Sample records for nox trap catalysts
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Effect of reductive treatments on Pt behavior and NOx storage in lean NOx trap catalysts
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Xianqin; Kim, Do Heui; Kwak, Ja Hun
2011-10-01
Lean NOx trap (LNT) catalysts represent a promising approach to meet increasingly stringent NOx emission regulations on diesel and other lean-burn engines. Pt material properties, including dispersion and particle size, are known to be important factors in determining NOx uptake performance, since Pt provides active sites for NO oxidation to NO2 necessary for storing NOx as nitrates, and for the reduction of nitrates to N2. In this work, the physicochemical properties of Pt in Pt-BaO/Al2O3 LNT catalysts, such as the Pt accessible surface area and particle size, were investigated by using various tools, such as irreversible volumetric H2 chemisorption, highmore » resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), following successive reductive treatments at elevated temperatures. NOx uptake activities were also measured to establish a relationship between the properties of Pt and NOx storage following identical high-temperature reductive treatments. We find that the reductive treatments of Pt-BaO/Al2O3 lean NOx trap catalysts at temperatures up to 500 ºC promote a significant increase in NOx uptake explained, in part, by an induced close interaction between Pt and BaO phases in the catalyst, thus enabling facilitation of the NOx storage process.« less
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Fremerey, Peter; Reiß, Sebastian; Geupel, Andrea; Fischerauer, Gerhard; Moos, Ralf
2011-01-01
Recently, it has been shown that the degree of loading of several types of automotive exhaust aftertreatment devices can be directly monitored in situ and in a contactless way by a microwave-based method. The goal of this study was to clarify whether this method can also be applied to NOx storage and reduction catalysts (lean NOx traps) in order to obtain further knowledge about the reactions occurring in the catalyst and to compare the results with those obtained by wirebound NOx loading sensors. It is shown that both methods are able to detect the different catalyst loading states. However, the sensitivity of the microwave-based method turned out to be small compared to that previously observed for other exhaust aftertreatment devices. This may limit the practical applicability of the microwave-based NOx loading detection in lean NOx traps. PMID:22164074
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Characteristics of Pt-K/MgAl2O4 lean NOx trap catalysts
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, Do Heui; Mudiyanselage, Kumudu K.; Szanyi, Janos
2012-04-30
We report the various characteristics of Pt-K/MgAl{sub 2}O{sub 4} lean NOx trap (LNT) catalysts including the effect of K loading on nitrate formation/decomposition, NOx storage activity and durability. Upon the adsorption of NO{sub 2} on K/MgAl{sub 2}O{sub 4} samples, potassium nitrates formed on Mg-related sites in MgAl{sub 2}O{sub 4} support are observed, in addition to the typical two potassium nitrates (ionic and bidentate) formed also on Al{sub 2}O{sub 3} supported sample. Based on NO{sub 2} TPD and FTIR results, the Mg-bound KNO{sub 3} thermally decompose at higher temperature than Al-bound KNO{sub 3}, implying its superior thermal stability. At a potassiummore » loading of 5wt%, the temperature of maximum NOx uptake (T{sub max}) is 300 C. Increasing the potassium loading from 5wt% to 10 wt%, the T{sub max} gradually shifted from 300 C to 450 C, indicating the dependence of T{sub max} on the potassium loading. However, increase in potassium loading above 10 wt% only gives rise to the reduction in the overall NOx storage capacity. This work also underlines the obstacles these materials have prior to their practical application (e.g., durability and sulfur poisoning/ removal). This work provides fundamental understanding of Pt-K/MgAl{sub 2}O{sub 4}-based lean NOx trap catalysts, which could be good candidates for high temperature LNT applications.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Parks, II, James E; Ponnusamy, Senthil
2006-01-01
Lean NOx trap catalysis has demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as "regeneration" since the catalyst is reactivated for more NOx trapping after NOx purge. Creating the rich exhaust conditions for regeneration can be accomplished by catalytic partial oxidation of methane in the exhaust system. Furthermore, catalytic reforming of partial oxidation exhaust can enablemore » increased quantities of H2 which is an excellent reductant for lean NOx trap regeneration. It is critical to maintain clean and efficient partial oxidation and reforming processes to keep the lean NOx trap functioning properly and to reduce extra fuel consumption from the regeneration process. Although most exhaust constituents do not impede partial oxidation and reforming, some exhaust constituents may negatively affect the catalysts and result in loss of catalytic efficiency. Of particular concern are common catalyst poisons sulfur, zinc, and phosphorous. These poisons form in the exhaust through combustion of fuel and oil, and although they are present at low concentrations, they can accumulate to significant levels over the life of an engine system. In the work presented here, the effects of sulfur on the partial oxidation and reforming catalytic processes were studied to determine any durability limitations on the production of reductants for lean NOx trap catalyst regeneration.« less
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Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications
DOE Office of Scientific and Technical Information (OSTI.GOV)
Parks, II, James E; Storey, John Morse; Theiss, Timothy J
the efficiency and emissions of natural gas reciprocating engines are being pursued. Approaches include: stoichiometric engine operation with exhaust gas recirculation and three-way catalysis, advanced combustion modes such as homogeneous charge compression ignition, and extension of the lean combustion limit with advanced ignition concepts and/or hydrogen mixing. The research presented here addresses the technical approach of combining efficient lean spark-ignited natural gas combustion with low emissions obtained from a lean NOx trap catalyst aftertreatment system. This approach can be applied to current lean engine technology or advanced lean engines that may result from related efforts in lean limit extension. Furthermore, the lean NOx trap technology has synergy with hydrogen-assisted lean limit extension since hydrogen is produced from natural gas during the lean NOx trap catalyst system process. The approach is also applicable to other lean engines such as diesel engines, natural gas turbines, and lean gasoline engines; other research activities have focused on those applications. Some commercialization of the technology has occurred for automotive applications (both diesel and lean gasoline engine vehicles) and natural gas turbines for stationary power. The research here specifically addresses barriers to commercialization of the technology for large lean natural gas reciprocating engines for stationary power. The report presented here is a comprehensive collection of research conducted by Oak Ridge National Laboratory (ORNL) on lean NOx trap catalysis for lean natural gas reciprocating engines. The research was performed in the Department of Energy's ARES program from 2003 to 2007 and covers several aspects of the technology. All studies were conducted at ORNL on a Cummins C8.3G+ natural gas engine chosen based on industry input to simulate large lean natural gas engines. Specific technical areas addressed by the research include: NOx reduction efficiency
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Luo, Jinyong; Gao, Feng; Karim, Ayman M.
MgAlOx mixed oxides were employed as supports for potassium-based lean NOx traps (LNTs) targeted for high temperature applications. Effects of support compositions, K/Pt loadings, thermal aging and catalyst regeneration on NOx storage capacity were systematically investigated. The catalysts were characterized by XRD, NOx-TPD, TEM, STEM-HAADF and in-situ XAFS. The results indicate that MgAlOx mixed oxides have significant advantages over conventional gamma-Al2O3-supports for LNT catalysts, in terms of high temperature NOx trapping capacity and thermal stability. First, as a basic support, MgAlOx stabilizes stored nitrates (in the form of KNO3) to much higher temperatures than mildly acidic gamma-Al2O3. Second, MgAlOx minimizesmore » Pt sintering during thermal aging, which is not possible for gamma-Al2O3 supports. Notably, combined XRD, in-situ XAFS and STEM-HAADF results indicate that Pt species in the thermally aged Pt/MgAlOx samples are finely dispersed in the oxide matrix as isolated atoms. This strong metal-support interaction stabilizes Pt and minimizes the extent of sintering. However, such strong interactions result in Pt oxidation via coordination with the support so that NO oxidation activity can be adversely affected after aging which, in turn, decreases NOx trapping ability for these catalysts. Interestingly, a high-temperature reduction treatment regenerates essentially full NOx trapping performance. In fact, regenerated Pt/K/MgAlOx catalyst exhibits much better NOx trapping performance than fresh Pt/K/Al2O3 LNTs over the entire temperature range investigated here. In addition to thermal aging, Pt/K loading effects were systemically studied over the fresh samples. The results indicate that NOx trapping is kinetically limited at low temperatures, while thermodynamically limited at high temperatures. A simple conceptual model was developed to explain the Pt and K loading effects on NOx storage. An optimized K loading, which allows balancing between the
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Luo, Jinyong; Gao, Feng; Kim, Do Heui
2014-03-31
The effects of K loading and thermal aging on the structural properties and high temperature performance of Pt/K/Al2O3 lean NOx trap (LNT) catalysts were investigated using in situ X-ray diffraction (XRD), temperature-programmed decomposition/desorption of NOx (NOx-TPD), transmission electron microscopy (TEM), NO oxidation and NOx storage tests. In situ XRD results demonstrate that KNO3 becomes extremely mobile on the Al2O3 surface, and experiences complex transformations between orthorhombic and rhombohedral structures, accompanied by sintering, melting and thermal decomposition upon heating. NOx storage results show an optimum K loading around 10% for the best performance at high temperatures. At lower K loadings wheremore » the majority of KNO3 stays as a surface layer, the strong interaction between KNO3 and Al2O3 promotes KNO3 decomposition and deteriorates high-temperature performance. At K loadings higher than 10%, the performance drop is not caused by NOx diffusion limitations as for the case of barium-based LNTs, but rather from the blocking of Pt sites by K species, which adversely affects NO oxidation. Thermal aging at 800 ºC severely deactivates the Pt/K/Al2O3 catalysts due to Pt sintering. However, in the presence of potassium, some Pt remains in a dispersed and oxidized form. These Pt species interact strongly with K and, therefore, do not sinter. After a reduction treatment, these Pt species remain finely dispersed, contributing to a partial recovery of NOx storage performance.« less
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Alkali- and Sulfur-Resistant Tungsten-Based Catalysts for NOx Emissions Control.
Huang, Zhiwei; Li, Hao; Gao, Jiayi; Gu, Xiao; Zheng, Li; Hu, Pingping; Xin, Ying; Chen, Junxiao; Chen, Yaxin; Zhang, Zhaoliang; Chen, Jianmin; Tang, Xingfu
2015-12-15
The development of catalysts with simultaneous resistance to alkalis and sulfur poisoning is of great importance for efficiently controlling NOx emissions using the selective catalytic reduction of NOx with NH3 (SCR), because the conventional V2O5/WO3-TiO2 catalysts often suffer severe deactivation by alkalis. Here, we support V2O5 on a hexagonal WO3 (HWO) to develop a V2O5/HWO catalyst, which has exceptional resistance to alkali and sulfur poisoning in the SCR reactions. A 350 μmol g(-1) K(+) loading and the presence of 1,300 mg m(-3) SO2 do not almost influence the SCR activity of the V2O5/HWO catalyst, and under the same conditions, the conventional V2O5/WO3-TiO2 catalysts completely lost the SCR activity within 4 h. The strong resistance to alkali and sulfur poisoning of the V2O5/HWO catalysts mainly originates from the hexagonal structure of the HWO. The HWO allows the V2O5 to be highly dispersed on the external surfaces for catalyzing the SCR reactions and has the relatively smooth surfaces and the size-suitable tunnels specifically for alkalis' diffusion and trapping. This work provides a useful strategy to develop SCR catalysts with exceptional resistance to alkali and sulfur poisoning for controlling NOx emissions from the stationary source and the mobile source.
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NASA Astrophysics Data System (ADS)
Ha, T. M. P.; Luong, N. T.; Le, P. N.
2016-11-01
In Vietnam for recent years, a large amount of hazardous waste containing nickel (Ni) derived from discharged catalyst of fertilizer plants has caused environmental problems in landfill overloading and the risk of soil or surface water sources pollution. Taking advantage of discharged catalyst, recycling Ni components and then synthesizing new catalysts apply for mono-nitrogen oxides (NOx) treatments is an approach to bring about both economic and environmental benefits. This study was carried out with the main objective: Evaluate the performance of modified catalysts (using recovered Ni from the discharged RKS-2-7H catalyst of Phu My Fertilizer Plant) on NOx treatment. The catalysts was synthesized and modified with active phases consist of recovered Ni and commercial Barium oxide (BaO), Manganese dioxide (MnO2) / Cerium (IV) oxide (CeO2) on the support Aluminium oxide (γ-Al2O3). The results show that the modified catalysts with Ni, Ba, Ce was not more beneficial for NOx removal than which with Ni, Ba, Mn. 98% NOx removal at 350°C with the start temperature at 115°C and the T60 value at 307°C can be obtained with 10Ni10Ba10Mn/Al catalyst.
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Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process.
Guo, Yufang; Liao, Xiaobin; Fu, Mingli; Huang, Haibao; Ye, Daiqi
2015-02-01
Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression. Copyright © 2014. Published by Elsevier B.V.
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Discovery of Novel NOx Catalysts for CIDI Applications by High-throughput Methods
DOE Office of Scientific and Technical Information (OSTI.GOV)
Blint, Richard J.
DOE project DE-PS26-00NT40758 has developed very active, lean exhaust, NOx reduction catalysts that have been tested on the discovery system, laboratory reactors and engine dynamometer systems. The goal of this project is the development of effective, affordable NOx reduction catalysts for lean combustion engines in the US light duty vehicle market which can meet Tier II emission standards with hydrocarbons based reductants for reducing NOx. General Motors (prime contractor) along with subcontractors BASF (Engelhard) (a catalytic converter developer) and ACCELRYS (an informatics supplier) carried out this project which began in August of 2002. BASF (Engelhard) has run over 16,000 testsmore » of 6100 possible catalytic materials on a high throughput discovery system suitable for automotive catalytic materials. Accelrys developed a new database informatics system which allowed material tracking and data mining. A program catalyst was identified and evaluated at all levels of the program. Dynamometer evaluations of the program catalyst both with and without additives show 92% NOx conversions on the HWFET, 76% on the US06, 60% on the cold FTP and 65% on the Set 13 heavy duty test using diesel fuel. Conversions of over 92% on the heavy duty FTP using ethanol as a second fluid reductant have been measured. These can be competitive with both of the alternative lean NOx reduction technologies presently in the market. Conversions of about 80% were measured on the EUDC for lean gasoline applications without using active dosing to adjust the C:N ratio for optimum NOx reduction at all points in the certification cycle. A feasibility analysis has been completed and demonstrates the advantages and disadvantages of the technology using these materials compared with other potential technologies. The teaming agreements among the partners contain no obstacles to commercialization of new technologies to any potential catalyst customers.« less
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Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.
Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu
2015-06-02
A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.
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Mei, Xueyi; Yan, Qinghua; Lu, Peng; Wang, Junya; Cui, Yuhan; Nie, Yu; Umar, Ahmad; Wang, Qiang
2017-01-01
Pt/K2CO3/MgAlOx–reduced graphene oxide (Pt/K/MgAlOx–rGO) hybrids were synthesized, characterized and tested as a promising NOx storage and reduction (NSR) catalyst. Mg–Al layered double hydroxides (LDHs) were grown on rGO via in situ hydrothermal crystallization. The structure and morphology of samples were thoroughly characterized using various techniques. Isothermal NOx adsorption tests indicated that MgAlOx–rGO hybrid exhibited better NOx trapping performance than MgAlOx, from 0.44 to 0.61 mmol · g−1, which can be attributed to the enhanced particle dispersion and stabilization. In addition, a series of MgAlOx–rGO loaded with 2 wt% Pt and different loadings (5, 10, 15, and 20 wt%) of K2CO3 (denoted as Pt/K/MgAlOx–rGO) were obtained by sequential impregnation. The influence of 5% H2O on the NOx storage capacity of MgAlOx–rGO loaded with 2 wt% Pt and 10% K2CO3 (2Pt/10 K/MgAlOx–rGO) catalyst was also evaluated. In all, the 2Pt/10 K/MgAlOx–rGO catalyst not only exhibited high thermal stability and NOx storage capacity of 1.12 mmol · g−1, but also possessed excellent H2O resistance and lean–rich cycling performance, with an overall 78.4% of NOx removal. This work provided a new scheme for the preparation of highly dispersed MgAlOx–rGO hybrid based NSR catalysts. PMID:28205630
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Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment
Moos, Ralf
2010-01-01
Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters. PMID:22163575
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Experimental research of technology activating catalysts for SCR DeNOx in boiler
NASA Astrophysics Data System (ADS)
Zeng, Xi; Yang, Zhengde; Li, Yan; Chen, Donglin
2018-01-01
In order to improve activity of the catalysts used in SCR DeNOx system of flue gas, a series of catalysts activated by different activating liquids under varied conditions in boiler directly were conducted. Then these catalysts were characterized by SEM, FT-IR and BET technology. And NO conversions of the activated catalysts were studied and compared with that of inactivated catalyst. The above experiment shows that NO conversion of the activated catalyst can be up to 99%, which 30% higher than that of inactivated catalyst, so activity of catalysts were improved greatly. Furthermore, optimal activating liquid labeled L2 and effective technology parameters were gained in the experiment.
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Hydrophobic Catalysts For Removal Of NOx From Flue Gases
NASA Technical Reports Server (NTRS)
Sharma, Pramod K.; Hickey, Gregory S.; Voecks, Gerald E.
1995-01-01
Improved catalysts for removal of nitrogen oxides (NO and NO2) from combustion flue gases formulated as composites of vanadium pentoxide in carbon molecular sieves. Promotes highly efficient selective catalytic reduction of NOx at relatively low temperatures while not being adversely affected by presence of water vapor and sulfur oxide gases in flue gas. Apparatus utilizing catalyst of this type easily integrated into exhaust stream of power plant to remove nitrogen oxides, generated in combustion of fossil fuels and contribute to formation of acid rain and photochemical smog.
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Catalysts as sensors--a promising novel approach in automotive exhaust gas aftertreatment.
Moos, Ralf
2010-01-01
Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NO(x) traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NO(x)-loading of lean NO(x) traps, and the soot loading of Diesel particulate filters.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, Do Heui; Mudiyanselage, Kumudu K.; Szanyi, Janos
2013-10-25
We have investigated nitrate formation and decomposition processes, and measured NOx storage performance on Pt-K2O/Al2O3 catalysts as a function of potassium loading. After NO2 adsorption at room temperature, ionic and bidentate nitrates were observed by fourier transform infra-red (FTIR) spectroscopy. The ratio of the former to the latter species increased with increasing potassium loading up to 10 wt%, and then stayed almost constant with additional K, demonstrating a clear dependence of loading on the morphology of the K species. Although both K2O(10)/Al2O3 and K2O(20)/Al2O3 samples have similar nitrate species after NO2 adsorption, the latter has more thermally stable nitrate speciesmore » as evidenced by FTIR and NO2 temperature programmed desorption (TPD) results. With regard to NOx storage performance, the temperature of maximum NOx uptake (Tmax) is 573 K up to a potassium loading of 10 wt%. As the potassium loading increases from 10 wt% to 20 wt%, Tmax shifted from 573 K to 723 K. Moreover, the amount of NO uptake (38 cm3 NOx/g catal) at Tmax increased more than three times, indicating that efficiency of K in storing NOx is enhanced significantly at higher temperature, in good agreement with the NO2 TPD and FTIR results. Thus, a combination of characterization and NOx storage performance results demonstrates an unexpected effect of potassium loading on nitrate formation and decomposition processes; results important for developing Pt-K2O/Al2O3 for potential applications as high temperature NOx storage-reduction catalysts.« less
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Park, Paul W.
2004-03-16
A lean NOx catalyst and method of preparing the same is disclosed. The lean NOx catalyst includes a ceramic substrate, an oxide support material, preferably .gamma.-alumina, deposited on the substrate and a metal promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium, cerium, vanadium, oxides thereof, and combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between about 80 to 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.
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NASA Astrophysics Data System (ADS)
Cai, Sixiang; Zhang, Dengsong; Shi, Liyi; Xu, Jing; Zhang, Lei; Huang, Lei; Li, Hongrui; Zhang, Jianping
2014-06-01
In this work, we successfully in situ decorated nickel foam with porous Ni-Mn oxide nanosheets (3DH-NM/NF) as 3D hierarchical monolith de-NOx catalysts via a simple hydrothermal reaction and calcination process. The catalysts were carefully examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and NH3 temperature-programmed desorption measurements. The results indicated that the nanosheets are composed of a Ni6Mn1O8 spinel and the metal species are uniformly dispersed in bi-metal oxides. As a result, the strong synergistic effects between the Mn and Ni species have been observed. The active oxygen species, reducible species and acidity are enhanced by the in situ formation of the nanosheets on the surface of nickel foam. These desirable features of 3DH-NM/NF catalysts bring about the excellent de-NOx performance. Moreover, the 3DH-NM/NF catalysts also present good stability and H2O resistance. Based on these favorable properties, 3DH-NM/NF could be considered as a promising candidate for the monolith de-NOx catalysts.In this work, we successfully in situ decorated nickel foam with porous Ni-Mn oxide nanosheets (3DH-NM/NF) as 3D hierarchical monolith de-NOx catalysts via a simple hydrothermal reaction and calcination process. The catalysts were carefully examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and NH3 temperature-programmed desorption measurements. The results indicated that the nanosheets are composed of a Ni6Mn1O8 spinel and the metal species are uniformly dispersed in bi-metal oxides. As a result, the strong synergistic effects between the Mn and Ni species have been observed. The active oxygen species, reducible species and acidity are enhanced by the in situ formation of the nanosheets on the
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Regeneration and sulfur poisoning behavior of In/H-BEA catalyst for NOx reduction by CH4
NASA Astrophysics Data System (ADS)
Pan, Hua; Jian, Yanfei; Yu, Yanke; He, Chi; Shen, Zhenxing; Liu, Hongxia
2017-04-01
Sulfur poisoning and regeneration behavior of In/H-BEA catalyst were carried out in NOx reduction by CH4. In/H-BEA catalyst exhibited a poor resistance to sulfur dioxide after addition of 200 ppm SO2 and 10 vol.% H2O into NO reduction with CH4 at 450 °C for 45 h. Sulfur poisoning of In/H-BEA was attributed to the inhibition of NOx adsorption on Brønsted acid sites, suppression of reaction intermediates generation on the active sites, and the formation of surface sulfate species. The formation of surface sulfate reduced the availability of surface active sites, blocked the pore structure and decreased the surface area of catalyst. These changes in chemical and textural properties resulted in a severe loss in the activity of sulfated In/H-BEA catalyst for NO reduction with CH4. H2 reduction is a promising technology for regeneration of In/H-BEA deactivated by SO2 for removing NOx from lean-burn and diesel exhausts. Indium sulfate could be reduced by H2 to InO+ with In2O3 and In(OH)2+ as the intermediates. The optimal parameters of H2 reduction was regeneration temperature of 400 °C and regeneration time of 60 min which completely recovered the catalytic activity of In/H-BEA.
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Stachurska, Patrycja; Kuterasiński, Łukasz; Dziedzicka, Anna; Górecka, Sylwia; Chmielarz, Lucjan; Łojewska, Joanna; Sitarz, Maciej
2018-01-01
Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C. PMID:29301370
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Thermally stable single-atom platinum-on-ceria catalysts via atom trapping
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jones, John; Xiong, Haifeng; DelaRiva, Andrew
2016-07-08
Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/ aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoringmore » the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst.« less
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[Selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalysts].
Sun, Hong; Quan, Xie; Zhang, Yao-bin; Zhao, Ya-zhi
2008-06-01
Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst was prepared by sol-gel and impregnation. Furthermore, selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst with propylene under lean burn condition was studied. The effects of the concentration of tetra-n-butyl titanate and dipcoat cycles on TiO2 washcoat were studied by SEM, and the effects of Pd concentration, O2 concentration and gas velocity on catalytic activity were investigated. The experimental results showed that the TiO2 washcoat on wire-mesh support is even and crack-free when the support is impregnated in 20.0% tetra- n-butyl titanate sol for 2 cycles. The NOx conversion decreases with Pd concentration increase. When Pd concentration is 0.23%, NOx conversion is highest. NOx conversion increases with oxygen concentration increase in the range of 1.5%-6.0%. However, when oxygen concentration is higher than 6.0%, NOx conversion decreases with increasing oxygen concentration. The NOx conversion decreases with gas velocity increase and its effect is severer at high temperature than low temperature.
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Control of diesel soot and NOx emissions with a particulate trap and EGR.
Liu, Rui-xiang; Gao, Xi-yan; Yang, De-sheng; Xu, Xiao-guang
2005-01-01
The exhaust gas recirculation (EGR), coupled with a high-collection efficiency particulate trap to simultaneously control smoke and NOx emissions from diesel engines were studied. This ceramic trap developed previously provided the soot cleaning efficiency of 99%, the regeneration efficiency reaches 80% and the ratio of success reaches 97%, which make EGR used in diesel possible. At the presence of EGR, opening of the regeneration control valve of the trap was over again optimized to compensate for the decrease of the oxygen concentration in the exhaust gas resulted from EGR. The results indicated the cleaning efficiency and regeneration performance of the trap were maintained at the same level except that the back pressure increased faster. A new EGR system was developed, which is based on a wide range oxygen (UEGO) sensor. Experiments were carried out under steady state conditions while maintaining the engine speed at 1600 r/min, setting the engine loads at 0%, 25%, 50%, 75% and 100% respectively. Throughout each test the EGR rate was kept at nine different settings and data were taken with the gas analyzer and UEGO sensor. Then, the EGR rate and engine load maps, which showed the tendencies of NOx, CO and HC emissions from diesel engine, were made using the measured data. Using the maps, the author set up the EGR regulation, the relationship between the optimal amounts of EGR flow and the equivalence ratio, sigma, where sigma = 14.5/AFR.
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Ce-Sn binary oxide catalyst for the selective catalytic reduction of NOx by NH3
NASA Astrophysics Data System (ADS)
Liu, Zhiming; Feng, Xu; Zhou, Zizheng; Feng, Yongjun; Li, Junhua
2018-01-01
Ce-Sn binary oxide catalysts prepared by the hydrothermal method have been investigated for the selective catalytic reduction (SCR) of NOx with NH3. Compared with pure CeO2 and SnO2, Ce-Sn binary oxide catalyst showed significantly higher NH3-SCR activity. Moreover, Ce-Sn catalyst showed high resistance against H2O and SO2. The high catalytic performance of Ce-Sn binary oxide is attributed to the synergetic effect between Ce and Sn species, which not only enhances the redox property of the catalyst but also increases the Lewis acidity, thus promoting the adsorption and activation of NH3 species, which contributes to improving the NH3-SCR performance.
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Liu, Zhihua; Ge, Yunshan; Tan, Jianwei; He, Chao; Shah, Asad Naeem; Ding, Yan; Yu, Linxiao; Zhao, Wei
2012-01-01
Two continuously regenerating diesel particulate filter (CRDPF) with different configurations and one particles oxidation catalyst (POC) were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO2, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO2/NOx significantly. The results of smoke emissions and particle number (PN) emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter (PM) and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO2/NOx. The PN emission results from two CRDPFs indicated that more NO2 generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO2 exposure in atmosphere.
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Jung, Hyounduk; Park, Eunseuk; Kim, Minsu; Jurng, Jongsoo
2017-03-01
The removal of NOx by catalytic technology at low temperatures is significant for treatment of flue gas in waste incineration plants, especially at temperatures below 200°C. A novel highly active TiO 2 -supported vanadium oxide catalyst at low temperatures (200-250°C) has been developed for the selective catalytic reduction (SCR) de-NOx process with ammonia. The catalyst was evaluated in a pilot-scale equipment, and the results were compared with those obtained in our previous work using laboratory scale (small volume test) equipment as well as bench-scale laboratory equipment. In the present work, we have performed our experiments in pilot scale equipment using a part of effluent flue gas that was obtained from flue gas cleaning equipment in a full-scale waste incineration plant in South Korea. Based on our previous work, we have prepared a TiO 2 -supported V 2 O 5 catalyst coated (with a loading of 7wt% of impregnated V 2 O 5 ) on a honeycomb cordierite monolith to remove NOx from a waste incinerator flue gas at low temperatures. The NOx (nitrogen oxides) removal efficiency of the SCR catalyst bed was measured in a catalyst fixed-bed reactor (flow rate: 100m 3 h -1 ) using real exhaust gas from the waste incinerator. The experimental results showed that the V 2 O 5 /TiO 2 SCR catalyst exhibited good DeNOx performance (over 98% conversion at an operating temperature of 300°C, 95% at 250°C, and 70% at 200°C), and was much better than the performance of commercial SCR catalysts (as low as 55% conversion at 250°C) under the same operating conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Rational design of template-free MnOx-CeO2 hollow nanotube as de-NOx catalyst at low temperature
NASA Astrophysics Data System (ADS)
Li, Chenlu; Tang, Xiaolong; Yi, Honghong; Wang, Lifeng; Cui, Xiaoxu; Chu, Chao; Li, Jingying; Zhang, Runcao; Yu, Qingjun
2018-01-01
MnOx-CeO2 hollow nanotube was synthesized for the low temperature selective catalytic reduction (SCR) of NOx with NH3. The nanotube was fabricated firstly through the interfacial oxidation-reduction reaction by dealing the Ce(OH)CO3 intermediate with KMnO4 aqueous solution, then followed by selective wash with HNO3. The catalysts were systematically examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption measurements and catalytic activity test. It was found that the as-prepared MnOx-CeO2-B nanotube exhibited best NOx removal efficiency among the catalysts investigated, where 96% NOx conversion at 100 °C at a space velocity of 30000 h-1 was obtained. Meanwhile, superior resistance to H2O and SO2 was achieved as well as high thermal stability. On the basis of various analysis results, the remarkable de-NOx performance of the MnOx-CeO2-B nanobube could be attributed to the uniform distribution of active species, abundant content of Mn4+ and Oα species, and especially the hollow porous architectures provided huge specific surface area and sufficient acidic sites.
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Diesel particulate abatement via wall-flow traps based on perovskite catalysts.
Fino, Debora; Russo, Nunzio; Saracco, Guido; Specchia, Vito
2003-01-01
It is probably redundant to stress how extensive are nowadays the attempts to reduce the diesel particulate emissions from automotive and stationary sources. The present paper looks into a technology relied on a catalytic trap based on a SiC wall-flow monolith lined with suitable catalysts for the sake of promoting a more complete and faster regeneration after particulate capture. All the major steps of the catalytic filter preparation are dealt with, including: the synthesis and choice of the proper catalyst and trap materials, the development of an in situ catalyst deposition technique, the bench testing of the derived catalytic wall-flow. The best catalyst selected was the perovskite La0.9K0.1Cr0.9O3-delta. The filtration efficiency and the pressure drop of the catalytic and non-catalytic monoliths were evaluated on a diesel engine bench under various operating conditions.
