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Sample records for au-ag alloy static

  1. A facile and green strategy for the synthesis of Au, Ag and Au-Ag alloy nanoparticles using aerial parts of R. hypocrateriformis extract and their biological evaluation.

    Science.gov (United States)

    Godipurge, S S; Yallappa, S; Biradar, Naveen J; Biradar, J S; Dhananjaya, B L; Hegde, Gajanan; Jagadish, K; Hegde, Gurumurthy

    2016-12-01

    A facile and green strategy is reported here to synthesize gold (Au), silver (Ag) and gold-silver (Au-Ag) alloy nanoparticles (NPs) through bio-reduction reactions of aqueous corresponding metal precursors mediated by extracts of aerial parts of R. hypocrateriformis, which act as both reducing and stabilizing agents, under microwave irradiation. UV-vis spectrophotometer, XRD, FT-IR, FESEM/TEM, TGA and EDAX analysis were used to characterize the obtained NPs. The formation of NPs is evident from their surface plasmon resonance peak observed at λmax=∼550, 450 and 500nm for Au, Ag and Au-Ag alloy NPs respectively. XRD pattern revealed that fcc structure, while FT-IR spectra signify the presence of phytochemicals adsorbed on NPs. Such a biofunctionalized NPs were characterized by their weight loss, 30% due to thermal degradation of plant phytochemicals observed in TG analysis. The spherical shape of Au, Ag and Au-Ag alloy NPs (∼10-50nm) is observed by FE-SEM/TEM images. EDAX analysis confirms the expected elemental composition. Moreover, these NPs showed enhanced antimicrobial, antioxidant, and anticancer activities, though it is more pronounced for Au-Ag alloy NPs, which is due to the combining effect of phytochemicals, Au and Ag metals. Thus, the biosynthesized NPs could be applied as effective growth inhibitors for various biomedical applications.

  2. Synthesis of Au-Ag alloy nanoparticles supported on silica gel via galvanic replacement reaction

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Liu; Aiqin Wang; Lin Li; Tao Zhang; Chung-Yuan Mou; Jyh-Fu Lee

    2013-01-01

    Synthesis of supported Au-Ag bimetallic has attracted much attention since we found for the first time that Au and Ag had synergistic effect on CO oxidation and preferential CO oxidation in rich hydrogen. In this work, the formation of Au-Ag alloy nanoparticles supported on silica gel by galvanic replacement reaction has been investigated. We applied various characterizations including X-ray diffraction (XRD), transmission electronic microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), X-ray absorption spectroscopy (XAS) to characterize the formation process of Au-Ag alloy. Although the average particle sizes of the Au-Ag alloy nanoparticles obtained by the galvanic replacement reaction are relatively large comparing with that of loading Au first, the catalytic activity of the catalyst in preferential CO oxidation is almost the same. This result manifested that the particle size effect of Au-Ag nanoparticles was not as tremendous as that of monometallic gold. The formation of Au-Ag alloy made it less sensitive to the particle size.

  3. Surface Plasmon Resonance and Field Enhancement of Au/Ag Alloyed Hollow Nanoshells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li; YU Xue-Feng; FU Xiao-Feng; HAO Zhong-Hua; LI Kai-Yang

    2008-01-01

    We investigate the nanostructure,surface plasmon resonance (SPR) absorption and nonlinear enhancement of Au/Ag alloyed hollow nanoshells prepared by the replacement reaction of Ag nanoparticles in a HAuCl4 aqueous solution.As the volume of HA uCl4 increases from 0 mL to 0.5 mL,the SPR band of the Au/Ag alloyed nanoshells is tuned from 430nm to 780nm,and the third-order nonlinear optical susceptibility is enhanced nearly by an order of magnitude,which indicates a large enhancement of local field in the Au/Ag alloyed hollow nanoshells with hole defects.

  4. 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

    2015-02-25

    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.

  5. 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.

  6. 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.

  7. The Colors and Chromatic Charts of Gold -Silver -Copper Carat Alloys%Au-Ag-Cu系开金合金的颜色与色度图

    Institute of Scientific and Technical Information of China (English)

    宁远涛

    2012-01-01

    颜色和色度坐标是珠宝饰品设计与制造的重要因素与参数.Au- Ag-Cu系合金是最重要的颜色开金饰品合金.文章评述了Ag、Cu对Au和Au基合金的光反射率和颜色的影响;介绍了Au- Ag-Cu系合金的色度图、金合金色泽标准及某些标准颜色合金成分;讨论了某些合金化元素对Au- Ag-Cu系合金颜色的影响.通过调整Ag、Cu组元含量比例和添加其它合金化元素,Au-Ag - Cu系开金合金可以获得丰富多彩的颜色,对于设计与控制珠宝饰品的颜色有重要意义.%Au - Ag - Cu system alloys are the most important color jewelry alloys. The colors of Au - Ag - Cu alloys depend on the composition and the content of the alloying components. The influences of Ag and Cu components on the reflectivity and color of gold and gold - based alloys were reviewed. The chromatic charts of gold - silver - copper carat alloys, color standard of carat alloys and the compositions of some standard color gold alloys were introduced. The effects of some other alloying elements on the color of gold alloys were also discussed. Au - Ag - Cu carat alloys can develop rich and varied colors through regulating the ratio of the contents of Ag and Cu in alloys and adding other alloying elements, which is the basis for designing and controlling colors of carat alloys based on gold.

  8. Growth and morphological analysis of segmented AuAg alloy nanowires created by pulsed electrodeposition in ion-track etched membranes

    Directory of Open Access Journals (Sweden)

    Ina Schubert

    2015-06-01

    Full Text Available Background: Multicomponent heterostructure nanowires and nanogaps are of great interest for applications in sensorics. Pulsed electrodeposition in ion-track etched polymer templates is a suitable method to synthesise segmented nanowires with segments consisting of two different types of materials. For a well-controlled synthesis process, detailed analysis of the deposition parameters and the size-distribution of the segmented wires is crucial.Results: The fabrication of electrodeposited AuAg alloy nanowires and segmented Au-rich/Ag-rich/Au-rich nanowires with controlled composition and segment length in ion-track etched polymer templates was developed. Detailed analysis by cyclic voltammetry in ion-track membranes, energy-dispersive X-ray spectroscopy and scanning electron microscopy was performed to determine the dependency between the chosen potential and the segment composition. Additionally, we have dissolved the middle Ag-rich segments in order to create small nanogaps with controlled gap sizes. Annealing of the created structures allows us to influence their morphology.Conclusion: AuAg alloy nanowires, segmented wires and nanogaps with controlled composition and size can be synthesised by electrodeposition in membranes, and are ideal model systems for investigation of surface plasmons.

  9. Sub-100 nm hollow Au-Ag alloy urchin-shaped nanostructure with ultrahigh density of nanotips for photothermal cancer therapy.

    Science.gov (United States)

    Liu, Zhen; Cheng, Liang; Zhang, Lei; Yang, Zhongbo; Liu, Zhuang; Fang, Jixiang

    2014-04-01

    The 'sea urchin'-like nanostructures with particular small size (photothermal therapy (PTT). Here we report sub-100 nm hollow Au-Ag alloy nanourchins (HAAA-NUs) with ultrahigh density of nanotips synthesized via a facile seed-mediated growth. The HAAA-NUs exhibit a remarkably integrated high-quality photothermal feature including well-defined but tunable surface plasmon resonance peak, strong absorption (2.2 × 10(10) M(-1) cm(-1)) as well as high photothermal conversion efficiency (80.4%) in the near-infrared region. Importantly, the HAAA-NUs demonstrate improved photothermal stability verified via continuous exposition and cyclic irradiation of laser beam. The cell assay, in vitro cell ablation and in vivo breast cancer treatment verify that the HAAA-NUs are superior photothermal agent for photothermal tumor ablation therapy owing to low toxicity and high cell destruction capability.

  10. Synthesis and Optical Properties of Au-Ag Alloy Nanoparticles and Ag@Au Nanoparticles%Au-Ag、Ag@Au纳米颗粒的制备及光学性能的研究

    Institute of Scientific and Technical Information of China (English)

    李婵; 蒋青松

    2015-01-01

    通过改进的Frens法,制备出含金量不同的Au-Ag合金纳米颗粒和Ag@Au纳米颗粒. 通过测试,UV-Vis光谱结果表明,Au-Ag合金纳米颗粒只有一个介于Au、Ag峰值之间的等离子体共振峰;且峰值与金的摩尔分数呈线性关系. SEM、TEM结果表明Ag@Au纳米颗粒有约为13 nm的壳层;而Au-Ag合金纳米颗粒没有核壳结构,说明是合金,并且随着Au-Ag合金中Au的成分的逐渐增加,粒径趋于均匀、形貌趋于稳定的类球型.%Au-Ag alloy nanoparticles and Ag@Au nanoparticles were synthesized by using a modified Frens method. Only one plasmon resonance peak of Au-Ag alloy nanoparticles was observed between that of AuNPS and AgNPS in their UV-Vis spectra and the peak has a near linear relation with the Au content. Due to SEM and TEM ,the apparent Au shell of Ag@Au nanoparticles are about 13 nm,but Au-Ag alloy nanoparticles are lack of core-shell structure. Au-Ag alloy nanoparticles shift to be uniform by increasing the Au content.

  11. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Directory of Open Access Journals (Sweden)

    Hyung-Il Kim

    2013-02-01

    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  12. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Directory of Open Access Journals (Sweden)

    Hyung-Il Kim

    2012-01-01

    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  13. Evaluation of luminol chemiluminescence based on simultaneous introducing of coumarin derivatives as green fluorophores and chitosan-induced Au/Ag alloy nanoparticle as catalyst for the sensitive determination of glucose.

    Science.gov (United States)

    Chaichi, M J; Alijanpour, S O; Asghari, S; Shadlou, S

    2015-03-01

    We report herein the development of a novel chemiluminescence system based on simultaneous introducing of synthetic coumarin derivatives and chitosan-induced Au/Ag alloy NPs on the luminol CL system and suggest how it may be useful for determination of glucose. Chitosan-induced Au/Ag nanoalloys in the coumarin derivatives intensified-luminol CL system, in addition to catalyze CL reaction can make a change in the process of coumarin derivatives effect as fluorophore on the luminol CL system. This phenomenon is caused by interaction between active functional groups of coumarin derivatives and chitosan. The interaction strength depends on the coumarin derivatives' structure and their substituents. Considering the inevitable trend luminol radical and superoxide anion radical to absorption on the surface of the embedded Au/Ag nanoalloy in the chitosan matrix, it can be concluded that chitosan acts as a platform for all reagents involved in the CL reaction including coumarin derivatives, Au/Ag nanoalloy and luminol, and electron-transfer taking place on it; Placing all chemiluminescent reagents together on the chitosan network can lead to a powerful CL due to increasing rigidity of CL system. The most efficient coumarin derivative on the Au/Ag nanoalloy-fluorophore-luminol-H2O2 CL system, in relation to interaction capability with chitosan' functional groups, was selected and the CL condition in presence of it was optimized. Whereas the glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2, under optimum condition the most efficient CL system was applied to detection of glucose due to enzymatically production of hydrogen peroxide. The linear response range of 1.5 × 10(-6)-5.0 × 10(-3) M and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) of 7.5 × 10(-7) M was found for the glucose standards. Also, the developed method was successfully applied to determination of glucose in

  14. Au-Ag合金真空蒸馏分离的理论探讨%Theoretical study on separation of Au-Ag alloy with vacuum distilling

    Institute of Scientific and Technical Information of China (English)

    吴国元; 刘大春

    2005-01-01

    文中比较了Au-Ag 合金中Au、Ag在不同温度下的蒸气压及其蒸气压比值,用分离系数讨论了Au-Ag合金组分真空分离的可能性,并通过计算Au-Ag气液相平衡成分,分析了适合进行真空蒸馏分离的Au-Ag合金成分.

  15. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    Science.gov (United States)

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  16. Influence of the Au/Ag ratio on the catalytic activity of dendrimer-encapsulated bimetallic nanoparticles in microreactors

    NARCIS (Netherlands)

    Ricciardi, R.; Huskens, J.; Verboom, W.

    2015-01-01

    Dendrimer-encapsulated Au/Ag alloy nanoparticles (Au/Ag DENs) were covalently attached to a monolayer-functionalized inner surface of glass microreactors. The influence of the bimetallic alloy structure and of the different metal ratios was investigated for the reduction of 4-nitrophenol using NaBH4

  17. 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.

  18. 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.

  19. Au-Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment.

    Science.gov (United States)

    Jiang, Tongtong; Song, Jiangluqi; Zhang, Wenting; Wang, Hao; Li, Xiaodong; Xia, Ruixiang; Zhu, Lixin; Xu, Xiaoliang

    2015-10-07

    Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents.

  20. 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.

  1. 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.

  2. Hydroquinone-assisted synthesis of branched au-ag nanoparticles with polydopamine coating as highly efficient photothermal agents.

    Science.gov (United States)

    Li, Jing; Wang, Wenjing; Zhao, Liang; Rong, Li; Lan, Shijie; Sun, Hongchen; Zhang, Hao; Yang, Bai

    2015-06-03

    Despite the success of galvanic replacement in preparing hollow nanostructures with diversified morphologies via the replacement reaction between sacrificial metal nanoparticles (NPs) seeds and less active metal ions, limited advances are made for producing branched alloy nanostructures. In this paper, we report an extended galvanic replacement for preparing branched Au-Ag NPs with Au-rich core and Ag branches using hydroquinone (HQ) as the reductant. In the presence of HQ, the preformed Ag seeds are replaceable by Au and, in turn, supply the growth of Ag branches. By altering the feed ratio of Ag seeds, HAuCl4, and HQ, the size and morphology of the NPs are tunable. Accordingly, the surface plasmon resonance absorption is tuned to near-infrared (NIR) region, making the branched NPs as potential materials in photothermal therapy. The branched NPs are further coated with polydopamine (PDA) shell via dopamine polymerization at room temperature. In comparison with bare NPs, PDA-coated branched Au-Ag (Au-Ag@PDA) NPs exhibit improved stability, biocompatibility, and photothermal performance. In vitro experiments indicate that the branched Au-Ag@PDA NPs are competitive agents for photothermal ablation of cancer cells.

  3. Electron beam induced evolution in Au, Ag, and interfaced heterogeneous Au/Ag nanoparticles.

    Science.gov (United States)

    Liu, Yuzi; Sun, Yugang

    2015-08-28

    A sintering process of nanoparticles made of Ag, Au, and interfaced Ag/Au heterodimers was investigated by in situ transmission electron microscopy at room temperature. Such a process is driven by the illumination of a high-energy electron beam accelerated at 200 kV that promotes atom diffusion in the nanoparticles that are in physical contact. Upon electron illumination, adjacent Au nanoparticles gradually merge together to form a larger particle along with the reduction of the surface area despite the fact that orientated attachment is not observed. According to the detailed analysis of the size change of the particles and the contact area, it was found that the nanoparticle fusion process is significantly different from the well-established thermal diffusion mechanism. In addition to the similar fusion process of Au nanoparticles, Ag nanoparticles undergo apparent sublimation induced by knock on damage because the transferred energy from the electron beam to nanoparticles is higher than the surface binding energy of Ag atoms when the electron scattering angle is larger than 112°. The particles with a smaller size diffuse faster. Surface diffusion dominates at the beginning of the fusion process followed by slower lattice diffusion. Electron beam illumination can transform the interfaced Au/Ag dimers to Au@Ag core-shell particles followed by a slow removal of the Ag shells. This process under normal electron beam illumination is a lot faster than the thermally driven process. Both diffusion and sublimation of Ag atoms are dependent on the intensity of the electron beam, i.e., a higher beam intensity is favorable to accelerate both the processes.

  4. Au-Ag hollow nanostructures with tunable SERS properties

    Science.gov (United States)

    Jiji, S. G.; Gopchandran, K. G.

    2017-01-01

    Fabrication of hollow Au-Ag nanoparticles is done by the sequential action of galvanic replacement and Kirkendall effect. Polyol synthesized silver nanoparticles were used as templates and the size of cavities is controlled by the systematic addition of the HAuCl4. Au-Ag nanoparticles carved in different depths were tested for application as substrates for surface enhanced Raman scattering. Two medically important Raman active analytes-Nile blue chloride and Crystal violet were used in the surface enhanced Raman scattering (SERS) performance analysis. A systematic study has been made on the Raman enhancement of hollow nanoparticles fabricated with different cavity dimensions and compared with that of the silver templates used. The enhancement observed for these hollow substrates with cavities is of interest since Au protected hollow nanostructures are vital and an active area of interest in drug delivery systems.

  5. Core-shell Au@Pd nanoparticles with enhanced catalytic activity for oxygen reduction reaction via core-shell Au@Ag/Pd constructions.

    Science.gov (United States)

    Chen, Dong; Li, Chengyin; Liu, Hui; Ye, Feng; Yang, Jun

    2015-07-06

    Core-shell nanoparticles often exhibit improved catalytic properties due to the lattice strain created in these core-shell particles. Herein, we demonstrate the synthesis of core-shell Au@Pd nanoparticles from their core-shell Au@Ag/Pd parents. This strategy begins with the preparation of core-shell Au@Ag nanoparticles in an organic solvent. Then, the pure Ag shells are converted into the shells made of Ag/Pd alloy by galvanic replacement reaction between the Ag shells and Pd(2+) precursors. Subsequently, the Ag component is removed from the alloy shell using saturated NaCl solution to form core-shell Au@Pd nanoparticles with an Au core and a Pd shell. In comparison with the core-shell Au@Pd nanoparticles upon directly depositing Pd shell on the Au seeds and commercial Pd/C catalysts, the core-shell Au@Pd nanoparticles via their core-shell Au@Ag/Pd templates display superior activity and durability in catalyzing oxygen reduction reaction, mainly due to the larger lattice tensile effect in Pd shell induced by the Au core and Ag removal.

  6. Hollow Au-Ag Nanoparticles Labeled Immunochromatography Strip for Highly Sensitive Detection of Clenbuterol

    Science.gov (United States)

    Wang, Jingyun; Zhang, Lei; Huang, Youju; Dandapat, Anirban; Dai, Liwei; Zhang, Ganggang; Lu, Xuefei; Zhang, Jiawei; Lai, Weihua; Chen, Tao

    2017-01-01

    The probe materials play a significant role in improving the detection efficiency and sensitivity of lateral-flow immunochromatographic test strip (ICTS). Unlike conventional ICTS assay usually uses single-component, solid gold nanoparticles as labeled probes, in our present study, a bimetallic, hollow Au-Ag nanoparticles (NPs) labeled ICTS was successfully developed for the detection of clenbuterol (CLE). The hollow Au-Ag NPs with different Au/Ag mole ratio and tunable size were synthesized by varying the volume ratio of [HAuCl4]:[Ag NPs] via the galvanic replacement reaction. The surface of hollow Ag-Au NPs was functionalized with 11-mercaptoundecanoic acid (MUA) for further covalently bonded with anti-CLE monoclonal antibody. Overall size of the Au-Ag NPs, size of the holes within individual NPs and also Au/Ag mole ratio have been systematically optimized to amplify both the visual inspection signals and the quantitative data. The sensitivity of optimized hollow Au-Ag NPs probes has been achieved even as low as 2 ppb in a short time (within 15 min), which is superior over the detection performance of conventional test strip using Au NPs. The optimized hollow Au-Ag NPs labeled test strip can be used as an ideal candidate for the rapid screening of CLE in food samples. PMID:28134263

  7. Hollow Au-Ag Nanoparticles Labeled Immunochromatography Strip for Highly Sensitive Detection of Clenbuterol

    Science.gov (United States)

    Wang, Jingyun; Zhang, Lei; Huang, Youju; Dandapat, Anirban; Dai, Liwei; Zhang, Ganggang; Lu, Xuefei; Zhang, Jiawei; Lai, Weihua; Chen, Tao

    2017-01-01

    The probe materials play a significant role in improving the detection efficiency and sensitivity of lateral-flow immunochromatographic test strip (ICTS). Unlike conventional ICTS assay usually uses single-component, solid gold nanoparticles as labeled probes, in our present study, a bimetallic, hollow Au-Ag nanoparticles (NPs) labeled ICTS was successfully developed for the detection of clenbuterol (CLE). The hollow Au-Ag NPs with different Au/Ag mole ratio and tunable size were synthesized by varying the volume ratio of [HAuCl4]:[Ag NPs] via the galvanic replacement reaction. The surface of hollow Ag-Au NPs was functionalized with 11-mercaptoundecanoic acid (MUA) for further covalently bonded with anti-CLE monoclonal antibody. Overall size of the Au-Ag NPs, size of the holes within individual NPs and also Au/Ag mole ratio have been systematically optimized to amplify both the visual inspection signals and the quantitative data. The sensitivity of optimized hollow Au-Ag NPs probes has been achieved even as low as 2 ppb in a short time (within 15 min), which is superior over the detection performance of conventional test strip using Au NPs. The optimized hollow Au-Ag NPs labeled test strip can be used as an ideal candidate for the rapid screening of CLE in food samples.

  8. Genesis of Middle Miocene Yellowstone hotspot-related bonanza epithermal Au-Ag deposits, Northern Great Basin, USA

    Science.gov (United States)

    Saunders, J. A.; Unger, D. L.; Kamenov, G. D.; Fayek, M.; Hames, W. E.; Utterback, W. C.

    2008-09-01

    heated meteoric water to create precious metal ore-forming fluids. Colloidal nanoparticles of Au-Ag alloy (electrum), naumannite (Ag2Se), silica, and adularia, likely nucleated at depth, traveled upward, and deposited where they grew large enough to aggregate along vein walls. Silica and gold colloids have been reported in hot springs from Yellowstone National Park, suggesting that such processes may continue to some extent to the present. However, it is possible that the initial development of the mantle plume led to a major but short-lived “distillation” process which led to the mid-Miocene bonanza ore-forming event.

  9. Growth of Au@Ag core-shell pentatwinned nanorods: tuning the end facets.

    Science.gov (United States)

    Zhang, Weiqing; Goh, Hao Ying Johnny; Firdoz, Shaik; Lu, Xianmao

    2013-09-16

    Au@Ag core-shell nanorods with tunable end facets are obtained by coating Au bipyramids (BPs) with Ag. The resultant nanorods exhibit a pentatwinned crystal structure with tips terminated with either {110} or {111} facets. The control over the end facets is achieved by varying the capping agents and tuning the reduction rate of Ag. Specifically, when Ag is reduced slowly, Au@Ag nanorods with flat {110} end facets are formed with cetyltrimethylammonium bromide (CTAB) as the capping agent. If CTAB is replaced with cetyltrimethylammonium chloride (CTAC), Au@Ag nanorods with tips terminated with {111} facets are obtained. However, at a high Ag reduction rate, dumbbell-shaped Au@Ag nanorods are formed, with either CTAB or CTAC as the capping agent. The morphological evolution of the nanorods in each case is closely followed and a growth mechanism is proposed.

  10. Growth of various Au Ag nanocomposites from gold seeds in amino acid solutions

    Science.gov (United States)

    Huang, Yu-Fen; Lin, Yang-Wei; Chang, Huan-Tsung

    2006-10-01

    In this paper, we describe an easy procedure for the preparation of differently shaped and sized Au-Ag nanocomposites from gold nanorod (AuNR) seeds in various amino acid solutions—arginine (Arg), cysteine (Cys), glycine (Gly), glutamate (Glu), glutamine (Gln), histidine (His), lysine (Lys), and methionine (Met), respectively—at values of pH ranging from 8.0 to 11.5. Our results suggest that the pH, the nature of the amino acid, and its concentration all have significant impact on the preparation of Au-Ag nanocomposites; these factors exhibit their effects mainly through control over the reducing ability of ascorbate and/or its recognition capability, as well as through control over the surface charges of the amino acids on the AuNRs. Depending on the value of pH, we were able to prepare I-shaped, dumbbell-shaped, and/or sphere-shaped Au-Ag nanocomposites in 0.1 M solutions of Arg, Gly, Glu, Gln, Lys, and Met. In His solutions at pH 8.0 and 9.0, we obtained peanut-shaped Au-Ag nanocomposites. Corn-shaped Au-Ag nanocomposites were prepared in 0.1 M Met solutions (pH 9.0 and 10.0). By controlling the Lys concentration at pH 10.0, we synthesized pearl-necklace-shaped Au-Ag nanoparticles and Au-Ag wires. Based on the TEM images, we conclude that this simple and reproducible synthetic approach allows preparation of high-quality (>87%, beside>77% in His solutions) Au-Ag nanocomposites with various shapes and sizes under different conditions.

  11. Growth of various Au-Ag nanocomposites from gold seeds in amino acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y-F [Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, Taiwan (China); Lin, Y-W [Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, Taiwan (China); Chang, H-T [Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, Taiwan (China)

    2006-10-14

    In this paper, we describe an easy procedure for the preparation of differently shaped and sized Au-Ag nanocomposites from gold nanorod (AuNR) seeds in various amino acid solutions-arginine (Arg), cysteine (Cys), glycine (Gly), glutamate (Glu), glutamine (Gln), histidine (His), lysine (Lys), and methionine (Met), respectively-at values of pH ranging from 8.0 to 11.5. Our results suggest that the pH, the nature of the amino acid, and its concentration all have significant impact on the preparation of Au-Ag nanocomposites; these factors exhibit their effects mainly through control over the reducing ability of ascorbate and/or its recognition capability, as well as through control over the surface charges of the amino acids on the AuNRs. Depending on the value of pH, we were able to prepare I-shaped, dumbbell-shaped, and/or sphere-shaped Au-Ag nanocomposites in 0.1 M solutions of Arg, Gly, Glu, Gln, Lys, and Met. In His solutions at pH 8.0 and 9.0, we obtained peanut-shaped Au-Ag nanocomposites. Corn-shaped Au-Ag nanocomposites were prepared in 0.1 M Met solutions (pH 9.0 and 10.0). By controlling the Lys concentration at pH 10.0, we synthesized pearl-necklace-shaped Au-Ag nanoparticles and Au-Ag wires. Based on the TEM images, we conclude that this simple and reproducible synthetic approach allows preparation of high-quality (>87%, beside>77% in His solutions) Au-Ag nanocomposites with various shapes and sizes under different conditions.

  12. Nanoporous Au structures by dealloying Au/Ag thermal- or laser-dewetted bilayers on surfaces

    Science.gov (United States)

    Ruffino, F.; Torrisi, V.; Grillo, R.; Cacciato, G.; Zimbone, M.; Piccitto, G.; Grimaldi, M. G.

    2017-03-01

    Nanoporous Au attracts great technological interest and it is a promising candidate for optical and electrochemical sensors. In addition to nanoporous Au leafs and films, recently, interest was focused on nanoporous Au micro- and nano-structures on surfaces. In this work we report on the study of the characteristics of nanoporous Au structures produced on surfaces. We developed the following procedures to fabricate the nanoporous Au structures: we deposited thin Au/Ag bilayers on SiO2 or FTO (fluorine-doped tin oxide) substrates with thickness xAu and xAg of the Au and Ag layers; we induced the alloying and dewetting processes of the bilayers by furnace annealing processes of the bilayers deposited on SiO2 and by laser irradiations of the bilayers deposited on FTO; the alloying and dewetting processes result in the formation of AuxAgy alloy sub-micron particles being x and y tunable by xAu and xAg. These particles are dealloyed in HNO3 solution to remove the Ag atoms. We obtain, so, nanoporous sub-micron Au particles on the substrates. Analyzing the characteristics of these particles we find that: a) the size and shape of the particles depend on the nature of the dewetting process (solid-state dewetting on SiO2, molten-state dewetting on FTO); b) the porosity fraction of the particles depends on how the alloying process is reached: about 32% of porosity for the particles fabricated by the furnace annealing at 900 °C, about 45% of porosity for the particles fabricated by the laser irradiation at 0.5 J/cm2, in both cases independently on the Ag concentration in the alloy; c) After the dealloying process the mean volume of the Au particles shrinks of about 39%; d) After an annealing at 400 °C the nanoporous Au particles reprise their initial volume while the porosity fraction is reduced. Arguments to justify these behaviors are presented.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Onset of Intense Surface Enhanced Raman Scattering and Aggregation in the Au@Ag System

    Directory of Open Access Journals (Sweden)

    Priya Bhatia

    2015-01-01

    Full Text Available Gold core/silver shell (Au@Ag nanoparticles of ~37 ± 5 nm diameter generate intense SERS (λEX=785 nm responses in solution when they interact with the SERS labels rhodamine 6G (R6G, 4-mercaptopyridine (MPY, and 4-mercaptobenzoic acid (MBA. Herein the relationship between SERS intensity, aggregation, and adsorption phenomenon isobserved by titrating Au@Ag with the above labels. As the labels adsorb to the Au@Ag, they drive aggregation as evidenced by the creation of NIR extinction peaks, and the magnitude of this NIR extinction (measured at 830 nm correlates very closely to magnitude of the intense SERS signals. The label MBA is an exception since it does not trigger aggregation nor does it result in intense SERS; rather intense SERS is recovered only after MBA coated Au@Ag is aggregated with KCl. An “inner filter” model is introduced and applied to compensate for solution extinction when the exciting laser radiation is significantly attenuated. This model permits a summary of the SERS responses in the form of plots of SERS intensity versus the aggregate absorption at 830 nm, which shows the excellent correlation between intense SERS and LSPR bands extinction.

  18. Surface conduction at phase transitions in (Au,Ag)/Si(1 1 1) submonolayer films

    Energy Technology Data Exchange (ETDEWEB)

    Tsukanov, D.A., E-mail: tsukanov@iacp.dvo.ru [Institute of Automation and Control Processes, FEB RAS, Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Ryzhkova, M.V.; Borisenko, E.A. [Institute of Automation and Control Processes, FEB RAS, Vladivostok 690041 (Russian Federation); Bondarenko, L.V.; Matetskiy, A.V.; Gruznev, D.V. [Institute of Automation and Control Processes, FEB RAS, Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes, FEB RAS, Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Vladivostok 690950 (Russian Federation); Vladivostok State University of Economics and Service, Vladivostok 690600 (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes, FEB RAS, Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Vladivostok 690950 (Russian Federation)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Structural reordering occurs upon Ag adsorption onto Si(1 1 1){alpha}-{radical}3 Multiplication-Sign {radical}3-Au surface phase at 350 Degree-Sign C. Black-Right-Pointing-Pointer The new surface structure identified as Si(1 1 1){radical}93 Multiplication-Sign {radical}93-(Au,Ag) has been found by LEED and STM. Black-Right-Pointing-Pointer Electrical conductivity of various (Au,Ag)/Si(1 1 1) nanostructures has been characterized. - Abstract: Surface structure and electrical conductance of the (Au,Ag)/Si(1 1 1) two-dimensional system have been studied in situ with low-energy electron diffraction, scanning tunneling microscopy and four-point probe technique. The new surface structure identified as Si(1 1 1){radical}93 Multiplication-Sign {radical}93-(Au,Ag) has been found to form upon deposition of {approx}0.1 ML of Ag onto Si(1 1 1){alpha}-{radical}3 Multiplication-Sign {radical}3-Au surface held at 350 Degree-Sign C. With further Ag deposition at this growth temperature, the surface structure evolves to Si(1 1 1)2{radical}3 Multiplication-Sign 2{radical}3 and eventually to Si(1 1 1){radical}21 Multiplication-Sign {radical}21. Structural transformations have been found to be accompanied by non-monotonous changeover of the surface conductance. Possible factors affecting the surface conductivity are discussed.

  19. 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.

  20. Green synthesis and applications of Au-Ag bimetallic nanoparticles.

    Science.gov (United States)

    Meena Kumari, M; Jacob, John; Philip, Daizy

    2015-02-25

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenolnanoparticles enhances the thermal conductivity of the base fluid (water) showing nanofluid application. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field.

  1. Static immersion and irritation tests of dental metal-ceramic alloys.

    Science.gov (United States)

    Ardlin, Berit I; Dahl, Jon E; Tibballs, John E

    2005-02-01

    The expansion of the European Union is bringing new types of metal-ceramic alloys to the market, i.e. alloys probably unknown in Western-European dentistry. The aim of this study was to investigate recent developments and "classic" alloy compositions (one iron and two cobalt alloys, unalloyed titanium and an experimental titanium-zirconium alloy, and one gold alloy containing copper and zinc). The alloys and titanium were subject to static immersion in a 0.1 mol l(-1) solution of saline lactic acid before and after oxidation, hence simulating the temperature cycles for the application of ceramic to metal. The greatest amounts of released metal ions were found in the electrolytes of the oxidized gold alloy and of a cobalt alloy not exposed to high-temperature oxidation. Corrosion of the titanium and alloy surfaces was related to the condition of the specimen. The irritation potentials of some metal ions found in the electrolyte were investigated by performing the hen's egg test-chorio-allantoic membrane (HET-CAM) procedure with 1 mmol l(-1) solutions of Ce(3+), Co(2+), Cu(2+), Zn(2+), Fe(2+), and Ti(4+) ions. The irritation potential of the electrolyte of the oxidized gold alloy with a high concentration of metal elements was also investigated. Of these solutions, only the 1 mmol l(-1) Cu(2+) solution was graded as slightly irritating.

  2. Shell Thickness-Dependent Strain Distributions of Confined Au/Ag and Ag/Au Core-Shell Nanoparticles

    OpenAIRE

    Feng Liu; Honghua Huang; Ying Zhang; Ting Yu; Cailei Yuan; Shuangli Ye

    2015-01-01

    The shell thickness-dependent strain distributions of the Au/Ag and Ag/Au core-shell nanoparticles embedded in Al2O3 matrix have been investigated by finite element method (FEM) calculations, respectively. The simulation results clearly indicate that there is a substantial strain applied on both the Au/Ag and Ag/Au core-shell nanoparticles by the Al2O3 matrix. For the Au/Ag nanoparticles, it can be found that the compressive strain existing in the shell is stronger than that on the center of ...

  3. Polymer Film Supported Bimetallic Au-Ag Catalysts for Electrocatalytic Oxidation of Ammonia Borane in Alkaline Media

    Institute of Scientific and Technical Information of China (English)

    Şükriye Ulubay Karabiberoglu; ÇagrCeylan Koçak; Süleyman Kocak; Zekerya Dursun

    2016-01-01

    Ammonia borane is widely used in most areas including fuel cell applications. The present paper describes electrochemical behavior of ammonia borane in alkaline media on the poly(p-aminophenol) film modified with Au and Ag bimetallic nanoparticles. The glassy carbon electrode was firstly covered with polymeric film electrochemically and then, Au, Ag, and Au–Ag nanoparticles were deposited on the polymeric film, respectively. The surface morphology and chemical composition of these electrodes were examined by scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It was found that alloyed Au–Ag bimetallic nanoparticles are formed. Electrochemical measurements indicate that the developed electrode modified by Au–Ag bimetallic nanoparticles exhibit the highest electrocatalytic activity for ammonia borane oxidation in alkaline media. The rotating disk electrode voltammetry demonstrates that the developed electrode can catalyze almost six-electron oxidation pathway of ammonia borane. Our results may be attractive for anode materials of ammonia borane fuel cells under alkaline conditions.

  4. 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.

  5. 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

  6. Effects of zinc on static and dynamic mechanical properties of copper-zinc alloy

    Institute of Scientific and Technical Information of China (English)

    马志超; 赵宏伟; 鲁帅; 程虹丙

    2015-01-01

    The effects of adding alloy element zinc on the static and dynamic mechanical properties of copper-zinc alloy were investigated. Tensile and low cycle fatigue behaviors of the C11000 copper and H63 copper-zinc alloy were obtained by using a miniature tester that combined the functions of in situ tensile and fatigue testing. A piezoelectric actuator was adopted as the actuator for the fatigue testing, and the feasibility of the fatigue actuator was verified by the transient harmonic response analysis based on static tensile preload and dynamic sinusoidal load. The experimental results show that the yield strength and tensile strength of the C11000 copper are improved after adding 37% (mass fraction) zinc, and H63 copper-zinc alloy presents more obvious cyclic hardening behavior and more consumed irreversible plastic work during each stress cycle compared with C11000 copper for the same strain controlled cycling. Additionally, based on the Manson-Coffin theory, the strain-life equations of the two materials were also obtained. C11000 copper and H63 copper-zinc alloy show transition life of 16832 and 1788 cycles, respectively.

  7. 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

  8. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    Science.gov (United States)

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future.

  9. 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 geothermal circulation along N-S structural fabric driven by heat from rhyolite domes; ~16.34 Ma, emplacement of NW trending basalt dikes, followed by violent

  10. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-15

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

  12. 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.

