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Low sample volume part-per billion level ion chromatographic analysis

Description: ADS has developed an ion chromatographic method which enables low part-per-billion levels of analysis while minimizing liquid waste generation. This method incorporates several recent technical improvements in ion chromatographic instrumentation to achieve a ten- fold increase in sensitivity over existing ion chromatographic methods without additional analysis time or sample pre-concentration. This report outlines the method, establishes the precision and accuracy levels, and discusses the applicability of the method to waste minimization and radiation exposure reduction
Date: February 27, 1996
Creator: Ekechukwu, A.A.
Partner: UNT Libraries Government Documents Department

Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996]

Description: Polymer degradation occurs when polymer chains are broken under the influence of thermal, mechanical, or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here we develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of the MWDs. The governing integro-differential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably portray experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of polymer degradation processes.
Date: February 27, 1996
Creator: McCoy, B.J. & Madras, G.
Partner: UNT Libraries Government Documents Department

Improved Evolutionary Hybrids for Flexible Ligand Docking in Autodock

Description: In this paper we evaluate the design of the hybrid evolutionary algorithms (EAs) that are currently used to perform flexible ligand binding in the Autodock docking software. Hybrid EAs incorporate specialized operators that exploit domain-specific features to accelerate an EA's search. We consider hybrid EAs that use an integrated local search operator to reline individuals within each iteration of the search. We evaluate several factors that impact the efficacy of a hybrid EA, and we propose new hybrid EAs that provide more robust convergence to low-energy docking configurations than the methods currently available in Autodock.
Date: January 27, 1999
Creator: Belew, R.K.; Hart, W.E.; Morris, G.M. & Rosin, C.
Partner: UNT Libraries Government Documents Department

Chemical synthesis, characterization and separation studies of functionalized polymeric supports. Final report

Description: Polymer resins with immobilized phosphorus acid ligands have been used to remove metal ions from solutions over wide pH range. These resins offer selective removal of metal ions under acidic conditions through coordination with the phosphoryl oxygen. Use of poly(vinylbenzyl chloride) foams as supports for phosphorus-based ligands is examined in this report. Foams with large pore volumes as supports offer an advantage over gel and macroporous beads in that the increased porosity could lead to increased rates of metal ion complexation, and the larger pore size allows the use of more hydrophobic ligands such as phosphonate esters in metal ion complexations from aqueous solutions. Effects of crosslinking and sulfonation on metal ion complexation are also studied.
Date: October 27, 1994
Creator: Alexandratos, S.D. & Beauvais, R.
Partner: UNT Libraries Government Documents Department

Separable high explosive systems

Description: A number of approaches have been considered regarding the feasibility of separable high explosive systems for possible application in the Super Safe Program (Ambassador). After a very brief and limited investigation we have categorized various systems and given examples. The two basic approaches in the Ambassador program appear to be: Movement of fissionable material, and movement of explosives. Since explosives are our business, we will comment only on the latter approach. Movement of the explosive could entail small amounts of HE, such as for a detonator, booster, or a portion of the main charge.. These possibilities tend to beg the issue of true safety and dispersal. Movement of the entire main charge or of separate non HE components is certainly more desirable. Separable explosive systems are discussed.
Date: October 27, 1971
Creator: Finger, M.
Partner: UNT Libraries Government Documents Department

Progress report on the evaluation of porous cathode for the electrochemical reduction of nitrates and nitrites in liquid wastes

Description: This report describes the experimental and modeling work performed to evaluate porous cathodes for the electrochemical reduction of nitrites in liquid wastes. The experiments were done using the MP{dagger} cell with two different porous cathodes: nickel foam and TySAR{trademark}SB{double_dagger}. The experimental results are compared with each other and to those obtained with a planar nickel cathode. The results show that the ammonia production reaction is the dominant cathodic reaction ({approximately}80% efficiency) for all three electrodes. The temperature range used in this study was 29-37 {circ}C while the catholyte feed was either 0.6M NaNO{sub 2} or 1.9M NaNO{sub 3}, both supported by a 1.33 M NaOH solution. All experiments used a constant current density of 0.25 A/cm{sup 2}. The experimental results suggest that the porous nickel electrode at lower temperatures ({approximately}31{circ}C) is the most efficient of the three electrodes for the reduction of nitrates and nitrites. The porous nickel electrode exhibited the highest conversion of nitrates and nitrites, and the lowest overpotential for a given current density. The partial current fractions at known catholyte concentrations were used to extract the exchange-current densities for the five cathodic reactions. Using these kinetic parameters, dynamic simulations of the four hour experiments were performed. Agreement was found between the model and experimental results for changes in the moles of the nitrate and nitrite and the cell overpotential with time. Future work will determine the effects of temperature and current densities on the exchange-current densities and reaction product distributions. The performance of other porous cathode materials (TySAR{trademark}EP{section}, TySAR{trademark}IM) will also be evaluated.
Date: December 27, 1995
Creator: Hobbs, D.T.; Jha, K.; Weidner, J.W. & White, R.E.
Partner: UNT Libraries Government Documents Department

