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Sample records for au-ag alloy static

  1. Au-Ag-Cu nano-alloys: tailoring of permittivity

    Science.gov (United States)

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-04-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective.

  2. Au-Ag-Cu nano-alloys: tailoring of permittivity

    Science.gov (United States)

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-01-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

  3. Au-Ag-Cu nano-alloys: tailoring of permittivity.

    Science.gov (United States)

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-01-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

  4. Biosynthesis and stabilization of Au and Au-Ag alloy nanoparticles by fungus, Fusarium semitectum

    International Nuclear Information System (INIS)

    Crystallized and spherical-shaped Au and Au-Ag alloy nanoparticles have been synthesized and stabilized using a fungus, F . semitectum in an aqueous system. Aqueous solutions of chloroaurate ions for Au and chloroaurate and Ag+ ions (1 : 1 ratio) for Au-Ag alloy were treated with an extracellular filtrate of F . semitectum biomass for the formation of Au nanoparticles (AuNP) and Au-Ag alloy nanoparticles (Au-AgNP). Analysis of the feasibility of the biosynthesized nanoparticles and core-shell alloy nanoparticles from fungal strains is particularly significant. The resultant colloidal suspensions are highly stable for many weeks. The obtained Au and Au-Ag alloy nanoparticles were characterized by the surface plasmon resonance (SPR) peaks using a UV-vis spectrophotometer, and the structure, morphology and size were determined by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Possible optoelectronics and medical applications of these nanoparticles are envisaged.

  5. Precipitation hardening of a Cu-free Au-Ag-Pd-In dental alloy

    International Nuclear Information System (INIS)

    The hardening mechanism and related microstructural changes of the Cu-free dental casting alloy composed of Au-Ag-Pd-In was examined by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). The Au-Ag-Pd-In alloy showed apparent age-hardenability. In the SEM photograph, three phases were observed in the solution-treated specimen, that is, the Au-Ag based phase with small amounts of In and Pd as matrix, the InPd phase as particle-like structures, and the Pd-rich phase as lamellar precipitates. By aging the specimen, the very fine Pd-rich inter-granular precipitates grew toward the grain interior as lamellar structure, and finally the coarsened Pd-rich precipitates covered a large part of the Au-Ag based matrix. The hardness increase in the early stage of the age-hardening process was assumed to be caused by the diffusion and aggregation of Pd atoms from the Au-Ag based matrix. The hardness decrease in the later stage of age-hardening process was caused by coarsening of the lamellar precipitates composed of the Pd-rich phase

  6. Phytosynthesis of stable Au, Ag and Au-Ag alloy nanoparticles using J. Sambac leaves extract, and their enhanced antimicrobial activity in presence of organic antimicrobials

    Science.gov (United States)

    Yallappa, S.; Manjanna, J.; Dhananjaya, B. L.

    2015-02-01

    A green chemistry approach for the synthesis of Au, Ag and Au-Ag alloy nanoparticles (NPs) using the corresponding metal precursors and Jasminum sambac leaves extract as both reducing and capping media, under microwave irradiation, is reported. During the formation, as expected, the reaction mixture shows marginal decrease in pH and an increase in solution potential. The formation of NPs is evident from their surface plasmon resonance (SPR) peak observed at ∼555 nm for Au, ∼435 nm for Ag and ∼510 nm for Au-Ag alloy. The XRD pattern shows fcc structure while the FTIR spectra indicate the presence of plant residues adsorbed on these NPs. Such a bio-capping of NPs is characterized by their weight loss, ∼35% due to thermal degradation of biomass, as observed in TG analysis. The colloidal dispersion of NPs is stable for about 6 weeks. The near spherical shape of NPs (ϕ20-50 nm) is observed by FE-SEM/TEM images and EDAX gives the expected elemental composition. Furthermore, these NPs showed enhanced antimicrobial activity (∼1-4-fold increase in zone of inhibition) in combination with antimicrobials against test strains. Thus, the phytosynthesized NPs could be used as effective growth inhibitors for various microorganisms.

  7. Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

    KAUST Repository

    Huang, Jianfeng

    2015-08-13

    Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

  8. Preparation of monolithic foamed Au/Ag alloy with hollow microspheres

    International Nuclear Information System (INIS)

    The polystyrene (PS) microspheres were coated by gold colloid with an average grain size of 4.6 nm by the electrostatic effect, and then electroless plated with gold silver consecutively. The deposited gold layer was 70 to 90 nm thick, almost coating the PS spheres completely. The silver particles deposited subsequently were compact, and larger than the previously de- posited gold particles, forming a 200 to 400 nm-thick layer on the surface of each Au/PS microsphere. The self-supported hollow-sphere Au40 Ag60 alloy was then obtained after the template being removed. Finally, the columniform foamed Au-Ag alloy, 5 mm in diameter, 1.2 g/cm3 in density, was obtained with the hollow spheres of 10 μm diameter after heat treatment. (authors)

  9. Synthesis and Optical Properties of Au-Ag Alloy Nanoclusters with Controlled Composition

    Directory of Open Access Journals (Sweden)

    J. F. Sánchez-Ramírez

    2008-01-01

    Full Text Available Colloidal solid-solution-like Au-Ag alloy nanoclusters of different compositions were synthesized through citrate reduction of mixed metal ions of low concentrations, without using any other protective or capping agents. Optical absorption of the alloy nanoclusters was studied both theoretically and experimentally. The position of the surface plasmon resonance (SPR absorption band of the nanoclusters could be tuned from 419 nm to 521 nm through the variation of their composition. Considering effective dielectric constant of the alloy, optical absorption spectra for the nanoclusters were calculated using Mie theory, and compared with the experimentally obtained spectra. Theoretically obtained optical spectra well resembled the experimental spectra when the true size distribution of the nanoparticles was considered. High-resolution transmission electron microscopy (HREM, high-angle annular dark field (HAADF imaging, and energy dispersive spectroscopy (EDS revealed the true alloy nature of the nanoparticles with nominal composition being preserved. The synthesis technique can be extended to other bimetallic alloy nanoclusters containing Ag.

  10. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    OpenAIRE

    Qi Xu; Fang Liu; Yuxiang Liu; Kaiyu Cui; Xue Feng; , Wei Zhang; Yidong Huang

    2013-01-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The ...

  11. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    Science.gov (United States)

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-07-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  12. Cu-Au-Ag alloy nanoparticles incorporated silica films using a new three-layer deposition technique.

    Science.gov (United States)

    Pal, Sudipto; Bysakh, Sandip; De, Goutam

    2010-02-01

    Formation of Au-Ag-Cu ternary alloy nanoparticles (NPs) is difficult mainly because the system Cu/Ag is immiscible. We present a new synthetic technique to generate such ternary alloy NPs in silica film matrix employing a three-layer (3L) coating design. In this methodology three successive coating layers were deposited on silica glass substrates from separately prepared Cu-, Au- and Ag-ion incorporated inorganic-organic hybrid silica sols by dipping method. The Au layer is kept in the middle because it is miscible with both the Ag and Cu. The 3L film assembly was subjected to UV- and heat-treatment at 450-750 degrees C in H2-N2 atmosphere. UV-treatment generates small Au and Ag NPs in the respective layers and Cu remains as Cu2+; subsequent heat-treatment in H2-N2 induces the formation of ternary alloy NPs by the interlayer diffusion of nanometals. The final heat-treated film (750 degrees C/H2-N2) shows single and sharp plasmon band centered at 480 nm in the UV-visible spectrum indicating the formation of alloy (solid solution) NPs. GIXRD study shows one set of diffraction peaks which are shifted towards higher angle with respect to the Au or Ag diffraction peaks. FESEM, GIXRD, HRTEM, and SAED analyses reveal that the alloy has a composition close to (Au + Ag)0.88Cu0.12. The EDS analyses using the nano probe attached with TEM confirm the presence of Au, Ag and Cu in all the alloy NPs. PMID:20352717

  13. Porous Au-Ag Alloy Particles Inlaid AgCl Membranes As Versatile Plasmonic Catalytic Interfaces with Simultaneous, in Situ SERS Monitoring.

    Science.gov (United States)

    Cao, Qi; Yuan, Kaiping; Liu, Qinghe; Liang, Chongyun; Wang, Xiang; Cheng, Yi-Feng; Li, Qingqing; Wang, Min; Che, Renchao

    2015-08-26

    We present a novel porous Au-Ag alloy particles inlaid AgCl membrane as plasmonic catalytic interfaces with real-time, in situ surface-enhanced Raman spectroscopy (SERS) monitoring. The Au-Ag alloy particles inlaid AgCl membranes were obtained via a facile two-step, air-exposed, and room-temperature immersion reaction with appropriate annealing process. Owing to the designed integration of semiconductor component AgCl and noble metal Au-Ag particles, both the catalytic reduction and visible-light-driven photocatalytic activities toward organic contaminants were attained. Specifically, the efficiencies of about 94% of 4-nitrophenol (4-NP, 5 × 10(-5) M) reduction after 8 min of reaction, and degradation of rhodamine 6G (R6G, 10(-5) M) after 12 min of visible light irradiation were demonstrated. Moreover, efficiencies of above 85% of conversion of 4-NP to 4-aminophenol (4-AP) and 90% of R6G degradation were achieved as well after 6 cycles of reactions, by which robust recyclability was confirmed. Further, with distinct SERS signals generated simultaneously from the surfaces of Au-Ag particles under laser excitation, in situ SERS monitoring of the process of catalytic reactions with superior sensitivity and linearity has been realized. Overall, the capability of the Au-Ag particles inlaid AgCl membranes to provide SERS monitored catalytic and visible-light-driven photocatalytic conversion of organic pollutants, along with their mild and cost-effective fabrication method, would make sense for in-depth understanding of the mechanisms of (photo)catalytic reactions, and also future development of potable, multifunctional and integrated catalytic and sensing devices. PMID:26263301

  14. Bi-SERS sensing and enhancement by Au-Ag bimetallic non-alloyed nanoparticles on amorphous and crystalline silicon substrate.

    Science.gov (United States)

    Tan, Chee Leong; Lee, Soo Kyung; Lee, Yong Tak

    2015-03-01

    We have demonstrated Au-Ag bimetallic non-alloy nanoparticles (BNNPs) on thin a-Si film and c-Si substrate for high SERS enhancement, low cost, high sensitivity and reproducible SERS substrate with bi-SERS sensing properties where two different SERS peak for Au NPs and Ag NPs are observed on single SERS substrate. The isolated Au-Ag bimetallic NPs, with uniform size and spacing distribution, are suitable for uniform high density hotspot SERS enhancement. The SERS enhancement factor of Au-Ag BNNPs is 2.9 times higher compared to Ag NPs on similar substrates due to the increase of the localized surface plasmon resonance effect. However there is a decrement of SERS peak intensity at specific wavenumbers when the surrounding refractive index increases due to out-phase hybridization of Au NPs. The distinct changes of the two different SERS peaks on single Au-Ag BNNPs SERS substrate due to Au and Ag NPs independently show possible application for bi-molecular sensing. PMID:25836846

  15. Ordering fluctuation dynamics in AuAgZn 2

    OpenAIRE

    Livet, Frédéric; Fèvre, Mathieu; Beutier, Guillaume; Sutton, Mark

    2015-01-01

    The second-order ordering transition of the AuAgZn2 alloy has been studied by coherent x-ray scattering. Within a few degrees above the critical temperature Tc, equilibrium critical fluctuations are observed together with some pre-transitional local ordering connected to sample defects. The speckles observed correspond to heterodyne interference between local ordering and fluctuations and show a mixed static and dynamical behaviour in a narrow domain of a few tenths of degree above Tc. The dy...

  16. Local structure of disordered Au-Cu and Au-Ag alloys

    International Nuclear Information System (INIS)

    X-ray-absorption fine structure (XAFS) and x-ray-diffraction (XRD) measurements of disordered alloys AuxCu1-x and Au0.5Ag0.5 prepared by melt spinning were performed. In the Au0.5Ag0.5 alloy, no significant local deviations of the atoms from the average fcc lattice were detected while in AuxCu1-x alloys, significant deviations of atoms from the average fcc lattice were found. Mean-square vibrations of the Cu-Cu distances revealed by the XAFS in AuxCu1-x alloys indicate the weakening of contact between Cu atoms in the dilute limit. Our computer simulation for AuxCu1-x clusters of 105 atoms reproduces the main features of both the XAFS and XRD data

  17. Controlled Synthesis of Au@AgAu Yolk-Shell Cuboctahedra with Well-Defined Facets.

    Science.gov (United States)

    Londono-Calderon, Alejandra; Bahena, Daniel; Yacaman, Miguel J

    2016-08-01

    The synthesis of Au@AgAu yolk-shell cuboctahedra nanoparticles formed by galvanic replacement in a seed-mediated method is described. Initially, single-crystal Au seeds are used for the formation of Au@Ag core-shell nanocubes, which serve as the template material for the deposition of an external Au layer. The well-controlled synthesis yields the formation of cuboctahedra nanoparticles with smooth inner and outer Au/Ag surfaces. The deposition/oxidation process is described to understand the formation of cuboctahedra and octahedra nanoparticles. The Au core maintains the initial morphology of the seed and remains static at the center of the yolk-shell because of residual Ag. Structural analysis of the shell indicates intrinsic stacking faults (SFs) near the surface. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) compositional analysis show an Au-Ag nonordered alloy forming the shell. The three-dimensional structure of the nanoparticles presented open facets on the [111] as observed by electron tomography SIRT reconstruction over a stack of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The geometrical model was validated by analyzing the direction of streaks in coherent nanobeam diffraction (NBD). The catalytic activity was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NTP) by NaBH4 in the presence of Au@AgAu yolk-shell nanoparticles. PMID:27385583

  18. Strong enhancement of the electrochemiluminescence of luminol by AuAg and PtAg alloy nanoclusters, and its sensitization by phenolic artificial oestrogens

    International Nuclear Information System (INIS)

    This paper reports on the synthesis of AuAg and PtAg alloy nanoclusters (NCs) and their enhancement effect on the electrochemiluminescence (ECL) of luminol. The conditions of synthesis were optimized, and the structure and properties of the NCs were characterized by X-ray diffraction, transmission electron microscopy, electrochemistry, and optical spectroscopy. The NCs are found to intensify (by up to 20 times) the ECL of luminol in solution of pH 8.5. This finding can largely extend the useful pH range of the ECL of luminol. The enhanced ECL is strongly affected by oxygen and hydrogen peroxide, and the mechanism of enhancement is attributed to the accelerated production of reactive oxygen species. The enhanced ECL is also affected by phenolic artificial estrogens, and this was used for their determination with detection limits as low as 700 pg L−1 (with AuAg) and 1.6 ng L−1 (with PtAg). The method was applied to the determination of such estrogens in egg samples using diethylstilbestrol as a reference substance. (author)

  19. Au/Ag nanoalloy shells as near-infrared SERS nanoprobe for the detection of protein

    International Nuclear Information System (INIS)

    We provide a highly sensitive, uniform and reproducible surface-enhanced Raman scattering (SERS) performance obtained from the randomly aggregated Au/Ag nanoalloy shells substrate. Au/Ag nanoalloy shells consist of SiO2 core and Au/Ag alloy shells layer. The obtained Au/Ag nanoalloy shells with a monodisperse size distribution exhibit different morphology by the analysis of TEM. By changing the ratio of Au and Ag, the plasmonic extinction of Au/Ag nanoshells varied in near-infrared window region. In this experiment, Au/Ag nanoshells with controllable ratio can obtain larger SERS signals, which can be used for ultrasensitive detection of biomolecules. These SERS-active spheres show interesting properties as a novel Raman tag for immunoassays. (paper)

  20. Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

    Institute of Scientific and Technical Information of China (English)

    M. Vinod; K.G.Gopchandran

    2014-01-01

    Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

  1. Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

    Directory of Open Access Journals (Sweden)

    M. Vinod

    2014-12-01

    Full Text Available Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

  2. Thermodynamic description of Au-Ag-Si ternary system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the available experimental information, the Ag-Si binary system was thermodynamically assessed using the CALPHAD method. The solution phases, including liquid, fcc-Al and diamond-A4, were modeled as substitutional solutions, of which the excess Gibbs energies were expressed by Redlich-Kister polynomial functions. Combined with previous assessment of the Ag-Au and Au-Si binary systems, thermodynamic description of the Au-Ag-Si ternary system was performed to reproduce the reported phase equilibria. Thermodynamic properties of liquid alloys, liquidus projection and several vertical and isothermal sections of this ternary system were calculated, which are in reasonable agreement with the reported experimental data.

  3. Synthesis and photo physical properties of Au - Ag (core - shell) nanoparticles disperse in poly vinyl alcohol matrix

    International Nuclear Information System (INIS)

    Synthesis of core - shell (Au - Ag) nanoparticle with varying silver composition has been carried out in aqueous poly vinyl alcohol (PVA) matrix. Core gold nanoparticle (∼15 nm) has been synthesized through seed-mediated growth process. Synthesis of silver shell with increasing thickness (∼1–5 nm) has been done by reducing Ag+ over the gold sol in the presence of mild reducing ascorbic acid. Characterization of Au - Ag nanoparticles has been done by UV–Vis, High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) spectroscopic study. The blue shift of surface plasmon resonance (SPR) band with increasing mole fraction of silver has been interpreted due to dampening of core, i.e. Au SPR by Ag. The dependence of nonlinear optical response of spherical core - shell nanoparticles has been investigated as a function of relative composition of each metal. Simulation of SPR extinction spectra based on quasi-static theory is done. A comparison of our experimental and the simulated extinction spectra using quasi-static theory of nanoshell suggests that our synthesized bimetallic particles have core - shell structure rather than bimetallic alloy particles.

  4. Spherically-clustered porous Au-Ag alloy nanoparticle prepared by partial inhibition of galvanic replacement and its application for efficient multimodal therapy.

    Science.gov (United States)

    Jang, Hongje; Min, Dal-Hee

    2015-03-24

    The polyvinylpyrrolidone (PVP)-coated spherically clustered porous gold-silver alloy nanoparticle (PVP-SPAN) was prepared by low temperature mediated, partially inhibited galvanic replacement reaction followed by silver etching process. The prepared porous nanostructures exhibited excellent photothermal conversion efficiency under irradiation of near-infrared light (NIR) and allowed a high payload of both doxorubicin (Dox) and thiolated dye-labeled oligonucleotide, DNAzyme (FDz). Especially, PVP-SPAN provided 10 times higher loading capacity for oligonucleotide than conventional hollow nanoshells due to increased pore diameter and surface-to-volume ratio. We demonstrated highly efficient chemo-thermo-gene multitherapy based on codelivery of Dox and FDz with NIR-mediated photothermal therapeutic effect using a model system of hepatitis C virus infected human liver cells (Huh7 human hepatocarcinoma cell line containing hepatitis C virus NS3 gene replicon) compared to conventional hollow nanoshells. PMID:25560916

  5. Phytosynthesis of Au, Ag and Au-Ag bimetallic nanoparticles using aqueous extract and dried leaf of Anacardium occidentale

    Science.gov (United States)

    Sheny, D. S.; Mathew, Joseph; Philip, Daizy

    2011-06-01

    Present study reports a green chemistry approach for the biosynthesis of Au, Ag, Au-Ag alloy and Au core-Ag shell nanoparticles using the aqueous extract and dried powder of Anacardium occidentale leaf. The effects of quantity of extract/powder, temperature and pH on the formation of nanoparticles are studied. The nanoparticles are characterized using UV-vis and FTIR spectroscopies, XRD, HRTEM and SAED analyses. XRD studies show that the particles are crystalline in the cubic phase. The formation of Au core-Ag shell nanoparticles is evidenced by the dark core and light shell images in TEM and is supported by the appearance of two SPR bands in the UV-vis spectrum. FTIR spectra of the leaf powder before and after the bioreduction of nanoparticles are used to identify possible functional groups responsible for the reduction and capping of nanoparticles. Water soluble biomolecules like polyols and proteins are expected to bring about the bio-reduction.

  6. Static and Vibrational Properties of Lithium Alloys

    Directory of Open Access Journals (Sweden)

    Aditya M. Vora

    2011-01-01

    Full Text Available The computations of the static and vibrational properties of four equiatomic lithium alloys viz. Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5 to second order in local model potential is discussed in terms of real-space sum of Born von Karman central force constants. The local field correlation functions due to Hartree (H, Ichimaru-Utsumi (IU and Sarkar et al. (S are used to investigate influence of the screening effects on the aforesaid properties. Results for the lattice constants i.e.С11, С12, С44, С12 – С44, С12/С44 and bulk modulus Å obtained using the Hartree (H local field correction function has higher values in comparison with the results obtained for the same properties using Ichimaru-Utsumi (IU and Sarkar et al. (S local field correction functions. The results for the Shear modulus (С′, deviation from Cauchy’s relation, Poisson’s ratio σ, Young modulus Y, propagation velocity of elastic waves, phonon dispel-rsion curves and degree of anisotropy A are highly appreciable for the four lithium alloys.

  7. PVP induce self-seeding process for growth of Au@Ag core@shell nanocomposites

    Science.gov (United States)

    Eisa, Wael H.; Al-Ashkar, Emad; El-Mossalamy, S. M.; Ali, Safaa S. M.

    2016-05-01

    A novel self-seeding route is developed for fabrication of metallic nanocomposites of gold (core) and silver (shell) (Au@Ag core@shell). Herein, polyvinylpyrrolidone (PVP) is used as both reducing and stabilizing agent. The surface plasmon resonance (SPR) of Au@Ag core@shell can be tuned by controlling the thickness of the Ag shell. The different growth stages of the Au@Ag core@shell have been traced by in situ UV-vis absorption spectra. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy are used for the characterization of the prepared samples.

  8. Strain distributions of confined Au/Ag and Ag/Au nanoparticles

    Institute of Scientific and Technical Information of China (English)

    黄红华; 章英; 刘晓山; 骆兴芳; 袁彩雷; 叶双莉

    2015-01-01

    The strain distributions of Au/Ag and Ag/Au nanoparticles confined in the Al2O3 matrix with different core sizes are investigated by using the finite element method, respectively. The simulation results clearly indicate that the compressive strains exerted on the Au/Ag and Ag/Au nanoparticles can be induced by the Al2O3 matrix. Moreover, it can be found that the strain gradient existing in a Au/Ag nanoparticle is much larger than that in a Ag/Au nanoparticle, which could be due to the larger Young’s modulus of Au than that of Ag. With the core size increasing, the strain gradient existing in the Au/Ag nanoparticle becomes larger, while the strain gradient existing in the Ag/Au nanoparticle keeps constant. These different strain distributions may have significant infl uences on the structures and morphologies of the Au/Ag and Ag/Au nanoparticles, leading to the different physical properties for potential applications.

  9. Spectral Tuning of Plasmon Resonance in a Core/Shell (Au)Ag Nanocomposite

    Science.gov (United States)

    Panarin, A. Yu.; Abakshonok, A. V.; Agabekov, V. E.; Eryomin, A. N.; Terekhov, S. N.

    2015-01-01

    A bimetallic (Au)Ag nanocomposite with a core/shell structure was synthesized in aqueous solution and a H2O/EtOH mixture (1:1) containing polymers (carboxymethylcellulose, sodium polystyrenesulfonate, polyvinylpyrrolidone, dextran). Its structure and optical properties were characterized. The shape and position of scattering bands of colloidal noble-metal nanoparticles with optical density <0.1 were undistorted by solvent absorption. Scattering spectra had to be corrected for solutions of greater optical density. A method for correcting the resonant lightscattering spectra of Au and (Au)Ag nanoparticles was proposed for a single-beam apparatus. The possibility of surface plasmon resonance tuning for (Au)Ag with a short-wavelength shift of ~150 nm for the absorption band maximum and of ~84 nm for the resonant scattering band was demonstrated by varying the AgNO3 concentration during formation of the silver shell on the gold core.

  10. Development of Au-Ag nanowire mesh fabrication by UV-induced approach

    Energy Technology Data Exchange (ETDEWEB)

    Saggar, Siddhartha [Laboratory for Molecular Photonics and Electronics, Department of Physics, National Institute of Technology, Calicut, Kerala, India and School of Nanoscience and Technology, National Institute of Technology, Calicut, Kerala (India); Predeep, Padmanabhan, E-mail: predeep@nitc.ac.in

    2014-10-15

    In an attempt to overcome the limitations of the presently prevailing transparent conducting electrode (TCE) - indium tin oxide (ITO) - many materials have been considered for replacing ITO. Recently, a novel method has been reported for the synthesis of Au-Ag nanowire (NW) mesh, and tested successfully for organic-light-emitting-diodes (OLEDs). It employs UV-induced reduction of gold- and silver- precursors to form Au-Ag NW mesh. In this report, Au-Ag NW mesh thin films are synthesized on glass substrates with an objective for use as facing-electrode for Organic Photovoltaics. Various issues and factors affecting the fabrication-process have been improved, and are also discussed here. The electrode showed good transmitivity, of around 95% (excluding that of glass substrate). The advantage of the technique is its simple processing method and cost-effectiveness.

  11. Static Recrystallization Behavior of Hot Deformed Austenite for Micro-Alloyed Steel

    Institute of Scientific and Technical Information of China (English)

    Jie HUANG; Zhou XU; Xin XING

    2003-01-01

    Static recrystallization behavior of austenite for micro-alloyed steel during hot rolling was studied and the influence (τ-ε diagram) of holding time and deformation at different deformations and isothermal temperatures on microstructuralstate of austen

  12. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    Science.gov (United States)

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles. PMID:25456348

  13. DSC analyses of static and dynamic precipitation of an Al–Mg–Si–Cu aluminum alloy

    OpenAIRE

    Manping Liu; Zhenjie Wu; Rui Yang; Jiangtao Wei; Yingda Yu; Pål C. Skaret; Hans J. Roven

    2015-01-01

    In the present investigation, both static and dynamic precipitations of an Al–Mg–Si–Cu aluminum alloy after solid-solution treatment (SST) were comparatively analyzed using differential scanning calorimetry (DSC). Dynamic aging was performed in the SST alloy through equal channel angular pressing (ECAP) at different temperatures of room temperature, 110, 170, 191 and 300 °C. For comparison, static artificial aging was conducted in the SST alloy at 191 °C with two aging times of 4 and 10 h. Th...

  14. Evidence for rapid epithermal mineralization and coeval bimodal volcanism, Bruner Au-Ag property, NV USA

    Science.gov (United States)

    Baldwin, Dylan

    The character of Au-Ag mineralization and volcanic/hydrothermal relationships at the underexplored Miocene-age Bruner low-sulfidation epithermal Au-Ag deposit are elucidated using field and laboratory studies. Bruner is located in central Nevada within the Great Basin extensional province, near several major volcanic trends (Western Andesite, Northern Nevada Rift) associated with world-class Miocene-age epithermal Au-Ag provinces. Despite its proximity to several >1 Moz Au deposits, and newly discovered high-grade drill intercepts (to 117 ppm Au/1.5m), there is no published research on the deposit, the style of mineralization has not been systematically characterized, and vectors to mineralization remain elusive. By investigating the nature of mineralization and time-space relationships between volcanic/hydrothermal activity, the deposit has been integrated into a regional framework, and exploration targeting improved. Mineralization occurs within narrow quartz + adularia +/- pyrite veins that manifest as sheeted/stockwork zones, vein swarms, and rare 0.3-2 m wide veins hosted by two generations of Miocene high-K, high-silica rhyolite flow dome complexes overlying an andesite flow unit. The most prominent structural controls on veining are N­striking faults and syn-mineral basalt/rhyolite dikes. Productive veins have robust boiling indicators (high adularia content, bladed quartz after calcite, recrystallized colloform quartz bands), lack rhythmic banding, and contain only 1-2 stages; these veins overprint, or occur separately from another population of barren to weakly mineralized rhythmically banded quartz-only veins. Ore minerals consist of coarse Au0.5Ag 0.5 electrum, fine Au0.7Ag0.3 electrum, acanthite, uytenbogaardtite (Ag3AuS2) and minor embolite Ag(Br,Cl). Now deeply oxidized, veins typically contain montmorillonite-chlorite (after biotite). The distribution of steam-heated alteration zones and vitrophyre units, along with prominent chemical and textural

  15. Optical and structural properties of Au-Ag islands films for plasmonic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sancho-Parramon, J.; Janicki, V.; Loncaric, M.; Zorc, H.; Dubcek, P. [Ruder Boskovic Institute, Zagreb (Croatia); Bernstorff, S. [Sincrotrone Trieste, Basovizza Trieste (Italy)

    2011-06-15

    Bimetallic islands films consisting of composite Au-Ag nanoparticles are deposited on glass substrates by electron beam evaporation. Broad tuning of the surface-plasmon resonance (SPR) characteristics can be achieved by controlling film composition, deposition temperature and post-deposition thermal annealing. Optical and structural characterization of the samples enable one to establish the link between the SPR and the morphological and compositional characteristics of nanoparticles. (orig.)

  16. New apparatus for DTA at 2000 bar: thermodynamic studies on Au, Ag, Al and HTSC oxides

    OpenAIRE

    Garnier, V.; Giannini, E.; Hugi, S.; Seeber, B.; Flukiger, R.

    2004-01-01

    A new DTA (Differential Thermal Analysis) device was designed and installed in a Hot Isostatic Pressure (HIP) furnace in order to perform high-pressure thermodynamic investigations up to 2 kbar and 1200C. Thermal analysis can be carried out in inert or oxidising atmosphere up to p(O2) = 400 bar. The calibration of the DTA apparatus under pressure was successfully performed using the melting temperature (Tm) of pure metals (Au, Ag and Al) as standard calibration references. The thermal propert...

  17. New isotopic evidence bearing on bonanza (Au-Ag) epithermal ore-forming processes

    Science.gov (United States)

    Saunders, James A.; Mathur, Ryan; Kamenov, George D.; Shimizu, Toru; Brueseke, Matthew E.

    2016-01-01

    New Cu, S, and Pb isotope data provide evidence for a magmatic source of metal(loid)s and sulfur in epithermal Au-Ag deposits even though their ore-forming solutions are composed primarily of heated meteoric (ground) waters. The apparent isotopic discrepancy between ore metals and ore-forming solutions, and even between the ore and associated gangue minerals, indicates two different sources of epithermal ore-forming constituents: (1) a shallow geothermal system that not only provides the bulk of water for the ore-forming solutions but also major chemical constituents leached from host rocks (silica, aluminum, potassium, sodium, calcium) to make gangue minerals and (2) metals and metalloids (As, Te, Sb, etc.) and sulfur (±Se) derived from deeper magma bodies. Isotopic data are consistent with either vapor-phase transport of metal(loids) and sulfur and their subsequent absorption by shallow geothermal waters or formation of metallic (Au, Ag, Cu phases) nanoparticles at depth from magmatic fluids prior to encountering the geothermal system. The latter is most consistent with ore textures that indicate physical transport and aggregation of nanoparticles were significant ore-forming processes. The recognition that epithermal Au-Ag ores form in tectonic settings that produce magmas capable of releasing metal-rich fluids necessary to form these deposits can refine exploration strategies that previously often have focused on locating fossil geothermal systems.

  18. Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays

    OpenAIRE

    Jing Liu; Yushan Chen; Haoyuan Cai; Xiaoyi Chen; Changwei Li; Cheng-Fu Yang

    2015-01-01

    In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA) numerical method as a function of refractive indexes of substrates and mediums. S...

  19. Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites

    Directory of Open Access Journals (Sweden)

    Pogacean F

    2014-02-01

    Full Text Available Florina Pogacean,1 Alexandru R Biris,2 Maria Coros,1 Mihaela Diana Lazar,1 Fumiya Watanabe,3 Ganesh K Kannarpady,3 Said A Farha Al Said,4 Alexandru S Biris,3 Stela Pruneanu1 1Department of Isotopic Physics and Technology, 2Department of Mass Spectrometry, Chromatography, and Applied Physics, National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania; 3Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, Little Rock, Arkansas, USA; 4Department of Physics, College of Science, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current

  20. Genetic Pd, Pt, Au, Ag, and Rh mineralogy in Noril'sk sulfide ores

    Science.gov (United States)

    Spiridonov, E. M.; Kulagov, E. A.; Serova, A. A.; Kulikova, I. M.; Korotaeva, N. N.; Sereda, E. V.; Tushentsova, I. N.; Belyakov, S. N.; Zhukov, N. N.

    2015-09-01

    The undeformed ore-bearing intrusions of the Noril'sk ore field (NOF) cut through volcanic rocks of the Late Permian-Early Triassic trap association folded in brachysynclines. Due to the nonuniform load on the roof of intrusive bodies, most sulfide melts were squeezed, up to the tops of ore-bearing intrusions; readily fusible Ni-Fe-Cu sulfide melts were almost completely squeezed. In our opinion, not only one but two stages of mineralization developed at the Noril'sk deposits: (i) syntrap magmatic and (ii) epigenetic post-trap metamorphic-hydrothermal. All platinum-group minerals (PGM) and minerals of gold are metasomatic in the Noril'sk ores. They replaced sulfide solid solutions and exsolution structures. All types of PGM and Au minerals occur in the ores, varying in composition from pyrrhotite to chalcopyrite, talnakhite, mooihoekite, and rich in galena; they are localized in the inner and outer contact zones and differ only in the quantitative proportions of ore minerals. The aureoles of PGM and Au-Ag minerals are wider than the contours of sulfide bodies and coincide with halos of fluid impact on orebodies and adjacent host rocks. The pneumatolytic PGM and Au-Ag minerals are correlated in abundance with the dimensions of sulfide bodies. Their amounts are maximal in veins of late fusible ore composed of eutectic PbS ss and iss intergrowths, as well as at their contacts. The Pd and Pt contents in eutectic sulfide ores of NOF are the world's highest. In the process of noble-metal mineral formation, the fluids supply Pd, Pt, Au, As, Sb, Sn, Bi, and a part of Te, whereas Fe, Ni, Cu, Pb, Ag, Rh, a part of Te and Pd are leached from the replaced sulfide minerals. The pneumatolytic PGM of the early stage comprises Pd and Pt intermetallic compounds enriched in Au along with Pd-Pt-Fe-Ni-Cu-Sn-Pb(As) and (Pd,Pt,Au)(Sn,Sb,Bi,Te,As) solid solutions. Pneumatolytic PGM and Au minerals of the middle stage are products of solid-phase transformation and recrystallization of

  1. Synthesis of biocompatible AuAgS/Ag2S nanoclusters and their applications in photocatalysis and mercury detection

    International Nuclear Information System (INIS)

    In this paper, a facile approach for preparation of AuAgS/Ag2S nanoclusters was developed. The unique AuAgS/Ag2S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag2S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag2S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg2+ and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag2S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.Graphical Abstract

  2. Synthesis of biocompatible AuAgS/Ag{sub 2}S nanoclusters and their applications in photocatalysis and mercury detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen, E-mail: hhwn09@163.com; Liu, Fengping [Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule, Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering (China); Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [Chinese Academy of Sciences, State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics (China)

    2014-12-15

    In this paper, a facile approach for preparation of AuAgS/Ag{sub 2}S nanoclusters was developed. The unique AuAgS/Ag{sub 2}S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag{sub 2}S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag{sub 2}S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg{sup 2+} and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag{sub 2}S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.Graphical Abstract.

  3. Synthesis of (Au)Ag core-shell nanocomposite in the water- ethanol mixture and its optical properties

    Science.gov (United States)

    Abakshonok, A. V.; Panarin, A. Yu; Agabekov, V. E.; Eryomin, A. N.; Terekhov, S. N.

    2014-08-01

    The technique of synthesis of (Au)Ag core-shell bimetallic nanocomposite was developed. Gold seed nanoparticles (NPs) were obtained by HAuCl4 reduction with sodium citrate at ultrasonic treatment during 3 hours in a mixture of water - ethanol (1:1). Then, the surface of gold NPs was modified by silver. In the presence of polyvinylpyrrolidone (PVP) K30 (Mw ~ 24000) and K90 (Mw ~ 360000) the coreshell (Au)Ag NPs of spherical shape were formed. They are characterized by aggregate stability and well-defined absorption maximum at 400-514 nm. Composite (Au)Ag, prepared in the solution without a polymer or in the presence of carboxymethylcellulose (CMC), sodium polystyrene sulfonate (PSS), dextran T100 and T500, had a broad band plasmon resonance in the whole range of visible spectrum. The ability to use the (Au)Ag core-shell nanoparticles in absorption nanospectroscopy based on the phenomenon of plasmon resonance energy transfer (PRET) was evaluated. In the presence of 0,1-2,0 μM of water-soluble cationic Cu (II) -5,10,15,20-tetrakis (4-N-methyl pyridinium) porphyrin (CuTMPyP4) distinct dips due to plasmon quenching matched the absorption maximum of CuTMPyP4 were detected in the resonant scattering spectrum of (Au)Ag solution.

  4. DSC analyses of static and dynamic precipitation of an Al–Mg–Si–Cu aluminum alloy

    Directory of Open Access Journals (Sweden)

    Manping Liu

    2015-04-01

    Full Text Available In the present investigation, both static and dynamic precipitations of an Al–Mg–Si–Cu aluminum alloy after solid-solution treatment (SST were comparatively analyzed using differential scanning calorimetry (DSC. Dynamic aging was performed in the SST alloy through equal channel angular pressing (ECAP at different temperatures of room temperature, 110, 170, 191 and 300 °C. For comparison, static artificial aging was conducted in the SST alloy at 191 °C with two aging times of 4 and 10 h. The DSC analyses reveal that the dynamic precipitation has occurred in the ECAPed samples, while the activation energies associated with the strengthening precipitates in the dynamic samples are considerably higher than the energies in the SST and static aged samples. The higher activation energies are probably attributed to the smaller grains and higher dislocation density developed after ECAP. The results in the present investigation allow the prediction of the type of the dynamic precipitates to influence the strength of the ultrafine grained alloy during ECAP at various temperatures.

  5. Electrodeposition of Au/Ag bimetallic dendrites assisted by Faradaic AC-electroosmosis flow

    Directory of Open Access Journals (Sweden)

    Jianlong Ji

    2014-03-01

    Full Text Available Au/Ag bimetallic dendrites were synthesized successfully from the corresponding aqueous solution via the AC electrodeposition method. Both of the morphologies and compositions could be tuned by the electrolyte concentration and AC frequency. The prepared bimetallic dendrites were characterized by scanning electron microscopy (SEM, energy dispersive X-ray spectrometer (EDS, transmission electron microscopy (TEM and UV–vis spectroscopy. The underlying dendrite growth mechanism was then proposed in the context of the Directed Electrochemical Nanowires Assembly (DENA models. Owing to the unscreened voltage dropping in the electrolyte bulk, electromigration dominates the species flux process, and cations tend to accumulate in areas with strong electric field intensity, such as electrode edges. Moreover, Faradaic AC-electro-osmosis (ACEO flow could increase the effective diffusion layer thickness in these areas during the electrochemical reaction, and leads to dendrite growth. Further Micro-Raman observations illustrated that the Au/Ag bimetallic dendrites exhibited pronounced surface-enhanced Raman scattering (SERS activity, using 4-mercaptopyridine (4-MP as model molecules.

  6. Rapid air film continuous casting of aluminum alloy using static magnetic field

    Institute of Scientific and Technical Information of China (English)

    Fu QU; Huixue JIANG; Gaosong WANG; Qingfeng ZHU; Xiangjie WANG; Jianzhong CUI

    2009-01-01

    The influences of the cooling style and static magnetic field on the air film casting process were investigated. Ingots of 6063 aluminum alloy were produced by AIRSOL VEIL casting with double-layer cooling water and static magnetic field. Surface segregation, hot crack and variation of solute content along the radius direction of ingot were examined. The results showed that double-layer cooling water can improve the surface quality and avoid of hot crack, which created conditions to increase the casting speed. The electromagnetic casting process can effectively improve the surface quality in high speed casting process, and static magnetic field has a great influence on solute distribution along the radius direction of ingot.

  7. Characterizing the economic value of an epithermal Au-Ag ore with Laser Induced Breakdown Spectroscopy (LIBS)

    NARCIS (Netherlands)

    Dalm, M.; Buxton, M.W.N.

    2016-01-01

    LIBS was applied to 19 Au-Ag ore samples to investigate if this technique can be used to distinguish between economic and sub-economic ore either by direct detection of these elements or by using other elements as indicators. However, the Au and Ag grades of the samples are below the detection limit

  8. Direct laser planting of hybrid Au-Ag/C nanostructures - nanoparticles, flakes and flowers

    CERN Document Server

    Manshina, Alina; Bashouti, Muhammad; Povolotskiy, Alexey; Petrov, Yuriy; Koshevoy, Igor; Christiansen, Silke; Tunik, Sergey; Leuchs, Gerd

    2015-01-01

    We demonstrate a new approach for forming hybrid metal/carbonaceous nanostructures in a controlled direct laser planting process. Au-Ag nanoclusters in amorphous or crystalline carbonaceous matrices are formed with different morphology: nanoparticles, nanoflakes, and nanoflowers. In contrast to other generation techniques our approach is simple, involving only a single laser-induced process transforming supramolecular complexes dissolved in solvent such as acetone, acetophenone, or dichloroethane into hybrid nanostructures in the laser-affected area of the substrate. The morphology of the hybrid nanostructures can be steered by controlling the deposition parameters, the composition of the liquid phase and the type of substrate, amorphous or crystalline. The carbonaceous phase of the hybrid nanostructures consists of hydrogenated amorphous carbon in the case of nanoparticles and of crystalline orthorhombic graphite of nanoscale thickness in the case of flakes and flowers. To the best of our knowledge this is t...

  9. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Zhang, Yayun; Zhong, Yanmei [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2015-08-30

    Graphical abstract: - Highlights: • A facile method was designed to synthesize Au@Ag@C core-double shell nanocomposites. • Carbon nanomaterials at the outermost layer could protect Au and Ag nanoparticles from oxidation and aggregation. • The Au@Ag@C core-double shell nanocomposites showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide. • The hydrogen peroxide sensor has a wide linear range of 5.0 μM to 4.75 mM and a limit of detection as low as 0.14 μM. - Abstract: The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H{sub 2}O{sub 2} according to the electrochemical experiments. It also demonstrates the H{sub 2}O{sub 2} sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H{sub 2}O{sub 2} sensor.

  10. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A facile method was designed to synthesize Au@Ag@C core-double shell nanocomposites. • Carbon nanomaterials at the outermost layer could protect Au and Ag nanoparticles from oxidation and aggregation. • The Au@Ag@C core-double shell nanocomposites showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide. • The hydrogen peroxide sensor has a wide linear range of 5.0 μM to 4.75 mM and a limit of detection as low as 0.14 μM. - Abstract: The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H2O2) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H2O2 according to the electrochemical experiments. It also demonstrates the H2O2 sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H2O2 sensor

  11. Facile synthesis and intraparticle self-catalytic oxidation of dextran-coated hollow Au-Ag nanoshell and its application for chemo-thermotherapy.

    Science.gov (United States)

    Jang, Hongje; Kim, Young-Kwan; Huh, Hyun; Min, Dal-Hee

    2014-01-28

    Galvanic replacement reaction is a useful method to prepare various hollow nanostructures. We developed fast and facile preparation of biocompatible and structurally robust hollow Au-Ag nanostructures by using dextran-coated Ag nanoparticles. Oxidation of the surface dextran alcohols was enabled by catalytic activity of the core Au-Ag nanostructure, introducing carbonyl groups that are useful for further bioconjugation. Subsequent doxorubicin (Dox) conjugation via Schiff base formation was achieved, giving high payload of approximately 35 000 Dox per particle. Near-infrared-mediated photothermal conversion showed high efficacy of the Dox-loaded Au-Ag nanoshell as a combinational chemo-thermotherapy to treat cancer cells. PMID:24383549

  12. DNA origami based Au-Ag-core-shell nanoparticle dimers with single-molecule SERS sensitivity

    Science.gov (United States)

    Prinz, J.; Heck, C.; Ellerik, L.; Merk, V.; Bald, I.

    2016-03-01

    DNA origami nanostructures are a versatile tool to arrange metal nanostructures and other chemical entities with nanometer precision. In this way gold nanoparticle dimers with defined distance can be constructed, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). We have optimized the size, composition and arrangement of Au/Ag nanoparticles to create intense SERS hot spots, with Raman enhancement up to 1010, which is sufficient to detect single molecules by Raman scattering. This is demonstrated using single dye molecules (TAMRA and Cy3) placed into the center of the nanoparticle dimers. In conjunction with the DNA origami nanostructures novel SERS substrates are created, which can in the future be applied to the SERS analysis of more complex biomolecular targets, whose position and conformation within the SERS hot spot can be precisely controlled.DNA origami nanostructures are a versatile tool to arrange metal nanostructures and other chemical entities with nanometer precision. In this way gold nanoparticle dimers with defined distance can be constructed, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). We have optimized the size, composition and arrangement of Au/Ag nanoparticles to create intense SERS hot spots, with Raman enhancement up to 1010, which is sufficient to detect single molecules by Raman scattering. This is demonstrated using single dye molecules (TAMRA and Cy3) placed into the center of the nanoparticle dimers. In conjunction with the DNA origami nanostructures novel SERS substrates are created, which can in the future be applied to the SERS analysis of more complex biomolecular targets, whose position and conformation within the SERS hot spot can be precisely controlled. Electronic supplementary information (ESI) available: Additional information about materials and methods, designs of DNA origami templates, height profiles, additional SERS spectra, assignment of DNA

  13. Chitosan-induced Au/Ag nanoalloy dispersed in IL and application in fabricating an ultrasensitive glucose biosensor based on luminol-H₂O₂-Cu²⁺/IL chemiluminescence system.

    Science.gov (United States)

    Chaichi, M J; Alijanpour, S O

    2014-11-01

    A novel glucose biosensor based on the chemiluminescence (CL) detection of enzymatically generated hydrogen peroxide (H₂O₂) was constructed by one covalent immobilization of glucose oxidase (GOD) in glutaraldehyde-functionalized glass cell. In following, chitosan-induced Au/Ag nanoparticles dispersed in ion liquid (IL) were synthesised and immobilized on it. Herein, chitosan molecules acted as both the reducing and stabilizing agent for the preparation of NPs and also, as a coupling agent GOD and Au/Ag alloy NPs. In addition to catalyze luminol CL reaction, these NPs offered excellent catalytic activity toward hydrogen peroxide generation in enzymatic reaction between GOD and glucose. The used IL in fabrication of biosensor increased its stability. Also, IL alongside Cu(2+) accelerated enzymatic and CL reaction kinetic, and decreased luminol CL reaction optimum pH to 7.5 which would enable sensitive and precision determination of glucose. Under optimum condition, linear response range of glucose was found to be 1.0 × 10(-6)-7.5 × 10(-3)M, and detection limit was 4.0 × 10(-7)M. The CL biosensor exhibited good storage stability, i.e., 90% of its initial response was retained after 2 months storage at pH 7.0. The present CL biosensor has been applied satisfactory to analysis of glucose in real serum and urine samples. PMID:25086323

  14. Core-shell Au/Ag nanoparticles embedded in silicate sol-gel network for sensor application towards hydrogen peroxide

    Indian Academy of Sciences (India)

    Shanmugam Manivannan; Ramasamy Ramaraj

    2009-09-01

    The electrocatalytic activity of core-shell Au100-Ag ( = 15, 27, 46, and 60) bimetallic nanoparticles embedded in methyl functionalized silicate MTMOS network towards the reduction of hydrogen peroxide was investigated by using cyclic voltammetry and chronoamperometric techniques. Core-shell Au/Ag bimetallic nanoparticles were characterized by absorption spectra and HRTEM. The MTMOS silicate sol-gel embedded Au73Ag27 core-shell nanoparticles modified electrode showed better synergistic electrocatalytic effect towards the reduction of hydrogen peroxide when compared to monometal MTMOS-Aunps and MTMOS-Agnps modified electrodes. These modified electrodes were studied without immobilizing any enzyme in the MTMOS sol-gel matrix. The present study highlights the influence of molar composition of Ag nanoparticles in the Au/Ag bimetallic composition towards the electrocatalytic reduction and sensing of hydrogen peroxide in comparison to monometal Au and Ag nanoparticles.

  15. Fluid inclusion chemistry of adularia-sericite epithermal Au-Ag deposits of the southern Hauraki Goldfield, New Zealand

    Science.gov (United States)

    Simpson, Mark P.; Strmic Palinkas, Sabina; Mauk, Jeffrey L.; Bodnar, Robert J.

    2015-01-01

    Microthermometry, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), and Raman spectroscopy have been used to determine the temperature, apparent salinity, and composition of individual fluid inclusions in adularia-sericite Au-Ag epithermal veins from the Karangahake, Martha, Favona, and Waitekauri deposits, southern Hauraki goldfield, New Zealand. Quartz veins contain colloform to crustiform bands that alternate with coarse-grained quartz and amethyst. The ore mineralization occurs only in colloform to crustiform bands.

  16. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    Science.gov (United States)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  17. Scanning surface-enhanced Raman spectroscopy (SERS) of chemical agent simulants on templated Au-Ag nanowire substrates

    Science.gov (United States)

    Hoffmann, J. A.; Miragliotta, J. A.; Wang, J.; Tyagi, P.; Maddanimath, T.; Gracias, D. H.; Papadakis, S. J.

    2009-05-01

    We report the results of scanning micro-Raman spectroscopy obtained on Au-Ag nanowires for a variety of chemical warfare agent simulants. Rough silver segments embedded in gold nanowires showed enhancement of 105 - 107 and allowed unique identification of 3 of 4 chemical agent simulants tested. These results suggest a promising method for detection of compounds significant for security applications, leading to sensors that are compact and selective.

