A high-throughput contact-hole resolution metric for photoresists: Full-process sensitivity study (open access)

A high-throughput contact-hole resolution metric for photoresists: Full-process sensitivity study

None
Date: January 22, 2008
Creator: Anderson, Christopher & Jones, Juanita
System: The UNT Digital Library
Constructing QCD one-loop amplitudes (open access)

Constructing QCD one-loop amplitudes

In the context of constructing one-loop amplitudes using a unitarity bootstrap approach we discuss a general systematic procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted after examining the behavior of the cut integrand as the unconstrained parameters of a specifically chosen parameterization of the cut loop momentum approach infinity. Measurements of new physics at the forthcoming experimental program at CERN's Large Hadron Collider (LHC) will require a precise understanding of processes at next-to-leading order (NLO). This places increased demands for the computation of new one-loop amplitudes. This in turn has spurred recent developments towards improved calculational techniques. Direct calculations using Feynman diagrams are in general inefficient. Developments of more efficient techniques have usually centered around unitarity techniques [1], where tree amplitudes are effectively 'glued' together to form loops. The most straightforward application of this method, in which the cut loop momentum is in D = 4, allows for the computation of 'cut-constructible' terms only, i.e. (poly)logarithmic containing terms and any related constants. QCD amplitudes contain, in addition to such terms, rational pieces which cannot be derived using such cuts. These 'missing' rational parts can be extracted using cut loop …
Date: February 22, 2008
Creator: Forde, Darren
System: The UNT Digital Library
BIOASSAY VESSEL FAILURE ANALYSIS (open access)

BIOASSAY VESSEL FAILURE ANALYSIS

Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.
Date: September 22, 2008
Creator: Vormelker, P
System: The UNT Digital Library
Enantioselective Intramolecular Hydroarylation of Alkenes via Directed C-H Bond Activation (open access)

Enantioselective Intramolecular Hydroarylation of Alkenes via Directed C-H Bond Activation

Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe){sub 2}]{sub 2} and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1,2-disubstituted as well as trisubstituted alkenes were achieved with enantioselectivities >90% ee for each substrate class. Cyclization of substrates with Z-alkene isomers proceeded much more efficiently than substrates with E-alkene isomers. This further enabled the highly stereoselective intramolecular alkylation of certain substrates containing Z/E-alkene mixtures via a Rh-catalyzed alkene isomerization with preferential cyclization of the Z-isomer.
Date: May 22, 2008
Creator: Harada, Hitoshi; Thalji, Reema; Bergman, Robert & Ellman, Jonathan
System: The UNT Digital Library
NUCLEAR POWERED CO2 CAPTURE FROM THE ATMOSPHERE (open access)

NUCLEAR POWERED CO2 CAPTURE FROM THE ATMOSPHERE

A process for capturing CO{sub 2} from the atmosphere was recently proposed. This process uses a closed cycle of sodium and calcium hydroxide, carbonate, and oxide transformations to capture dilute CO{sub 2} from the atmosphere and to generate a concentrated stream of CO{sub 2} that is amenable to sequestration or subsequent chemical transformations. In one of the process steps, a fossil-fueled lime kiln is needed, which reduces the net CO{sub 2} capture of the process. It is proposed to replace the fossil-fueled lime kiln with a modified kiln heated by a high-temperature nuclear reactor. This will have the effect of eliminating the use of fossil fuels for the process and increasing the net CO{sub 2} capture. Although the process is suitable to support sequestration, the use of a nuclear power source for the process provides additional capabilities, and the captured CO{sub 2} may be combined with nuclear-produced hydrogen to produce liquid fuels via Fischer-Tropsch synthesis or other technologies. Conceivably, such plants would be carbon-neutral, and could be placed virtually anywhere without being tied to fossil fuel sources or geological sequestration sites.
Date: September 22, 2008
Creator: Sherman, S
System: The UNT Digital Library
Towards a Real-time Transient Classification Engine (open access)

Towards a Real-time Transient Classification Engine

Temporal sampling does more than add another axis to the vector of observables. Instead, under the recognition that how objects change (and move) in time speaks directly to the physics underlying astronomical phenomena, next-generation wide-field synoptic surveys are poised to revolutionize our understanding of just about anything that goes bump in the night (which is just about everything at some level). Still, even the most ambitious surveys will require targeted spectroscopic follow-up to fill in the physical details of newly discovered transients. We are now building a new system intended to ingest and classify transient phenomena in near real-time from high-throughput imaging data streams. Described herein, the Transient Classification Project at Berkeley will be making use of classification techniques operating on"features" extracted from time series and contextual (static) information. We also highlight the need for a community adoption of a standard representation of astronomical time series data (i.e.,"VOTimeseries").
Date: February 22, 2008
Creator: Nugent, Peter E.; Bloom, Josh; Starr, Dan; Butler, Nat; Nugent, Peter; Rischard, M. et al.
System: The UNT Digital Library
Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge (open access)

Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge

Here we examine Fe speciation within Fe-encrusted biofilms formed during 2-month seafloor incubations of sulfide mineral assemblages at the Main Endeavor Segment of the Juan de Fuca Ridge. The biofilms were distributed heterogeneously across the surface of the incubated sulfide and composed primarily of particles with a twisted stalk morphology resembling those produced by some aerobic Fe-oxidizing microorganisms. Our objectives were to determine the form of biofilm-associated Fe, and identify the sulfide minerals associated with microbial growth. We used micro-focused synchrotron-radiation X-ray fluorescence mapping (mu XRF), X-ray absorption spectroscopy (mu EXAFS), and X-ray diffraction (mu XRD) in conjunction with focused ion beam (FIB) sectioning, and highresolution transmission electron microscopy (HRTEM). The chemical and mineralogical composition of an Fe-encrusted biofilm was queried at different spatial scales, and the spatial relationship between primary sulfide and secondary oxyhydroxide minerals was resolved. The Fe-encrusted biofilms formed preferentially at pyrrhotite-rich (Fe1-xS, 0<_ x<_ 0.2) regions of the incubated chimney sulfide. At the nanometer spatial scale, particles within the biofilm exhibiting lattice fringing and diffraction patterns consistent with 2-line ferrihydrite were identified infrequently. At the micron spatial scale, Fe mu EXAFS spectroscopy and mu XRD measurements indicate that the dominant form of biofilm Fe is a …
Date: May 22, 2008
Creator: Toner, Brandy M.; Santelli, Cara M.; Marcus, Matthew A.; Wirth, Richard; Chan, Clara S.; McCollom, Thomas et al.
System: The UNT Digital Library
Aryl Bridged 1-Hydroxypyridin-2-one: Sensitizer Ligands for Eu(III) (open access)

Aryl Bridged 1-Hydroxypyridin-2-one: Sensitizer Ligands for Eu(III)

The synthesis, crystal structure, solution stability and photophysical properties of an aryl group bridging two 1-hydroxypyridin-2-one units complexed to Eu(III) are reported. The results show that this backbone unit increases the rigidity of the ensuing complex, and also the conjugation of the ligand. As a result of the latter, the singlet absorption energy is decreased, along with the energy of the lowest excited triplet state. The resulting efficiency of sensitization for the Eu(III) ion is influenced by these phenomena, yielding an overall quantum yield of 6.2% in aqueous solution. The kinetic parameters arising from the luminescence data reveal an enhanced non-radiative decay rate for this compound when compared to previously reported aliphatic bridges.
Date: February 22, 2008
Creator: D'Aleo, Anthony; Xu, Jide; Moore, Evan G.; Jocher, Christoph J. & Raymond, Kenneth N.
System: The UNT Digital Library
Stencil Computation Optimization and Auto-tuning on State-of-the-Art Multicore Architectures (open access)

Stencil Computation Optimization and Auto-tuning on State-of-the-Art Multicore Architectures

Understanding the most efficient design and utilization of emerging multicore systems is one of the most challenging questions faced by the mainstream and scientific computing industries in several decades. Our work explores multicore stencil (nearest-neighbor) computations -- a class of algorithms at the heart of many structured grid codes, including PDE solvers. We develop a number of effective optimization strategies, and build an auto-tuning environment that searches over our optimizations and their parameters to minimize runtime, while maximizing performance portability. To evaluate the effectiveness of these strategies we explore the broadest set of multicore architectures in the current HPC literature, including the Intel Clovertown, AMD Barcelona, Sun Victoria Falls, IBM QS22 PowerXCell 8i, and NVIDIA GTX280. Overall, our auto-tuning optimization methodology results in the fastest multicore stencil performance to date. Finally, we present several key insights into the architectural trade-offs of emerging multicore designs and their implications on scientific algorithm development.
Date: August 22, 2008
Creator: Datta, Kaushik; Murphy, Mark; Volkov, Vasily; Williams, Samuel; Carter, Jonathan; Oliker, Leonid et al.
System: The UNT Digital Library
Distinguishing Aerosol Impacts on Climate Over the Past Century (open access)

