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Sample records for nanoscale morphology determined

  1. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Borghi, F.; Lenardi, C.; Podestà, A.; Milani, P., E-mail: pmilani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Sogne, E. [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); European School of Molecular Medicine (SEMM), IFOM-IEO, Milano (Italy); Merlini, M. [Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, via Mangiagalli 32, 20133 Milano (Italy); Ducati, C. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2016-08-07

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

  2. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    International Nuclear Information System (INIS)

    Borghi, F.; Lenardi, C.; Podestà, A.; Milani, P.; Sogne, E.; Merlini, M.; Ducati, C.

    2016-01-01

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

  3. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    KAUST Repository

    Borghi, F.

    2016-08-05

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing.

  4. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    KAUST Repository

    Borghi, F.; Sogne, Elisa; Lenardi, C.; Podestà , A.; Merlini, M.; Ducati, C.; Milani, P.

    2016-01-01

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing.

  5. Controlling the nanoscale morphology of organic films deposited by polyatomic ions

    CERN Document Server

    Hanley, L; Fuoco, E R; Ahu-Akin, F; Wijesundara, M B J; Li, Maozhen; Tikhonov, A; Schlossman, M

    2003-01-01

    Hyperthermal polyatomic ion beams can be used to fabricate thin film nanostructures with controlled morphology. Several experiments are described in which mass-selected and non-mass-selected polyatomic ion beams are used to create nanometer thick films with controlled surface and buried interface morphologies. Fluorocarbon and thiophenic films are grown on silicon wafers and/or polystyrene from 5 to 200 eV C sub 3 F sub 5 sup + or C sub 4 H sub 4 S sup + ions, respectively. X-ray photoelectron spectroscopy, atomic force microscopy, X-ray reflectivity, and scanning electron microscopy are utilized to analyze the morphology and chemistry of these films. Polyatomic ions are found to control film morphology on the nanoscale through variation of the incident ion energy, ion structure and/or substrate.

  6. Visualizing nanoscale phase morphology for understanding photovoltaic performance of PTB7: PC71BM solar cell

    Science.gov (United States)

    Supasai, Thidarat; Amornkitbamrung, Vittaya; Thanachayanont, Chanchana; Tang, I.-Ming; Sutthibutpong, Thana; Rujisamphan, Nopporn

    2017-11-01

    Visualizing and controlling the phase separation of the donor and acceptor domains in organic bulk-hetero-junction (BHJ) solar devices made with poly([4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethyl-hexyl)carbon-yl]thieno[3,4-bthiophenediyl]) (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) are needed to achieve high power conversion efficiency (PCE). Traditional bright-field (BF) imaging, especially of polymeric materials, produces images of poor contrast when done at the nanoscale level. Clear nanoscale morphologies of the PTB7:PC71BM blends prepared with different 1,8-diiodooctane (DIO) concentrations were seen when using the energy-filtered transmission electron microscopy (EFTEM). The electron energy loss (EELS) spectra of the pure PTB7 and PC71BM samples are centered at 22.7 eV and 24.5 eV, respectively. Using the electrons whose energy losses are in the range of 16-30 eV, detail information of the phase morphology at the nanoscale was obtained. Correlations between the improvement in the photovoltaic performances and the increased electron mobility were seen. These correlations are discussed in terms of the changes (at the nanoscale level) in blending phase morphology when different DIO concentrations are added.

  7. Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.

    Directory of Open Access Journals (Sweden)

    Francesca Borghi

    Full Text Available We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2 surfaces in aqueous solutions. IsoElectric Points (IEPs of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces.

  8. Quantitative characterization of the influence of the nanoscale morphology of nanostructured surfaces on bacterial adhesion and biofilm formation.

    Directory of Open Access Journals (Sweden)

    Ajay Vikram Singh

    Full Text Available Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological

  9. Nanoscale morphological analysis of soft matter aggregates with fractal dimension ranging from 1 to 3.

    Science.gov (United States)

    Valle, Francesco; Brucale, Marco; Chiodini, Stefano; Bystrenova, Eva; Albonetti, Cristiano

    2017-09-01

    While the widespread emergence of nanoscience and nanotechnology can be dated back to the early eighties, the last decade has witnessed a true coming of age of this research field, with novel nanomaterials constantly finding their way into marketed products. The performance of nanomaterials being dominated by their nanoscale morphology, their quantitative characterization with respect to a number of properties is often crucial. In this context, those imaging techniques able to resolve nanometer scale details are clearly key players. In particular, atomic force microscopy can yield a fully quantitative tridimensional (3D) topography at the nanoscale. Herein, we will review a set of morphological analysis based on the scaling approach, which give access to important quantitative parameters for describing nanomaterial samples. To generalize the use of such morphological analysis on all D-dimensions (1D, 2D and 3D), the review will focus on specific soft matter aggregates with fractal dimension ranging from just above 1 to just below 3. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Nanoscale protein arrays of rich morphologies via self-assembly on chemically treated diblock copolymer surfaces

    International Nuclear Information System (INIS)

    Song Sheng; Milchak, Marissa; Zhou Hebing; Lee, Thomas; Hanscom, Mark; Hahm, Jong-in

    2013-01-01

    Well-controlled assembly of proteins on supramolecular templates of block copolymers can be extremely useful for high-throughput biodetection. We report the adsorption and assembly characteristics of a model antibody protein to various polystyrene-block-poly(4-vinylpyridine) templates whose distinctive nanoscale structures are obtained through time-regulated exposure to chloroform vapor. The strong adsorption preference of the protein to the polystyrene segment in the diblock copolymer templates leads to an easily predictable, controllable, rich set of nanoscale protein morphologies through self-assembly. We also demonstrate that the chemical identities of various subareas within individual nanostructures can be readily elucidated by investigating the corresponding protein adsorption behavior on each chemically distinct area of the template. In our approach, a rich set of intricate nanoscale morphologies of protein arrays that cannot be easily attained through other means can be generated straightforwardly via self-assembly of proteins on chemically treated diblock copolymer surfaces, without the use of clean-room-based fabrication tools. Our approach provides much-needed flexibility and versatility for the use of block copolymer-based protein arrays in biodetection. The ease of fabrication in producing well-defined and self-assembled templates can contribute to a high degree of versatility and simplicity in acquiring an intricate nanoscale geometry and spatial distribution of proteins in arrays. These advantages can be extremely beneficial both for fundamental research and biomedical detection, especially in the areas of solid-state-based, high-throughput protein sensing. (paper)

  11. High efficiency polymer solar cells with vertically modulated nanoscale morphology

    International Nuclear Information System (INIS)

    Kumar, Ankit; Hong Ziruo; Yang Yang; Li Gang

    2009-01-01

    Nanoscale morphology has been shown to be a critical parameter governing charge transport properties of polymer bulk heterojunction (BHJ) solar cells. Recent results on vertical phase separation have intensified the research on 3D morphology control. In this paper, we intend to modify the distribution of donors and acceptors in a classical BHJ polymer solar cell by making the active layer richer in donors and acceptors near the anode and cathode respectively. Here, we chose [6,6]-phenyl- C 61 -butyric acid methyl ester (PCBM) to be the acceptor material to be thermally deposited on top of [poly(3-hexylthiophene)] P3HT: the PCBM active layer to achieve a vertical composition gradient in the BHJ structure. Here we report on a solar cell with enhanced power conversion efficiency of 4.5% which can be directly correlated with the decrease in series resistance of the device.

  12. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth.

    Science.gov (United States)

    Brower, Landon J; Gentry, Lauren K; Napier, Amanda L; Anderson, Mary E

    2017-01-01

    Integration of surface-anchored metal-organic frameworks (surMOFs) within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm) initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm) covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  13. Tailoring the nanoscale morphology of HKUST-1 thin films via codeposition and seeded growth

    Directory of Open Access Journals (Sweden)

    Landon J. Brower

    2017-11-01

    Full Text Available Integration of surface-anchored metal-organic frameworks (surMOFs within hierarchical architectures is necessary for potential sensing, electronic, optical, or separation applications. It is important to understand the fundamentals of film formation for these surMOFs in order to develop strategies for their incorporation with nanoscale control over lateral and vertical dimensions. This research identified processing parameters to control the film morphology for surMOFs of HKUST-1 fabricated by codeposition and seeded deposition. Time and temperature were investigated to observe film formation, to control film thickness, and to tune morphology. Film thickness was investigated by ellipsometry, while film structure and film roughness were characterized by atomic force microscopy. Films formed via codeposition resulted in nanocrystallites anchored to the gold substrate. A dynamic process at the interface was observed with a low density of large particulates (above 100 nm initially forming on the substrate; and over time these particulates were slowly replaced by the prevalence of smaller crystallites (ca. 10 nm covering the substrate at a high density. Elevated temperature was found to expedite the growth process to obtain the full range of surface morphologies with reasonable processing times. Seed crystals formed by the codeposition method were stable and nucleated growth throughout a subsequent layer-by-layer deposition process. These seed crystals templated the final film structure and tailor the features in lateral and vertical directions. Using codeposition and seeded growth, different surface morphologies with controllable nanoscale dimensions can be designed and fabricated for integration of MOF systems directly into device architectures and sensor platforms.

  14. Recent Approaches to Controlling the Nanoscale Morphology of Polymer-Based Bulk-Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Abdulra'uf Lukman Bola

    2013-11-01

    Full Text Available The need for clean, inexpensive and renewable energy has increasingly turned research attention towards polymer photovoltaic cells. However, the performance efficiency of these devices is still low in comparison with silicon-based devices. The recent introduction of new materials and processing techniques has resulted in a remarkable increase in power-conversion efficiency, with a value above 10%. Controlling the interpenetrating network morphology is a key factor in obtaining devices with improved performance. This review focuses on the influence of controlled nanoscale morphology on the overall performance of bulk-heterojunction (BHJ photovoltaic cells. Strategies such as the use of solvents, solvent annealing, polymer nanowires (NWs, and donor–acceptor (D–A blend ratios employed to control the active-layer morphologies are all discussed.

  15. Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Armas-Pérez, Julio C. [Institute; División; Li, Xiao [Institute; Martínez-González, José A. [Institute; Smith, Coleman [Institute; Hernández-Ortiz, J. P. [Departamento; Nealey, Paul F. [Institute; Materials; de Pablo, Juan J. [Institute; Materials

    2017-08-17

    Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.

  16. Nanoscale morphology of Ni{sub 50}Ti{sub 45}Cu{sub 5} nanoglass

    Energy Technology Data Exchange (ETDEWEB)

    Śniadecki, Z., E-mail: sniadecki@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Wang, D. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Ivanisenko, Yu. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Chakravadhanula, V.S.K. [Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Helmholtz Institute Ulm, Helmholtzstraße 11, 89081, Ulm (Germany); Joint Research Laboratory Nanomaterials (KIT-TUD), Institute of Materials Science, TU Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt (Germany); Kübel, C. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Hahn, H. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Joint Research Laboratory Nanomaterials (KIT-TUD), Institute of Materials Science, TU Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt (Germany); Nanjing University of Science and Technology, Herbert Gleiter Institute of Nanoscience, Building 340, Nanjing, Jiangsu 2 10094 (China); and others

    2016-03-15

    Nanoglasses are noncrystalline solids with a granular nano-/microstructure. In contrast to their nanocrystalline analogs, typically constituted of grains and grain boundaries, nanoglasses consist of glassy regions with a structure corresponding to melt-quenched glasses and amorphous interfaces characterized by a reduced density. Their unique properties can be controlled by modifying size and chemical composition of the granular and interfacial regions. Ni{sub 50}Ti{sub 45}Cu{sub 5} amorphous films were obtained by magnetron sputtering and analyzed to determine their nanoscale morphology and the formation mechanisms. The nanoglasses were noted to have a hierarchical nano-columnar structure with the smallest Ni-rich (Ni:Ti ratio of ca. 5:3) amorphous columns with diameters of about 8 nm and Ti-rich glassy interfacial regions with a substantially lower density. The results were obtained utilizing X-ray diffraction and different microscopic methods, e.g., atomic force microscopy and transmission electron microscopy. A detailed analysis indicates the complexity of the formation mechanisms of topologically and chemically distinguishable structural units with curvature driven surface diffusion, surface mobility, self-shadowing and internal stresses as the most important parameters. Common and simple synthesis method and the possibility for easy modification of the morphology and, consequently, the physical properties offer an opportunity for intensive studies of this new class of materials, opening the way towards possible applications. - Highlights: • Ni{sub 50}Ti{sub 45}Cu{sub 5} thin film nanoglasses were synthesized by magnetron sputtering. • Ti amorphous interfacial phase with reduced density is observed. • Stabilization of interfaces by specific local thermodynamic conditions.

  17. Predictive modeling of nanoscale domain morphology in solution-processed organic thin films

    Science.gov (United States)

    Schaaf, Cyrus; Jenkins, Michael; Morehouse, Robell; Stanfield, Dane; McDowall, Stephen; Johnson, Brad L.; Patrick, David L.

    2017-09-01

    The electronic and optoelectronic properties of molecular semiconductor thin films are directly linked to their extrinsic nanoscale structural characteristics such as domain size and spatial distributions. In films prepared by common solution-phase deposition techniques such as spin casting and solvent-based printing, morphology is governed by a complex interrelated set of thermodynamic and kinetic factors that classical models fail to adequately capture, leaving them unable to provide much insight, let alone predictive design guidance for tailoring films with specific nanostructural characteristics. Here we introduce a comprehensive treatment of solution-based film formation enabling quantitative prediction of domain formation rates, coverage, and spacing statistics based on a small number of experimentally measureable parameters. The model combines a mean-field rate equation treatment of monomer aggregation kinetics with classical nucleation theory and a supersaturation-dependent critical nucleus size to solve for the quasi-two-dimensional temporally and spatially varying monomer concentration, nucleation rate, and other properties. Excellent agreement is observed with measured nucleation densities and interdomain radial distribution functions in polycrystalline tetracene films. Numerical solutions lead to a set of general design rules enabling predictive morphological control in solution-processed molecular crystalline films.

  18. The influence of nanoscale morphology on the resistivity of cluster-assembled nanostructured metallic thin films

    International Nuclear Information System (INIS)

    Barborini, E; Bertolini, G; Repetto, P; Leccardi, M; Vinati, S; Corbelli, G; Milani, P

    2010-01-01

    We have studied in situ the evolution of the electrical resistivity of Fe, Pd, Nb, W and Mo cluster-assembled films during their growth by supersonic cluster beam deposition. We observed resistivity of cluster-assembled films several orders of magnitude larger than the bulk, as well as an increase in resistivity by increasing the film thickness in contrast to what was observed for atom-assembled metallic films. This suggests that the nanoscale morphological features typical of ballistic films growth, such as the minimal cluster-cluster interconnection and the evolution of surface roughness with thickness, are responsible for the observed behaviour.

  19. Naphtho[2,1-b:3,4-b']dithiophene-based bulk heterojunction solar cells: how molecular structure influences nanoscale morphology and photovoltaic properties.

    Science.gov (United States)

    Kim, Yu Jin; Cheon, Ye Rim; Back, Jang Yeol; Kim, Yun-Hi; Chung, Dae Sung; Park, Chan Eon

    2014-11-10

    Organic bulk heterojunction photovoltaic devices based on a series of three naphtho[2,1-b:3,4-b']dithiophene (NDT) derivatives blended with phenyl-C71-butyric acid methyl ester were studied. These three derivatives, which have NDT units with various thiophene-chain lengths, were employed as the donor polymers. The influence of their molecular structures on the correlation between their solar-cell performances and their degree of crystallization was assessed. The grazing-incidence angle X-ray diffraction and atomic force microscopy results showed that the three derivatives exhibit three distinct nanoscale morphologies. We correlated these morphologies with the device physics by determining the J-V characteristics and the hole and electron mobilities of the devices. On the basis of our results, we propose new rules for the design of future generations of NDT-based polymers for use in bulk heterojunction solar cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Multiscale Morphology of Nanoporous Copper Made from Intermetallic Phases

    International Nuclear Information System (INIS)

    Egle, Tobias; Harvard University, Cambridge, MA; Barroo, Cédric; Janvelyan, Nare; Baumgaertel, Andreas C.

    2017-01-01

    Many application-relevant properties of nanoporous metals critically depend on their multiscale architecture. For example, the intrinsically high step-edge density of curved surfaces at the nanoscale provides highly reactive sites for catalysis, whereas the macroscale pore and grain morphology determines the macroscopic properties, such as mass transport, electrical conductivity, or mechanical properties. Here, in this work, we systematically study the effects of alloy composition and dealloying conditions on the multiscale morphology of nanoporous copper (np-Cu) made from various commercial Zn–Cu precursor alloys. Using a combination of X-ray diffraction, electron backscatter diffraction, and focused ion beam cross-sectional analysis, our results reveal that the macroscopic grain structure of the starting alloy surprisingly survives the dealloying process, despite a change in crystal structure from body-centered cubic (Zn–Cu starting alloy) to face-centered cubic (Cu). The nanoscale structure can be controlled by the acid used for dealloying with HCl leading to a larger and more faceted ligament morphology compared to that of H_3PO_4. Finally, anhydrous ethanol dehydrogenation was used as a probe reaction to test the effect of the nanoscale ligament morphology on the apparent activation energy of the reaction.

  1. The effect of cycling on the nanoscale morphology and redox properties of poly[2,2′-bithiophene

    International Nuclear Information System (INIS)

    O’Neil, K.D.; Smith, A.; Forristal, T.A.; Semenikhin, O.A.

    2013-01-01

    The changes in the redox behavior and nanoscale morphology of poly[2,2′-bithiophene] deposited onto highly oriented pyrolytic graphite substrates upon repeated doping–undoping were studied. It was shown that repeated cycling resulted in very particular changes in the voltammetric response of the polymer films as well as their nanoscale morphology. Specifically, when the cycling was performed to relatively low anodic potentials, the overall doping–undoping charge did not change; however, the shape of voltammograms was consistently changing showing broadening of the voltammograms and reducing of the doping peak height in the anodic scan, as well as broadening and deterioration of the undoping peak in the reverse scan. Furthermore, a remarkable feature was observed that all voltammogram traces intersected at several characteristic potentials producing quasi-isosbestic points. With an increase in the anodic scan potential limit, the overall doping–undoping charge starts to decrease showing irreversible degradation of the polymer; however, the general pattern of the peak broadening could be still observed. Atomic force microscopic (AFM) studies of the polymer films cycled to various anodic limits showed that repeated cycling resulted in a gradual decrease in the degree of crystallinity, as revealed by AFM phase imaging, and an increase in the degree of disorder. Coupled with the changes in the redox behavior, these findings suggested the formation of more flexible and open polymer nanostructure that enables easier penetration of the dopant ions and solvent. However, at the same time, an increase in the degree of disorder reduced the interchain interactions and inhibited the formation of extended electronic states delocalized across neighboring polymer chains. This occurred at first without irreversible degradation of the polymer and a decrease in the overall doping–undoping charge. Cycling to higher anodic potentials resulted in irreversible degradation

  2. Macroscale and Nanoscale Morphology Evolution during in Situ Spray Coating of Titania Films for Perovskite Solar Cells.

    Science.gov (United States)

    Su, Bo; Caller-Guzman, Herbert A; Körstgens, Volker; Rui, Yichuan; Yao, Yuan; Saxena, Nitin; Santoro, Gonzalo; Roth, Stephan V; Müller-Buschbaum, Peter

    2017-12-20

    Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol-gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not only on micellization but also on solvent evaporation during the spray coating. Perovskite (CH 3 NH 3 PbI 3 ) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

  3. Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

    KAUST Repository

    Kumar, Naresh

    2017-01-12

    Novel optoelectronic devices rely on complex nanomaterial systems where the nanoscale morphology and local chemical composition are critical to performance. However, the lack of analytical techniques that can directly probe these structure-property relationships at the nanoscale presents a major obstacle to device development. In this work, we present a novel method for non-destructive, simultaneous mapping of the morphology, chemical composition and photoelectrical properties with <20 nm spatial resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale resolution in all three spatial dimensions. By applying the technique to an organic solar cell device, we show that the inferred surface and subsurface composition distribution correlates strongly with the local photocurrent generation and explains macroscopic device performance. For instance, the direct measurement of fullerene phase purity can distinguish between high purity aggregates that lead to poor performance and lower purity aggregates (fullerene intercalated with polymer) that result in strong photocurrent generation and collection. We show that the reliable determination of the structure-property relationship at the nanoscale can remove ambiguity from macroscopic device data and support the identification of the best routes for device optimisation. The multi-parameter measurement approach demonstrated herein is expected to play a significant role in guiding the rational design of nanomaterial-based optoelectronic devices, by opening a new realm of possibilities for advanced investigation via the combination of nanoscale optical spectroscopy with a whole range of scanning probe microscopy modes.

  4. Nanoscale conductive pattern of the homoepitaxial AlGaN/GaN transistor.

    Science.gov (United States)

    Pérez-Tomás, A; Catalàn, G; Fontserè, A; Iglesias, V; Chen, H; Gammon, P M; Jennings, M R; Thomas, M; Fisher, C A; Sharma, Y K; Placidi, M; Chmielowska, M; Chenot, S; Porti, M; Nafría, M; Cordier, Y

    2015-03-20

    The gallium nitride (GaN)-based buffer/barrier mode of growth and morphology, the transistor electrical response (25-310 °C) and the nanoscale pattern of a homoepitaxial AlGaN/GaN high electron mobility transistor (HEMT) have been investigated at the micro and nanoscale. The low channel sheet resistance and the enhanced heat dissipation allow a highly conductive HEMT transistor (Ids > 1 A mm(-1)) to be defined (0.5 A mm(-1) at 300 °C). The vertical breakdown voltage has been determined to be ∼850 V with the vertical drain-bulk (or gate-bulk) current following the hopping mechanism, with an activation energy of 350 meV. The conductive atomic force microscopy nanoscale current pattern does not unequivocally follow the molecular beam epitaxy AlGaN/GaN morphology but it suggests that the FS-GaN substrate presents a series of preferential conductive spots (conductive patches). Both the estimated patches density and the apparent random distribution appear to correlate with the edge-pit dislocations observed via cathodoluminescence. The sub-surface edge-pit dislocations originating in the FS-GaN substrate result in barrier height inhomogeneity within the HEMT Schottky gate producing a subthreshold current.

  5. Nanoscale Mechanical Stimulation of Human Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    H Nikukar

    2014-05-01

    We observed significant responses after 1 and 2-week stimulations in cell number, cell shapes and phenotypical markers. Microarray was performed for all groups. Cell count showed normal cell growth with stimulation. However, cell surface area, cell perimeter, and arboration after 1-week stimulation showed significant increases. Immunofluorescent studies have showed significant increase in osteocalcin production after stimulation. Conclusions: Nanoscale mechanical vibration showed significant changes in human mesenchymal stem cell behaviours. Cell morphology changed to become more polygonal and increased expression of the osteoblast markers were noted. These findings with gene regulation changes suggesting nanoscale mechanostimulation has stimulated osteoblastogenesis.  Keywords:  Mesenchymal, Nanoscale, Stem Cells.

  6. Ultrafast Charge and Triplet State Formation in Diketopyrrolopyrrole Low Band Gap Polymer/Fullerene Blends: Influence of Nanoscale Morphology of Organic Photovoltaic Materials on Charge Recombination to the Triplet State

    Directory of Open Access Journals (Sweden)

    René M. Williams

    2017-01-01

    Full Text Available Femtosecond transient absorption spectroscopy of thin films of two types of morphologies of diketopyrrolopyrrole low band gap polymer/fullerene-adduct blends is presented and indicates triplet state formation by charge recombination, an important loss channel in organic photovoltaic materials. At low laser fluence (approaching solar intensity charge formation characterized by a 1350 nm band (in ~250 fs dominates in the two PDPP-PCBM blends with different nanoscale morphologies and these charges recombine to form a local polymer-based triplet state on the sub-ns timescale (in ~300 and ~900 ps indicated by an 1100 nm absorption band. The rate of triplet state formation is influenced by the morphology. The slower rate of charge recombination to the triplet state (in ~900 ps belongs to a morphology that results in a higher power conversion efficiency in the corresponding device. Nanoscale morphology not only influences interfacial area and conduction of holes and electrons but also influences the mechanism of intersystem crossing (ISC. We present a model that correlates morphology to the exchange integral and fast and slow mechanisms for ISC (SOCT-ISC and H-HFI-ISC. For the pristine polymer, a flat and unstructured singlet-singlet absorption spectrum (between 900 and 1400 nm and a very minor triplet state formation (5% are observed at low laser fluence.

  7. Morphological Characteristics of Au Films Deposited on Ti: A Combined SEM-AFM Study

    Directory of Open Access Journals (Sweden)

    Francesco Ruffino

    2018-03-01

    Full Text Available Deposited Au films and coatings are, nowadays, routinely used as active or passive elements in several innovative electronic, optoelectronic, sensing, and energy devices. In these devices, the physical properties of the Au films are strongly determined by the films nanoscale structure. In addition, in these devices, often, a layer of Ti is employed to promote adhesion and, so, influencing the nanoscale structure of the deposited Au film. In this work, we present experimental analysis on the nanoscale cross-section and surface morphology of Au films deposited on Ti. In particular, we sputter-deposited thick (>100 nm thickness Au films on Ti foils and we used Scanning Electron Microscopy to analyze the films cross-sectional and surface morphology as a function of the Au film thickness and deposition angle. In addition, we analyzed the Au films surface morphology by Atomic Force Microscopy which allowed quantifying the films surface roughness versus the film thickness and deposition angle. The results establish a relation between the Au films cross-sectional and surface morphologies and surface roughness to the film thickness and deposition angle. These results allow setting a general working framework to obtain Au films on Ti with specific morphological and topographic properties for desired applications in which the Ti adhesion layer is needed for Au.

  8. Understanding the effects of strain on morphological instabilities of a nanoscale island during heteroepitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Lu; Wang, Jing; Wang, Shibin; Li, Linan; Shen, Min; Wang, Zhiyong; Chen, Zhenfei; Zhao, Yang [Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072 (China); Department of Mechanics, Tianjin University, Tianjin 300072 (China)

    2015-07-21

    A comprehensive morphological stability analysis of a nanoscale circular island during heteroepitaxial growth is presented based on continuum elasticity theory. The interplay between kinetic and thermodynamic mechanisms is revealed by including strain-related kinetic processes. In the kinetic regime, the Burton-Cabrera-Frank model is adopted to describe the growth front of the island. Together with kinetic boundary conditions, various kinetic processes including deposition flow, adatom diffusion, attachment-detachment kinetics, and the Ehrlich-Schwoebel barrier can be taken into account at the same time. In the thermodynamic regime, line tension, surface energy, and elastic energy are considered. As the strain relief in the early stages of heteroepitaxy is more complicated than commonly suggested by simple consideration of lattice mismatch, we also investigate the effects of external applied strain and elastic response due to perturbations on the island shape evolution. The analytical expressions for elastic fields induced by mismatch strain, external applied strain, and relaxation strain are presented. A systematic approach is developed to solve the system via a perturbation analysis which yields the conditions of film morphological instabilities. Consistent with previous experimental and theoretical work, parametric studies show the kinetic evolution of elastic relaxation, island morphology, and film composition under various conditions. Our present work offers an effective theoretical approach to get a comprehensive understanding of the interplay between different growth mechanisms and how to tailor the growth mode by controlling the nature of the crucial factors.

  9. Identification of nanoscale structure and morphology reconstruction in oxidized a-SiC:H thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vasin, A.V.; Rusavsky, A.V.; Nazarov, A.N.; Lysenko, V.S.; Lytvyn, P.M.; Strelchuk, V.V. [Lashkaryov Institute of Semiconductor Physics, 41 Nauki Pr., Kiev 03028 (Ukraine); Kholostov, K.I.; Bondarenko, V.P. [Belarusian State University of Informatics and Radioelectronics, 6P. Brovki Str., Minsk 220013 (Belarus); Starik, S.P. [Bakul Institute of Superhard Materials, 2 Avtzavodskaya Str., Kiev 04074 (Ukraine)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer Increase of magnetron discharge power results in densification of a-SiC:H thin films. Black-Right-Pointing-Pointer The denser a-SiC:H material the better resistance to oxidation by oxygen. Black-Right-Pointing-Pointer Oxidation of soft a-SiC:H films can result in increase of electric conductivity. Black-Right-Pointing-Pointer Formation of graphitic clusters was found in a-SiC:H after annealing in oxygen. - Abstract: Oxidation behavior of a-SiC:H layers deposited by radio-frequency magnetron sputtering technique was examined by Kelvin probe force microscopy (KPFM) in combination with scanning electron microscopy, Fourier-transform infra-red spectroscopy and submicron selected area Raman scattering spectroscopy. Partially oxidized a-SiC:H samples (oxidation at 600 Degree-Sign C in oxygen) were examined to clarify mechanism of the oxidation process. Nanoscale and microscale morphological defects (pits) with dimension of about 50 nm and several microns respectively have appeared after thermal treatment. KPFM measurements exhibited the surface potential of the material in micro pits is significantly smaller in comparison with surrounding material. Submicron RS measurements indicates formation of graphite-like nano-inclusions in the pit defects. We conclude that initial stage of oxidation process in a-SiC:H films takes place not homogeneously throughout the layer but it is initiated in local nanoscale regions followed by spreading over all layer.

  10. Nanoscale Morphology Evolution Under Ion Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Michael J. [President & Fellows of Harvard College, Cambridge, MA (United States)

    2014-11-10

    We showed that the half-century-old paradigm of morphological instability under irradiation due to the curvature-dependence of the sputter yield, can account neither for the phase diagram nor the amplification or decay rates that we measure in the simplest possible experimental system -- an elemental semiconductor with an amorphous surface under noble-gas ion irradiation; We showed that a model of pattern formation based on the impact-induced redistribution of atoms that do not get sputtered away explains our experimental observations; We developed a first-principles, parameter-free approach for predicting morphology evolution, starting with molecular dynamics simulations of single ion impacts, lasting picoseconds, and upscaling through a rigorous crater-function formalism to develop a partial differential equation that predicts morphology evolution on time scales more than twelve orders of magnitude longer than can be covered by the molecular dynamics; We performed the first quantitative comparison of the contributions to morphological instability from sputter removal and from impact-induced redistribution of atoms that are removed, and showed that the former is negligible compared to the latter; We established a new paradigm for impact-induced morphology evolution based on crater functions that incorporate both redistribution and sputter effects; and We developed a model of nanopore closure by irradiation-induced stress and irradiationenhanced fluidity, for the near-surface irradiation regime in which nuclear stopping predominates, and showed that it explains many aspects of pore closure kinetics that we measure experimentally.

  11. Internal Morphologies of Cycled Li-Metal Electrodes Investigated by Nano-Scale Resolution X-ray Computed Tomography.

    Science.gov (United States)

    Frisco, Sarah; Liu, Danny X; Kumar, Arjun; Whitacre, Jay F; Love, Corey T; Swider-Lyons, Karen E; Litster, Shawn

    2017-06-07

    While some commercially available primary batteries have lithium metal anodes, there has yet to be a commercially viable secondary battery with this type of electrode. Research prototypes of these cells typically exhibit a limited cycle life before dendrites form and cause internal cell shorting, an occurrence that is more pronounced during high-rate cycling. To better understand the effects of high-rate cycling that can lead to cell failure, we use ex situ nanoscale-resolution X-ray computed tomography (nano-CT) with the aid of Zernike phase contrast to image the internal morphologies of lithium metal electrodes on copper wire current collectors that have been cycled at low and high current densities. The Li that is deposited on a Cu wire and then stripped and deposited at low current density appears uniform in morphology. Those cycled at high current density undergo short voltage transients to >3 V during Li-stripping from the electrode, during which electrolyte oxidation and Cu dissolution from the current collector may occur. The effect of temperature is also explored with separate cycling experiments performed at 5 and 33 °C. The resulting morphologies are nonuniform films filled with voids that are semispherical in shape with diameters ranging from hundreds of nanometers to tens of micrometers, where the void size distributions are temperature-dependent. Low-temperature cycling elicits a high proportion of submicrometer voids, while the higher-temperature sample morphology is dominated by voids larger than 2 μm. In evaluating these morphologies, we consider the importance of nonidealities during extreme charging, such as electrolyte decomposition. We conclude that nano-CT is an effective tool for resolving features and aggressive cycling-induced anomalies in Li films in the range of 100 nm to 100 μm.

  12. Identification of Characteristic Macromolecules of Escherichia coli Genotypes by Atomic Force Microscope Nanoscale Mechanical Mapping

    Science.gov (United States)

    Chang, Alice Chinghsuan; Liu, Bernard Haochih

    2018-02-01

    The categorization of microbial strains is conventionally based on the molecular method, and seldom are the morphological characteristics in the bacterial strains studied. In this research, we revealed the macromolecular structures of the bacterial surface via AFM mechanical mapping, whose resolution was not only determined by the nanoscale tip size but also the mechanical properties of the specimen. This technique enabled the nanoscale study of membranous structures of microbial strains with simple specimen preparation and flexible working environments, which overcame the multiple restrictions in electron microscopy and label-enable biochemical analytical methods. The characteristic macromolecules located among cellular surface were considered as surface layer proteins and were found to be specific to the Escherichia coli genotypes, from which the averaged molecular sizes were characterized with diameters ranging from 38 to 66 nm, and the molecular shapes were kidney-like or round. In conclusion, the surface macromolecular structures have unique characteristics that link to the E. coli genotype, which suggests that the genomic effects on cellular morphologies can be rapidly identified using AFM mechanical mapping. [Figure not available: see fulltext.

  13. Electrical characterization and nanoscale surface morphology of optimized Ti/Al/Ta/Au ohmic contact for AlGaN/GaN HEMT.

    Science.gov (United States)

    Wang, Cong; Kim, Nam-Young

    2012-02-07

    Good ohmic contacts with low contact resistance, smooth surface morphology, and a well-defined edge profile are essential to ensure optimal device performances for the AlGaN/GaN high electron mobility transistors [HEMTs]. A tantalum [Ta] metal layer and an SiNx thin film were used for the first time as an effective diffusion barrier and encapsulation layer in the standard Ti/Al/metal/Au ohmic metallization scheme in order to obtain high quality ohmic contacts with a focus on the thickness of Ta and SiNx. It is found that the Ta thickness is the dominant factor affecting the contact resistance, while the SiNx thickness affects the surface morphology significantly. An optimized Ti/Al/Ta/Au ohmic contact including a 40-nm thick Ta barrier layer and a 50-nm thick SiNx encapsulation layer is preferred when compared with the other conventional ohmic contact stacks as it produces a low contact resistance of around 7.27 × 10-7 Ω·cm2 and an ultra-low nanoscale surface morphology with a root mean square deviation of around 10 nm. Results from the proposed study play an important role in obtaining excellent ohmic contact formation in the fabrication of AlGaN/GaN HEMTs.

  14. Novel multiform morphologies of hydroxyapatite: Synthesis and growth mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Mary, I. Reeta [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Department of Physics, Government Arts College, Coimbatore 641018 (India); Sonia, S.; Viji, S.; Mangalaraj, D.; Viswanathan, C. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Ponpandian, N., E-mail: ponpandian@buc.edu.in [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India)

    2016-01-15

    Graphical abstract: - Highlights: • Novel multiform morphologies of hydroxyapatite from nanoscale building blocks. • Facile hydro/solvothermal method under mild reaction conditions without the necessity of post-annealing treatment. • Growth mechanism by Ostwald ripening and self-assembly processes. - Abstract: Morphological evolution of materials becomes a prodigious challenge due to their key role in defining their functional properties and desired applications. Herein, we report the synthesis of hydroxyapatite (HAp) microstructures with multiform morphologies, such as spheres, cubes, hexagonal rods and nested bundles constructed from their respective nanoscale building blocks via a simple cost effective hydro/solvothermal method. A possible formation mechanism of diverse morphologies of HAp has been presented. Structural analysis based on X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirms the purity of the HAp microstructures. The multiform morphologies of HAp were corroborated by using Field emission scanning electron microscope (FESEM).

  15. Physical controls on directed virus assembly at nanoscale chemical templates

    International Nuclear Information System (INIS)

    Cheung, C L; Chung, S; Chatterji, A; Lin, T; Johnson, J E; Hok, S; Perkins, J; De Yoreo, J

    2006-01-01

    Viruses are attractive building blocks for nanoscale heterostructures, but little is understood about the physical principles governing their directed assembly. In-situ force microscopy was used to investigate organization of Cowpea Mosaic Virus engineered to bind specifically and reversibly at nanoscale chemical templates with sub-30nm features. Morphological evolution and assembly kinetics were measured as virus flux and inter-viral potential were varied. The resulting morphologies were similar to those of atomic-scale epitaxial systems, but the underlying thermodynamics was analogous to that of colloidal systems in confined geometries. The 1D templates biased the location of initial cluster formation, introduced asymmetric sticking probabilities, and drove 1D and 2D condensation at subcritical volume fractions. The growth kinetics followed a t 1/2 law controlled by the slow diffusion of viruses. The lateral expansion of virus clusters that initially form on the 1D templates following introduction of polyethylene glycol (PEG) into the solution suggests a significant role for weak interaction

  16. Sonochemical Synthesis of Photoluminescent Nanoscale Eu(III-Containing Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Cheng-an TAO

    2015-11-01

    Full Text Available Nanoscale lanthanide-containing metal-organic frameworks (MOFs have more and more interest due to their great properties and potential applications, but how to construct them easily is still challenging. Here, we present a facile and rapid synthesis of Eu(III-containing Nanoscale MOF (denoted as NMOF under ultrasonic irradiation. The effect of the ratio and the addition order of metal ions and linkers on the morphology and size of MOFs was investigated. It is found that both of the ratio and the addition order can affect the morphology and size of 1.4-benzenedicarboxylic acid(H2BDC -based MOFs, but they show no evident influence on that of H2aBDC-based MOFs. The former exhibit typical emission bands of Eu(III ions, while the latter only show the photoluminescent properties of ligands.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9695

  17. Effect of nano-scale morphology on micro-channel wall surface and electrical characterization in lead silicate glass micro-channel plate

    Science.gov (United States)

    Cai, Hua; Li, Fangjun; Xu, Yanglei; Bo, Tiezhu; Zhou, Dongzhan; Lian, Jiao; Li, Qing; Cao, Zhenbo; Xu, Tao; Wang, Caili; Liu, Hui; Li, Guoen; Jia, Jinsheng

    2017-10-01

    Micro-channel plate (MCP) is a two dimensional arrays of microscopic channel charge particle multiplier. Silicate composition and hydrogen reduction are keys to determine surface morphology of micro-channel wall in MCP. In this paper, lead silicate glass micro-channel plates in two different cesium contents (0at%, 0.5at%) and two different hydrogen reduction temperatures (400°C,450°C) were present. The nano-scale morphology, elements content and chemical states of microporous wall surface treated under different alkaline compositions and reduction conditions was investigated by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS), respectively. Meanwhile, the electrical characterizations of MCP, including the bulk resistance, electron gain and the density of dark current, were measured in a Vacuum Photoelectron Imaging Test Facility (VPIT).The results indicated that the granular phase occurred on the surface of microporous wall and diffuses in bulk glass is an aggregate of Pb atom derived from the reduction of Pb2+. In micro-channel plate, the electron gain and bulk resistance were mainly correlated to particle size and distribution, the density of dark current (DDC) went up with the increasing root-mean-square roughness (RMS) on the microporous wall surface. Adding cesiums improved the size of Pb atomic aggregation, lowered the relative concentration of [Pb] reduced from Pb2+ and decreased the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a less dark current. Increasing hydrogen reduction temperature also improved the size of Pb atomic aggregation, but enhanced the relative concentration of [Pb] and enlarged the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a larger dark current. The reasons for the difference of electrical characteristics were discussed.

  18. Exploring Chondrule and CAI Rims Using Micro- and Nano-Scale Petrological and Compositional Analysis

    Science.gov (United States)

    Cartwright, J. A.; Perez-Huerta, A.; Leitner, J.; Vollmer, C.

    2017-12-01

    As the major components within chondrites, chondrules (mm-sized droplets of quenched silicate melt) and calcium-aluminum-rich inclusions (CAI, refractory) represent the most abundant and the earliest materials that solidified from the solar nebula. However, the exact formation mechanisms of these clasts, and whether these processes are related, remains unconstrained, despite extensive petrological and compositional study. By taking advantage of recent advances in nano-scale tomographical techniques, we have undertaken a combined micro- and nano-scale study of CAI and chondrule rim morphologies, to investigate their formation mechanisms. The target lithologies for this research are Wark-Lovering rims (WLR), and fine-grained rims (FGR) around CAIs and chondrules respectively, present within many chondrites. The FGRs, which are up to 100 µm thick, are of particular interest as recent studies have identified presolar grains within them. These grains predate the formation of our Solar System, suggesting FGR formation under nebular conditions. By contrast, WLRs are 10-20 µm thick, made of different compositional layers, and likely formed by flash-heating shortly after CAI formation, thus recording nebular conditions. A detailed multi-scale study of these respective rims will enable us to better understand their formation histories and determine the potential for commonality between these two phases, despite reports of an observed formation age difference of up to 2-3 Myr. We are using a combination of complimentary techniques on our selected target areas: 1) Micro-scale characterization using standard microscopic and compositional techniques (SEM-EBSD, EMPA); 2) Nano-scale characterization of structures using transmission electron microscopy (TEM) and elemental, isotopic and tomographic analysis with NanoSIMS and atom probe tomography (APT). Preliminary nano-scale APT analysis of FGR morphologies within the Allende carbonaceous chondrite has successfully discerned

  19. Nanoscale synthesis and characterization of graphene-based objects

    Directory of Open Access Journals (Sweden)

    Daisuke Fujita

    2011-01-01

    Full Text Available Graphene-based nano-objects such as nanotrenches, nanowires, nanobelts and nanoscale superstructures have been grown by surface segregation and precipitation on carbon-doped mono- and polycrystalline nickel substrates in ultrahigh vacuum. The dominant morphologies of the nano-objects were nanowire and nanosheet. Nucleation of graphene sheets occurred at surface defects such as step edges and resulted in the directional growth of nanowires. Surface analysis by scanning tunneling microscopy (STM has clarified the structure and functionality of the novel nano-objects at atomic resolution. Nanobelts were detected consisting of bilayer graphene sheets with a nanoscale width and a length of several microns. Moiré patterns and one-dimensional reconstruction were observed on multilayer graphite terraces. As a useful functionality, application to repairable high-resolution STM probes is demonstrated.

  20. Droplet-fused microreactors for room temperature synthesis of nanoscale needle-like hydroxyapatite

    International Nuclear Information System (INIS)

    Liu Kaiying; Qin Jianhua

    2013-01-01

    A microfluidic device using droplet-fused microreactors is introduced for room temperature synthesis of nanoscale needle-shaped hydroxyapatite (HAp, Ca 10 (PO 4 ) 6 (OH) 2 ). The device is integrated with multifunctional units, e.g., T-junctions for droplet generation and fusion, winding channels for rapid mixing, and a delay line for simple visualization of the HAp formation process. The necessary conditions such as surfactant and fluid flow rate for an aqueous stream to merge with water-in-oil droplets are investigated. The nanoscale morphologies of the HAp produced by this method are also compared with HAp prepared by conventional bulk mixing. This paper shows that further reaction could be initiated by flowing additional reagent streams directly into the droplets of the initial reaction mixture, which is a novel approach for synthesizing a needle-like morphology of the HAp with a high aspect ratio under room temperature. (paper)

  1. Probing and tuning the size, morphology, chemistry and structure of nanoscale cerium oxide

    Science.gov (United States)

    Kuchibhatla, Satyanarayana Vnt

    Cerium oxide (ceria)-based materials in the nanoscale regime are of significant fundamental and technological interest. Nanoceria in pure and doped forms has current and potential use in solid oxide fuel cells, catalysis, UV-screening, chemical mechanical planarization, oxygen sensors, and bio-medical applications. The characteristic feature of Ce to switch between the +3 and +4 oxidation states renders oxygen buffering capability to ceria. The ease of this transformation was expected to be enhanced in the nanoceria. In most the practical scenarios, it is necessary to have a stable suspension of ceria nanoparticles (CNPs) over longer periods of time. However, the existing literature is confined to short term studies pertaining to synthesis and property evaluation. Having understood the need for a comprehensive understanding of the CNP suspensions, this dissertation is primarily aimed at understanding the behavior of CNPs in various chemical and physical environments. We have synthesized CNPs in the absence of any surfactants at room temperature and studied the aging characteristics. After gaining some understanding about the behavior of this functional oxide, the synthesis environment and aging temperature were varied, and their affects were carefully analyzed using various materials analysis techniques such as high resolution transmission electron microscopy (HRTEM), UV-Visible spectroscopy (UV-Vis), and X-ray photoelectron spectroscopy (XPS). When the CNPs were aged at room temperature in as-synthesized condition, they were observed to spontaneously assemble and evolve as fractal superoctahedral structures. The reasons for this unique polycrystalline morphology were attributed to the symmetry driven assembly of the individual truncated octahedral and octahedral seed of the ceria. HRTEM and Fast Fourier Transform (FFT) analyses were used to explain the agglomeration behavior and evolution of the octahedral morphology. Some of the observations were supported by

  2. Determinants of Bacterial Morphology: From Fundamentals to Possibilities for Antimicrobial Targeting

    Directory of Open Access Journals (Sweden)

    Muriel C. F. van Teeseling

    2017-07-01

    Full Text Available Bacterial morphology is extremely diverse. Specific shapes are the consequence of adaptive pressures optimizing bacterial fitness. Shape affects critical biological functions, including nutrient acquisition, motility, dispersion, stress resistance and interactions with other organisms. Although the characteristic shape of a bacterial species remains unchanged for vast numbers of generations, periodical variations occur throughout the cell (division and life cycles, and these variations can be influenced by environmental conditions. Bacterial morphology is ultimately dictated by the net-like peptidoglycan (PG sacculus. The species-specific shape of the PG sacculus at any time in the cell cycle is the product of multiple determinants. Some morphological determinants act as a cytoskeleton to guide biosynthetic complexes spatiotemporally, whereas others modify the PG sacculus after biosynthesis. Accumulating evidence supports critical roles of morphogenetic processes in bacteria-host interactions, including pathogenesis. Here, we review the molecular determinants underlying morphology, discuss the evidence linking bacterial morphology to niche adaptation and pathogenesis, and examine the potential of morphological determinants as antimicrobial targets.

  3. Nanoscale Morphology of Doctor Bladed versus Spin-Coated Organic Photovoltaic Films

    KAUST Repository

    Pokuri, Balaji Sesha Sarath

    2017-08-17

    Recent advances in efficiency of organic photovoltaics are driven by judicious selection of processing conditions that result in a “desired” morphology. An important theme of morphology research is quantifying the effect of processing conditions on morphology and relating it to device efficiency. State-of-the-art morphology quantification methods provide film-averaged or 2D-projected features that only indirectly correlate with performance, making causal reasoning nontrivial. Accessing the 3D distribution of material, however, provides a means of directly mapping processing to performance. In this paper, two recently developed techniques are integrated—reconstruction of 3D morphology and subsequent conversion into intuitive morphology descriptors —to comprehensively image and quantify morphology. These techniques are applied on films generated by doctor blading and spin coating, additionally investigating the effect of thermal annealing. It is found that morphology of all samples exhibits very high connectivity to electrodes. Not surprisingly, thermal annealing consistently increases the average domain size in the samples, aiding exciton generation. Furthermore, annealing also improves the balance of interfaces, enhancing exciton dissociation. A comparison of morphology descriptors impacting each stage of photophysics (exciton generation, dissociation, and charge transport) reveals that spin-annealed sample exhibits superior morphology-based performance indicators. This suggests substantial room for improvement of blade-based methods (process optimization) for morphology tuning to enhance performance of large area devices.

  4. Nanoscale strontium titanate photocatalysts for overall water splitting.

    Science.gov (United States)

    Townsend, Troy K; Browning, Nigel D; Osterloh, Frank E

    2012-08-28

    SrTiO(3) (STO) is a large band gap (3.2 eV) semiconductor that catalyzes the overall water splitting reaction under UV light irradiation in the presence of a NiO cocatalyst. As we show here, the reactivity persists in nanoscale particles of the material, although the process is less effective at the nanoscale. To reach these conclusions, Bulk STO, 30 ± 5 nm STO, and 6.5 ± 1 nm STO were synthesized by three different methods, their crystal structures verified with XRD and their morphology observed with HRTEM before and after NiO deposition. In connection with NiO, all samples split water into stoichiometric mixtures of H(2) and O(2), but the activity is decreasing from 28 μmol H(2) g(-1) h(-1) (bulk STO), to 19.4 μmol H(2) g(-1) h(-1) (30 nm STO), and 3.0 μmol H(2) g(-1) h(-1) (6.5 nm STO). The reasons for this decrease are an increase of the water oxidation overpotential for the smaller particles and reduced light absorption due to a quantum size effect. Overall, these findings establish the first nanoscale titanate photocatalyst for overall water splitting.

  5. Extrinsic morphology of graphene

    International Nuclear Information System (INIS)

    Li, Teng

    2011-01-01

    Graphene is intrinsically non-flat and corrugates randomly. Since the corrugating physics of atomically thin graphene is strongly tied to its electronics properties, randomly corrugating morphology of graphene poses a significant challenge to its application in nanoelectronic devices for which precise (digital) control is the key. Recent studies revealed that the morphology of substrate-supported graphene is regulated by the graphene–substrate interaction, thus is distinct from the random intrinsic morphology of freestanding graphene. The regulated extrinsic morphology of graphene sheds light on new pathways to fine tune the properties of graphene. To guide further research to explore these fertile opportunities, this paper reviews recent progress on modeling and experimental studies of the extrinsic morphology of graphene under a wide range of external regulation, including two-dimensional and one-dimensional substrate surface features and one-dimensional and zero-dimensional nanoscale scaffolds (e.g. nanowires and nanoparticles)

  6. High-speed nanoscale characterization of dewetting via dynamic transmission electron microscopy

    International Nuclear Information System (INIS)

    Hihath, Sahar; Santala, Melissa K.; Campbell, Geoffrey; Benthem, Klaus van

    2016-01-01

    The dewetting of thin films can occur in either the solid or the liquid state for which different mass transport mechanisms are expected to control morphological changes. Traditionally, dewetting dynamics have been examined on time scales between several seconds to hours, and length scales ranging between nanometers and millimeters. The determination of mass transport mechanisms on the nanoscale, however, requires nanoscale spatial resolution and much shorter time scales. This study reports the high-speed observation of dewetting phenomena for kinetically constrained Ni thin films on crystalline SrTiO_3 substrates. Movie-mode Dynamic Transmission Electron Microscopy (DTEM) was used for high-speed image acquisition during thin film dewetting at different temperatures. DTEM imaging confirmed that the initial stages of film agglomeration include edge retraction, hole formation, and growth. Finite element modeling was used to simulate temperature distributions within the DTEM samples after laser irradiation with different energies. For pulsed laser irradiation at 18 μJ, experimentally observed hole growth suggests that Marangoni flow dominates hole formation in the liquid nickel film. After irradiation with 13.8 μJ, however, the observations suggest that dewetting was initiated by nucleation of voids followed by hole growth through solid-state surface diffusion.

  7. High-speed nanoscale characterization of dewetting via dynamic transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hihath, Sahar [Department of Materials Science and Engineering, University of California, Davis, 1 Shields Ave., Davis, California 95616 (United States); Department of Physics, University of California, Davis, 1 Shields Ave., Davis, California 95616 (United States); Santala, Melissa K.; Campbell, Geoffrey [Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Benthem, Klaus van, E-mail: benthem@ucdavis.edu [Department of Materials Science and Engineering, University of California, Davis, 1 Shields Ave., Davis, California 95616 (United States)

    2016-08-28

    The dewetting of thin films can occur in either the solid or the liquid state for which different mass transport mechanisms are expected to control morphological changes. Traditionally, dewetting dynamics have been examined on time scales between several seconds to hours, and length scales ranging between nanometers and millimeters. The determination of mass transport mechanisms on the nanoscale, however, requires nanoscale spatial resolution and much shorter time scales. This study reports the high-speed observation of dewetting phenomena for kinetically constrained Ni thin films on crystalline SrTiO{sub 3} substrates. Movie-mode Dynamic Transmission Electron Microscopy (DTEM) was used for high-speed image acquisition during thin film dewetting at different temperatures. DTEM imaging confirmed that the initial stages of film agglomeration include edge retraction, hole formation, and growth. Finite element modeling was used to simulate temperature distributions within the DTEM samples after laser irradiation with different energies. For pulsed laser irradiation at 18 μJ, experimentally observed hole growth suggests that Marangoni flow dominates hole formation in the liquid nickel film. After irradiation with 13.8 μJ, however, the observations suggest that dewetting was initiated by nucleation of voids followed by hole growth through solid-state surface diffusion.

  8. Nanoscale Chemical Processes Affecting Storage Capacities and Seals during Geologic CO2 Sequestration.

    Science.gov (United States)

    Jun, Young-Shin; Zhang, Lijie; Min, Yujia; Li, Qingyun

    2017-07-18

    Geologic CO 2 sequestration (GCS) is a promising strategy to mitigate anthropogenic CO 2 emission to the atmosphere. Suitable geologic storage sites should have a porous reservoir rock zone where injected CO 2 can displace brine and be stored in pores, and an impermeable zone on top of reservoir rocks to hinder upward movement of buoyant CO 2 . The injection wells (steel casings encased in concrete) pass through these geologic zones and lead CO 2 to the desired zones. In subsurface environments, CO 2 is reactive as both a supercritical (sc) phase and aqueous (aq) species. Its nanoscale chemical reactions with geomedia and wellbores are closely related to the safety and efficiency of CO 2 storage. For example, the injection pressure is determined by the wettability and permeability of geomedia, which can be sensitive to nanoscale mineral-fluid interactions; the sealing safety of the injection sites is affected by the opening and closing of fractures in caprocks and the alteration of wellbore integrity caused by nanoscale chemical reactions; and the time scale for CO 2 mineralization is also largely dependent on the chemical reactivities of the reservoir rocks. Therefore, nanoscale chemical processes can influence the hydrogeological and mechanical properties of geomedia, such as their wettability, permeability, mechanical strength, and fracturing. This Account reviews our group's work on nanoscale chemical reactions and their qualitative impacts on seal integrity and storage capacity at GCS sites from four points of view. First, studies on dissolution of feldspar, an important reservoir rock constituent, and subsequent secondary mineral precipitation are discussed, focusing on the effects of feldspar crystallography, cations, and sulfate anions. Second, interfacial reactions between caprock and brine are introduced using model clay minerals, with focuses on the effects of water chemistries (salinity and organic ligands) and water content on mineral dissolution and

  9. Nanoscale ferroelectrics and multiferroics key processes and characterization issues, and nanoscale effects

    CERN Document Server

    Alguero, Miguel

    2016-01-01

    This book reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, it covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. The book is developed from t...

  10. Engineering Platinum Alloy Electrocatalysts in Nanoscale for PEMFC Application

    Energy Technology Data Exchange (ETDEWEB)

    He, Ting [Idaho National Laboratory

    2016-03-01

    Fuel cells are expected to be a key next-generation energy source used for vehicles and homes, offering high energy conversion efficiency and minimal pollutant emissions. However, due to large overpotentials on anode and cathode, the efficiency is still much lower than theoretically predicted. During the past decades, considerable efforts have been made to investigate synergy effect of platinum alloyed with base metals. But, engineering the alloy particles in nanoscale has been a challenge. Most important challenges in developing nanostructured materials are the abilities to control size, monodispersity, microcomposition, and even morphology or self-assembly capability, so called Nanomaterials-by-Design, which requires interdisciplinary collaborations among computational modeling, chemical synthesis, nanoscale characterization as well as manufacturing processing. Electrocatalysts, particularly fuel cell catalysts, are dramatically different from heterogeneous catalysts because the surface area in micropores cannot be electrochemically controlled on the same time scale as more transport accessible surfaces. Therefore, electrocatalytic architectures need minimal microporous surface area while maximizing surfaces accessible through mesopores or macropores, and to "pin" the most active, highest performance physicochemical state of the materials even when exposed to thermodynamic forces, which would otherwise drive restructuring, crystallization, or densification of the nanoscale materials. In this presentation, results of engineering nanoscale platinum alloy particles down to 2 ~ 4 nm will be discussed. Based on nature of alloyed base metals, various synthesis technologies have been studied and developed to achieve capabilities of controlling particle size and particle microcomposition, namely, core-shell synthesis, microemulsion technique, thermal decomposition process, surface organometallic chemical method, etc. The results show that by careful engineering the

  11. Probing polymer nanocomposite morphology by small angle ...

    Indian Academy of Sciences (India)

    Polyamide nanocomposite films were prepared from nanometer-sized silica particles having particle radius of gyration (g) of about 66 Å and trimesoyl chloride--phenylene diamine-based polyamides having macromolecular units of about 100-140 Å. The nanoscale morphology of the samples was characterized using ...

  12. Neuromorphic computing with nanoscale spintronic oscillators.

    Science.gov (United States)

    Torrejon, Jacob; Riou, Mathieu; Araujo, Flavio Abreu; Tsunegi, Sumito; Khalsa, Guru; Querlioz, Damien; Bortolotti, Paolo; Cros, Vincent; Yakushiji, Kay; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, Mark D; Grollier, Julie

    2017-07-26

    Neurons in the brain behave as nonlinear oscillators, which develop rhythmic activity and interact to process information. Taking inspiration from this behaviour to realize high-density, low-power neuromorphic computing will require very large numbers of nanoscale nonlinear oscillators. A simple estimation indicates that to fit 10 8 oscillators organized in a two-dimensional array inside a chip the size of a thumb, the lateral dimension of each oscillator must be smaller than one micrometre. However, nanoscale devices tend to be noisy and to lack the stability that is required to process data in a reliable way. For this reason, despite multiple theoretical proposals and several candidates, including memristive and superconducting oscillators, a proof of concept of neuromorphic computing using nanoscale oscillators has yet to be demonstrated. Here we show experimentally that a nanoscale spintronic oscillator (a magnetic tunnel junction) can be used to achieve spoken-digit recognition with an accuracy similar to that of state-of-the-art neural networks. We also determine the regime of magnetization dynamics that leads to the greatest performance. These results, combined with the ability of the spintronic oscillators to interact with each other, and their long lifetime and low energy consumption, open up a path to fast, parallel, on-chip computation based on networks of oscillators.

  13. Determining the morphology of polystyrene-block-poly(2-vinylpyridine) micellar reactors for ZnO nanoparticle synthesis.

