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Sample records for nanoscale multilayer pvd

  1. A chemically stable PVD multilayer encapsulation for lithium microbatteries

    NASA Astrophysics Data System (ADS)

    Ribeiro, J. F.; Sousa, R.; Cunha, D. J.; Vieira, E. M. F.; Silva, M. M.; Dupont, L.; Goncalves, L. M.

    2015-10-01

    A multilayer physical vapour deposition (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD deposition techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 ? ?m was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour deposition (CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber.

  2. Residual stress within nanoscale metallic multilayer systems during thermal cycling

    DOE PAGESBeta

    Economy, David Ross; Cordill, Megan Jo; Payzant, E. Andrew; Kennedy, Marian S.

    2015-09-21

    Projected applications for nanoscale metallic multilayers will include wide temperature ranges. Since film residual stress has been known to alter system reliability, stress development within new film structures with high interfacial densities should be characterized to identify potential long-term performance barriers. To understand factors contributing to thermal stress evolution within nanoscale metallic multilayers, stress in Cu/Nb systems adhered to Si substrates was calculated from curvature measurements collected during cycling between 25 °C and 400 °C. Additionally, stress within each type of component layers was calculated from shifts in the primary peak position from in-situ heated X-ray diffraction. The effects ofmore »both film architecture (layer thickness) and layer order in metallic multilayers were tracked and compared with monolithic Cu and Nb films. Analysis indicated that the thermoelastic slope of nanoscale metallic multilayer films depends on thermal expansion mismatch, elastic modulus of the components, and also interfacial density. The layer thickness (i.e. interfacial density) affected thermoelastic slope magnitude while layer order had minimal impact on stress responses after the initial thermal cycle. When comparing stress responses of monolithic Cu and Nb films to those of the Cu/Nb systems, the nanoscale metallic multilayers show a similar increase in stress above 200 °C to the Nb monolithic films, indicating that Nb components play a larger role in stress development than Cu. Local stress calculations from X-ray diffraction peak shifts collected during heating reveal that the component layers within a multilayer film respond similarly to their monolithic counterparts.« less

  3. Deposition of nanoscale multilayer CrN/NbN physical vapor deposition coatings by high power impulse magnetron sputtering

    SciTech Connect

    Purandare, Y. P.; Ehiasarian, A. P.; Hovsepian, P. Eh.

    2008-03-15

    Nanoscale multilayer CrN/NbN physical vapor deposition (PVD) coatings are gaining reputation for their high corrosion and wear resistance. However, the CrN/NbN films deposited by ABS (arc bond sputtering) technology have some limitations such as macrodroplets, porosity, and less dense structures. The novel HIPIMS (high power impulse magnetron sputtering) technique produces macroparticle-free, highly ionized metal plasma, which brings advantages in both surface pretreatment and coating deposition stages of the PVD process. In this study, nanoscale multilayer CrN/NbN PVD coatings were pretreated and deposited with HIPIMS technology and compared with those deposited by HIPIMS-UBM (unbalanced magnetron) and by the ABS technique. In all cases Cr{sup +} etching was utilized to enhance adhesion by low energy ion implantation. The coatings were deposited at 400 deg. C with substrate biased (U{sub b}) at -75 V. During coating deposition, HIPIMS produced significantly high activation of nitrogen compared to the UBM as observed with mass spectroscopy. HIPIMS-deposited coatings revealed a bilayer period of 4.1 nm (total thickness: 2.9 {mu}m) and hardness of 3025 HK{sub 0.025}. TEM results revealed droplet free, denser microstructure with (200) preferred orientation for the HIPIMS coating owing to the increased ionization as compared to the more porous structure with random orientation observed in UBM coating. The dry sliding wear coefficient (K{sub c}) of the coating was 1.8x10{sup -15} m{sup 3} N{sup -1} m{sup -1}, whereas the steady state coefficient of friction was 0.32. Potentiodynamic polarization tests revealed higher E{sub corr} values, higher pitting resistance (around potentials +400 to +600 mV), and lower corrosion current densities for HIPIMS deposited coatings as compared to the coatings deposited by ABS or HIPIMS-UBM. The corrosion behavior of the coatings qualitatively improved with the progressive use of HIPIMS from pretreatment stage to the coating deposition step.

  4. The mechanical behavior of nanoscale metallic multilayers: A survey

    NASA Astrophysics Data System (ADS)

    Zhou, Q.; Xie, J. Y.; Wang, F.; Huang, P.; Xu, K. W.; Lu, T. J.

    2015-06-01

    The mechanical behavior of nanoscale metallic multilayers (NMMs) has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of microlaminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size-dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plastic deformation physics of NMMs. We hope this review could accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to scientists and engineers working on NMM systems, and (2) providing a better understanding of interface behavior and the exceptional qualities the interfaces in NMMs display at atomic scale.

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

    SciTech Connect

    Wang, Z.; Perepezko, J. H.

    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.

  6. Effect of a ductility layer on the tensile strength of TiAl-based multilayer composite sheets prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing; Zhang, Yaoyao; Liu, Qiang; Chen, Guiqing; Zhang, Deming

    2014-09-15

    TiAl/Nb and TiAl/NiCoCrAl laminate composite sheets with a thickness of 0.4–0.6 mm and dimensions of 150 mm × 100 mm were successfully fabricated by electron beam physical vapor deposition. The microstructures of the sheets were examined, and their mechanical properties were compared with those of TiAl monolithic sheet produced by electron beam physical vapor deposition. Tensile testing was performed at room temperature and 750 °C, and the fracture surfaces were examined by scanning electron microscopy. Among the three microlaminate sheets, the TiAl/NiCoCrAl micro-laminate sheet had the best comprehensive properties at room temperature, and the TiAl/Nb micro-laminate sheet showed the ideal high-temperature strength and plasticity at 750 °C. The result was discussed in terms of metal strengthening mechanism. - Highlights: • TiAl-based multilayer foils was fabricated successfully by using EB-PVD method; • The tensile properties and micro-fracture morphologies of the sheet were investigated; • The deformation behavior of the multilayer foils was discussed.

  7. Microstructure evolution during annealing of TiAl/NiCoCrAl multilayer composite prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing; Zhang, Deming; Chen, Guiqing; Wang, Yuesheng

    2014-07-01

    TiAl/NiCoCrAl laminate composite sheet with a thickness of 0.4–0.6 mm as well as a dimension of 150 mm × 100 mm was fabricated successfully by using electron beam physical vapor deposition (EB-PVD) method. The annealing treatment was processed at 1123 and 1323 K for 3 h in a high vacuum atmosphere, respectively. The phase composition and microstructure of TiAl/NiCoCrAl microlaminated sheet have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the sheet characterization and results of the microstructure evolution during annealing treatment process, the diffusion mechanism of interfacial reaction in TiAl/NiCoCrAl microlaminate was investigated and discussed.

  8. Oxidation performance of nano-scale multilayer coatings on ?-TiAl

    NASA Astrophysics Data System (ADS)

    Ross, I. M.; Rainforth, W. M.; Zhou, Z.; Walker, J. C.; Reinhard, C.; Ehiasarian, A. P.; Hovsepian, P. E.; Braun, R.

    2008-08-01

    There is a major drive to introduce ?-TiAl into gas turbine engines in order to reduce weight. However, this will require the development of coatings that protect against oxidation at high temperature, but do not adversely affect the mechanical properties. This work reports the high temperature degradation mechanisms of a nanoscale CrAlYN/CrN multilayer coating deposited on ?-TiAl(8Nb) by a combined high power impulse magnetron sputtering / unbalanced magnetron sputtering. Detailed TEM/STEM of FIB prepared specimens from isothermal static oxidation tests at 850°C for up to 1030 hours is presented. The evolution of the complex oxide structure and the implications for future coating development is discussed.

  9. Fabrication and characterization of reactive nanoscale multilayer systems for low-temperature bonding in microsystem technology

    NASA Astrophysics Data System (ADS)

    Boettge, Bianca; Braeuer, Joerg; Wiemer, Maik; Petzold, Matthias; Bagdahn, Joerg; Gessner, Thomas

    2010-06-01

    Reactive bonding is a still new low-temperature joining process that is based on reactive nanoscale multilayer systems. The heat required for the bonding process is generated by a self-propagating exothermic reaction within the multilayer system while the adhesive interconnect is supported by solder films. For microsystem applications, the approach is particularly useful if temperature-sensitive components and materials with high differences in coefficient of thermal expansion have to be joined. In this paper, this is successfully demonstrated for bonding a quartz strain gauge onto a stainless steel membrane and an IR-emitter onto a covar socket by using commercially available nickel/aluminum NanoFoils©. The quality of the bond interface of both demonstrators was investigated by scanning electron microscopy and the strength was determined by a tensile test. On the other hand, integrated microsystem applications beyond die attachment require patterned bond structures, e.g. to form bond frames. Thus, alternative materials were additionally considered that can be directly deposited on silicon substrates by magnetron sputtering, such as aluminum/titanium as well as titanium/amorphous silicon (Ti/a-Si) bilayer systems. The properties of these basic multilayer systems and their reaction products were characterized by differential scanning calorimetry and high-resolution electron microscopy. It is shown that specifically the Ti/a-Si system has substantial potential for direct microsystem technology integration provided the remaining open technological issues can be addressed during future research. In general, the results obtained in this study demonstrate the high potential of the reactive bonding process as a new advantageous assembly technology for the fabrication of future microsystems.

  10. Simulations of nanoscale Ni/Al multilayer foils with intermediate Ni2Al3 growth

    NASA Astrophysics Data System (ADS)

    Gunduz, I. E.; Onel, S.; Doumanidis, C. C.; Rebholz, C.; Son, S. F.

    2015-06-01

    Nanoscale multilayers of binary metallic systems, such as nickel/aluminum, exhibit self-propagating exothermic reactions due to the high formation enthalpy of the intermetallic compounds. Most of the previous modeling approaches on the reactions of this system rely on the use of mass diffusion with a phenomenological derived diffusion coefficient representing single-phase (NiAl) growth, coupled with heat transport. We show that the reaction kinetics, temperatures, and thermal front width can be reproduced more satisfactorily with the sequential growth of Ni2Al3 followed by NiAl, utilizing independently obtained interdiffusivities. The computational domain was meshed with a dynamically generated bi-modal grid consisting of fine and coarse zones corresponding to rapid and slower reacting regions to improve computational efficiency. The PDEPE function in MATLAB was used as a basis for an alternating direction scheme. A modified parabolic growth law was employed to model intermetallic growth in the thickness direction. A multiphase enthalpy function was formulated to solve for temperatures after discrete phase growth and transformations at each time step. The results show that the Ni2Al3 formation yields a preheating zone to facilitate the slower growth of NiAl. At bilayer thicknesses lower than 12 nm, the intermixing layer induces oscillating thermal fronts, sharply reducing the average velocities.

  11. Performance of nanoscale metallic multilayer systems under mechanical and thermal loading

    NASA Astrophysics Data System (ADS)

    Economy, David Ross

    Reports of nanoscale metallic multilayers (NMM) performance show a relatively high strength and radiation damage resistance when compared their monolithic components. Hardness of NMMs has been shown to increase with increasing interfacial density (i.e. decreasing layer thickness). This interface density-dependent behavior within NMMs has been shown to deviate from Hall-Petch strengthening, leading to higher measured strengths during normal loading than those predicted by a rule of mixtures. To fully understand why this occurs, other researchers have looked at the influence of the crystal structures of the component layers, orientations, and compositions on deformation processes. Additionally, a limited number of studies have focused on the structural stability and possible performance variation between as-deposited systems and those exposed to mechanical and thermal loading. This dissertation identified how NMM as-deposited structures and performance are altered by mechanical loading (sliding/wear contact) and/or thermal (such as diffusion, relaxation) loading. These objectives were pursued by tracking hardness evolution during sliding wear and after thermal loading to as-deposited stress and mechanical properties. Residual stress progression was also examined during thermal loading and supporting data was collected to detail structural and chemical changes. All of these experimental observations were conducted using Cu/Nb NMMs with 2 nm, 20 nm, or 100 nm thick individual layers deposited with either 1 microm or 10 microm total thicknesses with two geometries (Cu/Nb and Nb/Cu) on (100) Si. Wear boxes were performed on Cu/Nb NMM using a nanoindentation system with a 1 microm conical diamond counterface. After nano-wear deformation, the hardness of the deformed regions significantly rose with respect to as-deposited measurements, which further increased with greater wear loads. Additionally, NMMs with thinner layers showed less volume loss as measured by laser scanning microscopy. Strain hardening exponents for multilayers with thinner layers (2 nm: n ? 0.018 and 20 nm: n ? 0.022 respectively) were less than was determined for 100 nm systems (n ? 0.041). These results suggest that single-dislocation based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This result indicates that both architecture strengthening and strain hardening should be considered if the coating will undergo sliding wear. Furthermore, the hardness of the worn 100 nm system was observed to exceed the as-deposited hardness of the 20 nm, a previously unreported finding, further indicating the interplay between the architecture- and strain-based strengthening mechanisms. Residual stress has been identified as a potential mechanism to cause microstructural instability in NMM architectures. To understand the factors controlling thermal stress evolution for NMMs, the stress in Cu-Nb NMM systems was determined from curvature measurements collected as the sample was cycled from 25°C to 400°C. In addition, the stress within each of the component layers was assessed by using changes in primary peak position from X-ray diffraction (XRD). The thermoelastic slope of NMM systems was shown to not only depend on thermal expansion mismatch and elastic modulus. Analysis showed that layer thickness (interfacial density) affected the magnitude of thermoelastic slope while the layer order was observed to have minimal impact on the stress-response after the initial heating segment. When comparing the monolithic stress responses to those of the Cu-Nb NMM systems, the NMMs show a similar increase in stress magnitude above 200°C to monolithic Nb. This indicates that the Nb layers play a larger role in the development of initial stresses than the Cu layers. Localized stress measurements using in-situ XRD revealed that the stress response of the Cu and Nb layers within the NMM behave similarly to their monolithic counterparts by themselves, rather than the composite stress estimate from curvature measurements. Alth

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

    SciTech Connect

    Wei, Jingsong; Yan, Hui

    2014-08-14

    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 As{sub 2}S{sub 3} 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.

  13. Multilayered graphene in K(a)-band: nanoscale coating for aerospace applications.

    PubMed

    Kuzhir, P; Volynets, N; Maksimenko, S; Kaplas, T; Svirko, Yu

    2013-08-01

    We report on the experimental study of electromagnetic (EM) properties of multilayered graphene in K(a)-band synthesized by catalytic chemical vapor deposition (CVD) process in between nanometrically thin Cu catalyst film and dielectric (SiO2) substrate. The quality of the produced multilayered graphene samples was monitored by Raman spectroscopy. The thickness of graphene films was controlled by atomic force microscopy (AFM) and was found to be a few nanometers (up to 5 nm). We discovered, that the fabricated graphene, being only some thousandth of skin depth, provided remarkably high EM shielding efficiency caused by absorption losses at the level of 35-43% of incident power. Being highly conductive at room temperature, multilayer graphene emerges as a promising material for manufacturing ultrathin microwave coatings to be used in aerospace applications. PMID:23882850

  14. Nanoscale Interfacial Friction and Adhesion on Supported versus Suspended Monolayer and Multilayer Graphene

    E-print Network

    Li, Teng

    , we determine the e ect of tip- subsurface van der Waals interactions on nanoscale friction le of the membrane as a whole, and van der Waals forces between the AFM tip and subsurface layers. We Graphene Zhao Deng,, Nikolai N. Klimov,,§ Santiago D. Solares,, Teng Li,, Hua Xu,, and Rachel J. Cannara

  15. 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

  16. Nanoscale steel-brass multilayer laminates made by cold rolling: Microstructure and tensile properties

    SciTech Connect

    Kavarana, F.H.; Ravichandran, K.S.; Sahay, S.S.

    2000-05-10

    The thrust of this study is to fabricate steel-brass multilayer laminates with layer thicknesses in the nanometer range and to evaluate their mechanical properties. Repeated cold rolling of multilayer stacks was adopted to produce the laminates, because the relative simplicity and the low-cost nature of this process can allow the scaling-up of the technique to the level of commercial-scale production. This work is a continuation of a previous study, in which steel-brass laminates with layer thicknesses in the micrometer range were fabricated for the first time and their tensile properties were evaluated. The present work, however, emphasizes making multilayers with layer thicknesses in the nanometer range and evaluating their mechanical properties. The dependence of strength and ductility on the layer spacing in the nanometer range, is highlighted. It is shown that strength levels comparable to quenched and tempered low alloy steels can be achieved in the laminates by rolling down to the low end of nanometer range. The relevant strengthening mechanisms are also discussed.

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

    SciTech Connect

    Wang, Jian; Hoagland, Richard G; Misra, Amit

    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.

  18. Multiscale modelling and simulation of deformation and strength of nanoscale metallic multilayer systems

    NASA Astrophysics Data System (ADS)

    Abdolrahim, Niaz

    The objective of this research is to investigate the deformation behaviors of two types of NMMs at lower length scales: 1) One dimensional Cu-Ni, Au-Ni nanowires with coherent interfaces and 2) Two dimensional Cu-Nb multilayers with incoherent interfaces. Using molecular dynamics simulations, we investigate the different deformation mechanisms that govern the plastic behavior of the NMMs at different length scales. Based on the fundamental physics of deformation captured by these simulations, we propose models that explain the dependence of strength on layer thickness and identify the regions where the deformation is controlled by either dislocation propagation mechanism or dislocation nucleation mechanism. Chapter 2 investigates the deformation mechanisms of Cu-Ni composite nanowires subjected to uniaxial tensile loading by using MD simulations. The coupled effects of geometry and coherent interface on the twinning and pseudoelastic behavior of nanowires are investigated. It is shown that nanowires exhibit pseudoelastic behaviors when their layer thicknesses are below a critical thickness. We captured similar deformation mechanisms through MD simulations of Au-Ni nano ligaments that are assumed as building blocks of composite Au nanofoams with Ni shells, in chapter 3. Chapter 4 studies the deformation behaviour of Cu-Nb NMMs with incoherent interfaces. Using MD simulations, we investigate the strengthening effect of the weak interfaces interacting with glide dislocations by embedding artificial dislocations inside the layer. In addition, the effects of interfacial discontinuities such as ledges and steps on the strength of the NMMs are investigated. Chapter 5, studies the strengthening effects of the additional second phase particles inside the same Cu-Nb bi-layers. We developed an analytical model to explain the strengthening effect of the precipitates. The theoretical results show a qualitative agreement with the finding of the atomistic simulations. In chapter 6, the operative deformation mechanisms at different length scales for Cu-Nb multilayers under biaxial tensile deformation are determined. We established a unique viscoplastic continuum model able to address the macroscale plastic behaviour of bulk NMMs with layer thickness from few nanometers to hundreds of micrometers. An anisotropic yield function is proposed based on the plastic flow potential obtained from biaxial loading of the NMMs.

  19. Effects of tilt interface boundary on mechanical properties of Cu/Ni nanoscale metallic multilayer composites

    NASA Astrophysics Data System (ADS)

    Yang, Meng; Xu, Jian-Gang; Song, Hai-Yang; Zhang, Yun-Guang

    2015-09-01

    The effect of tilt interfaces and layer thickness of Cu/Ni multilayer nanowires on the deformation mechanism are investigated by molecular dynamics simulations. The results indicate that the plasticity of the sample with a 45° tilt angle is much better than the others. The yield stress is found to decrease with increasing the tilt angle and it reaches its lowest value at 33°. Then as the tilt angle continues to increase, the yield strength increases. Furthermore, the studies show that with the decrease of layer thickness, the yield strength gradually decreases. The study also reveals that these different deformation behaviors are associated with the glide of dislocation. Project supported by the National Natural Science Foundation of China (Grant No. 10902083), the Program for New Century Excellent Talent in University of Ministry of Education of China (Grant No. NCET-12-1046), the Program for New Scientific and Technological Star of Shaanxi Province, China (Grant No. 2012KJXX-39), and the Natural Science Basic Research Plan in Shaanxi Province, China (Grant No. 2014JQ1036).

  20. Characterizing solid-state ignition of runaway chemical reactions in Ni-Al nanoscale multilayers under uniform heating

    NASA Astrophysics Data System (ADS)

    Fritz, Gregory M.; Grzyb, Jessica A.; Knio, Omar M.; Grapes, Michael D.; Weihs, Timothy P.

    2015-10-01

    Nanoscale layers of nickel and aluminum can mix rapidly to produce runaway reactions. While self-propagating high temperature synthesis reactions have been observed for decades, the solid-state ignition of these reactions has been challenging to study. Particularly elusive is characterization of the low-temperature chemical mixing that occurs just prior to the ignition of the runaway reaction. Characterization can be challenging due to inhomogeneous microstructures, uncontrollable heat losses, and the nonuniform distribution of heat throughout the material prior to ignition. To reduce the impact of these variables, we heat multilayered Ni/Al foils in a highly uniform manner and report ignition temperatures as low as 245 °C for heating rates ranging from 2000 °C/s to 50 000 °C/s. Igniting in this way reveals that there are four stages before the reaction is complete: heating to an ignition temperature, low temperature solid-state mixing, a separate high temperature solid-state mixing, and liquid-state mixing. Multiple bilayer spacings, heating rates, and heating times are compared to show that the ignition temperature is a function of the bilayer spacing. A symmetric numerical diffusion model is used to show that there is very little chemical mixing in the first 10 ms of heating but significant mixing after 50 ms. These predictions suggest that ignition temperatures should increase for the slowest heating rates but this trend could not be identified clearly. The modeling was also used to examine the kinetic parameters governing the early stages of solid-state diffusion and suggest that grain boundary diffusion is dominant.

  1. 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.

  2. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    NASA Technical Reports Server (NTRS)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (< 10 microns) single layers to be deposited and multilayer coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  3. Enhanced coercivity in thermally processed (Nd,Dy)(Fe,Co,Nb,B){sub 5.5}/{alpha}-Fe nanoscale multilayer magnets

    SciTech Connect

    Liu, W.; Li, X.Z.; Liu, J.P.; Sun, X.K.; Chen, C.L.; Skomski, R.; Zhang, Z.D.; Sellmyer, D.J.

    2005-05-15

    Structural and magnetic properties of laminated (Nd,Dy)(Fe,Co,Nb,B){sub 5.5}/Fe nanocomposites are investigated. Normally, the addition of the soft phase to the hard phase enhances the remanence but deteriorates the permanent-magnet performance of the material by reducing the coercivity. In the present system, the coercivity increases to 1608 kA/m (20.2 kOe) in thermally processed Nd-Dy-Fe-Co-Nb-B(15 nm)/Fe(4 nm) multilayered nanocomposites, which is higher than that of the single-layer hard-magnetic film. The abnormally high coercivity is achieved by annealing at relatively high temperature, which breaks the laminated structure of the as-deposited multilayer. A likely physical explanation of the enhanced coercivity is the introduction of the domain-wall pinning sites that counteract the inevitable decrease of the nucleation field.

  4. Nanoscale mono- and multi-layer cylinder structures formed by recombinant S-layer proteins of mosquitocidal Bacillus sphaericus C3-41.

    PubMed

    Li, Jia; Yang, Lingling; Hu, Xiaomin; Zheng, Dasheng; Yan, Jianpin; Yuan, Zhiming

    2013-08-01

    The mature surface layer (S-layer) protein SlpC of mosquitocidal Bacillus sphaericus C3-41 comprises amino acids 31-1,176 and could recrystallize in vitro. The N-terminal SLH domain is responsible for binding function. Deletion of this part, S-layer proteins could not bind to the cell wall sacculi. To investigate the self-assembly ability of SlpC from B. sphaericus, nine truncations were constructed and their self-assembly properties were compared with the recombinant mature S-layer protein rSlpC????,???. The results showed that rSbsC????,??? and truncations rSlpC?????,???, rSlpC?????,???, rSlpC????,???, and rSlpC????,??? could assemble into multilayer cylinder structures, while N-terminal truncations rSlpC?????,???, rSlpC?????,???, and rSlpC?????,??? mainly showed monolayer cylinders in recombinant Escherichia coli BL21 (DE3) cells. Growth phase analysis of the self-assembly process revealed that rSlpC?????,??? mainly formed monolayer cylinders in the early stage (0.5 and 1 h induction of expression), but few double-layer or multilayer cylinders were also found with the cells growing, while rSlpC????,??? could formed multilayer cylinders in all the growth stage in the E. coli cells. It is concluded that the deletion of the C-terminal 126 aa or the N-terminal 497 aa did not interfere with the self-assembly process, the fragment (amino acids 278 to 337) is essential for the multilayer cylinder formation in E. coli BL21 (DE3) cells in the early stage and the fragment (amino acids 338 to 497) is related to monolayer cylinder formation. The information is important for further studies on the assembly mechanism of S-layer proteins and forms a basis for further studies concerning surface display and nanobiotechnology. PMID:23306643

  5. Nanoscale Confinement in Single-Layer and Multilayer Supported Polymer Films: Effects on Glass Transition Temperature and Surface Capillary Wave Dynamics near the Glass Transition

    NASA Astrophysics Data System (ADS)

    Torkelson, John

    2014-03-01

    A number of studies have reported major differences in the effects of confinement on the glass transition temperature, Tg, of polymers as determined by (pseudo-)thermodynamic methods and on cooperative segmental dynamics as probed by techniques such as dielectric spectroscopy. While substantial Tg-confinement effects are often observed, the effects on cooperative mobility are often muted or absent. Here, we describe studies employing single-layer films and multilayer films of immiscible polymers in which both Tg and dynamics, related to surface capillary wave relaxation characterized by x-ray photon correlation spectroscopy, are strongly affected by confinement and neighboring polymer layer species. Regarding Tg, we show that a key parameter governing the effect of confinement is polymer fragility - that of the polymer being characterized for Tg in single-layer films and that of the neighboring layer for multilayer films. Similarly, at temperature near Tg, surface capillary wave dynamics of a top layer of a bilayer film can be strongly affected by the neighboring underlayer, with underlayer modulus and confinement itself being important factors governing the dynamics. Both factors are negligible at Tg + 40 K in the case of polystyrene top layers, demonstrating the importance of temperature in tuning the effects of confinement and substrates on dynamics.

  6. 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

  7. 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.

  8. Exothermic reaction waves in multilayer nanofilms

    NASA Astrophysics Data System (ADS)

    Rogachev, A. S.

    2008-01-01

    Experimental and theoretical studies on heterogeneous exothermic reaction waves in multilayer nanofilms are analysed. Mathematical models for the reaction wave propagation are described. The dynamics of phase and structural transformations during heterogeneous reactions in nanoscale systems is considered. Prospects of the studies of reaction waves for the elucidation of the mechanisms of processes in nanoscale systems and for diverse practical applications (in particular, for the development of new welding and soldering techniques) are demonstrated.

  9. Feature Evolution Simulation of I-PVD Copper Films

    NASA Astrophysics Data System (ADS)

    Vyvoda, Michael A.; Abrams, Cameron F.; Graves, David B.

    1998-10-01

    As the semiconductor industry trends toward the use of copper as a primary metallization material, robust process technologies for depositing this material in high aspect structures must be developed. One technique that has shown promise in accomplishing this task is ionized physical vapor deposition (I-PVD),(P.F. Cheng et al.), J. Vac. Sci. Technol. B 13, 203 (1995). which can be used to perform the entire fill or provide a seed layer for subsequent copper electroplating. A key need in designing I-PVD processes is controlling the degree of sidewall copper coverage during seed layer deposition and preventing pinch-off during total fill. We have developed a numerical simulation of copper film evolution during I-PVD processing that addresses these issues. The simulation uses as inputs distribution functions of plasma ions (Ar^+ and Cu^+) and neutrals (Cu) as well as reflection and sputtering distributions of energetic species impacting copper surfaces.(C.F. Abrams, unpublished.) This methodology allows for the proper tracking of reflected and sputtered material as it redeposits elsewhere within the feature. Independent variables include ion-ion and ion-neutral flux ratios as well as wafer bias voltage. We show that for a given initial feature aspect ratio, optimal conditions for achieving high film conformality and pinch-free fill can be determined by proper adjustment of these independent variables.

  10. 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

  11. 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

  12. Nanoscale Simulations Research Profile

    E-print Network

    Daraio, Chiara

    .nanosim.mat.ethz.ch The Nanoscale Simulations group is part of the Com- petence Center for Materials and Processes (MaP). MaP bringsNanoscale Simulations Research Profile Our research focus is to enable modeling at the nanoscale. To do so, we develop a new generation of simulation software that extends the length, time and accuracy

  13. 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.

  14. 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

  15. 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.

  16. A review-application of physical vapor deposition (PVD) and related methods in the textile industry

    NASA Astrophysics Data System (ADS)

    Shahidi, Sheila; Moazzenchi, Bahareh; Ghoranneviss, Mahmood

    2015-09-01

    Physical vapor deposition (PVD) is a coating process in which thin films are deposited by the condensation of a vaporized form of the desired film material onto the substrate. The PVD process is carried out in a vacuum. PVD processes include different types, such as: cathode arc deposition, electron beam physical vapor deposition, evaporative deposition, sputtering, ion plating and enhanced sputtering. In the PVD method, the solid coating material is evaporated by heat or by bombardment with ions (sputtering). At the same time, a reactive gas is also introduced; it forms a compound with the metal vapor and is deposited on the substrate as a thin film with highly adherent coating. Such coatings are used in a wide range of applications such as aerospace, automotive, surgical, medical, dyes and molds for all manner of material processing, cutting tools, firearms, optics, thin films and textiles. The objective of this work is to give a comprehensive description and review of the science and technology related to physical vapor deposition with particular emphasis on their potential use in the textile industry. Physical vapor deposition has opened up new possibilities in the modification of textile materials and is an exciting prospect for usage in textile design and technical textiles. The basic principle of PVD is explained and the major applications, particularly sputter coatings in the modification and functionalization of textiles, are introduced in this research.

  17. 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.

  18. Structural characterization and high throughput screening of inhibitors of PvdQ, an NTN hydrolase involved in pyoverdine synthesis

    PubMed Central

    Drake, Eric J.; Gulick, Andrew M.

    2011-01-01

    The human pathogen Pseudomonas aeruginosa produces a variety of virulence factors including pyoverdine, a non-ribosomally produced peptide siderophore. The maturation pathway of the pyoverdine peptide is complex and provides a unique target for inhibition. Within the pyoverdine biosynthetic cluster is a periplasmic hydrolase, PvdQ, that is required for pyoverdine production. However, the precise role of PvdQ in the maturation pathway has not been biochemically characterized. We demonstrate herein that the initial module of the nonribosomal peptide synthetase PvdL adds a myristate moiety to the pyoverdine precursor. We extracted this acylated precursor, called PVDIq, from a pvdQ mutant strain and show that the PvdQ enzyme removes the fatty acid catalyzing one of the final steps in pyoverdine maturation. Incubation of PVDIq with crystals of PvdQ allowed us to capture the acylated enzyme and confirm through structural studies the chemical composition of the incorporated acyl chain. Finally, because inhibition of siderophore synthesis has been identified as a potential antibiotic strategy, we developed a high throughput screening assay and tested a small chemical library for compounds that inhibit PvdQ activity. Two compounds that block PvdQ have been identified and their binding within the fatty acid binding pocket structurally characterized. PMID:21892836

  19. PvdP Is a Tyrosinase That Drives Maturation of the Pyoverdine Chromophore in Pseudomonas aeruginosa

    PubMed Central

    Nadal-Jimenez, Pol; Koch, Gudrun; Reis, Carlos R.; Muntendam, Remco; Raj, Hans; Jeronimus-Stratingh, C. Margot; Cool, Robbert H.

    2014-01-01

    The iron binding siderophore pyoverdine constitutes a major adaptive factor contributing to both virulence and survival in fluorescent pseudomonads. For decades, pyoverdine production has allowed the identification and classification of fluorescent and nonfluorescent pseudomonads. Here, we demonstrate that PvdP, a periplasmic enzyme of previously unknown function, is a tyrosinase required for the maturation of the pyoverdine chromophore in Pseudomonas aeruginosa. PvdP converts the nonfluorescent ferribactin, containing two iron binding groups, into a fluorescent pyoverdine, forming a strong hexadentate complex with ferrous iron, by three consecutive oxidation steps. PvdP represents the first characterized member of a small family of tyrosinases present in fluorescent pseudomonads that are required for siderophore maturation and are capable of acting on large peptidic substrates. PMID:24816606

  20. 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.

  1. 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...

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

    SciTech Connect

    Zbib, Hussein M; Bahr, David F

    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.

  3. Pyoverdine and beyond: PvdS dependent gene regulation in Pseudomonas syringae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The extracytoplasmic function (ECF) sigma factor PvdS regulates the expression of genes in Pseudomonas aeruginosa encoding virulence factors and the biosynthesis and transport of pyoverdine, a siderophore involved in iron acquisition. The production of pyoverdine is a distinctive trait of the fluor...

  4. PvD1 defensin, a plant antimicrobial peptide with inhibitory activity against Leishmania amazonensis

    PubMed Central

    do Nascimento, Viviane V.; Mello, Érica de O.; Carvalho, Laís P.; de Melo, Edésio J.T.; Carvalho, André de O.; Fernandes, Katia V.S.; Gomes, Valdirene M.

    2015-01-01

    Plant defensins are small cysteine-rich peptides and exhibit antimicrobial activity against a variety of both plant and human pathogens. Despite the broad inhibitory activity that plant defensins exhibit against different micro-organisms, little is known about their activity against protozoa. In a previous study, we isolated a plant defensin named PvD1 from Phaseolus vulgaris (cv. Pérola) seeds, which was seen to be deleterious against different yeast cells and filamentous fungi. It exerted its effects by causing an increase in the endogenous production of ROS (reactive oxygen species) and NO (nitric oxide), plasma membrane permeabilization and the inhibition of medium acidification. In the present study, we investigated whether PvD1 could act against the protozoan Leishmania amazonensis. Our results show that, besides inhibiting the proliferation of L. amazonensis promastigotes, the PvD1 defensin was able to cause cytoplasmic fragmentation, formation of multiple cytoplasmic vacuoles and membrane permeabilization in the cells of this organism. Furthermore, we show, for the first time, that PvD1 defensin was located within the L. amazonensis cells, suggesting the existence of a possible intracellular target. PMID:26285803

  5. PvD1 defensin, a plant antimicrobial peptide with inhibitory activity against Leishmania amazonensis.

    PubMed

    do Nascimento, Viviane V; Mello, Érica de O; Carvalho, Laís P; de Melo, Edésio J T; Carvalho, André de O; Fernandes, Katia V S; Gomes, Valdirene M

    2015-01-01

    Plant defensins are small cysteine-rich peptides and exhibit antimicrobial activity against a variety of both plant and human pathogens. Despite the broad inhibitory activity that plant defensins exhibit against different micro-organisms, little is known about their activity against protozoa. In a previous study, we isolated a plant defensin named PvD1 from Phaseolus vulgaris (cv. Pérola) seeds, which was seen to be deleterious against different yeast cells and filamentous fungi. It exerted its effects by causing an increase in the endogenous production of ROS (reactive oxygen species) and NO (nitric oxide), plasma membrane permeabilization and the inhibition of medium acidification. In the present study, we investigated whether PvD1 could act against the protozoan Leishmania amazonensis. Our results show that, besides inhibiting the proliferation of L. amazonensis promastigotes, the PvD1 defensin was able to cause cytoplasmic fragmentation, formation of multiple cytoplasmic vacuoles and membrane permeabilization in the cells of this organism. Furthermore, we show, for the first time, that PvD1 defensin was located within the L. amazonensis cells, suggesting the existence of a possible intracellular target. PMID:26285803

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Friction at the nanoscale

    SciTech Connect

    Family, F.; Hentschel, H.G.E.; Braiman, Y.

