In this article, the relative stability of different high-pressure phases of various cesium halides is studied from first principles and analyzed using the Landau theory of phase transitions.

We explore the feasibility of resurrecting the apparent magnitude-redshift relation for a 'standard candle' to measure the cosmological constant and mass density. We show that type Ia supernovae, if measured with 0.15 mag uncertainty out to a redshift of z = 1, may provide a good standard candle or calibrated candle for this purpose. The recent discovery of probable type Ia supernovae in the redshift range z = 0.3 to 0.5 (Perlmutter et al. 1994a, and 1994b) indicates that the flux of optical photons from these events can be measured this accurately. The 7 distant supernovae discovered to date do not by themselves distinguish between different cosmological models, however the further discovery of about 50 type Ia supernovae at redshifts in the range 0.5 < z {approx} 1.0 could strongly constrain the allowed range of these parameters. We estimate that the follow-up photometry necessary for this measurement would be on the order of 20 - 70 hours of time on a lO-meter class telescope at a site with good seeing.

We are designing an experiment to study physics, engineering, and costing issues of an extended Relativistic Klystron Two-Beam Accelerator (RK-TBA). The experiment is a prototype for an RK-TBA based microwave power source suitable for driving a 1 TeV linear collider. Major components of the experiment include a 2.5-MV, 1.5-kA electron source, a 11.4-GHz modulator, a bunch compressor, and a 8-m extraction section. The extraction section will be comprised of 4 traveling-wave output structures, each generating about 360 MW of rf power. Induction cells will be used in the extraction section to maintain the average beam energy at 5 MeV. Status of the design is presented.

An article written by April M. Washington for the Denton Record-Chronicle that covers two graduate students from UNT, Bader Alruwais and Matthew Mailman. Alruwais received the Prince Bandar ibn Sultan Annual Award for Cultural and Scientific Research and Mailman is conducting a recital performance.

An article from the Fort Worth Star-Telegram written by Clara Herrera. The article covers Brandon Lewis and other students in art classes and the logistics behind what courses are available to them.

Tissue-specific gene expression in mammary epithelium is dependent on the extracellular matrix as well as hormones. There is good evidence that the basement membrane provides signals for regulating beta-casein expression, and that integrins are involved in this process. Here, we demonstrate that in the presence of lactogenic hormones, laminin can direct expression of the beta-casein gene. Mouse mammary epithelial cells plated on gels of native laminin or laminin-entactin undergo functional differentiation. On tissue culture plastic, mammary cells respond to soluble basement membrane or purified laminin, but not other extracellular matrix components, by synthesizing beta-casein. In mammary cells transfected with chloramphenicol acetyl transferase reporter constructs, laminin activates transcription from the beta-casein promoter through a specific enhancer element. The inductive effect of laminin on casein expression was specifically blocked by the E3 fragment of the carboxy terminal region of the alpha 1 chain of laminin, by antisera raised against the E3 fragment, and by a peptide corresponding to a sequence within this region. Our results demonstrate that laminin can direct tissue-specific gene expression in epithelial cells through its globular domain.

We report the development and on-vehicle testing of an engineering prototype zinc/air battery. The battery is refueled by periodic exchange of spent electrolyte for zinc particles entrained in fresh electrolyte. The technology is intended to provide a capability for nearly continuous vehicle operation, using the fleet s home base for 10 minute refuelings and zinc recycling instead of commercial infrastructure. In the battery, the zinc fuel particles are stored in hoppers, from which they are gravity fed into individual cells and completely consumed during discharge. A six-celled (7V) engineering prototype battery was combined with a 6 V lead/acid battery to form a parallel hybrid unit, which was tested in series with the 216 V battery of an electric shuttle bus over a 75 mile circuit. The battery has an energy density of 140 Wh/kg and a mass density of 1.5 kg/L. Cost, energy efficiency, and alternative hybrid configurations are discussed.

The effect of temperature on the kinetics of growth, substrate metabolism, and perchloroethylene (PCE) dechlorination by a methanogenic consortium is reported. In all cases, a simple kinetic model accurately reflected experimental data. Values for the substrate and methane yield coefficients, and the maximum specific growth rate are fairly consistent at each temperature. Also, the substrate and methane yield coefficients show little temperature sensitivity. In contrast, both the maximum specific growth rate and the PCE dechlorination yield coefficient (Y{sub PCE}) are temperature dependent.