  18. DNA-embedded Au-Ag core-shell nanoparticles assembled on silicon slides as a reliable SERS substrate.

    Science.gov (United States)

    Zhang, Zhong; Zhang, Sha; Lin, Mengshi

    2014-05-01

    This study aimed at developing a sensitive and reliable SERS substrate by assembling DNA-embedded Au-Ag core-shell nanoparticles (NPs) on silicon slides. First, a monolayer of well separated DNA-functionalized Au NPs (40 nm) was decorated on (3-aminopropyl)triethoxysilane modified silicon slides. The DNA-embedded Au-Ag core-shell NPs were assembled on the 40 nm Au-DNA NPs to form a core-satellite structure through DNA hybridization. Using 4-MBA as a Raman dye, the SERS performance of the substrates was evaluated after being cleaned by low oxygen and argon plasma. The Raman intensity of the assembly using DNA-embedded Au-Ag core-shell NPs was 8-10 times higher than the intensity of the assembly using Au NPs as satellites. In addition, the signal-to-noise ratio of the assembly was 2.6 times higher than that of a commercial substrate (Klarite™) when a 785 nm laser was used. The SERS enhancements of the assembled substrates were 2.2 to 2.8 times higher than the Klarite when an acquisition time of 5 s was used at an excitation wavelength of 633 nm. The assembled substrates also show a good spot-to-spot and substrate-to-substrate reproducibility at the excitation wavelengths of 633 and 785 nm. These results demonstrate that the fabrication process is simple and cost-effective for assembling DNA-embedded Au-Ag core-shell NPs on silicon slides that can be used as a reliable SERS substrate. PMID:24627887

  19. Electronic structure and conductivity of nanocomposite metal (Au,Ag,Cu,Mo)-containing amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, Jose L.; Horwat, David; Gago, Raul; Andersson, Joakim; Liu, Y.S.; Guo, Jinghua; Anders, Andre

    2008-05-14

    In this work, we study the influence of the incorporation of different metals (Me = Au, Ag, Cu, Mo) on the electronic structure of amorphous carbon (a-C:Me) films. The films were produced at room temperature using a novel pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas X-ray diffraction was used to identify the formation of metal nanoclusters in the carbon matrix. The metal content incorporated in the nanocomposite films induces a drastic increase in the conductivity, in parallel with a decrease in the band gap corrected from Urbach energy. The electronic structure as a function of the Me content has been monitored by x-ray absorption near edge structure (XANES) at the C K-edge. XANES showed that the C host matrix has a dominant graphitic character and that it is not affected significantly by the incorporation of metal impurities, except for the case of Mo, where the modifications in the lineshape spectra indicated the formation of a carbide phase. Subtle modifications of the spectral lineshape are discussed in terms of nanocomposite formation.

  20. Assemblies of silicate sol-gel matrix encapsulated core/shell Au/Ag nanoparticles: interparticles surface plasmon coupling

    Energy Technology Data Exchange (ETDEWEB)

    Manivannan, Shanmugam; Ramaraj, Ramasamy, E-mail: ramarajr@yahoo.com [Madurai Kamaraj University, Centre for Photoelectrochemistry, School of Chemistry (India)

    2012-06-15

    Cluster-like assemblies of bimetal core/shell Au/Ag nanoparticles were prepared. The Ag shell was deposited on the preformed Au nanoparticles using two different types of preformed Au nanoparticles in the presence of EDAS silane monomer, one stabilized by citrate and other by {beta}-cyclodextrin. The Ag shell was deposited on the preformed Au nanoparticles by the reduction of Ag{sup +} ions by {beta}-cyclodextrin and EDAS silane composite. Interestingly, productive Ag shell deposition occurred only on the {beta}-cyclodextrin-stabilized Au nanoparticles and led to the assembly formation, whereas aggregation occurred with the citrate-stabilized Au nanoparticles. The average particle size of the core/shell Au/Ag nanoparticles was found to be 6.5 nm. Spectral features of this assembly of core/shell Au/Ag nanoparticles resembled the longitudinal surface plasmon resonance behavior of Au nanorod-like structures arising from the interparticles surface plasmon coupling. The assemblies so prepared were characterized by uv-vis absorption spectroscopy and high-resolution transmission electron microscopy.Graphical Abstract.

  1. Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2015-05-01

    Full Text Available In this study, the nanosphere lithography (NSL method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz and 1.68 (SF5 glass, the nanoparticle arrays would have better refractive index sensitivity (RIS and figure of merit (FOM. Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results.

  2. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    Science.gov (United States)

    Li, Yancai; Zhang, Yayun; Zhong, Yanmei; Li, Shunxing

    2015-08-01

    The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H2O2) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H2O2 according to the electrochemical experiments. It also demonstrates the H2O2 sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H2O2 sensor.

  3. Bio-mimetic Nanostructure Self-assembled from Au@Ag Heterogeneous Nanorods and Phage Fusion Proteins for Targeted Tumor Optical Detection and Photothermal Therapy

    OpenAIRE

    Fei Wang; Pei Liu; Lin Sun; Cuncheng Li; Valery. A. Petrenko; Aihua Liu

    2014-01-01

    Nanomaterials with near-infrared (NIR) absorption have been widely studied in cancer detection and photothermal therapy (PTT), while it remains a great challenge in targeting tumor efficiently with minimal side effects. Herein we report a novel multifunctional phage-mimetic nanostructure, which was prepared by layer-by-layer self-assembly of Au@Ag heterogenous nanorods (NRs) with rhodamine 6G, and specific pVIII fusion proteins. Au@Ag NRs, first being applied for PTT, exhibited excellent stab...

  4. Tailor-made Au-Ag core–shell nanoparticle 2D arrays on protein-coated graphene oxide with assembly enhanced antibacterial activity

    International Nuclear Information System (INIS)

    Water-dispersible two-dimensional (2D) assemblies of Au-Ag core–shell nanoparticles are obtained through a highly selective electroless silver deposition on pre-assembled gold nanoparticles on bovine serum albumin (BSA)-coated graphene oxide (BSA-GO). While neither BSA-GO nor AuNP-decorated BSA-GO shows any antibacterial ability, the silver-coated GO-Au nanosheets (namely GO-Au-Ag) exhibit an enhanced antibacterial activity against Gram-negative Escherichia coli (E. coli) bacteria, superior to unassembled Au-Ag nanoparticles and even ionic Ag. Such an improvement may be attributed to the increased local concentration of silver nanoparticles around a bacterium and a polyvalent interaction with the bacterial surface. In addition, the colloidal stability of this novel nano-antimicrobial against the formation of random nanoparticle aggregates guarantees a minimized activity loss of the Au-Ag nanoparticles. The antibacterial efficacy of GO-Au-Ag is less sensitive to the existence of Cl−, in comparison with silver ions, providing another advantage for wound dressing applications. Our research unambiguously reveals a strong and very specific interaction between the GO-Au-Ag nanoassembly and E. coli, which could be an important clue toward a rational design, synthesis and assembly of innovative and highly active antibacterial nanomaterials. (paper)

  5. Effect of hot-humid exposure on static strength of adhesive-bonded aluminum alloys

    Directory of Open Access Journals (Sweden)

    Rui Zheng

    2015-09-01

    Full Text Available The effect of hot-humid exposure (i.e., 40 °C and 98% R.H. on the quasi-static strength of the adhesive-bonded aluminum alloys was studied. Test results show that the hot-humid exposure leads to the significant decrease in the joint strength and the change of the failure mode from a mixed cohesive and adhesive failure with cohesive failure being dominant to adhesive failure being dominant. Careful analyses of the results reveal that the physical bond is likely responsible for the bond adhesion between L adhesive and aluminum substrates. The reduction in joint strength and the change of the failure mode resulted from the degradation in bond adhesion, which was primarily attributed to the corrosion of aluminum substrate. In addition, the elevated temperature exposure significantly accelerated the corrosion reaction of aluminum, which accelerated the degradation in joint strength.

  6. Static rock splitters based on high temperature shape memory alloys for planetary explorations

    Science.gov (United States)

    Benafan, O.; Noebe, R. D.; Halsmer, T. J.

    2016-01-01

    A static rock splitter device based on high-force, high-temperature shape memory alloys (HTSMAs) was developed for space related applications requiring controlled geologic excavation in planetary bodies such as the moon, Mars, and near-Earth asteroids. The device, hereafter referred to as the shape memory alloy rock splitter (SMARS), consisted of active (expanding) elements made of Ni50.3Ti29.7Hf20 (at%) that generate extremely large forces in response to thermal input. The pre-shaping (training) of these elements was accomplished using isothermal, isobaric and cyclic training methods, which resulted in active components capable of generating stresses in excess of 1.5 GPa. The corresponding strains (or displacements) were also evaluated and were found to be 2-3%, essential to rock fracturing and/or splitting when placed in a borehole. SMARS performance was evaluated using a testbed consisting of a temperature controller, custom heaters and heater holders, and an enclosure for rock placement and breakage. The SMARS system was evaluated using various rock types including igneous rocks (e.g., basalt, quartz, granite) and sedimentary rocks (e.g., sandstone, limestone).

  7. Static and Vibrational Properties of Equiatomic Cesium-Alkali Binary Alloys

    Directory of Open Access Journals (Sweden)

    Aditya M. Vora

    2012-07-01

    Full Text Available The computations of the static and vibrational properties of four equiatomic Cs-based binary alloys viz. Cs0.5Li0.5, Cs0.5Na0.5, Cs0.5K0.5 and Cs0.5Rb0.5 to second order in local model potential is discussed in terms of real-space sum of Born von Karman central force constants. The local field correlation functions due to Hartree (H, Ichimaru-Utsumi (IU and Sarkar et al. (S are used to investigate influence of the screening effects on the aforesaid properties. Results for the lattice constants, i.e. С11, С12, С44, С12 – С44, С12 / С44, and bulk modulus B obtained using the H-local field correction function, have higher values in comparison with the results obtained for the same properties using IU and S local field correction functions. The results for the Shear modulus (C, deviation from Cauchy’s relation, Poisson’s ratio , Young modulus Y, propagation velocity of elastic waves, phonon dispersion curves and degree of anisotropy A are highly appreciable for the four equiatomic Cs-based binary alloys.

  8. Sonochemically synthesized mono and bimetallic Au-Ag reduced graphene oxide based nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Neppolian, Bernaurdshaw; Wang, Chang; Ashokkumar, Muthupandian

    2014-11-01

    Graphene oxide (GO) supported Ag and Au mono-metallic and Au-Ag bimetallic catalysts were synthesized using a sonochemical method. Bimetallic catalysts containing different weight ratios of Au and Ag were loaded onto GO utilizing a low frequency horn-type ultrasonicator. High frequency ultrasonication was used to efficiently reduce Ag(I) and Au(III) ions in the presence of polyethylene glycol and 2-propanol. Transmission electron microscopy (TEM-EDX) and X-ray photoelectron spectroscopy were used to analyze the morphology, size, shape and chemical oxidation states of the prepared metallic catalysts on GO. The catalytic efficiency of the prepared catalysts were compared using 4-nitrophenol (4-NP) reduction reaction and the subsequent formation of 4-aminophenol (4-AP) that was also monitored using UV-vis spectrophotometry. The results revealed that Au-Ag-GO bimetallic catalysts showed high activity for the conversion of 4-NP to 4-AP than their monometallic counterparts. Amongst different weight ratios (1:1, 1:2 and 2:1) between Au and Ag, the 1:2 (Au:Ag) catalyst exhibited very good catalytic performance for the conversion of 4-NP to 4-AP. A total reduction of 4-NP took place within a short period of time if Au-GO was reduced first followed by Ag reduction, whereas a lower reduction rate was observed if Ag-GO was reduced first. The same trend was observed for all the ratios of bimetallic catalysts prepared by this method. The initial unfavorable reduction potential of Ag(I) is likely to be responsible for the above order. It was found that applying dual frequency ultrasonication was a highly effective way of preparing bimetallic catalysts requiring relatively low levels of added chemicals and producing bimetallic catalysts with GO with improved catalytic efficiency. PMID:24582660

  9. Structural control and K/Ar dating of the Au-Ag epithermal veins in the Shila Cordillera, southern Peru

    International Nuclear Information System (INIS)

    The Au-Ag epithermal mineralization of the Shila Cordillera is dated at about 10.7 Ma (K/Ar on adularia). The vein system is characterized by the association of a major ≅ east-west vein and N120-135 deg. E secondary fractures. The strike-slip faults controlling the veins indicate an initial NE-SW to ENE-WSW Shortening direction, which is compatible with that generally accepted for this period. These structures were reopened during a second phase and channeled mineralizing fluids, the circulation of which may have began at the end of stage 1. (authors)

  10. Compatibility of 31 metals, alloys and coatings with static Pb-17Li eutectic mixture

    International Nuclear Information System (INIS)

    The compatibility of 31 metals, alloys and coatings with static eutectic mixture Pb-17Li was investigated in more than 300 tests. Most of the results have not been published before. Wetting has no influence on dissolution rates. This is discussed in detail. Metals can be divided into three groups. Most stable are the refractories Nb, Ta, Mo, Re and W. Ferritic steels, Be, Fe, and V belong to the next group. However, Be is destroyed along grain boundaries. Not stable at all are Al, Ti, Zr, Y, U and their alloys. Temperature functions for solubilities in Pb-17Li were obtained for 8 elements, single -one temperature- values for 3 others. The results are in good agreement with a theoretical work of Guminski. Remarkably high are solubilities of Al, Zr, Y and U while those of the refractories are low. Also, the solubility of Pb in solid Ti was determined, adding new data points to the phase diagram. Because of the effect of mass transfer between dissimilar metals, diffusion coefficients in Pb-17Li could be calculated from dissolution rates and solubilities. Most reliable are the temperature functions for Be, Al, Fe and V. Those for Ti, Zr and U are influenced by the formation of compounds. All values are in an expected range, but not all effects can be explained. Different kinds of reaction zones were found on surfaces. New is a very thin ''chemical reaction zone'', identified for several metals during sample cleaning. It is probably formed as a first step before grain boundary attack of the eutectic. (orig.)

  11. Quantitative detection of uric acid by electrochemical-surface enhanced Raman spectroscopy using a multilayered Au/Ag substrate.

    Science.gov (United States)

    Zhao, Lili; Blackburn, Jonathan; Brosseau, Christa L

    2015-01-01

    Uric acid is a potential important biomarker in urine and serum samples for early diagnosis of preeclampsia, a life-threatening hypertensive disorder that occurs during pregnancy. Preeclampsia is a leading cause of maternal death, especially in developing nation settings. Quantitative detection of uric acid for rapid and routine diagnosis of early preeclampsia using electrochemical-surface enhanced Raman spectroscopy (EC-SERS) is presented herein. A uniform EC-SERS active Au/Ag substrate was developed by depositing nearly monodisperse gold and silver nanoparticles on the carbon working electrode surface of screen printed electrodes. The multilayered Au/Ag substrates were characterized by electron microscopy and used for quantitative detection of uric acid in 0.1 M NaF and synthetic urine at clinically relevant concentrations. These results showed a linear relationship between the EC-SERS signal intensity and the uric acid concentration. Relative errors calculated for selected concentrations were all within the Clinical Laboratory Improvement Amendments (CLIA) criterion for uric acid analysis (±17%). It is believed that routine and early diagnosis of disease could be possible through such quantitative detection of biomarkers in patient samples using this EC-SERS method. PMID:25483146

  12. Phase formation study of noble metal (Au, Ag and Pd) doped lanthanum perovskites synthesized by hydrothermal method

    International Nuclear Information System (INIS)

    Noble metal (Au, Ag and Pd) doped Lanthanum perovskites (LaMnO3, LaCrO3 and LaFeO3) have been synthesized by hydrothermal method. The effect of dopant and their concentration on the phase purity, crystallite size, morphology and magnetic character of the synthesized perovskites were systematically studied by FTIR spectroscopy, XRD, TGA, SEM, ICP-AES and VSM. The results show that phase pure products were obtained only after calcining the hydrothermally synthesized products above 760 °C for a minimum of 6 h. Nature and concentration of the dopant plays an important role in determining the phase formation temperature, morphology and magnetic character. The dopant ion preferentially occupies A-site and homogeneous phase of product is obtained upto a dopant concentration of 4%, higher concentration results in phase separation. The products exhibit spherical morphology. Lanthanum ferrite shows ferromagnetic nature, while the doped samples show weak magnetic properties. - Highlights: • Hydrothermal synthesis of noble metal doped lanthanum perovskites. • Site preference of noble metal (Au, Ag and Pd) doping in LaBO3 (B = Mn, Cr and Fe). • Dopant ions affect the phase formation temperature and morphology the perovskites. • 4% appears to be the maximum limit of doping at A-site

  13. Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xiu, Fu-Rong, E-mail: xiu_chem@hotmail.com [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Qi, Yingying [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Zhang, Fu-Shen [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2015-07-15

    Highlights: • We report a novel process for recovering Au, Ag, and Pd from waste PCBs. • The effect of SCWO on the leaching of Au, Ag, and Pd in waste PCBs was studied. • SCWO was highly efficient for enhancing the leaching of Au, Ag, and Pd. • The optimum leaching parameters for Au, Ag, and Pd in iodine–iodide were studied. - Abstract: Precious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine–iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercritical water, then a diluted hydrochloric acid leaching (HL) process was used to recovery the Cu, whose leaching efficiency was approximately 100%, finally the resulting residue was subjected to the iodine–iodide leaching process for recovering the Au, Ag, and Pd. Experimental results indicated that SCWO pre-treatment temperature, time, and pressure had significant influence on the Au, Ag, and Pd leaching from (SCWO + HL)-treated waste PCBs. The optimal SCWO pre-treatment conditions were 420 °C and 60 min for Au and Pd, and 410 °C and 30 min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO + HL)-treated PCBs with iodine–iodide system were leaching time of 120 min (90 min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10 g/mL (1:8 g/mL for Ag), and pH of 9, respectively. It is believed that the process developed in this study is environment friendly for the recovery of Au, Ag, and Pd from waste PCBs of mobile phones by SCWO pre-treatment combined with iodine–iodide leaching process.

  14. Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

    International Nuclear Information System (INIS)

    Highlights: • We report a novel process for recovering Au, Ag, and Pd from waste PCBs. • The effect of SCWO on the leaching of Au, Ag, and Pd in waste PCBs was studied. • SCWO was highly efficient for enhancing the leaching of Au, Ag, and Pd. • The optimum leaching parameters for Au, Ag, and Pd in iodine–iodide were studied. - Abstract: Precious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine–iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercritical water, then a diluted hydrochloric acid leaching (HL) process was used to recovery the Cu, whose leaching efficiency was approximately 100%, finally the resulting residue was subjected to the iodine–iodide leaching process for recovering the Au, Ag, and Pd. Experimental results indicated that SCWO pre-treatment temperature, time, and pressure had significant influence on the Au, Ag, and Pd leaching from (SCWO + HL)-treated waste PCBs. The optimal SCWO pre-treatment conditions were 420 °C and 60 min for Au and Pd, and 410 °C and 30 min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO + HL)-treated PCBs with iodine–iodide system were leaching time of 120 min (90 min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10 g/mL (1:8 g/mL for Ag), and pH of 9, respectively. It is believed that the process developed in this study is environment friendly for the recovery of Au, Ag, and Pd from waste PCBs of mobile phones by SCWO pre-treatment combined with iodine–iodide leaching process

  15. Gold-silver-alloy nanoprobes for one-pot multiplex DNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Doria, G; Larguinho, M; Dias, J T; Baptista, P V [Centro de Investigacao em Genetica Molecular Humana (CIGMH), Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Pereira, E [Rede de Quimica e Tecnologia (REQUIMTE), Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, 4169-007 Porto (Portugal); Franco, R, E-mail: pmvb@fct.unl.pt [Rede de Quimica e Tecnologia (REQUIMTE), Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2010-06-25

    A specific colorimetric DNA detection method based on oligonucleotide functionalized gold-silver-alloy nanoparticles (AuAg-alloy-nanoprobes) is presented. The AuAg-alloy-nanoprobes were then used for the specific detection of a DNA sequence from TP53-a gene involved in cancer development. The AuAg-alloy-nanoprobes were then used in combination with Au-nanoprobes for a one-pot dual-colour detection strategy that allowed for the simultaneous differential detection of two distinct target sequences. This system poses an unprecedented opportunity to explore the combined use of metal nanoparticles with different composition towards the development of a multiplex one-pot colorimetric assay for DNA detection.

  16. Simulation of the texture evolution of aluminum alloys during primary static recrystallization using a cellular automaton approach

    Energy Technology Data Exchange (ETDEWEB)

    Marx, V.; Gottstein, G. [RWTH Aachen (Germany). Inst. fuer Metallkunde und Metallphysik

    1998-12-31

    A 3D model has been developed to simulate both primary static recrystallization and recovery of cold worked aluminum alloys. The model is based on a modified cellular automaton approach and incorporates the influence of crystallographic texture and microstructure in respect to both mechanisms mentioned above. The model takes into account oriented nucleation using an approach developed by Nes for aluminum alloys. The subsequent growth of the nuclei depends on the local stored energy of the deformed matrix (i.e. the driving pressure) and the misorientation between a growing nucleus and its surrounding matrix (i.e. the grain boundary mobility). This approach allows to model preferred growth of grains that exhibit maximum growth rate orientation relationship, e.g. for aluminum alloys a 40{degree}<111> relationship with the surrounding matrix. The model simulates kinetics, microstructure and texture development during heat treatment, discrete in time and space.

  17. Comparative study of the microstructure of 5052 aluminum alloy sheets under quasi-static and high-velocity tension

    International Nuclear Information System (INIS)

    Highlights: ► Dislocation slip mechanism works during both quasi-static and dynamic deformation. ► Dynamic deformation induces denser dislocations and more cross-slip tendency. ► Existed prestrain has an accommodating effect on dislocation generation and motion. - Abstract: In order to reveal the high-velocity deformation mechanisms of 5052 aluminum alloy sheets, this work compares the dynamic plastic deformation behavior and the microstructure evolutions with those of the quasi-static case by scanning electron microscopy (SEM) observations, electron back scattering diffraction (EBSD) analysis, and transmission electron microscopy (TEM) studies. Results show that the dynamic process exhibits a very different macro fracture shape and a much similar micro deformation pattern as compared with the quasi-static case, and under both conditions, the dislocation-slip mechanism works during deformation. For the shock effect of high-velocity deformation, much denser dislocations are generated and the tendency of cross-slip of dislocations increases. The dislocation bands are more narrow and denser than those shown in the quasi-static case, and a much more uniform dislocation configuration is also exhibited after dynamic loadings. In addition, under dynamic conditions, the existing of pre-strain will introduce an accommodated effect on the dynamically induced dislocations, a slight reduction of density combining with a higher movement tendency. The characteristics of multi-slips and homogenization effect of dislocations under dynamic conditions will result in much higher plasticity and strength of materials over the quasi-static ones.

  18. Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core-shell nanoparticles

    Science.gov (United States)

    Kang, Fei; Hou, Xiangshu; Xu, Kun

    2015-10-01

    Glucose is a key energy substance in diverse biology and closely related to the life activities of the organism. To develop a simple and sensitive method for glucose detection is extremely urgent but still remains a key challenge. Herein, we report a colorimetric glucose sensor in a homogeneous system based on DNA-embedded core-shell Au@Ag nanoparticles. In this assay, a glucose substrate was first catalytically oxidized by glucose oxidase to produce H2O2 which would further oxidize and gradually etch the outer silver shell of Au@Ag nanoparticles. Afterwards, the solution color changed from yellow to red and the surface plasmon resonance (SPR) band of Au@Ag nanoparticles declined and red-shifted from 430 to 516 nm. Compared with previous silver-based glucose colorimetric detection strategies, the distinctive SPR band change is superior to the color variation, which is critical to the high sensitivity of this assay. Benefiting from the outstanding optical property, robust stability and well-dispersion of the core-shell Au@AgNPs hybrid, this colorimetric assay obtained a detection limit of glucose as low as 10 nM, which is at least a 10-fold improvement over other AgNPs-based procedures. Moreover, this optical biosensor was successfully employed to the determination of glucose in fetal bovine serum.

  19. Applicability of near-infrared hyperspectral imagery (NIR-HI) for sensor based sorting of an epithermal Au-Ag ore

    NARCIS (Netherlands)

    Dalm, M.; Buxton, M.W.N.; Van Ruitenbeek, F.J.A.

    2015-01-01

    In the presented study test work was performed with near-infrared hyperspectral imagery (NIR-HI) on 36 ore samples from a South-American epithermal Au-Ag mine. The aim of the test work was to investigate if NIR-HI provides information about the alteration mineralogy of samples that can be used to pr

  20. Rapidity density distributions in Au+Au and Au+Ag interactions at 11.6 A GeV/c

    International Nuclear Information System (INIS)

    Pseudorapidity density distributions of charged particles in heavy-ion collisions have been studied. The results from EMU01 have been compared to the results from the experiments WA80 and E802. The recently obtained pseudorapidity distributions from Au+Au and Au+Ag interactions have been compared to a linear extrapolation from lighter systems. (orig.)

  1. Tunable Catalysis of Water to Peroxide with Anionic, Cationic, and Neutral Atomic Au, Ag, Pd, Rh, and Os

    CERN Document Server

    Suggs, Kelvin; Tesfamichael, Aaron; Felfli, Zineb; Msezane, Alfred Z

    2014-01-01

    Fundamental anionic, cat-ionic, and neutral atomic metal predictions utilizing density functional theory calculations validate the recent discovery identifying the interplay between the resonances and the RT minimum obtained through complex angular momentum analysis as the fundamental atomic mechanism underlying nano-scale catalysis. Here we investigate the optimization of the catalytic behavior of Au, Ag, Pd, Rh, and Os atomic systems via polarization effects and conclude that anionic atomic systems are optimal and therefore ideal for catalyzing the oxidation of water to peroxide, with anionic Os being the best candidate. The discovery that cat-ionic systems increase the transition energy barrier in the synthesis of peroxide could be important as inhibitors in controlling and regulating catalysis. These findings usher in a fundamental and comprehensive atomic theoretical framework for the generation of tun-able catalytic systems.

  2. Crystal Chemistry of Natural Tellurides. I: Refinement of the Crystal Structure of Sylvanite, AuAgTe4

    International Nuclear Information System (INIS)

    Electron microprobe analyses and the refinement of the crystal structure indicate, that sylvanite, AuAgTe4, from Baia de Aries (=Offenbanya), Romania, has a stoichiometric composition and an ordered crystal structure (a-8.95(1) A, b=4.478(5) A, c=14.62(2) A; β=145.35(5)supo; Z-2; space group P2/c-Csub(2h)4). The Au atom is surrounded by six Te atoms in a [4+2] coordination as characteristic for oxidation state III. Around the Ag atom (oxidation state I) are also six Te atoms, but arranged in a [2+2+2] coordination. Via common edges the AuTe6 and AgTe6 polyhedra build up 'sheets' parallel to (100). These 'sheets' are combined to a network of Te2 dumbbells (Te-Te=2.82 A). (Author)

  3. Corrosion of Cr bearing low alloy pipeline steel in CO2 environment at static and flowing conditions

    International Nuclear Information System (INIS)

    We study the corrosion performance of Cr bearing low alloy pipeline steel (Cr3MoNi) in CO2 saturated formation water, under both static and flowing conditions. Cross-sectional morphologies of corrosion scales at progressively increased test duration are observed by scanning electron microscopy. The characteristic of the corrosion scales are investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. Our results show that the corrosion rate of Cr3MoNi steel at flowing condition is higher than that of static condition, and the degree of Cr enrichment in the scales at flowing condition is also higher. Flow also makes ions distribute evenly in the solution close to the specimen, leading to a uniform distribution of Cr compound in the amorphous corrosion scales. In this way, flow suppresses the presence of the potential pits and also leads to a more flat scale/substrate interface.

  4. Texture Evaluation of a Bi-Modal Structure During Static Recrystallization of Hot-Deformed Mg-Al-Sn Alloy

    Science.gov (United States)

    Kabir, Abu Syed Humaun; Su, Jing; Yue, Stephen

    2016-02-01

    In this study, Mg-Al-Sn alloy was hot compressed at 523 K (250 °C) and annealed at 623 K (350 °C) for various times. The initial as-deformed microstructure was partially dynamic recrystallized with strain-induced precipitates on the recrystallized grain boundaries. After annealing at 623 K (350 °C), static recrystallization (SRX) of the bimodal microstructure took place where, at this temperature, no static precipitates formed. The goal of this work was to study the effect of dynamic precipitation on the texture evolution during the SRX process. Progressive texture evolution was studied during annealing by electron backscattered diffraction technique through a microstructure-tracking process. It was found that the grain-coarsening mechanism during the early stage of annealing is not totally controlled by the basal-oriented grains. Also, it was found that the dynamic precipitates may have significant influence in the early texture weakening during annealing of a bimodal structure.

  5. The combined effect of static recrystallization and twinning on texture in magnesium alloys AM30 and AZ31

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Etienne; Jiang, Lan; Jonas, John J. [McGill Univ., Montreal, Quebec (Canada). Dept. of Materials Engineering; Godet, Stephane [Univ. Libre de Bruxelles (Belgium). Service Matieres et Materiaux

    2009-04-15

    The potential for decreasing the texture intensity generated during the bulk deformation of Mg alloys was investigated using a combination of contraction twinning, double (secondary) twinning and static recrystallization. A large number of twins was induced by tensile deformation at room temperature. Their volume fraction and the variants selected during straining were found to be largely responsible for the changes evident in the deformation texture. Recrystallization of the twins generated a fine-grained microstructure, although no growth into the matrix grains was observed. In this way, annealing of the deformed samples did not lead to significant further texture changes. (orig.)

  6. Effect of Ultrasonic Treatment in the Static and Dynamic Mechanical Behavior of AZ91D Mg Alloy

    Directory of Open Access Journals (Sweden)

    Helder Puga

    2015-11-01

    Full Text Available The present study evaluates the effect of high-intensity ultrasound (US in the static and dynamic mechanical behavior of AZ91D by microstructural modification. The characterization of samples revealed that US treatment promoted the refinement of dendrite cell size, reduced the thickness, and changed the β-Mg17Al12 intermetallic phase to a globular shape, promoted its uniform distribution along the grain boundaries and reduced the level of porosity. In addition to microstructure refinement, US treatment improved the alloy mechanical properties, namely the ultimate tensile strength (40.7% and extension (150% by comparison with values obtained for castings produced without US vibration. Moreover, it is suggested that the internal friction, enhanced by the reduction of grain size, is compensated by the homogenization of the secondary phase and reduction of porosity. It seems that by the use of US treatment, it is possible to enhance static mechanical properties without compromising the damping properties in AZ91D alloys.

  7. Influence of silver on the glycerol electro-oxidation over AuAg/C catalysts in alkaline medium: a cyclic voltammetry and in situ FTIR spectroscopy study

    International Nuclear Information System (INIS)

    In the present work, we investigated the influence of silver on the glycerol electro-oxidation over carbon-supported AuAg catalysts by cyclic voltammetry and in situ FTIR spectroscopy. We observed that the presence of Ag in the bimetallic materials provided a more efficient catalyst in terms of the ability to electro-oxidize glycerol at relatively low potentials. On the other hand, the bimetallic catalysts were found to be less promising than the Au/C catalyst with respect to the reaction rate. Ag addition influenced the mechanism of glycerol electro-oxidation, favoring the C-C-C bond breaking, as evidenced by the selective formation of formic acid on the bimetallic catalysts. The impact of Ag on the glycerol electro-oxidation over AuAg/C may be driven by electronic modifications and Ag segregation on the catalysts surface

  8. Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

    Science.gov (United States)

    Zhang, Yong; Shoaib, Anwer; Li, Jiaojiao; Ji, Muwei; Liu, Jiajia; Xu, Meng; Tong, Bin; Zhang, Jiatao; Wei, Qin

    2016-05-15

    Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis. PMID:26785311

  9. Comparative efficiencies of photothermal destruction of malignant cells using antibody-coated silica@Au nanoshells, hollow Au/Ag nanospheres and Au nanorods

    Science.gov (United States)

    Cheng, Fong-Yu; Chen, Chen-Tai; Yeh, Chen-Sheng

    2009-10-01

    Three Au-based nanomaterials (silica@Au nanoshells, hollow Au/Ag nanospheres and Au nanorods) were evaluated for their comparative photothermal efficiencies at killing three types of malignant cells (A549 lung cancer cells, HeLa cervix cancer cells and TCC bladder cancer cells) using a CW NIR laser. Photodestructive efficiency was evaluated as a function of the number of nanoparticles required to destroy the cancer cells under 808 nm laser wavelength at fixed laser power. Of the three nanomaterials, silica@Au nanoshells needed the minimum number of particles to produce effective photodestruction, whereas Au nanorods needed the largest number of particles. Together with the calculated photothermal conversion efficiency, the photothermal efficiency rankings are silica@Au nanoshells > hollow Au/Ag nanospheres > Au nanorods. Additionally, we found that HeLa cells seem to present better heat tolerance than the other two cancer cell lines.

  10. Optimized core-shell Au@Ag nanoparticles for label-free Raman determination of trace Rhodamine B with cancer risk in food product.

    Science.gov (United States)

    Wang, Hui; Guo, Xiaoyu; Fu, Shuyue; Yang, Tianxi; Wen, Ying; Yang, Haifeng

    2015-12-01

    A simple and reliable method based on surface-enhanced Raman scattering (SERS) with a portable Raman system is described for sensitive determination of trace levels of Rhodamine B (RB) in hot sauce samples. The sodium salt of phytic acid (IP6) stabilized Au@Ag core-shell bimetallic nanoparticles are constructed and used as SERS substrate, yielding high Raman enhancement of RB. The limit of detection for RB in water is 5 nM (2 ppb), which is below China Exit and Entry Inspection and Quarantine Bureau's tolerance level of 5 ppb. Also, the proposed easy assay of IP6-Au@Ag NPs combining with portable Raman system could be applied for on-site monitoring RB in hot sauce. PMID:26041175

  11. Aligned Solidification Structure of the MnBi Phase in Semisolidified Bi-Mn Alloy with a Static Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    Zhongming REN; Hui WANG; Kang DENG; Kuangdi XU

    2004-01-01

    The solidification structure of Bi-3 wt pct Mn alloy grown up in the semisolid zone under the influence of a static magnetic field (up to 1.0 T) and the relation of the magnetic property with the solidification structure have been investigated experimentally. It was shown that the primary phase MnBi crystals in the alloy aligned and oriented along the direction of the applied magnetic field. The orientating tendency and the average length of the elongated MnBi crystals increased with the increase of the applied field and the solidification time. Moreover, the remanence of the alloy along the aligned direction of the MnBi phase in the case of solidification with a magnetic field was apparently anisotropic and nearly double of that without the magnetic field. This indicated that the MnBi crystals oriented and aligned along their easy magnetization axis. A model was proposed to explain the alignment and orientation growth of the MnBi crystals in a magnetic field in terms of the magnetic anisotropy of the crystals and the magnetic interaction between them.

  12. Using Geomodelling and Geophysical Inversion to Evaluate the Geological Controls on Low-Sulphidation Epithermal Au-Ag mineralisation in the Drummond and Bowen Basins, Australia

    Science.gov (United States)

    Feltrin, Leonardo; Baker, Timothy; Oliver, Nick; Scott, Margaretha; Wilkinson, Kate; Fitzell, Melanie; Dixon, Owen; Bertelli, Martina

    2008-05-01

    We present a 3D geological model that integrates different datasets and incorporates geophysical inversion of airborne gravimetric and magnetic surveys of the northern part of the Drummond and Bowen basins. These basins are known for their endowment of low-sulphidation, epithermal Au-Ag mineralisation. The objective of this computer based reconstruction is to empirically evaluate the key controlling variables that contributed to the spatial localization of 147 Palaeozoic and Mesozoic shallow hydrothermal gold systems, found predominantly in veins and breccia hosted in basal volcanics and volcaniclastic intervals developed in a back-arc rift environment. The model provides a three-dimensional, regional scale (100,000 km2) perspective on the spatial associations between geology, structure, magmatism and known mineral occurrences, representing a 3D framework for precious-metals exploration. Results of 3D visualisation of geological and geophysical data suggest that magmatic intrusions, and correlative volcanic centres localized most of the major deposits and also controlled the arrangement of clusters of uneconomic Au-Ag occurrences. The empirical modelling supports a model for the genesis of low-sulphidation epithermal Au-Ag mineralisation that favours a strong spatial association with shallow felsic to intermediate magmatic intrusions, similarly to that proposed for high-sulphidation systems. Geophysical inversion estimates for the depth of magmatic bodies suggest also that they may have controlled the efficiency of the hydrothermal, mineralising systems-shallow intrusions tend to be associated with greater tonnages of Au-Ag and are spatially associated with the larger clusters of occurrences. However, the composition of magmatic intrusions (mafic, intermediate, felsic) may have been important in regulating the amount of available bisulphide in the volatile phase, exerting a control on Au grade/tonnage independent of the depth of emplacement of intrusions.

  13. Static and dynamic behaviour of composite structures with shape memory alloy components

    Energy Technology Data Exchange (ETDEWEB)

    Zak, A.J.; Cartmell, M.P. [Glasgow Univ. (United Kingdom). Dept. of Mechanical Engineering; Ostachowicz, W.M. [Polska Akademia Nauk, Gdansk (Poland). Inst. of Fluid Flow Machinery

    2003-07-01

    In this work selected results have been presented for the static and dynamic behaviour of composite beams, plates, and rotors, all fitted with integral SMA wires or strips. Changes in the static deflections, natural frequencies and critical loads, natural modes, amplitudes of forced vibration, and stress distributions, have all been investigated. Applications of the Active Property Tuning (APT) method and the Active Strain Energy Tuning (ASET) method have been proposed, and the finite element method (FEM) has been used to calculate the static and dynamic responses of these structures. Along with the author's bespoke programs, two FEM commercial packages PATRAN and ABAQUS have been applied to obtain the relevant data. The ultimate intention is to use embedded SMAs within a composite structure as an actuator for the control of rotor vibration. (orig.)

  14. Green synthesis, characterization of Au-Ag core-shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    Science.gov (United States)

    Kirubha, E.; Palanisamy, P. K.

    2014-12-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au-Ag bimetallic core-shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au-Ag nanoparticles are characterized using UV-Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 109. The nonlinear optical parameters such as the nonlinear refractive index n2, nonlinear absorption coefficient β and the third order nonlinear susceptibility χ3 are measured for various wavelengths from 700 nm to 950 nm. The Au-Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G.

  15. 3D modelling and sheath folding at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Stephens, Michael B.; Weihed, Pär

    2016-06-01

    Altered and mineralized rocks at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic Bergslagen ore district in the south-western part of the Fennoscandian Shield, have been metamorphosed at low-pressure, amphibolite-facies conditions and affected by ductile deformation. Using combined surface mapping of lithology and structure, drill core logging and microstructural work, the polyphase (D1 and D2) ductile deformation is demonstrated and a 3D model for the deposit created. Mineral associations include quartz, biotite, cordierite, anthophyllite, and minor almandine, andalusite and chlorite in silicate-rich altered rock, calcite or dolomite in marble and tremolite-actinolite or diopside-hedenbergite in skarn. The silicate minerals show varying growth patterns during the different phases of the tectonothermal evolution, with considerable static grain growth occurring between D1 and D2, and even after D2. F2 sheath folding along axes that plunge steeply to the SSE, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, cone- to rod-shaped mineralized bodies. This contrasts with a previous structural model invoking fold interference. A major shear zone with talc-chlorite-(quartz-biotite) mineral association separates the northern and southern structural domains at the deposit and bounds the polymetallic massive sulphides to the north.

  16. 3D modelling and sheath folding at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit and implications for exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Stephens, Michael B.; Weihed, Pär

    2016-01-01

    Altered and mineralized rocks at the Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic Bergslagen ore district in the south-western part of the Fennoscandian Shield, have been metamorphosed at low-pressure, amphibolite-facies conditions and affected by ductile deformation. Using combined surface mapping of lithology and structure, drill core logging and microstructural work, the polyphase (D1 and D2) ductile deformation is demonstrated and a 3D model for the deposit created. Mineral associations include quartz, biotite, cordierite, anthophyllite, and minor almandine, andalusite and chlorite in silicate-rich altered rock, calcite or dolomite in marble and tremolite-actinolite or diopside-hedenbergite in skarn. The silicate minerals show varying growth patterns during the different phases of the tectonothermal evolution, with considerable static grain growth occurring between D1 and D2, and even after D2. F2 sheath folding along axes that plunge steeply to the SSE, parallel to a mineral stretching lineation and the dip direction of the S2 foliation, is suggested as a key deformation mechanism forming steeply plunging, cone- to rod-shaped mineralized bodies. This contrasts with a previous structural model invoking fold interference. A major shear zone with talc-chlorite-(quartz-biotite) mineral association separates the northern and southern structural domains at the deposit and bounds the polymetallic massive sulphides to the north.

  17. Ultra-fine ferrite grain refinement by static re-crystallization of hot rolled vanadium micro-alloyed steels

    International Nuclear Information System (INIS)

    The phenomenon of ultrafine-grain refinement of ferrite during transformational grain refinement (TGR) followed by static re-crystallization of vanadium micro-alloyed steels was studied. A substantial grain refinement (2.8 mu m) was attained during TGR process by rolling at 900 deg. C. Cold rolling with 70% of reduction introduced strain, utilized for re-crystallization during annealing at different temperatures. Electron Backscattered Diffraction (EBSD) technique was employed to quantify the low angle grain boundaries (LAGB) and high angle grain boundaries (HAGB) spacings and results were correlated with hardness drops during annealing process. At higher annealing times and temperatures the vanadium precipitates restricted the process of grain growth probably due to effective dispersion strengthening. The abnormal grain growth during annealing, predicted previously for niobium steels, found absent in the present vanadium microalloyed steels. (author)

  18. Static critical phenomena in Co-Ni-Ga ferromagnetic shape memory alloy

    International Nuclear Information System (INIS)

    Ferromagnetic shape memory alloys are smart materials because they exhibit temperature driven shape memory effect and magnetic field induced strain. Thus two types of energy, i.e. thermal and magnetic, are used to control their shape memory behaviour. Study of critical phenomenon in such materials has received increased experimental and theoretical attention for better understanding of the magnetic phase transition behavior as well as further development of ferromagnetic shape memory materials. In the present study we report the preparation and characterization of bulk Co45Ni25Ga30 alloy, prepared by a sequence of arc melting technique followed by homogenization at 1150 °C for 24 hours and ice-water quenching. Structural and magnetic properties of the alloys were studied by means of X-ray diffraction and vibrating sample magnetometer in an applied field range of ±18 kOe equipped with a high temperature oven. We have determined the critical temperature TC (∼375.5 K) and the critical exponents viz; β=0.40, γ=1.68 and δ=5.2. Asymptotic critical exponents β, γ, and δ obey Widom scaling relation, γ+β=βδ, and the magnetization data satisfy the scaling equation of state for second-order phase transition in the asymptotic critical region

  19. Nano-Crystal Formation and Growth from High-Fluence Ion Implantation of Au, Ag or Cu in Silica

    Science.gov (United States)

    Ila, D.; Baglin, J. E. E.; Zimmerman, R. L.

    The linear and non-linear optical properties of silica may be tailored by the introduction of a random distribution of nanocrystallites of an immiscible metal within a near-surface region. The size, size distribution, and spatial distribution of these crystallites must be controllable in order to optimize the functional properties for device applications. In this paper, we present a novel fabrication technique that offers such control. Energetic metal ions are implanted in silica at room temperature. Subsequent heat treatment leads to diffusion of the implanted atoms, nucleation and growth of metal crystallites, and Ostwald ripening of the resulting clusters. We have observed the kinetics and effective activation energies describing the multiple processes involved, for the cases of Au, Ag or Cu implanted at MeV energies, at various fluences, and then annealed at fixed temperatures in the range 500 °C-1000 °C. Effective activation energies found for nanocrystal nucleation and growth at temperatures below 800 °C (e.g. 64 meV for Ag) are replaced above this temperature range by much higher activation energies (e.g. 400 meV for Ag). We may attribute this to the depletion of un-attached mobile metal atoms (so that ripening of clusters will be limited by energy barriers for escape of such mobile atoms from small crystallites), and/or the annealing of implant-caused stress in the silica structure at high temperatures, that creates new channels for thermal diffusion of metal atoms within the silica host.

  20. Effect of structural factors on mechanical properties of the magnesium alloy Ma2-1 under quasi-static and high strain rate deformation conditions

    Science.gov (United States)

    Garkushin, G. V.; Razorenov, S. V.; Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.

    2015-02-01

    The elastic limit and tensile strength of deformed magnesium alloys Ma2-1 with different structures and textures were measured with the aim of finding a correlation between the spectrum of defects in the material and the resistance to deformation and fracture under quasi-static and dynamic loading conditions. The studies were performed using specimens in the as-received state after high-temperature annealing and specimens subjected to equal-channel angular pressing at a temperature of 250°C. The anisotropy of strength characteristics of the material after shock compression with respect to the direction of rolling of the original alloy was investigated. It was shown that, in contrast to the quasi-static loading conditions, under the shock wave loading conditions, the elastic limit and tensile strength of the magnesium alloy Ma2-1 after equal-channel angular pressing decrease as compared to the specimens in the as-received state.

  1. Static and cyclic creep properties of three forms of a cast nickel alloy

    International Nuclear Information System (INIS)

    The static and cyclic creep properties of conventionally cast, directionally solidified and single crystal forms of a cast nickel superalloy, Mar M246, have been evaluated at 850 and 9000C. Tensile and compressive creep curves have been obtained at constant stress and the results analyzed using power law creep terms. Typically, directionally solidified specimens have tensile lives twice those of comparable conventionally cast materials, and rupture strains three or four times greater. Increase in specimen size raised the life of conventionally cast material but had no effect on single crystals. Differences between tensile and compressive creep properties were accentuated in the tertiary stages of deformation. No improvement in compressive creep resistance was obtained using directionally solidified or single crystal specimens. Equations developed previously from strain hardening theory gave an accurate estimation of behavior under cyclic tension. This theory has been extended to include push-pull loading and is shown to give a satisfactory correlation with the data

  2. Static and dynamic magnetic properties of epitaxial Co2FeAl Heusler alloy thin films

    Science.gov (United States)

    Ortiz, G.; Gabor, M. S.; Petrisor, T., Jr.; Boust, F.; Issac, F.; Tiusan, C.; Hehn, M.; Bobo, J. F.

    2011-04-01

    Structural and magnetic properties of epitaxial Co2FeAl Heusler alloy thin films were investigated. Films were deposited on single crystal MgO (001XS) substrates at room temperature, followed by an annealing process at 600 °C. MgO and Cr buffer layers were introduced in order to enhance crystalline quality, and improve magnetic properties. Structural analyses indicate that samples have grown in the B2 ordered epitaxial structure. VSM measures show that the MgO buffered sample displays a magnetization saturation of 1010 ± 30 emu/cm3, and Cr buffered sample displays a magnetization saturation of 1032 ± 40 emu/cm3. Damping factor was studied by strip-line ferromagnetic resonance measures. We observed a maximum value for the MgO buffered sample of about 8.5 × 10-3, and a minimum value of 3.8 × 10-3 for the Cr buffered one.

  3. Statistical analysis on static recrystallization texture evolution in cold-rolled AZ31 magnesium alloy sheet.

    Science.gov (United States)

    Park, Jun-Ho; Ahn, Tae-Hong; Choi, Hyun-Sik; Chung, Jung-Man; Kim, Dong-Ik; Oh, Kyu Hwan; Han, Heung Nam

    2013-08-01

    Cast AZ31B-H24 magnesium alloy, comprising Mg with 3.27 wt% Al and 0.96 wt% Zn, was cold rolled and subsequently annealed. Global texture evolutions in the specimens were observed by X-ray diffractometry after the thermomechanical processing. Image-based microstructure and texture for the deformed, recrystallized, and grown grains were observed by electron backscattered diffractometry. Recrystallized grains could be distinguished from deformed ones by analyzing grain orientation spread. Split basal texture of ca. ±10-15° in the rolling direction was observed in the cold-rolled sample. Recrystallized grains had widely spread basal poles at nucleation stage; strong {0001} basal texture developed with grain growth during annealing. PMID:23920167

  4. Au@Ag/Au nanoparticles assembled with activatable aptamer probes as smart ``nano-doctors'' for image-guided cancer thermotherapy

    Science.gov (United States)

    Shi, Hui; Ye, Xiaosheng; He, Xiaoxiao; Wang, Kemin; Cui, Wensi; He, Dinggeng; Li, Duo; Jia, Xuekun

    2014-07-01

    Although nanomaterial-based theranostics have increased positive expectations from cancer treatment, it remains challenging to develop in vivo ``nano-doctors'' that provide high-contrast image-guided site-specific therapy. Here we designed an activatable theranostic nanoprobe (ATNP) via self-assembly of activatable aptamer probes (AAPs) on Au@Ag/Au nanoparticles (NPs). As both quenchers and heaters, novel Au@Ag/Au NPs were prepared, showing excellent fluorescence quenching and more effective near-infrared photothermal therapy than Au nanorods. The AAP comprised a thiolated aptamer and a fluorophore-labeled complementary DNA; thus, the ATNP with quenched fluorescence in the free state could realize signal activation through target binding-induced conformational change of the AAP, and then achieve on-demand treatment under image-guided irradiation. By using S6 aptamer as the model, in vitro and in vivo studies of A549 lung cancer verified that the ATNP greatly improved imaging contrast and specific destruction, suggesting a robust and versatile theranostic strategy for personalized medicine in future.Although nanomaterial-based theranostics have increased positive expectations from cancer treatment, it remains challenging to develop in vivo ``nano-doctors'' that provide high-contrast image-guided site-specific therapy. Here we designed an activatable theranostic nanoprobe (ATNP) via self-assembly of activatable aptamer probes (AAPs) on Au@Ag/Au nanoparticles (NPs). As both quenchers and heaters, novel Au@Ag/Au NPs were prepared, showing excellent fluorescence quenching and more effective near-infrared photothermal therapy than Au nanorods. The AAP comprised a thiolated aptamer and a fluorophore-labeled complementary DNA; thus, the ATNP with quenched fluorescence in the free state could realize signal activation through target binding-induced conformational change of the AAP, and then achieve on-demand treatment under image-guided irradiation. By using S6 aptamer as

  5. The Nature of the Binding of Au, Ag, and Pd to Benzene, Coronene, and Graphene: From Benchmark CCSD(T) Calculations to Plane-Wave DFT Calculations

    OpenAIRE

    Granatier, Jaroslav; Lazar, Petr; Otyepka, Michal; Hobza, Pavel

    2011-01-01

    The adsorption of Ag, Au, and Pd atoms on benzene, coronene, and graphene has been studied using post Hartree–Fock wave function theory (CCSD(T), MP2) and density functional theory (M06-2X, DFT-D3, PBE, vdW-DF) methods. The CCSD(T) benchmark binding energies for benzene–M (M = Pd, Au, Ag) complexes are 19.7, 4.2, and 2.3 kcal/mol, respectively. We found that the nature of binding of the three metals is different: While silver binds predominantly through dispersion interactions, the binding of...

