CH Packaging Program Guidance (open access)

CH Packaging Program Guidance

The purpose of this document is to provide the technical requirements for preparation for use, operation, inspection, and maintenance of a Transuranic Package Transporter Model II (TRUPACT-II), a HalfPACT shipping package, and directly related components. This document complies with the minimum requirements as specified in the TRUPACT-II Safety Analysis Report for Packaging (SARP), HalfPACT SARP, and U.S. Nuclear Regulatory Commission (NRC) Certificates of Compliance (C of C) 9218 and 9279, respectively. In the event of a conflict between this document and the SARP or C of C, the C of C shall govern. The C of Cs state: "each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application." They further state: "each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application." Chapter 9.0 of the SARP charges the U.S. Department of Energy (DOE) or the Waste Isolation Pilot Plant (WIPP) management and operating (M&O) contractor with assuring packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with Title 10 …
Date: December 13, 2007
Creator: None, None
Object Type: Report
System: The UNT Digital Library
Optimization Strategies for the Vulnerability Analysis of the Electric Power Grid (open access)

Optimization Strategies for the Vulnerability Analysis of the Electric Power Grid

Identifying small groups of lines, whose removal would cause a severe blackout, is critical for the secure operation of the electric power grid. We show how power grid vulnerability analysis can be studied as a mixed integer nonlinear programming (MINLP) problem. Our analysis reveals a special structure in the formulation that can be exploited to avoid nonlinearity and approximate the original problem as a pure combinatorial problem. The key new observation behind our analysis is the correspondence between the Jacobian matrix (a representation of the feasibility boundary of the equations that describe the flow of power in the network) and the Laplacian matrix in spectral graph theory (a representation of the graph of the power grid). The reduced combinatorial problem is known as the network inhibition problem, for which we present a mixed integer linear programming formulation. Our experiments on benchmark power grids show that the reduced combinatorial model provides an accurate approximation, to enable vulnerability analyses of real-sized problems with more than 10,000 power lines.
Date: November 13, 2007
Creator: Pinar, A.; Meza, J.; Donde, V. & Lesieutre, B.
Object Type: Article
System: The UNT Digital Library
MHD Induced Neutral Beam Ion Loss from NSTX Plasmas (open access)

MHD Induced Neutral Beam Ion Loss from NSTX Plasmas

Bursts of ~60 kHz activity on Mirnov coils occur frequently in NSTX plasmas and these are accompanied by bursts of neutral beam ion loss over a range in pitch angles. These losses have been measured with a scintillator type loss probe imaged with a high speed (>10,000 frames/s) video camera, giving the evolution of the energy and pitch angle distributions of the lost neutral beam ions over the course of the events. The instability occurs below the TAE frequency in NSTX (~100 kHz) in high beta plasmas and may be a beta driven Alfvén acoustic (BAAE) mode.
Date: December 13, 2007
Creator: D.S. Darrow, E.D. Fredrickson, N.N. Gorelenkov, A.L. Roquemore, and K. Shinohara
Object Type: Article
System: The UNT Digital Library
Overview of the Alcator C-MOD Research Program (open access)

Overview of the Alcator C-MOD Research Program

Recent research on the high-field, high-density diverted Alcator C-MOD tokamak has focussed on the plasma physics and plasma engineering required for ITER and for attractive fusion reactors. Experimental campaigns over the past two years have focused on understanding the physical mechanisms that affect the plasma performance realized with all-molybdenum walls versus walls with low-Z coatings. RF sheath rectification along flux tubes that intersect the RF antenna is found to be a major cause of localized boron erosion and impurity generation. Initial lower-hybrid current drive (LHCD) experiments (PLH < 900 kW) have demonstrated fully noninductive current drive at Ιρ ~ 1.0 MA with good efficiency, Ιdrive = 0.4PLH/neoR (MA,MW,1020m−3,m). Disruption mitigation via massive gas-jet impurity puffing has proven successful at high plasma pressure, indicating this technique has promise for implementation on ITER. Pressure gradients in the near SOL of Ohmic L-mode plasmas are observed to scale consistently as Ι 2(over)ρ, and show a significant dependence on X-point topology. Modeling of H-mode edge fueling indicates high self-screening to neutrals in the pedestal and scrape-off layer (SOL), and reproduces experimental density pedestal response to changes in neutral source. Detailed measurements of the temperature and density profiles in the near sol and fast framing …
Date: November 13, 2007
Creator: S. Scott, A. Bader, M. Bakhtiari, N. Basse, W. Beck, T. Biewer, S. Bernabei, P. Bonoli, et al.
Object Type: Article
System: The UNT Digital Library
Effects of Hydroelectric Dam Operations on the Restoration Potential of Snake River Fall Chinook Salmon (Oncorhynchus tshawytscha) Spawning Habitat Final Report, October 2005 - September 2007. (open access)

Effects of Hydroelectric Dam Operations on the Restoration Potential of Snake River Fall Chinook Salmon (Oncorhynchus tshawytscha) Spawning Habitat Final Report, October 2005 - September 2007.

