Sample records for nanoscale multilayer pvd

  1. Tribological and mechanical properties of Ti/TiAlN/TiAlCN nanoscale multilayer PVD coatings deposited on AISI H11 hot work tool steel

    NASA Astrophysics Data System (ADS)

    AL-Bukhaiti, M. A.; Al-hatab, K. A.; Tillmann, W.; Hoffmann, F.; Sprute, T.

    2014-11-01

    A new [Ti/TiAlN/TiAlCN]5 multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al2O3 balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10 N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10-15 m3/N m, low friction coefficients against 100Cr6 and Al2O3 balls in the range of 0.25-0.37, and good hardness in the range of 17-20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al2O3 and coating/100Cr6 sliding system. Compared with the uncoated-H11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al2O3 pair, while for coating/100Cr6 pair, a combination of mild adhesive wear, severe adhesive wear, and abrasive wear (extensive plowing) were the dominant wear mechanisms at different applied normal loads.

  2. Characterization of multilayer pvd nanocoatings deposited on tungsten carbide cutting tools

    Microsoft Academic Search

    C. H. R. Vikram Kumar; P. Kesavan Nair; B. Ramamoorthy

    2008-01-01

    The present trends in the coating technologies are gradient coatings, metastable coatings, multicomponaent coatings and multilayer\\u000a or super lattice coatings. The physical vapour deposition (PVD) process is well-suited technology for these advanced coating\\u000a technologies. The performance of the coated tools can be improved considerably using multi-layer micro and nanocoatings. The\\u000a present paper discusses the deposition and characterization of multilayer TiN\\/Al2O3

  3. Characterisation of tribocorrosion behaviour of multilayer PVD coatings.

    PubMed

    Bayón, R; Nevshupa, R; Zubizarreta, C; Ruiz de Gopegui, U; Barriga, J; Igartua, A

    2010-04-01

    The effect of repassivation on tribocorrosion behaviour of two multilayer coatings of different structures is studied experimentally by measuring the variation of instantaneous open-circuit potential during friction. One coating consists of alternating Cr and CrN layers, while another consists of alternated layers of CrN and ZrN. Analysis of the results showed that friction force, i.e. the rate of the mechanical energy supplied to the material in the contact zone, has no direct influence on the tribocorrosion behaviour; however, the wear rate does strongly influence the tribocorrosion. A simple phenomenological model of repassivation of the multilayer coating is developed assuming "surface coverage" approach. This model establishes the relationship between the rate of mechanical activation of material by friction and the behaviour of the open-circuit potential. PMID:20204333

  4. Nanoindentation of Nanoscale Ti/Au Multilayer Benjamin Revard and David Bahr

    E-print Network

    Collins, Gary S.

    Nanoindentation of Nanoscale Ti/Au Multilayer Composites Benjamin Revard and David Bahr School of Mechanical and Materials Engineering, Washington State University Introduction Nanoscale metallic multilayer potential applications as nanoscale engineering materials, including applications in the semiconductor

  5. Yield maps for nanoscale metallic multilayers Adrienne V. Lamm *, Peter M. Anderson

    E-print Network

    Anderson, Peter M.

    Yield maps for nanoscale metallic multilayers Adrienne V. Lamm *, Peter M. Anderson Department for the macroscopic, in-plane, bi-axial tension to macroscopically yield a nanoscale multilayered thin film consisting mismatch on the macroscopic yield strength of metallic multilayer thin films. This will be accomplished

  6. Fabrication and nanoscale characterization of magnetic multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Elawayeb, Mohamed

    Magnetic multilayers nanowires are scientifically fascinating and have potential industrial applications in many areas of advanced nanotechnology. These applications arise due to the nanoscale dimensions of nanostructures that lead to unique physical properties. Magnetic multilayer nanowires have been successfully produced by electrodeposition into templates. Anodic Aluminium Oxide (AAO) membranes were used as templates in this process; the templates were fabricated by anodization method in acidic solutions at a fixed voltage. The fabrication method of a range of magnetic multilayer nanowires is described in this study and their structure and dimensions were analyzed using scanning electron microscope (SEM), Transmission electron microscope (TEM) and scanning transmission electron microscopy (STEM). This study is focused on the first growth of NiFe/Pt and NiFe/Fe magnetic multilayer nanowires, which were successfully fabricated by pulse electrodeposition into the channels of porous anodic aluminium oxide (AAO) templates, and characterized at the nanoscale. Individual nanowires have uniform structure and regular periodicity. The magnetic and nonmagnetic layers are polycrystalline, with randomly oriented fcc lattice structure crystallites. Chemical compositions of the individual nanowires were analyzed using TEM equipped with energy-dispersive x-ray analysis (EDX) and electron energy loss spectrometry (EELS). The electrical and magnetoresistance properties of individual magnetic multilayer nanowires have been measured inside a SEM using two sharp tip electrodes attached to in situ nanomanipulators and a new electromagnet technique. The giant magnetoresistance (GMR) effect of individual magnetic multilayer nanowires was measured in the current - perpendicular to the plane (CPP) geometry using a new in situ method at variable magnetic field strength and different orientations..

  7. PACVD TiN\\/Ti–B–N multilayers: from micro- to nano-scale

    Microsoft Academic Search

    M. Stoiber; S. Perlot; C. Mitterer; M. Beschliesser; C. Lugmair; R. Kullmer

    2004-01-01

    Multilayer coatings with compositionally modulated structures in the nanometer range such as superlattices often show improved mechanical properties compared to homogenous materials. Various physical vapor deposition (PVD) methods have been utilized to deposit superlattice coatings, while chemical vapor deposition (CVD) is not suitable due to interdiffusion at high deposition temperatures. The aim of this work was to investigate the potential

  8. Deposition, characterization and machining performance of multilayer PVD coatings on cemented carbide cutting tools

    Microsoft Academic Search

    C Ducros; V Benevent; F Sanchette

    2003-01-01

    CrN\\/TiN and TiN\\/AlTiN multilayer coatings with different periods were deposited on cemented carbide cutting tools in an industrial-size cathodic arc evaporation device. Nanolayer coatings were particularly studied and the influence of the superlattice period on mechanical behaviors have been investigated. Mechanical properties were first correlated to the period of multilayer and nanolayer coatings. Machining performance of coated cutting tools were

  9. Nano-multilayered self-adaptive hard PVD coatings for dry high performance machining

    Microsoft Academic Search

    Li Ning

    2008-01-01

    In this research, quaternary nitride nano-multilayered coatings of the form TiAlCrN\\/MexN were comprehensively characterized. Based on this research principles which can be applied for guiding coating design were developed using the concept of self-adaptability.^ Comprehensive studies were performed on the following aspects: the tribological properties of the coatings at elevated temperatures, tool life, and cutting forces, tribe-oxide formation, wear mechanisms

  10. Deformation-induced nanoscale mixing reactions in Cu/Ni and Ag/Pd multilayers

    SciTech Connect

    Wang, Z.; Perepezko, J. H., E-mail: perepezk@engr.wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, Wisconsin 53706 (United States)

    2013-11-04

    During the repeated cold rolling of Cu/Ni and Ag/Pd multilayers, a solid solution forms at the interfaces as nanoscale layer structure with a composition that replicates the overall multilayer composition. The interfacial mixing behavior was investigated by means of X-ray diffraction and scanning transmission electron microscopy. During deformation induced reaction, the intermixing behavior of the Cu/Ni and Ag/Pd multilayers is in contrast to thermally activated diffusion behavior. This distinct behavior can provide new kinetic pathways and offer opportunities for microstructure control that cannot be achieved by thermal processing.

  11. Biomaterials 26 (2005) 68366845 Tuning compliance of nanoscale polyelectrolyte multilayers to

    E-print Network

    Van Vliet, Krystyn J.

    Biomaterials 26 (2005) 6836­6845 Tuning compliance of nanoscale polyelectrolyte multilayers cause smooth muscle cells to secrete bone minerals typically produced by ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials

  12. Bilayer period dependence of CrN/CrAlN nanoscale multilayer thin films

    NASA Astrophysics Data System (ADS)

    Kim, Youn J.; Byun, Tae J.; Han, Jeon G.

    2009-02-01

    CrN/CrAlN nanoscale multilayer thin films with a bilayer period ( ?) ranging from 4.4 to 44.1 nm were deposited on Si wafers (100) by closed field unbalanced magnetron sputtering (CFUBMS). The ? of the layers was controlled by the rotation speed of the substrate holder. The coatings were characterized by high resolution X-ray diffraction and field emission transmission electron microscopy. The CrN/CrAlN nanoscale multilayer thin films exhibited a CrN (200) and AlN (200) crystalline orientation. Nano-indentation testing revealed a hardness ranging from 37 to 46 GPa according to the bilayer period. The highest hardness was obtained with a bilayer period of 5.5 nm due to the high resistance to plastic deformation.

  13. Nanoscale Texture Control of Polyelectrolyte Multilayer Using Spray Layer-by-Layer Method

    NASA Astrophysics Data System (ADS)

    Kyung, Kyu-Hong; Shiratori, Seimei

    2011-02-01

    Weak polyelectrolyte multilayer thin films deposited by sequential spraying of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) solutions are described. Using the spray layer-by-layer (spray-LBL) method, nanoscale texture structures were fabricated considering several factors such as the concentration of spray solution, spray quantity, and the flow rate of spray solution. It was also found that the formation of nanoscale texture structures was dependent on all three factors. Then, their surface morphologies were characterized. The surface morphologies of the fabricated films were observed by field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The FE-SEM and AFM images showed that using the spray-LBL method, the surface morphology can be controlled with nanometer-order accuracy. As a result, the speed of fabricating thin films by the spray-LBL method was markedly increased compared with that by the dipping LBL method.

  14. Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses

    PubMed Central

    Yan, Hanfei; Chu, Yong S.; Maser, Jörg; Nazaretski, Evgeny; Kim, Jungdae; Kang, Hyon Chol; Lombardo, Jeffrey J.; Chiu, Wilson K. S.

    2013-01-01

    For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts. PMID:23419650

  15. Nanoscale/multilayer gradient materials for application in electromagnetic gun systems

    SciTech Connect

    Otooni, M.A. [Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ (United States); Brown, I.G.; Anders, S.; Wang, Z. [Lawrence Berkeley Lab., CA (United States)

    1996-12-31

    Analysis of fired rails from electromagnetic railguns indicates severe surface damage occurs due to high current arcing and tribological mismatch. The authors have explored the behavior of several nanoscale multilayered materials as possible routes to improve the thermomechanical properties of the rail and armature materials. Structures investigated include (i) Ti-Co alloy on Ta-Cu alloy on dlc (diamond-like carbon) on stainless steel; (ii) Ti-Co alloy on Ta-Cu alloy on dlc on Cu, (iii) Ti-Co alloy on Ta-Cu on Cu; and (iv) Ti-Co on Ta-Cu alloy on Al. The alloys were all 50:50 at% and film thicknesses were fin the range 400--1,000 {angstrom}. The films were formed using a repetitively pulsed vacuum arc plasma deposition method with substrate biasing- and IBAD-like techniques. The surfaces were characterized by scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, optical microscopy, microhardness measurements, arc erosion resistance and scratch resistance tests. Preliminary results show improvement in the microhardness, arc erosion resistance and scratch resistance, most especially for the dlc-coated surfaces. This kind of multilayered approach to the fabrication of electromagnetic railgun and armature surfaces could be important for future advanced Electromagnetic EM Gun systems.

  16. Surface modification of 316L stainless steel with magnetron sputtered TiN/VN nanoscale multilayers for bio implant applications.

    PubMed

    Subramanian, B; Ananthakumar, R; Kobayashi, Akira; Jayachandran, M

    2012-02-01

    Nanoscale multilayered TiN/VN coatings were developed by reactive dc magnetron sputtering on 316L stainless steel substrates. The coatings showed a polycrystalline cubic structure with (111) preferential growth. XPS analysis indicated the presence of peaks corresponding to Ti2p, V2p, N1s, O1s, and C1s. Raman spectra exhibited the characteristic peaks in the acoustic range of 160-320 cm(-1) and in the optic range between 480 and 695 cm(-1). Columnar structure of the coatings was observed from TEM analysis. The number of adherent platelets on the surface of the TiN/VN multilayer, VN, TiN single layer coating exhibit fewer aggregation and pseudopodium than on substrates. The wear resistance of the multilayer coatings increases obviously as a result of their high hardness. Tafel plots in simulated bodily fluid showed lower corrosion rate for the TiN/VN nanoscale multilayer coatings compared to single layer and bare 316L SS substrate. PMID:22113251

  17. Nanoscale morphology of multilayer PbTe/CdTe heterostructures and its effect on photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Karczewski, G.; Szot, M.; Kret, S.; Kowalczyk, L.; Chusnutdinow, S.; Wojtowicz, T.; Schreyeck, S.; Brunner, K.; Schumacher, C.; Molenkamp, L. W.

    2015-03-01

    We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers with comparable thicknesses of 21 and 8 nm, respectively. However, the morphology of the resulting structures crucially depends on the growth temperature. The two-dimensional layered, superlattice-like character of the structures remains preserved only when grown at low substrate temperatures, such as 230 °C. The samples grown at the slightly elevated temperature of 270 °C undergo a morphological transformation to structures consisting of CdTe and PbTe pillars and columns oriented perpendicular to the substrate. Although the pillar-like objects are of various shapes and dimensions these structures exhibit exceptionally strong photoluminescence in the near infrared spectral region. At the higher growth temperature of 310 °C, PbTe and CdTe separate completely forming thick layers oriented longitudinally to the substrate plane. The observed topological transformations are driven by thermally activated atomic diffusion in the solid state phase. The solid state phase remains fully coherent during the processes. The observed topological transitions leading to the material separation in PbTe/CdTe system could be regarded as an analog of spinodal decomposition of an immiscible solid state solution and thus they can be qualitatively described by the Cahn–Hillard model as proposed by Groiss et al (2014 APL Mater. 2 012105).

  18. Nanoscale morphology of multilayer PbTe/CdTe heterostructures and its effect on photoluminescence properties.

    PubMed

    Karczewski, G; Szot, M; Kret, S; Kowalczyk, L; Chusnutdinow, S; Wojtowicz, T; Schreyeck, S; Brunner, K; Schumacher, C; Molenkamp, L W

    2015-03-27

    We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers with comparable thicknesses of 21 and 8 nm, respectively. However, the morphology of the resulting structures crucially depends on the growth temperature. The two-dimensional layered, superlattice-like character of the structures remains preserved only when grown at low substrate temperatures, such as 230 °C. The samples grown at the slightly elevated temperature of 270 °C undergo a morphological transformation to structures consisting of CdTe and PbTe pillars and columns oriented perpendicular to the substrate. Although the pillar-like objects are of various shapes and dimensions these structures exhibit exceptionally strong photoluminescence in the near infrared spectral region. At the higher growth temperature of 310 °C, PbTe and CdTe separate completely forming thick layers oriented longitudinally to the substrate plane. The observed topological transformations are driven by thermally activated atomic diffusion in the solid state phase. The solid state phase remains fully coherent during the processes. The observed topological transitions leading to the material separation in PbTe/CdTe system could be regarded as an analog of spinodal decomposition of an immiscible solid state solution and thus they can be qualitatively described by the Cahn-Hillard model as proposed by Groiss et al (2014 APL Mater. 2 012105). PMID:25751540

  19. Investigation of wear behavior and chip formation for cutting tools with nano-multilayered TiAlCrN\\/NbN PVD coating

    Microsoft Academic Search

    L. Ning; S. C. Veldhuis; K. Yamamoto

    2008-01-01

    A comprehensive investigation of the wear progress and chip formation was performed on an ultra-fine-grained cemented carbide ball nose end mill coated with a novel nano-multilayered TiAlCrN\\/NbN coating, by dry machining-hardened steel AISI H13 (HRC 55–57) at a cutting speed of 300m\\/min. Flank wear and cutting forces were measured as the wear progressed; chip temperatures were estimated. The surface morphology

  20. Laser beam induced nanoscale spot through nonlinear "thick" samples: A multi-layer thin lens self-focusing model

    NASA Astrophysics Data System (ADS)

    Wei, Jingsong; Yan, Hui

    2014-08-01

    Self-focusing is a well-researched phenomenon. Nanoscale spots can be achieved through self-focusing, which is an alternative method for achieving high-density data storage, high-resolution light imaging, and maskless nanolithography. Several research groups have observed that self-focusing spots can be reduced to nanoscale levels via incident laser power manipulation. Self-focusing spots can be analyzed by solving the nonlinear Schrödinger equation and the finite difference time domain method. However, both procedures are complex and time-consuming. In the present work, a multi-layer thin-lens self-focusing model that considers diffraction effects and changes of refractive index along the radial and film thickness directions is proposed to analyze the self-focusing behavior and traveling process of light beams intuitively. The self-focusing behaviors of As2S3 are simulated, and results show that a nanoscale self-focusing spot with a radius of about 0.12 ?m can be formed at the bottom of nonlinear sample when the incident laser power exceeds 4.25 mW. Our findings are basically consistent with experimental reports and provide a good method for analyzing and understanding the self-focusing process. An appropriate application schematic design is also provided.

  1. Magnetic Behaviour of Tb\\/Si Nanoscale Multilayers with Small Thickness of Rare Earth Layers

    Microsoft Academic Search

    A. V. Svalov; V. O. Vas'kovskiy; G. V. Kurlyandskaya; J. M. Barandiaran; N. N. Schegoleva; A. N. Sorokin

    2007-01-01

    We report the magnetic properties of Tb\\/Si multilayers obtained by rf-sputtering at the Tb layer thickness LTb = 3 nm. Analysis of the magnetization processes indicates more complex behaviour than canonical spin-glass transition. It is more probable that these multilayers contain both Tb superparamagnetic particles and Tb–Si spin-glass alloys.

  2. Enhancement of biocompatibility of metal implants by nanoscale tiN/NbN multilayer coatings.

    PubMed

    Subramanian, B

    2013-07-01

    Titanium nitride (TiN)/niobium nitride (NbN) nanostructured multilayer coatings were prepared by DC reactive magnetron sputtering method using the combination of a titanium and niobium target and an Ar-N2 mixture discharge gas on to 316L stainless steel substrates. The coatings showed a polycrystalline structure with (111) for TiN and (101) for NbN preferential growth. Raman spectroscopy measurements on the multilayer films exhibited the characteristic peaks at 212, 303, 458 and 578 cm-1. A higher hardness of 38 GPa was observed for TiN/NbN coatings. Electrochemical polarization tests were performed in simulated biological fluid solutions at 37 degreesC in order to determine and compare the corrosion behavior of the coated and uncoated 316L SS substrates. The TiN/NbN multilayer coatings could improve the corrosion resistance of 316L SS substrate. The bacterial culture experiments were performed and the bacteria treated samples were examined by epi fluorescence microscope measurements. PMID:23901475

  3. A transmission electron microscopy study of the deformation behavior underneath nanoindents in nano-scale Al-TiN multilayered composites

    SciTech Connect

    Bhattacharyya, Dhriti [Los Alamos National Laboratory; Mara, Nathan A [Los Alamos National Laboratory; Dickerson, Patricia O [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory; Hoagland, R G [Los Alamos National Laboratory

    2009-01-01

    Nano-scale multilayered Al-TiN composites were deposited with DC magnetron sputtering technique in two different layer thickness ratios - Al:TiN = 1:1 and Al:TiN = 9:1. The Al layer thickness varied from 2 nm to 450 nm. The hardness of the samples was tested by nanoindentation using a Berkovich tip. Cross-sectional Transmission Electron Microscopy (TEM) was carried out on samples extracted with Focused Ion Beam (FIB) from below the nanoindents. This paper presents the results of the hardness tests in the Al-TiN multilayers with the two different thickness ratios and the observations from the cross-sectional TEM studies of the regions underneath the indents. These studies showed remarkable strength in the multilayers, as well as some very interesting deformation behavior in the TiN layers at extremely small length scales, where the hard TiN layers undergo co-deformation with the Al layers.

  4. A new class of high performance PVD coatings for carbide cutting tools

    Microsoft Academic Search

    H. G Prengel; P. C Jindal; K. H Wendt; A. T Santhanam; P. L Hegde; R. M Penich

    2001-01-01

    A number of advanced PVD coating designs based on Ti–Al–N–C–B were evaluated in metalcutting. Monolayer PVD TiN, TiAlN, TiB2 and different variants of TiAlN multilayer coatings were deposited on WC-6 wt.% Co hardmetal inserts. The coatings were applied either by cathodic arc processes or a high-ionization magnetron sputtering process. The coated tools were evaluated in milling of ductile and gray

  5. Mechanics of nanoscale metallic multilayers: from atomic-scale to micro-scale

    SciTech Connect

    Wang, Jian [Los Alamos National Laboratory; Hoagland, Richard G [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory

    2008-01-01

    Layered composites of Cu/Nb with incoherent interfaces achieve very high strength levels. Interfaces play a crucial role in materials strength by acting as barriers to slip. Atomistic models of Cu/Nb bilayers are used to explore the origins of this resistance. The models clearly show that dislocations near an interface experience an attraction toward the interface. This attraction is caused by shear of the interface induced by the stress field of the dislocation. More importantly, atomistic simulations also reveal that interfacial dislocations easily move in interfaces by both glide and climb. Integrating these findings into a micro-scale model, we develop a three-dimensional crystal elastic-plastic model to describe the mechanical behavior of nanoscale metallic multi layers.

  6. Improvement of hot forging manufacturing with PVD and DUPLEX coatings

    Microsoft Academic Search

    Boris Navinšek; Peter Panjan; Frank Gorenjak

    2001-01-01

    The application of a DUPLEX treatment, which included low pressure pulsed plasma nitriding of AISI H11 tool steel dies and PVD BALINIT® FUTURA-TiN\\/TiAlN multilayered coating, was studied as a possible technology to improve the process of hot forging of steel components. The quality of the DUPLEX treatment was determined by laboratory analyses of coated test plates, which were treated together

  7. Nanoscale interfacial friction and adhesion on supported versus suspended monolayer and multilayer graphene.

    PubMed

    Deng, Zhao; Klimov, Nikolai N; Solares, Santiago D; Li, Teng; Xu, Hua; Cannara, Rachel J

    2013-01-01

    Using atomic force microscopy (AFM), supported by semicontinuum numerical simulations, we determine the effect of tip-subsurface van der Waals interactions on nanoscale friction and adhesion for suspended and silicon dioxide supported graphene of varying thickness. While pull-off force measurements reveal no layer number dependence for supported graphene, suspended graphene exhibits an increase in pull-off force with thickness. Further, at low applied loads, friction increases with increasing number of layers for suspended graphene, in contrast to reported trends for supported graphene. We attribute these results to a competition between local forces that determine the deformation of the surface layer, the profile of the membrane as a whole, and van der Waals forces between the AFM tip and subsurface layers. We find that friction on supported monolayer graphene can be fit using generalized continuum mechanics models, from which we extract the work of adhesion and interfacial shear strength. In addition, we show that tip-sample adhesive forces depend on interactions with subsurface material and increase in the presence of a supporting substrate or additional graphene layers. PMID:23215163

  8. EELS and ELNES studies of nano-scale nitride multilayers deposited by unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Seabourne, C. R.; Ross, I. M.; Rainforth, W. M.; Scott, A. J.; Mendis, B. G.; Hovespian, P. Eh

    2010-07-01

    High spatial resolution chemical analysis and imaging of a CrAlYN/CrN multi-layer coating was performed using sub-nanometer probe electron energy loss spectroscopy in a spherical aberration corrected scanning transmission electron microscope. Analysis indicated the CrN layers to be near stoichiometric with a relative Cr/N ratio of 1.05±0.1 while the CrAlYN layers gave a Cr/N ratio of 0.59±0.02. Analysis of the energy loss near edge structure at the nitrogen K-edge was performed. The experimentally determined fine edge structure in electron energy loss spectra were compared with theoretically determined spectra, calculated using electron density functional theory. For the CrN layers the best match between the direct experimental analysis and the simulated edges corresponds to stoichometric CrN consistent with the quantitative analysis while the best match for the CrAlYN layers was to (Cr0.5Al0.5)N.

  9. Cast iron cutting with nano TiN and multilayer TiN-CrN coated inserts

    NASA Astrophysics Data System (ADS)

    Perucca, M.; Durante, S.; Semmler, U.; Rüger, C.; Fuentes, G. G.; Almandoz, E.

    2012-09-01

    During the past decade great success has been achieved in the development of duplex and multilayer multi-functional surface systems. Among these surface systems outstanding properties have nanoscale multilayer coatings. Within the framework of the M3-2S project funded in the 7th European Framework Programme, several nanoscale multilayer coatings have been developed and investigated for experimental and industrial validation. This paper shows the performance of TiN and TiN/CrN nanoscale multilayer coatings on WC cutting inserts when machining GJL250 cast iron. The thin films have been deposited by cathodic arc evaporation in an industrial PVD system. The multilayer deposition characteristic and its properties are shown. The inserts have been investigated in systematic cutting experiments of cast iron bars on a turning machine specifically equipped for force measurements, accompanied by wear determination. Furthermore, equivalent experiments have been carried out on an industrial turning unit. Industrial validation criteria have been applied to assess the comparative performance of the coatings. The choice of the material and the machined parts is driven by an interest in automotive applications. The industrial tests show the need to further optimise the multi-scale modelling approach in order to reduce the lead time of the coating development as well as to improve simulation reliability.

  10. Optical multilayers with an amorphous fluoropolymer

    SciTech Connect

    Chow, R.; Loomis, G.E.; Lindsey, E.F.

    1994-07-01

    Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 run was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2}, SiO{sub 2}) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

  11. Structure and corrosion properties of PVD Cr-N coatings

    NASA Astrophysics Data System (ADS)

    Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

    2002-05-01

    PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

  12. Femtosecond Single-Shot Imaging of Nanoscale Ferromagnetic Order in Co/Pd Multilayers using Resonant X-ray Holography

    SciTech Connect

    Wang, Tianhan; Zhu, Diling; Benny Wu,; Graves, Catherine; Schaffert, Stefan; Rander, Torbjorn; Muller, leonard; Vodungbo, Boris; Baumier, Cedric; Bernstein, David P.; Brauer, Bjorn; Cros, Vincent; Jong, Sanne de; Delaunay, Renaud; Fognini, Andreas; Kukreja, Roopali; Lee, Sooheyong; Lopez-Flores, Victor; Mohanty, Jyoti; Pfau, Bastian; Popescu, 5 Horia

    2012-05-15

    We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm{sup 2}. Employing resonant spatially-muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm{sup 2}. Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics.

  13. Ignition properties of multilayer nanoscale reactive foils and the properties of metal-ceramic joints made with the same

    NASA Astrophysics Data System (ADS)

    Spey, Stephen John, Jr.

    A novel method for joining metals and ceramics using an Al-(Ni-7V) reactive multilayer foil as a heat source was studied. The components in the joint are first pre-wet or pre-metallized with a solder or braze before the reactive foil is placed between them and reacted, melting the solder or braze. On cooling, a solid joint is formed. It was shown using a SiC-Ti joint system that for a given joint system, there is are critical values for the foil's heat of reaction and total heat below which the braze in the joint will not melt, with foil heat of reaction having more of an impact than total heat. Experimental results from Al-Al and Al2O3-Al2O3 joint systems showed that the interface between the solder and the joint component can play a critical role in determining joint strength. Experimental results and numerical predictions using Al-Al2O3 and Al-glass joint systems showed that the elastic strain energy (ESE) and residual stress in a metal-ceramic reactive foil have two sources: The bending, caused by the uneven thermal profile across each joint component created by the reacting foil, that the joint components undergo while the solder or braze is molten and which is locked in when the solder or braze solidifies, and uneven average thermal contraction between the two components. The distribution of elastic strain energy and stress in a reactive foil joint is determined by the thermal diffusivities and coefficients of thermal expansion of the two joint components. The ignition requirements of reactive foils were investigated using two experimental methods, an electric pulse and mechanical stab detonation, and a numerical simulation of the electric pulse ignition method. Experimental results and numerical predictions showed that increasing foil bilayer or increasing intermixed layer thickness will make a foil more difficult to ignite. An estimated energy density of 1GJ/m3 was found experimentally to be an upper limit of the minimum energy density required for ignition of a 1:1 molar ratio Al-(Ni-7V) reactive foil with 50nm bilayers and a 2.25nm intermixed layer thickness. An autoignition temperature of approximately 419K was found using both experimental results and numerical predictions, both of which accounted for heat spreading during an ignition attempt.

  14. Optical multilayer films based on an amorphous fluoropolymer

    SciTech Connect

    Chow, R.; Loomis, G.E.; Ward, R.L. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    1996-01-01

    Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, and with other optical materials. A high reflector for 1064 nm light was made with ZnS and AF2400. An all-organic 1064 nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2} and SiO{sub 2}) compatibility with AF2400 was also tested. The multilayer morphologies were influenced by coating stress and unintentional temperature rises from the PVD process. Analysis by liquid nuclear magnetic resonance of the thin films showed slight compositional variations between the coating and starting materials of perfluorinated amorphous polymers.

  15. Effect of Modulation Period and N + Beam Bombarding Energy on the growth of Nanoscale ZrB2/AlN Multilayered Coatings Prepared by IBAD

    NASA Astrophysics Data System (ADS)

    Sun, Y. D.; Tan, M.; Gong, J.; Liu, M. Y.; Liu, G. Q.; Deng, X. Y.; Li, D. J.

    Monolithic ZrB2, AlN, and ZrB2/AlN multilayered coatings have been synthesized by ion beam assisted deposition at room temperature. Scanning electron microscopy, X-ray diffraction, XP-2 profiler and nano indenter were employed to investigate the influences of modulation period and N + bombarding energy on microstructure and mechanical properties of the coatings. Most of multilayered coatings revealed higher hardness and elastic modulus than the rule-of-mixtures value of monolithic ZrB2 and AlN coatings. N + bombardment at 300 eV resulted in ZrB2/AlN multilayered coating the highest hardness (31.2 GPa) and elastic modulus (372.2 GPa). This hardest multilayer also showed the improved residual stress and fracture resistance. These improved performances are likely a result of more efficient momentum transfer to the deposition particles due to the proper N + bombarding energy.

  16. The effects of rapid thermal annealing on the electrical, optical, and structural properties of Nb:TiO2 multilayer electrodes with an inserted nanoscale Ag layer for organic solar cells

    NASA Astrophysics Data System (ADS)

    Park, Jun-Hyuk; Choi, Yoon-Young; Kim, Han-Ki; Lee, Hyun Hwi; Na, Seok-In

    2010-10-01

    We investigated the effects of rapid thermal annealing (RTA) on the electrical, optical, structural, interfacial, and surface properties of Nb:TiO2 (NTO)-Ag-NTO multilayer electrodes inserting a nanoscale Ag layer for application in organic solar cells (OSCs). Up to an annealing temperature of 500 °C, the resistivity and optical transmittance of the NTO-Ag-NTO electrodes were stably maintained due to the absence of Ag outdiffusion. The effective activation of the Nb in the NTO layer led to a slight decrease in the resistivity and an increase in the band gap caused by the Burstein-Moss effect. However, increasing the RTA temperature above 600 °C resulted in degradation of the NTO-Ag-NTO multilayer electrode due to severe Ag diffusion. Based on the synchrotron x-ray scattering and x-ray photoelectron spectroscopy analyses results, the electrical properties of the NTO-Ag-NTO electrodes are correlated with the microstructure and interfacial diffusion of each layer. In addition, it was found that the performance of the OSC was critically dependent on the RTA temperature of the NTO-Ag-NTO electrodes even though the as-deposited NTO-Ag-NTO electrode had a fairly low resistivity. This indicates that the activation of Nb dopants in the top NTO layer plays an important role in the extraction of carriers from the organic layer to the anode (NTO-Ag-NTO) electrode.

  17. Protection of yttria-stabilized zirconia for dental applications by oxidic PVD coating.

    PubMed

    Hübsch, C; Dellinger, P; Maier, H J; Stemme, F; Bruns, M; Stiesch, M; Borchers, L

    2015-01-01

    In this study, the application of transparent physical vapor deposition (PVD) coatings on zirconia ceramics was examined as an approach to retard the low-temperature degradation of zirconia for dental applications. Transparent monolayers of titanium oxide (TixOy) and multilayers consisting of titanium oxide-alumina-titanium oxide (TixOy-AlxOy-TixOy) were deposited onto standardized discs of 3Y-TZP using magnetron sputtering. Using X-ray photospectroscopy and time-of-flight secondary-ion mass spectrometry, the compositions of the coatings were verified, and an approximate thickness of 50 nm for each type of coating was ascertained. After aging the coated and uncoated samples in water vapor at 134°C and 3 bar for 4, 8, 16, 32, 64 and 128 h, the monoclinic phase content was determined using X-ray diffraction, and its impact on mechanical properties was assessed in biaxial flexural strength tests. In addition, the depth of the transformation zone was measured from scanning electron microscopy images of the fracture surfaces of hydrothermally aged samples. The results revealed that the tetragonal-to-monoclinic phase transformation of the zirconia ceramic was retarded by the application of PVD coatings. During the first stages of aging, the coated samples exhibited a significantly lower monoclinic phase content than the uncoated samples and, after 128 h of aging, showed a transformation zone which was only ?12-15 ?m thick compared to ?30 ?m in the control group. Biaxial flexural strength decreased by ?10% during aging and was not influenced by the application of a PVD coating. PMID:25278443

  18. On the structure and oxidation mechanisms in nanoscale hard coatings

    NASA Astrophysics Data System (ADS)

    Rainforth, W. Mark; Zhou, Z.

    2006-02-01

    Thin-film structures consisting of alternating nanoscale multilayers show substantial hardness increases compared with monolithic coatings of the constituent materials. Coatings, such as TiAlN/VN are deposited using PVD with individual coating bi-layer thickness of ~3nm. Since TiAlN and VN are isostructural and mutually soluble, mixing of the two layers during deposition is expected, which will inevitably affect properties. Energy filtered TEM using a field emission gun source allowed important information on layer structure, but failed to reveal details <1nm. Spherical aberration corrected scanning transmission electron microscopy (STEM) allowed the composition of individual atomic columns to be probed, which yielded a good match between experiment and numerical models of the layer mixing. For high speed machining operations, the oxidation behaviour of coatings becomes an important consideration. Static oxidation of TiAlN/VN films was studied in the range 550-700oC, and characterised by high temperature in-situ XRD and STEM/EDX/EELS of selected surface cross-sections. Oxidation of the TiAlN/VN coating started at >=550°C with the VN being the first component to oxidise. At temperatures >600°C, a duplex oxide structure was formed, with several phases observed, including V2O5, TiO2 and AlVO4, with V2O5 being the dominant oxide at the outer layer at 638°C. These coatings exhibit low friction in dry sliding which is believed to arise from the inherently low friction of V2O5. Focused ion beam studies of wear tests at 630°C confirmed that the contact surface comprised small (~50nm), equiaxed and largely agglomerated V2O5 crystals, confirming the hypothesis.

  19. Vapor Phase Deposition Using Plasma Spray-PVD

    NASA Astrophysics Data System (ADS)

    von Niessen, K.; Gindrat, M.; Refke, A.

    2010-01-01

    Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

  20. Physical Vapor Deposition Barriers for Cu metallization - PVD Barriers

    NASA Astrophysics Data System (ADS)

    Koike, Junichi

    Cu is an interstitial impurity in Si and its diffusivity in Si is faster than other transition metals and of the order of 10-5 to 10-7 cm2/s in the temperature range of 200-500°C [1]. Electronically, Cu is a deep-level dopant in Si and forms various donor and acceptor levels, inducing current leakage [2, 3]. In a multilayered device structure, Cu diffuses through a dielectric layer and reaches a Si substrate under electric bias field [4]. In order to prevent Cu diffusion, a barrier layer is necessary at an interface between Cu and the dielectric layers. By the use of high-resistivity barrier metal, the effective resistivity of interconnect lines increases with the advancement of the technology node as shown in Fig. 21.1 [5, 6]. For a fixed barrier thickness of 10 nm, for example, effective resistivity increases rapidly from 2.35 ?? cm for the 65 nm node to 2.85 ?? cm for the 32 nm node. Meanwhile, the effective resistivity of 2.2 ?? cm should be maintained in order to minimize RC delay [7]. This recommendation by the International Technology Roadmap for Semiconductors (ITRS) determines a required barrier thickness at a given technology node. In the 32 nm node, the barrier thickness should be 3.5 nm, approximately 10 atomic layers to prevent interdiffusion between Cu and the dielectric layer. In order to achieve this requirement, a proper barrier material should be deposited using proper deposition techniques and conditions. Wang et al. summarized the published data as of the year 1993 together with their investigation of TiW barrier [8]. Kaloyeros and Eisenbraun [9] published an excellent review of barrier materials as of 2000. In their review article, advantages and limitations of various barrier materials were described in detail based on numerous experimental works by others. Readers can find in this article how and why Ta/TaN barrier had come to use for the Cu interconnect. Since then, technology has rapidly advanced along the line of the ITRS roadmap. Once the technology node entered to a sub-micrometer range, barrier thickness becomes a critical issue to ensure expected performance and reliability of advanced devices. Barrier materials and processes need to be revisited from fundamental viewpoint. In this chapter, the issues of physical vapor deposited (PVD) barrier will be discussed in terms of metallurgical and thermodynamic aspects.

  1. Conceptualizing Nanoscale

    NSDL National Science Digital Library

    Thomas Tretter

    2006-12-01

    One strategy for enhancing students' understanding of nanoscale is to shift students' existing understandings of relative scale by helping them conceptually transport their strongest scale benchmark--themselves--into the nanoscale world. This article describes a set of activities to scaffold high school students' nanoscsale conceptions and to help them appreciate the scale at which nanotechnology operates, both in a relative and an absolute sense.

  2. Contact fatigue behavior of PVD-coated hardmetals

    Microsoft Academic Search

    E. Tarrés; G. Ramírez; Y. Gaillard; E. Jiménez-Piqué; L. Llanes

    2009-01-01

    There is an increasing usage of PVD-coated hardmetals in applications where contact loads of cyclic nature between curved surfaces are common, e.g. cold forming tools and machine components. Thus, knowledge of both the mechanical response and the damage mechanisms involved during contact fatigue of these systems is required if they want to be used effectively. In this investigation this is

  3. Antimicrobial titanium\\/silver PVD coatings on titanium

    Microsoft Academic Search

    Andrea Ewald; Susanne K Glückermann; Roger Thull; Uwe Gbureck

    2006-01-01

    BACKGROUND: Biofilm formation and deep infection of endoprostheses is a recurrent complication in implant surgery. Post-operative infections may be overcome by adjusting antimicrobial properties of the implant surface prior to implantation. In this work we described the development of an antimicrobial titanium\\/silver hard coating via the physical vapor deposition (PVD) process. METHODS: Coatings with a thickness of approximately 2 ?m

  4. Multifunctional multi-component PVD coatings for cutting tools

    Microsoft Academic Search

    M. Kathrein; C. Michotte; M. Penoy; P. Polcik; C. Mitterer

    2005-01-01

    Highly wear resistant PVD coatings are well established in cutting operations. Further efforts to improve the cutting performance need to be focused on all relevant wear mechanisms. Thus, the objectives are an enhancement of the abrasive wear resistance, toughness, oxidation resistance, and reduction of friction. The aim of this work was to investigate properties and cutting performance of new multifunctional

  5. Nanoscale Multilayer CIS Thin Film Characterization

    Microsoft Academic Search

    R. P. Raffaelle; J. G. Mantovani; H. Forsell; D. Palacios; P. Kalmanson; O. Melendez; J. Hurley

    1997-01-01

    We have been investigating the electrochemical deposition of CdS and CuInSe2 (CIS) for use in thin film solar cells. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells due to its favorable optical absorption and electrical characteristics. We have incorporated this material into nanometer scale layers in which the Cu to In ratio is periodically

  6. Some Materials Science Aspects of PVD Hard Coatings

    Microsoft Academic Search

    Christian Mitterer; Paul H. Mayrhofer

    2001-01-01

    Hard coatings deposited by Physical Vapor Deposition (PVD) based on the transition element nitrides are nowadays widely applied\\u000a to reduce wear and corrosion of tools. In the last two decades, tremendous advances have been achieved in the development\\u000a of deposition and application technology of hard coatings. The methods to be applied to optimize coating properties are known\\u000a from materials science,

  7. PVD improvement combined with surcharge and vacuum preloading including simulations

    Microsoft Academic Search

    J. Saowapakpiboon; D. T. Bergado; P. Voottipruex; L. G. Lam; K. Nakakuma

    2011-01-01

    This paper presents the study of PVD improved reconstituted specimen with and without vacuum preloading on large-scale consolidometer in the laboratory tests. Subsequently, the results of the laboratory tests were analyzed and simulated by 2D (axisymmetric) finite element method (FEM) to back-analyze and confirm the related design parameters which were used further in subsequent numerical experiments. The laboratory test results

  8. Preparation and characterization of PVdF nanofiber ion exchange membrane for the PEMFC application

    Microsoft Academic Search

    Won Gi Jang; Jian Hou; Hong sik Byun

    2011-01-01

    This paper reports the preparation and characterization of polyvinylidene fluoride (PVdF) nanofiber ion exchange membrane for the application in polymer electrolyte membrane fuel cells (PEMFC). The composite membrane of PS\\/PVdF was prepared by using the electrospinning method with PVdF solution in a mixed solvent of DMAc and acetone by pore-filling with a mixture of styrene and PS using DVB as

  9. Evolution of self-organization in nano-structured PVD coatings under extreme tribological conditions

    NASA Astrophysics Data System (ADS)

    Fox-Rabinovich, G.; Kovalev, A.; Aguirre, M. H.; Yamamoto, K.; Veldhuis, S.; Gershman, I.; Rashkovskiy, A.; Endrino, J. L.; Beake, B.; Dosbaeva, G.; Wainstein, D.; Yuan, Junifeng; Bunting, J. W.

    2014-04-01

    The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after length of cut of 15 m) fully protective mullite tribo-films predominantly form on the surface of nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. This reduces entropy production during friction and leads to significant surface damage reduction and wear rate stabilization. In contrast, in a monolayer coating with a lower structural complexity, a variety of protective and non-protective tribo-films form during the running-in stage, which cannot fully protect the surface. Therefore the wear rate on the monolayer is not stabilized and its wear resistance is lower. The results obtained show that it is possible to control tribo-films evolution during self-organization by means of increase in structural complexity and the non-equilibrium state of the surface engineered layer with simultaneous tuning of its integrative behaviour.

  10. Nanoscale Proteomics

    SciTech Connect

    Shen, Yufeng; Tolic, Nikola; Masselon, Christophe D.; Pasa-Tolic, Liljiana; Camp, David G.; Anderson, Gordon A.; Smith, Richard D.; Lipton, Mary S.

    2004-02-01

    This paper describes efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies, i.e. nanoscale proteomics. The approach combines high-efficiency nano-scale LC with advanced MS, including high sensitivity and high resolution Fourier transform ion cyclotron resonance (FTICR) MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology developed enables large-scale protein identification from nanogram size proteomic samples and characterization of more abundant proteins from sub-picogram size complex samples. Protein identification in such studies using MS is feasible from <75 zeptomole of a protein, and the average proteome measurement throughput is >200 proteins/h and ~3 h/sample. Higher throughput (>1000 proteins/h) and more sensitive detection limits can be obtained using a “accurate mass and time” tag approach developed at our laboratory. These capabilities lay the foundation for studies from single or limited numbers of cells.

  11. Interfacial damage in EB-PVD thermal barrier coatings due to thermal cycling

    Microsoft Academic Search

    Z. A Chaudhury; G. M Newaz; S. Q Nusier; T Ahmed

    1997-01-01

    Optical microscopy, acoustic microscopy, and thermal wave imaging techniques were used to characterize the interfacial damage in a thermal barrier coated single crystal superalloy subjected to thermal cycling. The thermal barrier coating (TBC) was applied to the superalloy using electron beam physical vapor deposition (EB-PVD) technique. The EB-PVD system seems to be stable at least up to the temperature of

  12. ENHANCEMENT OF PVD PERFORMANCE ON SOFT BANGKOK CLAY BY THERMAL, ELECTRO-OSMOTIC AND VACUUM TECHNIQUES

    Microsoft Academic Search

    T. Tanchaisawat; D. T. Bergado; J. Saowapakpiboon

    This paper examines the innovative techniques for enhancing the performance of the prefabricated vertical drain (PVD) consisting of thermal, electro-osmotic and vacuum consolidation techniques. The electro-osmotic consolidation of soft Bangkok clay using copper and carbon electrodes with PVD was first studied. Laboratory testing program were done on undisturbed and reconstituted sample in large consolidometer under voltage gradient of 60 and

  13. Nanoscale 2013

    NASA Astrophysics Data System (ADS)

    Koenders, Ludger; Ducourtieux, Sebastien

    2014-04-01

    The accurate determination of the properties of micro- and nano-structures is essential in research and development. It is also a prerequisite in process control and quality assurance in industry. In most cases, especially at the nanometer range, knowledge of the dimensional properties of structures is the fundamental base, to which further physical properties are linked. Quantitative measurements presuppose reliable and stable instruments, suitable measurement procedures as well as calibration artifacts and methods. This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2013 seminar held in Paris, France, on 25 and 26 April. It was the 6th Seminar on NanoScale Calibration Standards and Methods and the 10th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Nanometrology Group of the Technical Committee-Length of EURAMET, the Physikalisch-Technische Bundesanstalt and the Laboratoire National de Métrologie et d'Essais. Three satellite meetings related to nanometrology were coupled to the seminar. The first one was an open Symposium on Scanning Probe Microscopy Standardization organized by the ISO/TC 201/SC9 technical committee. The two others were specific meetings focused on two European Metrology Research Projects funded by the European Association of National Metrology Institutes (EURAMET) (see www.euramet.org), the first one focused on the improvement of the traceability for high accuracy devices dealing with sub-nm length measurement and implementing optical interferometers or capacitive sensors (JRP SIB08 subnano), the second one aiming to develop a new metrological traceability for the measurement of the mechanical properties of nano-objects (JRP NEW05 MechProNo). More than 100 experts from industry, calibration laboratories and metrology institutes from around the world joined the NanoScale 2013 Seminar to attend 23 oral and 64 poster presentations. From these contributions, 22 are included as articles in this special issue of Measurement Science and Technology . They cover some novel scientific results that are representative of the topics currently being investigated in the field of European and world-wide nanometrology. Half of the articles presented in this special issue are linked to a quantitative use of atomic force microscopes (AFM) and related techniques. This is not surprising since atomic force microscopy with scanning electron microscopy (SEM) and scatterometry are the most used techniques to practice metrology at the nanometer scale. The presented developments around AFM mainly concern solutions to improve its performance, such as for example by increasing the scanning speed using dynamic control, its measurement range by using long-range AFM and even by automatically replacing the tip with 10 nm repositioning. The search for a better traceability is still on-going and a comparison of SEM and AFM organized in the Northern Europe research institutes illustrates this question well. But nowadays measurement on advanced product structures requires 3D capabilities. This can be achieved by using a new type of tilting AFM or more dedicated critical dimension (CD) AFMs that will use specific tips whose cantilever is sensitive in three dimensions. A perfect illustration of this are the results presented for the measurement of CD and sidewall on EUV photomasks. Calibration of the cantilever spring constant is still carried on and two papers present the latest developments. Finally, as past Nanoscale issues have witnessed, scanning probe microscopes are more and more used for metrological applications where the quantities to be measured are no longer dimensional, for example, thermal conductivity on delaminated thin films using a scanning thermal microscope, the carrier concentration on CIGS solar cells using a scanning capacitance microscope (SCM) or the surface potential measured by a Kelvin probe microscope. But in all cases, what these special developments share is a metrological approach, and for

  14. Application of PVD methods to solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Solovyev, A. A.; Sochugov, N. S.; Rabotkin, S. V.; Shipilova, A. V.; Ionov, I. V.; Kovalchuk, A. N.; Borduleva, A. O.

    2014-08-01

    In this paper, attention is paid to the application of such a method of vacuum physical vapor deposition (PVD) as magnetron sputtering for fabrication of a solid oxide fuel cell (SOFC) materials and structures. It is shown that the YSZ (yttria-stabilized zirconia) electrolyte and Ni-YSZ anode layers with required thickness, structure and composition can be effectively formed by PVD methods. The influence of parameters of pulsed power magnetron discharge on the deposition rate and the microstructure of the obtained YSZ electrolyte films were investigated. It is shown that the deposition rate of the oxide layers by magnetron sputtering can be significantly increased by using asymmetric bipolar power magnetrons, which creates serious prerequisites for applying this method on the industrial scale. Porous Ni-YSZ anode films were obtained by reactive co-sputtering of Ni and Zr-Y targets and subsequent reduction in the H2 atmosphere at a temperature of 800 °C. The Ni-YSZ films comprised small grains and pores of tens of nanometers.

  15. EDITORIAL: Nanoscale metrology Nanoscale metrology

    NASA Astrophysics Data System (ADS)

    Klapetek, P.; Koenders, L.