  13. Hybrid microfluidic fuel cell based on Laccase/C and AuAg/C electrodes.

    Science.gov (United States)

    López-González, B; Dector, A; Cuevas-Muñiz, F M; Arjona, N; Cruz-Madrid, C; Arana-Cuenca, A; Guerra-Balcázar, M; Arriaga, L G; Ledesma-García, J

    2014-12-15

    A hybrid glucose microfluidic fuel cell composed of an enzymatic cathode (Laccase/ABTS/C) and an inorganic anode (AuAg/C) was developed and tested. The enzymatic cathode was prepared by adsorption of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Laccase on Vulcan XC-72, which act as a redox mediator, enzymatic catalyst and support, respectively. The Laccase/ABTS/C composite was characterised by Fourier Transform Infrared (FTIR) Spectroscopy, streaming current measurements (Zeta potential) and cyclic voltammetry. The AuAg/C anode catalyst was characterised by Transmission electron microscopy (TEM) and cyclic voltammetry. The hybrid microfluidic fuel cell exhibited excellent performance with a maximum power density value (i.e., 0.45 mW cm(-2)) that is the highest reported to date. The cell also exhibited acceptable stability over the course of several days. In addition, a Mexican endemic Laccase was used as the biocathode electrode and evaluated in the hybrid microfluidic fuel cell generating 0.5 mW cm(-2) of maximum power density.

  14. 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.

  15. Endogenic Au-Ag polymetallic ore deposits and ore-bearing potentiality of strata

    Institute of Scientific and Technical Information of China (English)

    WANG Baode; NIU Shuyin; SUN Aiqun; XIE Yan; LUO Yi; LIU Hailong; WANG Yanhua

    2010-01-01

    The problem of ore-bearing potentiality of the strata involves metallogenic theory and ore-search orientation. Studies of the spatial distribution of endogenic Au-Ag polymetallic ore deposits in North Hebei indicated that the strata in which ore deposits occurred range in age from Paleozoic, Proterozoic to Mesozoic. In addition the ore deposits are characterized as being strata-bound in nature. The arise and establishment of "extracting" viewpoint may be attributed to the following three reasons: 1) influence by the idea of "ore-source bed"; 2) limitation of analytical techniques in the 1980s' (especially gold element); and 3) a small number of samples (sampling locations were mostly disturbed by mineralization). Studies have shown that ore-forming materials would most probably come from the deep interior of the Earth. Deep-seated ore-bearing materials including Au-Ag polymetals were brought to the shallow levels by way of mantle plume-mantle sub-plume-mantle branch structure multi-stage evolution, finally leading to the formation of ore deposits.

  16. Synthesis, fractionation, and optical characterization of Au-Ag composite nanorods

    Science.gov (United States)

    Alekseeva, Anna V.; Bogatyrev, Vladimir A.; Trachuk, Lyubov A.; Khlebtsov, Nikolai G.

    2005-06-01

    We report on a synthesis procedure and optical properties of composite Au-Ag spherical and rod-like nanoparticles. The synthesis protocol is based on a seed-mediated growth in the presence of soft templates in micellar aqueous solution of ionic surfactant (CTAB). Variation of Au/Ag molar ratio allows one to produce nanorods (NRs) with different aspect ratio. The disadvantage of the method is formation of appreciable amount of spherical nanoparticles. To separate rod-like particles from spheres and surfactant, we used a fractionation procedure that involves centrifugatiori of samples in the density gradient of glycerol. The separated NRs were suspended in water or 25% glycerol solutions and their extinction and differential light scattering (at 900) spectra were recorded for 450-850 ni-n wavelengths. Theoretical spectra were calculated by T-matrix method as applied to randomly oriented gold cylinders with semispherical ends. The simulated spectra for water and glycerol suspensions can be brought in close agreement with experimental observations if the aspect ratio is used as a fitting parameter. We discuss also the absorption and light scattering contribution to the total extinction spectra and deviation of the exact solution from the classical electrostatic approximation by Gans.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Jianlong; Li, Pengwei; Sang, Shengbo, E-mail: sbsang@tyut.edu.cn; Zhang, Wendong, E-mail: wdzhang@tyut.edu.cn; Li, Gang; Hu, Jie [Micro and Nano-system Research Centre, College of Information Engineering, Taiyuan University of Technology, 030024, Taiyuan (China); Zhou, Zhaoying, E-mail: zhouzy@mail.tsinghua.edu.cn; Yang, Xing; Dong, Hualai [MEMS Laboratory, Department of Precision Instruments, Tsinghua University, 100084, Beijing (China)

    2014-03-15

    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.

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

    Science.gov (United States)

    Ji, Jianlong; Li, Pengwei; Sang, Shengbo; Zhang, Wendong; Zhou, Zhaoying; Yang, Xing; Dong, Hualai; Li, Gang; Hu, Jie

    2014-03-01

    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.

  19. Laser nanostructuring of Au/Ag and Au/Ni films for application in SERS

    Science.gov (United States)

    Nikov, Ru. G.; Nedyalkov, N. N.; Atanasov, P. A.; Grochowska, K.; Iwulska, A.; Sliwinski, G.

    2013-03-01

    In this paper results on laser nanostructuring of Au/Ag and Au/Ni thin films are presented. The nanostructuring leads to formation of arrays of bimetallic nanoparticles. The fabrication of the these structures is made using a two step procedure. Initially, thin films are deposited on quartz substrates by classical pulsed laser deposition method. In order to produce Au/Ag or Au/Ni thin films, targets with two sections consist the different metals are used. Thin films with different concentrations of the two metals are obtained by changing the area of the different sections in the target. The as prepared films are then annealed by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. It is found that the laser annealing may lead to nanostructuring of the deposited films as at certain conditions decomposition into monolayers of nanoparticles with narrow size distribution is obtained. The performed EDX analyses indicate that the fabricated particles are composed by a bimetallic system of the basic metals used. The transmission spectra of the obtained structures show evidences of plasmon excitations. The bimetal nanostructures are covered with Rhodamine 6G and then tested as active substrates for Surface Enhanced Raman Spectroscopy (SERS).

  20. A colorimetric assay for measuring iodide using Au@Ag core–shell nanoparticles coupled with Cu{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Jingbin, E-mail: xmuzjb@163.com [State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555 (China); Cao, Yingying [State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555 (China); Lu, Chun-Hua [The Key Laboratory of Analysis and Detection Technology for Food Safety of the MOE, College of Chemistry, Fuzhou University, Fuzhou 350002 (China); Wang, Xu-dong [Karlsruhe Institute of Technology (KIT), Institute for Biological Interfaces (IBG-1), Hermann-von-Helmholtz-Platz, 76344 Eggenstein-Leopoldshafen (Germany); Wang, Qianru; Wen, Cong-ying; Qu, Jian-Bo; Yuan, Cunguang [State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555 (China); Yan, Zi-feng, E-mail: zfyancat@upc.edu.cn [State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555 (China); Chen, Xi [Department of Chemistry and the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2015-09-03

    Au@Ag core–shell nanoparticles (NPs) were synthesized and coupled with copper ion (Cu{sup 2+}) for the colorimetric sensing of iodide ion (I{sup −}). This assay relies on the fact that the absorption spectra and the color of metallic core–shell NPs are sensitive to their chemical ingredient and dimensional core-to-shell ratio. When I{sup −} was added to the Au@Ag core–shell NPs-Cu{sup 2+} system/solution, Cu{sup 2+} can oxidize I{sup −} into iodine (I{sub 2}), which can further oxidize silver shells to form silver iodide (AgI). The generated Au@AgI core–shell NPs led to color changes from yellow to purple, which was utilized for the colorimetric sensing of I{sup −}. The assay only took 10 min with a lowest detectable concentration of 0.5 μM, and it exhibited excellent selectivity for I{sup −} over other common anions tested. Furthermore, Au@Ag core–shell NPs-Cu{sup 2+} was embedded into agarose gels as inexpensive and portable “test strips”, which were successfully used for the semi-quantitation of I{sup −} in dried kelps. - Highlights: • Au@Ag core–shell NPs were synthesized and coupled with Cu{sup 2+} for the colorimetric I{sup −} sensing. • This assay is simple, rapid and selective. • Au@Ag core–shell NPs-Cu{sup 2+} were embedded into agarose gels as test strips.

  1. Fabrication of Au@Ag core/shell nanoparticles decorated TiO2 hollow structure for efficient light-harvesting in dye-sensitized solar cells.

    Science.gov (United States)

    Yun, Juyoung; Hwang, Sun Hye; Jang, Jyongsik

    2015-01-28

    Improving the light-harvesting properties of photoanodes is promising way to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). We synthesized Au@Ag core/shell nanoparticles decorated TiO2 hollow nanoparticles (Au@Ag/TiO2 HNPs) via sol-gel reaction and chemical deposition. The Au@Ag/TiO2 HNPs exhibited multifunctions from Au@Ag core/shell NPs (Au@Ag CSNPs) and TiO2 hollow nanoparticles (TiO2 HNPs). These Au@Ag CSNPs exhibited strong and broadened localized surface plasmon resonance (LSPR), together with a large specific surface area of 129 m(2) g(-1), light scattering effect, and facile oxidation-reduction reaction of electrolyte from TiO2 HNPs, which resulted in enhancement of the light harvesting. The optimum PCE of η = 9.7% was achieved for the DSSCs using photoanode materials based on TiO2 HNPs containing Au@Ag/TiO2 HNPs (0.2 wt % Au@Ag CSNPs with respect to TiO2 HNPs), which outperformed by 24% enhancement that of conventional photoanodes formed using P25 (η = 7.8%).

  2. Dynamic and quasi-static mechanical properties of iron-nickel alloy honeycomb

    Science.gov (United States)

    Clark, Justin L.

    Several metal honeycombs, termed Linear Cellular Alloys (LCAs), were fabricated via a paste extrusion process and thermal treatment. Two Fe-Ni based alloy compositions were evaluated. Maraging steel and Super Invar were chosen for their compatibility with the process and the wide range of properties they afforded. Cell wall material was characterized and compared to wrought alloy specifications. The bulk alloy was found to compare well with the more conventionally produced wrought product when porosity was taken into account. The presence of extrusion defects and raw material impurities were shown to degrade properties with respect to wrought alloys. The performance of LCAs was investigated for several alloys and cell morphologies. The results showed that out-of-plane properties exceeded model predictions and in-plane properties fell short due to missing cell walls and similar defects. Strength was shown to outperform several existing cellular metals by as much as an order of magnitude in some instances. Energy absorption of these materials was shown to exceed 150 J/cc at strains of 50% for high strength alloys. Finally, the suitability of LCAs as an energetic capsule was investigated. The investigation found that the LCAs added significant static strength and as much as three to five times improvement in the dynamic strength of the system. More importantly, it was shown that the pressures achieved with the LCA capsule were significantly higher than the energetic material could achieve alone. High pressures, approaching 3 GPa, coupled with the fragmentation of the capsule during impact increased the likelihood of initiation and propagation of the energetic reaction. This multi-functional aspect of the LCA makes it a suitable capsule material.

  3. A nanocomposite of Au-AgI core/shell dimer as a dual-modality contrast agent for x-ray computed tomography and photoacoustic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Orza, Anamaria; Wu, Hui; Li, Yuancheng; Mao, Hui, E-mail: hmao@emory.edu, E-mail: Xiangyang.Tang@emory.edu [Department of Radiology and Imaging Sciences and Center for Systems Imaging, Emory University School of Medicine, Atlanta, Georgia 30322 (United States); Yang, Yi; Tang, Xiangyang, E-mail: hmao@emory.edu, E-mail: Xiangyang.Tang@emory.edu [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30322 (United States); Feng, Ting; Wang, Xueding [Department of Biomedical Engineering, University of Michigan School of Medicine, Ann Arbor, Michigan 48109 (United States); Yang, Lily [Department of Surgery, Emory University School of Medicine, Atlanta, Georgia 30322 (United States)

    2016-01-15

    Purpose: To develop a core/shell nanodimer of gold (core) and silver iodine (shell) as a dual-modal contrast-enhancing agent for biomarker targeted x-ray computed tomography (CT) and photoacoustic imaging (PAI) applications. Methods: The gold and silver iodine core/shell nanodimer (Au/AgICSD) was prepared by fusing together components of gold, silver, and iodine. The physicochemical properties of Au/AgICSD were then characterized using different optical and imaging techniques (e.g., HR- transmission electron microscope, scanning transmission electron microscope, x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, Z-potential, and UV-vis). The CT and PAI contrast-enhancing effects were tested and then compared with a clinically used CT contrast agent and Au nanoparticles. To confer biocompatibility and the capability for efficient biomarker targeting, the surface of the Au/AgICSD nanodimer was modified with the amphiphilic diblock polymer and then functionalized with transferrin for targeting transferrin receptor that is overexpressed in various cancer cells. Cytotoxicity of the prepared Au/AgICSD nanodimer was also tested with both normal and cancer cell lines. Results: The characterizations of prepared Au/AgI core/shell nanostructure confirmed the formation of Au/AgICSD nanodimers. Au/AgICSD nanodimer is stable in physiological conditions for in vivo applications. Au/AgICSD nanodimer exhibited higher contrast enhancement in both CT and PAI for dual-modality imaging. Moreover, transferrin functionalized Au/AgICSD nanodimer showed specific binding to the tumor cells that have a high level of expression of the transferrin receptor. Conclusions: The developed Au/AgICSD nanodimer can be used as a potential biomarker targeted dual-modal contrast agent for both or combined CT and PAI molecular imaging.

  4. 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

  5. Au@Ag core-shell nanocubes for efficient plasmonic light scattering effect in low bandgap organic solar cells.

    Science.gov (United States)

    Baek, Se-Woong; Park, Garam; Noh, Jonghyeon; Cho, Changsoon; Lee, Chun-Ho; Seo, Min-Kyo; Song, Hyunjoon; Lee, Jung-Yong

    2014-04-22

    In this report, we propose a metal-metal core-shell nanocube (NC) as an advanced plasmonic material for highly efficient organic solar cells (OSCs). We covered an Au core with a thin Ag shell as a scattering enhancer to build Au@Ag NCs, which showed stronger scattering efficiency than Au nanoparticles (AuNPs) throughout the visible range. Highly efficient plasmonic organic solar cells were fabricated by embedding Au@Ag NCs into an anodic buffer layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and the power conversion efficiency was enhanced to 6.3% from 5.3% in poly[N-9-hepta-decanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (PCDTBT):[6,6]-phenyl C71-butyric acid methyl ester (PC70BM) based OSCs and 9.2% from 7.9% in polythieno[3,4-b]thiophene/benzodithiophene (PTB7):PC70BM based OSCs. The Au@Ag NC plasmonic PCDTBT:PC70BM-based organic solar cells showed 2.2-fold higher external quantum efficiency enhancement compared to AuNPs devices at a wavelength of 450-700 nm due to the amplified plasmonic scattering effect. Finally, we proved the strongly enhanced plasmonic scattering efficiency of Au@Ag NCs embedded in organic solar cells via theoretical calculations and detailed optical measurements.

  6. 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...

  7. [Au]/[Ag]-catalysed expedient synthesis of branched heneicosafuranosyl arabinogalactan motif of Mycobacterium tuberculosis cell wall

    Science.gov (United States)

    Thadke, Shivaji A.; Mishra, Bijoyananda; Islam, Maidul; Pasari, Sandip; Manmode, Sujit; Rao, Boddu Venkateswara; Neralkar, Mahesh; Shinde, Ganesh P.; Walke, Gulab; Hotha, Srinivas

    2017-01-01

    Emergence of multidrug-resistant and extreme-drug-resistant strains of Mycobacterium tuberculosis (MTb) can cause serious socioeconomic burdens. Arabinogalactan present on the cellular envelope of MTb is unique and is required for its survival; access to arabinogalactan is essential for understanding the biosynthetic machinery that assembles it. Isolation from Nature is a herculean task and, as a result, chemical synthesis is the most sought after technique. Here we report a convergent synthesis of branched heneicosafuranosyl arabinogalactan (HAG) of MTb. Key furanosylations are performed using [Au]/[Ag] catalysts. The synthesis of HAG is achieved by the repetitive use of three reactions namely 1,2-trans furanoside synthesis by propargyl 1,2-orthoester donors, unmasking of silyl ether, and conversion of n-pentenyl furanosides into 1,2-orthoesters. Synthesis of HAG is achieved in 47 steps (with an overall yield of 0.09%) of which 21 are installation of furanosidic linkages in a stereoselective manner. PMID:28120821

  8. Effect of Chromium Interlayer Thickness on Optical Properties of Au-Ag Nanoparticle Array

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2014-01-01

    Full Text Available The effect of chromium interlayer thickness on optical properties of array of hybrid Au-Ag triangular nanoparticles is systematically investigated. The optical spectrum simulated by discrete dipole approximation (DDA numerical method shows that with increase of the chromium interlayer thickness both refractive index sensitivity (RIS and figure of merit (FOM of localized surface plasmon resonance from the hybrid nanostructures experience remarkable change and the intensity of the extinction efficiency decreases. The nanosphere lithography (NSL is used to fabricate the hybrid nanostructure arrays with different chromium interlayer thicknesses. The experiment demonstrates that the spectrum as measured from the as-fabricated hybrid nanostructure arrays is essentially in agreement with the simulated results.

  9. [Au]/[Ag]-catalysed expedient synthesis of branched heneicosafuranosyl arabinogalactan motif of Mycobacterium tuberculosis cell wall

    Science.gov (United States)

    Thadke, Shivaji A.; Mishra, Bijoyananda; Islam, Maidul; Pasari, Sandip; Manmode, Sujit; Rao, Boddu Venkateswara; Neralkar, Mahesh; Shinde, Ganesh P.; Walke, Gulab; Hotha, Srinivas

    2017-01-01

    Emergence of multidrug-resistant and extreme-drug-resistant strains of Mycobacterium tuberculosis (MTb) can cause serious socioeconomic burdens. Arabinogalactan present on the cellular envelope of MTb is unique and is required for its survival; access to arabinogalactan is essential for understanding the biosynthetic machinery that assembles it. Isolation from Nature is a herculean task and, as a result, chemical synthesis is the most sought after technique. Here we report a convergent synthesis of branched heneicosafuranosyl arabinogalactan (HAG) of MTb. Key furanosylations are performed using [Au]/[Ag] catalysts. The synthesis of HAG is achieved by the repetitive use of three reactions namely 1,2-trans furanoside synthesis by propargyl 1,2-orthoester donors, unmasking of silyl ether, and conversion of n-pentenyl furanosides into 1,2-orthoesters. Synthesis of HAG is achieved in 47 steps (with an overall yield of 0.09%) of which 21 are installation of furanosidic linkages in a stereoselective manner.

  10. Tunable Au-Ag nanobowl arrays for size-selective plasmonic biosensing.

    Science.gov (United States)

    Jana, Debrina; Lehnhoff, Emily; Bruzas, Ian; Robinson, Jendai; Lum, William; Sagle, Laura

    2016-08-01

    Selectivity is often a major obstacle for localized surface plasmon resonance-based biosensing in complex biological solutions. An additional degree of selectivity can be achieved through the incorporation of shape complementarity on the nanoparticle surface. Here, we report the versatile fabrication of substrate-bound Au-Ag nanobowl arrays through the galvanic ion replacement of silver nanodisk arrays. Both localized surface plasmon resonance (LSPR) and surface enhanced Raman spectroscopy (SERS) were carried out to detect the binding of analytes of varying size to the nanobowl arrays. Large increases in the LSPR and SERS response were measured for analytes that were small enough to enter the nanobowls, compared to those too large to come into contact with the interior of the nanobowls. This size-selective sensing should prove useful in both size determination and differentiation of large analytes in biological solutions, such as viruses, fungi, and bacterial cells.

  11. 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.

  12. RETRACTED: One-step synthesis of Au-Ag alloy nanoparticles by a convenient electrochemical method

    Science.gov (United States)

    Zhou, Min; Chen, Shenhao; Zhao, Shiyong; Ma, Houyi

    2006-06-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editors of Physica E: Low-Dimensional Systems and Nanostructures together with the corresponding author of the article because after thorough investigation it now appears that in this article some pictures are wrong and data contain mistakes.The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

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

    Science.gov (United States)

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

    2004-08-04

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

  14. 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.

  15. 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

  16. 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.

  17. Study of delta phase on static recrystallization behavior of Inconel 718 alloy.

    Science.gov (United States)

    Lee, Hwa-Teng; Hou, Wen-Hsin

    2012-09-01

    The mechanical properties of Inconel 718 alloy depend on its microstructural features. Controlling the grain size during manufacturing is currently achieved through the use of a powerful hot forming process performed at a temperature sufficiently high to induce dynamic recrystallization. The present study proposes an alternative technique to achieve a uniform fine grain structure by using static recrystallization and a proper control of delta precipitation. The results show that a fine structure with an average grain size of ASTM No. 7 can be achieved. And in this study the finest grains yet achievable is ca. 200 nm. As a result, the proposed technique provides a feasible means of controlling the grain size without the need for an energy consumption and technically sophisticated hot forming process.

  18. Finite element analysis of stiffness and static dent resistance of aluminum alloy double-curved panel in viscous pressure forming

    Institute of Scientific and Technical Information of China (English)

    LI Yi; WANG Zhong-Jin

    2009-01-01

    The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF) was studied by finite element analysis, which mainly considers the forming process conditions. The whole simulation consisting of three stages, i.e., forming, spring-back and static dent resistance, was carried out continuously using the finite element code ANSYS. The influence of blank holder pressure (BHP) and the drawbead on the stiffness and the static dent resistance of the panels formed using VPF was analyzed. The results show that the adequate setting of the drawbead can increase the plastic deformation of the double-curved panel, which is beneficial to the initial stiffness and the static dent resistance. There is an optimum BHP range for the stiffness and the static dent resistance.

  19. 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.

  20. Rough surface Au@Ag core-shell nanoparticles to fabricating high sensitivity SERS immunochromatographic sensors.

    Science.gov (United States)

    Fu, Qiangqiang; Liu, Hongwu Liu; Wu, Ze; Liu, An; Yao, Cuize; Li, Xiuqing; Xiao, Wei; Yu, Shiting; Luo, Zhi; Tang, Yong

    2015-11-14

    Immunochromatographic sensors (ICSs) are inexpensive, simple, portable, and robust, thus making ICSs commonplace in clinical diagnoses, food testing, and environmental monitoring. However, commonly used gold nanoparticles (AuNPs) ICSs have low sensitivity. Therefore, we developed highly sensitive surface enhanced Raman scattering (SERS) ICSs. To enhance the sensitivity of SERS ICSs, rough surface core-shell Au@Ag nanoparticles (RSAu@AgNPs) were prepared by coating silver on the surface of gold nanoflowers (AuNFs). Then these nanoparticles were used as SERS substrate in the SERS ICSs, after which the SERS ICSs were implemented to detect haemoglobin and heavy metal cadmium ion (Cd(2+)). The limit of detection (LOD) of the SERS ICSs for detecting haemoglobin was 8 ng/mL, and the linear range of the SERS ICSs was from 31.3 to 2000 ng/mL. The LOD of the SERS ICSs for detecting Cd(2+) was 0.05 ng/mL and the linear analysis range was from 0.05 to 25 ng/mL. The cross reactivity of the SERS ICSs was studied and results showed that the SERS ICSs exhibited highly specific for detection of haemoglobin and Cd(2+), respectively. The SERS ICSs were then used to detect haemoglobin (spiked in serum and in stool) and Cd(2+) (spiked in tap water, river water, and soil leaching water), and the results showed high recovery. These characteristics indicated that SERS ICSs were ideal tools for clinical diagnosis and environmental pollution monitoring.

  1. 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.

  2. 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.

  3. Static deformation modeling and analysis of flexure hinges made of a shape memory alloy

    Science.gov (United States)

    Du, Zhijiang; Yang, Miao; Dong, Wei; Zhang, Dan

    2016-11-01

    The flexure hinge is a key element in compliant mechanisms to achieve continuous motion; however the motion range of a flexure hinge is severely restricted by the material’s allowable strain. Due to the superelasticity effect, shape memory alloys (SMAs) can undergo much larger strain than other metals; this means that they are excellent candidates for the fabrication of flexure hinges with a large motion range. In this paper, a simple static deformation modeling approach is proposed for a flexure hinge made of a SMA. The superelastic behavior of the SMA is described by Brinson’s constitutive model. The flexure hinge is considered as a non-prismatic cantilever beam associated with geometrical and material nonlinearities. Govern equations of the flexure hinge are derived and solved numerically by applying the nonlinear bending theory of the Euler-Bernoulli beam. Experimental tests show that the proposed modeling approach can predict the deformation of the flexure hinge precisely; the maximum relative error is less than 6.5%. Based on the static deformation model, the motion capacity, the stiffness characteristic and the rotational error of the flexure hinge are also investigated. The results reveal that the flexure hinge made of a SMA has great potential to construct compliant mechanisms with a large motion range.

  4. Polarization-corrosion behavior of commercial gold- and silver-base casting alloys in Fusayama solution.

    Science.gov (United States)

    Johnson, D L; Rinne, V W; Bleich, L L

    1983-12-01

    Based on polarization measurements, high Au alloys are highly corrosion-resistant and exhibit the lowest corrosion rates; intermediate Au, Ag, and Pd alloys with Cu are passive but exhibit higher corrosion rates. Twenty weight percent (w/o) In-Ag alloys exhibit active corrosion behavior at potentials only 100 mV noble to the corrosion potential.

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

    Science.gov (United States)

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

    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 solution for 24 hours. In Co-Cr and Ti-alloy, Alloy Primer (MDP + VBATDT) and MAC-Bond II (MAC-10) were applied, while Alloy Primer and V-Primer (VBATDT) were applied to Au-Ag-Pd alloys. After surface treatment, veneering composite resin were applied and shear bond strength test were conducted. RESULTS Alloy Primer showed higher shear bond strength than MAC-Bond II in Co-Cr alloys and Au-Ag-Pd alloy (Pveneer resin to Co-Cr and Au-Ag-Pd alloys. PMID:26576256

  6. Observation of a mixed-metal transition in heterobimetallic Au/Ag dicyanide systems.

    Science.gov (United States)

    Hettiarachchi, Samanthika R; Schaefer, Brian K; Yson, Renante L; Staples, Richard J; Herbst-Irmer, Regine; Patterson, Howard H

    2007-08-20

    Crystals of the mixed-metal heterobimetallic Au/Ag dicyanide complex, K[AuxAg1-x(CN)2] (x = 0-->1), were obtained by slow evaporation. The mixed-metal complex K[Au0.44Ag0.56(CN)2] crystallizes in a rhombohedral crystal system, space group R. The crystal structure consists of layers of linear chains of Au(CN)2- and Ag(CN)2- ions and K+ ions that connect the layers through the N atoms. The excitation and emission spectra of single crystals of K[AuxAg1-x(CN)2] were recorded at 4.2-180 K using excitation wavelengths between 230 and 260 nm. Two emission bands due to Ag-Au interactions were observed at 343 and 372 nm. Lifetime measurements indicate the shorter-wavelength emission corresponds to fluorescence and the longer-wavelength band is phosphorescence. These new emission bands are not seen in the pure K[Ag(CN)2] or pure K[Au(CN)2] crystals. Extended Hückel calculations show that the LUMO of the mixed-metal system is bonding while the HOMO is antibonding or very weakly bonding. Moreover, excited-state extended Hückel calculations indicate the formation of exciplexes with shorter metal-metal distances and higher metal-metal overlap populations than the corresponding ground-state oligomers. The luminescence is assigned to a mixed-metal transition from a molecular orbital with Au character to a molecular orbital with Ag character.

  7. 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.

  8. Static and dynamic cyclic oxidation of 12 nickel-, cobalt-, and iron-base high-temperature alloys

    Science.gov (United States)

    Barrett, C. A.; Johnston, J. R.; Sanders, W. A.

    1978-01-01

    Twelve typical high-temperature nickel-, cobalt-, and iron-base alloys were tested by 1 hr cyclic exposures at 1038, 1093, and 1149 C and 0.05 hr exposures at 1093 C. The alloys were tested in both a dynamic burner rig at Mach 0.3 gas flow and in static air furnace for times up to 100 hr. The alloys were evaluated in terms of specific weight loss as a function of time, and X-ray diffraction analysis and metallographic examination of the posttest specimens. A method previously developed was used to estimate specific metal weight loss from the specific weight change of the sample. The alloys were then ranked on this basis. The burner-rig test was more severe than a comparable furnace test and resulted in an increased tendency for oxide spalling due to volatility of Cr in the protective scale and the more drastic cooling due to the air-blast quench of the samples. Increased cycle frequency also increased the tendency to spall for a given test exposure. The behavior of the alloys in both types of tests was related to their composition and their tendency to form scales. The alloys with the best overall behavior formed alpha-Al2O3 aluminate spinels.

  9. Influence of static tensile testing on the deformation behavior of Al-4% Cu alloy containing micro- and nanoparticles

    Science.gov (United States)

    Khrustalyov, Anton; Vorozhtov, Sergey; Kulkov, Sergey

    2016-11-01

    At present, aluminum alloys reinforced with nonmetallic particles are of great interest in various fields of science and technology due to their high specific strength, hardness, wear resistance, and other properties. At the same time there is a great interest in the study of processes occurring during plastic deformation of such materials under static tensile loading. Plastic flow of metals occurs through the creation and movement of linear defects (dislocations), in which there is a phenomenon of discontinuous yielding. An introduction of particles into aluminum alloy promotes a considerable increase of stiffness and specific strength of alloys, and the study of the deformation behavior of such alloys is of great interest. The objective of this research is to analyze mechanical properties and the deformation behavior of aluminum alloy with the identification of mechanisms of plastic deformation when introducing solid nonmetallic micro- and nanoparticles into the soft aluminum matrix. An analysis of the microstructure of the obtained alloys shows that the introduction of particles (Al2O3, TiB2, TiC) leads to a reduction of the alloy grain size from 350 to 170 µm while residual porosity does not exceed 2%. Tensile tests performed show that the change in the type and quantity of particles also changes characteristics of discontinuous yielding, thus resulting in an increase of yield strength (from 18 to 40 MPa), reduction of ductility (from 15 to 2%), and moreover a significant increase of tensile strength (from 77 to 130 MPa), as compared to the initial Al-4 wt % Cu alloy.

  10. A facile strategy to synthesize bimetallic Au/Ag nanocomposite film by layer-by-layer assembly technique

    Science.gov (United States)

    Zhang, Li; Wang, Cong; Zhang, Yi

    2012-05-01

    A facile strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) nanocomposite films by alternating absorption of poly-(ethyleneimine)-silver ions and Au onto substrates and subsequent reduction of the silver ions. The composition, micro-structure and properties of the {PEI-Ag/Au}n nanocomposite films were characterized by ultraviolet visible spectroscopy (UV-vis), transmisson electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), surface enhanced Raman scattering (SERS) and cyclic voltammetry (CV). The UV-vis characteristic absorbances of {PEI-Ag/Au}n nanocomposite thin film increase almost linear with the number of bilayers, which indicates a process of uniform assembling. Appearance of a double plasmon bands in the visible region and the lack of apparent core-shell structures in the TEM images confirm the formation of bimetallic Au-Ag nanoparticles. The result of XPS also demonstrates the existence of Ag and Au nanoparticles in the nanocomposite films. TEM and FESEM images show that these Ag and Au nanoparticles in the films possess sphere structure with the size of 20-25 nm. The resulting {PEI-Ag/Au}n films inherit the properties from both the metal Ag and Au, which exhibits a unique performance in SERS and electrocatalytic activities to the oxidation of dopamine. As a result, the {PEI-Ag/Au}n films are more attractive compared to {PEI-Ag/PSS}n and {PEI/Au}n films.

  11. Localized surface plasmon resonance-based hybrid Au-Ag nanoparticles for detection of Staphylococcus aureus enterotoxin B

    Science.gov (United States)

    Zhu, Shaoli; Du, ChunLei; Fu, Yongqi

    2009-09-01

    A triangular hybrid Au-Ag nanoparticles array was proposed for the purpose of biosensing in this paper. Constructing the hybrid nanoparticles, an Au thin film is capped on the Ag nanoparticles which are attached on glass substrate. The hybrid nanoparticles array was designed by means of finite-difference and time-domain (FDTD) algorithm-based computational numerical calculation and optimization. Sensitivity of refractive index of the hybrid nanoparticles array was obtained by the computational calculation and experimental detection. Moreover, the hybrid nanoparticles array can prevent oxidation of the pure Ag nanoparticles from atmosphere environment because the Au protective layer was deposited on top of the Ag nanoparticles so as to isolate the Ag particles from the atmosphere. We presented a novel surface covalent link method between the localized surface plasmon resonance (LSPR) effect-based biosensors with hybrid nanoparticles array and the detected target molecules. The generated surface plasmon wave from the array carries the biological interaction message into the corresponding spectra. Staphylococcus aureus enterotoxin B (SEB), a small protein toxin was directly detected at nanogramme per milliliter level using the triangular hybrid Au-Ag nanoparticles. Hence one more option for the SEB detection is provided by this way.

  12. STEM-EELS analysis of multipole surface plasmon modes in symmetry-broken AuAg nanowire dimers

    Science.gov (United States)

    Schubert, Ina; Sigle, Wilfried; van Aken, Peter A.; Trautmann, Christina; Toimil-Molares, Maria Eugenia

    2015-03-01

    Surface plasmon coupling in nanowires separated by small gaps generates high field enhancements at the position of the gap and is thus of great interest for sensing applications. It is known that the nanowire dimensions and in particular the symmetry of the structures has strong influence on the plasmonic properties of the dimer structure. Here, we report on multipole surface plasmon coupling in symmetry-broken AuAg nanowire dimers. Our dimers, consisting of two nanowires with different lengths and separated by gaps of only 10 to 30 nm, were synthesized by pulsed electrochemical deposition in ion track-etched polymer templates. Electron energy-loss spectroscopy in scanning transmission electron microscopy allows us to resolve up to nine multipole order surface plasmon modes of these dimers spectrally separated from each other. The spectra evidence plasmon coupling between resonances of different multipole order, resulting in the generation of additional plasmonic modes. Since such complex structures require elaborated synthesis techniques, dimer structures with complex composition, morphology and shape are created. We demonstrate that finite element simulations on pure Au dimers can predict the generated resonances in the fabricated structures. The excellent agreement of our experiment on AuAg dimers with finite integration simulations using CST microwave studio manifests great potential to design complex structures for sensing applications.

  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. Structural and mechanical properties of 7075 alloy strips fabricated by roll-casting in a static magnetic field

    Science.gov (United States)

    Su, Xin; Xu, Guang-ming; Jiang, Jiu-wen

    2014-07-01

    The influences of a 0.2 T static magnetic field on the microstructure of 7075 aluminum alloys sheets produced with a twin-roll continuous caster at 675°C were investigated in this paper. Under a uniform magnetic field, the primary dendrites were refined and tended to be equiaxed. The microstructure consisted of an intermediate case between dendritic and equiaxed grains. Moreover, the use of an external static field in the twin-roll casting process can reduce heat discharge, resulting in a decrease in undercooling, and may also account for the abatement of segregation bands. In addition, the static magnetic field effectively improved the solute mixing capacity, and the added atoms more easily diffused from precipitates to the α-Al matrix, which resulted in an increase in the mechanical properties of the rolled sheets. Specimens prepared both in the presence of a static magnetic field and in the absence of a static magnetic field exhibited brittle-fracture characteristics.

  15. Structural and mechanical properties of 7075 alloy strips fabricated by roll-casting in a static magnetic field

    Institute of Scientific and Technical Information of China (English)

    Xin Su; Guang-ming Xu; Jiu-wen Jiang

    2014-01-01

    The influences of a 0.2 T static magnetic field on the microstructure of 7075 aluminum alloys sheets produced with a twin-roll continuous caster at 675°C were investigated in this paper. Under a uniform magnetic field, the primary dendrites were refined and tended to be equiaxed. The microstructure consisted of an intermediate case between dendritic and equiaxed grains. Moreover, the use of an external static field in the twin-roll casting process can reduce heat discharge, resulting in a decrease in undercooling, and may also account for the abatement of segregation bands. In addition, the static magnetic field effectively improved the solute mixing capacity, and the added atoms more easily diffused from precipitates to theα-Al matrix, which resulted in an increase in the mechanical properties of the rolled sheets. Specimens prepared both in the presence of a static magnetic field and in the absence of a static magnetic field exhibited brittle-fracture characteristics.