  6. Static and Dynamic Magnetization of Gradient FeNi Alloy Nanowire.

    Science.gov (United States)

    Yang, Haozhe; Li, Yi; Zeng, Min; Cao, Wei; Bailey, William E; Yu, Ronghai

    2016-01-01

    FeNi binary nanowires with gradient composition are fabricated by the electrodeposition method. The energy dispersive spec-trometer line-sweep results show that the composition changes gradually along the wire axis. The gradient FeNi nanowires exhibit polycrystalline and crystal twinning at different areas along the nanowire axis, with a textured face-centered cubic structure. The static and dynamic magnetization properties are characterized by a hysteresis loop and ferromagnetic reso-nance with pumping frequencies from 12- 40 GHz. The linear dispersion of the pumping frequency vs: the resonance field has been observed with the applied bias field higher than the saturation field, corresponding to the hysteresis loop. The field-sweep linewidths decrease with increasing pumping frequency, and the frequency-sweep linewidths stay nearly constant at the unsaturated region. The linewidth is a Gilbert type at the saturated state, with damping of 0.035 ± 0.003. Compared with the damping of the homogeneous composition FeNi nanowire (a = 0.044 ± 0.005), the gradient FeNi nanowire may have less eddy current damping, which could make it an alternative candidate for spintronics and microstrip antennas. PMID:26864282

  7. Microstructure and texture evolution during static recrystallization of Zr-2Hf alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, K.Y.; Chaubet, D.; Bacroix, B.; Bechade, J.L. [MPMTM-CNRS, Inst. Galilee, Univ. Paris-Nord, Villetaneuse (France); CEA SACLAY, CEREM/DECM/SRMA, Gif-fur-Yvette (France)

    2004-07-01

    The recrystallization of a Zr-2Hf alloy sheet deformed by plane strain compression at room temperature and then heat treated in the temperature range 500-650 C is studied. The microstructure, local and global crystallographic textures are investigated by EBSD and X-ray techniques. The as-deformed condition exhibits a heterogeneous microstructure composed of highly and less deformed zones, the EBSD indexing of the latter ones being more reliable. The as-deformed condition displays a (0001) <10 anti 10> crystallographic texture. The evolution of the microstructure during recrystallization very much depends on the amount of local deformation. Recrystallization begins in highly deformed zones, new grains having two variants of texture components, {l_brace}0001{r_brace} <10 anti 10> and {l_brace}0001{r_brace} <11 anti 20>. Some change of preferred orientations concomitant with grain growth at 600 and 650 C has been observed with a decrease in the {l_brace}0001{r_brace} <10 anti 10> component and an increase in the {l_brace}0001{r_brace} <11 anti 20> component. (orig.)

  8. Silver-rich telluride mineralization at Mount Charlotte and Au-Ag zonation in the giant Golden Mile deposit, Kalgoorlie, Western Australia

    Science.gov (United States)

    Mueller, Andreas G.; Muhling, Janet R.

    2013-03-01

    The gold deposits at Kalgoorlie in the 2.7-Ga Eastern Goldfields Province of the Yilgarn Craton, Western Australia, occur adjacent to the D2 Golden Mile Fault over a strike of 8 km within a district-scale zone marked by porphyry dykes and chloritic alteration. The late Golden Pike Fault separates the older (D2) shear zone system of the Golden Mile (1,500 t Au) in the southeast from the younger (D4) quartz vein stockworks at Mt Charlotte (126 t Au) in the northwest. Both deposits occur in the Golden Mile Dolerite sill and display inner sericite-ankerite alteration and early-stage gold-pyrite mineralization replacing the wall rocks. Late-stage tellurides account for 20 % of the total gold in the first, but for 30 g/t Au) is characterized by Au/Ag = 2.54 and As/Sb = 2.6-30, the latter ratio caused by arsenical pyrite. Golden Mile-type D2 lodes occur northwest of the Golden Pike Fault, but the Hidden Secret orebody, the only telluride bonanza mined (10,815 t at 44 g/t Au), was unusually rich in silver (Au/Ag = 0.12-0.35) due to abundant hessite. We describe another array of silver-rich D2 shear zones which are part of the Golden Mile Fault exposed on the Mt Charlotte mine 22 level. They are filled with crack-seal and pinch-and-swell quartz-carbonate veins and are surrounded by early-stage pyrite + pyrrhotite disseminated in a sericite-ankerite zone more than 6 m wide. Gold grade (0.5-0.8 g/t) varies little across the zone, but Au/Ag (0.37-2.40) and As/Sb (1.54-13.9) increase away from the veins. Late-stage telluride mineralization (23 g/t Au) sampled in one vein has a much lower Au/Ag (0.13) and As/Sb (0.48) and comprises scheelite, pyrite, native gold (830-854 fine), hessite, and minor pyrrhotite, altaite, bournonite, and boulangerite. Assuming 250-300 °C, gold-hessite compositions indicate a fluid log f Te2 of -11.5 to -10, values well below the stability of calaverite. The absence of calaverite and the dominance of hessite in the D2 lodes of the Mt Charlotte area

  9. High strain in polycrystalline Ni48.8Mn31.4Ga19.8 Heusler alloys under overlapped static and oscillating magnetic fields

    International Nuclear Information System (INIS)

    Martensitic polycrystalline Ni48.8Mn31.4Ga19.8 Heusler alloys, with a stacking period of 14 atomic planes at room temperature, were innovatively processed by combining high-energy ball milling and powder metallurgy. Bulk samples were mechanically coupled to a piezoelectric material in a parallel configuration, and the mechanical deformation of the studied system due to the twin's variant motion was investigated under overlapped static and oscillating magnetic fields. A reversible and high mechanical deformation is observed when the frequency of the oscillating magnetic field is tuned with the natural vibration frequency of this system. In this condition, a linear deformation as a function of the static magnetic field amplitude occurs in the ±4 kOe range, and a mechanical deformation of 2% at 10 kOe is observed.

  10. Surface asperity evolution and microstructure analysis of Al 6061T5 alloy in a quasi-static cold uniaxial planar compression (CUPC)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hejie, E-mail: hejiel2003@gmail.com [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Jiang, Zhengyi, E-mail: jiang@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Wei, Dongbin [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); School of Electrical, Mechanical and Mechatronic Systems, University of Technology, Sydney, NSW 2007 (Australia); Gao, Xingjian [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Xu, Jianzhong; Zhang, Xiaoming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, Liaoning 110004 (China)

    2015-08-30

    Highlights: • We used AFM and EBSD to analyses the surface asperity flattening process. • Analysis of the influence of deformation rate on the surface asperity flattening. • Investigation of the effect of lubrication on microstructure development. • Deformation rate influence the generation of orientation components obviously. - Abstract: In a quasi-static cold uniaxial planar compression, surface asperity evolution and microstructure analysis of Al 6061T5 alloy are carried out by employing Atomic Force Microscope (AFM) and Electron Backscattered Diffraction (EBSD) methods. Strain rate affects the surface asperity evolution obviously. While lubrication can hinder the surface asperity flattening by constraining the surface localized deformation. Lubrication can accelerate the crystallization in CUPC process. It also impedes the activation of some orientation components by hindering the activation of related slip systems in light metal Al alloy.

  11. Surface asperity evolution and microstructure analysis of Al 6061T5 alloy in a quasi-static cold uniaxial planar compression (CUPC)

    International Nuclear Information System (INIS)

    Highlights: • We used AFM and EBSD to analyses the surface asperity flattening process. • Analysis of the influence of deformation rate on the surface asperity flattening. • Investigation of the effect of lubrication on microstructure development. • Deformation rate influence the generation of orientation components obviously. - Abstract: In a quasi-static cold uniaxial planar compression, surface asperity evolution and microstructure analysis of Al 6061T5 alloy are carried out by employing Atomic Force Microscope (AFM) and Electron Backscattered Diffraction (EBSD) methods. Strain rate affects the surface asperity evolution obviously. While lubrication can hinder the surface asperity flattening by constraining the surface localized deformation. Lubrication can accelerate the crystallization in CUPC process. It also impedes the activation of some orientation components by hindering the activation of related slip systems in light metal Al alloy

  12. M\\TiO₂ (M=Au, Ag) transparent aqueous sols and its application on polymeric surface antibacterial post-treatment.

    Science.gov (United States)

    Wu, Liangzhuan; Yu, Yuan; Song, Le; Zhi, Jinfang

    2015-05-15

    In this paper, we reported a simple and mild chemical method for synthesis of crystalline metal\\TiO2 (M=Au, Ag) transparent aqueous sols at low temperature (80°C). It should be found that the as-synthesized metal\\TiO2 sols could easily be coated on the flexible PET surfaces of the through the as-developed electroless-plating-like solution deposition (EPLSD) procedure. The as-prepared metal\\TiO2 sols and related flexible thin film were characterized by TEM, SEM, XRD, UV-vis, and FTIR analysis. The results showed that the Au and Ag nanoparticles can significantly improve the optical absorption properties of TiO2 due to the surface plasmon generated by the noble metal, which in turn enhanced the photo-induced antibacterial performance of the as-prepared metal\\TiO2 flexible film. Moreover, the photo-generated electrons could transfer between the metal and titanium dioxide under different irradiation (ultraviolet or visible light), which could significantly reduce the recombination of photo-induced electrons and holes, resulting in the better photo-induced antibacterial performance. Therefore, the EPLSD procedure may be used as a general polymeric surface antibacterial post-treatment procedure for preparing the metal\\TiO2 flexible film because of the noble metal enhanced antibacterial performance. PMID:25678155

  13. Simultaneous enzymatic and SERS properties of bifunctional chitosan-modified popcorn-like Au-Ag nanoparticles for high sensitive detection of melamine in milk powder.

    Science.gov (United States)

    Li, Junrong; Zhang, Guannan; Wang, Lihua; Shen, Aiguo; Hu, Jiming

    2015-08-01

    In this work, we suggest a chitosan-modified popcorn-like Au-Ag nanoparticles (CSPNPs) based assay for high sensitive detection of melamine, in which CSPNPs not only provide with an intrinsic peroxidase-like activity but also act as surface enhanced Raman scattering (SERS) substrates. CSPNPs can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to the charge transfer complex (CTC), which contributes to a tremendous surface-enhanced resonant Raman scattering (SERRS) signals with 632.8 nm laser excitation. The target molecule melamine can generate an additional compound with H2O2, which means the available amount of H2O2 for the oxidation of TMB reduced. Correspondingly, the SERRS intensity of CTC is decreased. The decreased Raman intensity is proportional to the concentration of melamine over a wide range from 10 nM to 50 μM (R(2)=0.989), with a limit of detection (LOD) of 8.51 nM. Moreover, the proposed highly selective method is fully capable of rapid, separation-free detection of melamine in milk powder. PMID:26048843

  14. Target-specific near-IR induced drug release and photothermal therapy with accumulated Au/Ag hollow nanoshells on pulmonary cancer cell membranes.

    Science.gov (United States)

    Noh, Mi Suk; Lee, Somin; Kang, Homan; Yang, Jin-Kyoung; Lee, Hyunmi; Hwang, Doyk; Lee, Jong Woo; Jeong, Sinyoung; Jang, Yoonjeong; Jun, Bong-Hyun; Jeong, Dae Hong; Kim, Seong Keun; Lee, Yoon-Sik; Cho, Myung-Haing

    2015-03-01

    Au/Ag hollow nanoshells (AuHNSs) were developed as multifunctional therapeutic agents for effective, targeted, photothermally induced drug delivery under near-infrared (NIR) light. AuHNSs were synthesized by galvanic replacement reaction. We further conjugated antibodies against the epidermal growth factor receptor (EGFR) to the PEGylated AuHNS, followed by loading with the antitumor drug doxorubicin (AuHNS-EGFR-DOX) for lung cancer treatment. AuHNSs showed similar photothermal efficiency to gold nanorods under optimized NIR laser power. The targeting of AuHNS-EGFR-DOX was confirmed by light-scattering images of A549 cells, and doxorubicin release from the AuHNSs was evaluated under low pH and NIR-irradiated conditions. Multifunctional AuHNS-EGFR-DOX induced photothermal ablation of the targeted lung cancer cells and rapid doxorubicin release following irradiation with NIR laser. Furthermore, we evaluated the effectiveness of AuHNS-EGFR-DOX drug delivery by comparing two drug delivery methods: receptor-mediated endocytosis and cell-surface targeting. Accumulation of the AuHNS-EGFR-DOX on the cell surfaces by targeting EGFR turned out to be more effective for lung cancer treatments than uptake of AuHNS-EGFR-DOX. Taken together, our data suggest a new and optimal method of NIR-induced drug release via the accumulation of targeted AuHNS-EGFR-DOX on cancer cell membranes. PMID:25662498

  15. Enhancement of chitosan-graphene oxide SPR sensor with a multi-metallic layers of Au-Ag-Au nanostructure for lead(II) ion detection

    Science.gov (United States)

    Kamaruddin, Nur Hasiba; Bakar, Ahmad Ashrif A.; Yaacob, Mohd Hanif; Mahdi, Mohd Adzir; Zan, Mohd Saiful Dzulkefly; Shaari, Sahbudin

    2016-01-01

    We demonstrate the enhancement of surface plasmon resonance (SPR) technique by implementing a multi-metallic layers of Au-Ag-Au nanostructure in the chitosan-graphene oxide (CS-GO) SPR sensor for lead(II) ion detection. The performance of the sensor is analyzed via SPR measurements, from which the sensitivity, signal-to-noise ratio and repeatability are determined. The nanostructure layers are characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). We showed that the proposed structure has increased the shift in the SPR angle up to 3.5° within the range of 0.1-1 ppm due to the enhanced evanescent field at the sensing layer-analyte interface. This sensor also exhibits great repeatability which benefits from the stable multi-metallic nanostructure. The SNR value of 0.92 for 5 ppm lead(II) ion solution and reasonable linearity range up to that concentration shows that the tri-metallic CS-GO SPR sensor gives a good response towards the lead(II) ion solution. The CS-GO SPR sensor is also sensitive to at least a 10-5 change in the refractive index. The results prove that our proposed tri-metallic CS-GO SPR sensor demonstrates a strong performance and reliability for lead(II) ion detection in accordance with the standardized lead safety level for wastewater.

  16. Effect of metal primers and tarnish treatment on bonding between dental alloys and veneer resin

    OpenAIRE

    Choo, Seung-Sik; Huh, Yoon-Hyuk; Cho, Lee-Ra; Park, Chan-Jin

    2015-01-01

    PURPOSE The aim of this study was to evaluate the effect of metal primers on the bonding of dental alloys and veneer resin. Polyvinylpyrrolidone solution's tarnish effect on bonding strength was also investigated. MATERIALS AND METHODS Disk-shape metal specimens (diameter 8 mm, thickness 1.5 mm) were made from 3 kinds of alloy (Co-Cr, Ti and Au-Ag-Pd alloy) and divided into 4 groups per each alloy. Half specimens (n=12 per group) in tarnished group were immersed into polyvinylpyrrolidone solu...

  17. Electrochemiluminescence immunosensing strategy based on the use of Au-Ag nanorods as a peroxidase mimic and NH4CoPO4 as a supercapacitive supporter: Application to the determination of carcinoembryonic antigen

    International Nuclear Information System (INIS)

    The luminol-H2O2 system is widely applied in electrochemiluminescence (ECL) assays but has limited stability. We are presenting an alternative immunosensing strategy by making use of Au-Ag nanorods that mimic the enzyme peroxidase. It also makes use of the supercapacitive supporter NH4CoPO4 as a supporter substrate that facilitates ion movement due to its many nanogaps between the assembled nanoplates. It also plays a vital role for stabilizing the ECL signal of luminol. The immunosensor was constructed by first placing a chitosan film containing NH4CoPO4, Au-Ag and luminol on a glassy carbon electrode (GCE), and the immobilizing anti-CEA on its surface. ECL is generated via electrochemical reaction of luminol on the surface of the Au-Ag-luminol film in the presence of H2O2. The assay was evaluated with respect to effects of pH value, time and temperature of incubation, specificity, reproducibility, and stability in a lab setting. A linear relationship between ECL intensity and CEA concentration is found for the 0.1 pg · mL−1 to 380 ng · mL−1 range, and the lower detection limit is as low as 30 fg · mL−1. In our perception, this immunoassay has a large scope in that numerous other immunoassays will become feasible by using other antibodies and, possibly, aptamers. (author)

  18. Broadband optical absorption enhancement of N719 dye in ethanol by gold-silver alloy nanoparticles fabricated under laser ablation technique

    Science.gov (United States)

    Al-Azawi, Mohammed A.; Bidin, Noriah; Abbas, Khaldoon N.; Bououdina, Mohamed; Azzez, Shrook A.

    2016-04-01

    The formation of gold-silver alloy nanoparticles (Au-Ag alloy NPs) by a two-step process with a pulsed Nd:YAG laser without any additives is presented. Mixtures of Au and Ag colloidal suspensions were separately obtained by 1064-nm laser ablation of metallic targets immersed in ethanol. Subsequently, the as-mixed colloidal suspensions were reirradiated by laser-induced heating at the second-harmonic generation (532 nm) for different irradiation periods of time. The absorption spectra and morphology of the colloidal alloys were studied as a function of exposure time to laser irradiation. Transmission electron microscopy revealed the formation of monodispersed spherical nanoparticles with a homogeneous size distribution in all the synthesized samples. UV-vis and photoluminescence spectroscopy measurements were also employed to characterize the changes in the light absorption and emission of N719 dye solution with different concentrations of Au-Ag colloidal alloys, respectively. The localized surface plasmon resonance (LSPR) of Au-Ag alloy NPs enhanced the absorption and fluorescence peak of the dye solution. The mixture of dye molecules with a higher concentration of alloy NPs exhibited an additional coupling of dipole moments with the LSPR, thereby contributing to the improvement of the optical properties of the mixture.

  19. Abatement of segregation with the electro and static magnetic field during twin-roll casting of 7075 alloy sheet

    Energy Technology Data Exchange (ETDEWEB)

    Su, X. [The Key Laboratory of Electromagnetic Processing of Material, Ministry of Education, 317#, Northeastern University, Shenyang, 110819 Liaoning (China); Xu, G.M., E-mail: Xu_gm@epm.neu.edu.cn [The Key Laboratory of Electromagnetic Processing of Material, Ministry of Education, 317#, Northeastern University, Shenyang, 110819 Liaoning (China); Jiang, D.H. [Donggong Information Science and Technology Co., Ltd., Guangzhou, 510000 Guangdong (China)

    2014-04-01

    This study aims to investigate the influence of electromagnetic field on the distribution and composition of precipitates and on the mechanical properties of 7075 rolled sheets. The non-field and field microstructure and the mechanical properties were studied in detail by optical microscope (OM), electron probe microanalyzer (EPMA), multiple sample tensile as well as hardness tests. The Fine and equiaxed grains were obtained when introducing the alternating oscillating electromagnetic field to the twin-roll casting (TRC) process with 0.13 T static magnetic and 386 A alternating current (AC) intensities. Due to a damping effect on the convection generated by applying the electro- and static magnetic fields, the undercooling of the melt decreases and the continuous net-like precipitates are refined and broken remarkably. Especially under oscillating electromagnetic field conditions, the best uniform microstructure without mottled segregation was obtained. In addition, the fields can effectively enhance solute mixing capacity and reduce heat discharge, resulting in the increase of mechanical properties of 7075 sheets in both the longitudinal and long transverse directions. The optimum process in the present study, in which the higher solid solubility in Al matrix and the stronger hardness as well as tensile strength was gained as compared to other rolled specimens, is considered as alternating oscillating TRC process.

  20. Mesoscale Modeling and Validation of Texture Evolution during Asymmetric Rooling and Static Recrystallization of Magnesium Alloy AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, Balasubramaniam [ORNL; Gorti, Sarma B [ORNL; Stoica, Grigoreta M [ORNL; Muralidharan, Govindarajan [ORNL; Stoica, Alexandru Dan [ORNL; Wang, Xun-Li [ORNL; Specht, Eliot D [ORNL; Kenik, Edward A [ORNL; Muth, Thomas R [ORNL

    2012-01-01

    The focus of the present research is to develop an integrated deformation and recrystallization model for magnesium alloys at the microstructural length scale. It is known that in magnesium alloys nucleation of recrystallized grains occurs at various microstructural inhomogeneities such as twins and localized deformation bands. However, there is a need to develop models that can predict the evolution of the grain structure and texture developed during recrystallization and grain growth, especially when the deformation process follows a complicated deformation path such as in asymmetric rolling. The deformation model is based on a crystal plasticity approach implemented at the length scale of the microstructure that includes deformation mechanisms based on dislocation slip and twinning. The recrystallization simulation is based on a Monte Carlo technique that operates on the output of the deformation simulations. The nucleation criterion during recrystallization is based on the local stored energy and the Monte Carlo technique is used to simulate the growth of the nuclei due to local stored energy differences and curvature. The model predictions are compared with experimental data obtained through electron backscatter analysis and neutron diffraction.

  1. An electrochemical analysis of AZ91 Mg alloy processed by plasma electrolytic oxidation followed by static annealing

    International Nuclear Information System (INIS)

    Research highlights: → The amount of MgO in the oxide film increased with increasing annealing temperature. → The dehydration reaction resulted in the formation of micro-cracks in the oxide film. → Electrochemical response of the PEO-treated sample annealed at 150 deg. C was improved. - Abstract: In this study, the effect of subsequent annealing on the electrochemical response of AZ91 Mg alloy coated via plasma electrolytic oxidation (PEO) was investigated. PEO coating was carried out on the Mg alloy under AC condition in an alkaline silicate electrolyte, and the PEO-coated samples underwent several subsequent annealing treatments at three different temperatures of 100, 150, and 200 deg. C. The surface morphologies of the coating layers were observed via a scanning electron microscope (SEM) and their constituent compounds were characterized by qualitative observation based on X-ray photoelectron spectroscopy (XPS). In addition, the corrosion protection properties of the PEO-coated sample were examined by electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution with a focus on exploring the effect of subsequent annealing on the electrochemical response in a quantitative manner. SEM and XPS observations evidenced that the subsequent annealing at temperatures higher than 150 deg. C resulted in significant morphological changes due to the dehydration reaction of Mg(OH)2 to form MgO. Thus, it was found that the sample annealed at 150 deg. C exhibited a better corrosion resistance than the other samples, which were analyzed by taking an equivalent circuit model into account.

  2. Energy Parameters of Interfacial Layers in Composite Systems: Graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and Semiconductor (Si,Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb

    Directory of Open Access Journals (Sweden)

    B.P. Koman

    2015-12-01

    Full Text Available On the basis of the non-equilibrium thermodynamics relations and the surface physics phenomena we calculate adhesion and energy parameters to characterize the interfacial interactions in graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and semiconductor (Si, Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb systems. We analyze trends of the interfacial energy, interfacial tension, work of adhesion and the energy of adhesive bonds on the contacting element’s atomic number in the periodic table and on the electronegativity difference of interacting elements. Thus, this work provides theoretical basis for the development of new composite materials.

  3. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    Science.gov (United States)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-08-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with measured fluid inclusion temperatures. A striking aspect of the Marianas-San Marcos vein system is that the high

  4. Organic Gases in Fluid Inclusions of Ore Minerals and Their Constraints on Ore Genesis: A Case Study of the Changkeng Au-Ag Deposit, Guangdong, China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The newly discovered Changkeng Au-Ag deposit is a new type of sediment-hosted precious metal deposit. Most of the previous researchers believed that the deposit was formed by meteoric water convection. By using a high vacuum quadrupole gas mass spectrometric system, nine light hydrocarbons have been recognized in the fluid inclusions in ore minerals collected from the Changkeng deposit. The hydrocarbons are composed mainly of saturated alkanes C1-4 and unsaturated alkenes C2-4 and aromatic hydrocarbons, in which the alkanes are predominant, while the contents of alkenes and aromatic hydrocarbons are very low. The Σalka/Σalke ratio of most samples is higher than 100, suggesting that those hydrocarbons are mainly generated by pyrolysis of kerogens in sedimentary rocks caused by water-rock interactions at medium-low temperatures, and the metallogenic processes might have not been affected by magmatic activity. A thermodynamic calculation shows that the light hydrocarbons have reached chemical equilibrium at temperatures higher than 200?C, and they may have been generated in the deep part of sedimentary basins (e.g., the Sanzhou basin) and then be transported by ore-forming fluids to a shallow position of the basin via a long distance. Most of the organic gases are generated by pyrolysis of the type II kerogens (kukersite) in sedimentary host rocks, only a few by microorganism activity. The compositions and various parameters of light hydrocarbons in gold ores are quite similar to those in silver ores, suggesting that the gold and silver ores may have similar metallogenic processes. Based on the compositions of organic gases in fluid inclusions, the authors infer that the Changkeng deposit may be of a tectonic setting of continental rift. The results of this study support from one aspect the authors' opinion that the Changkeng deposit is not formed by meteoric water convection, and that its genesis has a close relationship with the evolution of the Sanzhou basin, so

  5. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    International Nuclear Information System (INIS)

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle–antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  6. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreira dos Santos, Margarida, E-mail: margarida.santos@fct.unl.pt; Queiroz, Margarida Joao; Baptista, Pedro V. [Universidade Nova de Lisboa, CIGMH, Departamento Ciencias da Vida, Faculdade de Ciencias e Tecnologia (Portugal)

    2012-05-15

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 {+-} 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a {beta}-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  7. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    Science.gov (United States)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-01-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with <3 % NaCl equivalent salinity and with a magmatic source of sulfur (-1 to -2 ‰ δ34Swater). Metal was mainly precipitated at the beginning of vein formation (episode 1) due to a combination of boiling at ˜600 to 800 m below the paleowater table, and associated mixing/cooling processes, as evidenced by sulfide-rich bands showing crustiform-colloform quartz, adularia, and chlorite-smectite banding. During episodes 2 and 3, metal contents progressively decrease during continuing boiling conditions, and veins were filled by quartz and calcite during waning stages of the hydrothermal system, and the influx of bicarbonate waters (-6 to -8.5 ‰ δ18Owater). Hydrothermal alteration is characterized by proximal illite, adularia, and silica zone with chlorite and minor epidote, intermediate interlayered illite-smectite and a distal chlorite halo. This assemblage is in agreement with

  8. Static and dynamic stresses

    DEFF Research Database (Denmark)

    Tishin, A.M.; Spichkin, Yu.I.; Bohr, Jakob

    1999-01-01

    In this chapter we shall consider the properties of lanthanide metals, their alloys and compounds which can be studied using static and alternating mechanical stresses. The main attention will be paid to the effects related to magnetoelastic interactions. These interactions in magnetic materials...... can display themselves in static magnetostriction deformations (this effect is not considered here) and in the changing of the magnetic state under mechanical stress. The latter causes variation of the magnetic phase transition temperatures, magnetization and magnetic structures, and leads to the...

  9. Electrical properties of thin-film structures formed by pulsed laser deposition of Au, Ag, Cu, Pd, Pt, W, Zr metals on n-6H-SiC crystal

    International Nuclear Information System (INIS)

    Diode structures with ideality factors of 1.28-2.14 and potential barriers from 0.58 to 0.62 eV on the semiconductor side were formed by pulsed laser deposition of Au, Ag, Cu, Pd, Pt, W, and Zr metal films on n-6H-SiC crystal without epitaxial layer preparation. A high density of surface acceptor and donor states was formed at the metal-semiconductor interface during deposition of the laser-induced atomic flux, which violated the correlation between the potential barrier height and metal work function. The barrier heights determined from characteristic currents and capacitance measurements were in quite good agreement. For the used low-resistance semiconductor and contact elements, the sizes of majority carrier (electron) depletion regions were determined as 26-60 nm.

  10. DFT study of Hg adsorption on M-substituted Pd(1 1 1) and PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces

    Science.gov (United States)

    Wang, Jiancheng; Yu, Huafeng; Geng, Lu; Liu, Jianwen; Han, Lina; Chang, Liping; Feng, Gang; Ling, Lixia

    2015-11-01

    The adsorption of Hgn (n = 1-3) on the Au-, Ag-, Cu-substituted Pd(1 1 1) surfaces as well as the PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces has been investigated using spin-polarized density functional theory calculations. It is found that M-substituted Pd(1 1 1) surfaces show as good Hg adsorption capacity as the perfect Pd(1 1 1) at low Hg coverage, while the Hg adsorption capacity is only slightly weakened at high Hg coverage. On the basis of stepwise adsorption energies analysis, it is concluded that M-substituted Pd(1 1 1) surfaces can contribute to the binding of Hg atom on the surfaces at high Hg coverage. The electronic properties of the second metal atoms are the main factor contributes to the Hg adsorption capacity. Gas phase Pd2 shows better Hg adsorption capacity than Pd2/γ-Al2O3, while PdM/γ-Al2O3 can adsorb Hg more efficiently than bare PdM clusters. It suggests that the γ-Al2O3 support can enhance the activity of PdM for Hg adsorption and reduces the activity of Pd2. It is also found that Pd is the main active composition responsible for the interaction of mercury with the surface for PdM/γ-Al2O3 sorbent. Taking Hg adsorption capacity and economic costs into account, Cu addition is a comparatively good candidate for Hg capture.

  11. High strain in polycrystalline Ni{sub 48.8}Mn{sub 31.4}Ga{sub 19.8} Heusler alloys under overlapped static and oscillating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Montanher, D. Z.; Pereira, J. R. D.; Cótica, L. F.; Santos, I. A. [Department of Physics, State University of Maringá, Av. Colombo 5790, Maringá - PR 87020-900 (Brazil); Gotardo, R. A. M. [Technological Federal University of Paraná, Av. Alberto Carazzai 1640, Cornélio Procópio - PR 86300-000 (Brazil); Viana, D. S. F.; Garcia, D.; Eiras, J. A. [Department of Physics, Federal University of São Carlos, Rod. Washington Luiz, Km 235, São Carlos - SP 13565-905 (Brazil)

    2014-09-21

    Martensitic polycrystalline Ni{sub 48.8}Mn{sub 31.4}Ga{sub 19.8} Heusler alloys, with a stacking period of 14 atomic planes at room temperature, were innovatively processed by combining high-energy ball milling and powder metallurgy. Bulk samples were mechanically coupled to a piezoelectric material in a parallel configuration, and the mechanical deformation of the studied system due to the twin's variant motion was investigated under overlapped static and oscillating magnetic fields. A reversible and high mechanical deformation is observed when the frequency of the oscillating magnetic field is tuned with the natural vibration frequency of this system. In this condition, a linear deformation as a function of the static magnetic field amplitude occurs in the ±4 kOe range, and a mechanical deformation of 2% at 10 kOe is observed.

  12. Role of pH in the synthesis of 3-aminopropyl trimethoxysilane stabilized colloidal gold/silver and their alloy sols and their application to catalysis

    International Nuclear Information System (INIS)

    Research highlights: → Synthesis of nano-alloy dispersions of Au and Ag in aminosilicate sol. → pH conditions on chemical stability of Au, Ag and their alloy sols were optimized. → The stable alloy sols catalyze the reduction of 4-nitrophenol to 4-aminophenol. → Catalytic rate constants were evaluated from UV-visible spectroscopy. - Abstract: A general method for the synthesis of nano-alloy dispersions of noble metals like Au and Ag in organically modified aminosilicate sol is presented with an emphasis on the influence of pH on the sol stability. The alloys of Au-Ag were synthesized by co-reduction of solutions of gold and silver salts using borohydride as the reducing agent at a suitable pH in the medium containing 3-aminopropyltrimethoxysilane (APS) stabilizer. Organosilanes with amine functional group have multiple roles in the formation of stable sols such as the formation of siloxane network structures by hydrolysis and condensation and the interaction of amino group with metal ions in solution electrostatically. Mono metal and alloy sols were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy. The stable alloy sols were found to catalyze the chemical reduction of 4-nitrophenol to 4-aminophenol and the catalytic rate constants were evaluated from UV-vis spectroscopy.

  13. Role of pH in the synthesis of 3-aminopropyl trimethoxysilane stabilized colloidal gold/silver and their alloy sols and their application to catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Harish, S.; Sabarinathan, R. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India); Joseph, James, E-mail: jameskavalam@yahoo.com [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India); Phani, K.L.N. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2011-05-16

    Research highlights: {yields} Synthesis of nano-alloy dispersions of Au and Ag in aminosilicate sol. {yields} pH conditions on chemical stability of Au, Ag and their alloy sols were optimized. {yields} The stable alloy sols catalyze the reduction of 4-nitrophenol to 4-aminophenol. {yields} Catalytic rate constants were evaluated from UV-visible spectroscopy. - Abstract: A general method for the synthesis of nano-alloy dispersions of noble metals like Au and Ag in organically modified aminosilicate sol is presented with an emphasis on the influence of pH on the sol stability. The alloys of Au-Ag were synthesized by co-reduction of solutions of gold and silver salts using borohydride as the reducing agent at a suitable pH in the medium containing 3-aminopropyltrimethoxysilane (APS) stabilizer. Organosilanes with amine functional group have multiple roles in the formation of stable sols such as the formation of siloxane network structures by hydrolysis and condensation and the interaction of amino group with metal ions in solution electrostatically. Mono metal and alloy sols were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy. The stable alloy sols were found to catalyze the chemical reduction of 4-nitrophenol to 4-aminophenol and the catalytic rate constants were evaluated from UV-vis spectroscopy.

  14. Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Amanda; Zhao, Hongbin; Hopkins, Scott

    2014-09-30

    This report summarizes the work completed under the U.S. Department of Energy Project Award No.: DE-FE0001181 titled “Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods.” The project started in October 1, 2009 and was finished September 30, 2014. Pall Corporation worked with Cornell University to sputter and test palladium-based ternary alloys onto silicon wafers to examine many alloys at once. With the specialized equipment at Georgia Institute of Technology that analyzed the wafers for adsorbed carbon and sulfur species six compositions were identified to have resistance to carbon and sulfur species. These compositions were deposited on Pall AccuSep® supports by Colorado School of Mines and then tested in simulated synthetic coal gas at the Pall Corporation. Two of the six alloys were chosen for further investigations based on their performance. Alloy reproducibility and long-term testing of PdAuAg and PdZrAu provided insight to the ability to manufacture these compositions for testing. PdAuAg is the most promising alloy found in this work based on the fabrication reproducibility and resistance to carbon and sulfur. Although PdZrAu had great initial resistance to carbon and sulfur species, the alloy composition has a very narrow range that hindered testing reproducibility.

  15. Effect of thermal processing parameters on static globularization kinetics of TC17 alloy%热工艺参数对TC17合金静态球化动力学的影响

    Institute of Scientific and Technical Information of China (English)

    孙新; 曾卫东; 张志金; 贾志强; 徐建伟

    2015-01-01

    对TC17合金在820和860℃下进行等温锻造,随后在相同温度下进行热处理10 min~8 h,利用定量金相法研究变形量、热处理温度等工艺参数对片状α相静态球化的影响规律。结果表明:随着变形量的增加,在随后热处理过程中片状α相更容易发生晶界分离而形成球化组织,球化速率明显提高。温度影响扩散过程,对静态球化有促进作用,且在应变较低时影响更为明显。在球化率随热处理时间增大的同时,球化速率逐渐减小至常值, JMAK方程可以用来描述TC17合金静态球化的规律。%The isothermal compression of TC17 alloy at 820 and 860℃, andsubsequently annealing for 10 min−8 h were conducted, and the effects of deformation degree, annealing temperature and annealing time on static globularization of TC17 titanium alloy were investigated. The results show that the deformation degree greatly influences the boundary splitting, so that the static globularization kinetics ofα phase increases with increasing deformation degrees. As a thermally activated process, the diffusivity of solutes is determined by annealing temperature. Thus, the static globularization can be accelerated by increasing the temperature, especially when the strain is low. Meanwhile, globularization ratio increases while static globularization kinetics decrease to a constant with increasing the annealing time. The JMAK equation can be used to describe the static globularization kinetics.

  16. Template free synthesis of silver-gold alloy nanoparticles and cellular uptake of gold nanoparticles in Chinese Hamster Ovary cell

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Angshuman; Shah, Sunil [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat-390002 (India); Kulkarni, Vijay; Murthy, R.S.R. [G. H. Patel Pharmacy Building, TIFAC-CORE in NDDS, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat-390002 (India); Devi, Surekha [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat-390002 (India)], E-mail: surekha_devi@yahoo.com

    2009-01-15

    Gold-silver alloy nanoparticles were synthesized by simultaneous reduction of varying mole fractions of HAuCl{sub 4} and AgNO{sub 3} by sodium citrate in aqueous solution without using stabilizing agents such as surfactant or polymer. Appearance of single absorption peak in visible spectrum indicated formation of homogeneous gold-silver alloy nanoparticles. Transmission electron micrographs also support formation of alloy nanoparticles rather than core-shell particles. The plasmon absorption bands for Au-Ag nanoparticles show linear bathochromic shift with increasing Au content. No significant change in surface plasmon band was observed on storage of samples at 25 {+-} 2 deg. C for 6 months, indicating stability of the particles. Particle size distribution, zeta-potential and conduction of these colloidal suspensions were measured by dynamic light scattering along with Zetasizer. Gold and Au-Ag alloy nanoparticles exhibited fluorescence at 600 nm and in between 600 and 486 nm respectively depending on alloy composition. Gold nanoparticles were used for cell line study using liposome as a carrier. This liposome entrapped gold nanoparticles showed enhanced uptake by Chinese Hamster Ovary (CHO) cells compared to gold nanoparticles.

  17. 160 Ma of magmatic/hydrothermal and metamorphic activity in the Gällivare area: Re-Os dating of molybdenite and U-Pb dating of titanite from the Aitik Cu-Au-Ag deposit, northern Sweden

    Science.gov (United States)

    Wanhainen, Christina; Billström, Kjell; Martinsson, Olof; Stein, Holly; Nordin, Roger

    2005-12-01

    Host rocks to the Aitik Cu-Au-Ag deposit in northern Sweden are strongly altered and deformed Early Proterozoic mica(-amphibole) schists and gneisses. The deposit is characterised by numerous mineralisation styles, vein and alteration types. Four samples were selected for Re-Os molybdenite dating and 12 samples for U-Pb titanite dating in order to elucidate the magmatic/hydrothermal and metamorphic history following primary ore deposition in the Aitik Cu-Au-Ag deposit. Samples represent dyke, vein and alteration assemblages from the ore zone, hanging wall and footwall to the deposit. Re-Os dating of molybdenite from deformed barite and quartz veins yielded ages of 1,876±10 Ma and 1,848±8 Ma, respectively. A deformed pegmatite dyke yielded a Re-Os age of 1,848±6 Ma, and an undeformed pegmatite dyke an age of 1,728±7 Ma. U-Pb dating of titanite from a diversity of alteration mineral associations defines a range in ages between 1,750 and 1,805 Ma with a peak at ca. 1,780 Ma. The ages obtained, together with previous data, bracket a 160-Ma (1,890-1,730 Ma) time span encompassing several generations of magmatism, prograde to peak metamorphism, and post-peak cooling; events resulting in the redistribution and addition of metals to the deposit. This multi-stage evolution of the Aitik ore body suggests that the deposit was affected by several thermal events that ultimately produced a complex ore body. The Re-Os and U-Pb ages correlate well with published regional Re-Os and U-Pb age clusters, which have been tied to major magmatic, hydrothermal, and metamorphic events. Primary ore deposition at ca. 1,890 Ma in connection with intrusion of Haparanda granitoids was followed by at least four subsequent episodes of metamorphism and magmatism. Early metamorphism at 1,888-1,872 Ma overlapping with Haparanda (1,890-1,880 Ma) and Perthite-monzonite (1,880-1,870 Ma) magmatism clearly affected the Aitik area, as well as late metamorphism and Lina magmatism at 1,810-1,774 Ma and

  18. Observations of exciton-surface plasmon polariton coupling and exciton-phonon coupling in InGaN/GaN quantum wells covered with Au, Ag, and Al films

    Science.gov (United States)

    Estrin, Y.; Rich, D. H.; Keller, S.; DenBaars, S. P.

    2015-07-01

    The coupling of excitons to surface plasmon polaritons (SPPs) and longitudinal optical (LO) phonons in Au-, Ag-, and Al-coated InxGa1-xN/GaN multiple and single quantum wells (SQWs) was studied with time-resolved cathodoluminescence (CL) and CL wavelength imaging techniques. Excitons were generated in the metal-coated SQWs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures which are opaque to laser/light excitation. The Purcell enhancement factor (Fp) at low temperatures was obtained by the direct measurement of changes in the carrier lifetime caused by the SQW excitonSPP coupling. The deposition of thin films of Al, Ag, and Au on an InGaN/GaN QW enabled a comparison of excitonSPP coupling for energy ranges in which the surface plasmon energy is greater than, approximately equal to, and less than the QW excitonic transition energy. We investigated the temperature dependence of the Huang-Rhys factors for exciton-to-LO phonon coupling for the metal-covered and bare samples. CL imaging and spectroscopy with variable excitation densities are used to examine the spatial correlations between CL emission intensity, carrier lifetime, QW excitonic emission energy, and the Huang-Rhys factor, all of which are strongly influenced by local fluctuations in the In composition and formation of InN-rich centers.

  19. Poly (vinyl alcohol)/gum karaya electrospun plasma treated membrane for the removal of nanoparticles (Au, Ag, Pt, CuO and Fe3O4) from aqueous solutions

    International Nuclear Information System (INIS)

    In the present work, nanofibre membranes composed of polyvinyl alcohol (PVA) and a natural gum karaya (GK) hydrocolloid were prepared using electrospinning. The electrospun membranes of PVA/GK were cross-linked with heat treatment and later methane plasma was used to obtain a hydrophobic membrane. The morphology, characterization and adsorption ability of P-NFM was assessed using scanning electron microscopy, UV–vis spectroscopy, ATR-FTIR techniques, water contact angle and ICP-MS analytical methods. The membrane was employed for the extraction of nanoparticles (Ag, Au, Pt, CuO and Fe3O4) from water. The nanoparticle extraction kinetic and adsorption isotherm perform the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption capacities of the membrane for the removal of NPs from water diverge in the order Pt > Au > Ag > CuO > Fe3O4. The high adsorption efficiency for the removal of NPs from water was compared with an untreated membrane. Physisorption, functional group interactions, complexation reactions between metal/metal oxide nanoparticles with various functional groups present in NFM and modified surface properties such as the balance of hydrophilicity/hydrophobicity, surface free energy, and the high surface area of the plasma treated membrane were possible mechanisms of NPs adsorption onto NFM. The regeneration and reusability were tested in five consecutive adsorption/desorption cycles

  20. Poly (vinyl alcohol)/gum karaya electrospun plasma treated membrane for the removal of nanoparticles (Au, Ag, Pt, CuO and Fe{sub 3}O{sub 4}) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Padil, Vinod Vellora Thekkae; Černík, Miroslav, E-mail: miroslav.cernik@tul.cz

    2015-04-28

    In the present work, nanofibre membranes composed of polyvinyl alcohol (PVA) and a natural gum karaya (GK) hydrocolloid were prepared using electrospinning. The electrospun membranes of PVA/GK were cross-linked with heat treatment and later methane plasma was used to obtain a hydrophobic membrane. The morphology, characterization and adsorption ability of P-NFM was assessed using scanning electron microscopy, UV–vis spectroscopy, ATR-FTIR techniques, water contact angle and ICP-MS analytical methods. The membrane was employed for the extraction of nanoparticles (Ag, Au, Pt, CuO and Fe{sub 3}O{sub 4}) from water. The nanoparticle extraction kinetic and adsorption isotherm perform the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption capacities of the membrane for the removal of NPs from water diverge in the order Pt > Au > Ag > CuO > Fe{sub 3}O{sub 4}. The high adsorption efficiency for the removal of NPs from water was compared with an untreated membrane. Physisorption, functional group interactions, complexation reactions between metal/metal oxide nanoparticles with various functional groups present in NFM and modified surface properties such as the balance of hydrophilicity/hydrophobicity, surface free energy, and the high surface area of the plasma treated membrane were possible mechanisms of NPs adsorption onto NFM. The regeneration and reusability were tested in five consecutive adsorption/desorption cycles.

  1. Designer electrode interfaces simultaneously comprising three different metal nanoparticle (Au, Ag, Pd)/carbon microsphere/carbon nanotube composites: progress towards combinatorial electrochemistry.

    Science.gov (United States)

    Dai, Xuan; Wildgoose, Gregory G; Compton, Richard G

    2006-11-01

    In this report gold, silver and palladium metal nanoparticles are separately supported on glassy carbon microspheres (GCM) using bulk electroless deposition techniques to produce three different materials labelled as GCM-Au, GCM-Ag and GCM-Pd respectively. These three materials are then combined together into a composite film on a glassy carbon (GC) electrode surface using multiwalled carbon nanotubes (MWCNTs). The MWCNTs serve to not only mechanically support this composite film as a "binder" but they also help to "wire up" each modified GCM to the underlying substrate. The intelligently designed structure of this electrode interface allows this single modified electrode to simultaneously behave as if it were a macrodisc electrode constructed of gold, silver or palladium, whilst using only a fraction of the equivalent amount of these precious metals. Furthermore this unique structure allows the possibility of combinatorial electrochemistry to be realised using a relatively facile electrode construction which avoids the problems of alloy formation, co-deposition and the formation of bimetallic species. For instance a mixture of several different analytes, which can each only be detected on a different specific substrate, can simultaneously be determined using one electrode in a single voltammetric experiment! Alternatively a substrate could undergo electrocatalytic reactions on one substrate, whilst the products, and hence the progress of this reaction, can be studied at a different substrate simultaneously at the same electrode surface. Proof-of-concept examples are presented herein and the designer electrode interface is shown to produce analytical responses to model target analytes such as hydrazine, bromide and thallium(I) ions that are comparable, if not better, than those obtained at metal macrodisc electrodes and even at other state-of-the-art nanoparticle modified electrodes. PMID:17066193

  2. Creep behaviour of the alloys NiCr22Co12Mo and 10CrMo9 10 under static and cyclic load conditions

    International Nuclear Information System (INIS)

    The creep behaviour of NiCr20Co12Mo is investigated under static strain and at 800deg C, with stresses applied ranging from 105 MPa to 370 MPa. The ferritic steel 10CrMo 9 10 is tested for its creep behaviour under static strain and at the temperatures of 600deg C and 550deg C, with stresses applied between 154 MPa and 326 MPa (at 600deg C), or between 250 MPa and 458 MPa (at 550deg C). The experiments are made to determine the effects of changes in strain on the materials' deformation behaviour, placing emphasis on transient creep and elastic or anelastic response. The mean internal stress is determined from changes in strain. Cyclic creep is analysed as a behaviour directly responding to the pattern of change in strain. Effects of certain strain changes not clarified so far are analysed. The cyclic strain experiments are analysed according to the velocity factor concept. The usual models of creep deformation (theta projection concept) are compared with the model of effective strain, which is based on the fundamental equation of plastic deformation by dislocation motion (Orowan equation). (MM)

  3. [Static metatarsalgia].