    2011-09-01

    This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2010 seminar held in Brno, Czech Republic. It was the 5th Seminar on Nanoscale Calibration Standards and Methods and the 9th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Czech Metrology Institute (CMI) and the Nanometrology Group of the Technical Committee-Length of EURAMET. There were two workshops that were integrated into NanoScale 2010: first a workshop presenting the results obtained in NANOTRACE, a European Metrology Research Project (EMRP) on displacement-measuring optical interferometers, and second a workshop about the European metrology landscape in nanometrology related to thin films, scanning probe microscopy and critical dimension. The aim of this workshop was to bring together developers, applicants and metrologists working in this field of nanometrology and to discuss future needs. For more information see www.co-nanomet.eu. The articles in this special issue of Measurement Science and Technology cover some novel scientific results. This issue can serve also as a representative selection of topics that are currently being investigated in the field of European and world-wide nanometrology. Besides traditional topics of dimensional metrology, like development of novel interferometers or laser stabilization techniques, some novel interesting trends in the field of nanometrology are observed. As metrology generally reflects the needs of scientific and industrial research, many research topics addressed refer to current trends in nanotechnology, too, focusing on traceability and improved measurement accuracy in this field. While historically the most studied standards in nanometrology were related to simple geometric structures like step heights or 1D or 2D gratings, now we are facing tasks to measure 3D structures and many unforeseen questions arising from interesting physical properties of nanoparticles, nanotubes, quantum dots and similar fascinating objects. Currently there is a high level of interest in characterization of nanoparticles since they are increasingly encountered in science, technology, life sciences and even everyday life. Quantitative characterization of nanoparticles has been the subject of many discussions and some recent work over the last couple of years, and both scanning probe microscopy and scanning or transmission electron microscopy characterization of nanoparticles are presented here. There is also a continuous need for improvement of scanning probe microscopy that is a basic tool for nanometrology. Increasing thermal stability, scanning speed and tip stability, improving traceability and reducing uncertainty are all areas being addressed. As scanning probe microscopy is essentially based on force measurements in the nano- and piconewton range, we take notice of large developments, both theoretical and experimental, in the field of traceable measurements of nanoscale forces. This will greatly increase the understanding and quantification of many basic phenomena in scanning probe microscopy. Finally, we observe that high resolution techniques for acquiring more than just morphology are slowly shifting from purely qualitative tools to well defined quantitative methods. Lack of simple and reliable chemical identification in scanning probe microscopy is compensated by many other local probing methods seen in commercial microscopes, like scanning thermal microscopy or the Kelvin probe technique. All these methods still require underpinning with theoretical and experimental work before they can become traceable analytical methods; however, the increased interest in the metrology community gives rise to optimism in this field. The production of this issue involved considerable effort from many contributors. We would like to thank all the authors for their contributions, the referees for their time spent reviewing the contributions and their valuable comments, and the whole Editorial Board of Measurement Science and Tec

  16. Macroscale vs. Nanoscale

    NSDL National Science Digital Library

    In this colorful, interactive object, learners examine how materials on the nanoscale compare with those on the macroscale. The focus is on the difference between macroscale and nanoscale gold in both color and melting point.

  17. Adhesion of PVD layers on liquid crystal polymer pretreated by oxygen-containing plasma

    Microsoft Academic Search

    B. Wang; W. Eberhardt; H. Kück

    2005-01-01

    The low-pressure plasma pretreatment of liquid crystal polymer (LCP) before PVD metallization is presented. More polar functional groups were present on the substrate surface after oxygen-containing plasma pretreatment. The adhesion strength between PVD Cu\\/Cr layers and LCP substrates is enhanced with high concentration of oxygen in a gas mixture of oxygen and argon used for plasma pretreatment. Thermal shock test

  18. The role of PVD TiN coating in wear behaviour of aluminium extrusion die

    Microsoft Academic Search

    M. B. Karami?; H. Sert

    1998-01-01

    In this study, the wear behaviour and surface properties of a PVD TiN coated extrusion die were investigated. Both an extrusion die for aluminium profiles and the samples manufacturing from AISI H13 steel were hardened, tempered, nitrided and TiN coated by PVD method. The microhardnesses on the coated surface and cross-section of both nitrided and coated samples were determined. The

  19. Influence of Pseudomonas aeruginosa pvdQ Gene on Altering Antibiotic Susceptibility Under Swarming Conditions

    Microsoft Academic Search

    Lili Wang; Chunling Zhang; Fengyun Gong; Hongtao Li; Xuhua Xie; Chao Xia; Jia Chen; Ying Song; Aixia Shen; Jianxin Song

    2011-01-01

    In Pseudomonas aeruginosa PAO1, the pvdQ gene has been shown to have at least two functions. It encodes the acylase enzyme and hydrolyzes 3-oxo-C12-HSL, the key signaling\\u000a molecule of quorum sensing system. In addition, pvdQ is involved in swarming motility. It is required for up-regulated during swarming motility, which is triggered by high cell\\u000a densities. As high-density bacterial populations also

  20. Antibacterial PVD coatings doped with silver by ion implantation

    NASA Astrophysics Data System (ADS)

    Osés, J.; Palacio, J. F.; Kulkarni, S.; Medrano, A.; García, J. A.; Rodríguez, R.

    2014-08-01

    The antibacterial effect of certain metal ions, like silver, has been exploited since antiquity. Obviously, the ways to employ the biocide activity of this element have evolved throughout time and it is currently used in a wide range of clinical applications. The work presented here reports the results of an investigation focused on combining the protective properties of PVD coatings with the biocide property of silver, applied by ion implantation. For this purpose, chromium nitride layers were doped with silver implanted at two different doses (5 × 1016 and 1 × 1017 ion/cm2) at 100 keV of energy and perpendicular incidence. Full characterization of the coatings was performed to determine its topographical and mechanical properties. The concentration profile of Ag was analyzed by GD-OES. The thickness of the layers, nano-hardness, roughness, wear resistance and coefficient of friction were measured. Finally, the anti-bacterial efficacy of the coatings was determined following the JIS Z-2801:2010 Standard. The results provide clear insights into the efficacy of silver for antibacterial purposes, as well as on its influence in the mechanical and tribological behaviour of the coatings matrix.

  1. Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

    NASA Astrophysics Data System (ADS)

    von Niessen, Konstantin; Gindrat, Malko

    2011-06-01

    Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion resistance but also the simultaneous coverage of multiple air foils.

  2. Nanoscale thermal probing

    PubMed Central

    Yue, Yanan; Wang, Xinwei

    2012-01-01

    Nanoscale novel devices have raised the demand for nanoscale thermal characterization that is critical for evaluating the device performance and durability. Achieving nanoscale spatial resolution and high accuracy in temperature measurement is very challenging due to the limitation of measurement pathways. In this review, we discuss four methodologies currently developed in nanoscale surface imaging and temperature measurement. To overcome the restriction of the conventional methods, the scanning thermal microscopy technique is widely used. From the perspective of measuring target, the optical feature size method can be applied by using either Raman or fluorescence thermometry. The near-field optical method that measures nanoscale temperature by focusing the optical field to a nano-sized region provides a non-contact and non-destructive way for nanoscale thermal probing. Although the resistance thermometry based on nano-sized thermal sensors is possible for nanoscale thermal probing, significant effort is still needed to reduce the size of the current sensors by using advanced fabrication techniques. At the same time, the development of nanoscale imaging techniques, such as fluorescence imaging, provides a great potential solution to resolve the nanoscale thermal probing problem. PMID:22419968

  3. Pyoverdine-Mediated Iron Uptake in Pseudomonas aeruginosa: the Tat System Is Required for PvdN but Not for FpvA Transport

    Microsoft Academic Search

    R. Voulhoux; A. Filloux; I. J. Schalk

    2006-01-01

    Under iron-limiting conditions, Pseudomonas aeruginosa PAO1 secretes a fluorescent siderophore called pyoverdine (Pvd). After chelating iron, this ferric siderophore is transported back into the cells via the outer membrane receptor FpvA. The Pvd-dependent iron uptake pathway requires several essential genes involved in both the synthesis of Pvd and the uptake of ferric Pvd inside the cell. A previous study describing

  4. Innovative Al Damascene Process for Nanoscale Interconnects

    Microsoft Academic Search

    Kyung-In Choi; Sung-Ho Han; Sera Yun; Dae-Yong Kim; Jong Won Hong; Sang Woo Lee; Byung Hee Kim; Sung-Tae Kim; U-In Chung; Joo-Tae Moon; Byung-Il Ryu

    2006-01-01

    A novel chemical vapor deposition (CVD)-Al technique of ``bottom-up growth'' was developed using methylpyrrolidine alane as a precursor and a (PVD)-TiN\\/CVD-TiN stacked barrier in a damascene structure. Poor step coverage of PVD-TiN caused an absence of PVD-TiN at the bottom of trenches, resulting in selective Al growth. The new method filled a 40-nm-wide trench (aspect ratio = 7.5) completely and

  5. Characterization of Mo/Si multilayer growth on stepped topographies

    SciTech Connect

    Boogaard, A. J. R. vcan den; Louis, E.; Zoethout, E.; Goldberg, K. A.; Bijkerk, F.

    2011-08-31

    Mo/Si multilayer mirrors with nanoscale bilayer thicknesses have been deposited on stepped substrate topographies, using various deposition angles. The multilayer morphology at the stepedge region was studied by cross section transmission electron microscopy. A transition from a continuous- to columnar layer morphology is observed near the step-edge, as a function of the local angle of incidence of the deposition flux. Taking into account the corresponding kinetics and anisotropy in layer growth, a continuum model has been developed to give a detailed description of the height profiles of the individual continuous layers. Complementary optical characterization of the multilayer system using a microscope operating in the extreme ultraviolet wavelength range, revealed that the influence of the step-edge on the planar multilayer structure is restricted to a region within 300 nm from the step-edge.

  6. Polyelectrolyte Multilayers

    NASA Astrophysics Data System (ADS)

    Schaaf, P.; Voegel, J.-C.

    The films known as polyelectrolyte multilayers are made by alternating deposition of polyanions (negatively charged polymers) and polycations (positively charged polymers). The development of these films, invented in the 1990s [1,3], has seen a considerable burst of interest, in particular due to their many applications. Indeed, these films are used to make electroluminescent diodes [4], anti-reflecting surfaces [5], water filtering substrates [6], and substrates for the separation of chiral molecules [7]. The alternating deposition of positive and 12 negative species can also be used to make films with a mechanical strength close to that of steel [8]. Applications to biosensors and especially biomaterials are currently under investigation [9]. This is the last example discussed in the present chapter. Polyelectrolytes are charged polymers, usually soluble in an aqueous solution. When a surface, supposed negatively charged, is set in contact with a solution of polycations (positively charged polyelectrolytes), the chains will immediately interact with the surface via electrostatic interaction and adsorb onto it. Like any other polymer, polyelectrolytes do not adsorb lengthwise against the surface, but form loops and tails. This adsorption is generally irreversible, and replacing the polycation solution by the solvent (water) alone will only lead to very slight desorption. This irreversibility of adsorption results from the formation of many anchoring points with the surfaces along the long polymer chains. Even if the interaction energy between a monomer, the basic building block of the polymer, and a surface is small, the fact that a number of contact points are set up makes the overall interaction between a polymer and a surface rather strong. Furthermore, in order for a chain to desorb, all the anchor points on the surface must be broken simultaneously, and such an event is highly improbable.

  7. Nanoscale construction with DNA

    NASA Astrophysics Data System (ADS)

    Douglas, Shawn

    2013-03-01

    The programmability of DNA makes it an attractive material for constructing intricate nanoscale shapes. One method for creating these structures is DNA origami, in which a multiple-kilobase single-stranded ``scaffold'' is folded into a custom nanoscale shape by interacting with hundreds of short oligonucleotide ``staple'' strands. I will talk about our efforts to realize demand-meeting applications of this method, including our recent development of nanoscale devices to mimic cell-signaling stimulation carried out by our own immune systems.

  8. Cutting performance increasing in gear hobbing by means of HSS hobs, coated with effective PVD films

    Microsoft Academic Search

    K.-D. Bouzakis; S. Kombogiannis; O. Friderikos; J. Anastopoulos

    Coated tools experience a rapid development due to the increased demands towards cutting performance improvement and production cost diminishing. In order to meet corresponding requirements in gear manufacturing, impressive developments, among others, in the area of coating technology, have been realized. In order to investigate the effectiveness of various innovative PVD films, fly hobbing wear experiments in individual generating positions

  9. EVOLUTION OF POROSITY AND TEXTURE IN THERMAL BARRIER COATINGS GROWN BY EB-PVD

    E-print Network

    Clarke, David R.

    .e. high resistance to spalling under thermal cycling [3]. The latter is not a property of the thermalEVOLUTION OF POROSITY AND TEXTURE IN THERMAL BARRIER COATINGS GROWN BY EB-PVD Scott G. Terry, 93106-5050 Abs tract The pattern and distribution of porosity in the columnar microstructure of thermal

  10. Characterization of PVD Aluminum Nitride for Heat Spreading in RF IC's

    E-print Network

    Technische Universiteit Delft

    Characterization of PVD Aluminum Nitride for Heat Spreading in RF IC's L. La Spina, L. K. Nanver Abstract--Physical-vapor-deposited aluminum nitride, developed for heat spreading in RF ICs-stress aluminum nitride (AlN) layer was developed and it was shown that the basic material properties were

  11. Advanced Multilayer Systems for X-ray Optics: Quality Assessment by TEM

    Microsoft Academic Search

    D. Häussler; W. Jäger; E. Spiecker; B. Ögüt; U. Ross; J. Wiesmann; M. Störmer

    Precisely engineered systems of nanoscale multilayers are essential device components in X-ray optics for spectrometry and\\u000a in synchrotron applications. Their fabrication and optimization require processing control by high-resolution microstructure\\u000a characterization. Methods of TEM have proven to be indispensable in quantitatively assessing properties like multilayer periodicity,\\u000a orientation, or interface roughness, and in correlating the microstructure with X-ray reflectivity [1, 2].

  12. Interactions between glide dislocations and parallel interfacial dislocations in nanoscale strained layers

    Microsoft Academic Search

    F. Akasheh; H. M. Zbib; J. P. Hirth; R. G. Hoagland; A. Misra

    Plastic deformation in nanoscale multilayered structures is thought to proceed by the successive propagation of single dislocation loops at the interfaces. Based on this view, we simulate the effect of predeposited interfacial dislocation on the stress channeling stress needed to propagate a new loop parallel to existing loops. Single interfacial dislocations as well as finite parallel arrays are considered in

  13. Rewritable nanoscale oxide photodetector

    Microsoft Academic Search

    Patrick Irvin; Yanjun Ma; Daniela F. Bogorin; Cheng Cen; Chung Wung Bark; Chad M. Folkman; Chang-Beom Eom; Jeremy Levy

    2010-01-01

    Nanophotonic devices are designed to generate, guide or detect light using structures with nanoscale dimensions that are closely tied to their functionality. However, the integration of photonic nanostructures with electronic circuitry remains one of the most challenging aspects of device development. Here we report the development of rewritable nanoscale photodetectors created at the interface between LaAlO3 and SrTiO3. Nanowire junctions

  14. Thermal Conductivity of EB-PVD Thermal Barrier Coatings Evaluated by a Steady-State Laser Heat Flux Technique

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.; Nagaraj, Ben A.; Bruce, Robert W.

    2000-01-01

    The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) Zr02-8wt%Y2O3 thermal barrier coatings was determined by a steady-state heat flux laser technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long term test conditions. The thermal conductivity increase due to micro-pore sintering and the decrease due to coating micro-delaminations in the EB-PVD coatings were evaluated for grooved and non-grooved EB-PVD coating systems under isothermal and thermal cycling conditions. The coating failure modes under the high heat flux test conditions were also investigated. The test technique provides a viable means for obtaining coating thermal conductivity data for use in design, development, and life prediction for engine applications.

  15. Microstructures and mechanical properties of sputtered Cu/Cr multilayers

    SciTech Connect

    Misra, A.; Kung, H.; Mitchell, T.E.; Jervis, T.R.; Nastasi, M.

    1998-03-01

    The microstructures and mechanical properties of Cu/Cr multilayers prepared by sputtering onto {l_brace}100{r_brace} Si substrates at room temperature are presented. The films exhibit columnar grain microstructures with nanoscale grain sizes. The interfaces are planar and abrupt with no intermixing, as expected from the phase diagram. The multilayers tend to adopt a Kurdjumov-Sachs (KS) orientation relationship: {l_brace}110{r_brace}Cr // {l_brace}111{r_brace}Cu, <111>Cr // <110>Cu. The hardness of the multilayered structures, as measured by nanoindentation, increase with decreasing layer thickness for layer thicknesses ranging from 200 nm to 50 nm, whereas for lower thicknesses the hardness of the multilayers is independent of the layer thickness. Dislocation-based models are used to interpret the variation of hardness with layer periodicity. The possible effects of factors such as grain size within the layers, density and composition of films and residual stress in the multilayers are highlighted. Comparisons are made to the mechanical properties of sputtered polycrystalline Cu/Nb multilayers which, like Cu/Cr, exhibit sharp fcc/bcc interfaces with no intermixing and a KS orientation relationship, but have a small shear modulus mismatch.

  16. Transport-Controlling Nanoscale Multilayers for Biomedical Devices

    E-print Network

    Park, Jae Bum

    2012-10-19

    Area of the nanofilm Volume of liquid chamber l Length of the liquid chamber Thickness of the nanofilm Partition coefficient PSS Poly(styrene sulfonate) PAA Poly(acrylic acid) PAH Poly(allylamine hydrochloride) PLL Poly...), and PAH (c). ................................... 9 Figure 4. Molecular structures of urea (a), lactate (b), and glucose (c). ............................ 9 Figure 5. Automated experimental design to determine the diffusion coefficients of target...

  17. Investigating Deformation and Failure Mechanisms in Nanoscale Multilayer Metallic Composites

    SciTech Connect

    Zbib, Hussein M [Washington State University; Bahr, David F [Purdue University

    2014-10-22

    Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don’t permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100’s of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these tri-layer composites. CINT formed nanolaminate composites were tested in tension, with bulge testing, using nanoindentation, and using micro-compression testing to demonstrate that the tri-layer films were indeed tougher and hardened more during deformation (they got stronger as we deformed them) than equivalent bi-layers. The seven graduate students, 4 post-docs and research faculty, and the two faculty co-PI’s were able to create a collaborated computational prediction and experimental validation team to demonstrate the benefits of this class of materials to the community. The computational work crossed from atomistic to bulk simulations, and the experiments coupled form nm-scale to the mm scale; closely matching the simulations. The simulations provided viable mechanisms that explained the observed results, and new experimental results were used to push the boundaries of the simulation tools. Over the life of the 7 years of this program we proved that tri-layer nanolaminate metallic composite systems exceeded the mechanical performance of bi-layer systems if the right materials were chosen, and that the mechanism responsible for this was tied to the cross slip of dislocations. With 30 journal publications resulting from this work we have broadly disseminated this family of results to the scientific community.

  18. Nanoscale Magnetic Structure of Ferromagnet\\/Antiferromagnet Manganite Multilayers

    Microsoft Academic Search

    D. Niebieskikwiat; M. B. Salamon; L. E. Hueso; N. D. Mathur; J. A. Borchers

    2007-01-01

    Polarized Neutron Reflectometry and magnetometry measurements have been used\\u000ato obtain a comprehensive picture of the magnetic structure of a series of\\u000aLa{2\\/3}Sr{1\\/3}MnO{3}\\/Pr{2\\/3}Ca{1\\/3}MnO{3} (LSMO\\/PCMO) superlattices, with\\u000avarying thickness of the antiferromagnetic (AFM) PCMO layers (0<=t_A<=7.6 nm).\\u000aWhile LSMO presents a few magnetically frustrated monolayers at the interfaces\\u000awith PCMO, in the latter a magnetic contribution due to FM inclusions within

  19. Nanoscale Magnetic Structure of Ferromagnet\\/Antiferromagnet Manganite Multilayers

    Microsoft Academic Search

    D. Niebieskikwiat; L. E. Hueso; J. A. Borchers; N. D. Mathur; M. B. Salamon

    2007-01-01

    We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of La2\\/3Sr1\\/3MnO3\\/Pr2\\/3Ca1\\/3MnO3 (LSMO\\/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0<=tA<=7.6nm). While LSMO presents a few magnetically frustrated monolayers at the interfaces with PCMO, in the latter a magnetic contribution due to ferromagnetic (FM) inclusions within the

  20. Nanoscale Magnetic Structure of Ferromagnet\\/Antiferromagnet Manganite Multilayers

    Microsoft Academic Search

    D. Niebieskikwiat; L. E. Hueso; J. A. Borchers; N. D. Mathur; M. B. Salamon

    2007-01-01

    We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of LaSrMnO\\/PrCaMnO (LSMO\\/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0{<=}t{sub A}{<=}7.6 nm). While LSMO presents a few magnetically frustrated monolayers at the interfaces with PCMO, in the latter a magnetic contribution due to ferromagnetic (FM) inclusions

  1. Nanoscale Magnetic Structure of Ferromagnet/Antiferromagnet Manganite Multilayers

    SciTech Connect

    Niebieskikwiat, D. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Colegio de Ciencias e Ingenieria, Universidad San Francisco de Quito, Quito (Ecuador); Hueso, L. E. [Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Borchers, J. A. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Mathur, N. D. [Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Salamon, M. B. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2007-12-14

    We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/Pr{sub 2/3}Ca{sub 1/3}MnO{sub 3} (LSMO/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0{<=}t{sub A}{<=}7.6 nm). While LSMO presents a few magnetically frustrated monolayers at the interfaces with PCMO, in the latter a magnetic contribution due to ferromagnetic (FM) inclusions within the AFM matrix is maximized at t{sub A}{approx}3 nm. This enhancement of FM moment occurs at the matching between layer thickness and cluster size, implying the possibility of tuning phase separation by imposing appropriate geometrical constraints which favor the accommodation of FM nanoclusters within the ''non-FM'' material.

  2. Development and evaluation of two PVD-coated ?-titanium orthodontic archwires for fluoride-induced corrosion protection

    Microsoft Academic Search

    Vinod Krishnan; Anand Krishnan; R. Remya; K. K. Ravikumar; S. Asha Nair; S. M. A. Shibli; H. K. Varma; K. Sukumaran; K. Jyothindra Kumar

    2011-01-01

    The present research was aimed at developing surface coatings on ? titanium orthodontic archwires capable of protection against fluoride-induced corrosion. Cathodic arc physical vapor deposition PVD (CA-PVD) and magnetron sputtering were utilized to deposit thin films of titanium aluminium nitride (TiAlN) and tungsten carbide\\/carbon (WC\\/C) coatings on ? titanium orthodontic archwires. Uncoated and coated specimens were immersed in a high

  3. Review Nano and macro-structured component fabrication by electron beam-physical vapor deposition (EB-PVD)

    Microsoft Academic Search

    J. Singh; D. E. Wolfe

    2005-01-01

    The objective of this paper is to demonstrate the versatility of electron beam-physical vapor deposition (EB-PVD) technology in engineering new materials with controlled microstructure and microchemistry in the form of coatings. EB-PVD technology is being explored in forming net-shaped components for many applications including space, turbine, optical, biomedical and auto industry. Coatings are often applied on components to extend their

  4. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  5. Multilayer Insulation Material Guidelines

    NASA Technical Reports Server (NTRS)

    Finckenor, M. M.; Dooling, D.

    1999-01-01

    Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

  6. Manipulating Assembly, Disassembly and Exchange in Responsive Polyelectrolyte Multilayers

    NASA Astrophysics Data System (ADS)

    Hammond, Paula

    2008-03-01

    Polyelectrolyte multilayer assembly is based on the alternating adsorption of multilvalent positively and negatively charged species to create ionically crosslinked thin films with nanoscale control of film composition and function. We have utilized this method of assembly to manipulate ion transport, molecular transport, and electrochemical transport in these films, enabling the generation of a range of organic and organic-inorganic devices. Biological materials applications are also derived from such films, enabling their use as drug delivery devices. In each of these applications, it is desired to control interdiffusion and exchange within the multilayer systems to maintain desired function and generate isolated regions of composition and function within the z-direction of the film. Here we address these applications and means of controlling this phenomenon. Furthermore, it is desirable to induce controlled means of disassembly of these multilayer thin films. We will address a number of approaches for achieving this, including hydrolytic degradation, hydrogen bond dissociation, and controlled deconstruction on electrochemical impulse.

  7. Nanoscale Stress Measurements and Standards

    E-print Network

    Magee, Joseph W.

    Nanoscale Stress Measurements and Standards SEMICONDUCTORS Our objective is to develop accurate measurement methods for the nanoscale stress distributions and surface defects that control device performance % CAGR and 41 % US share. · Measurement of stress distributions around transistors in semiconductor

  8. High-temperature multilayers

    NASA Astrophysics Data System (ADS)

    Yulin, Sergiy; Benoit, Nicolas; Feigl, Torsten; Kaiser, Norbert

    2005-05-01

    The effect of elevated temperatures on the optical and structural stability of MoSi2/Si and Mo/C/Si/C multilayer coatings was investigated. The multilayer mirrors were designed for normal-incidence reflectivity at a wavelength of about 13.5 nm. The multilayers were deposited by dc-magnetron sputtering and subsequently annealed at temperatures of 400 °C and 500 °C for 1, 10 and 100 hours. X-ray scattering, transmission electron microscopy, atomic force microscopy and normal-incidence reflectivity measurements were used for the characterization of the multilayer structures. We achieved maximal normal-incidence reflectivities of 41.2 % and 59.6 % for as-deposited MoSi2/S and Mo/C/Si/C multilayer mirrors. While the optical properties of Mo/C/Si/C multilayers changed monotonically during annealing time at temperatures of more than 400 °C, the MoSi2/Si multilayers showed a superior thermal stability up to 500 °C. New barrier layer materials were also suggested to enhance the thermal stability of Mo/Si multilayers. Interface-engineered Mo/Si multilayer mirrors were designed to combine both a high reflectivity of more than 60 % at 13.5 nm and a superior long-term thermal stability of up to 500 °C.

  9. Physical vapor deposited titanium thin films for biomedical applications: Reproducibility of nanoscale surface roughness and microbial adhesion properties

    NASA Astrophysics Data System (ADS)

    Lüdecke, Claudia; Bossert, Jörg; Roth, Martin; Jandt, Klaus D.

    2013-09-01

    The surface topography is of great importance for the biological performance of titanium based implants since it may influence the initial adsorption of proteins, cell response, as well as microbial adhesion. A recently described technique for the preparation of titanium thin films with an adjustable surface roughness on the nanometer scale is the physical vapor deposition (PVD). The aims of this study were to statistically evaluate the reproducibility of nanorough titanium thin films prepared by PVD using an atomic force microscopy (AFM) based approach, to test the microbial adhesion in dependence of the nanoscale surface roughness and to critically discuss the parameters used for the characterization of the titanium surfaces with respect to AFM microscope settings. No statistically significant differences were found between the surface nanoroughnesses of the PVD prepared titanium thin films. With increasing surface nanoroughness, the coverage by Escherichia coli decreased and the microbial cells were increasingly patchy distributed. The calculated roughness values significantly increased with increasing AFM scan size, while image resolution and pixel density had no influence on this effect. Our study shows that PVD is a suitable tool to reproducibly prepare titanium thin films with a well-defined surface topography on the nanometer scale. These surfaces are, thus, a suitable 2D model system for studies addressing the interaction between surface nanoroughness and the biological system. First results show that surface roughness even on the very low nanometer scale has an influence on bacterial adhesion behavior. These findings give new momentum to biomaterials research and will support the development of biomaterials surfaces with anti-infectious surface properties.

  10. Functional expression and activity of the recombinant antifungal defensin PvD1r from Phaseolus vulgaris L. (common bean) seeds

    PubMed Central

    2014-01-01

    Background Defensins are basic, cysteine-rich antimicrobial peptides that are important components of plant defense against pathogens. Previously, we isolated a defensin, PvD1, from Phaseolus vulgaris L. (common bean) seeds. Results The aim of this study was to overexpress PvD1 in a prokaryotic system, verify the biologic function of recombinant PvD1 (PvD1r) by comparing the antimicrobial activity of PvD1r to that of the natural defensin, PvD1, and use a mutant Candida albicans strain that lacks the gene for sphingolipid biosynthesis to unravel the target site of the PvD1r in C. albicans cells. The cDNA encoding PvD1, which was previously obtained, was cloned into the pET-32 EK/LIC vector, and the resulting construct was used to transform bacterial cells (Rosetta Gami 2 (DE3) pLysS) leading to recombinant protein expression. After expression had been induced, PvD1r was purified, cleaved with enterokinase and repurified by chromatographic steps. N-terminal amino acid sequencing showed that the overall process of the recombinant production of PvD1r, including cleavage with the enterokinase, was successful. Additionally, modeling revealed that PvD1r had a structure that was similar to the defensin isolated from plants. Purified PvD1 and PvD1r possessed inhibitory activity against the growth of the wild-type pathogenic yeast strain C. albicans. Both defensins, however, did not present inhibitory activity against the mutant strain of C. albicans. Antifungal assays with the wild-type C. albicans strains showed morphological changes upon observation by light microscopy following growth assays. PvD1r was coupled to FITC, and the subsequent treatment of wild type C. albicans with DAPI revealed that the labeled peptide was intracellularly localized. In the mutant strain, no intracellular labeling was detected. Conclusion Our results indicate that PvD1r retains full biological activity after recombinant production, enterokinase cleavage and purification. Additionally, our results from the antimicrobial assay, the microscopic analysis and the PvD1r-FITC labeling assays corroborate each other and lead us to suggest that the target of PvD1 in C. albicans cells is the sphingolipid glucosylceramide. PMID:24690228

  11. Exploring at the Nanoscale

    NSDL National Science Digital Library

    IEEE

    2013-02-25

    This lesson focuses on how nanotechnology has impacted our society and how engineers have learned to explore the world at the nanoscale. Learners participate in hands-on activities to understand exactly how small the nanoscale is, explore how surface area changes at the nano scale, and work in teams to develop futuristic applications of nanotechnology. Specifically, teams of learners examine and measure blocks of tofu or gelatin to determine the surface area. Then they slice the blocks into smaller and smaller pieces, exposing more surfaces, and impacting the surface area. Learners also explore the size of small by comparing various items to understand the size of nano.

  12. Turning of high strength steel alloy with PVD- and CVD-coated inserts

    SciTech Connect

    Jawaid, A.; Olajire, K.A.

    1998-07-01

    PVD TiN-coated(T1) and CVD Ti(C,N)/TiC/Al{sub 2}O{sub 3}-coated(T2) inserts were used to machine a high strength low-alloy (HSLA) steel to assess their performance. The single-layer PVD-coated insert gave comparable tool life results to the triple-layer CVD-coated insert due to better coating adhesion, finer grain size and lower cobalt content. Observed active failure modes at high cutting speeds and feed rate were mainly chipping/fracture on the minor cutting edge for T1 and excessive nose wear for T2. The wear mechanisms on the former were interfacial sliding, dissolution/diffusion, and attrition wear mechanisms, while the latter wore principally by interfacial sliding and plastic deformation.

  13. EB-PVD processing of pyrochlore-structured La 2Zr 2O 7-based TBCs

    Microsoft Academic Search

    B Saruhan; P Francois; K Fritscher; U Schulz

    2004-01-01

    New ceramic thermal barrier coating (TBC) compositions superior to state-of-the-art PYSZ material are considered to overcome the problems related to phase stability and service-induced sintering within the columnar feather-like structure of current EB-PVD TBCs. Among those candidates for gas turbine applications, the pyrochlore-structure based TBCs, e.g. undoped and RE-oxide doped La2Zr2O7 offer very attractive properties. This work describes the fabrication

  14. Fabrication of TBC-armored rocket combustion chambers by EB-PVD methods and TLP assembling

    Microsoft Academic Search

    Uwe Schulz; Klaus Fritscher; Manfred Peters; Dirk Greuel; Oskar Haidn

    2005-01-01

    A thermal barrier coating (TBC) system for rocket chambers made of Cu-based high strength alloys has been developed in a pilot project in line with EB-PVD (electron-beam physical vapor deposition) technology aiming at TBC application on Cu-based walls of real rocket combustion chambers. The TBC system consists of a metallic bond coating compatible with Cu-based material and an yttria partially

  15. Effect of Bond Coat Materials on Thermal Fatigue Failure of EB-PVD Thermal Barrier Coatings

    Microsoft Academic Search

    Satoshi Yamagishi; Masakazu Okazaki; Motoki Sakaguchi; Hideaki Matsubara

    2008-01-01

    Effect of MCrAlY bond coat alloy systems on thermal fatigue failure of thermal barrier coatings (TBCs) was investigated, where the TBC specimen consisted of Ni-based superalloy IN738LC substrate, bond coat, and 8 wt.% Y2O3-stabilized ZrO2 (YSZ) top coat. The top coat was fabricated by EB-PVD method with 250 mum in thickness. Three kinds of MCrAlY alloys were studied as the

  16. Nanomechanical study of thin film nanocomposite and PVD thin films on polymer substrates for optical applications

    NASA Astrophysics Data System (ADS)

    Moghal, Jonathan; Bird, Andrew; Harris, Adrian H.; Beake, Ben D.; Gardener, Martin; Wakefield, Gareth

    2013-12-01

    The mechanical properties of ultrathin (<120 nm) films differ substantially from the bulk properties of the material and are also strongly substrate dependent. We compare the properties of two differing film systems; a high particle loading nanocomposite of silica and a multiple layer physical vapour deposition (PVD) coating by nanoindentation, nano-scratch and nano-impact followed by structural analysis. The work is undertaken on hardcoated polymer substrates and uses two types of anti-reflection coatings as test systems. The nanocomposite film comprises of a high (>50%) loading of silica nanoparticles in an inorganic binder, which demonstrates significant flex and elastic recovery whereas PVD films are subject to brittle failure even at low applied loads. Failure of the nanocomposite film, with the exception of minor plastic deformation, does not occur until the underlying substrate fails. Although the PVD film has a greater hardness than the nanocomposite, failure occurs at lower loads due to a number of toughness reducing factors including reduced modulus, modulus mismatch with the substrate and film thickness. The resistance of ultrathin films to external mechanical stresses is therefore related to a number of factors and not simply to film hardness, the most important of which are film structure and film mechanical matching to the substrate.

  17. Modular, Multilayer Perceptron

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Liu, Tsuen-Hsi

    1991-01-01

    Combination of proposed modular, multilayer perceptron and algorithm for its operation recognizes new objects after relatively brief retraining sessions. (Perceptron is multilayer, feedforward artificial neural network fully connected and trained via back-propagation learning algorithm.) Knowledge pertaining to each object to be recognized resides in subnetwork of full network, therefore not necessary to retrain full network to recognize each new object.

  18. Hybrid diffusive/PVD treatments to improve the tribological resistance of Ti-6Al-4V.

    PubMed

    Marin, E; Offoiach, R; Lanzutti, A; Regis, M; Fusi, S; Fedrizzi, L

    2014-01-01

    Titanium alloys are nowadays used for a wide range of biomedical applications thanks to their combination of high mechanical resistance, high corrosion resistance and biocompatibility. Nevertheless, the applicability of titanium alloys is sometimes limited due to their low microhardness and tribological resistance. Thus the titanium alloys cannot be successfully applied to prosthetic joint couplings. A wide range of surface treatments, in particular PVD coatings such as CrN and TiN, have been used in order to improve the tribological behaviour of titanium alloys. However, the low microhardness of the titanium substrate often results in coating failure due to cracks and delamination. For this reason, hybrid technologies based on diffusive treatments and subsequent PVD coatings may improve the overall coating resistance. In this work, conventional PVD coatings of CrN or TiCN, deposited on Titanium Grade 5, were characterized and then combined with a standard thermal diffusive nitriding treatment in order to improve the tribological resistance of the titanium alloys and avoid coating delamination. The different treatments were studied by means of scanning electron microscopy both on the sample surface and in cross-section. In-depth composition profiles were obtained using glow discharge optical emission spectrometry (GDOES) and localized energy dispersive X-ray diffraction on linear scan-lines. The microhardness and adhesion properties of the different treatments were evaluated using Vickers microhardness tests at different load conditions. The indentations were observed by means of SEM in order to evaluate delaminated areas and the crack's shape and density. The tribological behaviour of the different treatments was tested in dry conditions and in solution, in alternate pin-on-flat configuration, with a frequency of 0.5 Hz. After testing, the surface was investigated by means of stylus profilometry and SEM both on the surface and in cross-section. The standalone PVD coatings show a limited tribological resistance due to the low hardness of the substrate, which results in fractures and delamination. The combination of a diffusive process and a subsequent PVD coating shows a stronger effect in improving the tribological resistance of the substrate. PMID:24211942

  19. Nanoscale ear drum: Graphene based nanoscale sensors

    E-print Network

    Avdoshenko, Stas M; Cuniberti, Gianaurelio

    2012-01-01

    The difficulty in determining the mass of a sample increases as its size diminishes. At the nanoscale, there are no direct methods for resolving the mass of single molecules or nanoparticles and so more sophisticated approaches based on electromechanical phenomena are required. More importantly, one demands that such nanoelectromechanical techniques could provide not only information about the mass of the target molecules but also about their geometrical properties. In this sense, we report a theoretical study that illustrates in detail how graphene membranes can operate as nanoelectromechanical mass-sensor devices. Wide graphene sheets were exposed to different types and amounts of molecules and molecular dynamic simulations were employed to treat these doping processes statistically. We demonstrate that the mass variation effect and information about the graphene-molecule interactions can be inferred through dynamical response functions. Our results confirm the potential use of graphene as mass detector dev...

  20. Netlike knitting of polyelectrolyte multilayers on honeycomb-patterned substrate.

    PubMed

    Sun, Wei; Shen, Liyan; Wang, Jiaming; Fu, Ke; Ji, Jian

    2010-09-01

    The pH-amplified exponential growth layer-by-layer (LBL) self-assembly process was directly performed on honeycomb-patterned substrate for achievement of "guided patterning" of polyelectrolyte multilayers. Polyethylenimine (PEI) and poly(acrylic acid) (PAA) were used as polyanions, and their pH were carefully tuned to achieve pH-enhanced exponential growth. Guided by underlying hexagonally patterned islandlike poly(dimethylsiloxane) (PDMS) arrays, the diffusive polyelectrolytes rapidly interweaved into linear, multilayered structures distributed along the grooves between the patterned protuberate and formed a regular network of multilayered film with uniform mesh size. Netlike "knitting" of polyelectrolyte multilayers on honeycomb-patterned substrate has been realized by following this procedure. Superhydrophobic surfaces could be readily obtained after several bilayers of LBL assembly (with thermal cross-linking and surface fluorination by chemical vapor deposition), indicating that successful fabrication of functional micro- and nanoscale hierarchical structures can be achieved. Both high- and low-adhesion superhydrophobic surfaces ("petal effect" and "lotus effect") can be obtained with different bilayers of assembly, proving that different levels of nano- to microstructural hierarchy can be realized using this method. Furthermore, we were able to get topographically asymmetric, free-standing, polyelectrolyte multilayer films in the case that we performed more than eight bilayers of assembly. This research reported template-directed LBL patterning assembly for the first time. It provides a beneficial exploration for the surface patterning technique for the LBL assembly process. PMID:20684559

  1. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D. (Livermore, CA); Britten, Jerald A. (Oakley, CA); Nguyen, Hoang T. (Livermore, CA); Boyd, Robert (Livermore, CA); Shore, Bruce W. (Livermore, CA)

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  2. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  3. Preparation of a PVdF-HFP/polyethylene composite gel electrolyte with shutdown function for lithium-ion secondary battery

    NASA Astrophysics Data System (ADS)

    Liu, Xingjiang; Kusawake, Hiroaki; Kuwajima, Saburo

    In order to improve the safety of lithium-ion secondary battery, a PVdF-HFP/polyethylene (PE) composite gel electrolyte with thermal shutdown function was prepared as an internal safety device. The composite gel electrolyte consists of a PVdF-HFP polymer, PE thermoplastic resin, and 1.0 mol/dm 3 LiClO 4/PC+EC (or LiPF 6/GBL+EC) plasticizer. When the PE content is over 23 wt.%, the electrical impedance of the composite gel electrolyte can increase rapidly by several orders, around the melting point of PE (mp: 90 or 104-115°C). By the SEM observation it was found that the PE particles uniformly dispersed in the PVdF-HFP gel electrolyte could be fused and formed into a continuous film at or near the PE melting point. The continuous PE film exhibits an ability to cut off the ion diffusion between cathode and anode, thus preventing the cell from thermal runaway. Also, a three-layered film of pure PVdF-HFP gel/composite gel/pure PVdF-HFP with a higher ionic conductivity and good mechanical strength was prepared for assembling a coin-type lithium-ion cell.

  4. Mapping nanoscale light fields

    NASA Astrophysics Data System (ADS)

    Rotenberg, N.; Kuipers, L.

    2014-12-01

    The control of light fields on subwavelength scales in nanophotonic structures has become ubiquitous, driven by both curiosity and a multitude of applications in fields ranging from biosensing to quantum optics. Mapping these fields in detail is crucial, as theoretical modelling is far from trivial and highly dependent on nanoscale geometry. Recent developments of nanoscale field mapping, particularly with near-field microscopy, have not only led to a vastly increased resolution, but have also resulted in increased functionality. The phase and amplitude of different vector components of both the electric and magnetic fields are now accessible, as is the ultrafast temporal or spectral evolution of propagating pulses in nanostructures. In this Review we assess the current state-of-the-art of subwavelength light mapping, highlighting the new science and nanostructures that have subsequently become accessible.

  5. Collaboration at the Nanoscale

    NSDL National Science Digital Library

    Jennifer L. Jamison

    2009-04-01

    The Maine ScienceCorps is a project sponsored by the National Science Foundation's (NSF) Graduate Teaching Fellows in K-12 Education (GK-12 ) program. Through this program, the University of Southern Maine's (USM) virology and transmission electron microscopy (TEM) research group provides high school teachers and students in rural areas with access to the nanoscale world of viruses. This article illustrates how access to the university research community's advanced technological resources can enrich science learning in high school classrooms.

  6. Supersymmetry Across Nanoscale Heterojunction

    E-print Network

    Bagchi, B; Sinha, A

    2010-01-01

    We argue that supersymmetric transformation could be applied across the heterojunction formed by joining of two mixed semiconductors. A general framework is described by specifying the structure of ladder operators at the junction for making quantitative estimation of physical quantities. For a particular heterojunction device, we show that an exponential grading inside a nanoscale doped layer is amenable to exact analytical treatment for a class of potentials distorted by the junctions through the solutions of transformed Morse-Type potentials.

  7. Science Sampler: Nanoscale in perspective

    NSDL National Science Digital Library

    Elvis H. Cherry

    2008-04-01

    Nanoscale science is a growing field, and to appreciate the work of scientists in this field, it is important for students to understand the scale of work being done. This activity, designed to bring nanoscale into the familiar macroworld, is from a two-week workshop on nanotechnology conducted by Fisk University in Nashville, Tennessee that was sponsored by the National Center for Learning and Teaching in Nanoscale Science and Engineering (NCLT) and the National Science Foundation (NSF).

  8. Mechanical and tribological properties of PVD and PACVD wear resistant coatings

    Microsoft Academic Search

    H Meerkamm; W Fruth; T Krumpiegl; C Schaufler

    1999-01-01

    The present article reports on the mechanical characterisation and tribological properties of hard carbon based coatings (a-C, Me-C:H, a-C:H) and MoS2 coatings deposited on steel and polymer substrates. The films were deposited with PVD and PACVD deposition technique.DLC and Me-C:H coatings, such as WC-C:H or Cr-C:H, are promising for applications in fields where low friction coefficients are needed, e.g. in

  9. Acquisition and properties of wear-resistant PVD\\/CVD coatings on a hard-alloy tool

    Microsoft Academic Search

    I. V. Blinkov; V. N. Anikin; R. V. Kratokhvil; A. N. Ivanov; M. I. Petrzhik; Yu. Mikhal’ski; A. Nakonechny

    2011-01-01

    The processes of structure and phase formation during the formation of combined physical deposition (PVD)\\/chemical deposition\\u000a (CVD) coatings on a hard-alloy tool are investigated. It is shown that the formation of the Cr PVD barrier layer prevents\\u000a the formation of the ? phase with the subsequent deposition of the TiC-Ti(C,N)-TiN CVD coating. Treatment of the CVD coating\\u000a with the ion-plasma

  10. Controlling Wear on Nanoscale

    NASA Astrophysics Data System (ADS)

    D'Acunto, Mario

    One definition of wear in a tribological sense is that it is the progressive loss of mass from the operating surface of a body as a result of relative motion with another surface. Generally, tribology may be defined as the study of friction wear and lubrication, but in comparison with friction forces or lubrication methods, very little work has been done on the extremely important area of wear and surface damage. For systems consisting of common materials (metals, polymers, ceramics), there are at least four main mechanisms by which wear and surface damage can occur between solids in relative motion: abrasive-, adhesive-, chemical-, corrosive-, or fatigue-wear mechanisms. The occurrence of such different wear mechanisms involves the fundamental mechanics of molecular and supra-molecular scale. As a consequence, the understanding of surface properties on nanoscale level should be generated to also have a satisfactory knowledge of materials response on macrometer scale. Investigation of the fundamental characteristics of wear at the nanoscale is complicated by some factors and forces that acting on such scale level have not yet been addressed in the tribology of macro-systems. Since these forces are sensitive to the environment and surface condition of the specimens, it is quite difficult to determine them accurately. Further, quantification of wear is not straightforward since the amount of wear is often too small to be detected by surface-sensitive instruments. Nanowear measurements have been object of rapid development of precise measuring tools following to the introduction of scanning-probe microscopy (SPM) family. The advent of SPM family opened a new unique opportunity to study wear mechanisms on nanoscale, making possible to simulate one single asperity surface sliding on the other one and controlling many physical parameters during the contact dynamics. Further, SPM made possible to a have a direct connection between experimental data and theoretical models.

  11. Nanotribology and Nanoscale Friction

    SciTech Connect

    Guo, Yi [Stevens Institute of Technology, Hoboken, New Jersey; Qu, Zhihua [University of Central Florida, Orlando; Braiman, Yehuda [ORNL; Zhang, Zhenyu [ORNL; Barhen, Jacob [ORNL

    2008-01-01

    Tribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product (Persson, 2000). For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale friction has a technological impact in reducing energy loss in machines, in microelectromechanical systems (MEMS), and in the development of durable, low-friction surfaces and ultra-thin lubrication films.

  12. Microfluidics and Nanoscale Research Profile

    E-print Network

    Microfluidics and Nanoscale Science Research Profile Our research group is engaged in a broad range of activities in the general area of microfluidics and nanoscale science. At a primary level, our interest that when compared to macroscale tech- nology, microfluidic systems engender a number of distinct advantages

  13. Influence of EB-PVD TBC Microstructure on Thermal Barrier Coating System Performance Under Cyclic Conditions

    SciTech Connect

    Leyens, C.; Pint, B.A.; Schulz, U.; Wright, I.G.

    1999-04-12

    The lifetimes of electron beam physical vapor deposited (EB-PVD) thermal barrier coating systems (TBCs) with three different microstructures of the Y2O3-stabilized ZrO, YSZ) ceramic top layer were investigated in lh thermal cycles at 1100 and 1150°C in flowing oxygen. Single crystal alloys CMSX-4 and Rene N5 that had been coated with an EB-PVD NiCoCrAlY bond coat were chosen as substrate materials. At 1150°C all samples failed after 80-100, lh cycles, predominantly at the bond coat/alumina interface after cooling down from test temperature. The alumina scale remained adherent to the YSZ after spallation. Despite the different YSZ microstructures no clear tendency regarding differences in spallation behavior were observed at 1150°C. At 1100°C the minimum lifetime was 750 , lh cycles for CMSX-4, whereas the first Rene N5 specimen failed after 1750, lh cycles. The longest TBC lifetime on CMSX-4 substrates was 1250, lh cycles, whereas the respective Rene N5 specimens have not yet failed after 2300, lh cycles. The failure mode at 1100°C was identical to that at 115O?C, i.e. the TBC spalled off the surface exposing bare metal after cooling. Even though not all specimens have failed to date, the available results at 1100°C suggested that both, the substrate alloy chemistry and the YSZ microstructure significantly affect the spallation resistance of the TBC.

  14. Computing and fabricating multilayer models

    E-print Network

    Holroyd, Michael

    We present a method for automatically converting a digital 3D model into a multilayer model: a parallel stack of high-resolution 2D images embedded within a semi-transparent medium. Multilayer models can be produced quickly ...

