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Substituent Effects on Diazeniumdiolate Anions: an AB Initio and DFT Study

Description: Nitroglycerin and isoamyl nitrate have been used as nitrovasodilators since the nineteeth century. However, not until recently has it been known that these compounds were useful since they promoted the release of NO in the body. More recently, a new class of drugs, NO donors, has been developed. These include S-nitrosothiols (RSNO), sydnonimines, and nucleophilic NO adducts.
Date: December 1997
Creator: GarcĂ­a, Samuel A. (Samuel Anthony)
Partner: UNT Libraries

Kinetic study of the reactions of oxygen atoms with nitric oxide and silane

Description: The rate constant for the reactions of oxygen atoms with nitric oxide and silane were determined using a discharge flow apparatus. A microwave discharge through O2N2 and Ar was used to produce oxygen atoms. The rate constant for the reaction O + NO + Ar was determined to be (7.0+0.4) x 10^32 cm^6 s^-1 and is in good agreement with previous measurements.
Date: August 1992
Creator: Taylor, Craig A. (Craig Allan)
Partner: UNT Libraries

The Effects of Nitrogen on the Interface State Density Near the Conduction Band Edge in 4H and 6H-SiC

Description: Results are reported for the passivation of interface states near the conduction band edge in SiO{sub 2}/SiC MOS capacitors using post-oxidation anneals in nitric oxide, ammonia and forming gas (N{sub 2}5%H{sub 2}). Anneals in nitric oxide and ammonia reduce the interface state density significantly for 4H-SiC, while forming gas anneals are largely ineffective. Results suggest that interface states in SiO{sub 2}/SiC and SiO{sub 2}/SiC have different origins, and a model is described for interface state passivation by nitrogen in the SiO{sub 2}/SiC system. The peak inversion channel mobility measured for lateral 4H-SiC MOSFETs increases following NO passivation.
Date: June 12, 2000
Creator: Chung, G.Y.; Tin, C.C.; Isaacs-Smith, T.; Williams, J.R.; McDonald, K.; DiVentra, M. et al.
Partner: UNT Libraries Government Documents Department

Vibrational structure and partial rates of resonant Auger decay ofthe N 1s ->2pi core excitations in nitric oxide

Description: High-resolution resonant Auger electron spectra of NO measured in the vicinity of the N 1s {yields} 2{pi} core excitations are presented. The open shell electronic configuration of the molecule results in four excited electronic states, three of which are populated in the photoabsorption spectrum, {sup 2}{Delta}, {sup 2}{Sigma}{sup -} and {sup 2}{Sigma}{sup +}. Electron emission spectra obtained at different vibrational levels of the three N 1s core-excited states of NO are reported. Recently reported ab initio calculations [J. Chem. Phys. 106, 4038(1997)] are used to generate theoretical spectra for comparison with the experimental results taking lifetime vibration interference and Auger resonant Raman effects into account. Very good agreement is found for the lowest energy X {sup 1}{Sigma}{sup +} final ionic state. Spectra of the higher energy final ionic states are decomposed into contributions from the different 5{sigma}{sup -1}2{pi}{sup 1} and 1{pi}{sup -1}2{pi}{sup 1} configurations for comparison of the calculated and experimental partial Auger decay rates. A revised value for the adiabatic ionization energy of the {sup 1}{Delta} ionic state results from the deconvolution.
Date: July 6, 2000
Creator: Kukk, Edwin; Snell, Gyorgy; Bozek, John D.; Cheng, Wei-T. & Berrah, N.
Partner: UNT Libraries Government Documents Department