    2000-04-27

    Dissipation mechanisms at the nanoscale are influenced by finite size effects that may significantly affect the frictional response of sliding objects. In particular, locking of temporal and spatial dynamics may introduce several distinct modes of motion leading to friction selection. Here, the authors discuss such nonlinear mechanisms leading to stick-slip dynamics at the atomic scale.

  11. The effect of PVD coatings on the wear behaviour of magnesium alloys

    SciTech Connect

    Altun, Hikmet Sen, Sadri

    2007-10-15

    In this study, AlN/TiN was coated on magnesium alloys using physical vapour deposition (PVD) technique of DC magnetron sputtering, and the influence of the coating on the wear behaviour of the alloys was examined. A physical vapour deposition system for coating processes, a reciprocating wear system for wear tests, a universal hardness equipment for hardness measurement, a X-ray diffractometer (XRD) for compositional analysis of the coating, and a scanning electron microscopy (SEM) for surface examinations were used. It was determined that the wear resistance of the magnesium alloys can be increased by PVD coatings. However, small structural defects which could arise from the coating process or substrate were observed in the coating layers.

  12. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1992-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the ransition temperature.

  13. Extreme ultraviolet multilayer reflectors

    SciTech Connect

    Scott, M.L.; Arendt, P.N.; Cameron, B.J.; Newman, B.E.; Windt, D.; Cash, W.

    1986-01-01

    We have investigated the design, fabrication, and reflectance measurements of a multilayer silver/silicon reflector for use at 58.4 nm. Our results indicate that reflectors in the extreme ultraviolet do not perform as well as predicted due to the presence of surface oxides and other surface contamination layers. In addition, we have found that the correct optical constants for silver have now been published. We find also that these multilayer coatings can be utilized as reflective polarizers in the EUV with an extinction ratio of 75:1 and a throughput of 28% for the s-polarized component of the beam.

  14. 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...

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

    SciTech Connect

    Polyakov, M. N.; Hodge, A. M.; Courtois-Manara, E.; Wang, D.; Kuebel, C.; Chakravadhanula, K.; Helmholtz Institute Ulm, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen

    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.

  16. 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.

  17. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1991-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependant FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers if contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work. 2 figs.

  18. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1990-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project period the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work.

  19. DNA in Nanoscale Electronics

    NASA Astrophysics Data System (ADS)

    Slinker, Jason

    2012-10-01

    DNA, the quintessential molecule of life, possesses a number of attractive properties for use in nanoscale circuits. Charge transport (CT) through DNA itself is of both fundamental and practical interest. Fundamentally, DNA has a unique configuration of ?-stacked bases in a well ordered, double helical structure. Given its unparalleled importance to life processes and its arrangement of conjugated subunits, DNA has been a compelling target of conductivity studies. In addition, further understanding of DNA CT will elucidate the biological implications of this process and advance its use in sensing technologies. We have investigated the fundamentals of DNA CT by measuring the electrochemistry of DNA monolayers under biologically-relevant conditions. We have uncovered both fundamental kinetic parameters to distinguish between competing models of operation as well as the practical implications of DNA CT for sensing. Furthermore, we are leveraging our studies of DNA conductivity for the manufacture of nanoscale circuits. We are investigating the electrical properties and self-assembly of DNA nanowires containing artificial base pair surrogates, which can be prepared through low cost and high throughput automated DNA synthesis. This unique and economically viable approach will establish a new paradigm for the scalable manufacture of nanoscale semiconductor devices.

  20. Stresses in multilayered cables

    SciTech Connect

    Costello, G.A.

    1983-01-01

    A theory is presented which will predict the stresses in a multilayered cable, subjected to axial, bending and torsional loads. In the axial case, the axial force and axial twisting moment are represented as linear combinations of the axial strain and the rotational strain. An analysis is also made of a cable subjected to axial loads and wrapped around a drum. The analysis involves a superposition of the stresses caused by the axial loads and the bending loads.

  1. Nanotribology and Nanoscale Friction

    SciTech Connect

    Guo, Yi; Qu, Zhihua; Braiman, Yehuda; Zhang, Zhenyu; Barhen, Jacob

    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.

  2. Box 6: Nanoscale Defects

    NASA Astrophysics Data System (ADS)

    Alves, Eduardo; Breese, Mark

    Defects affect virtually all properties of crystalline materials, and their role is magnified in nanoscale structures. In this box we describe the different type of defects with particular emphasis on point and linear defects. Above zero Kelvin all real materials have a defect population within their structure, which affects either their crystalline, electronic or optical properties. It is common to attribute a negative connotation to the presence of defects. However, a perfect silicon crystal or any other defect-free semiconductor would have a limited functionality and might even be useless.

  3. Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

    SciTech Connect

    Chen, C. Q.; Pei, Y. T.; Shaha, K. P.; De Hosson, J. Th. M.

    2009-06-01

    This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens of nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.

  4. Rational design of a transition state analogue with picomolar affinity for Pseudomonas aeruginosa PvdQ, a siderophore biosynthetic enzyme.

    PubMed

    Clevenger, Kenneth D; Wu, Rui; Er, Joyce A V; Liu, Dali; Fast, Walter

    2013-10-18

    The Pseudomonas aeruginosa enzyme PvdQ can process different substrates involved in quorum-sensing or in siderophore biosynthesis. Substrate selectivity was evaluated using steady-state kinetic constants for hydrolysis of N-acyl-homoserine lactones (HSLs) and p-nitrophenyl fatty acid esters. PvdQ prefers substrates with alkyl chains between 12 and 14 carbons long that do not bear a 3-oxo substitution and is revealed here to have a relatively high specificity constant for selected N-acyl-HSLs (kcat/KM = 10(5) to 10(6) M(-1) s(-1)). However, endogenous P. aeruginosa N-acyl-HSLs are ?100-fold disfavored, supporting the conclusion that PvdQ was not primarily evolved to regulate endogenous quorum-sensing. PvdQ plays an essential biosynthetic role for the siderophore pyoverdine, on which P. aeruginosa depends for growth in iron-limited environments. A series of alkylboronate inhibitors was found to be reversible, competitive, and extremely potent (Ki ? 190 pM). A 1.8 Å X-ray structure shows that 1-tridecylboronic acid forms a monocovalent bond with the N-terminal ?-chain Ser residue in the PvdQ heterodimer, mimicking a reaction transition state. This boronic acid inhibits growth of P. aeruginosa in iron-limited media, reproducing the phenotype of a genetic pvdQ disruption, although co-administration of an efflux pump inhibitor is required to maintain growth inhibition. These findings support the strategy of designing boron-based inhibitors of siderophore biosynthetic enzymes to control P. aeruginosa infections. PMID:23883096

  5. 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.

  6. Investigation of Ti and Cr based PVD coatings deposited onto HSS Co 5 twist drills

    NASA Astrophysics Data System (ADS)

    Kottfer, D.; Ferdinandy, M.; Kaczmarek, L.; Ma?ková, I.; Be?o, J.

    2013-10-01

    This study investigates the properties and cutting performance of thin TiN, TiAlN, CrAlN and KTRN coatings applied by two PVD techniques. PVD techniques ARC and SARC (it denotes the arc method by STATON company, Slovakia - deposited with smaller microdrops) were used for the deposition of thin coatings onto twist drills prepared by powder metallurgy. Conventional types of coatings - monolayers TiN, TiAlN, CrAlN and advanced type of the coating - monolayer KTRN (denoted by producer - STATON company Slovakia) on the basis of Ti and Al deposited with smaller drops on the surface - were analyzed by standard techniques for surface status and quality assessment - coating thickness, chemical composition by EDX analysis, adhesion, hardness, roughness and tribological properties at room temperature. Durability testing of the twist drills was carried out according to the standard ISO 3685-1999. CrAlN and TiAlN monolayers achieved lower roughness when compared to monolayer TiN and advanced type of the monolayer KTRN. TiAlN and KTRN coatings which leads to the achievement of higher hardness and better coating quality. The microhardness values were ?35 GPa. The results showed two to four times lower flank wear VB of the evaluated drills with TiAlN and KTRN coatings in comparison with equivalent uncoated material of the drill. The deposited TiAlN and KTRN coatings contributed to the improvement of their durability.

  7. 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.

  8. Process for manufacturing multilayer capacitors

    DOEpatents

    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.

  9. 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.

  10. Nanoscale data storage

    E-print Network

    J. C. Li

    2007-01-29

    The object of this article is to review the development of ultrahigh-density, nanoscale data storage, i.e., nanostorage. As a fundamentally new type of storage system, the recording mechanisms of nanostorage may be completely different to those of the traditional devices. Currently, two types of molecules are being studied for potential application in nanostorage. One is molecular electronic elements including molecular wires, rectifiers, switches, and transistors. The other approach employs nanostructured materials such as nanotubes, nanowires, and nanoparticles. The challenges for nanostorage are not only the materials, ultrahigh data-densities, fabrication-costs, device operating temperatures and large-scale integration, but also the development of the physical principles and models. There are already some breakthroughs obtained, but it is still unclear what kind of nanostorage systems can ultimately replace the current silicon based transistors. A promising candidate may be a molecular-nanostructure hybrid device with sub-5 nm dimensions.

  11. A Nanoscale Tale

    NASA Astrophysics Data System (ADS)

    Serrano, Elba

    2008-10-01

    Experimentalists constantly seek to overcome technical limitations. This is especially true in the world of biophysics, where the drive to study molecular targets such as ion channels, a type of membrane transport protein, has resulted in methodological breakthroughs that have merited the Nobel Prize (Hodgkin and Huxley, 1963; Neher and Sakmann, 1991). In this presentation I will explain how nanoscale phenomena that are essential for sensory perception underlie the ability of dancers, gymnasts, and musicians to excel at their artistic endeavors. I will describe how our investigations of sensory mechanotransduction and the quest for improved signal amplification inspired a scientific journey that has culminated in an exciting new line of collaborative NIH-funded research with nanomaterials (quantum dots). I will conclude with a general discussion of how training in physics offers an ideal foundation for interdisciplinary research in health related fields, such as those that deal with neuroscience and disorders of the nervous system.

  12. Nanoscale magnetic resonance imaging

    PubMed Central

    Degen, C. L.; Poggio, M.; Mamin, H. J.; Rettner, C. T.; Rugar, D.

    2009-01-01

    We have combined ultrasensitive magnetic resonance force microscopy (MRFM) with 3D image reconstruction to achieve magnetic resonance imaging (MRI) with resolution <10 nm. The image reconstruction converts measured magnetic force data into a 3D map of nuclear spin density, taking advantage of the unique characteristics of the “resonant slice” that is projected outward from a nanoscale magnetic tip. The basic principles are demonstrated by imaging the 1H spin density within individual tobacco mosaic virus particles sitting on a nanometer-thick layer of adsorbed hydrocarbons. This result, which represents a 100 million-fold improvement in volume resolution over conventional MRI, demonstrates the potential of MRFM as a tool for 3D, elementally selective imaging on the nanometer scale. PMID:19139397

  13. 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.

  14. 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.

  15. Investigation of failure mechanism of thermal barrier coatings (TBCs) deposited by EB-PVD technique

    NASA Astrophysics Data System (ADS)

    Shahid, M. R.; Abbas, Musharaf

    2013-06-01

    Failure mechanism of thermal barrier coatings (TBCs) prepared by electron beam physical vapor deposition (EB-PVD) technique owing to formation of micro cracks was investigated. The TBCs were deposited on the Ni-based super alloy IN-100 and the micro cracks were observed within the top ceramic coat of thermally cycled TBCs at 1050°C. It was observed that these cracks propagate in the ceramic coat in the direction normal to interface while no cracks were observed in the bond coat. SEM/EDS studies revealed that some non-uniform oxides were formed on the interface between ceramic top and metallic bond coat just below the cracks. Study proposed that the cracks were initiated due to stress owing to big difference in Pilling-Bed worth ratio of non-uniform oxides as well as thermal stress, which caused the formation of cracks in top ceramic coat leading to failure of TBCs

  16. Computational modelling of constrained sintering in EB-PVD thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Cocks, A. C. F.

    2013-09-01

    A micromechanical model is developed to simulate the evolution of microstructure during in-service sintering and eventual inter-columnar cracking in coatings made using electron beam vapour deposition (EB-PVD) route. The coating is idealized with a discrete distribution of axisymmetric asperities across interfaces between columnar grains. The model assumes that inter-columnar sintering is driven by changes in interface free energy of columns and the potential energy of the applied stress. Much faster diffusion that occurs over the free surfaces of the asperities is neglected. It is further assumed that the rate of sintering of the contacting asperities is determined by diffusion along the interface between the contacting asperities. Time evolution of contact modulus of the coating is accounted for as a function of sintering strain. The developed macroscopic constitutive model is employed to evaluate the sensitivity of the sintering response to imperfections and examine the conditions under which inter-columnar cracks can develop within the coating.

  17. Physicochemical studies of PVdF-HFP-based polymer-ionic liquid composite electrolytes

    NASA Astrophysics Data System (ADS)

    Lalia, Boor Singh; Yamada, K.; Hundal, M. S.; Park, Jin-Soo; Park, Gu-Gon; Lee, Won-Yong; Kim, Chang-Soo; Sekhon, S. S.

    2009-08-01

    Polymer-ionic liquid composite electrolytes based on poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) and room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium hexafluorophosphate (DMOImPF6) have been synthesized and studied. The addition of dimethylacetamide (DMA) and propylene carbonate (PC), both with high dielectric constant and low viscosity, to polymer electrolytes has been found to result in an enhancement of conductivity by one order of magnitude. Composite polymer electrolytes containing ionic liquid have been found to be thermally stable upto 300°C. Motional narrowing observed in the variation of line width of 1H and 19F NMR peaks with temperature suggests that both cations and anions are mobile in these electrolytes.

  18. Multilayer optical dielectric coating

    DOEpatents

    Emmett, John L. (Pleasanton, CA)

    1990-01-01

    A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

  19. A multilayer sonic film

    NASA Astrophysics Data System (ADS)

    Munteanu, L.; Chiroiu, V.; Sireteanu, T.; Dumitriu, D.

    2015-10-01

    A non-periodic multilayer film was analyzed to show that, despite its non-periodicity, the film exhibits full band-gaps and localized modes at its interfaces, as well as in the sonic composites. The film consists of alternating layers of two different materials that follow a triadic Cantor sequence. The Cantor structure shows extremely low thresholds for subharmonic generation of ultrasonic waves, compared with homogeneous and periodic structures. The coupling between the extended-mode (phonon) and the localized-mode (fracton) vibration regimes explains the generation of full band-gaps, for which there are no propagating Lamb waves. The large enhancement of the nonlinear interaction results from a more favorable frequency and spatial matching of coupled modes. A full band-gap that excludes Love waves is also analyzed.

  20. Multilayer graphene condenser microphone

    NASA Astrophysics Data System (ADS)

    Todorovi?, Dejan; Matkovi?, Aleksandar; Mili?evi?, Marijana; Jovanovi?, Djordje; Gaji?, Radoš; Salom, Iva; Spasenovi?, Marko

    2015-12-01

    Vibrating membranes are the cornerstone of acoustic technology, forming the backbone of modern loudspeakers and microphones. Acoustic performance of a condenser microphone is derived mainly from the membrane’s size, surface mass and achievable static tension. The widely studied and available nickel has been a dominant membrane material for professional microphones for several decades. In this paper we introduce multilayer graphene as a membrane material for condenser microphones. The graphene device outperforms a high end commercial nickel-based microphone over a significant part of the audio spectrum, with a larger than 10 dB enhancement of sensitivity. Our experimental results are supported with numerical simulations, which also show that a 300 layer thick graphene membrane under maximum tension would offer excellent extension of the frequency range, up to 1 MHz.

  1. Multilayered folding with voids

    E-print Network

    Timothy Dodwell; Giles Hunt; Mark Peletier; Chris Budd

    2011-05-24

    In the deformation of layered materials such as geological strata, or stacks of paper, mechanical properties compete with the geometry of layering. Smooth, rounded corners lead to voids between the layers, while close packing of the layers results in geometrically-induced curvature singularities. When voids are penalized by external pressure, the system is forced to trade off these competing effects, leading to sometimes striking periodic patterns. In this paper we construct a simple model of geometrically nonlinear multi-layered structures under axial loading and pressure confinement, with non-interpenetration conditions separating the layers. Energy minimizers are characterized as solutions of a set of fourth-order nonlinear differential equations with contact-force Lagrange multipliers, or equivalently of a fourth-order free-boundary problem. We numerically investigate the solutions of this free boundary problem, and compare them with the periodic solutions observed experimentally.

  2. Integrated Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Dye, Scott

    2009-01-01

    Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

  3. Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Schäfer, C.; Bobzin, K.; Bagcivan, N.; Brögelmann, T.; Theiß, S.; Münstermann, T.; Steger, M.

    2015-05-01

    Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt. In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.

  4. Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

    SciTech Connect

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Schäfer, C.; Bobzin, K.; Bagcivan, N.; Brögelmann, T.; Theiß, S.; Münstermann, T.; Steger, M.

    2015-05-22

    Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt. In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.

  5. Diffusion bonding of CMSX-4 to UDIMET 720 using PVD-coated interfaces and HIP

    SciTech Connect

    Larker, R.; Ockborn, J.; Selling, B.

    1999-07-01

    There is an increasing interest in development of manufacturing methods for Dual Property BLISKs (BLaded dISKs), consisting of creep resistant airfoils and fatigue resistant disks bonded together by a durable joint. Optimum heat treatments are, however, very different for creep resistant single crystal CMSX-4 and fatigue resistant polycrystalline Udimet 720 selected in this study, but fortunately the first aging treatment for CMSX-4 (1140 C, 2-6h, AC) is similar to the partial solution treatment of U 720 HS2 (1115 C, 4h, OQ). Based on this, diffusion bonding was performed by HIP at 1120 C and 200 MPa argon pressure for 4 h, followed by cooling to 400 C. Subsequently, a shortened Udimet 720 HS2 two-step aging treatment was adopted by heating to 650 C for 6 h followed by cooling to 400 C, heating to 760 C for 2 h, and finally cooling to R.T. under remaining HIP pressure. Plasma etching followed by thin (80 nm) PVD coating with either nickel or titanium were used to clean and protect the polished surfaces before joining. The selection of coatings was governed by the possibility to reduce oxidized nickel by flushing with hydrogen at 330 C during evacuation of the HIP capsules, and by the large solubility of oxygen in titanium. Hot tensile testing was performed at 750 C on both joined and reference materials subjected to the modified heat treatment. Initially solution treated Udimet 720 and CMSX-4 comprised the reference materials. The testing showed that joints with Ni-PV coatings were almost as strong as Udimet 720 (although with very limited elongation), while the joints with Ti-PVD coatings were weaker.

  6. Nanoscale Electrostatics in Mitosis

    NASA Astrophysics Data System (ADS)

    Gagliardi, L. John; West, Patrick Michael

    2001-04-01

    Primitive biological cells had to divide with very little biology. This work simulates a physicochemical mechanism, based upon nanoscale electrostatics, which explains the anaphase A poleward motion of chromosomes. In the cytoplasmic medium that exists in biological cells, electrostatic fields are subject to strong attenuation by Debye screening, and therefore decrease rapidly over a distance equal to several Debye lengths. However, the existence of microtubules within cells changes the situation completely. Microtubule dimer subunits are electric dipolar structures, and can act as intermediaries that extend the reach of the electrostatic interaction over cellular distances. Experimental studies have shown that intracellular pH rises to a peak at mitosis, and decreases through cytokinesis. This result, in conjunction with the electric dipole nature of microtubule subunits and the Debye screened electrostatic force is sufficient to explain and unify the basic events during mitosis and cytokinesis: (1) assembly of asters, (2) motion of the asters to poles, (3) poleward motion of chromosomes (anaphase A), (4) cell elongation, and (5) cytokinesis. This paper will focus on a simulation of the dynamics if anaphase A motion based on this comprehensive model. The physicochemical mechanisms utilized by primitive cells could provide important clues regarding our understanding of cell division in modern eukaryotic cells.

  7. Multilayered Magnetic Gelatin Membrane Scaffolds.

    PubMed

    Samal, Sangram K; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-10-21

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial-magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  8. Multilayer thermal barrier coating systems

    DOEpatents

    Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

    2000-01-01

    The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

  9. 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

  10. n-Alkylboronic acid inhibitors reveal determinants of ligand specificity in the quorum-quenching and siderophore biosynthetic enzyme PvdQ.

    PubMed

    Clevenger, Kenneth D; Wu, Rui; Liu, Dali; Fast, Walter

    2014-10-28

    The enzyme PvdQ (E.C. 3.5.1.97) from Pseudomonas aeruginosa is an N-terminal nucleophile hydrolase that catalyzes the removal of an N-myristyl substituent from a biosynthetic precursor of the iron-chelating siderophore pyoverdine. Inhibitors of pyoverdine biosynthesis are potential antibiotics since iron is essential for growth and scarce in most infections. PvdQ also catalyzes hydrolytic amide bond cleavage of selected N-acyl-l-homoserine lactone quorum-sensing signals used by some Gram-negative pathogens to coordinate the transcription of virulence factors. The resulting quorum-quenching activity of PvdQ has potential applications in antivirulence therapies. To inform both inhibitor design and enzyme engineering efforts, a series of n-alkylboronic acid inhibitors of PvdQ was characterized to reveal determinants of ligand selectivity. A simple homologation series results in compounds with Ki values that span from 4.7 mM to 190 pM, with a dependence of ?Gbind values on chain length of -1.0 kcal/mol/CH2. X-ray crystal structures are determined for the PvdQ complexes with 1-ethyl-, 1-butyl-, 1-hexyl-, and 1-octylboronic acids at 1.6, 1.8, 2.0, and 2.1 Å resolution, respectively. The 1-hexyl- and 1-octylboronic acids form tetrahedral adducts with the active-site N-terminal Ser217 in the ?-subunit of PvdQ, and the n-alkyl substituents are bound in the acyl-group binding site. The 1-ethyl- and 1-butylboronic acids also form adducts with Ser217 but instead form trigonal planar adducts and extend their n-alkyl substituents into an alternative binding site. These results are interpreted to propose a ligand discrimination model for PvdQ that informs the development of PvdQ-related tools and therapeutics. PMID:25290020

  11. Nanoscale Surface Topography to Guide Bone Growth

    E-print Network

    Nanoscale Surface Topography to Guide Bone Growth P R O J E C T L E A D E R : Jirun Sun (American T S Designed and fabricated devices with nanoscale surface topography. Controlled cell alignment by varying

  12. 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...

  13. Quantitative nanoscale characterisation by electron microscopy

    E-print Network

    Dunin-Borkowski, Rafal E.

    Quantitative nanoscale characterisation by electron microscopy Martin Hÿtch* -- Pascale Bayle of nanoscale devices: strain mapping by high-resolution electron microscopy (HREM), elemental mapping by energy filtered microscopy (EFTEM), and measurements of magnetic and electric fields by electron holography. KEY

  14. Quantitative Tomography of Organic Photovoltaic Blends at the Nanoscale.

    PubMed

    Pfannmöller, M; Heidari, H; Nanson, L; Lozman, O R; Chrapa, M; Offermans, T; Nisato, G; Bals, S

    2015-10-14

    The success of semiconducting organic materials has enabled green technologies for electronics, lighting, and photovoltaics. However, when blended together, these materials have also raised novel fundamental questions with respect to electronic, optical, and thermodynamic properties. This is particularly important for organic photovoltaic cells based on the bulk heterojunction. Here, the distribution of nanoscale domains plays a crucial role depending on the specific device structure. Hence, correlation of the aforementioned properties requires 3D nanoscale imaging of materials domains, which are embedded in a multilayer device. Such visualization has so far been elusive due to lack of contrast, insufficient signal, or resolution limits. In this Letter, we introduce spectral scanning transmission electron tomography for reconstruction of entire volume plasmon spectra from rod-shaped specimens. We provide 3D structural correlations and compositional mapping at a resolution of approximately 7 nm within advanced organic photovoltaic tandem cells. Novel insights that are obtained from quantitative 3D analyses reveal that efficiency loss upon thermal annealing can be attributed to subtle, fundamental blend properties. These results are invaluable in guiding the design and optimization of future devices in plastic electronics applications and provide an empirical basis for modeling and simulation of organic solar cells. PMID:26390367

  15. 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.

  16. Thermoelectric effects in nanoscale junctions.

    PubMed

    Dubi, Yonatan; Di Ventra, Massimiliano

    2009-01-01

    Despite its intrinsic nonequilibrium origin, thermoelectricity in nanoscale systems is usually described within a static scattering approach which disregards the dynamical interaction with the thermal baths that maintain energy flow. Using the theory of open quantum systems, we show instead that unexpected properties, such as a resonant structure and large sign sensitivity, emerge if the nonequilibrium nature of this problem is considered. Our approach also allows us to define and study a local temperature, which shows hot spots and oscillations along the system according to the coupling of the latter to the electrodes. This demonstrates that Fourier's lawa paradigm of statistical mechanicsis generally violated in nanoscale junctions. PMID:19072125

  17. 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.

  18. 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.

  19. The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

    SciTech Connect

    Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D.; Nagaraj, B.A.

    1996-05-01

    Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

  20. Blending effect of poly (ethyl methacrylate) on lithium bis(perfluoroethanesulfonyl) imide-ferroceramic PVdF-HFP composite

    NASA Astrophysics Data System (ADS)

    Vickraman, P.; Jayaraman, R.; Purushothaman, K.

    2013-06-01

    PEMA as a supportive host matrix is physically blended in five different proportions with PVdF-HFP based system containing LiBETI as a electrolyte, EC / DMC mixture in 1:1 v/v ratio as a plasticizer and BaTiO3 as a filler for improving ionic conductivity is attempted. The A.C impedance, DSC, and FTIR studies are carried out. The ionic conductivity measurements on these Polymer Blend Nano Composites(PBNC) showed that blending improved ionic conductivity, and enhancement in magnitude is observed for 22.5% PEMA blended PVdF-HFP (7.5 wt%) system with 7.5% BaTiO3. The DSC showed PEMA interaction with PVDF causing reorientation of VDF crystals and resulting conformational changes showed variations in melting endotherms, are observed. FTIR studies identified PEMA interaction with plasticizer and PVdF-HFP through the change in the C-F stretching and C=O Carbonyl bond.

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

    SciTech Connect

    Zhernenkov, Mikhail E-mail: gills@bnl.gov; Gill, Simerjeet E-mail: gills@bnl.gov; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Ecker, Lynne; Baldwin, J. Kevin; Misra, Amit; Demkowicz, M. J.

    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.

  2. The use of low-energy SIMS (LE-SIMS) for nanoscale fuel cell material development

    SciTech Connect

    Morris, R. J. H.; Fearn, Sarah; Perkins, James; Kilner, John; Dowsett, M. G.; Biegalski, Michael D; Rouleau, Christopher M

    2011-01-01

    Low-energy secondary ion mass spectrometry has been used to investigate the matrix structure and interface attributes of a novel Ce0.85Sm0.15O2/CeO2 multilayer fuel cell material. Nanoscale oxide systems have shown enhanced ionic conductivities when produced to form highly oriented epitaxial structures. The Sm-doped CeO2 material system is of particular interest for fuel cell technology because of its inherently high ionic conductivity at low operating temperatures (600-800 C). For this study, a nanometer-scale Ce0.85Sm0.15O2/CeO2 multilayer was grown by pulsed laser deposition. The sample was annealed at 700 C in an oxygen ambience. High-resolution, low-energy depth profiling using Cs revealed some diffusion of the multilayer structure after annealing, along with a possible volume change for the Sm-doped layers. Changes in layer volume will lead to an increase in the mechanical strain and may cause the material to crack. The findings presented here suggest that the Ce0.85Sm0.15O2/CeO2 multilayer structure in its current form may not possess the level of thermal stability required for use within a fuel cell environment.

  3. Nanoscale High Aspect Ratio Structures

    NASA Astrophysics Data System (ADS)

    Abbott, Jonathan; Davis, Robert; Vanfleet, Richard; Conley, Hiram

    2008-10-01

    Nanoscale high aspect ratio structures have possible applications in microfluidic channels, batteries, and fuel cells, among others. We present methods we have been trying to create 3:1 aspect ratio structures in transparent materials that will withstand temperatures needed for CVD or ALD processes; including contact molding, spin and etch back, and replica molding.

  4. 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.

  5. NANOSCALE STRUCTURALAND MAGNETIC CHARACTERIZATION USING

    E-print Network

    Dunin-Borkowski, Rafal E.

    backscattering. Technical advances in the high-resolution electron microscope (HREM) have resulted in performanceChapter 5 NANOSCALE STRUCTURALAND MAGNETIC CHARACTERIZATION USING ELECTRON MICROSCOPY David J The transmission electron microscope (TEM) is a powerful instrument for structural, chemical and magnetic

  6. 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.

  7. Structural reducibility of multilayer networks

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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%.

  8. 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

  9. Interfacial Scattering in Magnetic Multilayers

    NASA Astrophysics Data System (ADS)

    Stewart, D. A.; Zhang, X.-G.; Butler, W. H.

    2001-03-01

    The role of interfacial scattering in magnetic multilayers and its effects on transport and giant magnetoresistance are examined. The interfacial region is modeled as a randomly disordered alloy layer. The calculations were performed for a ComidCu multilayer using the Coherent Potential Approximation (CPA) in a layered Koringa-Kohn-Rostoker (LKKR) framework. The effect of this interfacial disorder on the multilayer non-local conductivity for different values of the electron momentum parallel to the layers, k_||, is explored. The influences of the interfacial layer thickness and k_|| on the non-local conductivity are also determined. A semi-classical boltzmann model for non-local conductivity is developed which incorporates the effects of surface roughness. The two approaches are compared and a k_|| dependent specularity parameter is obtained that varies with the disorder and thickness of the interfacial layer.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Integration of silver nanoparticle-impregnated polyelectrolyte multilayers into murine-splinted cutaneous wound beds.

    PubMed

    Guthrie, Kathleen M; Agarwal, Ankit; Teixeira, Leandro B C; Dubielzig, Richard R; Abbott, Nicholas L; Murphy, Christopher J; Singh, Harpreet; McAnulty, Jonathan F; Schurr, Michael J

    2013-01-01

    Silver is a commonly used topical antimicrobial. However, technologies to immobilize silver at the wound surface are lacking, while currently available silver-containing wound dressings release excess silver that can be cytotoxic and impair wound healing. We have shown that precise concentrations of silver at lower levels can be immobilized into a wound bed using a polyelectrolyte multilayer attachment technology. These silver nanoparticle-impregnated polyelectrolyte multilayers are noncytotoxic yet bactericidal in vitro, but their effect on wound healing in vivo was previously unknown. The purpose of this study was to determine the effect on wound healing of integrating silver nanoparticle/polyelectrolyte multilayers into the wound bed. A full-thickness, splinted, excisional murine wound healing model was employed in both phenotypically normal mice and spontaneously diabetic mice (healing impaired model). Gross image measurements showed an initial small lag in healing in the silver-treated wounds in diabetic mice, but no difference in time to complete wound closure in either normal or diabetic mice. Histological analysis showed modest differences between silver-treated and control groups on day 9, but no difference between groups at the time of wound closure. We conclude that silver nanoparticle/polyelectrolyte multilayers can be safely integrated into the wound beds of both normal and diabetic mice without delaying wound closure, and with transient histological effects. The results of this study suggest the feasibility of this technology for use as a platform to affect nanoscale wound engineering approaches to microbial prophylaxis or to augment wound healing. PMID:23511285

  17. Charge-Dependent Transport Switching of Single Molecular Ions in a Weak Polyelectrolyte Multilayer

    PubMed Central

    2015-01-01

    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 cm2/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

  18. Atomic Assembly of Magnetoresistive Multilayers

    E-print Network

    Wadley, Haydn

    chemical and structural complexity. The nature of the interfaces between the dissimilar materials used and simulation tools to the reactive, ion-assisted vapor deposition of multilay- ered structures. It is motivated's nanoscopically structured devices are made by controlling the condensation of an atomic or molecular vapor

  19. 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

  20. 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.

  1. 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

  2. Low-resistivity atomic-layer-deposited-TaN with atomic-layer-deposited-TaN/physical-vapor-deposited-Ta multilayer structure for multilevel Cu damascene interconnect

    SciTech Connect

    Furuya, Akira; Ohtsuka, Nobuyuki; Ohashi, Naofumi; Kondo, Seiichi; Ogawa, Shinichi

    2006-01-15

    One important issue for integrating atomic-layer-deposited (ALD) TaN barrier metal into Cu interconnects is a low thickness margin due to high electrical resistivity ({approx}50 m{omega} cm) of ALD-TaN. In investigating this issue, the median via resistance (0.16 {mu}m diameter vias) was found to increase from 0.5 to 26 {omega}/via as the ALD-TaN thickness was increased from 1 to 2 nm. To reduce the resistivity of ALD-TaN, its atomic concentration on various substrates was investigated. The N/Ta ratio of ALD-TaN was found to be about 4/5 on a SiO{sub 2} substrate but about 1/2 on a Ta substrate. We also confirmed that the Ta-rich ALD-TaN film on the Ta substrate had low electrical resistivity ({approx}2 m{omega} cm). We could thus successfully obtain low via resistance (5.4 {omega}/via) with thick ALD-TaN (5 nm) by using a PVD-Ta/ALD-TaN/PVD-Ta multilayer structure.

  3. 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

  4. Relation of thermal conductivity with process induced anisotropic void system in EB-PVD PYSZ thermal barrier coatings.

    SciTech Connect

    Renteria, A. F.; Saruhan, B.; Ilavsky, J.; German Aerospace Center

    2007-01-01

    Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of PYSZ-based ,TBC by tailoring its microstructure. Thermal conductivity of the EB-PVD produced PYSZ TBCs is influenced mainly by the size, shape, orientation and volume of the various types of porosity present in the coatings. These pores can be classified as open (inter-columnar and between feather arms gaps) and closed (intra-columnar pores). Since such pores are located within the three-dimensionally deposited columns and enclose large differences in their sizes, shapes, distribution and anisotropy, the accessibility for their characterization is very complex and requires the use of sophisticated methods. In this work, three different EB-PVD TBC microstructures were manufactured by varying the process parameters, yielding various characteristics of their pores. The corresponding thermal conductivities in as-coated state and after ageing at 1100C/1h and 100h were measured via Laser Flash Analysis Method (LFA). The pore characteristics and their individual effect on the thermal conductivity are analysed by USAXS which is supported by subsequent modelling and LFA methods, respectively. Evident differences in the thermal conductivity values of each microstructure were found in as-coated and aged conditions. In summary, broader columns introduce higher values in thermal conductivity. In general, thermal conductivity increases after ageing for all three investigated microstructures, although those with initial smaller pore surface area show smaller changes.

