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Sample records for metallic nanoshell composites

  1. Fabrication of metal nanoshells

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, Jr., James R. (Inventor)

    2012-01-01

    Metal nanoshells are fabricated by admixing an aqueous solution of metal ions with an aqueous solution of apoferritin protein molecules, followed by admixing an aqueous solution containing an excess of an oxidizing agent for the metal ions. The apoferritin molecules serve as bio-templates for the formation of metal nanoshells, which form on and are bonded to the inside walls of the hollow cores of the individual apoferritin molecules. Control of the number of metal atoms which enter the hollow core of each individual apoferritin molecule provides a hollow metal nonparticle, or nanoshell, instead of a solid spherical metal nanoparticle.

  2. Electronic structure and polarizability of metallic nanoshells

    Science.gov (United States)

    Prodan, E.; Nordlander, P.

    2002-01-01

    An efficient method for the calculation of the electronic structure of metallic nanoshells is developed. The method is applied to a large nanoshell (of 10 nm in diameter) containing more than 2.5×10 4 conduction electrons. The calculations show that the density of states of the nanoshell is relatively bulk-like. The frequency dependent polarizability is calculated and shown to display strong confinement effects and features similar to what is predicted by semi-classical electrodynamic theory.

  3. Optical resonance of metal-coated nanoshell

    Institute of Scientific and Technical Information of China (English)

    Diao Jia-Jie(刁佳杰); Chen Guang-De(陈光德); Xi Cong(席聪); Z Y Fan; Yuan Jin-She(苑进社)

    2003-01-01

    Metal-coated nanoshell, the nanoparticle consisting of a nanometre-scale dielectric core coated with a thin metallic shell, exhibits three distinct optical resonant forms, the sphere cavity resonance (SCR), plasmon resonance (PR), and concentric dielectric sphere resonance (CDSR). The SCR, PR and CDSR of the metal-coated nanoshell reveal a geometric tunability controlled by the core radius and by the ratio of the core radius to the total radius. Classical electrodynamics and Mie scattering theory are used to treat the resonant forms and the transition state between the resonant forms. Based on previous experimental research, we present a group of resonant equations for all the resonant forms, which depend on the geometric structure of the metal-coated nanoshell.

  4. Surface plasmon lifetime in metal nanoshells

    Science.gov (United States)

    Kirakosyan, Arman S.; Stockman, Mark I.; Shahbazyan, Tigran V.

    2016-10-01

    The lifetime of localized surface plasmon plays an important role in many aspects of plasmonics and its applications. In small metal nanostructures, the dominant mechanism of plasmon decay is size-dependent Landau damping. We performed quantum-mechanical calculations of Landau damping for the bright surface plasmon mode in a metal nanoshell with dielectric core. In contrast to the conventional model based on the electron surface scattering, we found that the damping rate decreases as the nanoshell thickness is reduced. The origin of this behavior is traced to the spatial distribution of plasmon local field in the metal shell. We also found that, due to the interference of electron scattering amplitudes from the two nanoshell metal surfaces, the damping rate exhibits pronounced quantum beats with changing shell thickness.

  5. Plasmonic nanoshell synthesis in microfluidic composite foams.

    Science.gov (United States)

    Duraiswamy, Suhanya; Khan, Saif A

    2010-09-01

    The availability of robust, scalable, and automated nanoparticle manufacturing processes is crucial for the viability of emerging nanotechnologies. Metallic nanoparticles of diverse shape and composition are commonly manufactured by solution-phase colloidal chemistry methods, where rapid reaction kinetics and physical processes such as mixing are inextricably coupled, and scale-up often poses insurmountable problems. Here we present the first continuous flow process to synthesize thin gold "nanoshells" and "nanoislands" on colloidal silica surfaces, which are nanoparticle motifs of considerable interest in plasmonics-based applications. We assemble an ordered, flowing composite foam lattice in a simple microfluidic device, where the lattice cells are alternately aqueous drops containing reagents for nanoparticle synthesis or gas bubbles. Microfluidic foam generation enables precisely controlled reagent dispensing and mixing, and the ordered foam structure facilitates compartmentalized nanoparticle growth. This is a general method for aqueous colloidal synthesis, enabling continuous, inherently digital, scalable, and automated production processes for plasmonic nanomaterials.

  6. Metallic nanoshells on porphyrin-stabilized emulsions

    Science.gov (United States)

    Wang, Haorong; Song, Yujiang; Shelnutt, John A; Medforth, Craig J

    2013-10-29

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  7. Tunable hybridization in metal nanoshell chains.

    Science.gov (United States)

    Ling, C W; Zheng, M J; Yu, K W

    2011-03-16

    We have studied the coupled surface plasmon (SP) modes in periodic metal nanoshell chains by including long range electromagnetic interactions. The eigen-decomposition method is used to analyze the dispersion and dissipation of the SP modes. The resulting band structure can be understood as a hybridization between a hole band and a particle band with a structurally tunable band gap in the middle of the first Brillouin zone. The mode quality, which is defined as the imaginary part of the generalized polarizability, increases as the shell thickness decreases. This indicates a larger energy loss and an increasing coupling between the bands. Through the manipulation of the band structures, the propagation of the coupled SP modes in the nanoshell chain can be controlled.

  8. Tunable hybridization in metal nanoshell chains

    Energy Technology Data Exchange (ETDEWEB)

    Ling, C W; Zheng, M J; Yu, K W, E-mail: mjzheng@phy.cuhk.edu.hk [Department of Physics, Chinese University of Hong Kong, Shatin, New Territories (Hong Kong)

    2011-03-16

    We have studied the coupled surface plasmon (SP) modes in periodic metal nanoshell chains by including long range electromagnetic interactions. The eigen-decomposition method is used to analyze the dispersion and dissipation of the SP modes. The resulting band structure can be understood as a hybridization between a hole band and a particle band with a structurally tunable band gap in the middle of the first Brillouin zone. The mode quality, which is defined as the imaginary part of the generalized polarizability, increases as the shell thickness decreases. This indicates a larger energy loss and an increasing coupling between the bands. Through the manipulation of the band structures, the propagation of the coupled SP modes in the nanoshell chain can be controlled.

  9. Metal Nanoshells for Enhanced Solar-to-Fuel Photocatalytic Conversion

    Science.gov (United States)

    2011-09-20

    presence of metal nanoshells can absorb the solar energy in the IR range. However, the broad absorption of metal nanoshells also covered the visible...solar to heat), and photosynthesis (solar to fuel). In the latter technology, artificial photosynthesis mimics natural photosynthesis by converting...high enough to reduce water. (AgIn)xZnyS2x+y solid solution, derived from ZnS is a narrower band gap semiconductor. The absorption of the solid

  10. Metal enhanced fluorescence of Ag-nanoshell dimer

    Science.gov (United States)

    Liaw, Jiunn-Woei; Chen, Huang-Chih; Chen, Bae-Renn; Kuo, Mao-Kuen

    2014-04-01

    The plasmon modes of Ag-nanoshell dimer on metal enhanced fluorescence (MEF) are studied theoretically. The amplified excitation rate of a dimer (two identical Ag nanoshells) illuminated by a plane wave for exciting a molecule located at the gap center is calculated. Subsequently, the apparent quantum yield of the emission of the excited molecule affected by the dimer is investigated. The multiple multipole method is used for the both simulations. Finally, the enhancement factor of the dimer on the overall photoluminescence of the molecule in terms of the two parameters is evaluated. Our results show that Ag-nanoshell dimer is a dual-band photoluminescence enhancer for MEF at the bonding dipole and quadrupole modes. The former is broadband, and the latter narrowband. Both bands depend on the gap size. Moreover, the average enhancement factor of Ag-nanoshell dimer for MEF with a Stokes shift is discussed.

  11. Coherent acoustic vibration of metal nanoshells.

    Science.gov (United States)

    Guillon, C; Langot, P; Del Fatti, N; Vallée, F; Kirakosyan, A S; Shahbazyan, T V; Cardinal, T; Treguer, M

    2007-01-01

    Using time-resolved pump-probe spectroscopy, we have performed the first investigation of the vibrational modes of gold nanoshells. The fundamental isotropic mode launched by a femtosecond pump pulse manifests itself in a pronounced time-domain modulation of the differential transmission probed at the frequency of nanoshell surface plasmon resonance. The modulation amplitude is significantly stronger, and the period is longer than that in a gold nanoparticle of the same overall size, in agreement with theoretical calculations. This distinct acoustical signature of nanoshells provides a new and efficient method for identifying these versatile nanostructures and for studying their mechanical and structural properties.

  12. Synthesis of metallic nanoshells on porphyrin-stabilized emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haorong (Albuquerque, NM); Song, Yujiang (Albuquerque, NM); Shelnutt, John A. (Tijeras, NM); Medforth, Craig J. (Winters, CA)

    2011-12-13

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  13. Synthesis of metallic nanoshells on porphyrin-stabilized emulsions

    Science.gov (United States)

    Wang, Haorong [Albuquerque, NM; Song, Yujiang [Albuquerque, NM; Shelnutt, John A [Tijeras, NM; Medforth, Craig J [Winters, CA

    2011-12-13

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  14. Metastable alloy nanoparticles, metal-oxide nanocrescents and nanoshells generated by laser ablation in liquid solution: influence of the chemical environment on structure and composition.

    Science.gov (United States)

    Scaramuzza, Stefano; Agnoli, Stefano; Amendola, Vincenzo

    2015-11-14

    Alloy nanoparticles are characterized by the combination of multiple interesting properties, which are attractive for technological and scientific purposes. A frontier topic of this field is nanoalloys with compositions not thermodynamically allowed at ordinary temperature and pressure (i.e. metastable), because they require out-of-equilibrium synthetic approaches. Recently, laser ablation synthesis in solution (LASiS) was successfully applied for the realization of metastable nanoalloys because of the fast kinetics of nanoparticle formation. However, the role played by the chemical environment on the final composition and structure of laser generated nanoalloys still has to be fully elucidated. Here, we investigated the influence of different synthetic conditions on the LASiS of metastable nanoalloys composed of Au and Fe, such as the use of water instead of ethanol, the bubbling of inert gases and the addition of a few vol% of H2O2 and H2O. The two elements showed different reactivity when LASiS was performed in water instead of ethanol, while minor effects were observed from bubbling pure gases such as N2, Ar and CO2 in the liquid solution. Moreover, the plasmonic response and the structure of the nanoalloys were sensibly modified by adding H2O2 to water. We also found that nanoparticle production is dramatically influenced just by adding 0.2% of H2O in ethanol. These results suggest that the formation of a cavitation bubble with long lifetime and large size during LASiS is useful for the preservation of the metastable alloy composition, whereas an oxidative environment hampers the formation of metastable alloy nanoparticles. Overall, by acting on the type of solvent and solutes, we were able to switch from a traditional synthetic approach for the composition of Au-Fe nanoalloys to one using a reactive environment, which gives unconventional structures such as metal@iron-oxide nanoshells and nanocrescents of oxide supported on metal nanospheres. These results

  15. Collective plasmonic modes in ordered assemblies of metallic nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Tserkezis, C; Gantzounis, G; Stefanou, N [Section of Solid State Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens (Greece)], E-mail: ctserk@phys.uoa.gr

    2008-02-20

    Collective plasmonic modes in two- and three-dimensional periodic assemblies of metallic nanoshells are studied by means of full electrodynamic calculations using the layer-multiple-scattering method. We consider structures made of a single type of nanoshell as well as binary heterostructures made of two different types of nanoshells. The complex photonic band structure of such three-dimensional photonic crystals is analyzed in conjunction with relevant transmission diagrams of corresponding finite slabs and the physical origin of the different optical modes is elucidated. Moreover, we discuss associated absorption spectra and provide a consistent interpretation of the underlying physics. In the case of the binary systems, the plasmonic modes of the two building components coexist, leading to a rich structure of resonances over an extended frequency range and to broadband absorption.

  16. Composite Nanoshells for Enhanced Solar-to-Fuel Photocatalytic Conversion

    Science.gov (United States)

    2012-06-20

    films were measured. Secondly, we reported the novel synthesis of metal oxide (SiO2 and SnO2)-coated metal-metal nanoshells. These unique IR-absorption...Electrophoretic deposition. Figure 2. Photoelectrochemical reaction system. 4. Preparation of Silver nanoparticles (NPs) Silver NPs were prepared...filtered them through 0.22 μm membrane filter to remove the Ag nanorods . The SEM image (Figure 3) shows that the size of Ag NP is 60 ~ 80 nm

  17. Metal Nanoshells for Plasmonically Enhanced Solar-to-Fuel Photocatalytic Conversion

    Science.gov (United States)

    2014-05-09

    Final 3. DATES COVERED (From - To) 04/16/2013 – 04/15/2014 4. TITLE AND SUBTITLE Metal Nanoshells for Plasmonically Enhanced Solar-to...following experiments, the core-shell of nanoshell @SiO2, as well as the nanostructure of photocatalyst, were further investigated. Solar energy in the...visible-light range is expected to be absorbed by the photocatalyst first without any interference from the metal nanoshells . The presence of metal

  18. Composite material made of plasmonic nanoshells with quantum dot cores: loss-compensation and ε-near-zero physical properties.

    Science.gov (United States)

    Campione, Salvatore; Capolino, Filippo

    2012-06-15

    A theoretical investigation of loss-compensation capabilities in composite materials made of plasmonic nanoshells is carried out by considering quantum dots (QDs) as the nanoshells' cores. The QD and metal permittivities are modeled according to published experimental data. We determine the modes with real or complex wavenumber able to propagate in a 3D periodic lattice of nanoshells. Mode analysis is also used to assess that only one propagating mode is dominant in the composite material whose optical properties can hence be described via homogenization theory. Therefore, the material effective permittivity is found by comparing different techniques: (i) the mentioned mode analysis, (ii) Maxwell Garnett mixing rule and (iii) the Nicolson-Ross-Weir method based on transmission and reflection when considering a metamaterial of finite thickness. The three methods are in excellent agreement, because the nanoshells considered in this paper are very subwavelength, thus justifying the parameter homogenization. We show that QDs are able to provide loss-compensated ε-near-zero metamaterials and also loss-compensated metamaterials with large negative values of permittivity. Besides compensating for losses, the strong gain via QD can provide optical amplification with particular choices of the nanoshell and lattice dimensions.

  19. Time-dependent density functional calculation of the energy loss of antiprotons colliding with metallic nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Quijada, M. [Departamento de Fisica de Materiales, Facultad de Quimicas UPV/EHU, Apartado 1072, 20080 San Sebastian (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Borisov, A.G. [Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Universite Paris-Sud, Laboratoire des Collisions Atomiques et Moleculaires (France); CNRS, UMR 8625, Laboratoire des Collisions Atomiques et Moleculaires, LCAM, Batiment 351, UPS-11, Orsay, 91405 Orsay Cedex (France); Muino, R.D. [Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Centro de Fisica de Materiales, Centro Mixto CSIC-UPV/EHU, Edificio Korta, Avenida de Tolosa 72, 20018 San Sebastian (Spain)

    2008-06-15

    Time-dependent density functional theory is used to study the interaction between antiprotons and metallic nanoshells. The ground state electronic properties of the nanoshell are obtained in the jellium approximation. The energy lost by the antiproton during the collision is calculated and compared to that suffered by antiprotons traveling in metal clusters. The resulting energy loss per unit path length of material in thin nanoshells is larger than the corresponding quantity for clusters. It is shown that the collision process can be interpreted as the antiproton crossing of two nearly bi-dimensional independent metallic systems. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Enhancement of oxygen reduction activity of nanoshell carbons by introducing nitrogen atoms from metal phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, Jun-ichi, E-mail: jozaki@cee.gunma-u.ac.j [Department of Chemical and Environmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Tanifuji, Shin-ichi; Furuichi, Atsuya; Yabutsuka, Katsutoshi [Department of Chemical and Environmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515 (Japan)

    2010-02-15

    Nanoshell carbon is a type of catalytically grown nanocarbon with a hollow, round, shell-like structure, with a diameter in the range of approximately 20-50 nm. It has been shown to possess the electrocatalytic activity for oxygen reduction reaction (ORR) and is also expected to be a non-Pt catalyst for polymer electrolyte fuel cells. This paper reports the synergetic enhancement of the ORR activity of nanoshell carbons caused by the coexistence of nitrogen atoms. The nanoshell carbons were prepared by the carbonization of furan resin in the presence of acetylacetonates (AAs) and of phthalocyanines (Pcs), which contained Fe, Co, and Ni. The Pc-derived nanoshells (MP-T series; M = Co or Fe, T = carbonization temperature) showed higher ORR activities than the AA-derived nanoshells (MA-T series; M = Co or Fe, T = carbonization temperature) when the same metal elements were employed. An XPS study revealed that nitrogen species were introduced to the surface of the nanoshells when Pcs were used as the nanoshell-forming catalysts, and that no metal species remained on the nanoshells. Principally, the ORR activity of the carbons was governed by the presence of the nanoshells and further enhancement could be achieved by the introduction of nitrogen atoms. 0.78 V of OCV and 0.21 W cm{sup -2} of the maximum power density were observed for a fuel cell whose MEA consisted of 3CoP1000 cathode and a commercial Pt/C anode, when it was operated at 80 deg. C under a pressurized condition of 0.35 MPa.

  1. Fluorescent metal nanoshell and CK19 detection on single cell image.

    Science.gov (United States)

    Zhang, Jian; Fu, Yi; Li, Ge; Lakowicz, Joseph R; Zhao, Richard Y

    2011-09-16

    In this article, we report the synthesis strategy and optical properties of a novel type of fluorescence metal nanoshell when it was used as imaging agent for fluorescence cell imaging. The metal nanoshells were made with 40 nm silica cores and 10nm silver shells. Unlike typical fluorescence metal nanoshells which contain the organic dyes in the cores, novel metal nanoshells were composed of Cy5-labelled monoclonal anti-CK19 antibodies (mAbs) on the external surfaces of shells. Optical measurements to the single nanoparticles showed that in comparison with the metal free labelled mAbs, the mAb-Ag complexes displayed significantly enhanced emission intensity and dramatically shortened lifetime due to near-field interactions of fluorophores with metal. These metal nanoshells were found to be able to immunoreact with target cytokeratin 19 (CK19) molecules on the surfaces of LNCAP and HeLa cells. Fluorescence cell images were recorded on a time-resolved confocal microscope. The emissions from the metal nanoprobes could be clearly isolated from the cellular autofluorescence backgrounds on the cell images as either individuals or small clusters due to their stronger emission intensities and shorter lifetimes. These emission signals could also be precisely counted on single cell images. The count number may provide an approach for quantifying the target molecules in the cells.

  2. Fluorescent metal nanoshell and CK19 detection on single cell image

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian, E-mail: jian@cfs.biomet.umaryland.edu [Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201 (United States); Fu, Yi [Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201 (United States); Li, Ge [Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Lakowicz, Joseph R. [Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201 (United States); Zhao, Richard Y., E-mail: rzhao@som.umaryland.edu [Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Department of Microbiology-Immunology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States); Institute of Human Virology, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201 (United States)

    2011-09-16

    Highlights: {yields} Novel metal nanoshell as fluorescence imaging agent. {yields} Fluorescent mAb-metal complex with enhanced intensity and shortened lifetime. {yields} Immuno-interactions of mAb-metal complexes with CK19 molecules on CNCAP and HeLa cell surfaces. {yields} Isolation of conjugated mAb-metal complexes from cellular autofluorescence on cell image. -- Abstract: In this article, we report the synthesis strategy and optical properties of a novel type of fluorescence metal nanoshell when it was used as imaging agent for fluorescence cell imaging. The metal nanoshells were made with 40 nm silica cores and 10 nm silver shells. Unlike typical fluorescence metal nanoshells which contain the organic dyes in the cores, novel metal nanoshells were composed of Cy5-labelled monoclonal anti-CK19 antibodies (mAbs) on the external surfaces of shells. Optical measurements to the single nanoparticles showed that in comparison with the metal free labelled mAbs, the mAb-Ag complexes displayed significantly enhanced emission intensity and dramatically shortened lifetime due to near-field interactions of fluorophores with metal. These metal nanoshells were found to be able to immunoreact with target cytokeratin 19 (CK19) molecules on the surfaces of LNCAP and HeLa cells. Fluorescence cell images were recorded on a time-resolved confocal microscope. The emissions from the metal nanoprobes could be clearly isolated from the cellular autofluorescence backgrounds on the cell images as either individuals or small clusters due to their stronger emission intensities and shorter lifetimes. These emission signals could also be precisely counted on single cell images. The count number may provide an approach for quantifying the target molecules in the cells.

  3. Fluorescent metal nanoshell probe to detect single miRNA in lung cancer cell.

    Science.gov (United States)

    Zhang, Jian; Fu, Yi; Mei, Yuping; Jiang, Feng; Lakowicz, Joseph R

    2010-06-01

    In this study, fluorescent metal nanoshells were synthesized as a molecular imaging agent to detect single microRNA (miRNA) molecules in the cells positive to lung cancer. These metal nanoshells were composed of silica spheres with encapsulated Ru(bpy)(3)(2+) complexes as cores and thin silver layers as shells. Compared with the silica spheres in the absence of metal, the metal nanoshells displayed an enhanced emission intensity, shortened lifetime, and extended photostability. The single-stranded probe oligonucleotides were covalently bound on the metal nanoshells to hybridize with the target miRNA-486 molecules in the cells. It was shown that with stronger emission intensity and longer lifetime, the conjugated metal nanoshells were isolated distinctly from the cellular autofluorescence on the cell images. These emission spots on the cell images were counted accurately and analyzed with a pool of cells representing the miRNA-486 expression levels in the cells. The results may reflect a genomic signal change and provide a reference to lung cancer early diagnosis as well as other diseases.

  4. Resonanant enhancement of molecular excitation intensity in inelastic electron scattering spectrum owing to interaction with plasmons in metallic nanoshell

    OpenAIRE

    Goliney, I. Yu.; Onykienko, Ye. V.

    2014-01-01

    A quantum-mechanical model to calculate the electron energy-loss spectra (EELS) for the system of a closely located metallic nanoshell and a molecule has been developed. At the resonance between the molecular excitation and plasmon modes in the nanoshell, which can be provided by a proper choice of the ratio of the inner and outer nanoshell radii, the cross-section of inelastic electron scattering at the molecular excitation energy is shown to grow significantly, because the molecular transit...

  5. Fabrication and infrared-transmission properties of monolayer hexagonal-close-packed metallic nanoshells

    Science.gov (United States)

    Chen, Jing; Xu, Rongqing; Liu, Zhengqi; Tang, Chaojun; Chen, Zhuo; Wang, Zhenlin

    2013-06-01

    This paper presents a novel method for fabricating a monolayer of hexagonal-close-packed metallic nanoshells with a small opening, based on a combination of a porous polymer template and a nanocrystal-seeded electroless plating technique. Light transmission spectra of the metallic nanoshell arrays are measured, which show that light can transmit through the dense particle assemblies via excitations of a variety of surface-plasmons (SPs). Further numerical simulations confirm these transmission resonances and reveal that they are attributed to the excitations of localized quadrupolar spherelike and Fano-type hybridized SP modes supported by the specific structure. The present metallic microstructure could find applications in plasmonics.

  6. Near-Infrared Super Resolution Imaging with Metallic Nanoshell Particle Chain Array

    CERN Document Server

    Kong, Weijie; Cao, Penfei; Cheng, Lin; Gong, Li; Zhao, Xining; Yang, Lili

    2012-01-01

    We propose a near-infrared super resolution imaging system without a lens or a mirror but with an array of metallic nanoshell particle chain. The imaging array can plasmonically transfer the near-field components of dipole sources in the incoherent and coherent manners and the super resolution images can be reconstructed in the output plane. By tunning the parameters of the metallic nanoshell particle, the plasmon resonance band of the isolate nanoshell particle red-shifts to the near-infrared region. The near-infrared super resolution images are obtained subsequently. We calculate the field intensity distribution at the different planes of imaging process using the finite element method and find that the array has super resolution imaging capability at near-infrared wavelengths. We also show that the image formation highly depends on the coherence of the dipole sources and the image-array distance.

  7. Surface nano-patterning in realizing large-scale ordered arrays of metallic nanoshells with controllable structures and properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shikuan; Xu, Feng; Winkler, Nina; Zhao, Huaping; Lei, Yong [Institute of Materials Physics, University of Muenster (Germany); Center for Nanotechnology (Germany)

    2011-07-01

    Surface patterns of metallic nanostructure arrays play an important role in many application areas such as surface-enhanced Raman scattering sensors, lithium-ion batteries, solar cells, and optical devices. Here we present an innovative surface nano-patterning technique in our group for realizing large-scale ordered arrays of metallic spherical nanoshells with well-defined structures. Silver nanoshell arrays are synthesized using polystyrene sphere templates by an electrophoretic process. The fabricated Ag nanoshell arrays have a high controllability of the structural parameters, including the diameter, the surface roughness, and the inter-shell spacing. And the properties of the synthesized nanoshell arrays can be controlled based on the adjustment of the structural parameters. As an example, tunable surface-enhanced Raman scattering and localized surface plasmon resonance of the nanoshell arrays are demonstrated by controlling the structural parameters. The presented surface nano-patterning technique is a general fabrication process in achieving not only metallic nanoshell arrays, but also nanoshell arrays of other materials, such as semiconductors and metallic oxides.

  8. Resonanant enhancement of molecular excitation intensity in inelastic electron scattering spectrum owing to interaction with plasmons in metallic nanoshell

    CERN Document Server

    Goliney, I Yu

    2014-01-01

    A quantum-mechanical model to calculate the electron energy-loss spectra (EELS) for the system of a closely located metallic nanoshell and a molecule has been developed. At the resonance between the molecular excitation and plasmon modes in the nanoshell, which can be provided by a proper choice of the ratio of the inner and outer nanoshell radii, the cross-section of inelastic electron scattering at the molecular excitation energy is shown to grow significantly, because the molecular transition borrows the oscillator strength from a plasmon. The enhancement of the inelastic electron scattering by the molecule makes it possible to observe molecular transitions with an electron microscope. The dependences of the EEL spectra on the relative arrangement of the molecule and the nanoshell, the ratio between the inner and outer nanoshell radii, and the scattering angle are plotted and analyzed.

  9. Spiky gold nanoshells.

    Science.gov (United States)

    Sanchez-Gaytan, Brenda L; Park, So-Jung

    2010-12-21

    We report a high-yield synthetic method for a new type of metal nanostructure, spiky gold nanoshells, which combine the morphological characteristics of hollow metal nanoshells and nanorods. Our method utilizes block copolymer assemblies and polymer beads as templates for the growth of spiky nanoshells. Various shapes of spiky metal nanoshells were prepared in addition to spherical nanoshells by using block copolymer assemblies such as rod-like micelles, vesicles, and bilayers as templates. Furthermore, spiky gold shells encapsulating magnetic nanoparticles or quantum dots were prepared based on the ability of block copolymers to self-assemble with various types of nanoparticles and molecules. The capability to encapsulate other materials in the core, the shape tunability, and the highly structured surface of spiky nanoshells should benefit a range of imaging, sensing, and medical applications of metal nanostructures.

  10. Optical and spectral tunability of multilayer spherical and cylindrical nanoshells

    Science.gov (United States)

    Daneshfar, Nader; Bazyari, Khashayar

    2014-08-01

    This theoretical work presents a comparative study of the optical properties and spectral tunability of hybrid multilayer spherical and cylindrical nanoshells based on the quasi-static approximation of classical electrodynamics. The interband transitions have been considered using the Drude-Lorentz model for the complex dielectric function of metallic layers because the optical properties of metals arise from both the optical excitation of interband transitions and the free-electron response. A general formula for N-ayer concentric nanoshells is arranged, and numerical calculations are performed for the four-layer nanoshells as an example. We have analyzed in detail different configurations of nanoshells such as dielectric-metal-dielectric-metal with dielectric core, metal-dielectric-metal-dielectric with metal core and semiconductor-metal-dielectric-metal with semiconductor core because composition of nanoshells have dramatic influence on their optical properties. The absorbance spectrum behavior of the shell thicknesses, surrounding medium, shape and composition of each layer of the nanoshell is numerically investigated.

  11. Synthesis and optical properties of nanorattles and multiple-walled nanoshells/nanotubes made of metal alloys.

    Science.gov (United States)

    Sun, Yugang; Wiley, Benjamin; Li, Zhi-Yuan; Xia, Younan

    2004-08-04

    The galvanic replacement reaction between silver and chloroauric acid has been exploited as a powerful means for preparing metal nanostructures with hollow interiors. Here, the utility of this approach is further extended to produce complex core/shell nanostructures made of metals by combining the replacement reaction with electroless deposition of silver. We have fabricated nanorattles consisting of Au/Ag alloy cores and Au/Ag alloy shells by starting with Au/Ag alloy colloids as the initial template. We have also prepared multiple-walled nanoshells/nanotubes (or nanoscale Matrioshka) with a variety of shapes, compositions, and structures by controlling the morphology of the template and the precursor salt used in each step of the replacement reaction. There are a number of interesting optical features associated with these new core/shell metal nanostructures. For example, nanorattles made of Au/Ag alloys displayed two well-separated extinction peaks, a feature similar to that of gold or silver nanorods. The peak at approximately 510 nm could be attributed to the Au/Ag alloy cores, while the other peak was associated with the Au/Ag alloy shells and could be continuously tuned in the spectral range from red to near-infrared.

  12. 有序金属纳米壳材料%Ordered Metal Nanoshell Materials

    Institute of Scientific and Technical Information of China (English)

    饶艳英; 钱卫平

    2011-01-01

    Ordered metal nanostructures such as ordered hollow nanoshells and macroporous nanostructures have attracted great attentions because they have both metal and photonic crystal properties.In this review,we first introduce the methods and main processes of fabricating these metal structures.The fabrication processes mainly include the assembling of template,the deposition of metal shell and the removing of template.All these three processes are reviewed respectively.Furthermore,the ordered metal nanostructures possess unique properties due to their small size,low dimension,and interactions between neighboring units,which have been used as substrates of surface-enhanced Raman scattering(SERS),high efficiency catalyst,immunoassay and nanosensors,etc.Finally,the prospects of the ordered metal nanostructures along with the existed problems are presented.%有序金属纳米壳结构特别是有序中空纳米壳及大孔结构兼具了光子晶体和金属纳米壳结构的光学特性,引起了国内外学者的广泛关注。本文详细介绍了有序金属纳米壳材料的制备方法与步骤,主要包括胶体晶模板的组装、所需金属壳层的制备以及胶体晶模板的去除三步,并对各步的制备方法及特点进行了描述。此外,本文还对金属纳米壳有序材料的各种应用进行了综述,简要分析了目前存在的问题并展望了今后该材料的研究方向。

  13. Eigenmodes of coupled plasmons-excitons in a system of adjoining spherical metallic-J-aggregate nanoshells

    Science.gov (United States)

    Manassah, Jamal T.

    2013-08-01

    Using the spherical modes of the full-Maxwell equations, I compute the eigenfrequencies of the complex consisting of concentric passive inner core, a metallic nanoshell, molecular J-aggregate adsorped to the surface of the metal, immersed in a passive solution. The coupling of the plasmons of the metal to the excitons of the J-aggregate is incorporated in the formalism through the continuity conditions for the tangential components of the electric field and magnetic flux density at the materials interfaces. Comparison with results obtained using the electrostatic approximation shows deviations in both the values of the resonance frequencies and their decay-rates.

  14. Phenolic acid induced growth of gold nanoshells precursor composites and their application in antioxidant capacity assay.

    Science.gov (United States)

    Ma, Xiaoyuan; Qian, Weiping

    2010-11-15

    In the present work, the gold nanoshells (GNSs) precursor composites were preadsorbed onto the surface of ITO substrates. With the treatment of modified electrodes immersed in the gold nanoparticles (GNPs) growth solution containing different phenolic acids, the GNSs precursor composites were enlarged to varying degrees. Phenolic acids with one or more phenolic hydroxyl groups served as reductants for the growth of GNPs. The enlargement conditions varied with the different reducing capacity of phenolic acids, exhibiting specific morphologies differ from the complete GNSs. Consequently, the UV-vis-NIR spectra and cyclic voltammetry curves for the phenolic acid-treated ITO electrode were gradually changed. Results showed that the higher reducing capacity for phenolic acid to reduce AuCl(4)(-) to Au(0) resulted in the intensified localized surface plasmon resonance features and reduced cathodic currents. The spectral wavelength peaks red shifted hundreds of nanometers across the visible region. Moreover, the antioxidant capacity of phenolic acids correlates well with their reducing activity, both of which reflect their tendency to donate electrons. Thus, the optical and electrochemical results could be used to evaluate the antioxidant capacity of phenolic acids by utilizing GNSs precursor composites as nanoprobes. The method is simple, rapid and could be used in visual analysis to a certain extent.

  15. Bioinspired, cytocompatible mineralization of silica-titania composites: thermoprotective nanoshell formation for individual chlorella cells.

    Science.gov (United States)

    Ko, Eun Hyea; Yoon, Yeonjung; Park, Ji Hun; Yang, Sung Ho; Hong, Daewha; Lee, Kyung-Bok; Shon, Hyun Kyong; Lee, Tae Geol; Choi, Insung S

    2013-11-18

    Hard-shell case: Using a (RKK)4 D8 peptide allows mineralization to occur under cytocompatible conditions. Thus individual Chlorella cells could be encapsulated within a SiO2 -TiO2 nanoshell with high cell viability (87 %). The encapsulated Chlorella showed an almost threefold increase in their thermo-tolerance after 2 h at 45 °C.

  16. Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La.

    Science.gov (United States)

    Wei, Liqiu; Che, Ruxin; Jiang, Yijun; Yu, Bing

    2013-12-01

    Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve -24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.

  17. Modal interference in spiky nanoshells.

    Science.gov (United States)

    Hastings, Simon P; Qian, Zhaoxia; Swanglap, Pattanawit; Fang, Ying; Engheta, Nader; Park, So-Jung; Link, Stephan; Fakhraai, Zahra

    2015-05-04

    Near-field enhancement of the electric field by metallic nanostructures is important in non-linear optical applications such as surface enhanced Raman scattering. One approach to producing strong localization of the electric field is to couple a dark, non-radiating plasmonic mode with a broad dipolar resonator that is detectable in the far-field. However, characterizing or predicting the degree of the coupling between these modes for a complicated nanostructure can be quite challenging. Here we develop a robust method to solve the T-matrix, the matrix that predicts the scattered electric fields of the incident light, based on finite-difference time-domain (FDTD) simulations and least square fitting algorithms. This method allows us to simultaneously calculate the T-matrix for a broad spectral range. Using this method, the coupling between the electric dipole and quadrupole modes of spiky nanoshells is evaluated. It is shown that the built-in disorder in the structure of these nanoshells allows for coupling between the dipole modes of various orientations as well as coupling between the dipole and the quadrupole modes. A coupling strength of about 5% between these modes can explain the apparent interference features observed in the single particle scattering spectrum. This effect is experimentally verified by single particle backscattering measurements of spiky nanoshells. The modal interference in disordered spiky nanoshells can explain the origin of the spectrally broad quadrupole resonances that result in strong Quadrupole Enhanced Raman Scattering (QERS) in these nanoparticles.

  18. Preparation and microwave absorbing properties of the core-nanoshell composite absorbers with the magnetic fly-ash hollow cenosphere as core.

    Science.gov (United States)

    Che, Ruxin; Wang, Chunxia; Ni, Yingjuan; Yu, Bing

    2011-06-01

    Electromagnetic (EM) wave pollution has become the chief physical pollution for environment. The core-nanoshell composite absorbers with magnetic fly-ash hollow cenosphere as core and nanocrystalline magnetic material as shell were prepared by high-energy ball milling. The results of X-ray diffraction analysis (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and vector network analyzer (VNA) analysis indicated that perfect-crystalline nanomagnetic material coating was gotten with a particle size of 12 nm, being dried at 60°C for 2 hr and calcined at 400°C for 1 hr after ball milling. The exchange-coupling interaction happened between ferrite of cenosphere and soft magnet γ-Fe203 coating, it enhances magnetic loss of composite absorbers. In the frequency between 1 MHz and 1 GHz, the absorbing effectiveness of the core-nanoshell composite absorbers can achieve -30 dB, it is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.

  19. Metal matrix Composites

    Directory of Open Access Journals (Sweden)

    Pradeep K. Rohatgi

    1993-10-01

    Full Text Available This paper reviews the world wide upsurge in metal matrix composite research and development activities with particular emphasis on cast metal-matrix particulate composites. Extensive applications of cast aluminium alloy MMCs in day-to-day use in transportation as well as durable good industries are expected to advance rapidly in the next decade. The potential for extensive application of cast composites is very large in India, especially in the areas of transportation, energy and electromechanical machinery; the extensive use of composites can lead to large savings in materials and energy, and in several instances, reduce environmental pollution. It is important that engineering education and short-term courses be organized to bring MMCs to the attention of students and engineering industry leaders. India already has excellent infrastructure for development of composites, and has a long track record of world class research in cast metal matrix particulate composites. It is now necessary to catalyze prototype and regular production of selected composite components, and get them used in different sectors, especially railways, cars, trucks, buses, scooters and other electromechanical machinery. This will require suitable policies backed up by funding to bring together the first rate talent in cast composites which already exists in India, to form viable development groups followed by setting up of production plants involving the process engineering capability already available within the country. On the longer term, cast composites should be developed for use in energy generation equipment, electronic packaging aerospace systems, and smart structures.

  20. Fundamental research on the label-free detection of protein adsorption using near-infrared light-responsive plasmonic metal nanoshell arrays with controlled nanogap

    OpenAIRE

    Uchida, Shuhei; Zettsu, Nobuyuki; Endo, Katsuyoshi; Yamamura, Kazuya

    2013-01-01

    In this work, we focused on the label-free detection of simple protein binding using near-infrared light-responsive plasmonic nanoshell arrays with a controlled interparticle distance. The nanoshell arrays were fabricated by a combination of colloidal self-assembly and subsequent isotropic helium plasma etching under atmospheric pressure. The diameter, interparticle distance, and shape of nanoshells can be tuned with nanometric accuracy by changing the experimental conditions. The Au, Ag, and...

  1. Quasiparticle Gaps and Exciton Coulomb Energies in Si Nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Frey, K. [University of Illinois, Chicago; Idrobo Tapia, Juan C [ORNL; Tiago, Murilo L [ORNL; Reboredo, Fernando A [ORNL; Ogut, Serdar [University of Illinois, Chicago

    2009-01-01

    Quasiparticle gaps and exciton Coulomb energies of H-passivated spherical Si nanoshells are computed using rst principles SCF and GW methods. We nd that the quasiparticle gap of a nanoshell depends on both its inner radius R1 (weakly) and outer radius R2 (strongly). These dependences on R1 and R2 are mostly consistent with electrostatics of a metallic shell. We also nd that the unscreened Coulomb energy ECoul in Si nanoshells has a somewhat unexpected size dependence at xed outer radius R2: ECoul decreases as the nanoshell becomes more conning, contrary to what one would expect from quantum connement eects. We show that this is a consequence of an increase in the average electron-hole distance, giving rise to reduced exciton Coulomb energies in spite of the reduction in the conning nanoshell volume.

  2. Effect of number density on optimal design of gold nanoshells for plasmonic photothermal therapy.

    Science.gov (United States)

    Sikdar, Debabrata; Rukhlenko, Ivan D; Cheng, Wenlong; Premaratne, Malin

    2013-01-01

    Despite much research efforts being devoted to the design optimization of metallic nanoshells, no account is taken of the fact that the number of the nanoshells that can be delivered to a given cancerous site vary with their size. In this paper, we study the effect of the nanoshell number density on the absorption and scattering properties of a gold-nanoshell ensemble exposed to a broadband near-infrared radiation, and optimize the nanoshells' dimensions for efficient cancer treatment by analyzing a wide range of human tissues. We first consider the general situation in which the number of the delivered nanoshells decreases with their mean radius R as ∝ R(-β), and demonstrate that the optimal design of nanoshells required to treat cancer most efficiently depends critically on β. In the case of β = 2, the maximal energy absorbed (scattered) by the ensemble is achieved for the same dimensions that maximize the absorption (scattering) efficiency of a single nanoshell. We thoroughly study this special case by the example of gold nanoshells with silica core. To ensure that minimal thermal injury is caused to the healthy tissue surrounding a cancerous site, we estimate the optimal dimensions that minimize scattering by the nanoshells for a desired value of the absorption efficiency. The comparison of gold nanoshells with different cores shows that hollow nanoshells exhibiting relatively low absorption efficiency are less harmful to the healthy tissue and, hence, are preferred over the strongly absorbing nanoshells. For each of the cases analyzed, we provide approximate analytical expressions for the optimal nanoshell dimensions, which may be used as design guidelines by experimentalists, in order to optimize the synthesis of gold nanoshells for treating different types of human cancer at their various growth stages.

  3. Nanostructured metal-polyaniline composites

    Science.gov (United States)

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2010-08-31

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  4. Shedding light on the growth of gold nanoshells.

    Science.gov (United States)

    Sauerbeck, Christian; Haderlein, Michael; Schürer, Benedikt; Braunschweig, Björn; Peukert, Wolfgang; Klupp Taylor, Robin N

    2014-03-25

    Nanostructured particles containing noble metals can have highly tunable localized surface plasmon resonances and are therefore of particular interest for numerous applications. Nanoshells comprising a dielectric core and gold or silver shell are a widely researched systems because of the strong dependence of their optical properties on the ratio of core diameter to shell thickness. Although seeded-growth procedures have been developed to produce these particles, the many reported studies show significant variation in the nanoshell morphologies and hence optical properties. In order to establish processes that reproducibly synthesize nanoshells with high optical quality, it is necessary to develop techniques that monitor changes at the core particle surface during shell growth. For that purpose, we have carried out in situ nonlinear second-harmonic scattering (SHS) and linear vis-NIR extinction spectroscopy simultaneously during the seeded growth of gold nanoshells on silica core particles. Our SHS measurements show a striking variation in the nonlinear optical properties of the growing gold nanoshells. In comparison with linear optical measurements and with scanning electron microscopy (SEM) images made of gold nanoshells produced with varying shell completenesses, the SHS signal was observed to reach a peak intensity at a stage prior to shell closure. We attribute this high sensitivity of the SHS signal to the incomplete nanoshell surface morphology to the generation and subsequent degeneration of regions of electric field enhancement at gaps between isolated gold islands, which grow and coalesce. This conclusion is corroborated by finite-difference time-domain simulations of incomplete nanoshells. We suggest that the in situ analytical approach demonstrated here offers significant promise for future activities regarding the in-process optimization of the morphology and optical properties of metal nanoshells and other nanostructured plasmonic particles.

  5. Metal Nanoparticle Aerogel Composites

    Science.gov (United States)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  6. Ultrafast electron dynamics in gold nanoshells

    Science.gov (United States)

    Westcott, Sarah Linda

    2001-10-01

    In metallic nanostructures, the interaction of excited electrons with the nanostructure surface may result in electron relaxation dynamics that are significantly different than those predicted by electron-lattice coupling. These ultrafast electron dynamics were monitored by pump-probe measurements of the time-resolved change in transmission. Using femtosecond pulses from a cavity-dumped titanium-doped sapphire laser, two types of nanoparticles with a core-shell geometry were studied. Nanoshells are nanoparticles with a dielectric core surrounded by a continuous thin metal shell. For nanoshells, the plasmon resonance wavelength is tunable by changing the core and shell dimensions. For nanoshells with a gold sulfide core and a gold shell, two conditions were observed under which electron relaxation was different than predicted by electron-phonon coupling. First, electron relaxation occurred more rapidly for gold-gold sulfide nanoshells embedded in polymer films than for nanoshells dispersed in water, with lifetimes of 1.6 ps and 3 to 5 ps, respectively. Second, for nanoshells dispersed in water, the electron relaxation lifetime decreased with adsorption of p-aminobenzoic acid (to 1.7 ps) or aniline (to 1.9 ps) on the nanoshells. With adsorbed n-propylamine or p-mercaptobenzoic acid, electron relaxation transpired in 2.8 ps or 2.4 ps, respectively. Density functional theory calculations indicated that the molecules leading to the fastest electron relaxation possessed the largest induced dipole moments near a metal surface. Semicontinuous gold films grown around a silica nanoparticle core exhibited spectral and dynamical optical signatures of the percolation threshold. Compared to continuous shells, the electron dynamics in the semicontinuous shell layer were dramatically different as additional induced bleaching was observed in the first 500 fs. The observed dynamics are consistent with a rate equation model in which the electrons are initially excited in localized

  7. Plasmonic-enhanced two-photon fluorescence with single gold nanoshell

    Science.gov (United States)

    Zhang, TianYue; Lu, GuoWei; Shen, HongMing; Perriat, P.; Martini, M.; Tillement, O.; Gong, QiHuang

    2014-06-01

    Single gold nanoshell with mutilpolar plasmon resonances is proposed to enhance two-photon fluorescence efficiently. The single emitter single nanoshell configuration is studied systematically by employing the finite-difference time-domain method. The emitter located inside or outside the nanoshell at various positions leads to a significantly different enhancement effect. The fluorescent emitter placed outside the nanoshell can achieve large fluorescence intensity given that both the position and orientation of the emission dipole are optimally controlled. In contrast, for the case of the emitter placed inside the nanoshell, it can experience substantial two-photon fluorescence enhancement without strict requirements upon the position and dipole orientations. Metallic nanoshell encapsulating many fluorescent emitters should be a promising nanocomposite configuration for bright two-photon fluorescence label. The results provide a comprehensive understanding about the plasmonic-enhanced two-photon fluorescence behaviors, and the nanocomposite configuration has great potential for optical detecting, imaging and sensing in biological applications.

  8. Machining of Metal Matrix Composites

    CERN Document Server

    2012-01-01

    Machining of Metal Matrix Composites provides the fundamentals and recent advances in the study of machining of metal matrix composites (MMCs). Each chapter is written by an international expert in this important field of research. Machining of Metal Matrix Composites gives the reader information on machining of MMCs with a special emphasis on aluminium matrix composites. Chapter 1 provides the mechanics and modelling of chip formation for traditional machining processes. Chapter 2 is dedicated to surface integrity when machining MMCs. Chapter 3 describes the machinability aspects of MMCs. Chapter 4 contains information on traditional machining processes and Chapter 5 is dedicated to the grinding of MMCs. Chapter 6 describes the dry cutting of MMCs with SiC particulate reinforcement. Finally, Chapter 7 is dedicated to computational methods and optimization in the machining of MMCs. Machining of Metal Matrix Composites can serve as a useful reference for academics, manufacturing and materials researchers, manu...

  9. Composite and Nanocomposite Metal Foams

    Directory of Open Access Journals (Sweden)

    Isabel Duarte

    2016-01-01

    Full Text Available Open-cell and closed-cell metal foams have been reinforced with different kinds of micro- and nano-sized reinforcements to enhance their mechanical properties of the metallic matrix. The idea behind this is that the reinforcement will strengthen the matrix of the cell edges and cell walls and provide high strength and stiffness. This manuscript provides an updated overview of the different manufacturing processes of composite and nanocomposite metal foams.

  10. Metal Matrix Composite Solar Cell Metallization

    Directory of Open Access Journals (Sweden)

    Wilt David M.

    2017-01-01

    Full Text Available Advanced solar cells are moving to ever thinner formats in order to save mass and in some cases improve performance. As cells are thinned, the possibility that they may fracture or cleave due to mechanical stresses is increased. Fractures of the cell can degrade the overall device performance if the fracture propagates through the contact metallization, which frequently occurs. To address this problem, a novel semiconductor metallization system based on multi-walled carbon nanotube (CNT reinforcement, termed metal matrix composite (MMC metallization is under investigation. Electro-mechanical characterization of MMC films demonstrate their ability to provide electrical conductivity over >40 micron wide cracks in the underlying semiconductor, with the carbon nanotubes bridging the gap. In addition, these materials show a “self-healing” behaviour, electrically reconnecting at ~30 microns when strained past failure. Triple junction (TJ space cells with MMC metallization demonstrated no loss in Jsc after intentional fracture, whereas TJ cells with conventional metallization suffer up to 50% Jsc loss.

  11. Nanoshell Encapsulated Li-ion Battery Anodes for Long Cycle Life Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new high capacity rechargeable Li battery anode based on Li metal alloys protected by carbon nanoshells will be developed. A reversible Li-ion capacity exceeding...

  12. Nanoshell-mediated robust entanglement between coupled quantum dots

    Science.gov (United States)

    Hakami, Jabir; Zubairy, M. Suhail

    2016-02-01

    The exact entanglement dynamics in a hybrid structure consisting of two quantum dots (QDs) in the proximity of a metal nanoshell is investigated. Nanoshells can enhance the local density of states, leading to a strong-coupling regime where the excitation energy can coherently be transferred between the QDs and the nanoshell in the form of Rabi oscillations. The long-lived entangled states can be created deterministically by optimizing the shell thickness as well as the ratio of the distances between the QDs and the surface of the shell. The loss of the system is greatly reduced even when the QDs are ultraclose to the shell, which signifies a slow decay rate of the coherence information and longtime entanglement preservation. Our protocol allows for an on-demand, fast, and almost perfect entanglement even at strong carrier-phonon interaction where other systems fail.

  13. Synthesis of palladium nanoshell using a layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Ashayer, Roya [Kings College London, Department of Mechanical Engineering (United Kingdom); Green, Mark [Kings College London, Department of Physics (United Kingdom); Mannan, Samjid H., E-mail: samjid.mannan@kcl.ac.u [Kings College London, Department of Mechanical Engineering (United Kingdom)

    2010-05-15

    Complete palladium nanoshells were prepared by reducing palladium ions in a one-step reaction onto preformed silica cores of ca. 90 nm, which had been coated with successive layers of poly(diallyldimethyl ammonium chloride), poly(sodium styrenesulfonate) and finally poly(diallyldimethyl ammonium chloride) to reverse the zeta potential of the silica cores. This constitutes the first reported method for complete palladium nanoshell formation without the use of other metals as nucleation sites. The morphology of the nanoshell is of the rough discrete particle type rather than the smooth continuous type.

  14. Composite pipe to metal joint

    Energy Technology Data Exchange (ETDEWEB)

    Leslie, James C.; Leslie, II, James C.; Heard, James; Truong, Liem V.; Josephson, Marvin

    2017-06-27

    A method for making a metal to composite tube joint including selecting an elongated interior fitting constructed with an exterior barrel, reduced in exterior diameter to form a distally facing annular shoulder and then projecting still further distally to form an interior sleeve having a radially outwardly facing bonding surface. Selecting an elongated metal outer sleeve formed proximally with a collar constructed for receipt over the barrel and increased in interior diameter and projecting distally to form an exterior sleeve having a radially inwardly facing bonding surface cooperating with the first bonding surface to form an annulus receiving an extremity of a composite tube and a bond bonding the extremity of the tube to the bonding surfaces.

  15. Triple plasmon resonance of bimetal nanoshell

    Energy Technology Data Exchange (ETDEWEB)

    Shirzaditabar, Farzad [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Saliminasab, Maryam, E-mail: m.saliminasab@yahoo.com [Young Researchers Club, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Arghavani Nia, Borhan [Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of)

    2014-07-15

    In this paper, light absorption spectra properties of a bimetal multilayer nanoshell based on quasi-static approach are investigated. Comparing with silver-dielectric-silver and silver-dielectric-gold nanoshells, gold-dielectric-silver nanoshells have three intense and separated plasmon peaks which are more suitable for multiplex biosensing. Calculations show that relatively small thickness of outer silver shell and large dielectric constant of middle dielectric layer of gold-dielectric-silver nanoshell are suitable to obtain the triple plasmon resonance.

  16. Triple plasmon resonance of bimetal nanoshell

    Science.gov (United States)

    Shirzaditabar, Farzad; Saliminasab, Maryam; Arghavani Nia, Borhan

    2014-07-01

    In this paper, light absorption spectra properties of a bimetal multilayer nanoshell based on quasi-static approach are investigated. Comparing with silver-dielectric-silver and silver-dielectric-gold nanoshells, gold-dielectric-silver nanoshells have three intense and separated plasmon peaks which are more suitable for multiplex biosensing. Calculations show that relatively small thickness of outer silver shell and large dielectric constant of middle dielectric layer of gold-dielectric-silver nanoshell are suitable to obtain the triple plasmon resonance.

  17. Optimizing Misch-Metal Compositions In Metal Hydride Anodes

    Science.gov (United States)

    Bugga, Ratnakumar V.; Halpert, Gerald

    1995-01-01

    Electrochemical cells based on metal hydride anodes investigated experimentally in effort to find anode compositions maximizing charge/discharge-cycle performances. Experimental anodes contained misch metal alloyed with various proportions of Ni, Co, Mn, and Al, and experiments directed toward optimization of composition of misch metal.

  18. Low-temperature dynamics of magnetic nanoshells

    KAUST Repository

    Zhang, Bei

    2010-09-01

    Well and poorly crystallized iron oxide nanoshells (or hollow nanoparticles) were successfully fabricated using the Kirkendall effect in an oxygen and in an air environment using Fe nanoparticles. The low-field, zero-field-cooling (ZFC) and field-cooling (FC), measurements on these two samples indicated that the inter-particle interactions between the well-crystallized nanoshells were much stronger than those in the poorly crystallized nanoshell assembly. However, the memory experiments showed that there was no spin-glass phase in the well-crystallized nanoshell assembly, whereas the signature of the spin-glass phase (or the memory effect) was evident in the poorly crystallized nanoshell assembly. This result suggests that the origin of the spin-glass characteristic observed in the poorly crystallized nanoshells is the existence of the spinglass phase within those particular nanoshells. Copyright © EPLA, 2010.

  19. Material parameter identification on metal matrix composites

    CSIR Research Space (South Africa)

    Jansen van Rensburg, GJ

    2012-07-01

    Full Text Available Tests were done on the compressive behaviour of different metal matrix composite materials. These extremely hard engineering materials consist of ceramic particles embedded in a metal alloy binder. Due to the high stiffness and brittle nature...