Final technical report for award NO. DE-FG02-95ER20206

Description: ABSTRACT Initial work focused on the regulation of nitrite reductase, the defining reaction of denitrification as well as nitric oxide (NO) reductase. Expression of the genes encoding both proteins was controlled by NnrR. This regulator was shown to be responsive to NO. More recent work has shown NnrR function is also likely inhibited by oxygen. Therefore, it is this protein that sets the oxygen level at which nitrate respiration takes over from aerobic respiration. The gene encoding NO reductase appears to only require NnrR for expression. Expression of the gene encoding nitrite reductase is more complex. In addition to NnrR, a two component sensor regulator complex termed PrrA and PrrB is also required for expression. These proteins are global regulators and serve to link denitrification with other bioenergetic processes in the cell. They also provide an additional layer of oxygen dependent regulation. The sequencing of the R. sphaeroides 2.4.3 genome allowed us to identify several other genes regulated by NnrR. Surprisingly, most of the genes were not essential for denitrification. Their high level of conservation in related denitrifiers suggests they do provide a selectable benefit to the bacterium, however. We also examined the role of nitrate reductase in contributing to denitrification in R. sphaeroides. Strain 2.4.3 is unusual in having two distinct, but related clusters of genes encoding nitrate reductase. One of these genes clusters is expressed under high oxygen conditions but is repressed, likely by PrrB-PrrA, under low oxygen conditions. The other cluster is expressed only under low oxygen conditions. This cluster expresses the nitrate reductase used during denitrification. The high oxygen expressed cluster encodes a protein used for redox homeostasis. Surprisingly, both clusters are fully expressed even in the absence of nitrate. During the course of this work we found that the type strain of R. sphaeroides, 2.4.1, ...
Date: February 23, 2010
Creator: Shapleigh, James P.
Partner: UNT Libraries Government Documents Department

Scalable Analysis of Distributed Workflow Traces

Description: Bacterial response to nitric oxide (NO) is of major importance since NO is an obligatory intermediate of the nitrogen cycle. Transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is Large-scale workflows are becoming increasingly important in both the scientific research and business domains. Science and commerce have both experienced an explosion in the sheer amount of data that must be analyzed. An important tool for analyzing these huge datasets is a compute cluster of hundreds or thousands of machines. However, debugging and tuning clusters requires specialized tools. Current cluster performance tools are more oriented towards tightly coupled parallel applications. We describe how the NetLogger Toolkit methodology is more appropriate for this class of cluster computing, and describe our new automatic work flow anomaly detection component. We also describe how this methodology is being used in the Nearby Supernova Factory (SN factory) project at Lawrence Berkeley National Laboratory.
Date: June 1, 2005
Creator: Gunter, Daniel K.; Tierney, Brian L. & Bailey, Stephen J.
Partner: UNT Libraries Government Documents Department

Kinetic studies of competitive adsorption processes related to automobile catalytic converters

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this project was to study the microscopic details for the adsorption of CO, NO, and O{sub 2} on transition metal surfaces under conditions resembling those present in automobile catalytic converters. Initial sticking coefficients were measured as a function of temperature on transition metal single crystals by using a method originally developed by King and Wells. These measurements were performed under conditions emulating those typical of competitive adsorption, namely, where the substrate is exposed to a mixture of two or more gases simultaneously, or where one molecule is adsorbed on the surface prior to exposure to the second gas. The experimental results were then analyzed by using Monte Carlo computer simulation algorithm in an attempt to better understand the relevant aspects of the adsorption process.
Date: December 31, 1998
Creator: Zaera, F. & Paffett, M.T.
Partner: UNT Libraries Government Documents Department


Description: In the last annual reports, we reported Cu-exchanged pillared clays as superior selective catalytic reduction (SCR) catalysts. During the past year we explored the possibilities with MCM-41, a new class of molecular sieve. In this report, Rh exchanged Al-MCM-41 is studied for the SCR of NO by C{sub 3}H{sub 6} in the presence of excess oxygen. It shows a high activity in converting NO to N{sub 2} and N{sub 2}O at low temperatures. In situ FT-IR studies indicate that Rh-NO{sup +} species (1910-1898 cm{sup {minus}1}) is formed on the Rh-Al-MCM-41 catalyst in flowing NO/He, NO+O{sub 2}/He and NO+C{sub 3}H{sub 6}+O{sub 2}/He at 100-350 C. This species is quite active in reacting with propylene and/or propylene adspecies (e.g., {pi}-C{sub 3}H{sub 5}, polyene, etc.) at 250 C in the presence/absence of oxygen, leading to the formation of the isocyanate species (Rh-NCO, at 2174 cm{sup {minus}1}), CO and CO{sub 2}. Rh-NCO is also detected under reaction conditions. A possible reaction pathway for reduction of NO by C{sub 3}H{sub 6} is proposed. In the SCR reaction, Rh-NO{sup +} and propylene adspecies react to generate the Rh-NCO species, then Rh-NCO reacts with O{sub 2}, NO and NO{sub 2} to produce N{sub 2}, N{sub 2}O and CO{sub 2}. Rh-NO{sup +} and Rh-NCO species are two main intermediates for the SCR reaction on Rh-Al-MCM-41 catalyst.
Date: March 31, 1999
Creator: Yang, R. T. & Long, R.Q.
Partner: UNT Libraries Government Documents Department


