The Experts below are selected from a list of 307539 Experts worldwide ranked by ideXlab platform
Michael S Strano - One of the best experts on this subject based on the ideXlab platform.
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multimodal biomedical imaging with asymmetric single walled carbon nanotube iron oxide nanoparticle complexes
Nano Letters, 2007Co-Authors: Jong Hyun Choi, Freddy T Nguyen, Paul W Barone, Daniel A Heller, Anthonie E Moll, Dhaval Patel, Stephen A Boppart, Michael S StranoAbstract:Magnetic iron oxide nanoparticles and near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWNT) form heterostructured complexes that can be utilized as multimodal bioimaging agents. Fe catalyst-grown SWNT were individually dispersed in aqueous solution via encapsulation by oligonucleotides with the sequence d(GT)15, and enriched using a 0.5 T magnetic array. The resulting nanotube complexes show distinct NIR fluorescence, Raman scattering, and visible/NIR absorbance features, corresponding to the various nanotube species. AFM and cryo-TEM images show DNA-encapsulated complexes composed of a ∼3 nm particle attached to a carbon nanotube on one end. X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) measurements reveal that the nanoparticles are primarily Fe2O3 and superparamagnetic. The Fe2O3 particle-enriched nanotube solution has a magnetic particle content of ∼35 wt %, a magnetization satuRation of ∼56 emu/g, and a magnetic relaxation time Scale Ratio (T1/T2) of a...
Hiroshi Kawamura - One of the best experts on this subject based on the ideXlab platform.
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DNS of turbulent heat transfer in a channel flow with a varying streamwise thermal boundary condition
Heat Transfer—Asian Research, 2006Co-Authors: Yohji Seki, Hiroshi KawamuraAbstract:Direct numerical simulation (DNS) was performed for the turbulent heat transfer in a channel flow. In the present study, the effect of the thermal boundary condition was examined. DNS was carried out for varying streamwise thermal boundary conditions (Reτ = 180) with Pr = 0.71 to obtain statistical mean temperatures, temperature variances, budget terms, and time Scale Ratios. The results obtained indicate that the time Scale Ratio varies along the stream direction. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 265–278, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20114
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DNS of Turbulent Heat Transfer in a Channel Flow with Streamwisely Varying Thermal Boundary Condition
Transactions of the Japan Society of Mechanical Engineers Series B, 2005Co-Authors: Yohji Seki, Hiroshi KawamuraAbstract:Direct numerical simulation (DNS) have been performed for the turbulent heat transfer in a channel flow. In the present study, effect of thermal boundary condition is examined. DNS has been carried out for streamwisely thermal boundary conditions (Reτ=180) with Pγ=0.71 to obtain statistical mean temperatures, temperature variances, budget terms and time Scale Ratios etc. The obtained results have indicated that the time Scale Ratio varies along a streamwise.
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dns of turbulent heat transfer in channel flow with respect to reynolds and prandtl number effects
International Journal of Heat and Fluid Flow, 1999Co-Authors: Hiroshi Kawamura, Hiroyuki Abe, Yuichi MatsuoAbstract:Abstract The direct numerical simulation (DNS) of turbulent heat transfer in a channel flow has been carried out to investigate the Reynolds and Prandtl number effects on the turbulent heat transport. The configuRation is a fully developed turbulent channel flow with uniform heating from both walls. The Reynolds numbers based on the friction velocity and the channel half width are 180 and 395, and the molecular Prandtl numbers are 0.025, 0.2 and 0.71. The statistical quantities such as the temperature variance, turbulent heat fluxes, turbulent Prandtl number and the time Scale Ratio are obtained and the effects of the Reynolds and Prandtl numbers are examined. Budget terms of the temperature variance and the turbulent heat fluxes are also calculated. In addition, the instantaneous flow and thermal fields are visualized in order to investigate the structures of streaks and vortices.
Oleg V Prezhdo - One of the best experts on this subject based on the ideXlab platform.
