The authors have successfully synthesized highly crystalline, size-selected indirect band-gap nanocrystals (NC) of Si, Ge and MoS{sub 2} in the size range 2-10 nm in inverse micelles and studied their optical absorption and photoluminescence (PL) properties using liquid chromatography. Room temperature, visible PL from these nanocrystals was demonstrated in the range 700-350 nm (1.8-3.5 eV). their experimental results are interpreted in terms of the corresponding electronic structure of the bulk materials and it is demonstrated that these nanocrystals retain bulk-like electronic character to sizes as small as 2 nm, but the absorbance energies are strongly blue-shifted by quantum confinement. The experimental results on Si-NCs are also compared to earlier work on Si clusters grown by other techniques and to the predictions of various model calculations. Currently, the wide variations in the theoretical predictions of the various models along with considerable uncertainties in experimental size determination for clusters less than 3-4 nm, make it difficult to select the best model.

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.

Weekly newspaper from Alvin, Texas that includes local, state, and national news along with advertising.

The ARAC Client System allows users (such as emergency managers and first responders) with commonly available desktop and laptop computers to utilize the central ARAC system over the Internet or any other communications link using Internet protocols. Providing cost-effective fast access to the central ARAC system greatly expands the availability of the ARAC capability. The ARAC Client system consists of (1) local client applications running on the remote user's computer, and (2) ''site servers'' that provide secure access to selected central ARAC system capabilities and run on a scalable number of dedicated workstations residing at the central facility. The remote client applications allow users to describe a real or potential them-bio event, electronically sends this information to the central ARAC system which performs model calculations, and quickly receive and visualize the resulting graphical products. The site servers will support simultaneous access to ARAC capabilities by multiple users. The ARAC Client system is based on object-oriented client/server and distributed computing technologies using CORBA and Java, and consists of a large number of interacting components.

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the Federal Aviation Administration's (FAA) decision to allow the use of personal computer-based aviation training devices (PCATD), focusing on: (1) the process and information FAA used in deciding to approve the use of personal computer devices for 10 hours of instrument training; and (2) what is known about the training effectiveness of these devices and their long-term impact on a pilot's ability to fly safely."

Correspondence issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on the average and median amount of all homestead exemptions claimed by debtors in the Northern District of Texas and the Southern District of Florida, focusing on: (1) information on debtors' use of the homestead exemption in these two districts; and (2) data on the number of personal chapter 7 bankruptcy cases closed in calendar year 1998 in the remaining five districts in Texas and Florida."

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

The Silicon Vertex Tracker (SVT) is presently being built as part of CDF upgrades. It is the online tracker which will reconstruct 2D tracks using information from the Silicon Vertex Detector (SVXII) and the Central Outer Chamber (COT). The precision measurement of the track impact parameter will allow to select high statistics b samples at trigger level and attack the study of CP violation in the b sector (i.e. in the B⁰_d {yields} {pi}⁺{pi}^- decay) and of B⁰_s mixing. We discuss the overall architecture, algorithms and hardware implementation of the system.

Sandia National Laboratories is developing polyurethane foam as a chemical grout for lost circulation zones. In past work polyurethane foam was tried with limited success in laboratory tests and GDO sponsored field tests. Goals were that the foam expanded significantly and harden to a chillable firmness quickly. Since that earlier work there have been improvements in polyurethane chemistry and the causes of the failures of previous tests have been identified. Recent success in applying pure solution grouts (proper classification of polyurethane--Naudts) in boreholes encourages reevaluating its use to control lost circulation. These successes include conformance control in the oil patch (e.g. Ng) and darn remediation projects (Bruce et al.). In civil engineering, polyurethane is becoming the material of choice for sealing boreholes with large voids and high inflows, conditions associated with the worst lost circulation problems. Demonstration of a delivery mechanism is yet to be done in a geothermal borehole.

This conceptual design report documents the redesign of the IPSS and the OIP in the 105 KW Basin south loadout pit due to a postulated cask drop accident, as part of Project A.5/A.6, Canister Transfer Facility Modifications. Project A.5/A.6 involves facility modifications needed to transfer fuel from the basin into the cask-MCO. The function of the IPSS is to suspend, guide, and position the immersion pail. The immersion pail protects the cask-MCO from contamination by basin water and acts as a lifting device for the cask-MCO. The OIP provides operator access to the south loadout pit. Previous analyses studied the effects of a cask-MCO drop on the south loadout pit concrete structure and on the IPSS. The most recent analysis considered the resulting loads at the pit slab/wall joint (Kanjilal, 1999). This area had not been modeled previously, and the analysis results indicate that the demand capacity exceeds the allowable at the slab/wall joint. The energy induced on the south loadout pit must be limited such that the safety class function of the basin is maintained. The solution presented in this CDR redesigns the IPSS and the OIP to include impact-absorbing features that will reduce the induced energy. The impact …

