Engineering Commons^™

Dielectric Tensor For Interfaces And Individual Layers In Magnetic Multilayer Structures, Xiang Gao, Michael J. Devries, Daniel W. Thompson, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The magneto-optical Kerr response of metallic magnetic multilayers has been studied by determining the dielectric tensors (dielectric functions) for individual layers, including the magnetic and nonmagnetic interfacial layers. The diagonal components of these tensors were determined using in situ ellipsometric analysis, where the ellipsometric data were taken in real time during multilayer deposition. The off-diagonal components were determined by regression fitting magneto-optic polar Kerr rotation and ellipticity data to models supported by electromagnetic theory. The Voigt parameters (ratio between off-diagonal and diagonal components of dielectric tensors) were determined from these model fits. Higher magnitudes for the Voigt parameters were found …

Self-Organization In Porous 6h–Sic, S. Zangooie, John A. Woollam, H. Arwin

Department of Electrical and Computer Engineering: Faculty Publications

Pores in porous 6H–SiC were found to propagate first nearly parallel with the basal plane and gradually change direction and align with the c axis. As a consequence, well-defined columnar pores were formed. It was shown that the rate of change of propagation directions was influenced by the etching parameters, such as hydrofluoric acid concentration and current density. Larger currents resulted in formation of larger pores. Pore sizes were found to increase with depth due to a decrease of the acid concentration. In addition, due to chemical etching effects, larger pore sizes were obtained close to the sample surface.

Phototrophic Anaerobic Lagoons As Affected By Copper And Zinc In Swine Diets, John E. Gilley, Daniel P. Spare, Richard K. Koelsch, Dennis D. Schulte, Phillip S. Miller, Anne M. Parkhurst

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Odor emissions from anaerobic lagoons containing large populations of phototrophic bacteria are usually minimal. This study was conducted to determine whether copper (123 ppm) and zinc (2,310 ppm) in diets fed to weanling pigs for therapeutic purposes affect phototrophic conditions within lagoons. Column reactors containing 47 L of swine lagoon sludge and supernatant were used to represent lagoons. The reactors were placed in an environmental chamber maintained at 24° C. Copper, zinc, and control manure were added to the reactors at a volatile solids loading rate of 128 g_vs m^–3 da^–1 using a hydraulic retention time of …

Fermentation Strategies For Recombinant Protein Expression In The Methylotrophic Yeast Pichia Pastoris, Wenhui Zhang, Mehmet Inan, Michael M. Meagher

Papers in Biochemical Engineering

Fermentation strategies for recombinant protein production in Pichia pastoris have been investigated and are reviewed here. Characteristics of the expression system, such as phenotypes and carbon utilization, are summarized. Recently reported results such as growth model establishment, application of a methanol sensor, optimization of substrate feeding strategy, DOstat controller design, mixed feed technology, and perfusion and continuous culture are discussed in detail.

All-Solid-State Electrochromic Reflectance Device For Emittance Modulation In The Far-Infrared Spectral Region, E. B. Franke, C. L. Trimble, Mathias Schubert, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

All-solid-state electrochromic reflectance devices for thermal emittance modulation were designed for operation in the spectral region from mid- to far-infrared wavelengths (2–40 μm). All device constituent layers were grown by magnetron sputtering. The electrochromic (polycrystalline WO₃), ion conductor (Ta₂O₅), and Li⁺ ion-storage layer (amorphous WO₃), optimized for their infrared (IR) optical thicknesses, are sandwiched between a highly IR reflecting Al mirror, and a 90% IR transmissive Al grid top electrode, thereby meeting the requirements for a reversible Li⁺ ion insertion electrochromic device to operate within the 300 K blackbody emission …

Micro Goniometer For Scanning 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 …

Enhanced Adhesion Between A Vapor Deposited Metal And An Organic Polymer Surface Exhibiting Tailored Morphology, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

Enhanced adhesion between a vapor deposited metal and an organic polymer surface is achieved without utilizing any intermediate surface preparatory steps. The morphology of the polymer surface is tailored to produce mounds and dimples on the surface which leads to a mechanically tougher, interdigitated metal/polymer interface. In the preferred embodiment, a solution of a solvent or solvent system and two or more polymer precursors or polymers or combinations thereof are cast in a film on a substrate and heated to spontaneously form a rough surface due to phase separation. The surface topography of such a film consists of characteristic mounds …

Acuta Enews August 2000, Vol.29, No. 8

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Facile Sol-Gel Synthesis Of Porous Silicas Using Poly(Propylene)Imine Dendrimers As Templates, Gustavo F. Larsen, Edgar Lotero, Manuel Marquez

