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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: García, 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

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

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

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

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: 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


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

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

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

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

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


Description: Magnetically tuned emission lines from ions and atoms were utilized to determine concentrations of NO gas with high selectivity and high sensitivity. One of the Zeeman components of an emission line was shifted to exactly coincide with a single rotational-vibrational lines of NO, whereas the other component was shifted away from the NO line. The coincident component indicated the extent of NO absorption and the noncoincident component measured the extent of background absorption. By making use of a differential measurement, light scattering and molecular absorption caused by coexisting small particles and gases were cancelled out. Detection limits of NO in N{sub 2} were about 30 ppb and 150 ppb at low pressure and at atmospheric pressure, respectively.
Date: March 1, 1979
Creator: Koizumi, Hideaki; Hadeishi, Tetsuo & McLaughlin, Ralph D.
Partner: UNT Libraries Government Documents Department

Aqueous and gaseous nitrogen losses induced by fertilizer application

Description: In recent years concern has grown over the contribution of nitrogen (N) fertilizer use to nitrate (NO{sub 3}{sup -}) water pollution and nitrous oxide (N{sub 2}O), nitric oxide (NO), and ammonia (NH{sub 3}) atmospheric pollution. Characterizing soil N effluxes is essential in developing a strategy to mitigate N leaching and emissions to the atmosphere. In this paper, a previously described and tested mechanistic N cycle model (TOUGHREACT-N) was successfully tested against additional observations of soil pH and N{sub 2}O emissions after fertilization and irrigation, and before plant emergence. We used TOUGHREACT-N to explain the significantly different N gas emissions and nitrate leaching rates resulting from the different N fertilizer types, application methods, and soil properties. The N{sub 2}O emissions from NH{sub 4}{sup +}-N fertilizer were higher than from urea and NO{sub 3}{sup -}-N fertilizers in coarse-textured soils. This difference increased with decreases in fertilization application rate and increases in soil buffering capacity. In contrast to methods used to estimate global terrestrial gas emissions, we found strongly non-linear N{sub 2}O emissions as a function of fertilizer application rate and soil calcite content. Speciation of predicted gas N flux into N{sub 2}O and N{sub 2} depended on pH, fertilizer form, and soil properties. Our results highlighted the need to derive emission and leaching factors that account for fertilizer type, application method, and soil properties.
Date: January 15, 2009
Creator: Gu, C.; Maggi, F.; Riley, W.J.; Hornberger, G.M.; Xu, T.; Oldenburg, C.M. et al.
Partner: UNT Libraries Government Documents Department

Direct catalytic decomposition of nitric oxide; Quarterly technical progress report No. 9, October--December 1993

Description: This project investigates a suitable catalyst system for the direct nitric oxide decomposition in post-combustion gas streams. This process does not use a reductant, such as the ammonia used in the Selective Catalytic Reduction (SCR) of NO{sub x} to nitrogen. Therefore, it is a greatly simplified process basically involving passing the flue gas through a catalytic converter. A systematic study of water vapor effects on the structure and Cu{sup 2+} ion exchange capacity of parent ZSM-5 zeolites and on the catalytic activity of the Cu-ZSM-5 and metal ion (mg{sup 2+} and Ce{sup 3+}) modified Cu-ZSM-5 catalysts for NO decomposition has been performed during this quarter. Mg{sup 2+} and Ce{sup 3+} cocations in copper ion-exchanged ZSM-5 zeolites display a positive effect on the decomposition of nitric oxide to nitrogen and oxygen. The catalytic activity of a Cu-ZSM-5 catalyst was examined after it was exposed to different inert and oxygen-containing gas streams. The results show that the steady-state catalyst activity is not sensitive to three treatments.
Date: December 31, 1993
Creator: Flytzani-Stephanopoulos, M.; Sarofim, A. F.; Zhang, Yanping & Sun, Tao
Partner: UNT Libraries Government Documents Department