    Science.gov (United States)

    El-Atwani, Osman; El-Atwani, Osman C; Aytun, Taner; Mutaf, Omer Faruk; Srot, Vesna; van Aken, Peter A; Ow-Yang, Cleva W

    2010-05-18

    We report the use of reverse PS-b-P2VP diblock copolymer micelles as true nanoscale-sized reactor vessels to synthesize ZnO nanoparticles. The reverse micelles were formed in toluene and then sequentially loaded with zinc acetate dihydrate and tetramethylammonium hydroxide reactants. Moreover, high spatial resolution Z-contrast imaging and EDX spectroscopy techniques were used to confirm the segregation of the Zn cation to the core of the loaded micelles. Determining the chemical distribution with high nanoscale spatial resolution is shown to complement the less direct characterization by AFM, DLS and FTIR, thus demonstrating broader implications for the characterization of hybrid nanocomposite systems.

  14. Ag films deposited on Si and Ti: How the film-substrate interaction influences the nanoscale film morphology

    Science.gov (United States)

    Ruffino, F.; Torrisi, V.

    2017-11-01

    Submicron-thick Ag films were sputter deposited, at room temperature, on Si, covered by the native SiO2 layer, and on Ti, covered by the native TiO2 layer, under normal and oblique deposition angle. The aim of this work was to study the morphological differences in the grown Ag films on the two substrates when fixed all the other deposition parameters. In fact, the surface diffusivity of the Ag adatoms is different on the two substrates (higher on the SiO2 surface) due to the different Ag-SiO2 and Ag-TiO2 atomic interactions. So, the effect of the adatoms surface diffusivity, as determined by the adatoms-substrate interaction, on the final film morphology was analyzed. To this end, microscopic analyses were used to study the morphology of the grown Ag films. Even if the homologous temperature prescribes that the Ag film grows on both substrates in the zone I described by the structure zone model some significant differences are observed on the basis of the supporting substrate. In the normal incidence condition, on the SiO2/Si surface a dense close-packed Ag film exhibiting a smooth surface is obtained, while on the TiO2/Ti surface a more columnar film morphology is formed. In the oblique incidence condition the columnar morphology for the Ag film occurs both on SiO2/Si and TiO2/Ti but a higher porous columnar film is obtained on TiO2/Ti due to the lower Ag diffusivity. These results indicate that the adatoms diffusivity on the substrate as determined by the adatom-surface interaction (in addition to the substrate temperature) strongly determines the final film nanostructure.

  15. Monolithic integration of nanoscale tensile specimens and MEMS structures

    International Nuclear Information System (INIS)

    Yilmaz, Mehmet; Kysar, Jeffrey W

    2013-01-01

    Nanoscale materials often have stochastic material properties due to a random distribution of material defects and an insufficient number of defects to ensure a consistent average mechanical response. Current methods to measure the mechanical properties employ MEMS-based actuators. The nanoscale specimens are typically mounted manually onto the load platform, so the boundary conditions have random variations, complicating the experimental measurement of the intrinsic stochasticity of the material properties. Here we show methods for monolithic integration of a nanoscale specimen co-fabricated with the loading platform. The nanoscale specimen is gold with dimensions of ∼40 nm thickness, 350 ± 50 nm width, and 7 μm length and the loading platform is an interdigitated electrode electrostatic actuator. The experiment is performed in a scanning electron microscope and digital image correlation is employed to measure displacements to determine stress and strain. The ultimate tensile strength of the nanocrystalline nanoscale specimen approaches 1 GPa, consistent with measurements made by other nanometer scale sample characterization methods on other material samples at the nanometer scale, as well as gold samples at the nanometer scale. The batch-compatible microfabrication method can be used to create nominally identical nanoscale specimens and boundary conditions for a broad range of materials. (paper)

  16. Nanoscale Morphology of Doctor Bladed versus Spin-Coated Organic Photovoltaic Films

    KAUST Repository

    Pokuri, Balaji Sesha Sarath; Sit, Joseph; Wodo, Olga; Baran, Derya; Ameri, Tayebeh; Brabec, Christoph J.; Moule, Adam J.; Ganapathysubramanian, Baskar

    2017-01-01

    Recent advances in efficiency of organic photovoltaics are driven by judicious selection of processing conditions that result in a “desired” morphology. An important theme of morphology research is quantifying the effect of processing conditions

  17. Laser ablation of nanoscale particles with 193 nm light

    International Nuclear Information System (INIS)

    Choi, J H; Lucas, D; Koshland, C P

    2007-01-01

    Laser interaction with nanoscale particles is distinct and different from laser-bulk material interaction, where a hot plasma is normally created. Here, we review our studies on 193 nm laser ablation of various nanoscale particles including NaCl, soot, polystyrene, and gold. The 20 ns laser beam with fluences up to 0.3 J/cm 2 irradiates nanoparticles in a gas stream at laser repetition rates from 10 to 100 Hz. The particle size distributions before and after irradiation are measured with a scanning mobility particle sizer (SMPS), and particle morphology is examined with electron microscopy. All the nanomaterials studied exhibit a similar disintegration pattern and similar particle formation characteristics. No broadband emission associated with particle heating or optical breakdown is observed. The nanoparticles formed after irradiation have a smaller mean diameter and an order of magnitude higher number concentration with a more spherical shape compared to the original particles. We use the photon-atom ratio (PAR) to interpret the laser-particle interaction energetics

  18. Dynamics at the nanoscale

    International Nuclear Information System (INIS)

    Stoneham, A.M.; Gavartin, J.L.

    2007-01-01

    However fascinating structures may be at the nanoscale, time-dependent behaviour at the nanoscale has far greater importance. Some of the dynamics is random, with fluctuations controlling rate processes and making thermal ratchets possible. Some of the dynamics causes the transfer of energy, of signals, or of charge. Such transfers are especially efficiently controlled in biological systems. Other dynamical processes occur when we wish to control the nanoscale, e.g., to avoid local failures of gate dielectrics, or to manipulate structures by electronic excitation, to use spin manipulation in quantum information processing. Our prime purpose is to make clear the enormous range and variety of time-dependent nanoscale phenomena

  19. Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dapeng; Poudyal, Narayan; Rong, Chuanbing [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Zhang Ying [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Kramer, M.J. [Materials Science and Engineering, Ames Laboratory, USDOE, Iowa State University, Ames, IA 50011 (United States); Liu, J. Ping, E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2012-09-15

    Nanoscale hybrid magnets containing SmCo{sub 5} and Nd{sub 2}Fe{sub 14}B hard magnetic phases have been produced via a novel 'in-one-pot' processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybrid magnets have greatly improved thermal stability compared to the Nd{sub 2}Fe{sub 14}B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo{sub 5} counterpart. - Highlights: Black-Right-Pointing-Pointer We realize interphase exchange coupling in nanoscale SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B magnets. Black-Right-Pointing-Pointer We observe homogenously distributed two-phase grains with size smaller than 20 nm. Black-Right-Pointing-Pointer We observe a common Curie temperature in the hybrid magnet. Black-Right-Pointing-Pointer High-temperature magnetic properties of the hybrid magnets greatly improved. Black-Right-Pointing-Pointer Plastic deformation of composite materials leads to self-nanoscaling of grains.

  20. Fabrication of nanoscale speckle using broad ion beam milling on polymers for deformation analysis

    Directory of Open Access Journals (Sweden)

    Qinghua Wang

    2016-07-01

    Full Text Available We first report a fabrication technique of nanoscale speckle patterns on polymers using broad ion beam milling. The proposed technique is simple and low-cost to produce speckles ranging from dozens of nanometers to less than three micrometers in a large area of several millimeters. Random patterns were successfully produced with an argon (Ar ion beam on the surfaces of four kinds of polymers: the epoxy matrix of carbon fiber reinforced plastic, polyester, polyvinyl formal-acetal, and polyimide. The speckle morphologies slightly vary with different polymers. The fabricated speckle patterns have good time stability and are promising to be used to measure the nanoscale deformations of polymers using the digital image correlation method.

  1. Charge separation at nanoscale interfaces: energy-level alignment including two-quasiparticle interactions.

    Science.gov (United States)

    Li, Huashan; Lin, Zhibin; Lusk, Mark T; Wu, Zhigang

    2014-10-21

    The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

  2. Scanning nanoscale multiprobes for conductivity measurements

    DEFF Research Database (Denmark)

    Bøggild, Peter; Hansen, Torben Mikael; Kuhn, Oliver

    2000-01-01

    We report fabrication and measurements with two- and four-point probes with nanoscale dimensions, for high spatial resolution conductivity measurements on surfaces and thin films. By combination of conventional microfabrication and additive three-dimensional nanolithography, we have obtained...... electrode spacings down to 200 nm. At the tips of four silicon oxide microcantilevers, narrow carbon tips are grown in converging directions and subsequently coated with a conducting layer. The probe is placed in contact with a conducting surface, whereby the electrode resistance can be determined....... The nanoelectrodes withstand considerable contact force before breaking. The probe offers a unique possibility to position the voltage sensors, as well as the source and drain electrodes in areas of nanoscale dimensions. ©2000 American Institute of Physics....

  3. Rocket Science at the Nanoscale.

    Science.gov (United States)

    Li, Jinxing; Rozen, Isaac; Wang, Joseph

    2016-06-28

    Autonomous propulsion at the nanoscale represents one of the most challenging and demanding goals in nanotechnology. Over the past decade, numerous important advances in nanotechnology and material science have contributed to the creation of powerful self-propelled micro/nanomotors. In particular, micro- and nanoscale rockets (MNRs) offer impressive capabilities, including remarkable speeds, large cargo-towing forces, precise motion controls, and dynamic self-assembly, which have paved the way for designing multifunctional and intelligent nanoscale machines. These multipurpose nanoscale shuttles can propel and function in complex real-life media, actively transporting and releasing therapeutic payloads and remediation agents for diverse biomedical and environmental applications. This review discusses the challenges of designing efficient MNRs and presents an overview of their propulsion behavior, fabrication methods, potential rocket fuels, navigation strategies, practical applications, and the future prospects of rocket science and technology at the nanoscale.

  4. SEM method for direct visual tracking of nanoscale morphological changes of platinum based electrocatalysts on fixed locations upon electrochemical or thermal treatments

    Energy Technology Data Exchange (ETDEWEB)

    Zorko, Milena [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Jozinović, Barbara [Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Bele, Marjan [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Hodnik, Nejc, E-mail: nejc.hodnik@ki.si [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Gaberšček, Miran [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia)

    2014-05-01

    A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60 °C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas. - Highlights: • A new SEM method for observations of identical locations. • Nanoscale morphological consecutive changes on identical locations. • Electrochemical and thermal treatments on platinum based nanoparticles. • Potential cycling induces platinum dissolution with redeposition on top of the film. • At 1.4 V vs. RHE and 60 °C carbon corrosion and particle aggregation is observed.

  5. Impact of nanoscale topography on genomics and proteomics of adherent bacteria.

    Science.gov (United States)

    Rizzello, Loris; Sorce, Barbara; Sabella, Stefania; Vecchio, Giuseppe; Galeone, Antonio; Brunetti, Virgilio; Cingolani, Roberto; Pompa, Pier Paolo

    2011-03-22

    Bacterial adhesion onto inorganic/nanoengineered surfaces is a key issue in biotechnology and medicine, because it is one of the first necessary steps to determine a general pathogenic event. Understanding the molecular mechanisms of bacteria-surface interaction represents a milestone for planning a new generation of devices with unanimously certified antibacterial characteristics. Here, we show how highly controlled nanostructured substrates impact the bacterial behavior in terms of morphological, genomic, and proteomic response. We observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) that type-1 fimbriae typically disappear in Escherichia coli adherent onto nanostructured substrates, as opposed to bacteria onto reference glass or flat gold surfaces. A genetic variation of the fimbrial operon regulation was consistently identified by real time qPCR in bacteria interacting with the nanorough substrates. To gain a deeper insight into the molecular basis of the interaction mechanisms, we explored the entire proteomic profile of E. coli by 2D-DIGE, finding significant changes in the bacteria adherent onto the nanorough substrates, such as regulations of proteins involved in stress processes and defense mechanisms. We thus demonstrated that a pure physical stimulus, that is, a nanoscale variation of surface topography, may play per se a significant role in determining the morphological, genetic, and proteomic profile of bacteria. These data suggest that in depth investigations of the molecular processes of microorganisms adhering to surfaces are of great importance for the design of innovative biomaterials with active biological functionalities.

  6. Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Alexander M. Haruk

    2015-06-01

    Full Text Available Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design.

  7. Quantification of metallic nanoparticle morphology with tilt series imaging by transmission electron microscopy

    Science.gov (United States)

    Dutta, Aniruddha; Yuan, Biao; Clukay, Christopher J.; Grabill, Christopher N.; Heinrich, Helge; Bhattacharya, Aniket; Kuebler, Stephen M.

    2012-02-01

    We report on the quantitative analysis of electrolessly deposited Au and Ag nanoparticles (NPs) on SU8 polymer with the help of High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) in tilt series. Au NPs act as nucleating agents for the electroless deposition of silver. Au NPs were prepared by attachingAu^3+cations to amine functionalized SU8 polymeric surfaces and then reducing it with aqueous NaBH4. The nanoscale morphology of the deposited NPs on the surface of polymer has been studied from the dark field TEM cross sectional images. Ag NPs were deposited on the cross-linked polymeric surface from a silver citrate solution reduced by hydroquinone. HAADF-STEM enables us to determine the distances between the NPs and their exact locations at and near the surface. The particle distribution, sizes and densities provide us with the data necessary to control the parameters for the development of the electroless deposition technique for emerging nanoscale technologies.

  8. Nanoscale Ionic Liquids

    Science.gov (United States)

    2006-11-01

    Technical Report 11 December 2005 - 30 November 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanoscale Ionic Liquids 5b. GRANT NUMBER FA9550-06-1-0012...Title: Nanoscale Ionic Liquids Principal Investigator: Emmanuel P. Giannelis Address: Materials Science and Engineering, Bard Hall, Cornell University...based fluids exhibit high ionic conductivity. The NFs are typically synthesized by grafting a charged, oligomeric corona onto the nanoparticle cores

  9. A luminescent ratiometric pH sensor based on a nanoscale and biocompatible Eu/Tb-mixed MOF.

    Science.gov (United States)

    Xia, Tifeng; Zhu, Fengliang; Jiang, Ke; Cui, Yuanjing; Yang, Yu; Qian, Guodong

    2017-06-13

    The precise and real-time monitoring of localized pH changes is of great importance in many engineering and environmental fields, especially for monitoring small pH changes in biological environments and living cells. Metal-organic frameworks (MOFs) with their nanoscale processability show very promising applications in bioimaging and biomonitoring, but the fabrication of nanoscale MOFs is still a challenge. In this study, we synthesized a nanoscale mixed-lanthanide metal-organic framework by a microemulsion method. The morphology and size of the NMOF can be simply adjusted by the addition of different amounts of the CTAB surfactant. This NMOF exhibits significant pH-dependent luminescence emission, which can act as a self-referenced pH sensor based on two emissions of Tb 3+ at 545 nm and Eu 3+ at 618 nm in the pH range from 3.00 to 7.00. The MTT assay and optical microscopy assay demonstrate the low cytotoxicity and good biocompatibility of the nanosensor.

  10. Determination of nanoscale particles in the air of working zone at the metallurgical production

    Directory of Open Access Journals (Sweden)

    Т.S. Ulanova

    2015-03-01

    Full Text Available The results of studies of the air of working zone at the metallurgical production on the example of Avisma OJSC (Berezniki, the Perm Territory for the content of nanoscale particles are specified. The maximum nanoparticles concentration in the range of 13523–28609 mln./m3 is determined at the working place of the titanium production smelter with the maximum size of particles of 10–15 nm. At the working place in the administrative building (reference working place the maximum concentration is determined within the range of 524–1000 mln./m3; the maximum size of nanoparticles is 20 nm. It was established that the number concentration of nanoparticles at the reference working places (administration of Avisma OJSC is significantly lower than at the working places of main production processes. The presented studies can be used as the additional factors in the assessment of labor conditions and occupational risk during the manufacture and use of materials containing nanoparticles as well as the production processes with the nanoparticles formation.

  11. Friction laws at the nanoscale.

    Science.gov (United States)

    Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

    2009-02-26

    Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

  12. In-situ Neutron Scattering Determination of 3D Phase-Morphology Correlations in Fullerene Block Copolymer Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Alamgir [Univ. of Akron, OH (United States); Bucknall, David [Georgia Inst. of Technology, Atlanta, GA (United States); Raghavan, Dharmaraj [Howard Univ., Washington, DC (United States)

    2015-02-23

    a fundamental study that does not set out to evaluate new materials or produce devices, but rather we wish to understand from first principles how the molecular structure of polymer-fullerene mixtures determined using neutron scattering (small angle neutron scattering and neutron reflection) affects device characteristics and consequently performance. While this seems a very obvious question to ask, this critical understanding is far from being realized despite the wealth of studies into OPV’s and is severely limiting organic PV devices from achieving their theoretical potential. Despite the fundamental nature of proposed work, it is essential to remain technologically relevant and therefore to ensure we address these issues we have developed relationships on the fundamental nature of structure-processing-property paradigm as applied to future need for large area, flexible OPV devices. Nanoscale heterojunction systems consisting of fullerenes dispersed in conjugated polymers are promising materials candidates for achieving high performance organic photovoltaic (OPV) devices. In order to understand the phase behavior in these devices, neutron reflection is used to determine the behavior of model conjugated polymer-fullerene mixtures. Neutron reflection is particularly useful for these types of thin film studies since the fullerene generally have a high scattering contrast with respect to most polymers. We are studying model bulk heterojunction (BHJ) films based on mixtures of poly(3-hexyl thiophene)s (P3HT), a widely used photoconductive polymer, and different fullerenes (C60, PCBM and bis-PCBM). The characterization technique of neutron reflectivity measurements have been used to determine film morphology in a direction normal to the film surfaces. The novelty of the approach over previous studies is that the BHJ layer is sandwiched between a PEDOT/PSS and Al layers in real device configuration. Using this model system, the effect of typical thermal annealing

  13. The Morphology of Silver Layers on SU8 polymers prepared by Electroless Deposition

    Science.gov (United States)

    Dutta, Aniruddha; Yuan, Biao; Heinrich, Helge; Grabill, Chris; Williams, Henry; Kuebler, Stephen; Bhattacharya, Aniket

    2010-03-01

    Silver was deposited onto the functionalized surface of polymeric SU-8 where gold nanoparticles (Au-NPs) act as nucleation sites using electroless metallization chemistry. Here we report on the evolution of the nanoscale morphology of deposited Ag studied by Transmission Electron Microscopy (TEM). In TEM of sample cross sections correlations between the original gold and the silver nanoparticles were obtained while plan-view TEM results showed the distribution of nanoparticles on the surface. Scanning TEM with a high-angle annular dark field detector was used to obtain atomic number contrast. The morphology of the deposited Ag was controlled through the presence and absence of gum Arabic. The thickness and height fluctuations of the Ag layer were determined as a function of time and a statistical analysis of the growth process was conducted for the initial deposition periods.

  14. Symposium GC: Nanoscale Charge Transport in Excitonic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bommisetty, Venkat [Univ. of South Dakota, Vermillion, SD (United States)

    2011-06-23

    This paper provides a summary only and table of contents of the sessions. Excitonic solar cells, including all-organic, hybrid organic-inorganic and dye-sensitized solar cells (DSSCs), offer strong potential for inexpensive and large-area solar energy conversion. Unlike traditional inorganic semiconductor solar cells, where all the charge generation and collection processes are well understood, these excitonic solar cells contain extremely disordered structures with complex interfaces which results in large variations in nanoscale electronic properties and has a strong influence on carrier generation, transport, dissociation and collection. Detailed understanding of these processes is important for fabrication of highly efficient solar cells. Efforts to improve efficiency are underway at a large number of research groups throughout the world focused on inorganic and organic semiconductors, photonics, photophysics, charge transport, nanoscience, ultrafast spectroscopy, photonics, semiconductor processing, device physics, device structures, interface structure etc. Rapid progress in this multidisciplinary area requires strong synergetic efforts among researchers from diverse backgrounds. Such effort can lead to novel methods for development of new materials with improved photon harvesting and interfacial treatments for improved carrier transport, process optimization to yield ordered nanoscale morphologies with well defined electronic structures.

  15. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    KAUST Repository

    Sibillano, T.

    2014-11-10

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes\\' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  16. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    KAUST Repository

    Sibillano, T.; De Caro, L.; Altamura, D.; Siliqi, D.; Ramella, M.; Boccafoschi, F.; Ciasca, G.; Campi, G.; Tirinato, Luca; Di Fabrizio, Enzo M.; Giannini, C.

    2014-01-01

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  17. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    Science.gov (United States)

    Sibillano, T.; de Caro, L.; Altamura, D.; Siliqi, D.; Ramella, M.; Boccafoschi, F.; Ciasca, G.; Campi, G.; Tirinato, L.; di Fabrizio, E.; Giannini, C.

    2014-11-01

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  18. Effect of aging of V{sub 2}O{sub 5} sol on properties of nanoscale films

    Energy Technology Data Exchange (ETDEWEB)

    Senapati, Sujata [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Samtel Centre for Display Technologies, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Panda, Siddhartha, E-mail: spanda@iitk.ac.in [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Samtel Centre for Display Technologies, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2016-01-29

    Nanoscale films having thicknesses in the range of 92 nm–137 nm were obtained by spin coating V{sub 2}O{sub 5} sol at different stages of aging. The observed structural and morphological changes with time can be attributed to the reactions occurring in the sol. The film morphology changed from an indistinctive featureless film to a homogenous film having ribbon-like nanostructures with aging of sols. TGA and FTIR analysis confirmed loss in the amount of intercalated water content with aging giving rise to structural changes (decrease in interlayer spacing) which were observed using XRD. Variations in mechanical, electrical, and optical properties of the thin films were observed with aging of the sol. Strain in the films were found to decrease with aging. The electrical conductivity increased with aging and this can be correlated to the improved crystallinity of the films with aging. The optical bandgap (calculated from UV–Vis data) decreased and the transmittance increased with aging. - Highlights: • Nanoscale V{sub 2}O{sub 5} films synthesized by spin coating progressively aged sol. • Structural and morphological changes were observed in the films. • Loss of water of hydration resulted in decrease in interlayer spacing. • Strain in the film decreased and conductivity increased with aging. • Increase in transmittance and decrease in optical band gap with aging observed.

  19. Controlling Film Morphology in Conjugated Polymer

    Science.gov (United States)

    Park, Lee Y.; Munro, Andrea M.; Ginger, David S.

    2009-01-01

    We study the effects of patterned surface chemistry on the microscale and nanoscale morphology of solution-processed donor/acceptor polymer-blend films. Focusing on combinations of interest in polymer solar cells, we demonstrate that patterned surface chemistry can be used to tailor the film morphology of blends of semiconducting polymers such as poly-[2-(3,7-dimethyloctyloxy)-5-methoxy-p-phenylenevinylene] (MDMO-PPV), poly-3-hexylthiophene (P3HT), poly[(9,9-dioctylflorenyl-2,7-diyl)-co-benzothiadiazole)] (F8BT), and poly(9,9-dioctylfluorene-co-bis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-1,4-phenylendiamine) (PFB) with the fullerene derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We present a method for generating patterned, fullerene-terminated monolayers on gold surfaces, and use microcontact printing and Dip-Pen Nanolithography (DPN) to pattern alkanethiols with both micro- and nanoscale features. After patterning with fullerenes and other functional groups, we backfill the rest of the surface with a variety of thiols to prepare substrates with periodic variations in surface chemistry. Spin coating polymer:PCBM films onto these substrates, followed by thermal annealing under nitrogen, leads to the formation of structured polymer films. We characterize these films with Atomic Force Microscopy (AFM), Raman spectroscopy, and fluorescence microscopy. The surface patterns are effective in guiding phase separation in all of the polymer:PCBM systems investigated, and lead to a rich variety of film morphologies that are inaccessible with unpatterned substrates. We demonstrate our ability to guide pattern formation in films thick enough of be of interest for actual device applications (up to 200 nm in thickness) using feature sizes as small as 100 nm. Finally, we show that the surface chemistry can lead to variations in film morphology on length scales significantly smaller than those used in generating the original surface patterns. The variety of

  20. Nanoscale examination of microdamage in sheep cortical bone using synchrotron radiation transmission x-ray microscopy.

    Directory of Open Access Journals (Sweden)

    Garry R Brock

    Full Text Available Microdamage occurs in bone through repeated and excessive loading. Accumulation of microdamage weakens bone, leading to a loss of strength, stiffness and energy dissipation in the tissue. Imaging techniques used to examine microdamage have typically been limited to the microscale. In the current study microdamage was examined at the nanoscale using transmission x-ray microscopy with an x-ray negative stain, lead-uranyl acetate. Microdamage was generated in notched and unnotched beams of sheep cortical bone (2×2×20 mm, with monotonic and fatigue loading. Bulk sections were removed from beams and stained with lead-uranyl acetate to identify microdamage. Samples were sectioned to 50 microns and imaged using transmission x-ray microscopy producing projection images of microdamage with nanoscale resolution. Staining indicated microdamage occurred in both the tensile and compressive regions. A comparison between monotonic and fatigue loading indicated a statistically significant greater amount of stain present in fatigue loaded sections. Microdamage occurred in three forms: staining to existing bone structures, cross hatch damage and a single crack extending from the notch tip. Comparison to microcomputed tomography demonstrated differences in damage morphology and total damage between the microscale and nanoscale. This method has future applications for understanding the underlying mechanisms for microdamage formation as well as three-dimensional nanoscale examination of microdamage.

  1. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  2. Crystal morphology variation in inkjet-printed organic materials

    Science.gov (United States)

    Ihnen, Andrew C.; Petrock, Anne M.; Chou, Tsengming; Samuels, Phillip J.; Fuchs, Brian E.; Lee, Woo Y.

    2011-11-01

    The recent commercialization of piezoelectric-based drop-on-demand inkjet printers provides an additive processing platform for producing and micropatterning organic crystal structures. We report an inkjet printing approach where macro- and nano-scale energetic composites composed of cyclotrimethylenetrinitramine (RDX) crystals dispersed in a cellulose acetate butyrate (CAB) matrix are produced by direct phase transformation from organic solvent-based all-liquid inks. The characterization of printed composites illustrates distinct morphological changes dependent on ink deposition parameters. When 10 pL ink droplets rapidly formed a liquid pool, a coffee ring structure containing dendritic RDX crystals was produced. By increasing the substrate temperature, and consequently the evaporation rate of the pooled ink, the coffee ring structure was mitigated and shorter dendrites from up to ∼1 to 0.2 mm with closer arm spacing from ∼15 to 1 μm were produced. When the nucleation and growth of RDX and CAB were confined within the evaporating droplets, a granular structure containing nanoscale RDX crystals was produced. The results suggest that evaporation rate and microfluidic droplet confinement can effectively be used to tailor the morphology of inkjet-printed energetic composites.

  3. Surface profile gradient in amorphous Ta{sub 2}O{sub 5} semi conductive layers regulates nanoscale electric current stability

    Energy Technology Data Exchange (ETDEWEB)

    Cefalas, A.C., E-mail: ccefalas@eie.gr [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Kollia, Z.; Spyropoulos-Antonakakis, N.; Gavriil, V. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Christofilos, D.; Kourouklis, G. [Physics Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Semashko, V.V.; Pavlov, V. [Kazan Federal University, Institute of Physics, 18 Kremljovskaja str., Kazan 420008 (Russian Federation); Sarantopoulou, E. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece); Kazan Federal University, Institute of Physics, 18 Kremljovskaja str., Kazan 420008 (Russian Federation)

    2017-02-28

    Highlights: • The work links the surface morphology of amorphous semiconductors with both their electric-thermal properties and current stability at the nanoscale (<1 μm). • Measured high correlation value between surface morphological spatial gradient and conductive electron energy spatial gradient or thermal gradient. • Unidirectional current stability is associated with asymmetric nanodomains along nanosize conductive paths. • Bidirectional current stability is inherent with either long conductive paths or nanosize conductive paths along symmetric nanodomains. • Conclusion: Surface design improves current stability across nanoelectonic junctions. - Abstract: A link between the morphological characteristics and the electric properties of amorphous layers is established by means of atomic, conductive, electrostatic force and thermal scanning microscopy. Using amorphous Ta{sub 2}O{sub 5} (a-Ta{sub 2}O{sub 5}) semiconductive layer, it is found that surface profile gradients (morphological gradient), are highly correlated to both the electron energy gradient of trapped electrons in interactive Coulombic sites and the thermal gradient along conductive paths and thus thermal and electric properties are correlated with surface morphology at the nanoscale. Furthermore, morphological and electron energy gradients along opposite conductive paths of electrons intrinsically impose a current stability anisotropy. For either long conductive paths (L > 1 μm) or along symmetric nanodomains, current stability for both positive and negative currents i is demonstrated. On the contrary, for short conductive paths along non-symmetric nanodomains, the set of independent variables (L, i) is spanned by two current stability/intability loci. One locus specifies a stable state for negative currents, while the other locus also describes a stable state for positive currents.

  4. Tuning ligament shape in dealloyed nanoporous tin and the impact of nanoscale morphology on its applications in Na-ion alloy battery anodes

    Science.gov (United States)

    Detsi, Eric; Petrissans, Xavier; Yan, Yan; Cook, John B.; Deng, Ziling; Liang, Yu-Lun; Dunn, Bruce; Tolbert, Sarah H.

    2018-05-01

    Control over the morphology of nanostructured materials is of primary importance in structure-property relationship studies. Although the size of ligaments and pores in dealloyed nanoporous metals can be controlled by thermal and/or (electro)chemical treatments, tuning the shape of those ligaments is much harder. In the present work, we use corroding media with different reactivity to effectively tailor the ligament shape in nanoporous tin (NP-Sn) during dealloying by free corrosion. NP-Sn architectures with nanowire and granular ligament shapes were made by controlling the pH of the corroding solution, and thus the rate of Sn oxidation relative to the etching rate of the sacrificial component. The standard nanowire structure was formed under acidic conditions where oxidation was slow, but a hierarchical granular structure was formed when fusion of the Sn nanocrystals was inhibited by surface oxidation. To demonstrate the advantages of this architectural control, these two materials systems were investigated as electrodes for Na-ion battery anodes. Similar initial Na storage capacities of ˜500 and 550 mAh/g were achieved in the nanowire and granular materials, respectively, but the cycle life of the two materials was quite different. NP-Sn with a granular ligament shape showed enhanced stability with a capacity retention of ˜55 % over 95 cycles at a specific current of 40 mA/g. By contrast, NP-Sn with a nanowire ligament shape showed very fast capacity fading within the first 10 cycles. This work thus demonstrates the dramatic impact of the nanoscale morphology on the electrochemical performance of nanoporous materials and highlights the need for both shape and size control in dealloyed nanoporous metals.

  5. Nanoscale hotspots due to nonequilibrium thermal transport

    International Nuclear Information System (INIS)

    Sinha, Sanjiv; Goodson, Kenneth E.

    2004-01-01

    Recent experimental and modeling efforts have been directed towards the issue of temperature localization and hotspot formation in the vicinity of nanoscale heat generating devices. The nonequilibrium transport conditions which develop around these nanoscale devices results in elevated temperatures near the heat source which can not be predicted by continuum diffusion theory. Efforts to determine the severity of this temperature localization phenomena in silicon devices near and above room temperature are of technological importance to the development of microelectronics and other nanotechnologies. In this work, we have developed a new modeling tool in order to explore the magnitude of the additional thermal resistance which forms around nanoscale hotspots from temperatures of 100-1000K. The models are based on a two fluid approximation in which thermal energy is transferred between ''stationary'' optical phonons and fast propagating acoustic phonon modes. The results of the model have shown excellent agreement with experimental results of localized hotspots in silicon at lower temperatures. The model predicts that the effect of added thermal resistance due to the nonequilibrium phonon distribution is greatest at lower temperatures, but is maintained out to temperatures of 1000K. The resistance predicted by the numerical code can be easily integrated with continuum models in order to predict the temperature distribution around nanoscale heat sources with improved accuracy. Additional research efforts also focused on the measurements of the thermal resistance of silicon thin films at higher temperatures, with a focus on polycrystalline silicon. This work was intended to provide much needed experimental data on the thermal transport properties for micro and nanoscale devices built with this material. Initial experiments have shown that the exposure of polycrystalline silicon to high temperatures may induce recrystallization and radically increase the thermal

  6. Nanoscale thermal transport

    Science.gov (United States)

    Cahill, David G.; Ford, Wayne K.; Goodson, Kenneth E.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Merlin, Roberto; Phillpot, Simon R.

    2003-01-01

    Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid-solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The

  7. Morphology engineering of high performance binary oxide electrodes.

    Science.gov (United States)

    Chen, Kunfeng; Sun, Congting; Xue, Dongfeng

    2015-01-14

    Advances in materials have preceded almost every major technological leap since the beginning of civilization. On the nanoscale and microscale, mastery over the morphology, size, and structure of a material enables control of its properties and enhancement of its usefulness for a given application, such as energy storage. In this review paper, our aim is to present a review of morphology engineering of high performance oxide electrode materials for electrochemical energy storage. We begin with the chemical bonding theory of single crystal growth to direct the growth of morphology-controllable materials. We then focus on the growth of various morphologies of binary oxides and their electrochemical performances for lithium ion batteries and supercapacitors. The morphology-performance relationships are elaborated by selecting examples in which there is already reasonable understanding for this relationship. Based on these comprehensive analyses, we proposed colloidal supercapacitor systems beyond morphology control on the basis of system- and ion-level design. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

  8. Patterning high explosives at the nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Nafday, Omkar A.; Pitchimani, Rajasekar; Weeks, Brandon L. [Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409 (United States); Haaheim, Jason [NanoInk Inc., 8025 Lamon Ave., Skokie, IL 60077 (United States)

    2006-10-15

    For the first time, we have shown that spin coating and Dip pen nanolithography (DPN trademark) are simple methods of preparing energetic materials such as PETN and HMX on the nanoscale, requiring no heating of the energetic material. Nanoscale patterning has been demonstrated by the DPN method while continuous thin films were produced using the spin coating method. Results are presented for preparing continuous PETN thin films of nanometer thickness by the spin coating method and for controlling the architecture of arbitrary nanoscale patterns of PETN and HMX by the DPN method. These methods are simple for patterning energetic materials and can be extended beyond PETN and HMX, opening the door for fundamental studies at the nanoscale. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  9. Simulation of capillary bridges between nanoscale particles.

    Science.gov (United States)

    Dörmann, Michael; Schmid, Hans-Joachim

    2014-02-04

    Capillary forces are very important as they exceed in general other adhesion forces. But at the same time the exact calculation of these forces is very complex, so often assumptions and approximations are used. Previous research was done with regard to micrometer sized particles, but the behavior of nanoscale particles is different. Hence, the results for micrometer sized particles cannot be directly transferred when considering nanoscale particles. Therefore, a simulation method was developed to calculate numerically the shape of a rotationally symmetrical capillary bridge between two spherical particles or a particle and a plate. The capillary bridge in the gap between the particles is formed due to capillary condensation and is in thermodynamic equilibrium with the gas phase. Hence the Kelvin equation and the Young-Laplace equation can be used to calculate the profile of the capillary bridge, depending on the relative humidity of the surrounding air. The bridge profile consists of several elements that are determined consecutively and interpolated linearly. After the shape is determined, the volume and force, divided into capillary pressure force and surface tension force, can be calculated. The validation of this numerical model will be shown by comparison with several different analytical calculations for micrometer-sized particles. Furthermore, it is demonstrated that two often used approximations, (1) the toroidal approximation and (2) the use of an effective radius, cannot be used for nanoscale particles without remarkable mistake. It will be discussed how the capillary force and its components depend on different parameters, like particle size, relative humidity, contact angle, and distance, respectively. The rupture of a capillary bridge due to particle separation will also be presented.

  10. Nanoscale drug delivery for targeted chemotherapy.

    Science.gov (United States)

    Xin, Yong; Huang, Qian; Tang, Jian-Qin; Hou, Xiao-Yang; Zhang, Pei; Zhang, Long Zhen; Jiang, Guan

    2016-08-28

    Despite significant improvements in diagnostic methods and innovations in therapies for specific cancers, effective treatments for neoplastic diseases still represent major challenges. Nanotechnology as an emerging technology has been widely used in many fields and also provides a new opportunity for the targeted delivery of cancer drugs. Nanoscale delivery of chemotherapy drugs to the tumor site is highly desirable. Recent studies have shown that nanoscale drug delivery systems not only have the ability to destroy cancer cells but may also be carriers for chemotherapy drugs. Some studies have demonstrated that delivery of chemotherapy via nanoscale carriers has greater therapeutic benefit than either treatment modality alone. In this review, novel approaches to nanoscale delivery of chemotherapy are described and recent progress in this field is discussed. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH

    Science.gov (United States)

    This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nano...

  12. Identification of nanoscale ingredients in commercial food products and their induction of mitochondrially mediated cytotoxic effects on human mesenchymal stem cells.

    Science.gov (United States)

    Athinarayanan, Jegan; Alshatwi, Ali A; Periasamy, Vaiyapuri S; Al-Warthan, Abdulrahman A

    2015-02-01

    Titanium dioxide (E171) and silicon dioxide (E551) are common additives found in food products, personal-care products, and many other consumer products used in daily life. Recent studies have reported that these food additives (manufactured E171 and E551) contain nanosized particles of less than 100 nm. However, the particle size distribution and morphology of added TiO2 and SiO2 particles are not typically stated on the package label. Furthermore, there is an increasing debate regarding health and safety concerns related to the use of synthetic food additives containing nanosized ingredients in consumer products. In this study, we identified the size and morphology of TiO2 and SiO2 particles in commercially available food products by using transmission electron microscope (TEM). In addition, the in vitro toxicological effects of E171 and E551 on human mesenchymal stem cells (hMSCs), an adult stem cell-based model, were assessed using the MTT assay and a flow cytometry-based JC-1 assay. Our TEM results confirmed the presence of nanoscale ingredients in food products, and the in vitro toxicology results indicated that the nanoscale E171 and E551 ingredients induced dose-dependent cytotoxicity, changes in cellular morphology, and the loss of mitochondrial trans-membrane potential in hMSCs. These preliminary results clearly demonstrated that the nanoscale E171 and E551 particles had adverse effects on hMSCs by inducing oxidative stress-mediated cell death. Accordingly, further studies are needed to identify the specific pathway involved, with an emphasis on differential gene expression in hMSCs. © 2015 Institute of Food Technologists®

  13. Spintronics in nanoscale devices

    CERN Document Server

    Hedin, Eric R

    2013-01-01

    By exploiting the novel properties of quantum dots and nanoscale Aharonov-Bohm rings together with the electronic and magnetic properties of various semiconductor materials and graphene, researchers have conducted numerous theoretical and computational modeling studies and experimental tests that show promising behavior for spintronics applications. Spin polarization and spin-filtering capabilities and the ability to manipulate the electron spin state through external magnetic or electric fields have demonstrated the promise of workable nanoscale devices for computing and memory applications.

  14. Fractionation of Exosomes and DNA using Size-Based Separation at the Nanoscale

    Science.gov (United States)

    Wunsch, Benjamin; Smith, Joshua; Wang, Chao; Gifford, Stacey; Brink, Markus; Bruce, Robert; Solovitzky, Gustavo; Austin, Robert; Astier, Yann

    Exosomes, a key target of ``liquid biopsies'', are nano-vesicles found in nearly all biological fluids. Exosomes are secreted by eukaryotic and prokaryotic cells alike, and contain information about their originating cells, including surface proteins, cytoplasmic proteins, and nucleic acids. One challenge in studying exosome morphology is the difficulty of sorting exosomes by size and surface markers. Common separation techniques for exosomes include ultracentrifugation and ultrafiltration, for preparation of large volume samples, but these techniques often show contamination and significant heterogeneity between preparations. To date, deterministic lateral displacement (DLD) pillar arrays in silicon have proven an efficient technology to sort, separate, and enrich micron-scale particles including human parasites, eukaryotic cells, blood cells, and circulating tumor cells in blood; however, the DLD technology has never been translated to the true nanoscale, where it could function on bio-colloids such as exosomes. We have fabricated nanoscale DLD (nanoDLD) arrays capable of rapidly sorting colloids down to 20 nm in continuous flow, and demonstrated size sorting of individual exosome vesicles and dsDNA polymers, opening the potential for on-chip biomolecule separation and diagnosti

  15. Nanoscale phase change memory materials.

    Science.gov (United States)

    Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J

    2012-08-07

    Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.

  16. Tuning the Friction of Silicon Surfaces Using Nanopatterns at the Nanoscale

    Directory of Open Access Journals (Sweden)

    Jing Han

    2017-12-01

    Full Text Available Friction and wear become significant at small scale lengths, particularly in MEMS/NEMS. Nanopatterns are regarded as a potential approach to solve these problems. In this paper, we investigated the friction behavior of nanopatterned silicon surfaces with a periodical rectangular groove array in dry and wear-less single-asperity contact at the nanoscale using molecular dynamics simulations. The synchronous and periodic oscillations of the normal load and friction force with the sliding distance were determined at frequencies defined by the nanopattern period. The linear load dependence of the friction force is always observed for the nanopatterned surface and is independent of the nanopattern geometry. We show that the linear friction law is a formal Amontons’ friction law, while the significant linear dependence of the friction force-versus-real contact area and real contact area-versus-normal load captures the general features of the nanoscale friction for the nanopatterned surface. Interestingly, the nanopattern increases the friction force at the nanoscale, and the desired friction reduction is also observed. The enlargement and reduction of the friction critically depended on the nanopattern period rather than the area ratio. Our simulation results reveal that the nanopattern can modulate the friction behavior at the nanoscale from the friction signal to the friction law and to the value of the friction force. Thus, elaborate nanopatterning is an effective strategy for tuning the friction behavior at the nanoscale.

  17. Polaron Hopping in Nano-scale Poly(dA–Poly(dT DNA

    Directory of Open Access Journals (Sweden)

    Singh Mahi

    2010-01-01

    Full Text Available Abstract We investigate the current–voltage relationship and the temperature-dependent conductance of nano-scale samples of poly(dA–poly(dT DNA molecules. A polaron hopping model has been used to calculate the I–V characteristic of nano-scale samples of DNA. This model agrees with the data for current versus voltage at temperatures greater than 100 K. The quantities G 0 , i 0 , and T 1d are determined empirically, and the conductivity is estimated for samples of poly(dA–poly(dT.

  18. Nanoscale measurements of proton tracks using fluorescent nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sawakuchi, Gabriel O., E-mail: gsawakuchi@mdanderson.org; Sahoo, Narayan [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas 77030 (United States); Ferreira, Felisberto A. [Department of Nuclear Physics, University of Sao Paulo, SP 05508-090 (Brazil); McFadden, Conor H. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Hallacy, Timothy M. [Biophysics Program, Harvard University, Cambridge, Massachusetts 02138 (United States); Granville, Dal A. [Department of Medical Physics, The Ottawa Hospital Cancer Centre, Ottawa, Ontario K1H 8L6 (Canada); Akselrod, Mark S. [Crystal Growth Division, Landauer, Inc., Stillwater, Oklahoma 74074 (United States)

    2016-05-15

    Purpose: The authors describe a method in which fluorescence nuclear track detectors (FNTDs), novel track detectors with nanoscale spatial resolution, are used to determine the linear energy transfer (LET) of individual proton tracks from proton therapy beams by allowing visualization and 3D reconstruction of such tracks. Methods: FNTDs were exposed to proton therapy beams with nominal energies ranging from 100 to 250 MeV. Proton track images were then recorded by confocal microscopy of the FNTDs. Proton tracks in the FNTD images were fit by using a Gaussian function to extract fluorescence amplitudes. Histograms of fluorescence amplitudes were then compared with LET spectra. Results: The authors successfully used FNTDs to register individual proton tracks from high-energy proton therapy beams, allowing reconstruction of 3D images of proton tracks along with delta rays. The track amplitudes from FNTDs could be used to parameterize LET spectra, allowing the LET of individual proton tracks from therapeutic proton beams to be determined. Conclusions: FNTDs can be used to directly visualize proton tracks and their delta rays at the nanoscale level. Because the track intensities in the FNTDs correlate with LET, they could be used further to measure LET of individual proton tracks. This method may be useful for measuring nanoscale radiation quantities and for measuring the LET of individual proton tracks in radiation biology experiments.

  19. Exchange-coupled nanoscale SmCo/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dapeng; Poudyal, Narayan; Rong, Chuanbing; Zhang, Ying; Kramer, Matthew J.; Liu, J. Ping

    2012-05-11

    Nanoscalehybridmagnets containing SmCo5 and Nd2Fe14B hard magnetic phases have been produced via a novel “in-one-pot” processing route. The grain size of the processed bulk composite materials is controlled below 20 nm. The refinement of the nanoscale morphology leads to effective inter-phase exchange coupling that results in single-phase like magnetic properties. Energy product of 14 MGOe was obtained in the isotropic nanocomposite magnets at room temperature. At elevated temperatures, the hybridmagnets have greatly improved thermal stability compared to the Nd2Fe14B single-phase counterpart and have substantially increased magnetization and energy products compared to the single-phase SmCo5 counterpart.

  20. Self-assembly of nanoscale particles with biosurfactants and membrane scaffold proteins.

    Science.gov (United States)

    Faas, Ramona; Pohle, Annelie; Moß, Karin; Henkel, Marius; Hausmann, Rudolf

    2017-12-01

    Nanodiscs are membrane mimetics which may be used as tools for biochemical and biophysical studies of a variety of membrane proteins. These nanoscale structures are composed of a phospholipid bilayer held together by an amphipathic membrane scaffold protein (MSP). In the past, nanodiscs were successfully assembled with membrane scaffold protein 1D1 and 1,2-dipalmitoyl- sn -glycero-3-phosphorylcholine with a homogeneous diameter of ∼10 nm. In this study, the formation of nanoscale particles from MSP1D1 and rhamnolipid biosurfactants is investigated. Different protein to lipid ratios of 1:80, 1:90 and 1:100 were used for the assembly reaction, which were consecutively separated, purified and analyzed by size-exclusion chromatography (SEC) and dynamic light scattering (DLS). Size distributions were measured to determine homogeneity and confirm size dimensions. In this study, first evidence is presented on the formation of nanoscale particles with rhamnolipid biosurfactants and membrane scaffold proteins.

  1. ABC triblock copolymer vesicles with mesh-like morphology.

    Science.gov (United States)

    Zhao, Wei; Chen, Dian; Hu, Yunxia; Grason, Gregory M; Russell, Thomas P

    2011-01-25

    Polymer vesicles made from poly(isoprene-b-styrene-b-2-vinyl pyridine) (PI-b-PS-b-P2VP) triblock copolymer confined within the nanopores of an anodic aluminum oxide (AAO) membrane are studied. It was found that these vesicles have well-defined, nanoscopic size, and complex microphase-separated hydrophobic membranes, comprised of the PS and PI blocks, while the coronas are formed by the P2VP block. Vesicle formation was tracked using both transmission and scanning electron microscopy. A mesh-like morphology formed in the membrane at a well-defined composition of the three blocks that can be tuned by changing the copolymer composition. The nanoscale confinement, copolymer composition, and subtle molecular interactions contribute to the generation of these vesicles with such unusual morphologies.

  2. Enhanced nanoscale friction on fluorinated graphene.

    Science.gov (United States)

    Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

    2012-12-12

    Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene.

  3. Nanoscale Electrochemical Sensing and Processing in Microreactors

    NARCIS (Netherlands)

    Odijk, Mathieu; van den Berg, Albert

    2018-01-01

    In this review, we summarize recent advances in nanoscale electrochemistry, including the use of nanoparticles, carbon nanomaterials, and nanowires. Exciting developments are reported for nanoscale redox cycling devices, which can chemically amplify signal readout. We also discuss promising

  4. Morphology Analysis and Optimization: Crucial Factor Determining the Performance of Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Wenjin Zeng

    2017-03-01

    Full Text Available This review presents an overall discussion on the morphology analysis and optimization for perovskite (PVSK solar cells. Surface morphology and energy alignment have been proven to play a dominant role in determining the device performance. The effect of the key parameters such as solution condition and preparation atmosphere on the crystallization of PVSK, the characterization of surface morphology and interface distribution in the perovskite layer is discussed in detail. Furthermore, the analysis of interface energy level alignment by using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy is presented to reveals the correlation between morphology and charge generation and collection within the perovskite layer, and its influence on the device performance. The techniques including architecture modification, solvent annealing, etc. were reviewed as an efficient approach to improve the morphology of PVSK. It is expected that further progress will be achieved with more efforts devoted to the insight of the mechanism of surface engineering in the field of PVSK solar cells.

  5. Nanoscale size effects on the mechanical properties of platinum thin films and cross-sectional grain morphology

    KAUST Repository

    Abbas, K

    2015-12-10

    © 2016 IOP Publishing Ltd. The mechanical behavior of polycrystalline Pt thin films is reported for thicknesses of 75 nm, 100 nm, 250 nm, and 400 nm. These thicknesses correspond to transitions between nanocrystalline grain morphology types as found in TEM studies. Thinner samples display a brittle behavior, but as thickness increases the grain morphology evolves, leading to a ductile behavior. During evolution of the morphology, dramatic differences in elastic moduli (105-160 GPa) and strengths (560-1700 MPa) are recorded and explained by the variable morphology. This work suggests that in addition to the in-plane grain size of thin films, the transitions in cross-sectional morphologies of the Pt films significantly affect their mechanical behavior.

  6. Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

    Energy Technology Data Exchange (ETDEWEB)

    Wang Mu [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Ruan Yuxia [Department of Ophthalmology, The First Affiliated Hospital, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Xing Xiaobo; Chen Qian; Peng, Yuan [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China); Cai Jiye, E-mail: tjycai@jnu.edu.cn [Department of Chemistry, Jinan University, 601 Huangpu Road West, Tianhe District, Guangzhou 510632 (China)

    2011-07-04

    Graphical abstract: Highlights: > In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. > We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. > Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. > The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 {+-} 4.62 nm to 129.70 {+-} 43.72 nm) and the expression of CD44 decreased (99.79 {+-} 0.16% to 75.14 {+-} 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 {mu}M curcumin-treated) and 50-120 pN (20 {mu}M curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

  7. Curcumin induced nanoscale CD44 molecular redistribution and antigen-antibody interaction on HepG2 cell surface

    International Nuclear Information System (INIS)

    Wang Mu; Ruan Yuxia; Xing Xiaobo; Chen Qian; Peng, Yuan; Cai Jiye

    2011-01-01

    Graphical abstract: Highlights: → In this study, we investigate the changes of CD44 expression and distribution on HepG2 cells after curcumin treatment. → We find curcumin is able to change the morphology and ultrastructure of HepG2 cells. → Curcumin can reduce the expression of CD44 molecules and induce the nanoscale molecular redistribution on cell surface. → The binding force between CD44-modified AFM tip and the HepG2 cell surface decreases after curcumin-treatment. - Abstract: The cell surface glycoprotein CD44 was implicated in the progression, metastasis and apoptosis of certain human tumors. In this study, we used atomic force microscope (AFM) to monitor the effect of curcumin on human hepatocellular carcinoma (HepG2) cell surface nanoscale structure. High-resolution imaging revealed that cell morphology and ultrastructure changed a lot after being treated with curcumin. The membrane average roughness increased (10.88 ± 4.62 nm to 129.70 ± 43.72 nm) and the expression of CD44 decreased (99.79 ± 0.16% to 75.14 ± 8.37%). Laser scanning confocal microscope (LSCM) imaging showed that CD44 molecules were located on the cell membrane. The florescence intensity in control group was weaker than that in curcumin treated cells. Most of the binding forces between CD44 antibodies and untreated HepG2 cell membrane were around 120-220 pN. After being incubated with curcumin, the major forces focused on 70-150 pN (10 μM curcumin-treated) and 50-120 pN (20 μM curcumin-treated). These results suggested that, as result of nanoscale molecular redistribution, changes of the cell surface were in response to external treatment of curcumin. The combination of AFM and LSCM could be a powerful method to detect the distribution of cell surface molecules and interactions between molecules and their ligands.

  8. Morphological Diversity and the Roles of Contingency, Chance and Determinism in African Cichlid Radiations

    Science.gov (United States)

    Young, Kyle A.; Snoeks, Jos; Seehausen, Ole

    2009-01-01

    Background Deterministic evolution, phylogenetic contingency and evolutionary chance each can influence patterns of morphological diversification during adaptive radiation. In comparative studies of replicate radiations, convergence in a common morphospace implicates determinism, whereas non-convergence suggests the importance of contingency or chance. Methodology/Principal Findings The endemic cichlid fish assemblages of the three African great lakes have evolved similar sets of ecomorphs but show evidence of non-convergence when compared in a common morphospace, suggesting the importance of contingency and/or chance. We then analyzed the morphological diversity of each assemblage independently and compared their axes of diversification in the unconstrained global morphospace. We find that despite differences in phylogenetic composition, invasion history, and ecological setting, the three assemblages are diversifying along parallel axes through morphospace and have nearly identical variance-covariance structures among morphological elements. Conclusions/Significance By demonstrating that replicate adaptive radiations are diverging along parallel axes, we have shown that non-convergence in the common morphospace is associated with convergence in the global morphospace. Applying these complimentary analyses to future comparative studies will improve our understanding of the relationship between morphological convergence and non-convergence, and the roles of contingency, chance and determinism in driving morphological diversification. PMID:19270732

  9. EXAFS and XANES analysis of oxides at the nanoscale

    Directory of Open Access Journals (Sweden)

    Alexei Kuzmin

    2014-11-01

    Full Text Available Worldwide research activity at the nanoscale is triggering the appearance of new, and frequently surprising, materials properties in which the increasing importance of surface and interface effects plays a fundamental role. This opens further possibilities in the development of new multifunctional materials with tuned physical properties that do not arise together at the bulk scale. Unfortunately, the standard methods currently available for solving the atomic structure of bulk crystals fail for nanomaterials due to nanoscale effects (very small crystallite sizes, large surface-to-volume ratio, near-surface relaxation, local lattice distortions etc.. As a consequence, a critical reexamination of the available local-structure characterization methods is needed. This work discusses the real possibilities and limits of X-ray absorption spectroscopy (XAS analysis at the nanoscale. To this end, the present state of the art for the interpretation of extended X-ray absorption fine structure (EXAFS is described, including an advanced approach based on the use of classical molecular dynamics and its application to nickel oxide nanoparticles. The limits and possibilities of X-ray absorption near-edge spectroscopy (XANES to determine several effects associated with the nanocrystalline nature of materials are discussed in connection with the development of ZnO-based dilute magnetic semiconductors (DMSs and iron oxide nanoparticles.

  10. From nano to micro: topographical scale and its impact on cell adhesion, morphology and contact guidance

    International Nuclear Information System (INIS)

    Nguyen, Anh Tuan; Sathe, Sharvari R; Yim, Evelyn K F

    2016-01-01

    Topography, among other physical factors such as substrate stiffness and extracellular forces, is known to have a great influence on cell behaviours. Optimization of topographical features, in particular topographical dimensions ranging from nanoscale to microscale, is the key strategy to obtain the best cellular performance for various applications in tissue engineering and regenerative medicine. In this review, we provide a comprehensive survey on the significance of sizes of topography and their impacts on cell adhesion, morphology and alignment, and neurite guidance. Also recent works mimicking the hierarchical structure of natural extracellular matrix by combining both nanoscale and microscale topographies are highlighted. (topical review)

  11. Theory and simulation studies of effective interactions, phase behavior and morphology in polymer nanocomposites.

    Science.gov (United States)

    Ganesan, Venkat; Jayaraman, Arthi

    2014-01-07

    Polymer nanocomposites are a class of materials that consist of a polymer matrix filled with inorganic/organic nanoscale additives that enhance the inherent macroscopic (mechanical, optical and electronic) properties of the polymer matrix. Over the past few decades such materials have received tremendous attention from experimentalists, theoreticians, and computational scientists. These studies have revealed that the macroscopic properties of polymer nanocomposites depend strongly on the (microscopic) morphology of the constituent nanoscale additives in the polymer matrix. As a consequence, intense research efforts have been directed to understand the relationships between interactions, morphology, and the phase behavior of polymer nanocomposites. Theory and simulations have proven to be useful tools in this regard due to their ability to link molecular level features of the polymer and nanoparticle additives to the resulting morphology within the composite. In this article we review recent theory and simulation studies, presenting briefly the methodological developments underlying PRISM theories, density functional theory, self-consistent field theory approaches, and atomistic and coarse-grained molecular simulations. We first discuss the studies on polymer nanocomposites with bare or un-functionalized nanoparticles as additives, followed by a review of recent work on composites containing polymer grafted or functionalized nanoparticles as additives. We conclude each section with a brief outlook on some potential future directions.

  12. DNA-based construction at the nanoscale: emerging trends and applications

    Science.gov (United States)

    Lourdu Xavier, P.; Chandrasekaran, Arun Richard

    2018-02-01

    The field of structural DNA nanotechnology has evolved remarkably—from the creation of artificial immobile junctions to the recent DNA-protein hybrid nanoscale shapes—in a span of about 35 years. It is now possible to create complex DNA-based nanoscale shapes and large hierarchical assemblies with greater stability and predictability, thanks to the development of computational tools and advances in experimental techniques. Although it started with the original goal of DNA-assisted structure determination of difficult-to-crystallize molecules, DNA nanotechnology has found its applications in a myriad of fields. In this review, we cover some of the basic and emerging assembly principles: hybridization, base stacking/shape complementarity, and protein-mediated formation of nanoscale structures. We also review various applications of DNA nanostructures, with special emphasis on some of the biophysical applications that have been reported in recent years. In the outlook, we discuss further improvements in the assembly of such structures, and explore possible future applications involving super-resolved fluorescence, single-particle cryo-electron (cryo-EM) and x-ray free electron laser (XFEL) nanoscopic imaging techniques, and in creating new synergistic designer materials.