Description: A flow trough type catalytic reactor system was adequately modified for NO related catalytic and adsorption measurements, including the on-line connection of a digital chemiluminescent NO-NO{sub x} analyzer to the reactor outlet system. Moreover, we have largely completed the installation of an FTIR coupled catalytic system containing a HTEC cell for high temperature DRIFT studies. Three different barium cuprate samples, Ba{sub 2}CuO{sub 3}, BaCuO{sub 2}, and Ba{sub 2}Cu{sub 3}O{sub 5} were synthesized and characterized by powder XRD for catalytic tests. Prior to catalytic studies over these cuprates, a new, liquid indium based supported molten metal catalyst (In-SMMC) was tested in the reduction of NO by various reductants. In the presence of excess O{sub 2} and H{sub 2}O, the In-SMMC proved to be more active for the selective catalytic reduction (SCR) of NO to N{sub 2} by ethanol than most other catalysts. Using C{sub 1}-C{sub 3} alcohols as reductants, self sustained periodic oscillations observed in the NO{sub x} concentrations of reactor effluents indicated the first time that radical intermediates can be involved in the SCR of NO by alcohols. Further, In-SMMC is the only effective and water tolerant SCR catalyst reported thus far which contains SiO{sub 2} support. Thus, this novel catalyst opens up a promising new alternative for developing an effective and durable catalyst for NO{sub x} abatement in stack emission.
Date: April 30, 1998
Partner: UNT Libraries Government Documents Department

Nitric Oxide in Astrocyte-Neuron Signaling

Description: Astrocytes, a subtype of glial cell, have recently been shown to exhibit Ca{sup 2+} elevations in response to neurotransmitters. A Ca{sup 2+} elevation can propagate to adjacent astrocytes as a Ca{sup 2+} wave, which allows an astrocyte to communicate with its neighbors. Additionally, glutamate can be released from astrocytes via a Ca{sup 2+}-dependent mechanism, thus modulating neuronal activity and synaptic transmission. In this dissertation, the author investigated the roles of another endogenous signal, nitric oxide (NO), in astrocyte-neuron signaling. First the author tested if NO is generated during astrocytic Ca{sup 2+} signaling by imaging NO in purified murine cortical astrocyte cultures. Physiological concentrations of a natural messenger, ATP, caused a Ca{sup 2+}-dependent NO production. To test the roles of NO in astrocytic Ca{sup 2+} signaling, the author applied NO to astrocyte cultures via addition of a NO donor, S-nitrosol-N-acetylpenicillamine (SNAP). NO induced an influx of external Ca{sup 2+}, possibly through store-operated Ca{sup 2+} channels. The NO-induced Ca{sup 2+} signaling is cGMP-independent since 8-Br-cGMP, an agonistic analog of cGMP, did not induce a detectable Ca{sup 2+} change. The consequence of this NO-induced Ca{sup 2+} influx was assessed by simultaneously monitoring of cytosolic and internal store Ca{sup 2+} using fluorescent Ca{sup 2+} indicators x-rhod-1 and mag-fluo-4. Blockage of NO signaling with the NO scavenger PTIO significantly reduced the refilling percentage of internal stores following ATP-induced Ca{sup 2+} release, suggesting that NO modulates internal store refilling. Furthermore, locally photo-release of NO to a single astrocyte led to a Ca{sup 2+} elevation in the stimulated astrocyte and a subsequent Ca{sup 2+} wave to neighbors. Finally, the author tested the role of NO inglutamate-mediated astrocyte-neuron signaling by recording the astrocyte-evoked glutamate-dependent neuronal slow inward current (SIC). Although NO is not required for the SIC,PTIO reduced SIC amplitude, suggesting that NO modulates glutamate release from astrocytes ...
Date: June 27, 2002
Creator: Li, Nianzhen
Partner: UNT Libraries Government Documents Department

