Nanoscience and Nanotechnology Commons^™

Effects Of Aggregate Structure On Hot-Mix Asphalt Rutting Performance In Low Traffic Volume Local Pavements, Yong-Rak Kim, Hee Mun Park, Francisco Thiago Sacramento Aragão, Jamilla Emi Sudo Lutif

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this study is to evaluate the effect of mix gradations associated with the Superpave restricted zone on rutting potential specifically for low traffic volume roadways. Although the elim-ination of the restricted zone requirement in Superpave mix design is highly recommended, some questions still remain unanswered as the research conclusions supporting the elimination of the re-stricted zone were largely made for medium to high traffic volume roadways, where aggregates are highly crushed and of good quality. The applicability of such research conclusions based on high traffic volume mixes needs to be verified for low volume mixes because many …

A Study Of Cantilever-Free Instrumentation For Nanoscale Magnetic Measurements, Bruce Adair Altemus

Legacy Theses & Dissertations (2009 - 2024)

The evolution of the Atomic Force Microscope (AFM) into the Magnetic Force Microscope (MFM) and Magnetic Resonance Force Microscope (MRFM) has had a substantial impact on the characterization of nanoscale phenomena. Detection of 10-17 Newtons per root Hertz has occurred with use of an ultra-sensitive cantilever along with optical interferometry methods within these geometries. The sensitivity of these platforms is dependent on the characteristics of the cantilever, where increased length and a low Young's modulus increase the force sensitivity (meters/Newtons). Using IC fabrication techniques, the realization of generating cantilevers with this sensitivity is feasible, but stress compensation layers are required …

A Study Of Cantilever-Free Instrumentation For Nanoscale Magnetic Measurements, Bruce Adair Altemus

Legacy Theses & Dissertations (2009 - 2024)

The evolution of the Atomic Force Microscope (AFM) into the Magnetic Force Microscope (MFM) and Magnetic Resonance Force Microscope (MRFM) has had a substantial impact on the characterization of nanoscale phenomena. Detection of 10-17 Newtons per root Hertz has occurred with use of an ultra-sensitive cantilever along with optical interferometry methods within these geometries. The sensitivity of these platforms is dependent on the characteristics of the cantilever, where increased length and a low Young's modulus increase the force sensitivity (meters/Newtons). Using IC fabrication techniques, the realization of generating cantilevers with this sensitivity is feasible, but stress compensation layers are required …

Continuous Glucose Monitoring Microsensor With A Nanoscale Conducting Matrix And Redox Mediator, Daniel Pesantez

Legacy Theses & Dissertations (2009 - 2024)

The major limiting factor in kidney clinical transplantation is the shortage of transplantable organs. The current inability to distinguish viability from non-viability on a prospective basis represents a major obstacle in any attempt to expand organ donor criteria. Consequently, a way to measure and monitor a relevant analyte to assess kidney viability is needed. For the first time, the initial development and characterization of a metabolic microsensor to assess kidney viability is presented. The rate of glucose consumption appears to serve as an indicator of kidney metabolism that may distinguish reversible from irreversible kidney damage. The proposed MetaSense (Metabolic Sensor) …

Nanocomposite Thin Films Of Au Nanoparticles Embedded In Yttria-Stabilized Zirconia For Plasmonic-Based Harsh Environment Gas Detection, Phillip Henry Rogers

Legacy Theses & Dissertations (2009 - 2024)

Increased health concerns due to the emission of gases linked to the production of tropospheric ozone by petroleum based fuel burning engines has resulted in the codification of more stringent emissions regulations domestically. Emissions regulations on commercial jetliners are one of the areas to be met with stricter standards. Currently there is not a sensing technology that can detect the emissions gases in the exhaust stream of a jet turbine engine with lower detection limits that meet these standards.

