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Sample records for film ceria-bismuth bilayer

  1. High performance ceria-bismuth bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) fabricated by combining co-pressing with drop-coating

    KAUST Repository

    Hou, Jie

    2015-03-24

    The Sm0.075Nd0.075Ce0.85O2-δ-Er0.4Bi1.6O3 bilayer structure film, which showed an encouraging performance in LT-SOFCs, was successfully fabricated by a simple low cost technique combining one-step co-pressing with drop-coating.

  2. Fabrication of oriented wrinkles on polydopamine/polystyrene bilayer films.

    Science.gov (United States)

    Wang, Rong; Long, Yuhua; Zhu, Tang; Guo, Jing; Cai, Chao; Zhao, Ning; Xu, Jian

    2017-07-15

    Wrinkles exist widely in nature and our life. In this paper, wrinkles on polydopamine (PDA)/polystyrene (PS) bilayer films were formed by thermal annealing due to the different thermal coefficients of expansion of each layer. The factors that influenced the dimensions of wrinkles were studied. We found that oriented wrinkles could be formed if the bilayer films were patterned with micro-grooves, and the degree of the orientation depended on the thickness of the PDA and the dimensions of the grooves. Combined with the strong adhesion, biocompatibility and reactivity of PDA, the oriented wrinkles on PDA/PS patterned bilayers may find potential application in diffraction gratings, optical sensors and microfluidic devices. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Oxygen diffusion in bilayer polymer films

    DEFF Research Database (Denmark)

    Poulsen, Lars; Zebger, Ingo; Tofte, Jannik Pentti

    2004-01-01

    through the film of poly(ethylene-co-norbornene) and into the polystyrene film was monitored using the phosphorescence of singlet oxygen as a spectroscopic probe. To analyze the data, it was necessary to solve Fick's second law of diffusion for both polymer films. Tractable analytical and numerical...

  4. Study of annealing effects in Al–Sb bilayer thin films

    Indian Academy of Sciences (India)

    Abstract. In this paper, we present preparation and characterization of Al–Sb bilayer thin films. Thin films of thicknesses, 3000/1000 Ц and 3000/1500 Е, were obtained by the thermal evaporation (resistive heating) method. Vacuum annealing and rapid thermal annealing methods were used to mix bilayer thin film structure.

  5. Inverse bilayer magnetoelectric thin film sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yarar, E.; Piorra, A.; Quandt, E., E-mail: eq@tf.uni-kiel.de [Chair for Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany); Salzer, S.; Höft, M.; Knöchel, R. [Microwave Laboratory, Institute of Electrical and Information Engineering, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany); Hrkac, V.; Kienle, L. [Chair for Synthesis and Real Structure, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany)

    2016-07-11

    Prior investigations on magnetoelectric (ME) thin film sensors using amorphous FeCoSiB as a magnetostrictive layer and AlN as a piezoelectric layer revealed a limit of detection (LOD) in the range of a few pT/Hz{sup 1/2} in the mechanical resonance. These sensors are comprised of a Si/SiO{sub 2}/Pt/AlN/FeCoSiB layer stack, as dictated by the temperatures required for the deposition of the layers. A low temperature deposition route of very high quality AlN allows the reversal of the deposition sequence, thus allowing the amorphous FeCoSiB to be deposited on the very smooth Si substrate. As a consequence, the LOD could be enhanced by almost an order of magnitude reaching 400 fT/Hz{sup 1/2} at the mechanical resonance of the sensor. Giant ME coefficients (α{sub ME}) as high as 5 kV/cm Oe were measured. Transmission electron microscopy investigations revealed highly c-axis oriented growth of the AlN starting from the Pt-AlN interface with local epitaxy.

  6. Wetting - Dewetting Transitions of Au/Ni Bilayer Films

    Science.gov (United States)

    Cen, Xi

    Thin films deposited at low temperatures are often kinetically constrained and will dewet the underlying substrate when annealed. Solid state dewetting is driven by the minimization of the total free energy of thin film-substrate interface and free surface, and mostly occurs through surface diffusion. Dewetting is a serious concern in microelectronics reliability. However, it can also be utilized for the self-assembly of nanostructures with potentials in storage, catalysis, or transistors. Therefore, a fundamental understanding of the dewetting behavior of thin metal films is critical for improving the thermal stability of microelectronics and controlling the order of self-assembled nanostructures. Mechanisms for dewetting of single layer films have been studied extensively. However little work has been reported on multilayer or alloyed thin films. In the thesis, the solid state dewetting of Au/Ni bilayer films deposited on SiO2/Si substrates was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and aberration corrected scanning TEM (STEM). Ex-situ SEM and TEM studies were performed with in-situ TEM heating characterization to identify the mechanisms during the dewetting process of Au/Ni bilayer films. The solid state dewetting of Au/Ni bilayer films from SiO2/Si substrates exhibits both homogeneous and localized dewetting of Ni and long-edge retraction for Au under isothermal annealing condition. The top Au layer retracts up to 1 mm from the edge of the substrate wafer to reduce the energetically unfavored Au/Ni interface. In contrast, Ni dewets and agglomerates locally due to its limited diffusivity compared to Au. Film morphology and local chemical composition varies significantly across hundreds of microns along the direction normal to the retracting edge. Besides long range edge receding, localized dewetting shows significant changes in film morphology and chemical distribution. Both Au and Ni shows texturing. Despite

  7. Biomimetic Cationic Nanoparticles Based on Silica: Optimizing Bilayer Deposition from Lipid Films

    Directory of Open Access Journals (Sweden)

    Rodrigo T. Ribeiro

    2017-10-01

    Full Text Available The optimization of bilayer coverage on particles is important for a variety of biomedical applications, such as drug, vaccine, and genetic material delivery. This work aims at optimizing the deposition of cationic bilayers on silica over a range of experimental conditions for the intervening medium and two different assemblies for the cationic lipid, namely, lipid films or pre-formed lipid bilayer fragments. The lipid adsorption on silica in situ over a range of added lipid concentrations was determined from elemental analysis of carbon, hydrogen, and nitrogen and related to the colloidal stability, sizing, zeta potential, and polydispersity of the silica/lipid nanoparticles. Superior bilayer deposition took place from lipid films, whereas adsorption from pre-formed bilayer fragments yielded limiting adsorption below the levels expected for bilayer adsorption.

  8. Development and characterization of novel antimicrobial bilayer films based on Polylactic acid (PLA)/Pickering emulsions.

    Science.gov (United States)

    Zhu, Jun-You; Tang, Chuan-He; Yin, Shou-Wei; Yang, Xiao-Quan

    2018-02-01

    Biodegradable food packaging is sustainable and has a great application prospect. PLA is a promising alternative for petroleum-derived polymers. However, PLA packaging suffers from poor barrier properties compared with petroleum-derived ones. To address this issue, we designed bilayer films based on PLA and Pickering emulsions. The formed bilayer films were compact and uniform and double layers were combined firmly. This strategy enhanced mechanical resistance, ductility and moisture barrier of Pickering emulsion films, and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings in Pickering emulsion layer endowed them with antimicrobial and antioxidant activity. The release profile of thymol was well fitted with Fick's second law. The antimicrobial activity of the films depended on film types, and Pickering emulsion layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer architecture creating synergism of each layer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Study of annealing effects in Al–Sb bilayer thin films

    Indian Academy of Sciences (India)

    Keywords. AlSb; thin film; RBS; optical band gap. Abstract. In this paper, we present preparation and characterization of Al–Sb bilayer thin films. Thin films of thicknesses, 3000/1000 Å and 3000/1500 Å, were obtained by the thermal evaporation (resistive heating) method. Vacuum annealing and rapid thermal annealing ...

  10. Precise Actuation of Bilayer Photomechanical Films Coated with Molecular Azobenzene Chromophores.

    Science.gov (United States)

    Liu, Ziyi; Tang, Rong; Xu, Dandan; Liu, Jian; Yu, Haifeng

    2015-06-01

    Bilayer photomechanical films are fabricated by depositing one layer of molecular azobenzene chromophores onto flexible low-density polyethylene substrates. The photoinduced bending and unbending behavior of five azobenzene derivatives including azobenzene, 4-hydroxy-azobenzene, 4-((4-hydroxyphenyl)diazenyl)bezoitrile, 4-((4-methoxyph-enyl)diazenyl)phenol, and 4-(phenyldiazenyl)phenol is systematically studied by considering the incident light intensity and the thickness of the coated chromophore layers. Precise control of photoinduced curling of the bilayer film is successfully achieved upon irradiation with two beams of UV light, and the curled films can be recovered by thermal relaxation in the dark. The easily fabricated bilayer films show fast photomechanical response, strong photoinduced stress, and stability similar to crosslinked polymeric films. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Electrochemomechanical Behaviour of Bilayer and Trilayer Films with PEDOT and PPY Conducting Polymers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Careem, M.A.; Skaarup, Steen

    2008-01-01

    A detailed study on bilayer and trilayer films prepared with polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers is reported. Both polymers are doped with dodecyl benzenesulfonate (DBS) anions. These multi layer films were prepared electrochemically so that the PEDOT...

  12. Spin glass transition in a thin-film NiO/permalloy bilayer

    Science.gov (United States)

    Ma, Tianyu; Urazhdin, Sergei

    2018-02-01

    We experimentally study magnetization aging in a thin-film NiO/permalloy bilayer. Aging characteristics are nearly independent of temperature below the exchange bias blocking temperature TB, but rapidly vary above it. The dependence on the magnetic history qualitatively changes across TB. The observed behaviors are consistent with the spin glass transition at TB, with significant implications for magnetism and magnetoelectronic phenomena in antiferromagnet/ferromagnet bilayers.

  13. Toroidal hollow-core microcavities produced by self-rolling of strained polymer bilayer films

    Science.gov (United States)

    Luchnikov, V.; Kumar, K.; Stamm, M.

    2008-03-01

    Hollow-core toroidal micro-cavities are obtained by self-rolling of double-layer (polyvinyl pyridine/polystyrole) polymer films. Rolling of the bilayer is due to preferential swelling of polyvinyl pyridine in water solution of dodecyl benzene sulfonic acid. The tube formation proceeds from a circular opening in the film made by photolithography or by mechanical scratching. Toroid equilibrium dimensions are determined by the balance of the elastic energy relaxation via the film scrolling and the work of the in-plane stretching that is due to increasing radius of the toroid. The principle features of the micro-toroid formation process are captured by a simple analytical model. The inner walls of the cavities can be made metal coated. For this aim, the polymer bilayer can be metallized by vacuum sputtering prior to lithographic patterning and rolling of the bilayer. The toroids with metallic inner surfaces are promising for the future research as IR-frequency range resonators.

  14. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yiqin [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Min; Tao, Lei; Wang, Wei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Bai, Peiwen [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  15. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    International Nuclear Information System (INIS)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-01-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  16. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  17. Microstructure and mechanical behavior of a shape memory Ni-Ti bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud, E-mail: nili@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Ivanisenko, Julia [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Schwaiger, Ruth [Karlsruhe Institute of Technology, Institute for Applied Materials, 76021 Karlsruhe (Germany); Hahn, Horst; Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-29

    Two different single-layers and a bi-layer Ni-Ti thin films with chemical compositions of Ni{sub 45}Ti{sub 50}Cu{sub 5}, Ni{sub 50.8}Ti{sub 49.2} and Ni{sub 50.8}Ti{sub 49.2}/Ni{sub 45}Ti{sub 50}Cu{sub 5} (numbers indicate at.%) determined by energy dispersive X-ray spectroscopy were deposited on Si (111) substrates using DC magnetron sputtering. The structures, surface morphology and transformation temperatures of annealed thin films at 500 °C for 15 min and 1 h were studied using grazing incidence X-ray diffraction, transmission electron microscopy (TEM), atomic force microscopy and differential scanning calorimetry (DSC), respectively. Nanoindentation was used to characterize the mechanical properties. The DSC and X-ray diffraction results indicated the austenitic structure of the Ni{sub 50.8}Ti{sub 49.2} and martensitic structure of the Ni{sub 45}Ti{sub 50}Cu{sub 5} thin films while the bi-layer was composed of austenitic and martensitic thin films. TEM study revealed that copper encourages crystallization in the bi-layer such that crystal structure containing nano-precipitates in the Ni{sub 45}Ti{sub 50}Cu{sub 5} layer was detected after 15 min annealing while the Ni{sub 50.8}Ti{sub 49.2} layer crystallized after 60 min at 500 °C. Furthermore, after annealing at 500 °C for 15 min, a precipitate free zone and thin layer amorphous were observed closely to the interface in the top layer. The bi-layer was completely crystallized at 500 °C for 1 h and the orientation of the Ni-rich precipitates indicated a stress gradient in the bi-layer. The bi-layer thin film showed different transformation temperatures and mechanical behavior from the single-layers. The developed bi-layer has different phase transformation temperatures, the higher temperatures of shape memory effect and lower temperature of pseudo-elastic behavior compared to the single-layers. Also, the bi-layer thin film exhibited a combined pseudo-elastic behavior and shape memory effect with a reduced

  18. Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

    Directory of Open Access Journals (Sweden)

    Li Yuan

    2013-09-01

    Full Text Available The coupling effects in bilayer thick metal (silver films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique. Many interesting light phenomena are observed as the distance between the metal rectangular nanohole arrays varies. Coupling effects are found to play very important roles on the optical and electronic properties of bilayer metal rectangular nanohole arrays: antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole, are probably excited in each layer of bilayer metal rectangular nanohole arrays; antisymmetric and symmetric magnetic coupling probably occur between the metal rectangular nanohole arrays.

  19. X-Ray Diffraction Study of Plasma Exposed and Annealed AlSb Bilayer Thin Film

    International Nuclear Information System (INIS)

    Kareem, T. Abdul; Kaliani, A. Anu

    2013-01-01

    Aluminum antimony seems to be a promising semiconducting material for high temperature applications, especially for transistors and P-N junction diodes. Additionally, it is a highly efficient solar material. This paper discusses the plasma induced bilayer diffusion of AlSb bilayer thin films using X-ray diffractogram. AlSb bilayer thin films were prepared on a glass substrate by vacuum evaporation technique. The effect of plasma exposure time and annealing temperature on the micro-structural parameters were investigated. X-ray diffraction studies show that the cubic crystals of Al orient along the (111) plane and the hexagonal crystals of Sb orient along the (003) plane. Newly formed cubic crystals of AlSb are oriented along the (200) plane and they are formed due to the simultaneous growth of Al and Sb crystals during plasma exposure. (plasma technology)

  20. Study of Sb/SnO2 bi-layer films prepared by ion beam sputtering deposition technique

    International Nuclear Information System (INIS)

    Wang, Chun-Min; Huang, Chun-Chieh; Kuo, Jui-Chao; Huang, Jow-Lay

    2014-01-01

    In the present work, bi-layer thin films of Sb/SnO 2 were produced on unheated glass substrates using ion beam sputtering (IBS) technique without post annealing treatment. The thickness of Sb layers was varied from 2 to 10 nm and the Sb layers were deposited on SnO 2 layers having thicknesses of 40 nm to 115 nm. The effect of thickness was studied on the morphological, electrical and optical properties. The Sb/SnO 2 bi-layer resulted in lowering the electrical resistivity as well as reducing the optical transmittance. However, the optical and electrical properties of the bi-layer films were mainly influenced by the thickness of Sb layers due to progressive transfer in structures from aggregate to continuous films. The bi-layer films show the electrical resistivity of 1.4 × 10 −3 Ω cm and an optical transmittance of 26% for Sb film having 10 nm thickness. - Highlights: • Bi-layer Sb/SnO 2 structures were synthesized by ion beam sputtering (IBS) technique. • The 6 nm-thick Sb film is a transition region in this study. • The conductivity of the bi-layer films is increased as Sb thickness increases. • The transmittance of the bi-layer films is decreased as Sb thickness increases

  1. Study of annealing effects in Al–Sb bilayer thin films

    Indian Academy of Sciences (India)

    Study of annealing effects in Al–Sb bilayer thin films. R K MANGAL†, B TRIPATHI, M SINGH and Y K VIJAY*. Department of Physics, University of Rajasthan, Jaipur 302 004, India. †Jaipur Engineering College and Research Centre, Jaipur 303 905, India. MS received 1 August 2006; revised 14 November 2006. Abstract.

  2. Study of annealing effects in In–Sb bilayer thin films

    Indian Academy of Sciences (India)

    TECS

    torr. The optical transmission spectra of as deposited and annealed films have been carried out at room temperature. The variation in optical band gap with thickness was also observed. Rutherford back scattering and X-ray diffraction analysis confirms mixing of bilayer system. The transverse I–V characteristic shows mixing ...

  3. Enhanced Piezoelectric Energy Harvesting Performance of Flexible PVDF-TrFE Bilayer Films with Graphene Oxide.

    Science.gov (United States)

    Bhavanasi, Venkateswarlu; Kumar, Vipin; Parida, Kaushik; Wang, Jiangxin; Lee, Pooi See

    2016-01-13

    Ferroelectric materials have attracted interest in recent years due to their application in energy harvesting owing to its piezoelectric nature. Ferroelectric polymers are flexible and can sustain larger strains compared to inorganic counterparts, making them attractive for harvesting energy from mechanical vibrations. Herein, we report, for the first time, the enhanced piezoelectric energy harvesting performance of the bilayer films of poled poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] and graphene oxide (GO). The bilayer film exhibits superior energy harvesting performance with a voltage output of 4 V and power output of 4.41 μWcm(-2) compared to poled PVDF-TrFE films alone (voltage output of 1.9 V and power output of 1.77 μWcm(-2)). The enhanced voltage and power output in the presence of GO film is due to the combined effect of electrostatic contribution from graphene oxide, residual tensile stress, enhanced Young's modulus of the bilayer films, and the presence of space charge at the interface of the PVDF-TrFE and GO films, arising from the uncompensated polarization of PVDF-TrFE. Higher Young's modulus and dielectric constant of GO led to the efficient transfer of mechanical and electrical energy.

  4. Bilayer formation in thin films of a binary solution

    International Nuclear Information System (INIS)

    Govor, L.V.; Reiter, G.; Bauer, G.H.; Parisi, J.

    2006-01-01

    We consider the formation of a pattern of micrometer-size droplets formed by phase separation in a binary solution composed of a nitrocellulose (NC) solution in amyl acetate and a hexadecylamine (HDA) solution in hexane. Spreading of this solution on a water surface leads to the formation of a bilayer with a top HDA and a lower NC solution layer. The formation of the bilayer was confirmed via spin-coating a similar binary solution on a Si substrate and an HDA solution in hexane on a NC/Si substrate. The subsequent evaporation of the solvents from both layers gives rise to a fast thickness decrease of the top HDA solution layer that decomposes into droplets. The discretely developing increase of the thickness of the HDA droplets can be explained only with the formation of HDA micelles in solution during solvent evaporation

  5. Bilayer formation in thin films of a binary solution

    Science.gov (United States)

    Govor, L. V.; Reiter, G.; Bauer, G. H.; Parisi, J.

    2006-04-01

    We consider the formation of a pattern of micrometer-size droplets formed by phase separation in a binary solution composed of a nitrocellulose (NC) solution in amyl acetate and a hexadecylamine (HDA) solution in hexane. Spreading of this solution on a water surface leads to the formation of a bilayer with a top HDA and a lower NC solution layer. The formation of the bilayer was confirmed via spin-coating a similar binary solution on a Si substrate and an HDA solution in hexane on a NC/Si substrate. The subsequent evaporation of the solvents from both layers gives rise to a fast thickness decrease of the top HDA solution layer that decomposes into droplets. The discretely developing increase of the thickness of the HDA droplets can be explained only with the formation of HDA micelles in solution during solvent evaporation.

  6. Bilayer formation in thin films of a binary solution

    Energy Technology Data Exchange (ETDEWEB)

    Govor, L.V. [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)]. E-mail: leonid.govor@uni-oldenburg.de; Reiter, G. [Institut de Chimie des Surfaces et Interfaces, CNRS-UHA, F-8057 Mulhouse cedex (France); Bauer, G.H. [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany); Parisi, J. [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)

    2006-04-24

    We consider the formation of a pattern of micrometer-size droplets formed by phase separation in a binary solution composed of a nitrocellulose (NC) solution in amyl acetate and a hexadecylamine (HDA) solution in hexane. Spreading of this solution on a water surface leads to the formation of a bilayer with a top HDA and a lower NC solution layer. The formation of the bilayer was confirmed via spin-coating a similar binary solution on a Si substrate and an HDA solution in hexane on a NC/Si substrate. The subsequent evaporation of the solvents from both layers gives rise to a fast thickness decrease of the top HDA solution layer that decomposes into droplets. The discretely developing increase of the thickness of the HDA droplets can be explained only with the formation of HDA micelles in solution during solvent evaporation.

  7. Two Distinct Phases of Bilayer Graphene Films on Ru(0001)

    OpenAIRE

    Papagno M.; Pacilé D.; Topwal D.; Moras P.; Sheverdyaeva P. M.; Natterer F. D.; Lehnert A.; Rusponi S.; Dubout Q.; Calleja F.; Frantzeskakis E.; Pons S.; Fujii J.; Vobornik I.; Grioni M.

    2012-01-01

    By combining angle-resolved photoemission spectroscopy and scanning tunneling microscopy we reveal the structural and electronic properties of multilayer graphene on Ru(0001). We prove that large ethylene exposure allows the synthesis of two distinct phases of bilayer graphene with different properties. The first phase has Bernal AB stacking with respect to the first graphene layer and displays weak vertical interaction and electron doping. The longrange ordered moiré pattern modulates the cr...

  8. High power density thin film SOFCs with YSZ/GDC bilayer electrolyte

    International Nuclear Information System (INIS)

    Cho, Sungmee; Kim, YoungNam; Kim, Jung-Hyun; Manthiram, Arumugam; Wang Haiyan

    2011-01-01

    Graphical abstract: . A: Cross-sectional TEM images show a GDC single layer and YSZ/GDC bilayer electrolyte structures. As clearly observed from TEM images, the YSZ interlayer thickness varies from ∼330 nm to ∼1 μm. B: The cell with the bilayer electrolyte (YSZ ∼330 nm) doubles the overall power output at 750 deg. C compared to that achieved in the GDC single layer cell. Display Omitted Highlights: → YSZ/ GDC bilayer thin film electrolytes were deposited by a pulsed laser deposition (PLD) technique. → Thin YSZ film as a blocking layer effectively suppresses the cell voltage drop without reducing the ionic conductivity of the electrolyte layer. → The YSZ/ GDC bilayer structure presents a feasible architecture for enhancing the overall power density and enabling chemical, mechanical, and structural stability in the cells. - Abstract: Bilayer electrolytes composed of a gadolinium-doped CeO 2 (GDC) layer (∼6 μm thickness) and an yttria-stabilized ZrO 2 (YSZ) layer with various thicknesses (∼330 nm, ∼440 nm, and ∼1 μm) were deposited by a pulsed laser deposition (PLD) technique for thin film solid oxide fuel cells (TFSOFCs). The bilayer electrolytes were prepared between a NiO-YSZ (60:40 wt.% with 7.5 wt.% carbon) anode and La 0.5 Sr 0.5 CoO 3 -Ce 0.9 Gd 0.1 O 1.95 (50:50 wt.%) composite cathode for anode-supported single cells. Significantly enhanced maximum power density was achieved, i.e., a maximum power density of 188, 430, and 587 mW cm -2 was measured in a bilayer electrolyte single cell with ∼330 nm thin YSZ at 650, 700, and 750 deg. C, respectively. The cell with the bilayer electrolyte (YSZ ∼330 nm) doubles the overall power output at 750 deg. C compared to that achieved in the GDC single layer cell. This signifies that the YSZ thin film serves as a blocking layer for preventing electrical current leakage in the GDC layer and also provides chemical, mechanical, and structural integrity in the cell, which leads to the overall enhanced

  9. Magnetic and exchange bias properties of YCo thin films and IrMn/YCo bilayers

    Science.gov (United States)

    Venkat Narayana, M.; Manivel Raja, M.; Jammalamadaka, S. Narayana

    2018-02-01

    We report on the structural and magnetic properties of YCo thin films and IrMn/YCo bilayers. X-ray diffraction infer that all the films are amorphous in nature. Magnetization versus magnetic field measurements reveal room temperature soft ferromagnetism in all the YCo films. Thin films which were grown at 100 W sputter power with growth rates of 0.677, 0.694 and 0.711 Å/sec show better morphology and composition than 50 W (0.333, 0.444 and 0.277 Å/sec) grown films. Perpendicular exchange bias in as deposited bilayers is evident for IrMn/YCo bilayers. Exchange bias (EB) decreases in case of in plane measurements and enhances for out of plane measurements after perpendicular field annealing. EB is more in case of out of plane direction due to large perpendicular anisotropy in comparison with in plane direction. Above the critical thickness, EB variation is explained on the basis of random field model in the Heisenberg regime, which has been proposed by Malozemoff. Indeed there exists an inverse relationship between EB and IrMn layer thickness. Evidenced vertical shift apart from the horizontal shift for magnetization loops is attributed to frozen magnetic moments in one of the layers at the interface. Present results would prove to be helpful in spintronic device applications.

  10. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam, E-mail: mmohri@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-15

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.

  11. Increased drug load and polymer compatibility of bilayered orodispersible films

    NARCIS (Netherlands)

    Visser, J. Carolina; Weggemans, Oekie A. F.; Boosman, Rene J.; Loos, Katja U.; Frijlink, Henderik W.; Woerdenbag, Herman J.

    2017-01-01

    The addition of enalapril maleate to a casting solution for orodispersible films (ODFs) containing hypromellose and carbomer 974P as film forming agents (standard casting solution, SCS) caused a dose dependent reduction of the viscosity. This phenomenon was a serious problem in the preparation of

  12. Hysteresis phenomena in permalloy–niobium bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Uspenskaya, L.S., E-mail: uspenska@issp.ac.ru; Egorov, S.V.

    2014-02-15

    Kinetics of magnetization reversal is studied in bilayer permalloy–niobium hybrid nanofilms by means of a magneto-optic visualization technique. The Nb-sublayer is found to affect the width of magnetic domain walls, the type of the walls, the orientation of the walls, and the kinetics of magnetization reversal in permalloy. Moreover, the low temperature magnetization reversal dependence upon the high temperature prehistory is revealed for a permalloy layer with domain walls of Bloch type. The niobium retains the information about a magnetic pattern freezed in permalloy and causes its reproduction during magnetization reversal. The “memory” is intact under magnetic field cycling as well as under a current flow. The effect demonstrates the efficiency of magnetic pinning and opens a new method for reversible variation of electromagnetic properties of hybrid devices.

  13. Two distinct phases of bilayer graphene films on Ru(0001).

    Science.gov (United States)

    Papagno, Marco; Pacilé, Daniela; Topwal, Dinesh; Moras, Paolo; Sheverdyaeva, Polina Makarovna; Natterer, Fabian Donat; Lehnert, Anne; Rusponi, Stefano; Dubout, Quentin; Calleja, Fabian; Frantzeskakis, Emmanouil; Pons, Stéphane; Fujii, Jun; Vobornik, Ivana; Grioni, Marco; Carbone, Carlo; Brune, Harald

    2012-10-23

    By combining angle-resolved photoemission spectroscopy and scanning tunneling microscopy we reveal the structural and electronic properties of multilayer graphene on Ru(0001). We prove that large ethylene exposure allows the synthesis of two distinct phases of bilayer graphene with different properties. The first phase has Bernal AB stacking with respect to the first graphene layer and displays weak vertical interaction and electron doping. The long-range ordered moiré pattern modulates the crystal potential and induces replicas of the Dirac cone and minigaps. The second phase has an AA stacking sequence with respect to the first layer and displays weak structural and electronic modulation and p-doping. The linearly dispersing Dirac state reveals the nearly freestanding character of this novel second-layer phase.

  14. Effect of annealing on magnetic exchange coupling in CoPt/Co bilayer thin films

    International Nuclear Information System (INIS)

    Kim, J.; Barmak, K.; De Graef, M.; Lewis, L. H.; Crew, D. C.

    2000-01-01

    Thin film CoPt/Co bilayers have been prepared as a model system to investigate the relationship between microstructure and exchange coupling in two-phase nanocomposite permanent magnets. The bilayers were prepared by magnetron sputter deposition of near-equiatomic CoPt with a thickness of 25 nm onto oxidized Si wafers. In the as-deposited state, CoPt had the A1 (fcc) structure and was magnetically soft. Before reinsertion into the sputtering chamber for the deposition of 2.8-16.7 nm thick Co layers, the CoPt films were annealed at 700 degree sign C for 120 min to produce the magnetically hard, fully ordered L1 0 phase. The presence of exchange coupling in the bilayers was verified by magnetic hysteresis and recoil measurements and showed that only for Co thicknesses below 6.3 nm was this layer (in its as-deposited state) coupled through its full thickness to the CoPt layer. Annealing the bilayer samples at 300 and 550 degree sign C for 20 min resulted in improvement of the interlayer magnetic coupling and produced clear differences in the magnetic reversal coherency and the recoil curves. However, for some samples, the improved coupling resulted in a decrease in coercivity, indicating that there is an optimum in the coupling strength for the attainment of high coercivity. Transmission electron microscopy studies of the bilayers in plan view showed that the increased interlayer coupling with annealing was a result of improved granular epitaxy of Co to CoPt. (c) 2000 American Institute of Physics

  15. Water-enhanced adhesion at interface in immiscible bilayer film of polystyrene and poly(methyl methacrylate)

    International Nuclear Information System (INIS)

    Harada, M; Koga, T; Fukumori, K; Sugiyama, J; Geue, T

    2014-01-01

    From nano-scratch tests, strong interfacial adhesion has been found for polystyrene (PS) and poly(methyl methacrylate) (PMMA) bilayer films prepared by a water floating (WF) method, while a PS layer on a PMMA film produced by a spin coating (SC) method peels off easily at the interface. Neutron reflectivity measurements demonstrated a clear difference in the interfacial width (σ) between the two bilayers; σ = 9 nm for the film obtained by the WF method, whereas σ = 5 nm for that by the SC method. Plasticization of the films by water would be responsible for broadening of the interface to enhance adhesion strength.

  16. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-10-09

    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  17. SnO2/TiO2 bilayer thin films exhibiting superhydrophilic properties

    Science.gov (United States)

    Talinungsang, Nibedita Paul; Purkayastha, Debarun Dhar

    2017-05-01

    Nanostructured thin films of TiO2, SnO2, and SnO2/TiO2 have been deposited by sol-gel method. The films are characterized by X-ray diffraction, wettability and optical properties. In the present work, we have achieved a way of converting hydrophilic to super-hydrophilic state by incorporating TiO2 buffer layer in between substrate and SnO2 film, which has its utility in anti-fogging surfaces. The decrease in contact angle of water over SnO2/TiO2 bilayer is attributed to the increase in roughness of the film as well as surface energy of the substrate.

  18. Cross-sectional characterization of the dewetting of a Au/Ni bilayer film

    Energy Technology Data Exchange (ETDEWEB)

    Cen, Xi; Thron, Andrew M.; Zhang, Xinming; Benthem, Klaus van

    2017-07-15

    The solid state dewetting of Au/Ni bilayer films was investigated by cross-sectional transmission electron microscopy techniques, including energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy and precession electron diffraction. After annealing under high vacuum conditions the early stage of film agglomeration revealed significant changes in film morphology and chemical distribution. Both Au and Ni showed texturing. Despite the initial deposition sequence of the as-deposited Au/Ni/SiO{sub 2}/Si interface structure, the majority of the metal/SiO{sub 2} interface was Au/SiO{sub 2} after annealing at 675 °C for 1 h. Void nucleation was predominantly observed at Au/Ni/SiO{sub 2} triple junctions, rather than grain boundary grooving at free surface of the metal film. Detailed cross-sectional characterization reveals that the Au/Ni interface in addition to small amounts of metal alloying strongly affects film break-up and agglomeration kinetics. The formation of Au/SiO{sub 2} interface sections is found to be energetically preferred over Ni/SiO{sub 2} due to compressive stress in the as-deposited Ni layer. Void nucleation is observed at the film/substrate interface, while the formation of voids at Ni/Au phase boundaries inside the metal film is caused by the Kirkendall effect. - Highlights: • The dewetting of Au/Ni bilayer films was studied by cross-sectional TEM techniques. • The majority of the metal/SiO{sub 2} interface was comprised of Au/SiO{sub 2} after annealing. • Void formation was dominant for hole nucleation at early dewetting stage. • The Kirkendall effect was also observed to cause the formation of voids.

  19. Thickness dependencies of structural and magnetic properties of cubic and tetragonal Heusler alloy bilayer films

    Science.gov (United States)

    Ranjbar, R.; Suzuki, K. Z.; Sugihara, A.; Ando, Y.; Miyazaki, T.; Mizukami, S.

    2017-07-01

    The thickness dependencies of the structural and magnetic properties for bilayers of cubic Co-based Heusler alloys (CCHAs: Co2FeAl (CFA), Co2FeSi (CFS), Co2MnAl (CMA), and Co2MnSi (CMS)) and D022-MnGa were investigated. Epitaxy of the B2 structure of CCHAs on a MnGa film was achieved; the smallest thickness with the B2 structure was found for 3-nm-thick CMS and CFS. The interfacial exchange coupling (Jex) was antiferromagnetic (AFM) for all of the CCHAs/MnGa bilayers except for unannealed CFA/MnGa samples. A critical thickness (tcrit) at which perpendicular magnetization appears of approximately 4-10 nm for the CMA/MnGa and CMS/MnGa bilayers was observed, whereas this thickness was 1-3 nm for the CFA/MnGa and CFS/MnGa films. The critical thickness for different CCHAs materials is discussed in terms of saturation magnetization (Ms) and the Jex .

  20. Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

    Directory of Open Access Journals (Sweden)

    Ana Rešček

    2015-12-01

    Full Text Available This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such materials was studied. The results show that, in comparison to the neat PE and PE/PCL films, some of PE/PCL bilayer films with additives exhibit improved barrier properties i.e. decreased water vapour permeability. Higher thermal stability of modified PE/PCL material is obtained due to a modified mechanism of thermal degradation. The samples with the additive nanoparticles homogeneously dispersed in the polymer matrix showed good mechanical properties. Addition of higher ZnO content contributes to the enhanced antibacterial activity of a material.

  1. Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics

    KAUST Repository

    Alshammari, Fwzah Hamud

    2016-08-24

    We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm2 V-1 s-1, but increased to 13.3 cm2 V-1 s-1 using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance. © 2016 American Chemical Society.

  2. Bi-layer sandwich film for antibacterial catheters.

    Science.gov (United States)

    Franz, Gerhard; Schamberger, Florian; Zare, Hamideh Heidari; Bröskamp, Sara Felicitas; Jocham, Dieter

    2017-01-01

    Background: Approximately one quarter of all nosocomial infections can be attributed to the urinary tract. The infections are supposed to be mainly caused by implantations of urethral catheters and stents. A new catheter design is introduced with the aim to lower the high number of nosocomial urethral infections. In order to avoid limitations to use, the design is first applied to conventional commercially available balloon catheters. Results: The main feature of the design is a sandwich layer on both sides of the catheter wall, which is composed of a fragmented base layer of silver capped by a thin film of poly( p -xylylene). This top layer is mainly designed to release a controlled amount of Ag + ions, which is bactericidal, but not toxic to humans. Simultaneously, the lifetime is prolonged to at least one year. The base layer is electrolessly deposited applying Tollens' reagens, the cap layer is deposited by using chemical vapor deposition. Conclusion: The three main problems of this process, electroless deposition of a fragmented silver film on the surface of an electrically insulating organic polymer, irreproducible evaporation during heating of the precursor, and exponential decrease of the layer thickness along the capillary, have been solved trough the application of a simple electrochemical reaction and two standard principles of physics: Papin's pot and the principle of Le Chatelier.

  3. Bi-layer sandwich film for antibacterial catheters

    Directory of Open Access Journals (Sweden)

    Gerhard Franz

    2017-09-01

    Full Text Available Background: Approximately one quarter of all nosocomial infections can be attributed to the urinary tract. The infections are supposed to be mainly caused by implantations of urethral catheters and stents. A new catheter design is introduced with the aim to lower the high number of nosocomial urethral infections. In order to avoid limitations to use, the design is first applied to conventional commercially available balloon catheters.Results: The main feature of the design is a sandwich layer on both sides of the catheter wall, which is composed of a fragmented base layer of silver capped by a thin film of poly(p-xylylene. This top layer is mainly designed to release a controlled amount of Ag+ ions, which is bactericidal, but not toxic to humans. Simultaneously, the lifetime is prolonged to at least one year. The base layer is electrolessly deposited applying Tollens’ reagens, the cap layer is deposited by using chemical vapor deposition.Conclusion: The three main problems of this process, electroless deposition of a fragmented silver film on the surface of an electrically insulating organic polymer, irreproducible evaporation during heating of the precursor, and exponential decrease of the layer thickness along the capillary, have been solved trough the application of a simple electrochemical reaction and two standard principles of physics: Papin’s pot and the principle of Le Chatelier.

  4. Magnetoresistance and magnetostriction of Ni81Fe19 and Co90Fe10 mono- and bilayer films

    International Nuclear Information System (INIS)

    Sahingoz, R.; Hollingworth, M.P.; Gibbs, M.R.J.; Murdoch, S.J.

    2005-01-01

    Monolayer and bilayer films of Ni 81 Fe 19 , Co 90 Fe 10 , Co 90 Fe 10 /Ni 81 Fe 19 , and Ni 81 Fe 19 /Co 90 Fe 10 have been grown on thermally oxidized Si. The magnetoresistance (MR) of the samples was measured as a function of applied DC magnetic field, using a four-point probe method. The magnetostriction constant, λ s , was derived from the change of anisotropy field as a function of strain. The dependence of the MR on different combinations of film layers was investigated. The magnetoresistance of the bilayers changed dramatically upon reversal of the layer order. The mono- and bilayer samples with the same material on top of the substrate showed similar MR loop shapes. However, the saturation fields of the bilayers were larger than those for the monolayers. The magnetostriction of all samples was negative. We discuss the consequences for the study and optimization of spin-valve devices

  5. Study on calcination of bi-layered films produced by anodizing iron in dimethyl sulfoxide electrolyte

    International Nuclear Information System (INIS)

    Jagminas, Arūnas; Klimas, Vaclovas; Mažeika, Kęstutis; Mickevičius, Sigitas; Balakauskas, Saulius

    2012-01-01

    Research on well adherent, thick and nanoporous oxide film formation onto the metal substrates underwent a major burst throughout the last decade. In the current study, thick bi-layered films produced onto a pure iron surface by anodizing way in dimethyl sulfoxide (DMSO) electrolyte containing silica hexafluoride acid have been investigated upon the annealing in air. Compositional, phase and structural transformations of the film material to hematite, α-Fe 2 O 3 , were studied using Mössbauer spectroscopy at room to cryogenic temperatures, thermogravimetry (TG), differential thermal analysis (DTA), photoemission spectroscopy, scanning electron microscopy (SEM), and wave dispersive X-ray spectroscopy (WDX). Experimental findings indicated that much longer heating in air is required for these films to be fully transformed to hematite. This effect is linked here with the complex nature of DMSO films. Based on the combined WDX, photoemission and Mössbauer spectroscopy results, the transformations taken place during calcination of such amorphous films by heat-treatment in air to crystalline hematite have been determined. Investigations on the calcination effects of thick iron anodic films reported here offer opportunities for both fundamental research and practical applications.

  6. Bilayered buccal films as child-appropriate dosage form for systemic administration of propranolol.

    Science.gov (United States)

    Abruzzo, Angela; Nicoletta, Fiore Pasquale; Dalena, Francesco; Cerchiara, Teresa; Luppi, Barbara; Bigucci, Federica

    2017-10-05

    Buccal mucosa has emerged as an attractive site for systemic administration of drug in paediatric patients. This route is simple and non-invasive, even if the saliva wash-out effect and the relative permeability of the mucosa can reduce drug absorption. Mucoadhesive polymers represent a common employed strategy to increase the contact time of the formulation at the application site and to improve drug absorption. Among the different mucoadhesive dosage forms, buccal films are particularly addressed for paediatric population since they are thin, adaptable to the mucosal surface and able to offer an exact and flexible dose. The objective of the present study was to develop bilayered buccal films for the release of propranolol hydrochloride. A primary polymeric layer was prepared by casting and drying of solutions of film-forming polymers, such as polyvinylpyrrolidone (PVP) or polyvinylalcohol (PVA), added with different weight ratios of gelatin (GEL) or chitosan (CH). In order to achieve unidirectional drug delivery towards buccal mucosa, a secondary ethylcellulose layer was applied onto the primary layer. Bilayered films were characterized for their physico-chemical (morphology, thickness, drug content and solid state) and functional (water uptake, mucoadhesion, drug release and permeation) properties. The inclusion of CH into PVP and PVA primary layer provided the best mucoadhesion ability. Films containing CH provided a lower drug release with respect to films containing GEL and increased the amount of permeated drug through buccal mucosa, thanks to its ability of interfering with the lipid organization. The secondary ethylcellulose layer did not interfere with drug permeation, but it could limit drug release in the buccal cavity. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Antireflective bilayer coatings based on Al2O3 film for UV region

    OpenAIRE

    Marszałek Konstanty; Winkowski Paweł; Marszałek Marta

    2015-01-01

    Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS). Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring syste...

  8. Thin-film silica sol-gels doped with ion responsive fluorescent lipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, D.Y.; Shea, L.E.; Sinclair, M.B.

    1999-01-12

    A metal ion sensitive, fluorescent lipid-b i layer material (5oA PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol-gel immobilization method was quantitative in the entrapment of seif-assembled Iipid-bilayers and yielded thin films for facile configuration to optical fiber piatforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CUCIZ were realized with complete regeneration of the sensor using an ethylenediarninetetraacetic acid (EDTA) solution.

  9. Strongly compressed Bi (111) bilayer films on Bi{sub 2}Se{sub 3} studied by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 (China)

    2015-09-21

    Ultra-thin Bi films show exotic electronic structure and novel quantum effects, especially the widely studied Bi (111) film. Using reflection high-energy electron diffraction and scanning tunneling microscopy, we studied the structure and morphology evolution of Bi (111) thin films grown on Bi{sub 2}Se{sub 3}. A strongly compressed, but quickly released in-plane lattice of Bi (111) is found in the first three bilayers. The first bilayer of Bi shows a fractal growth mode with flat surface, while the second and third bilayer show a periodic buckling due to the strong compression of the in-plane lattice. The lattice slowly changes to its bulk value with further deposition of Bi.

  10. Characterization of bilayer-metal contacts to high Tc superconducting films

    International Nuclear Information System (INIS)

    Ma, Q.Y.; Schmidt, M.T.; Weinman, L.S.; Yang, E.S.; Sampere, S.M.; Chan, S.

    1991-01-01

    Low resistivity normal metal contacts to YBa 2 Cu 3 O 7-x (YBCO) films have been investigated. It has previously shown that the contact resistivity of Au contact exhibits a strong temperature dependence, decreasing 2--3 orders of magnitude at a transition temperature near T c of YBCO film. Other metal contacts, including Pd and Nb, do not show this effect. The contact resistivity of metal contacts has been correlated with interfacial reactions and disruption studied by x-ray photoelectron spectroscopy (XPS). In this work we demonstrate that a thin interlayer, specifically 10 A of Au, between the YBCO and a metal contact such as Nb can allow the formation of a low resistance contact. XPS of the effect of the interlayer is presented, and the implications for carrier coupling are discussed. These results indicate a methodology for low contact resistance bilayer-metal structures for supercondcuting device applications

  11. A metastable HCP intermetallic phase in Cu-Al bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Limei

    2006-07-01

    For the present study, three kinds of layered Cu/Al films have been fabricated. The first kind of samples were multilayered Cu/Al films deposited by sputtering on (001)Si. The individual layer thicknesses were 100 nm, 200 nm and 400 nm, while the total film thickness of 800 nm was kept constant, thus leading to multilayer systems with 8, 4 and 2 layers, respectively. The second type of samples were Cu/Al bilayer films grown on (0001) sapphire by sputtering, with individual layer thicknesses of 400 nm. The third type of samples were bilayer films (100 nm Cu and 100 nm Al) deposited on (0001)sapphire by MBE at room temperature. Applying conventional transmission electron microscopy and X-ray diffraction, different epitaxial growth behaviors were found in these films. All multilayer films from the first type were polycrystalline. The second type of films show a (111) FCC texture and possess intermetallic phases at the interfaces. HRTEM investigations displayed that along [111]FCC, the atomic structure of the interlayer has an ABAB stacking sequence, which is identical with a hexagonal close-packed (HCP) structure in [0001] direction, but not with the ABCABC stacking sequence of Cu and Al in [111]FCC. The lattice parameters of the HCP structure at the interlayer were determined from a model which gave the best agreement between the experimental and simulated images. The parameters are: a=b=0.256 nm, c=0.419 nm, ?=120 , with the space group of P6m2. Furthermore, lattice distortion analysis revealed that the lattice parameters of the HCP phase are increasing from the near-Cu-side to the near-Al-side. The chemical composition of the interlayer was investigated by energy dispersive X-ray spectroscopy (EDS). EDS linescans were performed from pure Al to pure Cu layers. In order to examine the stability of this HCP phase, in-situ heating experiments were performed in the HRTEM at {proportional_to}600 C. Ex-situ heating experiments were performed at different temperatures to

  12. Multiferroic behavior and impedance spectroscopy of bilayered BiFeO3/CoFe2O4 thin films

    Science.gov (United States)

    Wu, Jiagang; Wang, John

    2009-06-01

    Lead-free bilayered multiferroic thin films consisting of BiFeO3 (BFO) and CoFe2O4 (CFO) layers with different thicknesses were grown on SrRuO3-coated Pt/TiO2/SiO2/Si substrates by radio frequency sputtering. The effects of constituent layer thicknesses on the ferroelectric and magnetic behavior have been studied. The physical behaviors are shown to strongly depend on the thicknesses of the constituent layers. BFO (220 nm)/CFO (30 nm) bilayered thin film demonstrated much improved ferroelectric and ferromagnetic behavior (2Pr=144.2 μC/cm2, 2Ec=778.0 kV/cm, Ms=61.2 emu/cm3, and Hc=200.8 Oe) as compared to those of the single layer BFO thin film. The dielectric behavior and conductivity of BFO (220 nm)/CFO (30 nm) bilayered thin film were investigated as a function of both temperature (in the range of 294-534 K) and frequency (in the range of 10-1-106 Hz), where an activation energy of ˜1.11 eV for dielectric relaxation was demonstrated. From the conductivity behavior, an activation energies of ˜0.98 eV was derived for dc conductivity are, implying that oxygen vacancies are involved in the conduction of the BFO (220 nm)/CFO (30 nm) bilayered film.

  13. Reversible Monolayer-Bilayer Transition in Supported Phospholipid LB Films under the Presence of Water: Morphological and Nanomechanical Behavior.

    Science.gov (United States)

    Ruiz-Rincón, Silvia; González-Orive, Alejandro; de la Fuente, Jesús M; Cea, Pilar

    2017-08-01

    Mixed monolayer Langmuir-Blodgett (LB) films of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol (Chol) in the 1:1 ratio have been prepared onto solid mica substrates. Upon immersion in water or in an aqueous HEPES solution (pH 7.4) the monolayer LB films were spontaneously converted into well-organized bilayers leaving free mica areas. The process has been demonstrated to be reversible upon removal of the aqueous solution, resulting in remarkably free of defects monolayers that are homogeneously distributed onto the mica. In addition, the nanomechanical properties exhibited by the as-formed bilayers have been determined by means of AFM breakthrough force studies. The bilayers formed by immersion of the monolayer in an aqueous media exhibit nanomechanical properties and stability under compression analogous to those of DPPC:Chol supported bilayers obtained by other methods previously described in the literature. Consequently, the hydration of a monolayer LB film has been revealed as an easy method to produce well-ordered bilayers that mimic the cell membrane and that could be used as model cell membranes.

  14. Characterization of casein and casein-silver conjugated nanoparticle containing multifunctional (pectin–sodium alginate/casein) bilayer film

    OpenAIRE

    Bora, Anupama; Mishra, Poonam

    2016-01-01

    Casein nano particles and casein-silver conjugated nano composite containing edible bilayer pouch was developed from a heat sealable casein layer laminated with sodium alginate–pectin layer. The physicochemical, mechanical, biodegradability and the toxicity of the film were evaluated. The synthesized casein nano particle was incorporated in the casein layer (inner layer) of the film, however, the casein-silver conjugated nano composite were incorporated in the sodium alginate–pectin (outer) l...

  15. Raman spectra of bilayer graphene covered with Poly(methyl methacrylate thin film

    Directory of Open Access Journals (Sweden)

    Minggang Xia

    2012-09-01

    Full Text Available The Raman spectra of bilayer graphene covered with poly(methyl methacrylate (PMMA were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

  16. Analysis of wide color gamut of green/red bilayered freestanding phosphor film-capped white LEDs for LCD backlight.

    Science.gov (United States)

    Oh, Ji Hye; Kang, Heejoon; Ko, Minji; Do, Young Rag

    2015-07-27

    In this study, we propose green/red bilayered freestanding phosphor film-capped white light-emitting diodes (W-LEDs) using InGaN blue LEDs and narrowband red and green phosphors to realize a wide color gamut in a liquid crystal display (LCD) backlight system. The narrowband K2SiF6:Mn4+ (KSF) red and SrGa2S4:Eu2+ (SGS) green phosphors are synthesized using a facile etching synthetic process and flux-aided solid state reaction under a H2S atmosphere, respectively, and the freestanding phosphor films are fabricated using a delamination method with water-soluble polymer, polystyrene sulfonic acid, PEDOT/PSS, and interlayered phosphor film. Various phosphor concentrations of green/red bilayered freestanding phosphor film-capped W-LEDs exhibit a correlated color temperature (CCT) and luminous efficacy range of 11,390 K ~6,540 K and 99 lm/W ~124 lm/W, respectively, with an applied current of 60 mA. The W-LED with green (12.5 wt%)/red (40 wt%) bilayered phosphor film, which exhibited luminous efficacy of 105 lm/W at the CCT of 8,330 K, is selected and the color gamut of the bare LED and phosphor RG and the filtered RGB triangle is calculated to be more than ~95% and ~86.4%, respectively, relative to the NTSC in the 1931 CIE color coordinates space.

  17. Polymerization of diacetylene phospolipid bilayers on solid substrate: Influence of the film deposition temperature

    NARCIS (Netherlands)

    Morigaki, Kenichi; Schönherr, Holger; Okazaki, Takashi

    2007-01-01

    Micropatterned phospholipid bilayers on solid substrates offer an attractive platform for various applications, such as high throughput drug screening. We have previously developed a photopolymerization-based methodology for generating micropatterned bilayers composed of polymerized and fluid lipid

  18. Investigation of inter-diffusion in bilayer GeTe/SnSe phase change memory films

    International Nuclear Information System (INIS)

    Devasia, Archana; MacMahon, David; Raoux, Simone; Campbell, Kristy A.; Kurinec, Santosh K.

    2012-01-01

    A metal-chalcogenide layer, SnSe, is inserted between the memory layer GeTe and the top electrode to form a phase change memory cell. The GeTe layer exhibits ovonic threshold switching at a threshold field of ∼ 110 V/μm. For subsequent implementation into applications and reliability, material inter-diffusion and sublimation are examined in bilayer phase change films of GeTe/SnSe. Transmission electron microscopy and parallel electron energy loss spectroscopy analyses reveal Sn migration to the GeTe layer, which is responsible for lowering the rhombohedral to cubic structural transformation temperature in GeTe. Incongruent sublimation of SnSe and GeTe is observed at temperatures higher than 500 °C. Severe volatilization of Se results in the separation of a metallic Sn phase. The use of Al 2 O 3 as a capping layer has been found to mitigate these effects. - Highlights: ► In the as-deposited state, GeTe is amorphous and SnSe is orthorhombic in structure. ► After 300 °C, Sn migration results in the formation of a Ge x Sn 1−x Te solid solution. ► Film decomposition and incongruent sublimation are observed at high temperatures. ► A consequence of incongruent sublimation is the separation of metallic Sn phase. ► Al2O3 capping mitigates volatilization and Sn phase separation at high temperatures.

  19. A hierarchically porous anatase TiO2 coated-WO3 2D IO bilayer film and its photochromic properties.

    Science.gov (United States)

    Li, Hua; Wu, Huazhong; Xiao, Jiajia; Su, Yanli; Robichaud, Jacques; Brüning, Ralf; Djaoued, Yahia

    2016-01-18

    A hierarchically porous anatase TiO2 coated-WO3 2D inverse opal (IO) bilayer film was fabricated on ITO glass using a layer by layer route with a hierarchically porous TiO2 top layer and an ordered super-macroporous WO3 2D IO bottom layer. This novel TiO2 coated-WO3 2D IO bilayer film was evaluated for photochromic applications.

  20. Study on the enhanced and stable field emission behavior of a novel electrosprayed Al-doped ZnO bilayer film

    KAUST Repository

    Mahmood, Khalid

    2014-01-01

    A novel electrosprayed bilayer film composed of an over-layer (L 2) of aluminium-doped ZnO (AZO) nanoflakes (NF-AZO) and a under-layer (L1) of AZO nanocrystallites structure (NC-AZO) named BL:NF/NC-AZO is studied as an excellent field-emitter. The XRD pattern demonstrated that the doped bilayer film has preferential growth along the c-axis with hexagonal wurtzite structure and the (0 0 2) peak shifted toward the larger angle side after doping. The lowest turn-on field of ∼2.8 V μm-1, highest emission current density of 1.95 mA cm-2 is obtained for BL:NF/NC-AZO under the field of 6.8 V μm-1 and as well as the highest field enhancement factor (β) is estimated to be 4370 ± 3, compared to pure ZnO bilayer film (BL:NF/NC-ZnO) and also better than NC-AZO film and possesses the excellent long term stability of emission current. The PL intensity of doped ZnO bilayer film is very much stronger than pure ZnO bilayer structure. The superior field emission properties are attributed to the better morphologies, Al-doping and better crystallinity of bilayer AZO films. © 2014 The Royal Society of Chemistry.

  1. Fabrication of bi-layer graphene and theoretical simulation for its possible application in thin film solar cell.

    Science.gov (United States)

    Behura, Sanjay K; Mahala, Pramila; Nayak, Sasmita; Yang, Qiaoqin; Mukhopadhyay, Indrajit; Janil, Omkar

    2014-04-01

    High quality graphene film is fabricated using mechanical exfoliation of highly-oriented pyrolytic graphite. The graphene films on glass substrates are characterized using field-emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy, UV-vis spectroscopy and Fourier transform infrared spectroscopy. A very high intensity ratio of 2D to G-band (to approximately 1.67) and narrow 2D-band full-width at half maximum (to approximately 40 cm(-1)) correspond to the bi-layer graphene formation. The bi-layer graphene/p-GaN/n-InGaN/n-GaN/GaN/sAl2O3 system is studied theoretically using TCAD Silvaco software, in which the properties of exfoliated bi-layer graphene are used as transparent and conductive film, and the device exhibits an efficiency of 15.24% compared to 13.63% for ITO/p-GaN/n-InGaN/n-GaN/GaN/Al2O3 system.

  2. Characterization of casein and casein-silver conjugated nanoparticle containing multifunctional (pectin-sodium alginate/casein) bilayer film.

    Science.gov (United States)

    Bora, Anupama; Mishra, Poonam

    2016-10-01

    Casein nano particles and casein-silver conjugated nano composite containing edible bilayer pouch was developed from a heat sealable casein layer laminated with sodium alginate-pectin layer. The physicochemical, mechanical, biodegradability and the toxicity of the film were evaluated. The synthesized casein nano particle was incorporated in the casein layer (inner layer) of the film, however, the casein-silver conjugated nano composite were incorporated in the sodium alginate-pectin (outer) layer of the film. The mechanical, barrier, physical and antimicrobial properties of the film were investigated. Addition of nano composite/nano particle reduced the water solubility (from 67 to 46 % at 80 °C temperature) of the film improved the water barrier properties, light barrier properties, tensile strength and thermal properties of the film. The light barrier properties of the film increased and transparency reduced with increase in silver content in the conjugated nano composite film. The nano particles/nano composite containing film showed antibacterial activity against E. coli . The films were recorded safe for red blood cells as % haemolysis for all the tested samples were found to be well below the safe level.

  3. Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution

    Directory of Open Access Journals (Sweden)

    A. Herz

    2016-03-01

    Full Text Available Self-assembly of ultrathin Au, W, and Au-W bilayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Au films is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO2 evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI oxide (WO3 which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO3 is realized by using various bilayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W bilayer thin film, W acts either as a substrate or as a passivation layer for the dewetting of Au. Being the ground layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top layer, W prevents Au from dewetting regardless of Au film thickness. Moreover, regular pattern formation of Au-WO3 nanoparticles is observed at high temperature demonstrating how bilayer thin film dewetting can create unique nanostructure arrangements.

  4. Controlling the Performance of P-type Cu2O/SnO Bilayer Thin-Film Transistors by Adjusting the Thickness of the Copper Oxide Layer

    KAUST Repository

    Al-Jawhari, Hala A.

    2014-11-11

    The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films as the lower layer we built a matrix of bottom-gate Cu2O/SnO bilayer thin-film transistors of different thickness. We found that the thickness of the Cu2O layer is of major importance in oxidation of the SnO layer underneath. The thicker the Cu2O layer, the more the underlying SnO layer is oxidized, and, hence, the more transistor mobility is enhanced at a specific temperature. Both device performance and the annealing temperature required could be adjusted by controlling the thickness of each layer of Cu2O/SnO bilayer thin-film transistors.

  5. Thin film free-standing PEDOT:PSS/SU8 bilayer microactuators

    Science.gov (United States)

    Taccola, S.; Greco, F.; Mazzolai, B.; Mattoli, V.; Jager, E. W. H.

    2013-11-01

    Several smart active materials have been proposed and tested for the development of microactuators. Among these, conjugated polymers are of great interest because miniaturization improves their electrochemical properties, such as increasing the speed and stress output of microactuators, with respect to large-scale actuators. Recently we developed a novel fabrication process to obtain robust free-standing conductive ultra-thin films made of the conjugated polymer poly(3, 4-ethylenedioxythiophene) doped with the polyanion poly(styrenesulfonate) (PEDOT:PSS). These conductive free-standing nanofilms, with thicknesses ranging between a few tens to several hundreds of nm, allow the realisation of new all polymer microactuators using facile microfabrication methods. Here, we report a novel processing method for manufacturing all polymer electrochemical microactuators. We fabricated and patterned free-standing PEDOT:PSS/SU8 bilayer microactuators in the form of microfingers of a variety of lengths using adapted microfabrication procedures. By imposing electrochemical oxidation/reduction cycles on the PEDOT:PSS we were able to demonstrate reversible actuation of the microactuators resulting in bending of the microfingers. A number of possible applications can be envisaged for these small, soft actuators, such as microrobotics and cell manipulation.

