Molecular dynamics (MD) simulations were carried out on the DNA oligonucleotide GGGAACAACTAG:CTAGTTGTTCCC in its native form and with guanine in the central G19:C6 base pair replaced by 8-oxoguanine (8oxoG). A box of explicit water molecules was used for solvation and Na+ counterions were added to neutralize the system. The direction and magnitude of global bending were assessed by a technique used previously to analyze simulations of DNA containing a thymine dimer. The presence of 8oxoG did not greatly affect the magnitude of DNA bending; however, bending into the major groove was significantly more probable when 8oxoG replaced G19. Crystal structures of glycosylases bound to damaged-DNA substrates consistently show a sharp bend into the major groove at the damage site. We conclude that changes in bending dynamics that assist the formation of this kink are a part of the mechanism by which glycosylases of the base excision repair pathway recognize the presence of 8oxoG in DNA.

The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.

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Electrical resistivity may contribute to progress inunderstanding geothermal systems by imaging the geometry, bounds andcontrolling structures in existing production, and thereby perhapssuggesting new areas for field expansion. To these ends, a dense grid ofmagnetotelluric (MT) stations plus a single line of contiguous bipolearray profiling has been acquired over the east flank of the Cosogeothermal system. Acquiring good quality MT data in producing geothermalsystems is a challenge due to production related electromagnetic (EM)noise and, in the case of Coso, due to proximity of a regional DCintertie power transmission line. To achieve good results, a remotereference completely outside the influence of the dominant source of EMnoise must be established. Experimental results so far indicate thatemplacing a reference site in Amargosa Valley, NV, 65 miles from the DCintertie, isstill insufficient for noise cancellation much of the time.Even though the DC line EM fields are planar at this distance, theyremain coherent with the nonplanar fields in the Coso area hence remotereferencing produces incorrect responses. We have successfully unwrappedand applied MT times series from the permanent observatory at Parkfield,CA, and these appear adequate to suppress the interference of thecultural EM noise. The efficacy of this observatory is confirmed bycomparison to stations taken using an ultra-distant …

Density-functional formalism is applied to study the ground state properties of {gamma}-U-Zr and {gamma}-U-Mo solid solutions. Calculated heats of formation are compared with CALPHAD assessments. We discuss how the heat of formation in both alloys correlates with the charge transfer between the alloy components. The decomposition curves for {gamma}-based U-Zr and U-Mo solid solutions are derived from Ising-type Monte Carlo simulations. We explore the idea of stabilization of the {delta}-UZr{sub 2} compound against the {alpha}-Zr (hcp) structure due to increase of Zr d-band occupancy by the addition of U to Zr. We discuss how the specific behavior of the electronic density of states in the vicinity of the Fermi level promotes the stabilization of the U{sub 2}Mo compound. The mechanism of possible Am redistribution in the U-Zr and U-Mo fuels is also discussed.

Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength …

This note is an update to the muon calculations presented in CN-221 and takes into account: (1) a more complete muon production and transport model, including an estimate of wide angle production based on experimental data, (2) additional earth shielding that will be added on top and both sides of the 2/3 tunnel areas, and (3) a detailed analysis of the earth profile as it pertains to shielding in the direction of the SLAC site boundary. The highest annual dose at the SLAC boundary is found to be 13 mrem/year (4000 hours of operation at 50 kW), and this occurs at a horizontal angle of 0 degrees and a vertical angle of 3.6 degrees relative to the incident beam direction. Although the shielding criteria is 10 mrem/year at the site boundary, the radiation transport model becomes somewhat conservative at large distances from the shield, which should bring the 13 mrem/year number actually well below the criteria. This point is also about 28 feet above the roadway. Extension of this line may strike the ground in the Christmas tree farm beyond the SLAC boundary but there will be additional attenuation due to distance. We do not recommend that any additional shielding …

The primary objective of this research is to conduct advanced reservoir characterization and modeling studies in the Antelope Shale reservoir. Characterization studies will be used to determine the technical feasibility of implementing a CO2 enhanced oil recovery project in the Antelope Shale in Buena Vista Hills Field. The Buena Vista Hills pilot CO2 project will demonstrate the economic viability and widespread applicability of CO2 flooding in fractured siliceous shale reservoirs of the San Joaquin Valley. The research consists of four primary work processes: Reservoir Matrix and Fluid Characterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO2 Pilot Flood and Evaluation. Work done in these areas is subdivided into two phases or budget periods. The first phase of the project will focus on the application of a variety of advanced reservoir characterization techniques to determine the production characteristics of the Antelope Shale reservoir. Reservoir models based on the results of the characterization work will be used to evaluate how the reservoir will respond to secondary recovery and EOR processes. The second phase of the project will include the implementation and evaluation of an advanced enhanced oil recovery (EOR) pilot in the United Anticline (West Dome) of the Buena Vista Hills Field.

