Corrosion and scaling by steam in nuclear geothermal power plants (open access)

Corrosion and scaling by steam in nuclear geothermal power plants

None
Date: June 2, 1972
Creator: Krikorian, O.H.
Object Type: Report
System: The UNT Digital Library
Materials selection of surface coatings in an advanced size reduction facility. [For decommissioned stainless steel equipment] (open access)

Materials selection of surface coatings in an advanced size reduction facility. [For decommissioned stainless steel equipment]

A materials selection test program was conducted to characterize optimum interior surface coatings for an advanced size reduction facility. The equipment to be processed by this facility consists of stainless steel apparatus (e.g., glove boxes, piping, and tanks) used for the chemical recovery of plutonium. Test results showed that a primary requirement for a satisfactory coating is ease of decontamination. A closely related concern is the resistance of paint films to nitric acid - plutonium environments. A vinyl copolymer base paint was the only coating, of eight paints tested, with properties that permitted satisfactory decontamination of plutonium and also performed equal to or better than the other paints in the chemical resistance, radiation stability, and impact tests.
Date: June 2, 1980
Creator: Briggs, J. L. & Younger, A. F.
Object Type: Report
System: The UNT Digital Library
Experimental test accelerator: description and results of initial experiments (open access)

Experimental test accelerator: description and results of initial experiments

The ETA is a high current (10,000 Amp) linear induction accelerator that produces short (30 ns) pulses of electrons at 5 MeV twice per second or in bursts of 5 pulses separated by as little as one millisecond. At this time the machine has operated at 65% of its design current and 90% of the design voltage. This report contains a description of the accelerator and its diagnostics; the results of the initial year of operation; a comparison of design codes with experiments on beam transport; and a discussion of some of the special problems and their status.
Date: June 2, 1980
Creator: Fessenden, T.; Birx, D. & Briggs, R.
Object Type: Report
System: The UNT Digital Library
Interfacing the tandem mirror reactor to the sulfur-iodine process for hydrogen production (open access)

Interfacing the tandem mirror reactor to the sulfur-iodine process for hydrogen production

The blanket is linked to the H/sub 2/SO/sub 4/ vaporization units and SO/sub 3/ decomposition reactor with either sodium or helium. The engineering and safety problems associated with these choices are discussed. This H/sub 2/SO/sub 4/ step uses about 90% of the TMR heat and is best close-coupled to the nuclear island. The rest of the process we propose to be driven by steam and does not require close-coupling. The sodium loop coupling seems to be preferable at this time. We can operate with a blanket around 1200 K and the SO/sub 3/ decomposer around 1050 K. This configuration offers double-barrier protection between Li-Na and the SO/sub 3/ process gases. Heat pipes offer an attractive alternate to provide an additional barrier, added modularity for increased reliability, and tritium concentration and isolation operations with very little thermal penalty.
Date: June 2, 1980
Creator: Galloway, T.R.
Object Type: Article
System: The UNT Digital Library
Studies in tandem mirror theory. Paper IAEA-CN-38/F-4 (open access)

Studies in tandem mirror theory. Paper IAEA-CN-38/F-4

This paper discusses the formation, maintenance, and microstability of thermal barriers, which have been introduced as a means for improving tandem mirror reactor performance at reduced technological demands. It also describes calculations of tandem mirror central-cell ..beta.. limits due to MHD ballooning modes.
Date: June 2, 1980
Creator: Baldwin, D. E.; Cohen, R. H. & Cutler, T. A.
Object Type: Article
System: The UNT Digital Library
Growth of Second Phase Particles in a Copper--Beryllium Alloy. Final Technical Report (open access)

Growth of Second Phase Particles in a Copper--Beryllium Alloy. Final Technical Report

Growth of second phase particles from a solid solution of copper-beryllium was studied to determine this alloy's suitability for acoustic emission testing. Optical and Scanning Electron microscopes were used to study the microstructure. Micro and macro hardness tests were also performed. A hardness curve for aging at 550/sup 0/F was determined. Microscopic examination revealed the presence of large inclusions which make this alloy unsuitable for the acoustic tests envisioned.
Date: June 2, 1977
Creator: Bunch, R.; Wells, R. & Mukherjee, A. K.
Object Type: Report
System: The UNT Digital Library
Some comments on the Shiva spaceframe earthquake damage (open access)

