular, the PNJ spatial resolution better than λ/5 can be achieved.

  5. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander; Hö binger, Mathias; Wallner, Johannes; Pottmann, Helmut

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

  6. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-12-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

  7. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

  8. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander; Hö binger, Mathias; Wallner, Johannes; Pottmann, Helmut

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

  9. Crystallization in nano-confinement seeded by a nanocrystal—A molecular dynamics study

    KAUST Repository

    Pan, Heng; Grigoropoulos, Costas

    2014-01-01

    Seeded crystallization and solidification in nanoscale confinement volumes have become an important and complex topic. Due to the complexity and limitations in observing nanoscale crystallization, computer simulation can provide valuable details for supporting and interpreting experimental observations. In this article, seeded crystallization from nano-confined liquid, as represented by the crystallization of a suspended gold nano-droplet seeded by a pre-existing gold nanocrystal seed, was investigated using molecular dynamics simulations in canonical (NVT) ensemble. We found that the crystallization temperature depends on nano-confinement volume, crystal orientation, and seed size as explained by classical two-sphere model and Gibbs-Thomson effect. © 2014 AIP Publishing LLC.

  10. Crystallization in nano-confinement seeded by a nanocrystal—A molecular dynamics study

    KAUST Repository

    Pan, Heng

    2014-03-14

    Seeded crystallization and solidification in nanoscale confinement volumes have become an important and complex topic. Due to the complexity and limitations in observing nanoscale crystallization, computer simulation can provide valuable details for supporting and interpreting experimental observations. In this article, seeded crystallization from nano-confined liquid, as represented by the crystallization of a suspended gold nano-droplet seeded by a pre-existing gold nanocrystal seed, was investigated using molecular dynamics simulations in canonical (NVT) ensemble. We found that the crystallization temperature depends on nano-confinement volume, crystal orientation, and seed size as explained by classical two-sphere model and Gibbs-Thomson effect. © 2014 AIP Publishing LLC.

  11. WebSphere Application Server Step by Step

    CERN Document Server

    Cline, Owen; Van Sickel, Peter

    2012-01-01

    WebSphere Application Server (WAS) is complex and multifaceted middleware used by huge enterprises as well as small businesses. In this book, the authors do an excellent job of covering the many aspects of the software. While other books merely cover installation and configuration, this book goes beyond that to cover the critical verification and management process to ensure a successful installation and implementation. It also addresses all of the different packages-from Express to Network-so that no matter what size your company is, you will be able to successfully implement WAS V6. To de

  12. High Dielectric Low Loss Transparent Glass Material Based Dielectric Resonator Antenna with Wide Bandwidth Operation

    Science.gov (United States)

    Mehmood, Arshad; Zheng, Yuliang; Braun, Hubertus; Hovhannisyan, Martun; Letz, Martin; Jakoby, Rolf

    2015-01-01

    This paper presents the application of new high permittivity and low loss glass material for antennas. This glass material is transparent. A very simple rectangular dielectric resonator antenna is designed first with a simple microstrip feeding line. In order to widen the bandwidth, the feed of the design is modified by forming a T-shaped feeding. This new design enhanced the bandwidth range to cover the WLAN 5 GHz band completely. The dielectric resonator antenna cut into precise dimensions is placed on the modified microstrip feed line. The design is simple and easy to manufacture and also very compact in size of only 36 × 28 mm. A -10 dB impedance bandwidth of 18% has been achieved, which covers the frequency range from 5.15 GHz to 5.95 GHz. Simulations of the measured return loss and radiation patterns are presented and discussed.

  13. Influence of Reactive Ion Etching on THz Transmission and Reflection Properties of NiCr Film Deposited on a Dielectric Substrate

    Directory of Open Access Journals (Sweden)

    Jun Gou

    2015-06-01

    Full Text Available Enhanced terahertz (THz absorption of NiCr film deposited on a dielectric substrate has been proven by applying a reactive ion etching (RIE treatment to the dielectric film. Nano – scale nickel – chromium (NiCr thin films are deposited on RIE treated silicon dioxide (SiO2 dielectric substrates to study the transmission and reflection characteristics. Experimental results suggest that both transmission and reflection of NiCr film are weakened by the RIE treatment. The most significant decrease of transmission is observed in 1 ~ 4 THz while that of reflection occurs in 1.7 ~ 2.5 THz band. The decrease of both transmission and reflection is more significant for NiCr film with higher thickness. The RIE treatment, which induces nano – scale surface structures and increases the effective surface area of NiCr film, enhances the absorption and weakens the transmission and reflection of THz radiation.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6131

  14. Branched polynomial covering maps

    DEFF Research Database (Denmark)

    Hansen, Vagn Lundsgaard

    2002-01-01

    A Weierstrass polynomial with multiple roots in certain points leads to a branched covering map. With this as the guiding example, we formally define and study the notion of a branched polynomial covering map. We shall prove that many finite covering maps are polynomial outside a discrete branch ...... set. Particular studies are made of branched polynomial covering maps arising from Riemann surfaces and from knots in the 3-sphere. (C) 2001 Elsevier Science B.V. All rights reserved.......A Weierstrass polynomial with multiple roots in certain points leads to a branched covering map. With this as the guiding example, we formally define and study the notion of a branched polynomial covering map. We shall prove that many finite covering maps are polynomial outside a discrete branch...

  15. Metamaterial-based theoretical description of light scattering by metallic nano-hole array structures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Najiminaini, Mohamadreza; Carson, Jeffrey J. L. [Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada); Balakrishnan, Shankar [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada)

    2015-05-14

    We have experimentally and theoretically investigated the light-matter interaction in metallic nano-hole array structures. The scattering cross section spectrum was measured for three samples each having a unique nano-hole array radius and periodicity. Each measured spectrum had several peaks due to surface plasmon polaritons. The dispersion relation and the effective dielectric constant of the structure were calculated using transmission line theory and Bloch's theorem. Using the effective dielectric constant and the transfer matrix method, the surface plasmon polariton energies were calculated and found to be quantized. Using these quantized energies, a Hamiltonian for the surface plasmon polaritons was written in the second quantized form. Working with the Hamiltonian, a theory of scattering cross section was developed based on the quantum scattering theory and Green's function method. For both theory and experiment, the location of the surface plasmon polariton spectral peaks was dependant on the array periodicity and radii of the nano-holes. Good agreement was observed between the experimental and theoretical results. It is proposed that the newly developed theory can be used to facilitate optimization of nanosensors for medical and engineering applications.

  16. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    International Nuclear Information System (INIS)

    Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

    2010-01-01

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  17. VMware vSphere performance designing CPU, memory, storage, and networking for performance-intensive workloads

    CERN Document Server

    Liebowitz, Matt; Spies, Rynardt

    2014-01-01

    Covering the latest VMware vSphere software, an essential book aimed at solving vSphere performance problems before they happen VMware vSphere is the industry's most widely deployed virtualization solution. However, if you improperly deploy vSphere, performance problems occur. Aimed at VMware administrators and engineers and written by a team of VMware experts, this resource provides guidance on common CPU, memory, storage, and network-related problems. Plus, step-by-step instructions walk you through techniques for solving problems and shed light on possible causes behind the problems. Divu

  18. The sphere-PAC fuel code 'SPHERE-3'

    Energy Technology Data Exchange (ETDEWEB)

    Wallin, H

    2000-07-01

    Sphere-PAC fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-PAC fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  19. The influence of Span-20 surfactant and micro-/nano-Chromium (Cr) Powder Mixed Electrical Discharge Machining (PMEDM) on the surface characteristics of AISI D2 hardened steel

    Science.gov (United States)

    Hosni, N. A. J.; Lajis, M. A.

    2018-04-01

    The application of powder mixed dielectric to improve the efficiency of electrical discharge machining (EDM) has been extensively studied. Therefore, PMEDM have attracted the attention of many researchers since last few decades. Improvement in EDM process has resulted in the use of span-20 surfactant and Cr powder mixed in dielectric fluid, which results in increasing machiniability, better surface quality and faster machining time. However, the study of powder suspension size of surface charateristics in EDM field is still limited. This paper presents the improvement of micro-/nano- Cr powder size on the surface characteristics of the AISI D2 hardened steels in PMEDM. It has found that the reacst layer in PMEDM improved by as high as 41-53 % compared to conventional EDM. Also notably, the combination of added Cr powder and span-20 surfactant reduced the recast layer thickness significantly especially in nano-Cr size. This improvement was great potential adding nano-size Cr powder to dielectric for machining performance.

  20. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    OpenAIRE

    Abdalla, Soliman; Al-Marzouki, Fahad; Obaid, Abdullah; Gamal, Salah

    2016-01-01

    Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of...

  1. Triassico: A Sphere Positioning System for Surface Studies with IBA Techniques

    Science.gov (United States)

    Fontana, Cristiano L.; Doyle, Barney L.

    We propose here a novel device, called the Triassico, to microscopically study the entire surface of millimeter-sized spheres. The sphere dimensions can be as small as 1 mm, and the upper limit defined only by the power and by the mechanical characteristics of the motors used. Three motorized driving rods are arranged so an equilateral triangle is formed by the rod's axes, on such a triangle the sphere sits. Movement is achieved by rotating the rods with precise relative speeds and by exploiting the friction between the sphere and the rods surfaces. The sphere can be held in place by gravity or by an opposing trio of rods. By rotating the rods with specific relative angular velocities, a net torque can be exerted on the sphere which then rotates. No repositioning of the sphere or of the motors is needed to cover the full surface with the investigating tools. An algorithm was developed to position the sphere at any arbitrary polar and azimuthal angle. The algorithm minimizes the number of rotations needed by the rods, in order to efficiently select a particular position on the sphere surface. A prototype Triassico was developed for the National Ignition Facility, of the Lawrence Livermore National Laboratory (Livermore, California, USA), as a sphere manipulation apparatus for ion microbeam analysis at Sandia National Laboratories (Albuquerque, NM, USA) of Xe-doped DT inertial confinement fusion fuel spheres. Other applications span from samples orientation, ball bearing manufacturing, or jewelry.

  2. The onset of cavitation during the collision of a sphere with a wetted surface

    KAUST Repository

    Mansoor, Mohammad M.; Uddin, Jamal; Marston, Jeremy; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur T

    2014-01-01

    We investigate the onset of cavitation during the collision of a sphere with a solid surface covered with a layer of Newtonian liquid. The conventional theory dictates cavitation to initiate during depressurization, i.e. when the sphere rebounds from the solid surface. Using synchronized dual-view high-speed imaging, we provide conclusive experimental evidence that confirms this scenario- namely-that cavitation occurs only after the sphere makes initial contact with the solid surface. Similar to previous experimental observations for spheres released above the liquid surface, bubbles are formed on the sphere surface during entry into the liquid layer. These were found to squeeze radially outwards with the liquid flow as the sphere approached the solid surface, producing an annular bubble structure unrelated to cavitation. In contrast, spheres released below the liquid surface did not exhibit these patterns. © Springer-Verlag Berlin Heidelberg 2014.

  3. Effect of TMAH Etching Duration on the Formation of Silicon Nano wire Transistor Patterned by AFM Nano lithography

    International Nuclear Information System (INIS)

    Hutagalung, S.D.; Lew, K.C.

    2012-01-01

    Atomic force microscopy (AFM) lithography was applied to produce nano scale pattern for silicon nano wire transistor fabrication. This technique takes advantage of imaging facility of AFM and the ability of probe movement controlling over the sample surface to create nano patterns. A conductive AFM tip was used to grow the silicon oxide nano patterns on silicon on insulator (SOI) wafer. The applied tip-sample voltage and writing speed were well controlled in order to form pre-designed silicon oxide nano wire transistor structures. The effect of tetra methyl ammonium hydroxide (TMAH) etching duration on the oxide covered silicon nano wire transistor structure has been investigated. A completed silicon nano wire transistor was obtained by removing the oxide layer via hydrofluoric acid etching process. The fabricated silicon nano wire transistor consists of a silicon nano wire that acts as a channel with source and drain pads. A lateral gate pad with a nano wire head was fabricated very close to the channel in the formation of transistor structures. (author)

  4. A review of nano-optics in metamaterial hybrid heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, Western University, London N6G 3K7 (Canada)

    2014-03-31

    We present a review for the nonlinear nano-optics in quantum dots doped in a metamaterial heterostructure. The heterostructure is formed by depositing a metamaterial on a dielectric substrate and ensemble of noninteracting quantum dots are doped near the heterostructure interface. It is shown that there is enhancement of the second harmonic generation due to the surface plasmon polaritons field present at the interface.

  5. Investigation of 6T SRAM memory circuit using high-k dielectrics based nano scale junctionless transistor

    Science.gov (United States)

    Charles Pravin, J.; Nirmal, D.; Prajoon, P.; Mohan Kumar, N.; Ajayan, J.

    2017-04-01

    In this paper the Dual Metal Surround Gate Junctionless Transistor (DMSGJLT) has been implemented with various high-k dielectric. The leakage current in the device is analysed in detail by obtaining the band structure for different high-k dielectric material. It is noticed that with increasing dielectric constant the device provides more resistance for the direct tunnelling of electron in off state. The gate oxide capacitance also shows 0.1 μF improvement with Hafnium Oxide (HfO2) than Silicon Oxide (SiO2). This paved the way for a better memory application when high-k dielectric is used. The Six Transistor (6T) Static Random Access Memory (SRAM) circuit implemented shows 41.4% improvement in read noise margin for HfO2 than SiO2. It also shows 37.49% improvement in write noise margin and 30.16% improvement in hold noise margin for HfO2 than SiO2.

  6. Agglomerated polymer monoliths with bimetallic nano-particles as flow-through micro-reactors

    International Nuclear Information System (INIS)

    Floris, P.; Twamley, B.; Nesterenko, P.N.; Paull, B.; Connolly, D.

    2012-01-01

    Polymer monoliths in capillary format have been prepared as solid supports for the immobilisation of platinum/palladium bimetallic nano-flowers. Optimum surface coverage of nano-flowers was realised by photografting the monoliths with vinyl azlactone followed by amination with ethylenediamine prior to nano-particle immobilisation. Field emission SEM imaging was used as a characterisation tool for evaluating nano-particle coverage, together with BET surface area analysis to probe the effect of nano-particle immobilisation upon monolith morphology. Ion exchange chromatography was also used to confirm the nature of the covalent attachment of nano-flowers on the monolithic surface. In addition, EDX and ICP analyses were used to quantify platinum and palladium on modified polymer monoliths. Finally the catalytic properties of immobilised bimetallic Pd/Pt nano-flowers were evaluated in flow-through mode, exploiting the porous interconnected flow-paths present in the prepared monoliths (pore diameter ∼ 1-2 μm). Specifically, the reduction of Fe (III) to Fe (II) and the oxidation of NADH to NAD+ were selected as model redox reactions. The use of a porous polymer monolith as an immobilisation substrate (rather than aminated micro-spheres) eliminated the need for a centrifugation step after the reaction. (author)

  7. 7th International Symposium on Gaseous Dielectrics

    CERN Document Server

    James, David

    1994-01-01

    The Seventh International Symposium on Gaseous Dielectrics was held in Knoxville, Tennessee, U. S. A. , on April 24-28, 1994. The symposium continued the interdisciplinary character and comprehensive approach of the preceding six symposia. Gaseous DielecIries VII is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied and industrial areas of gaseous dielectrics. It is hoped that Gaseous DielecIries VII will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Seventh International Symposium on Gaseous Dielectrics consisted of G. Addis (U. S. A. ), L. G. Christophorou (U. S. A. ), F. Y. Chu (Canada), A. H. Cookson (U. S. A. ), O. Farish (U. K. ), I. Gallimberti (Italy) , A. Garscadden (U. S. A. ), D. R. James (U. S. A. ), E. Marode (France), T. Nitta (Japan), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (U. S. A. ), R. J. Van Brunt (U. S. A. ), and W. Zaengl...

  8. SNP typing on the NanoChip electronic microarray

    DEFF Research Database (Denmark)

    Børsting, Claus; Sanchez Sanchez, Juan Jose; Morling, Niels

    2005-01-01

    We describe a single nucleotide polymorphism (SNP) typing protocol developed for the NanoChip electronic microarray. The NanoChip array consists of 100 electrodes covered by a thin hydrogel layer containing streptavidin. An electric currency can be applied to one, several, or all electrodes...

  9. VCP VMware Certified Professional on vSphere 4 Study Guide, Exam VCP-410

    CERN Document Server

    Perry, Brian; Fields, Jeantet

    2010-01-01

    VMware vSphere 4 virtualization certification-here's how to prepare for the exam!. VMware's vSphere 4 is the latest offering from this leading virtualization software provider. With today's emphasis on going green and cutting costs, virtualization of IT infrastructures is a hot topic. What better way to show the marketplace your virtualization expertise than with a VMware Certified Professional on vSphere 4 certification? This in-depth study guide covers all exam objectives, thoroughly preparing you with challenging review questions, real-world scenarios, hands-on exercises, and more.: VMware'

  10. Excited eigenmodes in magnetic vortex states of soft magnetic half-spheres and spherical caps

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Myoung-Woo; Lee, Jae-Hyeok; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr [National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Nanospinics Laboratory, Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2014-12-14

    We studied the magnetization dynamics of excitation modes in special geometrical confinements of soft magnetic half-spheres and spherical caps in magnetic vortex states using finite-element micromagnetic numerical calculations. We found additional fine features of the zeroth- and first-order gyrotropic modes and asymmetric m = +1 and m = −1 azimuthal spin-wave modes, which detailed information is unobtainable from two-dimensional mesh-cell based numerical calculations. Moreover, we examined the perpendicular bias field dependence of the excited eigenmodes, which data provide for an efficient means of control over the excited modes. Such numerical calculations offer additional details or new underlying physics on dynamic features in arbitrary-shape magnetic nano-elements such as half-spheres and spherical caps in magnetic vortex states.

  11. Analysis of tensile strain enhancement in Ge nano-belts on an insulator surrounded by dielectrics

    International Nuclear Information System (INIS)

    Lu Wei-Fang; Li Cheng; Huang Shi-Hao; Lin Guang-Yang; Wang Chen; Yan Guang-Ming; Huang Wei; Lai Hong-Kai; Chen Song-Yan

    2013-01-01

    Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal—oxide—semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si 3 N 4 or SiO 2 for improving their tensile strain and simulate the strain profiles by using the finite difference time domain (FDTD) method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si 3 N 4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. Computer simulations for the nano-scale

    International Nuclear Information System (INIS)

    Stich, I.

    2007-01-01

    A review of methods for computations for the nano-scale is presented. The paper should provide a convenient starting point into computations for the nano-scale as well as a more in depth presentation for those already working in the field of atomic/molecular-scale modeling. The argument is divided in chapters covering the methods for description of the (i) electrons, (ii) ions, and (iii) techniques for efficient solving of the underlying equations. A fairly broad view is taken covering the Hartree-Fock approximation, density functional techniques and quantum Monte-Carlo techniques for electrons. The customary quantum chemistry methods, such as post Hartree-Fock techniques, are only briefly mentioned. Description of both classical and quantum ions is presented. The techniques cover Ehrenfest, Born-Oppenheimer, and Car-Parrinello dynamics. The strong and weak points of both principal and technical nature are analyzed. In the second part we introduce a number of applications to demonstrate the different approximations and techniques introduced in the first part. They cover a wide range of applications such as non-simple liquids, surfaces, molecule-surface interactions, applications in nano technology, etc. These more in depth presentations, while certainly not exhaustive, should provide information on technical aspects of the simulations, typical parameters used, and ways of analysis of the huge amounts of data generated in these large-scale supercomputer simulations. (author)

  13. Morphological, dielectric and electric conductivity characteristics of clay-containing nanohybrids of Poly(N-Vinyl Carbazole) and Polypyrrole

    CSIR Research Space (South Africa)

    Haldar, I

    2012-10-01

    Full Text Available analyses indicated the enhancement of ‘d001’ values in MMT implying intercalation of the polymers into the nano-interlamellar spaces of MMT. The dielectric constants of PNVC-MMT hybrids were improved (60–180) relative to the homopolymer (3...

  14. Making PMMA, PMA, PVAc and PSt nano particles using radiation

    International Nuclear Information System (INIS)

    Hidi, P.; Napper, D.H.; Sangster, D.F.

    2000-01-01

    Full text: During the last decade considerable research effort has been directed to making very small (10-50 nm diam.) nano size polymer particles. Most of the techniques described used more than one surfactant at high concentrations and resulted in relatively low polymer concentration. We have developed methods to make nano size polymer particles from methyl methacrylate (MMA), methyl acrylate (MA), vinyl acetat (Vac) and styrene (St) with a single anionic surfactant and gamma radiation. We succeeded in making nano particles in up to 15% concentration and with much higher polymer/ surfactant ratio than the earlier methods. With the radiation technique we can obtain high yield of polymer and can control the particle size of the polymer in the 2 S 2 0 8 ) instead of gamma irradiation. At present we prefer gamma initiation, because we have much better control and reproducibility of the exothermic polymerisation reaction, hence the critical parameters can be evaluated more accurately. We have started to use the different nano particles prepared for adsorption studies, as seeds for polymerisation and for making transparent gels with nano structure. We are also looking for other applications of the nano particles. It should be noted that the surface area of 1 gram of 20 nm diameter spheres is 300m 2

  15. Dielectric and Insulating Technology 2005 : Reviews & Forecasts

    Science.gov (United States)

    Okamoto, Tatsuki

    This article reports the state-of-art of TC-DEI ( Technical Committee of Dielectrics and Electrical Insulation of IEEJ) activites. The activiteis are basically based on the activites of 8-10 investigation committees under TC-DEI. Recent activites were categorized into three functions in this article and remarkable activity or trend for each category is mentioned as was done in the article of 2003. Thoese are activities on asset management (AI application and insulation diagnosis), activities on new insulating and functional materials (Nano composite) and activities on new insulation technology for power tansmission (high Tc superconducting cable insulation).

  16. Dielectric and Insulating Technology 2006 : Review & Forecast

    Science.gov (United States)

    Okamoto, Tatsuki

    This article reports the state-of-art of TC-DEI ( Technical Committee of Dielectrics and Electrical Insulation of IEEJ) activites. The activiteis are basically based on the activites of 8-10 investigation committees under TC-DEI. Recent activites were categorized into three functions in this article and remarkable activity or trend for each category is mentioned as was seen in the articles of 2005. Those are activities on asset management (AI application and insulation diagnosis), activities on new insulating and functional materials (Nano composite) and activities on new insulation technology for power tansmission (high Tc superconducting cable insulation).

  17. Remote nano-optical beam focusing lens by illusion optics

    Science.gov (United States)

    Margousi, David; Shoorian, Hamed Reza

    2014-08-01

    In this paper, as a new application of illusion optics, a nano-optical plasmonic focusing lens structure is proposed to manipulate the light remotely by employing illusion optics theory. Plasmonic nano-optic lenses that enable super-focusing beyond the diffraction limit have been proposed as an alternative to the conventional dielectric-based refractive lenses. In the presence of an illusion device, the electromagnetic plane-waves can penetrate into a metal layer and a clear focus appears. When the illusion device is removed, waves are blocked to transmit through the metal wall. In comparison with conventional methods, our proposed method avoids any physical changes or damages in the original structure. The proposed structure can be realized by isotropic layered materials, using effective medium theory. The special feature of the proposed structure and the device concepts introduced in this work gives it an opportunity to be used as a flexible element in ultrahigh nano-scale integrated circuits for miniaturization and tuning purposes.

  18. Manipulation of plasmonic resonances in graphene coated dielectric cylinders

    KAUST Repository

    Ge, Lixin

    2016-11-16

    Graphene sheets can support surface plasmon as the Dirac electrons oscillate collectively with electromagnetic waves. Compared with the surface plasmon in conventional metal (e.g., Ag and Au), graphene plasmonic owns many remarkable merits especially in Terahertz and far infrared frequencies, such as deep sub-wavelength, low loss, and high tunability. For graphene coated dielectric nano-scatters, localized surface plasmon (LSP)exist and can be excited under specific conditions. The LSPs are associated with the Mie resonance modes, leading to extraordinary large scattering and absorption cross section. In this work, we study systematically the optical scattering properties for graphene coated dielectric cylinders. It is found that the LSP can be manipulated by geometrical parameters and external electric gating. Generally, the resonance frequencies for different resonance modes are not the same. However, under proper design, we show that different resonance modes (e.g., dipole mode, quadruple mode etc.) can be excited at the same frequency. Thus, the scattering and absorption by graphene coated dielectric cylinders can indeed overcome the single channel limit. Our finding may open up new avenues in applications for the graphene-based THz optoelectronic devices.

  19. Mixed U/Pu oxide fabrication facility for gel-sphere-pac fuel

    International Nuclear Information System (INIS)

    1978-09-01

    This paper describes a conceptual plant which uses the gel-sphere-pac process to fabricate mixed oxide (MOX) fuel and covers (1) fabrication of co-processed MOX fuel and (2) fabrication of co-processed spiked MOX fuel, using 60 Co. The report describes: the fuel fabrication process and plant layout, including scrap and waste processing; and maintenance safety and ventilation measures. A description of the conversion of U and Pu nitrate using a gel sphere process is given in Appendix A

  20. Self-Assembly in the Ferritin Nano-Cage Protein Superfamily

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2011-08-01

    Full Text Available Protein self-assembly, through specific, high affinity, and geometrically constraining protein-protein interactions, can control and lead to complex cellular nano-structures. Establishing an understanding of the underlying principles that govern protein self-assembly is not only essential to appreciate the fundamental biological functions of these structures, but could also provide a basis for their enhancement for nano-material applications. The ferritins are a superfamily of well studied proteins that self-assemble into hollow cage-like structures which are ubiquitously found in both prokaryotes and eukaryotes. Structural studies have revealed that many members of the ferritin family can self-assemble into nano-cages of two types. Maxi-ferritins form hollow spheres with octahedral symmetry composed of twenty-four monomers. Mini-ferritins, on the other hand, are tetrahedrally symmetric, hollow assemblies composed of twelve monomers. This review will focus on the structure of members of the ferritin superfamily, the mechanism of ferritin self-assembly and the structure-function relations of these proteins.

  1. LiNbO3: A photovoltaic substrate for massive parallel manipulation and patterning of nano-objects

    International Nuclear Information System (INIS)

    Carrascosa, M.; García-Cabañes, A.; Jubera, M.; Ramiro, J. B.; Agulló-López, F.

    2015-01-01

    The application of evanescent photovoltaic (PV) fields, generated by visible illumination of Fe:LiNbO 3 substrates, for parallel massive trapping and manipulation of micro- and nano-objects is critically reviewed. The technique has been often referred to as photovoltaic or photorefractive tweezers. The main advantage of the new method is that the involved electrophoretic and/or dielectrophoretic forces do not require any electrodes and large scale manipulation of nano-objects can be easily achieved using the patterning capabilities of light. The paper describes the experimental techniques for particle trapping and the main reported experimental results obtained with a variety of micro- and nano-particles (dielectric and conductive) and different illumination configurations (single beam, holographic geometry, and spatial light modulator projection). The report also pays attention to the physical basis of the method, namely, the coupling of the evanescent photorefractive fields to the dielectric response of the nano-particles. The role of a number of physical parameters such as the contrast and spatial periodicities of the illumination pattern or the particle deposition method is discussed. Moreover, the main properties of the obtained particle patterns in relation to potential applications are summarized, and first demonstrations reviewed. Finally, the PV method is discussed in comparison to other patterning strategies, such as those based on the pyroelectric response and the electric fields associated to domain poling of ferroelectric materials

  2. Dielectric properties of polyhedral oligomeric silsesquioxane (POSS)-based nanocomposites at 77k

    International Nuclear Information System (INIS)

    Pan, Ming-Jen; Gorzkowski, Edward; McAllister, Kelly

    2011-01-01

    The goal of this study is to develop dielectric nanocomposites for high energy density applications at liquid nitrogen temperature by utilizing a unique nano-material polyhedral oligomeric silsesquioxanes (POSS). A POSS molecule is consisted of a silica cage core with 8 silicon and 12 oxygen atoms and organic functional groups attached to the corners of the cage. In this study, we utilize POSS for the fabrication of nanocomposites both as a silica nanoparticle filler to enhance the breakdown strength and as a surfactant for effective dispersion of high permittivity ceramic nanoparticles in a polymer matrix. The matrix materials selected for the study are polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA). The ceramic nanoparticles are barium strontium titanate (BST 50/50) and strontium titanate. The dielectric properties of the solution-cast nanocomposites films were correlated to the composition and processing conditions. We determined that the addition of POSS did not provide enhanced dielectric performance in PVDF- and PMMA-based materials at either room temperature or 77K. In addition, we found that the dielectric breakdown strength of PMMA is lower at 77K than at room temperature, contradicting literature data.

  3. Role of strained nano-regions in the formation of subgrains in CaCu3Ti4O12

    Science.gov (United States)

    Fang, Tsang-Tse; Wang, Yong-Huei; Kuo, Jui-Chao

    2011-07-01

    Single-phase CaCu3Ti4O12 (CCTO) was synthesized by solid-state reaction. Electron backscatter diffraction, scanning electron microscopy, and atomic force microscopy were adopted to characterize the grain orientation, microstructure, and surface morphology of the CCTO samples with or without thermal etching. Bump strained nano-regions induced by the local compositional disorder at a nano-scale have been discovered, being the origin of the formation of subgrains in CCTO. The proposed mechanism for the formation of subgrains involves the formation of etched pits and subboundaries pertaining to the strained nano-regions rather than dislocation displacement. The dielectric response inside the grains of CCTO relevant to the strained nano-regions is also discussed.

  4. Preliminary investigation of polystyrene/MoS{sub 2}-Oleylamine polymer composite for potential application as low-dielectric material in microelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Landi, Giovanni, E-mail: glandi@unisa.it [Institute for Polymers, Composites and Biomaterials (IPCB-CNR), P. Enrico Fermi 1, 80055 Portici (Italy); Department of Industrial Engineering, University of Salerno, Via G. Paolo II 132, 84084 Fisciano (Italy); Altavilla, Claudia; Iannace, Salvatore; Sorrentino, Andrea, E-mail: andrea.sorrentino@cnr.it [Institute for Polymers, Composites and Biomaterials (IPCB-CNR), P. Enrico Fermi 1, 80055 Portici (Italy); Ciambelli, Paolo [Department of Industrial Engineering, University of Salerno, Via G. Paolo II 132, 84084 Fisciano (Italy); Centre NANO-MATES, University of Salerno, Fisciano, Via G. Paolo II 132, 84084 Fisciano (Italy); Neitzert, Heinrich C. [Department of Industrial Engineering, University of Salerno, Via G. Paolo II 132, 84084 Fisciano (Italy)

    2015-12-17

    Insulating materials play a vital role in the design and performance of electrical systems for both steady and transient state conditions. Among the other properties, also in this field, polymer nanocomposites promise to offer exciting improvements. Many studies in the last decade has witnessed significant developments in the area of nano-dielectric materials and significant effects of nano-scale fillers on electric, thermal and mechanical properties of polymeric materials have been observed. However, the developments of new and advanced materials to be used the miniaturization of electronic devices fabrication require extensive studies on electrical insulation characteristics of these materials before they can be used in commercial systems. In this work, Polystyrene (PS) composites were prepared by the blend solution method using MoS{sub 2}@Oleylamine nanosheets as filler. The dielectric properties of the resulting comoposite have been investigated at 300K and in the frequency range between 1000 Hz and 1 MHz. The addition of the MoS{sub 2}@Oleylamine nanosheets leads to a decreasing of the relative dielectric constant and of the electrical conductivity measured in the voltage range between ±500V. Thanks to a possibility to tune the electrical permittivity with the control of MoS{sub 2} concentration, these materials could be used as a low-dielectric material in the microelectronics applications.

  5. Interaction of metallic nanoparticles with dielectric substrates: effect of optical constants

    International Nuclear Information System (INIS)

    Hutter, Tanya; Elliott, Stephen R; Mahajan, Sumeet

    2013-01-01

    In this paper, we study the local-field enhancement in a system of a metallic nanoparticle placed very near to a dielectric substrate. In such systems, intense electric fields are localized in the gap between the particle and the substrate, creating a ‘hot-spot’ under appropriate excitation conditions. We use finite-element numerical simulations in order to study the field enhancement in this dielectric–metal system. More specifically, we show how the optical properties of the dielectric substrate (n and k) affect the plasmonic field enhancement in the nano-gap. We also analyze the degree of field confinement in the gap and discuss it in the context of utilization for surface-enhanced Raman scattering. We finally show the fields generated by real substrates and compare them to metallic ones. (paper)

  6. The many faces of nano in newspaper reporting

    International Nuclear Information System (INIS)

    Boholm, Max; Boholm, Åsa

    2012-01-01

    The morpheme nano in languages such as Swedish and English is a constituent of many words. This article linguistically analyses the meaning potential of nano by focusing on word use in a Swedish newspaper corpus comprising 2,564 articles (1.6 million words) covering a 22-year period (1988–2010). Close to 400 word forms having nano as a constituent have been identified and analyzed. The results suggest that nano covers a broad and heterogeneous conceptual field: (i) as a prefix of the SI system; (ii) in relation to the scientific activities of nanoscience and nanotechnology, including their sub-processes and actors; and (iii) in relation to objects. The identified meanings of nano, besides the standard definition (i.e. ‘billionth part’ in relation to SI units), are ‘operating at the nanometre level’ in relation to activities and their actors and ‘nanometre sized’ and ‘nanotechnological’ in relation to objects; in addition, the less precise and non-technical meaning ‘very small’ is identified. We discuss the implications of the findings for a hypothesis about media influence on public understanding of technology, suggesting that repeated findings in Europe and the USA of little self-reported understanding and knowledge of nanotechnology or nanoscience among the public make sense in light of the polysemy of nano reflected in its broad variety of verbal forms and usages.

  7. The many faces of nano in newspaper reporting

    Science.gov (United States)

    Boholm, Max; Boholm, Åsa

    2012-02-01

    The morpheme nano in languages such as Swedish and English is a constituent of many words. This article linguistically analyses the meaning potential of nano by focusing on word use in a Swedish newspaper corpus comprising 2,564 articles (1.6 million words) covering a 22-year period (1988-2010). Close to 400 word forms having nano as a constituent have been identified and analyzed. The results suggest that nano covers a broad and heterogeneous conceptual field: (i) as a prefix of the SI system; (ii) in relation to the scientific activities of nanoscience and nanotechnology, including their sub-processes and actors; and (iii) in relation to objects. The identified meanings of nano, besides the standard definition (i.e. `billionth part' in relation to SI units), are `operating at the nanometre level' in relation to activities and their actors and `nanometre sized' and `nanotechnological' in relation to objects; in addition, the less precise and non-technical meaning `very small' is identified. We discuss the implications of the findings for a hypothesis about media influence on public understanding of technology, suggesting that repeated findings in Europe and the USA of little self-reported understanding and knowledge of nanotechnology or nanoscience among the public make sense in light of the polysemy of nano reflected in its broad variety of verbal forms and usages.

  8. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  9. Reformulation of the covering and quantizer problems as ground states of interacting particles

    Science.gov (United States)

    Torquato, S.

    2010-11-01

    It is known that the sphere-packing problem and the number-variance problem (closely related to an optimization problem in number theory) can be posed as energy minimizations associated with an infinite number of point particles in d -dimensional Euclidean space Rd interacting via certain repulsive pair potentials. We reformulate the covering and quantizer problems as the determination of the ground states of interacting particles in Rd that generally involve single-body, two-body, three-body, and higher-body interactions. This is done by linking the covering and quantizer problems to certain optimization problems involving the “void” nearest-neighbor functions that arise in the theory of random media and statistical mechanics. These reformulations, which again exemplify the deep interplay between geometry and physics, allow one now to employ theoretical and numerical optimization techniques to analyze and solve these energy minimization problems. The covering and quantizer problems have relevance in numerous applications, including wireless communication network layouts, the search of high-dimensional data parameter spaces, stereotactic radiation therapy, data compression, digital communications, meshing of space for numerical analysis, and coding and cryptography, among other examples. In the first three space dimensions, the best known solutions of the sphere-packing and number-variance problems (or their “dual” solutions) are directly related to those of the covering and quantizer problems, but such relationships may or may not exist for d≥4 , depending on the peculiarities of the dimensions involved. Our reformulation sheds light on the reasons for these similarities and differences. We also show that disordered saturated sphere packings provide relatively thin (economical) coverings and may yield thinner coverings than the best known lattice coverings in sufficiently large dimensions. In the case of the quantizer problem, we derive improved upper

  10. Ion transport study in polymer-nanocomposite films by dielectric spectroscopy and conductivity scaling

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Namrata, E-mail: ntripat@ilstu.edu [Department of Physics, Illinois State University, Normal, IL 61790 (United States); Thakur, Awalendra K. [Department of Physics, Indian Institute of Technology Patna, Bihar 800013 (India); Shukla, Archana [Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology, Bombay 721302 (India); Marx, David T. [Department of Physics, Illinois State University, Normal, IL 61790 (United States)

    2015-07-15

    The dielectric and conductivity response of polymer nanocomposite electrolytes (films of PMMA{sub 4}LiClO{sub 4} dispersed with nano-CeO{sub 2} powder) have been investigated. The dielectric behavior was analyzed via the dielectric permittivity (ε′) and dissipation factor (tan δ) of the samples. The analysis has shown the presence of space charge polarization at lower frequencies. The real part of ac conductivity spectra of materials obeys the Jonscher power law. Parameters such as dc conductivity, hopping rate, activation energies and the concentration of charge carriers were determined from conductivity data using the Almond West formalism. It is observed that the higher ionic conductivity at higher temperature is due to increased thermally-activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from activation energy of migration conduction and from Summerfield scaling. The ac conductivity results are also well correlated with TEM results.

  11. Ion transport study in polymer-nanocomposite films by dielectric spectroscopy and conductivity scaling

    Science.gov (United States)

    Tripathi, Namrata; Thakur, Awalendra K.; Shukla, Archana; Marx, David T.

    2015-07-01

    The dielectric and conductivity response of polymer nanocomposite electrolytes (films of PMMA4LiClO4 dispersed with nano-CeO2 powder) have been investigated. The dielectric behavior was analyzed via the dielectric permittivity (ε‧) and dissipation factor (tan δ) of the samples. The analysis has shown the presence of space charge polarization at lower frequencies. The real part of ac conductivity spectra of materials obeys the Jonscher power law. Parameters such as dc conductivity, hopping rate, activation energies and the concentration of charge carriers were determined from conductivity data using the Almond West formalism. It is observed that the higher ionic conductivity at higher temperature is due to increased thermally-activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from activation energy of migration conduction and from Summerfield scaling. The ac conductivity results are also well correlated with TEM results.

  12. Dielectric barrier discharges applied for soft ionization and their mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Sebastian; Klute, Felix David; Schütz, Alexander; Franzke, Joachim, E-mail: joachim.franzke@isas.de

    2017-01-25

    Dielectric barrier discharges are used for analytical applications as dissociative source for optical emission spectrometry and for ambient-ionization techniques. In the range of ambient-ionization techniques it has attracted much attention in fields like food safety, biological analysis, mass spectrometry for reaction monitoring and imaging forensic identification. In this review some examples are given for the application as desorption/ionization source as well as for the sole application as ionization source with different sample introductions. It will be shown that the detection might depend on the certain distance of the plasma in reference to the sample or the kind of discharge which might be produced by different shapes of the applied high voltage. Some attempts of characterization are presented. A more detailed characterization of the dielectric barrier discharge realized with two ring electrodes, each separately covered with a dielectric layer, is described. - Highlights: • Dielectric barrier discharge applied as desorption/ionization source. • Dielectric barrier discharge applied solely as ionization source. • Different geometries in order to maintain soft ionization. • Characterization of the LTP probe. • Dielectric barrier discharges with two dielectric barriers (ring-ring shape).

  13. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    Directory of Open Access Journals (Sweden)

    Soliman Abdalla

    2016-02-01

    Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown performance is a character of polyimide (PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  14. Enhanced microwave absorption in ZnO/carbonyl iron nano-composites by coating dielectric material

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Chang [School of Physics and Material Science, Anhui University, Hefei 230036 (China); Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China); Fang Qingqing, E-mail: physfangqq@126.com [School of Physics and Material Science, Anhui University, Hefei 230036 (China) and Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China); Yan Fangliang; Wang Weina; Wu Keyue; Liu Yanmei; Lv Qingrong; Zhang Hanming; Zhang Qiping; Li Jinguang; Ding Qiongqiong [School of Physics and Material Science, Anhui University, Hefei 230036 (China); Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China)

    2012-05-15

    The microwave absorption properties of zinc oxide/carbonyl iron composite nanoparticles fabricated by high energy ball milling were studied at 0-20 GHz. Experiments showed that ZnO as a kind of dielectric material coating carbonyl iron particles made the bandwidth of reflection loss (RL)<-5 dB expanding to the low frequency, and enhanced absorption effect obviously. For a 3 mm thickness absorber of ZnO/carbonyl iron after 30 h milling, the values of RL<-5 dB and RL<-8 dB were obtained in the frequency range from 7.0 GHz to 17.8 GHz and from 9.8 dB to 14.9 dB, respectively, and its strongest RL peak was -29.34 dB at 13.59 GHz. The magnetic loss of carbonyl iron particles and the dielectric loss of ZnO particles were the main mechanisms of microwave absorption for the composites. - Highlights: Black-Right-Pointing-Pointer We fabricated zinc oxide/carbonyl iron composites by high energy ball milling. Black-Right-Pointing-Pointer ZnO dielectric property increased absorption effect and absorption bandwidth. Black-Right-Pointing-Pointer Absorbing frequence of composites is expanding to low frequency direction. Black-Right-Pointing-Pointer The craft of high energy ball milling is easy to realize commerce production.

