An analysis of model tropospheric response to various forcings (open access)

An analysis of model tropospheric response to various forcings

None
Date: January 30, 2006
Creator: Hnilo, J J & Christy, J R
System: The UNT Digital Library
Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering (open access)

Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.
Date: January 30, 2009
Creator: Anders, Andre & Yushkov, Georgy Yu.
System: The UNT Digital Library
A cell nanoinjector based on carbon nanotubes (open access)

A cell nanoinjector based on carbon nanotubes

Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here we report the development of a nanoscale cell injection system-termed the nanoinjector-that uses carbon nanotubes to deliver cargo into cells. A single multi-walled carbon nanotube attached to an atomic force microscope tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this 'nanoneedle', followed by reductive cleavage of the disulfide bonds within the cell's interior, resulted in the release of cargo inside the cells. The capability of the nanoinjector was demonstrated by injection of protein-coated quantum dots into live human cells. Single-particle tracking was employed to characterize the diffusion dynamics of injected quantum dots in the cytosol. This new technique causes no discernible membrane or cell damage, and can deliver a discrete number of molecules to the cell's interior without the requirement of a carrier solvent.
Date: January 30, 2007
Creator: Chen, Xing; Kis, Andras; Zettl, Alex & Bertozzi, Carolyn R.
System: The UNT Digital Library
Vortex Characterization for Engineering Applications (open access)

Vortex Characterization for Engineering Applications

Realistic engineering simulation data often have features that are not optimally resolved due to practical limitations on mesh resolution. To be useful to application engineers, vortex characterization techniques must be sufficiently robust to handle realistic data with complex vortex topologies. In this paper, we present enhancements to the vortex topology identification component of an existing vortex characterization algorithm. The modified techniques are demonstrated by application to three realistic data sets that illustrate the strengths and weaknesses of our approach.
Date: January 30, 2008
Creator: Jankun-Kelly, M; Thompson, D S; Jiang, M; Shannahan, B & Machiraju, R
System: The UNT Digital Library
Is there a low energy enhancement in the photon strength function in molybdenum? (open access)

Is there a low energy enhancement in the photon strength function in molybdenum?

Recent claims of a low energy enhancement in the photon strength function of {sup 96}Mo are investigated. Using the DANCE detector the gamma-ray spectra following resonance neutron capture was measured. The spectrum fitting method was used to indirectly extract a photon strength function from the gamma-ray spectra. No strong low energy enhancement in the photon strength function was found.
Date: January 30, 2008
Creator: Sheets, S A
System: The UNT Digital Library
Visible Light Absorption of Binuclear TiOCoII Charge-Transfer UnitAssembled in Mesoporous Silica (open access)

Visible Light Absorption of Binuclear TiOCoII Charge-Transfer UnitAssembled in Mesoporous Silica

Grafting of CoII(NCCH3)2Cl2 onto mesoporous Ti-MCM-41 silicain acetonitrile solution affords binuclear Ti-O-CoII sites on the poresurface under complete replacement of the precursor ligands byinteractions with anchored Ti centers and the silica surface. The CoIIligand field spectrum signals that the Co centers are anchored on thepore surface in tetrahedral coordination. FT-infrared action spectroscopyusing ammonia gas adsorption reveals Co-O-Si bond modes at 831 and 762cm-1. No Co oxide clusters are observed in the as-synthesized material.The bimetallic moieties feature an absorption extending from the UV intothe visible to about 600 nm which is attributed to the TiIV-O-CoII?3TiIII-O-CoIII metal-to-metal charge-transfer (MMCT) transition. Thechromophore is absent in MCM-41 containing Ti and Co centers isolatedfrom each other; this material was synthesized by grafting CoII onto aTi-MCM-41 sample with the Ti centers protected by a cyclopentadienylligand. The result indicates that the appearance of the charge-transferabsorption requires that the metal centers are linked by an oxo bridge,which is additionally supported by XANES spectroscopy. The MMCTchromophore of Ti-O-CoII units has sufficient oxidation power to serve asvisible light electron pump for driving multi-electron transfer catalystsof demanding uphill reactions such as water oxidation.
Date: January 30, 2007
Creator: Han, Hongxian & Frei, Heinz
System: The UNT Digital Library
Synthesis of a Benzodiazepine-derived Rhodium NHC Complex by C-H Bond Activation (open access)

