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Development of nanostructured and surface modified semiconductors for hybrid organic-inorganic solar cells.

Description: Solar energy conversion is increasingly being recognized as one of the principal ways to meet future energy needs without causing detrimental environmental impact. Hybrid organic-inorganic solar cells (SCs) are attracting particular interest due to the potential for low cost manufacturing and for use in new applications, such as consumer electronics, architectural integration and light-weight sensors. Key materials advantages of these next generation SCs over conventional semiconductor SCs are … more
Date: September 1, 2008
Creator: Hsu, Julia, W. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Sulfidation of Cadmium at the Nanoscale

Description: We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that … more
Date: May 22, 2008
Creator: Cabot, Andreu; Smith, Rachel; Yin, Yadong; Zheng, Haimei; Reinhard, Bjorn; Liu, Haitao et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

Description: Among the olivine-structured metal phosphate family, LiMnPO{sub 4} exhibits a high discharge potential (4V), which is still compatible with common electrolytes, making it interesting for use in the next generation of Li ion batteries. The extremely low electronic conductivity of this material severely limits its electrochemical performance, however. One strategy to overcome this limitation is to make LiMnPO{sub 4} nanoparticulate to decrease the diffusion distance. Another is to add a carbon or… more
Date: May 15, 2008
Creator: Chen, Jiajun; Doeff, Marca M. & Wang, Ruigang
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Origins of the Rate Enhancement in LiNi0.4Co0.2-yAlyMn0.4O2 (0<y<_0.2) Cathode Materials

Description: Recently, much research has been directed towards finding a replacement cathode material for LiCoO{sub 2} combining high performance with lower cost and toxicity. One promising candidate material is the mixed transition metal oxide LiNi{sub 0.4}Co{sub 0.2}Mn{sub 0.4}O{sub 2}, which delivers 180 mAh/g below 4.4 V versus Li/Li{sup +} (1, 2). However, in this material, there is 4% anti-site cation mixing, which hinders the mobility of lithium within the lattice, adversely affecting its rate perfor… more
Date: May 29, 2008
Creator: Doeff, Marca M; Wilcox, James & Doeff, Marca M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The effect of head-on beam-beam compensation on the stochastic boundaries and particle diffusion in RHIC.

Description: To compensate the effects from the head-on beam-beam interactions in the polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), an electron lens (elens) is proposed to collide head-on with the proton beam. We used an extended version of SixTrack for multiparticle beam-beam simulation in order to study the effect of the e-lens on the stochastic boundary and also on diffusion. The stochastic boundary was analyzed using Lyapunov exponents and the diffusion was characterized as t… more
Date: June 23, 2008
Creator: Abreu,N.; Beebe-Wang, J.; FischW; Luo, Y. & Robert-Demolaize, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Small, Inexpensive Combined NOx Sensor and O2 Sensor

Description: It has been successfully demonstrated in this program that a zirconia multilayer structure with rhodium-based porous electrodes performs well as an amperometric NOx sensor. The sensitivity of the sensor bodies operating at 650 to 700 C is large, with demonstrated current outputs of 14 mA at 500 ppm NOx from sensors with 30 layers. The sensor bodies are small (4.5 x 4.2 x 3.1 mm), rugged, and inexpensive. It is projected the sensor bodies will cost $5 - $10 in production. This program has built … more
Date: September 8, 2008
Creator: Lawless, W. N. & C. F. Clark, Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Investigation of Junction Properties in CdS/CdTe Solar Cells and Their Correlation to Device Properties: Preprint

Description: Secondary-ion mass spectrometry analysis of the CdS/CdTe interface shows that S diffusion in CdTe increases with substrate temperature and CdCl2 heat treatment. There is also an accumulation of Cl at the interface for CdCl2-treated samples. Modulated photo-reflectance studies shows that devices with CdCl2 heat treatment and open-circuit voltage (Voc) of 835 mV have a distinct high electric-field region in the layer with bandgap of 1.45 eV. Electron-beam induced current measurements reveal a one… more
Date: May 1, 2008
Creator: Dhere, R. G.; Zhang, Y.; Romero, M. J.; Asher, S. E.; Young, M.; To, B. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The influence of projectile neutron number in the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions

Description: Four isotopes of rutherfordium,254-257Rf, were produced by the 208Pb(48Ti, xn)256-xRf and 208Pb(50Ti, xn)258-xRf reactions (x = 1, 2) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Excitation functions were measured for the 1n and 2n exit channels. A maximum likelihood technique, which correctly accounts for the changing cross section at all energies subtended by the targets, was used to fit the 1n data to allow a more direct comparison between excitation functions obtained und… more
Date: July 11, 2008
Creator: Dragojevic, Irena; Dragojevic, I.; Gregorich, K. E.; Dullmann, Ch. E.; Garcia, M. A.; Gates, J. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Origin of Scale-Dependent Dispersivity and Its Implications For Miscible Gas Flooding

Description: Dispersive mixing has an important impact on the effectiveness of miscible floods. Simulations routinely assume Fickian dispersion, yet it is well established that dispersivity depends on the scale of measurement. This is one of the main reasons that a satisfactory method for design of field-scale miscible displacement processes is still not available. The main objective of this project was to improve the understanding of the fundamental mechanisms of dispersion and mixing, particularly at the … more
Date: September 30, 2008
Creator: Bryant, Steven; Johns, Russ; Lake, Larry & Harmon, Thomas
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of Concrete Wasteform Properties on Radionuclide Migration

Description: The objective of this investigation was to initiate numerous sets of concrete-soil half-cell tests to quantify 1) diffusion of I and Tc from concrete into uncontaminated soil after 1 and 2 years, 2) I and Re (set 1) and Tc (set 2) diffusion from fractured concrete into uncontaminated soil, and 3) evaluate the moisture distribution profile within the sediment half-cell. These half-cells will be section in FY2009 and FY2010. Additionally, 1) concrete-soil half-cells initiated during FY2007 using … more
Date: September 30, 2008
Creator: Wellman, Dawn M.; Bovaird, Chase C.; Mattigod, Shas V.; Parker, Kent E.; Ermi, Ruby M. & Wood, Marcus I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Long-term Variations of CO2 Trapped in Different Mechanisms in Deep Saline Formations: A Case Study of the Songliao Basin, China

Description: The geological storage of CO{sub 2} in deep saline formations is increasing seen as a viable strategy to reduce the release of greenhouse gases to the atmosphere. There are numerous sedimentary basins in China, in which a number of suitable CO{sub 2} geologic reservoirs are potentially available. To identify the multi-phase processes, geochemical changes and mineral alteration, and CO{sub 2} trapping mechanisms after CO{sub 2} injection, reactive geochemical transport simulations using a simple… more
Date: June 10, 2008
Creator: Zhang, Wei; Li, Yilian; Xu, Tianfu; Cheng, Huilin; Zheng, Yan & Xiong, Peng
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Isotope Tracer Studies of Diffusion in Sillicates and of Geological Transport Processes Using Actinide Elements

Description: The objectives were directed toward understanding the transport of chemical species in nature, with particular emphasis on aqueous transport in solution, in colloids, and on particles. Major improvements in measuring ultra-low concentrations of rare elements were achieved. We focused on two areas of studies: (1) Field, laboratory, and theoretical studies of the transport and deposition of U, Th isotopes and their daughter products in natural systems; and (2) Study of calcium isotope fractionati… more
Date: July 31, 2008
Creator: Wasserburg, Gerald J
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Numerical Modeling Studies of The Dissolution-Diffusion-Convection ProcessDuring CO2 Storage in Saline Aquifers

Description: For purposes of geologic storage, CO2 would be injected into saline formations at supercritical temperature and pressure conditions, and would form a separate phase that is immiscible with the aqueous phase (brine). At typical subsurface temperature and pressure conditions, supercritical CO2 (scCO2) has lower density than the aqueous phase and would experience an upward buoyancy force. Accordingly, the CO2 is expected to accumulate beneath the caprock at the top of the permeable interval, and c… more
Date: November 17, 2008
Creator: Pruess, Karsten & Zhang, Keni
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effects of Cu Diffusion from ZnTe:Cu/Ti Contacts on Carrier Lifetime of CdS/CdTe Thin Film Solar Cells: Preprint