  5. Relation of Thermal Conductivity with Process Induced Anisotropic Void Systems in EB-PVD PYSZ Thermal Barrier Coatings

    SciTech Connect

    Renteria, A. Flores; Saruhan-Brings, B.; Ilavsky, J.

    2008-03-03

    Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of PYSZ-based TBC by tailoring its microstructure. Thermal conductivity of the EB-PVD produced PYSZ TBCs is influenced mainly by the size, shape, orientation and volume of the various types of porosity present in the coatings. These pores can be classified as open (inter-columnar and between feather arms gaps) and closed (intra-columnar pores). Since such pores are located within the three-dimensionally deposited columns and enclose large differences in their sizes, shapes, distribution and anisotropy, the accessibility for their characterization is very complex and requires the use of sophisticated methods. In this work, three different EB-PVD TBC microstructures were manufactured by varying the process parameters, yielding various characteristics of their pores. The corresponding thermal conductivities in as-coated state and after ageing at 11000C/1h and 100h were measured via Laser Flash Analysis Method (LFA). The pore characteristics and their individual effect on the thermal conductivity are analysed by USAXS which is supported by subsequent modelling and LFA methods, respectively. Evident differences in the thermal conductivity values of each microstructure were found in as-coated and aged conditions. In summary, broader columns introduce higher values in thermal conductivity. In general, thermal conductivity increases after ageing for all three investigated microstructures, although those with initial smaller pore surface area show smaller changes.

  6. 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.

  7. 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 of a core nanoscale molecular- wire crossbar memory (MWCM) [1], directly implementing the basic design, 32611, USA Abstract -- This paper proposes a nanoscale content addressable memory (CAM) architecture

  8. Multilayer weighted social network model.

    PubMed

    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. PMID:25493837

  9. 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.

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

    SciTech Connect

    Yadav, Satyesh K.; Wang, Jian; Misra, Amit; Liu, Xiang-Yang; Ramprasad, Ramamurthy

    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.

  11. 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.

  12. Mathematical Formulation of Multilayer Networks

    NASA Astrophysics Data System (ADS)

    De Domenico, Manlio; Solé-Ribalta, Albert; Cozzo, Emanuele; Kivelä, Mikko; Moreno, Yamir; Porter, Mason A.; Gómez, Sergio; Arenas, Alex

    2013-10-01

    A network representation is useful for describing the structure of a large variety of complex systems. However, most real and engineered systems have multiple subsystems and layers of connectivity, and the data produced by such systems are very rich. Achieving a deep understanding of such systems necessitates generalizing “traditional” network theory, and the newfound deluge of data now makes it possible to test increasingly general frameworks for the study of networks. In particular, although adjacency matrices are useful to describe traditional single-layer networks, such a representation is insufficient for the analysis and description of multiplex and time-dependent networks. One must therefore develop a more general mathematical framework to cope with the challenges posed by multilayer complex systems. In this paper, we introduce a tensorial framework to study multilayer networks, and we discuss the generalization of several important network descriptors and dynamical processes—including degree centrality, clustering coefficients, eigenvector centrality, modularity, von Neumann entropy, and diffusion—for this framework. We examine the impact of different choices in constructing these generalizations, and we illustrate how to obtain known results for the special cases of single-layer and multiplex networks. Our tensorial approach will be helpful for tackling pressing problems in multilayer complex systems, such as inferring who is influencing whom (and by which media) in multichannel social networks and developing routing techniques for multimodal transportation systems.

  13. 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.

  14. 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.

  15. 76 FR 76435 - Multilayered Wood Flooring From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-07

    ...731-TA-1179 (Final)] Multilayered Wood Flooring From China Determinations On the...those imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

  16. 75 FR 66126 - Multilayered Wood Flooring From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ...731-TA-1179 (Preliminary)] Multilayered Wood Flooring From China AGENCY: United States...reason of imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

  17. 75 FR 79019 - Multilayered Wood Flooring From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-17

    ...731-TA-1179 (Preliminary)] Multilayered Wood Flooring From China Determinations On the...reason of imports from China of multilayered wood flooring, provided for in subheadings...of U.S. manufacturers of multilayered wood flooring. The following companies...

  18. 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

  19. Young's Equation at the Nanoscale

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  20. Oxygen Detection via Nanoscale Optical Indicators

    E-print Network

    Ghosh, Ruby N.

    developed an optical technique for monitoring oxygen in both gas and liquid phases utilizing nanoscale metal. INTRODUCTION Real-time detection of oxygen in liquids and gases is important for a variety of chemicalOxygen Detection via Nanoscale Optical Indicators Ruby N. Ghosh Dept. of Physics Michigan State

  1. The Nanoscale Biophysics of Microscale Cell Adhesion

    E-print Network

    Tees, David F.J.

    The Nanoscale Biophysics of Microscale Cell Adhesion David F. J. Tees, Ph.D. Department of Physics://www.phy.ohiou.edu/~tees/current_research.html #12;Outline 1) Adhesion molecules and review of cell-scale phenomena 2) Force dependence of reaction Appendix 2--Bell model Appendix 3--Reliability theory #12;Cell Adhesion: Microscale to Nanoscale Cell 1

  2. CMOS Compatible Nanoscale Nonvolatile Resistance Switching

    E-print Network

    Cafarella, Michael J.

    CMOS Compatible Nanoscale Nonvolatile Resistance Switching Memory Sung Hyun Jo and Wei Lu studies on a nanoscale resistance switching memory structure based on planar silicon that is fully-terminal resistance switching devices show excellent scaling potential well beyond 10 Gb/cm2 and exhibit high yield

  3. SIMULATING NANOSCALE SEMICONDUCTOR DEVICES M. S. LASATER

    E-print Network

    SIMULATING NANOSCALE SEMICONDUCTOR DEVICES M. S. LASATER Center for Research in Scientific for in the design process for such small devices. One prototypical nanoscale semiconductor device under. Introduction In the next few decades, if the trend predicted by Moore's Law1 is to continue, semiconductor

  4. 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

  5. Extracytoplasmic Function (ECF) Sigma Factor Gene Regulation in Pseudomonas syringae: Integrated Molecular and Computational Characterization of PvdS-Regulated Promoters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The extracytoplasmic function (ECF) sigma factor PvdS regulates the expression of genes required for the biosynthesis and transport of pyoverdine, a siderophore that functions in iron acquisition. The production of pyoverdine is a distinctive trait of the fluorescent pseudomonads and the regulation ...

  6. 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

  7. 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.

  8. Multi-Layer E-Textile Circuits

    NASA Technical Reports Server (NTRS)

    Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

    2012-01-01

    Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

  9. Method of making coherent multilayer crystals

    DOEpatents

    Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

    1984-01-01

    A new material 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 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

  10. Unfolding the damping behavior of multilayer graphene membrane in the low-frequency regime.

    PubMed

    Lahiri, Debrupa; Das, Santanu; Choi, Wonbong; Agarwal, Arvind

    2012-05-22

    The damping behavior of few-layered graphene membrane in the low-frequency regime of mechanical loading is investigated in the present study. Damping of graphene has significant applications in micro/nanoscale devices and macroscale dynamic systems for absorbing shock-generated energies. Damping behavior of graphene is experimentally evaluated, for the first time, by dynamic mechanical analysis at the nanoscale with cyclic mechanical loading in the range 0.1-50 ?N applied at a frequency range of 10-250 Hz. This study reveals 260% higher damping on graphene membranes than a silicon surface. The damping shows excellent reproducibility and remains steady even after 100,000 cycles. The damping of multilayer graphene membrane, supported on a Si/SiO(2) substrate, shows a strong dependence on the frequency of cyclic loading. The mechanism governing impressive damping of a graphene membrane is elucidated by structural changes such as ripple formation, ripple wave propagation, and z-axis compression. Damping behavior of a graphene membrane in this low-frequency regime is also found to depend on the number of graphene layers and is explained as the interplay between in-plane sp(2) and out-of-plane van der Waals forces. These findings are important for establishing the potential of graphene for applications in macro- to nanoscale structures that require continuous absorption of shock waves without destruction/failure. PMID:22519730

  11. Macro- to Nanoscale Heat and Mass Transfer: The Lagging Behavior

    NASA Astrophysics Data System (ADS)

    Ghazanfarian, Jafar; Shomali, Zahra; Abbassi, Abbas

    2015-07-01

    The classical model of the Fourier's law is known as the most common constitutive relation for thermal transport in various engineering materials. Although the Fourier's law has been widely used in a variety of engineering application areas, there are many exceptional applications in which the Fourier's law is questionable. This paper gathers together such applications. Accordingly, the paper is divided into two parts. The first part reviews the papers pertaining to the fundamental theory of the phase-lagging models and the analytical and numerical solution approaches. The second part wrap ups the various applications of the phase-lagging models including the biological materials, ultra-high-speed laser heating, the problems involving moving media, micro/nanoscale heat transfer, multi-layered materials, the theory of thermoelasticity, heat transfer in the material defects, the diffusion problems we call as the non-Fick models, and some other applications. It is predicted that the interest in the field of phase-lagging heat transport has grown incredibly in recent years because they show good agreement with the experiments across a wide range of length and time scales.

  12. Multilayer Laue Lens Sequence Compiler

    Energy Science and Technology Software Center (ESTSC)

    2005-10-01

    For the growth of a new kind of x-ray focusing optic called a multilayer Laue lens, a device is constructed in which each layer of alernating high-z and low-z is placed in the appropriate place according to the Fresnel zone plate law. This requires that each layer have a different layer thickness. Because each layer is grown using DC magnetron sputter deposition, these layer thicknesses are not only dictated by the zone plate law, butmore »are adjusted to account for various drifting in the growth chamber due to target erosion, etc.« less

  13. Chromospheric and coronal observations with multilayer optics

    NASA Technical Reports Server (NTRS)

    Walker, Arthur B. C., Jr.; Hoover, Richard B.; Barbee, Troy W., Jr.

    1993-01-01

    The first high resolution X-ray images of an astronomical object (the solar corona) formed with normal incidence multilayer optics, were obtained in late 1987. We review the developments which have occurred in multilayer optics technology since 1987, and discuss the advantages that these developments present for solar observations. The most significant advantages of multilayer optics are: (1) telescopes with modest apertures (about 0.1-0.5 meters) can achieve images with very high (about 0.1-0.3 arcsec) resolution; and (2) the spectral selectivity of multilayers permits the investigation of thermal structures with resolution T/(Delta)T is about 5-10. We describe the analysis of polar plumes observed in 1987 and of small X-ray emitting regions called 'bright points' observed in 1991 to illustrate the power of multilayer optics for astronomical studies.

  14. 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.

  15. 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.

  16. 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.

  17. Nanoscale cryptography: opportunities and challenges

    NASA Astrophysics Data System (ADS)

    Masoumi, Massoud; Shi, Weidong; Xu, Lei

    2015-11-01

    While most of the electronics industry is dependent on the ever-decreasing size of lithographic transistors, this scaling cannot continue indefinitely. To improve the performance of the integrated circuits, new emerging and paradigms are needed. In recent years, nanoelectronics has become one of the most important and exciting forefront in science and engineering. It shows a great promise for providing us in the near future with many breakthroughs that change the direction of technological advances in a wide range of applications. In this paper, we discuss the contribution that nanotechnology may offer to the evolution of cryptographic hardware and embedded systems and demonstrate how nanoscale devices can be used for constructing security primitives. Using a custom set of design automation tools, it is demonstrated that relative to a conventional 45-nm CMOS system, performance gains can be obtained up to two orders of magnitude reduction in area and up to 50 % improvement in speed.

  18. Reactions inside nanoscale protein cages.

    PubMed

    Bode, Saskia A; Minten, Inge J; Nolte, Roeland J M; Cornelissen, Jeroen J L M

    2011-06-01

    Chemical reactions are traditionally carried out in bulk solution, but in nature confined spaces, like cell organelles, are used to obtain control in time and space of conversion. One way of studying these reactions in confinement is the development and use of small reaction vessels dispersed in solution, such as vesicles and micelles. The utilization of protein cages as reaction vessels is a relatively new field and very promising as these capsules are inherently monodisperse, in that way providing uniform reaction conditions, and are readily accessible to both chemical and genetic modifications. In this review, we aim to give an overview of the different kinds of nanoscale protein cages that have been employed as confined reaction spaces. PMID:21461437

  19. Nanoscale materials for hyperthermal theranostics

    NASA Astrophysics Data System (ADS)

    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.

  20. 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.

  1. 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.

  2. Self-organizing multilayer perceptron.

    PubMed

    Gas, Bruno

    2010-11-01

    In this paper, we propose an extension of a self-organizing map called self-organizing multilayer perceptron (SOMLP) whose purpose is to achieve quantization of spaces of functions. Based on the use of multilayer perceptron networks, SOMLP comprises the unsupervised as well as supervised learning algorithms. We demonstrate that it is possible to use the commonly used vector quantization algorithms (LVQ algorithms) to build new algorithms called functional quantization algorithms (LFQ algorithms). The SOMLP can be used to model nonlinear and/or nonstationary complex dynamic processes, such as speech signals. While most of the functional data analysis (FDA) research is based on B-spline or similar univariate functions, the SOMLP algorithm allows quantization of function with high dimensional input space. As a consequence, classical FDA methods can be outperformed by increasing the dimensionality of the input space of the functions under analysis. Experiments on artificial and real world examples are presented which illustrate the potential of this approach. PMID:20858579

  3. Studies on the effect of dispersoid(ZrO2) in PVdF-co-HFP based gel polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Sivakumar, M.; Subadevi, R.; Muthupradeepa, R.

    2013-06-01

    Gel polymer electrolytes containing poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) / Lithium bis(trifluoromethane sulfon)imide (LiTFSI) / mixture of ethylene carbonate and propylene carbonate (EC+PC) with different concendration of ZrO2 has been prepared using the solution casting technique. The conductivity of the prepared electrolyte sample has been determined by AC impedance technique in the range 303-353K. The temperature dependent ionic conductivity plot seems to obey VTF relation. The maximum ionic conductivity value of 4.46 × 10-3S/cm has been obtained for PVdF-co-HFP(32%) - LiTFSI(8%) - EC+PC (60%) + ZrO2(6wt%) based polymer electrolyte. The surface morphology of the prepared electrolyte sample has been studied using SEM.

  4. Nanoscale thermal transport. II. 2003–2012

    E-print Network

    Cahill, David G.

    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 ...

  5. 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 ...

  6. Tunable optical properties of multilayers black phosphorus

    E-print Network

    Low, Tony; Carvalho, A; Jiang, Yongjin; Wang, Han; Xia, Fengnian; Neto, A H Castro

    2014-01-01

    We calculated the optical conductivity tensor of multilayers black phosphorus using the Kubo formula within an effective low-energy Hamiltonian. The optical absorption spectra of multilayers black phosphorus are shown to vary sensitively with thickness, doping, and light polarization. In conjunction with experimental spectra obtained from infrared absorption spectroscopy, we discuss the role of interband coupling and disorder on the observed anisotropic absorption spectra. Multilayers black phosphorus might offer attractive alternatives to narrow gap compound semiconductors for optoelectronics across mid- to near-infrared frequencies.

  7. 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.

  8. Experimental investigations of multilayer insulation

    NASA Astrophysics Data System (ADS)

    Bapat, S. L.; Narayankhedkar, K. G.; Lukose, T. P.

    1990-08-01

    Multilayer insulation (MLI), using alternate layers of shield and spacer in high vacuum, is the most effective cryogenic insulation developed to date. Due to unpredictable changes in parameters such as winding pressure, uniform contact pressure and interstitial pressure, accurate theoretical prediction of MLI performance is very difficult. Thus, an experimental investigation has been carried out on a few indigenous MLI materials. The investigations are centred on the influence of the number of layers and layer density, with the cold boundary at the same temperature as liquid nitrogen. The experiments have been carried out using a cylindrical vessel with guard vessels on the top and bottom flat surfaces. The interstitial pressure, which depends on conditions pertaining to specific parameters, such as outgassing rate of materials, cryopumping speed and time for evacuation, has also been measured. The results are compared with those obtained from a theoretical analysis carried out for the same combination of shield and spacer materials.

  9. 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.

  10. Highly Efficient Multilayer Thermoelectric Devices

    NASA Technical Reports Server (NTRS)

    Boufelfel, Ali

    2006-01-01

    Multilayer thermoelectric devices now at the prototype stage of development exhibit a combination of desirable characteristics, including high figures of merit and high performance/cost ratios. These devices are capable of producing temperature differences of the order of 50 K in operation at or near room temperature. A solvent-free batch process for mass production of these state-of-the-art thermoelectric devices has also been developed. Like prior thermoelectric devices, the present ones have commercial potential mainly by virtue of their utility as means of controlled cooling (and/or, in some cases, heating) of sensors, integrated circuits, and temperature-critical components of scientific instruments. The advantages of thermoelectric devices for such uses include no need for circulating working fluids through or within the devices, generation of little if any noise, and high reliability. The disadvantages of prior thermoelectric devices include high power consumption and relatively low coefficients of performance. The present development program was undertaken in the hope of reducing the magnitudes of the aforementioned disadvantages and, especially, obtaining higher figures of merit for operation at and near room temperature. Accomplishments of the program thus far include development of an algorithm to estimate the heat extracted by, and the maximum temperature drop produced by, a thermoelectric device; solution of the problem of exchange of heat between a thermoelectric cooler and a water-cooled copper block; retrofitting of a vacuum chamber for depositing materials by sputtering; design of masks; and fabrication of multilayer thermoelectric devices of two different designs, denoted I and II. For both the I and II designs, the thicknesses of layers are of the order of nanometers. In devices of design I, nonconsecutive semiconductor layers are electrically connected in series. Devices of design II contain superlattices comprising alternating electron-acceptor (p)-doped and electron-donor (n)-doped, nanometer- thick semiconductor layers.

  11. Semi-analytical solutions for multilayer reservoirs 

    E-print Network

    Lolon, Elyezer Pabibak

    2001-01-01

    is only permitted in the wellbore, not in the reservoir). For simplicity, our solutions are presented and compared in terms of dimensionless variables (these variables are specifically formulated for the multilayer reservoir case). Our developments...

  12. Multilayer soft x-ray optics

    NASA Astrophysics Data System (ADS)

    Falco, Charles M.

    2014-10-01

    Molecular Beam Epitaxy (MBE) is able to produce high purity, epitaxial multilayer films with well defined interfaces. This precise deposition control along with a number of in situ characterization instruments allows a high degree of control over the formation of multilayers. We have three MBE systems, each with characteristics suitable for a subset of possible materials, that we have used to produce a large variety of x-ray multilayers. Together these MBE systems contain Reflection High Energy Electron Diffraction (RHEED), Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), X-Ray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS), Secondary Ion Mass Spectroscopy (SIMS), and Scanning Tunneling Microscopy (STM). Here I provide an overview of the techniques the students, postdocs, visiting scientists, and collaborators have used to select the materials pairs we have grown and analyzed for our x-ray multilayers.

  13. Fabrication of wedged multilayer Laue lenses

    DOE PAGESBeta

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack.more »This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.« less

  14. 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...

  15. Synthesis and evaluation of thermoelectric multilayer films

    SciTech Connect

    Wagner, A.V.; Foreman, R.J.; Summers, L.J.; Barbee, T.W. Jr.; Farmer, J.C.

    1996-03-21

    The deposition of compositionally modulated (Bi{sub 1-x}Sb{sub x}){sub 2}(Te{sub 1-y}Se{sub y}){sub 3} thermoelectric multilayer films by magnetron sputtering has been demonstrated. Structures with a period of 140{Angstrom} are shown to be stable to interdiffusion at the high deposition temperatures necessary for growth of single layer crystalline films with ZT {gt} 0.5. These multilayers are of the correct dimension to exhibit the electronic properties of quantum well structures. Furthermore it is shown that the Seebeck coefficient of the films is not degraded by the presence of this multilayer structure. It may be possible to synthesize a multilayer thermoelectric material with enhanced ZT by maximizing the barrier height through optimization of the composition of the barrier.

  16. Nanoporous silicon multilayers for terahertz filtering

    E-print Network

    Murphy, Thomas E.

    scale and scarcity of suf- ficiently transparent dielectric materials. Several techniques have been used to fabricate THz multilayer filters, including stacking and assem- bly of semiconductor wafers [1­5], ceramics

  17. 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.

  18. Fabrication of wedged multilayer Laue lenses

    SciTech Connect

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.

  19. 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 ...

  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. Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems

    PubMed Central

    Wohlhüter, Phillip; Bryan, Matthew Thomas; Warnicke, Peter; Gliga, Sebastian; Stevenson, Stephanie Elizabeth; Heldt, Georg; Saharan, Lalita; Suszka, Anna Kinga; Moutafis, Christoforos; Chopdekar, Rajesh Vilas; Raabe, Jörg; Thomson, Thomas; Hrkac, Gino; Heyderman, Laura Jane

    2015-01-01

    Vortices are fundamental magnetic topological structures characterized by a curling magnetization around a highly stable nanometric core. The control of the polarization of this core and its gyration is key to the utilization of vortices in technological applications. So far polarization control has been achieved in single-material structures using magnetic fields, spin-polarized currents or spin waves. Here we demonstrate local control of the vortex core orientation in hybrid structures where the vortex in an in-plane Permalloy film coexists with out-of-plane maze domains in a Co/Pd multilayer. The vortex core reverses its polarization on crossing a maze domain boundary. This reversal is mediated by a pair of magnetic singularities, known as Bloch points, and leads to the transient formation of a three-dimensional magnetization structure: a Bloch core. The interaction between vortex and domain wall thus acts as a nanoscale switch for the vortex core polarization. PMID:26238042

  2. Broadband Angular Selectivity of Light at the Nanoscale: Progress, Applications and Outlook

    E-print Network

    Shen, Yichen; Yeng, Yi Xiang; Joannopoulos, John D; Soljacic, Marin

    2015-01-01

    Humankind has long endeavored to control the propagation direction of light. Since time immemorial, shades, lenses and mirrors have been used to control the flow of light. In modern society, with the rapid development of nanotechnology, the control of light is moving toward devices at micrometer and even nanometer scales. At such scales, traditional devices based on geometrical optics reach their fundamental direction limits and cease to work. Nano photonics, on the other hand, has attracted wide attention from researchers, especially in the last decade, due to its ability to manipulate light at the nanoscale. This review focuses on the nano photonics systems that aim to select light based on its propagation direction. In the first half of this review, we survey the literature and the current state of the art focused on enabling optical broadband angular selectivity. The mechanisms we review can be classified into three main categories: (i) microscale geometrical optics, (ii) multilayer birefringent materials...

  3. Ordered organic-organic multilayer growth

    DOEpatents

    Forrest, Stephen R; Lunt, Richard R

    2015-01-13

    An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

  4. Optical multistability in a nonlinear Fibonacci multilayer

    NASA Astrophysics Data System (ADS)

    Dutta Gupta, Subhasish; Ray, Deb Shankar

    1988-08-01

    The transmission properties of a multilayered medium consisting of N nonlinear slabs are studied. A general characteristic matrix formalism is applied to obtain the power dependence of the transmission coefficient. As an application, a nonlinear Fibonacci multilayer with as many as 55 and 233 nonlinear slabs is considered. The nonlinear quasiperiodic system is shown to offer a wide variety of bi- stable and multistable operations.

  5. 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%.

  6. 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

    Structural and chemical investigations of CBD- and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se Available online 8 December 2004 Abstract It is known that high-efficiency thin film solar cells based on Cu(In,Ga)Se based on a Cu(In,Ga)Se2 (CIGS) and CuInSe2 (CIS) absorber layers have been achieved using a CdS buffer

  7. Thermal stability, complexing behavior, and ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid, [BMIM][BF4].

    PubMed

    Shalu; Chaurasia, S K; Singh, R K; Chandra, S

    2013-01-24

    PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior. PMID:23167848

  8. The role of interface thermal boundary resistance in the overall thermal conductivity of Si-Ge multilayered structures.

    PubMed

    Samvedi, Vikas; Tomar, Vikas

    2009-09-01

    Nanoscale engineered materials with tailored thermal properties are desirable for applications such as highly efficient thermoelectric, microelectronic and optoelectronic devices. It has been shown earlier that by judiciously varying the interface thermal boundary resistance (TBR), thermal conductivity in nanostructures can be controlled. In the presented investigation, the role of TBR in controlling thermal conductivity at the nanoscale is analyzed by performing non-equilibrium molecular dynamics (NEMD) simulations to calculate thermal conductivity of a range of Si-Ge multilayered structures with 1-3 periods, and with four different layer thicknesses. The analyses are performed at three different temperatures (400, 600 and 800 K). As expected, the thermal conductivity of all layered structures increases with the increase in the number of periods as well as with the increase in the monolayer thickness. Invariably, we find that the TBR offered by the interface nearest to the hot reservoir is the highest. This effect is in contrast to the usual notion that each interface contributes equally to the heat transfer resistance in a layered structure. Findings also suggest that for high period structures the average TBR offered by the interfaces is not equal. Findings are used to derive an analytical expression that describes period-length-dependent thermal conductivity of multilayered structures. PMID:19687536

  9. Ring-like solitons in plasmonic fiber waveguides composed of metal-dielectric multilayers.

    PubMed

    Yan, Jie-Yun; Li, Lu; Xiao, Jinghua

    2012-01-30

    We design a plasmonic fiber waveguide (PFW) composed of coaxial cylindrical metal-dielectric multilayers in nanoscale, and constitute the corresponding dynamical equations describing the propagation modes in the PFW with the Kerr nonlinearity in the dielectric layers. The physics is connected to the discrete matrix nonlinear Schrödinger equations, from which the highly confined ring-like solitons in scale of subwavelength are found both for the visible lights and the near-infrared lights in the self-defocusing condition. Moreover, when increasing the intensity of the input light the confinement can be further improved due to the cylindrical symmetry of the PFW, which means both the width and the radius of the ring are reduced. PMID:22330435

  10. Review of thermoelectric characterization techniques suitable for SiGe multilayer structures

    NASA Astrophysics Data System (ADS)

    Cecchi, Stefano; Ferre Llin, Lourdes; Etzelstorfer, Tanja; Samarelli, Antonio

    2015-03-01

    Thermoelectric materials have great potential for a range of energy harvesting applications, while the thin film approach is promising for the realization of integrated thermoelectric micro-devices. Silicon-germanium heterostructures are interesting candidates for on-chip cooling or energy harvesting, guaranteeing reliable manufacturing and integrability with silicon technology. Material research is nowadays focused on the engineering of nanostructured materials with improved thermoelectric performances. Therefore, the development of efficient methods for the characterizazion of the thermoelectric properties at the micro- and nano-scale is fundamental. We report here microfabrication based methods for the in-plane and cross-plane thermoelectric characterization of silicon-germanium multilayer heterostructures monolithically integrated on silicon. Contribution to the Topical Issue "Silicon and Silicon-related Materials for Thermoelectricity", edited by Dario Narducci.

  11. 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.

  12. Nanoscale assemblies and their biomedical applications

    PubMed Central

    Doll, Tais A. P. F.; Raman, Senthilkumar; Dey, Raja; Burkhard, Peter

    2013-01-01

    Nanoscale assemblies are a unique class of materials, which can be synthesized from inorganic, polymeric or biological building blocks. The multitude of applications of this class of materials ranges from solar and electrical to uses in food, cosmetics and medicine. In this review, we initially highlight characteristic features of polymeric nanoscale assemblies as well as those built from biological units (lipids, nucleic acids and proteins). We give special consideration to protein nanoassemblies found in nature such as ferritin protein cages, bacterial microcompartments and vaults found in eukaryotic cells and designed protein nanoassemblies, such as peptide nanofibres and peptide nanotubes. Next, we focus on biomedical applications of these nanoscale assemblies, such as cell targeting, drug delivery, bioimaging and vaccine development. In the vaccine development section, we report in more detail the use of virus-like particles and self-assembling polypeptide nanoparticles as new vaccine delivery platforms. PMID:23303217

  13. Bench-scale synthesis of nanoscale materials

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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), uniquely combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was initially demonstrated on a laboratory scale and was subsequently 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 sq m/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO2 produced by RTDS are included.

  14. 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.

  15. Interference in multilayer relativistic mirrors

    NASA Astrophysics Data System (ADS)

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Babaei, Javad; Taghipour, Meisam; Mohammadzadeh, Zahra

    2015-10-01

    In this paper, reflection coefficient of a relativistic ultra-thin electron multilayer is calculated using electromagnetic interference procedures. The relativistic electron layers are assumed to be formed by nonlinear plasma wake waves that constitute the electron density cusps. It is shown that the interference between successive relativistic mirrors is restricted by the condition, ? p ? ( 2 ? 0 ) 5 / 2 / ? p 0 , where ?p is the laser pulse duration. The results showed that tailoring the pulse amplitude, incident wave frequency value, incidence angle, and plasma density leads to increasing reflection coefficient a few orders of magnitudes. This constructive interference condition can be used for increasing conversion efficiency in the reflected energy from relativistic mirrors for the purpose of generating ultra-short coherence pulses in the extreme ultraviolet and x-ray regions. We also performed reflection from relativistic thin electron layers using relativistic 1D3V electromagnetic particle-in-cell (PIC) simulation. It was found that the results of PIC simulation are in agreement with analytical considerations.

  16. Multilayer heterostructures and their manufacture

    SciTech Connect

    Hammond, Scott R; Reese, Matthew; Rupert, Benjamin; Miedaner, Alexander; Curtis, Clavin; Olson, Dana; Ginley, David S

    2015-11-04

    A method of synthesizing multilayer heterostructures including an inorganic oxide layer residing on a solid substrate is described. Exemplary embodiments include producing an inorganic oxide layer on a solid substrate by a liquid coating process under relatively mild conditions. The relatively mild conditions include temperatures below 225.degree. C. and pressures above 9.4 mb. In an exemplary embodiment, a solution of diethyl aluminum ethoxide in anhydrous diglyme is applied to a flexible solid substrate by slot-die coating at ambient atmospheric pressure, and the diglyme removed by evaporation. An AlO.sub.x layer is formed by subjecting material remaining on the solid substrate to a relatively mild oven temperature of approximately 150.degree. C. The resulting AlO.sub.x layer exhibits relatively high light transmittance and relatively low vapor transmission rates for water. An exemplary embodiment of a flexible solid substrate is polyethylene napthalate (PEN). The PEN is not substantially adversely affected by exposure to 150.degree. C

  17. Visualizing Optoelectronic Processes at the Nanoscale.

    PubMed

    Mishra, Puneet; Komeda, Tadahiro

    2015-11-24

    In this issue of ACS Nano, Nienhaus et al. report the optoelectronic properties of carbon nanotube chiral junctions with nanometer resolution in the presence of strong electric fields (?1 V/nm). Here, we provide an overview of recent studies that combine scanning tunneling microscope (STM) and laser or microwave illumination. These techniques reveal nanoscale laser- or microwave-induced phenomena utilizing the intrinsic atomic resolution of the tunneling current, and do not require substantial modification of the STM itself. The merits of atomic-scale spatial resolution and chemical sensitivity of the laser or microwave spectroscopes make these techniques useful for nanoscale characterization. PMID:26524228

  18. Ultra-Fast Design Exploration of Nanoscale Circuits through

    E-print Network

    Mohanty, Saraju P.

    Ultra-Fast Design Exploration of Nanoscale Circuits through Metamodeling Presenter: Saraju P Nanoscale Design Challenges The Proposed Ultra-Fast Solution Metamodel Types and Proposed Techniques 04/27/2012 Mohanty 2 #12;Outline of the Talk Nanoscale Design Challenges The Proposed Ultra

  19. Ultra-Fast Design Exploration of Nanoscale Circuits through

    E-print Network

    Mohanty, Saraju P.

    Ultra-Fast Design Exploration of Nanoscale Circuits through Metamodeling Saraju P. Mohanty/26/2012 Presented By Oghenekarho Okobiah #12;Outline of the Talk Nanoscale Design Challenges The Proposed Ultra Nanoscale Design Challenges The Proposed Ultra-Fast Solution Metamodel Types and Proposed Techniques

  20. 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

  1. Tunable Nanoscale Localization of Energy on Plasmon Particle Arrays

    E-print Network

    Such a strong local response to far-field radiation on a single site of an array is equivalent to the response a nanoscale localized response to unfocused light that can be controlled by tuning the incident wavelength at the nanoscale. With the advent of novel techniques to structure materials on the nanoscale, the study of noble

  2. Multilayer thin film thermoelectrics produced by sputtering

    SciTech Connect

    Wagner, A.V.; Foreman, R.J.; Summers, L.J.; Barbee, T.W. Jr.; Farmer, J.C.

    1995-06-19

    In this work we explore the possibility of achieving bulk electrical properties in single layer sputter deposited films grown epitaxially on (111) oriented BaF{sub 2} substrates. There are a number of sputter deposition parameters that can be varied in order to optimize the film quality. It is important to understand the effect of varying the deposition temperature, Ar sputtering gas pressure, and the substrate bias. We will consider only Bi and Bi{sub 0.86}Sb{sub 0.14} films in this paper. These materials were chosen since they have the same simple structure, two different band gaps and do not change significantly either in physical or electrical properties with small amounts of cross contamination. We will also present our work on multilayer thermoelectrics made of Bi and Bi{sub 0.86}Sb{sub 0.14} layers. There has been considerable interest in this multilayer structure in the literature. Theoretical calculations of the band structure and interface states of these multilayer structures have been made by Mustafaev and Agassi et al. respectively [6,7]. Experimentally Yoshida et al. have examined similar multilayer structures grown by MBE as well as Bi/Sb multilayer samples in which report an anomalous thermoelectric power [8].

  3. 78 FR 30329 - Multilayered Wood Flooring from China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ...731-TA-1179 (Final) (Remand)] Multilayered Wood Flooring from China AGENCY: United States...731-TA-1179 (Final) concerning multilayered wood flooring (``MLWF'') from China...Floors, Inc.; BR Custom Surface; Real Wood Floors, LLC; Galleher Corp.; and...

  4. 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...

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

    E-print Network

    Müftü, Sinan

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

  6. Hard X-ray Microscopy with Multilayer Laue Lenses

    NASA Astrophysics Data System (ADS)

    Kang, Hyon Chol

    2011-03-01

    The possibility of imaging at near-atomic resolution using x-rays has been a dream ever since the short-wavelength nature of x-rays was demonstrated by von Laue and coworkers nearly a century ago. Even today the scientific impact of atomic-scale focusing of electromagnetic radiation would be deep and broad, because x-ray microscopy provides capabilities (ability to penetrate, sensitive and accurate elemental and structural information) that are complementary to other high-resolution microscopies. Although hard x-rays can in principle be focused to spot sizes on the order of their wavelength (0.1 nm), this limit has never been approached because of the difficulty in fabricating the optics. Multilayer Laue lens(MLL) is a novel diffractive optic for hard x-ray nano-focusing, which can be fabricated by sputter deposition of zone plate structure on flat substrate. According to the theoretical results, MLL is capable of focusing x-rays to well below 1 nm. We have demonstrated 2-dimensional focusing of hard x-rays with MLLs to a spot size of 25 nm x 27 nm with an efficiency of 2% at a photon energy of 12 keV, while 1-dimensional focus of 16 nm has been achieved. In this talk, we will present an overview of MLL microscopy and recent accomplishments for the determination of chemical composition in nanoscale systems. Lastly, we will give the capabilities of MLL microscopy that have the potential to significantly advance materials science, nanoscience, bio-medical science and environmental science.