This Corrective Action Decision Document (CADD) has been prepared for Corrective Action Unit (CAU) 486, Double Tracks Radiological Safety (RADSAFE) Area (DTRSA) in accordance with the Federal Facility Agreement and Consent Order (FFACO) of 1996 that was agreed to by the U.S. Department of Energy, Nevada Operations Office (DOE/NV); the Nevada Division of Environmental Protection (NDEP); and the U.S Department of Defense (FFACO, 1996). The CADD provides or references the specific information necessary to recommend a preferred corrective action for the single Corrective Action Site (CAS), 71-23-001-71DT, within CAU 486. Corrective Action Unit 486 is located on the Nellis Air Force Range 71 North, west of the Tonopah Test Range (TTR), Nevada. The TTR, located in the Nellis Air Force Range, is approximately 140 miles (mi) northwest of Las Vegas, Nevada (Figure 1-1). The DTRSA is located on the west side of the Cactus Range approximately 5 mi southwest of the Cactus Spring gate at the intersection of the Cactus Spring Road and the Double Tracks Control Point Road (Figure 1-2).

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High-temperature superconducting (HTS) cable systems for power transmission are under development that will use pressurized liquid nitrogen to provide cooling of the cable and termination hardware. Southwire Company and Oak Ridge National Laboratory have been operating a prototype HTS cable system that contains many of the typical components needed for a commercial power transmission application. It is being used to conduct research in the development of components and systems for eventual commercial deployment. The cryogenic system was built by Air Products and Chemicals, Allentown, Pennsylvania, and can circulate up to 0.35 kg/s of liquid nitrogen at temperatures as low as 67 K at pressures of 1 to 10 bars. Sufficient cooling is provided for testing a 5-m-long HTS transmission cable system that includes the terminations required for room temperature electrical connections. Testing of the 5-m HTS transmission cable has been conducted at the design ac conditions of 1250 A and 7.5 kV line to ground. This paper contains a description of the essential features of the HTS cable cryogenic system and performance results obtained during operation of the system. The salient features of the operation that are important in large commercial HTS cable applications will be discussed.

The authors performed small-angle neutron scattering experiments on the bulk amorphous alloy Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (Vit1{reg_sign}) and on further alloys, where the ZrTi and CuBe content have been changed, following the tie-line in the direction of Zr{sub 46.8}Ti{sub 8.2}Cu{sub 7.5}Ni{sub 10}Be{sub 27.5} (Vit4{reg_sign}). The SANS data of the samples, preannealed at temperatures between 330 C and 390 C, show interference peaks giving evidence for spatially correlated arrangements of inhomogeneities. The Q values of the interference peaks, Q{sub max}, decrease with increasing annealing temperature T{sub a} and, at a given annealing temperature, with composition following the tie-line from Vit1 to Vit4. They find that, in two distinguished regimes, the data follow a relation 1/L{sup 2} {proportional_to} T{sub a} as predicted by Cahn's theory (L = 2{pi}/Q{sub max} is the wavelength of the decomposition), with a crossover at the glass transition temperature T{sub g} = 350 C. The authors explain the crossover by different diffusion mechanisms below and above T{sub g}.

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed: (1) the Navy's 1997 antisubmarine warfare (ASW) assessment; (2) the role and funding influence of the Navy's recently established Antisubmarine Warfare Requirements Division; and (3) whether the assessment is supported by rigorous analysis of ASW shortfalls and capabilities and establishes priorities among ASW programs, as directed by congressional conferees on the 1997 National Defense Authorization Act."

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on the Department of Defense's (DOD) efforts to reduce the infrastructure that supports initial pilot training, focusing on: (1) DOD's prior efforts to reduce aircraft training infrastructure; (2) plans for expanding pilot training capacity; and (3) the likelihood of further consolidations."