  15. Enhanced microwave absorption in ZnO/carbonyl iron nano-composites by coating dielectric material

    International Nuclear Information System (INIS)

    Zhou Chang; Fang Qingqing; Yan Fangliang; Wang Weina; Wu Keyue; Liu Yanmei; Lv Qingrong; Zhang Hanming; Zhang Qiping; Li Jinguang; Ding Qiongqiong

    2012-01-01

    The microwave absorption properties of zinc oxide/carbonyl iron composite nanoparticles fabricated by high energy ball milling were studied at 0–20 GHz. Experiments showed that ZnO as a kind of dielectric material coating carbonyl iron particles made the bandwidth of reflection loss (RL)<−5 dB expanding to the low frequency, and enhanced absorption effect obviously. For a 3 mm thickness absorber of ZnO/carbonyl iron after 30 h milling, the values of RL<−5 dB and RL<−8 dB were obtained in the frequency range from 7.0 GHz to 17.8 GHz and from 9.8 dB to 14.9 dB, respectively, and its strongest RL peak was −29.34 dB at 13.59 GHz. The magnetic loss of carbonyl iron particles and the dielectric loss of ZnO particles were the main mechanisms of microwave absorption for the composites. - Highlights: ► We fabricated zinc oxide/carbonyl iron composites by high energy ball milling. ► ZnO dielectric property increased absorption effect and absorption bandwidth. ► Absorbing frequence of composites is expanding to low frequency direction. ► The craft of high energy ball milling is easy to realize commerce production.

  16. Single and multiple electromagnetic scattering by dielectric obstacles from a resonance perspective

    International Nuclear Information System (INIS)

    Riley, D.J.

    1987-03-01

    A new application of the singularity expansion method (SEM) is explored. This application combines the classical theory of wave propagation through a multiple-scattering environment and the SEM. Because the SEM is generally considered to be a theory for describing surface currents on conducting scatters, extensions are made which permit, under certain conditions, a singularity expansion representation for the electromagnetic field scattered by a dielectric scatterer. Application of this expansion is then made to the multiple-scattering case using both single and multiple interactions. A resonance scattering tensor form is used for the SEM description which leds to an associated tensor form for the solution to the multiple-scattering problem with each SEM pole effect appearing explicitly. The coherent field is determined for both spatial and SEM parameter random variations. A numerical example for the case of an ensemble of dielectric spheres which possess frequency-dependent loss is also made. Accurate resonance expansions for the single-scattering problem are derived, and resonance trajectories based on the Debye relaxation model for the refractive index are introduced. Application of these resonance expansions is then made to the multiple-scattering results for a slab containing a distribution of spheres with varying radii. Conditions are discussed which describe when the hybrid theory is appropriate. 53 refs., 21 figs., 9 tabs

  17. Drag crisis moderation by thin air layers sustained on superhydrophobic spheres falling in water

    KAUST Repository

    Jetly, Aditya

    2018-01-22

    We investigate the effect of thin air layers naturally sustained on superhydrophobic surfaces on the terminal velocity and drag force of metallic spheres free falling in water. The surface of 20 mm to 60 mm steel or tungsten-carbide spheres is rendered superhydrophobic by a simple coating process that uses commercially available hydrophobic agent. By comparing the free fall of unmodified spheres and superhydrophobic spheres in a 2.5 meters tall water tank, It is demonstrated that even a very thin air layer (~ 1 – 2 μm) that covers the freshly dipped superhydrophobic sphere, can reduce the drag force on the spheres by up to 80 %, at Reynolds numbers 105 - 3×105 , owing to an early drag crisis transition. This study complements prior investigations on the drag reduction efficiency of model gas layers sustained on heated metal spheres falling in liquid by the Leidenfrost effect. The drag reduction effects are expected to have significant implication for the development of sustainable air-layer-based energy saving technologies.

  18. Investigation and Estimation of Structure of Web from Electro spun Nano fibres

    International Nuclear Information System (INIS)

    Malasauskiene, J.; Milasius, R.

    2013-01-01

    During the electro spinning process the web of nano fibres is manufactured by means of electrostatic forces between two electrodes. The diameters of nano fibres usually differ and they depend on various parameters. The different fineness of fibres influences the structure of the web and herewith the end-use properties of such kind of nano material. Analysis of nano fibres diameters distribution also shows big differences; even more, the distributions are not spread along the normal distribution. Understanding the influence of electro spinning parameters and the reason why the shapes of distributions are so sophisticated is very important. The goal of this paper is to analyse the distribution of diameter and to propose the new criterion for nano fibres diameter comparison and web of nano fibres estimation. In this paper the influence of covering time of support material on structure of PA6.6 nano fibre web has been investigated. It was estimated that this parameter does not have a significant influence on the average diameter of nano fibres, and only the structure of web has been influenced by the changes in covering time. According to the results provided the phenomena of nano fibres sticking on the support material at the time of electro spinning can be proved and explained.

  19. Selenite reduction by anaerobic microbial aggregates: Microbial community structure, and proteins associated to the produced selenium spheres.

    Directory of Open Access Journals (Sweden)

    Graciela eGonzalez-Gil

    2016-04-01

    Full Text Available Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se0, insights into the microbial community structure and synthesis of Se0 within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20 % and Pseudomonadaceae (c.a.10 % were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (~200 m of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se0 (nano spheres, with some cells having high numbers of intracellular Se0 spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se0 spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS analysis of extracted Se0 spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se0 spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se0 spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se0 spheres. In view of these and previous findings, a schematic model for the synthesis of Se0 spheres by the microorganisms inhabiting the granular sludge is proposed.

  20. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres

    KAUST Repository

    Gonzalez-Gil, Graciela

    2016-04-26

    Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se0), insights into the microbial community structure and synthesis of Se0 within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se0 (nano)spheres, with some cells having high numbers of intracellular Se0 spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se0 spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se0 spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se0 spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se0 spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se0 spheres. In view of these and previous findings, a schematic model for the synthesis of Se0 spheres by the microorganisms inhabiting the granular sludge is proposed.

  1. Glycine assisted synthesis of flower-like TiO 2 hierarchical spheres and its application in photocatalysis

    KAUST Repository

    Tao, Yugui; Xu, Yanqiu; Pan, Jun; Gu, Hao; Qin, Changyun; Zhou, Peng

    2012-01-01

    Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2O 2). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2. © 2012 Elsevier B.V.

  2. Glycine assisted synthesis of flower-like TiO 2 hierarchical spheres and its application in photocatalysis

    KAUST Repository

    Tao, Yugui

    2012-11-01

    Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2O 2). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2. © 2012 Elsevier B.V.

  3. Design and Fabrication of Carbon Nano tube for Medical Application

    International Nuclear Information System (INIS)

    Azniza Abas; Nuzaihan, M.N.; Hafiza, N.; Nazwa, T.

    2011-01-01

    Carbon nano tubes or known as CNTs are allotropes of carbon with a cylindrical nano structure. They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors [1]. Due to its ordinary properties this research will based on BIOSENSOR device. Normally these CNTs biosensor are based on an enzyme catalyzed reaction that will produce either electrons or protons. In particular, it is useful in genetic profiling of human diseases, which includes in identifying genes that are expressed in certain diseases such as cancer [2]. This research will based on design and fabricate sensor or device using carbon nano tube and integrate carbon nano tube (CNTs) onto wafer using combination of dichlorophosphate and nano manipulation. Carbon nano tubes device mask are design using AUTOCAD software; there is four mask involved, first mask is Gate Formation,second mask is insulation layer third mask is source and drain and final mask forth mask is used as test channel. For fabrication and optimization of biosensor using carbon nano tube CNT that will be involve both microfabrication and nano fabrication. This process will involve conventional photolithography process, electron beam evaporator, thermal oxidation and wet etching process. To inspect and characterize carbon nano tube electrical properties it will involve tools such as SEM, AFM, Dielectric Analyzer, IV-CV and Semiconductor Parametric Analyzer system. This inspection is very important to produce a perfect profile to produce a good biosensor based on carbon nano tube structure. Preparation of various samples for testing functionality of the device this various samples and conditions will be done to ensure the detection is precise. Conductivity and capacitance effect will be tested electrically to detect the hybridization of the sample. (author)

  4. Definition by modelling, optimization and characterization of a neutron spectrometry system based on Bonner spheres extended to the high-energy range

    International Nuclear Information System (INIS)

    Serre, S.

    2010-01-01

    This research thesis first describes the problematic of the effects of natural radiation on micro- and nano-electronic components, and the atmospheric-radiative stress of atmospheric neutrons from cosmic origin: issue of 'Single event upsets', present knowledge of the atmospheric radiative environment induced by cosmic rays. The author then presents the neutron-based detection and spectrometry by using the Bonner sphere technique: principle of moderating spheres, definition and mathematical formulation of neutron spectrometry using Bonner spheres, active sensors of thermal neutrons, response of a system to conventional Bonner spheres, extension to the range of high energies. Then, he reports the development of a Bonner sphere system extended to the high-energy range for the spectrometry of atmospheric neutrons: definition of a conventional system, Monte Carlo calculation of response functions, development of the response matrix, representation and semi-empirical verification of fluence response, uncertainty analysis, extension to high energies, and measurement tests of the spectrometer. He reports the use of a Monte Carlo simulation to characterize the spectrometer response in the high-energy range

  5. Conservation of leather historical object by nano technology in ...

    African Journals Online (AJOL)

    This paper examines the conservation of Antibacterial by Nano materials in the manufacture of leather and the implication of such a processes deteriorated of aging leather. As a sample study to improve this process historical cover book is used. Experimental methods are SEM EDX, Cultural Bacterial, Nano materials such ...

  6. Electromagnetic power flow between opposite sides of a lossy dielectric sphere using spherical vector wave expansion

    DEFF Research Database (Denmark)

    Nour, Baqer; Breinbjerg, Olav

    2010-01-01

    This article addresses the problem of communication in near field region. The proposed example is the communication between two small antennas, which are modelled as an electric dipole antenna (transmitter) and a small box (receiver), near a sphere that models a head. Spherical vector wave...

  7. Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

    Science.gov (United States)

    Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

    2007-08-01

    Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

  8. Effect of organo-clay on the dielectric relaxation response of silicone rubber

    International Nuclear Information System (INIS)

    Gharavi, N; Razzaghi-Kashani, M; Golshan-Ebrahimi, N

    2010-01-01

    Dielectric elastomers are light weight, low-cost, highly deformable and fast response smart materials capable of converting electrical energy into mechanical work or vice versa. Silicone rubber is a well-known dielectric elastomer which is used as actuator, and in order to enhance the efficiency of this smart material, compounding of silicone rubber with various fillers can be carried out. The effect of organically modified montmorillonite (OMMT) nano-clay on improvement of dielectric properties, actuation stress and its relaxation response was considered in this study. OMMT was dispersed in room temperature vulcanized (RTV) silicone rubber, and a composite film was cast. Using an in-house actuation set-up, it was shown that the actuation stress for a given electric field intensity is higher for composites than that for pristine silicone rubber. Also, the time-dependent actuation response of the samples was evaluated, and it was shown that the characteristic relaxation time of the actuation stress for composites is less than for the pristine rubber as a result of OMMT addition

  9. Gate dielectric strength dependent performance of CNT MOSFET and CNT TFET: A tight binding study

    Directory of Open Access Journals (Sweden)

    Md. Shamim Sarker

    Full Text Available This paper presents a comparative study between CNT MOSFET and CNT TFET taking into account of different dielectric strength of gate oxide materials. Here we have studied the transfer characteristics, on/off current (ION/IOFF ratio and subthreshold slope of the device using Non Equilibrium Greens Function (NEGF formalism in tight binding frameworks. The results are obtained by solving the NEGF and Poisson’s equation self-consistently in NanoTCADViDES environment and found that the ON state performance of CNT MOSFET and CNT TFET have significant dependency on the dielectric strength of the gate oxide materials. The figure of merits of the devices also demonstrates that the CNT TFET is promising for high-speed and low-power logic applications. Keywords: CNT TFET, Subthreshold slop, Barrier width, Conduction band (C.B and Valance band (V.B, Oxide dielectric strength, Tight binding approach

  10. Glycine assisted synthesis of flower-like TiO2 hierarchical spheres and its application in photocatalysis

    International Nuclear Information System (INIS)

    Tao, Yu-gui; Xu, Yan-qiu; Pan, Jun; Gu, Hao; Qin, Chang-yun; Zhou, Peng

    2012-01-01

    Graphical abstract: Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. The obtained TiO 2 sample showed good photocatalytic activity of decomposition of methyl orange under sunlight. Highlights: ► Flower-like TiO 2 hierarchical spheres were synthesized by glycine assistant. ► Reaction time, temperature, solution pH and glycine dosage were studied. ► The formation of the flower-like TiO 2 spheres is an Ostwald ripening process. ► Flower-like TiO 2 showed high photocatalytic activity under sunlight. - Abstract: Flower-like anatase TiO 2 hierarchical spheres assembled by nanosheets were synthesized by glycine assistant via a simple hydrothermal approach and after-annealing process. These flower-like spheres are about 2 μm in diameter with sheet thickness about 20 nm. Results showed reaction time, temperature, solution pH and glycine dosage all played an important role in control of shape and size of the as-synthesized TiO 2 nanocrystals. The photocatalytic activity of this nano-TiO 2 was evaluated by the photocatalytic oxidation decomposition of methyl orange under sunlight illumination in the presence of hydrogen peroxide (H 2 O 2 ). The photocatalytic activity of the obtained TiO 2 was higher than that of commercial TiO 2 .

  11. Automated general temperature correction method for dielectric soil moisture sensors

    Science.gov (United States)

    Kapilaratne, R. G. C. Jeewantinie; Lu, Minjiao

    2017-08-01

    An effective temperature correction method for dielectric sensors is important to ensure the accuracy of soil water content (SWC) measurements of local to regional-scale soil moisture monitoring networks. These networks are extensively using highly temperature sensitive dielectric sensors due to their low cost, ease of use and less power consumption. Yet there is no general temperature correction method for dielectric sensors, instead sensor or site dependent correction algorithms are employed. Such methods become ineffective at soil moisture monitoring networks with different sensor setups and those that cover diverse climatic conditions and soil types. This study attempted to develop a general temperature correction method for dielectric sensors which can be commonly used regardless of the differences in sensor type, climatic conditions and soil type without rainfall data. In this work an automated general temperature correction method was developed by adopting previously developed temperature correction algorithms using time domain reflectometry (TDR) measurements to ThetaProbe ML2X, Stevens Hydra probe II and Decagon Devices EC-TM sensor measurements. The rainy day effects removal procedure from SWC data was automated by incorporating a statistical inference technique with temperature correction algorithms. The temperature correction method was evaluated using 34 stations from the International Soil Moisture Monitoring Network and another nine stations from a local soil moisture monitoring network in Mongolia. Soil moisture monitoring networks used in this study cover four major climates and six major soil types. Results indicated that the automated temperature correction algorithms developed in this study can eliminate temperature effects from dielectric sensor measurements successfully even without on-site rainfall data. Furthermore, it has been found that actual daily average of SWC has been changed due to temperature effects of dielectric sensors with a

  12. Spherical active coated nano-particles – impact of the electric Hertzian dipole orientation

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Mostafavi, M.; Malureanu, Radu

    2011-01-01

    Spherical active coated nano-particles comprised of a silica nano-cylinder core covered with a plasmonic nano-shell are investigated with regard to their near- and far-field properties. The source of excitation is taken to be that of a tangential or a radial electric Hertizan dipole while three...

  13. Dielectric relaxation in biological systems physical principles, methods, and applications

    CERN Document Server

    Feldman, Yuri

    2015-01-01

    This title covers the theoretical basis and practical aspects of the study of dielectric properties of biological systems, such as water, electrolyte and polyelectrolytes, solutions of biological macromolecules, cells suspensions and cellular systems.

  14. Film boiling from spheres in single- and two-phase flow

    International Nuclear Information System (INIS)

    Liu, C.; Theofanous, T.G.; Yuen, W.W.

    1992-01-01

    Experimental data on film boiling heat transfer from single, inductively heated, spheres in single- and two-phase flow (saturated water and steam, respectively) are presented. In the single-phase-flow experiments water velocities ranged from 0.1 to 2.0 m/s; in the two-phase-flow experiments superficial water and steam velocities covered 0.1 to 0.6 m/s and 4 to 10 m/s, respectively. All experiments were run at atmospheric pressure and with sphere temperatures from 900C down to quenching. Limited interpretations of the single-phase- flow data are possible, but the two-phase-flow data are new and unique

  15. Modelling effective dielectric properties of materials containing diverse types of biological cells

    International Nuclear Information System (INIS)

    Huclova, Sonja; Froehlich, Juerg; Erni, Daniel

    2010-01-01

    An efficient and versatile numerical method for the generation of different realistically shaped biological cells is developed. This framework is used to calculate the dielectric spectra of materials containing specific types of biological cells. For the generation of the numerical models of the cells a flexible parametrization method based on the so-called superformula is applied including the option of obtaining non-axisymmetric shapes such as box-shaped cells and even shapes corresponding to echinocytes. The dielectric spectra of effective media containing various cell morphologies are calculated focusing on the dependence of the spectral features on the cell shape. The numerical method is validated by comparing a model of spherical inclusions at a low volume fraction with the analytical solution obtained by the Maxwell-Garnett mixing formula, resulting in good agreement. Our simulation data for different cell shapes suggest that around 1MHz the effective dielectric properties of different cell shapes at different volume fractions significantly deviate from the spherical case. The most pronounced change exhibits ε eff between 0.1 and 1 MHz with a deviation of up to 35% for a box-shaped cell and 15% for an echinocyte compared with the sphere at a volume fraction of 0.4. This hampers the unique interpretation of changes in cellular features measured by dielectric spectroscopy when simplified material models are used.

  16. Falling-sphere radioactive viscometry

    International Nuclear Information System (INIS)

    Souza, R. de.

    1987-01-01

    In this work the falling sphere viscometric method was studies experimentally using a sphere tagged with 198 Au radiosotopo, the objective being the demosntration of the advantages of this technique in relation to the traditional method. The utilisation of the falling radioactive sphere permits the point-point monitoring of sphere position as a function of count rate. The fall tube wall and end effects were determined by this technique. Tests were performed with spheres of different diameters in four tubes. The application of this technique demosntrated the wall and end effects in sphere speed. The case of sphere fall in the steady slow regime allowed the determination of the terminal velocity, showing the increase of botton end effect as the sphere approaches the tube base. In the case the transient slow regime, the sphere was initially in a state of respose near the top surface. The data obtained show the influence of the free surface and wall on the sphere acceleration. These experimental data were applied to the Basset equation on order to verify the behaviour of the terms in this equation. (author) [pt

  17. High-pressure cell for simultaneous dielectric and neutron spectroscopy

    DEFF Research Database (Denmark)

    Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo

    2018-01-01

    In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation......, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data...

  18. Dielectric and Radiative Properties of Sea Foam at Microwave Frequencies: Conceptual Understanding of Foam Emissivity

    OpenAIRE

    Peter W. Gaiser; Magdalena D. Anguelova

    2012-01-01

    Foam fraction can be retrieved from space-based microwave radiometric data at frequencies from 1 to 37 GHz. The retrievals require modeling of ocean surface emissivity fully covered with sea foam. To model foam emissivity well, knowledge of foam properties, both mechanical and dielectric, is necessary because these control the radiative processes in foam. We present a physical description of foam dielectric properties obtained from the foam dielectric constant including foam skin depth; foam ...

  19. VMware vSphere PowerCLI Reference Automating vSphere Administration

    CERN Document Server

    Dekens, Luc; Sizemore, Glenn; van Lieshout, Arnim; Medd, Jonathan

    2011-01-01

    Your One-Stop Reference for VMware vSphere Automation If you manage vSphere in a Windows environment, automating routine tasks can save you time and increase efficiency. VMware vSphere PowerCLI is a set of pre-built commands based on Windows PowerShell that is designed to help you automate vSphere processes involving virtual machines, datacenters, storage, networks, and more. This detailed guide-using a practical, task-based approach and real-world examples-shows you how to get the most out of PowerCLI's handy cmdlets. Learn how to: Automate vCenter Server and ESX/ESX(i) Server deployment and

  20. Possible Lead Free Nanocomposite Dielectrics for High Energy Storage Applications

    Directory of Open Access Journals (Sweden)

    Srinivas Kurpati

    2017-03-01

    Full Text Available There is an increasing demand to improve the energy density of dielectric capacitors for satisfying the next generation material systems. One effective approach is to embed high dielectric constant inclusions such as lead zirconia titanate in polymer matrix. However, with the increasing concerns on environmental safety and biocompatibility, the need to expel lead (Pb from modern electronics has been receiving more attention. Using high aspect ratio dielectric inclusions such as nanowires could lead to further enhancement of energy density. Therefore, the present brief review work focuses on the feasibility of development of a lead-free nanowire reinforced polymer matrix capacitor for energy storage application. It is expected that Lead-free sodium Niobate nanowires (NaNbO3 and Boron nitride will be a future candidate to be synthesized using simple hydrothermal method, followed by mixing them with polyvinylidene fluoride (PVDF/ divinyl tetramethyl disiloxanebis (benzocyclobutene matrix using a solution-casting method for Nanocomposites fabrication. The energy density of NaNbO3 and BN based composites are also be compared with that of lead-containing (PbTiO3/PVDF Nano composites to show the feasibility of replacing lead-containing materials from high-energy density dielectric capacitors. Further, this paper explores the feasibility of these materials for space applications because of high energy storage capacity, more flexibility and high operating temperatures. This paper is very much useful researchers who would like to work on polymer nanocomposites for high energy storage applications.

  1. Top-gate dielectric induced doping and scattering of charge carriers in epitaxial graphene

    Science.gov (United States)

    Puls, Conor P.; Staley, Neal E.; Moon, Jeong-Sun; Robinson, Joshua A.; Campbell, Paul M.; Tedesco, Joseph L.; Myers-Ward, Rachael L.; Eddy, Charles R.; Gaskill, D. Kurt; Liu, Ying

    2011-07-01

    We show that an e-gun deposited dielectric impose severe limits on epitaxial graphene-based device performance based on Raman spectroscopy and low-temperature transport measurements. Specifically, we show from studies of epitaxial graphene Hall bars covered by SiO2 that the measured carrier density is strongly inhomogenous and predominantly induced by charged impurities at the grapheme/dielectric interface that limit mobility via Coulomb interactions. Our work emphasizes that material integration of epitaxial graphene and a gate dielectric is the next major road block towards the realization of graphene-based electronics.

  2. Vertical dielectric screening of few-layer van der Waals semiconductors.

    Science.gov (United States)

    Koo, Jahyun; Gao, Shiyuan; Lee, Hoonkyung; Yang, Li

    2017-10-05

    Vertical dielectric screening is a fundamental parameter of few-layer van der Waals two-dimensional (2D) semiconductors. However, unlike the widely-accepted wisdom claiming that the vertical dielectric screening is sensitive to the thickness, our first-principles calculation based on the linear response theory (within the weak field limit) reveals that this screening is independent of the thickness and, in fact, it is the same as the corresponding bulk value. This conclusion is verified in a wide range of 2D paraelectric semiconductors, covering narrow-gap ones and wide-gap ones with different crystal symmetries, providing an efficient and reliable way to calculate and predict static dielectric screening of reduced-dimensional materials. Employing this conclusion, we satisfactorily explain the tunable band gap in gated 2D semiconductors. We further propose to engineer the vertical dielectric screening by changing the interlayer distance via vertical pressure or hybrid structures. Our predicted vertical dielectric screening can substantially simplify the understanding of a wide range of measurements and it is crucial for designing 2D functional devices.

  3. EM wave propagation analysis in plasma covered radar absorbing material

    CERN Document Server

    Singh, Hema; Rawat, Harish Singh

    2017-01-01

    This book focuses on EM propagation characteristics within multilayered plasma-dielectric-metallic media. The method used for analysis is impedance transformation method. Plasma covered radar absorbing material is approximated as a multi-layered dielectric medium. The plasma is considered to be bounded homogeneous/inhomogeneous medium. The reflection coefficient and hence return loss is analytically derived. The role of plasma parameters, such as electron density, collision frequency, plasma thickness, and plasma density profile in the absorption behavior of multi-layered plasma-RAM structure is described. This book provides a clearer picture of EM propagation within plasma. The reader will get an insight of plasma parameters that play significant role in deciding the absorption characteristics of plasma covered surfaces.

  4. Ultralow frequency bridge for dielectric measurements: applications to electrects

    International Nuclear Information System (INIS)

    Slaets, J.

    1976-01-01

    The problem of U.L.F. (Ultra Low Frequency) dielectric relaxation is investigated. An experimental model is proposed for a bridge covering the range of 10 -3 Hz-10Hz, pased on phase shift measurements originally proposed by Van Turhout and collaborators. The main experimental problems are also analyzed with such U.L.F. measurements and describe its construction and performance. The theoretical correlation between U.L.F. dielectric relaxation and electret thermal stimulated currents is also investigated. A correction for the integral expression given by Turnhout and collaborators, is calculated in particular that takes into account the value of the activation energy in the relation between the two techniques.The correction is important for values of the activation energy below 0,5eV, which occur frequently in dielectric relaxation processes. (Author) [pt

  5. Microscopic evolution of dielectric nanoparticles at different calcination temperatures synthesized via sol-gel auto-combustion

    International Nuclear Information System (INIS)

    Adil, Muhammad; Zaid, Hasnah Mohd; Chuan, Lee Kean; Latiff, Noor Rasyada Ahmad; Alta’ee, Ali F.

    2015-01-01

    Dielectric nano powder synthesis is carried by a simple and fast sol-gel auto-combustion method. The transformation of crystalline phases of as-synthesized nano powders is investigated through the detailed transmission electron microscopy (TEM), revealed the crystallographic alterations and morphological information even at lattice scale. From specific area electron diffraction (SAED) pattern, has specified the d-spacing and corresponding planes supported by the observed lattice fringes. The morphological characterization of nanoparticles is performed through field-emission scanning electron microscopy (FESEM), exhibiting the increment in particle size due to agglomeration with the increase in annealing temperature. Furthermore, EDX pattern has been used to verify the formation of nanoparticles by revealing the presence of required elements

  6. Microscopic evolution of dielectric nanoparticles at different calcination temperatures synthesized via sol-gel auto-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Adil, Muhammad, E-mail: muhammadadil86@hotmail.com; Zaid, Hasnah Mohd, E-mail: hasnamz@petronas.com.my; Chuan, Lee Kean, E-mail: lee.kc@petronas.com.my; Latiff, Noor Rasyada Ahmad, E-mail: syasya.latiff@gmail.com [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Alta’ee, Ali F., E-mail: ali-mangi@petronas.com.my [Geoscience and Petroleum Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    Dielectric nano powder synthesis is carried by a simple and fast sol-gel auto-combustion method. The transformation of crystalline phases of as-synthesized nano powders is investigated through the detailed transmission electron microscopy (TEM), revealed the crystallographic alterations and morphological information even at lattice scale. From specific area electron diffraction (SAED) pattern, has specified the d-spacing and corresponding planes supported by the observed lattice fringes. The morphological characterization of nanoparticles is performed through field-emission scanning electron microscopy (FESEM), exhibiting the increment in particle size due to agglomeration with the increase in annealing temperature. Furthermore, EDX pattern has been used to verify the formation of nanoparticles by revealing the presence of required elements.

  7. The effect of organo-clay on the dielectric properties of silicone rubber

    International Nuclear Information System (INIS)

    Razzaghi-Kashani, M; Gharavi, N; Javadi, S

    2008-01-01

    Dielectric elastomers are highly deformable and fast response smart materials capable of actuation under electric fields. Among commercially available dielectric elastomers, silicone rubber can be compounded with different fillers in order to modify its electrical and mechanical properties. To study the effect of organically modified montmorillonite (OMMT) on the dielectric properties of silicone rubber, OMMT was added to this rubber at two levels, 2% and 5%, using two methods, low-shear and high-shear mixing. Composites were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD patterns showed different crystallite structures for silicate platelets in the rubber matrix as a result of the two different mixing methods. In low-shear mixing, the ordered crystallite structure of the clay remains almost unchanged, whereas in high-shear mixing it loses its ordered structure, leading to the disappearance of the diffraction peaks. SEM and AFM micrographs depicted better dispersion and more uniform distribution of the organo-clay under high-shear mixing compared to those obtained by low-shear mixing. The tensile properties also confirmed the different degree of dispersion of the nano-clay resulting from the two different methods of mixing. The dielectric properties of the composites were measured under AC electric fields, and the results were compared with reference silicone rubbers with no OMMT. It was shown that the order of organo-clay layers in the less dispersed structure of the clay imparts an additional ionic polarization and higher dielectric permittivity compared to the case where the clay layers are more dispersed and lost their order. The storage and loss dielectric constants of base silicone rubber increase when it is compounded with OMMT

  8. Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging

    Science.gov (United States)

    Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.

    2011-01-01

    Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter

  9. Enhanced light absorption of silicon solar cells with dielectric nanostructured back reflector

    Science.gov (United States)

    Ren, Rui; Zhong, Zheng

    2018-06-01

    This paper investigates the light absorption property of nanostructured dielectric reflectors in silicon thin film solar cells using numerical simulation. Flat thin film solar cell with ZnO nanostructured back reflector can produce comparable photocurrent to the control model with Ag nanostructured back reflector. Furthermore, when it is integrated with nano-pillar surface decoration, a photocurrent density of 29.5 mA/cm2 can be achieved, demonstrating a photocurrent enhancement of 5% as compared to the model with Ag nanostructured back reflector.

  10. Iron oxide nanoparticle layer templated by polydopamine spheres: a novel scaffold toward hollow-mesoporous magnetic nanoreactors.

    Science.gov (United States)

    Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F; Su, Wu

    2015-01-14

    Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m(2) g(-1)). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality.

  11. Super dielectric capacitor using scaffold dielectric

    OpenAIRE

    Phillips, Jonathan

    2018-01-01

    Patent A capacitor having first and second electrodes and a scaffold dielectric. The scaffold dielectric comprises an insulating material with a plurality of longitudinal channels extending across the dielectric and filled with a liquid comprising cations and anions. The plurality of longitudinal channels are substantially parallel and the liquid within the longitudinal channels generally has an ionic strength of at least 0.1. Capacitance results from the migrations of...

  12. Method of making dielectric capacitors with increased dielectric breakdown strength

    Science.gov (United States)

    Ma, Beihai; Balachandran, Uthamalingam; Liu, Shanshan

    2017-05-09

    The invention is directed to a process for making a dielectric ceramic film capacitor and the ceramic dielectric laminated capacitor formed therefrom, the dielectric ceramic film capacitors having increased dielectric breakdown strength. The invention increases breakdown strength by embedding a conductive oxide layer between electrode layers within the dielectric layer of the capacitors. The conductive oxide layer redistributes and dissipates charge, thus mitigating charge concentration and micro fractures formed within the dielectric by electric fields.

  13. Nuclear reactor using fuel sphere for combustion and fuel spheres for breeding

    International Nuclear Information System (INIS)

    Yamashita, Kiyonobu.

    1995-01-01

    The present invention concerns a pebble bed-type reactor which can efficiently convert parent nuclides to fission nuclides. Fuel spheres for combustion having fission nuclides as main fuels, and fuel spheres for breeding having parent nuclides as main fuels are used separately, in the pebble bed-type reactor. According to the present invention, fuel spheres for breeding can be stayed in a reactor core for a long period of time, so that parent nuclides can be sufficiently converted into fission nuclides. In addition, since fuel spheres for breeding are loaded repeatedly, the amount thereof to be used is reduced. Therefore, the amount of the fuel spheres for breeding is small even when they are re-processed. On the other hand, since the content of the fission nuclides in the fuel spheres for breeding is not great, they can be put to final storage. This is attributable that although the fuel spheres for breeding contain fission nuclides generated by conversion, the fission nuclides are annihilated by nuclear fission reactions at the same time with the generation thereof. (I.S.)

  14. Heat transfer under transition and film boiling of liquids at dimpled spheres and cylinders

    Science.gov (United States)

    Zhukov, V. M.; Kuzma-Kichta, Yu. A.; Lavrikov, A. V.; Belov, K. I.; Len’kov, V. A.

    2018-03-01

    The article presents the results of studies of heat transfer and film and transition boiling mechanism of nitrogen, Refrigerant R-113, and water at spheres and vertical cylinders, which surfaces are covered with spherical dimples.. The data were obtained under the conditions of pool boiling and natural circulation in vertical 1.0 and 2.5 mm wide annular channels. Hemispherical dimples of 3 mm diameter (h/d = 0.17) were made on sample surfaces. The dimples occupied 45% of the sphere surface and 37% of the cylinder surface. In some tests, the dimpled surface was additionally covered with low-conductive coating (10 µm film). Minimal cooling time for the sphere with dimples and low-conductive coating took place under natural circulation in 2.5 mm annular gap and it was almost 2.5 times lower than that for a smooth sphere under pool boiling. It is shown that at pool boiling the presence of dimples and low-conductive coating leads to heat transfer enhancement at transition and film boiling regimes, while at natural circulation such an enhancement occurs at film boiling with high temperature differences. The tests at natural circulation in vertical annular channels of different width showed that in this case an intensity of boiling heat transfer is higher than that at pool boiling. High-speed filming of film boiling process on the surfaces with dimples was conducted.

  15. Drug Delivery Systems: A New Frontier in Nano-technology

    Directory of Open Access Journals (Sweden)

    Chamindri Witharana

    2017-09-01

    Full Text Available Nano-technology is a recent advancement in science, defined as “Science, engineering, and technology conducted at the Nano scale” (National nanotechnology initiatives in USA. Applications of Nano-technology cover a vast range from basic material science, personal care applications, agriculture, and medicine. Nano-technology is used in field of medicine for treatment, diagnostic, monitoring, genetic engineering, and drug delivery. There are two main types of Nano Particles (NPs used in drug delivery; organic NPs and inorganic NPs. In drug delivery, the drug-Nano- Particle (NP conjugate should be able to deliver drugs to the target site without degradation in gastrointestinal track and without reducing drug activity. Further, it should attack to target cells without causing any adverse effects. The ultimate goal of NP drug delivery is to improve proper treatment, effectiveness, less side effects with safety and patient adherence as well as reduction in the cost.

  16. Graphs with Eulerian unit spheres

    OpenAIRE

    Knill, Oliver

    2015-01-01

    d-spheres in graph theory are inductively defined as graphs for which all unit spheres S(x) are (d-1)-spheres and that the removal of one vertex renders the graph contractible. Eulerian d-spheres are geometric d-spheres which are d+1 colorable. We prove here that G is an Eulerian sphere if and only if the degrees of all the (d-2)-dimensional sub-simplices in G are even. This generalizes a Kempe-Heawood result for d=2 and is work related to the conjecture that all d-spheres have chromatic numb...

  17. Electro-optic and dielectric properties of new binary ferroelectric and antiferroelectric liquid crystalline mixtures

    Czech Academy of Sciences Publication Activity Database

    Fitas, J.; Marzec, M.; Kurp, K.; Żurowska, M.; Tykarska, M.; Bubnov, Alexej

    2017-01-01

    Roč. 44, č. 9 (2017), s. 1468-1476 ISSN 0267-8292 R&D Projects: GA MŠk(CZ) LD14007; GA ČR GA15-02843S Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : liquid crystals * ferroelectric and antiferroelectric phase * binary mixture * dielectric spectroscopy * switching time * tilt angle Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 2.661, year: 2016

  18. A Thermodynamically-Consistent Non-Ideal Stochastic Hard-Sphere Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Donev, A; Alder, B J; Garcia, A L

    2009-08-03

    A grid-free variant of the Direct Simulation Monte Carlo (DSMC) method is proposed, named the Isotropic DSMC (I-DSMC) method, that is suitable for simulating collision-dominated dense fluid flows. The I-DSMC algorithm eliminates all grid artifacts from the traditional DSMC algorithm and is Galilean invariant and microscopically isotropic. The stochastic collision rules in I-DSMC are modified to introduce a non-ideal structure factor that gives consistent compressibility, as first proposed in [Phys. Rev. Lett. 101:075902 (2008)]. The resulting Stochastic Hard Sphere Dynamics (SHSD) fluid is empirically shown to be thermodynamically identical to a deterministic Hamiltonian system of penetrable spheres interacting with a linear core pair potential, well-described by the hypernetted chain (HNC) approximation. We develop a kinetic theory for the SHSD fluid to obtain estimates for the transport coefficients that are in excellent agreement with particle simulations over a wide range of densities and collision rates. The fluctuating hydrodynamic behavior of the SHSD fluid is verified by comparing its dynamic structure factor against theory based on the Landau-Lifshitz Navier-Stokes equations. We also study the Brownian motion of a nano-particle suspended in an SHSD fluid and find a long-time power-law tail in its velocity autocorrelation function consistent with hydrodynamic theory and molecular dynamics calculations.

  19. Scattering Study of Conductive-Dielectric Nano/Micro-Grained Single Crystals Based on Poly(ethylene glycol, Poly(3-hexyl thiophene and Polyaniline

    Directory of Open Access Journals (Sweden)

    Samira Agbolaghi

    2017-12-01

    Full Text Available Two types of rod-coil block copolymers including poly(3-hexylthiophene-block-poly(ethylene glycol (P3HT-b-PEG and PEG-block-polyaniline (PANI were synthesized using Grignard metathesis polymerization, Suzuki coupling, and interfacial polymerization. Afterward, two types of single crystals were grown by self-seeding methodology to investigate the coily and rod blocks in grafted brushes and ordered crystalline configurations. The conductive P3HT fibrillar single crystals covered by the dielectric coily PEG oligomers were grown from toluene, xylene, and anisole, and characterized by atomic force microscopy (AFM and grazing wide angle X-ray scattering (GIWAXS. Longer P3HT backbones resulted in folding, whereas shorter ones had a high tendency towards backbone lamination. The effective factors on folding of long P3HT backbones in the single crystal structures were the solvent quality and crystallization temperature. Better solvents due to decelerating the growth condition led to a higher number of foldings. Via increasing the crystallization temperature, the system decreased the folding number to maintain its stability. Poorer solvents also reflected a higher stacking in hexyl side chain and π-π stacking directions. The dielectric lamellar PEG single crystals sandwiched between the PANI nanorods were grown from amyl acetate, and analyzed using the interface distribution function (IDF of SAXS and AFM. The molecular weights of PANI and PEG blocks and crystallization temperature were focused while studying the grown single crystals.

  20. Monte Carlo calculations of the free-molecule drag on chains of uniform spheres

    International Nuclear Information System (INIS)

    Dahneke, B.; Chan, P.

    1980-01-01

    Monte Carlo calculations of the free-molecule drag on straight chains of uniform spheres are presented. The drag on a long chain is expressed in terms of the drag on a basic chain unit (two hemispheres touching at their poles) multiplied by the number of spheres in the chain. Since there is no interaction between the basic chain units, it is argued that the results also apply as a good approximation to the drag on kinked and branched chains covering a broad range of geometries. Experimental data are cited which support this claim

  1. Low-dielectric layer increases nanosecond electric discharges in distilled water

    KAUST Repository

    Hamdan, Ahmad; Cha, Min

    2016-01-01

    decreasing of the energy consumption are the main goals of today’s research. Here we present an experimental study of nanosecond discharge in distilled water covered by a layer of dielectric material. We demonstrate through this paper that the discharge

  2. VMware vSphere Design

    CERN Document Server

    Guthrie, Forbes; Saidel-Keesing, Maish

    2011-01-01

    The only book focused on designing VMware vSphere implementations.VMware vSphere is the most widely deployed virtualization platform today. Considered the most robust and sophisticated hypervisor product, vSphere is the de facto standard for businesses, both large and small. This book is the only one of its kind to concisely explain how to execute a successful vSphere architecture, tailored to meet your company's needs. Expert authors share with you the factors that shape the design of a vSphere implementation. Learn how to make the right design decisions for your environment.Explores the late

  3. Studies of Electrolytic Conductivity of Some Polyelectrolyte Solutions: Importance of the Dielectric Friction Effect at High Dilution

    Directory of Open Access Journals (Sweden)

    Anis Ghazouani

    2013-01-01

    Full Text Available We present a general description of conductivity behavior of highly charged strong polyelectrolytes in dilute aqueous solutions taking into account the translational dielectric friction on the moving polyions modeled as chains of charged spheres successively bounded and surrounded by solvent molecules. A general formal limiting expression of the equivalent conductivity of these polyelectrolytes is presented in order to distinguish between two concentration regimes and to evaluate the relative interdependence between the ionic condensation effect and the dielectric friction effect, in the range of very dilute solutions for which the stretched conformation is favored. This approach is illustrated by the limiting behaviors of three polyelectrolytes (sodium heparinate, sodium chondroitin sulfate, and sodium polystyrene sulphonate characterized by different chain lengths and by different discontinuous charge distributions.

  4. Liquid argon dielectric breakdown studies with the MicroBooNE purification system

    Energy Technology Data Exchange (ETDEWEB)

    Acciarri, R.; Carls, B.; James, C.; Johnson, B.; Jostlein, H.; Lockwitz, S.; Lundberg, B.; Raaf, J. L.; Rameika, R.; Rebel, B.; Zeller, G. P.; Zuckerbrot, M.

    2014-11-01

    The proliferation of liquid argon time projection chamber detectors makes the characterization of the dielectric properties of liquid argon a critical task. To improve understanding of these properties, a systematic study of the breakdown electric field in liquid argon was conducted using a dedicated cryostat connected to the MicroBooNE cryogenic system at Fermilab. An electrode sphere-plate geometry was implemented using spheres with diameters of 1.3 mm, 5.0 mm, and 76 mm. The MicroBooNE cryogenic system allowed measurements to be taken at a variety of electronegative contamination levels ranging from a few parts-per-million to tens of parts-per-trillion. The cathode-anode distance was varied from 0.1 mm to 2.5 cm. The results demonstrate a geometric dependence of the electric field strength at breakdown. This study is the first time that the dependence of the breakdown field on stressed cathode area has been shown for liquid argon.

  5. Effect of nanocomposite gate-dielectric properties on pentacene microstructure and field-effect transistor characteristics.