    Science.gov (United States)

    Eulry, F

    1997-01-01

    Static metatarsalgia involves pain of non-inflammatory origin in the region of the metatarsal heads. It is caused by a functional disorder or anatomic derangement of the architecture over the ball of the foot, whether congenital or acquired, evident or not. Clinical examination, including of the shoe and of the plantar orthosis, distinguishes five types of anomalies: 1. horizontal malalignment of the metatarsal heads with insufficiency at the first metatarsal-phalangeal joint, dominated by hallux valgus, and involvement of the second metatarsal bone, sometimes favouring Freiberg's disease; 2. vertical malalignment, with a hollow anterior foot, sometimes complicated by Morton's neuroma; 3. a combination of these two anomalies, easily diagnosed but less easily treated; 4. possible enlargement of the first metatarsal-phalangeal joint (hallux rigidus, sesamoid pathology); 5. no patent architectural anomalies, but stress fractures or bone insufficiency fractures of the metatarsals. Only clinical examination can orient complementary strategy and examinations. PMID:9035541

  4. Effect of alloying additions to Ag on thermal conductivity, electrical and mechanical properties of Ag-sheathed Bi-2223 tapes

    International Nuclear Information System (INIS)

    Ag-sheathed Bi-2223 tapes were fabricated by a powder-in-tube technique with different configurations of the inner and outer sheath materials: Ag, Ag-Mg-Ni, Ag-Sb and Ag-Au. Characterization of thermal conductivity at 4.2 K to 100 K showed that the addition of Au decreased the thermal conductivity remarkably. The value at 40 K was 53.8 W/(m K) for AgAu-AgAu tape, five times lower than that of Ag-AgMgNi tape. The addition of Sb reduced AC losses much more than other alloyed element, partly due to its high electrical resistivity at 77 K. The measurement results of the normalized I c dependence on magnetic field of the tapes indicated, however, no conclusive correlation between alloy type and I c performance in field was highlighted. The mechanical property of alloy-sheathed tape was also evaluated. The sequence of the tapes' tensile strength from highest to lowest was: Ag-Mg-Ni, Ag-Sb, Ag-Au, Ag

  5. Electrum, the Gold-Silver Alloy, from the Bulk Scale to the Nanoscale: Synthesis, Properties, and Segregation Rules.

    Science.gov (United States)

    Guisbiers, Grégory; Mendoza-Cruz, Rubén; Bazán-Díaz, Lourdes; Velázquez-Salazar, J Jesús; Mendoza-Perez, Rafael; Robledo-Torres, José Antonio; Rodriguez-Lopez, José-Luis; Montejano-Carrizales, Juan Martín; Whetten, Robert L; José-Yacamán, Miguel

    2016-01-26

    The alloy Au-Ag system is an important noble bimetallic phase, both historically (as "Electrum") and now especially in nanotechnology, as it is applied in catalysis and nanomedicine. To comprehend the structural characteristics and the thermodynamic stability of this alloy, a knowledge of its phase diagram is required that considers explicitly its size and shape (morphology) dependence. However, as the experimental determination remains quite challenging at the nanoscale, theoretical guidance can provide significant advantages. Using a regular solution model within a nanothermodynamic approach to evaluate the size effect on all the parameters (melting temperature, melting enthalpy, and interaction parameters in both phases), the nanophase diagram is predicted. Besides an overall shift downward, there is a "tilting" effect on the solidus-liquidus curves for some particular shapes exposing the (100) and (110) facets (cube, rhombic dodecahedron, and cuboctahedron). The segregation calculation reveals the preferential presence of silver at the surface for all the polyhedral shapes considered, in excellent agreement with the latest transmission electron microscopy observations and energy dispersive spectroscopy analysis. By reviewing the nature of the surface segregated element of different bimetallic nanoalloys, two surface segregation rules, based on the melting temperatures and surface energies, are deduced. Finally, the optical properties of Au-Ag nanoparticles, calculated within the discrete dipole approximation, show the control that can be achieved in the tuning of the local surface plasmon resonance, depending of the alloy content, the chemical ordering, the morphology, the size of the nanoparticle, and the nature of the surrounding environment. PMID:26605557

  6. Quasi-static and dynamic compressive deformation of a bulk nanolayered Ag–Cu eutectic alloy: Macroscopic response and dominant deformation mechanisms

    International Nuclear Information System (INIS)

    Nanostructured multilayered material systems offer an attractive method of increasing material strength. This work examines the response of a bulk eutectic silver–copper material (Ag60Cu40, subscripts indicating atomic percent) which has a hierarchical structure of alternating Ag and Cu layers with thicknesses down to 50 nm. The hierarchical structure consists of two primary arrangements of layers, eutectic colonies of parallel layers, most commonly found at the material interior, and “grains” consisting of alternating Ag and Cu layers which emanate from a central region in a radial pattern, most commonly found at the material exterior surface. We show that the hierarchical structure causes a significant increase in the measured strength response when comparing the Ag60Cu40 response to that of the constituent materials in their bulk nanograined or micrograined form. The deformation mechanisms of this material are studied under compressive loading over the quasi-static and dynamic regime (10−3–103 s−1) with strain between 5% and 50%

  7. Quasi-static and dynamic compressive deformation of a bulk nanolayered Ag–Cu eutectic alloy: Macroscopic response and dominant deformation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kingstedt, O.T., E-mail: kingste1@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street, Urbana, IL 61801 (United States); Eftink, B. [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 West Green Street, Urbana, IL 61801 (United States); Lambros, J. [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street, Urbana, IL 61801 (United States); Robertson, I.M. [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 West Green Street, Urbana, IL 61801 (United States)

    2014-02-10

    Nanostructured multilayered material systems offer an attractive method of increasing material strength. This work examines the response of a bulk eutectic silver–copper material (Ag{sub 60}Cu{sub 40}, subscripts indicating atomic percent) which has a hierarchical structure of alternating Ag and Cu layers with thicknesses down to 50 nm. The hierarchical structure consists of two primary arrangements of layers, eutectic colonies of parallel layers, most commonly found at the material interior, and “grains” consisting of alternating Ag and Cu layers which emanate from a central region in a radial pattern, most commonly found at the material exterior surface. We show that the hierarchical structure causes a significant increase in the measured strength response when comparing the Ag{sub 60}Cu{sub 40} response to that of the constituent materials in their bulk nanograined or micrograined form. The deformation mechanisms of this material are studied under compressive loading over the quasi-static and dynamic regime (10{sup −3}–10{sup 3} s{sup −1}) with strain between 5% and 50%.

  8. Investigation on the Cyclic Response of Superelastic Shape Memory Alloy (SMA Slit Damper Devices Simulated by Quasi-Static Finite Element (FE Analyses

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2014-02-01

    Full Text Available In this paper, the superelastic shape memory alloy (SMA slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE analyses. Although the steel slit dampers conventionally used for aseismic design are able to dissipate a considerable amount of energy generated by the plastic yielding of the base materials, large permanent deformation may occur in the entire structure. After strong seismic events, extra damage repair costs are required to restore the original configuration and to replace defective devices with new ones. Innovative slit dampers fabricated by superelastic SMAs that automatically recover their initial conditions only by the removal of stresses without heat treatment are introduced with a view toward mitigating the problem of permanent deformation. The cyclically tested FE models are calibrated to experimental results for the purpose of predicting accurate behavior. This study also focuses on the material constitutive model that is able to reproduce the inherent behavior of superelastic SMA materials by taking phase transformation between austenite and martensite into consideration. The responses of SMA slit dampers are compared to those of steel slit dampers. Axial stress and strain components are also investigated on the FE models under cyclic loading in an effort to validate the adequacy of FE modeling and then to compare between two slit damper systems. It can be shown that SMA slit dampers exhibit many structural advantages in terms of ultimate strength, moderate energy dissipation and recentering capability.

  9. On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)

    International Nuclear Information System (INIS)

    Low alloyed zirconium sheets (Zr702) have been cold-rolled up to 80% thickness reduction and submitted to various isothermal treatments. The aim was to identify the mechanisms which produce microstructure and texture changes during recrystallization and grain growth. XRD and texture analysis, FEG-SEM with EBSD as well as TEM were used to analyze the various specimens. Three types of substructures were observed in the initial deformed material. Accordingly, the nucleation starts in the most deformed areas and continues in the somewhat less deformed areas, which corresponds to a non oriented nucleation and results in a set of new grains, the size of which is very rapidly stabilized. In the last stage of recrystallization, the grains which have resisted the recrystallization disappear progressively by several mechanisms including in situ recrystallization. Therefore, the texture at the end of the recrystallization resembles the one of the deformed state. Normal grain growth leads to a moderate grain size increase due to the precipitates which slow down the grain boundary motion. This is also the stage where the texture changes due to the size advantage, after recrystallization, of grains in some specific orientations. (orig.)

  10. On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)

    Energy Technology Data Exchange (ETDEWEB)

    Dewobroto, N. [LETAM (Lab. d' Etude des Textures et Application aux Materiaux), Univ. Paul Verlaine, Metz (France); Dept. of Microstructure Physics and Metal Forming, Max Planck Inst. for Iron Research, Duesseldorf (Germany); Bozzolo, N.; Wagner, F. [LETAM (Lab. d' Etude des Textures et Application aux Materiaux), Univ. Paul Verlaine, Metz (France); Barberis, P. [Cezus Research Centre, Ugine (France)

    2006-06-15

    Low alloyed zirconium sheets (Zr702) have been cold-rolled up to 80% thickness reduction and submitted to various isothermal treatments. The aim was to identify the mechanisms which produce microstructure and texture changes during recrystallization and grain growth. XRD and texture analysis, FEG-SEM with EBSD as well as TEM were used to analyze the various specimens. Three types of substructures were observed in the initial deformed material. Accordingly, the nucleation starts in the most deformed areas and continues in the somewhat less deformed areas, which corresponds to a non oriented nucleation and results in a set of new grains, the size of which is very rapidly stabilized. In the last stage of recrystallization, the grains which have resisted the recrystallization disappear progressively by several mechanisms including in situ recrystallization. Therefore, the texture at the end of the recrystallization resembles the one of the deformed state. Normal grain growth leads to a moderate grain size increase due to the precipitates which slow down the grain boundary motion. This is also the stage where the texture changes due to the size advantage, after recrystallization, of grains in some specific orientations. (orig.)

  11. Geochemistry of the metavolcanic rocks in the vicinity of the MacLellan Au-Ag deposit and an evaluation of the tectonic setting of the Lynn Lake greenstone belt, Canada: Evidence for a Paleoproterozoic-aged rifted continental margin

    Science.gov (United States)

    Glendenning, Michael W. P.; Gagnon, Joel E.; Polat, Ali

    2015-09-01

    The Paleoproterozoic (ca. 1900 Ma) Lynn Lake greenstone belt of northern Manitoba, Canada, has been previously characterized as comprising a series of tectonically juxtaposed intra-oceanic-derived metavolcanic rocks. The results of more recent local and regional studies, however, support a significant contribution of continental crust during formation of the metasedimentary, metavolcanic, and intrusive igneous rocks that comprise the majority of the Lynn Lake greenstone belt. The tectonic model previously proposed for the Lynn Lake greenstone belt, however, did not consider the geodynamics of the Lynn Lake greenstone belt in the context of all available data. In this study, we report the results of outcrop mapping and petrographic analysis, as well as major, minor, and trace element geochemical analyses for 54 samples from the Northern terrane, and integrate and compare the results with data from previously published studies. These data are used to recharacterize the metavolcanic rocks and to develop a new geodynamic model for the formation of the Lynn Lake greenstone belt. Ultramafic to intermediate rocks in the vicinity of the MacLellan Au-Ag deposit are characterized primarily by E-MORB-like trace element characteristics and Th-Nb-La systematics, which are interpreted to be the result of a primary, plume-derived melt interacting with continental lithosphere at a thinned (i.e., rifted) continental margin. Similarly, the majority of the mafic to intermediate rocks that comprise the Lynn Lake greenstone belt are characterized by flat to E-MORB-like trace element patterns and Th-Nb-La systematics, which are consistent with mantle plume-derived, contaminated, oceanic continental rift or rifted margin setting rocks. This study suggests that the metavolcanic rocks of the Lynn Lake greenstone belt were derived via rifting between the Superior and Hearne Cratons, which resulted in the formation and growth of the Manikewan Ocean. Alternatively, the metavolcanic rocks

  12. Monetary alloys in Iron Age Armorica (Finistère, France): The singular case of the Osismi tribe

    Science.gov (United States)

    Guerra, M. F.; Abollivier, Ph.

    2016-06-01

    The analysis by PIXE and PAA of 64 coins struck in Iron Age Armorica by the Osismi tribe revealed the use of a different system from the usual Celtic Gaul tri-metallic system. The gold-based alloy (Au-Ag-Cu) firstly issued is debased over time to become a silver-based alloy (Ag-Cu-Sn). Based on the analytical data, two chronological phases were defined and dates of issuing could be ascribed to the coin-types. The presence of Sn and Sb in the alloys and the low contents of Pb were used in the attribution of 9 specimens of unknown origin to the Osismi monetary system. Considerations on the mints supplies could also be provided.

  13. Systematics of hydrothermal alteration at the volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) deposit - implications for ore genesis, structure and exploration in a 1.9 Ga ore district, Fennoscandian Shield, Sweden

    Science.gov (United States)

    Kampmann, Tobias C.; Jansson, Nils J.; Stephens, Michael B.; Majka, Jarosław

    2016-04-01

    The Palaeoproterozoic, volcanic-hosted Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit was mined for base and precious metals during several centuries, until its closure in 1992. The deposit is located in a 1.9 Ga ore district in the Bergslagen lithotectonic unit, Fennoscandian Shield, south-central Sweden. Both the ores and their host rock underwent polyphase ductile deformation, and metamorphism under amphibolite facies and later retrograde conditions at 1.9-1.8 Ga (Svecokarelian orogenic system). This study has the following aims: (i) Classify styles and intensities of alteration in the hydrothermally altered zone at Falun; (ii) identify precursor rocks to hydrothermally altered rocks and their spatial distribution at the deposit; (iii) evaluate the chemical changes resulting from hydrothermal alteration using mass change calculations; and (iv) assess the pre-metamorphic alteration assemblages accounting for the observed metamorphic mineral associations in the altered rocks at Falun. Results will have implications for both the ore-genetic and structural understanding of the deposit, as well as for local and regional exploration. Metamorphic mineral associations in the altered rocks include biotite-quartz-cordierite-(anthophyllite) and, more proximally, quartz-anthophyllite-(biotite-cordierite/almandine), biotite-cordierite-(anthophyllite) and biotite-almandine-(anthophyllite). The proximal hydrothermally altered zone corresponds to intense chlorite-style alteration. Subordinate dolomite or calcite marble, as well as calc-silicate (tremolite, diopside) rocks are also present at the deposit. Metavolcanic rocks around the deposit are unaltered, weakly sericitized or sodic-altered. Immobile-element (e.g. Zr, TiO2, Al2O3, REE) systematics of the silicate-rich samples at and around the deposit suggest that the precursors to the hydrothermally altered rocks at Falun were predominantly rhyolitic in composition, dacitic rocks being subordinate and mafic-intermediate rocks

  14. 纳米金银材料在比色检测汞中的应用%The Application of Au-Ag Nanomaterials in the Colorimetric Detection of Mercury

    Institute of Scientific and Technical Information of China (English)

    李红红; 陈兴国

    2012-01-01

    It is very important to develop accurate methods for the determination of trace mercury due to its extremely hazardous and bioconcentration effect on human health and the environment. The conventional detection methods for Hg( II ) , such as Atomic Spectrometry, Inductively Coupled Plasma-Mass Spectrometry, Electrochemical Analysis and Spectrophotometry, require complex sample preparation, expensive instruments, and lengthy analysis, which cannot meet the needs of the actual analysis. The colorimetric method has been widely applied for detecting Hg( JJ ) , but the sensitivity and selectivity are still difficult to measure trace Hg( TJ ) in acomplex matrix. In recent years, nanomaterials of gold ( Au) or silver ( Ag) have attracted the attention of many researchers in the application of colorimetric detection for Hg( II ) because of their unique surface plasmon resonance, and many new methods have been successfully applied to detecting trace Hg( E ) in actual samples. The main colorimetric detection mechanism of Au/Ag nanomaterials is based on the fact that Hg( II ) could cause the aggregation/redispersion or the redox reaction, which induces a color change in the solution. This method has been applied successfully to water samples, however, large interferences exist for other kinds of samples. In this paper, the theory and research progress of Au and Ag nanomaterials in the colorimetric detection of Hg( II ) are reviewed. This is a new direction for establishing a simple, rapid, highly sensitive and highly selective colorimetric detection method for trace Hg( H ) measurements in complex samples in the future.%汞具有生物富集性和剧毒性,对人体健康和环境产生严重的危害和影响,因此开发准确测定样品中微量汞的方法具有重要的实际意义.原子光谱法、电感耦合等离子体质谱法、电化学分析法、分光光度法等测定Hg(Ⅱ)的传统方法,由于存在样品预处理过程复杂、仪器昂贵、分析周

  15. Statics with MATLAB

    CERN Document Server

    Marghitu, Dan B; Madsen, Nels H

    2013-01-01

    Engineering mechanics involves the development of mathematical models of the physical world. Statics addresses the forces acting on and in mechanical objects and systems. Statics with MATLAB®  develops an understanding of the mechanical behavior of complex engineering structures and components using MATLAB®  to execute numerical calculations and to facilitate analytical calculations.   MATLAB® is presented and introduced as a highly convenient tool to solve problems for theory and applications in statics. Included are example problems to demonstrate the MATLAB® syntax and to also introduce specific functions dealing with statics. These explanations are reinforced through figures generated with MATLAB® and the extra material available online which includes the special functions described. This detailed introduction and application of MATLAB® to the field of statics makes Statics with MATLAB® a useful tool for instruction as well as self study,  highlighting the use of symbolic MATLAB® for both theo...

  16. Static electromagnetic frequency changers

    CERN Document Server

    Rozhanskii, L L

    1963-01-01

    Static Electromagnetic Frequency Changers is about the theory, design, construction, and applications of static electromagnetic frequency changers, devices that used for multiplication or division of alternating current frequency. It is originally published in the Russian language. This book is organized into five chapters. The first three chapters introduce the readers to the principles of operation, the construction, and the potential applications of static electromagnetic frequency changers and to the principles of their design. The two concluding chapters use some hitherto unpublished work

  17. Static-static-light baryonic potentials

    OpenAIRE

    Najjar, Johannes; Bali, Gunnar

    2009-01-01

    We determine doubly heavy baryonic potentials as a function of the distance between the two static sources, coupled to a light relativistic quark, for different quantum numbers. We use the variational method to compute the ground state and the first two excitations. These can be used as an input to nonrelativistic models or to NRQCD calculations of properties of doubly heavy baryons. We compare our findings with a factorization model. We employ all-to-all propagator methods, improved by an ad...

  18. Einstein's static universe

    CERN Document Server

    Soares, Domingos Savio

    2012-01-01

    Einstein's static model is the first relativistic cosmological model. The model is static, finite and of spherical spatial symmetry. I use the solution of Einstein's field equations in a homogeneous and isotropic universe -- Friedmann's equation -- to calculate the radius of curvature of the model (also known as "Einstein's universe"). Furthermore, I show, using a Newtonian analogy, the model's mostly known feature, namely, its instability under small perturbations on the state of equilibrium.

  19. Radiation effects on metals, alloys and cement

    International Nuclear Information System (INIS)

    High - energy particle irradiation of materials brings as a consequence changes in their atomic structures that alter the electrical, magnetic and mechanical properties which are the most important characteristics for practical applications of metals and alloys. A review is made on experimental results of in-pile (IEA-RI reactor) and CV-28 cyclotron irradiated materials. Resistivity measurements on CuPd and FeNi alloys showed different behaviour during fast neutron irradiation. While CuPd had almost coincidental relaxation curves, FeNi presented a distinguishable short and long-range ordering with the critical order-disorder temperature at 5150C. Vacancy supersaturation curves of FeNiSi (49-49-2 at %), FeNiCr (49-95-49, 95-0,1 at. %), FeNiMo (50-50 at.% + 50 ppm) and pure FeNi (50-50 at.%), determined by means of the Magnetic After Effect are presented as an effective pre-selection method of nuclear materials before the destructive stage of void formation and swelling. A displacement of damage peak from 480 to 500 and 5700C was detected on pure AISI 321 stainless steel and with 0,05 wt.% and 0,10 wt.% of Nb additions by means of resistivity and micro-hardness. Ultrasound techniques applied to fast neutron irradiated portland cement paste (fluence 7,2 x 1018 n/cm2) showed a 24% decrease in its dynamic elasticity modulus. Helium diffusion on Au, Ag and Al foils irradiated in cyclotron was studied, suggesting a vacancy mechanism for single He atom diffusion. Embrittlement by Alpha particle implantation in cyclotron to simulate in-pile (n,α) reaction-was measured by high temperature creep on AISI 316 stainles steel. (author)

  20. Energy conversion statics

    CERN Document Server

    Messerle, H K; Declaris, Nicholas

    2013-01-01

    Energy Conversion Statics deals with equilibrium situations and processes linking equilibrium states. A development of the basic theory of energy conversion statics and its applications is presented. In the applications the emphasis is on processes involving electrical energy. The text commences by introducing the general concept of energy with a survey of primary and secondary energy forms, their availability, and use. The second chapter presents the basic laws of energy conversion. Four postulates defining the overall range of applicability of the general theory are set out, demonstrating th

  1. Effect of stress level on static young's modulus of certain structural materials

    International Nuclear Information System (INIS)

    Certain steels, titanium and aluminium alloys have been studied for their dynamic and static Young moduli. It is shown that a stress rise in materials to the level of microplastic strain realization results in a significant reduction of the static modulus of elasticity in the materials studied

  2. Explosions and static electricity

    DEFF Research Database (Denmark)

    Jonassen, Niels M

    1995-01-01

    The paper deals with the problem of electrostatic discharges as causes of ignition of vapor/gas and dust/gas mixtures. A series of examples of static-caused explosions will be discussed. The concepts of explosion limits, the incendiveness of various discharge types and safe voltages are explained...

  3. Static Transition Compression

    DEFF Research Database (Denmark)

    Danvy, Olivier; Damian, Daniel

    2001-01-01

    compositional and context-sensitive specification that provably gives rise to no static chains of jumps, no redundant labels, and no unused labels. It is defined with one inference rule per syntactic construct and operates in linear time and space on the size of the source program (indeed it operates in one...

  4. Modelling static impurities

    OpenAIRE

    Correia, Sebastiao; Polonyi, Janos; Richert, Jean

    2000-01-01

    A simple model is presented for the calculation of the quenched average over impurities which are rendered static by setting their mass equal to infinity. The path integral formalism of the second quantized theory contains annealed averages only. The similarity with the Gaussian quenched potential model is discussed.

  5. Small angle neutron scattering in invar alloys

    International Nuclear Information System (INIS)

    Some results of low angle neutron scattering on 70-30 and 65-35 FeNi alloys are presented showing the existence of chemical small clusters associated with a magnetization inhomogeneity. A noticeable result is the appearance of a pseudo-periodical magnetization static fluctuation in a 65-35 FeNi alloy after irradiation with 2 MeV electrons

  6. Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

    Directory of Open Access Journals (Sweden)

    Feng Lili

    2011-01-01

    Full Text Available Abstract In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future.

  7. Static analysis for blinding

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Rosenkilde; Nielson, Hanne Riis

    2006-01-01

    operation blinding. In this paper we study the theoretical foundations for one of the successful approaches to validating cryptographic protocols and we extend it to handle the blinding primitive. Our static analysis approach is based on Flow Logic; this gives us a clean separation between the specification...... of the analysis and its realisation in an automatic tool. We concentrate on the former in the present paper and provide the semantic foundation for our analysis of protocols using blinding - also in the presence of malicious attackers....

  8. The static baryon potential

    International Nuclear Information System (INIS)

    Using state of the art lattice techniques we investigate the static baryon potential. We employ the multi-hit procedure for the time links and a variational approach to determine the ground state with sufficient accuracy that, for distances up to ∼ 1.2 fm, we can distinguish the Y- and Δ- Ansaetze for the baryonic Wilson area law. Our analysis shows that the Δ-Ansatz is favoured. This result is also supported by the gauge-invariant nucleon wave function which we measure for the first time

  9. Static and dynamic stresses

    DEFF Research Database (Denmark)

    Tishin, A.M.; Spichkin, Yu.I.; Bohr, Jakob

    1999-01-01

    can display themselves in static magnetostriction deformations (this effect is not considered here) and in the changing of the magnetic state under mechanical stress. The latter causes variation of the magnetic phase transition temperatures, magnetization and magnetic structures, and leads...... to the appearance of anomalies in elastic constants, as well as to additional damping of sound oscillations in the lanthanide materials. The importance of understanding the nature of magnetoelastic interactions and related effects arises from the scientific desire to gather a better knowledge of magnetism, as well...

  10. Development of a high temperature static strain gage system

    International Nuclear Information System (INIS)

    The objective of this program is to develop electrical resistance strain gages which will permit the measurement of static strains on nickel and cobalt superalloy parts inside gas turbine engines running on a test stand. The specific goal is to develop a complete system able to make strain measurements up to plus or minus 2000 mu strain with a total error of no more than plus or minus 10 percent over a 50 hour period at 1250 K. The initial part of this work consisted of a strain gage alloy development effort in which a variety of alloys were evaluated after being prepared by drop-casting or splat cooling

  11. Density functional theory study of the effects of alloying additions on sulfur adsorption on nickel surfaces

    International Nuclear Information System (INIS)

    Highlights: ► We study sulfur adsorption on metal doped and undoped Ni surfaces. ► Hybridization of Ni-3d and S-3p states plays the most important role in the formation of Ni-S bonds. ► Au, Ag, Al, Bi, Cd, Sb, Sn, Zn additions can significantly increase sulfur tolerance of Ni. ► Sn, Sb, and Bi alloying additions have the strongest effects on sulfur adsorption. - Abstract: Reactions of hydrogen sulfide (H2S) with Nickel/Ytrria-doped zirconia (Ni/YDZ) anode materials might cause degradation of the performance of solid oxide fuel cells when S containing fuels are used. In this paper, we employ density functional theory to investigate S adsorption on metal (M)-doped and undoped Ni(0 0 1) and Ni(1 1 1) surfaces. Based on the performed calculations, we analyze the effects of 12 alloying additions (Ag, Au, Al, Bi, Cd, Co, Cu, Fe, Sn, Sb, V, and Zn) on the temperature of transition between clean (S atoms do not adsorb on the surfaces) and contaminated (S atoms can adsorb on the surfaces spontaneously) M-doped Ni surfaces for different concentrations of H2S in the fuel. Predicted results are consistent with many experimental studies relevant to S poisoning of both Ni/YDZ and M-doped Ni/YDZ anode materials. This study is important to understand S poisoning phenomena and to develop new S tolerant anode materials.

  12. Quantum singularities in static and conformally static space-times

    CERN Document Server

    Konkowski, D A; 10.1142/S0217751X11054334

    2011-01-01

    The definition of quantum singularity is extended from static space-times to conformally static space-times. After the usual definitions of classical and quantum singularities are reviewed, examples of quantum singularities in static space-times are given. These include asymptotically power-law space-times, space-times with diverging higher-order differential invariants, and a space-time with a 2-sphere singularity. The theory behind quantum singularities in conformally static space-times is followed by an example, a Friedmann-Robertson-Walker space-time with cosmic string. The paper concludes by discussing areas of future research.

  13. 西藏玉龙铜矿铜钼混合浮选-强化金银回收工艺技术研究%Research on Cu-Mo bulk flotation-strengthening collecting Au & Ag technology about Yulong copper mine, Tibet

    Institute of Scientific and Technical Information of China (English)

    唐顺昌; 王立刚

    2014-01-01

    With high contain of secondary copper ,much mica and clay ,the ore property is very complex .On the other hand ,there is very low grade of gold and silver ,and the precious metal is hard to be collected in concentrate .The good flotation index was achieved with highly selective collector BK402 .And also the gold and silver were forced to be collected in final flotation production .Based on research ,the pilot test was carried out by Cu‐Mo bulk flotation‐strengthening collecting Au &Ag technology with one roughing‐two scavenging‐two cleaning .The average index of pilot test is:the concentrate with the grade and recovery of copper is 29 .84% and 89 .38% separately ,the grade and recovery of molybdenum is 0 .51% and 78 .86% .and also there is gold with 1 .26g/t and silver with 58 .87g/t ,the recovery of gold and silver is 29.30% and 56 .93% respectively .%西藏玉龙铜矿I号矿体硫化矿含次生铜较高、含有较多的云母及黏土类矿物,矿石性质复杂;同时,原矿含金、银品位较低,难以使贵金属在精矿中富集。通过使用高效选择性捕收剂BK402,强化金、银的捕收,取得了较好的选矿指标。在小型试验的基础上,进行了选矿扩大连续试验,采用铜钼混合浮选‐强化金银回收工艺流程,经一粗两扫两精作业,扩大试验获得平均班指标为:铜钼混合精矿铜品位29.84%,铜回收率89.38%;钼品位0.51%,钼回收率78.86%;铜钼混合精矿中含 Au 1.26g/t ,含 Ag 58.87g/t ,Au的回收率为29.30%,Ag的回收率为56.93%。

  14. Hydroxyl capped silver-gold alloy nanoparticles: characterization and their combination effect with different antibiotics against Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Katayon Bahrami

    2014-04-01

    Full Text Available   Objective(s: Metal nanoparticles (NPs offer a wide variety of potential applications in pharmaceutical sciences due to the unique advances in nanotechnology research. In this work, bimetal Ag-Au alloy NPs were prepared and their combinations with other antibiotics were tested against Staphylococcus aureus .   Materials and Methods: Firstly, Ag-Au alloy NPs with Au/Ag molar ratio of 1:1 was fabricated and was purified by agarose gel electrophoresis system. The morphology and size of the purified NPs were confirmed by transmission electron microscopy. Chemical composition and surface chemistry of these NPs were studied with atomic absorption spectophotometry and Fourier transforms infrared spectroscopy, respectively. The size of purified Ag-Au alloy NPs was less than 200 nm. Also the presence of organic compounds with a hydroxyl residue was detected on the surface of these purified NPs. In next step the effect of purified Ag-Au alloy NPs on the antibacterial activity of different antibiotics was evaluated at sub-inhibitory content (5 μg/disk using disk diffusion method against S. aureus. Ag NPs and Au NPs were also tested at same content (5 μg using mentioned method. Results: The most enhancing effect of Ag-Au alloy NPs was observed for penicillin G and piperacillin. No enhancing effects on the antibacterial activity of different antibiotics were observed at 5 μg/disk for the mono-metal nanoparticles (Ag NPs and Au NPs against S. aureus. Conclusion: These results signify that the Ag-Au alloy NPs potentiates the antimicrobial action of certain antibiotics suggesting a possible utilization of this nano material in combination therapy against resistant S. aureus.

  15. Magnetic static response functions

    International Nuclear Information System (INIS)

    The response of a normally non-magnetic material to an external static magnetic field can be monitored by many different magnetic response functions. A general scheme to supply a corresponding theoretical description is presented that is based on the relativistic Korringa-Kohn-Rostoker Green function method of band structure calculations, and for that reason has many appealing features. First of all, it treats all spin as well as orbital contributions to the induced magnetization on the same footing, accounting in particular for all relativistic influences. Furthermore, it is extremely flexible and applicable in principle to any kind of system. Finally, a formulation for any response function can be worked out on this platform in a rather straightforward way. This is demonstrated together with corresponding applications for the magnetic form factor, the magnetic susceptibility and the Knight shift. In addition, a description of the so-called field-induced magnetic circular dichroism in x-ray absorption will be presented. In particular, it is shown that this new magneto-optical effect supplies a rather unique probe, giving information separately on the spin and orbital susceptibility in an element-resolved way

  16. Static recrystallization behavior of AEREX350 superalloy

    International Nuclear Information System (INIS)

    Research highlights: → The static recrystallization behavior of a complex superalloy, AEREX 350, is investigated. → It is found that this alloy resists recrystallization to very high temperatures (1025 deg. C, 0.81Tm). → TEM investigation showed evidence of grain boundary pinning by the Widmanstaetten η platelets. → Recrystallization of the AEREX 350 superalloy proceeds by the discontinuous precipitation of the η particles behind the moving boundary. - Abstract: The recrystallization behavior of a commercial nickel-cobalt base superalloy, AEREX 350, is investigated by means of hardness test, X-ray diffraction, and microscopy. It is found that the alloy resists recrystallization up to a high temperature of 1025 deg. C. Recrystallized grains are readily formed at grain boundaries below this temperature; however, the growth of these new grains is inhibited by Widmanstaetten η particles having coherent facets with the nickel matrix (γ). The passage of the recrystallization front results in coherency loss and consequently dissolution of the η platelets. Recrystallization proceeds with a discontinuous precipitation of the η phase behind the moving boundary.

  17. Statics and Mechanics of Structures

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    The statics and mechanics of structures form a core aspect of civil engineering. This book provides an introduction to the subject, starting from classic hand-calculation types of analysis and gradually advancing to a systematic form suitable for computer implementation. It starts with statically...

  18. Properties of Broezel static probe

    Science.gov (United States)

    Gašparovič, Peter; Semrád, Karol; Cúttová, Miroslava

    2016-03-01

    The properties of flat static probe designed by Broezel and used in sailplanes are investigated for its planned use in low speed tunnel. Both the numerical CFD model and experiment in low speed wind tunnel confirm yaw insensitivity of the static pressure measured by the probe. The results indicate that the probe is sufficiently accurate for its planned use in wind tunnel measurements.

  19. Brendle's inequality on static manifolds

    CERN Document Server

    Wang, Xiaodong

    2016-01-01

    We generalize Brendle's geometric inequality considered in \\cite{B} to static manifolds. The inequality bounds the integral of inverse mean curvature of an embedded mean-convex hypersurface by geometric data of the horizon. As a consequence, we obtain a reverse Penrose inequality on static asymptotically locally hyperbolic manifolds in the spirit of Chru\\'{s}ciel and Simon \\cite{CS}.

  20. Static multipole deformations in nuclei

    International Nuclear Information System (INIS)

    The physics of static multipole deformations in nuclei is reviewed. Nuclear static moments result from the delicate balance between the vibronic Jahn-Teller interaction (particle-vibration coupling) and the residual interaction (pairing force). Examples of various permanent nuclear deformations are discussed

  1. Model Checking as Static Analysis

    DEFF Research Database (Denmark)

    Zhang, Fuyuan

    properties which can predict safe approximations to program behaviors. In this thesis, we have developed several static analysis based techniques to solve model checking problems, aiming at showing the link between static analysis and model checking. We focus on logical approaches to static analysis......Both model checking and static analysis are prominent approaches to detecting software errors. Model Checking is a successful formal method for verifying properties specified in temporal logics with respect to transition systems. Static analysis is also a powerful method for validating program...... multi-valued setting, and we therefore obtain a multivalued analysis for temporal properties specied by CTL formulas. In particular, we have shown that the three-valued CTL model checking problem over Kripke modal transition systems can be exactly encoded in three-valued ALFP. Last, we come back to two...

  2. Corrosion of aluminum alloys as a function of alloy composition

    International Nuclear Information System (INIS)

    A study was initiated which included nineteen aluminum alloys. Tests were conducted in high purity water at 3600C and flow tests (approx. 20 ft/sec) in reactor process water at 1300C (TF-18 loop tests). High-silicon alloys and AlSi failed completely in the 3600C tests. However, coupling of AlSi to 8001 aluminum suppressed the failure. The alloy compositions containing iron and nickel survived tht 3600C autoclave exposures. Corrosion rates varied widely as a function of alloy composition, but in directions which were predictable from previous high-temperature autoclave experience. In the TF-18 loop flow tests, corrosion penetrations were similar on all of the alloys and on high-purity aluminum after 105 days. However, certain alloys established relatively low linear corrosion rates: Al-0.9 Ni-0.5 Fe-0.1 Zr, Al-1.0 Ni-0.15 Fe-11.5 Si-0.8 Mg, Al-1.2 Ni-1.8 Fe, and Al-7.0 Ni-4.8 Fe. Electrical polarity measurements between AlSi and 8001 alloys in reactor process water at temperatures up to 1500C indicated that AlSi was anodic to 8001 in the static autoclave system above approx. 500C

  3. Silver- and Zirconium-added ternary and quaternary TiAu based high temperature shape memory alloys

    International Nuclear Information System (INIS)

    Low strength in B2 phase, incomplete shape memory effect and high cost of Au are obstacles for the use of Ti–50Au as a high temperature shape memory alloy. We investigated the effects of partial substitution of Ti with Zr and Au with Ag in Ti–Au on phase constitution, phase transformation, and high temperature thermo-mechanical and shape memory properties. Partial substitution of Ti with Zr in Ti–50Au and Ti–40Au–10Ag was found to improve the thermo-mechanical and shape memory effect. However, partial substitution of Au with Ag in Ti–50Au and Ti–50Au–10Zr was found to have negligible effects. Reasons for such different behavior of Zr- and Ag-added Ti–Au alloys are considered. - Highlights: • Au, Ag and Ti, Zr belong to same group. Effects of partial substitution of Au with Ag and Ti with Zr in Ti–Au are investigated. • Zr was found more effective than Ag in improving shape memory and mechanical properties. • Same atomic size of Au and Ag and large size misfit b/w Ti and Zr atoms. • Ag resulted large amount of precipitation in Ti–Au.

  4. Silver- and Zirconium-added ternary and quaternary TiAu based high temperature shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wadood, A., E-mail: abdul.wadood@ist.edu.pk [High Temperature Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Department of Materials Science and Engineering, Institute of Space Technology (IST), Near Rawat Toll Plaza, Islamabad (Pakistan); Yamabe-Mitarai, Y. [High Temperature Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2015-10-15

    Low strength in B2 phase, incomplete shape memory effect and high cost of Au are obstacles for the use of Ti–50Au as a high temperature shape memory alloy. We investigated the effects of partial substitution of Ti with Zr and Au with Ag in Ti–Au on phase constitution, phase transformation, and high temperature thermo-mechanical and shape memory properties. Partial substitution of Ti with Zr in Ti–50Au and Ti–40Au–10Ag was found to improve the thermo-mechanical and shape memory effect. However, partial substitution of Au with Ag in Ti–50Au and Ti–50Au–10Zr was found to have negligible effects. Reasons for such different behavior of Zr- and Ag-added Ti–Au alloys are considered. - Highlights: • Au, Ag and Ti, Zr belong to same group. Effects of partial substitution of Au with Ag and Ti with Zr in Ti–Au are investigated. • Zr was found more effective than Ag in improving shape memory and mechanical properties. • Same atomic size of Au and Ag and large size misfit b/w Ti and Zr atoms. • Ag resulted large amount of precipitation in Ti–Au.

  5. Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays

    Directory of Open Access Journals (Sweden)

    Christoph Rehbock

    2014-09-01

    Full Text Available Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4–400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag+ ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered.

  6. Application of shape memory alloy (SMA) as actuator

    OpenAIRE

    Ľ. Miková; Medvecká - Beňová, S.; M. Kelemen; Trebuňa, F.; Virgala, I.

    2015-01-01

    This paper deals w ith actuators based on shape memory alloys. The testing device has been developed for experimental verification of shape memory alloy actuator testing. Static characteristic shows the hysteresis of this material. Also dynamic properties have been explored through the step response characteristic. Application of the material as actuator in engineering system is shown.

  7. Statics of Historic Masonry Constructions

    CERN Document Server

    Como, Mario

    2013-01-01

    Masonry constructions are the great majority of the buildings in Europe’s historic centres and the most important monuments in its architectural heritage. Given the age of much of these constructions, the demand for safety assessments and restoration projects is pressing and constant. This book aims to help fill this demand presenting a comprehensive new statics of masonry constructions. The book, result of thirty years of research and professional experience, gives the fundamentals of statics of the masonry solid, then applied to the study of statics of arches, piers and vaults. Further, combining engineering and architecture and through an interdisciplinary approach, the book investigates the statical behaviour of many historic monuments, as the Pantheon, the Colosseum,  the domes of S. Maria del Fiore in Florence and of St. Peter in Rome, the Tower of Pisa, the Gothic Cathedrals and the Masonry Buildings under seismic actions.

  8. Statics and mechanics of structures

    CERN Document Server

    Krenk, Steen

    2013-01-01

    The statics and mechanics of structures form a core aspect of civil engineering. This book provides an introduction to the subject, starting from classic hand-calculation types of analysis and gradually advancing to a systematic form suitable for computer implementation. It starts with statically determinate structures in the form of trusses, beams and frames. Instability is discussed in the form of the column problem - both the ideal column and the imperfect column used in actual column design. The theory of statically indeterminate structures is then introduced, and the force and deformation methods are explained and illustrated. An important aspect of the book’s approach is the systematic development of the theory in a form suitable for computer implementation using finite elements. This development is supported by two small computer programs, MiniTruss and MiniFrame, which permit static analysis of trusses and frames, as well as linearized stability analysis. The book’s final section presents related ...

  9. Static Validation of XSL Transformations

    DEFF Research Database (Denmark)

    Møller, Anders; Olesen, Mads Østerby; Schwartzbach, Michael Ignatieff

    2007-01-01

    XSL Transformations (XSLT) is a programming language for defining transformations among XML languages. The structure of these languages is formally described by schemas, for example using DTD or XML Schema, which allows individual documents to be validated. However, existing XSLT tools offer no...... static guarantees that, under the assumption that the input is valid relative to the input schema, the output of the transformation is valid relative to the output schema. We present a validation technique for XSLT based on the XML graph formalism introduced in the static analysis of JWIG Web services...... and XACT XML transformations. Being able to provide static guarantees, we can detect a large class of errors in an XSLT stylesheet at the time it is written instead of later when it has been deployed, and thereby provide benefits similar to those of static type checkers for modern programming...

  10. Static Decoupling in fault detection

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik

    An algebraic approach is given for a design of a static residual weighting factor in connection with fault detection. A complete parameterization is given of the weighting factor which will minimize a given performance index......An algebraic approach is given for a design of a static residual weighting factor in connection with fault detection. A complete parameterization is given of the weighting factor which will minimize a given performance index...

  11. Quasi-Static Hydrodynamic Limits

    Science.gov (United States)

    De Masi, Anna; Olla, Stefano

    2015-12-01

    We consider hydrodynamic limits of interacting particles systems with open boundaries, where the exterior parameters change in a time scale slower than the typical relaxation time scale. The limit deterministic profiles evolve quasi-statically. These limits define rigorously the thermodynamic quasi static transformations also for transitions between non-equilibrium stationary states. We study first the case of the symmetric simple exclusion, where duality can be used, and then we use relative entropy methods to extend to other models like zero range systems. Finally we consider a chain of anharmonic oscillators in contact with a thermal Langevin bath with a temperature gradient and a slowly varying tension applied to one end.

  12. Advanced high temperature static strain sensor development

    Science.gov (United States)

    Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

    1986-01-01

    An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

  13. Counterterms for static Lovelock solutions

    Energy Technology Data Exchange (ETDEWEB)

    Mehdizadeh, M.R. [Shahid Bahonar University, Department of Physics, PO Box 76175, Kerman (Iran, Islamic Republic of); Dehghani, M.H. [Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Zangeneh, M.K. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

    2015-06-15

    In this paper, we introduce the counterterms that remove the non-logarithmic divergences of the action in third order Lovelock gravity for static spacetimes. We do this by defining the cosmological constant in such a way that the asymptotic form of the metric have the same form in Lovelock and Einstein gravities. Thus, we employ the counterterms of Einstein gravity and show that the power law divergences of the action of Lovelock gravity for static spacetimes can be removed by suitable choice of coefficients. We find that the dependence of these coefficients on the dimension in Lovelock gravity is the same as in Einstein gravity. We also introduce the finite energy-momentum tensor and employ these counterterms to calculate the finite action and mass of static black hole solutions of third order Lovelock gravity. Next, we calculate the thermodynamic quantities and show that the entropy calculated through the use of Gibbs-Duhem relation is consistent with the obtained entropy by Wald's formula. Furthermore, we find that in contrast to Einstein gravity in which there exists no uncharged extreme black hole, third order Lovelock gravity can have these kind of black holes. Finally, we investigate the stability of static charged black holes of Lovelock gravity in canonical ensemble and find that small black holes show a phase transition between very small and small black holes, while the large ones are stable. (orig.)

  14. Static Analysis for Systems Biology

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Rosa, D. Schuch da;

    2004-01-01

    This paper shows how static analysis techniques can help understanding biological systems. Based on a simple example we illustrate the outcome of performing three different analyses extracting information of increasing precision. We conclude by reporting on the potential impact and exploitation o...... of these techniques in systems biology....

  15. Counterterms for static Lovelock solutions

    International Nuclear Information System (INIS)

    In this paper, we introduce the counterterms that remove the non-logarithmic divergences of the action in third order Lovelock gravity for static spacetimes. We do this by defining the cosmological constant in such a way that the asymptotic form of the metric have the same form in Lovelock and Einstein gravities. Thus, we employ the counterterms of Einstein gravity and show that the power law divergences of the action of Lovelock gravity for static spacetimes can be removed by suitable choice of coefficients. We find that the dependence of these coefficients on the dimension in Lovelock gravity is the same as in Einstein gravity. We also introduce the finite energy-momentum tensor and employ these counterterms to calculate the finite action and mass of static black hole solutions of third order Lovelock gravity. Next, we calculate the thermodynamic quantities and show that the entropy calculated through the use of Gibbs-Duhem relation is consistent with the obtained entropy by Wald's formula. Furthermore, we find that in contrast to Einstein gravity in which there exists no uncharged extreme black hole, third order Lovelock gravity can have these kind of black holes. Finally, we investigate the stability of static charged black holes of Lovelock gravity in canonical ensemble and find that small black holes show a phase transition between very small and small black holes, while the large ones are stable. (orig.)

  16. Static Behaviour of Bucket Foundations

    DEFF Research Database (Denmark)

    Larsen, Kim André

    . The monopod concept is investigated in this thesis, regarding the static behaviour from loads relevant to offshore wind turbines. The main issue in this concept is the rotational stiffness of the foundation and the combined capacity dominated by moments. The vertical bearing capacity of bucket...

  17. Counterterms for static Lovelock solutions

    Science.gov (United States)

    Mehdizadeh, M. R.; Dehghani, M. H.; Zangeneh, M. Kord

    2015-06-01

    In this paper, we introduce the counterterms that remove the non-logarithmic divergences of the action in third order Lovelock gravity for static spacetimes. We do this by defining the cosmological constant in such a way that the asymptotic form of the metric have the same form in Lovelock and Einstein gravities. Thus, we employ the counterterms of Einstein gravity and show that the power law divergences of the action of Lovelock gravity for static spacetimes can be removed by suitable choice of coefficients. We find that the dependence of these coefficients on the dimension in Lovelock gravity is the same as in Einstein gravity. We also introduce the finite energy-momentum tensor and employ these counterterms to calculate the finite action and mass of static black hole solutions of third order Lovelock gravity. Next, we calculate the thermodynamic quantities and show that the entropy calculated through the use of Gibbs-Duhem relation is consistent with the obtained entropy by Wald's formula. Furthermore, we find that in contrast to Einstein gravity in which there exists no uncharged extreme black hole, third order Lovelock gravity can have these kind of black holes. Finally, we investigate the stability of static charged black holes of Lovelock gravity in canonical ensemble and find that small black holes show a phase transition between very small and small black holes, while the large ones are stable.

  18. FORTRAN Static Source Code Analyzer

    Science.gov (United States)

    Merwarth, P.

    1984-01-01

    FORTRAN Static Source Code Analyzer program, SAP (DEC VAX version), automatically gathers statistics on occurrences of statements and structures within FORTRAN program and provides reports of those statistics. Provisions made for weighting each statistic and provide an overall figure of complexity.

  19. Quasicrystal-reinforced Mg alloys

    International Nuclear Information System (INIS)

    The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg–Zn–Y and Mg–Zn–Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg–Zn–Y alloys, the co-presence of I and Ca2Mg6Zn3 phases by addition of Ca can significantly enhance formability, while in Mg–Zn–Al alloys, the co-presence of the I-phase and Mg2Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg–Zn–Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg–Zn–Al–Sn alloys is attributed to the presence of finely distributed Mg2Sn and I-phase particles embedded in the α-Mg matrix. (review)

  20. Static behaviour of induced seismicity

    Directory of Open Access Journals (Sweden)

    A. Mignan

    2015-12-01

    Full Text Available The standard paradigm to describe seismicity induced by fluid injection is to apply nonlinear diffusion dynamics in a poroelastic medium. I show that the spatiotemporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground, it is not pertinent to the behaviour of induced seismicity. The proposed model is equivalent to the static stress model for tectonic foreshocks generated by the Non-Critical Precursory Accelerating Seismicity Theory. This study hence verifies the explanatory power of this theory outside of its original scope.

  1. Static behaviour of induced seismicity

    CERN Document Server

    Mignan, Arnaud

    2015-01-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply nonlinear diffusion dynamics in a poroelastic medium. I show that the spatiotemporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground, it is not pertinent to the behaviour of induced seismicity. The proposed model is equivalent to the static stress model for tectonic foreshocks generated by the Non- Critical Precursory Accelerating Seismicity Theory. This study hence verifies the explanatory power of this theory outside of its original scope.

  2. Statics of historic masonry constructions

    CERN Document Server

    Como, Mario

    2016-01-01

    This successful book, which is now appearing in its second edition, presents a comprehensive new Statics of Masonry Constructions. Masonry constructions are the great majority of the buildings in Europe’s historic centres and the most important monuments in its architectural heritage. Given the age of these constructions, the demand for safety assessments and restoration projects is pressing and constant. The book you hold in hands contributes to fill this demand. The second edition integrates the original text of the first edition with new developments, widening and revisions, due to recent research studies achievements. The result is a book that gives a complete picture of the behaviour of the Masonry Constructions. First of all, it gives the fundamentals of its Statics, based on the no-tension assumption, and then it develops the Limit Analysis for the Masonry Constructions. In this framework, through an interdisciplinary approach combining Engineering and Architecture, the book also investigates the sta...

  3. Static behaviour of induced seismicity

    OpenAIRE

    Mignan, Arnaud

    2016-01-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply non-linear diffusion dynamics in a poroelastic medium. I show that the spatio-temporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to...

  4. Static behaviour of induced seismicity

    OpenAIRE

    Mignan, A

    2015-01-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply nonlinear diffusion dynamics in a poroelastic medium. I show that the spatiotemporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid ...

  5. Static behaviour of induced seismicity

    OpenAIRE

    Mignan, Arnaud

    2015-01-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply nonlinear diffusion dynamics in a poroelastic medium. I show that the spatiotemporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground...

  6. Size scaling of static friction

    OpenAIRE

    Braun, O. M.; Manini, Nicola; Tosatti, Erio

    2013-01-01

    Sliding friction across a thin soft lubricant film typically occurs by stick-slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick-slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Her...

  7. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...... thermoelastic coefficients and age hardenable low expansion alloys....