Final report pulsed plasma processing of effluent pollutants and hazardous chemicals

Description: The electrical discharge techniques, called non-thermal, utilize high voltage breakdown of gases using short pulses of one to a few hundred nanoseconds. These short pulses between metal electrodes generate energetic electrons without appreciable thermal heating of the gas. The energetic electrons collide with gas molecules to form radicals. The radicals then react with pollutants to form harmless compounds. Our non-thermal experimental device used a wire in a pipe geometry. The wire was driven by a 40 kilovolt pulse 100 nanoseconds long. Gas was circulated in a loop through the pipe geometry in a closed system. This system permitted the introduction of various gas combinations prior to testing. The recirculated gas was heated to determine the effect on the electrical discharge, and chemical reactions. Additives were introduced to improve the efficiency (defined as energy input per unit molecule destroyed). The efficient was found to be the most important parameter in that the experiments generally required high energy inputs. However, we were able to significantly improve the efficiency of NO removal by the addition of hydrocarbons, nitric oxide has been removed with an energy cost of 15 ev per NO molecule. We believe the hydrocarbon additive serves by recycling the hydroxyl radicals during the oxidation of NO. The implementation of this process will depend largely on how much additives, electrical power consumption, and final NO{sub x} concentration are acceptable for a particular application.
Date: August 18, 1994
Creator: Vogtlin, G.; Bardsley, N.; Penetrante, B. & Warman, H.
Partner: UNT Libraries Government Documents Department

Evaluation of Rocket Research Company's Plasma Torch for NOx Reduction Studies CRADA PC93-001, Final Report

Description: Combustion and Environmental Research Facility (CERF) formerly known as The Fuel Evaluation Facility was used from March 29 to April 17, 1993 for the sole purpose of evaluating the Rocket Research (RR) plasma torch and testing its effectiveness in reducing NO{sub x} emissions from coal flames. Two spare facility convective sections were modified to accept the torch and to allow for effective mixing in the convective section chambers. The torch was placed into the fourth convective section and a 1-inch fused silica bluff body was placed immediately upstream of the torch to further enhance the mixing at the torch injection location. The gases anticipated for use during testing included ammonia (NH{sub 3}) , hydrogen (H{sub 2}) , carbon monoxide (CO), and methane (CH{sub 4}). Ammonia and hydrogen were planned as the gases which would be introduced through the torch directly while CO and CH{sub 4} would be used only in the torch secondary injection ring. The intent was to minimize any potential fouling problems with the carbon containing gases. Actual test conditions did not allow evaluation of the CO or the CH{sub 4} due to continued intermittent operation of the Rocket Research plasma torch. The torch had not been previously tested under conditions similar to the high temperature condition of the CERF and consequently it was found that the torch would not operate effectively under the test conditions. The torch using NH{sub 3} and H{sub 2} as primary and secondary gases has evaluated for short periods of time.
Date: January 1, 1999
Partner: UNT Libraries Government Documents Department

Effect of Electrode Composition and Microstructure on Impedancemetric Nitric Oxide Sensors based on YSZ Electrolyte

Description: The role of metal (Au, Pt, and Ag) electrodes in YSZ electrolyte-based impedancemetric nitric oxide (NO) sensors is investigated using impedance spectroscopy and equivalent circuit analysis. The test cell consists of a rectangular block of porous YSZ with two metal wire loop electrodes, both exposed to the same atmosphere. Of the electrode materials, only Au was sensitive to changes in NO concentration. The impedance behavior of porous Au electrodes in a slightly different configuration was compared with dense Au electrodes and was also insensitive to NO. Ag showed no sensitivity to either O{sub 2} or NO, and the measured impedances occurred at frequencies > 10 kHz, which are typically associated with ionic conduction in YSZ. Pt and porous Au showed sensitivity to O{sub 2}, which was quantified using power-law exponents that suggest electrochemical rate-determining mechanisms occurring at the triple phase boundary. The behavior of the dense Au suggests different rate-determining processes (e.g., diffusion or adsorption) for the O{sub 2} reaction. Although the exact mechanism is not determined, the composition and microstructure of the metal electrode seem to alter the rate-limiting step of the interfering O{sub 2} reaction. Impedance behavior of the O{sub 2} reaction that is limited by processes occurring away from the triple phase boundary may be crucial for impedancemetric NO sensing.
Date: April 2, 2007
Creator: Woo, L Y; Martin, L P; Glass, R S; Wang, W; Jung, S; Gorte, R J et al.
Partner: UNT Libraries Government Documents Department

