Division of labor among the alpha-6 beta-4 integrin, beta-1 integrins and an E3 laminin receptor to signal morphogenesis and beta-casein expression in mammary epithelial cells (open access)

Division of labor among the alpha-6 beta-4 integrin, beta-1 integrins and an E3 laminin receptor to signal morphogenesis and beta-casein expression in mammary epithelial cells

None
Date: June 30, 1999
Creator: Muschler, J.; Lochter, A.; Roskelley, C. D.; Yurchenco, P. & Bissell, M. J.
System: The UNT Digital Library
Duct Systems in Large Commercial Buildings: Physical Characterization, Air Leakage, and Heat Conduction Gains (open access)

Duct Systems in Large Commercial Buildings: Physical Characterization, Air Leakage, and Heat Conduction Gains

None
Date: March 30, 1999
Creator: Fisk, William J.; Delp, Woody W.; Diamond, Rick C.; Dickerhoff, Darryl J.; Levinson, Ronnen M.; Modera, Mark P. et al.
System: The UNT Digital Library
Geometric Correction System Capabilities, Processing, and Application (open access)

Geometric Correction System Capabilities, Processing, and Application

The U.S. Department of Energy's Remote Sensing Laboratory developed the geometric correction system (GCS) as a state-of-the-art solution for removing distortions from multispectral line scanner data caused by aircraft motion. The system operates on Daedalus AADS-1268 scanner data acquired from fixed-wing and helicopter platforms. The aircraft attitude, altitude, acceleration, and location are recorded and applied to the data, thereby determining the location of the earth with respect to a given datum and projection. The GCS has yielded a positional accuracy of 0.5 meters when used with a 1-meter digital elevation model. Data at this level of accuracy are invaluable in making precise areal estimates and as input into a geographic information system. The combination of high-spatial resolution and accurate geo-rectification makes the GCS a unique tool in identifying and locating environmental conditions, finding targets of interest, and detecting changes as they occur over time.
Date: June 30, 1999
Creator: Brewster, S. B.
System: The UNT Digital Library
Superconducting quadrupole magnets cooling system cost estimation (open access)

Superconducting quadrupole magnets cooling system cost estimation

None
Date: November 30, 1999
Creator: Li, N.
System: The UNT Digital Library
Surface Micromachine Microfluidics: Design, Fabrication, Packaging, and Characterization (open access)

Surface Micromachine Microfluidics: Design, Fabrication, Packaging, and Characterization

The field of microfluidics is undergoing rapid growth in terms of new device and system development. Among the many methods of fabricating microfluidic devices and systems, surface micromachining is relatively underrepresented due to difficulties in the introduction of fluids into the very small channels produced, packaging problems, and difficulties in device and system characterization. The potential advantages of using surface micromachining including compatibility with the existing integrated circuit tool set, integration of electronic sensing and actuation with microfluidics, and fluid volume minimization. In order to explore these potential advantages we have developed first generation surface micromachined microfluidic devices (channels) using an adapted pressure sensor fabrication process to produce silicon nitride channels, and the SUMMiT process to produce polysilicon channels. The channels were characterized by leak testing and flow rate vs. pressure measurements. The fabrication processes used and results of these tests are reported in this paper.
Date: June 30, 1999
Creator: Galambos, Paul; Eaton, William P.; Shul, Randy; Willison, Christi Gober; Sniegowski, Jeffrey J.; Miller, Samuel L. et al.
System: The UNT Digital Library
The Diffusion of Simple Penetrants in Tangent Site Polymer Melts (open access)

The Diffusion of Simple Penetrants in Tangent Site Polymer Melts

The diffusive behavior of penetrants in simple polymer melts was investigated by molecular dynamics simulation. For the case where the polymer melt consisted of pearl-necklace chains, the diffusive behavior of the loose pearl penetrants was seen to be qualitatively different than would be expected in realistic models of polymer melts. In particular, there was little or no ''non-Fickiano'' region; the variation of the diffusion coefficient with the penetrant diameter was what one would expect for diffusion through small molecular liquids; and, finally, the long time tail of the velocity auto correlation displayed a ''-3/2'' power law form, also as in the small molecular liquid case. When the chains' backbone motion was further constrained by the introduction of a bond angle potential, the qualitative nature of the penetrant diffusion became more ''polymer-like''. A non-Fickian region developed; the diffusion coefficient varied more rapidly with penetrant diameter; and the velocity autocorrelation function developed a ''-5/2'' power law tail as would be expected for the diffusion of particles with a wide distribution of trapping times.
Date: June 30, 1999
Creator: Rottach, Dana R.; Tillman, Patrick A.; McCoy, John D.; Plimpton, Steven J. & Curro, John G.
System: The UNT Digital Library
Novel SiGe Coherent Island Coarsening: Ostwald Ripening, Elastic Interactions, and Coalescence (open access)