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Groβ, Andrea; Kremling, Michael; Marr, Isabella; Kubinski, David J.; Visser, Jacobus H.; Tuller, Harry L.; Moos, Ralf
2013-01-01
An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release. PMID:23549366
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Prikhodko, Vitaly Y.; Pihl, Josh A.; Toops, Todd J.
A prototype three-way catalyst (TWC) with NOX storage component was evaluated for ammonia (NH3) generation on a 2.0-liter BMW lean burn gasoline direct injection engine as a component in a passive ammonia selective catalytic reduction (SCR) system. The passive NH3 SCR system is a potential approach for controlling nitrogen oxides (NOX) emissions from lean burn gasoline engines. In this system, NH3 is generated over a close-coupled TWC during periodic slightly-rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst.more » Adding a NOX storage component to a TWC provides two benefits in the context of a passive SCR system: (1) enabling longer lean operation by storing NOX upstream and preserving NH3 inventory on the downstream SCR catalyst; and (2) increasing the quantity and rate of NH3 production during rich operation. Since the fuel penalty associated with passive SCR NOX control depends on the fraction of time that the engine is running rich rather than lean, both benefits (longer lean times and shorter rich times achieved via improved NH3 production) will decrease the passive SCR fuel penalty. However, these benefits are primarily realized at low to moderate temperatures (300-500 °C), where the NOX storage component is able to store NOX, with little to no benefit at higher temperatures (>500 °C), where NOX storage is no longer effective. This study discusses engine parameters and control strategies affecting the NH3 generation over a TWC with NOX storage component.« less
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Sobolevskiy, Anatoly [Orlando, FL; Rossin, Joseph A [Columbus, OH; Knapke, Michael J [Columbus, OH
2011-07-12
A process for the catalytic reduction of nitrogen oxides (NOx) in a gas stream (29) in the presence of H.sub.2 is provided. The process comprises contacting the gas stream with a catalyst system (38) comprising zirconia-silica washcoat particles (41), a pre-sulfated zirconia binder (44), and a catalyst combination (40) comprising palladium and at least one of rhodium, ruthenium, or a mixture of ruthenium and rhodium.
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Self-Protection Mechanism of Hexagonal WO3-Based DeNOx Catalysts against Alkali Poisoning.
Zheng, Li; Zhou, Meijuan; Huang, Zhiwei; Chen, Yaxin; Gao, Jiayi; Ma, Zhen; Chen, Jianmin; Tang, Xingfu
2016-11-01
A good catalyst for efficiently controlling NO x emissions often demands strong resistance against alkali poisoning. Although the traditional ion-exchange model, based on acid-base reactions of alkalis with Brønsted acid sites, has been established over the past two decades, it is difficult to be used as a guideline to develop such an alkali-resistant catalyst. Here we establish a self-protection mechanism of deNO x catalysts against alkali poisoning by systematically studying the intrinsic nature of alkali resistance of V 2 O 5 /HWO (HWO = hexagonal WO 3 ) that shows excellent resistance to alkali poisoning in selective catalytic reduction of NO x with NH 3 (SCR). Synchrotron X-ray diffraction and absorption spectroscopies demonstrate that V 2 O 5 /HWO has spatially separated catalytically active sites (CASs) and alkali-trapping sites (ATSs). During the SCR process, ATSs spontaneously trap alkali ions such as K + , even if alkali ions initially block CASs, thus releasing CASs to realize the self-protection against alkali poisoning. X-ray photoelectron spectra coupled with theoretical calculations indicate that the electronic interaction between the alkali ions and ATSs with an energy saving is the driving force of the self-protection. This work provides a strategy to design alkali-resistant deNO x catalysts.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, Do Heui; Kwak, Ja Hun; Szanyi, Janos
2008-02-28
The roles of barium oxide and platinum during the sulfation of Pt-BaO/Al2O3 lean NOx trap catalysts were investigated by S K edge XANES (X-ray absorption near-edge spectroscopy) and Pt LIII XAFS (X-ray absorption fine structure). All of the samples studied (Al2O3, BaO/Al2O3, Pt/Al2O3 and Pt-BaO/Al2O3) were pre-sulfated prior to the X-ray absorption measurements. It was found that barium oxide itself has the ability to directly form barium sulfate even in the absence of Pt and gas phase oxygen. In the platinum-containing samples, the presence of Pt-O species plays an important role in the formation of sulfate species. Even if bariummore » and aluminum sites are available for SO2 to form sulfate, for the case of the BaO(8)/Al2O3 sample, where the barium coverage is about 0.26 ML, S XANES spectroscopy results show that barium sulfates are preferentially produced over aluminum sulfates . When oxygen is absent from the gas phase, the sulfation route that involves Pt-O is eliminated after the initially present Pt-O species are completely consumed. In this case, formation of sulfates is suppressed unless barium oxide is also present. Pt LIII XAFS results show that the first coordination sphere around the Pt atoms in the Pt particles is dependent upon the redox nature of the gas mixture used during the sulfation process. Sulfation under reducing environments (e.g. SO2+H2) leads to formation of Pt-S bonds, while oxidizing conditions (e.g. SO2+O2) continue to show the presence of Pt-O bonds. In addition, the former condition was found to give rise to a higher degree of Pt sintering than the latter one. This result explains why samples sulfated under reducing conditions had lower NOx uptakes than those sulfated under oxidizing conditions. Therefore, our results provide needed information for the development of optimum practical operation conditions (e.g. sulfation or desulfation) for lean NOx trap catalysts that minimize deactivation by sulfur.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim,D.; Kwak, J.; Szanyi, J.
2008-01-01
The roles of barium oxide and platinum during the sulfation of Pt-BaO/Al2O3 lean NOx trap catalysts were investigated by S K edge XANES (X-ray absorption near-edge spectroscopy) and Pt LIII XAFS (X-ray absorption fine structure). All of the samples studied [Al2O3, BaO(x; x = 8 or 20 wt %)/Al2O3, Pt(2.5 wt %)/Al2O3, and Pt(2 wt %)-BaO(x; x = 8 or 20 wt %)/Al2O3] were pre-sulfated prior to the X-ray absorption measurements. It was found that barium oxide itself has the ability to directly form barium sulfate even in the absence of Pt and gas-phase oxygen. In the platinum-containing samples, themore » presence of Pt-O species plays an important role in the formation of sulfate species. For the case of the BaO(8)/Al2O3 sample, where the barium coverage is about 0.26 ML, both baria and alumina phases are available for sulfation. S XANES results show that barium sulfates are formed preferentially over aluminum sulfates. When oxygen is absent from the gas phase, the sulfation route that involves Pt-O is eliminated after the initially present Pt-O species are completely consumed. In this case, formation of sulfates is suppressed unless barium oxide is also present. Pt LIII XAFS results show that the first coordination sphere around the Pt atoms in the Pt particles is dependent upon the gas mixture used during the sulfation process. Sulfation under reducing environments (e.g., SO2/H2) leads to formation of Pt-S bonds, while oxidizing conditions (e.g., SO2/O2) continue to show the presence of Pt-O bonds. In addition, a reducing environment was found to cause Pt sintering in greater extent than an oxidizing one. This result explains why samples sulfated under reducing conditions had lower NOx uptakes than those sulfated under oxidizing conditions. Therefore, our results provide needed information for the development of optimum practical operation conditions (e.g., sulfation or desulfation) for lean NOx trap catalysts that minimize deactivation by sulfur.« less
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NASA Astrophysics Data System (ADS)
Xiong, Zhi-bo; Liu, Jing; Zhou, Fei; Liu, Dun-yu; Lu, Wei; Jin, Jing; Ding, Shi-fa
2017-06-01
A series of magnetic Fe0.85Ce0.10W0.05Oz catalysts were synthesized by three different methods(Co-precipitation(Fe0.85Ce0.10W0.05Oz-CP), Hydrothermal treatment assistant critic acid sol-gel method(Fe0.85Ce0.10W0.05Oz-HT) and Microwave irradiation assistant critic acid sol-gel method(Fe0.85Ce0.10W0.05Oz-MW)), and the catalytic activity was evaluated for selective catalytic reduction of NO with NH3. The catalyst was characterized by XRD, N2 adsorption-desorption, XPS, H2-TPR and NH3-TPD. Among the tested catalysts, Fe0.85Ce0.10W0.05Oz-MW shows the highest NOx conversion over per gram in unit time with NOx conversion of 60.8% at 350 °C under a high gas hourly space velocity of 1,200,000 ml/(g h). Different from Fe0.85Ce0.10W0.05Oz-CP catalyst, there exists a large of iron oxide crystallite(γ-Fe2O3 and α-Fe2O3) scattered in Fe0.85Ce0.10W0.05Oz catalysts prepared through hydrothermal treatment or microwave irradiation assistant critic acid sol-gel method, and higher iron atomic concentration on their surface. And Fe0.85Ce0.10W0.05Oz-MW shows higher surface absorbed oxygen concentration and better dispersion compared with Fe0.85Ce0.10W0.05Oz-HT catalyst. These features were favorable for the high catalytic performance of NO reduction with NH3 over Fe0.85Ce0.10W0.05Oz-MW catalyst.
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Sustained Low Temperature NOx Reduction
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zha, Yuhui
Increasing regulatory, environmental, and customer pressure in recent years led to substantial improvements in the fuel efficiency of diesel engines, including the remarkable breakthroughs demonstrated through the Super Truck program supported by the U.S. Department of Energy (DOE). On the other hand, these improvements have translated into a reduction of exhaust gas temperatures, thus further complicating the task of controlling NOx emissions, especially in low power duty cycles. The need for improved NOx conversion over these low temperature duty cycles is also observed as requirements tighten with in-use emissions testing. Sustained NOx reduction at low temperatures, especially in the 150-200oCmore » range, shares some similarities with the more commonly discussed cold-start challenge, however poses a number of additional and distinct technical problems. In this project we set a bold target of achieving and maintaining a 90% NOx conversion at the SCR catalyst inlet temperature of 150oC. The project is intended to push the boundaries of the existing technologies, while staying within the realm of realistic future practical implementation. In order to meet the resulting challenges at the levels of catalyst fundamentals, system components, and system integration, Cummins has partnered with the DOE, Johnson Matthey, and Pacific Northwest National Lab and initiated the Sustained Low-Temperature NOx Reduction program at the beginning of 2015. Through this collaboration, we are exploring catalyst formulations and catalyst architectures with enhanced catalytic activity at 150°C; opportunities to approach the desirable ratio of NO and NO2 in the SCR feed gas; options for robust low-temperature reductant delivery; and the requirements for overall system integration. The program is expected to deliver an on-engine demonstration of the technical solution and an assessment of its commercial potential. In the SAE meeting, we will share the initial performance data on
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Lean NOx catalysis for gasoline fueled European cars
DOE Office of Scientific and Technical Information (OSTI.GOV)
NONE
1997-02-01
There is increasing interest in operating gasoline fueled passenger cars lean of the stoichiometric air/fuel (A/F) ratio to improve fuel economy. These types of engines will operate at lean A/F ratios while cruising at partial load, and return to stoichiometric or even rich conditions when more power is required. The challenge for the engine and catalyst manufacturer is to develop a system which will combine the high activity rates of a state-of-the-art three-way catalyst (TWC) with the ability to reduce nitrogen oxides (NOx) in the presence of excess oxygen. The objective is to achieve the future legislative limits (EURO III/IV)more » in the European Union. Recent developments in automotive pollution control catalysis show that the use of NOx adsorption materials is a suitable way to reduce NOx emissions of gasoline-fueled lean-burn engines. However, the primary task for the implementation of this technology in the European market will be to improve the catalyst`s high-temperature stability and to decrease its susceptibility to sulfur poisoning. Outlined here are results of a recent R and D program to achieve NOx reduction under lean-burn gasoline engine conditions. Model gas test results as well as engine bench data are used for discussion of the parameters which control NOx adsorption efficiency under various conditions.« less
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Yang, Linyan; Lin, Siyu; Yang, Xue; Fang, Weimin; Zhou, Renxian
2014-08-30
The influence of alkaline earth metal (M=Mg, Ca, Sr and Ba) promoter on the structural/textural properties of Ce0.67Zr0.33O2 (designated as CZ) and the catalytic behavior of its supported Pd-only three-way catalyst (Pd/CZM) have been investigated. The results show that the modification with alkaline earth metal obviously improves the catalytic activity for hydrocarbon (HC) and nitrogen oxides (NOx) conversion, especially the introduction of Ba. Furthermore, the operation window of the promoted catalysts has also been widened. The doping of alkaline earth metal leads to the formation of more homogeneous Ce-Zr-M ternary solid solution with higher surface area and smaller crystallite size, and the corresponding Pd/CZM catalysts present improved reducibility of PdO species. The modification with Ca, Sr and Ba improves the thermal aging resistance, especially Ba. DRIFTS results reveal that the doping of alkaline earth metal enhances the oxygen and electron transfer ability and favors the dissociation of NO, which promotes the activation and storage capacity of the acidic atoms like NOx, and leads to enhanced catalytic activity performance. Copyright © 2014 Elsevier B.V. All rights reserved.
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Oh, Kwang Seok; Woo, Seong Ihl
2011-01-01
A chemiluminescence-based analyzer of NOx gas species has been applied for high-throughput screening of a library of catalytic materials. The applicability of the commercial NOx analyzer as a rapid screening tool was evaluated using selective catalytic reduction of NO gas. A library of 60 binary alloys composed of Pt and Co, Zr, La, Ce, Fe or W on Al2O3 substrate was tested for the efficiency of NOx removal using a home-built 64-channel parallel and sequential tubular reactor. The NOx concentrations measured by the NOx analyzer agreed well with the results obtained using micro gas chromatography for a reference catalyst consisting of 1 wt% Pt on γ-Al2O3. Most alloys showed high efficiency at 275 °C, which is typical of Pt-based catalysts for selective catalytic reduction of NO. The screening with NOx analyzer allowed to select Pt-Ce(X) (X=1–3) and Pt–Fe(2) as the optimal catalysts for NOx removal: 73% NOx conversion was achieved with the Pt–Fe(2) alloy, which was much better than the results for the reference catalyst and the other library alloys. This study demonstrates a sequential high-throughput method of practical evaluation of catalysts for the selective reduction of NO. PMID:27877438
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CuO based catalysts on modified acidic silica supports tested in the de-NOx reduction.
Bennici, Simona; Gervasini, Antonella; Lazzarin, Marta; Ragaini, Vittorio
2005-03-01
A series of dispersed CuO catalysts supported on modified silica supports with Al2O3 (SA), TiO2 (ST), and ZrO2 (SZ) were prepared optimising the adsorption method of copper deposition assisted by ultrasound treatment, already reported in a previous paper (S. Bennici, A. Gervasini, V. Ragaini, Ultrason. Sonochem. 10 (2003) 61). The obtained catalysts were characterized in their bulk (atomic absorption, X-ray diffraction, temperature programmed reduction) and surface (N2 adsorption, X-ray photoelectron spectroscopy, scanning electron microscopy) properties. The morphology of the finished materials was not deeply modified compared with that of the relevant supports. The employed complemented techniques evidenced a well dispersed CuO phase with a copper-support interaction on the most acidic supports (SA and SZ). The catalyst performances were studied in the reaction of selective catalytic reduction of NOx with ethene in oxidizing atmosphere in a flow apparatus under variable times (0.360-0.072 s) and temperatures (200-450 degrees C). The catalysts prepared on the most acidic supports (SA and SZ) were the most active and selective towards N2 formation. They showed a particular interesting activity in the reaction of NO2 reduction besides that of NO reduction.
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Method of preparing doped oxide catalysts for lean NOx exhaust
Park, Paul W.
2004-03-09
The lean NOx catalyst includes a substrate, an oxide support material, preferably .gamma.-alumina deposited on the substrate and a metal or metal oxide promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium cerium, and vanadium, and oxides thereof, and any combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between 80 and 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to about 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton
A comparative study was carried out on a small-pore CHA.Cu and a large-pore BEA.Cu zeolite catalyst to understand the lower N2O formation on small-pore zeolite supported Cu catalysts in the selective catalytic reduction (SCR) of NOx with NH3. On both catalysts, the N2O yield increases with an increase in the NO2/NOx ratios of the feed gas, suggesting N2O formation via the decomposition of NH4NO3. Temperature-programmed desorption experiments reveal that NH4NO3 is more stable on CHA.Cu than on BEA.Cu. In situ FTIR spectra following stepwise (NO2 + O2) and (15NO + NH3 + O2) adsorption and reaction, and product distribution analysismore » using isotope-labelled reactants, unambiguously prove that surface nitrate groups are essential for the formation of NH4NO3. Furthermore, CHA.Cu is shown to be considerably less active than BEA.Cu in catalyzing NO oxidation and the subsequent formation of surface nitrate groups. Both factors, i.e., (1) the higher thermal stability of NH4NO3 on CHA.Cu, and (2) the lower activity for this catalyst to catalyze NO oxidation and the subsequent formation of surface nitrates, likely contribute to the higher SCR selectivity with less N2O formation on this catalyst as compared to BEA.Cu. The latter is determined as the primary reason since surface nitrates are the source that leads to the formation of NH4NO3 on the catalysts.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Fang, Howard L.; Wang, Jerry C.; Yu, Robert C.
Sulfur poisoning from engine fuel and lube is one of the most recognizable degradation mechanisms of a NOx adsorber catalyst system for diesel emission reduction. Even with the availability of 15 ppm sulfur diesel fuel, NOx adsorber will be deactivated without an effective sulfur management. Two general pathways are currently being explored for sulfur management: (1) the use of a disposable SOx trap that can be replaced or rejuvenated offline periodically, and (2) the use of diesel fuel injection in the exhaust and high temperature de-sulfation approach to remove the sulfur poisons to recover the NOx trapping efficiency. The majormore » concern of the de-sulfation process is the many prolonged high temperature rich cycles that catalyst will encounter during its useful life. It is shown that NOx adsorber catalyst suffers some loss of its trapping capacity upon high temperature lean-rich exposure. With the use of a disposable SOx trap to remove large portion of the sulfur poisons from the exhaust, the NOx adsorber catalyst can be protected and the numbers of de-sulfation events can be greatly reduced. Spectroscopic techniques, such as DRIFTS and Raman, have been used to monitor the underlying chemical reactions during NOx trapping/ regeneration and de-sulfation periods, and provide a fundamental understanding of NOx storage capacity and catalyst degradation mechanism using model catalysts. This paper examines the sulfur effect on two model NOx adsorber catalysts. The chemistry of SOx/base metal oxides and the sulfation product pathways and their corresponding spectroscopic data are discussed. SAE Paper SAE-2003-01-3245 {copyright} 2003 SAE International. This paper is published on this website with permission from SAE International. As a user of this website, you are permitted to view this paper on-line, download this pdf file and print one copy of this paper at no cost for your use only. The downloaded pdf file and printout of this SAE paper may not be copied
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Investigation of NOx Removal from Small Engine Exhaust
NASA Technical Reports Server (NTRS)
Akyurtlu, Ates; Akyurtlu, Jale F.
1999-01-01
Contribution of emissions from small engines to the air pollution is significant. Due to differences in operating conditions and economics, the pollution control systems designed for automobiles will be neither suitable nor economically feasible for use on small engines. The objective of this project was to find a catalyst for the removal of NOx from the exhaust of small engines which use a rich air to fuel ratio. The desired catalyst should be inexpensive so that the cost of the pollution control unit will be only a small fraction of the total equipment cost. The high cost of noble metals makes them too expensive for use as NOx catalyst for small engines. Catalytic reduction of Nitrogen Oxide (NO) can also be accomplished by base-metal oxide catalysts. The main disadvantage of base-metal catalysts is their deactivation by poisons and high temperatures. Requirements for the length of the life of the small engine exhaust catalysts are much less than those for automobile exhaust catalysts. Since there is no oxygen in the exhaust gases, reduction selectivity is not a problem. Also, the reducing exhaust gases might help prevent the harmful interactions of the catalyst with the support. For these reasons only the supported metal oxide catalysts were investigated in this project.
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NOx reduction by electron beam-produced nitrogen atom injection
Penetrante, Bernardino M.
2002-01-01
Deactivated atomic nitrogen generated by an electron beam from a gas stream containing more than 99% N.sub.2 is injected at low temperatures into an engine exhaust to reduce NOx emissions. High NOx reduction efficiency is achieved with compact electron beam devices without use of a catalyst.
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Investigation of NO(x) Removal from Small Engine Exhaust
NASA Technical Reports Server (NTRS)
Akyurtlu, Ates; Akyurtlu, Jale F.
1999-01-01
Contribution of emissions from small engines to the air pollution is significant. Due to differences in operating conditions and economics, the pollution control systems designed for automobiles will be neither suitable nor economically feasible for use on small engines. The objective of this project was to find a catalyst for the removal of NOx from the exhaust of small engines which use a rich air to fuel ratio. The desired catalyst should be inexpensive so that the cost of the pollution control unit will be only a small fraction of the total equipment cost. The high cost of noble metals makes them too expensive for use as NOx catalyst for small engines. Catalytic reduction of NO can also be accomplished by base-metal oxide catalysts. The main disadvantage of base-metal catalysts is their deactivation by poisons and high temperatures. Requirements for the length of the life of the small engine exhaust catalysts are much less than those for automobile exhaust catalysts. Since there is no oxygen in the exhaust gases, reduction selectivity is not a problem. Also, the reducing exhaust gases might help prevent the harmful interactions of the catalyst with the support. For these reasons only the supported metal oxide catalysts were investigated in this project.
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Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials
DOE Office of Scientific and Technical Information (OSTI.GOV)
Beale, Andrew M.; Gao, Feng; Lezcano-Gonzalez, Ines
The ever increasing demand to develop highly fuel efficient engines coincides with the need to minimize air pollution originating from the exhaust gases of internal combustion engines. Dramatically improved fuel efficiency can be achieved at air-to-fuel ratios much higher than stoichiometric. In the presence of oxygen in large excess, however, traditional three-way catalysts are unable to reduce NOx. Among the number of lean-NOx reduction technologies, selective catalytic reduction (SCR) of NOx by NH3 over Cu- and Fe-ion exchanged zeolite catalysts has been extensively studied over the past 30+ years. Despite the significant advances in developing a viable practical zeolite-based catalystmore » for lean NOx reduction, the insufficient hydrothermal stabilities of the zeolite structures considered cast doubts about their real-world applicability. During the past decade a renewed interest in zeolite-based lean NOx reduction was spurred by the discovery of the very high activity of Cu-SSZ-13 (and the isostructural Cu-SAPO-34) in the NH3 SCR of NOx. These new, small-pore zeolite-based catalysts not only exhibited very high NOx conversion and N2 selectivity, but also exhibited exceptional high hydrothermal stability at high temperatures. In this review we summarize the key discoveries of the past ~5 years that lead to the introduction of these catalysts into practical application. The review first briefly discusses the structure and preparation of the CHA structure-based zeolite catalysts, and then summarizes the key learnings of the rather extensive (but not complete) characterisation work. Then we summarize the key findings of reaction kinetics studies, and provide some mechanistic details emerging from these investigations. At the end of the review we highlight some of the issues that are still need to be addressed in automotive exhaust control catalysis. Funding A.M.B. and I.L.G. would like to thank EPSRC for funding. F.G., C.H.F.P. and J.Sz. gratefully acknowledge
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di Lena, Fabio; Matyjaszewski, Krzysztof
2009-11-07
An electrospray ionization mass spectrometer equipped with a quadrupole ion trap as the mass analyzer provided a powerful tool for the investigation of metal ligand affinities of catalysts for atom transfer radical polymerization. It allowed, in particular, (i) the identification, in a library of ligands, of the most stable, and thus active, copper catalysts; (ii) the assessment of the effects of the reaction medium on the relative stabilities of the catalyst complexes; and (iii) the evaluation of the influence of the nature of the ligand on both the complex halogenophilicity and the metal-ligand stabilities in the gas-phase.
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Commercialization of the Chevron FCC vanadium trap
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kennedy, J.V.; Kuehler, C.W.; Krishna, A.S.
1995-09-01
Vanadium, present to varying degrees in FCC feed, deposits on the catalyst virtually quantitatively in the cracking process. In resid operations, vanadium levels on catalyst can reach 10,000 ppm at typical catalyst make-up rates. Once on the catalyst, vanadium destroys the zeolite and restricts access to active sites. This reduces catalyst activity. A vanadium trap is a material that when introduced into the catalyst inventory selectively reacts with migrating vanadium, thus protecting the zeolite and other active components of the catalyst. The trap may be incorporated into the catalyst, or introduced as a separate particle. Only a limited amount ofmore » trap can be incorporated into the catalyst without limiting the amount of zeolite that can be included. Gulf began development of a vanadium trap during the early 1980`s. The work produced a variety of promising materials whose use as vanadium traps was subsequently patented. The work ultimately led to a formulation with a phase very active for trapping vanadium while still quite sulfur tolerant. Based on these results, an extensive pilot plant evaluation was undertaken by Chevron after the Chevron-Gulf merger to better simulate commercial operation. The paper describes pilot plant tests as well as 3 commercial tests of this vanadium trap.« less
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Investigation of Mixed Oxide Catalysts for NO Oxidation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Szanyi, Janos; Karim, Ayman M.; Pederson, Larry R.
2014-12-09
The oxidation of engine-generated NO to NO2 is an important step in the reduction of NOx in lean engine exhaust because NO2 is required for the performance of the LNT technology [2], and it enhances the activities of ammonia selective catalytic reduction (SCR) catalysts [1]. In particular, for SCR catalysts an NO:NO2 ratio of 1:1 is most effective for NOx reduction, whereas for LNT catalysts, NO must be oxidized to NO2 before adsorption on the storage components. However, NO2 typically constitutes less than 10% of NOx in lean exhaust, so catalytic oxidation of NO is essential. Platinum has been foundmore » to be especially active for NO oxidation, and is widely used in DOC and LNT catalysts. However, because of the high cost and poor thermal durability of Pt-based catalysts, there is substantial interest in the development of alternatives. The objective of this project, in collaboration with partner General Motors, is to develop mixed metal oxide catalysts for NO oxidation, enabling lower precious metal usage in emission control systems. [1] M. Koebel, G. Madia, and M. Elsener, Catalysis Today 73, 239 (2002). [2] C. H. Kim, G. S. Qi, K. Dahlberg, and W. Li, Science 327, 1624 (2010).« less
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NOx Binding and Dissociation: Enhanced Ferroelectric Surface Chemistry by Catalytic Monolayers
NASA Astrophysics Data System (ADS)
Kakekhani, Arvin; Ismail-Beigi, Sohrab
2013-03-01
NOx molecules are regulated air pollutants produced during automotive combustion. As part of an effort to design viable catalysts for NOx decomposition operating at higher temperatures that would allow for improved fuel efficiency, we examine NOx chemistry on ferroelectric perovskite surfaces. Changing the direction of ferroelectric polarization can modify surface electronic properties and may lead to switchable surface chemistry. Here, we describe our recent work on potentially enhanced surface chemistry using catalytic RuO2 monolayers on perovskite ferroelectric substrates. In addition to thermodynamic stabilization of the RuO2 layer, we present results on the polarization-dependent binding of NO, O2, N2, and atomic O and N. We present results showing that one key problem with current catalysts, involving the difficulty of releasing dissociation products (especially oxygen), can be ameliorated by this method. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.
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Plasma and catalyst for the oxidation of NOx
NASA Astrophysics Data System (ADS)
Jõgi, Indrek; Erme, Kalev; Levoll, Erik; Raud, Jüri; Stamate, Eugen
2018-03-01
Efficient exhaust gas cleaning from NO x (NO and NO2) by absorption and adsorption based methods requires the oxidation of NO. The application of non-thermal plasma is considered as a promising oxidation method but the oxidation of NO by direct plasma remains limited due to the back-reaction of NO2 to NO mediated by O radicals in plasma. Indirect NO oxidation by plasma produced ozone allows to circumvent the back-reaction and further oxidize NO2 to N2O5 but the slow reaction rate for the latter process limits the efficiency of this process. Present paper gives an overview of the role of metal-oxide catalysts in the improvement of oxidation efficiency for both direct and indirect plasma oxidation of NO x . The plasma produced active oxygen species (O, O3) were shown to play an important role in the reactions taking place on the catalyst surfaces while the exact mechanism and extent of the effect were different for direct and indirect oxidation. In the case of direct plasma oxidation, both short and long lifetime oxygen species could reach the catalyst and participate in the oxidation of NO to NO2. The back-reaction in the plasma phase remained still important factor and limited the effect of catalyst. In the case of indirect oxidation, only ozone could reach the catalyst surface and improve the oxidation of NO2 to N2O5. The effect of catalyst at different experimental conditions was quantitatively described with the aid of simple global chemical kinetic models derived for the NO x oxidation either by plasma or ozone. The models allowed to compare the effect of different catalysts and to analyze the limitations for the efficiency improvement by catalyst.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, Do Heui; Szanyi, Janos; Kwak, Ja Hun
2009-04-03
Desulfation by hydrogen of pre-sulfated Pt(2wt%) BaO(20wt%)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31 and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), x-ray photoelectron spectroscopy (XPS), in-situ sulfur K-edge x-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved x-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in-situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phase and remained in the catalyst, rathermore » than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H2O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H2S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt BaO/Al2O3 lean NOx trap catalysts is markedly dependent on the sulfation levels.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Szanyi, Janos; Yi, Cheol-Woo W.; Mudiyanselage, Kumudu K.