    Science.gov (United States)

    Lee, Wen-Hsi; Wang, Chun-Chieh

    2010-02-01

    In this study, the effect of surface energy and roughness of the nanocomposite gate dielectric on pentacene morphology and electrical properties of pentacene OTFT are reported. Nanoparticles TiO2 were added in the polyimide matrix to form a nanocomposite which has a significantly different surface characteristic from polyimide, leading to a discrepancy in the structural properties of pentacene growth. A growth mode of pentacene deposited on the nanocomposite is proposed to explain successfully the effect of surface properties of nanocomposite gate dielectric such as surface energy and roughness on the pentacene morphology and electrical properties of OTFT. To obtain the lower surface energy and smoother surface of nanocomposite gate dielectric that is responsible for the desired crystalline, microstructure of pentacene and electrical properties of device, a bottom contact OTFT-pentacene deposited on the double-layer nanocomposite gate dielectric consisting of top smoothing layer of the neat polyimide and bottom layer of (PI+ nano-TiO2 particles) nanocomposite has been successfully demonstrated to exhibit very promising performance including high current on to off ratio of about 6 x 10(5), threshold voltage of -10 V and moderately high filed mobility of 0.15 cm2V(-1)s(-1).

  6. Impedance spectroscopy of p-ZnGa{sub 2}Te{sub 4}/n-Si nano-HJD

    Energy Technology Data Exchange (ETDEWEB)

    Fouad, S.S. [Thin film Laboratory, Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Sakr, G.B. [Nano-Science Laboratory, Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Yahia, I.S., E-mail: dr_isyahia@yahoo.com [Nano-Science Laboratory, Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Semiconductor Laboratory, Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Abdel-Basset, D.M. [Nano-Science Laboratory, Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Yakuphanoglu, F. [Department of Physics, Faculty of Science, Firat University, Elazig (Turkey)

    2013-04-15

    The dielectric relaxation and alternating current mechanisms of nano-crystalline p-ZnGa{sub 2}Te{sub 4}/n-Si heterojunction diode (HJD) were investigated by complex impedance spectroscopy over a wide range of temperature (297–473 K) and a frequency range (42 Hz–5 MHz). The bulk resistance R{sub b} as well as the bulk capacitance C{sub b} were found to increase with increasing temperature. The dc conductivity exhibits a typical Arrhenius behavior. The electrical activation energy ΔE{sub σ} was determined to be (0.28 eV). The ac conductivity spectrum was found to obey Jonscher's universal power law. The frequency exponent s decreases slightly with increasing temperature. The temperature dependence of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping (CBH) model. The dielectric constant ε{sub 1}(ω) and dielectric loss ε{sub 2}(ω) were found to decrease with increasing frequency and to increase with increasing temperature. The mean value of the exponent m decreases with increasing temperature. The dielectric analysis is described by non-Debye type behavior.

  7. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    OpenAIRE

    Hullavarad, SS; Hullavarad, NV; Karulkar, PC; Luykx, A; Valdivia, P

    2007-01-01

    AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise a...

  8. Smart cover glass for automotive applications

    Science.gov (United States)

    Chung, Sang Kug

    2017-11-01

    This paper presents a smart cover glass based on electrowetting-on-dielectric (EWOD) actuation for automotive applications. It can remove water droplets in a wide range of sizes to allow the camera's lens to get clean at any time. The proposed cover glass offers a simple design structure to be easily installed on any device but provides a fast and energy efficient droplet cleaning operation. As proof of concept, a real imaging test is carried out using a mobile smartphone camera and landscape photography. When water droplets with different volumes are on the camera cover glass, the image of landscape photography is distorted with blurred spots. However, the distorted image is restored by removing the droplets through EWOD actuation.

  9. Electromagnetic illusion with isotropic and homogeneous materials through scattering manipulation

    International Nuclear Information System (INIS)

    Yang, Fan; Mei, Zhong Lei; Jiang, Wei Xiang; Cui, Tie Jun

    2015-01-01

    A new isotropic and homogeneous illusion device for electromagnetic waves is proposed. This single-shelled device can change the fingerprint of the covered object into another one by manipulating the scattering of the composite structure. We show that an electrically small sphere can be disguised as another small one with different electromagnetic parameters. The device can even make a dielectric sphere (electrically small) behave like a conducting one. Full-wave simulations confirm the performance of proposed illusion device. (paper)

  10. Single and dual fiber nano-tip optical tweezers: trapping and analysis

    OpenAIRE

    Decombe , Jean-Baptiste; Huant , Serge; Fick , Jochen

    2013-01-01

    International audience; An original optical tweezers using one or two chemically etched fiber nano-tips is developed. We demonstrate optical trapping of 1 micrometer polystyrene spheres at optical powers down to 2 mW. Harmonic trap potentials were found in the case of dual fiber tweezers by analyzing the trapped particle position fluctuations. The trap stiffness was deduced using three different models. Consistent values of up to 1 fN/nm were found. The stiffness linearly decreases with decre...

  11. Microwave electromagnetic properties of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coating

    International Nuclear Information System (INIS)

    Qing Yuchang; Zhou Wancheng; Luo Fa; Zhu Dongmei

    2010-01-01

    The electromagnetic characteristics of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coatings were studied. The reflection loss of the coatings exceeds -10 dB at 8-18 GHz and -9 dB at 2-18 GHz when the coating thickness is 1 and 3 mm, respectively. The dielectric and magnetic absorbers filled coatings possess excellent microwave absorption, which could be attributed to the proper incorporate of the multi-polarization mechanisms as well as strong natural resonance. It is feasible to develop the thin and wideband microwave absorbing coatings using carbonyl iron particles and Si/C/N nano-powder.

  12. Microwave electromagnetic properties of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coating

    Science.gov (United States)

    Qing, Yuchang; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

    2010-02-01

    The electromagnetic characteristics of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coatings were studied. The reflection loss of the coatings exceeds -10 dB at 8-18 GHz and -9 dB at 2-18 GHz when the coating thickness is 1 and 3 mm, respectively. The dielectric and magnetic absorbers filled coatings possess excellent microwave absorption, which could be attributed to the proper incorporate of the multi-polarization mechanisms as well as strong natural resonance. It is feasible to develop the thin and wideband microwave absorbing coatings using carbonyl iron particles and Si/C/N nano-powder.

  13. Observation of terahertz-radiation-induced ionization in a single nano island.

    Science.gov (United States)

    Seo, Minah; Kang, Ji-Hun; Kim, Hyo-Suk; Hyong Cho, Joon; Choi, Jaebin; Min Jhon, Young; Lee, Seok; Hun Kim, Jae; Lee, Taikjin; Park, Q-Han; Kim, Chulki

    2015-05-22

    Terahertz (THz) electromagnetic wave has been widely used as a spectroscopic probe to detect the collective vibrational mode in vast molecular systems and investigate dielectric properties of various materials. Recent technological advances in generating intense THz radiation and the emergence of THz plasmonics operating with nanoscale structures have opened up new pathways toward THz applications. Here, we present a new opportunity in engineering the state of matter at the atomic scale using THz wave and a metallic nanostructure. We show that a medium strength THz radiation of 22 kV/cm can induce ionization of ambient carbon atoms through interaction with a metallic nanostructure. The prepared structure, made of a nano slot antenna and a nano island located at the center, acts as a nanogap capacitor and enhances the local electric field by two orders of magnitudes thereby causing the ionization of ambient carbon atoms. Ionization and accumulation of carbon atoms are also observed through the change of the resonant condition of the nano slot antenna and the shift of the characteristic mode in the spectrum of the transmitted THz waves.

  14. ORGANIZATION IN CONTEMPORARY PUBLIC SPHERE

    Directory of Open Access Journals (Sweden)

    Rosemarie HAINES

    2013-12-01

    Full Text Available The critical analysis of Habermas’ Public Sphere Theory and the comparative undertaking to the current day enables us to assert that in contemporary society, public sphere is no longer a political public sphere, this dimension being completed by a societal dimension, the public sphere has extended and now we can talk about partial public spheres in an ever more commercial environment. The new rebuilding and communication technologies create a new type of public character: the visible sphere – non-located, non-dialogical and open. Information and communication are more and more involved in the restructuring of capitalism on an international scale and the reorganization of leadership and management systems. The reevaluation of the public sphere, public opinion, communication allows us to define public sphere according to the profound mutations from today’s democratic societies.

  15. Protein Nano-Object Integrator (ProNOI for generating atomic style objects for molecular modeling

    Directory of Open Access Journals (Sweden)

    Smith Nicholas

    2012-12-01

    Full Text Available Abstract Background With the progress of nanotechnology, one frequently has to model biological macromolecules simultaneously with nano-objects. However, the atomic structures of the nano objects are typically not available or they are solid state entities. Because of that, the researchers have to investigate such nano systems by generating models of the nano objects in a manner that the existing software be able to carry the simulations. In addition, it should allow generating composite objects with complex shape by combining basic geometrical figures and embedding biological macromolecules within the system. Results Here we report the Protein Nano-Object Integrator (ProNOI which allows for generating atomic-style geometrical objects with user desired shape and dimensions. Unlimited number of objects can be created and combined with biological macromolecules in Protein Data Bank (PDB format file. Once the objects are generated, the users can use sliders to manipulate their shape, dimension and absolute position. In addition, the software offers the option to charge the objects with either specified surface or volumetric charge density and to model them with user-desired dielectric constants. According to the user preference, the biological macromolecule atoms can be assigned charges and radii according to four different force fields: Amber, Charmm, OPLS and PARSE. The biological macromolecules and the atomic-style objects are exported as a position, charge and radius (PQR file, or if a default dielectric constant distribution is not selected, it is exported as a position, charge, radius and epsilon (PQRE file. As illustration of the capabilities of the ProNOI, we created a composite object in a shape of a robot, aptly named the Clemson Robot, whose parts are charged with various volumetric charge densities and holds the barnase-barstar protein complex in its hand. Conclusions The Protein Nano-Object Integrator (ProNOI is a convenient tool for

  16. Development of a High-performance Fluorpolymer Electret Mixed with Nano-particles and Its Application to Vibration Energy Harvesting

    International Nuclear Information System (INIS)

    Suzuki, M; Takahashi, T; Aoyagi, S

    2014-01-01

    We have been developing small power generation device of capacitance-type to be converted to electrical energy vibration energy using an electret. In this Study, dielectric nanoparticles were mixed with an electret made of fluorocarbon polymer. As a result, implanted charge density of the electret was successfully enhanced thanks to the mixing of particles. A small sized vibration energy harvester (VEH) was fabricated using the fluorocarbon mixed with dielectric nano-particles. As a result of applying vibration (20 Hz, 0.65 G) to the fabricated VEH, The maximum generated power of approximately 50 μW was obtained

  17. Comparison of three-dimensional poisson solution methods for particle-based simulation and inhomogeneous dielectrics.

    Science.gov (United States)

    Berti, Claudio; Gillespie, Dirk; Bardhan, Jaydeep P; Eisenberg, Robert S; Fiegna, Claudio

    2012-07-01

    Particle-based simulation represents a powerful approach to modeling physical systems in electronics, molecular biology, and chemical physics. Accounting for the interactions occurring among charged particles requires an accurate and efficient solution of Poisson's equation. For a system of discrete charges with inhomogeneous dielectrics, i.e., a system with discontinuities in the permittivity, the boundary element method (BEM) is frequently adopted. It provides the solution of Poisson's equation, accounting for polarization effects due to the discontinuity in the permittivity by computing the induced charges at the dielectric boundaries. In this framework, the total electrostatic potential is then found by superimposing the elemental contributions from both source and induced charges. In this paper, we present a comparison between two BEMs to solve a boundary-integral formulation of Poisson's equation, with emphasis on the BEMs' suitability for particle-based simulations in terms of solution accuracy and computation speed. The two approaches are the collocation and qualocation methods. Collocation is implemented following the induced-charge computation method of D. Boda et al. [J. Chem. Phys. 125, 034901 (2006)]. The qualocation method is described by J. Tausch et al. [IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 20, 1398 (2001)]. These approaches are studied using both flat and curved surface elements to discretize the dielectric boundary, using two challenging test cases: a dielectric sphere embedded in a different dielectric medium and a toy model of an ion channel. Earlier comparisons of the two BEM approaches did not address curved surface elements or semiatomistic models of ion channels. Our results support the earlier findings that for flat-element calculations, qualocation is always significantly more accurate than collocation. On the other hand, when the dielectric boundary is discretized with curved surface elements, the

  18. Advances in optoplasmonic sensors – combining optical nano/microcavities and photonic crystals with plasmonic nanostructures and nanoparticles

    Directory of Open Access Journals (Sweden)

    Xavier Jolly

    2018-01-01

    Full Text Available Nanophotonic device building blocks, such as optical nano/microcavities and plasmonic nanostructures, lie at the forefront of sensing and spectrometry of trace biological and chemical substances. A new class of nanophotonic architecture has emerged by combining optically resonant dielectric nano/microcavities with plasmonically resonant metal nanostructures to enable detection at the nanoscale with extraordinary sensitivity. Initial demonstrations include single-molecule detection and even single-ion sensing. The coupled photonic-plasmonic resonator system promises a leap forward in the nanoscale analysis of physical, chemical, and biological entities. These optoplasmonic sensor structures could be the centrepiece of miniaturised analytical laboratories, on a chip, with detection capabilities that are beyond the current state of the art. In this paper, we review this burgeoning field of optoplasmonic biosensors. We first focus on the state of the art in nanoplasmonic sensor structures, high quality factor optical microcavities, and photonic crystals separately before proceeding to an outline of the most recent advances in hybrid sensor systems. We discuss the physics of this modality in brief and each of its underlying parts, then the prospects as well as challenges when integrating dielectric nano/microcavities with metal nanostructures. In Section 5, we hint to possible future applications of optoplasmonic sensing platforms which offer many degrees of freedom towards biomedical diagnostics at the level of single molecules.

  19. S.H.A.S.T. and Tele-bio-sphere: Investigative Processes as Artistic Practices

    Directory of Open Access Journals (Sweden)

    Maria Luiza Fragoso

    2016-02-01

    Full Text Available The subjects herein addressed make part of a series of lectures and workshops developed by me along with the team of the New Organisms Art Nucleus (NANO during the last two years (2013-2015. So, examples of methodological processes applied in the various activities we have developed with undergraduate and graduate students will be presented. The importance I attach to these issues is directly related to the academic practice as well as to the artistic production derived from creation processes, aiming at systematizing and expanding knowledge in the realm of arts and technology, being all of it addressed from a cross-cultural approach. Thus I intend to bring some viewpoints that may feed the discussion between arts and sciences, from an experimental and trans-disciplinary approach, proposing the concepts of hybridity and bio-telematics, so as to illustrate the methodological procedures applied in the artistic projects S.H.A.S.T. and Tele-bio-sphere. http://nano.eba.ufrj.br

  20. Disclosed dielectric and electromechanical properties of hydrogenated nitrile–butadiene dielectric elastomer

    International Nuclear Information System (INIS)

    Yang, Dan; Tian, Ming; Dong, Yingchao; Liu, Haoliang; Yu, Yingchun; Zhang, Liqun

    2012-01-01

    This paper presents a comprehensive study of the effects of acrylonitrile content, crosslink density and plasticization on the dielectric and electromechanical performances of hydrogenated nitrile–butadiene dielectric elastomer. It was found that by increasing the acrylonitrile content of hydrogenated nitrile–butadiene dielectric elastomer, the dielectric constant will be improved accompanied with a sharp decrease of electrical breakdown strength leading to a small actuated strain. At a fixed electric field, a high crosslink density increased the elastic modulus of dielectric elastomer, but it also enhanced the electrical breakdown strength leading to a high actuated strain. Adding a plasticizer into the dielectric elastomer decreased the dielectric constant and electrical breakdown strength slightly, but reduced the elastic modulus sharply, which was beneficial for obtaining a large strain at low electric field from the dielectric elastomer. The largest actuated strain of 22% at an electric field of 30 kV mm −1 without any prestrain was obtained. Moreover, the hydrogenated nitrile–butadiene dielectric actuator showed good history dependence. This proposed material has great potential to be an excellent dielectric elastomer. (paper)

  1. Characterization of microstructured fibre emitters: in pursuit of improved nano electrospray ionization performance.

    Science.gov (United States)

    Wu, Xinyun; Oleschuk, Richard D; Cann, Natalie M

    2012-09-21

    Full-dimensional computational fluid dynamics (CFD) simulations are presented for nano electrospray ionization (ESI) with various emitter designs. Our CFD electrohydrodynamic simulations are based on the Taylor-Melcher leaky-dielectric model, and the volume of fluid technique for tracking the fast-changing liquid-gas interface. The numerical method is first validated for a conventional 20 μm inner diameter capillary emitter. The impact of ESI voltage, flow rate, emitter tapering, surface hydrophobicity, and fluid conductivity on the nano-ESI behavior are thoroughly investigated and compared with experiments. Multi-electrospray is further simulated with 2-hole and 3-hole emitters with the latter having a linear or triangular hole arrangement. The simulations predict multi-electrospray behavior in good agreement with laboratory observations.

  2. Synthesis and characterization of nano-hydroxyapatite using Sapindus Mukorossi extract

    Science.gov (United States)

    Subha, B.; Prasath, P. Varun; Abinaya, R.; Kavitha, R. J.; Ravichandran, K.

    2015-06-01

    Nano-Hydroxyapatite (HAP) powders were successfully synthesised by hydrothermal method using Sapindus Mukorossi extract as an additive. The structural and morphological analyses of thus synthesised powders were carried out using FT-IR, XRD and FESEM/EDX. The FT-IR spectra confirm the presence of phosphate and hydroxyl groups corresponding to HAP. The XRD analysis reveals the formation of HAP phase and found to reduce the crystallite size with addition of Sapindus Mukorossi extract. The morphology changes from sphere to flake shape by the influence of extract.

  3. Copper nano composites functionalized by bis-benzimidazole diamide ligand: Effect of size, co-anion dependent conductivity and band gap studies

    International Nuclear Information System (INIS)

    Singla, Manisha; Mohapatra, Subash Chandra; Ahmad, Sharif

    2012-01-01

    Copper (I) and copper (II) nano composites capped with a bis-benzimidazole diamide ligand were prepared by reverse micelle method and characterized using CHNS, FTIR, 1 H NMR, TEM and DLS studies. All particles were spherical ranging between 10 and 70 nm. They displayed a quasi reversible redox wave due to the Cu (II)/Cu (I) reduction process. The E g1 ′ values shift anodically as NO 3 − − − . Electrochemical HOMO and LUMO band gap (E g1 ′ ) for the nano composites were +1.80 (NO 3 − ), +2.80 (Cl − ) and +4.10 (SCN − ) eV, respectively. However, the optical band gap (E g1 ) for the nano composites was calculated from their absorption edges and lie between 1.77 and 4.13 eV. Fluorescence studies reveal that nano composites in themselves behave as an enhancer and quencher in respect to ligand, Quantum yield (φ) is varying from 0.008 to 0.02 photon. The activation energies range from 34 to 54 kJ mol −1 and are quite low in comparison to that of the free bis-benzimidazole diamide ligand (137 kJ mol −1 ). The lower activation energies further re-emphasize the nano size of these composites. At room temperature, the dc conductivity lies between 1 × 10 −4 –9.33 × 10 −4 S cm −1 [NO 3 − > SCN − > Cl − ] indicating them to be on the semiconductor insulator interface. The dielectric constant, dielectric loss and the ac conductivity were measured for all nano at room temperature and below the room temperature for the nano composite containing nitrate as co-anion. The conductivity was found to follow the correlated barrier hopping (CBH) mechanism; the exponent factor (s) varies from 0.5 to 1. -- Highlights: ► Nano composites of copper, capped by bis benzimidazole diamide ligand. ► Such copper nano composites have not been used in conductivity studies before. ► Conductance studies for these thus make this work unique. ► The dc conductivity of these composites is much higher than normal.

  4. Improvement microstructural and damage characterization of ceramic composites Y{sub 2}O{sub 3} – V{sub 2}O{sub 5} with MgO nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Issa, T. T., E-mail: alazbrh@yahoo.com; Hasan, J. M.; Abdullah, E. T. [University of Baghdad, College of Science, Physics Department, Jaderiha, Baghdad (Iraq); Shokr, F. S. [King Abdul Aziz Universit, Faculty of Science& Art, Physics Department, Rabigh, KSA (Saudi Arabia)

    2016-04-21

    Compacted samples of Y{sub 2}O{sub 3}-V{sub 2}O{sub 5} – MgO Nano – particles wt. % sintered at different sintering temperature (700, 900, 1100, 1300) ) C° for 2 hours under static air were investigated by x-ray diffraction and differential thermal analysis(DTA), to identify the phase present .Microstructure examination achieved by scanning electron microscopy .Sintered density and porosity were measured for all sintered samples .Compression was tested too and the Brake down voltage and dielectric strength were measure for all sintered samples .The clear improvement were noticed in both microstructure and damage characterization respectively after existing the MgO Nano-particles, by increasing in about 30% in sintered density and 25% for the compressive strength .The improvement also noticed on both brake down voltage and dielectric strength.

  5. Surface layer determination for the Si spheres of the Avogadro project

    Science.gov (United States)

    Busch, I.; Azuma, Y.; Bettin, H.; Cibik, L.; Fuchs, P.; Fujii, K.; Krumrey, M.; Kuetgens, U.; Kuramoto, N.; Mizushima, S.

    2011-04-01

    For the accurate determination of the Avogadro constant, two 28Si spheres were produced, whose macroscopic density, in addition to other values, must be determined. To make a contribution to the new definition of the kilogram, a relative standard uncertainty of less than 2 × 10-8 has to be achieved. Each silicon surface is covered by a surface layer (SL). Consequently, correction parameters for the SL are determined to be applied to the mass and volume determination of the enriched spheres. With the use of a large set of surface analysing techniques, the structure of the SL is investigated. An unexpected metallic contamination existing on the sphere surface enlarges the uncertainty contribution of the correction parameters above the originally targeted value of 1 × 10-8. In the framework of this investigation this new obstacle is resolved in two ways. A new combination of analytical methods is applied to measure the SL mass mSL and the thickness dSL, including this new contamination, with an uncertainty of u(mSL) = 14.5 µg and 14.4 µg, respectively, and u(dSL) = 0.33 nm and 0.32 nm for the 28Si spheres AVO28-S5 and AVO28-S8, respectively. In the second part of the work, the chemical composition of these metallic contaminations is found to be Cu, Ni and Zn silicide compounds. For the removal of this contamination, a special procedure is developed, tested and applied to the spheres to produce the originally expected surface structure on the spheres. After the application of this new procedure the use of x-ray reflectometry directly at the spheres will be possible. It is expected to reduce the uncertainty contribution due to the SL down to 1 × 10-8.

  6. Probing the equilibrium dynamics of colloidal hard spheres above the mode-coupling glass transition

    NARCIS (Netherlands)

    Brambilla, G.; al Masri, J.H.M.; Pierno, M.; Berthier, L.; Cipelletti, L.

    2010-01-01

    We use dynamic light scattering and computer simulations to study equilibrium dynamics and dynamic heterogeneity in concentrated suspensions of colloidal hard spheres. Our study covers an unprecedented density range and spans seven decades in structural relaxation time, , including equilibrium

  7. Effect of the out-of-plane stress on the properties of epitaxial SrTiO3 films with nano-pillar array on Si-substrate

    Science.gov (United States)

    Bai, Gang; Xie, Qiyun; Liu, Zhiguo; Wu, Dongmei

    2015-08-01

    A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO3 films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO3 films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO3 films similar to PZT and other lead-based ferroelectrics can be expected.

  8. Radiation induced nano structures

    International Nuclear Information System (INIS)

    Ibragimova, E.M.; Kalanov, M.U.; Khakimov, Z.

    2006-01-01

    Full text: Nanometer-size silicon clusters have been attracting much attention due to their technological importance, in particular, as promising building blocks for nano electronic and nano photonic systems. Particularly, silicon wires are of great of interest since they have potential for use in one-dimensional quantum wire high-speed field effect transistors and light-emitting devices with extremely low power consumption. Carbon and metal nano structures are studied very intensely due to wide possible applications. Radiation material sciences have been dealing with sub-micron objects for a long time. Under interaction of high energy particles and ionizing radiation with solids by elastic and inelastic mechanisms, at first point defects are created, then they form clusters, column defects, disordered regions (amorphous colloids) and finally precipitates of another crystal phase in the matrix. Such irradiation induced evolution of structure defects and phase transformations was observed by X-diffraction techniques in dielectric crystals of quartz and corundum, which exist in and crystal modifications. If there is no polymorphism, like in alkali halide crystals, then due to radiolysis halogen atoms are evaporated from the surface that results in non-stoichiometry or accumulated in the pores formed by metal vacancies in the sub-surface layer. Nano-pores are created by intensive high energy particles irradiation at first chaotically and then they are ordered and in part filled by inert gas. It is well-known mechanism of radiation induced swelling and embrittlement of metals and alloys, which is undesirable for construction materials for nuclear reactors. Possible solution of this problem may come from nano-structured materials, where there is neither swelling nor embrittlement at gas absorption due to very low density of the structure, while strength keeps high. This review considers experimental observations of radiation induced nano-inclusions in insulating

  9. Public Sphere

    DEFF Research Database (Denmark)

    Trenz, Hans-Jörg

    2015-01-01

    In modern societies, the public sphere represents the intermediary realm that supports the communication of opinions, the discovery of problems that need to be dealt with collectively, the channeling of these problems through the filter of the media and political institutions, and the realization...... of the collective will of the people in the act of democratic self-government. The concept of the public sphere is used across the fields of media and communication research, cultural studies and the humanities, the history of ideas, legal and constitutional studies as well as democracy studies. Historically......, public spheres have undergone structural transformations that were closely connected to the emergence of different mass media. More recently, they are subject to trends of transnationalization and digitalization in politics and society....

  10. Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications.

    Science.gov (United States)

    Rodríguez-Contreras, Alejandra; Marqués-Calvo, María Soledad; Gil, Francisco Javier; Manero, José María

    2016-08-01

    Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano- and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent.

  11. Nano Antenna Integrated Diode (Rectenna) For Infrared Energy Harvesting

    KAUST Repository

    Gadalla, Mena N.

    2013-01-01

    In this work full parametric analysis of nano antennas is presented. To begin with, optical or electronic properties of noble metals such as gold and copper were studied in details to get a clear understanding of their reaction to an incident electromagnetic wave. Complex frequency dependent dielectric functions indicated that in THz metals acts as a dielectric with significant absorption. Simultaneous optimization of the length and the bow angle of a bow-tie antenna resulted in relative electric field intensity enhancement of 8 orders of magnitude for 0.5nm gap and 4 orders of magnitude for 50nm around 28THz resonance frequency. These results are at least 2 orders of magnitude greater than the published optical antennas. Physical reasons behind field localization and intensity enhancement  are  discussed  in  details.  The  solution  of  Maxwell’s  equations  at   the  interface   between metallic nano antenna and air is also present in this piece of research. The derived dispersion relation of surface plasmons shows momentum matching at 28.3 THz between free propagating electromagnetic fields’ modes in air and localized modes at the interface. Consequently, Propagating electromagnetic waves are ensured to couple to localized surface propagating modes producing filed enhancement. The integrated matching section is theoretically proven to increase transmission to substrate to 75% (compared to 40% without it) which in turn improves the coupled power by 40 times. Nano antennas were fabricated in house using Electron beam lithography with a precise gap of 50nm. In addition, THz diode was designed, fabricated and integrated to the nano antennas to rectify the enhanced THz signal. The integration of the nano diode required a precise overlap of the two arms of the antenna in the rage of 100nm. In order to overcome two arms overlap fabrication challenges, three layer alignment technique was used to produce precise overlap.The THz rectifier was

  12. Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

    Directory of Open Access Journals (Sweden)

    A. Kanapitsas

    2016-03-01

    Full Text Available Composite systems of epoxy resin and barium ferrite nanoparticles have been prepared, and studied varying the content of the inclusions. Morphology of prepared samples has been examined via scanning electron microscopy and X-ray diffraction spectra, while electrical and magnetic properties were investigated by means of broadband dielectric spectroscopy, and magnetization tests respectively. Finally, water vapor sorption measurements were conducted in order to study the water sorption dynamics of the system. Electron microscopy images revealed the successful fabrication of nanocomposites. Dielectric permittivity increases with filler content, while three relaxation processes were detected in the relative spectra. These processes are attributed to interfacial polarization, glass to rubber transition of the matrix, and re-orientation of polar side groups of the polymer’s chain. Magnetization and magnetic saturation increase with magnetic nano-powder content. Nanocomposites absorb a small amount of water, not exceeding 1.7 wt%, regardless filler content, indicating their hydrophobic character.

  13. Progress in Nano-Electro-Optics III Industrial Applications and Dynamics of the Nano-Optical System

    CERN Document Server

    Ohtsu, Motoichi

    2005-01-01

    This unique monograph series "Progress in Nano-Electro Optics" reviews the results of advanced studies of electro-optics on the nanometric scale. This third volume covers the most recent topics of theoretical and experimental interest including classical and quantum optics, organic and inorganic material science and technology, surface science, spectroscopy, atom manipulation, photonics, and electronics. Each chapter is written by one or more leading scientists from the relevant field. Thus, high-quality scientific and technical information is provided to scientists, engineers, and students engaged in nano-electro optics and nanophotonics research. The first two volumes addressed the "Basics and Theory of Near Field Optics" (2002) and "Novel Devices and Atom Manipulation" (2003).

  14. Synthesis of Boron Nano wires, Nano tubes, and Nano sheets

    International Nuclear Information System (INIS)

    Patel, R.B.; Chou, T.; Iqbal, Z.

    2014-01-01

    The synthesis of boron nano wires, nano tubes, and nano sheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nano materials. The materials were made by using various combinations of MgB 2 , Mg(BH 4 ) 2 , MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nano wires, boron nano tubes, and boron nano sheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications.

  15. Low temperature fabrication of barium titanate hybrid films and their dielectric properties

    International Nuclear Information System (INIS)

    Kobayashi, Yoshio; Saito, Hirobumi; Kinoshita, Takafumi; Nagao, Daisuke; Konno, Mikio

    2011-01-01

    A method for incorporating BT nano-crystalline into barium titanate (BT) films is proposed for a low temperature fabrication of high dielectric constant films. BT nanoparticles were synthesized by hydrolysis of a BT complex alkoxide in 2-methoxyethanol (ME)/ethanol cosolvent. As the ME volume fraction in the cosolvent (ME fraction) increased from 0 to 100%, the particle and crystal sizes tended to increase from 13.4 to 30.2 nm and from 15.8 to 31.4 nm, respectively, and the particle dispersion in the solution became more improved. The BT particles were mixed with BT complex alkoxide dissolved in an ME/ethanol cosolvent for preparing a precursor solution that was then spin-coated on a Pt substrate and dried at 150 o C. The dielectric constant of the spin-coated BT hybrid film increased with an increase in the volume fraction of the BT particles in the film. The dissipation factor of the hybrid film tended to decrease with an increase in the ME fraction in the precursor solution. The hybrid film fabricated at a BT fraction of 30% and an ME fraction of 25% attained a dielectric constant as high as 94.5 with a surface roughness of 14.0 nm and a dissipation factor of 0.11.

  16. Magnetic response from a composite of metal-dielectric particles in the visible range: T-matrix simulation

    Directory of Open Access Journals (Sweden)

    O. Zhuromskyy

    2011-09-01

    Full Text Available The optical response of a particle composed of a dielectric core surrounded by a densely packed shell of small metal spheres is simulated with the superposition Tmatrix method for realistic material parameters. In order to compute the electric and magnetic particle polarizabilities a single expansion T-matrix is derived from a particle centered T-matrix. Finally the permeability of a medium comprising such particles is found to deviate considerable from unity resulting in a noticeable optical response.

  17. Flat dielectric metasurface lens array for three dimensional integral imaging

    Science.gov (United States)

    Zhang, Jianlei; Wang, Xiaorui; Yang, Yi; Yuan, Ying; Wu, Xiongxiong

    2018-05-01

    In conventional integral imaging, the singlet refractive lens array limits the imaging performance due to its prominent aberrations. Different from the refractive lens array relying on phase modulation via phase change accumulated along the optical paths, metasurfaces composed of nano-scatters can produce phase abrupt over the scale of wavelength. In this letter, we propose a novel lens array consisting of two neighboring flat dielectric metasurfaces for integral imaging system. The aspherical phase profiles of the metasurfaces are optimized to improve imaging performance. The simulation results show that our designed 5 × 5 metasurface-based lens array exhibits high image quality at designed wavelength 865 nm.

  18. SURFACES OF HARD-SPHERE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Dietrich Stoyan

    2014-07-01

    Full Text Available In various situations surfaces appear that are formed by systems of hard spheres. Examples are porous layers as surfaces of sand heaps and biofilms or fracture surfaces of concrete. The present paper considers models where a statistically homogeneous system of hard spheres with random radii is intersected by a plane and the surface is formed by the spheres with centers close to this plane. Formulae are derived for various characteristics of such surfaces: for the porosity profile, i.e. the local porosity in dependence on the distance from the section plane and for the geometry of the sphere caps that look above the section plane.It turns out that these characteristics only depend on the first-order characteristics of the sphere system, its sphere density and the sphere radius distribution.Comparison with empirically studied biofilms shows that the model is realistic.

  19. Assessing the plasmonics of gold nano-triangles with higher order laser modes

    Directory of Open Access Journals (Sweden)

    Laura E. Hennemann

    2012-10-01

    Full Text Available Regular arrays of metallic nano-triangles – so called Fischer patterns – are fabricated by nano-sphere lithography. We studied such gold nano-triangle arrays on silicon or glass substrates. A series of different samples was investigated with a parabolic mirror based confocal microscope where the sample is scanned through the laser focus. By employing higher order laser modes (azimuthally and radially polarised laser beams, we can excite the Fischer patterns using either a pure in-plane (x,y electric field or a strongly z-directional (optical axis of the optical microscope electric field. We collected and evaluated the emitted luminescence and thereby investigated the respectively excited plasmonic modes. These varied considerably: firstly with the light polarisation in the focus, secondly with the aspect ratio of the triangles and thirdly with the employed substrate. Moreover, we obtained strongly enhanced Raman spectra of an adenine (sub-monolayer on gold Fischer patterns on glass. We thus showed that gold Fischer patterns are promising surface-enhanced Raman scattering (SERS substrates.

  20. Fabrication of Pt/Au concentric spheres from triblock copolymer.

    Science.gov (United States)

    Koh, Haeng-Deog; Park, Soojin; Russell, Thomas P

    2010-02-23

    Dispersion of an aqueous H(2)PtCl(6) solution into a trifluorotoluene (TFT) solution of a polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymer produced an emulsion-induced hollow micelle (EIHM), comprising a water nanodroplet stabilized by PEO, H(2)PtCl(6)/P2VP, and PS, sequentially. The following addition of an aqueous LiAuCl(4) solution into the dispersion led to a coordination of LiAuCl(4) and PEO. The resulting spherical EIHM structure was transformed to a hollow cylindrical micelle by the fusion of spherical EIHM with the addition of methanol. This structural transition was reversible by the alternative addition of methanol and TFT. Oxygen plasma was used to generate Pt/Au concentric spheres and hollow cylindrical Pt/Au nano-objects.

  1. Influence of Zn doping on structural, optical and dielectric properties of LaFeO3

    Science.gov (United States)

    Manzoor, Samiya; Husain, Shahid

    2018-05-01

    The effect of Zn doping on structural, optical and dielectric properties of nano-crystalline LaFe1‑xZnxO3 (0.0 ≤ x ≤ 0.3) samples have been investigated. These samples are synthesized using conventional solid state reaction route. X-ray diffraction patterns with Rietveld analysis confirm the single phase nature of samples. Further, the sample formation has been confirmed by FTIR spectroscopy. All the samples are formed in orthorhombic crystal symmetry with Pbnm space group. The average crystallite sizes, calculated from the Scherer’s formula, lie in the range below 50 nm. Rietveld refinement technique is used to determine lattice parameters, bond lengths and unit cell volume. Williamson-Hall analysis has been performed to calculate the crystallite size and lattice strain. Crystallite sizes are found to be of nanometer range while the strain is of the order of 10‑3. Zn doping leads to the expansion of volume due to the tensile strain. Optical bandgap has been determined from Kubelka-Munk function using Tauc’s relation. Zinc doping in LaFeO3 leads to decrease in optical bandgap. Dielectric constant as a function of frequency is measured in the frequency range of 75 kHz–5 MHz. The dielectric behavior has been investigated by analyzing ‘universal dielectric response’ (UDR) model. The dielectric constant (ε‧) shows colossal value with Zn doping in the whole frequency range. However, the imaginary part (ε″) shows relaxational behavior which may be attributed to the strong correlation that exists between conduction mechanism and dielectric behavior in ferrites. Cole-Cole analysis has been done that confirms the dielectric material does not follow the ideal Debye theory but shows distribution of relaxation times. The a.c conductivity increases with frequency and with Zn doping due to the increased polaron hopping.

  2. Dermal transfer quantification of nanoparticles from nano-enabled surfaces

    DEFF Research Database (Denmark)

    Mackevica, Aiga; Olsson, Mikael Emil; Mines, Paul D.

    2018-01-01

    ). The dermal transfer testing by wipe sampling and analytical approach used in this study demonstrates that wipe testing in combination with spICP-MS analysis can provide both qualitative data in terms of mass and number-based NP release, as well as particle characterization in terms of NP size distribution...... and characterize NP release from keyboard covers and freshly painted surfaces, in terms of mass and number concentration, as well as released particle size distribution through the use of spICP-MS. Three types of NPs were selected for method validation testing, Ag, TiO2, and CuO; and, the particle extraction from...... wipes was found to be efficient for Ag and CuO, but not for TiO2 particles. Thereafter, potential dermal transfer was tested by wipe sampling for two nanoAg-containing silicon keyboard covers, and wood painted with nanoCuO-containing paint. AgNP release was observed for one of the keyboard cover types...

  3. Microwave properties of sphere-, flake-, and disc-shaped BaFe12O19 nanoparticle inks for high-frequency applications on printed electronics

    International Nuclear Information System (INIS)

    Myllymäki, S.; Maček Kržmanc, M.; Sloma, M.; Juuti, J.; Nelo, M.; Teirikangas, M.; Jakubowska, M.; Suvorov, D.; Jantunen, H.

    2016-01-01

    Spherical (diameter 50–200 nm), flake- (diameter 40–200 nm), and disc-shaped (diameter 10–20 nm) BaFe 12 O 19 nanoparticles were synthesized with a wet chemical method, and their permittivity, electric loss tangent, permeability, and magnetic loss tangent were measured in the 0.045–10 GHz range. The materials were prepared using a solution of 12% PMMA resin in a butyldiglycol solvent for 10–50 wt% filling content. Microstrip transmission-line perturbation was used to measure complex permeability and the split post dielectric resonator method was employed to measure dielectric properties. The frequency dependence of the permeability and permittivity spectra of the composites was affected by their shape and filling fraction. The composites made with spherical particles had higher permeability values (1.4–1.75) at 1 GHz than the composites made with flake (1.25–1.6) or disc particles (1.1–1.3), but the spherical particles caused more losses. The flake particle composite provided permeability and magnetic loss characteristics at both 1 GHz and 7 GHz superior to those of the sphere particle composite in low-loss RF applications. The magnetic loss tangent of PMMA/BaFe 12 O 19 was 0.2–0.3 at 1 GHz, being lower than that of state-of-the-art PANI/BaFe 12 O 19 composites. The sphere composite inks showed permeability values less than 1 at 1–4 GHz ferromagnetic resonance (FMR); they could be used as a tunable material in microwave applications. The sphere and flake composite inks also had sufficient printing quality for the screen-printing fabrication method.

  4. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    Directory of Open Access Journals (Sweden)

    Luykx A

    2007-01-01

    Full Text Available AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise and decay time measurements were also measured.

  5. Comparative evaluation of hydroxyapatite and nano-bioglass in two forms of conventional micro- and nano-particles in repairing bone defects (an animal study).

    Science.gov (United States)

    Nosouhian, Saied; Razavi, Mohammad; Jafari-Pozve, Nasim; Rismanchian, Mansour

    2015-01-01

    Many synthetic bone materials have been introduced for repairing bone defects. The aim of this study is to comparatively evaluate the efficacy of nano-hydroxyapatite (HA) and nano-bioglass bone materials with their traditional micro counterparts in repairing bone defects. In this prospective animal study, four healthy dogs were included. First to fourth premolars were extracted in each quadrant and five cavities in each quadrant were created using trephine. Sixteen cavities in each dog were filled by HA, nano-HA, bioglass, and nano-bioglass and four defects were left as the control group. All defects were covered by a nonrestorable membrane. Dogs were sacrificed after 15, 30, 45, and 60 days sequentially. All 20 samples were extracted by trephine #8 with a sufficient amount of surrounding bone. All specimens were investigated under an optical microscope and the percentage of total regenerated bone, lamellar, and woven bone were evaluated. Data analysis was carried out by SPSS Software ver. 15 and Mann-Whitney U-test (α =0.05). After 15 days, the bone formation percentage showed a significant difference between HA and nano-HA and between HA and bioglass (P bone formation after 15 days. Nano-bioglass and bioglass and nano-HA and nano-bioglass groups represented a significant difference and nano-bioglass showed the highest rate of bone formation after 30 days (P = 0.01). After 45 days, the bone formation percentage showed a significant difference between nano-bioglass and bioglass and between nano-HA and nano-bioglass groups (P = 0.01). Nano-HA and nano-bioglass biomaterials showed promising results when compared to conventional micro-particles in the repair of bone defects.