Some comments on the Shiva spaceframe earthquake damage

On January 24, 1980, at 11:00 a.m., an earthquake, measuring 5.5 on the Richter scale, shook the Livermore Valley. There were three very pronounced shocks, the first at 5.5 followed by two, one at 5.2 and the other at 4.8, on the Richter scale. The Shiva spaceframe was shaken out of alignment. Shiva consists of two frames, a laser frame and a target frame. Components on each frame stayed within alignment with respect to each other, but the target frame moved with respect to the laser frame. Shearing of the seismic anchor bolts on the target frame was responsible for this misalignment. This was the third in a series of earthquakes for Shiva, the first occurring on June 20, 1977 at a magnitude of 4.7 on the Richter scale and an epicenter 2 miles away. The second quake was on August 6, 1979, with a magnitude of 5.9 and the epicenter 60 miles away. There was no damage or misalignment due to these first two earthquakes. The third however, severely tested the Shiva system and will be the subject of this report. Accelerometers were not in operation on the system so we do not know what the acceleration forces were. …
Date: June 2, 1980
Creator: Hurley, C.A.
Object Type: Report
System: The UNT Digital Library
China's Top-1000 Energy-Consuming Enterprises Program:Reducing Energy Consumption of the 1000 Largest Industrial Enterprises in China (open access)

China's Top-1000 Energy-Consuming Enterprises Program:Reducing Energy Consumption of the 1000 Largest Industrial Enterprises in China

In 2005, the Chinese government announced an ambitious goal of reducing energy consumption per unit of GDP by 20% between 2005 and 2010. One of the key initiatives for realizing this goal is the Top-1000 Energy-Consuming Enterprises program. The energy consumption of these 1000 enterprises accounted for 33% of national and 47% of industrial energy usage in 2004. Under the Top-1000 program, 2010 energy consumption targets were determined for each enterprise. The objective of this paper is to evaluate the program design and initial results, given limited information and data, in order to understand the possible implications of its success in terms of energy and carbon dioxide emissions reductions and to recommend future program modifications based on international experience with similar target-setting agreement programs. Even though the Top-1000 Program was designed and implemented rapidly, it appears that--depending upon the GDP growth rate--it could contribute to somewhere between approximately 10% and 25% of the savings required to support China's efforts to meet a 20% reduction in energy use per unit of GDP by 2010.
Date: June 2, 2008
Creator: Price, Lynn; Price, Lynn; Wang, Xuejun & Yun, Jiang
Object Type: Report
System: The UNT Digital Library
CHEMISTRY OF +1 IODINE IN ALKALINE SOLUTION (open access)

CHEMISTRY OF +1 IODINE IN ALKALINE SOLUTION

The iodine species formed either by adding hypochlorite to a basic iodide solution or by adding triiodide to sodium hydroxide, was identified as hypoiodite ion. The absorption spectrum of IO{sup -} was investigated in the wavelength range from 450 m{micro} to 280 m{micro}. The kinetics of the reaction I{sup -} + ClO{sup -} = IO{sup -} + Cl{sup -} was studied spectrophotometrically in alkaline solution. The forward rate law was found to be d(IO{sup -})/dt = k(I{sup -})(ClO{sup -})/OH{sup -}. At 25 C and an ionic strength of 1.00 M, k is 61 {+-} 3 sec{sup -1}. It was found spectrophotometrically that for certain ratios of the initial iodide to hydroxide concentrations, there was evidence of the presence of I{sub 3}{sup -}, I{sub 2}OH{sup -}, and I{sub 2}O{sup 2-} along with IO{sup -}. The equilibrium constants between IO{sup -} and these three species were evaluated by a graphical method. The formal potential of the cell: Pt:H{sub 2}:1 M NaOH : 1M NaOH, KI, NaIO : Au was found to be 1.297 v at 25 C. The equilibrium constant, K{sub 2} = (I{sub 3}{sup -})(OH{sup -}){sup 2}/(IO{sup -})(I{sup -}){sup 2}, of the reaction IO{sup -} + 2I{sup -} + H{sub 2}O …
Date: June 2, 1958
Creator: Chia, Yuan-tsan.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Ge Interface Engineering with Ozone-oxidation for Low Interface State Density (open access)