2013-11-01
The structure-reactivity relationships of model BaO-based NOx storage/reduction catalysts were investigated under well controlled experimental conditions using surface science analysis techniques. The reactivity of BaO toward NO2, CO2, and H2O was studied as a function of BaO layer thickness [0\\hBaO\\30 monolayer (ML)], sample temperature, reactant partial pressure, and the nature of the substrate the NOx storage material was deposited onto. Most of the efforts focused on understanding the mechanism of NO2 storage either on pure BaO, or on BaO exposed to CO2 or H2O prior to NO2 exposure. The interaction of NO2 with a pure BaO film results in themore » initial formation of nitrite/nitrate ion pairs by a cooperative adsorption mechanism predicted by prior theoretical calculations. The nitrites are then further oxidized to nitrates to produce a fully nitrated surface. The mechanism of NO2 uptake on thin BaO films (\\4 ML), BaO clusters (\\1 ML) and mixed BaO/Al2O3 layers are fundamentally different: in these systems initially nitrites are formed only, and then converted to nitrates at longer NO2 exposure times. These results clarify the contradicting mechanisms presented in prior studies in the literature. After the formation of a nitrate layer the further conversion of the underlying BaO is slow, and strongly depends on both the sample temperature and the NO2 partial pressure. At 300 K sample temperature amorphous Ba(NO3)2 forms that then can be converted to crystalline nitrates at elevated temperatures. The reaction between BaO and H2O is facile, a series of Ba(OH)2 phases form under the temperature and H2O partial pressure regimes studied. Both amorphous and crystalline Ba(OH)2 phases react with NO2, and initially form nitrites only that can be converted to nitrates. The NO2 adsorption capacities of BaO and Ba(OH)2 are identical, i.e., both of these phases can completely be converted to Ba(NO3)2. In contrast, the interaction of CO2 with pure BaO results in the
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Reformer assisted lean NO.sub.x catalyst aftertreatment system and method
Kalyanaraman, Mohan [Media, PA; Park, Paul W [Peoria, IL; Ragle, Christie S [Havana, IL
2010-06-29
A method and apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NO.sub.x therein, wherein the apparatus includes a first catalyst composed of a silver-containing alumina that is adapted for catalytically processing the gas stream at a first temperature range, a second catalyst composed of a copper-containing zeolite located downstream from the first catalyst, wherein the second catalyst is adapted for catalytically processing the gas stream at a lower second temperature range relative to the first temperature range, a hydrocarbon compound for injection into the gas stream upstream of the first catalyst to provide a reductant, and a reformer for reforming a portion of the hydrocarbon compound into H.sub.2 and/or oxygenated hydrocarbon for injection into the gas stream upstream of the first catalyst. The second catalyst is adapted to facilitate the reaction of reducing NOx into N.sub.2, whereby the intermediates are produced via the first catalyst reacting with NOx and hydrocarbons.
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Shi, Xiaoyan; Yu, Yunbo; He, Hong; Shuai, Shijin; Dong, Hongyi; Li, Rulong
2008-01-01
In this study, the efforts to reduce NOx and particulate matter (PM) emissions from a diesel engine using both ethanol-selective catalytic reduction (SCR) of NOx over an Ag/Al2O3 catalyst and a biodiesel-ethanol-diesel fuel blend (BE-diesel) on an engine bench test are discussed. Compared with diesel fuel, use of BE-diesel increased PM emissions by 14% due to the increase in the soluble organic fraction (SOF) of PM, but it greatly reduced the Bosch smoke number by 60%-80% according to the results from 13-mode test of European Stationary Cycle (ESC) test. The SCR catalyst was effective in NOx reduction by ethanol, and the NOx conversion was approximately 73%. Total hydrocarbons (THC) and CO emissions increased significantly during the SCR of NOx process. Two diesel oxidation catalyst (DOC) assemblies were used after Ag/Al2O3 converter to remove CO and HC. Different oxidation catalyst showed opposite effect on PM emission. The PM composition analysis revealed that the net effect of oxidation catalyst on total PM was an integrative effect on SOF reduction and sulfate formation of PM. The engine bench test results indicated that the combination of BE-diesel and a SCR catalyst assembly could provide benefits for NOx and PM emissions control even without using diesel particle filters (DPFs).
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Process of activation of a palladium catalyst system
Sobolevskiy, Anatoly [Orlando, FL; Rossin, Joseph A [Columbus, OH; Knapke, Michael J [Columbus, OH
2011-08-02
Improved processes for activating a catalyst system used for the reduction of nitrogen oxides are provided. In one embodiment, the catalyst system is activated by passing an activation gas stream having an amount of each of oxygen, water vapor, nitrogen oxides, and hydrogen over the catalyst system and increasing a temperature of the catalyst system to a temperature of at least 180.degree. C. at a heating rate of from 1-20.degree./min. Use of activation processes described herein leads to a catalyst system with superior NOx reduction capabilities.
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Novel Co- or Ni-Mn binary oxide catalysts with hydroxyl groups for NH3-SCR of NOx at low temperature
NASA Astrophysics Data System (ADS)
Gao, Fengyu; Tang, Xiaolong; Yi, Honghong; Zhao, Shunzheng; Wang, Jiangen; Shi, Yiran; Meng, Xiaomi
2018-06-01
Novel hydroxyl-containing Me-Mn binary oxides (Me = Co, Ni) were prepared for the selective catalytic reduction of NOx with NH3 by a combined complexation-esterification method. The binary oxides of Co-MnOx and Ni-MnOx with mixed crystal phases of Mn3O4 and Co3O4, Mn2O3 and NiMnO3 were obtained at 550 °C. SCR activity decreased in the order of Mn3O4-Co3O4-OH > Mn2O3-NiMnO3-OH > Mn2O3-OH > Mn3O4-OH, benefiting from the high concentration of chemisorbed oxygen and effective electron transformation of cations. Mn2O3-containing catalysts had better selectivity to N2 than those containing Mn3O4. Higher selectivity to N2O over Mn3O4-containing catalysts was attributed to the depth dehydrogenation of coordinated NH3 by the active oxygen species with lower Mnsbnd O band energy. The typical Eley-Rideal mechanism over Mn3O4-OH and Mn3O4-Co3O4-OH, and the additional formation pathway of NH4NO3 species over Mn2O3-OH and Mn2O3-NiMnO3-OH catalysts were proposed via the in-situ DRIFTS experiments. Although the Co and Ni elements had a good role in delaying the poisoning of SO2, these catalysts were eventually sulfated by SO2 over the postponement, which might due to the metal sulfate and ammonia hydrogensulfite species.
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Method for reducing NOx during combustion of coal in a burner
Zhou, Bing [Cranbury, NJ; Parasher, Sukesh [Lawrenceville, NJ; Hare, Jeffrey J [Provo, UT; Harding, N Stanley [North Salt Lake, UT; Black, Stephanie E [Sandy, UT; Johnson, Kenneth R [Highland, UT
2008-04-15
An organically complexed nanocatalyst composition is applied to or mixed with coal prior to or upon introducing the coal into a coal burner in order to catalyze the removal of coal nitrogen from the coal and its conversion into nitrogen gas prior to combustion of the coal. This process leads to reduced NOx production during coal combustion. The nanocatalyst compositions include a nanoparticle catalyst that is made using a dispersing agent that can bond with the catalyst atoms. The dispersing agent forms stable, dispersed, nano-sized catalyst particles. The catalyst composition can be formed as a stable suspension to facilitate storage, transportation and application of the catalyst nanoparticles to a coal material. The catalyst composition can be applied before or after pulverizing the coal material or it may be injected directly into the coal burner together with pulverized coal.
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Kinetic and spectroscopic study of catalysts for water-gas shift and nitrogen oxide removal
NASA Astrophysics Data System (ADS)
Kispersky, Vincent Frederick
Nitrogen oxides (NOx) are formed in high temperature combustion processes such as in power generation and motor vehicles. Increasingly stringent regulation of these harmful emissions continues to drive interest in developing, understanding and studying new catalytic formulations for exhaust aftertreatment. For mobile sources, predominantly heavy duty diesel engines, selective catalytic reduction (SCR) with NH3 has become the principal means of NO x abatement. An alternative technology developed, but now surpassed by SCR, is NOx Storage Reduction (NSR) catalysis. Both technologies have been studied in our laboratory and are the basis for this dissertation. We studied seven different lean NOx trap (LNT) monolith formulations for NSR ranging from 0.6 to 6.2 wt.% Pt and 4 to 20 wt.% Ba loadings on γ-Al 2O3. The noble metal component of a LNT oxidizes NO to NO 2 aiding in the storage of NO2 on the alkaline earth component. Before the storage component saturates, a reductant such as H2 is introduced into the vehicular exhaust and the stored NOx is released and reduced to N2. Once the storage component is free of NOx, reductant flow is ceased and storage is begun anew. Our research focused on understanding the effects that CO2 and H2O have on the storage capacity of the LNT over short as well as extended periods of time. We found that for high Ba loadings, CO 2 had a consistently detrimental effect on the fast NOx storage capacity (NSC), defined as the amount of NOx the catalyst can store before 1% of the inlet NOx is measured in the reactor outlet. Over long NOx storage periods, CO2 continued to inhibit storage compared to the same catalyst in CO2 free conditions. On low loadings of Ba, however, the inhibition of CO2 was significantly reduced. We found that the loading dependent characteristics of the Ba phase affected the way in which CO2 adsorbed on the storage component, which greatly affected the stability of the species on lower Ba loadings. The less stable
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2015-01-01
Efficient reduction of O2 to water is a central challenge in energy conversion and many aerobic oxidation reactions. Here, we show that the electrochemical oxygen reduction reaction (ORR) can be achieved at high potentials by using soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (TEMPO), nor NOx species, such as sodium nitrite, are effective ORR mediators. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction with overpotentials as low as 300 mV in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The overpotentials accessible with this ORR system are significantly lower than widely studied molecular metal-macrocycle ORR catalysts and benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. PMID:27162977
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Fornarelli, Francesco; Dadduzio, Ruggiero; Torresi, Marco; Camporeale, Sergio Mario; Fortunato, Bernardo
2018-02-01
A fully 3D unsteady Computational Fluid Dynamics (CFD) approach coupled with heterogeneous reaction chemistry is presented in order to study the behavior of a single square channel as part of a Lean [Formula: see text] Traps. The reliability of the numerical tool has been validated against literature data considering only active BaO site. Even though the input/output performance of such catalyst has been well known, here the spatial distribution within a single channel is investigated in details. The square channel geometry influences the flow field and the catalyst performance being the flow velocity distribution on the cross section non homogeneous. The mutual interaction between the flow and the active catalyst walls influences the spatial distribution of the volumetric species. Low velocity regions near the square corners and transversal secondary flows are shown in several cross-sections along the streamwise direction at different instants. The results shed light on the three-dimensional characteristic of both the flow field and species distribution within a single square channel of the catalyst with respect to 0-1D approaches.
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Recent Developments of Electrochemical Promotion of Catalysis in the Techniques of DeNOx
Tang, Xiaolong; Yi, Honghong; Chen, Chen; Wang, Chuan
2013-01-01
Electrochemical promotion of catalysis reactions (EPOC) is one of the most significant discoveries in the field of catalytic and environmental protection. The work presented in this paper focuses on the aspects of reaction mechanism, influencing factors, and recent positive results. It has been shown with more than 80 different catalytic systems that the catalytic activity and selectivity of conductive catalysts deposited on solid electrolytes can be altered in the last 30 years. The active ingredient of catalyst can be activated by applying constant voltage or constant current to the catalysts/electrolyte interface. The effect of EPOC can improve greatly the conversion rate of NOx. And it can also improve the lifetime of catalyst by inhibiting its poisoning. PMID:23970835
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NASA Astrophysics Data System (ADS)
Kakekhani, Arvin; Ismail-Beigi, Sohrab
2014-03-01
NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.
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Pilot-scale tests were conducted to develop a combined nitrogen oxide (NOx) reduction technology using both selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). A commercially available vanadium-and titatnium-based composite honeycomb catalyst and enh...
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Kuwahara, Takuya; Nakaguchi, Harunobu; Kuroki, Tomoyuki; Okubo, Masaaki
2016-05-05
Considering the recent stringent regulations governing diesel NO(x) emission, an aftertreatment system for the reduction of NO(x) in the exhaust gas has been proposed and studied. The proposed system is a hybrid method combining nonthermal plasma and NOx adsorbent. The system does not require precious metal catalysts or harmful chemicals such as urea and ammonia. In the present system, NO(x) in diesel emission is treated by adsorption and desorption by adsorbent as well as nonthermal plasma reduction. In addition, the remaining NO(x) in the adsorbent is desorbed again in the supplied air by residual heat. The desorbed NO(x) in air recirculates into the intake of the engine, and this process, i.e., exhaust gas components' recirculation (EGCR) achieves NO(x) reduction. Alternate utilization of two adsorption chambers in the system can achieve high-efficiency NO(x) removal continuously. An experiment with a stationary diesel engine for electric power generation demonstrates an energy efficiency of 154 g(NO2)/kWh for NO(x) removal and continuous NO(x) reduction of 70.3%. Considering the regulation against diesel emission in Japan, i.e., the new regulation to be imposed on vehicles of 3.5-7.5 ton since 2016, the present aftertreatment system fulfills the requirement with only 1.0% of engine power. Copyright © 2016. Published by Elsevier B.V.
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Ammonia reactions with the stored oxygen in a commercial lean NO x trap catalyst
Bartova, Sarka; Mracek, David; Koci, Petr; ...
2014-10-12
Ammonia is an important intermediate of the NO x reduction in a NO x storage and reduction catalyst (aka lean NO x trap). NH 3 formed under rich conditions in the reduced front part of the catalyst is transported by convection downstream to the unregenerated (still oxidized) zone of the catalyst, where it further reacts with the stored oxygen and NO x. In this paper, the kinetics and selectivity of NH 3 reactions with the stored oxygen are studied in detail with a commercial Ba-based NO x storage catalyst containing platinum group metals (PGM), Ba and Ce oxides. Furthermore, steady-statemore » NH 3 decomposition, NH 3 oxidation by O 2 and NO, and N 2O decomposition are examined in light-off experiments. Periodic lean/rich cycling is measured first with O 2 and NH 3, and then with NO x + O 2 and NH 3 to discriminate between the NH 3 reactions with the stored oxygen and the stored NO x. The reaction of NH 3 with the stored O 2 is highly selective towards N 2, however a certain amount of NO x and N 2O is also formed. The formed NO x by-product is efficiently adsorbed on the NO x storage sites such that the NO x is not detected at the reactor outlet except at high temperatures. The stored NO x reacts with NH 3 feed in the next rich phase, contributing to the N 2O formation. Water inhibits the reactions of NH 3 with the stored oxygen. On the contrary, the presence of CO 2 increases the NH 3 consumption. Furthermore, CO 2 is able to provide additional oxygen for NH 3 oxidation, forming –CO in analogy to the reverse water gas shift reaction.« less
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Yoon, Seungju; Collins, John; Thiruvengadam, Arvind; Gautam, Mridul; Herner, Jorn; Ayala, Alberto
2013-08-01
Engine and exhaust control technologies applied to compressed natural gas (CNG) transit buses have advanced from lean-burn, to lean-burn with oxidation catalyst (OxC), to stoichiometric combustion with three-way catalyst (TWC). With this technology advancement, regulated gaseous and particulate matter emissions have been significantly reduced. Two CNG transit buses equipped with stoichiometric combustion engines and TWCs were tested on a chassis dynamometer, and their emissions were measured. Emissions from the stoichiometric engines with TWCs were then compared to the emissions from lean-burn CNG transit buses tested in previous studies. Stoichiometric combustion with TWC was effective in reducing emissions of oxides of nitrogen (NO(x)), particulate matter (PM), and nonmethane hydrocarbon (NMHC) by 87% to 98% depending on pollutants and test cycles, compared to lean combustion. The high removal efficiencies exceeded the emission reduction required from the certification standards, especially for NO(x) and PM. While the certification standards require 95% and 90% reductions for NO(x) and PM, respectively, from the engine model years 1998-2003 to the engine model year 2007, the measured NO(x) and PM emissions show 96% and 95% reductions, respectively, from the lean-burn engines to the stoichiometric engines with TWC over the transient Urban Dynamometer Driving Schedule (UDDS) cycle. One drawback of stoichiometric combustion with TWC is that this technology produces higher carbon monoxide (CO) emissions than lean combustion. In regard to controlling CO emissions, lean combustion with OxC is more effective than stoichiometric combustion. Stoichiometric combustion with TWC produced higher greenhouse gas (GHG) emissions including carbon dioxide (CO2) and methane (CH4) than lean combustion during the UDDS cycle, but lower GHG emissions during the steady-state cruise cycle. Stoichiometric combustion with three-way catalyst is currently the best emission control technology
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NASA Astrophysics Data System (ADS)
Pourkhalil, Mahnaz; Moghaddam, Abdolsamad Zarringhalam; Rashidi, Alimorad; Towfighi, Jafar; Mortazavi, Yadollah
2013-08-01
Manganese oxide catalysts (MnOx) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by the incipient wetness impregnation method. These catalysts were characterized by N2 adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H2-temperature programmed reduction (H2-TPR) methods. The effects of reaction temperature, MnOx loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NOx with NH3. Under the reaction conditions of 200 °C, 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol%, GHSV = 30,000 h-1 and 12 wt% MnOx, NOx conversion and N2 selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO2 and 2.5 vol% H2O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.
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NASA Astrophysics Data System (ADS)
Cheng, Lin; Wang, Rui
2012-01-01
Surface-modified carbon nanotubes (CNTs) and nano-Ce-Zr mixed oxides (CZO) were prepared and employed initially as supports of H3PW12O40 (HPW) for NOx adsorption-decomposition. Both CNTs and nano-CZO are favorable supports for HPW. After loading with HPW, the NOx adsorption efficiency increases, especially for HPW/CZO in which the highest adsorption efficiency can achieve 98% at the HPW loading of 70%, much higher than that of single HPW. NOx adsorption efficiency can be influenced considerably by catalyst preparing conditions, in particularly, ethyl alcohol is superior to water as solvent for HPW loading onto CNTs; the -OH containing CNTs shows better promotion effect on the adsorption of NOx than that containing -COOH when using absolute ethyl alcohol as solvent; mechanical grinding method is superior to incipient impregnation method in loading HPW onto the support of CZO. For both catalysts of HPW/CNTs and HPW/CZO, with the increase of HPW loading, the NOx adsorption efficiency tends to reach a peak value before dropping down. Heated from 150°C to 450°C at a rate of 50°C/min, the adsorbed NO was found to decompose into N2, O2 and N2O, and yields of N2 being 21.8% and 27.3%, respectively for HPW/CNTs and HPW/CZO were obtained.
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Catalysts, systems and methods to reduce NOX in an exhaust gas stream
Castellano, Christopher R.; Moini, Ahmad; Koermer, Gerald S.; Furbeck, Howard
2010-07-20
Catalysts, systems and methods are described to reduce NO.sub.x emissions of an internal combustion engine. In one embodiment, an emissions treatment system for an exhaust stream is provided having an SCR catalyst comprising silver tungstate on an alumina support. The emissions treatment system may be used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines. An emissions treatment system may further comprise an injection device operative to dispense a hydrocarbon reducing agent upstream of the catalyst.
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Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf
2017-01-01
Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NOx emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH3) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH3 loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH3 storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH3 storage levels, and NH3 target curves. It could be clearly demonstrated that the right NH3 target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NOx conversion efficiency and without NH3 slip. PMID:29182589
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Composite TiO2/clays materials for photocatalytic NOx oxidation
NASA Astrophysics Data System (ADS)
Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D.; Vaimakis, T.; Trapalis, C.
2014-11-01
TiO2 photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO2 in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO2). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al3+ and Ca2+ intercalation was applied in order to improve the dispersion of TiO2 and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania under both types of irradiation. Significant visible light activity was recorded for the composites containing urea-modified titania that was accredited to the N-doping of the semiconductor. Among the different substrates, the hydrotalcite caused highest increase in the NOx removal, while among the intercalation ions the Ca2+ was more efficient. The results were related to the improved dispersion of the TiO2 and the synergetic activity of the substrates as NOx adsorbers.
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Chang, Huazhen; Wu, Qingru; Zhang, Tao; Li, Mingguan; Sun, Xiaoxu; Li, Junhua; Duan, Lei; Hao, Jiming
2015-10-20
A series of CeMoOx catalysts with different surface Ce/Mo ratios was synthesized by a coprecipitation method via changing precipitation pH value. The surface basicity on selective catalytic reduction (SCR) catalysts (CeMoOx and VMo/Ti) was characterized and correlated to the durability and activity of catalyst for simultaneous elimination of NOx and Hg(0). The pH value in the preparation process affected the surface concentrations of Ce and Mo, the Brunauer-Emmett-Teller (BET) specific surface area, and the acid-base properties over the CeMoOx catalysts. The O 1s X-ray photoelectron spectroscopy (XPS) spectra and CO2-temperature programmed desorption (TPD) suggested that the surface basicity increased as the pH value increased. The existence of strong basic sites contributed to the deactivation effect of HCl over the VMo/Ti and CeMoOx catalysts prepared at pH = 12. For the CeMoOx catalysts prepared at pH = 9 and 6, the appearance of surface molybdena species replaced the surface -OH, and the existence of appropriate medium-strength basic sites contributed to their resistance to HCl poisoning in the SCR reaction. Moreover, these sites facilitated the adsorption and activation of HCl and enhanced Hg(0) oxidation. On the other hand, the inhibitory effect of NH3 on Hg(0) oxidation was correlated with the competitive adsorption of NH3 and Hg(0) on acidic surface sites. Therefore, acidic surface sites may play an important role in Hg(0) adsorption. The characterization and balance of basicity and acidity of an SCR catalyst is believed to be helpful in preventing deactivation by acid gas in the SCR reaction and simultaneous Hg(0) oxidation.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Toops, Todd J; Pihl, Josh A
2008-01-01
Exposure of Pt/K/Al{sub 2}O{sub 3} to 15 ppm SO{sub 2} reduces the NOx activity at 200, 300, and 400 C at significantly different rates--1.5, 8.5, and 18.0 {micro}mol NOx/(h g{sub cat}), respectively. During the initial sulfation, NOx conversion is directly linked to lean phase storage capacity, and sulfation does not impact the reduction kinetics since the amount of unconverted NOx was constant or decreased with increasing sulfation time. A portion of sulfur stored at 200 C desorbs upon mild heating to 400 C while cycling between lean and rich conditions. This apparently is a result of sulfur being released frommore » Al{sub 2}O{sub 3}; however, performance is not significantly recovered as much of the sulfur is re-adsorbed on the K-phase. This is apparent from analysis of the NOx storage and release profiles. Additional analysis of these profiles suggests that SO{sub 2} initially adsorbs near Pt before interacting with other sites further away from Pt at 300 C. At 400 C, it appears that SO{sub 2} either preferentially adsorbs near Pt and then quickly diffuses along the surface to other less proximal sites, or it directly adsorbs on sites further away from Pt. De-sulfurization up to 800 C using a temperature programmed reduction (TPR) procedure and rich conditions with both CO{sub 2} and H{sub 2}O restored 73=94% of the LNT performance at 300 and 400 C. However, the recovered performance measured at 200 C was only 34-49% of the original NOx reduction activity. H{sub 2}S and SO{sub 2} were the primary de-sulfurization products with H{sub 2}S having a maximum release between 690 and 755 C, while SO{sub 2} had a peak release between 770 and 785 C. The sulfation temperature does not have a significant impact on the recovered performance, the de-sulfurization products or the sulfur release temperature.« less
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Effect of water vapor on NH3-NO/NO2 SCR performance of fresh and aged MnOx-NbOx-CeO2 catalysts.
Chen, Lei; Si, Zhichun; Wu, Xiaodong; Weng, Duan; Wu, Zhenwei
2015-05-01
A MnOx-NbOx-CeO2 catalyst for low temperature selective catalytic reduction (SCR) of NOx with NH3 was prepared by a sol-gel method, and characterized by NH3-NO/NO2 SCR catalytic activity, NO/NH3 oxidation activity, NOx/NH3 TPD, XRD, BET, H2-TPR and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The results indicate that the MnOx-NbOx-CeO2 catalyst shows excellent low temperature NH3-SCR activity in the temperature range of 150-300°C. Water vapor inhibits the low temperature activity of the catalyst in standard SCR due to the inhibition of NOx adsorption. As the NO2 content increases in the feed, water vapor does not affect the activity in NO2 SCR. Meanwhile, water vapor significantly enhances the N2 selectivity of the fresh and the aged catalysts due to its inhibition of the decomposition of NH4NO3 into N2O. Copyright © 2015. Published by Elsevier B.V.
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Possible Catalytic Effects of Ice Particles on the Production of NOx by Lightning Discharges
NASA Technical Reports Server (NTRS)
2010-01-01
One mechanism by which NO(x) is produced in the atmosphere is heating in lightning discharge channels. Since most viable proposed electrification mechanisms involve ice crystals, it is reasonable to assume that lightning discharge channels frequently pass through fields of ice particles of various kinds. We address the question of whether ice crystals may serve as catalysts for the production of NO(x) by lightning discharges. If so, and if the effect is large, it would need to be taken into account in estimates of global NO(x) production by lightning. In this study, we make a series of plausible assumptions about the temperature and concentration of reactant species in the environment of discharges and we postulate a mechanism by which ice crystals are able to adsorb nitrogen atoms. We then compare production rates between uncatalyzed and catalytic reactions at 2000 K, 3000 K, and 4000 K. Catalyzed NO production rates are greater at 2000 K, whereas uncatalyzed production occurs most rapidly at 4000 K. 2010
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Study on the mechanism of a manganese-based catalyst for catalytic NOX flue gas denitration
NASA Astrophysics Data System (ADS)
Zhang, Lei; Wen, Xin; Lei, Zhang; Gao, Long; Sha, Xiangling; Ma, Zhenhua; He, Huibin; Wang, Yusu; Jia, Yang; Li, Yonghui
2018-04-01
Manganese-based bimetallic catalysts were prepared with self-made pyrolysis coke as carrier and its denitration performance of low-temperature SCR (selective catalyst reduction) was studied. The effects of different metal species, calcination temperature, calcination time and the metal load quantity on the denitration performance of the catalyst were studied by orthogonal test. The denitration mechanism of the catalyst was analyzed by XRD (X-ray diffraction), SEM (scanning electron microscope), BET test and transient test. The experiments show that: * The denitration efficiency of Mn-based bimetallic catalysts mainly relates to the metal type, the metal load quantity and the catalyst adjuvant type. * The optimal catalyst preparation conditions are as follows: the load quantity of monometallic MnO2 is 10%, calcined at 300°C for 4h, and then loaded with 8% CeO2, calcined at 350°Cfor 3h. * The denitration mechanism of manganese-based bimetallic oxide catalysts is stated as: NH3 is firstly adsorbed by B acid center Mn-OH which nears Mn4+==O to form NH4+, NH4+ was then attacked by the gas phase NO to form N2, H2O and Mn3+-OH. Finally, Mn3+-OH was oxidized by O2 to regenerate Mn4+.
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NASA Astrophysics Data System (ADS)
Kenagy, H. S.; Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Lopez-Hilfiker, F.; Lee, B. H.; Thornton, J. A.; McDuffie, E. E.; Fibiger, D. L.; Brown, S. S.; Montzka, D. D.; Weinheimer, A. J.; Apel, E. C.; Jaegle, L.; Cohen, R. C.
2017-12-01
The study of the lifetime and fate of NOx (=NO + NO2) is important for understanding its persistence and distribution. This requires an understanding of the balance of NOx sinks. Although urban NOx lifetimes are relatively well understood during summertime conditions, wintertime NOx chemistry has been comparatively less studied. We used measurements of NOx and its oxidation products from the aircraft-based WINTER (Wintertime INvestigation of Transport, Emissions, and Reactivity) campaign over the northeastern US during February-March 2015 to help constrain NOx lifetime during wintertime conditions when days are shorter, actinic flux is reduced, and temperatures are colder. By analyzing the marine outflow from the NYC-DC corridor, we learn that wintertime NOx has a long lifetime, is much longer-lived during the day than at night, and its lifetime is controlled during both periods by NOx conversion to nitric acid (HNO3) as the primary NOx sink. We also employ a two-box model to constrain the wintertime plume dilution rate and HNO3 deposition rate. Additionally, analysis of the nighttime Ox budget suggests that approximately 10% of O3 is lost overnight through N2O5 dark reactions that produce HNO3.
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NASA Astrophysics Data System (ADS)
Park, Sangki; Oh, Jungmo
2018-05-01
The current commonly used nitrogen oxides (NOx) emission reduction techniques employ hydrocarbons (HCs), urea solutions, and exhaust gas emissions as the reductants. Two of the primary denitrification NOx (DeNOx) catalyst systems are the HC-lean NOx trap (HC-LNT) catalyst and urea-selective catalytic reduction (urea-SCR) catalyst. The secondary injection method depends on the type of injector, injection pressure, atomization, and spraying technique. In addition, the catalyst reaction efficiency is directly affected by the distribution of injectors; hence, the uniformity index (UI) of the reductant is very important and is the basis for system optimization. The UI of the reductant is an indicator of the NOx conversion efficiency (NCE), and good UI values can reduce the need for a catalyst. Therefore, improving the UI can reduce the cost of producing a catalytic converter, which are expensive due to the high prices of the precious metals contained therein. Accordingly, measurement of the UI is an important process in the development of catalytic systems. Two of the commonly used methods for measuring the reductant UI are (i) measuring the exhaust emissions at many points located upstream/downstream of the catalytic converter and (ii) acquisition of a reductant distribution image on a section of the exhaust pipe upstream of the catalytic converter. The purpose of this study is to develop a system and measurement algorithms to measure the exothermic response distribution in the exhaust gas as the reductant passes through the catalytic converter of the SCR catalyst system using a set of thermocouples downstream of the SCR catalyst. The system is used to measure the reductant UI, which is applied in real-time to the actual SCR system, and the results are compared for various types of mixtures for various engine operating conditions and mixer types in terms of NCE.
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40 CFR 96.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 96.188 Section 96.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.188 CAIR NOX allowance allocations to CAIR NOX opt...
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40 CFR 97.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 97.188 Section 97.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CAIR NOX Opt-In Units § 97.188 CAIR NOX allowance allocations to CAIR NOX opt-in units. (a) Timing...
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40 CFR 96.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 96.188 Section 96.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.188 CAIR NOX allowance allocations to CAIR NOX opt...
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40 CFR 96.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 96.188 Section 96.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.188 CAIR NOX allowance allocations to CAIR NOX opt...