  6. Evaluation on the toxicity of nanoAg to bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Liu Rutao, E-mail: rutaoliu@sdu.edu.cn [School of Environmental Science and Engineering, Shandong University, 27 Shanda South Road, Jinan 250100 (China); Sun Feng; Zhang Lijun; Zong Wansong; Zhao Xingchen; Wang Li; Wu Ruolin [School of Environmental Science and Engineering, Shandong University, 27 Shanda South Road, Jinan 250100 (China); Hao Xiaopeng [State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 (China)

    2009-06-15

    Measuring protein damage by nanomaterials may give insight into the mechanisms of toxicity of nanomaterials. The toxic effects of nanoAg on bovine serum albumin (BSA) were thoroughly studied using fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, resonance light scattering spectroscopy (RLS), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM). NanoAg had obvious toxic effects on BSA: nanoAg could increase the amount of helix and decrease the beta sheet structure, leading to a loosening of the protein skeleton. In the loose structure, internal hydrophobic amino acids are exposed and the characteristic fluorescence of BSA is obviously quenched. When the ratio of nanoAg and BSA increased to 1: 96 (wt/wt), the impact of nanoAg on the spectral properties leveled off. The RLS spectrum, TEM, CD spectra and electrophoresis results showed that BSA had destroyed the double-layer structure of nanoAg and covered its surface, generating a BSA-nanoAg complex held together by van der Waals and electrostatic forces. This paper provides a new perspective and method for determining the toxic effects of nanoAg on biological macromolecules.

  7. Nano-technology and nano-toxicology.

    Science.gov (United States)

    Maynard, Robert L

    2012-01-01

    Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of exposure to nano-materials and relates these to the evidence of the effects on health of the ambient aerosol. A number of hypotheses are proposed and the dangers of adopting unsubstantiated hypotheses are stressed. Nano-toxicology presents many challenges and will need substantial financial support if it is to develop at a rate sufficient to cope with developments in nano-technology.

  8. Computation of Dielectric Response in Molecular Solids for High Capacitance Organic Dielectrics.

    Science.gov (United States)

    Heitzer, Henry M; Marks, Tobin J; Ratner, Mark A

    2016-09-20

    The dielectric response of a material is central to numerous processes spanning the fields of chemistry, materials science, biology, and physics. Despite this broad importance across these disciplines, describing the dielectric environment of a molecular system at the level of first-principles theory and computation remains a great challenge and is of importance to understand the behavior of existing systems as well as to guide the design and synthetic realization of new ones. Furthermore, with recent advances in molecular electronics, nanotechnology, and molecular biology, it has become necessary to predict the dielectric properties of molecular systems that are often difficult or impossible to measure experimentally. In these scenarios, it is would be highly desirable to be able to determine dielectric response through efficient, accurate, and chemically informative calculations. A good example of where theoretical modeling of dielectric response would be valuable is in the development of high-capacitance organic gate dielectrics for unconventional electronics such as those that could be fabricated by high-throughput printing techniques. Gate dielectrics are fundamental components of all transistor-based logic circuitry, and the combination high dielectric constant and nanoscopic thickness (i.e., high capacitance) is essential to achieving high switching speeds and low power consumption. Molecule-based dielectrics offer the promise of cheap, flexible, and mass producible electronics when used in conjunction with unconventional organic or inorganic semiconducting materials to fabricate organic field effect transistors (OFETs). The molecular dielectrics developed to date typically have limited dielectric response, which results in low capacitances, translating into poor performance of the resulting OFETs. Furthermore, the development of better performing dielectric materials has been hindered by the current highly empirical and labor-intensive pace of synthetic

  9. Enhanced biomimic bactericidal surfaces by coating with positively-charged ZIF nano-dagger arrays.

    Science.gov (United States)

    Yuan, Yuan; Zhang, Yugen

    2017-10-01

    Cicada wing surfaces are covered with dense patterns of nano-pillar structure that prevent bacterial growth by rupturing adhered microbial cells. To mimic the natural nano-pillar structure, we developed a general and simple method to grow metal organic framework (MOF) nano-dagger arrays on a wide range of surfaces. These nano-daggers possess high bactericidal activity, with log reduction >7 for Escherichia coli and Staphylococcus aureus. It was hypothesized that the positively-charged ZIF-L nano-dagger surfaces enhance bacterial cell adhesion, facilitating selective and efficient bacteria killing by the rigid and sharp nano-dagger tips. This research provides a safe and clean antimicrobial surface technology which does not require external chemicals and will not cause drug resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Single and dual fiber nano-tip optical tweezers: trapping and analysis.

    Science.gov (United States)

    Decombe, Jean-Baptiste; Huant, Serge; Fick, Jochen

    2013-12-16

    An original optical tweezers using one or two chemically etched fiber nano-tips is developed. We demonstrate optical trapping of 1 micrometer polystyrene spheres at optical powers down to 2 mW. Harmonic trap potentials were found in the case of dual fiber tweezers by analyzing the trapped particle position fluctuations. The trap stiffness was deduced using three different models. Consistent values of up to 1 fN/nm were found. The stiffness linearly decreases with decreasing light intensity and increasing fiber tip-to-tip distance.

  11. Investigation of dielectric breakdown in silica-epoxy nanocomposites using designed interfaces.

    Science.gov (United States)

    Bell, Michael; Krentz, Timothy; Keith Nelson, J; Schadler, Linda; Wu, Ke; Breneman, Curt; Zhao, Su; Hillborg, Henrik; Benicewicz, Brian

    2017-06-01

    Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistry on the AC dielectric breakdown strength of silica-epoxy nanocomposites. Ligand engineering was used to synthesize bimodal ligands onto 15nm silica nanoparticles consisting of long epoxy compatible, poly(glycidyl methacrylate) (PGMA) chains, and short, π-conjugated, electroactive surface ligands. Surface initiated RAFT polymerization was used to synthesize multiple graft densities of PGMA chains, ultimately controlling the dispersion of the filler. Thiophene, anthracene, and terthiophene were employed as π-conjugated surface ligands that act as electron traps to mitigate avalanche breakdown. Investigation of the synthesized multifunctional nanoparticles was effective in defining the maximum particle spacing or free space length (L f ) that still leads to property enhancement, as well as giving insight into the effects of varying the electronic nature of the molecules at the interface on breakdown strength. Optimization of the investigated variables was shown to increase the AC dielectric breakdown strength of epoxy composites as much as 34% with only 2wt% silica loading. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Manufacturing Steps for Commercial Production of Nano-Structure Capacitors Final Report CRADA No. TC02159.0

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schena, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-29

    This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and TroyCap LLC, to develop manufacturing steps for commercial production of nano-structure capacitors. The technical objective of this project was to demonstrate high deposition rates of selected dielectric materials which are 2 to 5 times larger than typical using current technology.

  13. On the Impact of Spheres onto Liquid Pools and Ultra-viscous Films

    KAUST Repository

    Mansoor, Mohammad Mujtaba

    2016-06-01

    The free-surface impact of spheres is important to several applications in the military, industry and sports such as the water-entry of torpedoes, dip-coating procedures and slamming of boats. This two-part thesis attempts to explore this field by investigating cavity formation during the impact of spheres with deep liquid pools and cavitation in thin ultra-viscous films. Part I reports results from an experimental study on the formation of stable- streamlined and helical cavity wakes following the free-surface impact of heated Leidenfrost spheres. The Leidenfrost effect encapsulates the sphere by a vapor layer to prevent any physical contact with the surrounding liquid. This phenomenon is essential for the pacification of acoustic rippling along the cavity interface to result in a stable-streamlined cavity wake. Such a streamlined configuration experiences drag coefficients an order of magnitude lower than those acting on room temperature spheres. A striking observation is the formation of helical cavities which occur for impact Reynolds numbers 0 ≳ 1.4 × 105 and are characterized by multiple interfacial ridges, stemming from and rotating synchronously about an evident contact line around the sphere equator. This helical configuration has 40-55% smaller overall force coefficients than those obtained in the formation of stable cavity wakes. Part II of this thesis investigates the inception of cavitation and resulting structures when a sphere collides with a solid surface covered with a layer of non-Newtonian liquid having kinematic viscosities of up to 0 = 20,000,000 cSt. The existence of shear-stress- induced cavitation during sphere approach towards the base wall (i.e. the pressurization stage) in ultra-viscous films is shown using a synchronized dual-view high-speed imaging system. In addition, cavitation by depressurization is noted for a new class of non-contact cases whereby the sphere rebounds without any prior contact with the solid wall. Horizontal

  14. Surface Plasmon-Mediated Nanoscale Localization of Laser-Driven sub-Terahertz Spin Dynamics in Magnetic Dielectrics

    Science.gov (United States)

    Chekhov, Alexander L.; Stognij, Alexander I.; Satoh, Takuya; Murzina, Tatiana V.; Razdolski, Ilya; Stupakiewicz, Andrzej

    2018-05-01

    Ultrafast all-optical control of spins with femtosecond laser pulses is one of the hot topics at the crossroads of photonics and magnetism with a direct impact on future magnetic recording. Unveiling light-assisted recording mechanisms for an increase of the bit density beyond the diffraction limit without excessive heating of the recording medium is an open challenge. Here we show that surface plasmon-polaritons in hybrid metal-dielectric structures can provide spatial confinement of the inverse Faraday effect, mediating the excitation of localized coherent spin precession with 0.41 THz frequency. We demonstrate a two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within the 100 nm layer in dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways towards non-thermal opto-magnetic recording at the nano-scale.

  15. Dielectric and electrical characteristics of Sr modified Ca1Cu3Ti4O12

    Science.gov (United States)

    Sahu, M.; Choudhary, R. N. P.; Roul, B. K.

    2018-05-01

    This paper mainly reports on the effect of Sr substitution on dielectric and electrical properties of CaCu3Ti4O12 at different temperature and frequency. Preliminary analysis of X-ray diffraction data of sintered samples confirms the reported cubic structure. Study of surface morphology shows that the surface of the samples contains well-defined and uniformly distributed grains. Some electrical parameters (permittivity, tangent loss and impedance) of the materials were measured and analyzed over a wide range of temperature (25 to 315 °C) and frequency (50 to 2x106 Hz). The ultra high dielectric constant and low energy dissipation have been observed in the said experimental conditions of phase-pure prepared compounds. It is expected that the addition of nano-size compounds or oxide will help to enhance the above properties useful for fabrication of super-capacitor.

  16. Selected Topics in MicroNano-robotics for Biomedical Applications

    CERN Document Server

    2013-01-01

    Selected Topics in Micro/Nano-robotics for Biomedical Applications features a system approach and incorporates modern methodologies in autonomous mobile robots for programmable and controllable micro/nano-robots aiming at biomedical applications. The book provides chapters of instructional materials and cutting-edge research results in micro/nanorobotics for biomedical applications. The book presents new sensing technology on nanofibers, new power supply techniques including miniature fuel cells and energy harvesting devices, and manipulation techniques including AFM-based nano-robotic manipulation, robot-aided optical tweezers, and robot-assisted catheter surgery systems. It also contains case studies on using micro/nano-robots in biomedical environments and in biomedicine, as well as a design example to conceptually develop a Vitamin-pill sized robot to enter human’s gastrointestinal tract. Each chapter covers a different topic of the highly interdisciplinary area. Bring together the selected topics into ...

  17. Homogeneous dielectric barrier discharges in atmospheric air and its influencing factor

    Science.gov (United States)

    Ran, Junxia; Li, Caixia; Ma, Dong; Luo, Haiyun; Li, Xiaowei

    2018-03-01

    The stable homogeneous dielectric barrier discharge (DBD) is obtained in atmospheric 2-3 mm air gap. It is generated using center frequency 1 kHz high voltage power supply between two plane parallel electrodes with specific alumina ceramic plates as the dielectric barriers. The discharge characteristics are studied by a measurement of its electrical discharge parameters and observation of its light emission phenomena. The results show that a large single current pulse of about 200 μs duration appearing in each voltage pulse, and its light emission is radially homogeneous and covers the entire surface of the two electrodes. The homogeneous discharge generated is a Townsend discharge during discharge. The influences of applied barrier, its thickness, and surface roughness on the transition of discharge modes are studied. The results show that it is difficult to produce a homogeneous discharge using smooth plates or alumina plate surface roughness Ra material, dielectric thickness, and dielectric surface roughness should be used, and proper applied voltage amplitude and frequency should also be used.

  18. Analytic functionals on the sphere

    CERN Document Server

    Morimoto, Mitsuo

    1998-01-01

    This book treats spherical harmonic expansion of real analytic functions and hyperfunctions on the sphere. Because a one-dimensional sphere is a circle, the simplest example of the theory is that of Fourier series of periodic functions. The author first introduces a system of complex neighborhoods of the sphere by means of the Lie norm. He then studies holomorphic functions and analytic functionals on the complex sphere. In the one-dimensional case, this corresponds to the study of holomorphic functions and analytic functionals on the annular set in the complex plane, relying on the Laurent series expansion. In this volume, it is shown that the same idea still works in a higher-dimensional sphere. The Fourier-Borel transformation of analytic functionals on the sphere is also examined; the eigenfunction of the Laplacian can be studied in this way.

  19. Nano technology

    International Nuclear Information System (INIS)

    Lee, In Sik

    2002-03-01

    This book is introduction of nano technology, which describes what nano technology is, alpha and omega of nano technology, the future of Korean nano technology and human being's future and nano technology. The contents of this book are nano period is coming, a engine of creation, what is molecular engineering, a huge nano technology, technique on making small things, nano materials with exorbitant possibility, the key of nano world the most desirable nano technology in bio industry, nano development plan of government, the direction of development for nano technology and children of heart.

  20. MoS2 coated hollow carbon spheres for anodes of lithium ion batteries

    International Nuclear Information System (INIS)

    Zhang, Yufei; Wang, Ye; Shi, Wenhui; Yang, Huiying; Yang, Jun; Huang, Wei; Dong, Xiaochen

    2016-01-01

    With the assistance of resorcinol–formaldehyde, MoS 2 coated hollow carbon spheres (C@MoS 2 ) were synthesized through a facile hydrothermal route followed by heat and alkali treatments. The measurements indicate that the hollow carbon spheres with an average diameter of 300 nm and shell thickness of 20 nm. And the hollow core are uniformly covered by ultrathin MoS 2 nanosheets with a length increased to 400 nm. The unique hollow structure and the synergistic effect between carbon layer and MoS 2 nanosheets significantly enhance the rate capability and electrochemical stability of C@MoS 2 spheres as anode material of lithium-ion battery. The synthesized C@MoS 2 delivered a capacity of 750 mAh g −1 at a current density of 100 mA g −1 . More importantly, the C@MoS 2 maintained a reversible capacity of 533 mAh g −1 even at a high current density of 1000 mA g −1 . The study indicated that MoS 2 coated hollow carbon spheres can be promising anode material for next generation high-performance lithium-ion batteries. (paper)

  1. Effect of the out-of-plane stress on the properties of epitaxial SrTiO{sub 3} films with nano-pillar array on Si-substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Gang, E-mail: baigang@njupt.edu.cn [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Xie, Qiyun [Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging and College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Liu, Zhiguo [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wu, Dongmei [School of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China)

    2015-08-21

    A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO{sub 3} films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO{sub 3} films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO{sub 3} films similar to PZT and other lead-based ferroelectrics can be expected.

  2. Micro/Nano manufacturing

    DEFF Research Database (Denmark)

    Tosello, Guido

    2017-01-01

    Micro- and nano-scale manufacturing has been the subject of an increasing amount of interest and research effort worldwide in both academia and industry over the past 10 years.Traditional (MEMS) manufacturing, but also precision manufacturing technologies have been developed to cover micro......-scale dimensions and accuracies. Furthermore, these fundamentally different technology ecosystems are currently combined in order to exploit strengths of both platforms. One example is the use of lithography-based technologies to establish nanostructures that are subsequently transferred to 3D geometries via...

  3. Gold nano-particles fixed on glass

    International Nuclear Information System (INIS)

    Worsch, Christian; Wisniewski, Wolfgang; Kracker, Michael; Rüssel, Christian

    2012-01-01

    Highlights: ► We produced wear resistant gold–ruby coatings on amorphous substrates. ► Thin sputtered gold layers were covered by or embedded in silica coatings. ► Annealing above T g of the substrate glass led to the formation of gold nano particles. ► A 1 1 1-texture of the gold particles is observed via XRD and EBSD. ► EBSD-patterns can be acquired from crystals covered by a thin layer of glass. - Abstract: A simple process for producing wear resistant gold nano-particle coatings on transparent substrates is proposed. Soda-lime-silica glasses were sputtered with gold and subsequently coated with SiO 2 using a combustion chemical vapor deposition technique. Some samples were first coated with silica, sputtered with gold and then coated with a second layer of silica. The samples were annealed for 20 min at either 550 or 600 °C. This resulted in the formation of round, well separated gold nano-particles with sizes from 15 to 200 nm. The color of the coated glass was equivalent to that of gold–ruby glasses. Silica/gold/silica coatings annealed at 600 °C for 20 min were strongly adherent and scratch resistant. X-ray diffraction and electron backscatter diffraction (EBSD) were used to describe the crystal orientations of the embedded particles. The gold particles are preferably oriented with their (1 1 1) planes perpendicular to the surface.

  4. Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

    International Nuclear Information System (INIS)

    Paddubskaya, A.; Valynets, N.; Batrakov, K.; Kuzhir, P.; Maksimenko, S.; Kotsilkova, R.; Velichkova, H.; Petrova, I.; Biró, I.; Kertész, K.; Márk, G. I.; Horváth, Z. E.; Biró, L. P.

    2016-01-01

    A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structural characteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic material for electromagnetic compatibility applications in microwave frequency range. Sandwich structures containing only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8–15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.

  5. Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

    Energy Technology Data Exchange (ETDEWEB)

    Paddubskaya, A. [Research Institute for Nuclear Problems, Belarusian State University, Bobruiskaya Str. 11, 220030 Minsk (Belarus); Center for Physical Sciences and Technology, A. Goštauto 11, LT-01108 Vilnius (Lithuania); Valynets, N.; Batrakov, K. [Research Institute for Nuclear Problems, Belarusian State University, Bobruiskaya Str. 11, 220030 Minsk (Belarus); Kuzhir, P., E-mail: polina.kuzhir@gmail.com; Maksimenko, S. [Research Institute for Nuclear Problems, Belarusian State University, Bobruiskaya Str. 11, 220030 Minsk (Belarus); Tomsk State University, Tomsk 634050 (Russian Federation); Kotsilkova, R.; Velichkova, H.; Petrova, I. [Open Laboratory on Experimental Micro and Nano Mechanics, Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 4, Sofia (Bulgaria); Biró, I. [3D Wishes, Bíró u. 44/a/2, Érd (Hungary); Kertész, K.; Márk, G. I.; Horváth, Z. E.; Biró, L. P. [Institute of Technical Physics and Materials Science, Centre for Energy Research, PO Box 49, 1525 Budapest (Hungary)

    2016-04-07

    A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structural characteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic material for electromagnetic compatibility applications in microwave frequency range. Sandwich structures containing only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8–15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.

  6. Mechanics over micro and nano scales

    CERN Document Server

    Chakraborty, Suman

    2011-01-01

    Discusses the fundaments of mechanics over micro and nano scales in a level accessible to multi-disciplinary researchers, with a balance of mathematical details and physical principles Covers life sciences and chemistry for use in emerging applications related to mechanics over small scales Demonstrates the explicit interconnection between various scale issues and the mechanics of miniaturized systems

  7. Exergy analysis of the solar still integrated nano composite phase change materials

    International Nuclear Information System (INIS)

    Methre, V.K.; Eswaramoorthy, M.

    2015-01-01

    This paper communicates the exergy analysis of solar still integrated with nano composite phase change materials for design and operating parameters. Al_2O_3 nano materials (50 nm) is dispersed by weight ratio in paraffin wax at melting state and its thermophysical properties are evaluated using developed correlation. Exergy balance equation for basin liner, thermal energy storage, glass cover and saline water is developed and exergy efficiency is analysed. It is found that exergy efficiency is improved by higher weight ratio of Al_2O_3 nano materials with paraffin wax alone. (author)

  8. FDTD simulations and analysis of thin sample dielectric properties measurements using coaxial probes

    Energy Technology Data Exchange (ETDEWEB)

    Bringhurst, S.; Iskander, M.F.; White, M.J. [Univ. of Utah, Salt Lake City, UT (United States). Electrical Engineering Dept.

    1996-12-31

    A metallized ceramic probe has been designed for high temperature broadband dielectric properties measurements. The probe was fabricated out of an alumina tube and rod as the outer and inner conductors respectively. The alumina was metallized with a 3 mil layer of moly-manganese and then covered with a 0.5 mil protective layer of nickel plating. The probe has been used to make complex dielectric properties measurements over the complete frequency band from 500 MHz to 3 GHz, and for temperatures as high as 1,000 C. A 3D Finite-Difference Time-Domain (FDTD) code was used to help investigate the feasibility of this probe to measure the complex permittivity of thin samples. It is shown that by backing the material under test with a standard material of known dielectric constant, the complex permittivity of thin samples can be measured accurately using the developed FDTD algorithm. This FDTD procedure for making thin sample dielectric properties measurements will be described.

  9. Nano Materials

    International Nuclear Information System (INIS)

    Jin, In Ju; Lee, Ik Mo; Kwon, Yeung Gu

    2006-02-01

    This book introduces background of nano science such as summary, plenty room at the bottom, access way to nano technique, nanoparticles using bottom-up method which are a marvel of nature, and modern alchemy : chemical synthesis of artificial nano structure, understanding of quantum mechanics, STM/AFM, nano metal powder, ceramic nanoparticles, nano structure film, manufacture of nanoparticles using reverse micelle method, carbon nano tube, sol-gel material, nano energy material, nano catalyst nano bio material technology and spintronics.

  10. Nano-technology and nano-toxicology

    OpenAIRE

    Maynard, Robert L.

    2012-01-01

    Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of ...

  11. Fusion breeder sphere - PAC blanket design

    International Nuclear Information System (INIS)

    Sullivan, J.D.; Palmer, B.J.F.

    1987-11-01

    There is a considerable world-wide effort directed toward the production of materials for fusion reactors. Many ceramic fabrication groups are working on making lithium ceramics in a variety of forms, to be incorporated into the tritium breeding blanket which will surround the fusion reactor. Current blanket designs include ceramic in either monolithic or packed sphere bed (sphere-pac) forms. The major thrust at AECL is the production of lithium aluminate spheres to be incorporated in a sphere-pac bed. Contemporary studies on breeder blanket design offer little insight into the requirements on the sizes of the spheres. This study examined the parameters which determine the properties of pressure drop and coolant requirements. It was determined that an optimised sphere-pac bed would be composed of two diameters of spheres: 75 weight % at 3 mm and 25 weight % at 0.3 mm

  12. Formation of metal and dielectric liners using a solution process for deep trench capacitors.

    Science.gov (United States)

    Ham, Yong-Hyun; Kim, Dong-Pyo; Baek, Kyu-Ha; Park, Kun-Sik; Kim, Moonkeun; Kwon, Kwang-Ho; Shin, Hong-Sik; Lee, Kijun; Do, Lee-Mi

    2012-07-01

    We demonstrated the feasibility of metal and dielectric liners using a solution process for deep trench capacitor application. The deep Si trench via with size of 10.3 microm and depth of 71 microm were fabricated by Bosch process in deep reactive ion etch (DRIE) system. The aspect ratio was about 7. Then, nano-Ag ink and poly(4-vinylphenol) (PVPh) were used to form metal and dielectric liners, respectively. The thicknesses of the Ag and PVPh liners were about 144 and 830 nm, respectively. When the curing temperature of Ag film increased from 120 to 150 degrees C, the sheet resistance decreased rapidly from 2.47 to 0.72 Omega/sq and then slightly decreased to 0.6 Omega/sq with further increasing the curing temperature beyond 150 degrees C. The proposed liner formation method using solution process is a simple and cost effective process for the high capacity of deep trench capacitor.

  13. Mathematical Modeling of Electrical Conductivity of Dielectric with Dispersed Metallic Inclusions

    Directory of Open Access Journals (Sweden)

    V. S. Zarubin

    2015-01-01

    Full Text Available Composites are increasingly used for application in engineering as structural, thermal protection and functional materials, including dielectrics, because of a wide variety of properties. The relative dielectric constant and the dielectric loss tangent are basic functional characteristics of a composite used as a dielectric. The quantitative level of these characteristics is mainly affected by the properties of the composite matrix and inclusions as well as their shape and volume concentration. Metallic inclusions in a dielectric, which serves as a function of the composite matrix, expand electrical properties of the composite in particular increase its dielectric constant and dielectric loss tangent and thereby greatly expand its application field. Dielectric losses are defined by the imaginary component of the complex value of the relative dielectric constant of the dielectric. At a relatively low vibration frequency of electromagnetic field affecting the dielectric, this value is proportional to the electrical conductivity of the dielectric and inversely proportional to the frequency. In order to predict the expected value of the electric conductivity of the dielectric with metallic inclusions, a mathematical model that properly describes the structure of the composite and the electrical interaction of the matrix and inclusions is required.In the paper, a mathematical model of the electrical interaction of the representative element of the composite structure and a homogeneous isotropic medium with electrical conductivity, which is desired characteristics of the composite, is constructed. Globular shape of the metallic inclusions as an average statistical form of dispersed inclusions with a comparable size in all directions is adopted. The inclusion is covered with a globular layer of electrical insulation to avoid percolation with increasing volume concentration of inclusions. Outer globular layer of representative structure of composite

  14. Carbon nano tubes embedded in polymer nano fibers

    International Nuclear Information System (INIS)

    Dror, Y.; Kedem, S.; Khalfin, R.L.; Paz, Y.; Cohenl, Y.; Salalha, Y.; Yarin, A.L.; Zussman, A.

    2004-01-01

    Full Text: The electro spinning process was used successfully to embed Multi-walled carbon nano tubes (MWCNTs) and single-walled carbon nano tubes (SWCNTs) in a matrix of poly(ethylene oxide) (PEO) forming composite nano fibers. Initial dispersion of SWCNTs in water was achieved by the use of an amphphilic alternating copolymer of styrene and sodium maleate. MWNT dispersion was achieved by ionic and nonionic surfactants. The distribution and conformation of the nano tubes in the nano fibers were studied by transmission electron microscopy (TEM). Oxygen plasma etching was used to expose the nano tubes within the nano fibers to facilitate direct observation. Nano tube alignment within the nano fibers was shown to depend strongly on the quality of the initial dispersions. Well-dispersed and separated nano tubes were embedded in a straight and aligned form while entangled non-separated nano tubes were incorporated as dense aggregates. X-ray diffraction demonstrated a high degree of orientation of the PEO crystals in the electro spun nano fibers with embedded SWCNTs, whereas incorporation of MVCNTs had a detrimental effect on the polymer orientation. Composite polymer nano fibers containing dispersed phases of nanometric TiO 2 particles and MWCNTs were also prepared electro spinning. In this case, the polymer matrix was poly(acrylonitrile) (PAN). The morphology and possible applications of these composite nano fibers will be discussed

  15. Electromagnetic Pulse Generated by a Horizontal Electric Dipole over a Perfect Conductor Covered with a Dielectric Layer

    Directory of Open Access Journals (Sweden)

    Zheng Juan

    2018-01-01

    Full Text Available In this paper, the electromagnetic pulse due to a delta-function current excitation has been derived on the planar surface of a perfect conductor coated by a dielectric layer. The approximate expression of wave component is obtained when both the transmitting source and the receiving antennas are located on the surface of the dielectric. When the thickness of the intermediate layer is subjected to the condition of k1l<<0.6, this physical model is applied to the microstrip circuit. Analysis and computations of the wave components are carried out on the microstrip circuit, including the surface trapped wave vector which had been ignored in former studies. It is shown that the trapped-surface-wave terms should have been taken into consideration as the main contribution in total transient field in the far-field radiations.

  16. Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface fo...

  17. Tungsten nano-tendril growth in the Alcator C-Mod divertor

    International Nuclear Information System (INIS)

    Wright, G.M.; Brunner, D.; Labombard, B.; Lipschultz, B.; Terry, J.L.; Whyte, D.G.; Baldwin, M.J.; Doerner, R.P.

    2012-01-01

    Growth of tungsten nano-tendrils (‘fuzz’) has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The thickness of the individual nano-tendrils (50–100 nm) and the depth of the layer (600 ± 150 nm) are consistent with observations from experiments on linear plasma devices. The observation of tungsten fuzz in a tokamak may have important implications for material erosion, dust formation, divertor lifetime and tokamak operations in next-step devices. (letter)

  18. SPHERE: Irradiation of sphere-pac fuel of UPuO2−x containing 3% Americium

    International Nuclear Information System (INIS)

    D’Agata, E.; Hania, P.R.; McGinley, J.; Somers, J.; Sciolla, C.; Baas, P.J.; Kamer, S.; Okel, R.A.F.; Bobeldijk, I.; Delage, F.; Bejaoui, S.

    2014-01-01

    Highlights: • SPHERE is designed to check the behaviour of MADF sphere-pac concept. • MADF sphere-pac are compared with MADF pellet. • Swelling, helium release and restructuring behaviour will be the main output of the experiment. • An experiment to check sphere-pac MABB fuel behaviour is now under design. - Abstract: Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors of long-lived nuclides like 241 Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. The SPHERE irradiation experiment is the latest of a series of European experiments on americium transmutation (e.g. EFTTRA-T4, EFTTRA-T4bis, HELIOS, MARIOS) performed in the HFR (High Flux Reactor). The SPHERE experiment is carried out in the framework of the 4-year project FAIRFUELS of the EURATOM 7th Framework Programme (FP7). During the past years of experimental works in the field of transmutation and tests of innovative nuclear fuels, the release or trapping of helium as well as helium induced fuel swelling have been shown to be the key issues for the design of Am-bearing targets. The main objective of the SPHERE experiment is to study the in-pile behaviour of fuel containing 3% of americium and to compare the behaviour of sphere-pac fuel to pellet fuel, in particular the role of microstructure and temperature on fission gas release (mainly He) and on fuel swelling. The SPHERE experiment is being irradiated since September 2013 in the HFR in Petten (The Netherlands) and is expected to be terminated in spring 2015. The experiment has been designed to last up to 18 reactor cycles (corresponding to 18 months) but may reach its target earlier. This paper discusses the rationale and objective of the SPHERE experiment and provides a general description of its design

  19. Proceedings of the 1st CIRP Seminar on Micro and Nano Technology

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Alting, Leo

    2003-01-01

    The present Proceedings of the 1st International CIRP Seminar on Micro and Nano Technology is the result of a CIRP initiative taken by the Working Group on Micro/Nano Technology established in 2002. The CIRP initiative is a recognition of the large potentials that micro/nano technology has...... in improving/enhancing many of the existing products and in forming the basis of a long range of new next generation of products. Micro and nano technology are common phrases used to describe phenomena, components, products etc. related to small dimensions, usually based on functioning principles...... accessible to a large group of customers. Therefore, product development and manufacture is very essential. Therefore this 1st CIRP Seminar represents an important milestone for design and industrial manufacture of products based on micro and nano technology. The Proceedings cover mostly new, interesting...

  20. Simulation of induced electric field distribution based on five-sphere model used in rTMS.

    Science.gov (United States)

    Pu, Lina; Liu, Zhipeng; Yin, Tao; An, Hao; Li, Song

    2010-01-01

    Repetitive Transcranial magnetic stimulation (TMS) is a relatively new technique, which is non-invasive and painless used to stimulate the central and peripheral neural tissues. The principle is generating time-varying magnetic fields to stimulate the cerebral cortex neuron and inducing eddy current inside the tissues. Many researches study on the distributing of magnetic field and electric field induced inside the human brain, whereas the static electric field was neglected roughly in many studies. In this paper, a five-sphere model is established to simulate the human head used in rTMS. According to the different dielectric properties of the head tissues, the Laplace equation of static electric field is deduced by both of Gauss theorem and current's continuity principle. Boundary conditions used in different interface between two adjacent layers in the five-sphere model is proposed in this paper. Simulating study is conducted to calculate the distribution of the electric field in the model. Simulating results suggest that the model is useful to get the parameters of the most focus coil. Therefore this study could be potential to promote the development of rTMS stimulator.

  1. Magneto-thermal and dielectric properties of biferroic YCrO3 prepared by combustion synthesis

    International Nuclear Information System (INIS)

    Duran, A.; Arevalo-Lopez, A.M.; Castillo-Martinez, E.; Garcia-Guaderrama, M.; Moran, E.; Cruz, M.P.; Fernandez, F.; Alario-Franco, M.A.

    2010-01-01

    Microstructural, magnetothermal and dielectric properties of YCrO 3 powders prepared by combustion and solid state methods have been studied by a combination of XRD, specific heat, magnetization and permittivity measurements. The TEM and XRD characterization confirm that the combustion powders are amorphous plate-like agglomerates of nano-sized crystalline particles. A more uniform grain size along with an increase of the relative density is observed by SEM in the sintered samples prepared by combustion route with respect to those produced by solid state reaction. Similar to the material obtained through solid state synthesis, the material prepared by the combustion method also shows spin canted antiferromagnetic ordering of Cr +3 (S=3/2) at ∼140 K, which is shown by magnetization as well as λ-type anomaly in the total specific heat. Furthermore, the magnetic contribution to the total specific heat reveals spin fluctuations above T N and a spin reorientation transition at about 60 K. Both YCrO 3 compounds show a diffuse phase transition at about 450 K, typical of a relaxor ferroelectric, which is characterized by a broad peak in the real part of the dielectric permittivity as a function of temperature, with the peak decreasing in magnitude and shifting to higher temperature as the frequency increases. The relaxor dipoles are due to the local non-centrosymmetric structure. Furthermore, the high loss tangent in a broad range of temperature as well as conductivity analysis indicates a hopping mechanism for the electronic conductivity as we believe it is a consequence of the outer d 3 -shell, which have detrimental effects on the polarization and the pooling process in the YCrO 3 bulk material. The more uniform particle size and higher density material synthesized through the combustion process leads to an improvement in the dielectric Properties. - Graphical abstract: Combustion method: An alternative route for synthesized a new family of multiferroics. Amorphous

  2. Simulation of rotary-drum and repose tests for frictional spheres and rigid sphere clusters

    Energy Technology Data Exchange (ETDEWEB)

    Walton, O.R.; Braun, R.L.

    1993-11-01

    The effects of rotation rate and interparticle friction on the bulk flow behavior in rotating horizontal cylinders are studied via particle-dynamic simulations. Assemblies of inelastic, frictional spheres and rigid sphere clusters are utilized, and rotation rates from quasistatic to centrifuging are examined. Flow phenomena explored include size segregation, avalanching, slumping and centrifuging. Simulated drum flows with two sizes of frictional spheres showed very rapid segregation of species perpendicular to the drum axis; however, simulations of up to 10 revolutions, utilizing periodic-boundary ends, did not exhibit the experimentally observed axial segregation into stripes. Angles of repose for uniform-sized spheres in slowly rotating cylinders varied from 13 to 31 degrees as the friction coefficient varied from 0.02 to 1.0. For simulated rotation rates higher than the threshold to obtain uniform flow conditions, the apparent angle of repose increases as the rotation rats increases, consistent with experiments. Also, simulations with rigid clusters of 4 spheres in a tetrahedral shape or 8 spheres in a cubical arrangement, demonstrate that particle shape strongly influences the repose angle. Simulations of cubical 8-sphere clusters, with a surface coefficient of friction of 0.1, produced apparent angles of repose exceeding 35 degrees, compared to 23 degrees for assemblies of single spheres interacting with the same force model parameters. Centrifuging flows at very high rotation rates exist as stationary beds moving exactly as the outer rotating wall. At somewhat slower speeds the granular bed remains in contact with the wall but exhibits surface sliding down the rising inner bed surface, moving a short distance on each revolution. At still slower speeds particles rain from the surface of the upper half of the rotating bed.

  3. Effect of chromium substitution on the dielectric properties of mixed Ni-Zn ferrite prepared by WOWS sol–gel technique

    International Nuclear Information System (INIS)

    Ashtar, M.; Munir, A.; Anis-ur-Rehman, M.; Maqsood, A.

    2016-01-01

    Graphical abstract: Variation of AC conductivity (σ AC ) as a function of natural log of angular frequency (lnω) for Ni 0.5 Zn 0.5 Fe 2-x Cr x O 4 nanoferrites at room temperature. - Highlights: • Cr doped mixed Ni-Zn ferrites were successfully synthesized by a newly developed WOWS sol gel technique. • The specific surface area and specific surface area to volume ratio increased with decrease in particle size. • The resonance peaks appeared in dielectric loss graphs, shifting towards low frequency with the increase in Cr concentration. • The prepared samples have the lowest values of the dielectric constant. • The dielectric constant were observed to be inversely proportional to square root of the AC resistivity. - Abstract: Cr +3 doped Ni-Zn nanoferrite samples with composition Ni 0.5 Zn 0.5 Fe 2-x Cr x O 4 (x = 0.1, 0.2, 0.3, 0.4) were synthesized With Out Water and Surfactant (WOWS) sol-gel technique. The structural, morphological and dielectric properties of the samples were investigated. The lattice constant, crystallite size, theoretical density and porosity of each sample were obtained from X-ray diffraction (XRD) data. The specific surface area and specific surface area to volume ratio increased with the decrease in the size of Cr +3 doped Ni-Zn ferrite nanoparticles, as the concentration of Cr +3 increased. The SEM analysis revealed that the particles were of nano size and of spherical shape. The dielectric parameters such as dielectric constant (ε′) and dielectric loss (tanδ) of all the samples as a function of frequency at room temperature were measured. The AC conductivity (σ AC ) was determined from the dielectric parameters, which showed increasing trend with the rise in frequency.

  4. Microwave measurement and modeling of the dielectric properties of vegetation

    Science.gov (United States)

    Shrestha, Bijay Lal

    Some of the important applications of microwaves in the industrial, scientific and medical sectors include processing and treatment of various materials, and determining their physical properties. The dielectric properties of the materials of interest are paramount irrespective of the applications, hence, a wide range of materials covering food products, building materials, ores and fuels, and biological materials have been investigated for their dielectric properties. However, very few studies have been conducted towards the measurement of dielectric properties of green vegetations, including commercially important plant crops such as alfalfa. Because of its high nutritional value, there is a huge demand for this plant and its processed products in national and international markets, and an investigation into the possibility of applying microwaves to improve both the net yield and quality of the crop can be beneficial. Therefore, a dielectric measurement system based upon the probe reflection technique has been set up to measure dielectric properties of green plants over a frequency range from 300 MHz to 18 GHz, moisture contents from 12%, wet basis to 79%, wet basis, and temperatures from -15°C to 30°C. Dielectric properties of chopped alfalfa were measured with this system over frequency range of 300 MHz to 18 GHz, moisture content from 11.5%, wet basis, to 73%, wet basis, and density over the range from 139 kg m-3 to 716 kg m-3 at 23°C. The system accuracy was found to be +/-6% and +/-10% in measuring the dielectric constant and loss factor respectively. Empirical, semi empirical and theoretical models that require only moisture content and operating frequency were determined to represent the dielectric properties of both leaves and stems of alfalfa at 22°C. The empirical models fitted the measured dielectric data extremely well. The root mean square error (RMSE) and the coefficient of determination (r2) for dielectric constant and loss factor of leaves

  5. Boron nitride as two dimensional dielectric: Reliability and dielectric breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yanfeng; Pan, Chengbin; Hui, Fei; Shi, Yuanyuan; Lanza, Mario, E-mail: mlanza@suda.edu.cn [Institute of Functional Nano and Soft Materials, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123 (China); Zhang, Meiyun; Long, Shibing [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Lian, Xiaojuan; Miao, Feng [National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Larcher, Luca [DISMI, Università di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Wu, Ernest [IBM Research Division, Essex Junction, Vermont 05452 (United States)

    2016-01-04

    Boron Nitride (BN) is a two dimensional insulator with excellent chemical, thermal, mechanical, and optical properties, which make it especially attractive for logic device applications. Nevertheless, its insulating properties and reliability as a dielectric material have never been analyzed in-depth. Here, we present the first thorough characterization of BN as dielectric film using nanoscale and device level experiments complementing with theoretical study. Our results reveal that BN is extremely stable against voltage stress, and it does not show the reliability problems related to conventional dielectrics like HfO{sub 2}, such as charge trapping and detrapping, stress induced leakage current, and untimely dielectric breakdown. Moreover, we observe a unique layer-by-layer dielectric breakdown, both at the nanoscale and device level. These findings may be of interest for many materials scientists and could open a new pathway towards two dimensional logic device applications.

  6. The nano-micro interface bridging the micro and nano worlds

    CERN Document Server

    Werner, Matthias; Fecht, Hans-Jörg

    2015-01-01

    This second, enlarged edition has been fully updated to address the rapid progress made within this field in recent years. Internationally recognized experts provide comprehensive, first-hand information, resulting in an overview of the entire nano-micro world. In so doing, they cover aspects of funding and commercialization, the manufacture and future applications of nanomaterials, the fundamentals of nanostructures leading to macroscale objects as well as the ongoing miniaturization toward the nanoscale domain. Along the way, the authors explain the effects occurring at the nanoscale and the nanotechnological characterization techniques. An additional topic on the role of nanotechnology in energy and mobility covers the challenge of developing materials and devices, such as electrodes and membrane materials for fuel cells and catalysts for sustainable transportation. Also new to this edition are the latest figures for funding, investments, and commercialization prospects, as well as recent research programs...

  7. Filtering properties of Thue-Morse nano-photonic crystals containing high-temperature superconductor

    Science.gov (United States)

    Talebzadeh, Robabeh; Bavaghar, Mehrdad

    2018-05-01

    In this paper, we introduced new design of quasi-periodic layered structures by choosing order two of ternary Thue-Morse structure. We considered Superconductor-dielectric photonic crystal with mirror symmetric as (ABSSAB)N(BASSBA)N composed of two kinds of nano-scale dielectric layers (A and B) and high-temperature superconductor layers where N is the number of period. This structure is assumed to be the free space. By using the transfer matrix method and the two fluid model, we theoretically study the transmission spectrum of ternary Thue-Morse superconducting photonic crystals with mirror symmetry and introduce this structure as a narrow optical filter. We showed that transmission peak so-called defect mode appears itself inside the transmission spectrum of suggested structure as same as defective layered structure. Also, we analyzed the influence of various related parameters such as the operating temperature of superconductor layer on position of defect mode. The redshift of defect mode with increasing the operating temperature was observed.