  15. Nanoscale relaxation oscillator

    DOEpatents

    Zettl, Alexander K. (Kensington, CA); Regan, Brian C. (Los Angeles, CA); Aloni, Shaul (Albany, CA)

    2009-04-07

    A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

  16. Microstructural variations in Cu/Nb and Al/Nb nanometallic multilayers

    SciTech Connect

    Polyakov, M. N.; Hodge, A. M. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California 90089 (United States)] [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Courtois-Manara, E.; Wang, D.; Kuebel, C. [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany)] [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Chakravadhanula, K. [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany) [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Helmholtz Institute Ulm, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2013-06-17

    Miscible (Al/Nb) and immiscible (Cu/Nb) nanometallic multilayer systems were characterized by means of transmission electron microscopy techniques, primarily by automated crystallographic orientation mapping, which allows for the resolution of crystal structures and orientations at the nanoscale. By using this technique, distinctive Nb orientations in relation to the crystallographic state of the Al and Cu layer structures can be observed. Specifically, the Al and Cu layers were found to consist of amorphous, semi-amorphous, and crystalline regions, which affect the overall multilayer microstructure.

  17. Characterization of the PvdS-regulated promoter motif in Pseudomonas syringae pv. tomato DC3000 reveals

    E-print Network

    Myers, Chris

    Characterization of the PvdS-regulated promoter motif in Pseudomonas syringae pv. tomato DC3000S, a group IV sigma factor encoded by Pseudomonas syringae pv. tomato DC3000 (DC3000), a plant pathogen, 2002; Potvin et al., 2008). The model plant pathogen Pseudomonas syringae pv. tomato DC3000 (DC3000

  18. Application of Vickers indentation for assessment of PVD TiN coated new nonledeburitic high-speed steels

    Microsoft Academic Search

    J Richter

    2003-01-01

    The work is focused on the application of Vickers method for assessment of PVD coated high-speed steels. New grades of tailored carbide phase and commercial steels, both wrought and by powder metallurgy, were coated with titanium nitride. Indentations made at a wide range of loads were employed to obtain the coatings hardness using both theoretical models and an extrapolation method.

  19. Nanoscale Science and Engineering Center SCIENCE OF NANOSCALE SYSTEMS

    E-print Network

    Loncar, Marko

    . These nanoscale building blocks are promising for nanoelectronics and nanophotonics as well as for biosensors, graduate, and postdoctoral levels through a range of activities, including REU and RET programs

  20. Magnetic multilayer physics

    Microsoft Academic Search

    M. J. Pechan

    1994-01-01

    Microscopic magnetic systems, and especially multilayer structures, are providing a wealth of novel phenomena in condensed matter magnetism. Of particular significance are interfacial and interlayer effects. The interface between two magnetically dissimilar materials can significantly alter the bulk magnetic properties of either constituent material; and coupling of magnetic layers across relatively thick nonmagnetic interlayers are observed to have unexpectedly large

  1. Design and synthesis of bimetallic electrocatalyst with multilayered Pt-skin surfaces.

    SciTech Connect

    Wang, C.; Chi, M.; Li, D.; Strmcnik, D.; van der Vliet, D.; Wang, G.; Komanicky, V.; Chang, K.-C.; Paulikas, A. P.; Tripkovic, D.; Pearson, J.; More, K. L.; Markovic, N. M.; Stamenkovic, V. R. (Materials Science Division); (ORNL.); (Univ. of Pittsburgh)

    2011-01-01

    Advancement in heterogeneous catalysis relies on the capability of altering material structures at the nanoscale, and that is particularly important for the development of highly active electrocatalysts with uncompromised durability. Here, we report the design and synthesis of a Pt-bimetallic catalyst with multilayered Pt-skin surface, which shows superior electrocatalytic performance for the oxygen reduction reaction (ORR). This novel structure was first established on thin film extended surfaces with tailored composition profiles and then implemented in nanocatalysts by organic solution synthesis. Electrochemical studies for the ORR demonstrated that after prolonged exposure to reaction conditions, the Pt-bimetallic catalyst with multilayered Pt-skin surface exhibited an improvement factor of more than 1 order of magnitude in activity versus conventional Pt catalysts. The substantially enhanced catalytic activity and durability indicate great potential for improving the material properties by fine-tuning of the nanoscale architecture.

  2. Nanoscale laser processing and diagnostics

    Microsoft Academic Search

    David Hwang; Sang-Gil Ryu; Nipun Misra; Hojeong Jeon; Costas P. Grigoropoulos

    2009-01-01

    The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based\\u000a processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured\\u000a near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural\\u000a changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive

  3. Nanoscale Growth Twins in Sputtered Copper Films

    E-print Network

    Anderoglu, Osman

    2011-08-08

    I.1. Thin film deposition techniques ................................................... 4 I.1.1. Physical vapor deposition (PVD) ....................................... 5 I.1.2. Electrodeposition... Schematic description of electrodeposition. ............................................... 9 4 Schematic showing film growth on a substrate .......................................... 13 5 Schematic showing stages of polycrystalline film formation...

  4. Multilayer Gradient Coil Design

    PubMed

    Bowtell; Robyr

    1998-04-01

    In standard cylindrical gradient coils consisting of wires wound in a single layer, the rapid increase in coil resistance with efficiency is the limiting factor in achieving very large magnetic field gradients. This behavior results from the decrease in the maximum usable wire diameter as the number of turns is increased. By adopting a multilayer design in which the coil wires are allowed to spread out into multiple layers wound at increasing radii, a more favorable scaling of resistance with efficiency is achieved, thus allowing the design of more powerful gradient coils with acceptable resistance values. By extending the theory used to design standard cylindrical gradient coils, we have developed mathematical expressions which allow the design of multilayer coils, and the evaluation of their performance. These expressions have been used to design a four-layer, z-gradient coil of 8 mm inner diameter, which has an efficiency of 1.73 Tm-1 A-1, a resistance of 1.8 Omega, and an inductance of 50 µH. This coil produces a gradient which deviates from linearity by less than 5% within a central cylindrical region of 4.5 mm length and 4.5 mm diameter. A coil has been constructed from this design and tested in simple imaging and pulsed gradient spin echo experiments. The resulting data verify the predicted coil performance, thus demonstrating the advantages of using multilayer coils for experiments requiring very large magnetic field gradients. Copyright 1998 Academic Press. PMID:9571104

  5. Fabrication of a molecular-level multilayer film on organic polymer surfaces via chemical bonding assembly.

    PubMed

    Zhao, Hongchi; Yang, Peng; Deng, Jianping; Liu, Lianying; Zhu, Jianwu; Sui, Yuan; Lu, Jiaoming; Yang, Wantai

    2007-02-13

    A fresh multilayer film was fabricated on a molecular level and successfully tethered to the surface of a hydroxylated organic substrate via chemical bonding assembly (CBA). Sulfate anion groups (SO4-) were preintroduced onto the surface of biaxially oriented polypropylene (BOPP) films via a reference method. Upon hydrolysis of the SO4- groups, hydroxyl groups (--OH) were formed that subsequently acted as initial reagents for a series of alternate reactions with terephthalyl chloride (TPC) and bisphenol A (BPA). A stable and well-defined multilayer film was thus fabricated via the CBA method. As a result of the nanoscale multilayer fresh film being abundant with reactive groups, it is believed that the film and its fabrication method should provide a fundamental platform for further surface functionalization and direct the design of advanced materials with desired properties. PMID:17279660

  6. OPTICAL RESONANCES IN MULTILAYER STRUCTURES

    E-print Network

    Al Hanbali, Ahmad

    in a linear, homogeneous isotropic media . . 14 1.2.2 Scattering problems and transfer matrix method metamaterials . . . . . . . . . . . . . . . . . . . . 24 1.5 Thermal radiation and multilayer structures

  7. PVD Silicon Carbide as a Thin Film Packaging Technology for Antennas on LCP Substrates for Harsh Environments

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Stanton, John W.; Ponchak, George E.; Jordan, Jennifer L.; Zorman, Christian A.

    2010-01-01

    This paper describes an effort to develop a thin film packaging technology for microfabricated planar antennas on polymeric substrates based on silicon carbide (SiC) films deposited by physical vapor deposition (PVD). The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on liquid crystal polymer (LCP) substrates. The PVD SiC thin films were deposited directly onto the antennas by RF sputtering at room temperature at a chamber pressure of 30 mTorr and a power level of 300 W. The SiC film thickness is 450 nm. The return loss and radiation patterns were measured before and after the SiC-coated antennas were submerged into perchloric acid for 1 hour. No degradation in RF performance or physical integrity of the antenna was observed.

  8. A numerical study on the fatigue and rolling contact fatigue behaviour of PVD-coated steel and titanium spur gears

    Microsoft Academic Search

    Sergio Baragetti; Federico Tordini

    2011-01-01

    Thin hard coatings deposited with physical vapor deposition (PVD) can enhance both the fatigue and the rolling contact fatigue\\u000a resistance of mechanical components. In this work a cheap and fast way to evaluate the best parameter levels of coating and\\u000a bulk material is proposed. Design of Experiments (DoE) was applied to the numerical results obtained from the simulation of\\u000a meshing

  9. Development of CVD-W coatings on CuCrZr and graphite substrates with a PVD intermediate layer

    NASA Astrophysics Data System (ADS)

    Song, Jiupeng; Lian, Youyun; Lv, Yanwei; Liu, Junyong; Yu, Yang; Liu, Xiang; Yan, Binyou; Chen, Zhigang; Zhuang, Zhigang; Zhao, Ximeng; Qi, Yang

    2014-12-01

    In order to apply tungsten (W) coatings by chemical vapor deposition (CVD) for repairing or updating the plasma facing components (PFCs) of the first wall and divertor in existing or future tokomaks, where CuCrZr or graphite is the substrate material, an intermediate layer by physical vapor deposition (PVD) has been used to accommodate the interface stress due to the mismatch of thermal expansion or act as a diffusion barrier between the CVD-W coating and the substrate. The prepared CuCrZr/PVD-Cu/CVD-W sample with active cooling has passed thermal fatigue tests by electron beam with an absorbed power of 2.2 MW/m2, 50 s on/50 s off, for 100 cycles. Another graphite/PVD-Si/CVD-W sample without active cooling underwent thermal fatigue testing with an absorbed power density of 4.62 MW/m2, 5 s on/25 s off, for 200 cycles, and no catastrophic failure was found.

  10. Microstructural analyses and wear behavior of the cemented carbide tools after laser surface treatment and PVD coating

    NASA Astrophysics Data System (ADS)

    Neves, Davi; Diniz, Anselmo Eduardo; Lima, Milton Sérgio Fernandes

    2013-10-01

    Adhesion is one of the most important characteristics of coating on cutting tools. Poor coating adhesion on the tool favors fragmentation and release of hard abrasive particles between the tool and the workpiece. These particles interact with the surfaces of the tool, accelerating its wear and decreasing tool life. One possible solution is the use of laser texturing prior to coating in order to achieve a desired surface topography with enhanced adhesion properties. In the texturing, a high-frequency short-pulse laser changes surface characteristics, generating resolidified material and selective vaporization. This work evaluated the effectiveness of laser texturing in improving the substrate-coating adhesion of PVD coated cemented carbide tools. To this end, the substrates were textured with a Nd:YAG laser, in four different intensities, and then coated with a PVD TiAlN film. To ascertain the effectiveness of laser texturing, Rockwell C indentation and turning experiments were performed on both textured tools and conventional unlasered tools. The PVD coated laser-textured tool showed better performance in the indentation and turning tests than the standard tools. A comparative evaluation of tool wear mechanisms indicated that texturing did not change the wear mechanisms, but altered their importance to tool wear. The anchoring provided by the higher roughness of the textured surface increased the adhesion of the coating on the substrate, thus increasing tool life. Additionally, the chemical modification of the carbide grains due to the laser heating might be responsible for an enhanced adhesion between coating and substrate.

  11. NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH

    EPA Science Inventory

    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. Unconventional Patterning at the Nanoscale

    NSDL National Science Digital Library

    Babayan, Y.

    A team of students and professors at Northwestern University created this course as a how-to guide to many basic nanoscale patterning procedures. It is a video lab manual that will give students training in soft lithography, for example, molding. Students will also be able to synthesize, characterize, and create nanoscale devices using common, cheap materials, and some typical chemicals. Along with each procedural video, there are also tutorials to explain the meaning and purpose of each experiment. This is a valuable website for institutions that want to introduce nanopatterning to their students, but have limited resources to do so. Computers must have Quick Time installed on them before viewing these videos.

  13. A nanoscale parametric feedback oscillator.

    PubMed

    Villanueva, L Guillermo; Karabalin, Rassul B; Matheny, Matthew H; Kenig, Eyal; Cross, Michael C; Roukes, Michael L

    2011-11-01

    We describe and demonstrate a new oscillator topology, the parametric feedback oscillator (PFO). The PFO paradigm is applicable to a wide variety of nanoscale devices and opens the possibility of new classes of oscillators employing innovative frequency-determining elements, such as nanoelectromechanical systems (NEMS), facilitating integration with circuitry and system-size reduction. We show that the PFO topology can also improve nanoscale oscillator performance by circumventing detrimental effects that are otherwise imposed by the strong device nonlinearity in this size regime. PMID:22007833

  14. Center for Nanoscale Science and Technology

    National Institute of Standards and Technology Data Gateway

    NIST Center for Nanoscale Science and Technology (Program website, free access)   Currently there is no database matching your keyword search, but the NIST Center for Nanoscale Science and Technology website may be of interest. The Center for Nanoscale Science and Technology enables science and industry by providing essential measurement methods, instrumentation, and standards to support all phases of nanotechnology development, from discovery to production.

  15. Process for manufacturing multilayer capacitors

    DOEpatents

    Lauf, Robert J. (Oak Ridge, TN); Holcombe, Cressie E. (Knoxville, TN); Dykes, Norman L. (Oak Ridge, TN)

    1996-01-01

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

  16. Process for manufacturing multilayer capacitors

    SciTech Connect

    Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

    1996-01-02

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

  17. Nanoscale eletromechanical behavior

    NASA Astrophysics Data System (ADS)

    Gharbi, Mohamed

    In this dissertation, we try to address some of the questions which arise while understanding the electromechanical behavior at the nanoscale. (1) Metals exhibit a size-dependent hardening when subjected to indentation. Mechanisms for this phenomenon have been intensely researched in recent times. Does such a size-effect also exist in the electromechanical behavior of ferroelectrics? If yes, what are the operative mechanisms? Experiments on BaTiO3 indeed suggest an elastic electromechanical size-effect. We argue, through theoretical calculations and differential experiments on another non-ferroelectric piezoelectric (Quartz), that the phenomenon of flexoelectricity (as opposed to dislocation activity) is most likely responsible for our observations. (2) Using a combination of a theoretical framework and atomistic calculations, we highlight the concept of surface piezoelectricity that can be used to interpret the piezoelectricity of nanostructures. Focusing on three specific material systems (ZnO, SrTiO3 and BaTiO3), we discuss the renormalization of apparent piezoelectric behavior at small scales. In a rather interesting interplay of symmetry and surface effects, we show that nanostructures of certain non-piezoelectric materials may also exhibit piezoelectric behavior. For the case of ZnO, using a comparison with first principles calculations, we also comment on the fidelity of the widely-used core-shell interatomic potentials to capture non-bulk electro-mechanical response. (3) Building entire devices with multiple components on single nanowires will lead to the ultimate miniaturization promised by nanotechnology. The capacitance measured from a single coaxial nanowire capacitor Cu-Cu2O-C device corresponds to ˜294microF/cm2, which considerably exceeds previously reported values for metal-insulator-metal micro-capacitors and is nearly fifty times larger than what is predicted by classical electrostatics. Our quantum mechanical calculations indicate that this unusually high capacitance value is attributed to negative quantum capacitance of the dielectric-metal interface. Also, we argue through first principle calculations on Graphene-Boron Nitrate-Graphene capacitors that quantum capacitance plays a key role in decreasing the total effective capacitance.

  18. Evaluation of Osseous Integration of PVD-Silver-Coated Hip Prostheses in a Canine Model

    PubMed Central

    Hauschild, Gregor; Hardes, Jendrik; Gosheger, Georg; Blaske, Franziska; Wehe, Christoph; Karst, Uwe; Höll, Steffen

    2015-01-01

    Infection associated with biomaterials used for orthopedic prostheses remains a serious complication in orthopedics, especially tumor surgery. Silver-coating of orthopedic (mega)prostheses proved its efficiency in reducing infections but has been limited to surface areas exposed to soft tissues due to concerns of silver inhibiting osseous integration of cementless stems. To close this gap in the bactericidal capacity of silver-coated orthopedic prostheses extension of the silver-coating on surface areas intended for osseous integration seems to be inevitable. Our study reports about a PVD- (physical-vapor-deposition-) silver-coated cementless stem in a canine model for the first time and showed osseous integration of a silver-coated titanium surface in vivo. Radiological, histological, and biomechanical analysis revealed a stable osseous integration of four of nine stems implanted. Silver trace elemental concentrations in serum did not exceed 1.82 parts per billion (ppb) and can be considered as nontoxic. Changes in liver and kidney functions associated with the silver-coating could be excluded by blood chemistry analysis. This was in accordance with very limited metal displacement from coated surfaces observed by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) 12 months after implantation. In conclusion our results represent a step towards complete bactericidal silver-coating of orthopedic prostheses. PMID:25695057

  19. Effect of Hf Additions to Pt Aluminide Bond Coats on EB-PVD TBC Life

    NASA Technical Reports Server (NTRS)

    Nesbitt, James; Nagaraj, Ben; Williams, Jeffrey

    2000-01-01

    Small Hf additions were incorporated into a Pt aluminide coating during chemical vapor deposition (CVD) on single crystal RENE N5 substrates. Standard yttria-stabilized zirconia top coats were subsequently deposited onto the coated substrates by electron beam-physical vapor deposition (EB-PVD). The coated substrates underwent accelerated thermal cycle testing in a furnace at a temperature in excess of 1121 C (2050 F) (45 minute hot exposure, 15 minute cool to approximately 121 C (250 F)) until the thermal barrier coating (TBC) failed by spallation. Incorporating Hf in the bond coat increased the TBC life by slightly more than three times that of a baseline coating without added Hf. Scanning electron microscopy of the spalled surfaces indicated that the presence of the Hf increased the adherence of the thermally grown alumina to the Pt aluminide bond coat. The presence of oxide pegs growing into the coating from the thermally grown alumina may also partially account for the improved TBC life by creating a near-surface layer with a graded coefficient of thermal expansion.

  20. Effect of Bond Coat Materials on Thermal Fatigue Failure of EB-PVD Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Yamagishi, Satoshi; Okazaki, Masakazu; Sakaguchi, Motoki; Matsubara, Hideaki

    Effect of MCrAlY bond coat alloy systems on thermal fatigue failure of thermal barrier coatings (TBCs) was investigated, where the TBC specimen consisted of Ni-based superalloy IN738LC substrate, bond coat, and 8 wt.% Y2O3-stabilized ZrO2 (YSZ) top coat. The top coat was fabricated by EB-PVD method with 250 ?m in thickness. Three kinds of MCrAlY alloys were studied as the bond coat material. Employing the originally developed test equipment, thermal fatigue tests were carried out, by applying thermal cycles between 400 and 950°C in air. Special attention was paid not only to the failure life of the TBC specimen, but also the underlying failure mechanisms. The experimental results clearly demonstrated that the effect of MCrAlY bond coat alloys on the thermal fatigue life was very significant. Some discussions were made on the experimental results based on the measurements of mechanical and metallurgical properties of the bond coat alloys: i.e., elastic stiffness, thermal expansion coefficient and high temperature oxidation resistance.

  1. Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

    2014-06-01

    A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 ?m obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (?p: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

  2. Nanoscale wicking methods and devices

    NASA Technical Reports Server (NTRS)

    Zhou, Jijie (Inventor); Bronikowski, Michael (Inventor); Noca, Flavio (Inventor); Sansom, Elijah B. (Inventor)

    2011-01-01

    A fluid transport method and fluid transport device are disclosed. Nanoscale fibers disposed in a patterned configuration allow transport of a fluid in absence of an external power source. The device may include two or more fluid transport components having different fluid transport efficiencies. The components may be separated by additional fluid transport components, to control fluid flow.

  3. Nanoscale Strength Measurements and Standards

    E-print Network

    Perkins, Richard A.

    conditions. Methods to fabricate, in- house, silicon (Si) test structures with deep reactive ion etchingNanoscale Strength Measurements and Standards CERAMICS To develop new mechanical test structures methods that enable device producers in the MEMS and NEMS industries to assess, predict, and optimize

  4. Magnetic metallic multilayers

    SciTech Connect

    Hood, R.Q.

    1994-04-01

    Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces, and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons.

  5. Lipid multilayer gratings

    NASA Astrophysics Data System (ADS)

    Lenhert, Steven; Brinkmann, Falko; Laue, Thomas; Walheim, Stefan; Vannahme, Christoph; Klinkhammer, Soenke; Xu, Miao; Sekula, Sylwia; Mappes, Timo; Schimmel, Thomas; Fuchs, Harald

    2010-04-01

    The interaction of electromagnetic waves with matter can be controlled by structuring the matter on the scale of the wavelength of light, and various photonic components have been made by structuring materials using top-down or bottom-up approaches. Dip-pen nanolithography is a scanning-probe-based fabrication technique that can be used to deposit materials on surfaces with high resolution and, when carried out in parallel, with high throughput. Here, we show that lyotropic optical diffraction gratings-composed of biofunctional lipid multilayers with controllable heights between ~5 and 100 nm-can be fabricated by lipid dip-pen nanolithography. Multiple materials can be simultaneously written into arbitrary patterns on pre-structured surfaces to generate complex structures and devices, allowing nanostructures to be interfaced by combinations of top-down and bottom-up fabrication methods. We also show that fluid and biocompatible lipid multilayer gratings allow label-free and specific detection of lipid-protein interactions in solution. This biosensing capability takes advantage of the adhesion properties of the phospholipid superstructures and the changes in the size and shape of the grating elements that take place in response to analyte binding.

  6. Ultrahard Multilayer Coatings

    SciTech Connect

    Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

    1999-05-01

    We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

  7. Sensing at the nanoscale

    NASA Astrophysics Data System (ADS)

    Demming, Anna; Hierold, Christofer

    2013-11-01

    The merits of nanostructures in sensing may seem obvious, yet playing these attributes to their maximum advantage can be a work of genius. As fast as sensing technology is improving, expectations are growing, with demands for cheaper devices with higher sensitivities and an ever increasing range of functionalities and compatibilities. At the same time tough scientific challenges like low power operation, noise and low selectivity are keeping researchers busy. This special issue on sensing at the nanoscale with guest editor Christofer Hierold from ETH Zurich features some of the latest developments in sensing research pushing at the limits of current capabilities. Cheap and easy fabrication is a top priority. Among the most popular nanomaterials in sensing are ZnO nanowires and in this issue Dario Zappa and colleagues at Brescia University in Italy simplify an already cheap and efficient synthesis method, demonstrating ZnO nanowire fabrication directly onto silicon substrates [1]. Meanwhile Nicolae Barson and colleagues in Germany point out the advantages of flame spray pyrolysis fabrication in a topical review [2] and, maximizing on existing resources, researchers in Denmark and Taiwan report cantilever sensing using a US20 commercial DVD-ROM optical pickup unit as the readout source [3]. The sensor is designed to detect physiological concentrations of soluble urokinase plasminogen activator receptor, a protein associated with inflammation due to HIV, cancer and other infectious diseases. With their extreme properties carbon nanostructures feature prominently in the issue, including the demonstration of a versatile and flexible carbon nanotube strain sensor [4] and a graphene charge sensor with sensitivities of the order of 1.3 × 10-3 e Hz-1/2 [5]. The issue of patterning for sensing devices is also tackled by researchers in the US who demonstrate a novel approach for multicomponent pattering metal/metal oxide nanoparticles on graphene [6]. Changes in electrical properties are an important indicator for sensing. In search of a better understanding of these systems Zhang et al from Southern Illinois University inspect the role of Joule heating, exothermal reactions and heat dissipation in gas sensing using nanowires [7]. The mechanisms behind electrical chemical sensors are also further scrutinized in a kinetics study by Joan Ramon Morante from the University of Barcelona in Spain. 'In spite of the growing commercial success many basic issues remain still open and under discussion limiting the broad use of this technology,' he explains. He discusses surface chemical reaction kinetics and the experimental results for different representative gas molecules to gain an insight into the chemical to electrical transduction mechanisms taking place [8]. Perhaps one of the most persistent targets in sensing research is increasing the sensitivity. Gauging environmental health issues around the commercial use of nanomaterials places high demands on low-level detection and spurred a collaboration of researchers in the UK, Croatia and Canada to look into the use of particle-impact voltammetry for detecting nanoparticles in environmental media [9]. At the University of Illinois Urbana-Champaign in the US, researchers have applied wave transform analysis techniques to the oscillations of an atomic force microscopy cantilever and tailored a time-frequency-domain filter to identify the region of highest vibrational energy [10]. The approach allows them to improve the signal to noise ratio by a factor 32 on current high-performance devices. In addition, researchers in Korea report how doping NiO nanofibres can improve the sensitivity to a number of gases, including ethanol, where the response was enhanced by as much as a factor of 217.86 [11]. Biomedicine is one of the largest industries for the application of nanotechnology in sensing. Demonstrating the state of the art, researchers in China use silicon wafers decorated with gold nanoparticles for label-free detection of DNA at concentrations as low as 1-10 fM, a sensitivity comparable t

  8. Three-dimensional, flexible nanoscale field-effect transistors as localized bioprobes.

    PubMed

    Tian, Bozhi; Cohen-Karni, Tzahi; Qing, Quan; Duan, Xiaojie; Xie, Ping; Lieber, Charles M

    2010-08-13

    Nanoelectronic devices offer substantial potential for interrogating biological systems, although nearly all work has focused on planar device designs. We have overcome this limitation through synthetic integration of a nanoscale field-effect transistor (nanoFET) device at the tip of an acute-angle kinked silicon nanowire, where nanoscale connections are made by the arms of the kinked nanostructure, and remote multilayer interconnects allow three-dimensional (3D) probe presentation. The acute-angle probe geometry was designed and synthesized by controlling cis versus trans crystal conformations between adjacent kinks, and the nanoFET was localized through modulation doping. 3D nanoFET probes exhibited conductance and sensitivity in aqueous solution, independent of large mechanical deflections, and demonstrated high pH sensitivity. Additionally, 3D nanoprobes modified with phospholipid bilayers can enter single cells to allow robust recording of intracellular potentials. PMID:20705858

  9. Direct nano-scale patterning of Ag films using hard X-ray induced oxidation.

    PubMed

    Kim, Jae Myung; Lee, Su Yong; Kang, Hyon Chol; Noh, Do Young

    2015-01-01

    The morphological change of silver nano-particles (AgNPs) exposed to an intense synchrotron X-ray beam was investigated for the purpose of direct nano-scale patterning of metal thin films. AgNPs irradiated by hard X-rays in oxygen ambient were oxidized and migrated out of the illuminated region. The observed X-ray induced oxidation was utilized to fabricate nano-scale metal line patterns using sectioned WSi2/Si multilayers as masks. Lines with a width as small as 21 nm were successfully fabricated on Ag films on silicon nitride. Au/Ag nano-lines were also fabricated using the proposed method. PMID:25537602

  10. Velocity renormalization in multilayer graphene

    NASA Astrophysics Data System (ADS)

    Min, Hongki

    2013-03-01

    Multilayer graphene has recently attracted considerable attention because of its chiral electronic structure which is sensitive to stacking sequences, and its possible use as the basis of new electronic devices. Furthermore, as sample quality improves, it is expected that electron-electron interactions play a significant role which was hidden by disorder. In this talk, we study velocity renormalization in multilayer graphene due to electron-electron interactions. After analyzing velocity renormalization in the chiral two-dimensional electron gas which is a low-energy effective model of graphene systems, we discuss its implication for multilayer graphene.

  11. Multilayer Formation: Irreversible Model

    NASA Astrophysics Data System (ADS)

    Park, Stella; Mendelsohn, Jonas; Rubner, Michael; Mayes, Anne

    2002-03-01

    In previous multilayer adsorption studies [1,2], thickness variations in polyelectrolyte layers with pH changes were plotted. In these studies where both the negatively- and positively-charged polyelectrolytes -- poly(acrylic acid) and poly(allyl amine), respectively -- were adsorbed at the same pH, the layer thickness showed sharp peaks in both layers in a narrow range of pH's. Using a previously published model of irreversible adsorption [3], we calculate each layer thickness as a function of pH and molecular weight. [1] Yoo, D.; Shiratori, S.; and Rubner, M. F., Macromolecules, (1998) 31, 4309. [2] Shiratori S.; Rubner, M. F., Macromolecules, (2000) 33, 4213. [3] Park, S. Y.; Barrett, C. J.,; Rubner, M. F., and Mayes, A. M., Macromolecules, (2001) 34, 3384.

  12. Survivable paths in multilayer networks

    E-print Network

    Parandehgheibi, Marzieh

    2012-01-01

    We consider the problem of protection in multilayer networks. In single-layer net- works, a pair of disjoint paths can be used to provide protection for a source-destination pair. However, this approach cannot be directly ...

  13. Biosafe Nanoscale Pharmaceutical Adjuvant Materials

    PubMed Central

    Jin, Shubin; Li, Shengliang; Wang, Chongxi; Liu, Juan; Yang, Xiaolong; Wang, Paul C.; Zhang, Xin; Liang, Xing-Jie

    2014-01-01

    Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes. PMID:25429253

  14. Systems engineering at the nanoscale

    NASA Astrophysics Data System (ADS)

    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.

  15. Optical antennas as nanoscale resonators

    E-print Network

    Mario Agio

    2011-11-05

    Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  16. Magnetoresistance of nanoscale molecular devices.

    PubMed

    Hod, Oded; Rabani, Eran; Baer, Roi

    2006-02-01

    Affecting the current through a molecular or nanoscale junction is usually done by a combination of bias and gate voltages. Magnetic fields are less studied because nanodevices can capture only low values of the magnetic flux. We review recent work done with the aim of finding the conditions for magnetic fields to significantly affect the conductance of such junctions. The basic idea is to create narrow tunneling resonances through a molecular ring-like structure that are highly sensitive to the magnetic field. We describe a computational method that allows us to examine atomistic models of such systems and discuss several specific examples of plausible systems, such as the quantum corral, carbon nanotubes, and polycyclic aromatic hydrocarbon molecules. A unique property of the magnetic field, namely, its ability to split degenerate levels on the ring, is shown to allow prototypes of interesting new nanoscale devices, such as the three-terminal parallel logic gate. PMID:16489730

  17. Nanoscale Phenomena in Oxide Heterostructures

    NASA Astrophysics Data System (ADS)

    Sulpizio, Joseph A.; Ilani, Shahal; Irvin, Patrick; Levy, Jeremy

    2014-07-01

    Recent advances in creating complex oxide heterostructures, interfaces formed between two different transition-metal oxides, have heralded a new era of materials and physics research, enabling a uniquely diverse set of coexisting physical properties to be combined with an ever-increasing degree of experimental control. These systems have exhibited varied phenomena such as superconductivity, magnetism, and ferroelasticity, all of which are gate tunable, demonstrating their promise for fundamental discovery and technological innovation. To fully exploit this richness, it is necessary to understand and control the physics on the smallest scales, making the use of nanoscale probes essential. Using the prototypical LaAlO3/SrTiO3 interface as a guide, we explore the exciting developments in the physics of oxide-based heterostructures, with a focus on nanostructures and the nanoscale probes employed to unravel their complex behavior.

  18. Development of Production PVD-AIN Buffer Layer System and Processes to Reduce Epitaxy Costs and Increase LED Efficiency

    SciTech Connect

    Cerio, Frank

    2013-09-14

    The DOE has set aggressive goals for solid state lighting (SSL) adoption, which require manufacturing and quality improvements for virtually all process steps leading to an LED luminaire product. The goals pertinent to this proposed project are to reduce the cost and improve the quality of the epitaxial growth processes used to build LED structures. The objectives outlined in this proposal focus on achieving cost reduction and performance improvements over state-of-the-art, using technologies that are low in cost and amenable to high efficiency manufacturing. The objectives of the outlined proposal focus on cost reductions in epitaxial growth by reducing epitaxy layer thickness and hetero-epitaxial strain, and by enabling the use of larger, less expensive silicon substrates and would be accomplished through the introduction of a high productivity reactive sputtering system and an effective sputtered aluminum-nitride (AlN) buffer/nucleation layer process. Success of the proposed project could enable efficient adoption of GaN on-silicon (GaN/Si) epitaxial technology on 150mm silicon substrates. The reduction in epitaxy cost per cm{sup 2} using 150mm GaN-on-Si technology derives from (1) a reduction in cost of ownership and increase in throughput for the buffer deposition process via the elimination of MOCVD buffer layers and other throughput and CoO enhancements, (2) improvement in brightness through reductions in defect density, (3) reduction in substrate cost through the replacement of sapphire with silicon, and (4) reduction in non-ESD yield loss through reductions in wafer bow and temperature variation. The adoption of 150mm GaN/Si processing will also facilitate significant cost reductions in subsequent wafer fabrication manufacturing costs. There were three phases to this project. These three phases overlap in order to aggressively facilitate a commercially available production GaN/Si capability. In Phase I of the project, the repeatability of the performance was analyzed and improvements implemented to the Veeco PVD-AlN prototype system to establish a specification and baseline PVD-AlN films on sapphire and in parallel the evaluation of PVD AlN on silicon substrates began. In Phase II of the project a Beta tool based on a scaled-up process module capable of depositing uniform films on batches of 4”or 6” diameter substrates in a production worthy operation was developed and qualified. In Phase III, the means to increase the throughput of the PVD-AlN system was evaluated and focused primarily on minimizing the impact of the substrate heating and cooling times that dominated the overall cycle time.

  19. Characterization of PVdF-HFP polymer membranes prepared by phase inversion techniques I. Morphology and charge–discharge studies

    Microsoft Academic Search

    A. Manuel Stephan; Dale Teeters

    2003-01-01

    A novel nanoporous polymer membrane comprised of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by phase inversion techniques using two different non-solvents. The films were subjected to scanning electron microscope (SEM) and nitrogen adsorption\\/desorption analysis. The morphology and porosity of the membranes are correlated with the chemical structure of the non-solvents used. Also, nanoparticle LiCr0.01Mn1.99O4 cathode material was prepared by solid-state

  20. Localized defects in multilayer coatings

    Microsoft Academic Search

    D. G. Stearns; P. B. Mirkarimi; E. Spiller

    2004-01-01

    We present a non-linear continuum model of the growth of localized defects in multilayer coatings nucleated by particles on the substrate. The model is valid when the deposition and etch fluxes are near normal incidence so that shadowing effects are negligible. Three-dimensional simulations of defects in Mo\\/Si multilayer films nucleated by arrays of lithographically patterned particles are shown to be

  1. Nanoscale plasticity in silica glass

    SciTech Connect

    Glosli, J.N.; Boercker, D.B.; Tesar, A.; Belak, J.

    1993-10-01

    Mechanisms of nano-scale plasticity and damage initiation in silica glass is examined using molecular dynamics simulation. Computer experiments are carried out by indenting a sharp diamond-like tool, containing 4496 atoms, into a silica slab consisting of 12288 atoms. Both elastic and plastic deformation of silica is observed during nanoindentation simulation; this transition occurs at an indentation of 1.25 nm, and the calculated hardness (15GPa for 1.5 nm indentation) agrees with experiment.

  2. Nonphotolithographic nanoscale memory density prospects

    Microsoft Academic Search

    André DeHon; Seth Copen Goldstein; Philip J. Kuekes; Patrick Lincoln

    2005-01-01

    Technologies are now emerging to construct molecular-scale electronic wires and switches using bottom-up self-assembly. This opens the possibility of constructing nanoscale circuits and memories where active devices are just a few nanometers square and wire pitches may be on the order of ten nanometers. The features can be defined at this scale without using photolithography. The available assembly techniques have

  3. SI System and Nanoscale Science

    NSDL National Science Digital Library

    This lesson, presented by the National Nanotechnology Infrastructure Network, covers the metric system. Students will explore the use of the metric system in the activities, and also "read the How Stuff Works article –“How Nanotechnology Works” and answer questions about the article. Further connections of size and the nanoscale can be found in the Resources at the end of the unit."  This activity will take two 50 minute classroom sessions. Two Teacher Preparation Guides and Student Guides are included. 

  4. Spinning light on the nanoscale.

    PubMed

    Sun, Jingbo; Wang, Xi; Xu, Tianboyu; Kudyshev, Zhaxylyk A; Cartwright, Alexander N; Litchinitser, Natalia M

    2014-05-14

    Light beams with orbital angular momentum have significant potential to transform many areas of modern photonics from imaging to classical and quantum communication systems. We design and experimentally demonstrate an ultracompact array of nanowaveguides with a circular graded distribution of channel diameters that coverts a conventional laser beam into a vortex with an orbital angular momentum. The proposed nanoscale beam converter is likely to enable a new generation of on-chip or all-fiber structured light applications. PMID:24697576

  5. Interface-engineered multilayer mirrors

    NASA Astrophysics Data System (ADS)

    Yulin, Sergiy; Benoit, Nicolas; Feigl, Torsten; Kaiser, Norbert

    2005-09-01

    Most applications of Mo/Si multilayer optics in EUVL require a high normal incidence reflectivity. Using dc magnetron sputtering we achieved R = 68.8 % @ ? = 13.5 nm. Different interface-engineered Mo/X/Si/X multilayers with maximum reflectivity of 69.6 % at 13.5 nm were developed. These new multilayer mirrors consist of molybdenum and sili-con layers separated by different interdiffusion barriers (X = C and SiC). Microstructure and optical properties of the multilayers have been investigated by small and large angle Cu-K? scattering, AFM and characterized by EUV reflectometry. A concept for material selection, thickness optimization of interdiffusion barriers and perspectives for their wide application in imaging EUVL optics will be discussed. Some applications of multilayer mirrors in EUVL require not only the highest possible normal incidence reflectivity but also a long-term and thermal stability at the operating temperatures. The Mo/C/Si/C interface-engineered were optimized in terms of high peak reflectivity at a wavelength near 13.5 nm (Rp >= 60.0 %) and broad operating temperature range (T = 20 - 500°C). The best results were obtained with 0.8 nm thickness of carbon interlayers on both interfaces. Annealing in vacuum was carried out at elevated temperatures up to 650 °C for up to 100 hours. The combination of good optical properties and high thermal stability of interface - engineered Mo/C/Si/C multilayer mirrors underlines their potential for their use in EUVL optics.

  6. Artificial multilayers and nanomagnetic materials

    PubMed Central

    SHINJO, Teruya

    2013-01-01

    The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author’s studies are described. (1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism. (2) Preparation and characterization of metallic multilayers with artificial superstructures. (3) Giant magnetoresistance (GMR) effect in magnetic multilayers. (4) Novel properties of nanostructured ferromagnetic thin films (dots and wires). A subject of particular interest in the author’s research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author’s research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint. PMID:23391605

  7. Nanoscale laser processing and diagnostics

    NASA Astrophysics Data System (ADS)

    Hwang, David; Ryu, Sang-Gil; Misra, Nipun; Jeon, Hojeong; Grigoropoulos, Costas P.

    2009-08-01

    The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive (ablation), additive (chemical vapor deposition), crystallization, and electric, magnetic activation. In the context of nanoscale diagnostics, optical-near-field-ablation-induced plasma emission was utilized for chemical species analysis by laser-induced breakdown spectroscopy. Furthermore, optical-near-field irradiation greatly improved sensitivity and reliability of electrical conductance atomic force microscopy enabling characterization of electron tunneling through the oxide shell on silicon nanowires. Efficient in-situ monitoring greatly benefits optical-near-field processing. Due to close proximity of the probe tip with respect to the sample under processing, frequent degradation of the probe end occurs leading to unstable processing conditions. Optical-fiber-based probes have been coupled to a dual-beam (scanning electron microscopy and focused ion beam) system in order to achieve in-situ monitoring and probe repair.

  8. Nanoscale Science and Engineering Center

    NSDL National Science Digital Library

    With support from the National Science Foundation, the Nanoscale Science and Engineering Center (NSEC) brings together researchers from Harvard University, the Massachusetts Institute of Technology, the University of California, Santa Barbara and the Museum of Science in Boston with participation by Delft University of Technology (Netherlands), the University of Basel (Switzerland), the University of Tokyo (Japan), and Brookhaven, Oak Ridge and Sandia National Laboratories "to construct novel electronic and magnetic devices with nanoscale sizes and understand their behavior, including quantum phenomena." The Center's main activities include research, education, and public outreach. The website lists the group's overlapping interdisciplinary research areas as Synthesis and Growth of Nanoscale Structures; Imaging Electrons inside Nanostructures; and Spins and Charges in Coherent Electronics. The links section provides information on NCES nanotechnology educational activities as well as other online resources and information on upcoming conferences in nanotechnology. The Highlights section provides just an overview of recently published research, but some of the websites for individual participants include articles and conference papers. The Annual Report also reviews recent activities and research from NSEC.

  9. Nanoscale directional motion towards regions of stiffness.

    PubMed

    Chang, Tienchong; Zhang, Hongwei; Guo, Zhengrong; Guo, Xingming; Gao, Huajian

    2015-01-01

    How to induce nanoscale directional motion via some intrinsic mechanisms pertaining to a nanosystem remains a challenge in nanotechnology. Here we show via molecular dynamics simulations that there exists a fundamental driving force for a nanoscale object to move from a region of lower stiffness toward one of higher stiffness on a substrate. Such nanoscale directional motion is induced by the difference in effective van der Waals potential energy due to the variation in stiffness of the substrate; i.e., all other conditions being equal, a nanoscale object on a stiffer substrate has lower van der Waals potential energy. This fundamental law of nanoscale directional motion could lead to promising routes for nanoscale actuation and energy conversion. PMID:25615480

  10. Junior Research Seminar: Nanoscale Patterning and Systems

    NSDL National Science Digital Library

    Odom, Teri W.

    Teri W. Odom, professor at Northwestern University, offers this course on Nanoscale Patterning and Systems. The research conducted through the course enables students to design and perform nanoscale patterning experiments with scanning probe lithography and bench-top fabrication techniques. The basic goals of the course are to help students understand current problems in nanoscale science and technology, perform bench-top nanoscale experiments, and use scanning probe techniques for patterning nanoscale features. To that end, this website offers a detailed syllabus explaining major concepts and breaking down the overall explanation of nanoscale patterning and systems, which students could use for better comprehension of nanotechnological concepts and instructors could use to help augment their own class materials.

  11. Nanoscale Physics The Wiess School of Natural Sciences

    E-print Network

    Richards-Kortum, Rebecca

    of nanostructures, quantum nanotechnology, nanoscale imaging.Thisprogramcombinesastrongcomponentinquantumtheory,whichgoverns the behavior of systems at the nanoscale, with the study of practical nano at the Nanoscale Spring Semester Elective NSCI 501 Professional Master's Seminar PHYS 534 Nanostructures

  12. Development and evaluation of two PVD-coated ?-titanium orthodontic archwires for fluoride-induced corrosion protection.

    PubMed

    Krishnan, Vinod; Krishnan, Anand; Remya, R; Ravikumar, K K; Nair, S Asha; Shibli, S M A; Varma, H K; Sukumaran, K; Kumar, K Jyothindra

    2011-04-01

    The present research was aimed at developing surface coatings on ? titanium orthodontic archwires capable of protection against fluoride-induced corrosion. Cathodic arc physical vapor deposition PVD (CA-PVD) and magnetron sputtering were utilized to deposit thin films of titanium aluminium nitride (TiAlN) and tungsten carbide/carbon (WC/C) coatings on ? titanium orthodontic archwires. Uncoated and coated specimens were immersed in a high fluoride ion concentration mouth rinse, following a specially designed cycle simulating daily use. All specimens thus obtained were subjected to critical evaluation of parameters such as electrochemical corrosion behaviour, surface analysis, mechanical testing, microstructure, element release, and toxicology. The results confirm previous research that ? titanium archwires undergo a degradation process when in contact with fluoride mouth rinses. The study confirmed the superior nature of the TiAlN coating, evident as many fewer changes in properties after fluoride treatment when compared with the WC/C coating. Thus, coating with TiAlN is recommended in order to reduce the corrosive effects of fluorides on ? titanium orthodontic archwires. PMID:21111072

  13. Design of radiation resistant metallic multilayers for advanced nuclear systems

    SciTech Connect

    Zhernenkov, Mikhail, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Gill, Simerjeet, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Ecker, Lynne [Brookhaven National Laboratory, Upton, New York 11973 (United States); Baldwin, J. Kevin; Misra, Amit [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Demkowicz, M. J. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-06-16

    Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.

  14. Nanocomposite metal amorphous-carbon thin films deposited by hybrid PVD and PECVD technique.

    PubMed

    Teixeira, V; Soares, P; Martins, A J; Carneiro, J; Cerqueira, F

    2009-07-01

    Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving adhesion and compatibility with substrates. In this work new nanocomposite coatings with improved toughness based in nanocrystalline phases of metals and ceramics embedded in amorphous carbon matrix are being developed within the frame of a research project: nc-MeNxCy/a-C(Me) with Me = Mo, Si, Al, Ti, etc. Carbide forming metal/carbon (Me/C) composite films with Me = Mo, W or Ti possess appropriate properties to overcome the limitation of pure DLC films. These novel coating architectures will be adopted with the objective to decrease residual stress, improve adherence and fracture toughness, obtain low friction coefficient and high wear-resistance. Nanocomposite DLC's films were deposited by hybrid technique using a PVD-Physically Vapor Deposition (magnetron sputtering) and Plasma Enhanced Chemical Vapor Deposition (PECVD), by the use of CH4 gas. The parameters varied were: deposition time, substrate temperature (180 degrees C) and dopant (Si + Mo) of the amorphous carbon matrix. All the depositions were made on silicon wafers and steel substrates precoated with a silicon inter-layer. The characterisation of the film's physico-mechanical properties will be presented in order to understand the influence of the deposition parameters and metal content used within the a-C matrix in the thin film properties. Film microstructure and film hybridization state was characterized by Raman Spectroscopy. In order to characterize morphology SEM and AFM will be used. Film composition was measured by Energy-Dispersive X-ray analysis (EDS) and by X-ray photoelectron spectroscopy (XPS). The contact angle for the produced DLC's on silicon substrates were also measured. Thin film adherence was studied by micro-scratch test. Residual stresses in the produced coatings will be analysed by bending technique. PMID:19916409

  15. Multilayer perceptron for nonlinear programming.

    SciTech Connect

    Reifman, J.; Feldman, E. E.; Reactor Analysis

    2002-08-01

    A new method for solving nonlinear programming problems within the framework of a multilayer neural network perceptron is proposed. The method employs the Penalty Function method to transform a constrained optimization problem into a sequence of unconstrained optimization problems and then solves the sequence of unconstrained optimizations of the transformed problem by training a series of multilayer perceptrons. The neural network formulation is represented in such a way that the multilayer perceptron prediction error to be minimized mimics the objective function of the unconstrained problem, and therefore, the minimization of the objective function for each unconstrained optimization is attained by training a single perceptron. The multilayer perceptron allows for the transformation of problems with two-sided bounding constraints on the decision variables x, e.g., a{<=}x{sub n}{<=}b, into equivalent optimization problems in which these constraints do not explicitly appear. Hence, when these are the only constraints in the problem, the transformed problem is constraint free (i.e., the transformed objective function contains no penalty terms) and is solved by training a multilayer perceptron only once. In addition, we present a new Penalty Function method for solving nonlinear programming problems that is parameter free and guarantees that feasible solutions are obtained when the optimal solution is on the boundary of the feasible region. Simulation results, including an example from operations research, illustrate the proposed methods.

  16. NONLINEAR CHANNEL EQUALIZATION USING MULTILAYER PERCEPTRONS WITH

    E-print Network

    Slatton, Clint

    NONLINEAR CHANNEL EQUALIZATION USING MULTILAYER PERCEPTRONS WITH INFORMATION-THEORETIC CRITERION perceptron scheme trained with this information theoretic criterion to the problem of nonlinear channel performance and complexity. The idea of using multilayer perceptrons (MLP) has existed in the literature

  17. Multi-layer micro/nanofluid devices with bio-nanovalves

    DOEpatents

    Li, Hao; Ocola, Leonidas E.; Auciello, Orlando H.; Firestone, Millicent A.

    2013-01-01

    A user-friendly multi-layer micro/nanofluidic flow device and micro/nano fabrication process are provided for numerous uses. The multi-layer micro/nanofluidic flow device can comprise: a substrate, such as indium tin oxide coated glass (ITO glass); a conductive layer of ferroelectric material, preferably comprising a PZT layer of lead zirconate titanate (PZT) positioned on the substrate; electrodes connected to the conductive layer; a nanofluidics layer positioned on the conductive layer and defining nanochannels; a microfluidics layer positioned upon the nanofluidics layer and defining microchannels; and biomolecular nanovalves providing bio-nanovalves which are moveable from a closed position to an open position to control fluid flow at a nanoscale.