Ge Interface Engineering with Ozone-oxidation for Low Interface State Density

Passivation of Ge has been a critical issue for Ge MOS applications in future technology nodes. In this letter, we introduce ozone-oxidation to engineer Ge/insulator interface. Interface states (D{sub it}) values across the bandgap and close to conduction bandedge were extracted using conductance technique at low temperatures. D{sub it} dependency on growth conditions was studied. Minimum D{sub it} of 3 x 10{sup 11} cm{sup -2} V{sup -1} was demonstrated. Physical quality of the interface was investigated through Ge 3d spectra measurements. We found that the interface and D{sub it} is strongly affected by the distribution of oxidation states and quality of the suboxide.
Date: June 2, 2008
Creator: Kuzum, Duygu; Krishnamohan, T.; Pethe, Abhijit J.; Okyay, Ali K.; Oshima, Yasuhiro; Sun, Yun et al.
Object Type: Article
System: The UNT Digital Library
Opportunities for TeV Laser Acceleration (open access)

Opportunities for TeV Laser Acceleration

A set of ballpark parameters for laser, plasma, and accelerator technologies that define for electron energies reaching as high as TeV are identified. These ballpark parameters are carved out from the fundamental scaling laws that govern laser acceleration, theoretically suggested and experimentally explored over a wide range in the recent years. In the density regime on the order of 10{sup 16} cm{sup -3}, the appropriate laser technology, we find, matches well with that of a highly efficient high fluence LD driven Yb ceramic laser. Further, the collective acceleration technique applies to compactify the beam stoppage stage by adopting the beam-plasma wave deceleration, which contributes to significantly enhance the stopping power and energy recovery capability of the beam. Thus we find the confluence of the needed laser acceleration parameters dictated by these scaling laws and the emerging laser technology. This may herald a new technology in the ultrahigh energy frontier.
Date: June 2, 2008
Creator: Kando, M.; Kiriyama, H.; Koga, J. K.; Bulanov, S.; Chao, A. W.; Esirkepov, T. et al.
Object Type: Article
System: The UNT Digital Library
beta 1 integrin inhibition dramatically enhances radiotherapy efficacy in human breast cancer xenografts (open access)

beta 1 integrin inhibition dramatically enhances radiotherapy efficacy in human breast cancer xenografts

{beta}1 integrin signaling has been shown to mediate cellular resistance to apoptosis after exposure to ionizing radiation (IR). Other signaling molecules that increase resistance include Akt, which promotes cell survival downstream of {beta}1 integrin signaling. We showed previously that {beta}1 integrin inhibitory antibodies, AIIB2, enhance apoptosis and decrease growth in human breast cancer cells in 3 dimensional laminin-rich extracellular matrix (3D lrECM) cultures and in vivo. Here we asked whether AIIB2 could synergize with IR to modify Akt-mediated IR resistance. We used 3D lrECM cultures to test the optimal combination of AIIB2 with IR treatment of two breast cancer cell lines, MCF-7 and HMT3522-T4-2, as well as T4-2 myr-Akt breast cancer colonies or HMT3522-S-1, which form normal organotypic structures in 3D lrECM. Colonies were assayed for apoptosis and {beta}1 integrin/Akt signaling pathways were evaluated using western blot. In addition, mice bearing MCF-7 xenografts were used to validate the findings in 3D lrECM. We report that AIIB2 increased apoptosis optimally post-IR by down regulating Akt in breast cancer colonies in 3D lrECM. In vivo, addition of AIIB2 after IR significantly enhanced tumor growth inhibition and apoptosis compared to either treatment alone. Remarkably, the degree of tumor growth inhibition using AIIB2 plus …
Date: June 2, 2008
Creator: Park, Catherine C.; Park, Catherine C.; Zhang, Hui J.; Yao, Evelyn S.; Park, Chong J. & Bissell, Mina J.
Object Type: Article
System: The UNT Digital Library
Deprotection blue in extreme ultraviolet photoresists: influence of base loading and post-exposure bake temperture (open access)

Deprotection blue in extreme ultraviolet photoresists: influence of base loading and post-exposure bake temperture

The deprotection blur of Rohm and Haas XP 5435, XP 5271, and XP5496 extreme ultraviolet photoresists has been determined as their base weight percent is varied. They have also determined the deprotection blur of TOK EUVR P1123 photoresist as the post-exposure bake temperature is varied from 80 C to 120 C. In Rohm and Haas XP 5435 and XP5271 resists 7x and 3x (respective) increases in base weight percent reduce the size of successfully patterned 1:1 line-space features by 16 nm and 8 nm with corresponding reductions in deprotection blur of 7 nm and 4 nm. In XP 5496 a 7x increase in base weight percent reduces the size of successfully patterned 1:1 line-space features from 48 nm to 38 nm without changing deprotection blur. In TOK EUVR P1123 resist, a reduction in post-exposure bake temperature from 100 C to 80 C reduces deprotection blur from 21 nm to 10 nm and reduces patterned LER from 4.8 nm to 4.1 nm.
Date: June 2, 2008
Creator: Anderson, Christopher N. & Naulleau, Patrick P.
Object Type: Article
System: The UNT Digital Library
Modeling and Analysis of Ultra-Relativistic Heavy-Ion Collisions (open access)

