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Applications of X-ray absorption spectroscopy and low temperature XMCD to metalloproteins

Description: The author has used the extended X-ray absorption fine structure (EXAFS) and ultra-low temperature X-ray magnetic circular dichroism (XMCD) to study the environments of the metal sites in metalloproteins. EXAFS has been used to study the Zn site in spinach carbonic anhydrase. The EXAFS, in parallel with site directed mutagenesis studies, indicate that the active site Zn is in a cys-cys-his-H{sub 2}O environment, very different from the mammalian carbonic anhydrase active site. Nitrogenase, the primary enzyme in biological nitrogen fixation, contains two complex metal clusters of unique structure. EXAFS studies at the Fe and Mo K-edges of nitrogenase solutions and crystals yielded information about the various metal-metal distances in these two clusters. The author assigned 4 Fe and 3 Mo interactions >4 {angstrom}. Single crystal Mo K-edge EXAFS then found a very long Fe-Fe distance of {approximately}5.1 {angstrom}. These distances were then used to further refine the proposed crystallographic models to their highest accuracy yet. Studies were carried further by examining nitrogenas in oxidized and reduced forms--states for which there is no crystallographic information. Small structural changes were observed and an EXAFS model was put forth that attempts to deconvolute the EXAFS distances of the two metal clusters. Nitrogenase Apo I, a genetic mutant of nitrogenase which is though to contain only one of the two different metal clusters, was also examined using EXAFS. These studies showed results consistent with current models, yet the metal clusters were very disordered. Finally, ultra-low temperature methods were used to further the development of XMCD as a technique for studying biological systems. Experiments were performed on the copper in plastocyanin. Data was collected that definitively proves that the sample surface was at 0.55 {+-} 0.05 K. This result opens the door to further study of more complex biological metal clusters.
Date: January 1996
Creator: Christiansen, J. H.
Partner: UNT Libraries Government Documents Department

You Won`t Find These Leaks with a Blower Door: The Latest in "Leaking Electricity" in Homes

Description: Leaking electricity is the energy consumed by appliances when they are switched off or not performing their principal functions. Field measurements in Florida, California, and Japan show that leaking electricity represents 50 to 100 Watts in typical homes, corresponding to about 5 GW of total electricity demand in the United States. There are three strategies to reduce leaking electricity: eliminate leakage entirely, eliminate constant leakage and replace with intermittent charge plus storage, and improve efficiency of conversion. These options are constrained by the low value of energy savings-less than $5 per saved Watt. Some technical and lifestyle solutions are proposed. 13 refs., 1 fig., 2 tabs.
Date: August 1996
Creator: Rainer, L.; Greenberg, S. & Meier, A.
Partner: UNT Libraries Government Documents Department

Guidelines for sustainable building design: Recommendations from the Presidio of San Francisco energy efficiency design charrette

Description: In 1994, the Bay Chapter of the Association of Energy Engineers{reg_sign} organized a two-day design charrette for energy-efficient redevelopment of buildings by the National Park Services (NPS) at the Presidio of San Francisco. This event brought together engineers, researchers, architects, government officials, and students in a participatory environment to apply their experience to create guidelines for the sustainable redesign of Presidio buildings. The venue for the charrette was a representative barracks building located at the Main Post of the Presidio. Examination of this building allowed for the development of design recommendations, both for the building and for the remainder of the facilities. The charrette was organized into a committee structure consisting of: steering, measurement and monitoring, modeling, building envelope and historic preservation (architectural), HVAC and controls, lighting, and presentation. Prior to the charrette itself, the modeling and measurement/monitoring committees developed substantial baseline data for the other committees during the charrette. An integrated design approach was initiated through interaction between the committees during the charrette. Later, committee reports were cross-referenced to emphasize whole building design and systems integration.
Date: May 1996
Creator: Brown, K.; Sartor, D. & Greenberg, S.
Partner: UNT Libraries Government Documents Department

