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Laser-generated shock-wave experiments in metals above 1 TPa (open access)

Laser-generated shock-wave experiments in metals above 1 TPa

Some initial experiments are described which form part of a new program aimed at significantly extending the range of high pressures and densities which may be explored in laboratory equation-of-state (EOS) experiments. These experiments will utilize high-energy lasers, such as those employed in the Laser Fusion Program at Lawrence Livermore Laboratory (LLL), to generate intense shock waves in materials of interest.
Date: January 31, 1978
Creator: Trainor, R. J.; Shaner, J. W.; Auerbach, J. M. & Phillion, D. W.
System: The UNT Digital Library
Fluorescent scattering by molecules embedded in small particles. Progress report, February 1, 1981-January 31, 1982 (open access)

Fluorescent scattering by molecules embedded in small particles. Progress report, February 1, 1981-January 31, 1982

In earlier work a model of fluorescent and Raman scattering by active molecules represented as classical electric dipoles embedded in small particles was developed. The intensity and angular distribution of the inelastically scattered radiation was shown to depend on the geometric and optical properties of the particle. The model was originally developed for particles having spherical shape and later extended to concentric spheres, cylinders, and prolate spheroids. The active molecules were originally assumed to be isotropically polarizable. The model has been recently extended to certain types of anisotropically polarizable molecules. The model had also been applied to particles having internal structure.
Date: January 31, 1982
Creator: Chew, H. & McNulty, P.J.
System: The UNT Digital Library
Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna (open access)

Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna

Previous work on intact thylakoid membranes showed that transient formation of a zeaxanthin radical cation was correlated with regulation of photosynthetic light-harvesting via energy-dependent quenching. A molecular mechanism for such quenching was proposed to involve charge transfer within a chlorophyll-zeaxanthin heterodimer. Using near infrared (880-1100 nm) transient absorption spectroscopy, we demonstrate that carotenoid (mainly zeaxanthin) radical cation generation occurs solely in isolated minor light-harvesting complexes that bind zeaxanthin, consistent with the engagement of charge transfer quenching therein. We estimated that less than 0.5percent of the isolated minor complexes undergo charge transfer quenching in vitro, whereas the fraction of minor complexes estimated to be engaged in charge transfer quenching in isolated thylakoids was more than 80 times higher. We conclude that minor complexes which bind zeaxanthin are sites of charge transfer quenching in vivo and that they can assume Non-quenching and Quenching conformations, the equilibrium LHC(N)<--> LHC(Q) of which is modulated by the transthylakoid pH gradient, the PsbS protein, and protein-protein interactions.
Date: January 31, 2008
Creator: Avenson, Thomas H.; Ahn, Tae Kyu; Zigmantas, Donatas; Niyogi, Krishna K.; Li, Zhirong; Ballottari, Matteo et al.
System: The UNT Digital Library
The morphologies of breast cancer cell lines in three-dimensionalassays correlate with their profiles of gene expression (open access)

The morphologies of breast cancer cell lines in three-dimensionalassays correlate with their profiles of gene expression

3D cell cultures are rapidly becoming the method of choice for the physiologically relevant modeling of many aspects of non-malignant and malignant cell behavior ex vivo. Nevertheless, only a limited number of distinct cell types have been evaluated in this assay to date. Here we report the first large scale comparison of the transcriptional profiles and 3D cell culture phenotypes of a substantial panel of human breast cancer cell lines. Each cell line adopts a colony morphology of one of four main classes in 3D culture. These morphologies reflect, at least in part, the underlying gene expression profile and protein expression patterns of the cell lines, and distinct morphologies were also associated with tumor cell invasiveness and with cell lines originating from metastases. We further demonstrate that consistent differences in genes encoding signal transduction proteins emerge when even tumor cells are cultured in 3D microenvironments.
Date: January 31, 2007
Creator: Kenny, Paraic A.; Lee, Genee Y.; Myers, Connie A.; Neve, RichardM.; Semeiks, Jeremy R.; Spellman, Paul T. et al.
System: The UNT Digital Library
Causes of Ocean Surface temperature Changes in Atlantic andPacific Topical Cyclogenesis Regions (open access)

Causes of Ocean Surface temperature Changes in Atlantic andPacific Topical Cyclogenesis Regions

Previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity. We use climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions. The observed SST increases in these regions range from 0.32 to 0.67 C over the 20th century. The 22 climate models examined here suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system, even under conservative assumptions regarding the magnitude of this variability. Model simulations that include external forcing by combined anthropogenic and natural factors are generally capable of replicating observed SST changes in both tropical cyclogenesis regions.
Date: January 31, 2006
Creator: Santer, B. D.; Wigley, T. M. L.; Gleckler, P. J.; Bonfils, C.; Wehner, M. F.; AchutaRao, K. et al.
System: The UNT Digital Library
Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability (open access)

Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability

This paper describes two stylized alternative visions inpopular currencyof how the power system might evolve to meet futurerequirements for the high quality electricity service that modern digitaleconomies demand, a supergrids paradigm and a dispersed paradigm. Some ofthe economics of the dispersed vision are explored. Economic perspectivesare presented on both the choice of homogeneous universal power qualityupstream in the electricity supply, and also on the extremelyheterogeneous require-ments of end-use loads. Finally, the potential roleof microgrids in delivering heterogeneous power quality is demonstratedby reference to two ongoing microgrid tests in the U.S. andJapan.
Date: January 31, 2007
Creator: Marnay, Chris
System: The UNT Digital Library
HYDROGEN EMBRITTLEMENT OF METALS: A PRIMER FOR THE FAILURE ANALYST (open access)

HYDROGEN EMBRITTLEMENT OF METALS: A PRIMER FOR THE FAILURE ANALYST

Hydrogen reduces the service life of many metallic components. Such reductions may be manifested as blisters, as a decrease in fatigue resistance, as enhanced creep, as the precipitation of a hydride phase and, most commonly, as unexpected, macroscopically brittle failure. This unexpected, brittle fracture is commonly termed hydrogen embrittlement. Frequently, hydrogen embrittlement occurs after the component has been is service for a period of time and much of the resulting fracture surface is distinctly intergranular. Many failures, particularly of high strength steels, are attributed to hydrogen embrittlement simply because the failure analyst sees intergranular fracture in a component that served adequately for a significant period of time. Unfortunately, simply determining that a failure is due to hydrogen embrittlement or some other form of hydrogen induced damage is of no particular help to the customer unless that determination is coupled with recommendations that provide pathways to avoid such damage in future applications. This paper presents qualitative and phenomenological descriptions of the hydrogen damage processes and outlines several metallurgical recommendations that may help reduce the susceptibility of a particular component or system to the various forms of hydrogen damage.
Date: January 31, 2008
Creator: Louthan, M
System: The UNT Digital Library
Effect of Structure on the Storage Characteristics of ManganeseOxide Electrode Materials (open access)

Effect of Structure on the Storage Characteristics of ManganeseOxide Electrode Materials

Eleven types of manganese-containing electrode materialswere subjected to long-term storage at 55oC in 1M LiPF6 ethylenecarbonate/dimethyl carbonate (EC/DMC) solutions. The amount of manganesedissolution observed depended upon the sample surface area, the averageMn oxidation state, the structure, and substitution levels of themanganese oxide. In some cases, structural changes such as solvateformation were exacerbated by the high temperature storage, andcontributed to capacity fading upon cycling even in the absence ofsignificant Mn dissolution. The most stable materials appear to beTi-substituted tunnel structures and mixed metal layered oxides with Mnin the +4 oxidation state.
Date: January 31, 2006
Creator: Park, Yong Joon & Doeff, Marca M.
System: The UNT Digital Library
Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions (open access)

Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions

The decay properties of {sup 290}116 and {sup 291}116, and the dependence of their production cross sections on the excitation energies of the compound nucleus, {sup 293}116, have been measured in the {sup 245}Cm({sup 48}Ca,xn){sup 293-x}116 reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the {sup 249}Cf+{sup 48}Ca reaction. They performed the element 118 experiment at two projectile energies, corresponding to {sup 297}118 compound nucleus excitation energies of E* = 29.2 {+-} 2.5 and 34.4 {+-} 2.3 MeV. During an irradiation with a total beam dose of 4.1 x 10{sup 19} {sup 48}Ca projectiles, three similar decay chains consisting of two or three consecutive {alpha} decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope {sup 294}118 (E{sub {alpha}} = 11.65 {+-} 0.06 MeV, T{sub {alpha}} = 0.89{sub -0.31}{sup +1.07} ms) produced in the 3n-evaporation channel of the {sup 249}Cf+{sup 48}Ca reaction with a maximum cross section of 0.5{sub -0.3}{sup +1.6} pb.
Date: January 31, 2006
Creator: Oganessian, Y. T.; Utyonkov, V. K.; Lobanov, Y. V.; Abdullin, F. S.; Polyakov, A. N.; Sagaidak, R. N. et al.
System: The UNT Digital Library
Dynamics of Propane in Silica Mesopores Formed upon PropyleneHydrogenation over Pt Nanoparticles by Time-Resolved FT-IRSpectroscopy (open access)

Dynamics of Propane in Silica Mesopores Formed upon PropyleneHydrogenation over Pt Nanoparticles by Time-Resolved FT-IRSpectroscopy

Propylene hydrogenation over Pt nanoparticles supported onmesoporous silica type SBA-15 was monitored by time-resolved FT-IRspectroscopy at 23 ms resolution using short propylene gas pulses thatjoined a continuous flow of hydrogen in N2 (1 atm total pressure).Experiments were conducted in the temperature range 323-413 K. Propanewas formed within 100 milliseconds or faster. The CH stretching regionrevealed distinct bands for propane molecules emerging inside thenanoscale channels of the silica support. Spectral analysis gave thedistribution of the propane product between support and surrounding gasphase as function of time. Kinetic analysis showed that the escape ofpropane molecules from the channels occurred within hundreds ofmilliseconds (3.1 + 0.4 s-1 at 383 K). A steady state distribution ofpropane between gas phase and mesoporous support is established as theproduct is swept from the catalyst zone by the continuous flow ofhydrogen co-reactant. This is the first direct spectroscopic observationof emerging products of heterogeneous catalysis on nanoporous supportsunder reaction conditions.
Date: January 31, 2007
Creator: Waslylenko, Walter & Frei, Heinz
System: The UNT Digital Library
Geological disposal investigations in granite at the Nevada test site (open access)

Geological disposal investigations in granite at the Nevada test site

The Climax stock at NTS was the site of weapons effects tests and is to be used for radwaste disposal studies. The layout of Climax and proposed experiments is illustrated. Geology of Climax is described briefly. Thermal tests showed the thermal conductivity to be essentially isotropic, only slightly temperature-dependent, and 3.0 W/m-/sup 0/K. Permeability is less than 1 nanodarcy. Plans for a spent fuel storage test and for rock mechanics tests are described. (DLC)
Date: January 31, 1979
Creator: Ballou, L. B.
System: The UNT Digital Library
Instrument reliability for high-level nuclear-waste-repository applications (open access)

Instrument reliability for high-level nuclear-waste-repository applications

Reliable instrumentation will be needed to evaluate the characteristics of proposed high-level nuclear-wasted-repository sites and to monitor the performance of selected sites during the operational period and into repository closure. A study has been done to assess the reliability of instruments used in Department of Energy (DOE) waste repository related experiments and in other similar geological applications. The study included experiences with geotechnical, hydrological, geochemical, environmental, and radiological instrumentation and associated data acquisition equipment. Though this paper includes some findings on the reliability of instruments in each of these categories, the emphasis is on experiences with geotechnical instrumentation in hostile repository-type environments. We review the failure modes, rates, and mechanisms, along with manufacturers modifications and design changes to enhance and improve instrument performance; and include recommendations on areas where further improvements are needed.
Date: January 31, 1983
Creator: Rogue, F.; Binnall, E. P. & Armantrout, G. A.
System: The UNT Digital Library
DOE`s perspective: Reaching success by standing on a three legged stool (open access)

DOE`s perspective: Reaching success by standing on a three legged stool

Gridlock, inertia, conflict, outrage, bureaucracy, obstruction, media sensationalizing, courts, and politicians. These are the things that characterize any attempt to implement a public policy today. It is worse today than it has ever been because the middle has dropped out of public opinion. We have today no consensus of public values. At Fernald, we have come to recognize that in order to achieve any success we must first build a public consensus about what success will look like. We do this through a three-part approach we call the three legged stool. It includes public information, management involvement, and person-to-person communication. Each of these elements is essential.
Date: January 31, 1995
Creator: Hamric, J. P. & Morgan, K. L.
System: The UNT Digital Library
A 250 GHz microwave interferometer for divertor experiments on DIII-D (open access)