  20. Numerical analysis of surface plasmon resonance effects on a rotational silver nanorod/nanoshell dimer

    Science.gov (United States)

    Chou Chau, Yuan-Fong

    2013-06-01

    In this work, we numerically investigate the surface plasmon resonance (SPR) effects on a pair of rotational silver nanorod/nanoshell dimer with a finite height of 1000 nm by means of finite element method with three dimensional calculation. The rotational angles of the silver nanorod/nanoshell dimer are chosen θ=0°, θ=25°, θ=45° and θ=90°, respectively. The proposed structure exhibits a red-shifted localized SPR that can tuned over an extended wavelength range by varying the dielectric constant in metal nanoshell and the rotational angle of the silver nanorod/nanoshell dimer. The tunable optical properties on SPR phenomena are attributed to the rotational effect and a larger effective size of dielectric constant that is filled with a higher refractive medium of finite height of metal nanorod/nanoshell. This unique property of a pair of rotational nanorod/nanoshell dimer is highly attractive for serving as resonant center to hold and probe smaller nanostructures, such as biomolecules or quantum dots. Such structures also show significant promise for applications in nano-switch devices, sensing, and surface-enhanced spectroscopy, due to their strong and tunable plasmon resonances.

  1. In situ growth of hollow gold-silver nanoshells within porous silica offers tunable plasmonic extinctions and enhanced colloidal stability.

    Science.gov (United States)

    Li, Chien-Hung; Jamison, Andrew C; Rittikulsittichai, Supparesk; Lee, Tai-Chou; Lee, T Randall

    2014-11-26

    Porous silica-coated hollow gold-silver nanoshells were successfully synthesized utilizing a procedure where the porous silica shell was produced prior to the transformation of the metallic core, providing enhanced control over the structure/composition of the bimetallic hollow core. By varying the reaction time and the precise amount of gold salt solution added to a porous silica-coated silver-core template solution, composite nanoparticles were tailored to reveal a readily tunable surface plasmon resonance that could be centered across the visible and near-IR spectral regions (∼445-800 nm). Characterization by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that the synthetic methodology afforded particles having uniform composition, size, and shape. The optical properties were evaluated by absorption/extinction spectroscopy. The stability of colloidal solutions of our composite nanoparticles as a function of pH was also investigated, revealing that the nanoshells remain intact over a wide range of conditions (i.e., pH 2-10). The facile tunability, enhanced stability, and relatively small diameter of these composite particles (∼110 nm) makes them promising candidates for use in tumor ablation or as photothermal drug-delivery agents.

  2. Nanoshell-enabled photothermal cancer therapy: impending clinical impact.

    Science.gov (United States)

    Lal, Surbhi; Clare, Susan E; Halas, Naomi J

    2008-12-01

    Much of the current excitement surrounding nanoscience is directly connected to the promise of new nanoscale applications in cancer diagnostics and therapy. Because of their strongly resonant light-absorbing and light-scattering properties that depend on shape, noble metal nanoparticles provide a new and powerful tool for innovative light-based approaches. Nanoshellsspherical, dielectric core, gold shell nanoparticleshave been central to the development of photothermal cancer therapy and diagnostics for the past several years. By manipulating nanoparticle shape, researchers can tune the optical resonance of nanoshells to any wavelength of interest. At wavelengths just beyond the visible spectrum in the near-infrared, blood and tissue are maximally transmissive. When nanoshell resonances are tuned to this region of the spectrum, they become useful contrast agents in the diagnostic imaging of tumors. When illuminated, they can serve as nanoscale heat sources, photothermally inducing cell death and tumor remission. As nanoshell-based diagnostics and therapeutics move from laboratory studies to clinical trials, this Account examines the highly promising achievements of this approach in the context of the challenges of this complex disease. More broadly, these materials present a concrete example of a highly promising application of nanochemistry to a biomedical problem. We describe the properties of nanoshells that are relevant to their preparation and use in cancer diagnostics and therapy. Specific surface chemistries are necessary for passive uptake of nanoshells into tumors and for targeting specific cell types by bioconjugate strategies. We also describe the photothermal temperature increases that can be achieved in surrogate structures known as tissue phantoms and the accuracy of models of this effect using heat transport analysis. Nanoshell-based photothermal therapy in several animal models of human tumors have produced highly promising results, and we include

  3. Graphene composites containing chemically bonded metal oxides

    Indian Academy of Sciences (India)

    K Pramoda; S Suresh; H S S Ramakrishna Matte; A Govindaraj

    2013-08-01

    Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force microscopy and other techniques. Magnetite particles chemically bonded to graphene dispersible in various solvents have been prepared and they exhibit fairly high magnetization.

  4. Nanoshells for photothermal cancer therapy.

    Science.gov (United States)

    Morton, Jennifer G; Day, Emily S; Halas, Naomi J; West, Jennifer L

    2010-01-01

    Cancer is a leading cause of death in the United States and contributes to yearly rising health care costs. Current methods of treating cancer involve surgical removal of easily accessible tumors, radiation therapy, and chemotherapy. These methods do not always result in full treatment of the cancer and can in many cases damage healthy cells both surrounding the tissue area and systemically. Nanoshells are optically tunable core/shell nanoparticles that can be fabricated to strongly absorb in the near-infrared (NIR) region where light transmits deeply into tissue. When injected systemically, these particles have been shown to accumulate in the tumor due to the enhanced permeability and retention (EPR) effect and induce photothermal ablation of the tumor when irradiated with an NIR laser. Tumor specificity can be increased via functionalizing the nanoshell surface with tumor-targeting moieties. Nanoshells can also be made to strongly scatter light and therefore can be used in various imaging modalities such as dark-field microscopy and optical coherence tomography (OCT).

  5. Spectroscopic properties of a two-level atom interacting with a complex spherical nanoshell

    CERN Document Server

    Moroz, A

    2004-01-01

    Frequency shifts, radiative decay rates, the Ohmic loss contribution to the nonradiative decay rates, fluorescence yields, and photobleaching of a two-level atom radiating anywhere inside or outside a complex spherical nanoshell, i.e. a stratified sphere consisting of alternating silica and gold concentric spherical shells, are studied. The changes in the spectroscopic properties of an atom interacting with complex nanoshells are significantly enhanced, often more than two orders of magnitude, compared to the same atom interacting with a homogeneous dielectric sphere. The changes strongly depend on the nanoshell parameters and the atom position. When an atom approaches a metal shell,the radiative decay rates are strongly enhanced and they increase faster than the Ohmic loss contribution to the nonradiative decay rates. However, the majority of the emitted radiation does not escape to spatial infinity but instead is absorbed. The enhancement of the radiative decay rates in a close proximity of metal boundaries...

  6. Carbide-reinforced metal matrix composite by direct metal deposition

    Science.gov (United States)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  7. CARBON-CONTAINING COMPOSITES BASED ON METALS

    Directory of Open Access Journals (Sweden)

    VAGANOV V. E.

    2015-10-01

    Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

  8. Shielding performance of metal fiber composites

    Institute of Scientific and Technical Information of China (English)

    CHEN Gang; WU Bin; CHEN Ze-fei

    2004-01-01

    Metal fibers have been applied to construct composites with desirable electromagnetic interference shiel ding effectiveness and mechanical properties. Copper and stainless steel fibers were prepared with micro-saw fiberpulling combined cutting method. The cross section of the fibers is hook-like, which is beneficial to the improvement of bonding strength. Cement-based composites with copper and stainless steel fibers were fabricated and their electromagnetic shielding effectiveness was measured in the frequency range of 1 - 5 GHz. The results show that the electromagnetic interference shielding effectiveness of those composites is enhanced by the addition of metal fibers,which functions mainly due to the absorption. At some frequencies, 20 dB or more difference is obtained between the materials with and without metal fibers.

  9. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  10. Influence of structural defects on the optical properties of strongly coupled Au nanoshell arrays

    Science.gov (United States)

    Zhou, Xin; Fang, JianShu; Liao, XiangPing; Zhu, QianQuan; Liu, ZhiMin; Tang, Bin

    2013-09-01

    The effects of different defects on optical properties and plasmon resonances properties of Au nanoshell arrays were investigated by using the finite-difference time-domain (FDTD) theory. It is found that the optical properties of the nanoshell arrays are strongly influenced by different defects. We show that when the hollow Au nanoshell arrays are placed in air, there is a wide photonic band gap (PBG) in the infrared region, but the band gap becomes narrower as we introduced different defects. Based on the distributions of electric field component E z and the total energy distribution of the electric and the magnetic field, we show that there exhibit dipoles field distributions for the plasmon mode at the long-wavelength edge of the band gap, but composite higher order modes are excited at the short-wavelength edge of the band gap. The plasmon resonant modes also can be controlled by introducing defects.

  11. Preparation of Silver Nanoshells on Silica Particles by a Simple Two-step Process

    Institute of Scientific and Technical Information of China (English)

    Yu ZHANG; Ming MA; Ning GU; Ling XU; Kun Ji CHEN

    2004-01-01

    A simple two-step method was developed to prepare silver nanoshells coated on silica paticles.The method involves two steps: concentration of reaction precursor (AgNO3) on particle surfaces and subsequent reduction by formaldehyde.The obtained composite particles were characterized by TEM, ED, and SEM-EDS measurements.The results show that the silver nanoshell is coated on silica particle surface in the form of a polycrystalline (cubic structure) layer with average thickness of 20 nm and weight percentage of 19%.

  12. Magnetically mediated vortexlike assembly of gold nanoshells.

    Science.gov (United States)

    Sun, Jianfei; Dong, Jian; Sun, Dongke; Guo, Zhirui; Gu, Ning

    2012-04-24

    Gold nanoshells currently attract increasing research interests due to the important role in many subjects. For practical applications, random arrangement of the nanoparticles is often unfavored so that the assembly of gold nanoshells is becoming a central issue. We here proposed to utilize time-variant magnetic field to direct the assembly of gold nanoshells. It was discovered that the alternating magnetic field can mediate the vortex-like assembly of gold nanoshells. The mechanism was explored and thought to be relative with the electric field of induction which caused the thermal gradient on the substrate and the electric force. The vortexlike structure as well as the assembly mechanism will play an important role in research and application of gold nanomaterials.

  13. Self-Healing Metals and Metal Matrix Composites

    Science.gov (United States)

    Ferguson, J. B.; Schultz, Benjamin F.; Rohatgi, Pradeep K.

    2014-06-01

    Self-healing in inorganic materials is a relatively new area in materials science and engineering that draws inspiration from biological systems that can self-repair damage. This article reviews the preliminary attempts to impart self-healing behavior to metals. Several challenges yet exist in the development of metallic alloys that can self-repair damage, including surface bonding issues, such as liquid/solid contact angle (wetting) and oxidation, and practical issues, such as capillary pressure for delivery of a liquid metal to a damaged area or crack, and the overall mechanical properties of a composite system. Although the applied research approaches reviewed have obtained marginal success, the development of self-healing metallic systems has the potential to benefit a wide range of industrial applications and thus deserves greater investment in fundamental research.

  14. Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

    Science.gov (United States)

    Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

    2009-01-01

    A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

  15. High temperature metal and ceramic composites

    Science.gov (United States)

    Signorelli, R. A.; Dicarlo, J. A.

    1985-01-01

    The Materials Division at NASA Lewis is engaged in research and development efforts on behalf of fiber-reinforced composite materials that are lighter, stiffer, and more structurally reliable than conventional monolithic alloys and ceramics in applications that range from the cryogenic to the refractory. Attention is presently given to metal matrix composites, in which high performance depends on stiff, strong and thermally stable large diameter fibers, with chemically stable interfacial bonding and good coefficient of thermal expansion matching between fibers and matrices, and to ceramic matrix composites, in which intermediate strength interfacial bonds must allow cracks to propagate through the matrix only, while retaining good load transfer characteristics between fiber and matrix.

  16. Preparation and characterization of polymeric thin films containing gold nanoshells via electrostatic layer-by-layer self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Ho; Jamison, Andrew C.; Hoffman, David M., E-mail: hoffman@uh.edu; Jacobson, Allan J., E-mail: ajjacob@uh.edu; Lee, T. Randall, E-mail: trlee@uh.edu

    2014-05-02

    As an initial step in the development of surfaces for collecting thermal energy, gold shell/silica core particles (∼ 200 nm in diameter with shells ∼ 25 nm thick) were synthesized and incorporated into organic polymeric thin films. The morphologies of these nanoshells were characterized with scanning and transmission electron microscopy. Powder X-ray diffraction demonstrated that the gold layers were highly crystalline. Thin films containing the gold nanoshells and polyethyleneimine were generated using dip-coating techniques based on electrostatic layer-by-layer self-assembly methods. Scanning electron microscopy was used to image the resultant composite films, which contained uniformly distributed gold nanoshells with limited aggregation. The optical properties were analyzed by absorption spectroscopy, revealing broad extinctions ranging from the visible to the near-IR spectral regions. X-ray photoelectron spectroscopy spectra were also obtained to determine the elements present and the oxidation states of these elements. - Highlights: • Prepared gold nanoshells with broad light absorption from visible to near IR. • Added the gold nanoshells to polyethyleneimine films via layer-by-layer assembly. • The resulting layered thin films exhibited minimal gold nanoshell aggregation.

  17. Metallic and intermetallic-bonded ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  18. Cancer theranostics with gold nanoshells.

    Science.gov (United States)

    Zhao, Jun; Wallace, Michael; Melancon, Marites P

    2014-09-01

    Gold nanoshells (AuNSs) present a vivid example of integrating nanoscience in order to solve a biomedical problem. AuNSs exhibit tunable surface plasmon resonance, which can be tuned to the near-infrared region in order to realize optimal tissue penetration. The highly efficient light-to-heat transformation by AuNSs during laser irradiation causes thermal damage to the tumor without damaging healthy organs. Transient nanobubbles can form around AuNSs during laser treatment and induce mechanical stress specifically in tumor cells. AuNSs also serve as a versatile platform for the delivery of various diagnostic and therapeutic agents. In this article, we describe the physicochemical properties of AuNSs in the context of their design, preparation and application in cancer theranostics. Ultimately, we look beyond the current research on AuNSs and discussed future challenges to their successful translation into clinical use.

  19. Colloidal forming of metal/ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Herencia, A.J.; Gutierrez, C.A.; Millan, A.J.; Nieto, M.I.; Moreno, R. [Inst. de Ceramica y Vidrio, Madrid (Spain)

    2002-07-01

    Metal/Ceramic composites have very attractive properties as either structural or electronic materials. For certain applications, complex microstructures and shapes are required. Colloidal processing of ceramics has proved to provide better properties and allows to obtain near net complex shaped parts. However colloidal processing has not received a similar attention in powder metallurgy. This work deals with the colloidal approach to the forming of metallic and metal/ceramic composites in an aqueous medium. Rheological behavior of concentrated pure nickel, nickel/alumina and nickel/zirconia suspensions is studied and optimized for obtaining flat surfaces or near net shaped parts by tape casting and gel casting respectively. In each case the influence of the processing additives (acrylic binders for tape casting and carrageenans for gel casting) on the rheological behavior of the slurries is determined. Pure nickel and nickel/ceramic composites with different compositions have been prepared. Static and dynamic sintering studies were performed at different conditions in order to control the porosity and microstructure of the final bodies, which were characterized by optical microscopy. (orig.)

  20. Metal-polymer composites comprising nanostructures and applications thereof

    Science.gov (United States)

    Wang, Hsing-Lin; Jeon, Sea Ho; Mack, Nathan H.

    2011-08-02

    Metal-polymer composites, and methods of making and use thereof, said composites comprising a thermally-cured dense polyaniline substrate; an acid dopant; and, metal nanostructure deposits wherein the deposits have a morphology dependent upon the acid dopant.

  1. Corrosion Protection of Metal Matrix Composites

    Science.gov (United States)

    1990-04-01

    2, 162 (1986). 8. B. R. W. Hinton, D. R. Arnott, and N. E. Ryan, Metals Forum, Z, 211,(1984) 9. Ullmann , Fritz, "Ullmann’s Encyclopedia of Industrial ... Chemistry ", (1985). 10. F. Keller, M. S . Hunter, and 0. L. Robinson, J. Electrochem Soc., IM0, 411 0 (1953) 11. F. Mansfeld, S . Lin, S . Kim, and H...OIC FILE COPY "/9° * AD-A222 951 CORROSION PROTECTION OF METAL MATRIX COMPOSITES 0 FINAL REPORT F. MANSFELD, S . LIN AND H. SHIN APRIL 1990 0 U. S

  2. Metal nanowire-graphene composite transparent electrodes

    Science.gov (United States)

    Mankowski, Trent; Zhu, Zhaozhao; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine; Mansuripur, Masud; Falco, Charlies M.

    2014-10-01

    Silver nanowires with 40 nm diameter and copper nanowires with 150 nm diameter were synthesized using low-temperature routes, and deposited in combination with ultrathin graphene sheets for use as transparent conductors. A systematic and detailed analysis involving nature of capping agent for the metal nanowires, annealing of deposited films, and pre-treatment of substrates revealed critical conditions necessary for preparing high performance transparent conducting electrodes. The best electrodes show ~90% optical transmissivity and sheet resistance of ~10 Ω/□, already comparable to the best available transparent electrodes. The metal nanowire-graphene composite electrodes are therefore well suited for fabrication of opto-electronic and electronic devices.

  3. Biomimetic Composite-Metal Hip Resurfacing Implant

    Directory of Open Access Journals (Sweden)

    Habiba Bougherara

    2008-01-01

    Full Text Available Hip resurfacing technique is a conservative arthroplasty used in the young patient in which the femoral head is reshaped to accept metal cap with small guide stem. In the present investigation, a hybrid composite-metal resurfacing implant is proposed. The cup is made of carbon fiber/polyamide 12 (CF/PA12 covered with a thin layer of cobalt chrome (Co-Cr. Finite element (FE method was applied to analyze and compare the biomechanical performances of the hybrid hip resurfacing (HHR and the conventional Birmingham (BHR. Results of the finite element analysis showed that the composite implant leads to an increase in stresses in the cancellous bone by more than 15% than BHR, indicating a lower potential for stress shielding and bone fracture and higher potential for bone apposition with the HHR.

  4. Spin Forming of Aluminum Metal Matrix Composites

    Science.gov (United States)

    Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    An exploratory effort between NASA-Marshall Space Flight Center (MSFC) and SpinCraft, Inc., to experimentally spin form cylinders and concentric parts from small and thin sheets of aluminum Metal Matrix Composites (MMC), successfully yielded good microstructure data and forming parameters. MSFC and SpinCraft will collaborate on the recent technical findings and develop strategy to implement this technology for NASA's advanced propulsion and airframe applications such as pressure bulkheads, combustion liner assemblies, propellant tank domes, and nose cone assemblies.

  5. Nanostructured metal-polyaniline composites and applications thereof

    Science.gov (United States)

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2012-10-02

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  6. Liquid Metal Infiltration Processing of Metallic Composites: A Critical Review

    Science.gov (United States)

    Sree Manu, K. M.; Ajay Raag, L.; Rajan, T. P. D.; Gupta, Manoj; Pai, B. C.

    2016-10-01

    Metal matrix composites (MMC) are one of the advanced materials widely used for aerospace, automotive, defense, and general engineering applications. MMC can be tailored to have superior properties such as enhanced high-temperature performance, high specific strength and stiffness, increased wear resistance, better thermal and mechanical fatigue, and creep resistance than those of unreinforced alloys. To fabricate such composites with ideal properties, the processing technique has to ensure high volume fraction of reinforcement incorporation, uniform distribution of the reinforcement, and acceptable adhesion between the matrix and the reinforcing phase without unwanted interfacial reactions which degrades the mechanical properties. A number of processing techniques such as stir casting/vortex method, powder metallurgy, infiltration, casting etc. have been developed to synthesize MMC employing a variety of alloy and the reinforcement's combinations. Among these, infiltration process is widely used for making MMC with high volume fraction of reinforcements and offers many more advantages compared to other conventional manufacturing processes. The present paper critically reviews the various infiltration techniques used for making the MMC, their process parameters, characteristics, and selected studies carried out worldwide and by authors on the development of metal ceramic composites by squeeze infiltration process.

  7. The Robust Assembly of Small Symmetric Nanoshells.

    Science.gov (United States)

    Wagner, Jef; Zandi, Roya

    2015-09-01

    Highly symmetric nanoshells are found in many biological systems, such as clathrin cages and viral shells. Many studies have shown that symmetric shells appear in nature as a result of the free-energy minimization of a generic interaction between their constituent subunits. We examine the physical basis for the formation of symmetric shells, and by using a minimal model, demonstrate that these structures can readily grow from the irreversible addition of identical subunits. Our model of nanoshell assembly shows that the spontaneous curvature regulates the size of the shell while the mechanical properties of the subunit determine the symmetry of the assembled structure. Understanding the minimum requirements for the formation of closed nanoshells is a necessary step toward engineering of nanocontainers, which will have far-reaching impact in both material science and medicine.

  8. Composite Metal-hydrogen Electrodes for Metal-Hydrogen Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ruckman, M W; Wiesmann, H; Strongin, M; Young, K; Fetcenko, M

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries. The anodes could be incorporated in thin film solid state Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped metal-hydrogen ratios exceeding and fast hydrogen charging and Nb films, these studies suggested that materials with those of commercially available metal hydride materials discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films-and multiiayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 µm thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for

  9. Imaging the uptake of gold nanoshells in live cells using plasmon resonance enhanced four wave mixing microscopy.

    Science.gov (United States)

    Garrett, Natalie; Whiteman, Matt; Moger, Julian

    2011-08-29

    Gold nanoshells (GNS) are novel metal nanoparticles exhibiting attractive optical properties which make them highly suitable for biophotonics applications. We present a novel investigation using plasmon-enhanced four wave mixing microscopy combined with coherent anti-Stokes Raman scattering (CARS) microscopy to visualize the distribution of 75 nm radius GNS within live cells. During a laser tolerance study we found that cells containing nanoshells could be exposed to nanoshell uptake using two donor molecules, NaHS and GYY4137. As GYY4137 concentration was increased from 10 µM to 1 mM, the nanoshell pixel percentage as a function of cell volume (PPCV) increased from 2.15% to 3.77%. As NaHS concentration was increased over the same range, the nanoshell PPCV decreased from 12.67% to 11.47%. The most important factor affecting uptake in this study was found to be the rate of H2S release, with rapid-release from NaHS resulting in significantly greater uptake.

  10. Reflectance spectroscopy of gold nanoshells: computational predictions and experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Alex W. H.; Lewinski, Nastassja A.; Lee, Min-Ho; Drezek, Rebekah A. [Rice University, Department of Bioengineering (United States)], E-mail: drezek@rice.edu

    2006-10-15

    Gold nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core-shell ratio as well as the overall size. Although optical properties of gold nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles ({approx}180 deg.) were observed at low nanoshell concentrations. Monte Carlo modeling of gold nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing nanoshells best suited for scattering-based optical methods.

  11. Reflectance spectroscopy of gold nanoshells: computational predictions and experimental measurements

    Science.gov (United States)

    Lin, Alex W. H.; Lewinski, Nastassja A.; Lee, Min-Ho; Drezek, Rebekah A.

    2006-10-01

    Gold nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core-shell ratio as well as the overall size. Although optical properties of gold nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles ( 180°) were observed at low nanoshell concentrations. Monte Carlo modeling of gold nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing nanoshells best suited for scattering-based optical methods.

  12. In-vitro Investigations of Skin Closure using Diode Laser and Protein Solder Containing Gold Nanoshells

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Nourbakhsh

    2010-12-01

    Full Text Available Introduction: Laser tissue soldering is a new technique for repair of various tissues including the skin, liver, articular cartilage and nerves and is a promising alternative to suture. To overcome the problems of thermal damage to surrounding tissues and low laser penetration depth, some exogenous chromophores such as gold nanoshells, a new class of nanoparticles consisting of a dielectric core surrounded by a thin metal shell, are used. The aims of this study were to use two different concentrations of gold nanoshells as the exogenous material for skin tissue soldering and also to examine the effects of laser soldering parameters on the properties of the repaired skin. Material and Methods: Two mixtures of albumin solder and different concentrations of gold nanoshells were prepared. A full thickness incision of 2×20 mm2 was made on the surface and after placing 50 μl of the solder mixture on the incision, an 810 nm diode laser was used to irradiate it at different power densities. The changes of tensile strength, σt, due to temperature rise, number of scan (Ns, and scan velocity (Vs were investigated. Results: The results showed that the tensile strength of the repaired skin increased with increasing irradiance for both gold nanoshell concentrations. In addition, at constant laser irradiance (I, the tensile strength of the repaired incision increased with increasing Ns and decreasing Vs. In our case, this corresponded to st = 1610 g/cm2 at I ~ 60 Wcm-2, T ~ 65ºC, Ns = 10 and Vs = 0.2 mms-1. Discussion and Conclusion: Gold nanoshells can be used as an indocyanine green dye (ICG alterative for laser tissue soldering.  Although by increasing the laser power density, the tensile strength of the repaired skin increases, an optimum power density must be considered due to the resulting increase in tissue temperature.

  13. Galvanic Synthesis of Hollow Gold Nanoshells

    Science.gov (United States)

    2015-02-01

    pulses in the NIR.2 The advantage of hollow nanoshells over solid gold (Au) or silver (Ag) nanoparticles , or alloys thereof,3 is that the...Karna SP. Synthesis of gold and silver nanoparticles and characterization of structural, optical, and electronic properties. Aberdeen Proving Ground...

  14. Simple control of surface topography of gold nanoshells by a surfactant-less seeded-growth method.

    Science.gov (United States)

    Topete, Antonio; Alatorre-Meda, Manuel; Villar-Álvarez, Eva M; Cambón, Adriana; Barbosa, Silvia; Taboada, Pablo; Mosquera, Víctor

    2014-07-23

    We report the synthesis of branched gold nanoshells (BGNS) through a seeded-growth surfactant-less method. This was achieved by decorating chitosan-Pluronic F127 stabilized poly(lactic-co-gycolic) acid nanoparticles (NPs) with Au seeds (NP-seed), using chitosan as an electrostatic self-assembling agent. Branched shells with different degrees of anisotropy and optical response were obtained by modulating the ratios of HAuCl4/K2CO3 growth solution, ascorbic acid (AA) and NP-seed precursor. Chitosan and AA were crucial in determining the BGNS size and structure, acting both as coreductants and structure directing growth agents. Preliminary cytotoxicity experiments point to the biocompatibility of the obtained BGNS, allowing their potential use in biomedical applications. In particular, these nanostructures with "hybrid" compositions, which combine the features of gold nanoshells and nanostars showed a better performance as surface enhanced Raman spectroscopy probes in detecting intracellular cell components than classical smoother nanoshells.

  15. Optimization of silver-dielectric-silver nanoshell for sensing applications

    Science.gov (United States)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  16. Optimization of silver-dielectric-silver nanoshell for sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Shirzaditabar, Farzad; Saliminasab, Maryam [Department of Physics, Razi University, Kermanshah 67144-15111 (Iran, Islamic Republic of)

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  17. Multifunctional Metal Matrix Composite Filament Wound Tank Liners Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Metal Matrix Composite (MMC) materials offer tremendous potential for lightweight propellant and pressurant tankage for space applications. Thin MMC liners for COPVs...

  18. Multifunctional Metal/Polymer Composite Fiber for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovation Research Phase I Program, Syscom Technology, Inc. (STI) will fabricate a metallized multifunctional composite fiber from a...

  19. Synthesis and processing of composites by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.; Ewsuk, K.G. [Sandia National Laboratories, Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)] [and others

    1995-05-01

    Ceramic-metal composites are being developed because their high stiffness-to weight ratios, good fracture toughness, and variable electrical and thermal properties give them advantages over more conventional materials. However, because ceramic-metal composite components presently are more expensive than monolithic materials, improvements in processing are required to reduce manufacturing costs. Reactive metal penetration is a promising new method for making ceramic- and metal-matrix composites that has the advantage of being inherently a net-shape process. This technique, once fully developed, will provide another capability for manufacturing the advanced ceramic composites that are needed for many light-weight structural and wear applications. The lower densities of these composites lead directly to energy savings in use. Near-net-shape fabrication of composite parts should lead to additional savings because costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research program are: (1) to identify feasible compositional systems for making composites by reactive metal penetration; (2) to understand the mechanism(s) of composite formation by reactive metal penetration; and (3) to learn how to control and optimize reactive metal penetration for economical production of composites and composite coatings.

  20. Metallic glass nanostructures of tunable shape and composition.

    Science.gov (United States)

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-04-22

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties.

  1. Fracture toughness in metal matrix composites

    Directory of Open Access Journals (Sweden)

    Perez Ipiña J.E.

    2000-01-01

    Full Text Available Evaluations of the fracture toughness in metal matrix composites (Duralcan reinforced with 15% of Al(20(3 and SiC are presented in this work. The application of Elastic Plastic Fracture Mechanics is discussed and the obtained values are compared with the ones obtained by means of Linear Elastic Fracture Mechanics. Results show that J IC derived K JC values are higher than the corresponding values obtained by direct application of the linear elastic methodology. The effect of a heat treatment on the material fracture toughness was also evaluated in which the analyzed approaches showed, not only different toughness values, but also opposite tendencies. A second comparison of the J IC and K JC values obtained in this work with toughness values reported in the literature is presented and discussed.

  2. Gain assisted harmonic generation in near-zero permittivity metamaterials made of plasmonic nanoshells

    CERN Document Server

    Vincenti, Maria Antonietta; de Ceglia, Domenico; Capolino, Filippo; Scalora, Michael

    2012-01-01

    We investigate enhanced harmonic generation processes in gain-assisted, near-zero permittivity metamaterials composed of spherical plasmonic nanoshells. We report the presence of narrow-band features in transmission, reflection and absorption induced by the presence of an active material inside the core of the nanoshells. The damping-compensation mechanism used to achieve the near-zero effective permittivity condition also induces a significant increase in field localization and strength and, consequently, enhancement of linear absorption. When only metal nonlinearities are considered, second and third harmonic generation efficiencies obtained by probing the structure in the vicinity of the near-zero permittivity condition approach values as high as for irradiance value as low as . These results clearly demonstrate that a relatively straightforward path now exists to the development of exotic and extreme nonlinear optical phenomena in the KW/cm2 range

  3. Preparation and characteristics of CNT-metal composites

    CSIR Research Space (South Africa)

    Pityana, SL

    2006-01-01

    Full Text Available The success in keeping carbon nanotubes (CNT) bonded to stainless steel provides a possible method for the preparation of CNT-metal composites. Alternative methods for the preparation of CNT-metal composites include hot pressing, sintering, etc...

  4. Profiling the Near field of Nanoshells Using Surface Enhanced Raman Spectroscopy

    Science.gov (United States)

    Lal, Surbhi

    2005-03-01

    There is tremendous interest in the enhancement of electromagnetic fields near metal surfaces. The spatial extent of the near field as a function of distance from the metal surface is of particular interest for applications such as surface enhanced Raman spectroscopy. By using specially designed molecular scaffolds with Raman-active constituents, we measure the profile of this fringing field at a nanoshell surface. Nanoshells are colloidal particles composed of a silica core covered by a gold shell, which exhibit a tunable plasmon resonance; close to this resonance there is a strong enhancement of the electromagnetic near field. The molecular scaffolds consist of polyadenine DNA strands as tethers with a terminal fluorescein molecule. By varying the length of the DNA strand, the fluorescein molecule is placed at controlled distances from the nanoshell surface. Both the DNA scaffold and the terminal fluorescein molecule provide us with independent SERS Stokes modes whose relative intensities permit us to map the average spatial decay length of the near field of the nanoparticle at its plasmon resonance.

  5. Noble Metal/Ceramic Composites in Flame Processes

    DEFF Research Database (Denmark)

    Schultz, Heiko; Madler, Lutz; Strobel, Reto

    Noble metals on metal oxides play a major role in the performance of electrodes, catalysts and many other applications. Today, impregnation of noble metals on metal oxides is done in the wet phase involving multiple steps. The physicochemical nature of the support, the precursor and the reaction...... conditions influence the resulting noble metal particles size in those systems [1]. For every specific application the particle size and the metal/metal oxide interaction affect the performance of these nano-composite materials [2]. Recently, aerosol processes have been successfully used to produce platinum......-7] with metal particles smaller than 7 nm on the metal oxide [3-7]. This makes them attractive for reactions with mass transfer limitation and for high temperature applications. An intimate contact of the two particles was observed in HRTEM images [3-5,7]. For a specific metal oxide support the metal particle...

  6. Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

    Science.gov (United States)

    Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Nazem, Negin (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2017-01-01

    A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

  7. Tailored synthesis of superparamagnetic gold nanoshells with tunable optical properties.

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.; Ge, J.; Goebl, J.; Hu, Y.; Sun, Y.; Yin, Y.; Center for Nanoscale Materials; Univ. of California at Riverside

    2010-05-04

    Multifunctional Au nanoshells with tunable optical properties and fast magnetic response have been fabricated through a sequence of sol-gel, surface-protected etching, and seed-mediated growth processes. The use of a porous silica layer enhances the uniformity of nanoshell growth, the reproducibility of the synthesis, and the structural and optical stability of the products.

  8. Negative Refractive Index in Optics of Metal-Dielectric Composites

    OpenAIRE

    Kildishev, A.V.; Cai, W; Chettiar, U K; Yuan, H.-K.; Sarychev, A. K.; Drachev, V. P.; Shalaev, V. M.

    2005-01-01

    Specially designed metal-dielectric composites can have a negative refractive index in the optical range. Specifically, it is shown that arrays of single and paired nanorods can provide such negative refraction. For pairs of metal rods, a negative refractive index has been observed at 1.5 micrometer. The inverted structure of paired voids in metal films may also exhibit a negative refractive index. A similar effect can be accomplished with metal strips in which the refractive index can reach ...

  9. Low cost aluminium metal matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Withers, G.

    2007-03-15

    Low cost, light weight Ultalite{reg_sign} is an Aluminium Metal Matrix Composite (AL-MMC) which utilises wear resistant ceramic particles derived from flyash. Ultalite AL-MMC typically contains between 10 and 30 per cent ceramic particles, and is formulated for the manufacture of wear resistant automotive components. Due to its low density and ease of processing into net shape die casting, Ultalite AL-MMC provides weight savings of up to 60 per cent over components fabricated from cast iron, thereby providing improved fuel efficiency with reduced greenhouse emissions. The original flyash material was sourced from a black coal power station in Queensland, where it contained a wide range of particles sizes. To narrow the size range and to remove impurities, a proprietary pretreatment developed by Dr Thomas Robl and co-researchers at the University of Kentucky was employed. The University of Kentucky developed the technology for the classification and benefaction of flyash to produce high-grade Pozzolan, which is used in Portland Cement product. This technology is now being applied to the production of Ultalite AL-MMC. Testing performed by Dr Robl has shown that the proprietary technology can eliminate the hollow particles, extract detrimental carbon-based impurities and remove the extremely fine and coarse particles. All that remains are dense ceramic particles with an average particle size of approximately 30 {mu}m. 9 refs., 3 figs.

  10. Best practices for making high integrity lightweight metal castings- molten metal composition and cleanliness control

    Institute of Scientific and Technical Information of China (English)

    Qigui Wang

    2014-01-01

    To make high integrity lightweight metal castings, best practices are required in various stages of casting and heat treatment processes, including liquid metal composition and quality control, casting and gating/riser system design, and process optimization. This paper presents best practices for liquid metal processing and quality assurance of molten metal in both melting and mold ifling. Best practices for other aspects of lightweight metal casting wil be published separately.

  11. Synthesis and processing of composites by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)] [and others

    1997-04-01

    Achieving better performance in commercial products and processes often is dependent on availability of new and improved materials. Ceramic-metal composites have advantages over more conventional materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. However, ceramic composites will be more widely used only when their costs are competitive with other materials and when designers have more confidence in their reliability. Over the past four years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that, with sufficient development, reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts is a significant advantage because costly and energy intensive grinding and machining operations are substantially reduced, and the waste generated from such finishing operations is minimized. The most promising compositions to date consist of Al and Al{sub 2}O{sub 3}; thus, these composites should be of particular interest to the aluminum industry. The goals of this ceramic-metal composite research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; (3) to control and optimize the process so that composites and composite coatings can be made economically; and (4) to apply R&D results to problems of interest to the aluminum industry.

  12. Enormous enhancement of electric field in active gold nanoshells

    Science.gov (United States)

    Jiang, Shu-Min; Wu, Da-Jian; Wu, Xue-Wei; Liu, Xiao-Jun

    2014-04-01

    The electric field enhancement properties of an active gold nanoshell with gain material inside have been investigated by using Mie theory. As the gain coefficient of the inner core increases to a critical value, a super-resonance appears in the active gold nanoshell, and enormous enhancements of the electric fields can be found near the surface of the particle. With increasing shell thickness, the critical value of the gain coefficient for the super-resonance of the active gold nanoshell first decreases and then increases, and the corresponding surface enhanced Raman scattering (SERS) enhancement factor (G factor) also first increases and then decreases. The optimized active gold nanoshell can be obtained with an extremely high SERS G factor of the order of 1019-1020. Such an optimized active gold nanoshell possesses a high-efficiency SERS effect and may be useful for single-molecule detection.

  13. High Temperature Self-Healing Metallic Composite

    Science.gov (United States)

    Kutelia, E. R.; Bakhtiyarov, S. I.; Tsurtsumia, O. O.; Bakhtiyarov, A. S.; Eristavi, B.

    2012-01-01

    This work presents the possibility to realize the self healing mechanisms for heterogeneous architectural metal/ceramic high temperature sandwich thermal barrier coating systems on the surfaces refractory metals by analogy of wound healing in the skin.

  14. Novel method of polymer/low-melting-point metal alloy/light metal fiber composite fabrication

    Directory of Open Access Journals (Sweden)

    J. Park

    2016-07-01

    Full Text Available A novel method of polymer/low-melting-point metal alloy (LMA/light metal fiber composite fabrication is proposed to solve problems of polymer/metal composites. The first step is mixing light metal particles with LMA at a temperature above the melting point of the LMA. The second step is cold extrusion of the LMA/light metal particles to fabricate LMA/light metal fibers. Thus, the LMA/light metal fibers with a density of ~4.5 g/cm3 were obtained. The last step is compounding a polymer with the LMA/light metal fibers at the processing temperature of the polymer above the melting points of the LMA. The effects of the length and the cross-sectional shape of light metal fiber on the morphology of the LMA/light metal fibers in the polymer matrix were studied, as were electrical conductivities and mechanical properties of the composites. As the length and/or the cross-sectional aspect ratio of the fibers was increased, the domains of LMA/light metal fibers formed more networks so that the electrical conductivity increased, and specific surface area of the domains increased so that notched Izod impact strength was improved. Thus, the polymer/LMA/light metal fiber composites were fabricated without degrading processability even at 60 vol% loading and the electrical conductivities over 103 S/cm were achieved.

  15. Experimental investigations on mechanical behavior of aluminium metal matrix composites

    Science.gov (United States)

    Rajesh, A. M.; Kaleemulla, Mohammed

    2016-09-01

    Today we are widely using aluminium based metal matrix composite for structural, aerospace, marine and automobile applications for its light weight, high strength and low production cost. The purpose of designing metal matrix composite is to add the desirable attributes of metals and ceramics to the base metal. In this study we developed aluminium metal matrix hybrid composite by reinforced Aluminium7075 alloy with silicon carbide (SiC) and aluminium oxide (alumina) by method of stir casting. This technique is less expensive and very effective. The Hardness test and Wear test were performed on the specimens which are prepared by stir casting techniques. The result reveals that the addition of silicon carbide and alumina particles in aluminium matrix improves the mechanical properties.

  16. Laser Assisted Machining of Metal Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Metal matrix composites (MMC's) are of great interest in aerospace applications where their high specific strength provides a weight saving alternative to standard...

  17. Electromagnetic shielding of polymer-matrix composites with metallic nanoparticles

    National Research Council Canada - National Science Library

    Jalali, M; Dauterstedt, S; Michaud, A; Wuthrich, R

    2011-01-01

    To improve electromagnetic (EM) shielding and especially absorption of carbon fibre reinforced polymer-matrix composites for aircraft applications in high frequencies, the inclusion of metallic nanoparticles of iron, cobalt, nickel...

  18. Catalytic self-limited assembly at hard templates: a mesoscale approach to graphene nanoshells for lithium-sulfur batteries.

    Science.gov (United States)

    Peng, Hong-Jie; Liang, Jiyuan; Zhu, Lin; Huang, Jia-Qi; Cheng, Xin-Bing; Guo, Xuefeng; Ding, Weiping; Zhu, Wancheng; Zhang, Qiang

    2014-11-25

    Hollow nanostructures afford intriguing structural features ranging from large surface area and fully exposed active sites to kinetically favorable mass transportation and tunable surface permeability. The unique properties and potential applications of graphene nanoshells with well-defined small cavities and delicately designed graphene shells are strongly considered. Herein, a mesoscale approach to fabricate graphene nanoshells with a single or few graphene layers and quite small diameters through a catalytic self-limited assembly of nanographene on in situ formed nanoparticles was proposed. The graphene nanoshells with a diameter of ca. 10-30 nm and a pore volume of 1.98 cm(3) g(-1) were employed as hosts to accommodate the sulfur for high-rate lithium-sulfur batteries. A very high initial discharge capacity of 1520 mAh g(-1), corresponding to 91% sulfur utilization rate at 0.1 C, was achieved on a graphene nanoshell/sulfur composite with 62 wt % loading. A very high retention of 70% was maintained when the current density increased from 0.1 C to 2.0 C, and an ultraslow decay rate of 0.06% per cycle during 1000 cycles was detected.

  19. Steel-SiC Metal Matrix Composite Development

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Don D.

    2005-07-17

    The goal of this project is to develop a method for fabricating SiC-reinforced high-strength steel. We are developing a metal-matrix composite (MMC) in which SiC fibers are be embedded within a metal matrix of steel, with adequate interfacial bonding to deliver the full benefit of the tensile strength of the SiC fibers in the composite.

  20. Review on preparation techniques of particle reinforced metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper reviews the investigation status of the techniques for preparation of metal matrix composites and the research outcomes achieved recently. The mechanisms, characteristics, application ranges and levels of development of these preparatior techniques are analyzed. The advantages and the disadvantages of each technique are synthetically evaluated. Lastly, the future directions of research and the prospects for the preparation techniques of metal matrix composites are forecasted.

  1. Review on preparation techniques of particle reinforced metal matrix composites

    Directory of Open Access Journals (Sweden)

    HAO Bin

    2006-02-01

    Full Text Available This paper reviews the investigation status of the techniques for preparation of metal matrix composites and the research outcomes achieved recently. The mechanisms, characteristics, application ranges and levels of development of these preparation techniques are analyzed. The advantages and the disadvantages of each technique are synthetically evaluated. Lastly, the future directions of research and the prospects for the preparation techniques of metal matrix composites are forecasted.

  2. Surface-modified gold nanoshells for enhanced cellular uptake.

    Science.gov (United States)

    Liang, Zhongshi; Liu, Yun; Li, Xiangyang; Wu, Qinge; Yu, Jiahui; Luo, Shufang; Lai, Lihui; Liu, Shunying

    2011-09-15

    Gold nanoshells have shown a great potential for use as agents in a wide variety of biomedical applications, and some of which require the delivery of large numbers of gold nanoshells onto or into the cells. Here, we develop a ready method to enhance the cellular uptake of gold nanoshells by modifying with meso-2,3-dimercaptosuccinic acid (DMSA). The quantifiable technique of inductively coupled plasma atomic emissions spectroscopy (ICP-AES) and transmission electron microscopy (TEM) were used to investigate the cellular uptake of unmodified and DMSA-modified gold nanoshells. Three cell lines (RAW 264.7, A549, and BEL-7402) were involved and the results indicated that the cellular uptake of the DMSA-modified gold nanoshells was obviously enhanced versus the unmodified gold nanoshells. The reason possibly lies in the nonspecific adsorption of serum protein on the DMSA-modified gold nanoshells (DMSA-GNs), which consequently enhanced the cellular uptake. As a continued effort, in vitro experiments with endocytic inhibitors suggested the DMSA-GNs internalized into cells via receptor-mediated endocytosis (RME) pathway. This study has provided a valuable insight into the effects of surface modification on cellular uptake of nanoparticles.

  3. Mechanically Tunable Hollow Silica Ultrathin Nanoshells for Ultrasound Contrast Agents

    Science.gov (United States)

    Liberman, A.; Wang, J.; Lu, N.; Viveros, R.D.; Allen, C. A.; Mattrey, R.F.; Blair, S.L.; Trogler, W.C.; Kim, M. J.; Kummel, A.C.

    2015-01-01

    Perfluoropentane (PFP) gas filled biodegradable iron-doped silica nanoshells have been demonstrated as long-lived ultrasound contrast agents. Nanoshells are synthesized by a sol-gel process with tetramethyl orthosilicate (TMOS) and iron ethoxide. Substituting a fraction of the TMOS with R-substituted trialkoxysilanes produces ultrathin nanoshells with varying shell thicknesses and morphologies composed of fused nanoflakes. The ultrathin nanoshells had continuous ultrasound Doppler imaging lifetimes exceeding 3 hours, were twice as bright using contrast specific imaging, and had decreased pressure thresholds compared to control nanoshells synthesized with just TMOS. Transmission electron microscopy (TEM) showed that the R-group substituted trialkoxysilanes could reduce the mechanically critical nanoshell layer to 1.4 nm. These ultrathin nanoshells have the mechanical behavior of weakly linked nanoflakes but the chemical stability of silica. The synthesis can be adapted for general fabrication of three-dimensional nanostructures composed of nanoflakes, which have thicknesses from 1.4–3.8 nm and diameters from 2–23 nm. PMID:26955300

  4. Plasmonic Induced Potential in Metal-Semiconductor Composits

    CERN Document Server

    Shahin, Shiva; Norwood, Robert A

    2015-01-01

    We utilize experimental tools such as conductive atomic force microscopy and electrostatic force microscopy on photo-excited arrays of gold nanoparticles on indium tin oxide substrate. The nanoparticles are partially covered by a thin semiconductor polymer. The change in the current and potential profiles of the composite metal-semiconductor sample after excitation at plasmonic resonance frequency of metallic nanoparticles is analyzed.

  5. Compositions and methods for removal of toxic metals and radionuclides

    Science.gov (United States)

    Cuero, Raul G. (Inventor); McKay, David S. (Inventor)

    2007-01-01

    The present invention relates to compositions and methods for the removal of toxic metals or radionuclides from source materials. Toxic metals may be removed from source materials using a clay, such as attapulgite or highly cationic bentonite, and chitin or chitosan. Toxic metals may also be removed using volcanic ash alone or in combination with chitin or chitosan. Radionuclides may be removed using volcanic ash alone or in combination with chitin or chitosan.

  6. Compositions and methods of making and using metal-organic framework compositions

    KAUST Repository

    Mohideen, Mohamed Infas Haja

    2017-05-04

    Embodiments of the present disclosure include a metal-organic framework (MOF) composition comprising one or more metal ions, a plurality of organic ligands, and a solvent, wherein the one or more metal ions associate with the plurality of organic ligands sufficient to form a MOF with kag topology. Embodiments of the present disclosure further include a method of making a MOF composition comprising contacting one or more metal ions with a plurality of organic ligands in the presence of a solvent, sufficient to form a MOF with kag topology, wherein the solvent comprises water only. Embodiments of the present disclosure also describe a method of capturing chemical species from a fluid composition comprising contacting a MOF composition with kag topology and pore size of about 3.4Å to 4.8Å with a fluid composition comprising two or more chemical species and capturing one or more captured chemical species from the fluid composition.

  7. Spin Excitations in Dissipative Ferromagnetic Nanoshells

    Directory of Open Access Journals (Sweden)

    V.V. Kulish

    2016-10-01

    Full Text Available In the paper, dipole-exchange radial-angular spin excitations in a spherical ferromagnetic nanoshell are investigated. For such excitations, a differential equation for the magnetic potential is found, with account for the magnetic dipole-dipole interaction, the exchange interaction, the anisotropy effects and the dissipation. The equation is solved for the three cases – the case of a thin shell, the case of short waves and the case of radial excitations. For each of these cases, the dispersion relation and the spectrum of possible excitation frequencies are found.

  8. Amorphous nanoshell formed through random growth and related plasmonic behaviors

    Science.gov (United States)

    Wang, Yuwei; Shen, Hongming; He, Yingbo; Cheng, Yuqing; Perriat, Pascal; Martini, Matteo; Tillement, Olivier; Gong, Qihuang; Lu, Guowei

    2014-08-01

    The optical properties of gold nanoshell formed through random growth process were numerically investigated by employing finite-difference time-domain method. The growth process can be divided approximately into four stages according to the optical spectra and 3D morphology. The incomplete nanoshell with surface coverage ratio (R) around 70% was found to form surface ‘hot spots' with high field enhancement, which are useful for surface enhanced Raman scattering. Additionally, high Purcell factor and quantum efficiency at the core center for the nanoshells with R ∼ 90% are suitable for encapsulated fluorescent probe that can exploit the high surface plasmonic enhancement effect.

  9. Metal-composite adhesion based on diazonium chemistry.

    Science.gov (United States)

    Oweis, Yara; Alageel, Omar; Kozak, Paige; Abdallah, Mohamed-Nur; Retrouvey, Jean-Marc; Cerruti, Marta; Tamimi, Faleh

    2017-08-07

    Composite resins do not adhere well to dental alloys. This weak bond can result in failure at the composite-metal interface in fixed dental prostheses and orthodontic brackets. The aim of this study was to develop a new adhesive, based on diazonium chemistry, to facilitate chemical bonding between dental alloys and composite resin. Samples of two types of dental alloys, stainless steel and cobalt chromium were primed with a diazonium layer in order to create a surface coating favorable for composite adhesion. Untreated metal samples served as controls. The surface chemical composition of the treated and untreated samples was analyzed by X-ray photoelectron spectroscopy (XPS) and the tensile strength of the bond with composite resin was measured. The diazonium adhesive was also tested for shear bond strength between stainless steel orthodontic brackets and teeth. XPS confirmed the presence of a diazonium coating on the treated metals. The coating significantly increased the tensile and shear bond strengths by three and four folds respectively between the treated alloys and composite resin. diazonium chemistry can be used to develop composite adhesives for dental alloys. Diazonium adhesion can effectively achieve a strong chemical bond between dental alloys and composite resin. This technology can be used for composite repair of fractured crowns, for crown cementation with resin based cements, and for bracket bonding. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Metal Matrix Composites Reinforced by Nano-Particles—A Review

    Directory of Open Access Journals (Sweden)

    Riccardo Casati

    2014-03-01

    Full Text Available Metal matrix composites reinforced by nano-particles are very promising materials, suitable for a large number of applications. These composites consist of a metal matrix filled with nano-particles featuring physical and mechanical properties very different from those of the matrix. The nano-particles can improve the base material in terms of wear resistance, damping properties and mechanical strength. Different kinds of metals, predominantly Al, Mg and Cu, have been employed for the production of composites reinforced by nano-ceramic particles such as carbides, nitrides, oxides as well as carbon nanotubes. The main issue of concern for the synthesis of these materials consists in the low wettability of the reinforcement phase by the molten metal, which does not allow the synthesis by conventional casting methods. Several alternative routes have been presented in literature for the production of nano-composites. This work is aimed at reviewing the most important manufacturing techniques used for the synthesis of bulk metal matrix nanocomposites. Moreover, the strengthening mechanisms responsible for the improvement of mechanical properties of nano-reinforced metal matrix composites have been reviewed and the main potential applications of this new class of materials are envisaged.

  11. Intrinsic manufacture of hollow thermoplastic composite/metal structures

    Science.gov (United States)

    Barfuss, Daniel; Grützner, Raik; Garthaus, Christian; Gude, Maik; Müller, Roland; Langrebe, Dirk

    2016-10-01

    In contrast to common and classical joining technologies for composite/metal hybrid structures such as bonding and riveting, profile and contour joints offer a promising potential for novel lightweight hybrid structures. First and foremost, joining systems with a form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. This paper demonstrates the theoretical and technological principals for a resource efficient design and production of highly loaded thermoplastic composite profile structures with integrated metallic load introduction elements and a multi scale form closure. The hybrid structures are produced in an integral blow moulding process in which a braided tape-preform is simultaneously consolidated and formed into the metallic load introduction element. These metallic load introduction elements are manufactured in a two-stage process of external and internal hydroforming, after forming simulations have assured process stability for consistent quality.

  12. Hybrid Composite Structures: Multifunctionality through Metal Fibres

    NARCIS (Netherlands)

    Ahmed, T.

    2009-01-01

    The introduction of fibre reinforced polymer composites into the wings and fuselages of the newest aircraft are changing the design and manufacturing approach. Composites provide greater freedom to designers who want to improve aircraft performance in an affordable way. In this quest, researchers ar

  13. Polymer/mesoporous metal oxide composites

    Science.gov (United States)

    Ver Meer, Melissa Ann

    Understanding the nature of the interfacial region between an organic polymer matrix and an inorganic filler component is essential in determining how this region impacts the overall bulk properties of the organic/inorganic hybrid composite material. In this work, polystyrene was used as the model polymer matrix coupled with silica-based filler materials to investigate the nature of structure-property relationships in polymer composites. Initial work was conducted on synthesis and characterization of colloidal and mesoporous silica particles melt blended into the polystyrene matrix. Modification of the interface was accomplished by chemically bonding the silica particles with the polystyrene chains through polymerization from the particle surface via atom transfer radical polymerization. High molecular weight polystyrene chains were formed and bulk test samples were evaluated with increased thermal stability of the grafted polymer composite system versus equivalent melt blended polymer composites. Polymer grafting was also conducted from the internal pores of mesoporous silica, further improving the thermal stability of the composite system without degrading dynamic mechanical properties. Characterization of the polymer composites was conducted with gel permeation chromatography, transmission electron microscopy, thermogravimetric analysis and dynamic mechanical analysis. It was also discovered during the polystyrene-silica composite studies that amorphous polystyrene can possess a less mobile phase, evident in a second peak of the loss tangent (tan delta). The long annealing times necessitated by the mesoporous silica composites were replicated in as received polystyrene. This new, less mobile phase is of particular interest in determining the mobility of polymer chains in the interfacial region.

