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Advanced electrodialysis and pervaporation for fermentation-derived organic acids production. (open access)

Advanced electrodialysis and pervaporation for fermentation-derived organic acids production.

Lactate esters produced from carbohydrate have potential markets as nontoxic replacements for halogenated and toxic solvents and as feedstocks for large-volume chemicals and polymers. Argonne National Laboratory has developed a novel process for the production of high-purity lactate esters from carbohydrate. The process uses advanced electrodialysis and pervaporation technologies to overcome major technical barriers in product separation; more specifically, the process involves cation elimination without the generation of salt waste and efficient esterification for final purification. This patented process requires little energy input, is highly efficient and selective, eliminates the large volumes of salt waste produced by conventional processes, and significantly reduces manufacturing costs. The enabling membrane separation technologies make it technically and commercially feasible for lactate esters to penetrate the potential markets.
Date: November 18, 1998
Creator: Tsai, S. P.
System: The UNT Digital Library
Applications and advances of positron beam spectroscopy (open access)

Applications and advances of positron beam spectroscopy

Over 50 scientists from DOE-DP, DOE-ER, the national laboratories, academia and industry attended a workshop held on November 5-7, 1997 at Lawrence Livermore National Laboratory. Workshop participants were charged to address two questions: Is there a need for a national center for materials analysis using positron techniques and can the capabilities at Lawrence Livermore National Laboratory serve this need. To demonstrate the need for a national center, the workshop participants discussed the technical advantages enabled by high positron currents and advanced measurement techniques, the role that these techniques would play in materials analysis and the demand for the data. Livermore now leads the world in materials analysis capabilities by positrons due to developments in response to demands of stockpile stewardship. The Livermore facilities now include the world`s highest current beam of keV positrons, a scanning pulsed positron microprobe under development capable of three dimensional maps of defect size and concentration, an MeV positron beam for defect analysis of large samples, and electron momentum spectroscopy by positrons. It was concluded that the positron microprobe under development at LLNL and other new instruments that would be relocated at LLNL at the high current keV source are an exciting step forward in providing …
Date: March 18, 1998
Creator: Howell, R., LLNL
System: The UNT Digital Library
Atlas Pulsed Power System: a Driver for Multi-Megagauss Fields (open access)

Atlas Pulsed Power System: a Driver for Multi-Megagauss Fields

Atlas is a pulsed power machine designed for hydrodynamic experiments for the Los Alamos High Energy Density Physics Experimental program. It is presently under construction and should be operational in late 2000. Atlas will store 23 MJ at an erected voltage of 240 kV. This will produce a current of 30 MA into a static load and as much as 32 MA into a dynamic load. The current pulse will have a rise time of {approximately}5{micro}s and will produce a magnetic field driving the impactor liner of several hundred Tesla at the target radius of one to two centimeters. The collision can produce shock pressures of {approximately}15 megabars. Design of the pulsed power system will be presented along with data obtained from the Atlas prototype Marx module.
Date: October 18, 1998
Creator: Cochrane, J. C.; Bartsch, R. R.; Bennett, G. A.; Bowman, D. W.; Davis, H. A.; Ekdahl, C. A. et al.
System: The UNT Digital Library
A Brief Discussion of Radiation Hardening of CMOS Microelectronics (open access)

A Brief Discussion of Radiation Hardening of CMOS Microelectronics

Commercial microchips work well in their intended environments. However, generic microchips will not fimction correctly if exposed to sufficient amounts of ionizing radiation, the kind that satellites encounter in outer space. Modern CMOS circuits must overcome three specific concerns from ionizing radiation: total-dose, single-event, and dose-rate effects. Minority-carrier devices such as bipolar transistors, optical receivers, and solar cells must also deal with recombination-generation centers caused by displacement damage, which are not major concerns for majority-carrier CMOS devices. There are ways to make the chips themselves more resistant to radiation. This extra protection, called radiation hardening, has been called both a science and an art. Radiation hardening requires both changing the designs of the chips and altering the ways that the chips are manufactured.
Date: December 18, 1998
Creator: Myers, D.R.
System: The UNT Digital Library
Brillouin scattering from magnetic excitations in coupled layered systems and dots. (open access)

Brillouin scattering from magnetic excitations in coupled layered systems and dots.

