Engineering Commons^™

Optically Transparent, Scratch-Resistant, Diamond-Like Carbon Coatings, Xiao-Ming He, Deok-Hyung Lee, Michael A. Nastasi, Kevin C. Walter, Michel G. Tuszewski

Department of Mechanical and Materials Engineering: Faculty Publications

A plasma-based method for the deposition of diamond-like carbon (DLC) coatings is described. The process uses a radio-frequency inductively coupled discharge to generate a plasma at relatively low gas pressures. The deposition process is environmentally friendly and scaleble to large areas, and components that have geometrically complicated surfaces can be processed. The method has been used to deposit abherent 100-400 nm thick DLC coatings on metals, glass, and polymers. These coatings are between three and four times harder than steel and are therefore scratch resistant, and transparent to visible light. Boron and silicon doping of the DLC coatings have produced …

Method For Producing Fluorinated Damond-Like Carbon Films, Marko J. Hakovirta, Michael Nastasi, Deok-Hyung Lee, Xiao-Ming He

Department of Mechanical and Materials Engineering: Faculty Publications

Fluorinated, diamond-like carbon (F-DLC) films are produced by a pulsed, glow-discharge plasma immersion ion processing procedure. The pulsed, glow-discharge plasma was generated at a pressure of 1 Pa from an acetylene (CH) and hexafluoroethane (CF) gas mixture, and the fluorinated, diamond-like carbon films were deposited on silicon <100>Substrates. The film hardness and wear resistance were found to be strongly dependent on the fluorine content incorporated into the coatings. The hardness of the F-DLC films was found to decrease considerably when the fluorine content in the coatings reached about 20%. The contact angle of water on the F-DLC coatings was found …

Acuta Enews June 2003, Vol. 32, No. 6

ACUTA Newsletters

In This Issue

ACUTA Annual Conference Headliners

The Value of Volunteering......................... Jeanne Jansenius, Univ. of the South

Leg/Reg lssues Matrix ls Available

Contributing Documents to the ACUTA Resource Library................ Dave Barta, Univ. of Oregon

Load-Lightening Technology Carries Heavy Acronym.......................... Kevin Tanzillo, Dux Public Relations

ACUTA Member Sites to See

Northwestern University Announces C-SPAN/C'SPAN2 Broadcasts via lnternet2

ACUTA Board Report......................... John Bradley, Rensselaer Polytechnic lnstitute

DC Update........................... Whitney Johnson, Retired, Northern Michigan Univ.

Welcome New Members

Paper On Measurement Of The Nanomechanical Properties Of Thin Films Using Afam Receives Recognition, Donna Hurley, Joseph A. Turner, Paul Rice, Joshua Wiehn

Department of Engineering Mechanics: Faculty Publications

NIST researchers are developing atomic force acoustic microscopy (AFAM) methods to quantitatively determine the elastic properties of thin films. The AFAM technique measures the frequencies of an atomic force microscope (AFM) cantilever’s first two flexural resonances while in contact with a material. The indentation modulus, M, of an unknown or test material can then be obtained by comparing the resonant spectra of the test material to those of a reference material. To examine metrology issues for this emerging technique, AFAM results have been compared with those obtained by other methods, such as instrumented indentation. The results show that better agreement …

Jecp/Ed — A Computer Program For Simulation Of Selected-Area And Precession Electron Diffraction Patterns, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

Crystal structure determination by electron crystallography has been very successful in many fields, ranging from organic to inorganic materials. Collection of electron diffraction data is still a crucial step in electron crystallography. The curvature of the Ewald sphere limits the data available in each electron diffraction pattern. The dynamical multi-scattering effect of electron diffraction increases the complexity of the structure determination procedure.

