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Simulations of laser-initiated stress waves

Description: We present a study of the short-time scale (< 250 ns) fluid dynamic response of water to a fiber-delivered laser pulse of variable energy and spatial profile. The laser pulse was deposited on a stress confinement time scale. The spatial profile was determined by the fiber core radius r (110 and 500 microns) and the water absorption coefficient {mu}{sub 2} (200 and 50 l/cm). Considering 2D cylindrical symmetry, the combination of fiber radius and absorption coefficient parameters can be characterized as near planar (1{mu}{sub 2} greater than r), symmetric (1/{mu}{sub 2}=r), and side-directed (1/{mu}{sub 2} less than r). The spatial profile study shows how the stress wave various as a function of geometry. For example, relatively small absorption coefficients can result in side-propagating shear and tensile fields.
Date: March 7, 1997
Creator: Maitland, D.J.; Celliers, P.; Amendt, P.; Da Silva, L.; London, R.A.; Matthews, D. et al.
Partner: UNT Libraries Government Documents Department

Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report No. 7, April 1, 1996--June 30, 1996

Description: The objective of this research project is to develop the technology for the production of physically robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry phase synthesis reactor development. The catalysts that are developed shall be suitable for testing in the Advanced Fuels Development Facility at LaPorte, Texas, to produce either low- or high-alpha product distributions. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the ``standard-catalyst`` developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst this is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity and aging characteristics. The research is divided into four major topical areas: (a) catalyst preparation and characterization, (b) product characterization, (c) reactor operations, and (d) data assessment.
Date: August 7, 1996
Creator: Davis, B.H.
Partner: UNT Libraries Government Documents Department

Development of precipitated iron Fischer-Tropsch catalysts. Quarterly report, October 1, 1996--December 31, 1996

Description: The overall contract objectives are to: (1) demonstrate repeatability of performance and preparation procedure of two high activity, high alpha iron Fischer-Tropsch catalysts synthesized at Texas A&M University, (2) seek potential improvements in the catalyst performance through variations in process condition, pretreatment procedures and/or modification in catalyst synthesis, (3) investigate performance of catalysts in a small scale bubble column slurry reactor, and (4) investigate feasibility of producing catalysts on a large scale in collaboration with a catalyst manufacturer. Work during this period included pretreatment effect research and catalyst characterization.
Date: March 7, 1997
Creator: Bukur, D.B.
Partner: UNT Libraries Government Documents Department

Application of mid-infrared spectroscopy to the identification of materials and to the determination of surface coatings

Description: A small user friendly, light-weight, field hardened, computer controlled device for performing infrared spectroscopic analysis, with high sensitivity of trace contamination on surfaces, has recently been defined by Lockheed Martin Energy Systems, Inc. The National Aeronautics and Space Administration at Marshall Space Flight Center, Alabama (NASA/MSFC) initiated a development contract to field a production model of this device with Surface Optics Corporation, San Diego, California in order to certify the sandblasted inner surface of solid rocket motor casings to be free of both hydrocarbon grease and silicone oils at levels approaching 1 milligram per square foot. Through contracts with Lockheed Martin Energy Systems, Inc., the Army acquired a prototype of this instrument, which was used for optimizing the performance with respect to detecting trace organic contamination on sandblasted metal surfaces. That prototype has since been upgraded to incorporate the refinements discovered in its use, and is presently being field tested by the Army at the Corpus Christi Army Depot (CCAD). Referred to as a surface inspection machine-infrared (SIMIR or SOC 400), this device employs a miniature Fourier transform Infrared spectrometer (FTIRS) with very efficient diffuse reflectance optics to provide reflectance spectra of surfaces measured relative to some reference surface. These spectra are capable of yielding qualitative and quantitative chemical information from a host of surfaces that has imminently practical applications in the determination of surface identification, contamination, and degradation. The performance of the SIMIR and its initial applications to surface inspection at CCAD that include sandblasted metal surfaces, as well as, detection of contamination on other metal finishes such as black oxide finished steel.
Date: June 7, 1996
Creator: Powell, G.L.; Engbert, E.G.; Holiday, J. & Velez, J.L.
Partner: UNT Libraries Government Documents Department

