The Experts below are selected from a list of 1059 Experts worldwide ranked by ideXlab platform
Zhifeng Huang - One of the best experts on this subject based on the ideXlab platform.
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uncovering the influence of common nonmetallic impurities on the stability and strength of a σ5 310 grain boundary in cu
Acta Materialia, 2018Co-Authors: Zhifeng Huang, Fei Chen, Qiang Shen, Lianmeng Zhang, Timothy J RupertAbstract:Abstract Impurities are often driven to segregate to grain boundaries, which can significantly alter a material's thermal stability and mechanical behavior. To provide a comprehensive picture of this issue, the influence of a wide variety of common nonmetallic impurities (H, B, C, N, O, Si, P and S) incorporated during service or materials processing are studied using first-principles simulations, with a focus on identifying changes to the energetics and mechanical strength of a Cu Σ5 (310) grain boundary. Changes to the grain boundary energy are found to be closely correlated with the Covalent radii of the impurities and the volumetric deformations of polyhedra at the interface. The strengthening energies of each impurity are evaluated as a function of Covalent Radius and electronegativity, followed by first-principles-based tensile tests on selected impurities. The strengthening of a B-doped grain boundary comes from an enhancement of the charge density among the adjacent Cu atoms, which improves the connection between the two grains. Alternatively, the detrimental effect of O results from the reduction of interactions between the Cu atoms. This work deepens the understanding of the possible beneficial and harmful effects of impurities on grain boundaries, providing a guide for materials processing studies.
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uncovering the influence of common nonmetal impurities on the stability and strength of a sigma 5 310 grain boundary in cu
arXiv: Materials Science, 2017Co-Authors: Zhifeng Huang, Fei Chen, Qiang Shen, Lianmeng Zhang, Timothy J RupertAbstract:Impurities are often driven to segregate to grain boundaries, which can significantly alter a material's thermal stability and mechanical behavior. To provide a comprehensive picture of this issue, the influence of a wide variety of common nonmetal impurities (H, B, C, N, O, Si, P and S) incorporated during service or materials processing are studied using first-principles simulations, with a focus on identifying changes to the energetics and mechanical strength of a Cu $\Sigma$5 (310) grain boundary. Changes to the grain boundary energy are found to be closely correlated with the Covalent radii of the impurities and the volumetric deformations of polyhedra at the interface. The strengthening energies of each impurity are evaluated as a function of Covalent Radius and electronegativity, followed by first-principles-based tensile tests on selected impurities. The strengthening of a B-doped grain boundary comes from an enhancement of the charge density among the adjacent Cu atoms, which improves the connection between the two grains. Alternatively, the detrimental effect of O results from the reduction of charge density between the Cu atoms. This work deepens the understanding of the possible beneficial and harmful effects of impurities on grain boundaries, providing a guide for materials processing studies.
Timothy J Rupert - One of the best experts on this subject based on the ideXlab platform.
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uncovering the influence of common nonmetallic impurities on the stability and strength of a σ5 310 grain boundary in cu
Acta Materialia, 2018Co-Authors: Zhifeng Huang, Fei Chen, Qiang Shen, Lianmeng Zhang, Timothy J RupertAbstract:Abstract Impurities are often driven to segregate to grain boundaries, which can significantly alter a material's thermal stability and mechanical behavior. To provide a comprehensive picture of this issue, the influence of a wide variety of common nonmetallic impurities (H, B, C, N, O, Si, P and S) incorporated during service or materials processing are studied using first-principles simulations, with a focus on identifying changes to the energetics and mechanical strength of a Cu Σ5 (310) grain boundary. Changes to the grain boundary energy are found to be closely correlated with the Covalent radii of the impurities and the volumetric deformations of polyhedra at the interface. The strengthening energies of each impurity are evaluated as a function of Covalent Radius and electronegativity, followed by first-principles-based tensile tests on selected impurities. The strengthening of a B-doped grain boundary comes from an enhancement of the charge density among the adjacent Cu atoms, which improves the connection between the two grains. Alternatively, the detrimental effect of O results from the reduction of interactions between the Cu atoms. This work deepens the understanding of the possible beneficial and harmful effects of impurities on grain boundaries, providing a guide for materials processing studies.
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uncovering the influence of common nonmetal impurities on the stability and strength of a sigma 5 310 grain boundary in cu
arXiv: Materials Science, 2017Co-Authors: Zhifeng Huang, Fei Chen, Qiang Shen, Lianmeng Zhang, Timothy J RupertAbstract:Impurities are often driven to segregate to grain boundaries, which can significantly alter a material's thermal stability and mechanical behavior. To provide a comprehensive picture of this issue, the influence of a wide variety of common nonmetal impurities (H, B, C, N, O, Si, P and S) incorporated during service or materials processing are studied using first-principles simulations, with a focus on identifying changes to the energetics and mechanical strength of a Cu $\Sigma$5 (310) grain boundary. Changes to the grain boundary energy are found to be closely correlated with the Covalent radii of the impurities and the volumetric deformations of polyhedra at the interface. The strengthening energies of each impurity are evaluated as a function of Covalent Radius and electronegativity, followed by first-principles-based tensile tests on selected impurities. The strengthening of a B-doped grain boundary comes from an enhancement of the charge density among the adjacent Cu atoms, which improves the connection between the two grains. Alternatively, the detrimental effect of O results from the reduction of charge density between the Cu atoms. This work deepens the understanding of the possible beneficial and harmful effects of impurities on grain boundaries, providing a guide for materials processing studies.
J Mutus - One of the best experts on this subject based on the ideXlab platform.