The primary objective of this research is to conduct advanced reservoir characterization and modeling studies in the Antelope Shale reservoir. Characterization studies will be used to determine the technical feasibility of implementing a CO{sub 2} enhanced oil recovery project in the Antelope Shale in Buena Vista Hills Field. The Buena Vista Hills pilot CO{sub 2} project will demonstrate the economic viability and widespread applicability of CO{sub 2} flooding in fractured siliceous shale reservoirs of the San Joaquin Valley. The research consists of four primary work processes: Reservoir Matrix and Fluid Characterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO{sub 2} Pilot Flood and Evaluation. Work done in these areas is subdivided into two phases or budget periods. The first phase of the project focused on the application of a variety of advanced reservoir characterization techniques to determine the production characteristics of the Antelope Shale reservoir. Reservoir models based on the results of the characterization work will be used to evaluate how the reservoir will respond to secondary recovery and EOR processes. The second phase of the project will include the implementation and evaluation of an advanced enhanced oil recovery (EOR) pilot in the United Anticline (West Dome) of the Buena …

A high level rf system, including a power amplifier and cavity, has been designed and built for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity protons. Low intensity polarized protons and heavy ions, to the 1.5 GeV level. A total accelerating voltage of up to 90 kV will be provided by two cavities, each having two gaps. The internally cross coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate beam intensities up to 0.75 {times} 10{sup 13} protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two parallel cells. The amplifier is a grounded cathode configuration driven by a remotely located solid-state amplifier. It has been tested in the laboratory at full gap voltage with satisfactory results. 5 refs., 2 figs., 1 tab.

The Control System for the Advanced Light Source uses in-house designed IndustryPack (IP) I/O Modules in compact PCI (cPCI) chassis to control instrumentation. Each module consists of digital I/O ports and 16-bit analog I/O interfaced to instrumentation via a cPCI rear I/O card. During the past few years of installed operation, several factors have prompted investigation into the design of a new IP I/O Module. The ADC channels have significant offset drift over periods of days of initial installed operation. An in-situ calibration procedure was developed to address this problem, but it lacks speed and is inconvenient to perform. Digital I/O port limitations have led to increasing amounts of wasted I/O. Fast orbit feedback requires faster ADC sampling and better filtering than the current IP module offers. This paper discusses the issues related to the current IP I/O Module and the design of a new Double-size IP I/O Module.

Examination of corrosion coupons by transmission electron microscopy after their exposure in the Idaho Advanced Test Reactor (ATR) has broadened the Zircaloy-4 precipitate-amorphization database and validated a new kinetic model for previously unavailable values of temperature and fast-neutron flux. The model describes the amorphization of Zr(Fe,Cr){sub 2} intermetallic precipitates in zirconium alloys as a dynamic competition between radiation damage and thermal annealing that leaves some iron atoms available for flux-assisted diffusion to the zirconium matrix. It predicts the width of the amorphous zone as a function of neutron flux (E>1 MeV), temperature, and time. In its simplest form, the model treats the crystalline/amorphous and precipitate/matrix interfaces as parallel planes, and its accuracy decreases for small precipitates and high fluence as the amorphous-zone width approaches precipitate dimensions. The simplest form of the model also considers diffusion to be rate-determining. This is an accurate approximation for steady-state conditions or slow changes in flux and temperature, but inappropriate for the analysis of faster transients. The paper addresses several difficulties inherent in measuring amorphous-zone width, and utilizes the expanded database to evaluate the improvements in predictive accuracy available through both conversion of the model to spherical coordinates and extension of its time dependency.

One of the major factors restricting reactor power levels is the incidence of ruptured slugs. The primary purpose in studying ruptures is to determine how reactor operating variables affect rupture rates. With this knowledge reactor operating conditions may be adjusted or controlled in the manner that will optimize reactor production. In addition, knowledge of rupture rate relationships are useful in fuel element development and in overall economic studies of existing and proposed reactors and reactor processes. This report is a compendium of various types of rupture information largely developed during the past eighteen months. Plant rupture experience for CY-1957 is reviewed; rupture rate correlations with reactor variables for solid natural uranium material are presented; a comparison between solid and cored natural uranium material rupture rates is made; the basis for current discharging practice of rupture-prone metal lots is discussed. 11 figs., 2 tabs.

As the Barrel Tile Calorimeter is constructed, the support saddles and the modules will be subjected to different forces, stresses, and deflections than when completely assembled. The purpose of this analysis is to examine the forces, stresses, and deflections acting on the support saddles and modules at various stages of assembly. The nominal weight of a barrel module is 20 tons. CERN Document number ATL-LB-EA-0001 'Summary of the Structural Analysis of the Barrel Support Saddles' describes in detail the structural analysis of the saddles and the completed barrel assembly. These calculations followed Eurocode 3. This paper examined several load cases which occur during the assembly of the Barrel. The following are the main conclusions: (1) The assembly is not stable until 18 modules are in place, and only then can the support cradle be removed; (2) The forces between modules are nominal and are far less that the forces in the completed cylinder with 64 modules in place and the cryostat load applied; (3) All of the stresses in the connections between modules are within acceptable limits; and (4) The interface between the cryostat supports and the cryostat move approximately 1.0 mm in the X and Y directions when the …