  8. Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

    Science.gov (United States)

    Banerjee, Ananya; Sarkar, A.

    2016-05-01

    The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

  9. Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Ananya, E-mail: banerjee.ananya2008@gmail.com; Sarkar, A. [Dept. of Physics, Bijoy Krishna Girls’ College, 5/3 M.G. Road, Howrah 711101, W.B. (India)

    2016-05-06

    The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

  10. Tunable silver-shell dielectric core nano-beads array for thin-film solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Chou Chau, Yuan-Fong, E-mail: a0920146302@gmail.com, E-mail: chou.fong@ubd.edu.bn; Lim, Chee Ming [Universiti Brunei Darussalam, Centre for Advanced Material and Energy Sciences (Brunei) (Brunei Darussalam); Chiang, Chien-Ying [National Taipei University of Technology, Department of Electro-Optical Engineering (China); Voo, Nyuk Yoong; Muhammad Idris, Nur Syafi’ie; Chai, Siew Ung [Universiti Brunei Darussalam, Centre for Advanced Material and Energy Sciences (Brunei) (Brunei Darussalam)

    2016-04-15

    The absorbance spectra of thin-film solar cells (TFSCs) can be enhanced by constructing the tunable periodic Ag-shell nano-bead (PASNB) arrays in the active material. In this paper, we investigated a plasmonic thin-film solar cell (TFSC) which composed of the arrays of PASNB deposited onto a crystalline silicon layer. By performing three-dimensional finite element method, we demonstrate that near field coupling among the PASNB arrays results in SPR modes with enhanced absorbance and field intensity. The proposed structure can significantly enhance the plasmonic activity in a wide range of incident light and enlarge working wavelength of absorbance in the range of near-UV, visible and near-infrared. We show that the sensitivity of the PASNB arrays reveals a linear relationship with the thickness of Ag-shell nano-bead (ASNB) for both the anti-bonding and bonding modes in the absorbance spectra. The broadband of absorbance spectra could be expanded as a wide range by varying the thickness of ASNB while the particle size is kept constant. Simulation results suggest this alternative scheme to the design and improvements on plasmonic enhanced TFSCs can be extended to other nanophotonic applications.

  11. Lattices of dielectric resonators

    CERN Document Server

    Trubin, Alexander

    2016-01-01

    This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

  12. Modifying the Casimir force between indium tin oxide film and Au sphere

    Science.gov (United States)

    Banishev, A. A.; Chang, C.-C.; Castillo-Garza, R.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Mohideen, U.

    2012-01-01

    We present complete results of the experiment on measuring the Casimir force between an Au-coated sphere and an untreated or, alternatively, UV-treated indium tin oxide (ITO) film deposited on a quartz substrate. Measurements were performed using an atomic force microscope in a high vacuum chamber. The measurement system was calibrated electrostatically. Special analysis of the systematic deviations is performed, and respective corrections in the calibration parameters are introduced. The corrected parameters are free from anomalies discussed in the literature. The experimental data for the Casimir force from two measurement sets for both untreated and UV-treated samples are presented. The random, systematic, and total experimental errors are determined at a 95% confidence level. It is demonstrated that the UV treatment of an ITO plate results in a significant decrease in the magnitude of the Casimir force (from 21% to 35% depending on separation). However, ellipsometry measurements of the imaginary parts of dielectric permittivities of the untreated and UV-treated samples did not reveal any significant differences. The experimental data are compared with computations in the framework of the Lifshitz theory. It is found that the data for the untreated sample are in a very good agreement with theoretical results taking into account the free charge carriers in an ITO film. For the UV-treated sample the data exclude the theoretical results obtained with account of free charge carriers. These data are in very good agreement with computations disregarding the contribution of free carriers in the dielectric permittivity. According to the hypothetical explanation provided, this is caused by the phase transition of the ITO film from metallic to dielectric state caused by the UV treatment. Possible applications of the discovered phenomenon in nanotechnology are discussed.

  13. Two-phase mixed media dielectric with macro dielectric beads for enhancing resistivity and breakdown strength

    Science.gov (United States)

    Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary

    2014-06-10

    A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

  14. Higher-dimensional relativistic-fluid spheres

    International Nuclear Information System (INIS)

    Patel, L. K.; Ahmedabad, Gujarat Univ.

    1997-01-01

    They consider the hydrostatic equilibrium of relativistic-fluid spheres for a D-dimensional space-time. Three physically viable interior solutions of the Einstein field equations corresponding to perfect-fluid spheres in a D-dimensional space-time are obtained. When D = 4 they reduce to the Tolman IV solution, the Mehra solution and the Finch-Skea solution. The solutions are smoothly matched with the D-dimensional Schwarzschild exterior solution at the boundary r = a of the fluid sphere. Some physical features and other related details of the solutions are briefly discussed. A brief description of two other new solutions for higher-dimensional perfect-fluid spheres is also given

  15. A new nanocomposite polymer electrolyte based on poly(vinyl alcohol) incorporating hypergrafted nano-silica

    KAUST Repository

    Hu, Xian-Lei

    2012-01-01

    Solid-state nanocomposite polymer electrolytes based on poly(vinyl alcohol)(PVA) incorporating hyperbranched poly(amine-ester) (HBPAE) grafted nano-silica (denoted as SiO2-g-HBPAE) have been prepared and investigated. Through surface pretreatment of nanoparticles, followed by Michael-addition and a self-condensation process, hyperbranched poly(amine-ester) was directly polymerized from the surface of nano-silica. Then the hypergrafted nanoparticles were added to PVA matrix, and blended with lithium perchlorate via mold casting method to fabricate nanocomposite polymer electrolytes. By introducing hypergrafted nanoparticles, ionic conductivity of solid composite is improved significantly at the testing temperature. Hypergrafted nano-silica may act as solid plasticizer, promoting lithium salt dissociation in the matrix as well as improving segmental motion of matrix. In addition, tensile testing shows that such materials are soft and tough even at room temperature. From the dielectric spectra of nanocomposite polymer electrolyte as the function of temperature, it can be deduced that Arrhenius behavior appears depending on the content of hypergrafted nano-silica and concentration of lithium perchlorate. At a loading of 15 wt% hypergrafted nano-silica and 54 wt% lithium perchlorate, promising ionic conductivities of PVA nanocomposite polymer electrolyte are achieved, about 1.51 × 10 -4 S cm-1 at 25 °C and 1.36 × 10-3 S cm-1 at 100 °C. © The Royal Society of Chemistry.

  16. Characterization of dielectric materials

    Energy Technology Data Exchange (ETDEWEB)

    King, Danny J.; Babinec, Susan; Hagans, Patrick L.; Maxey, Lonnie C.; Payzant, Edward A.; Daniel, Claus; Sabau, Adrian S.; Dinwiddie, Ralph B.; Armstrong, Beth L.; Howe, Jane Y.; Wood, III, David L.; Nembhard, Nicole S.

    2017-06-27

    A system and a method for characterizing a dielectric material are provided. The system and method generally include applying an excitation signal to electrodes on opposing sides of the dielectric material to evaluate a property of the dielectric material. The method can further include measuring the capacitive impedance across the dielectric material, and determining a variation in the capacitive impedance with respect to either or both of a time domain and a frequency domain. The measured property can include pore size and surface imperfections. The method can still further include modifying a processing parameter as the dielectric material is formed in response to the detected variations in the capacitive impedance, which can correspond to a non-uniformity in the dielectric material.

  17. Improved dielectric properties, mechanical properties, and thermal conductivity properties of polymer composites via controlling interfacial compatibility with bio-inspired method

    Science.gov (United States)

    Ruan, Mengnan; Yang, Dan; Guo, Wenli; Zhang, Liqun; Li, Shuxin; Shang, Yuwei; Wu, Yibo; Zhang, Min; Wang, Hao

    2018-05-01

    Surface functionalization of Al2O3 nano-particles by mussel-inspired poly(dopamine) (PDA) was developed to improve the dielectric properties, mechanical properties, and thermal conductivity properties of nitrile rubber (NBR) matrix. As strong adhesion of PDA to Al2O3 nano-particles and hydrogen bonds formed by the catechol groups of PDA and the polar acrylonitrile groups of NBR, the dispersion of Al2O3-PDA/NBR composites was improved and the interfacial force between Al2O3-PDA and NBR matrix was enhanced. Thus, the Al2O3-PDA/NBR composites exhibited higher dielectric constant, better mechanical properties, and larger thermal conductivity comparing with Al2O3/NBR composites at the same filler content. The largest thermal conductivity of Al2O3-PDA/NBR composite filled with 30 phr Al2O3-PDA was 0.21 W/m K, which was 122% times of pure NBR. In addition, the Al2O3-PDA/NBR composite filled with 30 phr Al2O3-PDA displayed a high tensile strength about 2.61 MPa, which was about 255% of pure NBR. This procedure is eco-friendly and easy handling, which provides a promising route to polymer composites in application of thermal conductivity field.

  18. Insight into the electrical properties and chain conformation of spherical polyelectrolyte brushes by dielectric spectroscopy

    Science.gov (United States)

    Guo, Xiaoxia; Zhao, Kongshuang

    2017-02-01

    We report here a dielectric study on three kinds of anionic spherical polyelectrolyte brush (SPBs, consisting of a polystyrene (PS) core and three different poly (acrylic acid) chains grafted onto the core) suspensions over a frequency ranging from 40 Hz to 110 MHz. The relaxation behavior of the SPB suspensions shows significant changes in the brush-layer properties when the mass fraction of SPBs and the pH of the suspensions change. Two definite relaxations related to the interfacial polarization are observed around 100 kHz and 10 MHz. A single-layer spherical-shell model is applied to describe the SPB suspensions wherein the suspended SPB is modeled as a spherical-shell composite particle in which an insulated PS sphere is surrounded by a conducting ion-permeable shell (the polyelectrolyte chain layer). We developed the curve-fitting procedure to analyze the dielectric spectrum in order to obtain the dielectric properties of the components of the SPBs, especially the properties of the polyelectrolyte brush. Based on this method and model, the permittivity and conductivity of the brush layer, ζ potential, etc are calculated. The ordered orientation of the water molecules in the layer leads to an additional electrical dipole moment; increasing pH causes the brush layer to swell. In addition, the repulsive force between the SPB particles are evaluated using the brush-layer thickness, which is obtained by fitting dielectric spectra, combined with relative theoretical formulas. Increasing PH values or SPB concentration would improve the stability of the SPBs dispersion.

  19. Si quantum dots for nano electronics: From materials to applications

    International Nuclear Information System (INIS)

    Lombardo, S.; Spinella, C.; Rimini, E.

    2005-01-01

    This paper reviews the subject of Si quantum dots embedded in dielectric and its application to the realization of non volatile semiconductor memories. In the first part of the paper various approaches for the analysis of the materials through transmission electron microscopy (TEM) are critically discussed. The advantages coming from an innovative application of energy filtered TEM are put in clear evidence. The paper then focuses on the synthesis of the materials: two different methodologies for the realization of the dots, both based on chemical vapor deposition are described in detail, and physical models providing some understanding of the observed phenomenology are reported. We then discuss the application of this nano technology to the realization of the storage nodes in non volatile semiconductor memories. The following sections describe the electrical characteristics found in the test devices and some key aspects are described in terms of quantitative models. The test devices show several performance advantages, indicating that the approach is an excellent candidate for the realization of Flash memories of the nano electronic era

  20. Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures

    Science.gov (United States)

    2018-02-19

    AFRL-AFOSR-JP-TR-2018-0012 Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures PHILIP Kim HARVARD COLLEGE PRESIDENT...21-02-2018 2.  REPORT TYPE      Final 3.  DATES COVERED (From - To)      15 Aug 2015 to 14 Feb 2017 4.  TITLE AND SUBTITLE Nano Electronics on...NOTES 14.  ABSTRACT We report molecular beam epitaxial growth and electronic transport properties of high quality topological insulator Bi2Se3 thin films

  1. Nano Sensing and Energy Conversion Using Surface Plasmon Resonance (SPR

    Directory of Open Access Journals (Sweden)

    Iltai (Isaac Kim

    2015-07-01

    Full Text Available Nanophotonic technique has been attracting much attention in applications of nano-bio-chemical sensing and energy conversion of solar energy harvesting and enhanced energy transfer. One approach for nano-bio-chemical sensing is surface plasmon resonance (SPR imaging, which can detect the material properties, such as density, ion concentration, temperature, and effective refractive index in high sensitivity, label-free, and real-time under ambient conditions. Recent study shows that SPR can successfully detect the concentration variation of nanofluids during evaporation-induced self-assembly process. Spoof surface plasmon resonance based on multilayer metallo-dielectric hyperbolic metamaterials demonstrate SPR dispersion control, which can be combined with SPR imaging, to characterize high refractive index materials because of its exotic optical properties. Furthermore, nano-biophotonics could enable innovative energy conversion such as the increase of absorption and emission efficiency and the perfect absorption. Localized SPR using metal nanoparticles show highly enhanced absorption in solar energy harvesting. Three-dimensional hyperbolic metamaterial cavity nanostructure shows enhanced spontaneous emission. Recently ultrathin film perfect absorber is demonstrated with the film thickness is as low as ~1/50th of the operating wavelength using epsilon-near-zero (ENZ phenomena at the wavelength close to SPR. It is expected to provide a breakthrough in sensing and energy conversion applications using the exotic optical properties based on the nanophotonic technique.

  2. Imaging optical fields below metal films and metal-dielectric waveguides by a scanning microscope

    Science.gov (United States)

    Zhu, Liangfu; Wang, Yong; Zhang, Douguo; Wang, Ruxue; Qiu, Dong; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Rosenfeld, Mary; Lakowicz, Joseph R.

    2017-09-01

    Laser scanning confocal fluorescence microscopy (LSCM) is now an important method for tissue and cell imaging when the samples are located on the surfaces of glass slides. In the past decade, there has been extensive development of nano-optical structures that display unique effects on incident and transmitted light, which will be used with novel configurations for medical and consumer products. For these applications, it is necessary to characterize the light distribution within short distances from the structures for efficient detection and elimination of bulky optical components. These devices will minimize or possibly eliminate the need for free-space light propagation outside of the device itself. We describe the use of the scanning function of a LSCM to obtain 3D images of the light intensities below the surface of nano-optical structures. More specifically, we image the spatial distributions inside the substrate of fluorescence emission coupled to waveguide modes after it leaks through thin metal films or dielectric-coated metal films. The observed spatial distribution were in general agreement with far-field calculations, but the scanning images also revealed light intensities at angles not observed with classical back focal plane imaging. Knowledge of the subsurface optical intensities will be crucial in the combination of nano-optical structures with rapidly evolving imaging detectors.

  3. A simple method for reducing inevitable dielectric loss in high-permittivity dielectric elastomers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Mazurek, Piotr Stanislaw

    2016-01-01

    elastomer matrix, with high dielectric permittivity and a low Young's modulus, aligned with no loss of mechanical stability, was prepared through the use of commercially available chloropropyl-functional silicone oil mixed into a tough commercial liquid silicone rubber silicone elastomer. The addition...... also decreased the dielectric losses of an elastomer containing dielectric permittivity-enhancing TiO2 fillers. Commercially available chloropropyl-functional silicone oil thus constitutes a facile method for improved silicone DEs, with very low dielectric losses.......Commercial viability of dielectric elastomers (DEs) is currently limited by a few obstacles, including high driving voltages (in the kV range). Driving voltage can be lowered by either decreasing the Young's modulus or increasing the dielectric permittivity of silicone elastomers, or a combination...

  4. A Powerful Public Sphere?

    DEFF Research Database (Denmark)

    Fiig, Christina

    The paper holds a critical discussion of the Habermasian model of the public sphere and proposes a revised model of a general public......The paper holds a critical discussion of the Habermasian model of the public sphere and proposes a revised model of a general public...

  5. Dielectrics in electric fields

    CERN Document Server

    Raju, Gorur G

    2003-01-01

    Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

  6. Microwave properties of sphere-, flake-, and disc-shaped BaFe{sub 12}O{sub 19} nanoparticle inks for high-frequency applications on printed electronics

    Energy Technology Data Exchange (ETDEWEB)

    Myllymäki, S. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland); Maček Kržmanc, M. [Josef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Sloma, M. [Institute of Electronic Materials Technology (ITME) Department of Silicon Technology, 133 Wolczynska Street, 01-919 Warsaw (Poland); Juuti, J.; Nelo, M.; Teirikangas, M. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland); Jakubowska, M. [Institute of Electronic Materials Technology (ITME) Department of Silicon Technology, 133 Wolczynska Street, 01-919 Warsaw (Poland); Suvorov, D. [Josef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Jantunen, H. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland)

    2016-12-01

    Spherical (diameter 50–200 nm), flake- (diameter 40–200 nm), and disc-shaped (diameter 10–20 nm) BaFe{sub 12}O{sub 19} nanoparticles were synthesized with a wet chemical method, and their permittivity, electric loss tangent, permeability, and magnetic loss tangent were measured in the 0.045–10 GHz range. The materials were prepared using a solution of 12% PMMA resin in a butyldiglycol solvent for 10–50 wt% filling content. Microstrip transmission-line perturbation was used to measure complex permeability and the split post dielectric resonator method was employed to measure dielectric properties. The frequency dependence of the permeability and permittivity spectra of the composites was affected by their shape and filling fraction. The composites made with spherical particles had higher permeability values (1.4–1.75) at 1 GHz than the composites made with flake (1.25–1.6) or disc particles (1.1–1.3), but the spherical particles caused more losses. The flake particle composite provided permeability and magnetic loss characteristics at both 1 GHz and 7 GHz superior to those of the sphere particle composite in low-loss RF applications. The magnetic loss tangent of PMMA/BaFe{sub 12}O{sub 19} was 0.2–0.3 at 1 GHz, being lower than that of state-of-the-art PANI/BaFe{sub 12}O{sub 19} composites. The sphere composite inks showed permeability values less than 1 at 1–4 GHz ferromagnetic resonance (FMR); they could be used as a tunable material in microwave applications. The sphere and flake composite inks also had sufficient printing quality for the screen-printing fabrication method.

  7. PREFACE: Dielectrics 2009: Measurement Analysis and Applications

    Science.gov (United States)

    Vaughan, Alun; Williams, Graham

    2009-07-01

    College, Dublin. The Meeting discussed dielectric relaxation behaviour arising from molecular motions of dipolar molecules in the liquid and elastomeric states (now known as soft condensed matter) with measurements spanning a frequency range from a few Hz, through power and radiofrequencies, UHF and VHF, the microwave range and into the far infra-red. As a result of its success, it was decided at the Meeting that a continuing Dielectrics Discussion Group would be established to meet not more frequently than once a year. It was appreciated at the time that the subject of 'Dielectrics' covered many sub-areas, broadly classified into those of polarization, relaxation, conduction and high-field phenomena. For the DDG, a solution was to run annual meetings on chosen themes in dielectrics research, where the theme would change from one meeting to the next. Topics addressed in the early years of the DDG included high field phenomena and impurity effects, heterogeneous systems and biomaterials, polarization and conduction and non-linear dielectrics and ferroelectrics. The number of participants at these early meetings grew from 50 to the low 100's, which reflected both the increased awareness of the Group and increased participation from researchers in Continental Europe. However, the majority of participants in this period were from the UK, which reflected the considerable activities in dielectrics research in University, Industry and Government laboratories in the UK. There followed a series of DDG Meetings until 1974, at which point, the DDG became a registered charity: The Dielectrics Society. Many of the earlier meetings were held in the attractive and convenient venues of Oxford and Cambridge colleges but, in the early 1990's, a new venue for the meetings was established at the University of Kent at Canterbury. In 2001, the next major change occurred when The Dielectrics Society was incorporated into the Institute of Physics, becoming their Dielectrics Group. From 1968 to

  8. Analysis of specular resonance in dielectric bispheres using rigorous and geometrical-optics theories.

    Science.gov (United States)

    Miyazaki, Hideki T; Miyazaki, Hiroshi; Miyano, Kenjiro

    2003-09-01

    We have recently identified the resonant scattering from dielectric bispheres in the specular direction, which has long been known as the specular resonance, to be a type of rainbow (a caustic) and a general phenomenon for bispheres. We discuss the details of the specular resonance on the basis of systematic calculations. In addition to the rigorous theory, which precisely describes the scattering even in the resonance regime, the ray-tracing method, which gives the scattering in the geometrical-optics limit, is used. Specular resonance is explicitly defined as strong scattering in the direction of the specular reflection from the symmetrical axis of the bisphere whose intensity exceeds that of the scattering from noninteracting bispheres. Then the range of parameters for computing a particular specular resonance is specified. This resonance becomes prominent in a wide range of refractive indices (from 1.2 to 2.2) in a wide range of size parameters (from five to infinity) and for an arbitrarily polarized light incident within an angle of 40 degrees to the symmetrical axis. This particular scattering can stay evident even when the spheres are not in contact or the sizes of the spheres are different. Thus specular resonance is a common and robust phenomenon in dielectric bispheres. Furthermore, we demonstrate that various characteristic features in the scattering from bispheres can be explained successfully by using intuitive and simple representations. Most of the significant scatterings other than the specular resonance are also understandable as caustics in geometrical-optics theory. The specular resonance becomes striking at the smallest size parameter among these caustics because its optical trajectory is composed of only the refractions at the surfaces and has an exceptionally large intensity. However, some characteristics are not accounted for by geometrical optics. In particular, the oscillatory behaviors of their scattering intensity are well described by

  9. Study of surface plasmon resonance of core-shell nanogeometry under the influence of perovskite dielectric environment: Electrostatic approximation

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Nilesh Kumar; Sharma, R. P. [Centre for Energy Studies, Indian Institute of Technology, Delhi-110016 (India)

    2016-05-23

    We have systematically study the nano-plasmonic coupling to the perovskite (CH{sub 3}NH{sub 3}PbI{sub 3}) dielectric media in terms of surface plasmon resonance. The surface plasmon resonances are exhibited by the metal nanoparticles which is the electromagnetic excitation conduction electron when it is irradiated by incident light photon. Tunable behaviour of SPRs can be utilized to enhance the absorption of photon inside the surrounding environment in the wavelength range 300 to 800 nm. We have been selected two different types of nanogeometry such as coated and non-coated metal nanoparticles (radii ranges from 10 to 15 nm) to understand the plasmonic interaction to the dielectric media. Finally, we have observed that the coated nanogeometry is more preferable as compared to non-coated system to analyse the tunability of SPR peaks.

  10. Inductive dielectric analyzer

    International Nuclear Information System (INIS)

    Agranovich, Daniel; Popov, Ivan; Ben Ishai, Paul; Feldman, Yuri; Polygalov, Eugene

    2017-01-01

    One of the approaches to bypass the problem of electrode polarization in dielectric measurements is the free electrode method. The advantage of this technique is that, the probing electric field in the material is not supplied by contact electrodes, but rather by electromagnetic induction. We have designed an inductive dielectric analyzer based on a sensor comprising two concentric toroidal coils. In this work, we present an analytic derivation of the relationship between the impedance measured by the sensor and the complex dielectric permittivity of the sample. The obtained relationship was successfully employed to measure the dielectric permittivity and conductivity of various alcohols and aqueous salt solutions. (paper)

  11. Design and Development of Embedded Based System for the Measurement of Dielectric Constant Spectroscopy for Liquids

    Directory of Open Access Journals (Sweden)

    V. V. Ramana C. H.

    2010-09-01

    Full Text Available An embedded based system for the measurement of dielectric constant spectroscopy (for frequencies 1 kHz, 10 kHz, 100 kHz, 1 MHz and 10 MHz for liquids has been designed and developed. It is based on the principle that the change in frequency of an MAX 038 function generator, when the liquid forms the dielectric medium of the dielectric cell, is measured with a microcontroller. Atmel’s AT89LP6440 microcontroller is used in the present study. Further, an LCD module is interfaced with the microcontroller in 4-bit mode, which reduces the hardware complexity. Software is developed in C using Keil’s C-cross compiler. The instrument system covers a wide range of dielectric constants for various liquids at various frequencies and at different temperatures. The system is quite successful in the measurement of dielectric constant in liquids with an accuracy of ± 0.01 %. The dielectric constant is very dependent on the frequency of their measurement. No one-measurement technique is available, however, that will give the frequency range needed to characterize the liquid sample. The paper deals with the hardware and software details.

  12. Dielectric nanoresonators for light manipulation

    Science.gov (United States)

    Yang, Zhong-Jian; Jiang, Ruibin; Zhuo, Xiaolu; Xie, Ya-Ming; Wang, Jianfang; Lin, Hai-Qing

    2017-07-01

    Nanostructures made of dielectric materials with high or moderate refractive indexes can support strong electric and magnetic resonances in the optical region. They can therefore function as nanoresonators. In addition to plasmonic metal nanostructures that have been widely investigated, dielectric nanoresonators provide a new type of building blocks for realizing powerful and versatile nanoscale light manipulation. In contrast to plasmonic metal nanostructures, nanoresonators made of appropriate dielectric materials are low-cost, earth-abundant and have very small or even negligible light energy losses. As a result, they will find potential applications in a number of photonic devices, especially those that require low energy losses. In this review, we describe the recent progress on the experimental and theoretical studies of dielectric nanoresonators. We start from the basic theory of the electromagnetic responses of dielectric nanoresonators and their fabrication methods. The optical properties of individual dielectric nanoresonators are then elaborated, followed by the coupling behaviors between dielectric nanoresonators, between dielectric nanoresonators and substrates, and between dielectric nanoresonators and plasmonic metal nanostructures. The applications of dielectric nanoresonators are further described. Finally, the challenges and opportunities in this field are discussed.

  13. A recursive transfer-matrix solution for a dipole radiating inside and outside a stratified sphere

    International Nuclear Information System (INIS)

    Moroz, Alexander

    2005-01-01

    Fast and numerically stable transfer-matrix solution is presented for the classical electromagnetics problem of a dipole radiating inside and outside a stratified sphere consisting of concentric spherical shells. There is no limitation on the dipole position, the number of the concentric shells, the shell medium, or on the sphere radius. Electromagnetic fields are determined anywhere in the space, the time-averaged angular distribution of the radiated power, the total radiated power, Ohmic losses due to an absorbing shell, and Green's function are calculated. An absorbing, optically active, and ultrathin (-bar 10nm) metallic shell (core), characterized by a nonlocal dielectric function, are all allowed. The classical results are then applied to inelastic light scattering (fluorescence and Raman), the radiative and nonradiative normalized decay rates, and frequency shift. Using correspondence principle, the radiative decay rate is calculated from the Poynting vector, whereas the nonradiative decay rate is calculated from the Ohmic losses inside a sphere absorptive shell. Numerical stability of our method and limitations of classical description of decay rates are addressed. The importance of grouping various radiative and nonradiative decay mechanisms into local and nonlocal decay rates is emphasized. Further possible extensions of the theory presented here to the case of an arbitrary multilayered (axially symmetric) particle and to the classical problem of a radiating quadrupole in the presence of a multilayered particle are briefly outlined. Various applications for chemical speciation, LIDAR, fluorescent microscopy, engineering of decay rates, identification of biological particles, and monitoring specific cell functions are envisaged. Computer program is freely available at http://www.wave-scattering.com

  14. Light scattering of a Bessel beam by a nucleated biological cell: An eccentric sphere model

    Science.gov (United States)

    Wang, Jia Jie; Han, Yi Ping; Chang, Jiao Yong; Chen, Zhu Yang

    2018-02-01

    Within the framework of generalized Lorenz-Mie theory (GLMT), an eccentrically stratified dielectric sphere model illuminated by an arbitrarily incident Bessel beam is applied to investigate the scattering characteristics of a single nucleated biological cell. The Bessel beam propagating in an arbitrary direction is expanded in terms of vector spherical wave functions (VSWFs), where the beam shape coefficients (BSCs) are calculated rigorously in a closed analytical form. The effects of the half-cone angle of Bessel beam, the location of the particle in the beam, the size ratio of nucleus to cell, and the location of the nucleus inside the cell on the scattering properties of a nucleated cell are analyzed. The results provide useful references for optical diagnostic and imaging of particle having nucleated structure.

  15. Radiation Characteristics Enhancement of Dielectric Resonator Antenna Using Solid/Discrete Dielectric Lenses

    Directory of Open Access Journals (Sweden)

    H. A. E. Malhat

    2015-02-01

    Full Text Available The radiation characteristics of the dielectric resonator antennas (DRA is enhanced using different types of solid and discrete dielectric lenses. One of these approaches is by loading the DRA with planar superstrate, spherical lens, or by discrete lens (transmitarray. The dimensions and dielectric constant of each lens are optimized to maximize the gain of the DRA. A comparison between the radiations characteristics of the DRA loaded with different lenses are introduced. The design of the dielectric transmitarray depends on optimizing the heights of the dielectric material of the unit cell. The optimized transmitarray achieves 7 dBi extra gain over the single DRA with preserving the circular polarization. The proposed antenna is suitable for various applications that need high gain and focused antenna beam.

  16. Applications and research on nano power electronics: an adventure beyond quantum electronics

    Science.gov (United States)

    Chakraborty, Arindam; Emadi, Ali

    2005-06-01

    This paper is a roadmap to the exhaustive role of the newly emerging field of nanotechnology in various application and research areas. Some of the today's important topics are plasma, dielectric layer semiconductor, and carbon nanoparticle based technologies. Carbon nanotubes are very useful for the purpose of fabricating nano opto power devices. The basic concept behind tunneling of electrons has been utilized to define another scope of this technology, and thus came many quantum scale tunneling devices and elements. Fabrication of crystal semiconductors of high quality along with oxides of nano aspect would give rise to superior device performance and find applications such as LEDs, LASER, VLSI technology and also in highly efficient solar cells. Many nano-research based organizations are fully devoted to develop nano power cells, which would give birth to new battery cells, tunneling devises, with high power quality, longer lives, and higher activation rates. Different electronics industries as well as the military organizations would be largely benefited due to this major component and system design ideas of 'Smart Power' technologies. The contribution of nano scale power electronics would be realized in various fields like switching devices, electromechanical systems and quantum science. Such a sophisticated technology will have great impact on the modernization of robotics; space systems, automotive systems and many other fields. The highly emerging field of nanomedicine according to specialists would bring a dramatic revolution in the present century. However nanomedicine is nothing but an integration of biology, medicine and technology. Thermoelectric materials as been referred earlier also are used in case of implantable medical equipments for generation of electric power sufficient for those equipments.

  17. Inertial polarization of dielectrics

    OpenAIRE

    Zavodovsky, A. G.

    2011-01-01

    It was proved that accelerated motion of a linear dielectric causes its polarization. Accelerated translational motion of a dielectric's plate leads to the positive charge of the surface facing the direction of motion. Metal plates of a capacitor were used to register polarized charges on a dielectric's surface. Potential difference between the capacitor plates is proportional to acceleration, when acceleration is constant potential difference grows with the increase of a dielectric's area, o...

  18. Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications.

    Science.gov (United States)

    Nasir, Jamal; Jamaluddin, Mohd Haizal; Ahmad Khan, Aftab; Kamarudin, Muhammad Ramlee; Yen, Bruce Leow Chee; Owais, Owais

    2017-01-13

    An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE 111 and higher order TE 121 modes of the DRA. TE 111 degenerate mode covers LTE band 2 (1.85-1.99 GHz), 3 (1.71-1.88 GHz), and 9 (1.7499-1.7849 GHz) at f r = 1.8 GHz whereas TE 121 covers LTE band 7 (2.5-2.69 GHz) at f r = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work.

  19. High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    F. H. Wee

    2012-01-01

    Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

  20. Preparation of micro/nanostructure TiO2 spheres by controlling pollen as hard template and soft template.

    Science.gov (United States)

    Yang, Xiaohui; Xu, Bin; Zhang, Xuehong; Song, Xiuqin; Chen, Rufen

    2014-09-01

    In this paper, micro/nanostructure TiO2 spheres were synthesized by a sunflower pollen induced and self-assembly mineralization process, in which a titania precursor and pollen reacted in one-pot at normal pressure. In this paper, the bio-template advantage, as hard and soft template is fully demonstrated. The superiority of our synthesis is that we not only can control pollen as hard template, but also can control it as soft template only by changing reactions temperature. Under 80 degrees C of water bath, TiO2 microspheres which replicated the morphology of pollen were prepared by controlling pollen as hard template. Under 100 degrees C, hierarchical TiO2 spheres with complicated morphology, different from pollen template, were synthesized by using pollen as soft template. At the same time, judicious choice of the amount of pollen affords the synthesis of hierarchical structures spheres with adjustable morphology and crystal structure. The morphology can be tuned from microspheres constructed from TiO2 nanorods to nanospheres constructed from TiO2 nanoparticles, and the crystal structure can be tuned from rutile to anatase. More over this anatase phase can be keep better even at high temperature of 1000 degrees C. The as-prepared micro/nano structure photocatalysts not only have high photocatalytic activities, but also have good separability and reuse performance.

  1. Dielectric materials for electrical engineering

    CERN Document Server

    Martinez-Vega, Juan

    2013-01-01

    Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

  2. Cast dielectric composite linear accelerator

    Science.gov (United States)

    Sanders, David M [Livermore, CA; Sampayan, Stephen [Manteca, CA; Slenes, Kirk [Albuquerque, NM; Stoller, H M [Albuquerque, NM

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  3. Stress measurements of planar dielectric elastomer actuators

    Energy Technology Data Exchange (ETDEWEB)

    Osmani, Bekim; Aeby, Elise A.; Müller, Bert [Biomaterials Science Center, University of Basel, Gewerbestrasse 14, 4123 Allschwil (Switzerland)

    2016-05-15

    Dielectric elastomer actuator (DEA) micro- and nano-structures are referred to artificial muscles because of their specific continuous power and adequate time response. The bending measurement of an asymmetric, planar DEA is described. The asymmetric cantilevers consist of 1 or 5 μm-thin DEAs deposited on polyethylene naphthalate (PEN) substrates 16, 25, 38, or 50 μm thick. The application of a voltage to the DEA electrodes generates an electrostatic pressure in the sandwiched silicone elastomer layer, which causes the underlying PEN substrate to bend. Optical beam deflection enables the detection of the bending angle vs. applied voltage. Bending radii as large as 850 m were reproducibly detected. DEA tests with electric fields of up to 80 V/μm showed limitations in electrode’s conductivity and structure failures. The actuation measurement is essential for the quantitative characterization of nanometer-thin, low-voltage, single- and multi-layer DEAs, as foreseen for artificial sphincters to efficiently treat severe urinary and fecal incontinence.

  4. Stress measurements of planar dielectric elastomer actuators

    International Nuclear Information System (INIS)

    Osmani, Bekim; Aeby, Elise A.; Müller, Bert

    2016-01-01

    Dielectric elastomer actuator (DEA) micro- and nano-structures are referred to artificial muscles because of their specific continuous power and adequate time response. The bending measurement of an asymmetric, planar DEA is described. The asymmetric cantilevers consist of 1 or 5 μm-thin DEAs deposited on polyethylene naphthalate (PEN) substrates 16, 25, 38, or 50 μm thick. The application of a voltage to the DEA electrodes generates an electrostatic pressure in the sandwiched silicone elastomer layer, which causes the underlying PEN substrate to bend. Optical beam deflection enables the detection of the bending angle vs. applied voltage. Bending radii as large as 850 m were reproducibly detected. DEA tests with electric fields of up to 80 V/μm showed limitations in electrode’s conductivity and structure failures. The actuation measurement is essential for the quantitative characterization of nanometer-thin, low-voltage, single- and multi-layer DEAs, as foreseen for artificial sphincters to efficiently treat severe urinary and fecal incontinence.

  5. Further Investigations of NIST Water Sphere Discrepancies

    International Nuclear Information System (INIS)

    Broadhead, B.L.

    2001-01-01

    Measurements have been performed on a family of water spheres at the National Institute of Standards and Technology (NIST) facilities. These measurements are important for criticality safety studies in that, frequently, difficulties have arisen in predicting the reactivity of individually subcritical components assembled in a critical array. It has been postulated that errors in the neutron leakage from individual elements in the array could be responsible for these problems. In these NIST measurements, an accurate determination of the leakage from a fission spectrum, modified by water scattering, is available. Previously, results for 3-, 4-, and 5-in. diam. water-filled spheres, both with and without cadmium covers over the fission chambers, were presented for four fissionable materials: 235 U, 238 U, 237 Np, and 239 Pu. Results were also given for ''dry'' systems, in which the water spheres were drained of water, with the results corresponding to essentially measurements of unmoderated 252 Cf spontaneous-fission neutrons. The calculated-to-experimental (C/E) values ranged from 0.94 to 1.01 for the dry systems and 0.93 to 1.05 for the wet systems, with experimental uncertainties ranging from 1.5 to 1.9%. These results indicated discrepancies that were clearly outside of the experimental uncertainties, and further investigation was suggested. This work updates the previous calculations with a comparison of the predicted C/E values with ENDF/B-V and ENDF/B-VI transport cross sections. Variations in the predicted C/E values that arise from the use of ENDF/B-V, ENDF/B-VI, ENDL92, and LLLDOS for the response fission cross sections are also tabulated. The use of both a 45-group NIST fission spectrum and a continuous-energy fission spectrum for 252 Cf are evaluated. The use of the generalized-linear-least-squares (GLLSM) procedures to investigate the reported discrepancies in the water sphere results for 235 U, 238 U, 239 Pu, and 237 Np is reported herein. These studies

  6. Size Effect on the Infrared Spectra of Condensed Media under Conditions of 1D, 2D, and 3D Dielectric Confinement

    KAUST Repository

    Shaganov, Igor I.

    2010-10-07

    The effect of dielectric confinement on the peak position of intramolecular and a lattice vibration in the infrared spectra of various condensed media is investigated. Liquid benzene, carbon disulfide, and chloroform, as well as amorphous SiO2 and microcrystalline MgO particles, were characterized in this study. The absorption spectra of organic liquids and aqueous solutions of a silica submicrometer powder were measured under a variety of dielectric confinement configurations using Fourier transform Infrared spectroscopy. A significant shift of the resonant absorption band of liquid mesoparticles has been observed under dielectric confinement, which is in good agreement with model predictions. A corresponding expression for the dielectric loss spectrum of an absorbing composite medium was obtained using a Maxwell-Garnett generalized equation for the cases of one, two, and three-dimensional dielectric confinement in both ordered and disordered thin layers (disks), rods (wires or needles), and spheres of an absorbing medium. The experimental data on peak positions obtained from the infrared spectra of the organic liquids investigated in this work, as well as from the infrared spectra of amorphous quartz spherical particles and rods, are in good agreement with the calculated data. It is shown using simulations of the absorption spectrum of MgO powder that the approach suggested can be applied under certain conditions to the modeling of the spectra of microcrystalline particles of nonspheroidal shape. © 2010 American Chemical Society.

  7. Improved Dielectric Films For Capacitors

    Science.gov (United States)

    Yen, Shiao-Ping S.; Lewis, Carol R.; Cygan, Peter J.; Jow, T. Richard

    1994-01-01

    Dielectric films made from blends of some commercially available high-dielectric-constant cyanoresins with each other and with cellulose triacetate (CTA) have both high dielectric constants and high breakdown strengths. Dielectric constants as high as 16.2. Films used to produce high-energy-density capacitors.

  8. Technical report: Electric field in not completely symmetric systems

    International Nuclear Information System (INIS)

    Vila, F.

    1994-08-01

    In this paper it is studied theoretically the electric field in the not completely symmetric system earthed metallic sphere-uniformly charged dielectric plan, for sphere surface points situated in the plan that contains sphere's center and vertical symmetry axe of dielectric plan. (author). 11 refs, 1 fig

  9. An experimental study of dielectric dispersion in porous media and its dependence on pore geometry

    Energy Technology Data Exchange (ETDEWEB)

    Haslund, E.

    1996-12-31

    Understanding water saturated composite media are important in the study of oil reservoirs. This doctoral thesis discusses measurements of the frequency dependent permittivity and conductivity of water saturated porous glass specimens. The experiments are designed to investigate the dispersion resulting from the geometrical properties of the pore space. Measurements are presented of the effective complex dielectric constant of water saturated porous glass specimens for frequencies below 13 MHz. The specimens are made from sintered glass spheres, and in some specimens thin plates are mixed in with the spheres. Low-conductivity water is used to saturate the pore space in order to scale the frequency range of the Maxwell-Wagner dispersion into the measurement range. The experiments are compared with two different effective medium approaches. One approach is the Mendelson and Cohen theory with randomly oriented spheroidal grains in addition to spherical grains, the other the Local porosity theory due to Hilfer. Both theories were found to be in good agreement with the experimental observations. 175 refs., 59 figs., 1 table

  10. Characterization of a dielectric phantom for high-field magnetic resonance imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Qi, E-mail: Qi.Duan@nih.gov; Duyn, Jeff H.; Gudino, Natalia; Zwart, Jacco A. de; Gelderen, Peter van [Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892 (United States); Sodickson, Daniel K.; Brown, Ryan [The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016 (United States)

    2014-10-15

    Purpose: In this work, a generic recipe for an inexpensive and nontoxic phantom was developed within a range of biologically relevant dielectric properties from 150 MHz to 4.5 GHz. Methods: The recipe includes deionized water as the solvent, NaCl to primarily control conductivity, sucrose to primarily control permittivity, agar–agar to gel the solution and reduce heat diffusivity, and benzoic acid to preserve the gel. Two hundred and seventeen samples were prepared to cover the feasible range of NaCl and sucrose concentrations. Their dielectric properties were measured using a commercial dielectric probe and were fitted to a 3D polynomial to generate a recipe describing the properties as a function of NaCl concentration, sucrose concentration, and frequency. Results: Results indicated that the intuitive linear and independent relationships between NaCl and conductivity and between sucrose and permittivity are not valid. A generic polynomial recipe was developed to characterize the complex relationship between the solutes and the resulting dielectric values and has been made publicly available as a web application. In representative mixtures developed to mimic brain and muscle tissue, less than 2% difference was observed between the predicted and measured conductivity and permittivity values. Conclusions: It is expected that the recipe will be useful for generating dielectric phantoms for general magnetic resonance imaging (MRI) coil development at high magnetic field strength, including coil safety evaluation as well as pulse sequence evaluation (including B{sub 1}{sup +} mapping, B{sub 1}{sup +} shimming, and selective excitation pulse design), and other non-MRI applications which require biologically equivalent dielectric properties.