This report describes research conducted by the Pacific Northwest National Laboratory for the Bonneville Power Administration (BPA) as part of the Fish and Wildlife Program directed by the Northwest Power and Conservation Council. The study evaluated the restoration potential of Snake River fall Chinook salmon spawning habitat within the impounded lower Snake River. The objective of the research was to determine if hydroelectric dam operations could be modified, within existing system constraints (e.g., minimum to normal pool levels; without partial removal of a dam structure), to increase the amount of available fall Chinook salmon spawning habitat in the lower Snake River. Empirical and modeled physical habitat data were used to compare potential fall Chinook salmon spawning habitat in the Snake River, under current and modified dam operations, with the analogous physical characteristics of an existing fall Chinook salmon spawning area in the Columbia River. The two Snake River study areas included the Ice Harbor Dam tailrace downstream to the Highway 12 bridge and the Lower Granite Dam tailrace downstream approximately 12 river kilometers. These areas represent tailwater habitat (i.e., riverine segments extending from a dam downstream to the backwater influence from the next dam downstream). We used a reference site, …
Date: November 13, 2007
Creator: Hanrahan, Timothy P.; Richmond, Marshall C. & Arntzen, Evan V.
Object Type: Report
System: The UNT Digital Library
Cometary X-ray emission: theoretical cross sections following charge exchange by multiply charged ions of astrophysical interest (open access)

Cometary X-ray emission: theoretical cross sections following charge exchange by multiply charged ions of astrophysical interest

The CTMC method is used to calculate emission cross sections following charge exchange collisions involving highly charged ions of astrophysical interest and typical cometary targets. Comparison is made to experimental data obtained on the EBIT machine at Lawrence Livermore National Laboratory (LLNL) for O{sup 8+} projectiles impinging on different targets at a collision energy of 10 eV/amu. The theoretical cross sections are used together with ion abundances measured by the Advanced Composition Explorer as well as those obtained by a fitting procedure using laboratory emission cross sections in order to reproduce the x-ray spectrum of comet C/LINEAR S4 measured on July 14th 2001.
Date: February 13, 2007
Creator: Otranto, S; Olson, R E & Beiersdorfer, P
Object Type: Article
System: The UNT Digital Library
The Hydrophobic Effect Drives the Recognition of Hydrocarbons by an Anionic Metal-Ligand Cluster (open access)

The Hydrophobic Effect Drives the Recognition of Hydrocarbons by an Anionic Metal-Ligand Cluster

None
Date: July 13, 2007
Creator: Biros, Shannon; Bergman, Robert & Raymond, Kenneth
Object Type: Article
System: The UNT Digital Library
The Independent Technical Analysis Process (open access)

The Independent Technical Analysis Process

The Bonneville Power Administration (BPA) contracted with the Pacific Northwest National Laboratory (PNNL) to provide technical analytical support for system-wide fish passage information (BPA Project No. 2006-010-00). The goal of this project was to produce rigorous technical analysis products using independent analysts and anonymous peer reviewers. In the past, regional parties have interacted with a single entity, the Fish Passage Center to access the data, analyses, and coordination related to fish passage. This project provided an independent technical source for non-routine fish passage analyses while allowing routine support functions to be performed by other well-qualified entities.
Date: April 13, 2007
Creator: Duberstein, Corey A.; Ham, Kenneth D.; Dauble, Dennis D. & Johnson, Gary E.
Object Type: Report
System: The UNT Digital Library
Developing and Extending a Cyberinfrastructure Model (open access)