  14. New transparent conductive metal based on polymer composite

    Energy Technology Data Exchange (ETDEWEB)

    Keshavarz Hedayati, Mehdi; Jamali, Mohammad [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Strunkus, Thomas; Zaporochentko, Vladimir; Faupel, Franz [Multicomponent Materials, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Elbahri, Mady [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Helmholtz-Zentrum Geesthacht GmbH, Institute of Polymer Research, Nanochemistry and Nanoengineering (Germany)

    2011-07-01

    Currently great efforts are made to develop new kind of transparent conductors (TCs) to replace ITO. In this regard different materials and composites have been proposed and studied including conductive polymers, carbon nanotubes (CNTs), metal grids, and random networks of metallic nanowires. But so far none of them could be used as a replacing material, since either they are either fragile and brittle or their electrical conductivity is below the typical ITO. Thin metallic films due to their high electrical conductivity could be one of the best replacing materials for ITO, however their poor transparency makes their application as TCs limited. Here we design and fabricate a new polymeric composite coating which enhances the transparency of the thin metal film up to 100% relative to the initial value while having a high electrical conductivity of typical metals. Therefore our proposed device has a great potential to be used as new transparent conductor.

  15. Cell surface engineering with edible protein nanoshells.

    Science.gov (United States)

    Drachuk, Irina; Shchepelina, Olga; Harbaugh, Svetlana; Kelley-Loughnane, Nancy; Stone, Morley; Tsukruk, Vladimir V

    2013-09-23

    Natural protein (silk fibroin) nanoshells are assembled on the surface of Saccharomyces cerevisiae yeast cells without compromising their viability. The nanoshells facilitate initial protection of the cells and allow them to function in encapsulated state for some time period, afterwards being completely biodegraded and consumed by the cells. In contrast to a traditional methanol treatment, the gentle ionic treatment suggested here stabilizes the shell silk fibroin structure but does not compromise the viability of the cells, as indicated by the fast response of the encapsulated cells, with an immediate activation by the inducer molecules. Extremely high viability rates (up to 97%) and preserved activity of encapsulated cells are facilitated by cytocompatibility of the natural proteins and the formation of highly porous shells in contrast to traditional polyelectrolyte-based materials. Moreover, in a high contrast to traditional synthetic shells, the silk proteins are biodegradable and can be consumed by cells at a later stage of growth, thus releasing the cells from their temporary protective capsules. These on-demand encapsulated cells can be considered a valuable platform for biocompatible and biodegradable cell encapsulation, controlled cell protection in a synthetic environment, transfer to a device environment, and cell implantation followed by biodegradation and consumption of protective protein shells.

  16. Nanoshells as a high-pressure gauge

    Science.gov (United States)

    Tempere, Jacques; van den Broeck, Nick; Putteneers, Katrijn; Silvera, Isaac

    2012-02-01

    Nanoshells, consisting of multiple spherical layers, have an extensive list of applications, usually performing the function of a probe. We add a new application to this list in the form of a high-pressure gauge in a Diamond Anvil Cell (DAC). In a DAC, where high pressures are reached by pressing two diamonds together, existing gauges fail at higher pressures because of calibration difficulties and obscuring effects in the diamonds. The nanoshell gauge does not face this issue since its optical spectrum can be engineered by altering the thickness of its layers. Furthermore their properties are measured by broad band optical transmission spectroscopy leading to a very large signal-to-noise ratio even in the multi-megabar pressure regime where ruby measurements become challenging. Theoretical calculations based on the Maxwell equations in a spherical geometry combined with the Vinet equation of state show that a three-layer geometry (SiO2-Au-SiO2) indeed has a measurable pressure-dependent optical response desirable for gauges.

  17. Synthesis of porous gold nanoshells by controlled transmetallation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pattabi, Manjunatha, E-mail: manjupattabi@yahoo.com; M, Krishnaprabha [Department of Materials Science, Mangalore University, Mangalagangothri-574199 (India)

    2015-06-24

    Aqueous synthesis of porous gold nanoshells in one step is carried out through controlled transmetallation (TM) reaction using a naturally available egg shell membrane (ESM) as a barrier between the sacrificial silver particles (AgNPs) and the gold precursor solution (HAuCl{sub 4}). The formation of porous gold nanoshells via TM reaction is inferred from UV-Vis spectroscopy and the scanning electron microscopic (SEM) studies.

  18. The assessment of metal fiber reinforced polymeric composites

    Science.gov (United States)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  19. Optical absorption analysis and optimization of gold nanoshells.

    Science.gov (United States)

    Tuersun, Paerhatijiang; Han, Xiang'e

    2013-02-20

    Gold nanoshells, consisting of a nanoscale dielectric core coated with an ultrathin gold shell, have wide biomedical applications due to their strong optical absorption properties. Gold nanoshells with high absorption efficiencies can help to improve these applications. We investigate the effects of the core material, surrounding medium, core radius, and shell thickness on the absorption spectra of gold nanoshells by using the light-scattering theory of a coated sphere. Our results show that the position and intensity of the absorption peak can be tuned over a wide range by manipulating the above-mentioned parameters. We also obtain the optimal absorption efficiencies and structures of hollow gold nanoshells and gold-coated SiO(2) nanoshells embedded in water at wavelengths of 800, 820, and 1064 nm. The results show that hollow gold nanoshells possess the maximum absorption efficiency (5.42) at a wavelength of 800 nm; the corresponding shell thickness and core radius are 4.8 and 38.9 nm, respectively. They can be used as the ideal photothermal conversation particles for biomedical applications.

  20. High-Performance Metal/Carbide Composites with Far-From-Equilibrium Compositions and Controlled Microstructures

    OpenAIRE

    Hu, Liangfa; O’Neil, Morgan; Erturun, Veysel; Benitez, Rogelio; Proust, Gwénaëlle; Karaman, Ibrahim; Radovic, Miladin

    2016-01-01

    The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow...

  1. Nano and hybrid aluminum based metal matrix composites: an overview

    Directory of Open Access Journals (Sweden)

    Muley Aniruddha V.

    2015-01-01

    Full Text Available Aluminium matrix composites (AMCs are potential light weight engineering materials with excellent properties. AMCs find application in many areas including automobile, mining, aerospace and defence, etc. Due to technological advancements, it is possible to use nano sized reinforcement in Al matrix. Nano sized reinforcements enhance the properties of Al matrix compared to micro sized reinforcements. Hybrid reinforcement imbibe superior properties to aluminium matrix composites as compared with Al composites having single reinforcement. This paper is focused on overview of development in the field of Al based metal matrix with nano and hybrid aluminium based composites.

  2. High-Performance Metal/Carbide Composites with Far-From-Equilibrium Compositions and Controlled Microstructures

    Science.gov (United States)

    Hu, Liangfa; O’Neil, Morgan; Erturun, Veysel; Benitez, Rogelio; Proust, Gwénaëlle; Karaman, Ibrahim; Radovic, Miladin

    2016-10-01

    The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow region of the Ti-Al-C phase diagram and readily reacts with Al. This kind of reactive systems challenges conventional methods for successfully processing corresponding metal-ceramic composites. Al alloy/Ti2AlC composites with controlled microstructures, various volume ratios of constituents (40/60 and 27/73) and metallic phase sizes (42–83 μm, 77–276 μm, and 167–545 μm), are obtained using the Ti2AlC foams with different pore structures as preforms for molten metal (Al alloy) infiltration. The resulting composites are lightweight and display exceptional mechanical properties at both ambient and elevated temperatures. These structures achieve a compressive strength that is 10 times higher than the yield strength of the corresponding peak-aged Al alloy at ambient temperature and 14 times higher at 400 °C. Possible strengthening mechanisms are described, and further strategies for improving properties of those composites are proposed.

  3. Cavitation instabilities between fibres in a metal matrix composite

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2016-01-01

    Short fibre reinforced metal matrix composites (MMC) are studied here to investigate the possibility that a cavitation instability can develop in the metal matrix. The high stress levels needed for a cavitation instability may occur in metal–ceramic systems due to the constraint on plastic flow...... of transversely staggered fibres is here modelled by using an axisymmetric cell model analysis. First the critical stress level is determined for a cavitation instability in an infinite solid made of the Al matrix material. By studying composites with different distributions and aspect ratios of the fibres...... induced by bonding to the ceramics that only show elastic deformation. In an MMC the stress state in the metal matrix is highly non-uniform, varying between regions where shear stresses are dominant and regions where hydrostatic tension is strong. An Al–SiC whisker composite with a periodic pattern...

  4. Multi-scattering of electromagnetic waves by nanoshell aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ben Q., E-mail: benqli@umich.edu [University of Michigan, Department of Mechanical Engineering (United States); Liu Changhong, E-mail: liuch@sjtu.edu.cn [Shanghai Jiao Tong University, Department of Electrical Engineering (China)

    2012-05-15

    A general analytical expression is derived for calculating the total scattering cross-section of an aggregate of nanoparticles. The approach is based on the far zone approximation and repeated use of recursive relations for Bessel functions and Legendre polynomials. In comparison with the existing formula for total scattering cross-section, the expression converges faster and makes it easier to analyze the terms that characterize the interactive coupling between nanoparticles during multiple scattering of electromagnetic waves. The expressions are valid for particle aggregates in which no two particles are in direct contact. Calculated results compare well with measurements for a nanoshell dimer. For a linear chain of particles with the chain axis parallel to the polarization direction of the electric field, analysis shows that the red-shift of resonance peaks results primarily from electrons in metal shells of two adjacent particles oscillating out-of-phase to cancel each other's radiation effects. Multi-scattering in aggregates with more complex arrangements may be explained by combining the effects of linear particle chains.

  5. Mechanisms in turning of metal matrix composites: a review

    Directory of Open Access Journals (Sweden)

    Ravi Sekhar

    2015-04-01

    Full Text Available Metal matrix composites have evoked a keen interest from the automobile and aerospace sectors owing to their attractive mechanical properties and applications. Over the past two decades, researchers have unearthed many secrets pertaining to these advanced materials. This paper briefly reviews the research revelations of the mechanisms that make these materials so superior. Turning of metal matrix composites is focused in particular. Mechanisms such as particle fracture, particle pullout, debonding, dislocation phenomena, thermal softening, wear modes, surface generation, cutting forces, chip formation, strains and stresses are addressed. Discussions on related phenomena such as effects of tool coatings, adhesion, friction, microstructures and strain hardening are also presented.

  6. Composite yarns of multiwalled carbon nanotubes with metallic electrical conductivity.

    Science.gov (United States)

    Randeniya, Lakshman K; Bendavid, Avi; Martin, Philip J; Tran, Canh-Dung

    2010-08-16

    Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.

  7. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested

  8. Multifunctional Virus-Nanoshell Assembly for Targeted Hyperthermia and Viral Gene Therapy for Breast Cancer

    Science.gov (United States)

    2012-06-01

    cancer cells in synergy with gene therapy. We proposed to develop virus- nanoshell assemblies by attaching adeno-associated virus (AAV) to gold... nanoshells (Au NS) through chemical bonds. We have successfully completed majority of tasks 1 and 2 of our Statement of Work. Specifically, we have...therapy, virus, Au nanoshell Multifunctional Virus- Nanoshell Assembly for Targeted Hyperthermia and Viral Gene Therapy for Breast Cancer Dr. Fang Wei

  9. Dry sliding wear of heat treated hybrid metal matrix composites

    Science.gov (United States)

    Naveed, Mohammed; Khan, A. R. Anwar

    2016-09-01

    In recent years, there has been an ever-increasing demand for enhancing mechanical properties of Aluminum Matrix Composites (AMCs), which are finding wide applications in the field of aerospace, automobile, defence etc,. Among all available aluminium alloys, Al6061 is extensively used owing to its excellent wear resistance and ease of processing. Newer techniques of improving the hardness and wear resistance of Al6061 by dispersing an appropriate mixture of hard ceramic powder and whiskers in the aluminium alloy are gaining popularity. The conventional aluminium based composites possess only one type of reinforcements. Addition of hard reinforcements such as silicon carbide, alumina, titanium carbide, improves hardness, strength and wear resistance of the composites. However, these composites possessing hard reinforcement do posses several problems during their machining operation. AMCs reinforced with particles of Gr have been reported to be possessing better wear characteristics owing to the reduced wear because of formation of a thin layer of Gr particles, which prevents metal to metal contact of the sliding surfaces. Further, heat treatment has a profound influence on mechanical properties of heat treatable aluminium alloys and its composites. For a solutionising temperature of 5500C, solutionising duration of 1hr, ageing temperature of 1750C, quenching media and ageing duration significantly alters mechanical properties of both aluminium alloy and its composites. In the light of the above, the present paper aims at developing aluminium based hybrid metal matrix composites containing both silicon carbide and graphite and characterize their mechanical properties by subjecting it to heat treatment. Results indicate that increase of graphite content increases wear resistance of hybrid composites reinforced with constant SiC reinforcement. Further heat treatment has a profound influence on the wear resistance of the matrix alloy as well as its hybrid composites

  10. Metallic-fibre-reinforced ceramic-matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Prevost, F.; Schnedecker, G.; Boncoeur, M.

    1994-12-31

    A refractory metal wire cloth is embedded in an oxide ceramic matrix, using a plasma spraying technology, in order to elaborate composite plates. When mechanically tested, the composite fails with a pseudo-ductile fracture mode whereas the ceramic alone is originally brittle. It exhibits a higher fracture strength, and remains in the form of a single piece even when straining is important. No further heat treatment is needed after the original processing to reach these characteristics. (authors). 2 figs., 2 refs.

  11. Composition and thermodynamic properties of dense alkali metal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gabdullin, M.T. [NNLOT, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan); Ramazanov, T.S.; Dzhumagulova, K.N. [IETP, al-Farabi Kazakh National University, 71 al-Farabi Str., Almaty 050035 (Kazakhstan)

    2012-04-15

    In this work composition and thermodynamic properties of dense alkali metal plasmas (Li, Na) were investigated. Composition was derived by solving the Saha equations with corrections due to nonideality. The lowering of the ionization potentials was calculated on the basis of pseudopotentials by taking screening and quantum effects into account (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Parametric Study Of A Ceramic-Fiber/Metal-Matrix Composite

    Science.gov (United States)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1992-01-01

    Report describes computer-model parametric study of effects of degradation of constituent materials upon mechanical properties of ceramic-fiber/metal-matrix composite material. Contributes to understanding of weakening effects of large changes in temperature and mechanical stresses in fabrication and use. Concerned mainly with influences of in situ fiber and matrix properties upon behavior of composite. Particular attention given to influence of in situ matrix strength and influence of interphase degradation.

  13. High Activity of Hexagonal Ag/Pt Nanoshell Catalyst for Oxygen Electroreduction

    Directory of Open Access Journals (Sweden)

    Lee Chien-Liang

    2008-01-01

    Full Text Available Abstract Hexagonal Ag/Pt nanoshells were prepared by using a hexagonal Ag nanoplate as the displacement template and by introducing Pt ions. The prepared Ag/Pt nanoshells played the role of an electrocatalyst in an oxygen reduction process. Compared to spherical Pt and Ag/Pt nanoparticles, the hexagonal Ag/Pt nanoshells showed higher activity for oxygen electroreduction.

  14. Hollow nanoshell formation and collapse in binary solid solutions with large range of solubility

    Energy Technology Data Exchange (ETDEWEB)

    Gusak, A M; Zaporozhets, T V, E-mail: gusak@cdu.edu.u, E-mail: tvz@phys.cdu.edu.u [Cherkasy National University, 81, Boulevard Shevchenko, Cherkasy, 18031 (Ukraine)

    2009-10-14

    The formation of a solid solution hollow nanoshell from core-shell structure and collapse of this nanoshell into a compact particle is modelled by a phenomenological scheme and by Monte Carlo simulation. The cross-over between formation and collapse, and the criteria of nanoshell formation are analysed.

  15. Structure of metal matrix composites with an addition of tuff

    Directory of Open Access Journals (Sweden)

    M. Łach

    2010-07-01

    Full Text Available The article presents preliminary results of tests of metal matrix composites structure which was modified by an addition of powderedvolcanic tuff. Distribution and shape of ceramic particles as well as the quality of the bonding along the tuff- metal matrix interface werestudied. Depth of tuff element diffusion in the matrix as well as diffusion in tuff particles were checked. Micro-hardness and porosity of the composites were also tested. The tuff from Filipowice near the town of Krzeszowice was used for the tests. Powder metallurgy wasapplied to obtain the composites and the matrix materials were copper and 316L steel powders. The tuff was introduced in 2, 5 and 10 %by weight. To remove water from the channels of aluminosilicates, the tuff was baked at 850 oC for 4 hours and then cooled together withthe oven. The tests revealed good quality of the bonding of the tuff particles and the matrix and their even distribution. The addition of tuff improved the hardness of the composites and reduced their porosity which has great significance because of possible applications of this kind of materials in general and copper composites in particular. This gives grounds for further studies on volcanic tuff use in metal composites

  16. Durable hydrophobic coating composition for metallic surfaces and method for the preparation of the composition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiong

    2017-02-14

    A durable hydrophobic coating composition containing fluorinated silanes for metallic surfaces, such as stainless steel surfaces. The composition includes at least one fluorine-containing silane compound, at least one phosphorus-containing silane compound, and at least one hydrolysable compound. This coating is suitable for condenser tubes, among other applications, to promote dropwise condensation.

  17. The Relationship of Culture Media Composition and Chemical Composition on Spirulina sp for Metal Ion Adsorbent

    Directory of Open Access Journals (Sweden)

    Hilda Zulkifli

    2016-12-01

    Full Text Available The analysis relationship of Spirulina sp medium with chemical composition has been conducted. Chemical analysis was performed using X-Ray Fluorescence analysis. Furthermore, potention of Spirulina sp as adsorbent of metal ions was analyzed using FTIR spectroscopy. The results showed that metals such as Zn, Fe, Mn, Ca, Cu, and Mo were mainly metals in Spirulina sp. These metals were not correlated with cultivated medium of Spirulina sp. Analysis of potention Spirulina sp as metal ions adsorbent showed that Spirulina sp has functional groups –C=O and –OH as ligand. Intercation of metal ions Cu(II and Cr(III with Spirulina sp indicated that metal ions bond to –C=O functional group.

  18. Wear Studies on Metal Matrix Composites: a Taguchi Approach

    Institute of Scientific and Technical Information of China (English)

    S. Basavarajappa; G. Chandramohan

    2005-01-01

    An attempt has been made to study the influence of wear parameters like applied load, sliding speed, sliding distance and percentage of reinforcement on the dry sliding wear of the metal matrix composites. A plan of experiments,based on techniques of Taguchi, was pedormed to acquire data in controlled way. An orthogonal array and the analysis of variance were employed to investigate the influence of process parameters on the wear of composites. The objective is to establish a correlation between dry sliding wear of composites and wear parameters. These correlations were obtained by multiple regressions. Finally, confirmation tests were conducted to verify the experimental results foreseen from the mentioned correlations.

  19. Preparation of Cu-based Bulk Metallic Glass Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    Yufeng SUN; Yuren WANG; Bingchen WEI; Weihuo LI

    2006-01-01

    Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) matrix composites containing in situ formed TiC particles and δ-TiCu dendrite phase were developed by copper mold cast. The thermal stability and microstructure of the composites are investigated. Room temperature compression tests reveal that the composite samples exhibit higher fracture strength and distinct plastic strain of 0.2%~0.5%, comparing with that of the corresponding Cu47Ti34Zr11 Ni8 monolithic BMG.

  20. Metal matrix composites: History, status, factors and future

    Science.gov (United States)

    Cyriac, Ajith James

    The history, status, and future of metal matrix composites are presented by evaluating the progression of available literature through time. The trends that existed and issues that still prevail are discussed and a prediction of the future for MMCs is presented. The factors that govern the performance of metal matrix composites are also discussed. In many developed countries and in several developing countries there exists continued interest in MMCs. Researchers tried numerous combinations of matrices and reinforcements since work strictly on MMCs began in the 1950s. This led to developments for aerospace and defense applications, but resultant commercial applications were limited. The introduction of ceramic whiskers as reinforcement and the development of 'in-situ' eutectics in the 1960s aided high temperature applications in aircraft engines. In the late 1970s the automobile industries started to take MMCs seriously. In the last 20 years, MMCs evolved from laboratories to a class of materials with numerous applications and commercial markets. After the collapse of the Berlin Wall, prevailing order in the world changed drastically. This effect was evident in the progression of metal matrix composites. The internet connected the world like never before and tremendous information was available for researchers around the world. Globalization and the internet resulted in the transformation of the world to a more level playing field, and this effect is evident in the nature and source of research on metal matrix composites happening around the world.

  1. Electroless synthesis of cellulose-metal aerogel composites

    Science.gov (United States)

    Schestakow, M.; Muench, F.; Reimuth, C.; Ratke, L.; Ensinger, W.

    2016-05-01

    An environmentally benign electroless plating procedure enables a dense coating of silver nanoparticles onto complex cellulose aerogel structures. In the course of the nanoparticle deposition, the morphological characteristics of the aerogel are preserved, such as the continuous self-supporting network structure. While achieving a high metal loading, the large specific surface area as well as the low density is retained in the cellulose-metal aerogel composite. Due to the interesting features of cellulose aerogel substrates (e.g., the accessibility of its open-porous network) and electroless plating (e.g., the possibility to control the density, size, and composition of the deposited metal nanoparticles), the outlined synthetic scheme provides a facile and flexible route towards advanced materials in heterogeneous catalysis, plasmonics, and sensing.

  2. Core-Shell and Segmented Polymer-Metal Composite Nanostructures

    Science.gov (United States)

    Lahav, Michal; Weiss, Emily; Xu, Qiaobing; Whitesides, George M.

    2008-01-01

    Composite nanostructures (~200 nm wide and several μm long) of metal and polyaniline (PANI) in two new variations of core-shell (PANI-Au) and segmented (Au-PANI and Ni-Au-PANI) architectures were fabricated electrochemically within anodized aluminum oxide (AAO) membranes. Control over the structure of these composites (including the length of the gold shells in the core-shell structures) was accomplished by adjusting the time and rate of electrodeposition, and the pH of the solution from which the materials were grown. Exposure of the core-shell structures to oxygen plasma removed the PANI and yielded aligned gold nanotubes. In the segmented structures, a self-assembled monolayer (SAM) of thioaniline nucleated the growth of PANI on top of metal nanorods, and acted as an adhesion layer between the metal and PANI components. PMID:16968046

  3. Fabrication of Ceramic Composites by Directed Metal Oxidation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-ya; TAN Yue-hua

    2004-01-01

    To explain the growth mechanism of Al2O3/Al Lanxide composites, the dynamics of the directedoxidation of Al-Mg-Si alloys are analyzed. The experimental methods to produce Lanxide composites by directedoxidation of metal melts at high temperatures are presented. The effect of the processing factors on the microstruc-tures and properties of Al2O3/Al composites and enforced Al2O3/Al composites is also analyzed. Compared withsintering ceramic composites, the advantages of Lanxide process and Lanxide materials are as following: it is a nearnet shaped process; the process is very simple; the microstructures and properties of Lanxide materials can be adjust-ed; and this process can be used to infiltrate ceramic fiber or particle preforms .

  4. Eigenmodes and field distribution of a nanosphere-in-a-nanoshell metallodielectric nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Manassah, Jamal T., E-mail: jmanassah@gmail.com [Department of Electrical Engineering, City College of New York, New York, NY 10031 (United States)

    2012-08-06

    I compute the plasmonic eigenmodes of a nanostructure consisting of a metallic sphere surrounded by a layer of dielectric C (d{sub C}) and a metallic shell on top embedded in a dielectric A (d{sub A}). Using the continuity conditions of the tangential components of the magnetic flux density and of the electric field at the interfaces and the Drude model, I obtain the equations relating the dominant three plasmonic eigenfrequencies and decay rates, to the nanostructure geometric parameters and the indices of refraction of d{sub A} and d{sub C}. I also compute the electric and magnetic fields' configurations for the dominant eigenmodes. -- Highlights: ► Compute the eigenmodes, resonance frequencies and decay rates, for a metallic nanosphere in a nanoshell. ► Full Maxwell treatment. No quasi-static approximation. ► Computationally direct and accurate. ► Method can be easily generalized to any multilayers spherical structure.

  5. Creating nanoshell on the surface of titanium hydride bead

    Directory of Open Access Journals (Sweden)

    PAVLENKO Vyacheslav Ivanovich

    2016-12-01

    Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

  6. Tunable optical properties of silver-dielectric-silver nanoshell

    Science.gov (United States)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2014-05-01

    Tunable optical properties of silver-dielectric-silver nanoshell including surface plasmon resonance (SPR) and resonance light scattering (RLS) based on quasi-static theory are investigated. When the silver core radius increases, the longer resonance wavelength red shifts and light scattering cross-section decreases whereas the shorter resonance wavelength blue shifts and the light scattering cross-section increases. The effect of middle dielectric thickness on the light scattering cross-section of nanoshell is different from those of the silver core radius changes. As middle dielectric radius increases, the longer resonance wavelength first blue shifts and then red shifts and the light scattering cross-section increases whereas the shorter resonance wavelength always red shifts and the light scattering cross-section decreases. The sensitivity of RLS to the refractive index of embedding medium is also reported. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness leads to increase the sensitivity of silver-dielectric-silver nanoshell. Tunable optical properties of silver-dielectric-silver nanoshell verify the biosensing potential of this nanostructure.

  7. Synthesis of agarose-metal/semiconductor nanoparticles having superior bacteriocidal activity and their simple conversion to metal-carbon composites

    Indian Academy of Sciences (India)

    K K R Datta; B Srinivasan; H Balaram; M Eswaramoorthy

    2008-11-01

    Agarose, a naturally occurring biopolymer is used for the stabilization of metal, semiconductor nanoparticles. Ag and Cu nanoparticles stabilized in agarose matrix show excellent antibacterial activity against E. coli bacteria. The well dispersed metal nanoparticles within the agarose composite films can be readily converted to carbon-metal composites of catalytic importance.

  8. A statistical model for sliding wear of metals in metal/composite systems

    Science.gov (United States)

    Wang, A.; Rack, H. J.

    1992-09-01

    The wear of a nominally harder single-phase metal sliding against a nominally softer metal-matrix composite containing a dispersion of hard second-phase reinforcement is described by a statistical wear model which considers the effects of local variations in hardness and microstructure on asperity interactions. It was shown theoretically that the wear rate of the unreinforced component varies exponentially with nominal reinforcement volume fraction. Model experiments performed on a SiC(w)-2124 Al composite/17-4 PH steel system confirmed the validity of the theory.

  9. Influence of Filler Metals in Welding Wires on the Phase and Chemical Composition of Weld Metal

    Science.gov (United States)

    Kozyrev, N. A.; Osetkovskiy, I. V.; Kozyreva, O. A.; Zernin, E. A.; Kartsev, D. S.

    2016-04-01

    The influence of filler metals used in welding wires on the phase and chemical composition of the metal, which is surfaced to mining equipment exposed to abrasive wear, has been investigated. Under a laboratory environment, samples of Mo-V-B and Cr-Mn-Mo-V wires were made. The performed experiments have revealed that fillers of the Cr-Mn-Mo-V system used in powder wire show better wear resistance of the weld metal than that of the Mn-Mo-V-B system; the absence of boron, which promotes grain refinement in the Mn-Mo-V-B system, significantly reduces wear resistance; the Mn-Mo-V-B weld metal has a finer structure than the Cr-Mn-Mo-V weld metal.

  10. A novel testbed structure for nanoshell based devices

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Mohammad A [Department of Electrical Engineering, Pennsylvania State University, University Park, Pittsburgh, PA (United States); Geiger, Richard T [Department of Electrical Engineering, Pennsylvania State University, University Park, Pittsburgh, PA (United States); Kim, Jaekyun [Department of Electrical Engineering, Pennsylvania State University, University Park, Pittsburgh, PA (United States)

    2007-06-27

    The design and the fabrication of a novel testbed for nanoshell based devices is reported. We have identified six criteria for an ideal resistive nanodevice and show that our testbed satisfies most of these criteria. We describe how the unique design of the testbed minimizes most of the resilient problems in the current nanodevices, like non-uniformity, assembly, stray nanocomponents and cost. We have tested the testbed by using gold nanoshell coated silica spheres as the active device element. We discuss the nature and the implications of the contact resistance between a flat electrode and a spherical nanoshell. We suggest various applications of the testbed, from nanofuses to ultrafast oxide sensors and to bio-sensors. We describe methods and steps for miniaturization of the testbed.

  11. Enhanced water droplet mobility on superhydrophobic rippled nanoshell array

    Science.gov (United States)

    Im, Hwon; Ji, Seungmuk; Moon, Dong-Il; Lim, Hyuneui; Choi, Yang-Kyu

    2016-10-01

    A 3-dimensional rippled nanoshell structure (a hollow pillar with wriggly sidewall morphology) is demonstrated for superhydrophobicity. As a control group, a straight nanoshell structure without a rippled shape was also prepared. The rippled structure showed improved superhydrophobicity with a large contact angle and a small sliding angle compared to the straight nanoshell structure. These enhancements originate from the minimum of interfacial energy at the triple-phase contact line, which is located at the most protruded circular line along the rippled structure. Using a drop impingement test, the stabilization of a Cassie Baxter state on the rippled structure was also verified. The experimental observation of wetting transition from a Cassie-Baxter to a Wenzel state is well explained by a revamped capillary pressure model, which was customized for the rippled structure.

  12. Near- and Far-Field Optical Response of Eccentric Nanoshells.

    Science.gov (United States)

    Peña-Rodríguez, Ovidio; Díaz-Núñez, Pablo; Rodríguez-Iglesias, Vladimir; Montaño-Priede, Luis; Rivera, Antonio; Pal, Umapada

    2017-12-01

    We study the optical response of eccentric nanoshells (i.e., spherical nanoparticles with an eccentric spherical inclusion) in the near and the far field through finite-difference time-domain simulations. Plasmon hybridization theory is used to explain the obtained results. The eccentricity generates a far-field optical spectrum with various plasmon peaks. The number, position, and width of the peaks depend on the core offset. Near-field enhancements in the surroundings of these structures are significantly larger than those obtained for equivalent concentric nanoshells and, more importantly, they are almost independent of the illumination conditions. This opens up the door for using eccentric nanoshells in applications requiring intense near-field enhancements.

  13. Wet-chemical synthesis and characteristics of Au nanoshell

    Institute of Scientific and Technical Information of China (English)

    LIU Zhongxin; SONG Hongwei; YU Lixin; YANG Linmei; PAN Guohui

    2005-01-01

    Gold nanoshells were prepared by an easy wet-chemical method, with Ag nanoparticles used as the templates. Transmission electron microscopy (TEM) indicated that the shells were sphere in shape, the size was homogenous, being about 20 nm, and no hard agglomerates were observed. The plasma resonance absorption of gold was tuned from visible to near-infrared (NIR) with the increased volume of HAuCl4. The temperature grads (ΔT) of the gold nanoshell hydrosol under the exposure of an 808-nm optical fiber laser with different power densities were measured. The highest ΔT was 30℃ (5 W/cm2, irradiation area was 2 cm2). This kind of gold nanoshell hydrosol is a promising material to be used in biomedicine such as photothermal cancer therapy, and its special photothermal convert property will photothermally trigger drug release.

  14. Nanoshell bioconjugates for integrated imaging and therapy of cancer

    Science.gov (United States)

    Loo, Christopher H.; Lee, Min-Ho; Hirsch, Leon R.; West, Jennifer L.; Halas, Naomi J.; Drezek, Rebekah A.

    2004-06-01

    Currently, separate diagnostic and therapeutic modalities are required for the diagnosis and treatment of cancer. In many cases, the present standard of care requires invasive surgical procedures and/or other treatments associated with significant side effect profiles, high cost, and poor clinical outcome. A single technology with dual diagnostic/therapeutic capabilities would potentially yield significant savings in the time and cost associated with diagnosing and treating many cancers. In this paper, we discuss gold nanoshell bioconjugates and their role in the development of an integrated cancer imaging and therapy application. Nanoshells are a novel class of nanomaterials that have unique properties including continuous and broad wavelength tunability, far greater scattering and absorption coefficients, increased chemical stability, and improved biocompatibility. Here, we describe the development of an integrated cancer imaging and therapy application using near-infrared (NIR) gold nanoshell bioconjugates.

  15. Damping behaviors of metal matrix composites with interface layer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel technique of designing the interface layer in metal matrix composites of high damping capacity was developed via different CVD coatings on carbon fibers in Cf/Al composites. It was shown that the interface layer improved the tensile strength, elastic modulus and damping capacity of the Cf/Al composites. A carbon layer showed the highest improvement and a silicon layer the lowest, while a mixed carbon and silicon layer exhibited an intermediate effect. Moreover, the thickness of interface layer also influences the damping capacity. A thicker carbon layer produced a better damping capacity because the dependence of damping capacity on strain amplitude was increased. It is suggested that a micro-sliding action occurring in the interface layer is the main mechanism responsible for the high damping capacity of the composites.

  16. Wear and Friction Behavior of Metal Impregnated Microporous Carbon Composites

    Science.gov (United States)

    Goller, Gultekin; Koty, D. P.; Tewari, S. N.; Singh, M.; Tekin, A.

    1996-01-01

    Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.

  17. Microstructure and strength of a deformation processed aluminum-20%tin metal-metal composite

    Science.gov (United States)

    Xu, Kai

    An Al-20vol.% Sn metal-metal composite was deformation processed by extrusion, swaging, and wire drawing to a total true strain of 7.4, resulting in a microstructure with Sn filaments in an Al matrix. Both the size and spacing of the Sn filaments decreased as deformation processing progressed. Immediately after deformation, the Sn second phase showed a convoluted, ribbon-shaped filamentary morphology, but the Sn filaments spheroidized during prolonged storage at room temperature. The driving force for spheroidization is chemical potential gradient due to curvature difference along Sn filaments. A critical wavelength of lambda crit = 2piR can be used to determine the spheroidization tendency of Sn cylinder. When lambda > 2piR, spheroidization is predicted to occur. The strength of these composites increased exponentially with the reduction in spacing of the Sn filaments. The relationship between UTS and deformation true strain is UTS = 72.6 exp(0.20eta). A Hall-Petch relationship between strength and filament spacing has been observed. Strengthening results from the filaments acting as barriers for dislocation motion. The primary shape instability modes are cylinderization of ribbons, boundary splitting, spheroidization of cylinders, and edge spheroidization of ribbons. The determining factors dictating which mechanism is active are grain boundary energy, interfacial energy, and ribbon cross section aspect ratio. The fiber texture was determined by orientation imaging microscopy to be for Al and for Sn. The 290 MPa ultimate tensile strength of the composite was greater than the rule-of-mixtures prediction. Comparisons are made with Al-Nb, Al-Ti and Al-Mg deformation processed metal metal composites and to various strengthening models for metal-metal composites.

  18. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  19. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  20. Tunable CD44-specific cellular retargeting with hyaluronic acid nanoshells

    DEFF Research Database (Denmark)

    Ebbesen, Morten F.; Olesen, Morten T. J.; Gjelstrup, Mikkel C.;

    2014-01-01

    Purpose In this work we specifically investigate the molecular weight (Mw) dependent combinatorial properties of hyaluronic acid (HA) for exhibiting stealth and targeting properties using different Mw HA nanoshells to tune nanoparticle retargeting to CD44-expressing cancer cells. Methods HA...... that indicates an extended and nonconstricted HA polymer surface. Reduced non-specific particle interaction in CD44- cells was shown for all HA nanoshells but CD44-dependent cellular retargeting and internalization in CD44+ cells was highly dependent on the coating HA Mw properties. Conclusion The combination...

  1. Charge dynamics in conducting polyaniline–metal oxalate composites

    Indian Academy of Sciences (India)

    R Murugesan; E Subramanian

    2003-08-01

    Polyaniline (Pani) and its metal oxalate composites (∼ 10 wt.%) of trivalent metal ions of Cr, Fe, Mn, Co and Al were synthesized by chemical oxidative polymerization technique with potassium perdisulphate oxidant in aqueous sulphuric acid medium. These materials were characterized by UV–VIS and EPR spectral techniques. Their d.c. electrical conductivities at room temperature and also as a function of temperature (307–453 K) were measured by four-probe technique. Presence of radical cation/polaron transition was indicated by UV–VIS absorption peak and EPR signals. Further, a close correlation existed between the conductivities and EPR parameters such as line width and peak ratio, which demonstrated that both mobile and fixed spins are involved in these composites. The dependence of conductivity on temperature, when analysed graphically by VRH, GB and TC mechanisms, pointed out that VRH is the predominant charge transport mechanism in these materials.

  2. Silver Nanoshell Plasmonically Controlled Emission of Semiconductor Quantum Dots in the Strong Coupling Regime.

    Science.gov (United States)

    Zhou, Ning; Yuan, Meng; Gao, Yuhan; Li, Dongsheng; Yang, Deren

    2016-04-26

    Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.

  3. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyong June [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  4. Catalytic Properties of AgPt Nanoshells as a Function of Size: Larger Outer Diameters Lead to Improved Performances.

    Science.gov (United States)

    Rodrigues, Thenner S; da Silva, Anderson G M; Gonçalves, Mariana C; Fajardo, Humberto V; Balzer, Rosana; Probst, Luiz F D; da Silva, Alisson H M; Assaf, Jose M; Camargo, Pedro H C

    2016-09-13

    We report herein a systematic investigation on the effect of the size of silver (Ag) nanoparticles employed as starting materials over the morphological features and catalytic performances of AgPt nanoshells produced by a combination of galvanic replacement between Ag and PtCl6(2-) and PtCl6(2-) reduction by hydroquinone. More specifically, we focused on Ag nanoparticles of four different sizes as starting materials, and found that the outer diameter, shell thickness, and the number of Pt surface atoms of the produced nanoshells increased with the size of the starting Ag nanoparticles. The produced AgPt nanoshells were supported into SiO2, and the catalytic performances of the AgPt/SiO2 nanocatalysts toward the gas-phase oxidation of benzene, toluene, and o-xylene (BTX oxidation) followed the order: AgPt 163 nm/SiO2 > AgPt 133 nm/SiO2 > AgPt 105 nm/SiO2 > AgPt 95 nm/SiO2. Interestingly, bigger AgPt nanoshell sizes lead to better catalytic performances in contrast to the intuitive prediction that particles having larger outer diameters tend to present poorer catalytic activities due to their lower surface to volume ratios as compared to smaller particles. This is in agreement with the H2 chemisorption results, and can be assigned to the increase in the Pt surface area with size due to the presence of smaller NPs islands at the surface of the nanoshells having larger outer diameters. This result indicates that, in addition to the overall diameters, the optimization of the surface morphology may play an important role over the optimization of catalytic activities in metal-based nanocatalysts, which can be even more pronounced that the size effect. Our data demonstrate that the control over surface morphology play a very important role relative to the effect of size to the optimization of catalytic performances in catalysts based on noble-metal nanostructures.

  5. Introduction to bulk metallic glass composite and its recent applications

    OpenAIRE

    2011-01-01

    Bulk metallic glass (BMG) materials are hot topics in recent years, not to mention BMG matrix composites, which further improve the magnetic and mechanical properties of BMG materials. BMG and BMG matrix materials are fast developing and promising materials in modern industry due to their extraordinary properties such as high strength, low density, excellent resistibility to high temperature and corrosion. In this paper, I reviewed processing and application of several recently developed BMG ...

  6. Nanoporous Polymer-Ceramic Composite Electrolytes for Lithium Metal Batteries

    KAUST Repository

    Tu, Zhengyuan

    2013-09-16

    A nanoporous composite material that offers the unique combination of high room-temperature ionic conductivity and high mechanical modulus is reported. When used as the separator/electrolyte in lithium batteries employing metallic lithium as anode, the material displays unprecedented cycling stability and excellent ability to prevent premature cell failure by dendrite-induced short circuits © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Active Metal Brazing of Carbon-Carbon Composites to Titanium

    Science.gov (United States)

    Singh, M.; Shpargel, T. P.; Morscher, G.; Asthana, R.

    2004-01-01

    The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSil. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint which led to good wetting, spreading, and metallurgical bond formation via interdiffusion.

  8. Energy Absorption Characteristics of Metallic and Composite Shells

    Directory of Open Access Journals (Sweden)

    R. Velmurugan

    2003-04-01

    Full Text Available Metallic and composite shells of different sizes and tubes were subjected to axial compression in an Instron Machine. Their progressive failure modes and energy absorption capacities have been studied. In the case of metallic shells, analytical expressions are derived to find the mean collapse load and the fold length based on the formation of plastic hinges. Theoretical results have been compared with experimental results wherever possible. The effect of internal folding on the post-collapse behaviour of round tubes has been discussed and expressions for fold length and post-collapse load compression curves are derived as a function of internal folding. Based on the experimental observations, analysis has been carried out to find the progressive crushing load and crush length in a cycle of round and conical shells. The shells are infilled with polyurethane foam and subjected to axial compression. The effect of foam on the crushing behaviour is also studied. Conical shells of different cone angles varied from 8.5" to 45" and the effect of cone angle on the crushing mode of the conical shells has been studied. Also, a comparative study of metallic and composite shells has been carried out based on the deformation and energy absorption characteristics. The different parameters considered for analysis include effective crushing length and total energy absorbed during the crushing process and the Euler buckling length in metallic shells.

  9. A Study of Metal-Cement Composites with Additives

    Directory of Open Access Journals (Sweden)

    Mironov Victor

    2014-12-01

    Full Text Available The application of small-sized metal fillers (SMF provides a combination of high bulk density, increased durability and ferromagnetic properties of composite materials on the cement basis. However, the total strength of the composite can be compromised by poor adhesion of metal particles with the cement matrix. The use of versatile additives like microsilica and metakaolin is able to improve the structural integrity and mechanical properties of heavy concretes. The paper considers the results of a study using specimens of heavy concretes with SMF aiming to estimate its strength, structural features and ultrasonic parameters. It was found that the contact of SMF particles with the cement was not perfect, since the voids appeared between them and the cement matrix during the cement hydration process (exothermal reaction. Due to the border porosity, the specimens with the metal fillers have lower compressive strength, lower ultrasound velocity and increased frequency slope of attenuation. Microsilica and metakaolin additives facilitate better contact zone between the cement matrix and metal fillers.

  10. Analysis of Surface Integrity in Drilling Metal Matrix and Hybrid Metal Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    T. Rajmohan; K. Palanikumar; J. Paulo Davim

    2012-01-01

    Hybrid metal matrix composites consist of at least three constituents-a metal or an alloy matrix and two reinforcements in various forms, bonded together at the atomic level in the composite. Despite their higher specific properties of strength and stiffness, the non homogeneous and anisotropic nature combined with the abrasive reinforcements render their machining difficult. In this paper, the surface integrity of machining in drilling hybrid composites has been discussed. Drilling tests are carried out at different spindle speed, feed rates, and different drill tool materials to investigate the effect of the various cutting parameters on the surface quality and the extent of the deformation of drilled surface due to drilling. Materials used for the present investigation are A1356/IOSIC (wt%) metal matrix and A1356/10SiC-3mica (wt%) hybrid composites. The composites are fabricated using stir casting route. The drilling tests are conducted on vertical computer numeric control (CNC) machining center using carbide, coated carbide and polycrystalline diamond (PCD) drills. The surface roughness decreases with increasing spindle speed and increases with increasing feed rate. The machined surface is analyzed by scanning electron microscopy (SEM). SEM images of the machined surfaces indicate the presence of grooves and pits. Microhardness depth profiles indicate that the subsurface damage is limited to the top of 100-250 μm.

  11. Metal matrix composites synthesis, wear characteristics, machinability study of MMC brake drum

    CERN Document Server

    Natarajan, Nanjappan; Davim, J Paulo

    2015-01-01

    This book is dedicated to composite materials, presenting different synthesis processes, composite properties and their machining behaviour. The book describes also the problems on manufacturing of metal matrix composite components. Among others, it provides procedures for manufacturing of metal matrix composites and case studies.

  12. Modeling transport properties of inhomogeneous superconductor-metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Borroto, A.; Altshuler, E., E-mail: ealtshuler@fisica.uh.cu [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Del Río, L. [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Physics Department, McGill University, Montreal, Quebec H3A 2T8 (Canada); Arronte, M. [BRALAX, S. de RL., Tampico, Tamaulipas (Mexico); Technological Laser Laboratory, IMRE, University of Havana, 10400 Havana (Cuba); Johansen, T. H. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2014-11-17

    We propose a model for a superconductor-metal composite that allows to derive intrinsic transport properties of the superconducting phase based on 2D images of its cross section, and a minimal set of parameters. The method is tested experimentally by using, as model composite, a “transversal bridge” made on a Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} (BSCCO)-Ag multi-filamentary tape. It is shown that the approach allows to predict the measured I−〈E〉 curves of the filaments. In addition, one can determine the critical current anisotropy between the longitudinal and transverse directions of the Ag-BSCCO tape, and also of its superconducting filaments separately, which emphasizes the role of the morphology of the composite in the transport properties.

  13. Isothermal and nonisothermal fatigue behavior of a metal matrix composite

    Science.gov (United States)

    Gabb, T. P.; Gayda, J.; Mackay, R. A.

    1990-01-01

    The isothermal and nonisothermal fatigue resistance of a metal matrix composite (MMC) consisting of Ti-15V-3Cr-3Al-3Sn (Ti-15-3) matrix reinforced by 33 vol pct continuous SiC fibers was investigated. The fibers were nominally oriented parallel to the specimen axis. Isothermal fatigue tests were performed in air at 300 and 550 C. The MMC had good isothermal fatigue resistance at low cyclic stress, with fatigue cracks initiating from fiber-matrix interfaces and foil laminations. At high cyclic stresses, stress relaxation in the matrix reduced isothermal composite fatigue resistance at 550 C. Nonisothermal fatigue loading substantially degraded composite fatigue resistnce. This degradation was produced by a thermomechanical fatigue damage mechanism associated with the fiber-matrix interfaces.

  14. Metal/Graphitic Carbon Nitride Composites: Synthesis, Structures, and Applications.

    Science.gov (United States)

    Wang, Luona; Wang, Chengyin; Hu, Xiaoya; Xue, Huaiguo; Pang, Huan

    2016-12-06

    Graphitic carbon nitride (g-C3 N4 ) has been widely used in fields related to energy and materials science. However, nanostructured g-C3 N4 photocatalysts synthesized by traditional thermal polycondensation methods have the disadvantage of small specific surface areas and wide band gaps; these limit the catalytic activity and application range of g-C3 N4 . Based on the unique nanostructure of g-C3 N4 , it is a feasible method to modify g-C3 N4 with metals to design novel metal-semiconductor composites. Metals alter the photochemical properties of g-C3 N4 , in particular, narrow the band gap and expand photoabsorption into the visible range, which improves the photocatalytic performance. This review covers recent progress in metal/g-C3 N4 nanocomposites for photocatalysts, organic systems, biosensors, and so on. The aim is to summarize the synthetic methods, nanostructures, and applications of metal/g-C3 N4 nanocomposite materials, as well as discuss future research directions in these areas. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Prediction of high temperature metal matrix composite ply properties

    Science.gov (United States)

    Caruso, J. J.; Chamis, C. C.

    1988-01-01

    The application of the finite element method (superelement technique) in conjunction with basic concepts from mechanics of materials theory is demonstrated to predict the thermomechanical behavior of high temperature metal matrix composites (HTMMC). The simulated behavior is used as a basis to establish characteristic properties of a unidirectional composite idealized an as equivalent homogeneous material. The ply properties predicted include: thermal properties (thermal conductivities and thermal expansion coefficients) and mechanical properties (moduli and Poisson's ratio). These properties are compared with those predicted by a simplified, analytical composite micromechanics model. The predictive capabilities of the finite element method and the simplified model are illustrated through the simulation of the thermomechanical behavior of a P100-graphite/copper unidirectional composite at room temperature and near matrix melting temperature. The advantage of the finite element analysis approach is its ability to more precisely represent the composite local geometry and hence capture the subtle effects that are dependent on this. The closed form micromechanics model does a good job at representing the average behavior of the constituents to predict composite behavior.

  16. Color Doppler ultrasound and gamma imaging of intratumorally injected 500 nm iron-silica nanoshells.

    Science.gov (United States)

    Liberman, Alexander; Wu, Zhe; Barback, Christopher V; Viveros, Robert; Blair, Sarah L; Ellies, Lesley G; Vera, David R; Mattrey, Robert F; Kummel, Andrew C; Trogler, William C

    2013-07-23

    Perfluoropentane gas filled iron-silica nanoshells have been developed as stationary ultrasound contrast agents for marking tumors to guide surgical resection. It is critical to establish their long-term imaging efficacy, as well as biodistribution. This work shows that 500 nm Fe-SiO2 nanoshells can be imaged by color Doppler ultrasound over the course of 10 days in Py8119 tumor bearing mice. The 500 nm nonbiodegradable SiO2 and biodegradable Fe-SiO2 nanoshells were functionalized with diethylenetriamine pentaacetic acid (DTPA) ligand and radiolabeled with (111)In(3+) for biodistribution studies in nu/nu mice. The majority of radioactivity was detected in the liver and kidneys following intravenous (IV) administration of nanoshells to healthy animals. By contrast, after nanoshells were injected intratumorally, most of the radioactivity remained at the injection site; however, some nanoshells escaped into circulation and were distributed similarly as those given intravenously. For intratumoral delivery of nanoshells and IV delivery to healthy animals, little difference was seen between the biodistribution of SiO2 and biodegradable Fe-SiO2 nanoshells. However, when nanoshells were administered IV to tumor bearing mice, a significant increase was observed in liver accumulation of SiO2 nanoshells relative to biodegradable Fe-SiO2 nanoshells. Both SiO2 and Fe-SiO2 nanoshells accumulate passively in proportion to tumor mass, during intravenous delivery of nanoshells. This is the first report of the biodistribution following intratumoral injection of any biodegradable silica particle, as well as the first report demonstrating the utility of DTPA-(111)In labeling for studying silica nanoparticle biodistributions.

  17. Formation and Stability of Hollow MgO Nanoshells

    NARCIS (Netherlands)

    Krishnan, G.; Palasantzas, G.; Kooi, B.J.

    2010-01-01

    High temperature annealing of gas phase synthesized Mg nanoparticles surrounded by an MgO shell leads to formation of hollow MgO nanoshells due to the evaporation assisted Kirkendall effect. Under electron beam exposure in TEM, the (220) MgO facets reduce their high surface energy by forming cube fa

  18. Using gold nanorods and nanoshells in photothermal cancer therapy

    Science.gov (United States)

    Nhung, Tran; Duong, Vu; Tracy, Dustin; Drosdoff, David; Woods, Lilia; Nguyen, Huong; Nga, Do; Viet, N. A.; Phan, Anh

    2014-03-01

    The ability of strongly absorbing near-infrared radiation and efficiently scattering photon energy of gold nanoshells and nanorods has been investigated for cancer treatments. The nanostructures sizes are chosen to achieve a surface plasmon resonance localized peak in the ``human-being skin windows'' (650-900 nm), which is the best possible regime of operation for cancer treatment. After injecting nanoshell and nanorod solutions into chicken tissues, variations of temperature of samples as a function of time with and without near-infrared-light irradiation at 808 nm are reported. The temperature of chicken tissues injected with nanorods is found to be greater than that of the samples with nanoshells for the same absorbance of nanomaterials. The photothermal transduction efficiency of nanorods is also proved to be higher than that of nanoshells. Our theoretical calculations show excellent agreement with the experimental data. This work was supported by the Nafosted Grant No. 103.01-2013.25 and 103.06.101.09. THN is partially supported by USDA NIFA grant 2013-67017-21221. L.M.W. acknowledges support from the Department of Energy under contract DE-FG02-06ER46297.

  19. Gold nanoparticles having dipicolinic acid imprinted nanoshell for Bacillus cereus spores recognition

    Energy Technology Data Exchange (ETDEWEB)

    Gueltekin, Aytac [Department of Chemistry, Trakya University, Edirne (Turkey); Ersoez, Arzu; Huer, Deniz [Department of Chemistry, Anadolu University, Eskisehir (Turkey); Sarioezlue, Nalan Yilmaz [Department of Biology, Anadolu University, Eskisehir (Turkey); Denizli, Adil [Department of Chemistry, Hacettepe University, Ankara (Turkey); Say, Ridvan, E-mail: rsay@anadolu.edu.tr [Department of Chemistry, Anadolu University, Eskisehir (Turkey); BIBAM (Plant, Drug and Scientific Research Center) Anadolu University (Turkey)

    2009-10-15

    Taking into account the recognition element for sensors linked to molecular imprinted polymers (MIPs), a proliferation of interest has been witnessed by those who are interested in this subject. Indeed, MIP nanoparticles are theme which recently has come to light in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamidocysteine (MAC) attached to gold nanoparticles, reminiscent of a self-assembled monolayer. Furthermore, a surface shell by synthetic host polymers based on molecular imprinting method for recognition has been reconstructed. In this method, methacryloyl iminodiacetic acid-chrome (MAIDA-Cr(III)) has been used as a new metal-chelating monomer via metal coordination-chelation interactions and dipicolinic acid (DPA) which is the main participant of Bacillus cereus spores has been used as a template. Nanoshell sensors with templates produce a cavity that is selective for DPA. The DPA can simultaneously chelate to Cr(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Cr(III) ion and free coordination spheres has an effect on the binding ability of the gold nanoparticles nanosensor. The interactions between DPA and MIP particles were studied observing fluorescence measurements. DPA addition caused significant decreases in fluorescence intensity because they induced photoluminescence emission from Au nanoparticles through the specific binding to the recognition sites of the crosslinked nanoshell polymer matrix. The binding affinity of the DPA imprinted nanoparticles has been explored by using the Langmuir and Scatchard methods and the analysis of the quenching results has been performed in terms of the Stern-Volmer equation.

  20. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    Energy Technology Data Exchange (ETDEWEB)

    Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A.; Brown, Gilbert M.

    2017-04-11

    Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions include microspheres with an average diameter between about 200 nanometers and about 10 micrometers and mesopores on the surface and interior of the microspheres. The methods of making include forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least annealing in a reducing atmosphere, doping with an aliovalent element, and coating with a coating composition.

