Engineering Commons^™

Effects Of Magnetostatic Coupling On Stripe Domain Structures In Magnetic Multilayers With Perpendicular Anisotropy, K. Janicka, John D. Burton, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

We investigate the effects of magnetostatic interlayer coupling on the formation of magnetic domains in exchange-coupled ferromagnetic films exhibiting perpendicular magnetic anisotropy. Using simple models for the stripe domain structures we investigate how the magnetostatic interlayer interaction affects the domain size. For antiferromagnetically exchange-coupled multilayers, we show that there is a domain overlap due to the magnetostatic interaction which exists only above a critical thickness and below a critical separation between the ferromagnetic films where it is scaled inversely proportional to the antiferromagnetic exchange coupling constant. We show that the magnetostatic coupling is responsible for the periodic “tiger tail” domain …

Developement Of Serum-Free Media In Cho-Dg44 Cells Using A Central Composite Statistical Design, Ananth Parampalli, Kent M. Eskridge, Leonard Smith, Michael M. Meagher, M. C. Mowry, Anuradha Subramanian

Anuradha Subramanian Publications

A serum free medium was developed for the production of recombinant antibody against Botulinum A (BoNTA) using dihydrofolate reductase deficient Chinese Hamster Ovary Cells (CHO-DG44) in suspension culture. An initial control basal medium was prepared, which was similar in composition to HAM’s F12: IMDM (1:1) supplemented with insulin, transeferrin, selenium and a lipid mixture. The vitamin concentration of the basal medium was twice that of HAM’s F12: IMDM (1:1). CHO-DG44 cells expressing S25 antibody grew from 2 x 10⁵ cells to maximum cell density of 1.04 x 10⁶ cells/ml after 5 days in this control medium. A central …

Department Of Biological Systems Engineering Newsletter, Volume 3, Issue 1, June 2007

BSE Department Magazine

Contents:
Award Winning Academic Advisor
Hall of Fame 2007 Leslie W. Jochens, P.E. Leader in the Irrigation Industry
From the Department Head
John Deere Dealership Management Banquet
Alumni Profiles: Mike Henry
The Incredible, Edible Vehicle Competition
Graduation
December 2006 Graduates
May 2007 Graduates
Undergraduate Creative Activities and Research Experiences—UCARE
Honors Convocation
In Memoriam
Alumni News
Faculty News
Comings and Goings

Acuta Enews June 2007, Vol. 36, No. 6

ACUTA Newsletters

ln This lssue

From the President Carmine Piscopo, RCDD, ACUTA President

Board Report .............. Riny Ledgerwood, San Diego State Univ., ACUTA Sec./Treasurer

Tech Talk: Waiting for TechTalk 2.0, the New, lmproved Version................. Kevin Tanzillo, Dux PR

DC Update ... Jeanne Jansenius, Sewanee, The University of the South

Another Hit to the Cabling Budget: Electrician Shortage = Higher Cabling Costs............. Gary Audin

FYI: Useful lnformation from the Campus.................. Student Monitor

Web Tip: What's New at acuta.org?............. Aaron Fuehrer, ACUTA lnformation Technology Manager

Sign Up Today for Preconference Seminars

lnfo Links....................... Randy Hayes, Univ. of Northern lowa

ACUTA Web Seminar: lP Video …

Tuning Magnetic Microstructures Of Reference Layer In Magnetic Tunneling Junctions, L. Yuan, Y. S. Lin, Dexin Wang, Sy-Hwang Liou

Materials Research Science and Engineering Center: Faculty Publications

Magnetic microstructures in the reference layer in magnetic tunneling junctions (MTJs) are tuned by a reversal field under ambient conditions to investigate their effects on the magnetoresistance (MR) and the exchange coupling field (H_E) between the reference layer and the free layer. Magnetization changes in the reference layer can be probed by measuring minor MR loops. The results show the H_E of the minor MR loops versus the applied reversal field changes from negative to positive and crosses zero. These results can be explained by the magnetic inhomogeneities at the interface between anti-ferromagnetic/pinned-ferromagnetic layers, which causes the …