  6. Photovoltaic behaviour of titanyl phthalocyanine thin films and titania bilayer films

    Czech Academy of Sciences Publication Activity Database

    Drabik, M.; Zachary, A. M.; Choi, Y.; Hanuš, J.; Toušek, J.; Toušková, J.; Cimrová, Věra; Slavinská, D.; Biederman, H.; Hanley, L.

    2008-01-01

    Roč. 268, č. 1 (2008), s. 57-60 ISSN 1022-1360. [Microsymposium on Advanced Polymer Materials for Photonics and Electronics /47./. Prague, 15.07.2007-19.07.2007] R&D Projects: GA MŠk(CZ) 1M06031 Grant - others:National Science Foundation(US) CHE0241425; GA MŠk(CZ) 1P05ME754 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * photovoltaics * phthalocyanine * thin films * titania Subject RIV: BM - Solid Matter Physics ; Magnetism

  7. Process parameter impact on properties of sputtered large-area Mo bilayers for CIGS thin film solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Badgujar, Amol C.; Dhage, Sanjay R., E-mail: dhage@arci.res.in; Joshi, Shrikant V.

    2015-08-31

    Copper indium gallium selenide (CIGS) has emerged as a promising candidate for thin film solar cells, with efficiencies approaching those of silicon-based solar cells. To achieve optimum performance in CIGS solar cells, uniform, conductive, stress-free, well-adherent, reflective, crystalline molybdenum (Mo) thin films with preferred orientation (110) are desirable as a back contact on large area glass substrates. The present study focuses on cylindrical rotating DC magnetron sputtered bilayer Mo thin films on 300 mm × 300 mm soda lime glass (SLG) substrates. Key sputtering variables, namely power and Ar gas flow rates, were optimized to achieve best structural, electrical and optical properties. The Mo films were comprehensively characterized and found to possess high degree of thickness uniformity over large area. Best crystallinity, reflectance and sheet resistance was obtained at high sputtering powers and low argon gas flow rates, while mechanical properties like adhesion and residual stress were found to be best at low sputtering power and high argon gas flow rate, thereby indicating a need to arrive at a suitable trade-off during processing. - Highlights: • Sputtering of bilayer molybdenum thin films on soda lime glass • Large area deposition using rotating cylindrical direct current magnetron • Trade of sputter process parameters power and pressure • High uniformity of thickness and best electrical properties obtained • Suitable mechanical and optical properties of molybdenum are achieved for CIGS application.

  8. Vacuum-assisted bilayer PEDOT:PSS/cellulose nanofiber composite film for self-standing, flexible, conductive electrodes.

    Science.gov (United States)

    Ko, Youngsang; Kim, Dabum; Kim, Ung-Jin; You, Jungmok

    2017-10-01

    Sustainable cellulose nanofiber (CNF)-based composites as functional conductive materials have garnered considerable attention recently for their use in soft electronic devices. In this work, self-standing, highly flexible, and conductive PEDOT:PSS-CNF composite films were developed using a simple vacuum-assisted filtration method. Two different composite films were successfully fabricated and then tested: 1) a single-layer composite composed of a mixture of PEDOT:PSS and CNF phases and 2) a bilayer composite composed of an upper PEDOT:PSS membrane layer and a CNF matrix sub-layer. The latter composite was constructed by electrostatic/hydrogen bonding interactions between PEDOT:PSS and CNFs coupled with sequential vacuum-assisted filtration. Our results demonstrated that the resultant bilayer composite film exhibited a competitive electrical conductivity (ca. 22.6Scm -1 ) compared to those of previously reported cellulose-based composites. Furthermore, decreases in the electrical properties were not observed in the composite films when they were bent up to 100 times at an angle of 180° and bent multiple times at an angle of 90°, clearly demonstrating their excellent mechanical flexibility. This study provides a straightforward method of fabricating highly flexible, lightweight, and conductive films, which have the potential to be used in high-performance soft electronic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Multiferroic properties of a YCrO3/BiFeO3 bilayered thin film prepared by a sol-gel method

    Science.gov (United States)

    Kuang, Daihong; Yang, Fangyuan; Jing, Weiwen; Yang, Zhanjin

    2018-02-01

    YCrO3 (YCO), BiFeO3 (BFO), and YCrO3/BiFeO3 (YCO-BFO) thin films were prepared on quartz substrates using spin coating by a sol-gel method. X-ray diffraction demonstrated that YCO and BFO thin films had a perovskite orthorhombic, and rhombohedral structure, respectively. The stronger and sharper diffraction intensity of YCO-BFO bilayered thin film indicated that the bottom YCO layer was able to promote the grain growth of BFO film, which was further verified by scanning electron microscope. The ferroelectric test demonstrated that the leakage current density of YCO-BFO bilayered film was reduced by one order of magnitude compared to that of BFO film, which had a better ferroelectric property. Optical absorption spectra indicated that the band gap of YCO-BFO thin film was lower than that of BFO film, suggesting their potential application as UV and blue-green-driven photocatalysts. The magnetic test verified that the ferromagnetic property of YCO-BFO film was obviously enhanced compared to those of BFO and YCO thin films. The results revealed that YCO layer played an important role for improving multiferroic properties of BFO thin film. The mechanisms of the effects of bottom YCO layer on optical and multiferroic properties of BFO thin film in the YCO-BFO bilayered film were discussed in detail.

  10. Corrosion resistance of the NdFeB coated with AlN/SiC bilayer thin films by magnetron sputtering under different environments

    International Nuclear Information System (INIS)

    Tao, Lei; Li, Heqin; Shen, Jiong; Qiao, Kai; Wang, Wei; Zhou, Chu; Zhang, Jing; Tang, Qiong

    2015-01-01

    The AlN/SiC bilayer and SiC monolayer thin films were deposited on sintered NdFeB by RF magnetron sputtering to improve the corrosion resistance. Their structures and morphologies were studied by XRD and AFM and SEM. The corrosion behaviors of AlN/SiC and SiC-coated NdFeB in 3.5 wt% NaCl, 20 wt% NaOH and 0.1 mol/L H 2 SO 4 solutions were characterized with potentiodynamic polarization curves. The results show that AlN/SiC and SiC thin films can evidently improve the corrosion resistance of NdFeB, and the AlN/SiC films have the better resistance than the SiC film. - Highlights: • SiC monolayer and AlN/SiC bilayer thin films have been prepared on NdFeB at room temperature by RF magnetron sputtering. • NdFeB coated with AlN/SiC bilayer films has more corrosion resistance than that coated with SiC monolayer film under different environments. • The grains of the AlN/SiC bilayer films are finer and the surface roughness is lower than that of SiC monolayer film

  11. Corrosion resistance of the NdFeB coated with AlN/SiC bilayer thin films by magnetron sputtering under different environments

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Lei [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Shen, Jiong [Earth-Panda Advance Magnetic Material Co., Ltd., Anhui Lujiang 231500 (China); Qiao, Kai; Wang, Wei; Zhou, Chu [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Anhui Hefei 230009 (China)

    2015-02-01

    The AlN/SiC bilayer and SiC monolayer thin films were deposited on sintered NdFeB by RF magnetron sputtering to improve the corrosion resistance. Their structures and morphologies were studied by XRD and AFM and SEM. The corrosion behaviors of AlN/SiC and SiC-coated NdFeB in 3.5 wt% NaCl, 20 wt% NaOH and 0.1 mol/L H{sub 2}SO{sub 4} solutions were characterized with potentiodynamic polarization curves. The results show that AlN/SiC and SiC thin films can evidently improve the corrosion resistance of NdFeB, and the AlN/SiC films have the better resistance than the SiC film. - Highlights: • SiC monolayer and AlN/SiC bilayer thin films have been prepared on NdFeB at room temperature by RF magnetron sputtering. • NdFeB coated with AlN/SiC bilayer films has more corrosion resistance than that coated with SiC monolayer film under different environments. • The grains of the AlN/SiC bilayer films are finer and the surface roughness is lower than that of SiC monolayer film.

  12. Proximity effects at the interface of a superconductor and a topological insulator in NbN-Bi2Se3 thin film bilayers

    International Nuclear Information System (INIS)

    Koren, Gad

    2015-01-01

    In a search for a simple proximity system of a topological insulator and a superconductor for studying the role of surface versus bulk effects by gating, we report here on a first step toward this goal, namely the choice of such a system and its characterization. We chose to work with thin film bilayers of grainy 5 nm thick NbN films as the superconductor, overlayed with 20 nm thick topological layer of Bi 2 Se 3 and compare the transport results to those obtained on a 5 nm thick reference NbN film on the same wafer. Bilayers with ex situ and in situ prepared NbN-Bi 2 Se 3 interfaces were studied and two kinds of proximity effects were found. At high temperatures just below the superconducting transition, all bilayers showed a conventional proximity effect where the topological Bi 2 Se 3 suppresses the onset or mid-transition T c of the superconducting NbN films by about 1 K. At low temperatures, a cross-over of the resistance versus temperature curves of the bilayer and reference NbN film occurs, where the bilayers show enhancement of T c (R=0), I c (the supercurrent) and the Andreev conductance, as compared to the bare NbN films. This indicates that superconductivity is induced in the Bi 2 Se 3 layer at the interface region in between the NbN grains. Thus an inverse proximity effect in the topological material is demonstrated. (paper)

  13. Antireflective bilayer coatings based on Al2O3 film for UV region

    Directory of Open Access Journals (Sweden)

    Marszałek Konstanty

    2015-03-01

    Full Text Available Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS. Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring system Inficon XTC/2. The experimental results of the optical measurements carried out during and after the deposition process have been presented. Physical thickness measurements were made during the deposition process and resulted in 44 nm/52 nm for Al2O3/MgF2 and 44 nm/50 nm for Al2O3/SiO2 system. Optimization was carried out for ultraviolet region with minimum of reflectance at 300 nm. The influence of post deposition annealing on the crystal structure was determined by X-ray measurements. In the range from ultraviolet to the beginning of visible region, the reflectance of both systems decreased and reached minimum at 290 nm. The value of reflectance at this point, for the coating Al2O3/MgF2 was equal to R290nm = 0.6 % and for Al2O3/SiO2R290nm = 1.1 %. Despite the difference between these values both are sufficient for applications in the UV optical systems for medicine and UV laser technology.

  14. Annealing effect on the structural, morphological and electrical properties of TiO2/ZnO bilayer thin films

    Science.gov (United States)

    Khan, M. I.; Imran, S.; Shahnawaz; Saleem, Muhammad; Ur Rehman, Saif

    2018-03-01

    The effect of annealing temperature on the structural, morphological and electrical properties of TiO2/ZnO (TZ) thin films has been observed. Bilayer thin films of TiO2/ZnO are deposited on FTO glass substrate by spray pyrolysis method. After deposition, these films are annealed at 573 K, 723 K and 873 K. XRD shows that TiO2 is present in anatase phase only and ZnO is present in hexagonal phase. No other phases of TiO2 and ZnO are present. Also, there is no evidence of other compounds like Zn-Ti etc. It also shows that the average grain size of TiO2/ZnO films is increased by increasing annealing temperature. AFM (Atomic force microscope) showed that the average roughness of TiO2/ZnO films is decreased at temperature 573-723 K and then increased at 873 K. The calculated average sheet resistivity of thin films annealed at 573 K, 723 K and 873 K is 152.28 × 102, 75.29 × 102 and 63.34 × 102 ohm-m respectively. This decrease in sheet resistivity might be due to the increment of electron concentration with increasing thickness and the temperature of thin films.

  15. Platinum/titanium bilayer deposited on polymer film as efficient counter electrodes for plastic dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Ikegami, M.; Miyoshi, K.; Miyasaka, T.; Teshima, K.; Wei, T. C.; Wan, C. C.; Wang, Y. Y.

    2007-01-01

    A surface-rich platinum/titanium bilayer was deposited on poly(ethylene naphthalate) film by vacuum sputtering as counterelectrode for plastic dye-sensitized solar cells (DSSCs). Compared to the electrodes made of pure Pt layer, this electrode maintained similar electrochemical catalytic effect at relative low Pt usage. Current-voltage characteristics of the plastic DSSC at this stage stand at 0.69 V on V OC , 9.97 mA/cm 2 on I SC , 0.69 on fill factor, and 4.31% cell efficiency under AM1.5, 100 mW/cm 2 illumination

  16. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Feng, Yamin; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang

    2013-01-01

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm −2 illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes

  17. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yamin, E-mail: yaminfengccnuphy@outlook.com; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang, E-mail: xthuang@phy.ccnu.edu.cn

    2013-12-25

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm{sup −2} illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes.

  18. Non-leaky modes and bandgaps of surface acoustic waves in wrinkled stiff-film/compliant-substrate bilayers

    Science.gov (United States)

    Li, Guo-Yang; Xu, Guoqiang; Zheng, Yang; Cao, Yanping

    2018-03-01

    Surface acoustic wave (SAW) devices have found a wide variety of technical applications, including SAW filters, SAW resonators, microfluidic actuators, biosensors, flow measurement devices, and seismic wave shields. Stretchable/flexible electronic devices, such as sensory skins for robotics, structural health monitors, and wearable communication devices, have received considerable attention across different disciplines. Flexible SAW devices are essential building blocks for these applications, wherein piezoelectric films may need to be integrated with the compliant substrates. When piezoelectric films are much stiffer than soft substrates, SAWs are usually leaky and the devices incorporating them suffer from acoustic losses. In this study, the propagation of SAWs in a wrinkled bilayer system is investigated, and our analysis shows that non-leaky modes can be achieved by engineering stress patterns through surface wrinkles in the system. Our analysis also uncovers intriguing bandgaps (BGs) related to the SAWs in a wrinkled bilayer system; these are caused by periodic deformation patterns, which indicate that diverse wrinkling patterns could be used as metasurfaces for controlling the propagation of SAWs.

  19. Control of the optical and crystalline properties of TiO2 in visible-light active TiO2/TiN bi-layer thin-film stacks

    International Nuclear Information System (INIS)

    Smith, Wilson; Fakhouri, Houssam; Pulpytel, Jerome; Arefi-Khonsari, Farzaneh

    2012-01-01

    Multi-layered thin films of TiO 2 and TiN were created by rf reactive magnetron sputtering, and their crystalline, optical, and photoelectrochemical properties were measured. The overall composition of the films (TiO 2 -to-TiN ratio) was kept constant with the height of each film. The number of layers and thickness of each layer was controlled to create bi-layer thin films that were composed of: 9 bi-layers, 18 bi-layers, 27 bi-layers, 36 bi-layers, and 45 bi-layers. XRD patterns were observed for each film after annealing to measure the grain size and composition of anatase and rutile as a function of temperature. It was found that the phase-transition temperature is able to be substantially controlled (between 550 deg. C and 850 deg. C) for the anatase to rutile transition by varying the number of layers/thickness of each layer. In addition, bi-layer stacking significantly affected the film's optical properties by lowering the bandgap into the visible-light region, and also showed up to three times the improvement in photoelectrochemical performance under uv and visible irradiation. Overall, bi-layer stacking of TiO 2 /TiN films has shown a unique and highly desirable control over several important physical characteristics that can be beneficial for many applications, such as high-temperature sensors and optoelectronic devices.

  20. Thermo-Optical Properties of Thin-Film TiO2–Al2O3 Bilayers Fabricated by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rizwan Ali

    2015-05-01

    Full Text Available We investigate the optical and thermo-optical properties of amorphous TiO\\(_2\\–Al\\(_2\\O\\(_3\\ thin-film bilayers fabricated by atomic layer deposition (ALD. Seven samples of TiO\\(_2\\–Al\\(_2\\O\\(_3\\ bilayers are fabricated by growing Al\\(_2\\O\\(_3\\ films of different thicknesses on the surface of TiO\\(_2\\ films of constant thickness (100 nm. Temperature-induced changes in the optical refractive indices of these thin-film bilayers are measured by a variable angle spectroscopic ellipsometer VASE\\textsuperscript{\\textregistered}. The optical data and the thermo-optic coefficients of the films are retrieved and calculated by applying the Cauchy model and the linear fitting regression algorithm, in order to evaluate the surface porosity model of TiO\\(_2\\ films. The effects of TiO\\(_2\\ surface defects on the films' thermo-optic properties are reduced and modified by depositing ultra-thin ALD-Al\\(_2\\O\\(_3\\ diffusion barrier layers. Increasing the ALD-Al\\(_2\\O\\(_3\\ thickness from 20 nm to 30 nm results in a sign change of the thermo-optic coefficient of the ALD-TiO\\(_2\\. The thermo-optic coefficients of the 100 nm-thick ALD-TiO\\(_2\\ film and 30 nm-thick ALD-Al\\(_2\\O\\(_3\\ film in a bilayer are (0.048 \\(\\pm\\ 0.134 \\(\\times 10 ^{-4} {^\\circ}\\mathrm {C}^{-1}\\ and (0.680 \\(\\pm\\ 0.313 \\(\\times 10^{-4} {^\\circ} \\mathrm {C}^{-1}\\, respectively, at a temperature \\(T = 62 ^\\circ \\mathrm{C}\\.

  1. Hybrid thin films based on bilayer heterojunction of titania nanocrystals/polypyrrole/natural dyes (Kappaphycus alvarezii) materials

    Science.gov (United States)

    Ghazali, Salmah Mohd; Salleh, Hasiah; Dagang, Ahmad Nazri; Ghazali, Mohd Sabri Mohd; Ali, Nik Aziz Nik; Rashid, Norlaily Abdul; Kamarulzaman, Nurul Huda; Ahmad, Wan Almaz Dhafina Che Wan

    2017-09-01

    In this research, hybrid thin films which consist of a combination of organic red seaweed (RS) (Kappaphycus alvarezii) and polypyrrole (PPy) with inorganic titania nanocrystals (TiO2 NCs) materials were fabricated. These hybrid thin films were fabricated accordingly with bilayer heterojunction of ITO/TiO2 NCs/PPy/RS via electrochemical method using Electrochemical Impedance Spectroscopy (EIS). The effect of number of scans (thickness) of titania on optical and electrical properties of hybrid thin films were studied. TiO2 NCs function as an electron acceptor and electronic conductor. Meanwhile, PPy acts as holes conductor and RS dye acts as a photosensitizer enhances the optical and electrical properties of the thin films. The UV absorption spectrum of TiO2 NCs, PPy and RS are characterized by UV-Visible spectroscopy, while the functional group of RS was characterized by Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectra showed that TiO2 NCs, PPy and RS were absorbed over a wide range of light spectrum which were 200-300 nm, 300-900 nm and 250-900 nm; respectively. The FTIR spectra of the RS showed the presence of hydroxyl group which was responsible for a good sensitizer for these hybrid solar cells. The electrical conductivity of these hybrid thin films were measured by using four point probes. The electrical conductivity of ITO/ (1)TiO2 NCs/PPy/RS thin film under the radiation of 100 Wm-2 was 0.062 Scm-1, hence this hybrid thin films can be applied in solar cell application.

  2. The Influence of New Hydrophobic Silica Nanoparticles on the Surface Properties of the Films Obtained from Bilayer Hybrids

    Directory of Open Access Journals (Sweden)

    Cristian Petcu

    2017-02-01

    Full Text Available Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS and tetramethoxysilane (TMOS (1:4 molar ratio as precursors. After coating, silica nanoparticles (SiO2 NPs functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR. The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200–400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8 has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°, compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness.

  3. Novel method for fabrication of integrated resistors on bilayer Ag/YBa2Cu3O7 films using Ni implantation

    International Nuclear Information System (INIS)

    LaGraff, J.R.; Chan, H.; Murduck, J.M.; Hong, S.H.; Ma, Q.Y.

    1997-01-01

    A novel ion implantation method is described for fabricating low inductance integrated resistors on Ag/YBa 2 Cu 3 O 7 (YBCO) bilayer thin films. Parallel high and low value resistors were simultaneously formed by patterning bilayer films into 10-μm-wide lines, then masking and implanting with Ni to selectively inhibit superconductivity in YBCO. Low value resistors (<1Ω/sq) were formed at 77 K as the supercurrent bypassed the Ni-doped nonsuperconducting YBCO and was shunted through the overlying low resistivity Ag metal. High value resistors (20 - 140 Ω/sq) were formed by removing Ag from above the implanted YBCO forcing the current through the implanted YBCO region. The sheet resistance of both types of resistors was found to increase systematically with increasing Ni implant energy. copyright 1997 American Institute of Physics

  4. High extinction ratio and low transmission loss thin-film terahertz polarizer with a tunable bilayer metal wire-grid structure.

    Science.gov (United States)

    Huang, Zhe; Parrott, Edward P J; Park, Hongkyu; Chan, Hau Ping; Pickwell-MacPherson, Emma

    2014-02-15

    A thin-film terahertz polarizer is proposed and realized via a tunable bilayer metal wire-grid structure to achieve high extinction ratios and good transmission. The polarizer is fabricated on top of a thin silica layer by standard micro-fabrication techniques to eliminate the multireflection effects. The tunable alignment of the bilayer aluminum-wire grid structure enables tailoring of the extinction ratio and transmission characteristics. Using terahertz time-domain spectroscopy (THz-TDS), a fabricated polarizer is characterized, with extinction ratios greater than 50 dB and transmission losses below 1 dB reported in the 0.2-1.1 THz frequency range. These characteristics can be improved by further tuning the polarizer parameters such as the pitch, metal film thickness, and lateral displacement.

  5. Using synchrotron-based FT-IR microspectroscopy to study erucamide migration in 50-micron-thick bilayer linear low-density polyethylene and polyolefin plastomer films.

    Science.gov (United States)

    Sankhe, Shilpa Y; Hirt, Douglas E

    2003-01-01

    The diffusion of additives in thick (approximately 500 microns) single layer and multilayer films has been characterized using FT-IR microspectroscopy. The objective of this research was to investigate additive migration and concentration profiles in coextruded multilayer films of industrially relevant thicknesses. In particular, the investigation focused on the migration of an erucamide slip agent in 50-micron-thick coextruded bilayer films of linear low-density polyethylene (LLDPE) and a polyolefin plastomer (POP). Erucamide concentration profiles were successfully mapped using synchrotron-based FT-IR microspectroscopy. The synchrotron radiation helped to achieve a higher spatial resolution for the thin films. Meticulous sample preparation was needed to map the thin film samples. Results with FT-IR microspectroscopy showed that the additive-concentration profiles were relatively uniform across the multilayer-film thickness irrespective of the intended initial additive distribution. For example, a bilayer planned for 1 wt % erucamide in an LLDPE layer and no erucamide in a POP layer showed significant additive migration into the POP layer at the extrusion rates used. FT-IR microspectroscopy results also showed that more erucamide migrated to the surface of a POP layer than an LLDPE layer. Attenuated total reflectance (ATR) FT-IR spectroscopy was used to confirm the time-dependent increase of erucamide surface concentration and that the increase was more pronounced at the surface of the POP layers.

  6. Study of annealing effects in In–Sb bilayer thin films

    Indian Academy of Sciences (India)

    TECS

    The thin films of In–Sb having different thicknesses of antimony keeping constant thickness of indium was deposited by thermal evaporation method on ITO coated conducting glass substrates at room tempera- ture and a pressure of 10. –5 .... Some peaks of indium tin oxide (ITO) are deleted from these XRD data. Present ...

  7. Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

    Science.gov (United States)

    Azzawi, S.; Ganguly, A.; Tokaç, M.; Rowan-Robinson, R. M.; Sinha, J.; Hindmarch, A. T.; Barman, A.; Atkinson, D.

    2016-02-01

    The evolution of damping in Co/Pt, Co/Au, and Ni81Fe19 /Pt bilayers was studied with increasing nonmagnetic (NM) heavy-metal layer thicknesses in the range 0.2 nm ≤tNM≤10 nm , where tNM is the NM layer thickness. Magnetization precession was measured in the time domain using time-resolved magneto-optical Kerr effect magnetometry. Fitting of the data with a damped sinusoidal function was undertaken in order to extract the phenomenological Gilbert damping coefficient α . For Pt-capped Co and Ni81Fe19 layers a large and complex dependence of α on the Pt layer thickness was observed, while for Au capping no significant dependence was observed. It is suggested that this difference is related to the different localized spin-orbit interaction related to intermixing and to d -d hybridization of Pt and Au at the interface with Co or Ni81Fe19 . Also it was shown that damping is affected by the crystal structure differences in FM thin films and at the interface, which can modify the spin-diffusion length and the effective spin-mixing conductance. In addition to the intrinsic damping an extrinsic contribution plays an important role in the enhancement of damping when the Pt capping layer is discontinuous. The dependence of damping on the nonmagnetic layer thickness is complex but shows qualitative agreement with recent theoretical predictions.

  8. Nanoscale magnetism and novel electronic properties of a bilayer bismuth(111) film with vacancies and chemical doping.

    Science.gov (United States)

    Sahoo, M P K; Zhang, Yajun; Wang, Jie

    2016-07-27

    Magnetically doped topological insulators (TIs) exhibit several exotic phenomena including the magnetoelectric effect and quantum anomalous Hall effect. However, from an experimental perspective, incorporation of spin moment into 3D TIs is still challenging. Thus, instead of 3D TIs, the 2D form of TIs may open up new opportunities to induce magnetism. Based on first principles calculations, we demonstrate a novel strategy to realize robust magnetism and exotic electronic properties in a 2D TI [bilayer Bi(111) film: abbreviated as Bi(111)]. We examine the magnetic and electronic properties of Bi(111) with defects such as bismuth monovacancies (MVs) and divacancies (DVs), and these defects decorated with 3d transition metals (TMs). It has been observed that the MV in Bi(111) can induce novel half metallicity with a net magnetic moment of 1 μB. The origin of half metallicity and magnetism in MV/Bi(111) is further explained by the passivation of the σ-dangling bonds near the defect site. Furthermore, in spite of the nonmagnetic nature of DVs, the TMs (V, Cr, Mn, and Fe) trapped at the 5/8/5 defect structure of DVs can not only yield a much higher spin moment than those trapped at the MVs but also display intriguing electronic properties such as metallic, semiconducting and spin gapless semiconducting properties. The predicted magnetic and electronic properties of TM/DV/Bi(111) systems are explained through density of states, spin density distribution and Bader charge analysis.

  9. Superhard behaviour, low residual stress, and unique structure in diamond-like carbon films by simple bilayer approach

    International Nuclear Information System (INIS)

    Dwivedi, Neeraj; Kumar, Sushil; Malik, Hitendra K.

    2012-01-01

    Simple bilayer approach is proposed for synthesizing hard and superhard diamond-like carbon (DLC) coatings with reduced residual stress. For this, M/DLC bilayer (M = Ti and Cu) structures are grown using hybrid system involving radio frequency (RF)-sputtering and RF-plasma enhanced chemical vapor deposition techniques. Ti/DLC bilayer deposited at negative self bias of 100 V shows superhard behaviour with hardness (H) as 49 GPa. Cu/DLC bilayer grown at self bias of 100 V exhibits hard behaviour with H as 22.8 GPa. The hardness of Ti/DLC (Cu/DLC) bilayer gets changed from superhard (hard) to hard (moderate hard) regime, when the self bias is raised to 300 V. Residual stress in Ti/DLC (Cu/DLC) bilayer is found to be significantly low that varies in the range of 1 GPa-1.65 GPa (0.8 GPa-1.6 GPa). The microstructure and morphology are studied by Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). SEM and AFM pictures reveal the creation of nanostructured features in the deposited bilayers. Raman, SEM, and AFM analyses are correlated with the nano-mechanical properties. Owing to excellent nano-mechanical properties, these bilayers can find their direct industrial applications as hard and protective coatings.

  10. Effects of V2O5/Au bi-layer electrodes on the top contact Pentacene-based organic thin film transistors

    Science.gov (United States)

    Borthakur, Tribeni; Sarma, Ranjit

    2017-05-01

    Top-contact Pentacene-based organic thin film transistors (OTFTs) with a thin layer of Vanadium Pent-oxide between Pentacene and Au layer are fabricated. Here we have found that the devices with V2O5/Au bi-layer source-drain electrode exhibit better field-effect mobility, high on-off ratio, low threshold voltage and low sub-threshold slope than the devices with Au only. The field-effect mobility, current on-off ratio, threshold voltage and sub-threshold slope of V2O5/Au bi-layer OTFT estimated from the device with 15 nm thick V2O5 layer is .77 cm2 v-1 s-1, 7.5×105, -2.9 V and .36 V/decade respectively.

  11. Reporting performance in MoS{sub 2}–TiO{sub 2} bilayer and heterojunction films based dye-sensitized photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    He, Zuoli, E-mail: wandaohzl@163.com; Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn; Xing, Yonglei; Liu, Xiaobin

    2016-07-05

    Three types of bilayer and heterojunction films photoanodes were designed and fabricated from green synthesized MoS{sub 2} and TiO{sub 2} nanoparticles (NPs), and then the dye-sensitized solar cells based on these various films photoanodes were investigated. Results demonstrated that layered semiconductor MoS{sub 2} could be a viable material candidate for solar cell applications due to its superior photoelectric characteristics. The DSSCs from the MoS{sub 2}@TiO{sub 2} heterojunction film photoanode exhibit the highest solar energy conversion efficiency of 6.02% under AM 1.5G simulated solar irradiation, which is 1.5 times higher than that of the cell from pure TiO{sub 2} film photoanode. MoS{sub 2}–TiO{sub 2} heterojunction at the interface helps MoS{sub 2} NPs to efficiently collect the photo-injected electrons from TiO{sub 2} NPs, thus reduce charge recombination at both the NPs-electrolyte and NPs-dye interfaces. These advantages together with collecting or transferring injected electrons abilities by combining the improved light absorption and the large dye-loading capacity of such structural NPs films, rendering the MoS{sub 2}–TiO{sub 2} composite photoelectrode superior potential for DSSCs applications. - Highlights: • MoS{sub 2} and TiO{sub 2} NPs were synthesized via green process using rape pollen grains as bio-templates. • DSSCs based on these various bilayer and heterojunction films photoanodes were investigated. • Enhanced η of MoS{sub 2}@TiO{sub 2} based DSSCs was related to its strong light adsorption ability. • The mechanism of electron transport in these various films photoanodes was proposed.

  12. In situ monitoring the growth of thin-film ZnS/Zn (S,O) bilayer on Cu-chalcopyrite for high performance thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Saez-Araoz, R.; Abou-Ras, D. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Solar Energy Division, Glienicker Strasse 100, 14109 Berlin (Germany); Niesen, T.P. [AVANCIS GmbH and Co KG Otto-Hahn-Ring 6, 81739 Munich (Germany); Neisser, A.; Wilchelmi, K. [SULFURCELL Solartechnik GmbH Barbara-McClintock-Strasse 11, 12489 Berlin (Germany); Lux-Steiner, M.Ch. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Solar Energy Division, Glienicker Strasse 100, 14109 Berlin (Germany); Ennaoui, A. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Solar Energy Division, Glienicker Strasse 100, 14109 Berlin (Germany)], E-mail: ennaoui@helmholtz-berlin.de

    2009-02-02

    This paper highlights the crucial role that the control of the chemical bath deposition (CBD) process plays for buffer production of Cu-chalcopyrite solar-cell devices. ZnS/Zn (S,O) bilayer was deposited on CuInS{sub 2} (CIS) and Cu(In,Ga)(SSe){sub 2} (CIGSSe) and monitored using turbidity measurements of the solution. The results were correlated to the X-ray photoemission spectra of the samples obtained by interruption of the process at sequential stages. Two different feature regimes were distinguished: In the first stage, a heterogeneous reaction takes place on the absorber resulting in the formation of pure ZnS. The second stage of the process is homogeneous, and the in-situ turbidity measurement shows a loss in the transmission of light through the CBD solution. The measured ZnL3M45M45 Auger-peaks, during this second stage of the process, show a shift of the kinetic energy from pure ZnS to a solid-solution ZnS/ZnO ('Zn (S,O)') with decreasing amount of sulfur. These results are supported by the observations from Energy-filtered transmission electron microscopy. This paper also demonstrates that monitoring of the CBD process combined with the basic understanding using surface and interface analysis have contributed to improve the reproducibility and to enhance the photovoltaic performance of Cu-chalcopyrite thin-film solar modules.

  13. In situ monitoring the growth of thin-film ZnS/Zn (S,O) bilayer on Cu-chalcopyrite for high performance thin film solar cells

    International Nuclear Information System (INIS)

    Saez-Araoz, R.; Abou-Ras, D.; Niesen, T.P.; Neisser, A.; Wilchelmi, K.; Lux-Steiner, M.Ch.; Ennaoui, A.

    2009-01-01

    This paper highlights the crucial role that the control of the chemical bath deposition (CBD) process plays for buffer production of Cu-chalcopyrite solar-cell devices. ZnS/Zn (S,O) bilayer was deposited on CuInS 2 (CIS) and Cu(In,Ga)(SSe) 2 (CIGSSe) and monitored using turbidity measurements of the solution. The results were correlated to the X-ray photoemission spectra of the samples obtained by interruption of the process at sequential stages. Two different feature regimes were distinguished: In the first stage, a heterogeneous reaction takes place on the absorber resulting in the formation of pure ZnS. The second stage of the process is homogeneous, and the in-situ turbidity measurement shows a loss in the transmission of light through the CBD solution. The measured ZnL3M45M45 Auger-peaks, during this second stage of the process, show a shift of the kinetic energy from pure ZnS to a solid-solution ZnS/ZnO ('Zn (S,O)') with decreasing amount of sulfur. These results are supported by the observations from Energy-filtered transmission electron microscopy. This paper also demonstrates that monitoring of the CBD process combined with the basic understanding using surface and interface analysis have contributed to improve the reproducibility and to enhance the photovoltaic performance of Cu-chalcopyrite thin-film solar modules

  14. Highly ordered monolayer/bilayer TiO2 hollow sphere films with widely tunable visible-light reflection and absorption bands.

    Science.gov (United States)

    Li, Jie; Qin, Yao; Jin, Chao; Li, Ying; Shi, Donglu; Schmidt-Mende, Lukas; Gan, Lihua; Yang, Jinhu

    2013-06-07

    Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed in depth, combined with some calculations according to Bragg's law. In addition, photocatalytic experiments of RhB degradation employing the THH/THS films as recyclable catalysts have been conducted. The THH/THS films with controlled structures and precisely tunable optical properties are attractive for a wide range of applications, such as recyclable catalysts for photocatalysis, efficient oxide electrodes or scattering layers for solar cells, gas-permeable electrode materials for high-performance sensors and so on.

  15. Low-voltage organic thin film transistors (OTFTs) using crosslinked polyvinyl alcohol (PVA)/neodymium oxide (Nd2O3) bilayer gate dielectrics

    Science.gov (United States)

    Khound, Sagarika; Sarma, Ranjit

    2018-01-01

    We have reported here on the design, processing and dielectric properties of pentacene-based organic thin film transitors (OTFTs) with a bilayer gate dilectrics of crosslinked PVA/Nd2O3 which enables low-voltage organic thin film operations. The dielectric characteristics of PVA/Nd2O3 bilayer films are studied by capacitance-voltage ( C- V) and current-voltage ( I- V) curves in the metal-insulator-metal (MIM) structure. We have analysed the output electrical responses and transfer characteristics of the OTFT devices to determine their performance of OTFT parameters. The mobility of 0.94 cm2/Vs, the threshold voltage of - 2.8 V, the current on-off ratio of 6.2 × 105, the subthreshold slope of 0.61 V/decade are evaluated. Low leakage current of the device is observed from current density-electric field ( J- E) curve. The structure and the morphology of the device are studied using X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. The study demonstrates an effective way to realize low-voltage, high-performance OTFTs at low cost.

  16. Epitaxial growth of Co(0 0 0 1)hcp/Fe(1 1 0)bcc magnetic bi-layer films on SrTiO3(1 1 1) substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

    2008-01-01

    Co(0 0 0 1) hcp /Fe(1 1 0) bcc epitaxial magnetic bi-layer films were successfully prepared on SrTiO 3 (1 1 1) substrates. The crystallographic properties of Co/Fe epitaxial magnetic bi-layer films were investigated. Fe(1 1 0) bcc soft magnetic layer grew epitaxially on SrTiO 3 (1 1 1) substrate with two type variants, Nishiyama-Wasserman and Kurdjumov-Sachs relationships. An hcp-Co single-crystal layer is obtained on Ru(0 0 0 1) hcp interlayer, while hcp-Co layer formed on Au(1 1 1) fcc or Ag(1 1 1) fcc interlayer is strained and may involve fcc-Co phase. It has been shown possible to prepare Co/Fe epitaxial magnetic bi-layer films which can be usable for patterned media application

  17. Highly ordered monolayer/bilayer TiO2 hollow sphere films with widely tunable visible-light reflection and absorption bands

    Science.gov (United States)

    Li, Jie; Qin, Yao; Jin, Chao; Li, Ying; Shi, Donglu; Schmidt-Mende, Lukas; Gan, Lihua; Yang, Jinhu

    2013-05-01

    Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed in depth, combined with some calculations according to Bragg's law. In addition, photocatalytic experiments of RhB degradation employing the THH/THS films as recyclable catalysts have been conducted. The THH/THS films with controlled structures and precisely tunable optical properties are attractive for a wide range of applications, such as recyclable catalysts for photocatalysis, efficient oxide electrodes or scattering layers for solar cells, gas-permeable electrode materials for high-performance sensors and so on.Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed

  18. ZnO piezoelectric film resonator modified with multi-walled carbon nanotubes/polyethyleneimine bilayer for the detection of trace formaldehyde

    Science.gov (United States)

    Ma, Jilong; Wang, Shaotian; Chen, Da; Wang, Wei; Zhang, Zhen; Song, Shuren; Yu, Wenhua

    2018-01-01

    We fabricated a ZnO piezoelectric film resonator modified with multi-walled carbon nanotubes/polyethyleneimine bilayer as the sensitive layer for the detection of trace gaseous formaldehyde. The resonator consists of a ZnO piezoelectric stack and an SiO2/W Bragg reflector. The multi-walled carbon nanotubes were self-assembled on the resonator surface using the n-octadecyl mercaptan monolayer and further modified with polyethyleneimine. The formaldehyde molecules are absorbed on the multi-walled carbon nanotubes/polyethyleneimine bilayer based on the reversible nucleophilic addition reaction between formaldehyde molecules and the amine functional groups on polyethyleneimine. The high working frequency ( 3.1 GHz) of the resonator provided enough mass sensitivity to probe the ultra-small mass change of the sensitive biolayer. The downshift of resonant frequency was linear with the increase of formaldehyde concentration. The experimental results show that our proposed sensor can yield rapid, sensitive, reversible and repeatable responses to formaldehyde in the concentration range of 50-400 ppb at room temperature. The piezoelectric film resonator is a promising and feasible sensor for the indoor pollution monitoring.

  19. Bilayer Phosphorene: Effect of Stacking Order on Bandgap and Its Potential Applications in Thin-Film Solar Cells.

    Science.gov (United States)

    Dai, Jun; Zeng, Xiao Cheng

    2014-04-03

    Phosphorene, a monolayer of black phosphorus, is promising for nanoelectronic applications not only because it is a natural p-type semiconductor but also because it possesses a layer-number-dependent direct bandgap (in the range of 0.3 to 1.5 eV). On basis of the density functional theory calculations, we investigate electronic properties of the bilayer phosphorene with different stacking orders. We find that the direct bandgap of the bilayers can vary from 0.78 to 1.04 eV with three different stacking orders. In addition, a vertical electric field can further reduce the bandgap to 0.56 eV (at the field strength 0.5 V/Å). More importantly, we find that when a monolayer of MoS2 is superimposed with the p-type AA- or AB-stacked bilayer phosphorene, the combined trilayer can be an effective solar-cell material with type-II heterojunction alignment. The power conversion efficiency is predicted to be ∼18 or 16% with AA- or AB-stacked bilayer phosphorene, higher than reported efficiencies of the state-of-the-art trilayer graphene/transition metal dichalcogenide solar cells.

  20. Magnetic properties dependence on the coupled effects of magnetic fields on the microstructure of as-deposited and post-annealed Co/Ni bilayer thin films

    International Nuclear Information System (INIS)

    Franczak, Agnieszka; Levesque, Alexandra; Coïsson, Marco; Li, Donggang; Barrera, Gabriele; Celegato, Federica; Wang, Qiang; Tiberto, Paola; Chopart, Jean-Paul

    2014-01-01

    Magnetic films and multilayers are the focus of much attention motivated mainly by their wide range of applications, such as magnetic data storage devices and sensors. The magnetic multilayer structures are normally prepared through physical means of deposition, as molecular beam epitaxy (MBE) or sputtering. However, there are already examples of materials produced by electrochemical routes, which share with the other deposition techniques a high sensitivity of magnetic and transport properties of the samples on their crystallographic and chemical structure. In addition, electrochemical deposition allows growing structures with high aspect ratio, which are not possible to obtain by MBE deposition followed by lithographic processes. The present work investigates the Co/Ni bilayered nanocrystalline films produced through the temperature-elevated electrochemical deposition, and modified by annealing carried out also under an external magnetic field. The results indicate an increase of the coercive field of deposited Co/Ni bilayers, when the electrodeposition process was conducted under magnetic field of 1 T. The annealing processing caused further remarkable increase of the coercive field of as-prepared bilayers that has been preserved under magnetic annealing conditions. The magnetic properties are discussed in terms of samples microstructure. In as-prepared samples the in-plane magnetization was observed, while high temperature treatment, causing microstructural changes in the film, resulted also in appearance of a small component of magnetization oriented perpendicularly to the films’ plane that could have been observed by MFM analysis. The induced perpendicular magnetization component in the post-annealed samples was a result of the magnetic field applied in the perpendicular direction to the samples’ surface during annealing treatment. - Highlights: • Co deposits were obtained at high electrolyte temperature under applied B-field. • The

  1. Rational design of a bi-layered reduced graphene oxide film on polystyrene foam for solar-driven interfacial water evaporation

    KAUST Repository

    Shi, Le

    2016-12-20

    Solar-driven water evaporation has been emerging as a highly efficient way for utilizing solar energy for clean water production and wastewater treatment. Here we rationally designed and fabricated a bi-layered photothermal membrane with a porous film of reduced graphene oxide (rGO) on the top and polystyrene (PS) foam at the bottom. The top porous rGO layer acts as a light absorber to harvest and convert light efficiently to thermal energy and the bottom PS layer, which purposefully disintegrates water transport channels, acts as an excellent thermal barrier to minimize heat transfer to the nonevaporative bulk water. The optimized bi-layered membrane was able to produce water evaporation rate as high as 1.31 kg m−2 h−1 with light to evaporation conversion efficiency as high as 83%, which makes it a promising photothermal material in the literature. Furthermore, the experiments and theoretical simulation were both conducted to examine the relationship between the overall energy efficiency and the depth of the photothermal material underwater and the experimental and simulations results coincided with each other. Therefore, this work provides systematic evidence in support of the concept of the interfacial heating and shines important light on practical applications of solar-driven processes for clean water production.

  2. Internal flux dynamics and stray field-mediated coupling in the AC susceptibility response of Nb/Ni thin-film bilayers

    Science.gov (United States)

    Badilla, Juan Pablo; Cornejo, Daniel

    2018-03-01

    The in-phase ac magnetic susceptibility (X‧) of Nb/Ni bilayers was measured using a small in-plane magnetic field (the drive field). The sample’s response changes considerably in the presence of perpendicular stray fields that arise during magnetization reversal of the Ni film. The interplay between stray fields and flux lines inside the superconductor is associated to an enhancement of vortex entrance and exit, suggesting an effective magnetic coupling of the ferromagnetic and superconducting components. As a DC field probes the different configurations of the Ni layer throughout its hysteresis loop, the X‧ signal traces a curve with irreversible features that are analogous to those of well-known magnetoresistance measurements. A modification of the measuring temperature provides access to various kinds of superconductor/ferromagnet interaction.

  3. Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors.

    Science.gov (United States)

    Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

    2016-02-25

    In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al₂O₃ and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value.

  4. Formation of a ZnS/Zn(S,O) bilayer buffer on CuInS2 thin film solar cell absorbers by chemical bath deposition

    Science.gov (United States)

    Bär, M.; Ennaoui, A.; Klaer, J.; Kropp, T.; Sáez-Araoz, R.; Allsop, N.; Lauermann, I.; Schock, H.-W.; Lux-Steiner, M. C.

    2006-06-01

    The application of Zn compounds as buffer layers was recently extended to wide-gap CuInS2 (CIS) based thin film solar cells. Using an alternative chemical deposition route for the buffer preparation aiming at the deposition of a single-layer, nominal ZnS buffer without the need for any toxic reactants such as hydrazine has helped us to achieve a similar efficiency as respective CdS-buffered reference devices. In order to shed light on the differences of other Zn-compound buffers deposited in conventional chemical baths [chemical bath deposition (CBD)] compared to the buffer layers deposited by this alternative CBD process, the composition of the deposited buffers was investigated by x-ray excited Auger electron and x-ray photoelectron spectroscopy to potentially clarify their superiority in terms of device performance. We have found that in the early stages of this alternative CBD process a thin ZnS layer is formed on the CIS, whereas in the second half of the CBD the growth rate is greatly increased and Zn(S,O) with a ZnS/(ZnS+ZnO) ratio of ~80% is deposited. Thus, a ZnS/Zn(S,O) bilayer buffer is deposited on the CIS thin film solar cell absorbers by the alternative chemical deposition route used in this investigation. No major changes of these findings after a postannealing of the buffer/CIS sample series and recharacterization could be identified.

  5. MAX phase formation by intercalation upon annealing of TiCx/Al (0.4 ≤ x ≤ 1) bilayer thin films

    International Nuclear Information System (INIS)

    Abdulkadhim, Ahmed; Takahashi, Tetsuya; Music, Denis; Munnik, Frans; Schneider, Jochen M.

    2011-01-01

    TiC x /Al bilayer thin films were synthesized using combinatorial magnetron sputtering to study the influence of C content on the reaction products at different annealing temperatures. Based on energy-dispersive X-ray analysis calibrated by elastic recoil detection analysis data, x in TiC x was varied from 0.4 to 1.0. Film constitution was studied by X-ray diffraction before and after annealing at temperatures from 500 to 1000 deg. C. The formation of TiC x and Al in the as-deposited samples over the whole C/Ti range was identified. Upon annealing, TiC x reacts with Al to form Ti-Al-based intermetallics. At temperatures as low as 700 deg. C, the formation of MAX phases (space group P6 3 /mmc) is observed at x ≤ 0.7. Based on the comparison between the C content induced changes in the lattice spacing of TiC x and Ti 2 AlC as well as Ti 3 AlC 2 , we infer the direct formation of MAX phases by Al intercalation into TiC x for x ≤ 0.7.

  6. Enhanced magnetoelectric response in 2-2 bilayer 0.50Pb(Ni1/3Nb2/3)O3–0.35PbTiO3–0.15PbZrO3/NiFe2O4 thin films

    Science.gov (United States)

    Ade, Ramesh; Sambasiva, V.; Kolte, Jayant; Karthik, T.; Kulkarni, Ajit R.; Venkataramani, N.

    2018-03-01

    In this work, room temperature magnetoelectric (ME) properties of 0.50Pb(Ni1/3Nb2/3)O3–0.35PbTiO3–0.15PbZrO3 (PNNZT)/NiFe2O4 (NFO) 2-2 bilayer thin films grown on Pt/Ti/SiO2/Si substrate, using pulsed laser deposition technique, are reported. Structural studies confirm single phase PNNZT/NFO 2-2 bilayer structure formation. PNNZT/NFO 2-2 bilayer thin film shows a maximum ME voltage coefficient (α E ) of ~0.70 V cm‑1. Oe–1 at a frequency of 1 kHz. The present study reveals that PNNZT/NFO bilayer thin film can be a potential candidate for technological applications.

  7. Ferroelectric properties of BaTiO3/PbZr0.2Ti.08O3 bilayer thin film

    Science.gov (United States)

    Salev, Pavel; Yang, Chun; Grigoriev, Alexei

    2014-03-01

    The thin film ferroelectric BaTiO3/PbZr0.2Ti0.8O3 bilayer was epitaxially grown on SrRuO3/SrTiO3 substrate by RF sputtering. Electrical measurements of polarization switching revealed two different switching regimes - a small ferroelectric hysteresis loop at low applied voltage and a larger loop at a high voltage. The measured dielectric permittivity corresponds to weak electrostatic coupling between two layers according to Landau-Ginsburg-Devonshire theory. This weak coupling may allow for independent polarization states to exist in individual layers. This can lead to stable head-to-head and tail-to-tail polarization domain configurations, which would explain the two switching regimes observed in electrical measurements. The compensation of polarization gradient across the interface can be explained by the enhancement of interface charge carrier density due to strong bending of electron energy bands. This work was supported by NSF award DMR-1057159.

  8. Effect of swift heavy ion irradiation on structural and opto-electrical properties of bi-layer CdS-Bi2S3 thin films prepared by solution growth technique at room temperature

    Science.gov (United States)

    Shaikh, Shaheed U.; Siddiqui, Farha Y.; Desale, Deepali J.; Ghule, Anil V.; Singh, Fouran; Kulriya, Pawan K.; Sharma, Ramphal

    2015-01-01

    CdS-Bi2S3 bi-layer thin films have been deposited by chemical bath deposition method on Indium Tin Oxide glass substrate at room temperature. The as-deposited thin films were annealed at 250 °C in an air atmosphere for 1 h. An air annealed thin film was irradiated using Au9+ ions with the energy of 120 MeV at fluence 5×1012 ions/cm2 using tandem pelletron accelerator. The irradiation induced modifications were studied using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Raman spectroscopy, UV spectroscopy and I-V characteristics. XRD study reveals that the as-deposited thin films were nanocrystalline in nature. The decrease in crystallite size, increase in energy band gap and resistivity were observed after irradiation. Results are explained on the basis of energy deposited by the electronic loss after irradiation. The comparative results of as-deposited, air annealed and irradiated CdS-Bi2S3 bi-layer thin films are presented.

  9. Intermixing at the heterointerface between ZnS /Zn(S,O) bilayer buffer and CuInS2 thin film solar cell absorber

    Science.gov (United States)

    Bär, M.; Ennaoui, A.; Klaer, J.; Kropp, T.; Sáez-Araoz, R.; Lehmann, S.; Grimm, A.; Lauermann, I.; Loreck, Ch.; Sokoll, St.; Schock, H.-W.; Fischer, Ch.-H.; Lux-Steiner, M. C.; Jung, Ch.

    2006-09-01

    The application of Zn compounds as buffer layers was recently extended to wide-gap CuInS2 (CIS) based thin-film solar cells. Using an alternative chemical deposition route for the buffer preparation aiming at the deposition of a single-layer, nominal ZnS buffer without the need for any toxic reactants such as hydrazine has helped us to achieve a similar efficiency as respective CdS-buffered reference devices. After identifying the deposited Zn compound, as ZnS /Zn(S,O) bilayer buffer in former investigations [M. Bär et al., J. Appl. Phys. 99, 123503 (2006)], this time the focus lies on potential diffusion/intermixing processes at the buffer/absorber interface possibly, clarifying the effect of the heat treatment, which drastically enhances the device performance of respective final solar cells. The interface formation was investigated by x-ray photoelectron and x-ray excited Auger electron spectroscopy. In addition, photoelectron spectroscopy (PES) measurements were also conducted using tunable monochromatized synchrotron radiation in order to gain depth-resolved information. The buffer side of the buffer/absorber heterointerface was investigated by means of the characterization of Zn(S ,O)/ZnS/CIS structures where the ZnS /Zn(S,O) bilayer buffer was deposited successively by different deposition times. In order to make the (in terms of PES information depth) deeply buried absorber side of the buffer/absorber heterointerface accessible for characterization, in these cases the buffer layer was etched away by dilute HClaq. We found indications that while (out-leached) Cu from the absorber layer forms together with the educts in the chemical bath a [Zn(1-Z ),Cu2Z]S-like interlayer between buffer and absorber, Zn is incorporated in the uppermost region of the absorber. Both effects are strongly enhanced by postannealing the Zn(S ,O)/ZnS/CIS samples. However, it was determined that the major fraction of the Cu and Zn can be found quite close to the heterointerface in

  10. Pulsed laser deposition of epitaxial Sr(RuxSn1-x)O3 thin film electrodes and KNbO3/Sr(RuxSn1-x)O3 bilayers

    International Nuclear Information System (INIS)

    Christen, H.M.; Boatner, L.A.; English, L.Q.; Geea, L.A.; Marrero, P.J.; Norton, D.P.

    1995-01-01

    Sr(Ru x Sn 1-x ) 3 is proposed as a new conducting oxide for use in epitaxial multilayer structures. The Sr(Ru o 48 Sn 0.52 )0 3 composition exhibits an excellent lattice match with (100)-oriented KTaO 3 , and films of this composition grown by pulsed laser deposition on KTaO 3 , SrTiO 3 , and LaAlO 3 substrates have been analyzed by X-ray diffraction, Rutherford backscattering/ion channeling, and resistivity measurements. Epitaxial KNbO 3 /Sr(Ru 0.48 Sn 0.52 )O 3 bilayers have been successfully grown

  11. Lipid Bilayer Formation on Organic Electronic Materials

    KAUST Repository

    Zhang, Yi

    2018-04-23

    The lipid bilayer is the elemental structure of cell membrane, forming a stable barrier between the interior and exterior of the cell while hosting membrane proteins that enable selective transport of biologically important compounds and cellular recognition. Monitoring the quality and function of lipid bilayers is thus essential and can be performed using electrically active substrates that allow for transduction of signals. Such a promising electronic transducer material is the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) which has provided a plethora of novel bio transducing architectures. The challenge is however in assembling a bilayer on the conducting polymer surface, which is defect-free and has high mobility. Herein, we investigate the fusion of zwitterionic vesicles on a variety of PEDOT:PSS films, but also on an electron transporting, negatively charged organic semiconductor, in order to understand the surface properties that trigger vesicle fusion. The PEDOT:PSS films are prepared from dispersions containing different concentrations of ethylene glycol included as a formulation additive, which gives a handle to modulate surface physicochemical properties without a compromise on the chemical composition. The strong correlation between the polarity of the surface, the fusion of vesicles and the mobility of the resulting bilayer aides extracting design principles for the development of future conducting polymers that will enable the formation of lipid bilayers.

  12. Self-folding graphene-polymer bilayers

    International Nuclear Information System (INIS)

    Deng, Tao; Yoon, ChangKyu; Jin, Qianru; Li, Mingen; Liu, Zewen; Gracias, David H.

    2015-01-01

    In order to incorporate the extraordinary intrinsic thermal, electrical, mechanical, and optical properties of graphene with three dimensional (3D) flexible substrates, we introduce a solvent-driven self-folding approach using graphene-polymer bilayers. A polymer (SU-8) film was spin coated atop chemically vapor deposited graphene films on wafer substrates and graphene-polymer bilayers were patterned with or without metal electrodes using photolithography, thin film deposition, and etching. After patterning, the bilayers were released from the substrates and they self-folded to form fully integrated, curved, and folded structures. In contrast to planar graphene sensors on rigid substrates, we assembled curved and folded sensors that are flexible and they feature smaller form factors due to their 3D geometry and large surface areas due to their multiple rolled architectures. We believe that this approach could be used to assemble a range of high performance 3D electronic and optical devices of relevance to sensing, diagnostics, wearables, and energy harvesting

  13. Enhanced performance of Au/P3HT/ (bilayer dielectrics)/Si thin-film-transistor having gold nanoparticles chemically bonded to P3HT.

    Science.gov (United States)

    Wong, Mon-Chi; Yeh, Shin-Chi; Chiu, Li-Ko; Chen, Yen-Heng; Ho, Jeng-Rong; Tsiang, Raymond Chien-Chao

    2012-03-01

    The charge transport enhancement of using poly(3-hexylthiophene) covalently bonded with gold nanoparticles as an active layer in a bottom-gate/top contact, Au/(P3HT)/(bilayer dielectric)/Si OTFT device has been studied. P3HT was synthesized via the modified Grignard metathesis method and functionalized to have a thiol terminal (P3HT(SH)). Gold nanoparticles (AuNPs) with sizes ranging from 2 to 10 nm were then formed via a reduction of HAuCl4 in the presence of P3HT(SH). Compared to the pristine P3HT, the AuNPs-containing P3HT composite materials have a higher energy level of HOMO and a smaller electrochemical bandgap E(g)chem. The smaller bandgap enhances the charge carrier mobility and the higher HOMO energy level indicates a reduced barrier and an increased injection rate for charge carrier at the source contact. Furthermore, the threshold voltage V(T) of AuNPs-containing P3HT samples remain nearly unchanged and their saturation current I(D) and the field-effect mobility are higher. An OTFT device fabricated with a composite sample containing 1.30% AuNPs has a carrier mobility and saturation current nearly two time higher than pristine P3HT.

  14. Anomalous Hall effect in Fe/Gd bilayers

    KAUST Repository

    Xu, W. J.

    2010-04-01

    Non-monotonic dependence of anomalous Hall resistivity on temperature and magnetization, including a sign change, was observed in Fe/Gd bilayers. To understand the intriguing observations, we fabricated the Fe/Gd bilayers and single layers of Fe and Gd simultaneously. The temperature and field dependences of longitudinal resistivity, Hall resistivity and magnetization in these films have also been carefully measured. The analysis of these data reveals that these intriguing features are due to the opposite signs of Hall resistivity/or spin polarization and different Curie temperatures of Fe and Gd single-layer films. Copyright (C) EPLA, 2010

  15. Light-driven formation and rupture of droplet bilayers.

    Science.gov (United States)

    Dixit, Sanhita S; Kim, Hanyoup; Vasilyev, Arseny; Eid, Aya; Faris, Gregory W

    2010-05-04

    We demonstrate the optical manipulation of nanoliter aqueous droplets containing surfactant or lipid molecules and immersed in an organic liquid using near-infrared light. The resulting emulsion droplets are manipulated using both the thermocapillary effect and convective fluid motion. Droplet-pair interactions induced in the emulsion upon optical initiation and control provide direct observations of the coalescence steps in intricate detail. Droplet-droplet adhesion (bilayer formation) is observed under several conditions. Selective bilayer rupture is also realized using the same infrared laser. The technique provides a novel approach to studying thin film drainage and interface stability in emulsion dynamics. The formation of stable lipid bilayers at the adhesion interface between interacting water droplets can provide an optical platform on which to build droplet-based lipid bilayer assays. The technique also has relevance to understanding and improving microfluidics applications by devising Petri dish-based droplet assays requiring no substrate fabrication.