The use of rice hulls for sustainable control of NOx emissions in deep space missions

Description: The use of the activated carbon produced from rice hulls to control NOx emissions for the future deep space missions has been demonstrated. The optimal carbonization temperature range was found to be between 600 C and 750 C. The burnoff of 61.8% was found at 700 C in pyrolysis and 750 C in activation. The BET surface area of the activated carbon from rice hulls was determined to be 172 m{sup 2}/g when prepared at 700 C. The presence of oxygen in flue gas is essential for effective adsorption of NO by the activated carbon. On the contrary, water vapor inhibits the adsorption efficiency of NO. Consequently, water vapor in flue gas should be removed by drying agents before adsorption to ensure high NO adsorption efficiency. All of NO in the flue gas was removed for more than one and a half hours when 10% oxygen was present and using a ratio of the carbon weight to the flue gas flow rate (W/F) of 15.4 g-min/L. The reduction of the adsorbed NO to form N{sub 2} can be effectively accomplished under anaerobic conditions at 550 C. For NO saturated activated carbon, the loss of carbon mass was determined to be about 0.16% of the activated carbon per cycle of regeneration. The reduction of the adsorbed NO also regenerates the activated carbon. The regenerated activated carbon exhibits improved NO adsorption efficiency.
Date: December 21, 2001
Creator: Xu, X.H.; Shi, Y.; Chang, S.G.; Fisher, J.W.; Pisharody, S.; Moran, M.J. et al.
Partner: UNT Libraries Government Documents Department

Using hydroponic biomass to regulate NOx emissions in long range space travel

Description: The incineration of wastes is one of the most promising reclamation technologies being developed for life support in long range space travel. However, incineration in a closed environment will build up hazardous NOx if not regulated. A technology that can remove NOx under microgravity conditions without the need of expendables is required. Activated carbon prepared from inedible wheat straw and sweet potato stalk that were grown under hydroponic conditions has been demonstrated to be able to adsorb NO and reduce it to N{sub 2}. The high mineral content in the activated carbon prepared from hydroponic biomass prohibits high surface area production and results in inferior NO adsorption capacity. The removal of mineral from the carbon circumvents the aforementioned negative effect. The optimal production conditions to obtain maximum yield and surface area for the activated carbon have been determined. A parametric study on the NO removal efficiency by the activated carbon has been done. The presence of oxygen in flue gas is essential for effective adsorption of NO by the activated carbon. On the contrary, water vapor inhibits the adsorption efficiency of NO. The NO adsorption capacity and the duration before it exceeds the Space Maximum Allowable Concentration were determined. After the adsorption of NO, the activated carbon can be regenerated for reuse by heating the carbon bed under anaerobic conditions to above 500 C, when the adsorbed NO is reduced to N{sub 2}. The regenerated activated carbon exhibits improved NO adsorption efficiency. However, regeneration had burned off a small percentage of the activated carbon.
Date: February 1, 2002
Creator: Xu, X.H.; Shi, Y.; Chang, S.G.; Fisher, J.; Pisharody, S.; Moran, M. et al.
Partner: UNT Libraries Government Documents Department