Analysis of Halogen-Mercury Reactions in Flue Gas

Description: Oxidized mercury species may be formed in combustion systems through gas-phase reactions between elemental mercury and halogens, such as chorine or bromine. This study examines how bromine species affect mercury oxidation in the gas phase and examines the effects of mixtures of bromine and chlorine on extents of oxidation. Experiments were conducted in a bench-scale, laminar flow, methane-fired (300 W), quartz-lined reactor in which gas composition (HCl, HBr, NO{sub x}, SO{sub 2}) and temperature profile were varied. In the experiments, the post-combustion gases were quenched from flame temperatures to about 350 C, and then speciated mercury was measured using a wet conditioning system and continuous emissions monitor (CEM). Supporting kinetic calculations were performed and compared with measured levels of oxidation. A significant portion of this report is devoted to sample conditioning as part of the mercury analysis system. In combustion systems with significant amounts of Br{sub 2} in the flue gas, the impinger solutions used to speciate mercury may be biased and care must be taken in interpreting mercury oxidation results. The stannous chloride solution used in the CEM conditioning system to convert all mercury to total mercury did not provide complete conversion of oxidized mercury to elemental, when bromine was added to the combustion system, resulting in a low bias for the total mercury measurement. The use of a hydroxylamine hydrochloride and sodium hydroxide solution instead of stannous chloride showed a significant improvement in the measurement of total mercury. Bromine was shown to be much more effective in the post-flame, homogeneous oxidation of mercury than chlorine, on an equivalent molar basis. Addition of NO to the flame (up to 400 ppmv) had no impact on mercury oxidation by chlorine or bromine. Addition of SO{sub 2} had no effect on mercury oxidation by chlorine at SO{sub 2} concentrations below about ...
Date: January 1, 2010
Creator: Buitrago, Paula; Silcox, Geoffrey; Senior, Constance & Otten, Brydger Van
Partner: UNT Libraries Government Documents Department

Measurement of Helical Trajectories in Chemical Reactions by Ion Imaging

Description: During the first year of this grant we developed methods to measure the sense of rotation of the nitric oxide molecule (NO) using a circularly polarized laser probe and with ion imaging detection. The method was applied to the measurement of the correlation of rotational angular momentum orientation with recoil direction in the photodissociation of NO{sub 2}. [''Detection of ''ended'' NO recoil in the 355 nm NO2 photodissociation mechanism'', V.K. Nestorov and J.I. Cline, J. Chem. Phys. 111, 5287-5290 (1999)]. The photodissociation work was performed at the University of Nevada with additional, partial support from NSF. In the summer of 1999 this technique was transported to and implemented at the Combustion Research Facility at Sandia National Laboratory in Livermore, CA in a study of rotationally inelastic collisions of NO molecules with Ar atoms. The summer 1999 experiments at Sandia demonstrated that it is possible to detect collision-induced rotational alignment (preferred planes of rotation) for product molecules. During the late summer and fall of 1999 the P.I. and student James Barr developed a theoretical method for quantifying the angular momentum alignment and for extracting it from ion images. During the winter and spring of 2000 (January-May) the P.I. was in residence at Sandia National Laboratory in Livermore during a sabbatical leave from the University of Nevada. During this time the P.I. collaborated with Sandia P.I. Dr. David Chandler and Sandia postdoctorals Thomas Lorenz and Elisabeth Wade in experiments measuring both rotational alignment and rotational orientation (preferred senses of rotation) in collisions of NO with Ar. Graduate student James Barr continued these experiments at Sandia through the end of June 2000. The success of our experimental techniques for measuring collisional alignment and the theoretical methods we have developed for extracting quantitative alignment parameters from ion images. Spectroscopic probing of products by resonance-enhanced ...
Date: February 10, 2003
Creator: Cline, Joseph I.
Partner: UNT Libraries Government Documents Department

The role of prostaglandins, nitric oxide and oxygen in the ductus arteriosi of the pre-term chicken embryo (Gallus domesticus).

Description: The chicken ductus arteriosi (DA) are two embryonic blood vessels that shunt blood away from the non-ventilated lungs and towards the body and chorioallantoic membrane. I show that prostaglandins have a diminished role in maintaining chicken DA patency and nitric oxide inhibits oxygen induced contraction of the day 19 proximal DA in a time dependent manner. The pathways governing oxygen induced contraction in the chicken DA are similar to those found in mammals and include contributions from ROS, Kv channels, L-type Ca2+ channels, and the Rho kinase pathway. Longer exposure to high oxygen generates increased oxygen induced constriction of the day 19 DA that may be mediated through the Rho kinase pathway.
Date: December 2007
Creator: Greyner, Henry José
Partner: UNT Libraries