Description: We study the performance of CdS/CdTe thin film PV devices processed with a ZnTe:Cu/Ti contact to investigate how carrier lifetime in the CdTe layer is affected by Cu diffusion from the contact.
Date: May 1, 2008
Creator: Gessert, T. A.; Metzger, W. K.; Asher, S. E.; Young, M. R.; Johnston, S.; Dhere, R. G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Soret Effect in Naturally Propagating, Premixed, Lean, Hydrogen-Air Flames

Description: Comparatively little attention has been given to multicomponent diffusion effects in lean hydrogen-air flames, in spite of the importance of these flames in safety and their potential importance to future energy technologies. Prior direct numerical simulations either have considered only the mixture-averaged transport model, or have been limited to stabilized flames that do not exhibit the thermo-diffusive instability. The so-called full, multicomponent transport model with cross-diffusion is f… more
Date: June 30, 2008
Creator: Grcar, Joseph F.; Grcar, Joseph F.; Bell, John B. & Day, Marcus S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

EXTENSION OF THE 1D FOUR-GROUP ANALYTIC NODAL METHOD TO FULL MULTIGROUP

Description: In the mid 80’s, a four-group/two-region, entirely analytical 1D nodal benchmark appeared. It was readily acknowledged that this special case was as far as one could go in terms of group number and still achieve an analytical solution. In this work, we show that by decomposing the solution to the multigroup diffusion equation into homogeneous and particular solutions, extension to any number of groups is a relatively straightforward exercise using the mathematics of linear algebra.
Date: September 1, 2008
Creator: Ganapol, B. D. & Nigg, D. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

Description: The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional… more
Date: May 15, 2008
Creator: Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi & Gullberg, Grant T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Determination of late-time Gamma-Ray (60Co) sensitivity of single diffusion Lot 2N2222A transistors.

Description: Sandia National Laboratories (SNL) has embarked on a program to develop a methodology to use damage relations techniques (alternative experimental facilities, modeling, and simulation) to understand the time-dependent effects in transistors (and integrated circuits) caused by neutron irradiations in the Sandia Pulse Reactor-III (SPR-III) facility. The development of these damage equivalence techniques is necessary since SPR-III was shutdown in late 2006. As part of this effort, the late time {g… more
Date: August 1, 2008
Creator: DePriest, Kendall Russell; Kajder, Karen C. & Peters, Curtis D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Recovery Discontinuous Galerkin Jacobian-free Newton-Krylov Method for all-speed flows

Description: There is an increasing interest to develop the next generation simulation tools for the advanced nuclear energy systems. These tools will utilize the state-of-art numerical algorithms and computer science technology in order to maximize the predictive capability, support advanced reactor designs, reduce uncertainty and increase safety margins. In analyzing nuclear energy systems, we are interested in compressible low-Mach number, high heat flux flows with a wide range of Re, Ra, and Pr numbers.… more
Date: July 1, 2008
Creator: Park, HyeongKae; Nourgaliev, Robert; Mousseau, Vincent & Knoll, Dana
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Direct Numerical Simulation of Interfacial Flows: Implicit Sharp-Interface Method (I-SIM)

Description: In recent work (Nourgaliev, Liou, Theofanous, JCP in press) we demonstrated that numerical simulations of interfacial flows in the presence of strong shear must be cast in dynamically sharp terms (sharp interface treatment or SIM), and that moreover they must meet stringent resolution requirements (i.e., resolving the critical layer). The present work is an outgrowth of that work aiming to overcome consequent limitations on the temporal treatment, which become still more severe in the presence … more
Date: January 1, 2008
Creator: Nourgaliev, Robert; Theofanous, Theo; Park, HyeongKae; Mousseau, Vincent & Knoll, Dana
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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