  7. Continuous multilayered composite hydrogel as osteochondral substitute.

    PubMed

    Leone, G; Volpato, M D; Nelli, N; Lamponi, S; Boanini, E; Bigi, A; Magnani, A

    2015-08-01

    Cartilage is a highly organized avascular soft tissue that assembles from nano-to macro-scale to produce a complex structural network. To mimic cartilage tissue, we developed a stable multilayered composite material, characterized by a tailored gradient of mechanical properties. The optimized procedure implies chemical crosslinking of each layer directly onto the previous one and ensures a drastic reduction of the material discontinuities and brittleness. The multilayered composite was characterized by infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and scanning electron microscopy in order to compare its physico-chemical characteristics with those of cartilage tissue. The rheological behavior of the multilayered composite was similar to that of human cartilage. Finally its cytocompatibility toward chondrocytes and osteoblasts was evaluated. PMID:25504681

  8. Maximum screening fields of superconducting multilayer structures

    E-print Network

    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 $H_s$ 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 $\\sim 0.1\\; \\mu$m at the Nb surface could increase $H_s\\simeq 240$ mT of a clean Nb up to $H_s\\simeq 290$ mT. Optimized multilayers of Nb$_3$Sn, 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.

  9. 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.

  10. Tuning phase stability in nanocomposite multilayers

    NASA Astrophysics Data System (ADS)

    Thompson, G. B.; Banerjee, R.; Fraser, H. L.

    2003-10-01

    As thin-film layers in a multilayered stack are reduced in thickness, changes in phase stability can result within the individual layers. These changes in phase are expected to have a significant influence upon the functional properties of the nanostructured composite. The ability to engineer, or tune, phase stability at this nanometer length scale is of significant importance in order to maximize the functional properties of these materials. We report the prediction and experimental conformation of tuning the hcp to bcc phase stability in Ti for Ti/Nb multilayered nanocomposites. The prediction was based upon selective alloying of Ti with a bcc ? stabilizing element using a new form of a thermodynamic phase diagram for predicting phase stability in thin-film multilayers.

  11. High Spectral Resolution With Multilayer Gratings

    SciTech Connect

    Andre, J.-M.; Le Guen, K.; Jonnard, P.

    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.

  12. 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.

  13. 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.

  14. Evolutionary games on multilayer networks: A colloquium

    E-print Network

    Wang, Zhen; Szolnoki, Attila; Perc, Matjaz

    2015-01-01

    Networks form the backbone of many complex systems, ranging from the Internet to human societies. Accordingly, not only is the range of our interactions limited and thus best described and modeled by networks, it is also a fact that the networks that are an integral part of such models are often interdependent or even interconnected. Networks of networks or multilayer networks are therefore a more apt description of social systems. This colloquium is devoted to evolutionary games on multilayer networks, and in particular to the evolution of cooperation as one of the main pillars of modern human societies. We first give an overview of the most significant conceptual differences between single-layer and multilayer networks, and we provide basic definitions and a classification of the most commonly used terms. Subsequently, we review fascinating and counterintuitive evolutionary outcomes that emerge due to different types of interdependencies between otherwise independent populations. The focus is on coupling th...

  15. Adsorption Kinetics in Nanoscale Porous Coordination Polymers.

    PubMed

    Nune, Satish K; Thallapally, Praveen K; McGrail, Benard Peter; Annapureddy, Harsha V R; Dang, Liem X; Mei, Donghai; Karri, Naveen; Alvine, Kyle J; Olszta, Matthew J; Arey, Bruce W; Dohnalkova, Alice

    2015-10-01

    Nanoscale porous coordination polymers were synthesized using simple wet chemical method. The effect of various polymer surfactants on colloidal stability and shape selectivity was investigated. Our results suggest that the nanoparticles exhibited significantly improved adsorption kinetics compared to bulk crystals due to decreased diffusion path lengths and preferred crystal plane interaction. PMID:26333118

  16. Dynamic structural disorder in supported nanoscale catalysts

    SciTech Connect

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

    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.

  17. 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…

  18. 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

  19. FULL ARTICLE Nanoscale distinction of membrane patches

    E-print Network

    Gerwert, Klaus

    FULL ARTICLE Nanoscale distinction of membrane patches ­ a TERS study of Halobacterium salinarum Supporting information for this article is available free of charge under http://dx.doi.org/10.1002/jbio mechanisms take place at this site, ranging from transport of nutrients and waste to cell signalling events

  20. X-Ray Instrumentation Nanoscale Materials

    E-print Network

    Geysen, Mario

    X-Ray Instrumentation Nanoscale Materials Characterization Facilility (NMCF), Department-Crystal Diffractometer The Bruker Kappa Duo diffractometer combines molybdenum and copper X-ray sources with a highly accurate goniometer and one of the most sensitive CCD detectors (Apex II) for X-ray crystallography

  1. 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…

  2. 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 with lamellar thicknesses of 12 1 nm. We observed the melting of as few as 25 crystals. Over a wide number

  3. Patterning Nanoscale Structures by Surface Chemistry

    E-print Network

    Lu, Wei

    Patterning Nanoscale Structures by Surface Chemistry Wei Lu* and Dongchoul Kim Department combines spinodal decomposition, surface stress and surface chemistry. The simulation shows that the self-assembly process can be guided by tuning the surface chemistry of a substrate. An epilayer may evolve into various

  4. Traceable nanoscale measurement at NML-SIRIM

    SciTech Connect

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

    2012-06-29

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

  5. Imaging and Nanoscale Characterization Art Baddorf*

    E-print Network

    (d) Thomas Maier(d) Michael Summers(d) Mina Yoon Xiaoguang Zhang(d) Postdocs: Janakiraman Balachandran, Peter. Updated: 6/24/2015 Theme Leads Sergei Kalinin* Electronic and Ionic Functionality on the Nanoscale Bobby Microscopy Karren More Erica Lohman* Albina Borisevich(b) Jihua Chen* Dorothy Coffey(2)(b) Miaofang Chi David

  6. Ion beam modified Co/Si multilayers

    NASA Astrophysics Data System (ADS)

    Fallon, I. M.; Faunce, C. A.; Grundy, P. J.; Blythe, H. J.

    2000-05-01

    This article briefly reports microstructural, electrical transport, and magnetic measurements on Co/Si multilayers which are structurally modified by argon ion irradiation during growth. The periodicity and ferromagnetism of the multilayers is retained at ion energies approaching 400 eV. At and above this energy structural modification results in resputtering and thinning of the film, extensive mixing and a destruction of the periodic layered structure with the formation of nonequilibrium microstructures. The measurements show that the modified film is metallic in character, with the presence of low resistance paths and possible spin glass behavior in an amorphous matrix that surrounds a second microstructural component of mainly superparamagnetic nanoclusters.

  7. 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.

  8. Fabrication of multilayer pancakelike basic magnesium carbonate.

    PubMed

    Sun, Jinhe; Jia, Yongzhong; Yan Jing; Yao, Ying; Ma, Jun

    2014-10-01

    The properties of nanomaterials was strongly affected by their microstructures. Here Mg5(CO3)4(OH)2 x 4H2O multilayer pancakelike structures were fabricated successfully by reaction of MgCl2 and Na2CO3 in aqueous solution at 363 K. The growth process of nanostructures was observed by XRD and SEM. Several transition states of multilayer pancakelike basic magnesium carbonates were observed, which help to understand better the formation process of this hierarchical nanostructures. The formation mechanism of Mg5(CO3)4(OH)2 x 4H2O multilayer pancakelike structures was discussed and helical growth was proposed. The amorphous nanoparticles were formed firstly. Then nanopartilces aggregated and oriented assembly under the direction of chemical bonds with the help of water molecules. The multilayer pancakelike basic magnesium carbonates was formed by helical growth of wafers along (100) and (001) direction. The diameter and volume decreased with the increasing concentration of reactants. PMID:25942931

  9. ENTROPY MINIMIZATION ALGORITHM FOR MULTILAYER PERCEPTRONS

    E-print Network

    Slatton, Clint

    ENTROPY MINIMIZATION ALGORITHM FOR MULTILAYER PERCEPTRONS Deniz Erdogmus, Jose C. Principe,principe]@cneI.ufl.edu ABSTRACT We have previously proposed the use of quadratic Renyi's error entropy with a Parzen density entropy criterion imposes the minimization of average information content in the error signal rather than

  10. ENTROPY MINIMIZATION ALGORITHM FOR MULTILAYER PERCEPTRONS

    E-print Network

    Slatton, Clint

    ENTROPY MINIMIZATION ALGORITHM FOR MULTILAYER PERCEPTRONS Deniz Erdogmus, Jose C. Principe,principe]@cnel.ufl.edu ABSTRACT We have previously proposed the use of quadratic Renyi's error entropy with a Parzen density entropy criterion imposes the minimization of average information content in the error signal rather than

  11. Theory of magnetoelectric effects in multilayer composites

    NASA Astrophysics Data System (ADS)

    Bichurin, M. I.; Petrov, V. M.; Srinivasan, G.

    2002-03-01

    A theoretical model is presented for magnetoelectric (ME) effects in bilayer and multilayer composites. Early models are based on ideal interface or the absence of friction, conditions that are not satisfied in real materials [1]. In addition, one needs to understand our recent observations showing considerable discrepancy between data on ME voltage coefficients in bilayer and multilayer composites [2]. A novel approach to take into account the actual boundary conditions in multilayer composites is proposed. An averaging method is used for deriving effective material parameters in composites. With the modified boundary conditions and the effective material parameters, we obtain expressions for ME voltage coefficients for multilayers. The estimated ME coupling constants are compared with data for lithium ferrite-lead zirconate titanate (PZT) and nickel ferrite-PZT composites. - work supported by a grant from the NSF (DMR-0072144) 1. G. Harshe, J.O. Dougherty, and R. E. Newnham, Int. J. Appl. Electromagn. Mater. 4, 145 (1993). 2. G. Srinivasan, E. T. Rasmussen, J. Gallegos, R. Srinivasan, Yu. I. Bokhan, and V. M. Laletin, Phys. Rev. B 64, 214408 (2001).

  12. Multilayer Film Assembly of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

    2000-01-01

    An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

  13. Theoretical modeling of bifunctional multilayer systems

    NASA Astrophysics Data System (ADS)

    Ellis, D. E.; Tubman, N. M.; Wells, D. M.

    Crystalline multilayer systems with structure ABABA... offer the possibility of combining functional properties of two distinctly different materials, and of exploiting the interfaces to couple functionality of one component to the other. The multilayer environment permits the amplification of interface properties as would be important for device applications. The manipulation of ferroelectric, ferromagnetic, and/or ferroelastic properties in so-called ferroic materials through growth of thin films, multilayers, and graded composition structures has received considerable experimental and theoretical attention in recent years. We survey the current status of atomic-scale modeling of multilayer systems which could exhibit ferroic behavior; i.e., spontaneous order below a critical temperature and hysteresis in stimulus-response behavior. The roles of interfacial strain, chemical variability at the interface, and film thickness are explored, taking as a primary example the classic BaTiO3?Fe3O4 ferroelectric ? ferrimagnetic interactions. First principles band structure calculations are used to determine relaxed interface structures and residual stresses, as well as the underlying electronic distributions. Embedded cluster methods are then used to extract local chemical bonding characteristics and hyperfine properties.

  14. Theoretical modeling of bifunctional multilayer systems

    NASA Astrophysics Data System (ADS)

    Ellis, D. E.; Tubman, N. M.; Wells, D. M.

    2007-09-01

    Crystalline multilayer systems with structure ABABA... offer the possibility of combining functional properties of two distinctly different materials, and of exploiting the interfaces to couple functionality of one component to the other. The multilayer environment permits the amplification of interface properties as would be important for device applications. The manipulation of ferroelectric, ferromagnetic, and/or ferroelastic properties in so-called ferroic materials through growth of thin films, multilayers, and graded composition structures has received considerable experimental and theoretical attention in recent years. We survey the current status of atomic-scale modeling of multilayer systems which could exhibit ferroic behavior; i.e., spontaneous order below a critical temperature and hysteresis in stimulus-response behavior. The roles of interfacial strain, chemical variability at the interface, and film thickness are explored, taking as a primary example the classic BaTiO3 ??Fe3O4 ferroelectric??ferrimagnetic interactions. First principles band structure calculations are used to determine relaxed interface structures and residual stresses, as well as the underlying electronic distributions. Embedded cluster methods are then used to extract local chemical bonding characteristics and hyperfine properties.

  15. Computing and Fabricating Multilayer Models Michael Holroyd

    E-print Network

    Popovic, Jovan

    printing [Dimitrov et al. 2006] and multi- axis milling. However, despite these advances, producing a 3D undermine the intended 3D effect. We describe a fast method for computing a correction factor 3D model into a multilayer model: a parallel stack of high-resolution 2D images embedded within

  16. 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.

  17. Coherent multilayer crystals and method of making

    DOEpatents

    Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Tucson, AZ)

    1984-01-01

    A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2.ANG. to 100.ANG. or more in thickness.

  18. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    SciTech Connect

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-06

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

  19. Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens

    NASA Astrophysics Data System (ADS)

    Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

    2012-11-01

    Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

  20. 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

  1. 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.

  2. Programmed assembly of nanoscale structures using peptoids.

    SciTech Connect

    Ren, Jianhua; Russell, Scott; Morishetti, Kiran; Robinson, David B.; Zuckermann, Ronald N.; Buffleben, George M.; Hjelm, Rex P.; Kent, Michael Stuart

    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.

  3. Nanoscale sensing devices for turbulence measurements

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Arwatz, G.; Van Buren, T. W.; Hoffman, D. E.; Hultmark, M.

    2015-07-01

    A collection of nanoscale sensing devices developed specifically for high-frequency turbulence measurements is presented. The new sensors are all derived from the nanoscale thermal anemometry probe (NSTAP), which uses a free-standing platinum wire as active sensing element. Each sensor is designed and fabricated to measure a specific quantity and can be customized for special applications. In addition to the original NSTAP (for single-component velocity measurement), the new sensors include the T-NSTAP (for temperature measurement), the x-NSTAP (for two-component velocity measurement), and the q-NSTAP (for humidity measurement). This article provides a summary of the NSTAP family including details of design and fabrication as well as presentation of flow measurements using these sensors. Also, a custom-made constant-temperature anemometer that allows proper operation of the NSTAP sensors will be introduced.

  4. Relaxation of Polyisoprene in Nanoscale Confinement

    NASA Astrophysics Data System (ADS)

    Kim, Sung A.; Agarwal, Praveen; Archer, Lynden

    2012-02-01

    This talk introduces a simple model of confined polymers in polymer nanoparticle composites. Most studies about confined polymer dynamics have been investigated from the system of polymers in porous media or the polymer thin film structure. This new class of polymer nanoparticle hybrid materials, termed Nanoscale Ionic Materials (NIMs), is synthesized in bulk scale with convenient controllability of diverse properties to create the confined polymers in nanoscale. cis-Polyisoprene (PI), type A polymer whose dipole moments are parallel along the chain backbone, are synthesized by anionic polymerization and then tethered to spherical silica nanoparticles. Broadband Dielectric Spectroscopy measures responses to the applied electric field which are normal mode relaxation indicative of whole chain relaxation, and also segmental relaxation. We show that relaxations of PI are slower when simultaneously confined and tethered. We also show that molecular weight and grafting density have a profound effect on dynamics of the twice-confined PI chains.

  5. Structure sensitivity and nanoscale effects in electrocatalysis

    NASA Astrophysics Data System (ADS)

    Koper, Marc T. M.

    2011-05-01

    This review discusses the role of the detailed nanoscale structure of catalytic surfaces on the activity of various electrocatalytic reactions of importance for fuel cells, hydrogen production, and other environmentally important catalytic reactions, such as carbon monoxide oxidation, methanol and ethanol oxidation, ammonia oxidation, nitric oxide reduction, hydrogen evolution, and oxygen reduction. Specifically, results and insights obtained from surface-science single-crystal-based model experiments are linked to experiments on well-defined shape-controlled nanoparticles. A classification of structure sensitive effects in electrocatalysis is suggested, based both on empirical grounds and on quantum-chemical viz. thermochemical considerations. The mutual relation between the two classification schemes is also discussed. The review underscores the relevance of single-crystal modeling of nanoscale effects in catalysis, and points to the special role of two kinds of active sites for electrocatalysis on nanoparticulate surfaces: (i) steps and defects in (111) terraces or facets, and (ii) long-range (100) terraces or facets.

  6. Nanoscale thermal transport. II. 2003–2012

    SciTech Connect

    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

    2014-03-15

    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.

  7. 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.

  8. Nanoscale molecularly imprinted polymers and method thereof

    DOEpatents

    Hart, Bradley R. (Brentwood, CA); Talley, Chad E. (Brentwood, CA)

    2008-06-10

    Nanoscale molecularly imprinted polymers (MIP) having polymer features wherein the size, shape and position are predetermined can be fabricated using an xy piezo stage mounted on an inverted microscope and a laser. Using an AMF controller, a solution containing polymer precursors and a photo initiator are positioned on the xy piezo and hit with a laser beam. The thickness of the polymeric features can be varied from a few nanometers to over a micron.

  9. Small is Different: Nanoscale Computational Microscopy

    NASA Astrophysics Data System (ADS)

    Landman, Uzi

    2015-03-01

    Finite materials systems of reduced sizes exhibit discrete quantized energy level spectra and specific structures and morphologies, which are manifested in unique, nonscalable, size-dependent physical and chemical properties. Indeed, when the scale of materials structures is reduced to the nanoscale, emergent phenomena often occurs, that is not commonly expected, or deduced, from knowledge learned at larger sizes. Characterization and understanding of the size-dependent evolution of the properties of materials aggregates are among the major challenges of modern materials science. Computer-based classical and quantum computations and simulations are tools of discovery of nanoscale emergent behavior. We highlight such behavior in diverse systems, including: (i) Atomistic simulations of nanoscale liquid jets and bridges and the stochastic hydrodynamic description of their properties; (ii) Metal nanoclusters and their self-assembled superlattices exhibiting stabilities and properties originating from superatom electronic shell-closing, atom packing, and interactions between protecting ligands; (iii) Electric-field-induced shape-transitions and electrocrystallization of liquid droplets, and (iv) Symmetry-breaking and formation of highly-correlated Wigner molecules between electrons in 2D quantum dots and bosons in traps.

  10. Polyelectrolyte multilayers: An odyssey through interdisciplinary science

    NASA Astrophysics Data System (ADS)

    Jaber, Jad A.

    This dissertation provides an overview of a self assembled multilayer technique based on the alternating deposition of oppositely charged polyelectrolytes onto charged solid supports. The basic principles and methodologies governing this technique are laid down, and new strategies are built upon the latter, in an effort to develop innovative technologies that would be beneficial for making new products or improving the quality of existing ones. Fundamental studies to characterize the water content, efficiency of ion-pairing, differential strength of electrostatic interactions, topology, and viscoelastic properties of polyelectrolyte multilayers, PEMUs, are illustrated and conducted. In addition, polyelectrolyte multilayers that are stimulus responsive, or support active and controlled bio-motor protein interactions are described. Attenuated total reflectance Fourier transform infrared, (ATR), spectroscopy was used to compare the extent of swelling and doping within PAH/PSS and PDADMA/PSS polyelectrolyte multilayers. Unlike PDADMA/PSS, whose water content depended on the solution ionic strength, PAH/PSS was resistant to swelling by salt. It was stable up to 4.0 M sodium chloride, with 6 water molecules per ion-pair. Using the infrared active perchlorate sodium salt, the amount of residual persistent extrinsic sites in both PDADMA/PSS and PAH/PSS was determined to be 3% and 6%, respectively. The free energy of association between the polymer segments, in the presence of sodium perchlorate, was in the order of 4.5 kJ mol-1 and -9.5 kJ mol-1 for PDADMA/PSS and PAH/PSS correspondingly. Thus, indicating the relatively strong electrostatic association between the polymer segments in a PAH/PSS relative to PDADMA/PSS multilayer. Adjusting the pH of the solution in contact with the PAH/PSS multilayer to 11.5 resulted in a first order discontinuous dissociation of the Pol+Pol- bonds. Techniques used to study the mechanical properties of single muscle fiber were adapted to characterize the topology, viscoelastic behavior, complex modulus and loss factor of PDADMA/PSS multilayers, over a range of frequencies and strain amplitudes. Tensile mode (transient uniaxial stretching) of a PEMU microcoupon using a capacitative-type force transducer located on a modified stage of inverted microscope revealed evidence on the viscous-like behavior of polymer chains within PEMU. Dependence of viscosity was primarily on the ionic strength of the bathing solution, with appreciable stress relaxation occurring at high salt concentrations. Dynamic mechanical analysis was then used to determine the damping properties of PEMU where the length was oscillated sinusoidally, and the resulting force, amplitude and phase shift were observed. Compared to other commercially available polymer damping materials such as acrylic and rubber adhesives, PEMU demonstrated up to 250% enhancement in damping properties over the frequency range of 0.3-10 Hz. This was obtained while the multilayer dry thickness was 3000% less then that of the conventional adhesives. The synthesis of charged copolymers of poly(N-isopropylacrylamide), (PNIPAM), and their use in constructing thermally responsive PEMU were demonstrated. The temperature dependent water content of the thin film, studied in situ using ATR-FTIR spectroscopy, revealed microscopic and macroscopic transitions at 33 and 45°C, respectively. About 7 water molecules per NIPAM repeat unit were found to be reversibly lost from, or recovered by, the film upon cycling over a temperature range of 10 to 55°C. Assuming that each ion-pair represents a crosslink, swelling theory was used to translate these results into polymer-solvent interaction parameters and enthalpies of mixing for the various polymer components. In addition, the flux of a charged probe molecule, potassium ferricyanide, through the NIPAM-rich multilayer was assessed with rotating disk electrode voltammetry. Thermally reversible modulation of ion transport was demonstrated. Positive polyelectrolytes were investigated as new surface coatings for promoting in vi

  11. 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.

  12. 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.

  13. Interaction of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide with an electrospun PVdF membrane: Temperature dependence of the concentration of the anion conformers.

    PubMed

    Vitucci, F M; Palumbo, O; Trequattrini, F; Brubach, J-B; Roy, P; Meschini, I; Croce, F; Paolone, A

    2015-09-01

    We measured the temperature dependence of the infrared absorption spectrum of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PY R14-TFSI) between 160 and 330 K, through all the phase transitions presented by this compound. The comparison of the experimental spectra with the calculated vibration modes of different conformers of the ions composing the ionic liquid allowed to detect the presence of both conformers of TFSI in the liquid, supercooled, and glass phases, while only the trans-conformer is retained in both solid phases. When the ionic liquid swells a polyvinylidenefluoride (PVdF) electrospun membrane, the cis-rotamer is detected in all phases, since the interaction between the polymer and the ionic liquid inhibits the complete transformation of TFSI into the trans-conformer in the solid phases. Computational results confirm that in the presence of a PVdF chain, cis-TFSI becomes the lowest energy conformer. Therefore, the interaction with the polymer alters the physical properties of the ionic liquid. PMID:26342383

  14. Interaction of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide with an electrospun PVdF membrane: Temperature dependence of the concentration of the anion conformers

    NASA Astrophysics Data System (ADS)

    Vitucci, F. M.; Palumbo, O.; Trequattrini, F.; Brubach, J.-B.; Roy, P.; Meschini, I.; Croce, F.; Paolone, A.

    2015-09-01

    We measured the temperature dependence of the infrared absorption spectrum of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PY R14-TFSI) between 160 and 330 K, through all the phase transitions presented by this compound. The comparison of the experimental spectra with the calculated vibration modes of different conformers of the ions composing the ionic liquid allowed to detect the presence of both conformers of TFSI in the liquid, supercooled, and glass phases, while only the trans-conformer is retained in both solid phases. When the ionic liquid swells a polyvinylidenefluoride (PVdF) electrospun membrane, the cis-rotamer is detected in all phases, since the interaction between the polymer and the ionic liquid inhibits the complete transformation of TFSI into the trans-conformer in the solid phases. Computational results confirm that in the presence of a PVdF chain, cis-TFSI becomes the lowest energy conformer. Therefore, the interaction with the polymer alters the physical properties of the ionic liquid.

  15. 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 ...

  16. 75 FR 49487 - Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... AGENCY Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray AGENCY: Environmental Protection... period for the draft document ``Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray'' (EPA.... ] ADDRESSES: The draft ``Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray'' is...

  17. 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

    2015-07-14

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

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

    DOEpatents

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

    2015-11-03

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

  19. 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.

  20. Deconvolution of mixed magnetism in multilayer graphene

    SciTech Connect

    Swain, Akshaya Kumar; Bahadur, Dhirendra

    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. Multiple wavelength photolithography for preparing multilayer microstructures

    DOEpatents

    Dentinger, Paul Michael (Livermore, CA); Krafcik, Karen Lee (Livermore, CA)

    2003-06-24

    The invention relates to a multilayer microstructure and a method for preparing thereof. The method involves first applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer. A portion of the first photodefinable composition is then exposed to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer. After exposing the first polymeric layer, a second photodefinable composition having a second exposure wavelength is applied on the first polymeric layer to form a second polymeric layer. A portion of the second photodefinable composition is then exposed to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer. In addition, a portion of each layer is removed according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portions removed.

  2. Polyelectrolyte Multilayering on a Charged Sphere

    E-print Network

    Rene Messina; Christian Holm; Kurt Kremer

    2003-06-16

    The adsorption of highly \\textit{oppositely} charged flexible polyelectrolytes onto a charged spherical surface is investigated by means of Monte Carlo simulations in a fashion which resembles the layer-by-layer deposition technique introduced by Decher. Electroneutrality is insured at each step by the presence of monovalent counterions (anions and cations). We study in detail the structure of the \\textit{equilibrium} complex. Our investigations of the first few layer formations strongly suggest that multilayering in spherical geometry is not possible as an equilibrium process with purely electrostatic interactions. We especially focus on the influence of specific (non-electrostatic) short range attractive interactions (e.g., Van der Waals) on the stability of the multilayers.

  3. 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.

  4. 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.

  5. Multi-layer waste containment barrier

    SciTech Connect

    Smith, A.M.; Gardner, B.M.; Nickelson, D.F.

    1999-10-05

    An apparatus is described for constructing an underground containment barrier for containing an in-situ portion of earth. The apparatus includes an excavating device for simultaneously (1) 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 (2) 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.

  6. Resonant evanescent complex fields on dielectric multilayers.

    PubMed

    Angelini, Angelo

    2015-12-15

    Complex light fields, including evanescent Bessel beams, can be generated at dielectric interfaces by means of oil-immersion optics operating in total internal reflection conditions. Here we report on the observation of evanescent complex fields produced on a dielectric multilayer through the interference of surface modes resonantly sustained by the multilayer itself. The coupling to surface modes is attained by modifying the wavefront of an incident laser beam in such a way that the resulting intensity distribution in k-space matches the dispersion of the surface mode. The phase of surface modes can be further controlled, and two-dimensional vortex beams can also be produced according to the same working principle. PMID:26670502

  7. Information Propagation in Clustered Multilayer Networks

    E-print Network

    Zhuang, Yong

    2015-01-01

    In today's world, individuals interact with each other in more complicated patterns than ever. Some individuals engage through online social networks (e.g., Facebook, Twitter), while some communicate only through conventional ways (e.g., face-to-face). Therefore, understanding the dynamics of information propagation among humans calls for a multi-layer network model where an online social network is conjoined with a physical network. In this work, we initiate a study of information diffusion in a clustered multi-layer network model, where all constituent layers are random networks with high clustering. We assume that information propagates according to the SIR model and with different information transmissibility across the networks. We give results for the conditions, probability, and size of information epidemics, i.e., cases where information starts from a single individual and reaches a positive fraction of the population. We show that increasing the level of clustering in either one of the layers increas...

  8. Advances in polyelectrolyte multilayer nanofilms as tunable drug delivery systems

    PubMed Central

    Jiang, Bingbing; Barnett, John B; Li, Bingyun

    2009-01-01

    There has been considerable interest in polyelectrolyte multilayer nanofilms, which have a variety of applications ranging from optical and electrochemical materials to biomedical devices. Polyelectrolyte multilayer nanofilms are constructed from aqueous solutions using electrostatic layer-by-layer self-assembly of oppositely-charged polyelectrolytes on a solid substrate. Multifunctional polyelectrolyte multilayer nanofilms have been studied using charged dyes, metal and inorganic nanoparticles, DNA, proteins, and viruses. In the past few years, there has been increasing attention to developing polyelectrolyte multilayer nanofilms as drug delivery vehicles. In this mini-review, we present recent developments in polyelectrolyte multilayer nanofilms with tunable drug delivery properties, with particular emphasis on the strategies in tuning the loading and release of drugs in polyelectrolyte multilayer nanofilms as well as their applications. PMID:24198464

  9. Normal incidence multilayer mirrors for extreme ultraviolet astronomy

    NASA Technical Reports Server (NTRS)

    Stern, R. A.; Haisch, B. M.; Joki, E. G.; Catura, R. C.

    1984-01-01

    Sputtered multilayer coatings allow the use of normal incidence optics in the extreme ultraviolet (EUV) region below 500 A. Multilayer mirrors can be tailored to provide images at strong EUV lines in the sun and stars, in many cases making more efficient use of the telescope aperture than grazing incidence optics. Alternatively, the bandpass can be broadened at the expense of peak effective area, by varying the multilayer structure over the mirror surface. Such mirrors can also serve as optical elements in spectrographs for investigation of specific emission and absorption line complexes, and are self-filtering in that they reject nearby geocoronal and cosmic resonance line backgrounds. Current efforts at the Lockheed Palo Alto Research Laboratory in the design, fabrication, and testing of EUV multilayer mirrors are discussed. This program includes the design and fabrication of normal incidence EUV multilayer mirrors, and the deposition of multilayers on lacquer-coated substrates.

  10. Semiconductor Laser With Multilayer Dielectric Reflector

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Multilayer dielectric reflector included in proposed surface-emitting, distributed-feedback, grating semiconductor laser (e.g., a GaAlAs device). Contributes to efficiency and output power of laser by reducing amount of light entering substrate, where wasted by absorption. Index of refraction in reflector sublayers alternates between higher and lower value. Higher value less than effective index of refraction of waveguide layer.

  11. Apparent Thermal Conductivity Of Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Mcintosh, Glen E.

    1995-01-01

    Mathematical model of apparent or effective thermal conductivity between two successive layers of multilayer thermal insulation (MLI) offers potential for optimizing performance of insulation. One gains understanding of how each physical mechanism contributes to overall flow of heat through MLI blanket. Model helps analyze engineering tradeoffs among such parameters as number of layers, thicknesses of gaps between layers, types of spacers placed in gaps, weight, overall thickness, and effects of foregoing on apparent thermal conductivity through blanket.

  12. 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.

  13. Adsorption of ammonia on multilayer iron phthalocyanine

    SciTech Connect

    Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim; Schulte, Karina; Wang Bin; Bocquet, Marie-Laure

    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.

  14. Nonlinear waves in a multilayer system

    NASA Astrophysics Data System (ADS)

    Simanovskii, Ilya B.; Viviani, Antonio; Dubois, Frank; Legros, Jean-Claude

    2009-02-01

    The joint action of buoyant and thermocapillary mechanisms of instability in a multilayer system, is investigated. The nonlinear convective regimes are studied by the finite difference method. The periodic boundary conditions on the lateral boundaries, are considered. It is found that the competition of both mechanisms of instability may lead to the appearance of a buoyant-thermocapillary traveling wave and a modulated traveling wave. To cite this article: I.B. Simanovskii et al., C. R. Mecanique 337 (2009).

  15. Modeling of composite materials and multilayered structures

    SciTech Connect

    Touratier, M.

    1993-12-31

    The aim of this paper is to present efficient tools for predicting mechanical properties of most of the usual composite materials, and the response to the loading for multilayered structures. The essence of these tools is such that they are especially appropriate to the design of composite constructions. Three types of composite materials have been considered: composite materials with a matrix reinforced by long parallel fibers; composite materials with a matrix reinforced by randomly distributed short fibers; and last, two-dimensional woven fabric composites. For all these composite materials homogenized elastic properties are given and some indications are provided for hygrothermal properties. Experimental techniques in statics and in dynamics by ultrasonic wave propagation have allowed us to validate the above homogenization models. In order to provide a complete set of tools for the composite designer, a multilayered, doubly curved shallow shell model has been designed. This model is based on a new type of kinematics which has a three-dimensional essence and allows us to take into account a proper transverse shear deformation distribution and avoid transverse shear correction factors. Finally, contact conditions at interfaces between layers of the laminate have been taken into account both for displacements and for transverse shear stresses, the latter satisfying the free boundary conditions upon the top and bottom surfaces of the multilayered structures. Thus this model allows for instance, analyzing interface stresses useful to the design of composite structures in order to prevent delamination. The analysis may use analytical and/or finite element computations.

  16. Evolutionary games on multilayer networks: a colloquium

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wang, Lin; Szolnoki, Attila; Perc, Matjaž

    2015-05-01

    Networks form the backbone of many complex systems, ranging from the Internet to human societies. Accordingly, not only is the range of our interactions limited and thus best described and modeled by networks, it is also a fact that the networks that are an integral part of such models are often interdependent or even interconnected. Networks of networks or multilayer networks are therefore a more apt description of social systems. This colloquium is devoted to evolutionary games on multilayer networks, and in particular to the evolution of cooperation as one of the main pillars of modern human societies. We first give an overview of the most significant conceptual differences between single-layer and multilayer networks, and we provide basic definitions and a classification of the most commonly used terms. Subsequently, we review fascinating and counterintuitive evolutionary outcomes that emerge due to different types of interdependencies between otherwise independent populations. The focus is on coupling through the utilities of players, through the flow of information, as well as through the popularity of different strategies on different network layers. The colloquium highlights the importance of pattern formation and collective behavior for the promotion of cooperation under adverse conditions, as well as the synergies between network science and evolutionary game theory.