  18. Controlling Magnetism at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Wong, Jared Jue

    In this thesis, we look at controlling the magnetic properties at the nano-scale in single crystal thin film through structural modifications and external static electric fields (i.e. magnetoelectric effects). The first part of the thesis focuses on changing the magnetic properties in thin films through sample structure modifications. The other half focuses on using static electric fields to tune the magnetic properties within magnetic thin films. We show that the magnetic anisotropy can be changes through the application of static electric fields. Most interestingly though, we find that the phase transition in magnetite can be tuned with electric fields leading to an enhanced magentoelectric effect.

  19. Young's equation at the nanoscale.

    PubMed

    Seveno, David; Blake, Terence D; De Coninck, Joël

    2013-08-30

    In 1805, Thomas Young was the first to propose an equation to predict the value of the equilibrium contact angle of a liquid on a solid. Today, the force exerted by a liquid on a solid, such as a flat plate or fiber, is routinely used to assess this angle. Moreover, it has recently become possible to study wetting at the nanoscale using an atomic force microscope. Here, we report the use of molecular-dynamics simulations to investigate the force distribution along a 15 nm fiber dipped into a liquid meniscus. We find very good agreement between the measured force and that predicted by Young's equation. PMID:24033049

  20. Electronic transport in nanoscale structures

    NASA Astrophysics Data System (ADS)

    Lagerqvist, Johan

    In this dissertation electronic transport in nanoscale structures is discussed. An expression for the shot noise, a fluctuation in current due to the discreteness of charge, is derived directly from the wave functions of a nanoscale system. Investigation of shot noise is of particular interest due to the rich fundamental physics involved. For example, the study of shot noise can provide fundamental insight on the nature of electron transport in a nanoscale junction. We report calculations of the shot noise properties of parallel wires in the regime in which the interwire distance is much smaller than the inelastic mean free path. The validity of quantized transverse momenta in a nanoscale structure and its effect on shot noise is also discussed. We theoretically propose and show the feasibility of a novel protocol for DNA sequencing based on the electronic signature of single-stranded DNA while it translocates through a nanopore. We find that the currents for the bases are sufficiently different to allow for efficient sequencing. Our estimates reveal that sequencing of an entire human genome could be done with very high accuracy in a matter of hours, e.g., orders of magnitude faster than present techniques. We also find that although the overall magnitude of the current may change dramatically with different detection conditions, the intrinsic distinguishability of the bases is not significantly affected by pore size and transverse field strength. Finally, we study the ability of water to screen charges in nanopores by using all-atom molecular dynamics simulations coupled to electrostatic calculations. Due to the short length scales of the nanopore geometry and the large local field gradient of a single ion, the energetics of transporting an ion through the pore is strongly dependent on the microscopic details of the electric field. We show that as long as the pore allows the first hydration shell to stay intact, e.g., ˜6 nearby water molecules, the electric field of the ion can be well screened. We also discuss the consequences of the formation of hydration layers and of the discrete nature of polarization at atomic length scales for the applicability of continuum dielectric models.

  1. Reducing virulence of the human pathogen Burkholderia by altering the substrate specificity of the quorum-quenching acylase PvdQ

    PubMed Central

    Koch, Gudrun; Nadal-Jimenez, Pol; Reis, Carlos R.; Muntendam, Remco; Bokhove, Marcel; Melillo, Elena; Dijkstra, Bauke W.; Cool, Robbert H.; Quax, Wim J.

    2014-01-01

    The use of enzymes to interfere with quorum sensing represents an attractive strategy to fight bacterial infections. We used PvdQ, an effective quorum-quenching enzyme from Pseudomonas aeruginosa, as a template to generate an acylase able to effectively hydrolyze C8-HSL, the major communication molecule produced by the Burkholderia species. We discovered that the combination of two single mutations leading to variant PvdQL?146W,F?24Y conferred high activity toward C8-HSL. Exogenous addition of PvdQL?146W,F?24Y dramatically decreased the amount of C8-HSL present in Burkholderia cenocepacia cultures and inhibited a quorum sensing-associated phenotype. The efficacy of this PvdQ variant to combat infections in vivo was further confirmed by its ability to rescue Galleria mellonella larvae upon infection, demonstrating its potential as an effective agent toward Burkholderia infections. Kinetic analysis of the enzymatic activities toward 3-oxo-C12-L-HSL and C8-L-HSL corroborated a substrate switch. This work demonstrates the effectiveness of quorum-quenching acylases as potential novel antimicrobial drugs. In addition, we demonstrate that their substrate range can be easily switched, thereby paving the way to selectively target only specific bacterial species inside a complex microbial community. PMID:24474783

  2. Structural and chemical investigations of CBD-and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells

    E-print Network

    Romeo, Alessandro

    (In,Ga)Se2 (CIGS) can be obtained using CdS buffer layers grown by chemical bath deposition (CBD; Chemical bath deposition; CdS buffer 1. Introduction The highest efficiencies for thin film solar cellsStructural and chemical investigations of CBD- and PVD-CdS buffer layers and interfaces in Cu

  3. Determination of mechanical properties of electron beam-physical vapor deposition-thermal barrier coatings (EB-PVD-TBCs) by means of nanoindentation and impact testing

    Microsoft Academic Search

    K.-D Bouzakis; A Lontos; N Michailidis; O Knotek; E Lugscheider; K Bobzin; A Etzkorn

    2003-01-01

    EB-PVD-zirconia coatings are well known as thermal barrier coating materials for gas turbine applications. Using these materials, the gas turbine can work at higher temperatures, and thus the turbine efficiency increases. Due to the fact that not only the turbine efficiency, but also its reliability is a very important issue, prediction of the lifetime of thermal barrier coatings by assessment

  4. Duplex Treatment of Tools and Components: Previous or Subsequent Electron Beam Hardening of Thermochemically-Treated and PVD Hard-Coated Steels for Tools and Components

    Microsoft Academic Search

    Gundis Sacher; Rolf Zenker; Heinz-Joachim Spies

    2009-01-01

    The tribological properties of tools and components are improved by wear resistant coatings deposited by thermochemical processing (nitriding, nitrocarburizing) or physical vapor deposition (PVD) technologies. The properties gradient between the very hard and brittle layer and the soft, ductile, but hardenable matrix material can be significantly improved by previous or subsequent electron beam hardening (EBH). The hardness of matrix material

  5. Oxygen Detection via Nanoscale Optical Indicators

    E-print Network

    Ghosh, Ruby N.

    Oxygen Detection via Nanoscale Optical Indicators Ruby N. Ghosh Dept. of Physics Michigan State University East Lansing, MI, USA weekschr@msu.edu Abstract--Oxygen plays a ubiquitous role in terrestrial developed an optical technique for monitoring oxygen in both gas and liquid phases utilizing nanoscale metal

  6. Thermal simulation techniques for nanoscale transistors

    Microsoft Academic Search

    Jeremy A. Rowlette; Eric Pop; Sanjiv Sinha; Mathew Panzer; Kenneth E. Goodson

    2005-01-01

    Thermal simulations are important for advanced electronic sys- tems at multiple length scales. A major challenge involves electro- thermal phenomena within nanoscale transistors, which exhibit nearly ballistic transport both for electrons and phonons. The ther- mal device behavior can influence both the mobility and the leakage currents. We discuss recent advances in modeling coupled electron- phonon transport in future nanoscale

  7. Nanoscale molecular-switch crossbar circuits

    Microsoft Academic Search

    Yong Chen; Gun-Young Jung; Douglas A. A. Ohlberg; Xuema Li; Duncan R. Stewart; Jan O. Jeppesen; Kent A. Nielsen; J. Fraser Stoddart; R. Stanley Williams

    2003-01-01

    Molecular electronics offer an alternative pathway to construct nanoscale circuits in which the critical dimension is naturally associated with molecular sizes. We describe the fabrication and testing of nanoscale molecular-electronic circuits that comprise a molecular monolayer of [2]rotaxanes sandwiched between metal nanowires to form an 8 × 8 crossbar within a 1 µm2 area. The resistance at each cross point

  8. Nanoscale Material Approaches to Thermoelectric Energy Conversion

    Microsoft Academic Search

    Rama Venkatasubramanian

    2009-01-01

    Nanoscale material approaches -- superlattices, nano dots and second phase nano-inclusions -- have become the dominant approach to enhancing the figure of merit (ZT) in thermoelectric materials for various energy conversion applications. The primary mechanism for improvement has been the significant reduction in lattice thermal conductivity through phonon scattering processes in nanoscale materials, which are not fully understood, without affecting

  9. Unfolding single- and multilayers

    NASA Astrophysics Data System (ADS)

    Llorens, Maria-Gema; Bons, Paul D.; Griera, Albert; Gomez-Rivas, Enrique

    2014-05-01

    When planar structures (e.g. sedimentary layers, veins, dykes, cleavages, etc.) are subjected to deformation, they have about equal chances to be shortened or stretched. The most common shortening and stretching structures are folds and boudinage, respectively. However, boudinage requires additional deformation mechanisms apart from viscous flow, like formation of fractures or strain localization. When folded layers are subjected to extension, they could potentially unfold back to straight layers. Although probably not uncommon, this would be difficult to recognize. Open questions are whether folded layers can unfold, what determines their mechanical behaviour and how we can recognize them in the field. In order to approach these questions, we present a series of numerical experiments that simulate stretching of previously folded single- and multi-layers in simple shear, using the two dimensional numerical modelling platform ELLE, including the finite element module BASIL that calculates viscous deformation. We investigate the parameters that affect a fold train once it rotates into the extensional field. The results show that the unfolding process strongly depends on the viscosity contrast between the layer and matrix (Llorens et al., 2013). Layers do not completely unfold when they experience softening before or during the stretching process or when other neighbouring competent layers prevent them from unfolding. The foliation refraction patterns are the main indicators of unfolded folds. Additionally, intrafolial folds and cusp-like folds adjacent to straight layers, as well as variations in fold amplitudes and limb lengths of irregular folds can also be used as indicators of stretching of a layer after shortening and folding. References: Llorens, M-.G., Bons, P.D., Griera, A. and Gomez-Rivas, E. 2013. When do folds unfold during progressive shear?. Geology, 41, 563-566.

  10. Patterning of magnetic thin films and multilayers using nanostructured tantalum gettering templates.

    PubMed

    Qiu, Wenlan; Chang, Long; Lee, Dahye; Dannangoda, Chamath; Martirosyan, Karen; Litvinov, Dmitri

    2015-03-25

    This work demonstrates that a nonmagnetic thin film of cobalt oxide (CoO) sandwiched between Ta seed and capping layers can be effectively reduced to a magnetic cobalt thin film by annealing at 200 °C, whereas CoO does not exhibit ferromagnetic properties at room temperature and is stable at up to ?400 °C. The CoO reduction is attributed to the thermodynamically driven gettering of oxygen by tantalum, similar to the exothermic reduction-oxidation reaction observed in thermite systems. Similarly, annealing at 200 °C of a nonmagnetic [CoO/Pd]N multilayer thin film sandwiched between Ta seed and Ta capping layers results in the conversion into a magnetic [Co/Pd]N multilayer, a material with perpendicular magnetic anisotropy that is of interest for magnetic data storage applications. A nanopatterning approach is introduced where [CoO/Pd]N multilayers is locally reduced into [Co/Pd]N multilayers to achieve perpendicular magnetic anisotropy nanostructured array. This technique can potentially be adapted to nanoscale patterning of other systems for which thermodynamically favorable combination of oxide and gettering layers can be identified. PMID:25761738

  11. Charge-dependent transport switching of single molecular ions in a weak polyelectrolyte multilayer.

    PubMed

    Tauzin, Lawrence J; Shuang, Bo; Kisley, Lydia; Mansur, Andrea P; Chen, Jixin; de Leon, Al; Advincula, Rigoberto C; Landes, Christy F

    2014-07-22

    The tunable nature of weak polyelectrolyte multilayers makes them ideal candidates for drug loading and delivery, water filtration, and separations, yet the lateral transport of charged molecules in these systems remains largely unexplored at the single molecule level. We report the direct measurement of the charge-dependent, pH-tunable, multimodal interaction of single charged molecules with a weak polyelectrolyte multilayer thin film, a 10 bilayer film of poly(acrylic acid) and poly(allylamine hydrochloride) PAA/PAH. Using fluorescence microscopy and single-molecule tracking, two modes of interaction were detected: (1) adsorption, characterized by the molecule remaining immobilized in a subresolution region and (2) diffusion trajectories characteristic of hopping (D ? 10(-9) cm(2)/s). Radius of gyration evolution analysis and comparison with simulated trajectories confirmed the coexistence of the two transport modes in the same single molecule trajectories. A mechanistic explanation for the probe and condition mediated dynamics is proposed based on a combination of electrostatics and a reversible, pH-induced alteration of the nanoscopic structure of the film. Our results are in good agreement with ensemble studies conducted on similar films, confirm a previously-unobserved hopping mechanism for charged molecules in polyelectrolyte multilayers, and demonstrate that single molecule spectroscopy can offer mechanistic insight into the role of electrostatics and nanoscale tunability of transport in weak polyelectrolyte multilayers. PMID:24960617

  12. Electrochemical properties of multilayer film assembled by layer-by-layer adsorption of redox polymer

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Zheng, Haitao; Liu, Shiyang; Liu, Pu; Zhou, Jingli; Suye, Shin-ichiro

    2009-07-01

    A redox polymer, poly(ethylenimine)ferrocene (PEI-Fc) was prepared by attaching electroactive ferrocene groups to the backbone of a water soluble, biocompatible polyelectrolyte, poly(ethylenimine), and multilayer film composed of polystyrenesulfonate sodium (PSS) and PEI-Fc was prepared by alternate layer-by-layer (LBL) self-assembly adsorption technique based on the electrostatic force between the opposite charges carried by these two polymers. UV-Vis spectra was used to monitor the LBL process, and the thickness and immobilization amount of each layer were characterized by quartz crystal microbalance (QCM), which showed the formation of nano-scale multilayer structure and linear mass increase dependent on the alternate adsorption cycles. The electrochemical properties of the PEI-Fc/PSS multilayer film modified gold electrode were investigated by cyclic voltammetry. It was observed clearly that the electrochemical properties of this multilayer film were strongly dependent on the layer number and the ferrocene content in PEI-Fc. The electrochemical kinetic was analyzed based on a general model for surface process, and the experimental data fitted well with that evaluated from the above model. This redox polymer showed potential for the construction of reagentless biosensor.

  13. Modeling strategies for polyelectrolyte multilayers

    NASA Astrophysics Data System (ADS)

    Cerdà, J. J.; Qiao, B.; Holm, Ch.

    2009-10-01

    The present article will give a short overview about the sparse attempts to model films made up by alternating layers of polyanions and polycations, called polyelectrolyte multilayers. First, we will review the current theoretical understanding of the field, followed by the description of the current modeling strategies,with a stress on pointing out their shortcomings. We then report some results of our our recent attempts to model the structure and dynamics of polyelectrolyte multilayers. We present two approaches: one deals with coarse-grained bead-spring models within a dielectric continuum solvent, and in the other attempt we try to infer the important microscopic interactions via a fully atomistic treatment of small oligomeric polyelectrolytes. We finally give an outlook and discuss possible extensions towards a more realistic modeling of polyelectrolyte multilayers.

  14. Extrusion of multilayer superconductor coils

    SciTech Connect

    Dorris, S.E.; Dusek, J.T.; Lanagan, M.T.; Picciolo, J.J.; Singh, S.P.; Creech, J.E.; Poeppel, R.B. (Materials and Components Technology Div., Argonne National Lab., Argonne, IL (United States))

    1991-04-01

    This paper describes bulk processes that have been applied to the fabrication of multilayer superconductor coils from the YBa[sub 2]Cu[sub 3]O[sub x] (YBCO) superconductor. In particular, three important aspects of fabricating multilayer YBCO coils are discussed. First is a discussion of the properties of Y[sub 2]BaCuO[sub 5] (211) that make it a suitable insulator for coating YBCO and a description of how the coating is applied in a continuous extrusion process. Second is a description of improvements in the mechanical properties of YBCO that result from the addition of Ag as a second phase and a discussion of the importance of these additions during the firing of multilayer coils. Third, and perhaps most important, is the description of the heat treatment of the coils.coils.

  15. Structural reducibility of multilayer networks.

    PubMed

    De Domenico, Manlio; Nicosia, Vincenzo; Arenas, Alexandre; Latora, Vito

    2015-01-01

    Many complex systems can be represented as networks consisting of distinct types of interactions, which can be categorized as links belonging to different layers. For example, a good description of the full protein-protein interactome requires, for some organisms, up to seven distinct network layers, accounting for different genetic and physical interactions, each containing thousands of protein-protein relationships. A fundamental open question is then how many layers are indeed necessary to accurately represent the structure of a multilayered complex system. Here we introduce a method based on quantum theory to reduce the number of layers to a minimum while maximizing the distinguishability between the multilayer network and the corresponding aggregated graph. We validate our approach on synthetic benchmarks and we show that the number of informative layers in some real multilayer networks of protein-genetic interactions, social, economical and transportation systems can be reduced by up to 75%. PMID:25904309

  16. Perfect absorption in graphene multilayers

    NASA Astrophysics Data System (ADS)

    Nefedov, Igor S.; Valaginnopoulos, Constantinos A.; Melnikov, Leonid A.

    2013-11-01

    We demonstrate that 100% light absorption can be achieved in a graphene-based hyperbolic metamaterial, consisting of periodically arranged graphene layers which are tilted with respect to the interface. The geometrical parameters of the multilayered structure and the chemical potential of graphene are chosen in such a way that the in-plane relative effective permittivity is close to -1. Under this condition, the graphene multilayer exhibits asymmetry which appears as a very large difference between waves propagating upward and downward with respect to multilayer boundaries. One of them has a very high attenuation constant and neither of the waves undergo reflection at slab interfaces, resulting in total absorption even for an optically ultra-thin slab.

  17. Nonspecular scattering from extreme ultraviolet multilayer coatings

    Microsoft Academic Search

    D. G. Stearns; Eric M. Gullikson

    2000-01-01

    We review our recent studies of nonspecular scattering from multilayer coatings designed for high reflectivity in the wavelength range of 1–100nm. A linear, continuum growth model is used to describe the structure of the interfacial roughness in the multilayer coatings. This model accounts for both the partial replication of the substrate roughness and the intrinsic roughness introduced by the multilayer

  18. Center for Nanoscale Systems (CNS)

    NSDL National Science Digital Library

    The Center for Nanoscale Systems (CNS) is a part of Harvard University's Faculty of Arts and Sciences (FAS). Their scientific focus is on how nanoscale components can be integrated into large and complex interacting systems. Studying very small structures and how their behavior differs from macroscopic objects is only part of the story. We also must investigate how systems emerge, how they can be built, and how they behave. CNS is a member of the National Science Foundationâ??s National Nanotechnology Infrastructure Network (NNIN) initiative to create a national network of world-class facilities available to all researchers. Through our CNS/NNIN User Program, our facilities are available for use by researchers not just at Harvard, but by any academic or non-academic researchers in the country. We welcome and encourage researchers from Harvard and beyond to take a look at the many facilities that CNS has to offer to assist in your research goals. CNS has the tools and knowledgeable technical staff ready to assist in making your project a success. Nanotechnology is a new and constantly evolving area of study. As a result, there is a lot of new and constantly updated information contained in the pages of our website. Whether you are a CNS facility user, principal investigator, potential user, or interested in nanotechnology on any level, we invite you to take a tour of our website.

  19. A nanoscale shape memory oxide.

    PubMed

    Zhang, Jinxing; Ke, Xiaoxing; Gou, Gaoyang; Seidel, Jan; Xiang, Bin; Yu, Pu; Liang, Wen-I; Minor, Andrew M; Chu, Ying-Hao; Van Tendeloo, Gustaaf; Ren, Xiaobing; Ramesh, Ramamoorthy

    2013-01-01

    Stimulus-responsive shape-memory materials have attracted tremendous research interests recently, with much effort focused on improving their mechanical actuation. Driven by the needs of nanoelectromechanical devices, materials with large mechanical strain, particularly at nanoscale level, are therefore desired. Here we report on the discovery of a large shape-memory effect in bismuth ferrite at the nanoscale. A maximum strain of up to ~14% and a large volumetric work density of ~600±90?J?cm(-3) can be achieved in association with a martensitic-like phase transformation. With a single step, control of the phase transformation by thermal activation or electric field has been reversibly achieved without the assistance of external recovery stress. Although aspects such as hysteresis, microcracking and so on have to be taken into consideration for real devices, the large shape-memory effect in this oxide surpasses most alloys and, therefore, demonstrates itself as an extraordinary material for potential use in state-of-art nanosystems. PMID:24253399

  20. Nanoscale

    NSDL National Science Digital Library

    Nanotechnology continues to be a field of inquiry that is growing quickly, and this new online peer reviewed journal is a most welcome addition. The journal is published monthly as a collaborative venture between RSC Publishing and the National Center for Nanoscience and Technology (NCNST) in Beijing, China. Some of the topics covered in the journal include nanoelectronics, molecular nanoscience, and nanomedicine. The first issues was released in September 2009, and visitors can read through pieces like "How safe are carbon nanotubes?" and "Mechanised nanoparticles for drug delivery". On the journal's site, visitors can browse through the archive, sign up for their RSS feed, and also read over the author guidelines. Finally they can also use some of their online "Tools" to send along a link to the journal to a friend or colleague.

  1. An investigation of PVdF/PVC-based blend electrolytes with EC/PC as plasticizers in lithium battery applications

    NASA Astrophysics Data System (ADS)

    Rajendran, S.; Sivakumar, P.

    2008-03-01

    Solid polymer electrolytes (SPEs) composed of poly(vinylidene fluoride) (PVdF)-poly(vinyl chloride) (PVC) complexed with lithium perchlorate (LiClO 4) as salt and ethylene carbonate (EC)/propylene carbonate (PC) as plasticizers were prepared using solvent-casting technique, with different weight ratios of EC and PC. The amorphicity and complexation behavior of the polymer electrolytes were confirmed using X-ray diffraction (XRD) and FTIR studies. TG/DTA and scanning electron microscope (SEM) studies explained the thermal stability and surface morphology of electrolytes, respectively. The prepared thin films were subjected to AC impedance measurements as a function of temperature ranging from 302 to 373 K. The temperature-dependence conductivity of polymer films seems to obey VTF relation.

  2. Polyvinylidenefluoride (PVdF) based novel polymer electrolytes complexed with Mg(ClO{4}){2}

    NASA Astrophysics Data System (ADS)

    Vickraman, P.; Aravindan, V.; Srinivasan, T.; Jayachandran, M.

    2009-01-01

    The polyvinylidenefluoride (PVdF) based novel polymer electrolytes have been prepared by solution casting technique for solid state rechargeable magnesium batteries. Tetraglyme and tetrabutyl ammoniumchloride were used respectively as plasticizer and filler. The Mg(ClO{4})4 was used as conducting source. A.c. impedance spectroscopy results reveal that 5 wt% TBACl containing electrolyte show the maximum conductivity of 4.32 × 10-4 S/cm at ambient temperature. This electrolyte was electrochemically stable upto 1.5 V which was observed through linear sweep voltammetry. X-ray diffractograms studies suggest that the electrolytes are completely in amorphous phase. The improved entanglement like surface morphology was well observed for 5 wt% TBACl containing electrolyte by scanning electron microscope. The activation energy and coherence length were calculated.

  3. Structural features and gas tightness of EB-PVD 1Ce10ScSZ electrolyte films

    NASA Astrophysics Data System (ADS)

    Andrzejczuk, M.; Vasylyev, O.; Brychevskyi, M.; Dubykivskyi, L.; Smirnova, A.; Lewandowska, M.; Kurzyd?owski, K. J.; Steinberger-Wilckens, R.; Mertens, J.; Haanappel, V.

    2012-09-01

    The structure of Ceria doped Scandia Stabilized Zirconia (1Ce10ScSZ) electrolyte film deposited by EB-PVD (Electron Beam-Physical Vapour Deposition) technique on NiO-ZrO2 substrate was characterized by electron microscopy. The highly porous substrate was densely covered by deposited film without any spallation. The produced electrolyte layer was of a columnar structure with bushes, bundles of a diameter up to 30 ?m and diverse height. Between the columns, delamination cracks of few microns length were visible. The annealing of zirconia film at 1000 °C resulted in its densification. The columnar grains and delaminating cracks changed their shape into a bit rounded. High magnification studies revealed nanopores 5-60 nm formed along the boundaries of the columnar grains during annealing. High-quality contacts between the electrolyte film and anode substrate ensured good conductivity of the electrolyte film and high efficiency of SOFC.

  4. A multilayered neural network controller

    Microsoft Academic Search

    Demetri Psaltis; Athanasios Sideris; Alan A. Yamamura

    1988-01-01

    A multilayered neural network processor is used to control a given plant. Several learning architectures are proposed for training the neural controller to provide the appropriate inputs to the plant so that a desired response is obtained. A modified error-back propagation algorithm, based on propagation of the output error through the plant, is introduced. The properties of the proposed architectures

  5. Multilayer feedforward potential function network

    Microsoft Academic Search

    Lee Sukhan; Rhee M. Kil

    1988-01-01

    The authors present a multilayer feedforward network, called the Gaussian potential function network (GPFN), performing association or classification based on a set of potentially fields synthesized over the domain of input space by a number of Gaussian potential function units (GPFUs). A GPFU as a basic component of the GPFN is designed to generate a Gaussian form of a potential

  6. New directions for nanoscale thermoelectric materials research

    NASA Technical Reports Server (NTRS)

    Dresselhaus, M. S.; Chen, G.; Tang, M. Y.; Yang, R. G.; Lee, H.; Wang, D. Z.; Ren, F.; Fleurial, J. P.; Gogna, P.

    2005-01-01

    Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena with both bulk samples containing nanoscale constituents and nanoscale materials exhibiting enhanced thermoelectric performance in their own right. Prior theoretical and experimental proof of principle studies on isolated quantum well and quantum wire samples have now evolved into studies on bulk samples containing nanostructured constituents. In this review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications. A review of some of the results obtained to date are presented.

  7. CdS nanoscale photodetectors.

    PubMed

    Deng, Kaimo; Li, Liang

    2014-05-01

    CdS nanostructures have received much attention in recent years as building blocks for optoelectronic devices due to their unique physical and chemical properties. This progress report provides an overview of recent research about rational design of CdS nanoscale photodetectors. Three kinds of photodetectors according to the metal-semiconductor contact types are discussed in detail: Ohmic contact, Schottky contact, and field enhanced transistor configuration. The focus is on the tuning of optical and electrical properties CdS nanostructures by element doping, composition and bandgap engineering, and heterojunction integration, along with thus modified device performances generated during these tuning processes. Latest concepts of photodetector design such as flexible, self-powered, plasmonic, and piezophototronic photodetectors with novel properties are introduced to demonstrate the future directions of such an exciting research field. PMID:24634326

  8. Nanoscale materials for hyperthermal theranostics.

    PubMed

    Smith, Bennett E; Roder, Paden B; Zhou, Xuezhe; Pauzauskie, Peter J

    2015-04-01

    Recently, the use of nanoscale materials has attracted considerable attention with the aim of designing personalized therapeutic approaches that can enhance both spatial and temporal control over drug release, permeability, and uptake. Potential benefits to patients include the reduction of overall drug dosages, enabling the parallel delivery of different pharmaceuticals, and the possibility of enabling additional functionalities such as hyperthermia or deep-tissue imaging (LIF, PET, etc.) that complement and extend the efficacy of traditional chemotherapy and surgery. This mini-review is focused on an emerging class of nanometer-scale materials that can be used both to heat malignant tissue to reduce angiogenesis and DNA-repair while simultaneously offering complementary imaging capabilities based on radioemission, optical fluorescence, magnetic resonance, and photoacoustic methods. PMID:25816102

  9. Charge transport in nanoscale junctions.

    PubMed

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-01

    Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at the molecular level. Nanoscale charge transport experiments in ionic liquids extend the field to high temperatures and to systems with intriguing interfacial potential distributions. Other directions may include dye-sensitized solar cells, new sensor applications and diagnostic tools for the study of surface-bound single molecules. Another motivation for this special issue is thus to highlight activities across different research communities with nanoscale charge transport as a common denominator. This special issue gathers 27 articles by scientists from the United States, Germany, the UK, Denmark, Russia, France, Israel, Canada, Australia, Sweden, Switzerland, the Netherlands, Belgium and Singapore; it gives us a flavour of the current state-of-the-art of this diverse research area. While based on contributions from many renowned groups and institutions, it obviously cannot claim to represent all groups active in this very broad area. Moreover, a number of world-leading groups were unable to take part in this project within the allocated time limit. Nevertheless, we regard the current selection of papers to be representative enough for the reader to draw their own conclusions about the current status of the field. Each paper is original and has its own merit, as all papers in Journal of Physics: Condensed Matter special issues are subjected to the same scrutiny as regular contributions. The Guest Editors have deliberately not defined the specific subjects covered in this issue. These came out logically from the development of this area, for example: 'Traditional' solid state nanojunctions based on adsorbed layers, oxide films or nanowires sandwiched between two electrodes: effects of molecular structure (aromaticity, anchoring groups), symmetry, orientation, dynamics (noise patterns) and current-induced heating. Various 'physical effects': inelastic tunnelling and Coulomb blockade, polaron effects, switching modes, and negative differential resistance; the role of many particle excitations, new surface states in semiconductor electrodes, various mechanisms for

  10. Optical Spectroscopy at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Hong, Xiaoping

    Recent advances in material science and fabrication techniques enabled development of nanoscale applications and devices with superior performances and high degree of integration. Exotic physics also emerges at nanoscale where confinement of electrons and phonons leads to drastically different behavior from those in the bulk materials. It is therefore rewarding and interesting to investigate and understand material properties at the nanoscale. Optical spectroscopy, one of the most versatile techniques for studying material properties and light-matter interactions, can provide new insights into the nanomaterials. In this thesis, I explore advanced laser spectroscopic techniques to probe a variety of different nanoscale phenomena. A powerful tool in nanoscience and engineering is scanning tunneling microscopy (STM). Its capability in atomic resolution imaging and spectroscopy unveiled the mystical quantum world of atoms and molecules. However identification of molecular species under investigation is one of the limiting functionalities of the STM. To address this need, we take advantage of the molecular `fingerprints' - vibrational spectroscopy, by combining an infrared light sources with scanning tunneling microscopy. In order to map out sharp molecular resonances, an infrared continuous wave broadly tunable optical parametric oscillator was developed with mode-hop free fine tuning capabilities. We then combine this laser with STM by shooting the beam onto the STM substrate with sub-monolayer diamondoids deposition. Thermal expansion of the substrate is detected by the ultrasensitive tunneling current when infrared frequency is tuned across the molecular vibrational range. Molecular vibrational spectroscopy could be obtained by recording the thermal expansion as a function of the excitation wavelength. Another interesting field of the nanoscience is carbon nanotube, an ideal model of one dimensional physics and applications. Due to the small light absorption with nanometer size, individual carbon nanotube is not visible under any conventional microscopy and characterization of individual nanotube becomes a focused research interest. Although electron microscopies and optical spectroscopies are developed previously to study carbon nanotubes, none of them permitted versatile imaging and spectroscopy of individual nanotube in a non-invasive, high throughput and ambient way. In this thesis a new polarization-based optical microscopy and spectroscopy is developed with exceedingly better contrast for one dimensional nano-materials and capability of individual carbon nanotube imaging and spectroscopy. This development provides a reliable way to measure the absolute absorption cross-section of individual chirality-defined carbon nanotubes. It also enables fast profiling for growth optimization and in situ characterization for functioning carbon nanotube devices. Two dimensional systems constitute another important family of nanomaterials, ranging from semi-metal (graphene), semiconductors (transition metal dichalcogenides) to insulators (h-BN). Despite of their scientific significance, they present a complete set of 2D building blocks for two dimensional electronics and optoelectronics. Heterostructures purely made of 2D thin films hold great promises due to functionality, scalability and ultrathin nature. Understanding the properties of the coupled heterolayers will be important and intriguing for these applications. With the advanced ultrafast laser spectroscopy, we study the dynamics of charge transfer process in two dimensional atomically thin semiconductors heterostructures. An extremely efficient charge transfer process is identified in atomically thin MoS2/WS2 system, which is expected to form a type-II heterojunction. Our discovery would greatly facilitate further studies of 2D materials as a photovoltaic device.

  11. Simulations of Metallic Nanoscale Structures

    NASA Astrophysics Data System (ADS)

    Jacobsen, Karsten W.

    2003-03-01

    Density-functional-theory calculations can be used to understand and predict materials properties based on their nanoscale composition and structure. In combination with efficient search algorithms DFT can furthermore be applied in the nanoscale design of optimized materials. The first part of the talk will focus on two different types of nanostructures with an interesting interplay between chemical activity and conducting states. MoS2 nanoclusters are known for their catalyzing effect in the hydrodesulfurization process which removes sulfur-containing molecules from oil products. MoS2 is a layered material which is insulating. However, DFT calculations indicates the exsistence of metallic states at some of the edges of MoS2 nanoclusters, and the calculations show that the conducting states are not passivated by for example the presence of hydrogen gas. The edge states may play an important role for the chemical activity of MoS_2. Metallic nanocontacts can be formed during the breaking of a piece of metal, and atomically thin structures with conductance of only a single quantum unit may be formed. Such open metallic structures are chemically very active and susceptible to restructuring through interactions with molecular gases. DFT calculations show for example that atomically thin gold wires may incorporate oxygen atoms forming a new type of metallic nanowire. Adsorbates like hydrogen may also affect the conductance. In the last part of the talk I shall discuss the possibilities for designing alloys with optimal mechanical properties based on a combination of DFT calculations with genetic search algorithms. Simulaneous optimization of several parameters (stability, price, compressibility) is addressed through the determination of Pareto optimal alloy compositions within a large database of more than 64000 alloys.

  12. Multilayer Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    DeLay, Tom

    2005-01-01

    A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of each end fitting accommodates this layer. Depending on the application, this layer could be, for example, a layer of rubber, a polymer film, or an electrodeposited layer of metal. If the fluid to be contained in the tank is a gas, then the best permeation barrier is electrodeposited metal (typically copper or nickel), which can be effective at a thickness of as little as 0.005 in (.0.13 mm). The electrodeposited metal becomes molecularly bonded to the second step on each metallic end fitting. The permeation-barrier layer is covered with many layers of filament-wound composite material, which could be the same as, or different from, the composite material of the inner shell. Finally, the filament-wound composite material is cured in an ov

  13. Dynamics of sliding mechanisms in nanoscale friction

    E-print Network

    Yim, Shon W., 1973-

    2002-01-01

    Nanotribology is the study of friction and wear at the nanoscale, with relevance to such applications as micromechanical systems (MEMS) and thin, hard coatings. For these systems, classical laws of friction are inappropriate ...

  14. Nanoscale science: Complex rules for soft systems

    NASA Astrophysics Data System (ADS)

    Glotzer, Sharon C.

    2003-11-01

    The nanometre scale is a brave new world for scientists - mixing materials at such small dimensions can cause all sorts of surprising effects. New studies of experimental systems on the nanoscale further our understanding of these complex phenomena.

  15. Imaging and Nanoscale Characterization Art Baddorf*

    E-print Network

    Pennycook, Steve

    * Stephen Jesse David Joy(1) Sergei Kalinin* An-Ping Li Peter Maksymovych Minghu Pan Alexander Tselev(1 Sergei Kalinin* Electronic and Ionic Functionality on the Nanoscale Bobby Sumpter* Functional Polymer

  16. Nanoscale thermal radiation between two gold surfaces

    E-print Network

    Shen, Sheng

    In this letter, we measured the nanoscale thermal radiation between a microsphere and a substrate which were both coated with thick gold films. Although gold is highly reflective for thermal radiation, the radiative heat ...

  17. First Principles Modeling of Metal/Ceramic Multilayer Nano-heterostructures.

    SciTech Connect

    Yadav, Satyesh K. [Los Alamos National Laboratory; Wang, Jian [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory; Liu, Xiang-Yang [Los Alamos National Laboratory; Ramprasad, Ramamurthy [Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA

    2012-07-31

    Nanoscaled multilayer films composed of metals and ceramics have been explored for their potential applications as ductile, yet strong, materials. It is believed that at the nanoscale, the interfaces between the two materials constituting the multilayer assume an increasingly important role in determining the properties, as they comprise a more significant volume fraction of the multilayer with decreasing layer thickness. In this ab initio work, density functional theory was used to calculate the ideal shear strengths of pure Al, pure TiN, the Al/TiN interfacial region, and Al/TiN multilayers. The ideal shear strength of the Al/TiN interface was found to vary from very low (on the order of the ideal shear strength of Al) to very high (on the order of the ideal shear strength of TiN), depending on whether the TiN at the interface was Ti- or N-terminated, respectively. The results suggest that the shear properties of Al/TiN depend strongly on the chemistry of the interface, Al:N versus Al:Ti terminations. Nevertheless, for the Al/TiN multilayers, the ideal shear strength was limited by shear in the Al layer away from the interface, even when the individual layer thickness is less than a nanometer. Further we found an unusual structural rotation of bulk single-crystal Al under uniaxial compressive strains. It was found that under strains either along the <11-2> or the <111> directions, beyond a critical stress of about 13 GPa, the Al crystal can rotate through shear in the Shockley partial direction (i.e.,<11-2>) on the {l_brace}111{r_brace} plane, in an attempt to relieve internal stresses. This phenomenon reveals a possible mechanism leading to the onset of homogeneous dislocation nucleation in Al under high uniaxial compressions.

  18. Nanoscale Hydrophobic Interaction and Nanobubble Nucleation

    NASA Astrophysics Data System (ADS)

    Koishi, T.; Yoo, S.; Yasuoka, K.; Zeng, X. C.; Narumi, T.; Susukita, R.; Kawai, A.; Furusawa, H.; Suenaga, A.; Okimoto, N.; Futatsugi, N.; Ebisuzaki, T.

    2004-10-01

    We report large-scale atomistic simulation of midrange nanoscale hydrophobic interaction, manifested by the nucleation of nanobubble between nanometer-sized hydrophobes at constrained equilibrium. When the length scale of the hydrophobes is greater than 2nm, the nanobubble formation shows hysteresis behavior resembling the first-order transition. Calculation of the potential of mean force versus interhydrophobe distance provides a quantitative measure of the strength of the nanoscale hydrophobic interaction.

  19. Science and Technology at the Nanoscale

    NSDL National Science Digital Library

    Odom, Teri W.

    Northwestern University offers this graduate course on nanoscience to introduce students to the field. Taught by Professor Teri Odom, this course presents students with contemporary issues in nanoscience and nanotechnology as well as provide training on advanced nanoscale instrumentation. The website includes PDF lecture slideshows that provide more detailed information on subjects such as scanning probe microscopy, nanofabrication, and nanoscale electronics and photonics. This would be a good resource for teachers who want to incorporate nanoscience into their pre-existing chemistry classes.

  20. Anomalous magnetoresistance in Fibonacci multilayers

    NASA Astrophysics Data System (ADS)

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

    2012-06-01

    We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

  1. Multilayer weighted social network model

    NASA Astrophysics Data System (ADS)

    Murase, Yohsuke; Török, János; Jo, Hang-Hyun; Kaski, Kimmo; Kertész, János

    2014-11-01

    Recent empirical studies using large-scale data sets have validated the Granovetter hypothesis on the structure of the society in that there are strongly wired communities connected by weak ties. However, as interaction between individuals takes place in diverse contexts, these communities turn out to be overlapping. This implies that the society has a multilayered structure, where the layers represent the different contexts. To model this structure we begin with a single-layer weighted social network (WSN) model showing the Granovetterian structure. We find that when merging such WSN models, a sufficient amount of interlayer correlation is needed to maintain the relationship between topology and link weights, while these correlations destroy the enhancement in the community overlap due to multiple layers. To resolve this, we devise a geographic multilayer WSN model, where the indirect interlayer correlations due to the geographic constraints of individuals enhance the overlaps between the communities and, at the same time, the Granovetterian structure is preserved.

  2. Anomalous magnetoresistance in Fibonacci multilayers.

    SciTech Connect

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A. (Materials Science Division); (Universidade Federal do Rio Grande do Norte)

    2012-01-01

    We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

  3. Multilayer coatings on figured optics

    Microsoft Academic Search

    Stephen P. Vernon; Daniel G. Stearns; Robert S. Rosen; Natale M. Ceglio; David P. Gaines; Michael K. Krumrey; Peter Mueller

    1992-01-01

    Soft x-ray projection lithography (SXPL) requires uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f 3.4 and f 6 optics 5 and 7.5 cm in diameter using planar dc magnetron

  4. Casting Of Multilayer Ceramic Tapes

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

  5. Nanoscale Architectures for Energy Applications

    NASA Astrophysics Data System (ADS)

    Wong, Stanislaus

    2009-03-01

    In my group, we have developed a number of different potential architecture systems for gaining insights into energy storage and photovoltaics. In one manifestation of our efforts, generating a heterojunction comprising nanotubes and nanocrystals, externally bound and connected, has been significant. The unique, innovative, and important aspect of this particular nanoscale architecture is that it takes advantage of the tunability, in terms of size, shape, and chemistry, of nanotubes and nanocrystals, to create a sharp junction interface, whose properties are inherently manipulable, tailorable, and hence, predictable. For example, the electrical resistance of nanotube-nanoparticle networks is dependent on the nanoscale junctions that exist between these constituent nanomaterials as well as on microscale and macroscale connectivity. Thus, rational design of these nanomaterials is critical to a fundamental understanding of charge transport in single molecules and the determination of their conductance. Results on these systems can therefore be used to increase understanding of intrinsic factors affecting carrier mobility, such as electronic structure, carrier trapping, and delocalization. In a second manifestation, three-dimensional, dendritic micron- scale spheres of alkali metal hydrogen titanate 1D nanostructures (i.e.: nanowires and nanotubes) have been generated using a modified hydrothermal technique in the presence of hydrogen peroxide and an alkali metal hydroxide solution. Sea-urchin-like assemblies of these 1D nanostructures have been transformed into their hydrogen titanate analogues by neutralization as well as into their corresponding semiconducting, anatase titania nanostructured counterparts through a moderate high-temperature annealing dehydration process without destroying the 3D hierarchical structural motif. The as-prepared hollow spheres of titanate and titania 1D nanostructures have overall diameters, ranging from 0.8 ?m to 1.2 ?m, while the interior of these aggregates are vacuous with a diameter range of 100 to 200 nm. We have demonstrated that these assemblies are useful for example as active photocatalysts for the degradation of synthetic Procion Red dye under UV light illumination. In a third set of experiments, a size- and shape-dependent morphological transformation was demonstrated during the hydrothermal soft chemical transformation, in neutral solution, of titanate nanostructures into their anatase titania counterparts. Our results indicate that as-synthesized titania nanostructures possessed higher photocatalytic activity than the commercial titania precursors from whence they were derived.

  6. Structural transitions in nanoscale systems

    NASA Astrophysics Data System (ADS)

    Yoon, Mina

    In this work I investigate three different materials: nanoscale carbon systems, ferrofluid systems, and molecular-electronic devices. In particular, my study is focused on the theoretical understanding of structural changes and the associated electronic, mechanical, and magnetic properties of these materials. To study the equilibrium packing of fullerenes in carbon nanotube peapods optimization techniques were applied. In agreement with experimental measurements, my results for nanotubes containing fullerenes with 60--84 atoms indicate that the axial separation between the fullerenes is smaller than in the bulk crystal. The reduction of the inter-fullerene distance and also the structural relaxation of fullerenes result from a large internal pressure within the peapods. This naturally induced "static" pressure may qualify nanotubes as nanoscale autoclaves for chemical reactions. Combining total energy calculations with a search of phase space, I investigated the microscopic fusion mechanism of C60 fullerenes. I show that the (2+2) cycloaddition reaction, a necessary precursor for fullerene fusion, can be accelerated inside a nanotube. Fusion occurs along the minimum energy path as a finite sequence of Stone-Wales (SW) transformations. A detailed analysis of the transition states shows that Stone-Wales transformations are multi-step processes. I propose a new microscopic mechanism to explain the unusually fast fusion process of carbon nanotubes. The detailed pathway for two adjacent (5, 5) nanotubes to gradually merge into a (10, 10) tube, and the transition states have been identified. The propagation of the fused region is energetically favorable and proceeds in a morphology reminiscent of a Y-junction via a so called zipper mechanism, involving only SW bond rearrangements with low activation barriers. Using density functional theory, the equilibrium structure, stability, and electronic properties of nanostructured, hydrogen terminated diamond fragments have been studied. Such diamondoids can enter spontaneously into carbon nanotubes where polymerization of diamondoids is favourable. I studied the equilibrium structure of large but finite aggregates of magnetic dipoles, modeling a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. These structural changes depend on external parameters and result from a competition between various energy terms, which can be described analytically within a continuum approximation. (Abstract shortened by UMI.)

  7. Ultra-thin multilayer capacitors.

    SciTech Connect

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  8. Multi-layer seal for electrochemical devices

    DOEpatents

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-16

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  9. Multi-layer seal for electrochemical devices

    DOEpatents

    Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

    2010-09-14

    Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

  10. New Training Algorithms for Dependently Initialized Multilayer Perceptrons

    E-print Network

    Manry, Michael

    New Training Algorithms for Dependently Initialized Multilayer Perceptrons Walter H. Delashmit of multilayer perceptron training, training error usually fails to be a monotonically nonincreasing function weights. I. INTRODUCTION When multilayer perceptrons (MLPs) with different numbers of hidden units

  11. Local Electrostatics within a Polyelectrolyte Multilayer with Embedded Weak Polyelectrolyte

    E-print Network

    Granick, Steve

    Local Electrostatics within a Polyelectrolyte Multilayer with Embedded Weak Polyelectrolyte Anne investigate local electrostatics within a polyelectrolyte multilayer formed from layer- by-layer self infrared measurements of these multilayer films using FTIR-ATR, Fourier transform infrared spectroscopy

  12. Fabrication of Microporous Thin Films from Polyelectrolyte Multilayers

    E-print Network

    Barrett, Christopher

    Fabrication of Microporous Thin Films from Polyelectrolyte Multilayers J. D. Mendelsohn, C. J, highly uniform microporous thin films. Multilayers of weak polyelectrolytes were assembled onto silicon and biomaterial applications. Introduction The fabrication of polyelectrolyte multilayer thin films has received

  13. Investigations on friction and wear mechanisms of the PVD-TiAlN coated carbide in dry sliding against steels and cast iron

    Microsoft Academic Search

    W. Grzesik; Z. Zalisz; S. Krol; P. Nieslony

    2006-01-01

    The tribological behaviour of the monolayer PVD-titanium aluminium nitride (TiAlN) coated carbide inserts in unidirectional dry sliding against steel and cast iron counterparts was investigated using the pin-on-disc standard test with varying sliding speeds and normal loads. Three different materials of various machinability rates were used as the counterparts, namely the normalised medium carbon steel C45 equivalent to AISI 1045,

  14. Tailored microstructure of EB-PVD 8YSZ thermal barrier coatings with low thermal conductivity and high thermal reflectivity for turbine applications

    Microsoft Academic Search

    Douglas E. Wolfe; Jogender Singh; Robert A. Miller; Jeff I. Eldridge; Dong-Ming Zhu

    2005-01-01

    This paper discusses microstructural changes produced by two novel approaches using electron beam-physical vapor deposition (EB-PVD) in which periodic strain fields\\/microporosity was incorporated within the large columnar grains of ZrO2–8 wt.% Y2O3 (8YSZ). The traditional columnar microstructure of partially stabilized zirconia has been slightly modified to produce a lower thermal conductive thermal barrier coating (TBC) by periodically interrupting the condensing

  15. Characterization of a hybrid PVD\\/PACVD system for the deposition of TiC\\/CaO nanocomposite films by OES and probe measurements

    Microsoft Academic Search

    W. Kulisch; P. Colpo; F. Rossi; D. V. Shtansky; E. A. Levashov

    2004-01-01

    A hybrid PVD\\/PACVD system, which was used for the deposition of TiC\\/CaO nanocomposite films from a TiC0.5+10% CaO target, has been characterized by optical emission spectroscopy (OES), electrical probe measurements and deposition experiments. The system consists of a dc magnetron unit to create a flux of species to be deposited, an inductively coupled rf Ar plasma by which these species

  16. Charge–discharge studies on a lithium cell composed of PVdF-HFP polymer membranes prepared by phase inversion technique with a nanocomposite cathode

    Microsoft Academic Search

    A Manuel Stephan; Dale Teeters

    2003-01-01

    A novel polymer membrane of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by the phase inversion technique with two different non-solvents, 1-butanol or hexane. The prepared films were analyzed by scanning electron microscope (SEM) and nitrogen absorption\\/desorption techniques. The change in the morphology and pore diameter of the films prepared with different non-solvents correlates with the structure of the non-solvents used.