Energy effectiveness of duct sealing and insulation in two multifamily buildings

Description: Energy losses from forced air distribution systems have a significant impact on the energy efficiency of buildings. Little work has been done to quantify these losses in apartment buildings. In this paper the authors will discuss field measurements made on four forced air heating systems to evaluate the duct system energy losses to unconditioned basements. The apartments were heated by natural gas furnaces located in the basements. The systems had bare sheet metal ductwork exposed to the basement conditions. The pre-retrofit measurements were made on the systems after sealing large easily visible leaks. The post-retrofit measurements were made after wrapping the ducts in foil backed glass fiber insulation and additional leak sealing. Only the sections of duct exposed to the basement were retrofitted because only these sections were accessible. This study examines the potential energy savings for this type of limited retrofit. The energy losses were separated into leakage and conduction terms. Leakage measurements were made using register flowhood techniques. Conduction losses were estimated by measuring temperatures in the plenums and at the registers. Analysis of the measurements has shown typical reduction in leakage flow due to duct sealing of about 40%. The reduction in leakage translated into a reduction in energy consumption of about 10%.
Date: August 1996
Creator: Walker, I. S.; Modera, M. P.; Tuluca, A. & Graham, I.
Partner: UNT Libraries Government Documents Department

Decision making through use of interoperable simulation software

Description: Many building simulation computer programs, originally developed on mainframe computers for research purposes, can now run on the powerful workstation and personal computers that are available to most architectural and engineering firms. Major efforts have been underway during the last decade to compile these programs on personal computers and make them available to a wider range of building professionals. However, even with the addition of user-friendly front- and back-ends, their use is still limited to a small number of specialized consultants. Considering the tremendous benefits of informed decisions that these programs can support, it is critical to address and resolve the issues that are associated with their limited acceptance. In this paper, the authors report on their research and development efforts to better understand decision-making and develop computer tools that will facilitate the use of simulation software during the building design process. They present a brief analysis of decision-making and then describe how they try to address it in building design through the development of the Building Design Advisor (BDA). Moreover, the authors elaborate on the major issues that they have encountered, discuss lessons learned, and offer recommendations for short- and long-term developments in this area.
Date: March 1997
Creator: Papamichael, K.; La Porta, J. & Chauvet, H.
Partner: UNT Libraries Government Documents Department

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers

Description: A new type of charge restoration is described for use particularly in germanium gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need to AC couple detectors and the fact that very large energy depositions occur due to charged particles present in substantial fluxes, particularly in space. The circuit is described and experimental results are presented and discussed.
Date: July 1, 1997
Creator: Landis, D. A.; Madden, N. M. & Goulding, F. S.
Partner: UNT Libraries Government Documents Department

Electrochromic lithium nickel oxide thin film by pulsed laser deposition

Description: * Thin films of lithium nickel oxide were deposited by pulsed laser deposition (PLD) from targets of pressed LiNiO{sub 2} powder with layered structure. The composition, structure and surface air sensitivity of these films were analyzed using a variety of techniques, such as nuclear reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Optical properties were measured using a combination of variable angle spectroscopic ellipsometry and IP spectroradiometry. Crystalline structure, surface morphology and chemical composition of Li{sub x}Ni{sub 1-x}O thin films depend strongly on deposition oxygen pressure, temperature as well as substrate target distance. The films produced at temperatures lower than 600 degrees C spontaneously absorb CO{sub 2} and H{sub 2}O at their surface once they are exposed to the air. The films deposited at 600 degrees C proved to be stable in air over a long period. Even when deposited at room temperature the PLD films are denser and more stable than sputtered films. RBS determined that the best electrochromic films had the stoichiometric composition L{sub 0.5}Ni{sub 0.5}O when deposited at 60 mTorr O{sub 2} pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium and long cyclic life stability in a liquid electrolyte half cell. Electrochemical formatting which is used to develop electrochromism in other films and nickel oxide films is not needed for these stoichiometric films. The optical transmission range is almost 70% at 550 nm for 120 nm thick films.
Date: October 1996
Creator: Wen, S. J.; von Rottkay, K. & Rubin, M.
Partner: UNT Libraries Government Documents Department

Solar heat gain coefficient of complex fenestrations with a venetian blind for differing slat tilt angles

Description: Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.
Date: August 1996
Creator: Klems, J. H. & Warner, J. L.
Partner: UNT Libraries Government Documents Department

A comparison between calculated and measured SHGC for complex fenestration systems