Excess Sodium Tetraphenylborate and Intermediates Decomposition Studies

Description: The stability of excess amounts of sodium tetraphenylborate (NaTPB) in the In-Tank Precipitation (ITP) facility depends on a number of variables. Concentration of palladium, initial benzene, and sodium ion as well as temperature provide the best opportunities for controlling the decomposition rate. This study examined the influence of these four variable on the reactivity of palladium-catalyzed sodium tetraphenylborate decomposition. Also, single effects tests investigated the reactivity of simulants with continuous stirring and nitrogen ventilation, with very high benzene concentrations, under washed sodium concentrations, with very high palladium concentrations, and with minimal quantities of excess NaTPB.
Date: December 7, 1998
Creator: Barnes, M.J.
Partner: UNT Libraries Government Documents Department

Tetrahedral-Network Organo-Zincophosphates: Syntheses and Structures of (N(2)C(6)H(14)).Zn(HPO(4))(2).H(2)O, H(3)N(CH(2))(3)NH(3).Zn(2)(HPO(4))(3) and (N(2)C(6)H(14)).Zn(3)(HPO(4))(4)

Description: The solution-mediated syntheses and single crystal structures of (N<sub>2</sub>C<sub>6</sub>H<sub>14</sub>)&middot;Zn(HPO<sub>4</sub>)<sub>2</sub>&middot;H<sub>2</sub>O (I), H<sub>3</sub>N(CH<sub>2</sub>)<sub>3</sub>NH<sub>3</sub>&middot;Zn<sub>2</sub>(HPO<sub>4</sub>)<sub>3</sub> (II), and (N<sub>2</sub>C<sub>6</sub>H<sub>14</sub>)&middot;Zn<sub>3</sub>(HPO<sub>4</sub>)<sub>4</sub> (III) are described. These phases contain vertex-sharing Zn0<sub>4</sub> and HP0<sub>4</sub> tetrahedra, accompanied by doubly- protonated organic cations. Despite their formal chemical relationship, as members of the series of t&middot;Zn<sub>n</sub>(HP0<sub>4</sub>)<sub>n+1</sub> (t= template, n = 1-3), these phases adopt fimdamentally different crystal structures, as one-dimensional, two-dimensional, and three-dimensional Zn0<sub>4</sub>/HP0<sub>4</sub> networks, for I, II, and III respectively. Similarities and differences to some other zinc phosphates are briefly discussed. Crystal data: (N<sub>2</sub>C<sub>6</sub>H<sub>14</sub>)&middot;Zn(HP0<sub>4</sub>)<sub>2</sub>&middot;H<sub>2</sub>0, M<sub>r</sub> = 389.54, monoclinic, space group P2<sub>1</sub>/n (No. 14), a = 9.864 (4) &Aring;, b = 8.679 (4) &Aring;, c = 15.780 (3) &Aring;, &beta; = 106.86 (2)&deg;, V= 1294.2 (8) &Aring;<sup>3</sup>, Z = 4, R(F) = 4.58%, R<sub>W</sub>(F) = 5.28% [1055 reflections with I >3&sigma;(I)]. H<sub>3</sub>N(CH<sub>2</sub>)<sub>3</sub>NH<sub>3</sub>&middot;Zn<sub>2</sub>(HP0<sub>4</sub>)<sub>3</sub>, M<sub>r</sub> = 494.84, monoclinic, space group P2<sub>1</sub>/c (No. 14), a= 8.593 (2)&Aring;, b= 9.602 (2)&Aring;, c= 17.001 (3)&Aring;, &beta;= 93.571 (8)&deg;, V = 1400.0 (5) &Aring;<sup>3</sup>, Z = 4, R(F) = 4.09%, R<sub>W</sub>(F) = 4.81% [2794 reflections with I > 3&sigma; (I)]. (N<sub>2</sub>C<sub>6</sub>H<sub>14</sub>)&middot;Zn<sub>3</sub>(HP0<sub>4</sub>)<sub>4</sub>, M<sub>r</sub>= 694.25, monoclinic, space group P2<sub>1</sub>/n (No. 14), a = 9.535 (2) &Aring;, b = 23.246 (4)&Aring;, c= 9.587 (2)&Aring;, &beta;= 117.74 (2)&deg;, V= 1880.8 (8) &Aring;<sup>3</sup>, Z = 4, R(F) = 3.23%, R<sub>W</sub>(F) = 3.89% [4255 reflections with 1> 3&sigma;(I)].
Date: May 7, 1999
Creator: Chavez, Alejandra V.; Hannooman, Lakshitha; Harrison, William T.A. & Nenoff, Tina M.
Partner: UNT Libraries Government Documents Department