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40 CFR 97.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 97.188 Section 97.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CAIR NOX Opt-In Units § 97.188 CAIR NOX allowance allocations to CAIR NOX opt-in units. (a) Timing...
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40 CFR 97.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 97.188 Section 97.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CAIR NOX Opt-In Units § 97.188 CAIR NOX allowance allocations to CAIR NOX opt-in units. (a) Timing...
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40 CFR 97.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 97.188 Section 97.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CAIR NOX Opt-In Units § 97.188 CAIR NOX allowance allocations to CAIR NOX opt-in units. (a) Timing...
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40 CFR 96.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 96.188 Section 96.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.188 CAIR NOX allowance allocations to CAIR NOX opt...
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40 CFR 96.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 96.188 Section 96.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.188 CAIR NOX allowance allocations to CAIR NOX opt...
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40 CFR 97.188 - CAIR NOX allowance allocations to CAIR NOX opt-in units.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX allowance allocations to CAIR NOX opt-in units. 97.188 Section 97.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CAIR NOX Opt-In Units § 97.188 CAIR NOX allowance allocations to CAIR NOX opt-in units. (a) Timing...
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The Effect of the Thickness of the Sensitive Layer on the Performance of the Accumulating NOx Sensor
Groß, Andrea; Richter, Miriam; Kubinski, David J.; Visser, Jacobus H.; Moos, Ralf
2012-01-01
A novel and promising method to measure low levels of NOx utilizes the accumulating sensor principle. During an integration cycle, incoming NOx molecules are stored in a sensitive layer based on an automotive lean NOx trap (LNT) material that changes its electrical resistivity proportional to the amount of stored NOx, making the sensor suitable for long-term detection of low levels of NOx. In this study, the influence of the thickness of the sensitive layer, prepared by multiple screen-printing, is investigated. All samples show good accumulating sensing properties for both NO and NO2. In accordance to a simplified model, the base resistance of the sensitive layer and the sensitivity to NOx decrease with increasing thickness. Contrarily, the sensor response time increases. The linear measurement range of all samples ends at a sensor response of about 30% resulting in an increase of the linearly detectable amount with the thickness. Hence, the variation of the thickness of the sensitive layer is a powerful tool to adapt the linear measurement range (proportional to the thickness) as well as the sensitivity (proportional to the inverse thickness) to the application requirements. Calculations combining the sensor model with the measurement results indicate that for operation in the linear range, about 3% of the LNT material is converted to nitrate.
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NASA Astrophysics Data System (ADS)
Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi
2016-06-01
Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd-Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.
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Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Allowance Tracking System... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS NOX Allowance Tracking System § 96.52 NOX Allowance Tracking System responsibilities of NOX authorized account representative. (a) Following the...
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Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Allowance Tracking System... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS NOX Allowance Tracking System § 96.52 NOX Allowance Tracking System responsibilities of NOX authorized account representative. (a) Following the...
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Experimental Assessment of NOx Emissions from 73 Euro 6 Diesel Passenger Cars.
Yang, Liuhanzi; Franco, Vicente; Mock, Peter; Kolke, Reinhard; Zhang, Shaojun; Wu, Ye; German, John
2015-12-15
Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selective catalytic reduction (SCR). Seventy-three Euro 6 diesel passenger cars (8 EGR only, 40 LNT, and 25 SCR) were tested on a chassis dynamometer over both the European type-approval cycle (NEDC, cold engine start) and the more realistic Worldwide harmonized light-duty test cycle (WLTC version 2.0, hot start) between 2012 and 2015. Most vehicles met the legislative limit of 0.08 g/km of NOx over NEDC (average emission factors by technology: EGR-only 0.07 g/km, LNT 0.04 g/km, and SCR 0.05 g/km), but the average emission factors rose dramatically over WLTC (EGR-only 0.17 g/km, LNT 0.21 g/km, and SCR 0.13 g/km). Five LNT-equipped vehicles exhibited very poor performance over the WLTC, emitting 7-15 times the regulated limit. These results illustrate how diesel NOx emissions are not properly controlled under the current, NEDC-based homologation framework. The upcoming real-driving emissions (RDE) regulation, which mandates an additional on-road emissions test for EU type approvals, could be a step in the right direction to address this problem.
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Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel
Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P
2012-11-20
A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.
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Vortex combustor for low NOx emissions when burning lean premixed high hydrogen content fuel
Steele, Robert C [Woodinville, WA; Edmonds, Ryan G [Renton, WA; Williams, Joseph T [Kirkland, WA; Baldwin, Stephen P [Winchester, MA
2009-10-20
A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.
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Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Allowance Tracking System... NOX AND SO2 TRADING PROGRAMS NOX Allowance Tracking System § 97.52 NOX Allowance Tracking System... Tracking System account, all submissions to the Administrator pertaining to the account, including, but not...
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Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Allowance Tracking System... NOX AND SO2 TRADING PROGRAMS NOX Allowance Tracking System § 97.52 NOX Allowance Tracking System... Tracking System account, all submissions to the Administrator pertaining to the account, including, but not...
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Wickham, David [Boulder, CO; Cook, Ronald [Lakewood, CO
2008-10-28
The present invention provides metal-exchanged hexaaluminate catalysts that exhibit good catalytic activity and/or stability at high temperatures for extended periods with retention of activity as combustion catalysts, and more generally as oxidation catalysts, that make them eminently suitable for use in methane combustion, particularly for use in natural gas fired gas turbines. The hexaaluminate catalysts of this invention are of particular interest for methane combustion processes for minimization of the generation of undesired levels (less than about 10 ppm) of NOx species. Metal exchanged hexaaluminate oxidation catalysts are also useful for oxidation of volatile organic compounds (VOC), particularly hydrocarbons. Metal exchanged hexaaluminate oxidation catalysts are further useful for partial oxidation, particularly at high temperatures, of reduced species, particularly hydrocarbons (alkanes and alkenes).
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Lammert, M. P.; McCormick, R. L.; Sindler, P.
2012-10-01
Oxides of nitrogen (NOx) emissions for transit buses for up to five different fuels and three standard transit duty cycles were compared to establish whether there is a real-world biodiesel NOx increase for transit bus duty cycles and engine calibrations. Six buses representing the majority of the current national transit fleet and including hybrid and selective catalyst reduction systems were tested on a heavy-duty chassis dynamometer with certification diesel, certification B20 blend, low aromatic (California Air Resources Board) diesel, low aromatic B20 blend, and B100 fuels over the Manhattan, Orange County and UDDS test cycles. Engine emissions certification level hadmore » the dominant effect on NOx; kinetic intensity was the secondary driving factor. The biodiesel effect on NOx emissions was not statistically significant for most buses and duty cycles for blends with certification diesel, except for a 2008 model year bus. CARB fuel had many more instances of a statistically significant effect of reducing NOx. SCR systems proved effective at reducing NOx to near the detection limit on all duty cycles and fuels, including B100. While offering a fuel economy benefit, a hybrid system significantly increased NOx emissions over a same year bus with a conventional drivetrain and the same engine.« less
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Competing reaction processes on a lattice as a paradigm for catalyst deactivation
NASA Astrophysics Data System (ADS)
Abad, E.; Kozak, J. J.
2015-02-01
We mobilize both a generating function approach and the theory of finite Markov processes to compute the probability of irreversible absorption of a randomly diffusing species on a lattice with competing reaction centers. We consider an N-site lattice populated by a single deep trap, and N -1 partially absorbing traps (absorption probability 0
trap) and the mean walk length of the random walker before localization (a measure of the reaction efficiency) are computed for different geometries. Both analytic expressions and numerical results are given for reactive processes on two-dimensional surfaces of Euler characteristic Ω =0 and Ω =2 . The results obtained allow a characterization of catalyst deactivation processes on planar surfaces and on catalyst pellets where only a single catalytic site remains fully active (deep trap), the other sites being only partially active as a result of surface poisoning. The central result of our study is that the predicted dependence of the reaction efficiency on system size N and on s is in qualitative accord with previously reported experimental results, notably catalysts exhibiting selective poisoning due to surface sites that have different affinities for chemisorption of the poisoning agent (e.g., acid zeolite catalysts). Deviations from the efficiency of a catalyst with identical sites are quantified, and we find that such deviations display a significant dependence on the topological details of the surface (for fixed values of N and s we find markedly different results for, say, a planar surface and for the polyhedral surface of a catalyst pellet). Our results highlight the importance of surface topology for the efficiency of catalytic conversion processes on inhomogeneous substrates, and in particular for those aimed at industrial applications. From our exact analysis we extract results for the two limiting cases -
Holmén, Britt A; Ayala, Alberto
2002-12-01
This paper addresses how current technologies effective for reducing PM emissions of heavy-duty engines may affect the physical characteristics of the particles emitted. Three in-use transit bus configurations were compared in terms of submicron particle size distributions using simultaneous SMPS measurements under two dilution conditions, a minidiluter and the legislated constant volume sampler (CVS). The compressed natural gas (CNG)-fueled and diesel particulate filter (DPF)-equipped diesel configurations are two "green" alternatives to conventional diesel engines. The CNG bus in this study did not have an oxidation catalyst whereas the diesel configurations (with and without particulate filter) employed catalysts. The DPF was a continuously regenerating trap (CRT). Particle size distributions were collected between 6 and 237 nm using 2-minute SMPS scans during idle and 55 mph steady-state cruise operation. Average particle size distributions collected during idle operation of the diesel baseline bus operating on ultralow sulfur fuel showed evidence for nanoparticle growth under CVS dilution conditions relative to the minidiluter. The CRT effectively reduced both accumulation and nuclei mode concentrations by factors of 10-100 except under CVS dilution conditions where nuclei mode concentrations were measured during 55 mph steady-state cruise that exceeded baseline diesel concentrations. The CVS data suggest some variability in trap performance. The CNG bus had accumulation mode concentrations 10-100x lower than the diesel baseline but often displayed large nuclei modes, especially under CVS dilution conditions. Partly this may be explained by the lack of an oxidation catalyst on the CNG, but differences between the minidiluter and CVS size distributions suggest that dilution ratio, temperature-related wall interactions, and differences in tunnel background between the diluters contributed to creating nanoparticle concentrations that sometimes exceeded diesel
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Electrochemical trapping of metastable Mn3+ ions for activation of MnO2 oxygen evolution catalysts.
Morgan Chan, Zamyla; Kitchaev, Daniil A; Nelson Weker, Johanna; Schnedermann, Christoph; Lim, Kipil; Ceder, Gerbrand; Tumas, William; Toney, Michael F; Nocera, Daniel G
2018-06-05
Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn 3+ We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn 3+ may be introduced into MnO 2 by an electrochemically induced comproportionation reaction with Mn 2+ and that Mn 3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn 3+ -activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies show that Mn 3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn 3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn 3+ (T d ) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the δ-MnO 2 polymorph incorporating Mn 3+ ions.
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Electrochemical Trapping of Metastable Mn3+ Ions for Activation of MnO2 Oxygen Evolution Catalysts
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tumas, William; Chan, Zamyla Morgan; Kitchaev, Daniil A.
Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn3+. We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn3+ may be introduced into MnO2 by an electrochemically induced comproportionation reaction with Mn2+ and that Mn3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn3+-activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies showmore » that Mn3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn3+(Td) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the d-MnO2 polymorph incorporating Mn3+ ions.« less
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EVALUATION OF SCR CATALYSTS FOR COMBINED CONTROL OF NOX AND MERCURY
The report documents two-task, bench- and pilot-scale research on the effect of selective catalytic reduction (SCR) catalysts on mercury speciation in Illinois and Powder River Basin (PRB) coal combustion flue gases. In task I, a bench-scale reactor was used to study the oxidatio...
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The role of Nox1 and Nox2 in GPVI-dependent platelet activation and thrombus formation☆
Walsh, T.G.; Berndt, M.C.; Carrim, N.; Cowman, J.; Kenny, D.; Metharom, P.
2014-01-01
Background Activation of the platelet-specific collagen receptor, glycoprotein (GP) VI, induces intracellular reactive oxygen species (ROS) production; however the relevance of ROS to GPVI-mediated platelet responses remains unclear. Objective The objective of this study was to explore the role of the ROS-producing NADPH oxidase (Nox)1 and 2 complexes in GPVI-dependent platelet activation and collagen-induced thrombus formation. Methods and results ROS production was measured by quantitating changes in the oxidation-sensitive dye, H2DCF-DA, following platelet activation with the GPVI-specific agonist, collagen related peptide (CRP). Using a pharmacological inhibitor specific for Nox1, 2-acetylphenothiazine (ML171), and Nox2 deficient mice, we show that Nox1 is the key Nox homolog regulating GPVI-dependent ROS production. Nox1, but not Nox2, was essential for CRP-dependent thromboxane (Tx)A2 production, which was mediated in part through p38 MAPK signaling; while neither Nox1 nor Nox2 was significantly involved in regulating CRP-induced platelet aggregation/integrin αIIbβ3 activation, platelet spreading, or dense granule and α-granule release (ATP release and P-selectin surface expression, respectively). Ex-vivo perfusion analysis of mouse whole blood revealed that both Nox1 and Nox2 were involved in collagen-mediated thrombus formation at arterial shear. Conclusion Together these results demonstrate a novel role for Nox1 in regulating GPVI-induced ROS production, which is essential for optimal p38 activation and subsequent TxA2 production, providing an explanation for reduced thrombus formation following Nox1 inhibition. PMID:24494191
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Graphene and g-C3N4 based photocatalysts for NOx removal: A review
NASA Astrophysics Data System (ADS)
Nikokavoura, Aspasia; Trapalis, Christos
2018-02-01
NOx liberated into atmosphere from automobile exhausts and fossil fuel combustion, comprise the major air pollutants. They are responsible for serious environmental problems such as acid rain, ozone accumulation, haze and photochemical smog. Besides they contribute to the deterioration of human health by causing decrease of the lung function and respiratory problems. The application of photocatalytic methods in order to mitigate the presence of NOx in the atmosphere is preferable as they are environmentally friendly, mild and low cost. Therefore, in this review, the photocatalytic activity of g-C3N4 and graphene based composites towards NOx removal was discussed. NOx oxidation to non volatile nitrates on the surface of graphene and g-C3N4 based photocatalysts has attracted much interest during the last years due to their structures with unique features such as large specific surface area, thermal and chemical stability and enhanced visible light utilization. The formation of 2D-2D intimate heterojunctions between graphene or g-C3N4 and other components ensures the enhanced charge transfer, lifetime of electron/hole pairs and thus photocatalytic activity. The increased visible light harvesting also contributes to their usefulness as effective photocatalytic materials. In the present work, the advantages of these novel photocatalysts and the differences/similarities between them were exhaustively highlighted. The role of graphene as catalyst promoter, electron reservoir, support and photosensitizer in its photocatalytic composites was emphasized. The effect of g-C3N4 doping and copolymerization with metals/semiconductors on its photocatalytic activity towards NOx oxidation was thoroughly discussed. Besides, the preparation methods, photocatalytic efficiencies, type of irradiation, utilization of appropriate cocatalysts, and reaction mechanisms during the photocatalytic NOx removal by graphene and g-C3N4 composies, were summarized. It was demonstrated that in the vast
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Gao, Zhiming; Daw, C Stuart; Wagner, Robert M
2013-01-01
We utilize the Powertrain Systems Analysis Toolkit (PSAT) combined with transient engine and aftertreatment component models implemented in Matlab/Simulink to simulate the effect of premixed charge compression ignition (PCCI) on the fuel economy and emissions of light-duty diesel-powered conventional and hybrid electric vehicles (HEVs). Our simulated engine is capable of both conventional diesel combustion (CDC) and premixed charge compression ignition (PCCI) over real transient driving cycles. Our simulated aftertreatment train consists of a diesel oxidation catalyst (DOC), lean NOx trap (LNT), and catalyzed diesel particulate filter (DPF). The results demonstrate that, in the simulated conventional vehicle, PCCI can significantly reducemore » fuel consumption and emissions by reducing the need for LNT and DPF regeneration. However, the opportunity for PCCI operation in the simulated HEV is limited because the engine typically experiences higher loads and multiple stop-start transients that are outside the allowable PCCI operating range. Thus developing ways of extending the PCCI operating range combined with improved control strategies for engine and emissions control management will be especially important for realizing the potential benefits of PCCI in HEVs.« less
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Atmospheric emission of NOx from mining explosives: A critical review
NASA Astrophysics Data System (ADS)
Oluwoye, Ibukun; Dlugogorski, Bogdan Z.; Gore, Jeff; Oskierski, Hans C.; Altarawneh, Mohammednoor
2017-10-01
High-energy materials such as emulsions, slurries and ammonium-nitrate fuel-oil (ANFO) explosives play crucial roles in mining, quarrying, tunnelling and many other infrastructure activities, because of their excellent transport and blasting properties. These explosives engender environmental concerns, due to atmospheric pollution caused by emission of dust and nitrogen oxides (NOx) from blasts, the latter characterised by the average emission factor of 5 kg (t AN explosive)-1. This first-of-its-kind review provides a concise literature account of the formation of NOx during blasting of AN-based explosives, employed in surface operations. We estimate the total NOx emission rate from AN-based explosives as 0.05 Tg (i.e., 5 × 104 t) N per annum, compared to the total global annual anthropogenic NOx emissions of 41.3 × 106 t N y-1. Although minor in the global sense, the large localised plumes from blasting exhibit high NOx concentration (500 ppm) exceeding up to 3000 times the international standards. This emission has profound consequences at mining sites and for adjacent atmospheric environment, necessitating expensive management of exclusion zones. The review describes different types of AN energetic materials for civilian applications, and summarises the essential properties and terminologies pertaining to their use. Furthermore, we recapitulate the mechanisms that lead to the formation of the reactive nitrogen species in blasting of AN-based explosives, review their implications to atmospheric air pollution, and compare the mechanisms with those experienced in other thermal and combustion operations. We also examine the mitigation approaches, including guidelines and operational-control measures. The review discusses the abatement technologies such as the formulation of new explosive mixtures, comprising secondary fuels, spin traps and other additives, in light of their effectiveness and efficiency. We conclude the review with a summary of unresolved problems
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Johnson, Derek R; Bedick, Clinton R; Clark, Nigel N; McKain, David L
2009-05-15
research with control optimization, urea distribution and possible use of oxidation catalysts is recommended to improve the NOx reduction capabilities while minimizing ammonia slip.
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The Active Sites of a Rod-Shaped Hollandite DeNOx Catalyst.
Hu, Pingping; Schuster, Manfred Erwin; Huang, Zhiwei; Xu, Fei; Jin, Shifeng; Chen, Yaxin; Hua, Weiming; Su, Dang Sheng; Tang, Xingfu
2015-06-26
The identification of catalytically active sites (CASs) in heterogeneous catalysis is of vital importance to design and develop improved catalysts, but remains a great challenge. The CASs have been identified in the low-temperature selective catalytic reduction of nitrogen oxides by ammonia (SCR) over a hollandite manganese oxide (HMO) catalyst with a rod-shaped morphology and one-dimensional tunnels. Electron microscopy and synchrotron X-ray diffraction determine the surface and crystal structures of the one-dimensional HMO rods closed by {100} side facets and {001} top facets. A combination of X-ray absorption spectra, molecular probes with potassium and nitric oxide, and catalytic tests reveals that the CASs are located on the {100} side facets of the HMO rods rather than on the top facets or in the tunnels, and hence semi-tunnel structural motifs on the {100} facets are evidenced to be the CASs of the SCR reaction. This work paves the way to further investigate the intrinsic mechanisms of SCR reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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2008-12-01
to decompose the urea into carbon dioxide and ammonia. This increased the pH and caused sol condensation. The mixture was calcined in air at 550°C...propane to carbon dioxide and water. Its high manganese content provides a higher intrinsic activity than the other catalysts and thus the lowest...lean natural gas turbines in order to reduce NOx emissions to reforming catalyst to convert diesel and kerosene to hydrogen rich gases. Unlike
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Kim, Young-Mee; Kim, Seok-Jo; Tatsunami, Ryosuke; Yamamura, Hisao; Fukai, Tohru; Ushio-Fukai, Masuko
2017-06-01
Reactive oxygen species (ROS) derived from NADPH oxidase (NOX) and mitochondria play a critical role in growth factor-induced switch from a quiescent to an angiogenic phenotype in endothelial cells (ECs). However, how highly diffusible ROS produced from different sources can coordinate to stimulate VEGF signaling and drive the angiogenic process remains unknown. Using the cytosol- and mitochondria-targeted redox-sensitive RoGFP biosensors with real-time imaging, here we show that VEGF stimulation in human ECs rapidly increases cytosolic RoGFP oxidation within 1 min, followed by mitochondrial RoGFP oxidation within 5 min, which continues at least for 60 min. Silencing of Nox4 or Nox2 or overexpression of mitochondria-targeted catalase significantly inhibits VEGF-induced tyrosine phosphorylation of VEGF receptor type 2 (VEGFR2-pY), EC migration and proliferation at the similar extent. Exogenous hydrogen peroxide (H 2 O 2 ) or overexpression of Nox4, which produces H 2 O 2 , increases mitochondrial ROS (mtROS), which is prevented by Nox2 siRNA, suggesting that Nox2 senses Nox4-derived H 2 O 2 to promote mtROS production. Mechanistically, H 2 O 2 increases S36 phosphorylation of p66Shc, a key mtROS regulator, which is inhibited by siNox2, but not by siNox4. Moreover, Nox2 or Nox4 knockdown or overexpression of S36 phosphorylation-defective mutant p66Shc(S36A) inhibits VEGF-induced mtROS, VEGFR2-pY, EC migration, and proliferation. In summary, Nox4-derived H 2 O 2 in part activates Nox2 to increase mtROS via pSer36-p66Shc, thereby enhancing VEGFR2 signaling and angiogenesis in ECs. This may represent a novel feed-forward mechanism of ROS-induced ROS release orchestrated by the Nox4/Nox2/pSer36-p66Shc/mtROS axis, which drives sustained activation of angiogenesis signaling program. Copyright © 2017 the American Physiological Society.
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Reduction of nitrogen oxides (NOx) by superalkalis
NASA Astrophysics Data System (ADS)
Srivastava, Ambrish Kumar
2018-03-01
NOx are major air pollutants, having negative impact on environment and consequently, human health. We propose here the single-electron reduction of NOx (x = 1, 2) using superalkalis. We study the interaction of NOx with FLi2, OLi3 and NLi4 superalkalis using density functional and single-point CCSD(T) calculations, which lead to stable superalkali-NOx ionic complexes with negatively charged NOx. This clearly reveals that the NOx can successfully be reduced to NOx- anion due to electron transfer from superalkalis. It has been also noticed that the size of superalkalis plays a crucial in the single-electron reduction of NOx.
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40 CFR 97.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 97.388 Section 97.388 Protection of Environment... NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.388 CAIR NOX Ozone Season...
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40 CFR 97.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 97.388 Section 97.388 Protection of Environment... NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.388 CAIR NOX Ozone Season...
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40 CFR 97.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 97.388 Section 97.388 Protection of Environment... NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.388 CAIR NOX Ozone Season...
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40 CFR 97.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 97.388 Section 97.388 Protection of Environment... NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.388 CAIR NOX Ozone Season...
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40 CFR 97.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 97.388 Section 97.388 Protection of Environment... NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Opt-in Units § 97.388 CAIR NOX Ozone Season...
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Guo, Qingbin; He, Yi; Sun, Tonghua; Wang, Yalin; Jia, Jinping
2014-07-15
A method combining Na2SO3 assisted electrochemical reduction and direct electrochemical reduction using Fe(II)(EDTA) solution was proposed to simultaneously remove NOx and SO2 from flue gas. Activated carbon was used as catalyst to accelerate the process. This new system features (a) direct conversion of NOx and SO2 to harmless N2 and SO4(2-); (b) fast regeneration of Fe(II)(EDTA); (c) minimum use of chemical reagents; and (d) recovery of the reduction by-product (Na2SO4). Fe(II)(EDTA) solution was continuously recycled and reused during entire process, and no harmful waste was generated. Approximately 99% NOx and 98% SO2 were removed under the optimal condition. The stability test showed that the system operation was reliable. Copyright © 2014 Elsevier B.V. All rights reserved.
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Somanna, Naveen K.; Valente, Anthony J.; Krenz, Maike; Fay, William P.; Delafontaine, Patrice; Chandrasekar, Bysani
2017-01-01
Both oxidative stress and inflammation contribute to chronic hypertension-induced myocardial fibrosis and adverse cardiac remodeling. Here we investigated whether angiotensin (Ang)-II-induced fibroblast proliferation and migration are NADPH oxidase (Nox) 4/ROS and IL-18 dependent. Our results show that the potent induction of mouse cardiac fibroblast (CF) proliferation and migration by Ang-II is markedly attenuated by Nox4 knockdown and the Nox inhibitor DPI. Further, Nox4 knockdown and DPI pre-treatment attenuate Ang-II-induced IL-18, IL-18Rα and collagen expression, and MMP9 activation. While neutralization of IL-18 blunted Ang-II-induced CF proliferation and migration, knockdown of MMP9 attenuated CF migration. The antioxidant NAC and the cell-permeable SOD mimetics Tempol, MnTBAP, and MnTMPyP attenuated oxidative stress and inhibit CF proliferation and migration. The Nox1/Nox4 dual inhibitor GKT137831 also blunted Ang-II-induced H2O2 production and CF proliferation and migration. Further, AT1 binds Nox4, and Ang-II enhanced their physical association. Notably, GKT137831 attnuated the AT1/Nox4 interaction. These results indicate that Ang-II induces CF proliferation and migration in part via Nox4/ROS-dependent IL-18 induction and MMP9 activation, and may involve AT1/Nox4 physical association. Thus, either (i) neutralizing IL-18, (ii) blocking AT1/Nox4 interaction or (iii) use of the Nox1/Nox4 inhibitor GKT137831 may have therapeutic potential in chronic hypertension-induced adverse cardiac remodeling. PMID:26445208
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NOx adsorber and method of regenerating same
Endicott, Dennis L [Peoria, IL; Verkiel, Maarten [Metamora, IL; Driscoll, James J [Dunlap, IL
2007-01-30
New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.
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APBF-DEC NOx Adsorber/DPF Project: Light-Duty Passenger Car Platform
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tomazic, D; Tatur, M; Thornton, M
A 1.9L turbo direct injection (TDI) diesel engine was modified to achieve the upcoming Tier 2 Bin 5 emission standard in combination with a NOx adsorber catalyst (NAC) and a diesel particulate filter (DPF). The primary objective for developing this test bed is to investigating the effects of different fuel sulfur contents on the performance of an advanced emission control system (ECS) in a light-duty application. During the development process, the engine-out emissions were minimized by applying a state-of-the-art combustion system in combination with cooled exhaust gas recirculation (EGR). The subsequent calibration effort resulted in emission levels requiring 80-90 percentmore » nitrogen-oxide (NOx) and particulate matter (PM) conversion rates by the corresponding ECS. The strategy development included ean/rich modulation for NAC regeneration, as well as, the desulfurization of the NAC and the regeneration of the DPF. Two slightly different ECS were investigated and calibrated. The initial vehicle results in an Audi A4 station wagon over the federal test procedure (FTP), US 06, and the highway fuel economy test (HFET) cycle indicate the potential of these configuration to meet the future Tier 2 emission standard.« less
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Musset, Boris; Clark, Robert A.; DeCoursey, Thomas E.; Petheo, Gabor L.; Geiszt, Miklos; Chen, Yumin; Cornell, John E.; Eddy, Carlton A.; Brzyski, Robert G.; El Jamali, Amina
2012-01-01
Physiological and pathological processes in spermatozoa involve the production of reactive oxygen species (ROS), but the identity of the ROS-producing enzyme system(s) remains a matter of speculation. We provide the first evidence that NOX5 NADPH oxidase is expressed and functions in human spermatozoa. Immunofluorescence microscopy detected NOX5 protein in both the flagella/neck region and the acrosome. Functionally, spermatozoa exposed to calcium ionophore, phorbol ester, or H2O2 exhibited superoxide anion production, which was blocked by addition of superoxide dismutase, a Ca2+ chelator, or inhibitors of either flavoprotein oxidases (diphenylene iododonium) or NOX enzymes (GKT136901). Consistent with our previous overexpression studies, we found that H2O2-induced superoxide production by primary sperm cells was mediated by the non-receptor tyrosine kinase c-Abl. Moreover, the HV1 proton channel, which was recently implicated in spermatozoa motility, was required for optimal superoxide production by spermatozoa. Immunoprecipitation experiments suggested an interaction among NOX5, c-Abl, and HV1. H2O2 treatment increased the proportion of motile sperm in a NOX5-dependent manner. Statistical analyses showed a pH-dependent correlation between superoxide production and enhanced sperm motility. Collectively, our findings show that NOX5 is a major source of ROS in human spermatozoa and indicate a role for NOX5-dependent ROS generation in human spermatozoa motility. PMID:22291013
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NASA Astrophysics Data System (ADS)
Rajath, S.; Nandakishora, Y.; Siddaraju, C.; Roy, Sukumar
2018-04-01
This paper explains the evaluation of erosion profiles in metal mesh supported SCR plate catalyst structures in which the glass fibers concentration in the catalyst material is considered as prime factor for erosion resistance and mechanical strength. The samples are prepared and tested at the specified and constant conditions like velocity as 30m/s, sand flow rate as 2g/min, average particle diameter 300 µm and all these samples were tested at different angles at impact preferably 15°,30°,45°,60°,75°,and 90° as per ASTM G76 standards. Say, if 5% glass fibers are present in catalyst material, then erosion resistance increases, but the density of glass fibers is very less because each glass fiber is approximately 20 microns in diameter and weight of individual is negligible. The composition in which 2% fiber is present has slightly higher erosion comparatively, but 3% glass fibers or more foreign inclusion like excessive binders can be eliminated that contributes much for the conversion of NOx. So 2% -3% glass fibers are preferred and optimized based on NOx conversion and erosion resistance property.