  16. Ion beam mixing isotopic metal bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  17. Intermixing at the heterointerface between ZnS Zn S,O bilayer buffer and CuInS2 thin film solar cell absorber

    OpenAIRE

    Bär, M.; Ennaoui, A.; Klaer, J.; Kropp, T.; S ez Araoz, R.; Lehmann, S.; Grimm, A.; Lauermann, I.; Loreck, Ch.; Sokoll, St.; Schock, H. W.; Fischer, Ch. H.; Lux Steiner, M.C.; Jung, Ch

    2006-01-01

    The application of Zn compounds as buffer layers was recently extended to wide gap CuInS2 CIS based thin film solar cells. Using a new chemical deposition route for the buffer preparation aiming at the deposition of a single layer, nominal ZnS buffer without the need for any toxic reactants such as, e.g. hydrazine has helped to achieve a similar efficiency as respective CdS buffered reference devices. After identifying the deposited Zn compound, as ZnS Zn S,O bi layer buffer in former in...

  18. Formation of a ZnS Zn S,O bilayer buffer on CuInS2 thin film solar cell absorbers by chemical bath deposition

    OpenAIRE

    Bär, M.; Ennaoui, A.; Klaer, J.; Kropp, T.; S ez Araoz, R.; Allsop, N.; Lauermann, I.; Schock, H. W.; Lux Steiner, M.C

    2006-01-01

    The application of Zn compounds as buffer layers was recently extended to wide gap CuInS2 CIS based thin film solar cells. Using a new chemical deposition route for the buffer preparation aiming at the deposition of a single layer, nominal ZnS buffer without the need for any toxic reactants such as, e.g. hydrazine, has helped to achieve a similar efficiency as respective CdS buffered reference devices. In order to shed light on the differences of other Zn compound buffers deposited in con...

  19. Synthesis of Homogenous Bilayer Graphene on Industrial Cu Foil

    Science.gov (United States)

    Luo, Wen-Gang; Wang, Hua-Feng; Cai, Kai-Ming; Han, Wen-Peng; Tan, Ping-Heng; Hu, Ping-An; Wang, Kai-You

    2014-06-01

    We synthesize the homogenous graphene films on cheap industrial Cu foils using low pressure chemical vapor deposition. The quality and the number of layers of graphene are characterized by Raman spectra. Through carefully tuning the growth parameters, we find that the growth temperature, hydrocarbon concentration and the growth time can substantially affect the growth of high-quality graphene. Both single and bilayer large size homogenous graphenes have been synthesized in optimized growth conditions. The growth of graphene on Cu surface is found to be self ceasing in the bilayer graphene process with the low solubility of carbon in Cu. Furthermore, we have optimized the transfer process, and clear graphene films almost free from impurity are successfully transferred onto Si/SiO2 substrates. The field effect transistors of bilayer graphene are fabricated, which demonstrates a maximum hole (electron) mobility of 4300 cm2 V-1s-1 (1920 cm2V-1s-1) at room temperature.

  20. A simple method to tune graphene growth between monolayer and bilayer

    Directory of Open Access Journals (Sweden)

    Xiaozhi Xu

    2016-02-01

    Full Text Available Selective growth of either monolayer or bilayer graphene is of great importance. We developed a method to readily tune large area graphene growth from complete monolayer to complete bilayer. In an ambient pressure chemical vapor deposition process, we used the sample temperature at which to start the H2 flow as the control parameter and realized the change from monolayer to bilayer growth of graphene on Cu foil. When the H2 starting temperature was above 700°C, continuous monolayer graphene films were obtained. When the H2 starting temperature was below 350°C, continuous bilayer films were obtained. Detailed characterization of the samples treated under various conditions revealed that heating without the H2 flow caused Cu oxidation. The more the Cu substrate oxidized, the less graphene bilayer could form.

  1. Pedot and PPy Conducting Polymer Bilayer and Trilayer Actuators

    DEFF Research Database (Denmark)

    Zainudeen, Umer Lebbe; Careem, Mohamed Abdul; Skaarup, Steen

    2008-01-01

    attempts have been made to improve the actuator performance. We report electromechanical measurements on actuators of bilayer and trilayer free standing films prepared with polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers. Both types of conducting polymer are pre...

  2. Tungsten Trioxide/Zinc Tungstate Bilayers: Electrochromic Behaviors, Energy Storage and Electron Transfer

    International Nuclear Information System (INIS)

    Wei, Huige; Ding, Daowei; Yan, Xingru; Guo, Jiang; Shao, Lu; Chen, Haoran; Sun, Luyi; Colorado, Henry A.; Wei, Suying; Guo, Zhanhu

    2014-01-01

    Highlights: • Tungsten oxide and zinc tungstate bilayers have been prepared via a facile sol-gel method for integrated applications of electrochromic behaviors and energy storage;. • Electron transfer behaviors between the semiconductor bilayer films have been found dependent on the bilayer assembly sequence;. • Methylene blue (MB) has been employed for the first time as an indicator to study the electron transfer phenomenon in the bilayer films. - Abstract: Pair-sequentially spin-coated tungsten trioxide (WO 3 ) and zinc tungstate (ZnWO 4 ) bilayer films onto indium tin oxide (ITO) coated glass slides have been prepared via sol-gel methods followed by annealing. The bilayers (ZnWO 4 /WO 3 denoting the bilayer film with the inner layer of ZnWO 4 and the outer layer of WO 3 on the ITO while WO 3 /ZnWO 4 standing for the bilayer film with the inner layer of WO 3 and the outer layer of ZnWO 4 on the ITO) exhibit integrated functions of electrochromic and energy storage behaviors as indicated by the in situ spectroelectrochemistry and cyclic voltammetry (CV) results. Accordingly, blue color was observed for the bilayer films at -1 V in 0.5 M H 2 SO 4 solution. An areal capacitance of 140 and 230 μF/cm 2 was obtained for the ZnWO 4 /WO 3 , and WO 3 /ZnWO 4 film, respectively, at a scan rate of 0.05 V/s in the CV measurements. The CV results also unveiled the electron transfer behavior between the semiconductor films in the oxidation process, suggesting a sequence-dependent electrochemical response in the bilayer films. Meanwhile, methylene blue (MB) was used as an indicator to study the electron transfer phenomenon during the reduction process at negative potentials of -0.4 and -0.8 V, in 0.5 M Na 2 SO 4 . The results indicated that the electrons transfer across the bilayers was enhanced at more negative potentials

  3. 100-nm-sized magnetic domain reversal by the magneto-electric effect in self-assembled BiFeO3/CoFe2O4 bilayer films

    OpenAIRE

    Keita Sone; Hiroshi Naganuma; Masaki Ito; Takamichi Miyazaki; Takashi Nakajima; Soichiro Okamura

    2015-01-01

    A (001)-epitaxial-BiFeO3/CoFe2O4 bilayer was grown by self-assembly on SrTiO3 (100) substrates by just coating a mixture precursor solution. The thickness ratio of the bilayer could be controlled by adjusting the composition ratio. For example, a BiFeOx:CoFe2Ox = 4:1 (namely Bi4CoFe6Ox) mixture solution could make a total thickness of 110nm divided into 85-nm-thick BiFeO3 and 25-nm-thick CoFe2O4. Self-assembly of the bilayer occurred because the perovskite BiFeO3 better matched the lattice co...

  4. Approaches toward functional fluid supported lipid bilayers

    Science.gov (United States)

    Weng, Kevin Chun-I.

    Planar supported lipid bilayers (PSLBs) have attracted immense interest for their properties as model cell membranes and for potential applications in biosensors and lab-on-a-chip devices. Our study covers three aspects of the construction, characterization, and application of functional PSLBs. First, a combination of micro-fabrication, the Langmuir-Blodgett (LB) technique, and fusion of extruded small unilamellar vesicle (E-SUVs) in sequence was used to create polymer-cushioned PSLBs in a microarray format. Random lipo-glycocopolymer mixed with L-alpha-phosphatidylcholine (egg PC) was compressed at the air-water interface and transferred onto the photoresist-patterned substrate by the LB technique to achieve spatially directed deposition. Construction of planar bilayers in an aqueous environment was subsequently completed by vesicle fusion. Epifluorescence microscopy, fluorescence recovery after photobleaching (FRAP), and electrophoresis-relaxation were employed to examine the resulting patterns as well as to verify the two-dimensional mobility of the supported membrane systems. This approach could possibly provide a useful route to create functional arrays of polymer-supported lipid bilayers. Second, we report the formation of fluid planar biomembranes on hydrophilic silica aerogels and xerogels. When the aerogel/xerogel was pre-hydrated and then allowed to incubate in egg PC E-SUV solution, lipid bilayers were formed due to the favorable interaction of vesicles with the hydroxyl-abundant silica surface. FRAP was used to determine the lateral diffusivity of membranes on aerogels. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to monitor the kinetics of the irreversible adsorption and fusion of vesicles into bilayers on xerogel thin films. Finally, we compared the formation of PSLBs with and without incorporation of monosialoganglioside GM1 (GM1) as the antigen for in situ antibody binding. Quantifiable differences were observed in the

  5. Polarization modulation infrared reflection absorption spectroscopy investigations of thin silica films deposited on gold. 2. Structural analysis of a 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayer.

    Science.gov (United States)

    Zawisza, Izabella; Wittstock, Gunther; Boukherroub, Rabah; Szunerits, Sabine

    2008-04-15

    In this paper we report on the structural analysis of bilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) using polarization modulation infrared reflection absorption spectroscopy (PM IRRAS). The lipid bilayers were formed on SiO2|Au and Au surfaces using the Langmuir-Blodgett and Langmuir-Schaeffer techniques. As we showed in part 1 (Zawisza, I.; Wittstock, G.; Boukherroub, R.; Szunertis, S. Langmuir 2007, 23, 9303-9309), SiO2 layers of 7 nm thickness, synthesized by plasma-enhanced chemical vapor deposition on 200 nm thick gold covered glass slides, allow PM IRRAS investigations. Only minor changes in the order and structure of the lipid bilayer are observed when deposited on SiO2|Au and Au surfaces. The choline moiety in the leaflet directed toward the SiO2 surface exists in trans conformation and shows a tilt of 28 degrees with the surface normal of the CN bond. On the silica surface in the second leaflet directed toward air and in two layers deposited on the Au surface, trans and gauche isomers of the choline moiety are present and the tilt of the CN bond increases to 55 degrees with respect to the surface normal. The order and molecular orientation in the DMPC bilayers on SiO2 and Au surfaces are not affected by time. The analysis of the phosphate stretching mode on the Au surface shows slight dehydration of this group and reorientation of the phosphate moiety.

  6. 100-nm-sized magnetic domain reversal by the magneto-electric effect in self-assembled BiFeO3/CoFe2O4 bilayer films

    Science.gov (United States)

    Sone, Keita; Naganuma, Hiroshi; Ito, Masaki; Miyazaki, Takamichi; Nakajima, Takashi; Okamura, Soichiro

    2015-04-01

    A (001)-epitaxial-BiFeO3/CoFe2O4 bilayer was grown by self-assembly on SrTiO3 (100) substrates by just coating a mixture precursor solution. The thickness ratio of the bilayer could be controlled by adjusting the composition ratio. For example, a BiFeOx:CoFe2Ox = 4:1 (namely Bi4CoFe6Ox) mixture solution could make a total thickness of 110nm divided into 85-nm-thick BiFeO3 and 25-nm-thick CoFe2O4. Self-assembly of the bilayer occurred because the perovskite BiFeO3 better matched the lattice constant (misfit approximately 1%) and crystal symmetry of the perovskite SrTiO3 than the spinel CoFe2O4 (misfit approximately 7%). The magnetic domains of the hard magnet CoFe2O4 were switched by the polarization change of BiFeO3 due to an applied vertical voltage, and the switched magnetic domain size was approximately 100nm in diameter. These results suggest that self-assembled BiFeO3/CoFe2O4 bilayers are interesting in voltage driven nonvolatile memory with a low manufacturing cost.

  7. PBCO/YBCO bilayer growth and optimization for the fabrication of buffered step-edge Josephson junctions

    CSIR Research Space (South Africa)

    Van Staden, WF

    2009-04-01

    Full Text Available Bilayers of PBCO and YBCO are grown epitaxially on MgO substrates using PLD. In this paper, researchers discuss the entire optimization process in detail, giving quantitative parameter values. Film characterization included XRD, AFM and susceptance...

  8. Film

    OpenAIRE

    Jones, Sarah

    2002-01-01

    This book looks at the movie industry and at the labour intensive but fascinating process of making a feature film. It examines each stage in the production of a film, from initial idea through to the final cut and screening, and highlights the main activities that take place along the way. The book not only looks at the work of prominent people in the film world, such as directors and actors, but also describes the equally important but less high profile contributions of the gaffer, best boy...

  9. Film

    OpenAIRE

    Bould, M.

    2014-01-01

    A critical overview of critical-theoretical understandings of sf film, especially those promulgated by critics devoted to sf as a prose fiction form. It also considers adaptation, spectacle and special effects.

  10. Magnetic properties of epitaxial bismuth ferrite-garnet mono- and bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Semuk, E.Yu.; Berzhansky, V.N.; Prokopov, A.R.; Shaposhnikov, A.N.; Karavainikov, A.V. [Taurida National V.I. Vernadsky University, Vernadsky Avenue, 4, 95007 Simferopol (Ukraine); Salyuk, O.Yu. [Institute of Magnetism NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine); Golub, V.O., E-mail: golub@imag.kiev.ua [Institute of Magnetism NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine)

    2015-11-15

    Magnetic properties of Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} (84 nm) and Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} (180 nm) films epitaxially grown on gallium-gadolinium garnet (GGG) single crystal (111) substrate as well as Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} bilayer were investigated using ferromagnetic resonance technique. The mismatch of the lattice parameters of substrate and magnetic layers leads to formation of adaptive layers which affect on the high order anisotropy constant of the films but practically do not affect on uniaxial perpendicular magnetic anisotropy The magnetic properties of the bilayer film were explained in supposition of strong exchange coupling between magnetic layers taking into account film-film and film-substrate elastic interaction. - Highlights: • Magnetic parameters of epitaxial Bi-YIG films and bilayers on GGG substrate. • Adaptive layers affect on high order magnetic anisotropy. • Magnetic properties of bilayers are result of strong exchange interaction.

  11. Magnetic properties of epitaxial bismuth ferrite-garnet mono- and bilayers

    International Nuclear Information System (INIS)

    Semuk, E.Yu.; Berzhansky, V.N.; Prokopov, A.R.; Shaposhnikov, A.N.; Karavainikov, A.V.; Salyuk, O.Yu.; Golub, V.O.

    2015-01-01

    Magnetic properties of Bi 1.5 Gd 1.5 Fe 4.5 Al 0.5 O 12 (84 nm) and Bi 2.8 Y 0.2 Fe 5 O 12 (180 nm) films epitaxially grown on gallium-gadolinium garnet (GGG) single crystal (111) substrate as well as Bi 1.5 Gd 1.5 Fe 4.5 Al 0.5 O 12 /Bi 2.8 Y 0.2 Fe 5 O 12 bilayer were investigated using ferromagnetic resonance technique. The mismatch of the lattice parameters of substrate and magnetic layers leads to formation of adaptive layers which affect on the high order anisotropy constant of the films but practically do not affect on uniaxial perpendicular magnetic anisotropy The magnetic properties of the bilayer film were explained in supposition of strong exchange coupling between magnetic layers taking into account film-film and film-substrate elastic interaction. - Highlights: • Magnetic parameters of epitaxial Bi-YIG films and bilayers on GGG substrate. • Adaptive layers affect on high order magnetic anisotropy. • Magnetic properties of bilayers are result of strong exchange interaction

  12. Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids – a QCM-D and AFM Study

    Directory of Open Access Journals (Sweden)

    Kervin O. Evans

    2008-04-01

    Full Text Available Quartz crystal microbalance with dissipation (QCM-D monitoring and atomic force microscopy (AFM were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM+ was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonylimide (Tf2N- was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonylimide (BMP-Tf2N formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer.

  13. Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids – a QCM-D and AFM Study †

    Science.gov (United States)

    Evans, Kervin O.

    2008-01-01

    Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM+) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf2N-) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-Tf2N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer. PMID:19325765

  14. Super-Sensitive and Robust Biosensors from Supported Polymer Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, Walter F. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Biological organisms are potentially the most sensitive and selective biological detection systems known, yet we are currently severely limited in our ability to exploit biological interactions in sensory devices, due in part to the limited stability of biological systems and derived materials. This proposal addresses an important aspect of integrating biological sensory materials in a solid state device. If successful, such technology could enable entirely new classes of robust biosensors that could be miniaturized and deployed in the field. The critical aims of the proposed work were 1) the calibration of a more versatile approach to measuring pH, 2) the use of this method to monitor pH changes caused by the light-induced pumping of protons across vesicles with bacteriorhodopsin integrated into the membranes (either polymer or lipid); 3) the preparation of bilayer assemblies on platinum surfaces; 4) the enhanced detection of lightinduced pH changes driven by bR-loaded supported bilayers. I have developed a methodology that may enable that at interfaces and developed a methodology to characterize the functionality of bilayer membranes with reconstituted membrane proteins. The integrity of the supported bilayer films however must be optimized prior to the full realization of the work originally envisioned in the original proposal. Nevertheless, the work performed on this project and the encouraging results it has produced has demonstrated that these goals are challenging yet within reach.

  15. Optical, electrical and thermoelectric power studies of Al–Sb thin film ...

    Indian Academy of Sciences (India)

    Unknown

    been made to study the bilayer diffusion properties of Al–. Sb thin films. In the present communication, RBS analysis, optical, electrical and thermoelectric power studies of Al–. Sb bilayer structure of thin films prepared by thermal co- evaporation technique is reported. 2. Experimental. Aluminium antimonide films were ...

  16. Thickness Effect on F8T2/C60 Bilayer Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Natasha A. D. Yamamoto

    2012-01-01

    Full Text Available Copolymers based on fluorene-thiophene units have presented promising efficiencies in photovoltaic devices applications. They present good transport properties mainly after thermal treatment of the polymer films. Here, we investigate the properties of bilayer devices formed by the heterojunction of the polymer F8T2 with variable thickness and the fullerene. The series resistance of the equivalent circuit associated with the device increases as the polymer film gets thicker. The current-voltage characteristics of the bilayer devices follow the Mott-Gurney law of SCLC. For the best performing device we measured 2.1% of power conversion efficiency.

  17. Alcohol Interactions with Lipid Bilayers

    Directory of Open Access Journals (Sweden)

    Tomáš Kondela

    2017-11-01

    Full Text Available We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohol’s membrane-water partitioning. We have observed clear changes to membrane structure in both transversal and lateral directions. Most importantly, our results suggest the alteration of the membrane-water interface. The water encroachment has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The experimental results have been corroborated by molecular dynamics simulations to reveal further details. Namely, the order parameter profiles have been fruitful in correlating the mechanical model of structural changes to the effect of anesthesia.

  18. Electrodeless QCM-D for lipid bilayer applications.

    Science.gov (United States)

    Kunze, Angelika; Zäch, Michael; Svedhem, Sofia; Kasemo, Bengt

    2011-01-15

    An electrodeless quartz crystal microbalance with dissipation monitoring (QCM-D) setup is used to monitor the formation of supported lipid bilayers (SLBs) on bare quartz crystal sensor surfaces. The kinetic behavior of the formation of a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) SLB on SiO(2) surfaces is discussed and compared for three cases: (i) a standard SiO(2) film deposited onto the gold electrode of a quartz crystal, (ii) an electrodeless quartz crystal with a sputter-coated SiO(2) film, and (iii) an uncoated electrodeless quartz crystal sensor surface. We demonstrate, supported by imaging the SLB on an uncoated electrodeless surface using atomic force microscopy (AFM), that a defect-free, completely covering bilayer is formed in all three cases. Differences in the kinetics of the SLB formation on the different sensor surfaces are attributed to differences in surface roughness. The latter assumption is supported by imaging the different surfaces using AFM. We show furthermore that electrodeless quartz crystal sensors can be used not only for the formation of neutral SLBs but also for positively and negatively charged SLBs. Based on our results we propose electrodeless QCM-D to be a valuable technique for lipid bilayer and related applications providing several advantages compared to electrode-coated surfaces like optical transparency, longer lifetime, and reduced costs. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Phase diagram of the CF₄ monolayer and bilayer on graphite.

    Science.gov (United States)

    Thomas, Petros; Hess, George B

    2014-05-21

    We report an experimental study of physisorbed monolayers and bilayers of CF4 on graphite using infrared reflection absorption spectroscopy supplemented by ellipsometry. The symmetric C-F stretch mode ν3 near 1283 cm(-1) in the gas is strongly blue shifted in the film by dynamic dipole coupling. This blue shift provides a very sensitive measure of the inter-molecular spacing in the monolayer and, less directly, in the bilayer. We find that important corrections are necessary to the volumetric coverage scales used in previous heat capacity and x-ray diffraction studies of this system. This requires quantitative and some qualitative changes to the previously proposed phase diagram. We find evidence for a new phase transition in the middle of the hexagonal incommensurate region and construct new phase diagrams in both the variables coverage-temperature and chemical potential-temperature. We determine the compressibility and thermal expansion in the low-pressure hexagonal incommensurate phase and values for the entropy change in several phase transitions. Below about 55 K there is evidence of solution of up to 7% of an impurity, most likely CO, in our monolayer but not the bilayer film.

  20. Film

    OpenAIRE

    Balint, Ruth; Dolgopolov, Greg

    2008-01-01

    From the beginning of the twentieth century, Sydney defined cosmopolitanism and modernity in the national imagination, and central to this image was the cinema: its technology, its architecture, its stars, its marketing and the stories it circulated to its audiences about Australia and the world. Though it is difficult to define a genre of Sydney film, Sydney provided the backdrop for a host of ideas about the city, and later suburbia. Sydney came to be seen as a ‘tinsel town’ of cultural ban...

  1. Minimal Bending Energies of Bilayer Polyhedra

    Science.gov (United States)

    Haselwandter, Christoph A.; Phillips, Rob

    2011-01-01

    Motivated by recent experiments on bilayer polyhedra composed of amphiphilic molecules, we study the elastic bending energies of bilayer vesicles forming polyhedral shapes. Allowing for segregation of excess amphiphiles along the ridges of polyhedra, we find that bilayer polyhedra can indeed have lower bending energies than spherical bilayer vesicles. However, our analysis also implies that, contrary to what has been suggested on the basis of experiments, the snub dodecahedron, rather than the icosahedron, generally represents the energetically favorable shape of bilayer polyhedra. PMID:21231425

  2. Texture of lipid bilayer domains

    DEFF Research Database (Denmark)

    Jensen, Uffe Bernchou; Brewer, Jonathan R.; Midtiby, Henrik Skov

    2009-01-01

    We investigate the texture of gel (g) domains in binary lipid membranes composed of the phospholipids DPPC and DOPC. Lateral organization of lipid bilayer membranes is a topic of fundamental and biological importance. Whereas questions related to size and composition of fluid membrane domain...

  3. Transport limits in defect-engineered LaAlO3/SrTiO3 bilayers

    NARCIS (Netherlands)

    Gunkel, F.; Wicklein, S.; Hoffmann-Eifert, S.; Meuffels, P.; Brinks, Peter; Huijben, Mark; Waser, R.; Dittmann, R.

    2014-01-01

    The electrical properties of the metallic interface in LaAlO3/SrTiO3 (LAO/STO) bilayers are investigated with focus on the role of cationic defects in thin film STO. Systematic growth-control of the STO thin film cation stoichiometry (defect-engineering) yields a relation between cationic defects in

  4. Computer Simulations of Lipid Bilayers and Proteins

    DEFF Research Database (Denmark)

    Sonne, Jacob

    2006-01-01

    entitled Computer simulations of lipid bilayers and proteins describes two molecular dynamics (MD) simulation studies of pure lipid bilayers as well as a study of a transmembrane protein embedded in a lipid bilayer matrix. Below follows a brief overview of the thesis. Chapter 1. This chapter is a short...... introduction, where I briefly describe the basic biological background for the systems studied in Chapters 3, 4 and 5. This is done in a non-technical way to allow the general interested reader to get an impression of the work. Chapter 2, Methods: In this chapter the background for the methods used......, Pressure profile calculations in lipid bilayers: A lipid bilayer is merely $\\sim$5~nm thick, but the lateral pressure (parallel to the bilayer plane) varies several hundred bar on this short distance (normal to the bilayer). These variations in the lateral pressure are commonly referred to as the pressure...

  5. Fruit and vegetable films and uses thereof

    Science.gov (United States)

    The present invention is directed to monolayer, bilayer, and multilayer films made from fruit, vegetable or a combination thereof, which films have the thinness, strength, flexibility and crispness to serve as alternates or substitutes for seaweed-based films such as nori, while providing nutrition ...

  6. Chemically deposited TiO2/CdS bilayer system for ...

    Indian Academy of Sciences (India)

    Chemical bath deposition (CBD)method was employed to deposit CdS thin film on pre-deposited TiO2 film. A further study has beenmade for structural, surface morphological, optical and photoelectrochemical (PEC) properties of FTO/TiO2, FTO/CdS and FTO/TiO2/CdS bilayers system. PEC behaviour of FTO/TiO2/CdS ...

  7. Bilayer self-assembly on a hydrophilic, deterministically nano-patterned surface

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Gregory Scott [ORNL; Jung, Seung-Yong [ORNL; Browning, Jim [ORNL; Keum, Jong Kahk [ORNL; Lavrik, Nickolay V [ORNL; Alemseghed, Mussie G [ORNL; Collier, Pat [ORNL

    2013-01-01

    We present measurements of the in-situ, microscopic architecture of a self-assembled bilayer at the interface between a regularly nano-patterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nano-scaled holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this study, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion (VF) or by the Langmuir Schaefer (L-S) technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nano-patterned features.

  8. Electronic transport in bilayer graphene

    International Nuclear Information System (INIS)

    Koshino, Mikito

    2009-01-01

    We present theoretical studies on the transport properties and localization effects of bilayer graphene. We calculate the conductivity by using the effective mass model with the self-consistent Born approximation, in the presence and absence of an energy gap opened by the interlayer asymmetry. We find that, in the absence of the gap, the minimum conductivity approaches the universal value by increasing the disorder potential, and the value is robust in the strong disorder regime where mixing with high-energy states is considerable. The gap-opening suppresses the conductivity over a wide energy range, even in the region away from the gap.We also study the localization effects in the vicinity of zero energy in bilayer graphene. We find that the states are all localized in the absence of the gap, while the gap-opening causes a phase transition analogous to the quantum Hall transition, which is accompanied by electron delocalization.

  9. Spin dynamics of bilayer manganites

    Indian Academy of Sciences (India)

    gations to understand the microscopic mechanism of this phenomenon. Together .... La1.2Sr1.8Mn2O7 optic acoustic. Figure 2. Q scans along [1 0 0] at T = 1.6. K for different constant energy transfers through the reciprocal point Q = (1, 0, 1) ... The optic spin-wave energy gap directly gives the intra-bilayer exchange inter-.

  10. Resistance noise in electrically biased bilayer graphene.

    Science.gov (United States)

    Pal, Atindra Nath; Ghosh, Arindam

    2009-03-27

    We demonstrate that the low-frequency resistance fluctuations, or noise, in bilayer graphene are strongly connected to its band structure and display a minimum when the gap between the conduction and valence band is zero. Using double-gated bilayer graphene devices we have tuned the zero gap and charge neutrality points independently, which offers a versatile mechanism to investigate the low-energy band structure, charge localization, and screening properties of bilayer graphene.

  11. Elastic energy of polyhedral bilayer vesicles.

    Science.gov (United States)

    Haselwandter, Christoph A; Phillips, Rob

    2011-06-01

    In recent experiments [M. Dubois, B. Demé, T. Gulik-Krzywicki, J.-C. Dedieu, C. Vautrin, S. Désert, E. Perez, and T. Zemb, Nature (London) 411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T. Gulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc. Natl. Acad. Sci. USA 101, 15082 (2004)] that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron.

  12. High surface stability of magnetite on bi-layer Fe3O4/Fe/MgO(0 0 1) films under 1 MeV Kr+ ion irradiation

    Czech Academy of Sciences Publication Activity Database

    Kim-Ngan, N.-T.H.; Krupska, M.; Balogh, A.G.; Malinský, Petr; Macková, Anna

    2017-01-01

    Roč. 8, č. 4 (2017), č. článku 045005. E-ISSN 2043-6262 R&D Projects: GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : nanoscience * thin film * surface and interface Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics

  13. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti

    2015-02-23

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2) architecture with self-compliance effect is demonstrated. By using two layers of SnO film, a good memory performance is obtained as compared to the individual oxide films. The memory devices show resistance ratio of 103 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no significant degradation is observed for more than 103 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting filaments.

  14. Study on temperature-dependent carrier transport for bilayer graphene

    Science.gov (United States)

    Liu, Yali; Li, Weilong; Qi, Mei; Li, Xiaojun; Zhou, Yixuan; Ren, Zhaoyu

    2015-05-01

    In order to investigate the temperature-dependent carrier transport property of the bilayer graphene, graphene films were synthesized on Cu foils by a home-built chemical vapor deposition (CVD) with C2H2. Samples regularity, transmittance (T) and layer number were analyzed by transmission electron microscope (TEM) images, transmittance spectra and Raman spectra. Van Der Pauw method was used for resistivity measurements and Hall measurements at different temperatures. The results indicated that the sheet resistance (Rs), carrier density (n), and mobility (μ) were 1096.20 Ω/sq, 0.75×1012 cm-2, and 7579.66 cm2 V-1 s-1 at room temperature, respectively. When the temperature increased from 0 °C to 240 °C, carrier density (n) increased from 0.66×1012 cm-2 to 1.55×1012 cm-2, sheet resistance (Rs) decreased from 1215.55 Ω/sq to 560.77 Ω/sq, and mobility (μ) oscillated around a constant value 7773.99 cm2 V-1 s-1. The decrease of the sheet resistance (Rs) indicated that the conductive capability of the bilayer graphene film increased with the temperature. The significant cause of the increase of carrier density (n) was the thermal activation of carriers from defects and unconscious doping states. Because the main influence on the carrier mobility (μ) was the lattice defect scattering and a small amount of impurity scattering, the carrier mobility (μ) was temperature-independent for the bilayer graphene.

  15. Cholesterol Perturbs Lipid Bilayers Nonuniversally

    International Nuclear Information System (INIS)

    Pan Jianjun; Mills, Thalia T.; Tristram-Nagle, Stephanie; Nagle, John F.

    2008-01-01

    Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K C , the thickness D HH , and the orientational order parameter S xray of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K C when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains

  16. DNA nanotechnology: Bringing lipid bilayers into shape

    Science.gov (United States)

    Howorka, Stefan

    2017-07-01

    Lipid bilayers form the thin and floppy membranes that define the boundary of compartments such as cells. Now, a method to control the shape and size of bilayers using DNA nanoscaffolds has been developed. Such designer materials advance synthetic biology and could find use in membrane research.

  17. Alcohol's Effects on Lipid Bilayer Properties

    Science.gov (United States)

    Ingólfsson, Helgi I.; Andersen, Olaf S.

    2011-01-01

    Alcohols are known modulators of lipid bilayer properties. Their biological effects have long been attributed to their bilayer-modifying effects, but alcohols can also alter protein function through direct protein interactions. This raises the question: Do alcohol's biological actions result predominantly from direct protein-alcohol interactions or from general changes in the membrane properties? The efficacy of alcohols of various chain lengths tends to exhibit a so-called cutoff effect (i.e., increasing potency with increased chain length, which that eventually levels off). The cutoff varies depending on the assay, and numerous mechanisms have been proposed such as: limited size of the alcohol-protein interaction site, limited alcohol solubility, and a chain-length-dependent lipid bilayer-alcohol interaction. To address these issues, we determined the bilayer-modifying potency of 27 aliphatic alcohols using a gramicidin-based fluorescence assay. All of the alcohols tested (with chain lengths of 1–16 carbons) alter the bilayer properties, as sensed by a bilayer-spanning channel. The bilayer-modifying potency of the short-chain alcohols scales linearly with their bilayer partitioning; the potency tapers off at higher chain lengths, and eventually changes sign for the longest-chain alcohols, demonstrating an alcohol cutoff effect in a system that has no alcohol-binding pocket. PMID:21843475

  18. The impact of resveratrol in lipid bilayers

    DEFF Research Database (Denmark)

    Shen, Chen; Ghellinck, Alexis de; Fragneto, Giovanna

    knowledge on its probable working mechanism is rare. In this biophysical study, neutron reflectometry was used to investigate the direct impact of resveratrol on lipid membranes with solid supported bilayers. When interacting with di- palmitoyl-phosphatidyl-choline (DPPC) bilayers, resveratrol accumulates...

  19. Room temperature exchange bias in BiFeO3 / Co-Fe bilayers

    OpenAIRE

    Sterwerf, Christian; Meinert, Markus; Arenholz, Elke; Schmalhorst, Jan-Michael; Reiss, Günter

    2015-01-01

    Thin highly epitaxial BiFeO$_3$ films were prepared on SrTiO$_3$ (100) substrates by reactive magnetron co-sputtering. Detailed MOKE measurements on BiFeO$_3$/Co-Fe bilayers were performed to investigate the exchange bias as a function of the films thicknesses and Co-Fe stoichiometries. We found a maximum exchange bias of H$_{\\mathrm{eb}}$=92 Oe and a coercive field of H$_{\\mathrm{c}}$=89 Oe for a 12.5 nm thick BiFeO$_3$ film with a 2 nm thick Co layer. The unidirectional anisotropy is clearl...

  20. Correlating bilayer tablet delamination tendencies to micro-environmental thermodynamic conditions during pan coating.

    Science.gov (United States)

    Zacour, Brian M; Pandey, Preetanshu; Subramanian, Ganeshkumar; Gao, Julia Z; Nikfar, Faranak

    2014-06-01

    The objective of this study was to determine the impact that the micro-environment, as measured by PyroButton data loggers, experienced by tablets during the pan coating unit operation had on the layer adhesion of bilayer tablets in open storage conditions. A full factorial design of experiments (DOE) with three center points was conducted to study the impact of final tablet hardness, film coating spray rate and film coating exhaust temperature on the delamination tendencies of bilayer tablets. PyroButton data loggers were placed (fixed) at various locations in a pan coater and were also allowed to freely move with the tablet bed to measure the micro-environmental temperature and humidity conditions of the tablet bed. The variance in the measured micro-environment via PyroButton data loggers accounted for 75% of the variance in the delamination tendencies of bilayer tablets on storage (R(2 )= 0.75). A survival analysis suggested that tablet hardness and coating spray rate significantly impacted the delamination tendencies of the bilayer tablets under open storage conditions. The coating exhaust temperature did not show good correlation with the tablets' propensity to crack indicating that it was not representative of the coating micro-environment. Models created using data obtained from the PyroButton data loggers outperformed models created using primary DOE factors in the prediction of bilayer tablet strength, especially upon equipment or scale transfers. The coating micro-environment experienced by tablets during the pan coating unit operation significantly impacts the strength of the bilayer interface of tablets on storage.

  1. "Nanocrystal bilayer for tandem catalysis"

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  2. Surface and grain boundary interdiffusion in nanometer-scale LSMO/BFO bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Virendra [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Gaur, Anurag, E-mail: anuragdph@gmail.com [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Choudhary, R.J.; Gupta, Mukul [UGC-DAE Consortium for Scientific Research, Indore 452 001 (India)

    2016-05-01

    Epitaxial 150 nm thick LSMO/BFO bilayer is deposited on STO (100) substrate by pulsed laser deposition, to study magnetoelectric effect. Unexpected low value of room temperature magnetization in bilayer indicates towards the possibility of interdiffusion. Further, sharp fall in the value of T{sub C} (53 K) also added our anxiety towards possible interdiffusion in BFO/LSMO system. Low-angle x-ray diffraction technique is used to investigate interdiffusion phenomena, and the temperature-dependent interdiffusivity is obtained by accurately monitoring the decay of the first-order modulation peak as a function of annealing time. It has been found that the diffusivity at different temperatures follows Arrhenius-type behavior. X-ray reflection (XRR) pattern obtained for the bilayer could not be fitted in the Parratt’s formalism, which confirms the interdiffusion in it. Depth profiles of {sup 209}Bi, {sup 56}Fe ions measured by secondary ion mass spectroscope (SIMS) further substantiate the diffusion of these ions from upper BFO layer into lower LSMO layer. - Highlights: • The LSMO/BFO bilayer is deposited by PLD method. • Structural, magnetic and interfacial properties of deposited films were studied. • In this article, we have raised the problem of interdiffusion in this bilayer, which can hinder its application in devices. Therefore, we feel that our article presents important finding in the area of ceramics research.

  3. Properties of POPC/POPE supported lipid bilayers modified with hydrophobic quantum dots on polyelectrolyte cushions.

    Science.gov (United States)

    Kolasinska-Sojka, Marta; Wlodek, Magdalena; Szuwarzynski, Michal; Kereiche, Sami; Kovacik, Lubomir; Warszynski, Piotr

    2017-10-01

    The formation and properties of supported lipid bilayers (SLB) containing hydrophobic nanoparticles (NP) was studied in relation to underlying cushion obtained from selected polyelectrolyte multilayers. Lipid vesicles were formed from zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in phosphate buffer (PBS). As hydrophobic nanoparticles - quantum dots (QD) with size of 3.8nm (emission wavelength of 420nm) were used. Polyelectrolyte multilayers (PEM) were constructed by the sequential, i.e., layer-by-layer (LbL) adsorption of alternately charged polyelectrolytes from their solutions. Liposomes and Liposome-QDs complexes were studied with Transmission Cryo-Electron Microscopy (Cryo-TEM) to verify the quality of vesicles and the position of QD within lipid bilayer. Deposition of liposomes and liposomes with quantum dots on polyelectrolyte films was studied in situ using quartz crystal microbalance with dissipation (QCM-D) technique. The fluorescence emission spectra were analyzed for both: suspension of liposomes with nanoparticles and for supported lipid bilayers containing QD on PEM. It was demonstrated that quantum dots are located in the hydrophobic part of lipid bilayer. Moreover, we proved that such QD-modified liposomes formed supported lipid bilayers and their final structure depended on the type of underlying cushion. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Possible influence of the ferromagnetic/antiferromagnetic interface on the effective critical behavior of bilayers based on La{sub 1−x}Sr{sub x}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez Miño, Lucero, E-mail: lalvarezm@unal.edu.co [Universidad Nacional de Colombia, Sede Manizales, Cra. 27 #64-60, Manizales (Colombia); Grupo de Superconductividad y Nuevos Materiales, Universidad Nacional de Colombia, Sede Bogotá, Avenida Carrera 30 #45, Bogotá (Colombia); Mulcué-Nieto, Luis Fernando, E-mail: lfmulcuen@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Cra. 27 #64-60, Manizales (Colombia)

    2015-03-01

    In this work, the effective critical exponent of the spontaneous magnetization, β, and the transition temperature, T{sub C}, were calculated from magnetization measurements of three bilayers based on La{sub 1−x}Sr{sub x}MnO{sub 3} (LSMO). The bilayers structure is a ferromagnetic (FM) LSMO film grown on top of an antiferromagnetic (AF) LSMO film. The value of the antiferromagnetic film thickness was kept the same for the three samples, while the ferromagnetic film had different thickness for each bilayer. Applying a method of calculation based on a linear superposition of the magnetization close to the critical temperature, a β value corresponding to the 3D Ising model was found for the bilayer with the thinnest ferromagnetic film. This result, and the other obtained values are explained taking into account the possible influence of the FM/AF interface on the magnetic and crystal orderings. - Highlights: • The critical exponent β of three LSMO bilayers was determined. • Two bilayers with the thinner FM layer have very similar transition temperature. • Two bilayers with the thinner FM layer have very similar width values. • We have found values of β of the 3D Ising model. • Interface also seems to be responsible for some structural disorder.

  5. Direct electrostatic toner marking with poly(3,4-ethylenedioxythiophene)polystyrenesulfonate bilayer devices

    Science.gov (United States)

    Kanungo, Mandakini; Law, Kock-Yee; Zhang, Yuanjia

    2012-10-01

    Poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT:PSS) is the one of the most promising and widely used materials for low cost large area flexible displays, owing to its easy solution processing and micro/nano scale patternability. In this work, hole injection between PEDOT:PSS thin film and molecularly doped polymer layers of arylamine has been studied in a bilayer device configuration. The electrical properties of the bilayer devices have been examined by studying their charge-discharge behavior, current-voltage (I-V), and time-of-flight (TOF) characteristics. The work function of the PEDOT:PSS and arylamine has been estimated by electrochemical measurements. Results show that PEDOT:PSS is an efficient hole injector to arylamine owing to its favorable molecular energetics. The efficiency of hole injection depends on the conductivity of the PEDOT:PSS film and the strength of the electric field across the bilayer device. The interfacial electrical contact behavior between PEDOT and arylamine studied by steady state I-V measurements and TOF measurements suggests that for highly conductive PEDOT:PSS, the discharge of the bilayer device is limited by the hole mobility in the charge transport layer whereas it is injection limited for more resistive PEDOT:PSS films. Printing experiments were performed on a modified xerographic DC12 printer as well as a modified DC8000 development housing. The overall results show that the latent image produced by discharging the bilayer device can be developed electrostatically with toner. More importantly, we found that the PEDOT:PSS bilayer device can be charged, discharged, and developed by just loading it against a negatively biased magnetic toner brush. We suggest coupling this direct toner marking process with an active backplane for digital printing application. The proposed digital printer appears to be very simple and compact as printing can be done without using a charger and the laser ROS system and replacing the

  6. Synthesis and microstructural studies of annealed Cu(2)O/Cu(x)S bilayer as transparent electrode material for photovoltaic and energy storage devices.

    Science.gov (United States)

    Taleatu, B A; Arbab, E A A; Omotoso, E; Mola, G T

    2014-10-01

    Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X-ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu2 O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  7. Development of an automation technique for the establishment of functional lipid bilayer arrays

    Science.gov (United States)

    Hansen, J. S.; Perry, M.; Vogel, J.; Vissing, T.; Hansen, C. R.; Geschke, O.; Emnéus, J.; Nielsen, C. H.

    2009-02-01

    In the present work, a technique for establishing multiple black lipid membranes (BLMs) in arrays of micro structured ethylene tetrafluoroethylene (ETFE) films, and supported by a micro porous material was developed. Rectangular 8 × 8 arrays with apertures having diameters of 301 ± 5 µm were fabricated in ETFE Teflon film by laser ablation using a carbon dioxide laser. Multiple lipid membranes could be formed across the micro structured 8 × 8 array ETFE partitions. Success rates for the establishment of cellulose-supported BLMs across the multiple aperture arrays were above 95%. However, the time course of the membrane thinning process was found to vary considerably between multiple aperture bilayer experiments. An airbrush partition pretreatment technique was developed to increase the reproducibility of the multiple lipid bilayers formation during the time course from the establishment of the lipid membranes to the formation of bilayers. The results showed that multiple lipid bilayers could be reproducible formed across the airbrush-pretreated 8 × 8 rectangular arrays. The ionophoric peptide valinomycin was incorporated into established membrane arrays, resulting in ionic currents that could be effectively blocked by tetraethylammonium. This shows that functional bimolecular lipid membranes were established, and furthermore outlines that the established lipid membrane arrays could host functional membrane-spanning molecules.

  8. Modification of photosensing property of CdS–Bi{sub 2}S{sub 3} bi-layer by thermal annealing and swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shaikh, Shaheed U.; Siddiqui, Farha Y. [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India); Singh, Fouran; Kulriya, Pawan K. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Phase, D.M. [UGC DAE Consortium for Scientific Research, Khandwa Road, Indore 452017 (India); Sharma, Ramphal, E-mail: ramphalsharma@yahoo.com [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India)

    2016-02-01

    The CdS–Bi{sub 2}S{sub 3} bi-layer thin films have been deposited on Indium Tin Oxide (ITO) glass substrates at room temperature by Chemical Bath Deposition Technique (CBD) and bi-layer thin films were annealed in air atmosphere for 1 h at 250 {sup °}C. The air annealed sample was irradiated using Au{sup 9+} ions at the fluence 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. Effects of Swift Heavy Ion (SHI) irradiation on CdS–Bi{sub 2}S{sub 3} bi-layer thin films were studied. The results are explained on the basis annealing and high electronic excitation, using X-ray diffraction (XRD), Selective Electron Area Diffraction (SEAD), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV spectroscopy and I–V characteristics. The photosensing property after illumination of visible light over the samples is studied. These as-deposited, annealed and irradiated bi-layer thin films are used to sense visible light at room temperature. - Graphical abstract: Schematic illustration of CdS–Bi{sub 2}S{sub 3} bi-layer thin film (a) As-deposited (b) Annealed (c) irradiated sample respectively (d) Model of bi-layer photosensor device (e) Graph of illumination intensity verses photosensitivity. - Highlights: • CdS–Bi{sub 2}S{sub 3} bi-layer thin film prepared at room temperature. • Irradiated using Au{sup 9+} ions at the fluence of 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. • Study of modification induced by irradiations. • Study of Photosensitivity after annealing and irradiation.

  9. Tunable excitons in bilayer graphene

    Science.gov (United States)

    Ju, Long; Wang, Lei; Cao, Ting; Taniguchi, Takashi; Watanabe, Kenji; Louie, Steven G.; Rana, Farhan; Park, Jiwoong; Hone, James; Wang, Feng; McEuen, Paul L.

    2017-11-01

    Excitons, the bound states of an electron and a hole in a solid material, play a key role in the optical properties of insulators and semiconductors. Here, we report the observation of excitons in bilayer graphene (BLG) using photocurrent spectroscopy of high-quality BLG encapsulated in hexagonal boron nitride. We observed two prominent excitonic resonances with narrow line widths that are tunable from the mid-infrared to the terahertz range. These excitons obey optical selection rules distinct from those in conventional semiconductors and feature an electron pseudospin winding number of 2. An external magnetic field induces a large splitting of the valley excitons, corresponding to a g-factor of about 20. These findings open up opportunities to explore exciton physics with pseudospin texture in electrically tunable graphene systems​.

  10. Fragmented state of lipid bilayers in water

    DEFF Research Database (Denmark)

    Helfrich, W.; Thimmel, J.; Klösgen, Beate Maria

    1999-01-01

    The bilayers of some typical biological membrane lipids such as PC and DGDG disintegrate in a large excess of water to form an optically invisible dispersive bilayer phase. `Dark bodies' can be reversibly precipitated from it by raising the temperature. The dispersive phase probably consists...... of `knotted sticks', i.e. very thin nodular tubes of bilayer. After reviewing pertinent experimental and theoretical work we report on the discovery of a lower consolute point near room temperature in DGDG/water systems. Its existence shows that the dispersive phase and the dark bodies belong to the same...

  11. Hydrophobic silver nanoparticles trapped in lipid bilayers: Size distribution, bilayer phase behavior, and optical properties

    Directory of Open Access Journals (Sweden)

    Bothun Geoffrey D

    2008-11-01

    Full Text Available Abstract Background Lipid-based dispersion of nanoparticles provides a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on how the presence of nanoparticles influences lipid vesicle stability and bilayer phase behavior. In this work, the formation of aqueous lipid/nanoparticle assemblies (LNAs consisting of hydrophobic silver-decanethiol particles (5.7 ± 1.8 nm embedded within 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC bilayers is demonstrated as a function of the DPPC/Ag nanoparticle (AgNP ratio. The effect of nanoparticle loading on the size distribution, bilayer phase behavior, and bilayer fluidity is determined. Concomitantly, the effect of bilayer incorporation on the optical properties of the AgNPs is also examined. Results The dispersions were stable at 50°C where the bilayers existed in a liquid crystalline state, but phase separated at 25°C where the bilayers were in a gel state, consistent with vesicle aggregation below the lipid melting temperature. Formation of bilayer-embedded nanoparticles was confirmed by differential scanning calorimetry and fluorescence anisotropy, where increasing nanoparticle concentration suppressed the lipid pretransition temperature, reduced the melting temperature, and disrupted gel phase bilayers. The characteristic surface plasmon resonance (SPR wavelength of the embedded nanoparticles was independent of the bilayer phase; however, the SPR absorbance was dependent on vesicle aggregation. Conclusion These results suggest that lipid bilayers can distort to accommodate large hydrophobic nanoparticles, relative to the thickness of the bilayer, and may provide insight into nanoparticle/biomembrane interactions and the design of multifunctional liposomal carriers.

  12. The action of polyene antibiotics on lipid bilayer membranes in the presence of several cations and anions

    NARCIS (Netherlands)

    Zutphen, H. van; Demel, R.A.; Norman, A.W.; Deenen, L.L.M. van

    1971-01-01

    1. 1. Filipin complex, filipin II, filipin III, nystatin, etruscomycin, and pimaricin at concentrations of 10−5 M were able to disrupt bimolecular lipid films containing lecithin and cholesterol in a 1:1 molar ratio. 2. 2. The above antibiotics were not able to disrupt lecithin bilayer

  13. Supramolecular protein immobilization on lipid bilayers

    NARCIS (Netherlands)

    Bosmans, R.P.G.; Hendriksen, W.E.; Verheijden, Mark Lloyd; Eelkema, R.; Jonkheijm, Pascal; van Esch, J.H.; Brunsveld, Luc

    2015-01-01

    Protein immobilization on surfaces, and on lipid bilayers specifically, has great potential in biomolecular and biotechnological research. Of current special interest is the immobilization of proteins using supramolecular noncovalent interactions. This allows for a reversible immobilization and

  14. Interaction of elaiophylin with model bilayer membrane

    Science.gov (United States)

    Genova, J.; Dencheva-Zarkova, M.

    2017-01-01

    Elaiophylin is a new macrodiolide antibiotic, which is produced by the Streptomyces strains [1]. It displays biological activities against Gram-positive bacteria and fungi. The mode of action of this antibiotic has been attributed to an alteration of the membrane permeability. When this antibiotic is inserted into the bilayer membranes destabilization of the membrane and formation of ion-penetrable channels is observed. The macrodiolide antibiotic forms stable cation selective ion channels in synthetic lipid bilayer membranes. The aim of this work was to study the interactions of Elaiophylin with model bilayer membranes and to get information on the mechanical properties of lipid bilayers in presence of this antibiotic. Patch-clamp technique [2] were used in the study

  15. Infrared spectroscopy of fluid lipid bilayers.

    Science.gov (United States)

    Hull, Marshall C; Cambrea, Lee R; Hovis, Jennifer S

    2005-09-15

    Infrared spectroscopy is a powerful technique for examining lipid bilayers; however, it says little about the fluidity of the bilayer-a key physical aspect. It is shown here that it is possible to both acquire spectroscopic data of supported lipid bilayer samples and make measurements of the membrane fluidity. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FT-IR) is used to obtain the spectroscopic information and fluorescence recovery after photobleaching (FRAP) is used to determine the fluidity of the samples. In the infrared spectra of lipid bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, the following major peaks were observed; nu(as)(CH3) 2954 cm(-1), nu(s)(CH3) 2870 cm(-1), nu(as)(CH2) 2924 cm(-1), nu(s)(CH2) 2852 cm(-1), nu(C=O) 1734 cm(-1), delta(CH2) 1463-1473 cm(-1), nu(as)(PO2-) 1226 cm(-1), nu(s)(PO2-) 1084 cm(-1), and nu(as)(N+(CH3)3) 973 cm(-1). The diffusion coefficient of the same lipid bilayer was measured to be 3.5 +/- 0.5 micom(2)/s with visual recovery also noted through use of epifluorescence microscopy. FRAP and visual data confirm the formation of a uniform, mobile supported lipid bilayer. The combination of ATR-FT-IR and FRAP provides complementary data giving a more complete picture of fully hydrated model membrane systems.

  16. Embedding Ba Monolayers and Bilayers in Boron Carbide Nanowires.

    Science.gov (United States)

    Yu, Zhiyang; Luo, Jian; Shi, Baiou; Zhao, Jiong; Harmer, Martin P; Zhu, Jing

    2015-11-26

    Aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was employed to study the distribution of barium atoms on the surfaces and in the interiors of boron carbide based nanowires. Barium based dopants, which were used to control the crystal growth, adsorbed to the surfaces of the boron-rich crystals in the form of nanometer-thick surficial films (a type of surface complexion). During the crystal growth, these dopant-based surface complexions became embedded inside the single crystalline segments of fivefold boron-rich nanowires collectively, where they were converted to more ordered monolayer and bilayer modified complexions. Another form of bilayer complexion stabilized at stacking faults has also been identified. Numerous previous works suggested that dopants/impurities tended to segregate at the stacking faults or twinned boundaries. In contrast, our study revealed the previously-unrecognized possibility of incorporating dopants and impurities inside an otherwise perfect crystal without the association to any twin boundary or stacking fault. Moreover, we revealed the amount of barium dopants incorporated was non-equilibrium and far beyond the bulk solubility, which might lead to unique properties.

  17. π-Donors microstructuring on surface of polymer film by their noncovalent interactions with iodine

    Energy Technology Data Exchange (ETDEWEB)

    Traven, Valerii F., E-mail: valerii.traven@gmail.com [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Ivanov, Ivan V.; Dolotov, Sergei M. [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Veciana, Jaume Miro; Lebedev, Victor S. [Institut de Ciencia de Materials de Barcelona–CSIC, Campus de la UAB, 08193, Bellaterra (Spain); Shulga, Yurii M.; Khasanov, Salavat S. [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Acad. N.N. Semenov Prosp., 1, Chernogolovka, 142432 (Russian Federation); Medvedev, Michael G. [A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119991, Vavilova str., 28 (Russian Federation); Laukhina, Elena E. [The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine, ICMAB-CSIC, Bellaterra, 08193 (Spain)

    2015-06-15

    Noncovalent (charge transfer) interaction between perylene and iodine in polycarbonate film provides formation of microstructured perylene layer on the polymer surface upon exposure of polymer film which contains dissolved perylene to solvent + iodine vapors. The prepared bilayer film possesses a sensing effect to iodine vapors which can be observed by both fluorescence and electrical conductivity changes. Similar bilayer films have been prepared also with anthracene and phenothiazine as π-donors with use of different polymer matrixes. Interaction of iodine with polycyclic aromatic hydrocarbons (PAH) has also been studied by the M06-2x DFT calculations for better understanding of phenomenon of π-donors microstructuring on surface of polymer film. - Highlights: • Preparation of bilayer polymer films with π-donors on surface for the first time. • π-Donor phase purity is confirmed by XRD, IR spectroscopy, SEM. • Perylene bilayer polymer films possess fluorescence. • Perylene bilayer polymer films loss fluorescence under iodine vapors. • Perylene bilayer polymer films possess electrical conductivity when treated by iodine vapors.

  18. Development of molybdenum-gold proximity bilayers as transition edge sensors for the SPEED camera

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.C. E-mail: tchen@stars.gsfc.nasa.gov; Bier, A.; Campano, B.A.; Cottingham, D.A.; Finkbeiner, F.M.; O' Dell, C.; Sharp, E.; Silverberg, R.F.; Wilson, G

    2004-03-11

    Bolometers are being developed with thermistor elements using Mo/Au proximity bilayers as superconducting transition edge sensor. These bolometers will be used by the Spectral Energy Distribution camera which is being developed to study the spectral energy distribution of high redshift galaxies. The bolometers are fabricated on 11x11 mm{sup 2} suspended 0.5 {mu}m thick low-stress LPCVD silicon nitride films supported by 475 {mu}m thick silicon frames. To obtain the required thermal conductivity, the films are perforated to form central disks suspended by thin legs. Here we discuss the design, fabrication process, and current test results of these bolometers.

  19. Thermal behaviour of the Bi profile implanted in bilayer systems

    International Nuclear Information System (INIS)

    Olivieri, C.A.

    1987-01-01

    Implantations of Bi ions into bilayer systems formed by Al films with 1550, 610 e 1000 (angstrom) of thickness evaporated on substrates of Ti,KCL and V respectively are performed. The experiments were made with two main purposes: (1) To compare the implanted ion profiles with the theoretical predictions of the most recent version of the Monte-Carlo simulation program (code TRIM), developed by Biersack and Haggmark, which use the nuclear and electronic stopping powers, based on the universal potential and on the proton stopping power respectively. (2) To study the implanted ion behaviours after isochronal thermal annealings. The depth profiles were analysed via the Rurherford Backscattering Spectroscopy (RBS) technique. The TRIM calculated results are in perfect agreement with the experimental profiles, reproducing very well the discontinuities at the film-substrate interfaces. From the thermal annealing studies, the following conclusions are obtained: (i) The film-substrate interfaces work as diffusion barriers for the implanted ions. (ii) In the KCL sample, thermal annealings at temperatures greater then 300 0 C, showed sequential shifts of the Bi profile in the direction of the surface, which were not observed in the Al/KCL system. (iii) The Al 3 Ti phase precipitation was observed in the Al/Ti system after annealing at 500 0 . (iv). The diffusion coefficient of the implanted ions in the Al/V system was found to be D=5x10 -5 exp(-2.2 eV/KT) cm 2 /s. (author) [pt

  20. RF magnetron sputtering deposition of NiO/Ni bilayer and approach of the Magnetic behavior using the Preisach model

    Energy Technology Data Exchange (ETDEWEB)

    Bendjerad, A., E-mail: bendjerad@gmail.com [L.E.B. Research Laboratory, Electrical Engineering Department, University of Batna 2, Batna (Algeria); Head of Clean Room, L.E.A Laboratory, University of Batna 2, Batna (Algeria); Boukhtache, S. [L.E.B. Research Laboratory, Electrical Engineering Department, University of Batna 2, Batna (Algeria); Benhaya, A. [Head of Clean Room, L.E.A Laboratory, University of Batna 2, Batna (Algeria); Lahmar, A. [Laboratoire de Physiques de la Matière Condensée (LPMC), University of Picardie Jules Vernes, Amiens (France); Zergoug, M. [C.S.C Centre de soudage et de contrôle, Dely Ibrahim, BP 64 Chéraga, Alger (Algeria); Luneau, D. [Université Claude Bernard Lyon 1 Laboratoire des Multimatériaux, (UMR 5615) 69622 cedex (France)

    2017-04-15

    Bilayer of nickel and nickel oxide were deposited on glass substrates using RF magnetron sputtering technique. The magnetic properties of the prepared thin films were carried out at room temperature in both parallel and perpendicular magnetic field to the sample. The Preisach model was applied to provide a mathematical model of the magnetic hysteresis loop in the case of parallel geometry, along the easy axis of the bi-layer NiO / Ni. Good agreement was obtained between the theoretical and experimental results.