  8. High temperature static strain gage development contract, tasks 1 and 2. Interim report

    International Nuclear Information System (INIS)

    Results are presented for the first two tasks to develop resistive strain gage systems for use up to 1250 K on blades and vanes in gas turbine engines under tests. The objective of these two tasks was to further improve and evaluate two static strain gage alloys identified as candidates in a previous program. Improved compositions were not found for either alloy. Further efforts on the Fe-11.9Al-10.6Cr weigth percent alloy were discontinued because of time dependent drift problems at 1250 K in air. When produced as a 6.5 micrometer thick sputtered film, the Pd-13Cr weight percent alloys is not sufficiently stable for this use in air at 1250 K and a protective overcoat system will need to be developed

  9. Effect of Fatigue Crack on Static Strength: 2014-T6, 2024-T4, 6061-T6, 7075-T6 Open-Hole Monobloc Specimens

    Science.gov (United States)

    Nordmark, Glenn E.; Eaton, Ian D.

    1957-01-01

    Static tensile test results are presented for specimens of 2014-T6, 2024-T4, 6061-T6, and 7075-T6 aluminum alloy containing fatigue cracks. The results are found to be in good agreement with the results reported for similar tests from other sources. The results indicate that the presence of a fatigue crack reduced the static strength, in all cases, by an amount larger than the corresponding reduction in net area; the 6061-T6 alloy specimens were least susceptible to the crack and the 7075-T6 alloy specimens were most susceptible. It is indicated that a 7075-T6 specimen may develop as little as one-third of the expected static tensile strength when the fatigue crack was consumed only one-fourth of the original area. It was found that the static strength was substantially higher for specimens which had stop holes drilled at the end of the fatigue crack.

  10. Three Inexpensive Static-Electricity Demonstrations.

    Science.gov (United States)

    Gore, Gordon R.; Gregg, William R.

    1992-01-01

    Describes demonstrations to (1) construct an inexpensive static electricity detector; (2) obtain an abundant supply of either negative or positive charge using household items; and (3) create static electricity using a Tesla coil or Van de Graaff generator. (MDH)

  11. Static Scheduling Strategies for Heterogeneous Systems

    OpenAIRE

    Olivier Beaumont; Arnaud Legrand; Yves Robert

    2012-01-01

    In this paper, we consider static scheduling techniques for heterogeneous systems, such as clusters and grids. We successively deal with minimum makespan scheduling, divisible load scheduling and steady-state scheduling. Finally, we discuss the limitations of static scheduling approaches.

  12. Compatibility of ITER candidate structural materials with static gallium

    International Nuclear Information System (INIS)

    Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 degrees C, corrosion rates are ∼4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400 degrees C are ≥88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400 degrees C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized

  13. 30 CFR 18.26 - Static electricity.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Static electricity. 18.26 Section 18.26 Mineral... § 18.26 Static electricity. Nonmetallic rotating parts, such as belts and fans, shall be provided with a means to prevent an accumulation of static electricity....

  14. A Pedagogical Model of Static Friction

    CERN Document Server

    Pickett, Galen T

    2015-01-01

    While dry Coulombic friction is an elementary topic in any standard introductory course in mechanics, the critical distinction between the kinetic and static friction forces is something that is both hard to teach and to learn. In this paper, I describe a geometric model of static friction that may help introductory students to both understand and apply the Coulomb static friction approximation.

  15. Optoperforation of Intact Plant Cells, Spectral Characterization of Alloy Disorder in InAsP Alloys, and Bimetallic Concentric Surfaces for Metal-Enhanced Fluorescence in Upconverting Nanocrystals

    Science.gov (United States)

    Merritt, Travis R.

    architectures were proposed that retrofit metallic nanoshells to these lanthanide-doped nanocrystals. The typical monometallic construction was rejected in favor of architectures featuring Au-Ag bimetallic concentric surfaces, a decision supported by the considerable overlap of the calculated plasmon modes of the metallic structures with the emission and absorption spectrum of the nanocrystals. Furthermore, precursors of these nanocomposites were synthesized and photoluminescence measurements were carried out, ultimately verifying that these precursors produce the requisite upconversion emissions.

  16. Static Programming of Data Handling

    International Nuclear Information System (INIS)

    The choice of the algorism of data handling is of primary importance in increasing the effectiveness of using digital computers. Both analytical and statistical accuracy of results as well as time and memory requirements are characteristics of an algorism. It is possible in many important cases to obtain an algorism giving both minimum operation time and minimum variance of the output value with a given analytical accuracy. The idea of static programming is to split the digital process into two parts. The first part consists in computing the digital operator in the form of a vector. The second part consists in using this vector to obtain the result as the scalar product of the vector-operator and of an input vector. The time necessary for the second part may be a small fraction of the first and for process reiteration only the second part need be repeated with new input vectors. The theoretical basis of this method is the solution of the generalized discrete Zadeh-Ragazzini’s problem. On application to computer control of nuclear reactors and power plants, static programming permits a number of digital operators to be kept ready for use in the memory of an on-line computer and the on-line computation to be limited to the scalar products. Time and space smoothing, interpolation or prediction of functions, their derivatives and integrals (the functions being given by series of their numerical values) can be performed in such a way. As another example of static programming, harmonic analysis of frequency response is shown. . Digital operators providing given analytical features and the best statistical accuracy of results and requiring minimum of operation time can be useful also as elements of such complicated calculations even where their direct use is not possible. (author)

  17. Registration of Crystallization Process of Ultra-Lightweight Mg-Li Alloys with Use of ATND Method

    OpenAIRE

    A. Białobrzeski; J. Pezda; T. Ciućka

    2007-01-01

    Magnesium alloys are characterized by advantageous ratio of strength and/or elastic modulus to density, that is, can sustain static and dynamic loads similar to iron and aluminium, and additionally feature good vibration damping. Castings from magnesium alloys are lighter with about 20 – 30% than aluminium alloys and with 50 – 75% than iron alloys, that is why they are used in aviation and rocket industry and everywhere the weight of a product is of important significance for conditions of it...

  18. Installment options and static hedging

    OpenAIRE

    Davis, Mark; Schachermayer, Walter; Tompkins, Robert G.

    2001-01-01

    An installment option is a European option in which the premium, instead of being paid up-front, is paid in a series of installments. If all installments are paid the holder receives the exercise value, but the holder has the right to terminate payments on any payment date, in which case the option lapses with no further payments on either side. We discuss pricing and risk management for these options, in particular the use of static hedges to obtain both no-arbitrage pricing bounds and very ...

  19. STATIC ANALYSIS OF LEAF SPRING

    OpenAIRE

    E VENUGOPAL GOUD; G HARINATH GOWD

    2012-01-01

    Leaf springs are special kind of springs used in automobile suspension systems. The advantage of leaf spring over helical spring is that the ends of the spring may be guided along a definite path as it deflects to act as a structural member in addition to energy absorbing device. The main function of leaf spring is not only tosupport vertical load but also to isolate road induced vibrations. It is subjected to millions of load cycles leading to fatigue failure. Static analysis determines the ...

  20. Static Validation of Security Protocols

    DEFF Research Database (Denmark)

    Bodei, Chiara; Buchholtz, Mikael; Degano, P.; Nielson, Hanne Riis; Nielson, Flemming

    2005-01-01

    We methodically expand protocol narrations into terms of a process algebra in order to specify some of the checks that need to be made in a protocol. We then apply static analysis technology to develop an automatic validation procedure for protocols. Finally, we demonstrate that these techniques ...... suffice to identify several authentication flaws in symmetric and asymmetric key protocols such as Needham-Schroeder symmetric key, Otway-Rees, Yahalom, Andrew secure RPC, Needham-Schroeder asymmetric key, and Beller-Chang-Yacobi MSR...

  1. Quasi-static-dynamic formability of AA5052-O sheet under uniaxial and plane-strain tension

    Institute of Scientific and Technical Information of China (English)

    LIU Da-hai; YU Hai-ping; LI Chun-feng

    2009-01-01

    An experimental study on the quasi-static-dynamic formability specified in electromagnetically assisted sheet metal stamping (EMAS) was presented. A series of uniaxial and plane-strain tensile experiments were carried out on AA5052-O sheet by using a combined quasi-static stretching and pulsed electromagnetic forming (EMF) method. Failure strains representing formability beyond conventional quasi-static forming limits are observed under both uniaxial tensile and plane-strain states. The total forming limits of the as-received aluminum alloy undergoing both low and high quasi-static pre-straining are almost similar in quasi-static-dynamic deformation. Ultimate total formability seems to depend largely on the high-velocity loading conditions. Thus, it appears that for quasi-static-dynamic deformation, the quasi-static pre-straining of material is not of primary importance to the additionally useful formability. These observations will enable to develop forming operations that take advantage of this improvement in formability, and will also enable the use of a quasi-static preform fairly close to the quasi-static forming limits without weakening its total formability for design of an EMAS process in shaping large aluminum shell parts like auto body panels.

  2. Static behaviour of induced seismicity

    Science.gov (United States)

    Mignan, Arnaud

    2016-04-01

    The standard paradigm to describe seismicity induced by fluid injection is to apply non-linear diffusion dynamics in a poroelastic medium. I show that the spatio-temporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground, it is not pertinent to the geometrical description of the spatio-temporal patterns of induced seismicity. The proposed model is equivalent to the static stress model for tectonic foreshocks generated by the Non-Critical Precursory Accelerating Seismicity Theory. This study hence verifies the explanatory power of this theory outside of its original scope and provides an alternative physical approach to poroelasticity for the modelling of induced seismicity. The applicability of the proposed geometrical approach is illustrated for the case of the 2006, Basel enhanced geothermal system stimulation experiment. Applicability to more problematic cases where the stress field may be spatially heterogeneous is also discussed.

  3. The equation of state cyclic creep of copper alloys

    OpenAIRE

    Бреславский, Д. В.; Татаринова, О. А.; Хорошилов, О. Н.

    2007-01-01

    The paper describes the technique for derivation of static and cyclic creep-damage constitutive equationsfor bronze alloys under the high temperatures (0,9 – 0,95 of melting temperatures). The use of thedeveloped technique is demonstrated on the examples for two alloys, for which the experimentally andnumerically determined values are compared. The derived state equations were used for simplifiedanalysis of the strain and damage levels in bronze billets in the technological process of continu...

  4. Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

    Directory of Open Access Journals (Sweden)

    Takuo Okuchi

    2015-12-01

    Full Text Available For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg’s law, can be completely removed by alloying two metallic elements that have coherent scattering lengths with opposite signs. An alloy of Ti and Zr, which is known as a TiZr null-matrix alloy, is an ideal combination for such purposes. In this study, we increased the hardness of a TiZr null-matrix alloy via extensive mechanical deformation at high temperatures. We successfully used the resulting product in a high-pressure cell designed for high-static-pressure neutron scattering. This hardened TiZr null-matrix alloy may play a complementary role to normal TiZr alloy in future neutron scattering research under extreme conditions.

  5. Mechanical properties of multicomponent cast high-strength martensitic titanium alloys

    International Nuclear Information System (INIS)

    The investigation of mechanical properties and workability of titanium alloys of the Ta-Al-Mo-V-Sn-Zn-Cu-Fe system with the purpose of alloy development for mold castings with σsub(u) >= 1100 MPa and high resistance to repeated static loads is performed. As optimum alloy for manufacturing power packs and details the alloy of the following composition is chosen: 5.5%Al, 3% Mo; 1.5% V; 1.0% Cu; 0.8% Fe; 1.5% Sn; 3.5% Zr (VT26L) having high stringth σsub(U)=1100... 1250 MPa, satisfactory plasticity ( delta=4...8%, PHI=8... 12%) resistance to repeated-static loads at the VT22 alloy level and satisfactory casting properties. It is established that the VT26L alloy has high level of properties upon casting, without any heat treatment

  6. Palladium-chromium static strain gage for high temperature propulsion systems

    Science.gov (United States)

    Lei, Jih-Fen

    1991-01-01

    The present electrical strain gage for high temperature static strain measurements is in its fine-wire and thin-film forms designed to be temperature-compensated on any substrate material. The gage element is of Pd-Cr alloy, while the compensator is of Pt. Because the thermally-induced apparent strain of this compensated wire strain gage is sufficiently small, with good reproducibility between thermal cycles to 800 C, output figures can be corrected within a reasonable margin of error.

  7. Static Response of Neutron Matter

    Science.gov (United States)

    Buraczynski, Mateusz; Gezerlis, Alexandros

    2016-04-01

    We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star crusts and neutron-rich nuclei. We carry out fully nonperturbative microscopic quantum Monte Carlo calculations of the energy of neutron matter at different densities, as well as different strengths and periodicities of the external potential. In order to remove systematic errors, we examine finite-size effects and the impact of the wave function ansatz. We also make contact with energy-density functional theories of nuclei and disentangle isovector gradient contributions from bulk properties. Finally, we calculate the static density-density linear response function of neutron matter and compare it with the response of other physical systems.

  8. Static properties of Condon domains

    International Nuclear Information System (INIS)

    A new nonlinear differential equation is used for description of the static properties of domain walls of magnetic domains of the non-spin type (Condon domains). This equation is derived on the basis of the exact expression for the thermodynamic potential density, enabling taking into account the oscillating behavior of the magnetization. Inhomogeneity is included in the generalized equation of state. The derived equation is solved analytically. A new shape of the domain wall is presented by the new kink solution of the obtained equation. The width and surface tension of the domain wall is presented as a function of the magnetic field strength, temperature, and Dingle temperature. They exhibit the critical behavior typical of the mean-field theory of second-order phase transitions. The calculated critical exponents are in agreement with nuclear magnetic resonance, muon spin-rotation spectroscopy and Hall probes measurements.

  9. Static and dynamic thyroid scintigraphy

    International Nuclear Information System (INIS)

    Static images as isolated investigation in thyroid diagnosis mainly provides morphologic information, and therefore sonography is largely applied for this purpose. 99mTc-pertechnetate scans or 123I-scans are indicated in cases of malpositions and serve to clarify lesions of unknown dignity. Additionally 201Tl-chloride is suited for examinations with regard to metabolically active thyroid tissue, whereby differential diagnostic laboratory tests must be carried out to exclude parathyroid adenoma. Dynamic thyroid scans before and after regulation tests (suppression, stimulation) reflect the physiological correlation between the iodine avidity of the thyroid, the peripheral thyroid hormone concentrations and the hypophyseal regulation in the TRH-test. The main application of this procedure is the clarification of thyroid autonomy, i.e. indication, detection, quantification or exclusion of thyroid autonomy. For the treatment of immunogenic thyrotoxicosis, dynamic thyroid scintigraphy provides important information about the onset of remission, thus permitting to end thyreostatic therapy. (orig.)

  10. Static Response of Neutron Matter

    CERN Document Server

    Buraczynski, Mateusz

    2015-01-01

    We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star crusts and neutron-rich nuclei. We carry out fully non-perturbative microscopic Quantum Monte Carlo calculations of the energy of neutron matter at different densities, as well as different strengths and periodicities of the external potential. In order to remove systematic errors, we examine finite-size effects and the impact of the wave function ansatz. We also make contact with energy-density functional theories of nuclei and disentangle isovector gradient contributions from bulk properties. Finally, we calculate the static density-density linear response function of neutron matter and compare it with the response of other physical systems.

  11. Static Response of Neutron Matter.

    Science.gov (United States)

    Buraczynski, Mateusz; Gezerlis, Alexandros

    2016-04-15

    We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star crusts and neutron-rich nuclei. We carry out fully nonperturbative microscopic quantum Monte Carlo calculations of the energy of neutron matter at different densities, as well as different strengths and periodicities of the external potential. In order to remove systematic errors, we examine finite-size effects and the impact of the wave function ansatz. We also make contact with energy-density functional theories of nuclei and disentangle isovector gradient contributions from bulk properties. Finally, we calculate the static density-density linear response function of neutron matter and compare it with the response of other physical systems. PMID:27127963

  12. Statics learning from engineering examples

    CERN Document Server

    Emri, Igor

    2016-01-01

    This textbook introduces and explains the basic concepts on which statics is based utilizing real engineering examples. The authors emphasize the learning process by showing a real problem, analyzing it, simplifying it, and developing a way to solve it. This feature teaches students intuitive thinking in solving real engineering problems using the fundamentals of Newton’s laws. This book also: · Stresses representation of physical reality in ways that allow students to solve problems and obtain meaningful results · Emphasizes identification of important features of the structure that should be included in a model and which features may be omitted · Facilitates students' understanding and mastery of the "flow of thinking" practiced by professional engineers.

  13. Static Analysis of Dynamic Languages

    DEFF Research Database (Denmark)

    Madsen, Magnus

    Dynamic programming languages are highly popular and widely used. Java- Script is often called the lingua franca of the web and it is the de facto standard for client-side web programming. On the server-side the PHP, Python and Ruby languages are prevalent. What these languages have in common...... is an expressive power which is not easily captured by any static type system. These, and similar dynamic languages, are often praised for their ease-of-use and flexibility. Unfortunately, this dynamism comes at a great cost: The lack of a type system implies that most errors are not discovered until run......-time. Thus, in the worst-case, these bugs are not uncovered before they are encountered by real users of the system. A further cost is limited tool support: For instance, integrated development environments with code completion, code navigation and automatic refactorings are widely available for languages...

  14. Effect of alloying elements on the hydrogen embrittlement of medium-alloy deposited metal

    International Nuclear Information System (INIS)

    The effect was investigated of the main alloying elements in the metal of electrodes for welding steels upon the tendency to hydrogen embrittlement of medium-alloy built-up metal which was evaluated by the work of inception of cracks and by the work of crack propagation. Specimens from blanks were tested for static bending and rupture. It was established that when developing welding electrodes in was expedient to choose the alloying range of the built-up metal with due regard for the effect of alloying elements upon the hydrogen embrittlement. For a low content of diffusion hydrogen in the built-up metal, the work of inception of a crack diminishes with the increase in carbon, silicon, nickel and molybdenum contents. The work of crack propagation increases with the content of nickel ans varies according to a curve with a maxium as the contents of carbon, silicon, manganese and chromium rise

  15. Modelling of the Mechanical Behaviour of Ultra-Fine Grained Titanium Alloys at High Strain Rates

    OpenAIRE

    Halle, T.; Herzig, N.; Krüger, L; Meyer, L.W.; Musch, D.; Razorenov, S. V.; Skripnyak, E. G.; Skripnyak, V. A.

    2008-01-01

    Results of numerical simulations of the mechanical behaviour of coarse grained and UFG titanium alloys under quasi-static uniaxial compression and plane shock wave loading are presented in this paper. Constitutive equations predict the strain hardening behaviour, the strain rate sensitivity of the flow stress and the temperature softening of titanium alloys with a range of grain sizes from 20 µm to 100 nm. Characteristics of the mechanical behaviour of UFG a and a+ß titanium alloys in wide ra...

  16. Integrity static analysis of COTS/SOUP

    OpenAIRE

    Bishop, P. G.; Bloomfield, R. E.; Clement, T.; Guerra, S.; Jones, C.

    2003-01-01

    This paper describes the integrity static analysis approach developed to support the justification of commercial off-the-shelf software (COTS) used in a safety-related system. The static analysis was part of an overall software qualification programme, which also included the work reported in our paper presented at Safecomp 2002. Integrity static analysis focuses on unsafe language constructs and “covert” flows, where one thread can affect the data or control flow of another thread. The analy...

  17. Effect of microstructure on static and dynamic mechanical properties of high strength steels

    Science.gov (United States)

    Qu, Jinbo

    The high speed deformation behavior of a commercially available dual phase (DP) steel was studied by means of split Hopkinson bar apparatus in shear punch (25m/s) and tension (1000s-1) modes with an emphasis on the influence of microstructure. The cold rolled sheet material was subjected to a variety of heat treatment conditions to produce several different microstructures, namely ferrite plus pearlite, ferrite plus bainite and/or acicular ferrite, ferrite plus bainite and martensite, and ferrite plus different fractions of martensite. Static properties (0.01mm/s for shear punch and 0.001s -1 for tension) of all the microstructures were also measured by an MTS hydraulic machine and compared to the dynamic properties. The effects of low temperature tempering and bake hardening were investigated for some ferrite plus martensite microstructures. In addition, two other materials, composition designed as high strength low alloy (HSLA) steel and transformation induced plasticity (TRIP) steel, were heat treated and tested to study the effect of alloy chemistry on the microstructure and property relationship. A strong effect of microstructure on both static and dynamic properties and on the relationship between static and dynamic properties was observed. According to the variation of dynamic factor with static strength, three groups of microstructures with three distinct behaviors were identified, i.e. classic dual phase (ferrite plus less than 50% martensite), martensite-matrix dual phase (ferrite plus more than 50% martensite), and non-dual phase (ferrite plus non-martensite). Under the same static strength level, the dual phase microstructure was found to absorb more dynamic energy than other microstructures. It was also observed that the general dependence of microstructure on static and dynamic property relationship was not strongly influenced by chemical composition, except the ferrite plus martensite microstructures generated by the TRIP chemistry, which exhibited

  18. Initial cytotoxicity of novel titanium alloys.

    Science.gov (United States)

    Koike, M; Lockwood, P E; Wataha, J C; Okabe, T

    2007-11-01

    We assessed the biological response to several novel titanium alloys that have promising physical properties for biomedical applications. Four commercial titanium alloys [Super-TIX(R) 800, Super-TIX(R) 51AF, TIMETAL(R) 21SRx, and Ti-6Al-4V (ASTM grade 5)] and three experimental titanium alloys [Ti-13Cr-3Cu, Ti-1.5Si and Ti-1.5Si-5Cu] were tested. Specimens (n = 6; 5.0 x 5.0 x 3.0 mm(3)) were cast in a centrifugal casting machine using a MgO-based investment and polished to 600 grit, removing 250 mum from each surface. Commercially pure titanium (CP Ti: ASTM grade 2) and Teflon (polytetrafluoroethylene) were used as positive controls. The specimens were cleaned and disinfected, and then each cleaned specimen was placed in direct contact with Balb/c 3T3 fibroblasts for 72 h. The cytotoxicity [succinic dehydrogenase (SDH) activity] of the extracts was assessed using the MTT method. Cytotoxicity of the metals tested was not statistically different compared to the CP Ti and Teflon controls (p > 0.05). These novel titanium alloys pose cytotoxic risks no greater than many other commonly used alloys, including commercially pure titanium. The promising short-term biocompatibility of these Ti alloys is probably due to their excellent corrosion resistance under static conditions, even in biological environments. PMID:17385227

  19. Corrosion properties of high silicon iron-based alloys in nitric acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of copper and rare-earth elements on corrosion behavior of ~iigh silicon iron-based alloys in nitric acid was studied by means of static and loading current corrosion experiments. The anodic polarization curve was also made to discuss the corrosion mechanism. The examination on alloy microstructure and SEM corrosion pattern showed that when silicon content reached 14.5%, the Fe3Si phase appeared and the primary structure of the iron-base alloy was ferrite. When adding 4.57% copper in the iron alloy, its corrosion resistance in static diluted sulfuric acid was improved while its corrosion resistance and electrochemical corrosion properties in the nitric acid were decreased. In contrast, the addition of rare earth elements could improve the corrosion properties in all above conditions including in static diluted sulfuric acid and in nitric acid.

  20. Structure of molten Al-Si alloys

    International Nuclear Information System (INIS)

    The temperature variation of the structure and microstructure of molten eutectic Al1-xSix alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q)

  1. Structure of molten Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dahlborg, U. [CNRS, Ecole des Mines, Nancy, France; Besser, M. [Ames Laboratory; Calvo-Dahlborg, M. [CNRS, Ecole des Mines, Nancy, France; Cuello, G. [Institut Laue-Langevin (ILL); Dewhurst, C. D. [Institut Laue-Langevin (ILL); Kramer, Matthew J. [Ames Laboratory; Morris, James R [ORNL; Sordelet, Daniel [Ames Laboratory

    2007-01-01

    The temperature variation of the structure and microstructure of molten eutectic Al{sub 1-x}Si{sub x} alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q).

  2. STATIC ANALYSIS OF LEAF SPRING

    Directory of Open Access Journals (Sweden)

    E VENUGOPAL GOUD

    2012-08-01

    Full Text Available Leaf springs are special kind of springs used in automobile suspension systems. The advantage of leaf spring over helical spring is that the ends of the spring may be guided along a definite path as it deflects to act as a structural member in addition to energy absorbing device. The main function of leaf spring is not only tosupport vertical load but also to isolate road induced vibrations. It is subjected to millions of load cycles leading to fatigue failure. Static analysis determines the safe stress and corresponding pay load of the leaf spring and also to study the behavior of structures under practical conditions. The present work attempts to analyze the safeload of the leaf spring, which will indicate the speed at which a comfortable speed and safe drive is possible. A typical leaf spring configuration of TATA-407 light commercial vehicle is chosen for study. Finite element analysis has been carried out to determine the safe stresses and pay loads.

  3. Compatibility of ITER candidate materials with static gallium

    International Nuclear Information System (INIS)

    Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 C, corrosion rates for Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy are ∼ 4.0, 0.5, and 0.03 mm/yr, respectively. Iron, nickel, and chromium react rapidly with gallium. Iron shows greater corrosion than nickel at 400 C (≥ 88 and 18 mm/yr, respectively). The present study indicates that at temperatures up to 400 C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The growth of intermetallic compounds may control the overall rate of corrosion

  4. Local environmental effects in magnetic alloys and multilayers

    International Nuclear Information System (INIS)

    The authors have developed an ab-initio method for calculating the static response functions in substitutional alloys. For magnetic alloys, in addition to the nuclear diffuse scattering, a contribution to the alloy diffuse scattering intensities results from the response of the local moments to changes in the local chemical environment (i.e. jμi/jcj) The authors present results of first-principles calculations of these local response functions in magnetic alloys. These response functions, which may be directly compared to neutron-scattering and Moeβbauer experiments, are derived via a mean-field statistical mechanical description of compositional fluctuations in alloys. The statistical averages are performed via the Korringa-Kohn- Rostoker coherent potential approximation, which incorporates the electronic structure of the high-temperature, chemically disordered state

  5. Static Complexity Analysis of Higher Order Programs

    DEFF Research Database (Denmark)

    Avery, James Emil; Kristiansen, Lars; Moyen, Jean-Yves

    The overall goal of the research presented in this paper is to find^M automatic methods for static complexity analysis of higher order^M programs.......The overall goal of the research presented in this paper is to find^M automatic methods for static complexity analysis of higher order^M programs....

  6. The Neglect of Monotone Comparative Statics Methods

    Science.gov (United States)

    Tremblay, Carol Horton; Tremblay, Victor J.

    2010-01-01

    Monotone methods enable comparative static analysis without the restrictive assumptions of the implicit-function theorem. Ease of use and flexibility in solving comparative static and game-theory problems have made monotone methods popular in the economics literature and in graduate courses, but they are still absent from undergraduate…

  7. Static Material Strength Determined Using a DAC

    Energy Technology Data Exchange (ETDEWEB)

    Cynn, H; Evans, W; Klepeis, J P; Lipp, M; Liermann, P; Yang, W

    2009-06-04

    By measuring sample thickness and pressure gradient using x-ray absorption and x-ray diffraction, respectively, the accurate static yield strengths of Ta and Fe were determined at high pressure. This improved method has several advantages over other similar methods to quantitatively determine static material strength.

  8. Vanadium alloys: development strategy

    International Nuclear Information System (INIS)

    A strategy for the development of vanadium alloys for use in radiation environments is outlined. An attractive reference alloy (V-15Cr-5Ti) has been identified. The critical issues in developing vanadium base alloys are summarized

  9. On the stability of static ghost cosmologies

    International Nuclear Information System (INIS)

    We consider the classical linear stability of a static universe filled with a non-interacting mixture of isotropic radiation and a ghost scalar field. Unlike the conventional Einstein static model, this cosmology is stable against homogeneous and isotropic perturbations. This is shown by means of exact oscillatory solutions about the original static state. We also examine the linear response of the static ghost universe to all types of inhomogeneous fluctuations, namely density, vorticity and gravitational-wave perturbations. The results show that the static background constrains the linear evolution of these distortions, to the extent that density perturbations remain time invariant, vortical distortions vanish and gravitational waves oscillate with constant amplitude. We discuss the potential implications of these results for past-eternal initial states in classical general relativistic cosmology.

  10. On the Stability of Static Ghost Cosmologies

    CERN Document Server

    Barrow, John D

    2009-01-01

    We consider the linear stability of a static universe filled with a non-interacting mixture of isotropic radiation and a ghost scalar field. Unlike the conventional Einstein static model, this cosmology is stable against homogeneous and isotropic perturbations. This is shown by means of exact oscillatory solutions about the original static state. Using covariant techniques, we also examine the linear response of the static ghost universe to all types of inhomogeneous fluctuations, namely density, vorticity and gravitational-wave perturbations. The results show that the static background constrains the linear evolution of these distortions, to the extent that density perturbations remain time invariant, vortical distortions vanish and gravitational waves oscillate with constant amplitude. We discuss potential implications of these results for past-eternal initial states in classical general relativistic cosmology.

  11. On lattice actions for static quarks

    International Nuclear Information System (INIS)

    We introduce new discretizations of the action for static quarks. They achieve an exponential improvement (compared to the Eichten-Hill regularization) on the signal to noise ratio in static-light correlation functions. This is explicitly checked in a quenched simulation and it is understood quantitatively in terms of the self energy of a static quark and the lattice heavy quark potential at zero distance. We perform a set of scaling tests in the Schroedinger functional and find scaling violations in the O(a) improved theory to be rather small - for one observable significantly smaller than with the Eichten-Hill regularization. In addition we compute the improvement coefficients of the static light axial current up to O(g04) corrections and the corresponding renormalization constants non-perturbatively. The regularization dependent part of the renormalization of the b-quark mass in static approximation is also determined. (orig.)

  12. Vein carbonates in the low sulfidation epithermal Au-Ag District of El Peñón, II Región, Chile: environment of formation and exploration implications Carbonatos en vetas en el distrito epitermal de baja sulfuración de El Peñón, II Región, Chile: ambiente de formación e implicancias para la exploración

    Directory of Open Access Journals (Sweden)

    Thomas Bissig

    2007-07-01

    Full Text Available Carbonate minerals are common gangue minerals in the low sulfidation epithermal Au-Ag District of El Peñón, II Región, Chile. They can be subdivided into two principal groups on the basis of the paragenetic relationships. Paragenetically early carbonates occur together with quartz and sulfide minerals in banded veins and are closely associated with precious metal mineralization. These carbonates are compositionally complex, consisting of calcite, finely intermixed with ankerite, kutnohorite, rhodochrosite and dolomite, but also contain up to 0.8 wt% PbC0(3 and up to 4.1 wt% ZnC0(3. In contrast, the paragenetically late carbonates are relatively pure calcite, although dolomite has been recognized locally. Late calcites contain less than 3.5 wt% MnC0(3, less than 0.5 wt% ZnC0(3 and less than 2.7 wt% FeC0(3 and are also distinct from the early carbonates in that they exhibit moderate to intense red fluorescence under short-wave ultraviolet light. The red fluorescence color is likely related to moderate Mn contents in calcite, combined with trace amounts of Pb, but low Fe and Mg concentrations. Late carbonates are interpreted to have precipitated from C0(2-rich steam-heated fluids and are not directly associated with ore. 8(180 compositions of both, early and late carbonates generally range between 21.1 and 14.1 %o relative to the Standard Mean Ocean Water (VSMOW. However, two samples of late calcite yielded 8(180 values of 3 and 5%o, respectively. The calculated composition of water in equilibrium with calcite at the estimated temperature of deposition of 230°Cyielded 8(180 values between 6 and 13%o, but negative values of -3.1 and -5.1%o for two samples of late calcite. Although the low 8(180 values for two of the late calcitesand oxygen isotopic data of vein quartz from earlier studies suggest precipitation from a meteoric fluid, the heavy isotopic signature of most carbonates indicates that the mineralizing fluid was overall heterogeneous. 8

  13. Static and dynamic criticality with uncertainty

    International Nuclear Information System (INIS)

    Highlights: ► The concepts of static and dynamic criticality are redefined in the context of uncertainty. ► Mean reactivity in the static sense may be negative but the associated mean time constant may be positive. ► The static method of reactivity assessment must be viewed with caution when used in safety assessments. -- Abstract: The concepts of static and dynamic reactivity are discussed and the practical differences between them are noted. Special emphasis is given to the use of these concepts in defining uncertainties in reactivity calculations due to uncertainties in cross sections. Currently, in order to define uncertainty, it is the static reactivity that is used. But we show that this may give a non-conservative result compared with the dynamic method. For example, we show that while a static calculation of reactivity involving uncertainty may give a mean value of reactivity which is less than zero, the corresponding dynamic method can yield a value for the time constant which is greater than zero. As the time constant is the physical parameter of interest then the static method must be used with caution.

  14. Static Water Vapor Feed Electrolyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of a static vapor feed electrolyzer utilizing an advanced bipolar plate that produces sub-saturated H2 and O2 is proposed. This novel bipolar design can...

  15. Analytic three-loop static potential

    CERN Document Server

    Lee, Roman N; Smirnov, Vladimir A; Steinhauser, Matthias

    2016-01-01

    We present analytic results for the three-loop static potential of two heavy quarks. The analytic calculation of the missing ingredients is outlined and results for the singlet and octet potential are provided.

  16. Static potentials from an extended gauge symmetry

    International Nuclear Information System (INIS)

    Static potentials derived from the inclusion of more than one vector field in a single simple group are calculated. A confinement mechanism including colourful unphysical particle is discussed. (Author)

  17. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  18. Sawja: Static Analysis Workshop for Java

    OpenAIRE

    Hubert, Laurent; Barré, Nicolas; Besson, Frédéric; Demange, Delphine; Jensen, Thomas; Monfort, Vincent; Pichardie, David; Turpin, Tiphaine

    2010-01-01

    Static analysis is a powerful technique for automatic verification of programs but raises major engineering challenges when developing a full-fledged analyzer for a realistic language such as Java. This paper describes the Sawja library: a static analysis framework fully compliant with Java 6 which provides OCaml modules for efficiently manipulating Java bytecode programs. We present the main features of the library, including (i) efficient functional data-structures for representing program ...

  19. Effect of Aquatic Immersion on Static Balance

    OpenAIRE

    Louder, Talin J.

    2013-01-01

    Objective To quantitatively assess measures of static balance and limits of stability (LOS) in an aquatic environment compared to on land. Methods Fifteen healthy, young adults (23 + or - 2 years) performed 90 s static balance trials on land and aquatic immersion at two different depths (greater trochanter, xiphoid process). Measures of 95% ellipse area and center of pressure (CoP) mean velocity were computed from the force data. Additionally, participants completed a visual analog scale (VAS...

  20. Scalar Field Quantum Inequalities in Static Spacetimes

    OpenAIRE

    Pfenning, Michael J.; Ford, L. H.

    1997-01-01

    We discuss quantum inequalities for minimally coupled scalar fields in static spacetimes. These are inequalities which place limits on the magnitude and duration of negative energy densities. We derive a general expression for the quantum inequality for a static observer in terms of a Euclidean two-point function. In a short sampling time limit, the quantum inequality can be written as the flat space form plus subdominant correction terms dependent upon the geometric properties of the spaceti...

  1. Effect of composition on the high rate dynamic behaviour of tungsten heavy alloys

    Directory of Open Access Journals (Sweden)

    Latif Kesemen

    2015-01-01

    Full Text Available Tungsten heavy alloys are currently used as kinetic energy penetrators in military applications due to their high density and superior mechanical properties. In the literature, quasi-static properties of different tungsten heavy alloys based on W-Ni-Cu and W-Ni-Fe ternary systems are well documented and presented. However, comparison of the dynamic behaviour of these alloys in terms of the correlation between quasi-static mechanical characterization and dynamical properties is lacking. In the present study, dynamic properties of tungsten heavy alloys having different binder phase compositions (90W-7Ni-3Cu and 90W-8Ni-2Fe at different projectile velocities were investigated. The examined and tested alloys were produced through the conventional powder metallurgy route of mixing, cold compaction and sintering. Mechanical characterization of these alloys was performed. In the ballistic tests, cylindrical tungsten heavy alloys with L/D ratio of 3 were impacted to hardened steel target at different projectile velocities. After the ballistic tests, deformation characteristics of test specimens during dynamic loading were evaluated by comparing the change of length and diameter of the specimens versus kinetic energy densities. The study concluded that 90W-8Ni-2Fe alloy has better perforation characteristics than 90W-7Ni-3Cu alloy.

  2. Alloyed steel

    International Nuclear Information System (INIS)

    The composition and properties are listed of alloyed steel for use in the manufacture of steam generators, collectors, spacers, emergency tanks, and other components of nuclear power plants. The steel consists of 0.08 to 0.11% w.w. C, 0.6 to 1.4% w.w. Mn, 0.35 to 0.6% w.w. Mo, 0.02 to 0.07% w.w. Al, 0.17 to 0.37% w.w. Si, 1.7 to 2.7% w.w. Ni, 0.03 to 0.07% w.w. V, 0.005 to 0.012% w.w. N, and the rest is Fe. The said steel showed a sufficiently low transition temperature between brittle and tough structures, a greater depth of hardenability, and better weldability than similar steels. (B.S.)

  3. Electrochemical study of stress corrosion cracking of copper alloys

    International Nuclear Information System (INIS)

    This work deals with the electrochemical study of stress corrosion of copper alloys in aqueous environment. Selective dissolution and electrochemical oxidation are two key-points of the stress corrosion of these alloys. The first part of this thesis treats of these aspects applied to Cu-Au alloys. Measurements have been performed using classical electrochemical techniques (in potentio-dynamic, potentio-static and galvano-static modes). The conditions of occurrence of an electrochemical noise is analysed using signal processing techniques. The impact on the behavior of Cu3Au are discussed. In the second part, the stress corrosion problem is addressed in the case of surface oxide film formation, in particular for Cu-Zn alloys. We have found useful to extend this study to mechanical stress oxidation mechanisms in the presence of an oscillating potential electrochemical system. The aim is to examine the influence of these new electrochemical conditions (galvano-static mode) on the behavior of stressed brass. Finally, the potential distribution at crack tip is calculated in order to compare the different observations

  4. Improve Static Performance Identification Of Inductive Proximity Sensor For a Mobile Robot

    Directory of Open Access Journals (Sweden)

    Hoai Nguyen

    2016-01-01

    Full Text Available Nowadays, inductive proximity sensor and mobile robot are one of the most interesting topics attracting scientists. With enhancement techniques from using sensor for controlling mobile robots which can be developed more in the future. Additionally, measuring of static performance of inductive proximity sensor is also essential because the testing and navigation systems perform more exactly by result information from the experiment by assaying the output signal. In this paper, the hand-made measurement system is used to verify again the static performance of proximity sensor with ferrous, non-ferrous and alloy metal tape. Simultaneously, improve static properties of typical tape metal through the relationship between the output signal and the sensing distance of sensor. According to theoretical basis, the relationship of the static parameters can be determined such as: thickness of metal, sensing distance, dimension of metal, and so on. The testing results have shown the output signal of proximity sensor in the model and theory is not similar. The final data will accommodate some information about the relationship of the thickness of metal tape and the sensing distance of proximity sensor, the different affects of position sensor and optimum operation range of mobile robot.

  5. Static Analysis for JavaScript

    DEFF Research Database (Denmark)

    Jensen, Simon Holm

    dissertation describes the design and implementation of a static analysis for JavaScript that can assist programmers in finding bugs in code during development. We describe the design of a static analysis tool for JavaScript, built using the monotone framework. This analysis infers detailed type information......Web applications present unique challenges to designers of static analysis tools. One of these challenges is the language JavaScript used for client side scripting in the browser. JavaScript is a complex language with many pitfalls and poor tool support compared to other languages. This...... about programs. This information can be used to detect bugs such as null pointer dereferences and unintended type coercions. The analysis is sound, enabling it to prove the absence of certain program errors. JavaScript is usually run within the context of the browser and the DOM API. The major...

  6. Extending and Enhancing SAS (Static Analysis Suite)

    CERN Document Server

    Ho, David

    2016-01-01

    The Static Analysis Suite (SAS) is an open-source software package used to perform static analysis on C and C++ code, helping to ensure safety, readability and maintainability. In this Summer Student project, SAS was enhanced to improve ease of use and user customisation. A straightforward method of integrating static analysis into a project at compilation time was provided using the automated build tool CMake. The process of adding checkers to the suite was streamlined and simplied by developing an automatic code generator. To make SAS more suitable for continuous integration, a reporting mechanism summarising results was added. This suitability has been demonstrated by inclusion of SAS in the Future Circular Collider Software nightly build system. Scalability of the improved package was demonstrated by using the tool to analyse the ROOT code base.

  7. Statics and rotational dynamics of composite beams

    CERN Document Server

    Ghorashi, Mehrdaad

    2016-01-01

    This book presents a comprehensive study of the nonlinear statics and dynamics of composite beams and consists of solutions with and without active elements embedded in the beams. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Two independent numerical solutions for the steady state and the transient responses are presented. The author illustrates that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. Other key areas considered include calculation of the effect of perturbing the steady state solution, coupled nonlinear flap-lag dynamics of a rotating articulated beam with hinge offset and aerodynamic damping, and static and dynamic responses of nonlinear composite beams with embedded anisotropic piezo-composite actuators. The book is intended as a t...

  8. Sawja: Static Analysis Workshop for Java

    Science.gov (United States)

    Hubert, Laurent; Barré, Nicolas; Besson, Frédéric; Demange, Delphine; Jensen, Thomas; Monfort, Vincent; Pichardie, David; Turpin, Tiphaine

    Static analysis is a powerful technique for automatic verification of programs but raises major engineering challenges when developing a full-fledged analyzer for a realistic language such as Java. Efficiency and precision of such a tool rely partly on low level components which only depend on the syntactic structure of the language and therefore should not be redesigned for each implementation of a new static analysis. This paper describes the Sawja library: a static analysis workshop fully compliant with Java 6 which provides OCaml modules for efficiently manipulating Java bytecode programs. We present the main features of the library, including i) efficient functional data-structures for representing a program with implicit sharing and lazy parsing, ii) an intermediate stack-less representation, and iii) fast computation and manipulation of complete programs. We provide experimental evaluations of the different features with respect to time, memory and precision.

  9. Investigating Static and Dynamic Light Scattering

    CERN Document Server

    Sun, Yong

    2011-01-01

    A new size, static radii $R_{s}$, can be measured accurately using Static Light Scattering (SLS) technique when the Rayleigh-Gans-Debye approximation is valid for dilute homogenous spherical particles in dispersion. The method proposed in this work not only can measures the particle size distribution and average molar mass accurately but also enables us to explore Dynamic Light Scattering (DLS) technique further. Detailed investigation of the normalized time auto-correlation function of the scattered light intensity $g^{2)}(\\tau)$ shows that the measurements of DLS can be expected accurately and the static and hydrodynamic radii of nanoparticles are different. Only at some special conditions, the Z-average hydrodynamic radius can be measured accurately at a given scattering angle. The fact that the values of average hydrodynamic radius measured at different scattering angles are consistent or the values of polydispersity index are small does not mean the particle size distribution is narrow or monodisperse.

  10. 30 CFR 57.6602 - Static electricity dissipation during loading.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Static electricity dissipation during loading... MINES Explosives Extraneous Electricity-Surface and Underground § 57.6602 Static electricity dissipation... generates a static electricity hazard— (a) An evaluation of the potential static electricity hazard shall...

  11. MEMS linear and nonlinear statics and dynamics

    CERN Document Server

    Younis, Mohammad I

    2011-01-01

    MEMS Linear and Nonlinear Statics and Dynamics presents the necessary analytical and computational tools for MEMS designers to model and simulate most known MEMS devices, structures, and phenomena. This book also provides an in-depth analysis and treatment of the most common static and dynamic phenomena in MEMS that are encountered by engineers. Coverage also includes nonlinear modeling approaches to modeling various MEMS phenomena of a nonlinear nature, such as those due to electrostatic forces, squeeze-film damping, and large deflection of structures. The book also: Includes examples of nume

  12. Static compensators (STATCOMs) in power systems

    CERN Document Server

    Shahnia, Farhad; Ghosh, Arindam

    2014-01-01

    A static compensator (STATCOM), also known as static synchronous compensator, is a member of the flexible alternating current transmission system (FACTS) devices. It is a power-electronics based regulating device which is composed of a voltage source converter (VSC) and is shunt-connected to alternating current electricity transmission and distribution networks. The voltage source is created from a DC capacitor and the STATCOM can exchange reactive power with the network. It can also supply some active power to the network, if a DC source of power is connected across the capacitor. A STATCOM

  13. Static multiplicities in heterogeneous azeotropic distillation sequences

    DEFF Research Database (Denmark)

    Esbjerg, Klavs; Andersen, Torben Ravn; Jørgensen, Sten Bay; Müller, Dirk; Marquardt, Wolfgang

    In this paper the results of a bifurcation analysis on heterogeneous azeotropic distillation sequences are given. Two sequences suitable for ethanol dehydration are compared: The 'direct' and the 'indirect' sequence. It is shown, that the two sequences, despite their similarities, exhibit very...... different static behavior. The method of Petlyuk and Avet'yan (1971), Bekiaris et al. (1993), which assumes infinite reflux and infinite number of stages, is extended to and applied on heterogeneous azeotropic distillation sequences. The predictions are substantiated through simulations. The static sequence...

  14. Effects of self-irradiation in plutonium alloys

    Science.gov (United States)

    Chung, B. W.; Lema, K. E.; Allen, P. G.

    2016-04-01

    In this paper, we present updated results of self-irradiation effects on 238Pu-enriched 239Pu alloys measured by immersion density, dilatometry, and tensile tests. We obtained the self-irradiation equivalent time of nearly 200 years, nearly 100 years longer than in our previous papers. At this extended aging, we find the rate of decrease in density has slowed significantly, stabilizing around 15.73 g/cc, without signs of void swelling. The volume expansion measured at 35 °C also shows apparent saturation at less than 0.25%. Quasi-static tensile measurement still show gradual increase in the strength of plutonium alloys with age.

  15. Alloy Fabrication Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL’s Alloy Fabrication Facility in Albany, OR, researchers conduct DOE research projects to produce new alloys suited to a variety of applications, from gas...

  16. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Hitesh Sharma; S Prakash

    2007-04-01

    We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts. We have observed a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta- and W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.

  17. Deformation temperature and postdeformation annealing effects on severely deformed TiNi alloy by equal channel angular extrusion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Micron TiNi alloy blocks were fabricated at high temperature by equal channel angular extrusion (ECAE) using hotforged Ti-50.3at%Ni alloy as the raw material and the effects of deformation temperature and postdeformation annealing on the severely deformed TiNi alloy by ECAE were investigated. The results show that the TiNi alloy processed by ECAE undergoes severe plastic deformation, and lowering the deformation temperature and increasing the number of extrusions contribute to grain refinement. When the annealing temperature is below 873 K, static recovery is the main restoration process; when the temperature rises to 973 K, static recrystallization occurs. It is found that fine particles are precipitated when the TiNi alloy processed by ECAE is annealed at 773 K.

  18. High-temperature crack-growth behaviour in Nimonic PE16 and Alloy 718

    International Nuclear Information System (INIS)

    The high-temperature crack-growth behaviour of Nimonic PE16 has been studied at 6500C under cyclic, static, and combined loads, and the results are compared with those of Alloy 718. Crack-growth rates in vacuum under continuous cycling are the same in both alloys, but the rates differ significantly in air. A 1 min hold has no effect on the growth rate of fatigue cracks in Nimonic PE16, but has a large effect in Alloy 718 in air. This difference is due to the difference in their time-dependent crack-growth behaviour. In Alloy 718, time-dependent crack growth occurs readily at low stress intensities. However, in Nimonic PE16, high stress intensities are required to induce crack growth. Furthermore, the crack-growth rates in the two alloys differ by nearly three orders of magnitude. The higher growth rate in Alloy 718 is due largely to environmental effects. Time-dependent crack growth in Nimonic PE16, however, is mostly due to creep, and environment has a negligible effect on the growth. The results indicate that Nimonic PE16 has better resistance to time-dependent crack growth than Alloy 718. Therefore Nimonic PE16 would be expected to perform better than Alloy 718 at high temperatures under cyclic load, particularly at low frequencies, or with hold times as well as under static load. (author)

  19. Static mechanical properties for Ca48Mg27Cu25 bulk metallic glass by ultrasonic velocity measurement

    International Nuclear Information System (INIS)

    The static mechanical properties of a Ca48Mg27Cu25 bulk metallic glass were investigated using a technique of ultrasonic measurement and compressive test. The Young's modulus (E), Poisson's ratio (v), shear modulus (G) and bulk modulus (B) for the Ca48Mg27Cu25 alloy at room temperature are significantly smaller than those for Zr- and Pd- based bulk metallic glasses. The values of E, v, G and B for the Ca48Mg27Cu25 alloy are 29.8GPa, 0.230, 12.1GPa and 18.4GPa, respectively. The results of compression test for the Ca48Mg27Cu25 alloy have been also described.

  20. Thermal mechanic processing effects on the microstructural evolution of Al-Li alloys

    International Nuclear Information System (INIS)

    The investigation of the effects of different thermomechanical treatments on the microstructure of alloys 8090 and 8091 (Al-Li-Cu-MgZr) is the aim of the present work. In this context, the intervention of static recrystallization during solution treatment after hot working is the determining factor on the final microstructure of products in form of plates. The results could reveal that the rolling temperature is a very important variable if microstructural control is to be achieved in these alloys. (author)

  1. The longitudinal static stability of tailless aircraft

    OpenAIRE

    de Castro, Helena V.