Novel SiGe Coherent Island Coarsening: Ostwald Ripening, Elastic Interactions, and Coalescence

Real-time measurements of island coarsening during SiGe/Si (001) deposition reveal unusual kinetics. In particular, the mean island volume increases superlinearly with time, while the areal density of islands decreases at a faster-than-linear rate. Neither observation is consistent with standard considerations of Ostvvald ripening. We attribute our observed kinetics to the effect of elastic interactions in the densely growing island array. Island coalescence likely plays an important role as well.
Date: June 30, 1999
Creator: Chason, E.; Floro, J. A.; Freund, L. B.; Hwang, R. Q.; Lucadamo, G. A.; Sinclair, M. et al.
System: The UNT Digital Library
Time-dependent beam focusing at the DARHT-II injector diode (open access)

Time-dependent beam focusing at the DARHT-II injector diode

The injector for the second axis of the Dual-Axis Radiographic Hydrotest Facility (DARHT) is being designed and constructed at LBNL. The injector consists of a single gap diode extracting 2{micro}s, 2kA, 3.2 MeV electron beam from a 6.5 inches diameter thermionic dispenser cathode. The injector is powered through a ceramic column by a Marx generator. We also investigated the possibility of extracting a beam current of 4 kA. The focusing system for the electron beam consists of a Pierce electrostatic focusing electrode at the cathode and three solenoidal focusing magnets positioned between the anode and induction accelerator input. The off-energy components (beam-head) during the 400 ns energy rise time are overfocused, leading to beam envelope mismatch and growth resulting in the possibility of beam hitting the accelerator tube walls. The anode focusing magnets can be tuned to avoid the beam spill in the 2kA case. To allow beam-head control for the 4kA case we are considering the introduction of time-varying magnetic focusing field along the accelerator axis generated by a single-loop solenoid magnet positioned in the anode beam tube. We will present the beam-head dynamics calculations as well as the solenoid design and preliminary feasibility test results.
Date: July 30, 1999
Creator: Eylon, S.; Henestroza, E.; Fawley, W. & Yu, S.
System: The UNT Digital Library
Optical Constants of Beryllium from Photoabsorption Measurements for X-Ray Optics Applications (open access)

Optical Constants of Beryllium from Photoabsorption Measurements for X-Ray Optics Applications

Beryllium (Be) has been recently receiving considerable attention as the key material for a range of potential applications in the extreme ultraviolet (EUV) and x-ray region. Most notably, it has been successfully implemented as the spacer material in beryllium-based multilayer mirrors for EUV lithography, achieving experimental reflectivities of about 70% at wavelengths around 11.4 nm. Knowledge of the absorptive and dispersive properties of this material thus becomes important for the modeling of these optics. Experimental photoabsorption results in the region 40-250 eV, derived from transmission measurements on free-standing beryllium foils, are presented in this work. The measured absorption in the region extending a few tens eV below the K edge (111.7 eV) appears to be significantly (up to 50%) lower than the tabulated values. Fine structure above the K edge is also demonstrated in the measurements. These data are incorporated in an updated set for the atomic scattering factors of beryllium, obtained in the range 0.1-30,000 eV. Finally, the Bragg reflectivity of MO/Be multilayer optics is modeled using the new experimental results.
Date: September 30, 1999
Creator: Soufli, R.; Bajt, S. & Gullikson, E.M.
System: The UNT Digital Library
Miscellaneous electricity use in U.S. homes (open access)