  13. Nanoscale technology in biological systems

    CERN Document Server

    Greco, Ralph S; Smith, R Lane

    2004-01-01

    Reviewing recent accomplishments in the field of nanobiology Nanoscale Technology in Biological Systems introduces the application of nanoscale matrices to human biology. It focuses on the applications of nanotechnology fabrication to biomedical devices and discusses new physical methods for cell isolation and manipulation and intracellular communication at the molecular level. It also explores the application of nanobiology to cardiovascular diseases, oncology, transplantation, and a range of related disciplines. This book build a strong background in nanotechnology and nanobiology ideal for

  14. An Indentation Technique for Nanoscale Dynamic Viscoelastic Measurements at Elevated Temperature

    Science.gov (United States)

    Ye, Jiping

    2012-08-01

    Determination of nano/micro-scale viscoelasticity is very important to understand the local rheological behavior and degradation phenomena of multifunctional polymer blend materials. This article reviews research results concerning the development of indentation techniques for making nanoscale dynamic viscoelastic measurements at elevated temperature. In the last decade, we have achieved breakthroughs in noise floor reduction in air and thermal load drift/noise reduction at high temperature before taking on the challenge of nanoscale viscoelastic measurements. A high-temperature indentation technique has been developed that facilitates viscoelastic measurements up to 200 °C in air and 500 °C in a vacuum. During the last year, two viscoelastic measurement methods have been developed by making a breakthrough in suppressing the contact area change at high temperature. One is a sharp-pointed time-dependent nanoindentation technique for microscale application and the other is a spherical time-dependent nanoindentation technique for nanoscale application. In the near future, we expect to lower the thermal load drift and load noise floor even more substantially.

  15. Creating nanoscale emulsions using condensation.

    Science.gov (United States)

    Guha, Ingrid F; Anand, Sushant; Varanasi, Kripa K

    2017-11-08

    Nanoscale emulsions are essential components in numerous products, ranging from processed foods to novel drug delivery systems. Existing emulsification methods rely either on the breakup of larger droplets or solvent exchange/inversion. Here we report a simple, scalable method of creating nanoscale water-in-oil emulsions by condensing water vapor onto a subcooled oil-surfactant solution. Our technique enables a bottom-up approach to forming small-scale emulsions. Nanoscale water droplets nucleate at the oil/air interface and spontaneously disperse within the oil, due to the spreading dynamics of oil on water. Oil-soluble surfactants stabilize the resulting emulsions. We find that the oil-surfactant concentration controls the spreading behavior of oil on water, as well as the peak size, polydispersity, and stability of the resulting emulsions. Using condensation, we form emulsions with peak radii around 100 nm and polydispersities around 10%. This emulsion formation technique may open different routes to creating emulsions, colloidal systems, and emulsion-based materials.

  16. Nanoscale thermal transport: Theoretical method and application

    Science.gov (United States)

    Zeng, Yu-Jia; Liu, Yue-Yang; Zhou, Wu-Xing; Chen, Ke-Qiu

    2018-03-01

    With the size reduction of nanoscale electronic devices, the heat generated by the unit area in integrated circuits will be increasing exponentially, and consequently the thermal management in these devices is a very important issue. In addition, the heat generated by the electronic devices mostly diffuses to the air in the form of waste heat, which makes the thermoelectric energy conversion also an important issue for nowadays. In recent years, the thermal transport properties in nanoscale systems have attracted increasing attention in both experiments and theoretical calculations. In this review, we will discuss various theoretical simulation methods for investigating thermal transport properties and take a glance at several interesting thermal transport phenomena in nanoscale systems. Our emphasizes will lie on the advantage and limitation of calculational method, and the application of nanoscale thermal transport and thermoelectric property. Project supported by the Nation Key Research and Development Program of China (Grant No. 2017YFB0701602) and the National Natural Science Foundation of China (Grant No. 11674092).

  17. 3D-morphology reconstruction of nanoscale phase-separation in polymer memory blends

    NARCIS (Netherlands)

    Khikhlovskyi, S.; Breemen, van A.J.J.M.; Michels, J.J.; Janssen, R.A.J.; Gelinck, G.; Kemerink, M.

    2015-01-01

    In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple

  18. Flexible nanoscale high-performance FinFETs

    KAUST Repository

    Sevilla, Galo T.

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics.

  19. Negative pressure characteristics of an evaporating meniscus at nanoscale

    Directory of Open Access Journals (Sweden)

    Maroo Shalabh

    2011-01-01

    Full Text Available Abstract This study aims at understanding the characteristics of negative liquid pressures at the nanoscale using molecular dynamics simulation. A nano-meniscus is formed by placing liquid argon on a platinum wall between two nano-channels filled with the same liquid. Evaporation is simulated in the meniscus by increasing the temperature of the platinum wall for two different cases. Non-evaporating films are obtained at the center of the meniscus. The liquid film in the non-evaporating and adjacent regions is found to be under high absolute negative pressures. Cavitation cannot occur in these regions as the capillary height is smaller than the critical cavitation radius. Factors which determine the critical film thickness for rupture are discussed. Thus, high negative liquid pressures can be stable at the nanoscale, and utilized to create passive pumping devices as well as significantly enhance heat transfer rates.

  20. Nanoscale tissue engineering: spatial control over cell-materials interactions

    Science.gov (United States)

    Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G.; Jabbari, Esmaiel; Khademhosseini, Ali

    2011-01-01

    Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness the interactions through nanoscale biomaterials engineering in order to study and direct cellular behaviors. Here, we review the nanoscale tissue engineering technologies for both two- and three-dimensional studies (2- and 3D), and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffolds technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D, however, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and the temporal changes in cellular microenvironment. PMID:21451238

  1. Nanoscale tissue engineering: spatial control over cell-materials interactions

    International Nuclear Information System (INIS)

    Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G; Khademhosseini, Ali; Jabbari, Esmaiel

    2011-01-01

    Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness these interactions through nanoscale biomaterials engineering in order to study and direct cellular behavior. Here, we review two- and three-dimensional (2- and 3D) nanoscale tissue engineering technologies, and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffold technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D. However, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and that can control the temporal changes in the cellular microenvironment. (topical review)

  2. Genetic Determinism vs. Phenotypic Plasticity in Protist Morphology.

    Science.gov (United States)

    Mulot, Matthieu; Marcisz, Katarzyna; Grandgirard, Lara; Lara, Enrique; Kosakyan, Anush; Robroek, Bjorn J M; Lamentowicz, Mariusz; Payne, Richard J; Mitchell, Edward A D

    2017-11-01

    Untangling the relationships between morphology and phylogeny is key to building a reliable taxonomy, but is especially challenging for protists, where the existence of cryptic or pseudocryptic species makes finding relevant discriminant traits difficult. Here we use Hyalosphenia papilio (a testate amoeba) as a model species to investigate the contribution of phylogeny and phenotypic plasticity in its morphology. We study the response of H. papilio morphology (shape and pores number) to environmental variables in (i) a manipulative experiment with controlled conditions (water level), (ii) an observational study of a within-site natural ecological gradient (water level), and (iii) an observational study across 37 European peatlands (climate). We showed that H. papilio morphology is correlated to environmental conditions (climate and water depth) as well as geography, while no relationship between morphology and phylogeny was brought to light. The relative contribution of genetic inheritance and phenotypic plasticity in shaping morphology varies depending on the taxonomic group and the trait under consideration. Thus, our data call for a reassessment of taxonomy based on morphology alone. This clearly calls for a substantial increase in taxonomic research on these globally still under-studied organisms leading to a reassessment of estimates of global microbial eukaryotic diversity. © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.

  3. Traceable nanoscale measurement at NML-SIRIM

    International Nuclear Information System (INIS)

    Dahlan, Ahmad M.; Abdul Hapip, A. I.

    2012-01-01

    The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

  4. Traceable nanoscale measurement at NML-SIRIM

    Science.gov (United States)

    Dahlan, Ahmad M.; Abdul Hapip, A. I.

    2012-06-01

    The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

  5. Traceable nanoscale measurement at NML-SIRIM

    Energy Technology Data Exchange (ETDEWEB)

    Dahlan, Ahmad M.; Abdul Hapip, A. I. [National Metrology Laboratory SIRIM Berhad (NML-SIRIM), Lot PT 4803, Bandar Baru Salak Tinggi, 43900 Sepang (Malaysia)

    2012-06-29

    The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

  6. Nanoscale Analysis of a Hierarchical Hybrid Solar Cell in 3D.

    Science.gov (United States)

    Divitini, Giorgio; Stenzel, Ole; Ghadirzadeh, Ali; Guarnera, Simone; Russo, Valeria; Casari, Carlo S; Bassi, Andrea Li; Petrozza, Annamaria; Di Fonzo, Fabio; Schmidt, Volker; Ducati, Caterina

    2014-05-01

    A quantitative method for the characterization of nanoscale 3D morphology is applied to the investigation of a hybrid solar cell based on a novel hierarchical nanostructured photoanode. A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography. It is found that the hierarchical titania nanostructure facilitates polymer infiltration, thus favoring intermixing of the two semiconducting phases, essential for charge separation. The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell. In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent.

  7. The Architectural Designs of a Nanoscale Computing Model

    Directory of Open Access Journals (Sweden)

    Mary M. Eshaghian-Wilner

    2004-08-01

    Full Text Available A generic nanoscale computing model is presented in this paper. The model consists of a collection of fully interconnected nanoscale computing modules, where each module is a cube of cells made out of quantum dots, spins, or molecules. The cells dynamically switch between two states by quantum interactions among their neighbors in all three dimensions. This paper includes a brief introduction to the field of nanotechnology from a computing point of view and presents a set of preliminary architectural designs for fabricating the nanoscale model studied.

  8. Passive film growth on carbon steel and its nanoscale features at various passivating potentials

    International Nuclear Information System (INIS)

    Li, Yuan; Cheng, Y. Frank

    2017-01-01

    Highlights: • Imaged the topography of passivated steel at various film-forming potentials. • Characterized the nanoscale features of passive films. • Determined the composition of passive films formed at various potentials. - Abstract: In this work, the passivation and topographic sub-structure of passive films on a carbon steel in a carbonate/bicarbonate solution was characterized by electrochemical measurements, atomic force microscopy and X-ray photoelectron spectroscopy. When passivating at a potential near the active-passive transition, the film contains the mixture of Fe_3O_4, Fe_2O_3 and FeOOH, with numerous nanoscale features. As the film-forming potential shifts positively, the passive film becomes more compact and the nanoscale features disappear. When the film is formed at a passive potential where the oxygen evolution is enabled, the content of FeOOH in the film increases, resulting in an amorphous topography and reduced corrosion resistance.

  9. Nanoscale Structure of Type I Collagen Fibrils: Quantitative Measurement of D-spacing

    Science.gov (United States)

    Erickson, Blake; Fang, Ming; Wallace, Joseph M.; Orr, Bradford G.; Les, Clifford M.; Holl, Mark M. Banaszak

    2012-01-01

    This paper details a quantitative method to measure the D-periodic spacing of Type I collagen fibrils using Atomic Force Microscopy coupled with analysis using a 2D Fast Fourier Transform approach. Instrument calibration, data sampling and data analysis are all discussed and comparisons of the data to the complementary methods of electron microscopy and X-ray scattering are made. Examples of the application of this new approach to the analysis of Type I collagen morphology in disease models of estrogen depletion and Osteogenesis Imperfecta are provided. We demonstrate that it is the D-spacing distribution, not the D-spacing mean, that showed statistically significant differences in estrogen depletion associated with early stage Osteoporosis and Osteogenesis Imperfecta. The ability to quantitatively characterize nanoscale morphological features of Type I collagen fibrils will provide important structural information regarding Type I collagen in many research areas, including tissue aging and disease, tissue engineering, and gene knock out studies. Furthermore, we also envision potential clinical applications including evaluation of tissue collagen integrity under the impact of diseases or drug treatments. PMID:23027700

  10. Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

    Science.gov (United States)

    Cathcart, Nicole; Kitaev, Vladimir

    2016-09-01

    A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

  11. Nanoscale hydroxyapatite particles for bone tissue engineering.

    Science.gov (United States)

    Zhou, Hongjian; Lee, Jaebeom

    2011-07-01

    Hydroxyapatite (HAp) exhibits excellent biocompatibility with soft tissues such as skin, muscle and gums, making it an ideal candidate for orthopedic and dental implants or components of implants. Synthetic HAp has been widely used in repair of hard tissues, and common uses include bone repair, bone augmentation, as well as coating of implants or acting as fillers in bone or teeth. However, the low mechanical strength of normal HAp ceramics generally restricts its use to low load-bearing applications. Recent advancements in nanoscience and nanotechnology have reignited investigation of nanoscale HAp formation in order to clearly define the small-scale properties of HAp. It has been suggested that nano-HAp may be an ideal biomaterial due to its good biocompatibility and bone integration ability. HAp biomedical material development has benefited significantly from advancements in nanotechnology. This feature article looks afresh at nano-HAp particles, highlighting the importance of size, crystal morphology control, and composites with other inorganic particles for biomedical material development. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Nanoscale size effects on the mechanical properties of platinum thin films and cross-sectional grain morphology

    KAUST Repository

    Abbas, K; Alaie, S; Ghasemi Baboly, M; Elahi, M M M; Anjum, Dalaver H.; Chaieb, Saharoui; Leseman, Z C

    2015-01-01

    -1700 MPa) are recorded and explained by the variable morphology. This work suggests that in addition to the in-plane grain size of thin films, the transitions in cross-sectional morphologies of the Pt films significantly affect their mechanical behavior.

  13. Structural Modification and Self-Assembly of Nanoscale Magnetite Synthesised in the Presence of an Anionic Surfactant

    Directory of Open Access Journals (Sweden)

    Malik S.

    2014-07-01

    Full Text Available The earliest reported medical use of magnetite powder for internal applications was in the 10th century A.D. by the Persian physician and philosopher Avicenna of Bokhara [1,2]. Today magnetic nanoparticles are used for magnetic resonance imaging (MRI and are potential colloidal mediators for cancer magnetic hyperthermia [3]. Twenty years ago magnetite (Fe3O4 was found to be present in the human brain [4] and more recently it has been reported that nanoscale biogenic magnetite (origin and formation uncertain is associated with neurodegenerative diseases such as Parkinson’s, Huntington’s and Alzheimer’s [5]. Here we show that the synthesis of magnetite in the presence of the surfactant sodium dodecyl sulphate (SDS gives rise to a variety of nanoscale morphologies, some of which look remarkably similar to magnetite found in organisms, suggesting that similar processes may be involved. Furthermore, these 1D materials with diameters of quantum confined size are of interest in the areas of biosensors [6] and biomedical imaging [7].

  14. In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de; Madsen, Morten; Kjelstrup-Hansen, Jakob

    2010-01-01

    Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P) could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electri......Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P) could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes...... patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens...... the possibility for large-scale optoelectronic device fabrication....

  15. Nanoscale structure, dynamics and power conversion efficiency correlations in small molecule and oligomer-based photovoltaic devices

    Science.gov (United States)

    Szarko, Jodi M.; Guo, Jianchang; Rolczynski, Brian S.; Chen, Lin X.

    2011-01-01

    Photovoltaic functions in organic materials are intimately connected to interfacial morphologies of molecular packing in films on the nanometer scale and molecular levels. This review will focus on current studies on correlations of nanoscale morphologies in organic photovoltaic (OPV) materials with fundamental processes relevant to photovoltaic functions, such as light harvesting, exciton splitting, exciton diffusion, and charge separation (CS) and diffusion. Small molecule photovoltaic materials will be discussed here. The donor and acceptor materials in small molecule OPV devices can be fabricated in vacuum-deposited, multilayer, crystalline thin films, or spin-coated together to form blended bulk heterojunction (BHJ) films. These two methods result in very different morphologies of the solar cell active layers. There is still a formidable debate regarding which morphology is favored for OPV optimization. The morphology of the conducting films has been systematically altered; using variations of the techniques above, the whole spectrum of film qualities can be fabricated. It is possible to form a highly crystalline material, one which is completely amorphous, or an intermediate morphology. In this review, we will summarize the past key findings that have driven organic solar cell research and the current state-of-the-art of small molecule and conducting oligomer materials. We will also discuss the merits and drawbacks of these devices. Finally, we will highlight some works that directly compare the spectra and morphology of systematically elongated oligothiophene derivatives and compare these oligomers to their polymer counterparts. We hope this review will shed some new light on the morphology differences of these two systems. PMID:22110870

  16. Nanoscale heterostructures with molecular-scale single-crystal metal wires.

    Science.gov (United States)

    Kundu, Paromita; Halder, Aditi; Viswanath, B; Kundu, Dipan; Ramanath, Ganpati; Ravishankar, N

    2010-01-13

    Creating nanoscale heterostructures with molecular-scale (synthesis of nanoscale heterostructures with single-crystal molecular-scale Au nanowires attached to different nanostructure substrates. Our method involves the formation of Au nanoparticle seeds by the reduction of rocksalt AuCl nanocubes heterogeneously nucleated on the substrates and subsequent nanowire growth by oriented attachment of Au nanoparticles from the solution phase. Nanoscale heterostructures fabricated by such site-specific nucleation and growth are attractive for many applications including nanoelectronic device wiring, catalysis, and sensing.

  17. Passive film growth on carbon steel and its nanoscale features at various passivating potentials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuan; Cheng, Y. Frank, E-mail: fcheng@ucalgary.ca

    2017-02-28

    Highlights: • Imaged the topography of passivated steel at various film-forming potentials. • Characterized the nanoscale features of passive films. • Determined the composition of passive films formed at various potentials. - Abstract: In this work, the passivation and topographic sub-structure of passive films on a carbon steel in a carbonate/bicarbonate solution was characterized by electrochemical measurements, atomic force microscopy and X-ray photoelectron spectroscopy. When passivating at a potential near the active-passive transition, the film contains the mixture of Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3} and FeOOH, with numerous nanoscale features. As the film-forming potential shifts positively, the passive film becomes more compact and the nanoscale features disappear. When the film is formed at a passive potential where the oxygen evolution is enabled, the content of FeOOH in the film increases, resulting in an amorphous topography and reduced corrosion resistance.

  18. Adhesion Dynamics in Probing Micro- and Nanoscale Thin Solid Films

    Directory of Open Access Journals (Sweden)

    Xiaoling He

    2008-01-01

    Full Text Available This study focuses on modeling the probe dynamics in scratching and indenting thin solid films at micro- and nanoscales. The model identifies bifurcation conditions that define the stick-slip oscillation patterns of the tip. It is found that the local energy fluctuations as a function of the inelastic deformation, defect formation, material properties, and contact parameters determine the oscillation behavior. The transient variation of the localized function makes the response nonlinear at the adhesion junction. By quantifying the relation between the bifurcation parameters and the oscillation behavior, this model gives a realistic representation of the complex adhesion dynamics. Specifically, the model establishes the link between the stick-slip behavior and the inelastic deformation and the local potentials. This model justifies the experimental observations and the molecular dynamics simulation of the adhesion and friction dynamics in both the micro- and nanoscale contact.

  19. Nanoscale mapping and organization analysis of target proteins on cancer cells from B-cell lymphoma patients

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mi [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xiao, Xiubin [Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing 100071 (China); Liu, Lianqing, E-mail: lqliu@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Xi, Ning, E-mail: xin@egr.msu.edu [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Wang, Yuechao; Dong, Zaili [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, Weijing, E-mail: zhangwj3072@163.com [Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing 100071 (China)

    2013-11-01

    CD20, a membrane protein highly expressed on most B-cell lymphomas, is an effective target demonstrated in clinical practice for treating B-cell non-Hodgkin's lymphoma (NHL). Rituximab is a monoclonal antibody against CD20. In this work, we applied atomic force microscopy (AFM) to map the nanoscale distribution of CD20 molecules on the surface of cancer cells from clinical B-cell NHL patients under the assistance of ROR1 fluorescence recognition (ROR1 is a specific cell surface marker exclusively expressed on cancer cells). First, the ROR1 fluorescence labeling experiments showed that ROR1 was expressed on cancer cells from B-cell lymphoma patients, but not on normal cells from healthy volunteers. Next, under the guidance of ROR1 fluorescence, the rituximab-conjugated AFM tips were moved to cancer cells to image the cellular morphologies and detect the CD20-rituximab interactions on the cell surfaces. The distribution maps of CD20 on cancer cells were constructed by obtaining arrays of (16×16) force curves in local areas (500×500 nm{sup 2}) on the cell surfaces. The experimental results provide a new approach to directly investigate the nanoscale distribution of target protein on single clinical cancer cells. - Highlights: • Cancer cells were recognized from healthy cells by ROR1 fluorescence labeling. • The nanoscale distribution of CD20 on cancer cells was characterized. • The distribution of CD20 was non-uniform on the surface of cancer cells.

  20. Electron confinement in thin metal films. Structure, morphology and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dil, J.H.

    2006-05-15

    This thesis investigates the interplay between reduced dimensionality, electronic structure, and interface effects in ultrathin metal layers (Pb, In, Al) on a variety of substrates (Si, Cu, graphite). These layers can be grown with such a perfection that electron confinement in the direction normal to the film leads to the occurrence of quantum well states in their valence bands. These quantum well states are studied in detail, and their behaviour with film thickness, on different substrates, and other parameters of growth are used here to characterise a variety of physical properties of such nanoscale systems. The sections of the thesis deal with a determination of quantum well state energies for a large data set on different systems, the interplay between film morphology and electronic structure, and the influence of substrate electronic structure on their band shape; finally, new ground is broken by demonstrating electron localization and correlation effects, and the possibility to measure the influence of electron-phonon coupling in bulk bands. (orig.)

  1. A surface evolution scheme to identify nanoscale intrinsic geometry from AFM experimental data

    International Nuclear Information System (INIS)

    Jang, Hong-Lae; Kim, Hyun-Seok; Park, Youmie; Cho, Seonho

    2013-01-01

    The geometrical properties of metallic nanoparticles such as the size and morphology have significant impacts on the structure and stability of the adsorbed biological entities as well as the nanoscale structural performances. To identify the nanoscale intrinsic geometry from the height images by atomic force microscopy (AFM), we developed a curvature-dependent evolution scheme that can eliminate the noise and smoothen the surfaces. The principal curvatures are computed directly from the first and second derivatives of the discrete AFM height data. The principal curvatures and directions correspond to the eigenvalues and eigenvectors of shape operator matrix, respectively. The evolution equation using the principal curvature flows smoothens the images in the corresponding principal directions. For an idealized model, κ 2 flow successfully identifies the major valley lines to represent the boundary of nanoparticles without referring to the phase information, whereas the mean curvature flow eliminates all the minor ones leaving only the major feature of the boundary. To demonstrate the capability of noise removal, smoothing surfaces, the identification of ridge and valley lines, and the extraction of intrinsic geometry, the developed numerical scheme is applied to real AFM data that include the silver nanoparticles of 24 nm diameter and the gold nanoparticles of 33–56 nm diameters

  2. Nanoscale thermal transport. II. 2003–2012

    OpenAIRE

    Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

    2013-01-01

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of th...

  3. Soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB ferromagnetic materials and their characterization

    Science.gov (United States)

    Rao, G. V. S. Jayapala; Prasad, T. N. V. K. V.; Shameer, Syed; Rao, M. Purnachandra

    2018-04-01

    Neodymium iron boron (NdFeB) permanent magnets have high energy product with suitable magnetic and physical properties for an array of applications including power generation and motors. However, synthetic routes of NdFeB permanent magnets involve critical procedures with high energy and needs scientific skills. Herein, we report on soapnut extract mediated synthesis of nanoscale cobalt substituted NdFeB (Co-NdFeB) permanent magnetic powders (Nd: 15%, Fe: 77.5%, B: 7.5% and Co with molar ratios: 0.5, 1, 1.5 and 2). A 10 ml of 10% soapnut extract was added to 90 ml of respective chemical composition and heated to 60 °C for 30 min and aged for 24 h. The dried powder was sintered at 500 °C for 1 h. The characterization of the prepared nanoscale Co-NdFeB magnetic powders was done using the techniques such as Dynamic Light Scattering (DLS for size and zeta potential measurements), X-ray diffraction (XRD) for structural determination, Scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS) for surface morphological and elemental analysis, Fourier transform infrared spectroscopy (FT-IR) for the identification of functional groups associated and hysteresis loop studies to quantify the magnetization. The results revealed that particles were in irregular and tubular shaped and highly stable (Zeta potential: -44.4 mV) with measured size <100 nm. XRD micrographs revealed a tetragonal crystal structure and FTIR showed predominant N-H and O-H stretching indicates the involvement of these functional groups in the reduction and stabilization process of Co-NdFeB magnetic powders. Hysteresis studies signify the effect of an increase in Co concentration.

  4. Determination of morphological and cytological differences between diploid and tetraploid watermelon plants

    Directory of Open Access Journals (Sweden)

    İsmail ŞİMŞEK

    2013-06-01

    Full Text Available In the seedless watermelon breeding programme, firstly, tetraploid parents must be developed by the breeders. When diploid watermelon lines treated with colchicine and oryzaline in vivo and vitro conditions, tetraploid plants could be obtained. The diploid and tetraploid watermelon plants should be selected within the population. For this reason, some markers (morphological, isozyme, cytological and molecular techniques are needed to separate from diploid and tetraploid plants. Chromosome counts and DNA content of diploid and tetraploid plants as a result of measurement of flow cytometry distinction can be made definitively. However, the laboratory infrastructure required to implement each method, is not economical. The purpose of this study is to select the tetraploid watermelon plants at M1 stage from populations applied colchicine and oryzaline with morphological anda cytological investigations in in vivo conditions. In this study, tetraploid plants belong to the four watermelon lines and diploid plants compared with the morphological and cytological dates. Morphological dates; width of the leaf-length (cm, male flower diameter (mm, diameter-length of the ovary (mm, the female flower petal width and length (mm were measured. Cytological assessment of the stoma diameter (μm, stomatal length (μm, stomatal density and chloroplast number were measured. In the present study has shown that the tetraploid plants grow vigorously as compared to diploid plants. Tetraploid plants are the number of chloroplasts increased, but decreased stomatal density were determined. As a result, tetraploid plants could be selected practically and economically by using morphological and cytological data for watermelon plants.

  5. Morphological Characterization and Determination of Aflatoxin-Production Potentials of Aspergillus flavus Isolated from Maize and Soil in Kenya

    OpenAIRE

    Matome Gabriel Thathana; Hunja Murage; Akebe Luther King Abia; Michael Pillay

    2017-01-01

    This study aimed at morphologically identifying Aspergillus flavus in soil and maize and at determining their aflatoxin-producing potentials. Five hundred and fourteen isolates obtained from maize and soil in Kenya were cultivated on Czapeck Dox Agar, Malt Extract Agar, Sabouraud Dextrose Agar, Potato Dextrose Agar, and Rose-Bengal Chloramphenicol Agar. Isolates were identified using macro-morphological characteristics. Micromorphological characteristics were determined using slide cultures. ...

  6. Dynamic structural disorder in supported nanoscale catalysts

    International Nuclear Information System (INIS)

    Rehr, J. J.; Vila, F. D.

    2014-01-01

    We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale

  7. Dynamic structural disorder in supported nanoscale catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rehr, J. J.; Vila, F. D. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

    2014-04-07

    We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.

  8. Nanomaterial Case Studies: Nanoscale Titanium Dioxide in ...

    Science.gov (United States)

    EPA announced the availability of the final report, Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen. This report is a starting point to determine what is known and what needs to be known about selected nanomaterials as part of a process to identify and prioritize research to inform future assessments of the potential ecological and health implications of these materials. Two specific applications of nanoscale titanium dioxide (nano-TiO2) are considered: (1) as an agent for removing arsenic from drinking water; and (2) as an active ingredient in topical sunscreen. These case studies are organized around a comprehensive environmental assessment (CEA) framework that combines a product life cycle perspective with the risk assessment paradigm. They are intended to help identify what may need to be known in order to conduct a comprehensive environmental assessment of the potential risks related to nano-TiO2. These “case studies” do not represent completed or even preliminary assessments, nor are they intended to serve as a basis for risk management decisions in the near term on these specific uses of nano TiO2. Rather, the intent is to use this document in developing the scientific and technical information needed for future assessment efforts.

  9. Understanding Solvent Manipulation of Morphology in Bulk-Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Chen, Yuxia; Zhan, Chuanlang; Yao, Jiannian

    2016-10-06

    Film morphology greatly influences the performance of bulk-heterojunction (BHJ)-structure-based solar cells. It is known that an interpenetrating bicontinuous network with nanoscale-separated donor and acceptor phases for charge transfer, an ordered molecular packing for exciton diffusion and charge transport, and a vertical compositionally graded structure for charge collection are prerequisites for achieving highly efficient BHJ organic solar cells (OSCs). Therefore, control of the morphology to obtain an ideal structure is a key problem. For this solution-processing BHJ system, the solvent participates fully in film processing. Its involvement is critical in modifying the nanostructure of BHJ films. In this review, we discuss the effects of solvent-related methods on the morphology of BHJ films, including selection of the casting solvent, solvent mixture, solvent vapor annealing, and solvent soaking. On the basis of a discussion on interaction strength and time between solvent and active materials, we believe that the solvent-morphology-performance relationship will be clearer and that solvent selection as a means to manipulate the morphology of BHJ films will be more rational. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Nanoscale Rheology and Anisotropic Diffusion Using Single Gold Nanorod Probes

    Science.gov (United States)

    Molaei, Mehdi; Atefi, Ehsan; Crocker, John C.

    2018-03-01

    The complex rotational and translational Brownian motion of anisotropic particles depends on their shape and the viscoelasticity of their surroundings. Because of their strong optical scattering and chemical versatility, gold nanorods would seem to provide the ultimate probes of rheology at the nanoscale, but the suitably accurate orientational tracking required to compute rheology has not been demonstrated. Here we image single gold nanorods with a laser-illuminated dark-field microscope and use optical polarization to determine their three-dimensional orientation to better than one degree. We convert the rotational diffusion of single nanorods in viscoelastic polyethylene glycol solutions to rheology and obtain excellent agreement with bulk measurements. Extensions of earlier models of anisotropic translational diffusion to three dimensions and viscoelastic fluids give excellent agreement with the observed motion of single nanorods. We find that nanorod tracking provides a uniquely capable approach to microrheology and provides a powerful tool for probing nanoscale dynamics and structure in a range of soft materials.

  11. Scanning transmission x-ray microscopy of polymer nanoparticles: probing morphology on sub-10 nm length scales.

    Science.gov (United States)

    Burke, Kerry B; Stapleton, Andrew J; Vaughan, Ben; Zhou, Xiaojing; Kilcoyne, A L David; Belcher, Warwick J; Dastoor, Paul C

    2011-07-01

    Water-processable nanoparticle dispersions of semiconducting polymers offer an attractive approach to the fabrication of organic electronic devices since they offer: (1) control of nanoscale morphology and (2) environmentally friendly fabrication. Although the nature of phase segregation in these polymer nanoparticles is critical to device performance, to date there have been no techniques available to directly determine their intra-particle structure, which consequently has been poorly understood. Here, we present scanning transmission x-ray microscopy (STXM) compositional maps for nanoparticles fabricated from poly(9,9-dioctyl-fluorene-2,7-diyl-co-bis-N, N'-(4-butylphenyl)-bis-N, N'-phenyl-1,4-phenylenedi-amine) (PFB) and poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (F8BT) 1:1 blend mixtures. The images show distinct phase segregation within the nanoparticles. The compositional data reveals that, within these nanoparticles, PFB and F8BT segregate into a core-shell morphology, with an F8BT-rich core and a PFB-rich shell. Structural modelling demonstrates that the STXM technique is capable of quantifying morphological features on a sub-10 nm length scale; below the spot size of the incident focused x-ray beam. These results have important implications for the development of water-based 'solar paints' fabricated from microemulsions of semiconducting polymers.

  12. Scanning transmission x-ray microscopy of polymer nanoparticles: probing morphology on sub-10 nm length scales

    Science.gov (United States)

    Burke, Kerry B.; Stapleton, Andrew J.; Vaughan, Ben; Zhou, Xiaojing; Kilcoyne, A. L. David; Belcher, Warwick J.; Dastoor, Paul C.

    2011-07-01

    Water-processable nanoparticle dispersions of semiconducting polymers offer an attractive approach to the fabrication of organic electronic devices since they offer: (1) control of nanoscale morphology and (2) environmentally friendly fabrication. Although the nature of phase segregation in these polymer nanoparticles is critical to device performance, to date there have been no techniques available to directly determine their intra-particle structure, which consequently has been poorly understood. Here, we present scanning transmission x-ray microscopy (STXM) compositional maps for nanoparticles fabricated from poly(9,9-dioctyl-fluorene-2,7-diyl-co-bis-N, N'-(4-butylphenyl)-bis-N, N'-phenyl-1,4-phenylenedi-amine) (PFB) and poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (F8BT) 1:1 blend mixtures. The images show distinct phase segregation within the nanoparticles. The compositional data reveals that, within these nanoparticles, PFB and F8BT segregate into a core-shell morphology, with an F8BT-rich core and a PFB-rich shell. Structural modelling demonstrates that the STXM technique is capable of quantifying morphological features on a sub-10 nm length scale; below the spot size of the incident focused x-ray beam. These results have important implications for the development of water-based 'solar paints' fabricated from microemulsions of semiconducting polymers.

  13. Scanning transmission x-ray microscopy of polymer nanoparticles: probing morphology on sub-10 nm length scales

    International Nuclear Information System (INIS)

    Burke, Kerry B; Stapleton, Andrew J; Vaughan, Ben; Zhou Xiaojing; Belcher, Warwick J; Dastoor, Paul C; Kilcoyne, A L David

    2011-01-01

    Water-processable nanoparticle dispersions of semiconducting polymers offer an attractive approach to the fabrication of organic electronic devices since they offer: (1) control of nanoscale morphology and (2) environmentally friendly fabrication. Although the nature of phase segregation in these polymer nanoparticles is critical to device performance, to date there have been no techniques available to directly determine their intra-particle structure, which consequently has been poorly understood. Here, we present scanning transmission x-ray microscopy (STXM) compositional maps for nanoparticles fabricated from poly(9,9-dioctyl-fluorene-2,7-diyl-co-bis-N, N ' -(4-butylphenyl)-bis-N, N ' -phenyl-1,4-phenylenedi-amine) (PFB) and poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (F8BT) 1:1 blend mixtures. The images show distinct phase segregation within the nanoparticles. The compositional data reveals that, within these nanoparticles, PFB and F8BT segregate into a core-shell morphology, with an F8BT-rich core and a PFB-rich shell. Structural modelling demonstrates that the STXM technique is capable of quantifying morphological features on a sub-10 nm length scale; below the spot size of the incident focused x-ray beam. These results have important implications for the development of water-based 'solar paints' fabricated from microemulsions of semiconducting polymers.

  14. Nano rough micron patterned titanium for directing osteoblast morphology and adhesion

    Directory of Open Access Journals (Sweden)

    Sabrina Puckett

    2008-06-01

    Full Text Available Sabrina Puckett, Rajesh Pareta, Thomas J WebsterDivision of Engineering, Brown University, Providence, RI, USAAbstract: Previous studies have demonstrated greater functions of osteoblasts (bone-forming cells on nanophase compared with conventional metals. Nanophase metals possess a biologically inspired nanostructured surface that mimics the dimensions of constituent components in bone, including collagen and hydroxyapatite. Not only do these components possess dimensions on the nanoscale, they are aligned in a parallel manner creating a defined orientation in bone. To date, research has yet to evaluate the effect that organized nanosurface features can have on the interaction of osteoblasts with material surfaces. Therefore, to determine if surface orientation of features can mediate osteoblast adhesion and morphology, this study investigated osteoblast function on patterned titanium substrates containing alternating regions of micron rough and nano rough surfaces prepared by novel electron beam evaporation techniques. This study was also interested in determining whether or not the size of the patterned regions had an effect on osteoblast behavior and alignment. Results indicated early controlled osteoblast alignment on these patterned materials as well as greater osteoblast adhesion on the nano rough regions of these patterned substrates. Interestingly, decreasing the width of the nano rough regions (from 80 µm to 22 µm on these patterned substrates resulted in a decreased number of osteoblasts adhering to these areas. Changes in the width of the nano rough regions also resulted in changes in osteoblast morphology, thus, suggesting there is an optimal pattern dimension that osteoblasts prefer. In summary, results of this study provided evidence that aligned nanophase metal features on the surface of titanium improved early osteoblast functions (morphology and adhesion promising for their long term functions, criteria necessary to improve

  15. Dopant atoms as quantum components in silicon nanoscale devices

    Science.gov (United States)

    Zhao, Xiaosong; Han, Weihua; Wang, Hao; Ma, Liuhong; Li, Xiaoming; Zhang, Wang; Yan, Wei; Yang, Fuhua

    2018-06-01

    Recent progress in nanoscale fabrication allows many fundamental studies of the few dopant atoms in various semiconductor nanostructures. Since the size of nanoscale devices has touched the limit of the nature, a single dopant atom may dominate the performance of the device. Besides, the quantum computing considered as a future choice beyond Moore's law also utilizes dopant atoms as functional units. Therefore, the dopant atoms will play a significant role in the future novel nanoscale devices. This review focuses on the study of few dopant atoms as quantum components in silicon nanoscale device. The control of the number of dopant atoms and unique quantum transport characteristics induced by dopant atoms are presented. It can be predicted that the development of nanoelectronics based on dopant atoms will pave the way for new possibilities in quantum electronics. Project supported by National Key R&D Program of China (No. 2016YFA0200503).

  16. In situ characterization of nanoscale catalysts during anodic redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  17. Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen (Final)

    Science.gov (United States)

    EPA announced the availability of the final report, Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen. This report is a starting point to determine what is known and what needs to be known about selected nanomaterials as par...

  18. Surface morphology effects on the light-controlled wettability of ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Khranovskyy, V., E-mail: volkh@ifm.liu.se [Department of Physics, Chemistry and Biology (IFM), Linkoping University (Sweden); Ekblad, T.; Yakimova, R.; Hultman, L. [Department of Physics, Chemistry and Biology (IFM), Linkoping University (Sweden)

    2012-08-01

    ZnO nanostructures of diverse morphology with shapes of corrals and cabbages as well as open and filled hexagons and sheaves prepared by APMOCVD technique, are investigated with water contact angle (CA) analysis. The as-grown ZnO nanostructures exhibit pure hydrophobic behavior, which is enhanced with the increase of the nanostructure's surface area. The most hydrophobic structures (CA = 124 Degree-Sign ) were found to be the complex nanosheaf, containing both the macro-and nanoscale features. It is concluded that the nanoscale roughness contributes significantly to the hydrophobicity increase. The character of wettability was possible to switch from hydrophobic-to-superhydrophilic state upon ultra violet irradiation. Both the rate and amplitude of the contact angle depend on the characteristic size of nanostructure. The observed effect is explained due to the semiconductor properties of zinc oxide enhanced by increased surface chemistry effect in nanostructures.

  19. Ellipsometry at the nanoscale

    CERN Document Server

    Hingerl, Kurt

    2013-01-01

    This book presents and introduces ellipsometry in nanoscience and nanotechnology making a bridge between the classical and nanoscale optical behaviour of materials. It delineates the role of the non-destructive and non-invasive optical diagnostics of ellipsometry in improving science and technology of nanomaterials and related processes by illustrating its exploitation, ranging from fundamental studies of the physics and chemistry of nanostructures to the ultimate goal of turnkey manufacturing control. This book is written for a broad readership: materials scientists, researchers, engineers, as well as students and nanotechnology operators who want to deepen their knowledge about both basics and applications of ellipsometry to nanoscale phenomena. It starts as a general introduction for people curious to enter the fields of ellipsometry and polarimetry applied to nanomaterials and progresses to articles by experts on specific fields that span from plasmonics, optics, to semiconductors and flexible electronics...

  20. Grazing incidence x-ray diffraction at free-standing nanoscale islands: fine structure of diffuse scattering

    International Nuclear Information System (INIS)

    Grigoriev, D; Hanke, M; Schmidbauer, M; Schaefer, P; Konovalov, O; Koehler, R

    2003-01-01

    We have investigated the x-ray intensity distribution around 220 reciprocal lattice point in case of grazing incidence diffraction at SiGe nanoscale free-standing islands grown on Si(001) substrate by LPE. Experiments and computer simulations based on the distorted wave Born approximation utilizing the results of elasticity theory obtained by FEM modelling have been carried out. The data reveal fine structure in the distribution of scattered radiation with well-pronounced maxima and complicated fringe pattern. Explanation of the observed diffraction phenomena in their relation to structure and morphology of the island is given. An optimal island model including its shape, size and Ge spatial distribution was elaborated

  1. Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

    KAUST Repository

    Verploegen, Eric; Miller, Chad E.; Schmidt, Kristin; Bao, Zhenan; Toney, Michael F.

    2012-01-01

    Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

  2. Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

    KAUST Repository

    Verploegen, Eric

    2012-10-23

    Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

  3. Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology

    Energy Technology Data Exchange (ETDEWEB)

    Ruberu, T. Purnima A.; Albright, Haley R.; Callis, Brandon; Ward, Brittney; Cisneros, Joana; Fan, Hua-Jun; Vela, Javier

    2012-04-22

    We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS–CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine–chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR (31P and 77Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine–chalcogenide precursor reactivity increases in the order: TPPE < DPPE < TBPE < TOPE < HPTE (E = S, Se). For a given phosphine, the selenide is always more reactive than the sulfide. CdS1–xSex quantum dots were synthesized via single injection of a R3PS–R3PSe mixture to cadmium oleate at 250 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R3PS and R3PSe reactivity dictates CdS1–xSex dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS1–xSex quantum rods were synthesized by injection of a single R3PE (E = S or Se) precursor or a R3PS–R3PSe mixture to cadmium–phosphonate at 320 or 250 °C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R3PE precursor reactivity. Purposely matching or mismatching R3PS–R3PSe precursor reactivity leads to CdS1–xSex nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable “bottom-up” programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications.

  4. Frontier in nanoscale flows fractional calculus and analytical methods

    CERN Document Server

    Lewis, Roland; Liu, Hong-yan

    2014-01-01

    This ebook covers the basic properties of nanoscale flows, and various analytical and numerical methods for nanoscale flows and environmental flows. This ebook is a good reference not only for audience of the journal, but also for various communities in mathematics, nanotechnology and environmental science.

  5. Fast heat flux modulation at the nanoscale

    OpenAIRE

    van Zwol, P. J.; Joulain, K.; Abdallah, P. Ben; Greffet, J. J.; Chevrier, J.

    2011-01-01

    We introduce a new concept for electrically controlled heat flux modulation. A flux contrast larger than 10 dB is expected with switching time on the order of tens of nanoseconds. Heat flux modulation is based on the interplay between radiative heat transfer at the nanoscale and phase change materials. Such large contrasts are not obtainable in solids, or in far field. As such this opens up new horizons for temperature modulation and actuation at the nanoscale.

  6. Evolution of nanodot morphology on polycarbonate (PC) surfaces by 40 keV Ar"+

    International Nuclear Information System (INIS)

    Goyal, Meetika; Chawla, Mahak; Gupta, Divya; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev

    2016-01-01

    In the present paper we have discussed the effect of 40 keV Ar"+ ions irradiation on nanoscale surface morphology of Polycarbonate (PC) substrate. Specimens were sputtered at off normal incidences of 30°, 40° and 50° with the fluence of 1 × 10"1"6 Ar"+cm"−"2. The topographical behaviour of specimens was studied by using Atomic Force Microscopy (AFM) technique. AFM study demonstrates the evolution of nano dot morphology on PC specimens on irradiating with 1 × 10"1"6 Ar"+cm"−"2. Average size of dots varied from 37-95 nm in this specified range of incidence while density of dots varied from 0.17-3.0 × 107 dotscm"−"2. Such variations in morphological features have been supported by estimation of ion range and sputtering yield through SRIM simulations.

  7. Nanoscale phase-change materials and devices

    International Nuclear Information System (INIS)

    Zheng, Qinghui; Wang, Yuxi; Zhu, Jia

    2017-01-01

    Phase-change materials (PCMs) that can reversibly transit between crystalline and amorphous phases have been widely used for data-storage and other functional devices. As PCMs scale down to nanoscale, the properties and transition procedures can vary, bringing both challenges and opportunities in scalability. This article describes the physical structures, properties and applications of nanoscale phase-change materials and devices. The limitations and performance of scaling properties in phase-change materials and the recent progress and challenges in phase-change devices are presented. At the end, some emerging applications related to phase-change materials are also introduced. (topical review)

  8. Nanoscale phase-change materials and devices

    Science.gov (United States)

    Zheng, Qinghui; Wang, Yuxi; Zhu, Jia

    2017-06-01

    Phase-change materials (PCMs) that can reversibly transit between crystalline and amorphous phases have been widely used for data-storage and other functional devices. As PCMs scale down to nanoscale, the properties and transition procedures can vary, bringing both challenges and opportunities in scalability. This article describes the physical structures, properties and applications of nanoscale phase-change materials and devices. The limitations and performance of scaling properties in phase-change materials and the recent progress and challenges in phase-change devices are presented. At the end, some emerging applications related to phase-change materials are also introduced.

  9. The role of apical contractility in determining cell morphology in multilayered epithelial sheets and tubes

    Science.gov (United States)

    Zhen Tan, Rui; Lai, Tanny; Chiam, K.-H.

    2017-08-01

    A multilayered epithelium is made up of individual cells that are stratified in an orderly fashion, layer by layer. In such tissues, individual cells can adopt a wide range of shapes ranging from columnar to squamous. From histological images, we observe that, in flat epithelia such as the skin, the cells in the top layer are squamous while those in the middle and bottom layers are columnar, whereas in tubular epithelia, the cells in all layers are columnar. We develop a computational model to understand how individual cell shape is governed by the mechanical forces within multilayered flat and curved epithelia. We derive the energy function for an epithelial sheet of cells considering intercellular adhesive and intracellular contractile forces. We determine computationally the cell morphologies that minimize the energy function for a wide range of cellular parameters. Depending on the dominant adhesive and contractile forces, we find four dominant cell morphologies for the multilayered-layered flat sheet and three dominant cell morphologies for the two-layered curved sheet. We study the transitions between the dominant cell morphologies for the two-layered flat sheet and find both continuous and discontinuous transitions and also the presence of multistable states. Matching our computational results with histological images, we conclude that apical contractile forces from the actomyosin belt in the epithelial cells is the dominant force determining cell shape in multilayered epithelia. Our computational model can guide tissue engineers in designing artificial multilayered epithelia, in terms of figuring out the cellular parameters needed to achieve realistic epithelial morphologies.

  10. [Determination of total mass and morphology analysis of heavy metal in soil with potassium biphthalate-sodium hydroxide by ICP-AES].

    Science.gov (United States)

    Qu, Jiao; Yuan, Xing; Cong, Qiao; Wang, Shuang

    2008-11-01

    Blank soil was used as quality controlling samples, soil sample dealt by potassium biphthalate-sodium hydroxide buffer solution was used as check sample, mixed acid HNO3-HF-HClO4 was chosen to nitrify soil samples, and plasma emission spectrometer (ICP-AES) was used as detecting method. The authors determined the total metal mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the extracted and dealt soil samples, and determined the mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the three chemical morphologies, including acid extractable morphology, oxide associated morphology, and organics associated modality. The experimental results indicated that the different pH of potassium biphthalate-sodium hydroxide buffer solution had obvious influence on the total mass of heavy metal and morphology transformation. Except for metal element Pb and Zn, the addition of different pH potassium dihydrogen phosphate-sodium hydroxide buffer solution could accelerate the soil samples nitrification and the total mass determination of heavy metal in the soil samples. The potassium biphthalate-sodium hydroxide buffer solution could facilitate the acid extractable morphology of Cr, Cu, Hg and Pb, oxidation associated morphology of As, Hg, Pb and Zn and the organic associated morphology transforming of As and Hg. At pH 5.8, the maximum acid extractable morphology contents of Cu and Hg were 2.180 and 0.632 mg x kg(-1), respectively; at pH 6.2, the maximal oxidation associated morphology content of Pb could achieve 27.792 mg x kg(-1); at pH 6.0, the maximum organic associated morphology content of heavy metal Hg was 4.715 mg x kg(-1).

  11. Trends in nanoscale mechanics mechanics of carbon nanotubes, graphene, nanocomposites and molecular dynamics

    CERN Document Server

    2014-01-01

    This book contains a collection of the state-of-the-art reviews written by the leading researchers in the areas of nanoscale mechanics, molecular dynamics, nanoscale modeling of nanocomposites and mechanics of carbon nanotubes. No other book has reviews of the recent discoveries such as a nanoscale analog of the Pauli’s principle, i.e., effect of the spatial exclusion of electrons or the SEE effect, a new Registry Matrix Analysis for the nanoscale interfacial sliding and new data on the effective viscosity of interfacial electrons in nanoscale stiction at the interfaces. This volume is also an exceptional resource on the well tested nanoscale modeling of carbon nanotubes and nanocomposites, new nanoscale effects, unique evaluations of the effective thickness of carbon nanotubes under different loads, new data on which size of carbon nanotubes is safer and many other topics. Extensive bibliography concerning all these topics is included along with the lucid short reviews. Numerous illustrations are provided...

  12. Democratization of Nanoscale Imaging and Sensing Tools Using Photonics.

    Science.gov (United States)

    McLeod, Euan; Wei, Qingshan; Ozcan, Aydogan

    2015-07-07

    Providing means for researchers and citizen scientists in the developing world to perform advanced measurements with nanoscale precision can help to accelerate the rate of discovery and invention as well as improve higher education and the training of the next generation of scientists and engineers worldwide. Here, we review some of the recent progress toward making optical nanoscale measurement tools more cost-effective, field-portable, and accessible to a significantly larger group of researchers and educators. We divide our review into two main sections: label-based nanoscale imaging and sensing tools, which primarily involve fluorescent approaches, and label-free nanoscale measurement tools, which include light scattering sensors, interferometric methods, photonic crystal sensors, and plasmonic sensors. For each of these areas, we have primarily focused on approaches that have either demonstrated operation outside of a traditional laboratory setting, including for example integration with mobile phones, or exhibited the potential for such operation in the near future.

  13. Heat transfer across the interface between nanoscale solids and gas.

    Science.gov (United States)

    Cheng, Chun; Fan, Wen; Cao, Jinbo; Ryu, Sang-Gil; Ji, Jie; Grigoropoulos, Costas P; Wu, Junqiao

    2011-12-27

    When solid materials and devices scale down in size, heat transfer from the active region to the gas environment becomes increasingly significant. We show that the heat transfer coefficient across the solid-gas interface behaves very differently when the size of the solid is reduced to the nanoscale, such as that of a single nanowire. Unlike for macroscopic solids, the coefficient is strongly pressure dependent above ∼10 Torr, and at lower pressures it is much higher than predictions of the kinetic gas theory. The heat transfer coefficient was measured between a single, free-standing VO(2) nanowire and surrounding air using laser thermography, where the temperature distribution along the VO(2) nanowire was determined by imaging its domain structure of metal-insulator phase transition. The one-dimensional domain structure along the nanowire results from the balance between heat generation by the focused laser and heat dissipation to the substrate as well as to the surrounding gas, and thus serves as a nanoscale power-meter and thermometer. We quantified the heat loss rate across the nanowire-air interface, and found that it dominates over all other heat dissipation channels for small-diameter nanowires near ambient pressure. As the heat transfer across the solid-gas interface is nearly independent of the chemical identity of the solid, the results reveal a general scaling relationship for gaseous heat dissipation from nanostructures of all solid materials, which is applicable to nanoscale electronic and thermal devices exposed to gaseous environments.

  14. Size effect on transfection and cytotoxicity of nanoscale plasmid DNA/polyethyleneimine complexes for aerosol gene delivery

    Energy Technology Data Exchange (ETDEWEB)

    Hoon Byeon, Jeong, E-mail: jbyeon@purdue.edu [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Kim, Jang-Woo, E-mail: jwkim@hoseo.edu [Department of Digital Display Engineering, Hoseo University, Asan 336-795 (Korea, Republic of)

    2014-02-03

    Nanoscale plasmid DNA (pDNA)/polyethyleneimine (PEI) complexes were fabricated in the aerosol state using a nebulization system consisting of a collison atomizer and a cool-walled diffusion dryer. The aerosol fabricated nanoscale complexes were collected and employed to determine fundamental properties of the complexes, such as size, structure, surface charge, and in vitro gene transfection efficiency and cytotoxicity. The results showed that mass ratio between pDNA and PEI should be optimized to enhance gene transfection efficiency without a significant loss of cell viability. These findings may support practical advancements in the field of nonviral gene delivery.

  15. Nanoscale-Agglomerate-Mediated Heterogeneous Nucleation.

    Science.gov (United States)

    Cha, Hyeongyun; Wu, Alex; Kim, Moon-Kyung; Saigusa, Kosuke; Liu, Aihua; Miljkovic, Nenad

    2017-12-13

    Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH 3 SH), dimethyl disulfide (CH 3 SSCH), and dimethyl trisulfide (CH 3 SSSCH 3 ) on the liquid-vapor interface during water vapor condensation, which act as preferential sites for heterogeneous nucleation after evaporation. The insights gained from this study elucidate fundamental aspects governing the behavior of both short- and long-term heterogeneous nucleation on hydrophobic surfaces, suggest previously unexplored microfabrication and air purification techniques, and present insights into the challenges facing the development of durable dropwise condensing surfaces.

  16. The Role of Isolation Methods on a Nanoscale Surface Structure and Its Effect on the Size of Exosomes

    Directory of Open Access Journals (Sweden)

    JungReem Woo

    2016-06-01

    Full Text Available Exosomes are ~100 nanometre diameter vesicles secreted by mammalian cells. These emerging disease biomarkers carry nucleic acids, proteins and lipids specific to the parental cells that secrete them. Exosomes are typically isolated in bulk by ultracentrifugation, filtration or immu‐ noaffinity precipitation for downstream proteomic, genomic, or lipidomic analysis. However, the structural properties and heterogeneity of isolated exosomes at the single vesicle level are not well characterized due to their small size. In this paper, by using high-resolution atomic force microscope imaging, we show the nanoscale mor‐ phology and structural heterogeneity in exosomes derived from U87 cells. Quantitative assessment of single exosomes reveals nanoscale variations in morphology, surface roughness and counts isolated by ultracentrifugation (UC and immunoaffinity (IA purification. Both methods produce intact globular, 30-120 nm sized vesicles when imaged under fluid and in air. However, IA exosomes had higher surface roughness and bimodal size population compared to UC exosomes. The study highlights the differences in size and surface topography of exosomes purified from a single cell type using different isolation methods.

  17. Uncovering Design Principles of Intermediate Filaments, a Self-Assembling Biomaterial: Lessons in Nanoscale Materials Design

    National Research Council Canada - National Science Library

    Lee, David H

    2007-01-01

    .... Such proteins may be harnessed for military purposes (eg. protective self-healing materials or nanoscale scaffolds) if one had a better understanding of how molecular structure determines material properties. In this final progress report, we summarize our studies on these systems.

  18. Morphology determination of small particles by electron microscopy and electrical conduction measurements

    International Nuclear Information System (INIS)

    Robrieux, B.; Desrousseaux, G.; Renou, A.; Gillet, M.

    1989-01-01

    In this paper, we show that it is possible to deduce the actual morphology of small particle condensed onto an insulator by combining the granularity analysis from electron micrographs and the electrical sheet conductance of the deposit on its substrate. Assuming the particles are truncated ellipsoids, we determine the excentricity and the contact angle with the substrate for Au on amorphous carbon and MgO substrates. (orig.)

  19. Nanoscale shape-memory alloys for ultrahigh mechanical damping.

    Science.gov (United States)

    San Juan, Jose; Nó, Maria L; Schuh, Christopher A

    2009-07-01

    Shape memory alloys undergo reversible transformations between two distinct phases in response to changes in temperature or applied stress. The creation and motion of the internal interfaces between these phases during such transformations dissipates energy, making these alloys effective mechanical damping materials. Although it has been shown that reversible phase transformations can occur in nanoscale volumes, it is not known whether these transformations have a sample size dependence. Here, we demonstrate that the two phases responsible for shape memory in Cu-Al-Ni alloys are more stable in nanoscale pillars than they are in the bulk. As a result, the pillars show a damping figure of merit that is substantially higher than any previously reported value for a bulk material, making them attractive for damping applications in nanoscale and microscale devices.

  20. Atomic nanoscale technology in the nuclear industry

    CERN Document Server

    Woo, Taeho

    2011-01-01

    Developments at the nanoscale are leading to new possibilities and challenges for nuclear applications in areas ranging from medicine to international commerce to atomic power production/waste treatment. Progress in nanotech is helping the nuclear industry slash the cost of energy production. It also continues to improve application reliability and safety measures, which remain a critical concern, especially since the reactor disasters in Japan. Exploring the new wide-ranging landscape of nuclear function, Atomic Nanoscale Technology in the Nuclear Industry details the breakthroughs in nanosca

  1. Introduction of Functional Structures in Nano-Scales into Engineering Polymer Films Using Radiation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Y., E-mail: maekawa.yasunari@jaea.go.jp [Japan Atomic Energy Agency (JAEA), Quantum Beam Science Directorate, High Performance Polymer Group, 1233 Watanuki-Machi, Takasaki, Gunma-ken 370-1292 (Japan)

    2010-07-01

    Introduction of functional regions in nanometer scale in polymeric films using γ-rays, EB, and ion beams are proposed. Two approaches to build nano-scale functional domains in polymer substrates are proposed: 1) Radiation-induced grafting to transfer nano-scale polymer crystalline structures (morphology), acting as a nano-template, to nano-scale graft polymer regions. The obtained polymers with nano structures can be applied to high performance polymer membranes. 2) Fabrication of nanopores and functional domains in engineering plastic films using ion beams, which deposit the energy in very narrow region of polymer films. Hydrophilic grafting polymers are introduced into hydrophobic fluorinated polymers, cross-linked PTFE (cPTFE) and aromatic hydrocarbon polymer, poly(ether ether ketone (PEEK), which is known to have lamella and crystallite in the polymer films. Then, the hierarchical structures of graft domains are analyzed by a small angle neutron scattering (SANS) experiment. From these analyses, the different structures and the different formation of graft domains were observed in fluorinated and hydrocarbon polymer substrates. the grafted domains in the cPTFE film, working as an ion channel, grew as covering the crystallite and the size of domain seems to be similar to that of crystallite. On the other hand, the PEEK-based PEM has a smaller domain size and it seems to grow independently on the crystallites of PEEK substrate. For nano-fabrication of polymer films using heavy ion beams, the energy distribution in radial direction, which is perpendicular to ion trajectory, is mainly concerned. For penumbra, we re-estimated effective radius of penumbra, in which radiation induced grafting took place, for several different ion beams. We observed the different diameters of the ion channels consisting of graft polymers. The channel sizes were quite in good agreement with the effective penumbra which possess the absorption doses more than 1 kGy. (author)

  2. Introduction of Functional Structures in Nano-Scales into Engineering Polymer Films Using Radiation Technique

    International Nuclear Information System (INIS)

    Maekawa, Y.

