Physics Commons^™

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

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 …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

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 …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

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 …

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 …

Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger

Other Nanotechnology Publications

The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes …

Automated Crystal Phase And Orientation Mapping Of Nanocrystals In A Transmission Electron Microscope, Peter Moeck, Sergei Rouvimov, Edgar F. Rauch, Stavros Nicolopoulos

Physics Faculty Publications and Presentations

An automated technique for the mapping of nanocrystal phases and orientations in a transmission electron microscope (TEM) is described. It is based on the projected reciprocal lattice geometry that is extracted from electron diffraction spot patterns. The required hardware allows for a scanning‐precession movement of the primary electron beam on the crystalline sample and can be interfaced to any newer or older TEM. The software that goes with this hardware is flexible in its intake of raw data so that it can also create orientation and phase maps of nanocrystal from high resolution TEM (HRTEM) images. When the nanocrystals possess …

Magnetic Sensors For Biodetection, Pranjali Vineet Sneha Deshpande

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of thesis is to design magnetic sensor for detection of nanoparticles. Recently integrating the standard laboratory techniques into integrated system on chip is growing attention. Recent development is to combine magnetic markers and magnetoresistive sensors together in magnetic chip. In this thesis two magnetoresistive sensors were studied and designed.

By applying magnetic fields, magnetic nanoparticles can be manipulated on-chip, which can be utilized to pull the molecules to specific binding sites or to test the binding strength and distinguish between specifically and non-specifically bound molecules

Magnetoresistive sensors are compatible with the semiconductor industry which provides electronic signal directly …

Nanometrology Device Standards For Scanning Probe Mmicroscopes And Processes For Their Fabrication And Use, Peter Moeck

Physics Faculty Publications and Presentations

Nanometrology device standards and methods for fabricating and using such devices in conjunction With scanning probe microscopes are described. The fabrication methods comprise: (1) epitaxial growth that produces nanometer sized islands of knoWn morphology, structural, morphological and chemical stability in typical nanometrology environments, and large height-to-width nano-island aspect ratios, and (2) marking suitable crystallographic directions on the device for alignment With a scanning direction.

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Agegnehu Atena, Mikhail Khenner

Mathematics Faculty Publications

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 …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Agegnehu Atena, Mikhail Khenner

Mathematics Faculty Publications

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 …

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

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

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 …

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 …

Dc Electrokinetic Transport Of Cylindrical Cells In Straight Microchannels, Ye Ai, Ali Beskok, David T. Gauthier, Sang W. Joo, Shizhi Qian

Biological Sciences Faculty Publications

Electrokinetic transport of cylindrical cells under dc electric fields in a straight microfluidic channel is experimentally and numerically investigated with emphasis on the dielectrophoretic (DEP) effect on their orientation variations. A two-dimensional multiphysics model, composed of the Navier-Stokes equations for the fluid flow and the Laplace equation for the electric potential defined in an arbitrary Lagrangian-Eulerian framework, is employed to capture the transient electrokinetic motion of cylindrical cells. The numerical predictions of the particle transport are in quantitative agreement with the obtained experimental results, suggesting that the DEP effect should be taken into account to study the electrokinetic transport of …

Research On The Transport And Deposition Of Nanoparticles In A Rotating Curved Pipe, Jianzhong Lin, Peifeng Lin, Huajun Chen

Mechanical Engineering Faculty Research

A finite-volume code and the SIMPLE scheme are used to study the transport and deposition of nanoparticles in a rotating curved pipe for different angular velocities, Dean numbers, and Schmidt numbers. The results show that when the Schmidt number is small, the nanoparticle distributions are mostly determined by the axial velocity. When the Schmidt number is many orders of magnitude larger than 1, the secondary flow will dominate the nanoparticle distribution. When the pipe corotates, the distribution of nanoparticle mass fraction is similar to that for the stationary case. There is a “hot spot” deposition region near the outside edge …

Precession Electron Diffraction And Its Advantages For Structural Fingerprinting In The Transmission Electron Microscope, Peter Moeck, Sergei Rouvimov

Physics Faculty Publications and Presentations

The foundations of precession electron diffraction in a transmission electron microscope are outlined. A brief illustration of the fact that laboratory-based powder X-ray diffraction fingerprinting is not feasible for nanocrystals is given. A procedure for structural fingerprinting of nanocrystals on the basis of structural data that can be extracted from precession electron diffraction spot patterns is proposed.

Electron Microscopy And Optical Characterization Of Cadmium Sulphide Nanocrystals Deposited On The Patterned Surface Of Diatom Biosilica, Timothy Gutu, Debra K. Gale, Clayton Jeffryes, Wei Wang, Chih-Hung Chang, Gregory L. Rorrer, Jun Jiao

Physics Faculty Publications and Presentations

Intricately patterned biosilica obtained from the shell of unicellular algae called diatoms serve as novel templates for fabrication of optoelectronic nanostructures. In this study, the surface of diatom frustules that possessed hierarchical architecture ordered at the micro and nanoscale was coated with a nanostructured polycrystalline cadmium sulphide (CdS) thin film using a chemical bath deposition technique. The CdS thin film was composed of spherical nanoparticles with a diameter of about 75 nm. The CdS nanoparticle thin film imparted new photoluminescent properties to the intricately patterned diatom nanostructure. The imparted photoluminescent properties were dependent on the CdS coverage onto the frustules …

Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Xiangchun Xuan, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

Pressure-driven transport of particles through a symmetric converging-diverging microchannel is studied by solving a coupled nonlinear system, which is composed of the Navier-Stokes and continuity equations using the arbitrary Lagrangian-Eulerian finite-element technique. The predicted particle translation is in good agreement with existing experimental observations. The effects of pressure gradient, particle size, channel geometry, and a particle's initial location on the particle transport are investigated. The pressure gradient has no effect on the ratio of the translational velocity of particles through a converging-diverging channel to that in the upstream straight channel. Particles are generally accelerated in the converging region and then …