  1. TiO{sub 2}/WO{sub 3} photoactive bilayers in the UV-Vis light region

    Energy Technology Data Exchange (ETDEWEB)

    Vasilaki, E. [University of Crete, Department of Chemistry, Heraklion, Crete (Greece); Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Vernardou, D. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Kenanakis, G.; Katsarakis, N. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); Vamvakaki, M. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); University of Crete, Department of Materials Science and Technology, Heraklion, Crete (Greece)

    2017-04-15

    In this work, photoactive bilayered films consisting of anatase TiO{sub 2} and monoclinic WO{sub 3} were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO{sub 3} precursor solution, when deposited as an overlying layer on TiO{sub 2} by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO{sub 2} film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO{sub 2} films with WO{sub 3} acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  2. Energy Storage Characteristics of BiFeO3/BaTiO3 Bi-Layers Integrated on Si

    Directory of Open Access Journals (Sweden)

    Menglin Liu

    2016-11-01

    Full Text Available BiFeO3/BaTiO3 bi-layer thick films (~1 μm were deposited on Pt/Ti/SiO2/(100 Si substrates with LaNiO3 buffer layers at 500 °C via a rf magnetron sputtering process. X-ray diffraction (XRD analysis revealed that both BiFeO3 and BaTiO3 layers have a (00l preferred orientation. The films showed a small remnant polarization (Pr ~ 7.8 μC/cm2 and a large saturated polarization (Ps ~ 65 μC/cm2, resulting in a slim polarization-electric field (P-E hysteresis loop with improved energy storage characteristics (Wc = 71 J/cm3, η = 61%. The successful “slim-down” of the P-E loop from that of the pure BiFeO3 film can be attributed to the competing effects of space charges and the interlayer charge coupling on charge transport of the bi-layer film. The accompanying electrical properties of the bi-layer films were measured and the results confirmed their good quality.

  3. Influence of an Fe cap layer on the structural and magnetic properties of Fe49Pt51/Fe bi-layers

    International Nuclear Information System (INIS)

    Chao-Yang, Duan; Bin, Ma; Zong-Zhi, Zhang; Qing-Yuan, Jin; Fu-Lin, Wei

    2009-01-01

    The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L1 0 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe 49 Pt 51 /Fe bi-layers by their exchange coupling

  4. Possible mechanism of adhesion in a mica supported phospholipid bilayer

    International Nuclear Information System (INIS)

    Pertsin, Alexander; Grunze, Michael

    2014-01-01

    Phospholipid bilayers supported on hydrophilic solids like silica and mica play a substantial role in fundamental studies and technological applications of phospholipid membranes. In both cases the molecular mechanism of adhesion between the bilayer and the support is of primary interest. Since the possibilities of experimental methods in this specific area are rather limited, the methods of computer simulation acquire great importance. In this paper we use the grand canonical Monte Carlo technique and an atomistic force field to simulate the behavior of a mica supported phospholipid bilayer in pure water as a function of the distance between the bilayer and the support. The simulation reveals a possible adhesion mechanism, where the adhesion is due to individual lipid molecules that protrude from the bilayer and form widely spaced links with the support. Simultaneously, the bilayer remains separated from the bilayer by a thin water interlayer which maintains the bilayer fluidity

  5. Ionic motion in PEDOT and PPy conducting polymer bilayers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Careem, M.A.; Skaarup, Steen

    2006-01-01

    Conducting polymer bilayers with poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy), each containing dodecyl benzenesulfonate (DBS) as immobile dopant species, were synthesized galvanostatically. The electrochemical behaviour of the bilayers was investigated using cyclic voltammetry...

  6. Fabrication of Li-intercalated bilayer graphene

    Directory of Open Access Journals (Sweden)

    K. Sugawara

    2011-06-01

    Full Text Available We have succeeded in fabricating Li-intercalated bilayer graphene on silicon carbide. The low-energy electron diffraction from Li-deposited bilayer graphene shows a sharp 3×3R30° pattern in contrast to Li-deposited monolayer graphene. This indicates that Li atoms are intercalated between two adjacent graphene layers and take the same well-ordered superstructure as in bulk C6Li. The angle-resolved photoemission spectroscopy has revealed that Li atoms are fully ionized and the π bands of graphene are systematically folded by the superstructure of intercalated Li atoms, producing a snowflake-like Fermi surface centered at the Γ point. The present result suggests a high potential of Li-intercalated bilayer graphene for application to a nano-scale Li-ion battery.

  7. Light scattering study of irradiated lipid bilayer.

    Science.gov (United States)

    Monem, A S; Blott, B H; Khalil, W A

    1992-05-01

    Vesicular phospholipid bilayer membranes in the form of giant unilamellar vesicles (GUVs) of dipalmitoylphosphatidylcholine (DPPC) were irradiated with fast neutron fluences ranging from 10(4) to 10(7) n cm-2. The phase behaviour of both non-irradiated and irradiated GUVs was investigated using an angular light scattering technique. A model independent size distribution of the samples and their optical anisotropy (delta) were determined using a maximum entropy technique and the theory of light scattering from spherical shells composed of anisotropic cylindrical molecules arranged radially in the shells. The structural changes in the lipid bilayer exposed to fission neutrons are discussed on the basis of the damaging mechanisms of fast neutrons to both the hydrophobic and hydrophilic regions of the lipid bilayer.

  8. In situ atomic force microscope imaging of supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Ipsen, John Hjorth

    2001-01-01

    In situ AFM images of phospholipase A/sub 2/ (PLA/sub 2/) hydrolysis of mica-supported one- and two-component lipid bilayers are presented. For one-component DPPC bilayers an enhanced enzymatic activity is observed towards preexisting defects in the bilayer. Phase separation is observed in two-co...

  9. Crystallization characteristics and recording mechanism of a-Si/Ni bilayer and its potential for use in write-once Blu-ray disc

    Science.gov (United States)

    Her, Yung-Chiun; Jean, Sen-Tsun

    2007-01-01

    The crystallization characteristics and recording mechanism of the a-Si (20nm)/Ni (5 nm) bilayer recording film have been studied. Upon heating, the formation of the metastable NiSi phase occurred at about 200 °C, followed by the formation of the thermodynamically favored NiSi II phase at ~ 400 °C, and the crystallization of a-Si mediated by the Ni silicides below 600 °C, indicating that inserting a thin Ni layer could effectively reduce the crystallization temperature of a-Si. As Si atoms of approximately 92 at% were consumed by NiSi II phase formation, the reflectivity increase of the a-Si/Ni bilayer recording film was contributed to the formation of NiSi II phase. The activation energy for Ni silicide formation was determined to be 1.98 eV. The a-Si/Ni bilayer exhibited an optical contrast of 20% and abosrptance of 54%, which can provide high enough CNR and adequate recording sensitivity. After irradiated by a 405 nm blue laser pulse, a recording mark consisting of NiSi II was clearly formed in the a-Si/Ni bilayer. Under the dynamic test, CNR of 37 dB was achieved at a recording power of 4 mW, demonstrating that the a-Si/Ni bilayer recording film shows a great potential for use in write-once Blu-ray disk.

  10. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique.

    Science.gov (United States)

    Sakuma, Y; Urakami, N; Taniguchi, T; Imai, M

    2011-07-20

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  11. High-performance bilayered electrolyte intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Jin Soo; Camaratta, Matthew A.; Yoon, Heesung; Lee, Byung Wook; Lee, Kang Taek; Jung, Doh Won; Wachsman, Eric D. [Department of Materials Science and Engineering, University for Florida, Gainesville, FL 32611 (United States); Pergolesi, Daniele; Traversa, Enrico [Department of Chemical Science of Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 1, Rome 00133 (Italy); International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2009-07-15

    The ESB/GDC bilayer electrolyte concept has been proved to improve open circuit voltage and reduce the effective area specific resistance of SOFCs utilizing a conventional single-layer GDC electrolyte. However, high performance from such bilayer cells had not yet been demonstrated. The main obstacles toward this end have been fabrication of anode-supported thin-film electrolytes and the reactivity of ESB with conventional cathodes. Recently, an ESB-compatible low area specific resistance cathode was developed: microstructurally optimized Bi{sub 2}Ru{sub 2}O{sub 7}-ESB composites. In addition, we recently developed a novel anode functional layer which can significantly enhance the performance of SOFC utilizing GDC electrolytes. This study combines these recent achievements in SOFC studies and shows that exceptionally high performance of SOFC is possible using ESB/GDC bilayer electrolytes and Bi{sub 2}Ru{sub 2}O{sub 7}-ESB composite cathodes. The result confirms that the bilayer electrolyte and the Bi{sub 2}Ru{sub 2}O{sub 7}-ESB cathode can increase the open circuit potential and reduce the total area specific resistance. The maximum power density of the bilayered SOFC was improved to 1.95 W cm{sup -2} with 0.079 {omega} cm{sup 2} total cell area specific resistance at 650 C. This is the highest power yet achieved in the IT range and we believe redefines the expectation level for maximum power under IT-SOFC operating conditions. (author)

  12. Optimization of a VOC Sensor with a Bilayered Diaphragm Using FBAR as Strain Sensing Elements

    Directory of Open Access Journals (Sweden)

    Huihui Guo

    2017-08-01

    Full Text Available Film bulk acoustic resonators (FBARs are widely applied in mass bio-sensing and pressure sensors, owing to their extreme sensitivity and integration ability, and ability to miniaturize circuits. A volatile organic compound (VOC sensor with a polymer-coated diaphragm, using FBARs as a strain sensing element is proposed and optimized. This vapor sensor is based on organic vapor-induced changes of mechanical deformation of the micro-diaphragm. The four FBARs are located at the edge of the bi-layer diaphragm comprising silicon nitride and silicon oxide for strain extraction. In this work, the strain distribution of the FBAR area under vapor loads is obtained using the finite element analysis (FEA and the response frequency changes of the FBARs under vapor loads are obtained based on both the first-principle methods to deduce the elastic coefficient variation of aluminum nitride film in FBARs under the bending stresses and the Mason equivalent circuit model of the sensor using ADS software. Finally, optimizations are performed on both the bilayered diaphragm structure and sensing film. The diaphragm with a 0.7 μm silicon nitride layer and a 0.5 μm silicon oxide layer are considered to be the optimized design. The optimal coverage area of the sensing film for the diaphragm is around 0.8.

  13. Method to disperse lipids as aggregates in oil for bilayers production.

    Science.gov (United States)

    Claudet, Cyrille; In, Martin; Massiera, Gladys

    2016-01-01

    Several techniques to assemble artificial lipid bilayers involve the zipping of monolayers. Their efficiency is determined by the renewal of the saturated monolayers to be zipped and this proceeds by adsorption of lipids dispersed in oil as aggregates. The size of these lipids aggregates is a key parameter to ensure both the stability of the suspension and a fast release of lipids at the interface. We propose a new method inspired from the solvent-shifting nucleation process allowing to control and tune the lipid aggregates size and that improves the production of artificial membranes. It is simpler and faster than current methods starting from a dry lipid film, which are highly sensitive to environmental conditions. This method opens the route to bilayer production processes with new potentialities in membrane composition.

  14. Catalytic effect of Al and AlN interlayer on the growth and properties of containing carbon films

    International Nuclear Information System (INIS)

    Zhou, Bing; Liu, Zhubo; Tang, Bin; Rogachev, A.V.

    2015-01-01

    Highlights: • DLC and CN x bilayers with Al (AlN) interlayer were fabricated by cathode arc technique. • Complete diffusion of Al and C atoms occurs at the interface of Al/DLC (CN x ) bilayer. • Al/CN x bilayer presents a higher content of Csp 3 /Csp 2 bonds. • The hardness of Al/DLC bilayer decreases but increases for the other bilayers. • Morphology of the bilayers was explained by growth mechanism of DLC and surface state of substrate. - Abstract: Diamond-like carbon (DLC) and carbon nitride (CN x ) bilayer films with Al and AlN interlayer were fabricated by pulse cathode arc technique. The structure, composition, morphology and mechanical properties of the films were investigated by Raman, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Knoop sclerometer and surface profilometer. The results indicated that the complete diffusion between C and Al atoms occurs in the Al/DLC and Al/CN x bilayer. Al interlayer induces the increase of the size and ordering of Csp 2 clusters in the films but AlN interlayer increases the disordering degree of Csp 2 clusters. XPS results showed that a higher content of Csp 3 /Csp 2 bonds presents in the Al/CN x bilayer, and Al and AlN interlayer decreases the atomic ratio of N/C. AFM with phase contrast mode illustrated the morphologic characteristics of the bilayer films. All the bilayers show a nano-structural surface. The morphology changes of the bilayer were well explained by the surface state of the substrate and the growth mechanism of DLC films. The hardness of Al/DLC bilayer decreases but it increases for the other bilayers compared to the corresponding DLC (CN x ) monolayer. The internal stress of the bilayer is significantly lower than that of the monolayer except for the AlN/CN x bilayer. These studies could make the difference at the time of choosing a suitable functional film for certain application

  15. Bi-layer functionally gradient thick film semiconducting methane ...

    Indian Academy of Sciences (India)

    Gas sensors based on metal oxide semiconductors like tin dioxide are widely used for the detection of toxic and combustible gases like carbon monoxide, methane and LPG. One of the problems of such sensors is their lack of sensitivity, which to some extent, can be circumvented by using different catalysts. However, highly ...

  16. Mixed Mechanism of Lubrication by Lipid Bilayer Stacks.

    Science.gov (United States)

    Boţan, Alexandru; Joly, Laurent; Fillot, Nicolas; Loison, Claire

    2015-11-10

    Although the key role of lipid bilayer stacks in biological lubrication is generally accepted, the mechanisms underlying their extreme efficiency remain elusive. In this article, we report molecular dynamics simulations of lipid bilayer stacks undergoing load and shear. When the hydration level is reduced, the velocity accommodation mechanism changes from viscous shear in hydration water to interlayer sliding in the bilayers. This enables stacks of hydrated lipid bilayers to act as efficient boundary lubricants for various hydration conditions, structures, and mechanical loads. We also propose an estimation for the friction coefficient; thanks to the strong hydration forces between lipid bilayers, the high local viscosity is not in contradiction with low friction coefficients.

  17. Electronic properties of graphene-based bilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.com [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); Sboychakov, A.O. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Rakhmanov, A.L. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); All-Russia Research Institute of Automatics, Moscow, 127055 (Russian Federation); Nori, Franco, E-mail: fnori@riken.jp [CEMS, RIKEN, Saitama 351-0198 (Japan); Physics Department, The University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2016-08-23

    This article reviews the theoretical and experimental work related to the electronic properties of bilayer graphene systems. Three types of bilayer stackings are discussed: the AA, AB, and twisted bilayer graphene. This review covers single-electron properties, effects of static electric and magnetic fields, bilayer-based mesoscopic systems, spin–orbit coupling, dc transport and optical response, as well as spontaneous symmetry violation and other interaction effects. The selection of the material aims to introduce the reader to the most commonly studied topics of theoretical and experimental research in bilayer graphene.

  18. Finite element modeling of lipid bilayer membranes

    Science.gov (United States)

    Feng, Feng; Klug, William S.

    2006-12-01

    A numerical simulation framework is presented for the study of biological membranes composed of lipid bilayers based on the finite element method. The classic model for these membranes employs a two-dimensional-fluid-like elastic constitutive law which is sensitive to curvature, and subjects vesicles to physically imposed constraints on surface area and volume. This model is implemented numerically via the use of C1-conforming triangular Loop subdivision finite elements. The validity of the framework is tested by computing equilibrium shapes from previously-determined axisymmetric shape-phase diagram of lipid bilayer vesicles with homogeneous material properties. Some of the benefits and challenges of finite element modeling of lipid bilayer systems are discussed, and it is indicated how this framework is natural for future investigation of biologically realistic bilayer structures involving nonaxisymmetric geometries, binding and adhesive interactions, heterogeneous mechanical properties, cytoskeletal interactions, and complex loading arrangements. These biologically relevant features have important consequences for the shape mechanics of nonidealized vesicles and cells, and their study requires not simply advances in theory, but also advances in numerical simulation techniques, such as those presented here.

  19. Condensation energy of the superconducting bilayer cuprates

    Indian Academy of Sciences (India)

    May & June 2002 physics pp. 861–866. Condensation energy of the superconducting bilayer cuprates. GOVIND1, AJAY2 and S K JOSHI1,3,∗. 1Theory Group, National Physical Laboratory, Dr. K.S. ... 2Department of Physics, G.B. Pant University of Agriculture and Technology, ..... [1] B Batlogg, Physics Today 44, 45 (1991).

  20. Bifurcation of self-folded polygonal bilayers

    Science.gov (United States)

    Abdullah, Arif M.; Braun, Paul V.; Hsia, K. Jimmy

    2017-09-01

    Motivated by the self-assembly of natural systems, researchers have investigated the stimulus-responsive curving of thin-shell structures, which is also known as self-folding. Self-folding strategies not only offer possibilities to realize complicated shapes but also promise actuation at small length scales. Biaxial mismatch strain driven self-folding bilayers demonstrate bifurcation of equilibrium shapes (from quasi-axisymmetric doubly curved to approximately singly curved) during their stimulus-responsive morphing behavior. Being a structurally instable, bifurcation could be used to tune the self-folding behavior, and hence, a detailed understanding of this phenomenon is appealing from both fundamental and practical perspectives. In this work, we investigated the bifurcation behavior of self-folding bilayer polygons. For the mechanistic understanding, we developed finite element models of planar bilayers (consisting of a stimulus-responsive and a passive layer of material) that transform into 3D curved configurations. Our experiments with cross-linked Polydimethylsiloxane samples that change shapes in organic solvents confirmed our model predictions. Finally, we explored a design scheme to generate gripper-like architectures by avoiding the bifurcation of stimulus-responsive bilayers. Our research contributes to the broad field of self-assembly as the findings could motivate functional devices across multiple disciplines such as robotics, artificial muscles, therapeutic cargos, and reconfigurable biomedical devices.

  1. INTERLAYER OPTICAL CONDUCTIVITY OF A SUPERCONDUCTING BILAYER

    NARCIS (Netherlands)

    GARTSTEIN, YN; RICE, MJ; VANDERMAREL, D

    1994-01-01

    We employ the Bardeen-Cooper-Schrieffer theory to calculate the frequency-dependent interlayer conductivity of a superconducting bilayer, the two layers of which are coupled by weak single-particle tunneling. The effect of the superconducting transition on the normal-state absorption band is to

  2. Topological transformation of a surfactant bilayer

    DEFF Research Database (Denmark)

    Le, T.D.; Olsson, U.; Mortensen, K.

    2000-01-01

    Surfactant lamellar phases are often complicated by the formation of multilamellar (onions) under shear, which can originate simply by shaking the sample. A systematic study has been performed on the C10E3-D2O system in which different bilayer structures under a steady shear flow were investigated...

  3. Lipid bilayers decorated with photosensitive ruthenium complexes

    NARCIS (Netherlands)

    Bahreman, Azadeh

    2013-01-01

    In this thesis the thermal- and photo-substitution behavior of polypyridyl ruthenium complexes is described at the surface of lipid bilayers and in homogeneous solutions. It is shown that the successive thermal binding and light-induced unbinding of the cationic ruthenium complex at the surface of

  4. Nonmonotonic critical temperature in superconductor ferromagnet bilayers

    NARCIS (Netherlands)

    Fominov, Ya. V.; Fominov, I.V.; Chtchelkatchev, N.M.; Golubov, Alexandre Avraamovitch

    2002-01-01

    The critical temperature Tc of a superconductor/ferromagnet (SF) bilayer can exhibit nonmonotonic dependence on the thickness df of the F layer. SF systems have been studied for a long time; according to the experimental situation, a ¿dirty¿ limit is often considered which implies that the mean free

  5. Condensation energy of the superconducting bilayer cuprates

    Indian Academy of Sciences (India)

    cuprates also depends on the number of CuO2 layers per unit cell and the extent of doping. In a bilayer or ... unit cell is smaller than the adjacent layers in a single layer system; therefore it is natural to include interlayer .... energy conservation principle, the change in the kinetic energy of the electrons in the out- of-plane ...

  6. Effects of carotenoids on lipid bilayers.

    Science.gov (United States)

    Johnson, Quentin R; Mostofian, Barmak; Fuente Gomez, Gabriel; Smith, Jeremy C; Cheng, Xiaolin

    2018-01-31

    Carotenoids have been found to be important in improving the integrity of biomembranes in eukaryotes. However, the molecular details of how carotenoids modulate the physical properties of biomembranes are unknown. To this end, we have conducted a series of molecular dynamics simulations of different biologically-relevant membranes in the presence of carotenoids. The carotenoid effect on the membrane was found to be specific to the identity of the carotenoid and the composition of the membrane itself. Therefore, different classes of carotenoids produce a different effect on the membrane, and different membrane phases are affected differently by carotenoids. It is apparent from our data that carotenoids do trigger the bilayer to become thinner. The mechanism by which this occurs depends on two competing factors, the ability of the lipid tails of opposing monolayers to either (1) compress or (2) interdigitate as the bilayer condenses. Indeed, carotenoids directly influence the physical properties via these two mechanisms, thus compacting the bilayer. However, the degree to which these competing mechanisms are utilized depends on the bilayer phase and the carotenoid identity.

  7. The impact of resveratrol in lipid bilayers

    DEFF Research Database (Denmark)

    Shen, Chen; Ghellinck, Alexis de; Fragneto, Giovanna

    mechanism is unspecific. However, there are only few biophysical studies regarding the impact of resveratrol on lipid membranes. Here, results from a neutron reflectometry investigation on solid supported di-palmitoyl-phosphatidyl-choline (DPPC) bilayers with incorporated resveratrol are presented. The data...

  8. Localized plasmons in bilayer graphene nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Xiao, Sanshui; Mortensen, N. Asger

    2016-01-01

    We study localized plasmonic excitations in bilayer graphene (BLG) nanodisks, comparing AA-stacked and AB-stacked BLG and contrasting the results to the case of two monolayers without electronic hybridization. The electrodynamic response of the BLG electron gas is described in terms of a spatially...

  9. Microstructures and Recording Mechanism of Mo/Si Bilayer Applied for Write-Once Blue Laser Optical Recording

    Directory of Open Access Journals (Sweden)

    Sin-Liang Ou

    2014-01-01

    Full Text Available Mo/Si bilayer thin films were grown by magnetron sputtering and applied to write-once blu-ray disc (BD-R. The microstructures and optical storage properties of Mo/Si bilayer were investigated. From the temperature dependence of reflectivity measurement, it was revealed that a phase change occurred in the range of 255–425°C. Transmission electron microscopy analysis showed that the as-deposited film possessed Mo polycrystalline phase. The hexagonal MoSi2 and cubic Mo3Si phases appeared after annealing at 300 and 450°C, respectively. By measuring the optical reflectivity at a wavelength of 405 nm, the optical contrast of Mo/Si bilayer between as-deposited and 450°C-annealed states was evaluated to 25.8%. The optimum jitter value of 6.8% was obtained at 10.65 mW for 4× recording speed. The dynamic tests show that the Mo/Si bilayer has high potential in BD-R applications.

  10. Dispersion of fullerenes in phospholipid bilayers and the subsequent phase changes in the host bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jeng, U-S. [National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China)]. E-mail: usjeng@nsrrc.org.tw; Hsu, C.-H. [National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China); Lin, T.-L. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Wu, C.-M. [Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Chen, H.-L. [Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Tai, L.-A. [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Hwang, K.-C. [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2005-02-28

    We have studied the structure and phase transition characteristics of the fullerenes (C{sub 60})-embedded lipid bilayers. With small-angle neutron scattering (SANS), we have observed a degradation of bilayer ordering and a suppression effect on the phase transitions of the host vesicle bilayers of dipalmitoylphosphatidylcholine (DPPC), due to the embedment of fullerenes. The fullerene-embedded lipid system with substrate-oriented bilayers is also investigated using X-ray reflectivity and grazing incident small-angle X-ray scattering (GISAXS). In the depth direction, the multilamellar peaks observed in the X-ray reflectivity profile for the oriented DPPC/C{sub 60} bilayers reveal a larger head-to-head distance D{sub HH} of 50.6 A and a bilayer spacing D of 59.8 A, compared to the D{sub HH}=47.7 A and D=59.5 A for a pure DPPC membrane measured at the same conditions. Furthermore, the lipid head layers and water layers in the extracted electron density profile for the complex system are highly smeared, implying a fluctuating or corrugated structure in this zone. Correspondingly, GISAXS for the oriented DPPC/C{sub 60} membrane reveals stronger diffuse scatterings along the membrane plane than that for the pure DPPC system, indicating a higher in-plane correlation associated with the embedded fullerenes.

  11. Development of Boron-Doped ZnO Films with Novel Thin Zn-Rich Film and Their Application to Solar Cells

    Science.gov (United States)

    Hongsingthong, Aswin; Wada, Hidetoshi; Moriya, Yuki; Sichanugrist, Porponth; Konagai, Makoto

    2012-10-01

    In this paper, we report newly developed high-haze glass/zinc oxide (ZnO) substrates with low resistivity by a combination of unique etched soda-lime glass and bilayered ZnO films with a Zn-rich (oxygen-poor) layer. The high mobility and low resistivity of bilayered ZnO films could be obtained with Zn-rich conditions. By depositing the ZnO films onto textured glass substrates, the obtained films exhibit an excellent light-scattering property, while their electrical property is still good. Furthermore, the bilayered ZnO films with a Zn-rich layer did not negatively affect the transparency of the films. Employing the bilayered ZnO films with a Zn-rich layer and an rms roughness of about 274 nm as the front transparent conductive oxide (TCO) in hydrogenated amorphous silicon (a-Si:H) solar cells, we improved the performance and quantum efficiency (QE) of the fabricated solar cells, particularly in the short-wavelength region without the deterioration of open-circuit voltage or fill factor. Thus, the developed glass/bilayered ZnO film with a Zn-rich layer is a new promising material since its resistivity is low while its light-scattering property is still high.

  12. Droplet shape analysis and permeability studies in droplet lipid bilayers.

    Science.gov (United States)

    Dixit, Sanhita S; Pincus, Alexandra; Guo, Bin; Faris, Gregory W

    2012-05-15

    We apply optical manipulation to prepare lipid bilayers between pairs of water droplets immersed in an oil matrix. These droplet pairs have a well-defined geometry allowing the use of droplet shape analysis to perform quantitative studies of the dynamics during bilayer formation and to determine time-dependent values for the droplet volumes, bilayer radius, bilayer contact angle, and droplet center-line approach velocity. During bilayer formation, the contact angle rises steadily to an equilibrium value determined by the bilayer adhesion energy. When there is a salt concentration imbalance between droplets, there is a measurable change in the droplet volume. We present an analytical expression for this volume change and use this expression to calculate the bilayer permeability to water.

  13. Nanomechanics of pH-Responsive, Drug-Loaded, Bilayered Polymer Grafts.

    Science.gov (United States)

    Nalam, Prathima C; Lee, Hyun-Su; Bhatt, Nupur; Carpick, Robert W; Eckmann, David M; Composto, Russell J

    2017-04-19

    Stimuli-responsive polymer films play an important role in the development of smart antibacterial coatings. In this study, we consider complementary architectures of polyelectrolyte films, including a thin chitosan layer (CH), poly(acrylic acid) (PAA) brushes, and a bilayer structure of CH grafted to PAA brushes (CH/PAA) as possible candidates for targeted drug delivery platforms. Atomic force microscopy (AFM) was employed to study the structure-mechanical property relationship for these mono- and bi-layered polymer grafts at pH 7.4 and 4.0, corresponding to physiological and biofilm formation conditions, respectively. Herein, the surface interactions between polymer grafts and the negatively charged silica colloid attached to an AFM lever are considered as representative interactions between the antibacterial coating and a bacteria/biofilm. The bilayered structure of CH/PAA showed significantly reduced adhesive interactions in comparison to pure CH but slightly higher interactions in comparison to PAA films. Among PAA and CH/PAA films, upon grafting CH over the PAA brushes, the normal stiffness increased by 10-fold at pH 7.4 and 20-fold at pH 4.0. Notably, the study also showed that the addition of an antibiotic drug such as multicationic Tobramycin (TOB) impacts the mechanical properties of the antibacterial coatings. Competition between TOB and water molecules for the PAA chains is shown to determine the structural properties of PAA and CH/PAA films loaded with TOB. At high pH (7.4), the TOB molecules, which remain multicationic, strongly interact with polyanionic PAA, thereby reducing the film's compressibility. On the contrary, at low pH (4.0), the water molecules preferentially interact with TOB in comparison to uncharged PAA chains and, upon TOB release, results in a stronger film collapse together with an increase in adhesive interactions between the probe, the surface, and the elastic modulus of the film. The bacterial proliferation on these platforms when

  14. Films activos para el envasado de alimentos a base de ácido Poliláctico (PLA) y almidón

    OpenAIRE

    Muller, Justine

    2017-01-01

    Biodegradable active films based on poly(lactic) acid (PLA) and starch were developed and characterized as to their functional and structural properties, using the bilayer film strategy, in order to obtain materials that better meet the food packaging requirements. Plasticization of semicrystalline PLA was analysed by using three different biodegradable compounds to enhance the PLA mechanical performance. Likewise, cinnamaldehyde was incorporated to PLA-starch bilayer films and their antimicr...

  15. Plasmon-waveguide resonance spectroscopy studies of lateral segregation in solid-supported proteolipid bilayers.

    Science.gov (United States)

    Salamon, Zdzislaw; Devanathan, Savitha; Tollin, Gordon

    2007-01-01

    Plasmon-waveguide resonance (PWR) spectroscopy is a high-sensitivity optical method for characterizing thin films immobilized onto the outer surface of a glass prism coated with thin films of a metal (e.g., silver) and a dielectric (e.g., silica). Resonance excitation by a polarized continuous wave (CW) laser above the critical angle for total internal reflection generates plasmon and waveguide modes, whose evanescent electromagnetic fields are localized on the outer surface and interact with the immobilized sample (in the present case a proteolipid bilayer). Plots of reflected light intensity vs the incident angle of the exciting light constitute a PWR spectrum, whose properties are determined by the refractive index (n), the thickness (t), and the optical extinction at the exciting wavelength (k) of the sample. Plasmon excitation can occur using light polarized both perpendicular (p) and parallel (s) to the plane of the resonator surface, allowing characterization of the structural properties of uniaxially oriented proteolipid films deposited on the surface. As will be demonstrated in what follows, PWR spectroscopy provides a powerful tool for directly observing in real-time microdomain formation (rafts) in such bilayers owing to lateral segregation of both lipids and proteins. In favorable cases, protein trafficking can also be monitored. Spectral simulation using Maxwell's equations allows these raft domains to be characterized in terms of their mass densities and thicknesses.

  16. Thermally stable antireflective coatings based on nanoporous organosilicate thin films.

    Science.gov (United States)

    Kim, Suhan; Cho, Jinhan; Char, Kookheon

    2007-06-05

    Thermally stable nanoporous organosilicate thin films were realized by the microphase separation of pore-generating polymers mixed with an organosilicate matrix to be antireflective coatings (ARCs), for which a thin film with a refractive index (n) of 1.23 for zero reflection is required. The refractive index of such nanoporous organosilicate films can be tuned from 1.39 down to 1.23 by incorporating nanopores within the films. With a nanoporous single layer with n approximately 1.23, the light transmittance of the glass above 99.8% was achieved in the visible range (lambda approximately 550 nm). To overcome the limitation on the narrow wavelength for high transmittance imposed by a single antireflective nanoporous thin film, bilayer thin films with different refractive indices were prepared by placing a high refractive index layer with a refractive index of 1.45 below the nanoporous thin film. UV-vis transmittance of a glass coated with the bilayer films was compared with nanoporous single-layer films and it is demonstrated that the novel broadband antireflection coatings in a wide range of visible wavelength can be easily obtained by the organosilicate bilayer thin films described in this study. Also, ARCs developed in this study demonstrate excellent AR durability owing to the hydrophobic nature of the organosilicate matrix.

  17. Electrically Controllable Magnetism in Twisted Bilayer Graphene.

    Science.gov (United States)

    Gonzalez-Arraga, Luis A; Lado, J L; Guinea, Francisco; San-Jose, Pablo

    2017-09-08

    Twisted graphene bilayers develop highly localized states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic or a ferromagnetic (FM) polarization of said regions, depending on the electrical bias between layers. Remarkably, FM-polarized AA regions under bias develop spiral magnetic ordering, with a relative 120° misalignment between neighboring regions due to a frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges naturally without the need of spin-orbit coupling, and competes with the more conventional lattice-antiferromagnetic instability, which interestingly develops at smaller bias under weaker interactions than in monolayer graphene, due to Fermi velocity suppression. This rich and electrically controllable magnetism could turn twisted bilayer graphene into an ideal system to study frustrated magnetism in two dimensions.

  18. Lipid Bilayers: Clusters, Domains and Phases

    OpenAIRE

    Ackerman, David G.; Feigenson, Gerald W.

    2015-01-01

    In this chapter we discuss the complex mixing behavior of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behavior in bilayers and the distinction between these phases and other manifestations of nonrandom mixing found in one-phase mixtures, such as clusters, micelles, and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of ...

  19. Electronic properties of Bilayer Fullerene onions

    Science.gov (United States)

    Pincak, R.; Shunaev, V. V.; Smotlacha, J.; Slepchenkov, M. M.; Glukhova, O. E.

    2017-10-01

    The HOMO-LUMO gaps of the bilayer fullerene onions were investigated. For this purpose, the HOMO and LUMO energies were calculated for the isolated fullerenes using the parametrization of the tight binding method with the Harrison-Goodwin modification. Next, the difference of the Fermi levels of the outer and inner shell was calculated by considering the hybridization of the orbitals on the base of the geometric parameters. The results were obtained by the combination of these calculations.

  20. Interaction of neurotransmitters with a phospholipid bilayer

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Werge, Mikkel; Elf-Lind, Maria Northved

    2014-01-01

    (GOL) with a dipalmitoylphosphatidylcholine (DPPC) bilayer. In agreement with previously published experimental data, we found the lowest membrane affinity for the charged molecules and a moderate affinity for zwitterionic and polar molecules. The affinity can be ranked as follows: ACH–GLU ... phospholipids. Even at that position, these solutes were noticeably hydrated and carried ∼30–80% of the bulk water along. The mobility of hydration water...

  1. Integral Membrane Proteins and Bilayer Proteomics

    OpenAIRE

    Whitelegge, Julian P.

    2013-01-01

    Integral membrane proteins reside within the bilayer membranes that surround cells and organelles, playing critical roles in movement of molecules across them and the transduction of energy and signals. While their extreme amphipathicity presents technical challenges, biological mass spectrometry has been applied to all aspects of membrane protein chemistry and biology, including analysis of primary, secondary, tertiary and quaternary structure, as well as the dynamics that accompany function...

  2. Integral membrane proteins and bilayer proteomics.

    Science.gov (United States)

    Whitelegge, Julian P

    2013-03-05

    Integral membrane proteins reside within the bilayer membranes that surround cells and organelles, playing critical roles in movement of molecules across them and the transduction of energy and signals. While their extreme amphipathicity presents technical challenges, biological mass spectrometry has been applied to all aspects of membrane protein chemistry and biology, including analysis of primary, secondary, tertiary, and quaternary structures as well as the dynamics that accompany functional cycles and catalysis.

  3. Growth, structure and magnetic properties of single crystalline Fe/CoO/Ag(001) bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Abrudan, R.M.

    2007-07-16

    The structural and magnetic properties of epitaxially deposited single-crystalline CoO layers and Fe/CoO bilayers on Ag(001) were investigated. CoO films on Ag(001) exhibit (1 x 1) Low Energy Electron Diffraction (LEED) patterns similar to the clean Ag(001) substrate. The vertical interlayer spacing of the CoO films, deduced from a kinematic analysis of LEED I(E) curves, is a {sub perpendicular} {sub to} /2=2.17 Aa, slightly expanded along the film normal. Scanning Tunneling Microscopy (STM) show a big improvement in the surface roughness after annealing the CoO films at 750 K in oxygen atmosphere. Magnetic measurements using the magneto-optical Kerr effect (MOKE) show a characteristic increase of the coercive field when the Fe/CoO bilayer system is cooled down from room temperature to 150 K. The ordering temperature for the antiferromagnetic layer is in the same range as the Neel temperature for bulk CoO (T{sub N}=290 K). X-ray absorption spectroscopy was employed to probe magnetic and electronic properties with elemental selectivity. Absorption spectra taken from bilayers with different amounts of deposited Fe show only a weak indication for the formation of Fe oxide at the Fe/CoO interface (0.3 ML Fe). From the spectral shape it is concluded that an FeO type of oxide is formed. X-ray Magnetic Circular Dichroism (XMCD) measurements exhibit a sizeable induced ferromagnetic signal at the Co L{sub 2,3} absorption edge, corresponding to an interface layer of 1.1 ML in which the magnetic spins couple with the Fe layer. The angular dependence of the X-ray Magnetic Linear Dichroism (XMLD) and X-ray Magnetic Circular Dichroism XMCD at both the Co and Fe L{sub 2,3} edges shows the orientation of the Co and Fe moments in the bilayers with respect to the crystallographic direction. PhotoElectron Emission Microscope (PEEM) is used to image each ferromagnetic and antiferromagnetic layer separately. Magnetic contrast due to the induced magnetic spins at the interface is also

  4. Ultrafast lithium diffusion in bilayer graphene.

    Science.gov (United States)

    Kühne, Matthias; Paolucci, Federico; Popovic, Jelena; Ostrovsky, Pavel M; Maier, Joachim; Smet, Jurgen H

    2017-09-01

    Solids that simultaneously conduct electrons and ions are key elements for the mass transfer and storage required in battery electrodes. Single-phase materials with a high electronic and high ionic conductivity at room temperature are hard to come by, and therefore multiphase systems with separate ion and electron channels have been put forward instead. Here we report on bilayer graphene as a single-phase mixed conductor that demonstrates Li diffusion faster than in graphite and even surpassing the diffusion of sodium chloride in liquid water. To measure Li diffusion, we have developed an on-chip electrochemical cell architecture in which the redox reaction that forces Li intercalation is localized only at a protrusion of the device so that the graphene bilayer remains unperturbed from the electrolyte during operation. We performed time-dependent Hall measurements across spatially displaced Hall probes to monitor the in-plane Li diffusion kinetics within the graphene bilayer and measured a diffusion coefficient as high as 7 × 10 -5  cm 2 s -1 .

  5. Molecular dynamics modelling of EGCG clusters on ceramide bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Jingjie; Cheng, Yuan; Li, Weifeng; Zhang, Yong-Wei [Institute of High Performance Computing, A*STAR, 138632 (Singapore)

    2015-12-31

    A novel method of atomistic modelling and characterization of both pure ceramide and mixed lipid bilayers is being developed, using only the General Amber ForceField. Lipid bilayers modelled as pure ceramides adopt hexagonal packing after equilibration, and the area per lipid and bilayer thickness are consistent with previously reported theoretical results. Mixed lipid bilayers are modelled as a combination of ceramides, cholesterol, and free fatty acids. This model is shown to be stable after equilibration. Green tea extract, also known as epigallocatechin-3-gallate, is introduced as a spherical cluster on the surface of the mixed lipid bilayer. It is demonstrated that the cluster is able to bind to the bilayers as a cluster without diffusing into the surrounding water.

  6. Cholesterol Protects the Oxidized Lipid Bilayer from Water Injury

    DEFF Research Database (Denmark)

    Owen, Michael C; Kulig, Waldemar; Rog, Tomasz

    2018-01-01

    In an effort to delineate how cholesterol protects membrane structure under oxidative stress conditions, we monitored the changes to the structure of lipid bilayers comprising 30 mol% cholesterol and an increasing concentration of Class B oxidized 1-palmitoyl-2-oleoylphosphatidylcholine (POPC...... in a characteristic reduction in bilayer thickness and increase in area per lipid, thereby increasing the exposure of the membrane hydrophobic region to water. However, cholesterol was observed to help reduce water injury by moving into the bilayer core and forming more hydrogen bonds with the oxPLs. Cholesterol also...... resists altering its tilt angle, helping to maintain membrane integrity. Water that enters the 1-nm-thick core region remains part of the bulk water on either side of the bilayer, with relatively few water molecules able to traverse through the bilayer. In cholesterol-rich membranes, the bilayer does...

  7. Method of fabricating lipid bilayer membranes on solid supports

    Science.gov (United States)

    Cho, Nam-Joon (Inventor); Frank, Curtis W. (Inventor); Glenn, Jeffrey S. (Inventor); Cheong, Kwang Ho (Inventor)

    2012-01-01

    The present invention provides a method of producing a planar lipid bilayer on a solid support. With this method, a solution of lipid vesicles is first deposited on the solid support. Next, the lipid vesicles are destabilized by adding an amphipathic peptide solution to the lipid vesicle solution. This destabilization leads to production of a planar lipid bilayer on the solid support. The present invention also provides a supported planar lipid bilayer, where the planar lipid bilayer is made of naturally occurring lipids and the solid support is made of unmodified gold or titanium oxide. Preferably, the supported planar lipid bilayer is continuous. The planar lipid bilayer may be made of any naturally occurring lipid or mixture of lipids, including, but not limited to phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinsitol, cardiolipin, cholesterol, and sphingomyelin.

  8. Topological Valley Transport at Bilayer Graphene Domain Walls

    Science.gov (United States)

    2015-04-22

    resistances are lower than that expected from the semiconductor bandgap in ideal bilayer graphene , presumably owing to impurities and defects in our devices...LETTER doi:10.1038/nature14364 Topological valley transport at bilayer graphene domain walls Long Ju1*, Zhiwen Shi1*, Nityan Nair1, Yinchuan Lv1...Electron valley, a degree of freedom that is analogous to spin, can lead to novel topological phases in bilayer graphene . A tunable bandgap can be

  9. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    International Nuclear Information System (INIS)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J.

    1994-01-01

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer

  10. The optimization of a Mo bilayer and its application in Cu(In, Ga)Se2 solar cells

    Science.gov (United States)

    Huang, P. C.; Sung, C. C.; Chen, J. H.; Huang, C. H.; Hsu, C. Y.

    2017-12-01

    Molybdenum (Mo) back contact films for Cu(In, Ga)Se2 (CIGS) solar cells are deposited on soda-lime glass (SLG) substrates by direct current (DC) magnetron sputtering with a Mo target in a pure Ar atmosphere. The effect of the DC power (in the range, 100-500 W) and the sputtering pressure (in the range, 0.2-1.8 Pa) on the morphology, the electrical resistivity, the optical reflectance and the adhesive properties of Mo films is determined. The optimum properties for the Mo bilayer are obtained. The quality of the SLG/Mo bilayers/CIGS samples that are selenized at 560 °C is confirmed to be dense and relatively smooth, with very good adherence. No cracking or peeling off is observed after selenization. The X-ray diffraction patterns for the CIGS absorbers film have a chalcopyrite crystal structure with a preferred orientation of (112), (204)/(220) and (312)/(116). The chemical composition of the Cu-In-Ga precursor films and CIGS absorbers are determined using X-ray fluorescence spectroscopy. The secondary ion mass spectroscopy surface chemical analysis for the CIGS films shows that the Ga element moves away from the surface and accumulates at the bottom of the sample and Se diffuses into the Mo surface, which indicates the possible completion of selenization. The CIGS solar cells that are produced have a maximum photo-conversion efficiency of 12.83%.

  11. Polar orientation of a pendant anionic chromophore in thick layer-by-layer self-assembled polymeric films

    OpenAIRE

    Garg, Akhilesh; Davis, Richey M.; Durak, Cemil; Heflin, James R.; Gibson, Harry W.

    2008-01-01

    Multilayer films with up to 600 bilayers and 740 nm thickness were fabricated using the alternating deposition of poly(allylamine hydrochloride) and poly{1-[p-(3'-carboxy-4'-hydroxyphenylazo)benzenesulfonamido]-1,2-ethand iyl} on glass substrates. Linear relationships for absorbance, thickness, and the square root of the second harmonic intensity versus the number of bilayers demonstrates that the films have long range polar order and optical homogeneity. The deposition conditions (i.e., pH o...

  12. Properties of silicon nanocrystals with boron and phosphorus doping fabricated via silicon rich oxide and silicon dioxide bilayers

    Science.gov (United States)

    Chien-Jen Yang, Terry; Nomoto, Keita; Puthen-Veettil, Binesh; Lin, Ziyun; Wu, Lingfeng; Zhang, Tian; Jia, Xuguang; Conibeer, Gavin; Perez-Wurfl, Ivan

    2017-07-01

    Effects of boron and phosphorus doping on the structural, electrical, and optical properties of silicon nanocrystals in superlattice thin films were investigated. Silicon nanocrystals were fabricated via magnetron sputtering of stoichiometric silicon rich oxide and silicon dioxide bilayers followed by high temperature annealing at 1100 degrees Celsius. The characterization techniques used include: high-resolution transmission electron microscopy with energy filtering, grazing incidence x-ray diffraction, Raman, photoluminescence, and photothermal deflection spectroscopy, as well as electrical measurements. Results showed that phosphorus doping causes the loss of the bilayer structure and an increase in the average size of the silicon nanocrystals due to softening of the silicon dioxide matrix during post-sputter annealing. The result was a decrease in quantum confinement and a redshift in photoluminescence spectrum with an absorption profile similar to crystalline silicon. The undoped (intrinsic) sample maintained its bilayer structure and displayed stronger quantum confinement with higher photoluminescence peak energy and higher absorption coefficient. In-between, the boron doped sample was more similar structurally to the intrinsic sample, although merging between bilayers resulted in an extensive silicon nanocrystalline network. Optically, it displayed different effects due to photoluminescence quenching and free carrier absorption. Finally, both doped samples exhibited a decrease in electrical resistivity.

  13. Self-spreading method for forming lipid bilayer on a patterned agarose gel: Toward precise lipid bilayer patterning.

    Science.gov (United States)

    Shimba, Kenta; Shoji, Kazuma; Miyamoto, Yoshitaka; Yagi, Tohru

    2017-07-01

    Forming artificial cell membranes is a suitable strategy for studying drug responses of membrane proteins. In order to form lipid bilayer with both mechanical stability and membrane protein functions, hydrogel supported bilayer has attracted attentions. Combinational use of self-extraction method for lipid bilayer formation and agarose gel patterning should realize hydrogel-supported bilayer with any shape and large area. In this study, we aimed to form a lipid bilayer on a patterned agarose gel and to characterize the membrane. First, lipid mixture was attached on an agarose gel, and lipid layers spread on the gel surface. With fluorescent observation, it is suggested that thin lipid layer was formed on the agarose gel, and their distance-dependent changes in spreading velocity was consistent with that in lipid bilayer. Next, the lipid layer was characterized with fluorescence recovery after photo breaching experiment. As a result, it is indicated that lipid molecules in the lipid layer on the agarose showed lateral diffusion, a typical characteristic of lipid bilayer. Taken together, we confirmed that lipid bilayer can be formed on the patterned agarose gel with self-spreading method. The hydrogel-supported bilayer will be a suitable tool for drug discovery.

  14. Bilayer-thickness-mediated interactions between integral membrane proteins.

    Science.gov (United States)

    Kahraman, Osman; Koch, Peter D; Klug, William S; Haselwandter, Christoph A

    2016-04-01

    Hydrophobic thickness mismatch between integral membrane proteins and the surrounding lipid bilayer can produce lipid bilayer thickness deformations. Experiment and theory have shown that protein-induced lipid bilayer thickness deformations can yield energetically favorable bilayer-mediated interactions between integral membrane proteins, and large-scale organization of integral membrane proteins into protein clusters in cell membranes. Within the continuum elasticity theory of membranes, the energy cost of protein-induced bilayer thickness deformations can be captured by considering compression and expansion of the bilayer hydrophobic core, membrane tension, and bilayer bending, resulting in biharmonic equilibrium equations describing the shape of lipid bilayers for a given set of bilayer-protein boundary conditions. Here we develop a combined analytic and numerical methodology for the solution of the equilibrium elastic equations associated with protein-induced lipid bilayer deformations. Our methodology allows accurate prediction of thickness-mediated protein interactions for arbitrary protein symmetries at arbitrary protein separations and relative orientations. We provide exact analytic solutions for cylindrical integral membrane proteins with constant and varying hydrophobic thickness, and develop perturbative analytic solutions for noncylindrical protein shapes. We complement these analytic solutions, and assess their accuracy, by developing both finite element and finite difference numerical solution schemes. We provide error estimates of our numerical solution schemes and systematically assess their convergence properties. Taken together, the work presented here puts into place an analytic and numerical framework which allows calculation of bilayer-mediated elastic interactions between integral membrane proteins for the complicated protein shapes suggested by structural biology and at the small protein separations most relevant for the crowded membrane

  15. Enhanced Performance of Dye-Sensitized Solar Cells with Graphene/ZnO Nanoparticles Bilayer Structure

    Directory of Open Access Journals (Sweden)

    Chih-Hung Hsu

    2014-01-01

    Full Text Available This study reports characteristics of dye-sensitized solar cells (DSSCs with graphene/ZnO nanoparticle bilayer structure. The enhancement of the performance of DSSCs achieved using graphene/ZnO nanoparticle films is attributable to the introduction of an electron-extraction layer and absorption of light in the visible range and especially in the range 300–420 nm. DSSC that was fabricated with graphene/ZnO nanoparticle film composite photoanodes exhibited a Voc of 0.5 V, a Jsc of 17.5 mA/cm2, an FF of 0.456, and a calculated η of 3.98%.

  16. Magnetic interactions in exchange-coupled yet unbiased IrMn/NiCu bilayers.

    Science.gov (United States)

    Cichelero, R; Harres, A; Sossmeier, K D; Schmidt, J E; Geshev, J

    2013-10-23

    This paper reports experimental and model magnetization results obtained on exchange-coupled ferromagnet/antiferromagnet (FM/AF) bilayers that show zero net bias. The coercivity of the films, either irradiated with He or implanted with Ge ions at 40 keV, varies significantly with the fluence used. We employed the remanence plots technique in order to estimate the nature of the interactions present and check if there exists a correlation between their type and the coercivity variations. The analysis of the remanence plots through numerical simulations based on the Landau-Lifshitz-Gilbert equation demonstrated that outcomes of interactions within the FM layer could be distinguished from those coming from coupling at the FM/AF interface and that demagnetizing interaction effects could be achieved without the presence of dipolar interactions. Our findings indicate that such experiments could give selective information on modifications caused by a post-deposition treatment in each layer of the film.

  17. Unidirectional Spin-Wave-Propagation-Induced Seebeck Voltage in a PEDOT:PSS/YIG Bilayer

    Science.gov (United States)

    Wang, P.; Zhou, L. F.; Jiang, S. W.; Luan, Z. Z.; Shu, D. J.; Ding, H. F.; Wu, D.

    2018-01-01

    We clarify the physical origin of the dc voltage generation in a bilayer of a conducting polymer film and a micrometer-thick magnetic insulator Y3Fe5O12 (YIG) film under ferromagnetic resonance and/or spin wave excitation conditions. The previous attributed mechanism, the inverse spin Hall effect in the polymer [Nat. Mater. 12, 622 (2013), 10.1038/nmat3634], is excluded by two control experiments. We find an in-plane temperature gradient in YIG which has the same angular dependence with the generated voltage. Both vanish when the YIG thickness is reduced to a few nanometers. Thus, we argue that the dc voltage is governed by the Seebeck effect in the polymer, where the temperature gradient is created by the nonreciprocal magnetostatic surface spin wave propagation in YIG.

  18. Lipid bilayers: clusters, domains and phases.

    Science.gov (United States)

    Ackerman, David G; Feigenson, Gerald W

    2015-01-01

    In the present chapter we discuss the complex mixing behaviour of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behaviour in bilayers and the distinction between these phases and other manifestations of non-random mixing found in one-phase mixtures, such as clusters, micelles and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of increasingly complex model membrane systems, with a focus on phase coexistence, morphology and their implications for the cell plasma membrane.

  19. Reversible Polarization Rotation in Epitaxial Ferroelectric Bilayers

    DEFF Research Database (Denmark)

    Liu, Guangqing; Zhang, Qi; Huang, Hsin-Hui

    2016-01-01

    large-scale polarization rotation switching (≈60 μC cm−2) and an effective d 33 response 500% (≈250 pm V−1) larger than the PZT-R layer alone. Furthermore, this enhancement is stable for more than 107 electrical switching cycles. These bilayers present a simple and highly controllable means to design...... and optimize rotational polar systems as an alternate to traditional composition-based approaches. The precise control of the subtle interface-driven interactions between the lattice and the external factors that control polarization opens a new door to enhanced—or completely new—functional properties....

  20. Electric field-triggered metal-insulator transition resistive switching of bilayered multiphasic VOx

    Science.gov (United States)

    Won, Seokjae; Lee, Sang Yeon; Hwang, Jungyeon; Park, Jucheol; Seo, Hyungtak

    2018-01-01

    Electric field-triggered Mott transition of VO2 for next-generation memory devices with sharp and fast resistance-switching response is considered to be ideal but the formation of single-phase VO2 by common deposition techniques is very challenging. Here, VOx films with a VO2-dominant phase for a Mott transition-based metal-insulator transition (MIT) switching device were successfully fabricated by the combined process of RF magnetron sputtering of V metal and subsequent O2 annealing to form. By performing various material characterizations, including scanning transmission electron microscopy-electron energy loss spectroscopy, the film is determined to have a bilayer structure consisting of a VO2-rich bottom layer acting as the Mott transition switching layer and a V2O5/V2O3 mixed top layer acting as a control layer that suppresses any stray leakage current and improves cyclic performance. This bilayer structure enables excellent electric field-triggered Mott transition-based resistive switching of Pt-VOx-Pt metal-insulator-metal devices with a set/reset current ratio reaching 200, set/reset voltage of less than 2.5 V, and very stable DC cyclic switching upto 120 cycles with a great set/reset current and voltage distribution less than 5% of standard deviation at room temperature, which are specifications applicable for neuromorphic or memory device applications. [Figure not available: see fulltext.

  1. Conservation of quantum efficiency in quantum well intermixing by stress engineering with dielectric bilayers

    Science.gov (United States)

    Arslan, Seval; Demir, Abdullah; Şahin, Seval; Aydınlı, Atilla

    2018-02-01

    In semiconductor lasers, quantum well intermixing (QWI) with high selectivity using dielectrics often results in lower quantum efficiency. In this paper, we report on an investigation regarding the effect of thermally induced dielectric stress on the quantum efficiency of quantum well structures in impurity-free vacancy disordering (IFVD) process using photoluminescence and device characterization in conjunction with microscopy. SiO2 and Si x O2/SrF2 (versus SrF2) films were employed for the enhancement and suppression of QWI, respectively. Large intermixing selectivity of 75 nm (125 meV), consistent with the theoretical modeling results, with negligible effect on the suppression region characteristics, was obtained. Si x O2 layer compensates for the large thermal expansion coefficient mismatch of SrF2 with the semiconductor and mitigates the detrimental effects of SrF2 without sacrificing its QWI benefits. The bilayer dielectric approach dramatically improved the dielectric–semiconductor interface quality. Fabricated high power semiconductor lasers demonstrated high quantum efficiency in the lasing region using the bilayer dielectric film during the intermixing process. Our results reveal that stress engineering in IFVD is essential and the thermal stress can be controlled by engineering the dielectric strain opening new perspectives for QWI of photonic devices.

  2. Intermonolayer friction and surface shear viscosity of lipid bilayer membranes

    NARCIS (Netherlands)

    den Otter, Wouter K.; Shkulipa, S.

    2007-01-01

    The flow behavior of lipid bilayer membranes is characterized by a surface viscosity for in-plane shear deformations, and an intermonolayer friction coefficient for slip between the two leaflets of the bilayer. Both properties have been studied for a variety of coarse-grained double-tailed model

  3. Magnetically assisted bilayer composites for soft bending actuators

    NARCIS (Netherlands)

    Jang, S.H.; Na, Seon Hong; Park, Yong Lae

    2017-01-01

    This article presents a soft pneumatic bending actuator using a magnetically assisted bilayer composite composed of silicone polymer and ferromagnetic particles. Bilayer composites were fabricated by mixing ferromagnetic particles to a prepolymer state of silicone in a mold and asymmetrically

  4. In situ atomic force microscope imaging of supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Ipsen, John Hjorth

    2001-01-01

    -component DMPC-DSPC bilayers and a remarkable enhanced hydrolytic activity of the PLA/sub 2/-enzyme for the DMPC-rich phase is seen. Furthermore, in a supported double bilayer system a characteristic ripple structure, most likely related to the formation of the P/sub beta /-ripple phase is observed....

  5. Molecular packing and area compressibility of lipid bilayers

    International Nuclear Information System (INIS)

    White, S.H.; King, G.I.

    1985-01-01

    Knowledge of the molecular packing of lipids and water in lipid bilayers is important for understanding bilayer mechanics and thermodynamics. Information on packing is most often obtained from x-ray or neutron diffraction measurements. Given the d spacing, composition, and partial specific volumes of the lipid and water, it is a simple matter to calculate the area per lipid molecule, bilayer thickness, and bilayer mass density. The partial specific volumes are commonly assumed to be those of bulk water and of lipid in excess water regardless of the degree of bilayer hydration. The authors present evidence here that these assumptions should be seriously questioned. At low hydrations, they find the head groups of egg and dioleoyl lecithin to be much less tightly packed than previously thought and the partial specific volume of water to be considerably smaller than 1 ml/g. Because the molecular packing affects the mechanical properties of bilayers, they use the results to reevaluate published experiments concerning the elastic area compressibility modulus of egg lecithin bilayers and the repulsive hydration force between bilayers

  6. Self-assembling bilayers of palladiumthiolates in organic media

    Indian Academy of Sciences (India)

    Unknown

    length. There is evidence to suggest that the alkyl chains are orientationally disordered especially prior to melting. Keywords. Self-assembling bilayers; palladiumthiolates; lamellar structures. 1. Introduction. Lipid bilayers have long been recognized as being central to molecular organization. Synthetic analogues mimicking ...