  11. Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method

    Science.gov (United States)

    Gopi, D.; Indira, J.; Kavitha, L.; Sekar, M.; Mudali, U. Kamachi

    Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology.

  12. Energy harvesting from vibration of Timoshenko nanobeam under base excitation considering flexoelectric and elastic strain gradient effects

    Science.gov (United States)

    Managheb, S. A. M.; Ziaei-Rad, S.; Tikani, R.

    2018-05-01

    The coupling between polarization and strain gradients is called flexoelectricity. This phenomenon exists in all dielectrics with any symmetry. In this paper, energy harvesting from a Timoshenko beam is studied by considering the flexoelectric and strain gradient effects. General governing equations and related boundary conditions are derived using Hamilton's principle. The flexoelectric effects are defined by gradients of normal and shear strains which lead to a more general model. The developed model also covers the classical Timoshenko beam theory by ignoring the flexoelectric effect. Based on the developed model, flexoelectricity effect on dielectric beams and energy harvesting from cantilever beam under harmonic base excitation is investigated. A parametric study was conducted to evaluate the effects of flexoelectric coefficients, strain gradient constants, base acceleration and the attaching tip mass on the energy harvested from a cantilever Timoshenko beam. Results show that the flexoelectricity has a significant effect on the energy harvester performance, especially in submicron and nano scales. In addition, this effect makes the beam to behave softer than before and also it changes the harvester first resonance frequency. The present study provides guidance for flexoelectric nano-beam analysis and a method to evaluate the performance of energy harvester in nano-dielectric devices.

  13. Generating perfect fluid spheres in general relativity

    Science.gov (United States)

    Boonserm, Petarpa; Visser, Matt; Weinfurtner, Silke

    2005-06-01

    Ever since Karl Schwarzschild’s 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star—a static spherically symmetric blob of fluid with position-independent density—the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres.

  14. Generating perfect fluid spheres in general relativity

    International Nuclear Information System (INIS)

    Boonserm, Petarpa; Visser, Matt; Weinfurtner, Silke

    2005-01-01

    Ever since Karl Schwarzschild's 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star--a static spherically symmetric blob of fluid with position-independent density--the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres

  15. Dielectric function of two-phase colloid-polymer nanocomposite.

    Science.gov (United States)

    Mitzscherling, S; Cui, Q; Koopman, W; Bargheer, M

    2015-11-28

    The plasmon resonance of metal nanoparticles determines their optical response in the visible spectral range. Many details such as the electronic properties of gold near the particle surface and the local environment of the particles influence the spectra. We show how the cheap but highly precise fabrication of composite nanolayers by spin-assisted layer-by-layer deposition of polyelectrolytes can be used to investigate the spectral response of gold nanospheres (GNS) and gold nanorods (GNR) in a self-consistent way, using the established Maxwell-Garnett effective medium (MGEM) theory beyond the limit of homogeneous media. We show that the dielectric function of gold nanoparticles differs from the bulk value and experimentally characterize the shape and the surrounding of the particles thoroughly by SEM, AFM and ellipsometry. Averaging the dielectric functions of the layered surrounding by an appropriate weighting with the electric field intensity yields excellent agreement for the spectra of several nanoparticles and nanorods with various cover-layer thicknesses.

  16. Nonlinear electroelastic deformations of dielectric elastomer composites: II - Non-Gaussian elastic dielectrics

    Science.gov (United States)

    Lefèvre, Victor; Lopez-Pamies, Oscar

    2017-02-01

    This paper presents an analytical framework to construct approximate homogenization solutions for the macroscopic elastic dielectric response - under finite deformations and finite electric fields - of dielectric elastomer composites with two-phase isotropic particulate microstructures. The central idea consists in employing the homogenization solution derived in Part I of this work for ideal elastic dielectric composites within the context of a nonlinear comparison medium method - this is derived as an extension of the comparison medium method of Lopez-Pamies et al. (2013) in nonlinear elastostatics to the coupled realm of nonlinear electroelastostatics - to generate in turn a corresponding solution for composite materials with non-ideal elastic dielectric constituents. Complementary to this analytical framework, a hybrid finite-element formulation to construct homogenization solutions numerically (in three dimensions) is also presented. The proposed analytical framework is utilized to work out a general approximate homogenization solution for non-Gaussian dielectric elastomers filled with nonlinear elastic dielectric particles that may exhibit polarization saturation. The solution applies to arbitrary (non-percolative) isotropic distributions of filler particles. By construction, it is exact in the limit of small deformations and moderate electric fields. For finite deformations and finite electric fields, its accuracy is demonstrated by means of direct comparisons with finite-element solutions. Aimed at gaining physical insight into the extreme enhancement in electrostriction properties displayed by emerging dielectric elastomer composites, various cases wherein the filler particles are of poly- and mono-disperse sizes and exhibit different types of elastic dielectric behavior are discussed in detail. Contrary to an initial conjecture in the literature, it is found (inter alia) that the isotropic addition of a small volume fraction of stiff (semi

  17. Ceramic-polymer nanocomposites with increased dielectric permittivity and low dielectric loss

    International Nuclear Information System (INIS)

    Bhardwaj, Sumit; Paul, Joginder; Raina, K. K.; Thakur, N. S.; Kumar, Ravi

    2014-01-01

    The use of lead free materials in device fabrication is very essential from environmental point of view. We have synthesized the lead free ferroelectric polymer nanocomposite films with increased dielectric properties. Lead free bismuth titanate has been used as active ceramic nanofillers having crystallite size 24nm and PVDF as the polymer matrix. Ferroelectric β-phase of the polymer composite films was confirmed by X-ray diffraction pattern. Mapping data confirms the homogeneous dispersion of ceramic particles into the polymer matrix. Frequency dependent dielectric constant increases up to 43.4 at 100Hz, whereas dielectric loss decreases with 7 wt% bismuth titanate loading. This high dielectric constant lead free ferroelectric polymer films can be used for energy density applications

  18. Neutron spectrometry and dosimetry with neural networks and Bonner spheres: a study to reduce the spheres number

    International Nuclear Information System (INIS)

    Espinoza G, J. G.; Martinez B, M. R.; Leon P, A. A.; Hernandez P, C. F.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, J. M.; Vega C, H. R.; Mendez, R.; Gallego, E.; De Sousa L, M. A.

    2016-10-01

    For neutron spectrometry and neutron dosimetry, the Bonner spheres spectrometric system has been the most widely used system, however, the number, size and weight of the spheres composing the system, as well as the need to use a reconstruction code and the long periods of time used to carry out the measurements are some of the disadvantages of this system. For the reconstruction of the spectra, different techniques such as artificial neural networks of reverse propagation have been used. The objective of this work was to reduce the number of Bonner spheres and to use counting speeds in a reverse propagation neural network, optimized by means of the robust design methodology, to reconstruct the neutron spectra. For the design of the neural network we used the neutron spectra of the IAEA and the response matrix of the Bonner spheres with "6LiI(Eu) detector. The performance of the network was compared; using 7 Bonner spheres against other cases where only 2 and one sphere are used. The network topologies were trained 36 times for each case keeping constant the objective error (1E(-3)), the training algorithm was trains cg and the robust design methodology to determine the best network architectures. With these, the best and worst results were compared. The results obtained using 7 spheres were similar to those with the 5-in sphere, however is still in an information analysis stage. (Author)

  19. Public Sphere as Digital Assemblage

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    the 1990s onwards digitalization brought concepts of network and complexity into the theoretical discourse. This relational turn changed the social ontology of the public sphere into a dynamic and complex system, erasing the division between the fields of reality (the world), representation (discourse......Normative theories of public sphere have struggled with the topic of materiality. The historical narrative of the ‘public sphere’ situated the phenomenon in specific spaces, where practices (public deliberation) and language (discourse) constructed political agencies, and further publics. From......), and subjectivity (agency). This changed the public sphere into an assemblage consisting of both human and non-human actors interactingin a highly dynamic, networked environment. This paper proposes a framework for considering this new materiality in the field of the public sphere: the assemblage and complexity...

  20. Thin-dielectric-layer engineering for 3D nanostructure integration using an innovative planarization approach

    International Nuclear Information System (INIS)

    Guerfi, Y; Doucet, J B; Larrieu, G

    2015-01-01

    Three-dimensional (3D) nanostructures are emerging as promising building blocks for a large spectrum of applications. One critical issue in integration regards mastering the thin, flat, and chemically stable insulating layer that must be implemented on the nanostructure network in order to build striking nano-architectures. In this letter, we report an innovative method for nanoscale planarization on 3D nanostructures by using hydrogen silesquioxane as a spin-on-glass (SOG) dielectric material. To decouple the thickness of the final layer from the height of the nanostructure, we propose to embed the nanowire network in the insulator layer by exploiting the planarizing properties of the SOG approach. To achieve the desired dielectric thickness, the structure is chemically etched back with a highly diluted solution to control the etch rate precisely. The roughness of the top surface was less than 2 nm. There were no surface defects and the planarity was excellent, even in the vicinity of the nanowires. This newly developed process was used to realize a multilevel stack architecture with sub-deca-nanometer-range layer thickness. (paper)

  1. Indentation analysis of nano-particle using nano-contact mechanics models during nano-manipulation based on atomic force microscopy

    International Nuclear Information System (INIS)

    Daeinabi, Khadijeh; Korayem, Moharam Habibnejad

    2011-01-01

    Atomic force microscopy is applied to measure intermolecular forces and mechanical properties of materials, nano-particle manipulation, surface scanning and imaging with atomic accuracy in the nano-world. During nano-manipulation process, contact forces cause indentation in contact area between nano-particle and tip/substrate which is considerable at nano-scale and affects the nano-manipulation process. Several nano-contact mechanics models such as Hertz, Derjaguin–Muller–Toporov (DMT), Johnson–Kendall–Roberts–Sperling (JKRS), Burnham–Colton–Pollock (BCP), Maugis–Dugdale (MD), Carpick–Ogletree–Salmeron (COS), Pietrement–Troyon (PT), and Sun et al. have been applied as the continuum mechanics approaches at nano-scale. In this article, indentation depth and contact radius between tip and substrate with nano-particle for both spherical and conical tip shape during nano-manipulation process are analyzed and compared by applying theoretical, semiempirical, and empirical nano-contact mechanics models. The effects of adhesion force, as the main contrast point in different nano-contact mechanics models, on nano-manipulation analysis is investigated for different contact radius, and the critical point is discussed for mentioned models.

  2. Dielectric Properties of PE/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    E. David

    2013-01-01

    Full Text Available Polyethylene/nanoclay specimens containing from 0 to 5% nanoclays were prepared from a commercially available premixed PE/nanoclay masterbatch containing 50% wt of nanoclay. The masterbatch was diluted to the desired concentration by adding PE along with various amounts of compatibilizer in order to achieve the best possible dispersion of the nanoclay platelets. The dielectric response of the compounded samples was investigated using a combination of time and frequency-domain spectroscopy in order to cover a wide frequency window. Both techniques were in good agreement when the time-domain data was transformed into frequency-domain data. Despite their low concentration, the addition of the dispersed nanoclays led to a significant alteration of the material dielectric response in the form of the appearance of various interfacial relaxation processes and an increase of charge carrier transport within the insulation material. Moreover, an onset of nonlinear charge transport process was observed at moderate fields for specimens containing a relatively low level of nanoclays. The high-field breakdown strength was shown to have been improved by the incorporation of the nanoparticles, particularly when the exfoliation was enhanced by the use of a maleic anhydride grafted polyethylene compatibilizer.

  3. Optical Properties of Zinc Oxide Nano-particles Embedded in Dielectric Medium for UV region: Numerical Simulation

    International Nuclear Information System (INIS)

    Al-Hilli, S. M.; Willander, M.

    2006-01-01

    Zinc oxide nano-particles have been used by cosmetic industry for many years because they are extensively used as agents to attenuate (absorb and/or scatter) the ultraviolet radiation. In the most UV-attenuating agent is formulated in which the metal oxide nano-particles are incorporated into liquid media or polymer media are manufactured, such as sunscreens and skin care cosmetics. In this paper we study the wavelength dependence on the particle size (r eff = 10-100 nm) by solving the scattering problem of hexagonal ZnO particle for different shapes (plate, equal ratio, column) using the discrete dipole approximation method to find the absorption, scattering, and extinction efficiencies for the UV region (30-400 nm). A new modified hexagonal shape is introduced to determine the scattering problem and it is assumed in this study that the wavelength is comparable to the particle size. From these results, we conclude that the optimum particle radius to block the UV radiation is between r eff = 40-80 nm

  4. Optical Properties of Zinc Oxide Nano-particles Embedded in Dielectric Medium for UV region: Numerical Simulation

    Science.gov (United States)

    Al-Hilli, S. M.; Willander, M.

    2006-02-01

    Zinc oxide nano-particles have been used by cosmetic industry for many years because they are extensively used as agents to attenuate (absorb and/or scatter) the ultraviolet radiation. In the most UV-attenuating agent is formulated in which the metal oxide nano-particles are incorporated into liquid media or polymer media are manufactured, such as sunscreens and skin care cosmetics. In this paper we study the wavelength dependence on the particle size ( r eff = 10-100 nm) by solving the scattering problem of hexagonal ZnO particle for different shapes (plate, equal ratio, column) using the discrete dipole approximation method to find the absorption, scattering, and extinction efficiencies for the UV region (30-400 nm). A new modified hexagonal shape is introduced to determine the scattering problem and it is assumed in this study that the wavelength is comparable to the particle size. From these results, we conclude that the optimum particle radius to block the UV radiation is between r eff = 40-80 nm.

  5. Synthesis and characterization of a-site doped LaTiO3 nano perovskites

    International Nuclear Information System (INIS)

    Bradha, M.; Ashok, Anuradha

    2013-01-01

    Nano-sized lanthanum titanate perovskites (La (1-x) A x TiO 3 ) (A= Ba, Sr, Ca) were prepared by sol-gel method and calcined at 800℃. The synthesised perovskites were characterized by Thermogravimetry/ Differential thermal analysis (TGA/DTA), X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM) etc. LaTiO 3 is a perovskite having prominent interest for a variety of applications such as dielectric, insulators, charge-transport properties etc. It is a defect perovskite, with transport properties varying from insulating to metallic based on oxygen stoichiometry. In a quest to observe the effect of the nano size on its properties, lanthanum titanate (LaTiO 3 ) nano perovskites with different dopants on the A-site were prepared by using sol-gel method. In the present work we discuss the synthesis and structural analysis of (La 0.8 A 0.2 TiO 3 ). Phase purity and structural analysis of the calcined samples were performed by powder X-ray diffraction (XRD, with CuKα radiation). In addition to this, morphology and crystal structure was examined by Transmission Electron Microscopy (TEM) using a JEOL JEM 2100 HRTEM. HRTEM studies indicate that the nano perovskites are of size around 20 nm. Ring pattern in SAED also confirms that the perovskite is polycrystalline/nanocrystalline. More detailed study on high resolution images and crystal structure shed light on the reason for the properties exhibited by this perovskites

  6. Lithium ion conducting PVA:PVdF polymer electrolytes doped with nano SiO2 and TiO2 filler

    Science.gov (United States)

    Hema, M.; Tamilselvi, P.

    2016-09-01

    The effect of nano SiO2 and TiO2 fillers on the thermal, mechanical and electrochemical properties of PVA:PVdF:LiCF3SO3 have been investigated by three optimized systems of SPE (80PVA:20PVdF:15LiCF3SO3), CPE-I (SPE:8SiO2) and CPE-II (SPE:4TiO2). From the TGA curve least weight loss has been observed for CPE-II indicating high thermal stability compared to other systems. Stress-strain curve of the prepared samples confirm the enhancement of tensile strength in CPE-II compared to CPE-I and SPE. Conductivity studies show that addition of TiO2 filler slightly enhances ionic conductivity 3.7×10-3 S cm-1 compared to filler free system at 303 K. Dielectric plots have been analyzed and CPE-II possesses higher dielectric constant compared to CPE-I and filler free system. Temperature dependence of modulus plots has been studied for highest conductivity possessing sample. Wider electrochemical stability has been obtained for nano-composite polymer electrolytes. The results conclude that the prepared CPE-II shows the best performance and it will be well suited for lithium ion batteries.

  7. Book Review: Nano physics & Nano technology

    Directory of Open Access Journals (Sweden)

    Abdolkhaled Zaree

    2012-12-01

    Full Text Available During last decades, there are a lot of emphases on studying material behavior in atomic scale. In most scientific and engineering fields, one can see the effect of nanotechnology. The aim of nanoscience is to design and fabrication of new and applicable materials. Nowadays, Nano is a popular science which chemists, physicist, doctors, engineers, financial managers and environment's fans for creating a good life via nanoscience have a great cooperation with each others. Materials in nano scale such as nanotubes and nanowires have extraordinary properties which by optimization of these properties in nano scale and then develop these properties to macro scale, they've been challenging issues. For instance, materials in nano scale improve mechanical properties of polymers and metallic materials via nano particles and on the other hand by producing a thin film on surfaces improve surface hardening. Besides, nanotechnology is in hi-tech industries such as magnetic devices, surface coating, and biomaterial, material having sensors, polymers, gels, ceramics and intelligent membrane. Nano-carbon tubes are considered intelligent due to the fact that they couple electrochemical and elastic properties simultaneously, hence have greater activation energy density in comparison with other intelligent materials. Studying nanoscience is important because it causes the life to be better. Future Materials and structures will have a lot of outstanding properties. Intelligent machines can repair, recycle and reconstruct themselves. All these features are only possible in nano zone. Nano in engineering science can provide the possibility of making light missiles for exploring space. The reduced weight can be achieved by replacing traditional materials with hybrid nanocomposites.

  8. Organic field-effect transistor nonvolatile memories utilizing sputtered C nanoparticles as nano-floating-gate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Liu, Chang-Hai; She, Xiao-Jian; Sun, Qi-Jun; Gao, Xu; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)

    2014-10-20

    High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories.

  9. Organic field-effect transistor nonvolatile memories utilizing sputtered C nanoparticles as nano-floating-gate

    International Nuclear Information System (INIS)

    Liu, Jie; Liu, Chang-Hai; She, Xiao-Jian; Sun, Qi-Jun; Gao, Xu; Wang, Sui-Dong

    2014-01-01

    High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories.

  10. Cobalt oxide polymorph growth on electrostatic self-assembled nanoparticle arrays for dually tunable nano-textures

    International Nuclear Information System (INIS)

    Bulliard, Xavier; Benayad, Anass; Lee, Kwang-Hee; Choi, Yun-Hyuk; Lee, Jae Cheol; Park, Jong-Jin; Kim, Jong-Min

    2011-01-01

    We report on a method for surface nano-texturing on a plastic substrate. Nano-objects with a silica nanoparticle core and a textured cobalt oxide crown are created with selectable density on the plastic substrate. The resulting dual morphology is easily tuned over large areas, either by changing the parameters directing nanoparticle deposition through electrostatic self-arrangement for nano-object density control, or the parameter directing cobalt oxide deposition for shape control. The entire process takes place at room temperature, with no chemicals harmful to the plastic substrate. The ready modulation of the dual morphology is used to control the wettability properties of the plastic film, which is covered by nano-objects.

  11. Modeling of a piezoelectric/piezomagnetic nano energy harvester based on two dimensional theory

    Science.gov (United States)

    Yan, Zhi

    2018-01-01

    This work presents a two dimensional theory for a piezoelectric/piezomagnetic bilayer nanoplate in coupled extensional and flexural vibrations with both flexoelectric and surface effects. The magneto-electro-elastic (MEE) coupling equations are derived from three-dimensional equations and Kirchhoff plate theory. Based on the developed theory, a piezoelectric/piezomagnetic nano energy harvester is proposed, which can generate electricity under time-harmonic applied magnetic field. The approximate solutions for the mechanical responses and voltage of the energy harvester are obtained using the weighted residual method. Results show that the properties of the proposed energy harvester are size-dependent due to the flexoelectric and surface effects, and such effects are more pronounced when the bilayer thickness is reduced to dozens of nanometers. It is also found that the magnetoelectric coupling coefficient and power density of the energy harvester are sensitive to the load resistance, the thickness fraction of the piezoelectric or the piezomagnetic layer and damping ratios. Moreover, results indicate that the flexoelectric effect could be made use to build a dielectric/piezomagnetic nano energy harvester. This work provides modeling techniques and numerical methods for investigating the size-dependent properties of MEE nanoplate-based energy harvester and could be helpful for designing nano energy harvesters using the principle of flexoelectricity.

  12. Dielectric effect on electric fields in the vicinity of the metal–vacuum–dielectric junction

    International Nuclear Information System (INIS)

    Chung, M.S.; Mayer, A.; Miskovsky, N.M.; Weiss, B.L.; Cutler, P.H.

    2013-01-01

    The dielectric effect was theoretically investigated in order to describe the electric field in the vicinity of a junction of a metal, dielectric, and vacuum. The assumption of two-dimensional symmetry of the junction leads to a simple analytic form and to a systematic numerical calculation for the field. The electric field obtained for the triple junction was found to be enhanced or reduced according to a certain criterion determined by the contact angles and dielectric constant. Further numerical calculations of the dielectric effect show that an electric field can experience a larger enhancement or reduction for a quadruple junction than that achieved for the triple junction. It was also found that even though it changes slowly in comparison with the shape effect, the dielectric effect was noticeably large over the entire range of the shape change. - Highlights: ► This work explains how a very strong electric field can be produced due to the dielectric in the vicinity of metal–dielectric contact. ► This work deals with configurations which enhance electric fields using the dielectric effect. The configuration is a type of junction at which metal, vacuum and dielectric meet. ► This work suggests the criterion to determine whether field enhancement occurs or not in the triple junction of metal, vacuum and dielectric. ► This work suggests that a quadruple junction is more effective in enhancing the electric field than a triple junction. The quadruple junction is formed by an additional vacuum portion to the triple junction. ► This work suggests that a triple junction can be a breakthrough candidate for a cold electron source

  13. Interconnect Between a Waveguide and a Dielectric Waveguide Comprising an Impedance Matched Dielectric Lens

    Science.gov (United States)

    Decrossas, Emmanuel (Inventor); Chattopadhyay, Goutam (Inventor); Chahat, Nacer (Inventor); Tang, Adrian J. (Inventor)

    2016-01-01

    A lens for interconnecting a metallic waveguide with a dielectric waveguide is provided. The lens may be coupled a metallic waveguide and a dielectric waveguide, and minimize a signal loss between the metallic waveguide and the dielectric waveguide.

  14. Reduction of space charge breakdown in e-beam irradiated nano/polymethyl methacrylate composites

    International Nuclear Information System (INIS)

    Zheng Feihu; Zhang Yewen; An Zhenlian; Dong Jianxing; Lei Qingquan

    2013-01-01

    Fast discharge of numerous space charges in dielectric materials can cause space charge breakdown. This letter reports the role of nanoparticles in affecting space charge breakdown of nano/polymethyl methacrylate composites. Space charge distributions in the composites, implanted by electron beam irradiation, were measured by pressure wave propagation method. The results show that the nanoparticles have significant effects on the isothermal charge decay and space charge breakdown in the nanocomposites. The resistance to space charge breakdown in the nanocomposites is attributed to the combined action of the introduction of deep trapping states and the scattering effect by the added nanoparticles.

  15. Dentinal tubule occluding capability of nano-hydroxyapatite; The in-vitro evaluation.

    Science.gov (United States)

    Baglar, Serdar; Erdem, Umit; Dogan, Mustafa; Turkoz, Mustafa

    2018-04-29

    In this in-vitro study, the effectiveness of experimental pure nano-hydroxyapatite (nHAP) and 1%, 2%, and 3% F¯ doped nano-HAp on dentine tubule occlusion was investigated. And also, the cytotoxicity of materials used in the experiment was evaluated. Nano-HAp types were synthesized by the precipitation method. Forty dentin specimens were randomly divided into five groups of; 1-no treatment (control), 2-specimens treated with 10% pure nano-HAp and 3, 4, 5 specimens treated with 1%, 2%, and 3% F - doped 10% nano-HAp, respectively. To evaluate the effectiveness of the materials used; pH, FTIR, and scanning electron microscopy evaluations were performed before and after degredation in simulated body fluid. To determine cytotoxicity of the materials, MTT assay was performed. Statistical evaluations were performed with F and t tests. All of the nano-HAp materials used in this study built up an effective covering layer on the dentin surfaces even with plugs in tubules. It was found that this layer had also a resistance to degradation. None of the evaluated nano-HAp types were have toxicity. Fluoride doping showed a positive effect on physical and chemical stability until a critical value of 1% F - . The all evaluated nano-HAp types may be effectively used in dentin hypersensitivity treatment. The formed nano-HAp layers were seem to resistant to hydrolic deletion. The pure and 1% F - doped nano-HAp showed the highest biocompatibility thus it was assessed that pure and 1% F - doped materials may be used as an active ingredient in dentin hypersensitivity agents. © 2018 Wiley Periodicals, Inc.

  16. Safety assessment of nanomaterials using an advanced decision-making framework, the DF4nanoGrouping

    Science.gov (United States)

    Landsiedel, Robert; Ma-Hock, Lan; Wiench, Karin; Wohlleben, Wendel; Sauer, Ursula G.

    2017-05-01

    As presented at the 2016 TechConnect World Innovation Conference on 22-25 May 2016 in Washington DC, USA, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) `Nano Task Force' proposes a Decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping) consisting of three tiers to assign nanomaterials to four main groups with possible further subgrouping to refine specific information needs. The DF4nanoGrouping covers all relevant aspects of a nanomaterial's life cycle and biological pathways: intrinsic material properties and system-dependent properties (that depend upon the nanomaterial's respective surroundings), biopersistence, uptake and biodistribution, and cellular and apical toxic effects. Use, release, and exposure route may be applied as `qualifiers' to determine if, e.g., nanomaterials cannot be released from products, which may justify waiving of testing. The four main groups encompass (1) soluble, (2) biopersistent high aspect ratio, (3) passive, and (4) active nanomaterials. The DF4nanoGrouping foresees a stepwise evaluation of nanomaterial properties and effects with increasing biological complexity. In case studies covering carbonaceous nanomaterials, metal oxide, and metal sulfate nanomaterials, amorphous silica and organic pigments (all nanomaterials having primary particle sizes below 100 nm), the usefulness of the DF4nanoGrouping for nanomaterial hazard assessment was confirmed. The DF4nanoGrouping facilitates grouping and targeted testing of nanomaterials. It ensures that sufficient data for the risk assessment of a nanomaterial are available, and it fosters the use of non-animal methods. No studies are performed that do not provide crucial data. Thereby, the DF4nanoGrouping serves to save both animals and resources.

  17. Method for producing small hollow spheres

    International Nuclear Information System (INIS)

    Hendricks, C.D.

    1979-01-01

    A method is described for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T >approx. 600 0 C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 10 3 μm) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants

  18. Optimal Super Dielectric Material

    Science.gov (United States)

    2015-09-01

    plate capacitor will reduce the net field to an unprecedented extent. This family of materials can form materials with dielectric values orders of... Capacitor -Increase Area (A)............8 b. Multi-layer Ceramic Capacitor -Decrease Thickness (d) .......10 c. Super Dielectric Material-Increase...circuit modeling, from [44], and B) SDM capacitor charge and discharge ...................................................22 Figure 15. Dielectric

  19. Cavity formation by the impact of Leidenfrost spheres

    KAUST Repository

    Marston, Jeremy

    2012-05-01

    We report observations of cavity formation and subsequent collapse when a heated sphere impacts onto a liquid pool. When the sphere temperature is much greater than the boiling point of the liquid, we observe an inverted Leidenfrost effect where the sphere is encompassed by a vapour layer that prevents physical contact with the liquid. This creates the ultimate non-wetting scenario during sphere penetration through a free surface, producing very smooth cavity walls. In some cases during initial entry, however, the liquid contacts the sphere at the equator, leading to the formation of a dual cavity structure. For cold sphere impacts, where a contact line is observed, we reveal details of the contact line pinning, which initially forms a sawtooth pattern. We also observe surface waves on the cavity interface for cold spheres. We compare our experimental results to previous studies of cavity dynamics and, in particular, the influence of hydrophobicity on the entry of the sphere. © 2012 Cambridge University Press.

  20. Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

    Directory of Open Access Journals (Sweden)

    Medeiros Jamilson Pinto

    1998-01-01

    Full Text Available Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

  1. Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

    Science.gov (United States)

    Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

    2018-01-01

    We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

  2. Excellent microwave response derived from the construction of dielectric-loss 1D nanostructure

    Science.gov (United States)

    Dai, Sisi; Quan, Bin; Liang, Xiaohui; Lv, Jing; Yang, Zhihong; Ji, Guangbin; Du, Youwei

    2018-05-01

    Increasing efforts have recently been devoted to the artificial design and function of nanostructures for their application prospects in catalysis, drug delivery, energy storage, and microwave absorption. With the advantages of natural abundance, low cost, and environment friendliness, a one-dimensional (1D) MnO2 nanowire (MW) is the representative dielectric-loss absorber for its special morphology and crystalline structure. However, its low reflection loss (RL) value due to its thin thickness limits its wide development and application in the microwave absorption field. In this work, artificially designed MnO2@AIR@C (MCs), namely, 1D hollow carbon nanotubes filled with nano-MnO2, were designed and synthesized. It is found that the RL value of the MC is almost lower than -10 dB. Furthermore, the RL value was able to achieve -18.9 dB with an effective bandwidth (-10 dB) of 5.84 GHz at 2.25 mm. Simultaneously, the dielectric and interfacial polarization became stronger while the impedance matching was much better than in the single MWs. Hence, the rational design and fabrication of micro-architecture are essential and MC has great potential to be an outstanding microwave absorber.

  3. Electro-mechanical properties of free standing micro- and nano-scale polymer-ceramic composites for energy density capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Paritosh; Borkar, Hitesh [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India); Singh, B.P.; Singh, V.N. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Kumar, Ashok, E-mail: ashok553@nplindia.org [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India)

    2015-11-05

    The integration of inorganic fillers in polymer matrix is useful for superior mechanical strength and functional properties of polymer-ceramic composites. We report the fabrication and characterization of polyvinylidene fluoride-CoFe{sub 2}O{sub 4} (PVDF-CFO) (wt% 80:20, respectively) and PVDF-Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3}–CoFe{sub 2}O{sub 4} (PVDF-PZT-CFO) (wt% 80:10:10, respectively) free standing 50 μm thick ferroelectric-polymer-ceramic composites films. X-ray diffraction (XRD) patterns and Raman spectra revealed the presence of major semi-crystalline β-PVDF along with α-phase which is responsible for ferroelectric nature in both the composite systems. Ferroelectric, dielectric and mechanical strength measurements were performed in order to evaluate the effects of CFO and PZT inorganic fillers in PVDF matrix. The inclusion of CFO and PZT micro-/nano-particles in PVDF polymer matrix improved the polarization behavior, dielectric properties and mechanical strength. The energy density was calculated by polarization-electric field hysteresis loop and found in the range of 6–8 J/cm{sup 3} may be useful for microelectronics. - Graphical abstract: Large area PVDF-PZT-CFO nano- and micro-composite films have been fabricated for high energy density storage flexible capacitor. Presence of nanocrystalline PZT and CFO particles in polymer matrix significantly enhanced their energy density capacity. - Highlights: • Physical interaction of cobalt iron oxide with polymer matrix results β-PVDF phase. • Evidence of Micro and Nano crystalline CFO and PZT fillers in polymer matrix. • The CFO and PZT fillers provide better mechanical strength to composite films. • PVDF-ceramic nanocomposites show low leakage behavior for high electric field.

  4. Nano- and micro-electromechanical systems fundamentals of nano- and microengineering

    CERN Document Server

    Lyshevski, Sergey Edward

    2005-01-01

    NANOTECHNOLOGY AND MICROTECHNOLOGY (NANO- AND MICRO- SCIENCE, ENGINEERING AND TECHNOLOGY), AND BEYOND Introduction and Overview: From Micro- to Nano- and Beyond to Stringo-Scale Introductory Definitions to the Subjects Current Developments and Needs for Coherent Revolutionary Developments Societal Challenges and Implications NANO- AND MICROSCALE SYSTEMS, DEVICES, AND STRUCTURES Sizing Features: From Micro- to Nano-, and from Nano- to Stringo-Scale MEMS and NEMS Definitions Introduction to Taxonomy of Nano- and Microsystem Synthesis and Design Introduction to Design and Optimization of Nano- and Microsystems in the Behavioral Domain NANO- AND MICROSYSTEMS: CLASSIFICATION AND CONSIDERATION Biomimetics, Biological Analogies,and Design of NEMS and MEMS Micro- and Nanoelectromechanical Systems: Scaling Laws and Mathematical Modeling MEMS Examples and MEMS Architectures Introduction to Microfabrication and Micromachining FUNDAMENTALS OF MICROFABRICATION AND MEMS FABRICATION TECHNOLOGIES Introducti...

  5. Dielectric Metamaterial Reflector

    Science.gov (United States)

    2017-02-14

    evaporation rates. The design also includes a glass window to enable monitoring of the film growth process. The cell design will allow films to be...we consider a thin SiO2 coating on the InP spheres, as shown in Fig. 1(a), to allow for tuning of the periodicity of the close-packed structure...packed high-index InP spheres with SiO2 coatings. The structure consists of three layers of 360 nm indium-phosphide spheres with 60-nm-thick SiO2

  6. Improving dielectric permittivity by incorporating PDMS-PEG block copolymer into PDMS network

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxane (PDMS) based elastomers are well-known to actuate with large strain mainly due to their low modulus and their non-conducting nature. On the other hand, polyethyleneglycols(PEG) are not stretchable but they have high permittivity and are conductive. Combination of the two...... polymers as a block copolymer depicts a possibility for substantial improvement of properties such as high permittivity and non-conductivity – if carefully designed. The objective is to synthesize PDMS-PEG multiblock copolymer assembling into different morphologies1 such as lamellar,cylinder, gyroid...... and spheres based on variation of volume fractions of PDMS and PEG. The synthesisis amended from Klasner et al.2 and Jukarainen et al.3 Variation in the ratio between the two constituents introduces distinctive properties in terms of dielectric permittivity and rheological behaviour. PDMS-PEG multiblock...

  7. Nano dentistry

    International Nuclear Information System (INIS)

    Oh, S.; Park, Y.B.; Kim, S.; Jin, S.

    2014-01-01

    Nano technology in dentistry has drawn many scientists’ and clinicians’ attention to significant advances in the diagnosis, treatment, and prevention of oral disease. Also, nano materials in dentistry have been studied to overcome the physical and chemical characteristics of conventional dental materials. These interesting facts are the motivation of this special issue. The presented issue provides a variety of topics in the field of dentistry such as novel nano filled composite resin, the cytotoxicity of nanoparticles deposited on orthodontic bands, the osseointegration of 3D nano scaffold, and nano surface treated implant.

  8. Dielectric study on hierarchical water structures restricted in cement and wood materials

    International Nuclear Information System (INIS)

    Abe, Fumiya; Nishi, Akihiro; Saito, Hironobu; Asano, Megumi; Watanabe, Seiei; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Fukuzaki, Minoru; Sudo, Seiichi; Suzuki, Youki

    2017-01-01

    Dielectric relaxation processes for mortar observed by broadband dielectric spectroscopy were analyzed in the drying and hydration processes for an aging sample in the frequency region from 1 MHz up to 2 MHz. At least two processes for structured water in the kHz frequency region and another mHz relaxation process affected by ionic behaviors were observed. Comparison of the relaxation parameters obtained for the drying and hydration processes suggests an existence of hierarchical water structures in the exchange of water molecules, which are originally exchanged from free water observed at around 20 GHz. The water molecules reflected in the lower frequency process of the two kHz relaxation processes are more restricted and take more homogeneous structures than the higher kHz relaxation process. These structured water usually hidden in large ionic behaviors for wood samples was observed by electrodes covered by a thin Teflon film, and hierarchical water structures were also suggested for wood samples. Dielectric spectroscopy technique is an effective tool to analyze the new concept of hierarchical water structures in complex materials. (paper)

  9. Tessellating the Sphere with Regular Polygons

    Science.gov (United States)

    Soto-Johnson, Hortensia; Bechthold, Dawn

    2004-01-01

    Tessellations in the Euclidean plane and regular polygons that tessellate the sphere are reviewed. The regular polygons that can possibly tesellate the sphere are spherical triangles, squares and pentagons.

  10. Spherical nano-SnSb/MCMB/carbon core–shell composite for high stability lithium ion battery anodes

    International Nuclear Information System (INIS)

    Li, Juan; Ru, Qiang; Hu, Shejun; Sun, Dawei; Zhang, Beibei; Hou, Xianhua

    2013-01-01

    A novel multi-step design of spherical nano-SnSb/MCMB/carbon core–shell composite for high stability and long life lithium battery electrodes has been introduced. The core–shell composite was successfully synthesized via co-precipitation and subsequent pyrolysis. The resultant composite sphere consisted of nanosized SnSb alloy and mesophase carbon microbeads (MCMB, 10 μm) embedded in a carbon matrix pyrolyzed from glucose and petroleum pitch, in which the MCMB was treated to be the inner core to offer mechanical support and efficient electron conducting pathway. The composite material exhibited a unique stability with a retention discharge capacity rate of 83.52% with reversible capacity of 422.5 mAh g −1 after 100 cycles and a high initial coulombic efficiency of 83.53%. The enhanced electrochemical performance is attributed to the structural stability of the composite sphere during the charging–discharging process

  11. Nano-laminate vs. direct deposition of high permittivity gadolinium scandate on silicon by high pressure sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Feijoo, P.C., E-mail: pedronska@fis.ucm.es [Dpto. Física Aplicada III (Electricidad y Electrónica), Universidad Complutense de Madrid, Fac. de CC. Físicas. Av/Complutense S/N, E-28040 Madrid (Spain); Pampillón, M.A.; San Andrés, E. [Dpto. Física Aplicada III (Electricidad y Electrónica), Universidad Complutense de Madrid, Fac. de CC. Físicas. Av/Complutense S/N, E-28040 Madrid (Spain); Fierro, J.L.G. [Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas, C/Marie Curie 2, E-28049 Cantoblanco (Spain)

    2015-10-30

    In this work we use the high pressure sputtering technique to deposit the high permittivity dielectric gadolinium scandate on silicon substrates. This nonconventional deposition technique prevents substrate damage and allows for growth of ternary compounds with controlled composition. Two different approaches were assessed: the first one consists of depositing the material directly from a stoichiometric GdScO{sub 3} target; in the second one, we anneal a nano-laminate of < 0.5 nm thick Gd{sub 2}O{sub 3} and Sc{sub 2}O{sub 3} films in order to control the composition of the scandate. Metal–insulator–semiconductor capacitors were fabricated with platinum gates for electrical characterization. Accordingly, we grew a Gd-rich Gd{sub 2−x}Sc{sub x}O{sub 3} film that, in spite of higher leakage currents, presents a better effective relative permittivity of 21 and lower density of defects. - Highlights: • GdScO is deposited on Si as a high permittivity dielectric by two procedures. • Films sputtered from GdScO{sub 3} target are Sc-rich and present thick interface SiO{sub x}. • Gd-rich GdScO is obtained from a nano-laminate sputtered from Sc{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}. • Gd{sub 1.8}Sc{sub 0.2}O{sub 3} shows good effective permittivity and electrical properties.

  12. Robust, Flexible and Lightweight Dielectric Barrier Discharge Actuators Using Nanofoams/Aerogels

    Science.gov (United States)

    Sauti, Godfrey (Inventor); Xu, Tian-Bing (Inventor); Siochi, Emilie J. (Inventor); Wilkinson, Stephen P. (Inventor); Meador, Mary Ann B. (Inventor); Guo, Haiquan N. (Inventor)

    2015-01-01

    Robust, flexible, lightweight, low profile enhanced performance dielectric barrier discharge actuators (plasma actuators) based on aerogels/nanofoams with controlled pore size and size distribution as well as pore shape. The plasma actuators offer high body force as well as high force to weight ratios (thrust density). The flexibility and mechanical robustness of the actuators allows them to be shaped to conform to the surface to which they are applied. Carbon nanotube (CNT) based electrodes serve to further decrease the weight and profile of the actuators while maintaining flexibility while insulating nano-inclusions in the matrix enable tailoring of the mechanical properties. Such actuators are required for flow control in aeronautics and moving machinery such as wind turbines, noise abatement in landing gear and rotary wing aircraft and other applications.

  13. Raman scattering enhancement in photon-plasmon resonance mediated metal-dielectric microcavity

    International Nuclear Information System (INIS)

    Guddala, Sriram; Narayana Rao, D.; Dwivedi, Vindesh K.; Vijaya Prakash, G.

    2013-01-01

    Here, we report the photon-plasmon interaction scheme and enhanced field strengths resulted into the amplification of phonon in a novel microcavity. A metal-dielectric microcavity, with unified cavity photonic mode and localized surface plasmon resonances, is visualized by impregnating the gold nanoparticles into the deep see-through nano-sized pores of porous silicon microcavity. The intense optical field strengths resulting from the photon-plasmon interactions are probed by both resonant and non-resonant Raman scattering experiments. Due to photon-plasmon-phonon interaction mechanism, several orders of enhancement in the intensity of scattered Raman Stokes photon (at 500 cm −1 ) are observed. Our metal nanoparticle-microcavity hybrid system shows the potential to improve the sensing figure of merit as well as the applications of plasmonics for optoelectronics, photovoltaics, and related technologies

  14. Semiconductor Nano wires and Nano tubes: From Fundamentals to Diverse Applications

    International Nuclear Information System (INIS)

    Xiong, Q.; Grimes, C.A.; Zacharias, M.; Morral, A.F.; Hiruma, K.; Shen, G.