The classic Madelung problem is cast into an absolutely convergent form that is readily evaluated by direct lattice summation, revealing a net r{sup {minus}5} range of the net Coulomb potential in ionic crystals and liquids. The realization that Coulomb interactions in condensed systems can actually be rather short ranged (provided the system is overall neutral) leads to the prediction, verified by computer simulations for rocksalt-structure surfaces, that all surfaces in predominantly ionic crystals should be fundamentally reconstructed. The work also provides a conceptual framework for the theoretical treatment of polar surfaces, as demonstrated for the case of the (111) surfaces of NaCl and MgO.

Funds from this award were used to the Workshop in Computational Molecular Biology, `91 Symposium entitled Interface: Computing Science and Statistics, Seattle, Washington, April 21, 1991; the Workshop in Statistical Issues in Molecular Biology held at Stanford, California, August 8, 1993; and the Session on Population Genetics a part of the 56th Annual Meeting, Institute of Mathematical Statistics, San Francisco, California, August 9, 1993.

The Sloan Digital Sky Survey is a world-wide collaboration in astrophysics with contributors from around the United States, Italy, and Japan. Collaborators need to have easy access to current information about the project and the on-going software development. The World Wide Web (WWW) and HTML (HyperText Markup Language meet this need admirably. Our use of the Web can be thought of as providing access to three distinct types of information: (1) the infrastructure of the project, (2) the documentation of actual software used throughout the project, and (3) access to Survey databases. The layout of Web pages is not meant to allow the public to easily surf. Rather, the pages are laid out to permit collaborators to find information efficiently. In keeping with this goal, there is less emphasis on glitz and more on content.

The clean and hydrogen covered (100) and (110) faces of Mo{sub 0.75}Re{sub 0.23} alloy single crystals show 1x1 structures. By means of LEED structure analyses we have determined the interlayer distances as well as the layer concentrations down to the sixth layer. While the clean (110) surface turns out to be nearly bulklike terminated, the clean (100) face is found to exhibit both an extended oscillatory layer relaxation and composition profile. Hydrogen adsorption at low temperatures does not alter the composition profile and removes the small remaining relaxation for the (110) surface. In case of the (100) face a substancial reduction of the relaxation is observed for the outermost layer distances as well, while deeper layer relaxations are preserved indicating a strong coupling off relaxation and composition profiles. Hydrogen is found to adsorb in quasi-threefold coordinated sites for the (110) and bridge sites for the (100) face.

A multiscale four-dimensional data assimilation technique is incorporated into a mesoscale model and evaluated using meteorological and tracer data collected during the Atmospheric Studies in Complex Terrain (ASCOT) field experiment in the winter of 1991. The mesoscale model is used to predict the interaction of synoptically-driven flows and small-scale circulations influenced by terrain along the Front Range in Colorado in the vicinity of the Rocky Flats Plant for four nocturnal periods during the ASCOT field experiment. Data assimilation is used to create dynamically consistent analysis fields based on the mesoscale forecasts and the special asynoptic data taken during this experiment. The wind and turbulence quantities produced by the mesoscale model are then used to determine the dispersion of a tracer released from the Rocky Flats Plant for each evening. The mesoscale model is able to qualitatively predict the mesobeta-scale drainage flows from the Front Range into the South Platte River basin; however, the largest forecast errors occurred in a region immediately adjacent to the foothills. As expected, the current data assimilation technique reduced the overall errors in the atmospheric and dispersion calculations while the model generated realistic small-scale circulations not resolved by the data. Still, the model did not capture …

Continuous fiber ceramic matrix composites are being developed for turbine engine components, heat exchangers, and hot-gas filters in fossil energy systems. Reliable application requires nondestructive evaluation (NDE) methods that provide data for quality assurance and inputs to life time prediction models and that aid in process development. NDE developments at Argonne have focused on methods to assess density distribution, fiber orientation (for mechanical properties), and defect detection in both SiC/SiC and A1{sub 2}O{sub 3}/A1{sub 2}O{sub 3} materials. and that also assess the chemical state at fiber/matrix interfaces. 2-D cloth lay-up and 3-D weave CVI-infiltrated SiC/SiC specimens were studied by X-ray imaging methods now under development. Microfocus X-ray computerized tomography (MXCT) methods are being developed to provide these data. Multinuclear Nuclear Magnetic Resonance spectroscopy (13C, 29Si, and 11B) is under development for quantizing B content at fiber/matrix interfaces. Magic angle spinning techniques on SiC/SiC specimens with different coating thicknesses showed that quantification of B at the Interface is achievable. NDE data are being coupled to room- and elevated-temperature fracture studies to evaluate effects of fiber orientation and fiber coating thickness on resulting flaw morphology and mechanical properties of Nicalon-fiber-reinforced SiC matrix composites. Specifically, composites with fiber cloth lay-up sequences of varying …