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In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst
NASA Astrophysics Data System (ADS)
Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian
2018-03-01
A series of ceria modified zirconium phosphate catalysts were synthesized for selective catalytic reduction of NO with ammonia (NH3-SCR). Over 98% NOx conversion and 98% N2 selectivity were obtained by the CeO2/ZrP catalyst with 20 wt.% CeO2 loading at 250-425 °C. The interaction between CeO2 and zirconium phosphate enhanced the redox abilities and surface acidities of the catalysts, resulting in the improvement of NH3-SCR activity. The in situ DRIFTS results indicated that the NH3-SCR reaction over the catalysts followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. The amide (sbnd NH2) groups and the NH4+ bonded to Brønsted acid sites were the important intermediates of Eley-Rideal mechanism.
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Weidenhof, B; Reiser, M; Stöwe, K; Maier, W F; Kim, M; Azurdia, J; Gulari, E; Seker, E; Barks, A; Laine, R M
2009-07-08
We describe here the use of liquid-feed flame spray pyrolysis (LF-FSP) to produce high surface area, nonporous, mixed-metal oxide nanopowders that were subsequently subjected to high-throughput screening to assess a set of materials for deNO(x) catalysis and hydrocarbon combustion. We were able to easily screen some 40 LF-FSP produced materials. LF-FSP produces nanopowders that very often consist of kinetic rather than thermodynamic phases. Such materials are difficult to access or are completely inaccessible via traditional catalyst preparation methods. Indeed, our studies identified a set of Ce(1-x)Zr(x)O(2) and Al(2)O(3)-Ce(1-x)Zr(x)O(2) nanopowders that offer surprisingly good activities for both NO(x) reduction and propane/propene oxidation both in high-throughput screening and in continuous flow catalytic studies. All of these catalysts offer activities comparable to traditional Pt/Al(2)O(3) catalysts but without Pt. Thus, although Pt-free, they are quite active for several extremely important emission control reactions, especially considering that these are only first generation materials. Indeed, efforts to dope the active catalysts with Pt actually led to lower catalytic activities. Thus the potential exists to completely change the materials used in emission control devices, especially for high-temperature reactions as these materials have already been exposed to 1500 degrees C; however, much research must be done before this potential is verified.
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NOX4 regulates autophagy during energy deprivation.
Sciarretta, Sebastiano; Volpe, Massimo; Sadoshima, Junichi
2014-04-01
NADPH oxidase is a cellular enzyme devoted to the production of reactive oxygen species (ROS). NOX4 and NOX2 are the main isoforms of NADPH oxidase in the cardiovascular system. In our recent study, we demonstrated that NOX4, but not NOX2, is a critical mediator of the cardiomyocyte adaptive response to energy stress. NOX4 activity and protein levels are increased in the endoplasmic reticulum (ER) but not in mitochondria of cardiomyocytes during the early phase of energy deprivation. NOX4-derived production of ROS in the ER is a critical event that activates autophagy through stimulation of the EIF2AK3/PERK-EIF2S1/eIF-2α-ATF4 pathway. NOX4-dependent autophagy is an important mechanism to preserve cellular energy and limit cell death in energy-deprived cardiomyocytes. Aside from elucidating a crucial physiological function of NOX4 during cellular energy stress, our study dissects a novel signaling mechanism that regulates autophagy under this condition.
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NOX4 regulates autophagy during energy deprivation
Sciarretta, Sebastiano; Volpe, Massimo; Sadoshima, Junichi
2014-01-01
NADPH oxidase is a cellular enzyme devoted to the production of reactive oxygen species (ROS). NOX4 and NOX2 are the main isoforms of NADPH oxidase in the cardiovascular system. In our recent study, we demonstrated that NOX4, but not NOX2, is a critical mediator of the cardiomyocyte adaptive response to energy stress. NOX4 activity and protein levels are increased in the endoplasmic reticulum (ER) but not in mitochondria of cardiomyocytes during the early phase of energy deprivation. NOX4-derived production of ROS in the ER is a critical event that activates autophagy through stimulation of the EIF2AK3/PERK-EIF2S1/eIF-2α-ATF4 pathway. NOX4-dependent autophagy is an important mechanism to preserve cellular energy and limit cell death in energy-deprived cardiomyocytes. Aside from elucidating a crucial physiological function of NOX4 during cellular energy stress, our study dissects a novel signaling mechanism that regulates autophagy under this condition. PMID:24492492
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Villani, Kenneth; Vermandel, Walter; Smets, Koen; Liang, Duoduo; van Tendeloo, Gustaaf; Martens, Johan A
2006-04-15
Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces.
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Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Specific provisions for monitoring NOX... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for...-diluent continuous emission monitoring system (consisting of a NOX pollutant concentration monitor, an O2...
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Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Specific provisions for monitoring NOX... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for...-diluent continuous emission monitoring system (consisting of a NOX pollutant concentration monitor, an O2...
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Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Specific provisions for monitoring NOX... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for...-diluent continuous emission monitoring system (consisting of a NOX pollutant concentration monitor, an O2...
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NO.sub.x catalyst and method of suppressing sulfate formation in an exhaust purification system
Balmer-Millar, Mari Lou [Chillicothe, IL; Park, Paul W [Peoria, IL; Panov, Alexander G [Peoria, IL
2007-06-26
The activity and durability of a zeolite lean-burn NOx catalyst can be increased by loading metal cations on the outer surface of the zeolite. However, the metal loadings can also oxidize sulfur dioxide to cause sulfate formation in the exhaust. The present invention is a method of suppressing sulfate formation in an exhaust purification system including a NO.sub.x catalyst. The NO.sub.x catalyst includes a zeolite loaded with at least one metal. The metal is selected from among an alkali metal, an alkaline earth metal, a lanthanide metal, a noble metal, and a transition metal. In order to suppress sulfate formation, at least a portion of the loaded metal is complexed with at least one of sulfate, phosphate, and carbonate.
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NO.sub.x catalyst and method of suppressing sulfate formation in an exhaust purification system
Balmer-Millar, Mari Lou; Park, Paul W.; Panov, Alexander G.
2006-08-22
The activity and durability of a zeolite lean-bum NOx catalyst can be increased by loading metal cations on the outer surface of the zeolite. However, the metal loadings can also oxidize sulfur dioxide to cause sulfate formation in the exhaust. The present invention is a method of suppressing sulfate formation in an exhaust purification system including a NO.sub.x catalyst. The NO.sub.x catalyst includes a zeolite loaded with at least one metal. The metal is selected from among an alkali metal, an alkaline earth metal, a lanthanide metal, a noble metal, and a transition metal. In order to suppress sulfate formation, at least a portion of the loaded metal is complexed with at least one of sulfate, phosphate, and carbonate.
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40 CFR 96.23 - NOX Budget permit contents.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget permit contents. 96.23... (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.23 NOX Budget permit contents. (a) Each NOX Budget permit (including any draft or proposed...
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Method And Apparatus For Regenerating Nox Adsorbers
Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten
2006-03-28
Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.
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Code of Federal Regulations, 2010 CFR
2010-07-01
... and heat input for the purpose of calculating NOX mass emissions. 75.71 Section 75.71 Protection of... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for the purpose of calculating NOX mass emissions. (a) Coal-fired units. The owner or operator of a coal...
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40 CFR 97.23 - NOX Budget permit contents.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget permit contents. 97.23... (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.23 NOX Budget permit contents. (a) Each NOX Budget permit will contain, in a format prescribed by the permitting...
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40 CFR 96.25 - NOX Budget permit revisions.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget permit revisions. 96.25... (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.25 NOX Budget permit revisions. (a) For a NOX Budget source with a title V operating permit...
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40 CFR 97.24 - NOX Budget permit revisions.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget permit revisions. 97.24... (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.24 NOX Budget permit revisions. (a) For a NOX Budget source with a title V operating permit, except as provided...
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40 CFR 97.23 - NOX Budget permit contents.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Budget permit contents. 97.23 Section 97.23 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.23 NOX Budget permit contents. (a) Each NOX Budget permit...
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Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew
2004-12-01
This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia Nationalmore » Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure by
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NASA Astrophysics Data System (ADS)
Jiang, Huanhuan; Jang, Myoseon; Yu, Zechen
2017-08-01
When hydrocarbons (HCs) are atmospherically oxidized, they form particulate oxidizers, including quinones, organic hydroperoxides, and peroxyacyl nitrates (PANs). These particulate oxidizers can modify cellular materials (e.g., proteins and enzymes) and adversely modulate cell functions. In this study, the contribution of particulate oxidizers in secondary organic aerosols (SOAs) to the oxidative potential was investigated. SOAs were generated from the photooxidation of toluene, 1,3,5-trimethylbenzene, isoprene, and α-pinene under varied NOx levels. Oxidative potential was determined from the typical mass-normalized consumption rate (reaction time t = 30 min) of dithiothreitol (DTTt), a surrogate for biological reducing agents. Under high-NOx conditions, the DTTt of toluene SOA was 2-5 times higher than that of the other types of SOA. Isoprene DTTt significantly decreased with increasing NOx (up to 69 % reduction by changing the HC / NOx ratio from 30 to 5). The DTTt of 1,3,5-trimethylbenzene and α-pinene SOA was insensitive to NOx under the experimental conditions of this study. The significance of quinones to the oxidative potential of SOA was tested through the enhancement of DTT consumption in the presence of 2,4-dimethylimidazole, a co-catalyst for the redox cycling of quinones; however, no significant effect of 2,4-dimethylimidazole on modulation of DTT consumption was observed for all SOA, suggesting that a negligible amount of quinones was present in the SOA of this study. For toluene and isoprene, mass-normalized DTT consumption (DTTm) was determined over an extended period of reaction time (t = 2 h) to quantify their maximum capacity to consume DTT. The total quantities of PANs and organic hydroperoxides in toluene SOA and isoprene SOA were also measured using the Griess assay and the 4-nitrophenylboronic acid assay, respectively. Under the NOx conditions (HC / NOx ratio: 5-36 ppbC ppb-1) applied in this study, the amount of organic hydroperoxides was
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NASA Astrophysics Data System (ADS)
Chen, Wangsheng; Li, Ze; Hu, Fali; Qin, Linbo; Han, Jun; Wu, Gaoming
2018-05-01
In this study, the sintered ore used as catalysts for the selective catalytic reduction (SCR) of NOX with NH3 from the sintering flue gas was investigated. The experimental results demonstrated that the maximum denitration efficiency, about 61.64%, occurred at 300 °C, 1.0 NH3/NO ratio, and 1000 h-1 gas hourly space velocity (GHSV). In order to understand the SCR denitration mechanism, the catalyst was characterized by DRIFTS, XPS, H2-TPR, BET and ICP-MS. It was found that there were Lewis and Brønsted acid sites at the surface of the sintered ore, which lead to the appearance of amide species (sbnd NH2), NH4+ intermediates, gaseous or weakly adsorbed NO2 and nitrite species. Hence, it was concluded that the reaction of the amide species (sbnd NH2) with gaseous NO (E-R mechanism) and the reaction of absorbed NO2 with the coordinated ammonia (L-H mechanism) were attributed to NOx reduction.
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Yoshida, Keiichiro; Kuwahara, Takuya; Kuroki, Tomoyuki; Okubo, Masaaki
2012-09-15
NO(x) emitted from a stationary diesel engine generator was treated with a hybrid system comprising NO(x) reduction by nonthermal plasma (NTP) and temperature swing adsorption (TSA) driven by engine waste heat. TSA produces a low-volume gas mixture of N(2) and highly concentrated NO(x), which is effectively reduced by NTP treatment. Improved treatment performance and efficiency are achieved by re-injecting the NTP-treated gas mixture into the engine intake. The system comprises two switchable adsorption chambers; the operation of this system was simulated by using a one-chamber system. The maximum energy efficiency for NO(x) treatment is 200 g(NO(2))/kWh. The respective contributions of NTP and injection of N(2) and NO(x) to the performance were theoretically analyzed. The analysis predicts that high energy efficiency and high NO(x)-removal efficiency can be simultaneously achieved with this system but miniaturization of the adsorption chambers will be a challenge. Copyright © 2012 Elsevier B.V. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Gao, Feng; Kwak, Ja Hun; Lee, Jong H.
2013-02-14
Reducing NOx emissions and particulate matter (PM) are primary concerns for diesel vehicles required to meet current LEV II and future LEV III emission standards which require 90+% NOx conversion. Currently, urea SCR as the NOx reductant and a Catalyzed Diesel Particulate Filter (CDPF) are being used for emission control system components by Ford Motor Company for 2010 and beyond diesel vehicles. Because the use of this technology for vehicle applications is new, the relative lack of experience makes it especially challenging to satisfy durability requirements. Of particular concern is being able to realistically simulate actual field aging of themore » catalyst systems under laboratory conditions. This is necessary both as a rapid assessment tool for verifying improved performance and certifiability of new catalyst formulations, and to develop a good understanding of deactivation mechanisms that can be used to develop improved catalyst materials. In addition to NOx and PM, the hydrocarbon (HC) emission standards are expected to become much more stringent during the next few years. Meanwhile, the engine-out HC emissions are expected to increase and/or be more difficult to remove. Since HC can be removed only when the catalyst becomes warm enough for its oxidation, three-way catalyst (TWC) and diesel oxidation catalyst (DOC) formulations often contain proprietary zeolite materials to hold the HC produced during the cold start period until the catalyst reaches its operating temperature (e.g., >200°C). Unfortunately, much of trapped HC tends to be released before the catalyst reaches the operating temperature. Among materials effective for trapping HC during the catalyst warm-up period, siliceous zeolites are commonly used because of their high surface area and high stability under typical operating conditions. However, there has been little research on the physical properties of these materials related to the adsorption and release of various hydrocarbon species
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Emission reduction from diesel engine using fumigation methanol and diesel oxidation catalyst.
Zhang, Z H; Cheung, C S; Chan, T L; Yao, C D
2009-07-15
This study is aimed to investigate the combined application of fumigation methanol and a diesel oxidation catalyst for reducing emissions of an in-use diesel engine. Experiments were performed on a 4-cylinder naturally-aspirated direct-injection diesel engine operating at a constant speed of 1800 rev/min for five engine loads. The experimental results show that at low engine loads, the brake thermal efficiency decreases with increase in fumigation methanol; but at high loads, it slightly increases with increase in fumigation methanol. The fumigation method results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO(2)) emissions, but decrease in nitrogen oxides (NO(x)), smoke opacity and the particulate mass concentration. For the submicron particles, the total number of particles decreases. In all cases, there is little change in geometrical mean diameter of the particles. After catalytic conversion, the HC, CO, NO(2), particulate mass and particulate number concentrations were significantly reduced at medium to high engine loads; while the geometrical mean diameter of the particles becomes larger. Thus, the combined use of fumigation methanol and diesel oxidation catalyst leads to a reduction of HC, CO, NO(x), particulate mass and particulate number concentrations at medium to high engine loads.
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2017-01-01
Particulate matter and NOx emissions from diesel exhaust remains one of the most pressing environmental problems. We explore the use of hierarchically ordered mixed Fe–Ce–Zr oxides for the simultaneous capture and oxidation of soot and reduction of NOx by ammonia in a single step. The optimized material can effectively trap the model soot particles in its open macroporous structure and oxidize the soot below 400 °C while completely removing NO in the 285–420 °C range. Surface characterization and DFT calculations emphasize the defective nature of Fe-doped ceria. The isolated Fe ions and associated oxygen vacancies catalyze facile NO reduction to N2. A mechanism for the reduction of NO with NH3 on Fe-doped ceria is proposed involving adsorbed O2. Such adsorbed O2 species will also contribute to the oxidation of soot. PMID:28603656
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NASA Astrophysics Data System (ADS)
Matsumoto, J.
2013-12-01
Nitrogen oxides, NOx (NO, NO2), and volatile organic compounds, VOCs, are important as precursors of photochemical oxidants (tropospheric ozone, O3). To predict and control photochemical oxidants, NOx emission should be captured precisely. In addition, the ratio of NO2/NOx in the exhaust gas is also important as the initial balance between NO and NO2 in the atmosphere. Monitoring the NO2/NOx ratio in the exhaust gases is essential. Especially, the influence of the NOx emission on the real atmosphere should be explored. However, conversion reactions among NO, NO2 and O3 are typically in the time scale of minutes. The NO2/NOx ratio can change rapidly just after emission. Real-time observations of these compounds in the second time scale are essential. In view of photochemical oxidant, near emission sources of NO, ozone concentration can be easily perturbed by reaction with locally emitted NO. As an index of oxidant, the sum of O3 and NO2 (Ox = O3 + NO2) is useful. In this study, a simultaneous and real-time analyzer of atmospheric Ox and NOx has been developed utilizing the dual NO2 detectors based on laser-induced fluorescence technique (LIF), and characterization of NOx emission was explored through the observations of Ox and NOx in the suburbs of Tokyo. The dual LIF detectors consisted of one laser head, two LIF cells, and one common vacuum pump. As the Ox monitor, the excess NO was added to the sample and O3 was converted to NO2, and then the sum of O3 and NO2 in the sample was quantified at the 1st LIF cell. As the NOx monitor, the excess O3 was added to the sample and NO was converted to NO2, and then the sum of NO and NO2 in the sample was quantified at the 2nd LIF cell. Both the ';Ox' and ';NOx' channels in the dual LIF analyzer were simultaneously monitoring Ox and NOx in the sample air, respectively. The temporal resolution of observed data was 1 s. Typical conversion efficiencies of O3 and NO to NO2 were more than 0.98. The lower detection limits were 0
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40 CFR 75.70 - NOX mass emissions provisions.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 17 2012-07-01 2012-07-01 false NOX mass emissions provisions. 75.70... (CONTINUED) CONTINUOUS EMISSION MONITORING NOX Mass Emissions Provisions § 75.70 NOX mass emissions... subpart to the extent that compliance is required by an applicable State or federal NOX mass emission...
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Promotion effect of H2 on ethanol oxidation and NOx reduction with ethanol over Ag/Al2O3 catalyst.
Yu, Yunbo; Li, Yi; Zhang, Xiuli; Deng, Hua; He, Hong; Li, Yuyang
2015-01-06
The catalytic partial oxidation of ethanol and selective catalytic reduction of NOx with ethanol (ethanol-SCR) over Ag/Al2O3 were studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The intermediates were identified by PIMS and their photoionization efficiency (PIE) spectra. The results indicate that H2 promotes the partial oxidation of ethanol to acetaldehyde over Ag/Al2O3, while the simultaneously occurring processes of dehydration and dehydrogenation were inhibited. H2 addition favors the formation of ammonia during ethanol-SCR over Ag/Al2O3, the occurrence of which creates an effective pathway for NOx reduction by direct reaction with NH3. Simultaneously, the enhancement of the formation of ammonia benefits its reaction with surface enolic species, resulting in producing -NCO species again, leading to enhancement of ethanol-SCR over Ag/Al2O3 by H2. Using VUV-PIMS, the reactive vinyloxy radical was observed in the gas phase during the NOx reduction by ethanol for the first time, particularly in the presence of H2. Identification of such a reaction occurring in the gas phase may be crucial for understanding the reaction pathway of HC-SCR over Ag/Al2O3.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Manea, Adrian, E-mail: adrian.manea@icbp.ro; Tanase, Laurentia I.; Raicu, Monica
Inflammation-induced changes in the activity and expression of NADPH oxidases (Nox) play a key role in atherogenesis. The molecular mechanisms of Nox regulation are scantily elucidated. Since nuclear factor-{kappa}B (NF-{kappa}B) controls the expression of many genes associated to inflammation-related diseases, in this study we have investigated the role of NF-{kappa}B signaling in the regulation of Nox1 and Nox4 transcription in human aortic smooth muscle cells (SMCs). Cultured cells were exposed to tumor necrosis factor-{alpha} (TNF{alpha}), a potent inducer of both Nox and NF-{kappa}B, up to 24 h. Lucigenin-enhanced chemiluminescence and dichlorofluorescein assays, real-time polymerase chain reaction, and Western blot analysismore » showed that inhibition of NF-{kappa}B pathway reduced significantly the TNF{alpha}-dependent up-regulation of Nox-derived reactive oxygen species production, Nox1 and Nox4 expression. In silico analysis indicated the existence of typical NF-{kappa}B elements in the promoters of Nox1 and Nox4. Transient overexpression of p65/NF-{kappa}B significantly increased the promoter activities of both isoforms. Physical interaction of p65/NF-{kappa}B proteins with the predicted sites was demonstrated by chromatin immunoprecipitation assay. These findings demonstrate that NF-{kappa}B is an essential regulator of Nox1- and Nox4-containing NADPH oxidase in SMCs. Elucidation of the complex relationships between NF-{kappa}B and Nox enzymes may lead to a novel pharmacological strategy to reduce both inflammation and oxidative stress in atherosclerosis and its associated complications.« less
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Biological removal of NOx from flue gas.
Kumaraswamy, R; Muyzer, G; Kuenen, J G; Loosdrecht, M C M
2004-01-01
BioDeNOx is a novel integrated physico-chemical and biological process for the removal of nitrogen oxides (NOx) from flue gas. Due to the high temperature of flue gas the process is performed at a temperature between 50-55 degrees C. Flue gas containing CO2, O2, SO2 and NOx, is purged through Fe(II)EDTA2- containing liquid. The Fe(II)EDTA2- complex effectively binds the NOx; the bound NOx is converted into N2 in a complex reaction sequence. In this paper an overview of the potential microbial reactions in the BioDeNOx process is discussed. It is evident that though the process looks simple, due to the large number of parallel potential reactions and serial microbial conversions, it is much more complex. There is a need for a detailed investigation in order to properly understand and optimise the process.
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Low Temperature Catalyst for NH3 Removal
NASA Technical Reports Server (NTRS)
Monje, Oscar; Melendez, Orlando
2013-01-01
Air revitalization technologies maintain a safe atmosphere inside spacecraft by the removal of C02, ammonia (NH3), and trace contaminants. NH3 onboard the International Space Station (ISS) is produced by crew metabolism, payloads, or during an accidental release of thermal control refrigerant. Currently, the ISS relies on removing NH3 via humidity condensate and the crew wears hooded respirators during emergencies. A different approach to cabin NH3 removal is to use selective catalytic oxidation (SCO), which builds on thermal catalytic oxidation concepts that could be incorporated into the existing TCCS process equipment architecture on ISS. A low temperature platinum-based catalyst (LTP-Catalyst) developed at KSC was used for converting NH3 to H20 and N2 gas by SCO. The challenge of implementing SCO is to reduce formation of undesirable byproducts like NOx (N20 and NO). Gas mixture analysis was conducted using FTIR spectrometry in the Regenerable VOC Control System (RVCS) Testbed. The RVCS was modified by adding a 66 L semi-sealed chamber, and a custom NH3 generator. The effect of temperature on NH3 removal using the LTP-Catalyst was examined. A suitable temperature was found where NH3 removal did not produce toxic NO, (NO, N02) and N20 formation was reduced.
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40 CFR 96.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 96.388 Section 96.388 Protection of Environment... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.388 CAIR...
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40 CFR 96.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 96.388 Section 96.388 Protection of Environment... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.388 CAIR...
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40 CFR 96.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 96.388 Section 96.388 Protection of Environment... SO 2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.388 CAIR...
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40 CFR 96.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 96.388 Section 96.388 Protection of Environment... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.388 CAIR...
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40 CFR 96.388 - CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX Ozone Season allowance allocations to CAIR NOX Ozone Season opt-in units. 96.388 Section 96.388 Protection of Environment... SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.388 CAIR...
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LOW-CONCENTRATION NOX EMISSIONS MEASUREMENT
The paper gives results of a recent series of low-concentration nitrogen oxides (NOx) emission measurements, made by Midwest Research Institute (MRI) during U.S. EPA-sponsored Environmental Technology Verification (ETV) test of a NOx control system called Xonon (TM) Cool Combust...
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Weyemi, Urbain; Redon, Christophe E; Aziz, Towqir; Choudhuri, Rohini; Maeda, Daisuke; Parekh, Palak R; Bonner, Michael Y; Arbiser, Jack L; Bonner, William M
2015-03-01
Human exposure to ionizing radiation from medical procedures has increased sharply in the last three decades. Recent epidemiological studies suggest a direct relationship between exposure to ionizing radiation and health problems, including cancer incidence. Therefore, minimizing the impact of radiation exposure in patients has become a priority in the development of future clinical practices. Crucial players in radiation-induced DNA damage include reactive oxygen species (ROS), but the sources of these have remained elusive. To the best of our knowledge, we show here for the first time that two members of the ROS-generating NADPH oxidase family (NOXs), NOX4 and NOX5, are involved in radiation-induced DNA damage. Depleting these two NOXs in human primary fibroblasts resulted in reduced levels of DNA damage as measured by levels of radiation-induced foci, a marker of DNA double-strand breaks (DSBs) and the comet assay coupled with increased cell survival. NOX involvement was substantiated with fulvene-5, a NOXs-specific inhibitor. Moreover, fulvene-5 mitigated radiation-induced DNA damage in human peripheral blood mononuclear cells ex vivo. Our results provide evidence that the inactivation of NOXs protects cells from radiation-induced DNA damage and cell death. These findings suggest that NOXs inhibition may be considered as a future pharmacological target to help minimize the negative effects of radiation exposure for millions of patients each year.
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Weyemi, Urbain; Redon, Christophe E.; Aziz, Towqir; Choudhuri, Rohini; Maeda, Daisuke; Parekh, Palak R.; Bonner, Michael Y.; Arbiser, Jack L.; Bonner, William M.
2015-01-01
Human exposure to ionizing radiation from medical procedures has increased sharply in the last three decades. Recent epidemiological studies suggest a direct relationship between exposure to ionizing radiation and health problems, including cancer incidence. Therefore, minimizing the impact of radiation exposure in patients has become a priority in the development of future clinical practices. Crucial players in radiation-induced DNA damage include reactive oxygen species (ROS), but the sources of these have remained elusive. To the best of our knowledge, we show here for the first time that two members of the ROS-generating NADPH oxidase family (NOXs), NOX4 and NOX5, are involved in radiation-induced DNA damage. Depleting these two NOXs in human primary fibroblasts resulted in reduced levels of DNA damage as measured by levels of radiation-induced foci, a marker of DNA double-strand breaks (DSBs) and the comet assay coupled with increased cell survival. NOX involvement was substantiated with fulvene-5, a NOXs-specific inhibitor. Moreover, fulvene-5 mitigated radiation-induced DNA damage in human peripheral blood mononuclear cells ex vivo. Our results provide evidence that the inactivation of NOXs protects cells from radiation-induced DNA damage and cell death. These findings suggest that NOXs inhibition may be considered as a future pharmacological target to help minimize the negative effects of radiation exposure for millions of patients each year. PMID:25706776
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40 CFR 96.23 - NOX Budget permit contents.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Budget permit contents. 96.23 Section 96.23 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.23 NOX Budget permit contents. (a)...
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Low NO(x) potential of gas turbine engines
NASA Technical Reports Server (NTRS)
Tacina, Robert R.
1990-01-01
The purpose is to correlate emission levels of gas turbine engines. The predictions of NO(x) emissions are based on a review of the literature of previous low NO(x) combustor programs and analytical chemical kinetic calculations. Concepts included in the literature review consisted of lean-premixed-prevaporized (LPP), rich burn/quick quench/lean burn (RQL), and direct injection. The NO(x) emissions were found to be an exponential function of adiabatic combustion temperature over a wide range of inlet temperatures, pressures and (lean) fuel-air ratios. A simple correlation of NO(x) formation with time was not found. The LPP and direct injection (using gaseous fuels) concepts have the lowest NO(x) emissions of the three concepts. The RQL data has higher values of NO(x) than the LPP concept, probably due to the stoichiometric temperatures and NO(x) production that occur during the quench step. Improvements in the quick quench step could reduce the NO(x) emissions to the LPP levels. The low NO(x) potential of LPP is offset by the operational disadvantages of its narrow stability limits and its susceptibility to autoignition/flashback. The Rich-Burn/Quick-Quench/Lean-Burn (RQL) and the direct injection concepts have the advantage of wider stability limits comparable to conventional combustors.
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Hannemann, Stefan; Casapu, Maria; Grunwaldt, Jan Dierk; Haider, Peter; Trüssel, Philippe; Baiker, Alfons; Welter, Edmund
2007-07-01
A new spectroscopic cell suitable for the analysis of heterogeneous catalysts by fluorescence EXAFS (extended X-ray absorption fine structure), transmission EXAFS and X-ray diffraction during in situ treatments and during catalysis is described. Both gas-phase and liquid-phase reactions can be investigated combined with on-line product analysis performed either by mass spectrometry or infrared spectroscopy. The set-up allows measurements from liquid-nitrogen temperature to 973 K. The catalysts are loaded preferentially as powders, but also as self-supporting wafers. The reaction cell was tested in various case studies demonstrating its flexibility and its wide applicability from model studies at liquid-nitrogen temperature to operando studies under realistic reaction conditions. Examples include structural studies during (i) the reduction of alumina-supported noble metal particles prepared by flame-spray pyrolysis and analysis of alloying in bimetallic noble metal particles (0.1%Pt-0.1%Pd/Al(2)O(3), 0.1%Pt-0.1%Ru/Al(2)O(3), 0.1%Pt-0.1%Rh/Al(2)O(3), 0.1%Au-0.1%Pd/Al(2)O(3)), (ii) reactivation of aged 0.8%Pt-16%BaO-CeO(2) NO(x) storage-reduction catalysts including the NO(x) storage/reduction cycle, and (iii) alcohol oxidation over gold catalysts (0.6%Au-20%CuO-CeO(2)).