A 250 GHz microwave interferometer for divertor experiments on DIII-D

A new 250 GHz, two-frequency microwave interferometer system has been developed to diagnose divertor plasmas on DIII-D. This diagnostic will measure the line-averaged density across both the inner and outer, lower divertor legs. With a cut-off density of over 7 {times} 10{sup 14} cm{sup {minus}3}, temporal measurements of ELMs, MARFs and plasma detachment are expected. The outer leg system will use a double pass method while the inner leg system will be single pass. Two special 3D carbon composite tiles are used, one to protect the microwave antennas mounted directly under the strike point and the other as the outer leg reflecting surface. Performance, design constraints, and the thermalmechanical design of the 3D carbon composite tiles are discussed.
Date: January 31, 1994
Creator: James, R. A.; Nilson, D. G.; Stever, R. D.; Hill, D. N. & Casper, T. A.
System: The UNT Digital Library
Nuclear processes involved in electronuclear breeding (open access)

Nuclear processes involved in electronuclear breeding

The nuclear processes considered in a recent LLL assessment of electronuclear breeding of fissile material are described. The nuclear cross sections and neutron yields measured in the MTA program (1949-1954), and the nuclear cascade calculations carried out then and in more recent times are briefly described. The probable advantage of deuterons over protons as particles to be accelerated is mentioned, and the need for a series of experiments to determine the choice of particle, optimum accelerator parameters and target system design is stressed.
Date: January 31, 1977
Creator: Heckrotte, W.
System: The UNT Digital Library
The QCD Phase Diagram: Large Nc, Quarkyonic Matter and the Triple Point (open access)

The QCD Phase Diagram: Large Nc, Quarkyonic Matter and the Triple Point

I discuss the phase diagram of QCD in the large N_c limit. Quarkyonic Matter is described. The properties of QCD matter as measured in the abundance of produced particles are shown to be consistent with this phase diagram. A possible triple point of Hadronic Mater, Deconfined Matter and Quarkyonic matter is shown to explain various behaviors of ratios of particles abundances seen in CERN fixed target experiments.
Date: January 31, 2010
Creator: McLerran, L.
System: The UNT Digital Library
An analysis of the finite-differenced, even-parity discrete-ordinates equations in slab geometry (open access)

An analysis of the finite-differenced, even-parity discrete-ordinates equations in slab geometry

Considerable effort has been expended in recent years in finding improved spatial differencing schemes for the neutron and radiation transport equations. Standard criteria used to select a candidate scheme are its order of spatial convergence for small mesh size and its positivity in the sense that positive solutions emerge from positive input data. More recently, it has become clear that truly robust schemes must behave well in diffusing regions and must be compatible with an effective iteration acceleration method. Recently, Morel and Larsen reported their work on a promising new method called the multiple balance method that has virtually all the desirable characteristics. Here we study a different approach to the problem by considering discrete-ordinates approximations to the even-parity transport equations. We analyze three spatial difference approaches: diamond differencing, cell-edge differencing, and cell-center differencing. For the case of isotropic scattering and sources, the latter two approaches are shown to be strictly positive, to be second-order accurate, to be compatible with derived diffusion synthetic acceleration methods, and to possess the necessary diffusion limits. Unlike previous work with the even-parity equation, we do not use finite elements or variational principles. 5 refs., 1 tab.
Date: January 31, 1990
Creator: Miller, W. F. Jr.
System: The UNT Digital Library
Image processing and control of a programmable spatial light modulator (open access)

Image processing and control of a programmable spatial light modulator

None
Date: January 31, 2011
Creator: Awwal, A.; Leach, R.; Brunton, G.; Tse, E.; Matone, J. & Heebner, J.
System: The UNT Digital Library
Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation, historical and projected changes. (open access)

Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation, historical and projected changes.