    2010-01-01

    Introduction of functional regions in nanometer scale in polymeric films using γ-rays, EB, and ion beams are proposed. Two approaches to build nano-scale functional domains in polymer substrates are proposed: 1) Radiation-induced grafting to transfer nano-scale polymer crystalline structures (morphology), acting as a nano-template, to nano-scale graft polymer regions. The obtained polymers with nano structures can be applied to high performance polymer membranes. 2) Fabrication of nanopores and functional domains in engineering plastic films using ion beams, which deposit the energy in very narrow region of polymer films. Hydrophilic grafting polymers are introduced into hydrophobic fluorinated polymers, cross-linked PTFE (cPTFE) and aromatic hydrocarbon polymer, poly(ether ether ketone (PEEK), which is known to have lamella and crystallite in the polymer films. Then, the hierarchical structures of graft domains are analyzed by a small angle neutron scattering (SANS) experiment. From these analyses, the different structures and the different formation of graft domains were observed in fluorinated and hydrocarbon polymer substrates. the grafted domains in the cPTFE film, working as an ion channel, grew as covering the crystallite and the size of domain seems to be similar to that of crystallite. On the other hand, the PEEK-based PEM has a smaller domain size and it seems to grow independently on the crystallites of PEEK substrate. For nano-fabrication of polymer films using heavy ion beams, the energy distribution in radial direction, which is perpendicular to ion trajectory, is mainly concerned. For penumbra, we re-estimated effective radius of penumbra, in which radiation induced grafting took place, for several different ion beams. We observed the different diameters of the ion channels consisting of graft polymers. The channel sizes were quite in good agreement with the effective penumbra which possess the absorption doses more than 1 kGy. (author)

  3. Osteogenic response of human mesenchymal stem cells to well-defined nanoscale topography in vitro

    Directory of Open Access Journals (Sweden)

    de Peppo GM

    2014-05-01

    Full Text Available Giuseppe Maria de Peppo,1–3 Hossein Agheli,2,3 Camilla Karlsson,2,3 Karin Ekström,2,3 Helena Brisby,3,4 Maria Lennerås,2,3 Stefan Gustafsson,3,5 Peter Sjövall,3,5,6 Anna Johansson,2,3 Eva Olsson,3,5 Jukka Lausmaa,3,6 Peter Thomsen,2,3 Sarunas Petronis3,6 1The New York Stem Cell Foundation Research Institute, New York, NY, USA; 2Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, 3BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, 4Department of Orthopaedics, Sahlgrenska Academy, University of Gothenburg, 5Applied Physics, Chalmers University of Technology, Göteborg, Sweden; 6Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Borås, Sweden Background: Patterning medical devices at the nanoscale level enables the manipulation of cell behavior and tissue regeneration, with topographic features recognized as playing a significant role in the osseointegration of implantable devices. Methods: In this study, we assessed the ability of titanium-coated hemisphere-like topographic nanostructures of different sizes (approximately 50, 100, and 200 nm to influence the morphology, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs. Results: We found that the proliferation and osteogenic differentiation of hMSCs was influenced by the size of the underlying structures, suggesting that size variations in topographic features at the nanoscale level, independently of chemistry, can be exploited to control hMSC behavior in a size-dependent fashion. Conclusion: Our studies demonstrate that colloidal lithography, in combination with coating technologies, can be exploited to investigate the cell response to well defined nanoscale topography and to develop next-generation surfaces that guide tissue regeneration and promote implant integration. Keywords: colloidal lithography, nanotopography, human mesenchymal stem cells, cell proliferation, osteogenic

  4. Investigation of Short Channel Effect on Vertical Structures in Nanoscale MOSFET

    Directory of Open Access Journals (Sweden)

    Munawar A. Riyadi

    2009-12-01

    Full Text Available The recent development of MOSFET demands innovative approach to maintain the scaling into nanoscale dimension. This paper focuses on the physical nature of vertical MOSFET in nanoscale regime. Vertical structure is one of the promising devices in further scaling, with relaxed-lithography feature in the manufacture. The comparison of vertical and lateral MOSFET performance for nanoscale channel length (Lch is demonstrated with the help of numerical tools. The evaluation of short channel effect (SCE parameters, i.e. threshold voltage roll-off, subthreshold swing (SS, drain induced barrier lowering (DIBL and leakage current shows the considerable advantages as well as its thread-off in implementing the structure, in particular for nanoscale regime.

  5. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

    2015-11-03

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  6. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  7. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2015-07-14

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  8. Temperature-dependent morphology of hybrid nanoflowers from elastin-like polypeptides

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Koushik; Balog, Eva Rose M.; Sista, Prakash; Williams, Darrick J.; Martinez, Jennifer S., E-mail: jenm@lanl.gov, E-mail: rcrocha@lanl.gov; Rocha, Reginaldo C., E-mail: jenm@lanl.gov, E-mail: rcrocha@lanl.gov [Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Kelly, Daniel [Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2014-02-01

    We report a method for creating hybrid organic-inorganic “nanoflowers” using calcium or copper ions as the inorganic component and a recombinantly expressed elastin-like polypeptide (ELP) as the organic component. Polypeptides provide binding sites for the dynamic coordination with metal ions, and then such noncovalent complexes become nucleation sites for primary crystals of metal phosphates. We have shown that the interaction between the stimuli-responsive ELP and Ca{sup 2+} or Cu{sup 2+}, in the presence of phosphate, leads to the growth of micrometer-sized particles featuring nanoscale patterns shaped like flower petals. The morphology of these flower-like composite structures is dependent upon the temperature of growth and has been characterized by scanning electron microscopy. The composition of nanoflowers has also been analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The temperature-dependent morphologies of these hybrid nanostructures, which arise from the controllable phase transition of ELPs, hold potential for morphological control of biomaterials in emerging applications such as tissue engineering and biocatalysis.

  9. Temperature-dependent morphology of hybrid nanoflowers from elastin-like polypeptides

    Directory of Open Access Journals (Sweden)

    Koushik Ghosh

    2014-02-01

    Full Text Available We report a method for creating hybrid organic-inorganic “nanoflowers” using calcium or copper ions as the inorganic component and a recombinantly expressed elastin-like polypeptide (ELP as the organic component. Polypeptides provide binding sites for the dynamic coordination with metal ions, and then such noncovalent complexes become nucleation sites for primary crystals of metal phosphates. We have shown that the interaction between the stimuli-responsive ELP and Ca2+ or Cu2+, in the presence of phosphate, leads to the growth of micrometer-sized particles featuring nanoscale patterns shaped like flower petals. The morphology of these flower-like composite structures is dependent upon the temperature of growth and has been characterized by scanning electron microscopy. The composition of nanoflowers has also been analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The temperature-dependent morphologies of these hybrid nanostructures, which arise from the controllable phase transition of ELPs, hold potential for morphological control of biomaterials in emerging applications such as tissue engineering and biocatalysis.

  10. Environmental determinism, and not interspecific competition, drives morphological variability in Australasian warblers (Acanthizidae).

    Science.gov (United States)

    García-Navas, Vicente; Rodríguez-Rey, Marta; Marki, Petter Z; Christidis, Les

    2018-04-01

    Interspecific competition is thought to play a key role in determining the coexistence of closely related species within adaptive radiations. Competition for ecological resources can lead to different outcomes from character displacement to, ultimately, competitive exclusion. Accordingly, divergent natural selection should disfavor those species that are the most similar to their competitor in resource use, thereby increasing morphological disparity. Here, we examined ecomorphological variability within an Australo-Papuan bird radiation, the Acanthizidae, which include both allopatric and sympatric complexes. In addition, we investigated whether morphological similarities between species are related to environmental factors at fine scale (foraging niche) and/or large scale (climate). Contrary to that predicted by the competition hypothesis, we did not find a significant correlation between the morphological similarities found between species and their degree of range overlap. Comparative modeling based on both a priori and data-driven identification of selective regimes suggested that foraging niche is a poor predictor of morphological variability in acanthizids. By contrast, our results indicate that climatic conditions were an important factor in the formation of morphological variation. We found a significant negative correlation between species scores for PC1 (positively associated to tarsus length and tail length) and both temperature and precipitation, whereas PC2 (positively associated to bill length and wing length) correlated positively with precipitation. In addition, we found that species inhabiting the same region are closer to each other in morphospace than to species outside that region regardless of genus to which they belong or its foraging strategy. Our results indicate that the conservative body form of acanthizids is one that can work under a wide variety of environments (an all-purpose morphology), and the observed interspecific similarity is

  11. Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator

    International Nuclear Information System (INIS)

    Suto, Hirofumi; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

    2014-01-01

    Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet. (papers)

  12. Quantum mechanical modeling the emission pattern and polarization of nanoscale light emitting diodes.

    Science.gov (United States)

    Wang, Rulin; Zhang, Yu; Bi, Fuzhen; Frauenheim, Thomas; Chen, GuanHua; Yam, ChiYung

    2016-07-21

    Understanding of the electroluminescence (EL) mechanism in optoelectronic devices is imperative for further optimization of their efficiency and effectiveness. Here, a quantum mechanical approach is formulated for modeling the EL processes in nanoscale light emitting diodes (LED). Based on non-equilibrium Green's function quantum transport equations, interactions with the electromagnetic vacuum environment are included to describe electrically driven light emission in the devices. The presented framework is illustrated by numerical simulations of a silicon nanowire LED device. EL spectra of the nanowire device under different bias voltages are obtained and, more importantly, the radiation pattern and polarization of optical emission can be determined using the current approach. This work is an important step forward towards atomistic quantum mechanical modeling of the electrically induced optical response in nanoscale systems.

  13. Topology optimization for nano-scale heat transfer

    DEFF Research Database (Denmark)

    Evgrafov, Anton; Maute, Kurt; Yang, Ronggui

    2009-01-01

    We consider the problem of optimal design of nano-scale heat conducting systems using topology optimization techniques. At such small scales the empirical Fourier's law of heat conduction no longer captures the underlying physical phenomena because the mean-free path of the heat carriers, phonons...... in our case, becomes comparable with, or even larger than, the feature sizes of considered material distributions. A more accurate model at nano-scales is given by kinetic theory, which provides a compromise between the inaccurate Fourier's law and precise, but too computationally expensive, atomistic...

  14. Direct Probing of Polarization Charge at Nanoscale Level

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Owoong [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Seol, Daehee [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering; Lee, Dongkyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Han, Hee [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Lindfors-Vrejoiu, Ionela [Univ. of Cologne (Germany). Physics Inst.; Lee, Woo [Korea Research Inst. of Standards and Science (KRISS), Daejeon (South Korea); Jesse, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Lee, Ho Nyung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences; Alexe, Marin [Univ. of Warwick, Coventry (United Kingdom). Dept. of Physics; Kim, Yunseok [Sungkyunkwan Univ., Suwon (Republic of Korea). School of Advanced Materials and Engineering

    2017-11-14

    Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. In order to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio. But, the detection is unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive-up-negative-down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm-2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The results we obtained show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale.

  15. Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (Final Report)

    Science.gov (United States)

    EPA announced the release of the final report, Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray. This report represents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant spr...

  16. Investigating Nanoscale Electrochemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Zaleski, Stephanie; Wilson, Andrew J; Mattei, Michael; Chen, Xu; Goubert, Guillaume; Cardinal, M Fernanda; Willets, Katherine A; Van Duyne, Richard P

    2016-09-20

    The chemical sensitivity of surface-enhanced Raman spectroscopy (SERS) methodologies allows for the investigation of heterogeneous chemical reactions with high sensitivity. Specifically, SERS methodologies are well-suited to study electron transfer (ET) reactions, which lie at the heart of numerous fundamental processes: electrocatalysis, solar energy conversion, energy storage in batteries, and biological events such as photosynthesis. Heterogeneous ET reactions are commonly monitored by electrochemical methods such as cyclic voltammetry, observing billions of electrochemical events per second. Since the first proof of detecting single molecules by redox cycling, there has been growing interest in examining electrochemistry at the nanoscale and single-molecule levels. Doing so unravels details that would otherwise be obscured by an ensemble experiment. The use of optical spectroscopies, such as SERS, to elucidate nanoscale electrochemical behavior is an attractive alternative to traditional approaches such as scanning electrochemical microscopy (SECM). While techniques such as single-molecule fluorescence or electrogenerated chemiluminescence have been used to optically monitor electrochemical events, SERS methodologies, in particular, have shown great promise for exploring electrochemistry at the nanoscale. SERS is ideally suited to study nanoscale electrochemistry because the Raman-enhancing metallic, nanoscale substrate duly serves as the working electrode material. Moreover, SERS has the ability to directly probe single molecules without redox cycling and can achieve nanoscale spatial resolution in combination with super-resolution or scanning probe microscopies. This Account summarizes the latest progress from the Van Duyne and Willets groups toward understanding nanoelectrochemistry using Raman spectroscopic methodologies. The first half of this Account highlights three techniques that have been recently used to probe few- or single-molecule electrochemical

  17. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  18. Fabrication and Characterization of Polymeric Hollow Fiber Membranes with Nano-scale Pore Sizes

    International Nuclear Information System (INIS)

    Amir Mansourizadeh; Ahmad Fauzi Ismail

    2011-01-01

    Porous polyvinylidene fluoride (PVDF) and polysulfide (PSF) hollow fiber membranes were fabricated via a wet spinning method. The membranes were characterized in terms of gas permeability, wetting pressure, overall porosity and water contact angle. The morphology of the membranes was examined by FESEM. From gas permeation test, mean pore sizes of 7.3 and 9.6 nm were obtained for PSF and PVDF membrane, respectively. Using low polymer concentration in the dopes, the membranes demonstrated a relatively high overall porosity of 77 %. From FESEM examination, the PSF membrane presented a denser outer skin layer, which resulted in significantly lower N 2 permeance. Therefore, due to the high hydrophobicity and nano-scale pore sizes of the PVDF membrane, a good wetting pressure of 4.5x10 -5 Pa was achieved. (author)

  19. Correlative FRET: new method improves rigor and reproducibility in determining distances within synaptic nanoscale architecture

    Science.gov (United States)

    Shinogle-Decker, Heather; Martinez-Rivera, Noraida; O'Brien, John; Powell, Richard D.; Joshi, Vishwas N.; Connell, Samuel; Rosa-Molinar, Eduardo

    2018-02-01

    A new correlative Förster Resonance Energy Transfer (FRET) microscopy method using FluoroNanogold™, a fluorescent immunoprobe with a covalently attached Nanogold® particle (1.4nm Au), overcomes resolution limitations in determining distances within synaptic nanoscale architecture. FRET by acceptor photobleaching has long been used as a method to increase fluorescence resolution. The transfer of energy from a donor to an acceptor generally occurs between 10-100Å, which is the relative distance between the donor molecule and the acceptor molecule. For the correlative FRET microscopy method using FluoroNanogold™, we immuno-labeled GFP-tagged-HeLa-expressing Connexin 35 (Cx35) with anti-GFP and with anti-Cx35/36 antibodies, and then photo-bleached the Cx before processing the sample for electron microscopic imaging. Preliminary studies reveal the use of Alexa Fluor® 594 FluoroNanogold™ slightly increases FRET distance to 70Å, in contrast to the 62.5Å using AlexaFluor 594®. Preliminary studies also show that using a FluoroNanogold™ probe inhibits photobleaching. After one photobleaching session, Alexa Fluor 594® fluorescence dropped to 19% of its original fluorescence; in contrast, after one photobleaching session, Alexa Fluor 594® FluoroNanogold™ fluorescence dropped to 53% of its original intensity. This result confirms that Alexa Fluor 594® FluoroNanogold™ is a much better donor probe than is Alexa Fluor 594®. The new method (a) creates a double confirmation method in determining structure and orientation of synaptic architecture, (b) allows development of a two-dimensional in vitro model to be used for precise testing of multiple parameters, and (c) increases throughput. Future work will include development of FluoroNanogold™ probes with different sizes of gold for additional correlative microscopy studies.

  20. Scanning transmission x-ray microscopy of polymer nanoparticles: probing morphology on sub-10 nm length scales

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Kerry B; Stapleton, Andrew J; Vaughan, Ben; Zhou Xiaojing; Belcher, Warwick J; Dastoor, Paul C [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia); Kilcoyne, A L David, E-mail: Paul.Dastoor@newcastle.edu.au [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-07-01

    Water-processable nanoparticle dispersions of semiconducting polymers offer an attractive approach to the fabrication of organic electronic devices since they offer: (1) control of nanoscale morphology and (2) environmentally friendly fabrication. Although the nature of phase segregation in these polymer nanoparticles is critical to device performance, to date there have been no techniques available to directly determine their intra-particle structure, which consequently has been poorly understood. Here, we present scanning transmission x-ray microscopy (STXM) compositional maps for nanoparticles fabricated from poly(9,9-dioctyl-fluorene-2,7-diyl-co-bis-N, N{sup '}-(4-butylphenyl)-bis-N, N{sup '}-phenyl-1,4-phenylenedi-amine) (PFB) and poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (F8BT) 1:1 blend mixtures. The images show distinct phase segregation within the nanoparticles. The compositional data reveals that, within these nanoparticles, PFB and F8BT segregate into a core-shell morphology, with an F8BT-rich core and a PFB-rich shell. Structural modelling demonstrates that the STXM technique is capable of quantifying morphological features on a sub-10 nm length scale; below the spot size of the incident focused x-ray beam. These results have important implications for the development of water-based 'solar paints' fabricated from microemulsions of semiconducting polymers.

  1. Using mathematical models to understand the effect of nanoscale roughness on protein adsorption for improving medical devices

    Directory of Open Access Journals (Sweden)

    Ercan B

    2013-09-01

    Full Text Available Batur Ercan,1 Dongwoo Khang,2 Joseph Carpenter,3 Thomas J Webster1 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2School of Materials Science and Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South Korea; 3School of Medicine, Stanford University, Stanford, CA, USA Abstract: Surface roughness and energy significantly influence protein adsorption on to biomaterials, which, in turn, controls select cellular adhesion to determine the success and longevity of an implant. To understand these relationships at a fundamental level, a model was originally proposed by Khang et al to correlate nanoscale surface properties (specifically, nanoscale roughness and energy to protein adsorption, which explained the greater cellular responses on nanostructured surfaces commonly reported in the literature today. To test this model for different surfaces from what was previously used to develop that model, in this study we synthesized highly ordered poly(lactic-co-glycolic acid surfaces of identical chemistry but altered nanoscale surface roughness and energy using poly(dimethylsiloxane molds of polystyrene beads. Fibronectin and collagen type IV adsorption studies showed a linear adsorption behavior as the surface nanoroughness increased. This supported the general trends observed by Khang et al. However, when fitting such data to the mathematical model established by Khang et al, a strong correlation did not result. Thus, this study demonstrated that the equation proposed by Khang et al to predict protein adsorption should be modified to accommodate for additional nanoscale surface property contributions (ie, surface charge to make the model more accurate. In summary, results from this study provided an important step in developing future mathematical models that can correlate surface properties (such as nanoscale roughness and surface energy to initial protein adsorption events important to

  2. Carpel size, grain filling, and morphology determine individual grain weight in wheat

    OpenAIRE

    Xie, Quan; Mayes, Sean; Sparkes, Debbie L.

    2015-01-01

    Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)?spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulat...

  3. Nanoscale form dictates mesoscale function in plasmonic DNA–nanoparticle superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Michael B.; Ku, Jessie C.; Vaccarezza, Victoria M.; Schatz, George C.; Mirkin , Chad A. (NWU)

    2016-06-15

    The nanoscale manipulation of matter allows properties to be created in a material that would be difficult or even impossible to achieve in the bulk state. Progress towards such functional nanoscale architectures requires the development of methods to precisely locate nanoscale objects in three dimensions and for the formation of rigorous structure–function relationships across multiple size regimes (beginning from the nanoscale). Here, we use DNA as a programmable ligand to show that two- and three-dimensional mesoscale superlattice crystals with precisely engineered optical properties can be assembled from the bottom up. The superlattices can transition from exhibiting the properties of the constituent plasmonic nanoparticles to adopting the photonic properties defined by the mesoscale crystal (here a rhombic dodecahedron) by controlling the spacing between the gold nanoparticle building blocks. Furthermore, we develop a generally applicable theoretical framework that illustrates how crystal habit can be a design consideration for controlling far-field extinction and light confinement in plasmonic metamaterial superlattices.

  4. Nanoscale RRAM-based synaptic electronics: toward a neuromorphic computing device.

    Science.gov (United States)

    Park, Sangsu; Noh, Jinwoo; Choo, Myung-Lae; Sheri, Ahmad Muqeem; Chang, Man; Kim, Young-Bae; Kim, Chang Jung; Jeon, Moongu; Lee, Byung-Geun; Lee, Byoung Hun; Hwang, Hyunsang

    2013-09-27

    Efforts to develop scalable learning algorithms for implementation of networks of spiking neurons in silicon have been hindered by the considerable footprints of learning circuits, which grow as the number of synapses increases. Recent developments in nanotechnologies provide an extremely compact device with low-power consumption.In particular, nanoscale resistive switching devices (resistive random-access memory (RRAM)) are regarded as a promising solution for implementation of biological synapses due to their nanoscale dimensions, capacity to store multiple bits and the low energy required to operate distinct states. In this paper, we report the fabrication, modeling and implementation of nanoscale RRAM with multi-level storage capability for an electronic synapse device. In addition, we first experimentally demonstrate the learning capabilities and predictable performance by a neuromorphic circuit composed of a nanoscale 1 kbit RRAM cross-point array of synapses and complementary metal-oxide-semiconductor neuron circuits. These developments open up possibilities for the development of ubiquitous ultra-dense, ultra-low-power cognitive computers.

  5. Nanoscale RRAM-based synaptic electronics: toward a neuromorphic computing device

    International Nuclear Information System (INIS)

    Park, Sangsu; Noh, Jinwoo; Choo, Myung-lae; Sheri, Ahmad Muqeem; Jeon, Moongu; Lee, Byung-Geun; Lee, Byoung Hun; Chang, Man; Kim, Young-Bae; Kim, Chang Jung; Hwang, Hyunsang

    2013-01-01

    Efforts to develop scalable learning algorithms for implementation of networks of spiking neurons in silicon have been hindered by the considerable footprints of learning circuits, which grow as the number of synapses increases. Recent developments in nanotechnologies provide an extremely compact device with low-power consumption. In particular, nanoscale resistive switching devices (resistive random-access memory (RRAM)) are regarded as a promising solution for implementation of biological synapses due to their nanoscale dimensions, capacity to store multiple bits and the low energy required to operate distinct states. In this paper, we report the fabrication, modeling and implementation of nanoscale RRAM with multi-level storage capability for an electronic synapse device. In addition, we first experimentally demonstrate the learning capabilities and predictable performance by a neuromorphic circuit composed of a nanoscale 1 kbit RRAM cross-point array of synapses and complementary metal–oxide–semiconductor neuron circuits. These developments open up possibilities for the development of ubiquitous ultra-dense, ultra-low-power cognitive computers. (paper)

  6. Control of friction at the nanoscale

    Science.gov (United States)

    Barhen, Jacob; Braiman, Yehuda Y.; Protopopescu, Vladimir

    2010-04-06

    Methods and apparatus are described for control of friction at the nanoscale. A method of controlling frictional dynamics of a plurality of particles using non-Lipschitzian control includes determining an attribute of the plurality of particles; calculating an attribute deviation by subtracting the attribute of the plurality of particles from a target attribute; calculating a non-Lipschitzian feedback control term by raising the attribute deviation to a fractionary power .xi.=(2m+1)/(2n+1) where n=1, 2, 3 . . . and m=0, 1, 2, 3 . . . , with m strictly less than n and then multiplying by a control amplitude; and imposing the non-Lipschitzian feedback control term globally on each of the plurality of particles; imposing causes a subsequent magnitude of the attribute deviation to be reduced.

  7. Evolution of nanodot morphology on polycarbonate (PC) surfaces by 40 keV Ar{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Meetika, E-mail: meetika89@gmail.com; Chawla, Mahak; Gupta, Divya; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev [Department of Physics, Kurukshetra University, Kurukshetra - 136119 (India)

    2016-05-06

    In the present paper we have discussed the effect of 40 keV Ar{sup +} ions irradiation on nanoscale surface morphology of Polycarbonate (PC) substrate. Specimens were sputtered at off normal incidences of 30°, 40° and 50° with the fluence of 1 × 10{sup 16} Ar{sup +}cm{sup −2}. The topographical behaviour of specimens was studied by using Atomic Force Microscopy (AFM) technique. AFM study demonstrates the evolution of nano dot morphology on PC specimens on irradiating with 1 × 10{sup 16} Ar{sup +}cm{sup −2}. Average size of dots varied from 37-95 nm in this specified range of incidence while density of dots varied from 0.17-3.0 × 107 dotscm{sup −2}. Such variations in morphological features have been supported by estimation of ion range and sputtering yield through SRIM simulations.

  8. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  9. Bio-Conjugates for Nanoscale Applications

    DEFF Research Database (Denmark)

    Villadsen, Klaus

    Bio-conjugates for Nanoscale Applications is the title of this thesis, which covers three different projects in chemical bio-conjugation research, namely synthesis and applications of: Lipidated fluorescent peptides, carbohydrate oxime-azide linkers and N-aryl O-R2 oxyamine derivatives. Lipidated...

  10. Systems engineering at the nanoscale

    Science.gov (United States)

    Benkoski, Jason J.; Breidenich, Jennifer L.; Wei, Michael C.; Clatterbaughi, Guy V.; Keng, Pei Yuin; Pyun, Jeffrey

    2012-06-01

    Nanomaterials have provided some of the greatest leaps in technology over the past twenty years, but their relatively early stage of maturity presents challenges for their incorporation into engineered systems. Perhaps even more challenging is the fact that the underlying physics at the nanoscale often run counter to our physical intuition. The current state of nanotechnology today includes nanoscale materials and devices developed to function as components of systems, as well as theoretical visions for "nanosystems," which are systems in which all components are based on nanotechnology. Although examples will be given to show that nanomaterials have indeed matured into applications in medical, space, and military systems, no complete nanosystem has yet been realized. This discussion will therefore focus on systems in which nanotechnology plays a central role. Using self-assembled magnetic artificial cilia as an example, we will discuss how systems engineering concepts apply to nanotechnology.

  11. Exploring Ultimate Water Capillary Evaporation in Nanoscale Conduits.

    Science.gov (United States)

    Li, Yinxiao; Alibakhshi, Mohammad Amin; Zhao, Yihong; Duan, Chuanhua

    2017-08-09

    Capillary evaporation in nanoscale conduits is an efficient heat/mass transfer strategy that has been widely utilized by both nature and mankind. Despite its broad impact, the ultimate transport limits of capillary evaporation in nanoscale conduits, governed by the evaporation/condensation kinetics at the liquid-vapor interface, have remained poorly understood. Here we report experimental study of the kinetic limits of water capillary evaporation in two dimensional nanochannels using a novel hybrid channel design. Our results show that the kinetic-limited evaporation fluxes break down the limits predicated by the classical Hertz-Knudsen equation by an order of magnitude, reaching values up to 37.5 mm/s with corresponding heat fluxes up to 8500 W/cm 2 . The measured evaporation flux increases with decreasing channel height and relative humidity but decreases as the channel temperature decreases. Our findings have implications for further understanding evaporation at the nanoscale and developing capillary evaporation-based technologies for both energy- and bio-related applications.

  12. Determination of crack morphology parameters from service failures for leak-rate analyses

    Energy Technology Data Exchange (ETDEWEB)

    Wilkowski, G.; Ghadiali, N.; Paul, D. [Battelle Memorial Institute, Columbus, OH (United States)] [and others

    1997-04-01

    In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.

  13. Insights on the Study of Nafion Nanoscale Morphology by Transmission Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Sergey Yakovlev

    2013-12-01

    Full Text Available Nafion is one of the most common materials used for polyelectrolyte membranes and is the standard to which novel materials are compared. In spite of great interest in Nafion’s nanostructure, it is still a subject of controversy. While multiple research efforts have addressed Nafion’s morphology with Transmission Electron Microscopy, the results of these efforts have often been inconsistent and cannot satisfactorily describe the membrane structure. One of the reasons for differences in the reported results is the lack of sufficient control over the damage caused by electron beam irradiation. In this work, we describe some aspects of damage in the material that have a strong influence on the results. We show that irradiation causes mass loss and phase separation in the material and that the morphologies that have been observed are, in many cases, artifacts caused by damage. We study the effect of the sample temperature on damage and show that, while working at low temperature does not prevent damage and mass loss, it slows formation of damage-induced artifacts to the point where informative low-dose images of almost undamaged material may be collected. We find that charging of the sample has a substantial effect on the damage, and the importance of charge neutralization under irradiation is also seen by the large reduction of beam induced movement with the use of an objective aperture or a conductive support film. To help interpret the low-dose images, we can apply slightly higher exposures to etch away the hydrophobic phase with the electron beam and reveal the network formed by the hydrophilic phase. Energy loss spectroscopy shows evidence that fluorine removal governs the beam damage process.

  14. Synthesis, Morphologies and Building Applications of Nanostructured Polymers

    Directory of Open Access Journals (Sweden)

    Yong Lu

    2017-10-01

    Full Text Available Nanostructured polymers (NSPs are polymeric materials in the size of nanoscale, normally consisting of nanoparticles, nanofibers, nanowires, nanospheres and other morphologies. Polymer nanoparticles (PNPs can be fabricated either by physical methods (i.e., solvent evaporation, nanoprecipitation, salting out or by direct nanosynthesis, using micro- or nanoemulsions with nanoreactor compartments to perform polymerization. Polymer nanofibers (PNFs can be produced via various techniques and the most commonly used approach is electrospinning, whereby a charged solution of a polymer when exposed to an opposite high electric field is pulled into long thin nanofibers. NSPs in general exhibit enhanced properties such as excellent structural and mechanical properties, making them promising candidates for some particular building applications. A variety of PNFs have been developed and used for noise and air pollution filtration. Moreover, PNFs can also be fabricated with phase change materials which are usually employed for thermal energy storage in construction industry. In this review, we will summarize the morphologies and nanosynthesis methods of NSPs, in particular, PNPs and PNFs. In addition, representative NSPs mainly used in construction are introduced for building applications.

  15. Nano-Scale Positioning Design with Piezoelectric Materials

    Directory of Open Access Journals (Sweden)

    Yung Yue Chen

    2017-12-01

    Full Text Available Piezoelectric materials naturally possess high potential to deliver nano-scale positioning resolution; hence, they are adopted in a variety of engineering applications widely. Unfortunately, unacceptable positioning errors always appear because of the natural hysteresis effect of the piezoelectric materials. This natural property must be mitigated in practical applications. For solving this drawback, a nonlinear positioning design is proposed in this article. This nonlinear positioning design of piezoelectric materials is realized by the following four steps: 1. The famous Bouc–Wen model is utilized to present the input and output behaviors of piezoelectric materials; 2. System parameters of the Bouc–Wen model that describe the characteristics of piezoelectric materials are simultaneously identified with the particle swam optimization method; 3. Stability verification for the identified Bouc–Wen model; 4. A nonlinear feedback linearization control design is derived for the nano-scale positioning design of the piezoelectric material, mathematically. One important contribution of this investigation is that the positioning error between the output displacement of the controlled piezoelectric materials and the desired trajectory in nano-scale level can be proven to converge to zero asymptotically, under the effect of the hysteresis.

  16. Static electric field enhancement in nanoscale structures

    Energy Technology Data Exchange (ETDEWEB)

    Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)

    2016-08-28

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  17. Nanoscale chirality in metal and semiconductor nanoparticles.

    Science.gov (United States)

    Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

    2016-10-18

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

  18. Nanoscale thermal transport. II. 2003-2012

    Science.gov (United States)

    Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

    2014-03-01

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ˜ 1 nm , the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal

  19. Cell-specific STORM superresolution imaging reveals nanoscale organization of cannabinoid signaling

    Science.gov (United States)

    Szabó, Szilárd I.; Szabadits, Eszter; Pintér, Balázs; Woodhams, Stephen G.; Henstridge, Christopher M.; Balla, Gyula Y.; Nyilas, Rita; Varga, Csaba; Lee, Sang-Hun; Matolcsi, Máté; Cervenak, Judit; Kacskovics, Imre; Watanabe, Masahiko; Sagheddu, Claudia; Melis, Miriam; Pistis, Marco; Soltesz, Ivan; Katona, István

    2014-01-01

    A major challenge in neuroscience is to determine the nanoscale position and quantity of signaling molecules in a cell-type-, and subcellular compartment-specific manner. We therefore developed a novel approach combining cell-specific physiological and anatomical characterization with superresolution imaging, and studied the molecular and structural parameters shaping the physiological properties of synaptic endocannabinoid signaling in the mouse hippocampus. We found that axon terminals of perisomatically-projecting GABAergic interneurons possess increased CB1 receptor number, active-zone complexity, and receptor/effector ratio compared to dendritically-projecting interneurons, in agreement with higher efficiency of cannabinoid signaling at somatic versus dendritic synapses. Furthermore, chronic Δ9-tetrahydrocannabinol administration, which reduces cannabinoid efficacy on GABA release, evoked dramatic CB1-downregulation in a dose-dependent manner. Full receptor recovery required several weeks after cessation of Δ9-tetrahydrocannabinol treatment. These findings demonstrate that cell-type-specific nanoscale analysis of endogenous protein distribution is possible in brain circuits, and identify novel molecular properties controlling endocannabinoid signaling and cannabis-induced cognitive dysfunction. PMID:25485758

  20. Nanoscale mechanical and tribological properties of fluorocarbon films grafted onto plasma-treated low-density polyethylene surfaces

    International Nuclear Information System (INIS)

    Cheng, Q; Komvopoulos, K

    2012-01-01

    Fluorocarbon (FC) films were grafted onto Ar plasma-treated low-density polyethylene (LDPE) surfaces by plasma polymerization and deposition. The evolution of the surface morphology of the grafted FC films was investigated at different scales with an atomic force microscope. Nanoscale sliding experiments performed with a surface force microscope provided insight into the nanotribological properties of Ar plasma-treated LDPE, with and without grafted FC films, in terms of applied normal load and number of sliding cycles. The observed trends are explained in the context of microstructure models accounting for morphological and structure changes at the LDPE surface due to the effects of plasma treatment (e.g., selective etching of amorphous phase, chain crosslinking and FC film grafting) and surface sliding (e.g., crystalline lamellae alignment along the sliding direction). Nanoindentation experiments elucidated the effect of plasma treatment on surface viscoelasticity and global contact stiffness. The results of this study demonstrate that plasma-assisted grafting of FC films is an effective surface modification method for tuning the nanomechanical/tribological properties of polymers. (paper)

  1. Nanoscale surface characterization of aqueous copper corrosion: Effects of immersion interval and orthophosphate concentration

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, Stephanie L. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); United States Environmental Protection Agency, National Risk Management Research Laboratory (NRMRL), Water Supply and Water Resource Division (WSWRD), Cincinnati, OH 45268 (United States); Sprunger, Phillip T. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Center for Advanced Microstructures and Devices, Synchrotron Radiation Facility of Louisiana State University, Baton Rouge, LA 70803 (United States); Kizilkaya, Orhan [Center for Advanced Microstructures and Devices, Synchrotron Radiation Facility of Louisiana State University, Baton Rouge, LA 70803 (United States); Lytle, Darren A. [United States Environmental Protection Agency, National Risk Management Research Laboratory (NRMRL), Water Supply and Water Resource Division (WSWRD), Cincinnati, OH 45268 (United States); Garno, Jayne C., E-mail: jgarno@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2013-11-15

    Morphology changes for copper surfaces exposed to different water parameters were investigated at the nanoscale with atomic force microscopy (AFM), as influenced by changes in pH and the levels of orthophosphate ions. Synthetic water samples were designed to mimic physiological chemistries for drinking water, both with and without addition of orthophosphate over a pH range 6.5–9. Copper surfaces treated with orthophosphate as a corrosion inhibitor after 6 and 24 h were evaluated. Tapping mode AFM images revealed dosing of the water with 6 mg/L of orthophosphate was beneficial in retarding the growth of copper by-products. The chemical composition and oxidation state of the surface deposits were characterized with X-ray diffraction (XRD), near edge X-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared spectroscopy (FTIR).

  2. Determination of morphological features and molecular interactions ...

    African Journals Online (AJOL)

    This research focused on identifying the morphological features and molecular interactions of the Nigerian Bentonitic clays using Scanning Electron Microscope (SEM) characterisation technique. The SEM microstructure images indicated that the bentonite samples are generally moderately dispersive to dispersive with ...

  3. Nanoscale volcanoes: accretion of matter at ion-sculpted nanopores.

    Science.gov (United States)

    Mitsui, Toshiyuki; Stein, Derek; Kim, Young-Rok; Hoogerheide, David; Golovchenko, J A

    2006-01-27

    We demonstrate the formation of nanoscale volcano-like structures induced by ion-beam irradiation of nanoscale pores in freestanding silicon nitride membranes. Accreted matter is delivered to the volcanoes from micrometer distances along the surface. Volcano formation accompanies nanopore shrinking and depends on geometrical factors and the presence of a conducting layer on the membrane's back surface. We argue that surface electric fields play an important role in accounting for the experimental observations.

  4. Phototoxicity and Dosimetry of Nano-scale Titanium Dioxide in Aquatic Organisms

    Science.gov (United States)

    We have been testing nanoscale TiO2 (primarily Evonik P25) in acute exposures to identify and quantify its phototoxicity under solar simulated radiation (SSR), and to develop dose metrics reflective of both nano-scale properties and the photon component of its potency. Several e...

  5. Nanoscale footprints of self-running gallium droplets on GaAs surface.

    Directory of Open Access Journals (Sweden)

    Jiang Wu

    Full Text Available In this work, the nanoscale footprints of self-driven liquid gallium droplet movement on a GaAs (001 surface will be presented and analyzed. The nanoscale footprints of a primary droplet trail and ordered secondary droplets along primary droplet trails are observed on the GaAs surface. A well ordered nanoterrace from the trail is left behind by a running droplet. In addition, collision events between two running droplets are investigated. The exposed fresh surface after a collision demonstrates a superior evaporation property. Based on the observation of droplet evolution at different stages as well as nanoscale footprints, a schematic diagram of droplet evolution is outlined in an attempt to understand the phenomenon of stick-slip droplet motion on the GaAs surface. The present study adds another piece of work to obtain the physical picture of a stick-slip self-driven mechanism in nanoscale, bridging nano and micro systems.

  6. Nanoscale Characterization for the Classroom

    International Nuclear Information System (INIS)

    Carroll, D.L.

    1999-01-01

    This report describes the development of a semester course in 'nano-scale characterization'. The interdisciplinary course is opened to both advanced undergraduate and graduate students with a standard undergraduate preparation in Materials Science, Chemistry, or Physics. The approach is formal rather than the typical 'research seminar' and has a laboratory component

  7. Quantum Transport Simulations of Nanoscale Materials

    KAUST Repository

    Obodo, Tobechukwu Joshua

    2016-01-01

    -performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high

  8. The nanoscale organization of the B lymphocyte membrane☆

    Science.gov (United States)

    Maity, Palash Chandra; Yang, Jianying; Klaesener, Kathrin; Reth, Michael

    2015-01-01

    The fluid mosaic model of Singer and Nicolson correctly predicted that the plasma membrane (PM) forms a lipid bi-layer containing many integral trans-membrane proteins. This model also suggested that most of these proteins were randomly dispersed and freely diffusing moieties. Initially, this view of a dynamic and rather unorganized membrane was supported by early observations of the cell surfaces using the light microscope. However, recent studies on the PM below the diffraction limit of visible light (~ 250 nm) revealed that, at nanoscale dimensions, membranes are highly organized and compartmentalized structures. Lymphocytes are particularly useful to study this nanoscale membrane organization because they grow as single cells and are not permanently engaged in cell:cell contacts within a tissue that can influence membrane organization. In this review, we describe the methods that can be used to better study the protein:protein interaction and nanoscale organization of lymphocyte membrane proteins, with a focus on the B cell antigen receptor (BCR). Furthermore, we discuss the factors that may generate and maintain these membrane structures. PMID:25450974

  9. Morphology and structure of polymers in ultrathin films and constrained geometries

    Science.gov (United States)

    Gullerud, Steven Olaf

    We have explored the organization of polycaprolactone (PCL) constrained in ultrathin films and nanometer-scale domains. Specifically, PCL functionalized with triethoxysilane functional groups was used to create tethered ultrathin films on silicon (100) substrates through silanization, and a sol-gel reaction was used to produce PCL/silsesquioxane composites with nanoscale phase-separated domains. In the first case, analysis by AFM and ellipsometry showed the existence of an amorphous sublayer up to 4 nm thick. Above this, physisorbed PCL formed heterogeneous surface features, up to 7 nm thick, with the morphology dependent on the polymer solution concentration during the deposition process. Low PCL solution concentration produced amorphous globular domains, while higher polymer concentrations allowed the growth of dendritic crystalline features. We report the results of in situ thermal analysis of grafted PCL by AFM, which show the melting of the surface structures at the film surface as well as growth of new dendritic structures upon recrystallization. High tapping forces applied by the AFM tip revealed the presence of crystalline lamellae buried below an amorphous layer in the dendritic structures, as well as in the PCL sublayer when the film was cooled below room temperature. PCL phase separation behavior and morphology in sol-gel organic/inorganic nanocomposites with methylsilsesquioxane (MSSQ) or phenylsilsesquioxane (PSSQ) was probed using TEM, FTIR, and fluorescence spectroscopy of dansyl and pyrene-labeled PCL. Star-like and linear PCL were used to study the effects of molecular weight, endgroup functionality, and polymer geometry on the phase separation behavior in these materials. PCL crystallinity, as detected through FTIR, served to detect the presence of macroscopic phase separation, as well as the critical PCL loading amount at which this occurs, for a given PCL/SSQ system. Fluorescence spectroscopy of dansyl-labeled PCL detected the presence of an

  10. Nanoscale Dewetting Transition in Protein Complex Folding

    Science.gov (United States)

    Hua, Lan; Huang, Xuhui; Liu, Pu; Zhou, Ruhong; Berne, Bruce J.

    2011-01-01

    In a previous study, a surprising drying transition was observed to take place inside the nanoscale hydrophobic channel in the tetramer of the protein melittin. The goal of this paper is to determine if there are other protein complexes capable of displaying a dewetting transition during their final stage of folding. We searched the entire protein data bank (PDB) for all possible candidates, including protein tetramers, dimers, and two-domain proteins, and then performed the molecular dynamics (MD) simulations on the top candidates identified by a simple hydrophobic scoring function based on aligned hydrophobic surface areas. Our large scale MD simulations found several more proteins, including three tetramers, six dimers, and two two-domain proteins, which display a nanoscale dewetting transition in their final stage of folding. Even though the scoring function alone is not sufficient (i.e., a high score is necessary but not sufficient) in identifying the dewetting candidates, it does provide useful insights into the features of complex interfaces needed for dewetting. All top candidates have two features in common: (1) large aligned (matched) hydrophobic areas between two corresponding surfaces, and (2) large connected hydrophobic areas on the same surface. We have also studied the effect on dewetting of different water models and different treatments of the long-range electrostatic interactions (cutoff vs PME), and found the dewetting phenomena is fairly robust. This work presents a few proteins other than melittin tetramer for further experimental studies of the role of dewetting in the end stages of protein folding. PMID:17608515

  11. Fast nanoscale heat-flux modulation with phase-change materials

    OpenAIRE

    Van Zwol , Pieter; Joulain , Karl; Ben-Abdallah , Philippe; Greffet , Jean-Jacques; Chevrier , Joël

    2011-01-01

    International audience; We introduce a new concept for electrically controlled heat flux modulation. A flux contrast larger than 10 dB is expected with switching time on the order of tens of nanoseconds. Heat flux modulation is based on the interplay between radiative heat transfer at the nanoscale and phase change materials. Such large contrasts are not obtainable in solids, or in far field. As such this opens up new horizons for temperature modulation and actuation at the nanoscale.

  12. Enabling complex nanoscale pattern customization using directed self-assembly.

    Science.gov (United States)

    Doerk, Gregory S; Cheng, Joy Y; Singh, Gurpreet; Rettner, Charles T; Pitera, Jed W; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P

    2014-12-16

    Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, 'masking' features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

  13. Thermoelectric efficiency of nanoscale devices in the linear regime

    Science.gov (United States)

    Bevilacqua, G.; Grosso, G.; Menichetti, G.; Pastori Parravicini, G.

    2016-12-01

    We study quantum transport through two-terminal nanoscale devices in contact with two particle reservoirs at different temperatures and chemical potentials. We discuss the general expressions controlling the electric charge current, heat currents, and the efficiency of energy transmutation in steady conditions in the linear regime. With focus in the parameter domain where the electron system acts as a power generator, we elaborate workable expressions for optimal efficiency and thermoelectric parameters of nanoscale devices. The general concepts are set at work in the paradigmatic cases of Lorentzian resonances and antiresonances, and the encompassing Fano transmission function: the treatments are fully analytic, in terms of the trigamma functions and Bernoulli numbers. From the general curves here reported describing transport through the above model transmission functions, useful guidelines for optimal efficiency and thermopower can be inferred for engineering nanoscale devices in energy regions where they show similar transmission functions.

  14. Nanoscale piezoelectric vibration energy harvester design

    Science.gov (United States)

    Foruzande, Hamid Reza; Hajnayeb, Ali; Yaghootian, Amin

    2017-09-01

    Development of new nanoscale devices has increased the demand for new types of small-scale energy resources such as ambient vibrations energy harvesters. Among the vibration energy harvesters, piezoelectric energy harvesters (PEHs) can be easily miniaturized and fabricated in micro and nano scales. This change in the dimensions of a PEH leads to a change in its governing equations of motion, and consequently, the predicted harvested energy comparing to a macroscale PEH. In this research, effects of small scale dimensions on the nonlinear vibration and harvested voltage of a nanoscale PEH is studied. The PEH is modeled as a cantilever piezoelectric bimorph nanobeam with a tip mass, using the Euler-Bernoulli beam theory in conjunction with Hamilton's principle. A harmonic base excitation is applied as a model of the ambient vibrations. The nonlocal elasticity theory is used to consider the size effects in the developed model. The derived equations of motion are discretized using the assumed-modes method and solved using the method of multiple scales. Sensitivity analysis for the effect of different parameters of the system in addition to size effects is conducted. The results show the significance of nonlocal elasticity theory in the prediction of system dynamic nonlinear behavior. It is also observed that neglecting the size effects results in lower estimates of the PEH vibration amplitudes. The results pave the way for designing new nanoscale sensors in addition to PEHs.

  15. Nuclear Magnetic Resonance Study of Nanoscale Ionic Materials

    KAUST Repository

    Oommen, Joanna Mary

    2010-08-13

    Nanoscale ionic materials (NIMs) are a new class of nanomaterials that exhibit interesting properties including negligible vapor pressures and tunable physical states, among others. In this study, we analyzed the temperature-wise performance of NIMs using nuclear magnetic resonance (NMR) spectroscopy. NIMs are relatively stable over a temperature range from 300 to 383 K, rendering them usable in high temperature applications. We confirmed the presence of covalent bonds between the SiO2 core and the sulfonate group and determined relative concentrations of aromatic and aliphatic hydrocarbons. These findings serve as first hand proof-of-concept for the usefulness of NMR analyses in further studies on the diffusive properties of NIMs. © 2010 The Electrochemical Society.

  16. Bulk nanoscale materials in steel products

    International Nuclear Information System (INIS)

    Chehab, B; Wang, X; Masse, J-P; Zurob, H; Embury, D; Bouaziz, O

    2010-01-01

    Although a number of nanoscale metallic materials exhibit interesting mechanical properties the fabrication paths are often complex and difficult to apply to bulk structural materials. However a number of steels which exhibit combinations of plasticity and phase transitions can be deformed to produce ultra high strength levels in the range 1 to 3 GPa. The resultant high stored energy and complex microstructures allow new nanoscale structures to be produced by combinations of recovery and recrystallisation. The resultant structures exhibit totally new combinations of strength and ductility to be achieved. In specific cases this also enables both the nature of the grain boundary structure and the spatial variation in structure to be controlled. In this presentation both the detailed microstructural features and their relation to the strength, work-hardening capacity and ductility will be discussed for a number of martensitic and austenitic steels.

  17. Potential of silicon nanowires structures as nanoscale piezoresistors in mechanical sensors

    International Nuclear Information System (INIS)

    Messina, M; Njuguna, J

    2012-01-01

    This paper presents the design of a single square millimeter 3-axial accelerometer for bio-mechanics measurements that exploit the potential of silicon nanowires structures as nanoscale piezoresistors. The main requirements of this application are miniaturization and high measurement accuracy. Nanowires as nanoscale piezoresistive devices have been chosen as sensing element, due to their high sensitivity and miniaturization achievable. By exploiting the electro-mechanical features of nanowires as nanoscale piezoresistors, the nominal sensor sensitivity is overall boosted by more than 30 times. This approach allows significant higher accuracy and resolution with smaller sensing element in comparison with conventional devices without the need of signal amplification.

  18. Determination of morphology and properties of carbon nanofibers and carbon nanofiber polymer nanocomposites

    Science.gov (United States)

    Lawrence, Joseph G.

    Vapor grown carbon nanofibers which resemble carbon nanotubes in structure and properties, have been extensively manufactured and investigated in recent years. Carbon nanofibers have been used for producing multifunctional materials due to their excellent properties and low cost of production. Since, commercially available vapor grown carbon nanofibers are subjected to different processing and post processing conditions, the morphology and properties of these nanofibers are not well-known. In this study, we focus on the characterization of the morphology and properties of these nanofibers and the polymer nanocomposites made using these nanofibers as reinforcements. The morphology of the nanofibers was studied employing high resolution Transmission Electron Microscopy (TEM) images. The analysis showed that the nanofibers consist primarily of conical nanofibers, but can contain a significant amount of bamboo nanofibers. Most of the conical nanofibers were found to consist of an ordered inner layer and a disordered outer layer, with the cone angle distribution of the inner layers indicating that these cannot have a stacked cone structure but are compatible with a cone-helix structure. Nanofibers that were heat treated to temperatures above 1,500°C undergo a structural transformation with the ordered inner layers changing from a cone-helix structure to a highly ordered multiwall stacked cone structure. Due to the complexity in the structure of these nanofibers, a novel method to study the elastic properties and corresponding morphology of individual nanofibers has been developed combining Atomic Force Microscopy (AFM), TEM and Focused Ion Beam (FIB) technology. Employing the developed method, the elastic modulus of individual nanofibers and their corresponding dimensions and morphology were determined. The dependence of elastic properties on the wall thickness and the orientation of graphene sheets in the nanofibers were studied. The elastic modulus of these

  19. Nano-scale islands of ruthenium oxide as an electrochemical sensor for iodate and periodate determination

    International Nuclear Information System (INIS)

    Chatraei, Fatemeh; Zare, Hamid R.

    2013-01-01

    In this study, a promising electrochemical sensor was fabricated by the electrodeposition of nano-scale islands of ruthenium oxide (ruthenium oxide nanoparticles, RuON) on a glassy carbon electrode (RuON–GCE). Then, the electrocatalytic oxidation of iodate and periodate was investigated on it, using cyclic voltammetry, chronoamperometry and amperometry as diagnostic techniques. The charge transfer coefficient, α, and the charge transfer rate constant, k s , for electron transfer between RuON and GCE were calculated as 0.5 ± 0.03 and 9.0 ± 0.7 s −1 respectively. A comparison of the data obtained from the electrocatalytic reduction of iodate and periodate at a bare GCE (BGCE) and RuON–GCE clearly shows that the unique electronic properties of nanoparticles definitely improve the characteristics of iodate and periodate electrocatalytic reduction. The kinetic parameters such as the electron transfer coefficient, α, and the heterogeneous electron transfer rate constant, k′, for the reduction of iodate and periodate at RuON–GCE surface were determined using cyclic voltammetry. Amperometry revealed a good linear relationship between the peak current and the concentration of iodate and periodate. The detection limits of 0.9 and 0.2 μM were calculated for iodate and periodate respectively. Highlights: ► Ruthenium oxide nanoparticles, RuON, were used for electrocatalytic reduction iodate and periodate. ► Formal potential, E 0 ′, of the surface redox couple of RuON is pH-dependent. ► The heterogeneous electron transfer rate constant values between both analytes and RuON were calculated.

  20. Quantitative analysis of nanoscale intranuclear structural alterations in hippocampal cells in chronic alcoholism via transmission electron microscopy imaging.

    Science.gov (United States)

    Sahay, Peeyush; Shukla, Pradeep K; Ghimire, Hemendra M; Almabadi, Huda M; Tripathi, Vibha; Mohanty, Samarendra K; Rao, Radhakrishna; Pradhan, Prabhakar

    2017-03-01

    Chronic alcoholism is known to alter the morphology of the hippocampus, an important region of cognitive function in the brain. Therefore, to understand the effect of chronic alcoholism on hippocampal neural cells, we employed a mouse model of chronic alcoholism and quantified intranuclear nanoscale structural alterations in these cells. Transmission electron microscopy (TEM) images of hippocampal neurons were obtained, and the degree of structural alteration in terms of mass density fluctuation was determined using the light-localization properties of optical media generated from TEM imaging. The results, which were obtained at length scales ranging from ~30 to 200 nm, show that 10-12 week-old mice fed a Lieber-DeCarli liquid (alcoholic) diet had a higher degree of structural alteration than control mice fed a normal diet without alcohol. The degree of structural alteration became significantly distinguishable at a sample length of ~100 nm, which is the typical length scale of the building blocks of cells, such as DNA, RNA, proteins and lipids. Interestingly, different degrees of structural alteration at such length scales suggest possible structural rearrangement of chromatin inside the nuclei in chronic alcoholism.

  1. The Relationship between Morphological Awareness and Morphological Decomposition among English Language Learners

    Science.gov (United States)

    Kraut, Rachel

    2015-01-01

    Morphological awareness facilitates many reading processes. For this reason, L1 and L2 learners of English are often directly taught to use their knowledge of English morphology as a useful reading strategy for determining parts of speech and meaning of novel words. Over time, use of morphological awareness skills while reading develops into an…

  2. Humidity effects on the electronic transport properties in carbon based nanoscale device

    International Nuclear Information System (INIS)

    He, Jun; Chen, Ke-Qiu

    2012-01-01

    By applying nonequilibrium Green's functions in combination with the density functional theory, we investigate the effect of humidity on the electronic transport properties in carbon based nanoscale device. The results show that different humidity may form varied localized potential barrier, which is a very important factor to affect the stability of electronic transport in the nanoscale system. A mechanism for the humidity effect is suggested. -- Highlights: ► Electronic transport in carbon based nanoscale device. ► Humidity affects the stability of electronic transport. ► Different humidity may form varied localized potential barrier.

  3. Inelastic transport theory for nanoscale systems

    DEFF Research Database (Denmark)

    Frederiksen, Thomas

    2007-01-01

    This thesis describes theoretical and numerical investigations of inelastic scat- tering and energy dissipation in electron transport through nanoscale sys- tems. A computational scheme, based on a combination of density functional theory (DFT) and nonequilibrium Green’s functions (NEGF), has been...

  4. Flexible nanoscale high-performance FinFETs

    KAUST Repository

    Sevilla, Galo T.; Ghoneim, Mohamed T.; Fahad, Hossain M.; Rojas, Jhonathan Prieto; Hussain, Aftab M.; Hussain, Muhammad Mustafa

    2014-01-01

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show

  5. Is there an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors? Part II

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huajie, E-mail: wanghuajie972001@163.com; Sun Yuanyuan; Cao Ying, E-mail: caoying1130@sina.com; Wang Kui; Yang Lin [Henan Normal University, College of Chemistry and Environmental Science (China); Zhang Yidong; Zheng Zhi [Xuchang University, Institute of Surface Micro and Nano Materials (China)

    2012-05-15

    Although nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured surfaces, whether there is an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors is still controversial. In this study, porous aluminum oxide membranes with different pore sizes ranging from 25 to 120 nm were prepared by the anodic oxidation technique. The surface morphology, topography and wettability were analyzed by scanning electron microscope, atomic force microscope and water contact angle measurement, respectively. The results indicated that the synergistic action of the nano-topography structure and hydrophilic/hydrophobic properties resulted in a highest protein adsorption on the aluminum oxide membrane with 80 nm pore size. Additionally, the morphological, metabolic and cell counting methods showed that cells had different sensitivity to porous aluminum oxide membranes with different surface features. Furthermore, this sensitivity was cell type dependent. The optimal pore size of aluminum oxide membranes for cell growth was 80 nm for PC12 cells and 50 nm for NIH 3T3 cells.

  6. MD Simulation on Collision Behavior Between Nano-Scale TiO₂ Particles During Vacuum Cold Spraying.

    Science.gov (United States)

    Yao, Hai-Long; Yang, Guan-Jun; Li, Chang-Jiu

    2018-04-01

    Particle collision behavior influences significantly inter-nano particle bonding formation during the nano-ceramic coating deposition by vacuum cold spraying (or aerosol deposition method). In order to illuminate the collision behavior between nano-scale ceramic particles, molecular dynamic simulation was applied to explore impact process between nano-scale TiO2 particles through controlling impact velocities. Results show that the recoil efficiency of the nano-scale TiO2 particle is decreased with the increase of the impact velocity. Nano-scale TiO2 particle exhibits localized plastic deformation during collision at low velocities, while it is intensively deformed by collision at high velocities. This intensive deformation promotes the nano-particle adhesion rather than rebounding off. A relationship between the adhesion energy and the rebound energy is established for the bonding formation of the nano-scale TiO2 particle. The adhesion energy required to the bonding formation between nano-scale ceramic particles can be produced by high velocity collision.

  7. Design exploration of emerging nano-scale non-volatile memory

    CERN Document Server

    Yu, Hao

    2014-01-01

    This book presents the latest techniques for characterization, modeling and design for nano-scale non-volatile memory (NVM) devices.  Coverage focuses on fundamental NVM device fabrication and characterization, internal state identification of memristic dynamics with physics modeling, NVM circuit design, and hybrid NVM memory system design-space optimization. The authors discuss design methodologies for nano-scale NVM devices from a circuits/systems perspective, including the general foundations for the fundamental memristic dynamics in NVM devices.  Coverage includes physical modeling, as well as the development of a platform to explore novel hybrid CMOS and NVM circuit and system design.   • Offers readers a systematic and comprehensive treatment of emerging nano-scale non-volatile memory (NVM) devices; • Focuses on the internal state of NVM memristic dynamics, novel NVM readout and memory cell circuit design, and hybrid NVM memory system optimization; • Provides both theoretical analysis and pr...