  17. Technique for etching monolayer and multilayer materials

    DOEpatents

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  18. Physical Properties of PC-PMMA Multilayers

    NASA Astrophysics Data System (ADS)

    Rahman, Arifur; Baer, Eric; Chipara, Alin Cristian; Vajtai, Robert; Ajayan, Pullickel M.; Hinthorne, James; Elamin, Ibrahim; Chipara, Mircea; Eric Baer Collaboration; Pullickel Ajayan Collaboration; Mircea Chipara Collaboration

    2015-03-01

    Multilayers of polycarbonate (PC) and polymethylmethacrylate (PMMA) have been obtained by the layer multiplying coextrusion method. Each sample (1024 layers, of equal thickness, with individual thickness between 10 and 200 nm) has been investigated at room temperature by Wide Angle X-Ray Scattering (WAXS) using a Bruker Discovery 8 spectrometer (Cu K ? radiation), Raman spectroscopy (Bruker Senterra confocal Raman spectrometer operating at 785 nm), FTIR spectroscopy (Tensor 27 Bruker), and UV-Vis spectroscopy. Further details about the glass transition temperature in these samples have been obtained by Dynamical Mechanical Analysis, DMA, (TA Instruments Q800) at various frequencies in the range 1 to 100 Hz. Isothermal Differential Scanning Calorimetry, DSC, (TA Instruments Q200) was used to investigate the effect of the thickness of the polymeric film on the crystallization processes. Non-isothermal DSC measurements aimed at the identification and location of the main phase transitions (glass, crystallization, and melting) occurring in these multilayers. The effects of confinement on the phase transitions occurring in these multilayers are discussed in detail.

  19. Heat Transfer in High Temperature Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Miller, Steve D.; Cunnington, George R.

    2007-01-01

    High temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.

  20. 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.

  1. Quantum Spin Hall phase in multilayer graphene

    NASA Astrophysics Data System (ADS)

    Garcia, Noel; Lado, Jose Luis; Fernandez-Rossier, Joaquin; Theory of Nanostructures Team

    2015-03-01

    We address the question of whether multilayer graphene systems are Quantum Spin Hall (QSH) insulators. Since interlayer coupling coples pz orbitals to s orbitals of different layers and Spin-Orbit (SO) couples pz orbitals with px and py of opposite spins, new spins mixing channels appear in the multilayer scenario that were not present in the monolayer. These new spin-mixing channels cast a doubt on the validity of the spin-conserving Kane-Mele model for multilayers and motivates our choice of a four orbital tight-binding model in the Slater-Koster approximation with intrinsic Spin-Orbit interaction. To completely determine if the QSH phase is present we calculate for different number of layers both the Z2 invariant for different stackings (only for inversion symmetric systems), and the density of states at the edge of semi-infinite graphene ribbon with armchair termination. We find that systems with even number of layers are normal insulators while systems with odd number of layers are QSH insulators, regardless of the stacking. We acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH.

  2. 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.

  3. Multiperiodicity in plasmonic multilayers: General description and diversity of topologies

    NASA Astrophysics Data System (ADS)

    Orlov, Alexey A.; Krylova, Anastasia K.; Zhukovsky, Sergei V.; Babicheva, Viktoriia E.; Belov, Pavel A.

    2014-07-01

    We introduce multiperiodicity in periodic metal-dielectric multilayers by stacking more than two types of metal and/or dielectric layers into the unit cell. A simple way to characterize arbitrary multiperiodic multilayers using permutation vectors is suggested and employed. Effects of multiperiodicity up to its fourth order are investigated. We demonstrate that various topologies of multiple-sheet isofrequency and dispersion surfaces exist for such plasmonic multilayers, including a photonic realization of nontrivial isolated Dirac cones.

  4. 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.

  5. Etched-multilayer phase shifting masks for EUV lithography

    DOEpatents

    Chapman, Henry N.; Taylor, John S.

    2005-04-05

    A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.

  6. 77 FR 45336 - Multilayered Wood Flooring From the People's Republic of China: Initiation of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-31

    ...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...antidumping duty order on multilayered wood flooring from the People's Republic of...antidumping duty order on multilayered wood flooring from the PRC was published...

  7. 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

    ...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of...initiated an investigation of multilayered wood flooring from the People's Republic of China (``PRC''). See Multilayered Wood Flooring From the People's Republic...

  8. 76 FR 13357 - Multilayered Wood Flooring from the People's Republic of China: Postponement of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ...Administration [A-570-970] Multilayered Wood Flooring from the People's Republic of...antidumping duty investigation on multilayered wood flooring from the People's Republic of...1\\ See Multilayered Wood Flooring from the People's Republic...

  9. 78 FR 32367 - Multilayered Wood Flooring From the People's Republic of China; Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-30

    ...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of...antidumping duty order on multilayered wood flooring (``MLWF'') from the People's...Duty New Shipper Review: Multilayered Wood Flooring from the People's Republic...

  10. Unsupervised Hebbian learning by recurrent multilayer neural networks for temporal hierarchical pattern recognition

    E-print Network

    Rathinam, Muruhan

    ­unsupervised learning; learning machine; recurrent neural network; Hebbian learning; multilayer neural networkUnsupervised Hebbian learning by recurrent multilayer neural networks for temporal hierarchical learning are two essential features of biological neural networks. An arti...cial recurrent multilayer

  11. 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

  12. Near-field optical properties of multilayer ridge metal/multilayer-dielectric gratings for pulse compressor

    NASA Astrophysics Data System (ADS)

    Guana, Heyuan; Huang, Chenze; Chen, Zhe; Jin, Yunxia; Yi, Kui; Shao, Jianda

    2015-07-01

    The multilayer ridge metal/multilayer-dielectric gratings (MMDGs) for pulse compressors show high efficiency, broad bandwidths, large fabrication tolerances and high laser-induced damage thresholds. The diffraction efficiency, bandwidth, and near-field distribution of the multilayer structure ridge MMDG are theoretically investigated. Simulation results show that the film structure of the grating ridge has a great influence on the bandwidth and near-field distribution. The maximum electric field is located in the high-index layer of the grating ridge with high -1st diffraction efficiency. As the thickness of the high-index layer decreases, the maximum electric field moves to the low-index layer of the grating ridge with. Base on the results, the sandwich ridge MMDG is an ideal pulse compression grating for chirped pulse amplification systems.

  13. Stable multilayer thin films composed of gold nanoparticles and lysozyme

    NASA Astrophysics Data System (ADS)

    Su, Yan-lei; Li, Chao

    2008-01-01

    It needs appropriately attractive forces to construct multilayer thin films by layer-by-layer (LBL) assembly technique. It is feasible to prepare multilayer thin films on glass slides with negatively charged gold nanoparticles and positively charged lysozyme through the electrostatic LBL assembly technique. The gold nanoparticles/lysozyme multilayer thin films are highly stable; immersion in 0.1 M HCl, NaOH, and surfactant sodium dodecyl sulfate aqueous solutions cannot destroy the films. The highly stable gold nanoparticles/lysozyme multilayer thin films have potential application in long-term antibacterial coating.

  14. Soft X-UV silver silicon multilayer mirrors

    NASA Astrophysics Data System (ADS)

    Shao, Jian-Da; Fan, Zhengxiu; Guo, Yong H.; Jin, Lei

    1991-11-01

    In the soft x-ray domain (near 10 nm), the reported optical constants of silver and silicon are sufficiently different to make them attractive for a multilayer design. In this paper, design and fabrication of silver/silicon multilayer to be used as normal-incidence reflectors for 11.4 nm radiation are presented. Characterization of these multilayer structures was accomplished using Auger electron spectroscopy (AES) and little-angle x-ray diffraction (LXD). As a result of our experiments, we came to realize that silver/silicon multilayer can provide high quality structures and reach a certain reflectance.

  15. 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. ...

  16. Mechanics of nanoscale composite films from stress-electrical measurements: A nanoscale foam

    NASA Astrophysics Data System (ADS)

    Nguyen, Chieu; Maheshwari, Vivek; Saraf, Ravi

    2009-03-01

    Nanometer thin (> 100nm) composite films consisting of polymers and organic-inorganic materials such as nanoparticles, quantum dots, nanotubes and dyes are widely researched for applications in designing a bio-mimetic cell membrane, solar cells, electronic and optical sensors, ion separation membranes and coatings. Being nanoscale in dimensions the mechanical properties of the film is critically governed by its morphology at nanoscale and the mutual interaction between the constituents of the film. The assembly process and the components of the film are detrimental in defining its morphology. A vast array of film morphologies is possible due to the multitude of combinations in processing and the components available to make the film. The study of mechanical properties of the film is hence important due their application in multitude of fields and correlating it to the nanoscale morphology and properties of its constituents. Here we present the stress-electrical measurements on a nanoscale (˜100nm) nanocomposite film prepared using the well known spin assisted ionic self-assembly process. The film is a stack of nanoparticle layers, spaced by dielectric layer. Each dielectric layer consists of a stack of alternating anionic and cationic polyelectrolyte layers. The separation between the nanoparticle layers can be controlled with nanometer scale precession by modulating the number of polyelectrolyte layers in each dielectric layer.

  17. Reactive Functionalized Multilayer Polymers in Coextrusion Process

    NASA Astrophysics Data System (ADS)

    Lamnawar, Khalid; Maazouz, Abderrahim

    2007-04-01

    Coextrusion technologies are commonly used to produce multilayered composite sheets or films with a large range of applications. The contrast of rheological properties between layers can lead to interfacial instabilities during flow. Important theoretical and experimental advances have been made during the last decades on the stability of compatible and incompatible polymers using a mechanical approach. The present study deals with the influence of this affinity on interfacial instabilities for functionalized incompatible polymers between the neighboring layers. Polyamide (PA6)/Polyethylene-grafted (GMA) or pure PE were studied with different viscosity and elasticity ratios. We have experimentally confirmed, in this case, that the weak disturbance can be predicted by considering an interphase of non-zero thickness (corresponding to interdiffusion/reaction zone) instead of a purely geometrical interface between the two reactive layers. As a first step, rheological behavior of multilayer coextruded cast films was investigated to probe: (i) the competition between polymer/polymer interdiffusion and the interfacial reaction and (ii) the influence of the interphase. The contribution of this one effect has been studied along with the increase of the number of layers. The results show that the variation in dynamic modulus of the multilayer system reflects both diffusion and chemical reaction. Finally, and in order to quantify the contribution of the effect of the interface/interphase with a specific interfacial area, an expression was developed to take into account the interphase triggered between the neighboring layers and allowed us to estimate its thickness at a specific welding time and shear rate. As the second step, we formulate an experimental strategy to optimize the process by listing the different parameters controlling the stability of the reactive multilayer flows. The plastic films of two, three and five layers were coextruded in symmetrical and asymmetrical configurations in which PA6 is a middle layer. Indeed, for reactive multilayered system, the interfacial flow instability can be reduced or eliminated, for example, by (i) increasing the residence time or temperature in the coextrusion feed block (for T over reaction temperature) and (ii) reducing the total extrusion flow rate. Hence, based on this analysis guide-lines for stable Coextrusion of reactive functionalized polymers can be provided.

  18. 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

  19. Attosecond nanoscale near-field sampling

    E-print Network

    Förg, Benjamin; Suessmann, Frederik; Foerster, Michael; Krueger, Michael; Ahn, Byung-Nam; Wintersperger, Karen; Zherebtsov, Sergey; Guggenmos, Alexander; Pervak, Vladimir; Kessel, Alexander; Trushin, Sergei; Azzeer, Abdallah; Stockman, Mark; Kim, Dong-Eon; Krausz, Ferenc; Hommelhoff, Peter; Kling, Matthias

    2015-01-01

    The promise of ultrafast light field driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical nearfields from light interaction with nanostructures with sub cycle resolution. Here, we experimentally demonstrate attosecond nearfield retrieval with a gold nanotip using streaking spectroscopy. By comparison of the results from gold nanotips to those obtained for a noble gas, the spectral response of the nanotip near field arising from laser excitation can be extracted. Monte Carlo MC trajectory simulations in near fields obtained with the macroscopic Maxwells equations elucidate the streaking mechanism on the nanoscale.

  20. Nanoscale Sensing with Nitrogen Vacancy Centers

    NASA Astrophysics Data System (ADS)

    Urbach, Elana; Lovchinsky, Igor; Sushkov, Alex; Park, Hongkun; Lukin, Mikhail

    2015-05-01

    In the last several decades Magnetic resonance imaging (MRI) has emerged as a powerful tool in science and technology. Conventional MRI technology, however, relies on measuring magnetic fields from a large (macroscopic) number of molecules, for example tissues in specific areas of the brain. Extending these techniques to the nanoscale could enable revolutionary advances in the physical, biological and medical sciences. Here we report on recent progress in using Nitrogen-Vacancy (NV) centers in diamond to detect small numbers of nuclear spins in biological molecules. In particular, we have demonstrated detection of single proteins attached to the diamond surface.

  1. 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.

  2. 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.

  3. Size-Dependent Accuracy of Nanoscale Thermometers.

    PubMed

    Alicki, Robert; Leitner, David M

    2015-07-23

    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

  4. Nanoscale growth twins in sputtered metal films

    SciTech Connect

    Misra, Amit; Anderoglu, Osman; Hoagland, Richard G; Zhang, X

    2008-01-01

    We review recent studies on the mechanical properties of sputtered Cu and 330 stainless steel films with {l_brace}1 1 1{r_brace} nanoscale growth twins preferentially oriented perpendicular to growth direction. The mechanisms of formation of growth twins during sputtering and the deformation mechanisms that enable usually high strengths in nanotwinned structures are highlighted. Growth twins in sputtered films possess good thermal stability at elevated temperature, providing an approach to extend the application of high strength nanostructured metals to higher temperatures.

  5. Nanoscale investigation of organic - inorganic halide perovskites

    NASA Astrophysics Data System (ADS)

    Cacovich, S.; Divitini, G.; Vru?ini?, M.; Sadhanala, A.; Friend, R. H.; Sirringhaus, H.; Deschler, F.; Ducati, C.

    2015-10-01

    Over the last few years organic - inorganic halide perovskite-based solar cells have exhibited a rapid evolution, reaching certified power conversion efficiencies now surpassing 20%. Nevertheless the understanding of the optical and electronic properties of such systems on the nanoscale is still an open problem. In this work we investigate two model perovskite systems (based on iodine - CH3NH3PbI3 and bromine - CH3NH3PbBr3), analysing the local elemental composition and crystallinity and identifying chemical inhomogeneities.

  6. Long Range Interactions in Nanoscale Science

    SciTech Connect

    French, Roger H; Parsegian, V Adrian; Podgonik, Rudolph; Rajter, Rick; Jagota, Anand; Luo, Jian; Asthagiri, Dilip; Chaudhury, Manoj; Chiang, Yet-Ming; Granick, Steve; Kalinin, Sergei V; Kardar, Mehran; Kjellander, Roland; Langreth, David C.; Lewis, Jennifer; Lustig, Steve; Wesolowski, David J; Wettlaufer, John; Ching, Wai-Yim; Finnis, Mike; Houlihan, Frank; Von Lilienfeld, O. Anatole; Van Oss, Carel; Zemb, Thomas

    2010-01-01

    Our understanding of the long range electrodynamic, electrostatic, and polar interactions that dominate the organization of small objects at separations beyond an interatomic bond length is reviewed. From this basic-forces perspective, a large number of systems are described from which one can learn about these organizing forces and how to modulate them. The many practical systems that harness these nanoscale forces are then surveyed. The survey reveals not only the promise of new devices and materials, but also the possibility of designing them more effectively.

  7. Field limit and nano-scale surface topography of superconducting radio-frequency cavity made of extreme type II superconductor

    NASA Astrophysics Data System (ADS)

    Kubo, Takayuki

    2015-06-01

    The field limit of a superconducting radio-frequency cavity made of a type II superconductor with a large Ginzburg-Landau parameter is studied, taking the effects of nano-scale surface topography into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for an ideal flat surface and a suppression factor that contains the effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors is derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by electropolishing is evaluated by using results of surface topographic study. The estimated field limit is consistent with the present record field of nitrogen-doped Nb cavities. Suppression factors of surfaces of other bulk and multilayer superconductors, and those after various surface processing technologies, can also be evaluated by using the formula.

  8. A mesoscopic description of radiative heat transfer at the nanoscale

    E-print Network

    Svend-Age Biehs; Emmanuel Rousseau; Jean-Jacques Greffet

    2011-03-11

    We present a formulation of the nanoscale radiative heat transfer (RHT) using concepts of mesoscopic physics. We introduce the analog of the Sharvin conductance using the quantum of thermal conductance. The formalism provides a convenient framework to analyse the physics of RHT at the nanoscale. Finally, we propose a RHT experiment in the regime of quantized conductance.

  9. Fabrication of Nanoscale Circuits on Inkjet-Printing Patterned Substrates.

    PubMed

    Chen, Shuoran; Su, Meng; Zhang, Cong; Gao, Meng; Bao, Bin; Yang, Qiang; Su, Bin; Song, Yanlin

    2015-07-01

    Nanoscale circuits are fabricated by assembling different conducting materials (e.g., metal nanoparticles, metal nano-wires, graphene, carbon nanotubes, and conducting polymers) on inkjet-printing patterned substrates. This non-litho-graphy strategy opens a new avenue for integrating conducting building blocks into nanoscale devices in a cost-efficient manner. PMID:26011403

  10. 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

  11. 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…

  12. Nano-Scale Mechanics of Nanotubes, Nanowires, and Nanobelts**

    E-print Network

    Wang, Zhong L.

    Nano-Scale Mechanics of Nanotubes, Nanowires, and Nanobelts** By Zhong L. Wang,* Rui Ping Gao importance to space technology. Nano- wires may serve as the interconnects and devices for nanoe- lectronics and optoelectronics.[2] Searching for interconnects is the key for quantum devices and nano-scale system inte- gration

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

    EPA Science Inventory

    Cover of the <span class=Nanoscale Silver Final report"> This final report presents a case study of engineered nanoscale silver (nano-Ag), focusing on...

  14. Effective dechlorination of HCB by nanoscale Cu/Fe particles.

    PubMed

    Zhu, Nairuo; Luan, Hongwei; Yuan, Songhu; Chen, Jing; Wu, Xiaohui; Wang, Linling

    2010-04-15

    We previously reported that microscale Cu/Fe bimetal could be used for the dechlorination of hexachlorobenzene (HCB), a representative polychlorinated persistent organic pollutant (POPs). But slow reduction rate and rather incomplete dechlorination were reached. In this study, HCB dechlorination by nanoscale Fe and Cu/Fe was evaluated. It was found that HCB reduction by nanoscale Fe was rather slow, and the reduction was significantly increased by nanoscale Cu/Fe. Near complete reduction of HCB was obtained by nanoscale Cu/Fe for 48 h treatment. HCB was quickly dechlorinated to PeCB, TeCBs, TCBs and DCBs without selectivity via a stepwise process. The reduction rate and dechlorination extent were much higher compared with microscale Cu/Fe. Lowering pH during reduction showed slightly negative influence on HCB reduction by nanoscale Cu/Fe due to retarded co-precipitation. A catalytic hydrogenation process on Cu surface through iron oxide film was suggested for the increased HCB reduction by Cu coating on nanoscale Fe. This study proved that using a much cheaper bimetallic iron of nanoscale Cu/Fe than nanoscale Pd/Fe could also achieve the effective dechlorination of HCB. PMID:19969417

  15. Room-temperature stabilization of nanoscale superionic Ag2Se

    E-print Network

    Room-temperature stabilization of nanoscale superionic Ag2Se T Hu1,2 , J S Wittenberg2 and A M the nanoscale size-dependence of the Ag2Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear

  16. www.rsc.org/nanoscale ISSN 2040-3364

    E-print Network

    Lin, Zhiqun

    , thermoelec- tric, ferroelectric, piezoelectric, and dielectric devices.1­3 In particular, perovskiteNanoscale www.rsc.org/nanoscale ISSN 2040-3364 PAPER Lin, Lin et al. Garden-like perovskite-like perovskite superstructures with enhanced photocatalytic activity Meidan Ye,ab Mengye Wang,ab Dajiang Zheng

  17. 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…

  18. 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.

  19. Polyelectrolyte multilayer-assisted fabrication of non-periodic silicon nanocolumn substrates for cellular interface applications

    NASA Astrophysics Data System (ADS)

    Lee, Seyeong; Kim, Dongyoon; Kim, Seong-Min; Kim, Jeong-Ah; Kim, Taesoo; Kim, Dong-Yu; Yoon, Myung-Han

    2015-08-01

    Recent advances in nanostructure-based biotechnology have resulted in a growing demand for vertical nanostructure substrates with elaborate control over the nanoscale geometry and a high-throughput preparation. In this work, we report the fabrication of non-periodic vertical silicon nanocolumn substrates via polyelectrolyte multilayer-enabled randomized nanosphere lithography. Owing to layer-by-layer deposited polyelectrolyte adhesives, uniformly-separated polystyrene nanospheres were securely attached on large silicon substrates and utilized as masks for the subsequent metal-assisted silicon etching in solution. Consequently, non-periodic vertical silicon nanocolumn arrays were successfully fabricated on a wafer scale, while each nanocolumn geometric factor, such as the diameter, height, density, and spatial patterning, could be fully controlled in an independent manner. Finally, we demonstrate that our vertical silicon nanocolumn substrates support viable cell culture with minimal cell penetration and unhindered cell motility due to the blunt nanocolumn morphology. These results suggest that vertical silicon nanocolumn substrates may serve as a useful cellular interface platform for performing a statistically meaningful number of cellular experiments in the fields of biomolecular delivery, stem cell research, etc.Recent advances in nanostructure-based biotechnology have resulted in a growing demand for vertical nanostructure substrates with elaborate control over the nanoscale geometry and a high-throughput preparation. In this work, we report the fabrication of non-periodic vertical silicon nanocolumn substrates via polyelectrolyte multilayer-enabled randomized nanosphere lithography. Owing to layer-by-layer deposited polyelectrolyte adhesives, uniformly-separated polystyrene nanospheres were securely attached on large silicon substrates and utilized as masks for the subsequent metal-assisted silicon etching in solution. Consequently, non-periodic vertical silicon nanocolumn arrays were successfully fabricated on a wafer scale, while each nanocolumn geometric factor, such as the diameter, height, density, and spatial patterning, could be fully controlled in an independent manner. Finally, we demonstrate that our vertical silicon nanocolumn substrates support viable cell culture with minimal cell penetration and unhindered cell motility due to the blunt nanocolumn morphology. These results suggest that vertical silicon nanocolumn substrates may serve as a useful cellular interface platform for performing a statistically meaningful number of cellular experiments in the fields of biomolecular delivery, stem cell research, etc. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02384j

  20. Probing Nanoscale Thermal Transport in Surfactant Solutions.

    PubMed

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B; Qiao, Rui; Yang, Bao

    2015-01-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient. PMID:26534840

  1. Viscosity measurements of nanoscale liquid films

    NASA Astrophysics Data System (ADS)

    Kramkowski, Edward; Wilson, David; Khan, Shah; Mukhopadhyay, Ashis; Hoffmann, Peter

    2013-03-01

    Measuring the viscosity of nanoscale films of liquids can be quite challenging. This difficulty has resulted in contradictory claims regarding the change in viscosity upon nanoscale confinement of liquids. Recently, we showed through a careful analysis, that in weakly interacting liquids, such as non-polar oils, the viscosity seems unchanged from the bulk value even under extreme confinement down to just a few molecular layers. Moreover, above a critical shear rate, shear thinning is observed. These measurements also have practical significance, in that traditional methods for characterizing the viscosity of solutions, while accurate, require the use of a few grams of the material being investigated. As the production methods of prototype materials becomes more costly, devising techniques that can accurately measure physical properties with much smaller volumes of material would be highly desirable. To this end, we aim to design a quick, reliable, and cost-effective method of measuring viscosity through the use of an atomic force microscope, which requires only nanograms of the sample being tested. Here we will introduce preliminary results, comparing the AFM-determined viscosity with values attained through the use of other commonly used measurement devices.

  2. Nanoscale Impedance Imaging of Novel Quantum Materials

    NASA Astrophysics Data System (ADS)

    Lai, Keji

    2015-03-01

    The research of complex quantum materials, in which a dazzling number of emergent phenomena take place in the nanoscale, is a major theme in modern condensed matter physics. For real-space mapping of complex systems, electrical impedance microscopy fills an important void that is not well represented by the existing local probes. Using shielded cantilever probes and sensitive microwave electronics, we can now perform non-invasive electrical imaging with unprecedented resolution (10-100nm) and sensitivity (sub-aF). To date, this powerful technique has enabled us to visualize the electronic inhomogeneity in colossal magnetoresistance manganites, spatially resolve the topological edge channels, image the metal-insulator transition in novel field-effect transistors, and probe the anomalous conduction in multiferroic domain walls. The sub-surface imaging capability is also ideal for understanding the evolution of chemical reaction involving low-dimensional layered materials. Further development of the technique will allow us to perform local dielectric spectroscopy across a large frequency span, explore the localized microwave magnetic resonance, and study the nanoscale nonlinear electromagnetic response in complex materials.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Synthesis and properties of nanoscale titanium boride

    NASA Astrophysics Data System (ADS)

    Efimova, K. A.; Galevskiy, G. V.; Rudneva, V. V.

    2015-09-01

    This work reports the scientific and technological grounds for plasma synthesis of titanium diboride, including thermodynamic and kinetic conditions of boride formation when titanium and titanium dioxide are interacting with products resulting from boron gasification in the nitrogen - hydrogen plasma flow, and two variations of its behavior using the powder mixtures: titanium - boron and titanium dioxide - boron. To study these technology variations, the mathematical models were derived, describing the relation between element contents in the synthesized products of titanium and free boron and basic parameters. The probable mechanism proposed for forming titanium diboride according to a "vapour - melt - crystal" pattern was examined, covering condensation of titanium vapour in the form of aerosol, boriding of nanoscale melt droplets by boron hydrides and crystallization of titanium - boron melt. The comprehensive physical - chemical certification of titanium diboride was carried out, including the study of its crystal structure, phase and chemical composition, dispersion, morphology and particle oxidation. Technological application prospects for use of titanium diboride nanoscale powder as constituent element in the wettable coating for carbon cathodes having excellent physical and mechanical performance and protective properties.

  8. Structure of nanoscale gas bubbles in metals

    SciTech Connect

    Caro, A. Schwen, D.; Martinez, E.

    2013-11-18

    A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2?/R, with ? the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1?nm and below.

  9. Probing Nanoscale Thermal Transport in Surfactant Solutions

    PubMed Central

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B.; Qiao, Rui; Yang, Bao

    2015-01-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient. PMID:26534840

  10. Convex Lens-Induced Nanoscale Templating

    NASA Astrophysics Data System (ADS)

    Berard, Daniel; Michaud, Francois; McFaul, Christopher; Mahsid, Sara; Reisner, Walter; Leslie, Sabrina

    2014-03-01

    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 actively transforming a macroscale flow-cell into a nanofluidic device without need for high-temperature direct bonding, leading to ease of sample loading and greater accessibility of the surface. Moreover, as DNA molecules present in the gap will be driven into the embedded topography from above, CLINT eliminates the need for the high pressures or electric fields necessitated by direct bonded nanofluidic devices for loading DNA in the confined structures. To demonstrate the versatility of CLINT, we confine DNA to nanogroove structures, demonstrating DNA nanochannel-based stretching. Using ionic strengths that are in line with typical biological buffers, we have successfully extended DNA in sub 30nm nanochannels, achieving high stretching (90%) that is in good agreement with Odijk deflection theory.

  11. Probing Nanoscale Thermal Transport in Surfactant Solutions

    NASA Astrophysics Data System (ADS)

    Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B.; Qiao, Rui; Yang, Bao

    2015-11-01

    Surfactant solutions typically feature tunable nanoscale, internal structures. Although rarely utilized, they can be a powerful platform for probing thermal transport in nanoscale domains and across interfaces with nanometer-size radius. Here, we examine the structure and thermal transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane liquids using small-angle neutron scattering, thermal conductivity measurements, and molecular dynamics simulations. We report the first experimental observation of a minimum thermal conductivity occurring at the critical micelle concentration (CMC): the thermal conductivity of the surfactant solution decreases as AOT is added till the onset of micellization but increases as more AOT is added. The decrease of thermal conductivity with AOT loading in solutions in which AOT molecules are dispersed as monomers suggests that even the interfaces between individual oleophobic headgroup of AOT molecules and their surrounding non-polar octane molecules can hinder heat transfer. The increase of thermal conductivity with AOT loading after the onset of micellization indicates that the thermal transport in the core of AOT micelles and across the surfactant-oil interfaces, both of which span only a few nanometers, are efficient.

  12. Nanoscale Fluid Mechanics and Energy Conversion

    SciTech Connect

    Chen, X; Xu, BX; Liu, L

    2014-05-29

    Under nanoconfinement, fluid molecules and ions exhibit radically different configurations, properties, and energetics from those of their bulk counterparts. These unique characteristics of nanoconfined fluids, along with the unconventional interactions with solids at the nanoscale, have provided many opportunities for engineering innovation. With properly designed nanoconfinement, several nanofluidic systems have been devised in our group in the past several years to achieve energy conversion functions with high efficiencies. This review is dedicated to elucidating the unique characteristics of nanofluidics, introducing several novel nanofluidic systems combining nanoporous materials with functional fluids, and to unveiling their working mechanisms. In all these systems, the ultra-large surface area available in nanoporous materials provides an ideal platform for seamlessly interfacing with nanoconfined fluids, and efficiently converting energy between the mechanical, thermal, and electrical forms. These systems have been demonstrated to have great potentials for applications including energy dissipation/absorption, energy trapping, actuation, and energy harvesting. Their efficiencies can be further enhanced by designing efforts based upon improved understanding of nanofluidics, which represents an important addition to classical fluid mechanics. Through the few systems exemplified in this review, the emerging research field of nanoscale fluid mechanics may promote more exciting nanofluidic phenomena and mechanisms, with increasing applications by encompassing aspects of mechanics, materials, physics, chemistry, biology, etc.

  13. Effect of Different TiO2-SiO2 Multilayer Coatings Applied by Sol-Gel Method on Antireflective Property

    NASA Astrophysics Data System (ADS)

    lari, Najme; Ahangarani, Shahrokh; Shanaghi, Ali

    2015-07-01

    Multilayer thin films prepared using the sol-gel process have been used in many antireflection applications. In this paper, antireflective nanoscale multilayer TiO2-SiO2 coatings were formed on both sides of the glass substrates by combining sol-gel method and dip coating techniques. The coatings were carried out using tetraethyl orthosilicate as precursor for SiO2 and tetrabutyl orthotitanate as precursor for TiO2. The coatings prepared in this work were characterized using scanning electron microscope, Fourier-transformed infrared spectrophotometer and UV-Visible spectrophotometer. The SiO2 top layer coatings showed excellent antireflection in the wavelength range of 400-800 nm where the transmittance of glass substrate is significantly lower. By increasing the number of double TiO2-SiO2 layers, the transmission of the coated glasses increased due to applied multilayer coating properties. Six-layer sol-gel TiO2-SiO2 coatings showed the highest visible transmittance about 99.25% at the band of 550-650 nm.

  14. Synergy Landscapes: A Multilayer Network for Collaboration in Biological Research

    E-print Network

    Newberg, Heidi

    Synergy Landscapes: A Multilayer Network for Collaboration in Biological Research Konstantin Kuzmin of research. This multilayer network that we call Synergy Landscapes will allow us to identify broad patterns Landscapes also will dynamically track research trends in a customized framework that informs scientists

  15. RUBIDIUM VAPOR CELL WITH INTEGRATED NONMETALLIC MULTILAYER REFLECTORS

    E-print Network

    Chen, Zhongping

    RUBIDIUM VAPOR CELL WITH INTEGRATED NONMETALLIC MULTILAYER REFLECTORS M.A. Perez1 , U. Nguyen2 , S integrated in rubidium vapor cells. A hybrid bulk micromachining and multilayer thin film process is used micromachined angled silicon reflectors within a rubidium vapor cell for routing laser light through the cell

  16. 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.

  17. Multi-layer laminate structure and manufacturing method

    DOEpatents

    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.

  18. 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 of the number of hidden units. New training algorithms are developed where weights and thresholds from a well-trained

  19. 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 ...

  20. Prediction of pressure during evacuation of multilayer insulation.

    NASA Technical Reports Server (NTRS)

    Glassford, A. P. M.

    1972-01-01

    Description of an improved analytical procedure for predicting the pressure time history during evacuation of multilayer-insulation thermal-protection systems. To evaluate the performance of the proposed analysis and to demonstrate its usefulness as a design tool, a comparison is presented of the experimentally measured and predicted evacuation pressure histories for a laboratory-scale model multilayer insulation blanket.

  1. MULTILAYER PARYLENE-C STENCILS FOR DYNAMICALLY CONTROLLING CELL INTERACTIONS

    E-print Network

    Dokmeci, Mehmet

    MULTILAYER PARYLENE-C STENCILS FOR DYNAMICALLY CONTROLLING CELL INTERACTIONS C.-L. Chen1 , S. Jinno-vitro. In this study, we describe a technology for creating multilayer and mechanically robust parylene-C stencils and fibronectin, both untreated and detergent treated Parylene surfaces is rendered adhesive for cells. Co

  2. MULTILAYER PARYLENE-C STENCILS FOR DYNAMICALLY CONTROLLING CELL INTERACTIONS

    E-print Network

    Dokmeci, Mehmet

    MULTILAYER PARYLENE-C STENCILS FOR DYNAMICALLY CONTROLLING CELL INTERACTIONS C.-L. Chen1 , S. Jinno-vitro. In this study, we describe a technology for creating multilayer and mechanically robust parylene-C stencils and fibronectin, both untreated and anti-stiction layer treated parylene-C surfaces are rendered adhesive

  3. 78 FR 30329 - Multilayered Wood Flooring from China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ... took effect on November 7, 2011. See 76 FR 61937 (Oct. 6, 2011) and the newly revised Commission... COMMISSION Multilayered Wood Flooring from China AGENCY: United States International Trade Commission. ACTION... and 731-TA-1179 (Final) concerning multilayered wood flooring (``MLWF'') from China. For...

  4. 75 FR 79019 - Multilayered Wood Flooring From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-17

    ... the notice in the Federal Register of October 27, 2010 (75 FR 66126). The conference was held in... Multilayered Wood Flooring From China Determinations On the basis of the record \\1\\ developed in the subject... imports from China of multilayered wood flooring, provided for in subheadings 4409.10, 4409.29,...

  5. 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.; Hasyareeda, N.

    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.

  6. Improved multilayer insulation applications. [spacecraft thermal control

    NASA Technical Reports Server (NTRS)

    Mikk, G.

    1982-01-01

    Multilayer insulation blankets used for the attenuation of radiant heat transfer in spacecraft are addressed. Typically, blanket effectiveness is degraded by heat leaks in the joints between adjacent blankets and by heat leaks caused by the blanket fastener system. An approach to blanket design based upon modular sub-blankets with distributed seams and upon an associated fastener system that practically eliminates the through-the-blanket conductive path is described. Test results are discussed providing confirmation of the approach. The specific case of the thermal control system for the optical assembly of the Space Telescope is examined.

  7. Oscillating magnetocaloric effect of a multilayer graphene

    SciTech Connect

    Alisultanov, Z. Z.; Paixão, L. S.; Reis, M. S.

    2014-12-08

    The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.

  8. 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.

  9. 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.

  10. Engineering aspects of multilayer piezoceramic actuators

    NASA Astrophysics Data System (ADS)

    Golovnin, V. A.; Kaplunov, I. A.; Ivanova, A. I.; Grechishkin, R. M.

