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Final technical report. [Heterogeneous nucleation and growth in metal alloys]

Description: We have refined a heat treatment to obtain coherent, heterogeneous nucleation of precipitates on dislocations in a high purity binary alloy. This allowed, for the first time, a quantitative comparison to be made for coherent heterogeneous nucleation. This part of the research resulted from our concern about the role of dislocations in sub-boundaries in aluminum alloys and directed us to first examine isolated dislocations in the binary Al-Li systems. We were able to design the experiment so the… more
Date: September 14, 1997
Creator: Shiflet, G.J.
Partner: UNT Libraries Government Documents Department
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Direct real-space observation of nearly stochastic behavior in magnetization reversal process on a nanoscale

Description: We report a non-deterministic nature in the magnetization reversal of nanograins of CoCrPt alloy film. Magnetization reversal process of CoCrPt alloy film is investigated using high resolution soft X-ray microscopy which provides real space images with a spatial resolution of 15 nm. Domain nucleation sites mostly appear stochastically distributed within repeated hysteretic cycles, where the correlation increases as the strength of the applied magnetic field increases in the descending and ascen… more
Date: June 1, 2007
Creator: Im, M. Y.; Kim, D. H.; Lee, K. D.; Fischer, P. & Shin, S. C.
Partner: UNT Libraries Government Documents Department
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Studies of the viscoelastic properties of water confined between surfaces of specified chemical nature.

Description: This report summarizes the work completed under the Laboratory Directed Research and Development (LDRD) project 10-0973 of the same title. Understanding the molecular origin of the no-slip boundary condition remains vitally important for understanding molecular transport in biological, environmental and energy-related processes, with broad technological implications. Moreover, the viscoelastic properties of fluids in nanoconfinement or near surfaces are not well-understood. We have critically r… more
Date: September 1, 2010
Creator: Houston, Jack E.; Grest, Gary Stephen; Moore, Nathan W. & Feibelman, Peter J.
Partner: UNT Libraries Government Documents Department
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Heterogeneous nucleation of ice on anthropogenic organic particles collected in Mexico City

Description: This study reports on heterogeneous ice nucleation activity of predominantly organic (or coated with organic material) anthropogenic particles sampled within and around the polluted environment of Mexico City. The onset of heterogeneous ice nucleation was observed as a function of particle temperature (Tp), relative humidity (RH), nucleation mode, and particle chemical composition which is influenced by photochemical atmospheric aging. Particle analyses included computer controlled scanning ele… more
Date: June 20, 2010
Creator: Knopf, D. A.; Wang, B.; Laskin, A.; Moffet, R. C. & Gilles, M. K.
Partner: UNT Libraries Government Documents Department
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Kinetic Treatment of the Nucleation in Supersaturated Vapors

Description: The equations of the individual processes of self nucleation are utilized through an electrical analogy to obtain the nucleation frequency. This process is shown to be shorter and less subject to error than that of previous investigators since the appearance of indeterminant integration constants is completely avoided. With the nucleation frequencies of crystals and spheres the Ostwald law of stages is reviewed and modified.
Date: September 1954
Creator: Becker, R. & Döring, Werner
Partner: UNT Libraries Government Documents Department
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Synthesis of silicon and germanium nanowires.

Description: The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant depend… more
Date: November 1, 2007
Creator: Clement, Teresa J. (Arizona State University) & Hsu, Julia W. P.
Partner: UNT Libraries Government Documents Department
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Secondary organic aerosol from ozone-initiated reactions with terpene-rich household products

Description: We analyzed secondary organic aerosol (SOA) data from a series of small-chamber experiments in which terpene-rich vapors from household products were combined with ozone under conditions analogous to product use indoors. Reagents were introduced into a continuously ventilated 198 L chamber at steady rates. Consistently, at the time of ozone introduction, nucleation occurred exhibiting behavior similar to atmospheric events. The initial nucleation burst and growth was followed by a period in whi… more
Date: January 1, 2008
Creator: Coleman, Beverly; Coleman, Beverly K.; Lunden, Melissa M.; Destaillats, Hugo & Nazaroff, William W.
Partner: UNT Libraries Government Documents Department
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Program Abstracts: Formation and Growth of Atmospheric Aerosols

Description: DOE provided $11,000 to sponsor the Workshop on New Particle Formation in the Atmosphere, which was held at The Riverwood Inn and Conference Center near Minneapolis, MN from September 7 to 9, 2006. Recent work has shown that new particle formation is an important atmospheric process that must be better understood due to its impact on cloud cover and the Earth's radiation balance. The conference was an informal gathering of atmospheric and basic scientists with expertise pertinent to this topic.… more
Date: September 7, 2006
Creator: McMurry, Peter H. & Kulmala, Markku
Partner: UNT Libraries Government Documents Department
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Helium nano-bubble evolution in aging metal tritides.