  8. Effects of nanoscale contacts to graphene

    NARCIS (Netherlands)

    Franklin, A.D.; Han, S.-J.; Bol, A.A.; Haensch, W.

    2011-01-01

    Understanding and optimizing transport between metal contacts and graphene is one of the foremost challenges for graphene devices. In this letter, we present the first results on the effects of reducing contact dimensions to the nanoscale in single-layer graphene transistors. Using noninvasive

  9. Nanoscale Nutrient Delivery Systems for Food Applications: Improving Bioactive Dispersibility, Stability, and Bioavailability.

    Science.gov (United States)

    McClements, David Julian

    2015-07-01

    There has been a surge of interest in the development of nanoscale systems for the encapsulation, protection, and delivery of lipophilic nutrients, vitamins, and nutraceuticals. This review article highlights the challenges associated with incorporating these lipophilic bioactive components into foods, and then discusses potential nanoscale delivery systems that can be used to overcome these challenges. In particular, the desirable characteristics required for any nanoscale delivery system are presented, as well as methods of fabricating them and of characterizing them. An overview of different delivery systems is given, such as microemulsions, nanoemulsions, emulsions, microgels, and biopolymer nanoparticles, and their potential applications are discussed. Nanoscale delivery systems have considerable potential within the food industry, but they must be carefully formulated to ensure that they are safe, economically viable, and effective. Nanoscale delivery systems have numerous potential applications in the food industry for encapsulating, protecting, and releasing bioactive agents, such as nutraceuticals and vitamins. This review article highlights methods for designing, fabricating, characterizing, and utilizing edible nanoparticles from a variety of different food-grade ingredients. © 2015 Institute of Food Technologists®

  10. Cell-specific STORM super-resolution imaging reveals nanoscale organization of cannabinoid signaling.

    Science.gov (United States)

    Dudok, Barna; Barna, László; Ledri, Marco; Szabó, Szilárd I; Szabadits, Eszter; Pintér, Balázs; Woodhams, Stephen G; Henstridge, Christopher M; Balla, Gyula Y; Nyilas, Rita; Varga, Csaba; Lee, Sang-Hun; Matolcsi, Máté; Cervenak, Judit; Kacskovics, Imre; Watanabe, Masahiko; Sagheddu, Claudia; Melis, Miriam; Pistis, Marco; Soltesz, Ivan; Katona, István

    2015-01-01

    A major challenge in neuroscience is to determine the nanoscale position and quantity of signaling molecules in a cell type- and subcellular compartment-specific manner. We developed a new approach to this problem by combining cell-specific physiological and anatomical characterization with super-resolution imaging and studied the molecular and structural parameters shaping the physiological properties of synaptic endocannabinoid signaling in the mouse hippocampus. We found that axon terminals of perisomatically projecting GABAergic interneurons possessed increased CB1 receptor number, active-zone complexity and receptor/effector ratio compared with dendritically projecting interneurons, consistent with higher efficiency of cannabinoid signaling at somatic versus dendritic synapses. Furthermore, chronic Δ(9)-tetrahydrocannabinol administration, which reduces cannabinoid efficacy on GABA release, evoked marked CB1 downregulation in a dose-dependent manner. Full receptor recovery required several weeks after the cessation of Δ(9)-tetrahydrocannabinol treatment. These findings indicate that cell type-specific nanoscale analysis of endogenous protein distribution is possible in brain circuits and identify previously unknown molecular properties controlling endocannabinoid signaling and cannabis-induced cognitive dysfunction.

  11. Nanoscale Organic Hybrid Electrolytes

    KAUST Repository

    Nugent, Jennifer L.

    2010-08-20

    Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Nanoscale Organic Hybrid Electrolytes

    KAUST Repository

    Nugent, Jennifer L.; Moganty, Surya S.; Archer, Lynden A.

    2010-01-01

    Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Nanoscale science and nanotechnology education in Africa ...

    African Journals Online (AJOL)

    Nanoscale science and nanotechnology education in Africa: importance and ... field with its footing in chemistry, physics, molecular biology and engineering. ... career/business/development opportunities, risks and policy challenges that would ...

  14. Nanoscale Structural/Chemical Characterization of Manganese Oxide Surface Layers and Nanoparticles, and the Associated Implications for Drinking Water

    Science.gov (United States)

    Michel Eduardo Vargas Vallejo

    Water treatment facilities commonly reduce soluble contaminants, such as soluble manganese (Mn2+), in water by oxidation and subsequent filtration. Previous studies have shown that conventional porous filter system removes Mn2+ from drinking water by developing Mn-oxides (MnO x(s)) bearing coating layers on the surface of filter media. Multiple models have been developed to explain this Mn2+ removal process and the formation mechanism of MnOx(s) coatings. Both, experimental and theoretical studies to date have been largely focused on the micrometer to millimeter scale range; whereas, coating layers are composed of nanoscale particles and films. Hence, understanding the nanoscale particle and film formation mechanisms is essential to comprehend the complexity of soluble contaminant removal processes. The primary objective of this study was to understand the initial MnOx(s) coating formation mechanisms and evaluate the influence of filter media characteristics on these processes. We pursued this objective by characterizing at the micro and nanoscale MnO x(s) coatings developed on different filter media by bench-scale column tests with simulating inorganic aqueous chemistry of a typical coagulation fresh water treatment plant, where free chlorine is present across filter bed. Analytical SEM and TEM, powder and synchrotron-based XRD, XPS, and ICPMS were used for characterization of coatings, filter media and water solution elemental chemistry. A secondary objective was to model how surface coating formation occurred and its correlation with experimentally observed physical characteristics. This modeling exercise indicates that surface roughness and morphology of filtering media are the major contributing factors in surface coating formation process. Contrary to previous models that assumed a uniform distribution and growth of surface coating, the experimental results showed that greater amounts of coating were developed in rougher areas. At the very early stage of

  15. A new method to produce nanoscale iron for nitrate removal

    International Nuclear Information System (INIS)

    Chen, S.-S.; Hsu, H.-D.; Li, C.-W.

    2004-01-01

    This article proposes a novel technology combining electrochemical and ultrasonic methods to produce nanoscale zero valent iron (NZVI). With platinum placed in the cathode and the presence of the dispersion agent, 0.2g/l cetylpyridinium chloride (CPC), a cation surfactant, in the solution, the nanoscale iron particle was successfully produced with diameter of 1-20 nm and specific surface area of 25.4m 2 /g. The produced NZVI was tested in batch experiments for nitrate removal. The results showed that the nitrate reduction was affected by pH. Al low pH, nitrate was shown faster decline and more reduction in term of g NO 3 - -N/g NZVI. The reaction was first order and kinetic coefficients for the four pHs were directly related to pH with R 2 >0.95. Comparing with microscale zero-valent iron (45μm, 0.183m 2 /g), microscale zero-valent iron converted nitrate to ammonia completely, but NZVI converted nitrate to ammonia partially from 36.2 to 45.3% dependent on pH. For mass balance of iron species, since the dissolved iron in the solution was very low ( 2 O 3 was recognized. Thus the reaction mechanisms can be determined

  16. Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

    Science.gov (United States)

    Sekkal, W.; Zaoui, A.

    2013-04-01

    Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images.

  17. One-pot synthesis of multifunctional nanoscale metal-organic frameworks as an effective antibacterial agent against multidrug-resistant Staphylococcus aureus

    Science.gov (United States)

    Chowdhuri, Angshuman Ray; Das, Balaram; Kumar, Amit; Tripathy, Satyajit; Roy, Somenath; Sahu, Sumanta Kumar

    2017-03-01

    Drug-resistant bacteria are an increasingly serious threat to global public health. In particular, infections from multidrug-resistant (MDR) Gram-positive bacteria (i.e. Staphylococcus aureus) are growing global health concerns. In this work, we report the first use of nanoscale metal-organic frameworks (NMOFs) coencapsulating an antibiotic (vancomycin) and targeting ligand (folic acid) in one pot to enhance therapeutic efficacy against MDR S. aureus. Zeolitic imidazolate framework (ZIF-8) NMOFs, which have globular morphologies coencapsulating vancomycin and folic acid, are characterized by transmission electron microscopy, field-emission scanning electron microscopy, powder x-ray diffraction, ulltraviolet-visible spectroscopy, and dynamic light-scattering techniques. We determined that the presence of folic acid on the surface of the NMOFs is significant in the sense of effective uptake by MDR S. aureus through endocytosis. The functionalized NMOFs transport vancomycin across the cell wall of MDR S. aureus and enhance antibacterial activity, which has been confirmed from studies of the minimum inhibitory concentration, minimum bactericidal concentration, cytotoxicity of bacterial cells, and generation of reactive oxygen species. This work shows that functionalized NMOFs hold great promise for effective treatment of MDR S. aureus.

  18. Preparation of nano-hydroxyapatite particles with different morphology and their response to highly malignant melanoma cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Li Bo [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China); Guo Bo [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China); West China Eye Center of Huaxi Hospital, Sichuan University, Chengdu 610064 (China); Fan Hongsong [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China)], E-mail: leewave@126.com; Zhang Xingdong [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China)

    2008-11-15

    To investigate the effects of nano-hydroxyapatite (HA) particles with different morphology on highly malignant melanoma cells, three kinds of HA particles with different morphology were synthesized and co-cultured with highly malignant melanoma cells using phosphate-buffered saline (PBS) as control. A precipitation method with or without citric acid addition as surfactant was used to produce rod-like hydroxyapatite (HA) particles with nano- and micron size, respectively, and a novel oil-in-water emulsion method was employed to prepare ellipse-like nano-HA particles. Particle morphology and size distribution of the as prepared HA powders were characterized by transmission electron microscope (TEM) and dynamic light scattering technique. The nano- and micron HA particles with different morphology were co-cultured with highly malignant melanoma cells. Immunofluorescence analysis and MTT assay were employed to evaluate morphological change of nucleolus and proliferation of tumour cells, respectively. To compare the effects of HA particles on cell response, the PBS without HA particles was used as control. The experiment results indicated that particle nanoscale effect rather than particle morphology of HA was more effective for the inhibition on highly malignant melanoma cells proliferation.

  19. Multiple simultaneous fabrication of molecular nanowires using nanoscale electrocrystallization

    International Nuclear Information System (INIS)

    Hasegawa, Hiroyuki; Ueda, Rieko; Kubota, Tohru; Mashiko, Shinro

    2006-01-01

    We carried out a multiple simultaneous fabrication based on the nanoscale electrocrystallization to simultaneously construct molecular nanowires at two or more positions. This substrate-independent nanoscale electrocrystallization process enables nanowires fabrication at specific positions using AC. We also succeeded in multiple fabrications only at each gap between the electrode tips. We found that π-stack was formed along the long axis of the nanowires obtained by analyzing the selected-area electron diffraction. We believe this technique has the potential for expansion to the novel low-cost and energy-saving fabrication of high-performance nanodevices

  20. A nanoscale ordered materials diffractometer for the SNS

    International Nuclear Information System (INIS)

    Neuefeind, Joerg; Chipley, Kenneth K.; Tulk, Chris A.; Simonson, J. Michael; Winokur, Michael J.

    2006-01-01

    The Nanoscale Ordered Materials Diffractometer (NOMAD) is one of five neutron scattering instruments being managed within the Spallation Neutron Source (SNS) Instruments-Next Generation (SING) project. NOMAD is designed as a high-flux, medium-resolution diffractometer using a large bandwidth of neutron energies and extensive detector coverage to perform structural determinations of local order in crystalline and amorphous materials. The instrument will enable studies of a large variety of samples ranging from liquids, solutions, glasses, polymers, and nanocrystalline materials to long-range ordered crystals and will allow unprecedented access to high-resolution pair distribution functions, small-contrast isotope substitution experiments, small sample sizes, and parametric studies. Project completion for the instrument is anticipated in 2010 and a review of the design status will be given

  1. Nanoscale thermal transport. II. 2003–2012

    International Nuclear Information System (INIS)

    Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

    2014-01-01

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and

  2. Benchtop Nanoscale Patterning Using Soft Lithography

    Science.gov (United States)

    Meenakshi, Viswanathan; Babayan, Yelizaveta; Odom, Teri W.

    2007-01-01

    This paper outlines several benchtop nanoscale patterning experiments that can be incorporated into undergraduate laboratories or advanced high school chemistry curricula. The experiments, supplemented by an online video lab manual, are based on soft lithographic techniques such as replica molding, micro-molding in capillaries, and micro-contact…

  3. Programmed assembly of nanoscale structures using peptoids.

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jianhua (University of the Pacific, Stockton, CA); Russell, Scott (California State University, Stanislaus, Turlock, CA); Morishetti, Kiran (University of the Pacific, Stockton, CA); Robinson, David B.; Zuckermann, Ronald N. (Lawrence Berkeley National Laboratory, Berkeley, CA); Buffleben, George M.; Hjelm, Rex P. (Los Alamos National Laboratory, Los Alamos, NM); Kent, Michael Stuart (Sandia National Laboratories, Albuquerque, NM)

    2011-02-01

    Sequence-specific polymers are the basis of the most promising approaches to bottom-up programmed assembly of nanoscale materials. Examples include artificial peptides and nucleic acids. Another class is oligo(N-functional glycine)s, also known as peptoids, which permit greater sidegroup diversity and conformational control, and can be easier to synthesize and purify. We have developed a set of peptoids that can be used to make inorganic nanoparticles more compatible with biological sequence-specific polymers so that they can be incorporated into nucleic acid or other biologically based nanostructures. Peptoids offer degrees of modularity, versatility, and predictability that equal or exceed other sequence-specific polymers, allowing for rational design of oligomers for a specific purpose. This degree of control will be essential to the development of arbitrarily designed nanoscale structures.

  4. 78 FR 24241 - Nanoscale Science, Engineering, and Technology Subcommittee; Committee on Technology, National...

    Science.gov (United States)

    2013-04-24

    ... OFFICE OF SCIENCE AND TECHNOLOGY POLICY Nanoscale Science, Engineering, and Technology.... SUMMARY: The National Nanotechnology Coordination Office (NNCO), on behalf of the Nanoscale Science, Engineering, and Technology (NSET) Subcommittee of the Committee on Technology, National Science and...

  5. 77 FR 61448 - Nanoscale Science, Engineering and Technology Subcommittee Committee on Technology, National...

    Science.gov (United States)

    2012-10-09

    ... OFFICE OF SCIENCE AND TECHNOLOGY POLICY Nanoscale Science, Engineering and Technology Subcommittee...: The National Nanotechnology Coordination Office (NNCO), on behalf of the Nanoscale Science, Engineering, and Technology (NSET) Subcommittee of the Committee on Technology, National Science and...

  6. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  7. Molecular dynamics investigation of nanoscale substrate topography and its interaction with liquids

    Science.gov (United States)

    Cordeiro Rodrigues, Jhonatam

    Nanotechnology has been presenting successful applications in several areas. However, experimentation with nanoscale materials is costly and limited in analysis capability. This research investigates the use of molecular dynamics (MD) simulations to model and study nanomaterials and manufacturing processes. MD simulations are employed to reduce cost, optimize design, increase productivity and allow for the investigation of material interactions not yet observable through experimentation. This work investigates the interaction of water with substrates at the nanoscale. The effect of temperature, droplet impingement velocities and size, as well as substrate material, are investigated at the nanoscale. Several substrate topography designs were modeled to reveal their influence on the wettability of the substrate. Nanoscale gold and silicon substrates are more hydrophilic at higher temperatures than at room temperature. The reduction in droplet diameter increases its wettability. High impingement velocity of droplets does not influence final wettability of substrates but induces higher diffusion rates of droplets in a heated environment. Droplets deposited over a gradient of surface exposure presents spontaneous movement. The Leidenfrost effect was investigated at the nanoscale. Droplets of 4 and 10nm in diameter presented behaviors pertinent to the Leidenfrost effect at 373K, significantly lower than at micro scale and of potential impact to the field. Topographical features were manipulated using superhydrophobic coating resulting in micro whiskers. Nanoimprint lithography (NIL) was used to manufacture substrate topographies at the nanoscale. Water droplets were deposited on the substrates and their wettability was measured using droplet contact angles. Lower surface area exposure resulted in higher contact angles. The experimental relationships between surface topography and substrate wettability were used to validate the insights gained from MD simulations for

  8. Geometrical tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Kristensen, Anders; Xiao, Sanshui

    2010-01-01

    We investigate the capacitance tuning of nanoscale split-ring resonators. An LC-model predicts a simple dependence of resonance frequency on slit aspect ratio. Experimental and numerical data follow the predictions of the LC-model....

  9. 77 FR 56681 - Nanoscale Science, Engineering, and Technology Subcommittee; Committee on Technology, National...

    Science.gov (United States)

    2012-09-13

    ... OFFICE OF SCIENCE AND TECHNOLOGY POLICY Nanoscale Science, Engineering, and Technology...: Notice of webinar. SUMMARY: The National Nanotechnology Coordination Office (NNCO), on behalf of the Nanoscale Science, Engineering, and Technology (NSET) Subcommittee of the Committee on Technology, National...

  10. Single molecules and single nanoparticles as windows to the nanoscale

    Science.gov (United States)

    Caldarola, Martín; Orrit, Michel

    2018-05-01

    Since the first optical detection of single molecules, they have been used as nanometersized optical sensors to explore the physical properties of materials and light-matter interaction at the nanoscale. Understanding nanoscale properties of materials is fundamental for the development of new technology that requires precise control of atoms and molecules when the quantum nature of matter cannot be ignored. In the following lines, we illustrate this journey into nanoscience with some experiments from our group.

  11. Effects of particle composition and environmental parameters on catalytic hydrodechlorination of trichloroethylene by nanoscale bimetallic Ni-Fe.

    Science.gov (United States)

    Wei, Jianjun; Qian, Yajing; Liu, Wenjuan; Wang, Lutao; Ge, Yijie; Zhang, Jianghao; Yu, Jiang; Ma, Xingmao

    2014-05-01

    Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene (TCE), one of the most commonly detected chlorinated organic compounds in groundwater. Ethane was the predominant product. The greatest dechlorination efficiency was achieved at 22 molar percent of nickel. This nanoscale Ni-Fe is poorly ordered and inhomogeneous; iron dissolution occurred whereas nickel was relatively stable during the 24-hr reaction. The morphological characterization provided significant new insights on the mechanism of catalytic hydrodechlorination by bimetallic nanoparticles. TCE degradation and ethane production rates were greatly affected by environmental parameters such as solution pH, temperature and common groundwater ions. Both rate constants decreased and then increased over the pH range of 6.5 to 8.0, with the minimum value occurring at pH 7.5. TCE degradation rate constant showed an increasing trend over the temperature range of 10 to 25°C. However, ethane production rate constant increased and then decreased over the range, with the maximum value occurring at 20°C. Most salts in the solution appeared to enhance the reaction in the first half hour but overall they displayed an inhibitory effect. Combined ions showed a similar effect as individual salts. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  12. Sex determination of Pohnpei Micronesian kingfishers using morphological and molecular genetic techniques

    Science.gov (United States)

    Kesler, Dylan C.; Lopes, I.F.; Haig, Susan M.

    2006-01-01

    Conservation-oriented studies of Micronesian Kingfishers (Todiramphus cinnamominus) have been hindered by a lack of basic natural history information, despite the status of the Guam subspecies (T. c. cinnamominus) as one of the most endangered species in the world. We used tissue samples and morphometric measures from museum specimens and wild-captured Pohnpei Micronesian Kingfishers (T. c. reichenbachii) to develop methods for sex determination. We present a modified molecular protocol and a discriminant function that yields the probability that a particular individual is male or female. Our results revealed that females were significantly larger than males, and the discriminant function correctly predicted sex in 73% (30/41) of the individuals. The sex of 86% (18/21) of individuals was correctly assigned when a moderate reliability threshold was set. Sex determination using molecular genetic techniques was more reliable than methods based on morphology. Our results will facilitate recovery efforts for the critically endangered Guam Micronesian Kingfisher and provide a basis for sex determination in the 11 other endangered congeners in the Pacific Basin.

  13. Fabrication of ordered arrays of micro- and nanoscale features with control over their shape and size via templated solid-state dewetting.

    Science.gov (United States)

    Ye, Jongpil

    2015-05-08

    Templated solid-state dewetting of single-crystal films has been shown to be used to produce regular patterns of various shapes. However, the materials for which this patterning method is applicable, and the size range of the patterns produced are still limited. Here, it is shown that ordered arrays of micro- and nanoscale features can be produced with control over their shape and size via solid-state dewetting of patches patterned from single-crystal palladium and nickel films of different thicknesses and orientations. The shape and size characteristics of the patterns are found to be widely controllable with varying the shape, width, thickness, and orientation of the initial patches. The morphological evolution of the patches is also dependent on the film material, with different dewetting behaviors observed in palladium and nickel films. The mechanisms underlying the pattern formation are explained in terms of the influence on Rayleigh-like instability of the patch geometry and the surface energy anisotropy of the film material. This mechanistic understanding of pattern formation can be used to design patches for the precise fabrication of micro- and nanoscale structures with the desired shapes and feature sizes.

  14. The growth of nanoscale ZnO films by pulsed-spray evaporation chemical vapor deposition and their structural, electric and optical properties

    International Nuclear Information System (INIS)

    Jiang Yinzhu; Bahlawane, Naoufal

    2010-01-01

    Great interest in nanoscale thin films (sub-100 nm) has been stimulated by the developing demands of functional devices. In this paper, nanoscale zinc oxide (ZnO) thin films were deposited on glass substrates at 300 o C by pulsed-spray evaporation chemical vapor deposition. Scanning electron micrographs indicate uniform surface morphologies composed of nanometer-sized spherical particles. The growth kinetics and growth mode are studied and the relationship between the film thickness and the electric properties with respect to the growth mode is interpreted. X-ray diffraction shows that all ZnO films grown by this process were crystallized in a hexagonal structure and highly oriented with their c-axes perpendicular to the plane of the substrate. Optical measurements show transparencies above 85% in the visible spectral range for all films. The absorbance in the UV spectral range respects well the Beer-Lambert law, enabling an accurate optical thickness measurement, and the absorption coefficient was measured for a selected wavelength. The measured band gap energies exhibit an almost constant value of 3.41 eV for all films with different thicknesses, which attributed to the thickness-independent crystallite size.

  15. Brillouin gain enhancement in nano-scale photonic waveguide

    Science.gov (United States)

    Nouri Jouybari, Soodabeh

    2018-05-01

    The enhancement of stimulated Brillouin scattering in nano-scale waveguides has a great contribution in the improvement of the photonic devices technology. The key factors in Brillouin gain are the electrostriction force and radiation pressure generated by optical waves in the waveguide. In this article, we have proposed a new scheme of nano-scale waveguide in which the Brillouin gain is considerably improved compared to the previously-reported schemes. The role of radiation pressure in the Brillouin gain was much higher than the role of the electrostriction force. The Brillouin gain strongly depends on the structural parameters of the waveguide and the maximum value of 12127 W-1 m-1 is obtained for the Brillouin gain.

  16. Nanoscale roughness contact in a slider-disk interface.

    Science.gov (United States)

    Hua, Wei; Liu, Bo; Yu, Shengkai; Zhou, Weidong

    2009-07-15

    The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed.

  17. Nanoscale roughness contact in a slider-disk interface

    International Nuclear Information System (INIS)

    Hua Wei; Liu Bo; Yu Shengkai; Zhou Weidong

    2009-01-01

    The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed.

  18. Nanoscale defect architectures and their influence on material properties

    Science.gov (United States)

    Campbell, Branton

    2006-10-01

    Diffraction studies of long-range order often permit one to unambiguously determine the atomic structure of a crystalline material. Many interesting material properties, however, are dominated by nanoscale crystal defects that can't be characterized in this way. Fortunately, advances in x-ray detector technology, synchrotron x-ray source brightness, and computational power make it possible to apply new methods to old problems. Our research group uses multi-megapixel x-ray cameras to map out large contiguous volumes of reciprocal space, which can then be visually explored using graphics engines originally developed by the video-game industry. Here, I will highlight a few recent examples that include high-temperature superconductors, colossal magnetoresistors and piezoelectric materials.

  19. Cationic nanoparticles induce nanoscale disruption in living cell plasma membranes.

    Science.gov (United States)

    Chen, Jiumei; Hessler, Jessica A; Putchakayala, Krishna; Panama, Brian K; Khan, Damian P; Hong, Seungpyo; Mullen, Douglas G; Dimaggio, Stassi C; Som, Abhigyan; Tew, Gregory N; Lopatin, Anatoli N; Baker, James R; Holl, Mark M Banaszak; Orr, Bradford G

    2009-08-13

    It has long been recognized that cationic nanoparticles induce cell membrane permeability. Recently, it has been found that cationic nanoparticles induce the formation and/or growth of nanoscale holes in supported lipid bilayers. In this paper, we show that noncytotoxic concentrations of cationic nanoparticles induce 30-2000 pA currents in 293A (human embryonic kidney) and KB (human epidermoid carcinoma) cells, consistent with a nanoscale defect such as a single hole or group of holes in the cell membrane ranging from 1 to 350 nm(2) in total area. Other forms of nanoscale defects, including the nanoparticle porating agents adsorbing onto or intercalating into the lipid bilayer, are also consistent; although the size of the defect must increase to account for any reduction in ion conduction, as compared to a water channel. An individual defect forming event takes 1-100 ms, while membrane resealing may occur over tens of seconds. Patch-clamp data provide direct evidence for the formation of nanoscale defects in living cell membranes. The cationic polymer data are compared and contrasted with patch-clamp data obtained for an amphiphilic phenylene ethynylene antimicrobial oligomer (AMO-3), a small molecule that is proposed to make well-defined 3.4 nm holes in lipid bilayers. Here, we observe data that are consistent with AMO-3 making approximately 3 nm holes in living cell membranes.

  20. Nanoscale Correlated Disorder in Out-of-Equilibrium Myelin Ultrastructure.

    Science.gov (United States)

    Campi, Gaetano; Di Gioacchino, Michael; Poccia, Nicola; Ricci, Alessandro; Burghammer, Manfred; Ciasca, Gabriele; Bianconi, Antonio

    2018-01-23

    Ultrastructural fluctuations at nanoscale are fundamental to assess properties and functionalities of advanced out-of-equilibrium materials. We have taken myelin as a model of supramolecular assembly in out-of-equilibrium living matter. Myelin sheath is a simple stable multilamellar structure of high relevance and impact in biomedicine. Although it is known that myelin has a quasi-crystalline ultrastructure, there is no information on its fluctuations at nanoscale in different states due to limitations of the available standard techniques. To overcome these limitations, we have used scanning micro X-ray diffraction, which is a unique non-invasive probe of both reciprocal and real space to visualize statistical fluctuations of myelin order of the sciatic nerve of Xenopus laevis. The results show that the ultrastructure period of the myelin is stabilized by large anticorrelated fluctuations at nanoscale, between hydrophobic and hydrophilic layers. The ratio between the total thickness of hydrophilic and hydrophobic layers defines the conformational parameter, which describes the different states of myelin. Our key result is that myelin in its out-of-equilibrium functional state fluctuates point-to-point between different conformations showing a correlated disorder described by a Levy distribution. As the system approaches the thermodynamic equilibrium in an aged state, the disorder loses its correlation degree and the structural fluctuation distribution changes to Gaussian. In a denatured state at low pH, it changes to a completely disordered stage. Our results aim to clarify the degradation mechanism in biological systems by associating these states with ultrastructural dynamic fluctuations at nanoscale.

  1. Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

    Science.gov (United States)

    Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

    2013-01-01

    Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

  2. Development of Self-Assembled Nanoscale Templates via Microphase Separation Induced by Polymer Brushes

    Science.gov (United States)

    Chu, Elza

    Phase separation in soft matter has been the crucial element in generating hybrid materials, such as polymer blends and mixed polymer brushes. This dissertation discusses two methods of developing self-assembled nanoscale templates via microphase separation induced by polymer brush synthesis. This work introduces a novel soft substrate approach with renewable grafting sites where polyacrylamide is "grafted through" chitosan soft substrates. The mechanism of grafting leads to ordered arrays of filament-like nanostructures spanning the chitosan-air interface. Additionally, the chemical composition of the filaments allows for post-chemical modification to change the physical properties of the filaments, and subsequently tailor surfaces for specific application. Unlike traditional materials, multi-functional or "smart" materials, such as binary polymer brushes (BPB) are capable of spontaneously changing the spatial distribution of functional groups and morphology at the surface upon external stimuli. Although promising in principle, the limited range of available complementary polymers with common non-selective solvents confines the diversity of usable materials and restricts any further advancement in the field. This dissertation also covers the fabrication and characterization of responsive nanoscale polystyrene templates or "mosaic" brushes that are capable of changing interfacial composition upon exposure to varying solvent qualities. Using a "mosaic" brush template is a unique approach that allows the fabrication of strongly immiscible polymer BPB without the need for a common solvent. The synthesis of such BPB is exemplified by two strongly immiscible polymers, i.e. polystyrene (polar) and polyacrylamide (non-polar), where polyacrylamide brush is "graft through" a Si-substrate modified with the polystyrene collapsed "mosaic" brush. The surface exhibits solvent-triggered responses, as well as application potential for anti-biofouling.

  3. Light-matter interaction physics and engineering at the nanoscale

    CERN Document Server

    Weiner, John

    2013-01-01

    This book draws together the essential elements of classical electrodynamics, surface wave physics, plasmonic materials, and circuit theory of electrical engineering to provide insight into the essential physics of nanoscale light-matter interaction and to provide design methodology for practical nanoscale plasmonic devices. A chapter on classical and quantal radiation also highlights the similarities (and differences) between the classical fields of Maxwell's equations and the wave functions of Schrodinger's equation. The aim of this chapter is to provide a semiclassical picture of atomic absorption and emission of radiation, lending credence and physical plausibility to the "rules" of standard wave-mechanical calculations.

  4. Nanoscopic morphological changes in yeast cell surfaces caused by oxidative stress: an atomic force microscopic study.

    Science.gov (United States)

    Canetta, Elisabetta; Walker, Graeme M; Adya, Ashok K

    2009-06-01

    Nanoscopic changes in the cell surface morphology of the yeasts Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354), due to their exposure to varying concentrations of hydrogen peroxide (oxidative stress), were investigated using an atomic force microscope (AFM). Increasing hydrogen peroxide concentration led to a decrease in cell viabilities and mean cell volumes, and an increase in the surface roughness of the yeasts. In addition, AFM studies revealed that oxidative stress caused cell compression in both S. cerevisiae and Schiz. pombe cells and an increase in the number of aged yeasts. These results confirmed the importance and usefulness of AFM in investigating the morphology of stressed microbial cells at the nanoscale. The results also provided novel information on the relative oxidative stress tolerance of S. cerevisiae and Schiz. pombe.

  5. Study of nanoscale structural biology using advanced particle beam microscopy

    Science.gov (United States)

    Boseman, Adam J.

    This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

  6. Abstractocyte: A Visual Tool for Exploring Nanoscale Astroglial Cells

    KAUST Repository

    Mohammed, Haneen

    2017-06-12

    This thesis presents the design and implementation of Abstractocyte, a system for the visual analysis of astrocytes, and their relation to neurons, in nanoscale volumes of brain tissue. Astrocytes are glial cells, i.e., non-neuronal cells that support neurons and the nervous system. Even though glial cells make up around 50 percent of all cells in the mammalian brain, so far they have been far less studied than neurons. Nevertheless, the study of astrocytes has immense potential for understanding brain function. However, the complex and widely-branching structure of astrocytes requires high-resolution electron microscopy imaging and makes visualization and analysis challenging. Using Abstractocyte, biologists can explore the morphology of astrocytes at various visual abstraction levels, while simultaneously analyzing neighboring neurons and their connectivity. We define a novel, conceptual 2D abstraction space for jointly visualizing astrocytes and neurons. Neuroscientists can choose a joint visualization as a specific point in that 2D abstraction space. Dragging this point allows them to smoothly transition between different abstraction levels in an intuitive manner. We describe the design of Abstractocyte, and present three case studies in which neuroscientists have successfully used our system to assess astrocytic coverage of synapses, glycogen distribution in relation to synapses, and astrocytic-mitochondria coverage.

  7. Nanoscale thermal-mechanical probe determination of 'softening transitions' in thin polymer films

    International Nuclear Information System (INIS)

    Zhou Jing; Berry, Brian; Douglas, Jack F; Karim, Alamgir; Snyder, Chad R; Soles, Christopher

    2008-01-01

    We report a quantitative study of the softening behavior of glassy polystyrene (PS) films at length scales on the order of 100 nm using nano-thermomechanometry (nano-TM), an emerging scanning probe technique in which a highly doped silicon atomic force microscopy (AFM) tip is resistively heated on the surface of a polymer film. The apparent 'softening temperature' T s of the film is found to depend on the logarithm of the square root of the thermal ramping rate R. This relation allows us to estimate a quasi-equilibrium (or zero rate) softening transition temperature T s0 by extrapolation. We observe marked shifts of T s0 with decreasing film thickness, but the nature of these shifts, and even their sign, depend strongly on both the thermal and mechanical properties of the supporting substrate. Finite element simulations suggest that thin PS films on rigid substrates with large thermal conductivities lead to increasing T s0 with decreasing film thickness, whereas softer, less thermally conductive substrates promote reductions in T s0 . Experimental observations on a range of substrates confirm this behavior and indicate a complicated interplay between the thermal and mechanical properties of the thin PS film and the substrate. This study directly points to relevant factors for quantitative measurements of thermophysical properties of materials at the nanoscale using this nano-TM based method.

  8. Multiple-scanning-probe tunneling microscope with nanoscale positional recognition function.

    Science.gov (United States)

    Higuchi, Seiji; Kuramochi, Hiromi; Laurent, Olivier; Komatsubara, Takashi; Machida, Shinichi; Aono, Masakazu; Obori, Kenichi; Nakayama, Tomonobu

    2010-07-01

    Over the past decade, multiple-scanning-probe microscope systems with independently controlled probes have been developed for nanoscale electrical measurements. We developed a quadruple-scanning-probe tunneling microscope (QSPTM) that can determine and control the probe position through scanning-probe imaging. The difficulty of operating multiple probes with submicrometer precision drastically increases with the number of probes. To solve problems such as determining the relative positions of the probes and avoiding of contact between the probes, we adopted sample-scanning methods to obtain four images simultaneously and developed an original control system for QSPTM operation with a function of automatic positional recognition. These improvements make the QSPTM a more practical and useful instrument since four images can now be reliably produced, and consequently the positioning of the four probes becomes easier owing to the reduced chance of accidental contact between the probes.

  9. Morphologically different WO3 nanocrystals in photoelectrochemical water oxidation

    International Nuclear Information System (INIS)

    Biswas, Soumya Kanti; Baeg, Jin-Ook; Moon, Sang-Jin; Kong, Ki-jeong; So, Won-Wook

    2012-01-01

    Different morphologies of WO 3 nanocrystals such as nanorods and nanoplates have been obtained under hydrothermal conditions using ammonium metatungstate as the precursor in presence of different organic acids such as citric, oxalic, and tartaric acid in the reaction medium. Detailed characterization of the crystal structure, particle morphology, and optical band gap of the synthesized powders have been done by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and solid-state UV–visible spectroscopy study. The as-synthesized materials are WO 3 hydrates with orthorhombic phase which transform to the hexagonal WO 3 through dehydration upon heating at 350 °C. The resultant products are crystalline with nanoscale dimensions. Finally, the photoactivity of the synthesized materials annealed at 500 °C has been compared employing in photoelectrochemical water oxidation under the illumination of AM 1.5G simulated solar light (100 mWcm −2 ). The photocurrent measurements upon irradiation of light exhibit obvious photocatalytic activity with a photocurrent of about 0.77, 0.61, and 0.65 mAcm −2 for the WO 3 film derived with the oxalic acid, tartaric, and citric acid assisting agents, respectively, at 1.8 V versus Ag/AgCl electrode.

  10. Morphology Formation in PC/ABS Blends during Thermal Processing and the Effect of the Viscosity Ratio of Blend Partners

    Directory of Open Access Journals (Sweden)

    Stefanie Bärwinkel

    2016-08-01

    Full Text Available Morphology formation during compounding, as well as injection molding of blends containing 60 wt % polycarbonate (PC and 40 wt % polybutadiene rubber-modified styrene-acrylonitrile copolymers (ABS, has been investigated by transmission electron microscopy (TEM. Profiles of the blend morphology have been recorded in injection-molded specimens and significant morphology gradients observed between their skin and core. A <10 µm thick surface layer with strongly dispersed and elongated nano-scale (streak-like styrene acrylonitrile (SAN phases and well-dispersed, isolated SAN-grafted polybutadiene rubber particles is followed by a 50–150 µm thick skin layer in which polymer morphology is characterized by lamellar SAN/ABS phases. Thickness of these lamellae increases with the distance from the specimen’s surface. In the core of the specimens the SAN-grafted polybutadiene rubber particles are exclusively present within the SAN phases, which exhibit a much coarser and less oriented, dispersed morphology compared to the skin. The effects of the viscosity of the SAN in the PC/ABS blends on phase morphologies and correlations with fracture mechanics in tensile and impact tests were investigated, including scanning electron microscopy (SEM assessment of the fracture surfaces. A model explaining the mechanisms of morphology formation during injection molding of PC/ABS blends is discussed.

  11. Energy efficiency in nanoscale synthesis using nanosecond plasmas.

    Science.gov (United States)

    Pai, David Z; Ken Ostrikov, Kostya; Kumar, Shailesh; Lacoste, Deanna A; Levchenko, Igor; Laux, Christophe O

    2013-01-01

    We report a nanoscale synthesis technique using nanosecond-duration plasma discharges. Voltage pulses 12.5 kV in amplitude and 40 ns in duration were applied repetitively at 30 kHz across molybdenum electrodes in open ambient air, generating a nanosecond spark discharge that synthesized well-defined MoO₃ nanoscale architectures (i.e. flakes, dots, walls, porous networks) upon polyamide and copper substrates. No nitrides were formed. The energy cost was as low as 75 eV per atom incorporated into a nanostructure, suggesting a dramatic reduction compared to other techniques using atmospheric pressure plasmas. These findings show that highly efficient synthesis at atmospheric pressure without catalysts or external substrate heating can be achieved in a simple fashion using nanosecond discharges.

  12. Non-Mendelian determinants of morphology in fungi.

    Science.gov (United States)

    Malagnac, Fabienne; Silar, Philippe

    2003-12-01

    Morphological plasticity is a hallmark of eumycetes. In addition to genes and environment, epigenetic factors control cell, colony and thallus forms in many species, by creating reversible switches. Current knowledge indicates that the different shapes are due to structural or regulatory heritable states of cytoplasmic components. Cellular physiology differs in the various forms, permitting adaptation to fluctuation in the environment. These switches are part of the adaptation repertoire that fungi exhibit to colonize most niches.

  13. Managing Temperature Effects in Nanoscale Adaptive Systems

    CERN Document Server

    Wolpert, David

    2012-01-01

    This book discusses new techniques for detecting, controlling, and exploiting the impacts of temperature variations on nanoscale circuits and systems.  It provides a holistic discussion of temperature management, including physical phenomena (reversal of the MOSFET temperature dependence) that have recently become problematic, along with circuit techniques for detecting, controlling, and adapting to these phenomena. A detailed discussion is also included of the general aspects of thermal-aware system design and management of temperature-induced faults. A new sensor system is described that can determine the temperature dependence as well as the operating temperature to improve system reliability.  A new method is presented to control a circuit’s temperature dependence by individually tuning pull-up and pull-down networks to their temperature-insensitive operating points. This method extends the range of supply voltages that can be made temperature-insensitive, achieving insensitivity at nominal voltage fo...

  14. Synthesis, dynamics and photophysics of nanoscale systems

    Science.gov (United States)

    Mirkovic, Tihana

    The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures. The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems. A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies. A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties. The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained

  15. 77 FR 13159 - Nanoscale Science, Engineering, and Technology Subcommittee of the Committee on Technology...

    Science.gov (United States)

    2012-03-05

    ... OFFICE OF SCIENCE AND TECHNOLOGY POLICY Nanoscale Science, Engineering, and Technology... public meeting. SUMMARY: The National Nanotechnology Coordination Office (NNCO), on behalf of the Nanoscale Science, Engineering, and Technology (NSET) Subcommittee of the Committee on Technology, National...

  16. Sensor-based monitoring and inspection of surface morphology in ultraprecision manufacturing processes

    Science.gov (United States)

    Rao, Prahalad Krishna

    measures (e.g., Fiedler number, Kirchoff index) extracted from these matrices are shown to be sensitive to evolving nano-surface morphology. For instance, we observed that prominent nanoscale morphological changes on CMP processed Cu wafers, although discernible visually, could not be tractably quantified using statistical metrology parameters, such as arithmetic average roughness (Sa), root mean square roughness (Sq), etc. In contrast, CMP induced nanoscale surface variations were captured on invoking graph theoretic topological invariants. Consequently, the graph theoretic approach can enable timely, non-contact, and in situ metrology of semiconductor wafers by obviating the need for reticent profile mapping techniques (e.g., AFM, SEM, etc.), and thereby prevent the propagation of yield losses over long production runs.

  17. Real time nanoscale structural evaluation of gold structures on Si (100) surface using in-situ transmission electron microscopy

    International Nuclear Information System (INIS)

    Rath, A.; Juluri, R. R.; Satyam, P. V.

    2014-01-01

    Transport behavior of gold nanostructures on Si(100) substrate during annealing under high vacuum has been investigated using in-situ real time transmission electron microscopy (TEM). A comparative study has been done on the morphological changes due to annealing under different vacuum environments. Au thin films of thickness ∼2.0 nm were deposited on native oxide covered silicon substrate by using thermal evaporation system. In-situ real time TEM measurements at 850 °C showed the isotropic growth of rectangular/square shaped gold-silicon alloy structures. During the growth, it is observed that the alloying occurs in liquid phase followed by transformation into the rectangular shapes. For similar system, ex-situ annealing in low vacuum (10 −2 millibars) at 850 °C showed the spherical gold nanostructures with no Au-Si alloy formation. Under low vacuum annealing conditions, the rate of formation of the oxide layer dominates the oxide desorption rate, resulting in the creation of a barrier layer between Au and Si, which restricts the inter diffusion of Au in to Si. This work demonstrates the important role of interfacial oxide layer on the growth of nanoscale Au-Si alloy structures during the initial growth. The time dependent TEM images are presented to offer a direct insight into the fundamental dynamics of the sintering process at the nanoscale

  18. Quantitative nanoscale surface voltage measurement on organic semiconductor blends

    International Nuclear Information System (INIS)

    Cuenat, Alexandre; Muñiz-Piniella, Andrés; Muñoz-Rojo, Miguel; Murphy, Craig E; Tsoi, Wing C

    2012-01-01

    We report on the validation of a method based on Kelvin probe force microscopy (KPFM) able to measure the different phases and the relative work function of polymer blend heterojunctions at the nanoscale. The method does not necessitate complex ultra-high vacuum setup. The quantitative information that can be extracted from the topography and the Kelvin probe measurements is critically analysed. Surface voltage difference can be observed at the nanoscale on poly(3-hexyl-thiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blends and dependence on the annealing condition and the regio-regularity of P3HT is observed. (paper)

  19. Structural, morphological and local electric properties of TiO2 thin films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Gyoergy, E; Pino, A Perez del; Sauthier, G; Figueras, A; Alsina, F; Pascual, J

    2007-01-01

    Titanium dioxide (TiO 2 ) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (λ = 266 nm, τ FWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO 2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters

  20. Time evolution of morphology in mechanically alloyed Fe-Cu

    KAUST Repository

    Wille, Catharina Gabriele

    2011-05-01

    Being widely accessible as well as already utilised in many applications, Fe-Cu acts as an ideal binary model alloy to elaborate the enforced nonequilibrium enhanced solubility in such a solution system that shows a limited regime of miscibility and characterised by a large positive heat of mixing. In addition to the detailed analysis of ball milled Fe-Cu powders by means of Atom Probe Tomography (APT), site specific structural analysis has been performed in this study using Transmission Electron Microscopy (TEM).In this contribution results on powders with low Cu concentrations (2.5-10 at%) are presented. Combining a ductile element (Cu, fcc) and a brittle one (Fe, bcc), striking differences in morphology were expected and found on all length-scales, depending on the mixing ratio of the two elements. However, not only could the atomic mixing of Fe and Cu be evaluated, but also the distribution of impurities, mostly stemming from the fabrication procedure. The combination of APT and TEM enables a correlation between the structural evolution and the chemical mixing during the milling process. For the first time, a clear distinction can be drawn between the morphological evolution at the surface and in the interior of the powder particles. This became possible owing to the site specific sample preparation of TEM lamellae by Focussed Ion Beam (FIB). Surprisingly, the texture arising from the ball milling process can directly be related to the classical rolling texture of cold rolled Fe. In addition, full homogeneity can be achieved even on the nano-scale for this material as shown by APT, resulting in an extended miscibility region in comparison to the equilibrium phase diagram. Grain sizes were determined by means of XRD and TEM. The strain corrected XRD results are in very good agreement with the values derived by TEM, both confirming a truly nanocrystalline structure. © 2011 Elsevier B.V.

  1. The influence of thermal and conductive temperatures in a nanoscale resonator

    Science.gov (United States)

    Hobiny, Aatef; Abbas, Ibrahim A.

    2018-06-01

    In this work, the thermoelastic interaction in a nano-scale resonator based on two-temperature Green-Naghdi model is established. The nanoscale resonator ends were simply supported. In the Laplace's domain, the analytical solution of conductivity temperature and thermodynamic temperature, the displacement and the stress components are obtained. The eigenvalue approach resorted to for solutions. In the vector-matrix differential equations form, the essential equations were written. The numerical results for all variables are presented and are illustrated graphically.

  2. Nanoscale mechanical stimulation method for quantifying C. elegans mechanosensory behavior and memory

    OpenAIRE

    Kiso, Kaori; Sugi, Takuma; Okumura, Etsuko; Igarashi, Ryuji

    2016-01-01

    Here, we establish a novel economic system to quantify C. elegans mechanosensory behavior and memory by a controllable nanoscale mechanical stimulation. Using piezoelectric sheet speaker, we can flexibly change the vibration properties at a nanoscale displacement level and quantify behavioral responses and memory under the control of each vibration property. This system will facilitate understanding of physiological aspects of C. elegans mechanosensory behavior and memory.

  3. Common Principles of Molecular Electronics and Nanoscale Electrochemistry.

    Science.gov (United States)

    Bueno, Paulo Roberto

    2018-05-24

    The merging of nanoscale electronics and electrochemistry can potentially modernize the way electronic devices are currently engineered or constructed. It is well known that the greatest challenges will involve not only miniaturizing and improving the performance of mobile devices, but also manufacturing reliable electrical vehicles, and engineering more efficient solar panels and energy storage systems. These are just a few examples of how technological innovation is dependent on both electrochemical and electronic elements. This paper offers a conceptual discussion of this central topic, with particular focus on the impact that uniting physical and chemical concepts at a nanoscale could have on the future development of electroanalytical devices. The specific example to which this article refers pertains to molecular diagnostics, i.e., devices that employ physical and electrochemical concepts to diagnose diseases.

  4. Ion concentration in micro and nanoscale electrospray emitters.

    Science.gov (United States)

    Yuill, Elizabeth M; Baker, Lane A

    2018-06-01

    Solution-phase ion transport during electrospray has been characterized for nanopipettes, or glass capillaries pulled to nanoscale tip dimensions, and micron-sized electrospray ionization emitters. Direct visualization of charged fluorophores during the electrospray process is used to evaluate impacts of emitter size, ionic strength, analyte size, and pressure-driven flow on heterogeneous ion transport during electrospray. Mass spectrometric measurements of positively- and negatively-charged proteins were taken for micron-sized and nanopipette emitters under low ionic strength conditions to further illustrate a discrepancy in solution-driven transport of charged analytes. A fundamental understanding of analyte electromigration during electrospray, which is not always considered, is expected to provide control over selective analyte depletion and enrichment, and can be harnessed for sample cleanup. Graphical abstract Fluorescence micrographs of ion migration in nanoscale pipettes while solution is electrosprayed.

  5. Nanoscale biomemory composed of recombinant azurin on a nanogap electrode

    International Nuclear Information System (INIS)

    Chung, Yong-Ho; Lee, Taek; Choi, Jeong-Woo; Park, Hyung Ju; Yun, Wan Soo; Min, Junhong

    2013-01-01

    We fabricate a nanoscale biomemory device composed of recombinant azurin on nanogap electrodes. For this, size-controllable nanogap electrodes are fabricated by photolithography, electron beam lithography, and surface catalyzed chemical deposition. Moreover, we investigate the effect of gap distance to optimize the size of electrodes for a biomemory device and explore the mechanism of electron transfer from immobilized protein to a nanogap counter-electrode. As the distance of the nanogap electrode is decreased in the nanoscale, the absolute current intensity decreases according to the distance decrement between the electrodes due to direct electron transfer, in contrast with the diffusion phenomenon of a micro-electrode. The biomemory function is achieved on the optimized nanogap electrode. These results demonstrate that the fabricated nanodevice composed of a nanogap electrode and biomaterials provides various advantages such as quantitative control of signals and exclusion of environmental effects such as noise. The proposed bioelectronics device, which could be mass-produced easily, could be applied to construct a nanoscale bioelectronics system composed of a single biomolecule. (paper)

  6. Extremely flexible nanoscale ultrathin body silicon integrated circuits on plastic.

    Science.gov (United States)

    Shahrjerdi, Davood; Bedell, Stephen W

    2013-01-09

    In recent years, flexible devices based on nanoscale materials and structures have begun to emerge, exploiting semiconductor nanowires, graphene, and carbon nanotubes. This is primarily to circumvent the existing shortcomings of the conventional flexible electronics based on organic and amorphous semiconductors. The aim of this new class of flexible nanoelectronics is to attain high-performance devices with increased packing density. However, highly integrated flexible circuits with nanoscale transistors have not yet been demonstrated. Here, we show nanoscale flexible circuits on 60 Å thick silicon, including functional ring oscillators and memory cells. The 100-stage ring oscillators exhibit the stage delay of ~16 ps at a power supply voltage of 0.9 V, the best reported for any flexible circuits to date. The mechanical flexibility is achieved by employing the controlled spalling technology, enabling the large-area transfer of the ultrathin body silicon devices to a plastic substrate at room temperature. These results provide a simple and cost-effective pathway to enable ultralight flexible nanoelectronics with unprecedented level of system complexity based on mainstream silicon technology.

  7. Nanoscale microstructural characterization of a nanobainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Timokhina, I.B., E-mail: ilana.timokhina@eng.monash.edu.au [Centre for Material and Fibre Innovation, Deakin University, Victoria 3216 (Australia); Beladi, H. [Centre for Material and Fibre Innovation, Deakin University, Victoria 3216 (Australia); Xiong, X.Y. [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Adachi, Y. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Hodgson, P.D. [Centre for Material and Fibre Innovation, Deakin University, Victoria 3216 (Australia)

    2011-08-15

    A 0.79 C-1.5 Si-1.98 Mn-0.98 Cr-0.24 Mo-1.06 Al-1.58 Co (wt.%) steel was isothermally heat treated at 200 deg. C for 10 days and 350 deg. C for 1 day to form a nanoscale bainitic microstructure consisting of nanobainitic ferrite laths with high dislocation density and retained austenite films. The microstructures of the samples were characterized by transmission electron microscopy and atom probe tomography. Despite the formation of nanoscale bainite with a high volume fraction of retained austenite in both steels, the ductility of both steels was surprisingly low. It is believed that this was associated with the formation of carbon-depleted retained austenite after isothermal transformation at 200 deg. C due to the formation of high number of Fe-C clusters and particles in the bainitic ferrite laths and carbon-enriched austenite after isothermal transformation at 350 deg. C.

  8. Modeling investigation of the stability and irradiation-induced evolution of nanoscale precipitates in advanced structural materials

    International Nuclear Information System (INIS)

    Wirth, Brian

    2015-01-01

    materials containing nanoscale precipitates. In particular, the interfacial structure of embedded nanoscale precipitates will be evaluated by electronic- and atomic-scale modeling methods, and the efficiency of the validated interfaces for trapping point defects will next be evaluated by atomic-scale modeling (e.g., determining the sink strength of the precipitates), addressing key questions related to the optimal interface characteristics to attract point defects and enhance their recombination. Kinetic models will also be developed to simulate microstructural evolution of the nanoscale features and irradiation produced defect clusters, and compared with observed microstructural changes.

  9. Modeling investigation of the stability and irradiation-induced evolution of nanoscale precipitates in advanced structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States)

    2015-04-08

    nanoscale precipitates. In particular, the interfacial structure of embedded nanoscale precipitates will be evaluated by electronic- and atomic-scale modeling methods, and the efficiency of the validated interfaces for trapping point defects will next be evaluated by atomic-scale modeling (e.g., determining the sink strength of the precipitates), addressing key questions related to the optimal interface characteristics to attract point defects and enhance their recombination. Kinetic models will also be developed to simulate microstructural evolution of the nanoscale features and irradiation produced defect clusters, and compared with observed microstructural changes.

  10. A study of estimating cutting depth for multi-pass nanoscale cutting by using atomic force microscopy

    International Nuclear Information System (INIS)

    Lin, Zone-Ching; Hsu, Ying-Chih

    2012-01-01

    This paper studies two models for estimating cutting depth of multi-pass nanoscale cutting by using an atomic force microscopy (AFM) probe. One estimates cutting depth for multi-pass nanoscale cutting by using regression equations of nanoscale contact pressure factor (NCP factor) while the other uses equation of specific down force energy (SDFE). This paper proposes taking a diamond-coated probe of AFM as the cutting tool to carry out multi-pass nanoscale cutting experiments on the surface of sapphire substrate. In the process of experimentation, different down forces are set, and the probe shape of AFM is known, then using each down force to multi-pass cutting the sapphire substrate. From the measured experimental data of a central cutting depth of the machining groove by AFM, this paper calculates the specific down force energy of each down force. The experiment results reveal that the specific down force energy of each case of multi-pass nanoscale cutting for different down forces under a probe of AFM is close to a constant value. This paper also compares the nanoscale cutting results from estimating cutting depths for each pass of multi-pass among the experimental results and the calculating results obtained by the two theories models. It is found that the model of specific down force energy can calculate cutting depths for each nanoscale cutting pass by one equation. It is easier to use than the multi-regression equations of the nanoscale contact pressure factor. Besides, the estimations of cutting depth results obtained by the model of specific down force energy are closer to that of the experiment results. It shows that the proposed specific down force energy model in this paper is an acceptable model.

  11. Morphological families in the mental lexicon

    NARCIS (Netherlands)

    Jong, Nivja Helena de

    2002-01-01

    Words can occur as constituents of other words. Some words have a high morphological productivity, in that they occur in many complex words, whereas others are morphological islands. Previous studies have found that the size of a word's morphological family can co-determine response latencies in

  12. Quantification of nanoscale density fluctuations by electron microscopy: probing cellular alterations in early carcinogenesis

    International Nuclear Information System (INIS)

    Pradhan, Prabhakar; Damania, Dhwanil; Turzhitsky, Vladimir; Subramanian, Hariharan; Backman, Vadim; Joshi, Hrushikesh M; Dravid, Vinayak P; Roy, Hemant K; Taflove, Allen

    2011-01-01

    Most cancers are curable if they are diagnosed and treated at an early stage. Recent studies suggest that nanoarchitectural changes occur within cells during early carcinogenesis and that such changes precede microscopically evident tissue alterations. It follows that the ability to comprehensively interrogate cell nanoarchitecture (e.g., macromolecular complexes, DNA, RNA, proteins and lipid membranes) could be critical to the diagnosis of early carcinogenesis. We present a study of the nanoscale mass-density fluctuations of biological tissues by quantifying their degree of disorder at the nanoscale. Transmission electron microscopy images of human tissues are used to construct corresponding effective disordered optical lattices. The properties of nanoscale disorder are then studied by statistical analysis of the inverse participation ratio (IPR) of the spatially localized eigenfunctions of these optical lattices at the nanoscale. Our results show an increase in the disorder of human colonic epithelial cells in subjects harboring early stages of colon neoplasia. Furthermore, our findings strongly suggest that increased nanoscale disorder correlates with the degree of tumorigenicity. Therefore, the IPR technique provides a practicable tool for the detection of nanoarchitectural alterations in the earliest stages of carcinogenesis. Potential applications of the technique for early cancer screening and detection are also discussed

  13. Evaluation of Chemical and Physical-morphological Factors as Potential Determinants of Biomphalaria pfeifferi (Krauss, 1848 Distribution

    Directory of Open Access Journals (Sweden)

    Utzinger Jürg

    1997-01-01

    Full Text Available This study was carried out in five sites along a small perennial river system in south-central Tanzania, which had been identified as the focus for transmission of intestinal schistosomiasis in the area. Malacological surveys preceding the study showed a focal distribution of Biomphalaria pfeifferi, intermediate host snail of Schistosoma mansoni, the snails being present in three sites but absent from the other two sites. The objective of this study was to evaluate to what extent chemical and/or physical-morphological factors determine the distribution of B. pfeifferi between these five sites. It was found that none of the chemical constituents in the waters examined were outside the tolerance range of B. pfeifferi snails. Moreover, the composition of water from B. pfeifferi-free sites was not different from that in those sites where snails occurred. Furthermore, none of the physical-morphological constituents seemed likely to be a determinant for the absence of B. pfeifferi. In view of these findings, and those of previous studies, it is concluded that the focal distribution of B. pfeifferi cannot be associated with a single environmental factor and is rather the result of more complex interactions of habitat factors

  14. Crystallization of high-strength nano-scale leucite glass-ceramics.

    Science.gov (United States)

    Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

    2013-11-01

    Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (pglass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Development of Nanoscale Graphitic Devices and The Transport Characterization

    International Nuclear Information System (INIS)

    Gunasekaran, Venugopal

    2011-02-01

    This dissertation describes the development of graphitic based nanoscale devices with its fabrication and transport characterization results. It covers graphite nano-scale stacked-junctions fabricated using focused ion beam (FIB) 3-D etching technique, a single layer graphite layer (graphene) preparation and its electrical transport characterization results and the synthesis and investigation of electrical transport behavior of graphene oxide based thin film devices. The first chapter describes the basic information about the carbon family in detail in which the electronic properties and structure of graphite, graphene and graphene oxide are discussed. In addition, the necessity of developing nanoscale graphitic devices is given. The second chapter explains the experimental techniques used in this research for fabricating nanoscale devices which includes focused ion beam 3-D fabrication procedures, mechanical exfoliation technique and photolithographic methods. In third chapter, we have reported the results on temperature dependence of graphite planar-type structures fabricated along ab-plane. In the fourth and fifth chapters, the fabrication and electrical transport characteristics of large in-plane area graphite planar-type structures (fabricated along ab-plane and c-axis) were discussed and their transport anisotropy properties were investigated briefly. In the sixth chapter, we focused the fabrication of the submicron sized graphite stacked junctions and their electrical transport characterization studies. In which, FIB was used to fabricated the submicron junctions with various in-plane area (with same stack height) are and their transport characteristics were compared. The seventh chapter reports investigation of electrical transport results of nanoscale graphite stacked-junctions in which the temperature dependent transport (R-T) studies, current-voltage measurements for the various in-plane areas and for various stack height samples were analyzed. The

  16. The synthesis and properties of nanoscale ionic materials

    KAUST Repository

    Rodriguez, Robert Salgado; Herrer, Rafael; Bourlinos, Athanasios B.; Li, Ruipeng; Amassian, Aram; Archer, Lynden A.; Giannelis, Emmanuel P.