None
Date: May 18, 1998
Creator: Grimsditch, M.
System: The UNT Digital Library
Characterization and durability testing of a glass-bonded ceramic waste form. (open access)

Characterization and durability testing of a glass-bonded ceramic waste form.

Argonne National Laboratory is developing a glass bonded ceramic waste form for encapsulating the fission products and transuranics from the conditioning of metallic reactor fuel. This waste form is currently being scaled to the multi-kilogram size for encapsulation of actual high level waste. This paper will present characterization and durability testing of the ceramic waste form. An emphasis on results from application of glass durability tests such as the Product Consistency Test and characterization methods such as X-ray diffraction and scanning electron microscopy. The information presented is based on a suite of tests utilized for assessing product quality during scale-up and parametric testing.
Date: May 18, 1998
Creator: Johnson, S. G.
System: The UNT Digital Library
Comparison between three different traffic micro-simulations and reality in Dallas (open access)

Comparison between three different traffic micro-simulations and reality in Dallas

It is certainly desirable that transportation forecasting models are correct in the sense that the traffic patterns they predict correspond to what would happen in reality under the circumstances assumed in the forecasting model. Unfortunately, it is notoriously difficult to transform the above common sense statement into a technical specification. Since one cannot run controlled experiments in socio-economic systems, it is usually impossible to check the forecasts. The authors describe three traffic microsimulations which operate at different levels of fidelity. They are used to iteratively generate a self-consistent route-set based upon microsimulation feedback. They compare the simulation results of all three simulations to aggregated turn count data of actual field measurements.
Date: June 18, 1998
Creator: Nagel, K.; Pieck, M.; Simon, P.M. & Rickert, M.
System: The UNT Digital Library
Composite Liner, Multi-Megabar Shock Driver Development (open access)

Composite Liner, Multi-Megabar Shock Driver Development

The multi-megabar shock driver development is a series of experiments in support of the Los Alamos High Energy Density Physics Experimental Program. Its purpose is to develop techniques to impact a uniform, stable, composite liner upon a high Z target to produce a multi-megabar shock for EOS studies. To date, experiments have been done on the Pegasus II capacitor bank with a current of {approximately}12MA driving the impactor liner. The driving field is {approximately}200 T at the target radius of 1cm. Data will be presented on the impactor liner. The driving field is {approximately}200 T at the target radius of 1 cm. Data will be presented on the stability and uniformity of the impactor liner when it impacts the target cylinder. Three experiments have been done with emphasis on liner development. Shock pressures greater than a megabar have been done with emphasis on liner development. Shock pressures greater than a megabar have been produced with an Al target cylinder. A Pt target cylinder should produce shock pressures in th e 5-megabar range.
Date: October 18, 1998
Creator: Cochrane, J. C. Jr.; Bartsch, R. R.; Clark, D. A.; Morgan, D. V.; Anderson, W. E.; Lee, H. et al.
System: The UNT Digital Library
Coulomb excitation of a {sup 78}Rb radioactive beam. (open access)

Coulomb excitation of a {sup 78}Rb radioactive beam.

In order to test the feasibility of Coulomb excitation of radioactive projectiles with low beam energies and intensities, they have produced a secondary radioactive beam of {sup 78}Rb and Coulomb re-excited it. The beam was produced in the fusion evaporation reaction {sup 24}Mg({sup 58}Ni,3pn){sup 78}Rb at a beam energy of 260 MeV, using the Argonne National Laboratory ATLAS accelerator. The residues of interest were separated from other reaction products and non-interacting beam using the Fragment Mass Analyzer (FMA). The beam leaving the FMA was {sup 78}Kr and {sup 78}Rb{sup gs,m1,m2}, which was refocused onto a {sup 58}Ni secondary target. They have extracted a spectrum of {gamma}-rays associated with re-excitation of A = 78 isobars. The re-excitation of stable {sup 78}Kr was observed, which serves as a reference. Gamma-rays associated with excitation of {sup 78}Rb{sup gs,m1,m2} were also seen. The measured yields indicate that all the {sup 78}Rb states are highly deformed.
Date: November 18, 1998
Creator: Schwartz, J.
System: The UNT Digital Library
Design and performance of a laser guide star system for the Keck II telescope (open access)