Modeling and Analysis of Ultra-Relativistic Heavy-Ion Collisions

This document contains the final report for DOE grant DE-FG02-03ER41239: Modeling and Analysis of Ultra-Relativistic Heavy-Ion Collisions
Date: June 2, 2008
Creator: Bass, Steffen A.
Object Type: Text
System: The UNT Digital Library
Interpretation of long-offset transient electromagnetic data fromMount Merapi, Indonesia, using a three-dimensional optimizationapproach (open access)

Interpretation of long-offset transient electromagnetic data fromMount Merapi, Indonesia, using a three-dimensional optimizationapproach

In the years 1998, 2000, and 2001, long-offset transientelectromagnetic (LOTEM) surveys were carried out at the active volcanoMerapi in Central Java. The measurements investigated the conductivitystructure of the volcanic edifice. Our area of interest, which is belowthe summit and the upper flanks, was investigated using horizontal andvertical magnetic field time derivative data from seventransmitter-receiver setups. Because of topography and athree-dimensional (3-D) underground structure, a 3-D interpretation isused. The method optimizes few parameters of a 3-D model by a stableleast squares joint inversion of the data, providing sufficientresolution capability. Reasonable data fits are achieved with anonhorizontally layered model featuring a very conductive basement belowdepths of 1.5 km. While hydrothermal alteration is also considered, wetentatively explain the high conductivities by aqueous solutions withrelatively high salt contents. A large magma body or a small superficialreservoir below Merapi's central volcanic complex, as discussed by otherauthors, cannot be resolved by the LOTEM data.
Date: June 2, 2004
Creator: Commer, Michael; Helwig, Stefan L.; Hordt, Andreas & Tezkan, Bulent
Object Type: Article
System: The UNT Digital Library
Utility bill comprehension in the commercial and industrial sector: results of field research (open access)

Utility bill comprehension in the commercial and industrial sector: results of field research

This paper presents the results of interviews conducted with 44 business people in 10 states to examine the use of the utility bill as an information mechanism for providing businesses with the relationship between energy consumption and cost. Our results indicate that there are significant barriers to the use of the utility bill as an information tool for energy consumers. Furthermore, we found significant variations among respondents in the information desired from the bill, and differences in decision-making criteria for investments aimed at reducing energy consumption and for those aimed at other forms of waste minimization. These results call into question the applicability of standard market theories in the purchase of energy by most businesses.
Date: June 2, 2000
Creator: Payne, Christopher T.
Object Type: Article
System: The UNT Digital Library
Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam (open access)

Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam

A small set of final prototypes of the ATLAS Inner Detector silicon tracking system(Pixel Detector and SemiConductor Tracker), were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignmentof the silicon modules is of the order of 5 mm in their most precise coordinate.
Date: June 2, 2008
Creator: Ahmad, A.; Andreazza, A.; Atkinson, T.; Baines, J.; Barr, A. J.; Beccherle, R. et al.
Object Type: Article
System: The UNT Digital Library
Field-Analysis of Vacuum Free-Space LaserAcceleration from Rough-Surface and Absorbing Thin Boundaries (open access)

Field-Analysis of Vacuum Free-Space LaserAcceleration from Rough-Surface and Absorbing Thin Boundaries

This script presents a field-based analysis of laser acceleration of relativistic electrons in a free space that is bounded by a thin scattering or by a thin absorbing surface. The laser acceleration process is analyzed in terms of the inverse-radiation formalism and compared to the more familiar field path-integral analysis method. When the scattering boundary is modeled as a linear-index medium the predictions for laser-electron interactions from both field methods are found to agree. For the absorbing boundary both interaction pictures are also found to agree provided that the inverse radiation method is generalized to include absorption of energy from the boundary that is modeled as a linear ohmic-loss object.
Date: June 2, 2008
Creator: Plettner, Thomas & /Stanford U., Ginzton Lab.
Object Type: Article
System: The UNT Digital Library
Ion Beam Deposition of (NbTa)2O5/SiO2 Multilayers for High-Efficiency Dielectric Gratings for High Average Power Laser Systems Operating at 800 nm Central Wavelength (open access)