    2013-12-01

    With the increasing demand for multilayer ceramic chip components a full understanding of the co-firing of ceramics with metal electrodes becomes important. In the present work the processing of a piezoelectric monolithic actuator by stacking and cofiring Ag-Pd electroded tape cast layers was studied. The inter-diffusion and microstructure of the co-fired interface of PZT ferroelectrics and Ag-Pd metal electrode were examined by scanning electron microscopy (SEM) and energy-dispersive microanalysis. No strong structural distortions and interdiffusion were observed at the co-fired ceramic-electrode interface.

  11. Magnetoelectronic properties of multilayer black phosphorus

    NASA Astrophysics Data System (ADS)

    Jiang, Yongjin; Roldán, Rafael; Guinea, Francisco; Low, Tony

    2015-08-01

    We examine the electronic properties of two-dimensional electron gas in black phosphorus multilayers in the presence of a perpendicular magnetic field, highlighting the role of in-plane anisotropy on various experimental quantities such as ac magnetoconductivity, screening, and magnetoplasmons. We find that resonant structures in the ac conductivity exhibits a redshift with increasing doping due to interband coupling ? . This arises from an extra correction term in the Landau energy spectrum proportional to n2?2 (n is Landau index), up to second order in ? . We found also that Coulomb interaction leads to highly anisotropic magnetoexcitons.

  12. Fractional statistical theory of finite multilayer adsorption

    NASA Astrophysics Data System (ADS)

    Takara, E. A.; Quiroga, E.; Matoz-Fernandez, D. A.; Ochoa, N. A.; Ramirez-Pastor, A. J.

    2016-01-01

    In the present paper, finite multilayer adsorption is described as a fractional statistics problem, based on Haldane's statistics. In this scheme, the Helmholtz free energy and its derivatives are written in terms of a parameter g, which relates to the configuration of the molecules in the adsorbed state. For values of g ranging between 0 and 1 the formalism is used to model experimental data of bovine serum albumin (BSA) adsorbed onto an ion exchange resin for different values of pH and temperature. Excellent agreement between theory and experiments was found.

  13. Digital biomagnetism: Electrodeposited multilayer magnetic barcodes

    NASA Astrophysics Data System (ADS)

    Palfreyman, Justin J.; Cooper, Joshaniel F. K.; van Belle, Frieda; Hong, Bingyan; Hayward, Tom J.; Lopalco, Maria; Bradley, Mark; Mitrelias, Thanos; Bland, J. Anthony C.

    2009-05-01

    A novel magnetic encoding technique for performing high-throughput biological assays is presented. Electrodeposited Ni/Cu and Co/Cu multilayer pillar structures with a diameter of 15 ?m and a thickness up to 10 ?m are presented as "magnetic barcodes", where the number of unique codes possible increases exponentially with a linear increase in length. A gold cap facilitates the growth of self-assembled monolayers (SAMs), while microdrop printing allows efficient generation of large libraries of tagged probes. Coercivity-tuning techniques are used to exploit a non-proximity encoding methodology compatible with microfluidic flow.

  14. Coherent thermal conductance in multilayer photonic crystals

    E-print Network

    Maria Tschikin; Philippe Ben-Abdallah; Svend-Age Biehs

    2012-06-25

    We present an exact calculation of the coherent thermal conductance in a 1-D multilayer photonic crystals (PC) using the S-matrix method. In particular, we study the thermal conductance in a bilayer structure of slabs of Si/vacuum or Al$_2$O$_3$/vacuum by means of the exact expression for the radiative heat flux. We compare our results with results obtained in previous works. Our results show that the coupling of surface modes as well as material losses play a fundamental role in the definition of the thermal conductance of PCs.

  15. Enhanced piezoelectric response in the artificial ferroelectric polymer multilayers

    SciTech Connect

    Zhao, X. L.; Wang, J. L. E-mail: lin-tie@mail.sitp.ac.cn; Tian, B. B.; Liu, B. L.; Wang, X. D.; Sun, S.; Zou, Y. H.; Lin, T. E-mail: lin-tie@mail.sitp.ac.cn; Sun, J. L.; Meng, X. J.; Chu, J. H.

    2014-12-01

    An actuator with a high piezoelectric response, the ferroelectric polymer multilayer actuator, is described. The ferroelectric polymer multilayers consisting of alternative ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofloroethylene) (P(VDF-TrFE-CFE)) terpolymer with different periodicities and fixed total thickness are prepared by the Langmuir-Blodgett technique. Both X-ray diffraction and Raman spectroscopic measurements indicate that the structure of the multilayer with thin alternating layer is similar to that of the ferroelectric copolymer. Compared with that of the copolymer, it is found that the piezoelectric coefficient of the multilayer could be improved by 57%. We attributed the enhanced piezoelectric response of the multilayers to the internal electric fields that arises from the electrostatic couplings between different layers.

  16. Ecological Multilayer Networks: A New Frontier for Network Ecology

    E-print Network

    Pilosof, Shai; Kéfi, Sonia

    2015-01-01

    Networks provide a powerful approach to address myriad phenomena across ecology. Ecological systems are inherently 'multilayered'. For instance, species interact with one another in different ways and those interactions vary spatiotemporally. However, ecological networks are typically studied as ordinary (i.e., monolayer) networks. 'Multilayer networks' are currently at the forefront of network science, but ecological multilayer network studies have been sporadic and have not taken advantage of rapidly developing theory. Here we present the latest concepts and tools of multilayer network theory and discuss their application to ecology. This novel framework for the study of ecological multilayer networks encourages ecologists to move beyond monolayer network studies and facilitates ways for doing so. It thereby paves the way for novel, exciting research directions in network ecology.

  17. 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.

  18. Electrical nanowelding and bottom-up nano-construction together using nanoscale solder.

    PubMed

    Peng, Yong; Cullis, Tony; Inkson, Beverley J

    2010-11-01

    A new bottom-up nanowelding technique enabling the welding of complex 3D nanoarchitectures assembled from individual building blocks using nanovolumes of metal solder is reported in this work. The building blocks of gold nanowires, (Co72Pt28/Pt)n multilayer nanowires, and nanosolder Sn99Au1 alloy nanowires were successfully fabricated by a template technique. Individual metallic nanowires dispersed on Si/SiO2(100 nm) wafers were manipulated and assembled together. Conductive nanostructures were then welded together by the new electrical nanowelding technique using nanovolumes of similar or dissimilar nanosolder. At the weld sites, nanoscale volumes of a chosen metal are deposited using nanosolder of a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. The whole nanowelding process is clean, controllable and reliable, and ensures both mechanically strong and electrically conductive contacts. The quality check of nanoweld achieve a resistance as low as 20 omega by using Sn99Au1 alloy solder. This technique should provide a promising way to conquer the challenge of the integration obstacle for bottom-up nanotechnology. PMID:21137943

  19. 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

  20. 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

  1. Diffusion of Polyelectrolyte Chains within Multilayer Films

    NASA Astrophysics Data System (ADS)

    Sukhishvili, Svetlana; Xu, Li; Zhuk, Aliaksandr; Ankner, John

    2012-02-01

    Using a series of polycations synthesized by atom transfer radical polymerization, we investigate the relative importance of the effects of hydrophobicity, polymer charge density, and steric hindrance to charge pairing on chain dynamics within polyelectrolyte complexes (PECs) and within polyelectrolyte multilayer (PEM) films. First, by applying fluorescence correlation spectroscopy (FCS), ellipsometry and fluorescence recovery after photobleaching (FRAP), we found that the dynamics of chain exchange within PECs is directly correlated with the mode (linear vs. exponential) of PEM film growth. Second, through a combination of neutron reflectometry (NR) and FRAP techniques to the same PEM types, we found that diffusion of polyelectrolyte chains within multilayer films is highly anisotropic, with diffusion coefficients being 10^4-10^5 higher in a direction parallel to the substrate compared to that perpendicular. Chain mobility was also controlled by ionic strength of annealing solutions and steric hindrance to ionic pairing of interacting polyelectrolytes.[4pt] This work was supported by the National Science Foundation under Award DMR-0906474 (S.S.). Neutron measurements were performed at the Spallation Neutron Source at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the DOE under contract No. DE-AC05-00OR22725.

  2. Application of multilayer coatings to replicated substrates

    NASA Astrophysics Data System (ADS)

    Romaine, Suzanne E.; Hussain, Ahsen M.; Everett, J.; Clark, Anna M.; Bruni, Ricardo J.; Gorenstein, Paul; Ghigo, Mauro; Mazzoleni, Franco; Citterio, Oberto; Pedulla, Joseph

    1997-07-01

    We are engaged in a program to develop focusing hard x-ray telescopes in a double conical or Wolter 1 geometry that function up to 100 keV by employing small graze angles and multilayer coatings. Directly polished substrates are not an option because they are too thick to be nested efficiently. The only alternative is to fabricate the very thin substrates by replication. Our objective is the production of integral cylindrical substrates because they should result in better angular resolution than segmented foil geometries. In addition, integral cylinders would be more resistant to possible stress from deep multilayer coatings than segmented ones. Both electroforming of nickel (method of SAX, JET-X, and XMM) and epoxy replication are under consideration. Both processes can utilize the same types of mandrels and separation agents. While electroforming can produce substrates that are thin, the high density of the nickel may result in high weight optics for some missions. For convenience, experimentation with replication and coating is being carried out initially on flats. Our replication studies include trials with gold and carbon separation agents. This paper reports on our efforts with epoxy replicated optics.

  3. Load responsive multilayer insulation performance testing

    SciTech Connect

    Dye, S.; Kopelove, A.; Mills, G. L.

    2014-01-29

    Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

  4. Development of Flexible Multilayer Circuits and Cables

    NASA Technical Reports Server (NTRS)

    Barnes, Kevin N.; Bryant, Robert; Holloway, Nancy; Draughon, Fred

    2005-01-01

    A continuing program addresses the development of flexible multilayer electronic circuits and associated flexible cables. This development is undertaken to help satisfy aerospace-system-engineering requirements for efficient, lightweight electrical and electronic subsystems that can fit within confined spaces, adhere to complexly shaped surfaces, and can be embedded within composite materials. Heretofore, substrate layers for commercial flexible circuitry have been made from sheets of Kapton (or equivalent) polyimide and have been bonded to copper conductors and to other substrate layers by means of adhesives. The substrates for the present developmental flexible circuitry are made from thin films of a polyimide known as LaRC(TM)-SI. This polyimide is thermoplastic and, therefore, offers the potential to eliminate delamination and the need for adhesives. The development work undertaken thus far includes experiments in the use of several techniques of design and fabrication (including computer-aided design and fabrication) of representative flexible circuits. Anticipated future efforts would focus on multilayer bonding, fabrication of prototypes, and overcoming limitations.

  5. Multilayer Nano-Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Yoda, Minami

    2005-11-01

    Nano-particle image velocimetry (nPIV) uses evanescent-wave illumination of fluorescent colloidal tracers to measure the two tangential velocity components u and v averaged over the first 300 nm next to the wall. The evanescent-wave intensity decays exponentially with z, or the distance normal to the wall. Illuminated tracers at smaller z therefore have images that are ``brighter'' than those at larger z. This variation in tracer intensity suggests the possibility of ``multilayer nPIV,'' where u and v are obtained at different z-locations within the first 300 nm next to the wall. The variation of tracer image intensity with distance from the wall is modeled using a basic diffraction optics approach. The tracer images in artificial nPIV images of plane Couette flow for various experimental parameters incorporating hindered Brownian diffusion and image noise were divided into three sub-images, or ``layers,'' based on tracer image intensity. Standard techniques were used to extract average velocities at three different z-locations, with velocity data in the first layer obtained well within 100 nm of the wall. The results demonstrate that multilayer nPIV is feasible if appropriate classification techniques can be determined and used to separate tracer images into different layers.

  6. Multilayer and multiproduct masks: cost reduction methodology

    NASA Astrophysics Data System (ADS)

    Balasinski, Artur P.

    2004-12-01

    The cost of reticles for sub-100 nm technologies is growing twice as fast as the overall cost of new process development. This makes it necessary to pursue mask cost reduction options alternative to the standard approach of one mask for one layer of one product. The several viable scenarios such as the multi-layer or multi-product (shuttle) masks can be identified by a complex technical and economical analysis, to maximize mask return on investment (ROI) over the product lifetime. The key criteria include matching of layers or products on one plate, with respect to the CD and pattern density commonality and the expected time or fab volume to the conversion to solo mask set. This work discusses the business process and the methodology of such analysis. As an example, by taking into account the cost of the exposure and the mask, one can show that for a 100 nm technology, a positive ROI would be achieved for a product or test vehicle with volume below 50 lots utilizing a multi-layer mask set. A more complete study should include considerations of design rules for blading, stepper capacity, product scheduling, yield variation over the wafer, and probability of database updates. These added restrictions limit the benefits of shared mask methodology.

  7. Load responsive multilayer insulation performance testing

    NASA Astrophysics Data System (ADS)

    Dye, S.; Kopelove, A.; Mills, G. L.

    2014-01-01

    Cryogenic insulation designed to operate at various pressures from one atmosphere to vacuum, with high thermal performance and light weight, is needed for cryogenically fueled space launch vehicles and aircraft. Multilayer insulation (MLI) performs well in a high vacuum, but the required vacuum shell for use in the atmosphere is heavy. Spray-on foam insulation (SOFI) is often used in these systems because of its light weight, but can have a higher heat flux than desired. We report on the continued development of Load Responsive Multilayer Insulation (LRMLI), an advanced thermal insulation system that uses dynamic beam discrete spacers that provide high thermal performance both in atmosphere and vacuum. LRMLI consists of layers of thermal radiation barriers separated and supported by micromolded polymer spacers. The spacers have low thermal conductance, and self-support a thin, lightweight vacuum shell that provides internal high vacuum in the insulation. The dynamic load responsive spacers compress to support the external load of a vacuum shell in one atmosphere, and decompress under reduced atmospheric pressure for lower heat leak. Structural load testing was performed on the spacers with various configurations. LRMLI was installed on a 400 liter tank and boil off testing with liquid nitrogen performed at various chamber pressures from one atmosphere to high vacuum. Testing was also performed with an MLI blanket on the outside of the LRMLI.

  8. Polymer multilayer tattooing for enhanced DNA vaccination

    NASA Astrophysics Data System (ADS)

    Demuth, Peter C.; Min, Younjin; Huang, Bonnie; Kramer, Joshua A.; Miller, Andrew D.; Barouch, Dan H.; Hammond, Paula T.; Irvine, Darrell J.

    2013-04-01

    DNA vaccines have many potential benefits but have failed to generate robust immune responses in humans. Recently, methods such as in vivo electroporation have demonstrated improved performance, but an optimal strategy for safe, reproducible, and pain-free DNA vaccination remains elusive. Here we report an approach for rapid implantation of vaccine-loaded polymer films carrying DNA, immune-stimulatory RNA, and biodegradable polycations into the immune-cell-rich epidermis, using microneedles coated with releasable polyelectrolyte multilayers. Films transferred into the skin following brief microneedle application promoted local transfection and controlled the persistence of DNA and adjuvants in the skin from days to weeks, with kinetics determined by the film composition. These ‘multilayer tattoo’ DNA vaccines induced immune responses against a model HIV antigen comparable to electroporation in mice, enhanced memory T-cell generation, and elicited 140-fold higher gene expression in non-human primate skin than intradermal DNA injection, indicating the potential of this strategy for enhancing DNA vaccination.

  9. Simulation of EUV multilayer mirror buried defects

    NASA Astrophysics Data System (ADS)

    Brukman, Matthew J.; Deng, Yunfei; Neureuther, Andrew R.

    2000-07-01

    A new interface has been created to link existing deposition/etching and electromagnetic simulation software, allowing the user to program deposition and etching conditions and then find the reflective properties of the resultant structure. The application studied in this paper is the problem of three-dimensional defects which become buried during fabrication of multilayer mirrors for extreme ultraviolet lithography. The software link reads in surface information in the form of linked triangles, determines all nodes within the triangles, and then creates nodes lying between triangles of different layers to create a 3- dimensional inhomogeneous matrix containing the materials' indices of refraction. This allows etching and depositions to be input into SAMPLE-3D, a multi-surface topology to be generated, and then the electromagnetic properties of the structure to be assessed with TEMPEST. This capability was used to study substrate defects in multilayer mirrors by programming a defect and then sputter-depositing some forty layers on top of the defect. Specifically examined was how the topography depended on sputter conditions and determined the defects' impact on the mirrors' imaging properties. While this research was focused on application to EUV lithography, the general technique may be extended to other optical processes such as alignment and mask defects.

  10. Training multi-layered neural network neocognitron.

    PubMed

    Fukushima, Kunihiko

    2013-04-01

    This paper proposes new learning rules suited for training multi-layered neural networks and applies them to the neocognitron. The neocognitron is a hierarchical multi-layered neural network capable of robust visual pattern recognition. It acquires the ability to recognize visual patterns through learning. For training intermediate layers of the hierarchical network of the neocognitron, we use a new learning rule named add-if-silent. By the use of the add-if-silent rule, the learning process becomes much simpler and more stable, and the computational cost for learning is largely reduced. Nevertheless, a high recognition rate can be kept without increasing the scale of the network. For the highest stage of the network, we use the method of interpolating-vector. We have previously reported that the recognition rate is greatly increased if this method is used during recognition. This paper proposes a new method of using it for both learning and recognition. Computer simulation demonstrates that the new neocognitron, which uses the add-if-silent and the interpolating-vector, produces a higher recognition rate for handwritten digits recognition with a smaller scale of the network than the neocognitron of previous versions. PMID:23380595

  11. Finite element analysis of multilayer coextrusion.

    SciTech Connect

    Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A.; Mrozek, Randy A.; Lenhart, Joseph Ludlow; Rao, Rekha Ranjana; Collins, Robert; Mondy, Lisa Ann

    2011-09-01

    Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

  12. 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.

  13. Carbon-bearing fluids at nanoscale interfaces

    SciTech Connect

    Cole, David; Ok, Salim; Phan, A; Rother, Gernot; Striolo, Alberto; Vlcek, Lukas

    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.

  14. 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.

  15. 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.

  16. Nanoscale defect detection by heterodyne interferometry

    SciTech Connect

    Lin Haoshan; Li Yuhe; Wang Dongsheng; Tong Xiaolei; Liu Mei

    2009-03-10

    We construct an instrument that facilitates the measurement of nanoscale defects. It is based on heterodyne interferometry with phase measurement that utilizes a polarizing beam splitter to form a measuring signal and an oscillating cantilever tip that acts as a scanning probe to get the measurement values of sample topography. The dependence of the tip displacement on the variation of tip-sample distance and the comb scanning of the sample topography are investigated by experiments. The results prove that the tip displacement increases and is enough to be discriminated in various positions where the sample is approached. The system has been successfully utilized to measure the defect characterization by measuring the pitch of the standard sample. The results also show that the heterodyne system has good repeatability, a large measurement range, and high accuracy, with a measurement stability of 0.5 nm.

  17. Identifying nanoscale ferrihydrite in Hydrometallurgical residues

    NASA Astrophysics Data System (ADS)

    Loan, M.; Pierre, T. G. St.; Parkinson, G. M.; Newman, O. G. M.; Farrow, J. B.

    2002-12-01

    The identification of a disordered nanoscale material such as ferrihydrite in a heterogeneous sample environment, as is typically the case in a hydrometallurgical residue, requires a rigorous multifaceted characterization approach. An example of this is the identification of ferrihydrite in paragoethite process residues generated in zinc refining. In a pure-form ferrihydrite, a poorly crystalline iron(III) oxyhydroxide possesses a characteristic powder x-ray diffraction profile consisting of very broad low-intensity reflections. However, in coexistence with crystalline material, the diffraction profile may be masked, lost in the background noise, and easily overlooked. By using several characterization approaches in combination, ferrihydrite can be identified in a hydrometallurgical residue with a higher degree of confidence than can be achieved by the application of a single technique.

  18. Nanoscale characterization of engineered cementitious composites (ECC)

    SciTech Connect

    Sakulich, Aaron Richard 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.

  19. Nanoscale control of phonon excitations in graphene

    PubMed Central

    Kim, Hyo Won; Ko, Wonhee; Ku, JiYeon; Jeon, Insu; Kim, Donggyu; Kwon, Hyeokshin; Oh, Youngtek; Ryu, Seunghwa; Kuk, Young; Hwang, Sung Woo; Suh, Hwansoo

    2015-01-01

    Phonons, which are collective excitations in a lattice of atoms or molecules, play a major role in determining various physical properties of condensed matter, such as thermal and electrical conductivities. In particular, phonons in graphene interact strongly with electrons; however, unlike in usual metals, these interactions between phonons and massless Dirac fermions appear to mirror the rather complicated physics of those between light and relativistic electrons. Therefore, a fundamental understanding of the underlying physics through systematic studies of phonon interactions and excitations in graphene is crucial for realising graphene-based devices. In this study, we demonstrate that the local phonon properties of graphene can be controlled at the nanoscale by tuning the interaction strength between graphene and an underlying Pt substrate. Using scanning probe methods, we determine that the reduced interaction due to embedded Ar atoms facilitates electron–phonon excitations, further influencing phonon-assisted inelastic electron tunnelling. PMID:26109454

  20. 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

  1. 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

  2. Nanoscale design routes to polar oxides

    NASA Astrophysics Data System (ADS)

    Young, Joshua; Rondinelli, James

    2013-03-01

    Many useful material properties, such as ferroelectricity, arise because of inversion symmetry breaking in a material's ground state. Understanding how to purposefully lift spacial parity operations is critical to engineering compounds with `acentric' properties. Using first-principles density functional calculations, we describe the crystal-chemistry criteria necessary to design artificial nanoscale oxides that display spontaneous polarizations using non-polar metal-oxygen polyhedra. By controlling the flavor of A-site cation ordering in AA'B2O6 perovskites, we show that spontaneous electric polarizations comparable in magnitude to conventional ferroelectrics are attainable. We conclude by explaining how the criteria can be extended to other material classes to realize polar oxides by design.

  3. Energy Conversion at Micro and Nanoscale

    NASA Astrophysics Data System (ADS)

    Gammaitoni, Luca

    2014-11-01

    Energy management is considered a task of strategic importance in contemporary society. It is a common fact that the most successful economies of the planet are the economies that can transform and use large quantities of energy. In this talk we will discuss the role of energy with specific attention to the processes that happens at micro and nanoscale. The description of energy conversion processes at these scales requires approaches that go way beyond the standard equilibrium termodynamics of macroscopic systems. In this talk we will address from a fundamental point of view the physics of the dissipation of energy and will focus our attention to the energy transformation processes that take place in the modern micro and nano information and communication devices.

  4. Modular Synthesis of Functional Nanoscale Coordination Polymers

    PubMed Central

    Lin, Wenbin; Rieter, William J.; Taylor, Kathryn M. L.

    2013-01-01

    The coordination-directed assembly of metal ions and organic bridging ligands has afforded a variety of bulk-scale hybrid materials with promising characteristics for a number of practical applications, such as gas storage and heterogeneous catalysis. Recently, so-called coordination polymers have emerged as a new class of hybrid nanomaterials. Herein, we highlight advances in the syntheses of both amorphous and crystalline nanoscale coordination polymers. We also illustrate how scaling down these materials to the nano-regime has enabled their use in a broad range of applications including catalysis, spin-crossover, templating, biosensing, biomedical imaging, and anticancer drug delivery. These results underscore the exciting opportunities of developing next-generation functional nanomaterials based on molecular components. PMID:19065692

  5. Detecting nanoscale vibrations as signature of life

    PubMed Central

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

    2015-01-01

    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. 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

  7. Calcium binding-mediated sustained release of minocycline from hydrophilic multilayer coatings targeting infection and inflammation.

    PubMed

    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 Ca(2+) 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, Ca(2+) concentration, and Ca(2+) 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 Ca(2+) binding affinity, enabling its use in a variety of biomedical applications. PMID:24409292

  8. Proof of Concept Thin Films and Multilayers Toward Enhanced Field Gradients in SRF Cavities

    SciTech Connect

    Lukaszew, R A; Beringer, D; Roach, W M; Eremeev, G V; Valente-Feliciano, A-M; Reece, C E; Xi, X

    2013-09-01

    Due to the very shallow penetration depth of the RF fields, SRF properties are inherently a surface phenomenon involving a material thickness of less than 1 micron thus opening up the possibility of using thin film coatings to achieve a desired performance. The challenge has been to understand the dependence of the SRF properties on the detailed characteristics of real surfaces and then to employ appropriate techniques to tailor these surface properties for greatest benefit. Our aim is to achieve gradients >100 MV/m and no simple material is known to be capable of sustaining this performance. A theoretical framework has been proposed which could yield such behavior [1] and it requires creation of thin film layered structures. I will present our systematic studies on such proof-of-principle samples. Our overarching goal has been to build a basic understanding of key nano-scale film growth parameters for materials that show promise for SRF cavity multilayer coatings and to demonstrate the ability to elevate the barrier for vortex entry in such layered structures above the bulk value of Hc1 for type-II superconductors and thus to sustain higher accelerating fields.

  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. The Vroman effect: competitive protein exchange with dynamic multilayer protein aggregates.

    PubMed

    Hirsh, Stacey L; McKenzie, David R; Nosworthy, Neil J; Denman, John A; Sezerman, Osman U; Bilek, Marcela M M

    2013-03-01

    The surface immobilization of proteins is an emerging field with applications in a wide range of important areas: biomedical devices, disease diagnosis, biosensing, food processing, biofouling, and bioreactors. Proteins, in Nature, often work synergistically, as in the important enzyme mixture, cellulase. It is necessary to preserve these synergies when utilizing surface immobilized proteins. However, the competitive displacement of earlier adsorbed proteins by other proteins with stronger binding affinities (the "Vroman effect") results in undesired layer instabilities that are difficult to control. Although this nanoscale phenomenon has been extensively studied over the last 40 years, the process through which this competitive exchange occurs is not well understood. This paper uses atomic force microscopy, QCM-D, TOF-SIMS, and in-solution TOF-MS to show that this competitive exchange process can occur through the turning of multilayer protein aggregates. This dynamic process is consistent with earlier postulated "transient complex" models, in which the exchange occurs in three stages: an initial layer adsorbs, another protein layer then embeds itself into the initial layer, forming a "transient complex;" the complex "turns," exposing the first layer to solution; proteins from the first layer desorb resulting in a final adsorbed protein composition that is enriched in proteins from the second layer. PMID:23261559

  11. Folding in power-law viscous multi-layers.

    PubMed

    Schmalholz, Stefan M; Schmid, Daniel W

    2012-04-28

    We study high-amplitude folding in layered rocks with two-dimensional numerical simulations. We employ the finite-element method to model shortening of an incompressible multi-layer with power-law viscous rheology. The Lagrangian numerical mesh is deformed and re-meshed to accurately follow the layer interfaces. Three settings are considered: (i) pure shearing of a confined multi-layer, (ii) simple shearing of a multi-layer above a detachment, and (iii) slump folding owing to gravity sliding. In our pure shear simulations, finite-amplitude folds always develop despite confinement and thin weak interlayers. The fold shapes can be significantly irregular, resulting from initial geometrical heterogeneities that are perturbations of the layer interfaces and differences in layer thickness. The bulk normal viscosity of the multi-layer decreases significantly with progressive folding. This structural softening decreases the bulk normal viscosities by a factor of 2-20. For simple shear, the multi-layer does not develop asymmetric fold shapes significantly. Fold axial planes in the multi-layer are mostly curved and not parallel. For slump folding, fold shapes can be significantly asymmetric exhibiting strongly curved fold axial planes and overturned fold limbs. The rheology of the competent layers has a major impact on the fold shapes for gravity-driven multi-layer folding. PMID:22431758

  12. Nanoscale surface modification studied by reflection anisotropy spectroscopy 

    E-print Network

    Lane, Paul David

    2009-11-26

    The development and control of nanoscale properties is a major goal in science and technology; for the development of such technologies it is important that there are experimental techniques which allow the monitoring ...

  13. Nanoscale Interpenetrating Phase Composites for Industrial and Vehicle Applications

    SciTech Connect

    2009-03-01

    This factsheet describes a study that will explore the technical and economic feasibility of producing nanoscale IPC components of a usable size for actual testing/implementation in a real application.

  14. Democratization of Nanoscale Imaging and Sensing Tools Using Photonics

    PubMed Central

    2015-01-01

    Providing means for researchers and citizen scientists in the developing world to perform advanced measurements with nanoscale precision can help to accelerate the rate of discovery and invention as well as improve higher education and the training of the next generation of scientists and engineers worldwide. Here, we review some of the recent progress toward making optical nanoscale measurement tools more cost-effective, field-portable, and accessible to a significantly larger group of researchers and educators. We divide our review into two main sections: label-based nanoscale imaging and sensing tools, which primarily involve fluorescent approaches, and label-free nanoscale measurement tools, which include light scattering sensors, interferometric methods, photonic crystal sensors, and plasmonic sensors. For each of these areas, we have primarily focused on approaches that have either demonstrated operation outside of a traditional laboratory setting, including for example integration with mobile phones, or exhibited the potential for such operation in the near future. PMID:26068279

  15. 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 ...

  16. 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 ...

  17. Nano-scale scratching in chemical-mechanical polishing

    E-print Network

    Eusner, Thor

    2008-01-01

    During the chemical-mechanical polishing (CMP) process, a critical step in the manufacture of ultra-large-scale integrated (ULSI) semiconductor devices, undesirable nano-scale scratches are formed on the surfaces being ...

  18. 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 ...

  19. 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 ...

  20. 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) ...

  1. Nanoscale Light Focusing and Imaging with Nano-Optical Devices 

    E-print Network

    Meenashi Sundaram, Vijay

    2014-09-23

    Energy transport analysis of micro/nano optics as well as their optimization to achieve high-throughput deep nanoscale patterning and microscopy is the goal of this study. To understand the energy transport in nano-optical ...

  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. 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 ...

  4. Manufacturing of Superhydrophobic Surfaces with Nanoscale and Microscale Features

    SciTech Connect

    2009-06-01

    This factsheet describes a research project that will develop a technology that will enable nanoscale and microscale superhydrophobic (SHP) features to be imaged onto surfaces for the high-volume manufacturing of water-repellent components and coatings.

  5. 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

  6. Hetero-twin formation during growth of nano-scale Al-TiN composites - experimental and DFT studies

    SciTech Connect

    Bhattacharyya, Dhriti; Liu, Xiang - Yang; Hoagland, Richard G; Misra, Amit; Genc, A; Fraser, H L

    2009-01-01

    It is well known that high stacking fault energy metals such as Al do not form either growth twins or mechanical twins easily. Although mechanical twins in nanocrystalline Al have been observed under certain conditions, growth twins have never been observed. In this work, the authors report for the first time, through transmission electron microscopy (TEM), that Al layers, when deposited on TiN layers, tend to grow in a twin relationship to both the TiN layer and the underlying Al layer. The TiN layers assume the orientation of the Al layers below. Calculations using density functional theory (DFT) show that nitrogen termination in the {l_brace}111{r_brace} growth plane of the TiN layers favors the growth of twin oriented Al layers over these TiN layers. This finding provides a way to create a twin-modulated structure in Al with the inclusion of intermediate nm-scale layer of an ionic solid such as TiN. Al metal is resistant to twinning, as it has a high stacking fault energy (SFE) of > 150 mJ/m. Although twins have been observed in nano-scale grains of Al, and predicted by molecular dynamics (MD) simulations in conditions when the nanoscale grains are plastically deformed, no process or phenomenon has been reported yet in which the deposition of an intermediate layer of a different material phase causes the subsequent layer of Al to be deposited in the twin orientation. The authors show in this paper that it is possible to form Al layers in twin orientation to each other across polar TiN layers, if these are grown so that both the Al and TiN layers have a {l_brace}111{r_brace} surface as their growth front. Since the deposition of Al and TiN layers is used in the formation of diffusion barriers, and the mechanical properties of these nanoscale multilayers are also seen to be exceptional, it is important to investigate and understand their structure at the nanometer length scale, and thence to be able to control it. Moreover, these findings point out a method of introducing nano-scale twins in high SFE materials in general, and can potentially improve the properties of nano-layered materials.

  7. Multilayered Electrospun Scaffolds for Tendon Tissue Engineering

    PubMed Central

    Chainani, Abby; Hippensteel, Kirk J.; Kishan, Alysha; Garrigues, N. William; Ruch, David S.; Guilak, Farshid

    2013-01-01

    Full-thickness rotator cuff tears are one of the most common causes of shoulder pain in people over the age of 65. High retear rates and poor functional outcomes are common after surgical repair, and currently available extracellular matrix scaffold patches have limited abilities to enhance new tendon formation. In this regard, tissue-engineered scaffolds may provide a means to improve repair of rotator cuff tears. Electrospinning provides a versatile method for creating nanofibrous scaffolds with controlled architectures, but several challenges remain in its application to tissue engineering, such as cell infiltration through the full thickness of the scaffold as well as control of cell growth and differentiation. Previous studies have shown that ligament-derived extracellular matrix may enhance differentiation toward a tendon or ligament phenotype by human adipose stem cells (hASCs). In this study, we investigated the use of tendon-derived extracellular matrix (TDM)-coated electrospun multilayered scaffolds compared to fibronectin (FN) or phosphate-buffered saline (PBS) coating for use in rotator cuff tendon tissue engineering. Multilayered poly(?-caprolactone) scaffolds were prepared by sequentially collecting electrospun layers onto the surface of a grounded saline solution into a single scaffold. Scaffolds were then coated with TDM, FN, or PBS and seeded with hASCs. Scaffolds were maintained without exogenous growth factors for 28 days in culture and evaluated for protein content (by immunofluorescence and biochemical assay), markers of tendon differentiation, and tensile mechanical properties. The collagen content was greatest by day 28 in TDM-scaffolds. Gene expression of type I collagen, decorin, and tenascin C increased over time, with no effect of scaffold coating. Sulfated glycosaminoglycan and dsDNA contents increased over time in culture, but there was no effect of scaffold coating. The Young's modulus did not change over time, but yield strain increased with time in culture. Histology demonstrated cell infiltration through the full thickness of all scaffolds and immunofluorescence demonstrated greater expression of type I, but not type III collagen through the full thickness of the scaffold in TDM-scaffolds compared to other treatment groups. Together, these data suggest that nonaligned multilayered electrospun scaffolds permit tenogenic differentiation by hASCs and that TDM may promote some aspects of this differentiation. PMID:23808760

  8. Simple solutions of multilayered discs subjected to biaxial moment loading.

    SciTech Connect

    Hsueh, Chun-Hway; Kelly, J R

    2009-01-01

    The purpose of this study was to derive a simple closed-form solution for the stress distribution through the thickness of multilayered discs subjected to biaxial moment loading, such that it can be used readily to evaluate the biaxial strength of multilayered dental ceramics using biaxial flexure tests. Methods A simple analytical model was developed to derive the stress distribution through the thickness of multilayered discs subjected to biaxial moment loading. The accuracy of the solution was verified by comparing with previous rigorous analytical solutions and finite element results. The results obtained from Roark's formulas for bilayered discs were also included for comparison.