Progress Towards Critical Dimension Low Vacuum Scanning Electron Microscopy, Vasiliki Tileli

Legacy Theses & Dissertations (2009 - 2024)

Low vacuum scanning electron microscopy (LVSEM) is proposed and evaluated for next generation Critical Dimension (CD) metrology. Its ability to control charging artifacts and hydrocarbon contamination in order to obtain high signal-to-noise ratio, high resolution image data from insulating materials make the technology an excellent match for the increased use of high-k dielectrics and shrinking feature size in the semiconductor industry. The presence of a gas in the LVSEM chamber means that the probe characteristics and secondary electron amplification, detection, and signal-to-noise ratio differ significantly from conventional high vacuum tools. In order for low vacuum CD approaches to be viable, …

Monoclinic Optical Constants, Birefringence, And Dichroism Of Slanted Titanium Nanocolumns Determined By Generalized Ellipsometry, Daniel Schmidt, Benjamin Booso, Tino Hofmann, Eva Schubert, Andrew Sarangan, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

Generalized spectroscopic ellipsometry determines the principal monoclinic optical constants of thin films consisting of slanted titanium nanocolumns deposited by glancing angle deposition under 85° incidence and tilted from the surface normal by 47°. Form birefringence measured for wavelengths from 500 to 1000 nm renders the Ti nanocolumns monoclinic absorbing crystals with c-axis along the nanocolumns, b-axis parallel to the film interface, and 67.5° monoclinic angle between the a- and c-axes. The columnar thin film reveals anomalous optical dispersion, extreme birefringence, strong dichroism, and differs completely from bulk titanium. Characteristic bulk interband transitions are absent in the spectral range investigated.

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 …

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 …

Substituent Effect On The Electronic And Assembling Properties Of Asymmetric Phenazine Derivatives, Bin Cao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Currently, one-dimensional (1-D) nanostructures have drawn much interest because of their potential applications for nanoscale optoelectronic devices. Self-assembly (SA) based on π-conjugated systems through various intermolecular interactions has been widely used to produce 1-D nanostructure. Morphology of the assembled structures can be modified by incorporating substituents, which provide additional secondary interactions. Meanwhile, those substituents also influence the electronic properties of the molecules. Previous studies have made little effort to systematically study subsistent effects on both electronic and SA properties.

The primary objective of this research is to generate controllable 1-D structures through SA, and to provide a fundamental understanding of …

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …

One-Pot Synthesis Of Anionic (Nitrogen) And Cationic (Sulfur) Codoped High-Temperature Stable, Visible Light Active, Anatase Photocatalysts, Suresh Pillai, Declan Mccormack, Steven Hinder, Pradeepan Periyat

Articles

No abstract provided.

Synthesis Of Maleic Anhydride Grafted Polypropylene-Butadiene Copolymer And Its Application In Pp/Ommt/Sbs Composite As Compatibilizer, Qiaohuan Cheng, Zhanxia Lu, Hugh Byrne

Articles

Maleic Anhydride (MA) grafted propylene-butadiene copolymer (PPB) was prepared. FTIR and 1H-NMR results indicated that the MA molecules reacted with the double bond in the butadiene unit of the PPB and the grafting percentage increased with the butadiene content in the initial copolymer. GPC results showed the introduction of butadiene in the copolymer prevented the degradation of the PPB. The MA-g-PPB (MPPB) was applied in PP/SBS/OMMT composite as compatibilizer. In the presence of 10phr MPPB, the impact strength of the composite was improved by ~20%. XRD patterns indicated the formation of β-phase crystallization of polypropylene in the presence of MPPB …

Comparison Of Fuzzy Clustering Methods And Their Applications To Geophysics Data, David J. Miller, Carl A. Nelson, Molly Boeka Cannon, Kenneth P. Cannon

Department of Mechanical and Materials Engineering: Faculty Publications

Fuzzy clustering algorithms are helpful when there exists a dataset with subgroupings of points having indistinct boundaries and overlap between the clusters. Traditional methods have been extensively studied and used on real-world data, but require users to have some knowledge of the outcome a priori in order to determine howmany clusters to look for. Additionally, iterative algorithms choose the optimal number of clusters based on one of several performance measures. In this study, the authors compare the performance of three algorithms (fuzzy c-means, Gustafson-Kessel, and an iterative version of Gustafson-Kessel) when clustering a traditional data set as well as real-world …