The thermodynamics of quasi-one-dimensional superconductors in the presence of large magnetic fields is studied. When the quantum effects of the magnetic field are taken into account, several reentrant phases persist at very high fields. In the last reentrant phase, the free energy, the specific heat jump and the excess magnetization are estimated near the critical temperature. In particular, the excess magnetization is found to be paramagnetic as opposed to diamagnetic (in weak fields) and its sign is found to be controlled by the slope of H{sub c2}. This result is further generalized to the entire phase diagram (including all quantum phases) and to different physical systems using general thermodynamic relations which show that the sign of the excess magnetization {Delta}M near H{sub c2}(T) follows dH{sub c2}(T)/dT. These relations provide a scenario for the evolution of the sign of {Delta}M from weak fields to strong fields.

Thin-film optical and non-optical multilayer coatings are deposited onto flexible substrates using a vacuum web coater developed at Pacific Northwest Laboratory. The coater`s primary application is rapid prototyping of multilayer (1) polymer coatings, (2) polymer/metal coatings, (3) ceramic/metal coatings, and (4) hybrid polymer, ceramic, and metal coatings. The coater is fully automated and incorporates polymer evaporation and extrusion heads, high-rate magnetron sputtering cathodes, and e-beam evaporation sources. Polymer electrolytes are deposited by extrusion techniques. Flexible plastic, metal, and ceramic substrates can be coated using roll-to-roll or closed-loop configurations. Examples of multilayer optical coatings demonstrated to date are solar reflectors, heat mirrors, Fabry-Perot filters, and alpha particle sensors. Nonoptical coatings include multilayer magnetic metal/ceramic and lamellar composites.

Recent reports of temperature dependent antiferromagnetic coupling in Fe/Si multilayers have motivated the generalization of models describing magnetic coupling in metal/metal multilayers to metal/insulator and metal/semiconductor layered systems. Interesting dependence of the magnetic properties on layer thickness and temperature are predicted. We report measurements that show the antiferromagnetic (AF) coupling observed in Fe/Si multilayers is strongly dependent on the crystalline coherence of the silicide interlayer. Electron diffraction images show the silicide interlayer has a CsCl structure. It is not clear at this time whether the interlayer is a poor metallic conductor or a semiconductor so the relevance of generalized coupling theories is unclear.

Pacific Northwest Laboratory is developing an application for the Army and the Federal Emergency Management Agency to support emergency management of hazards resulting from the accidental release of chemical agents during their storage or destruction. This application, called the Federal Emergency Management Information System (FEMIS), uses Oracle7.1 in a client/server configuration. At each Army site where FEMIS is deployed, there will be two or more servers and about 25 users on client personal computers (PCs) connected to each server. The Oracle Data Base Management System is configured as a multiserver, distributed data base using partitioning to share information between the Oracle instances. The information in the individual partitioned tables is merged by Union operators to form a set of site-wide views. This data base contains more than 180 tables and about 40 additional site views. Oracle snapshot replication was chosen rather than distributed queries in order to achieve autonomous operation and improve failure tolerance. The presentation will describe this architecture and discuss how the data was partitioned. Some useful techniques for generating the scripts that produce the data base will also be discussed.

LLNL and Texaco are cooperatively developing a physical and chemical treatment method for the conversion of municipal solid waste (MSW) to hydrogen via the steps of hydrothermal pretreatment, gasification and purification. LLNL`s focus has been on hydrothermal pretreatment of MSW in order to prepare a slurry of suitable viscosity and heating value to allow efficient and economical gasification and hydrogen production. The project has evolved along 3 parallel paths: laboratory scale experiments, pilot scale processing, and process modeling. Initial laboratory-scale MSW treatment results (e.g., viscosity, slurry solids content) over a range of temperatures and times with newspaper and plastics will be presented. Viscosity measurements have been correlated with results obtained at MRL. A hydrothermal treatment pilot facility has been rented from Texaco and is being reconfigured at LLNL; the status of that facility and plans for initial runs will be described. Several different operational scenarios have been modeled. Steady state processes have been modeled with ASPEN PLUS; consideration of steam injection in a batch mode was handled using continuous process modules. A transient model derived from a general purpose packed bed model is being developed which can examine the aspects of steam heating inside the hydrothermal reactor vessel. These models …

A one-dimensional biofilm-based reactive transport model is developed to simulate biologically mediated substrate metabolism and contaminant destruction in saturated porous media. The resulting equations are solved by a finite-difference based, three-level, operator-split approach. The numerical solution procedure is stable, easy-to-code, and computationally efficient. As an example problem, biological denitrification and fortuitous CT destruction processes in one-dimensional porous media is studied. The simulation results of the example problem show that the present model can be successfully used to predict biological processes and nutrient/contaminant transport in saturated porous media.