  16. 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

  17. Microwave-assisted synthesis of photoluminescent glutathione-capped Au/Ag nanoclusters: A unique sensor-on-a-nanoparticle for metal ions, anions, and small molecules

    Institute of Scientific and Technical Information of China (English)

    Jia Zhang[1; Yue Yuan[1; Yu Wang[2; Fanfei Sun[2; Gaolin Liang[1; Zheng Jiang[2; Shu-Hong Yu[1,3

    2015-01-01

    Even though great advances have been achieved in the synthesis of luminescent metal nanoclusters, it is still challenging to develop metal nanoclusters with high quantum efficiency as well as multiple sensing functionalities. Here, we demonstrate the rapid preparation of glutathione-capped Au/Ag nanoclusters (GS-Au/Ag NCs) using microwave irradiation and their unique sensing capacities. Compared to bare GS-Au NCs, the doped Au/Ag NCs possess an enhanced quantum yield (7.8% compared to 2.2% for GS-Au NCs). Several characterization techniques were used to elucidate the atomic composition, particulate character, and electronic structure of the fabricated NCs. According to the X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectra, a significant amount of Au exists in the oxidized state as Au(I), and the Ag atoms are positively charged. In contrast to those nanoclusters that detect only one analyte, the GS-Au/Ag NCs can be used as a versatile sensor for metal ions, anions, and small molecules. In this manner, the NCs can be regarded as a unique sensor-on-a-nanoparticle.

  18. Surface plasmon dispersion engineering via double-metallic AU/AG layers for nitride light-emitting diodes

    Science.gov (United States)

    Tansu, Nelson; Zhao, Hongping; Zhang, Jing; Liu, Guangyu

    2014-04-01

    A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.

  19. Interaction of Au, Ag, and Bi ions with Ba2YCu3O(7-y) - Implications for superconductor applications

    Science.gov (United States)

    Hepp, A. F.; Gaier, J. R.; Pouch, J. J.; Hambourger, P. D.

    1988-01-01

    Results are presented on the reactions of Au, Ag, and Bi ions with Ba2YCu3O(7-y) oxides and on the properties of the resultant materials. The results indicate that Au(3+) structural chemistry makes gold an excellent candidate for multiphase structures of the Ba2Y(Cu/1-x/Au/x/)3O(7-y)-type substituted superconductors. Silver is structurally and chemically compatible with the perovskite structure, but when it forms a second phase, it does so without the destruction of the superconducting phase, making silver a useful metal for metal/ceramic applications. On the other hand, bismuth was shown to degrade Tc phase or to form other phases, indicating that it may not be useful in applications with rare-earth-based superconductors.

  20. A facile strategy to synthesize bimetallic Au/Ag nanocomposite film by layer-by-layer assembly technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Li, E-mail: zhlisuzh@163.com [Anhui Key Laboratory of Spin Electron and Nanomaterials (Cultivating Base), Suzhou University, Suzhou 234000 (China); Wang Cong; Zhang Yi [Anhui Key Laboratory of Spin Electron and Nanomaterials (Cultivating Base), Suzhou University, Suzhou 234000 (China)

    2012-05-01

    A facile strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) nanocomposite films by alternating absorption of poly-(ethyleneimine)-silver ions and Au onto substrates and subsequent reduction of the silver ions. The composition, micro-structure and properties of the {l_brace}PEI-Ag/Au{r_brace}{sub n} nanocomposite films were characterized by ultraviolet visible spectroscopy (UV-vis), transmisson electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), surface enhanced Raman scattering (SERS) and cyclic voltammetry (CV). The UV-vis characteristic absorbances of {l_brace}PEI-Ag/Au{r_brace}{sub n} nanocomposite thin film increase almost linear with the number of bilayers, which indicates a process of uniform assembling. Appearance of a double plasmon bands in the visible region and the lack of apparent core-shell structures in the TEM images confirm the formation of bimetallic Au-Ag nanoparticles. The result of XPS also demonstrates the existence of Ag and Au nanoparticles in the nanocomposite films. TEM and FESEM images show that these Ag and Au nanoparticles in the films possess sphere structure with the size of 20-25 nm. The resulting {l_brace}PEI-Ag/Au{r_brace}{sub n} films inherit the properties from both the metal Ag and Au, which exhibits a unique performance in SERS and electrocatalytic activities to the oxidation of dopamine. As a result, the {l_brace}PEI-Ag/Au{r_brace}{sub n} films are more attractive compared to {l_brace}PEI-Ag/PSS{r_brace}{sub n} and {l_brace}PEI/Au{r_brace}{sub n} films.

  1. 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.

  2. Preparation and Characterization of Bimetal Core-Shell Structure Supported Au@Ag/TiO_2 Catalyst%双金属核壳结构负载型Au@Ag/TiO_2催化剂的制备及表征

    Institute of Scientific and Technical Information of China (English)

    孙彦红; 张敏; 杨建军

    2009-01-01

    利用溶胶法制备了Au核Ag壳(Au@Ag)结构复合纳米粒子,用粉末-溶胶法和水热合成法使其负载于TiO_2纳米粒子上,利用紫外-可见吸收光谱、X射线粉末衍射、透射电子显微镜对复合结构材料进行了结构表征,并对其光催化消除臭氧的性能进行了研究.结果表明,制备方法、Au/Ag化学计量比及金属负载量等对光催化消除臭氧的活性均有很大影响.采用粉末-溶胶法制备的1%-Au@Ag/TiO_2(n_Au/n_Ag=1∶3)催化剂,由于TiO_2表面沉积的Au@Ag金属颗粒尺寸小且分散度高,而且1%的金属担载量有利于光生电子空穴的有效分离,光催化消除臭氧的活性最高.%Core-shell Au@Ag nanoparticles were prepared by the sol method and deposited on TiO_2 nanoparticles by the powder-sol method and the hydrothennal method. The structure of sol and Au@Ag/TiO_2 was characterized by UV-Vis, XRD, and TEM techniques. The activity of phtocatalytic elimination of ozone was investigated on Au@Ag/TiO_2surface. The results show that preparation method, Au/Ag stoichiometric proportion and the metal loading have great effect on the activity of photocatalytic elimination of ozone, 1% Au@Ag/TiO_2(n_Au/n_Ag=1:3) photocatalyst prepared by powder-sol method has the best activity for photocatalytic elimination of ozone due to the small particle size of Au@Ag, higher dispersion of metal and the effective separation of the photo-generated electron and hole.

  3. Quasi-static Torsional Deformation Behavior of Porous Ti6Al4V alloy.

    Science.gov (United States)

    Balla, Vamsi Krishna; Martinez, Shantel; Rogoza, Ben Tunberg; Livingston, Chase; Venkateswaran, Deepak; Bose, Susmita; Bandyopadhyay, Amit

    2011-07-20

    Laser processed Ti6Al4V alloy samples with total porosities of 0%, 10% and 20% have been subjected to torsional loading to determine mechanical properties and to understand the deformation behavior. The torsional yield strength and modulus of porous Ti alloy samples was found to be in the range of 185-332 MPa and 5.7-11 GPa, respectively. With an increase in the porosity both the strength and the modulus decreased, and at 20% porosity the torsional modulus of Ti6Al4V alloy was found to be very close to that of human cortical bone. Further, the experiments revealed clear strain hardening and ductile deformation in all the samples, which suggests that the inherent brittleness associated solid-state sintered porous materials can be completely eliminated via laser processing for load bearing metal implant applications.

  4. Shape memory alloy actuation effect on subsonic static aeroelastic deformation of composite cantilever plate

    Science.gov (United States)

    Hussein, A. M. H.; Majid, D. L. Abdul; Abdullah, E. J.

    2016-10-01

    Shape memory alloy (SMA) is one of the smart materials that have unique properties and used recently in several aerospace applications. SMAs are metallic alloys that can recover permanent strains when they are heated above a certain temperature. In this study, the effects of SMA actuation on the composite plate under subsonic aeroelastic conditions are examined. The wind tunnel test is carried out for two configurations of a cantilever shape memory alloy composite plate with a single SMA wire fixed eccentrically. Strain gage data for both bending and torsional strain are recorded and demonstrated during the aeroelastic test for active and non-active SMA wire in two locations. The cyclic actuation of the SMA wire embedded inside the composite plate is also investigated during the aeroelastic test. The results show reduction in both bending and torsional strain of the composite plate after activation of the SMA wire during the wind tunnel test.

  5. Welding Distortion Control of Thin A1 Alloy Plate by Static Thermal Tensioning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mechanism and effectiveness of welding distortion mitigation by static thermal tensioning were investigated by both finite element analysis and experiments. It shows that preset thermal tensioning can reduce longitudinal plastic compression remained in the weld and its adjacent zone significantly, so decrease the longitudinal residual stress and the susceptibility to welding distortion.

  6. Alkaline sulfide pretreatment of an antimonial refractory Au-Ag ore for improved cyanidation

    Science.gov (United States)

    Alp, Ibrahim; Celep, Oktay; Deveci, Haci

    2010-11-01

    This paper presents the alkaline sulfide pretreatment of an antimonial refractory gold and silver ore. In the ore, gold occurs mainly as gold-silver alloys and as associated with quartz and framboidal pyrite grains, and, to a small extent, as the inclusions within antimonial sulfides. Silver is present extensively as antimonial sulfides such as andorite. Alkaline sulfide pretreatment was shown to allow the decomposition of the antimonial sulfide minerals (up to 98% Sb removal) and to remarkably improve the amenability of gold (e.g., from silver (e.g., from leaching. An increase in reagent concentration (1-4 mol/L Na2S or NaOH) and temperature (20-80°C), and a decrease in particle size seem to produce an enhancing effect on metal extraction. These findings suggest that alkaline sulfide leaching can be suitably used as a chemical pretreatment method prior to the conventional cyanidation for antimonial refractory gold and silver ores.

  7. Design and Cellular Fate of Bioinspired Au-Ag Nanoshells@Hybrid Silica Nanoparticles.

    Science.gov (United States)

    Soulé, Samantha; Bulteau, Anne-Laure; Faucher, Stéphane; Haye, Bernard; Aimé, Carole; Allouche, Joachim; Dupin, Jean-Charles; Lespes, Gaëtane; Coradin, Thibaud; Martinez, Hervé

    2016-10-04

    Silica-coated gold-silver alloy nanoshells were obtained via a bioinspired approach using gelatin and poly-l-lysine (PLL) as biotemplates for the interfacial condensation of sodium silicate solutions. X-ray photoelectron spectroscopy was used as an efficient tool for the in-depth and complete characterization of the chemical features of nanoparticles during the whole synthetic process. Cytotoxicity assays using HaCaT cells evidenced the detrimental effect of the gelatin nanocoating and significant induction of late apoptosis after silicification. In contrast, PLL-modified nanoparticles had less biological impact that was further improved by the silica layer, and uptake rates of up to 50% of those of the initial particles could be achieved. These results are discussed considering the effect of nanosurface confinement of the biopolymers on their chemical and biological reactivity.

  8. Static Softening in a Ni-30Fe Austenitic Model Alloy After Hot Deformation: Microstructure and Texture Evolution

    Science.gov (United States)

    Beladi, Hossein; Cizek, Pavel; Taylor, Adam S.; Rohrer, Gregory S.; Hodgson, Peter D.

    2017-02-01

    In the current study, the microstructure and texture characteristics of a model Ni-30Fe austenitic alloy were investigated during hot deformation and subsequent isothermal holding. The deformation led to the formation of self-screening arrays of microbands within a majority of grains. The microbands characteristics underwent rather modest changes during the post-deformation annealing, which suggests that limited dislocation annihilation occurs within the corresponding dislocation walls. The fraction of statically recrystallized (SRX) grains progressively increased with the holding time and closely matched the softening fraction measured from the offset flow stress approach. The corresponding texture was weak and preserved its character with the holding time. There was no pronounced temperature effect on the grain boundary character distribution after the completion of SRX. The Σ3 and Σ9 coincidence site lattice boundaries were characterized as (111) pure twist and (1-14) symmetric tilt types, respectively. Nonetheless, the recrystallization temperature slightly affected the grain boundary network.

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

    Science.gov (United States)

    Xiu, Fu-Rong; Qi, Yingying; Zhang, Fu-Shen

    2015-07-01

    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 60min for Au and Pd, and 410°C and 30min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO+HL)-treated PCBs with iodine-iodide system were leaching time of 120min (90min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10g/mL (1:8g/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.

  10. Phonons, nature of bonding, and their relation to anomalous thermal expansion behavior of M2O (M = Au, Ag, Cu)

    Science.gov (United States)

    Gupta, M. K.; Mittal, R.; Chaplot, S. L.; Rols, S.

    2014-03-01

    We report a comparative study of the dynamics of Cu2O, Ag2O, and Au2O (i.e., M2O with M = Au, Ag, and Cu) using first principle calculations based on the density functional theory. Here, for the first time, we show that the nature of chemical bonding and open space in the unit cell are directly related to the magnitude of thermal expansion coefficient. A good match between the calculated phonon density of states and that derived from inelastic neutron scattering measurements is obtained for Cu2O and Ag2O. The calculated thermal expansions of Ag2O and Cu2O are negative, in agreement with available experimental data, while it is found to be positive for Au2O. We identify the low energy phonon modes responsible for this anomalous thermal expansion. We further calculate the charge density in the three compounds and find that the magnitude of the ionic character of the Ag2O, Cu2O, and Au2O crystals is in decreasing order, with an Au-O bond of covalent nature strongly rigidifying the Au4O tetrahedral units. The nature of the chemical bonding is also found to be an important ingredient to understand the large shift of the phonon frequencies of these solids with pressure and temperature. In particular, the quartic component of the anharmonic term in the crystal potential is able to account for the temperature dependence of the phonon modes.

  11. Induced polarization imaging applied to exploration for low-sulfidation epithermal Au-Ag deposits, Seongsan mineralized district, South Korea

    Science.gov (United States)

    Han, Man-Ho; Shin, Seung Wook; Park, Samgyu; Cho, Seong-Jun; Kim, Jung-Ho

    2016-10-01

    The determination of mineralization boundaries during mineral exploration for undiscovered low-sulfidation epithermal Au-Ag deposits is a significant challenge because of the extensive survey areas required. Induced polarization (IP) imaging is an effective geophysical technique for the detection of sulfides or clay. Thus, this method is considered useful to determine the boundaries of subsurface mineralization and hydrothermal alteration associated with epithermal deposits. We used 2D and 3D IP imaging to define the silicification and mineralization boundaries of the Moisan deposit in the Seongsan mineralized district, which is geologically well-known. The boundaries of the silicification zone were defined by high resistivity values of 600 Ω-m, and those of the mineralization zone were defined by high global chargeability values of 3 mV V-1. The continuity of the high resistivity anomaly corresponded well to the silicification (quartz veins) exposed in outcrop. In addition, it is geologically reasonable that the chargeability anomaly, ⩾3 mV V-1, associated with the mineralization/hydrothermal alteration zone was concentrated at near-surface depths, and extensively surrounding the resistivity anomaly, ⩾600 Ω-m, associated with the silicification zone.

  12. High-performance ambipolar self-assembled Au/Ag nanowire based vertical quantum dot field effect transistor

    Science.gov (United States)

    Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Wang, Jianlong; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

    2016-10-01

    Most lateral PbSe quantum dot field effect transistors (QD FETs) show a low on current/off current (I on/I off) ratio in charge transport measurements. A new strategy to provide generally better performance is to design PbSe QD FETs with vertical architecture, in which the structure parameters can be tuned flexibly. Here, we fabricated a novel room-temperature operated vertical quantum dot field effect transistor with a channel of 580 nm, where self-assembled Au/Ag nanowires served as source transparent electrodes and PbSe quantum dots as active channels. Through investigating the electrical characterization, the ambipolar device exhibited excellent characteristics with a high I on/I off current ratio of about 1 × 105 and a low sub-threshold slope (0.26 V/decade) in the p-type regime. The all-solution processing vertical architecture provides a convenient way for low cost, large-area integration of the device.

  13. The Effect of Short Duration Electric Current on the Quasi-Static Tensile Behavior of Magnesium AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Trung Thien Nguyen

    2016-01-01

    Full Text Available The effect of a single pulse of electric current with short duration on the quasi-static tensile behavior of a magnesium AZ31 alloy is experimentally investigated. A single pulse of electric current with duration less than 1 second is applied to the specimen, while the specimen is being deformed in the plastic region under quasi-static tensile loads. After a nearly instant decrease of flow stress at the pulse of electric current, the flow stress shows strain hardening until the failure of the specimen. The experimental result shows that the strain-hardening parameters (the strength coefficient and the strain-hardening exponent of the hardening curve after the electric current strongly depend on the applied electric energy density (electric energy per unit volume. Empirical expressions are suggested to describe the hardening behavior after the pulse as a function of the electric energy density and are compared with the empirical expressions suggested for advanced high-strength steels.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, Brahmananda, E-mail: santra@iitg.ernet.in; Sarma, S., E-mail: santra@iitg.ernet.in; Srinivasan, A., E-mail: santra@iitg.ernet.in; Santra, S. B., E-mail: santra@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039 (India)

    2014-04-24

    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 Co{sub 45}Ni{sub 25}Ga{sub 30} 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 T{sub C} (∼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.

  15. Au-Ag-Au double shell nanoparticles-based localized surface plasmon resonance and surface-enhanced Raman scattering biosensor for sensitive detection of 2-mercapto-1-methylimidazole.

    Science.gov (United States)

    Liao, Xue; Chen, Yanhua; Qin, Meihong; Chen, Yang; Yang, Lei; Zhang, Hanqi; Tian, Yuan

    2013-12-15

    In this paper, Au-Ag-Au double shell nanoparticles were prepared based on the reduction of the metal salts HAuCl4 and AgNO3 at the surface of seed particles. Due to the synergistic effect between Au and Ag, the hybrid nanoparticles are particularly stable and show excellent performances on the detection of 2-mercapto-1-methylimidazole (methimazole). The binding of target molecule at the surface of Au-Ag-Au double shell nanoparticles was demonstrated based on both localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS) spectra. The LSPR intensity is directly proportional to the methimazole concentration in the range of 0.10-3.00×10(-7) mol L(-1). The SERS spectrum can be applied in identification of methimazole molecule. The LSPR coupled with SERS based on the Au-Ag-Au double shell nanoparticles would be very attractive for the quantitative determination and qualitative analysis of the analytes in medicines.

  16. 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.

  17. 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.

  18. Synthesis of bimetallic gold-silver alloy nanoclusters by simple mortar grinding.

    Science.gov (United States)

    Murugadoss, Arumugam; Kai, Noriko; Sakurai, Hidehiro

    2012-02-21

    A macroscale quantity of bimetallic Au-Ag alloy nanoclusters was achieved through sequential reduction by simple mortar grinding. The chitosan biopolymer was used as both a stabilizing and reducing agent. These nanoclusters exhibit excellent catalytic activity toward the reduction of 4-nitrophenol.

  19. Tuning the structural and optical properties of gold/silver nano-alloys prepared by laser ablation in liquids for optical limiting, ultra-sensitive spectroscopy, and optical trapping

    Science.gov (United States)

    Messina, E.; D'Urso, L.; Fazio, E.; Satriano, C.; Donato, M. G.; D'Andrea, C.; Maragò, O. M.; Gucciardi, P. G.; Compagnini, G.; Neri, F.

    2012-12-01

    The plasmon resonance of metallic Au/Ag nano-alloys in the colloidal state was tuned from 400 nm to 500 nm using a laser irradiated technique performed directly in the liquid state. Interesting optical nonlinearities, trapping effects and spectroscopic enhancements were detected by modifying the gold molar fraction in the nano-alloys. In particular a reduction of the limiting threshold was observed by increasing the gold amount. The SERS activity of the Au/Ag alloys was tested in liquid and in solid state in presence of linear carbon chains as probe molecules. The increased Raman signals for nanoparticles with different Au/Ag atomic ratio are presented. Finally, studies and prospects for optical and Raman tweezers experiments are discussed.

  20. Numerical analysis of static performance comparison of friction stir welded versus riveted 2024-T3 aluminum alloy stiffened panels

    Science.gov (United States)

    Shao, Qing; He, Yuting; Zhang, Teng; Wu, Liming

    2014-07-01

    Most researches on the static performance of stiffened panel joined by friction stir welding(FSW) mainly focus on the compression stability rather than shear stability. To evaluate the potential of FSW as a replacement for traditional rivet fastening for stiffened panel assembly in aviation application, finite element method(FEM) is applied to compare compression and shear stability performances of FSW stiffened panels with stability performances of riveted stiffened panels. FEMs of 2024-T3 aluminum alloy FSW and riveted stiffened panels are developed and nonlinear static analysis method is applied to obtain buckling pattern, buckling load and load carrying capability of each panel model. The accuracy of each FEM of FSW stiffened panel is evaluated by stability experiment of FSW stiffened panel specimens with identical geometry and boundary condition and the accuracy of each FEM of riveted stiffened panel is evaluated by semi-empirical calculation formulas. It is found that FEMs without considering weld-induced initial imperfections notably overestimate the static strengths of FSW stiffened panels. FEM results show that, buckling patterns of both FSW and riveted compression stiffened panels represent local buckling of plate between stiffeners. The initial buckling waves of FSW stiffened panel emerge uniformly in each plate between stiffeners while those of riveted panel mainly emerge in the mid-plate. Buckling patterns of both FSW and riveted shear stiffened panels represent local buckling of plate close to the loading corner. FEM results indicate that, shear buckling of FSW stiffened panel is less sensitive to the initial imperfections than compression buckling. Load carrying capability of FSW stiffened panel is less sensitive to the initial imperfections than initial buckling. It can be concluded that buckling loads of FSW panels are a bit lower than those of riveted panels whereas carrying capabilities of FSW panels are almost equivalent to those of riveted

  1. First-principles calculation of the effects of partial alloy disorder on the static and dynamic magnetic properties of Co2MnSi

    Science.gov (United States)

    Pradines, B.; Arras, R.; Abdallah, I.; Biziere, N.; Calmels, L.

    2017-03-01

    On the basis of fully relativistic Korringa-Kohn-Rostoker calculations and in conjunction with the coherent potential approximation and the linear response formalism, we present a complete ab initio study of the influence of alloy disorder on the static and dynamic (Gilbert damping) magnetic properties and on the electronic structure of the half-metallic full-Heusler alloy Co2MnSi . We discuss in particular partial atomic disorders intermediate between the main crystal phases L21 , B2, A2, and D03 of this alloy. We compare our results with homemade experiments and measurements from the literature, and conclude that the presence of a partial D03 -like disorder could explain the relatively high value of the Gilbert damping parameter and the lack of half-metallicity measured in real samples, in which alloy disorder cannot be totally avoided.

  2. 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.

  3. 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

    2016-02-01

    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.

  4. [The study of dimethoate by means of vibrational and surface enhanced Raman spectroscopy on Au/Ag core-shell nanoparticles].

    Science.gov (United States)

    He, Qiang; Li, Si; Yu, Dan-Ni; Zhou, Gunag-Ming; Ji, Fang-Ying; Subklew, Guenter

    2010-12-01

    The vibrational structure of dimethoate, with its solid state and saturated solutions at acidic and basic conditions, was characterized with combination of means of FTIR and FT-Raman vibrational spectroscopy technology, and the comprehensive information about the dimethoate molecular groups' vibrational features was obtained. The surface enhanced Raman scattering (SERS) spectra of dimethoate at different concentrations with different acidic and basic conditions, and adsorbed on the substrate's surface of the core-shell Au/Ag nanoparticles, were also obtained. The adsorption states of dimethoate's molecule on the substrate's surface of the core-shell Au/Ag nanoparticles and the effects by the different acid-base conditions were investigated, with speculation of the adsorption mechanism. From the results, v(as)(NH), v(as)(CH3), v(O=C-N), tau(O=C-N), v(P-O), v(P=S), v(C-C) and delta(P-O-C) are the characteristic peaks of inner dimethoate structure's vibrations; and the concentration range in which dimethoate could interact with core-shell Au/Ag nanoparticles fully is about 1.0 x 10(-3) mol * L(-1) both in acidic and basic conditions. Dimethoate's molecule interacts with SERS' substrate surface mainly through P-O-C, O=C-C, (S-CH2), P=S, and CH3 structures; and the effects of dimethoate's hydrolysis path in acidic and basic conditions on the adsorption are discussed, which give some good references for the research of organophosphorus pesticides' transformations in different environmental systems.

  5. Determining the Concentration Dependent Transformations of Ag Nanoparticles in Complex Media: Using SP-ICP-MS and Au@Ag Core-Shell Nanoparticles as Tracers.

    Science.gov (United States)

    Merrifield, Ruth C; Stephan, Chady; Lead, Jamie

    2017-03-01

    The fate, behavior, and impact of engineered nanoparticles (NPs) in toxicological and environmental media are driven by complex processes which are difficult to quantify. A key limitation is the ability to perform measurements at low and environmentally relevant concentrations, since concentration may be a key factor determining fate and effects. Here, we use single particle inductively coupled mass spectroscopy (SP-ICP-MS) to measure directly NP diameter and particle number concentration of suspensions containing gold-silver core-shell (Au@Ag) NPs in EPA moderately hard water (MHW) and MHW containing 2.5 mg L(-1) Suwannee River fulvic acid. The Au core of the Au@Ag NPs acts as an internal standard, and aids in the analysis of the complex Ag transformations. The high sensitivity of SP-ICP-MS, along with the Au@Ag NPs, enabled us to track the NP transformations in the range 0.01 and 50 μg L(-1), without further sample preparation. On the basis of the analysis of both Au and Ag parameters (size, size distribution, and particle number), concentration was shown to be a key factor in NP behavior. At higher concentration, NPs were in an aggregation-dominated regime, while at the lower and environmentally representative concentrations, dissolution of Ag was dominant and aggregation was negligible. In addition, further formation of ionic silver as Ag NPs in the form of AgS or AgCl was shown to occur. Between 1 and 10 μg L(-1), both aggregation and dissolution were important. The results suggest that, under realistic conditions, the role of NP homoaggregation may be minimal. In addition, the complexity of exposure and dose in dose-response relationships is highlighted.

  6. High precision analysis modeling by backward elimination with attitude on interaction effects on Au (Ag)-polymetallic mineralization of Glojeh, Iran

    Science.gov (United States)

    Darabi-Golestan, F.; Hezarkhani, A.

    2016-12-01

    Identification of possible relationship between the elements, in mineralization and geochemical modeling is very important. The Full Cubic Model (FCM) with 90 Predictors including the main effects, quadratic terms, and interaction effects of Ag, As, Cu, Hg, Mn, Nb, P, Pb, Sn, Sr, Zn and U elements was used to create an Optimal and Reduced Cubic Model (ORCM) at vein-style Au (Ag)-polymetallic mineralization of Glojeh. It was generated with multiple regression and variance analysis and enhanced by Backward Elimination Procedure (BEP) for insignificant predictors through 15 steps. All the predictors contributed in ORCM by lowest p-value of 0.07 at degree of freedom (DF) equaled to 36. F ratio and R2 (pred.) criteria showed increasing trend from 0% to 77.80% and 6.12-262.51, respectively in model optimization. The main and interacted elements at ORCM are Sn, U, Pb, Cu and Ag × Sn, As × Mn, As × Zn, Hg × P, P × Sn, Sn2, P2, respectively based on related t-values. Interaction occurred when a pair of elements produces no similar trend on the response at different levels (associated to populations) of another element. Therefore, interaction of two elements on Au concentration was considered, simultaneously. By investigation, a disordinal interaction effect occurs on deposit for Au-As-Mn, Au-Ag-As and Au-Hg-Mn when the third element changes across the background level to vein values. Whereas, ordinal effects was observed at both population for Au-Ag-Hg and Au-As-Hg, since the lines were parallel. It implies that As has similar trend on Au for each value of Hg. The Au-Ag line explains the general downward shift by increasing Hg concentrations from vein to background. It revealed that Hg is more concentrated in background area. The accuracy and precision of this approach have been studied extensively for sample analysis, parameter identification, and modeling to ensure about BEP.

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

    Science.gov (United States)

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

    2014-10-01

    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 stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm2. The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor.

  8. N2-Ar-He systematics and source of ore-forming fluid in Changkeng Au-Ag deposit, central Guangdong, China

    Institute of Scientific and Technical Information of China (English)

    孙晓明; 孙凯; 陈炳辉; 陈敬德; David; I.Norman

    1999-01-01

    Changkeng Au-Ag deposit is a newly-discovered new type precious metal deposit. N2-Ar-He systematics studies and 3He/4He and δD-δ18O composition analyses show that the ore-forming fluid of the deposit is composed mainly of formation water (sedimentary brine) but not of meteoric water, which was thought to be source of the ore-forming fluid by most previous researchers. The content of mantle-derived magmatic water in the ore-forming fluid is quite low, usually lower than 10%. According to the source of the ore-forming fluid, the Changkeng Au-Ag deposit should belong to sedimentary brine transformed deposits. From the Late Jurassic to the Early Cretaceous Period, with deposition and accumulation of thick sediments in Sanzhou Basin, the formation water in the sedimentary layers was expelled from the basin because of overburden pressure and increasing temperature. The expelled fluid moved laterally along sedimentary layers to the margin of the basin, and finally moved upward along a gently-dipping in

  9. Fabrication of Au-Ag nanocage@NaYF4@NaYF4:Yb,Er Core-Shell Hybrid and its Tunable Upconversion Enhancement

    Science.gov (United States)

    Chen, Xu; Zhou, Donglei; Xu, Wen; Zhu, Jinyang; Pan, Gencai; Yin, Ze; Wang, He; Zhu, Yongsheng; Shaobo, Cui; Song, Hongwei

    2017-01-01

    Localized electric filed enhancement by surface plasmon resonance (SPR) of noble metal nanoparticles is an effective method to amplify the upconversion luminescence (UCL) strength of upconversion nanoparticles (UCNPs), whereas the highly effective UCL enhancement of UCNPs in colloids has not been realized until now. Here, we designed and fabricated the colloidal Au-Ag nanocage@NaYF4@NaYF4:Yb,Er core-shell hybrid with different intermediate thickness (NaYF4) and tunable SPR peaks from visible wavelength region to NIR region. After the optimization of the intermediate spacer thickness (~7.5 nm) of NaYF4 NPs and the SPR peak (~950 nm) of noble metal nanoparticles, an optimum enhancement as high as ~25 folds was obtained. Systematic investigation indicates that UCL enhancement mainly originates from the influence of the intermediate spacer and the coupling of Au-Ag nanocages with the excitation electromagnetic field of the UCNPs. Our findings may provide a new thinking on designing highly effective metal@UCNPs core-shell hybrid in colloids.

  10. Fabrication of Au-Ag nanocage@NaYF4@NaYF4:Yb,Er Core-Shell Hybrid and its Tunable Upconversion Enhancement

    Science.gov (United States)

    Chen, Xu; Zhou, Donglei; Xu, Wen; Zhu, Jinyang; Pan, Gencai; Yin, Ze; Wang, He; Zhu, Yongsheng; Shaobo, Cui; Song, Hongwei

    2017-01-01

    Localized electric filed enhancement by surface plasmon resonance (SPR) of noble metal nanoparticles is an effective method to amplify the upconversion luminescence (UCL) strength of upconversion nanoparticles (UCNPs), whereas the highly effective UCL enhancement of UCNPs in colloids has not been realized until now. Here, we designed and fabricated the colloidal Au-Ag nanocage@NaYF4@NaYF4:Yb,Er core-shell hybrid with different intermediate thickness (NaYF4) and tunable SPR peaks from visible wavelength region to NIR region. After the optimization of the intermediate spacer thickness (~7.5 nm) of NaYF4 NPs and the SPR peak (~950 nm) of noble metal nanoparticles, an optimum enhancement as high as ~25 folds was obtained. Systematic investigation indicates that UCL enhancement mainly originates from the influence of the intermediate spacer and the coupling of Au-Ag nanocages with the excitation electromagnetic field of the UCNPs. Our findings may provide a new thinking on designing highly effective metal@UCNPs core-shell hybrid in colloids. PMID:28106128

  11. Bio-mimetic nanostructure self-assembled from Au@Ag heterogeneous nanorods and phage fusion proteins for targeted tumor optical detection and photothermal therapy.

    Science.gov (United States)

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

    2014-10-28

    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 stability, cost-effectivity, biocompatibility and tunable NIR absorption. The fusion proteins were isolated from phage DDAGNRQP specifically selected from f8/8 landscape phage library against colorectal cancer cells in a high-throughput way. Considering the definite charge distribution and low molecular weight, phage fusion proteins were assembled on the negatively charged NR core by electrostatic interactions, exposing the N-terminus fused with DDAGNRQP peptide on the surface. The fluorescent images showed that assembled phage fusion proteins can direct the nanostructure into cancer cells. The nanostructure was more efficient than gold nanorods and silver nanotriangle-based photothermal agents and was capable of specifically ablating SW620 cells after 10 min illumination with an 808 nm laser in the light intensity of 4 W/cm(2). The prepared nanostructure would become an ideal reagent for simutaneously targeted optical imaging and PTT of tumor.

  12. 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.

  13. Dopant-induced 2D-3D transition in small Au-containing clusters: DFT-global optimisation of 8-atom Au-Ag nanoalloys.

    Science.gov (United States)

    Heiles, Sven; Logsdail, Andrew J; Schäfer, Rolf; Johnston, Roy L

    2012-02-21

    A genetic algorithm (GA) coupled with density functional theory (DFT) calculations is used to perform global optimisations for all compositions of 8-atom Au-Ag bimetallic clusters. The performance of this novel GA-DFT approach for bimetallic nanoparticles is tested for structures reported in the literature. New global minimum structures for various compositions are predicted and the 2D-3D transition is located. Results are explained with the aid of an analysis of the electronic density of states. The chemical ordering of the predicted lowest energy isomers are explained via a detailed analysis of the charge separation and mixing energies of the bimetallic clusters. Finally, dielectric properties are computed and the composition and dimensionality dependence of the electronic polarizability and dipole moment is discussed, enabling predictions to be made for future electric beam deflection experiments.

  14. DISLOCATIONS MOBILITY UNDER THE IMAGE FORCE EFFECT IN BICRYSTALS OF CFC MATERIALS: CU-X, X = PB, AL, AU, AG AND NI

    Directory of Open Access Journals (Sweden)

    A OUCHTATI

    2015-06-01

    Full Text Available The image force undergone by a matrix dislocations close and parallel to an interphase boundary is studied in Cu-X bicrystals (with X = Pb, Al, Au, Ag, Ni for disorientations ranging between 0° and 90°.  Dislocations have a Burgers vector  = a/2 [110]. The elastic energy of dislocation-boundary interaction is calculated within the framework of anisotropic linear elasticity. The elastic energy is related to the difference of the two metals shear moduli. It is about a few hundred pico Joule per meter. The image force can be repulsive or attractive according to the sign and the intensity of shear moduli difference. The isoenergy maps have various symmetries according to the disorientation.

  15. Hotspots engineering by grafting Au@Ag core-shell nanoparticles on the Au film over slightly etched nanoparticles substrate for on-site paraquat sensing.

    Science.gov (United States)

    Wang, Chaoguang; Wu, Xuezhong; Dong, Peitao; Chen, Jian; Xiao, Rui

    2016-12-15

    Paraquat (PQ) pollutions are ultra-toxic to human beings and hard to be decomposed in the environment, thus requiring an on-site detection strategy. Herein, we developed a robust and rapid PQ sensing strategy based on the surface-enhanced Raman scattering (SERS) technique. A hybrid SERS substrate was prepared by grafting the Au@Ag core-shell nanoparticles (NPs) on the Au film over slightly etched nanoparticles (Au FOSEN). Hotspots were engineered at the junctions as indicated by the finite difference time domain calculation. SERS performance of the hybrid substrate was explored using p-ATP as the Raman probe. The hybrid substrate gives higher enhancement factor comparing to either the Au FOSEN substrate or the Au@Ag core-shell NPs, and exhibits excellent reproducibility, homogeneity and stability. The proposed SERS substrates were prepared in batches for the practical PQ sensing. The total analysis time for a single sample, including the pre-treatment and measurement, was less than 5min with a PQ detection limit of 10nM. Peak intensities of the SERS signal were plotted as a function of the PQ concentrations to calibrate the sensitivity by fitting the Hill's equation. The plotted calibration curve showed a good log-log linearity with the coefficient of determination of 0.98. The selectivity of the sensing proposal was based on the "finger print" Raman spectra of the analyte. The proposed substrate exhibited good recovery when it applied to real water samples, including lab tap water, bottled water, and commercially obtained apple juice and grape juice. This SERS-based PQ detection method is simple, rapid, sensitive and selective, which shows great potential in pesticide residue and additives abuse monitoring.

  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. Single-source precursors for alloyed gold-silver nanocrystals - a molecular metallurgy approach.

    Science.gov (United States)

    Zopes, David; Hegemann, Corinna; Schläfer, Johannes; Tyrra, Wieland; Mathur, Sanjay

    2015-04-20

    Multiple silver(I)-aurates(I) have been prepared by salt metathesis reactions that act as efficient single-source precursors to colloidal gold silver alloys with the highest possible atom economy in the chemical synthesis of nanostructures. The CF3 group present on the Au cation acts as an in situ reducing agent and can be converted into CO ligands by simple hydrolysis. This ligand-mediated activation and subsequent decomposition of metal-organic precursors impose a molecular control over the nucleation process, producing homogeneously alloyed (Ag-Au) nanoparticles with an atomic Au:Ag ratio of 1:1. The concept also works for the Au-Cu system and acts as a pointer to replace Au (Ag) with less expensive (Cu) metals.