Gustavo Larsen Publications

Commercially available poly(propylene)imine (DAB-Am-32 and DAB-Am-64) dendrimers were used as single-molecule templates to tailor the porosity of silicas via a nonacidic sol-gel method. X-ray diffraction on both the as-prepared (oven-dried at 373 K) and the calcined (833 K) materials revealed that modest contraction took place on template removal and that the cavities created did not achieve three-dimensional ordering under the current synthesis conditions. Transmission electron microscopy of “Pt-stained” samples supported this picture. A modified Horvath–Kawazoe analysis of the argon adsorption isotherms indicated that DAB-Am-64 is a much more effective template than DAB-Am-32. Pyrolysis and oxidation protocols for template removal are …

Jul 2000, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Midwest Tool Collectors Annual Meeting Camp Creek Thresher's Event North Door Replaced

Acuta Enews July 2000, Vol.29, No. 7

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Optical Properties Of Bulk And Thin-Film Srtio3 On Si And Pt, Stefan Zollner, A. A. Demkov, R. Liu, P. L. Fejes, R.B. Gregory, Prasad Alluri, J. A. Curless, Z. Yu, J. Ramdani, R. Droopad, T. E. Tiwald, J. N. Hilfiker, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

We have studied the optical properties (complex dielectric function) of bulk SrTiO₃ and thin films on Si and Pt using spectroscopic ellipsometry over a very broad spectral range, starting at 0.03 eV [using Fourier transform infrared (FTIR) ellipsometry] to 8.7 eV. In the bulk crystals, we analyze the interband transitions in the spectra to determine the critical-point parameters. To interpret these transitions, we performed band structure calculations based on ab initio pseudopotentials within the local-density approximation. The dielectric function was also calculated within this framework and compared with our ellipsometry data. In the FTIR ellipsometry data, we notice a …

Acuta Enews June 2000, Vol.29, No. 6

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Piezoelectric Sensors/Actuators For Use In Refractory Environments, Hendrik J. Viljoen, Barend R. Jooste

Papers in Reaction Kinetics

Disclosed is a piezoelectric system which demonstrates piezoelectric properties over a large temperature range of from room temperature to approximately 1,360 degrees Centigrade. The piezoelectric system sequentially comprises a first electrically conductive layer, a layer of Ta₂O₅) in other than a monoclinic phase, (preferably orthorhombic demonstrating small X-ray crystallographic < 0 0 1> and < 1 11 0> peaks), and a second electrically conductive layer. A preferred method of fabrication involves sputter deposition of both said layer of Ta₂O₅ and said second electrically conductive layer.

Acuta Enews May 2000, Vol.29, No. 5

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Order–Disorder Effects In Nitrided Sm–Fe Permanent Magnets, B.E. Meacham, Jeffrey E. Shield, D.J. Branagan

Nebraska Center for Materials and Nanoscience: Faculty Publications

Rapidly solidified Sm₁₁Fe₈₉ was observed to form partially ordered Sm₂Fe₁₇. The ordering increased systematically with annealing temperature, reaching an order parameter of 0.8 after annealing at 950 °C for 15 min. The coercivity of the corresponding interstitial compound Sm₂Fe₁₇N_x varied with annealing temperature and thus order parameter. The coercivity reached a maximum for an order parameter of 0.45–5, then dramatically decreased as the order increased. This behavior is characteristic of demagnetization controlled by domain wall pinning by antiphase boundaries.

Apr 2000

Lester F. Larsen Tractor Museum: Planning and Development Documents

State Museum Report Raffle Committee Book Sales Plans

Acuta Enews April 2000, Vol.29, No. 4

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Wind Powering America: Clean Energy For The 21st Century

United States Department of Energy: Publications

Since earliest recorded history, wind power has been used to move ships, grind grain, and pump water. Today, wind power is also being used to provide electricity to homes, schools, businesses, and entire communities. More than half the United States have wind resources that could support the development of utility scale wind power plants.

Geothermal Heat Pumps In K–12 Schools: A Case Study Of The Lincoln, Nebraska Schools, John A. Shonder, Michaela A. Martin, Patrick J. Hughes, Jeff Thornton

United States Department of Energy: Publications

Geothermal heat pumps (GHPs) have been shown to have a number of benefits over other technologies used to heat and cool buildings and provide hot water, combining high levels of occupant comfort with low operating and maintenance costs. Public facilities represent an increasingly important market for GHPs, and schools are a particularly good application, given the large land area that normally surrounds them. Nevertheless, some barriers remain to the increased use of GHPs in institutional and commercial applications. First, because GHPs are perceived as having higher installation costs than other space conditioning technologies, they are sometimes not considered as an …

