The Experts below are selected from a list of 7725 Experts worldwide ranked by ideXlab platform
Todd R Engstrom - One of the best experts on this subject based on the ideXlab platform.
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material ii diffusion limited kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R EngstromAbstract:The adsorption, desorption, and diffusion kinetics of N2 on thick (up to ∼9μm) porous films of amorphous solid water (ASW) films were studied using molecular beam techniques and temperature programmed desorption. Porous ASW films were grown on Pt(111) at low temperature ( 1μm), N2 adsorption at 27K results in a nonuniform distribution, where most of N2 is trapped in the outer region of the film. Redistribution of N2 can be induced by thermal annealing. The apparent activation energy for this process is ∼7kJ∕mol, which is approximately half of the desorption activation energy at the corresponding coverage. Preadsorption of Kr preferentially adsorbs onto the highest energy binding sites, thereby preventing N2 from trapping in the outer region of the film which facilitates N2 transport de...
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material i surface limited desorption kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R EngstromAbstract:The adsorption and desorption kinetics of N2 on porous amorphous solid water (ASW) films were studied using molecular beam techniques, temperature programed desorption (TPD), and reflection-absorption infrared spectroscopy. The ASW films were grown on Pt(111) at 23K by ballistic deposition from a collimated H2O beam at various incident angles to control the film porosity. The experimental results show that the N2 condensation coefficient is essentially unity until near saturation, independent of the ASW film thickness indicating that N2 transport within the porous films is rapid. The TPD results show that the desorption of a fixed dose of N2 shifts to higher temperature with ASW film thickness. Kinetic analysis of the TPD spectra shows that a film thickness rescaling of the coverage-dependent activation energy curve results in a single master curve. Simulation of the TPD spectra using this master curve results in a quantitative fit to the experiments over a wide range of ASW thicknesses (up to 1000 layers...
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material i surface limited desorption kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R Engstrom, Bruce D KayAbstract:The adsorption and desorption kinetics of N2 on porous amorphous solid water (ASW) films were studied using molecular beam techniques, temperature programed desorption (TPD), and reflection-absorption infrared spectroscopy. The ASW films were grown on Pt(111) at 23 K by ballistic deposition from a collimated H2O beam at various incident angles to control the film porosity. The experimental results show that the N2 condensation coefficient is essentially unity until near saturation, independent of the ASW film thickness indicating that N2 transport within the porous films is rapid. The TPD results show that the desorption of a fixed dose of N2 shifts to higher temperature with ASW film thickness. Kinetic analysis of the TPD spectra shows that a film thickness rescaling of the coverage-dependent activation energy curve results in a single master curve. Simulation of the TPD spectra using this master curve results in a quantitative fit to the experiments over a wide range of ASW thicknesses (up to 1000 layers, approximately 0.5 microm). The success of the rescaling model indicates that N2 transport within the porous film is rapid enough to maintain a uniform distribution throughout the film on a time scale faster than desorption.
Yusuke Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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layer by layer motif hybridization Nanoporous nickel oxide flakes wrapped into graphene oxide sheets toward enhanced oxygen reduction reaction
Chemical Communications, 2015Co-Authors: Mohamed Zakaria, Victor Malgras, Toshiaki Takei, Yusuke YamauchiAbstract:Herein we report a novel strategy involving the hybridization of Nanoporous NiO flakes with graphene oxide (GO) sheets. The as-prepared flake-like nickel cyano-bridged coordination polymers (NiCNNi) are hybridized with GO sheets and thermally treated in air, so the organic Materials can be removed without affecting the integrity of the parent GO sheets. Thus, the layer-by-layer construction followed by a thermal treatment can produce a new hybrid Nanoporous Material consisting of NiO and GO. The obtained hybrid Material exhibits an efficient catalytic activity and stability for the oxygen reduction reaction (ORR).
Mohamed Zakaria - One of the best experts on this subject based on the ideXlab platform.
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layer by layer motif hybridization Nanoporous nickel oxide flakes wrapped into graphene oxide sheets toward enhanced oxygen reduction reaction
Chemical Communications, 2015Co-Authors: Mohamed Zakaria, Victor Malgras, Toshiaki Takei, Yusuke YamauchiAbstract:Herein we report a novel strategy involving the hybridization of Nanoporous NiO flakes with graphene oxide (GO) sheets. The as-prepared flake-like nickel cyano-bridged coordination polymers (NiCNNi) are hybridized with GO sheets and thermally treated in air, so the organic Materials can be removed without affecting the integrity of the parent GO sheets. Thus, the layer-by-layer construction followed by a thermal treatment can produce a new hybrid Nanoporous Material consisting of NiO and GO. The obtained hybrid Material exhibits an efficient catalytic activity and stability for the oxygen reduction reaction (ORR).
Tykhon Zubkov - One of the best experts on this subject based on the ideXlab platform.
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material ii diffusion limited kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R EngstromAbstract:The adsorption, desorption, and diffusion kinetics of N2 on thick (up to ∼9μm) porous films of amorphous solid water (ASW) films were studied using molecular beam techniques and temperature programmed desorption. Porous ASW films were grown on Pt(111) at low temperature ( 1μm), N2 adsorption at 27K results in a nonuniform distribution, where most of N2 is trapped in the outer region of the film. Redistribution of N2 can be induced by thermal annealing. The apparent activation energy for this process is ∼7kJ∕mol, which is approximately half of the desorption activation energy at the corresponding coverage. Preadsorption of Kr preferentially adsorbs onto the highest energy binding sites, thereby preventing N2 from trapping in the outer region of the film which facilitates N2 transport de...