    2001-01-01

    This paper describes the development of a simple theory of the longitudinal controls fixed static stability of tailless aeroplanes. The classical theory, as developed for the conventional aircraft, is modified to accommodate the particular features of the tailless aeroplanes. The theory was then applied to a particular blended-wing-body tailless civil transport aircraft, BWB-98.

  2. The atomic and molecular reaction statics

    Institute of Scientific and Technical Information of China (English)

    ZHU; ZhengHe

    2007-01-01

    This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e. the group theoretical derivation of molecular electronic states, the principle of microscopic reversibility, the principle of microscopic transitivity and the optimum energy process rule. AMRS has been developed for about twenty years.

  3. Static Validation of a Voting Protocol

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Rosenkilde; Andersen, Esben Heltoft; Nielson, Hanne Riis

    The desired security properties of electronic voting protocols include verifiability, accuracy, democracy and fairness. In this paper we use a static program analysis tool to validate these properties for one of the classical voting protocols under appropriate assumptions. The protocol is...

  4. Effects of insoles contact on static balance

    Science.gov (United States)

    Shin, Ju Yong; Ryu, Young Uk; Yi, Chae Woo

    2016-01-01

    [Purpose] This study examined the effect of the degree of the contact area between the insoles and soles on static balance. [Subjects and Methods] Thirteen healthy male and female adults voluntarily participated. All of the subjects wore three different types of insoles (no orthotic insole, partial contact, full contact) in the present experiment. The subjects were instructed to place both feet parallel to each other and maintain static balance for 30 seconds. Center of pressure parameters (range, total distance, and mean velocity) were analyzed. [Results] The results show that the anteroposterior range and mediolateral (ML) total distance and velocity decreased when orthotic insoles with partial contact or full contact were used in comparison to when a flat insole (no orthotic insole) was used. Also, the ML range and total distance were lower with full contact than in the other two conditions. These results indicate that static balance improves as the degree of contact between the soles and insoles increases. [Conclusion] The results of this study suggests that using insoles with increased sole contact area would improve static balance ability.

  5. Static Analysis for Java Servlets and JSP

    DEFF Research Database (Denmark)

    Kirkegaard, Christian; Møller, Anders

    2006-01-01

    We present an approach for statically reasoning about the behavior of Web applications that are developed using Java Servlets and JSP. Specifically, we attack the problems of guaranteeing that all output is well-formed and valid XML and ensuring consistency of XHTML form fields and session state...

  6. Static Analysis of XML Transformations in Java

    DEFF Research Database (Denmark)

    Kirkegaard, Christian; Møller, Anders; Schwartzbach, Michael I.

    2004-01-01

    of XML documents to be defined, there are generally no automatic mechanisms for statically checking that a program transforms from one class to another as intended. We introduce Xact, a high-level approach for Java using XML templates as a first-class data type with operations for manipulating XML values...

  7. Energy consumption in static muscle contraction

    NARCIS (Netherlands)

    Koerhuis, CL; Hof, AL; van der Heide, F.M.

    2003-01-01

    Energy consumption during static contraction of the human triceps surae muscles was studied in 11 healthy subjects. The subjects had to stand intermittently on the left and then right foot at different frequencies (for periods of 15 s, 10 s or 5 s), first on the whole foot and then on the forefoot.

  8. PARAMETRIC RESONANSE IN STATICALLY INDETERMINATE FRAMES

    Directory of Open Access Journals (Sweden)

    Yu.V. Vorona

    2014-12-01

    Full Text Available The technique for development and reduction of discrete dynamics models of frames is presented. Construction of the models is carried out using finite element method, generalized coordinates and tools of modern computer software. Parametric resonance in a statically indeterminate frame caused by external excitations is investigated. Main instability domains of the frame are determined.

  9. New schemes of static mass spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Baisanov, O.A. [Military Institute of Air Defense Forces, Aktobe (Kazakhstan); Doskeyev, G.A. [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan); Spivak-Lavrov, I.F., E-mail: baisanov@mail.ru [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan)

    2011-07-21

    Different possibilities to increase the 'quality', or Q-quantity, of static mass spectrometers by expanding the ion beam before it enters the magnetic field are analyzed. The design of mass spectrometers using a cone-shaped achromatic prism is discussed. Different variants of achromatic mass spectrometers using electrostatic prisms and sector magnetic fields are also considered.

  10. Static Multiresolution Grids with Inline Hierarchy Information

    CERN Document Server

    Müller, Gero

    2015-01-01

    For numerical simulations of cosmic-ray propagation fast access to static magnetic field data is required. We present a data structure for multiresolution vector grids, which are optimized for fast access, low overhead and shared memory use. The hierarchy information is encoded into the grid itself, reducing the memory overhead.

  11. Static Properties of A-Hypernuclei

    Institute of Scientific and Technical Information of China (English)

    谭玉红; 罗延安; 宁平治; 马中玉

    2001-01-01

    Static Properties of A-hypernuclei are calculated self-consistntly in the relativistic mean-field model. The effect of A on the core nucleons are investigated. It is found that the rms radii of the neutron become smaller than those of ordinary nuclei, when a closed-shell nuclear core is embedded in a 1s1/2 A hyperon.

  12. Static, Lightweight Includes Resolution for PHP

    NARCIS (Netherlands)

    Hills, M.A.; Klint, P.; Vinju, J.J.

    2014-01-01

    Dynamic languages include a number of features that are challenging to model properly in static analysis tools. In PHP, one of these features is the include expression, where an arbitrary expression provides the path of the file to include at runtime. In this paper we present two complementary analy

  13. Static and evolutionary quantum public goods games

    Science.gov (United States)

    Liao, Zeyang; Qin, Gan; Hu, Lingzhi; Li, Songjian; Xu, Nanyang; Du, Jiangfeng

    2008-05-01

    We apply the continuous-variable quantization scheme to quantize public goods game and find that new pure strategy Nash equilibria emerge in the static case. Furthermore, in the evolutionary public goods game, entanglement can also contribute to the persistence of cooperation under various population structures without altruism, voluntary participation, and punishment.

  14. Static progressive splinting for posttraumatic elbow stiffness

    NARCIS (Netherlands)

    J.N. Doornberg; D. Ring; J.B. Jupiter

    2006-01-01

    Objectives: To determine the value of static progressive splinting in helping patients with posttraumatic elbow stiffness regain functional motion and avoid operative treatment for stiffness. Design: Retrospective case series. Setting: Level I Trauma Center. Patients and Intervention: Over a 3-year

  15. Static consensus in passifiable linear networks

    OpenAIRE

    Junussov, Ibragim A.

    2014-01-01

    Sufficient conditions of consensus (synchronization) in networks described by digraphs and consisting of identical determenistic SIMO systems are derived. Identical and nonidentical control gains (positive arc weights) are considered. Connection between admissible digraphs and nonsmooth hypersurfaces (sufficient gain boundary) is established. Necessary and sufficient conditions for static consensus by output feedback in networks consisting of certain class of double integrators are rediscover...

  16. Experience of static electrification in power transformer

    International Nuclear Information System (INIS)

    This document is a discussion of a static electrification event in each of the 1050 MVA units installed at the Koeburg Nuclear Power Plant in South Africa. Results of a tear-down inspection performed after the event are given, as is an analysis of the event. A number of photographs are included

  17. Static Typing for Object-Oriented Programming

    DEFF Research Database (Denmark)

    Schwartzbach, Michael Ignatieff; Palsberg, Jens

    1994-01-01

    We develop a theory of statically typed object-oriented languages. It represents classes as labeled, regular trees, types as finit sets of classes , and sub-classing as a partial order on trees. We show that our sub-classing order strictly generalizes inheritance, and that a novel genericity mech...

  18. The static and nonstatic electrical solenoids

    International Nuclear Information System (INIS)

    We propose the set of charge and current densities which realize static and nonstatic electrical solenoids. Their properties are discussed. The question on the physical meaning of the electromagnetic potentials outside the solenoids and their experimental verification remains to be opened. 19 refs.; 4 figs

  19. New schemes of static mass spectrometers

    International Nuclear Information System (INIS)

    Different possibilities to increase the 'quality', or Q-quantity, of static mass spectrometers by expanding the ion beam before it enters the magnetic field are analyzed. The design of mass spectrometers using a cone-shaped achromatic prism is discussed. Different variants of achromatic mass spectrometers using electrostatic prisms and sector magnetic fields are also considered.

  20. QuickChecking Static Analysis Properties

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Møller, Anders

    2015-01-01

    A static analysis can check programs for potential errors. A natural question that arises is therefore: who checks the checker? Researchers have given this question varying attention, ranging from basic testing techniques, informal monotonicity arguments, thorough pen-and-paper soundness proofs, ...

  1. Terbium base alloy

    International Nuclear Information System (INIS)

    Composition of terbium-5-7 % gadolinium alloy with high magnetostriction sensitivity (180x10-8 Oe) is suggested. The alloy is designed for usage under cryogenic temperature within 500-1500 Oe fields. Magnetostriction sensitivity of the suggested alloy is by 2-2.5 times higher, than that of well-known before one. 1 tab

  2. The cyclic oxidation resistance at 1200 C of Beta-NiAl, FeAl, and CoAl alloys with selected third element additions

    International Nuclear Information System (INIS)

    The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale

  3. F-Alloy: An Alloy Based Model Transformation Language

    OpenAIRE

    Gammaitoni, Loïc; Kelsen, Pierre

    2015-01-01

    Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In this paper we introduce the concept of functional Alloy modules. In essence a functional Alloy module can be viewed as an Alloy module representing a model transformation. We describe a sublanguage of Alloy called F-Alloy that allows the specification of functional Alloy modules. Module...

  4. Static and Dynamic Analysis of a Pump Impeller with a Balancing Device Part I: Static Analysis

    Directory of Open Access Journals (Sweden)

    Kundera C.

    2014-08-01

    Full Text Available This part of the work presents the design and static analysis of an impeller for a single-stage pump. The impeller is directly connected with a balancing device. The impeller needs to have a properly designed system of longitudinal and lateral clearances on both sides. With the simplifying assumptions concerning the flow and distribution of pressure in the longitudinal and lateral clearances, the static analysis involved deriving relationships between the impeller geometry and the basic performance parameters of the pump. A numerical example was used to show the calculation procedure of static characteristics for the predetermined parameters

  5. Mechanodynamical analysis of nickel-titanium alloys for orthodontics application

    International Nuclear Information System (INIS)

    Nickel-titanium alloys may coexist in more than one crystalline structure. There is a high temperature phase, austenite, and a low temperature phase, martensite. The metallurgical basis for the superelasticity and the shape memory effect relies in the ability of these alloys to transform easily from one phase to another. There are three essential factors for the orthodontist to understand nickel-titanium alloys behaviour: stress; deflection; and temperature. These three factors are related to each other by the stress-deflection, stress-temperature and deflection-temperature diagrams. This work was undertaken with the objective to analyse commercial nickel-titanium alloys for orthodontics application, using the dynamical mechanical analyser - DMA. Four NiTi 0,017 X 0,025'' archwires were studied. The archwires were Copper NiTi 35 deg C (Ormco), Neo Sentalloy F200 (GAC), Nitinol Superelastic (Unitek) and NiTi (GAC). The different mechanodynamical properties such as elasticity and damping moduli were evaluated. Each commercial material was evaluated with and without a 1 N static force, aiming to evaluate phase transition temperature variation with stress. The austenitic to martensitic phase ratio, for the experiments without static force, was in the range of 1.59 to 1.85. For the 1 N static force tests the austenitic to martensitic phase ratio, ranged from 1.28 to 1.57 due to the higher martensite elasticity modulus. With elastic modulus variation with temperature behaviour, the orthodontist has the knowledge of the force variation applied in the tooth in relation to the oral cavity temperature change, for nickel-titanium alloys that undergo phase transformation. The damping capacity of the studied alloys depends on the materials state: martensitic phase; austenitic phase or during phase transformation. The martensitic phase shows higher dumping capacity. During phase transformation, an internal friction peak may be observed for the CuNiTi 35 deg C and Neo Sentalloy F

  6. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  7. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  8. Prediction on the viscosity of multi-component melts with a new geometric model

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A geometric model for calculating the viscosity of multi-component melt from related binary physicochemistry properties was derived based on Chou's thermodynamic geometric model. The model derived was employed to predict the viscosity of Au-Ag-Cu alloys. The results show that the calculated viscosity for Au-Ag-Cu alloys meet the experimental data very well. In addition, the viscosity of Bi-Sn-In systems was also predicted with this model.

  9. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  10. Dynamic Simulation for Hysteresis in Shape Memory Alloy under Tension

    Institute of Scientific and Technical Information of China (English)

    WANG Ping; ZHAO Jian-Bo; TANG Shao-Qiang

    2008-01-01

    We demonstrate that the Suliciu model is capable to model the hysteresis phenomenon observed experimentally in NiTi shape memory alloy micro-tubes.This model allows a class of stationary phase interfaces.By a series of fully dynamic numerical simulations that mimic quasi-static loading and unloading,the nominal stress-strain curve exhibits a big hysteresis loop,which quantitatively agrees with the experimental results.

  11. Static and Dynamic Analysis of a Pump Impeller with a Balancing Device Part I: Static Analysis

    OpenAIRE

    Kundera C.; Martsinkovsky V.A.

    2014-01-01

    This part of the work presents the design and static analysis of an impeller for a single-stage pump. The impeller is directly connected with a balancing device. The impeller needs to have a properly designed system of longitudinal and lateral clearances on both sides. With the simplifying assumptions concerning the flow and distribution of pressure in the longitudinal and lateral clearances, the static analysis involved deriving relationships between the impeller geometry and the basic perfo...

  12. Static and repeated-strength static f stud joints made by percussion capacitor-type welding

    International Nuclear Information System (INIS)

    Results of the experimental study of static and repeated-static strength of stud joints, made by percussion capacitoA-type welding, are presented. Under conditions of stretching, cut and bend the effect of loading type, cycle asymmetry, sublayer material and oxide layer on its surface, as well as defects of welding in the form of undercuttings and caverns on the resistance of the joints to repeated-alternating loading on the basis of 5000 cycles, has been studied

  13. Static Thrust Analysis of the Lifting Airscrew

    Science.gov (United States)

    Knight, Montgomery; Hefner, Ralph A

    1937-01-01

    This report presents the results of a combined theoretical and experimental investigation conducted at the Georgia School of Technology on the static thrust of the lifting air screw of the type used in modern autogiros and helicopters. The theoretical part of this study is based on Glauert's analysis but certain modifications are made that further clarify and simplify the problem. Of these changes the elimination of the solidity as an independent parameter is the most important. The experimental data were obtained from tests on four rotor models of two, four, and five blades and, in general, agree quite well with the theoretical calculations. The theory indicates a method of evaluating scale effects on lifting air screws, and these corrections have been applied to the model results to derive general full-scale static thrust, torque, and figure-of-merit curves for constant-chord, constant-incidence rotors. Convenient charts are included that enable hovering flight performance to be calculated rapidly.

  14. Static spherically symmetric wormholes with isotropic pressure

    Science.gov (United States)

    Cataldo, Mauricio; Liempi, Luis; Rodríguez, Pablo

    2016-06-01

    In this paper we study static spherically symmetric wormhole solutions sustained by matter sources with isotropic pressure. We show that such spherical wormholes do not exist in the framework of zero-tidal-force wormholes. On the other hand, it is shown that for the often used power-law shape function there are no spherically symmetric traversable wormholes sustained by sources with a linear equation of state p = ωρ for the isotropic pressure, independently of the form of the redshift function ϕ (r). We consider a solution obtained by Tolman at 1939 for describing static spheres of isotropic fluids, and show that it also may describe wormhole spacetimes with a power-law redshift function, which leads to a polynomial shape function, generalizing a power-law shape function, and inducing a solid angle deficit.

  15. Static Checking of Interrupt-driven Software

    DEFF Research Database (Denmark)

    Brylow, Dennis; Damgaard, Niels; Palsberg, Jens

    2001-01-01

    Resource-constrained devices are becoming ubiquitous. Examples include cell phones, palm pilots, and digital thermostats. It can be difficult to fit required functionality into such a device without sacrificing the simplicity and clarity of the software. Increasingly complex embedded systems...... require extensive brute-force testing, making development and maintenance costly. This is particularly true for system components that are written in assembly language. Static checking has the potential of alleviating these problems, but until now there has been little tool support for programming at the...... assembly level. In this paper we present the design and implementation of a static checker for interrupt-driven Z86-based software with hard real-time requirements. For six commercial microcontrollers, our checker has produced upper bounds on interrupt latencies and stack sizes, as well as verified...

  16. Variational approach for static mirror structures

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, E. A. [P.N. Lebedev Physical Institute RAS, 53 Leninsky Ave., 119991 Moscow (Russian Federation); Space Research Institute RAS, 84/32 Profsoyuznaya str., 117997 Moscow (Russian Federation); L.D. Landau Institute for Theoretical Physics RAS, 2 Kosygin str., 119334 Moscow (Russian Federation); Passot, T.; Sulem, P. L. [UNS, CNRS, Observatoire de la Côte d' Azur, CS 34229, 06304 Nice Cedex 4 (France); Ruban, V. P. [L.D. Landau Institute for Theoretical Physics RAS, 2 Kosygin str., 119334 Moscow (Russian Federation)

    2015-04-15

    Anisotropic static plasma equilibria where the parallel and perpendicular pressures are only functions of the amplitude of the local magnetic field are shown to be amenable to a variational principle with a free energy density given by the parallel tension. This approach is used to demonstrate that two-dimensional small-amplitude static magnetic holes constructed from a Grad-Shafranov type equation slightly below the (subcritical) mirror instability threshold identify with lump solitons of KPII equation, but turn out to be unstable. Differently, large-amplitude magnetic structures, which are stable as they realize a minimum of the free energy, are computed using a gradient method within two-dimensional numerical simulations where the regularizing effect of finite Larmor radius corrections is retained. Interestingly, these structures transform from stripes to bubbles when the angle of the magnetic field with the coordinate plane is increased.

  17. Einstein static universe in braneworld scenario

    International Nuclear Information System (INIS)

    The stability of Einstein static universe against homogeneous scalar perturbations in the context of braneworld scenario is investigated. The stability regions are obtained in terms of the constant geometric linear equation of state parameter ωextr=pextr/ρextr and are studied for each evolutionary era of the universe. The results are discussed for the case of closed, open or flat universe in each era under the obtained restricting conditions. We also briefly investigate the stability against vector and tensor perturbations. Contrary to the classical general relativity, it is found that a stable Einstein static universe may exist in a braneworld theory of gravity against scalar, vector and tensor perturbations for some suitable values and ranges of the cosmological parameters.

  18. Static inelastic analysis of RC shear walls

    Institute of Scientific and Technical Information of China (English)

    陈勤; 钱稼茹

    2002-01-01

    A macro-model of a reinforced concrete (RC) shear wall is developed for static inelastic analysis. The model iscomposed of RC column elements and RC membrane elements. The column elements are used to model the boundary zone andthe membrane elements are used to model the wall panel. Various types of constitutive relationships of concrete could beadopted for the two kinds of elements. To perform analysis, the wall is divided into layers along its height. Two adjacent layersare connected with a rigid beam. There are only three unknown displacement components for each layer. A method called singledegree of freedom compensation is adopted to solve the peak value of the capacity curve. The post-peak stage analysis isperformed using a forced iteration approach. The macro-model developed in the study and the complete process analysismethodology are verified by the experimental and static inelastic analytical results of four RC shear wall specimens.

  19. Static spherically symmetric wormholes with isotropic pressure

    CERN Document Server

    Cataldo, Mauricio; Rodríguez, Pablo

    2016-01-01

    In this paper we study static spherically symmetric wormhole solutions sustained by matter sources with isotropic pressure. We show that such spherical wormholes do not exist in the framework of zero-tidal-force wormholes. On the other hand, it is shown that for the often used power-law shape function there is no spherically symmetric traversable wormholes sustained by sources with a linear equation of state $p=\\omega \\rho$ for the isotropic pressure, independently of the form of the redshift function $\\phi(r)$. We consider a solution obtained by Tolman at 1939 for describing static spheres of isotropic fluids, and show that it also may describe wormhole spacetimes with a power-law redshift function, which leads to a polynomial shape function, generalizing a power-law shape function, and inducing a solid angle deficit.

  20. LAMINAR MIXING IN SMX STATIC MIXERS

    Directory of Open Access Journals (Sweden)

    MUSHTAK AL-ATABI

    2007-04-01

    Full Text Available This paper experimentally examines the performance of a commercial static mixer (SMX. Experiments were carried out to obtain the pressure drop across different numbers of mixing elements (4, 8, 12 and 16. The quality of mixing was visually assessed using flow visualization techniques. Experiments were performed for Reynolds number between 50 and 3000 (based on the unobstructed pipe diameter. The presence of the mixing elements in the flow stream promotes a non-laminar, turbulent-like flow which considerably enhances the mixing. Addition of more mixing elements triggered mixing in the flow at lower Reynolds numbers but this was achieved at the expense of higher pressure drop. This work represents the first stage of an on going work to develop correlations to assess the mixing quality and pressure loss in the SMX static mixers.

  1. Optimal Static Range Reporting in One Dimension

    DEFF Research Database (Denmark)

    Alstrup, Stephen; Brodal, Gerth Stølting; Rauhe, Theis

    query interval, we present an optimal data structure with linear space cost and with query time linear in the number of integers reported. This result holds in the unit cost RAM model with word size w and a standard instruction set. We also present a linear space data structure for approximate range......We consider static one dimensional range searching problems. These problems are to build static data structures for an integer set S \\subseteq U, where U = \\{0,1,\\dots,2^w-1\\}, which support various queries for integer intervals of U. For the query of reporting all integers in S contained within a...... counting. A range counting query for an interval returns the number of integers in S contained within the interval. For any constant &egr;>0, our range counting data structure returns in constant time an approximate answer which is within a factor of at most 1+&egr; of the correct answer....

  2. Static solitons in more than one dimension

    International Nuclear Information System (INIS)

    The most important development of the last decade in particle physics and field theory has undoubtedly been the advent of hidden-symmetric gauge theories. One of the more interesting by-products of this development has been the discovery that hidden-symmetric gauge theories admit static solutions to the field equations which are regular everywhere and for which the energy is finite. Such solutions will be called solitons. The hidden-symmetric gauge solutions exist for n space dimensions, where 1 <= n <= 4, and the purpose of this lecture is to describe the static soliton solutions for 2 <= n <= 4. To put the solutions in perspective, however, a section is first devoted to a description of the hidden-symmetric gauge theories and their role vis-a-vis the fundamental interaction. (orig./WL)

  3. Kerr metric, static observers and Fermi coordinates

    International Nuclear Information System (INIS)

    The coordinate transformation which maps the Kerr metric written in standard Boyer-Lindquist coordinates to its corresponding form adapted to the natural local coordinates of an observer at rest at a fixed position in the equatorial plane, i.e., Fermi coordinates for the neighbourhood of a static observer world line, is derived and discussed in a way which extends to any uniformly circularly orbiting observer there

  4. Static stress analysis of CANFLEX fuel bundles

    International Nuclear Information System (INIS)

    The static stress analysis of CANFLEX bundles is performed to evaluate the fuel structural integrity during the refuelling service. The structure analysis is carried out by predicting the drag force, stress and displacements of the fuel bundle. By the comparison of strength tests and analysis results, the displacement values are well agreed within 15%. The analysis shows that the CANFLEX fuel bundle keep its structural integrity. 24 figs., 6 tabs., 12 refs. (Author) .new

  5. Static Posturography in Aging and Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Guntram W. Ickenstein

    2012-08-01

    Conclusions: The platform Romberg test with closed eyes detected significant differences in elderly people and patients with Parkinson's disease, which could be objectively quantified with static posturography testing. Age alone showed significant changes, only detectable with closed eyes. Therefore balance testing with a new computerized approach could help to identify balance problems in a geriatric assessment in clinical routine, especially with the parameters marked area and mean sway.

  6. Thermochromic filters effect on static light

    OpenAIRE

    Cabral, Isabel; Souto, A. Pedro

    2012-01-01

    Is it possible to change the environment light without changing or act in the light source? Smart textiles materials and new technologies open the possibility to introduce dynamic behaviours to elements that use to be static. Using the ability of Colour Change Materials to answer to external stimulus, this paper studies how colour variation of textile samples, treated with reversible thermochromic pigments, filter the artificial light intensity that go by (pass) through it. In this work a ...

  7. Static and dynamic weighing of vehicles

    OpenAIRE

    Meluš, Ladislav

    2014-01-01

    The work discusses the basic principles used in systems of static and dynamic weighing vehicles and is formally divided into a theoretical part and a practical part. The theoretical part describes the basic principles of strain weighing, types and functions of truck scales, related standards and evaluate the properties currently available types of scales. In the practical part contains a conceptual design of automated weighing station based WIM (Weighing in motion).

  8. Plate shell structures - statics and stability

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2008-01-01

    This paper describes the basic structural system, statics and spatial stability of plate shells. The structural system can be considered as a single layer of planar elements, where each element only transfers in-plane (membrane) forces to its neighbouring elements. External out-of-plane loads are...... system is dual to that of a spatial truss system, which means the stringer system [1] can be applied to plate-shell structures....

  9. Statics and dynamics of fluids in nanotubes

    OpenAIRE

    Gouin, Henri

    2012-01-01

    The purpose of this article is to study the statics and dynamics of nanotubes by using the methods of continuum mechanics. The nanotube can be filled with only a liquid or a vapour phase according to the physicochemical characteristics of the wall and to the disjoining pressure associated with the liquid and vapour mother bulks of the fluid, regardless of the nature of the external mother bulk. In dynamics, flows through nanotubes can be much more important than classical Poiseuille flows. Wh...

  10. Exploiting statically schedulable regions in dataflow programs

    OpenAIRE

    Gu, Ruirui; Janneck, Jörn W.; Raulet, Mickaël; Bhattacharyya, Shuvra S.

    2009-01-01

    Dataflow descriptions have been used in a wide range of Digital Signal Processing (DSP) applications, such as multi-media processing, and wireless communications. Among various forms of dataflow modeling, Synchronous Dataflow (SDF) is geared towards static scheduling of computational modules, which improves system performance and predictability. However, many DSP applications do not fully conform to the restrictions of SDF modeling. More general dataflow models, such as CAL (Eker and Janneck ...

  11. SACO: Static analyzer for concurrent objects

    OpenAIRE

    Albert Albiol, Elvira; Arenas Sánchez, Purificación; Flores Montoya, A.; Genaim, Samir; Gómez-Zamalloa Gil, Miguel; Martín Martín, Enrique; Puebla, G.; Román Díez, Guillermo

    2014-01-01

    We present the main concepts, usage and implementation of SACO, a static analyzer for concurrent objects. Interestingly, SACO is able to infer both liveness(namely termination and resource boundedness) and safety properties (namely deadlock freedom) of programs based on concurrent objects. The system integrates auxiliary analyses such as points-to and may-happen-in-parallel, which are essential for increasing the accuracy of the aforementioned more complex properties. SACO provides accurate ...

  12. An invariant distribution in static granular media

    OpenAIRE

    T. Aste; Di Matteo, T.; Saadatfar, M.; Senden, T. J.; Schroter, M.; Swinney, Harry L.

    2006-01-01

    We have discovered an invariant distribution for local packing configurations in static granular media. This distribution holds in experiments for packing fractions covering most of the range from random loose packed to random close packed, for beads packed both in air and in water. Assuming only that there exist elementary cells in which the system volume is subdivided, we derive from statistical mechanics a distribution that is in accord with the observations. This universal distribution fu...

  13. A Static Assurance Analysis of Android Applications

    OpenAIRE

    Karim O. Elish; Yao, Danfeng (Daphne); Ryder, Barbara G.; Jiang, Xuxian

    2013-01-01

    We describe an efficient approach to identify malicious Android applications through specialized static program analysis. Our solution – referred to as user intention program dependence analysis – performs offline analysis to find the dependence relations between user triggers and entry points to methods providing critical system functions. Analyzing these types of dependences in programs can identify the privileged operations (e.g., file, network operations and sensitive data access) that ar...

  14. Effect of Electric Field on Conductivity and Vickers Hardness of an A1-Li Alloy

    Institute of Scientific and Technical Information of China (English)

    刘兵; 陈大融; 陈铮; 王永欣; 李晓玲

    2003-01-01

    Static electric fields were applied on an aluminium-lithium alloy during solution treatment.The conductivity and Vickers hardness of the quenched Al-Li alloy is changed with the effect of electric field.The Vickers hardness increases with the applied electric field for a certain solutionizing time but decreases with the time under an electric field.In the absence of the electric field,the Vickers hardness and the conductivity increase synchronously,while reversed after electric field treatment.Positive and negative electric fields had the similar effect.The change of the local electron density in alloy caused by electric field is presented to explain the effect.

  15. Simulation Study of Dynamic Properties in PD-AL Liquid Alloys

    International Nuclear Information System (INIS)

    Liquid properties such as diffusivity, viscosity and dynamic structure factor of Pd and Al metals and their alloys are studied by using Sutton-Chen potential. Calculations are performed for pure metallic and alloy cases. Parinello-Rahman formalism employed for alloy simulation. New potential parameters, evaluated by Cagin et al. (Q-SC parameters), are used for Pd metal. The physical properties such as diffusion coefficients, viscosity and dynamic and static structure factors are calculated and compared to experimental data. Transferability of parameters from solid to liquid states is discussed. Key Words: Palladium, Aluminum, MD simulation, Dynamic structure factor, viscosity

  16. The effect of thermohydrogen treatment on the structure and properties of casts obtained from titanium alloys

    International Nuclear Information System (INIS)

    The method based on the combination of high temperature gas-static and thermal hydrogen treatments is suggested to increase mechanical properties of cast pseudo-α and (α+β)-titanium alloys. The study is carried out using alloys VT20L, VT23L and alloy Ti-6%Al-2%Mo-4%Zr-2%Sn. It is shown that the method proposed provides the change in a cast structure, an increase in density of castings, an increase of strength properties by 10-20% and fatigue by a factor of 1.5-2 at satisfactory ductility and impact strength

  17. Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

    OpenAIRE

    Takuo Okuchi; Akinori Hoshikawa; Toru Ishigaki

    2015-01-01

    For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg’s law, can be completely removed by alloying two metallic elements that have coherent scattering lengths with opposite signs. An alloy of Ti and Zr, which is known as a TiZr null-matrix alloy, is an ideal combination for such purposes. In this ...

  18. Electrochemical degradation of carbamazepine using modified electrode with graphene-AuAg composite

    Science.gov (United States)

    Pogacean, F.; Biris, A. R.; Socaci, C.; Floare-Avram, V.; Rosu, M. C.; Coros, M.; Pruneanu, S.

    2015-12-01

    Carbamazepine is a pharmaceutical drug which has been detected in surface and drinking water primarily due to human usage but also from the accidental disposal of pharmaceuticals into sewers. We have developed a graphene-modified electrode which was tested at the detection and degradation of carbamazepine. The oxidation process was studied by cyclic voltammetry in aqueous and organic solutions. The electrochemical degradation of carbamazepine was performed by polarizing the working electrode at a certain potential, for different times (from 5 to 60 minutes). The degradation efficiency was highly dependent on the type of solution and on the supporting electrolyte.

  19. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    Science.gov (United States)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  20. Factors determining the structure of Au, Ag and Cr thin layers deposited on alkaline halogen substrates

    International Nuclear Information System (INIS)

    Metal thin layer deposited on dielectric substrates, in general, and on alkaline halogen substrates, in particular, have been thoroughly studied in order to make clear the phenomenology of the formation and development processes, to set out fundamental factors in determining their structure and to determine optimum conditions for the obtaining of monocrystal thin layers or metastable structured thin layers in view of their practical applications. Starting from a systematic programme of experimental investigations, an attempt has been made to investigate the influence of substrate composition, of defects within alkaline halogen substrates and of deposition conditions on the orientated formation and development of Au layer and on the formation of metastable Cr-delta structures in the case of thin Cr layers. A systematic study on the influence of deposition conditions and on alkaline halogen substrates with colloidal centres is carried out in view of elaborating a method for the development of monocrystal Au layers for ''channeling targets''. A correlation between characteristic parameters which define the atomic theory of nucleation including deposition conditions and material parameters, Au parameters for the case of epitaxial layers deposited on KBr, KCl and NaCl substrates has been attempted. (author)

  1. Laser-Induced, Polarization Dependent Shape Transformation of Au/Ag Nanoparticles in Glass

    OpenAIRE

    Hofmeister H; Haug J; Dubiel M; Seifert G; Stalmashonak A

    2009-01-01

    Abstract Bimetallic, initially spherical Ag/Au nanoparticles in glass prepared by ion implantation have been irradiated with intense femtosecond laser pulses at intensities still below the damage threshold of the material surface. This high-intensity laser processing produces dichroism in the irradiated region, which can be assigned to the observed anisotropic nanoparticle shapes with preferential orientation of the longer particle axis along the direction of laser polarization. In addition, ...

  2. The DynAlloy Visualizer

    OpenAIRE

    Bendersky, Pablo; Galeotti, Juan Pablo; Garbervetsky, Diego

    2014-01-01

    We present an extension to the DynAlloy tool to navigate DynAlloy counterexamples: the DynAlloy Visualizer. The user interface mimics the functionality of a programming language debugger. Without this tool, a DynAlloy user is forced to deal with the internals of the Alloy intermediate representation in order to debug a flaw in her model.

  3. What Sexual Recidivism Rates Are Associated With Static-99R and Static-2002R Scores?

    Science.gov (United States)

    Hanson, R Karl; Thornton, David; Helmus, Leslie-Maaike; Babchishin, Kelly M

    2016-04-01

    Empirical actuarial risk tools are routinely used to assess the recidivism risk of adult sexual offenders. Compared with other forms of risk assessment, one advantage of actuarial risk tools is that they provide recidivism rate estimates. Previous research, however, suggests that there is considerable variability in the recidivism rates associated with the most commonly used sexual offender risk assessment tools (Static-99/R, Static-2002/R). The current study examined the extent to which the variability in the recidivism rates across 21 Static-99R studies (N = 8,805) corresponded to the normative groups proposed by the STATIC development group (routine, treatment, high risk/high need). We found strong evidence that routine (i.e., complete) samples were, on average, less likely to reoffend with a sexual offense than offenders in the high-risk/high-need samples (i.e., those explicitly preselected on risk-relevant variables external to STATIC scales). The differences between routine/complete and high-risk/high-need samples, however, were only consistently observed for offenders with low or moderate scores; for offenders with high STATIC scores, the 5-year sexual recidivism rates for these two groups were not meaningfully different. There was only limited evidence to support treatment samples as a distinct sample type; consequently, the use of separate normative tables for treatment samples is not recommended. The current results reinforce the value of regularly updating the norms for empirical actuarial risk tools. Options are discussed on how STATIC scores could be used to inform recidivism rates estimates in applied assessments. PMID:25810478

  4. The infrared behaviour of the static potential in perturbative QCD

    CERN Document Server

    Brambilla, Nora; Soto, J; Vairo, Antonio

    1999-01-01

    The definition of the quark-antiquark static potential is given within an effective field theory framework. The leading infrared divergences of the static singlet potential in perturbation theory are explicitly calculated.

  5. ARC Code TI: Inference Kernel for Open Static Analyzers (IKOS)

    Data.gov (United States)

    National Aeronautics and Space Administration — IKOS is a C++ library designed to facilitate the development of sound static analyzers based on Abstract Interpretation. Specialization of a static analyzer for an...

  6. Static Consistency Checking of Web Applications with WebDSL

    NARCIS (Netherlands)

    Hemel, Z.; Groenewegen, D.M.; Kats, L.C.L.; Visser, E.

    2010-01-01

    Modern web application development frameworks provide web application developers with highlevel abstractions to improve their productivity. However, their support for static verification of applications is limited. Inconsistencies in an application are often not detected statically, but appear as er

  7. Texture and stretch formability of AZ61 and AM60 magnesium alloy sheets processed by high-temperature rolling

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xinsheng, E-mail: huang-xs@aist.go.jp [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Aichi 463-8560 (Japan); Suzuki, Kazutaka; Chino, Yasumasa [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Aichi 463-8560 (Japan); Mabuchi, Mamoru [Graduate School of Energy Science, Kyoto University, Kyoto 606-8501 (Japan)

    2015-05-25

    Highlights: • High-temperature rolling and annealing results in a well-weakened basal texture. • The texture weakening is more significantly for AM60 alloy compared to AZ61 alloy. • The different recrystallization behavior is due to the effect of solute Zn atoms. • AZ61 and AM60 alloys exhibit the Erichsen values of 7.8 and 8.5 mm, respectively. • The higher Erichsen value for AM60 alloy is due to more weakened basal texture. - Abstract: AZ61 and AM60 magnesium alloys, with higher mechanical strengths than that of the most commonly used AZ31 alloy, were subjected to high-temperature rolling. Although the basal textures of the as-rolled sheets of both alloys were significantly weakened by annealing, the texture weakening was more significant in the latter than in the former. In addition, splitting of the basal pole was not retained after annealing for the AZ61 alloy, but this type of texture was preserved in the case of the AM60 alloy. The formation of statically recrystallized grains with dispersed orientations resulted in the aforementioned change in texture. The difference in the static recrystallization behavior could be attributed to the solute effect of zinc atoms. The annealed AZ61 and AM60 alloy sheets exhibited excellent stretch formability at room temperature, with Erichsen values of 7.8 and 8.5 mm, respectively, comparable to those of aluminum alloys. The higher Erichsen value for the AM60 alloy compared to that of the AZ61 alloy resulted from the more weakened basal texture and the splitting of the basal pole with an inclination angle of ±20° in the rolling direction, which are favorable for basal slip during sheet forming.

  8. Texture and stretch formability of AZ61 and AM60 magnesium alloy sheets processed by high-temperature rolling

    International Nuclear Information System (INIS)

    Highlights: • High-temperature rolling and annealing results in a well-weakened basal texture. • The texture weakening is more significantly for AM60 alloy compared to AZ61 alloy. • The different recrystallization behavior is due to the effect of solute Zn atoms. • AZ61 and AM60 alloys exhibit the Erichsen values of 7.8 and 8.5 mm, respectively. • The higher Erichsen value for AM60 alloy is due to more weakened basal texture. - Abstract: AZ61 and AM60 magnesium alloys, with higher mechanical strengths than that of the most commonly used AZ31 alloy, were subjected to high-temperature rolling. Although the basal textures of the as-rolled sheets of both alloys were significantly weakened by annealing, the texture weakening was more significant in the latter than in the former. In addition, splitting of the basal pole was not retained after annealing for the AZ61 alloy, but this type of texture was preserved in the case of the AM60 alloy. The formation of statically recrystallized grains with dispersed orientations resulted in the aforementioned change in texture. The difference in the static recrystallization behavior could be attributed to the solute effect of zinc atoms. The annealed AZ61 and AM60 alloy sheets exhibited excellent stretch formability at room temperature, with Erichsen values of 7.8 and 8.5 mm, respectively, comparable to those of aluminum alloys. The higher Erichsen value for the AM60 alloy compared to that of the AZ61 alloy resulted from the more weakened basal texture and the splitting of the basal pole with an inclination angle of ±20° in the rolling direction, which are favorable for basal slip during sheet forming

  9. The Effect of Pre-Stressing on the Static Indentation Load Capacity of the Superelastic 60NiTi

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2013-01-01

    Superelastic nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt.%), are under development for use in mechanical components like rolling element bearings and gears. Compared to traditional bearing steels, these intermetallic alloys, when properly heat-treated, are hard but exhibit much lower elastic modulus (approx.100 GPa) and a much broader elastic deformation range (approx.3 percent or more). These material characteristics lead to high indentation static load capacity, which is important for certain applications especially space mechanisms. To ensure the maximum degree of elastic behavior, superelastic materials must be pre-stressed, a process referred to as "training" in shape memory effect (SME) terminology, at loads and stresses beyond expected use conditions. In this paper, static indentation load capacity tests are employed to assess the effects of pre-stressing on elastic response behavior of 60NiTi. The static load capacity is measured by pressing 12.7 mm diameter ceramic Si3N4 balls into highly polished, hardened 60NiTi flat plates that have previously been exposed to varying levels of pre-stress (up to 2.7 GPa) to determine the load that results in shallow but measurable (0.6 m, 25 in. deep) permanent dents. Hertz stress calculations are used to estimate contact stress. Without exposure to pre-stress, the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.4 m deep) occurs. When pre-stressed to 2.7 GPa, a static load of 4900 kN is required to achieve a comparable dent, a 30 percent increase. These results suggest that stressing contact surfaces prior to use enhances the static indentation load capacity of the superelastic 60NiTi. This approach may be adaptable to the engineering and manufacture of highly resilient mechanical components such as rolling element bearings.

  10. Fabrication of superhydrophobic nanostructured surface on aluminum alloy

    Science.gov (United States)

    Jafari, R.; Farzaneh, M.

    2011-01-01

    A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon®) on the surface of an aluminum alloy substrate. Immersion in boiling water was used to create a micro-nanostructure on the alloy substrate. Then, the rough surface was coated with RF-sputtered Teflon film. The immersion time in boiling water plays an important role in surface morphology and water repellency of the deposited Teflon coating. Scanning electron microscopy images showed a "flower-like" structure in first few minutes of immersion. And as the immersion time lengthened, a "cornflake" structure appeared. FTIR analyses of Teflon-like coating deposited on water treated aluminum alloy surfaces showed fluorinated groups, which effectively reduce surface energy. The Teflon-like coating deposited on a rough surface achieved with five-minute immersion in boiling water provided a high static contact angle (˜164°) and low contact angle hysteresis (˜4°).

  11. Design, Analysis and Optimization of Three Aluminium Piston Alloys Using FEA

    Directory of Open Access Journals (Sweden)

    Ajay Raj Singh

    2014-01-01

    Full Text Available This paper describes the stress distribution and thermal stresses of three different aluminum alloys piston by using finite element method (FEM. The parameters used for the simulation are operating gas pressure, temperature and material properties of piston. The specifications used for the study of these pistons belong to four stroke single cylinder engine of Bajaj Kawasaki motorcycle. This paper illustrates the procedure for analytical design of three aluminum alloy pistons using specifications of four stroke single cylinder engine of Bajaj Kawasaki motorcycle. The results predict the maximum stress and critical region on the different aluminum alloy pistons using FEA. It is important to locate the critical area of concentrated stress for appropriate modifications. Static and thermal stress analysis is performed by using ANSYS 12.1. The best aluminum alloy material is selected based on stress analysis results. The analysis results are used to optimize piston geometry of best aluminum alloy.

  12. 30 CFR 56.6602 - Static electricity dissipation during loading.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Static electricity dissipation during loading... Explosives Extraneous Electricity § 56.6602 Static electricity dissipation during loading. When explosive material is loaded pneumatically into a blasthole in a manner that generates a static electricity...

  13. 14 CFR 27.610 - Lightning and static electricity protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk...

  14. Killing Vector Fields of Standard Static Space-times

    OpenAIRE

    Dobarro, Fernando; Unal, Bulent

    2008-01-01

    We consider Killing vector fields on standard static space-times and obtain equations for a vector field on a standard static space-time to be Killing. We also provide a characterization of Killing vector fields on standard static space-times with compact Riemannian parts.

  15. 14 CFR 23.177 - Static directional and lateral stability.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static directional and lateral stability. 23.177 Section 23.177 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Flight Stability § 23.177 Static directional and lateral stability. (a) The static directional...

  16. Suitability of Tophet C-Alloy 52/Kovar components to hydrogen environments

    International Nuclear Information System (INIS)

    The suitability of Tophet C-Alloy 52/Kovar weldments to hydrogen embrittlement were investigated because of their potential as candidate materials in fabrication of minaturized initiators for pyrotechnics. Cathodic charged samples were statically loaded for extended periods of time resulting in no load failures and in ductile fracture surfaces indicating resistance to hydrogen embrittlement. 20 figures

  17. Rapid, selective, and ultrasensitive fluorimetric analysis of mercury and copper levels in blood using bimetallic gold-silver nanoclusters with "silver effect"-enhanced red fluorescence.

    Science.gov (United States)

    Zhang, Ning; Si, Yanmei; Sun, Zongzhao; Chen, Lijun; Li, Rui; Qiao, Yuchun; Wang, Hua

    2014-12-01

    Bimetallic alloying gold-silver nanoclusters (Au-AgNCs) have been synthesized by a one-pot biomineralization synthesis route at a vital molar ratio of Au/Ag precursors in the protein matrix. Unexpectedly, the prepared Au-AgNCs could exhibit dramatically enhanced red fluorescence, which is about 6.5-fold and 4.7-fold higher than that of common AuNCs and core-shell Au@AgNCs, respectively. A rapid, selective, and ultrasensitive fluorimetric method has thereby been developed using Au-AgNCs as fluorescent probes toward the separate detections of Hg(2+) and Cu(2+) ions in blood. The interactions of Au-AgNCs with Hg(2+) and Cu(2+) ions were systematically characterized by microscopy imaging, UV-vis, and fluorescence measurements. It is demonstrated that the "silver effect" gives the Au-AgNCs probes not only greatly enhanced red fluorescence but also the strong capacity to specifically sense Cu(2+) ions in addition to improved response to Hg(2+) ions. Moreover, aided by a Cu(2+) chelating agent, exclusive detection of Hg(2+) ions could also be expected with the coexistence of a high level of Cu(2+) ions, as well as reversible Cu(2+) analysis by restoring the fluorescence of Au-AgNCs. Additionally, Au-AgNCs with strong red fluorescence could facilitate fluorimetric analysis with minimal interference from blood backgrounds. Such an Au-AgNCs-based fluorimetric method can allow for the selective analysis of Hg(2+) and Cu(2+) ions down to 0.30 nM and 0.60 nM in blood, respectively, promising a novel detection method to be applied in the clinical laboratory. PMID:25350497

  18. Palladium-chromium static strain gages for high temperatures

    Science.gov (United States)

    Lei, Jih-Fen

    1992-01-01

    An electrical resistance strain gage that can provide accurate static strain measurement to a temperature of 1500 F or above is being developed both in fine wire and thin film forms. The gage is designed to be temperature compensated on any substrate material. It has a dual element: the gage element is a special alloy, palladium-13wt percent chromium (PdCr), and the compensator element is platinum (Pt). Earlier results of a PdCr based wire gage indicated that the apparent strain of this gage can be minimized and the repeatability of the apparent strain can be improved by prestabilizing the gage on the substrate for a long period of time. However, this kind of prestabilization is not practical in many applications and therefore the development of a wire gage which is prestabilized before installation on the substrate is desirable. This paper will present our recent progress in the development of a prestabilized wire gage which can provide meaningful strain data for the first thermal cycle. A weldable PdCr gage is also being developed for field testing where conventional flame-spraying installation can not be applied. This weldable gage is narrower than a previously reported gage, thereby allowing the gage to be more resistant to buckling under compressive loads. Some preliminary results of a prestabilized wire gage flame-sprayed directly on IN100, an engine material, and a weldable gage spot-welded on IN100 and SCS-6/(beta)21-S Titanium Matrix Composite (TMC), a National Aero-Space Plane (NASP) structure material, will be reported. Progress on the development of a weldable thin film gage will also be addressed. The measurement technique and procedures and the lead wire effect will be discussed.

  19. Superplasticity in titanium alloys

    OpenAIRE

    J. Sieniawski; Motyka, M.

    2007-01-01

    Purpose: The paper reports characteristic of superplasticity phenomenon in titanium alloys and possibility of its applications.Design/methodology/approach: The main objective of the paper is to show features of superplastic forming of titanium alloys and current research trends aiming at widespread application of this technology.Findings: In the paper characteristic of selected superplastic titanium alloys was presented. The effect of microstructural parameters on superplasticity was consider...

  20. Corrosion resistant amorphous alloys

    International Nuclear Information System (INIS)

    A review of publication data on corrosion resistance of amorphous alloys and the methods of amorphization of surface layers of massive materials (laser treatment, iron implantation, detonation-gas spraying, cathode and ion sputtering, electrodeposition) was made. A study was made on corrosion properties of Fe66Cr11B10Si4 alloy in cast state and after laser irradiation, rendering the surface amorphous as well as the samples of Arenco iron and steel 20 with ion-plasma coatings of Fe-Cr-Ni-Ti alloy. It was established that amorphous coatings posses much higher corrosion resistance as compared to crystalline alloys on the same base

  1. Compact static stars in minimal dilatonic gravity

    CERN Document Server

    Fiziev, Plamen P

    2014-01-01

    We present the basic equations and relations for the relativistic static spherically symmetric stars (SSSS) in the model of minimal dilatonic gravity (MDG) which is {\\em locally} equivalent to the f(R) theories of gravity and gives an alternative description of the effects of dark matter and dark energy. The results for the simplest form of the relativistic equation of state (EOS) of neutron matter are represented. Our approach overcomes the well-known difficulties of the physics of SSSS in the f(R) theories of gravity introducing two novel EOS for cosmological energy-pressure densities and dilaton energy-pressure densities, as well as proper boundary conditions.

