Nanoscience and Nanotechnology Commons^™

Imaging Using Lateral Bending Modes Of Atomic Force Microscope Cantilevers, A. Caron, U. Rabe, M. Reinstadtler, Joseph A. Turner, W. Arnold

Nebraska Center for Materials and Nanoscience: Faculty Publications

Using scanning probe techniques, surface properties such as shear stiffness and friction can be measured with a resolution in the nanometer range. The torsional deflection or buckling of atomic force microscope cantilevers has previously been used in order to measure the lateral forces acting on the tip. This letter shows that the flexural vibration modes of cantilevers oscillating in their width direction parallel to the sample surface can also be used for imaging. These lateral cantilever modes exhibit vertical deflection amplitudes if the cantilever is asymmetric in thickness direction, e.g., by a trapezoidal cross section.

Attenuation Of Ultrasonic Waves In Rolled Metals, Liyong Yang, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

Scattering of ultrasonic waves in polycrystals with texture is studied in this article. The attenuations of the three wave modes are determined as a function of dimensionless frequency and propagation direction, respectively, for given orientation distribution coefficients (ODCs). The calculation is done in the case of a statistically orthorhombic sample made up of cubic crystallites. The wave propagation and scattering model is formulated by the Dyson equation using an anisotropic Green’s function approach.Within the limits of the first-order smoothing approximation, the Dyson equation is solved in the spatial Fourier transform domain. The results presented are shown to be directional dependent, …

Science For Stewardship: Multidisciplinary Research On Uss Arizona, Matthew A. Russell, Larry E. Murphy, Donald L. Johnson, Timothy J. Foecke, Pamela J. Morris, Raphy Mitchell

Department of Mechanical and Materials Engineering: Faculty Publications

The National Park Service’s Submerged Resources Center and USS Arizona Memorial are conducting and coordinating research directed at understanding the nature and rate of natural processes affecting the deterioration of the USS Arizona in Pearl Harbor, Hawaii. The USS Arizona Preservation Project is designed to be multi-year, interdisciplinary and cumulative, with each element contributing to developing an overall management strategy designed to minimize environmental hazard from fuel oil release and provide the basic research required to make informed management decisions for long-term preservation. The primary project focus is toward acquiring requisite data for understanding the complex corrosion and deterioration processes …

Mechanical Properties Of Carbon Nanotubes Composites, David Hui, Mircea Chipara, Jagannathan Sankar, K. T. Lau

Physics and Astronomy Faculty Publications and Presentations

A critical review of theoretical models aiming to explain the physical properties of composites based on polymeric matrices reinforced with carbon nanotubes is presented. Attention is paid to descriptions based on molecular dynamics, continuum mechanics, and finite element analysis. It is shown that both the continuum mechanics approximation and the finite size element analyses fail to describe composites with very thin interfaces, while the performances of molecular dynamics simulations are still restricted by computer's performances. The limitations of the continuum mechanics approximation are analyzed in detail.

Development Of Nanostructure Based Corrosion-Barrier Coatings On Steel For Transmutation Applications, Biswajit Das

Transmutation Sciences Materials (TRP)

The objective of this project is to develop a novel nanostructure based coating technology that will provide significantly improved corrosion resistance for steel in LBE at elevated temperatures (500 - 600^oC), as well as provide long-term reliability under thermal cycling. The nanostructure based coatings will consist of a layer of nanoporous alumina with the pores filled with an oxidizing metal such as Cr, followed by a capping layer of alumina. Alumina, which is a robust anti-corrosion material, provides corrosion resistance at elevated temperatures. The Cr serves two purposes: (1) it acts as a solid filler material for the …

Highly Selective, Electrically Conductive Monolayer Of Nanoparticles On Live Bacteria, V Berry, Rangaswamy S, Ravi F. Saraf

Papers in Nanotechnology

Using specific peptide−bacteria affinity, a monolayer of 30 nm Au particle is selectively deposited on live bacteria surface to produce electrically conducting bridges spanning over 12 μm. The conductivity of the monolayer network is further improved by over 10-fold by “electric-field annealing”. The annealing process is explained by a percolation model.