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Lee, Chun W; Serre, Shannon D; Zhao, Yongxin; Lee, Sung Jun; Hastings, Thomas W
2008-04-01
A bench-scale reactor consisting of a natural gas burner and an electrically heated reactor housing a selective catalytic reduction (SCR) catalyst was constructed for studying elemental mercury (Hg(o)) oxidation under SCR conditions. A low sulfur Powder River Basin (PRB) subbituminous coal combustion fly ash was injected into the entrained-flow reactor along with sulfur dioxide (SO2), nitrogen oxides (NOx), hydrogen chloride (HCl), and trace Hg(o). Concentrations of Hg(o) and total mercury (Hg) upstream and downstream of the SCR catalyst were measured using a Hg monitor. The effects of HCl concentration, SCR operating temperature, catalyst space velocity, and feed rate of PRB fly ash on Hg(o) oxidation were evaluated. It was observed that HCl provides the source of chlorine for Hg(o) oxidation under simulated PRB coal-fired SCR conditions. The decrease in Hg mass balance closure across the catalyst with decreasing HCl concentration suggests that transient Hg capture on the SCR catalyst occurred during the short test exposure periods and that the outlet speciation observed may not be representative of steady-state operation at longer exposure times. Increasing the space velocity and operating temperature of the SCR led to less Hg(o) oxidized. Introduction of PRB coal fly ash resulted in slightly decreased outlet oxidized mercury (Hg2+) as a percentage of total inlet Hg and correspondingly resulted in an incremental increase in Hg capture. The injection of ammonia (NH3) for NOx reduction by SCR was found to have a strong effect to decrease Hg oxidation. The observations suggest that Hg(o) oxidation may occur near the exit region of commercial SCR reactors. Passage of flue gas through SCR systems without NH3 injection, such as during the low-ozone season, may also impact Hg speciation and capture in the flue gas.
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Aircraft NO(x) had no Unique Fingerprint on Sonex; Lightning Dominated Fresh NO(x) Sources
NASA Technical Reports Server (NTRS)
Thompson, A.; Sparling, L.; Kondo, Y.; Anderson, B.; Gregory, G.; Sachse, G.
1999-01-01
Key questions to which SONEX was directed were the following: Can aircraft corridors be detected? Is there a unique tracer for aircraft NO(x)? Can a "background" NO(x) (or NO(y) be defined? What fraction of NO(x) measured during SONEX was from aircraft? How representative was SONEX of the North Atlantic in 1997 and how typical of other years? We attempt to answer these questions through species-species correlations, probability distribution functions (PDFs), and meteorological history. There is not a unique aircraft tracer, largely due to the high variability of air mass origins and tracer ratios, which render "average" quantities meaningless. The greatest NO and NO(y) signals were associated with lightning and convective NO sources. Well-defined background CO, NO(y) and NO(y)/ozone ratio appear in subsets of two cross-track flights with subtropical origins and five flights with predominantly mid-latitude air. Forty percent of the observations on these 7 flights showed NO(y)/ozone to be above background, evidently due to unreacted NO(x). This NO(x) is a combination of aircraft, lightning and surface pollution injected by convection. The strongly subtropical signatures in SONEX observations, confirmed by pv (potential vorticity) values along flight tracks, argues for most of the unreacted NO(x) originating from lightning. Potential vorticity statistics along SONEX flight tracks in 1992-1998, and for the North Atlantic as a whole, show the SONEX meteorological environment to be representative of the North Atlantic flight corridor in the October-November period.
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System and method for diagnosing EGR performance using NOx sensor
Mazur, Christopher John
2003-12-23
A method and system for diagnosing a condition of an EGR valve used in an engine system. The EGR valve controls the portion exhaust gases produced by such engine system and fed back to an intake of such engine system. The engine system includes a NOx sensor for measuring NOx in such exhaust. The method includes: determining a time rate of change in NOx measured by the NOx sensor; comparing the determined time rate of change in the measured NOx with a predetermined expected time rate of change in measured NOx; and determining the condition of the EGR valve as a function of such comparison. The method also includes: determining from NOx measured by the NOx sensor and engine operating conditions indications of instances when samples of such measured NOx are greater than an expected maximum NOx level for such engine condition and less than an expected minimum NOx level for such engine condition; and determining the condition of the EGR valve as a function of a statistical analysis of such indications. The method includes determining whether the NOx sensor is faulty and wherein the EGR condition determining includes determining whether the NOx sensor is faulty.
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NASA Astrophysics Data System (ADS)
Mauzerall, D. L.; Sultan, B.; Kim, N.; Bradford, D.
2003-12-01
To address the problem of elevated O3 concentrations throughout the northeastern United States in summer, a NOx cap-and-trade program was implemented that reduced NOx emissions from large point sources by nearly 50%. To determine whether this program has been successful, we examine O3, NO and temperature measurements collected in the EPA-AIRS network prior to and after the cap-and-trade program went into effect in 1999. Ambient NO concentrations as measured in the EPA-AIRS network are lower in the post-cap period in all months except July. We find that the upper half of the distribution of O3 concentrations within the region is essentially unchanged (or slightly higher) in May and June, modestly reduced in July and August (except the highest concentrations which are larger in August), and significantly lower in September (ranging from 0-20 ppb lower between the mean and highest concentrations) in the 1999-2001 post-cap period relative to the 1995-1998 pre-cap period. Except for September, the frequency with which the 80ppb 8-hour NAAQS standard for O3 is exceeded has not decreased. Temperatures during the post-cap period were slightly higher in June, July and August, and slightly lower in September - likely contributing to reduced O3 levels during September in the post-cap period. To explore the possibility that trading, or selective emissions over the course of the summer, could influence regional O3 concentrations, we conduct chemical transport modeling experiments using the CAMx regional model. Even within May-September for a single year, demands for electrical power and hence NOx emissions are greater during hot than cool periods. We demonstrate that substantially more O3 is produced from identical NOx emissions from a single power plant on high temperature than on low temperature days in July 1995. Thus a lack of temporal restrictions on when in a single summer month NOx emissions may occur can result in higher O3 levels. We also demonstrate that identical NOx
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Between 350,000 and 400,000 tons of annual NOx emissions have been eliminated as a result of Phase I of the Acid Rain NOx Program. As expected. the utilities have chosen emissions averaging as the primary compliance option. This reflects that, in general, NO x reductions have ...
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Modelling NOx emissions of single droplet combustion
NASA Astrophysics Data System (ADS)
Moesl, Klaus G.; Schwing, Joachim E.; Sattelmayer, Thomas
2012-02-01
An approach for modelling and simulation of the generation of nitrogen oxide (NOx) in the gas phase surrounding single burning droplets is presented. Assuming spherical symmetry (no gravity, no forced convection), the governing equations are derived first. Then simplifications are introduced and it is proven that they are appropriate. The influences of the initial droplet diameter, the ambient conditions, and the droplet pre-vapourisation on NOx are investigated. The fuel of choice is n-decane (C10H22) as it resembles kerosene and diesel fuel best, and the complexity of the reaction mechanism is manageable. Combinations of C10H22 mechanisms and well-established NOx kinetics are evaluated in detail and validated for their applicability in the context of this work. The conducted simulations of droplet combustion in an atmosphere of hot exhaust gas show that NOx formation (by mass of fuel) increases linearly with the droplet diameter. There is a trade-off between available oxygen and ambient temperature. Increasing the equivalence ratio of the exhaust gas leads to higher NOx emissions in the very lean regime, but to lower emissions if the equivalence ratio exceeds 0.85. Pre-vapourisation of fuel at ambient conditions becomes beneficial with respect to NOx emissions only if the degree of vapourisation is above a minimum limit. If less fuel is vapourised before ignition, the NOx emissions remain almost unaffected.
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Code of Federal Regulations, 2011 CFR
2011-07-01
... and heat input for the purpose of calculating NOX mass emissions. 75.71 Section 75.71 Protection of... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for... and for a flow monitoring system and an O2 or CO2 diluent gas monitoring system to measure heat input...
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NoxO1 Controls Proliferation of Colon Epithelial Cells.
Moll, Franziska; Walter, Maria; Rezende, Flávia; Helfinger, Valeska; Vasconez, Estefania; De Oliveira, Tiago; Greten, Florian R; Olesch, Catherine; Weigert, Andreas; Radeke, Heinfried H; Schröder, Katrin
2018-01-01
Reactive oxygen species (ROS) produced by enzymes of the NADPH oxidase family serve as second messengers for cellular signaling. Processes such as differentiation and proliferation are regulated by NADPH oxidases. In the intestine, due to the exceedingly fast and constant renewal of the epithelium both processes have to be highly controlled and balanced. Nox1 is the major NADPH oxidase expressed in the gut, and its function is regulated by cytosolic subunits such as NoxO1. We hypothesize that the NoxO1-controlled activity of Nox1 contributes to a proper epithelial homeostasis and renewal in the gut. NoxO1 is highly expressed in the colon. Knockout of NoxO1 reduces the production of superoxide in colon crypts and is not subsidized by an elevated expression of its homolog p47phox. Knockout of NoxO1 increases the proliferative capacity and prevents apoptosis of colon epithelial cells. In mouse models of dextran sulfate sodium (DSS)-induced colitis and azoxymethane/DSS induced colon cancer, NoxO1 has a protective role and may influence the population of natural killer cells. NoxO1 affects colon epithelium homeostasis and prevents inflammation.
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40 CFR 97.21 - Submission of NOX Budget permit applications.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Submission of NOX Budget permit... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.21 Submission of NOX Budget permit applications. (a) Duty to apply. The NOX authorized account...
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40 CFR 96.21 - Submission of NOX Budget permit applications.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Submission of NOX Budget permit... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.21 Submission of NOX Budget permit applications. (a) Duty to apply. The NOX...
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Wu, Gang; Liu, Wen; Berka, Vladimir; Tsai, Ah-Lim
2017-09-01
To delineate the commonalities and differences in gaseous ligand discrimination among the heme-based sensors with Heme Nitric oxide/OXygen binding protein (H-NOX) scaffold, the binding kinetic parameters for gaseous ligands NO, CO, and O 2 , including K D , k on , and k off , of Shewanella oneidensis H-NOX (So H-NOX) were characterized in detail in this study and compared to those of previously characterized H-NOXs from Clostridium botulinum (Cb H-NOX), Nostoc sp. (Ns H-NOX), Thermoanaerobacter tengcongensis (Tt H-NOX), Vibrio cholera (Vc H-NOX), and human soluble guanylyl cyclase (sGC), an H-NOX analogue. The K D (NO) and K D (CO) of each bacterial H-NOX or sGC follow the "sliding scale rule"; the affinities of the bacterial H-NOXs for NO and CO vary in a small range but stronger than those of sGC by at least two orders of magnitude. On the other hand, each bacterial H-NOX exhibits different characters in the stability of its 6c NO complex, reactivity with secondary NO, stability of oxyferrous heme and autoxidation to ferric heme. A facile access channel for gaseous ligands is also identified, implying that ligand access has only minimal effect on gaseous ligand selectivity of H-NOXs or sGC. This comparative study of the binding parameters of the bacterial H-NOXs and sGC provides a basis to guide future new structural and functional studies of each specific heme sensor with the H-NOX protein fold. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.
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Enhanced Combustion Low NOx Pulverized Coal Burner
DOE Office of Scientific and Technical Information (OSTI.GOV)
David Towle; Richard Donais; Todd Hellewell
2007-06-30
For more than two decades, Alstom Power Inc. (Alstom) has developed a range of low cost, infurnace technologies for NOx emissions control for the domestic U.S. pulverized coal fired boiler market. This includes Alstom's internally developed TFS 2000{trademark} firing system, and various enhancements to it developed in concert with the U.S. Department of Energy. As of the date of this report, more than 270 units representing approximately 80,000 MWe of domestic coal fired capacity have been retrofit with Alstom low NOx technology. Best of class emissions range from 0.18 lb/MMBtu for bituminous coal to 0.10 lb/MMBtu for subbituminous coal, withmore » typical levels at 0.24 lb/MMBtu and 0.13 lb/MMBtu, respectively. Despite these gains, NOx emissions limits in the U.S. continue to ratchet down for new and existing boiler equipment. On March 10, 2005, the Environmental Protection Agency (EPA) announced the Clean Air Interstate Rule (CAIR). CAIR requires 25 Eastern states to reduce NOx emissions from the power generation sector by 1.7 million tons in 2009 and 2.0 million tons by 2015. Low cost solutions to meet such regulations, and in particular those that can avoid the need for a costly selective catalytic reduction system (SCR), provide a strong incentive to continue to improve low NOx firing system technology to meet current and anticipated NOx control regulations. The overall objective of the work is to develop an enhanced combustion, low NOx pulverized coal burner, which, when integrated with Alstom's state-of-the-art, globally air staged low NOx firing systems will provide a means to achieve: Less than 0.15 lb/MMBtu NOx emissions when firing a high volatile Eastern or Western bituminous coal, Less than 0.10 lb/MMBtu NOx emissions when firing a subbituminous coal, NOx reduction costs at least 25% lower than the costs of an SCR, Validation of the NOx control technology developed through large (15 MWt) pilot scale demonstration, and Documentation required for
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40 CFR 96.85 - NOX Budget opt-in permit contents.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget opt-in permit contents. 96... (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.85 NOX Budget opt-in permit contents. (a) Each NOX Budget opt-in permit...
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40 CFR 97.85 - NOX Budget opt-in permit contents.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Budget opt-in permit contents. 97... (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.85 NOX Budget opt-in permit contents. (a) Each NOX Budget opt-in permit will contain all elements...
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Harel, Sharon; Mayaki, Dominique; Sanchez, Veronica; Hussain, Sabah N A
2017-05-01
Angiopoietin-1 (Ang-1) is a ligand of Tie-2 receptors that promotes survival, migration, and differentiation of endothelial cells. Several studies have linked reactive oxygen species (ROS) to Ang-1 signaling and distinct angiogenic responses, but the molecular sources of these ROS have never been clearly identified. In this study, we have identified source-specific contributions of ROS to Ang-1/Tie 2 signaling and angiogenic responses in human umbilical vein endothelial cells (HUVECs), specifically the differential contributions of mitochondrial ROS (mtROS) and ROS from two isoforms of NADPH oxidase (NOX2, NOX4). We demonstrate that: 1) Ang-1 induces significant increases in mtROS production under normal conditions but does not when cells are pre-incubated with mitochondrial antioxidants; 2) Ang-1 induces rapid Tie-2-dependent increases in cytosolic ROS production but does not when NOX2 and NOX4 are knocked down; 3) Ang-1 induces simultaneous increases in phosphorylation of AKT, ERK1/2, p38, and SAPK/JNK proteins within a few minutes of exposure, but this response is strongly and selectively attenuated when NOX2 and NOX4 are knocked down or cells are pre-treated with mitochondrial antioxidants; 4) Ang-1 exerts a strong effect on HUVEC survival in serum-deprived medium and enhances cell migration and capillary tube formation, but the survival response is inhibited by NOX2 knockdown and the migration and tube formation responses are entirely absent with NOX4 knockdown or pre-treatment with mitochondrial antioxidants. We conclude that Ang-1 triggers NOX2, NOX4, and the mitochondria to release ROS and that ROS derived from these sources play distinct roles in the regulation of the Ang-1/Tie 2 signaling pathway and pro-angiogenic responses. Copyright © 2017. Published by Elsevier Inc.
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Nitrogen stable isotope composition (δ15N) of vehicle-emitted NOx.
Walters, Wendell W; Goodwin, Stanford R; Michalski, Greg
2015-02-17
The nitrogen stable isotope ratio of NOx (δ(15)N-NOx) has been proposed as a regional indicator for NOx source partitioning; however, knowledge of δ(15)N values from various NOx emission sources is limited. This study presents a detailed analysis of δ(15)N-NOx emitted from vehicle exhaust, the largest source of anthropogenic NOx. To accomplish this, NOx was collected from 26 different vehicles, including gasoline and diesel-powered engines, using a modification of a NOx collection method used by the United States Environmental Protection Agency, and δ(15)N-NOx was analyzed. The vehicles sampled in this study emitted δ(15)N-NOx values ranging from -19.1 to 9.8‰ that negatively correlated with the emitted NOx concentrations (8.5 to 286 ppm) and vehicle run time because of kinetic isotope fractionation effects associated with the catalytic reduction of NOx. A model for determining the mass-weighted δ(15)N-NOx from vehicle exhaust was constructed on the basis of average commute times, and the model estimates an average value of -2.5 ± 1.5‰, with slight regional variations. As technology improvements in catalytic converters reduce cold-start emissions in the future, it is likely to increase current δ(15)N-NOx values emitted from vehicles.
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Agriculture is a major source of NOx pollution in California
Almaraz, Maya; Bai, Edith; Wang, Chao; Trousdell, Justin; Conley, Stephen; Faloona, Ian; Houlton, Benjamin Z.
2018-01-01
Nitrogen oxides (NOx = NO + NO2) are a primary component of air pollution—a leading cause of premature death in humans and biodiversity declines worldwide. Although regulatory policies in California have successfully limited transportation sources of NOx pollution, several of the United States’ worst–air quality districts remain in rural regions of the state. Site-based findings suggest that NOx emissions from California’s agricultural soils could contribute to air quality issues; however, a statewide estimate is hitherto lacking. We show that agricultural soils are a dominant source of NOx pollution in California, with especially high soil NOx emissions from the state’s Central Valley region. We base our conclusion on two independent approaches: (i) a bottom-up spatial model of soil NOx emissions and (ii) top-down airborne observations of atmospheric NOx concentrations over the San Joaquin Valley. These approaches point to a large, overlooked NOx source from cropland soil, which is estimated to increase the NOx budget by 20 to 51%. These estimates are consistent with previous studies of point-scale measurements of NOx emissions from the soil. Our results highlight opportunities to limit NOx emissions from agriculture by investing in management practices that will bring co-benefits to the economy, ecosystems, and human health in rural areas of California. PMID:29399630
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NOX EMISSION CONTROL OPTIONS FOR COAL-FIRED ELECTRIC UTILITY BOILERS
The paper reviews NOx control options for coal-fired electric utility boilers. (NOTE: Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, revision of the New Source Performance Standards (NSPS) for NOx emissions from utility sources, and Ozone Transpor...
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Acid treatment and formation of MnWO4 belts for NH3-SCR performance of MnWOx/TiO2 catalysts
NASA Astrophysics Data System (ADS)
Zhang, Zekai; Lu, Weizhe; Zhang, Xinying; Liu, Huayan; Lu, Hanfeng
2018-06-01
NH3-SCR is an important technology to remove NOx, and non-V based catalysts development is still a hot topic in the field. To improve N2 selectivity, acid treatment was carried out to modify the properties of a MnWOx/TiO2 catalyst. Influences of acid concentration, time and temperature on the catalyst were investigated. The TEM results showed that the acid treatment removed more MnO2 species than Mn2O3 and MnWO4 and disclosed more crystal faces of the active species. The active species even formed hollow structures by Ostwald ripening mechanism, which was then corroded by acid to form the nanobelts on the surface. The working temperature window of the MnWOx/TiO2 catalyst was thereby moved to the high temperature attitude and the N2 selectivity is clearly improved.
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NASA Astrophysics Data System (ADS)
Kadam, Vaibhav
The heavy-duty diesel (HDD) engines use the diesel oxidation catalyst (DOC), catalyzed particulate filter (CPF) and urea injection based selective catalytic reduction (SCR) systems in sequential combination, to meet the US EPA 2010 PM and NOx emission standards. The SCR along with a NH 3 slip control catalyst (AMOX) offer NOx reduction >90 % with NH3 slip <20 ppm. However, there is a strong desire to further improve the NOx reduction performance of such systems, to meet the California Optional Low NOx Standard implemented since 2015. Integrating SCR functionality into a diesel particulate filter (DPF), by coating the SCR catalyst on the DPF, offers potential to reduce the system cost and packaging weight/ volume. It also provides opportunity to increases the SCR volume without affecting the overall packaging, to achieve NO x reduction efficiencies >95 %. In this research, the NOx reduction and NH3 storage performance of a Cu-zeolite SCR and Cu-zeolite SCR catalyst on DPF (SCRFRTM) were experimentally investigated based on the engine experimental data at steady state conditions. The experimental data for the production-2013-SCR and the SCRFRTM were collected (with and without PM loading in the SCRFRTM) on a Cummins ISB 2013 engine, at varying inlet temperatures, space velocities, inlet NOx concentrations and NO2/NOx ratios, to evaluate the NOx reduction, NH3 storage and NH 3 slip characteristics of the SCR catalyst. The SCRFRTM was loaded with 2 and 4 g/L of PM prior to the NOx reduction tests to study the effect of PM loading on the NOx reduction and NH3 storage performance of the SCRFRTM. The experimental setup and test procedures for evaluation of NOx reduction performance of the SCRFRTM, with and without PM loading in the SCRFRTM are described. The 1-D SCR model developed at MTU was calibrated to the engine experimental data obtained from the seven NOx reduction tests conducted with the production-2013-SCR. The performance of the 1-D SCR model was validated by
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NASA Astrophysics Data System (ADS)
Carslaw, David C.; Rhys-Tyler, Glyn
2013-12-01
In this paper we report the first direct measurements of nitrogen dioxide (NO2) in the UK using a vehicle emission remote sensing technique. Measurements of NO, NO2 and ammonia (NH3) from almost 70,000 vehicles were made spanning vehicle model years from 1985 to 2012. These measurements were carefully matched with detailed vehicle information data to understand the emission characteristics of a wide range of vehicles in a detailed way. Overall it is found that only petrol fuelled vehicles have shown an appreciable reduction in total NOx emissions over the past 15-20 years. Emissions of NOx from diesel vehicles, including those with after-treatment systems designed to reduce emissions of NOx, have not reduced over the same period of time. It is also evident that the vehicle manufacturer has a strong influence on emissions of NO2 for Euro 4/5 diesel cars and urban buses. Smaller-engined Euro 4/5 diesel cars are also shown to emit less NO2 than larger-engined vehicles. It is shown that NOx emissions from urban buses fitted with Selective Catalytic Reduction (SCR) are comparable to those using Exhaust Gas Recirculation for Euro V vehicles, while reductions in NOx of about 30% are observed for Euro IV and EEV vehicles. However, the emissions of NO2 vary widely dependent on the bus technology used. Almost all the NOx emission from Euro IV buses with SCR is in the form of NO, whereas EEV vehicles (Enhanced Environmentally friendly Vehicle) emit about 30% of the NOx as NO2. We find similarly low amounts of NO2 from trucks (3.5-12t and >12t). Finally, we show that NH3 emissions are most important for older generation catalyst-equipped petrol vehicles and SCR-equipped buses. The NH3 emissions from petrol cars have decreased by over a factor of three from the vehicles manufactured in the late 1990s compared with those manufactured in 2012. Tables of emission factors are presented for NOx, NO2 and NH3 together with uncertainties to assist the development of new emission
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High temperature durable catalyst development
NASA Technical Reports Server (NTRS)
Snow, G. C.; Tong, H.
1981-01-01
A program has been carried out to develop a catalytic reactor capable of operation in environments representative of those anticipated for advanced automotive gas turbine engines. A reactor consisting of a graded cell honeycomb support with a combination of noble metal and metal oxide catalyst coatings was built and successfully operated for 1000 hr. At an air preheat temperature of 740 K and a propane/air ratio of 0.028 by mass, the adiabatic flame temperature was held at about 1700 K. The graded cell monolithic reaction measured 5 cm in diameter by 10.2 cm in length and was operated at a reference velocity of 14.0 m/s at 1 atm. Measured NOx levels remained below 5 ppm, while unburned hydrocarbon concentrations registered near zero and carbon monoxide levels were nominally below 20 ppm.
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40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To...
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40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To...
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40 CFR 97.20 - General NOX Budget Trading Program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General NOX Budget Trading Program... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.20 General NOX Budget Trading Program permit requirements. (a) For each NOX Budget source...
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40 CFR 97.20 - General NOX Budget Trading Program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General NOX Budget Trading Program... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.20 General NOX Budget Trading Program permit requirements. (a) For each NOX Budget source...
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40 CFR 97.20 - General NOX Budget Trading Program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General NOX Budget Trading Program... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.20 General NOX Budget Trading Program permit requirements. (a) For each NOX Budget source...
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40 CFR 97.20 - General NOX Budget Trading Program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General NOX Budget Trading Program... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.20 General NOX Budget Trading Program permit requirements. (a) For each NOX Budget source...
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40 CFR 97.20 - General NOX Budget Trading Program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General NOX Budget Trading Program... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.20 General NOX Budget Trading Program permit requirements. (a) For each NOX Budget source...
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Molecular mechanisms of hypertension: role of Nox family NADPH oxidases.
Sedeek, Mona; Hébert, Richard L; Kennedy, Chris R; Burns, Kevin D; Touyz, Rhian M
2009-03-01
Molecular mechanisms contributing to the pathoetiology of hypertension are complex, involving many interacting systems such as signaling through G protein-coupled receptors, the renin-angiotensin system, vascular inflammation and remodeling, vascular senescence and aging and developmental programming, as highlighted in the current issue of the journal. Common to these systems is NADPH oxidase-derived reactive oxygen species (ROS). This editorial highlights current concepts relating to the production of ROS in hypertension and focuses on the Nox family NADPH oxidases, major sources of free radicals in the cardiovascular and renal systems. ROS play a major role as intracellular signaling molecules to regulate normal biological cellular responses. In pathological conditions, loss of redox homeostasis contributes to vascular oxidative damage. Recent evidence indicates that specific enzymes, the Nox family of NADPH oxidases, have the sole function of generating ROS in a highly regulated fashion in physiological conditions, and that in disease states, hyperactivation of Noxes contributes to oxidative stress and consequent cardiovascular and renal injury. The Nox family comprises seven members, Nox1-Nox7. Nox1, Nox2 (gp91phox-containing NADPH oxidase), Nox4 and Nox5 have been identified in the cardiovascular-renal systems and have been implicated in the pathophysiology of cardiovascular and renal disease. Noxes, which are differentially regulated in hypertension, are major sources of cardiovascular and renal oxidative stress. This has evoked considerable interest because of the possibilities that therapies targeted against specific Nox isoforms to decrease ROS generation or to increase nitric oxide availability or both may be useful in minimizing vascular injury and renal dysfunction, and thereby prevent or regress target organ damage associated with hypertension.
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Constitutive NADPH-dependent electron transferase activity of the Nox4 dehydrogenase domain.
Nisimoto, Yukio; Jackson, Heather M; Ogawa, Hisamitsu; Kawahara, Tsukasa; Lambeth, J David
2010-03-23
NADPH oxidase 4 (Nox4) is constitutively active, while Nox2 requires the cytosolic regulatory subunits p47(phox) and p67(phox) and activated Rac with activation by phorbol 12-myristate 13-acetate (PMA). This study was undertaken to identify the domain on Nox4 that confers constitutive activity. Lysates from Nox4-expressing cells exhibited constitutive NADPH- but not NADH-dependent hydrogen peroxide production with a K(m) for NADPH of 55 +/- 10 microM. The concentration of Nox4 in cell lysates was estimated using Western blotting and allowed calculation of a turnover of approximately 200 mol of H(2)O(2) min(-1) (mol of Nox4)(-1). A chimeric protein (Nox2/4) consisting of the Nox2 transmembrane (TM) domain and the Nox4 dehydrogenase (DH) domain showed H(2)O(2) production in the absence of cytosolic regulatory subunits. In contrast, chimera Nox4/2, consisting of the Nox4 TM and Nox2 DH domains, exhibited PMA-dependent activation that required coexpression of regulatory subunits. Nox DH domains from several Nox isoforms were purified and evaluated for their electron transferase activities. Nox1 DH, Nox2 DH, and Nox5 DH domains exhibited barely detectable activities toward artificial electron acceptors, while the Nox4 DH domain exhibited significant rates of reduction of cytochrome c (160 min(-1), largely superoxide dismutase-independent), ferricyanide (470 min(-1)), and other electron acceptors (artificial dyes and cytochrome b(5)). Rates were similar to those observed for H(2)O(2) production by the Nox4 holoenzyme in cell lysates. The activity required added FAD and was seen with NADPH but not NADH. These results indicate that the Nox4 DH domain exists in an intrinsically activated state and that electron transfer from NADPH to FAD is likely to be rate-limiting in the NADPH-dependent reduction of oxygen by holo-Nox4.
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40 CFR 96.24 - Effective date of initial NOX Budget permit.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Effective date of initial NOX Budget... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.24 Effective date of initial NOX Budget permit. The initial NOX Budget permit...
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40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...
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40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...
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40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To withdraw...
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40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO 2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...
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40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To withdraw...
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40 CFR 97.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins § 97.86 Withdrawal from NOX Budget Trading Program. (a) Requesting withdrawal. To withdraw...
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40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...
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40 CFR 96.86 - Withdrawal from NOX Budget Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from NOX Budget Trading... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.86 Withdrawal from NOX Budget Trading Program. (a) Requesting...
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The NOX Family of Proteins Is Also Present in Bacteria.
Hajjar, Christine; Cherrier, Mickaël V; Dias Mirandela, Gaëtan; Petit-Hartlein, Isabelle; Stasia, Marie José; Fontecilla-Camps, Juan C; Fieschi, Franck; Dupuy, Jérôme
2017-11-07
Transmembrane NADPH oxidase (NOX) enzymes have been so far only characterized in eukaryotes. In most of these organisms, they reduce molecular oxygen to superoxide and, depending on the presence of additional domains, are called NOX or dual oxidases (DUOX). Reactive oxygen species (ROS), including superoxide, have been traditionally considered accidental toxic by-products of aerobic metabolism. However, during the last decade it has become evident that both O 2 •- and H 2 O 2 are key players in complex signaling networks and defense. A well-studied example is the production of O 2 •- during the bactericidal respiratory burst of phagocytes; this production is catalyzed by NOX2. Here, we devised and applied a novel algorithm to search for additional NOX genes in genomic databases. This procedure allowed us to discover approximately 23% new sequences from bacteria (in relation to the number of NOX-related sequences identified by the authors) that we have added to the existing eukaryotic NOX family and have used to build an expanded phylogenetic tree. We cloned and overexpressed the identified nox gene from Streptococcus pneumoniae and confirmed that it codes for an NADPH oxidase. The membrane of the S. pneumoniae NOX protein (SpNOX) shares many properties with its eukaryotic counterparts, such as affinity for NADPH and flavin adenine dinucleotide, superoxide dismutase and diphenylene iodonium inhibition, cyanide resistance, oxygen consumption, and superoxide production. Traditionally, NOX enzymes in eukaryotes are related to functions linked to multicellularity. Thus, the discovery of a large family of NOX-related enzymes in the bacterial world brings up fascinating questions regarding their role in this new biological context. IMPORTANCE NADPH oxidase (NOX) enzymes have not yet been reported in bacteria. Here, we carried out computational and experimental studies to provide the first characterization of a prokaryotic NOX. Out of 996 prokaryotic proteins showing
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40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX Ozone Season allowance... IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...
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40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX Ozone Season allowance... IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...
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40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX Ozone Season allowance... IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...
