The Experts below are selected from a list of 25878 Experts worldwide ranked by ideXlab platform

Charles Hosten - One of the best experts on this subject based on the ideXlab platform.

  • The Role of Propagating and Localized Surface Plasmons for SERS Enhancement in Periodic Nanostructures
    Plasmonics, 2012
    Co-Authors: Francisco J. Bezares, Joshua D. Caldwell, Orest Glembocki, Ronald W. Rendell, Mariya Feygelson, Maraizu Ukaegbu, Richard Kasica, Loretta Shirey, Nabil D. Bassim, Charles Hosten
    Abstract:

    Periodic arrays of plasmonic nanopillars have been shown to provide large, uniform surface-enhanced Raman scattering (SERS) enhancements. We show that these enhancements are the result of the combined impact of localized and propagating surface plasmon modes within the plasmonic architecture. Here, arrays of periodically arranged silicon nanopillars of varying sizes and interpillar gaps were fabricated to enable the exploration of the SERS response from two different structures; one featuring only localized surface plasmon (LSP) modes and the other featuring LSP and propagating (PSP) modes. It is shown that the LSP modes determine the optimal architecture, and thereby determine the Optimum Diameter for the structures at a given incident. However, the increase in the SERS enhancement factor for a system in which LSP and PSP cooperatively interact was measured to be over an order of magnitude higher and the peak in the Diameter dependence was significantly broadened, thus, such structures not only provide larger enhancement factors but are also more forgiving of lithographic variations.

Michael R Muller - One of the best experts on this subject based on the ideXlab platform.

  • an experimental investigation of the Optimum geometry for the cold end orifice of a vortex tube
    Applied Thermal Engineering, 2009
    Co-Authors: Sachin U Nimbalkar, Michael R Muller
    Abstract:

    Abstract A vortex tube is a simple mechanical device, which splits a compressed gas stream into a cold and hot stream without any chemical reactions or external energy supply. This paper presents the results of a series of experiments focusing on various geometries of the “cold end side” for different inlet pressures and cold fractions. Specifically, the tests were conducted using different cold end orifice Diameters. Energy separation and energy flux separation efficiencies are defined and used to recover characteristic properties of the vortex tube. These are used to show an appropriate scale to non-dimensionalize the energy separation effect. The experimental results indicate that there is an Optimum Diameter of cold end orifice for achieving maximum energy separation. The results also show that the maximum value of energy separation was always reachable at a 60% cold fraction irrespective of the orifice Diameter and the inlet pressure. The results are compared with the previous studies on internal flow structure, and optimal operating parameters are shown to be consistent with a matching of orifice size with the secondary circulation being observed.

Francisco J. Bezares - One of the best experts on this subject based on the ideXlab platform.

  • The Role of Propagating and Localized Surface Plasmons for SERS Enhancement in Periodic Nanostructures
    Plasmonics, 2012
    Co-Authors: Francisco J. Bezares, Joshua D. Caldwell, Orest Glembocki, Ronald W. Rendell, Mariya Feygelson, Maraizu Ukaegbu, Richard Kasica, Loretta Shirey, Nabil D. Bassim, Charles Hosten
    Abstract:

    Periodic arrays of plasmonic nanopillars have been shown to provide large, uniform surface-enhanced Raman scattering (SERS) enhancements. We show that these enhancements are the result of the combined impact of localized and propagating surface plasmon modes within the plasmonic architecture. Here, arrays of periodically arranged silicon nanopillars of varying sizes and interpillar gaps were fabricated to enable the exploration of the SERS response from two different structures; one featuring only localized surface plasmon (LSP) modes and the other featuring LSP and propagating (PSP) modes. It is shown that the LSP modes determine the optimal architecture, and thereby determine the Optimum Diameter for the structures at a given incident. However, the increase in the SERS enhancement factor for a system in which LSP and PSP cooperatively interact was measured to be over an order of magnitude higher and the peak in the Diameter dependence was significantly broadened, thus, such structures not only provide larger enhancement factors but are also more forgiving of lithographic variations.

Yuichi Mitsutake - One of the best experts on this subject based on the ideXlab platform.

  • CHF characteristics and correlations of concentric-tube open thermosyphon working with R22
    International Journal of Heat and Mass Transfer, 2005
    Co-Authors: M. Ashraful Islam, Masanori Monde, Yuichi Mitsutake
    Abstract:

    Abstract Experiments are performed to understand the critical heat flux (CHF) mechanism in a concentric-tube open thermosyphon working with R22. An electrically heated bottom-closed outer tube with an unheated inner tube inserted concentrically serves as an evaporator of the thermosyphon. CHF data are collected by using saturated R22 at 1.5, 2.0 and 2.5 MPa by varying different geometrical parameters of the thermosyphon. For a particular outer tube, there is an Optimum Diameter of the inner tube for which the CHF is maximum. The Optimum Diameter of the inner tube is about half of the Diameter of the outer tube and divides the CHF into two characteristic regions. Available correlations for predicting the CHF in each region are compared with the present data and more generalized correlations have been proposed.

  • Experimental study of critical heat flux in concentric-tube open thermosyphon
    International Journal of Heat and Mass Transfer, 1998
    Co-Authors: Ashraful Islam, Masanori Monde, Mohammad Z. Hasan, Yuichi Mitsutake
    Abstract:

    Abstract An experimental study has been performed to understand the critical heat flux (CHF) mechanism in an open concentric-tube thermosyphon by which the CHF can be increased by several times compared to a conventional one. Experiments are conducted with saturated water, R113, and ethanol at various working pressures and by varying different geometrical parameters of the thermosyphon such as inner Diameter of the outer tube, outer Diameter of the inner tube, and heated length. For a particular heated tube Diameter working with a specific fluid, there is an Optimum Diameter of the inner tube for which the CHF is maximum. The Optimum Diameter of the inner tube divides the CHF into two characteristic regions. The CHF characteristics in each region are discussed and then correlations for predicting the CHF data are proposed.

Hong Liang - One of the best experts on this subject based on the ideXlab platform.

  • Hierarchical structured nickel–copper hybrids via simple electrodeposition
    Journal of Applied Electrochemistry, 2018
    Co-Authors: Yuan Yue, Keeley Coburn, Brady Reed, Hong Liang
    Abstract:

    A novel hierarchical structure is reported that comprises micro-channeled nickel deposited onto a copper substrate. The fabrication process is a one-step galvanostatic electrodeposition in a system containing a Cu cathode, graphite anode, and Ni2+/NH4+ electrolyte. Results were obtained by the characterization of vertically aligned micro-channels in Ni. The pore density, depth, and Diameter are controlled by varying electrodeposition conditions. The addition of ammonium ions, increased current, and longer deposition time are found to promote formation of high density pores with small Diameters leading to those micro-channels. The channel’s Optimum Diameter ranged from 8 to 10 µm with depths of 20–25 µm. Adding ammonium ions also generated streams of hydrogen bubbles that formed on the cathode surface. Those bubbles hinder the nucleation of Ni, resulting in the selective nucleation and therefore the growth of micro-channels. The novel hierarchical Ni/Cu hybrids have the potential to be used for current collectors for battery electrodes, substrates to grow nanostructured oxides, and among others.Graphical Abstract