Ion Beam Deposition of (NbTa)2O5/SiO2 Multilayers for High-Efficiency Dielectric Gratings for High Average Power Laser Systems Operating at 800 nm Central Wavelength

The ion beam deposition of (NbTa)2O5 has been investigated for realizing high reflectance multilayer stacks of high damage threshold for applications in the engineering of dielectric gratings for use at 800 nm. Deposition conditions were optimized to yield fully oxidized films as determined from x-ray photoelectron spectroscopy (XPS). The film properties were also investigated using spectroscopic ellipsometry, and spectrophotometry to determine their refractive index and thickness respectively. Damage threshold testing was performed on single films using an amplified Ti:Sapphire laser producing a train of 170 ps pulses at a wavelength of 800 nm with an average energy of 100 mJ. The laser output was focused at the surface of the samples via a 0.5 m focal length lens to generate fluences ranging from 0 to 9 J/cm{sup 2}. At the optimum deposition conditions for highest optical quality and damage threshold, high reflector stacks of (NbTa){sub 2}O{sub 5}/SiO2 were fabricated. These stacks were employed to fabricate dielectric gratings with 1740 l/mm for use with 800 nm light. At an input angle of 8{sup o} from Littrow and a wavelength from 770 to 830 nm, >90% diffraction efficiency is achieved, with peak diffraction efficiency of >97%. The demonstration of dielectric gratings at …
Date: June 2, 2006
Creator: Menoni, C. S.; Patel, D.; Brizuela, F.; Rocca, J. J.; Nguyen, H. T. & Britten, J. A.
Object Type: Article
System: The UNT Digital Library
Relationship Between Atmospheric circulation and Snowpack in theWestern United States (open access)

Relationship Between Atmospheric circulation and Snowpack in theWestern United States

Snow anomalies in the western United States (U.S.) have beenwidely investigated by many researchers due to its impact on wateravailability. This study focuses on how anomalous atmospheric circulationaffects snowpack accumulation in the western U.S. using observations andoutput from the National Center for Atmospheric Research (NCAR) CommunityClimate Model version 3 (CCM3). Our results indicate that themid-latitude atmospheric circulation anomalies induced by the ElNino-Southern Oscillation (ENSO) tend to drive winter precipitationshifts, leading to an anomalous snowpack distribution in the western U.S.The warm phase of ENSO produces increased snowpack in the Southwest,while the cold phase of ENSO generates increased snowpack in theNorthwest. Temperature has a secondary impact on the anomalous snowpackdistribution during ENSO episodes. Additionally, the non-linearatmospheric dynamics-related Pacific-North American (PNA) pattern isfound to strongly affect snow anomalies in the western U.S. independentfrom ENSO. The positive phase of the PNA pattern produces coldertemperature and stronger precipitation due to the lower pressure in theregion, leading to an above normal snowpack. Conversely, the negativephase of the PNA pattern generates warmer temperature and weakerprecipitation resulting from the higher pressure, producing a below thannormal snowpack in the western U.S. In general, the NCAR-CCM3 reproducesthe observed processes. However, model biases are identified andreported. The information provided in this …
Date: June 2, 2004
Creator: Jin, Jiming; Miller, Norman L.; Sorooshian, Soroosh & Gao, Xiaogang
Object Type: Article
System: The UNT Digital Library
Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time (open access)

Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time

A simple, observationally-motivated model is presented for understanding how halo masses, galaxy stellar masses, and star formation rates are related, and how these relations evolve with time. The relation between halo mass and galaxy stellar mass is determined by matching the observed spatial abundance of galaxies to the expected spatial abundance of halos at multiple epochs--i.e. more massive galaxies are assigned to more massive halos at each epoch. This 'abundance matching' technique has been shown previously to reproduce the observed luminosity- and scale-dependence of galaxy clustering over a range of epochs. Halos at different epochs are connected by halo mass accretion histories estimated from N-body simulations. The halo-galaxy connection at fixed epochs in conjunction with the connection between halos across time provides a connection between observed galaxies across time. With approximations for the impact of merging and accretion on the growth of galaxies, one can then directly infer the star formation histories of galaxies as a function of stellar and halo mass. This model is tuned to match both the observed evolution of the stellar mass function and the normalization of the observed star formation rate--stellar mass relation to z {approx} 1. The data demands, for example, that the star …
Date: June 2, 2008
Creator: Conroy, Charlie & Wechsler, Risa H.
Object Type: Article
System: The UNT Digital Library
Measurements of B to {pi, eta, eta'} l nu Branching Fractions andDetermination of |Vub| with Semileptonically Tagged B Mesons (open access)