Description: An all-solid-state continuous-wave (cw) laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule has been developed and demonstrated. For the NO sensor, 250 nW of tunable cw ultraviolet radiation is produced by sum-frequency-mixing of 532-nm radiation from a diode-pumped Nd:YAG laser and tunable 395-nm radiation from an external cavity diode laser (ECDL). The sum-frequency-mixing process occurs in a beta-barium borate crystal. The nitric oxide absorption measurements are performed by tuning the ECDL and scanning the sum-frequency-mixed radiation over strong nitric oxide absorption lines near 226 nm. In Year 1 of the research, the nitric oxide sensor was used for measurements in the exhaust of a coal-fired laboratory combustion facility. The Texas A&M University boiler burner facility is a 30 kW (100,000 Btu/hr) downward-fired furnace with a steel shell encasing ceramic insulation. Measurements of nitric oxide concentration in the exhaust stream were performed after modification of the facility for laser based NOx diagnostics. The diode-laser-based ultraviolet absorption measurements were successful even when the beam was severely attenuated by particulate in the exhaust stream and window fouling. Single-laser-sweep measurements were demonstrated with an effective time resolution of 100 msec, limited at this time by the scan rate of our mechanically tuned ECDL system. In Year 2 described in this progress report, the Toptica ECDL in the original system was replaced with a Sacher Lasers ECDL. The mode-hop-free tuning range and tuning rate of the Toptica ECDL were 25 GHz and a few Hz, respectively. The mode-hop-free tuning range and tuning rate of the Sacher Lasers ECDL were 90 GHz and a few hundred Hz, respectively. The Sacher Lasers ECDL thus allows us to scan over the entire NO absorption line and to determine the absorption baseline with increased accuracy and precision. The increased tuning rate is an advantage in ...
Date: September 30, 2004
Creator: Caton, Jerald A.; Annamalai, Kalyan & Lucht, Robert P.
Partner: UNT Libraries Government Documents Department

L.C.C. laser isotope separation project progress report

Description: Progress is described in the following areas: matrix isolation of uranium hexafluoride in carbon monoxide host and obtainment of stable narrow bands in the 623cm{sup -1} region of uranium hexafluoride; and reactions of nitrogen oxide with uranium hexafluoride.
Date: December 2, 1974
Creator: Catalano, E.
Partner: UNT Libraries Government Documents Department

Kinetics and mechanisms of NO{sub x}: Char reduction. Quarterly technical progress report, 31 January 1995--30 April 1995

Description: This project is concerned with the mechanism of reduction of both NO and N{sub 2}O by carbons. It was recognized some years ago that NO formed during fluidized bed coal combustion can be heterogeneously reduced in-situ by the carbonaceous solid intermediates of combustion. This has been recently supplemented by the knowledge that heterogeneous reaction with carbon can also play an important role in reducing emissions of N{sub 2}, but that the NO-carbon reactions might also contribute to formation of N{sub 2}. The precise role of carbon in N{sub 2} reduction and formation has yet to be established. Interest in the N{sub 2} and N{sub 2}O-char reactions has been significant in connection with both combustor modeling, as well as in design of post-combustion NO{sub x} control strategies. In our studies, a DuPont thermogravimetric analyzer (TGA) is used for the char reactivity studies. The temperature and mass are recorded as function of time, using a Macintosh computer and software for simultaneous apparatus control and data acquisition. Specific surface areas of char samples were determined by the N{sub 2} BET method at 77 K. A standard flow-type adsorption device (Quantasorb) was used for the measurements. Prior to surface area analysis, all samples were outgassed in a flow of nitrogen at 573 K for 3 hours. The carbonaceous solids used were resin char, graphite, coconut char and a Wyodak coal char. As was noted in the last report, carbons derived from different original materials show quite similar behaviors, in terms of the trends, but there are significant differences in actual reaction rates. It was shown that the spread of the reaction rate data from different studies, when expressed on a mass of carbon reactant- or surface area-basis, was almost the same.
Date: August 1, 1995
Creator: Suuberg, E.M.; Lilly, W.D. & Aarna, I.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of waste Tank 241-BY-111: Results from samples collected on November 15, 1994