  1. Metal-organic framework composites: from fundamentals to applications

    Science.gov (United States)

    Li, Shaozhou; Huo, Fengwei

    2015-04-01

    Metal-organic frameworks (MOFs) are a class of crystallized porous polymeric materials consisting of metal ions or clusters linked together by organic bridging ligands. Due to their permanent porosity, rich surface chemistry and tuneable pore sizes, MOFs have emerged as one type of important porous solid and have attracted intensive interests in catalysis, gas adsorption, separation and storage over the past two decades. When compared with pure MOFs, the combination of MOFs with functional species or matrix materials not only shows enhanced properties, but also broadens the applications of MOFs in new fields, such as bio-imaging, drug delivery and electrical catalysis, owing to the interactions of the functional species/matrix with the MOF structures. Although the synthesis, chemical modification and potential applications of MOFs have been reviewed previously, there is an increasing awareness on the synthesis and applications of their composites, which have rarely been reviewed. This review aims to fill this gap and discuss the fabrication, properties, and applications of MOF composites. The remaining challenges and future opportunities in this field, in terms of processing techniques, maximizing composite properties, and prospects for applications, have also been indicated.

  2. Ultrafine-grained Aluminm and Boron Carbide Metal Matrix Composites

    Science.gov (United States)

    Vogt, Rustin

    Cryomilling is a processing technique used to generate homogenously distributed boron carbide (B4C) particulate reinforcement within an ultrafine-grained aluminum matrix. The motivation behind characterizing a composite consisting of cryomilled aluminum B4C metal matrix composite is to design and develop a high-strength, lightweight aluminum composite for structural and high strain rate applications. Cryomilled Al 5083 and B4C powders were synthesized into bulk composite by various thermomechanical processing methods to form plate and extruded geometries. The effects of processing method on microstructure and mechanical behavior for the final consolidated composite were investigated. Cryomilling for extended periods of time in liquid nitrogen has shown to increase strength and thermal stability. The effects associated with cryomilling with stearic acid additions (as a process-control agent) on the degassing behavior of Al powders is investigated and results show that the liberation of compounds associated with stearic acid were suppressed in cryomilled Al powders. The effect of thermal expansion mismatch strain on strengthening due to geometrically necessary dislocations resulting from quenching is investigated and found not to occur in bulk cryomilled Al 5083 and B 4C composites. Previous cryomilled Al 5083 and B4C composites have exhibited ultrahigh strength associated with considerable strain-to-failure (>14 pct.) at high strain rates (>103/s) during mechanical testing, but only limited strain-to-failure (˜0.75 pct.) at quasi-static strain rates (10-3/s). The increased strain to failure at high strain rates is attributed to micro-flaw developments, including kinking, extensive axial splitting, and grain growth were observed after high strain rate deformation, and the significance of these mechanisms is considered.

  3. Metal-nanotube composites as radiation resistant materials

    Energy Technology Data Exchange (ETDEWEB)

    González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, CEDENNA, Universidad de Chile, Casilla 653, Santiago 7800024 (Chile); Duin, Adri C. T. van [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); So, Kang Pyo; Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bringa, Eduardo M. [CONICET and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza 5500 (Argentina)

    2016-07-18

    The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

  4. Metal Alloy Compositions And Process Background Of The Invention

    Science.gov (United States)

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  5. Review on Fabrication Methods of in situ Metal Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper deals with a series of novel processing techniques based on the in situ production of metal matrix composites (MMCs). In situ techniques involve a chemical reaction resulting in the formation of a very fine and thermodynamically stable reinforcing ceramic phase within a metal matrix. As a result, this provides thermodynamic compatibility at the matrix-reinforcement interface. The reinforcement surfaces are also likely to be free of contamination and, therefore, a stronger matrix-dispersion bond can be achieved. Some of these technologies including DIMOXTM, XD, PRIMEXTM, reactive gas infiltration, high-temperature self-propagating synthesis (SHS), and liquid-solid, or solid-gas-liquid reactions as well as plasma in situ MMCs are expressed in this paper.

  6. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    Science.gov (United States)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  7. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  8. Numerical analysis on thermal drilling of aluminum metal matrix composite

    Science.gov (United States)

    Hynes, N. Rajesh Jesudoss; Maheshwaran, M. V.

    2016-05-01

    The work-material deformation is very large and both the tool and workpiece temperatures are high in thermal drilling. Modeling is a necessary tool to understand the material flow, temperatures, stress, and strains, which are difficult to measure experimentally during thermal drilling. The numerical analysis of thermal drilling process of aluminum metal matrix composite has been done in the present work. In this analysis the heat flux of different stages is calculated. The calculated heat flux is applied on the surface of work piece and thermal distribution is predicted in different stages during the thermal drilling process.

  9. Internal friction in a new kind of metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    San Juan, J. [Dpt. Fisica Materia Condensada, Universidad del Pais Vasco, Facultad de Ciencia y Tecnologia, Apdo. 644-48080, Bilbao (Spain) and Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Facultad de Ciencia y Tecnologia, Apdo. 644-48080, Bilbao (Spain)]. E-mail: jose.sanjuan@ehu.es; No, M.L. [Dpt. Fisica Aplicada II, Universidad del Pais Vasco, Facultad de Ciencia y Tecnologia, Apdo. 644-48080, Bilbao (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Facultad de Ciencia y Tecnologia, Apdo. 644-48080, Bilbao (Spain)

    2006-12-20

    We have developed a new kind of metal matrix composites, based on powders of Cu-Al-Ni shape memory alloys (SMAs) surrounded by an indium matrix, specifically designed to exhibit high mechanical damping. The damping properties have been characterized by mechanical spectroscopy as a function of temperature between 150 and 400 K, frequency between 3 x 10{sup -3} and 3 Hz, and strain amplitude between 5 x 10{sup -6} and 10{sup -4}. The material exhibits, in some range of temperature, internal friction as high as 0.54. The extremely high damping is discussed in the light of the microstructure of the material, which has been characterized in parallel.

  10. Mechanical behaviour of engineering materials. Metals, ceramics, polymers, and composites

    Energy Technology Data Exchange (ETDEWEB)

    Roesler, Joachim; Baeker, Martin [TU Braunschweig (Germany). Inst. fuer Werkstoffe; Harders, Harald

    2007-07-01

    How do engineering materials deform when bearing mechanical loads? To answer this crucial question, the book bridges the gap between continuum mechanics and materials science. The different kinds of material deformation (elasticity, plasticity, fracture, creep, fatigue) are explained in detail. The book also discusses the physical processes occurring during the deformation of all classes of engineering materials (metals, ceramics, polymers, and composites) and shows how these materials can be strengthened to meet the design requirements. It provides the knowledge needed in selecting the appropriate engineering material for a certain design problem.

  11. Nanoporous metal organic frameworks as hybrid polymer-metal composites for drug delivery and biomedical applications.

    Science.gov (United States)

    Beg, Sarwar; Rahman, Mahfoozur; Jain, Atul; Saini, Sumant; Midoux, Patrick; Pichon, Chantal; Ahmad, Farhan Jalees; Akhter, Sohail

    2017-04-01

    Metal organic frameworks (MOFs), porous hybrid polymer-metal composites at the nanoscale, are recent innovations in the field of chemistry; they are novel polymeric materials with diverse biomedical applications. MOFs are nanoporous materials, consisting of metal ions linked together by organic bridging ligands. The unique physical and chemical characteristics of MOFs have attracted wider attention from the scientific community, exploring their utility in the field of material science, biology, nanotechnology and drug delivery. The practical feasibility of MOFs is possible owing to their abilities for biodegradability, excellent porosity, high loading capacity, ease of surface modification, among others. In this regard, this review provides an account of various types of MOFs, their physiochemical characteristics and use in diverse disciplines of biomedical sciences - with special emphasis on drug delivery and theranostics. Moreover, this review also highlights the stability and toxicity issues of MOFs, along with their market potential for biomedical applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Nanoshell-based substrates for surface enhanced spectroscopic detection of biomolecules.

    Science.gov (United States)

    Levin, Carly S; Kundu, Janardan; Barhoumi, Aoune; Halas, Naomi J

    2009-09-01

    Nanoshells are optically tunable core-shell nanostructures with demonstrated uses in surface enhanced spectroscopies. Based on their ability to support surface plasmons, which give rise to strongly enhanced electromagnetic fields at their surface, nanoshells provide simple, scalable, high-quality substrates. In this article, we outline the development and use of nanoshell-based substrates for direct, spectroscopic detection of biomolecules. Recent advances in the use of these nanostructures lead to improved spectroscopic quality, selectivity, and reproducibility.

  13. Theoretical Analysis the Optical Properties of Multi-coupled Silver Nanoshell Particles

    OpenAIRE

    Ma, Ye-Wan; Zhang, Jie; Zhang, Li-hua; Jian, Guo-Shu; Wu, Shi-Fa

    2011-01-01

    The surface plasmon resonances of silver nanoshell particles are studied by Green’s function. The nanoshell system of plasmon resonances results from the coupling of the inner and outer shell surface plasmon. The shift of the nanoshell plasmon resonances wavelength is plotted against with different dielectric environments, several different dielectric cores, the ratio of the inner and outer radius, and also its assemblies. The results show that a red- and blue-shifted localized surface plasmo...

  14. Long-wave approximation for hybridization modeling of local surface plasmonic resonance in nanoshells.

    Science.gov (United States)

    Li, Ben Q; Liu, Changhong

    2011-01-15

    A hybridization model for the localized surface plasmon resonance of a nanoshell is developed within the framework of long-wave approximation. Compared with the existing hybridization model derived from the hydrodynamic simulation of free electron gas, this approach is much simpler and gives identical results for a concentric nanoshell. Also, with this approach, the limitations associated with the original hybridization model are succinctly stated. Extension of this approach to hybridization modeling of more complicated structures such as multiplayered nanoshells is straightforward.

  15. In-vivo photoacoustic microscopy of nanoshell extravasation from solid tumor vasculature

    OpenAIRE

    Li, Meng-Lin; Wang, James Chunjay; Schwartz, Jon A.; Gill-Sharp, Kelly L.; Stoica, George; Lihong V. Wang

    2009-01-01

    In this study, high resolution backward-mode photoacoustic microscopy (PAM) is used to noninvasively image progressive extravasation and accumulation of nanoshells within a solid tumor in vivo. PAM takes advantage of the strong near-infrared absorption of nanoshells and their extravasation tendency from leaky tumor vasculatures for imaging. Subcutaneous tumors are grown on immunocompetent BALB/c mice. Polyethylene glycol (PEGylated) nanoshells with a peak optical absorption at ∼800nm are intr...

  16. Wear of semi-solid rheocast SiCp/Al metal matrix composites

    CSIR Research Space (South Africa)

    Curle, UA

    2010-09-01

    Full Text Available casting of SiC metal matrix composites. The metal matrix consisting of nearly spherical proeutectic a(Al) globules was produced. Spheroidization of fibrous eutectic silicon took place upon heat treatment of the as-cast metal matrix composites (MMCs...

  17. Nonlinear optical properties of metal nanoparticle composites for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y. E-mail: takeda.yoshihiko@nims.go.jp; Kishimoto, N

    2003-05-01

    Optical absorption and nonlinear optical response were investigated for nanoparticle composites in amorphous SiO{sub 2} fabricated by negative Ta ion implantation at 60 keV. X-ray photoelectron spectroscopy was used to identify Ta and the oxide formation in the matrix. Optical absorption clearly indicated a surface plasmon peak at 2.2 eV and the peak resulted from formation of nanoparticles embedded in the matrix. The measured absorption was compared with calculated ones, evaluated by Maxwell-Garnett theory. Nonlinear absorption was measured with a pump-probe method using a femtosecond laser system. The pumping laser transiently bleached the surface plasmon band and lead to the nonlinearity. The transient response recovered in several picoseconds and behaved in terms of electron dynamics in metallic nanoparticles. The Ta nanoparticle composite is one of the promising candidates for nonlinear optical materials with good thermal stability.

  18. High temperature fatigue of metal matrix composite for automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Marie-Louise, A.; Koster, A.; Remy, L. [Centre des Materiaux, PM. Fourt, Ecole Nationale Superieure des Mines de Paris, UMR CNRS 763, Evry (France); Bourgeois, M.; Martin-Borret, S. [PSA, Peugeot Citroeen, Direction de la Recherche et de l' Innovation Automobile, Velizy-Villacoublay (France)

    2004-07-01

    The high temperature low cycle fatigue (LCF) of metal-matrix composite (A356 with alumina reinforcement) was investigated. LCF tests interrupted and conducted up to failure were performed. Firstly, the effect of process defects and volume fraction of alumina was investigated for this composite. Then, damage accumulation was reported: an interrupted test procedure was used with a plastic replication technique. According to crack growth, the end of the LCF test is associated with a critical crack length equal to about 2 mm. Furthermore, an original crack growth LCF test was made using a specimen with three through notches at different locations. The effect of notch location was estimated. TOMKINS' model has finally been modified to predict the LCF crack growth and the life of smooth specimens. (orig.)

  19. Influence of metal-ceramic interfaces on the behaviour of metal matrix composites and their joints

    Energy Technology Data Exchange (ETDEWEB)

    Urena, A. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas; Gomez de Salazar, J.M. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas; Escalera, M.D. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas

    1997-06-01

    The present contribution emphasises the importance of the chemical reactions which occur during the fabrication and joining procedures, in the metallic matrix/ceramic reinforcement interfaces of the metal matrix composites. Using both the experimental data obtained by other investigators studding metal/ceramic systems such us Al/SiC, Al-Mg/Al{sub 2}O{sub 3}, Ti/SiC, etc.; and the results of the research carried out for the present authors in the diffusion bonding of Al/SiC and Al-Mg/Al{sub 2}O{sub 3} composites, the nature of these chemical reactions and their influence on the MMC properties are discussed. Authors also study the particularly case of the participation of Li in the interface reactions occurred in the Al/SiC system. For it, the data obtained in the study of the diffusion bonding of an aluminium-copper alloy (AA2124) reinforced with SiC whiskers and using an aluminium-lithium alloy (AA8090) as interlayer, are used. TEM observations showed that Li might change the nature of this interface and penetrate in the SiC lattice. It can answer to the increase in interface strength detected by other authors in Al-Li/SiC composites. The application of TEM has proved to be an essential tool for characterisation of these kind of interfaces. (orig.)

  20. Anisotropic magnetostrictive metal-polymer composites for functional devices

    Science.gov (United States)

    Kiseleva, T. Yu.; Zholudev, S. I.; Il'inykh, I. A.; Novakova, A. A.

    2013-12-01

    New metal-polymer composites based on mechanochemically synthesized magnetostrictive Fe-Ga phase particles with dimensions of up to 2 μm dispersed and spatially oriented in a polymer matrix have been studied. The polymer matrix for spatial anisotropic stabilization of particles was represented by modified polyurethane (PU). An increase in the magnetostrictive effect was achieved by directed orientation of particles in a magnetic field applied during polymerization of the PU matrix. The spatial anisotropy of the composite has been studied by the methods of conversion Mössbauer spectroscopy with resonant X-ray detection and scanning electron microscopy. It is shown that the mechanochemical synthesis is an effective method of obtaining particles with microstress-enhanced magnetostriction. The use of these particles for the formation of a functional elastomer composite provides a material with significant magnetostrictive effect, which can be several-fold increased due to orientation of particles in an applied magnetic field. The obtained anisotropic magnetostrictive composite is a promising material for the creation of smart functional components of positioning systems, attenuators, and sensors.

  1. Composite rebonding to stainless steel metal using different bonding agents.

    Science.gov (United States)

    al-Shalan, T A; Till, M J; Feigal, R J

    1997-01-01

    The purpose of this study was to determine the in vitro bond strengths of composite rebonded to stainless steel crown metal (SS) using five different bonding agents after composite to SS bond failure had been produced. The adhesive systems were applied to the failed bonds following the manufacturers' instructions and, as a control, composite was bonded to SS without using a bonding agent. Each group was then divided into two subgroups: mechanically prepared (MP), in which the SS was roughened by a diamond bur, and unprepared (NMP), in which no modification of the SS was done. ESPE VISIO-GEM composite was placed in a plastic mold and light cured to the treated SS. Samples were stored in water at 37 degrees C for 72 hr, thermocycled for 500 cycles between 5 and 55 degrees C, and mounted in an Instron Universal Testing Machine. Caulk's Adhesive System provided significantly higher rebond strength (228.97 +/- 106.9 kg/cm2) than the other materials, and mechanical surface preparation offered no significant advantages.

  2. Ultrahigh strength and ductility of metallic nanolayered composites

    Energy Technology Data Exchange (ETDEWEB)

    Mara, Nathan Allan [Los Alamos National Laboratory; Bhattacharyya, Dhriti [Los Alamos National Laboratory; Dickerson, Pat [Los Alamos National Laboratory; Hoagland, Richard [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory

    2009-01-01

    In recent years, the high strength of nanomaterials has gathered much interest in the materials community. Nanomaterials (polycrystalline and composites) have already been used, largely by the semiconductor community, as critical length scales for chip design have decreased to tens of nanometers. However, to ensure reliability of nanomaterials in almost any application, the mechanisms underlying their structural integrity must be well understood. For these materials to be put into service on a broader scale, not only should their strength be considered, but also ductility, toughness, formability, and fatigue resistance. While some progress has been made into constructing models for the deformation mechanisms governing these behaviors, the body of experimental knowledge is still limited, especially when length scales drop below 10 nanometers. This work produces stress-strain curves for nanolaminate composites with individual layer thickness of 40 nm and 5 run. Nanolaminate composites fabricated via magnetron sputtering comprised of alternating 5 nm thick Cu and Nb multilayers (two relatively soft metals) exhibit strengths on par with hardened tool steel and deformability in compression in excess of 25% [1]. The deformability of nanoscale composites is found to be limited by the onset of geometric instability, rather than due to intrinsic material behavior.

  3. Bioreducible cross-linked nanoshell enhances gene transfection of polycation/DNA polyplex in vivo.

    Science.gov (United States)

    Piao, Ji-Gang; Ding, Sheng-Gang; Yang, Lu; Hong, Chun-Yan; You, Ye-Zi

    2014-08-11

    In this study, we have prepared a self-cross-linking PEG-based branched polymer, which easily forms a bioreducible nanoshell around polyplexes of cationic polymer and DNA, simply via heating the polyplex dispersions in the presence of this self-cross-linking branched polymer. This nanoshell can prevent the polyplex from dissociation and aggregation in physiological fluids without inhibiting the electrostatic interactions between the polymer and DNA. Furthermore, glutathione (GSH) can act as a stimulus to open the nanoshell after it has entered the cell. The polyplexes coated with the bioreducible nanoshell show an obvious enhancement in gene transfection in vivo compared with bare polyplexes.

  4. Optically tunable nanoparticle contrast agents for early cancer detection: model-based analysis of gold nanoshells.

    Science.gov (United States)

    Lin, Alex W H; Lewinski, Nastassja A; West, Jennifer L; Halas, Naomi J; Drezek, Rebekah A

    2005-01-01

    Many optical diagnostic approaches rely on changes in scattering and absorption properties to generate optical contrast between normal and diseased tissue. Recently, there has been increasing interest in using exogenous agents to enhance this intrinsic contrast with particular emphasis on the development for targeting specific molecular features of disease. Gold nanoshells are a class of core-shell nanoparticles with an extremely tunable peak optical resonance ranging from the near-UV to the mid-IR wavelengths. Using current chemistries, nanoshells of a wide variety of core and shell sizes can easily be fabricated to scatter and/or absorb light with optical cross sections often several times larger than the geometric cross section. Using gold nanoshells of different size and optical parameters, we employ Monte Carlo models to predict the effect of varying concentrations of nanoshells on tissue reflectance. The models demonstrate the importance of absorption from the nanoshells on remitted signals even when the optical extinction is dominated by scattering. Furthermore, because of the strong optical response of nanoshells, a considerable change in reflectance is observed with only a very small concentration of nanoshells. Characterizing the optical behavior of gold nanoshells in tissue will aid in developing nanoshells as contrast agents for optical diagnostics.

  5. Synthesis of Dichloride-Diphenylacetonitrile Palladium and Metal-Polymer Composite Based on Uhmwpe

    Directory of Open Access Journals (Sweden)

    A. M. Nemeryuk

    2016-05-01

    Full Text Available New complex of Pd (II with phenylacetonitrile, suitable for use as a precursor of palladium nano particles in the composition of metal-based composite UHMWPE was obtained. The thermodynamic characteristics of metal-polymer composite, found the effect of nano particles of palladium in the crystallization processes in UHMWPE and other characteristics of the material.

  6. Effective Dielectric Response of Nonlinear Composites of Coated Metal Inclusions

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-Qing; WU Ya-Min

    2007-01-01

    The effective dielectric response of the composites in which nondilute coated metal particles are randomly embedded in a linear host is investigated. Two types of coated particles are considered, one is that the core is nonlinear, the other is that the shell is nonlinear. We derive general expressions for the effective linear dielectric function and the effective third-order nonlinear susceptibility, and take one step forward to perform numerical calculations on the coated metal/dielectric composites. Numerical results show that the effective linear and nonlinear dielectric responses can be greatly enhanced near the surface plasmon resonant frequency. Moreover, the resonant peaks are found within a range from 0.46ωp to 0.57ωp for spherical particles and from 0.59ωp to 0.7ωp for cylindrical inclusions. In the frequency region, the resonant peak can achieve the maximum, according to an optimal structural parameter and volume fraction. The resonant frequency exhibits a redshift with the increasing structural parameter k or volume fraction f or dimensionality factor D.

  7. Metal-Matrix Composites Prepared by Paper-Manufacturing Technology

    Science.gov (United States)

    Wenzel, Claudia; Aneziris, Christos G.; Pranke, Katja

    2016-01-01

    In this work, metal-matrix composites were prepared via paper-manufacturing technology using metastable austenitic steel powder of type 16-7-3 (Cr-Mn-Ni in wt pct) and magnesia partially stabilized zirconia reinforcing particles. The influence of the process parameters on the paper web formation and the resulting properties of the MMCs were studied and solids retention of >90 wt pct was achieved. During filtration of the aqueous fiber-filler suspension, the steel particles were incorporated in the fiber network, and steel clusters were formed. Calendering had a positive influence on the porosity, bulk density, and tensile strength of the green paper sheets. Within this contribution, the debinding process for the metal-matrix paper sheets was in focus. A debinding rate of 0.5 K/min to 733 K (460 °C) with a dwell time of 90 minutes was sufficient to completely remove cellulose fibers. The sintered composites attained a tensile strength of up to 177 N/mm2 at a total porosity of 66 pct.

  8. Monolithic oxide-metal composite thermoelectric generators for energy harvesting

    Science.gov (United States)

    Funahashi, Shuichi; Nakamura, Takanori; Kageyama, Keisuke; Ieki, Hideharu

    2011-06-01

    Monolithic oxide-metal composite thermoelectric generators (TEGs) were fabricated using multilayer co-fired ceramic technology. These devices consisted of Ni0.9Mo0.1 and La0.035Sr0.965TiO3 as p- and n-type thermoelectric materials, and Y0.03Zr0.97O2 was used as an insulator, sandwiched between p- and n-type layers. To co-fire dissimilar materials, p-type layers contained 20 wt. % La0.035Sr0.965TiO3; thus, these were oxide-metal composite layers. The fabricated device had 50 pairs of p-i-n junctions of 5.9 mm × 7.0 mm × 2.6 mm. The calculated maximum value of the electric power output from the device was 450 mW/cm2 at ΔT = 360 K. Furthermore, this device generated 100 μW at ΔT = 10 K and operated a radio frequency (RF) transmitter circuit module assumed to be a sensor network system.

  9. Composite reinforced metallic cylinder for? high-speed rotation

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The objective of the present study is to design and development of the composite reinforced thin metallic cylinder to increase the peripheral speed significantly and thereby? improve the separation performance in a centrifugal gas separation processes through? proper optimization of the internal parameters. According to Dirac equation (Cohen? (1951)), the maximum separative work for a centrifugal gas separation process increase? with 4th power of the peripheral speed. Therefore, it has been intended to reinforce the? metallic cylinder with composites (carbon fibers: T-700 and T- 1000 grade with suitable? epoxy resin) to increase the stiffness and hoop stress so that the peripheral speed can? be increased significantly, and thereby enhance the separative output. Here, we have developed the mathematical model to investigate the elastic stresses of? a laminated cylinder subjected to mechanical, thermal and thermo-mechanical loading? A detailed analysis is carried out to underline the basic hypothesis of each formulation? Further, we evaluate the steady state creep response of the rotating cylinder and analyze? the stresses and strain rates in the cylinder.

  10. A Novel Ionic Polymer Metal ZnO Composite (IPMZC

    Directory of Open Access Journals (Sweden)

    Sang-Mun Kim

    2011-04-01

    Full Text Available The presented research introduces a new Ionic Polymer-Metal-ZnO Composite (IPMZC demonstrating photoluminescence (PL-quenching on mechanical bending or application of an electric field. The newly fabricated IPMZC integrates the optical properties of ZnO and the electroactive nature of Ionic Polymer Metal Composites (IPMC to enable a non-contact read-out of IPMC response. The electro-mechano-optical response of the IPMZC was measured by observing the PL spectra under mechanical bending and electrical regimes. The working range was measured to be 375–475 nm. It was noted that the PL-quenching increased proportionally with the increase in curvature and applied field at 384 and 468 nm. The maximum quenching of 53.4% was achieved with the membrane curvature of 78.74/m and 3.01% when electric field (12.5 × 103 V/m is applied. Coating IPMC with crystalline ZnO was observed to improve IPMC transduction.

  11. Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Rupam; Huang, Zhi-Feng; Nadgorny, Boris [Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States)

    2014-10-27

    Multiple percolation transitions are observed in a binary system of RuO{sub 2}-CaCu{sub 3}Ti{sub 4}O{sub 12} metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO{sub 2} metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.

  12. Giant enhancement of magnetocaloric effect in metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    WANG YongTian; BAI HaiYang; PAN MingXiang; ZHAO DeQian; WANG WeiHua

    2008-01-01

    The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (△Sm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum △Sm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.

  13. Giant enhancement of magnetocaloric effect in metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (ΔSm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum ΔSm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zbib, Hussein M. [Washington State Univ., Pullman, WA (United States); Bahr, David F. [Purdue Univ., West Lafayette, IN (United States)

    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

  15. Amorphous Metal Composites for use in Long-Life, Low-Temperature Gearboxes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed concept is to explore the use of Amorphous Metals (AMs) and Amorphous Metal Composites (AMCs) (fabricated entirely at JPL) for use as gears and bearing...

  16. Novel concepts in weld metal science: Role of gradients and composite structure

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  17. Particulate Trace Metal Composition in Coastal Waters Surrounding Taiwan

    Science.gov (United States)

    Jiann, K. T.; Huang, K. C.; Hsieh, A. C.

    2016-02-01

    Coastal zones are dynamic environments where materials are transported from the land and where biomass is the most abundant, feeding on the terrestrial nutrients supplied. Therefore, compositions of particulate matter in coastal waters are complex. We collected size-fractionated particulate matter from Taiwan's coastal waters and determine trace metal concentrations, along with some key parameters that allow for the assessment of contribution of particulate matter from different sources. Al content in the particles is used to derive a mineralogical contribution (largely terrestrial) in the particle samples, based on the fact that Al concentrations in common clay minerals and in biota are 2-3 orders of magnitude different. Thereafter, trace metal concentrations in biotic particles can be derived after subtracting contribution from mineral particles (using a reference trace metal concentration in mineral phase), and the results can be compared directly. In the four size classes of particulate matter we collected (0.4-10 µm, 10-60 µm, 60-153 µm, and >153 µm), Al concentration, i.e. mineralogical contribution, decreased with increasing size. The derived biotic trace metal concentrations in near-shore coastal waters showed large variations in different size fractions. Biotic Cd concentrations increased with increasing particle size, implying bioaccumulation along the food chain. For Pb, higher concentrations were mostly associated with smaller size fractions. This may suggest the particle-reactive characteristics applied here for biotic particles. For other elements of biological and environmental significance, such as Cu, Ni, and Zn, their bulk particulate concentrations were relatively constant regardless sample locations and size fraction, but large variations in the biotic contents were found among different size fractions, as well as among samples collected from different locations with various extent of anthropogenic influence.

  18. Lubricating oil compositions containing overbased calcium sulfonates and metal salts of alkyl catechol dithiophosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, E.S.; Cerrito, E.; Liston, T.V.

    1987-05-26

    This patent describes a lubricating oil composition containing an overbased calcium hydrocarbyl sulfonate. The improvement wherein the lubricating oil composition additionally comprises an effective amount to reduce wear of a metal salt of an alkyl catechol dithiophosphoric acid ester of the formula: wherein R is alkyl containing 10 to 18 carbon atoms, or mixtures thereof, M is an alkali or alkaline earth metal or transition metal and n corresponds to the valence of the metal M.

  19. Slow and fast light in metal/dielectric composites with passive and active host matrices

    Energy Technology Data Exchange (ETDEWEB)

    Mal' nev, V.N., E-mail: vadimmalnev@yahoo.com; Shewamare, Sisay, E-mail: sisayshewa20@yahoo.com

    2013-10-01

    The optical properties of metal/dielectric composites (metal with dielectric core and pure metal inclusions) in passive and active host matrices are studied. It is shown that the real and imaginary parts of the refractive index of the composites with metal covered inclusions have two maxima at two resonant frequencies. Both types of composites show strong anomalous dispersion of the real part of refractive index. The active host matrices can considerably reduce the absorption and provide the conditions for the propagation of weakly damping light waves at the resonant frequencies. The weakly spreading wave packets of light with negative group velocity can be experimentally observed in these composites.

  20. Non-blinking quantum dot with a plasmonic nanoshell resonator

    Science.gov (United States)

    Ji, Botao; Giovanelli, Emerson; Habert, Benjamin; Spinicelli, Piernicola; Nasilowski, Michel; Xu, Xiangzhen; Lequeux, Nicolas; Hugonin, Jean-Paul; Marquier, Francois; Greffet, Jean-Jacques; Dubertret, Benoit

    2015-02-01

    Colloidal semiconductor quantum dots are fluorescent nanocrystals exhibiting exceptional optical properties, but their emission intensity strongly depends on their charging state and local environment. This leads to blinking at the single-particle level or even complete fluorescence quenching, and limits the applications of quantum dots as fluorescent particles. Here, we show that a single quantum dot encapsulated in a silica shell coated with a continuous gold nanoshell provides a system with a stable and Poissonian emission at room temperature that is preserved regardless of drastic changes in the local environment. This novel hybrid quantum dot/silica/gold structure behaves as a plasmonic resonator with a strong Purcell factor, in very good agreement with simulations. The gold nanoshell also acts as a shield that protects the quantum dot fluorescence and enhances its resistance to high-power photoexcitation or high-energy electron beams. This plasmonic fluorescent resonator opens the way to a new family of plasmonic nanoemitters with robust optical properties.

  1. Atomic-focuser imaging in electron nanodiffraction from carbon nanoshells

    Science.gov (United States)

    Cowley

    2000-03-01

    When nanodiffraction patterns are obtained by transmission through the top and bottom walls of near-spherical, hollow carbon nano-shells, using the focused probe of a STEM instrument, a graphitic crystal in one wall may act as an atomic focuser to produce high-resolution images of small regions of the other wall within the central beam and the diffraction disks of the nanodiffraction pattern. A theoretical analysis of the imaging process is given. Images showing one- and two-dimensional periodicities, with fringe spacings as small as 0.124 nm, and also images showing non-periodic features have been obtained from carbon nanoshells having diameters of the order of 100 nm.

  2. Advantages of using gold hollow nanoshells in cancer photothermal therapy

    Science.gov (United States)

    Abbasi, Sattar; Servatkhah, Mojtaba; Keshtkar, Mohammad Mehdi

    2016-08-01

    Lots of studies have been conducted on the optical properties of gold nanoparticles in the first region of near infrared (650 nm-950 nm), however new findings show that the second region of near-infrared (1000 nm-1350 nm) penetrates to the deeper tissues of the human body. Therefore, using the above-mentioned region in photo-thermal therapy (PTT) of cancer will be more appropriate. In this paper, absorption efficiency is calculated for gold spherical and rod-shaped nanoshells by the finite element method (FEM). The results show that the surface plasmon frequency of these nanostructures is highly dependent on the dimension and thickness of shell and it can be adjusted to the second region of near-infrared. Thus, due to their optical tunability and their high absorption efficiency the hollow nanoshells are the most appropriate options for eradicating cancer tissues.

  3. Metal salts of alkyl catechol dithiophosphoric acids and oil compositions containing the salts

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, E.S.; Liston, T.V.

    1988-03-08

    Metal salts of alkyl catechol esters of dithiophosphoric acid suitable as additives in oil compositions are disclosed in this patent. Oil compositions containing the salts of such esters show improved extreme pressure/anti-wear and anit-oxidant properties.

  4. Gold nanoshell mediated hyperthermia enhances the efficacy of radiation therapy

    Science.gov (United States)

    Diagaradjane, Parmeswaran; Shetty, Anil; Wang, James; Elliot, Andrew; Schwartz, Jon; Shentu, Shujun; Park, Chul; Deorukhkar, Amit; Stafford, Jason; Cho, Sang; Tunnell, James; Hazle, John; Krishnan, Sunil

    2008-02-01

    Despite convincing evidence for hyperthermic radiosensitization, the invasive means of achieving and monitoring hyperthermia and the lack of good thermal dosimetry have hindered its use in routine clinical practice. A non-invasive method to generate and monitor hyperthermia would provide renewed enthusiasm for such treatments. Near-infrared absorbing gold nanoshells have been shown to accumulate preferentially in tumors via the enhanced permeability and retention effect and have been used for thermal ablation of tumors. We evaluated the use of these nanoshells to generate hyperthermia to evaluate the anti-tumor effects of combining gold nanoshell mediated hyperthermia with radiotherapy. Laser settings were optimized for hyperthermia in a mouse xenograft model to achieve a temperature rise of 40- 41°C in the tumor periphery and 37-38°C (ΔT=4-5°C) deeper within the tumors. The ΔT measurements were verified using both thermocouple and magnetic resonance thermal imaging (MRTI) temperature measurements. Tumor re-growth delay was estimated by measuring tumor size after treatment with radiation (10Gy single dose), hyperthermia (15 minutes at 40°C), and hyperthermia followed by radiation and control. Significant difference (p time was observed between the radiation group (13 days) and combination treatment group (25 days). The immunofluorescence staining for the hypoxic, proliferating cells and the vasculature corroborated our hypothesis that the radiosensitization is in part mediated by increased initial perfusion and subsequent collapse of vasculature that leads to acute inflammatory response in the tumor. The increased vascular perfusion immediately after gold nanoshell mediated hyperthermia is confirmed by dynamic contrast enhanced magnetic resonance imaging.

  5. Electromechanical modelling of tapered ionic polymer metal composites transducers

    Directory of Open Access Journals (Sweden)

    Rakesha Chandra Dash

    2016-09-01

    Full Text Available Ionic polymer metal composites (IPMCs are relatively new smart materials that exhibit a bidirectional electromechanical coupling. IPMCs have large number of important engineering applications such as micro robotics, biomedical devices, biomimetic robotics etc. This paper presents a comparison between tapered and uniform cantilevered Nafion based IPMCs transducer. Electromechanical modelling is done for the tapered beam. Thickness can be varied according to the requirement of force and deflection. Numerical results pertaining to the force and deflection characteristics of both type IPMCs transducer are obtained. It is shown that the desired amount of force and deflections for tapered IPMCs can be achieved for a given voltage. Different fixed end (t0 and free end (t1 thickness values have been taken to justify the results using MATLAB.

  6. Manufacture and Performance of Ionic Polymer-Metal Composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ion-exchange Polymer Metal Composites (IPMC) are a new class of intelligent material that can be used effectively as actuators and artificial muscles. IPMC was fabricated and its displacement and force characteristics were investigated with respect to voltage, frequency and waveform of the controlling signal. A square waveform input generated slightly larger displacement and force than sinusoidal or triangular waveform. When the voltage was increased and the frequency was decreased,displacement and force were both increased. However, although the bending deformation of IPMC was large, the output force was much lower than we expected. Improvement of the force output is key and is the main obstacle to be overcome in order to make IPMC of practical use.

  7. Manufacturing Titanium Metal Matrix Composites by Consolidating Matrix Coated Fibres

    Institute of Scientific and Technical Information of China (English)

    Hua-Xin PENG

    2005-01-01

    Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing (VHP). In contrast to most of existing studies, the fibre arrangement has been carefully controlled either in square or hexagonal arraysthroughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.

  8. In Vitro Effects of Hollow Gold Nanoshells on Human Aortic Endothelial Cells

    Science.gov (United States)

    Gu, Chunrong; Wu, Hengfang; Ge, Gaoyuan; Li, Xiongzhi; Guo, Zhirui; Bian, Zhiping; Xu, Jindan; Lu, Hua; Chen, Xiangjian; Yang, Di

    2016-09-01

    Gold nanoparticles are emerging as promising biomedical tools due to their unique nanoscale characteristics. Our purpose was to synthesize a hollow-shaped gold nanoparticle and to investigate its effect on human aortic endothelial cells (HAECs) in vitro. Hollow gold nanoshells with average 35-nm diameters and 10-nm shell thickness were obtained by galvanic replacement using quasi-spherical nanosilver as sacrifice-template. Our results showed that hollow gold nanoshells in the culture medium could be internalized into the cytoplasm of HAECs. No cytotoxicity effect of hollow gold nanoshells on HAECs was observed within the test concentrations (0-0.8 μg/mL) and test exposure period (0-72 h) by tetrazolium dye assay. Meanwhile, the release of cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without hollow gold nanoshells). The concentrations of vasodilators, nitric oxide, and prostacyclin I-2 were not changed, but the vasoconstrictor endothelin-1 was decreased by hollow gold nanoshells treatment in HAECs. HAECs exposed to hollow gold nanoshells resulted in suppressing expressions of genes involved in apoptosis and activating expressions of genes of adhesion molecules. Moreover, we demonstrated by in vitro endothelial tube formation that hollow gold nanoshells (0.8 μg/mL) could not inhibit angiogenesis by the HAECs. Altogether, these results indicate that the structure and major function of HAECs would not be disrupted by hollow gold nanoshell treatment.

  9. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.

    Science.gov (United States)

    Li, Zihui; Sai, Hiroaki; Warren, Scott C; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules.

  10. Condensation Dynamics on Mimicked Metal Matrix Hydrophobic Nanoparticle-Composites

    Science.gov (United States)

    Damle, Viraj; Sun, Xiaoda; Rykaczewski, Konrad

    2014-11-01

    Use of hydrophobic surfaces promotes condensation in the dropwise mode, which is significantly more efficient than the common filmwise mode. However, limited longevity of hydrophobic surface modifiers has prevented their wide spread use in industry. Recently, metal matrix composites (MMCs) having microscale hydrophobic heterogeneities dispersed in hydrophilic metal matrix have been proposed as durable and self-healing alternative to hydrophobic surface coatings interacting with deposited water droplets. While dispersion of hydrophobic microparticles in MMC is likely to lead to surface flooding during condensation, the effect of dispersion of hydrophobic nanoparticles (HNPs) with size comparable to water nuclei critical radii and spacing is not obvious. To this end, we fabricated highly ordered arrays of Teflon nanospheres on silicon substrates that mimic the top surface of the MMCs with dispersed HNPs. We used light and electron microscopy to observe breath figures resulting from condensation on these surfaces at varied degrees of subcooling. Here, we discuss the relation between the droplet size distribution, Teflon nanosphere diameter and spacing, and condensation mode. KR acknowledges startup funding from ASU.

  11. New Joining Technology for Optimized Metal/Composite Assemblies

    Directory of Open Access Journals (Sweden)

    Holger Seidlitz

    2014-01-01

    Full Text Available The development of a new joining technology, which is used to manufacture high strength hybrid constructions with thermoplastic composites (FRP and metals, is introduced. Similar to natural regulation effects at trees, fibers around the FRP joint become aligned along the lines of force and will not be destroyed by the joining process. This is achieved by the local utilization of the specific plastic flow properties of the FRT and metal component. Compared with usual joining methods—such as flow drill screws, blind and self-piercing rivets—noticeably higher tensile properties can be realized through the novel process management. The load-bearing capability increasing effect could be proved on hybrid joints with hot-dip galvanized steel HX420LAD and orthotropic glass—as well as carbon—fiber reinforced plastics. The results, which were determined in tensile-shear and cross-shear tests according to DIN EN ISO 14273 and DIN EN ISO 14272, are compared with holding loads of established joining techniques with similar joining point diameter and material combinations.

  12. Single-step preparation and consolidation of reduced early-transition-metal oxide/metal n-type thermoelectric composites

    Directory of Open Access Journals (Sweden)

    Michael W. Gaultois

    2015-09-01

    Full Text Available Reduced early transition metal oxides/metal composites have been identified here as interesting thermoelectric materials. Numerous compositions in the Nb-rich portion of the WO3–Nb2O5 system have been studied, in composite formulations with elemental W. Spark plasma sintering (SPS has been employed to achieve rapid preparation and consolidation of composite materials containing W metal precipitates with characteristic length scales that range from under 20 nm to a few microns, that exhibit thermal conductivities that are constant from 300 K to 1000 K, approximately 2.5 W m−1 K−1. Thermoelectric properties of these n-type materials were measured, and the highest-performing compositions were found to reach figure of merit zT values close to 0.1 at 950 K. The measurements point to higher zT values at yet-higher temperatures.

  13. Iron(III)-doped, silica nanoshells: a biodegradable form of silica.

    Science.gov (United States)

    Pohaku Mitchell, Kristina K; Liberman, Alexander; Kummel, Andrew C; Trogler, William C

    2012-08-29

    Silica nanoparticles are being investigated for a number of medical applications; however, their use in vivo has been questioned because of the potential for bioaccumulation. To obviate this problem, silica nanoshells were tested for enhanced biodegradability by doping iron(III) into the nanoshells. Exposure of the doped silica to small molecule chelators and mammalian serum was explored to test whether the removal of iron(III) from the silica nanoshell structure would facilitate its degradation. Iron chelators, such as EDTA, desferrioxamine, and deferiprone, were found to cause the nanoshells to degrade on the removal of iron(III) within several days at 80 °C. When the iron(III)-doped, silica nanoshells were submerged in fetal bovine and human serums at physiological temperature, they also degrade via removal of the iron by serum proteins, such as transferrin, over a period of several weeks.

  14. Macrophages as cell-based delivery systems for nanoshells in photothermal therapy.

    Science.gov (United States)

    Madsen, Steen J; Baek, Seung-Kuk; Makkouk, Amani R; Krasieva, Tatiana; Hirschberg, Henry

    2012-02-01

    Site-specific delivery of nanoparticles poses a significant challenge, especially in the brain where the blood-brain barrier prevents the entry of most therapeutic compounds including nanoparticle-based anti-cancer agents. In this context, the use of macrophages as vectors for the delivery of gold-silica nanoshells to infiltrating gliomas will be reviewed in this article. Gold-silica nanoshells are readily phagocytosed by macrophages without any apparent toxic effects, and the results of in vitro studies have demonstrated the migratory potential of nanoshell-loaded macrophages in human glioma spheroids. Of particular interest is the observation that, after near-infrared exposure of spheroids containing nanoshell-loaded macrophages, sufficient heat was generated to suppress spheroid growth. Collectively, these findings demonstrate the potential of macrophages as nanoshell delivery vectors for photothermal therapy of gliomas, and they certainly provide the basis for future animal studies.

  15. Damage tolerance of bonded composite aircraft repairs for metallic structures

    Science.gov (United States)

    Clark, Randal John

    This thesis describes the development and validation of methods for damage tolerance substantiation of bonded composite repairs applied to cracked plates. This technology is used to repair metal aircraft structures, offering improvements in fatigue life, cost, manufacturability, and inspectability when compared to riveted repairs. The work focuses on the effects of plate thickness and bending on repair life, and covers fundamental aspects of fracture and fatigue of cracked plates and bonded joints. This project falls under the UBC Bonded Composite Repair Program, which has the goal of certification and widespread use of bonded repairs in civilian air transportation. This thesis analyses the plate thickness and transverse stress effects on fracture of repaired plates and the related problem of induced geometrically nonlinear bending in unbalanced (single-sided) repairs. The author begins by developing a classification scheme for assigning repair damage tolerance substantiation requirements based upon stress-based adhesive fracture/fatigue criteria and the residual strength of the original structure. The governing equations for bending of cracked plates are then reformulated and line-spring models are developed for linear and nonlinear coupled bending and extension of reinforced cracks. The line-spring models were used to correct the Wang and Rose energy method for the determination of the long-crack limit stress intensity, and to develop a new interpolation model for repaired cracks of arbitrary length. The analysis was validated using finite element models and data from mechanical tests performed on hybrid bonded joints and repair specimens that are representative of an in-service repair. This work will allow designers to evaluate the damage tolerance of the repaired plate, the adhesive, and the composite patch, which is an airworthiness requirement under FAR (Federal Aviation Regulations) 25.571. The thesis concludes by assessing the remaining barriers to

  16. Elemental composition of brazing alloys in metallic orthodontic brackets.

    Science.gov (United States)

    Zinelis, Spiros; Annousaki, Olga; Eliades, Theodore; Makou, Margarita

    2004-06-01

    The aim of this study was to assess the elemental composition of the brazing alloy of representative orthodontic brackets. The brackets examined were Gemini (3M, Unitec, Monrovia, Calif), MicroLoc (GAC, Bohemia, NY), OptiMESHxrt (Ormco, Glendora, Calif), and Ultratrim (Dentarum, Ispringen, Germany). Four metallic brackets for each brand were embedded in epoxy resin and after metallographic grinding and polishing were cleaned in a water ultrasonic bath. Scanning electron microscopy and energy-dispersive x-ray microanalysis (EDS) were used to assess the quantitative composition of the brazing alloy. Four EDS spectra were collected for each brazing alloy, and the mean value and standard deviation for the concentration of each element were calculated. The elemental composition of the brazing alloys was determined as follows (percent weight): Gemini: Ni = 83.98 +/- 1.02, Si = 6.46 +/- 0.37, Fe = 5.90 +/- 0.93, Cr = 3.52 +/- 0.34; MicroLoc: Ag = 42.82 +/- 0.18, Au = 32.14 +/- 0.65, Cu = 24.53 +/- 0.26, Mg = 1.12 +/- 0.33; OptiMESHxrt: Au = 67.79 +/- 0.97, Fe = 15.69 +/- 0.29, Ni = 13.01 +/- 0.93, Cr = 4.01 +/- 0.35; Ultratrim: Ag = 87.97 +/- 0.33, Cu = 10.51 +/- 0.45, Mg = 1.29 +/- 0.63, Zn = 1.13 +/- 0.24. The findings of this study showed that different brazing materials were used for the different brands, and thus different performances are expected during intraoral exposure; potential effects on the biological properties also are discussed.

  17. Laser beam drilling of metal-based composites

    Science.gov (United States)

    Riegel, H.; Merkel, M.; Ã-chsner, A.

    2014-02-01

    Laser drilling is a highly efficient technique to generate holes in almost any material. The relatively small amount of heat being involved during the process results in a small heat affected zone. This characteristic makes laser processing interesting for composite materials. The drilling process has to be adapted to the special characteristics of the composite material. In this paper investigations were performed with an advanced composite material, that is a metallic hollow sphere structure (MHSS). Numerical simulation was used to predict heat flux and temperature levels for different geometric parameters of the spheres (diameter, wall thickness) in order to optimize the drilling process. The numerical simulation allows a detailed analysis of the physical process in the zone that is influenced by the laser beam, which can hardly be analyzed by any measuring technique. The models for transient numerical analysis consider heat conduction and convection. The experimental work was done by a CO2-laser. The percussion drilling method has been used as drilling technique. The pulse duration was in the millisecond time regime. Investigations have been done with a mean power of 100 W, 200 W and 400 W. Two focal lenses have been used with focal lengths of 5.0´´ and 7.5´´. The laser beam melts the hollow sphere structure inside the beam leaving a hole in the structure as well as in individual hollow spheres. An image processing technique was developed to determine the circularity on the spheres and the drilled diameter in the structure. The circularity declines with increasing drill depth. The diameter as function of depth can be well described with lines of constant intensity of the focussed laser beam, the isophotes.

  18. Thin metal film-polymer composite for efficient optoacoustic generation (Conference Presentation)

    Science.gov (United States)

    Lee, Taehwa; Guo, L. Jay

    2016-03-01

    Photoacoustic (PA) conversion of metal film absorbers is known to be inefficient because of their low thermal expansion and high light reflectance, as compared to polymeric materials containing light absorbing fillers. Specifically, the PA signal for metal films is typically an order of magnitude lower than those for PDMS-based composites consisting of carbon materials such as carbon blacks, carbon nanotubes, and carbon fibers. However, the carbon-PDMS composites have several disadvantages, e.g., difficulty in controlling film thickness, aggregation of the carbon fillers, and poor patternablility. To overcome these issues and achieve comparable PA amplitudes, a polymer-metal film composite was developed consisting of a thin metal absorber and adjacent transparent polymer layers. The proposed structure shows efficient PA conversion. The measured PA amplitude of the metal film composite is an order of magnitude higher than that of metal-only samples, and comparable to those of the carbon-PDMS composites. The enhanced PA conversion is accomplished by using metal film of a few tens of nanometers, which greatly facilitates heat transfer from the metal film to the surrounding polymers. Moreover, integrating the metal film composite with a photonic cavity can compensate light absorption loss of the thinner metal film. Theoretical and experimental analysis is conducted for understanding the mechanism behind such improvement. This strategy could be implemented for spatial PA signal patterns, especially for deep tissue PA imaging of implants or image-guiding tools. Furthermore, this approach also provides a guideline for designing photoacoustic transmitters and contrast agents.

  19. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... cemented prosthesis. 888.3100 Section 888.3100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  20. 21 CFR 888.3340 - Hip joint metal/composite semi-constrained cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... cemented prosthesis. 888.3340 Section 888.3340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Hip joint metal/composite semi-constrained cemented prosthesis. (a) Identification. A hip joint metal/composite semi-constrained cemented prosthesis is a two-part device intended to be implanted to replace...

  1. Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wen [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Banerjee, Debasis [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Liu, Jian [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Schaef, Herbert T. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Crum, Jarrod V. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Fernandez, Carlos A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Kukkadapu, Ravi K. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nie, Zimin [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nune, Satish K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Motkuri, Radha K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Chapman, Karena W. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Hayes, James C. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Silvers, Kurt L. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Krishna, Rajamani [Van' t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904 1098 XH Amsterdam The Netherlands; McGrail, B. Peter [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Liu, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Thallapally, Praveen K. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-03-08

    A redox-active metal-organic composite material shows improved and selective O-2 adsorption over N-2 with respect to individual components (MIL-101 and ferrocene). The O-2 sensitivity of the composite material arises due to the formation of maghemite nanoparticles with the pore of the metal-organic framework material.

  2. Surface modification with zwitterionic cysteine betaine for nanoshell-assisted near-infrared plasmonic hyperthermia.

    Science.gov (United States)

    Huang, Chun-Jen; Chu, Sz-Hau; Li, Chien-Hung; Lee, T Randall

    2016-09-01

    Nanoparticles decorated with biocompatible coatings have received considerable attention in recent years for their potential biomedical applications. However, the desirable properties of nanoparticles for in vivo uses, such as colloidal stability, biodistribution, and pharmacokinetics, require further research. In this work, we report a bio-derived zwitterionic surface ligand, cysteine betaine (Cys-b) for the modification of hollow gold-silver nanoshells, giving rise to hyperthermia applications. Cys-b coatings on planar substrates and nanoshells were compared to conventional (11-mercaptoundecyl)tri(ethylene glycol) (OEG-thiol) to investigate their effects on the fouling resistance, colloidal stability, environmental tolerance, and photothermal properties. The results found that Cys-b and OEG-thiol coatings exhibited comparable antifouling properties against bacteria of gram-negative Pseudomonas aeruginosa (P. aeruginosa) and gram-positive Staphylococcus epidermidis (S. epidermidis), NIH-3T3 fibroblasts, and bovine serum albumin. However, when the modified nanoshells were suspended at a temperature of 50°C in aqueous 3M NaCl solutions, shifts in the extinction maximum of the OEG-capped nanoshells with time were observed, while the corresponding spectra of nanoshells capped with Cys-b generally remained unchanged. In addition, when the nanoshells were continuously exposed to NIR irradiation, the temperature of the solution containing nanoshells capped with Cys-b increased to a plateau of 54°C, while that of the OEG-capped nanoshells gradually decreased after reaching a peak temperature. Accordingly, the Cys-b nanoshells were conjugated with anti-HER2 antibodies for targeted delivery to HER2-positive MDA-MB-453 breast cancer cells for hyperthermia treatment. The results showed the selective delivery and effective photothermal cell ablation with the antibody-conjugated Cys-b nanoshells. Therefore, this work demonstrated the promise of bio-derived zwitterionic Cys

  3. Contribution of trace metals in structuring in situ macroinvertebrate community composition along a salinity gradient

    NARCIS (Netherlands)

    Peeters, E.T.H.M.; Gardeniers, J.J.P.; Koelmans, A.A.

    2000-01-01

    Macroinvertebrates were studied along a salinity gradient in the North Sea Canal, The Netherlands, to quantify the effect of trace metals (cadmium, copper, lead, zinc) on community composition. In addition, two methods for assessing metal bioavailability (normalizing metal concentrations on organic

  4. Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

    Institute of Scientific and Technical Information of China (English)

    BAI Xue; WANG TongLe; CUI YuanYuan; DING Ning; LI JiaHao; LIU BaiXin

    2012-01-01

    Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium.It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around Cu17Mo20Hf63 and Cu34Mo57Hf9,respectively.Interestingly,at the nearly equal-atomic stoichiometry of Cu38Mo31Hf31,a dual-phase Cu-Mo-Hf metallic glass,consisting both of the Mo-Hf-based and Cu-Mo-based phases,was first obtained at relatively low irradiation doses ranging from (1-5)×1015 Xe+/cm2,and a single-phase metallic glass was eventually obtained at a dose of 7×1015 Xe+/cm2.In addition,two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9,and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses,dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions,respectively.The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.