Synthesis of a Benzodiazepine-derived Rhodium NHC Complex by C-H Bond Activation

The synthesis and characterization of a Rh(I)-NHC complex generated by C-H activation of 1,4-benzodiazepine heterocycle are reported. This complex constitutes a rare example of a carbene tautomer of a 1,4-benzodiazepine aldimine stabilized by transition metal coordination and demonstrates the ability of the catalytically relevant RhCl(PCy{sub 3}){sub 2} fragment to induce NHC-forming tautomerization of heterocycles possessing a single carbene-stabilizing heteroatom. Implications for the synthesis of benzodiazepines and related pharmacophores via C-H functionalization are discussed.
Date: January 30, 2008
Creator: Bergman, Roberg G.; Gribble, Jr., Michael W. & Ellman, Jonathan A.
System: The UNT Digital Library
Searches for the Decays B0 to l+- tau-+ and B+ to l+ nu(L=e,mu) using Hadronic Tag Reconstruction (open access)

Searches for the Decays B0 to l+- tau-+ and B+ to l+ nu(L=e,mu) using Hadronic Tag Reconstruction

We present searches for the leptonic decays B{sup +} {yields} {ell}{sup +}{nu} and the lepton flavor violating decays B{sup 0} {yields} {ell}{sup {+-}}{tau}{sup {-+}}, where {ell} = e, {mu}, with data collected by the BABAR experiment at SLAC. This search demonstrates a novel technique in which we fully reconstruct the accompanying {bar B} in {Upsilon}(4S) {yields} B{bar B} events, and look for a monoenergetic lepton from the signal B decay. The signal yield is extracted from a fit to the signal lepton candidate momentum distribution in the signal B rest frame. Using a data sample of approximately 378 million B{bar B} pairs (342 fb{sup -1}), we find no evidence of signal in any of the decay modes. Branching fraction upper limits of {Beta}(B{sup +} {yields} e{sup +}{nu}) < 5.2 x 10{sup -6}, {Beta}(B{sup +} {yields} {mu}{sup +}{nu}) < 5.6 x 10{sup -6}, {Beta}(B{sup 0} {yields} e{sup +}{tau}{sup -}) < 2.8 x 10{sup -5} and {Beta}(B{sup 0} {yields} {mu}{sup +}{tau}{sup -}) < 2.2 x 10{sup -5}, are obtained at 90% confidence level.
Date: January 30, 2008
Creator: Aubert, Bernard; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prudent, X. et al.
System: The UNT Digital Library
The Standard Chemical-Thermodynamic Properties of Phosphorus and Some of its Key Compounds and Aqueous Species: An Evaluation of Differences between the Previous Recommendations of NBS/NIST and CODATA (open access)

The Standard Chemical-Thermodynamic Properties of Phosphorus and Some of its Key Compounds and Aqueous Species: An Evaluation of Differences between the Previous Recommendations of NBS/NIST and CODATA

The aqueous chemistry of phosphorus is dominated by P(V), which under typical environmental conditions (and depending on pH and concentration) can be present as the orthophosphate ions H{sub 3}PO{sub 4}{sup 0}(aq), H{sub 2}PO{sub 4}{sup -}(aq), HPO{sub 4}{sup 2-}(aq), or PO{sub 4}{sup 3-}(aq). Many divalent, trivalent, and tetravalent metal ions form sparingly soluble orthophosphate phases that, depending on the solution pH and concentrations of phosphate and metal ions, can be solubility limiting phases. Geochemical and chemical engineering modeling of solubilities and speciation requires comprehensive thermodynamic databases that include the standard thermodynamic properties for the aqueous species and solid compounds. The most widely used sources for standard thermodynamic properties are the NBS (now NIST) Tables (from 1982 and earlier; with a 1989 erratum) and the final CODATA evaluation (1989). However, a comparison of the reported enthalpies of formation and Gibbs energies of formation for key phosphate compounds and aqueous species, especially H{sub 2}PO{sub 4}{sup -}(aq) and HPO{sub 4}{sup 2-}(aq), shows a systematic and nearly constant difference of 6.3 to 6.9 kJ {center_dot} mol{sup -1} per phosphorus atom between these two evaluations. The existing literature contains numerous studies (including major data summaries) that are based on one or the other of these evaluations. …
Date: January 30, 2007
Creator: Rard, J A & Wolery, T J
System: The UNT Digital Library
Active RF Pulse Compression using Electrically Controlled Semiconductor Switches (open access)