Optical, Structural, And Magnetic Properties Of Cobalt Nanostructure Thin Films, D. Schmidt, A. C. Kjerstad, Tino Hofmann, Ralph Skomski, Eva Schubert, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

We report on optical, structural, and magnetic properties of two substantially different cobalt nanostructure thin films deposited at an oblique angle of incidence of 85° away from the substrate normal. Comparison is made between an achiral columnar thin film grown without substrate rotation and a chiral nanocoil sculptured thin film by glancing angle deposition with substrate rotation. Generalized spectroscopic ellipsometry is employed to determine geometrical structure properties and the anisotropic optical constants of the films in the spectral range from 400 to 1000 nm. The magnetic properties are analyzed with a superconducting quantum interference device magnetometer. Both nanostructure thin films …

Experimental Investigation Of A Novel Blast Wave Mitigation Device, Zhenbi Su, Wen Peng, Zhaoyan Zhang, George Gogos, Reed Skaggs, Bryan Cheeseman, Chian Fong Yen

Department of Mechanical and Materials Engineering: Faculty Publications

A novel blast wave mitigation device was investigated experimentally in this paper. The device consists of a pistoncylinder assembly. A shock wave is induced within the cylinder when a blast wave impacts on the piston. The shock wave propagates inside the device and is reflected repeatedly. The shock wave propagation process inside the device lengthens the duration of the force on the base of the device to several orders of magnitude of the duration of the blast wave, while it decreases the maximum pressure over an order of magnitude. Two types of experiments were carried out to study the blast …

Metal Induced Crystallization Of Silicon Thin Films, Sandeep Kumar Raju Sangaraju

UNLV Theses, Dissertations, Professional Papers, and Capstones

Low temperature crystallization of thin film silicon is important for many industrial applications including flat panel displays and silicon thin film solar cells. Unfortunately this remains a major challenge since crystallization temperature of silicon is above 1,000 degrees Celsius, thus limiting to substrates that can tolerate high temperatures. The inability to deposit crystalline thin films on glass substrates is the reason why flat panel display industry uses amorphous silicon for LCD active matrix displays. Thus the ability to deposit crystallized thin film silicon at low temperatures will have significant impact on thin film silicon applications. It has been observed that …

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 …

The Bundle Dispersion Of Swnt On Interaction With P-Terphenyl, Theresa Hedderman, Anika Mostaert, Anne Shanahan, Hugh Byrne

Articles

This paper investigates the interaction and bundle dispersion of single walled carbon nanotubes (SWNT) produced by arc discharge and by the high pressure decomposition of carbon monoxide, often referred to as the HiPco method, in the presence of the molecule p-terphenyl. The study will show that the extent of SWNT bundle dispersion and the degree of interaction with p-terphenyl is related to the level of purity of the SWNT sample. This study compares the bundle dispersion and interaction of SWNT with p-terphenyl in their as produced state and after purification. A number of spectroscopic and microscopic techniques are used to …

Titanium Dioxide Nanoparticles Induce Oxidative Stress And Dna-Adduct Formation But Not Dna-Breakage In Human Lung Cells, Kunal Bhattacharya, Maria Davoren, Jens Boertz, Roel P.F. Schins, Eik Hoffmann, Elke Dopp