  9. Characterization of Multilayers for X-ray Optics

    NASA Astrophysics Data System (ADS)

    Everett, J.; Romaine, S.; Southwick, J.; Hussein, A.; Bruni, R.; Ivan, A.; Clark, A.; Gorenstein, P.

    1997-12-01

    We are engaged in a program to develop multilayer coatings for hard X-ray telescopes. Using a DC magnetron sputtering process, multilayer coatings have been fabricated and we have investigated film quality as a result of changes in Argon backpressure. Various single layer and multilayer coatings have been deposited and characterization of these films has been carried out using Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Auger Electron Spectroscopy (AES), Rutherford Backscattering Spectroscopy (RBS), and X-Ray Reflectivity (XRR). The trends observed in film quality as a function of Argon backpressure are discussed.

  10. Enhanced electrical properties from barium strontium titanate multilayer films

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; Sun, Mengle; Zhang, Chao; Li, Liben; Chen, Qingdong

    2013-09-01

    Both multilayered and homogeneous BST films with the same ratio of Ba to Sr are prepared by metal-organic deposition on (111) Pt/Ti/SiO2/Si substrates. X-ray diffraction reveals the microstructure of the samples. Compared with the homogeneous BST film, the multilayered BST film shows improved electrical properties with smaller leakage current, larger dielectric constant, higher tunability and better ferroelectrity. These results are associated with the multilayered structure and strain-related interactions between layers, and the possible causes of which are discussed.

  11. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Speith, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials were evaluated for their rates of heat release and smoke generation. Top layers with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/cm2. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers

  12. Multilayer bandpass filter with extended lower and upper stop bands.

    PubMed

    Belyaev, B A; Tyurnev, V V

    2015-09-15

    We propose a novel design for a multilayer bandpass filter in which every resonant dielectric layer is separated from adjacent dielectric layers or from the ambient by a nonresonant grating of strip conductors on the layer interface. Here, every grating acts as a mirror with specified transparency. Relative to the conventional multilayer bandpass filter with multilayer dielectric mirrors, the proposed filter has multiply extended stop bands below and above the passband. Additionally, we provide formulas for computing the filter's frequency response. A comparison between the computed frequency responses for the proposed and conventional filters with the same passband is presented. PMID:26371929

  13. Investigation of structure and properties of novel multi-layer clay nanocomposite films produced controllably by continuous chaotic advection blending

    NASA Astrophysics Data System (ADS)

    Mahesha, Chaitra

    A unique processing technique based on chaotic advection developed at Clemson University and shown to controllably produce structured materials in the past was employed to produce structured nanocomposites with a high degree of clay orientation as well as localization of platelets within layers of nanoscale thicknesses. Continuous lengths of nanocomposites with different clay contents were extruded in the form of films by feeding separately melts of virgin polyamide-6 polymer and polyamide 6-clay masterbatch into a continuous chaotic advection blender. A variety of composite structures were producible at fixed clay compositions. The internal structure was characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Nanocomposites with novel in-situ multi-layered structures and a high degree of platelet orientation were formed by the recursive stretching and folding of the melt domains due to chaotic advection. Clay platelets were localized within discrete regions to form alternating virgin and platelet-rich layers leading to a hierarchical structure with multiple nano-scales. The thicknesses of the layers reduced with prolonged chaotic advection, eventually leading to nanocomposites in which the multi-layering was no longer discernible. The oriented platelets appeared to be homogenously dispersed through the bulk of the nanocomposite. Investigation of the morphology of the matrix by XRD showed that the homogeneity of the crystalline phase and the orientation of polymer chains parallel to the film surface increased with increased chaotic advection. Also, as the layer thickness reduced, the number of polymer chains restricted by clay platelets increased causing the gamma-crystalline fraction to increase. While XRD results suggested a change in total crystallinity with chaotic advection and clay content but without a specific trend, no change in crystallinity was measured by DSC. Such contradictions are consistent with results of other investigators. Concentrating and orienting the clay platelets within layers increases the path length of the diffusing molecule and hence may improve barrier properties. The effect of multi-layering and platelet orientation on the gas permeability of the nanocomposite films was investigated both experimentally and theoretically. Experimental measurements of 2% clay films showed that a multi-layered structure with oriented clay platelets gives a 40% greater reduction in oxygen permeability compared to a structure with a homogenous dispersion of oriented clay platelets. Also, the nanocomposite films with homogenous dispersion of platelets produced by chaotic advection due to their high degree of platelet alignment exhibited improved barrier properties than nanocomposites produced by mixing. The combination of high degree of orientation and multi-layering conferred to the 2 wt% clay film produced with the chaotic advection blender a relative permeability lower than a 6 wt% clay film produced with a single screw extruder. A theoretical model was formulated to explore the barrier properties of nanocomposites comprising a wide range of clay contents and platelet aspect ratio. The model showed the importance of orientation and layered structure. Permeabilities close to the intrinsic platelet permeability (i.e., near zero) can be realized by localizing and orienting a relatively low volume fraction (4%) of very high aspect ratio platelets (?350) in the matrix or high volume fractions (20%) of platelets with aspect ratios around 100 (typical of the montmorillonite (MMT) clay). The chaotic advection blender was unable, however, to process such masterbatches due to limitations of available screw extruders intended for polyolefins. Experiments considered low volume fractions of MMT clay less than 4%. Other physical properties of the films important for packaging applications were also evaluated. The presence of die lines, particulate contaminations and variations in thicknesses of the films led to data scatter of measured properties. Howe

  14. 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

  15. Highly Swollen Porous Microstructures in Polyelectrolyte Multilayers

    NASA Astrophysics Data System (ADS)

    Cho, Chungyeon; Kaiser, Jeremy; Zacharia, Nicole

    2011-03-01

    We investigated the creation of porous morphologies from polyelectrolyte multilayers (PEMs) consisting of linear poly(ethylenimine) and poly(acrylic acid), and poly (allylamine hydrochloride) and poly (acrylic acid) as a function of pH and immersion time under post-base assembly treatment. The porous transition is linked to the neutralization of the polycations electrolytes as well as ionization of PAA by the exposing LbL films to high pH. This causes PEMs to undergo spinodal decomposition, creating pores and an increase in film thickness. By using reactive wet stamping technique, we were able to locally cause porosity changes under high pH conditions in the LbL films. Further investigation of the mechanical properties of patterned LbL films was done by performing nano-indentation analysis. The results showed clear difference of physical properties such as hardness and modulus between stamped and unstamped regions based on porous transition.

  16. Multilayer steel composites -- Application and manufacturing

    SciTech Connect

    Vydra, E.J.

    1995-09-01

    At a time when both plastics and polymer-based composites have been making strides in the steel markets, materials utilizing steel and its strong features, along with additional required properties, have become more and more popular. These materials are multilayer composite structures consisting of layers of metal bonded or separated by adhesives, polymeric films, ceramic layers, etc. Existing and potential applications of such materials, including noise and vibration reduction, weight reduction and corrosion protection are described. Material properties are presented together with families of materials for different applications. Also presented are recommendations on parts` manufacturing techniques, including deep drawing, press forming, welding, etc. Development of these materials was accompanied by new approaches in manufacturing that will also be discussed.

  17. Multilayer hexagonal silicon forming in slit nanopore.

    PubMed

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-01-01

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties. PMID:26435518

  18. Multilayer insulation blanket, fabricating apparatus and method

    DOEpatents

    Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

    1992-09-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel. 7 figs.

  19. Method of fabricating a multilayer insulation blanket

    DOEpatents

    Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

    1993-07-06

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  20. Multilayer insulation blanket, fabricating apparatus and method

    DOEpatents

    Gonczy, John D. (Oak Lawn, IL); Niemann, Ralph C. (Downers Grove, IL); Boroski, William N. (Aurora, IL)

    1992-01-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  1. Method of fabricating a multilayer insulation blanket

    DOEpatents

    Gonczy, John D. (Oak Lawn, IL); Niemann, Ralph C. (Downers Grove, IL); Boroski, William N. (Aurora, IL)

    1993-01-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  2. Multilayer Bicontinuous DMRT Model for Terrestrial Snowpack

    NASA Astrophysics Data System (ADS)

    Xu, X.; Tan, S.; Tsang, L.; Yueh, S. H.; Lemmetyinen, J.

    2013-12-01

    Recently the bicontinuous model has drawn a lot of attention due to its ability of representing the complex structure of the snow samples. In the previous paper, we discussed the generation of the bicontinuous microstructure for snow sample, the statistical characterization of the bicontinuous media and the electromagnetic scattering properties. This flexibility of the snow sample generation and corresponding distinct scattering properties made the bicontinuous model easier to handle a variety of snow types, from fresh snow to depth hoar. The backscattering of one layer of snow was calculated by combining the bicontinuous model into the dense media radiative transfer (DMRT) theory. The purpose of this paper is to illustrate the connection between the input parameters for bicontinuous configuration and snow pit measurements in detail and incorporate layering effect by extending the signal layer Bicontinuous/DMRT into multi-layer model. The digitized random morphology is generated by superimposing a large number of stochastic waves. The corresponding random function is determined by the cutting level, the shape and scale parameters of the distribution function. By using those three parameters, the equations have been derived to calculate the snow density, auto correlation function, specific surface area of the snow and effective snow grain sizes. That means we can set up the bicontinuous model according to the snow pit measurements. Then, we check the scattering coefficients of the bicontinuous sample verses different snow densities and grain sizes, which is in agree with the experiments. Moderate forward scattering has been found in the new model by calculating the mean cosine. Next, we couple the bicontinuous model with the multi-layer DMRT. In general, snow from different storms will go through different metamorphism and form layered structure. Therefore, we take into account the layering effect by formulating the multi-layer DMRT. The bistatic scattering properties of the differential snow volume are calculated from bicontinuous model for each layer. To solve the dense media radiative transfer equation for layered snow, the specific intensity in the equation is decomposed into a sum of the reduced intensity and diffuse intensity. The reduced intensities in every layer can be solved analytically. We decompose the diffuse intensities into Fourier series in the azimuthal direction, and then using the Eigen-quadrature approach to solve the coefficient of every harmonic. We consider full multiple scattering effects with 16 Gaussian quadrature angles. As for the ground surface under the snow, the rough surface effect is considered through a look up table. The look up table is generated by solving full wave simulations of Numerical Maxwell Model in 3 Dimensional (NMM3D) rough surfaces. The Bicontinuous/DMRT multi-layer model has been validated by the data acquired at Colorado with 13.4GHz POLSCAT data and at Finland with the dual frequency (9.6GHz &17.2 GHz) SNOWSAR data.

  3. Multi-Layered Cancer Chromosomal Instability Phenotype

    PubMed Central

    Roschke, Anna V.; Rozenblum, Ester

    2013-01-01

    Whole-chromosomal instability (W-CIN) – unequal chromosome distribution during cell division – is a characteristic feature of a majority of cancer cells distinguishing them from their normal counterparts. The precise molecular mechanisms that may cause mis-segregation of chromosomes in tumor cells just recently became more evident. The consequences of W-CIN are numerous and play a critical role in carcinogenesis. W-CIN mediates evolution of cancer cell population under selective pressure and can facilitate the accumulation of genetic changes that promote malignancy. It has both tumor-promoting and tumor-suppressive effects, and their balance could be beneficial or detrimental for carcinogenesis. The characterization of W-CIN as a complex multi-layered adaptive phenotype highlights the intra- and extracellular adaptations to the consequences of genome reshuffling. It also provides a framework for targeting aggressive chromosomally unstable cancers. PMID:24377086

  4. High numerical aperture multilayer Laue lenses

    PubMed Central

    Morgan, Andrew J.; Prasciolu, Mauro; Andrejczuk, Andrzej; Krzywinski, Jacek; Meents, Alke; Pennicard, David; Graafsma, Heinz; Barty, Anton; Bean, Richard J.; Barthelmess, Miriam; Oberthuer, Dominik; Yefanov, Oleksandr; Aquila, Andrew; Chapman, Henry N.; Bajt, Saša

    2015-01-01

    The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilise their capability for imaging and probing biological cells, nanodevices, and functional matter on the nanometer scale with chemical sensitivity. Here we demonstrate focusing a hard X-ray beam to an 8?nm focus using a volume zone plate (also referred to as a wedged multilayer Laue lens). This lens was constructed using a new deposition technique that enabled the independent control of the angle and thickness of diffracting layers to microradian and nanometer precision, respectively. This ensured that the Bragg condition is satisfied at each point along the lens, leading to a high numerical aperture that is limited only by its extent. We developed a phase-shifting interferometric method based on ptychography to characterise the lens focus. The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1?nm resolution. PMID:26030003

  5. Multilayer hexagonal silicon forming in slit nanopore

    NASA Astrophysics Data System (ADS)

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-10-01

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties.

  6. High numerical aperture multilayer Laue lenses

    DOE PAGESBeta

    Morgan, Andrew J.; Prasciolu, Mauro; Andrejczuk, Andrzej; Krzywinski, Jacek; Meents, Alke; Pennicard, David; Graafsma, Heinz; Barty, Anton; Bean, Richard J.; Barthelmess, Miriam; et al

    2015-06-01

    The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilise their capability for imaging and probing biological cells, nanodevices, and functional matter on the nanometer scale with chemical sensitivity. Here we demonstrate focusing a hard X-ray beam to an 8 nm focus using a volume zone plate (also referred to as a wedged multilayer Laue lens). This lens was constructed using a new deposition technique that enabled the independent control of the angle and thickness of diffracting layers to microradian and nanometer precision, respectively. This ensured that the Bragg condition is satisfied at each point along themore »lens, leading to a high numerical aperture that is limited only by its extent. We developed a phase-shifting interferometric method based on ptychography to characterise the lens focus. The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1 nm resolution.« less

  7. Fast multilayer fission chamber with 239Pu

    NASA Astrophysics Data System (ADS)

    Bogdzel, A. A.; Gundorin, N. A.; Duka-Zolyòmi, À.; Kliman, J.; Grigoriev, Yu. V.

    1994-04-01

    For the investigation of neutron induced fission of heavy nuclei in the resonance energy range the fast multilayer ionization fission chamber with a 239Pu content of 1.6 g was constructed. The chamber is compact and a minimum of material has been used for its construction. The chamber is divided into 19 sections containing no more than 100 mg of 239Pu in a section whose intrinsic capacity is less than 100 pF. By using fast preamplifiers and constant fraction discriminators together with the combined method of amplitude and pulse length discrimination the background due to ?-particles is suppressed and a less perturbed pulse height distribution is obtained. The absolute fission fragments detection efficiency of the chamber is (60±8)%. Its time resolution does not exceed 2.6 ns.

  8. Multilayer optical disc system using homodyne detection

    NASA Astrophysics Data System (ADS)

    Kurokawa, Takahiro; Ide, Tatsuro; Tanaka, Yukinobu; Watanabe, Koichi

    2014-09-01

    A write/read system using high-productivity multilayer optical discs was developed. The recording medium used in the system consists of planar recording layers and a separated guide layer, and is fabricated by web coating and lamination process. The recording layers in the medium are made of one-photon-absorption material, on which data can be recorded with a normal laser diode. The developed system is capable of focusing and tracking on the medium and amplifying readout signals by using phase-diversity homodyne detection. A highly layer-selective focusing method using homodyne detection was also proposed. This method obtains stable focus-error signals with clearly separated S-shaped curves even when layer spacing is quite narrow, causing large interlayer crosstalk. Writing on the medium and reading with the signal amplification effect of homodyne detection was demonstrated. In addition, the effectiveness of the method was experimentally evaluated.

  9. A multilayer surface detector for ultracold neutrons

    NASA Astrophysics Data System (ADS)

    Wang, Zhehui; Hoffbauer, M. A.; Morris, C. L.; Callahan, N. B.; Adamek, E. R.; Bacon, J. D.; Blatnik, M.; Brandt, A. E.; Broussard, L. J.; Clayton, S. M.; Cude-Woods, C.; Currie, S.; Dees, E. B.; Ding, X.; Gao, J.; Gray, F. E.; Hickerson, K. P.; Holley, A. T.; Ito, T. M.; Liu, C.-Y.; Makela, M.; Ramsey, J. C.; Pattie, R. W.; Salvat, D. J.; Saunders, A.; Schmidt, D. W.; Schulze, R. K.; Seestrom, S. J.; Sharapov, E. I.; Sprow, A.; Tang, Z.; Wei, W.; Wexler, J.; Womack, T. L.; Young, A. R.; Zeck, B. A.

    2015-10-01

    A multilayer surface detector for ultracold neutrons (UCNs) is described. The top 10B layer is exposed to vacuum and directly captures UCNs. The ZnS:Ag layer beneath the 10B layer is a few microns thick, which is sufficient to detect the charged particles from the 10B(n,?)7Li neutron-capture reaction, while thin enough that ample light due to ? and 7Li escapes for detection by photomultiplier tubes. A 100-nm thick 10B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials, and other parameters. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparison with other existing 3He and 10B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.

  10. Plasmon Resonance in Multilayer Graphene Nanoribbons

    E-print Network

    Emani, Naresh Kumar; Chung, Ting-Fung; Prokopeva, Ludmila J; Kildishev, Alexander V; Shalaev, Vladimir M; Chen, Yong P; Boltasseva, Alexandra

    2015-01-01

    Plasmon resonance in nanopatterned single layer graphene nanoribbon (SL-GNR), double layer graphene nanoribbon (DL-GNR) and triple layer graphene nanoribbon (TL-GNR) structures is studied both experimentally and by numerical simulations. We use 'realistic' graphene samples in our experiments to identify the key bottle necks in both experiments and theoretical models. The existence of electrical tunable plasmons in such stacked multilayer GNRs was first experimentally verified by infrared microscopy. We find that the strength of the plasmonic resonance increases in DL-GNR when compared to SL-GNRs. However, we do not find a further such increase in TL-GNRs compared to DL-GNRs. We carried out systematic full wave simulations using finite element technique to validate and fit experimental results, and extract the carrier scattering rate as a fitting parameter. The numerical simulations show remarkable agreement with experiments for unpatterned SLG sheet, and a qualitative agreement for patterned graphene sheet. W...

  11. Investigation of multilayer magnetic domain lattice file

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A theoretical and experimental investigation determined that current accessed self structured bubble memory devices have the potential of meeting projected data density and speed requirements. Device concepts analyzed include multilayer ferrimagnetic devices where the top layer contains a domain structure which defines the data location and the second contains the data. Current aperture and permalloy assisted current propagation devices were evaluated. Based on the result of this work more detailed device research was initiated. Detailed theoretical and experimental studies indicate that the difference in strip and threshold between a single bubble in the control layer and a double bubble which would exist in both the control layer and data layer is adequate to allow for detection of data. Detailed detector designs were investigated.

  12. Multilayer hexagonal silicon forming in slit nanopore

    PubMed Central

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-01-01

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties. PMID:26435518

  13. High numerical aperture multilayer Laue lenses

    SciTech Connect

    Morgan, Andrew J.; Prasciolu, Mauro; Andrejczuk, Andrzej; Krzywinski, Jacek; Meents, Alke; Pennicard, David; Graafsma, Heinz; Barty, Anton; Bean, Richard J.; Barthelmess, Miriam; Oberthuer, Dominik; Yefanov, Oleksandr; Aquila, Andrew; Chapman, Henry N.; Bajt, Saša

    2015-06-01

    The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilise their capability for imaging and probing biological cells, nanodevices, and functional matter on the nanometer scale with chemical sensitivity. Here we demonstrate focusing a hard X-ray beam to an 8 nm focus using a volume zone plate (also referred to as a wedged multilayer Laue lens). This lens was constructed using a new deposition technique that enabled the independent control of the angle and thickness of diffracting layers to microradian and nanometer precision, respectively. This ensured that the Bragg condition is satisfied at each point along the lens, leading to a high numerical aperture that is limited only by its extent. We developed a phase-shifting interferometric method based on ptychography to characterise the lens focus. The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1 nm resolution.

  14. Transmission fingerprints in quasiperiodic dielectric multilayers

    NASA Astrophysics Data System (ADS)

    Vasconcelos, M. S.; Albuquerque, E. L.

    1999-05-01

    We investigate the optical transmission fingerprints in structures that exhibit deterministic disorders. A class of models that has attracted particular attention in this context are the quasiperiodic dielectric multilayers that obey a substitutional sequence. These substitutional sequence are characterized by the nature of their Fourier spectrum, which can be dense pure point (Fibonacci sequences), singular continuous (Thue-Morse and double-period sequences), and absolutely continuous (Rudin-Shapiro sequence). We use a transfer-matrix approach to derive the optical transmission coefficients. Numerical results are presented to illustrate the self-similar aspect of the spectra, as well as to show the optical fingerprint through a return map of the transmission coefficients.

  15. Wrapped multilayer insulation design and testing

    NASA Astrophysics Data System (ADS)

    Dye, S. A.; Tyler, P. N.; Mills, G. L.; Kopelove, A. B.

    2014-11-01

    New vehicles need improved cryogenic propellant storage and transfer capabilities for long duration missions. Multilayer insulation (MLI) for cryogenic propellant feedlines is much less effective than MLI tank insulation, with heat leak into spiral wrapped MLI on pipes 3-10 times higher than conventional tank MLI. Better insulation for cryogenic feed lines is an important enabling technology that could help NASA reach cryogenic propellant storage and transfer requirements. Improved insulation for Ground Support Equipment could reduce cryogen losses during launch vehicle loading. Wrapped-MLI (WMLI) is a high performance multilayer insulation using innovative discrete spacer technology specifically designed for cryogenic transfer lines and Vacuum Jacketed Pipe (VJP) to reduce heat flux. The poor performance of traditional MLI wrapped on feed lines is due in part to compression of the MLI layers, with increased interlayer contact and heat conduction. WMLI uses discrete spacers that maintain precise layer spacing, with a unique design to reduce heat leak. A Triple Orthogonal Disk spacer was engineered to minimize contact area/length ratio and reduce solid heat conduction for use in concentric MLI configurations. A new insulation, WMLI, was developed and tested. Novel polymer spacers were designed, analyzed and fabricated; different installation techniques were examined; and rapid prototype nested shell components to speed installation on real world piping were designed and tested. Prototypes were installed on tubing set test fixtures and heat flux measured via calorimetry. WMLI offered superior performance to traditional MLI installed on cryogenic pipe, with 2.2 W/m2 heat flux compared to 26.6 W/m2 for traditional spiral wrapped MLI (5 layers, 77-295 K). WMLI as inner insulation in VJP can offer heat leaks as low as 0.09 W/m, compared to industry standard products with 0.31 W/m. WMLI could enable improved spacecraft cryogenic feedlines and industrial hot/cold transfer lines.

  16. 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.

  17. A reservoir management strategy for multilayered reservoirs in eastern Venezuela 

    E-print Network

    Espinel Diaz, Arnaldo Leopoldo

    1998-01-01

    A reservoir management strategy has been developed for a field located in eastern Venezuela. The field contains deep, high pressure, multilayer reservoirs. A thorough formation evaluation was accomplished using the log data, core data, PVT data...

  18. Tunable drug loading and release from polypeptide multilayer nanofilms

    PubMed Central

    Jiang, Bingbing; Li, Bingyun

    2009-01-01

    Polypeptide multilayer nanofilms were prepared using electrostatic layer-by-layer self-assembly nanotechnology. Small charged drug molecules (eg, cefazolin, gentamicin, and methylene blue) were loaded in polypeptide multilayer nanofilms. Their loading and release were found to be pH-dependent and could also be controlled by changing the number of film layers and drug incubation time, and applying heat-treatment after film formation. Antibioticloaded polypeptide multilayer nanofilms showed controllable antibacterial properties against Staphylococcus aureus. The developed biodegradable polypeptide multilayer nanofilms are capable of loading both positively- and negatively-charged drug molecules and promise to serve as drug delivery systems on biomedical devices for preventing biomedical device-associated infection, which is a significant clinical complication for both civilian and military patients. PMID:19421369

  19. Strategies for incorporating functional block copolymers into polyelectrolyte multilayer coatings

    E-print Network

    Tan, Wui Siew

    2011-01-01

    This thesis explores the creation of thin film responsive hydrogel coatings via Layer-by Layer assembly (LbL) of temperature (T) responsive block copolymer - polyelectrolyte multilayers (PEMs). First, the LbL conditions ...

  20. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Spieth, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire-blocking layer, and cushion-reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat-release rate of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicon adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis.

  1. Hollow multilayer photonic bandgap fibers for NIR applications

    E-print Network

    Bayindir, Mehmet

    -scalable hollow optical fibres with large photonic bandgaps for CO2 laser transmission," Nature 420, 650-653 (2002 codes: (060.2280) Fiber design and fabrication, (230.4170) Multilayers, (160.4670) Optical materials

  2. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

    Shirahata, Yasuhiro; Wada, Eiji; Itoh, Mitsuru; Taniyama, Tomoyasu

    2014-01-20

    Spin filtering at perpendicular magnetized Cu/Ni multilayer/GaAs(001) interfaces is demonstrated at remanence using optical spin orientation method. [Cu(9?nm)/Ni(t{sub Ni} nm)]{sub n} multilayers are found to show a crossover from the in-plane to out-of-plane magnetic anisotropy at the Cu/Ni bilayer repetition n?=?4 and the Ni layer thickness t{sub Ni}?=?3. For a perpendicularly magnetized Cu/Ni multilayer/n-GaAs(001) interface, circular polarization dependent photocurrent shows a clear hysteretic behavior under optical spin orientation conditions as a function of magnetic field out-of-plane while the bias dependence exhibits a substantial peak at a forward bias, verifying that Cu/Ni multilayers work as an efficient spin filter in the remanent state.

  3. Optimization of broadband optical response of multilayer nanospheres

    E-print Network

    Qiu, Wenjun

    We propose an optimization-based theoretical approach to tailor the optical response of silver/silica multilayer nanospheres over the visible spectrum. We show that the structure that provides the largest cross-section per ...

  4. Enhanced Radiation Tolerance in Sputtered Cu/V Multilayers 

    E-print Network

    Fu, Engang

    2010-10-12

    of the GMR effect, scientists and engineers keep on making impressive progress in increasing the data storage capacity. These research efforts also lead to a new exciting research area, named ?spintronics? where metallic multilayers play a critical role...

  5. EUV-multilayers on grating-like topographies

    SciTech Connect

    van Boogaard, A. J. R.; Louis, E.; Goldberg, K. A.; Mochi, I.; Bijkerk, F.

    2010-03-12

    In this study, multilayer morphology near the key anomalies in grating-like structures, namely sharp step-edges and steep walls, are examined. Different deposition schemes are employed. Based on cross section TEM analysis an explanatory model describing the morphology of the successive layers is developed. A further insight into the periodicity and the general performance of the multilayer is obtained by EUV microscopy. The main distortions in multilayer structure and hence EUV performance are found to be restricted to a region within a few hundred nanometers from the anomalies, which is very small compared to the proposed grating period (50-100 {micro}m). These multilayer coated blazed gratings can thus be considered a viable option for spectral purity enhancement of EUV light sources.

  6. The Use of Genetic Algorithms in Multilayer Mirror Optimization

    E-print Network

    Hart, Gus

    The Use of Genetic Algorithms in Multilayer Mirror Optimization by Shannon Lunt March 1999 of the Chromosomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6 Flow chart of the Genetic Algorithm.7 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2 Genetic

  7. Polyelectrolyte multilayers for tunable release of antibiotics and other therapeutics

    E-print Network

    Chuang, Helen F

    2008-01-01

    Polyelectrolyte multilayers (PEMs) were fabricated via the layer-by-layer (LbL) deposition process, incorporating hydrolytically degradable poly([beta]-amino esters) to result in biodegradable PEMs that can release active ...

  8. Ballistic resistance of multi-layered steel shields

    E-print Network

    Huang, Min, S.M. Massachusetts Institute of Technology

    2007-01-01

    In this thesis, the ballistic resistance of multi-layered steel shields against projectile impact at the sub-ordnance velocity is evaluated using finite element simulations. Eight types of projectiles of different weight ...

  9. Developing Multilayer Thin Film Strain Sensors With High Thermal Stability

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

    2006-01-01

    A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

  10. Field induced switching in multilayer rhombic magnetic rings

    E-print Network

    Pacella, James N

    2007-01-01

    Multilayer rhombic magnetic rings are researched as a structure for the "pseudo spin valve" device that could possibly become useful in magnetic materials applications such as MRAM, digital logic, and sensors through the ...

  11. Computer-aided design for multilayer microfluidic chips

    E-print Network

    Amin, Nada

    2009-01-01

    Microfluidic chips fabricated by multilayer soft lithography are emerging as "lab-on-a-chip" systems that can automate biological experiments. As we are able to build more complex microfluidic chips with thousands of ...

  12. New focusing multilayer structures for X-ray plasma spectroscopy

    SciTech Connect

    Bibishkin, M S; Luchin, V I; Salashchenko, N N; Chernov, V V; Chkhalo, N I; Kazakov, E D; Shevelko, A P

    2008-02-28

    New focusing short-period multilayer structures are developed which opens up wide possibilities for X-ray and VUV spectroscopy. Multilayer structures are deposited on a flat surface of a mica crystal which is then bent to a small-radius cylinder. The use of this structure in a von Hamos spectrometer for X-ray laser plasma diagnostics is demonstrated. (interaction of laser radiation with matter. laser plasma)

  13. Anomalous magnetic moments in Co/Nb multilayers

    NASA Astrophysics Data System (ADS)

    Chuang, T. M.; Lee, S. F.; Huang, S. Y.; Yao, Y. D.; Cheng, W. C.; Huang, G. R.

    2002-02-01

    Response of Co/Nb multilayers to external field near the superconducting transition temperature ( TC) was studied. The average moment of Co was suppressed with decreasing Co thickness. At 10 K, for Co thickness larger than 0.5 nm, the multilayers showed hysteresis and ferromagnetism. Some samples showed anomalous field-cooled paramagnetic moments, similar to Paramagnetic Meissner Effect (PME). This is attributed not to the Co moment but to the suppressed surface TC causing PME.

  14. Multilayer erosion resistant coatings for the protection of aerospace components

    NASA Astrophysics Data System (ADS)

    Borawski, Brian

    Application of a monolithic layer of titanium nitride (TiN) has been found to increase the erosion resistance of engine compressor components such as turbine blades. However, there is very limited public domain research on the erosion resistance conveyed by multilayer hard coatings. In addition, data from multilayer coating studies may present seemingly contradictory results due to the wide variation in coating systems and coating architectures investigated. This thesis presents a systematic study of multilayer coatings based on TiN/Ti and TiN/X, where X = Zr, Hf, or Nb, in order to determine the effect of multilayer coating design and interlayer materials on the hard particle erosion resistance of these coating systems. Multilayer coatings were eroded using glass beads, quartz and alumina media, with particle velocities ranging from 75 to 180 m/s. Erosion performance was found to depend strongly on the TiN/Ti coating multilayer design architecture and the erosion conditions. Coatings with two layers, one of TiN, the other a thin titanium bond layer, gave optimal erosion performance against the alumina erodent, whereas coatings with 32 layers (16 each of TiN and Ti) with a high volume fraction of titanium, offered the best erosion performance against the glass bead erodent. TiN-based coatings with interlayers of Ti, Zr, Hf, and Nb were compared to determine the effect of interlayer material on erosion performance. High values of Vickers microhardness were found to correlate with poor erosion performance. The TiN/Zr multilayer coatings exhibited the worst durability for all erosion conditions, followed by TiN/Hf. The TiN/Nb multilayer coatings provided the best durability for quartz and glass bead erodents. Although TiN/Ti coatings showed better durability than TiN/Nb against alumina particles, this discrepancy was attributed to the thinner than anticipated total thickness of the TiN/Nb coatings.

  15. Superconducting multilayer structures grown by ALL-MBE

    SciTech Connect

    Bozovic, I.; Eckstein, J.N.; Klausmeier-Brown, M.E.; Virshup, G.F.; Ralls, K.S.

    1992-05-21

    Thin films of various Bi-Sr-Ca-Cu-O (2201, 2212, {hor_ellipsis}, 2-2-11-12) compounds have been synthesized using atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). Signal-crystal films with excellent transport properties, smooth surfaces and atomically sharp interfaces in multilayer structures have been obtained. That made it possible to deposit virtually perfect ultrathin layers and superlattices, and fabricate hysteretic Josephson junctions from SIS multilayers. 6 refs.

  16. Superconducting multilayer structures grown by ALL-MBE

    SciTech Connect

    Bozovic, I.; Eckstein, J.N.; Klausmeier-Brown, M.E.; Virshup, G.F. . Varian Research Center); Ralls, K.S. )

    1992-05-21

    Thin films of various Bi-Sr-Ca-Cu-O (2201, 2212, {hor ellipsis}, 2-2-11-12) compounds have been synthesized using atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). Signal-crystal films with excellent transport properties, smooth surfaces and atomically sharp interfaces in multilayer structures have been obtained. That made it possible to deposit virtually perfect ultrathin layers and superlattices, and fabricate hysteretic Josephson junctions from SIS multilayers. 6 refs.

  17. Nanoscale optical tomography with cathodoluminescence spectroscopy.

    PubMed

    Atre, Ashwin C; Brenny, Benjamin J M; Coenen, Toon; García-Etxarri, Aitzol; Polman, Albert; Dionne, Jennifer A

    2015-05-01

    Tomography has enabled the characterization of the Earth's interior, visualization of the inner workings of the human brain, and three-dimensional reconstruction of matter at the atomic scale. However, tomographic techniques that rely on optical excitation or detection are generally limited in their resolution by diffraction. Here, we introduce a tomographic technique--cathodoluminescence spectroscopic tomography--to probe optical properties in three dimensions with nanometre-scale spatial and spectral resolution. We first obtain two-dimensional cathodoluminescence maps of a three-dimensional nanostructure at various orientations. We then use the method of filtered back-projection to reconstruct the cathodoluminescence intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can be further correlated with the radiative local density of optical states in particular regions of the reconstruction. We demonstrate how cathodoluminescence tomography can be used to achieve nanoscale three-dimensional visualization of light-matter interactions by reconstructing a three-dimensional metal-dielectric nanoresonator. PMID:25849788

  18. Nonlocal normal modes in nanoscale dynamical systems

    NASA Astrophysics Data System (ADS)

    Adhikari, S.; Gilchrist, D.; Murmu, T.; McCarthy, M. A.

    2015-08-01

    This paper introduces the idea of nonlocal normal modes arising in the dynamic analysis of nanoscale structures. A nonlocal finite element approach is developed for the axial vibration of nanorods, bending vibration of nanobeams and transverse vibration of nanoplates. Explicit expressions of the element mass and stiffness matrices are derived in closed-form as functions of a length-scale parameter. In general the mass matrix can be expressed as a sum of the classical local mass matrix and a nonlocal part. The nonlocal part of the mass matrix is scale-dependent and vanishes for systems with larger lengths. Classical modal analysis and perturbation method are used to understand the dynamic behaviour of discrete nonlocal systems in the light of classical local systems. The conditions for the existence of classical normal modes for undamped and damped nonlocal systems are established. Closed-form approximate expressions of nonlocal natural frequencies, modes and frequency response functions are derived. Results derived in the paper are illustrated using examples of axial and bending vibration of nanotubes and transverse vibration of graphene sheets.