In continuation of our effort to develop single buffer layer architectures for YBCO (YBa₂Cu₃O<sub>7-<font face="symbol">g</font>) coated tape conductors, we have studied RE₂O₃ (RE = Y, and rare earths) as candidate materials. Three types of crystal structures including the preferred cubic phase are known for the rare earth oxides. High quality simple cubic RE₂O₃ buffer layers were grown epitaxiahy on {100}<001> textured Ni substrates using both reactive evaporation and sol-gel processing. Detailed X-ray studies have shown that the Y₂O₃, Eu₂O₃, Gd₂O₃, and Yb₂O₃ were grown with a single epitaxial orientation. SEM micrographs indicated that both e-beam and sol-gel grown films were dense, continuous and crack free. High J_c YBCO films were grown on RE₂O₃-buffered Ni substrates with sputtered cap layers. Two new alternative buffer layer architectures were developed. A high J_c of 1.8 MA/cm² at 77 K and self-field was obtained on YBCO films with a layer sequence of YBCO (pulsed laser deposition)/Yb₂O₃ (sputtered)/Y₂O₃ (e-beam)/Ni. Also, a high J_c of over 1 MA/cm² at 77 K and self-field was obtained on YBCO films with a layer sequence of YBCO (ex-situ BaF₂ process)/CeO₂ (sputtered)YSZ sputtered)/RE₂O₃ (sol-gel or e-beam)Ni. The performance of sol-gel grown buffers approached the quality of e-beam grown buffers.

The design of an adaptive wavefront control system for a high-power Nd:Glass laser will be presented. Features of this system include: an unstable resonator in confocal configuration, a multi-module slab amplifier, and real-time intracavity adaptive phase control using deformable mirrors and high-speed wavefront sensors. Experimental results demonstrate the adaptive correction of an aberrated passive resonator (no gain).

The Savannah River Site (SRS) has a wide variety of nuclear production facilities that include chemical processing facilities, machine shops, production reactors, and laboratories. Current safety documentation must be maintained for the nuclear facilities at SRS. Fire Risk Analyses (FRAs) are used to support the safety documentation basis. These FRAs present the frequency that specified radiological and chemical consequences will be exceeded. The consequence values are based on mechanistic models assuming specific fire protection features fail to function as designed.

In this paper, a single-stage G-M refrigerator with the regenerator set outside the cylinder is presented. The experimental system for testing the performance of the cryocooler was constructed. The lowest temperature was 14K when the operating frequency was 0.6 Hz. The cooling capacity of 4.4W has been obtained at 20K. The effects of operating parameters of the refrigerator on cooling performance were also experimentally studied.

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.

The use of unattended monitoring systems for monitoring the status of high value assets and processes has proven to be less costly and less intrusive than the on-site inspections which they are intended to replace. However, these systems present a classic information overload problem to anyone trying to analyze the resulting sensor data. These data are typically so voluminous and contain information at such a low level that the significance of any single reading (e.g., a door open event) is not obvious. Sophisticated, automated techniques are needed to extract expected patterns in the data and isolate and characterize the remaining patterns that are due to undeclared activities. This paper describes a data analysis engine that runs a state machine model of each facility and its sensor suite. It analyzes the raw sensor data, converting and combining the inputs from many sensors into operator domain level information. It compares the resulting activities against a set of activities declared by an inspector or operator, and then presents the differences in a form comprehensible to an inspector. Although the current analysis engine was written with international nuclear material safeguards, nonproliferation, and transparency in mind, since there is no information about any particular facility …

We have been successful in adapting Fourier transform (FT) Raman accessories and spectrophotometers for sensitive measurements of the photoluminescence (PL) spectra of photovoltaic materials and devices. In many cases, the sensitivity of the FT technique allows rapid room-temperature measurements of weak luminescence spectra that cannot be observed using dispersive PL spectrophotometers. We present here the results of a number of studies of material and device quality obtained using FT-luminescence spectroscopy, including insights into bandgap variations, defect and impurity effects, and relative recombination rates. We also describe our approach to extending the range of the FT-Raman spectrophotometer to cover the region from 11,500 to 3700 cm-1, enabling FT-luminescence measurements to be made from 1.42 to 0.46 eV, and our investigation of FT-PL microspectroscopy.

Plasma rockets are being considered for both Earth-orbit and interplanetary missions because their extremely high exhaust velocity and ability to modulate thrust allow very efficient use of propellant mass. In such rockets, a hydrogen or helium plasma is RF-heated and confined by axial magnetic fields produced by coils around the plasma chamber. HTS coils cooled by the propellant are desirable to increase the energy efficiency of the system. We describe a set of prototype high-temperature superconducting (HTS) coils that are being considered for the VASIMR ( Variable Specific Impulse Magnetoplasma Rocket) thruster proposed for testing on the Radiation Technology Demonstration (RTD) satellite. Since this satellite will be launched by the Space Shuttle, for safety reasons liquid helium will be used as propellant and coolant. The coils must be designed to operate in the space environment at field levels of 1 T. This generates a unique set of requirements. Details of the overall winding geometry and current density, as well as the challenging thermal control aspects associated with a compact, minimum weight design will be discussed.