Particle accelerators with demanding alignment requirements face a need for periodic re-surveying of their reference monument systems. At the ALS, significant foundation settling and the necessary relocation of some floor monuments mean that the entire system of over 100 monuments must be re-surveyed to an accuracy of 100 microns at two year intervals. Last Fall, the monument survey was conducted entirely by the in-house Survey and Alignment crew using a simplified instrument mounting system and an inexpensive commercial software package. Precision levels, plummets, theodolites, and an electronic distance measuring system were used with the innovative ``Monopod`` instrument mounting system in a cost effective approach to this critical task.

This paper contains literature from American Power Conference Air Toxics Being Measured Accurately, Controlled Effectively NO{sub x} and SO{sub 2} Emissions Reduced; Surface Condensers Improve Heat Rate; Usable Fuel from Municipal Solid Waste; Cofiring Technology Reduces Gas Turbine Emissions; Trainable, Rugged Microsensor Identifies of Gases; High-Tc Superconductors Fabricated; High-Temperature Superconducting Current Leads; Vitrification of Low-Level Radioactive and Mixed Wastes; Characterization, Demolition, and Disposal of Contaminated Structures; On-Line Plant Diagnostics and Management; Sulfide Ceramic Materials for Improved Batteries; Flywheel Provides Efficient Energy Storage; Battery Systems for Electric Vehicles; Polymer-Electrolyte Fuel Cells for Transportation; Solid-Oxide Fuel Cells for Transportation; Surface Acoustic Wave Sensor Monitors Emissions in Real-Time; Advance Alternative-Fueled Automotive Technologies; Thermal & Mechanical Process; Flow-Induced Vibration & Flow Distribution in Shell-and-Tube Heat Exchangers; Ice Slurries for District Cooling; Advanced Fluids; Compact Evaporator and Condenser Technology; and Analysis of Failed Nuclear Power Station Components.

Highly p-doped ZnTe films have been grown on semi-insulating GaAs (001) substrates by pulsed-laser ablation (PLA) of a stoichiometric ZnTe target in a high-purity N{sub 2} ambient without the use of any assisting (DC or AC) plasma source. Free hole concentrations in the mid-10{sup 19} cm{sup {minus}3} to > 10{sup 20} cm{sup {minus}3} range were obtained for a range of nitrogen pressures The maximum hole concentration equals the highest hole doping reported to date for any wide band gap II-VI compound. The highest hole mobilities were attained for nitrogen pressures of 50--100 mTorr ({approximately}6.5-13 Pa). Unlike recent experiments in which atomic nitrogen beams, extracted from RF and DC plasma sources, were used to produce p-type doping during molecular beam epitaxy deposition, spectroscopic measurements carried out during PLA of ZnTe in N{sub 2} do not reveal the presence of atomic nitrogen. This suggests that the high hole concentrations in laser ablated ZnTe are produced by a new and different mechanism, possibly energetic beam-induced reactions with excited molecular nitrogen adsorbed on the growing film surface, or transient formation of Zn-N complexes in the energetic ablation plume. This appears to be the first time that any wide band gap (Eg > 2 eV) …

A comparison of the neutron and photon dose rates at different locations on the outside surface of the Model AL-RB, Model FL and the AT-400A containers for a given pit load has been done in order to understand the shielding characteristics of these containers. The Model AL-R8 is not certified for transport and is only used for storage of pits, while the Model FL is a certified Type B pit transportation container. The AT-400A is being developed as a type B pit storage and transportation container. The W48, W56 and B83 pits were chosen for this study because of their encompassing features with regard to other pits presently being stored. A detailed description of the geometry and materials of these containers and of the neutron and photon emission spectra from the actinide materials present in the pit have been used in the calculations of the total dose rates. The calculations have been done using the three-dimensional, neutron-photon Monte Carlo code MCNP. The results indicate the need for a containment vessel (CV), as is found in the Model FL and AT-400A containers, in order to assure compliance with 10 CFR 71 regulations. The absence of a CV in the AL-R8 container …