    2010-01-01

    In this article we discuss the effect of constituents on structure, flow, and thermal properties of nanoscale ionic materials (NIMs). NIMs are a new class of nanohybrids consisting of a nanometer-sized core, a charged corona covalently attached

  17. The Nanoscale Observation of the Three-Dimensional Structures of Neurosynapses, Membranous Conjunctions Between Cultured Hippocampal Neurons and Their Significance in the Development of Epilepsy.

    Science.gov (United States)

    Sun, Lan; Jiang, Shuang; Tang, Xianhua; Zhang, Yingge; Qin, Luye; Jiang, Xia; Yu, Albert Cheung Hoi

    2016-12-01

    The nanoscale three-dimensional structures of neurosynapses are unknown, and the neuroanatomical basis of epilepsy remains to be elucidated. Here, we studied the nanoscale three-dimensional synapses between hippocampal neurons, and membranous conjunctions between neurons were found with atomic force microscopy (AFM) and confirmed by transmission electron microscope (TEM), and their pathophysiological significance was primarily investigated. The neurons and dendrites were marked by MAP-2, axons by neurofilament 200, and synapses by synapsin I immunological staining. In the synapsin I-positive neurite ends of the neurons positively stained with MAP-2 and neurofilament 200, neurosynapses with various nanoscale morphology and structure could be found by AFM. The neurosynapses had typical three-dimensional structures of synaptic triplet including the presynaptic neurite end, synaptic cleft of 30 ∼ 40 in chemical synapses and 2 ∼ 6 nm in electrical ones, the postsynaptic neurite or dendrite spine, the typical neurite end button, the distinct pre- and postsynaptic membranes, and the obvious thickening of the postsynaptic membranes or neurites. Some membranous connections including membrane-like junctions (MLJ) and fiber-tube links (FTL) without triplet structures and cleft were found between neurons. The development frequencies of the two membranous conjunctions increased while those of the synaptic conjunctions decreased between the neurons from Otx1 knock-out mice in comparison with those between the neurons from normal mice. These results suggested that the neuroanatomical basis of Otx1 knock-out epilepsy is the combination of the decreased synaptic conjunctions and the increased membranous conjunctions.

  18. Molecular and Nanoscale Engineering of High Efficiency Excitonic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jenekhe, Samson A. [Univ. of Washington, Seattle, WA (United States); Ginger, David S. [Univ. of Washington, Seattle, WA (United States); Cao, Guozhong [Univ. of Washington, Seattle, WA (United States)

    2016-01-15

    We combined the synthesis of new polymers and organic-inorganic hybrid materials with new experimental characterization tools to investigate bulk heterojunction (BHJ) polymer solar cells and hybrid organic-inorganic solar cells during the 2007-2010 period (phase I) of this project. We showed that the bulk morphology of polymer/fullerene blend solar cells could be controlled by using either self-assembled polymer semiconductor nanowires or diblock poly(3-alkylthiophenes) as the light-absorbing and hole transport component. We developed new characterization tools in-house, including photoinduced absorption (PIA) spectroscopy, time-resolved electrostatic force microscopy (TR-EFM) and conductive and photoconductive atomic force microscopy (c-AFM and pc-AFM), and used them to investigate charge transfer and recombination dynamics in polymer/fullerene BHJ solar cells, hybrid polymer-nanocrystal (PbSe) devices, and dye-sensitized solar cells (DSSCs); we thus showed in detail how the bulk photovoltaic properties are connected to the nanoscale structure of the BHJ polymer solar cells. We created various oxide semiconductor (ZnO, TiO2) nanostructures by solution processing routes, including hierarchical aggregates and nanorods/nanotubes, and showed that the nanostructured photoanodes resulted in substantially enhanced light-harvesting and charge transport, leading to enhanced power conversion efficiency of dye-sensitized solar cells.

  19. Strain Imaging of Nanoscale Semiconductor Heterostructures with X-Ray Bragg Projection Ptychography

    Science.gov (United States)

    Holt, Martin V.; Hruszkewycz, Stephan O.; Murray, Conal E.; Holt, Judson R.; Paskiewicz, Deborah M.; Fuoss, Paul H.

    2014-04-01

    We report the imaging of nanoscale distributions of lattice strain and rotation in complementary components of lithographically engineered epitaxial thin film semiconductor heterostructures using synchrotron x-ray Bragg projection ptychography (BPP). We introduce a new analysis method that enables lattice rotation and out-of-plane strain to be determined independently from a single BPP phase reconstruction, and we apply it to two laterally adjacent, multiaxially stressed materials in a prototype channel device. These results quantitatively agree with mechanical modeling and demonstrate the ability of BPP to map out-of-plane lattice dilatation, a parameter critical to the performance of electronic materials.

  20. Nanoscale MOS devices: device parameter fluctuations and low-frequency noise (Invited Paper)

    Science.gov (United States)

    Wong, Hei; Iwai, Hiroshi; Liou, J. J.

    2005-05-01

    It is well-known in conventional MOS transistors that the low-frequency noise or flicker noise is mainly contributed by the trapping-detrapping events in the gate oxide and the mobility fluctuation in the surface channel. In nanoscale MOS transistors, the number of trapping-detrapping events becomes less important because of the large direct tunneling current through the ultrathin gate dielectric which reduces the probability of trapping-detrapping and the level of leakage current fluctuation. Other noise sources become more significant in nanoscale devices. The source and drain resistance noises have greater impact on the drain current noise. Significant contribution of the parasitic bipolar transistor noise in ultra-short channel and channel mobility fluctuation to the channel noise are observed. The channel mobility fluctuation in nanoscale devices could be due to the local composition fluctuation of the gate dielectric material which gives rise to the permittivity fluctuation along the channel and results in gigantic channel potential fluctuation. On the other hand, the statistical variations of the device parameters across the wafer would cause the noise measurements less accurate which will be a challenge for the applicability of analytical flicker noise model as a process or device evaluation tool for nanoscale devices. Some measures for circumventing these difficulties are proposed.

  1. Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

    DEFF Research Database (Denmark)

    Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.

    2009-01-01

    Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K...

  2. Electrostatic potential fluctuation induced by charge discreteness in a nanoscale trench

    International Nuclear Information System (INIS)

    Lee, Taesang; Kim, S. S.; Jho, Y. S.; Park, Gunyoung; Chang, C. S.

    2007-01-01

    A simplified two-dimensional Monte Carlo simulation is performed to estimate the charging potential fluctuations caused by strong binary Coulomb interactions between discrete charged particles in nanometer scale trenches. It is found that the discrete charge effect can be an important part of the nanoscale trench research, inducing scattering of ion trajectories in a nanoscale trench by a fluctuating electric field. The effect can enhance the ion deposition on the side walls and disperse the material contact energy of the incident ions, among others

  3. Distribution of Type I Collagen Morphologies in Bone: Relation to Estrogen Depletion

    Science.gov (United States)

    Wallace, Joseph M.; Erickson, Blake; Les, Clifford M.; Orr, Bradford G.; Holl, Mark M. Banaszak

    2009-01-01

    Bone is an amazing material evolved by nature to elegantly balance structural and metabolic needs in the body. Bone health is an integral part of overall health, but our lack of understanding of the ultrastructure of healthy bone precludes us from knowing how disease may impact nanoscale properties in this biological material. Here, we show that quantitative assessments of a distribution of Type I collagen fibril morphologies can be made using atomic force microscopy (AFM). We demonstrate that normal bone contains a distribution of collagen fibril morphologies and that changes in this distribution can be directly related to disease state. Specifically, by monitoring changes in the collagen fibril distribution of sham-operated and estrogen-depleted sheep, we have shown the ability to detect estrogen-deficiency-induced changes in Type I collagen in bone. This discovery provides new insight into the ultrastructure of bone as a tissue and the role of material structure in bone disease. The observation offers the possibility of a much-needed in vitro procedure to complement the current methods used to diagnose osteoporosis and other bone disease. PMID:19932773

  4. Surface-spin magnetism of antiferromagnetic NiO in nanoparticle and bulk morphology

    International Nuclear Information System (INIS)

    Jagodic, M; Jaglicic, Z; Jelen, A; Dolinsek, J; Lee, Jin Bae; Kim, Hae Jin; Kim, Young-Min

    2009-01-01

    The surface-spin magnetism of the antiferromagnetic (AFM) material NiO in nanoparticle and bulk morphology was investigated by magnetic measurements (temperature-dependent zero-field-cooled (zfc) and field-cooled (fc) dc susceptibility, ac susceptibility and zfc and fc hysteresis loops). We addressed the question of whether the multisublattice ordering of the uncompensated surface spins and the exchange bias (EB) effect are only present in the nanoparticles, originating from their high surface-to-volume ratio or if these surface phenomena are generally present in the AFM materials regardless of their bulky or nanoparticle morphology, but the effect is just too small to be detected experimentally in the bulk due to a very small surface magnetization. Performing experiments on the NiO nanoparticles of different sizes and bulk NiO grains, we show that coercivity enhancement and hysteresis loop shift in the fc experiments, considered to be the key experimental manifestations of multisublattice ordering and the EB effect, are true nanoscale phenomena only present in the nanoparticles and absent in the bulk.

  5. Quantum dynamics in nanoscale magnets in dissipative environments

    NARCIS (Netherlands)

    Miyashita, S; Saito, K; Kobayashi, H.; de Raedt, H.A.

    2000-01-01

    In discrete energy structure of nanoscale magnets, nonadiabatic transitions at avoided level crossings lead to fundamental processes of dynamics of magnetizations. The thermal environment causes dissipative effects on these processes. In this paper we review the features of the nonadiabatic

  6. Synthesis of nanoscale copper nitride thin film and modification of the surface under high electronic excitation.

    Science.gov (United States)

    Ghosh, S; Tripathi, A; Ganesan, V; Avasthi, D K

    2008-05-01

    Nanoscale (approximately 90 nm) Copper nitride (Cu3N) films are deposited on borosilicate glass and Si substrates by RF sputtering technique in the reactive environment of nitrogen gas. These films are irradiated with 200 MeV Au15+ ions from Pelletron accelerator in order to modify the surface by high electronic energy deposition of heavy ions. Due to irradiation (i) at incident ion fluence of 1 x 10(12) ions/cm2 enhancement of grains, (ii) at 5 x 10912) ions/cm2 mass transport on the films surface, (iii) at 2 x 10(13) ions/cm2 line-like features on Cu3N/glass and nanometallic structures on Cu3N/Si surface are observed. The surface morphology is examined by atomic force microscope (AFM). All results are explained on the basis of a thermal spike model of ion-solid interaction.

  7. 2D Quantum Mechanical Study of Nanoscale MOSFETs

    Science.gov (United States)

    Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, B.; Kwak, Dochan (Technical Monitor)

    2000-01-01

    With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density-gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions and oxide tunneling are treated on an equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. We present the results of our simulations of MIT 25, 50 and 90 nm "well-tempered" MOSFETs and compare them to those of classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. Surprisingly, the self-consistent potential profile shows lower injection barrier in the channel in quantum case. These results are qualitatively consistent with ID Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and subthreshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.

  8. Selective nanoscale growth of lattice mismatched materials

    Science.gov (United States)

    Lee, Seung-Chang; Brueck, Steven R. J.

    2017-06-20

    Exemplary embodiments provide materials and methods of forming high-quality semiconductor devices using lattice-mismatched materials. In one embodiment, a composite film including one or more substantially-single-particle-thick nanoparticle layers can be deposited over a substrate as a nanoscale selective growth mask for epitaxially growing lattice-mismatched materials over the substrate.

  9. Tunable all-optical plasmonic rectifier in nanoscale metal-insulator-metal waveguides.

    Science.gov (United States)

    Xu, Yi; Wang, Xiaomeng; Deng, Haidong; Guo, Kangxian

    2014-10-15

    We propose a tunable all-optical plasmonic rectifier based on the nonlinear Fano resonance in a metal-insulator-metal plasmonic waveguide and cavities coupling system. We develop a theoretical model based on the temporal coupled-mode theory to study the device physics of the nanoscale rectifier. We further demonstrate via the finite difference time domain numerical experiment that our idea can be realized in a plasmonic system with an ultracompact size of ~120×800  nm². The tunable plasmonic rectifier could facilitate the all-optical signal processing in nanoscale.

  10. On ripples and rafts: Curvature induced nanoscale structures in lipid membranes

    International Nuclear Information System (INIS)

    Schmid, Friederike; Dolezel, Stefan; Meinhardt, Sebastian; Lenz, Olaf

    2014-01-01

    We develop an elastic theory that predicts the spontaneous formation of nanoscale structures in lipid bilayers which locally phase separate between two phases with different spontaneous monolayer curvature. The theory rationalizes in a unified manner the observation of a variety of nanoscale structures in lipid membranes: Rippled states in one-component membranes, lipid rafts in multicomponent membranes. Furthermore, we report on recent observations of rippled states and rafts in simulations of a simple coarse-grained model for lipid bilayers, which are compatible with experimental observations and with our elastic model

  11. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-12

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  12. FDTD based model of ISOCT imaging for validation of nanoscale sensitivity (Conference Presentation)

    Science.gov (United States)

    Eid, Aya; Zhang, Di; Yi, Ji; Backman, Vadim

    2017-02-01

    Many of the earliest structural changes associated with neoplasia occur on the micro and nanometer scale, and thus appear histologically normal. Our group has established Inverse Spectroscopic OCT (ISOCT), a spectral based technique to extract nanoscale sensitive metrics derived from the OCT signal. Thus, there is a need to model light transport through relatively large volumes (< 50 um^3) of media with nanoscale level resolution. Finite Difference Time Domain (FDTD) is an iterative approach which directly solves Maxwell's equations to robustly estimate the electric and magnetic fields propagating through a sample. The sample's refractive index for every spatial voxel and wavelength are specified upon a grid with voxel sizes on the order of λ/20, making it an ideal modelling technique for nanoscale structure analysis. Here, we utilize the FDTD technique to validate the nanoscale sensing ability of ISOCT. The use of FDTD for OCT modelling requires three components: calculating the source beam as it propagates through the optical system, computing the sample's scattered field using FDTD, and finally propagating the scattered field back through the optical system. The principles of Fourier optics are employed to focus this interference field through a 4f optical system and onto the detector. Three-dimensional numerical samples are generated from a given refractive index correlation function with known parameters, and subsequent OCT images and mass density correlation function metrics are computed. We show that while the resolvability of the OCT image remains diffraction limited, spectral analysis allows nanoscale sensitive metrics to be extracted.

  13. Nanoscale semiconducting silicon as a nutritional food additive

    Energy Technology Data Exchange (ETDEWEB)

    Canham, L T [pSiNutria Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom)

    2007-05-09

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study.

  14. Nanoscale semiconducting silicon as a nutritional food additive

    International Nuclear Information System (INIS)

    Canham, L T

    2007-01-01

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study

  15. Visualizing copper assisted graphene growth in nanoscale

    Science.gov (United States)

    Rosmi, Mohamad Saufi; Yusop, Mohd Zamri; Kalita, Golap; Yaakob, Yazid; Takahashi, Chisato; Tanemura, Masaki

    2014-01-01

    Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp2 hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction. PMID:25523645

  16. Improving Neural Recording Technology at the Nanoscale

    Science.gov (United States)

    Ferguson, John Eric

    Neural recording electrodes are widely used to study normal brain function (e.g., learning, memory, and sensation) and abnormal brain function (e.g., epilepsy, addiction, and depression) and to interface with the nervous system for neuroprosthetics. With a deep understanding of the electrode interface at the nanoscale and the use of novel nanofabrication processes, neural recording electrodes can be designed that surpass previous limits and enable new applications. In this thesis, I will discuss three projects. In the first project, we created an ultralow-impedance electrode coating by controlling the nanoscale texture of electrode surfaces. In the second project, we developed a novel nanowire electrode for long-term intracellular recordings. In the third project, we created a means of wirelessly communicating with ultra-miniature, implantable neural recording devices. The techniques developed for these projects offer significant improvements in the quality of neural recordings. They can also open the door to new types of experiments and medical devices, which can lead to a better understanding of the brain and can enable novel and improved tools for clinical applications.

  17. Fourth International Conference on Nanoscale Magnetism

    CERN Document Server

    Aktas, Bekir; Advances in Nanoscale Magnetism

    2009-01-01

    The book aims to provide an overview of recent progress in the understanding of magnetic properties in nanoscale through recent results of various theoretical and experimental investigations. The papers describe a wide range of physical aspects, together with theoretical and experimental methods. It is of central interest to researchers and specialists in magnetism and magnetic materials science, both in academic and industrial research, as well as advanced students.

  18. Linear arrangement of nano-scale magnetic particles formed in Cu-Fe-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung, E-mail: k3201s@hotmail.co [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeda, Mahoto [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeguchi, Masaki [Advanced Electron Microscopy Group, National Institute for Materials Science (NIMS), Sakura 3-13, Tsukuba, 305-0047 (Japan); Bae, Dong-Sik [School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam, 641-773 (Korea, Republic of)

    2010-04-30

    The structural evolution of nano-scale magnetic particles formed in Cu-Fe-Ni alloys on isothermal annealing at 878 K has been investigated by means of transmission electron microscopy (TEM), electron dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS) and field-emission scanning electron microscopy (FE-SEM). Phase decomposition of Cu-Fe-Ni occurred after an as-quenched specimen received a short anneal, and nano-scale magnetic particles were formed randomly in the Cu-rich matrix. A striking feature that two or more nano-scale particles with a cubic shape were aligned linearly along <1,0,0> directions was observed, and the trend was more pronounced at later stages of the precipitation. Large numbers of <1,0,0> linear chains of precipitates extended in three dimensions in late stages of annealing.

  19. Nanoscale Test Strips for Multiplexed Blood Analysis, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of our nanoscale test strips, or nanostrips, is to provide rapid, low-cost, powerful multiplexed analyses in a diminutive form so that whole body health...

  20. NeuroLines: A Subway Map Metaphor for Visualizing Nanoscale Neuronal Connectivity.

    Science.gov (United States)

    Al-Awami, Ali K; Beyer, Johanna; Strobelt, Hendrik; Kasthuri, Narayanan; Lichtman, Jeff W; Pfister, Hanspeter; Hadwiger, Markus

    2014-12-01

    We present NeuroLines, a novel visualization technique designed for scalable detailed analysis of neuronal connectivity at the nanoscale level. The topology of 3D brain tissue data is abstracted into a multi-scale, relative distance-preserving subway map visualization that allows domain scientists to conduct an interactive analysis of neurons and their connectivity. Nanoscale connectomics aims at reverse-engineering the wiring of the brain. Reconstructing and analyzing the detailed connectivity of neurons and neurites (axons, dendrites) will be crucial for understanding the brain and its development and diseases. However, the enormous scale and complexity of nanoscale neuronal connectivity pose big challenges to existing visualization techniques in terms of scalability. NeuroLines offers a scalable visualization framework that can interactively render thousands of neurites, and that supports the detailed analysis of neuronal structures and their connectivity. We describe and analyze the design of NeuroLines based on two real-world use-cases of our collaborators in developmental neuroscience, and investigate its scalability to large-scale neuronal connectivity data.

  1. NeuroLines: A Subway Map Metaphor for Visualizing Nanoscale Neuronal Connectivity

    KAUST Repository

    Al-Awami, Ali K.; Beyer, Johanna; Strobelt, Hendrik; Kasthuri, Narayanan; Lichtman, Jeff W.; Pfister, Hanspeter; Hadwiger, Markus

    2014-01-01

    We present NeuroLines, a novel visualization technique designed for scalable detailed analysis of neuronal connectivity at the nanoscale level. The topology of 3D brain tissue data is abstracted into a multi-scale, relative distance-preserving subway map visualization that allows domain scientists to conduct an interactive analysis of neurons and their connectivity. Nanoscale connectomics aims at reverse-engineering the wiring of the brain. Reconstructing and analyzing the detailed connectivity of neurons and neurites (axons, dendrites) will be crucial for understanding the brain and its development and diseases. However, the enormous scale and complexity of nanoscale neuronal connectivity pose big challenges to existing visualization techniques in terms of scalability. NeuroLines offers a scalable visualization framework that can interactively render thousands of neurites, and that supports the detailed analysis of neuronal structures and their connectivity. We describe and analyze the design of NeuroLines based on two real-world use-cases of our collaborators in developmental neuroscience, and investigate its scalability to large-scale neuronal connectivity data.

  2. NeuroLines: A Subway Map Metaphor for Visualizing Nanoscale Neuronal Connectivity

    KAUST Repository

    Al-Awami, Ali K.

    2014-12-31

    We present NeuroLines, a novel visualization technique designed for scalable detailed analysis of neuronal connectivity at the nanoscale level. The topology of 3D brain tissue data is abstracted into a multi-scale, relative distance-preserving subway map visualization that allows domain scientists to conduct an interactive analysis of neurons and their connectivity. Nanoscale connectomics aims at reverse-engineering the wiring of the brain. Reconstructing and analyzing the detailed connectivity of neurons and neurites (axons, dendrites) will be crucial for understanding the brain and its development and diseases. However, the enormous scale and complexity of nanoscale neuronal connectivity pose big challenges to existing visualization techniques in terms of scalability. NeuroLines offers a scalable visualization framework that can interactively render thousands of neurites, and that supports the detailed analysis of neuronal structures and their connectivity. We describe and analyze the design of NeuroLines based on two real-world use-cases of our collaborators in developmental neuroscience, and investigate its scalability to large-scale neuronal connectivity data.

  3. Morphological Characterization and Determination of Aflatoxin-Production Potentials of Aspergillus flavus Isolated from Maize and Soil in Kenya

    Directory of Open Access Journals (Sweden)

    Matome Gabriel Thathana

    2017-09-01

    Full Text Available This study aimed at morphologically identifying Aspergillus flavus in soil and maize and at determining their aflatoxin-producing potentials. Five hundred and fourteen isolates obtained from maize and soil in Kenya were cultivated on Czapeck Dox Agar, Malt Extract Agar, Sabouraud Dextrose Agar, Potato Dextrose Agar, and Rose-Bengal Chloramphenicol Agar. Isolates were identified using macro-morphological characteristics. Micromorphological characteristics were determined using slide cultures. Aflatoxin production was determined by direct visual determination of the UV fluorescence of colonies on Coconut Agar Medium, Yeast Extract Sucrose agar, and Yeast Extract Cyclodextrin Sodium Deoxycholate agar and by Thin Layer Chromatography. Forty-three presumptive A. flavus isolates were identified; aflatoxin was detected in 23% of the isolates by UV fluorescence screening and in 30% by Thin-Layer Chromatography (TLC. The aflatoxins produced were: aflatoxin B1 (AFB1, aflatoxin B2 (AFB2, and aflatoxin G1 (AFG1; some isolates produced only AFB1, whereas others produced either AFB1 and AFB2 or AFB1 and AFG1. The highest incidence of A. flavus (63% and aflatoxin production (28% was recorded in samples from Makueni District. Isolates from Uasin Gishu (21% and Nyeri (5% were non-aflatoxigenic. Bungoma District recorded 11% positive isolates of which 2% were aflatoxin producers. The occurrence of aflatoxin-producing A. flavus emphasises the need for measures to eliminate their presence in food crops.

  4. Super-Resolution Molecular and Functional Imaging of Nanoscale Architectures in Life and Materials Science

    KAUST Repository

    Habuchi, Satoshi

    2014-06-12

    Super-resolution (SR) fluorescence microscopy has been revolutionizing the way in which we investigate the structures, dynamics, and functions of a wide range of nanoscale systems. In this review, I describe the current state of various SR fluorescence microscopy techniques along with the latest developments of fluorophores and labeling for the SR microscopy. I discuss the applications of SR microscopy in the fields of life science and materials science with a special emphasis on quantitative molecular imaging and nanoscale functional imaging. These studies open new opportunities for unraveling the physical, chemical, and optical properties of a wide range of nanoscale architectures together with their nanostructures and will enable the development of new (bio-)nanotechnology.

  5. Experimental and molecular dynamics characterization of dense micro emulsion systems morphology, conductivity and SAXS

    NARCIS (Netherlands)

    Negro, E.; Latsuzbaia, R.; de Vries, A. H.; Koper, G. J. M.

    2014-01-01

    Microemulsions are exciting systems that are promising as tuneable self-assembling templating reaction vessels at the nanoscale. Determination of the nano-structure of microemulsions is, however, not trivial, and there are fundamental questions regarding their design. We were able to reproduce

  6. Determination of the hydrodynamic and morphological parameters of the Luyano River using radiotracer techniques

    International Nuclear Information System (INIS)

    Valcarcel, Lino; Alberro, Nancy; Rodriguez, Maydel; Herrero, Zahily; Borroto, Jorge; Hernandez, Anel; Dominguez, Judith; Derivet, Milagros; Flores, Pedro; Cuesta, Jaime; Griffith, Jose

    2011-01-01

    The hydrodynamic and morphological parameters (the times of travel, velocities and flowrates of the waters, and the average widths, cross sections and depths) in the middle segment of the river Luyano were determined combining the employment of sodium pertechnectate (Na 99m TcO 4 ) as radiotracer with other conventional techniques. The results were used for the calibration of the expanded Streeter and Phelps model of the river. In the work, the methodology and the main results obtained during the journey realized between the second fortnight of March and the first of April 2009 are presented. (Author)

  7. TUTORIAL: Focused-ion-beam-based rapid prototyping of nanoscale magnetic devices

    Science.gov (United States)

    Khizroev, S.; Litvinov, D.

    2004-03-01

    In this tutorial, focused-ion-beam (FIB)-based fabrication is considered from a very unconventional angle. FIB is considered not as a fabrication tool that can be used for mass production of electronic devices, similar to optical and E-beam—based lithography, but rather as a powerful tool to rapidly fabricate individual nanoscale magnetic devices for prototyping future electronic applications. Among the effects of FIB-based fabrication of magnetic devices, the influence of Ga+-ion implantation on magnetic properties is presented. With help of magnetic force microscopy (MFM), it is shown that there is a critical doze of ions that a magnetic material can be exposed to without experiencing a change in the magnetic properties. Exploiting FIB from such an unconventional perspective is especially favourable today when the future of so many novel technologies depends on the ability to rapidly fabricate prototype nanoscale magnetic devices. As one of the most illustrative examples, the multi-billion-dollar data storage industry is analysed as the technology field that strongly benefited from implementing FIB in the above-described role. The essential role of FIB in the most recent trend of the industry towards perpendicular magnetic recording is presented. Moreover, other emerging and fast-growing technologies are considered as examples of nanoscale technologies whose future could strongly depend on the implementation of FIB in the role of a nanoscale fabrication tool for rapid prototyping. Among the other described technologies are 'ballistic' magnetoresistance, patterned magnetic media, magnetoresistive RAM (MRAM), and magnetic force microscopy.

  8. New insights into micro/nanoscale combined probes (nanoAuger, μXPS) to characterize Ag/Au@SiO2 core-shell assemblies

    Science.gov (United States)

    Ledeuil, J. B.; Uhart, A.; Soulé, S.; Allouche, J.; Dupin, J. C.; Martinez, H.

    2014-09-01

    This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (~12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies.This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming

  9. Nano-scale Materials and Nano-technology Processes in Environmental Protection

    International Nuclear Information System (INIS)

    Vissokov, Gh; Tzvetkoff, T.

    2003-01-01

    A number of environmental and energy technologies have benefited substantially from nano-scale technology: reduced waste and improved energy efficiency; environmentally friendly composite structures; waste remediation; energy conversion. In this report examples of current achievements and paradigm shifts are presented: from discovery to application; a nano structured materials; nanoparticles in the environment (plasma chemical preparation); nano-porous polymers and their applications in water purification; photo catalytic fluid purification; hierarchical self-assembled nano-structures for adsorption of heavy metals, etc. Several themes should be considered priorities in developing nano-scale processes related to environmental management: 1. To develop understanding and control of relevant processes, including protein precipitation and crystallisation, desorption of pollutants, stability of colloidal dispersion, micelle aggregation, microbe mobility, formation and mobility of nanoparticles, and tissue-nanoparticle interaction. Emphasis should be given to processes at phase boundaries (solid-liquid, solid-gas, liquid-gas) that involve mineral and organic soil components, aerosols, biomolecules (cells, microbes), bio tissues, derived components such as bio films and membranes, and anthropogenic additions (e.g. trace and heavy metals); 2. To carry out interdisciplinary research that initiates Noel approaches and adopts new methods for characterising surfaces and modelling complex systems to problems at interfaces and other nano-structures in the natural environment, including those involving biological or living systems. New technological advances such as optical traps, laser tweezers, and synchrotrons are extending examination of molecular and nano-scale processes to the single-molecule or single-cell level; 3. To integrate understanding of the roles of molecular and nano-scale phenomena and behaviour at the meso- and/or macro-scale over a period of time

  10. Nanotechnology and the public: Effectively communicating nanoscale science and engineering concepts

    International Nuclear Information System (INIS)

    Castellini, O. M.; Walejko, G. K.; Holladay, C. E.; Theim, T. J.; Zenner, G. M.; Crone, W. C.

    2007-01-01

    Researchers are faced with challenges when addressing the public on concepts and applications associated with nanotechnology. The goal of our work was to understand the public's knowledge of nanotechnology in order to identify appropriate starting points for dialog. Survey results showed that people lack true understanding of concepts associated with atoms and the size of the nanoscale regime. Such gaps in understanding lead to a disappointing lack of communication between researchers and the public concerning fundamental concepts in nanoscale science and engineering. Strategies are offered on how scientists should present their research when engaging the public on nanotechnology topics

  11. Nanoscale effects in interdiffusion

    International Nuclear Information System (INIS)

    Erdelyi, Z.; Langer, G.A.; Beke, D.L.; Csik, A.

    2007-01-01

    Complete text of publication follows. Diffusion on the nano/atomic scales in multilayers, thin films has many challenging features even if the role of structural defects can be neglected and 'only' the effects related to the nano/atomic scale raise. The most basic equations to describe the diffusion are Fick's equations. It is important to emphasize that the diffusion coefficient in Fick's equations is in general composition independent and Fick's classical equations do not include the stress effects, which can have important influence onto the diffusion especially on the nano/atomic scale. We illustrate that the continuum descriptions of the diffusion cannot be applied automatically on such short distances, the classical continuum approximations (Fick's laws) cannot describe correctly the atomic movements. They predict faster kinetics than the atomistic models and the interface shift is always proportional to the square root of the time. However, the kinetics can be even linear on the nano/atomic scale. We have shown from computer simulations that Fick's laws violate on the nanoscale either in completely or restricted miscible systems. This is strongly related to the discrete character of the system on the nanoscale and to the highly neglected fact in the literature that the diffusion coefficients depend on the composition. As will be seen the composition dependence of D is very important and has very significant influence on the diffusion kinetics on the nano/atomic scales. It originates from the fact that usually the diffusion coefficients are different in an A and in a B matrix. Consequently in case of a real interface, which is not atomically sharp, i.e. there is a more or less intermixed region between the pure A and B matrixes, the diffusion coefficient changes continuously while e.g. an A atom diffuses from the pure A matrix into the pure B. This feature can be also called diffusion asymmetry. We have also illustrated that in this case not only the

  12. Killer whale morphology - Variation in morphology of killer whale ecotypes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We are using elliptic Fourier analysis to determine the patterns of variation in morphology of dorsal fin shape, saddle patch shape, and eye patch shape of resident,...

  13. Nano-scale processes behind ion-beam cancer therapy

    Science.gov (United States)

    Surdutovich, Eugene; Garcia, Gustavo; Mason, Nigel; Solov'yov, Andrey V.

    2016-04-01

    This topical issue collates a series of papers based on new data reported at the third Nano-IBCT Conference of the COST Action MP1002: Nanoscale Insights into Ion Beam Cancer Therapy, held in Boppard, Germany, from October 27th to October 31st, 2014. The Nano-IBCT COST Action was launched in December 2010 and brought together more than 300 experts from different disciplines (physics, chemistry, biology) with specialists in radiation damage of biological matter from hadron-therapy centres, and medical institutions. This meeting followed the first and the second conferences of the Action held in October 2011 in Caen, France and in May 2013 in Sopot, Poland respectively. This conference series provided a focus for the European research community and has highlighted the pioneering research into the fundamental processes underpinning ion beam cancer therapy. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Gustavo Garcia and Eugene Surdutovich.

  14. Localized temperature and chemical reaction control in nanoscale space by nanowire array.

    Science.gov (United States)

    Jin, C Yan; Li, Zhiyong; Williams, R Stanley; Lee, K-Cheol; Park, Inkyu

    2011-11-09

    We introduce a novel method for chemical reaction control with nanoscale spatial resolution based on localized heating by using a well-aligned nanowire array. Numerical and experimental analysis shows that each individual nanowire could be selectively and rapidly Joule heated for local and ultrafast temperature modulation in nanoscale space (e.g., maximum temperature gradient 2.2 K/nm at the nanowire edge; heating/cooling time chemical reactions such as polymer decomposition/cross-linking and direct and localized hydrothermal synthesis of metal oxide nanowires were demonstrated.

  15. Adhesion and proliferation of OCT-1 osteoblast-like cells on micro- and nano-scale topography structured poly(L-lactide).

    Science.gov (United States)

    Wan, Yuqing; Wang, Yong; Liu, Zhimin; Qu, Xue; Han, Buxing; Bei, Jianzhong; Wang, Shenguo

    2005-07-01

    The impact of the surface topography of polylactone-type polymer on cell adhesion was to be concerned because the micro-scale texture of a surface can provide a significant effect on the adhesion behavior of cells on the surface. Especially for the application of tissue engineering scaffold, the pore size could have an influence on cell in-growth and subsequent proliferation. Micro-fabrication technology was used to generate specific topography to investigate the relationship between the cells and surface. In this study the pits-patterned surfaces of polystyrene (PS) film with diameters 2.2 and 0.45 microm were prepared by phase-separation, and the corresponding scale islands-patterned PLLA surface was prepared by a molding technique using the pits-patterned PS as a template. The adhesion and proliferation behavior of OCT-1 osteoblast-like cells morphology on the pits- and islands-patterned surface were characterized by SEM observation, cell attachment efficiency measurement and MTT assay. The results showed that the cell adhesion could be enhanced on PLLA and PS surface with nano-scale and micro-scale roughness compared to the smooth surfaces of the PLLA and PS. The OCT-1 osteoblast-like cells could grow along the surface with two different size islands of PLLA and grow inside the micro-scale pits of the PS. However, the proliferation of cells on the micro- and nano-scale patterned surface has not been enhanced compared with the controlled smooth surface.

  16. Abstractocyte: A Visual Tool for Exploring Nanoscale Astroglial Cells

    KAUST Repository

    Mohammed, Haneen

    2017-01-01

    This thesis presents the design and implementation of Abstractocyte, a system for the visual analysis of astrocytes, and their relation to neurons, in nanoscale volumes of brain tissue. Astrocytes are glial cells, i.e., non-neuronal cells

  17. Environmental, Health, and Safety Research Needs for Engineered Nanoscale Materials

    National Research Council Canada - National Science Library

    Alderson, Norris; Alexander, Catherine; Merzbacher, Celia; Chernicoff, William; Middendorf, Paul; Beck, Nancy; Chow, Flora; Poster, Dianne; Danello, Mary Ann; Barrera, Enriqueta

    2006-01-01

    ...) research and information needs related to understanding and management of potential risks of engineered nanoscale materials that may be used, for example, in commercial or consumer products, medical...

  18. Quantum Transport Simulations of Nanoscale Materials

    KAUST Repository

    Obodo, Tobechukwu Joshua

    2016-01-07

    Nanoscale materials have many potential advantages because of their quantum confinement, cost and producibility by low-temperature chemical methods. Advancement of theoretical methods as well as the availability of modern high-performance supercomputers allow us to control and exploit their microscopic properties at the atomic scale, hence making it possible to design novel nanoscale molecular devices with interesting features (e.g switches, rectifiers, negative differential conductance, and high magnetoresistance). In this thesis, state-of-the-art theoretical calculations have been performed for the quantum transport properties of nano-structured materials within the framework of Density Functional Theory (DFT) and the Nonequilibrium Green\\'s Function (NEGF) formalism. The switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes is investigated. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond, and thus lowers the conductance. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation. Also examined is current-induced migration of atoms in nanoscale devices that plays an important role for device operation and breakdown. We studied the migration of adatoms and defects in graphene and carbon nanotubes under finite bias. We demonstrate that current-induced forces within DFT are non-conservative, which so far has only been shown for model systems, and can lower migration barrier heights. Further, we investigated the quantum transport behavior of an experimentally observed diblock molecule by varying the amounts of phenyl (donor) and pyrimidinyl (acceptor) rings under finite bias. We show that a tandem configuration of

  19. Electron Microscopy and Analytical X-ray Characterization of Compositional and Nanoscale Structural Changes in Fossil Bone

    Science.gov (United States)

    Boatman, Elizabeth Marie

    The nanoscale structure of compact bone contains several features that are direct indicators of bulk tissue mechanical properties. Fossil bone tissues represent unique opportunities to understand the compact bone structure/property relationships from a deep time perspective, offering a possible array of new insights into bone diseases, biomimicry of composite materials, and basic knowledge of bioapatite composition and nanoscale bone structure. To date, most work with fossil bone has employed microscale techniques and has counter-indicated the survival of bioapatite and other nanoscale structural features. The obvious disconnect between the use of microscale techniques and the discernment of nanoscale structure has prompted this work. The goal of this study was to characterize the nanoscale constituents of fossil compact bone by applying a suite of diffraction, microscopy, and spectrometry techniques, representing the highest levels of spatial and energy resolution available today, and capable of complementary structural and compositional characterization from the micro- to the nanoscale. Fossil dinosaur and crocodile long bone specimens, as well as modern ratite and crocodile femurs, were acquired from the UC Museum of Paleontology. Preserved physiological features of significance were documented with scanning electron microscopy back-scattered imaging. Electron microprobe wavelength-dispersive X-ray spectroscopy (WDS) revealed fossil bone compositions enriched in fluorine with a complementary loss of oxygen. X-ray diffraction analyses demonstrated that all specimens were composed of apatite. Transmission electron microscopy (TEM) imaging revealed preserved nanocrystallinity in the fossil bones and electron diffraction studies further identified these nanocrystallites as apatite. Tomographic analyses of nanoscale elements imaged by TEM and small angle X-ray scattering were performed, with the results of each analysis further indicating that nanoscale structure is

  20. Study of the parameters of nanoscale layers in nanoheterostructures based on II–VI semiconductor compounds

    Energy Technology Data Exchange (ETDEWEB)

    Karavaev, M. B., E-mail: estonianchameleon@gmail.com; Kirilenko, D. A.; Ivanova, E. V.; Popova, T. B.; Sitnikova, A. A.; Sedova, I. V.; Zamoryanskaya, M. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2017-01-15

    Wide-gap ZnSe-based nanoheterostructures grown by molecular-beam epitaxy are studied by local cathodoluminescence and X-ray microanalysis. It is shown that the used methods allow nondestructive determination of the depth, elemental composition, and geometrical parameters of the nanoscale ZnCdSe layer. The accuracy of the results is verified by transmission electron microscopy. The research techniques are based on the possibility of varying the primary electron-beam energy, which results in changes in the regions of characteristic X-ray and cathodoluminescence generation.

  1. Nanoscale structural order from the atomic pair distribution function (PDF): There's plenty of room in the middle

    International Nuclear Information System (INIS)

    Billinge, Simon J.L.

    2008-01-01

    Emerging materials of scientific and technological interest are generally complex and often nanostructured: they have atomic orderings that extend on nanometer length-scales. These can be discrete nanoparticles; bulk crystals with nanoscale chemical or displacive order within them; mesoporous materials that are bulk materials containing nanoscale holes; and nanocomposites that are intimate heterogeneous mixtures of nano-sized constituents. As always, a quantitative knowledge of the atomic structure within these materials is a prerequisite to understanding and engineering their properties. Traditional crystallographic methods for obtaining this information break down at the nanoscale, sometimes referred to as 'the nanostructure problem'. We describe here some emerging methods for studying nanoscale structure. We present some examples of recent successes. Finally, we discuss future directions and opportunities and draw attention to limitations and potential problems. -

  2. Nanoscale inhomogeneity and photoacid generation dynamics in extreme ultraviolet resist materials

    Science.gov (United States)

    Wu, Ping-Jui; Wang, Yu-Fu; Chen, Wei-Chi; Wang, Chien-Wei; Cheng, Joy; Chang, Vencent; Chang, Ching-Yu; Lin, John; Cheng, Yuan-Chung

    2018-03-01

    The development of extreme ultraviolet (EUV) lithography towards the 22 nm node and beyond depends critically on the availability of resist materials that meet stringent control requirements in resolution, line edge roughness, and sensitivity. However, the molecular mechanisms that govern the structure-function relationships in current EUV resist systems are not well understood. In particular, the nanoscale structures of the polymer base and the distributions of photoacid generators (PAGs) should play a critical roles in the performance of a resist system, yet currently available models for photochemical reactions in EUV resist systems are exclusively based on homogeneous bulk models that ignore molecular-level details of solid resist films. In this work, we investigate how microscopic molecular organizations in EUV resist affect photoacid generations in a bottom-up approach that describes structure-dependent electron-transfer dynamics in a solid film model. To this end, molecular dynamics simulations and stimulated annealing are used to obtain structures of a large simulation box containing poly(4-hydroxystyrene) (PHS) base polymers and triphenylsulfonium based PAGs. Our calculations reveal that ion-pair interactions govern the microscopic distributions of the polymer base and PAG molecules, resulting in a highly inhomogeneous system with nonuniform nanoscale chemical domains. Furthermore, the theoretical structures were used in combination of quantum chemical calculations and the Marcus theory to evaluate electron transfer rates between molecular sites, and then kinetic Monte Carlo simulations were carried out to model electron transfer dynamics with molecular structure details taken into consideration. As a result, the portion of thermalized electrons that are absorbed by the PAGs and the nanoscale spatial distribution of generated acids can be estimated. Our data reveal that the nanoscale inhomogeneous distributions of base polymers and PAGs strongly affect the

  3. The Role of Membrane Curvature in Nanoscale Topography-Induced Intracellular Signaling.

    Science.gov (United States)

    Lou, Hsin-Ya; Zhao, Wenting; Zeng, Yongpeng; Cui, Bianxiao

    2018-05-15

    Over the past decade, there has been growing interest in developing biosensors and devices with nanoscale and vertical topography. Vertical nanostructures induce spontaneous cell engulfment, which enhances the cell-probe coupling efficiency and the sensitivity of biosensors. Although local membranes in contact with the nanostructures are found to be fully fluidic for lipid and membrane protein diffusions, cells appear to actively sense and respond to the surface topography presented by vertical nanostructures. For future development of biodevices, it is important to understand how cells interact with these nanostructures and how their presence modulates cellular function and activities. How cells recognize nanoscale surface topography has been an area of active research for two decades before the recent biosensor works. Extensive studies show that surface topographies in the range of tens to hundreds of nanometers can significantly affect cell functions, behaviors, and ultimately the cell fate. For example, titanium implants having rough surfaces are better for osteoblast attachment and host-implant integration than those with smooth surfaces. At the cellular level, nanoscale surface topography has been shown by a large number of studies to modulate cell attachment, activity, and differentiation. However, a mechanistic understanding of how cells interact and respond to nanoscale topographic features is still lacking. In this Account, we focus on some recent studies that support a new mechanism that local membrane curvature induced by nanoscale topography directly acts as a biochemical signal to induce intracellular signaling, which we refer to as the curvature hypothesis. The curvature hypothesis proposes that some intracellular proteins can recognize membrane curvatures of a certain range at the cell-to-material interface. These proteins then recruit and activate downstream components to modulate cell signaling and behavior. We discuss current technologies

  4. Graduated characterization method using a multi-well microplate for reducing reactivity of nanoscale zero valent iron materials

    DEFF Research Database (Denmark)

    Hwang, Yuhoon; Salatas, Apostolos; Mines, Paul D.

    2015-01-01

    Even though nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of n...... with different compounds, combined with the use of a multi-well microplate based color assay, promises to be a useful and simple tool in various nZVI related research topics....

  5. Solvent polarity and nanoscale morphology in bulk heterojunction organic solar cells: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Ajith [Centre for Nano-Bio-Polymer Science and Technology, Department of Physics, St. Thomas College, Pala, Kerala 686574 (India); Research and Development Centre, Bharathiar University, Coimbatore, Tamilnadu 641046 (India); Elsa Tom, Anju; Ison, V. V., E-mail: isonvv@yahoo.in, E-mail: praveen@materials.iisc.ernet.in [Centre for Nano-Bio-Polymer Science and Technology, Department of Physics, St. Thomas College, Pala, Kerala 686574 (India); Rao, Arun D.; Varman, K. Arul; Ranjith, K.; Ramamurthy, Praveen C., E-mail: isonvv@yahoo.in, E-mail: praveen@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science Bangalore, Karnataka 560012 (India); Vinayakan, R. [Department of Chemistry, SVR NSS College Vazhoor, Kerala 686505 (India)

    2014-03-14

    Organic bulk heterojunction solar cells were fabricated under identical experimental conditions, except by varying the solvent polarity used for spin coating the active layer components and their performance was evaluated systematically. Results showed that presence of nitrobenzene-chlorobenzene composition governs the morphology of active layer formed, which is due to the tuning of solvent polarity as well as the resulting solubility of the P3HT:PCBM blend. Trace amount of nitrobenzene favoured the formation of better organised P3HT domains, as evident from conductive AFM, tapping mode AFM and surface, and cross-sectional SEM analysis. The higher interfacial surface area thus generated produced cells with high efficiency. But, an increase in the nitrobenzene composition leads to a decrease in cell performance, which is due to the formation of an active layer with larger size polymer domain networks with poor charge separation possibility.

  6. Solvent polarity and nanoscale morphology in bulk heterojunction organic solar cells: A case study

    International Nuclear Information System (INIS)

    Thomas, Ajith; Elsa Tom, Anju; Ison, V. V.; Rao, Arun D.; Varman, K. Arul; Ranjith, K.; Ramamurthy, Praveen C.; Vinayakan, R.

    2014-01-01

    Organic bulk heterojunction solar cells were fabricated under identical experimental conditions, except by varying the solvent polarity used for spin coating the active layer components and their performance was evaluated systematically. Results showed that presence of nitrobenzene-chlorobenzene composition governs the morphology of active layer formed, which is due to the tuning of solvent polarity as well as the resulting solubility of the P3HT:PCBM blend. Trace amount of nitrobenzene favoured the formation of better organised P3HT domains, as evident from conductive AFM, tapping mode AFM and surface, and cross-sectional SEM analysis. The higher interfacial surface area thus generated produced cells with high efficiency. But, an increase in the nitrobenzene composition leads to a decrease in cell performance, which is due to the formation of an active layer with larger size polymer domain networks with poor charge separation possibility

  7. Evaporation of nanoscale water on a uniformly complete wetting surface at different temperatures.

    Science.gov (United States)

    Guo, Yuwei; Wan, Rongzheng

    2018-05-03

    The evaporation of nanoscale water films on surfaces affects many processes in nature and industry. Using molecular dynamics (MD) simulations, we show the evaporation of a nanoscale water film on a uniformly complete wetting surface at different temperatures. With the increase in temperature, the growth of the water evaporation rate becomes slow. Analyses show that the hydrogen bond (H-bond) lifetimes and orientational autocorrelation times of the outermost water film decrease slowly with the increase in temperature. Compared to a thicker water film, the H-bond lifetimes and orientational autocorrelation times of a monolayer water film are much slower. This suggests that the lower evaporation rate of the monolayer water film on a uniformly complete wetting surface may be caused by the constriction of the water rotation due to the substrate. This finding may be helpful for controlling nanoscale water evaporation within a certain range of temperatures.

  8. Eruptive viscosity and volcano morphology

    International Nuclear Information System (INIS)

    Posin, S.B.; Greeley, R.

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology

  9. Fracture toughness of a nanoscale WC-Co tool steel

    International Nuclear Information System (INIS)

    Densley, J.M.; Hirth, J.P.

    1997-01-01

    Tungsten carbide tool steels, comprising WC particles with 6.7--25wt% Co distributed in the interparticle regions as a quasi-continuous binder phase, can be considered as WC-Co composites. The fracture toughness of such WC-Co composites is dependent on the volume fraction, contiguity and thickness of the cobalt binder, and the size of the tungsten carbide grains. Research has shown that the ductile binder undergoes nearly all the plastic deformation during fracture, which provides the primary energy consuming process that enhances fracture resistance. Recent manufacturing developments have given rise to the production of a WC-6.7wt% Co cermet having an average WC grain size of 70 nm, with a corresponding binder mean thickness, h, of 9 nm calculated from d = h(1-V f )/V f where d = 70 nm and V f = 0.114. This composite has shown a higher wear resistance than that of conventional cermets in proportion to their hardness. Such improvement has been attributed to the difficulty in forming dislocations in the very small grains. There are also indications that the Co binder in the nanoscale cermet contains higher contents of dissolved W and C than for conventional scale cermets. Because plastic deformation is initially confined to the binder phase, it was of interest to perform mode 1 and mixed mode toughness tests on the nanoscale cermet to determine whether flow localization influenced mixed mode toughness as in bulk materials. Two generations of this cermet were provided by Rogers Tool Works. The first generation, A, had lower binder contiguity, with occasional agglomerations of WC grains. The second generation, B, was cleaner, with the cobalt binder more uniformly separating the WC grains

  10. Photoresponsive Bridged Silsesquioxane Nanoparticles with Tunable Morphology for Light-Triggered Plasmid DNA Delivery

    KAUST Repository

    Fatieiev, Yevhen

    2015-09-25

    Bridged silsesquioxane nanocomposites with tunable morphologies incorporating o-nitrophenylene-ammonium bridges are described. The systematic screening of the sol-gel parameters allowed the material to reach the nanoscale –unlike most reported bridged silsesquioxane materials– with controlled dense and hollow structures of 100 to 200 nm. The hybrid composition of silsesquioxanes with 50% of organic content homogenously distributed in the nanomaterials endowed them with photoresponsive properties. Light irradiation was performed to reverse the surface charge of nanoparticles from +46 to -39 mV via the photoreaction of the organic fragments within the particles, as confirmed by spectroscopic monitorings. Furthermore, such NPs were ap-plied for the first time for the on-demand delivery of plasmid DNA in HeLa cancer cells via light actuation.

  11. Photoresponsive Bridged Silsesquioxane Nanoparticles with Tunable Morphology for Light-Triggered Plasmid DNA Delivery

    KAUST Repository

    Fatieiev, Yevhen; Croissant, Jonas G.; Alsaiari, Shahad K.; Moosa, Basem; Anjum, Dalaver H.; Khashab, Niveen M.

    2015-01-01

    Bridged silsesquioxane nanocomposites with tunable morphologies incorporating o-nitrophenylene-ammonium bridges are described. The systematic screening of the sol-gel parameters allowed the material to reach the nanoscale –unlike most reported bridged silsesquioxane materials– with controlled dense and hollow structures of 100 to 200 nm. The hybrid composition of silsesquioxanes with 50% of organic content homogenously distributed in the nanomaterials endowed them with photoresponsive properties. Light irradiation was performed to reverse the surface charge of nanoparticles from +46 to -39 mV via the photoreaction of the organic fragments within the particles, as confirmed by spectroscopic monitorings. Furthermore, such NPs were ap-plied for the first time for the on-demand delivery of plasmid DNA in HeLa cancer cells via light actuation.

  12. Nanoscale Science and Engineering in Romania

    International Nuclear Information System (INIS)

    Dascalu, Dan; Topa, Vladimir; Kleps, Irina

    2001-01-01

    In spite of difficult working conditions and with very low financial support, many groups from Romania are involved in emerging fields, such as the nanoscale science and technology. Until the last years, this activity was developed without a central coordination and without many interactions between these research groups. In the year 2000, some of the institutes and universities active in the nanotechnology field in Romania founded the MICRONANOTECH network. The aim of this paper is to emphasize the main activities and results of the Romanian groups working in this novel domain. Most of the groups are deal with the nanomaterial technology and only few of them have activities in nanostructure science and engineering, in new concepts and device modeling and technology. This paper describes the nanotechnology research development in two of the most significant institutes from Romania: Centre for Nanotechnologies from National Institute for Research and Development in Microtehnologies (IMT-Bucharest) and from National Institute for Research and Development in Materials Physics (INCD-FM), Magurele. The Romanian research results in nanotechnology field were presented in numerous papers presented in international conferences or published in national and international journals. They are also presented in patents, international awards and fellowships. The research effort and financial support are outlined. Some future trends of the Romanian nanoscale science and technology research are also described

  13. Computer simulations for the nano-scale

    International Nuclear Information System (INIS)

    Stich, I.

    2007-01-01

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

  14. Examination of High Resolution Channel Topography to Determine Suitable Metrics to Characterize Morphological Complexity

    Science.gov (United States)

    Stewart, R. L.; Gaeuman, D.

    2015-12-01

    Complex bed morphology is deemed necessary to restore salmonid habitats, yet quantifiable metrics that capture channel complexity have remained elusive. This work utilizes high resolution topographic data from the 40 miles of the Trinity River of northern California to determine a suitable metric for characterizing morphological complexity at the reach scale. The study area is segregated into reaches defined by individual riffle pool units or aggregates of several consecutive units. Potential measures of complexity include rugosity and depth statistics such as standard deviation and interquartile range, yet previous research has shown these metrics are scale dependent and subject to sampling density-based bias. The effect of sampling density on the present analysis has been reduced by underrepresenting the high resolution topographic data as a 3'x 3' raster so that all areas are equally sampled. Standard rugosity, defined as the three-dimensional surface area divided by projected area, has been shown to be dependent on average depth. We therefore define R*, a empirically depth-corrected rugosity metric in which rugosity is corrected using an empirical relationship based on linear regression between the standard rugosity metric and average depth. By removing the dependence on depth using a regression based on the study reach, R* provides a measure reach scale complexity relative to the entire study area. The interquartile range of depths is also depth-dependent, so we defined a non-dimensional metric (IQR*) as the interquartile range dividing by median depth. These are calculated to develop rankings of channel complexity which, are found to closely agree with perceived channel complexity observed in the field. Current efforts combine these measures of morphological complexity with salmonid habitat suitability to evaluate the effects of channel complexity on the various life stages of salmonids. Future work will investigate the downstream sequencing of channel

  15. Nanoscale indent formation in shape memory polymers using a heated probe tip

    Energy Technology Data Exchange (ETDEWEB)

    Yang, F [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801 (United States); Wornyo, E [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Gall, K [Department of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); King, W P [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801 (United States)

    2007-07-18

    This paper presents experimental investigation of nanoscale indentation formation in shape memory polymers. The polymers were synthesized by photopolymerizing a tert-butyl acrylate (tBA) monomer with a poly(ethylene glycol dimethacrylate) (PEGDMA) crosslinker. The concentration and the molecular weight of the crosslinker were varied to produce five polymers with tailored properties. Nanoscale indentations were formed on the polymer surfaces by using a heated atomic force microscope (AFM) cantilever at various temperatures near or above the glass transition (between 84 and 215 deg. C) and a range of heating durations from 100 {mu}s to 8 ms. The images of the indents were obtained with the same probe tip at room temperature. The contact pressure, a measure of transient hardness, was derived from the indentation height data as a function of time and temperature for different polymers. With increasing crosslinker molecular weight and decreasing crosslinker concentration, the contact pressures decreased at a fixed maximum load due to increased crosslink spacing in the polymer system. The results provide insight into the nanoscale response of these novel materials.

  16. A novel nanoscale-dispersed eye ointment for the treatment of dry eye disease

    Science.gov (United States)

    Zhang, Wenjian; Wang, Yan; Lee, Benjamin Tak Kwong; Liu, Chang; Wei, Gang; Lu, Weiyue

    2014-03-01

    A novel nanoscale-dispersed eye ointment (NDEO) for the treatment of severe evaporative dry eye has been successfully developed. The excipients used as semisolid lipids were petrolatum and lanolin, as used in conventional eye ointment, which were coupled with medium-chain triglycerides (MCT) as a liquid lipid; both phases were then dispersed in polyvinyl pyrrolidone solution to form a nanodispersion. Single-factor experiments were conducted to optimize the formulations. A transmission electron micrograph showed that the ointment matrix was entrapped in the nanoemulsion of MCT, with a mean particle size of about 100 nm. The optimized formulation of NDEO was stable when stored for six months at 4 °C, and demonstrated no cytotoxicity to human corneal epithelial cells when compared with commercial polymer-based artificial tears (Tears Natural® Forte). The therapeutic effects of NDEO were evaluated on a mouse model with ‘dry eye’. Both the tear break-up time and fluorescein staining demonstrated therapeutic improvement, displaying a trend of positive correlation with higher concentrations of ointment matrix in the NDEO formulations compared to a marketed product. Histological evaluation demonstrated that the NDEO restored the normal corneal and conjunctival morphology and is safe for ophthalmic application.