Ferromagnetic Multipods Fabricated By Solution Phase Synthesis And Hydrogen Reduction, Y. C. Sui, Y. Zhao, Sitaram S. Jaswal, Xingzhong Li, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

A simple approach combining pyrolysis and hydrogen reduction is formulated for making ferromagnetic-branched nanostructures called Co multipods. The CoO multipods (branched nanostructures) were produced through the pyrolysis of cobalt-oleate in octadecane at 280 °C with the presence of oleic acid under the protection of pure nitrogen. The angles between the nearest arms are 90°. After the reduction of the branched CoO nanostructures in flowing hydrogen gas in a tubular oven at 290°C, the CoO is reduced to pure cobalt with hexagonal crystal structure and the branched shapes are retained. Anisotropic magnetic properties were found for cobalt multipods on silicon substrates.

Magnetization Reversal In Cubic Nanoparticles With Uniaxial Surface Anisotropy, Ralph Skomski, Xiao-Hui Wei, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

The effect of surface anisotropy on the magnetization reversal in small magnetic particles is investigated. The model considers particles of cubic shape cut from a tetragonal crystal with cube faces in the (001) and equivalent planes. In particles having diameters of less than about 10 nm, the coercivity approaches the Stoner–Wohlfarth limit, but the anisotropy field differs from that of the bulk of the particles. With increasing particle size, the nucleation modes acquire the character of magnetic surface or bulk modes that reduce the coercivity.

Effective Demagnetizing Factors Of Complicated Particle Mixtures, Ralph Skomski, George C. Hadjipanayis, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Demagnetizing factors have been calculated for hierarchical mixtures and dispersions of magnetic particles, such as columns of platelike particles in a matrix and clusters of spherical particles. The theory involves a number of shape and density parameters describing particles, aggregates, and matrix. It approximates distant particles by a homogeneous medium and yields closed and easy-to-use expressions for the effective demagnetizing factor.

Continuous/Cluster-Pinned Recording Media, Ralph Skomski, M. L. Yan, Yinfan Xu, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

We propose and theoretically investigate a new class of nanostructured magnetic recording films, cluster-pinned recording media. The films consist of magnetic clusters exchange coupled to a continuous hard layer with perpendicular anisotropy and low coercivity. Our calculations yield the coercivity and the cross-track correlation length as a function of film thickness and pinning density and strength. The mechanism is very similar to the Gaunt–Friedel pinning in bulk magnets, which differs from ordinary strong pinning by the selfconsistent dependence of wall curvature and coercivity on defect concentration. The main difference is the exponent for the coercivity as a function of the …

Co-Production Of Chemical And Energy Products From Distillers Grains Using Supercritical Fluid Extraction And Thermochemical Conversion Technologies, Lijun Wang, Ajay Kumar, Curtis L. Weller, David D. Jones, Milford A. Hanna

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

Dry-grind technology has become the dominant method for ethanol production. During drygrind ethanol production, roughly one-third of the dry grain mass resides in the dried distillers grains with solubles (DDGS) as by-products (i.e., ∼0.8 kg/L ethanol). The energy content residing in the 0.8 kg DDGS is about 20 MJ, compared to the consumption of 1 MJ electricity and 10 MJ thermal energy for production of each liter of ethanol. A sequential supercritical fluid process with solvents including carbon dioxide, water and ethanol was used to recover high-value chemicals from DDGS. Thermochemical conversion methods were used to convert the DDGS residue …

Early Investment In Soil Conservation Research Continues To Provide Dividends, John E. Gilley, D. C. Flanagan

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Current soil conservation programs are built upon an established research legacy. Hugh H. Bennett, chief of the USDA Soil Conservation Service from 1935 to 1951, was instrumental in the establishment of a network of 35 soil conservation experiment stations (SCES). Research projects were initiated at the SCES in the 1930s to investigate the principal factors causing erosion and to identify the most effective and practical methods of controlling soil loss from agricultural areas. Information obtained from the SCES, and selected other locations, was assembled at the National Runoff and Soil Loss Data Center (NRSLDC) established on the campus of Purdue …