  7. Supported lipid bilayers as templates to design manganese oxide ...

    Indian Academy of Sciences (India)

    functions.1 Template directed assemblies of organic– inorganic structures include model bilayer membranes, vesicles and liposomes that have been used extensively to direct organization of the 2D structures.2–12 Among these soft templates, supported lipid bilayers (SLBs) have been gaining importance in recent times.

  8. Interdiffusion and grain-boundary migration in Au-Cu bilayers during ion-irradiation

    International Nuclear Information System (INIS)

    Alexander, D.E.; Rehn, L.E.; Baldo, P.M.

    1991-11-01

    Ion irradiation and annealing experiments have been conducted on Au/Cu bilayer films to evaluate the effect of irradiation on diffusion-induced grain boundary migration (DIGM). The Au films were prepared with a large-grained microstructure with grain boundaries perpendicular to the film surface and extending through the film thickness. Irradiations were conducted with 1.5 MeV Kr at 228 degree C. Rutherford backscattering spectrometry of the samples revealed that interdiffusion was substantially enhanced in the irradiated area relative to the unirradiated area. Both irradiated and annealed-only areas were characterized by a nearly uniform composition of 14 at.% and 7 at.% Cu respectively through the entire thickness of the underlying Au film. Small probe X-ray energy dispersive spectroscopy showed significant lateral compositional homogeneities in both irradiated and annealed areas. These two results are consistent with previous observations of DIGM in the Au/Cu system, suggesting that this previously unexamined mechanism contributes to ion beam mixing

  9. Peierls instability and optical properties of bilayer polyacene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Longlong, E-mail: zhanglonglong@tyut.edu.cn [The College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Xie, Shijie [School of Physics, Shandong University, Jinan 250100 (China)

    2017-05-03

    Highlights: • The Peierls instability of bilayer polyacene is discussed. • The external electric field effect on bilayer polyacene is discussed. • The pressure effect on bilayer polyacene is discussed. • The optical properties of bilayer polyacene are discussed. - Abstract: We reveal that bilayer polyacene can be the gapped state due to the intralayer Peierls instability. There are six topologically inequivalent Peierls-distorted structures and they are degenerate in energy. The external electric field can tune the Peierls gap and induce the semiconductor-to-metallic phase transitions. The optical conductivity spectra are calculated in an attempt to categorize the Peierls-distorted structures. The strength of the interlayer coupling essentially affects the electronic properties and the optical selection rules.

  10. Formation of supported lipid bilayers by vesicle fusion

    DEFF Research Database (Denmark)

    Lind, Tania Kjellerup; Cardenas Gomez, Marite; Wacklin, Hanna

    2014-01-01

    phase-transition temperature of the lipid. We have carefully studied the formation mechanism of supported DPPC bilayers below and above the lipid melting temperature (Tm) by quartz crystal microbalance and atomic force microscopy under continuous flow conditions. We also measured the structure of lipid......We have investigated the effect of deposition temperature on supported lipid bilayer formation via vesicle fusion. By using several complementary surface-sensitive techniques, we demonstrate that despite contradicting literature on the subject, high-quality bilayers can be formed below the main...... bilayers formed below or above Tmby neutron reflection and investigated the effect of subsequent cooling to below the Tm. Our results clearly show that a continuous supported bilayer can be formed with high surface coverage below the lipid Tm. We also demonstrate that the high dissipation responses...

  11. Modeling constrained sintering of bi-layered tubular structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kothanda Ramachandran, Dhavanesan; Ni, De Wei

    2015-01-01

    Constrained sintering of tubular bi-layered structures is being used in the development of various technologies. Densification mismatch between the layers making the tubular bi-layer can generate stresses, which may create processing defects. An analytical model is presented to describe...... the densification and stress developments during sintering of tubular bi-layered samples. The correspondence between linear elastic and linear viscous theories is used as a basis for derivation of the model. The developed model is first verified by finite element simulation for sintering of tubular bi-layer system....... Furthermore, the model is validated using densification results from sintering of bi-layered tubular ceramic oxygen membrane based on porous MgO and Ce0.9Gd0.1O1.95-d layers. Model input parameters, such as the shrinkage kinetics and viscous parameters are obtained experimentally using optical dilatometry...

  12. Thermotropic and Barotropic Phase Behavior of Phosphatidylcholine Bilayers

    Directory of Open Access Journals (Sweden)

    Nobutake Tamai

    2013-01-01

    Full Text Available Bilayers formed by phospholipids are frequently used as model biological membranes in various life science studies. A characteristic feature of phospholipid bilayers is to undergo a structural change called a phase transition in response to environmental changes of their surroundings. In this review, we focus our attention on phase transitions of some major phospholipids contained in biological membranes, phosphatidylcholines (PCs, depending on temperature and pressure. Bilayers of dipalmitoylphosphatidylcholine (DPPC, which is the most representative lipid in model membrane studies, will first be explained. Then, the bilayer phase behavior of various kinds of PCs with different molecular structures is revealed from the temperature–pressure phase diagrams, and the difference in phase stability among these PC bilayers is discussed in connection with the molecular structure of the PC molecules. Furthermore, the solvent effect on the phase behavior is also described briefly.

  13. Spontaneous bending of pre-stretched bilayers.

    Science.gov (United States)

    DeSimone, Antonio

    2018-01-01

    We discuss spontaneously bent configurations of pre-stretched bilayer sheets that can be obtained by tuning the pre-stretches in the two layers. The two-dimensional nonlinear plate model we use for this purpose is an adaptation of the one recently obtained for thin sheets of nematic elastomers, by means of a rigorous dimensional reduction argument based on the theory of Gamma-convergence (Agostiniani and DeSimone in Meccanica. doi:10.1007/s11012-017-0630-4, 2017, Math Mech Solids. doi:10.1177/1081286517699991, arXiv:1509.07003, 2017). We argue that pre-stretched bilayer sheets provide us with an interesting model system to study shape programming and morphing of surfaces in other, more complex systems, where spontaneous deformations are induced by swelling due to the absorption of a liquid, phase transformations, thermal or electro-magnetic stimuli. These include bio-mimetic structures inspired by biological systems from both the plant and the animal kingdoms.

  14. Engineering Lipid Bilayer Membranes for Protein Studies

    Science.gov (United States)

    Khan, Muhammad Shuja; Dosoky, Noura Sayed; Williams, John Dalton

    2013-01-01

    Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques. PMID:24185908

  15. Evaluation of a non-woven fabric coated with a chitosan bi-layer composite for wound dressing.

    Science.gov (United States)

    Liu, Bai-Shuan; Yao, Chun-Hsu; Fang, Shr-Shin

    2008-05-13

    This study presents a novel design of an easily stripped bi-layer composite that consists of an upper layer of a soybean protein non-woven fabric coated with a lower layer, a genipin-crosslinked chitosan film, as a wound dressing material. This study examines the in vitro properties of the genipin-crosslinked chitosan film and the bi-layer composite. Furthermore, in vivo experiments are conducted to study wounds treated with the composite in a rat model. Experimental results show that the degree of crosslinking and the in vitro degradation rate of the genipin-crosslinked chitosan films can be controlled by varying the genipin contents. In addition, the genipin contents should exceed 0.025 wt.-% of the chitosan-based material if complete crosslinking reactions between genipin and chitosan molecules are required. Water contact angle analysis shows that the genipin-crosslinked chitosan film is not highly hydrophilic; therefore, the genipin-crosslinked chitosan layer is not entangled with the soybean protein non-woven fabric, which forms an easily stripped interface layer between them. Furthermore, this new wound dressing material provides adequate moisture, thereby minimizing the risk of wound dehydration, and exhibits good mechanical properties. The in vivo histological assessment results reveal that epithelialization and reconstruction of the wound are achieved by covering the wound with the composite, and the composite is easily stripped from the wound surface without damaging newly regenerated tissue.

  16. Crystallization mechanisms and recording characteristics of Si/CuSi bilayer for write-once blu-ray disc

    Energy Technology Data Exchange (ETDEWEB)

    Ou, Sin-Liang; Kuo, Po-Cheng; Tsai, Tsung-Lin [Departmant of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Sheng-Chi [Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, Taipei 243, Taiwan (China); Yeh, Chin-Yen; Chang, Han-Feng [CMC Magnetics Corporation, Taoyuan 333, Taiwan (China); Lee, Chao-Te; Chiang, Donyau [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 300, Taiwan (China)

    2011-09-19

    The crystallization mechanisms of Si/CuSi bilayer and its recording characteristics for write-once blu-ray disc (BD-R) were investigated. It was found that Cu{sub 3}Si phase appeared during the room temperature sputtered deposition. Then, the Si atoms in CuSi layer segregated and crystallized to cubic Si in Cu{sub 3}Si nucleation sites as the film was annealed at 270 deg. C. After heating to 500 deg. C, the grains size of cubic Si phase grew and the hexagonal Si phase was observed. The dynamic tests show that the Si/CuSi bilayer has great feasibility for 1-4x BD-R with the bottom jitter values below 6.5%.

  17. Upper critical field and vortices in S/F bilayers exhibiting the quasi-onedimensional FFLO-like state

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Daniel; Hemmida, Mamoun; Kehrle, Jan; Zdravkov, Vladimir I.; Ullrich, Aladin; Obermeier, Guenther; Mueller, Claus; Loidl, Alois; Krug von Nidda, Hans-Albrecht; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Sidorenko, Anatolie S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Tagirov, Lenar [Institut fuer Physik, Universitaet Augsburg (Germany); Solid State Physics Department, Kazan Federal University (Russian Federation)

    2015-07-01

    We investigate the temperature dependence of the upper critical field, B{sub c2}, in superconductor/ferromagnet (S/F) bilayers as a function of the F-layer thickness, d{sub F}, by resistance measurements. We extracted GL coherence lengths and estimated an effective thickness of the superconducting layer by evaluating the perpendicular coherence length at the 3D-2D crossover temperature in the parallel B{sub c2}. We found an unexpected non-monotonous behavior of the effective thickness as a function of d{sub F}. Moreover, we investigated the anisotropy of B{sub c2} by microwave absorption. The results show a deviation from Tinkham's prediction for thin films, which we attribute to the additional anisotropy induced by the quasi-1D FFLO-like state. Thus, we propose a new type of vortex, developing in the S/F bilayer in magnetic fields applied close to parallel.

  18. Complementary resistive switching in BaTiO{sub 3}/NiO bilayer with opposite switching polarities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Institut d’Electronique de Micro-électronique et de Nanotechnologie (IEMN), CNRS, Université des Sciences et Technologies de Lille, avenue Poincaré, BP 60069, 59652, Villeneuve d’Ascq cedex (France); Wei, Xianhua, E-mail: weixianhua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Lei, Yao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yuan, Xincai [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zeng, Huizhong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China)

    2016-12-15

    Graphical abstract: Au/BaTiO{sub 3}/NiO/Pt bilayer device shows complementary resistive switching (CRS) without electroforming which is mainly ascribed to anti-serial stack of two RRAM cells with bipolar behaviors. - Highlights: • Complementary resistive switching (CRS) has been investigated in Au/BaTiO{sub 3}/NiO/Pt by stacking the two elements with different switching types. • The realization of complementary resistive switching (CRS) is mainly ascribed to the anti-serial stack of two RRAM cells with bipolar behaviors. • Complementary resistive switching (CRS) in bilayer is effective to solve the sneak current problem briefly and economically. - Abstract: Resistive switching behaviors have been investigated in the Au/BaTiO{sub 3}/NiO/Pt structure by stacking the two elements with different switching types. The conducting atomic force microscope measurements on BaTiO{sub 3} thin films and NiO thin films suggest that with the same active resistive switching region, the switching polarities in the two semiconductors are opposite to each other. It is in agreement with the bipolar hysteresis I–V curves with opposite switching polarities for single-layer devices. The bilayer devices show complementary resistive switching (CRS) without electroforming and unipolar resistive switching (URS) after electroforming. The coexistence of CRS and URS is mainly ascribed to the co-effect of electric field and Joule heating mechanisms, indicating that changeable of resistance in this device is dominated by the redistribution of oxygen vacancies in BaTiO{sub 3} and the formation, disruption, restoration of conducting filaments in NiO. CRS in bilayer with opposite switching polarities is effective to solve the sneak current without the introduction of any selector elements or an additional metal electrode.

  19. Surface modification using peptide functionalized bilayers

    Science.gov (United States)

    Stroumpoulis, Dimitrios

    Engineering materials that are capable of supporting cell and tissue growth is a challenging task that involves identifying and incorporating biological signals into the material surfaces or scaffolds. One approach towards bioactivity in materials is to mimic the function of the extracellular matrix (ECM) by displaying adhesion promoting oligopeptides. Supported planar bilayers (SPB) are a good platform to study molecular interactions at interfaces, since transmembrane proteins and peptides can be incorporated in a biologically relevant environment with precise control over their concentration and presentation. SPBs can be formed on flat surfaces using the Langmuir-Blodgett (LB) technique or alternatively from vesicle solutions. The fusion of vesicles with solid substrates offers simplicity and enhanced bilayer deposition rates over the LB method, whereas it can also be used with convex and enclosed surfaces. Ellipsometry and a mass transport model were used to investigate the kinetics of SPB formation on silicon dioxide surfaces from 100 nm diameter 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles. For the range of concentrations studied, 0.025 to 0.380 mg/ml, a monotonic increase in the ellipsometric signal with time was observed until saturation and the adsorption rate constant was calculated. Further, a Monte Carlo model was used to simulate the SPB formation process and the computational results were successfully fit to the experimental data. Lipid vesicles displaying RGD peptide amphiphiles were fused onto glass coverslips to control the ability of these surfaces to support cell adhesion and growth. Cell adhesion was prevented on phosphatidylcholine bilayers in the absence of RGD, whereas cells adhered and spread in the presence of accessible RGD amphiphiles. This specific interaction between cells and RGD peptides was further explored in a concentration dependent fashion by creating a surface composition array using a microfluidic device. For the

  20. Cluster Formation of Polyphilic Molecules Solvated in a DPPC Bilayer

    Directory of Open Access Journals (Sweden)

    Xiang-Yang Guo

    2017-10-01

    Full Text Available We analyse the initial stages of cluster formation of polyphilic additive molecules which are solvated in a dipalmitoylphosphatidylcholine (DPPC lipid bilayer. Our polyphilic molecules comprise an aromatic (trans-bilayer core domain with (out-of-bilayer glycerol terminations, complemented with a fluorophilic and an alkyl side chain, both of which are confined within the aliphatic segment of the bilayer. Large-scale molecular dynamics simulations (1 μ s total duration of a set of six of such polyphilic additives reveal the initial steps towards supramolecular aggregation induced by the specific philicity properties of the molecules. For our intermediate system size of six polyphiles, the transient but recurrent formation of a trimer is observed on a characteristic timescale of about 100 ns. The alkane/perfluoroalkane side chains show a very distinct conformational distribution inside the bilayer thanks to their different philicity, despite their identical anchoring in the trans-bilayer segment of the polyphile. The diffusive mobility of the polyphilic additives is about the same as that of the surrounding lipids, although it crosses both bilayer leaflets and tends to self-associate.

  1. Reliable Piezoelectricity in Bilayer WSe2 for Piezoelectric Nanogenerators.

    Science.gov (United States)

    Lee, Ju-Hyuck; Park, Jae Young; Cho, Eun Bi; Kim, Tae Yun; Han, Sang A; Kim, Tae-Ho; Liu, Yanan; Kim, Sung Kyun; Roh, Chang Jae; Yoon, Hong-Joon; Ryu, Hanjun; Seung, Wanchul; Lee, Jong Seok; Lee, Jaichan; Kim, Sang-Woo

    2017-08-01

    Recently, piezoelectricity has been observed in 2D atomically thin materials, such as hexagonal-boron nitride, graphene, and transition metal dichalcogenides (TMDs). Specifically, exfoliated monolayer MoS 2 exhibits a high piezoelectricity that is comparable to that of traditional piezoelectric materials. However, monolayer TMD materials are not regarded as suitable for actual piezoelectric devices due to their insufficient mechanical durability for sustained operation while Bernal-stacked bilayer TMD materials lose noncentrosymmetry and consequently piezoelectricity. Here, it is shown that WSe 2 bilayers fabricated via turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a mechanically exfoliated WSe 2 bilayer with Bernal stacking. Turbostratic stacking refers to the transfer of each chemical vapor deposition (CVD)-grown WSe 2 monolayer to allow for an increase in degrees of freedom in the bilayer symmetry, leading to noncentrosymmetry in the bilayers. In contrast, CVD-grown WSe 2 bilayers exhibit very weak piezoelectricity because of the energetics and crystallographic orientation. The flexible piezoelectric WSe 2 bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources, in contrast to monolayer WSe 2 for which the device performance becomes degraded above a strain of 0.63%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Potassium-doped n-type bilayer graphene

    Science.gov (United States)

    Yamada, Takatoshi; Okigawa, Yuki; Hasegawa, Masataka

    2018-01-01

    Potassium-doped n-type bilayer graphene was obtained. Chemical vapor deposited bilayer and single layer graphene on copper (Cu) foils were used. After etching of Cu foils, graphene was dipped in potassium hydroxide aqueous solutions to dope potassium. Graphene on silicon oxide was characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. Both XPS and EDX spectra indicated potassium incorporation into the bilayer graphene via intercalation between the graphene sheets. The downward shift of the 2D peak position of bilayer graphene after the potassium hydroxide (KOH) treatment was confirmed in Raman spectra, indicating that the KOH-treated bilayer graphene was doped with electrons. Electrical properties were measured using Hall bar structures. The Dirac points of bilayer graphene were shifted from positive to negative by the KOH treatment, indicating that the KOH-treated bilayer graphene was n-type conduction. For single layer graphene after the KOH treatment, although electron doping was confirmed from Raman spectra, the peak of potassium in the X-ray photoelectron spectroscopy (XPS) spectrum was not detected. The Dirac points of single layer graphene with and without the KOH treatment showed positive.

  3. The radiation effects on lipid bilayers

    International Nuclear Information System (INIS)

    Ikigai, Hajime; Matsuura, Tomio; Narita, Noboru; Ozawa, Atsushi.

    1980-01-01

    The Radiation effects on lipid bilayers are studied by the electron spin resonance. Egg lecithin liposomes and human erythrocytes are labeled with spin probes (5 SAL, 12 SAL). Effects of membrane fluidity by X-Ray (or ultraviolet) irradiation are measured by change of the order parameter S. The results obtained are as follows: 1) A similar tendency is observed on the order parameter S between X-Ray irradiated egg lecithin liposomes and human erythrocytes. 2) The rapid changes of the membrane fluidity are observed below 1 krad. The fluctuation of membrane fluidity decreases above 1 krad, consequently the membrane has a tendency changing to a rigid state at low dose area. 3) It is suggested that the more effective radicals are hydroxyl radicals and superoxide radicals. 4) The effects of ultraviolet irradiation with hydrogen peroxide show that hydroxyl radicals lead to changes of membrane fluidity. (author)

  4. Valley Topological Phases in Bilayer Sonic Crystals

    Science.gov (United States)

    Lu, Jiuyang; Qiu, Chunyin; Deng, Weiyin; Huang, Xueqin; Li, Feng; Zhang, Fan; Chen, Shuqi; Liu, Zhengyou

    2018-03-01

    Recently, the topological physics in artificial crystals for classical waves has become an emerging research area. In this Letter, we propose a unique bilayer design of sonic crystals that are constructed by two layers of coupled hexagonal array of triangular scatterers. Assisted by the additional layer degree of freedom, a rich topological phase diagram is achieved by simply rotating scatterers in both layers. Under a unified theoretical framework, two kinds of valley-projected topological acoustic insulators are distinguished analytically, i.e., the layer-mixed and layer-polarized topological valley Hall phases, respectively. The theory is evidently confirmed by our numerical and experimental observations of the nontrivial edge states that propagate along the interfaces separating different topological phases. Various applications such as sound communications in integrated devices can be anticipated by the intriguing acoustic edge states enriched by the layer information.

  5. Semiconducting behavior of substitutionally doped bilayer graphene

    Science.gov (United States)

    Mousavi, Hamze; Khodadadi, Jabbar; Grabowski, Marek

    2018-02-01

    In the framework of the Green's functions approach, random tight-binding model and using the coherent potential approximation, electronic characteristics of the bilayer graphene are investigated by exploring various forms of substitutional doping of a single or both layers of the system by either boron and (or) nitrogen atoms. The results for displacement of the Fermi level resemble the behavior of acceptor or donor doping in a conventional semiconductor, dependent on the impurity type and concentration. The particular pattern of doping of just one layer with one impurity type is most efficient for opening a gap within the energy bands which could be tuned directly by impurity concentration. Doping both layers at the same time, each with one impurity type, leads to an anomaly whereby the gap decreases with increasing impurity concentration.

  6. Interfacial Widths of Conjugated Polymer Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    NCSU; UC Berkeley; UCSB; Advanced Light Source; Garcia, Andres; Yan, Hongping; Sohn, Karen E.; Hexemer, Alexander; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Kramer, Edward J.; Ade, Harald

    2009-08-13

    The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.

  7. Chiral Response of Twisted Bilayer Graphene

    Science.gov (United States)

    Stauber, T.; Low, T.; Gómez-Santos, G.

    2018-01-01

    We present an effective (minimal) theory for chiral two-dimensional materials. These materials possess an electromagnetic coupling without exhibiting a topological gap. As an example, we study the response of doped twisted bilayers, unveiling unusual phenomena in the zero frequency limit. An in-plane magnetic field induces a huge paramagnetic response at the neutrality point and, upon doping, also gives rise to a substantial longitudinal Hall response. The system also accommodates nontrivial longitudinal plasmonic modes that are associated with a longitudinal magnetic moment, thus endowing them with a chiral character. Finally, we note that the optical activity can be considerably enhanced upon doping and our general approach would enable systematic exploration of 2D material heterostructures with optical activity.

  8. Lipids, lipid bilayers and vesicles as seen by neutrons

    International Nuclear Information System (INIS)

    Seto, Hideki

    2011-01-01

    Lipid molecules self-assemble into bilayers in water with their hydrocarbon chains facing inward due to their amphiphilic nature. The structural and dynamical properties of lipids and lipid bilayers have been studied by neutron scattering intensively. In this article, 3 topics are shown as typical examples. 1) a time-resolved small-angle neutron scattering on uni-lamellar vesicles composed of deuterated and protonated lipids to determine lipid kinetics, 2) small-angle neutron scattering to investigate spontaneous formation of nanopores on uni-lamellar vesicles, and 3) neutron spin echo study to determine bending modulus of lipid bilayers. (author)

  9. Fluid lipid bilayers: Intermonolayer coupling and its thermodynamic manifestations

    DEFF Research Database (Denmark)

    Hansen, Per Lyngs; Miao, Ling; Ipsen, John Hjorth

    1998-01-01

    possesses "in-plane" degrees of freedom that characterize its physical or chemical state. Thermally excitable deformations of a Lipid bilayer in its geometrical conformation further impart to it ''out-of-plane'' degrees of freedom. In this paper we discuss the issue of intermonolayer coupling in terms......A fluid membrane of lipid bilayer consists of two individual molecular monolayers physically opposed to each other. This unique molecular architecture naturally necessitates the need to treat a lipid-bilayer membrane as one entity of two coupled two-dimensional systems (monolayers), each of which...

  10. Spin Hall magnetoresistance in antiferromagnet/normal metal bilayers

    KAUST Repository

    Manchon, Aurelien

    2017-01-01

    We investigate the emergence of spin Hall magnetoresistance in a magnetic bilayer composed of a normal metal adjacent to an antiferromagnet. Based on a recently derived drift diffusion equation, we show that the resistance of the bilayer depends on the relative angle between the direction transverse to the current flow and the Néel order parameter. While this effect presents striking similarities with the spin Hall magnetoresistance recently reported in ferromagnetic bilayers, its physical origin is attributed to the anisotropic spin relaxation of itinerant spins in the antiferromagnet.

  11. Electrostatic double-layer interaction between stacked charged bilayers

    Science.gov (United States)

    Hishida, Mafumi; Nomura, Yoko; Akiyama, Ryo; Yamamura, Yasuhisa; Saito, Kazuya

    2017-10-01

    The inapplicability of the DLVO theory to multilayered anionic bilayers is found in terms of the co-ion-valence dependence of the lamellar repeat distance. Most of the added salt is expelled from the interlamellar space to the bulk due to the Gibbs-Donnan effect on multiple bilayers with the bulk. The electrostatic double-layer interaction is well expressed by the formula recently proposed by Trefalt. The osmotic pressure due to the expelled ions, rather than the van der Waals interaction, is the main origin of the attractive force between the bilayers.

  12. Memory effects in annealed hybrid gold nanoparticles/block copolymer bilayers

    Science.gov (United States)

    Torrisi, Vanna; Ruffino, Francesco; Licciardello, Antonino; Grazia Grimaldi, Maria; Marletta, Giovanni

    2011-12-01

    We report on the use of the self-organization process of sputtered gold nanoparticles on a self-assembled block copolymer film deposited by horizontal precipitation Langmuir-Blodgett (HP-LB) method. The morphology and the phase-separation of a film of poly- n-butylacrylate- block-polyacrylic acid (P nBuA- b-PAA) were studied at the nanometric scale by using atomic force microscopy (AFM) and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The templating capability of the P nBuA- b-PAA phase-separated film was studied by sputtering gold nanoparticles (NPs), forming a film of nanometric thickness. The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid P nBuA- b-PAA/Au NPs bilayer at T > T g. The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition. The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

  13. Memory effects in annealed hybrid gold nanoparticles/block copolymer bilayers

    Directory of Open Access Journals (Sweden)

    Ruffino Francesco

    2011-01-01

    Full Text Available Abstract We report on the use of the self-organization process of sputtered gold nanoparticles on a self-assembled block copolymer film deposited by horizontal precipitation Langmuir-Blodgett (HP-LB method. The morphology and the phase-separation of a film of poly-n-butylacrylate-block-polyacrylic acid (PnBuA-b-PAA were studied at the nanometric scale by using atomic force microscopy (AFM and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS. The templating capability of the PnBuA-b-PAA phase-separated film was studied by sputtering gold nanoparticles (NPs, forming a film of nanometric thickness. The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg. The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition. The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

  14. Soft magnetization of a semi-hard/soft magnetic bilayer produced by oblique-incidence evaporation

    International Nuclear Information System (INIS)

    Nozawa, Tadao; Morimoto, Fumio; Harazono, Rikio; Nouchi, Norimoto

    2006-01-01

    The possibility of achieving soft magnetization in semi-hard magnetic films such as Fe, Fe 93.5 Si 6.5 , Fe 5 Co 5 and Fe 7 Co 3 is investigated by depositing films on an Fe 2 Ni 8 underlayer by oblique-incidence evaporation. The magnetic anisotropy of the underlayer is strengthened to a depth of several lattice parameters by vapor deposition of the film at an oblique angle to the substrate surface. This method also allows magnetic anisotropy to be induced in strongly isotropic semi-hard magnetic overlayers to a thickness of a few thousands Angstroms. The coercive force of bilayer films measured along the hard-axis is reduced remarkably by this process, and the strength of the anisotropy field is demonstrated to be readily controllable. When magnetic anisotropy exists in both magnetic layers, a significant change is observed in the magnetization processes of the semi-hard magnetic layer and the coercive forces in the hard magnetization direction is dramatically reduced. Soft magnetization of the semi-hard magnetic layer cannot be achieved when magnetic anisotropy exists in only one of the magnetic layers

  15. Programming Feature Size in the Thermal Wrinkling of Metal Polymer Bilayer by Modulating Substrate Viscoelasticity.

    Science.gov (United States)

    Das, Anuja; Banerji, Aditya; Mukherjee, Rabibrata

    2017-07-12

    We report a novel strategy for creating stress-induced self-organized wrinkles in a metal polymer bilayer with programmable periodicity (λ S ) varying over a wide range, from ∼20 μm down to ∼800 nm by modulating the viscoelasticity of the bottom polymer layer. Substrates with different viscoelasticity are prepared by precuring thin films of a thermo-curable poly dimethylsiloxane (PDMS) elastomer (Sylgard 184) for different durations (t P ) prior to deposition of the top aluminum layer by thermal evaporation. Precuring of the Sylgard 184 film for different durations leads to films with different degrees of viscoelasticity due to variation in the extent of cross-linking of the polymer matrix. The λ S as well as the amplitude (a S ) of the wrinkles progressively decrease with an increase in the extent of elasticity of the film, manifested as an increase in the storage modulus (G'). Based on the variation in the rate of decay of λ S with G', we identify three clearly distinguishable regimes over predominantly viscous, viscoelastic, and elastic bottom layers. While λ S and a S drop with an increase in G' for both the first and the third regimes, it remains nearly independent of G' for the intermediate regime. This is attributed to the difference in the mechanisms of wrinkle formation in the different regimes. We finally show that simultaneous modulation of λ S and a S can be used to engineer surfaces with different wettability as well as anti-reflection properties.

  16. Nanometric hybrid films of xanthan and magnetite

    International Nuclear Information System (INIS)

    Pereira, Edla M.A.; Silva, Anielle M.; Petri, Denise F.S.

    2011-01-01

    Magnetite nanoparticles (NMM) were synthesized by co-characterized by means of X-ray diffraction, infrared spectroscopy and potentiometric titration. Xanthan thin films and NMM were deposited alternately onto Si wafers. The attachment of first xanthan layer onto Si wafer was obtained in the presence of Ca 2+ 1 mM and at pH 10. Under these conditions calcium ions interact electrostatically with both silanol groups and xanthan carboxylate groups, yielding stable xanthan (1.5 ± 0.5) nm thick films. The deposition of NMM was forced by applying a magnetic field set under the sample. The following bilayers were formed by 'layer-by-layer' electrostatic process and magnetic field action. The bilayers formation was monitored by the variation in the ellipsometric angles values, Δ e ψ, and atomic force microscopy. (author)

  17. The role of polymer films on the oxidation of magnetite nanoparticles

    Science.gov (United States)

    Letti, C. J.; Paterno, L. G.; Pereira-da-Silva, M. A.; Morais, P. C.; Soler, M. A. G.

    2017-02-01

    A detailed investigation about the role of polymer films on the oxidation process of magnetite nanoparticles (∼7 nm diameter), under laser irradiation is performed employing micro Raman spectroscopy. To support this investigation, Fe3O4-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe3O4-np/PSS)n with n=2,3,5,7,10 and 25 bilayers are employed as a model system to study the oxidation process under laser irradiation. Raman data are further processed by principal component analysis. Our findings suggest that PSS protects Fe3O4-np from oxidation when compared to powder samples, even for the sample with the greater number of bilayers. Further, the oxidation of magnetite to maghemite occurs preferably for thinner films up to 7 bilayers, while the onset for the formation of the hematite phase depends on the laser intensity for thicker films. Water takes part on the oxidation processes of magnetite, the oxidation/phase transformation of Fe3O4-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe3O4-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite.

  18. Fluorination of Isotopically Labeled Turbostratic and Bernal Stacked Bilayer Graphene

    Czech Academy of Sciences Publication Activity Database

    Ek Weis, Johan; da Costa, Sara; Frank, Otakar; Bastl, Zdeněk; Kalbáč, Martin

    2015-01-01

    Roč. 21, č. 3 (2015), s. 1081-1087 ISSN 1521-3765 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : fluorination * graphene * bilayers Subject RIV: CF - Physical ; Theoretical Chemistry

  19. Pairing of cholesterol with oxidized phospholipid species in lipid bilayers

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Loubet, Bastien; Olzynska, Agnieszka

    2014-01-01

    We claim that (1) cholesterol protects bilayers from disruption caused by lipid oxidation by sequestering conical shaped oxidized lipid species such as 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PZPC) away from phospholipid, because cholesterol and the oxidized lipid have complementary...... shapes and (2) mixtures of cholesterol and oxidized lipids can self-assemble into bilayers much like lysolipid–cholesterol mixtures. The evidence for bilayer protection comes from molecular dynamics (MD) simulations and dynamic light scattering (DLS) measurements. Unimodal size distributions of extruded...... vesicles (LUVETs) made up of a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and PZPC containing high amounts of PZPC are only obtained when cholesterol is present in high concentrations. In simulations, bilayers containing high amounts of PZPC become porous, unless cholesterol is also present...

  20. Observation of Anomalous Resistance Behavior in Bilayer Graphene.

    Science.gov (United States)

    Liu, Yanping; Lew, Wen Siang; Liu, Zongwen

    2017-12-01

    Our measurement results have shown that bilayer graphene exhibits an unexpected sharp transition of the resistance value in the temperature region 200~250 K. We argue that this behavior originates from the interlayer ripple scattering effect between the top and bottom ripple graphene layer. The inter-scattering can mimic the Coulomb scattering but is strongly dependent on temperature. The observed behavior is consistent with the theoretical prediction that charged impurities are the dominant scatters in bilayer graphene. The resistance increase with increasing perpendicular magnetic field strongly supports the postulate that magnetic field induces an excitonic gap in bilayer graphene. Our results reveal that the relative change of resistance induced by magnetic field in the bilayer graphene shows an anomalous thermally activated property.

  1. Biophysical changes induced by xenon on phospholipid bilayers.

    Science.gov (United States)

    Booker, Ryan D; Sum, Amadeu K

    2013-05-01

    Structural and dynamic changes in cell membrane properties induced by xenon, a volatile anesthetic molecule, may affect the function of membrane-mediated proteins, providing a hypothesis for the mechanism of general anesthetic action. Here, we use molecular dynamics simulation and differential scanning calorimetry to examine the biophysical and thermodynamic effects of xenon on model lipid membranes. Our results indicate that xenon atoms preferentially localize in the hydrophobic core of the lipid bilayer, inducing substantial increases in the area per lipid and bilayer thickness. Xenon depresses the membrane gel-liquid crystalline phase transition temperature, increasing membrane fluidity and lipid head group spacing, while inducing net local ordering effects in a small region of the lipid carbon tails and modulating the bilayer lateral pressure profile. Our results are consistent with a role for nonspecific, lipid bilayer-mediated mechanisms in producing xenon's general anesthetic action. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Pair interaction of bilayer-coated nanoscopic particles

    International Nuclear Information System (INIS)

    Qi-Yi, Zhang

    2009-01-01

    The pair interaction between bilayer membrane-coated nanosized particles has been explored by using the self-consistent field (SCF) theory. The bilayer membranes are composed of amphiphilic polymers. For different system parameters, the pair-interaction free energies are obtained. Particular emphasis is placed on the analysis of a sequence of structural transformations of bilayers on spherical particles, which occur during their approaching processes. For different head fractions of amphiphiles, the asymmetrical morphologies between bilayers on two particles and the inverted micellar intermediates have been found in the membrane fusion pathway. These results can benefit the fabrication of vesicles as encapsulation vectors for drug and gene delivery. (condensed matter: structure, thermal and mechanical properties)

  3. Bi-Layer Wound Dressing System for Combat Casualty Care

    National Research Council Canada - National Science Library

    Martineau, Lucie; Shek, Pang N

    2004-01-01

    .... Considering that commercially available dressings are not designed to meet the challenges of treating combat burn wounds, DRDC-Toronto has designed a novel, absorbent and medicated bi-layer wound...

  4. Bi-Layer Wound Dressing System for Combat Casualty Care

    National Research Council Canada - National Science Library

    Martineau, Lucie; Shek, Pang N

    2004-01-01

    .... Considering that commercially available dressings are not designed to meet the challenges of treating combat burn wounds, DRDC Toronto has designed a novel, absorbent and medicated bi-layer wound...

  5. Supported lipid bilayers as templates to design manganese oxide ...

    Indian Academy of Sciences (India)

    Abstract. This work reports on the preparation of nanoclusters of manganese oxide using biotemplating techniques. Supported lipid bilayers (SLBs) on quartz using cationic lipid [Dioctadecyldimethylammonium bromide (DOMA)] and mixed systems with neutral phospholipids dipalmitoyl phosphatidylcholine (DPPC) and.

  6. Sub-wavelength antenna enhanced bilayer graphene tunable photodetector

    Science.gov (United States)

    Beechem, III, Thomas Edwin; Howell, Stephen W.; Peters, David W.; Davids, Paul; Ohta, Taisuke

    2016-03-22

    The integration of bilayer graphene with an absorption enhancing sub-wavelength antenna provides an infrared photodetector capable of real-time spectral tuning without filters at nanosecond timescales.

  7. Energy Spectrum and Quantum Hall Effect in Twisted Bilayer Graphene

    OpenAIRE

    Moon, Pilkyung; Koshino, Mikito

    2012-01-01

    We investigate the electronic spectra and quantum Hall effect in twisted bilayer graphenes with various rotation angles under magnetic fields, using a model rigorously including the interlayer interaction. We describe the spectral evolution from discrete Landau levels in the weak field regime to the fractal band structure in the strong field regime, and estimate the quantized Hall conductivity for each single gap. In weak magnetic fields, the low-energy conduction band of the twisted bilayer ...

  8. Magnetically Assisted Bilayer Composites for Soft Bending Actuators

    OpenAIRE

    Jang, Sung-Hwan; Na, Seon-Hong; Park, Yong-Lae

    2017-01-01

    This article presents a soft pneumatic bending actuator using a magnetically assisted bilayer composite composed of silicone polymer and ferromagnetic particles. Bilayer composites were fabricated by mixing ferromagnetic particles to a prepolymer state of silicone in a mold and asymmetrically distributed them by applying a strong non-uniform magnetic field to one side of the mold during the curing process. The biased magnetic field induces sedimentation of the ferromagnetic particles toward o...

  9. Single channel analysis of membrane proteins in artificial bilayer membranes.

    Science.gov (United States)

    Bartsch, Philipp; Harsman, Anke; Wagner, Richard

    2013-01-01

    The planar lipid bilayer technique is a powerful experimental approach for electrical single channel recordings of pore-forming membrane proteins in a chemically well-defined and easily modifiable environment. Here we provide a general survey of the basic materials and procedures required to set up a robust bilayer system and perform electrophysiological single channel recordings of reconstituted proteins suitable for the in-depth characterization of their functional properties.

  10. The edge engineering of topological Bi(111) bilayer

    OpenAIRE

    Li, Xiao; Liu, Hai-Wen; Jiang, Hua; Wang, Fa; Feng, Ji

    2014-01-01

    A topological insulator is a novel quantum state, characterized by symmetry-protected non-trivial edge/surface states. Our first-principle simulations show the significant effects of the chemical decoration on edge states of topological Bi(111) bilayer nanoribbon, which remove the trivial edge state and recover the Dirac linear dispersion of topological edge state. By comparing the edge states with and without chemical decoration, the Bi(111) bilayer nanoribbon offers a simple system for asse...

  11. Enhancing magnetoelectric effect in multiferroic composite bilayers via flexoelectricity

    Science.gov (United States)

    Zhang, Chunli; Zhang, Lingli; Shen, Xudong; Chen, Weiqiu

    2016-04-01

    We employ the flexoelectricity to enhance the magnetoelectric (ME) (coupling) effect in multiferroic (MF) composites and structures. An analytical model is presented to predict the ME effect in a MF composite bilayer consisting of piezomagnetic and piezoelectric layers. The flexoelectric effect in the piezoelectric layer is taken into account. The static ME effect in the MF composite bilayer with free boundary conditions is investigated. The results indicate that flexoelectricity can dramatically enhance the ME effect in multiferroic composites and structures.

  12. Pattern zoology in biaxially pre-stretched elastic bilayers: from wrinkles and creases to fracture-like ridges

    Science.gov (United States)

    Al-Rashed, Rashed; Lopez JiméNez, Francisco; Reis, Pedro

    The wrinkling of elastic bilayers under compression has been explored as a method to produce reversible surface topography, with applications ranging from microfluidics to tunable optics. We introduce a new experimental system to study the effects of pre-stretching on the instability patterns that result from the biaxial compression of thin shells bound to an elastic substrate. A pre-stretched substrate is first prepared by pressurizing an initially flat elastomeric disk and bulging it into a nearly hemispherical thick shell. The substrate is then coated with a thin layer of a polymer suspension, which, upon curing, results in a thin shell of nearly constant thickness. Releasing the pre-stretch in the substrate by deflating the system places the outer film in a state of biaxial compression, resulting in a variety of buckling patterns. We explore the parameter space by systematically varying the pre-stretch, the substrate/film stiffness mismatch, and the thickness of the film. This results in a continuous transition between different buckling patterns, from the dimples and wrinkles that are traditionally associated with the buckling of elastic bilayers, to creases and high aspect ratio `fracture-like' ridges, where the pre-stretch plays an essential role.

  13. Spin pumping in ion-beam sputtered C o2FeAl /Mo bilayers: Interfacial Gilbert damping

    Science.gov (United States)

    Husain, Sajid; Kumar, Ankit; Barwal, Vineet; Behera, Nilamani; Akansel, Serkan; Svedlindh, Peter; Chaudhary, Sujeet

    2018-02-01

    The spin-pumping mechanism and associated interfacial Gilbert damping are demonstrated in ion-beam sputtered C o2FeAl (CFA)/Mo bilayer thin films employing ferromagnetic resonance spectroscopy. The dependence of the net spin-current transportation on Mo layer thickness, 0 to 10 nm, and the enhancement of the net effective Gilbert damping are reported. The experimental data have been analyzed using spin-pumping theory in terms of spin current pumped through the ferromagnet/nonmagnetic metal interface to deduce the real spin-mixing conductance and the spin-diffusion length, which are estimated to be 1.56 (±0.30 ) ×1019m-2 and 2.61 (±0.15 )nm , respectively. The damping constant is found to be 8.8 (±0.2 ) ×10-3 in the Mo(3.5 nm)-capped CFA(8 nm) sample corresponding to an ˜69 % enhancement of the original Gilbert damping 5.2 (±0.6 ) ×10-3 in the Al-capped CFA thin film. This is further confirmed by inserting the Cu dusting layer which reduces the spin transport across the CFA/Mo interface. The Mo layer thickness-dependent net spin-current density is found to lie in the range of 1 -4 MA m-2 , which also provides additional quantitative evidence of spin pumping in this bilayer thin-film system.

  14. Bilayer interfacial properties modulate the binding of amphipathic peptides.

    Science.gov (United States)

    Allende, Daniel; Vidal, Adriana; Simon, Sidney A; McIntosh, Thomas J

    2003-01-01

    The free energy of transfer (DeltaG degrees ) from water to lipid bilayers was measured for two amphipathic peptides, the presequence of the mitochondrial peptide rhodanese (MPR) and melittin. Experiments were designed to determine the effects on peptide partitioning of the addition of lipids that produce structural modifications to the bilayer/water interface. In particular, the addition of cholesterol or the cholesterol analog 6-ketocholestanol increases the bilayer area compressibility modulus, indicating that these molecules modify lipid-lipid interactions in the plane of the bilayer. The addition of 6-ketocholestanol or lipids with attached polyethylene glycol chains (PEG-lipids) modify the effective thickness of the interfacial region; 6-ketocholestanol increases the width of hydrophilic headgroup region in the direction of the acyl chains whereas the protruding PEG chains of PEG-lipids increase the structural width of the headgroup region into the surrounding aqueous phase. The incorporation of PEG-lipids with PEG molecular weights of 2000 or 5000 had no appreciable effect on peptide partitioning that could not be accounted for by the presence of surface charge. However, for both MPR and melittin DeltaG degrees decreased linearly with increasing bilayer compressibility modulus, demonstrating the importance of bilayer mechanical properties in the binding of amphipathic peptides.

  15. Predicting proton titration in cationic micelle and bilayer environments

    Science.gov (United States)

    Morrow, Brian H.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.; Shen, Jana K.

    2014-08-01

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pKa's in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pKa of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pKa of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.

  16. Microporous device for local electric recordings on model lipid bilayers

    International Nuclear Information System (INIS)

    Kaufeld, Theresa; Schmidt, Christoph F; Steinem, Claudia

    2015-01-01

    A powerful approach for characterizing lipid membranes and embedded proteins is the reconstitution of model lipid bilayers. The extreme fragility of 5 nm thick bilayers is a challenge for device design and requires a trade off of stability against accessibility. We here present a microporous lab-on-chip device that allows us to form stable, solvent-free lipid bilayers from giant unilamellar vesicles (GUVs) in a geometry that provides a unique set of access possibilities. The device is constructed around a micro-fabricated silicon chip with clusters of 1 µm-diameter pores and provides optical access to the lipid bilayers for high-NA epifluorescence imaging. At the same time, solvent exchange is possible on both sides of the lipid bilayer. Complete coverage can be achieved with GUVs, so that voltages can be applied across the lipid bilayer and single-channel currents can be measured using external or integrated silver/silver chloride electrodes. We describe the micro-fabrication by standard cleanroom techniques and the characterization of the device by atomic force microscopy, scanning electron microscopy and impedance spectroscopy. In proof-of-concept experiments we demonstrate that the device is capable of low-noise, single-ion-channel recordings. (paper)

  17. Interface-mediation of lipid bilayer organization and dynamics.

    Science.gov (United States)

    Mize, Hannah E; Blanchard, G J

    2016-06-22

    We report on the morphology and dynamics of planar supported lipid bilayer structures as a function of pH and ionic strength of the aqueous overlayer. Supported lipid bilayers composed of three components (phosphocholine, sphingomyelin and cholesterol) are known to exhibit phase segregation, with the characteristic domain sizes dependent on the amount and identity of each constituent, and the composition of the aqueous overlayer in contact with the bilayer. We report on fluorescence anisotropy decay imaging measurements of a rhodamine chromophore tethered to the headgroup of a phosphoethanolamine, where anisotropy decay images were acquired as a function of solution overlayer pH and ionic strength. The data reveal a two-component anisotropy decay under all conditions, with the faster time constant being largely independent of pH and ionic strength and the slower component depending on pH and ionic strength in different manners. For liposomes of the same composition, a single exponential anisotropy decay was seen. We interpret this difference in terms of bilayer curvature and support surface-bilayer interactions, and the pH and ionic strength dependencies in terms of ionic screening and protonation in the bilayer headgroup region.

  18. Robustly Engineering Thermal Conductivity of Bilayer Graphene by Interlayer Bonding

    Science.gov (United States)

    Zhang, Xiaoliang; Gao, Yufei; Chen, Yuli; Hu, Ming

    2016-01-01

    Graphene and its bilayer structure are the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. Their realistic applications in emerging nanoelectronics usually call for thermal transport manipulation in a controllable and precise manner. In this paper we systematically studied the effect of interlayer covalent bonding, in particular different interlay bonding arrangement, on the thermal conductivity of bilayer graphene using equilibrium molecular dynamics simulations. It is revealed that, the thermal conductivity of randomly bonded bilayer graphene decreases monotonically with the increase of interlayer bonding density, however, for the regularly bonded bilayer graphene structure the thermal conductivity possesses unexpectedly non-monotonic dependence on the interlayer bonding density. The results suggest that the thermal conductivity of bilayer graphene depends not only on the interlayer bonding density, but also on the detailed topological configuration of the interlayer bonding. The underlying mechanism for this abnormal phenomenon is identified by means of phonon spectral energy density, participation ratio and mode weight factor analysis. The large tunability of thermal conductivity of bilayer graphene through rational interlayer bonding arrangement paves the way to achieve other desired properties for potential nanoelectronics applications involving graphene layers. PMID:26911859

  19. Effect of annealing process on TiN/TiC bilayers grown by pulsed arc discharge

    International Nuclear Information System (INIS)

    Ramos-Rivera, L.; Escobar, D.; Benavides-Palacios, V.; Arango, P.J.; Restrepo-Parra, E.

    2012-01-01

    In this work, a study of annealing process effect on TiN/TiC bilayer is presented. The annealing temperature was varied between room temperature and 500 °C. Materials were produced by the plasma-assisted pulsed vacuum arc discharge technique. In order to grow the films, a target of Ti with 99.9999% purity and stainless-steel 304 substrate were used. For the production of TiN layer, the reaction chamber was filled up with nitrogen gas until reaching 25 Pa and the discharge was performed at 310 V. The TiC layer was grown in a methane atmosphere at 30 Pa and 270 V. X-ray diffraction and X photoelectron spectroscopy were employed for studying the structure and chemical composition evolution during the annealing process. At 400 °C, TiO 2 phase begun to appear and it was well observed at 500 °C. Crystallite size and microstrain was obtained as a function of the annealing temperature. XPS technique was employed for analyzing the bilayers before and after the annealing process. Narrow spectra of Ti2p, N1s and O1s were obtained, presenting TiO phases.

  20. Focused-ion-beam induced interfacial intermixing of magnetic bilayers for nanoscale control of magnetic properties

    International Nuclear Information System (INIS)

    Burn, D M; Atkinson, D; Hase, T P A

    2014-01-01

    Modification of the magnetic properties in a thin-film ferromagnetic/non-magnetic bilayer system by low-dose focused ion-beam (FIB) induced intermixing is demonstrated. The highly localized capability of FIB may be used to locally control magnetic behaviour at the nanoscale. The magnetic, electronic and structural properties of NiFe/Au bilayers were investigated as a function of the interfacial structure that was actively modified using focused Ga + ion irradiation. Experimental work used MOKE, SQUID, XMCD as well as magnetoresistance measurements to determine the magnetic behavior and grazing incidence x-ray reflectivity to elucidate the interfacial structure. Interfacial intermixing, induced by low-dose irradiation, is shown to lead to complex changes in the magnetic behavior that are associated with monotonic structural evolution of the interface. This behavior may be explained by changes in the local atomic environment within the interface region resulting in a combination of processes including the loss of moment on Ni and Fe, an induced moment on Au and modifications to the spin-orbit coupling between Au and NiFe. (paper)

  1. Effect of annealing process on TiN/TiC bilayers grown by pulsed arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Rivera, L., E-mail: lramosr@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Aeropuerto Campus La Nubia (Colombia); Escobar, D.; Benavides-Palacios, V.; Arango, P.J.; Restrepo-Parra, E. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Aeropuerto Campus La Nubia (Colombia)

    2012-08-15

    In this work, a study of annealing process effect on TiN/TiC bilayer is presented. The annealing temperature was varied between room temperature and 500 Degree-Sign C. Materials were produced by the plasma-assisted pulsed vacuum arc discharge technique. In order to grow the films, a target of Ti with 99.9999% purity and stainless-steel 304 substrate were used. For the production of TiN layer, the reaction chamber was filled up with nitrogen gas until reaching 25 Pa and the discharge was performed at 310 V. The TiC layer was grown in a methane atmosphere at 30 Pa and 270 V. X-ray diffraction and X photoelectron spectroscopy were employed for studying the structure and chemical composition evolution during the annealing process. At 400 Degree-Sign C, TiO{sub 2} phase begun to appear and it was well observed at 500 Degree-Sign C. Crystallite size and microstrain was obtained as a function of the annealing temperature. XPS technique was employed for analyzing the bilayers before and after the annealing process. Narrow spectra of Ti2p, N1s and O1s were obtained, presenting TiO phases.

  2. ZnO/CdS bi-layer nanostructures photoelectrode for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dalal, Paresh V., E-mail: paresh10dalal@gmail.com [Physics Research Lab, Shri V. S. Naik Arts, Commerce and Science College, Raver-425508 (M. S.) (India); Deshpande, Milind P., E-mail: vishwadeshpande@yahoo.co.in [Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388120 (Gujarat) (India); Solanki, Bharat G., E-mail: bhrt.solanki17@gmail.com; Soni, Saurabh S., E-mail: soni-b21@yahoo.co.in [Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar-388120 (Gujarat) (India)

    2016-05-06

    Simple chemical deposition method for the synthesis of ZnO/CdS bilayer photoelectrode on fluorine doped tin oxide (FTO) coated glass substrate in aqueous medium at low temperature (< 373K) is described. The different preparative parameters such as deposition time, bath temperature, concentration of precursor solution and, pH of the bath etc. were optimized. Nanograined ZnO was deposited on FTO coated glass substrates by dip-coating method, whereas CdS nanorods were successfully synthesized on pre-deposited ZnO film by Chemical Bath Deposition (CBD) method. The Photovoltaic properties of FTO/ZnO/CdS bilayer photo electrodes were also studied. A maximum short circuit current density of 9.1 mA cm-2 and conversion efficiency 1.05% are observed for ZnO/CdS-10min. Layer, which supports fast electron injection kinetics due to hetero structured nanorod, while minimum values of 0.53mA cm-2 and 0.01% respectively are observed for only ZnO deposited layer.

  3. Improvement of the effective work function and transmittance of thick indium tin oxide/ultrathin ruthenium doped indium oxide bilayers as transparent conductive oxide

    Energy Technology Data Exchange (ETDEWEB)

    Taweesup, Kattareeya [Department of Metallurgical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Yamamoto, Ippei [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Shibaura Institute of Technology, 3-7-5 Toyosu, Koto, Tokyo 135-8548 (Japan); Chikyow, Toyohiro [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Lothongkum, Gobboon [Department of Metallurgical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Tsukagoshi, Kazutoshi [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Ohishi, Tomoji [Shibaura Institute of Technology, 3-7-5 Toyosu, Koto, Tokyo 135-8548 (Japan); Tungasmita, Sukkaneste [Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Visuttipitukul, Patama [Department of Metallurgical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Ito, Kazuhiro; Takahashi, Makoto [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Nabatame, Toshihide, E-mail: NABATAME.Toshihide@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2016-01-01

    Ruthenium doped indium oxide (In{sub 1−x}Ru{sub x}O{sub y}) films fabricated using DC magnetron co-sputtering with In{sub 2}O{sub 3} and Ru targets were investigated for use as transparent conductive oxides. The In{sub 1−x}Ru{sub x}O{sub y} films had an amorphous structure in the wide compositional range of x = 0.3–0.8 and had an extremely smooth surface. The transmittance and resistivity of the In{sub 1−x}Ru{sub x}O{sub y} films increased as the Ru content increased. The transmittance of the In{sub 0.38}Ru{sub 0.62}O{sub y} film improved to over 80% when the film thickness was less than 5 nm, while the specific resistivity (ρ) was kept to a low value of 1.6 × 10{sup −4} Ω cm. Based on these experimental data, we demonstrated that thick indium tin oxide (In{sub 0.9}Sn{sub 0.1}O{sub y}, ITO) (150 nm)/ultrathin In{sub 0.38}Ru{sub 0.62}O{sub y} (3 nm) bilayers have a high effective work function of 5.3 eV, transmittance of 86%, and low ρ of 9.2 × 10{sup −5} Ω cm. This ITO/In{sub 0.38}Ru{sub 0.62}O{sub y} bilayer is a candidate for use as an anode for organic electroluminescent devices. - Highlights: • We investigated characteristics of thick ITO/ultrathin Ru doped In{sub 2}O{sub 3} bilayers. • Effect of Ru addition in In{sub 2}O{sub 3} results in smooth surface because of an amorphous structure. • The In{sub 0.38}Ru{sub 0.62}O{sub y} film with less than 5 nm improves to high transmittance over 80%. • ITO/In{sub 0.38}Ru{sub 0.62}O{sub y} bilayer has a high effective work function of 5.3 eV. • We conclude that ITO/ultrathin In{sub 0.38}Ru{sub 0.62}O{sub y} bilayer is a candidate as an anode of OEL.

  4. Thickness dependence study of current-driven ferromagnetic resonance in Y3Fe5O12/heavy metal bilayers

    Science.gov (United States)

    Fang, Z.; Mitra, A.; Westerman, A. L.; Ali, M.; Ciccarelli, C.; Cespedes, O.; Hickey, B. J.; Ferguson, A. J.

    2017-02-01

    We use ferromagnetic resonance to study the current-induced torques in YIG/heavy metal bilayers. YIG samples with thickness varying from 14.8 nm to 80 nm, with the Pt or Ta thin film on top, are measured by applying a microwave current into the heavy metals and measuring the longitudinal DC voltage generated by both spin rectification and spin pumping. From a symmetry analysis of the FMR lineshape and its dependence on YIG thickness, we deduce that the Oersted field dominates over spin-transfer torque in driving magnetization dynamics.

  5. Fabrication and characterization of an integrated ionic device from suspended polypyrrole and alamethicin-reconstituted lipid bilayer membranes

    International Nuclear Information System (INIS)

    Northcutt, Robert; Sundaresan, Vishnu-Baba

    2012-01-01

    Conducting polymers are electroactive materials that undergo conformal relaxation of the polymer backbone in the presence of an electrical field through ion exchange with solid or aqueous electrolytes. This conformal relaxation and the associated morphological changes make conducting polymers highly suitable for actuation and sensing applications. Among smart materials, bioderived active materials also use ion transport for sensing and actuation functions via selective ion transport. The transporter proteins extracted from biological cell membranes and reconstituted into a bilayer lipid membrane in bioderived active materials regulate ion transport for engineering functions. The protein transporter reconstituted in the bilayer lipid membrane is referred to as the bioderived membrane and serves as the active component in bioderived active materials. Inspired by the similarities in the physics of transduction in conducting polymers and bioderived active materials, an integrated ionic device is formed from the bioderived membrane and the conducting polymer membrane. This ionic device is fabricated into a laminated thin-film membrane and a common ion that can be processed by the bioderived and the conducting polymer membranes couple the ionic function of these two membranes. An integrated ionic device, fabricated from polypyrrole (PPy) doped with sodium dodecylbenzenesulfonate (NaDBS) and an alamethicin-reconstituted DPhPC bilayer lipid membrane, is presented in this paper. A voltage-gated sodium current regulates the electrochemical response in the PPy(DBS) layer. The integrated device is fabricated on silicon-based substrates through microfabrication, electropolymerization, and vesicle fusion, and ionic activity is characterized through electrochemical measurements. (paper)

  6. Evaluation of Double Process Lithography (DPL) with bi-layer photo-resist process for contact layer-patterning

    Science.gov (United States)

    Chen, Gong; Wu, Kevin

    2008-10-01

    Double Process Lithography (DPL) has been widely accepted as a viable printing technique for critical layers at 45nm nodes and below. In addition, DPL technique also allows us to use available process tool-sets with less capability to develop the next node CMOS devices in early research and development stages with additional photo-masks. One practical issue of applying DPL technique is the process crosstalk, which is the impact of the existing etched patterns after the 1st process to the overall lithography performance during the 2nd printing process. In this paper, we evaluated the DPL process for contact holetype patterning with a 193nm silicon-containing bi-layer photo-resist. We explained the bi-layer photoresist process flow and its low process cross-talk characteristics when applied in our DPL process. We also discussed the challenges of printing small contacts in the DPL process. The preliminary experiment results indicated that silicon-containing photo-resist process is a good candidate for DPL process in the contact hole-type of patterns, and it has good characteristics of low process cross-talk. The flexibility of the drydevelop process in bi-layer resist also offered us another way to form small contacts in the substrate film. At the end, we provided some suggestions in contact pattern decomposition algorithm and related exposure-tool alignment strategies for future implementation of DPL technology.