Description: Calorimetric measurements of dynamic net heat flow through a complex fenestration system consisting of a buff venetian blind inside clear double glazing are used to derive the direction-dependent beam SHGC (solar heat gain coefficient) of the fenestration. The data are compared with calculations according to a proposed general method for deriving complex fenestration system SHGC`s from bidirectional layer optical properties and generic calorimetric properties. Previously published optical data for the same venetian blind and generic inward-flowing fraction measurements are used in the calculation. Satisfactory agreement is found between SHGC measurements and calculation. Significant dependence on incident angle was found in the measured SHGC`s. Profile angle was not found to be a useful variable in characterizing the system performance. Predicted SHGC was found to be inherently dependent on two angles, although only the incident angle variations were observable under test conditions.
Date: September 1995
Creator: Klems, J. H.; Warner, J. L. & Kelley, G. O.
Partner: UNT Libraries Government Documents Department

A field test of permeation grouting in heterogeneous soils using a new generation of barrier liquids

Description: A field demonstration of permeation grouting was conducted at a gravel quarry near Los Banos, California, with the purpose of demonstrating the feasibility of the concept. Two grouts were used: a form of colloidal silica that gels after the addition of a gelling agent, and a polysiloxane that polymerizes after the addition of a catalyst. Both create relatively impermeable barriers in response to the large increase in viscosity during gelation or polymerization, respectively. The grouts were successfully injected at a depth between 10 and 14ft. Subsequent exhumation of the injected gravels revealed that both grouts produced relatively uniform bulbs. Laboratory measurements of the grouted material retrieved from the field showed at least a four order of magnitude reduction in permeability over the ungrouted material.
Date: August 1995
Creator: Moridis, G. J.; Persoff, P.; Apps, J. A.; Myer, L.; Pruess, K. & Yen, P.
Partner: UNT Libraries Government Documents Department

The {alpha}-induced thick-target {gamma}-ray yield from light elements

Description: The {alpha}-induced thick-target {gamma}-ray yield from light elements has been measured in the energy range 5.6 MeV {le} E{sub {alpha}} {le} 10 MeV. The {gamma}-ray yield for > 2.1 MeV from thick targets of beryllium, boron nitride, sodium fluoride, magnesium, aluminum and silicon were measured using the {alpha}-particle beam from the Lawrence Berkeley Laboratories 88 in. cyclotron. The elemental yields from this experiment were used to construct the {alpha}-induced direct production {gamma}-ray spectrum from materials in the SNO detector, a large volume ultra-low background neutrino detector located in the Creighton mine near Sudbury, Canada. This background source was an order of magnitude lower than predicted by previous calculations. These measurements are in good agreement with theoretical calculations of this spectrum based on a statistical nuclear model of the reaction, with the gross high energy spectrum structure being reproduced to within a factor of two. Detailed comparison of experimental and theoretical excitation population distribution of several residual nuclei indicate the same level of agreement within experimental uncertainties.
Date: October 1994
Creator: Heaton, R. K.
Partner: UNT Libraries Government Documents Department

Current experiments in elementary particle physics

Description: This report contains summaries of 736 current and recent experiments in elementary particle physics (experiments that finished taking data before 1982 are excluded). Included are experiments at Brookhaven, CERN, CESR, DESY, Fermilab, Tokyo Institute of Nuclear Studies, Moscow Institute of Theoretical and Experimental Physics, Joint Institute for Nuclear Research (Dubna), KEK, LAMPF, Novosibirsk, PSI/SIN, Saclay, Serpukhov, SLAC, and TRIUMF, and also several underground experiments. Also given are instructions for searching online the computer database (maintained under the SLAC/SPIRES system) that contains the summaries. Properties of the fixed-target beams at most of the laboratories are summarized.
Date: September 1, 1989
Creator: Wohl, C. G.; Armstrong, F. E.; Trippe, T. G.; Yost, G. P. (Lawrence Berkeley Lab., CA (USA)); Oyanagi, Y. (Tsukuba Univ., Ibaraki (Japan)); Dodder, D. C. (Los Alamos National Lab., NM (USA)) et al.
Partner: UNT Libraries Government Documents Department

Amorphous silicon detectors in positron emission tomography

Description: The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.
Date: December 1, 1989
Creator: Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)) & Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))
Partner: UNT Libraries Government Documents Department