Developing and Extending a Cyberinfrastructure Model

Increasingly, research and education institutions are realizing the strategic value and challenge of deploying and supporting institutional cyberinfrastructure (CI). Cyberinfrastructure is composed of high performance computing systems, massive storage systems, visualization systems, and advanced networks to interconnect the components within and across institutions and research communities. CI also includes the professionals with expertise in scientific application and algorithm development and parallel systems operation. Unlike ?regular? IT infrastructure, the manner in which the components are configured and skills to do so are highly specific and specialized. Planning and coordinating these assets is a fundamental step toward enhancing an institution?s research competitiveness and return on personnel, technology, and facilities investments. Coordinated deployment of CI assets has implications across the institution. Consider the VC for Research whose new faculty in the Life Sciences are now asking for simulation systems rather than wet labs, or the Provost who lost another faculty candidate to a peer institution that offered computational support for research, or the VC for Administration who has seen a spike in power and cooling demands from many of the labs and office spaces being converted to house systems. These are just some of the issues that research institutions are wrestling with as …
Date: November 13, 2007
Creator: Alvarez, Rosio
Object Type: Article
System: The UNT Digital Library
Progress with Tevatron Electron Lenses (open access)

Progress with Tevatron Electron Lenses

None
Date: September 13, 2007
Creator: Kamerdzhiev, V.; Alexahin, Y.; Kuznetsov, G. F.; Shiltsev, V. D. & Zhang, X.
Object Type: Article
System: The UNT Digital Library
New Equalizers for Antiproton Stochastic Cooling at Fermilab (open access)

New Equalizers for Antiproton Stochastic Cooling at Fermilab

In the continuous effort to improve antiproton stacking rate, a new type of equalizers has been developed and installed in antiproton accumulator. The R&amp;D of these new equalizers is described in this paper. Equalizers are used in Fermilab antiproton stochastic cooling to compensate frequency response of the cooling system. Usually both amplitude and phase compensations are needed. However in most cases it is difficult to achieve a satisfactory compensation for both because of their interdependence. To make it more difficult is that in some cases large compensations (10 to 20 db of amplitude compensation or more than 100 degree of phase compensation) are needed near the low or high ends of a frequency band. Recently a new compensation scheme of equalizers is proposed for Fermilab antiproton accumulator. This scheme originated from the requirement to maximize the system performance resulting in a request for the phase of the cooling system transfer function to be extremely flat. For this kind of phase correction, a new type of equalizers has been developed.
Date: September 13, 2007
Creator: Lebedev, V. A.; Pasquinelli, R. J. & Sun, D.
Object Type: Article
System: The UNT Digital Library
Exp6-polar thermodynamics of dense supercritical water (open access)

Exp6-polar thermodynamics of dense supercritical water

We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, isotherms and sound speeds, and are also quite good for the self-diffusion constant and relative dielectric constant. We expect the present approach to be also useful for other small polar molecules and their mixtures.
Date: December 13, 2007
Creator: Bastea, S & Fried, L E
Object Type: Article
System: The UNT Digital Library
Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition (open access)

Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition

Plutonium and its alloys exhibit complex phase diagrams that imply anomalous lattice dynamics near phase stability boundaries. Specifically, the TA [111] phonon branch in Ga-stabilized {delta}-Pu at room temperature shows a pronounced soft mode at the zone boundary, which suggests a possible connection to the martensitic transformation from the fcc {delta}-phase to the monoclinic {alpha}{prime}-phase at low temperatures. This work is a study of the lattice dynamics of this system by x-ray thermal diffuse scattering. The results reveal little temperature dependence of the phonon frequencies, thus indicating that kinetic phonon softening is not responsible for this phase transition.
Date: September 13, 2007
Creator: Xu, R; Wong, J; Zshack, P; Hong, H & Chiang, T
Object Type: Article
System: The UNT Digital Library
Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation (open access)

Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation

We argue that a primary focus on energy efficiency may not be sufficient to slow (and ultimately reverse) the growth in total energy consumption and carbon emissions. Instead, policy makers need to return to an earlier emphasis on&quot;conservation,&quot; with energy efficiency seen as a means rather than an end in itself. We briefly review the concept of&quot;intensive&quot; versus&quot;extensive&quot; variables (i.e., energy efficiency versus energy consumption), and why attention to both consumption and efficiency is essential for effective policy in a carbon- and oil-constrained world with increasingly brittle energy markets. To start, energy indicators and policy evaluation metrics need to reflect energy consumption as well as efficiency. We introduce the concept of&quot;progressive efficiency,&quot; with the expected or required level of efficiency varying as a function of house size, appliance capacity, or more generally, the scale of energy services. We propose introducing progressive efficiency criteria first in consumer information programs (including appliance labeling categories) and then in voluntary rating and recognition programs such as ENERGY STAR. As acceptance grows, the concept could be extended to utility rebates, tax incentives, and ultimately to mandatory codes and standards. For these and other programs, incorporating criteria for consumption as well as efficiency offers a path …
Date: August 13, 2007
Creator: Diamond, Rick; Harris, Jeff; Diamond, Rick; Iyer, Maithili; Payne, Christopher; Blumstein, Carl et al.
Object Type: Article
System: The UNT Digital Library
Radiological Survey Results for Areas A1 North, A5A, A6, and B2 at the Molycorp Washington Remediation Project, Washington, Pennsylvania (open access)