  17. Tailored microstructure of zirconia and hafnia-based thermal barrier coatings with low thermal conductivity and high hemispherical reflectance by EB-PVD

    Microsoft Academic Search

    J. Singh; D. E. Wolfe; R. A. Miller; J. I. Eldridge; Dong-Ming Zhu

    2004-01-01

    Zirconia and hafnia based thermal barrier coating materials were produced by industrial prototype electron beam-physical vapor deposition (EB-PVD). Columnar microstructure of the thermal barrier coatings were modified with controlled microporosity and diffuse sub-interfaces resulting in lower thermal conductivity (20–30% depending up on microporosity volume fraction), higher thermal reflectance (15–20%) and more strain tolerance as compared with standard thermal barrier coatings

  18. Employment of the finite element method for determining stresses in coatings obtained on high-speed steel with the PVD process

    Microsoft Academic Search

    L. A. Dobrza?ski; A. ?liwa; W. Kwa?ny

    2005-01-01

    The paper presents the possibility to employ the finite element method for evaluation of stresses in the Ti+TiN coating obtained in the magnetron PVD process on the sintered high-speed steel of the ASP 30 type, taking into account their deposition conditions. FEM was used to evaluate stress error in the simulated model. Computer simulation results were compared with the experimental

  19. New types of multi-component hard coatings deposited by ARC PVD on steel pre-treated by pulsed plasma beams

    Microsoft Academic Search

    Z. Werner; J. Stanis?awski; J. Piekoszewski; E. A. Levashov; W Szymczyk

    2003-01-01

    The paper presents the results of experiments on depositing of the multicomponent Ti–B–N, Ti–Si–N, and Ti–B–Si–N coatings on HSS steel using the ARC PVD technique in a novel two-step approach with the plasma pulse pretreatment. The coatings were characterized by X-ray diffraction and tribological tests (nanohardness measurements, scratch tests, wear resistance). The Ti–B–N coatings showed the highest values of hardness,

  20. Molecular Photovoltaics in Nanoscale Dimension

    PubMed Central

    Burtman, Vladimir; Zelichonok, Alexander; Pakoulev, Andrei V.

    2011-01-01

    This review focuses on the intrinsic charge transport in organic photovoltaic (PVC) devices and field-effect transistors (SAM-OFETs) fabricated by vapor phase molecular self-assembly (VP-SAM) method. The dynamics of charge transport are determined and used to clarify a transport mechanism. The 1,4,5,8-naphthalene-tetracarboxylic diphenylimide (NTCDI) SAM devices provide a useful tool to study the fundamentals of polaronic transport at organic surfaces and to discuss the performance of organic photovoltaic devices in nanoscale. Time-resolved photovoltaic studies allow us to separate the charge annihilation kinetics in the conductive NTCDI channel from the overall charge kinetic in a SAM-OFET device. It has been demonstrated that tuning of the type of conductivity in NTCDI SAM-OFET devices is possible by changing Si substrate doping. Our study of the polaron charge transfer in organic materials proposes that a cation-radical exchange (redox) mechanism is the major transport mechanism in the studied SAM-PVC devices. The role and contribution of the transport through delocalized states of redox active surface molecular aggregates of NTCDI are exposed and investigated. This example of technological development is used to highlight the significance of future technological development of nanotechnologies and to appreciate a structure-property paradigm in organic nanostructures. PMID:21339983

  1. Magnetic Alloys in Nanoscale Biomaterials

    SciTech Connect

    Leventouri, T. H. [Florida Atlantic University; Melechko, Anatoli Vasilievich [ORNL; Sorge, Korey D. [Florida Atlantic University; Klein, Kate L [ORNL; Fowlkes, Jason Davidson [ORNL; Rack, P. D. [University of Tennessee, Knoxville (UTK); Anderson, Ian M [ORNL; Thompson, James R [ORNL; McKnight, Timothy E [ORNL; Simpson, Michael L [ORNL

    2006-01-01

    Fe-Co composition gradient and Fe-Pt multilayer alloy films were tested as catalysts for growing vertically aligned carbon nanofibers (VACNFs) by plasma-enhanced chemical vapor deposition (PECVD). The Fe-Co film yielded nanofibers with alloy tips in a wide compositional range varying from 8.15 pct Fe at the Co-rich end to 46.29 pct Fe in the middle of the wafer as determined by energy-dispersive X-ray analysis. Two Fe-Co cubic phases (SG Pm3m, Pm{bar 3}m) were identified by preliminary X-ray diffraction (XRD) measurements. Magnetic measurements showed a substantially greater hysteresis loop area and coercivity in Fe-Co catalyst nanoparticles as compared to the as deposited Fe-Co film. The Fe-Pt film did not break into FePt alloy nanoparticles under the applied processing parameters and thus the utility of FePt as a VACNF catalyst has been inconclusive.

  2. Polarization-dependent MAD holography: Nanoscale Magnetic Imaging of Nonperiodic Objects

    NASA Astrophysics Data System (ADS)

    Wang, Tianhan; Zhu, Diling; Wu, Benny; Hellwig, Olav; Stohr, Joachim; Scherz, Andreas

    2010-03-01

    We present a novel approach to the nanoscale imaging of nonperiodic magnetic structures by introducing x-ray polarization dependence to the multiple wavelength anomalous diffraction (MAD) phasing technique. Essential phase information can be extracted from the differences between coherent scattering patterns recorded at different x-ray wavelengths (on- or off-resonance) and polarizations. Combined with an iterative phase retrieval algorithm, the magnetization distribution can be reconstructed. Using left and right circularly polarized x-rays near the Co L3 edge, we successfully imaged the perpendicular magnetic worm domains of a Co/Pd multilayer sample within a 3 micron circular aperture. The absence of reference apertures and a resolution that is, in principle, only limited by the wavelength render this method attractive for polarization-dependent and element-specific studies in magnetism, correlated materials and polymer research. This research is supported by the U.S. Department of Energy, Office of Basic Energy Science.

  3. Nanoporous silicon multilayers for terahertz filtering

    E-print Network

    Murphy, Thomas E.

    to fabricate THz multilayer filters, including stacking and assem- bly of semiconductor wafers [1­5], ceramics,12]. Thick film sputter-deposition methods have also been used to fabricate multilayers of silicon, oxides; posted August 25, 2009 (Doc. ID 113473); published September 18, 2009 We describe the fabrication

  4. NONLINEAR CHANNEL EQUALIZATION USING MULTILAYER PERCEPTRONS WITH

    E-print Network

    Wong, Tan F.

    NONLINEAR CHANNEL EQUALIZATION USING MULTILAYER PERCEPTRONS WITH INFORMATION-THEORETIC CRITERION perceptron scheme trained with this information theoretic criterion to the problem of nonlinear channel are compared in terms of both performance and complexity. The idea of using multilayer perceptrons (MLP) has

  5. Coherent multilayer crystals and method of making

    DOEpatents

    Schuller, I.K.; Falco, C.M.

    1980-10-30

    A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  6. A benchtop method for the fabrication and patterning of nanoscale structures on polymers.

    PubMed

    Helt, James M; Drain, Charles M; Batteas, James D

    2004-01-21

    A benchtop method for the facile production of nanoscale metal structures on polymers is demonstrated. This approach allows for the design and patterning of a wide range of metallic structures on inexpensive polymer surfaces, affording the fabrication of nanoscaled platforms for use in the design of sensors, actuators, and disposable electronic and photonic devices. Numerous structures, from simple nanowires to multilayered metallic gratings, are demonstrated, with sizes ranging from microns to the nanoscale. The process involves molding a malleable metal film deposited on a rigid substrate such as mica, by the compression of a plastic polymer stamp with the desired pattern against the metal film. While under compression, an etchant is then used to modify the metal. Upon separation of the stamp from the support, micro- to nanoscaled metallic structures are found on the stamp and/or on the substrate. The sizes of the structures formed depend on the sizes of the features on the stamp but can be fine-tuned by about 4-fold through variations in both pressure and duration of etching. Also, depending on the processing, multiple dimension metallic structures can be obtained simultaneously in a single stamping procedure. The metallic structures formed on the stamp can also be subsequently transferred to another surface allowing for the construction of multilayered materials such as band gap gratings or the application of electrical contacts. Using this approach, fabrication of both simple and complex micro- to nanoscaled structures can be accomplished by most any researcher as even the grating structure of commercial compact disks may be used as stamps, eliminating the requirement of expensive lithographic processes to form simple structures. PMID:14719962

  7. Dynamic materials from microgel multilayers.

    PubMed

    Spears, Mark William; Herman, Emily S; Gaulding, Jeffrey C; Lyon, L Andrew

    2014-06-10

    Multilayer coatings made from hydrogel microparticles (microgels) are conceptually very simple materials: thin films composed of microgel building blocks held together by polyelectrolyte "glue". However, the apparent simplicity of their fabrication and structure belies extremely complex properties, including those of "dynamic" coatings that display rapid self-healing behavior in the presence of solvent. This contribution covers our work with these materials and highlights some of the key findings regarding damage mechanisms, healing processes, film structure/composition, and how the variation of fabrication parameters can impact self-healing behavior. PMID:24295444

  8. Bench-scale synthesis of nanoscale materials

    SciTech Connect

    Buehler, M.F.; Darab, J.G.; Matson, D.W.; Linehan, J.C.

    1993-12-01

    A novel flow-through hydrothermal method used to synthesize nanoscale powders is introduced by Pacific Northwest Laboratory. The process, Rapid Thermal Decomposition of precursors in Solution (RTDS), combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was demonstrated on a laboratory scale and scaled up to accommodate production rates attractive to industry. The process is able to produce a wide variety of metal oxides and oxyhydroxides. The powders are characterized by scanning and transmission electron microscopic methods, surface-area measurements, and x-ray diffraction. Typical crystallite sizes are less than 20 nanometers, with BET surface areas ranging from 100 to 400 m{sup 2}/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO{sub 2} produced by RTDS are included.

  9. Figure correction of multilayer coated optics

    DOEpatents

    Chapman; Henry N. (Livermore, CA), Taylor; John S. (Livermore, CA)

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  10. Atomistic Design and Simulations of Nanoscale Machines and Assembly

    NASA Technical Reports Server (NTRS)

    Goddard, William A., III; Cagin, Tahir; Walch, Stephen P.

    2000-01-01

    Over the three years of this project, we made significant progress on critical theoretical and computational issues in nanoscale science and technology, particularly in:(1) Fullerenes and nanotubes, (2) Characterization of surfaces of diamond and silicon for NEMS applications, (3) Nanoscale machine and assemblies, (4) Organic nanostructures and dendrimers, (5) Nanoscale confinement and nanotribology, (6) Dynamic response of nanoscale structures nanowires (metals, tubes, fullerenes), (7) Thermal transport in nanostructures.

  11. Nanoscale Transistors: Advanced VLSI Devices (Introductory Lecture)

    NSDL National Science Digital Library

    Lundstrom, Mark

    Contributed by Mark Lundstrom of Purdue University, this introductory lecture to nanoscale transistors is available both as a Flash video with audio and as presentation slides in PDF form (the links to these are on the right hand side of the page). The lecture introduces the course, which "examines the device physics of advanced transistors and the process, device, circuit, and systems considerations that enter into the development of new integrated circuit technologies." This is a helpful resource for nanotechnology instructors looking to introduce the concept of nanoscale transistors into their classrooms. For more from this course (lectures, assignments, etc.) click the Course Information Website link.

  12. Nanoscale Volcanoes: Accretion of Matter at Ion Sculpted Nanopores

    E-print Network

    Golovchenko, Jene A.

    Nanoscale Volcanoes: Accretion of Matter at Ion Sculpted Nanopores Toshiyuki Mitsui, Derek Stein 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

  13. Thermionic Energy Conversion with Nanoscale Materials and Devices

    Microsoft Academic Search

    Yang Liu; Timothy S. Fisher

    2006-01-01

    Prior studies on electron emission show possibly beneficial effects of nanoscale phenomena on energy-conversion characteristics. For example, recent work has shown that the electric field around a nanoscale field emission device can increase the average energy of emitted electrons. This geometric effect could be useful in cooling devices based on the Nottingham effect. We consider here the hypothesis that nanoscale

  14. Impact on multilayered composite plates

    NASA Technical Reports Server (NTRS)

    Kim, B. S.; Moon, F. C.

    1977-01-01

    Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

  15. Polyelectrolyte Multilayers in Tissue Engineering

    PubMed Central

    Detzel, Christopher J.; Larkin, Adam L.

    2011-01-01

    The layer-by-layer assembly of sequentially adsorbed, alternating polyelectrolytes has become increasingly important over the past two decades. The ease and versatility in assembling polyelectrolyte multilayers (PEMs) has resulted in numerous wide ranging applications of these materials. More recently, PEMs are being used in biological applications ranging from biomaterials, tissue engineering, regenerative medicine, and drug delivery. The ability to manipulate the chemical, physical, surface, and topographical properties of these multilayer architectures by simply changing the pH, ionic strength, thickness, and postassembly modifications render them highly suitable to probe the effects of external stimuli on cellular responsiveness. In the field of regenerative medicine, the ability to sequester growth factors and to tether peptides to PEMs has been exploited to direct the lineage of progenitor cells and to subsequently maintain a desired phenotype. Additional novel applications include the use of PEMs in the assembly of three-dimensional layered architectures and as coatings for individual cells to deliver tunable payloads of drugs or bioactive molecules. This review focuses on literature related to the modulation of chemical and physical properties of PEMs for tissue engineering applications and recent research efforts in maintaining and directing cellular phenotype in stem cell differentiation. PMID:21210759

  16. Interactions between glide dislocations and parallel interfacial dislocations in nanoscale strained layers

    SciTech Connect

    Akasheh, F.; Zbib, H. M.; Hirth, J. P.; Hoagland, R. G.; Misra, A. [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 (United States); MST Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2007-08-01

    Plastic deformation in nanoscale multilayered structures is thought to proceed by the successive propagation of single dislocation loops at the interfaces. Based on this view, we simulate the effect of predeposited interfacial dislocation on the stress (channeling stress) needed to propagate a new loop parallel to existing loops. Single interfacial dislocations as well as finite parallel arrays are considered in the computation. When the gliding dislocation and the predeposited interfacial array have collinear Burgers vectors, the channeling stress increases monotonically as the density of dislocations in the array increases. In the case when their Burgers vectors are inclined at 60 deg. , a regime of perfect plasticity is observed which can be traced back to an instability in the flow stress arising from the interaction between the glide dislocation and a single interfacial dislocation dipole. This interaction leads to a tendency for dislocations of alternating Burgers vectors to propagate during deformation leading to nonuniform arrays. Inclusion of these parallel interactions in the analysis improves the strength predictions as compared with the measured strength of a Cu-Ni multilayered system in the regime where isolated glide dislocation motion controls flow, but does not help to explain the observed strength saturation when the individual layer thickness is in the few nanometer range.

  17. Nanoscale Spectroscopy and Nanotechnology 8 Scientific Program

    E-print Network

    Kemner, Ken

    1 Nanoscale Spectroscopy and Nanotechnology 8 Scientific Program Gleacher Center Chicago, USA #12 & Nanometer Structure Consortium, and ,QuNano AB, Glo AB & Sol Voltaics AB, Ideon Science Park, Lund, Sweden. Hamburg, Germany). 9:15-9:30 Break 9:30-10:06 Session Chair: Y. Kim (RIKEN) (Invited) Nanowires

  18. Contacts Integration into functional nanoscale devices

    E-print Network

    Metlushko, Vitali

    Contacts Integration into functional nanoscale devices Joshua Sautner Nanotechnology Core Facility films comprising the GMR stack, contacts on the bottom of the device are mandatory. The problems associated with conventional techniques to handle bottom-side contacts, such as chemical-mechanical polishing

  19. Fats, Oils, and Colors of Nanoscale Materials

    NSDL National Science Digital Library

    Dana Horoszewski

    2006-12-01

    Phase changes and intermolecular forces are important physical science concepts but are not always easy to present in an active learning format. This article presents several interactive activities in which students plot the melting points of some fatty acids and explore the effect that the nanoscale size and shape of molecules have on the material's macroscopic phase properties.

  20. Nanoscale Calorimetry of Isolated Polyethylene Single Crystals

    E-print Network

    Allen, Leslie H.

    Nanoscale Calorimetry of Isolated Polyethylene Single Crystals A. T. KWAN, M. YU. EFREMOV, E. A-film differential scanning calorimetry to investigate the melt- ing of isolated polyethylene single crystals of lamellar single crystals of polyethylene (PE). We obtain thickness, diffraction, and calorimetry data

  1. On thermal radiation across nanoscale gaps

    NASA Astrophysics Data System (ADS)

    Budaev, Bair V.; Bogy, David B.

    2015-02-01

    It is shown that the analysis of radiative heat transport across a nanoscale gap cannot ignore the correlation between radiations from the different sides of the gap. This correlation can be neglected in two cases: when the gap is considerably wider than the dominant wavelength of radiation and when the temperatures on different sides of the gap are equal.

  2. Dynamic structural disorder in supported nanoscale catalysts

    SciTech Connect

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

  3. Dynamic structural disorder in supported nanoscale catalysts

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  4. Benchtop Nanoscale Patterning Using Soft Lithography

    ERIC Educational Resources Information Center

    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…

  5. LAMELLAR MAGNETISM ASSOCIATED WITH NANOSCALE EXSOLUTION

    E-print Network

    Dunin-Borkowski, Rafal E.

    LAMELLAR MAGNETISM ASSOCIATED WITH NANOSCALE EXSOLUTION IN THE ILMENITE-HEMATITE SOLID SOLUTION-hematite (FeTiO3-Fe2O3) solid solution is one of the most important magnetic phases in nature. Unusual magnetic, magnetic ordering, and exsolution. This presentation describes how this interaction leads to the phenomenon

  6. Fats, Oils, & Colors of a Nanoscale Material

    ERIC Educational Resources Information Center

    Lisensky, George C.; Horoszewski, Dana; Gentry, Kenneth L.; Zenner, Greta M.; Crone, Wendy C .

    2006-01-01

    Phase changes and intermolecular forces are important physical science concepts but are not always easy to present in an active learning format. This article presents several interactive activities in which students plot the melting points of some fatty acids and explore the effect that the nanoscale size and shape of molecules have on the…

  7. Nanoscale Characterization with Laser Picosecond Acoustics

    Microsoft Academic Search

    Oliver B. Wright

    2007-01-01

    Nanophotonics-the manipulation of light with nanomaterials-is a booming subject, its success owing to the host of nanoscale fabrication techniques now at our disposal. However, for the characterization of such nanomaterials it is expedient to turn to other types of waves with a wavelength commensurate with the nanostructure in question. One such choice is acoustic waves of nanometre wavelength. The aim

  8. Nanoscale Characterization with Laser Picosecond Acoustics

    Microsoft Academic Search

    Oliver B. Wright

    2007-01-01

    Nanophotonics—the manipulation of light with nanomaterials—is a booming subject, its success owing to the host of nanoscale fabrication techniques now at our disposal. However, for the characterization of such nanomaterials it is expedient to turn to other types of waves with a wavelength commensurate with the nanostructure in question. One such choice is acoustic waves of nanometre wavelength. The aim

  9. Multilayer composites and manufacture of same

    DOEpatents

    Holesinger, Terry G.; Jia, Quanxi

    2006-02-07

    The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

  10. Preface: Friction at the nanoscale

    NASA Astrophysics Data System (ADS)

    Fusc, Claudio; Smith, Roger; Urbakh, Michael; Vanossi, Andrea

    2008-09-01

    Interfacial friction is one of the oldest problems in physics and chemistry, and certainly one of the most important from a practical point of view. Everyday operations on a broad range of scales, from nanometer and up, depend upon the smooth and satisfactory functioning of countless tribological systems. Friction imposes serious constraints and limitations on the performance and lifetime of micro-machines and, undoubtedly, will impose even more severe constraints on the emerging technology of nano-machines. Standard lubrication techniques used for large objects are expected to be less effective in the nano-world. Novel methods for control and manipulation are therefore needed. What has been missing is a molecular level understanding of processes occurring between and close to interacting surfaces to help understand, and later manipulate friction. Friction is intimately related to both adhesion and wear, and all three require an understanding of highly non-equilibrium processes occurring at the molecular level to determine what happens at the macroscopic level. Due to its practical importance and the relevance to basic scientific questions there has been major increase in activity in the study of interfacial friction on the microscopic level during the last decade. Intriguing structural and dynamical features have been observed experimentally. These observations have motivated theoretical efforts, both numerical and analytical. This special issue focusses primarily on discussion of microscopic mechanisms of friction and adhesion at the nanoscale level. The contributions cover many important aspects of frictional behaviour, including the origin of stick-slip motion, the dependence of measured forces on the material properties, effects of thermal fluctuations, surface roughness and instabilities in boundary lubricants on both static and kinetic friction. An important problem that has been raised in this issue, and which has still to be resolved, concerns the possibility of controlling frictional response. The ability to control and manipulate frictional forces is extremely important for a variety of applications. These include magnetic storage and recording systems, miniature motors, and more. This special issue aims to provide an overview of current theoretical and experimental works on nanotribology and possible applications. In selecting the papers we have tried to maintain a balance between new results and review-like aspects, so that the present issue is self-contained and, we hope, readily accessible to non-specialists in the field. We believe that the particular appeal of this collection of papers also lies in the fusion of both experiment and theory, thus providing the connection to reality of the sometimes demanding, mathematically inclined contributions. Profound thanks go to all our colleagues and friends who have contributed to this special issue. Each has made an effort not only to present recent results in a clear and lucid way, but also to provide an introductory review that helps the reader to understand the different topics.

  11. Ion transport through polyelectrolyte multilayers.

    PubMed

    Carregal-Romero, Susana; Rinklin, Philipp; Schulze, Susanne; Schäfer, Martin; Ott, Andrea; Hühn, Dominik; Yu, Xiang; Wolfrum, Bernhard; Weitzel, Karl-Michael; Parak, Wolfgang J

    2013-12-01

    Polyelectrolyte multilayer (PEM) films and capsules loaded with ion-sensitive fluorophores can be used as ion-sensors for many applications including measurements of intracellular ion concentration. Previous studies have shown the influence of the PEM films/shells on the specific response of encapsulated ion-sensitive fluorophores. PEM shells are considered as semipermeable barriers between the environment and the encapsulated fluorophores. Parameters such as the time response of the encapsulated sensor can be affected by the porosity and charge of the PEM shell. In this study, the time response of an encapsulated pH-sensitive fluorophore towards pH changes in the surrounding environment is investigated. Furthermore, the conductance of PEM films for potassium ions is determined. PMID:24327382

  12. Flexible free-standing TiO2/graphene/PVdF films as anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ren, H. M.; Ding, Y. H.; Chang, F. H.; He, X.; Feng, J. Q.; Wang, C. F.; Jiang, Y.; Zhang, P.

    2012-12-01

    Graphene composites were prepared by hydrothermal method using titanium dioxide (TiO2) adsorbed graphene oxide (GO) sheets as precursors. Free-standing hybrid films for lithium-ion batteries were prepared by adding TiO2/graphene composites to the polyvinylidene fluoride (PVdF)/N-methyl-2-pyrrolidone (NMP) solution, followed by a solvent evaporation technique. These films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and various electrochemical techniques. Flexible films show an excellent cycling performance, which was attributed to the interconnected graphene conducting network, which depressed the increasing of electric resistance during the cycling.

  13. Layer-by-layer assembly of a streptavidin-fibronectin multilayer on biotinylated TiO(X).

    PubMed

    Lehnert, Michael; Rosin, Christopher; Knoll, Wolfgang; Veith, Michael

    2013-02-12

    The biomodification of surfaces, especially titanium, is an important issue in current biomedical research. Regarding titanium, it is also important to ensure a specific protein modification of its surface because here protein binding that is too random can be observed. Specific nanoscale architectures can be applied to overcome this problem. As recently shown, streptavidin can be used as a coupling agent to immobilize biotinylated fibronectin (bFn) on a TiO(X) surface. Because of the conformation of adsorbed biotinylated fibronectin on a streptavidin monolayer, it is possible to adsorb more streptavidin and biotinylated fibronectin layers. On this basis, an alternating protein multilayer can be built up. In contrast to common layer-by-layer technology, in this procedure the mechanism of layer adsorption is very specific because of the interaction of biotin and streptavidin. In addition, we showed that the assembly of this multilayer system and its stability are dependent on the degree of labeling of biotinylated fibronectin. Hence we conclude that it is possible to build up well-defined nanoscale protein architectures by varying the degree of labeling of biotinylated fibronectin. PMID:23311964

  14. Schwinger pair creation in multilayer graphene

    E-print Network

    M. A. Zubkov

    2012-04-05

    The low energy effective field model for the multilayer graphene (at ABC stacking) in external Electric field is considered. The Schwinger pair creation rate and the vacuum persistence probability are calculated using the semi - classical approach.

  15. Simplified methods of modeling multilayer reservoirs

    E-print Network

    Ryou, Sangsoo

    1993-01-01

    and Camacho suggested for hydraulically fracture wells. We also examined modeling responses of wells with positive skin factors completed in multilayer reservoirs with equivalent single layer solutions. More specifically, this work examined the boundary...

  16. Biological applications of weal polyelectrolyte multilayers

    E-print Network

    Berg, Michael C., Ph. D. Massachusetts Institute of Technology

    2005-01-01

    This thesis research focused on biological applications of ultra-thin weak polyelectrolyte multilayers with specific emphasis on cell patterning, drug delivery, and antibacterial coatings. All of these very different ...

  17. Subwavelength Multilayer Dielectrics: Ultrasensitive Transmission and Breakdown of Effective-Medium Theory

    NASA Astrophysics Data System (ADS)

    Herzig Sheinfux, Hanan; Kaminer, Ido; Plotnik, Yonatan; Bartal, Guy; Segev, Mordechai

    2014-12-01

    We show that a purely dielectric structure made of alternating layers of deep subwavelength thicknesses exhibits novel transmission effects which completely contradict conventional effective medium theories exactly in the regime in which those theories are commonly used. We study waves incident at the vicinity of the effective medium's critical angle for total internal reflection and show that the transmission through the multilayer structure depends strongly on nanoscale variations even at layer thicknesses smaller than ? /50 . In such deep subwavelength structures, we demonstrate dramatic changes in the transmission for variations in properties such as periodicity, order of the layers, and their parity. In addition to its conceptual importance, such sensitivity has important potential applications in sensing and switching.

  18. Subwavelength multilayer dielectrics: ultrasensitive transmission and breakdown of effective-medium theory.

    PubMed

    Herzig Sheinfux, Hanan; Kaminer, Ido; Plotnik, Yonatan; Bartal, Guy; Segev, Mordechai

    2014-12-12

    We show that a purely dielectric structure made of alternating layers of deep subwavelength thicknesses exhibits novel transmission effects which completely contradict conventional effective medium theories exactly in the regime in which those theories are commonly used. We study waves incident at the vicinity of the effective medium's critical angle for total internal reflection and show that the transmission through the multilayer structure depends strongly on nanoscale variations even at layer thicknesses smaller than ?/50. In such deep subwavelength structures, we demonstrate dramatic changes in the transmission for variations in properties such as periodicity, order of the layers, and their parity. In addition to its conceptual importance, such sensitivity has important potential applications in sensing and switching. PMID:25541773

  19. Thermal stability of Mo\\/Si multilayers

    Microsoft Academic Search

    Robert S. Rosen; Michael A. Viliardos; M. E. Kassner; Daniel G. Stearns; Stephen P. Vernon

    1992-01-01

    The thermal stability of Mo\\/Si multilayers for x-ray mirror applications was investigated by annealing studies at relatively low temperatures for various times. The as-deposited and annealed multilayers were examined using conventional small and large angle x-ray diffraction, normal incidence x-ray reflectance measurements using a synchrotron source, selected area electron diffraction, and high-resolution electron microscopy. The as-deposited structure consists of pure

  20. Laterally graded multilayer double-monochromator.

    SciTech Connect

    Als-Nielsen, J.; Erdmann, J.; Gaarde, P.; Krasnicki, S.; Liu, C.; Macrander, A. T.; Maj, J.; Mancini, D.

    1999-09-01

    The authors describe a tunable multilayer monochromator with an adjustable bandpass to be used for reflectivity and grazing incidence diffraction studies on surfaces at energies near 10 keV. Multilayers have a bandpass typically 100 times larger than the Si(111) reflection, and by using multilayers an experimenter can significantly increase data collection rates over those available with a Si monochromator. The transmission through 1 and 2 laterally graded multilayer (LGML) reflections was recorded versus photon energy. The identical LGMLs were comprised of 60 bilayers of W and C on 100 x 25 x 3 mm float glass with a bilayer spacing varying from 35 to 60 {angstrom}. The average gradient was 0.27 {angstrom}/mm along the long dimension. The rms deviation of the data for the bilayer spacing from a linear fit was 0.36 {angstrom}. Data were obtained for a nondispersive ({+-}) double-multilayer arrangement. The relative bandpass width (FWHM) when the two multilayers exposed the same bilayer spacing was measured to be 2.2% with a transmission of 78.7 {+-} 1.6%. This value is consistent with the transmission of 88.9% that they also measured for a single LGML at HASYLAB beamline D4. The bandpass was tunable in the range 1.1% to 2.2%.

  1. Capability of etched multilayer EUV mask fabrication

    NASA Astrophysics Data System (ADS)

    Takai, Kosuke; Murano, Koji; Kamo, Takashi; Morikawa, Yasutaka; Hayashi, Naoya

    2014-09-01

    Recently, development of next generation extremely ultraviolet lithography (EUVL) equipment with high-NA (Numerical Aperture) optics for less than hp10nm node is accelerated. Increasing magnification of projection optics or mask size using conventional mask structure has been studied, but these methods make lithography cost high because of low through put and preparing new large mask infrastructures. To avoid these issues, etched multilayer EUV mask has been proposed. As a result of improvement of binary etched multilayer mask process, hp40nm line and space pattern on mask (hp10nm on wafer using 4x optics) has been demonstrated. However, mask patterns are easily collapsed by wet cleaning process due to their low durability caused by high aspect ratio. We propose reducing the number of multilayer pairs from 40 to 20 in order to increase durability against multilayer pattern collapse. With 20pair multilayer blank, durable minimum feature size of isolated line is extended from 80nm to 56nm. CD uniformity and linearity of 20pair etched multilayer pattern are catching up EUV mask requirement of 2014.

  2. Trapping atoms using nanoscale quantum vacuum forces

    PubMed Central

    Chang, D. E.; Sinha, K.; Taylor, J. M.; Kimble, H. J.

    2014-01-01

    Quantum vacuum forces dictate the interaction between individual atoms and dielectric surfaces at nanoscale distances. For example, their large strengths typically overwhelm externally applied forces, which makes it challenging to controllably interface cold atoms with nearby nanophotonic systems. Here we theoretically show that it is possible to tailor the vacuum forces themselves to provide strong trapping potentials. Our proposed trapping scheme takes advantage of the attractive ground-state potential and adiabatic dressing with an excited state whose potential is engineered to be resonantly enhanced and repulsive. This procedure yields a strong metastable trap, with the fraction of excited-state population scaling inversely with the quality factor of the resonance of the dielectric structure. We analyse realistic limitations to the trap lifetime and discuss possible applications that might emerge from the large trap depths and nanoscale confinement. PMID:25008119

  3. Nanoscale plasmonic memristor with optical readout functionality.

    PubMed

    Emboras, Alexandros; Goykhman, Ilya; Desiatov, Boris; Mazurski, Noa; Stern, Liron; Shappir, Joseph; Levy, Uriel

    2013-01-01

    We experimentally demonstrate for the first time a nanoscale resistive random access memory (RRAM) electronic device integrated with a plasmonic waveguide providing the functionality of optical readout. The device fabrication is based on silicon on insulator CMOS compatible approach of local oxidation of silicon, which enables the realization of RRAM and low optical loss channel photonic waveguide at the same fabrication step. This plasmonic device operates at telecom wavelength of 1.55 ?m and can be used to optically read the logic state of a memory by measuring two distinct levels of optical transmission. The experimental characterization of the device shows optical bistable behavior between these levels of transmission in addition to well-defined hysteresis. We attribute the changes in the optical transmission to the creation of a nanoscale absorbing and scattering metallic filament in the amorphous silicon layer, where the plasmonic mode resides. PMID:24256313

  4. Nanoscale plasmonic stamp lithography on silicon.

    PubMed

    Liu, Fenglin; Luber, Erik J; Huck, Lawrence A; Olsen, Brian C; Buriak, Jillian M

    2015-02-24

    Nanoscale lithography on silicon is of interest for applications ranging from computer chip design to tissue interfacing. Block copolymer-based self-assembly, also called directed self-assembly (DSA) within the semiconductor industry, can produce a variety of complex nanopatterns on silicon, but these polymeric films typically require transformation into functional materials. Here we demonstrate how gold nanopatterns, produced via block copolymer self-assembly, can be incorporated into an optically transparent flexible PDMS stamp, termed a plasmonic stamp, and used to directly functionalize silicon surfaces on a sub-100 nm scale. We propose that the high intensity electric fields that result from the localized surface plasmons of the gold nanoparticles in the plasmonic stamps upon illumination with low intensity green light, lead to generation of electron-hole pairs in the silicon that drive spatially localized hydrosilylation. This approach demonstrates how localized surface plasmons can be used to enable functionalization of technologically relevant surfaces with nanoscale control. PMID:25654172

  5. Silicon epitaxy in nanoscale for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Yoo, Jinkyoung; Nguyen, Binh-Minh; Dayeh, Shadi A.; Schuele, Paul; Evans, David; Picraux, S. T.

    2014-09-01

    Nanostructures provide novel opportunities of studying epitaxy in nano/mesoscale and on nonplanar substrates. Epitaxial growth of silicon (Si) on the surfaces of Si nanowires along radial direction is a promising way to prepare radial p-(i)-n junction in nanoscale for optoelectronic devices. Comprehensive studies of Si radial epitaxy in micro/nanoscale reveal that morphological evolution and size-dependent radial shell growth rate for undoped and doped Si radial shells. Single crystalline Si radial p-i-n junction wire arrays were utilized to fabricate photovoltaic (PV) devices. The PV devices exhibited the photoconversion efficiency of 10%, the short-circuit current density of 39 mA/cm2, and the open-circuit voltage of 0.52 V, respectively.

  6. Light-driven nanoscale plasmonic motors

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Zentgraf, Thomas; Liu, Yongmin; Bartal, Guy; Zhang, Xiang

    2010-08-01

    When Sir William Crookes developed a four-vaned radiometer, also known as the light-mill, in 1873, it was believed that this device confirmed the existence of linear momentum carried by photons, as predicted by Maxwell's equations. Although Reynolds later proved that the torque on the radiometer was caused by thermal transpiration, researchers continued to search for ways to take advantage of the momentum of photons and to use it for generating rotational forces. The ability to provide rotational force at the nanoscale could open up a range of applications in physics, biology and chemistry, including DNA unfolding and sequencing and nanoelectromechanical systems. Here, we demonstrate a nanoscale plasmonic structure that can, when illuminated with linearly polarized light, generate a rotational force that is capable of rotating a silica microdisk that is 4,000 times larger in volume. Furthermore, we can control the rotation velocity and direction by varying the wavelength of the incident light to excite different plasmonic modes.

  7. Programmed assembly of nanoscale structures using peptoids.

    SciTech Connect

    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.

  8. CMOS compatible nanoscale nonvolatile resistance switching memory.

    PubMed

    Jo, Sung Hyun; Lu, Wei

    2008-02-01

    We report studies on a nanoscale resistance switching memory structure based on planar silicon that is fully compatible with CMOS technology in terms of both materials and processing techniques employed. These two-terminal resistance switching devices show excellent scaling potential well beyond 10 Gb/cm2 and exhibit high yield (99%), fast programming speed (5 ns), high on/off ratio (10(3)), long endurance (10(6)), retention time (5 months), and multibit capability. These key performance metrics compare favorably with other emerging nonvolatile memory techniques. Furthermore, both diode-like (rectifying) and resistor-like (nonrectifying) behaviors can be obtained in the device switching characteristics in a controlled fashion. These results suggest that the CMOS compatible, nanoscale Si-based resistance switching devices may be well suited for ultrahigh-density memory applications. PMID:18217785

  9. MoRu/Be multilayers for extreme ultraviolet applications

    DOEpatents

    Bajt, Sasa C. (Livermore, CA); Wall, Mark A. (Stockton, CA)

    2001-01-01

    High reflectance, low intrinsic roughness and low stress multilayer systems for extreme ultraviolet (EUV) lithography comprise amorphous layers MoRu and crystalline Be layers. Reflectance greater than 70% has been demonstrated for MoRu/Be multilayers with 50 bilayer pairs. Optical throughput of MoRu/Be multilayers can be 30-40% higher than that of Mo/Be multilayer coatings. The throughput can be improved using a diffusion barrier to make sharper interfaces. A capping layer on the top surface of the multilayer improves the long-term reflectance and EUV radiation stability of the multilayer by forming a very thin native oxide that is water resistant.

  10. Study of wetting properties of Ti/TiN liners deposited by ion metal plasma PVD for low-temperature sub-0.25-um Al fill technology

    NASA Astrophysics Data System (ADS)

    Hui, Simon; Ngan, Ken; Narasimhan, Murali K.; Hogan, Barry; Yao, Gongda; Ramaswami, Sesh

    1997-09-01

    Ti/TiN liners deposited with Vectra IMPTM (Ion Metal Plasma) PVD technology can be used as wetting layers to lower the temperature of Al planarization. The Ti/TiN liners can also be used to improve the texture and morphology of the Al overlayer. An experimental investigation was performed to study the impact of the IMP PVD process on the wetting properties of the Ti/TiN films. The Ti/TiN underlayers and the Al overlayer were studied for film morphology and texturing using AFM, XRD, and TEM techniques. It was found that the IMP Ti/TiN process can be used to control and optimize the fill capabilities of low temperature Al planarization. Parameters such as process pressure, bias, process temperature of the IMP Ti and TiN process as well as the wetting layer thickness have significant effects on the grain size, reflectivity, crystal orientation, and surface roughness of the aluminum films. Al films with high reflectivity, low roughness and hyper texturing (< 1 degree(s) FWHM) have been obtained with the integration of IMP Ti/TiN liner module with a low temperature Al planarization module. The fill capability of this integrated process exceeds that of the conventional high temperature Al planarization process at the Via level for a sub 0.25 micrometers IC process.

  11. Nanoscale Science, Engineering and Technology Research Directions

    SciTech Connect

    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.

  12. Nanoscale thermal transport. II. 2003-2012

    NASA Astrophysics Data System (ADS)

    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 analysis using proximal probes has achieved spatial resolution of 10 nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

  13. Center for Nanoscale Science and Technology

    NSDL National Science Digital Library

    The Center for Nanoscale Science and Technology consists of a Research Program and the Nanofab, a shared-use facility providing economical access to state-of-the-art nanofabrication and nano-measurement tools. The CNST Nanofab is now available for use by non-NIST users. See "What we do", to the left, for a description of CNST and its Research Program as well as the CNST Nanofab and its use policies.

  14. Electromagnetic simulations for nanoscale RF blocks

    Microsoft Academic Search

    Wil H. A. Schilders; L. Miguel Silveira; Jorge Fernández Villena

    2007-01-01

    Next-generation nano-scale RFIC designs have an unprecedented complexity and performance that will inevitably lead to costly re-spins and loss of market opportunities. In order to cope with this, efficient and accurate models of interconnects, integrated inductors, the substrate and devices, together with their mutual interactions, need to be developed. The key idea is that integrated devices can no longer be

  15. Self-healing at the nanoscale

    Microsoft Academic Search

    Vincenzo Amendola; Moreno Meneghetti

    2009-01-01

    The design of self-healing materials is a very important but challenging topic in nanotechnology. Self-healing strategies, also inspired by natural processes, allow the fabrication of auto-repairing systems, and in recent years, materials engineering at the nanoscale has allowed further advances in this emerging field. In this mini review, we recall some interesting self-healing systems found in natural processes and others

  16. Nanoscale structures and mechanics of barnacle cement

    Microsoft Academic Search

    Ruby May A. Sullan; Nikhil Gunari; Adrienne E. Tanur; Yuri Chan; Gary H. Dickinson; Beatriz Orihuela; Dan Rittschof; Gilbert C. Walker

    2009-01-01

    Polymerized barnacle glue was studied by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and chemical staining. Nanoscale structures exhibiting rod-shaped, globular and irregularly-shaped morphologies were observed in the bulk cement of the barnacle Amphibalanus amphitrite (=Balanus amphitrite) by AFM. SEM coupled with energy dispersive X-ray (EDX) provided chemical composition information, making evident the organic

  17. Nanoscale thermal transport. II. 2003–2012

    SciTech Connect

    Cahill, David G., E-mail: d-cahill@illinois.edu; Braun, Paul V. [Department of Materials Science and Engineering and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Chen, Gang [Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139 (United States); Clarke, David R. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Fan, Shanhui [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Goodson, Kenneth E. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Keblinski, Pawel [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); King, William P. [Department of Mechanical Sciences and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Mahan, Gerald D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Majumdar, Arun [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Maris, Humphrey J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Phillpot, Simon R. [Department of Materials Science and Engineering, University of Florida, Gainseville, Florida 32611 (United States); Pop, Eric [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Shi, Li [Department of Mechanical Engineering, University of Texas, Autin, Texas 78712 (United States)

    2014-03-15

    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 analysis using proximal probes has achieved spatial resolution of 10?nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

  18. Module Four - The Uniqueness of the Nanoscale

    NSDL National Science Digital Library

    This module covers the unique attributes of the nano-scale and some examples of these unique attributes, including small size, high surface to volume ratio, surface forces in relation to bulk forces, quantum mechanical effects, and wave properties of light. This module is from the Nanotechnology Applications and Career Knowledge (NACK), a National ATE Center. This site requires a free log-in to access.

  19. Nanoscale Materials Modification for Device Applications

    Microsoft Academic Search

    Robert G. Elliman

    This chapter considers device applications of ion beams that involve nanoscale modification of materials. It is necessarily\\u000a selective and does not include broad classes of applications such as ion beam assisted deposition of thin films or tribological\\u000a modification of surfaces for improved wear, corrosion resistance or biocompatibility. Instead it aims to illustrate the diversity\\u000a of ion beam applications by providing

  20. Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum

    NSDL National Science Digital Library

    Amy Taylor

    2008-03-01

    Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three activities following an adapted learning cycle model are suggested for student exploration of three properties of the nanoscale: bumpy, sticky, and shaky.

  1. Multilayer contactless dielectrophoresis: theoretical considerations.

    PubMed

    Sano, Michael B; Salmanzadeh, Alireza; Davalos, Rafael V

    2012-07-01

    Dielectrophoresis (DEP), the movement of dielectric particles in a nonuniform electric field, is of particular interest due to its ability to manipulate particles based on their unique electrical properties. Contactless DEP (cDEP) is an extension of traditional and insulator-based DEP topologies. The devices consist of a sample channel and fluid electrode channels filled with a highly conductive media. A thin insulating membrane between the sample channel and the fluid electrode channels serves to isolate the sample from direct contact with metal electrodes. Here we investigate, for the first time, the properties of multilayer devices in which the sample and electrode channels occupy distinct layers. Simulations are conducted using commercially available finite element software and a less computationally demanding numerical approximation is presented and validated. We show that devices can be created that achieve a similar level of electrical performance to other cDEP devices presented in the literature while increasing fluid throughput. We conclude, based on these models, that the ultimate limiting factors in device performance resides in breakdown voltage of the barrier material and the ability to generate high-voltage, high-frequency signals. Finally, we demonstrate trapping of MDA-MB-231 breast cancer cells in a prototype device at a flow rate of 1.0 mL/h when 250 V(RMS) at 600 kHz is applied. PMID:22806458

  2. Systematic modification of the rheological properties of colloidal suspensions with polyelectrolyte multilayers

    NASA Astrophysics Data System (ADS)

    Hess, Andreas; Pretzl, Melanie; Heymann, Lutz; Fery, Andreas; Aksel, Nuri

    2011-09-01

    Tailoring rheological properties of colloidal suspensions with the adsorption of polyelectrolyte multilayers (PEMs) is based on the idea of controlling macroscopic mechanical properties by modifying the particle surface in a reproducible and well-understood manner. With layer-by-layer self-assembly, monodisperse polystyrene particles are coated with up to ten layers of the oppositely charged strong polyelectrolytes: poly(diallyl dimethyl ammonium chloride) and poly(styrene sulfonate). The conformation of the adsorbed polyelectrolyte is controlled by the ionic strength of the used aqueous polyelectrolyte solution. For 1M NaCl solution, a brushlike adsorption of the polyelectrolyte is expected. The ability of PEMs to serve on a nanoscale level as surface modifiers and influence macroscopic rheological properties like viscoelasticity, yield stress, and shear banding is discussed. The mechanical behavior of these suspensions is qualitatively described by the theory of Derjaguin-Landau-Verwey-Overbeek with short-range repulsion and long-range attraction. A scaling rule is proposed which distinguishes between the precusor and the multilayer regime.

  3. Absence of a ferromagnetic phase in pure Ge quantum dots and Ge/SiO2 multilayer films

    NASA Astrophysics Data System (ADS)

    Chi, Y. C.; Chao, J. H.

    2014-08-01

    Quantum magnetism is currently one of the most challenging areas of materials science. Research efforts have been concentrated on studying the onset of the nano-scale systems that are originally non-magnetic in bulk forms. Recently, claims of the existence of Ge-based ferromagnetism in pure Ge quantum dots and Ge/SiO2 multilayer films have attracted certain attention from the scientific world. However, if both Ge quantum dots and Ge/SiO2 multilayer films were able to form ordered magnetic states without the contribution of extrinsic inclusions, the induced ferromagnetism would be certainly incompatible with our knowledge of magnetism in physics. We therefore reinitiate an investigation in order to examine the validity of their claims. Unfortunately, our results have shown that neither pure Ge quantum dots nor Ge/SiO2 multilayer films were able to exhibit ferromagnetism. The ferromagnetism of the “ferromagnetic Ge” was most likely originated from contaminants, such as Fe and Ni and not from Ge.

  4. Novel materials, computational spectroscopy, and multiscale simulation in nanoscale photovoltaics

    E-print Network

    Bernardi, Marco, Ph. D. Massachusetts Institute of Technology

    2013-01-01

    Photovoltaic (PV) solar cells convert solar energy to electricity using combinations of semiconducting sunlight absorbers and metallic materials as electrical contacts. Novel nanoscale materials introduce new paradigms for ...

  5. Tailorable stimulated Brillouin scattering in nanoscale silicon waveguides

    E-print Network

    Shin, Heedeuk

    Nanoscale modal confinement is known to radically enhance the effect of intrinsic Kerr and Raman nonlinearities within nanophotonic silicon waveguides. By contrast, stimulated Brillouin-scattering nonlinearities, which ...

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

    DOEpatents

    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. Plastic behavior of Cu/Ni multilayers

    SciTech Connect

    Verdier, M.; Hawley, M.; Nastasi, M.; Kung, H. [Los Alamos National Lab., NM (United States); Niewczas, M. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering; Embury, J.D. [Los Alamos National Lab., NM (United States)]|[McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

    1998-12-31

    In order to study the plasticity in Cu-Ni multilayers deposited on single crystals of nanoindentation measurements, and by the transmission of well characterized dislocations from the underlying substrate by tensile deformation of Cu single crystals. Various multilayers were deposited by physical vapor deposition with layer thicknesses varying between 1,000 and 20 Angstroms (for a total thickness between 0.8 and 1 {micro}m). Two types of experiments were designed. The first one aimed at injecting, in a controlled way, some dislocations from the substrate into the multilayers; the second type of experiment concerned the structure of the multilayer surface after having plastically pushed the material away from a nanoindenter. This communication reports the results from the nanoindentation measurements, as well as the observations of slip on the surface. The authors observed through the injection of dislocations by nanoindentation that the multilayers increase in strength with refinement of the layer structure but at thicknesses below 35 {angstrom} exhibits a softening behavior. Also observation of the upheaval around the nanoindent showed an evolution from slip lines to more spread plasticity with refinement of the layer structure.

  8. Determining Multilayer Formation Properties from Transient Temperature and Pressure Measurements

    E-print Network

    Sui, Weibo

    2010-10-12

    The Multilayer Transient Test is a well-testing technique designed to determine formation properties in multiple layers, and it has been proved effective during the past two decades. To apply the Multilayer Transient Test, a combination of rate...

  9. TECHNIQUES: THE MULTI-LAYER PERCEPTRON Back propagation

    E-print Network

    Bressler, Steven L.