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40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX Ozone Season allowance... IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...
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40 CFR 96.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX Ozone Season allowance... IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance...
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NOx emissions in China: historical trends and future perspectives
NASA Astrophysics Data System (ADS)
Zhao, B.; Wang, S. X.; Liu, H.; Xu, J. Y.; Fu, K.; Klimont, Z.; Hao, J. M.; He, K. B.; Cofala, J.; Amann, M.
2013-10-01
Nitrogen oxides (NOx) are key pollutants for the improvement of ambient air quality. Within this study we estimated the historical NOx emissions in China for the period 1995-2010, and calculated future NOx emissions every five years until 2030 under six emission scenarios. Driven by the fast growth of energy consumption, we estimate the NOx emissions in China increased rapidly from 11.0 Mt in 1995 to 26.1 Mt in 2010. Power plants, industry and transportation were major sources of NOx emissions, accounting for 28.4%, 34.0%, and 25.4% of the total NOx emissions in 2010, respectively. Two energy scenarios, a business as usual scenario (BAU) and an alternative policy scenario (PC), were developed to project future energy consumption. In 2030, total energy consumption is projected to increase by 64% and 27% from 2010 level respectively. Three sets of end-of-pipe pollution control measures, including baseline, progressive, and stringent control case, were developed for each energy scenario, thereby constituting six emission scenarios. By 2030, the total NOx emissions are projected to increase (compared to 2010) by 36% in the baseline while policy cases result in reduction up to 61% in the most ambitious case with stringent control measures. More than a third of the reduction achieved by 2030 between least and most ambitious scenario comes from power sector, and more than half is distributed equally between industry and transportation sectors. Selective catalytic reduction dominates the NOx emission reductions in power plants, while life style changes, control measures for industrial boilers and cement production are major contributors to reductions in industry. Timely enforcement of legislation on heavy-duty vehicles would contribute significantly to NOx emission reductions. About 30% of the NOx emission reduction in 2020 and 40% of the NOx emission reduction in 2030 could be treated as the ancillary benefit of energy conservation. Sensitivity analysis was conducted to
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Verification of NOx emission inventories over North Korea.
Kim, Na Kyung; Kim, Yong Pyo; Morino, Yu; Kurokawa, Jun-ichi; Ohara, Toshimasa
2014-12-01
In this study, the top-down NOx emissions estimated from satellite observations of NO2 vertical column densities over North Korea from 1996 to 2009 were analyzed. Also, a bottom-up NOx emission inventory from REAS 1.1 from 1980 to 2005 was analyzed with several statistics. REAS 1.1 was in good agreement with the top-down approach for both trend and amount. The characteristics of NOx emissions in North Korea were quite different from other developed countries including South Korea. In North Korea, emissions from industry sector was the highest followed by transportation sector in the 1980s. However, after 1990, the NOx emissions from other sector, mainly agriculture, became the 2nd highest. Also, no emission centers such as urban areas or industrial areas were distinctively observed. Finally, the monthly NOx emissions were high during the warm season. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Costa, Neide Tomimura; Scavuzzi, Bruna Miglioranza; Iriyoda, Tatiana Mayumi Veiga; Lozovoy, Marcell Alysson Batisti; Alfieri, Daniela Frizon; de Medeiros, Fabiano Aparecido; de Sá, Marcelo Cândido; Micheletti, Pâmela Lonardoni; Sekiguchi, Bruno Alexandre; Reiche, Edna Maria Vissoci; Maes, Michael; Simão, Andréa Name Colado; Dichi, Isaias
2018-04-11
Oxidative stress plays a role in the pathophysiology of rheumatoid arthritis (RA). The aim of the present study was to verify the influence of metabolic syndrome (MetS) and disease-modifying antirheumatic drugs on nitrosative and oxidative biomarkers in patients with RA. A total of 177 patients with RA and 150 healthy volunteers participated in this study, which measured lipid hydroperoxides, advanced oxidation protein products (AOPP), nitric oxide metabolites (NOx), carbonyl protein, total radical-trapping antioxidant parameter (TRAP), uric acid (UA), and C-reactive protein (CRP). NOx and the NOx/TRAP ratio were significantly increased in RA, while no significant differences in lipid hydroperoxides, AOPP, UA, and TRAP levels were found between both groups. Treatment with leflunomide was associated with increased levels of carbonyl protein, and lowered levels in TRAP and UA, while the NOx/TRAP ratio further increased. NOx and the NOx/TRAP ratio were significantly higher in women than in men, while TRAP and UA were significantly lower in women. MetS was accompanied by increased AOPP and UA levels. RA was best predicted by increased NOx/TRAP ratio, CRP, and BMI. In conclusion, our data demonstrated that NOx and NOx/TRAP are strongly associated with RA physiopathology. Our findings suggest that inhibition of iNOS may become an interesting therapeutic approach for the treatment of RA. In addition, the presence of MetS and a decrease in levels of UA by leflunomide favor redox imbalance in RA patients. More studies are needed to evaluate the impact of antioxidant capacity reduction on RA progression.
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Mráček, David; Koci, Petr; Choi, Jae -Soon; ...
2015-09-08
Periodical regeneration of NO x storage catalyst (also known as lean NO x trap) by short rich pulses of CO, H 2 and hydrocarbons is necessary for the reduction of nitrogen oxides adsorbed on the catalyst surface. Ideally, the stored NO x is converted into N 2, but N 2O and NH 3 by-products can be formed as well, particularly at low-intermediate temperatures. The N 2 and N 2O products are formed concurrently in two peaks. The primary peaks appear immediately after the rich-phase inception, and tail off with the breakthrough of the reductant front accompanied by NH 3 product.more » In addition, the secondary N 2 and N 2O peaks then appear at the rich-to-lean transition as a result of reactions between surface-deposited reductants/intermediates (CO, HC, NH 3, — NCO) and residual stored NO x under increasingly lean conditions.« less
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40 CFR 96.50 - NOX Allowance Tracking System accounts.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Allowance Tracking System accounts. 96.50 Section 96.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... IMPLEMENTATION PLANS NOX Allowance Tracking System § 96.50 NOX Allowance Tracking System accounts. (a) Nature and...
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40 CFR 96.50 - NOX Allowance Tracking System accounts.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Allowance Tracking System accounts. 96.50 Section 96.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... IMPLEMENTATION PLANS NOX Allowance Tracking System § 96.50 NOX Allowance Tracking System accounts. (a) Nature and...
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Nadesalingam, Ajantha; Chen, Jacky H K; Farahvash, Armin; Khan, Meraj A
2018-01-01
Tonicity of saline (NaCl) is important in regulating cellular functions and homeostasis. Hypertonic saline is administered to treat many inflammatory diseases, including cystic fibrosis. Excess neutrophil extracellular trap (NET) formation, or NETosis, is associated with many pathological conditions including chronic inflammation. Despite the known therapeutic benefits of hypertonic saline, its underlying mechanisms are not clearly understood. Therefore, we aimed to elucidate the effects of hypertonic saline in modulating NETosis. For this purpose, we purified human neutrophils and induced NETosis using agonists such as diacylglycerol mimetic phorbol myristate acetate (PMA), Gram-negative bacterial cell wall component lipopolysaccharide (LPS), calcium ionophores (A23187 and ionomycin from Streptomyces conglobatus ), and bacteria ( Pseudomonas aeruginosa and Staphylococcus aureus ). We then analyzed neutrophils and NETs using Sytox green assay, immunostaining of NET components and apoptosis markers, confocal microscopy, and pH sensing reagents. This study found that hypertonic NaCl suppresses nicotinamide adenine dinucleotide phosphate oxidase (NADPH2 or NOX2)-dependent NETosis induced by agonists PMA, Escherichia coli LPS (0111:B4 and O128:B12), and P. aeruginosa . Hypertonic saline also suppresses LPS- and PMA- induced reactive oxygen species production. It was determined that supplementing H 2 O 2 reverses the suppressive effect of hypertonic saline on NOX2-dependent NETosis. Many of the aforementioned suppressive effects were observed in the presence of equimolar concentrations of choline chloride and osmolytes (d-mannitol and d-sorbitol). This suggests that the mechanism by which hypertonic saline suppresses NOX2-dependent NETosis is via neutrophil dehydration. Hypertonic NaCl does not significantly alter the intracellular pH of neutrophils. We found that hypertonic NaCl induces apoptosis while suppressing NOX2-dependent NETosis. In contrast, hypertonic
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Single-Atom Pt as Co-Catalyst for Enhanced Photocatalytic H2 Evolution.
Li, Xiaogang; Bi, Wentuan; Zhang, Lei; Tao, Shi; Chu, Wangsheng; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi
2016-03-23
Isolated single-atom platinum (Pt) embedded in the sub-nanoporosity of 2D g-C3 N4 as a new form of co-catalyst is reported. The highly stable single-atom co-catalyst maximizes the atom efficiency and alters the surface trap states of g-C3 N4 , leading to significantly enhanced photocatalytic H2 evolution activity, 8.6 times higher than that of Pt nanoparticles and up to 50 times that for bare g-C3 N4 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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An assessment of cruise NOx emissions of short-haul commercial flights
NASA Astrophysics Data System (ADS)
Turgut, Enis T.; Usanmaz, Oznur
2017-12-01
Cruise NOx emissions of aircraft are an important input parameter for studies investigating climate change due to their ability to alter the concentrations of certain trace gases, such as ozone, methane, and hydroxyl in the atmosphere, and to induce positive radiative forcing. Therefore, it is of importance to minimize estimation errors on NOx emitted from aircraft engines at high altitude. In this study, the cruise NOx emissions of a frequently-used narrow-bodied aircraft type operating domestic flights in Turkey, are quantified based on numerous actual flight, actual emissions and actual meteorological data. The overall average cruise NOx emissions index is found to be ∼10 g/kg fuel. In addition, newly-developed parameters of the aircraft cruise NOx footprint and NOx intensity are calculated to be 0.5 g/pa-NM and ∼60 g/NM, respectively. Regarding the effects of flight parameters on cruise NOx emissions, while there is a distinct increase in NOx parameters with an increase in aircraft mass, this may differ for altitude. The results reveal that the NOx emissions index tends to increase slightly by 1-2%, particularly above 28,000 ft, whereas NOx intensity decreases at a rate of 2.4-2.7% per 2000 ft of cruise altitude increase.
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Oxygen Reduction at Very Low Overpotential on Nanoporous Ag Catalysts
Zhou, Yang; Lu, Qi; Zhuang, Zhongbin; ...
2015-05-07
Here we report a monolithic nanoporous Ag (np-Ag) material, synthesized using the dealloying method, as high-performance catalysts for ORR in alkaline media. As shown in Scheme 1, when there is insufficient potential input, the O 2 molecules are more likely to rebound off from a planar electrode surface (i.e. bulk polycrystalline metal, films made from nanoparticles or nanowires) before they could be reduced. In contrast, they are more likely to be trapped inside the monolithic nanoporous structure, contacting with catalytic surface for multiple time, which greatly enhances the chance for them to be fully reduced. As a result, the np-Agmore » catalyst is able to achieve an equivalent or better ORR performance than the state-of the-art Pt/C catalyst at low overpotentials, which is most desired in electrochemical energy applications for maximizing efficiency.« less
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40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...
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40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...
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40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO 2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...
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40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...
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40 CFR 96.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Trading Program. 96.186 Section 96.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Opt-in Units § 96.186 Withdrawal from CAIR NOX Annual Trading...
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40 CFR 97.22 - Information requirements for NOX Budget permit applications.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Budget permit applications. 97.22 Section 97.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.22 Information requirements for NOX Budget permit applications. A complete NOX Budget permit...
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Redox-mediated signal transduction by cardiovascular Nox NADPH oxidases.
Brandes, Ralf P; Weissmann, Norbert; Schröder, Katrin
2014-08-01
The only known function of the Nox family of NADPH oxidases is the production of reactive oxygen species (ROS). Some Nox enzymes show high tissue-specific expression and the ROS locally produced are required for synthesis of hormones or tissue components. In the cardiovascular system, Nox enzymes are low abundant and function as redox-modulators. By reacting with thiols, nitric oxide (NO) or trace metals, Nox-derived ROS elicit a plethora of cellular responses required for physiological growth factor signaling and the induction and adaptation to pathological processes. The interactions of Nox-derived ROS with signaling elements in the cardiovascular system are highly diverse and will be detailed in this article, which is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System". Copyright © 2014 Elsevier Ltd. All rights reserved.
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40 CFR 96.20 - General NOX Budget trading program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General NOX Budget trading program... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.20 General NOX Budget trading program permit requirements. (a...
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40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...
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40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...
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40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...
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40 CFR 96.20 - General NOX Budget trading program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General NOX Budget trading program... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.20 General NOX Budget trading program permit requirements. (a...
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40 CFR 96.20 - General NOX Budget trading program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General NOX Budget trading program... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.20 General NOX Budget trading program permit requirements. (a...
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40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...
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40 CFR 96.20 - General NOX Budget trading program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General NOX Budget trading program... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO 2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.20 General NOX Budget trading program permit requirements. (a...
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40 CFR 97.186 - Withdrawal from CAIR NOX Annual Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Trading Program. 97.186 Section 97.186 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Opt-In Units § 97.186 Withdrawal from CAIR NOX Annual Trading Program. Except as provided...
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40 CFR 96.20 - General NOX Budget trading program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General NOX Budget trading program... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.20 General NOX Budget trading program permit requirements. (a...
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Suppression of new particle formation from monoterpene oxidation by NOx
NASA Astrophysics Data System (ADS)
Wildt, J.; Mentel, T. F.; Kiendler-Scharr, A.; Hoffmann, T.; Andres, S.; Ehn, M.; Kleist, E.; Müsgen, P.; Rohrer, F.; Rudich, Y.; Springer, M.; Tillmann, R.; Wahner, A.
2013-10-01
The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory set up. At high NOx conditions (BVOC/NOx < 7, NOx > 23 ppb) no new particles were formed. Instead photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. As soon as [NO] was reduced to below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF orders of magnitude slower than in analogous experiments at low NOx conditions (NOx ~ 300 ppt), although OH concentrations were higher. Varying NO2 photolysis enabled showing that NO was responsible for suppression of NPF suggesting that peroxy radicals are involved in NPF. The rates of NPF and photochemical ozone production were related by power law dependence with an exponent of approximately -2. This exponent indicated that the overall peroxy radical concentration must have been the same whenever NPF appeared. Thus permutation reactions of first generation peroxy radicals cannot be the rate limiting step in NPF from monoterpene oxidation. It was concluded that permutation reactions of higher generation peroxy radical like molecules limit the rate of new particle formation. In contrast to the strong effects on the particle numbers, the formation of particle mass was less sensitive to NOx concentrations, if at all. Only at very high NOx concentrations yields were reduced by about an order of magnitude.
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Plasma-assisted combustion technology for NOx reduction in industrial burners.
Lee, Dae Hoon; Kim, Kwan-Tae; Kang, Hee Seok; Song, Young-Hoon; Park, Jae Eon
2013-10-01
Stronger regulations on nitrogen oxide (NOx) production have recently promoted the creation of a diverse array of technologies for NOx reduction, particularly within the combustion process, where reduction is least expensive. In this paper, we discuss a new combustion technology that can reduce NOx emissions within industrial burners to single-digit parts per million levels without employing exhaust gas recirculation or other NOx reduction mechanisms. This new technology uses a simple modification of commercial burners, such that they are able to perform plasma-assisted staged combustion without altering the outer configuration of the commercial reference burner. We embedded the first-stage combustor within the head of the commercial reference burner, where it operated as a reformer that could host a partial oxidation process, producing hydrogen-rich reformate or synthesis gas product. The resulting hydrogen-rich flow then ignited and stabilized the combustion flame apart from the burner rim. Ultimately, the enhanced mixing and removal of hot spots with a widened flame area acted as the main mechanisms of NOx reduction. Because this plasma burner acted as a low NOx burner and was able to reduce NOx by more than half compared to the commercial reference burner, this methodology offers important cost-effective possibilities for NOx reduction in industrial applications.
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Nitrogen Isotope Composition of Thermally Produced NOx from Various Fossil-Fuel Combustion Sources.
Walters, Wendell W; Tharp, Bruce D; Fang, Huan; Kozak, Brian J; Michalski, Greg
2015-10-06
The nitrogen stable isotope composition of NOx (δ(15)N-NOx) may be a useful indicator for NOx source partitioning, which would help constrain NOx source contributions in nitrogen deposition studies. However, there is large uncertainty in the δ(15)N-NOx values for anthropogenic sources other than on-road vehicles and coal-fired energy generating units. To this end, this study presents a broad analysis of δ(15)N-NOx from several fossil-fuel combustion sources that includes: airplanes, gasoline-powered vehicles not equipped with a three-way catalytic converter, lawn equipment, utility vehicles, urban buses, semitrucks, residential gas furnaces, and natural-gas-fired power plants. A relatively large range of δ(15)N-NOx values was measured from -28.1‰ to 8.5‰ for individual exhaust/flue samples that generally tended to be negative due to the kinetic isotope effect associated with thermal NOx production. A negative correlation between NOx concentrations and δ(15)N-NOx for fossil-fuel combustion sources equipped with selective catalytic reducers was observed, suggesting that the catalytic reduction of NOx increases δ(15)N-NOx values relative to the NOx produced through fossil-fuel combustion processes. Combining the δ(15)N-NOx measured in this study with previous published values, a δ(15)N-NOx regional and seasonal isoscape was constructed for the contiguous U.S., which demonstrates seasonal and regional importance of various NOx sources.
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Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nigel Clark; Gregory Thompson; Richard Atkinson
Selective NOx Recirculation (SNR) involves cooling the engine exhaust gas and then adsorbing the oxides of nitrogen (NOx) from the exhaust stream, followed by the periodic desorption of NOx. By returning the desorbed, concentrated NOx into the engine intake and through the combustion chamber, a percentage of the NOx is decomposed during the combustion process. An initial study of NOx decomposition during lean-burn combustion was concluded in 2004 using a 1993 Cummins L10G 240hp natural gas engine. It was observed that the air/fuel ratio, injected NO (nitric oxide) quantity and engine operating points affected NOx decomposition rates of the engine.more » Chemical kinetic modeling results were also used to determine optimum NOx decomposition operating points and were published in the 2004 annual report. A NOx decomposition rate of 27% was measured from this engine under lean-burn conditions while the software model predicted between 35-42% NOx decomposition for similar conditions. A later technology 1998 Cummins L10G 280hp natural gas engine was procured with the assistance of Cummins Inc. to replace the previous engine used for 2005 experimental research. The new engine was equipped with an electronic fuel management system with closed-loop control that provided a more stable air/fuel ratio control and improved the repeatability of the tests. The engine was instrumented with an in-cylinder pressure measurement system and electronic controls, and was adapted to operate over a range of air/fuel ratios. The engine was connected to a newly commissioned 300hp alternating current (AC) motoring dynamometer. The second experimental campaign was performed to acquire both stoichiometric and slightly rich (0.97 lambda ratio) burn NOx decomposition rates. Effects of engine load and speed on decomposition were quantified, but Exhaust Gas Recirculation (EGR) was not varied independently. Decomposition rates of up to 92% were demonstrated. Following recommendations at the 2004
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NASA Astrophysics Data System (ADS)
Wu, Ganxue; Feng, Xi; Zhang, Hailong; Zhang, Yanhua; Wang, Jianli; Chen, Yaoqiang; Dan, Yi
2018-01-01
The promotional effect of nickel additive on the catalytic performance of the representative FeVO4/TiO2 for NH3-SCR reaction is systematically studied for the first time in the present work. The experimental results showed that NOx conversion at low temperature and N2 selectivity could be significantly improved by Ni doping and 0.4Ni-FeV-Ti exhibited the highest NOx removal efficiency. Analysis by XRD, SEM/HR-TEM, Raman, TPD, DRIFTS, TPR and XPS showed that nickel doping effectively promoted the interaction of FeVO4 nanoparticles with TiO2, consequently resulting in an enhanced acidity property, improved redox activity and giving rise to the formation of the surface oxygen vacancies and defect sites.
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40 CFR 96.83 - Applying for NOX Budget opt-in permit.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applying for NOX Budget opt-in permit... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Individual Unit Opt-ins § 96.83 Applying for NOX Budget opt-in permit. (a) Applying for...
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Vehicle NOx emission plume isotopic signatures: Spatial variability across the eastern United States
NASA Astrophysics Data System (ADS)
Miller, David J.; Wojtal, Paul K.; Clark, Sydney C.; Hastings, Meredith G.
2017-04-01
On-road vehicle nitrogen oxide (NOx) sources currently dominate the U.S. anthropogenic emission budgets, yet vehicle NOx emissions have uncertain contributions to oxidized nitrogen (N) deposition patterns. Isotopic signatures serve as a potentially valuable observational tool to trace source contributions to NOx chemistry and N deposition, yet in situ emission signatures are underconstrained. We characterize the spatiotemporal variability of vehicle NOx emission isotopic signatures (δ15N-NOx) representative of U.S. vehicle fleet-integrated emission plumes. A novel combination of on-road mobile and stationary urban measurements is performed using a field and laboratory-verified technique for actively capturing NOx in solution to quantify δ15N-NOx at hourly resolution. On-road δ15N-NOx upwind of Providence, RI, ranged from -7 to -3‰. Simultaneous urban background δ15N-NOx observations showed comparable range and variations with on-road measurements, suggesting that vehicles dominate NOx emissions in the Providence area. On-road spatial δ15N-NOx variations of -9 to -2‰ were observed under various driving conditions in six urban metropolitan areas and rural interstate highways during summer and autumn in the U.S. Northeast and Midwest. Although isotopic signatures were insensitive to on-road driving mode variations, statistically significant correlations were found between δ15N-NOx and NOx emission factor extremes associated with heavy diesel emitter contributions. Overall, these results constrain an isotopic signature of fleet-integrated roadway NOx emission plumes, which have important implications for distinguishing vehicle NOx from other sources and tracking emission contributions to NOx chemistry and N deposition.
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Characteristics of fundamental combustion and NOx emission using various rank coals.
Kim, Sung Su; Kang, Youn Suk; Lee, Hyun Dong; Kim, Jae-Kwan; Hong, Sung Chang
2011-03-01
Eight types of coals of different rank were selected and their fundamental combustion characteristics were examined along with the conversion of volatile nitrogen (N) to nitrogen oxides (NOx)/fuel N to NOx. The activation energy, onset temperature, and burnout temperature were obtained from the differential thermogravimetry curve and Arrhenius plot, which were derived through thermo-gravimetric analysis. In addition, to derive the combustion of volatile N to NOx/fuel N to NOx, the coal sample, which was pretreated at various temperatures, was burned, and the results were compared with previously derived fundamental combustion characteristics. The authors' experimental results confirmed that coal rank was highly correlated with the combustion of volatile N to NOx/fuel N to NOx.
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Alternative Splicing of NOX4 in the Failing Human Heart
Varga, Zoltán V.; Pipicz, Márton; Baán, Júlia A.; Baranyai, Tamás; Koncsos, Gábor; Leszek, Przemyslaw; Kuśmierczyk, Mariusz; Sánchez-Cabo, Fátima; García-Pavía, Pablo; Brenner, Gábor J.; Giricz, Zoltán; Csont, Tamás; Mendler, Luca; Lara-Pezzi, Enrique; Pacher, Pál; Ferdinandy, Péter
2017-01-01
Increased oxidative stress is a major contributor to the development and progression of heart failure, however, our knowledge on the role of the distinct NADPH oxidase (NOX) isoenzymes, especially on NOX4 is controversial. Therefore, we aimed to characterize NOX4 expression in human samples from healthy and failing hearts. Explanted human heart samples (left and right ventricular, and septal regions) were obtained from patients suffering from heart failure of ischemic or dilated origin. Control samples were obtained from donor hearts that were not used for transplantation. Deep RNA sequencing of the cardiac transcriptome indicated extensive alternative splicing of the NOX4 gene in heart failure as compared to samples from healthy donor hearts. Long distance PCR analysis with a universal 5′-3′ end primer pair, allowing amplification of different splice variants, confirmed the presence of the splice variants. To assess translation of the alternatively spliced transcripts we determined protein expression of NOX4 by using a specific antibody recognizing a conserved region in all variants. Western blot analysis showed up-regulation of the full-length NOX4 in ischemic cardiomyopathy samples and confirmed presence of shorter isoforms both in control and failing samples with disease-associated expression pattern. We describe here for the first time that NOX4 undergoes extensive alternative splicing in human hearts which gives rise to the expression of different enzyme isoforms. The full length NOX4 is significantly upregulated in ischemic cardiomyopathy suggesting a role for NOX4 in ROS production during heart failure. PMID:29204124
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Suppression of new particle formation from monoterpene oxidation by NOx
NASA Astrophysics Data System (ADS)
Wildt, J.; Mentel, T. F.; Kiendler-Scharr, A.; Hoffmann, T.; Andres, S.; Ehn, M.; Kleist, E.; Müsgen, P.; Rohrer, F.; Rudich, Y.; Springer, M.; Tillmann, R.; Wahner, A.
2014-03-01
The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory setup. At high NOx conditions ([BVOC] / [NOx] < 7, [NOx] > 23 ppb) new particle formation was suppressed. Instead, photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. When [NO] was reduced back to levels below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF to be slowed by orders of magnitude compared to analogous experiments at low NOx conditions ([NOx] ~300 ppt), although OH concentrations were higher. Varying NO2 photolysis enabled showing that NO was responsible for suppression of NPF. This suggests that peroxy radicals are involved in NPF. The rates of NPF and photochemical ozone production were related by power law dependence with an exponent approaching -2. This exponent indicated that the overall peroxy radical concentration must have been similar when NPF occurred. Thus, permutation reactions of first-generation peroxy radicals cannot be the rate limiting step in NPF from monoterpene oxidation. It was concluded that permutation reactions of higher generation peroxy-radical-like intermediates limit the rate of new particle formation. In contrast to the strong effects on the particle numbers, the formation of particle mass was substantially less sensitive to NOx concentrations. If at all, yields were reduced by about an order of magnitude only at very high NOx concentrations.
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40 CFR 97.83 - Applying for NOX Budget opt-in permit.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applying for NOX Budget opt-in permit... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Individual Unit Opt-ins. § 97.83 Applying for NOX Budget opt-in permit. (a) Applying for initial NO X Budget opt...
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NOX2-mediated arterial dysfunction in smokers: acute effect of dark chocolate.
Loffredo, Lorenzo; Carnevale, Roberto; Perri, Ludovica; Catasca, Elisa; Augelletti, Teresa; Cangemi, Roberto; Albanese, Fabiana; Piccheri, Cristina; Nocella, Cristina; Pignatelli, Pasquale; Violi, Francesco
2011-11-01
Cocoa seems to exert artery dilatation via oxidative stress inhibition but the mechanism is still unclear. To investigate whether in smokers, dark chocolate elicits artery dilatation via down-regulation of NOX2, the catalytic core of NADPH oxidase. Flow-mediated dilatation (FMD), oxidative stress (as assessed by urinary isoprostanes excretion), nitric oxide generation (as assessed by serum levels of nitrite/nitrate (NOx)), NOX2 activity (as assessed by blood levels of soluble NOX2 derived peptide (sNOX2-dp)) and serum epicatechin were studied in 20 smokers and 20 healthy subjects (HS) in a crossover, single-blind study. Patients were randomly allocated to 40 g dark chocolate (>85% cocoa) or 40 g of milk chocolate (≤35% cocoa). FMD, urinary isoprostanes, NOx and sNOX2-dp were assessed at baseline and 2 h after chocolate ingestion. Smokers had lower FMD and NOx and higher sNOX2-dp compared to HS. After dark chocolate intake, urinary isoprostanes and sNOX2-dp significantly decreased and FMD and NOx significantly increased in smokers but not in HS. No changes of the above variables were observed after milk chocolate intake. Multiple linear regression analysis showed that in smokers the only independent predictive variable associated with a change in FMD was a change in sNOX2-dp. Serum epicatechin increased in either group only after dark chocolate intake, reaching values higher than 0.1 μM. Platelets from smokers (n=5), but not from HS (n=5), showed lower p47(phox) translocation to platelet membrane and higher NOx when incubated with 0.1-10 μM epicatechin. Results suggest that in smokers, cocoa enhances artery dilatation by lowering of NOX2 activation.
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Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nigel N. Clark
Nitric oxide (NO) and nitrogen dioxide (NO2) generated by internal combustion (IC) engines are implicated in adverse environmental and health effects. Even though lean-burn natural gas engines have traditionally emitted lower oxides of nitrogen (NOx) emissions compared to their diesel counterparts, natural gas engines are being further challenged to reduce NOx emissions to 0.1 g/bhp-hr. The Selective NOx Recirculation (SNR) approach for NOx reduction involves cooling the engine exhaust gas and then adsorbing the NOx from the exhaust stream, followed by the periodic desorption of NOx. By sending the desorbed NOx back into the intake and through the engine, amore » percentage of the NOx can be decomposed during the combustion process. SNR technology has the support of the Department of Energy (DOE), under the Advanced Reciprocating Engine Systems (ARES) program to reduce NOx emissions to under 0.1 g/bhp-hr from stationary natural gas engines by 2010. The NO decomposition phenomenon was studied using two Cummins L10G natural gas fueled spark-ignited (SI) engines in three experimental campaigns. It was observed that the air/fuel ratio ({lambda}), injected NO quantity, added exhaust gas recirculation (EGR) percentage, and engine operating points affected NOx decomposition rates within the engine. Chemical kinetic model predictions using the software package CHEMKIN were performed to relate the experimental data with established rate and equilibrium models. The model was used to predict NO decomposition during lean-burn, stoichiometric burn, and slightly rich-burn cases with added EGR. NOx decomposition rates were estimated from the model to be from 35 to 42% for the lean-burn cases and from 50 to 70% for the rich-burn cases. The modeling results provided an insight as to how to maximize NOx decomposition rates for the experimental engine. Results from this experiment along with chemical kinetic modeling solutions prompted the investigation of rich-burn operating
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MENU OF NOX EMISSION CONTROL OPTIONS FOR COAL-FIRED ELECTRIC UTILITY BOILERS
The paper reviews NOx control options for coal-fired electric utility boilers. (NOTE: Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, revision of the New Source Performance Standards (NSPS) for NOx emissions from utility sources, and Ozone Transpor...