Syntheses and Structures of the Open-Framework Phases (CH(3)NH(3))(3).Zn(4)O(AsO(4))(3) and (CH(3)NH(3))(3).Zn(4)O(PO(4))(3) Related to the M(3)Zn(4)O(XO(4)(3).nH(2)O Family

Description: The solution-mediated syntheses and single crystal structures of (CH<sub>3</sub>NH<sub>3</sub>)<sub>3</sub>&middot;Zn<sub>4</sub>0(AsO<sub>4</sub>)<sub>3</sub> and (CH<sub>3</sub>NH<sub>3</sub>)<sub>3</sub>&middot;Zn<sub>4</sub>O(P0<sub>4</sub>)<sub>3</sub> are reported. These compounds are built up from vertex-sharing three-dimensional Zn0<sub>4</sub> + AsO<sub>4</sub>/P0<sub>4</sub> tetrahedral frameworks encapsulating methylammonium cations in three-dimensional channel systems. These phases are closely related to the zeolite- like M<sub>3</sub>Zn<sub>4</sub>O(XO<sub>4</sub>)<sub>3</sub>&middot;nH<sub>2</sub>O family of phases. Crystal data for (CH<sub>3</sub>NH<sub>3</sub>)<sub>3</sub>&middot;Zn<sub>4</sub>0(AsO<sub>4</sub>)<sub>3</sub>, M, = 790.47, monoclinic, space group P2<sub>1</sub> (No. 4), a = 7.814 (3)&Aring;, b = 15.498 (6)&Aring;, c = 7.815 (3) &Aring;, {beta} = 92.91 (2)0, V = 945.1 (9) &Aring;<sup>3</sup>, Z = 2, R(F) = 3.01%, R<sub>W</sub>(F) = 3.98% (2301 reflections, 236 parameters). Crystal data for (CH<sub>3</sub>NH<sub>3</sub>)<sub>3</sub>&middot;Zn<sub>4</sub>0(P0<sub>4</sub>)<sub>3</sub>: M, = 658.63, monoclinic, space group P2<sub>1</sub> (No. 4), a = 7.6569 (5) &Aring;, b = 15.241 (1)&Aring;, c= 7.6589 (5) &Aring;, {beta} = 92.740 (1)0, V= 892.7 (5) &Aring;<sup>3</sup>, Z = 2, R(F)= 8.07%, R<sub>W</sub>(F)= 9.60% (2694 reflections, 106 parameters).
Date: May 7, 1999
Creator: Chavez, Alejandra V.; Harrison, William T.A.; Nenoff, Tina M. & Phillips, Mark L.F.
Partner: UNT Libraries Government Documents Department