  18. Electrostatic Radio Frequency (RF) Microelectromechanical Systems (MEMS) Switches With Metal Alloy Electric Contacts

    Science.gov (United States)

    2004-09-01

    Mechanical Testing of Thin Films,” Proc. Transducers 1991 , 943–948 (1991). 163. Wang, Bor-Jenq, Nannaji Saka, and Ernest Rabinowicz . “The Failure...and Ernest Rabinowicz . “Au-Sb and Au-Ag- Sb Alloys as Low-Voltage Contact Metals,” IEEE Trans. on CPMT - Part A, 17 (2):295–302 (June 1994). 165

  19. 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.

  20. Influence of microstructure on quasi-static and dynamic mechanical properties of bismuth-containing lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Witkin, David B., E-mail: david.b.witkin@aero.org [Materials Science Department, Aerospace Corporation, P.O. Box 92957, Mail Stop M2/242, Los Angeles, CA 90009 2957 (United States)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Tensile and dynamic properties of lead-free solder were evaluated. Black-Right-Pointing-Pointer Emphasis on addition of bismuth to alloys and role of isothermal aging. Black-Right-Pointing-Pointer Addition of bismuth increases strength. Black-Right-Pointing-Pointer Strength maintained in Bi-containing alloy after aging, which is opposite of SAC305. Black-Right-Pointing-Pointer Unlike SAC305 damping capacity of Bi-containing changes with aging like SnPb and Sn. - Abstract: The mechanical properties of bulk Pb-free solder alloys containing Bi have been characterized in the as-cast and aged conditions. The alloys were the commercially available Sn-3.4Ag-1.0Cu-3.3Bi and Sn-3.4Ag-4.8Bi (wt.%), which had demonstrated good reliability performance in previous circuit board-level testing programs, but have not been considered for high-volume electronic manufacturing. Room- and elevated-temperature tensile testing showed that the addition of Bi greatly reduced the loss in strength due to aging that occurs in the Sn-Ag-Cu ternary alloys. The room-temperature tensile strength of bulk SAC305 was reduced by 37% after aging at 150 Degree-Sign C for 336 h, but for SAC-Bi the reduction was not statistically meaningful and in SnAg-Bi the tensile strength increased. These differences are attributed to the presence of Bi and its role in solid solution strengthening and precipitation as a separate phase. The damping capacity of the alloys measured by dynamic mechanical analysis showed similar trends, with tan {delta} increasing in aged SAC305 but decreasing in SAC-Bi and SnAg-Bi. The reduction in damping seen in SAC-Bi and SnAg-Bi is consistent with Sn and SnPb eutectic solder, indicating that a general microstructural coarsening is responsible. The increase in damping in SAC305 suggests that the transformation of the ternary eutectic by particle coarsening leads to a continuous {beta}-Sn matrix that contributes to damping.

  1. 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.

  2. 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.

  3. 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.

  4. A model electrode of well-defined geometry prepared by direct laser-induced decoration of nanoporous templates with Au-Ag@C nanoparticles

    Science.gov (United States)

    Schlicht, Stefanie; Kireev, Alexey; Vasileva, Anna; Grachova, Elena V.; Tunik, Sergey P.; Manshina, Alina A.; Bachmann, Julien

    2017-02-01

    We present an original type of model electrode system consisting of bimetallic Au-Ag nanoparticles embedded in an amorphous carbon matrix with an extremely well-defined geometry of parallel, straight, cylindrical macropores. The samples are prepared in one step by direct laser deposition of the metal/carbon composite onto the inner walls of a porous ‘anodic’ alumina matrix serving as a template. The coating is homogeneous from top to bottom of the pores, and the amount of material deposited can be tuned by the duration of the deposition procedure. As a test system, we demonstrate that a bimetallic Ag-Au@C system is catalytically active for the electrochemical oxidation of glucose in alkaline solution, the anodic reaction of a direct glucose fuel cell. Furthermore, the electrocatalytic current density increases with the amount of Ag-Au@C NPs deposited, up to a point at which the pores are clogged with it. This type of model system allows for the systematic study of geometric effects in fuel cell electrodes. It can be generalized to a number of different nanoparticle compositions, and thereby, to various electrocatalytic reactions.

  5. 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.

  6. Alloy

    Science.gov (United States)

    Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

    2014-07-01

    The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by α-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 μm in the extruded ingot, down to 1.6 μm for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

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

    Science.gov (United States)

    dos Santos, Margarida Moreira; Queiroz, Margarida João; Baptista, Pedro V.

    2012-05-01

    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.

  8. 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.

  9. 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.

  10. Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits

    Science.gov (United States)

    Person, M.; Banerjee, A.; Hofstra, A.; Sweetkind, D.; Gao, Y.

    2008-01-01

    The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic fluid source, discharge areas restricted to fault zones, and remarkably high temperatures (>200 ??C) at shallow depths (200-1500 m). While the plumbing of these systems varies, geochemical and isotopic data collected at the Dixie Valley and Beowawe geothermal systems suggest that fluid circulation along fault zones was relatively deep (>5 km) and comprised of relatively unexchanged Pleistocene meteoric water with small (enthalpy, ??18O, silica compositions of fluids and/or rocks, groundwater residence times, fluid inclusion homogenization temperatures, and apatite fission track anomalies. Our results suggest that these hydrothermal systems were driven by natural thermal convection along anisotropic, subvertical faults connected in many cases at depth by permeable aquifers within favorable lithostratigraphic horizons. Those with minimal fluid ?? 18O shifts are restricted to high-permeability fault zones and relatively small-scale (???5 km), single-pass flow systems (e.g., Beowawe). Those with intermediate to large isotopic shifts (e.g., epithermal and Carlin-type Au) had larger-scale (???15 km) loop convection cells with a greater component of flow through marine sedimentary rocks at lower water/rock ratios and greater endowments of gold. Enthalpy calculations constrain the duration of Carlin-type gold systems to probably concentrations suggest that the duration of the modern Beowawe system is enthalpy fluids. Computed fission track ages along the Carlin trend included the convective effects, and ranged between 91.6 and 35.3 Ma. Older fission track ages occurred in zones of

  11. 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

  12. Effect of palladium on sulfide tarnishing of noble metal alloys.

    Science.gov (United States)

    Suoninen, E; Herø, H; Minni, E

    1985-10-01

    Electron spectroscopic studies of Au-Ag-Cu alloys of the type used for dental castings show that small additions (less than or equal to 3 wt%) of palladium reduce essentially the thickness of the sulfide layer formed on surfaces of samples treated in aqueous Na2S solutions. Relative to silver, palladium does not enrich in the sulfide, but statistically significant enrichment is found immediately below the sulfide layer. This enrichment probably takes place during the exposure of the substrate surface to atmosphere before the sulfiding treatment. The mechanism of the impeding effect of palladium on sulfiding is assumed to be a decrease in diffusion from the bulk alloy to the surface due to the enriched layer. The effect cannot be explained by changes in the electronic structure of the alloy due to palladium alloying.

  13. Determination of the surface composition of binary alloys by Auger electron spectroscopy: the gold--silver and gold--tin systems

    Energy Technology Data Exchange (ETDEWEB)

    Overbury, S.H.

    1976-11-01

    Auger electron spectroscopy was exploited as a means of determining the surface phase diagram of Au--Ag and Au--Sn alloys. Polycrystalline Au--Ag alloy foils of a wide range of composition (atom fractions of 0.15 to 0.97) were cleaned. The intensities of the Auger emission from transitions at several energies were measured and normalized to those of pure Au and Ag. The surface monolayer compositions of the alloys were determined. The Auger data was consistent with enrichment of Ag in the surface monolayer. Ingots of Au--Sn with bulk composition between 50 and 99 at % Au were prepared. The bulk structure and composition of these complex alloys were characterized by electron microprobe, x-ray diffraction, x-ray fluorescence and optical microscopy. The samples were cleaned and equilibrated in ultra high vacuum and the intensities of the Auger emission from transitions at several energies were measured and normalized to those of pure Au and pure Sn. Using the intensity model, the normalized Auger intensity ratios were used to determine the surface monolayer composition. Enrichment of Sn was found in the surface monolayer for disordered zeta and ..cap alpha.. phase alloys. The highly ordered delta (50.0 at % Au) phase alloy was found to exhibit no surface segregation. The surfaces of two phase alloys (delta and zeta) were found to be describable by the lever rule. The results were interpreted in terms of the bulk structures, ordering properties, and driving force for segregation of the alloys. The effects of ion sputtering upon the surface of Au--Ag and Au--Sn alloys were also investigated.

  14. Effects of Static Magnetic Field on Solidification Structure of 2024 Aluminum Alloy%静磁场对2024铝合金凝固组织的影响

    Institute of Scientific and Technical Information of China (English)

    程常桂; 余乐; 万文成; 刘中天; 金焱

    2012-01-01

    Effects of static magnetic on the microscopic grain density, solidification rate and distribution of alloy elements in 2024 aluminum alloy were investigated by means of thermal simulation experiment and scanning electron microscope (SEM). The results show that the solidification structure can be refined with increasing in magnetic intensity, and the solidification time is decreased, which are closely related to the Seebeck effect acting on liquid metal in solidification front as a result of enhancing the flow of liquid metal and inhibiting the electromagnetic brake effects. Furthermore, the static magnetic field can promote disfussion of solute atoms in aluminum alloy, and it is favorable to improving solid solubility of alloy elements and decreasing macro-segregation of 2024 aluminum alloy.%通过热模拟试验及扫描电镜分析,研究了静磁场对2024铝合金显微晶粒度、凝固速度、合金元素分布的影响.结果表明,随着磁感应强度的增大,合金凝固组织明显细化,凝固时间变短,这与凝固前沿熔体内的塞贝克效应有关,使得熔体对流效应强于静磁场的制动效应;应用静磁场能够增强溶质原子在铝中的扩散,有利于提高合金元素的固溶度,减轻凝固组织的宏观偏析.

  15. 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 <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

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

    OpenAIRE

    Katayon Bahrami; Pardis Nazari; Mahshid Nabavi; Marjan Golkar; Ali Almasirad; Ahmad Reza Shahverdi

    2014-01-01

      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 pu...

  17. 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 [Pall Corporation, Port Washington, NY (United States); Zhao, Hongbin [Pall Corporation, Port Washington, NY (United States); Hopkins, Scott [Pall Corporation, Port Washington, NY (United States)

    2014-12-01

    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.

  18. 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.

  19. 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.

  20. Effects of silicon, copper and iron on static and dynamic properties of alloy 206 (aluminum-copper) in semi-solids produced by the SEED process

    Science.gov (United States)

    Lemieux, Alain

    The advantages of producing metal parts by rheocasting are generally recognised for common foundry alloys of Al-Si. However, other more performing alloys in terms of mechanical properties could have a great interest in specialized applications in the automotive industry, while remaining competitive in the forming. Indeed, the growing demand for more competitive products requires the development of new alloys better suited to semi-solid processes. Among others, Al-Cu alloys of the 2XX series are known for their superior mechanical strength. However, in the past, 2XX alloys were never candidates for pressure die casting. The main reason is their propensity to hot tearing. Semi-solid processes provide better conditions for molding with the rheological behavior of dough and molding temperatures lower reducing this type of defect. In the initial phase, this research has studied factors that reduce hot tearing susceptibility of castings produced by semi-solid SEED of alloy 206. Subsequently, a comparative study on the tensile properties and fatigue was performed on four variants of the alloy 206. The results of tensile strength and fatigue were compared with the specifications for applications in the automotive industry and also to other competing processes and alloys. During this study, several metallurgical aspects were analyzed. The following main points have been validated: i) the main effects of compositional variations of silicon, iron and copper alloy Al-Cu (206) on the mechanical properties, and ii) certain relationships between the mechanism of hot cracking and the solidification rate in semi-solid. Parts produced from the semi-solid paste coming from the SEED process combined with modified 206 alloys have been successfully molded and achieved superior mechanical properties than the requirements of the automotive industry. The fatigue properties of the two best modified 206 alloys were higher than those of A357 alloy castings and are close to those of the

  1. Correlation between band structure and hydride formation in dilute palladium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bucur, R.V.; Lupu, D.

    1982-01-01

    Data on the free energy change /DELTA/G, following solution of hydrogen in dilute Pd-alloys Pd/sub 1-x/M/sub x/ are reviewed for different concentrations of M (M = Au, Ag, Pt, Ir, Rh, V, Cu, Ni, Pb, Sn and Ti) in both the /alpha/ and /beta/ phases. It is found that the dependence of /DELTA/G values upon the nature of the substituents (transition metals) is consistently explained within the framework of a metal-hydrogen bonding mechanisn in the hydrides. 23 refs.

  2. Fabrication and characterization of thermo-responsive composite microgels based on Au@Ag nanorod as core%以Au@Ag双金属纳米棒为核的热响应性核壳复合微凝胶的制备及性能表征

    Institute of Scientific and Technical Information of China (English)

    董旭; 刘晓云; 周剑锋; 张莉; 林丹丽; 查刘生

    2015-01-01

    本文采用种子沉淀聚合法将交联的聚( N-异丙基丙烯酰胺)( PNIPAM)包覆在单分散性良好的Au@Ag双金属纳米棒( Au@AgNR)表面,制得以Au@AgNR为核、交联PNIPAM为壳层的Au@AgNR@PNIPAM复合微凝胶。用透射电镜观察到复合微凝胶具有规整的核壳结构,动态激光光散射测试结果证实复合微凝胶存在热响应性。当环境温度从20℃升高到50℃,复合微凝胶中Au@AgNR的纵向局域表面等离子体共振波长从695nm红移到719nm,表明复合微凝胶内的Au@AgNRs的LSPR光学性能可利用温度来进行调节。以该复合微凝胶为SERS分析的基底,检测水溶液中痕量的难以吸附在金属粒子表面的1-萘酚(3×10-5 M),结果发现复合微凝胶在发生体积相转变时对1-萘酚具有捕捉效应,因此可通过调节测试温度来达到提高待分析物的SERS的信号强度的目的。%The composite microgels based on Au@Ag bimetallic nanorod( Au@AgNR) as core and crosslinked poly( N-isopropylac-rylamide)(PNIPAM)as shell(Au@AgNR@PNIPAM composite microgels)were prepared by seed precipitation. The core-shell structure of the composite microgels was visualized by electron transmission microscopy,and their thermo-responsive property was i-dentified by measuring their temperature dependent particle size using dynamic light scattering technique. As environmental temper-ature was raised from 20 to 50℃,the longitudinal localized surface plasmon resonance wavelength of Au@AgNR within the compos-ite microgels measured by temperature variable ultraviolet visible near-infrared spectroscopy was red-shifted from 695 to 719 nm,in-dicating that their plasmonic property is temperature-tunable. When the composite microgels are used as SERS substrates for detec-tion of 3×10-5 M 1-naphthol in aqueous solution,it found that the composite microgels has entrappment effect for the analyte during their temperature triggered volume phase transition,and the SERS signal strength can be

  3. 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...... 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...

  4. Corrosion evaluation of gold-based dental alloys.

    Science.gov (United States)

    Corso, P P; German, R M; Simmons, H D

    1985-05-01

    Three commercial gold-based dental alloys and three constant-nobility ternary alloys (Au-Ag-Cu) were evaluated for corrosion using a quantitative test battery. Integration of the current density, in a de-aerated solution of 1% NaCl along the approximate potential range found in the mouth (-300 mV to +300 mV vs. SCE), yields a quantitative rank ordering of the test alloys. The results are combined with prior findings on other commercial alloys to demonstrate the interaction of nobility and microstructure. Nobility determines the overall corrosion resistance for gold-based alloys. However, because of mutual insolubility, alloying with copper induces silver segregation, resulting in a higher corrosion rate at a given nobility. Thus, microstructure has an influence on corrosion, but heat treatments are largely ineffective in altering the basic corrosion characteristics. The test techniques, in combination with tarnish evaluations, provide a quantitative battery for alloy evaluation. The results indicate the combinations of nobility, microstructure, and environment most likely to avoid corrosion difficulties.

  5. 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.

  6. Influence of joint line remnant on crack paths under static and fatigue loadings in friction stir welded Al-Mg-Sc alloy

    Directory of Open Access Journals (Sweden)

    Y. Besel

    2016-01-01

    Full Text Available The influence of the joint line remnant (JLR on tensile and fatigue fracture behaviour has been investigated in a friction stir welded Al-Mg-Sc alloy. JLR is one of the microstructural features formed in friction stir welds depending on welding conditions and alloy systems. It is attributed to initial oxide layer on butting surfaces to be welded. In this study, two different tool travel speeds were used. JLR was formed in both welds but its spatial distribution was different depending on the tool travel speeds. Under the tensile test, the weld with the higher heat input fractured partially along JLR, since strong microstructural inhomogeneity existed in the vicinity of JLR in this weld and JLR had weak bonding. Resultantly, the mechanical properties of this weld were deteriorated compared with the other weld. Fatigue crack initiation was not affected by the existence of JLR in all welds. But the crack propagated preferentially along JLR in the weld of the higher heat input, when it initiated on the retreating side. Consequently, such crack propagation behaviour along JLR could bring about shorter fatigue lives in larger components in which crack growth phase is dominant.

  7. Formation of Star-Like and Core-Shell AuAg Nanoparticles during Two- and Three-Step Preparation in Batch and in Microfluidic Systems

    Directory of Open Access Journals (Sweden)

    J. Michael Köhler

    2007-01-01

    Full Text Available Regular dendrit-like metal nanoparticles and core-shell nanoparticles were formed by the reduction of mixtures of tetrachloroaurate and silver nitrate solutions with ascorbic acid at room temperature in two- and three-step procedures. The formation of these particles was found in batch experiments as well as in micro flow-through processes using static micromixers. The characteristic diameters of 4-branched star particles were in the range between 60 and 100 nm. The typical particles consist of four metal cores which are embedded in a common shell. Additionally, particles with five and more metallic cores were formed, to some extent, and aggregates of the 4-branched particles also were formed. Larger aggregates and network-like structures of connected star particles were formed after sedimentation. The properties of the formed particles are dependent on the educt concentrations as well as on the order of mixing steps and on the time interval between them. Obviously, the relation of nucleation and particle growth in relation to the concentrations of metal ions determines the composition and the properties of formed nanoparticles. So, star-like particles are observed in case of nucleation of Au in absence of silver ions but with silver deposition after short nucleation time. Spherical core shell particles are formed in case of silver salt addition after complete reduction of tetrachloroaurate in flow-through experiments with sufficient residence time between both mixing steps. Polymer layers are always found in the form of a second outer shell even if the polymer solutions are added in an early stage of particle formation.

  8. Unit Cell Analysis of the Superelastic Behavior of Open-Cell Tetrakaidecahedral Shape Memory Alloy Foam under Quasi-Static Loading

    Directory of Open Access Journals (Sweden)

    Guillaume Maîtrejean

    2014-01-01

    Full Text Available Cellular solid materials and, more specifically, foams are increasingly common in many industrial applications due to their attractive characteristics. The tetrakaidecahedral foam microstructure, which can be observed in many types of foams, is studied in the present work in association with shape memory alloys (SMA material. SMA foams are of particular interest as they associate both the shape memory effect and the superelasticity with the characteristics of foam. A Unit Cell Finite Element Method approach is used, an approach that allows accurate predicting of the macroscale response of the foam with a highly reduced numerical effort. The tetrakaidecahedral foam’s responses, both in the elastic and in the superelastic stages, are then extracted and compared with results from the literature. The tetrakaidecahedral geometry is found to be of particular interest when associated with SMA as it takes more advantage of the superelastic property of the material than foams with randomly distributed porosity.

  9. Effect of twin boundary on static recrystallization of AZ31 magnesium alloy%孪晶界对AZ31镁合金静态再结晶的影响

    Institute of Scientific and Technical Information of China (English)

    丁雪征; 刘天模; 陈建; 张瑜; 卢立伟

    2013-01-01

      对铸态AZ31镁合金进行不同变形量的锻造或压缩室温变形,然后经过不同温度和时间的退火保温,研究孪晶界对合金静态再结晶过程的影响。结果表明,锻造产生的孪晶较短且取向错乱,而压缩变形产生的孪晶则较狭长,同取向的孪晶大量聚集、平行排列,这与锻造和压缩两种变形方式的形变速率不同有关。退火保温实验结果表明,在相同条件下,锻造变形镁合金孪晶处比压缩变形镁合金孪晶处更易发生再结晶。研究不同孪晶处的形核方式,提出低温“孪晶界凸出形核”机理,发现某些孪晶变体即二次孪晶处并不是优先形核的位置,这与经典的孪生形核理论的观点不同。%The effect of twin boundary during static recrystallization of the as­cast AZ31 magnesium alloy annealed at different temperatures for different times was studied after being forged or compressed with certain proportion. The results show that the twins produced by forging are short and their orientations are disordered, but twins produced by compression are narrow and long and exist with groups that have the same orientation. The morphology differences of diverse deformation are related to the difference of deformation rate of the forging and compression. Annealing experiments results show that under the same condition, the recrystallization at twin boundaries of the forged AZ31 magnesium alloy occurs more easily than that of the compressed AZ31 magnesium alloy. Moreover, the nucleation ways in the diverse areas of twin boundary were studied. A new nucleation theory of “twin boundary bulge nucleation mechanism” at low temperature was proposed. The results indicate that some twin variants are not the positions for priority nucleation, which is different from the classic twin nucleation theory.

  10. 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.

  11. Synthesis of Au, Ag, Curcumin Au/Ag, and Au-Ag Nanoparticles and Their Nonlinear Refractive Index Properties

    Directory of Open Access Journals (Sweden)

    F. Abdulwahab

    2016-01-01

    Full Text Available Nanoparticles of gold and silver were prepared by a reduction method and by employing green chemistry principles such as using curcumin as a reducing and a stabilizing agent. The formation of nanoparticles was confirmed by UV-Vis absorption spectra and TEM. Mie theory was used to determine the particle sizes. The nonlinear refraction and absorption properties of the particles were measured using the z-scan technique. A large value of third-order nonlinearities was obtained using the nanoparticles produced.

  12. Synthesis of Au, Ag, Curcumin Au/Ag, and Au-Ag Nanoparticles and Their Nonlinear Refractive Index Properties

    OpenAIRE

    F. Abdulwahab; Henari, F Z; Cassidy, S.; Winser, K.

    2016-01-01

    Nanoparticles of gold and silver were prepared by a reduction method and by employing green chemistry principles such as using curcumin as a reducing and a stabilizing agent. The formation of nanoparticles was confirmed by UV-Vis absorption spectra and TEM. Mie theory was used to determine the particle sizes. The nonlinear refraction and absorption properties of the particles were measured using the z-scan technique. A large value of third-order nonlinearities was obtained using the nanoparti...

  13. Explosive device of conduit using Ti Ni alloy

    Directory of Open Access Journals (Sweden)

    A. Yu. Kolobov

    2014-01-01

    Full Text Available Presently, materials have been developed which are capable at changing temperate to return significant inelastic deformations, exhibit rubber-like elasticity, convert heat into mechanical work, etc. The aggregate of these effects is usually called the shape memory effect.At present a great number of compounds and alloys with a shape memory effect has been known.These are alloys based on titanium nickelide (TiNi, copper-based alloys (Cu-Al, Cu-Sn, Cu-Al-Ni, Cu-Zn-Si, etc., gold and silver (Ag-Cd, Au-Ag-Cd, Au-Cd-Cu, Au-Zn-Cu, etc., manganese (Mn-Cr, Fe-Cu, Mn-Cu-Ni, Mn-Cu-Zr, Mn-Ni, etc., iron (Fe-Mn, Fe-Ni, Fe-Al, etc., and other compounds.The alloys based on titanium nickelide (nitinol are the most widely used.Alloys with shape memory effect find various applications in engineering and medicine, namely connecting devices, actuators, transformable design, multipurpose medical implants, etc.There is a task of breaking fuel conduit during separating the spacecraft from the rocket in space technology.The paper examines the procedure for design calculation of the separating device of conduit with the use of Ti-Ni alloy. This device can be used instead of the pyro-knives.The device contains two semi-rings from Ti-Ni alloy. In the place of break on the conduit an annular radius groove is made.At a temperature of martensite passage the semi-rings undergo deformation and in the strained state are set in the device. With heating to the temperature of the austenitic passage of bushing macro-deformation the energy stored by the nitinol bushing is great enough to break the conduit on the neck.The procedures of design calculation and response time of device are given.

  14. 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

  15. Studies on Determination of Ge in Au Alloys by Potassium Iodate Potentiometric Titration Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Liya; XIE Hongchao; CHEN Liangwei; ZHOU Yu; TAN Yanshan; LIU Wen; LI Yong; HAN Shouli; TAN Wenjin; HE Xiaotan; WU Xilong

    2012-01-01

    Abstraction:The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation.The influences of conditions such as the reduction acidity,dosage of sodium hypophosphite and reduction time on the determination of Ge were studied.Comparison was made between the influences of end-point indication for potential method and starch method on accruracy and precision of the analysed results,stability and sensitivity of end-point,selectivity of method and so on.The possibility of reaction in an electrochemical way was discussed.Ge in the alloys such as AuGe12,AuGeNi12-2,AuAgGe18.8-12.5 and AuAgGeNi43.8-6-0.2 was measured,respectively,with the relative standard deviation of 0.10%~0.31% and the recoveries of added standard Ge in sample of 99.40%~100.40% when the reduction acidity was 0.40~0.80 mol/L HC1 and 3.3 mol/L H3PO4,15 g sodium hypophosphite and reduction time 40 min.The new method presented is high accuracy and precision in results,good stability and sensibility in end-point,easy operation and strong selectivity of determination.When it is applied to analyse actual samples,satisfactory results are achieved.

  16. Stable-isotope geochemistry of the Pierina high-sulfidation Au-Ag deposit, Peru: Influence of hydrodynamics on SO42--H2S sulfur isotopic exchange in magmatic-steam and steam-heated environments

    Science.gov (United States)

    Fifarek, R.H.; Rye, R.O.

    2005-01-01

    The Pierina high-sulfidation Au-Ag deposit formed 14.5 my ago in rhyolite ash flow tuffs that overlie porphyritic andesite and dacite lavas and are adjacent to a crosscutting and interfingering dacite flow dome complex. The distribution of alteration zones indicates that fluid flow in the lavas was largely confined to structures but was dispersed laterally in the tuffs because of a high primary and alteration-induced permeability. The lithologically controlled hydrodynamics created unusual fluid, temperature, and pH conditions that led to complete SO42--H2S isotopic equilibration during the formation of some magmatic-steam and steam-heated alunite, a phenomenon not previously recognized in similar deposits. Isotopic data for early magmatic hydrothermal and main-stage alunite (??34S=8.5??? to 31.7???; ??18 OSO4=4.9??? to 16.5???; ??18 OOH=2.2??? to 14.4???; ??D=-97??? to -39???), sulfides (??34 S=-3.0??? to 4.3???), sulfur (??34S=-1.0??? to 1.1???), and clay minerals (??18O=4.3??? to 12.5???; ??D=-126??? to -81???) are typical of high-sulfidation epithermal deposits. The data imply the following genetic elements for Pierina alteration-mineralization: (1) fluid and vapor exsolution from an I-type magma, (2) wallrock buffering and cooling of slowing rising vapors to generate a reduced (H2S/SO4???6) highly acidic condensate that mixed with meteoric water but retained a magmatic ??34S???S signature of ???1???, (3) SO2 disproportionation to HSO4- and H2S between 320 and 180 ??C, and (4) progressive neutralization of laterally migrating acid fluids to form a vuggy quartz???alunite-quartz??clay???intermediate argillic???propylitic alteration zoning. Magmatic-steam alunite has higher ??34S (8.5??? to 23.2???) and generally lower ??18OSO4 (1.0 to 11.5???), ??18OOH (-3.4 to 5.9???), and ??D (-93 to -77???) values than predicted on the basis of data from similar occurrences. These data and supporting fluid-inclusion gas chemistry imply that the rate of vapor ascent for this

  17. 温度对Zr-45Ti-5Al-3V合金准静态力学性能的影响%INFLUENCE OF TEMPERATURE ON QUASI-STATIC MECHANICAL PROPERTIES OF Zr-45Ti-5Al-3V ALLOY

    Institute of Scientific and Technical Information of China (English)

    刘丁铭; 张波; 王杰; 王爱民; 王沿东; 张海峰; 胡壮麒

    2014-01-01

    在-100~200℃范围内不同应变速率(10-4,10-3和10-2s-1)下利用准静态拉伸和压缩实验研究了温度对Zr-45Ti-5Al-3V合金力学性能的影响.结果表明,在拉伸条件下,Zr-45Ti-5Al-3V合金具有较高的屈服强度和抗拉强度,室温时其屈服强度超过1355 MPa,但延伸率较小.随着温度的升高,合金的屈服强度和抗拉强度均下降,而塑性变形量则上升.在压缩条件下,温度对屈服强度的影响与拉伸时一致,而塑性变形量和断裂强度均在室温时最高,其他温度下变化规律与拉伸时一致.应变速率对合金的力学性能影响不大.%Zr alloys are widely used in pressurized-water reactors as fuel cladding materials due to their low neutron absorption cross section and excellent radiation resistance.Aside from the aforementioned properties,Zr alloys have high strength,relative low density and many other excellent physical and chemical properties that make them promising structural materials used in the aerospace environment.Zr-45Ti-5Al-3V alloy is a high strength zirconium alloy which is newly developed for use in aerospace environment.The temperature in space environment can change from-100 ℃ to more than 100 ℃,so it is necessary to study the mechanical behavior of Zr-45Ti-5Al-3V alloy under different temperatures.In this work,mechanical properties of Zr-45Ti-5Al-3V alloy under different temperatures (-100,25,100 and 200 ℃) and strain rates (10-4,10-3 and 10-2 s-1) were investigated.The microstructure of the Zr-45Ti-5Al-3V alloy is characterized by SEM and XRD.It is shown that the alloy is comprised of two phases:a lath-like α phase with hcp structure is distributed uniformly in the matrix comprised of a β phase with bcc structure.Quasi-static mechanical properties of Zr-45Ti-5Al-3V alloy were studied in temperature range of-100~200 ℃ under various strain rates (10-4,10-3 and 10-2 s-1) using the Instron 5528 electric universal material testing machine.The results

  18. Geological characteristics and clues for prospecting of Weishancheng Au-Ag metallogenic belt in Tongbo of Henan%河南桐柏围山城金、银成矿带矿床地质特征及找矿标志

    Institute of Scientific and Technical Information of China (English)

    徐春林

    2014-01-01

    Weishancheng Au-Ag metallogenic belt deposit is located at north subzone of Tongbo-Dabieshan (north slope)Au-Ag metallogenic belt.The orebodies mainly occur in carbon-bearing sericitic quartz schist of Epiproterozoic Waitoushan groups and it is under strict control of tectonic setting.The ore-bearing forma-tion is affected by hydrothermal fluid and generates different alteration,while mineralization is closely relat-ed to silicification.The mining area has favorable mineral-formation conditions and abundant resource.Based on the detailed analysis of formations,rocks,structure and wall rock alteration in the mining area,the au-thor proposes clues for prospecting.%围山城金银成矿带矿床位于桐柏-大别山(北坡)金银成矿带北亚带。矿体主要赋存于上元古界歪头山组炭质绢云石英片岩内,严格受构造条件控制,含矿层受热液作用影响产生不同蚀变,尤其硅化与矿化的关系最为密切。矿区成矿地质条件优越,资源丰富。笔者在对矿带内地层、岩石、构造、围岩蚀变等较为详细分析的基础上提出了找矿标志。

  19. MICROSTRUCTURE EVOLUTION AND STATIC RECRYS-TALLIZATION BEHAVIOR OF HOT-ROLLED Mg-1Zn AND Mg-1Y ALLOYS DURING ISOTHERMAL ANNEALING%热轧Mg-1Zn和Mg-1Y合金退火组织演变及静态再结晶行为

    Institute of Scientific and Technical Information of China (English)

    刚建伟; 施斌卿; 陈荣石; 柯伟

    2012-01-01

    对比研究了高温轧制制备的Mg-1.02Zn及Mg-0.76Y(质量分数,%)合金在不同温度退火条件下的组织演变及静态再结晶和晶粒长大动力学行为.结果表明,Mg-1Zn合金的轧制组织以剪切带和孪晶为主,在剪切带和孪晶内伴随着动态再结晶;而Mg-1Y合金的轧制组织中只有孪晶,未观察到剪切带和再结晶发生.退火过程中,Mg-1Zn合金静态再结晶过程主要受控于形核过程,而Mg-1Y合金则既受控于形核过程又受控于长大过程.利用经典的JMAK模型和长大模型分别描述了2种合金热轧制后的静态再结晶和晶粒长大动力学过程,结果表明,静态再结晶过程的Avrami因子n值与理想预测值偏离可能来自于再结晶的不均匀形核.固溶稀土Y原子比Zn原子对晶界移动的拖曳作用更强,导致Mg-1Y合金比Mg-1Zn合金晶粒长大因子n'更高.%Wrought Mg alloys alloyed with rare elements (RE) addition were deemed to be one of the most promising Mg alloys in industrial application, due to the formation of weakened texture and refined microstructure. Generally, the wrought Mg alloys with RE addition after normal thermal-mechanical processing possessed incompletely recrystallized microstructure, so it was necessary to research the subsequent annealing treatment for controlling the microstructure. Unfortunately, the corresponding investigations on the mentioned above were still limited. In this study, hot-rolled Mg-1.02Zn and Mg-0.76Y (mass fraction, %) alloys were selected to investigate the microstructure evolution, static recrystallization behavior and grain growth kinetics under different annealing treatments. The microstructure examination showed that hot-rolled Mg lZn alloy was composed of shear bands and twinswith the occurrence of dynamic recrystallization; whereas only twins were observed in the hot-rolled Mg-IY alloy, no shear bands and recrystallization were detected. That should be attributed to the difference in the

  20. 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

  1. Morphology, stresses, and surface reactivity of nanoporous gold synthesized from nanostructured precursor alloys

    Science.gov (United States)

    Rouya, Eric

    Nanoporous metallic materials (NMMs) are generally synthesized using dealloying, whereby the more reactive component is dissolved from a homogeneous alloy in a suitable electrolyte, and the more noble metal atoms simultaneously diffuse into 3-D clusters, forming a bi-continuous network of interconnected ligaments. Nanoporous gold (NPG) in particular is a well-known NMM; it is inert, bio-compatible, and capable of developing large surface areas with 1--100nm pores. While several studies have demonstrated its potential usefulness in fuel cell and sensing devices, its structural, mechanical, and electrocatalytic properties still require further investigation, particularly if NPG is synthesized from precursor alloy films exhibiting metastable nanostructures. In this dissertation, the electrodeposition (ECD) process, microstrucural characteristics, and metatstability of Au-Ni precursor alloys are investigated. The stresses evolved during Au-Ni alloy nucleation and growth are investigated in situ and correlated with microstructural and electrochemical data in order to identify the various stress-inducing mechanisms. In situ stresses generated during Au-Ni and Au-Ag dealloying were investigated, and additionally correlated with the growth stresses. Finally, the surface area and electrocatalytic properties of NPG are characterized using a variety of electrochemical techniques. Potentiostatically electrodeposited Au1-x-Nix (x: 0--90at%) films form a continuous series of metastable solid solutions and exhibit a nanocrystalline morphology, with ˜10--20 nm grains, the size of which decreases with increasing Ni content. The formation of a metastable structure was interpreted in terms of the limited surface diffusivities of adatoms at the growing interface and atomic volume differences (˜15%). Internal stresses generated during ECD of Ni-rich films can be explained assuming a 3-D Volmer-Weber growth mode, where the stress is initially compressive, then transitions into tension

  2. Laser-induced damage thresholds of gold, silver and their alloys in air and water

    Science.gov (United States)

    Starinskiy, Sergey V.; Shukhov, Yuri G.; Bulgakov, Alexander V.

    2017-02-01

    The nanosecond-laser-induced damage thresholds of gold, silver and gold-silver alloys of various compositions in air and water have been measured for single-shot irradiation conditions. The experimental results are analyzed theoretically by solving the heat flow equation for the samples irradiated in air and in water taking into account vapor nucleation at the solid-water interface. The damage thresholds of Au-Ag alloys are systematically lower than those for pure metals, both in air and water that is explained by lower thermal conductivities of the alloys. The thresholds measured in air agree well with the calculated melting thresholds for all samples. The damage thresholds in water are found to be considerably higher, by a factor of ∼1.5, than the corresponding thresholds in air. This cannot be explained, in the framework of the used model, neither by the conductive heat transfer to water nor by the vapor pressure effect. Possible reasons for the high damage thresholds in water such as scattering of the incident laser light by the vapor-liquid interface and the critical opalescence in the superheated water are suggested. Optical pump-probe measurements have been performed to study the reflectance dynamics of the surface irradiated in air and water. Comparison of the transient reflectance signal with the calculated nucleation dynamics provides evidence that the both suggested scattering mechanisms are likely to occur during metal ablation in water.