  5. Modelling compression sensing in ionic polymer metal composites

    Science.gov (United States)

    Volpini, Valentina; Bardella, Lorenzo; Rodella, Andrea; Cha, Youngsu; Porfiri, Maurizio

    2017-03-01

    Ionic polymer metal composites (IPMCs) consist of an ionomeric membrane, including mobile counterions, sandwiched between two thin noble metal electrodes. IPMCs find application as sensors and actuators, where an imposed mechanical loading generates a voltage across the electrodes, and, vice versa, an imposed electric field causes deformation. Here, we present a predictive modelling approach to elucidate the dynamic sensing response of IPMCs subject to a time-varying through-the-thickness compression (‘compression sensing’). The model relies on the continuum theory recently developed by Porfiri and co-workers, which couples finite deformations to the modified Poisson–Nernst–Planck (PNP) system governing the IPMC electrochemistry. For the ‘compression sensing’ problem we establish a perturbative closed-form solution along with a finite element (FE) solution. The systematic comparison between these two solutions is a central contribution of this study, offering insight on accuracy and mathematical complexity. The method of matched asymptotic expansions is employed to find the analytical solution. To this end, we uncouple the force balance from the modified PNP system and separately linearise the PNP equations in the ionomer bulk and in the boundary layers at the ionomer–electrode interfaces. Comparison with FE results for the fully coupled nonlinear system demonstrates the accuracy of the analytical solution to describe IPMC sensing for moderate deformation levels. We finally demonstrate the potential of the modelling scheme to accurately reproduce experimental results from the literature. The proposed model is expected to aid in the design of IPMC sensors, contribute to an improved understanding of IPMC electrochemomechanical response, and offer insight into the role of nonlinear phenomena across mechanics and electrochemistry.

  6. Nanosensors having dipicolinic acid imprinted nanoshell for Bacillus cereus spores detection

    Energy Technology Data Exchange (ETDEWEB)

    Gueltekin, Aytac [Trakya University, Department of Chemistry (Turkey); Ersoez, Arzu [Anadolu University, Department of Chemistry, Faculty of Science, Yunusemre Campus (Turkey); Sarioezlue, Nalan Yilmaz [Anadolu University, Department of Biology (Turkey); Denizli, Adil [Hacettepe University, Department of Chemistry (Turkey); Say, Ridvan, E-mail: rsay@anadolu.edu.t [Anadolu University, Department of Chemistry, Faculty of Science, Yunusemre Campus (Turkey)

    2010-08-15

    Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP nanoclusters have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to gold-silver nanoclusters, reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for recognition. In this method, methacryloylamidoantipyrine-terbium ((MAAP){sub 2}-Tb(III)) has been used as a new metal-chelating monomer via metal coordination-chelation interactions and dipicolinic acid (DPA) which is main participant of Bacillus cereus spores used as a model. Nanoshell sensors with templates give a cavity that is selective for DPA. The DPA can simultaneously chelate to Tb(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Tb(III) ion and free coordination spheres has an effect on the binding ability of the gold-silver nanoclusters nanosensor. The binding affinity of the DPA imprinted nanoclusters has been investigated by using the Langmuir and Scatchard methods, and the respective affinity constants (K{sub affinity}) determined were found to be 1.43 x 10{sup 4} and 9.1 x 10{sup 6} mol L{sup -1}.

  7. Wear Resistance of Friction Pair of Metal Composite/Copper under Electric Current

    Science.gov (United States)

    Aleutdinova, M. I.; Fadin, V. V.; Rubtsov, V. Ye; Aleutdinov, K. A.

    2016-11-01

    Sliding of metal composites against copper counterbody under severe conditions (i.e. at the contact current density higher 50 A/cm2 and at high roughness of counterbody) is carried out. It is shown that the composite of composition of Cu-30% of graphite shows low wear resistance in these conditions. Higher wear resistance is inherent in the composites containing lead and bearing steel. Impregnation of these composites by industrial oil hasn't led to noticeable increase in wear resistance.

  8. Effect of intratumoral administration on biodistribution of 64Cu-labeled nanoshells

    Directory of Open Access Journals (Sweden)

    Xie H

    2012-05-01

    Full Text Available Huan Xie1, Beth Goins2, Ande Bao2, Zheng Jim Wang3, William T Phillips21Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX, 2Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 3MPI Research Inc, Mattawan, MIBackground: Gold nanoshells are excellent agents for photothermal ablation cancer therapy and are currently under clinical trial for solid tumors. Previous studies showed that passive delivery of gold nanoshells through intravenous administration resulted in limited tumor accumulation, which represents a major challenge for this therapy. In this report, the impact of direct intratumoral administration on the pharmacokinetics and biodistribution of the nanoshells was systematically investigated.Methods: The gold nanoshells were labeled with the radionuclide, copper-64 (64Cu. Intratumoral infusion of 64Cu-nanoshells and two controls, ie, 64Cu-DOTA (1,4,7,10-tetraazaciclododecane-1,4,7,10-tetraacetic acid and 64Cu-DOTA-PEG (polyethylene glycol, as well as intravenous injection of 64Cu-nanoshells were performed in nude rats, each with a head and neck squamous cell carcinoma xenograft. The pharmacokinetics was determined by radioactive counting of serial blood samples collected from the rats at different time points post-injection. Using positron emission tomography/computed tomography imaging, the in vivo distribution of 64Cu-nanoshells and the controls was monitored at various time points after injection. Organ biodistribution in the rats at 46 hours was analyzed by radioactive counting and compared between the different groups.Results: The resulting pharmacokinetic curves indicated a similar trend between the intratumorally injected agents, but a significant difference with the intravenously injected 64Cu-nanoshells. Positron emission tomography images and organ biodistribution results on rats after intratumoral administration

  9. Theranostic nanoshells: from probe design to imaging and treatment of cancer.

    Science.gov (United States)

    Bardhan, Rizia; Lal, Surbhi; Joshi, Amit; Halas, Naomi J

    2011-10-18

    Recent advances in nanoscience and biomedicine have expanded our ability to design and construct multifunctional nanoparticles that combine targeting, therapeutic, and diagnostic functions within a single nanoscale complex. The theranostic capabilities of gold nanoshells, spherical nanoparticles with silica cores and gold shells, have attracted tremendous attention over the past decade as nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement. This Account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties, and their corresponding applications. We discuss the design and preparation of nanoshell complexes and their ability to enhance the photoluminescence of fluorophores while maintaining their properties as MR contrast agents. In this Account, we discuss the underlying physical principles that contribute to the photothermal response of nanoshells. We then elucidate the photophysical processes that induce nanoshells to enhance the fluorescence of weak near-infrared fluorophores. Nanoshells illuminated with resonant light are either strong optical absorbers or scatterers, properties that give rise to their unique capabilities. These physical processes have been harnessed to visualize and eliminate cancer cells. We describe the application of nanoshells as a contrast agent for optical coherence tomography of breast carcinoma cells in vivo. Our recent studies examine nanoshells as a multimodal theranostic probe, using these nanoparticles for near-infrared fluorescence and magnetic resonance imaging (MRI) and for the photothermal ablation of cancer cells. Multimodal nanoshells show theranostic potential for imaging subcutaneous breast cancer tumors in animal models and the distribution of tumors in various tissues. Nanoshells also show promise as light-triggered gene therapy vectors, adding temporal control to the spatial control characteristic of nanoparticle-based gene

  10. High-Strain-Rate Constitutive Characterization and Modeling of Metal Matrix Composites

    Science.gov (United States)

    2014-03-07

    impact fracture of carbon fiber reinforced 7075 -T6 aluminum matrix composite , Materials Transactions, Japan Institute of Metals, 41, 1055-1063...MODELING OF METAL MATRIX COMPOSITES Report Title The mechanical response of three different types of materials are examined: unidirectionally...conditions. This report also documents some of the highlights of the material response of Saffil filled aluminum matrix composite and a Nextel satin

  11. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    Science.gov (United States)

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-04-12

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  12. Preparation and Study of Hollow Nanoshells%C_(60)空心纳米壳的制备及研究

    Institute of Scientific and Technical Information of China (English)

    刘珵; 董威红; 刘淼; 张洋; 范楼珍

    2009-01-01

    C_(60) hollow nanoshells were firstly prepared in a binary organic solution of m-xylene and ace-tonitrile by applying ultrasonication.The morphologies of C_(60) hollow nanoshells were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The-outer diameter and inner diameter were 300~400 nm and 200~300 nm respectively,and the thickness of the wall was about 100 nm.The image of TEM certified that the sample took a hollow structure.XRD and FTIR spectrum results showed that the C_(60) hollow nanoshells were of a single crystalline structure and composed of pristine C_(60) molecules.The uniform C_(60) hollow nanoshell electrode was prepared by electrophoresis and the Au nanoparticles were then deposited by an electrochemical reduction method.The following depositions of other metals are continuing.The applications of these metal/C_(60) hollow nanoshell electrodes to the biosensors and fuel cells are being studied.%利用超声技术,选择间二甲苯溶液和乙腈两种不互溶的溶剂,首次成功地制备了C_(60)的空心纳米壳.选择扫描电镜(SEM),透射电镜(TEM)等对所制得的C_(60)的空心纳米壳的形貌及结构进行表征.C_(60)空心纳米壳的外直径为300~400nm,内直径为200~300 nm,壁厚约100 nm.X射线衍射光谱(XRD)、傅里叶红外光谱检测结果表明其为C_(60)分子组成的单晶结构.利用电泳方法制备了均匀的C_(60)的空心纳米壳膜电极,并利用电沉积方法在所制备的C_(60)的空心纳米壳电极表面沉积了金(Au)纳米颗粒.为进一步沉积其它金属,研究其在生物传感器及燃料电池方面的应用提供了基础.

  13. The morphology of carbon-metal composite synthesized in arc discharge

    Science.gov (United States)

    Smovzh, D. V.; Sakhapov, S. Z.; Zaikovskii, A. V.

    2016-10-01

    The phase state of nanoparticles and function of distribution by size of particles, formed at joint electric arc spraying of metal (Ni/Cu/Ti/Pt/Zr) - carbon electrode, is studied. It is shown that the metal and carbide nanoparticles with the size of 2-9 nm are formed in the carbon matrix at spraying. When annealing the metal-carbon composites, the metal-containing nanoparticles oxidize and coagulate, forming the agglomerates of 100 nm or more.

  14. Interfacial effects on the behavior of partially bonded metal matrix composite properties

    Science.gov (United States)

    Caruso, J. J.; Chamis, C. C.

    1990-01-01

    A novel computational method developed at NASA-Lewis in order to predict the behavior of unidirectional composites has been used to explore the effects of partial debonding and fiber fracture on the behavior of room temperature and high temperature metal-matrix composites. Attention is presently given to the influence of disbonding, which occurs with fractured fibers, on the ply properties of metal-matrix composites with orthotropic fibers, in the case of a graphite fiber-reinforced copper-matrix composite. It is shown that, for small amounts of partial bonding on fractured fibers, composite material properties are not significantly affected.

  15. Neutron diffraction study of metal-matrix composite with fullerite

    Science.gov (United States)

    Borisova, P. A.; Blanter, M. S.; Brazhkin, VV; Somenkov, VA; Filonenko, V. P.

    2016-09-01

    Interaction of amorphous fullerite C60 with austenitic Fe-33.2 wt. % Ni alloy at pressures 0-8 GPa and temperatures 600-1100 °C was studied by neutron diffraction. The amorphous fullerite was obtained by ball milling and mixed with the powder of the crystalline alloy. The interaction at sintering led to the dissolution of carbon in fcc Fe-Ni solid solution and the formation of carbide (Fe, Ni)3C, but the Fe-Ni-C alloy did not undergo phase transformations and preserved the original fcc structure. As a result, the alloy hardened, we could also witness a clear barometric effect: at the pressure of 2 GPa the amount of the dissolved carbon and the microhardness turned out to be significantly higher than those at 8 GPa. During sintering amorphous fullerite is undergoing phase transitions and its microhardness is higher than the microhardness of the metal component. At high temperatures of interaction graphite appears. The presence of Fe-Ni alloy in the composite reduces the temperature of graphite formation in comparison with transformations in the pure amorphous fullerene.

  16. Fluid flow sensing with ionic polymer-metal composites

    Science.gov (United States)

    Stalbaum, Tyler; Trabia, Sarah; Shen, Qi; Kim, Kwang J.

    2016-04-01

    Ionic polymer-metal composite (IPMC) actuators and sensors have been developed and modeled over the last two decades for use as soft-robotic deformable actuators and sensors. IPMC devices have been suggested for application as underwater actuators, energy harvesting devices, and medical devices such as in guided catheter insertion. Another interesting application of IPMCs in flow sensing is presented in this study. IPMC interaction with fluid flow is of interest to investigate the use of IPMC actuators as flow control devices and IPMC sensors as flow sensing devices. An organized array of IPMCs acting as interchanging sensors and actuators could potentially be designed for both flow measurement and control, providing an unparalleled tool in maritime operations. The underlying physics for this system include the IPMC ion transport and charge fundamental framework along with fluid dynamics to describe the flow around IPMCs. An experimental setup for an individual rectangular IPMC sensor with an externally controlled fluid flow has been developed to investigate this phenomenon and provide further insight into the design and application of this type of device. The results from this portion of the study include recommendations for IPMC device designs in flow control.

  17. Bio-applications of ionic polymer metal composite transducers

    Science.gov (United States)

    Aw, K. C.; McDaid, A. J.

    2014-07-01

    Traditional robotic actuators have advanced performance which in some aspects can surpass that of humans, however they are lacking when it comes to developing devices which are capable of operating together with humans. Bio-inspired transducers, for example ionic polymer metal composites (IPMC), which have similar properties to human tissue and muscle, demonstrate much future promise as candidates for replacing traditional robotic actuators in medical robotics applications. This paper outlines four biomedical robotics applications, an IPMC stepper motor, an assistive glove exoskeleton/prosthetic hand, a surgical robotic tool and a micromanipulation system. These applications have been developed using mechanical design/modelling techniques with IPMC ‘artificial muscle’ as the actuation system. The systems are designed by first simulating the performance using an IPMC model and dynamic models of the mechanical system; the appropriate advanced adaptive control schemes are then implemented to ensure that the IPMCs operate in the correct manner, robustly over time. This paper serves as an overview of the applications and concludes with some discussion on the future challenges of developing real-world IPMC applications.

  18. Modeling the cellular impact of nanoshell-based biosensors using mouse alveolar macrophage cultures.

    Science.gov (United States)

    Swarup, Vimal P; Huang, Yiming; Murillo, Genoveva; Saleiro, Diana; Mehta, Rajendra G; Bishnoi, Sandra Whaley

    2011-11-01

    In this study, the relative toxicity of native gold-silica nanoshells (NS) has been compared to nanoshells modified with poly(ethylene glycol)-thiol (PEG-SH) and a Raman-active PEG, p-mercaptoaniline-poly(ethylene glycol) (pMA-PEG), in mouse alveolar macrophage cell cultures (RAW 264.7). The results from toxicity profiling using an MTT assay demonstrate that cell viability post-particle exposure is a function of three factors: nanoshell concentration, surface functionalization, and incubation time. By minimizing particle concentrations and incubation times, cell cultures are able to recover within 24 h of nanoshell removal, indicative of nanoshells having more of a cytostatic versus cytotoxic effect on macrophage cells. The mechanism of the cytostatic effect has been investigated by imaging the presence of reactive oxygen species (ROS) using a fluorescence assay kit (Image-iT™ LIVE) after the introduction of NS to the cell cultures. Elevated ROS signals are seen in the cells containing higher concentration of NS, and indicate that the major reason of toxicity may due to the oxidative stress caused by excess NS particles. Raman imaging experiments with pMA-PEG coated nanoshells showed that cells exposed for even short exposure times (∼2 h) retained those particles up to 24 h after exposure, while migration experiments suggest that surviving cells retain their nanoshells and may reallocate them to progeny cells upon cell division.

  19. Immunoconjugated gold nanoshell-mediated photothermal ablation of trastuzumab-resistant breast cancer cells.

    Science.gov (United States)

    Carpin, Laura B; Bickford, Lissett R; Agollah, Germaine; Yu, Tse-Kuan; Schiff, Rachel; Li, Yi; Drezek, Rebekah A

    2011-01-01

    Trastuzumab is a FDA-approved drug that has shown clinical efficacy against HER2+ breast cancers and is commonly used in combination with other chemotherapeutics. However, many patients are innately resistant to trastuzumab, or will develop resistance during treatment. Alternative treatments are needed for trastuzumab-resistant patients. Here, we investigate gold nanoparticle-mediated photothermal therapies as a potential alternative treatment for chemotherapy-resistant cancers. Gold nanoshell photothermal therapy destroys the tumor cells using heat, a physical mechanism, which is able to overcome the cellular adaptations that bestow trastuzumab resistance. By adding anti-HER2 to the gold surface of the nanoshells as a targeting modality, we increase the specificity of the nanoshells for HER2+ breast cancer. Silica-gold nanoshells conjugated with anti-HER2 were incubated with both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells. Nanoshell binding was confirmed using two-photon laser scanning microscopy, and the cells were then ablated using a near-infrared laser. We demonstrate the successful targeting and ablation of trastuzumab-resistant cells using anti-HER2-conjugated silica-gold nanoshells and a near-infrared laser. This study suggests potential for applying gold nanoshell-mediated therapy to trastuzumab-resistant breast cancers in vivo.

  20. Fluorescent and cross-linked organic-inorganic hybrid nanoshells for monitoring drug delivery.

    Science.gov (United States)

    Sun, Lijuan; Liu, Tianhui; Li, Hua; Yang, Liang; Meng, Lingjie; Lu, Qinghua; Long, Jiangang

    2015-03-04

    Functionalized and monodisperse nanoshells have attracted significant attention owing to their well-defined structure, unique properties, and wide range of potential applications. Here, the synthesis of cross-linked organic-inorganic hybrid nanoshells with strong fluorescence properties was reported via a facile precipitation polymerization of hexachlorocyclotriphosphazene (HCCP) and fluorescein on silica particles used as templates. The resulting poly(cyclotriphosphazene-co-fluorescein) (PCTPF) nanoshells were firm cross-linked shells with ∼2.2 nm mesopores that facilitated the transport of drug molecules. The fluorescent nanoshells also exhibited excellent water dispersibility and biocompatibility; thus, they can be considered as ideal drug vehicles with high doxorubicin storage capacity (26.2 wt %) and excellent sustained release (up to 14 days). Compared to doxorubicin (DOX) alone, the PCTPF nanoshells more efficiently delivered DOX into and killed cancer cells. Moreover, the PCTPF nanoshells also exhibited remarkable fluorescent emission properties and improved photobleaching stability in both suspension and solid state owing to the covalent immobilization of fluorescein in the highly cross-linked organic-inorganic hybrids. The exceptional fluorescent properties enabled the release of DOX as well as the distribution of nanoshells and DOX to be monitored.

  1. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, Mariappan Parans; Liu, Hansan; Brown, Gilbert M.; Sun, Xiao-Guang; Bi, Zhonghe

    2016-12-06

    Compositions and methods of making are provided for mesoporous metal oxide microspheres electrodes. The mesoporous metal oxide microsphere compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g. The methods of making comprise forming composite powders. The methods may also comprise refluxing the composite powders in a basic solution to form an etched powder, washing the etched powder with an acid to form a hydrated metal oxide, and heat-treating the hydrated metal oxide to form mesoporous metal oxide microspheres.

  2. Hydrogen storage over alkali metal hydride and alkali metal hydroxide composites

    Institute of Scientific and Technical Information of China (English)

    Pei Yu; Yong Shen Chua; Hujun Cao; Zhitao Xiong; Guotao Wu; Ping Chen

    2014-01-01

    Alkali metal hydroxide and hydride composite systems contain both protic (H bonded with O) and hydridic hydrogen. The interaction of these two types of hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of alkali metals, i.e.,-23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150◦C; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2 , and the corresponding entropy was ca. 101.23 J/(molH2 ·K), so the temperature for releasing 1.0 bar H2 was as high as 518◦C, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be 57.87 kJ/mol, showing good kinetic properties.

  3. 'Smart' gold nanoshells for combined cancer chemotherapy and hyperthermia.

    Science.gov (United States)

    Liang, Zhongshi; Li, Xingui; Xie, Yegui; Liu, Shunying

    2014-04-01

    Nanomaterials that circulate in the body have great potential in the diagnosis and treatment of diseases. Here we report that 'smart' gold nanoshells can carry a drug payload, and that their intrinsic near-infrared (NIR) plasmon resonance enables the combination of chemotherapeutic and hyperthermia therapies. The 'smart' gold nanoshells (named DOX/A54@GNs) consist of (a) gold nanoshells (GNs) with NIR plasmon resonance, which not only act as nanoblocks but also produce local heat to allow hyperthermia; (b) an anticancer drug, doxorubicin (DOX), which was conjugated onto the nanoblocks by pH-dependent biodegradable copolymer thiol poly(ethylene glycol) derivatives via carbamate linkage; and (c) the targeting peptide A54 (AGKGTPSLETTP) to facilitate its orientation to liver cancer cells and enhance cellular uptake. The conjugated DOX was released from the DOX/A54@GNs much more rapidly in an acidic environment (pH 5.3) than in a neutral environment (pH 7.4), which is a desirable characteristic for intracellular tumor drug release. DOX-modified GNs showed pH-dependent release behavior, and the in vitro cell uptake experiment using ICP-AES and microscopy showed greater internalization of A54-modified GNs in the human liver cancer cell line BEL-7402 than of those without A54. Flow cytometry and fluoroscopy analysis were conducted to reveal the enhanced cell apoptosis caused by the A54-modified GNs under combined chemotherapeutic and hyperthermia therapies. These results imply that DOX/A54@GNs could be used as a multifunctional nanomaterial system with pH-triggered drug-releasing properties for tumor-targeted chemotherapy and hyperthermia.

  4. Multifunctional Shielding and Self-Healing HybridSil Smart Composites for Space Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has recently developed multifunctional shielding and self-healing HybridSil (HS) smart composites via the inclusion of innovative nanoshell...

  5. Hydrothermal Synthesis of Metal-Polyphenol Coordination Crystals and Their Derived Metal/N-doped Carbon Composites for Oxygen Electrocatalysis.

    Science.gov (United States)

    Wei, Jing; Liang, Yan; Hu, Yaoxin; Kong, Biao; Zhang, Jin; Gu, Qinfen; Tong, Yuping; Wang, Xianbiao; Jiang, San Ping; Wang, Huanting

    2016-09-26

    Cobalt (or iron)-polyphenol coordination polymers with crystalline frameworks are synthesized for the first time. The crystalline framework is formed by the assembly of metal ions and polyphenol followed by oxidative self-polymerization of the organic ligands (polyphenol) during hydrothermal treatment in alkaline condition. As a result, such coordination crystals are even partly stable in strong acid (such as 2 m HCl). The metal (Co or Fe)-natural abundant polyphenol (tannin) coordination crystals are a renewable source for the fabrication of metal/carbon composites as a nonprecious-metal catalyst, which show high catalytic performance for both oxygen reduction reaction and oxygen evolution reaction. Such excellent performance makes metal-polyphenol coordination crystals an efficient precursor to fabricate low-cost catalysts for the large-scale application of fuel cells and metal-air batteries.

  6. Heavy metal and proximate composition associated with the ...

    African Journals Online (AJOL)

    User

    2014-05-08

    May 8, 2014 ... inorganic products, generating heat as a metabolic waste product. Heavy metal ..... Potencial Bioremediation Agent in Compost Material Contaminated with Heavy .... Toxicity of non-radioactive heavy metals and their salts in ...

  7. Investigation into the role of NaOH and calcium ions in the synthesis of calcium phosphate nanoshells

    Directory of Open Access Journals (Sweden)

    C. H. Yeo

    2012-03-01

    Full Text Available Calcium phosphate (CaP nanoshells were prepared using negatively charged liposomes (1,2-dioleoyl-sn-glycero-3-phosphate sodium salt (DOPA as a template by base titration synthesis at various concentrations of NaOH and calcium ions. The elemental composition, morphology, particle size, particle size distribution and zeta potential of the products were determined via various characterisation techniques, such as energy-dispersive X-ray spectrometry (EDX, transmission electron microscopy (TEM, dynamic light scattering (DLS, laser Doppler velocimetry (LDV and Fourier transform infrared spectroscopy (FTIR. The best results showed that stable spherical CaP nanoshells with a mean particle size of 197.5 ± 5.8 nm and a zeta potential of -34.5 ± 0.6 mV were successfully formed when 0.100 M sodium hydroxide (NaOH and 0.100 M calcium ions were used. Moreover, an optimal pH of 10.52 and a final Ca/P molar ratio of 0.97 were achieved under these conditions.

  8. Size-dependent transformation from Ag templates to Au-Ag nanoshells via galvanic replacement reaction in organic medium

    Energy Technology Data Exchange (ETDEWEB)

    Karvianto; Chow, G. M., E-mail: msecgm@nus.edu.sg [National University of Singapore, Department of Materials Science and Engineering (Singapore)

    2012-10-15

    The transformation from Ag templates to Au-Ag nanoshells via galvanic replacement reaction with HAuCl{sub 4} was systematically studied in an organic medium in the presence of oleylamine. Decahedral ({approx}43 nm in size) and triangular prism ({approx}53 nm in edge length) Ag templates transformed into equiaxed and triangular prismatic Au-Ag nanoshells, respectively. The first step involved structural and morphological changes from Ag templates to Au-Ag nanoshells with an interior cavity. In the second step, the growth of the shells continued through the deposition of Au. The shell thickness increased from {approx}5 to {approx}10 nm for the equiaxed Au-Ag nanoshells ({approx}39-nm interior cavity) and {approx}5 to {approx}8 nm for the triangular prismatic Au-Ag nanoshells ({approx}52-nm interior edge length). Oleylamine not only served as a surfactant but also removed AgCl precipitates and reduced HAuCl{sub 4}. For the nanoshells derived from the {approx}20-nm Ag decahedrons, further reaction in excess HAuCl{sub 4} collapsed the nanoshells into Au-rich solid fragments. However, the nanoshells derived from the {approx}43-nm Ag decahedrons, the nanoshell structure not only persisted in excess HAuCl{sub 4}, but its shell thickness also increased. The size-dependent transformation of these nanoshells is discussed.

  9. Narrow optical filtering with plasmonic nanoshells

    CERN Document Server

    Martynov, Y B; Tanachev, I A; Gladyshev, P P

    2011-01-01

    Narrow optical band pass filters are widely used in systems with optical processing of information, color displays development and optical computers. We show that such ultra filters can be created by means of nanoparticles which consist of a dielectric sphere and a metallic shell. The components can be adjusted such that there is a remarkable transparency at the desired wavelength range, while a strong absorption takes place outside of this region.

  10. Electromagnetic energy transport in a chain waveguide of silver nanoshell cylinder array

    Science.gov (United States)

    Jacob, Jesly; Ajith, R.; Mathew, Vincent

    2013-08-01

    Plasmonic wave propagation in a chain waveguide created by a triangular array of silver nanoshell cylinder was investigated using finite element method and Finite Difference Time Domain Method. It is observed that the trimer nanoshell cylinder array provides better field propagation compared to single-chain and pair-chain nanoshell cylinder arrays. Results show that the resonant wavelength of the structure is highly sensitive to the permittivity of either the core or the surrounding medium. It is also observed that as the core thickness of the waveguide is increased surface plasmon resonance shows a red shift.

  11. Laser-induced thermal dynamics and temperature localization phenomenon in tissues and cells doped with nanoshells

    Science.gov (United States)

    Yakunin, Alexander N.; Avetisyan, Yury A.; Tuchin, Valery V.

    2012-03-01

    Paper presents and discusses the features of laser-induced thermal dynamics of the gold nanoshells, which is associated with their relatively large size and layered structure. Unlike bulk nanoparticles the existence of a novel thermal phenomenon - hoop-shaped narrow hot zone on the nanoshell surface - is found. It is caused by spatial-temporal inhomogeneities of light field diffracted by a nanoshell and corresponding absorption of laser radiation. The numerical solution of time-dependent heat conduction equation accounting for corresponding spatially inhomogeneous distribution of heating sources is presented.

  12. Reaction mechanisms and microstructures of ceramic-metal composites made by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Fahrenholtz, W.F. [Univ. of New Mexico, Albuquerque, NM (United States). Advanced Materials Lab.; Ewsuk, K.G.; Loehman, R.E. [Sandia National Labs., NM (United States)] [and others

    1996-12-31

    Ceramic-metal composites can be made by reactive penetration of molten metals into dense ceramic performs. The metal penetration is driven by a large negative Gibbs energy for reaction, which is different from the more common physical infiltration of porous media. Reactions involving Al can be written generally as (x+2)Al + (3/y)MO{sub y} {yields} Al{sub 2}O{sub 3} + M{sub 3/y}Al{sub x}, where MO{sub y} is an oxide that is wet by molten Al. In low Po{sub 2} atmospheres and at temperature above about 900{degrees}c, molten Al reduces mullite to produce Al{sub 2}O{sub 3} + M{sub 3/y}Al{sub x}, where MO is an oxide that is wet by molten Al. In low Po{sub 2} atmospheres and at temperatures above about 900{degrees}C, molten al reduces mullite to produce Al{sub 2}O{sub 3} and Si. The Al/mullite reaction has a {Delta}G{sub r}{degrees} (1200K) of -1014 kJ/mol and, if the mullite is fully dense, the theoretical volume change on reaction is less than 1%. A microstructure of mutually-interpenetrating metal and ceramic phases generally is obtained. Penetration rate increases with increasing reaction temperature from 900 to 1150{degrees}C, and the reaction layer thickness increases linearly with time. Reaction rate is a maximum at 1150{degrees}C; above that temperature the reaction slows and stops after a relatively short period of linear growth. At 1300{degrees}C and above, no reaction layer is detected by optical microscopy. Observations of the reaction front by TEM show only al and Al{sub 2}O{sub 3} after reaction at 900{degrees}C, but Si is present in increasing amounts as the reaction temperature increases to 1100{degrees}C and above. The kinetic and microstructural data suggest that the deviation from linear growth kinetics at higher reaction temperatures and longer times is due to Si build-up and saturation at the reaction front. The activation energy for short reaction times at 900 to 1150{degrees}C varies from {approximately}90 to {approximately}200 kJ/mole.

  13. GENERATION OF A COMPOSITE GLASS-METAL ROD: PRACTICAL RESULTS

    Directory of Open Access Journals (Sweden)

    Gridasova Ekaterina Alexandrovna

    2012-10-01

    Full Text Available Glass has a high compressive strength and low impact strength. The strength of glass in compression is a lot higher than the strength of glass in tension, and it varies within the range of 500-1,250 MPa. Whenever the glass is in compression, it can compete with the properties of metal in terms of its strength. The tensile strength of glass under tension is 30-50 MPa. The reason for that is the fact that the strength of glass is strongly dependent on the state of its surface. Methods of increasing the strength of glass have been the subject of research projects implemented at Far Eastern Federal University. The objective is to apply compressive stresses that would prevent any defects in the surface layer and harden the surface to improve the glass resistance to mechanical stresses and isolate it from the environment. Creation of a composite rod made of glass grade C49-1 (3С5Na and steel E235C (ISO standard manufactured through the employment of diffusion bonding represents a practical result of the research. Its analysis has proven the presence of full contact, absence of cracks and poor penetration alongside the welding zone. Microscopy methods of analysis have demonstrated the presence of the transition zone in the points of interface of materials. The results of the spectral analysis prove the penetration of Fe-cations into the glass down to the depth of 30 microns. The chemical analysis of the zone of diffusion proves that the crystalline structure, or fayalite (Fe2SiO4, is formed in the glass. The rod strength analysis has demonstrated its high compressive

  14. SERS biodetection using gold-silica nanoshells and nitrocellulose membranes.

    Science.gov (United States)

    Bishnoi, Sandra Whaley; Lin, Yu-jen; Tibudan, Martin; Huang, Yiming; Nakaema, Marcelo; Swarup, Vimal; Keiderling, Timothy A

    2011-06-01

    We have developed a rapid, reproducible, easy to execute, surface enhanced Raman scattering (SERS) method for detection of low volumes and total amounts of biological antigens using an analyte capture system derived from methods commonly used in Western blotting. Our method is a "half-sandwich" assay with an antigen detection scheme that employs a nitrocellulose (NC) membrane with 200 nm pore size to capture subnanograms of analyte and concentrate them in a small area from applied volumes as low as one microliter. The SERS probes used for detection consist of gold-silica nanoshells modified with a two-component mixed monolayer system. One component consists of a poly(ethylene glycol) (PEG)-modified Raman-active chromophore bound to the gold surface which allows for SERS detection and imparts particle stability. The second component uses (ortho-pyridyl) disulfide-PEG-succinimidyl ester to couple the recognition antibody to the particle surface. By controlling the reaction time and concentration of thiols, a mixed monolayer is prepared on the nanoshell surface with the ability to recognize low concentrations of analyte and generate reproducible SERS signals. Using this strategy, we have achieved SERS signals that are proportional to antigen present on the membrane allowing detection of total antigen amounts as low as 1.25 ng for some cases. The performance of this new SERS bioassay has been tested with a variety of potential antigens, demonstrating the potential for multiplexed detection of analytes.

  15. Narrow band imaging of tumors using gold nanoshells

    Science.gov (United States)

    Puvanakrishnan, Priyaveena; Park, Jaesook; Diagaradjane, Parameshwaran; Schwartz, Jon A.; Coleman, Chris L.; Gill-Sharp, Kelly L.; Sang, Kristina L.; Payne, J. Donald; Krishnan, Sunil; Tunnell, James W.

    2009-02-01

    Gold nanoshells (GNS) are a new class of nanoparticles that can be optically tuned to scatter or absorb light from the near-ultraviolet to near-infrared (NIR) region by varying the core (dielectric silica) /shell (gold) ratio. In addition to spectral tunability, GNS are inert and bioconjugatable making them potential labels for in vivo imaging and therapy of tumors. We report the use of GNS as exogenous contrast agents for enhanced visualization of tumors using narrow band imaging (NBI). NBI takes advantage of the strong NIR absorption of GNS to distinguish between blood and nanoshells in the tumor by imaging in narrow wavelength bands in the visible and NIR, respectively. Using tissue-simulating phantoms, we determined the optimum wavelengths to enhance contrast between blood and GNS. We then used the optimum wavelengths for ex-vivo imaging of tumors extracted from human colon cancer xenograft bearing mice injected with GNS. Systemically delivered GNS accumulated passively in tumor xenografts by the enhanced permeability and retention (EPR) effect. Ex-vivo NBI of tumor xenografts demonstrated tumor specific heterogeneous distribution of GNS with a clear distinction from the tumor vasculature. The results of this study demonstrate the feasibility of using GNS as contrast agents to visualize tumors using NBI.

  16. Automated Design and Analysis Tool for CLV/CEV Composite and Metallic Structural Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation of the proposed effort is a unique automated process for the analysis, design, and sizing of CLV/CEV composite and metallic structures. This developed...

  17. Design and Analysis of Metal-to-Composite Nozzle Extension Joints Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the operational demands of liquid rocket engines increases, so too does the need for improved design and manufacturing methods for metal-to-composite nozzle...

  18. Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Aslam, Muhammad, E-mail: klaira73@gmail.com; Altaf, Khurram, E-mail: khurram.altaf@petronas.com.my; Shirazi, Irfan, E-mail: irfanshirazi@hotmail.com [Mechanical Engineering Universiti Teknologi PETRONAS Malaysia (Malaysia)

    2015-07-22

    Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Random orientation of fibers was noted in the composites test bars produced from divergent melt flow.

  19. PHASE CONVERSIONS IN METAL-OXIDE COMPOSITIONS ON THE BASIS OF ALUMINIUM AND SILICON OXIDE

    OpenAIRE

    2010-01-01

    The regularities of phase conversions in metal-oxide compositions on the basis of aluminium and silicon oxide with the purpose of silumins synthesis by means of direct restoration of aluminium silicon are studied.

  20. Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-05-20

    An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

  1. Fatigue resistance and failure mode of adhesively restored custom metal-composite resin premolar implant abutments.

    Science.gov (United States)

    Boff, Luís Leonildo; Oderich, Elisa; Cardoso, Antônio Carlos; Magne, Pascal

    2014-01-01

    To evaluate the fatigue resistance and failure mode of composite resin and porcelain onlays and crowns bonded to premolar custom metal-composite resin premolar implant abutments. Sixty composite resin mesostructures were fabricated with computer assistance with two preparation designs (crown vs onlay) and bonded to a metal implant abutment. Following insertion into an implant with a tapered abutment interface (Titamax CM), each metal-composite resin abutment was restored with either composite resin (Paradigm MZ100) or ceramic (Paradigm C) (n = 15) and attached with adhesive resin (Optibond FL) and a preheated light-curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was then simulated, starting with 5,000 cycles at a load of 50 N, followed by stages of 200, 400, 600, 800, 1,000, 1,200, and 1,400 N (25,000 cycles each). Samples were loaded until fracture or to a maximum of 180,000 cycles. The four groups were compared using life table survival analysis (log-rank test). Previously published data using zirconia abutments of the same design were included for comparison. Paradigm C and MZ100 specimens fractured at average loads of 1,133 N and 1,266 N, respectively. Survival rates ranged from 20% to 33.3% (ceramic crowns and onlays) to 60% (composite resin crowns and onlays) and were significantly different (pooled data for restorative material). There were no restoration failures, but there were adhesive failures at the connection between the abutment and the mesostructure. The survival of the metal-composite resin premolar abutments was inferior to that of identical zirconia abutments from a previous study (pooled data for abutment material). Composite resin onlays/crowns bonded to metal-composite resin premolar implant abutments presented higher survival rates than comparable ceramic onlays/crowns. Zirconia abutments outperformed the metal-composite resin premolar abutments.

  2. Rheology in Processing of in Situ Composites of Polypropylene and Low Melting Poing Metals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The low melting point metallic tin powder or alloy of tin and lead was blended with polypropylene. A kind of in situ composite has been prepared.The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ composites of the low melting point metals (LMPM) and coupling agent for their different variety and content,were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted,the higher the content of the LMPM, the lower apparent viscosity of composites.Meanwhile,when the coupling agent is added into composites,the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene.

  3. Production and mechanical properties of Al-SiC metal matrix composites

    Science.gov (United States)

    Karvanis, K.; Fasnakis, D.; Maropoulos, A.; Papanikolaou, S.

    2016-11-01

    The usage of Al-SiC Metal Matrix Composites is constantly increasing in the last years due to their unique properties such as light weight, high strength, high specific modulus, high fatigue strength, high hardness and low density. Al-SiC composites of various carbide compositions were produced using a centrifugal casting machine. The mechanical properties, tensile and compression strength, hardness and drop-weight impact strength were studied in order to determine the optimum carbide % in the metal matrix composites. Scanning electron microscopy was used to study the microstructure-property correlation. It was observed that the tensile and the compressive strength of the composites increased as the proportion of silicon carbide became higher in the composites. Also with increasing proportion of silicon carbide in the composite, the material became harder and appeared to have smaller values for total displacement and total energy during impact testing.

  4. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

    OpenAIRE

    Mazhorova, Anna; Gu, Jian Feng; Dupuis, Alexandre; Tsuneyuki, Ozaki; Paccianti, Marco; Morandotti, Roberto; MINAMIDE, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-01-01

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0....

  5. Nanomodeling of Nonlinear Thermoelastic Behavior of AA5454/ Silicon Nitride Nanoparticulate Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Chennakesava R Alavala

    2016-01-01

    Full Text Available The aim of the present work was to estimate non-linear thermoelastic behavior of three-phase AA5454/silicon nitride nanoparticle metal matrix composites. The thermal loading was varied from subzero temperature to under recrystallization temperature. The RVE models were used to analyze thermo-elastic behavior. The AA5454/silicon nitride nanoparticle metal matrix composites have gained the elastic modulus below 0oC and lost at high temperatures.

  6. The Effect of Thermomechanical Processing on Mechanical Properties of a Cast 6061 Aluminum Metal Matrix Composite

    Science.gov (United States)

    1993-12-01

    Conference Proceedings, 1990 19. Lewandowski, J. J. et al., "Effects of Casting Conditions and Deformation Processing on A356 Aluminum and A356 -20 Vol...CAST 6061 ALUMINUM METAL MATRIX COMPOSITE by Werner Fletcher Hoyt December 1993 Thesis Advisor: Terry R. McNelley Approved for public release...Security Classification) THE EFFECT OF THERMOMECHANICAL PROCESSING ON MECHANICAL PROPERTIES OF A CAST 6061 ALUMINUM METAL MATRIX COMPOSITE 12. PERSONAL

  7. EphrinA1-targeted nanoshells for photothermal ablation of prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Andre M Gobin

    2008-10-01

    Full Text Available Andre M Gobin, James J Moon, Jennifer L WestDepartment of Bioengineering, Rice University, Houston, TX, USAAbstract: Gold-coated silica nanoshells are a class of nanoparticles that can be designed to possess strong absorption of light in the near infrared (NIR wavelength region. When injected intravenously, these nanoshells have been shown to accumulate in tumors and subsequently mediate photothermal treatment, leading to tumor regression. In this work, we sought to improve their specificity by targeting them to prostate tumor cells. We report selective targeting of PC-3 cells with nanoshells conjugated to ephrinA1, a ligand for EphA2 receptor that is overexpressed on PC-3 cells. We demonstrate selective photo-thermal destruction of these cells upon application of the NIR laser.Keywords: nanoshell, near infrared, photothermal treatment, prostate cancer

  8. Nanoshells for in vivo imaging using two-photon excitation microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gao Liang; Nammalvar, Vengadesan [Department of Bioengineering, Rice University, Houston, TX 77005 (United States); Vadakkan, Tegy J, E-mail: lg3@rice.edu, E-mail: venkyn@rice.edu [Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030 (United States)

    2011-09-07

    Gold nanoshells have been intensively investigated and applied to various biomedical fields because of their flexible optical tunability and biological compatibility. They hold great potential to serve as luminescent contrast agents excitable with near-infrared (NIR) lasers. In this paper, we describe the development of nanoshells with a peak of plasmon resonance at 800 nm and their subsequent use for in vivo blood vessel imaging using two-photon excitation microscopy at an excitation wavelength of 750 nm. We were able to image single nanoshell particles in blood vessels and generate optical contrast for blood vessel structure using luminescent signals. These results confirm the feasibility of engineering nanoshells with controlled optical properties for single-particle-based in vivo imaging.

  9. Nanoshells for in vivo imaging using two-photon excitation microscopy.

    Science.gov (United States)

    Gao, Liang; Vadakkan, Tegy J; Nammalvar, Vengadesan

    2011-09-07

    Gold nanoshells have been intensively investigated and applied to various biomedical fields because of their flexible optical tunability and biological compatibility. They hold great potential to serve as luminescent contrast agents excitable with near-infrared (NIR) lasers. In this paper, we describe the development of nanoshells with a peak of plasmon resonance at 800 nm and their subsequent use for in vivo blood vessel imaging using two-photon excitation microscopy at an excitation wavelength of 750 nm. We were able to image single nanoshell particles in blood vessels and generate optical contrast for blood vessel structure using luminescent signals. These results confirm the feasibility of engineering nanoshells with controlled optical properties for single-particle-based in vivo imaging.

  10. Metal- and Polymer-Matrix Composites: Functional Lightweight Materials for High-Performance Structures

    Science.gov (United States)

    Gupta, Nikhil; Paramsothy, Muralidharan

    2014-06-01

    The special topic "Metal- and Polymer-Matrix Composites" is intended to capture the state of the art in the research and practice of functional composites. The current set of articles related to metal-matrix composites includes reviews on functionalities such as self-healing, self-lubricating, and self-cleaning capabilities; research results on a variety of aluminum-matrix composites; and investigations on advanced composites manufacturing methods. In addition, the processing and properties of carbon nanotube-reinforced polymer-matrix composites and adhesive bonding of laminated composites are discussed. The literature on functional metal-matrix composites is relatively scarce compared to functional polymer-matrix composites. The demand for lightweight composites in the transportation sector is fueling the rapid development in this field, which is captured in the current set of articles. The possibility of simultaneously tailoring several desired properties is attractive but very challenging, and it requires significant advancements in the science and technology of composite materials. The progress captured in the current set of articles shows promise for developing materials that seem capable of moving this field from laboratory-scale prototypes to actual industrial applications.

  11. Weld microstructure in cast AlSi9/SiC(p metal matrix composites

    Directory of Open Access Journals (Sweden)

    J. Wysocki

    2009-04-01

    Full Text Available Welded joint in cast AlSi9/SiC/20(p metal matrix composite by manual TIG arc welding using AlMg5 filler metal has been described inhis paper. Cooling curves have been stated, and the influence in distribution of reinforced particles on crystallization and weldmicrostructure. Welded joint mechanical properties have been determined: hardness and tensile.

  12. Microwave Absorbing Properties of Metallic Glass/Polymer Composites

    Science.gov (United States)

    2011-09-01

    of strategic importance for stealth technology. This work examined high magnetic permeability cobalt -based metallic glasses dispersed in epoxy...of strategic importance for stealth technology. This work examined high magnetic permeability cobalt -based metallic glasses dispersed in epoxy...present day. Lossy materials such as carbonyl iron and ferrites have been used in stealth technology as well as other electromagnetic shielding

  13. REMOVAL OF CERTAIN FISSION PRODUCT METALS FROM LIQUID BISMUTH COMPOSITIONS

    Science.gov (United States)

    Dwyer, O.E.; Howe, H.E.; Avrutik, E.R.

    1959-11-24

    A method is described for purifying a solution of urarium in liquid bismuth containing at least one metal from the group consisting of selenium, tellurium, palladium, ruthenium, rhodium, niobium, and zirconium. The solution is contacted with zinc in an inert atmosphere to form a homogeneous melt, a solid zinc phase is formed, and the zinc phase containing the metal is separated from the melt.

  14. Nanoshell-mediated photothermal therapy improves survival in a murine glioma model.

    Science.gov (United States)

    Day, Emily S; Thompson, Patrick A; Zhang, Linna; Lewinski, Nastassja A; Ahmed, Nabil; Drezek, Rebekah A; Blaney, Susan M; West, Jennifer L

    2011-08-01

    We are developing a novel treatment for high-grade gliomas using near infrared-absorbing silica-gold nanoshells that are thermally activated upon exposure to a near infrared laser, thereby irreversibly damaging cancerous cells. The goal of this work was to determine the efficacy of nanoshell-mediated photothermal therapy in vivo in murine xenograft models. Tumors were induced in male IcrTac:ICR-Prkdc(SCID) mice by subcutaneous implantation of Firefly Luciferase-labeled U373 human glioma cells and biodistribution and survival studies were performed. To evaluate nanoparticle biodistribution, nanoshells were delivered intravenously to tumor-bearing mice and after 6, 24, or 48 h the tumor, liver, spleen, brain, muscle, and blood were assessed for gold content by inductively coupled plasma-mass spectrometry (ICP-MS) and histology. Nanoshell concentrations in the tumor increased for the first 24 h and stabilized thereafter. Treatment efficacy was evaluated by delivering saline or nanoshells intravenously and externally irradiating tumors with a near infrared laser 24 h post-injection. Success of treatment was assessed by monitoring tumor size, tumor luminescence, and survival time of the mice following laser irradiation. There was a significant improvement in survival for the nanoshell treatment group versus the control (P nanoshell treatment group remained tumor free at the end of the 90-day study period. By comparison, none of the mice in the control group survived beyond 24 days and mean survival was only 13.3 days. The results of these studies suggest that nanoshell-mediated photothermal therapy represents a promising novel treatment strategy for malignant glioma.

  15. Nanoshell-mediated photothermal therapy can enhance chemotherapy in inflammatory breast cancer cells

    OpenAIRE

    Fay BL; Melamed JR; Day ES

    2015-01-01

    Brittany L Fay, Jilian R Melamed, Emily S Day Biomedical Engineering, University of Delaware, Newark, DE, USA Abstract: Nanoshell-mediated photothermal therapy (PTT) is currently being investigated as a standalone therapy for the treatment of cancer. The cellular effects of PTT include loss of membrane integrity, so we hypothesized that nanoshell-mediated PTT could potentiate the cytotoxicity of chemotherapy by improving drug accumulation in cancer cells. In this work, we validated our hypo...

  16. Machinability of titanium metal matrix composites (Ti-MMCs)

    Science.gov (United States)

    Aramesh, Maryam

    Titanium metal matrix composites (Ti-MMCs), as a new generation of materials, have various potential applications in aerospace and automotive industries. The presence of ceramic particles enhances the physical and mechanical properties of the alloy matrix. However, the hard and abrasive nature of these particles causes various issues in the field of their machinability. Severe tool wear and short tool life are the most important drawbacks of machining this class of materials. There is very limited work in the literature regarding the machinability of this class of materials especially in the area of tool life estimation and tool wear. By far, polycrystalline diamond (PCD) tools appear to be the best choice for machining MMCs from researchers' point of view. However, due to their high cost, economical alternatives are sought. Cubic boron nitride (CBN) inserts, as the second hardest available tools, show superior characteristics such as great wear resistance, high hardness at elevated temperatures, a low coefficient of friction and a high melting point. Yet, so far CBN tools have not been studied during machining of Ti-MMCs. In this study, a comprehensive study has been performed to explore the tool wear mechanisms of CBN inserts during turning of Ti-MMCs. The unique morphology of the worn faces of the tools was investigated for the first time, which led to new insights in the identification of chemical wear mechanisms during machining of Ti-MMCs. Utilizing the full tool life capacity of cutting tools is also very crucial, due to the considerable costs associated with suboptimal replacement of tools. This strongly motivates development of a reliable model for tool life estimation under any cutting conditions. In this study, a novel model based on the survival analysis methodology is developed to estimate the progressive states of tool wear under any cutting conditions during machining of Ti-MMCs. This statistical model takes into account the machining time in

  17. Selective Catalysis in Nanoparticle Metal-Organic Framework Composites

    Science.gov (United States)

    Stephenson, Casey Justin

    The design of highly selective catalysts are becoming increasingly important, especially as chemical and pharmaceutical industries seek to improve atom economy and minimize energy intensive separations that are often required to separate side products from the desired product. Enzymes are among the most selective of all catalysts, generally operating through molecular recognition whereby an active site analogous to a lock and the substrate is analogous to a key. The assembly of a porous, crystalline material around a catalytically active metal particle could serve as an artificial enzyme. In this vein, we first synthesized the polyvinylpyrrolidone (PVP) coated nanoparticles of interest and then encapsulated them within zeolitic imidazolate framework 8 or ZIF-8. 2.8 nm Pt-PVP nanoparticles, which were encapsulated within ZIF-8 to form Pt ZIF-8 composite. Pt ZIF-8 was inactive for the hydrogenation of cyclic olefins such as cis-cyclooctene and cis-cyclohexene while the composite proved to be a highly selective catalyst for the hydrogenation of terminal olefins, hydrogenating trans-1,3-hexadiene to 3-hexene in 95% selectivity after 24 hours under 1 bar H2. We extended our encapsulation method to sub-2 nm Au nanoparticles to form Au ZIF-8. Au ZIF-8 served as a highly chemoselective catalyst for the hydrogenation of crotonaldehyde an alpha,beta-unsaturated aldehyde, to crotyl alcohol an alpha,beta-unsaturated alcohol, in 90-95% selectivity. In order to investigate nanoparticle size effects on selectivity, 6-10 nm Au nanoparticles were encapsulated within ZIF-8 to form Au6 ZIF-8. Control catalysts with nanoparticles supported on the surface of ZIF-8 were synthesized as well, Au/ZIF-8 and Au6/ZIF-8. Au6 ZIF-8 hydrogenated crotonaldehyde in 85% selectivity towards the unsaturated alcohol. Catalysts with nanoparticles supported on the exterior of ZIF-8 were far less selective towards the unsaturated alcohol. Post-catalysis transmission electron microscopy analysis of Au ZIF

  18. Axial interface optical phonon modes in a double-nanoshell system

    Energy Technology Data Exchange (ETDEWEB)

    Kanyinda-Malu, C; Clares, F J; Cruz, R M de la [Departamento de Fisica, Universidad Carlos III de Madrid, EPS Avenida de la Universidad 30, 28911 Leganes (Madrid) (Spain)], E-mail: clement.kanyindamalu@urjc.es, E-mail: rmc@fis.uc3m.es

    2008-07-16

    Within the framework of the dielectric continuum (DC) model, we analyze the axial interface optical phonon modes in a double system of nanoshells. This system is constituted by two identical equidistant nanoshells which are embedded in an insulating medium. To illustrate our results, typical II-VI semiconductors are used as constitutive polar materials of the nanoshells. Resolution of Laplace's equation in bispherical coordinates for the potentials derived from the interface vibration modes is made. By imposing the usual electrostatic boundary conditions at the surfaces of the two-nanoshell system, recursion relations for the coefficients appearing in the potentials are obtained, which entails infinite matrices. The problem of deriving the interface frequencies is reduced to the eigenvalue problem on infinite matrices. A truncating method for these matrices is used to obtain the interface phonon branches. Dependences of the interface frequencies on the ratio of inter-nanoshell separation to core size are obtained for different systems with several values of nanoshell interdistance. Effects due to the change of shell and embedding materials are also investigated in interface phonon modes.

  19. Flexible Ceramic-Metal Insulation Composite and Method of Making

    Science.gov (United States)

    Rasky, Daniel J. (Inventor); Sawko, Paul M. (Inventor); Kilodziej, Paul (Inventor); Kourtides, Demetrius A. (Inventor)

    1998-01-01

    A method for joining a woven flexible ceramic fabric and a thin metal sheet creating an integral metal surfaced flexible thermal protection article, which methods compress: placing multiple dots of high temperature metallic or fabric and the thin metal sheet in a random or organized pattern, with the proviso that the brazing material covers about 10% or less of the surface of one flat side of the metal sheet; heating the flexible ceramic fabric, brazing material and thin metal sheet for a predetermined period of time to integrally connect the same; and cooling the formed flexible article to ambient temperature. Preferably the flexible ceramic is selected from fibers comprising atoms of silicon, carbon, nitrogen, boron, oxygen or combinations thereof. The flexible thermal protection article produced is also part of the present invention. The thin metal sheet is comprised of titanium, aluminum, chromium, niobium or alloys or combinations thereof. The brazing material is selected from copper/silver or copper/gold or is a ceramic brazing or adhesive material.