Enhancement of Equilibrium Shift in Dehydrogenation Reactions Using A Novel Membrane Reactor

Description: Electroless deposition of palladium thin-films on a surface of microporous ceramic substrate has been used to develop a new class of perm-selective inorganic membrane. In our previous two reports, we presented mathematical models to describe transport of hydrogen the palladium-ceramic composite membrane in single-stage permeation cell in cocurrent and countercurrent flow configurations. Analysis shows that the model equations have a singular point. In this report, a method is described how to avoid the singular point in order to solve the model equations numerically. To show the usefulness of the new method, a single-stage gas permeation for a three component system, without chemical reaction under cocurrent flow configuration has been used as an example.
Date: May 27, 1998
Creator: King, Franklin G. & Ilias, Shamsuddin
Partner: UNT Libraries Government Documents Department

Startup and Operation of a Metal Hydride Based Isotope Separation Process

Description: Production scale separation of tritium from other hydrogen isotopes at the Savannah River Site (SRS) in Aiken, SC, has been accomplished by several methods. These methods include thermal diffusion (1957--1986), fractional absorption (1964--1968), and cryogenic distillation (1967-present). Most recently, the Thermal Cycling Absorption Process (TCAP), a metal hydride based hydrogen isotope separation system, began production in the Replacement Tritium Facility (RTF) on April 9, 1994. TCAP has been in development at the Savannah River Technology Center since 1980. The production startup of this semi-continuous gas chromatographic separation process is a significant accomplishment for the Savannah River Site and was achieved after years of design, development, and testing.
Date: February 27, 1995
Creator: Scogin, J. H. & Poore, A. S.
Partner: UNT Libraries Government Documents Department

Active source requirements for assay of sludge drums on the BIR WIT system

Description: The design of the active source for active and passive computed tomography (A&PCT) is critical with respect to accuracy and throughput. The A&PCT active source requirements are highly dependent upon the attenuation properties of the waste matrix within the drum. On of the most highly attenuating waste matrices is sludge. This waste stream will consist of solidified aqueous waste consisting of IDC 001 first stage sludge and IDC 007 wet sludge. Also, the stream consists of solidified organic waste known as code IDC 003 organic setups. We have evaluated the sludge drum data that was previously acquired on the WIT system and have determined that the active source activity must be increased to provide reasonable throughput. The sludge drum that is evaluated here is drum CEPRF11. CEPRF11 is a test drum that was part of the Nondestructive Assay system Capability Evaluation Project (CEP) and contained an actual Rocky Flats waste that is categorized as code 003 solidified organic waste. The full drum was evaluated and found to be somewhat homogenous; therefore, a single slice is arbitrarily chosen to represent the entire drum. Slice number 8 is used and is located approximately at the center of the drum. Figure 1 shows the averaged projections for different energies derived from the active sinogram of slice number 8 from the CEPRF11 drum. This is the average of all the projections of slice 8 taken over 180 degrees with an active integration time of 6 seconds. Figure 2 is also a graph showing the average of all the projections for slice 8; however, the active integration time is 30 seconds.
Date: April 27, 1998
Creator: Roberson, G. P. & Camp, D. C.
Partner: UNT Libraries Government Documents Department

Applications of electrochemically-modulated liquid chromatography (EMLC): Separations of aromatic amino acids and polycyclic aromatic hydrocarbons

Description: The research in this thesis explores the separation capabilities of a new technique termed electrochemically-modulated liquid chromatography (EMLC). The thesis begins with a general introduction section which provides a literature review of this technique as well as a brief background discussion of the two research projects in each of the next two chapters. The two papers which follow investigate the application of EMLC to the separation of a mixture of aromatic amino acids and of a mixture of polycyclic aromatic hydrocarbons (PAHs). The last section presents general conclusions and summarizes the thesis. References are compiled in the reference section of each chapter. The two papers have been removed for separate processing.
Date: March 27, 1998
Creator: Deng, L.
Partner: UNT Libraries Government Documents Department

Remote nuclear screening system for hostile environments

Description: A remote measurement system has been constructed for in situ gamma and beta isotopic characterization of highly radioactive nuclear material in hostile environments. A small collimated, planar CdZnTe detector is used for gamma-ray spectroscopy. Spectral resolution of 2% full width at half maximum at 662 kiloelectronvolts has been obtained remotely using rise time compensation and limited pulse shape discrimination, Isotopc measurement of high-energy beta emitters was accomplished with a ruggedized, deeply depleted, surface barrier silicon dictator. The primary function of the remote nuclear screening system is to provide fast qualitative and quantitative isotopic assessment of high-level radioactive material.
Date: February 27, 1996
Creator: Addleman, R. S.; Beck, M.A.; Blewett, G.R.; Selle, E.R.; McClellan, C.S.; Dodd, D.A. et al.
Partner: UNT Libraries Government Documents Department