Active RF Pulse Compression using Electrically Controlled Semiconductor Switches

In this paper, we will present our recent results on the research of the ultra-fast high power RF switches based on silicon. We have developed a switch module at X-band which can use a silicon window as the switch. The switching is realized by generation of carriers in the bulk silicon. The carriers can be generated electrically or/and optically. The electrically controlled switches use PIN diodes to inject carrier. We have built the PIN diode switches at X-band, with <300ns switching time. The optically controlled switches use powerful lasers to excite carriers. By combining the laser excitation and electrical carrier generation, significant reduction in the required power of both the laser and the electrical driver is expected. High power test is under going.
Date: January 30, 2008
Creator: Guo, J. & Tantawi, S. G.
System: The UNT Digital Library
How did matter gain the upper hand over antimatter? (open access)

How did matter gain the upper hand over antimatter?

Antimatter exists! We routinely make it in laboratories. For every familiar particle type we find a matching antiparticle with opposite charge, but exactly the same mass. For example, a positron with positive charge has the same mass as an electron; an antiproton with negative charge has the same mass as a proton. Antimatter occurs naturally all over the universe wherever high-energy particles collide. The laws of physics for antimatter are very, very similar to those for antimatter--so far we know only one tiny difference in them, a detail of the weak interactions of quarks that earned Makoto Kobayashi and Toshihide Maskawa a share of the 2008 Nobel Prize for Physics. Our understanding of the early Universe also tells us that after inflation ended equal amounts of matter and antimatter were produced. Today there's a lot of matter in the universe, but very little antimatter. This leaves a big question for cosmology. How did matter gain the upper hand over antimatter? It's a question at the root of our existence. Without this excess, there would be no stars, no Earth, and no us! When a particle meets its antiparticle, they annihilate each other in a flash of radiation. This process removed …
Date: January 30, 2009
Creator: Quinn, Helen
System: The UNT Digital Library
Quality Assurance Source Requirements Traceability Database (open access)

Quality Assurance Source Requirements Traceability Database

At the Yucca Mountain Project the Project Requirements Processing System assists in the management of relationships between regulatory and national/industry standards source criteria, and Quality Assurance Requirements and Description document (DOE/R W-0333P) requirements to create compliance matrices representing respective relationships. The matrices are submitted to the U.S. Nuclear Regulatory Commission to assist in the commission's review, interpretation, and concurrence with the Yucca Mountain Project QA program document. The tool is highly customized to meet the needs of the Office of Civilian Radioactive Waste Management Office of Quality Assurance.
Date: January 30, 2006
Creator: MURTHY, R., NAYDENOVA, A., DEKLEVER, R., BOONE, A.
System: The UNT Digital Library
Fabrication and Characterization of Nanolayer Capacitors (open access)

Fabrication and Characterization of Nanolayer Capacitors

None
Date: January 30, 2008
Creator: Chow, R & Ellis, A D
System: The UNT Digital Library
Spin Dependent Electron Transmission Through Ferromagnetic Thin Films (open access)

Spin Dependent Electron Transmission Through Ferromagnetic Thin Films

None
Date: January 30, 2007
Creator: Komesu, T; Waddill, G D & Tobin, J G
System: The UNT Digital Library
The Rosetta Resources CO2 Storage Project - A WESTCARB Geologic Pilot Test (open access)