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material i surface limited desorption kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R EngstromAbstract:The adsorption and desorption kinetics of N2 on porous amorphous solid water (ASW) films were studied using molecular beam techniques, temperature programed desorption (TPD), and reflection-absorption infrared spectroscopy. The ASW films were grown on Pt(111) at 23K by ballistic deposition from a collimated H2O beam at various incident angles to control the film porosity. The experimental results show that the N2 condensation coefficient is essentially unity until near saturation, independent of the ASW film thickness indicating that N2 transport within the porous films is rapid. The TPD results show that the desorption of a fixed dose of N2 shifts to higher temperature with ASW film thickness. Kinetic analysis of the TPD spectra shows that a film thickness rescaling of the coverage-dependent activation energy curve results in a single master curve. Simulation of the TPD spectra using this master curve results in a quantitative fit to the experiments over a wide range of ASW thicknesses (up to 1000 layers...
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adsorption desorption and diffusion of nitrogen in a model Nanoporous Material i surface limited desorption kinetics in amorphous solid water
Journal of Chemical Physics, 2007Co-Authors: Tykhon Zubkov, Scott R Smith, Todd R Engstrom, Bruce D KayAbstract:The adsorption and desorption kinetics of N2 on porous amorphous solid water (ASW) films were studied using molecular beam techniques, temperature programed desorption (TPD), and reflection-absorption infrared spectroscopy. The ASW films were grown on Pt(111) at 23 K by ballistic deposition from a collimated H2O beam at various incident angles to control the film porosity. The experimental results show that the N2 condensation coefficient is essentially unity until near saturation, independent of the ASW film thickness indicating that N2 transport within the porous films is rapid. The TPD results show that the desorption of a fixed dose of N2 shifts to higher temperature with ASW film thickness. Kinetic analysis of the TPD spectra shows that a film thickness rescaling of the coverage-dependent activation energy curve results in a single master curve. Simulation of the TPD spectra using this master curve results in a quantitative fit to the experiments over a wide range of ASW thicknesses (up to 1000 layers, approximately 0.5 microm). The success of the rescaling model indicates that N2 transport within the porous film is rapid enough to maintain a uniform distribution throughout the film on a time scale faster than desorption.
N A Ahmed - One of the best experts on this subject based on the ideXlab platform.
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develop a refined truncated cubic lattice structure for nonlinear large amplitude vibrations of micro nano beams made of Nanoporous Materials
Engineering With Computers, 2020Co-Authors: S Sahmani, A M Fattahi, N A AhmedAbstract:Pore size and interconnectivity have essential role in different biological applications of synthetic porous bioMaterials. Recent improvements in technology make it possible to produce Nanoporous Materials having pores of controllable dimensions at atomic scale. In the present study, based upon a refined truncated cube lattice structure, the elastic mechanical properties of Nanoporous Materials have been extracted explicitly in terms of the pore size. Afterwards, the size-dependent nonlinear large-amplitude vibrations of micro/nano-beams made of the Nanoporous Material are explored. To this purpose, the nonlocal strain gradient elasticity theory is utilized within the framework of the refined hyperbolic shear deformation beam theory to capture the both small-scale effects of hardening-stiffness and softening-stiffness. Finally, the Galerkin method together with an improved perturbation technique is employed to construct explicit analytical expression for the nonlocal strain gradient frequency-deflection response of micro/nano-beams made of Nanoporous Materials. It is demonstrated that, by increasing the pore size, the nonlinear frequency associated with the large-amplitude vibration of micro/nano-beams made of Nanoporous Material reduces, but the rate of this reduction becomes lower for higher pore size.
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Develop a refined truncated cubic lattice structure for nonlinear large-amplitude vibrations of micro/nano-beams made of Nanoporous Materials
Engineering with Computers, 2019Co-Authors: S Sahmani, A M Fattahi, N A AhmedAbstract:Pore size and interconnectivity have essential role in different biological applications of synthetic porous bioMaterials. Recent improvements in technology make it possible to produce Nanoporous Materials having pores of controllable dimensions at atomic scale. In the present study, based upon a refined truncated cube lattice structure, the elastic mechanical properties of Nanoporous Materials have been extracted explicitly in terms of the pore size. Afterwards, the size-dependent nonlinear large-amplitude vibrations of micro/nano-beams made of the Nanoporous Material are explored. To this purpose, the nonlocal strain gradient elasticity theory is utilized within the framework of the refined hyperbolic shear deformation beam theory to capture the both small-scale effects of hardening-stiffness and softening-stiffness. Finally, the Galerkin method together with an improved perturbation technique is employed to construct explicit analytical expression for the nonlocal strain gradient frequency-deflection response of micro/nano-beams made of Nanoporous Materials. It is demonstrated that, by increasing the pore size, the nonlinear frequency associated with the large-amplitude vibration of micro/nano-beams made of Nanoporous Material reduces, but the rate of this reduction becomes lower for higher pore size.