    TECHNIQUES: THE MULTI-LAYER PERCEPTRON Learning Back propagation The General Multi-Layer PerceptronScript demonstration of learning in a single-layer perceptron. #12;In MLPs, learning is supervised, with separate

  10. Layer-by-layer assembly of {nanoclay-(sol-gel oxide)}n and {nanoclay-(oxide nanoparticle)}n multilayers: Synthesis and growth mechanisms

    NASA Astrophysics Data System (ADS)

    Chen, Hao

    Two new classes of all-inorganic nanostructured multilayers, {MMT x-(sol-gel oxide)}n and {MMTx-(oxide nanoparticle)} n, have been successfully synthesized for the first time. They were made by adapting a layer-by-layer (LbL) assembly method initially developed to synthesize polyelectrolyte-based multilayers. In most previous studies, this electrostatic-assisted LbL assembly method used polyelectrolytes/polymers as the "structural glue" to prepare multilayers. The synthesis of {MMTx-(sol-gel ZrO2)}n multilayers demonstrates for the first time the feasibility of making sol-gel oxide "glued" all-inorganic multilayers, thereby introducing an innovative nanoscale fabrication concept. The synthesis of {MMTx-(oxide nanoparticle)}n multilayers further illustrates the versatility of LbL assembly technique by achieving a second new type of all-inorganic multilayers with a novel "plate-ball" architecture. The feasibility of synthesizing other types of multilayer structures, including {MMTx-(ionic liquid)}n, {(carbon nanotube)-(sol-gel ZrO2)}n, and {polymer-(sol-gel ZrO2)} n, were also explored. Systematical investigations of the growth kinetics of {MMTx-(sol-gel ZrO2)}n multilayers reveal unique underlying mechanisms for electrostatic-assisted growth of sol-gel films and LbL assembly. The growth of the MMT and sol-gel ZrO2 layers is strongly coupled. For fresh aqueous ZrO2 precursors, the growth rates of sol-gel ZrO2 layers on MMT surfaces as functions of time and precursor concentration do not follow the standard mass transfer or interfacial reaction controlled kinetic models. Furthermore, the growth of the sol-gel oxide layers on MMT surfaces is self-limited to a maximum thickness of ˜50-60 nm. These observations suggest a surface-mediated growth of sol-gel 'oxide layers on MMT surfaces, one that is likely controlled by electrostatic interactions. These new findings significantly advance the general understanding of the LbL electrostatic assembly process. For the aged precursors, the growth mechanism differs; the growth of sol-gel oxide layers is controlled by hydrodynamics and follows the Landau-Levich model. For as-deposited multilayers, isothermal annealing at ˜400°C dehydrates them and removes the residue acetate groups without damaging the MMT nanoplatelets and the ordered layer structures. Nanomechanical measurements show that the elastic modulus of the multilayers can be intentionally tuned by changing the multilayer design and that significant porosity is present in the multilayers even after annealing. In addition, free-standing multilayers are successfully made via using sacrificial substrates, and the newly developed methodology for {MMTx-(sol-gel oxide)} n can be extended, using other metal oxides, e.g., SnO2, as the inorganic "glue." Potential applications of these new nanostructured multilayers are discussed.

  11. Maximum screening fields of superconducting multilayer structures

    NASA Astrophysics Data System (ADS)

    Gurevich, Alex

    2015-01-01

    It is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields Hs of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ˜0.1 ?m at the Nb surface could increase Hs ? 240 mT of a clean Nb up to Hs ? 290 mT. Optimized multilayers of Nb3Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surface of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.

  12. Using Visualization Techniques in Multilayer Traffic Modeling

    NASA Astrophysics Data System (ADS)

    Bragg, Arnold

    We describe visualization techniques for multilayer traffic modeling - i.e., traffic models that span several protocol layers, and traffic models of protocols that cross layers. Multilayer traffic modeling is challenging, as one must deal with disparate traffic sources; control loops; the effects of network elements such as IP routers; cross-layer protocols; asymmetries in bandwidth, session lengths, and application behaviors; and an enormous number of complex interactions among the various factors. We illustrate by using visualization techniques to identify relationships, transformations, and scaling; to smooth simulation and measurement data; to examine boundary cases, subtle effects and interactions, and outliers; to fit models; and to compare models with others that have fewer parameters. Our experience suggests that visualization techniques can provide practitioners with extraordinary insight about complex multilayer traffic effects and interactions that are common in emerging next-generation networks.

  13. Transmission fingerprints in quasiperiodic magnonic multilayers

    NASA Astrophysics Data System (ADS)

    Coelho, I. P.; Vasconcelos, M. S.; Bezerra, C. G.

    2011-12-01

    In this paper we investigated the influence of mirror symmetry on the transmission spectra of quasiperiodic magnonic multilayers arranged according to Fibonacci, Thue-Morse and double period quasiperiodic sequences. We consider that the multilayers composed of two simple cubic Heisenberg ferromagnets with bulk exchange constants JA and JB and spin quantum numbers SA and SB, respectively. The multilayer structure is surrounded by two semi-infinite slabs of a third Heisenberg ferromagnetic material with exchange constant JC and spin quantum number SC. For simplicity, the lattice constant has the same value a in each material, corresponding to epitaxial growth at the interfaces. The transfer matrix treatment was used for the exchange-dominated regime, taking into account the random phase approximation (RPA). Our numerical results illustrate the effects of mirror symmetry on (i) transmission spectra and (ii) transmission fingerprints.

  14. Imaging Schwarzschild multilayer X-ray microscope

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Baker, Phillip C.; Shealy, David L.; Core, David B.; Walker, Arthur B. C., Jr.; Barbee, Troy W., Jr.; Kerstetter, Ted

    1993-01-01

    We have designed, analyzed, fabricated, and tested Schwarzschild multilayer X-ray microscopes. These instruments use flow-polished Zerodur mirror substrates which have been coated with multilayers optimized for maximum reflectivity at normal incidence at 135 A. They are being developed as prototypes for the Water Window Imaging X-Ray Microscope. Ultrasmooth mirror sets of hemlite grade sapphire have been fabricated and they are now being coated with multilayers to reflect soft X-rays at 38 A, within the biologically important 'water window'. In this paper, we discuss the fabrication of the microscope optics and structural components as well as the mounting of the optics and assembly of the microscopes. We also describe the optical alignment, interferometric and visible light testing of the microscopes, present interferometrically measured performance data, and provide the first results of optical imaging tests.

  15. Apodization of multilayer bulk-wave transducers.

    PubMed

    Akcakaya, E; Adler, E L; Farnell, G W

    1989-01-01

    Recent experiments have demonstrated the use of superlattice transducers for bulk acoustic waves in the gigahertz frequency range. The transducers consisted of multilayers of ZnO or LiNbO(3) with alternating crystal orientations or polarizations. A procedure for calculating the electromechanical characteristics of general multilayer transducers in which the individual layers are anisotropic and piezoelectric and have arbitrary crystal orientation is described. The algorithm used is numerically stable and easily implemented for use on a personal computer using commercial software. A network model is also derived to provide both an approximate analysis of multilayer transducer performance and an insight into synthesis procedures. Examples are used to compare the two approaches and illustrate an initial design procedure for broadband transducers. PMID:18290243

  16. High Spectral Resolution With Multilayer Gratings

    SciTech Connect

    Andre, J.-M.; Le Guen, K.; Jonnard, P. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France)

    2010-04-06

    The improvement of spectral resolution brought about by the use of multilayer grating (MG) instead of multilayer mirror (MM) is analyzed. The spectrum of a complex sample containing various elements excited under electron irradiation is studied. This sample is a pellet made by pressing powders of Cu and compounds with Fe and F atoms. The MM is a Mo/B{sub 4}C periodic multilayer with a period of about 6 nm; for the MG a grating of 1 {mu}m period has been etched in the MM. It is shown that the MG can easily resolve the F Kalpha and Fe Lalpha emissions, separated by about 30 eV, whereas the MM is unable to give such a performance. A comparison with an EDS (SDD) detector is also given. It is also shown that the MG can improve the detection limit. Finally the role of the slit placed in front of the detector is discussed.

  17. Optimized capping layers for EUV multilayers

    DOEpatents

    Bajt, Sasa (Livermore, CA); Folta, James A. (Livermore, CA); Spiller, Eberhard A. (Livermore, CA)

    2004-08-24

    A new capping multilayer structure for EUV-reflective Mo/Si multilayers consists of two layers: A top layer that protects the multilayer structure from the environment and a bottom layer that acts as a diffusion barrier between the top layer and the structure beneath. One embodiment combines a first layer of Ru with a second layer of B.sub.4 C. Another embodiment combines a first layer of Ru with a second layer of Mo. These embodiments have the additional advantage that the reflectivity is also enhanced. Ru has the best oxidation resistance of all materials investigated so far. B.sub.4 C is an excellent barrier against silicide formation while the silicide layer formed at the Si boundary is well controlled.

  18. Investigation of multilayer magnetic domain lattice file

    NASA Technical Reports Server (NTRS)

    Torok, E. J.; Kamin, M.; Tolman, C. H.

    1980-01-01

    The feasibility of the self structured multilayered bubble domain memory as a mass memory medium for satellite applications is examined. Theoretical considerations of multilayer bubble supporting materials are presented, in addition to the experimental evaluation of current accessed circuitry for various memory functions. The design, fabrication, and test of four device designs is described, and a recommended memory storage area configuration is presented. Memory functions which were demonstrated include the current accessed propagation of bubble domains and stripe domains, pinning of stripe domain ends, generation of single and double bubbles, generation of arrays of coexisting strip and bubble domains in a single garnet layer, and demonstration of different values of the strip out field for single and double bubbles indicating adequate margins for data detection. All functions necessary to develop a multilayer self structured bubble memory device were demonstrated in individual experiments.

  19. Multilayer perceptrons: Approximation order and necessary number of hidden units

    E-print Network

    Trenn, Stephan

    1 Multilayer perceptrons: Approximation order and necessary number of hidden units Stephan Trenn--multilayer perceptron, approximation, necessary number of hidden units I. INTRODUCTION The original motivation the biological background and historical remarks are given. In this paper only the multilayer perceptron (MLP

  20. Enhanced Robustness of Multilayer Perceptron Training Walter H. Delashmit

    E-print Network

    Manry, Michael

    Enhanced Robustness of Multilayer Perceptron Training Walter H. Delashmit Lockheed Martin Missiles Department Arlington, TX 76011 Abstract Due to the chaotic nature of multilayer perceptron training, training of the problem When different size (different numbers of hidden units) multilayer perceptrons (MLPs

  1. Swelling Behavior of Hyaluronic Acid/Polyallylamine Hydrochloride Multilayer Films

    E-print Network

    Barrett, Christopher

    of the polyelectrolytes in the multilayer assemblies, measured by the potential, on colloidal particles. The films were multilayer thin films is based upon the fact that the adsorption of the polyelectrolyte chains leadsSwelling Behavior of Hyaluronic Acid/Polyallylamine Hydrochloride Multilayer Films Susan E. Burke

  2. Swelling Dynamics of Multilayer Films of Weak Polyelectrolytes

    E-print Network

    Barrett, Christopher

    Swelling Dynamics of Multilayer Films of Weak Polyelectrolytes Oleh M. Tanchak and Christopher J.1 Thin polyelectrolyte multilayer (PEM) films fabricated by this layer-by-layer (LbL) adsorption of thin polyelectrolyte multilayers assembled from poly(acrylic acid) and poly(allylamine hydrochloride

  3. Yield stress and scaling of polyelectrolyte multilayer modified suspensions: effect of polyelectrolyte conformation during multilayer assembly.

    PubMed

    Hess, Andreas; Aksel, Nuri

    2013-09-10

    The yield stress of polyelectrolyte multilayer modified suspensions exhibits a surprising dependence on the polyelectrolyte conformation of multilayer films. The rheological data scale onto a universal master curve for each polyelectrolyte conformation as the particle volume fraction, ?, and the ionic strength of the background fluid, I, are varied. It is shown that rough films with highly coiled, brushy polyelectrolytes significantly enhance the yield stress. Moreover, via the ionic strength I of the background fluid, the dynamic yield stress of brushy polyelectrolyte multilayers can be finely adjusted over 2 decades. PMID:23952570

  4. EDITORIAL: Light Control at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Kral, Petr; Shapiro, Moshe

    2007-06-01

    It is customary to denote as 'nano-systems' entities whose size varies between 1 and 100 nm. Such systems span an immense variety of structures, ranging from large molecules, quantum dots, and nanowires, to viruses. Their existence is based on, and accompanied by, an amazing abundance of phenomena, depending on a huge number of parameters, all of which can in principle be used for nanoscale control. One of the most potent means of controlling nano-systems is light: it can serve as a tool for the addressing, preparation, stabilization and excitation of nano-systems. Design of light control scenarios is based on the laser techniques of coherent and optimal control at wavelengths and time sequencing most appropriate to the nano-systems, or on more traditional, incoherent forms of light-matter interactions. This special issue of Journal of Physics B: Atomic, Molecular and Optical Physics (J. Phys. B) devoted to the subject of light control at the nanoscale contains a collection of articles that cover several key areas in this fast-growing field. These include: preparation and manipulation of nano-systems by light, nanoscale plasmonics and spintronics, Bose-Einstein condensation and excitation of novel molecular and crystalline systems. We have grouped the papers according to these general areas. The guest editors gratefully acknowledge the help of the staff of J. Phys. B, especially that of Alice Malhador from the editorial team, and Adrian Corrigan from production, in preparing this issue, and Professor Jan-Michel Rost, the Editor-in-Chief, for his support of this project.

  5. Dustiness of Fine and Nanoscale Powders

    PubMed Central

    Evans, Douglas E.; Baron, Paul A.

    2013-01-01

    Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3–37.9% and 0.1–31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300nm to several micrometers, but no modes below 100nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100nm particle contribution in a workplace. PMID:23065675

  6. Dustiness of fine and nanoscale powders.

    PubMed

    Evans, Douglas E; Turkevich, Leonid A; Roettgers, Cynthia T; Deye, Gregory J; Baron, Paul A

    2013-03-01

    Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3-37.9% and 0.1-31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300 nm to several micrometers, but no modes below 100 nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace. PMID:23065675

  7. Synthesis and electrical conductivity of multilayer silicene

    SciTech Connect

    Vogt, P., E-mail: patrick.vogt@tu-berlin.de, E-mail: bruno.grandidier@isen.iemn.univ-lille1.fr; Bruhn, T. [Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin (Germany); Capiod, P.; Berthe, M.; Grandidier, B., E-mail: patrick.vogt@tu-berlin.de, E-mail: bruno.grandidier@isen.iemn.univ-lille1.fr [Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520 Département ISEN, 41 bd Vauban, 59046 Lille Cedex (France); Resta, A. [Aix-Marseille University, CNRS-CINaM, Campus de Luminy, Case 913, F-13288 Marseille Cedex 09 (France); De Padova, P. [Instituto di Struttura della Materia, Consiglio Nazionale delle Ricerche - ISM, via Fosso del Cavaliere, 00133 Roma (Italy); Le Lay, G. [Aix-Marseille University, CNRS-CINaM, Campus de Luminy, Case 913, F-13288 Marseille Cedex 09 (France); Instituto di Struttura della Materia, Consiglio Nazionale delle Ricerche - ISM, via Fosso del Cavaliere, 00133 Roma (Italy)

    2014-01-13

    The epitaxial growth and the electrical resistance of multilayer silicene on the Ag(111) surface has been investigated. We show that the atomic structure of the first silicene layer differs from the next layers and that the adsorption of Si induces the formation of extended silicene terraces surrounded by step bunching. Thanks to the controlled contact formation between the tips of a multiple probe scanning tunneling microscope and these extended terraces, a low sheet resistance, albeit much higher than the electrical resistance of the underlying silver substrate, has been measured, advocating for the electrical viability of multilayer silicene.

  8. Evidence of Dirac fermions in multilayer silicene

    NASA Astrophysics Data System (ADS)

    De Padova, Paola; Vogt, Patrick; Resta, Andrea; Avila, Jose; Razado-Colambo, Ivy; Quaresima, Claudio; Ottaviani, Carlo; Olivieri, Bruno; Bruhn, Thomas; Hirahara, Toru; Shirai, Terufusa; Hasegawa, Shuji; Carmen Asensio, Maria; Le Lay, Guy

    2013-04-01

    Multilayer silicene, the silicon analogue of multilayer graphene, grown on silver (111) surfaces, possesses a honeycomb (?3 × ?3)R30° reconstruction, observed by scanning tunnelling microscopy at room temperature, past the initial formation of the dominant, 3×3 reconstructed, silicene monolayer. For a few layers silicene film we measure by synchrotron radiation photoelectron spectroscopy, a cone-like dispersion at the Brillouin zone centre due to band folding. ?* and ? states meet at ˜0.25 eV below the Fermi level, providing clear evidence of the presence of gapless Dirac fermions.

  9. Dynamic visualization of nanoscale vortex orbits.

    PubMed

    Timmermans, Matias; Samuely, Tomas; Raes, Bart; Van de Vondel, Joris; Moshchalkov, Victor V

    2014-03-25

    Due to the atomic-scale resolution, scanning tunneling microscopy is an ideal technique to observe the smallest objects. Nevertheless, it suffers from very long capturing times in order to investigate dynamic processes at the nanoscale. We address this issue, for vortex matter in NbSe2, by driving the vortices using an ac magnetic field and probing the induced periodic tunnel current modulations. Our results reveal different dynamical modes of the driven vortex lattices. In addition, by recording and synchronizing the time evolution of the tunneling current at each pixel, we visualize the overall dynamics of the vortex lattice with submillisecond time resolution and subnanometer spatial resolution. PMID:24460428

  10. Nanoscale atomic waveguides with suspended carbon nanotubes

    E-print Network

    V. Peano; M. Thorwart; A. Kasper; R. Egger

    2005-11-23

    We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.

  11. Synthesis, dynamics and photophysics of nanoscale systems

    NASA Astrophysics Data System (ADS)

    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 through a combination of steady-state and time-resolved spectroscopy in conjunction with quantum chemical calculations aided in the elucidation of the dynamics and the mechanism of light harvesting in the multichromophoric phycobiliprotein phycocyanin PC645 in vitro. Investigation of the light-harvesting efficiency and optimization of energy transfer with respect to the structural organization of light-harvesting chromophores on the nanoscale, can provide us with fundamental information necessary for the development of synthetic light-harvesting devices capable of mimicking the efficiency of the natural system.

  12. Size-Dependent Accuracy of Nanoscale Thermometers.

    PubMed

    Alicki, Robert; Leitner, David M

    2014-10-01

    The accuracy of two classes of nanoscale thermometers is estimated in terms of size and system-dependent properties using the spin-boson model. We consider solid state thermometers, where the energy splitting is tuned by thermal properties of the material, and fluorescent organic thermometers, in which the fluorescence intensity depends on the thermal population of conformational states of the thermometer. The results of the theoretical model compare well with the accuracy reported for several nanothermometers that have been used to measure local temperature inside living cells. PMID:25260146

  13. Nanoscale Synthesis and Functional Assembly Center for Nanophase Materials

    E-print Network

    Pennycook, Steve

    ; Optical, structural and electrical characterization of carbon-based nanomaterials; Charge transport study, sensors. Optical and optoelectronic characterization of organic semiconductor materials (small molecules materials; #12;3. Inorganic/organic nanoscale electronics. Fabrication 1D and 2D nanoscale electronic

  14. Nanoscale Physics The Wiess School of Natural Sciences

    E-print Network

    Richards-Kortum, Rebecca

    and Fabrication at the Nanoscale (F) PHYS 537 Methods of Experimental Physics I (F) PHYS534NanostructuresandNanotechnologyII(S such as quantum behavior of nanostructures, quantum nanotechnology, nanoscale imaging, and the fabrication Spectroscopy (F) ELEC 603 Nano-optics and Nanophotonics (F) ELEC 685 Fundamentals of Medical Imaging (F) ENGI

  15. Technology Review: Nanoscale Inkjet Printing TechnologyReview.

    E-print Network

    Rogers, John A.

    Technology Review: Nanoscale Inkjet Printing My. TechnologyReview. com: > Login > Register Home, 2007 Nanoscale Inkjet Printing E-jet printing of precise structures out of various materials could prove to be a valuable tool in nano manufacturing. By Duncan Graham-Rowe q Print q E-mail q Audio » New

  16. Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum

    ERIC Educational Resources Information Center

    Taylor, Amy; Jones, Gail; Pearl, Thomas P.

    2008-01-01

    Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three…

  17. Design and Performance Analysis of Nanoscale Content-Addressable Memories

    E-print Network

    Slatton, Clint

    Design and Performance Analysis of Nanoscale Content- Addressable Memories Bryan Davis, Jose, 32611, USA Abstract -- This paper proposes a nanoscale content addressable memory (CAM) architecture made by Kuekes et al prove correct about the potential size of their memory, this CAM may be a valuable

  18. Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy

    ERIC Educational Resources Information Center

    Bogle, Stephanie Nicole

    2009-01-01

    Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…

  19. Method to determine thermal profiles of nanoscale circuitry

    DOEpatents

    Zettl, Alexander K; Begtrup, Gavi E

    2013-04-30

    A platform that can measure the thermal profiles of devices with nanoscale resolution has been developed. The system measures the local temperature by using an array of nanoscale thermometers. This process can be observed in real time using a high resolution imagining technique such as electron microscopy. The platform can operate at extremely high temperatures.

  20. Essential physics of carrier transport in nanoscale MOSFETs

    Microsoft Academic Search

    Mark Lundstrom; Zhibin Ren

    2002-01-01

    The device physics of nanoscale MOSFETs is explored by numerical simulations of a model transistor. The physics of charge control, source velocity saturation due to thermal injection, and scattering in ultrasmall devices are examined. The results show that the essential physics of nanoscale MOSFETs can be understood in terms of a conceptually simple scattering model

  1. Exciton-Plasmon States in Nanoscale Materials: Breakdown of the

    E-print Network

    Marini, Andrea

    Exciton-Plasmon States in Nanoscale Materials: Breakdown of the Tamm-Dancoff Approximation Myrta propagating only forward in time. However, we show that in nanoscale materials excitons and plasmons hybridize, creating exciton-plasmon states where the electron-hole pairs oscillate back and forth in time. Then

  2. Programmable Resistance Switching in Nanoscale Two-Terminal Devices

    Microsoft Academic Search

    Sung Hyun Jo; Kuk-Hwan Kim; Wei Lu

    2009-01-01

    We show that in nanoscale two-terminal resistive switches the resistance switching can be dominated by the formation of a single conductive filament. The probabilistic filament formation process strongly affects the device operation principle, and can be programmed to facilitate new functionalities such as multibit switching with partially formed filaments. In addition, the nanoscale switches exhibit excellent performance metrics making them

  3. Preparation and characterization on nano-hybrid composite solid polymer electrolyte of PVdF-HFP /MG49-ZrO{sub 2} for battery application

    SciTech Connect

    Lee, T. K.; Ahmad, A. [Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor D. E. Malaysia and School of Chemical Sciences and Food Technology, Faculty of Science and Technology (Malaysia); Hasyareeda, N. [School of Chemical Sciences and Food Technology, Faculty of Science and Technology (Malaysia)

    2014-09-03

    Initial study on nano composite polymer electrolyte of PVdF-HFP/MG49-ZrO{sub 2} has been done. The zirconium was synthesis via in-situ sol-gel method in a dissolved polymer blends. The effects of different concentrations of zirconium and pH values have been investigated on nano composite polymer (NCP). Analysis impedance show that only at 6 wt. % of zirconium for all pH values show a semi-circle arc which have lowest value of bulk resistance. No ionic conductivity value is obtain due to the absent of ion charge carriers. Analysis of XRD revealed that crystallinity phase of the nano composite polymer was affect by different pH values. However, no significant changes have been observed in IR bands. This could well indicate that different pH medium did not affect the chemical bonding in the structure.

  4. Impact of ethylene carbonate on ion transport characteristics of PVdF-AgCF{sub 3}SO{sub 3} polymer electrolyte system

    SciTech Connect

    Austin Suthanthiraraj, S.; Joice Sheeba, D., E-mail: jsheebaj@sify.com [Department of Energy, University of Madras, Guindy Campus, Chennai 600025 (India); Joseph Paul, B., E-mail: joe_paul82@yahoo.co.in [Department of Energy, University of Madras, Guindy Campus, Chennai 600025 (India)

    2009-07-01

    The ionic transport in thin film plasticized polymer electrolytes based on polyvinylidene fluoride (PVdF) as the polymer host, silver triflate (AgCF{sub 3}SO{sub 3}) as salt and ethylene carbonate (EC) as plasticizer prepared by solution casting technique has been reported. Addition of silver triflate has resulted in an increase in the room temperature (298 K) electrical conductivity of the polymer from 10{sup -6} to 10{sup -5} S cm{sup -1} whereas incorporation of EC as the plasticizer has further enhanced the conductivity value by an order of magnitude to 10{sup -4} S cm{sup -1} owing to the possible decrease in crystallinity of the polymer matrix as revealed by the detailed temperature-dependent complex impedance, silver ionic transference number, Fourier transform infrared and X-ray diffraction measurements.

  5. Nano-Scale Effects in Cylindrical Contacts Sari et al. NANO-SCALE EFFECTS IN THE ADHERENCE, SLIDING

    E-print Network

    Müftü, Sinan

    @coe.neu.edu Abstract The behavior of a nano-scale cylindrical body (e.g. a fiber), lying on a substrate and acted uponNano-Scale Effects in Cylindrical Contacts Sari et al. 1 NANO-SCALE EFFECTS IN THE ADHERENCE to the nano level, adhesion becomes an important issue in this contact problem. Thus this investigation treats

  6. Precise surface measurements at the nanoscale

    NASA Astrophysics Data System (ADS)

    Fedina, L. I.; Sheglov, D. V.; Kosolobov, S. S.; Gutakovskii, A. K.; Latyshev, A. V.

    2010-05-01

    Availability of self-assembly effects occurring at the atomically clean Si(1 1 1) surface during high temperature anneals in an ultrahigh vacuum chamber for fabrication of a precise calibrator at nanoscale measurements is discussed. These effects provide formation of ordered monatomic step arrays assembled by step bunches divided by almost singular surface areas with widely spaced monatomic steps suitable for calibration of atomic force microscopes. The monatomic step height at the Si(1 1 1) surface and its replication by the native oxide layer was attested by the high-resolution transmission electron microscopy followed by Digital Micrograph analysis and found to be equal to interplanar spacing (0.314 nm) in the volume of Si crystal with ±0.001 nm of accuracy. Excellent replication of the monatomic step height by oxide film covering the Si surface makes available precise AFM calibration at the nanoscale at ambient conditions. The averaged step height measured by AFM scanning of 1 × 1 µm2 is found to be 0.314 ± 0.003 nm (~1% of uncertainty). However, when the scan area becomes bigger than 2 × 2 µm2, the height measurement uncertainty increases sharply 15 times (0.310 ± 0.034 nm). We assume that this is due to differences between piezo element calibrations at small and large scan areas. The height measurement uncertainty for step bunches with well-defined quantity of steps (28) even at a large scan area (18 × 18 µm2) turns out to be 0.3%.

  7. Convex lens-induced nanoscale templating

    PubMed Central

    Berard, Daniel J.; Michaud, François; Mahshid, Sara; Ahamed, Mohammed Jalal; McFaul, Christopher M. J.; Leith, Jason S.; Bérubé, Pierre; Sladek, Rob; Reisner, Walter; Leslie, Sabrina R.

    2014-01-01

    We demonstrate a new platform, convex lens-induced nanoscale templating (CLINT), for dynamic manipulation and trapping of single DNA molecules. In the CLINT technique, the curved surface of a convex lens is used to deform a flexible coverslip above a substrate containing embedded nanotopography, creating a nanoscale gap that can be adjusted during an experiment to confine molecules within the embedded nanostructures. Critically, CLINT has the capability of transforming a macroscale flow cell into a nanofluidic device without the need for permanent direct bonding, thus simplifying sample loading, providing greater accessibility of the surface for functionalization, and enabling dynamic manipulation of confinement during device operation. Moreover, as DNA molecules present in the gap are driven into the embedded topography from above, CLINT eliminates the need for the high pressures or electric fields required to load DNA into direct-bonded nanofluidic devices. To demonstrate the versatility of CLINT, we confine DNA to nanogroove and nanopit structures, demonstrating DNA nanochannel-based stretching, denaturation mapping, and partitioning/trapping of single molecules in multiple embedded cavities. In particular, using ionic strengths that are in line with typical biological buffers, we have successfully extended DNA in sub–30-nm nanochannels, achieving high stretching (90%) that is in good agreement with Odijk deflection theory, and we have mapped genomic features using denaturation analysis. PMID:25092333

  8. Light-driven nanoscale plasmonic motors.

    PubMed

    Liu, Ming; Zentgraf, Thomas; Liu, Yongmin; Bartal, Guy; Zhang, Xiang

    2010-08-01

    When Sir William Crookes developed a four-vaned radiometer, also known as the light-mill, in 1873, it was believed that this device confirmed the existence of linear momentum carried by photons, as predicted by Maxwell's equations. Although Reynolds later proved that the torque on the radiometer was caused by thermal transpiration, researchers continued to search for ways to take advantage of the momentum of photons and to use it for generating rotational forces. The ability to provide rotational force at the nanoscale could open up a range of applications in physics, biology and chemistry, including DNA unfolding and sequencing and nanoelectromechanical systems. Here, we demonstrate a nanoscale plasmonic structure that can, when illuminated with linearly polarized light, generate a rotational force that is capable of rotating a silica microdisk that is 4,000 times larger in volume. Furthermore, we can control the rotation velocity and direction by varying the wavelength of the incident light to excite different plasmonic modes. PMID:20601945

  9. Visualizing copper assisted graphene growth in nanoscale

    PubMed Central

    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

  10. Visualizing copper assisted graphene growth in nanoscale.

    PubMed

    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 sp(2) 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

  11. Visualizing copper assisted graphene growth in nanoscale

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  12. Constructal heat trees at micro and nanoscales

    NASA Astrophysics Data System (ADS)

    Gosselin, Louis; Bejan, Adrian

    2004-11-01

    We consider the problem of cooling a two-dimensional heat generating conducting volume with one heat sink, such that the smallest features of the internal structure are so small that the conventional description of conduction breaks down. The effective thermal conductivity exhibits the "size effect," and is governed by the smallest structural dimension, which is comparable with the mean free path of the energy carriers. According to the constructal method, the development of the internal cooling structure proceeds from small to large, in steps of geometric optimization and assembly. This starts at the elemental level, where there is only one high-conductivity layer for collecting and evacuating the heat. The shape of the smallest volume can be optimized for minimal thermal resistance. Next, a first construct is formed by optimizing the number of assembled elements and the internal geometric features of the assembly. The method is repeated at the second construct level, where several first constructs are grouped so that their global thermal resistance is minimal. The construction reveals an internal multiscale structure shaped as a tree, where the spaces between the smallest branches are ruled by nanoscale heat transfer. It is shown that the transition from regions with nanoscale heat transfer to regions with conventional heat transfer is governed not only by the smallest dimensions, but also by heterogeneity (relative amounts of high- and low-conductivity materials).

  13. Nanoscale phenomena in synthetic functional oxide heterostructures.

    PubMed

    Nagarajan, V; Ganpule, C S; Stanishevsky, A; Liu, B T; Ramesh, R

    2002-08-01

    This paper reviews nanoscale phenomena such as polarization relaxation dynamics and piezoelectric characterization in model ferroelectric thin films and nanostructures using voltage-modulated scanning force microscopy. Using this technique we show the three-dimensional reconstruction of the polarization vector in lead zirconate titanate (PZT) thin films. Second, the time-dependent relaxation of remanent polarization in epitaxial PZT ferroelectric thin films, containing a uniform two-dimensional grid of 90 degrees domains (c-axis in the plane of the film), has been investigated extensively. The 90 degrees domain walls preferentially nucleate the 180 degrees reverse domains during relaxation. Relaxation occurs through the nucleation and growth of reverse 180 degrees domains, which subsequently coalesce and consume the entire region as a function of relaxation time. In addition we also present results on investigation of the relaxation phenomenon on a very local scale, where pinning and bowing of domain walls has been observed. We also show how this technique is used for obtaining quantitative information on piezoelectric constants and by engineering special structures, and how we realize ultrahigh values of piezoconstants. Last, we also show direct hysteresis measurements on nanoscale capacitors, where there is no observable loss of polarization in capacitors as small as 0.16 microm2 in area. PMID:12533230

  14. Nanoscale Charge Transport in Excitonic Solar Cells

    SciTech Connect

    Venkat Bommisetty, South Dakota State University

    2011-06-23

    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. Poroelasticity of Cartilage at the Nanoscale

    PubMed Central

    Nia, Hadi Tavakoli; Han, Lin; Li, Yang; Ortiz, Christine; Grodzinsky, Alan

    2011-01-01

    Atomic-force-microscopy-based oscillatory loading was used in conjunction with finite element modeling to quantify and predict the frequency-dependent mechanical properties of the superficial zone of young bovine articular cartilage at deformation amplitudes, ?, of ?15 nm; i.e., at macromolecular length scales. Using a spherical probe tip (R ? 12.5 ?m), the magnitude of the dynamic complex indentation modulus, |E?|, and phase angle, ?, between the force and tip displacement sinusoids, were measured in the frequency range f ? 0.2–130 Hz at an offset indentation depth of ?0 ? 3 ?m. The experimentally measured |E?| and ? corresponded well with that predicted by a fibril-reinforced poroelastic model over a three-decade frequency range. The peak frequency of phase angle, fpeak, was observed to scale linearly with the inverse square of the contact distance between probe tip and cartilage, 1/d2, as predicted by linear poroelasticity theory. The dynamic mechanical properties were observed to be independent of the deformation amplitude in the range ? = 7–50 nm. Hence, these results suggest that poroelasticity was the dominant mechanism underlying the frequency-dependent mechanical behavior observed at these nanoscale deformations. These findings enable ongoing investigations of the nanoscale progression of matrix pathology in tissue-level disease. PMID:22067171

  16. Semi-analytical solutions for multilayer reservoirs

    E-print Network

    Lolon, Elyezer Pabibak

    2001-01-01

    Intercept Case 3 aj + bj tD Linear p[wDj(tD)] Case 4 a[j] exp(bj tD) Exponential p[wDj(tD)] Case 5 General formulation: p[wsD(tD)] = [] Total Pressure/Rate Averaging} Our work illustrates the validity of each approximate multilayer solution...

  17. Curved silicon substrates for multilayer structures

    Microsoft Academic Search

    R. C. Woodbury; H. Fan; L. V. Knight; J. M. Thorne

    1986-01-01

    Two-dimensional curved surfaces, which may be suitable for x-ray reflective lenses of the multilayer type, have been produced using polished single crystal (110) silicon wafers. The curvature was achieved using stressed thin films of grown silicon dioxide and deposited silicon nitride. In addition to basic experimental studies with planer structures to determine stress values and predictive equations, the paper describes

  18. Mechanical properties of Nanotubes of Polyelectrolyte Multilayers

    E-print Network

    Boyer, Edmond

    for the Young's modulus of these nanostructures, well below the values reported for dry, flat multilayers Louvain-la-Neuve, Belgium. List of the authors: Stéphane Cuenot (corresponding author): 1 Institut des to 200 nm. The elastic modulus of the nanotubes was computed from the resonance frequencies

  19. Scattering cancellation by metamaterial cylindrical multilayers

    Microsoft Academic Search

    Simone Tricarico; Filiberto Bilotti; Lucio Vegni

    2009-01-01

    In this paper, we present the theoretical analysis and the design of cylindrical multilayered electromagnetic cloaks based on the scattering cancellation technique. We propose at first the analysis and the design of bi-layered cylindrical shells, made of homogenous and isotropic metamaterials, in order to effectively reduce the scattered field from a dielectric cylindrical object. The single shell and the bi-layered

  20. Efficient Block Training of Multilayer Perceptrons

    Microsoft Academic Search

    Angel Navia-vázquez; Aníbal R. Figueiras-vidal

    2000-01-01

    The attractive possibility of applying layerwise block training algorithms to multilayer perceptrons MLP, which offers initial advantages in computational effort, is refined in this article by means of introducing a sensitivity correction factor in the formulation. This results in a clear performance advantage, which we verify in several applications. The reasons for this advantage are discussed and related to implicit

  1. Scattering and absorption by spherical multilayer particles

    NASA Astrophysics Data System (ADS)

    Sinzig, J.; Quinten, M.

    1994-02-01

    We present a recursion formalism for the scattering coefficients of multilayered spherical particles which is more treatable for computer programs than the matrixformalism of Bhandari [1]. We computed explicitely the extinction and scattering cross section spectra of different metal coated spheres. Comparison with experimental results is done for gold-silver heterosystems. The spectra are in very good agreement with the experimental data.

  2. Spatial dispersion of multilayer fishnet metamaterials

    E-print Network

    Spatial dispersion of multilayer fishnet metamaterials Sergey S. Kruk, David A. Powell, Alexander," Phys. Rev. B 74, 075103 (2006). 4. M. A. Noginov, Yu. A. Barnakov, G. Zhu, T. Tumkur, H. Li, and E. E. 9. J. Valentine, S. Zhang, T. Zentgraf, E. Ulin-Avila, D. A. Genov, G. Bartal, and X. Zhang, "Three

  3. Thermal expansion properties of thin multilayer films

    NASA Astrophysics Data System (ADS)

    Cheng, Xianchao; Morawe, Christian; Peffen, Jean-Christophe; Zhang, Lin

    2014-09-01

    Under synchrotron radiation white beam exposure, strong mechanical stress can build up in multilayer optics, caused by the thermal mismatch between layer material and substrate material. To study the stability and performance of multilayer optics under heat load, Pd, Cr, and B4C single layers of thicknesses in the nanometer range and [Pd/B4C] multilayers were prepared in the sputter-depositing facility of the ESRF Multilayer Laboratory. Curvature changes versus temperature were measured using a Shack-Hartmann wave front sensor. Films coated on 200 ?m thin Si wafers induced significant curvature changes over a temperature range from 60°C to 200°C. A combined parameter K including Young's modulus and thermal expansion coefficient (CTE) was defined to describe the thermal deformation properties of the thin-film layer. The investigation shows that all three materials in thin film cause less thermal expansion than expected from material properties for bulk material in the literature. In particular, the thermal expansion of B4C films appears to be close to that of the Si substrate.

  4. A New Model for Multilayer Ceramic Composites

    Microsoft Academic Search

    A. Dey; P. Dey; S. Datta; A. K. Mukhopadhyay

    2008-01-01

    An attempt was made in the present work, to develop a model for design of multilayer ceramic composites (MLC) with high failure energy. The model considered the failure process of a notched MLC beam comprised of N number of matrix layers of thickness tm each, separated by (N ? 1) very thin interfacial layer of thickness ti (?tm) and loaded in a

  5. A Molecular Walk Across Polyelectrolyte Multilayers

    Microsoft Academic Search

    Houssam W. Jomaa

    2005-01-01

    Polyelectrolyte multilayers are formed by alternate deposition of polyelectrolyte solutions of opposite charges onto a charged surface. The film produced can be very well controlled in terms of thickness and composition. The conditions of buildup, polyelectrolytes used, and post assembly treatment all contribute into giving these systems distinctive qualities and characteristics. Interfacial science, between the disciplines of biology and chemistry

  6. Delamination of multilayer thermal barrier coatings

    Microsoft Academic Search

    Sung Ryul Choi; John W. Hutchinson; A. G. Evans

    1999-01-01

    Multilayer thermal barrier coatings (TBCs) on superalloy substrates are comprised of an intermetallic bond coat, a thermally grown oxide (TGO) layer, and a porous zirconia top coat that provides thermal protection. The TGO attains a thickness of 1–10 ?m prior to failure, while the bond coat and zirconia layer are each about 50–100 ?m thick. The preferred method for manufacturing

  7. Domain Walls in Antiferromagnetically Coupled Multilayer Films

    Microsoft Academic Search

    Olav Hellwig; Andreas Berger; Eric E. Fullerton

    2003-01-01

    We report experimentally observed magnetic domain-wall structures in antiferromagnetically coupled multilayer films with perpendicular anisotropy. Our studies reveal a first-order phase transition from domain walls with no net moment to domain walls with ferromagnetic cores. The transition originates from the competition between dipolar and exchange energies, which we tune by means of layer thickness. Although observed in a synthetic antiferromagnetic

  8. Computational Study of Polyelectrolyte Multilayer Films

    Microsoft Academic Search

    Bewerse Steven J

    2011-01-01

    Experimentalists have found that the growth of polyelectrolyte multilayer films are not always linear and can be exponential. The size of these films is very important in applications such as photovoltaics where exact depths are needed for ideal power eifficiency. This work is a computational study of such growth, attempting to find which conditions (such as length of the polyelectrolyte

  9. Multilayer fluid dynamics of immiscible liquids

    NASA Technical Reports Server (NTRS)

    Koster, Jean N.

    1994-01-01

    A comprehensive analytical, numerical and experimental study of convective flow in multilayer immiscible liquids has been performed. Studies include transparent high Prandtl number of liquid as well as opaque low Prandtl metallic melts. A new radioscopic flow visualization has been developed for the latter studies.

  10. PREFACE: Superconductivity in ultrathin films and nanoscale systems Superconductivity in ultrathin films and nanoscale systems

    NASA Astrophysics Data System (ADS)

    Bianconi, Antonio; Bose, Sangita; Garcia-Garcia, Antonio Miguel

    2012-12-01

    The recent technological developments in the synthesis and characterization of high-quality nanostructures and developments in the theoretical techniques needed to model these materials, have motivated this focus section of Superconductor Science and Technology. Another motivation is the compelling evidence that all new superconducting materials, such as iron pnictides and chalcogenides, diborides (doped MgB2) and fullerides (alkali-doped C60 compounds), are heterostrucures at the atomic limit, such as the cuprates made of stacks of nanoscale superconducting layers intercalated by different atomic layers with nanoscale periodicity. Recently a great amount of interest has been shown in the role of lattice nano-architecture in controlling the fine details of Fermi surface topology. The experimental and theoretical study of superconductivity in the nanoscale started in the early 1960s, shortly after the discovery of the BCS theory. Thereafter there has been rapid progress both in experiments and the theoretical understanding of nanoscale superconductors. Experimentally, thin films, granular films, nanowires, nanotubes and single nanoparticles have all been explored. New quantum effects appear in the nanoscale related to multi-component condensates. Advances in the understanding of shape resonances or Fano resonances close to 2.5 Lifshitz transitions near a band edge in nanowires, 2D films and superlattices [1, 2] of these nanosized modules, provide the possibility of manipulating new quantum electronic states. Parity effects and shell effects in single, isolated nanoparticles have been reported by several groups. Theoretically, newer techniques based on solving Richardson's equation (an exact theory incorporating finite size effects to the BCS theory) numerically by path integral methods or solving the entire Bogoliubov-de Gennes equation in these limits have been attempted, which has improved our understanding of the mechanism of superconductivity in these confined systems. In addition, the role of thermodynamic fluctuations on superconducting properties has been extensively studied in the context of nanoparticles and nanowires both experimentally and theoretically. In the past decade, a lot of work has been initiated in the area of interface superconductivity where different techniques have been demonstrated to tune Tc. Although the progress in this field has deepened our understanding of nanoscale superconductors, there are several open and key questions which need to be addressed. Some of these are: (1) can superconductivity be enhanced and Tc increased in nanostructures with respect to the bulk limit and if so, how can it be controlled? (2) What are the theoretical and experimental limits for the enhancement and control of superconductivity? (3) Can the phenomena identified in conventional nanostructures shed light on phenomena in high Tc superconductors and vice versa? (4) How will the new fundamental physics of superconductivity at the nanoscale promote advances in nanotechnology applications and vice versa? The papers in this focus section reflect the advances made in this field, in particular in nanowires and nanofilms, but also attempt to answer some of the key open questions outlined above. The theoretical papers explore unconventional quantum phenomena such as the role of confinement in the dynamics of single Cooper pairs in isolated grains [1] and Fano resonances in superconducting gaps in multi-condensate superconductors near a 2.5 Lifshitz transition [2]. Here a new emerging class of quantum phenomena of fundamental physics appear at the Bose-BCS crossover in multi-condensate superconductors [2]. Nanosize effects can now be manipulated by controlling defects in layered oxides [3]. A new approach is provided by controlling the self-organization of oxygen interstitials in layered copper oxides that show an intrinsic nanoscale phase separation [4]. In this case a non-trivial distribution of superconducting nanograins appears to enhance the critical temperature [4]. This is a hot topic as in the past year many wo

  11. Transformation of chlorinated methanes by nanoscale iron particles

    SciTech Connect

    Lien, H.L.; Zhang, W.X.

    1999-11-01

    This paper examines the potential of using laboratory-synthesized nanoscale iron particles to transform chlorinated methanes. The iron particles have diameters on the order of 1--100 nm. Palladized iron particles were prepared by depositing palladium on the surface of iron. Batch experiments were conducted to compare reactions of chlorinated methanes with palladized nanoscale iron, nanoscale iron, and commercial grade iron particles. Rapid transformations of tetrachloromethane (CT) and trichloromethane (CF) were achieved with the palladized nanoscale iron particles. Typically 0.1 mM CT or CF was reduced below detection limits within 1 h. Methane and dichloromethane (DCM) were the major end products. Yields of methane and DCM from CT were 52% and 23%, respectively. Little degradation of DCM was observed within 72 h. With the nanoscale iron and commercial-grade iron particles, much slower reactions of chlorinated methanes were observed. Kinetic analyses indicated that the surface area-normalized rate coefficients k{sub SA} of the nanoscale iron and commercial grade iron particles were one to two orders of magnitude lower than those of the palladized nanoscale iron.

  12. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Tenne, Dmitri

    2007-03-01

    Conventional vibrational spectroscopies operating in visible and infrared range fail to measure the phonon spectra of nanoscale ferroelectric structures because of extremely weak signals and the overwhelming substrate contribution. In this talk, application of ultraviolet (UV) Raman spectroscopy for studies of lattice dynamics and ferroelectric phase transitions in nanoscale ferroelectrics will be presented. We demonstrate that UV Raman spectroscopy is an effective technique allowing the observation of phonons and determination of the ferroelectric phase transition temperature (Tc) in nanoscale ferroelectrics, specifically, BaTiO3/SrTiO3 superlattices having the ferroelectric BaTiO3 layers as thin as 1 unit cell, and single BaTiO3 layers as thin as 4 nm. BaTiO3/SrTiO3 superlattices and ultrathin BaTiO3 films studied were grown by molecular beam epitaxy on SrTiO3 as well as GdScO3 and DyScO3 substrates. Excellent epitaxial quality and atomically abrupt interfaces are evidenced by X-ray diffraction and high resolution transmission electron microscopy. UV Raman results show that one-unit-cell thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are ferroelectric with the Tc as high as 250 K, and induce the polarization in much thicker SrTiO3 layers adjacent to them. The Tc in superlattices was tuned by hundreds of degrees from ˜170 to 650 K by varying the thicknesses of BaTiO3 and SrTiO3 layers. Using scandate substrates enables growth of superlattices with systematically changed coherent strain, thus allowing studying the stress effect on the ferroelectric phase transitions. UV Raman data are supported by the thermodynamic calculations of polarization in superlattices as a function of temperature. The work was done in collaboration with A. Soukiassian, W. Tian, D.G. Schlom, Y.L. Li, L.-Q. Chen, X.X. Xi (Pennsylvania State University), A. Bruchhausen, A. Fainstein (Centro Atomico Bariloche & Instituto Balseiro, Argentina), R. S. Katiyar (University of Puerto Rico), A. Cantarero (University of Valencia, Spain), K.J. Choi, D.M. Kim, C.-B. Eom (University of Wisconsin), H.P. Sun, X.Q. Pan (University of Michigan), S.M. Nakhmanson; K.M. Rabe (Rutgers University), Q.X. Jia (Los Alamos National Laboratory)

  13. Biosynthesis of calcium hydroxylapatite coating on sputtered Ti/TiN nano multilayers and their corrosion behavior in simulated body solution.

    PubMed

    Subramanian, Balasubramanian; Dhandapani, Perumal; Maruthamuthu, Sundaram; Jayachandran, Muthirulandi

    2012-02-01

    Titanium/titanium nitride (Ti/TiN) nanoscale multilayered films were deposited onto 316L stainless steel substrates by reactive magnetron sputtering using a Ti target. Coatings characterized by X-ray diffraction showed that the stack possesses centered cubic structure. The X-ray photoelectron spectroscopy survey spectra on the etched surfaces of the stack film on steel exhibited the characteristic Ti2p, N1s, and O1s peaks at the corresponding binding energies 454.5, 397.0, and 530.6 eV, respectively. Platelet adhesion experiments were carried out to examine the interaction between blood and the materials in vitro. The results indicated that the smoothness and lower isoelectric point contribute to better hemocompatibility of the Ti/TiN nanoscale multilayered coating. The biomediated synthesis of calcium hydroxylapatite (HA) was carried out on coated substrates using calcium-depositing bacteria. The observation of low corrosion current density (I(corr)) for the calcium HA-coated Ti/TiN specimens in simulated body fluid confirmed their highly resistive nature under the testing condition. PMID:20819919

  14. Refractive index of nanoscale thickness films measured by Brewster refractometry

    E-print Network

    Tikhonov, E A; Malyukin, Yu V

    2015-01-01

    It is shown that reflective laser refractometery at Brewster angle can be usefull for precision measurements of refractive indexes (RI) in the transparency band of various films of nanoscale thickness. The RI measurements of nanoscale porous film on the basis of gadolinium orthosilicate and quartz have been carried out as first experience. It is shown that surface light scattering in such films that is connected with clustering of nanoscale pores can decrease the accuracy of the RI measurements at Brewster angle. Estimated physical dependence RI stipulated by the film thickness reduction (3D-2D transition) in the range of (20-160)nm has not been not detected.