Distinguishing Aerosol Impacts on Climate Over the Past Century

Aerosol direct (DE), indirect (IE), and black carbon-snow albedo (BAE) effects on climate between 1890 and 1995 are compared using equilibrium aerosol-climate simulations in the Goddard Institute for Space Studies General Circulation Model coupled to a mixed layer ocean. Pairs of control(1890)-perturbation(1995) with successive aerosol effects allow isolation of each effect. The experiments are conducted both with and without concurrent changes in greenhouse gases (GHG's). A new scheme allowing dependence of snow albedo on black carbon snow concentration is introduced. The fixed GHG experiments global surface air temperature (SAT) changed -0.2, -1.0 and +0.2 C from the DE, IE, and BAE. Ice and snow cover increased 1.0% from the IE and decreased 0.3% from the BAE. These changes were a factor of 4 larger in the Arctic. Global cloud cover increased by 0.5% from the IE. Net aerosol cooling effects are about half as large as the GHG warming, and their combined climate effects are smaller than the sum of their individual effects. Increasing GHG's did not affect the IE impact on cloud cover, however they decreased aerosol effects on SAT by 20% and on snow/ice cover by 50%; they also obscure the BAE on snow/ice cover. Arctic snow, ice, …
Date: August 22, 2008
Creator: Koch, Dorothy; Menon, Surabi; Del Genio, Anthony; Ruedy, Reto; Alienov, Igor & Schmidt, Gavin A.
System: The UNT Digital Library
Next Generation Safeguards Initiative Workshop on Enhanced Recruiting for International Safeguards (open access)

Next Generation Safeguards Initiative Workshop on Enhanced Recruiting for International Safeguards

In 2007, the National Nuclear Security Administration's Office of Nonproliferation and International Security (NA-24) completed a yearlong review of the challenges facing the international safeguards system today and over the next 25 years. The study found that without new investment in international safeguards, the U.S. safeguards technology base, and our ability to support International Atomic Energy Agency (IAEA) safeguards, will continue to erode and soon may be at risk. To reverse this trend, the then U.S. Secretary of Energy, Samuel Bodman, announced at the 2007 IAEA General Conference that the Department of Energy (DOE) would launch the Next Generation Safeguards Initiative (NGSI). He stated 'IAEA safeguards must be robust and capable of addressing proliferation threats. Full confidence in IAEA safeguards is essential for nuclear power to grow safely and securely. To this end, the U.S. Department of Energy will seek to ensure that modern technology, the best scientific expertise, and adequate resources are available to keep pace with expanding IAEA responsibilities.' To meet this goal, the NGSI objectives include the recruitment of international safeguards experts to work at the U.S. national laboratories and to serve at the IAEA's headquarters. Part of the latter effort will involve enhancing our existing efforts …
Date: October 22, 2008
Creator: Pepper, S.; Rosenthal, M.; Fishbone, L.; Occhiogrosso, D.; Carroll, C.; Dreicer, M. et al.
System: The UNT Digital Library
Paradigm Changes in High Temperature Plasma Physics Research and Implications for ITER (open access)

Paradigm Changes in High Temperature Plasma Physics Research and Implications for ITER

Significant high temperature plasma research in both the magnetic and inertial confinement regimes led to the official launching of the International Thermonuclear Experimental Reactor (ITER) project which is aimed at challenging controlled fusion power for human kind. In particular, such an endeavor originated from the fruitful research outcomes from the world wide magnetic confinement devices (primarily based on the Tokamak approach) mainly in advanced countries (US, EU, and Japan). In recent years, all new steady state capable Tokamak devices are operated and/or constructed in Asian countries and incidentally, the majority of the ITER consortium consists of Asian countries. This provides an opportunity to revisit the unresolved essential physics issues and/or extend the understanding of the transient physics to the required steady state operation so that ITER can benefit from these efforts. The core physics of a magnetically confined hot plasma has two essential components; plasma stability and cross-field energy transport physics. Complete understanding of these two areas is critical for the successful operation of ITER and perhaps, Demo reactor construction. In order to have stable high beta plasmas with a sufficiently long confinement time, the physics of an abrupt disruption and sudden deterioration of the energy transport must be understood …
Date: February 22, 2008
Creator: Park, Hyeon K.
System: The UNT Digital Library
Hadronic resonance production in d + Au collisions at sqrt s NN = 200 GeV at RHIC (open access)

Hadronic resonance production in d + Au collisions at sqrt s NN = 200 GeV at RHIC