A precession method (Vincent & Midgley, 1994) has been used to solve the crystal structure of AlmFe by Gjonnes and coworker (Berg et al., 1998; Gjonnes et al., 1998). The advantages of precession electron diffraction are (i) the …

Scattering Of Elastic Waves In Damaged Media, Liyong Yang, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

The scattering of elastic waves in a medium with damage from microcracking is discussed. The influence of damage from penny-shaped microcracks within a homogeneous medium is considered. The microcracks are assumed to be randomly oriented and uniformly distributed. Explicit expressions are derived for the attenuation of longitudinal and shear elastic waves in terms of the damage parameter and the effective elastic moduli of the medium. A generalized tensor-based approach is used such that the results are coordinate free. The derivation is based upon diagrammatic methods. The problem is formulated in terms of the Dyson equation, which is solved for the …

Ferromagnetic Domain-Wall Behavior During Reversal And Thermally Activated Antiferromagnetic Reversal In An Exchange-Biased Nio/Nife Bilayer, Z. Y. Liu, Shireen Adenwalla

Materials Research Science and Engineering Center: Faculty Publications

The magnetization reversal mechanism in an exchange-biased NiO/Ni₈₁Fe₁₉ bilayer has been investigated using the magneto-optic Kerr effect and magnetic force microscopy imaging. The asymmetric reversal along the unidirectional axis and the two-step reversal process along the hard axis are promoted by ferromagnetic domain-wall behavior in the decreasing and increasing field branches of the as-deposited hysteresis loop, which is strongly related to the exchange coupling at the interface and the distribution of orientation of the net magnetization at the interface carried by the antiferromagnetic domains. The temperature dependence of the exchange bias and coercivity shows the thermally activated …

Multiscale Modeling Of Hysteretic Phenomena In Magnets „(Invited), Vladimir P. Antropov, Kirill D. Belashchenko

Nebraska Center for Materials and Nanoscience: Faculty Publications

Methodology of multiscale modeling of hysteretic phenomena in magnets is discussed. A practical combination of first-principles, micromagnetic, and microstructural calculations is constructed which allows one to study the hysteretic phenomena in hard magnets. Advantages and shortcomings of this approach are discussed. Multiscale nature of coercivity in CoPt type magnets is elucidated. Two sources of coercivity in polytwinned CoPt type magnets developing at different length scales, domain wall pinning at antiphase boundaries and splitting at twin boundaries, are illustrated for a realistic microstructure

Atomic, Electronic, And Magnetic Properties Of Magnetic Tunnel Junctions, I.I. Oleynik, Evgeny Y. Tsymbal

Materials Research Science and Engineering Center: Faculty Publications

We report results of first-principles density-functional studies of the atomic and electronic structure of Co/Al₂O₃/Co and Co/SrTiO₃/Co magnetic tunnel junctions (MTJs). The atomic structure has been studied for different interface terminations and the interfacial energetics was quantified based on the work of separation. Based on energetics of cohesion, the O-terminated and TiO₂-terminated interfaces were identified as the most stable structures for Co/Al₂O₃/Co and Co/SrTiO₃/Co MTJs, respectively. The electronic structure was analyzed using local densities of states. We found that the electronic structure of the O-terminated Co/Al …

Mechanisms Of Photoluminescence From Silicon Nanocrystals Formed By Pulsed-Laser Deposition In Argon And Oxygen Ambient, X. Y. Chen, Yongfeng Lu, Y. H. Wu, B. J. Cho, M. H. Liu, D. Y. Dai, W. D. Song

Department of Electrical and Computer Engineering: Faculty Publications

We have investigated the different mechanisms of photoluminescence (PL) of silicon nanocrystals due to the quantum confinement effect (QCE) and interface states. Si nanocrystals were formed by pulsed-laser deposition in inert argon and reactive oxygen gas. The collisions between the ejected species greatly influence the morphology of the Si nanocrystals and cause a transition from a film structure to a porous cauliflower-like structure, as the ambient gas pressure increases from 1 mTorr to 1 Torr. The oxygen content of the Si nanocrystals increases with increasing O₂ ambient pressure, and nearly SiO₂ stoichiometry is obtained when the O_{2 …}

Resonant Inversion Of Tunneling Magnetoresistance, Evgeny Y. Tsymbal, Andrei Sokolov, Ildar F. Sabiryanov, Bernard Doudin

Materials Research Science and Engineering Center: Faculty Publications

Resonant tunneling via localized states in the barrier can invert magnetoresistance in magnetic tunnel junctions. Experiments performed on electrodeposited Ni/NiO/Co nanojunctions of area smaller than 0.01 μm² show that both positive and negative values of magnetoresistance are possible. Calculations based on Landauer-Bu¨ttiker theory explain this behavior in terms of disorder-driven statistical variations in magnetoresistance with a finite probability of inversion due to resonant tunneling.