  15. Method to adjust multilayer film stress induced deformation of optics

    DOEpatents

    Spiller, Eberhard A. (Mount Kisco, NY); Mirkarimi, Paul B. (Sunol, CA); Montcalm, Claude (Livermore, CA); Bajt, Sasa (Sunol, CA); Folta, James A. (Livermore, CA)

    2000-01-01

    Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

  16. Bayesian localisation microscopy reveals nanoscale podosome dynamics

    PubMed Central

    Cox, Susan; Rosten, Edward; Monypenny, James; Jovanovic-Talisman, Tijana; Burnette, Dylan T.; Lippincott-Schwartz, Jennifer; Jones, Gareth E.; Heintzmann, Rainer

    2011-01-01

    We demonstrate a localization microscopy analysis method that is able to extract results in live cells using standard fluorescent proteins and Xenon arc lamp illumination. Our Bayesian analysis of blinking and bleaching (3B analysis) method models the entire dataset simultaneously as being generated by a number of fluorophores which may or may not be emitting light at any given time. The resulting technique allows many overlapping fluorophores in each frame, and unifies the analysis of localization from blinking and bleaching events. By modeling the entire dataset we are able to use each reappearance of a fluorophore to improve the localization accuracy. The high performance of this technique allows us to reveal the nanoscale dynamics of podosome formation and dissociation with a resolution of 50 nm on a four second timescale. PMID:22138825

  17. Carbon-bearing fluids at nanoscale interfaces

    SciTech Connect

    Cole, David [Ohio State University; Ok, Salim [Ohio State University, Columbus; Phan, A [Ohio State University, Columbus; Rother, Gernot [ORNL; Striolo, Alberto [Oklahoma University; Vlcek, Lukas [ORNL

    2013-01-01

    The behaviour of fluids at mineral surfaces or in confined geometries (pores, fractures) typically differs from their bulk behaviour in many ways due to the effects of large internal surfaces and geometrical confinement. We summarize research performed on C-O-H fluids at nanoscale interfaces in materials of interest to the earth and material sciences (e.g., silica, alumina, zeolites, clays, rocks, etc.), emphasizing those techniques that assess microstructural modification and/or dynamical behaviour such as gravimetric analysis, small-angle (SANS) neutron scattering, and nuclear magnetic resonance (NMR). Molecular dynamics (MD) simulations will be described that provide atomistic characterization of interfacial and confined fluid behaviour as well as aid in the interpretation of the neutron scattering results.

  18. Preface: Charge transport in nanoscale junctions

    NASA Astrophysics Data System (ADS)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-01

    Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at the molecular level. Nanoscale charge transport experiments in ionic liquids extend the field to high temperatures and to systems with intriguing interfacial potential distributions. Other directions may include dye-sensitized solar cells, new sensor applications and diagnostic tools for the study of surface-bound single molecules. Another motivation for this special issue is thus to highlight activities across different research communities with nanoscale charge transport as a common denominator. This special issue gathers 27 articles by scientists from the United States, Germany, the UK, Denmark, Russia, France, Israel, Canada, Australia, Sweden, Switzerland, the Netherlands, Belgium and Singapore; it gives us a flavour of the current state-of-the-art of this diverse research area. While based on contributions from many renowned groups and institutions, it obviously cannot claim to represent all groups active in this very broad area. Moreover, a number of world-leading groups were unable to take part in this project within the allocated time limit. Nevertheless, we regard the current selection of papers to be representative enough for the reader to draw their own conclusions about the current status of the field. Each paper is original and has its own merit, as all papers in Journal of Physics: Condensed Matter special issues are subjected to the same scrutiny as regular contributions. The Guest Editors have deliberately not defined the specific subjects covered in this issue. These came out logically from the development of this area, for example: 'Traditional' solid state nanojunctions based on adsorbed layers, oxide films or nanowires sandwiched between two electrodes: effects of molecular structure (aromaticity, anchoring groups), symmetry, orientation, dynamics (noise patterns) and current-induced heating. Various 'physical effects': inelastic tunnelling and Coulomb blockade, polaron effects, switching modes, and negative differential resistance; the role of many particle excitations, new surface states in semiconductor electrodes, various mechanisms for

  19. Exploring Carbon Nanotubes for Nanoscale Devices

    NASA Technical Reports Server (NTRS)

    Han, Jie; Dai; Anantram; Jaffe; Saini, Subhash (Technical Monitor)

    1998-01-01

    Carbon nanotubes (CNTs) are shown to promise great opportunities in nanoelectronic devices and nanoelectromechanical systems (NEMS) because of their inherent nanoscale sizes, intrinsic electric conductivities, and seamless hexagonal network architectures. I present our collaborative work with Stanford on exploring CNTs for nanodevices in this talk. The electrical property measurements suggest that metallic tubes are quantum wires. Furthermore, two and three terminal CNT junctions have been observed experimentally. We have proposed and studied CNT-based molecular switches and logic devices for future digital electronics. We also have studied CNTs based NEMS inclusing gears, cantilevers, and scanning probe microscopy tips. We investigate both chemistry and physics based aspects of the CNT NEMS. Our results suggest that CNT have ideal stiffness, vibrational frequencies, Q-factors, geometry-dependent electric conductivities, and the highest chemical and mechanical stabilities for the NEMS. The use of CNT SPM tips for nanolithography is presented for demonstration of the advantages of the CNT NEMS.

  20. Apparatus for producing nanoscale ceramic powders

    DOEpatents

    Helble, Joseph J. (Andover, MA); Moniz, Gary A. (Windham, NH); Morse, Theodore F. (Little Compton, RI)

    1997-02-04

    An apparatus provides high temperature and short residence time conditions for the production of nanoscale ceramic powders. The apparatus includes a confinement structure having a multiple inclined surfaces for confining flame located between the surfaces so as to define a flame zone. A burner system employs one or more burners to provide flame to the flame zone. Each burner is located in the flame zone in close proximity to at least one of the inclined surfaces. A delivery system disposed adjacent the flame zone delivers an aerosol, comprising an organic or carbonaceous carrier material and a ceramic precursor, to the flame zone to expose the aerosol to a temperature sufficient to induce combustion of the carrier material and vaporization and nucleation, or diffusion and oxidation, of the ceramic precursor to form pure, crystalline, narrow size distribution, nanophase ceramic particles.

  1. Apparatus for producing nanoscale ceramic powders

    DOEpatents

    Helble, Joseph J. (Andover, MA); Moniz, Gary A. (Windham, NH); Morse, Theodore F. (Little Compton, RI)

    1995-09-05

    An apparatus provides high temperature and short residence time conditions for the production of nanoscale ceramic powders. The apparatus includes a confinement structure having a multiple inclined surfaces for confining flame located between the surfaces so as to define a flame zone. A burner system employs one or more burners to provide flame to the flame zone. Each burner is located in the flame zone in close proximity to at least one of the inclined surfaces. A delivery system disposed adjacent the flame zone delivers an aerosol, comprising an organic or carbonaceous carrier material and a ceramic precursor, to the flame zone to expose the aerosol to a temperature sufficient to induce combustion of the carrier material and vaporization and nucleation, or diffusion and oxidation, of the ceramic precursor to form pure, crystalline, narrow size distribution, nanophase ceramic particles.

  2. Virtual Journal of Nanoscale Science and Technology

    NSDL National Science Digital Library

    Featured here is an important subscription-based resource for obtaining science articles online. Wide-ranging institutional access as well as free services make this resources useful without an individual subscription. In addition, in January 2000, the American Institute of Physics (AIP) and the American Physical Society (APS) launched a new virtual journal. Representing the first entry in a series of journals the Virtual Journal of Nanoscale Science and Technology will gather "into one spot all the papers on a given topic that appear in a wide range of premier physics-related journals." The articles have been pre-selected by expert editors, so that specialists may turn to this convenient resource to stay on top of cutting-edge research. Access to articles will require a regular subscription to the specific journals, though non-subscribers do have the option of purchasing individual articles for immediate online delivery. Browsing the tables of contents and abstracts is free.

  3. Nanoscale conducting oxide PlasMOStor.

    PubMed

    Lee, Ho W; Papadakis, Georgia; Burgos, Stanley P; Chander, Krishnan; Kriesch, Arian; Pala, Ragip; Peschel, Ulf; Atwater, Harry A

    2014-11-12

    We experimentally demonstrate an ultracompact PlasMOStor, a plasmon slot waveguide field-effect modulator based on a transparent conducting oxide active region. By electrically modulating the conducting oxide material deposited into the gaps of highly confined plasmonic slot waveguides, we demonstrate field-effect dynamics giving rise to modulation with high dynamic range (2.71 dB/?m) and low waveguide loss (?0.45 dB/?m). The large modulation strength is due to the large change in complex dielectric function when the signal wavelength approaches the surface plasmon resonance in the voltage-tuned conducting oxide accumulation layer. The results provide insight about the design of ultracompact, nanoscale modulators for future integrated nanophotonic circuits. PMID:25302668

  4. Control of friction at the nanoscale

    DOEpatents

    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.

  5. Detecting nanoscale vibrations as signature of life.

    PubMed

    Kasas, Sandor; Ruggeri, Francesco Simone; Benadiba, Carine; Maillard, Caroline; Stupar, Petar; Tournu, Hélène; Dietler, Giovanni; Longo, Giovanni

    2015-01-13

    The existence of life in extreme conditions, in particular in extraterrestrial environments, is certainly one of the most intriguing scientific questions of our time. In this report, we demonstrate the use of an innovative nanoscale motion sensor in life-searching experiments in Earth-bound and interplanetary missions. This technique exploits the sensitivity of nanomechanical oscillators to transduce the small fluctuations that characterize living systems. The intensity of such movements is an indication of the viability of living specimens and conveys information related to their metabolic activity. Here, we show that the nanomotion detector can assess the viability of a vast range of biological specimens and that it could be the perfect complement to conventional chemical life-detection assays. Indeed, by combining chemical and dynamical measurements, we could achieve an unprecedented depth in the characterization of life in extreme and extraterrestrial environments. PMID:25548177

  6. Nanoscale characterization of engineered cementitious composites (ECC)

    SciTech Connect

    Sakulich, Aaron Richard, E-mail: asakulic@umich.edu; Li, Victor C.

    2011-02-15

    Engineered cementitious composites (ECC) are ultra-ductile fiber-reinforced cementitious composites. The nanoscale chemical and mechanical properties of three ECC formulae (one standard formula, and two containing nanomaterial additives) were studied using nanoindentation, electron microscopy, and energy dispersive spectroscopy. Nanoindentation results highlight the difference in modulus between bulk matrix ({approx} 30 GPa) and matrix/fiber interfacial transition zones as well as between matrix and unreacted fly ash ({approx} 20 GPa). The addition of carbon black or carbon nanotubes produced little variation in moduli when compared to standard M45-ECC. The indents were observed by electron microscopy; no trace of the carbon black particles could be found, but nanotubes, including nanotubes bridging cracks, were easily located in ultrafine cracks near PVA fibers. Elemental analysis failed to show a correlation between modulus and chemical composition, implying that factors such as porosity have more of an effect on mechanical properties than elemental composition.

  7. Probing absolute spin polarization at the nanoscale.

    PubMed

    Eltschka, Matthias; Jäck, Berthold; Assig, Maximilian; Kondrashov, Oleg V; Skvortsov, Mikhail A; Etzkorn, Markus; Ast, Christian R; Kern, Klaus

    2014-12-10

    Probing absolute values of spin polarization at the nanoscale offers insight into the fundamental mechanisms of spin-dependent transport. Employing the Zeeman splitting in superconducting tips (Meservey-Tedrow-Fulde effect), we introduce a novel spin-polarized scanning tunneling microscopy that combines the probing capability of the absolute values of spin polarization with precise control at the atomic scale. We utilize our novel approach to measure the locally resolved spin polarization of magnetic Co nanoislands on Cu(111). We find that the spin polarization is enhanced by 65% when increasing the width of the tunnel barrier by only 2.3 Å due to the different decay of the electron orbitals into vacuum. PMID:25423049

  8. Molecular bean studies of adsorption, desorption, and diffusion kinetics in nanoscale ice films

    SciTech Connect

    Smith, S.; Huang, C.; Stirniman, M.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    Heterogeneous gas/solid chemistry involving terrestrial ice particles and polar stratospheric clouds (PSCs) plays a critical role in determining the composition of the atmosphere. Unfortunately, a detailed predictive understanding of the elementary dynamical and kinetic process occurring on the surface of atmospheric particulates is presently unavailable. Molecular beam scattering and programmed desorption (both TPD, and isothermal) are used to study the adsorption, desorption, phase transition, and diffusion kinetics in nanoscale multilayer ice films. Sticking coefficients of H{sub 2}O, HCl, and NH{sub 3} are determined as a function of incident kinetic energy, angle and surface temperature. The branching between molecular and dissociative ({open_quotes}salvation{close_quotes}) chemisorption is probed by detecting isotopic exchange between the adsorbate and substrate. In related experiments, molecular beams of various reagents are used to create multicomponent thin films of varying composition and morphology with layer-by-layer atomic resolution. The experimental methods, results, and their relevance to heterogeneous environmental chemistry will be presented.

  9. Effect of ion structure on nanoscale friction in protic ionic liquids.

    PubMed

    Sweeney, James; Webber, Grant B; Rutland, Mark W; Atkin, Rob

    2014-08-21

    The effect of ionic liquid (IL) molecular structure on nanoscale friction has been investigated using colloidal probe Friction Force Microscopy (FFM). The ILs studied were ethylammonium formate (EAF), ethylammonium nitrate (EAN), propylammonium formate (PAF), propylammonium nitrate (PAN), dimethylethylammonium formate (DMEAF), and ethanolammonium nitrate (EtAN). ILs were confined between a silica colloid probe and a mica surface, and the friction force was measured as a function of normal load for sliding velocities between 10 and 40 ?m s(-1). At low normal forces, multiple IL layers are found between the probe and the surface, but at higher force, in the boundary layer regime, a single ion layer separates the probe and the surface. In the boundary layer regime energy is dissipated by two main pathways. Firstly, the ionic liquid near the surface, with the exception of the boundary layer, is expelled from the advancing contact made by the probe on the surface. This disruption in the interactions between the boundary layer and the near surface multilayers, leads to energy dissipation and depends on the strength of the attraction between the boundary and near surface layers. The second pathway is via rotations and twists of ions in the boundary layer, primarily associated with the cation terminal methyl group. The friction coefficient did not vary over the limited range of sliding speeds investigated. PMID:24992959

  10. Characterization Of Multi-layered Fish Scales (Atractosteus spatula) Using Nanoindentation, X-ray CT, FTIR, and SEM

    PubMed Central

    Allison, Paul G.; Rodriguez, Rogie I.; Moser, Robert D.; Williams, Brett A.; Poda, Aimee R.; Seiter, Jennifer M.; Lafferty, Brandon J.; Kennedy, Alan J.; Chandler, Mei Q.

    2014-01-01

    The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram’s horn, antlers, and turtle shells provides unique design principles with potentials for guiding the design of protective materials and systems in the future. Understanding the structure-property relationships for these material systems at the microscale and nanoscale where failure initiates is essential. Currently, experimental techniques such as nanoindentation, X-ray CT, and SEM provide researchers with a way to correlate the mechanical behavior with hierarchical microstructures of these material systems1-6. However, a well-defined standard procedure for specimen preparation of mineralized biomaterials is not currently available. In this study, the methods for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of A. spatula using nanoindentation, FTIR, SEM, with energy-dispersive X-ray (EDX) microanalysis, and X-ray CT are presented. PMID:25046233

  11. Design and development of multilayer vascular graft

    NASA Astrophysics Data System (ADS)

    Madhavan, Krishna

    2011-07-01

    Vascular graft is a widely-used medical device for the treatment of vascular diseases such as atherosclerosis and aneurysm as well as for the use of vascular access and pediatric shunt, which are major causes of mortality and morbidity in this world. Dysfunction of vascular grafts often occurs, particularly for grafts with diameter less than 6mm, and is associated with the design of graft materials. Mechanical strength, compliance, permeability, endothelialization and availability are issues of most concern for vascular graft materials. To address these issues, we have designed a biodegradable, compliant graft made of hybrid multilayer by combining an intimal equivalent, electrospun heparin-impregnated poly-epsilon-caprolactone nanofibers, with a medial equivalent, a crosslinked collagen-chitosan-based gel scaffold. The intimal equivalent is designed to build mechanical strength and stability suitable for in vivo grafting and to prevent thrombosis. The medial equivalent is designed to serve as a scaffold for the activity of the smooth muscle cells important for vascular healing and regeneration. Our results have shown that genipin is a biocompatible crosslinker to enhance the mechanical properties of collagen-chitosan based scaffolds, and the degradation time and the activity of smooth muscle cells in the scaffold can be modulated by the crosslinking degree. For vascular grafting and regeneration in vivo, an important design parameter of the hybrid multilayer is the interface adhesion between the intimal and medial equivalents. With diametrically opposite affinities to water, delamination of the two layers occurs. Physical or chemical modification techniques were thus used to enhance the adhesion. Microscopic examination and graft-relevant functional characterizations have been performed to evaluate these techniques. Results from characterization of microstructure and functional properties, including burst strength, compliance, water permeability and suture strength, showed that the multilayer graft possessed properties mimicking those of native vessels. Achieving these FDA-required functional properties is essential because they play critical roles in graft performances in vivo such as thrombus formation, occlusion, healing, and bleeding. In addition, cell studies and animal studies have been performed on the multilayer graft. Our results show that the multilayer graft support mimetic vascular culture of cells and the acellular graft serves as an artery equivalent in vivo to sustain the physiological conditions and promote appropriate cellular activity. In conclusion, the newly-developed hybrid multilayer graft provides a proper balance of biomechanical and biochemical properties and demonstrates the potential for the use of vascular tissue engineering and regeneration.

  12. Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

    PubMed

    Shen, Boxuan; Linko, Veikko; Dietz, Hendrik; Toppari, J Jussi

    2015-01-01

    DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached. PMID:25225147

  13. The experimental investigation of the effects of uncoated, PVD- and CVD-coated cemented carbide inserts and cutting parameters on surface roughness in CNC turning and its prediction using artificial neural networks

    Microsoft Academic Search

    Muammer Nalbant; Hasan Gökkaya; ?hsan Tokta?; Gökhan Sur

    2009-01-01

    In this study the machining of AISI 1030 steel (i.e. orthogonal cutting) uncoated, PVD- and CVD-coated cemented carbide insert with different feed rates of 0.25, 0.30, 0.35, 0.40 and 0.45mm\\/rev with the cutting speeds of 100, 200 and 300m\\/min by keeping depth of cuts constant (i.e. 2mm), without using cooling liquids has been accomplished. The surface roughness effects of coating

  14. Lead-free multilayer piezoelectric transformer

    NASA Astrophysics Data System (ADS)

    Guo, Mingsen; Jiang, X. P.; Lam, K. H.; Wang, S.; Sun, C. L.; Chan, Helen L. W.; Zhao, X. Z.

    2007-01-01

    In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3 ceramics is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, is 8.3mm long, 8.3mm wide, and 2.3mm thick. It operates in the second thickness extensional vibration mode. For a temperature rise of 20°C, the transformer has an output power of >0.3W. With a matching load resistance of 10?, its maximum efficiency approaches 81.5%, and the maximum voltage gain is 0.14. It has potential to be used in low voltage power supply units such as low power adapter and other electronic circuits.

  15. Multilayered (Hg,Cd)Te infrared detector

    NASA Technical Reports Server (NTRS)

    Rae, W. G.

    1977-01-01

    Multilayered mercury-cadmium telluride photoconductive detectors were developed which are capable of providing individual coverage of three separate spectral wavelength bands without the use of beam splitters. The multilayered "three-color" detector on a single dewar takes the place of three separate detector/filter/dewar units and enables simpler and more reliable mechanical and optical designs for multispectral scanners and radiometers. Wavelength channel design goals (in micrometers) were: 10.1 to 11.0, 11.0 to 12.0, and 13.0. Detectivity for all channels was 1 x 10 to the 10th power cm-Hz 1/2/Watt. A problem occurred in finding an epoxy layer which had good infrared transmission properties and which also was chemically and mechanically compatible with HgCdTe processing techniques. Data on 6 candidate bonding materials are surveyed and discussed.

  16. Solar absorption in thick and multilayered glazings

    SciTech Connect

    Powles, Rebecca; Curcija, Dragan; Kohler, Christian

    2002-02-01

    Thick and multilayered glazings generally have a nonuniform distribution of absorbed solar radiation which is not taken into account by current methods for calculating the center of glass solar gain and thermal performance of glazing systems. This paper presents a more accurate method for calculating the distribution of absorbed solar radiation inside thick and multilayered glazings and demonstrates that this can result in a small but significant difference in steady-state temperature profile and Solar Heat Gain Coefficient for some types of glazing systems when compared to the results of current methods. This indicates that a more detailed approach to calculating the distribution of absorbed solar radiation inside glazings and resulting thermal performance may be justified for certain applications.

  17. Magnetic properties of Ni/Tb multilayers

    NASA Astrophysics Data System (ADS)

    Schmidt, Thomas; Hoffmann, Horst

    2003-02-01

    Thin multilayer films of alternating ultrathin Ni and Tb layers ( tNi=5…80 Å, tTb=30 Å) were sputter-deposited at room temperature and magnetically characterised by temperature-dependent SQUID measurements and torque measurements at T=300 K. Despite of the multilayer structure of all samples and a transition of the microstructure of the Ni layers the measured spontaneous magnetic moment of all samples is explained by a band filling model in analogy to amorphous and crystalline NiRE alloys. The magnetic Ni moment is quenched by a successive filling of its 3d minority band by the 5d, 6 s conduction electrons of Tb. As long as the Ni moment is not zero an antiferromagnetic Ni-Tb coupling and a perpendicular anisotropy component appears. The corresponding results of structural investigations are given elsewhere J. Magn. Magn. Mater. 248 (2002) 181.

  18. The structure and dynamics of multilayer networks

    NASA Astrophysics Data System (ADS)

    Boccaletti, S.; Bianconi, G.; Criado, R.; del Genio, C. I.; Gómez-Gardeñes, J.; Romance, M.; Sendiña-Nadal, I.; Wang, Z.; Zanin, M.

    2014-11-01

    In the past years, network theory has successfully characterized the interaction among the constituents of a variety of complex systems, ranging from biological to technological, and social systems. However, up until recently, attention was almost exclusively given to networks in which all components were treated on equivalent footing, while neglecting all the extra information about the temporal- or context-related properties of the interactions under study. Only in the last years, taking advantage of the enhanced resolution in real data sets, network scientists have directed their interest to the multiplex character of real-world systems, and explicitly considered the time-varying and multilayer nature of networks. We offer here a comprehensive review on both structural and dynamical organization of graphs made of diverse relationships (layers) between its constituents, and cover several relevant issues, from a full redefinition of the basic structural measures, to understanding how the multilayer nature of the network affects processes and dynamics.

  19. The new ESRF multilayer deposition facility

    NASA Astrophysics Data System (ADS)

    Morawe, Ch.; Borel, Ch.; Peffen, J.-Ch.

    2007-09-01

    Recently, the ESRF Optics Group installed a new multilayer deposition facility. This upgrade was motivated by increasingly demanding requirements for multilayer based x-ray optics on modern 3rd generation synchrotron beamlines. Improved accuracy, stability, and reproducibility are key issues. The deposition process is based on non-reactive magnetron sputtering. The machine is equipped with four cathodes and one ion source for surface treatment. Conducting, insulating, and ferromagnetic materials can be deposited. A linear substrate motion will enable coatings up to 100 cm long and 15 cm wide. The talk will describe the basic concept of the machine and will give an overview of the operating conditions. Initial coating results will complement the presentation.

  20. Deconvolution of mixed magnetism in multilayer graphene

    SciTech Connect

    Swain, Akshaya Kumar [IITB-Monash Research Academy, Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076 (India); Bahadur, Dhirendra, E-mail: dhirenb@iitb.ac.in [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076 (India)

    2014-06-16

    Magnetic properties of graphite modified at the edges by KCl and exfoliated graphite in the form of twisted multilayered graphene (<4 layers) are analyzed to understand the evolution of magnetic behavior in the absence of any magnetic impurities. The mixed magnetism in multilayer graphene is deconvoluted using Low field-high field hysteresis loops at different temperatures. In addition to temperature and the applied magnetic field, the density of edge state spins and the interaction between them decides the nature of the magnetic state. By virtue of magnetometry and electron spin resonance studies, we demonstrate that ferromagnetism is intrinsic and is due to the interactions among various paramagnetic centers. The strength of these magnetic correlations can be controlled by modifying the structure.

  1. Multi-layer waste containment barrier

    DOEpatents

    Smith, Ann Marie (Pocatello, ID); Gardner, Bradley M. (Idaho Falls, ID); Nickelson, David F. (Idaho Falls, ID)

    1999-01-01

    An apparatus for constructing an underground containment barrier for containing an in-situ portion of earth. The apparatus includes an excavating device for simultaneously (i) excavating earthen material from beside the in-situ portion of earth without removing the in-situ portion and thereby forming an open side trench defined by opposing earthen sidewalls, and (ii) excavating earthen material from beneath the in-situ portion of earth without removing the in-situ portion and thereby forming a generally horizontal underground trench beneath the in-situ portion defined by opposing earthen sidewalls. The apparatus further includes a barrier-forming device attached to the excavating device for simultaneously forming a side barrier within the open trench and a generally horizontal, multi-layer barrier within the generally horizontal trench. The multi-layer barrier includes at least a first layer and a second layer.

  2. Trapping and Manipulation of Isolated Atoms Using Nanoscale Plasmonic Structures

    E-print Network

    Chang, D. E.

    We propose and analyze a scheme to interface individual neutral atoms with nanoscale solid-state systems. The interface is enabled by optically trapping the atom via the strong near-field generated by a sharp metallic ...

  3. Design and implementation of nanoscale fiber mechanical testing apparatus

    E-print Network

    Brayanov, Jordan, 1981-

    2004-01-01

    The rapid growth in the synthetic manufacturing industry demands higher resolution mechanical testing devices, capable of working with nanoscale fibers. A new device has been developed to perform single-axis tensile tests ...

  4. Electronic structure and transport in molecular and nanoscale electronics

    E-print Network

    Qian, Xiaofeng

    2008-01-01

    Two approaches based on first-principles method are developed to qualitatively and quantitatively study electronic structure and phase-coherent transport in molecular and nanoscale electronics, where both quantum mechanical ...

  5. Nanoscale structure and transport : from atoms to devices

    E-print Network

    Evans, Matthew Hiram

    2005-01-01

    Nanoscale structures present both unique physics and unique theoretical challenges. Atomic-scale simulations can find novel nanostructures with desirable properties, but the search can be difficult if the wide range of ...

  6. Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films

    E-print Network

    Kim, Bo Hung

    2010-07-14

    Molecular Dynamics (MD) simulations of nano-scale flows typically utilize fixed lattice crystal interactions between the fluid and stationary wall molecules. This approach cannot properly model thermal interactions at the wall-fluid interface...

  7. Negative pressure characteristics of an evaporating meniscus at nanoscale

    E-print Network

    Maroo, Shalabh C.

    2011-01-01

    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 ...

  8. Bioremediation of Uranium Plumes with Nano-scale

    E-print Network

    Fay, Noah

    Bioremediation of Uranium Plumes with Nano-scale Zero-valent Iron Angela Athey Advisers: Dr. Reyes and economically feasible e-donor for uranium bioremediation 15 #12;Future Work · Determine uranium solubility

  9. Stable Storage of Helium in Nanoscale Platelets at Semicoherent Interfaces

    E-print Network

    Kashinath, Abishek

    He implanted into metals precipitates into nanoscale bubbles that may later grow into voids, degrading the properties of engineering alloys. Using multiscale modeling, we show that a different class of He precipitates may ...

  10. Science and Technology at the Nanoscale Materials Science & Engineering

    E-print Network

    Prinz, Friedrich B.

    Nanocrystal and Nanowire Synthesis, Characterization and Devices Professor William Chueh Electrochemistry Jennifer Dionne Lights, Chemistry, Action! Light-induced synthesis of novel catalysts for energy Professor Sarah Heilshorn Design of Biomaterials with Nanoscale Precision through Protein Engineering Professor

  11. Nanoscale magnetic sensing using spin qubits in diamond

    E-print Network

    Maze, J. R.

    The ability to sense nanotelsa magnetic fields with nanoscale spatial resolution is an outstanding technical challenge relevant to the physical and biological sciences. For example, detection of such weak localized fields ...

  12. Nanoscale strength distribution in amorphous versus crystalline metals

    E-print Network

    Packard, C.E.

    Low-load nanoindentation can be used to assess not only the plastic yield point, but the distribution of yield points in a material. This paper reviews measurements of the so-called nanoscale strength distribution (NSD) ...

  13. Perspectives Nanotechnology and the public: Effectively communicating nanoscale science

    E-print Network

    Crone, Wendy C.

    Perspectives Nanotechnology and the public: Effectively communicating nanoscale science August 2006 Key words: nanotechnology, communication, public knowledge, public understanding the public on concepts and applications associated with nanotechnology. The goal of our work

  14. Electrical and Optical Characterization of Nanoscale Materials for Electronics

    E-print Network

    Chang, Chi-Yuan 1980-

    2012-10-05

    resonance in nanoscale silver enhancing probes made by thermal silver evaporation on sharp AFM tips. As the system was designed along an off-axis illumination/collection scheme, it was demonstrated that it was capable of observing molecular decomposition...

  15. Packaging of MMICs in multilayer LCP substrates

    Microsoft Academic Search

    Dane C. Thompson; Manos M. Tentzeris; John Papapolymerou

    2006-01-01

    A 13-25-GHz GaAs bare die low noise amplifier is embedded inside a multilayer liquid crystal polymer (LCP) package made from seven layers of thin-film LCP. This new packaging topology has inherently unique properties that could make it an attractive alternative in some instances to traditional metal and ceramic hermetic packages. LCP is a near-hermetic material and its lamination process is

  16. Response time for multilayered platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.; Ash, R. L.

    1985-01-01

    Response time constants for several multilayered temperature transducers were determined numerically by using Martin Marietta's MITAS software package which is available at NASA Langley Research Center. Present results were found in close agreement with the solutions reported in the literature, thus, the capability of MITAS was justified. On the basis of experiences gained, the MITAS is recommended for use in predicting the response time constants of sensors by an in-situ technique.

  17. Neutron Buildup Factors for Multilayered-Media

    Microsoft Academic Search

    M. Abou Mandour; M. Hassan

    1987-01-01

    The buildup factors for high energy neutrons of 14.1 MeV in a two-layered medium are calculated using the Monte Carlo method. Neutrons from planar monodirectional source are assumed to be incident on the surface of the multilayered-medium. A systematic study is carried out for the two cases: carbon-iron medium and iron-carbon medium. The value of the buildup factor is strongly

  18. Adsorption of ammonia on multilayer iron phthalocyanine

    SciTech Connect

    Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim [Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund (Sweden); Schulte, Karina [MAX-lab, Lund University, Box 118, 221 00 Lund (Sweden); Wang Bin; Bocquet, Marie-Laure [Laboratoire de chimie, Ecole normale superieure de Lyon, 46, Allee d'Italie, 69364 Lyon Cedex 07 (France)

    2011-03-21

    The adsorption of ammonia on multilayers of well-ordered, flat-lying iron phthalocyanine (FePc) molecules on a Au(111) support was investigated by x-ray photoelectron spectroscopy. We find that the electron-donating ammonia molecules coordinate to the metal centers of iron phthlalocyanine. The coordination of ammonia induces changes of the electronic structure of the iron phthalocyanine layer, which, in particular, lead to a modification of the FePc valence electron spin.

  19. Interface Structure in Metal/carbon Multilayers

    NASA Astrophysics Data System (ADS)

    Chan, Yuet-Loy

    A series of ultra thin Metal/Carbon (W/C, Ti/C and Si/C) multilayers was studied by using a diverse number of techniques (RBS, AS, EELS, AREELS, SEELFS, and X-ray Reflectivity at Small Angles). The samples were prepared by conventional techniques. The substrates used for the samples preparation are Si (111), alpha -Al_2O_3, and SiO_2. The thickness of the bilayer in each of the multilayers is in the order of Armstrong. Single crystals (TiC, SiC) were also studied for the purpose of supplying the reference points for the identification of the behavior of these metallic multilayers, especially the electronic excitations. Some samples were measured as a function of temperature by using EELS under UHV conditions. We observed the formation of a carbide at the W/C interface. The structure of the interface was identified using surface electron energy loss fine structure and X -ray diffraction. We observed that the Ti/C interface is isolated by a thin titanium oxide layer. The electron density of carbon shows a graphitic character. We found that the interface has a graphite like atomic arrangement rather than a carbide like arrangement. Angular resolved electron energy loss measurements show that a carbidic interface is present at the silicon -carbon interface. The structure of silicon/carbon multilayers has also been studied by using x-ray reflectivity. We found from the analysis of the data that a carbidic interface forms at the silicon-carbon interface for samples heated in vacuum to 873 K.

  20. Magnetoresistance of magnetic multilayers: understanding Ohm's law

    Microsoft Academic Search

    Smadar Shatz; Nathan Wiser

    2001-01-01

    The magnetic-field dependence of the magnetoresistance MR(H) of magnetic multilayers in the CPP mode (current perpendicular to the layers) was recently measured for two samples that differ only in the ordering of the layers: [Fe\\/Cu\\/Co\\/Cu]N and [Fe\\/Cu]N[Co\\/Cu]N, where N denotes the number of repeats. Ohm's law states that MR(H) should be the same for these two samples because in a

  1. Multilayer Nanofilms as Substrates for Hepatocellular Applications

    PubMed Central

    Wittmer, Corinne R.; Phelps, Jennifer A.; Lepus, Christin M.; Saltzman, W. Mark; Harding, Martha J.; Van Tassel, Paul R.

    2008-01-01

    Multilayer nanofilms, formed by the layer-by-layer (LbL) adsorption of positively and negatively charged polyelectrolytes, are promising substrates for tissue engineering. We investigate here the attachmemt and function of hepatic cells on multilayer films in terms of film composition, terminal layer, rigidity, charge, and presence of biofunctional species. Human hepatocellular carcinoma cells (HepG2), adult rat hepatocytes (ARH), and human fetal hepatoblasts (HFHb) are studied on films composed of the polysaccharides chitosan (CHI) and alginate (ALG), the polypeptides poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA), and the synthetic polymers poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS). The influence of chemical cross-linking following LbL assembly is also investigated. We find HepG2 to reach confluence after seven days of culture on only 2 of 18 candidate multilayer systems: (PAH-PSS)n (i.e. n PAH-PSS bilayers) and cross-linked (PLL-ALG)n-PLL. These two systems, as well as cross-linked (PLL-PGA)n-PLL, support attachment and function (in terms of albumin production) of ARH, provided collagen is adsorbed to the top of the film. (PAH-PSS)n, cross-linked (PLL-ALG)n, and cross-linked (PLL-PGA)n-PLL films all support attachment, layer confluence, and function of HFHb, with the latter film promoting the greatest level of function at 8 days. Overall, film composition, terminal layer, and rigidity are key variables in promoting attachment and function of hepatic cells, while film charge and biofunctionality are somewhat less important. These studies reveal optimal candidate multilayer biomaterials for human liver tissue engineering applications. PMID:18653230

  2. Equilibrium and diffusion in coherent multilayers

    SciTech Connect

    Purdy, G.R. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering] [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering; Brechet, Y.J.M. [Inst. National Polytechnique de Grenoble, Saint Martin d`Heres (France)] [Inst. National Polytechnique de Grenoble, Saint Martin d`Heres (France)

    1996-12-01

    A thermodynamic treatment is presented of isothermal phase equilibria and diffusion in coherent planar multilayers. For two-component systems, coherent two-phase equilibrium compositions can often be generated using the familiar procedure in which a line is constructed doubly tangential to the coherent free energy functional(s). Only in special cases, however, are the phase equilibria so generated independent of the average composition (for unsupported multilayers) or the substrate effective composition (for multilayers coherently attached to a substrate). The common tangent construction is extended to ternary solution systems, and conditions for which the coherent ternary equilibria are independent of the average or substrate compositions defined. The formal thermodynamic aspects of diffusion in binary and ternary solids are reviewed, and the expected effects of coherency strain on the diffusional homogenization process outlined. The diffusion formalism can often be extended to account for coherency strains simply by substituting the coherent free energy density for its incoherent counterpart. In ternary and higher order systems, it is always possible to choose an initial condition that is free of strain; it is not in general possible to maintain this strain-free condition during the course of diffusional homogenization. The general effect of strain energy on ternary diffusion is to rotate the diffusion eigenvectors such that the strain is reduced. Some sample calculations are presented for the system Cu-Au-Ag.

  3. Automation Enhancement of Multilayer Laue Lenses

    SciTech Connect

    Lauer K. R.; Conley R.

    2010-12-01

    X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

  4. Ultrasonic wave propagation in multilayered piezoelectric substrates

    SciTech Connect

    Chien, H.T.; Sheen, S.H.; Raptis, A.C.

    1994-04-11

    Due to the increasing demand for higher operating frequency, lower attenuation, and stronger piezoelectricity, use of the layered structure has become necessary. Theoretical studies are carried out for ultrasonic waves propagating in the multilayered piezoelectric substrates. Each layer processes up to as low as monoclinic symmetry with various thickness and orientation. A plane acoustic wave is assumed to be incident, at varied frequency and incidence angle, from a fluid upon a multilayered substrate. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the multilayered piezoelectric substrates. Solutions are obtained for the individual layers which relate the field variables at the upper layer surfaces. The response of the total system proceeds by satisfying appropriate interfacial conditions across the layers. Based on the boundary conditions, two cases, {open_quotes}shorted{close_quotes} and {open_quotes}free{close_quotes}, are derived from which a so-called piezoelectric coupling factor is calculated to show the piezoelectric efficiency. Our results are rather general and show that the phase velocity is a function of frequency, layer thickness, and orientation.

  5. Young's modulus of polyelectrolyte multilayers from microcapsule swelling

    E-print Network

    O. I. Vinogradova; D. Andrienko; V. V. Lulevich; S. Nordschild; G. B. Sukhorukov

    2003-07-24

    We measure Young's modulus of a free polyelectrolyte multilayer film by studying osmotically induced swelling of polyelectrolyte multilayer microcapsules filled with the polyelectrolyte solution. Different filling techniques and core templates were used for the capsule preparation. Varying the concentration of the polyelectrolyte inside the capsule, its radius and the shell thickness yielded an estimate of an upper limit for Young's modulus of the order of 100 MPa. This corresponds to an elastomer and reflects strong interactions between polyanions and polycations in the multilayer.

  6. A method to construct polyelectrolyte multilayers film containing gold nanoparticles

    Microsoft Academic Search

    Hongjun Chen; Shaojun Dong

    2007-01-01

    Gold nanoparticles in polyelectrolyte multilayers film can be easily prepared by repeating immersion of a substrate in poly(diallyl dimethylammonium) chloride (PDDA)-AuCl4? complexes solution followed by reduction Au3+ through heating. UV–vis spectroscopy, cyclic voltammetry (CV) and tapping-mode atomic force microscopy (AFM) are used to confirm the successful construction of the polyelectrolyte multilayers film and the formation of gold nanoparticles. The multilayers

  7. Nanomechanical properties of polyaniline and azo polyelectrolyte multilayer films

    Microsoft Academic Search

    Hao-yu Zhang; Xin-yang Li; Xiao-gong Wang

    2010-01-01

    Nanomechanical properties of multilayer films constructed of polyaniline (PANI) and azobeneze-containing polyelectrolytes\\u000a (PNACN and PPAPE) were studied by using nanoindentation method. The multilayer films were prepared by the electrostatic layer-by-layer\\u000a self-assembly through alternately dipping in the polymer solutions. The multilayer films deposited onto the glass slides after\\u000a proper dry were used for the nanomechanical property testing. The nanomechanical measurement indicated

  8. Amperometric uric acid sensors based on polyelectrolyte multilayer films

    Microsoft Academic Search

    Tomonori Hoshi; Hidekazu Saiki; Jun-ichi Anzai

    2003-01-01

    Uricase (UOx) and polyelectrolyte were used for preparation of a permselective multilayer film and enzyme multilayer films on a platinum (Pt) electrode, allowing the detection of uric acid amperometrically. The polyelectrolyte multilayer (PEM) film composed of poly(allylamine) (PAA) and poly(vinyl sulfate) (PVS) were prepared via layer-by-layer assembly on the electrode, functioning as H2O2-selective film. After deposition of the permselective film

  9. SELECTIVE ADSORPTION OF AMPHIPHILIC BLOCK COPOLYMERS ON WEAK POLYELECTROLYTE MULTILAYERS

    Microsoft Academic Search

    Jeeyoung Choi; M. F. Rubner

    2001-01-01

    In this study, an amphiphilic block copolymer, polystyrene-block-poly(acrylic acid) (PS-PAA), was adsorbed from tetrahydrofuran (THF) solution onto self-assembled weak polyelectrolyte multilayer surfaces of poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). The short hydrophilic PAA block adsorbs to the multilayer surface as an anchor block and the long hydrophobic PS block then dangles out from the surface. Several different PAA\\/PAH multilayer

  10. Surface-Phonon Polariton Contribution to Nanoscale Radiative Heat Transfer

    Microsoft Academic Search

    Emmanuel Rousseau; Marine Laroche; Jean-Jacques Greet

    Heat transfer between two plates of polar materials at nanoscale distance is known to be enhanced by several orders of magnitude as compared with its far-field value. In this article, we show that nanoscale heat transfer is dominated by the coupling between surface phonon-polaritons located on each interface. Furthermore, we derive an asymptotic closed-form expression of the radiative heat transfer

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

    Microsoft Academic Search

    Shiao-Shing Chen; Hong-Der Hsu; Chi-Wang Li

    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 25.4m2\\/g. The

  12. A numerical study of ballistic transport in a nanoscale MOSFET

    Microsoft Academic Search

    Jung-Hoon Rhew; Zhibin Ren; Mark S. Lundstrom

    2002-01-01

    We examine the physics of ballistic transport in a nanoscale MOSFET as reflected in the shape of the distribution function. We calculate the electron distribution function in the ballistic limit by solving the 1D steady-state Boltzmann transport equation self-consistently with the 2D Poisson equation in an n-channel ultra-thin-body nanoscale double-gate SOI MOSFET. In equilibrium, symmetry of the distribution function is

  13. 76 FR 19034 - Multilayered Wood Flooring From the People's Republic of China: Preliminary Affirmative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-06

    ...C-570-971] Multilayered Wood Flooring From the People's...and exporters of multilayered wood flooring from the People's...Jordan, Patricia Tran, or Joshua Morris, AD/CVD Operations...Register. See Multilayered Wood Flooring from the...

  14. 76 FR 92 - Multilayered Wood Flooring From the People's Republic of China: Postponement of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-03

    ...C-570-971] Multilayered Wood Flooring From the People's...CONTACT: Seth Isenberg and Joshua Morris, AD/ CVD Operations...investigation of multilayered wood flooring from the People's...PRC''). See Multilayered Wood Flooring From the...

  15. 76 FR 76693 - Multilayered Wood Flooring From the People's Republic of China: Countervailing Duty Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-08

    ...C-570-971] Multilayered Wood Flooring From the People's...order on multilayered wood flooring from the People's...FURTHER INFORMATION CONTACT: Joshua Morris, AD/CVD Operations...and exporters of multilayered wood flooring from the PRC....

  16. Structural and Mechanical Properties of Polyelectrolyte Multilayer Films Studied by AFM

    E-print Network

    Barrett, Christopher

    Structural and Mechanical Properties of Polyelectrolyte Multilayer Films Studied by AFM Ozzy Mermut Received September 18, 2003 ABSTRACT: Mechanical properties of polyelectrolyte multilayer thin films were, prepared to have identical thickness. Multilayer films assembled with polyelectrolytes of high charge

  17. The development, characterization, and application of biomimetic nanoscale enzyme immobilization

    NASA Astrophysics Data System (ADS)

    Haase, Nicholas R.

    The utilization of enzymes is of interest for applications such as biosensors and biofuel cells. Immobilizing enzymes provides a means to develop these applications. Previous immobilization efforts have been accomplished by exposing surfaces on which silica-forming molecules are present to solutions containing an enzyme and a silica precursor. This approach leads to the enzyme being entrapped in a matrix three orders of magnitude larger than the enzyme itself, resulting in low retention of enzyme activity. The research herein introduces a method for the immobilization of enzymes during the layer-by-layer buildup of Si-O and Ti-O coatings which are nanoscale in thickness. This approach is an application of a peptide-induced mineral deposition method developed in the Sandhage and Kroger groups, and it involves the alternating exposure of a surface to solutions containing the peptide protamine and then an aqueous precursor solution of silicon- or titanium-oxide at near-neutral pH. A method has been developed that enables in situ immobilization of enzymes in the protamine/mineral oxide coatings. Depending on the layer and mineral (silica or titania) within which the enzyme is incorporated, the resulting multilayer biocatalytic hybrid materials retain 20 -- 100% of the enzyme activity. Analyses of kinetic properties of the immobilized enzyme, coupled with characterization of physical properties of the mineral-bearing layers (thickness, porosity, pore size distribution), indicates that the catalytic activities of the enzymes immobilized in the different layers are largely determined by substrate diffusion. The enzyme was also found to be substantially stabilized against heat-induced denaturation and largely protected from proteolytic attack. These functional coatings are then developed for use as antimicrobial materials. Glucose oxidase, which catalyzes production of the cytotoxic agent hydrogen peroxide, was immobilized with silver nanoparticles, can release antimicrobial silver ions. It is demonstrated that these two antimicrobial agents work in a synergistic manner for enhanced antimicrobial efficacy. Evidence of the proposed mechanism of synergy, namely enhanced release of silver ions by reaction of H2O2 with silver nanoparticles, is provided. Finally, the deployment of these materials in silk fibroins for development as wound dressings is also presented. Protamine cross-linking was then extended to the oxygen-reducing enzyme laccase to explore the use of this modified enzyme in an enzymatic biocathode. In this application laccase accepts electrons from the electrode and uses them to reduce oxygen to water molecules. The protamine-cross-linked enzyme exhibits a higher degree of immobilization, better retention of activity once immobilized, and superior electrochemical activity versus the native enzyme. Finally, preliminary research on the structure-function relationships of 16-mer peptides which adsorb to surfaces and deposit titanium oxide is presented. Specifically, the effect of content and distribution of arginine residues on the ability of peptides to adsorb to surfaces and subsequently deposit mineral oxides was investigated. The data demonstrate that surface adsorption of the peptides relies on both a critical number of arginine residues and their position within the peptide. Furthermore, the exchange of serine against arginine residues in surface-adsorbed peptides is detrimental to Ti-O deposition.

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

    PubMed Central

    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

  19. Modeling, identification, and application of multilayer polypyrrole conducting polymer actuators

    E-print Network

    Secord, Thomas W. (Thomas William)

    2007-01-01

    Experiments were performed using commercially available, self-contained, multilayer polypyrrole (PPy) actuators to develop low-order lumped parameter models of actuator electrical, mechanical, and electromechanical behavior. ...

  20. Interface controlled amorphization of crystalline Ni/Ti multilayers

    SciTech Connect

    Jankowski, A. F.; Hayes, J. P.; Ramsey, P. B.

    1993-12-01

    Solid-State Amorphization (SSA) of crystalline interfaces is observed in the Ni/Ti multilayer system. The amorphization reaction nucleates at location(s) of crystallographic disorder, i.e. the multilayer interfaces. Microstructural analyses reveal the sputter-deposited growth structure to be epitaxial with semi-coherent interfaces. Strain energy originating from interface lattice distortions varies as a function of the multilayer repeat spacing. Therefore, the interfacial energy effects the onset conditions for SSA. Differential thermal analysis is used to measure the critical temperature T{sub c}, to the nucleation of the SSA, which is found to vary with the Ni/Ti multilayer pair spacing.