Articles

Titanium dioxide (TiO2), also known as titanium (IV) oxide or anatase, is the naturally occurring oxide of titanium. It is also one of the most commercially used form. To date, no parameter has been set for the average ambient air concentration of TiO2 nanoparticles (NP) by any regulatory agency. Previously conducted studies had established these nanoparticles to be mainly non-cyto- and -genotoxic, although they had been found to generate free radicals both acellularly (specially through photocatalytic activity) and intracellularly. The present study determines the role of TiO2-NP (anatase, ∅ < 100 nm) using several parameters such as cyto- and genotoxicity, DNA-adduct formation and generation of free radicals following its uptake by human lung cells in vitro. For comparison, iron containing nanoparticles (hematite, Fe2O3, ∅ < 100 nm) were used. The results of this study showed that both types of NP were located in the cytosol near the nucleus. No particles were found inside the nucleus, in mitochondria or ribosomes. Human lung fibroblasts (IMR-90) were more sensitive regarding cyto- and genotoxic effects caused by the NP than human bronchial epithelial cells (BEAS-2B). In contrast to hematite NP, TiO2-NP did not induce DNA-breakage measured by the Comet-assay in both cell types. Generation of reactive oxygen species (ROS) was measured acellularly (without any photocatalytic activity) as well as intracellularly for both types of particles, however, the iron-containing NP needed special reducing conditions before pronounced radical generation. A high level of DNA adduct formation (8-OHdG) was observed in IMR-90 cells exposed to TiO2-NP, but not in cells exposed to hematite NP. Our study demonstrates different modes of action for TiO2- and Fe2O3-NP. Whereas TiO2-NP were able to generate elevated amounts of free radicals, which induced indirect genotoxicity mainly by DNA-adduct formation, Fe2O3-NP were clastogenic (induction of DNA-breakage) and required reducing conditions for radical formation.

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 …

Preparation, Characterization Of Nipam And Nipam/Bam Copolymer Nanoparticles And Their Acute Toxicity Testing Using An Aquatic Test Battery, Pratap Naha, Alan Casey, Tiziana Tenuta, Iseult Lynch, Kenneth Dawson, Hugh Byrne, Maria Davoren

Articles

Poly N-isopropylacrylamide and N-isopropylacrylamide / N-tert-butylacrylamide copolymer nanoparticles of 50 to 70 nm were prepared by free radical polymerisation. The particle sizes of the copolymer nanoparticles were measured in the test media MilliQ water, Algae Media, Daphnia Media and Microtox Diluent as a function of temperature. Whereas in MilliQ water the particle size was seen to decrease above the lower critical solution temperature of the thermoresponsive polymer, in the test media it was seen to increase significantly, indicative of aggregation. At the temperatures employed for the ecotoxicological studies all particles, with the exception of the 50:50copolymer existed as nanoparticles, however. …

Nanoantenna Array-Induced Fluorescence Enhancement And Reduced Lifetimes, Reuben M. Bakker, V. P. Drachev, Zhengtong Liu, Hsiao-Kuan Yuan, Rasmus H. Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph Irudayaraj, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

Enhanced fluorescence is observed from dye molecules interacting with optical nanoantenna arrays. Elliptical gold dimers form individual nanoantennae with tunable plasmon resonances depending upon the geometry of the two particles and the size of the gap between them. A fluorescent dye, Rhodamine 800, is uniformly embedded in a dielectric host that coats the nanoantennae. The nanoantennae act to enhance the dye absorption. In turn, emission from the dye drives the plasmon resonance of the antennae; the nanoantennae act to enhance the fluorescence signal and change the angular distribution of emission. These effects depend upon the overlap of the plasmon resonance …

Transport-Based Dopant Metrology In Advanced Finfets, Gabriel P. Lansbergen, Rajib Rahman, Cameron J. Wellard, Jaap Caro, Nadine Collaert, Serge Biesemans, Gerhard Klimeck, Lloyd C. L. Hollenberg, Sven Rogge

Other Nanotechnology Publications

Ultra-scaled FinFET transistors bear unique fingerprint-like device-to-device differences attributed to random single impurities. Through correlation of experimental data with multimillion atom simulations in NEMO 3-D, we can identify the impurity’s chemical species and determine their concentration, local electric field and depth below the Si/SiO2 interface. The ability to model the excited states rather than just the ground states is the critical need. We therefore demonstrate a new approach to atomistic impurity metrology and confirm the assumption of tunneling through individual impurity quantum states.