  20. Simulations of light scattering spectra of a nanoshell on plane interface based on the discrete sources method

    Science.gov (United States)

    Eremina, Elena; Eremin, Yuri; Wriedt, Thomas

    2006-11-01

    The resonance properties of nanoshells are of great interest in nanosensing applications such as surface enhanced Raman scattering or biological sensing. In this paper the discrete sources method has been applied to analyze the spectrum of evanescent light scattering from a nanoshell particle deposited near a plane surface. Based on the rigorous theoretical model, which allows to take into account all features of the scattering problem as: medium with frequency dispersion, presence of the interface, the objective aperture and its location and core-shell asphericity, the scattering spectrum of nanoshells was calculated. The dependence of the local nanoshell spectral density behavior on its properties is discussed.

  1. Preparation and properties of metal-PVA composite hydrophilic ultrafiltration membranes

    Institute of Scientific and Technical Information of China (English)

    邱运仁; 张启修

    2003-01-01

    Metal-polyvinyl alcohol(PVA) composite ultrafiltration membranes were prepared by coating a certain concentration of PVA solution on metallic fiber sintered membranes. The effects of preparation conditions, such as the coating solution concentration, sequence and times of coating, and heat-treatment on the properties of the composite membranes were studied. The results show that the hole diameter of the composite membrane decreases with the increase of the concentration of PVA, the hole diameter of composite membrane is different when the sequence of coating is different. When the higher concentration of PVA solution is used to coat the metallic membrane for the first time and the other smaller one for the second time, the hole diameter of the composite membrane is relatively small, compared with that of the composite membrane made by the smaller concentration of PVA solution for the first time and the other higher one for the second time. The holes of the composite membrane contract and the stability of the membrane is improved by heat treatment. When metal-PVA composite hydrophilic membranes are used to treat the oil/water emulsion with the concentration of 1 000 mg@ L -1, the retention is from 80% to 90%, and the permeate flux is from 15 L @ m-2 @ h-1 to 40 L @ m-2 @ h-1 at pressure of 0.2 to 0.3 MPa.

  2. Using thin metal layers on composite structures for shielding the electromagnetic pulse caused by nearby lightning

    NARCIS (Netherlands)

    Blaj, M.A.; Buesink, F.J.K.; Damstra, G.C.; Leferink, F.B.J.

    2011-01-01

    Electronic systems in composite structures could be vulnerable to the (dominant magnetic) field caused by a lightning strike, because only thin layers of metal can be used on composite structures. Thin layers result in a very low shielding effectiveness against magnetic fields. Many experiments usin

  3. Highly enhanced spontaneous emission with nanoshell-based metallodielectric hybrid antennas

    Science.gov (United States)

    Cheng, Yuqing; Lu, Guowei; shen, Hongming; Wang, Yuwei; He, Yingbo; Chou, R. Yuanying; Gong, Qihuang

    2015-09-01

    The metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance spontaneous emission greatly rather than the individual spherical nanoparticle. Moreover, the performances of the hybrid antenna can be boosted further through using asymmetrical nanoshell. The mechanism of the high enhancement effect is due to the hybrid structure being able to couple efficiently with the electric field by a larger dipolar moment. And the emission directivity of the hybrid antenna is able to be modified by adjusting the geometry of the plasmonic nanostructures. The results should be beneficial for various fundamental and applied research fields, including single molecule fluorescence and surface enhance Raman spectroscopy, etc. The enhancement of spontaneous emission is in demand in fundamental interests and various applied research fields. However, the electromagnetic enhancement of single plasmonic nanostructure is limited due to intrinsic loss of metal materials and quantum tunneling effect which also limits the ability of enhancement of spontaneous emission. Interestingly, it was found that hybrid structures can provide higher enhancement effect. This study is about a kind new type of optical antenna to control spontaneous emission of single emitter, i.e. a metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate which can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance

  4. Toward superlensing with metal-dielectric composites and multilayers

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Bundgaard; Thoreson, M.D.; Chen, W.;

    2010-01-01

    We report on the fabrication of two types of adjustable, near-field superlens designs: metal–dielectric composites and metal–dielectric multilayer films. We fabricated a variety of films with different materials, thicknesses and compositions. These samples were characterized physically...... and optically to determine their film composition, quality, and optical responses. Our results on metal–dielectric composites indicate that although the real part of the effective permittivity generally follows effective medium theory predictions, the imaginary part does not and substantially higher losses...

  5. Preparation of SiCp/Al2O3-Al Composites by Directed Metal Oxidation

    Institute of Scientific and Technical Information of China (English)

    LIN Ying; YANG Hai-bo; WANG Fen; ZHU Jian-feng

    2006-01-01

    SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.

  6. Preparation of Chitosan/Polystyrene Sulfonate Multilayered Composite Metal Nanoparticles and Its Application.

    Science.gov (United States)

    Xiong, Fangxin; Chen, Chunxiao; Liu, Shantang

    2016-06-01

    Metal-Chitosan (CTS) composite was first synthesized through the metal composition of chitosan (CTS) and metal ions. The formed composite was alternately deposited on the base with sodium polystyrene sulfonate (PSS) through a layer-by-layer self-assembling technique, followed by an in situ reduction by sodium borohydride to produce a polyelectrolyte nanocomposite thin film containing metal nanoparticles. Assembly, surface morphology and electrochemical properties of the composite membrane were analyzed by UV-visible absorption spectroscopy (UV-vis), atomic force microscopy (AFM) and cyclic voltammetry (CV). The UV-Vis results indicated that the absorbance of the multilayer film at the characteristic absorption peak increased as the membrane bilayers increased, in a good linear relationship, which demonstrated that the multilayer film was uniformly assembled on the base. AFM images showed that the surface of the multilayer thin-film composite had some degree of roughness and metal nanoparticles of 10-20 nm in size were generated on the membrane. The CV results indicated that the metal nanocomposite film had excellent electrocatalytic activity to glucose and had a potential for applications in electrochemical sensors.

  7. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    KAUST Repository

    Chen, Ye

    2017-01-26

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets. The composition has high conductivity and flexibility. The composition can be made by a one-pot synthesis in which a graphene material precursor is converted to the graphene material, and the metal precursor is converted to the metal. A reducing solvent or dispersant such as NMP can be used. Devices made from the composition include a pressure sensor which has high sensitivity. Two two- dimension materials can be combined to form a hybrid material.

  8. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

    CERN Document Server

    Mazhorova, Anna; Dupuis, Alexandre; Tsuneyuki, Ozaki; Paccianti, Marco; Morandotti, Roberto; Minamide, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-01-01

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. We then detail the selfconsistent algorithm for retrieving the optical properties of the metal alloy used in the fabrication of the metamaterial l...

  9. Metal-nanocluster composites made by ion implantation: A novel third-order nonlinear material

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, R.F. Jr.; Yang, L.; Magruder, R.H. III; Becker, K.; Wittig, J.E. [Vanderbilt Univ., Nashville, TN (United States); White, C.W.; Zhur, R.A. [Oak Ridge National Lab., TN (United States); Yang, L.; Dorsinville, R.; Alfano, R.R. [City Univ. of New York, NY (United States)

    1993-03-01

    We describe our recent studies of metal-insulator nanocluster composites made by ion implantation in such substrates as glass and sapphire. The metal clusters have diameters ranging from 3 to 30 nm. The composites exhibit an electronic nonlinear optical response which is fast on the picosecond time scale. In addition to possibilities for technological application, these materials also offer a way of studying unusual properties of composite materials, such as the quantum confinement of conduction-band electrons and the transverse relaxation time T{sub 2} as a function of cluster size.

  10. Metal-nanocluster composites made by ion implantation: A novel third-order nonlinear material

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, R.F. Jr.; Yang, L.; Magruder, R.H. III; Becker, K.; Wittig, J.E. (Vanderbilt Univ., Nashville, TN (United States)); White, C.W.; Zhur, R.A. (Oak Ridge National Lab., TN (United States)); Yang, L.; Dorsinville, R.; Alfano, R.R. (City Univ. of New York, NY (United States))

    1993-03-01

    We describe our recent studies of metal-insulator nanocluster composites made by ion implantation in such substrates as glass and sapphire. The metal clusters have diameters ranging from 3 to 30 nm. The composites exhibit an electronic nonlinear optical response which is fast on the picosecond time scale. In addition to possibilities for technological application, these materials also offer a way of studying unusual properties of composite materials, such as the quantum confinement of conduction-band electrons and the transverse relaxation time T[sub 2] as a function of cluster size.

  11. Superelement methods applications to micromechanics of high temperature metal matrix composites

    Science.gov (United States)

    Caruso, J. J.; Chamis, C. C.

    1988-01-01

    Adaptation of the superelement finite-element method for micromechanics of continuous fiber high temperature metal matrix composites (HT-MMC) is described. The method is used to predict the thermomechanical behavior of P100-graphite/copper composites using MSC/NASTRAN and it is also used to validate those predicted by using an in-house computer program designed to perform micromechanics for HT-MMC. Typical results presented in the paper include unidirectional composite thermal properties, mechanical properties, and microstresses.

  12. A review on conventional and laser assisted machining of Aluminium based metal matrix composites

    OpenAIRE

    2014-01-01

    Aluminum based Metal Matrix Composites (Al-MMC) have been found in different industrial applications due its excellent properties compared to conventional materials. Machining of these composites is difficult due to the hard particle reinforcements. The wider usage of these composites is limited due high machining cost and excessive tool wear with conventional machining. Because of increasing demands in industries, any improvement of conventional machining process or any other deployment of a...

  13. Wear of metal-free resin composite crowns after three years in service.

    Science.gov (United States)

    Zenthöfer, Andreas; Rammelsberg, Peter; Schmitt, Clemens; Ohlmann, Brigitte

    2013-01-01

    To compare differences between the wear behavior of two types of metal-free resin composite crown with a control after three years in clinical service. Sixty-six participants needing one to three posterior single crowns were fitted with 120 crowns. Abutment teeth were randomly assigned to three groups: 40 resin composite crowns with fiber-reinforced framework, 40 resin composite crowns without fiber-reinforced framework, and 40 metal-ceramic crowns. To assess wear, gypsum replicas of the crowns were fabricated and scanned with a 3D laser scanner at baseline and after three years. Differences between the groups were analyzed by use of mixed-effects regression models. Wear of resin composite crowns with fiber-reinforced framework (p=0.0043) and resin composite crowns without framework (p=0.0246) was significantly greater than in the metal-ceramic group. Wear of metal-free resin composite crowns after three years was significantly greater than that of metal-ceramic crowns, but the wear was still clinically acceptable.

  14. Two-Criteria Analysis of Casting Technologies of Metal and Composite Foams

    Directory of Open Access Journals (Sweden)

    Gawdzińska K.

    2015-04-01

    Full Text Available The determination of potential areas of application for metal foams allows to precisely define properties these materials are expected to have. The characteristics of metal foams are strictly related to their cellular structure, which in turn depends on the manufacturing method and materials used. Obviously, metal foam producers should strive to make these materials using inexpensive, or cost-effective technologies, yielding possibly good quality and being environment-friendly. This paper briefly characterizes the manufacturing of metal and composite foams by casting methods. We determine an optimal manufacturing method based on a matrix diagram for metal and composite foams satisfying the two - criteria: “manufacturing costs” (depending on the price of production equipment and labour, cost of materials for foam manufacturing, environmental impact and “foam quality” (depending on the manufacturing precision, homogeneity of the structure, pore size, shape, and volumetric fraction.

  15. Synthesis of branched metal nanostructures with controlled architecture and composition

    Science.gov (United States)

    Ortiz, Nancy

    On account of their small size, metal nanoparticles are proven to be outstanding catalysts for numerous chemical transformations and represent promising platforms for applications in the fields of electronics, chemical sensing, medicine, and beyond. Many properties of metal nanoparticles are size-dependent and can be further manipulated through their shape and architecture (e.g., spherical vs. branched). Achieving morphology control of nanoparticles through solution-based techniques has proven challenging due to limited knowledge of morphology development in nanosyntheses. To overcome these complications, a systematic examination of the local ligand environment of metal precursors on nanostructure formation was undertaken to evaluate its contribution to nanoparticle nucleation rate and subsequent growth processes. Specifically, this thesis will provide evidence from ex situ studies---Transmission Electron Microscopy (TEM) and UV-visible spectroscopy (UV-Vis)---that support the hypothesis that strongly coordinated ligands delay burst-like nucleation to generate spherical metal nanoparticles and ligands with intermediate binding affinity regulate the gradual reduction of metal precursors to promote aggregated assembly of nanodendrites. These ex situ studies were coupled with a new in situ perspective, providing detailed understanding of metal precursor transformation, its direct relation to nanoparticle morphology development, and the ligand influence towards the formation of structurally complex metal nanostructures, using in situ synchrotron X-ray Diffraction (XRD) and Ultra Small-Angle X-ray Scattering (USAXS). The principles extracted from the study of monometallic nanostructure formation were also found to be generally applicable to the synthesis of bimetallic nanostructures, e.g., Pd-Pt architectures, with either core-shell or alloyed structures that were readily achieved by ligand selection. These outcomes provide a direct connection between fundamental

  16. Nanotubular J-aggregates covered by transparent silica nanoshells

    CERN Document Server

    Qiao, Yan; Kirmse, Holm; Kirstein, Stefan; Rabe, Jürgen P

    2015-01-01

    Nanotubular J-aggregates of amphiphilic cyanine dyes exhibit highly attractive opto-electronic properties, reminiscent to natural light harvesting complexes. However, their photo-chemical and mechanical stabilities are limited. A robust transparent shell covering the J aggregates may alleviate these issues. Here, organic-inorganic hybrid nanotubes have been synthesized based on in-situ coating the nanotubular J-aggregates with silica through the sol-gel method. The growth of the shell is controlled by electrostatic adsorption of the silica precursors. The resulting silica nanoshells exhibit a regular superstructure that consists of ribbons that helically wind around the tubular aggregates. The molecular structure of the aggregates and hence their spectral properties remain unaffected by the silication process. The overall shell thickness can be controlled by the ratio and the absolute concentration of the precursors. The usage of a precursor containing diamine groups leads to the formation of bundles of the t...

  17. Dispersion and infrared jamming performance of hollow nanoshell smoke

    Science.gov (United States)

    Zhang, T.; Dai, X. D.; Ren, L. N.; Chen, L.; Dai, M. Y.; Liu, X. C.; Jiang, Y.; Chen, C. S.; Liu, H. F.

    2013-09-01

    A new hollow nanoshell semiconductor was applied for generating smoke screen, and the dispersion and infrared jamming performance were researched. Firstly, the mircostructures and dispersion performance of the screen particles were analized by using SEM and cascade impactor; basing on the findings, the jamming performance of the screen to 8-12μm infrared light, 1.06 μm laser and 10.6 μm laser were examined, and the primary affecting factors and relationships got concluded. The results show that the dispersion performance is favorable as the diameters of more than 70% smoke particles are below 6.1μm the smoke screen has better and satisfactory jamming performance to IR and laser as within 10 min, the decay rate maintains above 85% to 8-12μm IR and 90% to 1.06μm laser and10.6μm laser.

  18. Jointly Tuned Plasmonic–Excitonic Photovoltaics Using Nanoshells

    KAUST Repository

    Paz-Soldan, Daniel

    2013-04-10

    Recent advances in spectrally tuned, solution-processed plasmonic nanoparticles have provided unprecedented control over light\\'s propagation and absorption via engineering at the nanoscale. Simultaneous parallel progress in colloidal quantum dot photovoltaics offers the potential for low-cost, large-area solar power; however, these devices suffer from poor quantum efficiency in the more weakly absorbed infrared portion of the sun\\'s spectrum. Here, we report a plasmonic-excitonic solar cell that combines two classes of solution-processed infrared materials that we tune jointly. We show through experiment and theory that a plasmonic-excitonic design using gold nanoshells with optimized single particle scattering-to-absorption cross-section ratios leads to a strong enhancement in near-field absorption and a resultant 35% enhancement in photocurrent in the performance-limiting near-infrared spectral region. © 2013 American Chemical Society.

  19. Additive Manufacturing and Characterization of Polylactic Acid (PLA) Composites Containing Metal Reinforcements

    Science.gov (United States)

    Kuentz, Lily; Salem, Anton; Singh, M.; Halbig, M. C.; Salem, J. A.

    2016-01-01

    Additive manufacturing of polymeric systems using 3D printing has become quite popular recently due to rapid growth and availability of low cost and open source 3D printers. Two widely used 3D printing filaments are based on polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) systems. PLA is much more environmentally friendly in comparison to ABS since it is made from renewable resources such as corn, sugarcane, and other starches as precursors. Recently, polylactic acid-based metal powder containing composite filaments have emerged which could be utilized for multifunctional applications. The composite filaments have higher density than pure PLA, and the majority of the materials volume is made up of polylactic acid. In order to utilize functionalities of composite filaments, printing behavior and properties of 3-D printed composites need to be characterized and compared with the pure PLA materials. In this study, pure PLA and composite specimens with different metallic reinforcements (Copper, Bronze, Tungsten, Iron, etc) were 3D printed at various layer heights and resulting microstructures and properties were characterized. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) behavior of filaments with different reinforcements were studied. The microscopy results show an increase in porosity between 3-D printed regular PLA and the metal composite PLA samples, which could produce weaker mechanical properties in the metal composite materials. Tensile strength and fracture toughness behavior of specimens as a function of print layer height will be presented.

  20. Compositional landscape for glass formation in metal alloys.

    Science.gov (United States)

    Na, Jong Hyun; Demetriou, Marios D; Floyd, Michael; Hoff, Andrew; Garrett, Glenn R; Johnson, William L

    2014-06-24

    A high-resolution compositional map of glass-forming ability (GFA) in the Ni-Cr-Nb-P-B system is experimentally determined along various compositional planes. GFA is shown to be a piecewise continuous function formed by intersecting compositional subsurfaces, each associated with a nucleation pathway for a specific crystalline phase. Within each subsurface, GFA varies exponentially with composition, wheres exponential cusps in GFA are observed when crossing from one crystallization pathway to another. The overall GFA is shown to peak at multiple exponential hypercusps that are interconnected by ridges. At these compositions, quenching from the high-temperature melt yields glassy rods with diameters exceeding 1 cm, whereas for compositions far from these cusps the critical rod diameter drops precipitously and levels off to 1 to 2 mm. The compositional landscape of GFA is shown to arise primarily from an interplay between the thermodynamics and kinetics of crystal nucleation, or more precisely, from a competition between driving force for crystallization and liquid fragility.

  1. Albumin nanoshell encapsulation of near-infrared-excitable rare-Earth nanoparticles enhances biocompatibility and enables targeted cell imaging.

    Science.gov (United States)

    Naczynski, Dominik J; Andelman, Tamar; Pal, David; Chen, Suzie; Riman, Richard E; Roth, Charles M; Moghe, Prabhas V

    2010-08-02

    The use of traditional fluorophores for in vivo imaging applications is limited by poor quantum yield, poor tissue penetration of the excitation light, and excessive tissue autofluorescence, while the use of inorganic fluorescent particles that offer a high quantum yield is frequently limited due to particle toxicity. Rare-earth-doped nanoparticles that utilize near-infrared upconversion overcome the optical limitations of traditional fluorophores, but are not typically suitable for biological application due to their insolubility in aqueous solution, lack of functional surface groups for conjugation of biomolecules, and potential cytotoxicity. A new approach to establish highly biocompatible and biologically targetable nanoshell complexes of luminescent rare-earth-doped NaYF(4) nanoparticles (REs) excitable with 920-980 nm near-infrared light for biomedical imaging applications is reported. The approach involves the encapsulation of NaYF(4) nanoparticles doped with Yb and Er within human serum albumin nanoshells to create water-dispersible, biologically functionalizable composite particles. These particles exhibit narrow size distributions around 200 nm and are stable in aqueous solution for over 4 weeks. The albumin shell confers cytoprotection and significantly enhances the biocompatibility of REs even at concentrations above 200 microg REs mL(-1). Composite particles conjugated with cyclic arginine-glycine-aspartic acid (cRGD) specifically target both human glioblastoma cell lines and melanoma cells expressing alpha(v)beta(3) integrin receptors. These findings highlight the promise of albumin-encapsulated rare-earth nanoparticles for imaging cancer cells in vitro and the potential for targeted imaging of disease sites in vivo.

  2. Corrosion and wear resistance of titanium- and aluminum-based metal matrix composites fabricated by direct metal laser deposition

    Science.gov (United States)

    Waldera, Benjamin L.

    Titanium- and Aluminum-based metal matrix composites (MMC) have shown favorable properties for aerospace applications such as airframes, reinforcement materials and joining elements. In this research, such coatings were developed by direct metal laser deposition with a powder-fed fiber coupled diode laser. The MMC formulations consisted of pure titanium and aluminum matrices with reinforcing powder blends of chromium carbide and tungsten carbide nickel alloy. Two powder formulations were investigated for each matrix material (Ti1, Ti2, Al1 and Al2). Titanium based composites were deposited onto a Ti6Al4V plate while aluminum composites were deposited onto AA 7075 and AA 5083 for Al1 and Al2, respectively. Microstructures of the MMCs were studied by optical and scanning electron microscopy. The hardness and reduced Young's modulus (Er) were assessed through depth-sensing instrumented nanoindentation. microhardness (Vickers) was also analyzed for each composite. The corrosion resistance of the MMCs were compared by monitoring open circuit potential (OCP), polarization resistance (Rp) and potentiodynamic polarization in 0.5 M NaCl to simulate exposure to seawater. The Ti-MMCs demonstrated improvements in hardness between 205% and 350% over Ti6Al4V. Al-MMCs showed improvements between 47% and 79% over AA 7075 and AA 5083. The MMCs showed an increase in anodic current density indicating the formation of a less protective surface oxide than the base metals.

  3. Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Kim S.-Y.

    2015-06-01

    Full Text Available Porous metallic materials have been widely used in many fields including aerospace, atomic energy, electro chemistry and environmental protection. Their unique structures make them very useful as lightweight structural materials, fluid filters, porous electrodes and catalyst supports. In this study, we fabricated Ni-based porous metallic glasses having uniformly dispersed micro meter pores by the sequential processes of ball-milling and chemical dissolution method. We investigated the application of our porous metal supported for Pt catalyst. The oxidation test was performed in an atmosphere of 1% CO and 3% O2. Microstructure observation was performed by using a scanning electron microscope. Oxidation properties and BET (Brunauer, Emmett, and Teller were analyzed to understand porous structure developments. The results indicated that CO Oxidation reaction was dependent on the specific surface area.

  4. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

    Directory of Open Access Journals (Sweden)

    S. C. Nagaraju

    2014-01-01

    Full Text Available Polyaniline- (PANI praseodymium Oxide (Pr2O3 composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

  5. Friction material composites copper-metal-free material design perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2015-01-01

    This book examines material composites used in connection with brake friction, their design and safety. To aid in understanding, the essentials of friction are explained. This second edition was extended to include friction material composites without copper, as they offer an environmentally friendlier option. The second edition is intended to support beginners by offering insights into the essentials of friction material composites, helping them to develop a broader understanding of brake friction materials. Friction materials find wide-ranging applications in household and industrial appliances, brake pads for automotive applications, rail brake friction pads and composition brake blocks. This second edition is an introductory volume to a set of related books, and is based on the author’s experience and expertise with various material manufacturers, brake manufacturers, vehicle manufacturers, researchers and testing labs around the world with which the author has been associated for the past 28 years.

  6. Multifunctional Metal Matrix Composite Filament Wound Tank Liners Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Composite Overwrapped Pressure Vessels (COPVs) are used for storing pressurized gases on board spacecraft when mass saving is a key requirement. All future mass...

  7. CONSTITUTIVE RELATION OF DISCONTINUOUS REINFORCED METAL-MATRIX COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    季葆华; 王自强

    2001-01-01

    A micromechanical model is developed to simulate the mechanical behaviors of discontinuous reinforced composites. The analysis for a representative unit cell is based on the assumption of a periodic array of aligned reinforcements.The minimum energy principle is used to determine the unknown coefficients of the displacement field of the unit cell. The constitutive behavior of composites is studied to obtain the relationship between the main variables of matrix and reinforcements.It is concluded that the flow strength of composites is strongly influenced by volume fraction, aspect ratio of reinforcement, and the strain hardening exponent of matrix.An analytical constitutive relation of composites is obtained. The predicted results are in agreement with the existing experimental and numerical results.

  8. Simplified prediction model for elastic modulus of particulate reinforced metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-ming; PAN Fu-sheng; LU Yun; ZENG Su-min

    2006-01-01

    Some structural parameters of the metal matrix composite, including particulate shape and distribution do not influence the elastic modulus. A prediction model for the elastic modulus of particulate reinforced metal matrix Al composite was developed and improved. Expressions of rigidity and flexibility of the rule of mixing were proposed. A five-zone model for elasticity performance calculation of the composite was proposed. The five-zone model is thought to be able to reflect the effects of the MMC interface on elastic modulus of the composite. The model overcomes limitations of the currently-understood rigidity and flexibility of the rule of mixing. The original idea of a five-zone model is to propose particulate/interface interactive zone and matrix/interface interactive zone. By integrating organically with the law of mixing, the new model is found to be capable of predicting the engineering elastic constants of the MMC composite.

  9. Symposium Review: Metal and Polymer Matrix Composites at MS&T 2013

    Science.gov (United States)

    Gupta, Nikhil; Paramsothy, Muralidharan

    2014-06-01

    This article reflects on the presentations made during the Metal and Polymer Matrix Composites symposium at Materials Science and Technology 2013 (MS&T'13) held in Montreal (Quebec, Canada) from October 27 to 31. The symposium had three sessions on metal matrix composites and one session on polymer matrix composites containing a total of 23 presentations. While the abstracts and full-text papers are available through databases, the discussion that took place during the symposium is often not captured in writing and gets immediately lost. We have tried to recap some of the discussion in this article and hope that it will supplement the information present in the proceedings. The strong themes in the symposium were porous composites, aluminum matrix composites, and nanocomposites. The development of processing methods was also of interest to the speakers and attendees.

  10. Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

    Science.gov (United States)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1990-01-01

    A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

  11. Numerical investigation of thermal response of laser-irradiated biological tissue phantoms embedded with gold nanoshells.

    Science.gov (United States)

    Phadnis, Akshay; Kumar, Sumit; Srivastava, Atul

    2016-10-01

    The work presented in this paper focuses on numerically investigating the thermal response of gold nanoshells-embedded biological tissue phantoms with potential applications into photo-thermal therapy wherein the interest is in destroying the cancerous cells with minimum damage to the surrounding healthy cells. The tissue phantom has been irradiated with a pico-second laser. Radiative transfer equation (RTE) has been employed to model the light-tissue interaction using discrete ordinate method (DOM). For determining the temperature distribution inside the tissue phantom, the RTE has been solved in combination with a generalized non-Fourier heat conduction model namely the dual phase lag bio-heat transfer model. The numerical code comprising the coupled RTE-bio-heat transfer equation, developed as a part of the current work, has been benchmarked against the experimental as well as the numerical results available in the literature. It has been demonstrated that the temperature of the optical inhomogeneity inside the biological tissue phantom embedded with gold nanoshells is relatively higher than that of the baseline case (no nanoshells) for the same laser power and operation time. The study clearly underlines the impact of nanoshell concentration and its size on the thermal response of the biological tissue sample. The comparative study concerned with the size and concentration of nanoshells showed that 60nm nanoshells with concentration of 5×10(15)mm(-3) result into the temperature levels that are optimum for the irreversible destruction of cancer infected cells in the context of photo-thermal therapy. To the best of the knowledge of the authors, the present study is one of the first attempts to quantify the influence of gold nanoshells on the temperature distributions inside the biological tissue phantoms upon laser irradiation using the dual phase lag heat conduction model.

  12. Nanoshell-mediated photothermal therapy can enhance chemotherapy in inflammatory breast cancer cells

    Directory of Open Access Journals (Sweden)

    Fay BL

    2015-11-01

    Full Text Available Brittany L Fay, Jilian R Melamed, Emily S Day Biomedical Engineering, University of Delaware, Newark, DE, USA Abstract: Nanoshell-mediated photothermal therapy (PTT is currently being investigated as a standalone therapy for the treatment of cancer. The cellular effects of PTT include loss of membrane integrity, so we hypothesized that nanoshell-mediated PTT could potentiate the cytotoxicity of chemotherapy by improving drug accumulation in cancer cells. In this work, we validated our hypothesis using doxorubicin as a model drug and SUM149 inflammatory breast cancer cells as a model cancer subtype. In initial studies, SUM149 cells were exposed to nanoshells and near-infrared light and then stained with ethidium homodimer-1, which is excluded from cells with an intact plasma membrane. The results confirmed that nanoshell-mediated PTT could increase membrane permeability in SUM149 cells. In complementary experiments, SUM149 cells treated with nanoshells, near-infrared light, or a combination of the two to yield low-dose PTT were exposed to fluorescent rhodamine 123. Analyzing rhodamine 123 fluorescence in cells via flow cytometry confirmed that increased membrane permeability caused by PTT could enhance drug accumulation in cells. This was validated using fluorescence microscopy to assess intracellular distribution of doxorubicin. In succeeding experiments, SUM149 cells were exposed to subtherapeutic levels of doxorubicin, low-dose PTT, or a combination of the two treatments to determine whether the additional drug uptake induced by PTT is sufficient to enhance cell death. Analysis revealed minimal loss of viability relative to controls in cells exposed to subtherapeutic levels of doxorubicin, 15% loss of viability in cells exposed to low-dose PTT, and 35% loss of viability in cells exposed to combination therapy. These data indicate that nanoshell-mediated PTT is a viable strategy to potentiate the effects of chemotherapy and warrant further

  13. Nanoshells as a high-pressure gauge analyzed to 200 GPa

    Science.gov (United States)

    Van den Broeck, Nick; Putteneers, Katrijn; Tempere, Jacques; Silvera, Isaac F.

    2011-12-01

    In this article, we present calculations that indicate that nanoshells can be used as a high-pressure gauge in diamond anvil cells (DACs). Nanoparticles have important advantages in comparison with the currently used ruby fluorescence gauge. Because of their small dimensions, they can be spread uniformly over a diamond surface without bridging between the two diamond anvils. Furthermore, their properties are measured by broad-band optical transmission spectroscopy leading to a very large signal-to-noise ratio even in the multi-megabar pressure regime where ruby measurements become challenging. Finally, their resonant frequencies can be tuned to lie in a convenient part of the visible spectrum accessible to CCD detectors. Theoretical calculations for a nanoshell with a SiO2 core and a golden shell, using both the hybridization model and Mie theory, are presented here. The calculations for the nanoshell in vacuum predict that nanoshells can indeed have a measurable pressure-dependent optical response desirable for gauges. However, when the nanoshells are placed in commonly used DAC pressure media, resonance peak positions as a function of pressure are no longer single valued and depend on the pressure media, rendering them impractical as a pressure gauge. To overcome these problems, an alternative nanoparticle is studied: coating the nanoshell with an extra dielectric layer (SiO2) provides an easy way to shield the pressure gauge from the influence of the medium, leaving the compression of the particle as a result of the pressure as the main effect on the spectrum. We have analyzed the response to pressure up to 200 GPa. We conclude that a coated nanoshell could provide a new gauge for high-pressure measurements that has advantages over current methods.

  14. Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The current development in the intramolecular aromatic-ring stacking i nteractions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions i n several important systems about ternary mixed-ligand complexes, including nucl eotide-metal ion-po- lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleotide-metal ion-amino ac id, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interacti ons in the complexes. Based on the study of stacking interaction in the complexe s, the mechanism of interaction between DNA molecules and complexes of heteroaro matic N-bases has been established, which is crucial for the design and synthesi s of the complexes acting as molecular devices of DNA.

  15. Process of forming a sol-gel/metal hydride composite

    Science.gov (United States)

    Congdon, James W.

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  16. Heavy metal analyses and nutritional composition of raw and ...

    African Journals Online (AJOL)

    ... trend moisture (43.24 - 76.79 %) > carbohydrate (3.16 – 63.45 %) > protein ... In this study, these fishes are generally low in fats (lean fish), and fish ... lower than the maximum standard level reported to be 0.5 mg/kg dry weight ... The fresh water fishes showed higher concentration of heavy metals than ... Metrics Loading .

  17. An In vitro Evaluation of Flexural Bond Strength of Indirect Composites Fused to Metal.

    Science.gov (United States)

    Sunitha, N; Ariga, Padma; Jain, Ashish R; Philip, Jacob Mathew

    2013-06-01

    With the advent of newer indirect composite resin materials for crown and bridge prosthesis, it has become imperative to evaluate their strength to serve as long term replacements as a substitute to metal ceramic restorations. This study aimed to evaluate and compare the flexural bond strength of three composite resin veneering material to metal, cured by different methods. Specimen were fabricated with pattern resin by duplicating it with machined metal die and divided into three groups. Three composite resin materials were used in this study. Group (A) received Adoro, Group (B) received Targis and Group (C) received Tescera. The bond strength of all specimens was tested with Lloyd's universal testing machine under three point loading. The highest values for fracture resistance were displayed by light, heat and pressure cured composites followed by composites cured using a temperature of 104 °C and composites with curing temperature of 95 °C. The results indicate that there is a significant difference between the three groups, with the Tescera group specimens exhibiting the highest flexural bond strength. Of the other two groups, Adoro group exhibited higher flexural bond strength than Targis group. The results of this study suggest that Tescera group with curing temperature of 130 °C and pressure of 80 Psi, cured with metal halide unit exhibited the highest flexural bond strength when compared to Adoro and Targis groups.

  18. Microstructure and Mechanical Properties of Mg-5Nb Metal-Metal Composite Reinforced with Nano SiC Ceramic Particles

    Directory of Open Access Journals (Sweden)

    Manoj Gupta

    2012-06-01

    Full Text Available In this work, a Mg-5Nb metal–metal composite was reinforced with nano SiC (SiCn ceramic reinforcement of varying volume fractions, using the disintegrated melt deposition technique. The extruded Mg-5Nb-SiCn composites were characterized for their microstructure and mechanical properties. Based on the results obtained, it was observed that the volume fraction of nano-SiC reinforcement played an important role in determining the grain size and improving the mechanical properties. A comparison of properties with those of pure Mg and Mg-5Nb composite showed that while the improvement in hardness occurred at all volume fractions, a minimum volume fraction of ~0.27% SiCn was required to increase the tensile and compressive strengths. The observed mechanical response of the composites were investigated in terms of the effect of SiCn volume fraction, processing, distribution of metallic and ceramic reinforcements and the inherent properties of the matrix and reinforcements. The influences of these factors on the mechanical behavior of the composites are understood based on the structure–property relationship.

  19. PREDICTION OF MECHANICAL PROPERTY OF WHISKER REINFORCED METAL MATRIX COMPOSITE: PART-Ⅰ. MODEL AND FORMULATION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on study of strain distribution in whisker reinforced metal matrix composites, an explicit precise stiffness tensor is derived. In the present theory, the effect of whisker orientation on the macro property of composites is considered, but the effect of random whisker position and the complicated strain field at whisker ends are averaged. The derived formula is able to predict the stiffness modulus of composites with arbitrary whisker orientation under any loading condition. Compared with the models of micro-mechanics, the present theory is competent for modulus prediction of actual engineering composites. The verification and application of the present theory are given in a subsequent paper published in the same issue.

  20. Structure-performance maps of polymeric, metal, and ceramic matrix composites

    Science.gov (United States)

    Chou, Tsu-Wei; Yang, Jenn-Ming

    1986-09-01

    This paper presents the results of extensive analytical studies of the thermo-elastic properties of unidirectional laminated composites, as well as two-dimensional and three-dimensional textile structural composites with polymeric, metal, and ceramic matrices. Some comparisons of the theoretical predictions with experimental data have been made. By the construction of the structure-performance maps, the effective composite properties based upon various reinforcement forms and fiber and matrix combinations can be easily assessed. The uniqueness of various textile structural reinforcements also has been demonstrated. These comprehensive performance maps can provide the data base necessary for material selections and guidance for future investigations of advanced composites.

  1. MCrA1Y/TaC Metal Matrix Composite Coatings Produced by Electrospark Deposition

    Institute of Scientific and Technical Information of China (English)

    Yujiang XIE; Yanhong YANG; Mingsheng WANG; Jian HOU

    2013-01-01

    MCrAlY/TaC metal matrix composite coatings with 10,20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD).The effects of TaC content on microstructure,hardness and oxidation behavior of the composite coatings were studied.The results showed that the composite coatings were composed of superfine γ columnar dendrite and large TaC particles dispersedly distributed.The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.

  2. Microbial community composition and functions are resilient to metal pollution along two forest soil gradients.

    Science.gov (United States)

    Azarbad, Hamed; Niklińska, Maria; Laskowski, Ryszard; van Straalen, Nico M; van Gestel, Cornelis A M; Zhou, Jizhong; He, Zhili; Wen, Chongqing; Röling, Wilfred F M

    2015-01-01

    Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long-term metal pollution. Studying 12 sites located along two distinct gradients of metal pollution in Southern Poland revealed that functional potential and diversity (assessed using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level did, however, significantly impact bacterial community structure (as shown by MiSeq Illumina sequencing of 16S rRNA genes), but not bacterial taxon richness and community composition. Metal pollution caused changes in the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal-resistance genes showed significant correlations with metal concentrations in soil. Our study showed that microbial communities are resilient to metal pollution; despite differences in community structure, no clear impact of metal pollution levels on overall functional diversity was observed. While screens of phylogenetic marker genes, such as 16S rRNA genes, provide only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appears to be a more promising strategy. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Escribano, J. A.; Ferrari, B.; Alvaredo, P.; Gordo, E.; Sanchez-Herencia, A. J.

    2013-07-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  4. SEISMIC Analysis of high-rise buildings with composite metal damper

    Directory of Open Access Journals (Sweden)

    Chen Ruixue

    2015-01-01

    Full Text Available This paper mainly studies on the mechanical characteristics and application effect of composite metal damper in the high-rise buildings via the numerical simulation analysis. The research adopts the elastic and elastic-plastic dynamic approach and the displacement time history response and damper energy dissipation capacity and so on of the high-rise building are compared and analyzed before and after installation. The analysis found that the energy dissipation characteristic of metallic dampers is good. High-rise building story drift significantly is reduced and the extent of damage of the walls and coupling beams is decreased, achieved a good energy dissipation effect. Composite metal damper can effectively and economically improve the seismic performance of high-rise buildings, meet the requirement of the 3-level design for seismic resistance. The result has certain reference significance for the application of metallic damper in the high-rise buildings.

  5. Two optical bistability domains in composites of metal nanoparticles with nonlinear dielectric core

    Energy Technology Data Exchange (ETDEWEB)

    Shewamare, Sisay, E-mail: sisayshewa20@yahoo.com [Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia); Mal' nev, V.N., E-mail: vadimnmalnev@yahoo.com [Department of Physics, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia)

    2012-12-15

    It is shown that the local field in metal spherical particles with a dielectric core in an external varying electric field has two maxima at two different frequencies. The second maximum becomes more important with an increment in the metal fraction. Due to the nonlinear dielectric function of the core, the composite of these inclusions may have two optically induced bistability domains at different frequencies. At rather high metal fraction, two bistability domains merge and form one entire bistability domain. The parameters of these domains are studied numerically. The paper focuses on the second bistability domain, which has not been discussed in the literature so far. This domain exists in a comparatively narrow frequency range and its onset fields are lower than those of the first bistability domain. The lowest bistability onset fields are obtained in the entire domain. This peculiarity of the optical induced bistability in the metal composite with small dielectric cores can be attractive for possible applications.

  6. Chemically stable ceramic-metal composite membrane for hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fanglin; Fang, Shumin; Brinkman, Kyle S.

    2017-06-27

    A hydrogen permeation membrane is provided that can include a metal and a ceramic material mixed together. The metal can be Ni, Zr, Nb, Ta, Y, Pd, Fe, Cr, Co, V, or combinations thereof, and the ceramic material can have the formula: BaZr.sub.1-x-yY.sub.xT.sub.yO.sub.3-.delta. where 0.ltoreq.x.ltoreq.0.5, 0.ltoreq.y.ltoreq.0.5, (x+y)>0; 0.ltoreq..delta..ltoreq.0.5, and T is Sc, Ti, Nb, Ta, Mo, Mn, Fe, Co, Ni, Cu, Zn, Ga, In, Sn, or combinations thereof. A method of forming such a membrane is also provided. A method is also provided for extracting hydrogen from a feed stream.

  7. Magnetic Response of Metal-Dielectric Composite at Short Wavelength

    CERN Document Server

    Tang, Jianwei

    2010-01-01

    We propose a new type of split-ring resonator, of which the ring is made of high index dielectric material (e.g. SiC), while metal fills the gap. Such a new magnetic metamaterial is able to operate at short wavelength including the green, blue, violet range and part of ultraviolet range. For ease of fabrication, we also proposed a new type of cut-wire pair structure based on our new type of split-ring resonator.

  8. Potential of Metal-Matrix Composites as Superalloy Substitutes

    Science.gov (United States)

    1984-04-01

    Engine Construction. Towards a Cycle without Loss: Cobalt in the Aircraft Industry. Gas Turbine Engine Design Considerations as Related to Alloys of...Developments to Reduce Strategic Materials Usage. Practical Implications of the Use of Alumlnlde Coatings for the Corrosion Protection of Superalloys in Gas ...Aaroapatlalas (ONERA) BP72, 92)22 Chatlllon, Cadax, Franca ABSTRACT ’The potential of metal-matrlx coaposltas aa qaa- turbina blada material« has

  9. Plasmonic Coupling on Dielectric Nanowire Core-Metal Sheath Composites

    Science.gov (United States)

    2010-01-01

    is still a serious issue. Here, an approach based on a redox chemical reaction of silver plating is explored, which could potentially solve the...problems related to incomplete metal coverage of the nanowires. It is known that the Tollens reaction is a silvering process often used to qualitatively...the extra Sn2 + ions were removed by a deionized water rinse, keeping the surface wet. Thus, Sn2 + ions were absorbed on the surface of the ZnO NWs via

  10. Production of Decorative Cast Metal Matrix Composites with a Complex Relief and Nonmetal Reinforcement Phase

    Directory of Open Access Journals (Sweden)

    Daniela Spasova

    2016-02-01

    Full Text Available The present paper is relevant to the research of possibilities for the production of decorative complex relief metal matrix composites (MMCs of the “invitro” type, with unformed and unchanging reinforcement (strengthening phase in the process of creating a composite. The research on the methods of metal matrix composites development in this paper has been brought to the application of different space vacuum schemes for composite synthesisof vacuuming the space for composites synthesis by using the notion of the “capillary forming”. In this method the metal matrix (copper alloy melt was infiltrated in the space between the pellets of reinforcement phase (quartz particles – SiO2, whereas the classical method adopted for the obtaining MMCs “in vitro”, uses a mechanism of forced insertion of the reinforcement phase into the ready for use melt, followed by homogenization of the composite structure. In the particular case, because the obtained composite will have a complex relief three-dimensional surface, the conditions for compacting the building phases in the three directions x, y, z should be virtually equalized. In order to accomplish the task set, a laboratory system is developed. The experiments were conducted with laboratory equipment elaborated on the base of another equipment for "capillary forming" with extra vacuum. The structures of the obtained MMCs were tested by metallographic analysis.

  11. Parametric Sizing of Composite Metal Lined Tanks for Bimodal Nuclear Thermal Propulsion Applications

    Science.gov (United States)

    Abumeri, Galib H.; Roche, Joseph M.

    2006-01-01

    A computational method is described to evaluate the structural performance of composite over-wrapped metal lined LH2 tanks. This work was performed in support of the human space exploration initiative undertaken by NASA. The method is a judicious combination of available computer codes for finite elements, composite mechanics, durability, damage tracking, and damage tolerance. To illustrate the effectiveness of the analytical approach, composite over-wrapped LH2 core tanks of the Bimodal Nuclear Thermal Rocket (BNTR) were sized parametrically using launch loads and burst test requirements. The benefits and debits of inserting advanced composite technology into existing LH2 tank design concepts are evaluated in the paper. Results obtained indicate that LH2 tanks made from tape placement carbon fiber in a toughened epoxy matrix backed by a metallic liner for hermiticity are able to: (1) sustain micro-cracking in the matrix of the composite system prior to liner failure, (2) offer significant weight savings as compared to present technology (up to 31%), and (3) use unified design and weight configuration to support both launch loads and burst test requirements. The structural performance and sizing evaluation was performed for composite tanks varying in length from 10 m to 28 m. Weight calculations for the composite over-wrapped tanks show that the larger the tank length, the larger the weight savings (compared to those of traditional metallic tanks).

  12. Effects of Metallicity on the Chemical Composition of Carbon Stars

    CERN Document Server

    Leisenring, J M; Sloan, G C

    2008-01-01

    We present \\emph{Spitzer} IRS data on 19 asymptotic giant branch (AGB) stars in the Large Magellanic Cloud, complementing existing published data sets of carbon stars in both Magellanic Clouds and the Milky Way, to investigate the effects of metallicity on dust and molecular spectral features arising from the circumstellar envelope. We find that the C$_2$H$_2$ P and R branches at 7.5 micron are affected by dust dilution at higher mass-loss rates -- albeit to a lesser extent for sources in the Magellanic Clouds, compared to the Milky Way -- while the narrow 13.7 micron C$_2$H$_2$ Q branch only shows the effect of dust dilution at low mass-loss rates. A strong metallicity dependence is not observed for the Q branch. Independent of metallicity, we also provide an explanation for the observed shifts in the central wavelength of the SiC emission feature, as we show that these are largely caused by molecular band absorption on either side of the dust emission feature, dominating over shifts in the central wavelengt...

  13. Kinetics of transformation in an in-situ aluminum-strontium deformation processed metal-metal composite

    Science.gov (United States)

    Frerichs, Andrew Elliott

    2011-12-01

    Efficient electricity transmission is a key component in all plans to increase the amount of renewable power used in the decades ahead. Prime solar and wind generation sites are usually distant from major population centers, resulting in the need for improved conductor wires that are stronger, lighter, and have better conductivity than conventional conductors. Deformation processed metal-metal composites (DMMCs) have a desirable combination of high strength and good conductivity. One such DMMC, aluminum-strontium, was investigated in this study. The composite wire was created by extrusion, swaging, and wire drawing of bundled Al and Sr wires. Intermetallic compound formation between Al and Sr is of particular interest to produce a strong, conductive wire with good high-temperature strength. Samples of swaged and drawn Al-Sr composite wire were heat treated at 483K, 513K, 543K and 573K to produce samples at varying stages of intermetallic compound formation. Resistivity measurements were taken from samples over a range of heat treatment times and temperatures to calculate the activation energy for Al-Sr intermetallic compound formation. Scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction were used to investigate the changes in the microstructure occurring in the samples as a function of heat treatment. In addition, mechanical properties data were generated for pure Sr metal.

  14. An Experimental Study of Fiberglass Composites Containing Metal Wire Joints

    Science.gov (United States)

    2009-09-01

    VARTM) technique for fabricating composite materials was provided by Naval Surface Warfare Center Carderock Division (NSWCCD). The VARTM apparatus...testing. Mode I testing consisted of a double cantilever beam (DCB) test, as shown in Figure [26]. Piano hinges, used to apply the load, were attached

  15. Influence of metal loading on hydrocracking of rapeseed oil using bifunctional micro-/mesoporous composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Gille, T.; Busse, O.; Reschetilowski, W. [Technische Univ. Dresden (Germany). Inst. of Industrial Chemistry

    2013-11-01

    Hydrocracking of rapeseed oil has been investigated in a fixed bed reactor under integral conditions. A synthesized micro-/mesoporous composite material Al-MCM-41/ZSM-5 modified by different metal loadings (NiMo, PtNiMo, Pt) was used as catalyst system. It could be demonstrated that the support material and their metal loading influence the product selectivity as well as the deactivation tendencies of the catalyst sample. (orig.)

  16. Evaluation of shear bond strength of composite resin to nonprecious metal alloys with different surface treatments

    OpenAIRE

    Yassini E.; Almasi S

    2007-01-01

    Background and Aim: Replacing fractured ceramometal restorations may be the best treatment option, but it is costly. Many different bonding systems are currently available to repair the fractured ceramometal restorations. This study compared the shear bond strength of composite to a base metal alloy using 4 bonding systems.Materials and Methods: In this experimental in vitro study, fifty discs, casted in a Ni-Cr-Be base metal alloy (Silvercast, Fulldent),were ground with 120, 400 and 600 grit...

  17. Manipulated localized surface plasmon resonances in silver nanoshells coated with a spherical anisotropic layer

    Institute of Scientific and Technical Information of China (English)

    Jiang Shu-Min; Wu Da-Jian; Cheng Ying; Liu Xiao-Jun

    2012-01-01

    The influences of the anisotropy of the outer spherically anisotropic (SA) layer on the far-field spectra and near-field enhancements of the silver nanoshells are investigated by using a modified Mie scattering theory.It is found that with the increase of the anisotropic value of the SA layer,the dipole resonance wavelength of the silver nanoshell first increases and then decreases,while the local field factor (LFF) reduces.With the decrease of SA layer thickness,the dipole wavelength of the silver nanoshell shows a distinct blue-shift.When the SA layer becomes very thin,the modulations of the anisotropy of the SA layer on the plasmon resonance energy and the near-field enhancement are weakened.We further find that the smaller anisotropic value of the SA layer is helpful for obtaining the larger near-field enhancement in the Ag nanoshell.The geometric average of the dielectric components of the SA layer has a stronger effect on the plasmon resonance energy of the silver nanoshell than on the near-field enhancement.

  18. Simulation and experimental results of optical and thermal modeling of gold nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Ghazanfari, Lida; Khosroshahi, Mohammad E., E-mail: khosrom@mie.utoronto.ca

    2014-09-01

    This paper proposes a generalized method for optical and thermal modeling of synthesized magneto-optical nanoshells (MNSs) for biomedical applications. Superparamagnetic magnetite nanoparticles with diameter of 9.5 ± 1.4 nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8 ± 3.5 nm MNSs. In this paper, simulations and detailed analysis are carried out for different nanoshell geometry to achieve a maximum heat power. Structural, magnetic and optical properties of MNSs are assessed using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), UV–VIS spectrophotometer, dynamic light scattering (DLS), and transmission electron microscope (TEM). Magnetic saturation of synthesized magnetite nanoparticles are reduced from 46.94 to 11.98 emu/g after coating with gold. The performance of the proposed optical–thermal modeling technique is verified by simulation and experimental results. - Highlights: • Proposing a generalized method for optical and thermal modeling of nanoshells • Verification of the proposed modeling technique by simulation and experimental results • Simulations for different nanoshell geometry to achieve a maximum heat power • Synthesis and characterization of magneto-optical nanoshells.

  19. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, Joseph C.; Wong, Frank M. G.; Haslam, Jeffery J.; Ji, Xiaoyan (Jane); Day, Sumner D.; Blue, Craig A.; Rivard, John D. K.; Aprigliano, Louis F.; Kohler, Leslie K.; Bayles, Robert; Lemieux, Edward J.; Yang, Nancy; Perepezko, John H.; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J.

    2013-07-09

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  20. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, Joseph C; Wong, Frank M.G.; Haslam, Jeffery J; Ji, Xiaoyan; Day, Sumner D; Blue, Craig A; Rivard, John D.K.; Aprigliano, Louis F; Kohler, Leslie K; Bayles, Robert; Lemieux, Edward J; Yang, Nancy; Perepezko, John H; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J

    2013-09-03

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  1. Combined-load buckling behavior of metal-matrix composite sandwich panels under different thermal environments

    Science.gov (United States)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

    Combined compressive and shear buckling analysis was conducted on flat rectangular sandwich panels with the consideration of transverse shear effects of the core. The sandwich panel is fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that the square panel has the highest combined load buckling strength, and that the buckling strength decreases sharply with the increases of both temperature and panel aspect ratio. The effect of layup (fiber orientation) on the buckling strength of the panels was studied in detail. The metal matrix composite sandwich panel was much more efficient than the sandwich panel with nonreinforced face sheets and had the same specific weight.

  2. Characterizations of Enriched Metallic Single-Walled Carbon Nanotubes in Polymer Composite

    Science.gov (United States)

    Chen, Bin; Li, Jing; Lu, Yijiang; Cinke, Martin; Au, Dyng; Harmon, Julie P.; Muisener, Patricia Anne O.; Clayton, LaNetra; D'Angelo, John

    2003-01-01

    Using different processing conditions, we disperse the single-walled carbon nanotube (SWNT) into the polymethyl methacrylate (PMMA) to form composites. In the melt-blended sample, the SWNTs originally semiconducting - became predominantly metallic after dispersion into the melt-blended composite. The interaction of the PMMA and SWNT is investigated by the polarized Raman studies. The structure changes in the PMMA and SWNT shows that the anisotropic interactions are responsible for SWNT electronic density of states (DOS) changes. The increased metallic SWNT percentage is confirmed by the conductivity and dielectric constant measurements .

  3. Processing and Electromagnetic Shielding Properties of Multifunctional Metal Composite Knitted Fabric used as Socks

    OpenAIRE

    Yu Zhicai; He Hualing; Han Yutong; Lin Fei; Yang Xiaori; Zhu Shun; Wang Nan; Lin Jia-Horng

    2016-01-01

    In this research, a type of bamboo charcoal polyester (BC-PET)/antibacterial nylon(AN)/stainless steel wire (SSW) metal composite yarn was prepared with a hollow spindle spinning machine, which using the SSW as the core material, the BC-PET and AN as the outer and inner wrapped yarns, respectively. The wrapping numbers was set at 8.0turns/cm for the produced metal composite yarns. Furthermore, a type of plated knitted fabric was designed and produced by using the automatic jacquard knitting m...

  4. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation.

    Science.gov (United States)

    Mazhorova, Anna; Gu, Jian Feng; Dupuis, Alexandre; Peccianti, Marco; Tsuneyuki, Ozaki; Morandotti, Roberto; Minamide, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-11-22

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. Finally, we study challenges in the fabrication of metamaterials with sub-micrometer metallic wires by repeated stack-and-draw process by comparing samples made using 2, 3 and 4 consecutive drawings. When using metallic alloys we observe phase separation effects and nano-grids formation on small metallic wires.