Anisotropic Strain And Phonon Deformation Potentials In Gan, V. Darakchieva, T. Paskova, Mathias Schubert, H. Arwin, P. P. Paskov, B. Monemar, D. Hommel, M. Heuken, J. Off, F. Scholz, B. A. Haskell, P. T. Fini, J. S. Speck, S. Nakamura

Nebraska Center for Materials and Nanoscience: Faculty Publications

We report optical phonon frequency studies in anisotropically strained c-plane- and a-plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E₁(TO), E₁(LO), and E₂ phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c_E1(TO) , c_E1(LO) , and c_E2 are determined. A distinct correlation between anisotropic strain and the A₁(TO) and E₁(LO) …

Traffic Noise Barrier System: U.S. Patent No. Us 7,220,077 B2, Eric C. Humphries, Stephen D. Barratt, Ronald K. Faller, Keith J. Kurz, Dean L. Sicking

Department of Civil and Environmental Engineering: Faculty Publications

A crashworthy traffic noise barrier system for use alongside a path of traffic, the crashworthy traffic noise barrier system comprises a crashworthy longitudinal barrier extending substantially parallel to the path of traffic and a crashworthy traffic noise barrier wall supported by the longitudinal barrier. The crashworthy traffic noise barrier wall includes a plurality of upstanding posts attached to the traffic noise barrier wall, at least one panel supported between each adjacent pair of posts in the plurality of upstanding posts, and at least one longitudinal beam spaced above a top surface of the longitudinal barrier and extending across the plurality …

Characteristics Of Manure Harvested From Beef Cattle Feedlots, William F. Kissinger, Richard K. Koelsch, Galen E. Erickson, Terry J. Klopfenstein

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Open lot cattle production systems present unique challenges for nutrient planning processes. Previous estimates of quantities and characteristics of harvested manure from this type of facility are based upon data from the early 1970s. In addition, harvested manure is impacted by weather, feeding program, season, and pen management decisions. The objectives of this study are to characterize under commercial conditions for open lot beef systems: 1) harvested manure quantities and characteristics; 2) impact of factors such as feeding program, season, and management on harvested manure; and 3) mass balance for nitrogen (N) and phosphorus (P). Data from six commercial feedlots …

Control Of Beam Spot Size In Ellipsometer And The Like Systems, Martin M. Liphardt, Blaine D. Johs, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

System and methodology for controlling a beam spot size where it impinges onto a sample, and/or discriminant selection and analysis of data from detector elements in a two dimensional detector array which correspond to identified regions on a sample.

Broadband Ellipsometer Or Polarimeter System Including At Least One Multiple Element Lens, Martin M. Liphardt, Blaine D. Johs, Jeffrey S. Hale, Craig M. Herzinger, Steven E. Green, Ping He, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Quasi-achromatic multi-element lens(es) which are precisely mounted with respect to one another in a tubular mounting fixture, and the application thereof in focusing, (and optionally re-colliminating), a spectroscopic electromagnetic beam into a very small, chromatically relatively undispersed, area spot on a material system.

System For And Method Of Investigating The Exact Same Point On A Sample Substrate With Multiple Wavelengths, Galen L. Pfeiffer, Martin M. Liphardt, Blaine D. Johs, Craig M. Herzinger, Christopher A. Goeden, Ping He, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed are system for and method of analyzing a sample at substantially the exact same small spot point on a sample with a plurality of wavelengths.

