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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner
Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner
Mikhail Khenner
A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam …
Effect Of Salts On The Electrospinning Of Poly(Vinyl Alcohol), Jonathan J. Stanger, Nick Tucker, Mark P. Staiger, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Nigel Larsen
Effect Of Salts On The Electrospinning Of Poly(Vinyl Alcohol), Jonathan J. Stanger, Nick Tucker, Mark P. Staiger, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Nigel Larsen
Jonathan J Stanger
Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept …
Effect Of Charge Density On The Taylor Cone In Electrospinning, Jonathan J. Stanger, Nick Tucker, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Mark P. Staiger
Effect Of Charge Density On The Taylor Cone In Electrospinning, Jonathan J. Stanger, Nick Tucker, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Mark P. Staiger
Jonathan J Stanger
A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip …
The Effect Of Electrode Configuration And Substrate Material On The Mass Deposition Rate Of Electrospinning, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Nigel Larsen, Mark P. Staiger, Roger Reeves
The Effect Of Electrode Configuration And Substrate Material On The Mass Deposition Rate Of Electrospinning, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Nigel Larsen, Mark P. Staiger, Roger Reeves
Jonathan J Stanger
Poly(vinyl alcohol) (PVOH) was electrospun using different methods to charge the polymer solution. A positive high voltage relative to the collecting electrode significantly increased the fibre deposition rate. Electron microscopy showed that approximately half of the increase in fibre mass was due to thicker fibres being deposited. The current flowing from the grounded electrode was measured to determine the charge carried on the PVOH jet. This showed that for a positive voltage charging condition there is a much larger current and hence more charge carriers generated in the PVOH solution. As a result, more mass is ejected from the Taylor …
Preparation Of Wo3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template, Nilofar Asim, S. Radiman, M.A. Bin Yarmo
Preparation Of Wo3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template, Nilofar Asim, S. Radiman, M.A. Bin Yarmo
Nilofar Asim
WO3 is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of WO3 nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of WO3 nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammonium bromide) as the organic supermolecular template and WCl6 and NH4 OH as the inorganic precursor and counter ion source, respectively. The effects of reaction temperature and surfactant concentration in …
Rhodium Nanoparticle Shape Dependence In The Reduction Of No By Co, James Russell Renzas, Yawen Zhang, Wenyu Huang, Gabor Somoraji
Rhodium Nanoparticle Shape Dependence In The Reduction Of No By Co, James Russell Renzas, Yawen Zhang, Wenyu Huang, Gabor Somoraji
Wenyu Huang
The shape dependence of the catalytic reduction of nitric oxide by carbon monoxide on rhodium nanopoly- hedra and nanocubes was studied from 230 to 270 ° C. The nanocubes are found to exhibit higher turnover frequency and lower activation energy than the nanopolyhedra. These trends are compared to previous studies on Rh single crystals.
Sub-10 Nm Platinum Nanocrystals With Size And Shape Control: Catalytic Study For Ethylene And Pyrrole Hydrogenation, Chia-Kuang Tsung, John N. Kuhn, Wenyu Huang, Cesar Aliaga, Ling-I Hung, Gabor A. Somorjai, Peidong Yang
Sub-10 Nm Platinum Nanocrystals With Size And Shape Control: Catalytic Study For Ethylene And Pyrrole Hydrogenation, Chia-Kuang Tsung, John N. Kuhn, Wenyu Huang, Cesar Aliaga, Ling-I Hung, Gabor A. Somorjai, Peidong Yang
Wenyu Huang
Platinum nanocubes and nanopolyhedra with tunable size from 5 to 9 nm were synthesized by controlling the reducing rate of metal precursor ions in a one-pot polyol synthesis. A two-stage process is proposed for the simultaneous control of size and shape. In the first stage, the oxidation state of the metal ion precursors determined the nucleation rate and consequently the number of nuclei. The reaction temperature controlled the shape in the second stage by regulation of the growth kinetics. These well-defined nanocrystals were loaded into MCF-17 mesoporous silica for examination of catalytic properties. Pt loadings and dispersions of the supported …
Self-Organized Ultrathin Oxide Nanocrystals, Ziyang Huo, Chia-Kuang Tsung, Wenyu Huang, Melissa Fardy, Ruoxue Yan, Xiaofeng Zhang, Yandong Li, Peidong Yang
Self-Organized Ultrathin Oxide Nanocrystals, Ziyang Huo, Chia-Kuang Tsung, Wenyu Huang, Melissa Fardy, Ruoxue Yan, Xiaofeng Zhang, Yandong Li, Peidong Yang
Wenyu Huang
Sub-2-nm (down to one-unit cell) uniform oxide nanocrystals and highly ordered superstructures were obtained in one step using oleylamine and oleic acid as capping and structure directing agents. The cooperative nature of the nanocrystal growth and assembly resulted in mesoscopic one-dimensional ribbon-like superstructures made of these ultrathin nanocrystals. The process reported here is general and can be readily extended to the production of many other transition metal (TiO2, ZnO, Nb2O5) and rare earth oxide (Eu2O3, Sm2O3, Er2O3, Y2O3, Tb2O3, and Yb2O3) systems.
Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Agegnehu Atena, Mikhail Khenner
Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Agegnehu Atena, Mikhail Khenner
Mikhail Khenner
In this paper the lubrication-type dynamical model is developed of a molten, pulsed laser-irradiated metallic film. The heat transfer problem that incorporates the absorbed heat from a single beam or interfering beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the peak laser beam intensity, the film optical thickness, the Biot and …