Description: A continuum-scale, evolutionary model of helium (He) nano-bubble nucleation, growth and He release for aging bulk metal tritides is presented which accounts for major features of the experimental database. Bubble nucleation, modeled as self-trapping of interstitially diffusing He atoms, is found to occur during the first few days following tritium introduction into the metal and is sensitive to the He diffusivity and pairing energy. An effective helium diffusivity of 0.3 x 10{sup -16} cm{sup 2}… more
Date: May 1, 2004
Creator: Cowgill, Donald F.
Partner: UNT Libraries Government Documents Department
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Field driven ferromagnetic phase nucleation and propagation from the domain boundaries in antiferromagnetically coupled perpendicular anisotropy films

Description: We investigate the reversal process in antiferromagnetically coupled [Co/Pt]{sub X-1}/{l_brace}Co/Ru/[Co/Pt]{sub X-1}{r_brace}{sub 16} multilayer films by combining magnetometry and Magnetic soft X-ray Transmission Microscopy (MXTM). After out-of-plane demagnetization, a stable one dimensional ferromagnetic (FM) stripe domain phase (tiger-tail phase) for a thick stack sample (X=7 is obtained), while metastable sharp antiferromagnetic (AF) domain walls are observed in the remanent state for a th… more
Date: December 9, 2008
Creator: Hauet, Thomas; Gunther, Christian M.; Hovorka, Ondrej; Berger, Andreas; Im, Mi-Young; Fischer, Peter et al.
Partner: UNT Libraries Government Documents Department
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Transverse field-induced nucleation pad switching modes during domain wall injection

Description: We have used magnetic transmission X-ray microscopy (M-TXM) to image in-field magnetization configurations of patterned Ni{sub 80}Fe{sub 20} domain wall 'injection pads' and attached planar nanowires. Comparison with micromagnetic simulations suggests that the evolution of magnetic domains in rectangular injection pads depends on the relative orientation of closure domains in the remanent state. The magnetization reversal pathway is also altered by the inclusion of transverse magnetic fields. T… more
Date: March 12, 2010
Creator: Bryan, M. T.; Fry, P. W.; Schrefl, T.; Gibbs, M. R. J.; Allwood, D. A.; Im, M.-Y. et al.
Partner: UNT Libraries Government Documents Department
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Rate Equation Theory for Island Sizes and Capture Zone Areas in Submonolayer Deposition: Realistic Treatment of Spatial Aspects of Nucleation

Description: Extensive information on the distribution of islands formed during submonolayer deposition is provided by the joint probability distribution (JPD) for island sizes, s, and capture zone areas, A. A key ingredient determining the form of the JPD is the impact of each nucleation event on existing capture zone areas. Combining a realistic characterization of such spatial aspects of nucleation with a factorization ansatz for the JPD, we provide a concise rate equation formulation for the variation w… more
Date: December 5, 2002
Creator: Evans, J. W.; Li, M. & Bartelt, M. C.
Partner: UNT Libraries Government Documents Department
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Modeling and Characterization of Recompressed Damaged Materials

Description: Ductile metals subjected to shock loading can develop internal damage through nucleation growth and coalescence of voids. The extent of damage can range from a well-defined spall plane induced by light shocks to more widespread damage caused by strong shocks. Because damage materials are often part of a dynamic system, significant additional deformation can occur in extensively damaged materials. To represent material behavior in simulation codes for stockpile stewardship calculations, both the… more
Date: December 16, 2002
Creator: Becker, R; Belak, J & Campbell, G
Partner: UNT Libraries Government Documents Department
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Time-Resolved Studies of Laser Damage Processes in DKDP Crystals

Description: The authors have used a 3-color imaging technique to obtain time-resolved series of images during nanosecond laser damage in bulk DKDP crystals. In contrast to single-pump, single-probe time-resolved imaging techniques, they are able to correlate behavior during single damage events. This enables us to observe a range of morphological dynamics that is otherwise difficult to study, including: the propagation of elastic sound waves and the liquid/solid melt front from the damage nucleation site a… more
Date: February 12, 2000
Creator: Jiang, H; McNary, R; Tom, H; Yan, M; Radousky, H & Demos, S
Partner: UNT Libraries Government Documents Department
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Theoretical Studies of Nucleation Kinetics and Nanodroplet Microstructure

Description: The goals of this project were to (1) explore ways of bridging the gap between fundamental molecular nucleation theories and phenomenological approaches based on thermodynamic reasoning, (2) test and improve binary nucleation theory, and (3) provide the theoretical underpinning for a powerful new experimental technique, small angle neutron scattering (SANS) from nanodroplet aerosols, that can probe the compositional structure of nanodroplets. This report summarizes the accomplishments of this p… more
Date: January 31, 2009
Creator: Wilemski, Gerald
Partner: UNT Libraries Government Documents Department
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Preparation of pHEMA-CP composites with high interfacial adhesionvia template-driven mineralization

Description: We report a template-driven nucleation and mineral growth process for the high-affinity integration of calcium phosphate (CP) with a poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel scaffold. A mineralization technique was developed that exposes carboxylate groups on the surface of crosslinked pHEMA, promoting high-affinity nucleation and growth of calcium phosphate on the surface along with extensive calcification of the hydrogel interior. External factors such as the heating rate, the agita… more
Date: December 5, 2002
Creator: Song, Jie; Saiz, Eduardo & Bertozzi, Carolyn R.
Partner: UNT Libraries Government Documents Department
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Experimental and Theoretical Studies of Nucleation in Supercooled Liquid Silicon. Final Program Report

Description: The original objectives of the present program consisted of two specific nucleation-related research activities; (1) to provide a set of experimental data that will enable the quantitative examination of classical nucleation theory, and (2) to describe the phenomenon of nucleation by developing general expressions of nucleation that include both the thermal and athermal components and that correctly consider and incorporate the transient effects that arise from the nonstationary cluster distrib… more
Date: April 29, 2004
Creator: Im, J.
Partner: UNT Libraries Government Documents Department
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Stifling of Crevice Corrosion in Alloy 22

Description: Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that … more
Date: June 8, 2005
Creator: Mon, K G; Gordon, G M & Rebak, R B
Partner: UNT Libraries Government Documents Department
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