Miscellaneous electricity use in U.S. homes

Historically, residential energy and carbon saving efforts have targeted conventional end uses such as water heating, lighting and refrigeration. The emergence of new household appliances has transformed energy use from a few large and easily identifiable end uses into a broad array of ''miscellaneous'' energy services. This group of so called miscellaneous appliances has been a major contributor to growth in electricity demand in the past two decades. We use industry shipment data, lifetimes, and wattage and usage estimates of over 90 individual products to construct a bottom-up end use model (1976-2010). The model is then used to analyze historical and forecasted growth trends, and to identify the largest individual products within the miscellaneous end use. We also use the end use model to identify and analyze policy priorities. Our forecast projects that over the period 1996 to 2010, miscellaneous consumption will increase 115 TWh, accounting for over 90 percent of future residential electricity growth. A large portion of this growth will be due to halogen torchiere lamps and consumer electronics, making these two components of miscellaneous electricity a particularly fertile area for efficiency programs. Approximately 20 percent (40 TWh) of residential miscellaneous electricity is ''leaking electricity'' or energy consumed …
Date: September 30, 1999
Creator: Sanchez, Marla C.; Koomey, Jonathan G.; Moezzi, Mithra M.; Meier, Alan & Huber, Wolfgang
System: The UNT Digital Library
Monte Carlo Simulation of Ferroelectric Domain Structure and Applied Field Response in Two Dimensions (open access)

Monte Carlo Simulation of Ferroelectric Domain Structure and Applied Field Response in Two Dimensions

A 2-D, lattice-Monte Carlo approach was developed to simulate ferroelectric domain structure. The model currently utilizes a Hamiltonian for the total energy based only upon electrostatic terms involving dipole-dipole interactions, local polarization gradients and the influence of applied electric fields. The impact of boundary conditions on the domain configurations obtained was also examined. In general, the model exhibits domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. The model was also extended to enable the simulation of ferroelectric hysteresis behavior. Simulated hysteresis loops were found to be very similar in appearance to those observed experimentally in actual materials. This qualitative agreement between the simulated hysteresis loop characteristics and real ferroelectric behavior was also confirmed in simulations run over a range of simulation temperatures and applied field frequencies.
Date: June 30, 1999
Creator: Potter, B.G., Jr.; Tikare, V. & Tuttle, B. A.
System: The UNT Digital Library
Plasma Damage in p-GaN (open access)

Plasma Damage in p-GaN

The effect of Inductively Coupled Plasma H{sub 2} or Ar discharges on the breakdown voltage of p-GaN diodes was measured over a range of ion energies and fluxes. The main effect of plasma exposure is a decrease in net acceptor concentration to depths of 400-550{angstrom}. At high ion fluxes or energies there can be type conversion of the initially p-GaN surface. Post etch annealing at 900 C restores the initial conductivity.
Date: June 30, 1999
Creator: Cao, X. A.; Dang, G. T.; Hickman, R. A.; Pearton, S. J.; Ren, F.; Shul, R. J. et al.
System: The UNT Digital Library
Interaction of plasmas with intense lasers (open access)

Interaction of plasmas with intense lasers

The interaction of plasmas with intense lasers is an excellent example of how different fields of physics are inter-connected. Invention of the laser and its ongoing development has allowed the creation and study of high temperature, dense matter in the laboratory. The results both advance the underlying plasma science and are relevant to many fields ranging from astrophysics to fusion and nonlinear physics. A brief overview of the interaction physics is given. Selected topics are discussed to illustrate the exciting progress in experimental, theoretical and computational investigations with focused laser intensities up to 10{sup 21} W/cm{sup 2}.
Date: April 30, 1999
Creator: Kruer, W.
System: The UNT Digital Library
One watt initiative: A global effort to reduce leaking electricity (open access)

One watt initiative: A global effort to reduce leaking electricity

Many domestic appliances and commercial equipment consume some electric power when they are switched off or not performing their primary purpose. The typical loss per appliance is low (from 1 to 25 W) but, when multiplied by the billions of appliances in houses and in commercial buildings, standby losses represent a significant fraction of total electricity use. Several initiatives to reduce standby losses have appeared in different parts of the world. One proposal, the 1-watt plan, seeks to harmonize these initiatives by establishing a single target for all appliances. This paper explains the background to the 1-watt plan, identifies some unresolved aspects, and gives some estimates of energy savings.
Date: May 30, 1999
Creator: Meier, Alan K. & LeBot, Benoit
System: The UNT Digital Library
Mass Spectrometry with Cryogenic Detectors (open access)

Mass Spectrometry with Cryogenic Detectors

None
Date: November 30, 1999
Creator: Frank, M.
System: The UNT Digital Library
MHD Modeling of Conductors at Ultra-High Current Density (open access)

MHD Modeling of Conductors at Ultra-High Current Density

In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator we have revisited a problem first described in detail by Heinz Knoepfel. MITLs of previous pulsed power accelerators have been in the 1-Tesla regime. Z's disc transmission line (downstream of the current addition) is in a 100-1200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 we have been investigating conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are ( 1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into our MHD computations. Certain features are strongly dependent on the details of the conductivity model. Comparison with measurements on Z will be discussed.
Date: June 30, 1999
Creator: Asay, J. R.; Desjarlais, M. P.; Douglas, M. R.; Frese, M. H.; Hall, C. A.; Morse, R. L. et al.
System: The UNT Digital Library
Development of a Compact Optical-MEMS Scanner with Integrated VCSEL Light Source and Diffractive Optics (open access)