Intermediate-field transport of contaminants

Description: This report is about intermediate-field'' transport or the migration of contaminants from arrays of discrete waste packages or sources. In constructing nuclear waste repositories in rock, it may be necessary to place a waste package across a rock fracture, or a rock fracture may develop some time after waste packages have been emplaced. To predict the spatial and temporal distribution of contaminant species from a line of waste packages facing a rock fracture may be important, because such fractures may now be considered a preferential pathway for released radionuclides to re-enter the biosphere. In land disposal of hazardous wastes, individual barrels may contain especially toxic material whose dispersion special attention. We have published analytic solutions for the multidimensional advective transport of contaminants from arrays of waste packages and multiple areal sources into a planar fracture. The results show a near region in which the concentrations vary greatly in the direction transverse to ground-water flow, an intermediate region in which the array can be treated as an infinite plane source of dissolving species, and a far-field region in which the array can be treated as a plane source of finite extent. The array equations have been developed for both porous and fractured media. In this paper we summarize and compare the work with multiple areal sources facing a planar fracture and an array of point sources in porous media. 5 refs., 5 figs.
Date: June 1, 1989
Creator: Ahn, J. (Tokyo Univ. (Japan)); Kim, C. L. (Korea Advanced Energy Research Inst., Seoul (Republic of Korea)); Chambre, P. L.; Pigford, T. H. & Lee, W. W. L. (California Univ., Berkeley, CA (USA). Dept. of Nuclear Engineering Lawrence Berkeley Lab., CA (USA))
Partner: UNT Libraries Government Documents Department

Permeability and dispersivity of variable-aperture fracture systems

Description: A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs.
Date: January 1, 1990
Creator: Tsang, Y. W. & Tsang, C. F.
Partner: UNT Libraries Government Documents Department

Model estimates of the contributions of environmental tobacco smoke to volatile organic compound exposures in office buildings

Description: Volatile organic compounds (VOC) in office buildings originate from multiple sources, such as outdoor air, building materials, occupants, office supplies, and office equipment. Many of the VOC found in office buildings are also present in environmental tobacco smoke (ETS), e.g., benzene, toluene, formaldehyde. Measurements made to date in Office buildings have been interpreted by some to imply that the contributions to ETS to VOC exposures in office buildings are small. Four different ventilation-infiltration scenarios were modeled for a typical office building. The purpose of this investigation was to provide first-order estimate of the range of contributions of ETS to VOC contributions in office buildings under various ventilation conditions through the use of a mass-balance model and to evaluate the significance of such contributions relative to the VOC concentration measured in office buildings. 25 refs., 1 fig., 4 tabs.
Date: January 1, 1990
Creator: Daisey, J. M.; Gadgil, A. & Hodgson, A. T.
Partner: UNT Libraries Government Documents Department

FMG, RENUM, LINEL, ELLFMG, ELLP and DIMES: Chain of programs for calculating and analyzing fluid flow through two-dimensional fracture networks: Users manuals and listings

Description: The purpose of this report is to provide the user with sufficient information to run the programs FMG, RENUM, LINEL, and ELLFMG. A previous report explained the theory and the design of these programs, so that by using the two reports, a thorough understanding of the codes is possible. This report should familiarize the user with program options and modes of operation, input variables, input and output files. Information not strictly needed to run the programs, but useful in understanding their internal structure is provided in appendices. The appendices cover program variables and arrays, subroutine outlines, a short description of each subroutine, and finally listings of codes. The additional information on FMG, RENUM, LINEL, and ELLFMG is in Appendices A, C, E, G respectively, and the listings are in Appendices B, D, F, and H.
Date: September 30, 1989
Creator: Billaux, D.; Peterson, J.; Bodea, S. & Long, J.
Partner: UNT Libraries Government Documents Department