  5. Wear Behavior of Mechanically Alloyed Ti-Based Bulk Metallic Glass Composites Containing Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    2016-11-01

    Full Text Available The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT particles. Changes in glass transition temperature (Tg and crystallization temperature (Tx suggest that deviations in the chemical composition of the amorphous matrix occurred because of a partial dissolution of the CNT species into the amorphous phase. Although the hardness of CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composites is increased with the addition of CNT particles, the wear resistance of such composites is not directly proportional to their hardness, and does not follow the standard wear law. A worn surface under a high applied load shows that the 12 vol. % CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composite suffers severe wear compared with monolithic Ti50Cu28Ni15Sn7 bulk metallic glass.

  6. Evaluation of hydrogenation properties on MgHx-transition metal fluoride composites by planetary ball milling

    Science.gov (United States)

    Jang, Min-Hyuk; Park, So-Hyun; Kim, Whan-Gi; Hong, Tae-Whan

    2015-11-01

    To improve the disadvantages of Mg hydrides, a few studies were conducted for MgHx intermixed with transition metal fluorides. MgF2 formed from the MgHx-transition metal fluoride system can be replaces the initial surface oxide layer and provides a reactive and protective fluorinated surface for for hydrogen uptake. Thus, the absorption/desorption kinetics will be enhanced. In this research, MgHx-transition metal fluoride composites mixture has been prepared by hydrogen induced planetary ball milling. The synthesized powders were characterized by X-ray diffraction analysis, scanning electron microscopy and simultaneous thermogravimetric, differential scanning calorimetric analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic pressure-composition-temperature apparatus without any activation treatment. From the characteristics of the absorption kinetics and curves observed, the role of transition metal fluoride was catalyst in hydrogen absorption. The results of Pressure-Composition Isotherm curve, available hydrogen storage amount for MgHx-5 vol% CoF2 composites were 4.85 wt%, for MgHx-5 vol%TiF3 composites were 4.88 wt%. at 623K in the 5th cycle.

  7. Plasmonically Enhanced Photocatalytic Hydrogen Production from Water: The Critical Role of Tunable Surface Plasmon Resonance from Gold-Silver Nanoshells.

    Science.gov (United States)

    Li, Chien-Hung; Li, Min-Chih; Liu, Si-Ping; Jamison, Andrew C; Lee, Dahye; Lee, T Randall; Lee, Tai-Chou

    2016-04-13

    Gold-silver nanoshells (GS-NSs) having a tunable surface plasmon resonance (SPR) were employed to facilitate charge separation of photoexcited carriers in the photocalytic production of hydrogen from water. Zinc indium sulfide (ZnIn2S4; ZIS), a visible-light-active photocatalyst, where the band gap varies with the [Zn]/[In] ratio, was used as a model ZIS system (E(g) = 2.25 eV) to investigate the mechanisms of plasmonic enhancement associated with the nanoshells. Three types of GS-NS cores with intense absorptions centered roughly at 500, 700, and 900 nm were used as seeds for preparing GS-NS@ZIS core-shell structures via a microwave-assisted hydrothermal reaction, yielding core-shell particles with composite diameters of ∼200 nm. Notably, an interlayer of dielectric silica (SiO2) between the GS-NSs and the ZIS photocatalyst provided another parameter to enhance the production of hydrogen and to distinguish the charge-transfer mechanisms. In particular, the direct transfer of hot electrons from the GS-NSs to the ZIS photocatalyst was blocked by this layer. Of the 10 particle samples examined in this study, the greatest hydrogen gas evolution rate was observed for GS-NSs having a SiO2 interlayer thickness of ∼17 nm and an SPR absorption centered at ∼700 nm, yielding a rate 2.6 times higher than that of the ZIS without GS-NSs. The apparent quantum efficiencies for these core-shell particles were recorded and compared to the absorption spectra. Analyses of the charge-transfer mechanisms were evaluated and are discussed based on the experimental findings.

  8. Polymer, metal, and ceramic matrix composites for advanced aircraft engine applications

    Science.gov (United States)

    Mcdanels, D. L.; Serafini, T. T.; Dicarlo, J. A.

    1986-01-01

    Advanced aircraft engine research within NASA Lewis is being focused on propulsion systems for subsonic, supersonic, and hypersonic aircraft. Each of these flight regimes requires different types of engines, but all require advanced materials to meet their goals of performance, thrust-to-weight ratio, and fuel efficiency. The high strength/weight and stiffness/weight properties of resin, metal, and ceramic matrix composites will play an increasingly key role in meeting these performance requirements. At NASA Lewis, research is ongoing to apply graphite/polyimide composites to engine components and to develop polymer matrices with higher operating temperature capabilities. Metal matrix composites, using magnesium, aluminum, titanium, and superalloy matrices, are being developed for application to static and rotating engine components, as well as for space applications, over a broad temperature range. Ceramic matrix composites are also being examined to increase the toughness and reliability of ceramics for application to high-temperature engine structures and components.

  9. Research of structure, mechanical and operation properties of glass-metal composites

    Science.gov (United States)

    Lyubimova, O. N.; Lyubimov, E. V.; Solonenko, E. P.; Morkovin, A. V.; Dryuk, S. A.

    2016-11-01

    The technological bases for the creation of the new structural material—glass-metal composite—are explored in this paper. Properties of the new material: structure and properties of the contact zone of glass and steel, tensile strength under static and dynamic loading, corrosion resistance and abrasion resistance under abrasive wear in the corrosive environment are theoretically and experimentally studied. The limit of thermal stability for experimental composite specimens equals 440°C. Corrosion tests show that the corrosion acceleration is the same for all composite specimens and does not depend on the solution concentration and the initial specimen weight. Steel specimens show significant changes in geometrical characteristics in comparison with composite specimens. Its prospect and ability to compete with steel is proved. The practical application is proposed for glass-metal composite rods.

  10. Temperature-dependent Goos-Hänchen shift on the interface of metal/dielectric composites.

    Science.gov (United States)

    Zhao, Bin; Gao, Lei

    2009-11-23

    The temperature-dependent Goos-Hänchen shift (GHS) for an electromagnetic wave reflected from a metal/dielectric composite material is investigated. With the stationary-phase method, we theoretically show that the effect of the temperature on GHS is significant near the Brewster angle for the dielectric composites and at the grazing angle for the metallic composites. For dielectric composites, the lateral shift can be negative as well as positive. And GHS may become much negative, much positive, and nonmonotonic variation with increasing the temperature under different conditions. Moreover, through the suitable adjustment of the temperature, one may realize the reversal of the GHS. To support the above results, numerical simulations for Gaussian incident beams based on the momentum method and COMSOL Multiphysics software are provided, and reasonable agreement between the theoretical results and numerical simulations is found.

  11. Polydopamine tethered enzyme/metal-organic framework composites with high stability and reusability

    Science.gov (United States)

    Wu, Xiaoling; Yang, Cheng; Ge, Jun; Liu, Zheng

    2015-11-01

    An enzyme/metal-organic framework (MOF) composite with both highly stable and easily reusable features was prepared via tethering enzyme/MOF nanocrystals with polydopamine (PDA). The micrometer-sized PDA tethered enzyme/MOF composite can be easily repeatedly used without obvious activity loss, promising for efficient enzymatic catalysis at low cost with long-term operational stability under harsh conditions.An enzyme/metal-organic framework (MOF) composite with both highly stable and easily reusable features was prepared via tethering enzyme/MOF nanocrystals with polydopamine (PDA). The micrometer-sized PDA tethered enzyme/MOF composite can be easily repeatedly used without obvious activity loss, promising for efficient enzymatic catalysis at low cost with long-term operational stability under harsh conditions. Electronic supplementary information (ESI) available: Synthesis of enzyme-MOF nanocrystals, SEM, TEM, CLSM characterization and measurements of enzymatic performances. See DOI: 10.1039/c5nr05190h

  12. Theoretical Investigation of Negative Refraction in Metallic and Ferromagnetic Composites

    Institute of Scientific and Technical Information of China (English)

    SU Hua; LI Cheng-fang

    2004-01-01

    A new design of LHM (left-handed material) is suggested, in which the wave vector k and the energy flow S (the Poynting vector) are in the opposite direction. Metallic cores or lines are coated with ferromagnetic layers to obtain negative permittivity and permeability. This design may bring some improvements over the binary design, such as higher homogeneity, smaller volume size, lower power loss, higher convenience and economy. The analytical expressions for the permittivity ε and permeability μ are shown to be negative in certain direction and frequency regions. Two specific structures are theoretically discussed and proved to be left-handed.

  13. Ductilizing Bulk Metallic Glass Composite by Tailoring Stacking Fault Energy

    Science.gov (United States)

    Wu, Y.; Zhou, D. Q.; Song, W. L.; Wang, H.; Zhang, Z. Y.; Ma, D.; Wang, X. L.; Lu, Z. P.

    2012-12-01

    Martensitic transformation was successfully introduced to bulk metallic glasses as the reinforcement micromechanism. In this Letter, it was found that the twinning property of the reinforcing crystals can be dramatically improved by reducing the stacking fault energy through microalloying, which effectively alters the electron charge density redistribution on the slipping plane. The enhanced twinning propensity promotes the martensitic transformation of the reinforcing austenite and, consequently, improves plastic stability and the macroscopic tensile ductility. In addition, a general rule to identify effective microalloying elements based on their electronegativity and atomic size was proposed.

  14. Measuring the noble metal and iodine composition of extracted noble metal phase from spent nuclear fuel using instrumental neutron activation analysis.

    Science.gov (United States)

    Palomares, R I; Dayman, K J; Landsberger, S; Biegalski, S R; Soderquist, C Z; Casella, A J; Brady Raap, M C; Schwantes, J M

    2015-04-01

    Masses of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis. Nuclide presence is predicted using fission yield analysis, and radionuclides are identified and the masses quantified using neutron activation analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared.

  15. Design feasibility study of a divertor component reinforced with fibrous metal matrix composite laminate

    Energy Technology Data Exchange (ETDEWEB)

    You, J.-H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)]. E-mail: j.h.you@ipp.mpg.de

    2005-01-01

    Fibrous metal matrix composites possess advanced mechanical properties compared to conventional alloys. It is expected that the application of these composites to a divertor component will enhance the structural reliability. A possible design concept would be a system consisting of tungsten armour, copper composite interlayer and copper heat sink where the composite interlayer is locally inserted into the highly stressed domain near the bond interface. For assessment of the design feasibility of the composite divertor concept, a non-linear multi-scale finite element analysis was performed. To this end, a micro-mechanics algorithm was implemented into a finite element code. A reactor-relevant heat flux load was assumed. Focus was placed on the evolution of stress state, plastic deformation and ductile damage on both macro- and microscopic scales. The structural response of the component and the micro-scale stress evolution of the composite laminate were investigated.

  16. Compressive behavior and energy absorption of metal porous polymer composite with interpenetrating network structure

    Institute of Scientific and Technical Information of China (English)

    LIU Yu; GONG Xiao-lu

    2006-01-01

    Interpenetrating phase composites (IPCs) are a new class of composite materials with improved combinations of mechanical and physical properties. This study was performed on a new type of IPC called metal porous polymer composite (MPPC) with an interpenetrating network structure. Aluminum-polypropylene (Al-PE) and Aluminum-epoxy resin (Al-Ep) composites were produced by infiltrating the polymer in the aluminum foam. The composite microstructures were characterized using SEM observation. The compressive behavior and energy absorption characteristics of MPPC were investigated and compared with the aluminum foams. The compressive modulus of composite was compared with the VOIGT-REUSS bounds and HASHIN-SHTRIKMAN (H-S) bounds models. The experimental modulus of compressive tests falls well within the theoretical models.

  17. Porous polymer networks and ion-exchange media and metal-polymer composites made therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G.; Katsoulidis, Alexandros

    2016-10-18

    Porous polymeric networks and composite materials comprising metal nanoparticles distributed in the polymeric networks are provided. Also provided are methods for using the polymeric networks and the composite materials in liquid- and vapor-phase waste remediation applications. The porous polymeric networks, are highly porous, three-dimensional structures characterized by high surface areas. The polymeric networks comprise polymers polymerized from aldehydes and phenolic molecules.

  18. Metal coated functionalized single-walled carbon nanotubes for composite applications

    Science.gov (United States)

    Zeng, Qiang

    This study is considered as a method for producing multifunctional composite materials by using metals coated Single-walled Carbon Nanotubes (SWCNTs). In this research, various metals (Ni, Cu, Ag) were successfully deposited onto the surface of SWCNTs. It has been found that homogenous dispersion and dense nucleation sites are the necessary conditions to form uniform coatings on SWCNTs. Functionalization has been applied to achieve considerable improvement in the dispersion of purified SWCNTs and creates more nucleation sites for subsequent metal deposition. A three-step electroless plating approach was used and the coating mechanism is described in the paper. The samples were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). Bulk copper/aluminum-SWNT composites were processed by powder metallurgy with wet mixing techniques. Coated SWCNTs were well dispersed in the metal matrix. Cold pressing followed by sintering was applied to control porosity. The relationships between hardness and SWCNTs addition were discussed. Ni-SWCNTs composite coatings were prepared by electro-composite deposition. SWCNTs were suspended in a Ni deposition electrolyte and deposited together with nickel during electrodeposition. SWCNTs concentrations in the coatings were found to be related to the SWCNTs concentration in the solution, current density and agitation rate. The microstructure of the coatings has been examined by electron microscopy. Ni coated SWCNTs were also incorporated into the high temperature Bismaleimide (BMI)/graphite composite to improve Electromagnetic Interference (EMI) shielding and surface conductivity. The vacuum assisted resin transfer molding (VARTM) was used to process these composites. Surface and volume resistivity and EMI shielding effectiveness of the composites

  19. Application of CO2-TPD in the Synthesis of Composite Oxides from Metal-Organic Precursors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecules as precursors. Based on the CO2-TPD results, it was found that calcination condition had deep effect on the carbonate formation and the minimum firing temperature to acquire pure phase composite oxide. An optimized calcination schedule was then developed.

  20. Swelling compositions based polycarboxylic acids and bentonite clays in solutions of salts of metals

    Directory of Open Access Journals (Sweden)

    A. Sarshesheva

    2012-12-01

    Full Text Available This work is devoted to the synthesis of chemical cross-linked composite materials made of natural inorganic polymer bentonite clay of Manrak deposit, and polyacrylic and polymethacrylic acids. The swelling ability of the composition in solutions of salts of heavy metals (Ni2+ and Pb2+, influence of solution of concentration, pH and temperature on the swelling ability is investigated.

  1. Ac-conductivity and dielectric response of new zinc-phosphate glass/metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Maaroufi, A., E-mail: maaroufi@fsr.ac.ma [University of Mohammed V, Laboratory of Composite Materials, Polymers and Environment, Department of Chemistry, Faculty of Sciences, P.B. 1014, Rabat-Agdal (Morocco); Oabi, O. [University of Mohammed V, Laboratory of Composite Materials, Polymers and Environment, Department of Chemistry, Faculty of Sciences, P.B. 1014, Rabat-Agdal (Morocco); Lucas, B. [XLIM UMR 7252 – Université de Limoges/CNRS, 123 avenue Albert Thomas, 87060 Limoges Cedex (France)

    2016-07-01

    The ac-conductivity and dielectric response of new composites based on zinc-phosphate glass with composition 45 mol%ZnO–55 mol%P{sub 2}O{sub 5}, filled with metallic powder of nickel (ZP/Ni) were investigated by impedance spectroscopy in the frequency range from 100 Hz to 1 MHz at room temperature. A high percolating jump of seven times has been observed in the conductivity behavior from low volume fraction of filler to the higher fractions, indicating an insulator – semiconductor phase transition. The measured conductivity at higher filler volume fraction is about 10{sup −1} S/cm and is frequency independent, while, the obtained conductivity for low filler volume fraction is around 10{sup −8} S/cm and is frequency dependent. Moreover, the elaborated composites are characterized by high dielectric constants in the range of 10{sup 5} for conductive composites at low frequencies (100 Hz). In addition, the distribution of the relaxation processes was also evaluated. The Debye, Cole-Cole, Davidson–Cole and Havriliak–Negami models in electric modulus formalism were used to model the observed relaxation phenomena in ZP/Ni composites. The observed relaxation phenomena are fairly simulated by Davidson–Cole model, and an account of the interpretation of results is given. - Highlights: • Composites of ZnO-P{sub 2}O{sub 5}/metal were investigated by impedance spectroscopy. • Original ac-conductivity behavior was discovered in ZnO-P{sub 2}O{sub 5}/metal composites. • High dielectric constant is measured in ZnO-P{sub 2}O{sub 5}/metal composites. • Dielectric constant as filler function is well interpreted with percolation theory. • Observed relaxation processes are well described using electric modulus formalism.

  2. Influence of mineralogical and heavy metal composition on natural radionuclide concentrations in the river sediments.

    Science.gov (United States)

    Suresh, G; Ramasamy, V; Meenakshisundaram, V; Venkatachalapathy, R; Ponnusamy, V

    2011-10-01

    The natural radiation level has been determined for the sediment samples of the Ponnaiyar River with an aim of evaluating the radiation hazard. The mineralogical characterizations of the sediments have been carried out using the Fourier Transform Infrared (FTIR) spectroscopic technique. The relative distribution of major minerals is determined by calculating extinction coefficient. The concentration and spatial distribution of heavy metals (Pb, Cr, Cu, Zn and Ni) have been studied to understand the heavy metal contamination and its level of toxicity. To evaluate the potential toxicity, heavy metal concentrations are compared with different toxicological and geological reference values. The comparison results suggest that the present metals create an adverse effect on the aquatic ecosystems associated with this river. To assess the sediment contamination due to the studied heavy metals, the Pollution Load Index (PLI) is calculated. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from radioactivity, mineralogical and geochemical analysis to know the existing relations. Obtained results showed that the effect of mineralogy on level of radioactivity should be significant. However, mineralogy effect on heavy metal composition in the sediments should be limited, indicating that other factors such as vicinity of the pollution sources are more important. Also, the influence of mineralogical characterization on level of radioactivity is significant, whereas the influence of the heavy metal composition on level of radioactivity should be limited.

  3. Performance and modeling of active metal-matrix composites manufactured by ultrasonic additive manufacturing

    Science.gov (United States)

    Hahnlen, Ryan; Dapino, Marcelo J.

    2011-04-01

    This paper presents the development and characterization of active aluminum-matrix composites manufactured by Ultrasonic Additive Manufacturing (UAM), an emerging rapid prototyping process based on ultrasonic metal welding. The primary benefit of UAM over other metal-matrix fabrication processes is the low process temperatures, as low as 25 °C. UAM thus provides unprecedented opportunities to develop adaptive structures with seamlessly embedded smart materials and electronic components without degrading the properties that make these materials and components attractive. The objective of this research is to develop UAM composites with aluminum matrices and embedded shape memory NiTi, magnetostrictive Galfenol (FeGa), and polyvinylidene fluoride (PVDF) phases. The paper is focused on the thermally induced strain response and stiffness behavior of NiTi-Al composites, the actuation properties of FeGa-Al composites, and the embedded sensing capabilities of PVDF-Al composites. We observe up to a 10% increase over room temperature stiffness for NiTi-Al composites and a magnetomechanical response in the FeGa-Al composite up to 52.4 μɛ. The response of the PVDF-Al composite to harmonic loads is observed over a frequency range of 10 to 1000 Hz.

  4. Evaluation by Rocket Combustor of C/C Composite Cooled Structure Using Metallic Cooling Tubes

    Science.gov (United States)

    Takegoshi, Masao; Ono, Fumiei; Ueda, Shuichi; Saito, Toshihito; Hayasaka, Osamu

    In this study, the cooling performance of a C/C composite material structure with metallic cooling tubes fixed by elastic force without chemical bonding was evaluated experimentally using combustion gas in a rocket combustor. The C/C composite chamber was covered by a stainless steel outer shell to maintain its airtightness. Gaseous hydrogen as a fuel and gaseous oxygen as an oxidizer were used for the heating test. The surface of these C/C composites was maintained below 1500 K when the combustion gas temperature was about 2800 K and the heat flux to the combustion chamber wall was about 9 MW/m2. No thermal damage was observed on the stainless steel tubes that were in contact with the C/C composite materials. The results of the heating test showed that such a metallic tube-cooled C/C composite structure is able to control the surface temperature as a cooling structure (also as a heat exchanger) as well as indicated the possibility of reducing the amount of coolant even if the thermal load to the engine is high. Thus, application of this metallic tube-cooled C/C composite structure to reusable engines such as a rocket-ramjet combined-cycle engine is expected.

  5. Strong plasmon coupling in self-assembled superparamagnetic nanoshell chains

    Science.gov (United States)

    Xiong, Min; Jin, Xiulong; Ye, Jian

    2016-02-01

    Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible and infrared wavelengths, which indicates that these chain structures potentially can be used as a common substrate for both surface enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) application. This fabrication method also offers a general strategy alternative to top-down processing that enables the construction of nanostructures for metamaterials, electromagnetic energy transport, and optical waveguide.Construction of ordered patterns of plasmonic nanoparticles is greatly important for nanophotonics relevant applications. We have reported a facile and low-cost magnetic field induced self-assembly approach to construct plasmonic superparamagnetic nanoshell (SN) chains up to several hundred micrometers in a few seconds in a large area without templates or other assistance processes. Experimental and theoretical investigations of the near- and far-field optical properties indicate that the super- and sub-radiant modes of the SN chains continuously redshift with the increase of SN number and the Fano resonance emerges in the infinite double- and triple-line SN chains. Strong plasmon coupling effects in the SN chains result in great electric field enhancements at visible

  6. A Facile Approach to the Synthesis of Gold Nanoshells with Near Infrared Responsive Properties

    Institute of Scientific and Technical Information of China (English)

    LIU Shunying; LIANG Zhongshi; GAO Feng; YU Jiahui; LUO Shufang; CALATA Jesus N.; LU Guoquan

    2009-01-01

    A very detailed study of the most important parameters that involved in the preparation of gold nanosheils with near infrared (NIR) absorption properties is reported. The importance of this work lies in the deep understanding of how each parameter contributes to the formation of gold nanoshells in terms of size, shell thickness, optical prop-erty and particle stability, which have not been emphasized in the literatures. Through detailed characterization by UV-Vis spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analysis, a fac-ile approach to synthesize nanoshells with optimal optical properties in the NIR region was obtained. The amount of reagents, the ratio and condition of reagents, the reaction time, all played important roles in the formation of stable,narrow-size distributed gold nanoshells with NIR absorption properties, which have significant applications to pho-tothermal therapy of cancers in biomedical area.

  7. A solid-phase dot assay using silica/gold nanoshells

    Directory of Open Access Journals (Sweden)

    Zharov Vladimir

    2006-01-01

    Full Text Available AbstractWe report on the first application of silica-gold nanoshells to a solid-phase dot immunoassay. The assay principle is based on staining of a drop (1 µl analyte on a nitrocellulose membrane strip by using silica/gold nanoshells conjugated with biospecific probing molecules. Experimental example is human IgG (hIgG, target molecules and protein A (probing molecules. For usual 15-nm colloidal gold conjugates, the minimal detectable amount of hIgG is about 4 ng. By contrast, for nanoshell conjugates (silica core diameter of 70 nm and gold outer diameter of 100 nm we have found significant increase in detection sensitivity and the minimal detectable amount of hIgG is about 0.5 ng. This finding is explained by the difference in the monolayer particle extinction.

  8. Layer-by-layer synthesis of mechanically robust solvent-permeable silica nanoshells.

    Science.gov (United States)

    Whitaker, Kathryn A; Furst, Eric M

    2014-01-21

    A layer-by-layer (LbL) synthesis of mechanically robust micrometer-diameter nanoshell silica was developed. Silica was templated onto polstyrene latex particles using a modified Stöber synthesis. Each subsequent silica layer was deposited after adsorbing cationic polymer poly(allylamine) hydrochloride. The silica shell grew approximately 30 nm for each reaction step. The polystyrene-silica core-shell particles were calcined at 500 °C to remove the latex core. The synthesis was adapted to nonspherical shapes using anisotropic polystyrene dicolloids as templates. The silica nanoshells were functionalized to render them organophilic or fluorescent. The rates at which water, ethanol, and aqueous sucrose solution (60% w/w) permeate the silica shells were compared using spectrophotometry and conductivity measurements. The rate of solvent uptake ranged between under 1 h to over 1 week depending on the surface chemistry of the nanoshells.

  9. Surface Plasmon Resonance and Field Enhancement of Au/Ag Alloyed Hollow Nanoshells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li; YU Xue-Feng; FU Xiao-Feng; HAO Zhong-Hua; LI Kai-Yang

    2008-01-01

    We investigate the nanostructure,surface plasmon resonance (SPR) absorption and nonlinear enhancement of Au/Ag alloyed hollow nanoshells prepared by the replacement reaction of Ag nanoparticles in a HAuCl4 aqueous solution.As the volume of HA uCl4 increases from 0 mL to 0.5 mL,the SPR band of the Au/Ag alloyed nanoshells is tuned from 430nm to 780nm,and the third-order nonlinear optical susceptibility is enhanced nearly by an order of magnitude,which indicates a large enhancement of local field in the Au/Ag alloyed hollow nanoshells with hole defects.

  10. Influence of active nano particle size and material composition on multiple quantum emitter enhancements: Their Enhancement and Jamming Effects

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Ziolkowski, Richard W.

    2014-01-01

    of a gain-impregnated silica nano-core covered with a nano-shell of a specific plasmonic material. Attention is devoted to the influence of the over-all size of these particles and their material composition on the obtained levels of active enhancement or jamming. Silver, gold and copper are employed...... levels are most notable when the nano-shell is gold....

  11. Metallic Functionally Graded Materials: A Specific Class of Advanced Composites

    Institute of Scientific and Technical Information of China (English)

    Jerzy J.Sobczak; Ludmil Drenchev

    2013-01-01

    Functionally graded materials,including their characterization,properties and production methods are a new rapidly developing field of materials science.The aims of this review are to systematize the basic production techniques for manufacturing functionally graded materials.Attention is paid to the principles for obtaining graded structure mainly in the metal based functionally graded materials.Several unpublished results obtained by the authors have been discussed briefly.Experimental methods and theoretical analysis for qualitative and quantitative estimation of graded properties have also been presented.The article can be useful for people who work in the field of functionally graded structures and materials,and who need a compact informative review of recent experimental and theoretical activity in this area.

  12. Residual stresses in continuous graphite fiber Al metal matrix composites

    Science.gov (United States)

    Park, Hun Sub; Zong, Gui Sheng; Marcus, Harris L.

    1988-01-01

    The residual stresses in graphite fiber reinforced aluminum (Gr/Al) composites with various thermal histories are measured using X-ray diffraction (XRD) methods. The XRD stress analysis is based on the determination of lattice strains by precise measurements of the interplanar spacings in different directions of the sample. The sample is a plate consisting of two-ply P 100 Gr/Al 6061 precursor wires and Al 6061 overlayers. Prior to XRD measurement, the 6061 overlayers are electrochemically removed. In order to calibrate the relationship between stress magnitude and lattice spacing shift, samples of Al 6061 are loaded at varying stress levels in a three-point bend fixture, while the stresses are simultaneously determined by XRD and surface-attached strain gages. The stresses determined by XRD closely match those determined by the strain gages. Using these calibrations, the longitudinal residual stresses of P 100 Gr/Al 6061 composites are measured for various heat treatments, and the results are presented.

  13. Micromechanical Analysis of Interfacial Debonding in Metal Matrix Composites Subjected to off-axis Loading

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Zhu; Xuefeng Chen; Zhi Zhai; Qiang Chen; Shaohua Tian; Zhengjia He

    2013-01-01

    This study aims to investigate the effects of interfacial debonding and fiber volume fraction on the stress -strain behavior of the fiber reinforced metal matrix composites subjected to off -axis loading .The generalized method of cells ( GMC) is used to analyze a representative element whose fiber shape is circular .The constant compliant interface model (CCI) is also adopted to study the response of composites with imperfect interfacial bonding .Results show that for the com-posites subjected to off-axis loading ,the mechanical behaviors are affected appreciably by the interfacial debonding and the fiber volume fraction .

  14. MS&T'13 Symposium Preview: Metal and Polymer Matrix Composites

    Science.gov (United States)

    Gupta, Nikhil; Paramsothy, Muralidharan

    2013-08-01

    The Metal and Polymer Matrix Composites symposium at Materials Science & Technology 2013 (MS&T'13) conference is planned to provide a platform to researchers working on various aspects of composite materials and capture the state of the art in this area. The dialogue among leading researchers is expected to provide insight into the future of this field and identify the future directions in terms of research, development, and applications of composite materials. In the 2 day program, the symposium includes 34 presentations, including 10 invited presentations. The contributions have come from 16 different countries including USA, Mexico, Switzerland, India, Egypt, and Singapore.

  15. An engineering analysis of penetration of metal ball into fibre-reinforced composite targets

    Institute of Scientific and Technical Information of China (English)

    Yong-chi LI; Zhi-hai WANG; Xiao-jun WANG; Xiu-zhang HU

    2009-01-01

    An engineering analysis of computing the penetration problem of a steel ball penetrating into fibre-reinforced composite targets is presented. Assume the metal ball is a rigid body, and the composite target is a transversely isotropic elasto-plastic material. In the analysis, a spherical cavity dilatation model is incorporated in the cylindrical cavity penetration method. Simulation results based on the modified model are in good agreement with the results for 3-D Kevlar woven (3DKW) composite anti-penetration experiments. Effects of the target material parameters and impact parameters on the penetration problem are also studied.

  16. Nanoshell-mediated photothermal therapy can enhance chemotherapy in inflammatory breast cancer cells.

    Science.gov (United States)

    Fay, Brittany L; Melamed, Jilian R; Day, Emily S

    2015-01-01

    Nanoshell-mediated photothermal therapy (PTT) is currently being investigated as a standalone therapy for the treatment of cancer. The cellular effects of PTT include loss of membrane integrity, so we hypothesized that nanoshell-mediated PTT could potentiate the cytotoxicity of chemotherapy by improving drug accumulation in cancer cells. In this work, we validated our hypothesis using doxorubicin as a model drug and SUM149 inflammatory breast cancer cells as a model cancer subtype. In initial studies, SUM149 cells were exposed to nano-shells and near-infrared light and then stained with ethidium homodimer-1, which is excluded from cells with an intact plasma membrane. The results confirmed that nanoshell-mediated PTT could increase membrane permeability in SUM149 cells. In complementary experiments, SUM149 cells treated with nanoshells, near-infrared light, or a combination of the two to yield low-dose PTT were exposed to fluorescent rhodamine 123. Analyzing rhodamine 123 fluorescence in cells via flow cytometry confirmed that increased membrane permeability caused by PTT could enhance drug accumulation in cells. This was validated using fluorescence microscopy to assess intracellular distribution of doxorubicin. In succeeding experiments, SUM149 cells were exposed to subtherapeutic levels of doxorubicin, low-dose PTT, or a combination of the two treatments to determine whether the additional drug uptake induced by PTT is sufficient to enhance cell death. Analysis revealed minimal loss of viability relative to controls in cells exposed to subtherapeutic levels of doxorubicin, 15% loss of viability in cells exposed to low-dose PTT, and 35% loss of viability in cells exposed to combination therapy. These data indicate that nanoshell-mediated PTT is a viable strategy to potentiate the effects of chemotherapy and warrant further investigation of this approach using other drugs and cancer subtypes.

  17. Thermoelectric properties of semiconductor-metal composites produced by particle blending

    Directory of Open Access Journals (Sweden)

    Yu Liu

    2016-10-01

    Full Text Available In the quest for more efficient thermoelectric material able to convert thermal to electrical energy and vice versa, composites that combine a semiconductor host having a large Seebeck coefficient with metal nanodomains that provide phonon scattering and free charge carriers are particularly appealing. Here, we present our experimental results on the thermal and electrical transport properties of PbS-metal composites produced by a versatile particle blending procedure, and where the metal work function allows injecting electrons to the intrinsic PbS host. We compare the thermoelectric performance of composites with microcrystalline or nanocrystalline structures. The electrical conductivity of the microcrystalline host can be increased several orders of magnitude with the metal inclusion, while relatively high Seebeck coefficient can be simultaneously conserved. On the other hand, in nanostructured materials, the host crystallites are not able to sustain a band bending at its interface with the metal, becoming flooded with electrons. This translates into even higher electrical conductivities than the microcrystalline material, but at the expense of lower Seebeck coefficient values.

  18. Thermoelectric properties of semiconductor-metal composites produced by particle blending

    Science.gov (United States)

    Liu, Yu; Cadavid, Doris; Ibáñez, Maria; Ortega, Silvia; Martí-Sánchez, Sara; Dobrozhan, Oleksandr; Kovalenko, Maksym V.; Arbiol, Jordi; Cabot, Andreu

    2016-10-01

    In the quest for more efficient thermoelectric material able to convert thermal to electrical energy and vice versa, composites that combine a semiconductor host having a large Seebeck coefficient with metal nanodomains that provide phonon scattering and free charge carriers are particularly appealing. Here, we present our experimental results on the thermal and electrical transport properties of PbS-metal composites produced by a versatile particle blending procedure, and where the metal work function allows injecting electrons to the intrinsic PbS host. We compare the thermoelectric performance of composites with microcrystalline or nanocrystalline structures. The electrical conductivity of the microcrystalline host can be increased several orders of magnitude with the metal inclusion, while relatively high Seebeck coefficient can be simultaneously conserved. On the other hand, in nanostructured materials, the host crystallites are not able to sustain a band bending at its interface with the metal, becoming flooded with electrons. This translates into even higher electrical conductivities than the microcrystalline material, but at the expense of lower Seebeck coefficient values.

  19. Carbon Materials Metal/Metal Oxide Nanoparticle Composite and Battery Anode Composed of the Same

    Science.gov (United States)

    Hung, Ching-Cheh (Inventor)

    2006-01-01

    A method of forming a composite material for use as an anode for a lithium-ion battery is disclosed. The steps include selecting a carbon material as a constituent part of the composite, chemically treating the selected carbon material to receive nanoparticles, incorporating nanoparticles into the chemically treated carbon material and removing surface nanoparticles from an outside surface of the carbon material with incorporated nanoparticles. A material making up the nanoparticles alloys with lithium.

  20. Thermomechanically induced residual strains in Al/SiCp metal-matrix composites

    DEFF Research Database (Denmark)

    Lorentzen, T.; Clarke, A.P.

    1998-01-01

    Residual lattice strains in the aluminium and SiC phases of F3S.20S extruded A359 20% SiC metal-matrix composite were measured by using neutron diffi action at room and elevated temperatures to monitor the effects of in situ uniaxial plastic deformations. The results are interpreted with referenc...

  1. Thermal conductivity and interfacial conductance of AlN particle reinforced metal matrix composites

    Science.gov (United States)

    Kida, M.; Weber, L.; Monachon, C.; Mortensen, A.

    2011-03-01

    Aluminum nitride (AlN) particle reinforced metal-matrix-composites produced by pressure infiltration are characterized in terms of their thermal conductivity. The composites are designed to cover a wide range of phase contrast between the dispersed particles and the matrix; this is achieved by changing the matrix conductivity using Cu, Al, Sn, and Pb as the matrix. The interface thermal conductance (hc) between AlN and the matrix metals is determined by varying the size of the AlN particles using the Hasselman-Johnson approach and the differential effective medium (DEM) model to calculate hc from measured composite conductivity values. In addition, hc is measured directly at the AlN/Al interface using the transient thermoreflectance (TTR) method on thin aluminum layers deposited on flat AlN substrates to find good agreement with the value derived directly from Al/AlN composites of variable particle size and thus confirm the approach used here to measure hc. Data from the study show that hc at AlN-metal interfaces increases with the metal/AlN Debye temperature ratio; however, the increase is much less than predicted by currently accepted models.

  2. Synthesis and Characterization of Metal Nanoparticle Embedded Conducting Polymer–Polyoxometalate Composites

    Directory of Open Access Journals (Sweden)

    Kishore PilliSatyananda

    2007-01-01

    Full Text Available AbstractPhosphomolybdate has been employed simultaneously as the oxidizing agent for the monomer polymerization and the reduced polyoxometalate is used as reducing agent for the reduction of metal ions. The composites thus obtained have been characterized and may have many potential applications.

  3. Characterisation of a metal matrix composite produced with laser particle injection

    NARCIS (Netherlands)

    Kloosterman, AB; De Hosson, JTM; Sudarshan, TS; Jeandin, M; Khor, KA

    1998-01-01

    This paper concentrates on the laser particle injection process. TiC, TiN end SiC particles were injected into Ti-6Al-4V, which resulted in the formation of a metal matrix composite with modest dissolution of the added particles. The laser tracks with SIC exhibited a diversity of microstructures

  4. Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Canulescu, Stela

    2014-01-01

    Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO2, Y2O3 and CeO2) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical...

  5. Characterisation of a metal matrix composite produced with laser particle injection

    NARCIS (Netherlands)

    Kloosterman, AB; De Hosson, JTM; Sudarshan, TS; Jeandin, M; Khor, KA

    1998-01-01

    This paper concentrates on the laser particle injection process. TiC, TiN end SiC particles were injected into Ti-6Al-4V, which resulted in the formation of a metal matrix composite with modest dissolution of the added particles. The laser tracks with SIC exhibited a diversity of microstructures wit

  6. Temperature effect on the static behaviour of adhesively-bonded metal skin to composite stiffener

    NARCIS (Netherlands)

    Teixeira De Freitas, S.; Sinke, J.

    2015-01-01

    The purpose of this research is to study the effect of temperature on the static behavior of an hybrid structure consisting of adhesively bonded Fiber Metal Laminate skin to a composite stiffener. This hybrid structure was tested using stiffener pull-off tests, which is a typical set-up used to simu

  7. Robust Joining and Integration Technologies for Advanced Metallic, Ceramic, and Composite Systems

    Science.gov (United States)

    Singh, M.; Shpargel, Tarah; Morscher, Gregory N.; Halbig, Michael H.; Asthana, Rajiv

    2006-01-01

    Robust integration and assembly technologies are critical for the successful implementation of advanced metallic, ceramic, carbon-carbon, and ceramic matrix composite components in a wide variety of aerospace, space exploration, and ground based systems. Typically, the operating temperature of these components varies from few hundred to few thousand Kelvin with different working times (few minutes to years). The wide ranging system performance requirements necessitate the use of different integration technologies which includes adhesive bonding, low temperature soldering, active metal brazing, diffusion bonding, ARCJoinT, and ultra high temperature joining technologies. In this presentation, a number of joining examples and test results will be provided related to the adhesive bonding and active metal brazing of titanium to C/C composites, diffusion bonding of silicon carbide to silicon carbide using titanium interlayer, titanium and hastelloy brazing to silicon carbide matrix composites, and ARCJoinT joining of SiC ceramics and SiC matrix composites. Various issues in the joining of metal-ceramic systems including thermal expansion mismatch and resulting residual stresses generated during joining will be discussed. In addition, joint design and testing issues for a wide variety of joints will be presented.

  8. On the homogenization of metal matrix composites using strain gradient plasticity

    DEFF Research Database (Denmark)

    Azizi, Reza; Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2014-01-01

    The homogenized response of metal matrix composites (MMC) is studied using strain gradient plasticity. The material model employed is a rate independent formulation of energetic strain gradient plasticity at the micro scale and conventional rate independent plasticity at the macro scale. Free...

  9. Wear behavior of gas tunnel type plasma sprayed Zr-based metallic glass composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S., E-mail: yugeswaran@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Suresh, K., E-mail: ksureshphy@gmail.com [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Rao, K.P., E-mail: mekprao@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Subramanian, B., E-mail: subramanianb3@gmail.com [CSIR - Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Zr-based metallic glass composite coatings are prepared by gas tunnel plasma torch. Black-Right-Pointing-Pointer Increasing plasma current increases crystallinity amount and hardness of coatings. Black-Right-Pointing-Pointer Coating produced at 300 A plasma current gives minimum sliding wear rate. Black-Right-Pointing-Pointer Coating produced at higher plasma current gives lower erosive wear rate. - Abstract: Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

  10. Fabrication of WCp/NiBSi metal matrix composite by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Hui, E-mail: penghui@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Liu, Chang [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Guo, Hongbo, E-mail: guo.hongbo@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Yuan, Yuan [Zhuzhou Seed Cemented Carbide Technology Co. Ltd, No. 1099 Xiangda Road, Zhuzhou, Hunan 412000 (China); Gong, Shengkai; Xu, Huibin [School of Materials Science and Engineering, Beihang University (BUAA), No. 37 Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials & Performance (Ministry of Education), Beihang University, No. 37 Xueyuan Road, Beijing 100191 (China)

    2016-06-01

    A blend of NiBSi and WC powders was used as raw material for fabricating a metal matrix composite (MMC) by electron beam melting (EBM). Dense and crack-free microstructure was produced with evenly distributed WC reinforcements. Mechanical properties, including macro- and micro-hardness, flexural strength, impact toughness and compressive strength, were investigated.

  11. Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal-Organic Nanofibrous Gel Composites for Oil Adsorption.

    Science.gov (United States)

    Jayaramulu, Kolleboyina; Geyer, Florian; Petr, Martin; Zboril, Radek; Vollmer, Doris; Fischer, Roland A

    2017-03-01

    A versatile and facile synthetic route toward a ultralight hierarchical poroushybrid composed of metal-organic gels and fluorinated graphene oxide is reported. The composite gels show excellent absorbency of oil and various organic solvents due to their prominent meso/macropores, notable hydrophobicity, and superoleophilicity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Gas Phase Sensing of Alcohols by Metal Organic Framework-Polymer Composite Materials

    NARCIS (Netherlands)

    Sachdeva, Sumit; Koper, Sander J.H.; Sabetghadam, Anahid; Soccol, Dimitri; Gravesteijn, Dirk J.; Kapteijn, Freek; Sudhölter, Ernst J.R.; Gascon, Jorge; Smet, De Louis C.P.M.

    2017-01-01

    Affinity layers play a crucial role in chemical sensors for the selective and sensitive detection of analytes. Here, we report the use of composite affinity layers containing Metal Organic Frameworks (MOFs) in a polymeric matrix for sensing purposes. Nanoparticles of NH2-MIL-53(Al) were dispersed in

  13. Hardfacing of aluminium alloys by means of metal matrix composites produced by laser surface alloying

    CSIR Research Space (South Africa)

    Pityana, SL

    2009-06-01

    Full Text Available Metal matrix composite layers were formed on an aluminium substrate by means of laser surface alloying method. Aluminium 1200 was used as a host material and TiC particles were used as the reinforcement. The microstructure of the modified layer...

  14. Microstructure and wear behaviour of Al/TiB2 metal matrix composite

    CSIR Research Space (South Africa)

    Popoola, AP

    2010-10-01

    Full Text Available Al/TiB2 metal matrix composite (MMCs) was fabricated on aluminium AA1200 with the aim of improving the wear resistance property of the substrate. The characterization of the MMCs was carried out by Optical Microscopy (OM), Scanning Electron...

  15. Sliding wear resistance of metal matrix composite layers prepared by high power laser

    NARCIS (Netherlands)

    Ocelik, Vaclav; Matthews, D; de Hosson, Jeff

    2005-01-01

    Two laser surface engineering techniques, Laser Cladding and Laser Melt Injection (LMI), were used to prepare three different metal matrix composite layers with a thickness of about 1 mm and approximately 25-30% volume fraction of ceramic particles. SiC/Al-8Si, WC/Ti-6Al-4V and TiB2/Ti-6Al-4V layers

  16. A novel biomimetic approach to the design of high-performance ceramic/metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Launey, Maximilien E.; Munch, Etienne; Alsem, Daan Hein; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.

    2009-08-01

    The prospect of extending natural biological design to develop new synthetic ceramic-metal composite materials is examined. Using ice-templating of ceramic suspensions and subsequent metal infiltration, we demonstrate that the concept of ordered hierarchical design can be applied to create fine-scale laminated ceramic-metal (bulk) composites that are inexpensive, lightweight and display exceptional damage-tolerance properties. Specifically, Al{sub 2}O{sub 3}/Al-Si laminates with ceramic contents up to approximately 40 vol% and with lamellae thicknesses down to 10 {micro}m were processed and characterized. These structures achieve an excellent fracture toughness of 40 MPa{radical}m at a tensile strength of approximately 300 MPa. Salient toughening mechanisms are described together with further toughening strategies.

  17. A metallic glass composite: Phase-field simulations and experimental analysis of microstructure evolution

    Energy Technology Data Exchange (ETDEWEB)

    Nestler, B. [Applied Research Center, Karlsruhe University of Applied Sciences, Moltkestrasse 30, D-76133 Karlsruhe (Germany)], E-Mail: britta.nestler@hs-karlsruhe.de; Danilov, D. [Applied Research Center, Karlsruhe University of Applied Sciences, Moltkestrasse 30, D-76133 Karlsruhe (Germany); Bracchi, A. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Huang, Y.-L. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Niermann, T. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Seibt, M. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Schneider, S. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany)

    2007-04-15

    The growth process of a crystalline dendritic solid phase from an undercooled melt in the metallic glass composite Zr-Ti-Nb-Ni-Cu-Be is analyzed by experimental investigations and by adaptive finite element simulations based on a multicomponent phase-field model. The phase transition: L(liquid){yields}S(dendrite)+M(matrix) can be described by considering a pseudo-ternary system of late transition metals A=(Zr, Ti, Nb), of early transition metals B=(Ni, Cu) and of the component C=(Be). Scanning and transmission electron microscopy are employed to experimentally determine structural properties of the two-phase system and to provide concentration distributions of the components across the dendrite/matrix interface. The computed and experimentally observed microstructures, length scales and chemical compositions are in good agreement.

  18. Luminescent, freestanding composite films of Au15 for specific metal ion sensing.

    Science.gov (United States)

    George, Anu; Shibu, E S; Maliyekkal, Shihabudheen M; Bootharaju, M S; Pradeep, T

    2012-02-01

    A highly luminescent freestanding film composed of the quantum cluster, Au(15), was prepared. We studied the utility of the material for specific metal ion detection. The sensitivity of the red emission of the cluster in the composite to Cu(2+) has been used to make a freestanding metal ion sensor, similar to pH paper. The luminescence of the film was stable when exposed to several other metal ions such as Hg(2+), As(3+), and As(5+). The composite film exhibited visual sensitivity to Cu(2+) up to 1 ppm, which is below the permissible limit (1.3 ppm) in drinking water set by the U.S. environmental protection agency (EPA). The specificity of the film for Cu(2+) sensing may be due to the reduction of Cu(2+) to Cu(1+)/Cu(0) by the glutathione ligand or the Au(15) core. Extended stability of the luminescence of the film makes it useful for practical applications.

  19. Gadolinium-conjugated gold nanoshells for multimodal diagnostic imaging and photothermal cancer therapy.

    Science.gov (United States)

    Coughlin, Andrew J; Ananta, Jeyarama S; Deng, Nanfu; Larina, Irina V; Decuzzi, Paolo; West, Jennifer L

    2014-02-12

    Multimodal imaging offers the potential to improve diagnosis and enhance the specificity of photothermal cancer therapy. Toward this goal, gadolinium-conjugated gold nanoshells are engineered and it is demonstrated that they enhance contrast for magnetic resonance imaging, X-ray, optical coherence tomography, reflectance confocal microscopy, and two-photon luminescence. Additionally, these particles effectively convert near-infrared light to heat, which can be used to ablate cancer cells. Ultimately, these studies demonstrate the potential of gadolinium-nanoshells for image-guided photothermal ablation.

  20. A solid-phase dot assay using silica/gold nanoshells

    OpenAIRE

    Zharov Vladimir; Khlebtsov Boris; Dykman Lev; Bogatyrev Vladimir; Khlebtsov Nikolai

    2006-01-01

    AbstractWe report on the first application of silica-gold nanoshells to a solid-phase dot immunoassay. The assay principle is based on staining of a drop (1 µl) analyte on a nitrocellulose membrane strip by using silica/gold nanoshells conjugated with biospecific probing molecules. Experimental example is human IgG (hIgG, target molecules) and protein A (probing molecules). For usual 15-nm colloidal gold conjugates, the minimal detectable amount of hIgG is about 4 ng. By contrast, for na...

  1. Stably Doped Conducting Polymer Nanoshells by Surface Initiated Polymerization.

    Science.gov (United States)

    Li, Junwei; Yoon, Soon Joon; Hsieh, Bao-Yu; Tai, Wanyi; O'Donnell, Matthew; Gao, Xiaohu

    2015-12-09

    Despite broad applications ranging from electronics to biomedical sensing and imaging, a long-standing problem of conducting polymers is the poor resistance to dedoping, which directly affects their signature electrical and optical properties. This problem is particularly significant for biomedical uses because of fast leaching of dopant ions in physiological environments. Here, we describe a new approach to engineer multimodal core-shell nanoparticles with a stably doped conductive polymer shell in biological environments. It was achieved by making a densely packed polymer brush rather than changing its molecular structure. Polyaniline (PANI) was used as a model compound due to its concentrated near-infrared (NIR) absorption. It was grafted onto a magnetic nanoparticle via a polydopamine intermediate layer. Remarkably, at pH 7 its conductivity is ca. 2000× higher than conventional PANI nanoshells. Similarly, its NIR absorption is enhanced by 2 orders of magnitude, ideal for photothermal imaging and therapy. Another surprising finding is its nonfouling property, even outperforming polyethylene glycol. This platform technology is also expected to open exciting opportunities in engineering stable conductive materials for electronics, imaging, and sensing.

  2. Composite metal-hydrogen electrodes for metal-hydrogen batteries. Final report, October 1, 1993--April 15, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Ruckman, M.W.; Strongin, M.; Weismann, H. [and others

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped Nb films, these studies suggested that materials with metal-hydrogen ratios exceeding those of commercially available metal hydride materials and fast hydrogen charging and discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films and multilayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 {mu}m thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for modern electronic devices.

  3. Effects of Metal Composition and Ratio on Peptide-Templated Multimetallic PdPt Nanomaterials.

    Science.gov (United States)

    Merrill, Nicholas A; Nitka, Tadeusz T; McKee, Erik M; Merino, Kyle C; Drummy, Lawrence F; Lee, Sungsik; Reinhart, Benjamin; Ren, Yang; Munro, Catherine J; Pylypenko, Svitlana; Frenkel, Anatoly I; Bedford, Nicholas M; Knecht, Marc R

    2017-02-27

    It can be difficult to simultaneously control the size, composition, and morphology of metal nanomaterials under benign aqueous conditions. For this, bioinspired approaches have become increasingly popular due to their ability to stabilize a wide array of metal catalysts under ambient conditions. In this regard, we used the R5 peptide as a three-dimensional template for formation of PdPt bimetallic nanomaterials. Monometallic Pd and Pt nanomaterials have been shown to be highly reactive toward a variety of catalytic processes, but by forming bimetallic species, increased catalytic activity may be realized. The optimal metal-to-metal ratio was determined by varying the Pd:Pt ratio to obtain the largest increase in catalytic activity. To better understand the morphology and the local atomic structure of the materials, the bimetallic PdPt nanomaterials were extensively studied by transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and pair distribution function analysis. The resulting PdPt materials were determined to form multicomponent nanostructures where the Pt component demonstrated varying degrees of oxidation based upon the Pd:Pt ratio. To test the catalytic reactivity of the materials, olefin hydrogenation was conducted, which indicated a slight catalytic enhancement for the multicomponent materials. These results suggest a strong correlation between the metal ratio and the stabilizing biotemplate in controlling the final materials morphology, composition, and the interactions between the two metal species.

  4. Effects of Metal Composition and Ratio on Peptide-Templated Multimetallic PdPt Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Merrill, Nicholas A.; Nitka, Tadeusz T.; McKee, Erik M.; Merino, Kyle C.; Drummy, Lawrence F.; Lee, Sungsik; Reinhart, Benjamin; Ren, Yang; Munro, Catherine J.; Pylypenko, Svitlana; Frenkel, Anatoly I.; Bedford, Nicholas M.; Knecht, Marc R.

    2017-02-22

    It can be difficult to simultaneously control the size, composition, and morphology of metal nanomaterials under benign aqueous conditions. For this, bio-inspired approaches have become increasing popular due to their ability to stabilize a wide array of metal catalysts under ambient conditions. In this regard, we used the R5 peptide as a 3D template for the formation of PdPt bimetallic nanomaterials. Monometallic Pd and Pt nanomaterials have been shown to be highly reactive towards a variety of catalytic processes, but by forming bimetallic species, increased catalytic activity may be realized. The optimal metal-to-metal ratio was determined by varying the Pd:Pt ratio to obtain the largest increase in catalytic activity. To better understand the morphology and the local atomic structure of the materials, the bimetallic PdPt nanomaterials were extensively studied using transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and pair distribution function analysis. The resulting PdPt materials were determined to form multicomponent nanostructures where the Pt component demonstrated varying degrees of oxidation based upon the Pd:Pt ratio. To test the catalytic reactivity of the materials, olefin hydrogenation was conducted which indicated a slight catalytic enhancement for the multicomponent materials. These results suggest a strong correlation between the metal ratio and the stabilizing biotemplate in controlling the final materials morphology, composition, and the interactions between the two metal species.

  5. Deformation and failure mechanisms in metal matrix composites

    Science.gov (United States)

    Newaz, G.; Majumdar, B. S.

    1991-01-01

    An investigation was undertaken to determine the key deformation mechanisms and their interaction leading to failure of both 0 degree and 90 degree Ti 15-3/SCS-6 laminae under monotonic loading. The experimental results suggest that inelastic deformation in the 0-degree lamina is dominated by plastic deformation and that in the 90-degree lamina is dominated by both fiber-matrix debonding and plasticity. The loading-unloading response, monitoring of Poisson's ratio and microscopy were utilized to identify the key deformation mechanisms. The sequence of deformation mechanisms leading to failure are identified for both the 0 and the 90-degree specimens. The threshold strains for plasticity or damage which are referred to as 'microdeformation' in the 0 deg and 90 deg laminae are approximately 0.004 and 0.002, respectively, at room temperature. These strain levels may be considered critical in initiation based structural design with these composites.