    2012-01-01

    Research in the field of semiconductor nano wires (SNWs) and nano tubes has been progressing into a mature subject with several highly interdisciplinary sub areas such as nano electronics, nano photonics, nano composites, bio sensing, optoelectronics, and solar cells. SNWs represent a unique system with novel properties associated to their one-dimensional (1D) structures. The fundamental physics concerning the formation of discrete 1D subbands, coulomb blockade effects, ballistic transport, and many-body phenomena in 1D nano wires and nano tubes provide a strong platform to explore the various scientific aspects in these nano structures. A rich variety of preparation methods have already been developed for generating well-controlled 1D nano structures and from a broad range of materials. The present special issue focuses on the recent development in the mechanistic understanding of the synthesis, the studies on electrical/optical properties of nano wires and their applications in nano electronics, nano photonics, and solar-energy harvesting. In this special issue, we have several invited review articles and contributed papers that are addressing current status of the fundamental issues related to synthesis and the diverse applications of semiconducting nano wires and nano tubes. One of the papers reviews the progress of the top-down approach of developing silicon-based vertically aligned nano wires to explore novel device architectures and integration schemes for nano electronics and clean energy applications. Another paper reviews the recent developments and experimental evidences of probing the confined optical and acoustic phonon in nonpolar semiconducting (Si and Ge) nano wires using Raman spectroscopy. The paper by K. Hiruma et al. spotlights the III semiconductor nano wires and demonstrates selective-area metal organic vapor phase epitaxy grown GaAs/In(Al)GaAs and InP/InAs/InP nano wires with heterojunctions along their axial and radial directions. The paper

  15. Dielectric Behavior of Low Microwave Loss Unit Cell for All Dielectric Metamaterial

    Directory of Open Access Journals (Sweden)

    Tianhuan Luo

    2015-01-01

    Full Text Available With a deep study of the metamaterial, its unit cells have been widely extended from metals to dielectrics. The dielectric based unit cells attract much attention because of the advantage of easy preparation, tunability, and higher frequency response, and so forth. Using the conventional solid state method, we prepared a kind of incipient ferroelectrics (calcium titanate, CaTiO3 with higher microwave permittivity and lower loss, which can be successfully used to construct metamaterials. The temperature and frequency dependence of dielectric constant are also measured under different sintering temperatures. The dielectric spectra showed a slight permittivity decrease with the increase of temperature and exhibited a loss of 0.0005, combined with a higher microwave dielectric constant of ~167 and quality factor Q of 2049. Therefore, CaTiO3 is a kind of versatile and potential metamaterial unit cell. The permittivity of CaTiO3 at higher microwave frequency was also examined in the rectangular waveguide and we got the permittivity of 165, creating a new method to test permittivity at higher microwave frequency.

  16. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on tunable functionalized copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede

    2015-01-01

    system, with respect to functionalization, is achieved. It is investigated how the different functionalization variables affect essential DE properties, including dielectric permittivity, dielectric loss, elastic modulus and dielectric breakdown strength, and the optimal degree of chemical......%) was obtained without compromising other vital DE properties such as elastic modulus, gel fraction, dielectric and viscous loss and electrical breakdown strength....

  17. Production of graphite spheres with a high density

    International Nuclear Information System (INIS)

    Tscherry, V.

    1976-01-01

    It is possible to obtain small spheres with a diameter of approximately 1,000 μm with the help of an automated press fitted with a profiled plunger. The spheres consist of graphite and a binder. Depending on the size of the plunger, 1 + 6 Σn (n = 0,1,2,...) spheres of equivalent diameter may be pressed with one stroke of the plunger. The spheres are bound to each other by a thin burr. The green end product is obtained by breaking the sheets of spheres and deburring them. (orig.) [de

  18. The world of Nano

    International Nuclear Information System (INIS)

    Noh, Seung Jeong; Hyun, Jun Won; An, Yong Hyeon; Lee, Sung Uk; Jee, Hye Gu; Kim, Young Seon

    2006-07-01

    The contents of this book are the beginning of nano technology, definition of nano, commercialization of nano technology, prospect of nano technology, survive with nano t-, development strategy of n-t in the U.S, and Japan, Korea, and other countries, comparison of development strategy of n-t among each country, various measurement technology for practical n-t, scanning tunneling microscopy, nano device, carbon nano tube, nano belt and nano wire, application of sensor in daily life, energy, post-Genome period and using as medicine with nano bio technology.

  19. Size characterisation of noble-metal nano-crystals formed in sapphire by ion irradiation and subsequent thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mota-Santiago, Pablo-Ernesto [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico); Crespo-Sosa, Alejandro, E-mail: crespo@fisica.unam.mx [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico); Jimenez-Hernandez, Jose-Luis; Silva-Pereyra, Hector-Gabriel; Reyes-Esqueda, Jorge-Alejandro; Oliver, Alicia [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Systematic study on the formation of Ag and Au nano-particles in Al{sub 2}O{sub 3}. Black-Right-Pointing-Pointer Annealing in a reducing atmosphere, below the metal melting point is more suitable. Black-Right-Pointing-Pointer Au nano-particles grow up to 15 nm and Ag nano-particles up to 45 nm in radius. Black-Right-Pointing-Pointer Ostwald ripening is the mechanism responsible for the formation of large nanoparticles. Black-Right-Pointing-Pointer Optical properties of metallic nano-particles in Al{sub 2}O{sub 3} can be related to their size. - Abstract: Metallic nano-particles embedded in transparent dielectrics are very important for new technological applications because of their unique optical properties. These properties depend strongly on the size and shape of the nano-particles. In order to achieve the synthesis of metallic nano-particles it has been used the technique of ion implantation. This is a very common technique because it allows the control of the depth and concentration of the metallic ions inside the sample, limited mostly by straggling, without introducing other contaminant agents. The purpose of this work was to measure the size of the nano-particles grown under different conditions in Sapphire and its size evolution during the growth process. To achieve this goal, {alpha}-Al{sub 2}O{sub 3} single crystals were implanted with Ag or Au ions at room temperature with different fluences (from 2 Multiplication-Sign 10{sup 16} ions/cm{sup 2} to 8 Multiplication-Sign 10{sup 16} ions/cm{sup 2}). Afterwards, the samples were annealed at different temperatures (from 600 Degree-Sign C to 1100 Degree-Sign C) in oxidising, reducing, Ar or N{sub 2} atmospheres. We measured the ion depth profile by Rutherford Backscattering Spectroscopy (RBS) and the nano-crystals size distribution by using two methods, the surface plasmon resonance in the optical extinction spectrum and the Transmission Electron Microscopy (TEM).

  20. Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method.

    Science.gov (United States)

    Gopi, D; Indira, J; Kavitha, L; Sekar, M; Mudali, U Kamachi

    2012-07-01

    Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Gel-sphere-pac reactor fuel fabrication and its application to a variety of fuels

    International Nuclear Information System (INIS)

    Olsen, A.R.; Judkins, R.R.

    1979-12-01

    The gel-sphere-pac fuel fabrication option was evaluated for its possible application to commercial scale fuel fabrication for 19 fuel element designs that use oxide fuel in metal clad rods. The dry gel spheres are prepared at the reprocessing plant and are then calcined, sintered, inspected, and loaded into fuel rods and packed by low-energy vibration. A fuel smear density of 83 to 88% theoretical can be obtained. All fuel fabrication process steps were defined and evaluated from fuel receiving to finished fuel element shipping. The evaluation also covers the feasibility of the process, the current status of technology, estimates of the required time and cost to develop the technology to commercial status, and the safety and licensability of commercial scale plants. The primary evaluation was for a Light-Water Reactor fuel element containing (U,Pu)O 2 fuel. The other 18 fuel element types - 3 for Light-Water Reactors, 1 for a Heavy-Water Reactor, 1 for a Gas-Cooled Fast Reactor, 7 for Liquid-Metal-Cooled Fast Breeder Reactors, and 3 pairs for Light-Water Prebreeder and Breeder Reactors - were compared with the Light-Water Reactor. The gel-sphere-pac option was found applicable to 17 of the 19 element types; the characteristics of a commercial scale plant were defined for these for making cost estimates for such plants. The evaluation clearly shows the gel-sphere-pac process to be a viable fuel fabrication option. Estimates indicate a significant potential fabrication cost advantage for the gel-sphere-pac process if a remotely operated and remotely maintained fuel fabrication plant is required

  2. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede

    2014-01-01

    Dielectric elastomers (DES) are a promising new transducer technology, but high driving voltages limit their current commercial potential. One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric...

  3. Thorium/uranium mixed oxide nano-crystals: Synthesis, structural characterization and magnetic properties

    International Nuclear Information System (INIS)

    Hudry, Damien; Griveau, Jean-Christophe; Apostolidis, Christos; Colineau, Eric; Rasmussen, Gert; Walter, Olaf; Wang, Di; Venkata Sai Kiran Chakravadhaluna; Courtois, Eglantine; Kubel, Christian

    2014-01-01

    One of the primary aims of the actinide community within nano-science is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects (e.g., nano-crystals) are necessary. Hence, a 'library' dedicated to the preparation of various actinide based nano-scale building blocks is currently being developed. Nano-scale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nano-crystals (both for thorium and uranium, and recently extended to neptunium and plutonium). In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nano-crystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate (together with additional capping agents) into benzyl ether can be used to synthesize thorium/uranium mixed oxide nano-crystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium/uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nano-crystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nano-crystals of non-magnetic oxides as recently claimed in the literature. (authors)

  4. Public libraries, as an infrastructure for a sustainable public sphere: A systematic review of research: A preliminary paper

    DEFF Research Database (Denmark)

    Audunson, Ragnar; Svandhild, Aabø,; Blomgren, Roger

    of the major findings are: Research on libraries as public sphere institutions cover a wide range of topics the dominating being freedom of access to information, often related to social inclusion, empowerment and justice. Contributions are often normative and non-empirical, but the proportion of empirically...... based research is increasing. This paper focuses on contributions related to public libraries.......This paper is based on a systematic literature search aiming at identifying research on the role of libraries as institutions underpinning a sustainable public sphere in a digital age. The major research questions are: 1. Is systematic literature search a fruitful method when it comes to a social...

  5. Enhancement of polarization property of silane-modified BaTiO3 nanoparticles and its effect in increasing dielectric property of epoxy/BaTiO3 nanocomposites

    Directory of Open Access Journals (Sweden)

    Thi Tuyet Mai Phan

    2016-03-01

    Full Text Available The surface modification of synthesized nano-BaTiO3 particles was carried out using γ-aminopropyl trimethoxy silane (γ-APS in an ethanol/water solution. The modified particles were characterized by FTIR, TGA, surface charge analysis, and by dielectric constant measurement. The silane molecules were attached to the surface of BaTiO3 particles through SiOBaTiO3 bonds. The γ-APS grafted on BaTiO3 made the dielectric constant of the particles increase at frequencies ≥0.3 kHz in a wide range of temperature (25 °C–140 °C, due to the presence of NH2 groups. The dependence of the polarization vs. electrical field was measured in order to elucidate the dielectric behavior of the silane treated BaTiO3 in comparison to untreated BaTiO3. The nanocomposite based on epoxy resin containing BaTiO3 nanoparticles untreated and treated with γ-APS was also prepared and characterized. The results indicated that the γ-APS-modified BaTiO3 surfaces significantly enhanced the dielectric property of the nanocomposite.

  6. A comprehensive study of soft magnetic materials based on FeSi spheres and polymeric resin modified by silica nanorods

    International Nuclear Information System (INIS)

    Strečková, M.; Füzer, J.; Kobera, L.; Brus, J.; Fáberová, M.; Bureš, R.; Kollár, P.; Lauda, M.; Medvecký, Ĺ.; Girman, V.; Hadraba, H.; Bat'ková, M.; Bat'ko, I.

    2014-01-01

    A novel soft magnetic composite (SMC) based on spherical FeSi particles precisely covered by hybrid phenolic resin was designed. The hybrid resin including silica nano-rods chemically incorporated into the phenolic polymer matrix was prepared by the modified sol–gel method. A chemical bridge connecting silica nano-rods with the base polymeric net was verified by FTIR, 13 C and 29 Si NMR spectroscopy, whereas the shape and size of silica nano-rods were determined by TEM. It is shown that the modification of polymeric resin by silica nano-rods generally leads to the improved thermal and mechanical properties of the final samples. The hybrid resin serves as a perfect insulating coating deposited on FeSi particles and the core–shell particles can be further compacted by standard powder metallurgy methods in order to prepare final samples for mechanical, electric and magnetic testing. SEM images evidence negligible porosity, uniform distribution of the hybrid resin around FeSi particles, as well as, dimensional shape stability of the final samples after thermal treatment. The hardness, flexural strength and density of the final samples are comparable to the sintered SMCs, but they simultaneously exhibit much higher specific resistivity along with only slightly lower coercivity and permeability. - Highlights: • Soft magnetic composites are designed for electrotechnical applications. • Electroinsulating layer consists of phenolic resin modified with silica nano-rods. • NMR, FTIR and DSC analysis is used to characterize hybrid resin. • Spherical Fe–Si particles covered by hybrid resin form a core–shell composite. • Mechanical, electrical and magnetic properties are described in detail

  7. Evolution of nickel sulfide hollow spheres through topotactic transformation

    Science.gov (United States)

    Wei, Chengzhen; Lu, Qingyi; Sun, Jing; Gao, Feng

    2013-11-01

    In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment.In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment. Electronic supplementary information (ESI) available: XRD patterns; SEM images and TEM images. See DOI: 10.1039/c3nr03371f

  8. Super Dielectric Materials.

    Science.gov (United States)

    Fromille, Samuel; Phillips, Jonathan

    2014-12-22

    Evidence is provided here that a class of materials with dielectric constants greater than 10⁵ at low frequency (dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 10⁸ in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 10⁴. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc. ), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to "short" the individual water droplets. Potentially NPS capacitor stacks can surpass "supercapacitors" in volumetric energy density.

  9. A FEW CONSIDERATIONS REGARDING THE SPHERE OF FINANCIAL RELATIONS

    OpenAIRE

    Bota Anton Florin

    2009-01-01

    The author discusses his financial affairs sphere, looking at this issue under a double aspect: analysis of the financial relations sphere and analyzing the financial activity sphere. Analysis of the financial relations sphere is made on the basis of fou

  10. The Positive Freedom of the Public Sphere

    DEFF Research Database (Denmark)

    Hansen, Ejvind

    2015-01-01

    calls for new reflections on the possible relationship between media, public sphere and democracy. This paper argues that we should change the questions that are raised when we try to assess the public sphere. It is argued that the traditional (Enlightenment) focus upon negative liberties and the truth-value......The relationship between democracy and the media since the appearance of Habermas' major texts in the 1960s has been articulated through theories of the public sphere. The structure of the public sphere is significantly influenced by the communicative media, and the emergence of the internet thus...

  11. Electrical and mechanical properties of 0.5Ba (Zr0.2Ti0.8)O3-0.5 (Ba0.7Ca0.3)TiO3 (BZT-BCT) lead free ferroelectric ceramics reinforced with Al2O3 nano-oxide

    International Nuclear Information System (INIS)

    Adhikari, Prativa; Mazumder, R.

    2014-01-01

    Piezoelectric ceramics are widely used as actuator, resonator, and spark igniter. Recently, much attention has been paid to prepare 0.5Ba (Zr 0.2 Ti 0.8 )O 3 -0.5 (Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) piezoelectric ceramics because of its good dielectric, piezoelectric properties and environment friendly nature. However, piezoelectric ceramics based on BaTiO 3 suffer from low reliability and poor mechanical properties such as strength and toughness. For practical application improvement of the mechanical properties of BaTiO 3 -based ceramics is strongly required. A novel method has been used to improve the mechanical properties of structural ceramics by reinforcement of oxide (Al 2 O 3 , MgO, ZrO 2 and Stabilized-ZrO 2 ) or non-oxide (SiC) particles. It is well known that electrical properties of ferroelectric ceramics generally degrade with non-ferroelectric additives and decrease in sinterability usually encountered with refractory oxide additives. Use of nano-oxide additives may drastically reduce the amount of additive and electrical property may not degrade much. In this report we would show the electrical and mechanical properties of BZT-BCT with Al 2 O 3 nano oxide additive. Modified BZT-BCT nanocomposites were prepared by mixing and sintering of solid state synthesized Zr, Ca modified barium titanate powder and small amount (0.1-2.0 vol %) of nano-oxides, i.e. Al 2 O 3 . Effect of sintering temperature, time, particle size of the nano-oxide additives on electrical (dielectric constant, loss factor, Curie temperature, d 33 ) and mechanical (flexural strength, fracture toughness, hardness) properties were studied. We obtained ∼ 94% dense BZT-BCT reinforced with Al 2 O 3 nano-oxide at 1300℃ without degrading electrical properties (dielectric constant (4850), low dissipation factor (0.0242)) and superior mechanical properties (flexural strength - 60.3 MPa, Vickers hardness-750-800 MPa). (author)

  12. Contemporary dielectric materials

    CERN Document Server

    Saravanan, R

    2016-01-01

    This book deals with experimental results of the physical characterization of several important, dielectric materials of great current interest. The experimental tools used for the analysis of these materials include X-ray diffraction, dielectric measurements, magnetic measurements using a vibrating sample magnetometer, optical measurements using a UV-Visible spectrometer etc.

  13. Spherical Approximation on Unit Sphere

    Directory of Open Access Journals (Sweden)

    Eman Samir Bhaya

    2018-01-01

    Full Text Available In this paper we introduce a Jackson type theorem for functions in LP spaces on sphere And study on best approximation of  functions in  spaces defined on unit sphere. our central problem is to describe the approximation behavior of functions in    spaces for  by modulus of smoothness of functions.

  14. A FEW CONSIDERATIONS REGARDING THE SPHERE OF FINANCIAL RELATIONS

    Directory of Open Access Journals (Sweden)

    Bota Anton Florin

    2009-05-01

    Full Text Available The author discusses his financial affairs sphere, looking at this issue under a double aspect: analysis of the financial relations sphere and analyzing the financial activity sphere. Analysis of the financial relations sphere is made on the basis of fou

  15. TWO FERROMAGNETIC SPHERES IN HOMOGENEOUS MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    Yury A. Krasnitsky

    2018-01-01

    Full Text Available The problem of two spherical conductors is studied quite in detail with bispherical coordinates usage and has numerous appendices in an electrostatics. The boundary-value problem about two ferromagnetic spheres enclosed on homogeneous and infinite environment in which the lack of spheres exists like homogeneous magnetic field is considered. The solution of Laplace's equation in the bispherical system of coordinates allows us to find the potential and field distribution in all spaces, including area between spheres. The boundary conditions in potential continuity and in ordinary density constituent of spheres surfaces induction flux are used. It is supposed that spheres are identical, and magnetic permeability of their material is expressed in  >> 0. The problem about falling of electromagnetic plane wave on the system of two spheres, which possesses electrically small sizes, can be considered as quasistationary. The scalar potentials received as a result of Laplace's equation solution are represented by the series containing Legendre polynomials. The concept of two spheres system effective permeability is introduced. It is equal to the advantage in magnitude of magnetic induction flux vector through a certain system’s section arising due to its magnetic properties. Necessary ratios for the effective permeability referred to the central system’s section are obtained. Particularly, the results can be used during the analysis of ferroxcube core clearance, which influences on the magnetic antenna properties. 

  16. Bioinspiration From Nano to Micro Scales

    CERN Document Server

    2012-01-01

    Methods in bioinspiration and biomimicking have been around for a long time. However, due to current advances in modern physical, biological sciences, and technologies, our understanding of the methods have evolved to a new level. This is due not only to the identification of mysterious and fascinating phenomena but also to the understandings of the correlation between the structural factors and the performance based on the latest theoretical, modeling, and experimental technologies. Bioinspiration: From Nano to Micro Scale provides readers with a broad view of the frontiers of research in the area of bioinspiration from the nano to macroscopic scales, particularly in the areas of biomineralization, antifreeze protein, and antifreeze effect. It also covers such methods as the lotus effect and superhydrophobicity, structural colors in animal kingdom and beyond, as well as behavior in ion channels. A number of international experts in related fields have contributed to this book, which offers a comprehensive an...

  17. Dielectric relaxation of barium strontium titanate and application to thin films for DRAM capacitors

    Science.gov (United States)

    Baniecki, John David

    This thesis examines the issues associated with incorporating the high dielectric constant material Barium Strontium Titanate (BSTO) in to the storage capacitor of a dynamic random access memory (DRAM). The research is focused on two areas: characterizing and understanding the factors that control charge retention in BSTO thin films and modifying the electrical properties using ion implantation. The dielectric relaxation of BSTO thin films deposited by metal-organic chemical vapor deposition (MOCVD) is investigated in the time and frequency domains. It is shown that the frequency dispersion of the complex capacitance of BSTO thin films can be understood in terms of a power-law frequency dependence from 1mHz to 20GHz. From the correspondence between the time and frequency domain measurements, it is concluded that the power-law relaxation currents extend back to the nano second regime of DRAM operation. The temperature, field, and annealing dependence of the dielectric relaxation currents are also investigated and mechanisms for the observed power law relaxation are explored. An equivalent circuit model of a high dielectric constant thin film capacitor is developed based on the electrical measurements and implemented in PSPICE. Excellent agreement is found between the experimental and simulated electrical characteristics showing the utility of the equivalent circuit model in simulating the electrical properties of high dielectric constant thin films. Using the equivalent circuit model, it is shown that the greatest charge loss due to dielectric relaxation occurs during the first read after a refresh time following a write to the opposite logic state for a capacitor that has been written to the same logic state for a long time (opposite state write charge loss). A theoretical closed form expression that is a function of three material parameters is developed which estimates the opposite state write charge loss due to dielectric relaxation. Using the closed form

  18. Spinning the fuzzy sphere

    International Nuclear Information System (INIS)

    Berenstein, David; Dzienkowski, Eric; Lashof-Regas, Robin

    2015-01-01

    We construct various exact analytical solutions of the SO(3) BMN matrix model that correspond to rotating fuzzy spheres and rotating fuzzy tori. These are also solutions of Yang Mills theory compactified on a sphere times time and they are also translationally invariant solutions of the N=1"∗ field theory with a non-trivial charge density. The solutions we construct have a ℤ_N symmetry, where N is the rank of the matrices. After an appropriate ansatz, we reduce the problem to solving a set of polynomial equations in 2N real variables. These equations have a discrete set of solutions for each value of the angular momentum. We study the phase structure of the solutions for various values of N. Also the continuum limit where N→∞, where the problem reduces to finding periodic solutions of a set of coupled differential equations. We also study the topology change transition from the sphere to the torus.

  19. Effects of Surface Roughness and Mechanical Properties of Cover-Layer on Near-Field Optical Recording

    Science.gov (United States)

    Kim, Jin-Hong; Lee, Jun-Seok; Lim, Jungshik; Seo, Jung-Kyo

    2009-03-01

    Narrow gap distance in cover-layer incident near-field recording (NFR) configuration causes a collision problem in the interface between a solid immersion lens and a disk surface. A polymer cover-layer with smooth surface results in a stable gap servo while a nanocomposite cover-layer with high refractive index shows a collision problem during the gap servo test. Even though a dielectric cover-layer, in which the surface is rougher than the polymer, supplements the mechanical properties, an unclear eye pattern due to an unstable gap servo can be obtained after a chemical mechanical polishing. Not only smooth surface but also good mechanical properties of cover-layer are required for the stable gap servo in the NFR.

  20. Ground penetrating radar utilization in exploring inadequate concrete covers in a new bridge deck

    Directory of Open Access Journals (Sweden)

    Md. Istiaque Hasan

    2014-01-01

    Full Text Available The reinforced concrete cast in place four span deck of a concrete bridge near Roanoke, Texas, was recently completed. Due to possible construction errors, it was suspected that the concrete covers in the deck did not conform to drawings and specifications. A full scale non-destructive evaluation of the concrete covers was carried out using ground penetrating radar (GPR equipment. Cover values were determined from the radargram generated from the scan. The estimated covers were plotted on contour maps. Migration data can substitute the drilling based ground truth data without compromising the concrete cover estimations, except for areas with very high cover values. Areas with high water content may result in inaccurate concrete dielectric constants. Based on the results, significant retrofitting of the bridge deck, such as additional overlay, was recommended.

  1. Finding a source inside a sphere

    International Nuclear Information System (INIS)

    Tsitsas, N L; Martin, P A

    2012-01-01

    A sphere excited by an interior point source or a point dipole gives a simplified yet realistic model for studying a variety of applications in medical imaging. We suppose that there is an exterior field (transmission problem) and that the total field on the sphere is known. We give analytical inversion algorithms for determining the interior physical characteristics of the sphere as well as the location, strength and orientation of the source/dipole. We start with static problems (Laplace’s equation) and then proceed to acoustic problems (Helmholtz equation). (paper)

  2. Analysis of transmittance properties in 1D hybrid dielectric photonic crystal containing superconducting thin films

    Science.gov (United States)

    Soltani, Osswa; Zaghdoudi, Jihene; Kanzari, Mounir

    2018-06-01

    By means of two fluid model and transfer matrix method (TMM), we investigate theoretically the transmittance properties of a defective hybrid dielectric-dielectric photonic crystal that contains a superconducting material as a defect layer. The considered hybrid photonic structure is: H(LH) 7(HLSLH) P H(LH) 7 , where H is the high refractive index dielectric, L is the low refractive index dielectric, S is the superconducting material and P is the repetitive number. The results show that the variation of the number and the positions of the transmissions modes depend strongly on the repetitive number P, the temperature T and the thickness of the layer S. An improvement of the spectral response is obtained with the exponential gradation of layer thicknesses dj =d0 + βejα , where d0 is the initial thickness of the layer j, α and β are two particular constants for each material. In addition, the effect of the incident angle for both transverse electric (TE) and transverse magnetic (TM) polarizations on the transmittance spectrum is discussed. As a result, we propose a tunable narrow stop-band polychromatic filter that covers the visible wavelength.

  3. Super Dielectric Materials

    Directory of Open Access Journals (Sweden)

    Samuel Fromille

    2014-12-01

    Full Text Available Evidence is provided here that a class of materials with dielectric constants greater than 105 at low frequency (<10−2 Hz, herein called super dielectric materials (SDM, can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 108 in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 104. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc., filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution, herein called New Paradigm Super (NPS capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to “short” the individual water droplets. Potentially NPS capacitor stacks can surpass “supercapacitors” in volumetric energy density.

  4. Environmental risk assessment of engineered nano-SiO2 , nano iron oxides, nano-CeO2 , nano-Al2 O3 , and quantum dots.

    Science.gov (United States)

    Wang, Yan; Nowack, Bernd

    2018-05-01

    Many research studies have endeavored to investigate the ecotoxicological hazards of engineered nanomaterials (ENMs). However, little is known regarding the actual environmental risks of ENMs, combining both hazard and exposure data. The aim of the present study was to quantify the environmental risks for nano-Al 2 O 3 , nano-SiO 2 , nano iron oxides, nano-CeO 2 , and quantum dots by comparing the predicted environmental concentrations (PECs) with the predicted-no-effect concentrations (PNECs). The PEC values of these 5 ENMs in freshwaters in 2020 for northern Europe and southeastern Europe were taken from a published dynamic probabilistic material flow analysis model. The PNEC values were calculated using probabilistic species sensitivity distribution (SSD). The order of the PNEC values was quantum dots nano-CeO 2  nano iron oxides nano-Al 2 O 3  nano-SiO 2 . The risks posed by these 5 ENMs were demonstrated to be in the reverse order: nano-Al 2 O 3  > nano-SiO 2  > nano iron oxides > nano-CeO 2  > quantum dots. However, all risk characterization values are 4 to 8 orders of magnitude lower than 1, and no risk was therefore predicted for any of the investigated ENMs at the estimated release level in 2020. Compared to static models, the dynamic material flow model allowed us to use PEC values based on a more complex parameterization, considering a dynamic input over time and time-dependent release of ENMs. The probabilistic SSD approach makes it possible to include all available data to estimate hazards of ENMs by considering the whole range of variability between studies and material types. The risk-assessment approach is therefore able to handle the uncertainty and variability associated with the collected data. The results of the present study provide a scientific foundation for risk-based regulatory decisions of the investigated ENMs. Environ Toxicol Chem 2018;37:1387-1395. © 2018 SETAC. © 2018 SETAC.

  5. Terahertz-frequency dielectric response of liquids

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Møller, Uffe; Cooke, David

    The dielectric response of liquids spans many decades in frequency. The dielectric response of a polar liquid is typically determined by relaxational dynamics of the dipolar moments of the liquid. In contrast, the dielectric response of a nonpolar liquid is determined by much weaker collision......-induced dipole moments. In the polar liquid water the fastest relaxational dynamics is found at terahertz frequencies, just below the first intermolecular vibrational and librational modes. In this presentation we will discuss optical terahertz spectroscopic techniques for measurement of the full dielectric...... function of liquids at terahertz frequencies. We will review the current understanding of the high-frequency dielectric spectrum of water, and discuss the relation between the dielectric spectrum and the thermodynamic properties of certain aqueous solutions....

  6. Emulsion-phase synthesis of honeycomb-like Mg{sub 5}(OH){sub 2}(CO{sub 3}){sub 4}.4H{sub 2}O micro-spheres and subsequent decomposition to MgO

    Energy Technology Data Exchange (ETDEWEB)

    Gao Guo, E-mail: gaogaoguoguo@yahoo.com.c [Department of Bio-Nano-Science and Engineering, National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Xiang Lan, E-mail: xianglan@mail.tsinghua.edu.c [Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-04-09

    Herein we report a simple emulsion-phase route for the synthesis of honeycomb-like basic magnesium carbonate (BMC, Mg{sub 5}(OH){sub 2}(CO{sub 3}){sub 4}.4H{sub 2}O) micro-spheres at 80 {sup o}C. Magnesium(II) salts in water are precipitated by sodium carbonate in the presence of cetyltrimethylammonium bromide (CTAB). Scanning electron microscopy shows the obtained BMC samples are composed of a lot of micro-spheres (diameter ranging from 8 to 10 {mu}m) which are interweaved by a lot of nano-sized thin sheets (thickness of 20-30 nm and length >1 {mu}m). The BMC micro-spheres prepared by this approach are porous and appear to be hollow structures. The size and shape of BMC are related to the CTAB concentration and temperature. The lower concentration of CTAB resulted in the decrease of the micro-spheres sizes. When the temperature was elevated to 110 {sup o}C, hexagonal tablets (thickness of 20 nm, length of each side varies from 400 to 600 nm) can be prepared. After the calcinations for BMC at 600 {sup o}C for 2 h, BMC are almost completely converted to MgO. Transmission electron microscopy indicates that the obtained MgO samples have a poly-crystalline feature. The possible formation mechanism of BMC micro-spheres has been discussed.

  7. Nano-scaled hydroxyapatite/silk fibroin sheets support osteogenic differentiation of rat bone marrow mesenchymal cells

    International Nuclear Information System (INIS)

    Tanaka, Toshimitsu; Hirose, Motohiro; Kotobuki, Noriko; Ohgushi, Hajime; Furuzono, Tsutomu; Sato, Junichi

    2007-01-01

    A novel biomaterial that was composed of nano-scaled sintered hydroxyapatite (HAp) and silk fibroin (SF) was fabricated. We cultured rat marrow mesenchymal cells (MMCs) on this biomaterial (nano-HAp/SF sheet), on bare SF sheets, and on tissue culture polystyrene (TCPS) dishes as controls, then evaluated cell adhesion, proliferation, and differentiation of the MMCs. After 1 h of culture, a large number of viable cells were observed on the nano-HAp/SF sheets in comparison to the controls. In addition, after 3 h of culture, the morphology of the cells on the nano-HAp/SF sheets was quite different from that on the SF sheets. MMCs extrude their cytoplasmic processes to nano-HAp particles and are well attached to the sheets. After 14 days of culture, under osteogenic conditions, the alkaline phosphatase (ALP) activity and bone-specific osteocalcin secretion of the cells on nano-HAp/SF sheets were higher than were those on the controls. These results indicated that the surface of the nano-HAp/SF sheets is covered with appropriate HAp crystal for MMC adhesion/proliferation and that the sheets effectively support the osteogenic differentiation of MMCs. Therefore, the nano-HAp/SF sheet is an effective biomaterial that is applicable in bone reconstruction surgery

  8. Chemical Functionalization, Self-Assembly, and Applications of Nano materials and Nano composites 2014

    International Nuclear Information System (INIS)

    Yan, X.; Jiao, T.; Balan, L.; Chen, X.; Hu, M.Z.; Liu, W.

    2014-01-01

    The growing interests in nano materials and nano composites call for the development of processing techniques to obtain multiple functionalization nano structures and achieve the tailoring of specific features of the nanometer size. Functional nano materials and nano composites will expand the applied range of the original material and at the same time promote the development of inter discipline. Thus, the chemical functionalization and bottom-up assemblies of nano materials and subsequent applications will accelerate the development of nano science and nano technology.

  9. Nano forum 2012, VII edition, Rome, 24-26 September 2012

    International Nuclear Information System (INIS)

    Mariani, C.; Rossi, M.; Terranova, M.L.; Vittori Antisari, M.

    2013-01-01

    The intent of this issue of Il Nuovo Cimento Colloquia is to highlight the breadth and range of the research activities that have been presented at Nanoforum 2012 VIII edition held in Rome on September 24-26, 2012. The Nanoforum events are designed to offer a forum for the exchange of information on the latest progress in the exploiting field of nanotechnology. In addition to bringing together researchers involved in diverse R and D activities related to the 'nano' area, Nanoforum also endeavours to gather experts from industry. In doing so, Nanoforum provides a platform for researchers to discover new research opportunities, to identify the requirements for continued advancement in their field and to overcome the technological challenges related to nano materials production and applications. Emphasis is given to monitor progresses, to evaluate tendencies, to present innovative techniques and sophisticated strategies for materials growth and characterization at the nano scale. The papers published in this issue present an overview of some significant aspects of the nano technologies presented at Nanoforum 2012, covering current trends and developments in both basic and applied research. Topics range from the chemistry and physics of the synthesis/manufacturing processes, to characterization methodologies and to the engineering of nano materials for devices and bio-inspired applications. The editors are deeply grateful to all the authors for their inspiring contribution and precious collaboration.

  10. Silicone-based Dielectric Elastomers

    DEFF Research Database (Denmark)

    Skov, Anne Ladegaard

    Efficient conversion of energy from one form to another (transduction) is an important topic in our daily day, and it is a necessity in moving away from the fossil based society. Dielectric elastomers hold great promise as soft transducers, since they are compliant and light-weight amongst many...... energy efficient solutions are highly sought. These properties allow for interesting products ranging very broadly, e.g. from eye implants over artificial skins over soft robotics to huge wave energy harvesting plants. All these products utilize the inherent softness and compliance of the dielectric...... elastomer transducers. The subject of this thesis is improvement of properties of silicone-based dielectric elastomers with special focus on design guides towards electrically, mechanically, and electromechanically reliable elastomers. Strategies for improving dielectric elastomer performance are widely...

  11. IBM WebSphere Application Server 80 Administration Guide

    CERN Document Server

    Robinson, Steve

    2011-01-01

    IBM WebSphere Application Server 8.0 Administration Guide is a highly practical, example-driven tutorial. You will be introduced to WebSphere Application Server 8.0, and guided through configuration, deployment, and tuning for optimum performance. If you are an administrator who wants to get up and running with IBM WebSphere Application Server 8.0, then this book is not to be missed. Experience with WebSphere and Java would be an advantage, but is not essential.

  12. A novel synthesis of micrometer silica hollow sphere

    International Nuclear Information System (INIS)

    Pan Wen; Ye Junwei; Ning Guiling; Lin Yuan; Wang Jing

    2009-01-01

    Silica microcapsules (hollow spheres) were synthesized successfully by a novel CTAB-stabilized water/oil emulsion system mediated hydrothermal method. The addition of urea to a solution of aqueous phase was an essential step of the simple synthetic procedure of silica hollow spheres, which leads to the formation of silica hollow spheres with smooth shell during hydrothermal process. The intact hollow spheres were obtained by washing the as-synthesized solid products with distilled water to remove the organic components. A large amount of silanol groups were retained in the hollow spheres by this facile route without calcination. The morphologies and optical properties of the product were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the silica hollow spheres has been presented

  13. Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

    Directory of Open Access Journals (Sweden)

    Ammar Ben Brahim

    2013-05-01

    Full Text Available This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting.

  14. Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

    Science.gov (United States)

    Ghorbal, Achraf; Grisotto, Federico; Charlier, Julienne; Palacin, Serge; Goyer, Cédric; Demaille, Christophe; Ben Brahim, Ammar

    2013-01-01

    This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM) electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting. PMID:28348337

  15. Unsteady flow over a decelerating rotating sphere

    Science.gov (United States)

    Turkyilmazoglu, M.

    2018-03-01

    Unsteady flow analysis induced by a decelerating rotating sphere is the main concern of this paper. A revolving sphere in a still fluid is supposed to slow down at an angular velocity rate that is inversely proportional to time. The governing partial differential equations of motion are scaled in accordance with the literature, reducing to the well-documented von Kármán equations in the special circumstance near the pole. Both numerical and perturbation approaches are pursued to identify the velocity fields, shear stresses, and suction velocity far above the sphere. It is detected that an induced flow surrounding the sphere acts accordingly to adapt to the motion of the sphere up to some critical unsteadiness parameters at certain latitudes. Afterward, the decay rate of rotation ceases such that the flow at the remaining azimuths starts revolving freely. At a critical unsteadiness parameter corresponding to s = -0.681, the decelerating sphere rotates freely and requires no more torque. At a value of s exactly matching the rotating disk flow at the pole identified in the literature, the entire flow field around the sphere starts revolving faster than the disk itself. Increasing values of -s almost diminish the radial outflow. This results in jet flows in both the latitudinal and meridional directions, concentrated near the wall region. The presented mean flow results will be useful for analyzing the instability features of the flow, whether of a convective or absolute nature.

  16. Reversible thermal gelation in soft spheres

    DEFF Research Database (Denmark)

    Kapnistos, M.; Vlassopoulos, D.; Fytas, G.

    2000-01-01

    Upon heating, concentrated solutions of star polymers and block copolymer micelles in a good solvent, representing soft spheres, undergo a reversible gelation. This phenomenon is attributed to the formation of clusters causing a partial dynamic arrest of the swollen interpenetrating spheres at hi...

  17. Spheres of discharge of springs

    Science.gov (United States)

    Springer, Abraham E.; Stevens, Lawrence E.

    2009-02-01

    Although springs have been recognized as important, rare, and globally threatened ecosystems, there is as yet no consistent and comprehensive classification system or common lexicon for springs. In this paper, 12 spheres of discharge of springs are defined, sketched, displayed with photographs, and described relative to their hydrogeology of occurrence, and the microhabitats and ecosystems they support. A few of the spheres of discharge have been previously recognized and used by hydrogeologists for over 80 years, but others have only recently been defined geomorphologically. A comparison of these spheres of discharge to classification systems for wetlands, groundwater dependent ecosystems, karst hydrogeology, running waters, and other systems is provided. With a common lexicon for springs, hydrogeologists can provide more consistent guidance for springs ecosystem conservation, management, and restoration. As additional comprehensive inventories of the physical, biological, and cultural characteristics are conducted and analyzed, it will eventually be possible to associate spheres of discharge with discrete vegetation and aquatic invertebrate assemblages, and better understand the habitat requirements of rare or unique springs species. Given the elevated productivity and biodiversity of springs, and their highly threatened status, identification of geomorphic similarities among spring types is essential for conservation of these important ecosystems.

  18. Nano-Gap Embedded Plasmonic Gratings for Surface Plasmon Enhanced Fluorescence

    Science.gov (United States)

    Bhatnagar, Kunal; Bok, Sangho; Korampally, Venumadhav; Gangopadhyay, Shubhra

    2012-02-01

    Plasmonic nanostructures have been extensively used in the past few decades for applications in sub-wavelength optics, data storage, optoelectronic circuits, microscopy and bio-photonics. The enhanced electromagnetic field produced at the metal/dielectric interface by the excitation of surface plasmons via incident radiation can be used for signal enhancement in fluorescence and surface enhanced Raman scattering studies. Novel plasmonic structures on the sub wavelength scale have been shown to provide very efficient and extreme light concentration at the nano-scale. The enhanced electric field produced within a few hundred nanometers of these structures can be used to excite fluorophores in the surrounding environment. Fluorescence based bio-detection and bio-imaging are two of the most important tools in the life sciences. Improving the qualities and capabilities of fluorescence based detectors and imaging equipment has been a big challenge to the industry manufacturers. We report the novel fabrication of nano-gap embedded periodic grating substrates on the nanoscale using micro-contact printing and polymethylsilsesquioxane (PMSSQ) polymer. Fluorescence enhancement of up to 118 times was observed with these silver nanostructures in conjugation with Rhodamine-590 fluorescent dye. These substrates are ideal candidates for low-level fluorescence detection and single molecule imaging.