  19. 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. This work was supported by the US NSF Grant No. DMR-0844899, the Swiss NSF, the NCCR MaNEP and QSIT, the European STREP project Nanopower, the CSIC and FSE JAE-Doc program, the Spanish MAT2011-24331 and the ITN Grant 234970 (EU)

  20. 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.

  1. 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.

  2. Design of a nanoscale silicon laser

    NASA Astrophysics Data System (ADS)

    Jaiswal, S. L.; Simpson, J. T.; Withrow, S. P.; White, C. W.; Norris, P. M.

    The recent observation of optical gain from silicon nanocrystals embedded in SiO2 opens an opportunity to develop a nanoscale silicon-based laser. However, the challenge remains to design and develop a laser architecture using CMOS-compatible materials. In this paper we present two designs for a waveguide laser in which silicon nanocrystals embedded in SiO2 are used as the optical gain media. One design employs a SiO2 membrane containing encapsulated Si nanocrystals. Preliminary calculations given here show that a highly resonant laser cavity can be produced in a SiO2 membrane using sub-wavelength structures. This photonic crystal architecture, used to guide and contain the light, can be combined with a gain medium of optically active Si nanocrystals synthesized in the SiO2 membrane using ion implantation/thermal annealing to produce a Si-based laser. The laser cavity dimensions can be matched to the near-infrared wavelengths where optical gain has been observed from Si nanocrystals. The second design utilizes silicon nanocrystals embedded in a distributed-feedback laser cavity fabricated in SiO2. Lasing action over a broad wavelength range centered at 770 nm should be possible in both of these configurations.

  3. 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.

  4. Primary thermometry with nanoscale tunnel junctions

    SciTech Connect

    Hirvi, K.P.; Kauppinen, J.P.; Paalanen, M.A.; Pekola, J.P.

    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.

  5. Nanoscale platinum printing on insulating substrates

    NASA Astrophysics Data System (ADS)

    O'Connell, C. D.; Higgins, M. J.; Sullivan, R. P.; Jamali, S. S.; Moulton, S. E.; Wallace, G. G.

    2013-12-01

    The deposition of noble metals on soft and/or flexible substrates is vital for several emerging applications including flexible electronics and the fabrication of soft bionic implants. In this paper, we describe a new strategy for the deposition of platinum electrodes on a range of materials, including insulators and flexible polymers. The strategy is enabled by two principle advances: (1) the introduction of a novel, low temperature strategy for reducing chloroplatinic acid to platinum using nitrogen plasma; (2) the development of a chloroplatinic acid based liquid ink formulation, utilizing ethylene glycol as both ink carrier and reducing agent, for versatile printing at nanoscale resolution using dip-pen nanolithography (DPN). The ink formulation has been printed and reduced upon Si, glass, ITO, Ge, PDMS, and Parylene C. The plasma treatment effects reduction of the precursor patterns in situ without subjecting the substrate to destructively high temperatures. Feature size is controlled via dwell time and degree of ink loading, and platinum features with 60 nm dimensions could be routinely achieved on Si. Reduction of the ink to platinum was confirmed by energy dispersive x-ray spectroscopy (EDS) elemental analysis and x-ray diffraction (XRD) measurements. Feature morphology was characterized by optical microscopy, SEM and AFM. The high electrochemical activity of individually printed Pt features was characterized using scanning electrochemical microscopy (SECM).

  6. 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.

  7. Mechanical Computing Redux: Limitations at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Liu, Tsu-Jae King

    2014-03-01

    Technology solutions for overcoming the energy efficiency limits of nanoscale complementary metal oxide semiconductor (CMOS) technology ultimately will be needed in order to address the growing issue of integrated-circuit chip power density. Off-state leakage current sets a fundamental lower limit in energy per operation for any voltage-level-based digital logic implemented with transistors (CMOS and beyond), which leads to practical limits for device density (i.e. cost) and operating frequency (i.e. system performance). Mechanical switches have zero off-state leakag and hence can overcome this fundamental limit. Contact adhesive force sets a lower limit for the switching energy of a mechanical switch, however, and also directly impacts its performance. This paper will review recent progress toward the development of nano-electro-mechanical relay technology and discuss remaining challenges for realizing the promise of mechanical computing for ultra-low-power computing. Supported by the Center for Energy Efficient Electronics Science (NSF Award 0939514).

  8. New Dark Matter Detector using Nanoscale Explosives

    E-print Network

    Lopez, Alejandro; Freese, Katherine; Kurdak, Cagliyan; Tarle, Gregory

    2014-01-01

    We present nanoscale explosives as a novel type of dark matter detector and study the ignition properties. When a Weakly Interacting Massive Particle WIMP from the Galactic Halo elastically scatters off of a nucleus in the detector, the small amount of energy deposited can trigger an explosion. For specificity, this paper focuses on a type of two-component explosive known as a nanothermite, consisting of a metal and an oxide in close proximity. When the two components interact they undergo a rapid exothermic reaction --- an explosion. As a specific example, we consider metal nanoparticles of 5 nm radius embedded in an oxide. One cell contains more than a few million nanoparticles, and a large number of cells adds up to a total of 1 kg detector mass. A WIMP interacts with a metal nucleus of the nanoparticles, depositing enough energy to initiate a reaction at the interface between the two layers. When one nanoparticle explodes it initiates a chain reaction throughout the cell. A number of possible thermite mat...

  9. Nanoscale optical tomography with cathodoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Atre, Ashwin C.; Brenny, Benjamin J. M.; Coenen, Toon; García-Etxarri, Aitzol; Polman, Albert; Dionne, Jennifer A.

    2015-05-01

    Tomography has enabled the characterization of the Earth's interior, visualization of the inner workings of the human brain, and three-dimensional reconstruction of matter at the atomic scale. However, tomographic techniques that rely on optical excitation or detection are generally limited in their resolution by diffraction. Here, we introduce a tomographic technique—cathodoluminescence spectroscopic tomography—to probe optical properties in three dimensions with nanometre-scale spatial and spectral resolution. We first obtain two-dimensional cathodoluminescence maps of a three-dimensional nanostructure at various orientations. We then use the method of filtered back-projection to reconstruct the cathodoluminescence intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can be further correlated with the radiative local density of optical states in particular regions of the reconstruction. We demonstrate how cathodoluminescence tomography can be used to achieve nanoscale three-dimensional visualization of light-matter interactions by reconstructing a three-dimensional metal-dielectric nanoresonator.

  10. Emission properties of colloidal quantum dots on polyelectrolyte multilayers

    NASA Astrophysics Data System (ADS)

    Komarala, Vamsi K.; Rakovich, Yury P.; Bradley, A. Louise; Byrne, Stephen J.; Corr, Serena A.; Gun'ko, Yurii K.

    2006-08-01

    We present steady state and time-resolved photoluminescence (PL) characteristics of differently charged CdTe quantum dots (QDs) adsorbed onto a polyelectrolyte (PE) multilayer. The PE multilayer is built up using a layer-by-layer assembly technique. We find that the diffusion of the QDs into the PE multilayer is an important factor in the case of 3-mercapto-1, 2-propanediol stabilized QDs (neutral surface charge), resulting in a ~31-fold enhancement in PL intensity accompanied by a blue shift in the PL spectra and an increase in decay lifetime from 3.74 ns to a maximum of 11.65 ns. These modified emission properties are attributed to the enhanced surface related emission resulting from the interaction of the QD's surface with the PE. We find that diffusion does not occur for thioglycolic acid (TGA) stabilized QDs (negative surface charge) or 2-mercaptoethylamine stabilized QDs (positive surface charge), indicating localization of the QDs on top of the PE multilayer. However, the PL lifetime of the TGA stabilized QDs decreases from 9.58 to 5.78 ns with increasing PE multilayer thickness. This provides evidence for increased intrinsic exciton recombination relative to surface related emission, which results in an overall reduction in the average lifetime. Our studies indicate the importance of the QD surface charge in determining the interaction with the PE multilayers and the subsequent modification of the QD emission properties.

  11. Desktop aligner for fabrication of multilayer microfluidic devices

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

    2015-07-01

    Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 ?m cm-1. To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices.

  12. 76 FR 33782 - Multilayered Wood Flooring From China; Scheduling of the Final Phase of Countervailing Duty and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-09

    ...and 731-TA-1179 Final] Multilayered Wood Flooring From China; Scheduling of the...less-than-fair-value imports from China of multilayered wood flooring (``MLWF''), provided for...subject merchandise as `` * * * multilayered wood flooring, composed of an assembly of...

  13. 78 FR 52502 - Multilayered Wood Flooring From the People's Republic of China: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ...Shipper Review for Multilayered Wood Flooring from the People's...Shipper Review of Multilayered Wood Flooring from the People's...Shipper Review for Multilayered Wood Flooring from the People's...reflect the exclusion of Davao Panels Enterprises' 2011...

  14. Highly uniform bipolar resistive switching characteristics in TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2} multilayer

    SciTech Connect

    Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue E-mail: wangbiao@mail.sysu.edu.cn; Micro and Nano Physics and Mechanics Research Laboratory, School of Physics and Engineering, Sun Yat-Sen University, 510275 Guangzhou ; Lin, S. P.; Sino-French Institute of Nuclear Engineering and Technology, Zhuhai Campus, Sun Yat-Sen University, Zhuhai 519082 ; Luo, J. M.; Wang, B. E-mail: wangbiao@mail.sysu.edu.cn; Li, Z. X.

    2013-12-23

    Nanoscale multilayer structure TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2} has been fabricated on Pt/Ti/SiO{sub 2}/Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2}/Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO{sub 2} play a crucial role in the resistive switching phenomenon and the introduced TiO{sub 2}/BaTiO{sub 3} interfaces result in the high uniformity of bipolar resistive switching characteristics.

  15. Osseointegration of a hydroxyapatite-coated multilayered mesh stem.

    PubMed

    Kusakabe, Hiroshi; Sakamaki, Toyonori; Nihei, Kotaro; Oyama, Yasuo; Yanagimoto, Shigeru; Ichimiya, Masaru; Kimura, Jun; Toyama, Yoshiaki

    2004-07-01

    A new type of porous coating for hip prostheses called "multilayered mesh" was tested under weight-bearing conditions. The surface of the stem is constructed of titanium mesh produced by etching. The hip stems of hydroxyapatite (HA)-coated multilayered mesh and conventional beads were implanted into canine right hips, and animals were killed 3, 6 and 10 weeks and 6 and 12 months after implantation. Shear strength between the implant and the bone was evaluated by the push-out test. Bone ingrowth was calculated from backscattered electron imaging-scanning electron microscopy (BEI-SEM) images of transverse sections. Toluidine blue stained sections and the BEI-SEM images were evaluated histologically. The break sites of the specimens after the push-out test were evaluated on BEI-SEM images of longitudinal sections. The mean push-out strength of the HA-coated multilayered mesh samples was greater than that of the beads-coated samples every time tested, and the HA-coated multilayered mesh implants had significantly stronger push-out strength at 3 and 6 weeks (p<0.05). The strength of the HA-coated multilayered mesh implants was even greater at 6 and 12 months, whereas the strength of the beads-coated samples decreased. The HA-coated multilayered mesh implants showed significantly higher percentages of bone ingrowth than the beads-coated implants every time tested, except at 6 months (p<0.05). At 6 and 12 months, the bone ingrowth data for the HA-coated multilayered mesh implants increased, whereas it decreased for the beads-coated implants. The new bone formation had reached the bottom of the porous area of the HA-coated multilayered mesh surface by 3 weeks, but not had reached the bottom of the conventional beads surface. At 6 and 12 months, the smaller pores of the bead surface stopped the thickening of trabecular bone, and at 12 months, the break sites were at the bone-implant interface of the bead surface, whereas they were on the bone side of the HA-coated multilayered mesh surface. The difference between the break sites was significant at 12 months (p<0.05). The HA-coated multilayered mesh stem provided faster, stronger, and more durable osseointegration than the conventional bead stem. PMID:14967528

  16. Effect of La2O3 addition on interface chemistry between 4YSZ top layer and Ni based alloy bond coat in thermal barrier coating by EB PVD.

    PubMed

    Park, Chan-Young; Yang, Young-Hwan; Kim, Seong-Won; Lee, Sung-Min; Kim, Hyung-Tae; Jang, Byung-Koog; Lim, Dae-Soon; Oh, Yoon-Suk

    2014-11-01

    The effect of a 5 mol% La2O3 addition on the forming behavior and compositional variation at interface between a 4 mol% Yttria (Y2O3) stabilized ZrO2 (4YSZ) top coat and bond coat (NiCrAlY) as a thermal barrier coating (TBC) has been investigated. Top coats were deposited by electron beam physical vapor deposition (EB PVD) onto a super alloy (Ni-Cr-Co-Al) substrate without pre-oxidation of the bond coat. Top coats are found to consist of dense columnar grains with a thin interdiffusion layer between metallic bond coats. In the as-received 4YSZ coating, a thin interdiffusion zone at the interface between the top and bond coats was found to consist of a Ni-Zr intermetallic compound with a reduced quantity of Y, Al or O elements. On the other hand, in the case of an interdiffusion area of 5 mol% La2O3-added 4YSZ coating, it was found that the complicated composition and structure with La-added YSZ and Ni-Al rich compounds separately. The thermal conductivity of 5 mol% La2O3-added 4YSZ coating (- 1.6 W/m x k at 1100 degrees C) was lower than a 4YSZ coating (- 3.2 W/m x k at 1100 degrees C) alone. PMID:25958580

  17. Highly conductive and electrochemically stable plasticized blend polymer electrolytes based on PVdF-HFP and triblock copolymer PPG-PEG-PPG diamine for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Saikia, Diganta; Wu, Hao-Yiang; Pan, Yu-Chi; Lin, Chi-Pin; Huang, Kai-Pin; Chen, Kan-Nan; Fey, George T. K.; Kao, Hsien-Ming

    2011-03-01

    A new plasticized poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP)/PPG-PEG-PPG diamine/organosilane blend-based polymer electrolyte system has been synthesized and characterized. The structural and electrochemical properties of the electrolytes thus obtained were systematically investigated by a variety of techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile test, Fourier transform infrared spectroscopy (FTIR), 13C and 29Si solid-state NMR, AC impedance, linear sweep voltammetry (LSV) and charge-discharge measurements. The FTIR and NMR results provided the information about the interaction among the constituents in the blend polymer membrane. The present blend polymer electrolyte exhibits several advantageous electrochemical properties such as ionic conductivity up to 1.3 × 10-2 S cm-1 at room temperature, high value of Li+ transference number (t+ = 0.82), electrochemical stability up to 6.4 V vs. Li/Li+ with the platinum electrode, and stable charge-discharge cycles for lithium-ion batteries.

  18. 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

  19. Talin determines the nanoscale architecture of focal adhesions.

    PubMed

    Liu, Jaron; Wang, Yilin; Goh, Wah Ing; Goh, Honzhen; Baird, Michelle A; Ruehland, Svenja; Teo, Shijia; Bate, Neil; Critchley, David R; Davidson, Michael W; Kanchanawong, Pakorn

    2015-09-01

    Insight into how molecular machines perform their biological functions depends on knowledge of the spatial organization of the components, their connectivity, geometry, and organizational hierarchy. However, these parameters are difficult to determine in multicomponent assemblies such as integrin-based focal adhesions (FAs). We have previously applied 3D superresolution fluorescence microscopy to probe the spatial organization of major FA components, observing a nanoscale stratification of proteins between integrins and the actin cytoskeleton. Here we combine superresolution imaging techniques with a protein engineering approach to investigate how such nanoscale architecture arises. We demonstrate that talin plays a key structural role in regulating the nanoscale architecture of FAs, akin to a molecular ruler. Talin diagonally spans the FA core, with its N terminus at the membrane and C terminus demarcating the FA/stress fiber interface. In contrast, vinculin is found to be dispensable for specification of FA nanoscale architecture. Recombinant analogs of talin with modified lengths recapitulated its polarized orientation but altered the FA/stress fiber interface in a linear manner, consistent with its modular structure, and implicating the integrin-talin-actin complex as the primary mechanical linkage in FAs. Talin was found to be ?97 nm in length and oriented at ?15° relative to the plasma membrane. Our results identify talin as the primary determinant of FA nanoscale organization and suggest how multiple cellular forces may be integrated at adhesion sites. PMID:26283369

  20. Nanoscale material design for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Bao, Hua

    Solar cell technology directly converts the clean, abundant energy of the sun into electricity. To build solar cell modules with low cost and high energy conversion efficiency, nanomaterials such as nanowires, nanotubes and quantum dots are very promising candidates, due to their novel thermal, electrical, and optical properties. This research seeks to use silicon nanowire, carbon nanotube, and semiconductor quantum dot to achieve high optical absorption and low electron-phonon coupling. Multiscale simulation and experiments are combined to investigate the thermal radiative properties of nanowire/nanotube array structures and the electron-phonon interaction in semiconductor quantum dots. Optical properties of nanowire/nanotube structures are numerically investigated by combined ab initio calculation and computational electromagnetic calculations. At the atomic scale, ab initio calculations based on density functional theory are performed to evaluate the spectral dielectric function of the material using the initial atomic structure as the only input parameter. This method considers different absorption mechanisms from far infrared to visible spectrum, and its effectiveness is demonstrated using the material GaAs and small carbon nanotubes. At the nanoscale, the predicted dielectric function of nanowire/nanotube is used as an input parameter in finite-difference time-domain method, so that the optical properties of devices such as nanowire/nanotube arrays can be obtained. Based on this scheme, we have shown that the vertically aligned multiwalled carbon nanotube arrays are nearly perfect absorber in the visible spectrum. Silicon nanowire arrays are less absorptive than carbon nanotube, but we propose and demonstrate that their optical absorption can be greatly enhanced by introducing structural randomness, including random positioning, diameter and length. The enhanced optical absorption implies potential enhancement of the overall efficiency of nanotube/nanowire array solar cells. Phonon-assisted electron decay in semiconductor quantum dots is also investigated in this work. In semiconductor solar cell, a large portion of energy loss is by the fast hot electron cooling, in which a high energy electron decays to the electronic band gap by creating a series of phonons. The excessive electrical energy is then converted to heat and wasted, so that the total photovoltaic energy conversion efficiency is limited. The electron decay rate reduces in semiconductor quantum dots, due to the discrete electron energy levels created by quantum confinement. To design quantum dots with the slowest decay rate, we use the non-adiabatic molecular dynamics to perform real-time simulations of the phonon-assisted electron decay process. This method is based on time-dependent density functional theory, and can directly predict the phonon-assisted electron decay time using the initial quantum dot structure as the only input. The numerical simulation shows that the phonon-induced electron decay can be slowed down in a small PbSe quantum dot. The temperature-dependent relaxation in this quantum dot is also studied, which helps us to propose a multi-channel relaxation mechanism. This mechanism provides new insights to the understanding of electron decay process in quantum dots. The results from this study have potentially important applications in solar energy harvesting and radiative thermal management. It offers a new perspective of nanoscale engineering of materials to achieve more efficient photovoltaic energy conversion.

  1. 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

  2. 77 FR 13159 - Nanoscale Science, Engineering, and Technology Subcommittee of the Committee on Technology...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ... TECHNOLOGY POLICY Nanoscale Science, Engineering, and Technology Subcommittee of the Committee on Technology, National Science and Technology Council Workshop ACTION: Notice of public meeting. SUMMARY: The National Nanotechnology Coordination Office (NNCO), on behalf of the Nanoscale Science, Engineering, and Technology...

  3. Three-dimensional model of strength and ductility of polycrystalline copper containing nanoscale twins

    E-print Network

    Dao, Ming

    Three-dimensional model of strength and ductility of polycrystalline copper containing nanoscale similar to those observed in nanocrystalline metals can be obtained without a severe deterioration in ductility. This is achieved by introducing controlled, nanoscale, growth twins within ultrafine

  4. The Performance of Gas Filled Multilayer Insulation

    NASA Astrophysics Data System (ADS)

    Mills, G. L.; Zeller, C. M.

    2008-03-01

    The NASA Exploration Program is currently planning to use liquid oxygen, methane and hydrogen for propulsion in future spacecraft for the human exploration of the Moon and Mars. This will require the efficient long term, on-orbit storage of these cryogens. Multilayer insulation (MLI) will be critical to achieving the required thermal performance since it has much lower heat transfer than any other insulation when used in a vacuum. However, the size and mass constraints of these propulsion systems will not allow a structural shell to be used to provide vacuum for the MLI during ground hold and launch. One approach is to purge the MLI during ground hold with an inert gas which is then vented during launch ascent and on-orbit. In this paper, we report on experimental tests and modeling that we have done on MLI used to insulate a cryogenic tank. These include measurements of the heat transfer of gas filled insulation, evacuated insulation and during the transition in between.

  5. Cryogenic Cermic Multilayer Capacitors for Power Electronics

    NASA Astrophysics Data System (ADS)

    Alberta, E. F.; Hackenberger, W. S.

    2006-03-01

    Recent advances in the areas of high temperature superconductors and low temperature MOSFET devices have opened the door to the possibility of developing highly efficient low-temperature power electronics. The most commonly used high-efficiency capacitors are based on high dielectric constant (K ˜ 1000-4000) barium titanate doped to yield and X7R temperature dependence (±15% change in capacitance from -55°C to 125°C); however, below their minimum use temperature the capacitance drops-off quickly leading to a low volumetric efficiency and high temperature coefficient of capacitance (TCC) at cryogenic temperatures. A series of low temperature materials with moderate to high dielectric constants have been specifically developed for low temperature operation (below 80K). The capacitors fall into three main categories: low TCC, high volumetric efficiency, and energy storage. In the low TCC category, co-fired multilayer ceramic capacitors (MLCCs) were fabricated with capacitance values up to 62nF at 30K, TCCs from 0.9 to 2% below 80K, and losses on the order of 0.0001. In the high volumetric efficiency category, dielectrics with permittivities ranging from 1,000 to 30,000 were demonstrated.

  6. Nonlinear acoustic effects in multilayer ceramic capacitors

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Kim, S. A.; Quinn, T. P.; White, G. S.

    2013-01-01

    Nonlinear resonant acoustics was explored as an approach for nondestructively evaluating the susceptibility of BaTiO3-based multilayer ceramic capacitors to electrical failure during service. The acoustic nonlinearity was characterized through measurements of the dependence of the frequency of a selected dominant mode near 1.16 MHz on driving amplitude, employing direct ferroelectric tone-burst transduction, time-domain signal acquisition, and frequency-domain spectral analysis. Finite-element modeling and consideration of the symmetry of the excitation led to identification of the selected mode as the lowest-order extensional mode. Measurements as a function of the number of thermal treatments (of two types) provided evidence for increases in acoustic nonlinearity arising from thermal-stress-induced material damage. No evidence for further systematic changes in nonlinearity was found after nine heat treatments. Signals and analysis for some samples were complicated by the emergence of a second resonance in the waveforms and an apparent reduction in acoustic nonlinearity as a function of time under DC bias. The second of these effects is suggested as being associated with changes in nonlinear elements of the material (presumably, microcracks) that arise from interactions of internal stresses during domain reorientation.

  7. Robust Multilayer Insulation for Cryogenic Systems

    NASA Technical Reports Server (NTRS)

    Fesmire, J. E.; Scholtens, B. F.; Augustynowicz, S. D.

    2007-01-01

    New requirements for thermal insulation include robust Multilayer insulation (MU) systems that work for a range of environments from high vacuum to no vacuum. Improved MLI systems must be simple to install and maintain while meeting the life-cycle cost and thermal performance objectives. Performance of actual MLI systems has been previously shown to be much worse than ideal MLI. Spacecraft that must contain cryogens for both lunar service (high vacuum) and ground launch operations (no vacuum) are planned. Future cryogenic spacecraft for the soft vacuum environment of Mars are also envisioned. Industry products using robust MLI can benefit from improved cost-efficiency and system safety. Novel materials have been developed to operate as excellent thermal insulators at vacuum levels that are much less stringent than the absolute high vacuum requirement of current MLI systems. One such robust system, Layered Composite Insulation (LCI), has been developed by the Cryogenics Test Laboratory at NASA Kennedy Space Center. The experimental testing and development of LCI is the focus of this paper. LCI thermal performance under cryogenic conditions is shown to be six times better than MLI at soft vacuum and similar to MLI at high vacuum. The experimental apparent thermal conductivity (k-value) and heat flux data for LCI systems are compared with other MLI systems.

  8. Epidemic Model with Isolation in Multilayer Networks

    NASA Astrophysics Data System (ADS)

    Zuzek, L. G. Alvarez; Stanley, H. E.; Braunstein, L. A.

    2015-07-01

    The Susceptible-Infected-Recovered (SIR) model has successfully mimicked the propagation of such airborne diseases as influenza A (H1N1). Although the SIR model has recently been studied in a multilayer networks configuration, in almost all the research the isolation of infected individuals is disregarded. Hence we focus our study in an epidemic model in a two-layer network, and we use an isolation parameter w to measure the effect of quarantining infected individuals from both layers during an isolation period tw. We call this process the Susceptible-Infected-Isolated-Recovered (SIIR) model. Using the framework of link percolation we find that isolation increases the critical epidemic threshold of the disease because the time in which infection can spread is reduced. In this scenario we find that this threshold increases with w and tw. When the isolation period is maximum there is a critical threshold for w above which the disease never becomes an epidemic. We simulate the process and find an excellent agreement with the theoretical results.

  9. Pattern inspection of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2015-07-01

    Patterned mask inspection for an etched multilayer (ML) EUV mask was investigated. In order to optimize the mask structure from the standpoint of not only a pattern inspection by using a projection electron microscope (PEM), but also by considering the other fabrication processes using electron beam (EB) techniques such as CD metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients (SEECs) of the candidate materials for conductive layer, we evaluated the image contrast and the influence of charging effect. In the cases of 40-pair-ML, 16 nm sized extrusion and intrusion defects were found to be detectable more than 10 sigma in hp 44 nm, 40 nm, and 32 nm line and space (L/S) patterns. Reducing 40-pair-ML to 20-pair-ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16 nm sized defects remained detectable. A double layer structure with 2.5-nm-thik B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  10. Integrated and Load Responsive Multilayer Insulation

    NASA Astrophysics Data System (ADS)

    Dye, S.; Kopelove, A.; Mills, G. L.

    2010-04-01

    Multilayer insulation (MLI) is used to reduce heat leak into cryogenic systems such as tanks, dewars and instruments, and used to control spacecraft heat leak. MLI is typically used in a high vacuum (<10-3 Pa) where its performance usually exceeds other insulations by 10-fold. Conventional MLI consists of layers of low thermal emissivity metalized polymer sheets separated by low conductance netting spacers. We report on an improved MLI in which the spacer netting is replaced by micro-molded polymer parts with low thermal conductance that provide controlled layer spacing. Integrated MLI (IMLI) is a precisely engineered insulation system with advantages over conventional MLI, including higher performance, more predictable performance, more robust, lower particulate contamination, optional electrical conduction and lower cost. A second novel insulation, Load Responsive MLI (LRMLI) is described which uses polymer spacers that dynamically respond to load, compressing to support a thin, lightweight vacuum shell under one atmosphere external pressure, and decompressing under reduced atmospheric pressure or vacuum for lower heat leak. Structural and thermal analysis and testing results are presented. IMLI and LRMLI performance are compared to conventional MLI and polymer Spray On Foam Insulation (SOFI).

  11. Progress at the ESRF multilayer facility

    NASA Astrophysics Data System (ADS)

    Morawe, Ch; Peffen, J. Ch; Friedrich, K.; Osterhoff, M.

    2013-03-01

    The ESRF multilayer (ML) deposition facility is fully operational since 2009. By the end of 2011, almost 50 ML projects were completed using the new machine, bringing the total number to 143 since 1998. Thanks to the new equipment and its improved performance the throughput could be significantly increased. The ESRF upgrade project caused strong demands for new ML optics, in particular dynamically bent KB focusing devices requiring very precise and steeply graded ML coatings. Thanks to this technology, the ESRF nano-imaging end-station ID22NI now provides the users with spot sizes of the order of 50×50 nm2 at a photon flux of 1012 ph/s. Among various in-house research and development activities the study of stress evolution during thin film and ML growth will be highlighted. Additional projects involving a PhD student and a PostDoc fellow cover the fields of wave optical simulations using curved MLs and the exposure of ML based monochromators to the white beam.

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

    NASA Astrophysics Data System (ADS)

    Boseman, Adam J.

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

  13. Flexible nanoscale high-performance FinFETs.

    PubMed

    Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

  14. Reduction of Thermal Conductivity by Nanoscale 3D Phononic Crystal

    PubMed Central

    Yang, Lina; Yang, Nuo; Li, Baowen

    2013-01-01

    We studied how the period length and the mass ratio affect the thermal conductivity of isotopic nanoscale three-dimensional (3D) phononic crystal of Si. Simulation results by equilibrium molecular dynamics show isotopic nanoscale 3D phononic crystals can significantly reduce the thermal conductivity of bulk Si at high temperature (1000?K), which leads to a larger ZT than unity. The thermal conductivity decreases as the period length and mass ratio increases. The phonon dispersion curves show an obvious decrease of group velocities in 3D phononic crystals. The phonon's localization and band gap is also clearly observed in spectra of normalized inverse participation ratio in nanoscale 3D phononic crystal. PMID:23378898

  15. Modeling nanoscale hydrodynamics by smoothed dissipative particle dynamics

    SciTech Connect

    Lei, Huan; Mundy, Christopher J.; Schenter, Gregory K.; Voulgarakis, Nikolaos

    2015-05-21

    Thermal fluctuation and hydrophobicity are two hallmarks of fluid hydrodynamics on the nano-scale. It is a challenge to consistently couple the small length and time scale phenomena associated with molecular interaction with larger scale phenomena. The development of this consistency is the essence of mesoscale science. In this study, we develop a nanoscale fluid model based on smoothed dissipative particle dynamics that accounts for the phenomena of associated with density fluctuations and hydrophobicity. We show consistency in the fluctuation spectrum across scales. In doing so, it is necessary to account for finite fluid particle size. Furthermore, we demonstrate that the present model can capture of the void probability and solvation free energy of apolar particles of different sizes. The present fluid model is well suited for a understanding emergent phenomena in nano-scale fluid systems.

  16. Plasmonic nanoantennas: enhancing light-matter interactions at the nanoscale

    E-print Network

    Patel, Shobhit K

    2015-01-01

    The research area of plasmonics promises devices with ultrasmall footprint operating at ultrafast speeds and with lower energy consumption compared to conventional electronics. These devices will operate with light and bridge the gap between microscale dielectric photonic systems and nanoscale electronics. Recent research advancements in nanotechnology and optics have led to the creation of a plethora of new plasmonic designs. Among the most promising are nanoscale antennas operating at optical frequencies, called nanoantennas. Plasmonic nanoantennas can provide enhanced and controllable light-matter interactions and strong coupling between far-field radiation and localized sources at the nanoscale. After a brief introduction of several plasmonic nanoantenna designs and their well-established radio-frequency antenna counterparts, we review several linear and nonlinear applications of different nanoantenna configurations. In particular, the possibility to tune the scattering response of linear nanoantennas and...

  17. Optimum design of a nanoscale spin-Seebeck power device

    NASA Astrophysics Data System (ADS)

    Liao, Tianjun; Lin, Jian; Su, Guozhen; Lin, Bihong; Chen, Jincan

    2015-04-01

    A theoretical model of a nanoscale spin-Seebeck power device (SSPD) is proposed based on the longitudinal spin-Seebeck effect in bilayers made of a ferromagnetic insulator and a normal metal. Expressions for the power output and thermal efficiency of the SSPD are derived analytically. The performance characteristics of the nanoscale SSPD are analyzed using numerical simulation. The maximum power output density and efficiency are calculated numerically. The effect of the spin Hall angle on the performance characteristics of the SSPD is analyzed. The choice of materials and the structure of the device are discussed. The optimum criteria of some key parameters of the SSPD, such as the power output density, efficiency, thickness of the normal metal, and the load resistance, are given. The results obtained here could provide a theoretical basis for the optimal design and operation of nanoscale SSPDs.

  18. Hydrodynamic Modeling of Heat Conduction in Nanoscale Systems.

    PubMed

    Dong, Yuan; Guo, Zeng-Yuan

    2015-04-01

    Heat conduction in nanoscale systems has different behavior from bulk materials, which is applied to develop high performance thermoelectric material. The non-trivial behavior is caused by the ballistic-diffusive transport of heat carriers such as phonons. In this paper, we use the thermomass theory and phonon hydrodynamics model to establish a hydrodynamic model for phonon transport. In nanoscale systems, a Poiseuille flow of phonon gas is formed due to the boundary scattering. The thickness of boundary layer is proportional to the mean free paths of phonon. When the boundary layer thickness is comparable with the whole flow region, strong decrease of effective thermal conductivity happens. This method can serve as a fast evaluation method for nanoscale heat conduction. PMID:26353568

  19. Nanoscale Phase Transitions under Extreme Conditions within an Ion Track

    SciTech Connect

    Zhang, Jiaming; Lang, Maik; Ewing, Rodney C.; Devanathan, Ramaswami; Weber, William J.; Toulemonde, Marcel

    2010-06-30

    The dynamics of track development due to the passage of relativistic heavy ions through solids is a long-standing issue relevant to nuclear materials, age-dating of minerals, space exploration, and nanoscale fabrication of novel devices. We have integrated experimental and simulation approaches to investigate nanoscale phase transitions under the extreme conditions created within single tracks of relativistic ions in Gd2O3(TiO2)x and Gd2Zr2-xTixO7. Track size and internal structure depend on energy-density deposition, irradiation temperature, and material composition. Molecular dynamics methods based on the thermal spike model have simulated, for the first time, the internal structure of individual tracks, consistent with experimental observations. Individual ion tracks have nanoscale core-shell structures that provide a unique record of the phase transition pathways under extreme conditions.

  20. Nanoscale Phase Transitions under Extreme Conditions within an Ion Track

    SciTech Connect

    Zhang, Jiaming; Lang, Maik; Ewing, Rodney C.; Devanathan, R.; Weber, William; Toulemonde, M.

    2011-01-31

    The dynamics of track development due to the passage of relativistic heavy ions through solids is a long-standing issue relevant to nuclear materials, age dating of minerals, space exploration, and nanoscale fabrication of novel devices. We have integrated experimental and simulation approaches to investigate nanoscale phase transitions under the extreme conditions created within single tracks of relativistic ions in Gd{sub 2}O{sub 3}(TiO{sub 2}){sub x} and Gd{sub 2}Zr{sub 2–x} Ti{sub x} O{sub 7}. Track size and internal structure depend on energy density deposition, irradiation temperature, and material composition. Based on the inelastic thermal spike model, molecular dynamics simulations follow the time evolution of individual tracks and reveal the phase transition pathways to the concentric track structures observed experimentally. Individual ion tracks have nanoscale core-shell structures that provide a unique record of the phase transition pathways under extreme conditions.