  7. Inverse relation of exchange-bias and coercivity in epitaxial bilayer of double ruthenate perovskites

    Science.gov (United States)

    Eswara Phanindra, V.; Das, Sarmistha; Singh, R. P.; Rana, D. S.

    2018-03-01

    We report observation of exchange bias (EB) field manifesting in the bilayer thin film of SrRuO3 (SRO) in a rare combination with double perovskite Sr2YRuO6 (SYRO) grown on SrTiO3 (100) substrate. From the temperature and cooling field dependence of exchange bias (HEB) and coercive field (HC), we found an anomalous correlation of these two properties in the temperature range of 15–30 K; the HEB decreases while HC increases with increasing temperature. This anomaly along with the disappearance of the HEB points towards the role of spin fluctuations near the blocking temperature. A good agreement of training effect data with various theoretical models, in turn, supports that the EB derived from the geometrically frustrated interfaces involving double perovskites has generic features as well.

  8. Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

    Directory of Open Access Journals (Sweden)

    Bing Huang

    2014-05-01

    Full Text Available Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single- and double-sided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high-efficiency, optoelectronic applications.

  9. Edge effects in Bilayer Graphene Nanoribbons

    Science.gov (United States)

    Lima, Matheus P.; Fazzio, Adalberto; da Silva, Antonio J. R.

    2009-03-01

    We investigate the geometrical and electronic structure of zigzag bilayer graphene nanoribbons (B-ZGNR), with widths that range from w=0.6 to w=4.5 nm. The layers are in the Bernal stacking, which means that there are two types of C atoms, those that are positioned above the center of the hexagons of the other layer, defining a B-sublattice, and those right on top of the C atoms of the other layer, forming an A-sublattice. When we cut the layer along the zigzag edge, there are two possible alignments, α, where the outermost edge atoms belong to the A- sublattice, and β, where the outermost edge atoms belong to the B-sublattice. Thus, only the inter-layer edge interaction differs. We found that the α alignment is energetically favorable, with an inter-layer edges attraction, whereas for the β there is an inter-layer edges repulsion. These edge-related forces cause a deviation from the exact Bernal stacking, resulting in a non-monotonic behavior of the energy gap with the width w for the α B-ZGNR, with a maximum value at w 3.5nm. This is a consequence of the competition between bulk and strongly attractive edge interactions. All results were obtained using density functional theory calculations with the inclusion of parametrized van der Waals interactions.

  10. Observation of undulation motion of lipid bilayers by neutron spin echo

    International Nuclear Information System (INIS)

    Yamada, Norifumi L.; Seto, Hideki; Hishida, Mafumi

    2010-01-01

    Aqueous solutions of synthesized phospholipids have been well investigated as model biomembranes. These lipids usually self-assemble into regular stacks of bilayers with a characteristic repeat distance on the order of nm, whereas real biomembrane exist as single bilayers. The key phenomenon in understanding the formation of single isolated bilayers in 'unbinding' of lipid bilayers, in which the inter-bilayer distance of lipid bilayers diverges by the steric interaction due to the membrane undulation. In this paper, we show some results of neutron spin-echo (NSE) experiments to investigate the effect of the steric interaction on unbinding and related phenomena. (author)

  11. Deposit of bilayers of LiNiO2/alumina by laser ablation

    International Nuclear Information System (INIS)

    Lopez I, J.; Escobar A, L.; Camps, E.; Camacho L, M.E.

    2006-01-01

    Thin films of lithium nickel oxide (LiNiO 2 ) were deposited on silicon substrates at two substrate temperatures: ambient temperature and 165 C ; varying in each case the fluence from 3 up to 20 J/cm 2 . The used target got ready starting from the solid state reaction between NiO and Li 2 O this last in excess of 50% in weight, with the purpose of obtaining stoichiometric LiNiO 2 . Later to the deposit it was carried out a thermal treatment to all the films at 300 C by 2 hours, with the purpose of improving the crystalline structure of the deposited material. The deposits were analyzed by Raman spectroscopy, showing for all the films a wide band with a maximum approximately in 550 cm -1 for the deposits not thermally treated and in 500 cm -1 for the deposits with thermal treatment. Bilayers of LiNiO 2 /Al 2 O 3 were deposited, to be used as cathode material in rechargeable micro batteries, those results of the Raman spectroscopy didn't show variation in the intensity, position and wide of the band shown for the LiNiO 2 . On the other hand the deposits were also analyzed by infrared spectroscopy with the purpose of confirming the Raman results. (Author)

  12. Bilayer sheet protrusions and budding from bilayer membranes induced by hydrolysis and condensation reactions

    Science.gov (United States)

    Nakagawa, Koh M.; Noguchi, Hiroshi

    Shape transformations of flat bilayer membranes and vesicles induced by hydrolysis and condensation reactions of amphiphilic molecules are studied using coarse-grained molecular dynamics simulations. The hydrolysis and condensation reactions result in the formation and dissociation of amphiphilic molecules, respectively. Asymmetric reactions between the inner and outer leaflets of a vesicle can transport amphiphilic molecules between the leaflets. It is found that the resulting area difference between the two leaflets induces bilayer sheet protrusion~(BP) and budding at low reduced volumes of the vesicles, whereas BP only occurs at high reduced volumes. The probabilities of these two types of transformations depend on the shear viscosity of the surrounding fluids compared to the membrane as well as the reaction rates. A higher surrounding fluid viscosity leads to more BP formation. The inhomogeneous spatial distribution of the hydrophobic reaction products forms the nuclei of BP formation, and faster diffusion of the products enhances BP formation. Our results suggest that adjustment of the viscosity is important to control membrane shape transformations in experiments.

  13. Direct transfer of graphene films for polyurethane substrate

    International Nuclear Information System (INIS)

    Vilani, C.; Romani, E.C.; Larrudé, D.G.; Barbosa, Gelza M.; Freire, F.L.

    2015-01-01

    Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

  14. Direct transfer of graphene films for polyurethane substrate

    Energy Technology Data Exchange (ETDEWEB)

    Vilani, C.; Romani, E.C.; Larrudé, D.G. [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Barbosa, Gelza M. [Diretoria de Sistemas de Armas da Marinha, Marinha do Brasil, 20010-00 Rio de Janeiro, RJ (Brazil); Freire, F.L., E-mail: lazaro@vdg.fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

    2015-11-30

    Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

  15. Effects of accelerated degradation on metal supported thin film-based solid oxide fuel cell

    DEFF Research Database (Denmark)

    Reolon, R. P.; Sanna, S.; Xu, Yu

    2018-01-01

    A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte and nanostruct......A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte...

  16. Anomalous conductivity noise in gapped bilayer graphene heterostructure

    Science.gov (United States)

    Aamir, Mohammed Ali; Karnatak, Paritosh; Sai, T. Phanindra; Ghosh, Arindam

    Bilayer graphene has unique electronic properties - it has a tunable band gap and also, valley symmetry and pseudospin degree of freedom like its single layer counterpart. In this work, we present a study of conductance fluctuations in dual gated bilayer graphene heterostructures by varying the Fermi energy and the band gap independently. At a fixed band gap, we find that the conductance fluctuations obtained by Fermi energy ensemble sampling increase rapidly as the Fermi energy is tuned to charge neutrality point (CNP) whereas the time-dependent conductance fluctuations diminish rapidly. This discrepancy is completely absent at higher number densities, where the transport is expected to be through the 2D bulk of the bilayer system. This observation indicates that near the CNP, electrical transport is highly sensitive to Fermi energy, but becomes progressively immune to time-varying disorder. A possible explanation may involve transport via edge states which becomes the dominant conduction mechanism when the bilayer graphene is gapped and Fermi energy is situated close to the CNP, thereby causing a dimensional crossover from 2D to 1D transport. Our experiment outlines a possible experimental protocol to probe intrinsic topological states in gapped bilayer graphene.

  17. Gas Separation through Bilayer Silica, the Thinnest Possible Silica Membrane.

    Science.gov (United States)

    Yao, Bowen; Mandrà, Salvatore; Curry, John O; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Schrier, Joshua

    2017-12-13

    Membrane-based gas separation processes can address key challenges in energy and environment, but for many applications the permeance and selectivity of bulk membranes is insufficient for economical use. Theory and experiment indicate that permeance and selectivity can be increased by using two-dimensional materials with subnanometer pores as membranes. Motivated by experiments showing selective permeation of H 2 /CO mixtures through amorphous silica bilayers, here we perform a theoretical study of gas separation through silica bilayers. Using density functional theory calculations, we obtain geometries of crystalline free-standing silica bilayers (comprised of six-membered rings), as well as the seven-, eight-, and nine-membered rings that are observed in glassy silica bilayers, which arise due to Stone-Wales defects and vacancies. We then compute the potential energy barriers for gas passage through these various pore types for He, Ne, Ar, Kr, H 2 , N 2 , CO, and CO 2 gases, and use the data to assess their capability for selective gas separation. Our calculations indicate that crystalline bilayer silica, which is less than a nanometer thick, can be a high-selectivity and high-permeance membrane material for 3 He/ 4 He, He/natural gas, and H 2 /CO separations.

  18. Tensile and shear methods for measuring strength of bilayer tablets.

    Science.gov (United States)

    Chang, Shao-Yu; Li, Jian-Xin; Sun, Changquan Calvin

    2017-05-15

    Both shear and tensile measurement methods have been used to quantify interfacial bonding strength of bilayer tablets. The shear method is more convenient to perform, but reproducible strength data requires careful control of the placement of tablet and contact point for shear force application. Moreover, data obtained from the shear method depend on the orientation of the bilayer tablet. Although more time-consuming to perform, the tensile method yields data that are straightforward to interpret. Thus, the tensile method is preferred in fundamental bilayer tableting research to minimize ambiguity in data interpretation. Using both shear and tensile methods, we measured the mechanical strength of bilayer tablets made of several different layer combinations of lactose and microcrystalline cellulose. We observed a good correlation between strength obtained by the tensile method and carefully conducted shear method. This suggests that the shear method may be used for routine quality test of bilayer tablets during manufacturing because of its speed and convenience, provided a protocol for careful control of the placement of the tablet interface, tablet orientation, and blade is implemented. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Spin-Coating and Characterization of Multiferroic MFe{sub 2}O{sub 4} (M=Co, Ni) / BaTiO{sub 3} Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Quandt, Norman [Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 2, 06120 Halle (Germany); Roth, Robert [Institute of Physics, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle (Germany); Syrowatka, Frank [Interdisciplinary Center of Materials Science, Martin Luther University Halle-Wittenberg, Heinrich-Damerow-Straße 4, 06120 Halle (Germany); Steimecke, Matthias [Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Germany); Ebbinghaus, Stefan G., E-mail: stefan.ebbinghaus@chemie.uni-halle.de [Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 2, 06120 Halle (Germany)

    2016-01-15

    Bilayer films of MFe{sub 2}O{sub 4} (M=Co, Ni) and BaTiO{sub 3} were prepared by spin coating of N,N-dimethylformamide/acetic acid solutions on platinum coated silicon wafers. Five coating steps were applied to get the desired thickness of 150 nm for both the ferrite and perovskite layer. XRD, IR and Raman spectroscopy revealed the formation of phase-pure ferrite spinels and BaTiO{sub 3}. Smooth surfaces with roughnesses in the order of 3 to 5 nm were found in AFM investigations. Saturation magnetization of 347 emu cm{sup −3} for the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} and 188 emu cm{sup −3} for the NiFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer, respectively were found. For the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer a strong magnetic anisotropy was observed with coercivity fields of 5.1 kOe and 3.3 kOe (applied magnetic field perpendicular and parallel to film surface), while for the NiFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer this effect is less pronounced. Saturated polarization hysteresis loops prove the presence of ferroelectricity in both systems. - Graphical abstract: The SEM image of the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer on Pt–Si-substrate (left), magnetization as a function of the magnetic field perpendicular and parallel to the film plane (right top) and P–E and I–V hysteresis loops of the bilayer at room temperature. - Highlights: • Ferrite and perovskite oxides grown on platinum using spin coating technique. • Columnar growth of cobalt ferrite particle on the substrate. • Surface investigation showed a homogenous and smooth surface. • Perpendicular and parallel applied magnetic field revealed a magnetic anisotropy. • Switching peaks and saturated P–E hysteresis loops show ferroelectricity.

  20. Schottky Barriers in Bilayer Phosphorene Transistors.

    Science.gov (United States)

    Pan, Yuanyuan; Dan, Yang; Wang, Yangyang; Ye, Meng; Zhang, Han; Quhe, Ruge; Zhang, Xiuying; Li, Jingzhen; Guo, Wanlin; Yang, Li; Lu, Jing

    2017-04-12

    It is unreliable to evaluate the Schottky barrier height (SBH) in monolayer (ML) 2D material field effect transistors (FETs) with strongly interacted electrode from the work function approximation (WFA) because of existence of the Fermi-level pinning. Here, we report the first systematical study of bilayer (BL) phosphorene FETs in contact with a series of metals with a wide work function range (Al, Ag, Cu, Au, Cr, Ti, Ni, and Pd) by using both ab initio electronic band calculations and quantum transport simulation (QTS). Different from only one type of Schottky barrier (SB) identified in the ML phosphorene FETs, two types of SBs are identified in BL phosphorene FETs: the vertical SB between the metallized and the intact phosphorene layer, whose height is determined from the energy band analysis (EBA); the lateral SB between the metallized and the channel BL phosphorene, whose height is determined from the QTS. The vertical SBHs show a better consistency with the lateral SBHs of the ML phosphorene FETs from the QTS compared than that of the popular WFA. Therefore, we develop a better and more general method than the WFA to estimate the lateral SBHs of ML semiconductor transistors with strongly interacted electrodes based on the EBA for its BL counterpart. In terms of the QTS, n-type lateral Schottky contacts are formed between BL phosphorene and Cr, Al, and Cu electrodes with electron SBH of 0.27, 0.31, and 0.32 eV, respectively, while p-type lateral Schottky contacts are formed between BL phosphorene and Pd, Ti, Ni, Ag, and Au electrodes with hole SBH of 0.11, 0.18, 0.19, 0.20, and 0.21 eV, respectively. The theoretical polarity and SBHs are in good agreement with available experiments. Our study provides an insight into the BL phosphorene-metal interfaces that are crucial for designing the BL phosphorene device.

  1. Prestresses in bilayered all-ceramic restorations.

    Science.gov (United States)

    Aboushelib, Moustafa N; Feilzer, Albert J; de Jager, Niek; Kleverlaan, Cornelis J

    2008-10-01

    A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+DeltaTEC). The concept behind this TEC mismatch is to generate compressive stresses in the weaker veneering ceramic and thus enhance the overall strength of the restoration. This technique had excellent results with porcelain fused to metal restorations (PFM). However, there are concerns to apply this concept to all-ceramic restorations. The aim of this research was to determine the stresses in bilayered all-ceramic restorations due to the mismatch in TEC. Two commercial veneering ceramics with a TEC lower than that of zirconia (+DeltaTEC); NobelRondo zirconiatrade mark and Lava Ceramtrade mark, plus one experimental veneering ceramic with an identical TEC that matches that of zirconia (DeltaTEC = 0) were used to veneer zirconia discs. The specimens were loaded in biaxial flexure test setup with the veneer ceramic in tension. The stresses due to load application and TEC mismatch were calculated using fractography, engineering mathematics, and finite element analysis (FEA). In this study, the highest load at failure (64 N) was obtained with the experimental veneer where the thermal mismatch between zirconia and veneering ceramic was minimal. For the two commercial veneer ceramics the magnitude of the thermal mismatch localized at the zirconia veneer interface (42 MPa) exceeded the bond strength between the two materials and resulted in delamination failure during testing (ca. 50 MPa). For all-ceramic zirconia veneered restorations it is recommended to minimize the thermal mismatch as much as possible. (c) 2008 Wiley Periodicals, Inc.

  2. The Role of Nonlinear Substrate Elasticity in the Wrinkling of Thin Films

    OpenAIRE

    Hutchinson, John W.

    2013-01-01

    The role of substrate nonlinearity on the stability of wrinkling of thin films bonded to compliant substrates is investigated within the initial post-bifurcation range when wrinkling first emerges. A fully nonlinear neo-Hookean bilayer composed of a thin film on a deep substrate is analyzed for a wide range of the film/substrate stiffness ratio, from films that are very stiff compared to the substrate to those only slightly stiffer. Substrate pre-stretch prior to film attachment is shown to h...

  3. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers

    KAUST Repository

    Springer, D.

    2016-02-12

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  4. Assessment of pseudo-bilayer structures in the heterogate germanium electron-hole bilayer tunnel field-effect transistor

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, J. L., E-mail: jose.padilladelatorre@epfl.ch; Alper, C.; Ionescu, A. M. [Nanoelectronic Devices Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne CH-1015 (Switzerland); Medina-Bailón, C.; Gámiz, F. [Departamento de Electrónica y Tecnología de los Computadores, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada (Spain)

    2015-06-29

    We investigate the effect of pseudo-bilayer configurations at low operating voltages (≤0.5 V) in the heterogate germanium electron-hole bilayer tunnel field-effect transistor (HG-EHBTFET) compared to the traditional bilayer structures of EHBTFETs arising from semiclassical simulations where the inversion layers for electrons and holes featured very symmetric profiles with similar concentration levels at the ON-state. Pseudo-bilayer layouts are attained by inducing a certain asymmetry between the top and the bottom gates so that even though the hole inversion layer is formed at the bottom of the channel, the top gate voltage remains below the required value to trigger the formation of the inversion layer for electrons. Resulting benefits from this setup are improved electrostatic control on the channel, enhanced gate-to-gate efficiency, and higher I{sub ON} levels. Furthermore, pseudo-bilayer configurations alleviate the difficulties derived from confining very high opposite carrier concentrations in very thin structures.

  5. Light-Patterned Current Generation in a Droplet Bilayer Array

    Science.gov (United States)

    Restrepo Schild, Vanessa; Booth, Michael J.; Box, Stuart J.; Olof, Sam N.; Mahendran, Kozhinjampara R.; Bayley, Hagan

    2017-04-01

    We have created a 4 × 4 droplet bilayer array comprising light-activatable aqueous droplet bio-pixels. Aqueous droplets containing bacteriorhodopsin (bR), a light-driven proton pump, were arranged on a common hydrogel surface in lipid-containing oil. A separate lipid bilayer formed at the interface between each droplet and the hydrogel; each bilayer then incorporated bR. Electrodes in each droplet simultaneously measured the light-driven proton-pumping activities of each bio-pixel. The 4 × 4 array derived by this bottom-up synthetic biology approach can detect grey-scale images and patterns of light moving across the device, which are transduced as electrical current generated in each bio-pixel. We propose that synthetic biological light-activatable arrays, produced with soft materials, might be interfaced with living tissues to stimulate neuronal pathways.

  6. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    International Nuclear Information System (INIS)

    Bradshaw, J.P.; Gilchrist, P.J.; Duff, K.C.; Saxena, A.M.

    1994-01-01

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein

  7. Formation and characterization of artificial lipid bilayers on optical fibers

    Science.gov (United States)

    Toussaint, Pauline; Dreesen, Laurent

    Transports across cellular membranes are at the basis of a lot of biological processes such as the transmission of information in neurons. Their characterization is therefore of crucial interest. As they are equivalent to biological membranes, artificial lipid bilayers can be created to study membranes and transmembrane proteins properties or transmembrane transports. The aim of this work is to develop a new method for the fabrication of artificial membranes, based on the use of optical fibers as support for the bilayer, and for their characterization by fluorescence measurements. We use microfluidics on fibers to create two phospholipid monolayers that we approach close enough to form a bilayer. The membrane formation is checked using fluorescein or a fluorescent sodium probe, Tetra (tetramethylammonium) salt (sodium green), whose optical signal depends on sodium concentration.

  8. Magnetically Assisted Bilayer Composites for Soft Bending Actuators

    Science.gov (United States)

    Jang, Sung-Hwan; Na, Seon-Hong; Park, Yong-Lae

    2017-01-01

    This article presents a soft pneumatic bending actuator using a magnetically assisted bilayer composite composed of silicone polymer and ferromagnetic particles. Bilayer composites were fabricated by mixing ferromagnetic particles to a prepolymer state of silicone in a mold and asymmetrically distributed them by applying a strong non-uniform magnetic field to one side of the mold during the curing process. The biased magnetic field induces sedimentation of the ferromagnetic particles toward one side of the structure. The nonhomogeneous distribution of the particles induces bending of the structure when inflated, as a result of asymmetric stiffness of the composite. The bilayer composites were then characterized with a scanning electron microscopy and thermogravimetric analysis. The bending performance and the axial expansion of the actuator were discussed for manipulation applications in soft robotics and bioengineering. The magnetically assisted manufacturing process for the soft bending actuator is a promising technique for various applications in soft robotics. PMID:28773007

  9. Magnetically Assisted Bilayer Composites for Soft Bending Actuators

    Directory of Open Access Journals (Sweden)

    Sung-Hwan Jang

    2017-06-01

    Full Text Available This article presents a soft pneumatic bending actuator using a magnetically assisted bilayer composite composed of silicone polymer and ferromagnetic particles. Bilayer composites were fabricated by mixing ferromagnetic particles to a prepolymer state of silicone in a mold and asymmetrically distributed them by applying a strong non-uniform magnetic field to one side of the mold during the curing process. The biased magnetic field induces sedimentation of the ferromagnetic particles toward one side of the structure. The nonhomogeneous distribution of the particles induces bending of the structure when inflated, as a result of asymmetric stiffness of the composite. The bilayer composites were then characterized with a scanning electron microscopy and thermogravimetric analysis. The bending performance and the axial expansion of the actuator were discussed for manipulation applications in soft robotics and bioengineering. The magnetically assisted manufacturing process for the soft bending actuator is a promising technique for various applications in soft robotics.

  10. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  11. Bilayer Deformation, Pores, and Micellation Induced by Oxidized Lipids.

    Science.gov (United States)

    Boonnoy, Phansiri; Jarerattanachat, Viwan; Karttunen, Mikko; Wong-Ekkabut, Jirasak

    2015-12-17

    The influence of different oxidized lipids on lipid bilayers was investigated with 16 individual 1 μs atomistic molecular dynamics (MD) simulations. Binary mixtures of lipid bilayers of 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC) and its peroxide and aldehyde products were performed at different concentrations. In addition, an asymmetrical short chain lipid, 1-palmitoyl-2-decanoyl-sn-glycero-3-phosphatidylcholine (PDPC), was used to compare the effects of polar/apolar groups in the lipid tail on lipid bilayer. Although water defects occurred with both aldehyde and peroxide lipids, full pore formation was observed only for aldehyde lipids. At medium concentrations the pores were stable. At higher concentrations, however, the pores became unstable and micellation occurred. Data analysis shows that aldehyde lipids' propensity for pore formation is due to their shorter and highly mobile tail. The highly polar peroxide lipids are stabilized by strong hydrogen bonds with interfacial water.

  12. Structure and tribological behavior of Pb-Ti/MoS2 nanoscaled multilayer films deposited by magnetron sputtering method

    Science.gov (United States)

    Li, Hao; Xie, Mingling; Zhang, Guangan; Fan, Xiaoqiang; Li, Xia; Zhu, Minhao; Wang, Liping

    2018-03-01

    The Pb-Ti/MoS2 nanoscaled multilayer films with different bilayer period were deposited by unbalanced magnetron sputtering system. The morphology, microstructure, mechanical and tribological properties of the films were investigated. It was found that the film changed from multilayer structure to composite structure as the bilayer period decreased from 25 nm to 6 nm, due to the diffusion effect. The multilayer film showed a pronounced (002) diffraction peak, the growth of the MoS2 platelets below the interface were affected by Pb and Ti, and the c-axis of MoS2 platelets were inclined to the substrate at an angle of -30° to 30°. The hardness of the film ranged from 5.9 to 7.2 GPa depending on the bilayer period. The tribological behavior of the films was performed under vacuum, and the friction coefficient were typically below 0.25. Furthermore, the nanoscale multilayer film with a bilayer period of 20 nm exhibits much better mechanical and tribological properties than pure MoS2. The result indicates that the nanoscale multilayer is a design methodology for developing high basal plane oriented and vacuum solid lubricating MoS2 based materials.

  13. Film/NotFilm

    OpenAIRE

    Willems, Gertjan

    2016-01-01

    Although Samuel Beckett (1906-1989) showed a genuine interest in audio-visual media in his fascinating and innovative radio plays and television works, and in 1936 even wrote a letter to Sergei Eisenstein to be accepted to the famous Soviet film school VGIK, the 22-minute Film (1965) was his only venture into cinema. Beckett conceived the film, wrote the screenplay, supervised the production and, as one of the film’s crew members recalled and as the director Alan Schneider himself acknowledge...

  14. Manipulating lipid bilayer material properties using biologically active amphipathic molecules

    Science.gov (United States)

    Ashrafuzzaman, Md; Lampson, M. A.; Greathouse, D. V.; Koeppe, R. E., II; Andersen, O. S.

    2006-07-01

    Lipid bilayers are elastic bodies with properties that can be manipulated/controlled by the adsorption of amphipathic molecules. The resulting changes in bilayer elasticity have been shown to regulate integral membrane protein function. To further understand the amphiphile-induced modulation of bilayer material properties (thickness, intrinsic monolayer curvature and elastic moduli), we examined how an enantiomeric pair of viral anti-fusion peptides (AFPs)—Z-Gly-D-Phe and Z-Gly-Phe, where Z denotes a benzyloxycarbonyl group, as well as Z-Phe-Tyr and Z-D-Phe-Phe-Gly—alters the function of enantiomeric pairs of gramicidin channels of different lengths in planar bilayers. For both short and long channels, the channel lifetimes and appearance frequencies increase as linear functions of the aqueous AFP concentration, with no apparent effect on the single-channel conductance. These changes in channel function do not depend on the chirality of the channels or the AFPs. At pH 7.0, the relative changes in channel lifetimes do not vary when the channel length is varied, indicating that these compounds exert their effects primarily by causing a positive-going change in the intrinsic monolayer curvature. At pH 4.0, the AFPs are more potent than at pH 7.0 and have greater effects on the shorter channels, indicating that these compounds now change the bilayer elastic moduli. When AFPs of different anti-fusion potencies are compared, the rank order of the anti-fusion activity and the channel-modifying activity is similar, but the relative changes in anti-fusion potency are larger than the changes in channel-modifying activity. We conclude that gramicidin channels are useful as molecular force transducers to probe the influence of small amphiphiles upon lipid bilayer material properties.

  15. The mechanism of detergent solubilization of lipid bilayers.

    Science.gov (United States)

    Lichtenberg, Dov; Ahyayauch, Hasna; Goñi, Félix M

    2013-07-16

    Multiple data are available on the self-assembly of mixtures of bilayer-forming amphiphiles, particularly phospholipids and micelle-forming amphiphiles, commonly denoted detergents. The structure of such mixed assemblies has been thoroughly investigated, described in phase diagrams, and theoretically rationalized in terms of the balance between the large spontaneous curvature of the curvophilic detergent and the curvophobic phospholipids. In this critical review, we discuss the mechanism of this process and try to explain the actual mechanism involved in solubilization. Interestingly, membrane solubilization by some detergents is relatively slow and the common attribute of these detergents is that their trans-bilayer movement, commonly denoted flip-flop, is very slow. Only detergents that can flip into the inner monolayer cause relatively rapid solubilization of detergent-saturated bilayers. This occurs via the following sequence of events: 1), relatively rapid penetration of detergent monomers into the outer monolayer; 2), trans-membrane equilibration of detergent monomers between the two monolayers; 3), saturation of the bilayer by detergents and consequent permeabilization of the membrane; and 4), transition of the whole bilayer to thread-like mixed micelles. When the detergent cannot flip to the inner monolayer, the outer monolayer becomes unstable due to mass imbalance between the monolayers and inclusion of the curvophilic detergent molecules in a flat surface. Consequently, the outer monolayer forms mixed micellar structures within the outer monolayer. Shedding of these micelles into the aqueous solution results in partial solubilization. The consequent leakage of detergent into the liposome results in trans-membrane equilibration of detergent and subsequent micellization through the rapid bilayer-saturation mechanism. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. Preparation, properties and applications of wheat gluten edible films

    Directory of Open Access Journals (Sweden)

    P. TANADA-PALMU

    2008-12-01

    Full Text Available Edible films from wheat gluten were prepared with various amounts of glycerol as a plasticizer. Water vapor permeability, oxygen permeability, tensile strength and percentage elongation at break at different water activities ( aw were measured. Films with low amounts of glycerol had lower water vapor and oxygen permeabilities, higher tensile strength and lower elongation at break. Wheat gluten coatings reduced weight loss during two weeks of storage for cherry tomatoes and sharon fruits compared to uncoated controls. A bilayer film of wheat gluten and beeswax significantly lowered weight loss from coated cheese cubes compared to single layer coating of wheat gluten.;

  17. Study of the influence of semiconductor material parameters on acoustic wave propagation modes in GaSb/AlSb bi-layered structures by Legendre polynomial method

    Science.gov (United States)

    Othmani, Cherif; Takali, Farid; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi

    2016-09-01

    The propagation of Rayleigh-Lamb waves in bi-layered structures is studied. For this purpose, an extension of the Legendre polynomial (LP) method is proposed to formulate the acoustic wave equation in the bi-layered structures induced by thin film Gallium Antimonide (GaSb) and with Aluminum Antimonide (AlSb) substrate in moderate thickness. Acoustic modes propagating along a bi-layer plate are shown to be quite different than classical Lamb modes, contrary to most of the multilayered structures. The validation of the LP method is illustrated by a comparison between the associated numerical results and those obtained using the ordinary differential equation (ODE) method. The convergency of the LP method is discussed through a numerical example. Moreover, the influences of thin film GaSb parameters on the characteristics Rayleigh-Lamb waves propagation has been studied in detail. Finally, the advantages of the Legendre polynomial (LP) method to analyze the multilayered structures are described. All the developments performed in this work were implemented in Matlab software.

  18. Study of the influence of semiconductor material parameters on acoustic wave propagation modes in GaSb/AlSb bi-layered structures by Legendre polynomial method

    Energy Technology Data Exchange (ETDEWEB)

    Othmani, Cherif, E-mail: othmanicheriffss@gmail.com; Takali, Farid; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi

    2016-09-01

    The propagation of Rayleigh–Lamb waves in bi-layered structures is studied. For this purpose, an extension of the Legendre polynomial (LP) method is proposed to formulate the acoustic wave equation in the bi-layered structures induced by thin film Gallium Antimonide (GaSb) and with Aluminum Antimonide (AlSb) substrate in moderate thickness. Acoustic modes propagating along a bi-layer plate are shown to be quite different than classical Lamb modes, contrary to most of the multilayered structures. The validation of the LP method is illustrated by a comparison between the associated numerical results and those obtained using the ordinary differential equation (ODE) method. The convergency of the LP method is discussed through a numerical example. Moreover, the influences of thin film GaSb parameters on the characteristics Rayleigh–Lamb waves propagation has been studied in detail. Finally, the advantages of the Legendre polynomial (LP) method to analyze the multilayered structures are described. All the developments performed in this work were implemented in Matlab software.

  19. Bias induced modulation of electrical and thermal conductivity and heat capacity of BN and BN/graphene bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Chegel, Raad, E-mail: Raad.chegel@gmail.com

    2017-04-15

    By using the tight binding approximation and Green function method, the electronic structure, density of state, electrical conductivity, heat capacity of BN and BN/graphene bilayers are investigated. The AA-, AB{sub 1}- and AB{sub 2}- BN/graphene bilayers have small gap unlike to BN bilayers which are wide band gap semiconductors. Unlike to BN bilayer, the energy gap of graphene/BN bilayers increases with external field. The magnitude of the change in the band gap of BN bilayers is much higher than the graphene/BN bilayers. Near absolute zero, the σ(T) is zero for BN bilayers and it increases with temperature until reaches maximum value then decreases. The BN/graphene bilayers have larger electrical conductivity larger than BN bilayers. For both bilayers, the specific heat capacity has a Schottky anomaly.

  20. Magnetic properties of a doped graphene-like bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Guo, An-Bang [School of Science, Shenyang University of Technology, Shenyang 110870 (China); Jiang, Wei, E-mail: weijiang.sut.edu@gmail.com [School of Science, Shenyang University of Technology, Shenyang 110870 (China); Zhang, Na [Shenyang Normal University, Shenyang 110034 (China)

    2017-05-15

    A doped graphene-like bilayer is described using a four-sublattice Heisenberg model both ferromagnetic and antiferrimagnetic couplings. The magnetic properties of the bilayer system are studied using the Heisenberg model, retarded Green's function and the linear spin-wave approximation. The spin-wave spectra, energy gap, and the magnetization and quantum fluctuation of the system at the ground state are calculated with various intra- and interlayer couplings. The results indicate that the effect of antiferromagnetic exchange coupling on the magnetic properties of the system is significant. Magnetizations at low temperature show intersection points due to the quantum effects.

  1. Proposed parametric cooling of bilayer cuprate superconductors by terahertz excitation.

    Science.gov (United States)

    Denny, S J; Clark, S R; Laplace, Y; Cavalleri, A; Jaksch, D

    2015-04-03

    We propose and analyze a scheme for parametrically cooling bilayer cuprates based on the selective driving of a c-axis vibrational mode. The scheme exploits the vibration as a transducer making the Josephson plasma frequencies time dependent. We show how modulation at the difference frequency between the intrabilayer and interbilayer plasmon substantially suppresses interbilayer phase fluctuations, responsible for switching c-axis transport from a superconducting to a resistive state. Our calculations indicate that this may provide a viable mechanism for stabilizing nonequilibrium superconductivity even above Tc, provided a finite pair density survives between the bilayers out of equilibrium.

  2. Electron-electron interactions in bilayer graphene quantum dots

    Science.gov (United States)

    Zarenia, M.; Partoens, B.; Chakraborty, T.; Peeters, F. M.

    2013-12-01

    A parabolic quantum dot (QD) as realized by biasing nanostructured gates on bilayer graphene is investigated in the presence of electron-electron interaction. The energy spectrum and the phase diagram reveal unexpected transitions as a function of a magnetic field. For example, in contrast to semiconductor QDs, we find a valley transition rather than only the usual singlet-triplet transition in the ground state of the interacting system. The origin of these features can be traced to the valley degree of freedom in bilayer graphene. These transitions have important consequences for cyclotron resonance experiments.

  3. Prediction of superconductivity in Li-intercalated bilayer phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Huang, G. Q. [Department of Physics, Nanjing Normal University, Nanjing 210023 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Xing, Z. W., E-mail: zwxing@nju.edu.cn [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Xing, D. Y. [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2015-03-16

    It is shown that bilayer phosphorene can be transformed from a direct-gap semiconductor to a BCS superconductor by intercalating Li atoms. For the Li-intercalated bilayer phosphorene, we find that the electron occupation of Li-derived band is small and superconductivity is intrinsic. With increasing the intercalation of Li atoms, both increased metallicity and strong electron-phonon coupling are favorable for the enhancement of superconductivity. The obtained electron-phonon coupling λ can be larger than 1 and the superconducting temperature T{sub c} can be increased up to 16.5 K, suggesting that phosphorene may be a good candidate for a nanoscale superconductor.

  4. Chronopotentiometric studies of phosphatidylcholine bilayers modified by ergosterol.

    Science.gov (United States)

    Naumowicz, Monika; Petelska, Aneta Dorota; Figaszewski, Zbigniew Artur

    2011-01-01

    We have monitored the effect of ergosterol on electrical capacitance and electrical resistance of the phosphatidylcholine bilayer membranes using chronopotentiometry method. The chronopotentiometric characteristic of the bilayers depends on constant-current flow through the membranes. For low current values, no electroporation takes place and the membrane voltage rises exponentially to a constant value described by the Ohm's law. Based on these kinds of chronopotentiometric curves, a method of the membrane capacitance and the membrane resistance calculations is presented. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Hydrophobicity, thermal and micro-structural properties of whey protein concentrate-pullulan-beeswax films.

    Science.gov (United States)

    Jafari, Seid Mahdi; Khanzadi, Mehrdad; Mirzaei, Habibollah; Dehnad, Danial; Chegini, Faramarz Khodaian; Maghsoudlou, Yayha

    2015-09-01

    In this research, effects of beeswax (BW) on functional properties of whey protein concentrates (WPC):pullulan (PUL) films were investigated. For this purpose, 0, 10, 20 and 30w/w(glycerol)% BW rates and 30:70, 50:50 and 70:30w/w% WPC:PUL ratios were applied. Films containing 70% WPC:30% PUL (WPC70) and 30% BW (BW30) justified the highest contact angle (92.4°) among all films; SEM micrographs indicated that BW could come toward the surface of films during drying stage and resulted in a higher hydrophobic behavior of bilayer films compared with blend films. WPC70 supplied the lowest T(g) values (36-48 °C) among different proportions of WPC-PUL; the highest melting points were just assured in the absence of BW regardless of combination ratio for WPI:PUL. BW30 films deserved lower roughness rates than BW20 (and even BW10) films, indicating more advantageous microstructure and higher hydrogen connections in BW30 films and justifying similar melting points attained for BW30 films to BW20 or 10 ones. Overall, application of WPC70 and BW30 was recommended to obtain optimum combination of final properties for WPC-PUL-BW bilayer films as SEM exhibited flexible and elastic structures of such films. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Liquid immiscibility in model bilayer lipid membranes

    Science.gov (United States)

    Veatch, Sarah L.

    There is growing evidence that cell plasma membranes are laterally organized into "raft" regions in which particular lipids and proteins are concentrated. These domains have sub-micron dimensions and have been implicated in vital cell functions. Similar liquid domains are observed in model bilayer membrane mixtures that mimick cellular lipid compositions. In model membranes, domains can be large (microns) and can readily form in the absence of proteins. This thesis presents studies of liquid immiscibility in model membrane systems using two experimental methods. By fluorescence microscopy, this thesis documents that miscibility transitions occur in a wide variety of ternary lipid mixtures containing high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol. I have constructed detailed miscibility phase diagrams for three separate ternary lipid mixtures (DOPC/DPPC/Chol, DOPC/PSM/Chol, and POPC/PSM/Chol). Phase separation is also observed in membranes of lipids extracted from human erythrocytes. NMR experiments probe lipid order and verify the coexistence of a saturated lipid and cholesterol rich liquid ordered (Lo) phase with a more disordered, unsaturated lipid rich liquid crystalline (Lalpha) phase at low temperatures. These experiments also find multiple thermodynamic transitions and lipid organization on different length-scales. This complexity is revealed because fluorescence microscopy and NMR probe lipid order at different length-scales (>1mum vs. ˜100nm). NMR detects small domains (˜80nm) at temperatures just below the miscibility transition, even though micron-scale domains are observed by fluorescent microscopy. NMR does detect large-scale ("100nm) demixing, but at a lower temperature. In addition, it has long been known that >10nm length-scale structure is present in many lipid mixtures containing cholesterol and at least one additional lipid species, though it is shown here that only a subset of

  7. Thin Films

    Directory of Open Access Journals (Sweden)

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  8. Interfacial charge trapping in extrinsic Y2O3/SiO2 bilayer gate dielectric based MIS devices on Si(100)

    Science.gov (United States)

    Rastogi, A. C.; Sharma, R. N.

    2001-08-01

    Metal-insulator-semiconductor (MIS) structures based on an extrinsic Y2O3 dielectric film on Si show high leakage currents due to roughness-related highly localized fields. Oxygen annealing increases the dielectric constant and strength and reduces leakage currents by transforming Y2O3 (film)/Si(100) into a bilayer Y2O3 (film)/SiO2/Si(100) dielectric structure. Evolution of interfacial SiO2 causes generation of mid-gap interface states at Ev + 0.23 eV and Ev + 0.43 eV, which act as electron traps and are responsible for hysteresis effects in capacitance-voltage (C-V) and current-voltage (I-V) behaviour in the accumulation-inversion modes. The electron trapping reduces the cathodic field and causes lowering of the current and the shift in current to higher fields after successive ramps. The charge trapping effects cause varied and unstable C-V and I-V behaviour of MIS structures based on a Y2O3/SiO2 bilayer gate dielectric. Its origin has been attributed to microstructure and defect state modification at the Y2O3 film-Si interface. This limits its application in high-density dynamic random access memory and ultra-large-scale integration devices.

  9. Perpendicular magnetic anisotropy of CoFeB\\Ta bilayers on ALD HfO2

    Directory of Open Access Journals (Sweden)

    Bart F. Vermeulen

    2017-05-01

    Full Text Available Perpendicular magnetic anisotropy (PMA is an essential condition for CoFe thin films used in magnetic random access memories. Until recently, interfacial PMA was mainly known to occur in materials stacks with MgO\\CoFe(B interfaces or using an adjacent crystalline heavy metal film. Here, PMA is reported in a CoFeB\\Ta bilayer deposited on amorphous high-κ dielectric (relative permittivity κ=20 HfO2, grown by atomic layer deposition (ALD. PMA with interfacial anisotropy energy Ki up to 0.49 mJ/m2 appears after annealing the stacks between 200°C and 350°C, as shown with vibrating sample magnetometry. Transmission electron microscopy shows that the decrease of PMA starting from 350°C coincides with the onset of interdiffusion in the materials. High-κ dielectrics are potential enablers for giant voltage control of magnetic anisotropy (VCMA. The absence of VCMA in these experiments is ascribed to a 0.6 nm thick magnetic dead layer between HfO2 and CoFeB. The results show PMA can be easily obtained on ALD high-κ dielectrics.

  10. Microstructures and the corresponding magnetic properties of half-doped Nd0.5Sr0.5MnO3 films

    NARCIS (Netherlands)

    Prokhorov, V.G.; Hyun, Y.H.; Park, J.S.; Kim, J.B.; Kim, G.H.; Lee, Y.S.; Lee, Y.P.; Svetchnikov, V.L.

    2008-01-01

    The microstructural and magnetic properties of amorphous, nanoclustered, and self-organized bilayer Nd0.5Sr0.5MnO3 films, prepared by rf magnetron sputtering, are investigated. The amorphous film was found to be a typical paramagnet with free motion of the individual Mn spins, and the magnetic

  11. Photoinduced electron transfer of chlorophyll in lipid bilayer system

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Photoinduced electron transfer from chlorophyll-athrough the interface of dipalmitoylphosphatidylcholine (DPPC) headgroup of the lipid bilayers was studied with electron magnetic resonance (EMR). The photoproduced radicals were identified with electron spin resonance (ESR) and radical yields of chlorophyll- ...

  12. Molecular Dynamics Simulations of Hydrophilic Pores in Lipid Bilayers

    NARCIS (Netherlands)

    Leontiadou, Hari; Mark, Alan E.; Marrink, Siewert J.

    Hydrophilic pores are formed in peptide free lipid bilayers under mechanical stress. It has been proposed that the transport of ionic species across such membranes is largely determined by the existence of such meta-stable hydrophilic pores. To study the properties of these structures and understand

  13. Device model investigation of bilayer organic light emitting diodes

    International Nuclear Information System (INIS)

    Crone, B. K.; Davids, P. S.; Campbell, I. H.; Smith, D. L.

    2000-01-01

    Organic materials that have desirable luminescence properties, such as a favorable emission spectrum and high luminescence efficiency, are not necessarily suitable for single layer organic light-emitting diodes (LEDs) because the material may have unequal carrier mobilities or contact limited injection properties. As a result, single layer LEDs made from such organic materials are inefficient. In this article, we present device model calculations of single layer and bilayer organic LED characteristics that demonstrate the improvements in device performance that can occur in bilayer devices. We first consider an organic material where the mobilities of the electrons and holes are significantly different. The role of the bilayer structure in this case is to move the recombination away from the electrode that injects the low mobility carrier. We then consider an organic material with equal electron and hole mobilities but where it is not possible to make a good contact for one carrier type, say electrons. The role of a bilayer structure in this case is to prevent the holes from traversing the device without recombining. In both cases, single layer device limitations can be overcome by employing a two organic layer structure. The results are discussed using the calculated spatial variation of the carrier densities, electric field, and recombination rate density in the structures. (c) 2000 American Institute of Physics

  14. Localisation of BODIPY-labelled phosphatidylcholines in lipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Šachl, Radek; Boldyrev, I.; Johansson, L. B. A.

    2010-01-01

    Roč. 12, č. 23 (2010), s. 6027-6034 ISSN 1463-9076 R&D Projects: GA ČR GAP208/10/1090 Institutional research plan: CEZ:AV0Z40400503 Keywords : phosphatidylcholines * lipid bilayer * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.454, year: 2010

  15. Electronic transport in disordered bilayer and trilayer graphene

    NARCIS (Netherlands)

    Yuan, Shengjun; De Raedt, Hans; Katsnelson, Mikhail I.

    2010-01-01

    We present a detailed numerical study of the electronic transport properties of bilayer and trilayer graphene within a framework of single-electron tight-binding model. Various types of disorder are considered, such as resonant (hydrogen) impurities, vacancies, short-or long-range Gaussian random

  16. Plasmons in metallic monolayer and bilayer transition metal dichalcogenides

    DEFF Research Database (Denmark)

    Andersen, Kirsten; Thygesen, Kristian S.

    2013-01-01

    We study the collective electronic excitations in metallic single-layer and bilayer transition metal dichalcogenides (TMDCs) using time dependent density functional theory in the random phase approximation. For very small momentum transfers (below q≈0.02 Å−1), the plasmon dispersion follows the √q...

  17. Molecular dynamics study on the relaxation properties of bilayered ...

    Indian Academy of Sciences (India)

    2017-08-31

    Aug 31, 2017 ... Abstract. The influence of defects on the relaxation properties of bilayered graphene (BLG) has been studied by molecular dynamics simulation in nanometre sizes. Type and position of defects were taken into account in the calculated model. The results show that great changes begin to occur in the ...

  18. Determinants of sodium and calcium adsorption onto neutral lipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Javanainen, M.; Melcrová, Adéla; Magarkar, Aniket; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Martinez-Seara, Hector

    2017-01-01

    Roč. 46, Suppl 1 (2017), S121 ISSN 0175-7571. [IUPAB congress /19./ and EBSA congress /11./. 16.07.2017-20.07.2017, Edinburgh] Institutional support: RVO:61388963 ; RVO:61388955 Keywords : sodium * calcium * lipid bilayer Subject RIV: BO - Biophysics

  19. Coherent nonlinear electromagnetic response in twisted bilayer and ...

    Indian Academy of Sciences (India)

    Abstract. The phenomenon of Rabi oscillations far from resonance is described in bilayer and few-layer graphene. These oscillations in the population and polarization at the Dirac point in n-layer graphene are seen in the nth harmonic term in the external driving frequency. The underlying reason behind these oscillations is ...

  20. Coherent nonlinear electromagnetic response in twisted bilayer and ...

    Indian Academy of Sciences (India)

    The phenomenon of Rabi oscillations far from resonance is described in bilayer and few-layer graphene. These oscillations in the population and polarization at the Dirac point in -layer graphene are seen in the nth harmonic termin the external driving frequency. The underlying reason behind these oscillations is ...

  1. Twisted Bilayer Graphene. Interlayer configuration and magnetotransport signatures

    Energy Technology Data Exchange (ETDEWEB)

    Rode, Johannes C.; Smirnov, Dmitri; Belke, Christopher; Schmidt, Hennrik; Haug, Rolf J. [Institut fuer Festkoerperphysik, Hannover (Germany)

    2017-11-15

    Twisted Bilayer Graphene may be viewed as very first representative of the now booming class of artificially layered 2D materials. Consisting of two sheets from the same structure and atomic composition, its decisive degree of freedom lies in the rotation between crystallographic axes in the individual graphene monolayers. Geometrical consideration finds angle-dependent Moire patterns as well as commensurate superlattices of opposite sublattice exchange symmetry. Beyond the approach of rigidly interposed lattices, this review takes focus on the evolving topic of lattice corrugation and distortion in response to spatially varying lattice registry. The experimental approach to twisted bilayers requires a basic control over preparation techniques; important methods are summarized and extended on in the case of bilayers folded from monolayer graphene via AFM nanomachining. Central morphological parameters to the twisted bilayer, rotational mismatch and interlayer separation are studied in a broader base of samples. Finally, experimental evidence for a number of theoretically predicted, controversial electronic scenarios are reviewed; magnetotransport signatures are discussed in terms of Fermi velocity, van Hove singularities and Berry phase and assessed with respect to the underlying experimental conditions, thereby referring back to the initially considered variations in relaxed lattice structure. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Semiconductor particle mediated photoelectron transfers in bilayer lipid membranes

    International Nuclear Information System (INIS)

    Fendler, J.H.; Baral, S.

    1989-01-01

    This paper discusses semiconductor particles in situ generated on the cis surface of glyceryl monooleate (GMO) bilayer lipid membranes (BLMs), that have been used to mediate photoelectric effects. The presence of semiconductors on the BLM surface is addressed. The observed photoelectric effects are rationalized and presented

  3. Formation of Cell Membrane Component Domains in Artificial Lipid Bilayer.

    Science.gov (United States)

    Tero, Ryugo; Fukumoto, Kohei; Motegi, Toshinori; Yoshida, Miyu; Niwano, Michio; Hirano-Iwata, Ayumi

    2017-12-20

    The lipid bilayer environment around membrane proteins strongly affects their structure and functions. Here, we aimed to study the fusion of proteoliposomes (PLs) derived from cultured cells with an artificial lipid bilayer membrane and the distribution of the PL components after the fusion. PLs, which were extracted as a crude membrane fraction from Chinese hamster ovary (CHO) cells, formed isolated domains in a supported lipid bilayer (SLB), comprising phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol (Chol), after the fusion. Observation with a fluorescence microscope and an atomic force microscope showed that the membrane fusion occurred selectively at microdomains in the PC + PE + Chol-SLB, and that almost all the components of the PL were retained in the domain. PLs derived from human embryonic kidney 293 (HEK) cells also formed isolated domains in the PC + PE + Chol-SLB, but their fusion kinetics was different from that of the CHO-PLs. We attempted to explain the mechanism of the PL-SLB fusion and the difference between CHO- and HEK-PLs, based on a kinetic model. The domains that contained the whole cell membrane components provided environments similar to that of natural cell membranes, and were thus effective for studying membrane proteins using artificial lipid bilayer membranes.

  4. Modeling Kinetics of Distortion in Porous Bi-layered Structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Frandsen, Henrik Lund; Bjørk, Rasmus

    2013-01-01

    Shape distortions during constrained sintering experiment of bi-layer porous and dense cerium gadolinium oxide (CGO) structures have been modeled. Technologies like solid oxide fuel cells require co-firing thin layers with different green densities, which often exhibit differential shrinkage...

  5. Development and Evaluation of Controlled-Release Bilayer Tablets ...

    African Journals Online (AJOL)

    Purpose: To develop and characterize bilayer tablet formulations of tramadol HCl (TmH) and acetaminophen (AAP) microparticles. Methods: Coacervation via temperature change was the encapsulated method used for the preparation of the microparticles, with ethyl cellulose (EC) of medium viscosity as the polymer for ...

  6. Energy spectrums of bilayer triangular phosphorene quantum dots and antidots

    Directory of Open Access Journals (Sweden)

    Z. T. Jiang

    2017-04-01

    Full Text Available We theoretically investigate the confined states of the bilayer triangular phosphorene dots and antidots by means of the tight-binding approach. The dependence of the energy levels on the size, the type of the boundary edges, and the orientation of the dots and antidots, and the influences of the electric and magnetic fields on the energy levels, are all completely analyzed. It is found that the energy level numbers of the bilayer dots and antidots are determined by the energy levels in two layers. The external electric field can effectively tune the energy levels of the edge states in both layers to move in opposite directions. With the increase of the magnetic field, the magnetic energy levels can approach the Landau levels of the phosphorene monolayer, the phosphorene bilayer, or both, depending on the specific geometry of the monolayer-bilayer hybrid phosphorene quantum dots. This research should be helpful for the overall understanding of the electronic properties of the multilayer hybrid phosphorene nanostructures and designing the corresponding phosphorene devices.

  7. Coherent nonlinear electromagnetic response in twisted bilayer and ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 83; Issue 4. Coherent nonlinear electromagnetic response in twisted bilayer and few-layer graphene ... These oscillations in the population and polarization at the Dirac point in -layer graphene are seen in the nth harmonic termin the external driving frequency.

  8. Self-assembling bilayers of palladiumthiolates in organic media

    Indian Academy of Sciences (India)

    Alkylthiolates of palladium forming a homologous series (butyl to octadecyl) have been prepared and characterized using X-ray diffraction and STM. The thiolates adopt an unusual bilayered lamellar structure, whose thickness is governed by the length of the alkyl chain. These mesophases melt in the temperature range, ...

  9. Molecular dynamics study on the relaxation properties of bilayered ...

    Indian Academy of Sciences (India)

    The influence of defects on the relaxation properties of bilayered graphene (BLG) has been studied by moleculardynamics simulation in nanometre sizes. Type and position of defects were taken into account in the calculated model. Theresults show that great changes begin to occur in the morphology after introducing ...

  10. Electrochemical synthesis and characterization of bilayers of poly(O ...

    African Journals Online (AJOL)

    Using simple electrosynthesis methods a single and bilayer of conducting polymers, polypyrrole and poly(o-aminophenol) with biopolymer lignin hybrid composites were formed on gold electrodes. The specific capacitance of the single polymer-lignin composite value of 400 F/g obtained from galvanostatic ...

  11. Preparation of InSe Thin Films by Thermal Evaporation Method and Their Characterization: Structural, Optical, and Thermoelectrical Properties

    Directory of Open Access Journals (Sweden)

    Sarita Boolchandani

    2018-01-01

    Full Text Available The indium selenium (InSe bilayer thin films of various thickness ratios, InxSe(1-x (x = 0.25, 0.50, 0.75, were deposited on a glass substrate keeping overall the same thickness of 2500 Ǻ using thermal evaporation method under high vacuum atmosphere. Electrical, optical, and structural properties of these bilayer thin films have been compared before and after thermal annealing at different temperatures. The structural and morphological characterization was done using XRD and SEM, respectively. The optical bandgap of these thin films has been calculated by Tauc’s relation that varies within the range of 1.99 to 2.05 eV. A simple low-cost thermoelectrical power measurement setup is designed which can measure the Seebeck coefficient “S” in the vacuum with temperature variation. The setup temperature variation is up to 70°C. This setup contains a Peltier device TEC1-12715 which is kept between two copper plates that act as a reference metal. Also, in the present work, the thermoelectric power of indium selenide (InSe and aluminum selenide (AlSe bilayer thin films prepared and annealed in the same way is calculated. The thermoelectric power has been measured by estimating the Seebeck coefficient for InSe and AlSe bilayer thin films. It was observed that the Seebeck coefficient is negative for InSe and AlSe thin films.

  12. Development of domperidone bilayered matrix type transdermal patches: physicochemical, in vitro and ex vivo characterization

    Directory of Open Access Journals (Sweden)

    S.K Madishetti

    2010-09-01

    Full Text Available "nBackground and the purpose of the study: Domperidone (DOM is a dopamine- receptor (D2 antagonist, which is widely used in the treatment of motion-sickness. The pharmacokinetic parameters make DOM a suitable candidate for transdermal delivery. The purpose of the present investigation was to develop transdermal delivery systems for DOM and to evaluate their physicochemical characteristics, in vitro release an ex vivo permeation through rat abdominal skin and their mechanical properties. "nMethods: Bilayered matrix type transdermal drug delivery systems (TDDS of DOM were prepared by film casting technique using hydroxypropyl methyl cellulose as primary and Eudragit RL 100 as secondary layers. Brij-35 was incorporated as a solubilizer, d-limonene and propylene glycol were employed as permeation enhancer and plasticizer respectively. The prepared TDDS were extensively evaluated for in vitro release, moisture absorption, moisture content, water vapor transmission, ex vivo permeation through rat abdominal skin, mechanical properties and stability studies. The physicochemical interaction between DOM and polymers were investigated by Differential Scanning Calorimetry (DSC and Fourier Transform Infrared Spectroscopy (FTIR. "nResults: All the formulations exhibited satisfactory physicochemical and mechanical characteristics. The optimized formulation F6 showed maximum cumulative percentage of drug release (90.7%, permeation (6806.64 μg in 24 hrs, flux (86.02 μg /hr/cm2 and permeation coefficient of 0.86x10-2 cm/hr. Values of tensile strength (4.34 kg/mm2 and elastic modulus (5.89 kg/cm2 revealed that formulation F6 was strong but not brittle. DSC and FTIR studies showed no evidence of interaction between the drug and polymers. A shelf life of 2 years is predicted for the TDDS. Conclusions: Domperidone bilayered matrix type transdermal therapeutic systems could be prepared with the required flux and suitable mechanical properties.

  13. P3HT-graphene bilayer electrode for Schottky junction photodetectors

    Science.gov (United States)

    Aydın, H.; Kalkan, S. B.; Varlikli, C.; Çelebi, C.

    2018-04-01

    We have investigated the effect of a poly (3-hexylthiophene-2.5-diyl)(P3HT)-graphene bilayer electrode on the photoresponsivity characteristics of Si-based Schottky photodetectors. P3HT, which is known to be an electron donor and absorb light in the visible spectrum, was placed on CVD grown graphene by dip-coating method. The results of the UV-vis and Raman spectroscopy measurements have been evaluated to confirm the optical and electronic modification of graphene by the P3HT thin film. Current-voltage measurements of graphene/Si and P3HT-graphene/Si revealed rectification behavior confirming a Schottky junction formation at the graphene/Si interface. Time-resolved photocurrent spectroscopy measurements showed the devices had excellent durability and a fast response speed. We found that the maximum spectral photoresponsivity of the P3HT-graphene/Si photodetector increased more than three orders of magnitude compared to that of the bare graphene/Si photodetector. The observed increment in the photoresponsivity of the P3HT-graphene/Si samples was attributed to the charge transfer doping from P3HT to graphene within the spectral range between near-ultraviolet and near-infrared. Furthermore, the P3HT-graphene electrode was found to improve the specific detectivity and noise equivalent power of graphene/Si photodetectors. The obtained results showed that the P3HT-graphene bilayer electrodes significantly improved the photoresponsivity characteristics of our samples and thus can be used as a functional component in Si-based optoelectronic device applications.