Acuta Enews May 2003, Vol. 32, No. 5

ACUTA Newsletters

In This Issue

Board Approves State of Nominees

Bridging the Digital Gap................................. Jeanne Jansenius, Univ of the South

ACUTA Database of University Telephone Numbers Now Available Be a Moderator or Monitor in Hollywood

Speech-Enabled Auto attendants............................. Detta Donoghue, SDC, lnc.

Tech Talk: SDR: Making Radio All That It Can Be.............................. Kevin Tonzillo, Dux Public Relations

Dues lnvoices Mailed Marshall University Chooses Cell Phones over Landlines ACUTA Board Report............................. John Bradley, Rensselaer Polytechnic lnstitute

DC Update........................... Whitney Johnson, Retired, Northern Michigan Uniuv

Member Needs Assessment Coming Soon.......................Jeri Semer, CAE, Executive Director

Welcome New Members

Micro Goniometer For Scanning Probe Microscopy, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

A goniometer for performing scanning probe microscopy on a substrate surface is disclosed. The goniometer has a cantilever, having a cantilevered end and a supported end and a tip disposed at the cantilevered end of the cantilever. The goniometer also has a block disposed at the supported end of the cantilever. The block has at least one pair of piezoelectric layers, a pair of electrodes disposed about each individual piezoelectric layer such that varying a potential difference applied between the individual electrodes of a pair of electrodes causes the corresponding piezoelectric layer to deform, and a first insulating material disposed …

Ferroelectric Storage Read-Write Memory, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

A memory device including at least one pair of spaced apart conductors and a ferroelectric material between the pair of conductors. The pair of conductors is spaced apart a distance sufficient to permit a tunneling current there between.

Acuta Enews April 2003, Vol. 32, No. 4

ACUTA Newsletters

In This Issue

ACUTA Ruth A. Michalecki Leadership Award

Quantum Encryption........................ Jeanne Jansenius, Univ. of the South

New Toot Turns Students into Technicians....................... Carol Everett Oliver, Everett Comm.

Lead Us Not lnto Network Complication............................. Kevin Tanzillo, Dux Public Relations

Expanded Eligibility for .EDU Domains

Cell Phone Numbers May Soon Be Available via 411 Directory Assistance

ACUTA Board Report........................ John Bradley, Rensselaer Polytechnic institute

DC Update............................. Whitney Johnson, Retired, Northern Michigan Univ.

Progress Report on Telephone Number Database.............................Jeri Semer, CAE, Executive Director

Welcome New Members

Nebraska Blueprint - Spring 2003

Nebraska Blueprint (Student Publication)

Table of Contents:

Editorial: Get involved with the Nebraska Blueprint; Importance of Academic Honesty
Dean's Letter: Integrate engineering into life
Nebraska Blueprint at the ECMA awards: And they said engineers couldn't write...
Achievement: Good News from Construction Management
Nuts and Bolts
Back Page: Construction Systems holds successful internship fair
A Fond Farewell by Adam Holmberg
Reaching Them (While They're Young) by Roxane Gay
A Sense of Place by Roxane Gay
Keeping You Between the Lines by Tom Pryor
Othmer Toys by Thomas Cudd
As Young As You Feel by Thomas Cudd

User Interface Improvement For Mlpq System, Shasha Wu

School of Computing: Dissertations, Theses, and Student Research

This thesis describes the experience of migrating the MLPQ constraint database system, a complex standalone Multiple Document Interface (MDI) application, to a server-based remote accessible application. Centralized, standalone MDI application is a common style for personal software products in Windows. For a database management system, server-based, thin-client computing is a more popular infrastructure. Migrating an existing standalone constraint database application to be a web accessible constraint database server is the main goal of this thesis. This migration process provides a method for the constraint database system to collaborate with other specific applications. We rebuild the desktop MLPQ constraint database system …