  2. Does Acute Static Stretching Reduce Muscle Power?

    Directory of Open Access Journals (Sweden)

    Francis M. Kozub

    2012-12-01

    Full Text Available Context: Stretching is commonly used as a technique for injury prevention in the training and clinical setting. Recently, stretching in the warm-up has been shown to decrease several muscular performance variables, but the dose-response of this effect is unknown and moreover these stretching bouts are not representative of athletes during warm up procedures, as they are usually time consuming. Our findings may improve the understanding of the neuromuscular responses to stretching and help sportsmen, coaches, physiotherapist and clinicians make decisions for integrating stretching as a part of warm up or rehabilitation treatment plan.Purpose: The aim of the present study was to examine whether acute static stretching is responsible for losses in isokinetic peak torque production and if it does, than which time of stretching effect muscle peak torque?Design: Randomized, counterbalanced, within-subjects experimental design.Setting: A university human project laboratory.Methods: Twenty (n=20 light to moderate young exercisers, male and female, from University of Limerick community, with an average age of 22.1±3.6 years, height of 175.6±5 cm, and weight of 73.1±9.9 kg, were randomly selected to take part in the study. Prior to the main study, volunteers attended the lab on two occasions to be familiarized with the knee extension protocol on the Con - trex isokinetic system and with the static stretching protocol. All participants than performed five additional static stretching protocols randomly, in non-consecutive training session. The stretching protocols were 0, 60,120, 180 and 180 with alternative pattern.Results: The results of the statistical analysis (P > 0.05 indicated that peak torque remained unchanged following the static stretching for 0-180 sec at 60 & 180° s−1 angular velocities.Conclusion: The findings suggest that an athletic stretching (shorter duration ranging from 0-180 sec does not produce decreases in peak torque. Athletes

  3. Static-light meson-meson potentials

    CERN Document Server

    Bali, Gunnar

    2010-01-01

    We investigate potentials between pairs of static-light mesons in Nf=2 Lattice QCD, in different spin channels. The question of attraction and repulsion is particularly interesting with respect to the X(3872) charmonium state and charged candidates such as the Z+(4430). We employ the nonperturbatively improved Sheikholeslami-Wohlert fermion and the Wilson gauge actions at a lattice spacing a approx. 0.084 fm and a pseudoscalar mass mPS approx. 760 MeV. We use stochastic all-to-all propagator techniques, improved by a hopping parameter expansion. The analysis is based on the variational method, utilizing various source and sink interpolators.

  4. STATIC AND DYNAMIC THEORIES OF LIQUID CRYSTALS

    Institute of Scientific and Technical Information of China (English)

    林芳华; 刘春

    2001-01-01

    The study of liquid crystals givesrise to many fascinating but difficult mathematical problems. The purpose of this paper is to briefly summarize some recent advances, as well as to describe the present state of art of the theory of liquid crystals.For the static theory, we emphasis on the theory of defects and the theory of Smectic A materials. We will also study the Ericksen-Leslie theory for the liquid crystal flow.The well-posedness as well as the motion of the defects will be discussed.

  5. Statics and dynamics of fluids in nanotubes

    CERN Document Server

    Gouin, Henri

    2013-01-01

    The purpose of this article is to study the statics and dynamics of nanotubes by using the methods of continuum mechanics. The nanotube can be filled with only a liquid or a vapour phase according to the physicochemical characteristics of the wall and to the disjoining pressure associated with the liquid and vapour mother bulks of the fluid, regardless of the nature of the external mother bulk. In dynamics, flows through nanotubes can be much more important than classical Poiseuille flows. When the external mother bulk is of vapour, the flow can be a million times larger than the classical flows when slippage on wall does not exist.

  6. Oxidation of zircaloy-4 under static conditions

    International Nuclear Information System (INIS)

    Static autoclave oxidation of zircaloy-4 at 543 K and 8.5 MPa is studied. Deviations from the straight line in kinetics curve are observed. White spots appear on the surface of the specimen even in the 'pre-transion' region. The existing theories cannot explain these observations. It is suggested that these deviations may be partly arising due to the variations in the processing parameters and impurities in zircaloy-4. Scanning electron micrography has been used to study the oxide coating after autoclave exposure of zircaloy-4 surface. (M.G.B.)

  7. Static analysis of software the abstract interpretation

    CERN Document Server

    Boulanger, Jean-Louis

    2013-01-01

    The existing literature currently available to students and researchers is very general, covering only the formal techniques of static analysis. This book presents real examples of the formal techniques called ""abstract interpretation"" currently being used in various industrial fields: railway, aeronautics, space, automotive, etc. The purpose of this book is to present students and researchers, in a single book, with the wealth of experience of people who are intrinsically involved in the realization and evaluation of software-based safety critical systems. As the authors are people curr

  8. Static Consensus in Passifiable Linear Networks

    Directory of Open Access Journals (Sweden)

    Ibragim A. Junussov

    2016-01-01

    Full Text Available Sufficient conditions of consensus (synchronization in networks described by digraphs and consisting of identical deterministic SIMO systems are derived. Identical and nonidentical control gains (positive arc weights are considered. Connection between admissible digraphs and nonsmooth hypersurfaces (sufficient gain boundary is established. Necessary and sufficient conditions for static consensus by output feedback in networks consisting of certain class of double integrators are rediscovered. Scalability for circle digraph in terms of gain magnitudes is studied. Examples and results of numerical simulations are presented.

  9. Static and Dynamic Criticality: Are They Different?

    International Nuclear Information System (INIS)

    Let us start by stating that this paper does not contain anything new. It only contains material that has been known for decades, but which is periodically forgotten. As such this paper is intended merely to refresh people's memories. We will also mention that this paper is an example of the occasional discrepancy between textbook methodologies and real world applications, in the sense that the conclusions reached here contradict what it says in most textbooks, i.e., most textbooks incorrectly interpret the methods presented here, particularly with respect to the use of importance sampling to maintain population control. This paper is not intended as a general tutorial on criticality calculations. It is intended only to clarify the accuracy of various methods for solving criticality problems, such as a true time dependent dynamic calculation, versus an alpha or K static calculation. In particular, we address the long standing controversy between users of the TART code [1] with the dynamic method, and users of the MCNP code [2] with the alpha static method. In this paper we will prove which methods are accurate and inaccurate

  10. On static Poincar\\'e-Einstein metrics

    CERN Document Server

    Galloway, Gregory J

    2015-01-01

    The classification of solutions of the static vacuum Einstein equations, on a given closed manifold or an asymptotically flat one, is a long-standing and much-studied problem. Solutions are characterized by a complete Riemannian $n$-manifold $(M,g)$ and a positive function $N$, called the lapse. We study this problem on Asymptotically Poincar\\'e-Einstein $n$-manifolds, $n\\ge 3$, when the conformal boundary-at-infinity is either a round sphere, a flat torus or smooth quotient thereof, or a compact hyperbolic manifold. Such manifolds have well-defined Wang mass, and are time-symmetric slices of static, vacuum, asymptotically anti-de Sitter spacetimes. By integrating a mildly generalized form of an identity first found by Wang, we give a mass formula for such manifolds. There are no solutions with positive mass. In consequence, we observe that either the lapse is trivial and $(M,g)$ is Poincar\\'e-Einstein or the Wang mass is negative, as in the case of time symmetric slices of the AdS soliton. As an application,...

  11. Static Deadlock Detection in MPI Synchronization Communication

    CERN Document Server

    Ming-Xue, Liao; Zhi-Hua, Fan

    2007-01-01

    It is very common to use dynamic methods to detect deadlocks in MPI programs for the reason that static methods have some restrictions. To guarantee high reliability of some important MPI-based application software, a model of MPI synchronization communication is abstracted and a type of static method is devised to examine deadlocks in such modes. The model has three forms with different complexity: sequential model, single-loop model and nested-loop model. Sequential model is a base for all models. Single-loop model must be treated with a special type of equation group and nested-loop model extends the methods for the other two models. A standard Java-based software framework originated from these methods is constructed for determining whether MPI programs are free from synchronization communication deadlocks. Our practice shows the software framework is better than those tools using dynamic methods because it can dig out all synchronization communication deadlocks before an MPI-based program goes into runni...

  12. Static Code Analysis with Gitlab-CI

    CERN Document Server

    Datko, Szymon Tomasz

    2016-01-01

    Static Code Analysis is a simple but efficient way to ensure that application’s source code is free from known flaws and security vulnerabilities. Although such analysis tools are often coming with more advanced code editors, there are a lot of people who prefer less complicated environments. The easiest solution would involve education – where to get and how to use the aforementioned tools. However, counting on the manual usage of such tools still does not guarantee their actual usage. On the other hand, reducing the required effort, according to the idea “setup once, use anytime without sweat” seems like a more promising approach. In this paper, the approach to automate code scanning, within the existing CERN’s Gitlab installation, is described. For realization of that project, the Gitlab-CI service (the “CI” stands for "Continuous Integration"), with Docker assistance, was employed to provide a variety of static code analysers for different programming languages. This document covers the gene...

  13. Thermofluency in zirconium alloys

    International Nuclear Information System (INIS)

    A summary is presented about the theoretical and experimental results obtained at present in thermofluency under radiation in zirconium alloys. The phenomenon of thermofluency is presented in a general form, underlining the thermofluency at high temperature because this phenomenon is similar to the thermofluency under radiation, which ocurrs in zirconium alloys into the operating reactor. (author)

  14. High temperature niobium alloys

    International Nuclear Information System (INIS)

    Niobium alloys are currently being used in various high temperature applications such as rocket propulsion, turbine engines and lighting systems. This paper presents an overview of the various commercial niobium alloys, including basic manufacturing processes, properties and applications. Current activities for new applications include powder metallurgy, coating development and fabrication of advanced porous structures for lithium cooled heat pipes

  15. Ultrahigh temperature intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  16. Alloys in energy development

    International Nuclear Information System (INIS)

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems

  17. Brazing with plated alloys

    International Nuclear Information System (INIS)

    The use of braze alloy preforms on complex geometry components is at times a very difficult task requiring extensive handling of the parts or even tack welding of the preform to ensure that it is held in place. One method of overcoming these difficulties is the use of plated braze alloys (i.e., filler metals) applied directly to the braze region. Plating helps to avoid the potential for contamination resulting from handling and also ensures that the braze alloy is located properly. Examples are discussed in which an electroplated silver-copper alloy is used as an alternative to the BAg8 preforms and electroless nickel is used as a replacement for an amorphous Ni-P braze alloy foil. A toroidal cooling plate with helical flow channels was fabricated from oxygen-free high conductivity (OFHC) and brazed using the electroplated silver-copper alloy. The silver-copper braze alloy was applied to the copper substrate in a laminated fashion of alternating layers of silver and copper, which in combination approximated the eutectic composition (72% Ag-28% Cu by weight). Examination of the brazed assemblies indicated that in both cases the advantages of using plated braze alloys are numerous. These advantages include decreased labor, improved cleanliness and exactness of braze alloy placement. The primary disadvantage was an increased tendency for solidification defects presumably resulting from contaminants in the plating baths. This last observation is presently being examined in greater detail. The end results is that the assemblies brazed with the plated alloys were acceptable for the intended application and that the use of plating facilitated the successful assembly of these components

  18. Static Fatigue of Optical Fibers in Bending

    Science.gov (United States)

    Roberts, D.; Cuellar, E.; Middleman, L.; Zucker, J.

    1987-02-01

    While delayed fracture, or static fatigue, of optical fibers is well known, it is not well understood, and the prediction of the time to failure under a given set of conditions can be problematic. Unlike short term fracture, which is quite well understood and quantified in terms of the theory of linear elastic fracture mechanics, the long term strength remains empirical. The goal of this study is to determine the design criteria for optical fibers subjected to long term applied mechanical loads. One difficulty in making lifetime predictions, as pointed out by Matthewson (Reference 1) and others, is that predictions made from data taken in tension and in bending do not agree. Another difficulty is the statistical nature of the fracture of glass. In making lifetime predictions it becomes important therefore that one (a) have ample data for statistical analysis and (b) have data for the loading configuration of interest. This is the purpose of our work. Since there is less data available in bending, and since several applications (such as wiring in aircraft and missiles) require bending, the data are taken in that configuration. The most significant finding in our work so far is the very large difference in static fatigue behavior between buffer coatings. Chandan and Kalish (Reference 2) and others have reported static fatigue curves, log (time to failure) versus log (applied stress), which are not linear, but rather bimodal. Our study confirms this result, but so far only for acrylate coated fibers. Silicone coated fibers show unimodal behavior. That is, the log (time to failure) versus log (applied stress) curve is linear, at least on the time scale studied so far. Data for acrylate coated fibers at 80°C in water are linear only for time scales of about one day, where a pronounced "knee" is observed. Data for silicone coated fibers under the same conditions are linear up to at least 6 months. Longer time scale tests and tests on fibers with other buffer materials

  19. Magnetic properties of ball-milled nanocrystalline alloys Fe sub 7 sub 8 B sub 1 sub 3 Si sub 9

    CERN Document Server

    Pekala, M; Jachimowicz, M

    2002-01-01

    Magnetic properties of nanocrystalline Fe sub 7 sub 8 B sub 1 sub 3 Si sub 9 alloys are studied for three series prepared by ball milling starting from amorphous ribbons, crystallized ribbons, and elemental powders. Temperature variation of static magnetization results in strong ferromagnetic interaction which is weakly dependent on the initial material. Magnetic hysteresis loops show that saturation magnetization, magnetic remanence, and coercive field increase with frequency for both series of ribbon samples, whereas they decrease for alloys prepared from elemental powders. Power losses raise faster for the alloys prepared from elemental powders than for the two other alloys. (author)

  20. An evaluation of corrosion characteristics of materials for cladding (Zr) and heat-exchanger tubes (Ti) of SMART in static autoclaves

    International Nuclear Information System (INIS)

    The corrosion characteristics of materials (Low-Sn Zircaloy-4, Zr-1.0Nb, PT-7M, ASTM Gr. 2 Ti, Inconel-600 alloys) for cladding and heat-exchanger tubes of SMART in pure water, ammonia aqueous solutions of pH 9.98 and pH 11.13 at 360 .deg. and in steam at 400 .deg. were evaluated by using static autoclaves

  1. Static dielectric properties of dense ionic fluids.

    Science.gov (United States)

    Zarubin, Grigory; Bier, Markus

    2015-05-14

    The static dielectric properties of dense ionic fluids, e.g., room temperature ionic liquids (RTILs) and inorganic fused salts, are investigated on different length scales by means of grandcanonical Monte Carlo simulations. A generally applicable scheme is developed which allows one to approximately decompose the electric susceptibility of dense ionic fluids into the orientation and the distortion polarization contribution. It is shown that at long range, the well-known plasma-like perfect screening behavior occurs, which corresponds to a diverging distortion susceptibility, whereas at short range, orientation polarization dominates, which coincides with that of a dipolar fluid of attached cation-anion pairs. This observation suggests that the recently debated interpretation of RTILs as dilute electrolyte solutions might not be simply a yes-no-question but it might depend on the considered length scale. PMID:25978895

  2. Axially symmetric static sources of gravitational field

    CERN Document Server

    Hernandez-Pastora, J L; Martin, J

    2016-01-01

    A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match smoothly to some exterior solution of the Weyl family, thereby representing globally regular models describing non spherical sources of gravitational field. In the spherically symmetric limit, all our models converge to the well known incompressible perfect fluid solution.The key stone of our approach is based on an ansatz allowing to define the interior metric in terms of the exterior metric functions evaluated at the boundary source. Some particular sources are obtained, and the physical variables of the energy-momentum tensor are calculated explicitly, as well as the geometry of the source in terms of the relativistic multipole moments. The total mass of different configurations is also calculated, it is shown to be equal to the monopole of the exterior solution.

  3. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  4. Soil stress state determination under static load

    Directory of Open Access Journals (Sweden)

    D. Błażejczak

    1995-09-01

    Full Text Available Intensification of crop production by uncontrolled increasing use of agricultural machinery negatively affects soil physical properties. Heavy machinery traffic causes soil compaction, erosion and physical degradation. In this study soil stress state under static vertical loading was predicted as a function of increasing load, soil tillage variants (plough and rototiller as well as soil structure. Monolith samples were investigated using a SST transducer and a deformation measure device. The investigations were carried out in an Ap horizon of sandy loam Luvisol derived from glacial till (site Hohenschulen, nearby Kiel, Germany, for two tillage and structure variants. The three major stresses, octahedral shear stress and its angle, mean normal stress as the complete stress state were determined using the SST transducer system. Soil deformations and bulk density changes were also investigated. Effects of soil structure and tillage on stress state were predicted.

  5. Static hand gesture recognition from a video

    Science.gov (United States)

    Rokade, Rajeshree S.; Doye, Dharmpal

    2011-10-01

    A sign language (also signed language) is a language which, instead of acoustically conveyed sound patterns, uses visually transmitted sign patterns to convey meaning- "simultaneously combining hand shapes, orientation and movement of the hands". Sign languages commonly develop in deaf communities, which can include interpreters, friends and families of deaf people as well as people who are deaf or hard of hearing themselves. In this paper, we proposed a novel system for recognition of static hand gestures from a video, based on Kohonen neural network. We proposed algorithm to separate out key frames, which include correct gestures from a video sequence. We segment, hand images from complex and non uniform background. Features are extracted by applying Kohonen on key frames and recognition is done.

  6. Distributed parameter statics of magnetic catheters.

    Science.gov (United States)

    Tunay, Ilker

    2011-01-01

    We discuss how to use special Cosserat rod theory for deriving distributed-parameter static equilibrium equations of magnetic catheters. These medical devices are used for minimally-invasive diagnostic and therapeutic procedures and can be operated remotely or controlled by automated algorithms. The magnetic material can be lumped in rigid segments or distributed in flexible segments. The position vector of the cross-section centroid and quaternion representation of an orthonormal triad are selected as DOF. The strain energy for transversely isotropic, hyperelastic rods is augmented with the mechanical potential energy of the magnetic field and a penalty term to enforce the quaternion unity constraint. Numerical solution is found by 1D finite elements. Material properties of polymer tubes in extension, bending and twist are determined by mechanical and magnetic experiments. Software experiments with commercial FEM software indicate that the computational effort with the proposed method is at least one order of magnitude less than standard 3D FEM. PMID:22256282

  7. Static Leaching of Spanish Uranium Ores

    International Nuclear Information System (INIS)

    The paper summarizes the experience acquired in Spain during seven years of investigation on the static leaching of uranium ores. The operations covered minerals showing wide variations with regard to both uranium content (250 and 2000 ppm) and the type of rock and gangue (granites, shales, sandstones, sulphides, carbonates, limonites etc. ). The studies were carried out on quantities of material varying from a few kilograms to several tons. Leaching agents included water, solid reagents (pyrites), alkaline carbonates and sulphuric acid. The systems used consisted of both simple layouts and other, more elaborate schemes including recycling of the liquors. The uranium was recovered from the liquors first by direct precipitation and later by ion-exchange and extraction with amines. (author)

  8. Static leaching of Spanish uranium ores

    International Nuclear Information System (INIS)

    The paper summarizes the experience acquired in Spain during seven years of investigation on the static leaching of uranium ores. The operations covered minerals showing wide variations with regard to both uranium content (250 and 2000 ppm) and the type of rock and gangue (granites, shales, sandstones, sulphides, carbonates, limonites etc.). The studies were carried out on quantities of material varying from a few kilograms to several tons. Leaching agents included water, solid reagents (pyrites), alkaline carbonates and sulphuric acid. The systems used consisted of both simple layouts and other, more elaborate schemes including recycling of the liquors. The uranium was recovered from the liquors first by direct precipitation and later by ion-exchange and extraction with amines. (author)

  9. Multipoint vibrometry with dynamic and static holograms

    Energy Technology Data Exchange (ETDEWEB)

    Haist, T.; Lingel, C.; Osten, W. [Institut für Technische Optik, Stuttgart Research Center of Photonic Engineering (SCOPE), University of Stuttgart, D-70569 Stuttgart (Germany); Winter, M.; Giesen, M.; Ritter, F.; Sandfort, K.; Rembe, C. [Polytec GmbH, Polytec-Platz 1-7, D-76337 Waldbronn (Germany); Bendel, K. [Corporate Sector Research and Advanced Engineering, Robert Bosch GmbH, Gerlingen (Germany)

    2013-12-15

    We report on two multipoint vibrometers with user-adjustable position of the measurement spots. Both systems are using holograms for beam deflection. The measurement is based on heterodyne interferometry with a frequency difference of 5 MHz between reference and object beam. One of the systems uses programmable positioning of the spots in the object volume but is limited concerning the light efficiency. The other system is based on static holograms in combination with mechanical adjustment of the measurement spots and does not have such a general efficiency restriction. Design considerations are given and we show measurement results for both systems. In addition, we analyze the sensitivity of the systems which is a major limitation compared to single point scanning systems.

  10. FACET Tolerances for Static and Dynamic Misalignments

    Energy Technology Data Exchange (ETDEWEB)

    Federico, Joel

    2012-07-13

    The Facility for AdvancedAccelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 {micro}m x 10 {micro}m in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed.

  11. Static Isotropic Spacetimes with Radially Imperfect Fluids

    CERN Document Server

    Konopka, Tomasz

    2009-01-01

    When solving the equations of General Relativity in a symmetric sector, it is natural to consider the same symmetry for the geometry and stress-energy. This implies that for static and isotropic spacetimes, the most general natural stress-energy tensor is a sum of a perfect fluid and a radial imperfect fluid component. In the special situations where the perfect fluid component vanishes or is a spacetime constant, the solutions to Einstein's equations can be thought of as modified Schwarzschild and Schwarzschild-de Sitter spaces. Exact solutions of this type are derived and it is shown that whereas deviations from the unmodified solutions can be made small, among the manifestations of the imperfect fluid component is a shift in angular momentum scaling for orbiting test-bodies at large radius. Based on this effect, the question of whether the imperfect fluid component can feasibly describe dark matter phenomenology is addressed.

  12. Network Completion for Static Gene Expression Data

    Directory of Open Access Journals (Sweden)

    Natsu Nakajima

    2014-01-01

    Full Text Available We tackle the problem of completing and inferring genetic networks under stationary conditions from static data, where network completion is to make the minimum amount of modifications to an initial network so that the completed network is most consistent with the expression data in which addition of edges and deletion of edges are basic modification operations. For this problem, we present a new method for network completion using dynamic programming and least-squares fitting. This method can find an optimal solution in polynomial time if the maximum indegree of the network is bounded by a constant. We evaluate the effectiveness of our method through computational experiments using synthetic data. Furthermore, we demonstrate that our proposed method can distinguish the differences between two types of genetic networks under stationary conditions from lung cancer and normal gene expression data.

  13. Gravitational vacuum polarization around static spherical stars

    International Nuclear Information System (INIS)

    The gravitational vacuum polarization of conformally coupled quantum fields in the spacetime of a uniform-density, static, spherical star is studied using the approximation developed by Page, Brown, and Ottewill. Approximate vacuum stress-energy tensors are calculated for conformal massless scalar, spinor, and vector fields; in the case of vector fields, both dimensionally regularized and zeta-function results are given. Explicit algebraic forms for the stress-energy tensors are given for the interior of the star and for the exterior Schwarzschild region. If the vacuum stress energy is to be conserved and have the correct trace anomaly at the surface of the star, it is necessary that there be distributional terms in the vacuum stress energy at the surface. The nature and magnitude of these terms are determined. The semiclassical Einstein equations are solved in the exterior region of the star to first order in (h/2π), and the first quantum corrections to Kepler's third law are found

  14. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅰ): Static flow resistance

    Institute of Scientific and Technical Information of China (English)

    LU TianJian; M.KEPETS; A.P.DOWLING

    2008-01-01

    Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAIY) foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and strength. In this work, the low-Reynolds number fluid properties of FeCrAIY foams were investigated both theoretically and experimen-tally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow. Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.

  15. Assessing Static Performance of the Dashengguan Yangtze Bridge by Monitoring the Correlation between Temperature Field and Its Static Strains

    Directory of Open Access Journals (Sweden)

    Gao-Xin Wang

    2015-01-01

    Full Text Available Taking advantage of the structural health monitoring system installed on the steel truss arch girder of Dashengguan Yangtze Bridge, the temperature field data and static strain data are collected and analyzed for the static performance assessment of the bridge. Through analysis, it is found that the static strain changes are mainly caused by temperature field (temperature and temperature difference and train. After the train-induced static strains are removed, the correlation between the remaining static strains and the temperature field shows apparent linear characteristics, which can be mathematically modeled for the description of static performance. Therefore, multivariate linear regression function combined with principal component analysis is introduced to mathematically model the correlation. Furthermore, the residual static strains of mathematical model are adopted as assessment indicator and three kinds of degradation regulations of static performance are obtained after simulation of the residual static strains. Finally, it is concluded that the static performance of Dashengguan Yangtze Bridge was in a good condition during that period.

  16. Corrosion of alloy D9 in liquid sodium

    International Nuclear Information System (INIS)

    Alloy D9 (15Cr-15Ni-Mo-Ti-Si) is chosen as clad and wrapper material for 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam. The successful operation of the reactor depends on the compatibility of the core structural materials such as clad and wrapper which are subject to high neutron irradiation and in contact with high temperature liquid sodium. The chemical compatibility of sodium with the core structural materials is generally good when the sodium is in the pure state. One of the major criteria for selection of clad and wrapper materials is corrosion in liquid sodium environment. The corrosion of alloy D9 in presence of sodium was studied at different temperatures (773, 798, 823 and 873 K) for various duration of time ranging from 1000 to 3000 h in a well characterized sodium loop. The observed corrosion data such as weight loss, depleted layer formation, changes in microstructure of the alloy D9 specimens are compared with the literature data available on sodium corrosion in static and dynamic conditions. The corrosion rates in dynamic and static sodium are comparable in the measured temperatures as the purity of sodium with respect to oxygen concentration is comparable. The corrosion rate is faster at higher temperature and for longer duration of exposure to liquid sodium. Loss of thickness of material at 873 K is < 5 μm per year. Exposure to sodium causes selective dissolution of alloying elements such as nickel and chromium. The metal losses, thickness of corroded layers and changes in chemical composition were only marginal at a maximum temperature of 873 K. Hence alloy D9 is a good choice for clad and wrapper tube material. (author)

  17. Studies on the growth of oxide films on alloy 800 and alloy 600 in lithiated water at high temperature

    International Nuclear Information System (INIS)

    In this work, the oxide films grown on Alloy 800 and Alloy 600 in lithiated (pH25Cdegrees = 10.2-10.4) water at high temperature, with and without hydrogen overpressure (HO) and an initial oxygen dissolved in the water have been studied. The oxide films were grown at different temperatures (220-350 C degrees) and exposure times with HO, and at 315 C degrees without HO in static autoclaves. Some results are also reported for oxide layers grown on Alloy 800 coupons exposed in a high temperature loop during extended exposure times. The average oxide thickness was determined using descaling procedures. The morphology and composition of the oxide films were analyzed with scanning electron microscopy (SEM), EDS and X-ray diffraction (XRD). For both Alloys, at 350 C degrees with HO, the oxide layers were clearly composed of a double layer: an inner one of very small crystallites and an outer layer formed by bigger crystals scattered over the inner one. The analysis by X-ray diffraction indicated the presence of spinel structures like magnetite (Fe3O4) and ferrites and/or nickel chromites. In this case the average oxide thickness was around 0.12 to 0.15 μm for both Alloys. Similar values were found at lower temperatures. The morphology of the oxide layer was similar at lower temperatures for Alloy 800, but a different morphology consisting of platelets or needles was found for Alloy 600. The oxide morphology found at 315 C degrees, without HO and with initial dissolved oxygen in the water, was also very different between both Alloys. The oxide film grown on Alloy 600 with an initial dissolved oxygen in the water, showed clusters of platelets forming structures like flowers that were dispersed on an rather homogeneous layer consisting of smaller platelets or needles. The average oxide film grown in this case was around 0.25 μm for Alloy 600 and 0.18 μm for Alloy 800. (author)

  18. Quasi-Static and Dynamic Tensile Properties of Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    Wojtaszek M.

    2013-12-01

    Full Text Available Stop Ti-6A1-4V jest szeroko stosowany głównie w przemyśle lotniczym ze względu na niski ciężar właściwy, dużą odpor- ność na korozję oraz wysokie własności mechaniczne. Ze względu na stosunkowo małą podatność do odkształceń plastycznych stopu Ti-6A1-4V. kształtowanie części o skomplikowanej geometrii z tego stopu wymaga bardzo dokładnego doboru warun- ków przeróbki cieplno-mechanicznej. W warunkach przemysłowych stop ten jest najczęściej kształtowany w procesach kucia lub wyciskania, które charakteryzują się różnymi zakresami prędkości odkształcania wsadu. Zastosowanie stopu Ti-6A1-4V obejmuje w dużej mierze wytwarzanie odpowiedzialnych elementów konstrukcji lotniczych, które są eksponowane na zmienne obciążenia w warunkach wysokich lub cyklicznie zmiennych prędkości, oraz które często muszą charakteryzować się doskona- łymi parametrami balistycznymi. Dlatego istotna w przypadku przedmiotowego materiału jest znajomość charakterystyk jego zachowania w warunkach obciążeń dynamicznych. Zauważyć można, że w odróżnieniu od danych otrzymanych w statycznych warunkach, ilość publikowanych informacji na ten temat jest niewielka. W pracy przeprowadzono próby jednoosiowego roz- ciągania próbek ze stopu Ti-6A1-4V, które prowadzono przy dużych prędkościach odkształcenia oraz, celem porównania, w warunkach quasi-statycznych. Do analizy wykorzystano system do bezkontaktowych trójwymiarowych pomiarów odkształceń ARAMIS. Badano wpływ prędkości odkształcenia na wybrane własności mechaniczne stopu, obserwacji i analizie poddano także powstałe podczas realizacji próby rozciągania powierzchnie zniszczenia.

  19. Dynamic compressive behavior of Pr-Nd alloy at high strain rates and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huanran; Cai Canyuan; Chen Danian [Mechanics and Materials Science Research Center, Ningbo University, Ningbo, Zhejiang 315211 (China); Ma Dongfang [Mechanics and Materials Science Research Center, Ningbo University, Ningbo, Zhejiang 315211 (China); School of Civil Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000 (China)

    2012-07-01

    Based on compressive tests, static on 810 material test system and dynamic on the first compressive loading in split Hopkinson pressure bar (SHPB) tests for Pr-Nd alloy cylinder specimens at high strain rates and temperatures, this study determined a J-C type [G. R. Johnson and W. H. Cook, in Proceedings of Seventh International Symposium on Ballistics (The Hague, The Netherlands, 1983), pp. 541-547] compressive constitutive equation of Pr-Nd alloy. It was recorded by a high speed camera that the Pr-Nd alloy cylinder specimens fractured during the first compressive loading in SHPB tests at high strain rates and temperatures. From high speed camera images, the critical strains of the dynamic shearing instability for Pr-Nd alloy in SHPB tests were determined, which were consistent with that estimated by using Batra and Wei's dynamic shearing instability criterion [R. C. Batra and Z. G. Wei, Int. J. Impact Eng. 34, 448 (2007)] and the determined compressive constitutive equation of Pr-Nd alloy. The transmitted and reflected pulses of SHPB tests for Pr-Nd alloy cylinder specimens computed with the determined compressive constitutive equation of Pr-Nd alloy and Batra and Wei's dynamic shearing instability criterion could be consistent with the experimental data. The fractured Pr-Nd alloy cylinder specimens of compressive tests were investigated by using 3D supper depth digital microscope and scanning electron microscope.

  20. Static characterization of the antiferromagnetic-to-ferromagnetic phase transition of FeRh thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramm, Paul; Radu, Ilie; Weber, Alexander; Back, Christian [Institut fuer Angewandte und Experimentelle Physik, Universitaet Regensburg (Germany); Stamm, Christian; Kachel, Torsten; Pontius, Niko; Duerr, Hermann [BESSY GmbH, Berlin (Germany); Raabe, Joerg; Quitmann, Christoph; Joly, Luiic [Paul Scherrer Institut, Villigen PSI (Switzerland); Thiele, Jan-Ulrich [Hitachi Global Storage Technologies, San Jose Research Center (United States)

    2007-07-01

    The antiferromagnetic-to-ferromagnetic phase transition present on the FeRh thin film alloy is studied by employing static magneto-optic Kerr effect (MOKE), X-ray magnetic circular dichroism (XMCD) and X-ray photoemission electron microscopy (XPEEM) techniques, which give information on the average magnetization, the element-specific magnetic moments as well as the domain structure, respectively. The element-specific hysteresis provided by the XMCD measurements near the transition temperature reveal the growth of the Fe magnetic moment and development of the small but crucial induced Rh magnetic moment in the ferromagnetic phase. Using temperature dependent XPEEM in the vicinity of the phase transition we observe the formation and the partial reproducibility of the magnetic domain structure. The temperature hysteresis of the magnetic contrast deduced from the XPEEM data is in good agreement with the temperature dependent MOKE measurements.

  1. Supporting secure programming in web applications through interactive static analysis

    OpenAIRE

    Jun Zhu; Jing Xie; Heather Richter Lipford; Bill Chu

    2013-01-01

    Many security incidents are caused by software developers’ failure to adhere to secure programming practices. Static analysis tools have been used to detect software vulnerabilities. However, their wide usage by developers is limited by the special training required to write rules customized to application-specific logic. Our approach is interactive static analysis, to integrate static analysis into Integrated Development Environment (IDE) and provide in-situ secure programming support to hel...

  2. The relationship between parameters of static and dynamic stability tests

    OpenAIRE

    Mohammad Taghi Karimi; Stephan Solomonidis

    2011-01-01

    Background: Stability is often described to be static (quiet standing) and dynamic (maintaining a stable position while undertake a prescribed movement). Many researchers have used only static tests to evaluate the stability of normal and handicapped subjects. However, it is important to evaluate the stability of subjects while undertaking various tasks (dynamic stability). It is not currently clear whether static balance can predict dynamic balance or not. Therefore, the aim of this research...

  3. The relationship between parameters of static and dynamic stability tests

    OpenAIRE

    Karimi, Mohammad Taghi; Solomonidis, Stephan

    2011-01-01

    BACKGROUND: Stability is often described to be static (quiet standing) and dynamic (maintaining a stable position while undertake a prescribed movement). Many researchers have used only static tests to evaluate the stability of normal and handicapped subjects. However, it is important to evaluate the stability of subjects while undertaking various tasks (dynamic stability). It is not currently clear whether static balance can predict dynamic balance or not. Therefore, the aim of this research...

  4. Static and Motional Feedthrough Capacitance of Flexural Microresonator

    OpenAIRE

    Wen-Teng Chang

    2011-01-01

    The present paper evaluates the static and motional feedthrough capacitance of a silicon carbide-based flexural-mode microelectromechanical system resonator. The static feedthrough capacitance was measured by a network analyzer under atmospheric pressure. The motional feedthrough was obtained by introducing various values into the modeling circuit in order to fit the Bode plots measured under reduced pressure. The static feedthrough capacitance was 0.02 pF, whereas the motional feedthrough ca...

  5. Optimality Conditions for Static Programming with Generalized Convexity

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The definitions of generalized pseudoconvex,generalized quasiconvex and its strictly generalized convexity were presented for the static programming at locally star-shaped set using the concept of right-upper derivative and the concept of sublinear. The sufficient and necessary conditions of the static programming were derived in terms of a generalized Lemma in this paper. The results obtained are useful for the further study on the duality of static programming and cover many already known conditions.

  6. Model Checking Is Static Analysis of Modal Logic

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis

    2010-01-01

    it can give an exact characterisation of the semantics of formulae in a modal logic. This shows that model checking can be performed by means of state-of-the-art approaches to static analysis and allow us to conclude that the problems of model checking and static analysis are reducible to each other....... In terms of computational complexity we show that model checking by means of static analysis gives the same complexity bounds as are known for traditional approaches to model checking....

  7. Chiral transformation: From single nanowire to double helix

    KAUST Repository

    Wang, Yong

    2011-12-21

    We report a new type of water-soluble ultrathin Au-Ag alloy nanowire (NW), which exhibits unprecedented behavior in a colloidal solution. Upon growth of a thin metal (Pd, Pt, or Au) layer, the NW winds around itself to give a metallic double helix. We propose that the winding originates from the chirality within the as-synthesized Au-Ag NWs, which were induced to untwist upon metal deposition. © 2011 American Chemical Society.

  8. Quantum singularities in spherically symmetric, conformally static spacetimes

    CERN Document Server

    Helliwell, T M

    2013-01-01

    A definition of quantum singularity for the case of static spacetimes has recently been extended to conformally static spacetimes. Here the theory behind quantum singularities in conformally static spacetimes is reviewed, and then applied to a class of spherically symmetric, conformally static spacetimes, including as special cases those studied by Roberts, by Fonarev, and by Husain, Martinez, and N\\'u\\~nez. We use solutions of the generally coupled, massless Klein-Gordon equation as test fields. In this way we find the ranges of metric parameters and coupling coefficients for which classical timelike singularities in these spacetimes are healed quantum mechanically.

  9. From Flow Logic to Static Type Systems in Coordination Languages

    DEFF Research Database (Denmark)

    De Nicola, Rocco; Gorla, Daniele; Hansen, René Rydhof;

    2008-01-01

    Coordination languages are often used to describe open ended systems. This makes it challenging to develop tools for guaranteeing security of the coordinated systems and correctness of their interaction. Successful approaches to this problem have been based on type systems with dynamic checks......; therefore, the correctness properties cannot be statically enforced. By contrast, static analysis approaches based on Flow Logic usually guarantee properties statically. In this paper we show how to combine these two approaches to obtain a static type system for describing secure access to tuple spaces and...... safe process migration for a dialect of the language Klaim....

  10. Brane-world generalizations of the Einstein static universe

    International Nuclear Information System (INIS)

    A static Friedmann brane in a five-dimensional bulk (Randall-Sundrum-type scenario) can have a very different relation between the density, pressure, curvature and cosmological constant than in the case of the general relativistic Einstein static universe. In particular, static Friedmann branes with zero cosmological constant and 3-curvature, but satisfying ρ > 0 and ρ + 3p > 0, are possible. Furthermore, we find static Friedmann branes in a bulk that satisfies the Einstein equations but is not Schwarzschild-anti-de Sitter or its specializations. In the models with negative bulk cosmological constant, a positive brane tension leads to negative density and 3-curvature

  11. Thermomechanical treatment of low-alloy copper alloys of the kind CuCo2Be and CuCo1NiBe

    Directory of Open Access Journals (Sweden)

    W. Ozgowicz

    2011-06-01

    Full Text Available Purpose: The aim of the investigations is to test the influence of the complex thermomechanical treatment on the structure and mechanical properties of low-alloy copper alloys with cobalt, beryllium and nickel of the kind CuCo2Be (CB4 and CuCo1NiBe (CCNB.Design/methodology/approach: The range of investigations comprises an analysis of the complex technique of thermomechanical treatment of the investigated alloys and the conventional thermal treatment of these alloys, the analysis of their chemical composition, a static tensile test, measurement of their hardness, observations of their structure on a light microscope and a fractographic analysis on an electron scanning microscope.Findings: The analysis of the results of investigations concerning the mechanical effect properties permitted to determine the effect of the combined thermomechanical treatment and the comparatively performed precipitation hardening on the structure and mechanical properties of the investigated low-alloy kinds of copper. The character of cracking in the course of stretching were determined basing on fractographic tests.Practical implications: The investigated copper alloys subjected to a complex thermomechanical treatment display a higher strength and lower plastic properties in comparison with these properties achieved by means of the conventional heat treatment.Originality/value: Complex thermomechanical treatment ensures an optimal strength of the investigated alloys as well as satisfying plastic properties.

  12. Static black holes and strictly static spacetimes in Einstein-Gauss-Bonnet gravity with gauge field

    OpenAIRE

    Rogatko, Marek

    2014-01-01

    We examine strictly static asymptotically flat spacetimes in Einstein-Gauss-Bonnet gravity with U(1) gauge field, revealing that, up to small curvature corrections, confomally flat slices of the spacetime in question are of Minkowski origin. We consider uncharged and charged black hole solutions in the theory, showing that, up to the small curvature limit, they are diffeomorphic to Schwarzschild_Tangherlini or Reissner-Nordstrom solutions, respectively.

  13. Latent Constructs of the Static-99R and Static-2002R: A Three-Factor Solution.

    Science.gov (United States)

    Brouillette-Alarie, Sébastien; Babchishin, Kelly M; Hanson, R Karl; Helmus, Leslie-Maaike

    2016-02-01

    The most commonly used risk assessment tools for predicting sexual violence focus almost exclusively on static, historical factors (e.g., characteristics of prior offences). Consequently, they are assumed to be unable to directly inform the selection of treatment targets or evaluate change. In this article, we argue that this limitation can be mitigated by using latent variable models as a framework to link historical risk factors to the psychological characteristics of offenders. Accordingly, we conducted a factor analysis of the 13 nonredundant items from the two most commonly used risk tools for sexual offenders (Static-99R and Static-2002R) to identify the psychological information contained in these tools. Three factors were identified: (a) persistence/paraphilia, a construct related to sexual criminality, especially of the pedophilic type; (b) youthful stranger aggression, a construct centered on young age and offence seriousness; and (c) general criminality, a construct that reflected the diversity and magnitude of criminal careers. These constructs predicted sexual recidivism with similar accuracy, but only youthful stranger aggression and general criminality predicted nonsexual recidivism. These results indicate that risk tools for sexual violence are multidimensional, and support a shift from a focus on atheoretical risk markers to the assessment of psychologically meaningful constructs. PMID:25612625

  14. Effect of Luting Cement Space on the Strain Response of Gold Crowns Under Static Compressive Loading.

    Science.gov (United States)

    Asbia, S; Ibbetson, R; Reuben, B

    2015-03-01

    The aim the work was to investigate the effect of varying degrees of luting cement thickness on the strain of the cemented gold alloy crowns under compression. Five dies with their corresponding crowns were fabricated using a lost wax technique. Three gold crowns for each die were fabricated under the control of specific die spacer layers to provide a space of 40 µm (10 layers of die-spacer thickness) and 80 µm (20 layers of die-spacer thickness). The crowns were subsequently cemented using zinc phosphate cement. The crowns were subjected to gradual static compressive loading between 10N to 250N (Newton) and the strain measured simultaneously. The results were statistically analysed using Independent t-test for the different die-spacer thickness at the 95% confidence interval (p = 0.05). It was found that a significant relationship in the three thicknesses. It was concluded that the absence of die-spacer significantly reduced strain response, whereas a very little change in the strain recorded as the die spacer layers has increased. Clinically, decreasing the number of die-spacer layers is advantageous as it provides a lower strain response under static compressive loading that would improve the longevity of the cemented full crowns inside the patient's mouth. PMID:26415332

  15. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  16. Refractory alloy component fabrication

    International Nuclear Information System (INIS)

    Purpose of this report is to describe joining procedures, primarily welding techniques, which were developed to construct reliable refractory alloy components and systems for advanced space power systems. Two systems, the Nb-1Zr Brayton Cycle Heat Receiver and the T-111 Alloy Potassium Boiler Development Program, are used to illustrate typical systems and components. Particular emphasis is given to specific problems which were eliminated during the development efforts. Finally, some thoughts on application of more recent joining technology are presented. 78 figures

  17. Pareto-optimal alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Johannesson, Gisli Holmar; Ruban, Andrei; Skriver, Hans Lomholt; Jacobsen, Karsten Wedel; Nørskov, Jens Kehlet

    2003-01-01

    cost. In this letter we present a database consisting of the lattice parameters, bulk moduli, and heats of formation for over 64 000 ordered metallic alloys, which has been established by direct first-principles density-functional-theory calculations. Furthermore, we use a concept from economic theory......, the Pareto-optimal set, to determine optimal alloy solutions for the compromise between low compressibility, high stability, and cost....

  18. Dynamic Compression Properties of an Ultrafine-Grained Al-26 wt.% Si Alloy Fabricated by Equal-Channel Angular Pressing

    Science.gov (United States)

    Jiang, Jinghua; Shi, Jun; Yao, YiHong; Ma, Aibin; Song, Dan; Yang, Donghui; Chen, Jianqing; Lu, Fumin

    2015-05-01

    The grains of a hypereutectic Al-26 wt.% Si alloy were drastically refined by multi-pass equal-channel angular pressing (ECAP). Compression deformation characteristics of the alloy with different microstructure were examined at two dynamic strain rates (700, 1000 s-1) by a split-Hopkinson pressure bar system and at a quasi-static strain rate (0.001 s-1) by a universal testing machine, respectively. The results reveal that the Al-26 wt.% Si alloy is strain-rate sensitive under those compression conditions, i.e., the initial yield stress and the flow stress considerably increase with the strain rate. Grain refinement through ECAP improves the strain-rate sensitivity of the alloy. With rising the ECAP temperature, the yield stress of the ultrafine-grained alloy decreases but the strain value increases during dynamic compression.

  19. Intense cavitation at extreme static pressure.

    Science.gov (United States)

    Pishchalnikov, Yuri A; Gutierrez, Joel; Dunbar, Wylene W; Philpott, Richard W

    2016-02-01

    Cavitation is usually performed at hydrostatic pressures at or near 0.1 MPa. Higher static pressure produces more intense cavitation, but requires an apparatus that can build high amplitude acoustic waves with rarefactions exceeding the cavitation threshold. The absence of such an apparatus has prevented the achievement of intense acoustic cavitation, hindering research and the development of new applications. Here we describe a new high-pressure spherical resonator system, as well as experimental and modeling results in water and liquid metal (gallium), for cavitation at hydrostatic pressures between 10 and 150 MPa. Our computational data, using HYADES plasma hydrodynamics code, show the formation of dense plasma that, under these conditions, reaches peak pressures of about three to four orders of magnitude greater than the hydrostatic pressure in the bulk liquid and temperatures in the range of 100,000 K. Passive cavitation detection (PCD) data validate both a linear increase in shock wave amplitude and the production of highly intense concentrations of mechanical energy in the collapsing bubbles. High-speed camera observations show the formation of bubble clusters from single bubbles. The increased shock wave amplitude produced by bubble clusters, measured using PCD and fiber optic probe hydrophone, was consistent with current understanding that bubble clusters enable amplification of energy produced. PMID:26341849

  20. Static balancing behaviour of the mandible.

    Science.gov (United States)

    Hellmann, Daniel; Brüstle, Fabian; Terebesi, Sophia; Giannakopoulos, Nikolaos N; Eberhard, Lydia; Rammelsberg, Peter; Schindler, Hans J

    2015-12-01

    The objective of this study was to investigate the mechanisms of physiological control of the craniomandibular system during force-controlled biting: in intercuspation, restricted by predetermined anatomic-geometrical conditions [i.e. biting in intercuspation (BIC)]; and on a hydrostatic system [i.e. auto-balanced static equilibrium of the mandible (BAL)], in which the mandible is balanced under unrestricted occlusal conditions. For 20 healthy subjects, the spatial positions of the condyles, the lower molars, and the incisal point were measured, and the electromyographic (EMG) activity of the musculus masseter and musculus temporalis anterior were recorded bilaterally, during force-controlled biting (50, 75, 100 N) on a hydrostatic device. The results were compared with those obtained during BIC. During BAL, the neuromuscular system stabilizes one condyle, so it behaves as a virtual fulcrum, and all available biomechanical degrees of freedom of the opposite side are used to achieve a bilaterally equal vertical distance between the upper and lower dental arches. The variability of the positions of the molars was significantly smaller than for the condyles. The EMG co-contraction ratios calculated for homonymous muscle regions revealed significant differences between BIC and BAL, specifically, greater symmetry during BAL with substantial asymmetry of approximately 25% remaining. In conclusion, the results revealed precise neuromuscular control of the position of the lower dental arch; this information might form the basis for interference-free tracking of the mandible in intercuspation under different conditions. PMID:26446049

  1. Artificial neural networks for static security assessment

    Energy Technology Data Exchange (ETDEWEB)

    Niebur, D.; Fischl, R.

    1997-12-31

    A reliable, continuous supply of electric energy is essential for the functioning of today`s complex societies. Due to a combination of increasing energy consumption and impediments of various kinds to the extension of existing electric transmission networks, these power systems are operated closer and closer to their limits. This situation requires a significantly less conservative power system operation and control regime which, in turn, is possible only by monitoring the system state in much more detail than was necessary previously. Fortunately, the large quantity of information required can be provided in many cases through recent advances in telecommunications and computing techniques. There is, however, a lack of evaluation techniques required to extract the salient information and to use it for higher-order processing. Whilst the sheer quantity of available information is always a problem, this situation is aggravated in emergency situations when rapid decisions are required. Furthermore, the behaviour of power systems is highly non-linear. Monitoring and control involves several hundred variables which are only partly available by measurements. Load demands and dynamic loads are difficult to model. Therefore models appropriate for normal situations might become invalid in emergency situations. These problems provide important motivation to explore novel data processing and programming techniques from the vast pool of artificial intelligence techniques. The following section gives a short introduction to static security assessment. (Author)

  2. A multinuclear static NMR study of geopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Favier, Aurélie, E-mail: aurelie.favier@epfl.ch [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); Habert, Guillaume [Institute for Construction and Infrastructure Management, ETH Zurich, CH-8093 Zurich (Switzerland); Roussel, Nicolas [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); D' Espinose de Lacaillerie, Jean-Baptiste [Ecole Supérieure de Physique et de Chimie Indusrtrielles de la Ville de Paris (ESPCI), ParisTech, PSL Research University, Soft Matter Sciences and Engineering Laboratory SIMM, CNRS UMR 7615, 10 rue Vauquelin, F-75005 Paris (France)

    2015-09-15

    Geopolymers are inorganic binders obtained by alkali activation of aluminosilicates. While the structure of geopolymers is now well understood, the details of the geopolymerisation reaction and their impact on the rheology of the paste remain uncertain. In this work, we follow the elastic properties of a paste made with metakaolin and sodium silicate solution. After the first sharp increase of elastic modulus occurring a few hundred of seconds after mixing and related to the heterogeneous formation of an alumina–silicate gel with a molar ratio Si/Al < 4 located at the grains boundaries, we focus on the progressive increase in elastic modulus on a period of few hours during the setting of the geopolymer. In this study, we combine the study of rheological properties of the paste with {sup 23}Na, {sup 27}Al and {sup 29}Si static NMR measurement in order to better understand the origin of this second increase in elastic modulus. Our results show that, after a few hours, Al and Na evolution in the liquid phase are concomitant. This suggests the precipitation of an aluminosilicate phase where Al is in tetrahedral position and Na compensates the charge. Furthermore, Si speciation confirms this result and allows us to identify the precipitation of a product, which has a chemical composition close to the final composition of geopolymer. This study provides strong evidence for a heterogeneous formation of an aluminosilicate glass directly from the first gel and the silicate solution without the need for a reorganisation of Gel 1 into Gel 2.