Analytical electron microscopy of bimetallic catalysts. Final report

Description: The report summarizes the accomplishments, publications, and reception of this program in the catalyst and microanalytical communities. Initially the research covered a wide range of catalysts, but later in the program, the author prepared and optimized a highly active catalyst for low-temperature NO abatement in fossil fuel power plants. During the course of the program, several innovations in microanalytical instrumentation and technique were developed specifically for analysis of catalytic nanoparticles. New designs for improved nanoparticle elemental sensitivity were proposed and accepted by the manufacture of Lehigh`s new VG /HB-603 analytical electron microscope. New tests for assessing elemental sensitivity have been devised and used to encourage the manufacturer to build the most sensitive analytical electron microscope in the world. Accomplishments summarized for the 1986--1990 period include: Quantitative measurements of noble metal distributions in alumina monoliths; Direct elemental imaging of small metal particles poisoned by sulfur: Analysis of surface species on Co/La/alumina catalyst; and Development of analytical electron microscopy methods. Accomplishments for the 1991--1993 period include: Catalytic testing facility for the electron microscopy lab; New scheme for immobilization of surface species for AEM analysis; and New method for electron probe microanalysis of porous materials. Accomplishments for the 1994--1998 period were: successful low-temperature NO reduction using a new Pt-Rh alloy catalyst; Composition size diagrams to identify active catalysts; Observation of phase separation in Pt-Rh at 300 C; Observation of surface segregation in Pt-rich nanoparticles; CO oxidation over Pt-Rh catalyst; Sulfur poisoning characteristics; Commercial development of NO catalysts; and Analysis of sub-1-nm particles in Pt-Re reforming catalysts.
Date: September 7, 1998
Creator: Lyman, C.E.
Partner: UNT Libraries Government Documents Department

Synthesis, Characterization and Ion Exchange of New Na/Nb/M(4+)/O/H(2)O(M=Ti,Zr) Phases

Description: Due to the vast diversity of chemical media in which metal separations are executed, a wide range of ion separation materials are employed. This results in an ongoing effort to discover new phases with novel ion exchange properties. We present here the synthesis of a novel class of thermally and chemically stable microporous, niobate-based materials. Ion exchange studies show these new phases are highly selective for Sr<sup>2+</sup> and other bivalent metals.
Date: May 7, 1999
Creator: Nenoff, Tina M. & Nyman, May
Partner: UNT Libraries Government Documents Department

Pathway and kinetic analysis on the iso-propyl radical + O{sub 2} reaction system

Description: We analyze the isopropyl + 02 reaction system using thermochemical Transition State Theory (TST), molecular thermodynamic properties, analysis (quantum RRK) for k(E) and modified strong collision analyze Cyclic transition states for both hydrogen transfer and concerted propylene from isopropylperoxy are calculated using semi-empirical theory in addition to transition states for H02 elimination from hydroperoxy-isopropyl. Computed rate constants are compared to constant measurements of for isopropyl + H02.
Date: April 7, 1997
Creator: Bozzelli, J. W. & Pitz, W. J.
Partner: UNT Libraries Government Documents Department

"A Novel Synthesis of Zeolite W..."

Description: Zeolite W has been synthesized using organometallic silicon and aluminum precursors in two hydrothermal systems: organocation containing and organocation-free. The reaction using the organocation yielded a fully crystalline, relatively uniform crystal size product, with no organic molecules occluded in the pores. In contrast, the product obtained from an identical reaction, except for the absence of the organocation, contained amorphous as well as crystalline material and the crystalline phase showed a large diversity of both crystal size and morphology. The use of organometallic precursors, either with or without an organocation, allows for the crystallization of the MER framework at much lower 0H/Si02 and (K+ Na - Al)/Si ratios than is typical of inorganic systems. The reaction products were characterized by XRD, SEM, EDS, and thermal analyses.
Date: May 7, 1999
Creator: Nenoff, Tina M. & Thoma, Steven G.
Partner: UNT Libraries Government Documents Department