  3. Rectifier cabinet static breaker

    Science.gov (United States)

    Costantino, Jr, Roger A.; Gliebe, Ronald J.

    1992-09-01

    A rectifier cabinet static breaker replaces a blocking diode pair with an SCR and the installation of a power transistor in parallel with the latch contactor to commutate the SCR to the off state. The SCR serves as a static breaker with fast turnoff capability providing an alternative way of achieving reactor scram in addition to performing the function of the replaced blocking diodes. The control circuitry for the rectifier cabinet static breaker includes on-line test capability and an LED indicator light to denote successful test completion. Current limit circuitry provides high-speed protection in the event of overload.

  4. 从含高铜铅氰化金泥中提取金、银、铜、铅全湿法工艺%Total-wet method to extract Au, Ag, Cu and Pb from cyanidation gold-slime containing high copper and lead

    Institute of Scientific and Technical Information of China (English)

    胡宪

    2011-01-01

    A total-wet method to extract Au, Ag, Cu and Pb from cyanidation gold-slime containing high copper and lead is put forward by experiments.The gold slim is pretreated by adding a sort of decoppering agent in the sulfuric acid medium, and the decoppering rate is 98 %.The gold extraction rate from the extracting slag after pretreatment is 99.5 %.Sponge gold is reduced with mixed reducer,and after impurity removement, the gold purity meets the Au-2 standard.%根据试验结果,提出了一种从含高铜铅氰化金泥中提取Au、Ag、Cu、Pb全湿法工艺.该工艺在硫酸介质中加入一种除铜剂对氰化金泥进行预处理,除铜率达98%;预处理后的含金渣浸金,金浸出率达99.5%以上;用混合还原荆还原出的海绵金,经去杂处理,金的成色达到Au-2标准.

  5. Static Analysis Numerical Algorithms

    Science.gov (United States)

    2016-04-01

    STATIC ANALYSIS OF NUMERICAL ALGORITHMS KESTREL TECHNOLOGY, LLC APRIL 2016 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION...3. DATES COVERED (From - To) NOV 2013 – NOV 2015 4. TITLE AND SUBTITLE STATIC ANALYSIS OF NUMERICAL ALGORITHMS 5a. CONTRACT NUMBER FA8750-14-C... algorithms , linear digital filters and integrating accumulators, modifying existing versions of Honeywell’s HiLiTE model-based development system and

  6. 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.

  7. 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.

  8. 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

  9. Static Transition Compression

    DEFF Research Database (Denmark)

    Danvy, Olivier; Damian, Daniel

    2001-01-01

    Starting from an operational specification of a translation from a structured to an unstructured imperative language, we point out how a compositional and context-insensitive translation gives rise to static chains of jumps. Taking an inspiration from the notion of continuation, we state a new...... 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...

  10. Gold-silver alloy nanoshells: a new candidate for nanotherapeutics and diagnostics

    Directory of Open Access Journals (Sweden)

    Karmonik Christof

    2011-01-01

    Full Text Available Abstract We have developed novel gold-silver alloy nanoshells as magnetic resonance imaging (MRI dual T 1 (positive and T 2 (negative contrast agents as an alternative to typical gadolinium (Gd-based contrast agents. Specifically, we have doped iron oxide nanoparticles with Gd ions and sequestered the ions within the core by coating the nanoparticles with an alloy of gold and silver. Thus, these nanoparticles are very innovative and have the potential to overcome toxicities related to renal clearance of contrast agents such as nephrogenic systemic fibrosis. The morphology of the attained nanoparticles was characterized by XRD which demonstrated the successful incorporation of Gd(III ions into the structure of the magnetite, with no major alterations of the spinel structure, as well as the growth of the gold-silver alloy shells. This was supported by TEM, ICP-AES, and SEM/EDS data. The nanoshells showed a saturation magnetization of 38 emu/g because of the presence of Gd ions within the crystalline structure with r 1 and r 2 values of 0.0119 and 0.9229 mL mg-1 s-1, respectively (Au:Ag alloy = 1:1. T 1- and T 2-weighted images of the nanoshells showed that these agents can both increase the surrounding water proton signals in the T 1-weighted image and reduce the signal in T 2-weighted images. The as-synthesized nanoparticles exhibited strong absorption in the range of 600-800 nm, their optical properties being strongly dependent upon the thickness of the gold-silver alloy shell. Thus, these nanoshells have the potential to be utilized for tumor cell ablation because of their absorption as well as an imaging agent.

  11. Alloy formation during the electrochemical growth of a Ag-Cd ultrathin film on Au(1 1 1)

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, M.C. del; Garcia, S.G. [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina); Salinas, D.R., E-mail: dsalinas@uns.edu.a [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina)

    2009-12-30

    The electrodeposition of a Ag/Cd ultrathin film on a Au(1 1 1) surface and the formation of a surface alloy during this process have been studied using classical electrochemical techniques and in situ Scanning Tunneling Microscopy (STM). The films were obtained from separate electrolytes containing Ag{sup +} or Cd{sup 2+} ions and from a multicomponent solution containing both ions. First, the polarization conditions were adjusted in order to form a Ag film by overpotential deposition. Afterwards, a Cd monolayer was formed onto this Au(1 1 1)/Ag modified surface by underpotential deposition. The voltammetric behavior of the Cd UPD and the in situ STM images indicated that the ultrathin Ag films were uniformly deposited and epitaxially oriented with respect to the Au(1 1 1) surface. Long time polarization experiments showed that a significant Ag-Cd surface alloying accompanied the formation of the Cd monolayer on the Au(1 1 1)/Ag modified surface, independent of the Ag film thickness. In the case of an extremely thin Ag layer (1 Ag ML) the STM images and long time polarization experiments revealed a solid state diffusion process of Cd, Ag, and Au atoms which can be responsible for the formation of different Ag-Cd or Au-Ag-Cd alloy phases.

  12. Behavior of intermetallics formation and evolution in Ag–8Au–3Pd alloy wire bonds

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rui [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Hang, Tao, E-mail: hangtao@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Mao, Dali [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Li, Ming, E-mail: mingli90@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Qian, Kaiyou; Lv, Zhong; Chiu, Hope [Packaging RnD and Advanced MFG Engineering, SanDisk Semiconductor (Shanghai) Co., Ltd., Shanghai (China)

    2014-03-05

    Highlights: • Two IMC layers formed between Ag–8Au–3Pd alloy wire and Al pad were identified. • IMCs growth during annealing was discussed by diffusion kinetics. • Ag diffusion controls voids filling at bonding interface during thermal aging. -- Abstract: Ag–8Au–3Pd alloy wire has shown promise as an economical substitute for gold wire interconnects from integrated circuits to substrates. This work is undertaken to gain a better understanding on the intermetallic compounds (IMC) formation and evolution at the interface between Ag–8Au–3Pd wire and Al metallization pad. Longitudinal cross-section of bond interface was prepared by dual-beam focused ion beam (FIB) micro-machining for transmission electron microscopy (TEM) analysis. Two intermetallic regions formed at interface were crystallochemically identified as AuAl{sub 2} + (Au, Ag){sub 4}Al and Ag{sub 2}Al respectively. Interface evolution tracking by back scattered electron (BSE) imaging showed that IMC initially formed at periphery of bonding area. After short-term annealing treatment (175 °C for 24 h), the voids in the center of the bonding interface shrank and vanished, due to the Ag diffusion played dominant part in IMC growing. The mechanism of IMC formation and evolution at interface was finally elaborated on the basis of thermodynamics and diffusion kinetics respectively.

  13. Method of producing superplastic alloys and superplastic alloys produced by the method

    Science.gov (United States)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  14. Why Static Clings

    Science.gov (United States)

    Naab, Laurie; Henry, David

    2009-01-01

    Using Wiggins and McTighe's (1998) concept of Big Ideas, the authors planned and designed an electricity investigation to address common student misconceptions about static electricity. With Styrofoam plates and transparent tape, elementary students investigated many properties of electrically charged and uncharged objects in a 5E learning cycle…

  15. 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...

  16. Static Gravitational Global Monopoles

    CERN Document Server

    Liebling, S L

    2000-01-01

    Static solutions in spherical symmetry are found for gravitating global monopoles. Regular solutions lacking a horizon are found for $\\eta \\sqrt{3/8\\pi} \\approx 0.3455$ is consistent with findings that topological inflation begins at $\\eta \\approx 0.33$.

  17. Discussion on the ore-controlling factors and metallogenesis of Yanshan Au, Ag, Pb, Zn deposits in the volcanic rock of Southeastern Zhejiang%浙东南火山岩地区燕山期金银铅锌矿床控矿因素及成因探讨

    Institute of Scientific and Technical Information of China (English)

    何元才; 俞跃平

    2011-01-01

    Based on the study of ore - controlling factors and metallogenesis, it was concluded in this paper that the Au, Ag, Pb, Zn deposits related to Yanshan volcanic rock in Southeastern Zhejiang were meso - epithemal deposits, and the hydrothermal fluid was originated from rainwater, and ore - forming materials were derived from wall rock as well. So water source and heat source were the key factors in the ore - forming process. Water played a special effect on the ore - forming process and deposits distributed because of continental margin of volcanic activities. It was concluded that water - bearing faulted structure and sedimentary formation were the optimistical section for large - scale deposit.%文章对浙东南火山岩地区燕山期金银铅锌矿床的控矿因素和成因进行了分析研究,认为浙东南燕山期金银铅锌矿属于浅成中低温热液矿床,其热液来源于雨水,成矿物质来源于围岩,水源和热源在成矿过程中起着决定性的作用,陆缘火山活动的地质背景决定了水在成矿作用中的特殊作用,决定了矿床的空间分布,含水的断裂构造和沉积建造是寻找大型矿床的最有利地段.

  18. 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.

  19. The Static Quantum Multiverse

    OpenAIRE

    Nomura, Yasunori

    2012-01-01

    We consider the multiverse in the intrinsically quantum mechanical framework recently proposed in Refs. [1,2]. By requiring that the principles of quantum mechanics are universally valid and that physical predictions do not depend on the reference frame one chooses to describe the multiverse, we find that the multiverse state must be static---in particular, the multiverse does not have a beginning or end. We argue that, despite its naive appearance, this does not contradict observation, inclu...

  20. Open static Chaplygin universe

    CERN Document Server

    Khalatnikov, I M

    2003-01-01

    We apply the qualitative theory of dynamical systems to the study of the Chaplygin gas cosmological model. In difference to earlier works devoted to this model we give up sign restrictions on the choice of the sign of the energy density and on the parameters characterising initial conditions for a cosmological evolution. It appears that exists a static stable open universe filled with the Chaplygin gas. Besides exist universes where the acoustic waves have a velocity exceeding that of light in the vacuum.

  1. 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....

  2. Model Checking as Static Analysis

    DEFF Research Database (Denmark)

    Zhang, Fuyuan

    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...... 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......-calculus can be encoded as the intended model of SFP. Our research results have strengthened the link between model checking and static analysis. This provides a theoretical foundation for developing a unied tool for both model checking and static analysis techniques....

  3. 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.

  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. Diffuse scattering measurements of static atomic displacements in crystalline binary solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ice, G.E.; Sparks, C.J.; Jiang, X.; Robertson, L.

    1997-09-01

    Diffuse x-ray scattering from crystalline solid solutions is sensitive to both local chemical order and local bond distances. In short-range ordered alloys, fluctuations of chemistry and bond distances break the long-range symmetry of the crystal within a local region and contribute to the total energy of the alloy. Recent use of tunable synchrotron radiation to change the x-ray scattering contrast between elements has greatly advanced the measurement of bond distances between the three kinds of atom pairs found in crystalline binary alloys. The estimated standard deviation on these recovered static displacements approaches {+-}0.001 {angstrom} (0.0001 nm) which is an order of magnitude more precise than obtained with EXAFS. In addition, both the radial and tangential displacements can be recovered to five near neighbors and beyond. These static displacement measurements provide new information which challenges the most advanced theoretical models of binary crystalline alloys. 29 refs., 8 figs., 2 tabs.

  6. 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.

  7. Static intervortex forces

    Science.gov (United States)

    Speight, J. M.

    1997-03-01

    A point particle approximation to the classical dynamics of well-separated vortices of the Abelian Higgs model is developed. A static vortex is asymptotically identical to a solution of the linearized field theory (a Klein-Gordon-Proca theory) in the presence of a singular point source at the vortex center. It is shown that this source is a composite scalar monopole and magnetic dipole, and the respective charges are determined numerically for various values of the coupling constant. The interaction potential of two well-separated vortices is computed by calculating the interaction Lagrangian of two such point sources in the linear theory. The potential is used to model type II vortex scattering.

  8. 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...

  9. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  10. STATIC RECRYSTALLIZATION AFTER HOT WORKING OF Al-Li ALLOYS

    OpenAIRE

    Gonçalves, M.; Sellars, C

    1987-01-01

    Small slabs of DC cast and homogenised 8090 and 8091 have been hot rolled in an experimental mill at temperatures in the range 300-500°C and subsequently solution treated at 550°C for times up to 48 hrs. Increase in rolling temperature leads to slower recrystallization, but the effect diminishes at long solution treatment times when the rolling temperature is above 400°C. Recrystallized grains are nearly equiaxed after rolling at temperatures below 400°C but are elongated after rolling at hig...

  11. Aluminum alloy

    Science.gov (United States)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  12. Static recrystallization behavior of a martensitic heat-resistant stainless steel 403Nb

    Institute of Scientific and Technical Information of China (English)

    Zhouyu ZENG; Liqing CHEN; Fuxian ZHU; Xianghua LIU

    2011-01-01

    A static recrystallization behavior between the rolling passes of a martensitic heatresistant stainless steel 403Nb has been studied by OM,TEM and double-hit thermomechanical simulator to explore the effects of deformation temperature,strain rate,strain and the prior austenite grain size.The results show that increases of deformation temperature and strain rate and strain can promote the static recrystallization of 403Nb steel.Static recrystallization also proceeds faster when the prior austenite grain size is smaller.Microstructural observation indicates that the volume fraction of static recrystallization increases with prolonged interval of the rolling passes.Straininduced precipitation can lead to an appearance of a platform in the kinetic curve of static recrystallization.Different from the conventional micro-alloying steel,the strain-induced precipitates in 403Nb steel during hot rolling are carbides containing Nb and Cr.

  13. Metal and alloy nanoparticles by amine-borane reduction of metal salts by solid-phase synthesis: atom economy and green process.

    Science.gov (United States)

    Sanyal, Udishnu; Jagirdar, Balaji R

    2012-12-03

    A new solid state synthetic route has been developed toward metal and bimetallic alloy nanoparticles from metal salts employing amine-boranes as the reducing agent. During the reduction, amine-borane plays a dual role: acts as a reducing agent and reduces the metal salts to their elemental form and simultaneously generates a stabilizing agent in situ which controls the growth of the particles and stabilizes them in the nanosize regime. Employing different amine-boranes with differing reducing ability (ammonia borane (AB), dimethylamine borane (DMAB), and triethylamine borane (TMAB)) was found to have a profound effect on the particle size and the size distribution. Usage of AB as the reducing agent provided the smallest possible size with best size distribution. Employment of TMAB also afforded similar results; however, when DMAB was used as the reducing agent it resulted in larger sized nanoparticles that are polydisperse too. In the AB mediated reduction, BNH(x) polymer generated in situ acts as a capping agent whereas, the complexing amine of the other amine-boranes (DMAB and TMAB) play the same role. Employing the solid state route described herein, monometallic Au, Ag, Cu, Pd, and Ir and bimetallic CuAg and CuAu alloy nanoparticles of <10 nm were successfully prepared. Nucleation and growth processes that control the size and the size distribution of the resulting nanoparticles have been elucidated in these systems.

  14. Surface Compositional Characteristics of Au/Ag Alloy Nanoparticles Revealed by Surface-enhanced Raman Scattering of Aromatic Isocyanides%芳香异腈的SERS光谱所揭示的金/银纳米颗粒阵列的表面组分特性

    Institute of Scientific and Technical Information of China (English)

    Hyoung; Kun; Park; Kwan; Kim

    2005-01-01

    @@ A major task in molecular electronics is the precise determination of the molecule-metal interface characteristics. This is particularly because metals and single molecules have intrinsically unavoidable electrical mismatches but there is not yet an established way to evaluate them systematically.

  15. Static Validation of XSL Transformations

    DEFF Research Database (Denmark)

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

    2007-01-01

    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 languages....... Our analysis takes a pragmatic approach that focuses its precision on the essential language features but still handles the entire XSLT language. We evaluate the analysis precision on a range of real stylesheets and demonstrate how it may be useful in practice....

  16. 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.

  17. Static and Dynamic Traversable Wormholes

    Science.gov (United States)

    Adamiak, Jaroslaw P.

    2008-09-01

    The aim of this work is to discuss the effects found in static and dynamic wormholes that occur as a solution of Einstein equations in general relativity. The ground is prepared by presentation of faster than light effects, then the focus is narrowed to Morris-Thorne framework for a static spherically symmetric wormhole. Two types of dynamic worm-holes, evolving and rotating, are considered.

  18. 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...

  19. Static Filtered Sky Color Constancy

    Directory of Open Access Journals (Sweden)

    Ali Alkhalifah

    2016-05-01

    Full Text Available In Computer Vision, the sky color is used for lighting correction, image color enhancement, horizon alignment, image indexing, and outdoor image classification and in many other applications. In this article, for robust color based sky segmentation and detection, usage of lighting correction for sky color detection is investigated. As such, the impact of color constancy on sky color detection algorithms is evaluated and investigated. The color correction (constancy algorithms used includes Gray-Edge (GE, Gray-World (GW, Max-RGB (MRGB and Shades-of-Gray (SG. The algorithms GE, GW, MRGB, and SG, are tested on the static filtered sky modeling. The static filter is developed in the LAB color space. This evaluation and analysis is essential for detection scenarios, especially, color based object detection in outdoor scenes. From the results, it is concluded that the color constancy before sky color detection using LAB static filters has the potential of improving sky color detection performance. However, the application of the color constancy can impart adverse effects on the detection results. For images, the color constancy algorithms depict a compact and stable representative of the sky chroma loci, however, the sky color locus might have a shifting and deviation in a particular color representation. Since the sky static filters are using the static chromatic values, different results can be obtained by applying color constancy algorithms on various datasets.

  20. Formation Epoch of the South Tiegelong Supelarge Epithermal Cu (Au-Ag) Deposit in Tibet and Its Geological Implications%西藏铁格隆南超大型浅成低温热液铜(金、银)矿床的形成时代及其地质意义

    Institute of Scientific and Technical Information of China (English)

    方向; 卫鲁杰; 张志; 杨欢欢; 高轲; 唐攀; 唐菊兴; 宋杨; 杨超; 丁帅; 王艺云; 王勤; 孙兴国; 李玉彬

    2015-01-01

    铁格隆南(荣那)矿床位于西藏班公湖—怒江成矿带西段的多龙整装勘查区内,是西藏首例超大规模的浅成低温热液-斑岩型Cu(Au、Ag)矿床。目前,矿床的勘查工作和科学研究正同时展开,本文采用锆石U-Pb、辉钼矿 Re-Os 同位素定年技术,结合系统的钻孔地质编录,对编录中新发现的含矿石英闪长玢岩和辉钼矿进行了高精度同位素测年。石英闪长玢岩LA-ICP-MS锆石U-Pb模式年龄为(120.2±1.0) Ma;辉钼矿Re-Os同位素测年的模式年龄分布在117.8~119.4 Ma范围内,平均模式年龄为(118.5±0.8) Ma,等时线年龄为(119.0±1.4) Ma(MSWD=0.34)。成岩成矿年龄近于一致,成矿略晚于成岩年龄,表明二者属于同一斑岩-浅成低温热液成矿系统。辉钼矿187Re 的含量分布于230.47~1226.6μg/g,指示成矿物质具幔源特征,暗示铁格隆南巨量金属物质的聚集可能与壳幔边界岩浆作用有关。对比研究表明,铁格隆南成矿作用与多不杂、波龙铜(金)矿床一同受控于统一的构造-岩浆成矿系统,该系统的形成无疑与早白垩世班公湖—怒江洋盆向北俯冲有关。%The South Tiegelong (Rongna) deposit, the first superlarge epithermal porphyry Cu (Au, Ag) deposit discovered in Tibet, is situated in the Duolong ore district along the west segment of the Bangong Co–Nujiang River metallogenic belt of Tibet. Both the exploration work and the scientific study of this deposit are being carried out at present. In combination with scientific geological logging, the authors applied the zircon U-Pb and molybdenite Re-Os isotopic dating to the newly found mineral-bearing quartz diorite porphyry and molybdenite. The LA-ICP-MS zircon U-Pb dating of the porphyry yielded a petrogenic age of (120.2±1.0) Ma, and the Re-Os isotopic model ages of molybdenite are distributed in the range of 117.8~119.4 Ma, which vary limitedly with an average model age of (118.45±0.76) Ma. The Re-Os isochron age

  1. Evolving Density and Static Mechanical Properties in Plutonium from Self-Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chung, B W; Thompson, S R; Lema, K E; Hiromoto, D S; Ebbinghaus, B B

    2008-07-31

    Plutonium, because of its self-irradiation by alpha decay, ages by means of lattice damage and helium in-growth. These integrated aging effects result in microstructural and physical property changes. Because these effects would normally require decades to measure, studies are underway to assess the effects of extended aging on the physical properties of plutonium alloys by incorporating roughly 7.5 weight % of highly specific activity isotope {sup 238}Pu into the {sup 239}Pu metal to accelerate the aging process. This paper presents updated results of self-irradiation effects on {sup 238}Pu-enriched alloys measured by immersion density, dilatometry, and tensile tests. After nearly 90 equivalent years of aging, both the immersion density and dilatometry show that the enriched alloys continue to decreased in density by {approx}0.002% per year, without void swelling. Quasi-static tensile measurements show that the aging process increases the strength of plutonium alloys.

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

    Science.gov (United States)

    Hulse, C. O.; Bailey, R. S.; Grant, H. P.; Przybyszewski, J. S.

    1987-07-01

    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.

  3. Static-Fluid Black Holes

    CERN Document Server

    Cho, Inyong

    2016-01-01

    We investigate black holes formed by static perfect fluid with $p=-\\rho/3$. These represent the black holes in $S_3$ and $H_3$ spatial geometries. There are three classes of black-hole solutions, two $S_3$ types and one $H_3$ type. The interesting solution is the one of $S_3$ type which possesses two singularities. The one is at the north pole behind the horizon, and the other is naked at the south pole. The observers, however, are free from falling to the naked singularity. There are also nonstatic cosmological solutions in $S_3$ and $H_3$, and a singular static solution in $H_3$.

  4. Static Fourier transform infrared spectrometer.

    Science.gov (United States)

    Schardt, Michael; Murr, Patrik J; Rauscher, Markus S; Tremmel, Anton J; Wiesent, Benjamin R; Koch, Alexander W

    2016-04-01

    Fourier transform spectroscopy has established itself as the standard method for spectral analysis of infrared light. Here we present a robust and compact novel static Fourier transform spectrometer design without any moving parts. The design is well suited for measurements in the infrared as it works with extended light sources independent of their size. The design is experimentally evaluated in the mid-infrared wavelength region between 7.2 μm and 16 μm. Due to its large etendue, its low internal light loss, and its static design it enables high speed spectral analysis in the mid-infrared.

  5. 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....

  6. 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.

  7. Casting of MOD inlay using rings with holes on both sides: 12∼18 wt%Au-20∼26Pd-14.48∼26.48Cu-40Ag-1.5Zn-0.02Ir alloys.

    Science.gov (United States)

    Ohkuma, Kazuo; Kazama, Miku; Ogura, Hideo

    2012-01-01

    Using a casting ring with openings on both sides and a water-absorbent polymer, heterogeneity is maintained in a single casting and a precise MOD inlay can be produced. We produced 9 different kinds of gold-silver-palladium (Au-Ag-Pd) alloys by changing the ratio of palladium, gold, and copper and investing them, and changing parameters such as the angulation of the casting ring openings and the water:powder ratios to produce MOD inlay castings. We measured the expansion and shrinkage percentage of the castings in both the buccolingual and mesiodistal directions. From this experiment, we learned that precise MOD inlay castings can be produced using rings with 240° openings when invested in a thick mix having a standard water:powder ratio or using rings with 200° openings when invested in a thick mix having a water:powder ratio for a 12 wt%Au-20∼26Pd-20.48∼26.48Cu-40Ag-1.5Zn-0.02Ir alloyes.

  8. 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.

  9. Plastic Instabilities and Their Consequences in Steels and Other High Strength Alloys

    Science.gov (United States)

    1991-09-01

    rate yes Superalloys * Alloy 600 quasi-static no Rend 41 quasi-static no Steels * HY80 quasi-static no ultra-soft5 no low temperatures no AISI 4340...AD-A240 976 ([f) A Final Technical Report Contract No. N00014-88-K-0111 S PLASTIC INSTABILITIES AND THEIR CONSEQUENCES IN STEELS AND OTHER HIGH...PLASTIC INSTABILITIES AND THEIR CONSEQUENCES IN STEELS AND OTHER HIGH STRENGTH ALLOYS Submitted to: Office of Naval Research 800 North Quincy Street

  10. Compatibility of ITER candidate structural materials with static gallium

    Energy Technology Data Exchange (ETDEWEB)

    Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

    1993-12-01

    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 {approx}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 {ge}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.

  11. 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 foundations...... theory is proposed. The proposed expression applies to plane strain as well as axis-symmetric stress conditions for foundations with smooth or rough bases. A thorough experimental investigation of the static behaviour of bucket foundations subjected to combined loading is carried out. Laboratory tests...... method is concluded to be a superior method in estimating the post peak behaviour as well as the combined capacity of bucket foundations in relation to the offshore wind turbine problem....

  12. 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.

  13. Static Analysis of Dynamic Languages

    DEFF Research Database (Denmark)

    Madsen, Magnus

    on the behaviour of these languages. A common theme is the reliance on static program analysis to over-approximate the behaviour of programs written in these languages. Specifically, the use of whole-program dataflow analysis. The research challenge of this line of work is the adaption of existing- and invention......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...

  14. 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...

  15. High temperature static strain gage development

    Science.gov (United States)

    Hulse, C. O.; Bailey, R. S.; Grant, H. P.; Anderson, W. L.; Przybyszewski, J. S.

    1991-01-01

    Final results are presented from a program to develop a thin film static strain gage for use on the blades and vanes of running, test stand gas turbine engines with goals of an 3 x 3 mm gage area and total errors of less than 10 pct. of + or - 2,000 microstrain after 50 hrs at 1250 K. Pd containing 13 Wt. pct. Cr was previously identified as a new strain sensor alloy that appeared to be potentially usable to 1250 K. Subsequently, it was discovered, in contrast with its behavior in bulk, that Pd-13Cr suffered from oxidation attack when prepared as a 4.5 micron thick thin film. Continuing problems with electrical leakage to the substrate and the inability of sputtered alumina overcoats to prevent oxidation led to the discovery that sputtered alumina contains appreciable amounts of entrapped argon. After the argon has been exsolved by heating to elevated temperatures, the alumina films undergo a linear shrinkage of about 2 pct. resulting in formation of cracks. These problems can be largely overcome by sputtering the alumina with the substrate heated to 870 K. With 2 micron thick hot sputtered alumina insulation and overcoat films, total 50 hr drifts of about 100 microstrain (2 tests) and about 500 microstrain (1 test) were observed at 1000 and 1100 K, respectively. Results of tests on complete strain gage systems on constant moment bend bars with Pd temperature compensation grids revealed that oxidation of the Pd grid was a major problem even when the grid was overcoated with a hot or cold sputtered alumina overcoat.

  16. In-Flight Pitot-Static Calibration

    Science.gov (United States)

    Foster, John V. (Inventor); Cunningham, Kevin (Inventor)

    2016-01-01

    A GPS-based pitot-static calibration system uses global output-error optimization. High data rate measurements of static and total pressure, ambient air conditions, and GPS-based ground speed measurements are used to compute pitot-static pressure errors over a range of airspeed. System identification methods rapidly compute optimal pressure error models with defined confidence intervals.

  17. 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....

  18. 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.

  19. Design and Fem Analysis of Car Alloy Wheel

    Directory of Open Access Journals (Sweden)

    Venkatesh. K

    2016-12-01

    Full Text Available The requirements for improved stiffness, reliability, fatigue life and increased efficiency involves challenges of developing innovative design solutions. The present work mainly focus on the design of car alloy wheel, where the analytical and FEM analysis approach was implemented to analyze baseline design. Initially static analysis was performed to obtain total deformation, strain and the stress of car alloy wheel. Three Dimensional model was created using CATIA and FE software ANSYS was used for discretization and analysis to obtain expected solution. The results were obtained through linear static analysis in terms of Total deformation while Minimum principal stress, Max Principal stress were found to be nearly equal for both 6 arms wheel and 4 arms wheel and 22.16 % of reduction in weight was observed and hence overall weight of the car alloy wheel was optimized.

  20. Static Validation of Security Protocols

    DEFF Research Database (Denmark)

    Bodei, Chiara; Buchholtz, Mikael; Degano, P.;

    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. Static Charge Development on Explosives .

    Directory of Open Access Journals (Sweden)

    K. Raha

    1991-01-01

    Full Text Available Static charge development character of some of the important explosive crystals have been predicted on the basis of their crystal class and symmetry. Among the important mechanism of charge development, the piezoelectric and pyroelectric characters have been considered. Ammonium trinitrate, ammonium nitrate, m-dinitro-benzene, trinitro-toluene, styphnic acid, beeta-lead styphnate, 4,4'dinitro-dipheny1, a-hexamethylenetetranitramine, nitroguanidine, picric acid, dimethylnitramine, a-lead azide and beeta-lead azide are pyroelectric in nature, whereas pentaerythritol tetranitrate, picryliodide, hexamethylenetranitramine, tetranitromethane and trinitroethane are piezoelectric in nature.

  2. Static Analysis for Dynamic XML

    DEFF Research Database (Denmark)

    Christensen, Aske Simon; Møller, Anders; Schwartzbach, Michael Ignatieff

    2002-01-01

    We describe the summary graph lattice for dataflow analysis of programs that dynamically construct XML documents. Summary graphs have successfully been used to provide static guarantees in the JWIG language for programming interactive Web services. In particular, the JWIG compiler is able to check...... validity of dynamically generated XHTML documents and to type check dynamic form data. In this paper we present summary graphs and indicate their applicability for various scenarios. We also show that the expressive power of summary graphs is similar to that of the regular expression types from XDuce......, but that the extra structure in summary graphs makes them more suitable for certain program analyses....

  3. A Simplified Test for Blanching Susceptibility of Copper Alloys

    Science.gov (United States)

    Thomas-Ogbuji, Linus U.; Humphrey, Donald; Setlock, John

    2003-01-01

    GRCop-84 (Cu-8Cr-4Nb) is a dispersion-strengthened alloy developed for space-launch rocket engine applications, as a liner for the combustion chamber and nozzle ramp. Its main advantage over rival alloys, particularly NARloy-Z (Cu-Ag-Zr), the current liner alloy, is in high temperature mechanical properties. Further validation required that the two alloys be compared with respect to service performance and durability. This has been done, under conditions resembling those expected in reusable launch engine applications. GRCop-84 was found to have a superior resistance to static and cyclic oxidation up to approx. 700 C. In order to improve its performance above 700 C, Cu-Cr coatings have also been developed and evaluated. The major oxidative issue with Cu alloys is blanching, a mode of degradation induced by oxidation-reduction fluctuations in hydrogen-fueled engines. That fluctuation cannot be addressed with conventional static or cyclic oxidation testing. Hence, a further evaluation of the alloy substrates and Cu-Cr coating material necessitated our devising a test protocol that involves oxidaton-reduction cycles. This paper describes the test protocols used and the results obtained.

  4. Fracture characteristics of structural aerospace alloys containing deep surface flaws. [aluminum-titanium alloys

    Science.gov (United States)

    Masters, J. N.; Bixler, W. D.; Finger, R. W.

    1973-01-01

    Conditions controlling the growth and fracture of deep surface flaws in aerospace alloys were investigated. Static fracture tests were performed on 7075-T651 and 2219-T87 aluminum, and 6Ai-4V STA titanium . Cyclic flaw growth tests were performed on the two latter alloys, and sustain load tests were performed on the titanium alloy. Both the cyclic and the sustain load tests were performed with and without a prior proof overload cycle to investigate possible growth retardation effects. Variables included in all test series were thickness, flaw depth-to-thickness ratio, and flaw shape. Results were analyzed and compared with previously developed data to determine the limits of applicability of available modified linear elastic fracture solutions.

  5. Electrowetting -- from statics to dynamics.

    Science.gov (United States)

    Chen, Longquan; Bonaccurso, Elmar

    2014-08-01

    More than one century ago, Lippmann found that capillary forces can be effectively controlled by external electrostatic forces. As a simple example, by applying a voltage between a conducting liquid droplet and the surface it is sitting on we are able to adjust the wetting angle of the drop. Since Lippmann's findings, electrocapillary phenomena - or electrowetting - have developed into a series of tools for manipulating microdroplets on solid surfaces, or small amounts of liquids in capillaries for microfluidic applications. In this article, we briefly review some recent progress of fundamental understanding of electrowetting and address some still unsolved issues. Specifically, we focus on static and dynamic electrowetting. In static electrowetting, we discuss some basic phenomena found in DC and AC electrowetting, and some theories about the origin of contact angle saturation. In dynamic electrowetting, we introduce some studies about this rather recent area. At last, we address some other capillary phenomena governed by electrostatics and we give an outlook that might stimulate further investigations on electrowetting.

  6. COMPUTER NUMERICAL SIMULATION OF MECHANICAL PROPERTIES OF TUNGSTEN HEAVY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A microstructure model of tungsten heavy alloys has been developed. On the basis of the model and several assumptions, the macro-mechanical properties of 90 W heavy alloy under quasi-static tensile deformation and the effects of microstructural parameters (mechanical properties of the matrix phase and tungsten content) on them have been analyzed by computer numerical simulation. The mechanical properties of the alloy have been found to be dependent on the mechanical parameters of the matrix phase. As the elastic modulus and yield strength of the matrix phase increase, the tensile strength of the alloy increases, while the elongation decreases. If the mechanical parameters except the tensile strength of the matrix phase are constant, both the tensile strength and the elongation of the alloy increase linearly with the increase of tensile strength of the matrix phase. The properties of the alloy are very sensitive to the hardening modulus of the matrix phase. As the hardening modulus increases, both the tensile strength and the elongation of the alloy exponentially decrease. The elongation of the alloys monotonically decreases with the increase of tungsten content, while the decrease of tensile strength is not monotonic. When the tungsten content < 85 %, the strength of tungsten heavy alloys increases with the increase of tungsten content, while decreases when the tungsten content >85 %. The maximum of tensile strength of the alloys appears at the tungsten content of 85 %. The results showed that the binder phase with a higher strength and a lower hardening modulus is advantageous to obtaining an optimum combination of mechanical properties of tungsten heavy alloys.

  7. 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.

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

    Science.gov (United States)

    Latif, Kesemen; Kaan, Çalışkan N.; Emrah, Konokman H.; Nuri, Durlu

    2015-09-01

    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.

  9. Thin-film diffusion brazing of titanium alloys

    Science.gov (United States)

    Mikus, E. B.

    1972-01-01

    A thin film diffusion brazing technique for joining titanium alloys by use of a Cu intermediate is described. The method has been characterized in terms of static and dynamic mechanical properties on Ti-6Al-4V alloy. These include tensile, fracture toughness, stress corrosion, shear, corrosion fatigue, mechanical fatigue and acoustic fatigue. Most of the properties of titanium joints formed by thin film diffusion brazing are equal or exceed base metal properties. The advantages of thin film diffusion brazing over solid state diffusion bonding and brazing with conventional braze alloys are discussed. The producibility advantages of this process over others provide the potential for producing high efficiency joints in structural components of titanium alloys for the minimum cost.

  10. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    . Traditionally, theorem provers are used to prove that specifications are correct but this process is highly dependent on expert users. Alternatively, model finding has proved to be useful for validation of specifications. The Alloy Analyzer is an automated model finder for checking and visualising Alloy...... 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...

  11. 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.

  12. Reduction in static friction by deposition of a homogeneous diamond-like carbon (DLC) coating on orthodontic brackets.