Synthesis, scale-up, and characterization of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

Description: We have synthesized 4OOg of the new, insensitive, energetic heterocycle, 2,6-diamino-3,5-dinitropyrazine-l-oxide (LLM-105) with 81% the energy of HMX and excellent thermal stability. The synthesis is a three step reaction sequence from the commercially available starting material, 2,6-dichloropyrazine, with an overall yield of 36%. In this paper we will describe the scale-up of the synthesis of LLM- 105 and report on performance and shock sensitivity experiments performed on this material.
Date: April 27, 1998
Creator: Pagoria, P. F.
Partner: UNT Libraries Government Documents Department

Full image spectral analysis of elemental emissions from an echelle spectrograph

Description: A new algorithm compares the background corrected echelle emission image obtained from reference standards to images of unknowns for quantitative elemental analyses. Wavelength was not used in the calculations but instead pixel position and intensity. The data reduction solution was unique to the particular detector/spectrometer. The approach was found useful for several types of images including ICP, DCP and glow discharge images. The analysis scheme required that the emission pattern of standards and background be held in memory. A dual weighting scheme was used that decreased the importance of pixels in high background areas and enhanced the importance of signals from pixels where the standards had emissions. Threshold values were used to limit the calculations to signals in the linear range of the electronics. Logarithmic weighting, (by taking the square root), was found to work well for weighting pixels from the standards. This assured that minor emissions had some influence on the data fit. In the program the best-fit scalar was determined using simple iterative guess, change and test approaches. The test looked for the minimum least square residual value in the areas of the flagged pixels.
Date: January 27, 2000
Creator: Spencer, W.A.
Partner: UNT Libraries Government Documents Department

In situ hydrothermal oxidative destruction of DNAPLS in a creosote contaminated site

Description: Hydrous Pyrolysis / Oxidation (HPO) is an in situ thermal remediation technology that uses hot, oxygenated groundwater to completely mineralize a wide range of organic pollutants. A field demonstration of HPO was performed at a creosote contaminated site during the summer of 1997. The groundwater was heated by steam injections and oxygen was added by coinjection of compressed air. The remediation was monitored from multiple groundwater monitoring wells. Dissolved organic carbon levels increased in response to steam injections as a result of the enhanced dissolution and mobilization of the creosote into the heated groundwater. Elevated concentrations of partially oxidized organic compounds (i.e. phenols, benzoic acid, fluorenone, anthrone and 9,10- anthracenedione), decreased levels of dissolved oxygen and isotopic shifts in the dissolved inorganic pool were indicators of partial to complete oxidative destruction of the creosote in the heated aquifer as a result of the HPO process.
Date: February 27, 1998
Creator: Leif, R. N., LLNL
Partner: UNT Libraries Government Documents Department

The development of precipitated iron catalysts with improved stability; Final report, September 1987--September 1992

Description: Precipitated iron catalysts are expected to be used in next generation slurry reactors for large-scale production of transportation fuels from synthesis gas. These reactors are expected to operate at higher temperatures and lower H{sub 2}:CO ratios relative to the Sasol Arge reactor (Table 1A). The feasibility of using iron catalysts has been demonstrated under relatively mild Arge-type conditions but not under more severe slurry conditions. Possibly, an improvement in catalytic stability will be needed to make iron catalysts suitable for slurry operation. This program was aimed at identifying the chemical principles governing the deactivation of precipitated iron catalysts during Fischer-Tropsch synthesis and use of these chemical principles in the design of more stable catalysts. A new precipitated Fe catalyst was developed in this program for slurry reactor operation. The new Fe catalyst is predicted to perform slightly below the performance targets for slurry bubble column operation. Stability targets appear to be achievable. This catalyst did not noticeably deactivate during 1,740 hours on-stream. Compared to the selectivity target, an excess of 2% C{sub 1} + C{sub 2} was formed at 265{degrees}C. Based on the initial catalyst inventory in the autoclave, the catalyst seems to be short of the activity target by a factor of 1.8 at 265{degrees}C and 1.3 at 275{degrees}C. However, actual specific activities are likely to be closer to target because of catalyst inventory loss across the filter during the run and because catalytic activities were underestimated at low conversions.
Date: December 27, 1993
Creator: Abrevaya, H.
Partner: UNT Libraries Government Documents Department

Fuel property effects on engine combustion processes. Final report

Description: A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE ) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.
Date: April 27, 1995
Creator: Cernansky, N.P. & Miller, D.L.
Partner: UNT Libraries Government Documents Department