Radiological Survey Results for Areas A1 North, A5A, A6, and B2 at the Molycorp Washington Remediation Project, Washington, Pennsylvania

Perform radiological surveys of the Molycorp Washington Remediation Project (MWRP) facility in Washington, Pennsylvania
Date: March 13, 2007
Creator: Adams, W. C.
Object Type: Report
System: The UNT Digital Library
Soil Sampling Plan in Support of the Human Health and Ecological Risk Assessment for the Operation of the Explosives Waste Treatment Facilitiy at Site 300 of the Lawrence Livermore National Laboratory (open access)

Soil Sampling Plan in Support of the Human Health and Ecological Risk Assessment for the Operation of the Explosives Waste Treatment Facilitiy at Site 300 of the Lawrence Livermore National Laboratory

LLNL proposes to obtain soil samples from the following areas: (1) Four areas downwind of the Explosives Waste Treatment Facility (EWTF) Burn Units (i.e., Thermal Treatment Unit and Burn Pan); (2) One area upwind of the Burn Units and Detonation Pad; (3) Two areas downwind of the EWTF Detonation Pad; and (4) Three areas unaffected (representing ambient conditions) by EWTF operations approximately 7000-8000 feet upwind of the facility. The purpose of the sampling in areas 1, 2, and 3 is to detect if operations cause increases in concentrations of materials downwind of the Burn Units or downwind of the Detonation Pad. The purpose of the sampling in area 4 is to determine if previously developed background screening levels can be applied to EWTF operations. A 20 foot diameter circle will define each sample area. Soil samples will be obtained from four random locations inside each 20 foot circle. The samples will be obtained immediately below the surface, free of any organic matter (e.g., roots) and other surface and subsurface material (e.g., rocks) that is not conducive to analysis. The random identification of four discrete sample locations in each circle will allow the variability between sample locations and areas, if present, …
Date: December 13, 2007
Creator: Terusaki, S
Object Type: Report
System: The UNT Digital Library
Performance Demonstration Program Plan for Analysis of Simulated Headspace Gases (open access)

Performance Demonstration Program Plan for Analysis of Simulated Headspace Gases

The Performance Demonstration Program (PDP) for headspace gases distributes blind audit samples in a gas matrix for analysis of volatile organic compounds (VOCs). Participating measurement facilities (i.e., fixed laboratories, mobile analysis systems, and on-line analytical systems) are located across the United States. Each sample distribution is termed a PDP cycle. These evaluation cycles provide an objective measure of the reliability of measurements performed for transuranic (TRU) waste characterization. The primary documents governing the conduct of the PDP are the Quality Assurance Program Document (QAPD) (DOE/CBFO-94-1012) and the Waste Isolation Pilot Plant (WIPP) Waste Analysis Plan (WAP) contained in the Hazardous Waste Facility Permit (NM4890139088-TSDF) issued by the New Mexico Environment Department (NMED). The WAP requires participation in the PDP; the PDP must comply with the QAPD and the WAP. This plan implements the general requirements of the QAPD and the applicable requirements of the WAP for the Headspace Gas (HSG) PDP. Participating measurement facilities analyze blind audit samples of simulated TRU waste package headspace gases according to the criteria set by this PDP Plan. Blind audit samples (hereafter referred to as PDP samples) are used as an independent means to assess each measurement facility’s compliance with the WAP quality assurance …
Date: November 13, 2007
Creator: Office, Carlsbad Field
Object Type: Report
System: The UNT Digital Library
The silicon microstrip sensors of the ATLAS semiconductor tracker (open access)