Synthesis, characterization and application of electrode materials

Description: It has been known that significant advances in electrochemistry really depend on improvements in the sensitivity, selectivity, convenience, and/or economy of working electrodes, especially through the development of new working electrode materials. The advancement of solid state chemistry and materials science makes it possible to provide the materials which may be required as satisfactory electrode materials. The combination of solid state techniques with electrochemistry expands the applications of solid state materials and leads to the improvement of electrocatalysis. The study of Ru-Ti{sub 4}O{sub 7} and Pt-Ti{sub 4}O{sub 7} microelectrode arrays as introduced in paper 1 and paper 4, respectively, focuses on their synthesis and characterization. The synthesis is described by high temperature techniques for Ru or Pt microelectrode arrays within a conductive Ti{sub 4}O{sub 7} ceramic matrix. The characterization is based on the data obtained by x-ray diffractometry, scanning electron microscopy, voltammetry and amperometry. These microelectrode arrays show significant enhancement in current densities in comparison to solid Ru and Pt electrodes. Electrocatalysis at pyrochlore oxide Bi{sub 2}Ru{sub 2}O{sub 7.3} and Bi{sub 2}Ir{sub 2}O{sub 7} electrodes are described in paper 2 and paper 3, respectively. Details are reported for the synthesis and characterization of composite Bi{sub 2}Ru{sub 2}O{sub 7.3} electrodes. Voltammetric data are examined for evidence that oxidation can occur with transfer of oxygen to the oxidation products in the potential region corresponding to anodic discharge of H{sub 2}O with simultaneous evolution of O{sub 2}. Paper 3 includes electrocatalytic activities of composite Bi{sub 2}Ir{sub 2}O{sub 7} disk electrodes for the oxidation of I{sup -} and the reduction of IO{sub 3}{sup -}.
Date: July 7, 1995
Creator: He, L.
Partner: UNT Libraries Government Documents Department

Preliminary report on SG126 Task 3: {sup 129}I interlaboratory comparison

Description: An interlaboratory comparison exercise for {sup 129}I has been organized and conducted. A total of seven laboratories participated in the exercise to either a full or limited extent. In the comparison, a suite of 11 samples was used. This suite of standards contained both synthetic `standard type` materials (i.e., AgI) and environmental materials. The isotopic {sup 129}I/{sup 127}I ratio of the samples varied from 10{sup -8} to 10{sup -14}. Results of the comparison are presented.
Date: March 7, 1996
Creator: Roberts, M.L.; Caffee, M.W. & Proctor, I.D.
Partner: UNT Libraries Government Documents Department

Separation, Concentration, and Immobilization of Technetium and Iodine from Alkaline Supernate Waste

Description: Development of remediation technologies for the characterization, retrieval, treatment, concentration, and final disposal of radioactive and chemical tank waste stored within the Department of Energy (DOE) complex represents an enormous scientific and technological challenge. A combined total of over 90 million gallons of high-level waste (HLW) and low-level waste (LLW) are stored in 335 underground storage tanks at four different DOE sites. Roughly 98% of this waste is highly alkaline in nature and contains high concentrations of nitrate and nitrite salts along with lesser concentrations of other salts. The primary waste forms are sludge, saltcake, and liquid supernatant with the bulk of the radioactivity contained in the sludge, making it the largest source of HLW. The saltcake (liquid waste with most of the water removed) and liquid supernatant consist mainly of sodium nitrate and sodium hydroxide salts. The main radioactive constituent in the alkaline supernatant is cesium-137, but strontium-90, technetium-99, and transuranic nuclides are also present in varying concentrations. Reduction of the radioactivity below Nuclear Regulatory Commission (NRC) limits would allow the bulk of the waste to be disposed of as LLW. Because of the long half-life of technetium-99 (2.1 x 10 5 y) and the mobility of the pertechnetate ion (TcO 4 - ) in the environment, it is expected that technetium will have to be removed from the Hanford wastes prior to disposal as LLW. Also, for some of the wastes, some level of technetium removal will be required to meet LLW criteria for radioactive content. Therefore, DOE has identified a need to develop technologies for the separation and concentration of technetium-99 from LLW streams. Eichrom has responded to this DOE-identified need by demonstrating a complete flowsheet for the separation, concentration, and immobilization of technetium (and iodine) from alkaline supernatant waste.
Date: December 7, 1998
Creator: Harvey, James & Gula, Michael
Partner: UNT Libraries Government Documents Department

Evaluation of alternative chemical additives for high-level waste vitrification feed preparation processing