The Rosetta Resources CO2 Storage Project - A WESTCARB Geologic Pilot Test

WESTCARB, one of seven U.S. Department of Energypartnerships, identified (during its Phase I study) over 600 gigatonnesof CO2 storage capacity in geologic formations located in the Westernregion. The Western region includes the WESTCARB partnership states ofAlaska, Arizona, California, Nevada, Oregon and Washington and theCanadian province of British Columbia. The WESTCARB Phase II study iscurrently under way, featuring three geologic and two terrestrial CO2pilot projects designed to test promising sequestration technologies atsites broadly representative of the region's largest potential carbonsinks. This paper focuses on two of the geologic pilot studies plannedfor Phase II -referred to-collectively as the Rosetta-Calpine CO2 StorageProject. The first pilot test will demonstrate injection of CO2 into asaline formation beneath a depleted gas reservoir. The second test willgather data for assessing CO2 enhanced gas recovery (EGR) as well asstorage in a depleted gas reservoir. The benefit of enhanced oil recovery(EOR) using injected CO2 to drive or sweep oil from the reservoir towarda production well is well known. EaR involves a similar CO2 injectionprocess, but has received far less attention. Depleted natural gasreservoirs still contain methane; therefore, CO2 injection may enhancemethane production by reservoir repressurization or pressure maintenance.CO2 injection into a saline formation, followed by injection into adepleted natural …
Date: January 30, 2006
Creator: Trautz, Robert; Benson, Sally; Myer, Larry; Oldenburg, Curtis; Seeman, Ed; Hadsell, Eric et al.
System: The UNT Digital Library
Design and implementation of an emergency environmental responsesystem to protect migrating salmon in the lower San Joaquin River,California (open access)

Design and implementation of an emergency environmental responsesystem to protect migrating salmon in the lower San Joaquin River,California

In the past decade tens of millions of dollars have beenspent by water resource agencies in California to restore the nativesalmon fishery in the San Joaquin River and its major tributaries. Anexcavated deep water ship channel (DWSC), through which the river runs onits way to the Bay/Delta and Pacific Ocean, experiences episodes of lowdissolved oxygen which acts as a barrier to anadromous fish migration anda threat to the long-term survival of the salmon run. An emergencyresponse management system is under development to forecast theseepisodes of low dissolved oxygen and to deploy measures that will raisedissolved oxygen concentrations to prevent damage to the fisheryresource. The emergency response management system has been designed tointeract with a real-time water quality monitoring network and is servedby a comprehensive data management and forecasting model toolbox. TheBay/Delta and Tributaries (BDAT) Cooperative Data Management System is adistributed, web accessible database that contains terabytes ofinformation on all aspects of the ecology of the Bay/Delta and upperwatersheds. The complexity of the problem dictates data integration froma variety of monitoring programs. A unique data templating system hasbeen constructed to serve the needs of cooperating scientists who wish toshare their data and to simplify and streamline data uploading into themaster database. …
Date: January 30, 2006
Creator: Quinn, Nigel W.T. & Jacobs, Karl C.
System: The UNT Digital Library
Progress in Horizontal and Slant-Path Imaging Speckle Imaging (open access)

Progress in Horizontal and Slant-Path Imaging Speckle Imaging

The difficulty in terrestrial imaging over long horizontal or slant paths is that atmospheric aberrations and distortions reduce the resolution and contrast in images recorded at high resolution. This paper will describe the problem of horizontal-path imaging, briefly cover various methods for imaging over horizontal paths and then describe the speckle imaging method actively being pursued at LLNL. We will review some closer range (1-3 km range) imagery of people we have already published, as well as show new results of vehicles we have obtained over longer slant-range paths greater than 20 km.
Date: January 30, 2003
Creator: Carrano, C J
System: The UNT Digital Library
Multidimensional profiling of cell surface proteins and nuclear markers (open access)

Multidimensional profiling of cell surface proteins and nuclear markers

Cell membrane proteins play an important role in tissue architecture and cell-cell communication. We hypothesize that segmentation and multidimensional characterization of the distribution of cell membrane proteins, on a cell-by-cell basis, enable improved classification of treatment groups and identify important characteristics that can otherwise be hidden. We have developed a series of computational steps to (i) delineate cell membrane protein signals and associate them with a specific nucleus; (ii) compute a coupled representation of the multiplexed DNA content with membrane proteins; (iii) rank computed features associated with such a multidimensional representation; (iv) visualize selected features for comparative evaluation through heatmaps; and (v) discriminate between treatment groups in an optimal fashion. The novelty of our method is in the segmentation of the membrane signal and the multidimensional representation of phenotypic signature on a cell-by-cell basis. To test the utility of this method, the proposed computational steps were applied to images of cells that have been irradiated with different radiation qualities in the presence and absence of other small molecules. These samples are labeled for their DNA content and E-cadherin membrane proteins. We demonstrate that multidimensional representations of cell-by-cell phenotypes improve predictive and visualization capabilities among different treatment groups, and identify hidden …
Date: January 30, 2009
Creator: Han, Ju; Chang, Hang; Andarawewa, Kumari; Yaswen, Paul; Helen Barcellos-Hoff, Mary & Parvin, Bahram
System: The UNT Digital Library
Evidence for residual elastic strain in deformed natural quartz (open access)