Seismic characterization of fracture properties

Description: The purpose of this paper is to show that there is a relationship, both empirical and theoretical, between the measured seismic response, the mechanical stiffness (also referred to as specific stiffness) of fractures and their hydraulic conductivity. Laboratory measurements of the mechanical stiffness, hydraulic conductivity and seismic properties of natural fractures are summarized. A theoretical model for the amplitude and group time delay for compressional and shear waves transmitted across a single fracture is presented. Predictions based on this model are compared with laboratory measurements. Finally, the results for a single fracture are extended to multiple parallel fractures. 13 refs., 6 figs.
Date: January 1, 1990
Creator: Myer, L. R.; Hopkins, D.; Cook, N. G. W. (Lawrence Berkeley Lab., CA (USA)) & Pyrak-Nolte, L. J. (Purdue Univ., Lafayette, IN (USA). Dept. of Earth and Atmospheric Sciences)
Partner: UNT Libraries Government Documents Department

Dynamic use of geoscience information to develop scientific understanding for a nuclear waste repository

Description: The development and safety evaluation of a nuclear waste geologic repository require a proper scientific understanding of the site response. Such scientific understanding depends on information from a number of geoscience disciplines, including geology, geophysics, geochemistry, geomechanics and hydrogeology. The information comes in four stages: (1) general regional survey data base, (2) surface-based testing, (3) exploratory shaft testing, and (4) repository construction and evaluation. A discussion is given on the dynamic use of the information through the different stages. We point out the need for abstracting, deriving and updating a quantitative spatial and process model (QSPM) to develop a scientific understanding of site responses as a crucial element in the dynamic procedure. 2 figs.
Date: January 1, 1990
Creator: Cook, N. G. W. & Tsang, C. F.
Partner: UNT Libraries Government Documents Department

In-situ fracture stiffness determination

Description: In-situ experiments to determine the hydrologic and mechanical characteristics of large naturally occurring fractures have been conducted at the NAGRA test site in Grimsel, Switzerland. In addition to seismic measurements across a fracture resulting from pressurization of the zone was also measured. The deformation is modeled in three different ways: as a mathematical crack employing linear elastic fracture mechanics; as a mathematical crack with an additional restraining stiffness between the faces of the crack, and as a row of coplanar two-dimensional cracks. 6 refs., 6 figs.
Date: January 1, 1990
Creator: Hesler, G. J. III (California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering); Zheng, Z. (Terra Tek, Inc., Salt Lake City, UT (USA)) & Myer, L. R. (Lawrence Berkeley Lab., CA (USA))
Partner: UNT Libraries Government Documents Department

Pressure dependence of the specific heat of heavy-fermion YbCu sub 4. 5

Description: The specific heat of a polycrystalline sample of YbCu{sub 4.5} has been measured between 0.3 and 20K at pressures to 8.2 kbar. Unlike cerium-based heavy-fermion compounds, an increase of C/T is observed with increasing pressure, with the linear term enhanced by about 16{percent} at 8.2 kbar. Above 7K, ({partial derivative}C/{partial derivative}P){sub T} is negative. The nuclear contribution observed at P {equals} 0 is increased by roughly a factor of two at 8.2 kbar. 7 refs., 3 figs.
Date: March 1, 1990
Creator: Amato, A.; Fisher, R. A.; Phillips, N. E. (Lawrence Berkeley Lab., CA (USA)); Jaccard, D. & Walker, E. (Geneva Univ. (Switzerland). Dept. de Physique de la Matiere Condensee)
Partner: UNT Libraries Government Documents Department

Modeling studies of the Ahuachapan geothermal field, El Salvador

Description: Modeling studies of Ahuachapan include analyses of interference test data, modeling of the fieldwide pressure decline and the development of a three-dimensional natural state model of the field. The main objective of this work is to obtain reasonable estimates for the transmissivity and storativity of the reservoir and to investigate fluid and heat flow patterns in the system. The analyses of the interference test data and the long term pressure decline data indicate that the average reservoir transmissivity is about 30 Dm and the storativity about 3.5 {times} 10{sup {minus}6} m/Pa. The natural state modeling supports an overall average transmissivity of 25--35 Dm and indicates that the system is recharged with 255{degree}C hot water at a rate of about 225 kg/s. The total thermal throughflow for the Ahuachapan system is estimated to be about 250 MW{sub t}. 10 refs., 11 figs., 3 tabs.
Date: January 1, 1989
Creator: Aunzo, Z.; Steingrimsson, B.; Bodvarsson, G. S. (Lawrence Berkeley Lab., CA (USA)); Escobar, C. & Quintanilla, A. (Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) (El Salvador))
Partner: UNT Libraries Government Documents Department