  17. Nanoscale “Quantum” Islands on Metal Substrates: Microscopy Studies and Electronic Structure Analyses

    Directory of Open Access Journals (Sweden)

    Da-Jiang Liu

    2010-07-01

    Full Text Available Confinement of electrons can occur in metal islands or in continuous films grown heteroepitaxially upon a substrate of a different metal or on a metallic alloy. Associated quantum size effects (QSE can produce a significant height-dependence of the surface free energy for nanoscale thicknesses of up to 10–20 layers. This may suffice to induce height selection during film growth. Scanning STM analysis has revealed remarkable flat-topped or mesa-like island and film morphologies in various systems. We discuss in detail observations of QSE and associated film growth behavior for Pb/Cu(111, Ag/Fe(100, and Cu/fcc-Fe/Cu(100 [A/B or A/B/A], and for Ag/NiAl(110 with brief comments offered for Fe/Cu3Au(001 [A/BC binary alloys]. We also describe these issues for Ag/5-fold i-Al-Pd-Mn and Bi/5-fold i-Al-Cu-Fe [A/BCD ternary icosohedral quasicrystals]. Electronic structure theory analysis, either at the level of simple free electron gas models or more sophisticated Density Functional Theory calculations, can provide insight into the QSE-mediated thermodynamic driving force underlying height selection.

  18. Nanomaterial Case Studies: Nanoscale Titanium Dioxide (External Review Draft)

    Science.gov (United States)

    This draft document presents two case studies of nanoscale titanium dioxide (nano-TiO2) used (1) to remove arsenic from drinking water and (2) as an active ingredient in topical sunscreen. The draft case studies are organized around a comprehensive environmental asses...

  19. Dwell time dependent morphological transition and sputtering yield of ion sputtered Sn

    International Nuclear Information System (INIS)

    Qian, H X; Zeng, X R; Zhou, W

    2010-01-01

    Self-organized nano-scale patterns may appear on a wide variety of materials irradiated with an ion beam. Good manipulation of these structures is important for application in nanostructure fabrication. In this paper, dwell time has been demonstrated to be able to control the ripple formation and sputtering yield on Sn surface. Ripples with a wavelength of 1.7 μm were observed for a dwell time in the range 3-20 μs, whereas much finer ripples with a wavelength of 540 nm and a different orientation were observed for a shorter dwell time in the range 0.1-2 μs. The sputtering yield increases with dwell time significantly. The results provide a new basis for further steps in the theoretical description of morphology evolution during ion beam sputtering.

  20. Micro- and nanoscale phenomena in tribology

    CERN Document Server

    Chung, Yip-Wah

    2011-01-01

    Drawn from presentations at a recent National Science Foundation Summer Institute on Nanomechanics, Nanomaterials, and Micro/Nanomanufacturing, Micro- and Nanoscale Phenomena in Tribology explores the convergence of the multiple science and engineering disciplines involved in tribology and the connection from the macro to nano world. Written by specialists from computation, materials science, mechanical engineering, surface physics, and chemistry, each chapter provides up-to-date coverage of both basic and advanced topics and includes extensive references for further study.After discussing the

  1. Infochemistry Information Processing at the Nanoscale

    CERN Document Server

    Szacilowski, Konrad

    2012-01-01

    Infochemistry: Information Processing at the Nanoscale, defines a new field of science, and describes the processes, systems and devices at the interface between chemistry and information sciences. The book is devoted to the application of molecular species and nanostructures to advanced information processing. It includes the design and synthesis of suitable materials and nanostructures, their characterization, and finally applications of molecular species and nanostructures for information storage and processing purposes. Divided into twelve chapters; the first three chapters serve as an int

  2. Highly repeatable nanoscale phase coexistence in vanadium dioxide films

    Science.gov (United States)

    Huffman, T. J.; Lahneman, D. J.; Wang, S. L.; Slusar, T.; Kim, Bong-Jun; Kim, Hyun-Tak; Qazilbash, M. M.

    2018-02-01

    It is generally believed that in first-order phase transitions in materials with imperfections, the formation of phase domains must be affected to some extent by stochastic (probabilistic) processes. The stochasticity would lead to unreliable performance in nanoscale devices that have the potential to exploit the transformation of physical properties in a phase transition. Here we show that stochasticity at nanometer length scales is completely suppressed in the thermally driven metal-insulator transition (MIT) in sputtered vanadium dioxide (V O2 ) films. The nucleation and growth of domain patterns of metallic and insulating phases occur in a strikingly reproducible way. The completely deterministic nature of domain formation and growth in films with imperfections is a fundamental and unexpected finding about the kinetics of this material. Moreover, it opens the door for realizing reliable nanoscale devices based on the MIT in V O2 and similar phase-change materials.

  3. Doping dependence of electrical and thermal conductivity of nanoscale polyaniline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin Jiezhu; Wang Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Haque, M A [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-26

    We performed simultaneous characterization of electrical and thermal conductivity of 55 nm thick polyaniline (PANI) thin films doped with different levels of camphor sulfonic acids (CSAs). The effect of the doping level is more pronounced on electrical conductivity than on thermal conductivity of PANIs, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% (the molar ratio of CSA to phenyl-N repeat unit of PANI) doping level, PANI exhibited the maximum electrical and thermal conductivity due to the formation of mostly delocalized structures. Whereas polarons are the charge carriers responsible for the electrical conduction, phonons are believed to play a dominant role in the heat conduction in nanoscale doped PANI thin films.

  4. Quantitative FLIM-FRET Microscopy to Monitor Nanoscale Chromatin Compaction In Vivo Reveals Structural Roles of Condensin Complexes

    Directory of Open Access Journals (Sweden)

    David Llères

    2017-02-01

    Full Text Available How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer-based fluorescence lifetime imaging microscopy (FLIM approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells. Using RNAi and repetitive extrachromosomal array approaches, we defined the heterochromatin state and showed that its architecture presents a nanoscale-compacted organization controlled by Heterochromatin Protein-1 (HP1 and SETDB1 H3-lysine-9 methyltransferase homologs in vivo. Next, we functionally explored condensin complexes. We found that condensin I and condensin II are essential for heterochromatin compaction and that condensin I additionally controls lowly compacted regions. Our data show that, in living animals, nanoscale chromatin compaction is controlled not only by histone modifiers and readers but also by condensin complexes.

  5. How fast are the ultra-fast nano-scale solid-liquid phase transitions induced by energetic particles in solids?

    International Nuclear Information System (INIS)

    Lopasso, E.M.; Caro, A.; Caro, M.

    2003-01-01

    We study the thermodynamic forces acting on the evolution of the nanoscale regions excited by collisions of energetic particles into solid targets. We analyze the role of diffusion, thermo-migration, and the liquidus-solidus two-phase field crossing, as the system cools down from the collision-induced melt under different conditions of energy deposition. To determine the relevance of these thermodynamic forces, solute redistribution is evaluated using molecular dynamics simulations of equilibrium Au-Ni solid solutions. At low collision energies, our results show that the quenching of spherical cascades is too fast to allow for solute redistribution according to equilibrium solidification as determined from the equilibrium phase diagram (zone refining effect), and only thermo-migration is observed. At higher energies instead, in the cylindrical symmetry of ion tracks, quenching rate is in a range that shows the combined effects of thermo-migration and solute redistribution that, depending on the material, can reinforce or cancel each other. These results are relevant for the interpretation of the early stage of radiation damage in alloys, and show that the combination of ultra-fast but nano-scale characteristics of these processes can still be described in terms of linear response of the perturbed system

  6. Nanoscale structure and atomic disorder in the iron-based chalcogenides

    Directory of Open Access Journals (Sweden)

    Naurang Lal Saini

    2013-01-01

    Full Text Available The multiband iron-based superconductors have layered structure with a phase diagram characterized by a complex interplay of charge, spin and lattice excitations, with nanoscale atomic structure playing a key role in their fundamental electronic properties. In this paper, we briefly review nanoscale structure and atomic disorder in iron-based chalcogenide superconductors. We focus on the Fe(Se,S1−xTex (11-type and K0.8Fe1.6Se2 (122-type systems, discussing their local structure obtained by extended x-ray absorption fine structure. Local structure studies on the Fe(Se,S1−xTex system reveal clear nanoscale phase separation characterized by coexisting components of different atomic configurations, similar to the case of random alloys. In fact, the Fe–Se/S and Fe–Te distances in the ternary Fe(Se,S1−xTex are found to be closer to the respective distances in the binary FeSe/FeS and FeTe systems, showing significant divergence of the local structure from the average one. The observed features are characteristic of ternary random alloys, indicating breaking of the local symmetry in these materials. On the other hand, K0.8Fe1.6Se2 is known for phase separation in an iron-vacancy ordered phase and an in-plane compressed lattice phase. The local structure of these 122-type chalcogenides shows that this system is characterized by a large local disorder. Indeed, the experiments suggest a nanoscale glassy phase in K0.8Fe1.6Se2, with the superconductivity being similar to the granular materials. While the 11-type structure has no spacer layer, the 122-type structure contains intercalated atoms unlike the 1111-type REFeAsO (RE = rare earth oxypnictides, having well-defined REO spacer layers. It is clear that the interlayer atomic correlations in these iron-based superconducting structures play an important role in structural stability as well as superconductivity and magnetism.

  7. Displacement measurement with nanoscale resolution using a coded micro-mark and digital image correlation

    Science.gov (United States)

    Huang, Wei; Ma, Chengfu; Chen, Yuhang

    2014-12-01

    A method for simple and reliable displacement measurement with nanoscale resolution is proposed. The measurement is realized by combining a common optical microscopy imaging of a specially coded nonperiodic microstructure, namely two-dimensional zero-reference mark (2-D ZRM), and subsequent correlation analysis of the obtained image sequence. The autocorrelation peak contrast of the ZRM code is maximized with well-developed artificial intelligence algorithms, which enables robust and accurate displacement determination. To improve the resolution, subpixel image correlation analysis is employed. Finally, we experimentally demonstrate the quasi-static and dynamic displacement characterization ability of a micro 2-D ZRM.

  8. Nanoscale nuclear architecture for cancer diagnosis by spatial-domain low-coherence quantitative phase microscopy

    Science.gov (United States)

    Wang, Pin; Bista, Rajan K.; Khalbuss, Walid E.; Qiu, Wei; Staton, Kevin D.; Zhang, Lin; Brentnall, Teresa A.; Brand, Randall E.; Liu, Yang

    2011-03-01

    Alterations in nuclear architecture are the hallmark diagnostic characteristic of cancer cells. In this work, we show that the nuclear architectural characteristics quantified by spatial-domain low-coherence quantitative phase microscopy (SL-QPM), is more sensitive for the identification of cancer cells than conventional cytopathology. We demonstrated the importance of nuclear architectural characteristics in both an animal model of intestinal carcinogenesis - APC/Min mouse model and human cytology specimens with colorectal cancer by identifying cancer from cytologically noncancerous appearing cells. The determination of nanoscale nuclear architecture using this simple and practical optical instrument is a significant advance towards cancer diagnosis.

  9. Real time macrophage migration analysis and associated pro-inflammatory cytokine release on transparent carbon nanotube/polymer composite nano-film

    International Nuclear Information System (INIS)

    Khang, Dongwoo

    2015-01-01

    Surface chemistry and nanoscale surface morphology are both influential factors for cell adhesion, growth, and differentiation. In particular, cell migration is one of the major markers of initial immune response activation to implanted biomaterials. Despite their indication, it has been difficult to directly examine macrophages on nanoscale materials, because most nanomaterials possess greater thicknesses than nanoscale. This study developed transparent films comprising a carbon nanotube and polymer composite with controlled surface stiffness and nanoscale roughness. As nanoscale surface topography can incite immune cell activation, analysis of the real-time cell migration (including velocity) of macrophages due to changes in nanoscale surface topography of a biopolymer can support the direct relationship between initial macrophage dynamics and corresponding pro-inflammatory responses. Through real-time analysis, we have identified that surface chemistry and surface nanoscale topography are both independent factors mediating macrophage interactions, and, thus, immune cell behavior can be further controlled by the systematic variation of nanoscale surface topography for a given surface chemistry. Considering that the initial immune response can determine the fate and lifetime of implanted biomaterials, this study presents the direct relationship between initial macrophage dynamics and subsequent inflammatory cytokine release on transparent carbon nanotube polymer composites. (paper)

  10. Modeling of nanoscale liquid mixture transport by density functional hydrodynamics

    Science.gov (United States)

    Dinariev, Oleg Yu.; Evseev, Nikolay V.

    2017-06-01

    Modeling of multiphase compositional hydrodynamics at nanoscale is performed by means of density functional hydrodynamics (DFH). DFH is the method based on density functional theory and continuum mechanics. This method has been developed by the authors over 20 years and used for modeling in various multiphase hydrodynamic applications. In this paper, DFH was further extended to encompass phenomena inherent in liquids at nanoscale. The new DFH extension is based on the introduction of external potentials for chemical components. These potentials are localized in the vicinity of solid surfaces and take account of the van der Waals forces. A set of numerical examples, including disjoining pressure, film precursors, anomalous rheology, liquid in contact with heterogeneous surface, capillary condensation, and forward and reverse osmosis, is presented to demonstrate modeling capabilities.

  11. Charge transport in nanoscale vertical organic semiconductor pillar devices

    NARCIS (Netherlands)

    Wilbers, J.G.E.; Xu, B.; Bobbert, P.A.; de Jong, M.P.; van der Wiel, W.G.

    2017-01-01

    We report charge transport measurements in nanoscale vertical pillar structures incorporating ultrathin layers of the organic semiconductor poly(3-hexylthiophene) (P3HT). P3HT layers with thickness down to 5 nm are gently top-contacted using wedging transfer, yielding highly reproducible, robust

  12. DOE - BES Nanoscale Science Research Centers (NSRCs)

    Energy Technology Data Exchange (ETDEWEB)

    Beecher, Cathy Jo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-14

    These are slides from a powerpoint shown to guests during tours of Center for Integrated Nanotechnologies (CINT) at Los Alamos National Laboratory. It shows the five DOE-BES nanoscale science research centers (NSRCs), which are located at different national laboratories throughout the country. Then it goes into detail specifically about the Center for Integrated Nanotechnologies at LANL, including statistics on its user community and CINT's New Mexico industrial users.

  13. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Fei, E-mail: paper_mail@126.com [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Baochun; Cai, Jing [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Jiang, Yaodong [Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Xu, Jun [Department of Health Economy Administration, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Wang, Shan [Department of Pharmacy, Winthrop University Hospital, Mineola, NY 11501 (United States)

    2014-04-01

    Highlights: • Metal-organic frameworks (MOFs) represent a newborn family of hybrid materials. • MOFs have already shown promise in a number of biological applications. • The biological applications of MOFs raise concerns for potential cytotoxicity. • Substantial information about MOF's neurotoxicity is still quite scarce. • This study reveals for the first time the interaction of MOFs with neural cells. - Abstract: Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn{sup 2+} into the cytosol to cause increased intracellular concentration of Zn{sup 2+}. We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application.

  14. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

    International Nuclear Information System (INIS)

    Ren, Fei; Yang, Baochun; Cai, Jing; Jiang, Yaodong; Xu, Jun; Wang, Shan

    2014-01-01

    Highlights: • Metal-organic frameworks (MOFs) represent a newborn family of hybrid materials. • MOFs have already shown promise in a number of biological applications. • The biological applications of MOFs raise concerns for potential cytotoxicity. • Substantial information about MOF's neurotoxicity is still quite scarce. • This study reveals for the first time the interaction of MOFs with neural cells. - Abstract: Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn 2+ into the cytosol to cause increased intracellular concentration of Zn 2+ . We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application

  15. Characterization of NiSi nanowires as field emitters and limitations of Fowler-Nordheim model at the nanoscale

    Science.gov (United States)

    Belkadi, Amina B.; Gale, E.; Isakovic, A. F.

    2015-03-01

    Nanoscale field emitters are of technological interest because of the anticipated faster turn-on time, better sustainability and compactness. This report focuses on NiSi nanowires as field emitters for two reasons: (a) possible enhancement of field emission in nanoscale field emitters over bulk, and (b) achieving the same field emission properties as in bulk, but at a lower energy cost. To this end, we have grown, fabricated and characterized NiSi nanowires as field emitters. Depending on the geometry of the NiSi nanowires (aspect ratio, shape etc.), the relevant major field emission parameters, such as (1) the turn-on field, (2) the work function, and (3) the field enhancement factor, can be comparable or even superior to other recently explored nanoscale field emitters, such as CdS and ZnO. We also report on a comparative performance of various nanoscale field emitters and on the difficulties in the performance comparison in the light of relatively poor applicability of the standard Folwer-Nordheim model for field emission analysis for the case of the nanoscale field emitters. Proposed modifications are discussed. This work is supported through SRC-ATIC Grant 2011-KJ-2190. We also acknoweldge BNL-CFN and Cornell CNF facilities and staff.

  16. The Effect of Rotating Collector Design on Tensile Properties and Morphology of Electrospun Polycaprolactone Fibres

    Directory of Open Access Journals (Sweden)

    Anindyajati Adhi

    2015-01-01

    Full Text Available Electrospinning is a technique that can produce fibres in the nanoscale range. This process is useful for many applications, including fabrication of fibrous scaffolds for fibrocartilage tissue engineering. For this application, cell attachment and tissue development is influenced by fibre morphology and mechanical properties. This electrospinning study investigated the influence of rotating collector design on morphology and mechanical properties of electrospun polycaprolactone fibre. The experiment employed 4 mandrel designs: 1 full surface of aluminium; 2 with gap feature; 3 with gap feature and teflon support; 4 with gap feature and tape support. The highest elastic modulus was obtained from mandrel with gap and tape support, which was 24.6 MPa and significantly higher compared to fibres acquired from other collector designs. Fibre diameter attained was identical across the different collectors, ranging from 0.5 - 2 μm. Gap introduction showed enhanced alignment in the resultant fibre. It can be concluded that fibre alignment and tensile properties can be improved by simply modifying the collector design. This improved fibre mat can be developed as a biomaterial for fibrocartilage tissue engineering scaffolds.

  17. Nanoscale and submicron fatigue crack growth in nickel microbeams

    International Nuclear Information System (INIS)

    Yang, Y.; Yao, N.; Imasogie, B.; Soboyejo, W.O.

    2007-01-01

    This paper presents a novel edge-notched microbeam technique for the study of short fatigue crack growth. The technique is used to study submicron and nanoscale fatigue in LIGA Ni thin films with columnar microstructures. The edge-notched microbeams were fabricated within LIGA Ni thin films, using focused ion beam (FIB) techniques. The microbeams were then cyclically deformed to failure at a stress ratio of 0.1. Different slip-band structures were observed below the nanoscale notches. Cyclic deformation resulted in the formation of primary slip bands below the notch. Subsequent crack growth then occurred by the unzipping of fatigue cracks along intersecting slip bands. The effects of the primary slip bands were idealized using dislocation-based models. These were used to estimate the intrinsic fatigue threshold and the fatigue endurance limit. The estimates from the model are shown to be consistent with experimental data from prior stress-life experiments and current/prior fatigue threshold estimates

  18. Magnetization switching schemes for nanoscale three-terminal spintronics devices

    Science.gov (United States)

    Fukami, Shunsuke; Ohno, Hideo

    2017-08-01

    Utilizing spintronics-based nonvolatile memories in integrated circuits offers a promising approach to realize ultralow-power and high-performance electronics. While two-terminal devices with spin-transfer torque switching have been extensively developed nowadays, there has been a growing interest in devices with a three-terminal structure. Of primary importance for applications is the efficient manipulation of magnetization, corresponding to information writing, in nanoscale devices. Here we review the studies of current-induced domain wall motion and spin-orbit torque-induced switching, which can be applied to the write operation of nanoscale three-terminal spintronics devices. For domain wall motion, the size dependence of device properties down to less than 20 nm will be shown and the underlying mechanism behind the results will be discussed. For spin-orbit torque-induced switching, factors governing the threshold current density and strategies to reduce it will be discussed. A proof-of-concept demonstration of artificial intelligence using an analog spin-orbit torque device will also be reviewed.

  19. Nanoscale waveguiding methods

    Directory of Open Access Journals (Sweden)

    Wang Chia-Jean

    2007-01-01

    Full Text Available AbstractWhile 32 nm lithography technology is on the horizon for integrated circuit (IC fabrication, matching the pace for miniaturization with optics has been hampered by the diffraction limit. However, development of nanoscale components and guiding methods is burgeoning through advances in fabrication techniques and materials processing. As waveguiding presents the fundamental issue and cornerstone for ultra-high density photonic ICs, we examine the current state of methods in the field. Namely, plasmonic, metal slot and negative dielectric based waveguides as well as a few sub-micrometer techniques such as nanoribbons, high-index contrast and photonic crystals waveguides are investigated in terms of construction, transmission, and limitations. Furthermore, we discuss in detail quantum dot (QD arrays as a gain-enabled and flexible means to transmit energy through straight paths and sharp bends. Modeling, fabrication and test results are provided and show that the QD waveguide may be effective as an alternate means to transfer light on sub-diffraction dimensions.

  20. EDITORIAL: Physical behaviour at the nanoscale: a model for fertile research Physical behaviour at the nanoscale: a model for fertile research

    Science.gov (United States)

    Demming, Anna

    2013-06-01

    At the nanoscale physics follows familiar principles that lead to unfamiliar and even unlikely responses. The change in the balance of a range of physical features results in behaviour that can differ wildly from the same materials at the macroscale. In this issue Di Ventra and Pershin examine some of the memory effects that have attracted increasing interest in investigations of nanoscale electronic systems [1]. The work builds on the familiar premise that external perturbations cannot have an instantaneous effect on any condensed matter system. As they point out, 'This is even more so in systems of nanoscale dimensions where the dynamics of a few atoms may affect the whole structure dramatically'. In this way they explain that the response of these systems will always have some degree of memory present and that memristive, memcapacitive and meminductive systems are simply examples where this feature is particularly prominent. In the late 1990s investigations into the use of carbon nanotubes and SiC nanorods revealed that the moduli of these structures changes with diameter, highlighting the eccentricities of mechanical properties at the nanoscale. These results prompted Miller at the University of Saskatchewan and Shenoy at the Indian Institute of Technology to study the properties of nanotubes and nanorods in detail [2]. 'In the eyes of an engineer these structures are essentially little beams', they explained, 'Albeit they are "little" to a degree that challenges our traditional notions of continuum mechanics'. In their work they developed one of the first simple models for explaining the behaviour of the Young's modulus of nanostructures, verified by direct atomistic simulation of axial loading of these structures. Since then, consideration of different nanoscale structures and the dissipation of energy under stress and strain have also demystified the extraordinary mechanical properties of natural materials such as collagen [3] and spider's silk [4]. The

  1. Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces

    Science.gov (United States)

    Ochoa, Rosie; Davis, Brian; Conley, Hiram; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

    2008-10-01

    Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM.

  2. Feasibility Study of Nanoscale Semiconductor Manufacture Using Thermal Dip Pen Nanolithography

    National Research Council Canada - National Science Library

    King, William P

    2006-01-01

    ...) for the purpose of nanoscale electronics manufacturing. In this project, we have demonstrated that using the thermal DPN technique that both indium metal, and semiconducting organic materials (PDDT, PVDF...

  3. Nanoscale and Microscale Heat Transfer V (NMHT-V) EUROTHERM seminar No 108

    International Nuclear Information System (INIS)

    Termentzidis, Konstantinos; Lacroix, David; Zianni, Xanthippi

    2017-01-01

    This special volume of JPCS contains the Proceedings of the 5 th Nanoscale and Microscale Heat Transfer (NMHT-V). The conference was held in Santorini, Greece, from September 26 th to September 30 th 2016. The NMHT Eurotherm seminar series aim to give the state-of-the-art and to present the most recent advances of the scientific research in the field of heat transfer at nanoscale and microscale where classical macroscopic heat transfer laws might be not applicable. NMHT-V is the 5 th of the Eurotherm seminars. Previous seminars were held in Lyon (October 2014), Poitiers (1998 and 2011) and Reims (2003). NMHT-V had more than 100 participants, among them 30 PhD students, mainly from Europe (England, France, Germany, Spain, Italy, Greece, Ukraine, Finland, Russia…15 countries) but also from countries outside Europe (U.S., Japan etc). Universities and research laboratories doing pioneering work in the scientific field of the seminar were represented. During the 5 days of the conference (26-30 September 2016), scientists and researchers presented and discussed their most recent advances through more than 75 talks during 17 sessions. Furthermore, a poster session with 30 presentations had allowed fruitful exchanges between. A Special Flash poster presentation session (2 minutes for each poster) was included on the first day of the conference to give the opportunity to the researchers/students to introduce their work to the audience. The scientific program included keynote lectures and tutorials. Moreover, the annual one-day (September 28 th ) workshop of the European research project 'Quantiheat': http://www.quantiheat.eu/ was hosted on the conference location and was open to all participants interested in quantitative measurements at micro/nanoscale and thermal imaging. The conference organisers gratefully acknowledge the members of the scientific committee and the experts who carried out the reviews of abstracts and of proceeding articles. Also acknowledged

  4. A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure.

    Science.gov (United States)

    Sun, Xiaoxia; Uyama, Hiroshi

    2013-10-04

    A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields.

  5. Nanoscale Science, Engineering and Technology Research Directions

    Energy Technology Data Exchange (ETDEWEB)

    Lowndes, D. H.; Alivisatos, A. P.; Alper, M.; Averback, R. S.; Jacob Barhen, J.; Eastman, J. A.; Imre, D.; Lowndes, D. H.; McNulty, I.; Michalske, T. A.; Ho, K-M; Nozik, A. J.; Russell, T. P.; Valentin, R. A.; Welch, D. O.; Barhen, J.; Agnew, S. R.; Bellon, P.; Blair, J.; Boatner, L. A.; Braiman, Y.; Budai, J. D.; Crabtree, G. W.; Feldman, L. C.; Flynn, C. P.; Geohegan, D. B.; George, E. P.; Greenbaum, E.; Grigoropoulos, C.; Haynes, T. E.; Heberlein, J.; Hichman, J.; Holland, O. W.; Honda, S.; Horton, J. A.; Hu, M. Z.-C.; Jesson, D. E.; Joy, D. C.; Krauss, A.; Kwok, W.-K.; Larson, B. C.; Larson, D. J.; Likharev, K.; Liu, C. T.; Majumdar, A.; Maziasz, P. J.; Meldrum, A.; Miller, J. C.; Modine, F. A.; Pennycook, S. J.; Pharr, G. M.; Phillpot, S.; Price, D. L.; Protopopescu, V.; Poker, D. B.; Pui, D.; Ramsey, J. M.; Rao, N.; Reichl, L.; Roberto, J.; Saboungi, M-L; Simpson, M.; Strieffer, S.; Thundat, T.; Wambsganss, M.; Wendleken, J.; White, C. W.; Wilemski, G.; Withrow, S. P.; Wolf, D.; Zhu, J. H.; Zuhr, R. A.; Zunger, A.; Lowe, S.

    1999-01-01

    This report describes important future research directions in nanoscale science, engineering and technology. It was prepared in connection with an anticipated national research initiative on nanotechnology for the twenty-first century. The research directions described are not expected to be inclusive but illustrate the wide range of research opportunities and challenges that could be undertaken through the national laboratories and their major national scientific user facilities with the support of universities and industry.

  6. Direct characterization of phase transformations and morphologies in moving reaction zones in Al/Ni nanolaminates using dynamic transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.S., E-mail: judy.kim@materials.ox.ac.uk [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Chemical Engineering and Materials Science/Molecular and Cellular Biology, University of California-Davis, 1 Shields Avenue, Davis, CA 95616 (United States); LaGrange, T.; Reed, B.W. [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Knepper, R.; Weihs, T.P. [Department of Materials Science and Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States); Browning, N.D. [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Chemical Engineering and Materials Science/Molecular and Cellular Biology, University of California-Davis, 1 Shields Avenue, Davis, CA 95616 (United States); Campbell, G.H. [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)

    2011-05-15

    Highlights: > Fast phase transformations are examined in Al/Ni reactive nanolaminates. > Results visible only by dynamic transmission electron microscopy at ns resolution. > NiAl forms under 15 ns after reaction front in all three stoichiometries studied. > DTEM imaging reveals a transient cellular morphology in nonequiatomic films. - Abstract: Phase transformations and transient morphologies are examined as exothermic formation reactions self-propagate across Al/Ni nanolaminate films. The rapid evolution of these phases and sub-micrometer morphological features requires nanoscale temporal and spatial resolution that is not available with traditional in situ electron microscopy. This work uses dynamic transmission electron microscopy to identify intermetallic products and phase morphologies, as exothermic formation reactions self-propagate in nanolaminate films grown with 3:2, 2:3 and 1:1 Al/Ni atomic ratios. Single-shot diffraction patterns with 15 ns temporal resolution reveal that the NiAl intermetallic forms within {approx}15 ns of the reaction front's arrival in all three types of films and is the only intermetallic phase to form, as the reactions self-propagate and quench very rapidly. Time-resolved imaging reveals a transient cellular morphology in the Al-rich and Ni-rich foils, but not in the equiatomic films. The cellular features in the Al-rich and Ni-rich films are attributed to a cooling trajectory through a two-phase field of liquid + NiAl.

  7. Application of exergetic sustainability index to a nano-scale irreversible Brayton cycle operating with ideal Bose and Fermi gasses

    Energy Technology Data Exchange (ETDEWEB)

    Açıkkalp, Emin, E-mail: eacikkalp@gmail.com [Department of Mechanical and Manufacturing Engineering, Engineering Faculty, Bilecik S.E. University, Bilecik (Turkey); Caner, Necmettin [Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir (Turkey)

    2015-09-25

    Highlights: • An irreversible Brayton cycle operating quantum gasses is considered. • Exergetic sustainability index is derived for nano-scale cycles. • Nano-scale effects are considered. • Calculation are conducted for irreversible cycles. • Numerical results are presented and discussed. - Abstract: In this study, a nano-scale irreversible Brayton cycle operating with quantum gasses including Bose and Fermi gasses is researched. Developments in the nano-technology cause searching the nano-scale machines including thermal systems to be unavoidable. Thermodynamic analysis of a nano-scale irreversible Brayton cycle operating with Bose and Fermi gasses was performed (especially using exergetic sustainability index). In addition, thermodynamic analysis involving classical evaluation parameters such as work output, exergy output, entropy generation, energy and exergy efficiencies were conducted. Results are submitted numerically and finally some useful recommendations were conducted. Some important results are: entropy generation and exergetic sustainability index are affected mostly for Bose gas and power output and exergy output are affected mostly for the Fermi gas by x. At the high temperature conditions, work output and entropy generation have high values comparing with other degeneracy conditions.

  8. Abstractocyte: A Visual Tool for Exploring Nanoscale Astroglial Cells

    KAUST Repository

    Mohammed, Haneen; Al-Awami, Ali K.; Beyer, Johanna; Cali, Corrado; Magistretti, Pierre J.; Pfister, Hanspeter; Hadwiger, Markus

    2017-01-01

    This paper presents Abstractocyte, a system for the visual analysis of astrocytes and their relation to neurons, in nanoscale volumes of brain tissue. Astrocytes are glial cells, i.e., non-neuronal cells that support neurons and the nervous system. The study of astrocytes has immense potential for understanding brain function. However, their complex and widely-branching structure requires high-resolution electron microscopy imaging and makes visualization and analysis challenging. Furthermore, the structure and function of astrocytes is very different from neurons, and therefore requires the development of new visualization and analysis tools. With Abstractocyte, biologists can explore the morphology of astrocytes using various visual abstraction levels, while simultaneously analyzing neighboring neurons and their connectivity. We define a novel, conceptual 2D abstraction space for jointly visualizing astrocytes and neurons. Neuroscientists can choose a specific joint visualization as a point in this space. Interactively moving this point allows them to smoothly transition between different abstraction levels in an intuitive manner. In contrast to simply switching between different visualizations, this preserves the visual context and correlations throughout the transition. Users can smoothly navigate from concrete, highly-detailed 3D views to simplified and abstracted 2D views. In addition to investigating astrocytes, neurons, and their relationships, we enable the interactive analysis of the distribution of glycogen, which is of high importance to neuroscientists. We describe the design of Abstractocyte, and present three case studies in which neuroscientists have successfully used our system to assess astrocytic coverage of synapses, glycogen distribution in relation to synapses, and astrocytic-mitochondria coverage.

  9. Abstractocyte: A Visual Tool for Exploring Nanoscale Astroglial Cells

    KAUST Repository

    Mohammed, Haneen

    2017-08-28

    This paper presents Abstractocyte, a system for the visual analysis of astrocytes and their relation to neurons, in nanoscale volumes of brain tissue. Astrocytes are glial cells, i.e., non-neuronal cells that support neurons and the nervous system. The study of astrocytes has immense potential for understanding brain function. However, their complex and widely-branching structure requires high-resolution electron microscopy imaging and makes visualization and analysis challenging. Furthermore, the structure and function of astrocytes is very different from neurons, and therefore requires the development of new visualization and analysis tools. With Abstractocyte, biologists can explore the morphology of astrocytes using various visual abstraction levels, while simultaneously analyzing neighboring neurons and their connectivity. We define a novel, conceptual 2D abstraction space for jointly visualizing astrocytes and neurons. Neuroscientists can choose a specific joint visualization as a point in this space. Interactively moving this point allows them to smoothly transition between different abstraction levels in an intuitive manner. In contrast to simply switching between different visualizations, this preserves the visual context and correlations throughout the transition. Users can smoothly navigate from concrete, highly-detailed 3D views to simplified and abstracted 2D views. In addition to investigating astrocytes, neurons, and their relationships, we enable the interactive analysis of the distribution of glycogen, which is of high importance to neuroscientists. We describe the design of Abstractocyte, and present three case studies in which neuroscientists have successfully used our system to assess astrocytic coverage of synapses, glycogen distribution in relation to synapses, and astrocytic-mitochondria coverage.

  10. Finite-element modeling of spontaneous emission of a quantum emitter at nanoscale proximity to plasmonic waveguides

    DEFF Research Database (Denmark)

    Chen, Yuntian; Nielsen, Torben Roland; Gregersen, Niels

    2010-01-01

    of the plasmonic waveguide can be arbitrary. The fraction of the energy coupled to the plasmonic mode can be calculated exactly, which can be used to determine the efficiency with which single optical plasmons are generated. We apply our numerical method to calculate the coupling of a quantum emitter......We develop a self-consistent finite-element method to quantitatively study spontaneous emission from emitters in nanoscale proximity of plasmonic waveguides. In the model, it is assumed that only one guided mode is dominatingly excited by the quantum emitter, while the cross section...

  11. Nanoscale semiconductor-insulator-metal core/shell heterostructures: facile synthesis and light emission

    Science.gov (United States)

    Li, Gong Ping; Chen, Rui; Guo, Dong Lai; Wong, Lai Mun; Wang, Shi Jie; Sun, Han Dong; Wu, Tom

    2011-08-01

    Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications.Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in

  12. Ferroelectric crystals for photonic applications including nanoscale fabrication and characterization techniques

    CERN Document Server

    Ferraro, Pietro; De Natale, Paolo

    2015-01-01

    This book details the latest achievements in ferroelectric domain engineering and characterization at micro- and nano-scale dimensions and periods. It combines basic research of magnetic materials with device and production orientation.

  13. Phase diagram of nanoscale alloy particles used for vapor-liquid-solid growth of semiconductor nanowires.

    Science.gov (United States)

    Sutter, Eli; Sutter, Peter

    2008-02-01

    We use transmission electron microscopy observations to establish the parts of the phase diagram of nanometer sized Au-Ge alloy drops at the tips of Ge nanowires (NWs) that determine their temperature-dependent equilibrium composition and, hence, their exchange of semiconductor material with the NWs. We find that the phase diagram of the nanoscale drop deviates significantly from that of the bulk alloy, which explains discrepancies between actual growth results and predictions on the basis of the bulk-phase equilibria. Our findings provide the basis for tailoring vapor-liquid-solid growth to achieve complex one-dimensional materials geometries.

  14. Ion beam modification of biological materials in nanoscale

    Science.gov (United States)

    Yu, L. D.; Anuntalabhochai, S.

    2012-07-01

    Ion interaction with biological objects in nanoscale is a novel research area stemming from applications of low-energy ion beams in biotechnology and biomedicine. Although the ion beam applications in biotechnology and biomedicine have achieved great successes, many mechanisms remain unclear and many new applications are to be explored. We have carried out some research on exploring the mechanisms and new applications besides attaining ion beam induction of mutation breeding and gene transformation. In the studies on the mechanisms, we focused our investigations on the direct interaction in nanoscale between ions and biological living materials. Our research topics have included the low-energy ion range in DNA, low-energy ion or neutral beam bombardment effect on DNA topological form change and mutation, low-energy ion or neutral beam bombardment effect on the cell envelope and gene transformation, and molecular dynamics simulation of ultra-low-energy ion irradiation of DNA. In the exploration of new applications, we have started experiments on ion irradiation or bombardment, in the nanoscaled depth or area, of human cells for biomedical research. This paper introduces our experiments and reports interesting results.

  15. Ion beam modification of biological materials in nanoscale

    International Nuclear Information System (INIS)

    Yu, L.D.; Anuntalabhochai, S.

    2012-01-01

    Ion interaction with biological objects in nanoscale is a novel research area stemming from applications of low-energy ion beams in biotechnology and biomedicine. Although the ion beam applications in biotechnology and biomedicine have achieved great successes, many mechanisms remain unclear and many new applications are to be explored. We have carried out some research on exploring the mechanisms and new applications besides attaining ion beam induction of mutation breeding and gene transformation. In the studies on the mechanisms, we focused our investigations on the direct interaction in nanoscale between ions and biological living materials. Our research topics have included the low-energy ion range in DNA, low-energy ion or neutral beam bombardment effect on DNA topological form change and mutation, low-energy ion or neutral beam bombardment effect on the cell envelope and gene transformation, and molecular dynamics simulation of ultra-low-energy ion irradiation of DNA. In the exploration of new applications, we have started experiments on ion irradiation or bombardment, in the nanoscaled depth or area, of human cells for biomedical research. This paper introduces our experiments and reports interesting results.

  16. Intelligent Design of Nano-Scale Molecular Imaging Agents

    Directory of Open Access Journals (Sweden)

    Takeaki Ozawa

    2012-12-01

    Full Text Available Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs, biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on–off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents.

  17. Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings

    Science.gov (United States)

    Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B.

    2018-04-01

    Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO2) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

  18. Radiation synthesis of the nano-scale materials

    Energy Technology Data Exchange (ETDEWEB)

    Yonghong, Ni; Zhicheng, Zhang; Xuewu, Ge; Xiangling, Xu [Department of Applied Chemistry, Univ. of Science and Technology of China, Hefei (China)

    2000-03-01

    Some recent research jobs on fabricating the nano-scale materials via {gamma}-irradiation in our laboratory are simply summarized in this paper. The main contents contain four aspects: (1) the preparation of metal alloy - powders; (2) the fabrication of polymer -metal nano-composites in aqueous solution, micro-emulsion and emulsion systems; (3) the synthesis of metal sulfide nano-particles and (4) the preparation of the ordered nano-structure materials. The corresponding preparation processes are also simply described. (author)

  19. Radiation synthesis of the nano-scale materials

    International Nuclear Information System (INIS)

    Ni Yonghong; Zhang Zhicheng; Ge Xuewu; Xu Xiangling

    2000-01-01

    Some recent research jobs on fabricating the nano-scale materials via γ-irradiation in our laboratory are simply summarized in this paper. The main contents contain four aspects: (1) the preparation of metal alloy - powders; (2) the fabrication of polymer -metal nano-composites in aqueous solution, micro-emulsion and emulsion systems; (3) the synthesis of metal sulfide nano-particles and (4) the preparation of the ordered nano-structure materials. The corresponding preparation processes are also simply described. (author)

  20. Nanoscale aluminum concaves for light-trapping in organic thin-films

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jaroslaw; Adam, Jost; Cielecki, Pawel Piotr

    2016-01-01

    Anodic aluminum oxide (AAO) templates, fabricated from oxalic acid and phosphoric acid, lead to non-periodic nanoscale concave structures in their underlying aluminum layer, which are investigated for their field-enhancement properties by applying a thin-film polymer coating based laser ablation...

  1. Manufacturing at Nanoscale: Top-Down, Bottom-up and System Engineering

    International Nuclear Information System (INIS)

    Zhang Xiang; Sun Cheng; Fang, Nicholas

    2004-01-01

    The current nano-technology revolution is facing several major challenges: to manufacture nanodevices below 20 nm, to fabricate three-dimensional complex nano-structures, and to heterogeneously integrate multiple functionalities. To tackle these grand challenges, the Center for Scalable and Integrated NAno-Manufacturing (SINAM), a NSF Nanoscale Science and Engineering Center, set its goal to establish a new manufacturing paradigm that integrates an array of new nano-manufacturing technologies, including the plasmonic imaging lithography and ultramolding imprint lithography aiming toward critical resolution of 1-10 nm and the hybrid top-down and bottom-up technologies to achieve massively parallel integration of heterogeneous nanoscale components into higher-order structures and devices. Furthermore, SINAM will develop system engineering strategies to scale-up the nano-manufacturing technologies. SINAMs integrated research and education platform will shed light to a broad range of potential applications in computing, telecommunication, photonics, biotechnology, health care, and national security

  2. Imaging the Nanoscale Band Structure of Topological Sb

    OpenAIRE

    Soumyanarayanan, Anjan; Yee, Michael M.; He, Yang; Lin, Hsin; Gardner, Dillon R.; Bansil, Arun; Lee, Young S.; Hoffman, Jennifer E.

    2013-01-01

    Many promising building blocks of future electronic technology - including non-stoichiometric compounds, strongly correlated oxides, and strained or patterned films - are inhomogeneous on the nanometer length scale. Exploiting the inhomogeneity of such materials to design next-generation nanodevices requires a band structure probe with nanoscale spatial resolution. To address this demand, we report the first simultaneous observation and quantitative reconciliation of two candidate probes - La...

  3. Nanoscale biophysics of the cell

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2018-01-01

    Macroscopic cellular structures and functions are generally investigated using biological and biochemical approaches. But these methods are no longer adequate when one needs to penetrate deep into the small-scale structures and understand their functions. The cell is found to hold various physical structures, molecular machines, and processes that require physical and mathematical approaches to understand and indeed manipulate them. Disorders in general cellular compartments, perturbations in single molecular structures, drug distribution therein, and target specific drug-binding, etc. are mostly physical phenomena. This book will show how biophysics has revolutionized our way of addressing the science and technology of nanoscale structures of cells, and also describes the potential for manipulating the events that occur in them.

  4. Alternative chemical-based synthesis routes and characterization of nano-scale particles

    International Nuclear Information System (INIS)

    Brocchi, E.A.; Motta, M.S.; Solorzano, I.G.; Jena, P.K.; Moura, F.J.

    2004-01-01

    Different nano-scale particles have been synthesized by alternative routes: nitrates dehydratation and oxide, or co-formed oxides, reduction by hydrogen. Chemical-based synthesis routes are described and thermodynamics studies and kinetics data are presented to support the feasibility for obtaining single-phase oxides and co-formed two-phase oxides. In addition, the reduction reaction has been applied to successfully produce metal/ceramic nanocomposites. Structural characterization has been carried out by means of X-ray diffraction and, more extensively, transmission electron microscopy operating in conventional diffraction contrast mode (CTEM) and high-resolution mode (HRTEM). Nano-scale size distribution of oxide particles is well demonstrated together with their defect-free structure in the lower range, around 20 nm, size. Structural features related to the synthesized nano-composites are also presented

  5. Ring substituents mediate the morphology of PBDTTPD-PCBM bulk-heterojunction solar cells

    KAUST Repository

    Warnan, Julien

    2014-04-08

    Among π-conjugated polymer donors for efficient bulk-heterojunction (BHJ) solar cell applications, poly(benzo[1,2-b:4,5-b′]dithiophene- thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers yield some of the highest open-circuit voltages (VOC, ca. 0.9 V) and fill-factors (FF, ca. 70%) in conventional (single-cell) BHJ devices with PCBM acceptors. In PBDTTPD, side chains of varying size and branching affect polymer self-assembly, nanostructural order, and impact material performance. However, the role of the polymer side-chain pattern in the intimate mixing between polymer donors and PCBM acceptors, and on the development of the BHJ morphology is in general less understood. In this contribution, we show that ring substituents such as furan (F), thiophene (T) and selenophene (S)-incorporated into the side chains of PBDTTPD polymers-can induce significant and, of importance, very different morphological effects in BHJs with PCBM. A combination of experimental and theoretical (via density functional theory) characterizations sheds light on how varying the heteroatom of the ring substituents impacts (i) the preferred side-chain configurations and (ii) the ionization, electronic, and optical properties of the PBDTTPD polymers. In parallel, we find that the PBDT(X)TPD analogs (with X = F, T, or S) span a broad range of power conversion efficiencies (PCEs, 3-6.5%) in optimized devices with improved thin-film morphologies via the use of 1,8-diiodooctane (DIO), and discuss that persistent morphological impediments at the nanoscale can be at the origin of the spread in PCE across optimized PBDT(X)TPD-based devices. With their high VOC ∼1 V, PBDT(X)TPD polymers are promising candidates for use in the high-band gap cell of tandem solar cells. © 2014 American Chemical Society.

  6. Ring substituents mediate the morphology of PBDTTPD-PCBM bulk-heterojunction solar cells

    KAUST Repository

    Warnan, Julien; El Labban, Abdulrahman; Cabanetos, Clement; Hoke, Eric T.; Shukla, Pradeep Kumar; Risko, Chad; Bré das, Jean Luc; McGehee, Michael D.; Beaujuge, Pierre

    2014-01-01

    Among π-conjugated polymer donors for efficient bulk-heterojunction (BHJ) solar cell applications, poly(benzo[1,2-b:4,5-b′]dithiophene- thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers yield some of the highest open-circuit voltages (VOC, ca. 0.9 V) and fill-factors (FF, ca. 70%) in conventional (single-cell) BHJ devices with PCBM acceptors. In PBDTTPD, side chains of varying size and branching affect polymer self-assembly, nanostructural order, and impact material performance. However, the role of the polymer side-chain pattern in the intimate mixing between polymer donors and PCBM acceptors, and on the development of the BHJ morphology is in general less understood. In this contribution, we show that ring substituents such as furan (F), thiophene (T) and selenophene (S)-incorporated into the side chains of PBDTTPD polymers-can induce significant and, of importance, very different morphological effects in BHJs with PCBM. A combination of experimental and theoretical (via density functional theory) characterizations sheds light on how varying the heteroatom of the ring substituents impacts (i) the preferred side-chain configurations and (ii) the ionization, electronic, and optical properties of the PBDTTPD polymers. In parallel, we find that the PBDT(X)TPD analogs (with X = F, T, or S) span a broad range of power conversion efficiencies (PCEs, 3-6.5%) in optimized devices with improved thin-film morphologies via the use of 1,8-diiodooctane (DIO), and discuss that persistent morphological impediments at the nanoscale can be at the origin of the spread in PCE across optimized PBDT(X)TPD-based devices. With their high VOC ∼1 V, PBDT(X)TPD polymers are promising candidates for use in the high-band gap cell of tandem solar cells. © 2014 American Chemical Society.

  7. A novel nanoscale-dispersed eye ointment for the treatment of dry eye disease

    International Nuclear Information System (INIS)

    Zhang, Wenjian; Liu, Chang; Wei, Gang; Lu, Weiyue; Wang, Yan; Lee, Benjamin Tak Kwong

    2014-01-01

    A novel nanoscale-dispersed eye ointment (NDEO) for the treatment of severe evaporative dry eye has been successfully developed. The excipients used as semisolid lipids were petrolatum and lanolin, as used in conventional eye ointment, which were coupled with medium-chain triglycerides (MCT) as a liquid lipid; both phases were then dispersed in polyvinyl pyrrolidone solution to form a nanodispersion. Single-factor experiments were conducted to optimize the formulations. A transmission electron micrograph showed that the ointment matrix was entrapped in the nanoemulsion of MCT, with a mean particle size of about 100 nm. The optimized formulation of NDEO was stable when stored for six months at 4 °C, and demonstrated no cytotoxicity to human corneal epithelial cells when compared with commercial polymer-based artificial tears (Tears Natural ®  Forte). The therapeutic effects of NDEO were evaluated on a mouse model with ‘dry eye’. Both the tear break-up time and fluorescein staining demonstrated therapeutic improvement, displaying a trend of positive correlation with higher concentrations of ointment matrix in the NDEO formulations compared to a marketed product. Histological evaluation demonstrated that the NDEO restored the normal corneal and conjunctival morphology and is safe for ophthalmic application. (paper)

  8. Phonon Transport through Nanoscale Contact in Tip-Based Thermal Analysis of Nanomaterials.

    Science.gov (United States)

    Dulhani, Jay; Lee, Bong Jae

    2017-07-28

    Nanomaterials have been actively employed in various applications for energy and sustainability, such as biosensing, gas sensing, solar thermal energy conversion, passive radiative cooling, etc. Understanding thermal transports inside such nanomaterials is crucial for optimizing their performance for different applications. In order to probe the thermal transport inside nanomaterials or nanostructures, tip-based nanoscale thermometry has often been employed. It has been well known that phonon transport in nanometer scale is fundamentally different from that occurred in macroscale. Therefore, Fourier's law that relies on the diffusion approximation is not ideally suitable for describing the phonon transport occurred in nanostructures and/or through nanoscale contact. In the present study, the gray Boltzmann transport equation (BTE) is numerically solved using finite volume method. Based on the gray BTE, phonon transport through the constriction formed by a probe itself as well as the nanoscale contact between the probe tip and the specimen is investigated. The interaction of a probe and a specimen (i.e., treated as a substrate) is explored qualitatively by analyzing the temperature variation in the tip-substrate configuration. Besides, each contribution of a probe tip, tip-substrate interface, and a substrate to the thermal resistance are analyzed for wide ranges of the constriction ratio of the probe.

  9. Destructive impact of molecular noise on nanoscale electrochemical oscillators

    Science.gov (United States)

    Cosi, Filippo G.; Krischer, Katharina

    2017-06-01

    We study the loss of coherence of electrochemical oscillations on meso- and nanosized electrodes with numeric simulations of the electrochemical master equation for a prototypical electrochemical oscillator, the hydrogen peroxide reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the electrode potential changes whenever a stochastic electron-transfer event takes place. Electrochemical reaction rate coefficients depend exponentially on the electrode potential and become thus fluctuating quantities as well. Therefore, also the transition rates between system states become time-dependent which constitutes a fundamental difference to purely chemical nanoscale oscillators. Three implications are demonstrated: (a) oscillations and steady states shift in phase space with decreasing system size, thereby also decreasing considerably the oscillating parameter regions; (b) the minimal number of molecules necessary to support correlated oscillations is more than 10 times as large as for nanoscale chemical oscillators; (c) the relation between correlation time and variance of the period of the oscillations predicted for chemical oscillators in the weak noise limit is only fulfilled in a very restricted parameter range for the electrochemical nano-oscillator.

  10. A hard X-ray nanoprobe beamline for nanoscale microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Winarski, Robert P., E-mail: winarski@anl.gov; Holt, Martin V. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Rose, Volker [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Fuesz, Peter; Carbaugh, Dean; Benson, Christa; Shu, Deming; Kline, David; Stephenson, G. Brian; McNulty, Ian [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States); Maser, Jörg [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60441 (United States)

    2012-11-01

    The Hard X-ray Nanoprobe Beamline is a precision platform for scanning probe and full-field microscopy with 3–30 keV X-rays. A combination of high-stability X-ray optics and precision motion sensing and control enables detailed studies of the internal features of samples with resolutions approaching 30 nm. The Hard X-ray Nanoprobe Beamline (or Nanoprobe Beamline) is an X-ray microscopy facility incorporating diffraction, fluorescence and full-field imaging capabilities designed and operated by the Center for Nanoscale Materials and the Advanced Photon Source at Sector 26 of the Advanced Photon Source at Argonne National Laboratory. This facility was constructed to probe the nanoscale structure of biological, environmental and material sciences samples. The beamline provides intense focused X-rays to the Hard X-ray Nanoprobe (or Nanoprobe) which incorporates Fresnel zone plate optics and a precision laser sensing and control system. The beamline operates over X-ray energies from 3 to 30 keV, enabling studies of most elements in the periodic table, with a particular emphasis on imaging transition metals.

  11. Globular, Sponge-like to Layer-like Morphological Transition in 1-n-Alkyl-3-methylimidazolium Octylsulfate Ionic Liquid Homologous Series.

    Science.gov (United States)

    Kapoor, Utkarsh; Shah, Jindal K

    2018-01-11

    Segregation of polar and nonpolar domains in ionic liquids for which either the cation or anion is responsible for inducing nonpolar domains is well understood. On the other hand, information regarding the nanoscale heterogeneities originating due to the presence of nonpolar content on both the ions is rudimentary at this point. The present contribution is aimed at addressing this question and focuses on a molecular dynamics simulation study to probe nanoscale structural and aggregation features of the 1-n-alkyl-3-methylimidazolium [C n mim] octylsulfate [C 8 SO 4 ] ionic liquid homologous series (n = 2, 4, 6, 8, 10, and 12). The objective of this work is to determine the effect of increasing alkyl chain length in the cation on nonpolar domain formation, especially when the alkyl chain lengths from both the ions participate in defining such domains. The results indicate that all the ionic liquids form nonpolar domains, morphology of which gradually changes from globular, sponge-like to layer-like structure with increase in the cationic alkyl chain length. The length of the nonpolar domains calculated from the total structure factor for [C 10 mim][C 8 SO 4 ] is considerably higher than that reported for other imidazolium-based ionic liquid containing smaller anions. The structure factor for [C 12 mim][C 8 SO 4 ] ionic liquid contains multiple intermediate peaks separating the charge alternation peak and pre-peak, which points to nonpolar domains of varying lengths, an observation that remains to be validated. Analysis of the heterogeneous order parameters and orientational correlation functions of the alkyl chains further suggests an increase in the spatial heterogeneity and long-range order along the homologous series. The origin of rich diversity of structures obtained by introducing nonpolar content on both the ions is discussed.

  12. In situ observations of crack arrest and bridging by nanoscale twins in copper thin films

    International Nuclear Information System (INIS)

    Kim, Seong-Woong; Li Xiaoyan; Gao Huajian; Kumar, Sharvan

    2012-01-01

    In situ tensile experiments in a transmission electron microscope revealed that micro-cracks in ultrafine grained, free-standing, thin copper foils containing nanoscale twins initiated in matrix domains separated by the twins and then arrested at twin boundaries as twin boundary sliding proceeded. The adjacent microcracks eventually coalesced through shear failure of the bridging twins. To investigate the atomic mechanism of this rarely seen nanoscale crack bridging behavior, molecular dynamics simulations were performed to show that during crack propagation twin boundaries are impinged upon by numerous dislocations from the plastically deforming matrix. These dislocations react at the interface and evolve into substantially impenetrable dislocation walls that strongly confine crack nucleation and resist crack propagation, leading to the experimentally observed crack bridging behavior. The present results raise an approach to significantly toughening polycrystalline thin films by incorporating nanoscale twin structures into individual grains that serve as crack bridging ligaments.

  13. Experimental Study of Electron and Phonon Dynamics in Nanoscale Materials by Ultrafast Laser Time-Domain Spectroscopy

    Science.gov (United States)

    Shen, Xiaohan

    With the rapid advances in the development of nanotechnology, nowadays, the sizes of elementary unit, i.e. transistor, of micro- and nanoelectronic devices are well deep into nanoscale. For the pursuit of cheaper and faster nanoscale electronic devices, the size of transistors keeps scaling down. As the miniaturization of the nanoelectronic devices, the electrical resistivity increases dramatically, resulting rapid growth in the heat generation. The heat generation and limited thermal dissipation in nanoscale materials have become a critical problem in the development of the next generation nanoelectronic devices. Copper (Cu) is widely used conducting material in nanoelectronic devices, and the electron-phonon scattering is the dominant contributor to the resistivity in Cu nanowires at room temperature. Meanwhile, phonons are the main carriers of heat in insulators, intrinsic and lightly doped semiconductors. The thermal transport is an ensemble of phonon transport, which strongly depends on the phonon frequency. In addition, the phonon transport in nanoscale materials can behave fundamentally different than in bulk materials, because of the spatial confinement. However, the size effect on electron-phonon scattering and frequency dependent phonon transport in nanoscale materials remain largely unexplored, due to the lack of suitable experimental techniques. This thesis is mainly focusing on the study of carrier dynamics and acoustic phonon transport in nanoscale materials. The weak photothermal interaction in Cu makes thermoreflectance measurement difficult, we rather measured the reflectivity change of Cu induced by absorption variation. We have developed a method to separately measure the processes of electron-electron scattering and electron-phonon scattering in epitaxial Cu films by monitoring the transient reflectivity signal using the resonant probe with particular wavelengths. The enhancement on electron-phonon scattering in epitaxial Cu films with thickness

  14. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

    International Nuclear Information System (INIS)

    Patterson, B.M.; Henderson, K.C.; Gibbs, P.J.; Imhoff, S.D.; Clarke, A.J.

    2014-01-01

    X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and

  15. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, B.M., E-mail: bpatterson@lanl.gov; Henderson, K.C.; Gibbs, P.J.; Imhoff, S.D.; Clarke, A.J.

    2014-09-15

    X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and

  16. Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures

    Science.gov (United States)

    Kaul, Anupama B.; Megerian, Krikor G.; Von Allmen, Paul A.; Baron, Richard L.

    2010-01-01

    Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are

  17. Special Issue on the Second International Workshop on Micro- and Nano-Scale Thermal Radiation

    Science.gov (United States)

    Zhang, Zhuomin; Liu, Linhua; Zhu, Qunzhi; Mengüç, M. Pinar

    2015-06-01

    Micro- and nano-scale thermal radiation has become one of the fastest growing research areas because of advances in nanotechnology and the development of novel materials. The related research and development includes near-field radiation transfer, spectral and directional selective emitters and receivers, plasmonics, metamaterials, and novel nano-scale fabrication techniques. With the advances in these areas, important applications in energy harvesting such as solar cells and thermophotovoltaics, nanomanufacturing, biomedical sensing, thermal imaging as well as data storage with the localized heating/cooling have been pushed to higher levels.

  18. In situ morphology studies of the mechanism for solution additive effects on the formation of bulk heterojunction films

    KAUST Repository

    Richter, Lee J.