The silicon microstrip sensors of the ATLAS semiconductor tracker

This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The sensors are now successfully assembled within the detecting modules of the SCT, and the SCT tracker is completed and integrated within the ATLAS Inner Detector. Hamamatsu Photonics Ltd. supplied 92.2percent of the 15,392 installed sensors, with the remainder supplied by CiS.
Date: April 13, 2007
Creator: Collaboration, ATLAS SCT & Spieler, Helmuth G.
Object Type: Article
System: The UNT Digital Library
Toward Fast Computation of Dense Image Correspondence on the GPU (open access)

Toward Fast Computation of Dense Image Correspondence on the GPU

Large-scale video processing systems are needed to support human analysis of massive collections of image streams. Video, from both current small-format and future large-format camera systems, constitutes the single largest data source of the near future, dwarfing the output of all other data sources combined. A critical component to further advances in the processing and analysis of such video streams is the ability to register successive video frames into a common coordinate system at the pixel level. This capability enables further downstream processing, such as background/mover segmentation, 3D model extraction, and compression. We present here our recent work on computing these correspondences. We employ coarse-to-fine hierarchical approach, matching pixels from the domain of a source image to the domain of a target image at successively higher resolutions. Our diamond-style image hierarchy, with total pixel counts increasing by only a factor of two at each level, improves the prediction quality as we advance from level to level, and reduces potential grid artifacts in the results. We demonstrate the quality our approach on real aerial city imagery. We find that registration accuracy is generally on the order of one quarter of a pixel. We also benchmark the fundamental processing kernels on the …
Date: August 13, 2007
Creator: Duchaineau, M; Cohen, J & Vaidya, S
Object Type: Article
System: The UNT Digital Library
Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains (open access)

Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains

Climate, vegetation cover, and management create fine-scaleheterogeneity in unirrigated agricultural regions, with important but notwell-quantified consequences for spatial and temporal variations insurface CO2, water, and heat fluxes. We measured eddy covariance fluxesin seven agricultural fields--comprising winter wheat, pasture, andsorghum--in the U.S. Southern Great Plains (SGP) during the 2001-2003growing seasons. Land-cover was the dominant source of variation insurface fluxes, with 50-100 percent differences between fields planted inwinter-spring versus fields planted in summer. Interannual variation wasdriven mainly by precipitation, which varied more than two-fold betweenyears. Peak aboveground biomass and growing-season net ecosystem exchange(NEE) of CO2 increased in rough proportion to precipitation. Based on apartitioning of gross fluxes with a regression model, ecosystemrespiration increased linearly with gross primary production, but with anoffset that increased near the time of seed production. Because theregression model was designed for well-watered periods, it successfullyretrieved NEE and ecosystem parameters during the peak growing season,and identified periods of moisture limitation during the summer. Insummary, the effects of crop type, land management, and water limitationon carbon, water, and energy fluxes were large. Capturing the controllingfactors in landscape scale models will be necessary to estimate theecological feedbacks to climate and other environmental impactsassociated with changing human needs for agricultural production of …
Date: June 13, 2007
Creator: Fischer, Marc L.; Billesbach, David P.; Berry, Joseph A.; Riley,William J. & Torn, Margaret S.
Object Type: Article
System: The UNT Digital Library
CHARACTERIZATION OF A HIGH CURRENT INDUCTION ACCELERATOR ELECTRON BEAM VIA OPTICAL TRANSITION RADIATION FROM DIELECTRIC FOILS (open access)

CHARACTERIZATION OF A HIGH CURRENT INDUCTION ACCELERATOR ELECTRON BEAM VIA OPTICAL TRANSITION RADIATION FROM DIELECTRIC FOILS

Traditionally, thin metal foils are employed for optical transition radiation (OTR) beam diagnostics but the possibility of shorting accelerator insulating surfaces and modifying accelerating fields are concerns. The successful utilization of dielectric foils in place of metal ones could alleviate these issues but necessitates more understanding of the OTR data for inferring desired beam parameters because of the dielectric's finite permittivity. Additionally, the temperature dependence of the relevant foil parameters due to beam heating should be accounted for. Here, we present and discuss sample synthetic diagnostic results of Kapton OTR spot-size measurements from the Flash X-Ray (FXR) accelerator which studies these and sightline effects. These simulations show that in some cases, the observed spot-sizes and radii are noticeably larger than the beam radii.
Date: June 13, 2007
Creator: Tang, V; Brown, C & Houck, T
Object Type: Article
System: The UNT Digital Library
Soft X-ray Mirrors for the Linac Coherent Light Source (open access)