Angular distributions in SIGMA /sup +/ decay are analyzed for informatlon on SIGMA spin and parity conservation in SIGMA production. No evidence for a SIGMA spin > 1/2 or parity nonconservation in SIGMA prodiction is found. (auth)

The filtrate stream from the precipitation--filtration step of the Button Line process must be recycled to recovery operations to reclaim residual plutonium. Present practice is to transfer the filtrates to Recuplex, concentrate by a factor of 6 to 10, and blend into the feed stream for solvent extraction purification. Limited tankage is available for solution storage. Interruption of Recuplex operations necessitates termination of operations in the precipitation-filtration steps and other Button Line areas. Filtrates can be recycled to one of the parent solvent extraction plants for recovery. However, excessive handling operations are encountered by this processing method. This document describes the anion exchange flow sheets and equipment for processing the filtrate stream without dependence upon other recovery operations.

In the dewatering project, two different approaches are taken. One approach involves displacing the water on the surface of coal by a hydrophobic substance that can be readily recovered and recycled. This novel concept, referred to as the Hydrophobic Dewatering (HD) process, is based on improved understanding of the surface chemistry of dewatering. The other approach is to use disposable dewatering substances in mechanical dewatering. The objectives of the proposed work are (1) to test the HD process on a variety of coals from the Appalachian coal fields, and (2) to identify suitable dewatering reagents that would enable mechanical dewatering to reduce the moisture to the levels satisfactory to electrical utilities and other coal users. The objective of the spiral separation project is to use computer modeling to develop better, more efficient spiral designs for coal cleaning. The fully-developed model will predict spiral performance based on variations in spiral profile, flow rate, and pitch. Specific goals are to: (1) design spirals capable of making separations at a specific gravity of 1.5, and (2) broaden the size range at which spirals make effective separations.

The design of the NLC Beam Delivery System requires a firmer understanding of the effects of collimators on short, intense bunches than is presently available. We describe an experiment to directly measure these effects through use of a dedicated apparatus located at the 1.19 GeV point in the SLAC Linac. The apparatus consists of an outer vacuum vessel and an interchangeable insertion containing up to 5 distinct collimator apertures. The insertion is capable of remote-controlled translation, allowing the collimator apertures to be misaligned relative to the electron beam without changing the incoming beam orbit; the wakefield deflection is then measured by observing the change in the outgoing orbit on 32 beam position monitors. The parameters of the apertures have been selected to allow confirmation of the scaling laws for collimator wakefields, and to strongly enhance either the geometric or resistive wall contribution of each aperture. Details of the apparatus design, the aperture parameters, and the experimental program are discussed.

As part of the U.S. National Spent Nuclear Fuel Program, aluminide fuels (UAl{sub x}) are being tested under conditions that might exist in the proposed repository at Yucca Mountain, Nevada. Intermittent drip tests at 90 C were completed for up to 183 days on partially declad, unirradiated, low-enriched UAl{sub x} samples. Through 183 days of exposure to modified water from the J-13 well at 90 C, the fuel coupon remained in good mechanical condition. Only a tarnishing of the surface was observed and no spalled products were found in the fuel holder. The mechanism for alteration is consistent with that observed from dry oxidation experiments on UAl{sub x} (for the initial corrosion) and humid UO{sub 2} oxidation (for the subsequent paragenesis). Specifically, solid-state conversion of UAl{sub x} into UO{sub 2} and oxidized Al is followed by further oxidation, dissolution of the uranium, and reprecipitation as uranyl oxyhydroxides. The release rate of uranium varied from 0.23 to 2.9 mg/m{sup 2}/day (avg. = 0.97 mg U/m{sup 2}/day) depending on the specimen and test interval, but was similar in magnitude to that observed in earlier flow-through and drip tests with irradiated UAl{sub x} and UO{sub 2}. Most (mean=87%) of the released uranium sorbed …

This project is for the design of a wind turbine that can generate most or all of the net energy required for homes and small businesses in moderately windy areas. The purpose is to expand the current market for residential wind generators by providing cost effective power in a lower wind regime than current technology has made available, as well as reduce noise and improve reliability and safety. Robert W. Preus’ experience designing and/or maintaining residential wind generators of many configurations helped identify the need for an improved experience of safety for the consumer. Current small wind products have unreliable or no method of stopping the wind generator in fault or high wind conditions. Consumers and their neighbors do not want to hear their wind generators. In addition, with current technology, only sites with unusually high wind speeds provide payback times that are acceptable for the on-grid user. Abundant Renewable Energy’s (ARE) basic original concept for the ARE660 was a combination of a stall controlled variable speed small wind generator and automatic fail safe furling for shutdown. The stall control for a small wind generator is not novel, but has not been developed for a variable speed application with a …

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Astronomical applications of adaptive optics at Lawrence Livermore National Laboratory (LLNL) has a history that extends from 1984. The program started with the Lick Observatory Adaptive Optics system and has progressed through the years to lever-larger telescopes: Keck, and now the proposed CELT (California Extremely Large Telescope) 30m telescope. LLNL AO continues to be at the forefront of AO development and science.

This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated …