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Research paper thumbnail of Beyond the Ångström Exponent: Probing Additional Information in Spectral Curvature and Variability of In Situ Aerosol Hyperspectral (0.3–0.7 μm) Optical Properties

Journal of Geophysical Research: Atmospheres

Research paper thumbnail of Airborne observations of aircraft aerosol emissions I: Total nonvolatile particle emission indices

Geophysical Research Letters, 1998

Research paper thumbnail of Impact of aircraft emissions on NO x in the lowermost stratosphere at northern midlatitudes

Geophysical Research Letters, 1999

Airborne measurements of NOx, total reactive nitrogen (NOy), 03, and condensation nuclei (CN) wer... more Airborne measurements of NOx, total reactive nitrogen (NOy), 03, and condensation nuclei (CN) were made within air traffic corridors over the U.S. and North Atlantic regions (35-60 øN) in the fall of 1997. NOx and NOy data obtained in the lowermost stratosphere (LS) were examined using the calculated increase in NOy (ANOy) along five-day back trajectories as a parameter to identify possible effects of aircraft on reactive nitrogen. It is very likely that aircraft emissions had a significant impact on the NOx levels in the LS inasmuch as the NO• mixing ratios at 8.5-12 km were significantly correlated with the independent parameters of aircraft emissions, i.e., ANOy levels and CN values. In order to estimate quantitatively the impact of aircraft emissions on NOx and CN, the background levels of CN and NO• at 03 = 100-200 ppbv were derived from the correlations of these quantities with ANOy. On average, the aircraft emissions are estimated to have increased the NOx and CN values by 130 pptv and 400 STP cm '3, respectively, which corresponds to 70+30 % and 30+_20 % of the observed median values.

Research paper thumbnail of The effects of a proton source on the electrochemical reduction of the chlorinated nitrobenzenes in dimethylsulfoxide, dimethylformamide and acetonitrile

Cyclic voltammograms of the chlorinated nitrobenzenes and nitrobenzene itself were obtained in DM... more Cyclic voltammograms of the chlorinated nitrobenzenes and nitrobenzene itself were obtained in DMSO, DMF and AN with and without the addition of a proton source. Reduction potentials for all primary processes were obtained from the voltammograms. The first reduction wave corresponds to the one-electron reversible transfer to form the radical anion. The second reduction wave represents the addition of more electrons to form the dianion followed by loss of chlorine with subsequent reduction or protonation. The protonated species can either deprotonate or lose hydroxide to yield nitroso compounds. With proton addition, the competition between processes is altered and protonation increases. The potentials of the "irreversible" waves shift anodically and some waves are no longer seen as the corresponding process is no longer as competitive with increased protonation. Changes in reduction pathways are noted, sigma rho calculations for the radical anion are obtained and these fac...

Research paper thumbnail of The effects of a proton source on the electrochemical reduction of the chlorinated nitrobenzenes in dimethylsulfoxide, dimethylformamide and acetonitrile

Research paper thumbnail of Evaluation of sodium nitrite as a corrosion inhibitor for USS Monitor artifacts

Studies in Conservation, 2014

The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects p... more The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO 2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO 2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO 2 , replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO 2 does not easily oxidize to NO 3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.

Research paper thumbnail of Evaluation of sodium nitrite as a corrosion inhibitor for USS Monitor artifacts

Studies in Conservation , 2015

The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects p... more The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO 2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO 2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO 2 , replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO 2 does not easily oxidize to NO 3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.

Research paper thumbnail of Beyond the Ångström Exponent: Probing Additional Information in Spectral Curvature and Variability of In Situ Aerosol Hyperspectral (0.3–0.7 μm) Optical Properties

Journal of Geophysical Research: Atmospheres

Research paper thumbnail of Airborne observations of aircraft aerosol emissions I: Total nonvolatile particle emission indices

Geophysical Research Letters, 1998

Research paper thumbnail of Impact of aircraft emissions on NO x in the lowermost stratosphere at northern midlatitudes

Geophysical Research Letters, 1999

Airborne measurements of NOx, total reactive nitrogen (NOy), 03, and condensation nuclei (CN) wer... more Airborne measurements of NOx, total reactive nitrogen (NOy), 03, and condensation nuclei (CN) were made within air traffic corridors over the U.S. and North Atlantic regions (35-60 øN) in the fall of 1997. NOx and NOy data obtained in the lowermost stratosphere (LS) were examined using the calculated increase in NOy (ANOy) along five-day back trajectories as a parameter to identify possible effects of aircraft on reactive nitrogen. It is very likely that aircraft emissions had a significant impact on the NOx levels in the LS inasmuch as the NO• mixing ratios at 8.5-12 km were significantly correlated with the independent parameters of aircraft emissions, i.e., ANOy levels and CN values. In order to estimate quantitatively the impact of aircraft emissions on NOx and CN, the background levels of CN and NO• at 03 = 100-200 ppbv were derived from the correlations of these quantities with ANOy. On average, the aircraft emissions are estimated to have increased the NOx and CN values by 130 pptv and 400 STP cm '3, respectively, which corresponds to 70+30 % and 30+_20 % of the observed median values.

Research paper thumbnail of The effects of a proton source on the electrochemical reduction of the chlorinated nitrobenzenes in dimethylsulfoxide, dimethylformamide and acetonitrile

Cyclic voltammograms of the chlorinated nitrobenzenes and nitrobenzene itself were obtained in DM... more Cyclic voltammograms of the chlorinated nitrobenzenes and nitrobenzene itself were obtained in DMSO, DMF and AN with and without the addition of a proton source. Reduction potentials for all primary processes were obtained from the voltammograms. The first reduction wave corresponds to the one-electron reversible transfer to form the radical anion. The second reduction wave represents the addition of more electrons to form the dianion followed by loss of chlorine with subsequent reduction or protonation. The protonated species can either deprotonate or lose hydroxide to yield nitroso compounds. With proton addition, the competition between processes is altered and protonation increases. The potentials of the "irreversible" waves shift anodically and some waves are no longer seen as the corresponding process is no longer as competitive with increased protonation. Changes in reduction pathways are noted, sigma rho calculations for the radical anion are obtained and these fac...

Research paper thumbnail of The effects of a proton source on the electrochemical reduction of the chlorinated nitrobenzenes in dimethylsulfoxide, dimethylformamide and acetonitrile

Research paper thumbnail of Evaluation of sodium nitrite as a corrosion inhibitor for USS Monitor artifacts

Studies in Conservation, 2014

The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects p... more The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO 2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO 2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO 2 , replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO 2 does not easily oxidize to NO 3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.

Research paper thumbnail of Evaluation of sodium nitrite as a corrosion inhibitor for USS Monitor artifacts

Studies in Conservation , 2015

The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects p... more The use of sodium nitrite (NaNO 2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO 2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO 2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO 2 , replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO 2 does not easily oxidize to NO 3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.