  3. Constituent gluons and the static quark potential

    Science.gov (United States)

    Greensite, Jeff; Szczepaniak, Adam P.

    2016-04-01

    We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a truncated-basis treatment of hadronic states which include constituent gluons. As an illustration, we apply this hybrid approach to the heavy quark potential, for quark-antiquark separations up to 2.4 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of 4 times greater than the asymptotic string tension. In our approach we show that a single constituent gluon is in principle sufficient, up to 2.4 fm, to reduce this overshoot by the factor required. The static potential remains linear, although the precise value of the string tension depends on details of the Couloumb gauge ghost and gluon propagators in the infrared regime. In this connection we present new lattice results for the transverse gluon propagator in position space.

  4. Review of Static Compensation of Autonomous Systems

    Directory of Open Access Journals (Sweden)

    Ambarnath Banerji

    2012-01-01

    Full Text Available Abstract Deregulation of the electric power energy market has thrown open opportunities for tapping the large number of small pockets of renewable energy sources with the asynchronous generators. Whether the power is supplied by asynchronous generator or by the grid at the remote location, its quality has become an important aspect for consumers of electricity. Efforts have been made to improve the power quality using passive filters, active filters and the new concept of Custom Power. Use of Custom power devices ensures that a load do not pollute the power supply of the other loads. One such custom power device is the DSTATCOM (Distribution Static Compensator which is connected in shunt at the load end. The heart of the DSTATCOM is an inverter. The focus on the autonomous generation has increased in the recent years. The paper presents a comprehensive review of the DSTATCOM used for autonomous generation. It is aimed at providing a broad perspective on the status of DSTATCOM, used with Asynchronous generators, vis-à-vis its working principle, topology, solid state switching devices and technology, supply system, control methodologies and approaches, technical and economic considerations, etc. to researchers and application engineers dealing with power quality aspects of Autonomous Systems. Classified manner in which the references are presented in this paper will serve them as quick and useful reference.

  5. The influence of music on static posturography.

    Science.gov (United States)

    Forti, Stella; Filipponi, Eliana; Di Berardino, Federica; Barozzi, Stefania; Cesarani, Antonio

    2010-01-01

    It is well known that high intensity sounds modify balance by activating the saccule, which is sensitive to both vestibular and acoustic stimuli. Few studies have examined the effects of music on the postural responses in healthy subjects. The aim of this study was to evaluate the influence of different types of music (Mozart, Köhler, Köhler with a carrier of 12 KHz and subjects' favourite music) on twelve healthy subjects standing on a stabilometric platform. With each type of music, all subjects underwent static posturography with eyes opened and eyes closed, and with and without foam pads. We evaluated the length and the surface of body sway and the correlation between them, and we analyzed the visual, vestibular and somatosensory sub-components. Listening to different types of music did not significantly change the stabilometric variables, with the exception of listening to Mozart's Jupiter, which caused a significant reduction in the visual component with a consequent increase in both the vestibular and somatosensory inputs. Further studies are needed to determine the effect of Mozart's music in modifying the sensory strategy in the rehabilitation of patients with vestibular impairments. PMID:20826933

  6. A multinuclear static NMR study of geopolymerisation

    International Nuclear Information System (INIS)

    Geopolymers are inorganic binders obtained by alkali activation of aluminosilicates. While the structure of geopolymers is now well understood, the details of the geopolymerisation reaction and their impact on the rheology of the paste remain uncertain. In this work, we follow the elastic properties of a paste made with metakaolin and sodium silicate solution. After the first sharp increase of elastic modulus occurring a few hundred of seconds after mixing and related to the heterogeneous formation of an alumina–silicate gel with a molar ratio Si/Al < 4 located at the grains boundaries, we focus on the progressive increase in elastic modulus on a period of few hours during the setting of the geopolymer. In this study, we combine the study of rheological properties of the paste with 23Na, 27Al and 29Si static NMR measurement in order to better understand the origin of this second increase in elastic modulus. Our results show that, after a few hours, Al and Na evolution in the liquid phase are concomitant. This suggests the precipitation of an aluminosilicate phase where Al is in tetrahedral position and Na compensates the charge. Furthermore, Si speciation confirms this result and allows us to identify the precipitation of a product, which has a chemical composition close to the final composition of geopolymer. This study provides strong evidence for a heterogeneous formation of an aluminosilicate glass directly from the first gel and the silicate solution without the need for a reorganisation of Gel 1 into Gel 2

  7. 38 CFR 4.57 - Static foot deformities.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Static foot deformities... FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.57 Static foot deformities... anatomical changes, as compared to normal, in the relationship of the foot and leg, particularly to...

  8. All Charged Up!--Experimenting with Static Electricity

    Science.gov (United States)

    Roman, Harry T.

    2011-01-01

    Build-up of static electricity happens readily when the air is cold and dry and is a common part of life. There are lots of ways to make students aware of static electricity--and many things one can teach them about its applications in today's industry. In this article, the author describes examples and experiments that will bring static…

  9. 14 CFR 29.610 - Lightning and static electricity protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...

  10. The Instabilities of Bianchi Type IX Einstein Static Universes

    CERN Document Server

    Barrow, John D

    2011-01-01

    We investigate the stability of the Einstein static universe as a non-LRS Bianchi type IX solution of the Einstein equations in the presence of both non-tilted and tilted fluids. We find that the static universe is unstable to homogeneous perturbations of Bianchi type IX to the future and the past.

  11. Hanging an Airplane: A Case Study in Static Equilibrium

    Science.gov (United States)

    Katz, Debora M.

    2009-01-01

    Our classrooms are filled with engineering majors who take a semester-long course in static equilibrium. Many students find this class too challenging and drop their engineering major. In our introductory physics class, we often breeze through static equilibrium; to physicists equilibrium is just a special case of Newton's second law. While it is…

  12. Static and Transient Cavitation Threshold Measurements for Mercury

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, F.; Taleyarkhan, R.P.

    1999-11-14

    Transient and static cavitation thresholds for mercury as a function of the cover gas (helium or air), and pressure are reported. Both static and transient cavitation onset pressure thresholds increase linearly with cover gas pressure. Additionally, the cavitation thresholds as a function of dissolved gases were also measured and are reported.

  13. 14 CFR 25.177 - Static lateral-directional stability.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static lateral-directional stability. 25.177 Section 25.177 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Stability § 25.177 Static...

  14. Slipping and Tipping: Measuring Static Friction with a Straightedge

    Science.gov (United States)

    Dietz, Eric; Aguilar, Isaac

    2012-01-01

    Following a discussion of forces, torques, and the conditions for static equilibrium, I tell my introductory mechanics class that I will show them how to measure the coefficient of static friction, us, between the surfaces of a block and the front bench using "nothing but a straightedge". After a few seconds of hushed anticipation, I nudge the…

  15. Texture in low-alloyed uranium alloys

    International Nuclear Information System (INIS)

    The dependence of the preferred orientation of cast and heat-treated polycrystalline adjusted uranium and uranium -0.1 w/o chromium alloys on the production process was studied. The importance of obtaining material free of preferred orientation is explained, and a survey of the regular methods to determine preferred orientation is given. Dilatometry, tensile testing and x-ray diffraction were used to determine the extent of the directionality of these alloys. Data processing showed that these methods are insufficient in a case of a material without any plastic forming, because of unreproducibility of results. Two parameters are defined from the results of Schlz's method diffraction test. These parameters are shown theoretically and experimentally (by extreme-case samples) to give the deviation from isotropy. Application of these parameters to the examined samples showes that cast material has preferred orientation, though it is not systematic. This preferred orientation was reduced by adequate heat treatments

  16. Static hybrid potential in D dimensions at short distances

    International Nuclear Information System (INIS)

    We compute the energy of a static hybrid, i.e., of a hybrid quarkonium with static quark and antiquark, at short distances in D=4,3, dimensions. The soft contribution to this energy is the static potential of a color-octet quark-antiquark pair at short distances, which is known at two loops for arbitrary D. We have checked this expression employing thermal field theory methods. Using the effective field theory potential nonrelativistic QCD we calculate the ultrasoft contributions to the hybrid (and singlet) static energy at the two-loop level. We then present new results for the static hybrid energy/potential and the hybrid decay width in three and four dimensions. Finally we comment on the meaning of the perturbative results in two space-time dimensions, where the hybrid does not exist.

  17. Contagion processes on the static and activity driven coupling networks

    CERN Document Server

    Lei, Yanjun; Guo, Quantong; Ma, Yifang; Li, Meng; Zheng, Zhiming

    2015-01-01

    The evolution of network structure and the spreading of epidemic are common coexistent dynamical processes. In most cases, network structure is treated either static or time-varying, supposing the whole network is observed in a same time window. In this paper, we consider the epidemic spreading on a network consisting of both static and time-varying structures. At meanwhile, the time-varying part and the epidemic spreading are supposed to be of the same time scale. We introduce a static and activity driven coupling (SADC) network model to characterize the coupling between static (strong) structure and dynamic (weak) structure. Epidemic thresholds of SIS and SIR model are studied on SADC both analytically and numerically with various coupling strategies, where the strong structure is of homogeneous or heterogeneous degree distribution. Theoretical thresholds obtained from SADC model can both recover and generalize the classical results in static and time-varying networks. It is demonstrated that weak structure...

  18. WC-3015 alloy (high-temperature alloy)

    International Nuclear Information System (INIS)

    WC-3015 Nb alloy containing 28 to 30 Hf, 1 to 2 Zr, 13 to 16 W, 0 to 4 Ta, 0 to 5 Ti, 0.07 to 0.33 C, less than or equal to 0.02 N, less than or equal to 0.03 O, less than or equal to 0.001 H was developed for use at high temperature in oxidizing environments. Its composition can be tailored to meet specific requirements. When WC-3015 is exposed to O at elevated temperature, Hf and Nb oxidized preferentially and HfO2 dissolves in Nb2O5 to form 6HfO-Nb2O5. This complex oxide has a tight cubic lattice which resists the diffusion of O into the substrate. During 24-h exposure to air at 24000F, the alloy oxidizes to a depth of approximately 0.035 in. with a surface recession of 0 to 0.004 in. Oxidation resistance of WC-3015 welds and base material can be further enhanced greatly by applying silicide coatings. WC-3015 alloy can be machined by conventional and electrical-discharge methods. It can be hot worked readily by extrusion, forging or rolling. Cold working can be used at room or elevated temperature. It can be welded by the electron-beam or Tig processes. Physical constants, typical mechanical properties at 75 to 24000F, and effects of composition and heat treatment on tensile and stress-rupture properties of the alloy are tabulated

  19. Solute segregation kinetics and dislocation depinning in a binary alloy

    Science.gov (United States)

    Dontsova, E.; Rottler, J.; Sinclair, C. W.

    2015-06-01

    Static strain aging, a phenomenon caused by diffusion of solute atoms to dislocations, is an important contributor to the strength of substitutional alloys. Accurate modeling of this complex process requires both atomic spatial resolution and diffusional time scales, which is very challenging to achieve with commonly used atomistic computational methods. In this paper, we use the recently developed "diffusive molecular dynamics" (DMD) method that is capable of describing the kinetics of the solute segregation process at the atomic level while operating on diffusive time scales in a computationally efficient way. We study static strain aging in the Al-Mg system and calculate the depinning shear stress between edge and screw dislocations and their solute atmospheres formed for various waiting times with different solute content and for a range of temperatures. A simple phenomenological model is also proposed that describes the observed behavior of the critical shear stress as a function of segregation level.

  20. Titanium alloys. Advances in alloys, processes, products and applications

    OpenAIRE

    Blenkinsop, P.

    1993-01-01

    The last few years have been a period of consolidation of existing alloys and processes. While the aerospace industry remains the principal driving force for alloy development, the paper illustrates examples of new markets being established in "older" alloys, by a combination of product/process development and a re-examination of engineering design parameters. Considerable attention is still being directed towards the titanium aluminide systems, but other more conventional alloy developments ...

  1. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan; Schiøtz, Jakob

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  2. Resistance to deformation of steels and alloys in continuous hot rolling

    International Nuclear Information System (INIS)

    A method is suggested for calculating the variation of the metal and alloy resistance to deformation in hot rolling in a continuous mill; the method is based on the relationship between high-temperature deformation strengthening and static weakening. The kinetics of the static weakening are described by a system of equations containing parameters that are determined by means of a standard plastometric experiment with a single-step loading. The calculated level of remaining stresses makes it possible to determine the shift in the yield limit of the strengthened material as compared with that of its unstrengthened state

  3. The effect of microstructure of low-alloy spheroidal cast iron on impact strength

    Directory of Open Access Journals (Sweden)

    T. Szykowny

    2010-01-01

    Full Text Available The study presents an evaluation of the effect of microstructure of low-alloy spheroidal cast iron on impact strength within the temperature range from –60 to 100°C. Analyses were conducted on one type of cast iron containing 0.51% Cu and 0.72% Ni. Cast iron was austempered or normalized. Values of KCV and static mechanical properties were determined. Structural and fractographic analyses were based on light and scanning microscopy as well as X-ray diffraction. It was found that thermal processing considerably improves impact strength in relation to cast iron after casting. At the same time static mechanical properties are enhanced.

  4. Static mechanical properties of buffer material

    International Nuclear Information System (INIS)

    The buffer material is expected to maintain its low water permeability, self-sealing properties, radionuclides adsorption and retardation properties, thermal conductivity, chemical buffering properties, overpack supporting properties, stress buffering properties, etc. over a long period of time. Natural clay is mentioned as a material that can relatively satisfy above. Among the kinds of natural clay, bentonite when compacted is superior because (i) it has exceptionally low water permeability and properties to control the movement of water in buffer, (ii) it fills void spaces in the buffer and fractures in the host rock as it swells upon water uptake, (iii) it has the ability to exchange cations and to adsorb cationic radioelements. In order to confirm these functions for the purpose of safety assessment, it is necessary to evaluate buffer properties through laboratory tests and engineering-scale tests, and to make assessments based on the ranges in the data obtained. This report describes the procedures, test conditions, results and examinations on the buffer material of unconfined compression tests, one-dimensional consolidation tests, consolidated-undrained triaxial compression tests and consolidated-undrained triaxial creep tests that aim at getting hold of static mechanical properties. We can get hold of the relationship between the dry density and tensile stress etc. by Brazilian tests, between the dry density and unconfined compressive strength etc. by unconfined compression tests, between the consolidation stress and void ratio etc. by one-dimensional consolidation tests, the stress pass of each effective confining pressure etc. by consolidated-undrained triaxial compression tests and the axial strain rate with time of each axial stress etc. by consolidated-undrained triaxial creep tests. (author)

  5. Structure and Thermal Parameters of Ni20Pd80 Alloy

    Institute of Scientific and Technical Information of China (English)

    S. Ahmad; A.B. Ziya; A. Aziz1; Z.I. Zafar

    2009-01-01

    The structure and thermal parameters of Ni20Pd80 alloy were studied by X-ray diffraction(XRD). The diffraction experiments performed in the temperature range of 308-1100 K revealed that the alloy formed a face centered cubic (fcc) Al-type structure. The temperature dependence of the lattice parameters was investigated by using the Bragg line displacement method showing that the lattice parameter increases with the increase of temperature. The mean linear thermal expansion (MLTE(%)), coefficient of thermal expansion (CTE, α), the characteristic Debye temperature (θD) and mean square amplitudes of vibration were determined from XRD data. The value of Debye temperature was found to be 253 K. It was found that temperature factor was independent of the static displacements.

  6. Grain refining effect of magnetic field on Mg2Ni0.8Mn0.2 hydrogen storage alloys during rapid quenching

    International Nuclear Information System (INIS)

    The effect of static magnetic field treatment for synthesis of Mg2Ni0.8Mn0.2 alloys during rapid quenching was investigated in this paper. X-ray diffraction (XRD) and scanning electron microscope (SEM) results show that the transversal static magnetic field can effectively refine the grain size, producing nanocrystalline inside. This distinct phenomenon is probably attributed to the Lorentz force suppressing the crystallization of the hydrogen storage alloys and the thermoelectric effect. Mainly due to the grain refinement, the discharge capacity of Mg2Ni0.8Mn0.2 alloy is raised from 79 to about 200 mA h g−1. It is confirmed that Mg2Ni0.8Mn0.2 alloy by magnetic field assisted approach possesses enhanced electrochemical kinetics and relatively high corrosion resistance against the alkaline solution, thus resulting in higher electrochemical properties

  7. Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Schille, Ch., E-mail: Christine.Schille@med.uni-tuebingen.de [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Braun, M.; Wendel, H.P. [University Hospital Tuebingen, Div. Congenital and Paediatric Cardiac Surgery, University Children' s Hospital, Tuebingen, Germany, Calwerstr. 7/1, D-72076 Tuebingen (Germany); Scheideler, L. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Hort, N. [GKSS Research Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Reichel, H.-P. [Weissensee Company, Buergermeister-Ebert-Str. 30-32, D-36124 Eichenzell (Germany); Schweizer, E.; Geis-Gerstorfer, J. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Corrosion of eight Mg-based Biomaterials was tested in saline and human blood. Black-Right-Pointing-Pointer Corrosion behaviour in physiological saline and in blood was entirely different. Black-Right-Pointing-Pointer Al and Zn had the highest influence on corrosion behaviour in both electrolytes. Black-Right-Pointing-Pointer MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. Black-Right-Pointing-Pointer Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBS{sup minus} (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBS{sup minus} and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight

  8. Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

    International Nuclear Information System (INIS)

    Highlights: ► Corrosion of eight Mg–based Biomaterials was tested in saline and human blood. ► Corrosion behaviour in physiological saline and in blood was entirely different. ► Al and Zn had the highest influence on corrosion behaviour in both electrolytes. ► MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. ► Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBSminus (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBSminus and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight loss was observed. When alloys are ranked according to corrosion susceptibility, the results differ also between the test systems. The Mg

  9. Including heavy spin effects in a lattice QCD study of static-static-light-light tetraquarks

    CERN Document Server

    Bicudo, Pedro; Wagner, Marc

    2016-01-01

    In previous works we predicted the existence of a $\\bar b \\bar b u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ using the static approximation for the $\\bar b$ quarks and neglecting heavy spin effects. Since the binding energy is of the same order as expected for these heavy spin effects, it is essential to include them in the computation. Here we present a corresponding method and show evidence that binding is only slightly weakened and that the $\\bar b \\bar b u d$ tetraquark persists.

  10. Recrystallization texture and microstructure of an ODS Fe40Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Suzon, E.; Wagner, F.; Grosdidier, T. [Lab. d' Etudes des Textures et Applications aux Materiaux (LETAM) - UMR CNRS, Univ. de Metz, Ile du Saulcy, Metz (France)

    2003-07-01

    The general purpose of our work is to study the mechanisms responsible for texture and microstructure evolutions during static recrystallization in a fine-grained ODS Fe-40Al alloy initially processed by extrusion of mechanically alloyed powders. The present contribution will show that despite very similar textures of the as-deformed samples, the recrystallization textures were found to be very different for 10 and 16% compression strain. A microstructure investigation also revealed that these differences in crystallographic textures were concomitant with a strong change in the morphology of the recrystallized grains. (orig.)

  11. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    Directory of Open Access Journals (Sweden)

    Berat Barıs BULDUM

    2013-01-01

    Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

  12. Development of new Co–Cr–W-based biomedical alloys: Effects of microalloying and thermomechanical processing on microstructures and mechanical properties

    International Nuclear Information System (INIS)

    Highlights: • A strategy to design Co–Cr–W–Si–C alloys for dental restorations is proposed. • This approach combines microalloying with thermomechanical processing. • Hot-rolled alloys exhibited refined grains and high lattice defect densities. • Static recrystallization during cooling also modifies the mechanical properties. • The designed alloys excel in terms of both fabrication and mechanical properties. - Abstract: The application of computer-aided design and computer-aided manufacturing (CAD/CAM) to dentistry has recently attracted considerable attention as a new technique for designing and fabricating custom-made dental implants. Here, a strategy combining microalloying with thermomechanical processing are described to design new Co–28Cr–9W–1Si–C (wt%) alloys for use as disks in the CAD/CAM-based machining of dental restorations. On the basis of our thermodynamic calculations, Si and C were selected as alloying elements that cause the brittle σ phase precipitates to be replaced with the plastically deformable Laves phase and thus enhance the alloy’s hot workability. The effect of thermomechanical processing on the microstructure evolution and mechanical properties of the designed alloys was preliminarily studied by performing multipass hot rolling. The hot-rolled alloys exhibited refined grains (mean grain sizes ∼10 μm) and high densities of lattice defects (dislocations, stacking faults, etc.), both of which were obtained as a result of dynamic recrystallization during hot rolling. It was found experimentally that this approach permits the alloy strength and ductility to be increased simultaneously. The static recrystallization occurring during cooling after deformation also modifies the mechanical properties of the alloys. Carbon doping (<0.1 wt%) increases the amount of precipitates and further improves both the strength and elongation-to-failure of the hot-rolled alloys. Thus, the newly developed alloys have advantageous

  13. Oxidation characteristics of Ti-14Al-21Nb ingot alloy

    Science.gov (United States)

    Sankaran, Sankara N.; Clark, Ronald K.; Unnam, Jalaiah; Wiedemann, Karl E.

    1990-01-01

    Static oxidation kinetics of Ti14Al21Nb (wt pct) ingot alloy were studied in air over the temperature interval of 649 to 1093 C in a thermogravimetric apparatus. The oxidation products were characterized by x ray diffraction, electron microprobe analysis, energy dispersive x ray analysis, and Auger electron spectroscopy. Cross-sections of the oxidized samples were also examined using light and scanning electron microscopy. The oxidation rate was substantially lower than the conventional alloys of titanium, but the kinetics displayed a complex behavior involving two or more oxidation rates depending on the temperature and duration of exposure. The primary oxide formed was TiO2, but this oxide was doped with Nb. Small amounts of Al2O3 and TiN were also present in the scale. Diffusion of oxygen into the alloy was observed and the diffusivity seemed to be dependent on the microstructure of the metal. A model was presented to explain the oxidation behavior of the alloy in terms of the reduction in the oxygen diffusivity in the oxide caused by the modification of the defect structure of TiO2 by Nb ions.

  14. Oxidation characteristics of Ti-14Al-21Nb ingot alloy

    International Nuclear Information System (INIS)

    Static oxidation kinetics of Ti14Al21Nb (wt pct) ingot alloy were studied in air over the temperature interval of 649 to 1093 C in a thermogravimetric apparatus. The oxidation products were characterized by x ray diffraction, electron microprobe analysis, energy dispersive x ray analysis, and Auger electron spectroscopy. Cross-sections of the oxidized samples were also examined using light and scanning electron microscopy. The oxidation rate was substantially lower than the conventional alloys of titanium, but the kinetics displayed a complex behavior involving two or more oxidation rates depending on the temperature and duration of exposure. The primary oxide formed was TiO2, but this oxide was doped with Nb. Small amounts of Al2O3 and TiN were also present in the scale. Diffusion of oxygen into the alloy was observed and the diffusivity seemed to be dependent on the microstructure of the metal. A model was presented to explain the oxidation behavior of the alloy in terms of the reduction in the oxygen diffusivity in the oxide caused by the modification of the defect structure of TiO2 by Nb ions

  15. Electron Beam Freeform Fabrication of Titanium Alloy Gradient Structures

    Science.gov (United States)

    Brice, Craig A.; Newman, John A.; Bird, Richard Keith; Shenoy, Ravi N.; Baughman, James M.; Gupta, Vipul K.

    2014-01-01

    Historically, the structural optimization of aerospace components has been done through geometric methods. A monolithic material is chosen based on the best compromise between the competing design limiting criteria. Then the structure is geometrically optimized to give the best overall performance using the single material chosen. Functionally graded materials offer the potential to further improve structural efficiency by allowing the material composition and/or microstructural features to spatially vary within a single structure. Thus, local properties could be tailored to the local design limiting criteria. Additive manufacturing techniques enable the fabrication of such graded materials and structures. This paper presents the results of a graded material study using two titanium alloys processed using electron beam freeform fabrication, an additive manufacturing process. The results show that the two alloys uniformly mix at various ratios and the resultant static tensile properties of the mixed alloys behave according to rule-of-mixtures. Additionally, the crack growth behavior across an abrupt change from one alloy to the other shows no discontinuity and the crack smoothly transitions from one crack growth regime into another.

  16. Structural thermodynamics of alloys

    CERN Document Server

    Manenc, Jack

    1973-01-01

    Technical progress has for a very long time been directly dependent on progress in metallurgy, which is itself connected with improvements in the technology of alloys. Metals are most frequently used in the form of alloys for several reasons: the quantity of pure metal in its native state in the earth's crust is very limited; pure metals must be extracted from ores which are themselves impure. Finally, the methods of treatment used lead more easily to alloys than to pure metals. The most typical case is that of iron, where a pure ore may be found, but which is the starting point for cast iron or steel, alloys of iron and carbon. In addition, the properties of alloys are in general superior to those of pure metals and modem metallurgy consists of controlling these properties so as to make them conform to the requirements of the design office. Whilst the engineer was formerly compelled to adapt his designs and constructions to the materials available, such as wood, stone, bronze, iron, cast iron and ordinary st...

  17. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    OpenAIRE

    Berat Barıs BULDUM; Aydın SIK; Iskender OZKUL

    2013-01-01

    Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attra...

  18. Productive Machining of Titanium Alloys

    OpenAIRE

    Čejka, Libor

    2013-01-01

    This diploma thesis is focused on a productive machining of titanium alloys. At the beginning it deals about titanium and its alloys. It describes chip generation mechanism, tool blunting and surface quality. Further it contains modern strategies of efficient titanium alloys machining. Then it analyzes contemporary manufacturing technology of hinge made of titanium alloy Ti-6Al-4V in Frentech Aerospace s.r.o. company, and at the end finds possibility of savings by inovation of roughing process.

  19. Pre-exposure to moving form enhances static form sensitivity.

    Directory of Open Access Journals (Sweden)

    Thomas S A Wallis

    Full Text Available BACKGROUND: Motion-defined form can seem to persist briefly after motion ceases, before seeming to gradually disappear into the background. Here we investigate if this subjective persistence reflects a signal capable of improving objective measures of sensitivity to static form. METHODOLOGY/PRINCIPAL FINDINGS: We presented a sinusoidal modulation of luminance, masked by a background noise pattern. The sinusoidal luminance modulation was usually subjectively invisible when static, but visible when moving. We found that drifting then stopping the waveform resulted in a transient subjective persistence of the waveform in the static display. Observers' objective sensitivity to the position of the static waveform was also improved after viewing moving waveforms, compared to viewing static waveforms for a matched duration. This facilitation did not occur simply because movement provided more perspectives of the waveform, since performance following pre-exposure to scrambled animations did not match that following pre-exposure to smooth motion. Observers did not simply remember waveform positions at motion offset, since removing the waveform before testing reduced performance. CONCLUSIONS/SIGNIFICANCE: Motion processing therefore interacts with subsequent static visual inputs in a way that can improve performance in objective sensitivity measures. We suggest that the brief subjective persistence of motion-defined forms that can occur after motion offsets is a consequence of the decay of a static form signal that has been transiently enhanced by motion processing.

  20. De-alloyed platinum nanoparticles

    Science.gov (United States)

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  1. Fast Algorithms to Test Robust Static Equilibrium for Legged Robots

    OpenAIRE

    Del Prete, Andrea; Tonneau, Steve; Mansard, Nicolas

    2016-01-01

    Maintaining equilibrium is of primary importance for legged systems. It is not surprising then that static equilibrium is at the core of most control/planning algorithms for legged robots. Being able to check whether a system is in static equilibrium is thus important, and doing it efficiently is crucial. While this is straightforward for a system in contact with a flat ground only, it is not the case for arbitrary contact geometries. In this paper we propose two new techniques to test static...

  2. Three-way flexible cantilever probes for static contact

    DEFF Research Database (Denmark)

    Wang, Fei; Petersen, Dirch Hjorth; Jensen, Helle Vendelbo; Hansen, Christian; Mortensen, Dennis; Friis, Lars; Hansen, Ole

    2011-01-01

    In micro four-point probe measurements, three-way flexible L-shaped cantilever probes show significant advantages over conventional straight cantilever probes. The L-shaped cantilever allows static contact to the sample surface which reduces the frictional wear of the cantilever tips. We analyze...... the geometrical design space that must be fulfilled for the cantilevers to obtain static contact with the test sample. The design space relates the spring constant tensor of the cantilevers to the minimal value of the static tip-to-sample friction coefficient. Using an approximate model, we provide...

  3. Complete classification of spherically symmetric static spacetimes via Noether symmetries

    CERN Document Server

    Ali, Farhad; Ali, Sajid

    2013-01-01

    In this paper we give a complete classification of spherically symmetric static space-times by their Noether symmetries. The determining equations for Noether symmetries are obtained by using the usual Lagrangian of a general spherically symmetric static spacetime which are integrated for each case. In particular we observe that spherically symmetric static spacetimes are categorized into six distinct classes corresponding to Noether algebra of dimensions 5, 6, 7, 9, 11 and 17. Using Noether`s theorem we also write down the first integrals for each class of such spacetimes corresponding to their Noether symmetries.

  4. Static sensitivity calculation of a novel fiber optic biosensor

    Institute of Scientific and Technical Information of China (English)

    Zhongchen Bai; Shuijie Qin; Jing Li; Dashun Huang; Xin Zhang

    2008-01-01

    A novel structure of fiber optic biosensor and its principle are introduced. The sample is detected in microchannels of several microns diameter in fiber optic biosensors. The relation between the optic fiber tapered angle and the fluorescence incident angle is calculated in signal receiving part. As the sensor is a zero-order system, calculating formula of the static sensitivity is derived. When ZnSe nano-crystalline cluster is used for marking the molecules, the static sensitivity for fiber optic biosensors is calculated. At the same time, the relation between the static sensitivity and the ratio of exciting wavelength to fluorescence wavelength is presented.

  5. The Einstein static universe in Scalar-Fluid theories

    CERN Document Server

    Boehmer, Christian G; Wright, Matthew

    2015-01-01

    A new Lagrangian framework has recently been proposed to describe interactions between relativistic perfect fluids and scalar fields. In this paper we investigate the Einstein static universe in this new class of theories, which have been named Scalar-Fluid theories. The stability of the static solutions to both homogeneous and inhomogeneous perturbations is analysed deriving the relevant cosmological perturbation equations at the linear order. We can find several configurations corresponding to an Einstein static universes which are stable against inhomogeneous perturbations, but unstable against homogeneous perturbations. This shows the possible applications of Scalar-Fluid theories to the inflationary emergent universe scenario.

  6. Hydrogen in titanium alloys

    International Nuclear Information System (INIS)

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 5000C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 1500C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement

  7. Welding of refractory alloys

    International Nuclear Information System (INIS)

    This review primarily summarizes welding evaluations supported by NASA-Lewis Research Center in the 1960s. A literature search run in preparation for this review indicates that more recent work is modest by comparison. Hence, this review restates these accomplishments briefly and addresses opportunities which have evolved in welding technology (such as lasers) in the intervening decade. Emphasis in this review is given to tantalum- and niobium-base alloys. Considerable work was also done to assure that a consistent comparison was made with tungsten. A wide variety of candidate alloys derived primarily from developments directed at aircraft propulsion applications were available. Early efforts by NASA were directed at screening studies to select promising structural alloys for the space power application. This objective required fine tuning of welding procedures, e.g., the demonstration of stringent standards for control of welding atmosphere to assure good corrosion resistance in liquid alkali metals. 16 figures, 6 tables

  8. Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Deexith Reddy

    2016-07-01

    Full Text Available Shape memory alloys (SMAs are metals that "remember" their original shapes. SMAs are useful for such things as actuators which are materials that "change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields" The potential uses for SMAs especially as actuators have broadened the spectrum of many scientific fields. The study of the history and development of SMAs can provide an insight into a material involved in cutting-edge technology. The diverse applications for these metals have made them increasingly important and visible to the world. This paper presents the working of shape memory alloys , the phenomenon of super-elasticity and applications of these alloys.

  9. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  10. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  11. Machining of Titanium Alloys

    OpenAIRE

    Karásek, Jan

    2008-01-01

    The main goal of this work is the analysis of manufacturing costs for the component of wheel´s blower. Followed by setting up the size of specific cutting force for milling operation of the titanium alloy Ti-Al6-Mo2-Cr2-Fe-Si, the used tool was a milling cutter which is made out of sintered carbide with conical and spherical face. The final values which are at intervals of 1500 to 1800 MPa were compared with the values of the Sandvik Coromant firm kc = 1690 MPa, for titanium alloy with the st...

  12. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  13. Soldering of aluminium alloys

    International Nuclear Information System (INIS)

    A literature survey about soldering in general and aluminium alloys soldering in particular is presented. The existing methods of soldering aluminium alloys are described. These include soldering with flux, soldering after preliminary plating, vacuum brazipressure and temperature (NTP), sample age calculation based on 14C half life of 5570 and 5730 years, age correction for NTP, dendrochronological corrections and the relative radiocarbon concentration. All results are given with one standard deviation. Input data test (Chauvenet's criterion), gas purity test, standard deviation test and test of the data processor are also included in the program. (author)

  14. Corrosion and Creep of Candidate Alloys in High Temperature Helium and Steam Environments for the NGNP

    Energy Technology Data Exchange (ETDEWEB)

    Was, Gary; Jones, J. W.

    2013-06-21

    This project aims to understand the processes by which candidate materials degrade in He and supercritical water/steam environments characteristic of the current NGNP design. We will focus on understanding the roles of temperature, and carbon and oxygen potential in the 750-850 degree C range on both uniform oxidation and selective internal oxidation along grain boundaries in alloys 617 and 800H in supercritical water in the temperature range 500-600 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature rang 750-850 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature range 750-850 degree C over a range of oxygen and carbon potentials in helium. Combined, these studies wil elucidate the potential high damage rate processes in environments and alloys relevant to the NGNP.

  15. Pemilihan Bahan Alloy Untuk Konstruksi Gigitiruan

    OpenAIRE

    Medila Dahlan

    2008-01-01

    Pada kedokteran gigi bahan alloy sangat banyak digunakan dalam segala bidang. Dalam pembuatan konstruksi gigitiman biasanya digunakan alloy emas, alloy kobalt kromium, alloy nikei kromium dan alloy stainless steel sebagai komponen gigitiman kerangka logam serta pembuatan mahkota dan jembatan. Pemilihan bahan alloy dapat dilakukan berdasarkan sifat yang dimiiiki oleh masing-masing bahan alloy sehingga akan didapat hasil konstmksi gigitiruan yang memuaskan. Pada pemakaiannya didaiam mulut...

  16. Hydrogen embrittlement of vanadium alloys

    International Nuclear Information System (INIS)

    The mechanical properties of several vanadium alloys were measured with the hydrogen concentration high up to 113 mg/kg. The results showed that the alloys with low mechanical strength had better properties against hydrogen embrittlement. Oxygen in the alloy, especially that in the alloys with high strength, could enhance the hydrogen embrittlement. Mechanism analysis was given to show that the brittle fracture was mainly caused by intergranular failure. The effects of oxygen concentration and the strength of the alloy were both resulted from their contributions to the grain strength and the grain boundary strength

  17. Galvanic corrosion in odontological alloys

    International Nuclear Information System (INIS)

    Galvanic corrosion can occur when different alloys are placed in direct contact within the oral cavity or within tissues. Concern has been expressed associated with the coupling of selected restorative materials as well as implant material with various alloys used for restorative procedures. This could be critical if the crown or bridge had subgingival finish line with a metallic zone in contact with the tissue, and the implant was made in titanium alloy. The present work shows the results of galvanic coupling studies done on implants of titanium alloy connected to nickel-chromium and cobalt-chromium alloys. (Author)

  18. Effect of inertia parameters on static fission path

    International Nuclear Information System (INIS)

    Properties of static (minimum potential) fission path in the formalism of Hofmann are investigated. It is pointed out that the inertial parameters greatly affect the fission path and hence the penetrability. The difficulty of determining fission path is discussed

  19. Static-light meson masses from twisted mass lattice QCD

    International Nuclear Information System (INIS)

    We compute the static-light meson spectrum using two-flavor Wilson twisted mass lattice QCD. We have considered five different values for the light quark mass corresponding to 300 MeVPSS mesons. (orig.)

  20. Static Quark Potential from the Polyakov Sum over Surfaces

    OpenAIRE

    Jaskolski, Zbigniew; Meissner, Krzysztof A.

    1993-01-01

    Using the Polyakov string ansatz for the rectangular Wilson loop we calculate the static potential in the semiclassical approximation. Our results lead to a well defined sum over surfaces in the range $1

  1. 2D seismic residual statics derived from refraction interferometry

    Science.gov (United States)

    Zhang, Chao; Zhang, Jie

    2016-07-01

    Refraction traveltimes have long been applied for deriving long-wavelength statics solutions. These traveltimes are also applied for the derivation of residual statics, but they must be sufficiently accurate at short wavelengths. In this study, we present a seismic residual statics method that applies interferometric theory to produce four stacked virtual refraction gathers with a significantly improved signal-to-noise ratio. These gathers are composed of forward and backward virtual refraction gathers for receivers and shots. By picking the first arrivals on these four gathers followed by the application of a set of refraction equations, reliable residual statics solutions can be derived. This approach can help deal with noisy data and also avoid using traveltime picks from shot gathers. We demonstrate the approach by applying it to synthetic data as well as real data.

  2. Thévenin equivalent based static contingency assessment

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a method for static security assessment of a power system and a real time static security assessment system for assessing a power system, the power system having a plurality of generators, the plurality of generators being represented in the network by a plurality...... of voltage controlled nodes, wherein the method for static security assessment of the power system comprises receiving information of a present state of the power system, determining a Thevenin equivalent for each voltage controlled node, determining for each voltage controlled node on basis of the...... evaluating the voltage angles to determine whether the network having at least one contingency admit a steady state. Also a method of providing information on a real time static security assessment of a power system is disclosed....

  3. Spherically Symmetric Static States of Wave Dark Matter

    CERN Document Server

    Parry, Alan R

    2013-01-01

    We explore spherically symmetric solutions to the Einstein-Klein-Gordon equations, the defining equations of wave dark matter, where the scalar field is of the form f(t,r) = exp(i\\omega t)F(r) for some constant \\omega\\ in R and complex-valued function F(r). We show that the corresponding metric is static if and only if F(r) = h(r)exp(ia) for some constant a in R and real-valued function h(r). We describe the behavior of the resulting solutions, which are called spherically symmetric static states. We also describe how, in the low field limit, the parameters defining these static states are related and show that these relationships imply important properties of the static states.

  4. Interaction mechanisms and biological effects of static magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tenforde, T.S.

    1994-06-01

    Mechanisms through which static magnetic fields interact with living systems are described and illustrated by selected experimental observations. These mechanisms include electrodynamic interactions with moving, ionic charges (blood flow and nerve impulse conduction), magnetomechanical interactions (orientation and translation of molecules structures and magnetic particles), and interactions with electronic spin states in charge transfer reactions (photo-induced electron transfer in photosynthesis). A general summary is also presented of the biological effects of static magnetic fields. There is convincing experimental evidence for magnetoreception mechanisms in several classes of lower organisms, including bacteria and marine organisms. However, in more highly evolved species of animals, there is no evidence that the interactions of static magnetic fields with flux densities up to 2 Tesla (1 Tesla [T] = 10{sup 4} Gauss) produce either behavioral or physiolocical alterations. These results, based on controlled studies with laboratory animals, are consistent with the outcome of recent epidemiological surveys on human populations exposed occupationally to static magnetic fields.

  5. Effects of Static Stretching and Playing Soccer on Knee Laxity

    NARCIS (Netherlands)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W.; Freiwald, Juergen

    2015-01-01

    Objective: This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Design: Randomized controlled trial. Setting: University biomechanics laboratory. Participants: Thirty-one athletes were randomly assigned into

  6. Einstein's conversion from his static to an expanding universe

    Science.gov (United States)

    Nussbaumer, Harry

    2014-02-01

    In 1917 Einstein initiated modern cosmology by postulating, based on general relativity, a homogenous, static, spatially curved universe. To counteract gravitational contraction he introduced the cosmological constant. In 1922 Alexander Friedman showed that Albert Einstein's fundamental equations also allow dynamical worlds, and in 1927 Georges Lemaître, backed by observational evidence, concluded that our universe was expanding. Einstein impetuously rejected Friedman's as well as Lemaître's findings. However, in 1931 he retracted his former static model in favour of a dynamic solution. This investigation follows Einstein on his hesitating path from a static to the expanding universe. Contrary to an often advocated belief the primary motive for his switch was not observational evidence, but the realisation that his static model was unstable.

  7. Fast static field CIPT mapping of unpatterned MRAM film stacks

    International Nuclear Information System (INIS)

    While investigating uniformity of magnetic tunnel junction (MTJ) stacks we find experimentally and analytically that variation in the resistance area product (RA) is more important to monitor as compared to the tunnel magnetoresistance (TMR), which is less sensitive to MTJ variability. The standard Current In-Plane Tunneling (CIPT) method measures both RA and TMR, but the usefulness for uniformity mapping, e.g. for tool optimization, is limited by excessive measurement time. Thus, we develop and demonstrate a fast complementary static magnetic field method focused only on measurement of RA. We compare the static field method to the standard CIPT method and find perfect agreement between the extracted RA values and measurement repeatability while the static field method is several times faster. The static field CIPT method is demonstrated for 200 mm wafer mapping showing radial as well as asymmetrical variations related to the MTJ deposition conditions. (paper)

  8. Einstein's conversion from his static to an expanding universe

    CERN Document Server

    Nussbaumer, Harry

    2013-01-01

    In 1917 Einstein initiated modern cosmology by postulating, based on general relativity, a homogeneous, static, spatially curved universe. To counteract gravitational contraction he introduced the cosmological constant. In 1922 Alexander Friedman showed that Einstein's fundamental equation also allowed dynamical worlds, and in 1927 Geroges Lemaitre, backed by observational evidence, concluded that our universe was expanding. Einstein impetuously rejected Friedman's as well as Lemaitre's findings. However, in 1931 he retracted his former static model in favour of a dynamic solution. This investigation follows Einstein on his hesitating path from a static to the expanding universe. Contrary to an often repeated belief the primary motive for his switch was not observational evidence, but the realisation that his static model was unstable.

  9. Passive elimination of static electricity in oil industry

    Directory of Open Access Journals (Sweden)

    Gaćanović Mićo

    2014-01-01

    Full Text Available This study explains the existing and real conditions of a possible passive elimination of static electricity when loading oil and oil derivatives. We are considering the formation and survival of gas bubbles both in the volume of oil in its depth, but also at the surface of oil and oil derivatives of the partly filled reservoir, and formation of both volume and surface electric charge in oil and oil derivatives. The study presents the research of formation and survival of static electricity in both reservoirs and tank trucks of different geometric shapes partly filled with oil and oil derivatives. We are proposing a new original possibility of passive elimination of static electricity when loading oil and oil derivatives in reservoirs and tank trucks. The proposed passive device for elimination of static electricity is protected at the international level in the domain of intellectual property (with a patent, model and distinctive mark.

  10. Passive Elimination of Static Electricity in Oil Industry

    Directory of Open Access Journals (Sweden)

    Mićo Gaćanović

    2015-04-01

    Full Text Available This study explains the existing and real conditions of a possible passive elimination of static electricity when loading oil and oil derivatives. We are considering the formation and survival of gas bubbles both in the volume of oil in its depth, but also at the surface of oil and oil derivatives of the partly filled reservoir, and formation of both volume and surface electric charge in oil and oil derivatives. The study presents the research of formation and survival of static electricity in both reservoirs and tank trucks of different geometric shapes partly filled with oil and oil derivatives. We are proposing a new original possibility of passive elimination of static electricity when loading oil and oil derivatives in reservoirs and tank trucks. The proposed passive device for elimination of static electricity is protected at the international level in the domain of intellectual property (with a patent, model and distinctive mark.

  11. HIRENASD Experimental Data, Static Cp Plots and Data files

    Data.gov (United States)

    National Aeronautics and Space Administration — Tecplot (ascii) and matlab files are posted here for the Static pressure coefficient data sets. To download all of the data in either tecplot format or matlab...

  12. Quasi-local energy with respect to a static spacetime

    CERN Document Server

    Chen, Po-Ning; Wang, Ye-Kai; Yau, Shing-Tung

    2016-01-01

    This article considers the quasi-local energy in reference to a general static spacetime. We follow the approach developed by the authors in [19, 20, 7, 9] and define the quasi-local energy as a difference of surface Hamiltonians, which are derived from the Einstein-Hilbert action. The new quasi-local energy provides an effective gauge independent measurement of how far a spacetime deviates away from the reference static spacetime on a finitely extended region.

  13. Static And Kinematic Formulation Of Planar Reciprocal Assemblies

    DEFF Research Database (Denmark)

    Parigi, Dario; Kirkegaard, Poul Henning

    Planar reciprocal frames are two dimensional structures formed by elements joined together according to the principle of structural reciprocity. In this paper a rigorous formulation of the static and kinematic problem is proposed and developed by extending the work on pin-jointed assemblies by...... Pellegrino & Calladine [1986]. This formulation is used to evaluate the static and kinematic determinacy of reciprocal assemblies from the properties of their equilibrium and kinematic matrices....

  14. Static and kinematic formulation of planar reciprocal assemblies

    DEFF Research Database (Denmark)

    Parigi, Dario; Sassone, Mario; Kirkegaard, Poul Henning; Napoli, Paolo

    2014-01-01

    Planar reciprocal frames are two dimensional structures formed by elements joined together according to the principle of structural reciprocity. In this paper a rigorous formulation of the static and kinematic problem is proposed and developed extending the theory of pin-jointed assemblies. This...... formulation is used to evaluate the static and kinematic determinacy of reciprocal assemblies from the properties of their equilibrium and kinematic matrices...

  15. The Einstein static universe in Scalar-Fluid theories

    OpenAIRE

    Boehmer, Christian G.; Tamanini, Nicola; Wright, Matthew

    2015-01-01

    A new Lagrangian framework has recently been proposed to describe interactions between relativistic perfect fluids and scalar fields. In this paper we investigate the Einstein static universe in this new class of theories, which have been named Scalar-Fluid theories. The stability of the static solutions to both homogeneous and inhomogeneous perturbations is analysed deriving the relevant cosmological perturbation equations at the linear order. We can find several configurations corresponding...

  16. Extending Graphic Statics for User-Controlled Structural Morphogenesis

    OpenAIRE

    Fivet, Corentin; Zastavni, Denis; Cap, Jean-François; Structural Morphology Group International Seminar 2011

    2011-01-01

    The first geometrical definitions of any structure are of primary importance when considering pertinence and efficiency in structural design processes. Engineering history has taught us how graphic statics can be a very powerful tool since it allows the designer to take shapes and forces into account simultaneously. However, current and past graphic statics methods are more suitable for analysis than structural morphogenesis. This contribution introduces new graphical methods that can supp...

  17. Static Standing Balance in Adolescents with Down Syndrome

    Science.gov (United States)

    Villarroya, M. Adoracion; Gonzalez-Aguero, Alejandro; Moros-Garcia, Teresa; de la Flor Marin, Mario; Moreno, Luis A.; Casajus, Jose A.

    2012-01-01

    Aim: To analyse static-standing-balance of adolescents with Down syndrome (DS). Methods: Thirty-two adolescents with DS aged 10-19 years (DSG); 33 adolescents, age/sex-matched, without DS (CG). Static-standing-balance under four conditions (C1: open-eyes/fixed-foot-support; C2: closed-eyes/fixed-foot-support; C3: open-eyes/compliant-foot-support;…

  18. Problem Handling and Improvement of Imported SCR Static Excitation System

    Institute of Scientific and Technical Information of China (English)

    Hao Shanwu; Li Weimin; Liang Jianfen; Chu Xue

    2006-01-01

    @@ Static self-excitation system has been more and more widely used for large turbogenerator units in China and achieved very good results in recent years. However, new problems have arisen along with the development of high-power thyristor technology, etc. In view of the actual operating condition of SEE900/5000 SCR static excitation system imported from Siemens, Germany, some technical renovations were carried out.

  19. Static and rotating solutions for Vector-Galileon theories

    CERN Document Server

    Cisterna, Adolfo; Oliva, Julio; Rinaldi, Massimiliano

    2016-01-01

    We consider a particular truncation of the generalized Proca field theory in four dimensions for which we construct a static and axisymmetric rotating black hole "stealth solutions", namely solutions with (Anti) de Sitter or Kerr metric but non-trivial vector field. The static configuration is promoted to a backreacting black hole with asymptotic (Anti) de Sitter behavior by turning on a nonlinear electrodynamic source given as a fixed power of the Maxwell invariant. Finally we extend our solutions to arbitrary dimensions.

  20. Vacuum static compactified wormholes in eight-dimensional Lovelock theory

    OpenAIRE

    Canfora, Fabrizio; Giacomini, Alex

    2008-01-01

    In this paper new exact solutions in eight dimensional Lovelock theory will be presented. These solutions are vacuum static wormhole, black hole and generalized Bertotti-Robinson space-times with nontrivial torsion. All the solutions have a cross product structure of the type $M_{5}\\times \\Sigma_{3} $ where $M_{5}$ is a five dimensional manifold and $\\Sigma_{3}$ a compact constant curvature manifold. The wormhole is the first example of a smooth vacuum static Lovelock wormhole which is neithe...