Development of a Compact Optical-MEMS Scanner with Integrated VCSEL Light Source and Diffractive Optics

In this work the design and initial fabrication results are reported for the components of a compact optical-MEMS laser scanning system. This system integrates a silicon MEMS laser scanner, a Vertical Cavity Surface Emitting Laser (VCSEL) and passive optical components. The MEMS scanner and VCSEL are mounted onto a fused silica substrate which serves as an optical interconnect between the devices. Two Diffractive Optical Elements (DOEs) are etched into the fused silica substrate to focus the VCSEL beam and increase the scan range. The silicon MEMS scanner consists of an actuator that continuously scans the position of a large polysilicon gold-coated shuttle containing a third DOE. Interferometric measurements show that the residual stress in the 500 {micro}m x 1000 {micro}m shuttle is extremely low, with a maximum deflection of only 0.18{micro}m over an 800 {micro}m span for an unmetallized case and a deflection of 0.56{micro}m for the metallized case. A conservative estimate for the scan range is {approximately}{+-}4{degree}, with a spot size of about 0.5 mm, producing 50 resolvable spots. The basic system architecture, optical and MEMS design is reported in this paper, with an emphasis on the design and fabrication of the silicon MEMS scanner portion of the system.
Date: June 30, 1999
Creator: Krygowski, Thomas W.; Reyes, David; Rodgers, M. Steven; Smith, James H.; Warren, Mial; Sweatt, William et al.
System: The UNT Digital Library
Small Wind Turbine Applications: Current Practice in Colorado (open access)

Small Wind Turbine Applications: Current Practice in Colorado

Numerous small wind turbines are being used by homeowners in Colorado. Some of these installations are quite recent while others date back to the federal tax-credit era of the early 1980s. Through visits with small wind turbine owners in Colorado, I have developed case studies of six small wind energy applications focusing on the wind turbine technology, wind turbine siting, the power systems and electric loads, regulatory issues, and motivations about wind energy. These case studies offer a glimpse into the current state-of-the-art of small-scale wind energy and provide some insight into issues affecting development of a wider market.
Date: September 30, 1999
Creator: Green, J.
System: The UNT Digital Library
Dielectric Properties and Depoling Characteristics of Pb(Zr(0.95)Ti(0.05))O(3) Based Ceramics: Near-Critical Grain Size Behavior (open access)

Dielectric Properties and Depoling Characteristics of Pb(Zr(0.95)Ti(0.05))O(3) Based Ceramics: Near-Critical Grain Size Behavior

Chemically prepared Pb(Zr{sub 0.951}Ti{sub 0.949}){sub 0.982}Nb{sub 0.018}O{sub 3} ceramics were fabricated that were greater than 95% dense for sintering temperatures as low as 925 C. Achieving high density at low firing temperatures permitted isolation of the effects of grain size, from those due to porosity, on both dielectric and pressure induced transformation properties. Specifically, two samples of similar high density, but with grain sizes of 0.7 {micro}m and 8.5 {micro}m, respectively, were characterized. The hydrostatic ferroelectric (FE) to antiferroelectric (AFE) transformation pressure was substantially less (150 MPa) for the lower grain size material than for the larger grain size material. In addition, the dielectric constant increased and the Curie temperature decreased for the sample with lower grain size. All three properties: dielectric constant magnitude, Curie point shift, and FE to AFE phase transformation pressure were shown to be semi-quantitatively consistent with internal stress levels on the order of 100 MPa.
Date: September 30, 1999
Creator: Rodriguez, Mark A.; Scofield, Timothy W.; Tuttle, Bruce A.; Voigt, James A.; Yang, Pin & Zeuch, David H.
System: The UNT Digital Library
Numerical simulation of MHD for electromagnetic edge dam in continuous casting. (open access)

Numerical simulation of MHD for electromagnetic edge dam in continuous casting.