  1. Effect of RGD-functionalization and stiffness modulation of polyelectrolyte multilayer films on muscle cell differentiation

    PubMed Central

    Gribova, Varvara; Gauthier-Rouvière, Cécile; Albigès-Rizo, Corinne; Auzely-Velty, Rachel; Picart, Catherine

    2014-01-01

    Skeletal muscle tissue engineering holds promise for the replacement of muscle due to an injury and for the treatment of muscle diseases. Although RGD substrates have been widely explored in tissue engineering, there is no study aimed at investigating the combined effects of RGD nanoscale presentation and matrix stiffness on myogenesis. In the present work, we use polyelectrolyte multilayer films made of poly(L-lysine) (PLL) and poly(L-glutamic) acid (PGA) as substrates of tunable stiffness that can be functionalized by a RGD adhesive peptide to investigate important events in myogenesis, including adhesion, migration, proliferation and differentiation. C2C12 myoblasts were used as cellular models. RGD presentation on soft films and increased film stiffness could both induce cell adhesion, but integrins involved in adhesion were different in case of soft and stiff films. Moreover, soft films with RGD peptide appeared to be the most appropriate substrate for myogenic differentiation while the stiff PLL/PGA films significantly induced cell migration, proliferation and inhibited myogenic differentiation. The ROCK kinase was found to be involved in myoblast response to the different films. Indeed, its inhibition was sufficient to rescue the differentiation on stiff films, but no significant changes were observed on stiff films with the RGD peptide. These results suggest that different signaling pathways may be activated depending on mechanical and biochemical properties of the multilayer films. This study emphasizes the superior advantage of the soft PLL/PGA films presenting the RGD peptide in terms of myogenic differentiation. This soft RGD-presenting film may be further used as coating of various polymeric scaffolds for muscle tissue engineering. PMID:23261924

  2. Effect of RGD functionalization and stiffness modulation of polyelectrolyte multilayer films on muscle cell differentiation.

    PubMed

    Gribova, Varvara; Gauthier-Rouvière, Cécile; Albigès-Rizo, Corinne; Auzely-Velty, Rachel; Picart, Catherine

    2013-05-01

    Skeletal muscle tissue engineering holds promise for the replacement of muscle damaged by injury and for the treatment of muscle diseases. Although arginylglycylaspartic acid (RGD) substrates have been widely explored in tissue engineering, there have been no studies aimed at investigating the combined effects of RGD nanoscale presentation and matrix stiffness on myogenesis. In the present work we use polyelectrolyte multilayer films made of poly(L-lysine) (PLL) and poly(L-glutamic) acid (PGA) as substrates of tunable stiffness that can be functionalized by a RGD adhesive peptide to investigate important events in myogenesis, including adhesion, migration, proliferation and differentiation. C2C12 myoblasts were used as cellular models. RGD presentation on soft films and increasing film stiffness could both induce cell adhesion, but the integrins involved in adhesion were different in the case of soft and stiff films. Soft films with RGD peptide appeared to be the most appropriate substrate for myogenic differentiation, while the stiff PLL/PGA films induced significant cell migration and proliferation and inhibited myogenic differentiation. ROCK kinase was found to be involved in the myoblast response to the different films. Indeed, its inhibition was sufficient to rescue differentiation on stiff films, but no significant changes were observed on stiff films with the RGD peptide. These results suggest that different signaling pathways may be activated depending on the mechanical and biochemical properties of multilayer films. This study emphasizes the advantage of soft PLL/PGA films presenting the RGD peptide in terms of myogenic differentiation. This soft RGD-presenting film may be further used as a coating of various polymeric scaffolds for muscle tissue engineering. PMID:23261924

  3. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    SciTech Connect

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and processing techniques for these coatings. In addition, we investigated the effect of microstructure on the mechanical properties and oxidation protection ability of the coatings. Coatings were developed to provide oxidation protection to both ferritic and austentic alloys and Ni-based alloys. The coatings that we developed are based on low viscosity pre-ceramic polymers. Thus they can be easily applied to any shape by using a variety of techniques including dip-coating, spray-coating and painting. The polymers are loaded with a variety of nanoparticles. The nanoparticles have two primary roles: control of the final composition and phases (and hence the properties); and control of the shrinkage during thermal decomposition of the polymer. Thus the selection of the nanoparticles was the most critical aspect of this project. Based on the results of the processing studies, the performance of selected coatings in oxidizing conditions (both static and cyclic) was investigated.

  4. Self-propagating reactions in Al/Zr multilayers: Anomalous dependence of reaction velocity on bilayer thickness

    SciTech Connect

    Barron, S. C.; Kelly, S. T.; Kirchhoff, J.; Knepper, R.; Fisher, K.; Hufnagel, T. C.; Weihs, T. P. [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Livi, K. J. T. [Department of Earth and Planetary Sciences, Integrated Imaging Center, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Earth and Planetary Sciences, Integrated Imaging Center, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Dufresne, E. M.; Fezzaa, K. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Barbee, T. W. [Condensed Matter and Materials Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Condensed Matter and Materials Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2013-12-14

    High temperature, self-propagating reactions are observed in vapor-deposited Al/Zr multilayered foils of overall atomic ratios 3 Al:1 Zr and 2 Al:1 Zr and nanoscale layer thicknesses; however, the reaction velocities do not exhibit the inverse dependence on bilayer thickness that is expected based on changes in the average diffusion distance. Instead, for bilayer thicknesses of 20-30 nm, the velocity is essentially constant at ?7.7 m/s. We explore several possible explanations for this anomalous behavior, including microstructural factors, changes in the phase evolution, and phase transformations in the reactant layers, but find no conclusive explanations. We determine that the phase evolution during self-propagating reactions in foils with a 3 Al:1 Zr stoichiometry is a rapid transformation from Al/Zr multilayers to the equilibrium intermetallic Al{sub 3}Zr compound with no intermediate crystalline phases. This phase evolution is the same for foils of 90 nm bilayer thicknesses and foils of bilayer thicknesses in the range of 27 nm to 35 nm. Further, for foils with a bilayer thickness of 90 nm and a 3 Al:1 Zr overall chemistry, the propagation front is planar and steady, in contrast to unsteady reaction fronts in foils with 1 Al:1 Zr overall chemistry and similar bilayer thicknesses.

  5. Self-propagating reactions in Al/Zr multilayers: Anomalous dependence of reaction velocity on bilayer thickness

    NASA Astrophysics Data System (ADS)

    Barron, S. C.; Kelly, S. T.; Kirchhoff, J.; Knepper, R.; Fisher, K.; Livi, K. J. T.; Dufresne, E. M.; Fezzaa, K.; Barbee, T. W.; Hufnagel, T. C.; Weihs, T. P.

    2013-12-01

    High temperature, self-propagating reactions are observed in vapor-deposited Al/Zr multilayered foils of overall atomic ratios 3 Al:1 Zr and 2 Al:1 Zr and nanoscale layer thicknesses; however, the reaction velocities do not exhibit the inverse dependence on bilayer thickness that is expected based on changes in the average diffusion distance. Instead, for bilayer thicknesses of 20-30 nm, the velocity is essentially constant at ˜7.7 m/s. We explore several possible explanations for this anomalous behavior, including microstructural factors, changes in the phase evolution, and phase transformations in the reactant layers, but find no conclusive explanations. We determine that the phase evolution during self-propagating reactions in foils with a 3 Al:1 Zr stoichiometry is a rapid transformation from Al/Zr multilayers to the equilibrium intermetallic Al3Zr compound with no intermediate crystalline phases. This phase evolution is the same for foils of 90 nm bilayer thicknesses and foils of bilayer thicknesses in the range of 27 nm to 35 nm. Further, for foils with a bilayer thickness of 90 nm and a 3 Al:1 Zr overall chemistry, the propagation front is planar and steady, in contrast to unsteady reaction fronts in foils with 1 Al:1 Zr overall chemistry and similar bilayer thicknesses.

  6. Sulfidation of cadmium at the nanoscale.

    PubMed

    Cabot, Andreu; Smith, Rachel K; Yin, Yadong; Zheng, Haimei; Reinhard, Björn M; Liu, Haitao; Alivisatos, A Paul

    2008-07-01

    We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that this system differs significantly from others in which the nanoscale Kirkendall effect has been used to create hollow particles. In previously reported systems, partial reaction creates a hollow particle with a spherically symmetric metal core connected to the outer shell by filaments. In contrast, here we obtain a lower symmetry structure, in which the unreacted metal core and the coalesced vacancies separate into two distinct spherical caps, minimizing the metal/void interface. This pattern of void coalescence is likely to occur in situations where the metal/vacancy self-diffusivities in the core are greater than the diffusivity of the cations through the shell. PMID:19206314

  7. Sulfidation of Cadmium at the Nanoscale

    SciTech Connect

    Cabot, Andreu; Smith, Rachel; Yin, Yadong; Zheng, Haimei; Reinhard, Bjorn; Liu, Haitao; Alivisatos, A. Paul

    2008-05-22

    We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that this system differs significantly from others in which the nanoscale Kirkendall effect has been used to create hollow particles. In previously reported systems, partial reaction creates a hollow particle with a spherically symmetric metal core connected to the outer shell by filaments. In contrast, here we obtain a lower symmetry structure, in which the unreacted metal core and the coalesced vacancies separate into two distinct spherical caps, minimizing the metal/void interface. This pattern of void coalescence is likely to occur in situations where the metal/vacancy self-diffusivities in the core are greater than the diffusivity of the cations through the shell.

  8. On nanoscale metallic iron for groundwater remediation.

    PubMed

    Noubactep, C; Caré, S

    2010-10-15

    This communication challenges the concept that nanoscale metallic iron (nano-Fe(0)) is a strong reducing agents for contaminant reductive transformation. It is shown that the inherent relationship between contaminant removal and Fe(0) oxidative dissolution which is conventionally attributed to contaminant reduction by nano-Fe(0) (direct reduction) could equally be attributed to contaminant removal by adsorption and co-precipitation. For reducible contaminants, indirect reduction by adsorbed Fe(II) or adsorbed H produced by corroding iron (indirect reduction) is even a more probable reaction path. As a result, the contaminant removal efficiency is strongly dependent on the extent of iron corrosion which is larger for nano-Fe(0) than for micro-Fe(0) in the short term. However, because of the increased reactivity, nano-Fe(0) will deplete in the short term. No more source of reducing agents (Fe(II), H and H(2)) will be available in the system. Therefore, the efficiency of nano-Fe(0) as a reducing agent for environmental remediation is yet to be demonstrated. PMID:20594643

  9. Non-Equilibrium Nanoscale Self-Organization

    SciTech Connect

    Aziz, Michael J

    2006-03-09

    Self-organized one- and two-dimensional arrays of nanoscale surface features ("ripples" and "dots") sometimes form spontaneously on initially flat surfaces eroded by a directed ion beam in a process called "sputter patterning". Experiments on this sputter patterning process with focused and unfocused ion beams, combined with theoretical advances, have been responsible for a number of scientific advances. Particularly noteworthy are (i) the discovery of propagative, rather than dissipative, behavior under some ion erosion conditions, permitting a pattern to be fabricated at a large length scale and propagated over large distances while maintaining, or even sharpening, the sharpest features; (ii) the first demonstration of guided self-organization of sputter patterns, along with the observation that defect density is minimized when the spacing between boundaries is near an integer times the natural spatial period; and (iii) the discovery of metastability of smooth surfaces, which contradicts the nearly universally accepted linear stability theory that predicts that any surface is linearly unstable to sinusoidal perturbations of some wave vector.

  10. Nanoscale magnetic biotransport with application to magnetofection

    NASA Astrophysics Data System (ADS)

    Furlani, E. P.; Ng, K. C.

    2008-06-01

    We present a model for predicting the transport of biofunctional magnetic nanoparticles in a passive magnetophoretic system that consists of a fluidic chamber positioned above a rare-earth magnet. The model is based on a drift-diffusion equation that governs the particle concentration in the chamber. We solve this equation numerically using the finite volume method. We apply the model to the magnetofection process wherein the magnetic force produced by the magnet attracts magnetic carrier particles with surface-bound gene vectors toward the bottom of the chamber for transfection with target cells. We study particle transport and accumulation as a function of key variables. Our analysis indicates that the particles are magnetically focused toward the center of the chamber during transport, and that the rate of accumulation at the base can be enhanced using larger particles and/or by reducing the spacing between the magnet and the chamber. The model provides insight into the physics of particle transport at the nanoscale and enables rapid parametric analysis of particle accumulation, which is useful for optimizing novel magnetofection systems.

  11. Biogenic nanoscale colloids in wastewater effluents.

    PubMed

    Song, Guixue; Wang, Jun; Chiu, Chao-An; Westerhoff, Paul

    2010-11-01

    The size, surface area, metal complexation capacity, organic pollutant sorption potential, reactivity with disinfectants, and elevated nitrogen content of biogenic organic nanoscale material (BONM) can potentially affect aquatic environments. BONM in effluents from 11 full-scale wastewater treatment plants (WWTPs), which use a range of biological processes, were characterized in two ways. First, BONM was measured by hydrodynamic size-exclusion chromatography coupled with an online organic carbon and UV detector. Second, BONM was isolated from the wastewater using rotary evaporation and dialysis and then characterized by elemental analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The wastewaters contained 6-10 mg/L of dissolved organic carbon (DOC). BONM accounted for 5%-50% of the DOC in wastewater effluent organic matter, and the largest size fraction (>10 kDa) of organic carbon correlated with the organic carbon content determined after rotary evaporation and dialysis. Membrane bioreactor WWTPs had the lowest fraction of BONM (<10% of the DOC), followed by conventional activated sludge (10% to 30% of the DOC), with other processes (e.g., trickling filters, aerated lagoons) containing larger BONM percentages. BONM had a lower carbon to nitrogen ratio (6.2 ± 1.7) compared with the literature values for humic or fulvic acids, exhibited chemical bonds that were indicative of amides and polysaccharides, and contained fibril entangled networks. This work has important implications for operations efficiency of WWTPs, including controlling membrane fouling and release of organic nitrogen into sensitive environments. PMID:20886826

  12. Energy-harvesting at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Jordan, Andrew; Sothmann, Björn; Sánchez, Rafael; Büttiker, Markus

    2013-03-01

    Energy harvesting is the process by which energy is taken from the environment and transformed to provide power for electronics. Specifically, the conversion of thermal energy into electrical power, or thermoelectrics, can play a crucial role in future developments of alternative sources of energy. Unfortunately, present thermoelectrics have low efficiency. Therefore, an important task in condensed matter physics is to find new ways to harvest ambient thermal energy, particularly at the smallest length scales where electronics operate. To achieve this goal, there is on one hand the miniaturizing of electrical devices, and on the other, the maximization of either efficiency or power the devices produce. We will present the theory of nano heat engines able to efficiently convert heat into electrical power. We propose a resonant tunneling quantum dot engine that can be operated either in the Carnot efficient mode, or maximal power mode. The ability to scale the power by putting many such engines in a ``Swiss cheese sandwich'' geometry gives a paradigmatic system for harvesting thermal energy at the nanoscale.

  13. Atomistic simulations of nanoscale electrokinetic transport

    NASA Astrophysics Data System (ADS)

    Liu, Jin; Wang, Moran; Chen, Shiyi; Robbins, Mark

    2011-11-01

    An efficient and accurate algorithm for atomistic simulations of nanoscale electrokinetic transport will be described. The long-range interactions between charged molecules are treated using the Particle-Particle Particle-Mesh method and the Poisson equation for the electric potential is solved using an efficient multi-grid method in physical space. Using this method, we investigate two important applications in electrokinetic transport: electroosmotic flow in rough channels and electowetting on dielectric (EWOD). Simulations of electroosmotic and pressure driven flow in exactly the same geometries show that surface roughness has a much more pronounced effect on electroosmotic flow. Analysis of local quantities shows that this is because the driving force in electroosmotic flow is localized near the wall where the charge density is high. In atomistic simulations of EWOD, we find the contact angle follows the continuum theory at low voltages and always saturates at high voltages. Based on our results, a new mechanism for saturation is identified and possible techniques for controlling saturation are proposed.

  14. Nanoscale glucan polymer network causes pathogen resistance

    PubMed Central

    Eggert, Dennis; Naumann, Marcel; Reimer, Rudolph; Voigt, Christian A.

    2014-01-01

    Successful defence of plants against colonisation by fungal pathogens depends on the ability to prevent initial penetration of the plant cell wall. Here we report that the pathogen-induced (1,3)-?-glucan cell wall polymer callose, which is deposited at sites of attempted penetration, directly interacts with the most prominent cell wall polymer, the (1,4)-?-glucan cellulose, to form a three-dimensional network at sites of attempted fungal penetration. Localisation microscopy, a super-resolution microscopy technique based on the precise localisation of single fluorescent molecules, facilitated discrimination between single polymer fibrils in this network. Overexpression of the pathogen-induced callose synthase PMR4 in the model plant Arabidopsis thaliana not only enlarged focal callose deposition and polymer network formation but also resulted in the exposition of a callose layer on the surface of the pre-existing cellulosic cell wall facing the invading pathogen. The importance of this previously unknown polymeric defence network is to prevent cell wall hydrolysis and penetration by the fungus. We anticipate our study to promote nanoscale analysis of plant-microbe interactions with a special focus on polymer rearrangements in and at the cell wall. Moreover, the general applicability of localisation microscopy in visualising polymers beyond plant research will help elucidate their biological function in complex networks. PMID:24561766

  15. Primary thermometry with nanoscale tunnel junctions

    SciTech Connect

    Hirvi, K.P.; Kauppinen, J.P.; Paalanen, M.A.; Pekola, J.P. [Univ. of Jyvaskyla (Finland)

    1995-10-01

    We have found current-voltage (I-V) and conductance (dI/dV) characteristics of arrays of nanoscale tunnel junctions between normal metal electrodes to exhibit suitable features for primary thermometry. The current through a uniform array depends on the ratio of the thermal energy k{sub B}T and the electrostatic charging energy E{sub c} of the islands between the junctions and is completely blocked by Coulomb repulsion at T=0 and at small voltages eV/2 {<=} Ec. In the opposite limit, k{sub B}T {much_gt} E{sub c}, the width of the conductance minimum scales linearly and universally with T and N, the number of tunnel junctions, and qualifies as a primary thermometer. The zero bias drop in the conductance is proportional to T{sup -1} and can be used as a secondary thermometer. We will show with Monte Carlo simulations how background charge and nonuniformities of the array will affect the thermometer.

  16. Magnetically Driven Swimming of Nanoscale Colloidal Assemblies

    NASA Astrophysics Data System (ADS)

    Breidenich, Jennifer; Benkoski, Jason; Baird, Lance; Deacon, Ryan; Land, H. Bruce; Hayes, Allen; Keng, Pei; Pyun, Jeffrey

    2009-03-01

    At microscopic length scales, locomotion can only be generated through asymmetric conformation changes, such as the undulating flagellum employed by protozoa. This simple yet elegant design is optimized according to the dueling needs of miniaturization and the fluid dynamics of the low Reynolds number environment. In this study, we fabricate nanoscale colloidal assemblies that mimic the head + tail structure of flagellates. The assemblies consist of two types of magnetic colloids: 25 nm polystyrene-coated Co nanoparticles, and 250 nm polyethylene glycol coated magnetite nanoparticles. When mixed together in N-dimethylformamide, the Co nanoparticles assemble into flexible, segmented chains ranging in length from 1 - 5 ?m. These chains then attach at one end to the larger magnetic beads due to magnetic attraction. This head + tail structure aligns with an external uniform magnetic field and is actuated by an oscillating transverse field. We examine the effects of Co nanoparticle concentration, magnetite bead concentration, magnetic field strength, and oscillation frequency on the formation of swimmers and the speed of locomotion.

  17. Peptide assembly for nanoscale control of materials

    NASA Astrophysics Data System (ADS)

    Pochan, Darrin

    2011-03-01

    Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic, charged synthetic molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. Design strategies for materials self-assembly based on small (less than 24 amino acids) beta-hairpin peptides will be discussed. Self-assembly of the peptides is predicated on an intramolecular folding event caused by desired solution properties. Importantly, kinetics of self-assembly can be tuned in order to control gelation time. The final gel behaves as a shear thinning, but immediately rehealing, solid that is potentially useful for cell injection therapies. The morphological, and viscoelastic properties of these peptide hydrogels will be discussed. In addition, slight changes in peptide primary sequence can have drastic effects on the self-assembled morphology. Additional sequences will be discussed that do not form hydrogels but rather form nanoscale templates for inorganic material assembly.

  18. Fabrication of a nanoscale electric field sensor

    NASA Astrophysics Data System (ADS)

    Zheng, Yun; King, Todd; Stewart, Daniel; Getty, Stephanie

    2009-05-01

    A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust devils. The sensor was fabricated using MEMS techniques, integrated at the system level, and deployed during a dust devil field campaign. The two-terminal piezoresistive sensor consists of a micron-scale network of suspended singlewalled carbon nanotubes (SWCNTs) that are mechanically coupled to a free-standing electrically conductor. Electrostatic coupling of the conductor to the electric field is expected to produce a deflection of the conductor and a corresponding change in nanotube device resistance, based on the known piezoresistive properties of SWCNTs. The projected device performance will allow measurement of the large electric fields for large dust devils without saturation. With dimensions on the 100 ?m scale and power consumption of only tens of nW, the sensor features dramatically reduced mass, power, and footprint. Recent field testing of the sensor demonstrated the robustness of suspended SWCNT devices to temperature fluctuations, mechanical shock, dust, and other environmental factors.

  19. PVD Ti-films for plasma-facing first walls, Part I: Characterization of surface chemistry during H2 and O2 exposure

    NASA Astrophysics Data System (ADS)

    Tankut, A.; Miller, K. E.; Ohuchi, F. S.

    2013-02-01

    A surface analysis study was carried out to investigate the gettering behavior of PVD Ti films in ambiences pertinent to plasma research experiments. By controlling the type and amount of gas flux, the effect of wall history on the Ti chemical pumping of H2 and O2 was studied using X-ray photoelectron spectroscopy (XPS). The Ti-2p XPS spectra at various gas exposure stages were interpreted using reference spectra obtained at selected conditions. Our findings are in accord with some of the previously reported notions regarding Ti pumping of hydrogen and oxygen; (a) hydrogen is pumped by Ti until all available sites are filled, and (b) oxygen exposure on Ti results in a passive surface oxide layer which inhibits further oxidation as well as hydride formation. However, our observations conflict the understanding that oxygen pumping of Ti is not affected by previous hydrogen absorption. In contrast, when exposed to O2, Ti films that were previously exposed to H2 yielded considerably lower oxidation compared to unexposed Ti films.

  20. Design of interpenetrated networks of mesostructured hybrid silica and nonconductive poly(vinylidene fluoride)-cohexafluoropropylene (PVdF-HFP) polymer for proton exchange membrane fuel cell applications.

    PubMed

    Pereira, Franck; Chan, Alida; Vallé, Karine; Palmas, Pascal; Bigarré, Janick; Belleville, Philippe; Sanchez, Clément

    2011-05-01

    Organic-inorganic hybrid membranes of poly(vinylidene fluoride)-cohexafluoropropylene (PVdF-HFP) and mesostructured silica containing sulfonic acid groups were synthesized by using the sol-gel process. These hybrid membranes were prepared by in situ co-condensation of tetraethoxysilane and an organically modified silane (ormosil) by a self-assembly route using organic surfactants as templates for tuning the architecture of the hybrid organosilica component. In this paper, we describe the elaboration and characterization of hybrid membranes all the way from the precursor solution to the evaluation of the fuel cell performances. These hybrid materials were extensively characterized by using NMR and IR spectroscopy, electron microscopy, or impedance spectroscopy so as to determinate their physicochemical and electrochemical properties. Even though the ion-exchange capacity (IEC) was quite weak, the first fuel cell tests performed with these hybrid membranes show promising results relative to optimized Nafion 112 thanks to great water management of the silica inside the hydrophobic polymer. PMID:21360682

  1. Effect of PVD process parameters on the quality and reliability of thin (10-30 nm) Al2O3 dielectrics

    NASA Astrophysics Data System (ADS)

    Dutta, Shibesh; Ramesh, Sivaramakrishnan; Shankar, Balakrishnan; Gopalan, Sundar

    2012-03-01

    Over the last decade, dielectric scaling in non-volatile memories (NVM) and CMOS logic applications has reached a point where better innovations will be required to meet the reliability and performance requirements of future products. For both these applications, high k materials are being explored as possible candidates to replace the traditional SiO2 and oxide/nitride/oxide-based films used today. While there are several attractive candidates to replace these materials, HfO2 and Al2O3 are considered as the most promising ones. Although there has been a lot of work on CVD-based Al2O3, there has not been much reported for PVD-based Al2O3 for NVM applications, especially in the thickness regime of 10-30 nm. This paper discusses the effects of process parameters such a plasma power and annealing conditions on the quality of Al2O3 dielectrics. It was observed that a post deposition anneal in O2 ambient at 700°C for 15 s is essential to obtain a fully oxidized film with high density. While higher power (1,500 W) results in thicker films with better k values, they also lead to more substrate damage and poorer reliability. Annealing done at temperatures greater than 700°C for 60 s or more results in failure of the film possibly due to diffusion of silicon into Al2O3 and its subsequent reaction.

  2. A MULTILAYER BIOCHEMICAL DRY DEPOSITION MODEL 1. MODEL FORMULATION

    EPA Science Inventory

    A multilayer biochemical dry deposition model has been developed based on the NOAA Multilayer Model (MLM) to study gaseous exchanges between the soil, plants, and the atmosphere. Most of the parameterizations and submodels have been updated or replaced. The numerical integration ...

  3. Multilayer laser printing for Organic Thin Film Transistors

    Microsoft Academic Search

    Ludovic Rapp; Sébastien Nénon; Anne Patricia Alloncle; Christine Videlot-Ackermann; Frédéric Fages; Philippe Delaporte

    2011-01-01

    Functional laser printed Organic Thin Film Transistors (OTFTs) have been achieved from multilayer substrates composed with semiconductor and electrodes. The p-type copper phthalocyanine (CuPc) was used to form the active layer. Different kinds of metallic materials were used for source and drain electrodes. Multilayer donor substrates were prepared by the successive depositions of materials by either thermal evaporation under vacuum

  4. Matrix techniques for modeling ultrasonic waves in multilayered media

    Microsoft Academic Search

    Michael J. S. Lowe

    1995-01-01

    Research into ultrasonic NDE techniques for the inspection of multilayered structures relies strongly on the use of modeling tools which calculate dispersion curves and reflection and transmission spectra. These predictions are essential to enable the best inspection strategies to be identified and their sensitivities to be evaluated. General purpose multilayer modeling tools may be developed from a number of matrix

  5. Multi-layer laminate structure and manufacturing method

    SciTech Connect

    Keenihan, James R. (Midland, MI); Cleereman, Robert J. (Midland, MI); Eurich, Gerald (Merrill, MI); Graham, Andrew T. (Midland, MI); Langmaid, Joe A. (Caro, MI)

    2012-04-24

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  6. Multi-layer laminate structure and manufacturing method

    DOEpatents

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2013-01-29

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  7. Design and Optimization of Wideband Multilayer Printed Antenna Arrays

    E-print Network

    Design and Optimization of Wideband Multilayer Printed Antenna Arrays B. Riviere, Dr. H. Jeuland of ONERA recent research work in the field of wideband printed antenna arrays. A special focus will be given to the comprehensive analysis and design optimization of multilayered printed arrays for wide

  8. Film stress studies and the multilayer laue lens project.

    SciTech Connect

    Liu, C.; Conley, R.; Macrander, A. T.; X-Ray Science Division

    2006-01-01

    A Multilayer Laue Lens (MLL) is a new type of linear zone plate, made by sectioning a planar depth-graded multilayer and used in Laue transmission diffraction geometry, for nanometer-scale focusing of hard x-rays. To produce an MLL, a depth-graded multilayer consisting of thousands of layers with a total thickness of tens of microns is needed. Additionally, the multilayer wafer has to be sectioned and polished to a thickness of {approx}10 to 25 microns to yield a diffracting grating to focus x-rays. The multilayers must have both low stress and good adhesion to survive the subsequent cutting and polishing processes, as well as sharp interfaces and accurate layer placement. Several partial MLLs using WSi{sub 2}/Si multilayers with precise zone-plate structures have been successfully fabricated. A W/Si multilayer with the same structure, however, cracked and peeled off from the Si substrate after it was grown. Here we report results of our film stress studies of dc magnetron-sputtered WSi{sub 2}, W, and Mo thin films and WSi{sub 2}/Si, W/Si, and Mo/Si multilayers grown on Si(100) substrates. The stress measurements were carried out using a stylus profiler to measure the curvatures of 2-inch-diameter, 0.5-mm-thick Si(100) wafers before and after each coating. The physical origins of the stress and material properties of these systems will be discussed.

  9. Nonspecular scattering from multilayer mirrors at normal incidence

    Microsoft Academic Search

    Eric M. Gullikson; Daniel G. Stearns; David P. Gaines; James H. Underwood

    1997-01-01

    The first measurements are reported of non-specular scattering of EUV radiation normally incident on a multilayer mirror. The scattering from a Mo\\/Si multilayer mirror has been measured as a function of angle and wavelength. A peak in the angular distribution of scattered light is observed which is due to the correlation of the roughness of different interfaces. The scattering from

  10. Asymmetric extreme ultraviolet scattering from sputter-deposited multilayers

    Microsoft Academic Search

    E. M. Gullikson; D. G. Stearns

    1999-01-01

    Asymmetric scattering of extreme ultraviolet light is observed from Mo\\/Si multilayers at normal incidence. The observed asymmetry is shown to depend on the geometry of the multilayer film deposition. However, atomic force microscopy (AFM) measurements of the top surface were isotropic, and there was no indication of columnar film growth either in the AFM or in TEM cross-sectional measurements. The

  11. Mitigation of substrate defects in reticles using multilayer buffer layers

    Microsoft Academic Search

    Paul B. Mirkarimi; Sasa Bajt; Daniel G. Stearns

    2001-01-01

    A multilayer film is used as a buffer layer to minimize the size of defects on a reticle substrate prior to deposition of a reflective coating on the substrate. The multilayer buffer layer deposited intermediate the reticle substrate and the reflective coating produces a smoothing of small particles and other defects on the reticle substrate. The reduction in defect size

  12. Multilayer, Front-Contact Grid for Solar Cells

    NASA Technical Reports Server (NTRS)

    Milnes, A. G.; Flat, A.

    1982-01-01

    Proposed multilayer, front-contact grid structure for solar cells optimizes collection of photogenerated current with minimum power losses. It is constructed of several layers of conducting grids. With multilayer concept, peak efficiency can occur at higher output-power levels. Because of this, higher solar concentrations can be applied to solar-cell arrays.

  13. Structure and Molecular Dynamics of Multilayered Polycarbonate/Polystyrene Films

    E-print Network

    Paris-Sud XI, Université de

    Structure and Molecular Dynamics of Multilayered Polycarbonate/Polystyrene Films M. Walczak,1 W (wileyonlinelibrary.com). ABSTRACT: Multilayered film polycarbonate/polysty- rene (PC/PS) comprising 257 layers Periodi- cals, Inc. J Appl Polym Sci 000: 000­000, 2012 Key words: interface; polystyrene; polycarbonate

  14. Multi-layer boron thin-film detectors for neutrons

    Microsoft Academic Search

    Zhehui Wang; Christopher L Morris

    2010-01-01

    Intrinsic efficiencies of the multilayer boron detectors have been examined both theoretically and experimentally. It is shown that due to the charge loss in the boron layers, the practical efficiencies of most multi-layer ¹°B detectors are limited up to about 42%, much less than 77% of the 2 bar 2-inch diameter ³He detectors. It is suggested that the same charge

  15. CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS

    E-print Network

    Hart, Gus

    CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

  16. Optoelectrical Detection System Using Porous Silicon-Based Optical Multilayers

    Microsoft Academic Search

    Andras Kovacs; Prasad Jonnalagadda; Ulrich Mescheder

    2011-01-01

    Porous silicon-based multilayer structures for optical sensors have been simulated, fabricated and tested. The proper- ties of optical sensors using porous silicon multilayers can be ad- justed by appropriate substrate material, morphology, process pa- rameters in the pore formation process and by surface treatment (thermal oxidation). Heavily and lightly doped p-doped substrates have been used to realize porous silicon layers

  17. Effective theory of rotationally faulted multilayer graphene

    NASA Astrophysics Data System (ADS)

    Kindermann, Markus

    2012-02-01

    The crystal structure of graphene multilayers with an interlayer twist is characterized by Moir'e patterns with various commensurabilities. Also the electronic structure of the material, which grows for instance epitaxially on SiC, is remarkably rich. In this talk an effective low-energy description of such multilayers will be discussed. In certain limits the theory reduces to a (single-layer) Dirac model with space-dependent potentials and mass term. The consequences of this theory will be explored and comparison with experiment will be made. The discussion of experimental consequences will focus on the Landau quantization in a magnetic field, where much experimental data is available. For instance, a spatially modulated splitting of the zeroth Landau level in the material has been observed through scanning tunneling spectroscopy [1]. That splitting finds a natural explanation in the space-dependent mass term of the presented theory [2]. Also a large low-field splitting of higher Landau levels recently observed in graphene multilayers [3] will be shown to follow from that theory. Finally, a theoretically expected [4] amplitude modulation of the Landau level wavefunctions on the top layer of the material will be discussed. [4pt] [1] D. L. Miller, K. D. Kubista, G. M. Rutter, M. Ruan, W. A. de Heer, M. Kindermann, P. N. First, and J. A. Stroscio, Nature Physics 6, 811 (2010). [0pt] [2] M. Kindermann and P. N. First, Phys. Rev. B 83, 045425 (2010). [0pt] [3] Y. J. Song, A. F. Otte, Y. Kuk, Y. Hu, D. B. Torrance, P. N. First, W. A. de Heer, H. Min, S. Adam, M. D. Stiles, A. H. MacDonald, and J. A. Stroscio, Nature 467, 185 (2010). [0pt] [4] M. Kindermann and E. G. Mele, Phys. Rev. B 84, 161406(R) (2011).

  18. Optics and multilayer coatings for EUVL systems

    SciTech Connect

    Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

    2008-03-21

    EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

  19. Static and dynamic properties of Fibonacci multilayers

    NASA Astrophysics Data System (ADS)

    Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

    2013-05-01

    We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures.

  20. Domain walls in antiferromagnetically coupled multilayer films.

    PubMed

    Hellwig, Olav; Berger, Andreas; Fullerton, Eric E

    2003-11-01

    We report experimentally observed magnetic domain-wall structures in antiferromagnetically coupled multilayer films with perpendicular anisotropy. Our studies reveal a first-order phase transition from domain walls with no net moment to domain walls with ferromagnetic cores. The transition originates from the competition between dipolar and exchange energies, which we tune by means of layer thickness. Although observed in a synthetic antiferromagnetic system, such domain-wall structures may be expected to occur in A-type antiferromagnets with anisotropic exchange coupling. PMID:14611609

  1. Multilayer insulation considerations for large propellant tanks

    NASA Astrophysics Data System (ADS)

    Nast, T. C.; Frank, D. J.; Feller, J.

    2014-11-01

    Multilayer insulation (MLI) systems for cryogenic instrument Dewars have demonstrated very high thermal performance in ground and orbit. Ground tests of insulation systems on propellant storage size tanks have shown performance and repeatability issues. This paper presents a summary of studies for National Aeronautics and Space Administration (NASA) focused on MLI systems on the larger Tankage. The sensitivity of boil off to MLI thermal conductivity is presented. The effect of compressions, assembly joints and MLI parameters are presented. A novel large tank simulator approach for MLI testing is presented along with recommendations for maturation of the MLI technology.

  2. Layer-resolved conductivities in multilayer graphene

    NASA Astrophysics Data System (ADS)

    Wakutsu, Takeo; Nakamura, Masaaki; Dóra, Balázs

    2012-01-01

    We study interlayer transport of multilayer graphenes in a magnetic field with various stacking structures (AB, ABC, and AA types) by calculating the Hall and longitudinal conductivities as functions of the Fermi energy. Their behavior depends strongly on the stacking structures and selection of the layers. The Hall conductivity between different layers is no longer quantized. Moreover, for AB stacking, the interlayer conductivity vanishes around zero energy with increasing layer separation, and shows negative values in particular cases. The fact that longitudinal interlayer conductivity is suppressed by a magnetic field indicates that this system can be applied as a switching device.

  3. Thin film photovoltaic device with multilayer substrate

    DOEpatents

    Catalano, Anthony W. (Rushland, PA); Bhushan, Manjul (Wilmington, DE)

    1984-01-01

    A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

  4. Co/Mg/X Multilayer Mirrors For the EUV Range

    SciTech Connect

    Hu, M.-H.; Le Guen, K.; Andre, J.-M.; Jonnard, P.; Zhou, S. K.; Li, H. Ch.; Zhu, J. T.; Wang, Z. S. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Institute of Precision Optical Engineering, Department of Physics, Tongji University, Shanghai 200092 (China)

    2010-04-06

    A new material combination namely Co/Mg multilayer designed for optics applications in the EUV range, is reported. Simulations show that reflectivity value of the Co/Mg multilayer can reach a reflectivity of 55% at 25.2 nm (49.2 eV), when the grazing incidence angle is set to 45 deg. and s polarization is considered. The introduction of additional materials, e.g., Y and Zr can improve the reflectivity to 61%. Co/Mg and Co/Mg/B{sub 4}C multilayers have been deposited following the parameters deduced from the simulations. The introduction of a B{sub 4}C barrier layer would in principle increase the multilayer reflectivity to 61%. In fact the reflectivity measurements at 0.154 nm show that the introduction of B{sub 4}C does not improve the structural quality of the multilayers.

  5. Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants

    PubMed Central

    Booth, Leigh; Catledge, Shane A.; Nolen, Dustin; Thompson, Raymond G.; Vohra, Yogesh K.

    2011-01-01

    With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios. PMID:21603588

  6. Fabrication, measurement, and analysis of multilayer x- ray diffraction gratings

    NASA Astrophysics Data System (ADS)

    Hansen, Douglas P.

    1997-12-01

    I examine the theory and fabrication of lamellar multilayer x-ray diffraction gratings. I use current theory based on the Kirchoff Integral for amplitude gratings and a new equation for phase gratings to analyze current technology multilayer grating performance (where the period/? exceeds 10). I examine the possible fabrication methods and define two general categories (additive: multilayer added to patterned substrate, subtractive: grating etched into multilayer). I conclude the additive approach is superior, leading to x-ray analogues to binary optics and holographic optical elements. I define an additive process in detail and demonstrate the serviceability of the key processes: thermal growth of silicon dioxide on silicon, lithography, a combined plasma-etch and wet-etch. Multilayer fabrication difficulties on patterned substrates are identified, including: mushroom cap growth, and filleting in the grooves. Measurements done at NSLS on 2 amplitude gratings and 1 phase grating are reported. The data is shown to be compatible with the Kirchoff theory.

  7. Controlled Release from Model Blended Polyelectrolyte Multilayer Films

    NASA Astrophysics Data System (ADS)

    Akgun, Bulent; Jang, Yeongseon; Satija, Sushil; Char, Kookheon

    2011-03-01

    We propose a new concept of controlled release platforms based on the model blended multilayer films composed of positively charged weak polyelectrolyte (linear poly(ethylenimine),LPEI) layer and blended layer with negatively charged strong (poly(sodium-4-styrene sulfonic acid),PSS) and weak (poly(methacrylic acid),PMAA) polyelectrolytes. The blended multilayer films ((LPEI/PSS:PMAA)n) with well-defined internal structure are prepared by spin-assisted LbL deposition method, and their release behavior is systematically characterized with combined techniques of neutron reflectivity, ellipsometry, AFM, QCM and FT-IR. Since PSS provides the robust skeleton within the multilayer films independently on pH variation, the burst erosion of multilayer films is dramatically suppressed, and the release kinetics of PMAA can be precisely controlled by simply changing PSS contents within the multilayer films.

  8. Design of Surface Modifications for Nanoscale Sensor Applications

    PubMed Central

    Reimhult, Erik; Höök, Fredrik

    2015-01-01

    Nanoscale biosensors provide the possibility to miniaturize optic, acoustic and electric sensors to the dimensions of biomolecules. This enables approaching single-molecule detection and new sensing modalities that probe molecular conformation. Nanoscale sensors are predominantly surface-based and label-free to exploit inherent advantages of physical phenomena allowing high sensitivity without distortive labeling. There are three main criteria to be optimized in the design of surface-based and label-free biosensors: (i) the biomolecules of interest must bind with high affinity and selectively to the sensitive area; (ii) the biomolecules must be efficiently transported from the bulk solution to the sensor; and (iii) the transducer concept must be sufficiently sensitive to detect low coverage of captured biomolecules within reasonable time scales. The majority of literature on nanoscale biosensors deals with the third criterion while implicitly assuming that solutions developed for macroscale biosensors to the first two, equally important, criteria are applicable also to nanoscale sensors. We focus on providing an introduction to and perspectives on the advanced concepts for surface functionalization of biosensors with nanosized sensor elements that have been developed over the past decades (criterion (iii)). We review in detail how patterning of molecular films designed to control interactions of biomolecules with nanoscale biosensor surfaces creates new possibilities as well as new challenges. PMID:25594599

  9. Calcium Binding-Mediated Sustained Release of Minocycline from Hydrophilic Multilayer Coatings Targeting Infection and Inflammation

    PubMed Central

    Zhang, Zhiling; Nix, Camilla A.; Ercan, Utku K.; Gerstenhaber, Jonathan A.; Joshi, Suresh G.; Zhong, Yinghui

    2014-01-01

    Infection and inflammation are common complications that seriously affect the functionality and longevity of implanted medical implants. Systemic administration of antibiotics and anti-inflammatory drugs often cannot achieve sufficient local concentration to be effective, and elicits serious side effects. Local delivery of therapeutics from drug-eluting coatings presents a promising solution. However, hydrophobic and thick coatings are commonly used to ensure sufficient drug loading and sustained release, which may limit tissue integration and tissue device communications. A calcium-mediated drug delivery mechanism was developed and characterized in this study. This novel mechanism allows controlled, sustained release of minocycline, an effective antibiotic and anti-inflammatory drug, from nanoscale thin hydrophilic polyelectrolyte multilayers for over 35 days at physiologically relevant concentrations. pH-responsive minocycline release was observed as the chelation between minocycline and Ca2+ is less stable at acidic pH, enabling ‘smart’ drug delivery in response to infection and/or inflammation-induced tissue acidosis. The release kinetics of minocycline can be controlled by varying initial loading, Ca2+ concentration, and Ca2+ incorporation into different layers, enabling facile development of implant coatings with versatile release kinetics. This drug delivery platform can potentially be used for releasing any drug that has high Ca2+ binding affinity, enabling its use in a variety of biomedical applications. PMID:24409292

  10. Dielectric structure pyrotechnic initiator realized by integrating Ti/CuO-based reactive multilayer films

    NASA Astrophysics Data System (ADS)

    Zhu, Peng; Shen, Ruiqi; Fiadosenka, N. N.; Ye, Yinghua; Hu, Yan

    2011-04-01

    A dielectric structure pyrotechnic initiator was proposed and the initiator samples were designed and realized by integrating Ti/CuO-based reactive multilayer films on ceramic substrate. The dielectric structure consists of essentially two titanium films separated by a copper oxide (CuO) film, which is just like as a capacitor guaranteeing the initiator will not be discharged until the external voltage has exceeded the breakdown strength of the CuO film. Results of the electrical explosion experiment show that the breakdown strength of 1-?m-thick CuO film is 60 V, and the initiator has "late time discharge" characteristics, which will improve the conversion ratio of the electricity greatly, and there is a nanoscale exothermic reaction in the electrical explosion process. A systematic temperature measurement model based on the "double-line atomic emission spectroscopy of copper element" was presented and used to test the explosion temperature and duration. The ejected explosion flame was seen clearly with a potential temperature exceeding 4500 K for 0.1 ms, 4250 K for 0.35 ms, and 4000 K for 0.5 ms. Besides, electric energy and exothermic reaction create high-temperature products, which discharge to a distance of 1 cm or more. The high temperature and ejected products may be able to ignite the attached energetic materials even if the initiator makes no physical contact. These characteristics of the initiator may open a door to the preparation of the highly efficient and insensitive initiating explosive device.

  11. Boundary integral spectral element method analyses of extreme ultraviolet multilayer defects.

    PubMed

    Niu, Jun; Luo, Ma; Fang, Yuan; Liu, Qing Huo

    2014-10-01

    Extreme ultraviolet (EUV) lithography is an emerging technology for high-density semiconductor patterning. Multilayer distortion caused by mask defects is regarded as one of the critical challenges of EUV lithography. To simulate the influence of the defected nanoscale structures with high accuracy and efficiency, we have developed a boundary integral spectral element method (BI-SEM) that combines the SEM with a set of surface integral equations. The SEM is used to solve the interior computational domain, while the open boundaries are truncated by the surface integral equations. Both two-dimensional (2D) and three-dimensional (3D) EUV cases are simulated. Through comparing the performance of this method with the conventional finite element method (FEM), it is shown that the proposed BI-SEM can greatly decrease both the memory cost and the computation time. For typical 2D problems, we show that the BI-SEM is 11 and 1.25 times more efficient than the FEM in terms of memory and CPU time, respectively, while for 3D problems, these factors are over 14 and 2, respectively, for smaller problems; realistic 3D problems that cannot be solved by the conventional FEM can be accurately simulated by the BI-SEM. PMID:25401246

  12. Nanoscale Metal Oxide Semiconductors for Gas Sensing

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

    2011-01-01

    A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical resistance of these SnO2 nanomaterials towards reducing gases. With regard to the sensitivity of the different nascent nanostructures, the electrospun nanofibers appear preferable

  13. Building nanoscale devices with semiconducting nanowires

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyong

    Quasi-one-dimensional (Q1D) nanostructures such as nanotubes and nanowires have been widely regarded as the potential building blocks for nanoscale electronic, optoelectronic and sensing devices. In our work, several types of semiconducting nanowires, including zinc oxide (ZnO) nanowires, gallium oxide (Ga2O 3) nanowires, etc, have been successfully synthesized with chemical vapor deposition method. The crystal structures of the as grown nanostructures were characterized by electron microscopies which revealed their high crystallinity. Along with other Q1D nanostructures, such as silver-tetracyanoquinodimethane (Ag-TCNQ) nanowires and iron oxide (Fe2O3) nanobelts, they were fabricated into field-effect transistors, photodetectors, electrical switching device with memory effect and chemical sensors with techniques including electron beam lithography, photolithography and focus ion beam. The physical properties studies were carried out with these devices. The electrical transport studies revealed the carrier concentration and field-effect mobility of the nanowire transistors. Photoconduction studies were performed on individual nanowires, these nanowires only functioned as optically gated transistors, but also demonstrated polarization dependent photodetection behavior originated from their quasi-one-dimensional nature. Due to the small diameter and controllable electron concentration, semiconducting nanowire transistors were implemented as highly sensitive chemical sensors with ability to detect various toxic gases. To fully utilize the scaling advantage of the Q1D structures, we developed a series of process to fabricate high density ZnO nanowire arrays inside dielectric templates. The electrical transport and photoconduction property of the individual nanowires in arrays were characterized with conductive scanning probe microscopy. Finally, the designs of vertical nanowire transistors based on such high density nanowire array will be demonstrated. These works pave the way of using semiconducting nanowires for integrated nanoelectronics and photonics.

  14. Thermal contact resistance across nanoscale silicon dioxide and silicon Jie Chen, Gang Zhang, and Baowen Li

    E-print Network

    Li, Baowen

    Thermal contact resistance across nanoscale silicon dioxide and silicon interface Jie Chen, Gang://jap.aip.org/about/rights_and_permissions #12;Thermal contact resistance across nanoscale silicon dioxide and silicon interface Jie Chen,1 Gang

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

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

  16. 77 FR 56681 - Nanoscale Science, Engineering, and Technology Subcommittee; Committee on Technology, National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-13

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

  17. 77 FR 61448 - Nanoscale Science, Engineering and Technology Subcommittee Committee on Technology, National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-09

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

  18. 78 FR 24241 - Nanoscale Science, Engineering, and Technology Subcommittee; Committee on Technology, National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-24

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

  19. NEST Scientific Report 2007-2009 Interferometry and entanglement detection at the nanoscale

    E-print Network

    Abbondandolo, Alberto

    and entanglement detection at the nanoscale NEST Scientific Report 2007-200952 the technical difficultiesNEST Scientific Report 2007-2009 Interferometry and entanglement detection at the nanoscale 51 F

  20. Multilayer optics for advanced X-ray applications; Proceedings of the Meeting, San Diego, CA, July 22, 23, 1991

    NASA Astrophysics Data System (ADS)

    Ceglio, Natale M.

    1992-01-01

    Topics discussed in these proceedings include multilayer fabrication and characterization, applications of multilayer technology, and damage and survivability of multilayer mirrors. Papers are presented on high-performance multilayer mirrors for soft X-ray projection lithography, multilayer coatings on figured optics, a simulation of the growth of Mo/Si multilayers, boron-based multilayers for soft X-ray optics, reflection masks for soft X-ray projection lithography, and multilayer mirrors for XUV Ge laser wavelengths. Attention is also given to soft X-ray reflectometry of multilayer coatings using a laser-plasma source, annealing studies of Ru/Si multilayer by high-angle annular dark-field microscopy and HREM, the fabrication and characterization of beryllium-based multilayer mirrors for soft X-rays, structural changes induced by thermal annealing in W/C multilayers, thermal stability of Mo/Si multilayers, and repair of high-performance multilayer coatings.