  14. Transport in bilayer and trilayer graphene: band gap engineering and band structure tuning

    Science.gov (United States)

    Zhu, Jun

    2014-03-01

    Controlling the stacking order of atomically thin 2D materials offers a powerful tool to control their properties. Linearly dispersed bands become hyperbolic in Bernal (AB) stacked bilayer graphene (BLG). Both Bernal (ABA) and rhombohedral (ABC) stacking occur in trilayer graphene (TLG), producing distinct band structures and electronic properties. A symmetry-breaking electric field perpendicular to the sample plane can further modify the band structures of BLG and TLG. In this talk, I will describe our experimental effort in these directions using dual-gated devices. Using thin HfO2 film deposited by ALD as gate dielectric, we are able to apply large displacement fields D > 6 V/nm and observe the opening and saturation of the field-induced band gap Eg in bilayer and ABC-stacked trilayer graphene, where the conduction in the mid gap changes by more than six decades. Its field and temperature dependence highlights the crucial role played by Coulomb disorder in facilitating hopping conduction and suppressing the effect of Eg in the tens of meV regime. In contrast, mid-gap conduction decreases with increasing D much more rapidly in clean h-BN dual-gated devices. Our studies also show the evolution of the band structure in ABA-stacked TLG, in particular the splitting of the Dirac-like bands in large D field and the signatures of two-band transport at high carrier densities. Comparison to theory reveals the need for more sophisticated treatment of electronic screening beyond self-consistent Hartree calculations to accurately predict the band structures of trilayer graphene and graphenic materials in general.

  15. Effect of film area on critical electric potential for O/W emulsion films breakup

    Energy Technology Data Exchange (ETDEWEB)

    Mostowfi, F. [Schlumberger, Edmonton, AB (Canada). DBR Technology Center; Panchev, N. [Champion Technologies Inc., Houston, TX (United States); Masliyah, J.; Czarnecki, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Bhattacharjee, S. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering

    2008-07-01

    This paper reported on a study in which the critical potentials for breakup of lecithin films were measured at 2 different length scales using 2 different experimental setups. The objective of the study was to explain the electric breakup mechanisms of water-in-oil (W/O) emulsion film based on the theory that larger film areas are less stable and vice versa. In both setups, an electric polarization was applied across an oil film formed between 2 separate water phases. Thin liquid films were formed in toluene using lecithin as surfactant. Lecithin molecules form bilayer films with a thickness of 4-6 nm. Critical potential of breakup were measured over a wide range of lecithin concentrations from 0.05 up to 10 wt per cent. The value of critical potentials in both apparatus showed similar trends. The critical potential for the film breakup was found to be low at low surfactant concentrations because of less stable films at low surface coverage. The increase in film stability at intermediate surfactant concentrations could be attributed to higher surface coverage with the surfactant. At high surfactant concentrations greater than 1 wt per cent, the critical potential asymptotes to about 300 mV. The saturation of critical potential could be explained by saturation of the interfaces with lecithin molecules.

  16. Conductive polymer/superconductor bilayer structures

    International Nuclear Information System (INIS)

    McDevitt, J.T.; Haupt, S.G.; Riley, D.R.; Zhao, J.; Grassi, J.; Lo, R.K.; Jones, C.

    1994-01-01

    The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole-coated YBa 2 Cu 3 O 7-∂ microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa 2 Cu 3 O 7-∂ film, the oxidized (conductive) polymer depresses Tc by up to 50K. In a similar fashion, the oxidation state of the polymer is found to modulate reversibly the magnitude of J c , the superconducting critical current. Thus, a new type of molecular switch for controlling superconductivity is demonstrated. Electrochemical, resistance vs. temperature, conact resistance, atomic force microscopy and scanning electron microscopy measurements are utilized to explore the polymer/superconductor interactions

  17. Lipid bilayer disruption by oligomeric α-synuclein depends on bilayer charge and accessibility of the hydrophobic core

    NARCIS (Netherlands)

    van Rooijen, Bart; Claessens, Mireille Maria Anna Elisabeth; Subramaniam, Vinod

    2009-01-01

    Soluble oligomeric aggregates of α-synuclein have been implicated to play a central role in the pathogenesis of Parkinson's disease. Disruption and permeabilization of lipid bilayers by α-synuclein oligomers is postulated as a toxic mechanism, but the molecular details controlling the

  18. Molecular phospholipid films on solid supports

    DEFF Research Database (Denmark)

    Czolkos, Ilja; Jesorka, Aldo; Orwar, Owe

    2011-01-01

    and aided the development of membrane-based applications in, for example, biosensing, self-assembled reaction kinetics and catalysis. Assembly and preparation of lipid films on supporting surfaces is a challenging engineering task with the goal of fabricating mechanically, chemically and thermodynamically...... stable lipid membranes. In this review, the current state of the art of molecularly thin lipid layer fabrication is presented with an emphasis on support materials, film formation mechanisms, characterisation methods, and applications.......Phospholipid membranes are versatile structures for mimicking biological surfaces. Bilayer and monolayer membranes can be formed on solid supports, leading to enhanced stability and accessibility of the biomimetic molecular film. This has facilitated functional studies of membrane proteins...

  19. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    Science.gov (United States)

    Elam, Fiona M.; Starostin, Sergey A.; Meshkova, Anna S.; van der Velden-Schuermans, Bernadette C. A. M.; van de Sanden, Mauritius C. M.; de Vries, Hindrik W.

    2017-06-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense ‘barrier layer’ and comparatively porous ‘buffer layer’ onto a flexible polyethylene 2,6 naphthalate substrate. For both layers, tetraethyl orthosilicate was used as the precursor gas, together with a mixture of nitrogen, oxygen and argon. The bilayer films demonstrated exceptionally low effective water vapour transmission rates in the region of 6.1  ×  10-4 g m-2 d-1 (at 40 °C, 90% relative humidity), thus capable of protecting flexible photovoltaics and thin film transistors from degradation caused by oxygen and water. The presence of the buffer layer within the bilayer architecture was mandatory in order to achieve the excellent encapsulation performance. Atomic force microscopy in addition to solvent permeation measurements, confirmed that the buffer layer prevented the formation of performance-limiting defects in the bilayer thin films, which likely occur as a result of excessive plasma-surface interactions during the deposition process. It emerged that the primary function of the buffer layer was therefore to act as a protective coating for the flexible polymer substrate material.

  20. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.

    2001-01-01

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...

  1. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NARCIS (Netherlands)

    Elam, F. M.; Starostin, S. A.; Meshkova, A. S.; van der Velden, B. C. A. M.; van de Sanden, M. C. M.; de Vries, H. W.

    2017-01-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense ‘barrier layer’ and comparatively porous ‘buffer layer’ onto a flexible polyethylene 2,6

  2. Temperature dependence of magnetic anisotropies in ultra-thin films

    CERN Document Server

    Hucht, A

    1999-01-01

    shown that in contrast to other works the temperature driven spin reorientation transition in the monolayer is discontinuous also in the simulations, whereas in general it is continuous for the bilayer. Consequently the molecular field theory and the Monte Carlo simulations agree qualitatively. Exemplary for thicker films the influence of an external magnetic field is investigated in the bilayer, furthermore the effective anisotropies K sub n (T) of the phenomenological Landau theory are calculated numerically for the microscopic model. Analytic expressions for the dependence of the anisotropies K sub n (T) on the parameters of the model are obtained by the means of perturbation theory, which lead to a deeper understanding of the spin reorientation transition. Accordingly to this the origin for the spin reorientation transition lies in the differing temperature dependence of the dipolar and spin-orbit parts of the K sub n (T). Additionally the magnetization in the surface of the film decreases more rapidly wi...

  3. Fabrication of efficient graphene-doped polymer/fullerene bilayer organic solar cells in air using spin coating followed by ultrasonic vibration post treatment

    Science.gov (United States)

    Zabihi, Fatemeh; Chen, Qianli; Xie, Yu; Eslamian, Morteza

    2016-12-01

    In this work, in an attempt to improve the performance and lifetime of organic solar cells, P3HT photon absorbing polymer was doped with graphene (G) nano-sheets, to make light harvesting G-P3HT composite thin film. The composite this film was then employed as the donor of a bilayer organic solar cell with the structure of glass/ITO/PEDOT:PSS/G-P3HT/C60/Al. The reference P3HT:PCBM bulk heterojunction solar cell was also fabricated for comparison. All solution-processed layers were made by spin coating in humid air (Shanghai, China); C60 and Al were deposited by thermal evaporation. An effective mechanical treatment approach developed by the authors, i.e. the application of forced ultrasonic vibration on the wet spun-on films, was used to improve the dispersion of graphene in G-P3HT composite films to obtain a uniform nanostructure. This mechanical method eliminates tedious and expensive chemical steps, currently performed to engineer the structure of organic solar cells. It is evidenced that the G-P3HT composite thin films, post treated by ultrasonic vibration at the optimum vibration duration, possess superior electrical conductivity, charge carrier mobility and density, uniform surface potential distribution, and lower surface roughness, compared to those of P3HT and G-P3HT thin films made without vibration. The results show significant improvement in the power conversion efficiency (PCE) of vibration-treated G-P3HT/C60 cell (PCE = 5.17%, the highest reported for this structure), substantiating the strong positive effect of using graphene and forced vibration for the fabrication of P3HT active layer in the bilayer cell structure.

  4. Spin-orbit torques in magnetic bilayers

    Science.gov (United States)

    Haney, Paul

    2015-03-01

    Spintronics aims to utilize the coupling between charge transport and magnetic dynamics to develop improved and novel memory and logic devices. Future progress in spintronics may be enabled by exploiting the spin-orbit coupling present at the interface between thin film ferromagnets and heavy metals. In these systems, applying an in-plane electrical current can induce magnetic dynamics in single domain ferromagnets, or can induce rapid motion of domain wall magnetic textures. There are multiple effects responsible for these dynamics. They include spin-orbit torques and a chiral exchange interaction (the Dzyaloshinskii-Moriya interaction) in the ferromagnet. Both effects arise from the combination of ferromagnetism and spin-orbit coupling present at the interface. There is additionally a torque from the spin current flux impinging on the ferromagnet, arising from the spin hall effect in the heavy metal. Using a combination of approaches, from drift-diffusion to Boltzmann transport to first principles methods, we explore the relative contributions to the dynamics from these different effects. We additionally propose that the transverse spin current is locally enhanced over its bulk value in the vicinity of an interface which is oriented normal to the charge current direction.

  5. Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

    2017-08-15

    Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

  6. Neutron diffraction studies of thin film multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Majkrzak, C.F.

    1985-01-01

    The application of neutron diffraction methods to the study of the microscopic chemical and magnetic structures of thin film multilayers is reviewed. Multilayer diffraction phenomena are described in general and in particular for the case in which one of the materials of a bilayer is ferromagnetic and the neutron beam polarized. Recent neutron diffraction measurements performed on some interesting multilayer systems are discussed. 70 refs., 5 figs.

  7. Neutron diffraction studies of thin film multilayer structures

    International Nuclear Information System (INIS)

    Majkrzak, C.F.

    1985-01-01

    The application of neutron diffraction methods to the study of the microscopic chemical and magnetic structures of thin film multilayers is reviewed. Multilayer diffraction phenomena are described in general and in particular for the case in which one of the materials of a bilayer is ferromagnetic and the neutron beam polarized. Recent neutron diffraction measurements performed on some interesting multilayer systems are discussed. 70 refs., 5 figs

  8. A Molecular Dynamics Study of the Structural and Dynamical Properties of Putative Arsenic Substituted Lipid Bilayers

    Directory of Open Access Journals (Sweden)

    Ratna Juwita

    2013-04-01

    Full Text Available Cell membranes are composed mainly of phospholipids which are in turn, composed of five major chemical elements: carbon, hydrogen, nitrogen, oxygen, and phosphorus. Recent studies have suggested the possibility of sustaining life if the phosphorus is substituted by arsenic. Although this issue is still controversial, it is of interest to investigate the properties of arsenated-lipid bilayers to evaluate this possibility. In this study, we simulated arsenated-lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-arsenocholine (POAC, lipid bilayers using all-atom molecular dynamics to understand basic structural and dynamical properties, in particular, the differences from analogous 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, (POPC lipid bilayers. Our simulations showed that POAC lipid bilayers have distinct structural and dynamical properties from those of native POPC lipid bilayers. Relative to POPC lipid bilayers, POAC lipid bilayers have a more compact structure with smaller lateral areas and greater order. The compact structure of POAC lipid bilayers is due to the fact that more inter-lipid salt bridges are formed with arsenate-choline compared to the phosphate-choline of POPC lipid bilayers. These inter-lipid salt bridges bind POAC lipids together and also slow down the head group rotation and lateral diffusion of POAC lipids. Thus, it would be anticipated that POAC and POPC lipid bilayers would have different biological implications.

  9. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of AB and randomly stacked structures. Herein we report a rational approach to produce large-area high quality AB stacked bilayer graphene. We show that the self-limiting effect of graphene growth on Cu foil can be broken by using a high H2/CH4 ratio in a low pressure CVD process to enable the continued growth of bilayer graphene. A high temperature and low pressure nucleation step is found to be critical for the formation of bilayer graphene nuclei with high AB stacking ratio. A rational design of a two-step CVD process is developed for the growth of bilayer graphene with high AB stacking ratio (up to 90 %) and high coverage (up to 99 %). The electrical transport studies demonstrated that devices made of the as-grown bilayer graphene exhibit typical characteristics of AB stacked bilayer graphene with the highest carrier mobility exceeding 4,000 cm2/V·s at room temperature, comparable to that of the exfoliated bilayer graphene. PMID:22906199

  10. Physisorbed Polymer-Tethered Lipid Bilayer with Lipopolymer Gradient

    Directory of Open Access Journals (Sweden)

    Christoph A. Naumann

    2012-11-01

    Full Text Available Physisorbed polymer-tethered lipid bilayers consisting of phospholipids and lipopolymers represent an attractive planar model membrane platform, in which bilayer fluidity and membrane elastic properties can be regulated through lipopolymer molar concentration. Herein we report a method for the fabrication of such a planar model membrane system with a lateral gradient of lipopolymer density. In addition, a procedure is described, which leads to a sharp boundary between regions of low and high lipopolymer molar concentrations. Resulting gradients and sharp boundaries are visualized on the basis of membrane buckling structures at elevated lipopolymer concentrations using epifluorescence microscopy and atomic force microscopy. Furthermore, results from spot photobleaching experiments are presented, which provide insight into the lipid lateral fluidity in these model membrane architectures. The presented experimental data highlight a planar, solid-supported membrane characterized by fascinating length scale-dependent dynamics and elastic properties with remarkable parallels to those observed in cellular membranes.

  11. Bilayer graphene: physics and application outlook in photonics

    Directory of Open Access Journals (Sweden)

    Yan Hugen

    2015-05-01

    Full Text Available Layered materials, such as graphene, transition metal dichacogenides and black phosphorus have attracted lots of attention recently. They are emerging novel materials in electronics and photonics, with tremendous potential in revolutionizing the traditional electronics and photonics industry. Marrying layered material to the nanophotonics is being proved fruitful. With the recent emphasis and development of metasurfaces in nanophotonics, atomically thin materials can find their unique position and strength in this field. In this article, I will focus on one specific two dimensional material: bilayer graphene. Basic physics will be reviewed, such as band-gap opening, electron-phonon interaction, phonon-plasmon interaction and Fano resonances in the optical response. Moreover, I will review the application of bilayer graphene as a sensitive and fast photodetector. An outlook will be given in the final part of the paper.

  12. Elliptical structure of phospholipid bilayer nanodiscs encapsulated by scaffold proteins

    DEFF Research Database (Denmark)

    Skar-Gislinge, Nicholas; Simonsen, Jens Bæk; Mortensen, Kell

    2010-01-01

    neutron scattering in combination with variable-temperature studies of synchrotron small-angle X-ray scattering on nanodiscs in solution, we show that the fundamental nanodisc unit, consisting of a lipid bilayer surrounded by amphiphilic scaffold proteins, possesses intrinsically an elliptical shape......Phospholipid bilayers host and support the function of membrane proteins and may be stabilized in disc-like nanostructures, allowing for unprecedented solution studies of the assembly, structure, and function of membrane proteins (Bayburt et al. Nano Lett. 2002, 2, 853-856). Based on small-angle...... the experimental scattering profile from nanodiscs. The model paves the way for future detailed structural studies of functional membrane proteins encapsulated in nanodiscs....

  13. Effect of PEGylation on Drug Entry into Lipid Bilayer

    DEFF Research Database (Denmark)

    Rissanen, S.; Kumorek, M.; Martinez-Seara, H.

    2014-01-01

    Poly(ethylene glycol) (PEG) is a polymer commonly used for functionalization of drug molecules to increase their bloodstream lifetime, hence efficacy. However, the interactions between the PEGylated drugs and biomembranes are not clearly understood. In this study, we employed atomic-scale molecular...... dynamics (MD) simulations to consider the behavior of two drug molecules functionalized with PEG (tetraphenylporphyrin used in cancer phototherapy and biochanin A belonging to the isoflavone family) in the presence of a lipid bilayer. The commonly held view is that functionalization of a drug molecule...... with a polymer acts as an entropic barrier, inhibiting the penetration of the drug molecule through a cell membrane. Our results indicate that in the bloodstream there is an additional source of electrostatic repulsive interactions between the PEGylated drugs and the lipid bilayer. Both the PEG chain and lipids...

  14. Polyglutamine expansion in huntingtin increases its insertion into lipid bilayers.

    Science.gov (United States)

    Kegel, Kimberly B; Schewkunow, Vitali; Sapp, Ellen; Masso, Nicholas; Wanker, Erich E; DiFiglia, Marian; Goldmann, Wolfgang H

    2009-09-25

    An expanded polyglutamine (Q) tract (>37Q) in huntingtin (htt) causes Huntington disease. Htt associates with membranes and polyglutamine expansion in htt may alter membrane function in Huntington disease through a mechanism that is not known. Here we used differential scanning calorimetry to examine the effects of polyQ expansion in htt on its insertion into lipid bilayers. We prepared synthetic lipid vesicles composed of phosphatidylcholine and phosphatidylethanolamine and tested interactions of htt amino acids 1-89 with 20Q, 32Q or 53Q with the vesicles. GST-htt1-89 with 53Q inserted into synthetic lipid vesicles significantly more than GST-htt1-89 with 20Q or 32Q. We speculate that by inserting more into cell membranes, mutant huntingtin could increase disorder within the lipid bilayer and thereby disturb cellular membrane function.

  15. Mobility gap and quantum transport in a functionalized graphene bilayer

    Science.gov (United States)

    Missaoui, Ahmed; Jemaa Khabthani, Jouda; Jaidane, Nejm-Eddine; Mayou, Didier; Trambly de Laissardière, Guy

    2018-05-01

    In a Bernal graphene bilayer, carbon atoms belong to two inequivalent sublattices A and B, with atoms that are coupled to the other layer by bonds belonging to sublattice A and the other atoms belonging to sublattice B. We analyze the density of states and the conductivity of Bernal graphene bilayers when atoms of sublattice A or B only are randomly functionalized. We find that for a selective functionalization on sublattice B only, a mobility gap of the order of 0.5 eV is formed close to the Dirac energy at concentration of adatoms . In addition, at some other energies conductivity presents anomalous behaviors. We show that these properties are related to the bipartite structure of the graphene layer.

  16. Exchange bias in diluted-antiferromagnet/antiferromagnet bilayers

    International Nuclear Information System (INIS)

    Mao, Zhongquan; Zhan, Xiaozhi; Chen, Xi

    2015-01-01

    The hysteresis-loop properties of a diluted-antiferromagnetic (DAF) layer exchange coupling to an antiferromagnetic (AF) layer are investigated by means of numerical simulations. Remarkable loop shift and coercivity enhancement are observed in such DAF/AF bilayers, while they are absent in the uncoupled DAF single layer. The influences of pinned domains, dilution, cooling field and DAF layer thickness on the loop shift are investigated systematically. The result unambiguously confirms an exchange bias (EB) effect in the DAF/AF bilayers. It also reveals that the EB effect originates from the pinned AF domains within the DAF layer. In contrast to conventional EB systems, frozen uncompensated spins are not found at the interface of the AF pinning layer. (paper)

  17. The OpenPicoAmp: an open-source planar lipid bilayer amplifier for hands-on learning of neuroscience.

    Science.gov (United States)

    Shlyonsky, Vadim; Dupuis, Freddy; Gall, David

    2014-01-01

    Understanding the electrical biophysical properties of the cell membrane can be difficult for neuroscience students as it relies solely on lectures of theoretical models without practical hands on experiments. To address this issue, we developed an open-source lipid bilayer amplifier, the OpenPicoAmp, which is appropriate for use in introductory courses in biophysics or neurosciences at the undergraduate level, dealing with the electrical properties of the cell membrane. The amplifier is designed using the common lithographic printed circuit board fabrication process and off-the-shelf electronic components. In addition, we propose a specific design for experimental chambers allowing the insertion of a commercially available polytetrafluoroethylene film. We provide a complete documentation allowing to build the amplifier and the experimental chamber. The students hand-out giving step-by step instructions to perform a recording is also included. Our experimental setup can be used in basic experiments in which students monitor the bilayer formation by capacitance measurement and record unitary currents produced by ionic channels like gramicidin A dimers. Used in combination with a low-cost data acquisition board this system provides a complete solution for hands-on lessons, therefore improving the effectiveness in teaching basic neurosciences or biophysics.

  18. Reversible tuning of the wettability on a silver mesodendritic surface by the formation and disruption of lipid-like bilayers

    Science.gov (United States)

    Gao, Yuanji; Xia, Bing; Liu, Jie; Ding, Lisheng; Li, Bangjing; Zhou, Yan

    2015-02-01

    This study reported a smart, easy to apply, flexible and green strategy for obtaining a biomimic micro-nanostructures. 1-Mercapto-12-(p-nitrophenoxy) dodecane (MPND) and n-dodecanethiol were used to form low surface energy film on a silver mesodendritic structure coated zinc substrate. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize surface morphology and mesocrystal structures. Noncovalently linked sodium nonanoyloxy benzene sulfonate (NOBS) was used to form "lipid-like bilayers" on the surface, making it possible for the surface to switch its surface wettability reversibly. The water contact angle (CA) on the constructed surface varies from 168 ± 2° (before processed by NOBS) to 55 ± 2° (after processed by NOBS). This phenomenon can be explained by the formation and disruption of "lipid-like bilayers" to affect the wettability of the surface. This work is of great scientific interests and may provide insights into the design of novel functional devices that are relevant to surface wettability, such as microfluidic devices and sensors.

  19. The OpenPicoAmp: an open-source planar lipid bilayer amplifier for hands-on learning of neuroscience.

    Directory of Open Access Journals (Sweden)

    Vadim Shlyonsky

    Full Text Available Understanding the electrical biophysical properties of the cell membrane can be difficult for neuroscience students as it relies solely on lectures of theoretical models without practical hands on experiments. To address this issue, we developed an open-source lipid bilayer amplifier, the OpenPicoAmp, which is appropriate for use in introductory courses in biophysics or neurosciences at the undergraduate level, dealing with the electrical properties of the cell membrane. The amplifier is designed using the common lithographic printed circuit board fabrication process and off-the-shelf electronic components. In addition, we propose a specific design for experimental chambers allowing the insertion of a commercially available polytetrafluoroethylene film. We provide a complete documentation allowing to build the amplifier and the experimental chamber. The students hand-out giving step-by step instructions to perform a recording is also included. Our experimental setup can be used in basic experiments in which students monitor the bilayer formation by capacitance measurement and record unitary currents produced by ionic channels like gramicidin A dimers. Used in combination with a low-cost data acquisition board this system provides a complete solution for hands-on lessons, therefore improving the effectiveness in teaching basic neurosciences or biophysics.

  20. The influence of interface on spin pumping effect in Ni80Fe20 /Tb bilayer

    Directory of Open Access Journals (Sweden)

    Jinjin Yue

    2016-05-01

    Full Text Available Focusing on the interface effect of the Ni80Fe20 (Py/terbium (Tb bilayer, the influence of interface on the magnetization dynamic damping is investigated systematically. Two series of Py (12 nm/Tb (d nm films with and without copper (Cu (1 nm interlayer are deposited on silicon (Si substrates by DC magnetron sputtering at room temperature. From vibrating sample magnetometer (VSM measurements, the saturation magnetization (Ms decreases with increasing Tb thickness in Py/Tb bilayer while the decrease of Ms is suppressed efficiently by inserting a Cu layer with even 1 nm of thickness. From the frequency dependence of ferromagnetic resonance (FMR linewidth, we can obtain the Gilbert damping coefficient (α, α is found to exhibit an extreme enhancement in comparison to the single Py layer and shows an increasing trend with increasing Tb thickness. By inserting the Cu layer, α decreases significantly. From theoretical fitting, the spin diffusion length (λSD and spin mixing conductance (g↑↓ are determined. It shows that the interface structure influences the spin mixing conductance but not the spin diffusion length.

  1. Evolution of the spin hall magnetoresistance in Cr2O3/Pt bilayers close to the Néel temperature

    Science.gov (United States)

    Schlitz, Richard; Kosub, Tobias; Thomas, Andy; Fabretti, Savio; Nielsch, Kornelius; Makarov, Denys; Goennenwein, Sebastian T. B.

    2018-03-01

    We study the evolution of magnetoresistance with temperature in thin film bilayers consisting of platinum and antiferromagnet Cr2O3 with its easy axis out of the plane. We vary the temperature from 20 °C to 60 °C, in the vicinity of the Néel temperature of Cr2O3 of approximately 37 °C. The magnetoresistive response is recorded during rotations of the external magnetic field in three mutually orthogonal planes. A large magnetoresistance having a symmetry consistent with a positive spin Hall magnetoresistance is observed in the paramagnetic phase of Cr2O3, which however vanishes when cooling to below the Néel temperature. Compared to analogous experiments in a Gd3Ga5O12/Pt bilayer, we conclude that a paramagnetic moment in the insulator induced by an applied magnetic field is not sufficient to explain the observed magnetoresistance. We speculate that the type of magnetic moment at the interface qualitatively impacts the spin angular momentum transfer, with the 3d moments of Cr sinking angular momentum much more efficiently as compared to the more localized 4f moments of Gd.

  2. Interactions of monovalent salts with cationic lipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Pokorná, Šárka; Jurkiewicz, Piotr; Cwiklik, Lukasz; Vazdar, Mario; Hof, Martin

    2013-01-01

    Roč. 160, č. 2013 (2013), s. 341-358 ISSN 1359-6640 R&D Projects: GA ČR GBP208/12/G016; GA AV ČR GEMEM/09/E006 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : FLUORESCENCE SOLVENT RELAXATION * MOLECULAR-DYNAMICS SIMULATIONS * PHOSPHOLIPID-BILAYERS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.194, year: 2013

  3. Partition, orientation and mobility of ubiquinones in a lipid bilayer.

    Science.gov (United States)

    Galassi, Vanesa Viviana; Arantes, Guilherme Menegon

    2015-12-01

    Ubiquinone is the universal mobile charge carrier involved in biological electron transfer processes. Its redox properties and biological function depend on the molecular partition and lateral diffusion over biological membranes. However, ubiquinone localization and dynamics within lipid bilayers are long debated and still uncertain. Here we present molecular dynamics simulations of several ubiquinone homologs with variable isoprenoid tail lengths complexed to phosphatidylcholine bilayers. Initially, a new force-field parametrization for ubiquinone is derived from and compared to high level quantum chemical data. Free energy profiles for ubiquinone insertion in the lipid bilayer are obtained with the new force-field. The profiles allow for the determination of the equilibrium location of ubiquinone in the membrane as well as for the validation of the simulation model by direct comparison with experimental partition coefficients. A detailed analysis of structural properties and interactions shows that the ubiquinone polar head group is localized at the water-bilayer interface at the same depth of the lipid glycerol groups and oriented normal to the membrane plane. Both the localization and orientation of ubiquinone head groups do not change significantly when increasing the number of isoprenoid units. The isoprenoid tail is extended and packed with the lipid acyl chains. For ubiquinones with long tails, the terminal isoprenoid units have high flexibility. Calculated ubiquinone diffusion coefficients are similar to that found for the phosphatidylcholine lipid. These results may have further implications for the mechanisms of ubiquinone transport and binding to respiratory and photosynthetic protein complexes. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Formulation and Evaluation of Mucoadhesive Buccal Bilayered Tablets of Salbutamol

    OpenAIRE

    Dr. N.G Raghavendra Rao; Gururaj S. Kulkarni

    2012-01-01

    Salbutamol is a short-acting 2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. The salbutamol buccal mucoadhesive tablets were fabricated with objective of avoiding first pass metabolism and prolonging duration of action. Salbutamol mucoadhesive bilayered tablets were prepared by direct compression method using the bioadhesive polymers such as xanthan gum, sodium alginate and carbopol 937P along with ethyl...

  5. Superluminal plasmons with resonant gain in population inverted bilayer graphene

    KAUST Repository

    Low, Tony

    2017-12-28

    AB-stacked bilayer graphene with a tunable electronic bandgap in excess of the optical phonon energy presents an interesting active medium, and we consider such theoretical possibility in this work. We argue the possibility of a highly resonant optical gain in the vicinity of the asymmetry gap. Associated with this resonant gain are strongly amplified plasmons, plasmons with negative group velocity and superluminal effects, as well as directional leaky modes.

  6. Non stochastic distribution of single channels in planar lipid bilayers.

    Science.gov (United States)

    Krasilnikov, O V; Merzliak, P G; Yuldasheva, L N; Nogueira, R A; Rodrigues, C G

    1995-02-15

    The selectivity of the planar lipid bilayers modified by two channel-forming proteins (alpha-toxin S. aureus and colicin Ia) was examined. It was established that in all cases the value of zero current potential depended on the amount of open ion channels and increased with the number of channels (from one to about 5-7). These facts point out both the interactions among ion channels and their non stochastic distribution on the membrane surface.

  7. Reversal of exchange bias in nanocrystalline antiferromagnetic-ferromagnetic bilayers

    International Nuclear Information System (INIS)

    Prados, C; Pina, E; Hernando, A; Montone, A

    2002-01-01

    The sign of the exchange bias in field cooled nanocrystalline antiferromagnetic-ferromagnetic bilayers (Co-O and Ni-O/permalloy) is reversed at temperatures approaching the antiferromagnetic (AFM) blocking temperature. A similar phenomenon is observed after magnetic training processes at similar temperatures. These effects can be explained assuming that the boundaries of nanocrystalline grains in AFM layers exhibit lower transition temperatures than grain cores

  8. Solution-processable polymer solar cells from a poly(3-hexylthiophene)/[6,6]-phenyl C61-butyric acidmethyl ester concentration graded bilayers

    International Nuclear Information System (INIS)

    Wang, Dong Hwan; Lee, Hang Ken; Park, O Ok; Choi, Dae-Geun; Park, Jong Hyeok

    2009-01-01

    Polymer photovoltaic (PV) device prepared with a vertical phase separation has intensified the research on the effectiveness of the concentration graded active layer. In this paper, a polymer PV device with a poly(3-hexylthiophene)/[6,6]-phenyl C 61 -butyric acidmethyl ester (P3HT/PCBM) bilayers active film with a concentration gradient has been fabricated via solution process. The concentration variation has been confirmed by the Auger spectroscopy. The devices showed an enhanced photocurrent density and power conversion efficiency compared to those of the bulk heterojunction PV prepared under the same fabrication condition.

  9. Finite element analysis of the cyclic indentation of bilayer enamel

    Science.gov (United States)

    Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

    2014-04-01

    Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel.

  10. Droplet interface bilayer characteristics formed over a synthetic porous substrate

    Science.gov (United States)

    Creasy, M. Austin; Leo, Donald J.

    2009-03-01

    Phospholipid molecules are the fundamental building blocks of cell membranes in living organisms. These molecules are amphipathic with two hydrophobic fatty acid chains (tails) linked to a phosphate containing hydrophilic group (head) that can spontaneously form a bilayer lipid membrane (BLM) with a 6-10 nm thickness in water. BLMs have been classified using some porous synthetic substrate for support. Droplet interface bilayers (DIB) have allowed researchers to study BLMs formed without the use of a porous synthetic substrate. The DIBs are formed at the interface of water droplets and a non-polar solvent. The phospholipids will form a monolayer around the water droplets and when two droplets are brought into contact with each other, a single bilayer will form. DIBs have been used to form networks of BLMs that can be used for multiple purposes. The exact size of the BLM between two droplets is inferred from electrical measurements. The two droplets can be connected through a pore in a synthetic substrate of known dimensions that can limit the area of the BLM. This paper will present the results of forming a BLM on a synthetic substrate by using the DIB method of formation.

  11. Cholesterol Bilayer Domains in the Eye Lens Health: A Review.

    Science.gov (United States)

    Widomska, Justyna; Subczynski, Witold K; Mainali, Laxman; Raguz, Marija

    2017-12-01

    The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.

  12. Amphotericin B induced interdigitation of apolipoprotein stabilized nanodisk bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, T; Weers, P M; Sulchek, T; Hoeprich, P D; Ryan, R O

    2006-12-07

    Amphotericin B nanodisks (AMB-ND) are ternary complexes of AMB, phospholipid (PL) and apolipoprotein organized as discrete nanometer scale disk-shaped bilayers. In gel filtration chromatography experiments, empty ND lacking AMB elute as a single population of particles with a molecular weight in the range of 200 kDa. AMB-ND formulated at a 4:1 PL:AMB weight ratio, separated into two peaks. Peak 1 eluted at the position of control ND lacking AMB while the second peak, containing all of the AMB present in the original sample, eluted in the void volume. When ND prepared with increased AMB (1:1 phospholipid:AMB molar ratio) were subjected to gel filtration chromatography, an increased proportion of phospholipid and apolipoprotein were recovered in the void volume with the AMB. Prior to gel filtration the AMB-ND sample could be passed through a 0.22 {micro}m filter without loss of AMB while the voided material was lost. Native gel electrophoresis studies corroborated the gel permeation chromatography data. Far UV circular dichroism analyses revealed that apoA-I associated with AMB-ND denatures at a lower guanidine HCl concentration than apoA-I associated with ND lacking AMB. Atomic force microscopy revealed that AMB induces compression of the ND bilayer thickness consistent with bilayer interdigitation, a phenomenon that is likely related to the ability of AMB to induce pore formation in susceptible membranes.

  13. Thermoelectric Power in Bilayer Graphene Device with Ionic Liquid Gating.

    Science.gov (United States)

    Chien, Yung-Yu; Yuan, Hongtao; Wang, Chang-Ran; Lee, Wei-Li

    2016-02-08

    The quest for materials showing large thermoelectric power has long been one of the important subjects in material science and technology. Such materials have great potential for thermoelectric cooling and also high figure of merit ZT thermoelectric applications. We have fabricated bilayer graphene devices with ionic-liquid gating in order to tune its band gap via application of a perpendicular electric field on a bilayer graphene. By keeping the Fermi level at charge neutral point during the cool-down, we found that the charge puddles effect can be greatly reduced and thus largely improve the transport properties at low T in graphene-based devices using ionic liquid gating. At (Vig, Vbg) = (-1 V, +23 V), a band gap of about 36.6 ± 3 meV forms, and a nearly 40% enhancement of thermoelectric power at T = 120 K is clearly observed. Our works demonstrate the feasibility of band gap tuning in a bilayer graphene using ionic liquid gating. We also remark on the significant influence of the charge puddles effect in ionic-liquid-based devices.

  14. Exciton-polariton condensation in transition metal dichalcogenide bilayer heterostructure

    Science.gov (United States)

    Lee, Ki Hoon; Jeong, Jae-Seung; Min, Hongki; Chung, Suk Bum

    For the bilayer heterostructure system in an optical microcavity, the interplay of the Coulomb interaction and the electron-photon coupling can lead to the emergence of quasiparticles consisting of the spatially indirect exciton and cavity photons known as dipolariton, which can form the Bose-Einstein condensate above a threshold density. Additional physics comes into play when each layer of the bilayer system consists of the transition metal dichalcogenide (TMD) monolayer. The TMD monolayer band structure in the low energy spectrum has two valley components with nontrivial Berry phase, which gives rise to a selection rule in the exciton-polariton coupling, e.g. the exciton from one (the other) valley can couple only to the clockwise (counter-clockwise) polarized photon. We investigate possible condensate phases of exciton-polariton in the bilayer TMD microcavity changing relevant parameters such as detuning, excitation density and interlayer distance. This work was supported in part by the Institute for Basic Science of Korea (IBS) under Grant IBS-R009-Y1 and by the National Research Foundation of Korea (NRF) under the Basic Science Research Program Grant No. 2015R1D1A1A01058071.

  15. A Neutron View of Proteins in Lipid Bilayers

    Science.gov (United States)

    White, Stephen

    2012-02-01

    Despite the growing number of atomic-resolution membrane protein structures, direct structural information about proteins in their native membrane environment is scarce. This problem is particularly relevant in the case of the highly-charged S1-S4 voltage- sensing domains responsible for nerve impulses, where interactions with the lipid bilayer are critical for the function of voltage-activated potassium channels. We have used neutron diffraction, solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations to investigate the structure and hydration of bilayer membranes containing S1-S4 voltage-sensing domains. Our results show that voltage sensors adopt transmembrane orientations, cause a modest reshaping of the surrounding lipid bilayer, and that water molecules intimately interact with the protein within the membrane. These structural findings reveal that voltage sensors have evolved to interact with the lipid membrane while keeping the energetic and structural perturbations to a minimum, and that water penetrates into the membrane to hydrate charged residues and shape the transmembrane electric field.

  16. Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer–leaflet and inter-leaflet coupling

    Science.gov (United States)

    Hill, Reghan J.; Wang, Chih-Ying

    2014-01-01

    A variety of observations—sometimes controversial—have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans–Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans–Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer–leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements—including lipids, integral monotopic and polytopic proteins, and lipid rafts—in supported bilayer membranes. PMID:25002822

  17. Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer-leaflet and inter-leaflet coupling.

    Science.gov (United States)

    Hill, Reghan J; Wang, Chih-Ying

    2014-07-08

    A variety of observations-sometimes controversial-have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans-Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans-Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer-leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements-including lipids, integral monotopic and polytopic proteins, and lipid rafts-in supported bilayer membranes.

  18. Characteristics and anti-proliferative activity of azelaic acid and its derivatives entrapped in bilayer vesicles in cancer cell lines.

    Science.gov (United States)

    Manosroi, Aranya; Panyosak, Atchara; Rojanasakul, Yon; Manosroi, Jiradej

    2007-06-01

    The hydrophilicity and lipophilicity of azelaic acid (AA) were modified to diethyl azelate (DA) which was synthesized by Fisher esterification reaction and identified by IR, MS and (1)H NMR and to azelaic acid-beta-cyclodextrin complex (AACD) which was prepared by inclusion complexation and identified by IR, DSC and XRD respectively. AA, DA and AACD were entrapped in liposomes and niosomes comprising of L-alpha-dipalmitoyl phosphatidylcholine (DPPC)/cholesterol at 7:3 molar ratio and Tween61/cholesterol at 1:1 molar ratio, respectively, using a thin-film hydration method with sonication. The size and morphology of these bilayer vesicles were determined by optical and transmission electron microscopy. The particle size was found to be in the range of 90-190 nm. The entrapment efficiency of AA, DA and AACD in all vesicular formulations was more than 80%, as analyzed by HPLC for AA and AACD, and GC for DA. Anti-proliferative activity of AA and its derivatives (DA and AACD) both entrapped and not entrapped in bilayer vesicles, using MTT assay in three cancer cell lines (HeLa, KB and B(16)F(10)) comparing with vincristine, were investigated. AACD showed the highest potency comparing to AA in HeLa, KB and B(16)F(10) of 1.48, 1.6 and 1.5 times, respectively. AA entrapped in liposomes was about 90 times more potent than the free AA, and about 1.5 times less potent than vincristine. When entrapped in bilayer vesicles, DA and AACD were more effective than AA in killing cancer cells. AACD entrapped in liposomes gave the highest anti-proliferation activity in HeLa cell lines with the IC(50) of 2.3 and 327 times more potent than vincristine and AA, respectively. DA in liposomes demonstrated the IC(50) of 0.03 times less potent than vincristine in KB cell lines, while in B(16)F(10) AACD in niosomes showed the IC(50) of 0.05 times less potent than vincristine. This study has suggested that the modification of AA by derivatization and complexation as well as the entrapment in

  19. Nuclear films

    International Nuclear Information System (INIS)

    Malone, Peter.

    1985-01-01

    This booklet is a resource for the study of feature films that highlight the theme of nuclear war. It provides basic credits and brief indication of the theme, treatment, quality and particular notable aspects; and a series of questions raised by the film. Seventy feature films and thirty documentaries are examined

  20. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  1. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Pair interaction of bilayer-coated nanoscopic particles

    Science.gov (United States)

    Zhang, Qi-Yi

    2009-02-01

    The pair interaction between bilayer membrane-coated nanosized particles has been explored by using the self-consistent field (SCF) theory. The bilayer membranes are composed of amphiphilic polymers. For different system parameters, the pair-interaction free energies are obtained. Particular emphasis is placed on the analysis of a sequence of structural transformations of bilayers on spherical particles, which occur during their approaching processes. For different head fractions of amphiphiles, the asymmetrical morphologies between bilayers on two particles and the inverted micellar intermediates have been found in the membrane fusion pathway. These results can benefit the fabrication of vesicles as encapsulation vectors for drug and gene delivery.

  2. Permeation of halide anions through phospholipid bilayers occurs by the solubility-diffusion mechanism

    Science.gov (United States)

    Paula, S.; Volkov, A. G.; Deamer, D. W.

    1998-01-01

    Two alternative mechanisms are frequently used to describe ionic permeation of lipid bilayers. In the first, ions partition into the hydrophobic phase and then diffuse across (the solubility-diffusion mechanism). The second mechanism assumes that ions traverse the bilayer through transient hydrophilic defects caused by thermal fluctuations (the pore mechanism). The theoretical predictions made by both models were tested for halide anions by measuring the permeability coefficients for chloride, bromide, and iodide as a function of bilayer thickness, ionic radius, and sign of charge. To vary the bilayer thickness systematically, liposomes were prepared from monounsaturated phosphatidylcholines (PC) with chain lengths between 16 and 24 carbon atoms. The fluorescent dye MQAE (N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide) served as an indicator for halide concentration inside the liposomes and was used to follow the kinetics of halide flux across the bilayer membranes. The observed permeability coefficients ranged from 10(-9) to 10(-7) cm/s and increased as the bilayer thickness was reduced. Bromide was found to permeate approximately six times faster than chloride through bilayers of identical thickness, and iodide permeated three to four times faster than bromide. The dependence of the halide permeability coefficients on bilayer thickness and on ionic size were consistent with permeation of hydrated ions by a solubility-diffusion mechanism rather than through transient pores. Halide permeation therefore differs from that of a monovalent cation such as potassium, which has been accounted for by a combination of the two mechanisms depending on bilayer thickness.

  3. Quasi-Freestanding multilayer graphene films on the carbon face of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, D. A.; Hwang, C. G.; Fedorov, A. V.; Lanzara, A.

    2010-06-30

    The electronic band structure of as-grown and doped graphene grown on the carbon face of SiC is studied by high-resolution angle-resolved photoemission spectroscopy, where we observe both rotations between adjacent layers and AB-stacking. The band structure of quasi-freestanding AB-bilayers is directly compared with bilayer graphene grown on the Si-face of SiC to study the impact of the substrate on the electronic properties of epitaxial graphene. Our results show that the C-face films are nearly freestanding from an electronic point of view, due to the rotations between graphene layers.

  4. Ionic strength and composition govern the elasticity of biological membranes. A study of model DMPC bilayers by force- and transmission IR spectroscopy.

    Science.gov (United States)

    Šegota, Suzana; Vojta, Danijela; Pletikapić, Galja; Baranović, Goran

    2015-02-01

    Infrared (IR) spectroscopy was used to quantify the ion mixture effect of seawater (SW), particularly the contribution of Mg(2+) and Ca(2+) as dominant divalent cations, on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-posphocholine (DMPC) bilayers. The changed character of the main transition at 24 °C from sharp to gradual in films and the 1 °C shift of the main transition temperature in dispersions reflect the interactions of lipid headgroups with the ions in SW. Force spectroscopy was used to quantify the nanomechanical hardness of a DMPC supported lipid bilayer (SLB). Considering the electrostatic and ion binding equilibrium contributions while systematically probing the SLB in various salt solutions, we showed that ionic strength had a decisive influence on its nanomechanics. The mechanical hardness of DMPC SLBs in the liquid crystalline phase linearly increases with the increasing fraction of all ion-bound lipids in a series of monovalent salt solutions. It also linearly increases in the gel phase but almost three times faster (the corresponding slopes are 4.9 nN/100 mM and 13.32 nN/100 mM, respectively). We also showed that in the presence of divalent ions (Ca(2+) and Mg(2+)) the bilayer mechanical hardness was unproportionally increased, and that was accompanied with the decrease of Na(+) ion and increase of Cl(-) ion bound lipids. The underlying process is a cooperative and competitive ion binding in both the gel and the liquid crystalline phase. Bilayer hardness thus turned out to be very sensitive to ionic strength as well as to ionic composition of the surrounding medium. In particular, the indicated correlation helped us to emphasize the colligative properties of SW as a naturally occurring complex ion mixture. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Breakdown of antiferromagnet order in polycrystalline NiFe/NiO bilayers probed with acoustic emission

    Science.gov (United States)

    Lebyodkin, M. A.; Lebedkina, T. A.; Shashkov, I. V.; Gornakov, V. S.

    2017-07-01

    Magnetization reversal of polycrystalline NiFe/NiO bilayers was investigated using magneto-optical indicator film imaging and acoustic emission techniques. Sporadic acoustic signals were detected in a constant magnetic field after the magnetization reversal. It is suggested that they are related to elastic waves excited by sharp shocks in the NiO layer with strong magnetostriction. Their probability depends on the history and number of repetitions of the field cycling, thus testifying the thermal-activation nature of the long-time relaxation of an antiferromagnetic order. These results provide evidence of spontaneous thermally activated switching of the antiferromagnetic order in NiO grains during magnetization reversal in ferromagnet/antiferromagnet (FM/AFM) heterostructures. The respective deformation modes are discussed in terms of the thermal fluctuation aftereffect in the Fulcomer and Charap model which predicts that irreversible breakdown of the original spin orientation can take place in some antiferromagnetic grains with disordered anisotropy axes during magnetization reversal of exchange-coupled FM/AFM structures. The spin reorientation in the saturated state may induce abrupt distortion of isolated metastable grains because of the NiO magnetostriction, leading to excitation of shock waves and formation of plate (or Lamb) waves.

  6. Thickness-dependent surface plasmon resonance of ITO nanoparticles for ITO/In-Sn bilayer structure

    Science.gov (United States)

    Wei, Wenzuo; Hong, Ruijin; Jing, Ming; Shao, Wen; Tao, Chunxian; Zhang, Dawei

    2018-01-01

    Tuning the localized surface plasmon resonance (LSPR) in doped semiconductor nanoparticles (NPs), which represents an important characteristic in LSPR sensor applications, still remains a challenge. Here, indium tin oxide/indium tin alloy (ITO/In-Sn) bilayer films were deposited by electron beam evaporation and the properties, such as the LSPR and surface morphology, were investigated by UV–VIS–NIR double beam spectrophotometer and atomic force microscopy (AFM), respectively. By simply engineering the thickness of ITO/In-Sn NPs without any microstructure fabrications, the LSPR wavelength of ITO NPs can be tuned by a large amount from 858 to 1758 nm. AFM images show that the strong LSPR of ITO NPs is closely related to the enhanced coupling between ITO and In-Sn NPs. Blue shifts of ITO LSPR from 1256 to 1104 nm are also observed in the as-annealed samples due to the higher free carrier concentration. Meanwhile, we also demonstrated that the ITO LSPR in ITO/In-Sn NPs structures has good sensitivity to the surrounding media and stability after 30 d exposure in air, enabling its application prospects in many biosensing devices.

  7. Nanobioarchitectures based on chlorophyll photopigment, artificial lipid bilayers and carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Marcela Elisabeta Barbinta-Patrascu

    2014-12-01

    Full Text Available In the last decade, building biohybrid materials has gained considerable interest in the field of nanotechnology. This paper describes an original design for bionanoarchitectures with interesting properties and potential bioapplications. Multilamellar lipid vesicles (obtained by hydration of a dipalmitoyl phosphatidylcholine thin film with and without cholesterol were labelled with a natural photopigment (chlorophyll a, which functioned as a sensor to detect modifications in the artificial lipid bilayers. These biomimetic membranes were used to build non-covalent structures with single-walled carbon nanotubes. Different biophysical methods were employed to characterize these biohybrids such as: UV–vis absorption and emission spectroscopy, zeta potential measurements, AFM and chemiluminescence techniques. The designed, carbon-based biohybrids exhibited good physical stability, good antioxidant and antimicrobial properties, and could be used as biocoating materials. As compared to the cholesterol-free samples, the cholesterol-containing hybrid structures demonstrated better stability (i.e., their zeta potential reached the value of −36.4 mV, more pronounced oxygen radical scavenging ability (affording an antioxidant activity of 73.25% and enhanced biocidal ability, offering inhibition zones of 12.4, 11.3 and 10.2 mm in diameter, against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis, respectively.

  8. Interaction of Different Divalent Metal Ions with Lipid Bilayer: Impact on the Encapsulation of Doxorubicin by Lipid Bilayer and Lipoplex Mediated Deintercalation.

    Science.gov (United States)

    Das, Anupam; Adhikari, Chandan; Chakraborty, Anjan

    2017-03-02

    In this article, we investigate the influence of different metal ions (Ca 2+ , Mg 2+ , and Zn 2+ ) on binding of an anticancer drug doxorubicin (DOX) to DMPC bilayer and lipoplex mediated deintercalation of DOX from DOX-DNA complex. Our study reveals that lipid bilayer in the presence of different metal ions displays much higher binding affinity toward DOX than bare lipid bilayer does. Further, this affinity for a particular metal ion increases linearly with metal ion concentration. The steady state and time-resolved fluorescence studies reveal that binding of DOX with lipid bilayer in the presence of different metal ions varies in the order of Ca 2+ > Mg 2+ > Zn 2+ . The rotational relaxation of DOX in the presence of different metal ions takes place in the same order. We explain these phenomena in the light of alteration of the physical properties brought about by metal ions. Moreover, we find that binding pattern of metal ions with lipid head groups influences the intake of DOX in lipid bilayer. We exploit the binding of DOX with bilayer to study the deintercalation of DOX from DOX-DNA complex. We observe that with increase in metal ion concentration the deintercalation increases. Among all metal ions, Ca 2+ appears to be most effective in deintercalation compared to other metal ions. The time-resolved fluorescence anisotropy and circular dichroism measurements indicate that in the presence of Ca 2+ , lipid bilayer offer strongest interaction with DNA while the same is weakest for Zn 2+ . This explains the highest percentage of deintercalation of DOX from drug-DNA complex in the presence of Ca 2+ . Overall the present study demonstrates a new strategy that binding of drug molecules with lipid bilayer and deintercalation of the same from drug-DNA complex can be tuned by modulation of lipid bilayer with different metal ions and their concentration.

  9. Towards tunable and multifunctional interfaces: Multicomponent amorphous alloys and bilayer stacks

    Science.gov (United States)

    Kast, Matthew G.

    Controlling the electronic structure and requisite charge transfer at and across interfaces is a grand challenge of materials science. Despite decades of research and numerous successes in the fields microelectronics and photovoltaics much work remains to be done. In many applications, whether they be in microelectronics, photovoltaics or display technology there is a demand for multiple functions at a single interface. Historically, existent materials were either discarded as an option due to known properties or tested with some application based figure of merit in mind. Following this, the quality of the material and/or the preparation of the surface/interface to which the material would be deposited was optimized. As the microelectronics and photovoltaics industries have matured, continued progress (faster, lower power transistors and more efficient, cheaper, abundant solar cells) will require new materials (possibly not previously existent) that are fundamentally better for their application than their highly optimized existent counter parts. The manifestation of this has been seen in the microelectronics field with introduction of hafnium silicates to replace silica (which had previously been monumentally successful) as the gate dielectrics for the most advanced transistors. Continued progress in efficient, cheap, abundant photovoltaics will require similar advances. Advances will be needed in the area of new abundant absorbers that can be deposited cheaply which result in materials with high efficiencies. In addition, selective contacts capable of extracting charge from efficient absorbers with low ohmic losses and low recombination rates will be needed. Presented here are two approaches to the multifunctional interface problem, first the use of amorphous alloys that open up the accessible composition space of thin films significantly and second the use of bilayers that loosen the requirements of a single film at an interface.

  10. Interface alloying in multilayer thin films using polarized neutron reflectometry

    International Nuclear Information System (INIS)

    Basu, Saibal

    2013-01-01

    Polarized Neutron Reflectometry (PNR) is an excellent tool to probe magnetic depth profile in multilayer thin film samples. In case of multilayer films with alternating magnetic and non-magnetic layers, PNR can provide magnetic depth profile at the interfaces with better than nanometer resolution. Using PNR and Xray Reflectometry (XRR) together one can obtain chemical composition and magnetic structure, viz. magnetic moment density at interfaces in multilayer films. We have used these two techniques to obtain kinetics of alloy formation at the interfaces and the magnetic nature of the alloy at the interfaces in several important thin films with magnetic/non-magnetic bilayers. These include Ni/Ti, Ni/Al and Si/Ni pairs. Results obtained from these studies will be presented in this talk. (author)

  11. Monolithic growth of partly cured polydimethylsiloxane thin film layers

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2014-01-01

    at different curing times. The monolithic films are investigated by rheology, scanning electron microscope, mechanical testing, dielectric relaxation spectroscopy, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology, mechanical and dielectric properties, as well...... to enable interlayer crosslinking reactions either by application of an adhesion promoter or by ensuring that there are reactive, complementary sites available on the two surfaces. Polydimethylsiloxane (PDMS) is a widely used polymer for DEAPs. In this work, two-layered PDMS films are adhered together...... as thermal stabilities of the bilayer elastomer films are observed to change with the curing time of the monolayers before lamination. The objective of this work is to create adhesion of two layers without destroying the original viscoelastic properties of the PDMS films, and hence enable, for example...

  12. Mixed-chain phosphatidylcholine bilayers: structure and properties

    International Nuclear Information System (INIS)

    Mattai, J.; Sripada, P.K.; Shipley, G.G.

    1987-01-01

    Calorimetric and x-ray diffraction data are reported for two series of saturated mixed-chain phosphatidylcholines (PCs), 18:0/n:0-PC and n:0/18:0-PC, where the sn-1 and sn-2 fatty acyl chains on the glycerol backbone are systematically varied by two methylene groups from 18:0 to 10:0 (n = 18, 16, 14, 12, or 10). Fully hydrated PCs were annealed at -4 0 C and their multilamellar dispersions characterized by differential scanning calorimetry and x-ray diffraction. All mixed-chain PCs form low-temperature crystalline bilayer phases following low-temperature incubation, except 18:0/10:0-PC. The subtransition temperature (T/sub s/) shifts toward the main (chain melting) transition temperature (T/sub m/) as the sn-1 or sn-2 fatty acyl chain is reduced in length. T/sub m/ decreases with acyl chain length for both series of PCs except 18:0/10:0-PC, while for the positional isomers, n:0/18:0-PC and 18:0/n:0-PC, T/sub m/ is higher for the isomer with the longer acyl chain in the sn-2 position of the glycerol backbone. The conversion from the crystalline bilayer L/sub c/phase to the liquid-crystalline L/sub α/ phase with melted hydrocarbon chains occurs through a series of phase changes which are chain length dependent. Molecular models indicate that the bilayer gel phases for the more asymmetric PC series, 18:0/n:0-PC, must undergo progressive interdigitation with chain length reduction to maintain maximum chain-chain interaction. The L/sub β/* phase of 18:0/10:p-PC is the most stable structure for this PC below T/sub m/. The formation and stability of the triple-chain structures can be rationalized from molecular models

  13. The screening of charged impurities in bilayer graphene

    International Nuclear Information System (INIS)

    Zhang Wenjing; Li, Lain-Jong

    2010-01-01

    Positively charged impurities were introduced into a bilayer graphene (BLG) transistor by n-doping with dimethylformamide. Subsequent exposure of the BLG device to moisture resulted in a positive shift of the Dirac point and an increase of hole mobility, suggesting that moisture could reduce the scattering strength of the existing charged impurities. In other words, moisture screened off the 'effective density' of charged impurities. At the early stage of moisture screening the scattering of hole carriers is dominated by long-range Coulomb scatter, but an alternative scattering mechanism should also be taken into consideration when the effective density of impurities is further lowered on moisture exposure.

  14. Phase behavior of pure lipid bilayers with mismatch interactions

    DEFF Research Database (Denmark)

    Zhang, Zhengping; Laradji, Mohamed; Guo, Hong

    1992-01-01

    but could instead be described in terms of short-range fluctuations close to a critical point. We have extended the Pink-Green-Chapman model by including hydrophobic mismatch interactions between the lipid acyl-chain conformational states. We used Monte Carlo techniques to examine the phase behavior...... of the extended model and found that it exhibits first-order phase transitions above a critical value of the mismatch parameter. The results are discussed in relation to previous theoretical work as well as experimental measurements on lipid bilayers....

  15. Perturbative approach to the mode dispersion in charged particle bilayers

    CERN Document Server

    Ballester, D; Tkachenko, I M; Zhang, H

    2003-01-01

    Earlier theoretical and computer studies on the dynamics of strongly coupled charged particle bilayers have revealed the existence of an energy gap (omega(k = 0) not = 0, optical behaviour) for the out-of-phase plasmon. This is in contrast to the correlationless RPA prediction of acoustic (omega approx k) behaviour. We have studied the question whether a classical perturbation calculation for weak coupling shows the onset of the energy gap, and whether there is a minimal coupling threshold for the formation of the gap. A formally exact lowest order expansion technique due to Zhang and Kalman (1992 Phys. Rev. A 45 5935) has been used.

  16. Tailored sequential drug release from bilayered calcium sulfate composites

    International Nuclear Information System (INIS)

    Orellana, Bryan R.; Puleo, David A.