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effect of aspect Ratio on multiparticle auger recombination in single walled carbon nanotubes time domain atomistic simulation
Nano Letters, 2018Co-Authors: David Casanova, Oleg V PrezhdoAbstract:Many-particle Auger-type processes are common in nanoScale materials due to a combination of high densities of states that can support multiple excitations and substantial Coulomb coupling between charges enhanced by quantum confinement. Auger decay dynamics in (10,5) semiconductor carbon nanotubes (CNT) with different aspect Ratios and particle densities are simulated in time domain using global flux surface hopping, recently developed and implemented within Kohn–Sham tight-binding density functional theory. Despite an increasing density of states, the multiparticle Auger recombination rate decreases in longer CNTs. The atomistic simulation shows that the effect is directly related to the coupling between electronic states, which decreases as the aspect Ratio becomes larger. The dependence on tube length is stronger for three-exciton than two-exciton recombination and the calculated time Scale Ratio approaches the experimental value measured for long CNTs. Phonon-assisted transitions play a particularly ...
Jong Hyun Choi - One of the best experts on this subject based on the ideXlab platform.
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multimodal biomedical imaging with asymmetric single walled carbon nanotube iron oxide nanoparticle complexes
Nano Letters, 2007Co-Authors: Jong Hyun Choi, Freddy T Nguyen, Paul W Barone, Daniel A Heller, Anthonie E Moll, Dhaval Patel, Stephen A Boppart, Michael S StranoAbstract:Magnetic iron oxide nanoparticles and near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWNT) form heterostructured complexes that can be utilized as multimodal bioimaging agents. Fe catalyst-grown SWNT were individually dispersed in aqueous solution via encapsulation by oligonucleotides with the sequence d(GT)15, and enriched using a 0.5 T magnetic array. The resulting nanotube complexes show distinct NIR fluorescence, Raman scattering, and visible/NIR absorbance features, corresponding to the various nanotube species. AFM and cryo-TEM images show DNA-encapsulated complexes composed of a ∼3 nm particle attached to a carbon nanotube on one end. X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) measurements reveal that the nanoparticles are primarily Fe2O3 and superparamagnetic. The Fe2O3 particle-enriched nanotube solution has a magnetic particle content of ∼35 wt %, a magnetization satuRation of ∼56 emu/g, and a magnetic relaxation time Scale Ratio (T1/T2) of a...
Pavel Ditl - One of the best experts on this subject based on the ideXlab platform.
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Local turbulent energy dissipation rate in an agitated vessel: New approach to dimensionless definition
Theoretical Foundations of Chemical Engineering, 2017Co-Authors: Radek Šulc, Pavel DitlAbstract:Using theory of turbulence, particularly using turbulence spectrum analysis, the relations e* = e/(u 4/ν) = const., vK/u = const. and Λ/ηK = const. were derived. Assuming that u ∝ (Nd) from this it follows that the widely used dimensionless local turbulent energy dissipation rate defined as e/((N 3 d 2) is directly proportional to impeller Reynolds number, i.e. e/((N 3 d 2) ∝ Re, and length Scale Ratio Λ/d is indirectly proportional to impeller Reynolds number, i.e. Λ/d ∝ Re–1, in an agitated vessel at high Reynolds number. The relations obtained by turbulence spectrum analysis were used for estimation of local turbulent energy dissipation rates experimentally measured by Stahl Wernersson and Tragardh (1998, 1999) covering the range of Re = 87600–910200 and own experimental data covering the range of Re = 50000–189000. The experiments have been performed in tanks of 300 mm and 400 mm in the inner diameter for three different viscosities and for various impeller rotational speeds.
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Local turbulent energy dissipation rate in an agitated vessel: New approach to dimensionless definition
Theoretical Foundations of Chemical Engineering, 2017Co-Authors: Radek Šulc, Pavel DitlAbstract:Using theory of turbulence, particularly using turbulence spectrum analysis, the relations ε^* = ε/( u ^4/ν) = const., v_K/ u = const. and Λ/η_K = const. were derived. Assuming that u ∝ ( Nd ) from this it follows that the widely used dimensionless local turbulent energy dissipation rate defined as ε/(( N ^3 d ^2) is directly proportional to impeller Reynolds number, i.e. ε/(( N ^3 d ^2) ∝ Re, and length Scale Ratio Λ/ d is indirectly proportional to impeller Reynolds number, i.e. Λ/ d ∝ Re^–1, in an agitated vessel at high Reynolds number. The relations obtained by turbulence spectrum analysis were used for estimation of local turbulent energy dissipation rates experimentally measured by Ståhl Wernersson and Trägårdh (1998, 1999) covering the range of Re = 87600–910200 and own experimental data covering the range of Re = 50000–189000. The experiments have been performed in tanks of 300 mm and 400 mm in the inner diameter for three different viscosities and for various impeller rotational speeds.