Order-Disorder Transformations In Sm–Co And Sm–Co–Zrc Systems With 2-17 Stoichiometry, Y.Y. Kostogorova-Beller, Jeffrey E. Shield, Matthew J. Kramer

Materials Research Science and Engineering Center: Faculty Publications

This work investigates the order-disorder transformations utilizing time-resolved x-ray diffraction at the Advanced Photon Source. The metastable phases that can form during the order-disorder transformations in the Sm–Co intermetallics have the potential to produce materials with enhanced permanent magnetic properties. The high-temperature experiments transformed the disordered alloys with the TbCu₇-type structure obtained by rapid solidification into the mixture of the hexagonal and rhombohedral ordered structures at 1375 K. The ordering process and the role of the ZrC alloying on the phase formation and ordering transformations were examined. The results showed the formation of shoulders of the fundamental peaks …

System For And Method Of Investigating The Exact Same Point On A Sample Substrate With Multiple Wavelengths, Galen L. Pfeiffer, Martin M. Liphardt, Blaine D. Johs, Craig M. Herzinger, Christopher A. Goeden, Ping He, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed are system for and method of analyzing a sample at Substantially the exact same Small spot point on a sample with a plurality of wavelengths.

Acuta Enews May 2007, Vol. 36, No. 5

ACUTA Newsletters

ln This lssue

Nominees for ACUTA Board of Directors 07-08

From ACUTA Headquarters ....................... Jeri A. Semer, CAE, ACUTA Executive Director

Staff Changes at ACUTA Headquarters

Tech Talk: Med Center Keeps Legacy Equipment Alive in New Network............ Kevin Tanzillo, Dux PR

Overheard on the Listserv: Panic Button Quick Fix ...... Rob McCray, Delaware Tech.& Comm. College

Board Report ............ Riny Ledgerwood, San Diego State Univ. ACUTA Sec./Treasurer

DC Update.......... Jeanne Jansenius, Sewanee, The University of the South

ATlS Releases Standard on Surveillance

Dues Notices Mailed May 1

Technology Policies and User Expectations Focus of 2007 Strategic Leadership Forum

Web Tip: …

A Performance-Based Incentive Program For Asphalt Pavement, Tim Wentz, Satya Peruri, Wayne Jensen, Bruce Fischer

Nebraska Department of Transportation: Research Reports

No abstract provided.

Combined Use Of Oscillating Means And Ellipsometry To Determine Uncorrelated Effective Thickness And Optical Constants Of Material Deposited From A Fluid, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

A combined ellipsometer and oscillator system applied to a chamber for containing fluid, and method of decorrelated determination of thickness and optical constants of depostable materials present in a fluid. In use the ellipsometer determines the product of thickness and optical constant, and the oscillator system changes frequency of oscillation proportional to the thickness of material deposited upon a surface of an element therein.

Interface Proximity Effects In Current-Perpendicular-To-Plane Magnetoresistance, R.J. Baxter, David G. Pettifor, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

Using a tight-binding model that takes into account a realistic electronic band structure and includes defect scattering we investigate spin-dependent transport in Co/Cu/Co trilayers when current flows perpendicular to the plane. We show that resistance of the Co/Cu interface depends on the proximity of another interface, which makes the parameters characterizing the spin-dependent interface resistance AR_F/N^* and γ_F/N, to be dependent on the layer thickness separating the two interfaces. This leads to a decrease in the measurable quantity SR=√(AR_AP)(AR_AP-AR_P) with the Cu layer thickness and, therefore, …

Elasticity Of Planar Fiber Networks, X.-F. Wu, Yuris A. Dzenis

Nebraska Center for Materials and Nanoscience: Faculty Publications

A micromechanics model is proposed for the elasticity of planar fiber networks (FNs). The FN is created by random deposition of linearly elastic straight rods within a region. The rods are bonded rigidly at contacts. Under external in-plane loading, the FN deformation consists of fiber bending, elongation, and contraction. An effective constitutive relation for fiber network is developed by averaging the strain energy dissipated by all possible fiber deformations in all directions. Numerical calculations are performed to analyze the effects of fiber aspect ratio and fiber concentration on the effective stiffness of the planar random FN. Finite element analysis (FEA) …

Guided Self-Assembly Of Diblock Copolymer Thin Films On Chemically Patterned Substrates, Xiang-Fa Wu, Yuris A. Dzenis