    2014-09-29

    The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order/quality of the respective phases. These critical morphological features develop dynamically during film formation, and it has become common practice to control them by the introduction of processing additives. Here, in situ grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) studies of the development of order in BHJ films formed from the donor polymer poly(3-hexylthiophene) and acceptor phenyl-C61-butyric acid methyl ester under the influence of two common additives, 1,8-octanedithiol and 1-chloronaphthalene, are reported. By comparing optical aggregation to crystallization and using GISAXS to determine the number and nature of phases present during drying, two common mechanisms by which the additives increase P3HT crystallinity are identified. Additives accelerate the appearance of pre-crystalline nuclei by controlling solvent quality and allow for extended crystal growth by delaying the onset of PCBM-induced vitrification. The glass transition effects vary system-to-system and may be correlated to the number and composition of phases present during drying. Synchrotron X-ray scattering measurements of nanoscale structure evolution during the drying of polymer-fullerene photovoltaic films are described. Changes in the number and nature of phases, as well as the order within them, reveals the mechanisms by which formulation additives promote structural characteristics leading to higher power conversion efficiencies.

  19. In situ morphology studies of the mechanism for solution additive effects on the formation of bulk heterojunction films

    KAUST Repository

    Richter, Lee J.; DeLongchamp., Dean M.; Bokel, Felicia A.; Engmann, Sebastian; Chou, Kang Wei; Amassian, Aram; Schaible, Eric G.; Hexemer, Alexander

    2014-01-01

    The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order/quality of the respective phases. These critical morphological features develop dynamically during film formation, and it has become common practice to control them by the introduction of processing additives. Here, in situ grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) studies of the development of order in BHJ films formed from the donor polymer poly(3-hexylthiophene) and acceptor phenyl-C61-butyric acid methyl ester under the influence of two common additives, 1,8-octanedithiol and 1-chloronaphthalene, are reported. By comparing optical aggregation to crystallization and using GISAXS to determine the number and nature of phases present during drying, two common mechanisms by which the additives increase P3HT crystallinity are identified. Additives accelerate the appearance of pre-crystalline nuclei by controlling solvent quality and allow for extended crystal growth by delaying the onset of PCBM-induced vitrification. The glass transition effects vary system-to-system and may be correlated to the number and composition of phases present during drying. Synchrotron X-ray scattering measurements of nanoscale structure evolution during the drying of polymer-fullerene photovoltaic films are described. Changes in the number and nature of phases, as well as the order within them, reveals the mechanisms by which formulation additives promote structural characteristics leading to higher power conversion efficiencies.

  20. Boron-doped Diamond Electrodes: Electrochemical, Atomic Force Microscopy and Raman Study towards Corrosion-modifications at Nanoscale

    International Nuclear Information System (INIS)

    Kavan, Ladislav; Vlckova Zivcova, Zuzana; Petrak, Vaclav; Frank, Otakar; Janda, Pavel; Tarabkova, Hana; Nesladek, Milos; Mortet, Vincent

    2015-01-01

    Highlights: • B-doped diamond is nanostructured by corrosion-driven modifications occurring at carbonaceous impurity sites (sp 2 -carbons). • The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved. • In contrast to all usual sp 2 carbons, the Raman spectra of B-doped diamond electrodes do not change upon electrochemical charging/discharging. - Abstract: Comparative studies of boron-doped diamonds electrodes (polycrystalline, single-crystalline, H-/O-terminated, and with different sp 3 /sp 2 ratios) indicate morphological modifications of diamond which are initiated by corrosion at nanoscale. In-situ electrochemical AFM imaging evidences that the textural changes start at non-diamond carbonaceous impurity sites treated at high positive potentials (>2.2 V vs. Ag/AgCl). The primary perturbations subsequently develop into sub-micron-sized craters. Raman spectroscopy shows that the primary erosion site is graphite-like (sp 2 -carbon), which is preferentially removed by anodic oxidation. Other non-diamond impurity, viz. tetrahedral amorphous carbon (t-aC), is less sensitive to oxidative decomposition. The diamond-related Raman features, including the B-doping-assigned modes, are intact during reversible electrochemical charging/discharging, which is a salient difference from all usual sp 2 -carbons. The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved for a model redox couple, Fe 3+/2+ . Electrochemical impedance spectra were fitted to six different equivalent circuits. The determination of acceptor concentrations is feasible even for highly-doped diamond electrodes.

  1. Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

    Science.gov (United States)

    Biyikli, Necmi; Haider, Ali

    2017-09-01

    In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

  2. Facilitation of Nanoscale Thermal Transport by Hydrogen Bonds

    OpenAIRE

    Zhang, Lin

    2017-01-01

    Thermal transport performance at the nanoscale and/or of biomaterials is essential to the success of many new technologies including nanoelectronics, biomedical devices, and various nanocomposites. Due to complicated microstructures and chemical bonding, thermal transport process in these materials has not been well understood yet. In terms of chemical bonding, it is well known that the strength of atomic bonding can significantly affect thermal transport across materials or across interfaces...

  3. Nanoscale strengthening mechanisms in metallic thin film systems

    Science.gov (United States)

    Schoeppner, Rachel Lynn

    Nano-scale strengthening mechanisms for thin films were investigated for systems governed by two different strengthening techniques: nano-laminate strengthening and oxide dispersion strengthening. Films were tested under elevated temperature conditions to investigate changes in deformation mechanisms at different operating temperatures, and the structural stability. Both systems exhibit remarkable stability after annealing and thus long-term reliability. Nano-scale metallic multilayers with smaller layer thicknesses show a greater relative resistance to decreasing strength at higher temperature testing conditions than those with larger layer thicknesses. This is seen in both Cu/Ni/Nb multilayers as well as a similar tri-component bi-layer system (Cu-Ni/Nb), which removed the coherent interface from the film. Both nanoindentation and micro-pillar compression tests investigated the strain-hardening ability of these two systems to determine what role the coherent interface plays in this mechanism. Tri-layer films showed a higher strain-hardening ability as the layer thickness decreased and a higher strain-hardening exponent than the bi-layer system: verifying the presence of a coherent interface increases the strain-hardening ability of these multilayer systems. Both systems exhibited hardening of the room temperature strength after annealing, suggesting a change in microstructure has occurred, unlike that seen in other multilayer systems. Oxide dispersion strengthened Au films showed a marked increase in hardness and wear resistance with the addition of ZnO particles. The threshold for stress-induced grain-refinement as opposed to grain growth is seen at concentrations of at least 0.5 vol%. These systems exhibited stable microstructures during thermal cycling in films containing at least 1.0%ZnO. Nanoindentation experiments show the drop in hardness following annealing is almost completely attributed to the resulting grain growth. Four-point probe resistivity

  4. Exploring the Optical and Morphological Properties of Ag and Ag/TiO2 Nanocomposites Grown by Supersonic Cluster Beam Deposition

    Directory of Open Access Journals (Sweden)

    Emanuele Cavaliere

    2017-12-01

    Full Text Available Nanocomposite systems and nanoparticle (NP films are crucial for many applications and research fields. The structure-properties correlation raises complex questions due to the collective structure of these systems, often granular and porous, a crucial factor impacting their effectiveness and performance. In this framework, we investigate the optical and morphological properties of Ag nanoparticles (NPs films and of Ag NPs/TiO2 porous matrix films, one-step grown by supersonic cluster beam deposition. Morphology and structure of the Ag NPs film and of the Ag/TiO2 (Ag/Ti 50-50 nanocomposite are related to the optical properties of the film employing spectroscopic ellipsometry (SE. We employ a simple Bruggeman effective medium approximation model, corrected by finite size effects of the nano-objects in the film structure to gather information on the structure and morphology of the nanocomposites, in particular porosity and average NPs size for the Ag/TiO2 NP film. Our results suggest that SE is a simple, quick and effective method to measure porosity of nanoscale films and systems, where standard methods for measuring pore sizes might not be applicable.

  5. Assembly and structural analysis of a covalently closed nano-scale DNA cage

    DEFF Research Database (Denmark)

    Andersen, Félicie Faucon; Knudsen, Bjarne; Oliveira, Cristiano Luis Pinto De

    2008-01-01

    for investigations of DNA-interacting enzymes. More recently, strategies for synthesis of more complex two-dimensional (2D) and 3D DNA structures have emerged. However, the building of such structures is still in progress and more experiences from different research groups and different fields of expertise...... be described as a nano-scale DNA cage, Hence, in theory it could hold proteins or other bio-molecules to enable their investigation in certain harmful environments or even allow their organization into higher order structures...... The inherent properties of DNA as a stable polymer with unique affinity for partner molecules determined by the specific Watson-Crick base pairing makes it an ideal component in self-assembling structures. This has been exploited for decades in the design of a variety of artificial substrates...

  6. In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

    Directory of Open Access Journals (Sweden)

    de Oliveira Hansen Roana

    2011-01-01

    Full Text Available Abstract Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate on silicon dioxide patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens the possibility for large-scale optoelectronic device fabrication.

  7. Morphology of a Wetland Stream

    Science.gov (United States)

    Jurmu; Andrle

    1997-11-01

    / Little attention has been paid to wetland stream morphology in the geomorphological and environmental literature, and in the recently expanding wetland reconstruction field, stream design has been based primarily on stream morphologies typical of nonwetland alluvial environments. Field investigation of a wetland reach of Roaring Brook, Stafford, Connecticut, USA, revealed several significant differences between the morphology of this stream and the typical morphology of nonwetland alluvial streams. Six morphological features of the study reach were examined: bankfull flow, meanders, pools and riffles, thalweg location, straight reaches, and cross-sectional shape. It was found that bankfull flow definitions originating from streams in nonwetland environments did not apply. Unusual features observed in the wetland reach include tight bends and a large axial wavelength to width ratio. A lengthy straight reach exists that exceeds what is typically found in nonwetland alluvial streams. The lack of convex bank point bars in the bends, a greater channel width at riffle locations, an unusual thalweg location, and small form ratios (a deep and narrow channel) were also differences identified. Further study is needed on wetland streams of various regions to determine if differences in morphology between alluvial and wetland environments can be applied in order to improve future designs of wetland channels.KEY WORDS: Stream morphology; Wetland restoration; Wetland creation; Bankfull; Pools and riffles; Meanders; Thalweg

  8. Resolving ultrafast exciton migration in organic solids at the nanoscale

    Science.gov (United States)

    Ginsberg, Naomi

    The migration of Frenkel excitons, tightly-bound electron-hole pairs, in photosynthesis and in organic semiconducting films is critical to the efficiency of natural and artificial light harvesting. While these materials exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton migration lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are smaller than the optical diffraction limit, we adapt far-field super-resolution fluorescence imaging to uncover the correlations between the structural and energetic landscapes that the excitons explore. By combining the ultrafast super-resolved measurements with exciton hopping simulations we furthermore specify the nature (in addition to the extent) of exciton migration as a function of the intrinsic and ensemble chromophore energy scales that determine a spatio-energetic landscape for migration. In collaboration with: Samuel Penwell, Lucas Ginsberg, University of California, Berkeley and Rodrigo Noriega University of Utah.

  9. [Limitations and controversies in determining the predictive value of oocyte and embryo morphology criteria].

    Science.gov (United States)

    Figueira, Rita de Cássia Savio; Aoki, Tsutomu; Borges Junior, Edson

    2015-11-01

    In order to increase the success rate of in vitro fertilization cycles, several studies have focused on the identification of the embryo with higher implantation potential. Despite recent advances in the reproductive medicine, based on the OMICs technology, routinely applicable methodologies are still needed. Thus, in most fertilization centers embryo selection for transfer is still based on morphological parameters evaluated under light microscopy. Several morphological parameters may be evaluated, ranging from the pronuclear to blastocyst stage. In general, despite the day of transfer, some criteria are suggested to present a predictive value for embryo viability when analyzed independently or combined. However, the subjectivity of morphological evaluation, as well as the wide diversity of embryo classification systems used by different fertilization centers shows contrasting results, making the implementation of a consensus regarding different morphological criteria and their predictive value a difficult task. The optimization of embryo selection represents a large potential to increase treatment success rates, allowing the transfer of a reduced number of embryos and minimizing the risks of multiple pregnancy.

  10. Brain-like associative learning using a nanoscale non-volatile phase change synaptic device array

    Directory of Open Access Journals (Sweden)

    Sukru Burc Eryilmaz

    2014-07-01

    Full Text Available Recent advances in neuroscience together with nanoscale electronic device technology have resulted in huge interests in realizing brain-like computing hardwares using emerging nanoscale memory devices as synaptic elements. Although there has been experimental work that demonstrated the operation of nanoscale synaptic element at the single device level, network level studies have been limited to simulations. In this work, we demonstrate, using experiments, array level associative learning using phase change synaptic devices connected in a grid like configuration similar to the organization of the biological brain. Implementing Hebbian learning with phase change memory cells, the synaptic grid was able to store presented patterns and recall missing patterns in an associative brain-like fashion. We found that the system is robust to device variations, and large variations in cell resistance states can be accommodated by increasing the number of training epochs. We illustrated the tradeoff between variation tolerance of the network and the overall energy consumption, and found that energy consumption is decreased significantly for lower variation tolerance.

  11. Processing used nuclear fuel with nanoscale control of uranium and ultrafiltration

    Energy Technology Data Exchange (ETDEWEB)

    Wylie, Ernest M.; Peruski, Kathryn M.; Prizio, Sarah E. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Bridges, Andrea N.A.; Rudisill, Tracy S.; Hobbs, David T. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Phillip, William A. [Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Burns, Peter C., E-mail: pburns@nd.edu [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2016-05-15

    Current separation and purification technologies utilized in the nuclear fuel cycle rely primarily on liquid–liquid extraction and ion-exchange processes. Here, we report a laboratory-scale aqueous process that demonstrates nanoscale control for the recovery of uranium from simulated used nuclear fuel (SIMFUEL). The selective, hydrogen peroxide induced oxidative dissolution of SIMFUEL material results in the rapid assembly of persistent uranyl peroxide nanocluster species that can be separated and recovered at moderate to high yield from other process-soluble constituents using sequestration-assisted ultrafiltration. Implementation of size-selective physical processes like filtration could results in an overall simplification of nuclear fuel cycle technology, improving the environmental consequences of nuclear energy and reducing costs of processing. - Highlights: • Nanoscale control in irradiated fuel reprocessing. • Ultrafiltration to recover uranyl cage clusters. • Alternative to solvent extraction for uranium purification.

  12. Inherent wettability of different rock surfaces at nanoscale: a theoretical study

    Science.gov (United States)

    Chang, Xiao; Xue, Qingzhong; Li, Xiaofang; Zhang, Jianqiang; Zhu, Lei; He, Daliang; Zheng, Haixia; Lu, Shuangfang; Liu, Zilong

    2018-03-01

    Investigating the inherent wettability of rock surfaces at nanoscale is of great importance in ore floatation and oil recovery field. Using molecular dynamics simulations, we systematically study the wetting behavior of water on different rock surfaces (silica, calcite, gypsum, halite and graphite) at nanoscale. It is demonstrated that the inherent rock wettability follows the order of gypsum > calcite > halite > silica > graphite. Remarkably, we also manifest that the polarity of oil molecules can affect the water contact angles on silica surface. For example, the water contact angles on silica surface in hexane, dodecane, thiophene and toluene are 58 ± 2°, 63 ± 3°, 90 ± 1°, 118 ± 1°, respectively. Furthermore, we investigate the wetting behavior of water on heterogeneous rock surfaces and find that water molecules can move from hydrophobic surface to hydrophilic surface.

  13. Nanoscale characterization of isolated individual type I collagen fibrils: polarization and piezoelectricity.

    Science.gov (United States)

    Minary-Jolandan, Majid; Yu, Min-Feng

    2009-02-25

    Piezoresponse force microscopy was applied to directly study individual type I collagen fibrils with diameters of approximately 100 nm isolated from bovine Achilles tendon. It was revealed that single collagen fibrils behave predominantly as shear piezoelectric materials with a piezoelectric coefficient on the order of 1 pm V(-1), and have unipolar axial polarization throughout their entire length. It was estimated that, under reasonable shear load conditions, the fibrils were capable of generating an electric potential up to tens of millivolts. The result substantiates the nanoscale origin of piezoelectricity in bone and tendons, and implies also the potential importance of the shear load-transfer mechanism, which has been the principle basis of the nanoscale mechanics model of collagen, in mechanoelectric transduction in bone.

  14. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range

    Science.gov (United States)

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  15. Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

    Science.gov (United States)

    Juang, Jia-Yang; Zheng, Jinglin

    2016-10-01

    Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

  16. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range.

    Science.gov (United States)

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-04-13

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications.

  17. Morphological and structural characterization of PHBV/organoclay nanocomposites by small angle X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Carli, Larissa N., E-mail: lncarli@ucs.br [Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, 91501-970, RS (Brazil); Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Bianchi, Otavio, E-mail: obianchi@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Machado, Giovanna, E-mail: giovannamachado@uol.com.br [Centro de Tecnologias Estrategicas do Nordeste, Av. Prof. Luiz Freire, 01, Cidade Universitaria, Recife, 50740-540, PE (Brazil); Programa de Pos-Graduacao de Materiais, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Recife, 50670-901, PE (Brazil); Crespo, Janaina S., E-mail: jscrespo@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, Rua Francisco Getulio Vargas, 1130, Caxias do Sul, 95070-560, RS (Brazil); Mauler, Raquel S., E-mail: raquel.mauler@ufrgs.br [Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, 91501-970, RS (Brazil)

    2013-03-01

    In this work, the morphological and structural behaviors of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites were investigated using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The nanocomposites with 1, 3 and 5 wt.% of organically modified montmorillonite Cloisite Registered-Sign 30B (OMMT) were prepared by melt processing in a twin screw extruder using two different processing conditions (low and high shear intensity). The lamellar long period of the polymer was lower for the nanocomposites, with high polydispersity values. However, the crystalline thickness increased with the clay content and was independent of the processing conditions. This behavior resulted in a high linear crystallinity of the nanocomposites with 3 and 5 wt.% OMMT. The disruption factor ({beta}) was in agreement with the WAXD and TEM findings, indicating a good dispersion of the nanoparticles in the PHBV matrix with 3 wt.% of OMMT during the high shear intensity of melt processing. Highlights: Black-Right-Pointing-Pointer SAXS was used for morphological and crystalline studies of PHBV/OMMT nanocomposites. Black-Right-Pointing-Pointer The crystalline structure was influenced by the presence of clay. Black-Right-Pointing-Pointer The degree of clay dispersion in a polymer matrix was quantified. Black-Right-Pointing-Pointer The morphology comprised exfoliated particles, nanoscale and microscale clusters. Black-Right-Pointing-Pointer The results obtained by SAXS agreed well with TEM and WAXD results.

  18. Anomalous electromagnetic coupling via entanglement at the nanoscale

    International Nuclear Information System (INIS)

    Slepyan, Gregory; Boag, Amir; Mordachev, Vladimir; Sinkevich, Eugene; Maksimenko, Sergey; Kuzhir, Polina; Miano, Giovanni; Portnoi, Mikhail E; Maffucci, Antonio

    2017-01-01

    Understanding unwanted mutual interactions between devices at the nanoscale is crucial for the study of the electromagnetic compatibility in nanoelectronic and nanophotonic systems. Anomalous electromagnetic coupling (crosstalk) between nanodevices may arise from the combination of electromagnetic interaction and quantum entanglement. In this paper we study in detail the crosstalk between two identical nanodevices, each consisting of a quantum emitter (atom, quantum dot, etc), capacitively coupled to a pair of nanoelectrodes. Using the generalized susceptibility concept, the overall system is modeled as a two-port within the framework of the electrical circuit theory and it is characterized by the admittance matrix. We show that the entanglement changes dramatically the physical picture of the electromagnetic crosstalk. In particular, the excitation produced in one of the ports may be redistributed in equal parts between both the ports, in spite of the rather small electromagnetic interactions. Such an anomalous crosstalk is expected to appear at optical frequencies in lateral GaAs double quantum dots. A possible experimental set up is also discussed. The classical concepts of interference in the operation of electronic devices, which have been known since the early days of radio-communications and are associated with electromagnetic compatibility, should then be reconsidered at the nanoscale. (paper)

  19. Micro and Nano-Scale Technologies for Cell Mechanics

    Directory of Open Access Journals (Sweden)

    Mustafa Unal

    2014-10-01

    Full Text Available Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and micro and nanotechnology, which synergize to help us better understand the intricacies and the complex nature of cells in their native environment. With recent advances in nanotechnology, microfabrication methods and micro-electro-mechanical-systems (MEMS, we are now well situated to tap into the complex micro world of cells. The field that brings biology and MEMS together is known as Biological MEMS (BioMEMS. BioMEMS take advantage of systematic design and fabrication methods to create platforms that allow us to study cells like never before. These new technologies have been rapidly advancing the study of cell mechanics. This review article provides a succinct overview of cell mechanics and comprehensively surveys micro and nano-scale technologies that have been specifically developed for and are relevant to the mechanics of cells. Here we focus on micro and nano-scale technologies, and their applications in biology and medicine, including imaging, single cell analysis, cancer cell mechanics, organ-on-a-chip systems, pathogen detection, implantable devices, neuroscience and neurophysiology. We also provide a perspective on the future directions and challenges of technologies that relate to the mechanics of cells.

  20. Morphology and mechanical properties of PA12/plasticized starch blends prepared by high-shear extrusion

    International Nuclear Information System (INIS)

    Teyssandier, F.; Cassagnau, P.; Gérard, J.F.; Mignard, N.; Mélis, F.

    2012-01-01

    Highlights: ► High shear rate processing was found to greatly impact PA12/starch blend morphologies. ► The morphology was observed to be stable under subsequent processing conditions. ► The mechanical properties of the blends under high-shear rate were greatly improved. ► Polymer blend preparation via high-shear processing has proved to be very effective. ► Finally, polymer blends with improved mechanical properties were obtained. - Abstract: PA12/plasticized starch blends (PA12/TPS) were prepared by high-shear twin screw extruder. The morphology development and the mechanical properties of the blends were investigated as a function of the apparent shear rate. High-shear processing has proved to be an efficient method to finely disperse thermoplastic starch in polyamide 12 matrix. Blends containing TPS domains with a size at the nano-scale (R n ∼ 150 nm) homogeneously dispersed in PA12 matrix were obtained. From a modeling point of view, the variation of the droplet radius is closer to the Wu's predictions compared to the Serpe's predictions. From the basic hypothesis of these models, it can be then assumed that compatibilization between both phases occurs during the blend processing. Furthermore, this morphology of the blends has been proved to be stable after a reprocessing step in an internal mixer most likely due to either strong hydrogen bonds between the hydroxyl groups of starch and amide groups of polyamide 12 or to potentially cross reactions between macroradicals accounting for in situ formation of graft copolymers with the potential function of compatibilizers. Mechanical properties of the blends were found to be strongly dependent on the shear rate parameter of blend processing as the mechanical properties increase with shear rate. In agreement to the blend morphology, the elongation at break of the blends was greatly improved attesting of a good adhesion between both phases.

  1. Thorium oxalate solubility and morphology

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.; Hall, R.

    1981-10-01

    Thorium was used as a stand-in for studying the solubility and precipitation of neptunium and plutonium oxalates. Thorium oxalate solubility was determined over a range of 0.001 to 10.0 in the concentration parameter [H 2 C 2 O 4 ]/[HNO 3 ] 2 . Morphology of thorium oxide made from the oxalate precipitates was characterized by scanning electron microscopy. The different morphologies found for oxalate-lean and oxalate-rich precipitations were in agreement with predictions based on precipitation theory

  2. Towards Realization of Intelligent Medical Treatment at Nanoscale by Artificial Microscopic Swarm Control Systems

    Directory of Open Access Journals (Sweden)

    Alireza Rowhanimanesh

    2017-07-01

    Full Text Available Background: In this paper, the novel concept of artificial microscopic swarm control systems is proposed as a promising approach towards realization of intelligent medical treatment at nanoscale. In this new paradigm, treatment is done autonomously at nanoscale within the patient’s body by the proposed swarm control systems.Methods: From control engineering perspective, medical treatment can be considered as a control problem, in which the ultimate goal is to find the best feasible way to change the state of diseased tissue from unhealthy to healthy in presence of uncertainty. Although a living tissue is a huge swarm of microscopic cells, nearly all of the common treatment methods are based on macroscopic centralized control paradigm. Inspired by natural microscopic swarm control systems such as nervous, endocrine and immune systems that work based on swarm control paradigm, medical treatment needs a paradigm shift from macroscopic centralized control to microscopic swarm control. An artificial microscopic swarm control system consists of a huge number of very simple autonomous microscopic agents that exploit swarm intelligence to realize sense, control (computing and actuation at nanoscale in local, distributed and decentralized manner. This control system can be designed based on mathematical analysis and computer simulation.Results: The proposed approach is used for treatment of atherosclerosis and cancer based on mathematical analysis and in-silico study.Conclusion: The notion of artificial microscopic swarm control systems opens new doors towards realization of autonomous and intelligent medical treatment at nanoscale within the patient’s body.

  3. On the Morphology of the SDS Film on the Surface of Borosilicate Glass

    Directory of Open Access Journals (Sweden)

    Zih-Yao Shen

    2017-05-01

    Full Text Available Surfactant films on solid surfaces have attracted much attention because of their scientific interest and applications, such as surface treatment agent, or for micro- or nano-scale templates for microfluidic devices. In this study, anionic surfactant sodium dodecyl sulfate (SDS solutions with various charged inorganic salts was spread on a glass substrate and dried to form an SDS thin film. Atomic force microscopy (AFM was employed to observe the micro-structure of the SDS thin film. The effects of inorganic salts on the morphology of the SDS film were observed and discussed. The results of experiments demonstrated that pure SDS film formed patterns of long, parallel, highly-ordered stripes. The existence of the inorganic salt disturbed the structure of the SDS film due to the interaction between the cationic ion and the anionic head groups of SDS. The divalent ion has greater electrostatic interaction with anionic head groups than that of the monovalent ion, and causes a gross change in the morphology of the SDS film. The height of the SDS bilayer measured was consistent with the theoretical value, and the addition of the large-sized monovalent ion would lead to lowering the height of the adsorbed structures.

  4. Air-stable nZVI formation mediated by glutamic acid: solid-state storable material exhibiting 2D chain morphology and high reactivity in aqueous environment

    Science.gov (United States)

    Siskova, Karolina; Tucek, Jiri; Machala, Libor; Otyepkova, Eva; Filip, Jan; Safarova, Klara; Pechousek, Jiri; Zboril, Radek

    2012-03-01

    We report a new chemical approach toward air-stable nanoscale zero-valent iron (nZVI). The uniformly sized (approx. 80 nm) particles, formed by the reduction of Fe(II) salt by borohydride in the presence of glutamic acid, are coated by a thin inner shell of amorphous ferric oxide/hydroxide and a secondary shell consisting of glutamic acid. The as-prepared nanoparticles stabilized by the inorganic-organic double shell create 2D chain morphologies. They are storable for several months under ambient atmosphere without the loss of Fe(0) relative content. They show one order of magnitude higher rate constant for trichlorethene decomposition compared with the pristine particles possessing only the inorganic shell as a protective layer. This is the first example of the inorganic-organic (consisting of low-molecular weight species) double-shell stabilized nanoscale zero-valent iron material being safely transportable in solid-state, storable on long-term basis under ambient conditions, environmentally acceptable for in situ applications, and extraordinarily reactive if contacted with reducible pollutants, all in one.

  5. Design Optimization of Radionuclide Nano-Scale Batteries

    International Nuclear Information System (INIS)

    Schoenfeld, D.W.; Tulenko, J.S.; Wang, J.; Smith, B.

    2004-01-01

    Radioisotopes have been used for power sources in heart pacemakers and space applications dating back to the 50's. Two key properties of radioisotope power sources are high energy density and long half-life compared to chemical batteries. The tritium battery used in heart pacemakers exceeds 500 mW--hr, and is being evaluated by the University of Florida for feasibility as a MEMS (MicroElectroMechanical Systems) power source. Conversion of radioisotope sources into electrical power within the constraints of nano-scale dimensions requires cutting-edge technologies and novel approaches. Some advances evolving in the III-V and II-IV semiconductor families have led to a broader consideration of radioisotopes rather free of radiation damage limitations. Their properties can lead to novel battery configurations designed to convert externally located emissions from a highly radioactive environment. This paper presents results for the analytical computational assisted design and modeling of semiconductor prototype nano-scale radioisotope nuclear batteries from MCNP and EGS programs. The analysis evaluated proposed designs and was used to guide the selection of appropriate geometries, material properties, and specific activities to attain power requirements for the MEMS batteries. Plans utilizing high specific activity radioisotopes were assessed in the investigation of designs employing multiple conversion cells and graded junctions with varying band gap properties. Voltage increases sought by serial combination of VOC s are proposed to overcome some of the limitations of a low power density. The power density is directly dependent on the total active areas

  6. Mandibular condylar morphology for bruxers with different grinding patterns.

    Science.gov (United States)

    Tao, Jianxiang; Wu, Junhua; Zhang, Xuying

    2016-07-01

    The purpose of this study was to investigate the mandibular condylar morphology for bruxers with different grinding patterns. Condylar sectional morphology and condylar position of 30 subjects were determined by two viewers using cone beam computed tomography (CBCT) image data sets. The grinding patterns during sleep bruxism (SB) were determined objectively using a Brux-checker device.Chi-square tests were used for statistical analysis for the condylar morphology type between different tooth grinding patterns. Spearman's rank correlation coefficient was used for correlation analysis between condylar position and the canine guidance area during SB. Theincidence of condylarmorphologicaldivergence from idealwas35%.There isa significant difference in distribution of condylar morphology type between the group grinding (GG) and GG combined with mediotrusive side grinding (MG) (p < 0.05). There was no significant correlation between condylar position and canine guidance area during bruxism. MG during SB is associated with condylar morphology that is considered not to be ideal.

  7. Growth morphology of zinc tris(thiourea) sulphate crystals

    Indian Academy of Sciences (India)

    The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman–Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A computer code is developed for carrying out ...

  8. Comparison of Micro- and Nanoscale Fe+3-Containing (Hematite) Particles for Their Toxicological Properties in Human Lung Cells In Vitro

    NARCIS (Netherlands)

    Bhattacharya, K.; Hoffmann, E.; Schins, R.F.P.; Boertz, J.; Prantl, E.M.; Alink, G.M.; Byrne, H.J.; Kuhlbusch, T.A.J.; Rahman, Q.; Wiggers, H.; Schulz, C.; Dopp, E.

    2012-01-01

    The specific properties of nanoscale particles, large surface-to-mass ratios and highly reactive surfaces, have increased their commercial application in many fields. However, the same properties are also important for the interaction and bioaccumulation of the nonbiodegradable nanoscale particles

  9. Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

    KAUST Repository

    Kumar, Naresh; Zoladek-Lemanczyk, Alina; Guilbert, Anne A. Y.; Su, Weitao; Tuladhar, Sachetan M.; Kirchartz, Thomas; Schroeder, Bob C.; McCulloch, Iain; Nelson, Jenny; Roy, Debdulal; Castro, Fernando A.

    2017-01-01

    resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale

  10. Nanoscale elasticity mappings of micro-constituents of abalone shell by band excitation-contact resonance force microscopy

    Science.gov (United States)

    Li, Tao; Zeng, Kaiyang

    2014-01-01

    The macroscopic mechanical properties of the abalone shell have been studied extensively in the literature, but the in situ nanoscale elasticity of various micro-constituents in the shell have not been characterized and reported yet. In this study, the nanoscale elasticity mappings including different micro-constituents in abalone shell were observed by using the Contact Resonance Force Microscopy (CR-FM) technique. CR-FM is one of the advanced scanning probe microscopy techniques that is able to quantify the local elastic moduli of various materials in a non-destructive manner. Instead of an average value, an elasticity mapping that reveals the nanoscale variations of elastic moduli with location can be extracted and correlated with the topography of the structure. Therefore in this study, by adopting the CR-FM technique that is incorporated with the band excitation technique, the elasticity variations of the abalone shell caused by different micro-constituents and crystal orientations are reported, and the elasticity values of the aragonite and calcite nanograins are quantified.The macroscopic mechanical properties of the abalone shell have been studied extensively in the literature, but the in situ nanoscale elasticity of various micro-constituents in the shell have not been characterized and reported yet. In this study, the nanoscale elasticity mappings including different micro-constituents in abalone shell were observed by using the Contact Resonance Force Microscopy (CR-FM) technique. CR-FM is one of the advanced scanning probe microscopy techniques that is able to quantify the local elastic moduli of various materials in a non-destructive manner. Instead of an average value, an elasticity mapping that reveals the nanoscale variations of elastic moduli with location can be extracted and correlated with the topography of the structure. Therefore in this study, by adopting the CR-FM technique that is incorporated with the band excitation technique, the

  11. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi

    2014-11-11

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  12. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi; Park, Youngjune; Petit, Camille; Park, Ah-Hyung Alissa

    2014-01-01

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  13. Experimental study on tensile bifurcation of nanoscale Cu film bonded to polyethylene terephthalate substrate

    International Nuclear Information System (INIS)

    Men, Yutao; Wang, Shibin; Jia, Haikun; Wu, Zhiliang; Li, Linan; Zhang, Chunqiu

    2013-01-01

    Cu films are widely used in flexible electronic products. Tensile mechanical properties of the film determine product performance. In this paper, tensile experiments of sputtered Cu films on a polyethylene terephthalate (PET) substrate were carried out under an optical microscope. In the experiments, three changes took place under tension: uniform deformation, microcrack initiation and propagation, and microcrack saturation. The elastic modulus of the Cu film is 120 GPa and is independent of film thickness since the film is formed to be continuous in the nanoscale range. Film thickness is an important parameter to decide the tensile properties. The critical fracture strain, the interfacial bonding strength, and the crack spacing after saturation are related to film thickness. The critical strain and the interfacial bonding strength of the nanoscale Cu film tend to ascend then to descend as film thickness increases. The microcrack spacing is in direct proportion to film thickness after the microcrack saturates. The optimum thickness of the sputtered Cu films on the PET substrate is about 500 nm. - Highlights: • The elastic modulus of the Cu films is 120 GPa and does not change with thickness. • The optimal thickness of the Cu films is about 500 nm. • The critical strain tends to ascend then to descend as film thickness increases. • The interfacial strength changes in accordance with the critical strain. • Microcrack spacing is proportional to film thickness after the microcrack saturates

  14. Nanoscale size effect in in situ titanium based composites with cell viability and cytocompatibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Miklaszewski, Andrzej, E-mail: andrzej.miklaszewski@put.poznan.pl [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland); Jurczyk, Mieczysława U. [Division Mother' s and Child' s Health, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Kaczmarek, Mariusz [Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Paszel-Jaworska, Anna; Romaniuk, Aleksandra; Lipińska, Natalia [Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, Przybyszewskiego 49, 60-355 Poznan (Poland); Żurawski, Jakub [Department of Immunobiochemistry, Chair of Biology and Environmental Sciences, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznan (Poland); Urbaniak, Paulina [Department of Cell Biology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Jurczyk, Mieczyslaw [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland)

    2017-04-01

    Novel in situ Metal Matrix Nanocomposite (MMNC) materials based on titanium and boron, revealed their new properties in the nanoscale range. In situ nanocomposites, obtained through mechanical alloying and traditional powder metallurgy compaction and sintering, show obvious differences to their microstructural analogue. A unique microstructure connected with good mechanical properties reliant on the processing conditions favour the nanoscale range of results of the Ti-TiB in situ MMNC example. The data summarised in this work, support and extend the knowledge boundaries of the nanoscale size effect that influence not only the mechanical properties but also the studies on the cell viability and cytocompatibility. Prepared in the same bulk, in situ MMNC, based on titanium and boron, could be considered as a possible candidate for dental implants and other medical applications. The observed relations and research conclusions are transferable to the in situ MMNC material group. Aside from all the discussed relations, the increasing share of these composites in the ever-growing material markets, heavily depends on the attractiveness and a possible wider application of these composites as well as their operational simplicity presented in this work. - Highlights: • Nano and microscale size precursor influence the final composite microstructure and properties. • Obtained from the nanoscale precursor sinters, characterise with a uniform and highly dispersed microstructure • Mechanical properties favoured Nano scale size precursor • Boron addition could be significantly reduced for moderate properties range. • A possible candidate for dental implants and other medical applications.

  15. Friction and Surface Dynamics of Polymers on the Nanoscale by AFM

    NARCIS (Netherlands)

    Schönherr, Holger; Schónherr, Holger; Samori, Paolo; Tocha, E.; Vancso, Gyula J.

    2008-01-01

    In this article the measurement and understanding of friction forces and surface dynamics of polymers on the one hand and the importance of molecular relaxation processes and viscoelasticity in polymers for advanced micro- and nanoscale applications on the other hand are discussed. Particular

  16. In-situ Liquid Electron Microscopy Setups for Investigation of Nanoscale Electrochemistry

    DEFF Research Database (Denmark)

    Jensen, Eric; Møller-Nilsen, Rolf Erling Robberstad; Canepa, Silvia

    2014-01-01

    -situ electrochemistry and has achieved ~10 nm resolution. Such systems are important tools for developing sustainable technology and for understanding nanoscale phenomena. However, both systems suffer from interacting with theelectron beam, which is a high-voltage radiation source, and therefore initial experiments...

  17. 75 FR 30874 - National Nanotechnology Coordination Office, Nanoscale Science, Engineering and Technology...

    Science.gov (United States)

    2010-06-02

    ... OFFICE OF SCIENCE AND TECHNOLOGY POLICY National Nanotechnology Coordination Office, Nanoscale Science, Engineering and Technology Subcommittee, National Science and Technology Council, Committee on Technology; The National Nanotechnology Initiative (NNI) Strategic Planning Stakeholder Workshop: Public...

  18. Interfibrillar stiffening of echinoderm mutable collagenous tissue demonstrated at the nanoscale.

    Science.gov (United States)

    Mo, Jingyi; Prévost, Sylvain F; Blowes, Liisa M; Egertová, Michaela; Terrill, Nicholas J; Wang, Wen; Elphick, Maurice R; Gupta, Himadri S

    2016-10-18

    The mutable collagenous tissue (MCT) of echinoderms (e.g., sea cucumbers and starfish) is a remarkable example of a biological material that has the unique attribute, among collagenous tissues, of being able to rapidly change its stiffness and extensibility under neural control. However, the mechanisms of MCT have not been characterized at the nanoscale. Using synchrotron small-angle X-ray diffraction to probe time-dependent changes in fibrillar structure during in situ tensile testing of sea cucumber dermis, we investigate the ultrastructural mechanics of MCT by measuring fibril strain at different chemically induced mechanical states. By measuring a variable interfibrillar stiffness (E IF ), the mechanism of mutability at the nanoscale can be demonstrated directly. A model of stiffness modulation via enhanced fibrillar recruitment is developed to explain the biophysical mechanisms of MCT. Understanding the mechanisms of MCT quantitatively may have applications in development of new types of mechanically tunable biomaterials.

  19. Controllable nanoscale rotating actuator system based on carbon nanotube and graphene

    International Nuclear Information System (INIS)

    Huang, Jianzhang; Han, Qiang

    2016-01-01

    A controllable nanoscale rotating actuator system consisting of a double carbon nanotube and graphene driven by a temperature gradient is proposed, and its rotating dynamics performance and driving mechanism are investigated through molecular dynamics simulations. The outer tube exhibits stable pure rotation with certain orientation under temperature gradient and the steady rotational speed rises as the temperature gradient increases. It reveals that the driving torque is caused by the difference of atomic van der Waals potentials due to the temperature gradient and geometrical features of carbon nanotube. A theoretical model for driving torque is established based on lattice dynamics theory and its predicted results agree well with molecular dynamics simulations. Further discussion is taken according to the theoretical model. The work in this study would be a guide for design and application of controllable nanoscale rotating devices based on carbon nanotubes and graphene. (paper)

  20. Local biochemical and morphological differences in human Achilles tendinopathy

    DEFF Research Database (Denmark)

    Pingel, Jessica; Fredberg, U.; Qvortrup, Klaus

    2012-01-01

    The incidence of Achilles tendinopathy is high and underlying etiology as well as biochemical and morphological pathology associated with the disease is largely unknown. The aim of the present study was to describe biochemical and morphological differences in chronic Achilles tendinopathy....... The expressions of growth factors, inflammatory mediators and tendon morphology were determined in both chronically diseased and healthy tendon parts....

  1. Observed gas hydrate morphologies in marine sediment

    Energy Technology Data Exchange (ETDEWEB)

    Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)

    2008-07-01

    The morphology of gas hydrate in marine sediments determines the basic physical properties of the sediment-hydrate matrix and provides information regarding the formation of gas hydrate deposits, and the nature of the disruption that will occur on dissociation. Small-scale morphology is useful in estimating the concentrations of gas hydrate from geophysical data. It is also important for predicting their response to climate change or commercial production. Many remote techniques for gas hydrate detection and quantification depend on hydrate morphology. In this study, morphology of gas hydrate was examined in HYACINTH pressure cores from recent seagoing expeditions. Visual and infrared observations from non-pressurized cores were also used. The expeditions and pressure core analysis were described in detail. This paper described the difference between two types of gas hydrate morphologies, notably pore-filling and grain-displacing. Last, the paper addressed the impact of hydrate morphology. It was concluded that a detailed morphology of gas hydrate is an essential component for a full understanding of the past, present, and future of any gas hydrate environment. 14 refs., 4 figs.

  2. Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

    Science.gov (United States)

    Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

    2017-02-28

    Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

  3. Nano-Scale Interpenetrating Phase Composites (IPC S) for Industrial and Vehicle Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James Gordon [ORNL; Hu, Michael Z. [ORNL

    2010-06-01

    A one-year project was completed at Oak Ridge National Laboratory (ORNL) to explore the technical and economic feasibility of producing nano-scale Interpenetrating Phase Composite (IPC) components of a usable size for actual testing/implementation in a real applications such as high wear/corrosion resistant refractory shapes for industrial applications, lightweight vehicle braking system components, or lower cost/higher performance military body and vehicle armor. Nano-scale IPC s with improved mechanical, electrical, and thermal properties have previously been demonstrated at the lab scale, but have been limited in size. The work performed under this project was focused on investigating the ability to take the current traditional lab scale processes to a manufacturing scale through scaling of these processes or through the utilization of an alternative high-temperature process.

  4. Retention and failure morphology of prefabricated posts

    DEFF Research Database (Denmark)

    Sahafi, Alireza; Peutzfeldt, Anne; Asmussen, Erik

    2004-01-01

    PURPOSE: This study evaluated the effect of cement, post material, surface treatment, and shape (1) on the retention of posts luted in the root canals of extracted human teeth and (2) on the failure morphology. MATERIALS AND METHODS: Posts of titanium alloy (ParaPost XH), glass fiber (Para...... at 37 degrees C for 7 days, retention was determined by extraction of the posts. Failure morphology of extracted posts was analyzed and quantified stereomicroscopically. RESULTS: Type of luting cement, post material, and shape of post influenced the retention and failure morphology of the posts. Because...

  5. Probing defect and magnetic structures on the nanoscale

    OpenAIRE

    Kallis, Alexis

    2010-01-01

    This thesis reports on experimental research on structural defects and magnetic species on the nanoscale. The latter project involved considerable development work on the production of a spin-polarised mono-energetic positron beam. The construction of the system is described through various trial steps with emphasis on the methods of maximum practical polarization of the positron beam and of electrons in the sample with the smallest possible loss of beam intensity. A new sodium-22 source caps...

  6. Interplay of Peltier and Seebeck Effects in Nanoscale Nonlocal Spin Valves

    NARCIS (Netherlands)

    Bakker, F. L.; Slachter, A.; Adam, J-P; van Wees, B. J.

    2010-01-01

    We have experimentally studied the role of thermoelectric effects in nanoscale nonlocal spin valve devices. A finite element thermoelectric model is developed to calculate the generated Seebeck voltages due to Peltier and Joule heating in the devices. By measuring the first, second, and third

  7. In-situ realtime monitoring of nanoscale gold electroplating using micro-electro-mechanical systems liquid cell operating in transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Egawa, Minoru; Fujita, Hiroyuki [Institute of Industrial Science, University of Tokyo, Meguro, Tokyo 153-8505 (Japan); Ishida, Tadashi, E-mail: ishida.t.ai@m.titech.ac.jp [Institute of Industrial Science, University of Tokyo, Meguro, Tokyo 153-8505 (Japan); Graduate School of Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa 225-8503 (Japan); Jalabert, Laurent [LIMMS/CNRS-IIS (UMI 2820), Institute of Industrial Science, University of Tokyo, Meguro, Tokyo 153-8505 (Japan); CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse, France and University of Toulouse, LAAS, F-31400 Toulouse (France)

    2016-01-11

    The dynamics of nanoscale electroplating between gold electrodes was investigated using a microfabricated liquid cell mounted on a scanning transmission electron microscope. The electroplating was recorded in-situ for 10 min with a spatial resolution higher than 6 nm. At the beginning of the electroplating, gold spike-like structures of about 50 nm in size grew from an electrode, connected gold nanoclusters around them, and form three dimensional nanoscale structures. We visualized the elementary process of the gold electroplating, and believe that the results lead to the deeper understanding of electroplating at the nanoscale.

  8. In-situ realtime monitoring of nanoscale gold electroplating using micro-electro-mechanical systems liquid cell operating in transmission electron microscopy

    International Nuclear Information System (INIS)

    Egawa, Minoru; Fujita, Hiroyuki; Ishida, Tadashi; Jalabert, Laurent

    2016-01-01

    The dynamics of nanoscale electroplating between gold electrodes was investigated using a microfabricated liquid cell mounted on a scanning transmission electron microscope. The electroplating was recorded in-situ for 10 min with a spatial resolution higher than 6 nm. At the beginning of the electroplating, gold spike-like structures of about 50 nm in size grew from an electrode, connected gold nanoclusters around them, and form three dimensional nanoscale structures. We visualized the elementary process of the gold electroplating, and believe that the results lead to the deeper understanding of electroplating at the nanoscale

  9. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    Science.gov (United States)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  10. Strengthening effect of nano-scale precipitates in a die-cast Mg–4Al–5.6Sm–0.3Mn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qiang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Bu, Fanqiang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Qiu, Xin [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yangzhou Hongfu Aluminium Co. Ltd, Yangzhou 100049 (China); Li, Yangde; Li, Weirong [E-ande Scientific & Technology Co. Ltd, Dongguan 523000 (China); Sun, Wei [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Liu, Xiaojuan, E-mail: lxjuan@ciac.ac.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng, Jian, E-mail: jmeng@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2016-04-25

    In this paper we report a quantitative study of the age-hardening in the high-pressure die-cast Mg–4Al−5.6Sm−0.3Mn alloy. The results indicate that a number of nano-scale spherical precipitates identified as Al{sub 3}Sm using high-angle annular dark-field scanning transmission electron microscopy, precipitated in Mg matrix after aging at 150–225 °C, with no obvious changes on grain sizes, intermetallic phases formed during solidification, and dislocation densities. From the existing strengthening theory equations in which some lacking parameters were taken from the first-principles density functional theory (DFT) calculations, a quantitative insight into the strengthening mechanisms of the nano-scale precipitate was formulated. The results are in reasonable agreement with the experimental values, and the operative mechanism of precipitation strengthening was revealed as Orowan dislocation bypassing. - Highlights: • The yield strength of Mg–Al–Sm alloy was improved by aging treatment. • A number of nano-scale precipitates formed in matrix after aging treatments. • The nanoscale precipitate was confirmed as Al{sub 3}Sm based on the data of HAADF-STEM study. • The strengthening mechanisms of the nano-scale precipitate were quantitatively formulated. • The operative mechanism of precipitate strengthening is Orowan dislocation bypassing.

  11. On the relationship between the dynamic behavior and nanoscale staggered structure of the bone

    Science.gov (United States)

    Qwamizadeh, Mahan; Zhang, Zuoqi; Zhou, Kun; Zhang, Yong Wei

    2015-05-01

    Bone, a typical load-bearing biological material, composed of ordinary base materials such as organic protein and inorganic mineral arranged in a hierarchical architecture, exhibits extraordinary mechanical properties. Up to now, most of previous studies focused on its mechanical properties under static loading. However, failure of the bone occurs often under dynamic loading. An interesting question is: Are the structural sizes and layouts of the bone related or even adapted to the functionalities demanded by its dynamic performance? In the present work, systematic finite element analysis was performed on the dynamic response of nanoscale bone structures under dynamic loading. It was found that for a fixed mineral volume fraction and unit cell area, there exists a nanoscale staggered structure at some specific feature size and layout which exhibits the fastest attenuation of stress waves. Remarkably, these specific feature sizes and layouts are in excellent agreement with those experimentally observed in the bone at the same scale, indicating that the structural size and layout of the bone at the nanoscale are evolutionarily adapted to its dynamic behavior. The present work points out the importance of dynamic effect on the biological evolution of load-bearing biological materials.

  12. Overview of nanoscale NEXAFS performed with soft X-ray microscopes

    Directory of Open Access Journals (Sweden)

    Peter Guttmann

    2015-02-01

    Full Text Available Today, in material science nanoscale structures are becoming more and more important. Not only for the further miniaturization of semiconductor devices like carbon nanotube based transistors, but also for newly developed efficient energy storage devices, gas sensors or catalytic systems nanoscale and functionalized materials have to be analysed. Therefore, analytical tools like near-edge X-ray absorption fine structure (NEXAFS spectroscopy has to be applied on single nanostructures. Scanning transmission X-ray microscopes (STXM as well as full-field transmission X-ray microscopes (TXM allow the required spatial resolution to study individual nanostructures. In the soft X-ray energy range only STXM was used so far for NEXAFS studies. Due to its unique setup, the TXM operated by the Helmholtz-Zentrum Berlin (HZB at the electron storage ring BESSY II is the first one in the soft X-ray range which can be used for NEXAFS spectroscopy studies which will be shown in this review. Here we will give an overview of the different microscopes used for NEXAFS studies and describe their advantages and disadvantages for different samples.

  13. Overview of nanoscale NEXAFS performed with soft X-ray microscopes.

    Science.gov (United States)

    Guttmann, Peter; Bittencourt, Carla

    2015-01-01

    Today, in material science nanoscale structures are becoming more and more important. Not only for the further miniaturization of semiconductor devices like carbon nanotube based transistors, but also for newly developed efficient energy storage devices, gas sensors or catalytic systems nanoscale and functionalized materials have to be analysed. Therefore, analytical tools like near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has to be applied on single nanostructures. Scanning transmission X-ray microscopes (STXM) as well as full-field transmission X-ray microscopes (TXM) allow the required spatial resolution to study individual nanostructures. In the soft X-ray energy range only STXM was used so far for NEXAFS studies. Due to its unique setup, the TXM operated by the Helmholtz-Zentrum Berlin (HZB) at the electron storage ring BESSY II is the first one in the soft X-ray range which can be used for NEXAFS spectroscopy studies which will be shown in this review. Here we will give an overview of the different microscopes used for NEXAFS studies and describe their advantages and disadvantages for different samples.

  14. Dynamics, Miscibility, and Morphology in Polymer-Molecule Blends: The Impact of Chemical Functionality

    KAUST Repository

    Do, Khanh

    2015-10-22

    In the quest to improve the performance of organic bulk-heterojunction solar cells, many recent efforts have focused on developing molecular and polymer alternatives to commonly used fullerene acceptors. Here, molecular dynamics simulations are used to investigate polymer-molecule blends comprised of the polymer donor poly(3-hexylthiophene) (P3HT) with a series of acceptors based on trialkylsilylethynyl-substituted pentacene. A matrix of nine pentacene derivatives, consisting of systematic chemical variation both in the nature of the alkyl groups and electron-withdrawing moieties appended to the acene, is used to draw connections between the chemical structure of the acene acceptor and the nanoscale properties of the polymer-molecule blend. These connections include polymer and molecular diffusivity, donor-acceptor packing and interfacial (contact) area, and miscibility. The results point to the very significant role that seemingly modest changes in chemical structure play during the formation of polymer-molecule blend morphologies.

  15. Dynamics, Miscibility, and Morphology in Polymer-Molecule Blends: The Impact of Chemical Functionality

    KAUST Repository

    Do, Khanh; Risko, Chad; Anthony, John E; Amassian, Aram; Bredas, Jean-Luc

    2015-01-01

    In the quest to improve the performance of organic bulk-heterojunction solar cells, many recent efforts have focused on developing molecular and polymer alternatives to commonly used fullerene acceptors. Here, molecular dynamics simulations are used to investigate polymer-molecule blends comprised of the polymer donor poly(3-hexylthiophene) (P3HT) with a series of acceptors based on trialkylsilylethynyl-substituted pentacene. A matrix of nine pentacene derivatives, consisting of systematic chemical variation both in the nature of the alkyl groups and electron-withdrawing moieties appended to the acene, is used to draw connections between the chemical structure of the acene acceptor and the nanoscale properties of the polymer-molecule blend. These connections include polymer and molecular diffusivity, donor-acceptor packing and interfacial (contact) area, and miscibility. The results point to the very significant role that seemingly modest changes in chemical structure play during the formation of polymer-molecule blend morphologies.

  16. Morphological changes in textile fibres exposed to environmental stresses: atomic force microscopic examination.

    Science.gov (United States)

    Canetta, Elisabetta; Montiel, Kimberley; Adya, Ashok K

    2009-10-30

    The ability of the atomic force microscope (AFM) to investigate the nanoscopic morphological changes in the surfaces of fabrics was examined for the first time. This study focussed on two natural (cotton and wool), and a regenerated cellulose (viscose) textile fibres exposed to various environmental stresses for different lengths of times. Analyses of the AFM images allowed us to measure quantitatively the surface texture parameters of the environmentally stressed fabrics as a function of the exposure time. It was also possible to visualise at the nanoscale the finest details of the surfaces of three weathered fabrics and clearly distinguish between the detrimental effects of the imposed environmental conditions. This study confirmed that the AFM could become a very powerful tool in forensic examination of textile fibres to provide significant fibre evidence due to its capability of distinguishing between different environmental exposures or forced damages to fibres.

  17. EDITORIAL: Mastering matter at the nanoscale Mastering matter at the nanoscale

    Science.gov (United States)

    Forchel, Alfred

    2009-10-01

    In the early 1980s, the development of scanning probe techniques gave scientists a titillating view of surfaces with nanometre resolution, igniting activity in research at the nanoscale. Images at unprecedented resolution were unveiled with the aid of various types of nanosized tips, including the scanning tunnelling (Binnig G, Rohrer H, Gerber C and Weibel E 1982 Appl. Phys. Lett. 40 178-80) the atomic force (Binnig G, Quate C F and Gerber C 1986 Phys. Rev. Lett. 56 930-3) and the near-field scanning microscopes (Dürig U, Pohl D W and Rohner F 1986 J. Appl. Phys. 59 3318-27). From the magnitude of tunnelling currents between conductive surfaces and van der Waals forces between dielectrics to the non-propagating evanescent fields at illuminated surfaces, a range of signal responses were harnessed enabling conductive, dielectric and even biological systems to be imaged. But it may be argued that it was the ability to manipulate matter at the nanoscale that really empowered nanotechnology. From the inception of the scanning probe revolution, these probes used to image nanostructures were also discovered to be remarkable tools for the manipulation of nanoparticles. Insights into the mechanism behind such processes were reported by a team of researchers at UCLA over ten years ago in 1998 (Baur C et al 1998 Nanotechnology 9 360-4). In addition, lithography and etching methods of patterning continue to evolve into ever more sophisticated techniques for exerting design over the structure of matter at the nanoscale. These so-called top-down methods, such as photolithography, electron-beam lithography and nanoimprint lithography, now provide control over features with a resolution of a few nanometres. Bottom-up fabrication techniques that exploit the self-assembly of constituents into desired structures have also stimulated extensive research. These techniques, such as the electrochemically assembled quantum-dot arrays reported by a team of US reasearchers over ten years

  18. Non-oxidic nanoscale composites: single-crystalline titanium carbide nanocubes in hierarchical porous carbon monoliths.

    Science.gov (United States)

    Sonnenburg, Kirstin; Smarsly, Bernd M; Brezesinski, Torsten

    2009-05-07

    We report the preparation of nanoscale carbon-titanium carbide composites with carbide contents of up to 80 wt%. The synthesis yields single-crystalline TiC nanocubes 20-30 nm in diameter embedded in a hierarchical porous carbon matrix. These composites were generated in the form of cylindrical monoliths but can be produced in various shapes using modern sol-gel and nanocasting methods in conjunction with carbothermal reduction. The monolithic material is characterized by a combination of microscopy, diffraction and physisorption. Overall, the results presented in this work represent a concrete design template for the synthesis of non-oxidic nanoscale composites with high surface areas.

  19. Deterministic assembly of linear gold nanorod chains as a platform for nanoscale applications

    DEFF Research Database (Denmark)

    Rey, Antje; Billardon, Guillaume; Loertscher, Emanuel

    2013-01-01

    target substrate, thus establishing a platform for a variety of nanoscale electronic and optical applications ranging from molecular electronics to optical and plasmonic devices. As a first example, electrical measurements are performed on contacted gold nanorod chains before and after their immersion......We demonstrate a method to assemble gold nanorods highly deterministically into a chain formation by means of directed capillary assembly. This way we achieved straight chains consisting of end-to-end aligned gold nanorods assembled in one specific direction with well-controlled gaps of similar...... to 6 nm between the individual constituents. We determined the conditions for optimum quality and yield of nanorod chain assembly by investigating the influence of template dimensions and assembly temperature. In addition, we transferred the gold nanorod chains from the assembly template onto a Si/SiO2...

  20. Low Dose X-Ray Speckle Visibility Spectroscopy Reveals Nanoscale Dynamics in Radiation Sensitive Ionic Liquids

    Science.gov (United States)

    Verwohlt, Jan; Reiser, Mario; Randolph, Lisa; Matic, Aleksandar; Medina, Luis Aguilera; Madsen, Anders; Sprung, Michael; Zozulya, Alexey; Gutt, Christian

    2018-04-01

    X-ray radiation damage provides a serious bottleneck for investigating microsecond to second dynamics on nanometer length scales employing x-ray photon correlation spectroscopy. This limitation hinders the investigation of real time dynamics in most soft matter and biological materials which can tolerate only x-ray doses of kGy and below. Here, we show that this bottleneck can be overcome by low dose x-ray speckle visibility spectroscopy. Employing x-ray doses of 22-438 kGy and analyzing the sparse speckle pattern of count rates as low as 6.7 ×10-3 per pixel, we follow the slow nanoscale dynamics of an ionic liquid (IL) at the glass transition. At the prepeak of nanoscale order in the IL, we observe complex dynamics upon approaching the glass transition temperature TG with a freezing in of the alpha relaxation and a multitude of millisecond local relaxations existing well below TG . We identify this fast relaxation as being responsible for the increasing development of nanoscale order observed in ILs at temperatures below TG .