Immunoaffinity Chomatography, Anuradha Subramanian

Papers in Biotechnology

Recent devclopments in recombinant DNA technology have enabled the synthesis of valuable therapeutic proteins in bacterial cells as well as in novel eucaryotic expression systems. However, the purification of proteins of interest from either the conventional sources, cell culture, or novel routes in a highly purified form necessitates the development of separation tcchniques capable of recovering proteins from these feed streams in a highly purified form (1,2). Purification of therapeutic proteins from biological sources is usually complicated by the presence of endogenous proteins (2). Purification methodologies based on ion exchange or adsorption serve as excellent prepurification steps, but they fail …

Nanofabrication Using Coulomb Crystals: Giving Shape To The Semiconductor Technology Roadmap, S. Bandyopedhyay, P. F. Williams

P. F. (Paul Frazer) Williams Publications

In 1959, Richard Feynman delivered a lecture with the title, “There is Plenty of Room at the Bottom.” The audience was attendees of the American Physical Society meeting at Caltech. What Feynman, a great seer, talked about was using progressively smaller structures for useful purposes such as storing bits of information.
He even offered a $1,000 (US) prize for anyone who could take the information on the page of a book and put in an area 1/25,000 times smaller in linear scale. In 1986, 26 years after Feynman offered the prize, it was won by a Stanford University graduate student. …

Dynamic Fluvial Systems And Gravel Progradation In The Himalayan Foreland, Nicholas Brozovic, Douglas W. Burbank

Daugherty Water for Food Global Institute: Faculty Publications

Although the large-scale stratigraphy of many terrestrial foreland basins is punctuated by major episodes of gravel progradation, the relationships of such facies to hinterland tectonism and climate change are often unclear. Structural reentrants provide windows into older and more proximal parts of the foreland than are usually exposed, and thus provide key insights to earlier phases of foreland evolution. Our magnetostratigraphic studies show that, although the major lithofacies preserved within the Himachal Pradesh structural reentrant in northwestern India resemble Neogene facies in Pakistan, they have a much greater temporal and spatial variability. From 11.5 to 7 Ma, major facies boundaries …

Acuta Enews March 2000, Vol.29, No. 3

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In Situ Ellipsometry Growth Characterization Of Dual Ion Beam Deposited Boron Nitride Thin Films, E. Franke, Mathias Schubert, John A. Woollam, J.-D. Hecht, G. Wagner, H. Neumann, F. Bigl

Department of Electrical and Computer Engineering: Faculty Publications

Pure hexagonal h, as well as mixed-phase cubic/hexagonal c/h boron nitride (BN) thin films were deposited onto [001] silicon substrates using the dual ion beam deposition technique. The BN thin films were grown under UHV conditions at different substrate temperatures and ion beam bombarding parameters. Thin-film growth was monitored using in situ spectroscopic ellipsometry at 44 wavelengths between 420 and 761 nm. The in situ ellipsometric Ψ and Δ data were compared with two-layer growth model calculations for the mixed-phase c/h BN, and with one-layer growth model calculations for pure h-BN growth. In situ data provide information on …

Phase Formation In Hypostoichiometric Sm2Fe17 Alloys Modified With Ti And C, Jeffrey E. Shield, B.E. Meacham

Nebraska Center for Materials and Nanoscience: Faculty Publications

The phase formation, crystallization products, microstructure, and magnetic behavior of Fe-rich Sm–Fe alloys modified with Ti and C have been determined. Alloys of nominal composition (Sm _0.11-xFe _0.89+x) ₉₄Ti ₃C ₃ with x=0, 0.02, and 0.04 were produced by melt spinning. Crystalline phases observed included SmFe ₇ and α -Fe and an increasing amorphous fraction was observed with increasing x. Upon crystallization the amorphous fraction converted to Sm₂Fe₁₇ and a-Fe, with a grain size of 30 nm for the sample with x=0.02. The magnetic measurements of nitrided alloys …

Feb 2000, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

M.H. Pony Raffle Promotional Brochere Inventory and Displays

Acuta Enews February 2000, Vol.29, No. 2

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Ultra High Density Storage Media And Method Thereof, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

A storage media for storing information having a substrate. The substrate has an upper surface and a molecular weight greater than 5,000. Preferably the material is a polymer. The material has a plurality of piles of molecular chains in selected areas formed by pushing the molecular chains of the material on its upper surface to the selected area mechanically with a mechanical tool. The piles represent written information. The mechanical tool is preferably an atomic force microscope. Another aspect of the present invention is a method for storing information having the steps of selecting a material substrate having an upper …

Jan 2000, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

By-Law Amendments Nominations Potential New Signs