Measurements of B to {pi, eta, eta'} l nu Branching Fractions andDetermination of |Vub| with Semileptonically Tagged B Mesons

The authors report measurements of branching fractions for the decays B {yields} P{ell}{nu}{sub {ell}}, where P are the pseudoscalar charmless mesons {pi}{sup -}, {pi}{sup 0}, {eta} and {eta}{prime}, based on 348 fb{sup -1} of data collected with the BABAR detector, using B{sup 0} and B{sup +} mesons found in the recoil of a second B meson decaying as B {yields} D{sup (*)}{ell}{nu}{sub {ell}}. Assuming isospin symmetry, they combine pionic branching fractions to obtain {Beta}(B{sup 0} {yields} {pi}{sup -} {ell}{sup +} {nu}{sub {ell}}) = (1.54 {+-} 0.17{sub (stat)} {+-} 0.09{sub (syst)}) x 10{sup -4}; they find 3.2{sigma} evidence of the decay B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}} and measure its branching fraction to be (0.64 {+-} 0.20{sub (stat)} {+-} 0.3{sub (syst)}) x 10{sup -4}, and determine {Beta}(B{sup +} {yields} {eta}{prime}{ell}{sup +}{nu}{sub {ell}}) < 0.47 x 10{sup -4} to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a recent form factor calculation, they obtain the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}| = (4.0 {+-} 0.5{sub (stat)} {+-} 0.2{sub (syst){sub -0.5}{sup +0.7}(theory)}) x 10{sup -3}.
Date: June 2, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Object Type: Article
System: The UNT Digital Library
XPD Helicase Structures and Activities: Insights into the Cancer and Aging Phenotypes from XPD Mutations (open access)

XPD Helicase Structures and Activities: Insights into the Cancer and Aging Phenotypes from XPD Mutations

Mutations in XPD helicase, required for nucleotide excision repair (NER) as part of the transcription/repair complex TFIIH, cause three distinct phenotypes: cancer-prone xeroderma pigmentosum (XP), or aging disorders Cockayne syndrome (CS), and trichothiodystrophy (TTD). To clarify molecular differences underlying these diseases, we determined crystal structures of the XPD catalytic core from Sulfolobus acidocaldarius and measured mutant enzyme activities. Substrate-binding grooves separate adjacent Rad51/RecA-like helicase domains (HD1, HD2) and an arch formed by 4FeS and Arch domains. XP mutations map along the HD1 ATP-binding edge and HD2 DNA-binding channel and impair helicase activity essential for NER. XP/CS mutations both impair helicase activity and likely affect HD2 functional movement. TTD mutants lose or retain helicase activity but map to sites in all four domains expected to cause framework defects impacting TFIIH integrity. These results provide a foundation for understanding disease consequences of mutations in XPD and related 4Fe-4S helicases including FancJ.
Date: June 2, 2008
Creator: Tainer, John; Fan, Li; Fuss, Jill O.; Cheng, Quen J.; Arvai, Andrew S.; Hammel, Michal et al.
Object Type: Article
System: The UNT Digital Library
Probabilistic consequence model of accidenal or intentional chemical releases. (open access)

Probabilistic consequence model of accidenal or intentional chemical releases.

In this work, general methodologies for evaluating the impacts of large-scale toxic chemical releases are proposed. The potential numbers of injuries and fatalities, the numbers of hospital beds, and the geographical areas rendered unusable during and some time after the occurrence and passage of a toxic plume are estimated on a probabilistic basis. To arrive at these estimates, historical accidental release data, maximum stored volumes, and meteorological data were used as inputs into the SLAB accidental chemical release model. Toxic gas footprints from the model were overlaid onto detailed population and hospital distribution data for a given region to estimate potential impacts. Output results are in the form of a generic statistical distribution of injuries and fatalities associated with specific toxic chemicals and regions of the United States. In addition, indoor hazards were estimated, so the model can provide contingency plans for either shelter-in-place or evacuation when an accident occurs. The stochastic distributions of injuries and fatalities are being used in a U.S. Department of Homeland Security-sponsored decision support system as source terms for a Monte Carlo simulation that evaluates potential measures for mitigating terrorist threats. This information can also be used to support the formulation of evacuation plans and …
Date: June 2, 2008
Creator: Chang, Y.-S.; Samsa, M. E.; Folga, S. M. & Hartmann, H. M.
Object Type: Report
System: The UNT Digital Library