Design and performance of a laser guide star system for the Keck II telescope

A laser system to generate sodium-layer guide stars has been designed, built and delivered to the Keck Observatory in Hawaii. The system uses frequency doubled YAG lasers to pump liquid dye lasers and produces 20 W of average power. The design and performance results of this laser system are presented.
Date: May 18, 1998
Creator: Friedman, H. W., LLNL
System: The UNT Digital Library
Detection of electron and hole traps in CdZnTe radiation detectors by thermoelectric emission spectroscopy and thermally stimulated conductivity (open access)

Detection of electron and hole traps in CdZnTe radiation detectors by thermoelectric emission spectroscopy and thermally stimulated conductivity

The electrical properties of CdZnTe radiation detectors are largely determined by electron and hole traps in this material. The traps, in addition to degrading the detector performance, can function as dopants and determine the resistivity of the material. Thermoelectric emission spectroscopy and thermally stimulated conductivity are used to detect these traps in a commercially available spectrometer-grade CdZnTe detector, and the electrical resistivity is measured as a function of temperature. A deep electron trap having an energy of 695 meV and cross section of 8 x 10{sup {minus}16}cm{sup 2} is detected and three hole traps having energies of 70 {+-} 20 meV, 105 {+-} 30 meV and 694 {+-} 162 meV are detected. A simple model based on these traps explains quantitatively all the data, including the electrical properties at room temperature and also their temperature dependence.
Date: June 18, 1998
Creator: Lee, E. Y.; Brunett, B. A.; Olsen, R. W.; III, J. M. Van Scyoc; Hermon, H. & James, R. B.
System: The UNT Digital Library
Development of mixed-conducting ceramic membranes for hydrogen separation. (open access)

Development of mixed-conducting ceramic membranes for hydrogen separation.

SrCeO{sub 3}- and BaCeO{sub 3}-based proton conductors have been prepared and their transport properties have been investigated by impedance spectroscopy in conjunction with open circuit voltage and water vapor evolution measurements. BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} exhibits the highest conductivity in a hydrogen-containing atmosphere; however, its electronic conductivity is not adequate for hydrogen separation in a nongalvanic mode. In an effort to enhance ambipolar conductivity and improve interfacial catalytic properties, BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} cermets have been fabricated into membranes. The effects of ambipolar conductivity, membrane thickness, and interfacial resistance on permeation rates have been investigated. In particular, the significance of interfacial resistance is emphasized.
Date: May 18, 1998
Creator: Guan, J.
System: The UNT Digital Library
Development of niobium spoke cavities for a superconducting light-ion Linac. (open access)

Development of niobium spoke cavities for a superconducting light-ion Linac.

This paper reports the development of 350 MHz niobium superconducting cavities for the velocity range 0.2< v/c <0.6. Such cavities could be used to form a linac of exceptional flexibility, capable of efficiently accelerating beams of either protons, deuterons, or any of a wide range of light ions, at intensities sufficient for a production beam for a radioactive beam facility. Results of numerical modeling for several resonator geometries are presented. The design and construction status of prototype niobium cavities is discussed.
Date: November 18, 1998
Creator: Shepard, K. W.
System: The UNT Digital Library
Diode-pumped solid-state laser drivers for inertial fusion energy (open access)

Diode-pumped solid-state laser drivers for inertial fusion energy

This paper reviews work on flashlamp-pumped solid state lasers and discusses diode-pumped solid state lasers, the Mercury laser in particular. It also discusses ICF lasers beyond Mercury.
Date: December 18, 1998
Creator: Bibeau, C; Marshall, C D; Payne, S A & Powell, H T
System: The UNT Digital Library
Distributed radiator, heavy ion driven inertial confinement fusion target with realistic, multibeam illumination geometry (open access)