  6. Investigation of Creep Phenomenon in Metal Matrix Composites with Whiskers

    Directory of Open Access Journals (Sweden)

    Vahid Monfared

    2012-09-01

    Full Text Available A new mathematical model based on the exponential, logarithmic and polynomial (mixed functions is presented for determination of some unknowns such as displacement rate in outer surface of unit cell and strain rate of short fiber (whisker composites with elastic fiber in steady state creep under axial loading. In addition, effective factor or effect coefficient is introduced for determination of creep displacement rate in outer surface. Also, radial, axial displacement rates, equivalent and shear stresses will be determined by new method. Aim of this study is using the mathematical modeling instead of time consuming and costly experimental methods. On the other hand, unknowns are determined by polynomial, exponential and logarithmic functions instead of some theories, simply. These analytical results are then validated by the Finite Element Analysis (FEA. Interestingly, good agreements are found between analytical and numerical predictions for creep strain rate and displacement rate.

  7. 核-壳纳米复合材料制备及含铬重金属处理%Preparation Study of Core-Nanoshell Composite Materials and Treatment of Chromium-Containing Heavy Metals

    Institute of Scientific and Technical Information of China (English)

    何晓娜; 车如心; 续小雨

    2014-01-01

    采用一步固相法,制备出以富铁空心微珠为基、稀土掺杂纳米铁氧体为壳的核-壳型纳米复合材料.对所制备样品进行X射线衍射(XRD)、扫描电子显微镜(SEM)和磁性能的表征.结果表明成功制备了核-壳型纳米复合材料,样品的晶粒粒径为30 nm,复合材料两相的交换耦合作用增强,剩磁与矫顽力有所改善,提高了复合材料对重金属阳离子的吸附.采用原子吸收光谱法研究了该复合材料对Cr3+离子的吸附性能,确定了最佳吸附条件.在最佳工艺条件下,该复合材料对含铬重金属的吸附率达到98%以上,有较好的吸附能力,适于推广使用.

  8. PARTICULATE SIZE EFFECTS IN THE PARTICLE-REINFORCED METAL-MATRIX COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    魏悦广

    2001-01-01

    The influences of particle size on the mechanical properties of the particulate metal matrix composite are obviously displayed in the experimental observations. However, the phenomenon can not be predicted directly using the conventional elastic-plastic theory. It is because that no length scale parameters are involved in the conventional theory. In the present research, using the strain gradient plasticity theory, a systematic research of the particle size effect in the particulate metal matrix composite is carried out. The roles of many composite factors, such as: the particle size, the Young's modulus of the particle, the particle aspect ratio and volume fraction, as well as the plastic strain hardening exponent of the matrix material,are studied in detail. In order to obtain a general understanding for the composite behavior, two kinds of particle shapes, ellipsoid and cylinder, are considered to check the strength dependence of the smooth or non-smooth particle surface. Finally,the prediction results will be applied to the several experiments about the ceramic particle-reinforced metal-matrix composites. The material length scale parameter is predicted.

  9. Joining and Integration of Advanced Carbon-Carbon Composites to Metallic Systems for Thermal Management Applications

    Science.gov (United States)

    Singh, M.; Asthana, R.

    2008-01-01

    Recent research and development activities in joining and integration of carbon-carbon (C/C) composites to metals such as Ti and Cu-clad-Mo for thermal management applications are presented with focus on advanced brazing techniques. A wide variety of carbon-carbon composites with CVI and resin-derived matrices were joined to Ti and Cu-clad Mo using a number of active braze alloys. The brazed joints revealed good interfacial bonding, preferential precipitation of active elements (e.g., Ti) at the composite/braze interface. Extensive braze penetration of the inter-fiber channels in the CVI C/C composites was observed. The chemical and thermomechanical compatibility between C/C and metals at elevated temperatures is assessed. The role of residual stresses and thermal conduction in brazed C/C joints is discussed. Theoretical predictions of the effective thermal resistance suggest that composite-to-metal brazed joints may be promising for lightweight thermal management applications.

  10. Metals other than uranium affected microbial community composition in a historical uranium-mining site.

    Science.gov (United States)

    Sitte, Jana; Löffler, Sylvia; Burkhardt, Eva-Maria; Goldfarb, Katherine C; Büchel, Georg; Hazen, Terry C; Küsel, Kirsten

    2015-12-01

    To understand the links between the long-term impact of uranium and other metals on microbial community composition, ground- and surface water-influenced soils varying greatly in uranium and metal concentrations were investigated at the former uranium-mining district in Ronneburg, Germany. A soil-based 16S PhyloChip approach revealed 2358 bacterial and 35 archaeal operational taxonomic units (OTU) within diverse phylogenetic groups with higher OTU numbers than at other uranium-contaminated sites, e.g., at Oak Ridge. Iron- and sulfate-reducing bacteria (FeRB and SRB), which have the potential to attenuate uranium and other metals by the enzymatic and/or abiotic reduction of metal ions, were found at all sites. Although soil concentrations of solid-phase uranium were high, ranging from 5 to 1569 μg·g (dry weight) soil(-1), redundancy analysis (RDA) and forward selection indicated that neither total nor bio-available uranium concentrations contributed significantly to the observed OTU distribution. Instead, microbial community composition appeared to be influenced more by redox potential. Bacterial communities were also influenced by bio-available manganese and total cobalt and cadmium concentrations. Bio-available cadmium impacted FeRB distribution while bio-available manganese and copper as well as solid-phase zinc concentrations in the soil affected SRB composition. Archaeal communities were influenced by the bio-available lead as well as total zinc and cobalt concentrations. These results suggest that (i) microbial richness was not impacted by heavy metals and radionuclides and that (ii) redox potential and secondary metal contaminants had the strongest effect on microbial community composition, as opposed to uranium, the primary source of contamination.

  11. Simplification and improvement of prediction model for elastic modulus of particulate reinforced metal matrix composite

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-ming; PAN Fu-sheng; LU Yun; ZENG Su-min

    2006-01-01

    In this paper, we proposed a five-zone model to predict the elastic modulus of particulate reinforced metal matrix composite. We simplified the calculation by ignoring structural parameters including particulate shape, arrangement pattern and dimensional variance mode which have no obvious influence on the elastic modulus of a composite, and improved the precision of the method by stressing the interaction of interfaces with pariculates and maxtrix of the composite. The five- zone model can reflect effects of interface modulus on elastic modulus of composite. It overcomes limitations of expressions of rigidity mixed law and flexibility mixed law. The original idea of five zone model is to put forward the particulate/interface interactive zone and matrix/interface interactive zone. By organically integrating the rigidity mixed law and flexibility mixed law,the model can predict the engineering elastic constant of a composite effectively.

  12. Determination of metals in composite diet samples by inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Melnyk, Lisa Jo; Morgan, Jeffrey N; Fernando, Reshan; Pellizzari, Edo D; Akinbo, Olujide

    2003-01-01

    A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4-1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0-11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.

  13. Metal separators coated with carbon/resin composite layers for PEFCs

    Energy Technology Data Exchange (ETDEWEB)

    Kitta, Shigehiro [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan); Asktechnica Corp., 1488 Ichikawadaimon, Nishi-yatsushiro 409-3601 (Japan); Uchida, Hiroyuki [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan); Watanabe, Masahiro [Clean Energy Research Center, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan)

    2007-12-31

    A new type of metal separator coated with corrosion-resistant and electronically conductive carbon/resin composite layers has been developed. A flat, stainless steel plate was coated with a thin composite layer, and then ribs were formed of a similar composite over the thin layer as gas flow channels. The composite consisted of graphite, epoxy resin and a phenol hardener. By optimizing the combination and composition of materials, target values for the bulk electric conductivity and the chemical stability in hot water were cleared. The separator pieces exhibited a good corrosion resistance during soaking tests in 0.1 M H{sub 2}SO{sub 4} at 90 C over 2000 h or even at 120 C over 1200 h. The area-specific resistance of the separator coated with the thin protecting layer and the rib layer was less than 13.8 m{omega} cm{sup 2}. (author)

  14. Microstructure and mechanical properties of a novel Zr-based bulk metallic glass composite

    Institute of Scientific and Technical Information of China (English)

    SUN Yufeng; WANG Yuren; GUO Jian; WEI Bingchen; LI Weihuo

    2005-01-01

    Zr48.5Cu46.5Al5 bulk metallic glass (BMG) composites with diameters of 3 and 4 mm were prepared through suction casting in an arc melting furnace by modulating the alloy composition around the monothetic BMG composition of the high glass forming ability. Microstructural characterization reveals that the composites contain micron-sized CuZr phase with martensite structure, as well as nano-sized Zr2Cu crystalline particles and Cu10Zr7 plate-like phase embedded in an amorphous matrix. Room temperature compression tests showed that the composites exhibited significant strain hardening and obvious plastic strain of 7.7% for 3 mm and 6.4% for 4 mm diameter samples, respectively.

  15. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

    Energy Technology Data Exchange (ETDEWEB)

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

    2017-02-07

    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  16. Hot-rolled Process of Multilayered Composite Metal Plate

    Directory of Open Access Journals (Sweden)

    YU Wei

    2017-02-01

    Full Text Available For multi-layer plate, it is a difficult problem to increase product yield rate and improve bonding interface quality. A high yield hot-rolled method of multilayered plate was proposed. The raw strips and plate were fixed by argon arc welding. The combined billet was put into a metal box and vacuum pumped, and then heated and rolled by multi passes at the temperature of 1000-1200℃. The 67 layered plate with the thickness of 2.5mm was successfully produced. The interfacial microstructures and diffusion behavior were investigated and analyzed by optical microscopy and scan electronic microscopy. The tensile and shear strength were tested,and the shear fractures were analyzed. The results show that the multilayered plate yield rate is more than 90% by two steps billet combination method and rolling process optimization. The good bonding interface quality is obtained, the shear strength of multilayered plate reaches 241 MPa. Nickel interlayer between 9Cr18 and 1Cr17 can not only prevent the diffusion of carbon, but also improve the microstructure characteristics.

  17. Dry Sliding Friction and Wear Studies of Fly Ash Reinforced AA-6351 Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    M. Uthayakumar

    2013-01-01

    Full Text Available Fly ash particles are potentially used in metal matrix composites due to their low cost, low density, and availability in large quantities as waste by-products in thermal power plants. This study describes multifactor-based experiments that were applied to research and investigation on dry sliding wear system of stir-cast aluminum alloy 6351 with 5, 10, and 15 wt.% fly ash reinforced metal matrix composites (MMCs. The effects of parameters such as load, sliding speed, and percentage of fly ash on the sliding wear, specific wear rate, and friction coefficient were analyzed using Grey relational analysis on a pin-on-disc machine. Analysis of variance (ANOVA was also employed to investigate which design parameters significantly affect the wear behavior of the composite. The results showed that the applied load exerted the greatest effect on the dry sliding wear followed by the sliding velocity.

  18. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    Institute of Scientific and Technical Information of China (English)

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  19. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  20. Volcanic gas composition, metal dispersion and deposition during explosive volcanic eruptions on the Moon

    Science.gov (United States)

    Renggli, C. J.; King, P. L.; Henley, R. W.; Norman, M. D.

    2017-06-01

    The transport of metals in volcanic gases on the Moon differs greatly from their transport on the Earth because metal speciation depends largely on gas composition, temperature, pressure and oxidation state. We present a new thermochemical model for the major and trace element composition of lunar volcanic gas during pyroclastic eruptions of picritic magmas calculated at 200-1500 °C and over 10-9-103 bar. Using published volatile component concentrations in picritic lunar glasses, we have calculated the speciation of major elements (H, O, C, Cl, S and F) in the coexisting volcanic gas as the eruption proceeds. The most abundant gases are CO, H2, H2S, COS and S2, with a transition from predominantly triatomic gases to diatomic gases with increasing temperatures and decreasing pressures. Hydrogen occurs as H2, H2S, H2S2, HCl, and HF, with H2 making up 0.5-0.8 mol fractions of the total H. Water (H2O) concentrations are at trace levels, which implies that H-species other than H2O need to be considered in lunar melts and estimates of the bulk lunar composition. The Cl and S contents of the gas control metal chloride gas species, and sulfide gas and precipitated solid species. We calculate the speciation of trace metals (Zn, Ga, Cu, Pb, Ni, Fe) in the gas phase, and also the pressure and temperature conditions at which solids form from the gas. During initial stages of the eruption, elemental gases are the dominant metal species. As the gas loses heat, chloride and sulfide species become more abundant. Our chemical speciation model is applied to a lunar pyroclastic eruption model with isentropic gas decompression. The relative abundances of the deposited metal-bearing solids with distance from the vent are predicted for slow cooling rates (<5 °C/s). Close to a volcanic vent we predict native metals are deposited, whereas metal sulfides dominate with increasing distance from the vent. Finally, the lunar gas speciation model is compared with the speciation of a H2O-, CO

  1. Development of damped metal-matrix composites for advanced structural applications. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Updike, C.A.; Bhagat, R.B.

    1990-04-01

    The development of damped metal matrix composite structures for advanced applications has been investigated by the use of two different approaches: (1) the development of metal matrix composites with high intrinsic damping compared to that of the matrix material, and (2) the development of coated metal matrix composites with high structural damping compared to that of the composite substrates. The two different approaches are analyzed in terms of their potential for improved damping and feasibility for structural applications. Damping was measured by the transverse vibration of free-free beams using the bandwidth technique by a laser vibrometer under ambient conditions. The damping measurements were made over a wide range of frequencies (.7 kHz to 25.6 kHz) at low strain amplitudes (10 to the -10 power to 10 to the -7 power). Materials investigated for their tensile stiffness, strength, and damping performance include mechanically alloyed (MA) Aluminum-Magnesium, SiC(p)/Aluminum-Copper (MA), SiC(p)/AL, AL2O3(p)/AL, SiC(W)/AL, planar random Gr/AL, unidirectional Gr/AL and unidirectional SiC(Nicalon)/AL composites. The effects of coatings of high damping metals (nitinol and incramute) on 6061-T6 AL and AL2O3(p)/AL substrates have also been studied. The AL-Mg (MA), SiC(p)/AL (MA), SiC(W)/AL and th AL2O3(p)/AL composites show no significant improvement in damping compared with that of the 6061-T6 AL.

  2. Free vibration analysis of embedded magneto-electro-thermo-elastic cylindrical nanoshell based on the modified couple stress theory

    Science.gov (United States)

    Ghadiri, Majid; Safarpour, Hamed

    2016-09-01

    In this paper, size-dependent effect of an embedded magneto-electro-elastic (MEE) nanoshell subjected to thermo-electro-magnetic loadings on free vibration behavior is investigated. Also, the surrounding elastic medium has been considered as the model of Winkler characterized by the spring. The size-dependent MEE nanoshell is investigated on the basis of the modified couple stress theory. Taking attention to the first-order shear deformation theory (FSDT), the modeled nanoshell and its equations of motion are derived using principle of minimum potential energy. The accuracy of the presented model is validated with some cases in the literature. Finally, using the Navier-type method, an analytical solution of governing equations for vibration behavior of simply supported MEE cylindrical nanoshell under combined loadings is presented and the effects of material length scale parameter, temperature changes, external electric potential, external magnetic potential, circumferential wave numbers, constant of spring, shear correction factor and length-to-radius ratio of the nanoshell on natural frequency are identified. Since there has been no research about size-dependent analysis MEE cylindrical nanoshell under combined loadings based on FSDT, numerical results are presented to be served as benchmarks for future analysis of MEE nanoshells using the modified couple stress theory.

  3. Dual energy CT inspection of a carbon fibre reinforced plastic composite combined with metal components

    Directory of Open Access Journals (Sweden)

    Daniel Vavrik

    2016-11-01

    Full Text Available This work is focused on the inspection of carbon fibre reinforced plastic composites (CFRP combined with metal components. It is well known that the high absorption of metallic parts degrades the quality of radiographic measurements (contrast and causes typical metal artefacts in X-ray computed tomography (CT reconstruction. It will be shown that these problems can be successfully solved utilizing the dual energy CT method (DECT, which is typically used for the material decomposition of complex objects. In other words, DECT can help differentiate object components with a similar overall attenuation or visualise low attenuation components that are next to high attenuation ones. The application of DECT to analyse honeycomb sandwich panels and CFRP parts joined with metal fasteners will be presented in the article.

  4. Study of Coating Geometries and Photoluminescence Properties of Metal Nanoparticles/Graphite Composites

    Directory of Open Access Journals (Sweden)

    Pasquale Barone

    2014-01-01

    Full Text Available In this work we present the results of a study of growth and characterization of metal nanoparticles (Ag, Au, and Co/carbon surfaces. The nanoparticles grew by laser ablation technique and their dimensions were controlled by light scattering study and AFM microscopy before their insertion on graphite surface. Nanoparticles appear randomly disposed on carbon surfaces aggregating to form big particles only in the case of silver. The different behavior of metal nanoparticles on carbon surface was explained in terms of different metal wetting of surface, in agreement with previous theoretical results of He et al. Chemical information, obtained by X-ray photoelectron spectroscopy, indicated that the doping process is a simple physisorption while the interfacial interaction between particles and carbon layers causes local defects in graphite structure and the appearance of a strong photoluminescence signal for all composites. Moreover, the visible optical absorption decreases about 10% indicating the progressive metallization of carbon surface.

  5. The Composites of Graphene Oxide with Metal or Semimetal Nanoparticles and Their Effect on Pathogenic Microorganisms

    Directory of Open Access Journals (Sweden)

    Lukas Richtera

    2015-05-01

    Full Text Available The present experiment describes a synthesis process of composites based on graphene oxide, which was tested as a carrier for composites of metal- or metalloid-based nanoparticles (Cu, Zn, Mn, Ag, AgP, Se and subsequently examined as an antimicrobial agent for some bacterial strains (Staphylococcus aureus (S. aureus, methicillin-resistant Staphylococcus aureus (MRSA and Escherichia coli (E. coli. The composites were first applied at a concentration of 300 µM on all types of model organisms and their effect was observed by spectrophotometric analysis, which showed a decrease in absorbance values in comparison with the control, untreated strain. The most pronounced inhibition (87.4% of S. aureus growth was observed after the application of graphene oxide composite with selenium nanoparticles compared to control. Moreover, the application of the composite with silver and silver phosphate nanoparticles showed the decrease of 68.8% and 56.8%, respectively. For all the tested composites, the observed antimicrobial effect was found in the range of 26% to 87.4%. Interestingly, the effects of the composites with selenium nanoparticles significantly differed in Gram-positive (G+ and Gram-negative (G− bacteria. The effects of composites on bacterial cultures of S. aureus and MRSA, the representatives of G+ bacteria, increased with increasing concentrations. On the other hand, the effects of the same composites on G− bacteria E. coli was observed only in the highest applied concentration.

  6. Composite ceramic/metal piston assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Hartsock, D.L.

    1987-03-17

    This patent describes an integrally cast composite assembly of a cylindrical cap attached to a piston having a higher thermal expansion characteristic than the cylindrical cap, the cap being adapted to receive a ceramic insert, comprising: (a) a piston body comprised substantially as a body of revolution about an axis and comprised of a material having a higher thermal expansion characteristic than the cylindrical cap. The piston body has a crown top and an annular crown side wall with an upper edge, and an annular undercut surface terminating the crown side wall. The undercut surface makes an angle with a plane extending perpendicular to the axis and passing through the upper edge of the crown side wall. The angle is substantially equal to the arc tangent of H/R where H is the median distance of the undercut surface from the plane and R is the median radius fo the undercut surface from the axis of the piston; and (b) a cylindrical cap disposed on the piston crown top and having a cap side wall depending about the crown side wall, the cap side wall having an annular lip extending radially inwardly from the cap side wall. The lip has surface mateable with the undercut surface of the piston body so that there exists a tightly stressed camming relationship between the mateable surfaces as a result of the shrinkage of the piston body upon solidification.

  7. Rational composition control of mixed-lanthanide metal-organic frameworks by an interfacial reaction with metal ion-doped polymer substrates

    Science.gov (United States)

    Tsuruoka, Takaaki; Miyanaga, Ayumi; Ohhashi, Takashi; Hata, Manami; Takashima, Yohei; Akamatsu, Kensuke

    2017-09-01

    A simple composition control route to mixed-lanthanide metal-organic frameworks (MOFs) was developed based on an interfacial reaction with mixed-lanthanide metal ion-doped polymer substrates. By controlling the composition of lanthanide ion (Eu3+ and Tb3+) dopants in polymer substrates to be used as metal ion precursors and scaffolding for the formation of MOFs, [EuxTb2-x(bdc)3(H2O)4]n crystals with a tunable metal composition could be routinely prepared on polymer substrates. Inductively coupled plasma (ICP) measurements revealed that the composition of the obtained frameworks was almost the same as that of the initial polymer substrates. In addition, the resulting [EuxTb2-x(bdc)3(H2O)4]n crystals showed strong phosphorescence because of Eu3+ transitions, indicating that the energy transfer from Tb3+ to Eu3+ ions in the frameworks could be achieved with high efficiency.

  8. Self-assembly directed synthesis of poly(ortho-toluidine)-metal(gold and palladium) composite nanospheres.

    Science.gov (United States)

    Reddy, Kakarla Raghava; Lee, Kwang-Pill; Gopalan, Anantha Iyenger

    2007-09-01

    Poly(ortho-toluidine) (POT)-gold (Au) and palladium (Pd) composite nanospheres were successfully synthesized by the reaction of o-toluidine with the corresponding metal (Au or Pd) colloidal solution through self-assembly process in the presence of dodecylbenzenesulfonic acid (DBSA), which acts as both a dopant and surfactant, and ammonium peroxydisulfate as an oxidizing agent. The composites (POT-DBSA/Au or Pd) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, UV-Visible (UV-Vis) spectroscopy, and electrical conductivity measurements. TEM images of the nanocomposites reveal that metal (Au or Pd) nanoparticles were well dispersed on POT spheres. TGA and XRD results show that the composites exhibit high thermal stability and are more crystalline compared with pristine POT. It was found that the electrical conductivity of the POT-DBSA/Au or Pd composites is 2 orders of magnitude higher than that of pristine polymer. Also, the POT-DBSA/Pd composite exhibits magnetic property. The formation mechanism of the POT-DBSA/Au or Pd composite nanosphere is discussed.

  9. Experimental research on the penetration of tungsten-fiber/metallic-glass matrix composite material bullet into steel target

    OpenAIRE

    Chen X.W.; Chen G

    2012-01-01

    In the present paper, the penetration experiments of tungsten-fiber/metallic-glass matrix composite material bullets into 45# steel targets are conducted by employing H25 artillery. In which, an experimental technique of sub-caliber penetration is constructed. The quasi static and dynamic behaviours of tungsten-fiber/metallic-glass matrix composite material are also experimental investigated. The self-sharpening phenomenon of composite material is observed. Integrated with metallographic anal...

  10. Metal-silicate Partitioning and Its Role in Core Formation and Composition on Super-Earths

    Science.gov (United States)

    Schaefer, Laura; Jacobsen, Stein B.; Remo, John L.; Petaev, M. I.; Sasselov, Dimitar D.

    2017-02-01

    We use a thermodynamic framework for silicate-metal partitioning to determine the possible compositions of metallic cores on super-Earths. We compare results using literature values of the partition coefficients of Si and Ni, as well as new partition coefficients calculated using results from laser shock-induced melting of powdered metal-dunite targets at pressures up to 276 GPa, which approaches those found within the deep mantles of super-Earths. We find that larger planets may have little to no light elements in their cores because the Si partition coefficient decreases at high pressures. The planet mass at which this occurs will depend on the metal-silicate equilibration depth. We also extrapolate the equations of state (EOS) of FeO and FeSi alloys to high pressures, and present mass–radius diagrams using self-consistent planet compositions assuming equilibrated mantles and cores. We confirm the results of previous studies that the distribution of elements between mantle and core will not be detectable from mass and radius measurements alone. While observations may be insensitive to interior structure, further modeling is sensitive to compositionally dependent properties, such as mantle viscosity and core freeze-out properties. We therefore emphasize the need for additional high pressure measurements of partitioning as well as EOSs, and highlight the utility of the Sandia Z-facilities for this type of work.

  11. Simulation of stress in an innovative combination of composite with metal sheet

    Science.gov (United States)

    Wróbel, A.; Płaczek, M.; Buchacz, A.; Słomiany, A.

    2016-08-01

    In this article research of stress impact in multi-point connection glass epoxy composite with a metal sheet with a rivet nuts was presented. Composite materials are increasingly used because of the good mechanical properties and low price. The laminates are composites of a layer structure, characterized by very high strength in the direction of the fibers, their weakness is not good toughness in a direction perpendicular to the layers. Mainly checking of displacements and stresses generated on the sheet as a result of pneumatic actuators load for composite boards was carried out. Glass-epoxy composite consisting of four layers of glass mat with a weight of 1000 g/m2 and an epoxy resin and hardener HG700 LG700 volume ratio of 38/100 was created. Next composite was fixed with steel plate with a rivet nuts and bolts. A model of laminate samples and plate was simulate in Siemens NX 8.5 software. The simulation results will determine stresses and displacements in conjunction newly designed composite sheet. Strength analysis was performed with the use of the module NX Advanced Simulation. FEM is an advanced method for solving systems of differential equations, based on the division of the field into finite elements for which the solution is approximated by specific functions, and performing the actual calculations only for nodes of this division. Due to the complexity of the created object to simplify the elements made to reduce the calculation time. This article presents the study of stresses and displacements in the composite plates joined with sheet metal, in summary of this article, the authors compare the obtainted results with the computer simulation results in the article: " The study of fix composite panel and steel plates on testing stand".

  12. METAL MATRIX COMPOSITE BRAKE ROTORS: HISTORICAL DEVELOPMENT AND PRODUCT LIFE CYCLE ANALYSIS

    Directory of Open Access Journals (Sweden)

    M.M. Rahman

    2011-12-01

    Full Text Available Metal matrix composites (MMCs have become attractive for engineering structural applications due to their excellent specific strength and are increasingly seen as an alternative to conventional materials, particularly in the automotive industry. In this study, a historical background on the development and application of metal matrix composites for automotive brake rotors is presented. The discussion also includes an analysis of the product life cycle with stir casting as a case study. The historical review analysis revealed that gradual development of material and processing techniques have led to lighter weight, lower cost and higher performance brake rotors as a result of a better understanding of the mechanics of metal matrix composites. It emerged from the study that the stir casting technique provides ease of operation, sustainability and, most significantly, very competitive costs without sacrificing quality relative to other techniques; as such, it is the most attractive manufacturing process in the industry. These findings can be used for future design and manufacture of an efficient and effective aluminium matrix composite brake rotor for automotive and other applications.

  13. Computation assisted design of favored composition for ternary Mg-Cu-Y metallic glass formation.

    Science.gov (United States)

    Wang, Q; Li, J H; Liu, B X

    2015-06-14

    With the aid of ab initio calculations, a realistic interatomic potential was constructed for the Mg-Cu-Y ternary system under the proposed formalism of smoothed and long-range second-moment approximation of tight-binding. Taking the potential as the starting base, an atomistic computation/simulation route was developed for designing favored and optimized compositions for Mg-Cu-Y metallic glass formation. Simulations revealed that the physical origin of metallic glass formation is the collapse of crystalline lattice when solute concentration exceeds a critical value, thus leading to predict a hexagonal region in the Mg-Cu-Y composition triangle, within which metallic glass formation is energetically favored. It is proposed that the hexagonal region can be defined as the intrinsic glass formation region, or quantitative glass formation ability of the system. Inside the hexagonal region, the driving force for formation of each specific glassy alloy was further calculated and correlated with its forming ability in practice. Calculations pinpointed the optimized stoichiometry in the Mg-Cu-Y system to be Mg64Cu16Y20, at which the formation driving force reaches its maximum, suggesting that metallic glasses designed to have compositions around Mg64Cu16Y20 are most stable or easiest to obtain. The predictions derived directly from the atomistic simulations are supported by experimental observations reported so far in the literature. Furthermore, Honeycutt-Anderson analysis indicated that pentagonal bipyramids (although not aggregating to form icosahedra) dominate in the local structure of the Mg-Cu-Y metallic glasses. A microscopic picture of the medium-range packing can then be described as an extended network of the pentagonal bipyramids, entangled with the fourfold and sixfold disclination lines, jointly fulfilling the space of the metallic glasses.

  14. Enhanced properties of an AA7075 based metal matrix composite prepared using mechanical alloying

    OpenAIRE

    Nazik, C.; Tarakcioglu, N.; Canakci, A.; Varol, T.; , S. Ozkaya

    2014-01-01

    In this study, firstly, AA7075 metal powder which average particle size 43.9 µm were manufactured by using gas atomization method. Thereafter with mechanical alloying method which powder metallurgy manufacturing methods, 10% B4C particle reinforcements that average particle size of 49.5 µm by participating into AA7075 metal matrix composite powder mixtures were prepared. They were milled for different durations (0-8 hrs) in a high energy planetary ball mill. From these milled powders; 550°C a...

  15. Evaluation of shear bond strength of composite resin to nonprecious metal alloys with different surface treatments

    Directory of Open Access Journals (Sweden)

    Yassini E.

    2007-07-01

    Full Text Available Background and Aim: Replacing fractured ceramometal restorations may be the best treatment option, but it is costly. Many different bonding systems are currently available to repair the fractured ceramometal restorations. This study compared the shear bond strength of composite to a base metal alloy using 4 bonding systems.Materials and Methods: In this experimental in vitro study, fifty discs, casted in a Ni-Cr-Be base metal alloy (Silvercast, Fulldent,were ground with 120, 400 and 600 grit sandpaper and divided equally into 5 groups receiving 5 treatments for veneering. Conventional feldspathic porcelain (Ceramco2, Dentsply Ceramco was applied on control group (PFM or group1 and the remaining metal discs were air- abraded for 15 seconds with 50 mm aluminum oxide at 45 psi and washed for 5 seconds under tap water.Then the specimens were dried by compressed air and the  groups were treated with one of the bonding systems as follows: All-Bond 2 (AB, Ceramic Primer (CP, Metal Primer II (MP and Panavia F2 (PF. An opaque composite (Foundation opaque followed by a hybrid composite (Gradia Direct was placed on the treated metal surface and light cured separately. Specimens were stored in distilled water at 370C and thermocycled prior to shear strength testing. Fractured specimens were evaluated under a stereomicroscope. Statistical analysis was performed with one way ANOVA and Tukey HSD tests. P<0.05 was considered as the level of significance.Results: Mean shear bond strengths of the groups in MPa were as follows: PFM group 38.6±2, All-Bond 2 17.06±2.85, Ceramic Primer 14.72±1.2, Metal Primer II 19.04±2.2 and Panavia F2 21.37±2.1. PFM group exhibited the highest mean shear bond strength and Ceramic Primer showed the lowest. Tukey's HSD test revealed the mean bond strength of the PFM group to be significantly higher than the other groups (P<0.001. The data for the PF group was significantly higher than AB and CP groups (P<0.05 and the shear

  16. Electrochemical corrosion of a noble metal-bearing alloy-oxide composite

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X; Ebert, W. L.; Indacochea, Ernesto

    2017-08-01

    The effects of added Ru and Pd on the microstructure and electrochemical behaviour of a composite material made by melting those metals with AISI 410 stainless steel, Zr, Mo, and lanthanide oxides were assessed using electrochemical and microscopic methods The lanthanide oxides reacted with Zr to form durable lanthanide zirconates and Mo alloyed with steel to form FeMoCr intermetallics. The noble metals alloyed with the steel to provide solid solution strengthening and inhibit carbide/nitride formation. A passive film formed during electrochemical tests in acidic NaCl solution, but became less effective as corrosion progressed and regions over the intermetallics eventually failed.

  17. Correlation of mechanical properties with nondestructive evaluation of babbitt metal/bronze composite interface

    Science.gov (United States)

    Ijiri, Y.; Liaw, P. K.; Taszarek, B. J.; Frohlich, S.; Gungor, M. N.

    1988-09-01

    Interfaces of the babbitt metal-bronze composite were examined ultrasonically and were fractured using the Chalmers test method. It was found that the ultrasonic results correlated with the bond strength, the ductility, and the degree of bonding at the tested interface. Specifically, high ultrasonic reflection percentages were associated with low bond strength, low ductility, and low percentages of bonded regions. The fracture mechanism in the bonded area of the babbitt-bronze interface is related to the presence of the intermetallic compound, Cu6Sn5, at the interface. It is suggested that the non-destructive ultrasonic technique can detect the bond integrity of babbitted metals.

  18. Effect of stainless steel chemical composition on brazing ability of filler metal

    Science.gov (United States)

    Miyazawa, Yasuyuki; Ohta, Kei; Nishiyama, Akira

    2014-08-01

    Many kinds of stainless steel have been used in the engineering field. So it is necessary to investigate the effect of SUS chemical compositions on the brazing ability of filler metal. In this study, SUS315J containing Cr, Ni, Si, Cu, and Mo was employed as a base metal. Excellent spreading ability of the molten nickel-based brazing filler on SUS315J was obtained as compared with that on SUS316. Copper and silicon influenced the significant spreading ability of the filler.

  19. Effect of correlation length between metallic nanoparticles in nonlinear properties of composition of oxide glass and metallic nanoparticles using SPFT

    Directory of Open Access Journals (Sweden)

    F. Naseri

    2014-03-01

    Full Text Available There is a kind of composite materials made up of noble metal nanoparticles (such as gold, silver, copper and a dielectric material (such as silica with unique properties. In this paper, using Strong Permittivity Fluctuation Theory (SPFT method, the coefficient of effective permittivity and the effective susceptibility coefficient are calculated for combining glass with metal nanoparticles, assuming that the nanoparticles are spherical. Coefficient of effective permittivity and the effective susceptibility index are estimated for the sample of homogeneous composite materials. And the results of this study are compared with experimental results and other models. It is observed that the data obtained for the zero-order estimate do not match the experimental results. By appropriate correlation length for the second- and third-order, specially for the second-order estimate of SPFT method, conformity between results can be established. Therefore, it can be concluded that SPFT method is betler than other models for calculating and improving the properties of the non-linear model.

  20. Evaluation of Johnson-Cook model constants for aluminum based particulate metal matrix composites

    Science.gov (United States)

    Hilfi, H.; Brar, N. S.

    1996-05-01

    High strain rate and high temperature response of three types of aluminum based particulate metal matrix ceramic composites is investigated by performing split Hopkinson pressure bar (SHPB) experiments. The composites are: NGP-2014 (15% SiC), NGT-6061 (15% SiC), and NGU-6061 (15% Al2O3), in which all the reinforcement materials are percentage by volume. Johnson-Cook constitutive model constants are evaluated from the high strain rate/high temperature data and implemented in a two dimensional finite element computer code (EPIC-2D) to simulate the penetration of an ogive nose tungsten projectile (23 grams) at a velocity 1.17 km/sec into the base 6061-T6 aluminum alloy and the composite NGU-6061. The simulated penetrations in the composite and in 6061-T6 aluminum agree with in 2%, in both materials, with the measured values.

  1. Weibull Probability Model for Fracture Strength of Aluminium (1101)-Alumina Particle Reinforced Metal Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    A.Suresh Babu; V.Jayabalan

    2009-01-01

    In recent times, conventional materials are replaced by metal matrix composites (MMCs) due to their high specific strength and modulus.Strength reliability, one of the key factors restricting wider use of composite materials in various applications, is commonly characterized by Weibull strength distribution function.In the present work, statistical analysis of the strength data of 15% volume alumina particle (mean size 15 μm)reinforced in aluminum alloy (1101 grade alloy) fabricated by stir casting method was carried out using Weibull probability model.Twelve tension tests were performed according to ASTM B577 standards and the test data, the corresponding Weibull distribution was obtained.Finally the reliability of the composite behavior in terms of its fracture strength was presented to ensure the reliability of composites for suitable applications.An important implication of the present study is that the Weibull distribution describes the experimentally measured strength data more appropriately.

  2. Compositional dependence of microstructure and tribological properties of plasma sprayed Fe-based metallic glass coatings

    Institute of Scientific and Technical Information of China (English)

    YANG Qin; LI Ran; LIU ZengQian; SHI MinJie; LUO XueKun; ZHANG Tao

    2012-01-01

    Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters.Microstructures,thermal stabilities and tribological properties of the sprayed coatings were analyzed.The coating performances showed a strong dependence on the intrinsic characters of the compositions,i,e.,glass-forming ability (GFA) and supercooled liquid region (ΔTx).The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger ΔTx.All the coatings exhibited superior wear resistance compared with the substrate.Higher wear resistance could be obtained in coatings with higher amorphous phase fraction,i.e.higher GFA of the composition.This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings.

  3. Synthesis and control of morphology, stoichiometry, and composition of transition metal oxides

    Science.gov (United States)

    Brier, Matthew Isaac

    Transition metal oxides (TMOs) are an important class of materials that have found uses in diverse applications, such as heterogeneous catalysts, sensors, and high temperature superconductors, due to their complex surface chemistry and high mobility of lattice oxygen atoms. Point defects such as oxygen and metal atom vacancies significantly perturb the electronic structure of TMOs and profoundly impact their electrical, optical, ferroelectric, photocatalytic, and other functional properties. As a result, significant research is being done to develop synthesis techniques that can produce metal oxides with controllable material properties. In this thesis, the use of hot wire chemical vapor deposition (HWCVD) was studied with the aim of precisely controlling the morphology, stoichiometry, and composition of TMOs. With molybdenum oxide as the model system, the control of morphology and stoichiometry was achieved by modulation of deposition parameters, such as filament power and gas phase composition. The study of HWCVD of MoOx led to the development of phase diagrams for the dependence of morphology and stoichiometry on deposition parameters. The knowledge gained studying the HWCVD of MoOx was then shown to translate to the deposition of other binary metal oxides by using tungsten, nickel, and vanadium metal filaments to synthesize their respective transition metal oxides. Additionally, NiMoO4 was synthesized as a proof-of-concept to show that HWCVD can be used to make ternary oxides. Nitridation of samples in an ammonia atmosphere was conducted to explore the potential for conversion of HWCVD grown TMOs to their respective metal nitrides, which are also reported to have catalytic properties. To examine the quality of TMOs grown by HWCVD, samples were electrochemically tested for their electrochromic properties and photoactivity with respect to splitting of water.

  4. Dual-frequency plasmon lasing modes in active three-layered bimetallic Ag/Au nanoshells

    Science.gov (United States)

    Wu, DaJian; Wu, XueWei; Cheng, Ying; Jin, BiaoBing; Liu, XiaoJun

    2015-11-01

    The optical properties of three-layered silver-gold-silica (SGS) nanoshells with gain have been investigated theoretically by using Mie theory. Surface plasmon amplification by stimulated emission of radiation (spaser) phenomena can be observed at two plasmon modes of the active SGS nanoshell in the visible region. It is found with the decrease in the radius of the inner Ag core that the critical value of ɛg″(ωg ) for the super-resonance of the low-energy mode increases first and then decreases while that for the high-energy mode decreases. An interesting overlap between the two curves for the critical value of ɛg″(ωg ) can be found at a special core radius. At this point, two super-resonances can be achieved concurrently at the low- and high-energy modes of the active SGS nanoshell with the same gain coefficient. This dual-frequency spaser based on the bimetallic Ag/Au nanoshell may be an efficient candidate for designing the nanolaser.

  5. Au nanomatryoshkas as efficient near-infrared photothermal transducers for cancer treatment: benchmarking against nanoshells.

    Science.gov (United States)

    Ayala-Orozco, Ciceron; Urban, Cordula; Knight, Mark W; Urban, Alexander Skyrme; Neumann, Oara; Bishnoi, Sandra W; Mukherjee, Shaunak; Goodman, Amanda M; Charron, Heather; Mitchell, Tamika; Shea, Martin; Roy, Ronita; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi J; Joshi, Amit

    2014-06-24

    Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm(2) for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy.

  6. Spatiotemporal properties of nanoshell plasmonic response for strong-field experiments

    Science.gov (United States)

    Weber, S. J.; Colas des Francs, G.; Girard, C.

    2015-05-01

    Field enhancement behavior of a SiO2/Au nanoshell is studied in the framework of strong-field physics. Localized plasmonic fields induce local electric field enhancement with the potential to lead to the strong-field regime without the use of costly amplified lasers. In this framework, electrons are tunnel ionized from the nanoshell and accelerated by the local field being spatially inhomogeneous in terms of spectral and polarization properties. These processes are happening within a single laser shot, and thermal effects are therefore neglected. We show that the localized response to ultrashort femtosecond pulses can be investigated by extending Mie theory to multilayer spherical particles. Nanoshell plasmonic resonances can be easily tuned depending on the volume ratio between core and whole particle. Optimum geometric parameters of the nanoshell are selected for use with ultrashort pulses centered at 800 nm where most femtosecond oscillators operate. It is shown that phase and amplitude reshaping of the incident pulse by the plasmonic resonance can be partially corrected using active shaping leading to ultrashort response of the medium. Finally, free electron classical trajectories are calculated to highlight the inhomogeneous nature of the local enhancement in a strong-field picture.

  7. Exact solution for the vibrations of cylindrical nanoshells considering surface energy effect

    Directory of Open Access Journals (Sweden)

    Hessam Rouhi

    2015-12-01

    Full Text Available It has been revealed that the surface stress effect plays an important role in the mechanical behavior ofstructures (such as bending, buckling and vibration when their dimensions are on the order ofnanometer. In addition, recent advances in nanotechnology have proposed several applications fornanoscale shells in different fields. Hence, in the present article, within the framework of surfaceelasticity theory, the free vibration behavior of simply-supported cylindrical nanoshells with theconsideration of the aforementioned effect is studied using an exact solution method. To this end, first,the governing equations of motion and boundary conditions are obtained by an energy-basedapproach. The surface stress influence is incorporated into the formulation according to the Gurtin-Murdoch theory. The nanoshell is modeled according to the first-order shear deformation shell theory.After that, the free vibration problem is solved through an exact solution approach. To this end, thedimensionless form of governing equations is derived and then solved under the simply-supportedboundary conditions using a Navier-type solution method. Selected numerical results are presentedabout the effects of surface stress and surface material properties on the natural frequencies ofnanoshells with different radii and lengths. The results show that the surface energies significantlyaffect the vibrational behavior of nanoshells with small magnitudes of thickness. Also, it is indicatedthat the natural frequency of the nanoshell is dependent of the surface material properties.

  8. Controlled synthesis of multilayered gold nanoshells for enhanced photothermal therapy and SERS detection.

    Science.gov (United States)

    Gao, Yongping; Li, Yongsheng; Wang, Yao; Chen, Yi; Gu, Jinlou; Zhao, Wenru; Ding, Jian; Shi, Jianlin

    2015-01-07

    It can be streamlined: A facile and controllable approach for the fabrication of core/shell-structured multilayer gold nanoshells with uniform nanosize, monodispersity, and tunable plasmonic properties has been successfully developed by utilizing an organosilica layer as the dielectric spacer layer.

  9. Enhanced laser tissue soldering using indocyanine green chromophore and gold nanoshells combination.

    Science.gov (United States)

    Khosroshahi, Mohammad E; Nourbakhsh, Mohammad S

    2011-08-01

    Gold nanoshells (GNs) are new materials that have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes. The purposes of this study were to use the combination of indocyanine green (ICG) and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810 nm diode laser at different power densities. The changes of tensile strength (σ(t)) due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns, and decreasing Vs. It was demonstrated that laser soldering using combination of ICG + GNs could be practical provided the optothermal properties of the tissue are carefully optimized. Also, the tensile strength of soldered skin is higher than skins that soldered with only ICG or GNs. In our case, this corresponds to σ(t) = 1800 g cm(-2) at I ∼ 47 Wcm(-2), T ∼ 85 [ordinal indicator, masculine]C, Ns = 10, and Vs = 0.3 mms(-1).

  10. Nanoembossed gold nanoshell with a fluorescence-like strong SERS signal

    Science.gov (United States)

    Kim, J. H.; Pompa, P. P.; Baek, H. G.; Chung, B. H.

    2016-04-01

    We present a nanoembossed nanoshell with a new internal location for the formation of strong electromagnetic fields. The internally nanoembossed gold nanoshell (AuNS) is fabricated by electrostatically assembling smaller silica nanoparticles (∼15.7 nm) around the silica core (∼123.6 nm) followed by growing gold nanoseeds on the core in a wet process. FDTD calculations reveal the creation of a strong electromagnetic field (|E/Ein|max = 55 at 633 nm) at sharp edges formed by the contact between the nanoembosses and the silica core. The field formation is supported by measuring the SERS signal of Ru(bpy) encapsulated in the nanoembossing silica nanoparticles. SERS signals as strong as the corresponding fluorescence are obtained. The Raman enhancement factor (EF) is estimated to be up to 1010 at 633 nm excitation, in addition to a comparable EF at 785 nm laser excitation. The SERS intensity of the nanoembossed nanoshell layer is sufficiently high compared to the outer or the core of the nanoshell. Finally, we fabricate all-in-one nanoparticles with all the three places where the reporter dyes are loaded and acquire the highest SERS intensity to potentially enable bio-medical applications of the nanoembossed AuNS as a sensitive and reliable labeling particle.

  11. Rigorous buckling analysis of size-dependent functionally graded cylindrical nanoshells

    Science.gov (United States)

    Sun, Jiabin; Lim, C. W.; Zhou, Zhenhuan; Xu, Xinsheng; Sun, Wei

    2016-06-01

    This paper presents new analytical solutions for buckling of carbon nanotubes (CNTs) and functionally graded (FG) cylindrical nanoshells subjected to compressive and thermal loads. The model applies Eringen's nonlocal differential constitutive relation to describe the size-dependence of nanoshells. Based on Reddy's higher-order shear deformation theory, governing equations are established and solved by separating the variables. The analysis first re-examines the classical buckling of single-walled CNTs. Accurate solutions are established, and it is found that the buckling stress decreases drastically when the nonlocal parameter reaches a certain value. For CNTs with constant wall-thickness, the buckling stress eventually decreases with enhanced size effect. By comparing with CNTs molecular dynamic simulations, the obtained nonlocal parameters are much smaller than those proposed previously. Subsequently, FG cylindrical nanoshells are analyzed, and it is concluded that similar behavior that has been observed for CNTs is also valid for FG cylindrical nanoshells. The paper further discusses in detail the effects of different geometric parameters, material distribution, and temperature field.

  12. Percolative metal-organic framework/carbon composites for hydrogen storage

    Science.gov (United States)

    Xie, Shuqian; Hwang, Jiann-Yang; Sun, Xiang; Shi, Shangzhao; Zhang, Zheng; Peng, Zhiwei; Zhai, Yuchun

    2014-05-01

    Percolative Metal-organic framework/Carbon (MOFAC) composites are synthesized by IRMOF8 (isoreticular metal-organic frameworks) directly depositing on activated carbon via heterogeneous nucleation. Carbon content is calculated by TGA (Thermogravimetric analysis) tests. XRD (X-ray diffraction) and FESEM (Field emission-scanning electron microscope) are carried out to characterize the structures of the samples. BET surface areas and the pore size distribution are measured. The dielectric constant is measured with impedance analyzer and a specially designed sample holder. The dielectric constants of the MOFAC composites rise with increasing the carbon content, and the composites possess the insulator-conductor transition as the carbon content increases from 17.77 wt% to 22.2 wt%. The composites are further tested for hydrogen storage capability under assist of the PMN-PT (single crystal lead magnesium niobate-lead titanate) generated electric field. With help from the PMN-PT, the hydrogen uptake capability is increased about 31.5% over the MOFAC3 (MOF-Carbon composite with 22.2 wt% of carbon) without PMN-PT, which is elucidated by the charge distribution mechanisms. The improved storage is due to a stronger electrostatic interaction between IRMOF8 and hydrogen molecule caused by field polarization. Meanwhile, rapid adsorption/desorption kinetics and total reversibility on the samples are observed in the present or absence of external electric field.

  13. MAX Phase Modified SiC Composites for Ceramic-Metal Hybrid Cladding Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yang-Il; Kim, Sun-Han; Park, Dong-Jun; Park, Jeong-Hwan; Park, Jeong-Yong; Kim, Hyun-Gil; Koo, Yang-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    A metal-ceramic hybrid cladding consists of an inner zirconium tube, and an outer SiC fiber-matrix SiC ceramic composite with surface coating as shown in Fig. 1 (left-hand side). The inner zirconium allows the matrix to remain fully sealed even if the ceramic matrix cracks through. The outer SiC composite can increase the safety margin by taking the merits of the SiC itself. In addition, the outermost layer prevents the dissolution of SiC during normal operation. On the other hand, a ceramic-metal hybrid cladding consists of an outer zirconium tube, and an inner SiC ceramic composite as shown in Fig. 1 (right-hand side). The outer zirconium protects the fuel rod from a corrosion during reactor operation, as in the present fuel claddings. The inner SiC composite, additionally, is designed to resist the severe oxidation under a postulated accident condition of a high-temperature steam environment. Reaction-bonded SiC was fabricated by modifying the matrix as the MAX phase. The formation of Ti{sub 3}SiC{sub 2} was investigated depending on the compositions of the preform and melt. In most cases, TiSi{sub 2} was the preferential phase because of its lowest melting point in the Ti-Si-C system. The evidence of Ti{sub 3}SiC{sub 2} was the connection with the pressurizing.

  14. Understanding the Enhanced Catalytic Performance of Ultrafine Transition Metal Nanoparticles–Graphene Composites

    KAUST Repository

    Liu, Xin

    2015-08-11

    Catalysis, as the key to minimize the energy requirement and environmental impact of today\\'s chemical industry, plays a vital role in many fields directly related to our daily life and economy, including energy generation, environment control, manufacture of chemicals, medicine synthesis, etc. Rational design and fabrication of highly efficient catalysts have become the ultimate goal of today\\'s catalysis research. For the purpose of handling and product separation, heterogeneous catalysts are highly preferred for industrial applications and a large part of which are the composites of transition metal nanoparticles (TMNPs). With the fast development of nanoscience and nanotechnology and assisted with theoretical investigations, basic understanding on tailoring the electronic structure of these nanocomposites has been gained, mainly by precise control of the composition, morphology, interfacial structure and electronic states. With the rise of graphene, chemical routes to prepare graphene were developed and various graphene-based composites were fabricated. Transition metal nanoparticles-reduced graphene oxide (TMNPs–rGO) composites have attracted considerable attention, because of their intriguing catalytic performance which have been extensively explored for energy- and environment-related applications to date. This review summarizes our recent experimental and theoretical efforts on understanding the superior catalytic performance of subnanosized TMNPs–rGO composites.

  15. Hopping and Non-universal Conductivity in Half-Metallic CrO2 Composites

    Institute of Scientific and Technical Information of China (English)

    陈亚杰; 张晓渝; 蔡田怡; 李振亚

    2003-01-01

    We study the dependence of resistivity p on conducting volume fraction p in CrO2/TiO2 magnetic composite that is composed of acicular half-metallic particles and spherical insulating particles. The measured percolation threshold was determined to be pc = 0.192. It is found that the conductivity exhibits a non-universal critical exponent t = 2.52 ± 0.08, which may be dominantly attributed to microstructure and higher-order hopping in this composite.

  16. Metallurgical Characterization of the Interfaces and the Damping Mechanisms in Metal Matrix Composites.

    Science.gov (United States)

    2014-09-26

    intrinsic damping behavior needs to be clearly understood and improved if necessary, through metallurgical modifications . In the presnt--tw 4 aa, a graphite...34" * (iv) Recommend microstructural modific ,-..ions to enhance damping in metal matrix composites. - - 4.0 TECHNICAL APPROACH 4.1 Specimen Design A...0.038"xl/0"x4.9 S ecimen; 0.011 Face Sheet Thickness ** Damping Factor _=Ap~g ( log d ec reme n t)L1% ’~A" *1% 5.2.1 Composite Panels (A) Pitch 55 Gr

  17. The application of the eshelby method of internal stress determination to short fibre metal matrix composites

    DEFF Research Database (Denmark)

    Withers, P.J.; Stobbs, W.M.; Pedersen, O.B.

    1989-01-01

    Eshelby's equivalent inclusion approach is used to provide a rigorous theoretical basis for the prediction of the mechanical properties of short fibre composites. The equivalent inclusion construction which is central to this method is described in detail. The elastic, thermoelastic and plastic...... behaviour of short fibre metal matrix composites is predicted, and, taking the Al/SiC system as an example, compared with experiment. Finally, it is shown that relaxation phenomena play an important role in the development of internal stresses, and that the energetics and the resultant stress redistribution...

  18. A static analysis of metal matrix composite spur gear by three-dimensional finite element method

    Science.gov (United States)

    Ganesan, N.; Vijayarangan, S.

    1993-03-01

    A number of engineering components have recently been made using metal matrix composite (MMC) materials, due to their overwhelming advantages, such as light weight high strength, higher dimensional stability and minimal attack by environment, when compared with polymer-based composite materials, even though the cost of MMCs are very high. Power transmission gears are one such area able to make use of MMC materials. Here an attempt is made to study and compare the performance of gears made of MMC materials with that of conventional steel material gears. It may be concluded from this study that MMC materials are highly suitable for making gears that are to transmit even fairly large power.

  19. Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Wang; Zhenxi Guo; Rui Ma; Guojian Hao; Yong Zhang; Junpin Lin; Manling Sui

    2014-01-01

    The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass-matrix composite (MGMC) were investigated by using an in-situ tensile test under transmission electron microscopy (TEM). It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.

  20. Modeling deformation behavior of Cu-Zr-Al bulk metallic glass matrix composites

    Science.gov (United States)

    Pauly, S.; Liu, G.; Wang, G.; Das, J.; Kim, K. B.; Kühn, U.; Kim, D. H.; Eckert, J.

    2009-09-01

    In the present work we prepared an in situ Cu47.5Zr47.5Al5 bulk metallic glass matrix composite derived from the shape memory alloy CuZr. We use a strength model, which considers percolation and a three-microstructural-element body approach, to understand the effect of the crystalline phase on the yield stress and the fracture strain under compressive loading, respectively. The intrinsic work-hardenability due to the martensitic transformation of the crystalline phase causes significant work hardening also of the composite material.