Description: During the development of the feed processing flowsheet for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS), research had shown that use of formic acid (HCOOH) could accomplish several processing objectives with one chemical addition. These objectives included the decomposition of tetraphenylborate, chemical reduction of mercury, production of acceptable rheological properties in the feed slurry, and controlling the oxidation state of the glass melt pool. However, the DEPF research had not shown that some vitrification slurry feeds had a tendency to evolve hydrogen (H{sub 2}) and ammonia (NH{sub 3}) as the result of catalytic decomposition of CHOOH with noble metals (rhodium, ruthenium, palladium) in the feed. Testing conducted at Pacific Northwest Laboratory and later at the Savannah River Technical Center showed that the H{sub 2} and NH{sub 3} could evolve at appreciable rates and quantities. The explosive nature of H{sub 2} and NH{sub 3} (as ammonium nitrate) warranted significant mitigation control and redesign of both facilities. At the time the explosive gas evolution was discovered, the DWPF was already under construction and an immediate hardware fix in tandem with flowsheet changes was necessary. However, the Hanford Waste Vitrification Plant (HWVP) was in the design phase and could afford to take time to investigate flowsheet manipulations that could solve the problem, rather than a hardware fix. Thus, the HWVP began to investigate alternatives to using HCOOH in the vitrification process. This document describes the selection, evaluation criteria, and strategy used to evaluate the performance of the alternative chemical additives to CHOOH. The status of the evaluation is also discussed.
Date: June 7, 1995
Creator: Seymour, R.G.
Partner: UNT Libraries Government Documents Department

Matrix effects in inductively coupled plasma mass spectrometry

Description: The inductively coupled plasma is an electrodeless discharge in a gas (usually Ar) at atmospheric pressure. Radio frequency energy generated by a RF power source is inductively coupled to the plasma gas through a water cooled load coil. In ICP-MS the {open_quotes}Fassel{close_quotes} TAX quartz torch commonly used in emission is mounted horizontally. The sample aerosol is introduced into the central flow, where the gas kinetic temperature is about 5000 K. The aerosol is vaporized, atomized, excited and ionized in the plasma, and the ions are subsequently extracted through two metal apertures (sampler and skimmer) into the mass spectrometer. In ICP-MS, the matrix effects, or non-spectroscopic interferences, can be defined as the type of interferences caused by dissolved concomitant salt ions in the solution. Matrix effects can be divided into two categories: (1) signal drift due to the deposition of solids on the sampling apertures; and/or (2) signal suppression or enhancement by the presence of the dissolved salts. The first category is now reasonably understood. The dissolved salts, especially refractory oxides, tend to deposit on the cool tip of the sampling cone. The clogging of the orifices reduces the ion flow into the ICP-MS, lowers the pressure in the first stage of ICP-MS, and enhances the level of metal oxide ions. Because the extent of the clogging increases with the time, the signal drifts down. Even at the very early stage of the development of ICP-MS, matrix effects had been observed. Houk et al. found out that the ICP-MS was not tolerant to solutions containing significant amounts of dissolved solids.
Date: July 7, 1995
Creator: Chen, Xiaoshan
Partner: UNT Libraries Government Documents Department

A systematic study of actinide production from the interactions of heavy ions with sup 248 Cm

Description: Production cross sections for heavy actinides produced from the interactions of {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca ions with {sup 248}Cm were measured at energies ranging from 0.98 to 1.35 X Coulomb barrier. The recoiling reaction products were collected in copper or gold catcher foils located near the {sup 248}Cm target. Separate fractions of Bk, Cf, Es, Fm, and Md were obtained from a radiochemical separation procedure. For the {sup 12}C system, a He/KCl jet was used to transport the recoiling No activities of interest to a rotating wheel system. The isotopic distributions of the actinide products were found to be essentially symmetric about the maximum with full-widths-at-half-maximum of approximately 2.5 mass units. Isotopic distributions of the {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca systems were found to be very similar to the {sup 40,48}Ca systems studied previously. The maxima of the isotopic distributions generally occurred for those reaction channels which involved the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy was a positive quantity. Additionally, the maxima of the excitation functions occurred at those projectile energies which were consistent with the calculated reaction barriers based upon a binary reaction mechanism. The experimental data from the four systems investigated were compared to several models of heavy ion interactions including a damped reaction mechanism, compound nucleus formation and subsequent particle evaporation, and classical partial wave calculations for binary systems.
Date: September 7, 1990
Creator: Leyba, J.D.
Partner: UNT Libraries Government Documents Department