Distributed radiator, heavy ion driven inertial confinement fusion target with realistic, multibeam illumination geometry

This paper presents a series of heavy ion driven, inertial confinement fusion targets that all have adequate gain (> 50) for inertial fusion energy. These targets are based on the distributed radiator concept in which much of the hohlraum is filled with low density converter material in approximate pressure balance. This target is driven by heavy ion beams with a Gaussian spatial distribution in a multibeam geometry that is consistent with the number of beams needed by the accelerator and the space needed by the final focusing system. Because the optimal ion species and kinetic energy depend on the integrated system of accelerator, final focusing, chamber transport, and target, we have extended the distributed radiator target to accept ions with range of 0.035 g/cm2 to 0.08 g/cm 2. In addition, a �close coupled� version of the target, in which the hohlraum wall is brought in closer to the capsule to increase the coupling efficiency, has produced gain > 130 from 3.3 MJ of beam energy.
Date: September 18, 1998
Creator: Callahan-Miller, D & Tabak, M
System: The UNT Digital Library
Dynamic modulus estimation and structural vibration analysis. (open access)

Dynamic modulus estimation and structural vibration analysis.

Often the dynamic elastic modulus of a material with frequency dependent properties is difficult to estimate. These uncertainties are compounded in any structural vibration analysis using the material properties. Here, different experimental techniques are used to estimate the properties of a particular elastomeric material over a broad frequency range. Once the properties are determined, various structures incorporating the elastomer are analyzed by an interactive finite element method to determine natural frequencies and mode shapes. Then, the finite element results are correlated with results obtained by experimental modal analysis.
Date: November 18, 1998
Creator: Gupta, A.
System: The UNT Digital Library
Electromagnetic and Microstructural Properties of Pure C-Axis Twist Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} Bicrystal Junctions (open access)

Electromagnetic and Microstructural Properties of Pure C-Axis Twist Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} Bicrystal Junctions

Bulk Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi2212) bicrystals containing a single high quality [001] twist grain boundary junction were prepared in order to investigate the orbital symmetry of the superconducting order parameter in highly anisotropic Bi-based high temperature superconductors. The misorientation angles of the bicrystals ranged from 0 to 180{degree}. The microstructure in the vicinity of the junction was characterized using high-resolution, nano-probe analytical microscopy. The authors found that some high angle twist junctions were able to carry a critical current density similar to their constituent single crystals. These results cannot be interpreted in terms of a pure d{sub x{sup 2}-y{sup 2}}-wave order parameter for superconducting Bi2212.
Date: July 18, 1998
Creator: Tsay, Y.; Li, Q.; Zhu, Y.; Suenaga, M.; Gu, G. D. & Koshizuka, N.
System: The UNT Digital Library
Evidence for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} (open access)

Evidence for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}

The first observation of the decay K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} has been reported. The E787 experiment presented evidence for the K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} x 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 18, 1998
Creator: Kettell, S.
System: The UNT Digital Library
EVIDENCE FOR K+ YIELDS P+ VV-. (open access)

EVIDENCE FOR K+ YIELDS P+ VV-.

The first observation of the decay K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}} has been reported. The E787 experiment presented evidence for the K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}}) = 4.2{sub -3.5}{sup +9.7} x 10{sup -10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E7878 data sample, from the 1995-98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collected in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 18, 1998
Creator: Kettell, S.
System: The UNT Digital Library
Explosive Flux Compression: 50 Years of Los Alamos Activities (open access)

Explosive Flux Compression: 50 Years of Los Alamos Activities

Los Alamos flux compression activities are surveyed, mainly through references in view of space limitations. However, two plasma physics programs done with Sandia National Laboratory are discussed in more detail.
Date: October 18, 1998
Creator: Fowler, C. M.; Thomson, D. B. & Garn, W. B.
System: The UNT Digital Library
Fabrication and testing of optics for EUV projection lithography (open access)