We present the first measurements of the {rho}(770){sup 0}, K*(892), {Delta}(1232){sup ++}, {Sigma}(1385), and {Lambda}(1520) resonances in d+Au collisions at {radical}s{sub NN} = 200 GeV, reconstructed via their hadronic decay channels using the STAR detector at RHIC. The masses and widths of these resonances are studied as a function of transverse momentum (p{sub T}). We observe that the resonance spectra follow a generalized scaling law with the transverse mass (m{sub T}). The <p{sub T}> of resonances in minimum bias collisions is compared to the <p{sub T}> of {pi}, K, and {bar p}. The {rho}{sup 0}/{pi}{sup -}, K*/K{sup -}, {Delta}{sup ++}/p, {Sigma}(1385)/{Lambda}, and {Lambda}(1520)/{Lambda} ratios in d + Au collisions are compared to the measurements in minimum bias p + p interactions, where we observe that both measurements are comparable. The nuclear modification factors (R{sub dAu}) of the {rho}{sup 0}, K*, and {Sigma}* scale with the number of binary collisions (N{sub bin}) for p{sub T} > 1.2 GeV/c.
Date: August 22, 2008
Creator: STAR Collaboration
System: The UNT Digital Library
Plans for Warm Dense Matter Experiments and Ife Target Experiments on Ndcx-Ii (open access)

Plans for Warm Dense Matter Experiments and Ife Target Experiments on Ndcx-Ii

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is currently developing design concepts for NDCX-II, the second phase of the Neutralized Drift Compression Experiment, which will use ion beams to explore Warm Dense Matter (WDM) and Inertial Fusion Energy (IFE) target hydrodynamics. The ion induction accelerator will consist of a new short pulse injector and induction cells from the decommissioned Advanced Test Accelerator (ATA) at Lawrence Livermore National Laboratory (LLNL). To fit within an existing building and to meet the energy and temporal requirements of various target experiments, an aggressive beam compression and acceleration schedule is planned. WDM physics and ion-driven direct drive hydrodynamics will initially be explored with 30 nC of lithium ions in experiments involving ion deposition, ablation, acceleration and stability of planar targets. Other ion sources which may deliver higher charge per bunch will be explored. A test stand has been built at Lawrence Berkeley National Laboratory (LBNL) to test refurbished ATA induction cells and pulsed power hardware for voltage holding and ability to produce various compression and acceleration waveforms. Another test stand is being used to develop and characterize lithium-doped aluminosilicate ion sources. The first experiments will include heating metallic targets to 10,000 K and …
Date: September 22, 2008
Creator: Waldron, W. L.; Barnard, J. J.; Bieniosek, F. M.; Friedman, A.; Henestroza, E.; Leitner, M. et al.
System: The UNT Digital Library
Water at an electrochemical interface - a simulation study (open access)

Water at an electrochemical interface - a simulation study

The results of molecular dynamics simulations of the properties of water in an aqueous ionic solution close to an interface with a model metallic electrode are described. In the simulations the electrode behaves as an ideally polarizable hydrophilic metal, supporting image charge interactions with charged species, and it is maintained at a constant electrical potential with respect to the solution so that the model is a textbook representation of an electrochemical interface through which no current is passing. We show how water is strongly attracted to and ordered at the electrode surface. This ordering is different to the structure that might be imagined from continuum models of electrode interfaces. Further, this ordering significantly affects the probability of ions reaching the surface. We describe the concomitant motion and configurations of the water and ions as functions of the electrode potential, and we analyze the length scales over which ionic atmospheres fluctuate. The statistics of these fluctuations depend upon surface structure and ionic strength. The fluctuations are large, sufficiently so that the mean ionic atmosphere is a poor descriptor of the aqueous environment near a metal surface. The importance of this finding for a description of electrochemical reactions is examined by calculating, …
Date: August 22, 2008
Creator: Willard, Adam; Reed, Stewart; Madden, Paul & Chandler, David
System: The UNT Digital Library
Angular Dependence of Jet Quenching Indicates Its Strong Enhancement Near the QCD Phase Transition (open access)

Angular Dependence of Jet Quenching Indicates Its Strong Enhancement Near the QCD Phase Transition

We study dependence of jet quenching on matter density, using 'tomography' of the fireball provided by RHIC data on azimuthal anisotropy v{sub 2} of high p{sub t} hadron yield at different centralities. Slicing the fireball into shells with constant (entropy) density, we derive a 'layer-wise geometrical limit' v{sub 2}{sup max} which is indeed above the data v{sub 2} < v{sub x}{sup max}. Interestingly, the limit is reached only if quenching is dominated by shells with the entropy density exactly in the near-T{sub c} region. We show two models that simultaneously describe the high p{sub t} v{sub 2} and R{sub AA} data and conclude that such a description can be achieved only if the jet quenching is few times stronger in the near-T{sub c} region relative to QGP at T > T{sub c}. One possible reason for that may be recent indications that the near-T{sub c} region is a magnetic plasma of relatively light color-magnetic monopoles.
Date: October 22, 2008
Creator: Liao, Jinfeng & Shuryak, Edward
System: The UNT Digital Library
Joint seismic-geodynamic-mineral physical modelling of African geodynamics: A reconciliation of deep-mantle convection with surface geophysical constraints (open access)