Nanotube Magnetism, Yucheng Sui, Ralph Skomski, Kory D. Sorge, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

FePt and Fe3O4 nanotubes are produced by hydrogen reduction in nanochannels of porous alumina templates and investigated by electron microscopy, x-ray diffraction analysis, and magnetic measurements. Loading the templates with a Fe chloride and Pt chloride mixture followed by hydrogen reduction at 560 °C leads to the formation of ferromagnetic FePt nanotubes in the alumina pores. Using a Fe nitrate solution, thermally decomposed at 250 °C and reduced in hydrogen for 2.5 h at the same temperature, yields Fe3O4 tubes. The length of the nanotubes is about 50 mm and their diameters range from about 150 to 220 nm, depending …

Humidity Effects On The Determination Of Elastic Properties By Atomic Force Acoustic Microscopy, D.C. Hurley, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

We have investigated how ambient humidity can affect quantitative measurements of elastic properties on the nanoscale. Using an emerging technique called atomic force acoustic microscopy (AFAM), two samples were examined: a thin film of fluorosilicate glass and a section of borosilicate glass. When experimental results were analyzed using a simple model of the atomic force microscope cantilever dynamics, values of the tip–sample contact stiffness k* increased approximately linearly with relative humidity. The effect is believed to be due to the presence of a humidity-dependent layer of water on the sample. To account for this, the data analysis model was …

Ultrasound Diffusion For Crack Depth Determination In Concrete, S.K. Ramamoorthy, Y. Kane, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

The determination of the depth of surface-breaking cracks in concrete specimens using an ultrasound diffusion technique is discussed. Experiments were carried out on precracked concrete specimens of varying crack depths (0%–40% of the specimen thickness). Contact transducers were placed at the specimen surface with source and receiver separated by the crack. Tone-burst excitations over a frequency range of 400–600 kHz were used. At these frequencies, ultrasound is scattered considerably by the heterogeneities in the concrete. In the limit of many scattering events, the evolution of energy may be modeled as a diffusion process. The arrival of the peak diffuse energy …

Bar Clamp Having Ergonomic Handle, M. Susan Hallbeck, Myung-Chul Jung

Department of Mechanical and Materials Engineering: Faculty Publications

The present invention generally relates to a handle assembly for a hand operable bar clamp having a fixed jaw, a movable jaw and a drive for translating the movable jaw towards the fixed jaw. The assembly includes a handgrip and a trigger handle. The handgrip having an elongated rear portion has a generally rounded surface and being contoured to complement the natural transverse curve pf a human palm. The trigger handle is pivotal with respect to the handgrip. The trigger handle included an elongated front portion having a rounded front surface and being contoured to complement the natural palmer curve …

Interfaces, Volume 7, Issue 1 - Winter 2004

INTERFACES: Newsletter of the Nebraska Center for Materials and Nanoscience

Facility Focus (I): Multipurpose X-Ray System Zeng Named Guggenheim Fellow Sigma Xi Honors to CMRA Faculty, Staff and Students Best Paper Awards Degree of Doctor Honoris Causa Recent Patents Facility Focus(II): Equipment Upgrade in Electron Microscopy CMRA Welcomes Fereydoon Namavar Research Spotlight: Stephen Ducharme Spinning Continuous Fibers for Nanotechnology

Jecp/Sp: A Computer Program For Generating Stereographic Projections, Applicable To Specimen Orientation Adjustment In Tem Experiments, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

In the present work, a computer program was written for generating stereographic projections and was also extended as an application for specimen orientation adjustment in TEM experiments. JECP/SP is a fully functional tool for generating stereographic projections in direct and reciprocal space. JECP/SP has been extended as an application for specimen orientation adjustment using a TEM holder. JECP/SP can be used as a teaching aid for students in crystallography as well as a practical tool for scientists performing TEM experiments.

Development Of Nanostructure Based Corrosion-Barrier Coatings On Steel For Transmutation Applications: Quaterly Report, Biswajit Das

Transmutation Sciences Materials (TRP)

During the past quarter, this project employed one graduate student and two undergraduate student researchers and made the following accomplishments :

• Acquisition of steel samples for experiments

• Design and fabrication of specialized anodization apparatus to accommodate steel samples

• Investigation of adhesiveness of aluminum on steel

• Investigation of effects of anodizing acids on steel to identify most appropriate acid and a suitable barrier material

Microstructural Analysis Of Varistors Prepared From Nanosize Zno, Suresh Pillai, Declan Mccormack, John Kelly, Ramesh Raghavendra

Articles

No abstract provided.

Quantum Mechanical Analysis Of Channel Access Geometry And Series Resistance In Nanoscale Transistors, R. Venugopal, S. Goasguen, S. Datta, M. S. Lundstrom

Other Nanotechnology Publications

We apply a two-dimensional quantum mechanical simulation scheme to study the effect of channel access geometries on device performance. This simulation scheme solves the nonequilibrium Green’s function equations self-consistently with Poisson’s equation and treats the effect of scattering using a simple approximation inspired by Bu ̈ttiker. It is based on an expansion of the device Hamiltonian in coupled mode space. Simulation results are used to highlight quantum effects and discuss the importance of scattering when examining the transport properties of nanoscale transistors with differing channel access geometries. Additionally, an efficient domain decomposition scheme for evaluating the performance of nanoscale transistors …