Fabrication and testing of optics for EUV projection lithography

EUV Lithography (EUVL) is a leading candidate as a stepper technology for fabricating the ``0.1 {micro}m generation`` of microelectronic circuits. EUVL is an optical printing technique qualitatively similar to DUV Lithography (DUVL), except that 11-13nm wavelength light is used instead of 193-248nm. The feasibility of creating 0.1{micro}m features has been well-established using small-field EUVL printing tools and development efforts are currently underway to demonstrate that cost-effective production equipment can be engineered to perform full-width ring-field imaging consistent with high wafer throughput rates Ensuring that an industrial supplier base will be available for key components and subsystems is crucial to the success of EUVL. In particular, the projection optics are the heart of the EUVL imaging system, yet they have figure and finish specifications that are beyond the state-of-the-art in optics manufacturing. Thus it is important to demonstrate that industry will be able to fabricate and certify these optics commensurate with EUVL requirements. Indeed, the goal of this paper is to demonstrate that procuring EUVL projection optical substrates is feasible. This conclusion is based on measurements of both commercially-available and developmental substrates. The paper discusses EUVL figure and finish specifications, followed by examples of ultrasmooth and accurate surfaces, and concludes with …
Date: March 18, 1998
Creator: Taylor, J. S., LLNL
System: The UNT Digital Library
A Field Theory Approach to Modeling Helical FCG's (open access)

A Field Theory Approach to Modeling Helical FCG's

Often helical flux-compressor generator (FCG) design codes are essentially circuit codes which utilize known equations for parameterizing circuit elements such as armature and stator inductance. The authors present an analytical model that is based more on first principals. The stator inductance is calculated using a definition of inductance in terms of the magnetic vector-potential. The calculation accounts for winding-pitch, bifurcations, and works for any ratio of length to diameter. The currents on the armature are calculated self-consistently and are not assumed to simply 'mirror' the stator currents. Resistive losses and magnetic diffusion losses are calculated less rigorously but they are working on better methods. Details of the model and comparison with experiment will be presented.
Date: October 18, 1998
Creator: Fortgang, C.M.
System: The UNT Digital Library
First tests of a traveling-wave chopper for the ATLAS positive ion linac. (open access)

First tests of a traveling-wave chopper for the ATLAS positive ion linac.

A ten segment traveling-wave chopper has been constructed and successfully tested at 5% of the design 12 MHz repetition rate. The chopper must remove unbunched tails from a partially bunched heavy-ion beam in order to avoid undue emittance growth in the linac and the production of undesirable satellite beam bunches. When poorly bunched beams traverse the traditional sine-wave chopper, it produces unacceptable transverse emittance growth and unnecessary beam loss. These effects are expected to be much reduced in the traveling wave chopper. First tests have confirmed the validity of these claims, clearly showing much reduced transverse emittance growth as compared to the original sine wave chopper and excellent selectivity for the desired beam. Details of these tests will be presented and compared to calculations. Operation of the new chopper at the full 12 MHz rate is the next goal. Development of a driver power supply capable of full CW operation will also be described.
Date: November 18, 1998
Creator: Pardo, R. C.
System: The UNT Digital Library
Fundamental limits on beam stability at the Advanced Photon Source. (open access)

Fundamental limits on beam stability at the Advanced Photon Source.

Orbit correction is now routinely performed at the few-micron level in the Advanced Photon Source (APS) storage ring. Three diagnostics are presently in use to measure and control both AC and DC orbit motions: broad-band turn-by-turn rf beam position monitors (BPMs), narrow-band switched heterodyne receivers, and photoemission-style x-ray beam position monitors. Each type of diagnostic has its own set of systematic error effects that place limits on the ultimate pointing stability of x-ray beams supplied to users at the APS. Limiting sources of beam motion at present are magnet power supply noise, girder vibration, and thermal timescale vacuum chamber and girder motion. This paper will investigate the present limitations on orbit correction, and will delve into the upgrades necessary to achieve true sub-micron beam stability.
Date: June 18, 1998
Creator: Decker, G. A.
System: The UNT Digital Library