Atomic-Layer-Deposited Al2o3/Gaas Metal-Oxide-Semiconductor Field-Effect Transistor On Si Substrate Using Aspect Ratio Trapping Technique, Y Q. Wu, M Xu, P. D. Ye, Z Cheng, J Li, J Park, J Hydrick, J Bai, M Carroll, J G. Fiorenza, A Lochtefeld

Birck and NCN Publications

High quality GaAs epilayers grown by metal-organic chemical vapor deposition are demonstrated on a SiO2-patterned silicon substrate using aspect ratio trapping technique, whereby threading dislocations from lattice mismatch are largely reduced via trapping in SiO2 trenches during growth. A depletion-mode metal-oxide-semiconductor field-effect transistor (MOSFET) is demonstrated on a n-doped GaAs channel with atomic-layer deposited Al2O3 as the gate oxide. The 10 mu m gate length transistor has a maximum drain current of 88 mA/mm and a transconductance of 19 mS/mm. The surface mobility estimated from the accumulation drain current has a peak value of similar to 500 cm(2)/Vs, which is …

Full-Band And Atomisic Simulation Of Realistic 40 Nm Inas Hemt, Mathieu Luisier, Neophytos Neophytou, Neerav Kharche, Gerhard Klimeck

Other Nanotechnology Publications

A realistic 40 nm InAs high electron mobility transistor is studied using a two-dimensional, full-band, and atomistic Schr¨odinger-Poisson solver based on the sp3d5s∗ tightbinding model. Bandstructure non-parabolicity effects, strain, alloy disorder in the InGaAs and InAlAs barriers, as well as band-to-band tunneling in the transistor OFF-state are automatically included through the full-band atomistic model. The source and drain contact extensions are taken into account a posteriori by adding two series resistances to the device channel. The simulated current characteristics are compared to measured data and show a good quantitative agreement.

From Nemo1d And Nemo3d To Omen: Moving Towards Atomistic 3-D Quantum Transport In Nano-Scale Semiconductors, Gerhard Klimeck, Mathieu Luisier

Other Nanotechnology Publications

Lessons learned in 15 years of NEMO development starting from quantitative and predictive resonant tunneling diode (RTD) to multi-million atom electronic structure modeling and the path for OMEN are laid out. The recent OMEN capabilities enable realistically large 3D atomistic nano-scale device simulation.

Optical Hyperspace For Plasmons: Dyakonov States In Metamaterials, Zubin Jacob, Evgenii E. Narimanov

Birck and NCN Publications

We show that the subdiffraction imaging behavior observed in the magnifying superlens experiment, [Smolyaninov , Science 317, 1699 (2007)] is due to the hyperbolic dispersion of Dyakonov plasmons supported by the device. These states which are a special case of Dyakonov surface waves [Dyakonov, Sov. Phys. JETP 67, 714 (1988)] exist at the interface of a metal and an anisotropic dielectric giving rise to plasmon beams on resonance. Furthermore, we describe how the unique properties of metamaterial Dyakonov plasmons can be tailored for plasmonic devices.

Electrodeposition Of Nickel Nanowires And Nanotubes Using Various Templates, Asli Ertan, Surendra N. Tewari, Orhan Talu

Chemical & Biomedical Engineering Faculty Publications

Nickel nanotubes and nanowires are grown by galvanostatic electrodeposition in the pores of 1000, 100, and 15 nm polycarbonate as well as in anodised alumina membranes at a current density of 10 mA cm-2. The effects of pore size, porosity, electrodeposition time, effective current density, and pore aspect ratio are investigated. Nickel nanotube structures are obtained with 1000 nm pore size polycarbonate membrane without any prior treatment method. At the early stages of electrodeposition hollow nickel nanotubes are produced and nanotubes turn into nanowires at longer depositon times. As effective current density accounting for the membrane porosity decreases, the axial …

Hydrodynamic Loading Of Microcantilevers Oscillating Near Rigid Walls, Ryan C. Tung, Jana Anirban, Arvind Raman

Birck and NCN Publications

The vibrations of microcantilevers in atomic force microscopes (AFMs) or radio frequency (RF) switches are strongly influenced by the viscous hydrodynamics of the surrounding fluid in the vicinity of a rigid wall. While prior efforts to model this hydrodynamic loading have focused on squeeze film damping effects at high Knudsen and squeeze numbers, the regimes of low Knudsen and squeeze numbers are also very important for which squeeze film models need to be discarded in favor of unsteady Stokes hydrodynamics. We extend the work of Green and Sader [Phys Fluids 17, 073102 (2005); J. Appl. Phys. 98, 114913 (2005)] and …