Soft X-ray Mirrors for the Linac Coherent Light Source

The Linac Coherent Light Source (LCLS) is a 0.15-1.5 nm wavelength free-electron laser (FEL) being constructed at the Stanford Linear Accelerator Center (SLAC) by a multi-institution consortium, including Lawrence Livermore National Laboratory (LLNL). One of LLNL's responsibilities involves the design and construction of two grazing-incidence mirror systems whose primary intent is to reduce radiation levels in the experimental halls by separating the FEL beam from unwanted high-energy photons. This paper discusses one of these systems, the Soft X-ray Offset Mirror System (SOMS) that will operate in the wavelength range 0.62-1.5 nm (0.827-2.00 keV). The unusual properties of the FEL beam translate to stringent specifications in terms of stability, material choice and mirror properties. It also precludes using approaches previously developed for synchrotron light sources. This situation has led us to a unique mirror design, consisting of a reflective boron carbide layer deposited on a silicon substrate. In the first part of this paper, we discuss the basic system requirements for the SOMS and motivate the need for these novel reflective elements. In the second part of this paper, we discuss the development work we have performed, including simulation and experimental verification of the boron carbide coating properties, and the expected …
Date: August 13, 2007
Creator: Pivovaroff, M. J.; Bionta, R. M.; Mccarville, T. J.; Soufli, R. & Stefan, P. M.
Object Type: Article
System: The UNT Digital Library
Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems (open access)

Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems

In many regions, three dimensional characterization of the groundwater regime is limited by coarse well spacing or borehole lithologic logs of low quality. However, regulatory requirements for drinking water or site remediation may require collection of extensive chemical and water quality data from existing wells. Similarly, for wells installed in the distant past, lithologic logs may not be available, but the wells can be sampled for chemical and isotopic constituents. In these situations, a thorough analysis of trends in chemical and isotopic constituents can be a key component in characterizing the regional groundwater system. On a basin or subbasin scale, especially in areas of intensive groundwater management where artificial recharge is important, introduction of an extrinsic tracer can provide a robust picture of groundwater flow. Dissolved gases are particularly good tracers since a large volume of water can be tagged, there are no real or perceived health risks associated with the tracer, and a very large dynamic range allows detection of a small amount of tagged water in well discharge. Recent applications of the application of extrinsic tracers, used in concert with intrinsic chemical and isotopic tracers, demonstrate the power of chemical analyses in interpreting regional subsurface flow regimes.
Date: September 13, 2007
Creator: Moran, J E; Singleton, M J; Carle, S F & Esser, B K
Object Type: Article
System: The UNT Digital Library
Micropatterning of Gold Substrates Based on Poly(Propylene Sulfide-Bl-Ethylene Glycol), (Pps-Peg) Background Passivation and the Molecular-Assembly Patterning by Lift-Off (Mapl) Technique (open access)

Micropatterning of Gold Substrates Based on Poly(Propylene Sulfide-Bl-Ethylene Glycol), (Pps-Peg) Background Passivation and the Molecular-Assembly Patterning by Lift-Off (Mapl) Technique

Poly(propylene sulfide-bl-ethylene glycol) (PPS-PEG) is an amphiphilic block copolymer that spontaneously adsorbs onto gold from solution. This results in the formation of a stable polymeric layer that renders the surface protein resistant when an appropriate architecture is chosen. The established molecular assembly patterning by lift-off (MAPL) technique can convert a prestructured resist film into a pattern of biointeractive chemistry and a noninteractive background. Employing the MAPL technique, we produced a micron-scale PPS-PEG pattern on a gold substrate, and then characterized the patterned structure with Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Atomic Force Microscopy (AFM). Subsequent exposure of the PPS-PEG/gold pattern to protein adsorption (full human serum) was monitored in situ; SPR-imaging shows a selective adsorption of proteins on gold, but not on PPS-PEG areas. Analysis shows a reduction of serum adsorption up to 93% on the PPS-PEG areas as compared to gold, in good agreement with previous analysis on homogeneously adsorbed PPS-PEG on gold. MAPL patterning of PPS-PEG block copolymers fast, versatile and reproducible, and allows for subsequent use of biosensor-based surface analysis methods.
Date: November 13, 2007
Creator: Feller, L.; Bearinger, J. P.; Wu, L.; Hubbell, J. A.; Textor, M. & Tosatti, S.
Object Type: Article
System: The UNT Digital Library