Screw Dislocation Interacting With Interface And Interfacial Cracks In Piezoelectric Bimaterials, Xiangfa Wu, Steve Cohn, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Interface and interfacial cracks interacting with screw dislocations in piezoelectric bimaterials subjected to antiplane mechanical and in-plane electrical loadings are studied within the framework of linear piezoelectricity theory. Straight dislocations with the Burgers vector normal to the isotropic basal plane near the interface or interfacial crack are considered. The dislocations are characterized by a discontinuous electric potential across the slip plane and are subjected to a line-force and a line-charge at the core. An explicit solution for the screw dislocation in piezoelectric bimaterial with straight interface is found based on the solution of a similar problem for infinite homogenous medium. …

The Effect Of Plasma Shielding On Dust Particle Interaction In Low Pressure Plasmas, M. E. Marks, P. F. Williams

P. F. (Paul Frazer) Williams Publications

The interaction of charged dust particles in plasma is often modeled assuming a constant charge on each particle with the particle charge determined by requiring zero net current to the particles when they are far apart. In this paper the variation in particle charge is calculated for two-body encounters of dust particles taking into consideration mutual electrostatic shielding and a finite Debye length λ_D . Results are reported for particle radii between 0.0105λ_D and 0.349 λ_D. Work is also calculated as a function of particle separation, and it is shown that dust particle energies greater than …

Variation Of Domain Formation In A 15 Nm Nife Layer Exchange Coupled With Nio Layers Of Different Thicknesses, Z.Y. Liu, Shireen Adenwalla

Materials Research Science and Engineering Center: Faculty Publications

The correlation between ferromagnetic domain formation and exchange bias in a series of NiFe/NiO samples with varying NiO thicknesses has been investigated using the magneto-optic Kerr effect and magnetic force microscopy. Below a critical thickness (15 nm) of NiO, the exchange bias H_E is zero and ripple domains exist in the NiFe layer. Above this critical thickness, cross-tie type domain walls appear concurrently with the appearance of exchange bias. Both the number of cross-tie domain walls and the exchange bias increase with an increase in NiO thickness, reaching a maximum at 35 nm NiO, after which both show a …

Mar 2003, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Foundations Liason Report Development Projects Report Report to the Director

Angular Dependence Of Magnetization Reversal Process In Exchange Coupled Ferromagnetic/Antiferromagnetic Bilayers, Z.Y. Liu, Shireen Adenwalla

Materials Research Science and Engineering Center: Faculty Publications

The angular dependence of the magnetization reversal process in the exchange biased ferromagnetic/antiferromagnetic bilayers has been investigated carefully using the Stoner–Wohlfarth rotation model. Depending strongly on the orientation of the applied field and the competition between the unidirectional and uniaxial anisotropic energies, the magnetization rotation can occur at either the same side or the different sides of the field direction for the decreasing and increasing field branches of the hysteresis loop. The calculated results and the magneto-optical Kerr effect have been used to understand the magnetization reversal process in the NiFe/NiO bilayers, which is caused mainly by the magnetization rotation.

Stability Of Order In Solvent-Annealed Block Copolymer Thin Films, Sanjun Niu, Ravi F. Saraf

Papers in Nanotechnology

ABSTRACT: One way to produce high order in a block copolymer thin film is by solution casting a thin film and slowly evaporating the solvent in a sealed vessel. Such a solvent-annealing process is a versatile method to produce a highly ordered thin film of a block copolymer. However, the ordered structure of the film degrades over time when stored under ambient conditions. Remarkably, this aging process occurs in mesoscale thin films of polystyrene-polyisoprene triblock copolymer where the monolayer of vitrified 15 nm diameter polystyrene cylinders sink in a 20 nm thick film at 22 °C. The transformation is studied …

Natural Convection And Solid Phase Combustion, S. E. Whitney, Hendrik J. Viljoen

Papers in Reaction Kinetics

Self-propagating high-temperature synthesis [SHS] is a combustion process involving two or more solid reactants. The typical SHS configuration consists of a cylindrical preform of mixed powders, placed in an inert gas chamber, and ignited at one end. In past studies, interaction between the solid phase and the ambient gas phase has been limited to heat losses from the solid; the influence of natural convection on the solid phase has never been considered. In this study, computational fluid dynamics [CFD] is used, and it is shown that intense convection flow develops in the proximity of the combustion front. Gas flows adjacent …

Effective Thermal Conductivity Estimates Of Particulate Mixtures, Christiaan Richter, Hendrik J. Viljoen, N.F.J Van Rensburg

Papers in Reaction Kinetics

Several theories have been advanced to estimate effective thermal conductivities of particulate mixtures, but most theories have focused on the dilute case. A method is proposed to estimate the effective thermal con-ductivity coefficient of mixtures of arbitrary concentration. Earlier the authors developed a theory to deter-mine the expected contact area between different species. This theory is employed to determine the Kapitza resistance of the heterogeneous mixture and forms part of an overall theory to estimate the effective thermal conductivity. Results are compared with other theoretical estimates and with experiments.