Joint seismic-geodynamic-mineral physical modelling of African geodynamics: A reconciliation of deep-mantle convection with surface geophysical constraints

Recent progress in seismic tomography provides the first complete 3-D images of the combined thermal and chemical anomalies that characterise the unique deep mantle structure below the African continent. With these latest tomography results we predict flow patterns under Africa that reveal a large-scale, active hot upwelling, or superplume, below the western margin of Africa under the Cape Verde Islands. The scale and dynamical intensity of this West African superplume (WASP) is comparable to that of the south African superplume (SASP) that has long been assumed to dominate the flow dynamics under Africa. On the basis of this new tomography model, we find the dynamics of the SASP is strongly controlled by chemical contributions to deep mantle buoyancy that significantly compensate its thermal buoyancy. In contrast, the WASP appears to be entirely dominated by thermal buoyancy. New calculations of mantle convection incorporating these two superplumes reveal that the plate-driving forces due to the flow generated by the WASP is as strong as that due to the SASP. We find that the chemical buoyancy of the SASP exerts a strong stabilising control on the pattern and amplitude of shallow mantle flow in the asthenosphere below the southern half of the African …
Date: August 22, 2008
Creator: Forte, A M; Quere, S; Moucha, R; Simmons, N A; Grand, S P; Mitrovica, J X et al.
System: The UNT Digital Library
Quantitative Structure-Property Relationship Studies on Ostwald Solubility and Partition Coefficients of Organic Solutes in Ionic Liquids (open access)

Quantitative Structure-Property Relationship Studies on Ostwald Solubility and Partition Coefficients of Organic Solutes in Ionic Liquids

Article discussing quantitative structure-property relationship studies on Ostwald solubility and partition coefficients of organic solutes in ionic liquids.
Date: April 22, 2008
Creator: Katritzky, Alan R.; Kuanar, Minati; Stoyanova-Slavova, Iva B.; Slavov, Svetoslav H.; Dobchev, Dimitar A.; Karelson, Mati et al.
System: The UNT Digital Library
Solubility of Lamotrigine, Diazepam, and Clonazepam in Ethanol + Water Mixtures at 298.15 K (open access)

Solubility of Lamotrigine, Diazepam, and Clonazepam in Ethanol + Water Mixtures at 298.15 K

Article on the solubility of lamotrigine, diazepam, and clonazepam in ethanol + water mixtures at 298.15 K.
Date: December 22, 2008
Creator: Shayanfar, Ali; Fakhree, Mohammad Amin Abolghassemi; Acree, William E. (William Eugene) & Jouyban, Abolghasem
System: The UNT Digital Library
Correlation and Prediction of Partition Coefficients from the Gas Phase and from Water to Alkan-1-ols (open access)

Correlation and Prediction of Partition Coefficients from the Gas Phase and from Water to Alkan-1-ols

Article discussing correlation and prediction of partition coefficients from the gas phase and from water to alkan-1-ols.
Date: April 22, 2008
Creator: Abraham, M. H. (Michael H.); Nasezadeh, Asadollah & Acree, William E. (William Eugene)
System: The UNT Digital Library
Extracting (n,gamma) direct capture cross sections from Coulomb dissociation: application to 14C(n,gamma)15C (open access)

Extracting (n,gamma) direct capture cross sections from Coulomb dissociation: application to 14C(n,gamma)15C

A methodology for extracting neutron direct capture rates from Coulomb Dissociation data is developed and applied to the Coulomb dissociation of {sup 15}C on {sup 208}Pb at 68 MeV/nucleon. Full Continuum Discretized Coupled Channel calculations are performed and an asymptotic normalization coefficient is determined from a fit to the breakup data. Direct neutron capture calculations using the extracted asymptotic normalization coefficient provide (n, {gamma}) cross sections consistent with direct measurements. Our results show that the Coulomb Dissociation data can be reliably used for extracting the cross section for {sup 14}C(n,{gamma}){sup 15}C if the appropriate reaction theory is used. The resulting error bars are of comparable magnitude to those from the direct measurement.
Date: January 22, 2008
Creator: Summers, N. C. & Nunes, F. M.
System: The UNT Digital Library