Description: This report describes results of the analyses of tank-headspace samples taken from the Hanford waste Tank 241-BY-111 (referred to as Tank By-111). Pacific Northwest Laboratory (PNL) contracted with Westinghouse Hanford company (WHC) to provide sampling devices and to analyze inorganic and organic analytes collected from the tank headspace and ambient air near the tank. The target analytes for TO- 14 compounds were extended to include 14 analytes identified by the Toxicological Review Panel for Tank C-103 and reported by Mahlum et al. (1994). Program management included these analytes for future tank analyses as identified in the fiscal year work plan. This plan is attached to a letter dated 9/30/94 and addressed to Mr. T.J. Kelly of WHC. The plan also requires PNL to analyze for the permanent gases as shown in Table 3.7. The sample job was designated S4083, and samples wee collected by WHC on November 16, 1994, using the vapor sampling system (VSS). The results of the analyses are expected to be used to estimate the potential toxicity of tank-headspace gas as described in Data Quality Objectives for Generic In-Tank Health and Safety Vapor Issue Resolution, WHC-SD-WM-DQO-002, Rev. 0.
Date: June 1, 1995
Creator: Lucke, R.B.; Ligotke, M.W. & McVeety, B.D.
Partner: UNT Libraries Government Documents Department


Description: The focus of this program is to provide insight into the formation and minimization of NO{sub x} in multi-burner arrays, such as those that would be found in a typical utility boiler. Most detailed studies are performed in single-burner test facilities, and may not capture significant burner-to-burner interactions that could influence NO{sub x} emissions. Thus, investigations of such interactions were made by performing a combination of single and multiple burner experiments in a pilot-scale coal-fired test facility at the University of Utah, and by the use of computational combustion simulations to evaluate full-scale utility boilers. In addition, fundamental studies on nitrogen release from coal were performed to develop greater understanding of the physical processes that control NO formation in pulverized coal flames--particularly under low NO{sub x} conditions. A CO/H{sub 2}/O{sub 2}/N{sub 2} flame was operated under fuel-rich conditions in a flat flame reactor to provide a high temperature, oxygen-free post-flame environment to study secondary reactions of coal volatiles. Effects of temperature, residence time and coal rank on nitrogen evolution and soot formation were examined. Elemental compositions of the char, tar and soot were determined by elemental analysis, gas species distributions were determined using FTIR, and the chemical structure of the tar and soot was analyzed by solid-state {sup 13}C NMR spectroscopy. A laminar flow drop tube furnace was used to study char nitrogen conversion to NO. The experimental evidence and simulation results indicated that some of the nitrogen present in the char is converted to nitric oxide after direct attack of oxygen on the particle, while another portion of the nitrogen, present in more labile functionalities, is released as HCN and further reacts in the bulk gas. The reaction of HCN with NO in the bulk gas has a strong influence on the overall conversion of char-nitrogen to nitric oxide; ...
Date: January 1, 2002
Creator: Eddings, E.G.; Molina, A.; Pershing, D.W.; Sarofim, A.F.; Fletcher, T.H.; Zhang, H. et al.
Partner: UNT Libraries Government Documents Department


Description: This study was undertaken in order to improve understanding of several aspects of the NO-carbon reaction. This reaction is of practical importance in combustion systems, but its close examination also provides some fundamental insight into oxidizing gas-carbon reactions. As part of this study, a comprehensive literature review of earlier work on this reaction has been published (Aarna and Suuberg, Fuel, 1997, 76, 475-491). It has been thought for some time that the kinetics of the NO-carbon reaction are unusual, in that they often show a two-regime Arrhenius behavior. It has, however, turned out during this work that NO is not alone in this regard. In this laboratory, we also uncovered evidence of two kinetic regime behavior in CO{sub 2} gasification. In another laboratory, a former colleague has identified the same behavior in N{sub 2}O. The low temperature reaction regime always shows an activation energy which is lower than that in the high temperature regime, leaving little doubt that a shift in mechanism, as opposed to transport limitations, dictates the behavior. The activation energy of the low temperature regime of these reactions is typically less than 100 kJ/mol, and the activation energy of the high temperature regime is generally considerably in excess of this value. In this study, we have resolved some apparent inconsistencies in the explanation of the low temperature regime, whose rate has generally been ascribed to desorption-controlled processes. Part of the problem in characterization of the different temperature regimes is that they overlap to a high degree. It is difficult to probe the low temperature regime experimentally, because of slow relaxation of the surface oxides in that regime. Using careful experimental techniques, we were able to demonstrate that the low temperature regime is indeed characterized by zero order in NO, as it must be. A separate study is ...
Date: June 19, 1998
Creator: Suuberg, E.M.
Partner: UNT Libraries Government Documents Department