    Science.gov (United States)

    Akaike, Shun; Hayakawa, Tohru; Kobayashi, Daishiro; Aono, Yuko; Hirata, Atsushi; Hiratsuka, Masanori; Nakamura, Yoshiki

    2015-01-01

    In orthodontics, a reduction in static friction between the brackets and wire is important to enable easy tooth movement. The aim of this study was to examine the effects of a homogeneous diamond-like carbon (DLC) coating on the whole surfaces of slots in stainless steel orthodontic brackets on reducing the static friction between the brackets and the wire. The DLC coating was characterized using Raman spectroscopy, surface roughness and contact angle measurements, and SEM observations. Rectangular stainless steel and titanium-molybdenum alloy wires with two different sizes were employed, and the static friction between the brackets and wire was measured under dry and wet conditions. The DLC coating had a thickness of approximately 1.0 μm and an amorphous structure was identified. The results indicated that the DLC coating always led to a reduction in static friction.

  13. A study on a dental device for the prevention of mucosal dose enhancement caused by backscatter radiation from dental alloy during external beam radiotherapy.

    Science.gov (United States)

    Katsura, Kouji; Utsunomiya, Satoru; Abe, Eisuke; Sakai, Hironori; Kushima, Naotaka; Tanabe, Satoshi; Yamada, Takumi; Hayakawa, Takahide; Yamanoi, Yoshihiko; Kimura, Syuhei; Wada, Shinichi; Aoyama, Hidefumi; Hayashi, Takafumi

    2016-11-01

    The changes in dose distribution caused by backscatter radiation from a common commercial dental alloy (Au-Ag-Pd dental alloy; DA) were investigated to identify the optimal material and thicknesses of a dental device (DD) for effective prevention of mucositis. To this end, 1 cm(3) of DA was irradiated with a 6-MV X-ray beam (100 MU) in a field size of 10 × 10 cm(2) using a Novalis TX linear accelerator. Ethylene vinyl acetate copolymer, polyolefin elastomer, and polyethylene terephthalate (PET) were selected as DD materials. The depth dose along the central axis was determined with respect to the presence/absence of DA and DDs at thicknesses of 1-10 mm using a parallel-plate ionization chamber. The dose in the absence of DDs showed the lowest value at a distance of 5 mm from the DA surface and gradually increased with distance between the measurement point and the DA surface for distances of ≥5 mm. Except for PET, no significant difference between the DA dose curves for the presence and absence of DDs was observed. In the dose curve, PET showed a slightly higher dose for DA with DD than for DA without DD for thicknesses of ≥4 mm. The findings herein suggest that the optimal DD material for preventing local dose enhancement of the mucosa caused by DA backscatter radiation should have a relatively low atomic number and physical density and that optimal DD thickness should be chosen considering backscatter radiation and percentage depth dose.

  14. 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...

  15. Static and non-static black holes with the Liouville mode

    Science.gov (United States)

    Moskalets, T. M.; Nurmagambetov, A. J.

    2017-03-01

    We present a new class of static and non-static quasi-spherical black hole solutions in four-dimensional Minkowski and Anti-de Sitter spaces and briefly discuss its employing in the Gauge/Gravity duality.

  16. 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...

  17. PLUTONIUM-THORIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  18. 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.

  19. Static balance and developmental coordination disorder

    NARCIS (Netherlands)

    Geuze, RH

    2003-01-01

    The development of static balance is a basic characteristic of normal motor development. Most of the developmental motor tests include a measure of static balance. Children with a developmental coordination disorder (DCD) often fail this item. Twenty-four children at risk for DCD with balance proble

  20. Static Complexity Analysis of Higher Order Programs

    DEFF Research Database (Denmark)

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

    2009-01-01

    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....

  1. Model Checking as Static Analysis: Revisited

    DEFF Research Database (Denmark)

    Zhang, Fuyuan; Nielson, Flemming; Nielson, Hanne Riis

    2012-01-01

    We show that the model checking problem of the μ-calculus can be viewed as an instance of static analysis. We propose Succinct Fixed Point Logic (SFP) within our logical approach to static analysis as an extension of Alternation-free Least Fixed Logic (ALFP). We generalize the notion...

  2. Static domain wall in braneworld gravity

    Energy Technology Data Exchange (ETDEWEB)

    Abdalla, M.C.B.; Carlesso, P.F. [UNESP, Universidade Estadual Paulista, Instituto de Fisica Teiorica, Rua Dr. Bento Teobaldo Ferraz 271, Bloco II, Barra-Funda, Caixa Postal 70532-2, Sao Paulo, SP (Brazil); Hoff da Silva, J.M. [UNESP, Universidade Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil)

    2014-01-15

    In this paper we consider a static domain wall inside a 3-brane. Different from the standard achievement obtained in General Relativity, the analysis performed here gives a consistency condition for the existence of static domain walls in a braneworld gravitational scenario. Also the behavior of the domain wall's gravitational field in the newtonian limit is shown. (orig.)

  3. 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.

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

    Science.gov (United States)

    Barrett, C. A.; Titran, R. H.

    1992-01-01

    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.

  5. 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.

  6. High strength alloys

    Science.gov (United States)

    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. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  8. 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.)

  9. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  10. Aftershocks halted by static stress shadows

    Science.gov (United States)

    Toda, Shinji; Stein, Ross S.; Beroza, Gregory C.; Marsan, David

    2012-06-01

    Earthquakes impart static and dynamic stress changes to the surrounding crust. Sudden fault slip causes small but permanent--static--stress changes, and passing seismic waves cause large, but brief and oscillatory--dynamic--stress changes. Because both static and dynamic stresses can trigger earthquakes within several rupture dimensions of a mainshock, it has proven difficult to disentangle their contributions to the triggering process. However, only dynamic stress can trigger earthquakes far from the source, and only static stress can create stress shadows, where the stress and thus the seismicity rate in the shadow area drops following an earthquake. Here we calculate the stress imparted by the magnitude 6.1 Joshua Tree and nearby magnitude 7.3 Landers earthquakes that occurred in California in April and June 1992, respectively, and measure seismicity through time. We show that, where the aftershock zone of the first earthquake was subjected to a static stress increase from the second, the seismicity rate jumped. In contrast, where the aftershock zone of the first earthquake fell under the stress shadow of the second and static stress dropped, seismicity shut down. The arrest of seismicity implies that static stress is a requisite element of spatial clustering of large earthquakes and should be a constituent of hazard assessment.

  11. Static and Dynamic Mechanics Analysis on Artificial Hip Joints with Different Interface Designs by the Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    Hai-bo Jiang

    2007-01-01

    Four different structural models of artificial joints were developed and the finite element method (FEM) was employed to investigate their mechanical characteristics under static and dynamic conditions. The materials used in the FEM calculation were ultra-high molecular weight polyethylene (UHMWPE), 316L stainless steel, CoCrMo alloy and Ti6A14V alloy. The stress distribution, strain, and elastic deformation under static and dynamic conditions were obtained. Analysis and comparison of the calculation results of different models were conducted. It is shown that with the same parameters the model of a metallic femur head covered with an artificial cartilage layer is more similar to the structure of the natural human joint and its mechanical characteristics are the best of the four models.

  12. Pheromone Static Routing Strategy for Complex Networks

    CERN Document Server

    Ling, Xiang; Jiang, Rui; Hu, Mao-Bin

    2011-01-01

    In this paper, we adopt the concept of pheromone to generate a set of static paths that can reach the performance of global dynamic routing strategy [Phys. Rev. E 81, 016113(2010)]. In the test stage, pheromone is dropped to the nodes by packets forwarded by the global dynamic routing strategy. After that, static paths are generated according to the density of pheromone. The output paths can greatly improve traffic systems' overall capacity on different network structures, including scale-free networks, small-world networks and random graphs. Because the paths are static, the system needs much less computational resource than the global dynamic routing strategy.

  13. 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.

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

    Science.gov (United States)

    Liu, Bing; Chen, Da-Rong; Chen, Zheng; Wang, Yong-Xin; Li, Xiao-Ling

    2003-11-01

    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.

  16. On static equilibrium and balance puzzler

    CERN Document Server

    Dey, Samrat; Saikia, Dipankar; Kalita, Deepjyoti; Debbarma, Anamika; Wahab, Shaheen Akhtar; Sarma, Saurabh

    2012-01-01

    The principles of static equilibrium are of special interest to civil engineers. For a rigid body to be in static equilibrium the condition is that net force and net torque acting on the body should be zero. That clearly signifies that if equal weights are placed on either sides of a balance, the balance should be in equilibrium, even if its beam is not horizontal (we have considered the beam to be straight and have no thickness, an ideal case). Thus, although the weights are equal, they will appear different which is puzzling. This also shows that the concept of equilibrium is confusing, especially neutral equilibrium is confused to be stable equilibrium. The study not only throws more light on the concept of static equilibrium, but also clarifies that a structure need not be firm and steady even if it is in static equilibrium.

  17. 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...

  18. Analytic three-loop static potential

    Science.gov (United States)

    Lee, Roman N.; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

    2016-09-01

    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.

  19. Static Stress Analysis of Security Injection Tank

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The static structural analysis of the security injection tank is made to make sure whether the tank can withstand concerned loads or not on all conditions conforming to concerned code prescripts and design requirements. The tanks

  20. Typification of Statice dichotoma Cav. (Plumbaginaceae

    Directory of Open Access Journals (Sweden)

    Ferrer-Gallego, P. Pablo

    2013-12-01

    Full Text Available A lectotype and an epitype are here designated for Statice dichotoma Cav. (Plumbaginaceae, an endemic taxon from the central part of the Iberian Peninsula, which is currently named Limonium dichotomum (Cav. KuntzeSe designan un lectótipo y un epítipo para Statice dichotoma Cav. (Plumbaginaceae, un taxon endémico del centro de la península Ibérica, actualmente denominado Limonium dichotomum (Cav. Kuntze.

  1. Statics formulas and problems : engineering mechanics 1

    CERN Document Server

    Gross, Dietmar; Wriggers, Peter; Schröder, Jörg; Müller, Ralf

    2017-01-01

    This book contains the most important formulas and more than 160 completely solved problems from Statics. It provides engineering students material to improve their skills and helps to gain experience in solving engineering problems. Particular emphasis is placed on finding the solution path and formulating the basic equations. Topics include: - Equilibrium - Center of Gravity, Center of Mass, Centroids - Support Reactions - Trusses - Beams, Frames, Arches - Cables - Work and Potential Energy - Static and Kinetic Friction - Moments of Inertia.

  2. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  3. Petrogenetic setting of andsites in Rongna ore block, Tiegelong Cu (Au-Ag) deposit, Duolong ore concentration area, Tibet:Evidence from zircon U-Pb LA-ICP-MS dating and petrogeochemistry of andsites%西藏多龙矿集区铁格隆南铜(金银)矿床荣那矿段安山岩成岩背景:来自锆石U-Pb年代学、岩石地球化学的证据

    Institute of Scientific and Technical Information of China (English)

    王勤; 卫鲁杰; 冯军; 李力; 唐菊兴; 方向; 林彬; 宋扬; 王艺云; 杨欢欢; 杨超; 李彦波

    2015-01-01

    In this paper, the authors studied the andsites in Rongna ore block, Tiegelong Cu (Au-Ag) deposit, Duolong ore concentration area, Tibet, and used the zircon U-Pb data and petrogeochemistry of andsites to identify the petrogenetic age and tectonic setting of the andsites. The weighted average age of zircon U-Pb is 110.1 ± 0.7 Ma (MSWD=2.3) , which represents the petrogenesis age. An analysis of the whole rock sample shows that SiO2 values are 59.5%-61.48%, Al2O3 values are 16.14%-17.11%and Na2O+K2O values are 6.02%-6.63%;Mg# is of intermediate value. LILE such as Ba, Rb, Th, K are rich, HFSE such as Ta, Nb, P, Ti are relatively poor and characterized by Rb positive anomaly and obvious Zr, Hf negative anomalies. Petrological and geochemical studies show that the andesites are high potassium calc-alkaline rocks exhibiting the characteristics of Andean-type active continental margin volcanic rocks. They resulted probably from partial melting of subducted oceanic slab as well as miscibility with crustal material during the upward migration of the magma in the case that subducted oceanic slab didn’t interact with the mantle. They were the magma products of the northward subduction of Bangong Co-Nujiang Ocean and Lhasa and the collision collage process of Qiangtang terrane. In combination with other dating data and drilling core catalog data, the authors hold that the formation of andesites was later than the rock-forming and ore-forming stage of the Tiegelongnan high sulfur epithermal Cu (Au-Ag) deposits, which seems to have been the important condition for the preservation of the ore deposit.%本文主要对出露与西藏多龙矿集区铁格隆南矿区荣那矿段的安山岩开展了锆石U−Pb定年、岩石地球化学测试,旨在确定该套火山岩的成岩年龄及其形成的构造背景。安山岩的LA−ICP−MS锆石U−Pb加权平均年龄为(110.1±0.7) Ma (MSWD=2.3),代表了其成岩年龄。岩石SiO2为59.5%~61.48%;Al2O3为16.14%~17.11%

  4. Electronic dynamics under effect of a nonlinear Morse interaction and a static electric field

    Science.gov (United States)

    Ranciaro Neto, A.; de Moura, F. A. B. F.

    2016-11-01

    Considering non-interacting electrons in a one-dimension alloy in which atoms are coupled by a Morse potential, we study the system dynamics in the presence of a static electric field. Calculations are performed assuming a quantum mechanical treatment for the electronic transport and a classical Hamiltonian model for the lattice vibrations. We report numerical evidence of the existence of a soliton-electron pair, even when the electric field is turned on, and we offer a description of how the existence of such a phase depends on the magnitude of the electric field and the electron-phonon interaction.

  5. PLUTONIUM-ZIRCONIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  6. 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.

  7. NICKEL-BASE ALLOY

    Science.gov (United States)

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  8. Crystallization behavior of electroless Co-Ni-B alloy plated in magnetic field in presence of cerium

    Institute of Scientific and Technical Information of China (English)

    XUAN Tian-peng; ZHANG Lei; HUANG Qin-hua

    2006-01-01

    The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrometer, X-ray diffractometer,transmission electron microscope. The results show that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath.Because of the action of magnetic field and rare earth element cerium, the boron content in alloy decreases, while cobalt and nickel contents increase. As a result, the amorphous Co-Ni-B alloy transforms to the microcrystalline Co-Ni-B-Ce alloy when the plating is in general state, and the Co-Ni-B alloy makes a crystalline transformation because of the action of magnetic field and rare earth element cerium.

  9. Subcritical crack growth in two titanium alloys.

    Science.gov (United States)

    Williams, D. N.

    1973-01-01

    Measurement of subcritical crack growth during static loading of precracked titanium alloys in salt water using samples too thin for plane strain loading to predominate was examined as a method for determining the critical stress intensity for crack propagation in salt water. Significant internal crack growth followed by arrest was found at quite low stress intensities, but crack growth rates were relatively low. Assuming these techniques provided a reliable measurement of the critical stress intensity, the value for annealed Ti-4Al-1.5Mo-0.5V alloy was apparently about 35 ksi-in. to the 1/2 power, while that for annealed Ti-4Al-3Mo-1V was below 45 ksi-in. to the 1/2 power. Crack growth was also observed in tests conducted in both alloys in an air environment. At 65 ksi-in. to the 1/2 power, the extent of crack growth was greater in air than in salt water. Ti-4Al-3Mo-1V showed arrested crack growth in air at a stress intensity of 45 ksi-in. to the 1/2 power.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gebhart, J.M.; Kelly, M.D.

    1976-06-22

    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.

  11. Static analysis of function calls in Erlang

    Directory of Open Access Journals (Sweden)

    Dániel Horpácsi

    2013-06-01

    Full Text Available Functions and their relations can affect numerous properties and metrics of a functional program. To identify and represent the functions and their calling connections, software analysers commonly apply semantic function analysis, which derives the static call graph of the program, based on its source code. Function calls however may be dynamic and complex, making it difficult to statically identify the callee. Dynamic calls are determined just at run-time, static analysis therefore cannot be expected to fully identify every call. Nevertheless, by utilising the results of a properly performed data-flow analysis as well as taking ambiguous references into account, numerous dynamic calls are discoverable and representable. We consider cases where the identifiers of the callee are statically determined, but they flow into the call expression from a different program point, and also, we manage to handle function calls whose identifiers are not fully identifiable at compile-time. By utilising the improved reference analysis, we extend the static call graph with various information about dynamic function calls. We investigate such a function call analysis in the programming language Erlang.

  12. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  13. 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.

  14. 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

    ; 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...

  15. 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...

  16. 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.

  17. 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...

  18. Pheromone Static Routing Strategy for Complex Networks

    Science.gov (United States)

    Hu, Mao-Bin; Henry, Y. K. Lau; Ling, Xiang; Jiang, Rui

    2012-12-01

    We adopt the concept of using pheromones to generate a set of static paths that can reach the performance of global dynamic routing strategy [Phys. Rev. E 81 (2010) 016113]. The path generation method consists of two stages. In the first stage, a pheromone is dropped to the nodes by packets forwarded according to the global dynamic routing strategy. In the second stage, pheromone static paths are generated according to the pheromone density. The output paths can greatly improve traffic systems' overall capacity on different network structures, including scale-free networks, small-world networks and random graphs. Because the paths are static, the system needs much less computational resources than the global dynamic routing strategy.

  19. 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.

  20. Static Analysis for JavaScript

    DEFF Research Database (Denmark)

    Jensen, Simon Holm

    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 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...... 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...

  1. Mg based alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, S. [Univ. de Santiago de Chile (Chile). Fac. de Ingenieria; Garcia, G.; Serafini, D.; San Martin, A.

    1999-07-01

    In the present work, we studied the production of magnesium alloys, of stoichiometry 2Mg + Ni, by mechanical alloying (MA) and the behavior of the alloys under hydrogen in a Sievert`s type apparatus. The elemental powders were milled under argon atmosphere in a Spex 8000 high energy ball mill. The milled materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Only minimum amounts of the Mg{sub 2}Ni intermetallic compound was obtained after 22 h of milling time. Most of the material was sticked to the inner surface of the container as well as to the milling balls. Powders milled only for 12 hours transforms to the intermetallic at around 433 K. Effects of the MA on the hydrogen absorption kinetics were also studied. (orig.) 10 refs.

  2. 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

  3. Static cylindrical symmetry and conformal flatness

    CERN Document Server

    Herrera, L; Marcilhacy, G; Santos, N O

    2004-01-01

    We present the whole set of equations with regularity and matching conditions required for the description of physically meaningful static cylindrically symmmetric distributions of matter, smoothly matched to Levi-Civita vacuum spacetime. It is shown that the conformally flat solution with equal principal stresses represents an incompressible fluid. It is also proved that any conformally flat cylindrically symmetric static source cannot be matched through Darmois conditions to the Levi-Civita spacetime. Further evidence is given that when the Newtonian mass per unit length reaches 1/2 the spacetime has plane symmetry.

  4. Static and dynamic properties of Fibonacci multilayers

    Science.gov (United States)

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

    2013-05-01

    We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures.

  5. 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

  6. 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)

  7. Evaluation of Pb-17Li compatibility of ODS Fe-12Cr-5Al alloys

    Science.gov (United States)

    Unocic, Kinga A.; Hoelzer, David T.

    2016-10-01

    The Dual Coolant Lead Lithium (DCLL: eutectic Pb-17Li and He) blanket concept requires improved Pb-17Li compatibility with ferritic steels in order to demonstrate acceptable performance in fusion reactors. As an initial step, static Pb-17at.%Li (Pb-17Li) capsule experiments were conducted on new oxide dispersion strengthened (ODS) FeCrAl alloys ((1) Y2O3 (125Y), (2) Y2O3 + ZrO2 (125YZ), (3) Y2O3 + HfO2 (125YH), and (4) Y2O3 + TiO2 (125YT)) produced at ORNL via mechanical alloying (MA). Tests were conducted in static Pb-17Li for 1000 h at 700 °C. Alloys showed promising compatibility with Pb-17Li with small mass change after testing for 125YZ, 125YH and 125YT, while the 125Y alloy experienced the highest mass loss associated with some oxide spallation and subsequent alloy dissolution. X-ray diffraction methods identified the surface reaction product as LiAlO2 on all four alloys. A small decrease (∼1 at.%) in Al content beneath the oxide scale was observed in all four ODS alloys, which extended 60 μm beneath the oxide/metal interface. This indicates improvements in alloy dissolution by decreasing the amount of Al loss from the alloy. Scales formed on 125YZ, 125YH and 125YT were examined via scanning transmission electron microscopy (S/TEM) and revealed incorporation of Zr-, Hf-, and Ti-rich precipitates within the LiAlO2 product, respectively. This indicates an inward scale growth mechanism. Future work in flowing Pb-17Li is needed to further evaluate the effectiveness of this strategy in a test blanket module.

  8. 首饰用开金合金的研究与发展(2):首饰用开金合金的冶金学特性及强化机制%Investigation and Development of the Karat Gold Alloys for Jewelries (2):Metallurgical Features and Strengthening Mechanism of the Karat Gold Alloys for Jewelries

    Institute of Scientific and Technical Information of China (English)

    张永俐; 李关芳

    2004-01-01

    开金合金强度、硬度高,色彩丰富,可满足人们对首饰色彩多样性和饰品耐用性的要求,因而广泛用于首饰行业.作者综述了Au-Ag-Cu、Au-Ag-pd和Au-Cu-Ni等首饰用主要合金系统的冶金学特性,重点评述了首饰用Au-Ag-Cu系开金合金的强化机制和强化途径的研究现状及发展,包括晶粒尺寸控制的强化、冷加工硬化、合金元素固溶强化、热处理强化以及微合金化强化等.

  9. Effects of insoles contact on static balance.

    Science.gov (United States)

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

    2016-04-01

    [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.

  10. Static Checking of Interrupt-driven Software

    DEFF Research Database (Denmark)

    Brylow, Dennis; Damgaard, Niels; Palsberg, Jens

    2001-01-01

    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...

  11. 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.

  12. 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. Cranfield University

  13. 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...

  14. 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...

  15. A Logical Characterisation of Static Equivalence

    DEFF Research Database (Denmark)

    Hüttel, Hans; Pedersen, Michael D.

    2007-01-01

    The work of Abadi and Fournet introduces the notion of a frame to describe the knowledge of the environment of a cryptographic protocol. Frames are lists of terms; two frames are indistinguishable under the notion of static equivalence if they satisfy the same equations on terms. We present a first...

  16. Automatic incrementalization of Prolog based static analyses

    DEFF Research Database (Denmark)

    Eichberg, Michael; Kahl, Matthias; Saha, Diptikalyan;

    2007-01-01

    Modem development environments integrate various static analyses into the build process. Analyses that analyze the whole project whenever the project changes are impractical in this context. We present an approach to automatic incrementalization of analyses that are specified as tabled logic prog...

  17. Static Validation of a Voting Protocol

    DEFF Research Database (Denmark)

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

    2005-01-01

    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 formali...

  18. 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.

  19. Static Theory for Planar Ferromagnets and Antiferromagnets

    Institute of Scientific and Technical Information of China (English)

    Feng Bo HANG; Fang Hua LIN

    2001-01-01

    Here we generalize the "BBH"-asymptotic analysis to a simplified mathematical model for the planar ferromagnets and antiferromagncts. To develop such a static theory is a necessary step for a rigorous mathematical justification of dynamical laws for the magnetic vortices formally derived in [1] and [2].

  20. Monotone Comparative Statics for the Industry Composition

    DEFF Research Database (Denmark)

    Laugesen, Anders Rosenstand

    2015-01-01

    We let heterogeneous firms face decisions on a number of complementary activities in a monopolistically-competitive industry. The endogenous level of competition and selection regarding entry and exit of firms introduces a wedge between monotone comparative statics (MCS) at the firm level and MCS...

  1. Static shapes of levitated viscous drops

    Science.gov (United States)

    Duchemin, L.; Lister, J. R.; Lange, U.

    2005-06-01

    We consider the levitation of a drop of molten glass above a spherical porous mould, through which air is injected with constant velocity. The glass is assumed to be sufficiently viscous compared to air that motion in the drop is negligible. Thus static equilibrium shapes are determined by the coupling between the lubricating pressure in the supporting air cushion and the Young-Laplace equation. The upper surface of the drop is under constant atmospheric pressure; the static shape of the lower surface of the drop is computed using lubrication theory for the thin air film. Matching of the sessile curvature of the upper surface to the curvature of the mould gives rise to a series of capillary "brim" waves near the edge of the drop which scale with powers of a modified capillary number. Several branches of static solutions are found, such that there are multiple solutions for some drop volumes, but no physically reasonable solutions for other drop volumes. Comparison with experiments and full Navier-Stokes calculations suggests that the stability of the process can be predicted from the solution branches for the static shapes, and related to the persistence of brim waves to the centre of the drop. This suggestion remains to be confirmed by a formal stability analysis.

  2. 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.

  3. Onthe static and spherically symmetric gravitational field

    Science.gov (United States)

    Gottlieb, Ioan; Maftei, Gheorghe; Mociutchi, Cleopatra

    Starting from a generalization of Einstein 's theory of gravitation, proposed by one of the authors (Cleopatra Mociutchi), the authors study a particular spherical symmetric case. Among other one obtain the compatibility conditions for the existence of the static and spherically symmetruic gravitational filed in the case of extended Einstein equation.

  4. 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

  5. Plasma nitriding of titanium alloy: Effect of roughness, hardness, biocompatibility, and bonding with bone cement.

    Science.gov (United States)

    Khandaker, Morshed; Riahinezhad, Shahram; Li, Yanling; Vaughan, Melville B; Sultana, Fariha; Morris, Tracy L; Phinney, Lucas; Hossain, Khalid

    2016-11-25

    Titanium (Ti) alloys have been widely used in orthopedics and orthodontic surgeries as implants because of their beneficial chemical, mechanical, and biological properties. Improvement of these properties of a Ti alloy, Ti-6Al-4V Eli, is possible by the use of plasma nitriding treatment on the Ti alloy. The novelty of this study is the evaluation of a DC glow discharge nitrogen plasma treatment method on the surface, mechanical and biological properties of Ti alloy. Specifically, this study measured the chemical states, roughness, hardness, and biocompatibility of plasma nitride treated Ti-6Al-4V Eli as well as determined the effect of plasma treatment on the fracture strength between the Ti alloy and bone clement. This study hypothesized that DC glow discharge nitrogen plasma treatment may alter the surface chemical and mechanical states of the Ti alloy that may influence the fracture strength of implant/cement interfaces under static load. This study found that plasma nitride treatment on Ti alloy does not have effect on the roughness and biocompatibility (P value > 0.5), but significantly effect on the hardness and fracture strength of Ti-bone cement interfaces compared to those values of untreated Ti samples (P value < 0.5). Therefore, the DC glow discharge nitrogen plasma treated Ti alloy can potentially be used for orthopedic applications.

  6. Ideal solution behaviour of glassy Cu–Ti, Zr, Hf alloys and properties of amorphous copper

    Energy Technology Data Exchange (ETDEWEB)

    Ristić, R. [Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, HR-3100 Osijek (Croatia); Cooper, J.R. [Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, CB3 0HE Cambridge (United Kingdom); Zadro, K.; Pajić, D. [Department of Physics, Faculty of Science, Bijenička cesta 32, HR-10002 Zagreb (Croatia); Ivkov, J. [Institute of Physics, Bijenička cesta 46, HR-10002 Zagreb (Croatia); Babić, E. [Department of Physics, Faculty of Science, Bijenička cesta 32, HR-10002 Zagreb (Croatia)

    2015-02-05

    Highlights: • Ideal solution behaviour (ISB) is established in all Cu–Ti, Zr, Hf glassy alloys. • ISB enables reliable estimates for various properties of amorphous Cu. • ISB also impacts glass forming ability in these and probably other similar alloys. - Abstract: A comprehensive study of selected properties of amorphous (a) Cu–TE alloys (TE = Ti, Zr and Hf) has been performed. Data for average atomic volumes of a-Cu–Hf, Ti alloys combined with literature data show that ideal solution behaviour (Vegard’s law) extends over the whole glass forming range (GFR) in all a-Cu–TE alloys. This enables one to obtain an insight into some properties and probable atomic arrangements for both, a-TEs (Ristić et al., 2010) and a-Cu by extrapolation of the data for alloys. Indeed the atomic volumes and other properties studied for all a-Cu–TE alloys extrapolate to the same values for a-Cu. Depending on the property, these values are either close to those of crystalline (c) Cu, or are close to those for liquid (L) Cu. In particular, the electronic transport properties of a-Cu seem close to those of L-Cu, whereas the static properties, such as the density of states, and Young’s modulus, converge to those of c-Cu. The possible impact of these results on our understanding of a-Cu–TE alloys, including glass forming ability, is discussed.

  7. TUNGSTEN BASE ALLOYS

    Science.gov (United States)

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  8. 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

  9. Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

  10. Characterization of microstructures in metallic materials using static and dynamic acoustic signal processing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kalyanasundaram, P.; Raj, B.; Jayakumar, T. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2006-07-01

    Stainless steels are used in the industrial components of many chemical, petrochemical, process and nuclear industries. The microstructural characteristics of these materials can be determined by non-destructive evaluation (NDE) methods such as ultrasonic and acoustic emissions. Ultrasonic techniques are used primarily for detecting defects and static changes in materials, while acoustic emission techniques (AET) reveal the dynamic changes occurring in materials. This paper focused on the use of ultrasonic techniques to detect welding defects in austenitic stainless steel and maraging steel. The study addressed issues facing the use of ultrasonic techniques based on time and frequency domain signal analysis for characterizing changes in the microstructure of type 316 stainless steel and 9Cr-1Mo ferritic steel; thermomechanical processing of 15Cr-15Ni-2.3Mo-titanium modified austenitic stainless steel (alloy D9); and, the isothermal annealing behaviour of alloy D9. Ultrasonic spectral analysis based methodologies were also developed for grain size measurement in AISI type 316 stainless steel and modified 9Cr-1Mo ferritic steel. The feasibility of using acoustic emission techniques for detecting fatigue crack growth in 316 stainless steel was also discussed along with the use of AET for on-line monitoring of the aluminium alloy forging process. This study revealed the possibility of finding viable solutions for characterizing conventional processes and components, based on careful selection of parameters of the techniques and appropriate signal analysis methods. 5 refs., 7 figs.

  11. Strength of Hard Alloys,

    Science.gov (United States)

    Partial replacement of titanium carbide by tantalum carbide in three-phase WC-TiC-Co alloys tends to have a favorable effect on mechanical properties such as fatigue strength under bending and impact durability.

  12. Alloy Selection System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  13. 49 CFR Appendix H to Part 229 - Static Noise Test Protocols-In-Cab Static

    Science.gov (United States)

    2010-10-01

    ... for the in-cab static measurements of locomotives. I. Measurement Instrumentation The instrumentation... electronic form. (1) Name(s) of persons conducting the test, and the date of the test. (2) Description...

  14. First Everlasting Alloy

    Institute of Scientific and Technical Information of China (English)

    杨仲言

    1994-01-01

    There′s new alloy that apparently just won′t give up. When a pin was scraped along it the equivalent of one million times, the alloy-made of zirconium, palladium, and ruthenium—displayed no net loss of surface material. When astonished researchers at the National Institute of Standards and Technology(NIST) persevered with a five-million-cycle wear test, they got the same result.

  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. CYCLIC FATIGUE RESISTANCE OF AZ91 MAGNESIUM ALLOY

    Directory of Open Access Journals (Sweden)

    Aneta Němcová

    2009-11-01

    Full Text Available The paper deals with determination of principal mechanical properties and the investigation of fatigue behaviour of AZ91 magnesium alloy. The experimental material was made by squeeze casting technique and heat treated to obtain T4 state (solution annealing, when hard, brittle Mg17Al12 intermetallic phase is dissolved. The basic mechanical properties (Young’s modulus, ultimate tensile strength, yield strength, elongation to fracture and reduction of area were determined by static tensile test. Furthermore, fatigue parameters were investigated. The S-N curve on the basis of smooth test bars tested under symmetrical push-pull loading at room temperature was evaluated. The measured data were subsequently used for fitting with suitable regression functions (Kohout & Věchet and Stromeyer for determination of the fatigue parameters. Fatigue limit sigma-c of the studied alloy for 108 cycles is approaching 50 MPa. In addition, the fracture surfaces were observed by scanning electron microscopy. The failure analysis proved that the striations were observed in fatigue crack propagation area and in the area of static fracture was observed the transgranular ductile fracture. The structure of the studied alloy in the basic state and after heat treatment was observed by light and scanning electron microscopy.

  17. Atomic structure of water/Au, Ag, Cu and Pt atomic junctions.

    Science.gov (United States)

    Li, Yu; Kaneko, Satoshi; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

    2017-02-08

    Much progress has been made in understanding the transport properties of atomic-scale conductors. We prepared atomic-scale metal contacts of Cu, Ag, Au and Pt using a mechanically controllable break junction method at 10 K in a cryogenic vacuum. Water molecules were exposed to the metal atomic contacts and the effect of molecular adsorption was investigated by electronic conductance measurements. Statistical analysis of the electronic conductance showed that the water molecule(s) interacted with the surface of the inert Au contact and the reactive Cu ant Pt contacts, where molecular adsorption decreased the electronic conductance. A clear conductance signature of water adsorption was not apparent at the Ag contact. Detailed analysis of the conductance behaviour during a contact-stretching process indicated that metal atomic wires were formed for the Au and Pt contacts. The formation of an Au atomic wire consisting of low coordination number atoms leads to increased reactivity of the inert Au surface towards the adsorption of water.

  18. 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.

  19. 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.

  20. Dynamic Mechanical Behavior and Microstructural Evolution of the Al-6Mg Alloy Subjected to Three Treatment Conditions

    Institute of Scientific and Technical Information of China (English)

    LIN Musen; PANG Baojun; ZHANG Wei

    2012-01-01

    The mechanical properties of Al-6Mg alloy with three treatment states (Hl12,O and coldextruded states) were investigated at room and high temperatures using an INSTRON machine and a Split Hopkinson Pressure Bar (SHPB).Stress-strain curves of the alloy with different processes were obtained at a quasi-static strain rate of 5×10-4 s-1and dynamic strain rates of 1 400-4 200 s-1,respectively.The results suggest that,at room temperature,the three processed Al-6Mg alloys are all low sensitive to strain rate.The O state Al-6Mg alloy (Al-6Mg-O) exhibits the most ductility,while the cold-extruded Al-6Mg alloy (Al-6Mg-C)displays the highest strength.At elevated temperatures,the yield stresses and the differences in yield stress of the three processed alloys all decrease with increasing temperature under the quasi-static strain rate of 5× 10-4 s-1.Based on test results,modified Johnson-Cook(JC)constitutive models for the three processed Al-6Mg alloys were developed.The microstrucmres before and after deformation were examined by electron backscattered diffraction (EBSD) and further dynamic recrystallization (DRX) at the strain rate of 3 300 s-1 was discussed.

  1. Laser-induced agglomeration of gold and silver nanoparticles dispersed in liquid

    Science.gov (United States)

    Serkov, A. A.; Kuzmin, P. G.; Shafeev, G. A.

    2016-03-01

    Evolution of size distribution function, morphology, and extinction spectra of Ag nanoparticles and Au-Ag nanoparticles mixture dispersed in liquids under picosecond laser exposure are experimentally studied. It is shown that picosecond laser exposure of dense aqueous solutions of NPs (above 1014 particles per ml) leads to formation of elongated agglomerates. Time dependence of the size distribution function is monitored during irradiation process and compared to optical spectra and Transmission Electron Microscope images. Exposure of Au-Ag nanoparticles mixture is shown to result in formation of NPs chains consisting of Au and Ag, or Au-Ag alloy NPs.

  2. KCl-induced high temperature corrosion of selected commercial alloys. Part II: alumina and silica-formers

    DEFF Research Database (Denmark)

    Kiamehr, Saeed; Dahl, Kristian Vinter; Montgomery, Melanie;

    2016-01-01

    Laboratory testing on selected alumina and silica-forming alloys was performed to evaluate their performance against high temperature corrosion induced by potassium chloride (KCl). The alloys studied were FeCrAlY, Kanthal APM, Nimonic 80A, 214, 153MA and HR160. Exposure was conducted at 600 °C......). It was observed that alloying with aluminum did not lead to the formation of protective alumina for the studied alloys. The silicon containing stainless steel 153MA showed an analogous performance to low silicon austenitic stainless steels of similar chromium and nickel contents. For alloy HR160, a potassium...... in static laboratory air for the same duration and temperature with either KCl or K2CO3 deposits. Comparison of results obtained with these experiments showed that both potassium and chlorine can play a role in material degradation by KCl....