Evidence for residual elastic strain in deformed natural quartz

Residual elastic strain in naturally deformed, quartz-containing rocks can be measured quantitatively in a petrographic thin section with high spatial resolution using Laue microdiffraction with white synchrotron x-rays. The measurements with a resolution of one micrometer allow the quantitative determination of the deviatoric strain tensor as a function of position within the crystal investigated. The observed equivalent strain values of 800-1200 microstrains represent a lower bound of the actual preserved residual strain in the rock, since the stress component perpendicular to the cut sample surface plane is released. The measured equivalent strain translates into an equivalent stress in the order of {approx} 50 MPa.
Date: January 30, 2009
Creator: Kunz, Martin; Chen, Kai; Tamura,Nobumichi & Wenk, Hans-Rudolf
System: The UNT Digital Library
Oxidation Kinetics of High Strength Low Alloy Steels at Elevated Temperatures (open access)

Oxidation Kinetics of High Strength Low Alloy Steels at Elevated Temperatures

None
Date: January 30, 2008
Creator: Talekar, Anjali; Chandra, Dhanesh; Chellappa, Raja; Daemen, Jaak; Tamura, Nobumichi & Kunz, Martin
System: The UNT Digital Library
Is the world shrinking or are we getting bigger? (open access)

Is the world shrinking or are we getting bigger?

None
Date: January 30, 2009
Creator: Alexandre, Melanie
System: The UNT Digital Library
Amplitude Dependence of Time of Flight. (open access)

Amplitude Dependence of Time of Flight.

Machida found in tracking studies [Shinji Machida, presentation at the FFAG05 Workshop, Kyoto University Research Reactor Institute, Osaka, Japan, 5-9 December 2005] that the time of flight in a linear non-scaling FFAG depended on the transverse amplitude of the particles. I compute a relationship between the transverse amplitude dependence of the time of flight and the variation of tune with energy and explain its physical origin.
Date: January 30, 2006
Creator: Berg, J. S.
System: The UNT Digital Library
A Numerical Investigation into the Anomalous Slight NOx Increase when Burning Biodiesel: A New (Old) Theory (open access)

A Numerical Investigation into the Anomalous Slight NOx Increase when Burning Biodiesel: A New (Old) Theory

Biodiesel is a notable alternative to petroleum derived diesel fuel because it comes from natural domestic sources and thus reduces dependence on diminishing petroleum fuel from foreign sources, it likely lowers lifecycle greenhouse gas emissions, and it lowers an engine's emission of most pollutants as compared to petroleum derived diesel. However, the use of biodiesel often slightly increases a diesel engine's emission of smog forming nitrogen oxides (NO{sub x}) relative to petroleum diesel. In this paper, previously proposed theories for this slight NOx increase are reviewed, including theories based on biodiesel's cetane number, which leads to differing amounts of charge preheating, and theories based on the fuel's bulk modulus, which affects injection timing. This paper proposes an additional theory for the slight NO{sub x} increase of biodiesel. Biodiesel typically contains more double bonded molecules than petroleum derived diesel. These double bonded molecules have a slightly higher adiabatic flame temperature, which leads to the increase in NOx production for biodiesel. Our theory was verified using numerical simulations to show a NOx increase, due to the double bonded molecules, that is consistent with observation. Further, the details of these numerical simulations show that NOx is predominantly due to the Zeldovich mechanism.
Date: January 30, 2007
Creator: Ban-Weiss, G. A.; Chen, J. Y.; Buchholz, B. A. & Dibble, R. W.
System: The UNT Digital Library
Summary of the FFAG05 Workshop at KEK (open access)

Summary of the FFAG05 Workshop at KEK

The FFAG05 workshop at KEK is one in a series of important annual gatherings of scientists working in the area of fixed field alternating gradient accelerators (FFAGs). At this workshop, we heard of many FFAG designs that are in operation, under construction, and in the planning stages. These machines are being used for a wide variety of applications. We also had a great deal of discussion of some of the theoretical aspects of FFAG design. This paper attempts to give a coherent summary of the workshop, and hopefully serves as an introduction to the more detailed papers in the workshop proceedings.
Date: January 30, 2006
Creator: Berg, J. S.
System: The UNT Digital Library