  19. Electrical conduction and dielectric relaxation in p-type PVA/CuI polymer composite

    Directory of Open Access Journals (Sweden)

    M.H. Makled

    2013-11-01

    Full Text Available PVA/CuI polymer composite samples have been prepared and subjected to characterizations using FT-IR spectroscopy, DSC analysis, ac spectroscopy and dc conduction. The FT-IR spectral analysis shows remarkable variation of the absorption peak positions whereas DSC illustrates a little decrease of both glass transition temperature, Tg, and crystallization fraction, χ, with increasing CuI concentration. An increase of dc conductivity for PVA/CuI nano composite by increasing CuI concentration is recoded up to 15 wt%, besides it obeys Arhenuis plot with an activation energy in the range 0.54–1.32 eV. The frequency dependence of ac conductivity showed power law with an exponent 0.33 < s < 0.69 which predicts hopping conduction mechanism. The frequency dependence of both dielectric permittivity and dielectric loss obeys Debye dispersion relations in wide range of temperatures and frequency. Significant values of dipole relaxation time obtained which are thermally activated with activation energies in the range 0.33–0.87 eV. A significant value of hopping distance in the range 3.4–1.2 nm is estimated in agreement with the value of Bohr radius of the exciton.

  20. vSphere high performance cookbook

    CERN Document Server

    Sarkar, Prasenjit

    2013-01-01

    vSphere High Performance Cookbook is written in a practical, helpful style with numerous recipes focusing on answering and providing solutions to common, and not-so common, performance issues and problems.The book is primarily written for technical professionals with system administration skills and some VMware experience who wish to learn about advanced optimization and the configuration features and functions for vSphere 5.1.

  1. Differential Calculus on Quantum Spheres

    OpenAIRE

    Welk, Martin

    1998-01-01

    We study covariant differential calculus on the quantum spheres S_q^2N-1. Two classification results for covariant first order differential calculi are proved. As an important step towards a description of the noncommutative geometry of the quantum spheres, a framework of covariant differential calculus is established, including a particular first order calculus obtained by factorization, higher order calculi and a symmetry concept.

  2. Scattering characteristics of relativistically moving concentrically layered spheres

    Science.gov (United States)

    Garner, Timothy J.; Lakhtakia, Akhlesh; Breakall, James K.; Bohren, Craig F.

    2018-02-01

    The energy extinction cross section of a concentrically layered sphere varies with velocity as the Doppler shift moves the spectral content of the incident signal in the sphere's co-moving inertial reference frame toward or away from resonances of the sphere. Computations for hollow gold nanospheres show that the energy extinction cross section is high when the Doppler shift moves the incident signal's spectral content in the co-moving frame near the wavelength of the sphere's localized surface plasmon resonance. The energy extinction cross section of a three-layer sphere consisting of an olivine-silicate core surrounded by a porous and a magnetite layer, which is used to explain extinction caused by interstellar dust, also depends strongly on velocity. For this sphere, computations show that the energy extinction cross section is high when the Doppler shift moves the spectral content of the incident signal near either of olivine-silicate's two localized surface phonon resonances at 9.7 μm and 18 μm.

  3. Dielectric spectroscopy of PMMA-LiClO4 based polymer electrolyte plasticized with ethylene carbonate EC

    Science.gov (United States)

    Pal, P.; Ghosh, A.

    2018-04-01

    Dielectric spectroscopy covering the frequency range 0.01 Hz - 2 MHz for PMMA-LiClO4 based polymer electrolyte embedded with different concentration of ethylene carbonate (x = 0, 20 and 40 wt%) has been analyzed using Havrilliak-Negami formalism. The reciprocal temperature dependence of inverse relaxation time obtained from the analysis of dielectric spectra follows Vogel-Tammann-Fulcher behaviour. The shape parameters obtained from this analysis change with ethylene carbonate concentrations. From the fits of the experimental result using Kohlrausch-Williams-Watts function. We have obtained stretched exponent β which indicates that the relaxation is highly non-exponential. The decay function obtained from electric modulus data is highly asymmetric.

  4. Instability of extremal relativistic charged spheres

    International Nuclear Information System (INIS)

    Anninos, Peter; Rothman, Tony

    2002-01-01

    With the question 'Can relativistic charged spheres form extremal black holes?' in mind, we investigate the properties of such spheres from a classical point of view. The investigation is carried out numerically by integrating the Oppenheimer-Volkov equation for relativistic charged fluid spheres and finding interior Reissner-Nordstroem solutions for these objects. We consider both constant density and adiabatic equations of state, as well as several possible charge distributions, and examine stability by both a normal mode and an energy analysis. In all cases, the stability limit for these spheres lies between the extremal (Q=M) limit and the black hole limit (R=R + ). That is, we find that charged spheres undergo gravitational collapse before they reach Q=M, suggesting that extremal Reissner-Nordstroem black holes produced by collapse are ruled out. A general proof of this statement would support a strong form of the cosmic censorship hypothesis, excluding not only stable naked singularities, but stable extremal black holes. The numerical results also indicate that although the interior mass-energy m(R) obeys the usual m/R + as Q→M. In the Appendix we also argue that Hawking radiation will not lead to an extremal Reissner-Nordstroem black hole. All our results are consistent with the third law of black hole dynamics, as currently understood

  5. Phylogeography by diffusion on a sphere: whole world phylogeography

    Directory of Open Access Journals (Sweden)

    Remco Bouckaert

    2016-09-01

    Full Text Available Background Techniques for reconstructing geographical history along a phylogeny can answer many questions of interest about the geographical origins of species. Bayesian models based on the assumption that taxa move through a diffusion process have found many applications. However, these methods rely on diffusion processes on a plane, and do not take the spherical nature of our planet in account. Performing an analysis that covers the whole world thus does not take in account the distortions caused by projections like the Mercator projection. Results In this paper, we introduce a Bayesian phylogeographical method based on diffusion on a sphere. When the area where taxa are sampled from is small, a sphere can be approximated by a plane and the model results in the same inferences as with models using diffusion on a plane. For taxa sampled from the whole world, we obtain substantial differences. We present an efficient algorithm for performing inference in a Markov Chain Monte Carlo (MCMC algorithm, and show applications to small and large samples areas. We compare results between planar and spherical diffusion in a simulation study and apply the method by inferring the origin of Hepatitis B based on sequences sampled from Eurasia and Africa. Conclusions We describe a framework for performing phylogeographical inference, which is suitable when the distortion introduced by map projections is large, but works well on a smaller scale as well. The framework allows sampling tips from regions, which is useful when the exact sample location is unknown, and placing prior information on locations of clades in the tree. The method is implemented in the GEO_SPHERE package in BEAST 2, which is open source licensed under LGPL and allows joint tree and geography inference under a wide range of models.

  6. Optics of dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2002-01-01

    From the work carried out within the ph.d. project two topics have been selected for this thesis, namely emission of radiation by sources in dielectric microstructures, and planar photonic crystal waveguides. The work done within the first topic, emission of radiation by sources in dielectric...... microstructures, will be presented in the part I of this thesis consisting of the chapters 2-5. An introductions is given in chapter 2. In part I three methods are presented for calculating spontaneous and classical emission from sources in dielectric microstructures. The first method presented in chapter 3...... is based on the Fermi Golden Rule, and spontaneous emission from emitters in a passive dielectric microstructure is calculated by summing over the emission into each electromagnetic mode of the radiation field. This method is applied to investigate spontaneous emission in a two-dimensional photonic crystal...

  7. Thermal dielectric function

    International Nuclear Information System (INIS)

    Moneta, M.

    1999-01-01

    Thermal dielectric functions ε(k,ω) for homogeneous electron gas were determined and discussed. The ground state of the gas is described by the Fermi-Dirac momentum distribution. The low and high temperature limits of ε(k,ω) were related to the Lindhard dielectric function and to ε(k, omega) derived for Boltzmann and for classical momentum distributions, respectively. (author)

  8. Analysis of photonic band gaps in two-dimensional photonic crystals with rods covered by a thin interfacial layer

    International Nuclear Information System (INIS)

    Trifonov, T.; Marsal, L.F.; Pallares, J.; Rodriguez, A.; Alcubilla, R.

    2004-01-01

    We investigate different aspects of the absolute photonic band gap (PBG) formation in two-dimensional photonic structures consisting of rods covered with a thin dielectric film. Specifically, triangular and honeycomb lattices in both complementary arrangements, i.e., air rods drilled in silicon matrix and silicon rods in air, are studied. We consider that the rods are formed of a dielectric core (silicon or air) surrounded by a cladding layer of silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or germanium (Ge). Such photonic lattices present absolute photonic band gaps, and we study the evolution of these gaps as functions of the cladding material and thickness. Our results show that in the case of air rods in dielectric media the existence of dielectric cladding reduces the absolute gap width and may cause complete closure of the gap if thick layers are considered. For the case of dielectric rods in air, however, the existence of a cladding layer can be advantageous and larger absolute PBG's can be achieved

  9. AIE-doped poly(ionic liquid) photonic spheres: a single sphere-based customizable sensing platform for the discrimination of multi-analytes.

    Science.gov (United States)

    Zhang, Wanlin; Gao, Ning; Cui, Jiecheng; Wang, Chen; Wang, Shiqiang; Zhang, Guanxin; Dong, Xiaobiao; Zhang, Deqing; Li, Guangtao

    2017-09-01

    By simultaneously exploiting the unique properties of ionic liquids and aggregation-induced emission (AIE) luminogens, as well as photonic structures, a novel customizable sensing system for multi-analytes was developed based on a single AIE-doped poly(ionic liquid) photonic sphere. It was found that due to the extraordinary multiple intermolecular interactions involved in the ionic liquid units, one single sphere could differentially interact with broader classes of analytes, thus generating response patterns with remarkable diversity. Moreover, the optical properties of both the AIE luminogen and photonic structure integrated in the poly(ionic liquid) sphere provide multidimensional signal channels for transducing the involved recognition process in a complementary manner and the acquisition of abundant and sufficient sensing information could be easily achieved on only one sphere sensor element. More importantly, the sensing performance of our poly(ionic liquid) photonic sphere is designable and customizable through a simple ion-exchange reaction and target-oriented multi-analyte sensing can be conveniently realized using a selective receptor species, such as counterions, showing great flexibility and extendibility. The power of our single sphere-based customizable sensing system was exemplified by the successful on-demand detection and discrimination of four multi-analyte challenge systems: all 20 natural amino acids, nine important phosphate derivatives, ten metal ions and three pairs of enantiomers. To further demonstrate the potential of our spheres for real-life application, 20 amino acids in human urine and their 26 unprecedented complex mixtures were also discriminated between by the single sphere-based array.

  10. High-pressure cell for simultaneous dielectric and neutron spectroscopy

    Science.gov (United States)

    Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo; Pedersen, Ib H.; Capaccioli, Simone; Adrjanowicz, Karolina; Paluch, Marian; Gonthier, Julien; Frick, Bernhard; Lelièvre-Berna, Eddy; Peters, Judith; Niss, Kristine

    2018-02-01

    In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation and fast vibrations at the same time. The cell, constructed in cylindrical geometry, is made of a high-strength aluminum alloy and operates up to 500 MPa in a temperature range between roughly 2 and 320 K. In order to measure the scattered neutron intensity and the sample capacitance simultaneously, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data on dipropylene glycol, using both backscattering and time-of-flight instruments. We have carried out the experiments at different combinations of temperature and pressure in both the supercooled liquid and glassy state.

  11. Moisture content determination in solid biofuels by dielectric and NIR reflection methods

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Peter Daugbjerg; Morsing, Merete [Department of Forest and Landscape, The Royal Veterinary and Agricultural University, Rolighedsvej 23, DK-1958 Frederiksberg C (Denmark); Hartmann, Hans; Boehm, Thorsten [Technologie- und Foerderzentrum fuer Nachwachsende Rohstoffe (TFZ), Schulgasse 18, D-94315 Straubing (Germany); Temmerman, Michael; Rabier, Fabienne [Departement Genie Rural, Chee de Namur 146, B-5030 Gembloux (Belgium)

    2006-11-15

    One near infrared (NIR) reflectance and five dielectric moisture meters were tested for their capability of measuring moisture content (MC) in solid biofuels. Ninety-eight samples were tested at up to eight moisture levels covering the MC range from fresh fuel to approximately 10% MC (w.b.). The fuel types ranged from typical solid biofuels such as coniferous and deciduous wood chips over short rotation coppice (SRC) to sunflower seed and olive stones. The most promising calibrations were obtained with the NIR reflection method and two dielectric devices where the sample is placed in a container integrated in the device. The calibration equations developed show that there is a profound influence from both laboratory and fuel type. It is suggested that individual calibrations that are based on the specific fuel types used at the individual heating plant could be applied. (author)

  12. Electron current extraction from radio frequency excited micro-dielectric barrier discharges

    International Nuclear Information System (INIS)

    Wang, Jun-Chieh; Kushner, Mark J.; Leoni, Napoleon; Birecki, Henryk; Gila, Omer

    2013-01-01

    Micro dielectric barrier discharges (mDBDs) consist of micro-plasma devices (10–100 μm diameter) in which the electrodes are fully or partially covered by dielectrics, and often operate at atmospheric pressure driven with radio frequency (rf) waveforms. In certain applications, it may be desirable to extract electron current out of the mDBD plasma, which necessitates a third electrode. As a result, the physical structure of the m-DBD and the electron emitting properties of its materials are important to its operation. In this paper, results from a two-dimensional computer simulation of current extraction from mDBDs sustained in atmospheric pressure N 2 will be discussed. The mDBDs are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz. Following avalanche by electron impact ionization in the mDBD cavity, the plasma can be expelled from the cavity towards the extraction electrode during the part of the rf cycle when the extraction electrode appears anodic. The electron current extraction can be enhanced by biasing this electrode. The charge collection can be controlled by choice of rf frequency, rf driving voltage, and permittivity of the dielectric barrier.

  13. The evolution of telemedicine and nano-technology

    Science.gov (United States)

    Park, Dong Kyun; Young Jung, Eun; Chan Moon, Byung

    2012-10-01

    This paper will cover definition and history of telemedicine, changes in medical paradigm and roll of telemedicine and roll of nano-technology for evolution of telemedicine. Hypothetically, telemedicine is distance communication for medical purpose and modern definition explains telemedicine as `a system of health care delivery in which physicians examine distant patients through the use of telecommunications technology. Medical service will change to personalized medicine based on gene information to prevent and manage diseases due to decrease of acute diseases, population aging and increase of prevalence in chronic diseases, which means current medical services based on manualized treatment for diseases will change to personalized medicine based on individual gene information. Also, international healthcare will be activated to provide high quality medical services with low cost using developed transportation. Moreover, hospital centered medical services will change to patients centered medical service due to increase of patient's rights. Development in sensor technology is required for telemedicine to be applied as basic infrastructure for medical services. Various researches in nano-biosensor field are conducted due to introduction of new technologies. However, most researches are in fundamental levels that requires more researches for stability and clinical usefulness. Nano technology is expected to achieve innovative development and define new criteria for disease prevention and management.

  14. Elastic spheres can walk on water.

    Science.gov (United States)

    Belden, Jesse; Hurd, Randy C; Jandron, Michael A; Bower, Allan F; Truscott, Tadd T

    2016-02-04

    Incited by public fascination and engineering application, water-skipping of rigid stones and spheres has received considerable study. While these objects can be coaxed to ricochet, elastic spheres demonstrate superior water-skipping ability, but little is known about the effect of large material compliance on water impact physics. Here we show that upon water impact, very compliant spheres naturally assume a disk-like geometry and dynamic orientation that are favourable for water-skipping. Experiments and numerical modelling reveal that the initial spherical shape evolves as elastic waves propagate through the material. We find that the skipping dynamics are governed by the wave propagation speed and by the ratio of material shear modulus to hydrodynamic pressure. With these insights, we explain why softer spheres skip more easily than stiffer ones. Our results advance understanding of fluid-elastic body interaction during water impact, which could benefit inflatable craft modelling and, more playfully, design of elastic aquatic toys.

  15. Bonner sphere spectrometer for characterization of BNCT beam

    Energy Technology Data Exchange (ETDEWEB)

    Marek, Milan, E-mail: mam@nri.cz [Nuclear Research Institute Rez, Husinec 130, 25068 Husinec-Rez (Czech Republic); Viererbl, Ladislav [Nuclear Research Institute Rez, Husinec 130, 25068 Husinec-Rez (Czech Republic)

    2011-12-15

    The characterization of the epithermal beam is performed by different dosimetry techniques that give information on neutron flux as well as neutron and photon doses. One of the possible methods is based on the measurement of thermal neutrons in a moderation environment, which enables the evaluation of neutron flux in a group structure and also neutron dose. The advantage of such a spectrometer consists of the fact that 90% response intervals of the spheres continuously cover the epithermal part of the neutron energy range. The method has been applied to characterize the epithermal neutron beams at several research centers in USA, Finland, the Netherlands and Czech Republic. The comparison of the MIT FCB, HFR HB11, VTT FiR, and LVR-15 beam parameters is presented in this paper.

  16. Silicon based near infrared photodetector using self-assembled organic crystalline nano-pillars

    Energy Technology Data Exchange (ETDEWEB)

    Ajiki, Yoshiharu, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Micromachine Center, 67 Kanda Sakumagashi, Chiyoda-ku, Tokyo 100-0026 (Japan); Kan, Tetsuo [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Yahiro, Masayuki; Hamada, Akiko; Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Adachi, Junji [Office for Strategic Research Planning, Kyushu University, 6-10-1 Hakozaki, Higashi, Fukuoka 812-8581 (Japan); Matsumoto, Kiyoshi [IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Shimoyama, Isao, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2016-04-11

    We propose a silicon (Si) based near-infrared photodetector using self-assembled organic crystalline nano-pillars, which were formed on an n-type Si substrate and were covered with an Au thin-film. These structures act as antennas for near-infrared light, resulting in an enhancement of the light absorption on the Au film. Because the Schottky junction is formed between the Au/n-type Si, the electron excited by the absorbed light can be detected as photocurrent. The optical measurement revealed that the nano-pillar structures enhanced the responsivity for the near-infrared light by 89 (14.5 mA/W) and 16 (0.433 mA/W) times compared with those of the photodetector without nano-pillars at the wavelengths of 1.2 and 1.3 μm, respectively. Moreover, no polarization dependency of the responsivity was observed, and the acceptable incident angle ranged from 0° to 30°. These broad responses were likely to be due to the organic nano-pillar structures' having variation in their orientation, which is advantageous for near-infrared detector uses.

  17. The element level time domain (ELTD) method for the analysis of nano-optical systems: I. Nondispersive media

    Science.gov (United States)

    Fallahi, Arya; Oswald, Benedikt; Leidenberger, Patrick

    2012-04-01

    We study a 3-dimensional, dual-field, fully explicit method for the solution of Maxwell's equations in the time domain on unstructured, tetrahedral grids. The algorithm uses the element level time domain (ELTD) discretization of the electric and magnetic vector wave equations. In particular, the suitability of the method for the numerical analysis of nanometer structured systems in the optical region of the electromagnetic spectrum is investigated. The details of the theory and its implementation as a computer code are introduced and its convergence behavior as well as conditions for stable time domain integration is examined. Here, we restrict ourselves to non-dispersive dielectric material properties since dielectric dispersion will be treated in a subsequent paper. Analytically solvable problems are analyzed in order to benchmark the method. Eventually, a dielectric microlens is considered to demonstrate the potential of the method. A flexible method of 2nd order accuracy is obtained that is applicable to a wide range of nano-optical configurations and can be a serious competitor to more conventional finite difference time domain schemes which operate only on hexahedral grids. The ELTD scheme can resolve geometries with a wide span of characteristic length scales and with the appropriate level of detail, using small tetrahedra where delicate, physically relevant details must be modeled.

  18. Movements of a Sphere Moving Over Smooth and Rough Inclines

    Science.gov (United States)

    Jan, Chyan-Deng

    1992-01-01

    The steady movements of a sphere over a rough incline in air, and over smooth and rough inclines in a liquid were studied theoretically and experimentally. The principle of energy conservation was used to analyze the translation velocities, rolling resistances, and drag coefficients of a sphere moving over the inclines. The rolling resistance to the movement of a sphere from the rough incline was presumed to be caused by collisions and frictional slidings. A varnished wooden board was placed on the bottom of an experimental tilting flume to form a smooth incline and a layer of spheres identical to the sphere moving over them was placed on the smooth wooden board to form a rough incline. Spheres used in the experiments were glass spheres, steel spheres, and golf balls. Experiments show that a sphere moving over a rough incline with negligible fluid drag in air can reach a constant translation velocity. This constant velocity was found to be proportional to the bed inclination (between 11 ^circ and 21^circ) and the square root of the sphere's diameter, but seemingly independent of the sphere's specific gravity. Two empirical coefficients in the theoretical expression of the sphere's translation velocity were determined by experiments. The collision and friction parts of the shear stress exerted on the interface between the moving sphere and rough incline were determined. The ratio of collision to friction parts appears to increase with increase in the bed inclination. These two parts seem to be of the same order of magnitude. The rolling resistances and the relations between the drag coefficient and Reynolds number for a sphere moving over smooth and rough inclines in a liquid, such as water or salad oil, were determined by a regression analysis based on experimental data. It was found that the drag coefficient for a sphere over the rough incline is larger than that for a sphere over the smooth incline, and both of which are much larger than that for a sphere in free

  19. Application of dielectric surface barrier discharge for food storage

    Directory of Open Access Journals (Sweden)

    Yassine BELLEBNA

    2015-12-01

    Full Text Available Ozone (O3 is a powerful oxidizer and has much higher disinfection potential than chlorine and other disinfectants. Ozone finds its application mainly in water treatment and air purification Dielectric barrier discharge (DBD method has proved to be the best method to produce ozone. Dried air or oxygen is forced to pass through a 1-2 mm gap. The aim of this study was to show that disinfection system using ozone generated by dielectric barrier discharge (DBD is an effective alternative to be used in food industry and ensures a safe quality of air for optimum preservation of fruits and vegetables. The DBDs are specific kind of discharges because one (or sometimes both electrodes is covered by a dielectric material, thereby preventing the discharge to move towards electrical breakdown. A succession of microdischarges occurs rapidly; their "lifetime" is in the range of a few nanoseconds. One of their most important applications is the production of ozone for air treatment, used mainly in the area of food industry, for extending the storage life of foods. After the achievement of a surface DBD reactor of cylindrical shape and its electrical characterization, it was then used as an ozone generator for air disinfection. Obtained results have shown that this reactor used as an ozone generator is effective for disinfection of air by removing viruses, bacteria and pathogens, causing the slowdown of the ripening process of fruits and vegetables.

  20. Formal Variability of Terms in the Sphere of Network Technologies

    Directory of Open Access Journals (Sweden)

    Roman Viktorovich Deniko

    2015-09-01

    Full Text Available The article addresses the problem of formal variability of terms in the sphere of network terminology in the Russian language. The research is based on data from the Internet communication in the sphere of network technologies. Such formal variability types as graphical, phonemic, word building and complex (graphic and phonetic, morphologic and accentual are discussed in this article. The authors reveal the reasons for graphic variability of foreign origin terms making up the international terminological fund. These reasons cover such aspects as the use of graphics of source language and recipient language; the presence or absence of hyphenation, etc. It is determined that the phonemic variants of terms appear as a result of oral or written borrowings. The existence of such variants is also connected with the stage of their adaptation in the Russian language after borrowing. In this case the variants are related with soft or hard pronunciation of consonants. There are also some cases of phonemic variability on the graphic level. The complex variability is regarded as a part of active processes taking place in the modern Russian language, and these processes involve both native and foreign origin terms. The particular attention is paid to the word-building variants – word-building affixes the variability of which is peculiar of network technologies. The results of the research show that the variability of professional units belonging to the network technologies sublanguage is caused by the active process of borrowing of specialpurpose vocabulary into the Russian language. The process is due to the intensification of intercultural communication in the professional spheres.

  1. Thermal conductivities for sintered and sphere-pac Li2O and γ-LiAlO2 solid breeders with and without irradiation effects

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tam, S.W.

    1984-07-01

    Thermal conductivities (k, k/sub eff/) have been estimated for sintered and sphere-pac Li 2 O and γ-LiAlO 2 with and without neutron irradiation effects. The estimation is based on (1) data from unirradiated UO 2 , Li 2 O, and γ-LiAlO 2 ; (2) data from irradiated dielectric insulator materials; and (3) relatively simple physical models. Comparison of model predictions with limited ex- and in-reactor data found reasonable agreement, thus lending credence for their use in design applications. The impact of thermal conductivities on tritium breeding and power generation in fusion solid-breeder blankets is briefly highlighted

  2. Electric dipoles on the Bloch sphere

    OpenAIRE

    Vutha, Amar C.

    2014-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.

  3. Effect of dielectric barrier discharge treatment on surface nanostructure and wettability of polylactic acid (PLA) nonwoven fabrics

    Science.gov (United States)

    Ren, Yu; Xu, Lin; Wang, Chunxia; Wang, Xiaona; Ding, Zhirong; Chen, Yuyue

    2017-12-01

    Polylactic acid (PLA) nonwoven fabrics are treated with atmospheric dielectric barrier discharge (DBD) plasma to improve surface wettability. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that micro- to nano-scale textures appear on the treated PLA surfaces dependent on the treatment time. X-ray photoelectron spectroscopy (XPS) analysis reveals that the DBD plasma treatments result in decreased carbon contents and increased oxygen contents as well as slightly increased nitrogen contents. The water contact angle decreases sharply with the increase of the DBD plasma treatment time. The super hydrophilic PLA surfaces (the water contact angle reached 0°) are obtained when the treatment time is longer than 90 s. Ninety days after the DBD plasma treatment, the XPS analysis shows that Csbnd O/Csbnd N and Cdbnd O/Osbnd Cdbnd O percentages decline for all treatment groups. However, the water contact angle is kept constant at 0° for the groups treated above 90 s, which could be due to the oxidized nano-structured layer on the DBD plasma treated PLA surfaces.

  4. Photonic jet μ-etching: from static to dynamic process

    Science.gov (United States)

    Abdurrochman, A.; Lecler, S.; Zelgowski, J.; Mermet, F.; Fontaine, J.; Tumbelaka, B. Y.

    2017-05-01

    Photonic jet etching is a direct-laser etching method applying photonic jet phenomenon to concentrate the laser beam onto the proceeded material. We call photonic jet the phenomenon of the localized sub-wavelength propagative beam generated at the shadow-side surfaces of micro-scale dielectric cylinders or spheres, when they are illuminated by an electromagnetic plane-wave or laser beam. This concentration has made possible the laser to yield sub-μ etching marks, despite the laser was a near-infrared with nano-second pulses sources. We will present these achievements from the beginning when some spherical glasses were used for static etching to dynamic etching using an optical fiber with a semi-elliptical tip.

  5. Structure and performance of dielectric films based on self-assembled nanocrystals with a high dielectric constant.

    Science.gov (United States)

    Huang, Limin; Liu, Shuangyi; Van Tassell, Barry J; Liu, Xiaohua; Byro, Andrew; Zhang, Henan; Leland, Eli S; Akins, Daniel L; Steingart, Daniel A; Li, Jackie; O'Brien, Stephen

    2013-10-18

    Self-assembled films built from nanoparticles with a high dielectric constant are attractive as a foundation for new dielectric media with increased efficiency and range of operation, due to the ability to exploit nanofabrication techniques and emergent electrical properties originating from the nanoscale. However, because the building block is a discrete one-dimensional unit, it becomes a challenge to capture potential enhancements in dielectric performance in two or three dimensions, frequently due to surface effects or the presence of discontinuities. This is a recurring theme in nanoparticle film technology when applied to the realm of thin film semiconductor and device electronics. We present the use of chemically synthesized (Ba,Sr)TiO3 nanocrystals, and a novel deposition-polymerization technique, as a means to fabricate the dielectric layer. The effective dielectric constant of the film is tunable according to nanoparticle size, and effective film dielectric constants of up to 34 are enabled. Wide area and multilayer dielectrics of up to 8 cm(2) and 190 nF are reported, for which the building block is an 8 nm nanocrystal. We describe models for assessing dielectric performance, and distinct methods for improving the dielectric constant of a nanocrystal thin film. The approach relies on evaporatively driven assembly of perovskite nanocrystals with uniform size distributions in a tunable 7-30 nm size range, coupled with the use of low molecular weight monomer/polymer precursor chemistry that can infiltrate the porous nanocrystal thin film network post assembly. The intercrystal void space (low k dielectric volume fraction) is minimized, while simultaneously promoting intercrystal connectivity and maximizing volume fraction of the high k dielectric component. Furfuryl alcohol, which has good affinity to the surface of (Ba,Sr)TiO3 nanocrystals and miscibility with a range of solvents, is demonstrated to be ideal for the production of nanocomposites. The

  6. Human postprandial gastric emptying of 1-3-millimeter spheres

    International Nuclear Information System (INIS)

    Meyer, J.H.; Elashoff, J.; Porter-Fink, V.; Dressman, J.; Amidon, G.L.

    1988-01-01

    Microspheres of pancreatin should empty from the stomachs of patients with pancreatic insufficiency as fast as food. The present study was undertaken in 26 healthy subjects to identify the size of spheres that would empty from the stomach with food and to determine whether different meals alter this size. Spheres of predefined sizes were labeled with /sup 113m/In or /sup 99m/Tc. Using a gamma-camera, we studied the concurrent gastric emptying of spheres labeled with /sup 113m/In and of chicken liver labeled with /sup 99m/Tc in 100-g, 154-kcal or 420-g, 919-kcal meals, or the concurrent emptying of 1-mm vs. larger spheres. One-millimeter spheres emptied consistently (p less than 0.01, paired t-test) faster than 2.4- or 3.2-mm spheres when ingested together with either the 420- or 100-g meals. Thus, in the 1-3-mm range of diameters, sphere size was a more important determinant of sphere emptying than meal size. Statistical analyses indicated that spheres 1.4 +/- 0.3 mm in diameter with a density of 1 empty at the same rate as /sup 99m/Tc-liver. Our data indicate some commercially marketed microspheres of pancreatin will empty too slowly to be effective in digestion of food

  7. Human postprandial gastric emptying of 1-3-millimeter spheres

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.H.; Elashoff, J.; Porter-Fink, V.; Dressman, J.; Amidon, G.L.

    1988-06-01

    Microspheres of pancreatin should empty from the stomachs of patients with pancreatic insufficiency as fast as food. The present study was undertaken in 26 healthy subjects to identify the size of spheres that would empty from the stomach with food and to determine whether different meals alter this size. Spheres of predefined sizes were labeled with /sup 113m/In or /sup 99m/Tc. Using a gamma-camera, we studied the concurrent gastric emptying of spheres labeled with /sup 113m/In and of chicken liver labeled with /sup 99m/Tc in 100-g, 154-kcal or 420-g, 919-kcal meals, or the concurrent emptying of 1-mm vs. larger spheres. One-millimeter spheres emptied consistently (p less than 0.01, paired t-test) faster than 2.4- or 3.2-mm spheres when ingested together with either the 420- or 100-g meals. Thus, in the 1-3-mm range of diameters, sphere size was a more important determinant of sphere emptying than meal size. Statistical analyses indicated that spheres 1.4 +/- 0.3 mm in diameter with a density of 1 empty at the same rate as /sup 99m/Tc-liver. Our data indicate some commercially marketed microspheres of pancreatin will empty too slowly to be effective in digestion of food.

  8. Optically-Induced Magnetic Response in All-Dielectric Nanodisk Composite Structures

    Science.gov (United States)

    Chong, Katie Eve

    Optical technologies developed throughout history have been exploiting the electric response in matters in order to control light. However, little has been explored for the magnetic response in matter at optical frequencies due to the lack of magnetic materials in this spectral region. Recently, specially engineered materials, namely metamaterials, have been developed to exploit the magnetic responses in matter for light manipulation. In particular, researchers have made use of the optically-induced magnetic responses (OIMRs) generated in metallic nanostructures to achieve optical effects not seen in nature. Such magnetic responses serve as a second channel to control light, providing an alternative and an addition to the electric responses and leading to novel observations and innovative ideas for light manipulation. This creates many opportunities for the development of the next generation nano-optics and nanophotonic devices. Dielectric nanostructures have recently been discovered to also support OIMR, which is useful for applications requiring low loss and simpler fabrication procedures, such as wavefront control and robust nanoscale sensing. In this thesis, I present the study of OIMR in several all-dielectric systems based on silicon nanodisks, namely single, clusters and regular arrays of nanodisks. The study of these systems provides knowledge for and insight into harnessing the OIMRs in dielectric nanostructures for future applications. Chapter 1 provides a comprehensive introduction to OIMR by presenting a historic overview of the topic and the basic concepts involved for high-index dielectric particles. This is followed by a description of the pioneer works on OIMR in dielectric spherical nanoparticles, including the Mie theory and its recent experimental verification. The similarities and differences between the properties of plasmonic and dielectric nanostructures in the context of metamaterials are also described and explained. Finally, the motivation

  9. Electric dipoles on the Bloch sphere

    International Nuclear Information System (INIS)

    Vutha, Amar C

    2015-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic and molecular physics. (paper)

  10. Troubleshooting vSphere storage

    CERN Document Server

    Preston, Mike

    2013-01-01

    This is a step-by-step example-oriented tutorial aimed at showing the reader how to troubleshoot a variety of vSphere storage problems, and providing the reader with solutions that can be completed with minimal effort and time in order to limit damage to work.If you are a vSphere administrator, this is the book for you. This book will provide you with 'need to know' information about the various storage transports that ESXi utilizes, the tools and techniques we can use to identify problems, and the fundamental knowledge and steps to take to troubleshoot storage-related issues. Prior knowledge

  11. Single-layer graphene-assembled 3D porous carbon composites with PVA and Fe₃O₄ nano-fillers: an interface-mediated superior dielectric and EMI shielding performance.

    Science.gov (United States)

    Rao, B V Bhaskara; Yadav, Prasad; Aepuru, Radhamanohar; Panda, H S; Ogale, Satishchandra; Kale, S N

    2015-07-28

    In this study, a novel composite of Fe3O4 nanofiller-decorated single-layer graphene-assembled porous carbon (SLGAPC) with polyvinyl alcohol (PVA) having flexibility and a density of 0.75 g cm(-3) is explored for its dielectric and electromagnetic interference (EMI) response properties. The composite is prepared by the solution casting method and its constituents are optimized as 15 wt% SLGAPC and 20 wt% Fe3O4 through a novel solvent relaxation nuclear magnetic resonance experiment. The PVA-SLGAPC-Fe3O4 composite shows high dielectric permittivity in the range of 1 Hz-10 MHz, enhanced by a factor of 4 as compared to that of the PVA-SLGAPC composite, with a reduced loss by a factor of 2. The temperature dependent dielectric properties reveal the activation energy behaviour with reference to the glass transition temperature (80 °C) of PVA. The dielectric hysteresis with the temperature cycle reveals a remnant polarization. The enhanced dielectric properties are suggested to be the result of improvement in the localized polarization of the integrated interface system (Maxwell-Wagner-Sillars (MWS) polarization) formed by the uniform adsorption of Fe3O4 on the surface of SLGAPC conjugated with PVA. The EMI shielding property of the composite with a low thickness of 0.3 mm in the X-band (8.2-12.4 GHz) shows a very impressive shielding efficiency of ∼15 dB and a specific shielding effectiveness of 20 dB (g cm(-3))(-1), indicating the promising character of this material for flexible EMI shielding applications.

  12. Nano-bio-sensing

    CERN Document Server

    Carrara, Sandro

    2011-01-01

    This book examines state-of-the-art applications of nano-bio-sensing. It brings together researchers from nano-electronics and bio-technology, providing multidisciplinary content from nano-structures fabrication to bio-sensing applications.

  13. The Separate Spheres Model of Gendered Inequality.

    Science.gov (United States)

    Miller, Andrea L; Borgida, Eugene

    2016-01-01

    Research on role congruity theory and descriptive and prescriptive stereotypes has established that when men and women violate gender stereotypes by crossing spheres, with women pursuing career success and men contributing to domestic labor, they face backlash and economic penalties. Less is known, however, about the types of individuals who are most likely to engage in these forms of discrimination and the types of situations in which this is most likely to occur. We propose that psychological research will benefit from supplementing existing research approaches with an individual differences model of support for separate spheres for men and women. This model allows psychologists to examine individual differences in support for separate spheres as they interact with situational and contextual forces. The separate spheres ideology (SSI) has existed as a cultural idea for many years but has not been operationalized or modeled in social psychology. The Separate Spheres Model presents the SSI as a new psychological construct characterized by individual differences and a motivated system-justifying function, operationalizes the ideology with a new scale measure, and models the ideology as a predictor of some important gendered outcomes in society. As a first step toward developing the Separate Spheres Model, we develop a new measure of individuals' endorsement of the SSI and demonstrate its reliability, convergent validity, and incremental predictive validity. We provide support for the novel hypotheses that the SSI predicts attitudes regarding workplace flexibility accommodations, income distribution within families between male and female partners, distribution of labor between work and family spheres, and discriminatory workplace behaviors. Finally, we provide experimental support for the hypothesis that the SSI is a motivated, system-justifying ideology.

  14. The Separate Spheres Model of Gendered Inequality.

    Directory of Open Access Journals (Sweden)

    Andrea L Miller

    Full Text Available Research on role congruity theory and descriptive and prescriptive stereotypes has established that when men and women violate gender stereotypes by crossing spheres, with women pursuing career success and men contributing to domestic labor, they face backlash and economic penalties. Less is known, however, about the types of individuals who are most likely to engage in these forms of discrimination and the types of situations in which this is most likely to occur. We propose that psychological research will benefit from supplementing existing research approaches with an individual differences model of support for separate spheres for men and women. This model allows psychologists to examine individual differences in support for separate spheres as they interact with situational and contextual forces. The separate spheres ideology (SSI has existed as a cultural idea for many years but has not been operationalized or modeled in social psychology. The Separate Spheres Model presents the SSI as a new psychological construct characterized by individual differences and a motivated system-justifying function, operationalizes the ideology with a new scale measure, and models the ideology as a predictor of some important gendered outcomes in society. As a first step toward developing the Separate Spheres Model, we develop a new measure of individuals' endorsement of the SSI and demonstrate its reliability, convergent validity, and incremental predictive validity. We provide support for the novel hypotheses that the SSI predicts attitudes regarding workplace flexibility accommodations, income distribution within families between male and female partners, distribution of labor between work and family spheres, and discriminatory workplace behaviors. Finally, we provide experimental support for the hypothesis that the SSI is a motivated, system-justifying ideology.

  15. The Separate Spheres Model of Gendered Inequality

    Science.gov (United States)

    Miller, Andrea L.; Borgida, Eugene

    2016-01-01

    Research on role congruity theory and descriptive and prescriptive stereotypes has established that when men and women violate gender stereotypes by crossing spheres, with women pursuing career success and men contributing to domestic labor, they face backlash and economic penalties. Less is known, however, about the types of individuals who are most likely to engage in these forms of discrimination and the types of situations in which this is most likely to occur. We propose that psychological research will benefit from supplementing existing research approaches with an individual differences model of support for separate spheres for men and women. This model allows psychologists to examine individual differences in support for separate spheres as they interact with situational and contextual forces. The separate spheres ideology (SSI) has existed as a cultural idea for many years but has not been operationalized or modeled in social psychology. The Separate Spheres Model presents the SSI as a new psychological construct characterized by individual differences and a motivated system-justifying function, operationalizes the ideology with a new scale measure, and models the ideology as a predictor of some important gendered outcomes in society. As a first step toward developing the Separate Spheres Model, we develop a new measure of individuals’ endorsement of the SSI and demonstrate its reliability, convergent validity, and incremental predictive validity. We provide support for the novel hypotheses that the SSI predicts attitudes regarding workplace flexibility accommodations, income distribution within families between male and female partners, distribution of labor between work and family spheres, and discriminatory workplace behaviors. Finally, we provide experimental support for the hypothesis that the SSI is a motivated, system-justifying ideology. PMID:26800454

  16. Ni hollow spheres as catalysts for methanol and ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Changwei [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Hu, Yonghong; Rong, Jianhua; Liu, Yingliang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2007-08-15

    In this paper, we successfully synthesized Ni hollow spheres consisting of needle-like nickel particles by using silica spheres as template with gold nanoparticles seeding method. The Ni hollow spheres are applied to methanol and ethanol electrooxidation in alkaline media. The results show that the Ni hollow spheres give a very high activity for alcohol electrooxidation at a very low nickel loading of 0.10 mg cm{sup -2}. The current on Ni hollow spheres is much higher than that on Ni particles. The onset potential and peak potential on Ni hollow spheres are more negative than that on Ni particles for methanol and ethanol electrooxidation. The Ni hollow spheres may be of great potential in alcohol sensor and direct alcohol fuel cells. (author)

  17. VMware vSphere 5.5 cookbook

    CERN Document Server

    G B, Abhilash

    2015-01-01

    This is an excellent handbook for system administrators, support professionals, or for anyone intending to give themselves a headstart in learning how to install, configure, and manage a vSphere environment. It is also a good task-oriented reference guide for consultants or infrastructure architects who design and deploy vSphere environments.

  18. Recent development of antifouling polymers: structure, evaluation, and biomedical applications in nano/micro-structures.

    Science.gov (United States)

    Liu, Lingyun; Li, Wenchen; Liu, Qingsheng

    2014-01-01

    Antifouling polymers have been proven to be vital to many biomedical applications such as medical implants, drug delivery, and biosensing. This review covers the major development of antifouling polymers in the last 2 decades, including the material chemistry, structural factors important to antifouling properties, and how to challenge or evaluate the antifouling performances. We then discuss the applications of antifouling polymers in nano/micro-biomedical applications in the form of nanoparticles, thin coatings for medical devices (e.g., artificial joint, catheter, wound dressing), and nano/microscale fibers. © 2014 Wiley Periodicals, Inc.

  19. Light in complex dielectrics

    NARCIS (Netherlands)

    Schuurmans, F.J.P.

    1999-01-01

    In this thesis the properties of light in complex dielectrics are described, with the two general topics of "modification of spontaneous emission" and "Anderson localization of light". The first part focuses on the spontaneous emission rate of an excited atom in a dielectric host with variable

  20. Acoustic levitation of a large solid sphere

    International Nuclear Information System (INIS)

    Andrade, Marco A. B.; Bernassau, Anne L.; Adamowski, Julio C.

    2016-01-01

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.