  3. In Vitro Degradation Behavior of Ternary Mg-Zn-Se and Mg-Zn-Cu Alloys as Biomaterials

    Science.gov (United States)

    Persaud-Sharma, Dharam; Budiansky, Noah

    2013-01-01

    In this study, the corrosion behavior of Mg-Zn-Se and Mg-Zn-Cu alloys was investigated to evaluate their corrosion behavior related to use as implantable biomaterials. The corrosion behavior of these alloys and a commercially available Mg-Zn alloy were examined using static solution electrochemical testing, dynamic solution gravimetric testing, ion leaching testing, and microscopic evaluation. Fluctuations in the pH of the Dulbecco’s Modified Eagles Medium (DMEM) used for the gravimetric and ion leaching immersion testing were also recorded over the 30-day duration to assess whether the media conditions induced by the alloy degradation would permit for cellular survival. Weight loss experimentation and electrochemical tests revealed the Mg-Zn-Cu alloy to have the greatest corrosion rate. PMID:24465245

  4. Observational evidence favours a static universe

    CERN Document Server

    Crawford, David F

    2010-01-01

    The common attribute of all Big Bang cosmologies is that they are based on the assumption that the universe is expanding. However examination of the evidence for this expansion clearly favours a static universe. The major topics considered are: Tolman surface brightness, angular size, type 1a supernovae, gamma ray bursts, galaxy distributions, quasar distributions, X-ray background radiation, cosmic microwave background radiation, radio source counts, quasar variability and the Butcher--Oemler effect. An analysis of the best raw data for these topics shows that they are consistent with expansion only if there is evolution that cancels the effects of expansion. An alternate cosmology, curvature cosmology, is in full agreement with the raw data. This tired-light cosmology predicts a well defined static and stable universe and is fully described. It not only predicts accurate values for the Hubble constant and the temperature of cosmic microwave background radiation but shows excellent agreement with most of the...

  5. Power analysis of static VAr compensators

    Energy Technology Data Exchange (ETDEWEB)

    Quintela, F.R.; Arevalo, J.M.G.; Redondo, R.C. [Escuela Tecnica Superior de Ingenieria Industrial, Universidad de Salamanca, 37700 Bejar (Spain)

    2008-07-15

    Analysis of three-phase loads usually assume them to be three impedances in a star or triangle connection. This is the reason why obtained results can only be considered valid for passive loads, strictly speaking. Analysis leading to the proposal of some static compensators is usually performed in this way, which induces to believe that this compensators are only valid for passive loads. An analysis procedure, which uses only powers to describe loads, is expounded in this paper. If applied to the analysis of static compensators, it reveals unequivocally their usefulness with active and passive three-phase loads. Therefore, this method is more general and, as it will be seen, easier. (author)

  6. Optimal Static Range Reporting in One Dimension

    DEFF Research Database (Denmark)

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

    2001-01-01

    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 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...... 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....

  7. Perturbative static four-quark potentials

    CERN Document Server

    Lang, J; Green, A M

    1995-01-01

    A first attempt to understand hadron dynamics at low energies in terms of the fundamental quark and gluon degrees of freedom incorporates the effects of the gluonic field into a potential depending only on the spatial positions of the quarks, which are considered in the infinite mass limit. A suitable framework for calculating such potentials between static quarks, i.e.\\ a generalization of the Wilson loop will be discussed. Making a connection with recent Monte Carlo lattice simulations for the lowest two energies of a system of two quarks and two antiquarks, the static qq\\bar{q}\\bar{q}-potential will be calculated in perturbation theory to fourth order. The result will be shown to be exactly equal to the prediction of a straightforward two-body approach, which in Monte Carlo lattice simulations has been found to be a reasonable approximation for very small interquark distances.

  8. 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.

  9. 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.

  10. 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.

  11. Static Gauge Potential from Noncritical Strings

    CERN Document Server

    Alvarez, Enrique; Alvarez, Enrique; Manjarin, Juan Jose

    2001-01-01

    The static gauge potential between heavy sources is computed from a recently introduced non-critical bosonic string background. When the sources are located at the infinity of the holographic coordinate, the linear dilaton behavior is recovered, which means that the potential is exactly linear in the separation between the sources. When the sources are moved towards the origin, a competing overconfining cubic branch appears, which is however disfavored energetically.

  12. Non-self-dual static gauge fields

    Science.gov (United States)

    Oh, C. H.; Teh, Rosy

    1980-01-01

    We exhibit exact non-self-dual static solutions to the SU(2) Yang-Mills field equations by solving the equation ∇2V+λV3=0 using cylindrical and spherical coordinates. The resulting gauge fields are complex and have singularities. For the cylindrically symmetric solution, we convert it into a real gauge field coupled to the Higgs field in the limit in which the self-interaction potential of the Higgs field vanishes.

  13. 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

  14. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan;

    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....

  15. Person Identification System using Static-dynamic signatures fusion

    OpenAIRE

    S.A Daramola; T.S Ibiyemi

    2010-01-01

    Off-line signature verification systems rely on static image of signature for person identification. Imposter can easily imitate the static image of signature of the genuine user due to lack of dynamic features. This paper proposes person identity verification system using fused static-dynamic signature features. Computational efficient technique is developed to extract and fuse static and dynamic features extracted from offline and online signatures of the same person. The training stage use...

  16. Static Versus Dynamic Stretching Effect on Agility Performance

    OpenAIRE

    Troumbley, Patrick

    2010-01-01

    The purpose of this study was to compare effects of static and dynamic stretching on explosive agility movements, and to examine the effect of the interaction of dynamic and static stretching prior to explosive agility movements. Fourteen men and 10 women performed the different warm-up protocols, including no warm-up (NWU), static stretching (SS), dynamic stretching (DS), and dynamic stretching with static stretching (DS+SS). The T-Drill was used to assess agility. The results indicated n...

  17. 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.

  18. 14 CFR 33.64 - Pressurized engine static parts.

    Science.gov (United States)

    2010-01-01

    ... engine static parts. (a) Strength. The applicant must establish by test, validated analysis, or a combination of both, that all static parts subject to significant gas or liquid pressure loads for a... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pressurized engine static parts....

  19. 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...

  20. 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...

  1. 49 CFR 238.203 - Static end strength.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Static end strength. 238.203 Section 238.203... Equipment § 238.203 Static end strength. (a)(1) Except as further specified in this paragraph or in.... (2) For a passenger car or a locomotive, the static end strength of unoccupied volumes may be...

  2. The Static Ladder Problem with Two Sources of Friction

    Science.gov (United States)

    Bennett, Jonathan; Mauney, Alex

    2011-01-01

    The problem of a ladder leaning against a wall in static equilibrium is a classic example encountered in introductory mechanics texts. Most discussions of this problem assume that the static frictional force between the ladder and wall can be ignored. A few authors consider the case where the static friction coefficients between ladder/wall…

  3. Selective dissolution in binary alloys

    Science.gov (United States)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  4. Static Enforcement of Static Separation-of-Duty Policies in Usage Control Authorization Models

    Science.gov (United States)

    Lu, Jianfeng; Li, Ruixuan; Hu, Jinwei; Xu, Dewu

    Separation-of-Duty (SoD) is a fundamental security principle for prevention of fraud and errors in computer security. It has been studied extensively in traditional access control models. However, the research of SoD policy in the recently proposed usage control (UCON) model has not been well studied. This paper formulates and studies the fundamental problem of static enforcement of static SoD (SSoD) policies in the context of UCONA, a sub-model of UCON only considering authorizations. Firstly, we define a set-based specification of SSoD policies, and the safety checking problem for SSoD in UCONA. Secondly, we study the problem of determining whether an SSoD policy is enforceable. Thirdly, we show that it is intractable (coNP-complete) to direct statically enforce SSoD policies in UCONA, while checking whether a UCONA state satisfies a set of static mutually exclusive attribute (SMEA) constraints is efficient, which provides a justification for using SMEA constraints to enforce SSoD policies. Finally, we introduce a indirect static enforcement for SSoD policies in UCONA. We show how to generate the least restrictive SMEA constraints for enforcing SSoD policies in UCONA, by using the attribute-level SSoD requirement as an intermediate step. The results are fundamental to understanding SSoD policies in UCON.

  5. 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...

  6. 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.

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

    OpenAIRE

    Gao-Xin Wang; You-Liang Ding; Peng Sun; Lai-Li Wu; Qing Yue

    2015-01-01

    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 rem...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. EFFECT OF SPECIMEN ASPECT RATIO ON FATIGUE LIFE OF CLOSED CELL Al-Si-Ca ALLOY FOAM

    Institute of Scientific and Technical Information of China (English)

    Amkee Kim; Ilhyun Kim

    2008-01-01

    Quasi-static and compressive fatigue tests on the closed cell Al-Si-Ca alloy foam specimens with three different aspect ratios were performed.It turned out that the onset of cyclic shortening of foam with a lower aspect ratio took place earlier and the fatigue strength was lower compared with the specimen with a higher aspect ratio,although aU the dimensions of specimen satisfied the seven times the cell size criterion,while the quasi-static stress-strain curves were almost same having same Young's modulus,yield stress and plateau stress.Therefore,the seven times the cell size criterion for the quasi-static compression behavior was not applicable to the fatigue analysis of Al-Si-Ca alloy foam.

  18. Monotone Comparative Statics for the Industry Composition

    DEFF Research Database (Denmark)

    Bache, Peter Arendorf; Laugesen, Anders

    for the industry composition. The latter phenomenon is dened as rst-order stochastic dominance shifts in the equilibrium distributions of all activities across active rms. We provide sucient conditions for MCS at both levels of analysis and show that we may have either type of MCS without the other....... It is therefore possible that rm-level complementarities manifest themselves more clearly at the industry level than at the rm level during comparative statics. This turns out to be the case for a large number of models and shocks considered in the recent trade literature for which we provide strong, novel...

  19. 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

  20. 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.

  1. Static validation of licence conformance policies

    DEFF Research Database (Denmark)

    Hansen, Rene Rydhof; Nielson, Flemming; Nielson, Hanne Riis

    2008-01-01

    Policy conformance is a security property gaining importance due to commercial interest like Digital Rights Management. It is well known that static analysis can be used to validate a number of more classical security policies, such as discretionary and mandatory access control policies, as well...... as communication protocols using symmetric and asymmetric cryptography. In this work we show how to develop a Flow Logic for validating the conformance of client software with respect to a licence conformance policy. Our approach is sufficiently flexible that it extends to fully open systems that can admit new...

  2. QuickChecking Static Analysis Properties

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Møller, Anders

    2015-01-01

    , to verified fixed point checking. In this paper we demonstrate how quickchecking can be useful for testing a range of static analysis properties with limited effort. We show how to check a range of algebraic lattice properties, to help ensure that an implementation follows the formal specification...... of a lattice. Moreover, we offer a number of generic, type-safe combinators to check transfer functions and operators on lattices, to help ensure that these are, e.g., monotone, strict, or invariant. We substantiate our claims by quickchecking a type analysis for the Lua programming language...

  3. Management of Statically Modifiable Prolog Code

    Institute of Scientific and Technical Information of China (English)

    张晨曦; 慈云桂

    1989-01-01

    The Warren Abstract Machine is an efficient execution model for Prolog,which has become the basis of many high performance Prolog systems.However.little support for the implementation of the non-logical components of Prolog is provided in the WAM.The original Warren code is not modifiable.In this paper,we show how static modifications of Warren code can be achieved by adding a few instructions and a little extra information to the code.The implementation of the code manager is discussed.Algorithms for some basic operations are given.

  4. Compiler-assisted static checkpoint insertion

    Science.gov (United States)

    Long, Junsheng; Fuchs, W. K.; Abraham, Jacob A.

    1992-01-01

    This paper describes a compiler-assisted approach for static checkpoint insertion. Instead of fixing the checkpoint location before program execution, a compiler enhanced polling mechanism is utilized to maintain both the desired checkpoint intervals and reproducible checkpoint 1ocations. The technique has been implemented in a GNU CC compiler for Sun 3 and Sun 4 (Sparc) processors. Experiments demonstrate that the approach provides for stable checkpoint intervals and reproducible checkpoint placements with performance overhead comparable to a previously presented compiler assisted dynamic scheme (CATCH) utilizing the system clock.

  5. 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

  6. Cancer progression modeling using static sample data.

    Science.gov (United States)

    Sun, Yijun; Yao, Jin; Nowak, Norma J; Goodison, Steve

    2014-01-01

    As molecular profiling data continues to accumulate, the design of integrative computational analyses that can provide insights into the dynamic aspects of cancer progression becomes feasible. Here, we present a novel computational method for the construction of cancer progression models based on the analysis of static tumor samples. We demonstrate the reliability of the method with simulated data, and describe the application to breast cancer data. Our findings support a linear, branching model for breast cancer progression. An interactive model facilitates the identification of key molecular events in the advance of disease to malignancy.

  7. Static aeroelastic analysis for generic configuration wing

    Science.gov (United States)

    Lee, IN; Miura, Hirokazu; Chargin, Mladen K.

    1991-01-01

    A static aeroelastic analysis capability that calculates flexible air loads for generic configuration wings was developed. It was made possible by integrating a finite element structural analysis code (MSC/NASTRAN) and a panel code of aerodynamic analysis based on linear potential flow theory. The framework already built in MSC/NASTRAN was used, and the aerodynamic influence coefficient matrix was computed externally and inserted in the NASTRAN by means of a DMAP program. It was shown that deformation and flexible air loads of an oblique wing configuration including asymmetric wings can be calculated reliably by this code both in subsonic and supersonic speeds.

  8. Static Model of Cement Rotary Kiln

    Directory of Open Access Journals (Sweden)

    Omar D. Hernández-Arboleda

    2013-11-01

    Full Text Available In this paper, a static model of cement rotary kilns is proposed. The system model is obtained through polynomial series. The proposed model is contrasted with data of a real plant, where optimal results are obtained. Expected results are measured with respect to the clinker production and the combustible consumption is measured in relation with the consumption calorific. The expected result of the approach is the increase of the profitability of the factory through the decrease of the consumption of the combustible.

  9. 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.

  10. Strip Casting of High Performance Structural Alloys

    Institute of Scientific and Technical Information of China (English)

    S S Park; J G Lee; Nack J Kim

    2004-01-01

    There exists a great need for the development of high performance alloys due to increasing demands for energy conservation and environmental protection. Application of strip casting shows a strong potential for the improvement of properties of existing alloys and also for the development of novel alloy systems with superior properties. The present paper reviews our Center's activities in the development of high performance alloys by strip casting. Examples include (1) Al alloys, (2) wrought Mg alloys, and (3) bulk metallic glass (BMG) alloys.

  11. 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...

  12. Tungsten Alloy Outgassing Measurements

    CERN Document Server

    Rutherfoord, John P; Shaver, L

    1999-01-01

    Tungsten alloys have not seen extensive use in liquid argon calorimeters so far. Because the manufacturing process for tungsten is different from the more common metals used in liquid argon there is concern that tungsten could poison the argon thereby creating difficulties for precision calorimetry. In this paper we report measurements of outgassing from the tungsten alloy slugs proposed for use in the ATLAS FCal module and estimate limits on potential poisoning with reasonable assumptions. This estimate gives an upper limit poisoning rate of

  13. Static and dynamic oxidation of Ti-14Al-21Nb and coatings

    Science.gov (United States)

    Wiedemann, K. E.; Sankaran, S. N.; Clark, R. K.; Wallace, T. A.

    1989-01-01

    The oxidation of Ti-14Al-21Nb (wt pct) was studied under static conditions at 649 to 1093 C for as long as 120 hr, and under simulated hypersonic flight (dynamic oxidation) conditions at 982 C for as many as 16 half-hour cycles. Under simulated hypersonic flight conditions heavy oxidation and spalling of the oxide was observed. It was concluded that titanium aluminides used in hypersonic applications must have oxidation-protective coatings. In this preliminary study coatings about 1 micron thick were applied by sputter deposition, from solutions, and from sol-gels. It was found that, because of cracks and porosity, the sputter-deposited coatings did not have sufficient film integrity to shield the alloy. Some of the coatings applied from sol-gels demonstrated film integrity in 1 hr exposures at 982 C.

  14. Robot-Crawler: Statically Balanced Gaits

    Directory of Open Access Journals (Sweden)

    S. Parasuraman

    2012-12-01

    Full Text Available This paper presents a new statically balanced walking technique for a robot‐crawler. The gait design and the control of the robot crawler aim to achieve stability while walking. This statically balanced gait has to be designed in a different fashion to a wheeled robot, as there are discrete changes in the support of the robot when its legs are lifted or placed on the ground. The stability of the robot depends on how the legs are positioned relative to the body and also on the sequence and timing with which the legs are lifted and placed. In order to reduce the risk of stability loss while walking, a measure for the robot stability (so‐called stability margin is typically used in the gait and motion planning. In this paper different biological behaviours of four‐legged animals are studied and mapped on a quad-legrobot‐crawler. Experiments were carried out on the forward walking gaits of lizards and horses. Based on these results, the stability margins of different gaits are discussed and compared.

  15. 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...

  16. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  17. Shape Memory Alloy Actuator

    Science.gov (United States)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  18. Pareto-optimal alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Johannesson, Gisli Holmar; Ruban, Andrei;

    2003-01-01

    and the 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...

  19. Commercial Alloys for Sulfuric Acid Vaporization in Thermochemical Hydrogen Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Thomas M. Lillo; Karen M. Delezene-Briggs

    2005-10-01

    Most thermochemical cycles being considered for producing hydrogen include a processing stream in which dilute sulfuric acid is concentrated, vaporized and then decomposed over a catalyst. The sulfuric acid vaporizer is exposed to highly aggressive conditions. Liquid sulfuric acid will be present at a concentration of >96 wt% (>90 mol %) H2SO4 and temperatures exceeding 400oC [Brown, et. al, 2003]. The system will also be pressurized, 0.7-3.5 MPa, to keep the sulfuric acid in the liquid state at this temperature and acid concentration. These conditions far exceed those found in the commercial sulfuric acid generation, regeneration and handling industries. Exotic materials, e.g. ceramics, precious metals, clad materials, etc., have been proposed for this application [Wong, et. al., 2005]. However, development time, costs, reliability, safety concerns and/or certification issues plague such solutions and should be considered as relatively long-term, optimum solutions. A more cost-effective (and relatively near-term) solution would be to use commercially-available metallic alloys to demonstrate the cycle and study process variables. However, the corrosion behavior of commercial alloys in sulfuric acid is rarely characterized above the natural boiling point of concentrated sulfuric acid (~250oC at 1 atm). Therefore a screening study was undertaken to evaluate the suitability of various commercial alloys for concentration and vaporization of high-temperature sulfuric acid. Initially alloys were subjected to static corrosion tests in concentrated sulfuric acid (~95-97% H2SO4) at temperatures and exposure times up to 200oC and 480 hours, respectively. Alloys with a corrosion rate of less than 5 mm/year were then subjected to static corrosion tests at a pressure of 1.4 MPa and temperatures up to 375oC. Exposure times were shorter due to safety concerns and ranged from as short as 5 hours up to 144 hours. The materials evaluated included nickel-, iron- and cobalt

  20. 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.

  1. Flow stress equation for multipass hot-rolling of aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A series of simple axisymmetric compression tests were carried out on the computer servo-controlled Gleeble 1 500 machine when strain rates ranged between 0.05-25 s-1 and deformation temperature 300-500 ℃. The results show that flow stress is related to the Zener-Hollonom parameter Z and strain, as well as the static recrystallization fraction between passes during multipass hot deformation of 5182 aluminum alloy. Hence, a modified exponential flow stress equation was presented by considering the values of lnA and β as functions of strain, and by using the uniform softening method and incorporating the static recrystallization fraction between passes to consider the effects of residual strain during multipass hot-rolling of 5182 aluminum alloy. The validity of the equation was examined by a typical non-isothermal multipass deformation test.

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

    Directory of Open Access Journals (Sweden)

    A. Białobrzeski

    2007-07-01

    Full Text Available 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 its operation. Also automotive industry introduces to vehicle’s structure an elements (castings manufactured from such alloys. On metallic matrix of magnesium alloys with lithium are also manufactured a composites reinforced with e.g. ceramic fiber, which are used as lightweight and resistant structure materials. The paper presents an attempt of implementation of ATND method (Thermal-Voltage-Derivative Analysis to monitoring of crystallization process of ultra-lightweight Mg-Li alloys. Investigated magnesium alloys with contents of about 2,3% Li, 10% Li and 11 % Li were produced in the Foundry Research Institute. Registration of melting and crystallization processes was made with use of the ATND method. Results of preliminary tests are shown in graphical form.

  3. Compressive mechanical compatibility of anisotropic porous Ti6Al4V alloys in the range of physiological strain rate for cortical bone implant applications.

    Science.gov (United States)

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian

    2015-09-01

    Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications.

  4. Frequency dependence of the superparamagnetic transition in a Finemet-type nanocrystalline alloy

    Energy Technology Data Exchange (ETDEWEB)

    Franco, V.; Blazquez, J.S.; Conde, C.F.; Conde, A. [Dpto. Fisica de la Materia Condensada. ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080-Sevilla (Spain); Kiss, L.F.; Kemeny, T. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences. P.O. Box 49, 1525-Budapest (Hungary); Hillier, A.D. [ISIS Facility, CCLRC, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom)

    2004-12-01

    The transition to superparamagnetism in a Cr-containing Finemet alloy has been studied by means of ac susceptibility and muon spin relaxation experiments. The influence of bias field and measuring frequency has been analyzed. The transition temperature is controlled by the interaction between the particles. These results are consistent with previous static magnetic measurements. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. The effect of zirconium on the cyclic oxidation of NiCrAl alloys

    Science.gov (United States)

    Barrett, C. A.; Khan, A. S.; Lowell, C. E.

    1981-01-01

    This paper examines results with cyclic oxidation tests of Ni(9-20) Cr(15-30) Al-(x)Zr alloys carried out at 1100 C and 1200 C in static air. The concentration of zirconium varies from 0 to 0.63 atomic percent. Significant aluminum penetration is found in metallographic and electron microscopic examination of oxidized surfaces. Small amounts of zirconium lead to minimal penetration, and with increased zirconium content pronounced oxide penetration is observed.

  6. Advanced ordered intermetallic alloy deployment

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Maziasz, P.J.; Easton, D.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

  7. 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.

  8. The Spectrum of Static Subtracted Geometries

    CERN Document Server

    Andrade, Tomas; Cohen-Maldonado, Diego

    2016-01-01

    Subtracted geometries are black hole solutions of the four dimensional STU model with rather interesting ties to asymptotically flat black holes. In addition, a peculiar feature is that the solutions to the Klein-Gordon equation on this subtracted background can be organized according to representations of the conformal group $SO(2,2)$. We test if this behavior persists for the linearized fluctuations of gravitational and matter fields on static, electrically charged backgrounds of this kind. We find that there is a subsector of the modes that do display conformal symmetry, while some modes do not. We also discuss two different effective actions that describe these subtracted geometries and how the spectrum of quasinormal modes is dramatically different depending upon the action used.

  9. Static and dynamic friction of hierarchical surfaces

    Science.gov (United States)

    Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M.

    2016-12-01

    Hierarchical structures are very common in nature, but only recently have they been systematically studied in materials science, in order to understand the specific effects they can have on the mechanical properties of various systems. Structural hierarchy provides a way to tune and optimize macroscopic mechanical properties starting from simple base constituents and new materials are nowadays designed exploiting this possibility. This can be true also in the field of tribology. In this paper we study the effect of hierarchical patterned surfaces on the static and dynamic friction coefficients of an elastic material. Our results are obtained by means of numerical simulations using a one-dimensional spring-block model, which has previously been used to investigate various aspects of friction. Despite the simplicity of the model, we highlight some possible mechanisms that explain how hierarchical structures can significantly modify the friction coefficients of a material, providing a means to achieve tunability.

  10. 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.

  11. Landau problem in the static schwarzschild universe

    Directory of Open Access Journals (Sweden)

    A Jafari

    2013-09-01

    Full Text Available  This paper considers the Landau problem in an elected static space time and the are erased levels shifts which are erased as a metric deviation from the Minkowski space time. This research is based on the Weber’s method. We try to rewrite the equation of motion of particles in the presence of the gravitational effects and consider the regions limited with the tangent spaces conditions. I t would be reasonable to assume the nonrelativistic particles with low speed. We show that due to the Weber’s method, the tangent space is always available. Another assumption of this article is time independent tangent space of Schwarzschild universe and use of Riemann’s normal coordinates.

  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. Static aeroelastic analysis of composite wing

    Science.gov (United States)

    Lee, IN; Hong, Chang Sun; Miura, Hirokazu; Kim, Seung KO

    1990-01-01

    A static aeroelastic analysis capability that can predict aerodynamic loads for the deformed shape of the composite wing has been developed. The finite element method (FEM) was used for composite plate structural analysis, and the linear vortex lattice method (VLM) was used for steady aerodynamic analysis. The final deformed shape of the wing due to applied forces is determined by iterative manner using FEM and VLM. FEM and VLM analysis are related by a surface spline interpolation procedure. The wing with Gr/Ep composite material has been investigated to see the wing deformation effect. Aerodynamic load change due to wing flexibility has been investigated. Also, the effect of fiber orientation and sweep angle on the deformation pattern and aerodynamic coefficients are examined. For a certain fiber orientation, the deflection and aerodynamic loading of the composite wing is very much reduced. The swept forward wing has more significant effect of wing flexibility on aerodynamic coefficient than the swept back wing does.

  14. Static aeroelastic analysis for generic configuration aircraft

    Science.gov (United States)

    Lee, IN; Miura, Hirokazu; Chargin, Mladen K.

    1987-01-01

    A static aeroelastic analysis capability that can calculate flexible air loads for generic configuration aircraft was developed. It was made possible by integrating a finite element structural analysis code (MSC/NASTRAN) and a panel code of aerodynamic analysis based on linear potential flow theory. The framework already built in MSC/NASTRAN was used and the aerodynamic influence coefficient matrix is computed externally and inserted in the NASTRAN by means of a DMAP program. It was shown that deformation and flexible airloads of an oblique wing aircraft can be calculated reliably by this code both in subsonic and supersonic speeds. Preliminary results indicating importance of flexibility in calculating air loads for this type of aircraft are presented.

  15. Distributed static linear Gaussian models using consensus.

    Science.gov (United States)

    Belanovic, Pavle; Valcarcel Macua, Sergio; Zazo, Santiago

    2012-10-01

    Algorithms for distributed agreement are a powerful means for formulating distributed versions of existing centralized algorithms. We present a toolkit for this task and show how it can be used systematically to design fully distributed algorithms for static linear Gaussian models, including principal component analysis, factor analysis, and probabilistic principal component analysis. These algorithms do not rely on a fusion center, require only low-volume local (1-hop neighborhood) communications, and are thus efficient, scalable, and robust. We show how they are also guaranteed to asymptotically converge to the same solution as the corresponding existing centralized algorithms. Finally, we illustrate the functioning of our algorithms on two examples, and examine the inherent cost-performance trade-off.

  16. Construction of STACY (Static Experiment Critical Facility)

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Kiyonobu; Onodera, Seiji; Hirose, Hideyuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-08-01

    Two critical assemblies, STACY (Static Experiment Critical Facility) and TRACY (Transient Experiment Critical Facility), were constructed in NUCEF (Nuclear Fuel Cycle Safety Engineering Research Facility) to promote researches on the criticality safety at a reprocessing facility. STACY aims at providing critical data of uranium nitrate solution, plutonium nitrate solution and their mixture while varying concentration of solution fuel, core tank shape and size and neutron reflecting condition. STACY achieved first criticality in February 1995, and passed the licensing inspection by STA (Science and Technology Agency of Japan) in May. After that a series of critical experiments commenced with 10 w/o enriched uranium solution. This report describes the outline of STACY at the end of FY 1996. (author)

  17. 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 carried into the structure as in-plane forces by plate action in each element. These in-plane forces are then carried through the plate structure to the supports as in-plane forces by membrane action. The consequence is that the spatial stability of the structure can be simply analysed by considering...... the plate system as only subject to in-plane loads. The stability of such systems is based on the fact that each plane element is held fixed in space by three fixed support lines and that these support lines can be provided by three plane neighbour elements. This means that the spatial stability of a plate...

  18. Static impedance behavior of programmable metallization cells

    Science.gov (United States)

    Rajabi, S.; Saremi, M.; Barnaby, H. J.; Edwards, A.; Kozicki, M. N.; Mitkova, M.; Mahalanabis, D.; Gonzalez-Velo, Y.; Mahmud, A.

    2015-04-01

    Programmable metallization cell (PMC) devices work by growing and dissolving a conducting metallic bridge across a chalcogenide glass (ChG) solid electrolyte, which changes the resistance of the cell. PMC operation relies on the incorporation of metal ions in the ChG films via photo-doping to lower the off-state resistance and stabilize resistive switching, and subsequent transport of these ions by electric fields induced from an externally applied bias. In this paper, the static on- and off-state resistance of a PMC device composed of a layered (Ag-rich/Ag-poor) Ge30Se70 ChG film with active Ag and inert Ni electrodes is characterized and modeled using three dimensional simulation code. Calibrating the model to experimental data enables the extraction of device parameters such as material bandgaps, workfunctions, density of states, carrier mobilities, dielectric constants, and affinities.

  19. 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.

  20. 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.

  1. 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.

  2. Static gravitational equations of general relativity and "the fifth force"

    Science.gov (United States)

    Das, A.

    2015-10-01

    Einstein's static field equations are investigated in various coordinate charts. After comparing Newtonian gravitational theory (in a curvilinear coordinate chart) with various charts of Einstein's static gravitational equations, the most appropriate choice of the coordinate chart for Einstein's static field equations is made. As a consequence, Einstein's equations imply the non-linear potential equation instead of the usual Poisson's equation of the Newtonian theory. Investigating the non-linear potential equation above in the spherically symmetric cases, the corresponding potentials yield scenarios comparable to "the fifth force". Next, static gravitational and electric fields generated by an incoherent charged dust are investigated. The corresponding non-linear potential equation is derived. Finally, the static Einstein-Maxwell-Klein-Gordon equations are explored and again, the corresponding non-linear potential equation is obtained. This potential resembles the static Higgs boson field.

  3. Effects of static magnetic fields on plants.

    Science.gov (United States)

    Kuznetsov, O.

    In our recent experiment on STS-107 (MFA-Biotube) we took advantage of the magnetic heterogeneity of the gravity receptor cells of flax roots, namely stronger diamagnetism of starch-filled amyloplasts compared to cytoplasm (Δ ≊ HGMF, grad(H2/2) up to 109-1010 Oe2/cm) of the experimental chambers (MFCs) repelled amyloplasts from the zones of stronger field thus providing a directional stimulus for plant gravisensing system in microgravity, and causing the roots to react. Such reaction was observed in the video downlink pictures. Unfortunately, the ``Columbia'' tragedy caused loss of the plant material and most of the images, thus preventing us from detailed studies of the results. Currently we are looking for a possibility to repeat this experiment. Therefore, it is very important to understand, what other effects (besides displacing amyloplasts) static magnetic fields with intensities 0 to 2.5104 Oe, and with the size of the area of non-uniformity 10-3 to 1 cm. These effects were estimated theoretically and tested experimentally. No statistically significant differences in growth rates or rates of gravicurvature were observed in experiments with Linum, Arabidopsis, Hordeum, Avena, Ceratodon and Chara between the plants grown in uniform magnetic fields of various intensities (102 to 2.5104 Oe) and those grown in the Earth's magnetic field. Microscopic studies also did not detect any structural differences between test and control plants. The magnitudes of possible effects of static magnetic fields on plant cells and organs (including effects on ion currents, magneto-hydrodynamic effects in moving cytoplasm, ponderomotive forces on other cellular structures, effects on some biochemical reactions and biomolecules) were estimated theoretically. The estimations have shown, that these effects are small compared to the thermodynamic noise and thus are insignificant. Both theoretical estimations and control experiments confirm, that intracellular magnetophoresis of

  4. Mechanical behavior of ultrafine-grained materials under combined static and dynamic loadings

    Directory of Open Access Journals (Sweden)

    Guo Y.Z.

    2015-01-01

    Full Text Available Ultrafine-grained (UFG materials have extensive prospects for engineering application due to their excellent mechanical properties. However, the grain size decrease reduces their strain hardening ability and makes UFG materials more susceptible to deformation instability such as shear localization. In most cases, critical shear strain is taken as the criterion for formation of shear localization under impact loading or adiabatic shear band (ASB. Recently, some researchers found that the formation of ASB was determined only by the dynamic loading process and had nothing to do with its static loading history. They proposed for coarse-grained metals a dynamic stored energy-based criterion for ASB and verified it by some experiments. In this study, we will focus on the shear localization behavior of UFG metals such as UFG titanium and magnesium alloy AZ31. Quasi-static loading and dynamic loading will be applied on the same specimen alternately. The shear localization behavior will be analyzed and the criterion of its formation will be evaluated.

  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. Comparing dynamic and static test results of bored piles

    OpenAIRE

    Long, Michael

    2007-01-01

    Due to increasing time, cost and transportation difficulties, Irish contractors are seeking an alternative to conventional static pile load tests. As a result several firms have adopted dynamic testing techniques to supplement and in some cases to replace conventional static tests. In order to assess the reliability of the systems and to address the concerns of owners and consulting engineers, a database comprising 43 pairs of static and dynamic tests on piles from 24 sites aro...

  7. Evaluation of the CoCrTaPt alloy for longitudinal magnetic recording

    Science.gov (United States)

    Cheng, Yuanda; Sedighi, Mojtaba; Lam, Irene; Gardner, Richard A.; Yang, ZhiJun; Scheinfein, Michael R.

    1994-05-01

    A quaternary alloy of CoCrTaPt with a composition of 80-10-4-6 (in at. %) was evaluated for its magnetic and recording properties. Samples of C/CoCrTaPt/Cr recording media were prepared by dc magnetron sputtering on circumferentially textured Al/NiP substrates. The effects on static magnetic properties and recording performance were studied for different substrate preheating times, Cr underlayer thicknesses, and Co-alloy layer thicknesses. It was found that both the coercivity Hc and remanent magnetization Mr increased with substrate preheating time. Hc also increased with Cr underlayer thickness, as expected. The Mrδ value depended linearly on the Co-alloy layer thickness. In addition, we found that the coercivity increased dramatically as the magnetic layer thickness decreased from ˜800 to ˜200 Å. For a sample with a 235-Å CoCrTaPt magnetic layer and ˜1000-Å Cr underlayer, the coercivity was found to be ≳2700 Oe. Parametric evaluation showed that CoCrTaPt samples have performance similar to samples of CoCrTa and, because of the Pt addition, the CoCrTaPt alloy offers significantly higher attainable coercivities than the CoCrTa alloy. Therefore, the CoCrTaPt alloy proves to be a good candidate for use in high density recording media which require coercivity of higher than 2000 Oe.

  8. Microstructural, mechanical, corrosion and cytotoxicity characterization of the hot forged FeMn30(wt.%) alloy.

    Science.gov (United States)

    Čapek, Jaroslav; Kubásek, Jiří; Vojtěch, Dalibor; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-01-01

    An interest in biodegradable metallic materials has been increasing in the last two decades. Besides magnesium based materials, iron-manganese alloys have been considered as possible candidates for fabrication of biodegradable stents and orthopedic implants. In this study, we prepared a hot forged FeMn30 (wt.%) alloy and investigated its microstructural, mechanical and corrosion characteristics as well as cytotoxicity towards mouse L 929 fibroblasts. The obtained results were compared with those of iron. The FeMn30 alloy was composed of antiferromagnetic γ-austenite and ε-martensite phases and possessed better mechanical properties than iron and even that of 316 L steel. The potentiodynamic measurements in simulated body fluids showed that alloying with manganese lowered the free corrosion potential and enhanced the corrosion rate, compared to iron. On the other hand, the corrosion rate of FeMn30 obtained by a semi-static immersion test was significantly lower than that of iron, most likely due to a higher degree of alkalization in sample surrounding. The presence of manganese in the alloy slightly enhanced toxicity towards the L 929 cells; however, the toxicity did not exceed the allowed limit and FeMn30 alloy fulfilled the requirements of the ISO 10993-5 standard.

  9. Substructural influence in the hot rolling of Al alloys

    Science.gov (United States)

    McQueen, H. J.

    1998-06-01

    The industrial rolling of aluminum alloys is generally conducted in multistage schedules of 10-15 passes partly on reversing mills and partly on continuous mills with temperature declining from 500°C to between 300°C and 250°C. Static recrystallization may take place in long intervals after passes with higher temperature and strain. During lower temperature intervals, only static recovery takes place so that in the following passes the flow curves exhibit higher initial stresses. Dynamic recovery decreases gradually through the hot-, warm-, and cold-working ranges but is reduced as the concentration of solutes and particles increase. Recrystallization is much more sensitive to temperature and alloying and is retarded by increased dynamic recovery. The texture of sheet depends on lattice-dependent Taylor rotations during dislocation slip, enhanced recovery of certain deformation band orientations, and preferred nucleation and growth during interpass pauses or annealing. Schedule optimization can be guided by physical simulation or modeling based on recrystallization kinetics to attain selected strengthening substructure, recrystallized grain size, and texture for product earing control.