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Low Energy Electron Point Projection Microscopy of Suspended Graphene, the Ultimate “Microscope Slide”
2013Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R UrbanAbstract:Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the Covalent Radius of sp2-bonded carbon. Also observed is rip-pling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 ± 0.6A ̊ for the electron emitter. It is demonstrated that graphene can serve as both anode and substrate in PPM, thereby avoiding distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography. 1 a
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low energy electron point projection microscopy of suspended graphene the ultimate microscope slide
New Journal of Physics, 2011Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R Urban, Mark Salomons, Martin CloutierAbstract:Point projection microscopy (PPM) is used to image suspended graphene by using low-energy electrons (100–205 eV). Because of the low energies used, the graphene is neither damaged nor contaminated by the electron beam for doses of the order of 107 electrons per nm2. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet twice as thick as the Covalent Radius of sp2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to diffraction off the edge of a graphene knife edge is observed and is used to calculate a virtual source size of 4.7±0.6 A for the electron emitter. It is demonstrated that graphene can serve as both the anode and the substrate in PPM, thereby avoiding distortions due to strong field gradients around nanoscale objects. Graphene can be used to image objects suspended on the sheet using PPM and, in the future, electron holography.
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low energy electron point projection microscopy of suspended graphene the ultimate microscope slide
arXiv: Mesoscale and Nanoscale Physics, 2011Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R Urban, Mark Salomons, Martin Cloutier, Paul E Sheehan, Robert A WolkowAbstract:Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the Covalent Radius of sp^2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 +/- 0.6 Angstroms for the electron emitter. It is demonstrated that graphene can be used as both anode and substrate in PPM in order to avoid distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography.
R Urban - One of the best experts on this subject based on the ideXlab platform.
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Low Energy Electron Point Projection Microscopy of Suspended Graphene, the Ultimate “Microscope Slide”
2013Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R UrbanAbstract:Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the Covalent Radius of sp2-bonded carbon. Also observed is rip-pling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 ± 0.6A ̊ for the electron emitter. It is demonstrated that graphene can serve as both anode and substrate in PPM, thereby avoiding distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography. 1 a
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low energy electron point projection microscopy of suspended graphene the ultimate microscope slide
New Journal of Physics, 2011Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R Urban, Mark Salomons, Martin CloutierAbstract:Point projection microscopy (PPM) is used to image suspended graphene by using low-energy electrons (100–205 eV). Because of the low energies used, the graphene is neither damaged nor contaminated by the electron beam for doses of the order of 107 electrons per nm2. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet twice as thick as the Covalent Radius of sp2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to diffraction off the edge of a graphene knife edge is observed and is used to calculate a virtual source size of 4.7±0.6 A for the electron emitter. It is demonstrated that graphene can serve as both the anode and the substrate in PPM, thereby avoiding distortions due to strong field gradients around nanoscale objects. Graphene can be used to image objects suspended on the sheet using PPM and, in the future, electron holography.
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low energy electron point projection microscopy of suspended graphene the ultimate microscope slide
arXiv: Mesoscale and Nanoscale Physics, 2011Co-Authors: J Mutus, L Livadaru, Jeremy T Robinson, R Urban, Mark Salomons, Martin Cloutier, Paul E Sheehan, Robert A WolkowAbstract:Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the Covalent Radius of sp^2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 +/- 0.6 Angstroms for the electron emitter. It is demonstrated that graphene can be used as both anode and substrate in PPM in order to avoid distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography.
Norihisa Tatarazako - One of the best experts on this subject based on the ideXlab platform.
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Chronic toxicity of 50 metals to Ceriodaphnia dubia.
Journal of applied toxicology : JAT, 2020Co-Authors: Akira Okamoto, Shigeki Masunaga, Norihisa TatarazakoAbstract:Metals are essential elements for human life but may cause disorders when exposure is excessive. Previously, we reported on the acute toxicity of 50 metals; however, the chronic toxicity data of some metals are not available. Therefore, we conducted chronic toxicity tests to determine the effects of 50 metals on the water flea, Ceriodaphnia dubia. The IC20 of 20 metals (Be, Sc, Cr, Co, Ni, Cu, Zn, Y, Ru, Ag, Cd, In, Te, W, Os, Pt, Au, Hg, Tl and Pb) were 100 000 μg/L. Three metals (Pd, Hf and Ta) did not show IC20 at the upper limit of respective aqueous solubility, and IC20 s were not obtained. The maximum test concentrations (almost aqueous solubility) of Pd, Hf and Ta were 83, 2400 and 5.3 μg/L, respectively. These data show the high correlation between our IC50 s for C. dubia and those for Dahpnia magna published previously. The IC50 s of 47 metals were not correlated with electronegativity, first ionization energy, atomic weight, atomic number, Covalent Radius, atomic Radius or ionic Radius.
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acute toxicity of 50 metals to daphnia magna
Journal of Applied Toxicology, 2015Co-Authors: Akira Okamoto, Norihisa Tatarazako, Masumi YamamuroAbstract:Metals are essential for human life and physiological functions but may sometimes cause disorders. Therefore, we conducted acute toxicity testing of 50 metals in Daphnia magna: EC50s of seven elements (Be, Cu, Ag, Cd, Os, Au and Hg) were 100,000 μgl 1 ; and. 7 elements (Ti, Zr, Bi, Nb, Hf, Re and Ta) did not show EC50 at the upper limit of respective aqueous solubility, and EC50s were not obtained. Ga, Ru and Pd adhered to the body of D. magna and physically retarded the movement of D. magna. These metals formed hydroxides after adjusting the pH. Therefore, here, we distinguished this physical effect from the physiological toxic effect. The acute toxicity results of 40 elements obtained in this study were not correlated with electronegativity. Similarly, the acute toxicity results of metals including the rare metals were also not correlated with first ionization energy, atomic weight, atomic number, Covalent Radius, atomic Radius or ionic Radius. Copyright © 2014 John Wiley & Sons, Ltd.