Nebraska Center for Materials and Nanoscience: Faculty Publications

We study the guided self-assembly of symmetric/asymmetric diblock copolymer (BCP) films on heterogeneous substrates with chemically patterned surface by using a coarse-grained phase-separation model. During the procedure, the free energy employed for the BCP films was modeled by the Ginzburg-Landau free energy with nonlocal interaction, and the flat, chemically patterned surface was considered as a heterogeneous surface with short-range interaction with the BCP molecules. The resulting Cahn-Hilliard equation was solved by means of an efficient semi-implicit Fourier-spectral algorithm. Effects of pattern scale, surface chemical potential, and BCP asymmetry on the self-assembly process were explored in detail and compared with those …

Calibration Of Atomic Force Microscope Cantilevers Using Piezolevers, Saltuk B. Aksu, Joseph A. Turner

Department of Engineering Mechanics: Faculty Publications

The atomic force microscope (AFM) can provide qualitative information by numerous imaging modes, but it can also provide quantitative information when calibrated cantilevers are used. In this article a new technique is demonstrated to calibrate AFM cantilevers using a reference piezolever. Experiments are performed on 13 different commercially available cantilevers. The stiff cantilevers, whose stiffness is more than 0.4 N/m, are compared to the stiffness values measured using nanoindentation. The experimental data collected by the piezolever method is in good agreement with the nanoindentation data. Calibration with a piezolever is fast, easy, and nondestructive and a commercially available AFM is …

Robot For Surgical Applications: United States Patent No. Us 7,199,545 B2, Dmitry Oleynikov, Shane Farritor, Adnan Hadzialic, Stephen R. Platt

Department of Mechanical and Materials Engineering: Faculty Publications

The present invention provides a robot for use inside an open abdominal cavity during minimally-invasive surgery. The robot may include various sensors, imaging devices or manipulators.

Acuta Enews April 2007, Vol. 36, No. 4

ACUTA Newsletters

In This Issue

From the President.................... Carmine Piscopo, RCDD, ACUTA President

Nominate for ACUTA Ruth A. Michalecki Award

Board Report ............................ Riny Ledgerwood, San Diego State Univ., ACUTA Sec./Treasurer

Tech Talk: CMDB ls a Step Toward Seeing All, Knowing All.................. Kevin Tanzillo, Dux PR

DC Update................... Jeanne Jansenius, Sewanee, The University of the South

National LambdaRail and lnternet2 Renew Merger Discussions

FYI: Useful lnformation from the Campus............... Student Monitor

Web Tip: RSS Feed Technology............ Aaron Fuehrer, ACUTA lnformation Technology Manager

lnfo Links................ Randy Hayes, Univ of Northern lowa

Grants to Higher Ed from Microsemi

Welcome New Members

Computational Constitutive Model For Predicting Nonlinear Viscoelastic Damage And Fracture Failure Of Asphalt Concrete Mixtures, Yong-Rak Kim, D. H. Allen, D. N. Little

Department of Engineering Mechanics: Faculty Publications

A computational constitutive model was developed to predict damage and fracture failure of asphalt concrete mixtures. Complex heterogeneity and inelastic mechanical behavior are addressed by the model by using finite-element methods and elastic– viscoelastic constitutive relations. Damage evolution due to progressive cracking is represented by randomly oriented interface fracture, which is governed by a newly developed nonlinear viscoelastic cohesive zone model. Computational simulations demonstrate that damage evolution and failure of asphalt concrete mixtures is dependent on the mechanical properties of the mixture. This approach is suitable for the relative evaluation of asphalt concrete mixtures by simply employing material properties and …

Interfaces, Volume 9, Issue 1 - Spring 2007

INTERFACES: Newsletter of the Nebraska Center for Materials and Nanoscience

CONTENTS
From the Director
Facility Focus: Crystallography
Recent Achievements of Center Researchers
Catalysts For Carbon Monoxide Conversion
NCMN Welcomes Li Tan
Research Spotlight: Christian Binek
LNK Chemsolutions Receives Funding