  10. Tungsten carbide laser alloying of a low alloyed steel

    Science.gov (United States)

    Cojocaru, Mihai; Taca, Mihaela

    1996-10-01

    Laser alloying is a way to change the composition of metal surfaces in order to improve their corrosion-resistance, high-temperature strength and hardness. The results of a structural and phase analysis of a tungsten carbide based surface layer prepared by laser alloying of a low carbon steel substrate are presented. Structure, phase composition and microhardness of surface alloyed layers have been investigated. The surface of the samples exhibited a thin layer with a different chemical and phase composition. An increase in alloyed surface hardness and wear-resistance was observed.

  11. Filler metal alloy for welding cast nickel aluminide alloys

    Science.gov (United States)

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  12. Filler metal alloy for welding cast nickel aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  13. Materials data handbook, Inconel alloy 718

    Science.gov (United States)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on Inconel alloy 718 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  14. SINTERED REFRACTORY TUNGSTEN ALLOYS. Gesinterte hochschmelzende wolframlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, R.; Sedlatschek, K.; Braun, H.

    1971-12-15

    Dependence of the melting point of the refractory metals on their positions in the periodic system - alloys of tungsten with other refractory metals - sintering of the alloys - processing of the alloys - technological properties.

  15. Static magnets: what are they and what do they do?

    Directory of Open Access Journals (Sweden)

    L Laakso

    Full Text Available INTRODUCTION: Therapeutic static magnets have gained wide community acceptance for neuromusculoskeletal pain relief in many countries yet, apart from strong anecdotal reports of benefit, there is a paucity of scientific evidence for their use. OBJECTIVES: In this review we describe the physical characteristics of traditional and commonplace unipolar and bipolar static magnets as well as newer quadripolar magnetic arrays; discuss what is known of the physiological effects of static magnets and the strength of the literature; and make suggestions for targeted future research for static magnets in the management of neuromusculoskeletal pain conditions.

  16. Static model for a 3-DOF underactuated finger

    Directory of Open Access Journals (Sweden)

    F. Guay

    2011-02-01

    Full Text Available This paper introduces a static model of a three-degree-of-freedom underactuated finger. The model includes all static forces, namely actuation forces, return forces and gravity. All geometric and static parameters can be freely changed (pulley radius, member's mass, etc.. Hence, the model allows complete static simulations to be performed and it can also be used for numerical optimization.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  17. High-temperature Titanium Alloys

    Directory of Open Access Journals (Sweden)

    A.K. Gogia

    2005-04-01

    Full Text Available The development of high-temperature titanium alloys has contributed significantly to the spectacular progress in thrust-to-weight ratio of the aero gas turbines. This paper presents anoverview on the development of high-temperature titanium alloys used in aero engines and potential futuristic materials based on titanium aluminides and composites. The role of alloychemistry, processing, and microstructure, in determining the mechanical properties of titanium alloys is discussed. While phase equilibria and microstructural stability consideration haverestricted the use of conventional titanium alloys up to about 600 "C, alloys based on TiPl (or,, E,AINb (0, TiAl (y, and titaniumltitanium aluminides-based composites offer a possibility ofquantum jump in the temperature capability of titanium alloys.

  18. Multicomponent and High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Brian Cantor

    2014-08-01

    Full Text Available This paper describes some underlying principles of multicomponent and high entropy alloys, and gives some examples of these materials. Different types of multicomponent alloy and different methods of accessing multicomponent phase space are discussed. The alloys were manufactured by conventional and high speed solidification techniques, and their macroscopic, microscopic and nanoscale structures were studied by optical, X-ray and electron microscope methods. They exhibit a variety of amorphous, quasicrystalline, dendritic and eutectic structures.

  19. Porosity of porous Al alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two porosity models of porous Al alloys with different pore types (ball and polygon shape) were established. The experimental results coincide well with theoretical computations. The porosity of Al alloys (Prc) consists of three parts, porosity caused by preform particles (Prp), additional porosity (Pra), and porosity caused by solidification shrinkage (Prs). Prp is the main part of Prc while Pra is the key for fabricating porous Al alloys successfully in spite of its little contribution to Prc.

  20. Interatomic Potential to Simulate Radiation Damage in Fe-Cr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bonny, G.; Pasianot, R.; Terentyev, D.; Malerba, L.

    2011-03-15

    The report presents an Fe-Cr interatomic potential to model high-Cr ferritic alloys. The potential is fitted to thermodynamic and point-defect properties obtained from density functional theory (DFT) calculations and experiments. The developed potential is also benchmarked against other potentials available in literature. It shows particularly good agreement with the DFT obtained mixing enthalpy of the random alloy, the formation energy of intermetallics and experimental excess vibrational entropy and phase diagram. In addition, DFT calculated point-defect properties, both interstitial and substitutional, are well reproduced, as is the screw dislocation core structure. As a first validation of the potential, we study the precipitation hardening of Fe-Cr alloys via static simulations of the interaction between Cr precipitates and screw dislocations. It is concluded that the description of the dislocation core modification near a precipitate might have a significant influence on the interaction mechanisms observed in dynamic simulations.

  1. Thin wall ductile iron casting as a substitute for aluminum alloy casting in automotive industry

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-01-01

    Full Text Available In paper it is presented thin wall ductile iron casting (TWDI as a substitute of aluminium alloy casting. Upper control arm made of ductile iron with wall thickness ranging from 2 – 3.7 mm was produced by inmold process. Structure, mechanical properties and computer simulations were investigated. Structural analysis of TWDI shows pearlitic-ferritic matrix free from chills and porosity. Mechanical testing disclose superior ultimate tensile strength (Rm, yield strength (Rp0,2 and slightly lower elongation (E of TWDI in comparison with forged control arm made of aluminium alloy (6061-T6. Moreover results of computer simulation of static loading for tested control arms are presented. Analysis show that the light-weight ductile iron casting can be loaded to similar working conditions as the forged Al alloy without any potential failures.

  2. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    OpenAIRE

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance of a pile during the test conditions. - The integrity of a pile (pile integrity test). For the purposes of verification the design axial capacity and the static load – settlement behavior of piles...

  3. High-frequency magnetic characteristics of Fe-Co-based nanocrystalline alloy films

    Institute of Scientific and Technical Information of China (English)

    HIHARA; Takehiko; SUMIYAMA; Kenji

    2010-01-01

    Magnetically soft Fe-Co-based nanocrystalline alloy films were produced by two preparation methods:One using a new energetic cluster deposition technique and another using a conventional magnetron sputtering technique.Their structural,static magnetic properties and high-frequency magnetic characteristics were investigated.In the energetic cluster deposition method,by applying a high-bias voltage to a substrate,positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source,to form a high-density Fe-Co alloy cluster-assembled film with good high-frequency magnetic characteristics.In the conventional magnetron sputtering method,only by rotating substrate holder and without applying a static inducing magnetic field on the substrates,we produced Fe-Co-based nanocrystalline alloy films with a remarkable in-plane uniaxial magnetic anisotropy and a good soft magnetic property.The obtained Fe-Co-O,Fe-Co-Ti-N,and Fe-Co-Cr-N films all revealed a high real permeability exceeding 500 at a frequency up to 1.2 GHz.This makes Fe-Co-based nanocrystalline alloy films potential candidates as soft magnetic thin film materials for the high-frequency applications.

  4. Duct and cladding alloy

    Science.gov (United States)

    Korenko, Michael K.

    1983-01-01

    An austenitic alloy having good thermal stability and resistance to sodium corrosion at 700.degree. C. consists essentially of 35-45% nickel 7.5-14% chromium 0.8-3.2% molybdenum 0.3-1.0% silicon 0.2-1.0% manganese 0-0.1% zirconium 2.0-3.5% titanium 1.0-2.0% aluminum 0.02-0.1% carbon 0-0.01% boron and the balance iron.

  5. Analysis of laser alloyed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D.C.; Augustyniak, W.M.; Buene, L.; Draper, C.W.; Poate, J.M.

    1981-04-01

    Surface alloys of precious metals have many advantages over bulk alloys, the most obvious of which is cost reduction due to the reduced consumption of precious metal. There are several techniques for producing surface alloys. In this paper the laser irradiation technique is presented. The following lasers: CW CO/sub 2/, Q-switched Nd-YAG, frequency double Q-switched Nd-YAG, and pulsed ruby were used to irradiate and melt thin solid films of precious metals on metal substrates. This causes the surfaces to melt to a depth of approximately 10,000A. Alloying then takes place in the liquid phase where most metals are miscible. The high quench rates obtainable by this method of melting can result in the forming of metastable alloys. This melting and regrowth process is well understood and has been discussed in the literature over the last few years. This paper deals with two binary alloy systems, Au-Ni and Pd-Ti. Surface alloys of Au-Ni with a wide range of concentrations have been produced by laser irradiation of thin Au films on Ni. These films have been analyzed using Rutherford backscattering (RBS) and channeling. Many thin film metals other than Au have also been successfully alloyed using these methods. An example of a potential application is the laser surface alloying of Pd to Ti for corrosion passivation.

  6. 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.

  7. Oligocrystalline shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ueland, Stian M.; Chen, Ying; Schuh, Christopher A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2012-05-23

    Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture arising from transformation strain incompatibility at grain boundaries and triple junctions. Oligocrystalline shape memory alloys (oSMAs) are microstructurally designed SMA structures in which the total surface area exceeds the total grain boundary area, and triple junctions can even be completely absent. Here it is shown how an oligocrystalline structure provides a means of achieving single crystal-like SMA properties without being limited by constraints of single crystal processing. Additionally, the formation of oSMAs typically involves the reduction of the size scale of specimens, and sample size effects begin to emerge. Recent findings on a size effect on the martensitic transformation in oSMAs are compared and a new regime of heat transfer associated with the transformation heat evolution in these alloys is discussed. New results on unassisted two-way shape memory and the effect of loading rate in oSMAs are also reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Aluminum alloy impact sparkling

    Directory of Open Access Journals (Sweden)

    M. Dudyk

    2008-08-01

    Full Text Available The cast machine parts are widely used in many branches of industry. A very important issue is gaining the appropriate knowledge relating to the application of castings in places of explosion risks including but not limited to mining, chemical industry and rescue works. A possibility of explosion risks occurrence following the impact sparkling of the cast metal parts is still not solved problem in scientific research. In relation to this issue, in this article, the results of the study are presented, and relating to the tendency to impact sparkling of the aluminium alloys used in machine building. On the grounds of the results obtained, it was demonstrated that the registered impact sparkles bunches of feathers from the analyzed alloys: AlSi7Mg, (AK7; AlSi9Mg, (AK9; AlSi6Cu4, (AK64 and AlSi11, (AK11 show significant differences between each other. The quantitative analysis of the temperature distribution and nuclei surface area performed on the example of the alloy AK9 (subjected to defined period of corrosion allows for the statement that they are dangerous in conditions of explosion risk. Following this fact, designers and users of machine parts made from these materials should not use them in conditions where the explosive mixtures occur.

  9. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    Science.gov (United States)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2016-12-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  10. Fabrication of superhydrophobic nanostructured surface on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, R.; Farzaneh, M. [Universite du Quebec a Chicoutimi, Chicoutimi, QC (Canada)

    2011-01-15

    A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon registered) 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 ({proportional_to}164 ) and low contact angle hysteresis ({proportional_to}4 ). (orig.)

  11. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    Science.gov (United States)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2017-01-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  12. Investigation of Carbon incorporation into Al 6061 alloys

    Science.gov (United States)

    Ge, Xiaoxiao; Riba, Lourdes Salamanca; Wuttig, Manfred; Covetics Collaboration

    The incorporation of carbon nanostructures into aluminum alloys, such as Al6061 and Al7075, has the potential to further improve the mechanical, electrical and anti-corrosion properties of these alloys. We report on a novel method to incorporate up to 10.0 wt% carbon into the crystal structure of Al 6061 alloys to form a new material ``Al Covetics''. In this method, a DC current is applied to molten Al metal containing activated carbon particles. The current facilitates ionization of the carbon atoms and their bonding to each other, forming graphic chains and layers along preferential directions of the Al lattice. Raman mapping of the G and D peaks of graphitic carbon was used to confirm the role of the current in ensuring that the carbons remain in the metal by electro-static force and spread into the metal matrix evenly. Sp2 bonding of carbon was found all over the surface in the Covetics. Carbon signals were also observed everywhere in Covetics with Energy Dispersive X-ray Spectroscopy. However, localized carbon signals were detected in samples made with activated carbon but without applying any current. The dependence of the mechanical, electrical and structural properties of Al Covetics on C content from 3 to 10 wt. % will be presented.

  13. Radiation Effects in Refractory Alloys

    Science.gov (United States)

    Zinkle, Steven J.; Wiffen, F. W.

    2004-02-01

    In order to achieve the required low reactor mass per unit electrical power for space reactors, refractory alloys are essential due to their high operating temperature capability that in turn enables high thermal conversion efficiencies. One of the key issues associated with refractory alloys is their performance in a neutron irradiation environment. The available radiation effects data are reviewed for alloys based on Mo, W, Re, Nb and Ta. The largest database is associated with Mo alloys, whereas Re, W and Ta alloys have the least available information. Particular attention is focused on Nb-1Zr, which is a proposed cladding and structural material for the reactor in the Jupiter Icy Moons Orbiter (JIMO) project. All of the refractory alloys exhibit qualitatively similar temperature-dependent behavior. At low temperatures up to ~0.3TM, where TM is the melting temperature, the dominant effect of radiation is to produce pronounced radiation hardening and concomitant loss of ductility. The radiation hardening also causes a dramatic decrease in the fracture toughness of the refractory alloys. These low temperature radiation effects occur at relatively low damage levels of ~0.1 displacement per atom, dpa (~2×1024 n/m2, E>0.1 MeV). As a consequence, operation at low temperatures in the presence of neutron irradiation must be avoided for all refractory alloys. At intermediate temperatures (0.3 to 0.6 TM), void swelling and irradiation creep are the dominant effects of irradiation. The amount of volumetric swelling associated with void formation in refractory alloys is generally within engineering design limits (>10 dpa). Very little experimental data exist on irradiation creep of refractory alloys, but data for other body centered cubic alloys suggest that the irradiation creep will produce negligible deformation for near-term space reactor applications.

  14. CONTINUOUS PRODUCTION OF HYDROXYPROPYL STARCH IN A STATIC MIXER REACTOR

    NARCIS (Netherlands)

    LAMMERS, G; STAMHUIS, EJ; BEENACKERS, AACM

    1993-01-01

    A novel type of reactor for the chemical derivatization of starch pastes is presented. The design is based on the application of static mixers. The reactor shows excellent plug flow behaviour with a Peclet number of about 100. The viscosity behaviour of concentrated starch pastes in the static mixer

  15. Theory of static and dynamic properties of Gd

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1986-01-01

    Gadolinium is a Heisenberg magnet intermediate between the localized EuO and the itinerant Fe and Ni. The authors develop a correlation theory for Gd and calculate self-consistently both static and dynamic properties. One finds that the high frequency spin waves persist for T>Tc. The static...

  16. Static energy meter errors caused by conducted electromagnetic interference

    NARCIS (Netherlands)

    Leferink, Frank; Keyer, Cees; Melentjev, Anton

    2017-01-01

    Static, or electronic, energy meters are replacing the conventional electromechanical meters. Consumers are some-times complaining about higher energy readings and billing after the change to a static meter, but there is not a clear common or root cause at present. Electromagnetic interference has b

  17. Instructional Animation versus Static Pictures: A Meta-Analysis

    Science.gov (United States)

    Hoffler, Tim N.; Leutner, Detlev

    2007-01-01

    A meta-analysis of 26 primary studies, yielding 76 pair-wise comparisons of dynamic and static visualizations, reveals a medium-sized overall advantage of instructional animations over static pictures. The mean weighted effect size on learning outcome is d = 0.37 (95% CI 0.25-0.49). Moderator analyses indicate even more substantial effect sizes…

  18. 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…

  19. 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...

  20. 49 CFR 238.405 - Longitudinal static compressive strength.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Longitudinal static compressive strength. 238.405 Section 238.405 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... II Passenger Equipment § 238.405 Longitudinal static compressive strength. (a) To form an...

  1. Non-static vacuum strings: exterior and interior solutions

    Energy Technology Data Exchange (ETDEWEB)

    Stein-Schabes, J.A.

    1986-01-01

    New non-static cylindrically symmetric solutions of Einsteins's equations are presented. Some of these solutions represent string-like objects. An exterior vacuum solution is matched to a non-vacuum interior solution for different forms of the energy-momentum tensor. They generalize the standard static string. 12 refs.

  2. The Active-Static Nature of Amuzgo (Otomanguean).

    Science.gov (United States)

    Stark, Thomas C. Smith; Garcia, Fermin Tapia

    An analysis of Amuzgo, a language within the Otomanguean family of Mexico, suggests that it is an active-static language with patterns similar but not parallel to those of Chocho. In the report, data on the characteristics of Chocho are summarized, theory and research on active-static languages is reviewed, and the data on Amuzgo are presented.…

  3. Integrable cases of gravitating static isothermal fluid spheres

    CERN Document Server

    Ivanov, B V

    2002-01-01

    It is shown that different approaches towards the solution of the Einstein equations for a static spherically symmetric perfect fluid with a gamma-law equation of state lead to an Abel differential equation of the second kind. Its only integrable cases at present are flat spacetime, de Sitter solution and its Buchdahl transform, Einstein static universe and the Klein-Tolman solution.

  4. Comparative statics of games between relatives.

    Science.gov (United States)

    Milchtaich, Igal

    2006-03-01

    According to Hamilton's theory of kin selection, species tend to evolve behavior such that each organism appears to be attempting to maximize its inclusive fitness. In particular, two neighbors are likely to help each other if the cost of doing so is less than the benefit multiplied by r, their coefficient of relatedness. Since the latter is less than unity, mutual altruism benefits both neighbors. However, is it theoretically possible that acting so as to maximize the inclusive, rather than personal, fitness may harm both parties. This may occur in strategic symmetric pairwise interactions (more specifically, nxn games), in which the outcome depends on both sides' actions. In this case, the equilibrium outcome may be less favorable to the interactants' personal fitness than if each of them acted so as to maximize the latter. This paper shows, however, that such negative effect of relatedness on fitness is incompatible with evolutionary stability. If the symmetric equilibrium strategies are evolutionarily stable, a higher coefficient of relatedness can only entail higher personal fitness for the two neighbors. This suggests that negative comparative statics as above are not likely to occur in nature.

  5. Scalar Static Polarizabilities of Lanthanides and Actinides

    CERN Document Server

    Dzuba, V A; Flambaum, V V

    2014-01-01

    We calculate scalar static polarizabilities for lanthanides and actinides, the atoms with open $4f$ or $5f$ subshell. We show that polarizabilities of the low states are approximately the same for all states of given configuration and present a way of calculating them reducing valence space to just two or three valence electrons occupying $6s$ and $5d$ states for lanthanides or $7s$ and $6d$ states for actinides while $4f$ and $5f$ states are considered to be in the core. Configuration interaction technique is used to calculate polarizabilities of lanthanides and actinides for all states of the $4f^n6s^2$ and $4f^{n-1}6s^25d$ configurations of lanthanides and all states of the $5f^{n}7s^2$ and $5f^{n-1}7s^26d$ configurations of actinides. Polarizability of the electron core (including f-orbitals) has been calculated in the RPA approximation.

  6. Preservation of Laboratory Instruments in Static Storage

    Energy Technology Data Exchange (ETDEWEB)

    Gregg, J. L.; Shackelford, M. A.

    1950-02-22

    It is desirable to place laboratory instruments in static storage so that they may be put into operation with only normal servicing. Such instruments may be subject to many forms of deterioration. There may be deterioration of metal parts due to chemical and electrolytic corrosion and the effects of moisture, excessive dryness, and microorganisms, i.e., mildew on organic parts. To preserve such instruments without disassembly or troublesome surface coatings, requires methods that will remove the major cause of deterioration - that is, excessive humidity, by reducing and maintaining the relative humidity of the air surrounding the item at 30 per cent or less. It is also necessary to eliminate or separate hygroscopic materials from the item since they will cause corrosion, by surface adsorption and condensation, even though a dry atmosphere is maintained. The methods and materials used must not only be efficient and economical but also require a minimun of maintenance, Protection against physical damage and temperature extremes is dependent upon the storage site and is not considered in this report.

  7. 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.

  8. 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.

  9. Liquid methanol under a static electric field

    Energy Technology Data Exchange (ETDEWEB)

    Cassone, Giuseppe, E-mail: giuseppe.cassone@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France); Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Giaquinta, Paolo V., E-mail: paolo.giaquinta@unime.it [Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); Saija, Franz, E-mail: saija@ipcf.cnr.it [CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Saitta, A. Marco, E-mail: marco.saitta@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France)

    2015-02-07

    We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

  10. Non static cosmic strings in Lyra geometry

    CERN Document Server

    Rahaman, Farook

    2007-01-01

    The gravitational field of both local and global non static cosmic strings in the context of Lyra geometry are investigated. Local strings are characterized by having an energy momentum tensor whose only non null components are $T_{tt} = T_{zz}$ . As linearized Einstein equations are formally analogous to the Maxwell equations, the exterior solution does not depend on the radial distribution of the source and hence a Dirac d function was used to approximate the radial distribution of the energy momentum tensor for a local cosmic string along the z-axis: $T_{ab} = \\delta(x) \\delta(y)diag (\\sigma, 0, 0, \\sigma) $, $\\sigma $being the energy density of the string [A.Vilenkin. Phys.Rep.(1985)121,263]. For a global string, the energy momentum tensor components are calculated from the action density for a complex scalar field y along with a Maxican hat potential. The gravitational field of the global string is shown to be attractive in nature.

  11. Properties of laser alloyed surface layers on magnesium base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Galun, R.; Weisheit, A.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. fuer Werkstoffkunde und Werkstofftechnik)

    1998-01-01

    The investigations have shown that laser surface alloying is a promising process to improve the wear and corrosion properties of magnesium base alloys without affecting the initial bulk properties like the low density. With an alloying element combination of aluminium and nickel the wear rate in the scratch test was reduced by 90% compared to untreated pure magnesium. Additionally the corrosion resistance was improved by laser alloying with this element combination. Because of distortion or crack formation in the case of large area treatments, the laser alloying should be limited to the treatment of smaller areas. In the near future this process could be an interesting alternative to surface coating or to a partially reinforcement with ceramic fibres or particles. (orig.)

  12. 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...

  13. Electron Theory in Alloy Design

    CERN Document Server

    Pettifor, DG

    1992-01-01

    Presents recent developments in electron theory which have impacted upon the search for novel alloys with improved mechanical or magnetic properties. The ten chapters outline the ability of electron theory to make quantitative predictions (such as heats of formation, planar fault energies, shear moduli and magnetic anisotropy), and to provide simplifying concepts for understanding trends in alloy behaviour.

  14. Shape memory alloy thaw sensors

    Science.gov (United States)

    Shahinpoor, Mohsen; Martinez, David R.

    1998-01-01

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

  15. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    NARCIS (Netherlands)

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance

  16. Mo-Si alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  17. Influence of Friction Stir Welding (FSW) on Mechanical and Corrosion Properties of AW-7020M and Aw-7020 Alloys

    OpenAIRE

    Dudzik Krzysztof; Jurczak Wojciech

    2016-01-01

    Friction welding associated with mixing the weld material (FSW - Friction Stir Welding ) is an alternative to MIG and TIG welding techniques for Al-alloys. This paper presents experimental results obtained from static tension tests on specimens made of AW-7020M and AW-7020 alloys and their joints welded by using FSW method carried out on flat specimens, according to Polish standards : PN-EN ISO 4136:2011 and PN-EN ISO 6892-1:2010. Results of corrosion resistance tests are also presented. The ...

  18. Wedlable nickel aluminide alloy

    Energy Technology Data Exchange (ETDEWEB)

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    2002-11-19

    A Ni.sub.3 Al alloy with improved weldability is described. It contains about 6-12 wt % Al, about 6-12 wt % Cr, about 0-3 wt % Mo, about 1.5-6 wt % Zr, about 0-0.02 wt % B and at least one of about 0-0.15 wt % C, about 0-0.20 wt % Si, about 0-0.01 wt % S and about 0-0.30 wt % Fe with the balance being Ni.

  19. Effects of static magnetic field on mutagenesis in in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ikehata, M; Yoshie, S; Hayakawa, T [Railway Technical Research Institute, Kokubunji, Tokyo 185-8540 (Japan); Hirota, N [Nano Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 277-8561 (Japan)], E-mail: ikehata@rtri.or.jp

    2009-03-01

    Effects of static magnetic field up to 13 T were estimated in Escherichia coli and Saccharomyces cerevisiae. We observed that exposure to a 5 T static magnetic field resulted in a slight but significant increase in gene recombination frequency while frequency of reverse point mutation was not altered in S. cerevisiae. This mutagenic effect showed a dose response relationship as J-shape. To investigate an involvement of reactive oxygen species in possible mutagenic effect of static magnetic field, SOD deficient E. coli QC774 was used in thymine synthesis-based mutation assay. The result shows that static magnetic field up to 13 T did not indicate mutagenicity. Thus, it is suggested that frequency of point mutation does not changed under static magnetic field regardless of its susceptibility to superoxide. These results suggest that strong static magnetic field would have small but detectable mutagenic potential. Although mechanism of the mutagenic effect of static magnetic field has not been elucidated yet, the extent of this effect is estimated extremely small by comparison with other mutagens such as ultraviolet irradiation.

  20. 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.

  1. Galvanic cells including cobalt-chromium alloys.

    Science.gov (United States)

    Gjerdet, N R

    1980-01-01

    Galvanic cells may be created when dentures made of cobalt-chromium alloys are placed on teeth with metallic restorations. The power of such cells was evaluated in an in vitro galvanic using amalgams, gold alloy, and nickel-chromium alloys. The amalgams and one of the nickel-chromium alloys revealed high corrosion currents when placed in contact with cobalt-chromium alloy, the conventional amalgam showing the highest values. The gold alloy and another nickel-chromium alloy exhibited low corrosion currents and they were noble with respect to cobalt-chromium.

  2. Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

    Energy Technology Data Exchange (ETDEWEB)

    Xu Jiang; Zhuo Chengzhi; Tao Jie; Liu Linlin [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); Jiang Shuyun [Department of Mechanical Engineering, Southeast University, 2 Sipailou, Nanjing 210096 (China)], E-mail: xujiang73@nuaa.edu.cn

    2009-01-07

    In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO{sub 2} predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 deg. C) conditions, amorphous nano-SiO{sub 2} particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr{sub 6.5}Ni{sub 2.5}Si and Cr{sub 23}C{sub 6}. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO{sub 2} particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO{sub 2} particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO{sub 2} particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix

  3. THERMODYNAMICS AND KINETICS OF PHASE TRANSFORMATIONS IN PLUTONIUM ALLOYS - PART I

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, P A; Kaufman, L; Liu, Z; Zhou, S

    2004-08-18

    In this report we investigate order, stability, and phase transformations for a series of actinide-based alloys. The statics and kinetics of precipitation and ordering in this class of alloys are modeled with a scheme that couples fundamental information on the alloy energetics obtained from experimental and assessed thermo-chemical data to the CALPHAD approach commonly used in industry for designing alloys with engineering specificity with the help of the Thermo-Calc software application. The CALPHAD approach is applied to the study of the equilibrium thermodynamic properties of Pu-based alloys, Pu-X, where X=Al, Fe, Ga. The assessment of the equilibrium phase diagrams in the whole range of alloy composition has been performed with the PARROT module of the Thermo-Calc application software. Predictions are made on the low temperature and Pu-rich side of the phase diagrams of Pu-Ga and Pu-Al for which controversy has been noted in the past. The validity of the assessed thermo-chemical database will be discussed by comparing predicted heats of transformation for pure Pu with measured values from differential scanning calorimetry analysis. An overall picture for the stability properties of Pu-Ga and Pu-Al that reconciles the results of past studies carried out on these alloys is proposed. Results on phase stability in the ternary Fe-Ga-Pu and Al-Fe-Pu alloys are discussed. The information collected in this study is then used to model metastability, long-term stability and aging for this class of alloys by coupling Thermo-Calc with DICTRA, a series of modules that allow the analysis of DIffusion Controlled TRAnsformations. Kinetics information is then summarized in so-called TTT (temperature-time-transformations) diagrams for the most relevant phases of actinide alloys. Specifically, results are presented on kinetics of phase transformations associated with the eutectoid-phase decomposition reaction occurring at low temperature, and with the martensitic transformation

  4. Axisymmetric Natural Frequencies of Statically Loaded Annular Plates

    Directory of Open Access Journals (Sweden)

    Eihab M. Abdel-Rahman

    2003-01-01

    Full Text Available We present a numerical procedure to solve the axisymmetric vibration problem of statically loaded annular plates. We use the von Kármán nonlinear plate model to account for large deformations and study the effect of static deflections on the natural frequencies and mode shapes for six combinations of boundary conditions. The shooting method is used to solve the resulting eigenvalue problem. Our results show that static deformations have a significant effect on the natural frequencies and small effect on the mode shapes of the plate. Further, the results show that the presence of in-plane stresses has a significant effect on the natural frequencies.

  5. 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.

  6. An eigen theory of static electromagnetic field for anisotropic media

    Institute of Scientific and Technical Information of China (English)

    Shao-hua GUO

    2009-01-01

    Static electromagnetic fields are studied based on standard spaces of the physical presentation,and the modal equations of static electromagnetic fields for anisotropic media are derived. By introducing a new set of first-order potential functions,several novel theoretical results are obtained. It is found that,for isotropic media,electric or magnetic potentials are scalar; while for anisotropic media,they are vectors. Magnitude and direction of the vector potentials are related to the anisotropic subspaces. Based on these results,we discuss the laws of static electromagnetic fields for anisotropic media.

  7. 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.

  8. Another look at Statics and Dynamics of Switching Power Converters

    Science.gov (United States)

    Sasaki, Seigo; Watanabe, Haruo

    Three types of switching power supply, which are buck, boost, buck/boost converter, are statically and dynamically analysed. A framework of large signal analysis presents characteristics of converters which vary with operating points, and discusses a relationship between statics and dynamics. It is shown that boost and buck/boost converters substantially change their characteristics. There exists the operating points where for low frequencies the phases become -90° or -180° and the gains fall off to low values. The phenomenon is characterized by a zero of transfer function of the converter and also by the statics.

  9. QUASI-STATIC ANALYSIS FOR VISCOELASTIC TIMOSHENKO BEAMS WITH DAMAGE

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams, the equations governing quasi-static and dynamical behavior of Timoshenko beams with damage were first derived. The quasi-static behavior of the viscoelastic Timoshenko beam under step loading was analyzed and the analytical solution was obtained in the Laplace transformation domain. The deflection and damage curves at different time were obtained by using the numerical inverse transform and the influences of material parameters on the quasi-static behavior of the beam were investigated in detail.

  10. Corrosion behavior of dental alloys used for retention elements in prosthodontics.

    Science.gov (United States)

    Nierlich, Judith; Papageorgiou, Spyridon N; Bourauel, Christoph; Hültenschmidt, Robert; Bayer, Stefan; Stark, Helmut; Keilig, Ludger

    2016-06-01

    The purpose of this study was to investigate the corrosion behavior of 10 different high noble gold-based dental alloys, used for prosthodontic retention elements, according to ISO 10271. Samples of 10 high-noble and noble gold-based dental alloys were subjected to: (i) static immersion tests with subsequent analysis of ion release for eight different elements using mass spectrometry; (ii) electrochemical tests, including open-circuit potential and potentiodynamic scans; and (iii) scanning electron microscopy, followed by energy-dispersive X-ray microscopy. The results were analyzed using one-way ANOVA and Sidak multiple-comparisons post-hoc test at a level of significance of α = 0.05. Significant differences were found among the 10 alloys studied for all ions (P potential and from 566.7 to 1367.5 mV for the breakdown potential. Both the open-circuit and the breakdown potential varied considerably among these alloys. Scanning electron microscopy analysis confirmed the existence of typically small-diameter corrosion defects, whilst the energy-dispersive X-ray analysis found no significant alteration in the elemental composition of the alloys. The results of this study reveal the variability in the corrosive resistance among the materials used for retention elements in prosthodontics.

  11. [Prosthetic dental alloys. 1].

    Science.gov (United States)

    Quintero Engelmbright, M A

    1990-11-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements.

  12. [Prosthetic dental alloys (2)].

    Science.gov (United States)

    Quintero Englembright, M A

    1990-12-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements.

  13. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  14. Effects of segregation of primary alloying elements on the creep response in magnesium alloys

    DEFF Research Database (Denmark)

    Huang, Y.D.; Dieringa, H.; Hort, N.

    2008-01-01

    The segregation of primary alloying elements deteriorates the high temperature creep resistance of magnesium alloys. Annealing at high temperatures alleviating their segregations can improve the creep resistance. Present investigation on the effect of segregation of primary alloying elements...

  15. Mechanically Alloyed High Entropy Composite

    Science.gov (United States)

    Popescu, G.; Adrian, M. M.; Csaki, I.; Popescu, C. A.; Mitrică, D.; Vasile, S.; Carcea, I.

    2016-08-01

    In the last years high entropy alloys have been investigated due to their high hardness, high temperature stability and unusual properties that make these alloys to have significant interest. In comparison with traditional alloys that are based on two or three major elements, this new generation alloys consists at least of 5 principal elements, with the concentration between 5 and 35 at.%. The present paper reports synthesis of high entropy alloys (HEA) and high entropy composites (HEC) synthesized by mechanical alloying (MA). The equiatomic AlCrFeNiMn matrix was used for creating the HEA matrix, starting from elemental powders and as reinforcing material for composites was used pure graphite. The mechanical alloying process was carried out at different duration, in a high energy planetary ball mill, under argon atmosphere. The elemental powders alloying began after '5 hours of milling and was complete after 40 hours. The mechanical alloyed matrix and composite was pressed and heat treated under argon protection. The elemental powers were investigated for physical - technological properties, and by X-ray diffraction and scanning electron microscopy. Phase pressing operation was realized with a hydraulic press and the applied pressure was progressive. The sintering process was carried out at 850°C for 2 h. The X-ray diffraction revealed that the MA process resulted in solid solutions formation and also revealed body- centred cubic (BCC) and face-centred cubic (FCC) structures with average grain size around 40 nm. In addition, nanoscale particles were highlighted by scanning electron microscopy, as well as the homogeneity of the chemical composition of the matrix and composite that was confirmed by EDX microanalysis. It was noted that HEA matrix and HEA composites were processed with a high degree of compaction and with a quite large capacity of mixed powder densification (around 70%).

  16. Modeling dissolution in aluminum alloys

    Science.gov (United States)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  17. Alloying and Casting Furnace for Shape Memory Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The concept in the proposed project is to create a melting, alloying and casting furnace for the processing titanium based SMA using cold crucible techniques. The...

  18. Alloy design for intrinsically ductile refractory high-entropy alloys

    Science.gov (United States)

    Sheikh, Saad; Shafeie, Samrand; Hu, Qiang; Ahlström, Johan; Persson, Christer; Veselý, Jaroslav; Zýka, Jiří; Klement, Uta; Guo, Sheng

    2016-10-01

    Refractory high-entropy alloys (RHEAs), comprising group IV (Ti, Zr, Hf), V (V, Nb, Ta), and VI (Cr, Mo, W) refractory elements, can be potentially new generation high-temperature materials. However, most existing RHEAs lack room-temperature ductility, similar to conventional refractory metals and alloys. Here, we propose an alloy design strategy to intrinsically ductilize RHEAs based on the electron theory and more specifically to decrease the number of valence electrons through controlled alloying. A new ductile RHEA, Hf0.5Nb0.5Ta0.5Ti1.5Zr, was developed as a proof of concept, with a fracture stress of close to 1 GPa and an elongation of near 20%. The findings here will shed light on the development of ductile RHEAs for ultrahigh-temperature applications in aerospace and power-generation industries.

  19. 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...

  20. Person Identification System using Static-dynamic signatures fusion

    Directory of Open Access Journals (Sweden)

    S.A Daramola

    2010-09-01

    Full Text Available Off-line signature verification systems rely on static image of signature for person identification. Imposter can easily imitate the static image of signature of the genuine user due to lack of dynamic features. This paper proposes person identity verification system using fused static-dynamic signature features. Computational efficient technique is developed to extract and fuse static and dynamic features extracted from offline and online signatures of the same person. The training stage used the fused features to generate couple reference data and classification stage compared the couple test signatures with the reference data based on the set threshold values. The system performance is encouraging against imposter attacker in comparison with previous single sensor offline signature identification systems.