A computer model was developed to predict eddy currents and fluid flows in molten steel. The model was verified by comparing predictions with experimental results of liquid-metal containment and fluid flow in electromagnetic (EM) edge dams (EMDs) designed at Inland Steel for twin-roll casting. The model can optimize the EMD design so it is suitable for application, and minimize expensive, time-consuming full-scale testing. Numerical simulation was performed by coupling a three-dimensional (3-D) finite-element EM code (ELEKTRA) and a 3-D finite-difference fluids code (CaPS-EM) to solve heat transfer, fluid flow, and turbulence transport in a casting process that involves EM fields. ELEKTRA is able to predict the eddy-current distribution and the electromagnetic forces in complex geometries. CaPS-EM is capable of modeling fluid flows with free surfaces. Results of the numerical simulation compared measurements obtained from a static test.
Date: March 30, 1999
Creator: Chang, F. C.
System: The UNT Digital Library
NANOMETER PRECISION IN LARGE SURFACE PROFILOMETRY. (open access)

NANOMETER PRECISION IN LARGE SURFACE PROFILOMETRY.

The Long Trace Profiler (LTP) is in use at many synchrotron radiation (SR) laboratories throughout the world and by a number of manufacturers who specialize in fabricating grazing incidence mirrors for SR and x-ray telescope applications. Recent improvements in the design and operation of the LTP system have reduced the statistical error in slope profile measurement to the 1 standard deviation level of 0.3 microradian for 0.5 meter long mirrors. This corresponds to a height error on the order of 10-20 nanometers. This level of performance allows one to measure with confidence the absolute shape of large cylindrical aspheres and spheres that have kilometer radii of curvature in the axial direction. The LTP is versatile enough to make measurements of a mirror in the face up, sideways, and face down configurations. We will illustrate the versatility of the current version of the instrument, the LTP II, and present results from two new versions of the instrument: the in situ LTP (ISLTP) and the Vertical Scan LTP (VSLTP). Both of them are based on the penta prism LTP (ppLTP) principle that utilizes a stationary optical head and moving penta prism. The ISLTP is designed to measure the distortion of high heat …
Date: August 30, 1999
Creator: TAKACS,P.Z.
System: The UNT Digital Library
{sup 129}I Interlaboratory comparison: phase I and phase II (open access)

{sup 129}I Interlaboratory comparison: phase I and phase II

An interlaboratory comparison exercise for {sup 129}I was organized and conducted. Nine laboratories participated in the exercise to either a full or limited extent. In Phase I of the comparison, 11 samples were measured. The suite of samples contained both synthetic ''standard type'' materials (i.e., AgI) and environmental materials. The isotopic {sup 129}I/{sup 127}I ratios of the samples varied from 10{sup {minus}8} to 10{sup {minus}14}. In this phase, each laboratory was responsible for its own chemical preparation of the samples. In Phase I, the {sup 129}I AMS measurements for prepared AgI were in good agreement. However, large discrepancies were seen in {sup 129}I AMS measurements of environmental samples. Because of the large discrepancies seen in the Phase I {sup 129}I intercomparison, a subsequent study was conducted. In Phase II of the {sup 129}I intercomparison, three separate laboratories prepared AgI from two environmental samples (IAEA 375 soil and maples leaves). Each laboratory used its own chemical preparation method with each of the methods being distinctly different. The resulting six samples (two sets of three) were then re-distributed to the participating {sup 129}I AMS facilities and {sup 129}I/{sup 127}I ratios measured. Results and discussion of both the Phase I and Phase II …
Date: September 30, 1999
Creator: Caffee, M W & Roberts, M L
System: The UNT Digital Library
Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}. (open access)

Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}.

None
Date: July 30, 1999
Creator: Bordallo, H. N.; Christianson, A.; Drulis, H.; Havela, L.; Iwasieczko, W.; Kolomiets, A. V. et al.
System: The UNT Digital Library
X-ray diffraction studies using diamond coated rhenium gasket to megabar pressures (open access)

X-ray diffraction studies using diamond coated rhenium gasket to megabar pressures

X-ray diffraction studies at megabar pressures are limited by the sample thickness between the diamond anvils. High strength gaskets are desirable to improve the quality of x-ray diffraction data. We present a technique which employs a microwave plasma chemical vapor deposited diamond layer on one side of a rhenium gasket. As a test case, we show energy dispersive x-ray diffraction data on rare earth metal neodymium to 153 GPa using a synchrotron source. The increased sample thickness results in an unambiguous crystal structure determination of a monoclinic phase in neodymium above 75 GPa. [chemical vapor deposition, diamond, rhenium gasket, x-ray diffraction, neodymium]
Date: September 30, 1999
Creator: Akella, J; Catledge, S A; Chesnut, G N; Prokop, H; Vohra, Y K & Weir, S T
System: The UNT Digital Library