    2014-01-01

    The current standard for treating infected bony defects, such as those caused by periodontal disease, requires multiple time-consuming steps and often multiple procedures to fight the infection and recover lost tissue. Releasing an antibiotic followed by an osteogenic agent from a synthetic bone graft substitute could allow for a streamlined treatment, reducing the need for multiple surgeries and thereby shortening recovery time. Tailorable bilayered calcium sulfate (CS) bone graft substitutes were developed with the ability to sequentially release multiple therapeutic agents. Bilayered composite samples having a shell and core geometry were fabricated with varying amounts (1 or 10 wt.%) of metronidazole-loaded poly(lactic-co-glycolic acid) (PLGA) particles embedded in the shell and simvastatin directly loaded into either the shell, core, or both. Microcomputed tomography showed the overall layered geometry as well as the uniform distribution of PLGA within the shells. Dissolution studies demonstrated that the amount of PLGA particles (i.e., 1 vs. 10 wt.%) had a small but significant effect on the erosion rate (3% vs. 3.4%/d). Mechanical testing determined that introducing a layered geometry had a significant effect on the compressive strength, with an average reduction of 35%, but properties were comparable to those of mandibular trabecular bone. Sustained release of simvastatin directly loaded into CS demonstrated that changing the shell to core volume ratio dictates the duration of drug release from each layer. When loaded together in the shell or in separate layers, sequential release of metronidazole and simvastatin was achieved. By introducing a tunable, layered geometry capable of releasing multiple drugs, CS-based bone graft substitutes could be tailored in order to help streamline the multiple steps needed to regenerate tissue in infected defects. - Highlights: • Bilayered CS composites were fabricated as potential bone graft substitutes. • The shell

  17. Giant exchange bias in MnPd/Co bilayers

    International Nuclear Information System (INIS)

    Nguyen Thanh Nam; Nguyen Phu Thuy; Nguyen Anh Tuan; Nguyen Nguyen Phuoc; Suzuki, Takao

    2007-01-01

    A systematic study of exchange bias in MnPd/Co bilayers has been carried out, where the dependences of exchange bias, unidirectional anisotropy constant and coercivity on the thicknesses of MnPd and Co layers were investigated. A huge unidirectional anisotropy constant, J K =2.5erg/cm 2 was observed, which is in reasonable agreement with the theoretical prediction based on the model by Meiklejohn and Bean. The angular dependences of exchange bias field and coercivity have also been examined showing that both exchange bias and coercivity follow 1/cosα rule

  18. Biaxial flexural strength of bilayered zirconia using various veneering ceramics

    OpenAIRE

    Chantranikul, Natravee; Salimee, Prarom

    2015-01-01

    PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:20...

  19. Tailored sequential drug release from bilayered calcium sulfate composites

    Energy Technology Data Exchange (ETDEWEB)

    Orellana, Bryan R.; Puleo, David A., E-mail: puleo@uky.edu

    2014-10-01

    The current standard for treating infected bony defects, such as those caused by periodontal disease, requires multiple time-consuming steps and often multiple procedures to fight the infection and recover lost tissue. Releasing an antibiotic followed by an osteogenic agent from a synthetic bone graft substitute could allow for a streamlined treatment, reducing the need for multiple surgeries and thereby shortening recovery time. Tailorable bilayered calcium sulfate (CS) bone graft substitutes were developed with the ability to sequentially release multiple therapeutic agents. Bilayered composite samples having a shell and core geometry were fabricated with varying amounts (1 or 10 wt.%) of metronidazole-loaded poly(lactic-co-glycolic acid) (PLGA) particles embedded in the shell and simvastatin directly loaded into either the shell, core, or both. Microcomputed tomography showed the overall layered geometry as well as the uniform distribution of PLGA within the shells. Dissolution studies demonstrated that the amount of PLGA particles (i.e., 1 vs. 10 wt.%) had a small but significant effect on the erosion rate (3% vs. 3.4%/d). Mechanical testing determined that introducing a layered geometry had a significant effect on the compressive strength, with an average reduction of 35%, but properties were comparable to those of mandibular trabecular bone. Sustained release of simvastatin directly loaded into CS demonstrated that changing the shell to core volume ratio dictates the duration of drug release from each layer. When loaded together in the shell or in separate layers, sequential release of metronidazole and simvastatin was achieved. By introducing a tunable, layered geometry capable of releasing multiple drugs, CS-based bone graft substitutes could be tailored in order to help streamline the multiple steps needed to regenerate tissue in infected defects. - Highlights: • Bilayered CS composites were fabricated as potential bone graft substitutes. • The shell

  20. The effects of globotriaosylceramide tail saturation level on bilayer phases

    DEFF Research Database (Denmark)

    Pezeshkian, Weria; Chaban, Vitaly V; Johannes, Ludger

    2015-01-01

    Globotriaosylceramide (Gb3) is a glycosphingolipid present in the plasma membrane that is the natural receptor of the bacterial Shiga toxin. The unsaturation level of Gb3 acyl chains has a drastic impact on lipid bilayer properties and phase behaviour, and on many Gb3-related cellular processes...... of sphingomyelin lipids and (3) At higher Gb3 concentrations, U-Gb3 mixes better with dioleoylphosphatidylcholine than S-Gb3. Our simulations also provide the first molecular level structural model of Gb3 in membranes....

  1. Homogeneity analysis of sculptured thin films deposited in symmetric style through glancing angle deposition technique

    International Nuclear Information System (INIS)

    Wang Bin; Qi Hong-Ji; Sun Wei; He Jun; Zhao Jiao-Ling; Wang Hu; Hou Yong-Qiang

    2014-01-01

    The symmetric deposition technique is often used to improve the uniformity of sculptured thin film (STF). In this paper, optical properties of STF with the columnar angles ±β are analyzed theoretically, based on the characteristic matrix method for extraordinary waves. Then, the transmittances of uniformity monolayer and bilayer STF in symmetrical style are calculated to show the effect of the bilayer structure on the optical properties of STF. The inhomogeneity of STF is involved in analyzing the differences in transmittance and phase retardation between monolayer and bilayer STF deposited in symmetric style. The results show that optical homogeneity of STF can be improved by depositing in symmetric style at the normal incidence, but it is not the same case as the oblique incidence. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Magnetic behavior of La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Ordonez, John E.; Gomez, Maria E.; Lopera, Wilson; Marin, Lorena; Pardo, Jose A.; Morellon, Luis; Algarabel, Pedro; Prieto, Pedro

    2013-03-01

    We have grown ferroelectric BaTiO3(BTO) and ferromagnetic La2/3Ca1/3MnO3 (LCMO) onto (001) SrTiO3 and Nb:SrTiO3 by pulsed laser deposition (PLD) at pure oxygen atmosphere, and a substrate temperature of 820° C, seeking for a multiferroic behavior in this structure. From x-ray diffraction (XRD) we found lattice parameter aBTO=4.068 Å, and aLCMO=3.804 Å, for each individual layer. In the BTO/LCMO bilayer, (002)-Bragg peak for BTO maintain its position whereas (002) LCMO peak shift to lower Bragg angle indicating a strained LCMO film. Magnetization measurements reveal an increase in the Curie temperature from 170 K to 220 K for the bilayer when LCMO (t = 47 nm) is deposited on BTO (t=52 nm) film, while depositing the BTO (50 nm) above LCMO (48 nm) the Curie temperature remains at values close to that obtained for a LCMO single layer (~175 K), deposited under identical growth parameters This work has been supported by Instituto de Nanociencias de Aragón, Zaragoza, Spain, ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' COLCIENCIAS-CENM Contract RC 275-2011 and Research Project COLCIENCIAS-UNIVALLE.

  3. Cholesterol interactions with fluid-phase phospholipids: effect on the lateral organization of the bilayer.

    Science.gov (United States)

    Halling, Katrin K; Ramstedt, Bodil; Nyström, Joel H; Slotte, J Peter; Nyholm, Thomas K M

    2008-10-01

    The lateral organization of lipids and proteins in cell membranes is recognized as an important factor in several cellular processes. Cholesterol is thought to function as a modulator of the lateral segregation of lipids into cholesterol-poor and cholesterol-rich domains. We investigated how the affinity of cholesterol for different phospholipids, as seen in cholesterol partitioning between methyl-beta-cyclodextrin and large unilamellar vesicles, was reflected in the lateral organization of lipids in complex bilayers. We especially wanted to determine how the low-T(m) lipid affected the lateral structure. Partition experiments showed that cholesterol had a higher affinity for N-oleoyl-sphingomyelin (OSM) than for palmitoyl-oleoyl-phosphatidylcholine (POPC) bilayers, but the highest preference was for N-palmitoyl-sphingomyelin (PSM)-containing bilayers. Partial phase diagrams of POPC/PSM/cholesterol and OSM/PSM/cholesterol bilayers at 23 degrees C and 37 degrees C were used to gain insight into the lateral organization of lipids in bilayers. Analysis of phase diagrams revealed that the phospholipid composition of cholesterol-poor and cholesterol-rich domains reflected the affinity that cholesterol exhibited toward bilayers composed of different lipids. Therefore, the determined affinity of cholesterol for different phospholipid bilayers was useful in predicting the cholesterol-induced lateral segregation of lipids in complex bilayers.

  4. Composition Dependence of Water Permeation Across Multicomponent Gel-Phase Bilayers

    NARCIS (Netherlands)

    Hartkamp, R.M.; Moore, Timothy C.; Iacovella, Christopher R.; Thompson, Michael A.; Bulsara, Pallav A.; Moore, David J.; McCabe, Clare

    2018-01-01

    The permeability of multicomponent phospholipid bilayers in the gel phase is investigated via molecular dynamics simulation. The physical role of the different molecules is probed by comparing multiple mixed-component bilayers containing distearylphosphatidylcholine (DSPC) with varying amounts of

  5. Photolithographic Polymerization of Diacetylene-Containing Phospholipid Bilayers Studied by Multimode Atomic Force Microscopy

    NARCIS (Netherlands)

    Morigaki, Kenichi; Schönherr, Holger; Frank, Curtis W.; Knoll, Wolfgang

    2003-01-01

    Photopolymerization of the diacetylene-containing phospholipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (1) in substrate-supported planar lipid bilayers (SPBs) has been studied by using multimode atomic force microscopy (AFM). Monolayers and bilayers of 1 have been transferred onto

  6. Ca2+-induced isotropic motion and phosphatidylcholine flip-flop in phosphatidylcholine-cardiolipin bilayers

    NARCIS (Netherlands)

    Gerritsen, W.J.; Kruijff, B. de; Verkleij, A.J.; Gier, J. de; Deenen, L.L.M. van

    1980-01-01

    Ca2+ induces a structural change in phosphatidylcholine-cardiolipin bilayers, which is visualised by freeze-fracturing as lipidic particles associated with the bilayer and is detected by 31P-NMR as isotropic motion of the phospholipids. In this structure a rapid transbilayer movement of

  7. Phase behavior of supported lipid bilayers: A systematic study by coarse-grained molecular dynamics simulations

    DEFF Research Database (Denmark)

    Poursoroush, Asma; Sperotto, Maria Maddalena; Laradji, Mohamed

    2017-01-01

    Solid-supported lipid bilayers are utilized by experimental scientists as models for biological membranes because of their stability. However, compared to free standing bilayers, their close proximity to the substrate may affect their phase behavior. As this is still poorly understood, and few co...

  8. Asymmetric dipping of bacteriophage M13 coat protein with increasing lipid bilayer thickness

    NARCIS (Netherlands)

    Stopar, D.; Koehorst, R.B.M.; Spruijt, R.B.; Hemminga, M.A.

    2009-01-01

    Knowledge about the vertical movement of a protein with respect to the lipid bilayer plane is important to understand protein functionality in the biological membrane. In this work, the vertical displacement of bacteriophage M13 major coat protein in a lipid bilayer is used as a model system to

  9. Effect of Anion Triiodide on the Main Phase Transition of Fully Hydrated Dipalmitoylphosphatidylcholine Bilayers

    OpenAIRE

    Hobai, S.; Fazakas, Z.

    1998-01-01

    The paper describes the effect of anion I-3 on thermotropic mesomorphism of fully hydrated dipalmitoylphosphatidylcholine bilayers. The biphasic behaviour of melting temperature - I-3 concentration dependence and the increase of DELTA T values with I-3 concentration (DELTA T = melting temperature - freezing temperature) suggest the appearance of interdigitated phase of bilayers induced by I-3 ions.

  10. Camber Evolution and Stress Development of Porous Ceramic Bilayers During Co-Firing

    DEFF Research Database (Denmark)

    Ni, De Wei; Esposito, Vincenzo; Schmidt, Cristine Grings

    2013-01-01

    sintering mismatch stress in co-fired CGO-LSM/CGO bilayer laminates was significantly lower than general sintering stresses expected for free sintering conditions. As a result, no co-firing defects were observed in the bilayer laminates, illustrating an acceptable sintering compatibility of the ceramic...

  11. Lindane Suppresses the Lipid-bilayer Permeability in Main Transition Region

    DEFF Research Database (Denmark)

    Sabra, Mads Christian; Jørgensen, Kent; Mouritsen, Ole G.

    1996-01-01

    %) of lindane. Fluorescence spectroscopy was used to measure the passive permeability of unilamellar DMPC bilayers to Co2+ ions. The data show that lindane seals the bilayer for Co2+ penetration and that this effect increases with increasing lindane concentration. The results are discussed in relation...... to the effects on the permeability of other small molecules, e.g., anesthetics....

  12. Amphiphile regulation of ion channel function by changes in the bilayer spring constant

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Koeppe, R.E.; Andersen, Oluf Sten

    2010-01-01

    effect of amphiphiles, at concentrations often used in biological research, on the bilayer elastic response to a change in the hydrophobic length of an embedded protein. The effects of structurally diverse amphiphiles can be described by changes in a phenomenological bilayer spring constant (H...

  13. Simulation of gel phase formation and melting in lipid bilayers using a coarse grained model

    NARCIS (Netherlands)

    Marrink, SJ; Risselada, J; Mark, AE

    The transformation between a gel and a fluid phase in dipalmitoyl-phosphatidylcholine (DPPC) bilayers has been simulated using a coarse grained (CG) model by cooling bilayer patches composed of up to 8000 lipids. The critical step in the transformation process is the nucleation of a gel cluster

  14. Sign reversal of drag in bilayer systems with in-plane periodic potential modulation

    DEFF Research Database (Denmark)

    Alkauskas, A.; Flensberg, Karsten; Hu, Ben Yu-Kuang

    2002-01-01

    We develop a theory for describing frictional drag in bilayer systems with in-plane periodic potential modulations, and use it to investigate the drag between bilayer systems in which one of the layers is modulated in one direction. At low temperatures, as the density of carriers in the modulated...

  15. Regulation of membrane protein function by lipid bilayer elasticity—a single molecule technology to measure the bilayer properties experienced by an embedded protein

    DEFF Research Database (Denmark)

    Lundbæk, Jens August

    2008-01-01

    -dependent sodium channels, N-type calcium channels and GABAA receptors, it has been shown that membrane protein function in living cells can be regulated by amphiphile induced changes in bilayer elasticity. Using the gramicidin channel as a molecular force transducer, a nanotechnology to measure the elastic......Membrane protein function is generally regulated by the molecular composition of the host lipid bilayer. The underlying mechanisms have long remained enigmatic. Some cases involve specific molecular interactions, but very often lipids and other amphiphiles, which are adsorbed to lipid bilayers......, regulate a number of structurally unrelated proteins in an apparently non-specific manner. It is well known that changes in the physical properties of a lipid bilayer (e.g., thickness or monolayer spontaneous curvature) can affect the function of an embedded protein. However, the role of such changes...

  16. Demens Film

    DEFF Research Database (Denmark)

    Jensen, Anders Møller

    2012-01-01

    Vi vil skabe film til mennesker med demens – ikke film om demens sygdommen eller beretninger om livet og hverdagen med en kronisk lidelse. Filmene skal medvirke til at frembringe en behagelig stemning omkring og hos mennesker med demens, så hverdagen bliver så tryg som mulig. Filmene skal samtidig...... var at afgrænse og prioritere projektet, samt komme med anbefalinger omkring hvad der er vigtigt, i forbindelse med produktion af film målrettet mennesker med demens. Resultat af ekspertgruppen sammenfattes i denne rapport. Projektet gennemføres som et samarbejde mellem Retrospect Film...

  17. Functional barrier in two-layer recycled PP films for food packaging applications

    Science.gov (United States)

    Scarfato, P.; Di Maio, L.; Milana, M. R.; Feliciani, R.; Denaro, M.; Incarnato, L.

    2014-05-01

    A preliminary study on bi-layer virgin/contaminated polypropylene co-extruded films was performed in order to evaluate the possibility to realize an effective functional barrier in PP-based multi-layer systems. In particular, the specific migration in 10% v/v aqueous ethanol of two surrogate contaminants (phenyl-cyclohexane and benzophenone) contained in the contaminated layer across the PP functional barrier was measured at different times and the results were compared with those obtained from a contaminated mono-layer polypropylene film. Moreover, the thermal and mechanical performances of the produced films were investigated.

  18. Regulation of membrane protein function by lipid bilayer elasticity-a single molecule technology to measure the bilayer properties experienced by an embedded protein

    International Nuclear Information System (INIS)

    Lundbaek, Jens August

    2006-01-01

    Membrane protein function is generally regulated by the molecular composition of the host lipid bilayer. The underlying mechanisms have long remained enigmatic. Some cases involve specific molecular interactions, but very often lipids and other amphiphiles, which are adsorbed to lipid bilayers, regulate a number of structurally unrelated proteins in an apparently non-specific manner. It is well known that changes in the physical properties of a lipid bilayer (e.g., thickness or monolayer spontaneous curvature) can affect the function of an embedded protein. However, the role of such changes, in the general regulation of membrane protein function, is unclear. This is to a large extent due to lack of a generally accepted framework in which to understand the many observations. The present review summarizes studies which have demonstrated that the hydrophobic interactions between a membrane protein and the host lipid bilayer provide an energetic coupling, whereby protein function can be regulated by the bilayer elasticity. The feasibility of this 'hydrophobic coupling mechanism' has been demonstrated using the gramicidin channel, a model membrane protein, in planar lipid bilayers. Using voltage-dependent sodium channels, N-type calcium channels and GABA A receptors, it has been shown that membrane protein function in living cells can be regulated by amphiphile induced changes in bilayer elasticity. Using the gramicidin channel as a molecular force transducer, a nanotechnology to measure the elastic properties experienced by an embedded protein has been developed. A theoretical and technological framework, to study the regulation of membrane protein function by lipid bilayer elasticity, has been established

  19. Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations

    Energy Technology Data Exchange (ETDEWEB)

    Nika, Denis L. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States); Cocemasov, Alexandr I. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Balandin, Alexander A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States)

    2014-07-21

    We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T < 15 K, specific heat varies with temperature as T{sup n}, where n = 1 for graphene, n = 1.6 for bilayer graphene, and n = 1.3 for the twisted bilayer graphene. The phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.

  20. Filament networks attached to membranes: cytoskeletal pressure and local bilayer deformation

    Energy Technology Data Exchange (ETDEWEB)

    Auth, Thorsten [Department of Materials and Interfaces, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel); Safran, S A [Department of Materials and Interfaces, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel); Gov, Nir S [Department of Chemical Physics, Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel)

    2007-11-15

    Several cell types, among them red blood cells, have a cortical, two-dimensional (2D) network of filaments sparsely attached to their lipid bilayer. In many mammalian cells, this 2D polymer network is connected to an underlying 3D, more rigid cytoskeleton. In this paper, we consider the pressure exerted by the thermally fluctuating, cortical network of filaments on the bilayer and predict the bilayer deformations that are induced by this pressure. We treat the filaments as flexible polymers and calculate the pressure that a network of such linear chains exerts on the bilayer; we then minimize the bilayer shape in order to predict the resulting local deformations. We compare our predictions with membrane deformations observed in electron micrographs of red blood cells. The polymer pressure along with the resulting membrane deformation can lead to compartmentalization, regulate in-plane diffusion and may influence protein sorting as well as transmit signals to the polymerization of the underlying 3D cytoskeleton.

  1. Filament networks attached to membranes: cytoskeletal pressure and local bilayer deformation

    International Nuclear Information System (INIS)

    Auth, Thorsten; Safran, S A; Gov, Nir S

    2007-01-01

    Several cell types, among them red blood cells, have a cortical, two-dimensional (2D) network of filaments sparsely attached to their lipid bilayer. In many mammalian cells, this 2D polymer network is connected to an underlying 3D, more rigid cytoskeleton. In this paper, we consider the pressure exerted by the thermally fluctuating, cortical network of filaments on the bilayer and predict the bilayer deformations that are induced by this pressure. We treat the filaments as flexible polymers and calculate the pressure that a network of such linear chains exerts on the bilayer; we then minimize the bilayer shape in order to predict the resulting local deformations. We compare our predictions with membrane deformations observed in electron micrographs of red blood cells. The polymer pressure along with the resulting membrane deformation can lead to compartmentalization, regulate in-plane diffusion and may influence protein sorting as well as transmit signals to the polymerization of the underlying 3D cytoskeleton

  2. [Formation of stabile cupola-like lipid bilayer membranes with a mobile plateau Gibbs boundary].

    Science.gov (United States)

    Shevchenko, E V; Smirnova, E Iu; Frolov, A V; Iakovenko, E V; Antonov, V F

    1993-01-01

    Stable bilayer lipid membrane with mobile Platear-Gibbs border have been formed. The predominant condition of the formation is the presence of lipid coverage on the teflon surface near the hole. The formation process includes transformation of the initial planar lipid bilayer into cupola-shaped one by bowing of the lipid bilayer due to hydrostatic pressure, movement of the PGb along the teflon surface. The bilayer area estimated by electric capacitance increases from 0.1 x 10(-8) F to 21 x 10(-8) F. Electric conductance of the lipid bilayer has not changed except for the phase transition and membrane collapse. The electric capacitance of the BLM formed from hydrogenated egg lecithin was changed by cooling between 60 degrees and 40 degrees C with the maximum at about phase transition range. The individual membrane sustains several scannings of the temperature without disruption which is an evidence of the stability of the cupola-shaped membranes.

  3. Application of self-consistent field theory to self-assembled bilayer membranes

    International Nuclear Information System (INIS)

    Zhang Ping-Wen; Shi An-Chang

    2015-01-01

    Bilayer membranes self-assembled from amphiphilic molecules such as lipids, surfactants, and block copolymers are ubiquitous in biological and physiochemical systems. The shape and structure of bilayer membranes depend crucially on their mechanical properties such as surface tension, bending moduli, and line tension. Understanding how the molecular properties of the amphiphiles determine the structure and mechanics of the self-assembled bilayers requires a molecularly detailed theoretical framework. The self-consistent field theory provides such a theoretical framework, which is capable of accurately predicting the mechanical parameters of self-assembled bilayer membranes. In this mini review we summarize the formulation of the self-consistent field theory, as exemplified by a model system composed of flexible amphiphilic chains dissolved in hydrophilic polymeric solvents, and its application to the study of self-assembled bilayer membranes. (topical review)

  4. Structural Dynamics Of The S4 Voltage-Sensor Helix In Lipid Bilayers Lacking Lipid Phosphates

    Science.gov (United States)

    Andersson, Magnus; Freites, J. Alfredo; Tobias, Douglas J.; White, Stephen H.

    2011-01-01

    Voltage-dependent K+ (Kv) channels require lipid phosphates for functioning. The S4 helix, which carries the gating charges in the voltage-sensing domain (VSD), inserts into membranes while being stabilized by a protein-lipid interface in which lipid phosphates play an essential role. To examine the physical basis of the protein-lipid interface in the absence of lipid phosphates, we performed molecular dynamics (MD) simulations of a KvAP S4 variant (S4mut) in bilayers with and without lipid phosphates. We find that in dioleoyltrimethylammoniumpropane (DOTAP) bilayers lacking lipid phosphates, the gating charges are solvated by anionic counterions and, hence, lack the bilayer support provided by phosphate-containing palmitoyloleoylglycerophosphocholine (POPC) bilayers. The result is a water-permeable bilayer with a significantly smaller deformations around the peptide. Together, these results provide an explanation for the non-functionality of VSDs in terms of a destabilizing protein-lipid interface. PMID:21692541

  5. Tunable electric properties of bilayer InSe with different interlayer distances and external electric field

    Science.gov (United States)

    Shang, Jimin; Pan, Longfei; Wang, Xiaoting; Li, Jingbo; Wei, Zhongming

    2018-03-01

    Using density functional theory we explore the band structure of bilayer Indium selenide (InSe), and we find that the van der Waals interaction has significant effects on the electric and optical properties. We then explore the tuning electronic properties by different interlayer distances and by an external vertical electric field. Our results demonstrate that the band gaps of bilayer InSe can be continuously tuned by different interlayer coupling. With decreasing interlayer distances, the tunable band gaps of bilayer decrease linearly, owing to the enhancement of the interlayer interaction. Additionally, the band structure of bilayer InSe under external vertical fields is discussed. The presence of a small external electric field can make a new spatial distribution of electron-hole pairs. A well separation based on the electrons and holes, localized in different layers can be obtained using this easy method. These properties of bilayer InSe indicates potential applications in designing new optoelectronic devices.

  6. Intrinsic magnetism and spontaneous band gap opening in bilayer silicene and germanene.

    Science.gov (United States)

    Wang, Xinquan; Wu, Zhigang

    2017-01-18

    It has been long sought to create magnetism out of simple non-magnetic materials, such as silicon and germanium. Here we show that intrinsic magnetism exists in bilayer silicene and germanene with no need to cut, etch, or dope. Unlike bilayer graphene, strong covalent interlayer bonding formed in bilayer silicene and germanene breaks the original π-bonding network of each layer, leaving the unbonded electrons unpaired and localized to carry magnetic moments. These magnetic moments then couple ferromagnetically within each layer while antiferromagnetically across two layers, giving rise to an infinite magnetic sheet with structural integrity and magnetic homogeneity. Furthermore, this unique magnetic ordering results in fundamental band gaps of 0.55 eV and 0.32 eV for bilayer silicene and germanene, respectively. The integration of intrinsic magnetism and spontaneous band gap opening makes bilayer silicene and germanene attractive for future nanoelectronics as well as spin-based computation and data storage.

  7. Anomalous swelling of multilamellar lipid bilayers in the transition region by renormalization of curvature elasticity

    DEFF Research Database (Denmark)

    Callisen, Thomas Hønger; Mortensen, Kell; Ipsen, John Hjorth

    1994-01-01

    Small-angle neutron scattering is used to determine the temperature dependence of the lamellar repeat distance in an aqueous multilamellar solution of phospholipid bilayers. A thermal anomaly in the swelling behavior is observed at the bilayer phase transition. The anomalous behavior can be suppr......Small-angle neutron scattering is used to determine the temperature dependence of the lamellar repeat distance in an aqueous multilamellar solution of phospholipid bilayers. A thermal anomaly in the swelling behavior is observed at the bilayer phase transition. The anomalous behavior can...... be suppressed by varying the lipid acyl-chain length or by alloying with a molecular stiffening agent. The experimental results are explained in terms of renormalization of the bilayer curvature elasticity and by using a theory of repulsive interlamellar undulation forces....

  8. Morphogenesis of protrusions from confined lipid bilayers mediated by mechanics

    Science.gov (United States)

    Arroyo, Marino; Staykova, Margarita; Rahimi, Mohammad; Stone, Howard A.

    2012-02-01

    Biological membranes adopt a wide range of shapes that structure and give functionality to cells, compartmentalizing the cytosol, forming organelles, or regulating their area. The formation, stabilization, and remodeling of these structures is generally attributed to localized forces or to biochemical processes (insertion of proteins, active compositional regulation). Noting that in the crowded intra and extra-cellular environments membranes are highly constrained, we explore to what extent can mechanics explain the shape of protrusions out of confined membranes. For this purpose, we developed an in-vitro system coupling a lipid bilayer to the strain-controlled deformation of an elastic sheet (Staykova et al, PNAS 108, 2011). We show that upon contracting the elastic support, tubular or spherical protrusions grow out of the adhered membrane, which can be reversibly controlled with strain and osmolarity without resorting to localized forces or chemical alterations of the bilayer. The morphologies produced by our minimal system are ubiquitous in cells, suggesting mechanics may be a simple and generic organizing principle. We can understand most of our observations in terms of a phase diagram accounting for elasticity, adhesion, and the limited amount of area and volume available.

  9. Interlayer thermal conductance within a phosphorene and graphene bilayer.

    Science.gov (United States)

    Hong, Yang; Zhang, Jingchao; Zeng, Xiao Cheng

    2016-11-24

    Monolayer graphene possesses unusual thermal properties, and is often considered as a prototype system for the study of thermal physics of low-dimensional electronic/thermal materials, despite the absence of a direct bandgap. Another two-dimensional (2D) atomic layered material, phosphorene, is a natural p-type semiconductor and it has attracted growing interest in recent years. When a graphene monolayer is overlaid on phosphorene, the hybrid van der Waals (vdW) bilayer becomes a potential candidate for high-performance thermal/electronic applications, owing to the combination of the direct-bandgap properties of phosphorene with the exceptional thermal properties of graphene. In this work, the interlayer thermal conductance at the phosphorene/graphene interface is systematically investigated using classical molecular dynamics (MD) simulation. The transient pump-probe heating method is employed to compute the interfacial thermal resistance (R) of the bilayer. The predicted R value at the phosphorene/graphene interface is 8.41 × 10 -8 K m 2 W -1 at room temperature. Different external and internal conditions, i.e., temperature, contact pressure, vacancy defect, and chemical functionalization, can all effectively reduce R at the interface. Numerical results of R reduction as a function of temperature, interfacial coupling strength, defect ratio, or hydrogen coverage are reported with the most R reduction amounting to 56.5%, 70.4%, 34.8% and 84.5%, respectively.

  10. Correlations, spin dynamics, defects: the highly-frustrated Kagome bilayer

    International Nuclear Information System (INIS)

    Bono, David; Limot, Laurent; Mendels, Philippe; Collin Gaston; Blanchard Nicole

    2005-01-01

    The SrCr 9p Ga 1 -2 -9p O 19 and Ba 2 Sn 2 ZnGa 10-7p Cr 7p O 22 compounds are two highly-frustrated magnets possessing a quasi-two-dimensional Kagome bilayer of spin 3/2 chromium ions with antiferromagnetic interactions. Their magnetic susceptibility was measured by local nuclear magnetic resonance and nonlocal (SQUID) techniques, and their low-temperature spin dynamics by muon spin resonance. Consistent with the theoretical picture drawn for geometrically frustrated systems, the Kagome bilayer is shown here to exhibit: (i) short range spin-spin correlations down to a temperature much lower than the Curie-Weiss temperature, no conventional long-range transition occurring; (ii) a Curie contribution to the susceptibility from paramagnetic defects generated by spin vacancies; (iii) low-temperature spin fluctuations, at least down to 30 mK, which are a trademark of a dynamical ground state. These properties point to a spin-liquid ground state, possibly built on resonating valence bonds with unconfined spinons as the magnetic excitations

  11. Spectral properties of excitons in the bilayer graphene

    Science.gov (United States)

    Apinyan, V.; Kopeć, T. K.

    2018-01-01

    In this paper, we consider the spectral properties of the bilayer graphene with the local excitonic pairing interaction between the electrons and holes. We consider the generalized Hubbard model, which includes both intralayer and interlayer Coulomb interaction parameters. The solution of the excitonic gap parameter is used to calculate the electronic band structure, single-particle spectral functions, the hybridization gap, and the excitonic coherence length in the bilayer graphene. We show that the local interlayer Coulomb interaction is responsible for the semimetal-semiconductor transition in the double layer system, and we calculate the hybridization gap in the band structure above the critical interaction value. The formation of the excitonic band gap is reported as the threshold process and the momentum distribution functions have been calculated numerically. We show that in the weak coupling limit the system is governed by the Bardeen-Cooper-Schrieffer (BCS)-like pairing state. Contrary, in the strong coupling limit the excitonic condensate states appear in the semiconducting phase, by forming the Dirac's pockets in the reciprocal space.

  12. Protein-induced bilayer perturbations: Lipid ordering and hydrophobic coupling

    International Nuclear Information System (INIS)

    Petersen, Frederic N.R.; Laursen, Ib; Bohr, Henrik; Nielsen, Claus Helix

    2009-01-01

    The host lipid bilayer is increasingly being recognized as an important non-specific regulator of membrane protein function. Despite considerable progress the interplay between hydrophobic coupling and lipid ordering is still elusive. We use electron spin resonance (ESR) to study the interaction between the model protein gramicidin and lipid bilayers of varying thickness. The free energy of the interaction is up to -6 kJ/mol; thus not strongly favored over lipid-lipid interactions. Incorporation of gramicidin results in increased order parameters with increased protein concentration and hydrophobic mismatch. Our findings also show that at high protein:lipid ratios the lipids are motionally restricted but not completely immobilized. Both exchange on and off rate values for the lipid ↔ gramicidin interaction are lowest at optimal hydrophobic matching. Hydrophobic mismatch of few A results in up to 10-fold increased exchange rates as compared to the 'optimal' match situation pointing to the regulatory role of hydrophobic coupling in lipid-protein interactions.

  13. Assembly of RNA nanostructures on supported lipid bilayers

    Science.gov (United States)

    Dabkowska, Aleksandra P.; Michanek, Agnes; Jaeger, Luc; Rabe, Michael; Chworos, Arkadiusz; Höök, Fredrik; Nylander, Tommy; Sparr, Emma

    2014-12-01

    The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection fluorescence microscopy (TIRF) experiments. The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. We show that assembly of the 3D structure can be modulated by sequence specific interactions, surface charge and changes in the salt composition and concentration. In addition, the tertiary structure of the RNA polyhedron can be controllably switched from an extended structure to one that is dense and compact. The versatile approach to building up three-dimensional structures of RNA does not require modification of the surface or the RNA molecules, and can be used as a bottom-up means of nanofabrication of functionalized bio-mimicking surfaces.The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of

  14. Electromagnetic coupling of spins and pseudospins in bilayer graphene

    Science.gov (United States)

    Winkler, R.; Zülicke, U.

    2015-03-01

    We present a theoretical study of bilayer-graphene's electronic properties in the presence of electric and magnetic fields. In contrast to known materials, including single-layer graphene, any possible coupling of physical quantities to components of the electric field has a counterpart where the analogous component of the magnetic field couples to exactly the same quantities. For example, a purely electric spin splitting appears as the magneto-electric analogue of the magnetic Zeeman spin splitting. The measurable thermodynamic response induced by magnetic and electric fields is thus completely symmetric. The Pauli magnetization induced by a magnetic field takes exactly the same functional form as the polarization induced by an electric field. Although they seem counterintuitive, our findings are consistent with fundamental principles such as time reversal symmetry. For example, only a magnetic field can give rise to a macroscopic spin polarization, whereas only a perpendicular electric field can induce a macroscopic polarization of the sublattice-related pseudospin in bilayer graphene. These rules enforced by symmetry for the matter-field interactions clarify the nature of spins versus pseudospins. We have obtained numerical values of prefactors for relevant terms. NSF Grant DMR-1310199 and Marsden Fund Contract No. VUW0719.

  15. Optical response of Al/Ti bilayer transition edge sensors

    International Nuclear Information System (INIS)

    Zhang Qing-Ya; Liu Jian-She; Dong Wen-Hui; He Gen-Fang; Li Tie-Fu; Chen Wei; Wang Tian-Shun; Zhou Xing-Xiang

    2014-01-01

    We report the optical response characteristics of Al/Ti bilayer transition edge sensors (TESs), which are mainly comprised of Al/Ti bilayer thermometers and suspended SiN membranes for thermal isolation. The measurement was performed in a 3 He sorption refrigerator and the device's response to optical pulses was investigated using a pulsed laser source. Based on these measurements, we obtained the effective recovery time (τ eff ) of the devices at different biases and discussed the dependence of τ eff on the bias. The device with a 940 μm × 940 μm continuous suspended SiN membrane demonstrated a fast response speed with τ eff = 3.9 μs, which indicates a high temperature sensitivity (α = T/R · dR/dT = 326). The results also showed that the TES exhibits good linearity under optical pulses of variable widths. (interdisciplinary physics and related areas of science and technology)

  16. Into films

    DEFF Research Database (Denmark)

    Tan, Ed S.; Doicaru, Miruna M.; Hakemulder, Frank

    2017-01-01

    Most film viewers know the experience of being deeply absorbed in the story of a popular film. It seems that at such moments they lose awareness of watching a movie. And yet it is highly unlikely that they completely ignore the fact that they watch a narrative and technological construction...

  17. Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films

    Czech Academy of Sciences Publication Activity Database

    Wadley, P.; Edmonds, K. W.; Shahedkhah, M.R.; Campion, R. P.; Gallagher, B. L.; Železný, Jakub; Kuneš, Jan; Novák, Vít; Jungwirth, Tomáš; Saidl, Vít; Němec, P.; Maccherozzi, F.; Dhesi, S.S.

    2017-01-01

    Roč. 7, Sep (2017), 1-6, č. článku 11147. ISSN 2045-2322 R&D Projects: GA MŠk LM2015087; GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : antiferromagnetic spintronics * exchange coupling Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  18. Magnetic Field Dependence of the Critical Current in S-N Bilayer Thin Films

    Science.gov (United States)

    Sadleir, John E.; Lee, Sang-Jun; Smith, Stephen James; Bandler, Simon; Chervenak, James; Kilbourne, Caroline A.; Finkbeiner, Fred M.; Porter, Frederick S.; Kelley, Richard L.; Adams, Joseph S.; hide

    2013-01-01

    Here we investigate the effects a non-uniform applied magnetic field has on superconducting transition-edge sensors (TESs) critical current. This has implications on TES optimization. It has been shown that TESs resistive transition can be altered by magnetic fields. We have observed critical current rectification effects and explained these effects in terms of a magnetic self-field arising from asymmetric current injection into the sensor. Our TES physical model shows that this magnetic self-field can result in significantly degraded or improved TES performance. In order for this magnetically tuned TES strategy to reach its full potential we are investigating the effect a non-uniform applied magnetic field has on the critical current.

  19. ITO/Poly(Aniline/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Obeidi

    2013-01-01

    Full Text Available Described here is fabrication of a pH-sensitive, optically transparent transducer composed of a planar indium-tin oxide (ITO electrode overcoated with a poly(aniline (PANI thin film and a porous sol-gel layer. Adsorption of the PANI film renders the ITO electrode sensitive to pH, whereas the sol-gel spin-coated layer makes the upper surface compatible with fusion of phospholipid vesicles to form a planar supported lipid bilayer (PSLB. The response to changes in the pH of the buffer contacting the sol-gel/PANI/ITO electrode is pseudo-Nernstian with a slope of 52 mV/pH over a pH range of 4–9. Vesicle fusion forms a laterally continuous PSLB on the upper sol-gel surface that is fluid with a lateral lipid diffusion coefficient of 2.2 μm2/s measured by fluorescence recovery after photobleaching. Due to its lateral continuity and lack of defects, the PSLB blocks the pH response of the underlying electrode to changes in the pH of the overlying buffer. This architecture is simpler to fabricate than previously reported ITO electrodes derivatized for PSLB formation and should be useful for optical monitoring of proton transport across supported membranes derivatized with ionophores and ion channels.

  20. Buckling patterns in biaxially pre-stretched bilayer shells: wrinkles, creases, folds and fracture-like ridges.

    Science.gov (United States)

    Al-Rashed, Rashed; López Jiménez, Francisco; Marthelot, Joel; Reis, Pedro M

    2017-11-08

    We introduce a new experimental system to study the effects of pre-stretch on the buckling patterns that emerge from the biaxial compression of elastomeric bilayer shells. Upon fabrication of the samples, releasing the pre-stretch in the substrate through deflation places the outer film in a state of biaxial compression and yields a variety of buckling patterns. We systematically explore the parameter space by varying the pre-stretch of the substrate and the ratio between the stiffness of the substrate and film. The phase diagram of the system exhibits a variety of buckling patterns: from the classic periodic wrinkle to creases, folds, and high aspect ratio ridges. Our system is capable of readily transitioning between these buckling patterns, a first for biaxial systems. We focus on the wrinkle to ridge transition. In the latter, we find that pre-stretch plays an essential role and that the ridge geometry (width, height) remains nearly constant throughout their formation process. For the localized ridged patterns, we find that the propagation of the ridge tip depends strongly on both strain and stiffness ratio, in a way that is akin to hierarchical fracture.

  1. Ammonia gas sensors based on poly (3-hexylthiophene)-molybdenum disulfide film transistors

    International Nuclear Information System (INIS)

    Xie, Tao; Xie, Guangzhong; Su, Yuanjie; Hongfei, Du; Ye, Zongbiao; Jiang, Yadong

    2016-01-01

    In this work, in order to enhance the recovery performance of organic thin film transistors (OTFTs) ammonia (NH 3 ) sensors, poly (3-hexylthiophene) (P3HT) and molybdenum disulfide (MoS 2 ) were combined as sensitive materials. Different sensitive film structures as active layers of OTFTs, i.e., P3HT-MoS 2 composite film, P3HT/MoS 2 bilayer film and MoS 2 /P3HT bilayer film were fabricated by spray technology. OTFT gas sensors based on P3HT-MoS 2 composite film showed a shorter recovery time than others when the ammonia concentration changed from 4 to 20 ppm. Specifically, x-ray diffraction (XRD), Raman and UV-visible absorption were employed to explore the interface properties between P3HT and single-layer MoS 2 . Through the complementary characterization, a mechanism based on charge transfer is proposed to explain the physical originality of these OTFT gas sensors: closer interlayer d-spacing and better π–π stacking of the P3HT chains in composite film have ensured a short recovery time of OTFT gas sensors. Moreover, sensing mechanisms of OTFTs were further studied by comparing the device performance in the presence of nitrogen or dry air as a carrier gas. This work not only strengthens the fundamental understanding of the sensing mechanism, but provides a promising approach to optimizing the OTFT gas sensors. (paper)

  2. Effect of Substrates on the Dynamic Properties of Inkjet-Printed Ag Thin Films

    Directory of Open Access Journals (Sweden)

    Deokman Kim

    2018-01-01

    Full Text Available The dynamic properties of inkjet-printed Ag thin films on flexible substrates were measured using flexural wave propagation. The Ag nanoparticle suspension was inkjet-printed on polyimide (PI, silicon wafer, and glass. The effects of flexible substrates on the dynamic properties of the films were investigated. Beam-shaped Ag-printed substrates were fabricated by pico-second laser pulse cutting. The wave approach was presented to analyze the vibrations of the thin film on the substrates. The Young’s modulus and loss factor of the Ag thin films with the substrates were represented by the combined bending stiffness of the bilayer beam. The vibration response of the base-excited cantilever was measured using an accelerometer and laser Doppler vibrometer (LDV. Vibration transfers were analyzed to obtain dynamic characteristics of the Ag-printed bilayer beam. The substrate affects the reduction of the Ag thin film thickness during the sintering process and surface roughness of the film. The proposed method based on the wave approach allows measurement of the dynamic properties regardless of the ratio of the modulus between the thin film and substrate.

  3. The role of nonlinear substrate elasticity in the wrinkling of thin films.

    Science.gov (United States)

    Hutchinson, John W

    2013-06-28

    The role of substrate nonlinearity in the stability of wrinkling of thin films bonded to compliant substrates is investigated within the initial post-bifurcation range when wrinkling first emerges. A fully nonlinear neo-Hookean bilayer composed of a thin film on a deep substrate is analysed for a wide range of the film-substrate stiffness ratio, from films that are very stiff compared with the substrate to those only slightly stiffer. Substrate pre-stretch prior to film attachment is shown to have a significant effect on the nonlinearity relevant to wrinkling. Two dimensionless parameters are identified that control the stability and mode shape evolution of the bilayer: one specifying arbitrary uniform substrate pre-stretch and the other a stretch-modified modulus ratio. For systems with film stiffness greater than about five times that of the substrate the wrinkling bifurcation is stable, whereas for systems with smaller relative film stiffness bifurcation can be unstable, especially if substrate pre-stretch is not tensile.

  4. Lepromatous leprosy patients produce antibodies that recognise non-bilayer lipid arrangements containing mycolic acids

    Directory of Open Access Journals (Sweden)

    Isabel Baeza

    2012-12-01

    Full Text Available Non-bilayer phospholipid arrangements are three-dimensional structures that form when anionic phospholipids with an intermediate structure of the tubular hexagonal phase II are present in a bilayer of lipids. Antibodies that recognise these arrangements have been described in patients with antiphospholipid syndrome and/or systemic lupus erythematosus and in those with preeclampsia; these antibodies have also been documented in an experimental murine model of lupus, in which they are associated with immunopathology. Here, we demonstrate the presence of antibodies against non-bilayer phospholipid arrangements containing mycolic acids in the sera of lepromatous leprosy (LL patients, but not those of healthy volunteers. The presence of antibodies that recognise these non-bilayer lipid arrangements may contribute to the hypergammaglobulinaemia observed in LL patients. We also found IgM and IgG anti-cardiolipin antibodies in 77% of the patients. This positive correlation between the anti-mycolic-non-bilayer arrangements and anti-cardiolipin antibodies suggests that both types of antibodies are produced by a common mechanism, as was demonstrated in the experimental murine model of lupus, in which there was a correlation between the anti-non-bilayer phospholipid arrangements and anti-cardiolipin antibodies. Antibodies to non-bilayer lipid arrangements may represent a previously unrecognised pathogenic mechanism in LL and the detection of these antibodies may be a tool for the early diagnosis of LL patients.

  5. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  6. The Molecular Structure of a Phosphatidylserine Bilayer Determined by Scattering and Molecular Dynamics Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Jianjun [University of South Florida, Tampa (USF); Cheng, Xiaolin [ORNL; Monticelli, Luca [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France; Heberle, Frederick A [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Tieleman, D. Peter [University of Calgary, ALberta, Canada; Katsaras, John [ORNL

    2014-01-01

    Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.

  7. The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: structure and lubrication performance.

    Science.gov (United States)

    Wang, Min; Zander, Thomas; Liu, Xiaoyan; Liu, Chao; Raj, Akanksha; Wieland, D C Florian; Garamus, Vasil M; Willumeit-Römer, Regine; Claesson, Per Martin; Dėdinaitė, Andra

    2015-05-01

    Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25-52°C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica-liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25°C and 39°C and in the liquid disordered state at 55°C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37°C. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  8. Ultra-high vacuum surface analysis study of rhodopsin incorporation into supported lipid bilayers.

    Science.gov (United States)

    Michel, Roger; Subramaniam, Varuni; McArthur, Sally L; Bondurant, Bruce; D'Ambruoso, Gemma D; Hall, Henry K; Brown, Michael F; Ross, Eric E; Saavedra, S Scott; Castner, David G

    2008-05-06

    Planar supported lipid bilayers that are stable under ambient atmospheric and ultra-high-vacuum conditions were prepared by cross-linking polymerization of bis-sorbylphosphatidylcholine (bis-SorbPC). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to investigate bilayers that were cross-linked using either redox-initiated radical polymerization or ultraviolet photopolymerization. The redox method yields a more structurally intact bilayer; however, the UV method is more compatible with incorporation of transmembrane proteins. UV polymerization was therefore used to prepare cross-linked bilayers with incorporated bovine rhodopsin, a light-activated, G-protein-coupled receptor (GPCR). A previous study (Subramaniam, V.; Alves, I. D.; Salgado, G. F. J.; Lau, P. W.; Wysocki, R. J.; Salamon, Z.; Tollin, G.; Hruby, V. J.; Brown, M. F.; Saavedra, S. S. J. Am. Chem. Soc. 2005, 127, 5320-5321) showed that rhodopsin retains photoactivity after incorporation into UV-polymerized bis-SorbPC, but did not address how the protein is associated with the bilayer. In this study, we show that rhodopsin is retained in supported bilayers of poly(bis-SorbPC) under ultra-high-vacuum conditions, on the basis of the increase in the XPS nitrogen concentration and the presence of characteristic amino acid peaks in the ToF-SIMS data. Angle-resolved XPS data show that the protein is inserted into the bilayer, rather than adsorbed on the bilayer surface. This is the first study to demonstrate the use of ultra-high-vacuum techniques for structural studies of supported proteolipid bilayers.

  9. Demens Film

    DEFF Research Database (Denmark)

    Ridder, Hanne Mette Ochsner

    2012-01-01

    I forbindelse med opstarten af Demens Film projektet har der været nedsat en ekspertgruppe, som er kommet med en række anbefalinger omkring film til mennesker med demens. Anbefalingerne skal bruges i de næste faser af projektet. Deltagerne i ekspertgruppen var sammensat af en bred gruppe...... fagpersoner inde for forskellige fagområder. Læs mere om gruppens anbefalinger og sammensætning af ekspertgruppen i den kort rapport som er offentlig tilgængelig. Læs Ekspertgruppe anbefalingerne til Demens Film projekt....

  10. Magnetic bilayer-skyrmions without skyrmion Hall effect

    Science.gov (United States)

    Zhang, Xichao; Zhou, Yan; Ezawa, Motohiko

    2016-01-01

    Magnetic skyrmions might be used as information carriers in future advanced memories, logic gates and computing devices. However, there exists an obstacle known as the skyrmion Hall effect (SkHE), that is, the skyrmion trajectories bend away from the driving current direction due to the Magnus force. Consequently, the skyrmions in constricted geometries may be destroyed by touching the sample edges. Here we theoretically propose that the SkHE can be suppressed in the antiferromagnetically exchange-coupled bilayer system, since the Magnus forces in the top and bottom layers are exactly cancelled. We show that such a pair of SkHE-free magnetic skyrmions can be nucleated and be driven by the current-induced torque. Our proposal provides a promising means to move magnetic skyrmions in a perfectly straight trajectory in ultra-dense devices with ultra-fast processing speed.

  11. Probing the position of resveratrol in lipid bilayers

    DEFF Research Database (Denmark)

    de Ghellinck, Alexis; Shen, Chen; Fragneto, Giovanna

    2015-01-01

    The effect of the natural antioxidant resveratrol on the structure of solid supported di-palmitoyl-phosphatidyl-choline (DPPC) bilayers in their fluid state was investigated by neutron reflectometry. Results reveal an accumulation of resveratrol (up to 25%, mol/mol) inside the headgroups...... and they exclude its presence in the hydrophobic core. The presence of resveratrol induces an increase of the average thickness and of the interfacial roughness of the headgroup layer. This may be due to a change of the tilt angle of the phosphocholine headgroups residing next to the resveratrol to a more upright...... orientation and leading to a reduction of the projected area per headgroup. This effect is propagated into the hydrophobic core, where the chain packing is modified despite the absence of resveratrol. When interacting with a DPPC/cholesterol membrane, resveratrol has a similar effect on the neighboring PC...

  12. Universal quantum computation with temporal-mode bilayer square lattices

    Science.gov (United States)

    Alexander, Rafael N.; Yokoyama, Shota; Furusawa, Akira; Menicucci, Nicolas C.

    2018-03-01

    We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state.

  13. Theoretical studies of lipid bilayer electroporation using molecular dynamics simulations

    Science.gov (United States)

    Levine, Zachary Alan

    Computer simulations of physical, chemical, and biological systems have improved tremendously over the past five decades. From simple studies of liquid argon in the 1960s to fully atomistic simulations of entire viruses in the past few years, recent advances in high-performance computing have continuously enabled simulations to bridge the gap between scientific theory and experiment. Molecular dynamics simulations in particular have allowed for the direct observation of spatial and temporal events which are at present inaccessible to experiments. For this dissertation I employ all-atom molecular dynamics simulations to study the transient, electric field-induced poration (or electroporation) of phospholipid bilayers at MV/m electric fields. Phospholipid bilayers are the dominant constituents of cell membranes and act as both a barrier and gatekeeper to the cell interior. This makes their structural integrity and susceptibility to external perturbations an important topic for study, especially as the density of electromagnetic radiation in our environment is increasing steadily. The primary goal of this dissertation is to understand the specific physical and biological mechanisms which facilitate electroporation, and to connect our simulated observations to experiments with live cells and to continuum models which seek to describe the underlying biological processes of electroporation. In Chapter 1 I begin with a brief introduction to phospholipids and phospholipid bilayers, followed by an extensive overview of electroporation and atomistic molecular dynamics simulations. The following chapters will then focus on peer-reviewed and published work we performed, or on existing projects which are currently being prepared for submission. Chapter 2 looks at how external electric fields affect both oxidized and unoxidized lipid bilayers as a function of oxidation concentration and oxidized lipid type. Oxidative damage to cell membranes represents a physiologically relevant

  14. Modification of the CHARMM force field for DMPC lipid bilayer.

    Science.gov (United States)

    Högberg, Carl-Johan; Nikitin, Alexei M; Lyubartsev, Alexander P

    2008-11-15

    The CHARMM force field for DMPC lipids was modified in order to improve agreement with experiment for a number of important properties of hydrated lipid bilayer. The modification consists in introduction of a scaling factor 0.83 for 1-4 electrostatic interactions (between atoms separated by three covalent bonds), which provides correct transgauche ratio in the alkane tails, and recalculation of the headgroup charges on the basis of HF/6-311(d,p) ab-initio computations. Both rigid TIP3P and flexible SPC water models were used with the new lipid model, showing similar results. The new model in a 75 ns simulation has shown a correct value of the area per lipid at zero surface tension, as well as good agreement with the experiment for the electron density, structure factor, and order parameters, including those in the headgroup part of lipids. 2008 Wiley Periodicals, Inc.

  15. Thermal and active fluctuations of a compressible bilayer vesicle

    Science.gov (United States)

    Sachin Krishnan, T. V.; Yasuda, Kento; Okamoto, Ryuichi; Komura, Shigeyuki

    2018-05-01

    We discuss thermal and active fluctuations of a compressible bilayer vesicle by using the results of hydrodynamic theory for vesicles. Coupled Langevin equations for the membrane deformation and the density fields are employed to calculate the power spectral density matrix of membrane fluctuations. Thermal contribution is obtained by means of the fluctuation dissipation theorem, whereas active contribution is calculated from exponentially decaying time correlation functions of active random forces. We obtain the total power spectral density as a sum of thermal and active contributions. An apparent response function is further calculated in order to compare with the recent microrheology experiment on red blood cells. An enhanced response is predicted in the low-frequency regime for non-thermal active fluctuations.

  16. Spin-Swapping Transport and Torques in Ultrathin Magnetic Bilayers

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2016-07-12

    Planar spin transport in disordered ultrathin magnetic bilayers comprising a ferromagnet and a normal metal (typically used for spin pumping, spin Seebeck and spin-orbit torque experiments) is investigated theoretically. Using a tight-binding model that puts the extrinsic spin Hall effect and spin swapping on equal footing, we show that the nature of spin-orbit coupled transport dramatically depends on the ratio between the layer thickness d and the mean free path λ. While the spin Hall effect dominates in the diffusive limit (d≫λ), spin swapping dominates in the Knudsen regime (d≲λ). A remarkable consequence is that spin swapping induces a substantial fieldlike torque in the Knudsen regime.

  17. Hyperspectral image classification through bilayer graph-based learning.

    Science.gov (United States)

    Gao, Yue; Ji, Rongrong; Cui, Peng; Dai, Qionghai; Hua, Gang

    2014-07-01

    Hyperspectral image classification with limited number of labeled pixels is a challenging task. In this paper, we propose a bilayer graph-based learning framework to address this problem. For graph-based classification, how to establish the neighboring relationship among the pixels from the high dimensional features is the key toward a successful classification. Our graph learning algorithm contains two layers. The first-layer constructs a simple graph, where each vertex denotes one pixel and the edge weight encodes the similarity between two pixels. Unsupervised learning is then conducted to estimate the grouping relations among different pixels. These relations are subsequently fed into the second layer to form a hypergraph structure, on top of which, semisupervised transductive learning is conducted to obtain the final classification results. Our experiments on three data sets demonstrate the merits of our proposed approach, which compares favorably with state of the art.

  18. Reconstitution of Cholesterol-Dependent Vaginolysin into Tethered Phospholipid Bilayers

    DEFF Research Database (Denmark)

    Budvytyte, Rima; Pleckaityte, M.; Zvirbliene, A.

    2013-01-01

    Functional reconstitution of the cholesterol-dependent cytolysin vaginolysin (VLY) from Gardnerella vaginalis into artificial tethered bilayer membranes (tBLMs) has been accomplished. The reconstitution of VLY was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes...... of the EIS parameters of the tBLMs upon exposure to VLY solutions were consistent with the formation of water-filled pores in the membranes. It was found that reconstitution of VLY is a strictly cholesterol-dependent, irreversible process. At a constant cholesterol concentration reconstitution of VLY...... substitutions led to noticeably lesser tBLM damage. Pre-incubation of VLY with the neutralizing monoclonal antibody 9B4 inactivated the VLY membrane damage in a concentration-dependent manner, while the non-neutralizing antibody 21A5 exhibited no effect. These findings demonstrate the biological relevance...

  19. Electrically Tunable Bandgaps in Bilayer MoS₂.

    Science.gov (United States)

    Chu, Tao; Ilatikhameneh, Hesameddin; Klimeck, Gerhard; Rahman, Rajib; Chen, Zhihong

    2015-12-09

    Artificial semiconductors with manufactured band structures have opened up many new applications in the field of optoelectronics. The emerging two-dimensional (2D) semiconductor materials, transition metal dichalcogenides (TMDs), cover a large range of bandgaps and have shown potential in high performance device applications. Interestingly, the ultrathin body and anisotropic material properties of the layered TMDs allow a wide range modification of their band structures by electric field, which is obviously desirable for many nanoelectronic and nanophotonic applications. Here, we demonstrate a continuous bandgap tuning in bilayer MoS2 using a dual-gated field-effect transistor (FET) and photoluminescence (PL) spectroscopy. Density functional theory (DFT) is employed to calculate the field dependent band structures, attributing the widely tunable bandgap to an interlayer direct bandgap transition. This unique electric field controlled spontaneous bandgap modulation approaching the limit of semiconductor-to-metal transition can open up a new field of not yet existing applications.

  20. Anti-ferromagnetic Heisenberg model on bilayer honeycomb

    International Nuclear Information System (INIS)

    Shoja, M.; Shahbazi, F.

    2012-01-01

    Recent experiment on spin-3/2 bilayer honeycomb lattice antiferromagnet Bi 3 Mn 4 O 12 (NO 3 ) shows a spin liquid behavior down to very low temperatures. This behavior can be ascribed to the frustration effect due to competitions between first and second nearest neighbour's antiferromagnet interaction. Motivated by the experiment, we study J 1 -J 2 Antiferromagnet Heisenberg model, using Mean field Theory. This calculation shows highly degenerate ground state. We also calculate the effect of second nearest neighbor through z direction and show these neighbors also increase frustration in these systems. Because of these degenerate ground state in these systems, spins can't find any ground state to be freeze in low temperatures. This behavior shows a novel spin liquid state down to very low temperatures.