None
Date: January 31, 2013
Creator: Lamarque, J. F.; Dentener, F.; McConnell, J.; Ro, C. U.; Shaw, M.; Vet, R. et al.
System: The UNT Digital Library
Proceedings of a workshop on Applications of Accelerators (open access)

Proceedings of a workshop on Applications of Accelerators

This document is a compilation of material collected as the results of a workshop, Applications of Accelerators, held at the Stanford Linear Accelerator Center, 1--2 December 1993. The material collected here has been edited for style and to minimize duplication. Footnotes will identify the original source of the material. We believe that the reader will find that this document has something for every interest. There are applications in the fields of health, food preservation, energy, environmental monitoring and protection, and industrial processing. Man y of the examples discussed have already passed the demonstration stage. Most of the others are the subject of active accelerator research. Taken as a whole, the particle accelerator field contains a wealth of application opportunities, some already in use, and many more ready to be exploited.
Date: January 31, 1994
Creator: Herrmannsfeldt, W. B.; Sessler, A. M. & Alonso, J. R.
System: The UNT Digital Library
Separating Dark Physics from Physical Darkness: Minimalist Modified Gravity vs. Dark Energy (open access)

Separating Dark Physics from Physical Darkness: Minimalist Modified Gravity vs. Dark Energy

The acceleration of the cosmic expansion may be due to a new component of physical energy density or a modification of physics itself. Mapping the expansion of cosmic scales and the growth of large scale structure in tandem can provide insights to distinguish between the two origins. Using Minimal Modified Gravity (MMG) - a single parameter gravitational growth index formalism to parameterize modified gravity theories - we examine the constraints that cosmological data can place on the nature of the new physics. For next generation measurements combining weak lensing, supernovae distances, and the cosmic microwave background we can extend the reach of physics to allow for fitting gravity simultaneously with the expansion equation of state, diluting the equation of state estimation by less than 25percent relative to when general relativity is assumed, and determining the growth index to 8percent. For weak lensing we examine the level of understanding needed of quasi- and nonlinear structure formation in modified gravity theories, and the trade off between stronger precision but greater susceptibility to bias as progressively more nonlinear information is used.
Date: January 31, 2007
Creator: Huterer, Dragan & Linder, Eric V.
System: The UNT Digital Library
Harmonic resolution as a holographic quantum number (open access)

Harmonic resolution as a holographic quantum number

The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.
Date: January 31, 2004
Creator: Bousso, Raphael
System: The UNT Digital Library
Turbulent Equipartition Theory of Toroidal Momentum Pinch (open access)

Turbulent Equipartition Theory of Toroidal Momentum Pinch

The mode-independet part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density [Hahm et al., Phys. Plasmas 14,072302 (2007)] which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of "magnetically weighted angular momentum density," nmi U|| R⁄B2, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustratd that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.
Date: January 31, 2008
Creator: Hahm, T. S.; Diamond, P. H.; Gurcan, O. D. & Rewaldt, G.
System: The UNT Digital Library
Thenature of marbled Terra Sigillata slips: a combined mu XRF and mu XRD investigation (open access)

Thenature of marbled Terra Sigillata slips: a combined mu XRF and mu XRD investigation

In addition to the red terra sigillata production, the largest Gallic workshop (La Graufesenque) made a special type of terra sigillata, called 'marbled' by the archaeologists. Produced exclusively on this site, this pottery is characterized by a surface finish made of a mixture of yellow and red slips. Because the two slips are intimately mixed, it is difficult to obtain the precise composition of one of the two constituents without contamination by the other. In order to obtain very precise correlation at the appropriate scale between the color aspect and the element and mineralogical phase distributions in the slip, combined electron microprobe, x-ray micro spectroscopies and micro diffraction on cross sectional samples were performed. The aim is to discover how potters were able to produce this unique type of terra sigillata and especially this slip showing an intense yellow color. Results show that the yellow component of marbled sigillata was made from a titanium-rich clay preparation. The color is related to the formation of a pseudobrookite (TiFe2O5) phase in the yellow part of the slip, the main characteristics of that structure being considered nowadays as essential for the fabrication of stable yellow ceramic pigments. Its physical properties such as high …
Date: January 31, 2009
Creator: Leon, Yoanna; Sciau, Philippe; Goudeau, Philippe; Tamura, Nobumichi; Webb, Sam & Mehta, Apurva
System: The UNT Digital Library