Acuta Enews March 2003, Vol. 32, No. 3

ACUTA Newsletters

In This Issue

Student Serves Spam on Tufts Network

e Portfolios.............................................. Jeanne Jansenius, Univ. of the South

Take a SIP of this lmportant Protocol........................................ Kevin Tanzillo, Dux Public Relations

Upcoming ACUTA Audio Seminars

ACUTA Member Sites to see

Expanded Eligibility for .EDU Domains

FCC Acts on Local Competition

DC Update...................................... Whitney Johnson, Retired, Northern Michigan Univ.

Survey Results...................................... Jeri Semer, CAE, Executive Director

Board Report...................................... John Bradley, Rensselaer Polytechnic Institute

Welcome New Members

Effective Thermal Conductivity Estimates Of Particulate Mixtures, Christiaan Richter, Hendrik J. Viljoen, N.F.J Van Rensburg

Papers in Physical Properties

Several theories have been advanced to estimate effective thermal conductivities of particulate mixtures, but most theories have focused on the dilute case. A method is proposed to estimate the effective thermal conductivity coefficient of mixtures of arbitrary concentration. Earlier the authors developed a theory to determine the expected contact area between different species. This theory is employed to determine the Kapitza resistance of the heterogeneous mixture and forms part of an overall theory to estimate the effective thermal conductivity. Results are compared with other theoretical estimates and with experiments.

Out-Of-Plane Exchange Coupling Between Epitaxial Ni(50 Å) And Nio(600 Å) Bilayers, Z.Y. Liu, Shireen Adenwalla

Materials Research Science and Engineering Center: Faculty Publications

We have investigated the exchange coupling between an epitaxial Ni (50 Å) film with an out-of-plane magnetic easy axis and a NiO (600 Å) film by polar magneto-optic Kerr-effect measurements. The temperature dependences of exchange field H_E for both as-deposited and field-cooled states exhibit the same blocking temperature T_B~130 °C. The exchange field H_E for the field-cooled state is lower than that for the as-deposited state. The hard-axis in-plane loop shows a much smaller value of H_E. No coercivity enhancement is observed. The data are suggestive of linear coupling across the ferromagnet/antiferromagnet interface.

Transgenic Non-Human Mammals Expressing Human Coagulation Factor Viii And Von Willebrand Factor, Henryk Lubon, William N. Drohan, William H. Velander

Papers in Biotechnology

A non-human transgenic mammalian animal, as described above, contains an exogenous double stranded DNA sequence stably integrated into the genome of the animal, which comprises cis-acting regulatory units operably linked to a DNA sequence encoding human Factor VIII protein and a signal peptide, where the cis-acting regulatory units are active in mammary gland cells and the signal peptide is active in directing newly expressed Factor VIII into the milk of the animal. The promoter may be a milk protein promoter such as for whey acidic protein, casein, lactalbumin, or beta-lactoglobulin promoter. The transgenic mammals are preferably farm animals, for example, …

Orientation Of Self-Assembled Block Copolymer Cylinders Perpendicular To Electric Field In Mesoscale Film, S. Elhadj, J. W. Woody, V. S. Niu, Ravi F. Saraf

Ravi Saraf Publications

The possibility of using self-assembled films of block polymers as templates to fabricate nanoscale structures for devices has attracted great attention towards this class of material. Self-assembly of a block copolymer can be directed by using an electric field to orient features (i.e., ~10-nm-diam cylinders) parallel to the electric field, making the material more attractive as a nanoscale lithography mask. In this letter we describe an approach to influence the electric field orientation phenomena by interfacial effects. As a result, the 15-nm-diam polystyrene cylinders of the polystyrene–polyisoprene–polystyrene triblock copolymer orient perpendicular to the electric field. The described approach along with …