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Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf
2017-01-01
The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. PMID:28704929
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, D.H.; Hanson, J.; Szanyi, J.
2009-04-30
Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al{sub 2}O{sub 3} with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H{sub 2} temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H{sub 2}S desorbed during the desulfation in the H{sub 2} TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates weremore » transformed to a BaS phase and remained in the catalyst rather than being removed as H{sub 2}S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H{sub 2}S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H{sub 2}O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H{sub 2}S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt-BaO/Al{sub 2}O{sub 3} lean NO{sub x} trap catalysts is markedly dependent on the sulfation levels.« less
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Control of NOx Emissions from Stationary Combustion Sources
In general, NOx control technologies are categorized as being either primary control technologies or secondary control technologies. Primary control technologies reduce the formation of NOx in the primary combustion zone. In contrast, secondary control technologies destroy the NO...
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Updates on Soil NOx parameterization in CMAQ v5.1
NOx has been well established to impact the formation of ozone and particulate matter. Soil NO emissions comprise approximately 20% of the global NOx budget and are a leading source of NOx in rural and remote areas. NO is emitted from soil as a result of complex biogeochemical i...
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Sobolevskiy, Anatoly [Orlando, FL; Rossin, Joseph A [Columbus, OH; Knapke, Michael J [Columbus, OH
2011-08-02
A process and system (18) for reducing NO.sub.x in a gas using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream (29) with a catalyst system (38) comprising sulfated zirconia washcoat particles (41), palladium, a pre-sulfated zirconia binder (44), and a promoter (45) comprising at least one of titanium, zinc, or a mixture thereof. The presence of zinc or titanium increases the resistance of the catalyst system to a sulfur and water-containing gas stream.
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Observations of interference between portable particle counters and NOx monitors
NASA Astrophysics Data System (ADS)
Bereznicki, Sarah D.; Kamal, Ali
2013-08-01
Studies in environmental exposure science have developed a preference for smaller devices that can be easily co-located without need for gas standards, such as those instruments utilized in the Near-road Exposures and Effects from Urban Air Pollutants Study (NEXUS). One observation from NEXUS was the potential for instrument interference from alcohol-based particle counters on photometric-based nitrogen oxide (NOx) monitors. This article reports the findings from laboratory tests replicating enclosed-shelter monitoring configurations and operation cycles for a common photometric-based NOx monitor and a widely used alcohol-based particle counter. These tests monitored the NOx response while the particle counter sampling interval and ambient airflow rate were varied to (1) confirm that proximity between the instruments induced interferences, (2) identify any dependencies in NOx monitor recovery on ambient airflow, and (3) determine the time needed for the NOx monitor to recover to pre-interference levels under different atmospheric conditions. During particle counter operations, NOx concentrations responded instantaneously with a several-fold jump above the measurement baseline. When the particle counter was operated for more than 10 min, this interference period also showed a marked decline in the NOx baseline. The overall recovery time of the NOx monitor depended less on the time of particle counter operation, and more on the speed of ambient airflow. If photometric-based NOx monitors need to be operated alongside alcohol-based particle counters, mechanisms must be employed to exhaust alcohol-based vapors from enclosed monitoring environments. Given the strong evidence for interference, however, it is recommended these devices not be operated within close proximity to one another.
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Choi, Dong-Hee; Kim, Ji-Hye; Seo, Joo-Ha; Lee, Jongmin; Choi, Wahn Soo; Kim, Yoon-Seong
2014-01-01
In the present study we investigated the interplay between matrix metalloproteinase 3 (MMP3) and NADPH oxidase 1 (Nox1) in the process of dopamine (DA) neuronal death. We found that MMP3 activation causes the induction of Nox1 via mitochondrial reactive oxygen species (ROS) production and subsequently Rac1 activation, eventually leading to Nox1-derived superoxide generation in a rat DA neuronal N27 cells exposed to 6-OHDA. While a MMP3 inhibitor, NNGH, largely attenuated mitochondrial ROS and subsequent Nox1 induction, both apocynin, a putative Nox inhibitor and GKT137831, a Nox1 selective inhibitor failed to reduce 6-OHDA-induced mitochondrial ROS. However, both inhibitors for MMP3 and Nox1 similarly attenuated 6-OHDA-induced N27 cell death. RNAi-mediated selective inhibition of MMP3 or Nox1 showed that knockdown of either MMP3 or Nox1 significantly reduced 6-OHDA-induced ROS generation in N27 cells. While 6-OHDA-induced Nox1 was abolished by MMP3 knockdown, Nox1 knockdown did not alter MMP3 expression. Direct overexpression of autoactivated MMP3 (actMMP3) in N27 cells or in rat substantia nigra (SN) increased expression of Nox1. Selective knockdown of Nox1 in the SN achieved by adeno-associated virus-mediated overexpression of Nox1-specific shRNA largely attenuated the actMMP3-mediated dopaminergic neuronal loss. Furthermore, Nox1 expression was significantly attenuated in Mmp3 null mice treated with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Together we established novel molecular mechanisms underlying oxidative stress-mediated dopaminergic neuronal death in which MMP3 activation is a key upstream event that leads to mitochondrial ROS, Nox1 induction and eventual dopaminergic neuronal death. Our findings may lead to the development of novel therapeutic approach.
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Characteristics of NOx emission from Chinese coal-fired power plants equipped with new technologies
NASA Astrophysics Data System (ADS)
Ma, Zizhen; Deng, Jianguo; Li, Zhen; Li, Qing; Zhao, Ping; Wang, Liguo; Sun, Yezhu; Zheng, Hongxian; Pan, Li; Zhao, Shun; Jiang, Jingkun; Wang, Shuxiao; Duan, Lei
2016-04-01
Coal combustion in coal-fired power plants is one of the important anthropogenic NOx sources, especially in China. Many policies and methods aiming at reducing pollutants, such as increasing installed capacity and installing air pollution control devices (APCDs), especially selective catalytic reduction (SCR) units, could alter NOx emission characteristics (NOx concentration, NO2/NOx ratio, and NOx emission factor). This study reported the NOx characteristics of eight new coal-fired power-generating units with different boiler patterns, installed capacities, operating loads, and coal types. The results showed that larger units produced less NOx, and anthracite combustion generated more NOx than bitumite and lignite combustion. During formation, the NOx emission factors varied from 1.81 to 6.14 g/kg, much lower than those of older units at similar scales. This implies that NOx emissions of current and future units could be overestimated if they are based on outdated emission factors. In addition, APCDs, especially SCR, greatly decreased NOx emissions, but increased NO2/NOx ratios. Regardless, the NO2/NOx ratios were lower than 5%, in accordance with the guidelines and supporting the current method for calculating NOx emissions from coal-fired power plants that ignore NO2.
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40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false CAIR NOX Ozone Season allowance... Ozone Season Allowance Allocations § 97.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...
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40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false CAIR NOX Ozone Season allowance... Ozone Season Allowance Allocations § 97.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...
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40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false CAIR NOX Ozone Season allowance... Ozone Season Allowance Allocations § 97.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...
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40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false CAIR NOX Ozone Season allowance... Ozone Season Allowance Allocations § 97.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...
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40 CFR 97.342 - CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false CAIR NOX Ozone Season allowance... Ozone Season Allowance Allocations § 97.342 CAIR NOX Ozone Season allowance allocations. (a)(1) The baseline heat input (in mmBtu) used with respect to CAIR NOX Ozone Season allowance allocations under...
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DESIGN REPORT: LOW-NOX BURNERS FOR PACKAGE BOILERS
The report describes a low-NOx burner design, presented for residual-oil-fired industrial boilers and boilers cofiring conventional fuels and nitrated hazardous wastes. The burner offers lower NOx emission levels for these applications than conventional commercial burners. The bu...
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Nitrogen oxides/sulfur oxides (NOx/SOx) Secondary NAAQS ...
This document assesses the policy basis for setting the secondary NOx/SOx NAAQS. To provide the policy assessment information for the Administrator to make a more informed decision about the basis for retaining or revising the secondary NOx/SOx NAAQS.
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Zhang, Min; Mongue-Din, Heloise; Martin, Daniel; Catibog, Norman; Smyrnias, Ioannis; Zhang, Xiaohong; Yu, Bin; Wang, Minshu; Brandes, Ralf P; Schröder, Katrin; Shah, Ajay M
2018-03-01
NADPH oxidase-4 (Nox4) is an important reactive oxygen species (ROS) source that is upregulated in the haemodynamically overloaded heart. Our previous studies using global Nox4 knockout (Nox4KO) mice demonstrated a protective role of Nox4 during chronic abdominal aortic banding, involving a paracrine enhancement of myocardial capillary density. However, other authors who studied cardiac-specific Nox4KO mice reported detrimental effects of Nox4 in response to transverse aortic constriction (TAC). It has been speculated that these divergent results are due to cell-specific actions of Nox4 (i.e. cardiomyocyte Nox4 detrimental but endothelial Nox4 beneficial) and/or differences in the model of pressure overload (i.e. abdominal banding vs. TAC). This study aimed to (i) investigate whether the effects of Nox4 on pressure overload-induced cardiac remodelling vary according to the pressure overload model and (ii) compare the roles of cardiomyocyte vs. endothelial cell Nox4. Global Nox4KO mice subjected to TAC developed worse cardiac remodelling and contractile dysfunction than wild-type littermates, consistent with our previous results with abdominal aortic banding. Next, we generated inducible cardiomyocyte-specific Nox4 KO mice (Cardio-Nox4KO) and endothelial-specific Nox4 KO mice (Endo-Nox4KO) and studied their responses to pressure overload. Both Cardio-Nox4KO and Endo-Nox4KO developed worse pressure overload-induced cardiac remodelling and dysfunction than wild-type littermates, associated with significant decrease in protein levels of HIF1α and VEGF and impairment of myocardial capillarization. Cardiomyocyte as well as endothelial cell Nox4 contributes to protection against chronic hemodynamic overload-induced cardiac remodelling, at least in part through common effects on myocardial capillary density. © The Author 2017 Published by Oxford University Press on behalf of the European Society of Cardiology.
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Exhaust emission control and diagnostics
Mazur, Christopher John; Upadhyay, Devesh
2006-11-14
A diesel engine emission control system uses an upstream oxidation catalyst and a downstream SCR catalyst to reduce NOx in a lean exhaust gas environment. The engine and upstream oxidation catalyst are configured to provide approximately a 1:1 ratio of NO to NO2 entering the downstream catalyst. In this way, the downstream catalyst is insensitive to sulfur contamination, and also has improved overall catalyst NOx conversion efficiency. Degradation of the system is determined when the ratio provided is no longer near the desired 1:1 ratio. This condition is detected using measurements of engine operating conditions such as from a NOx sensor located downstream of the catalysts. Finally, control action to adjust an injected amount of reductant in the exhaust gas based on the actual NO to NO2 ratio upstream of the SCR catalyst and downstream of the oxidation catalyst.
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40 CFR 97.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Submission of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Transfers § 97.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR NOX Ozone Season allowance...
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40 CFR 97.522 - Submission of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Submission of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.522 Submission of TR NOX Ozone Season allowance transfers. (a) An authorized account representative seeking recordation of a TR NOX Ozone Season allowance...
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40 CFR 97.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Submission of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Transfers § 97.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR NOX Ozone Season allowance...
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40 CFR 97.522 - Submission of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Submission of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.522 Submission of TR NOX Ozone Season allowance transfers. (a) An authorized account representative seeking recordation of a TR NOX Ozone Season allowance...
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40 CFR 97.522 - Submission of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Submission of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.522 Submission of TR NOX Ozone Season allowance transfers. (a) An authorized account representative seeking recordation of a TR NOX Ozone Season allowance...
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40 CFR 97.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Submission of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Transfers § 97.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR NOX Ozone Season allowance...
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40 CFR 97.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Submission of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Transfers § 97.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR NOX Ozone Season allowance...
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40 CFR 97.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Submission of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Transfers § 97.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR NOX Ozone Season allowance...
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40 CFR 97.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.120 General CAIR NOX Annual Trading Program permit requirements. (a) For...
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40 CFR 96.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.120 General CAIR NOX Annual Trading Program permit...
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40 CFR 96.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.120 General CAIR NOX Annual Trading Program permit...
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40 CFR 97.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.120 General CAIR NOX Annual Trading Program permit requirements. (a) For...
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40 CFR 97.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.120 General CAIR NOX Annual Trading Program permit requirements. (a) For...
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40 CFR 97.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.120 General CAIR NOX Annual Trading Program permit requirements. (a) For...
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40 CFR 96.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO 2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.120 General CAIR NOX Annual Trading Program permit...
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40 CFR 96.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.120 General CAIR NOX Annual Trading Program permit...
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40 CFR 97.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS Permits § 97.120 General CAIR NOX Annual Trading Program permit requirements. (a) For...
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40 CFR 96.120 - General CAIR NOX Annual Trading Program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General CAIR NOX Annual Trading... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.120 General CAIR NOX Annual Trading Program permit...
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40 CFR 97.524 - Compliance with TR NOX Ozone Season emissions limitation.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.524 Compliance with TR NOX Ozone Season emissions limitation. (a) Availability for deduction for compliance. TR NOX Ozone Season allowances are available to be...
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40 CFR 97.524 - Compliance with TR NOX Ozone Season emissions limitation.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.524 Compliance with TR NOX Ozone Season emissions limitation. (a) Availability for deduction for compliance. TR NOX Ozone Season allowances are available to be...
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40 CFR 97.525 - Compliance with TR NOX Ozone Season assurance provisions.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.525 Compliance with TR NOX Ozone Season assurance provisions. (a) Availability for deduction. TR NOX Ozone Season allowances are available to be deducted for...
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40 CFR 97.523 - Recordation of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Recordation of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.523 Recordation of TR NOX Ozone Season allowance transfers... NOX Ozone Season allowance transfer that is correctly submitted under § 97.522, the Administrator will...
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40 CFR 97.523 - Recordation of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Recordation of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.523 Recordation of TR NOX Ozone Season allowance transfers... NOX Ozone Season allowance transfer that is correctly submitted under § 97.522, the Administrator will...
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40 CFR 97.524 - Compliance with TR NOX Ozone Season emissions limitation.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.524 Compliance with TR NOX Ozone Season emissions limitation. (a) Availability for deduction for compliance. TR NOX Ozone Season allowances are available to be...
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40 CFR 97.523 - Recordation of TR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Recordation of TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.523 Recordation of TR NOX Ozone Season allowance transfers... NOX Ozone Season allowance transfer that is correctly submitted under § 97.522, the Administrator will...
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40 CFR 97.525 - Compliance with TR NOX Ozone Season assurance provisions.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.525 Compliance with TR NOX Ozone Season assurance provisions. (a) Availability for deduction. TR NOX Ozone Season allowances are available to be deducted for...
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40 CFR 97.525 - Compliance with TR NOX Ozone Season assurance provisions.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Compliance with TR NOX Ozone Season... TR NOX Ozone Season Trading Program § 97.525 Compliance with TR NOX Ozone Season assurance provisions. (a) Availability for deduction. TR NOX Ozone Season allowances are available to be deducted for...
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APBF-DEC NOx Adsorber/DPF Project: SUV / Pick-up Truck Platform
DOE Office of Scientific and Technical Information (OSTI.GOV)
Webb, C; Weber, P; Thornton,M
2003-08-24
The objective of this project is to determine the influence of diesel fuel composition on the ability of NOX adsorber catalyst (NAC) technology, in conjunction with diesel particle filters (DPFs), to achieve stringent emissions levels with a minimal fuel economy impact. The test bed for this project was intended to be a light-duty sport utility vehicle (SUV) with a goal of achieving light-duty Tier 2-Bin 5 tail pipe emission levels (0.07 g/mi. NOX and 0.01 g/mi. PM). However, with the current US market share of light-duty diesel applications being so low, no US 2002 model year (MY) light-duty truck (LDT)more » or SUV platforms equipped with a diesel engine and having a gross vehicle weight rating (GVWR) less than 8500 lb exist. While the current level of diesel engine use is relatively small in the light-duty class, there exists considerable potential for the diesel engine to gain a much larger market share in the future as manufacturers of heavy light-duty trucks (HLDTs) attempt to offset the negative impact on cooperate average fuel economy (CAFE) that the recent rise in market share of the SUVs and LDTs has caused. The US EPA Tier 2 emission standards also contain regulation to prevent the migration of heavy light-duty trucks and SUV's to the medium duty class. This preventive measure requires that all medium duty trucks, SUV's and vans in the 8,500 to 10,000 lb GVWR range being used as passenger vehicles, meet light-duty Tier 2 standards. In meeting the Tier 2 emission standards, the HLDTs and medium-duty passenger vehicles (MDPVs) will face the greatest technological challenges. Because the MDPV is the closest weight class and application relative to the potential upcoming HLDTs and SUV's, a weight class compromise was made in this program to allow the examination of using a diesel engine with a NAC-DPF system on a 2002 production vehicle. The test bed for this project is a 2500 series Chevrolet Silverado equipped with a 6.6L Duramax diesel engine certified
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[Predicting low NOx combustion property of a coal-fired boiler].
Zhou, Hao; Mao, Jianbo; Chi, Zuohe; Jiang, Xiao; Wang, Zhenhua; Cen, Kefa
2002-03-01
More attention was paid to the low NOx combustion property of the high capacity tangential firing boiler, but the NOx emission and unburned carbon content in fly ash of coal burned boiler were complicated, they were affected by many factors, such as coal character, boiler's load, air distribution, boiler style, burner style, furnace temperature, excess air ratio, pulverized coal fineness and the uniformity of the air and coal distribution, etc. In this paper, the NOx emission property and unburned carbon content in fly ash of a 600 MW utility tangentially firing coal burned boiler was experimentally investigated, and taking advantage of the nonlinear dynamics characteristics and self-learning characteristics of artificial neural network, an artificial neural network model on low NOx combustion property of the high capacity boiler was developed and verified. The results illustrated that such a model can predicate the NOx emission concentration and unburned carbon content under various operating conditions, if combined with the optimization algorithm, the operator can find the best operation condition of the low NOx combustion.
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Jiang, Xiu-Min; Wei, Li-Hong; Huang, Xiang-Yong; Zhang, Chao-Qun
2008-03-01
The combustion experiments of HG micronized coal have been conducted by combining DTG and GC-MS. The effects on NOx emission caused by particle size, oxygen concentration and heating rate were analyzed. The results show that under combustion condition that oxygen concentration is 20%, NOx precipitations of HG coal in difference sizes are single-peaked courses. Particle size impacts NOx emission from coal combustion significantly. Micro-pulverized coal reduces NOx emission. Under heating condition with 5 degrees C/min, 10 degrees C/min and 20 degrees C/min, precipitation of NO and NO2 is increased with heating rate rising, and temperature parallelized with maximum NO precipitation rate is increased with heating rate rising as well. With increasing of oxygen concentration in combustion, NOx precipitation increases correspondingly, and temperature parallelized with maximum NOx precipitation rate is reduced.
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40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...
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40 CFR 97.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Recordation of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Tracking System § 97.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in the CAIR NOX Ozone Season sources...
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40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Withdrawal from CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...
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40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Withdrawal from CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...
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40 CFR 97.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Recordation of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Tracking System § 97.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in the CAIR NOX Ozone Season sources...
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40 CFR 97.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Recordation of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Tracking System § 97.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in the CAIR NOX Ozone Season sources...
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40 CFR 97.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Recordation of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Tracking System § 97.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in the CAIR NOX Ozone Season sources...
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40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Withdrawal from CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...
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40 CFR 96.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Withdrawal from CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Opt-in Units § 96.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season...
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40 CFR 97.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Recordation of CAIR NOX Ozone Season... CAIR NOX Ozone Season Allowance Tracking System § 97.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in the CAIR NOX Ozone Season sources...
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40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Withdrawal from CAIR NOX Ozone Season... CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season opt-in unit may withdraw...
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40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Withdrawal from CAIR NOX Ozone Season... CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season opt-in unit may withdraw...
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40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Withdrawal from CAIR NOX Ozone Season... CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season opt-in unit may withdraw...
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40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Withdrawal from CAIR NOX Ozone Season... CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season opt-in unit may withdraw...
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40 CFR 97.386 - Withdrawal from CAIR NOX Ozone Season Trading Program.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Withdrawal from CAIR NOX Ozone Season... CAIR NOX Ozone Season Opt-in Units § 97.386 Withdrawal from CAIR NOX Ozone Season Trading Program. Except as provided under paragraph (g) of this section, a CAIR NOX Ozone Season opt-in unit may withdraw...
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A new method and application for determining the nitrogen isotopic composition of NOx
NASA Astrophysics Data System (ADS)
Hastings, M. G.; Miller, D. J.; Wojtal, P.; O'Connor, M.
2015-12-01
Atmospheric nitrogen oxides (NOx = NO + NO2) play key roles in atmospheric chemistry, air quality, and radiative forcing, and contribute to nitric acid deposition. Sources of NOx include both natural and anthropogenic emissions, which vary significantly in space and time. NOx isotopic signatures offer a potentially valuable tool to trace source impacts on atmospheric chemistry and regional acid deposition. Previous work on NOx isotopic signatures suggests large ranges in values, even from the same emission source, as well as overlapping ranges amongst different sources, making it difficult to use the isotopic composition as a quantitative tracer of source influences. These prior measurements have utilized a variety of methods for collecting the NOx as nitrate or nitrite for isotopic analysis, and testing of some of these methods (including active and passive collections) reveal inconsistencies in efficiency of collection, as well as issues related to changes in conditions such as humidity, temperature, and NOx fluxes. A recently developed method allows for accurately measuring the nitrogen isotopic composition of NOx (NOx = NO + NO2) after capturing the NOx in a potassium permanganate/sodium hydroxide solution as nitrate (Fibiger et al., Anal. Chem., 2014). The method has been thoroughly tested in the laboratory and field, and efficiently collects NO and NO2 under a variety of conditions. There are several advantages to collecting NOx actively, including the ability to collect over minutes to hourly time scales, and the ability to collect in environments with highly variable NOx sources and concentrations. Challenges include a nitrate background present in potassium permanganate (solid and liquid forms), accurately deriving ambient NOx concentrations based upon flow rate and solution concentrations above this variable background, and potential interferences from other nitrogen species. This method was designed to collect NOx in environments with very different
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Petrushanko, Irina Yu; Lobachev, Vladimir M; Kononikhin, Alexey S; Makarov, Alexander A; Devred, Francois; Kovacic, Hervé; Kubatiev, Aslan A; Tsvetkov, Philipp O
2016-01-01
NOX5 protein, one of the most active generators of reactive oxygen species (ROS), plays an important role in many processes, including regulation of cell growth, death and differentiation. Because of its central role in ROS generation, it needs to be tightly regulated to guarantee cellular homeostasis. Contrary to other members of NADPH-oxidases family, NOX5 has its own regulatory calcium-binding domain and thus could be activated directly by calcium ions. While several mechanisms of activation have been described, very little is known about the mechanisms that could prevent the overproduction of ROS by NOX5. In the present study using calorimetric methods and circular dichroism we found that oxidation of cysteine and methionine residues of NOX5 decreases binding of Ca2+ ions and perturbs both secondary and tertiary structure of protein. Our data strongly suggest that oxidation of calcium-binding domain of NOX5 could be implicated in its inactivation, serving as a possible defense mechanism against oxidative stress.
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NATURAL GAS REBURNING FOR NOX CONTROL ON A CYCLONE-FIRED BOILER
The paper discusses natural gas reburning (fuel staging) for nitrogen oxide (NOx) control on a cyclone-fired boiler. eburning is an in-furnace NOx combustion modification technology that has been shown to reduce NOx by 50-60%. eburning is accomplished by injecting fuel downstream...
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40 CFR 96.22 - Information requirements for NOX Budget permit applications.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Budget permit applications. 96.22 Section 96.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.22 Information requirements for NOX Budget permit applications...
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NOx Emissions Performance and Correlation Equations for a Multipoint LDI Injector
NASA Technical Reports Server (NTRS)
He, Zhuohui J.; Chang, Clarence T.; Follen, Caitlin E.
2015-01-01
Lean Direct Injection (LDI) is a combustor concept that reduces nitrogen oxides (NOx) emissions. This paper looks at a 3-zone multipoint LDI concept developed by Parker Hannifin Corporation. The concept was tested in a flame-tube test facility at NASA Glenn Research Center. Due to test facility limitations, such as inlet air temperature and pressure, the flame-tube test was not able to cover the full set of engine operation conditions. Three NOx correlation equations were developed based on assessing NOx emissions dependencies on inlet air pressure (P3), inlet air temperature (T3), and fuel air equivalence ratio (?) to estimate the NOx emissions at the unreachable high engine power conditions. As the results, the NOx emissions are found to be a strong function of combustion inlet air temperature and fuel air equivalence ratio but a weaker function of inlet air pressure. With these three equations, the NOx emissions performance of this injector concept is calculated as a 66% reduction relative to the ICAO CAEP-6 standard using a 55:1 pressure-ratio engine cycle. Uncertainty in the NOx emissions estimation increases as the extrapolation range departs from the experimental conditions. Since maximum inlet air pressure tested was less than 50% of the full power engine inlet air pressure, a future experiment at higher inlet air pressure conditions is needed to confirm the NOx emissions dependency on inlet air pressure.
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Variation of radiative forcings and global warming potentials from regional aviation NOx emissions
NASA Astrophysics Data System (ADS)
Skowron, Agnieszka; Lee, David S.; De León, Ruben R.
2015-03-01
The response to hemispherical and regional aircraft NOx emissions is explored by using two climate metrics: radiative forcing (RF) and Global Warming Potential (GWP). The global chemistry transport model, MOZART-3 CTM, is applied in this study for a series of incremental aircraft NOx emission integrations to different regions. It was found that the sensitivity of chemical responses per unit emission rate from regional aircraft NOx emissions varies with size of aircraft NOx emission rate and that climate metric values decrease with increasing aircraft NOx emission rates, except for Southeast Asia. Previous work has recognized that aircraft NOx GWPs may vary regionally. However, the way in which these regional GWPs are calculated are critical. Previous studies have added a fixed amount of NOx to different regions. This approach can heavily bias the results of a regional GWP because of the well-established sensitivity of O3 production to background NOx whereby the Ozone Production Efficiency (OPE) is greater at small background NOx. Thus, even a small addition of NOx in a clean-air area can produce a large O3 response. Using this 'fixed addition' method of 0.035 Tg(N) yr-1, results in the greatest effect observed for North Atlantic and Brazil, ∼10.0 mW m-2/Tg(N) yr-1. An alternative 'proportional approach' is also taken that preserves the subtle balance of local NOx-O3-CH4 systems with the existing emission patterns of aircraft and background NOx, whereby a proportional amount of aircraft NOx, 5% (N) yr-1, is added to each region in order to determine the response. This results in the greatest effect observed for North Pacific that with its net NOx RF of 23.7 mW m-2/Tg(N) yr-1 is in contrast with the 'fixed addition' method. For determining regional NOx GWPs, it is argued that the 'proportional' approach gives more representative results. However, a constraint of both approaches is that the regional GWP determined is dependent on the relative global emission pattern
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JAPANESE ACTIVITIES IN SO2 AND NOX CONTROL
The paper reviews Japanese activities in SO2 and NOx control. From 1970 to 1985, energy use in Japan increased by 25%, and annual coal consumption rose from virtually nothing to 20 million tons, yet emissions of SO2 declined by 75% and NOx by 40%. While increases in hydroelectric...
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Characterization of N-glycosylation sites on the extracellular domain of NOX1/NADPH oxidase.
Matsumoto, Misaki; Katsuyama, Masato; Iwata, Kazumi; Ibi, Masakazu; Zhang, Jia; Zhu, Kai; Nauseef, William M; Yabe-Nishimura, Chihiro
2014-03-01
Extensive evidence demonstrates the pathophysiological importance of NOX1, the catalytic subunit of superoxide-generating enzyme NADPH oxidase, as a source of reactive oxygen species in nonphagocytic cells. However, the biochemical properties of NOX1 have not been extensively characterized due to a lack of specific immunological tools. We used a newly raised NOX1 polyclonal antibody to investigate posttranslational modifications of NOX1 overexpressed in cultured cells and in the colon, where endogenous NOX1 is highly expressed. Immunoblots of lysates from cells expressing NOX1 revealed a doublet of 56 and 60kDa accompanied by a broad band of 60-90kDa. Based on differential sensitivity to glycosidases, the doublet was identified as two high-mannose-type glycoforms of NOX1, whereas the broad band represented NOX1 with complex-type N-linked oligosaccharides. Deglycosylated NOX1 migrated at ~53kDa and N-glycosylation was demonstrated in NOX1 derived from both rat and human. Site-directed mutagenesis identified N-glycosylation sites at Asn(161) and Asn(241) on the extracellular loop of mouse NOX1. Elimination of N-glycosylation on NOX1 did not affect its electron transferase activity, protein stability, targeting to the cell surface, or localization in F-actin-positive membrane protrusions. Taken together, these data identify the two specific sites of N-linked glycosylation of murine NOX1 and demonstrate that they are not required for normal enzyme activity, protein stability, and membrane trafficking. As is true for NOX2, the contribution of glycosylation in NOX1 to its biologic function(s) merits further study. Copyright © 2013 Elsevier Inc. All rights reserved.
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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx.
Wojtal, Paul K; Miller, David J; O'Conner, Mary; Clark, Sydney C; Hastings, Meredith G
2016-12-20
Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence the oxidizing capacity of the atmosphere through interactions with ozone and hydroxyl radicals. The main sink of NOx is the formation and deposition of nitric acid, a component of acid rain and a bioavailable nutrient. NOx is emitted from a mixture of natural and anthropogenic sources, which vary in space and time. The collocation of multiple sources and the short lifetime of NOx make it challenging to quantitatively constrain the influence of different emission sources and their impacts on the environment. Nitrogen isotopes of NOx have been suggested to vary amongst different sources, representing a potentially powerful tool to understand the sources and transport of NOx. However, previous methods of collecting atmospheric NOx integrate over long (week to month) time spans and are not validated for the efficient collection of NOx in relevant, diverse field conditions. We report on a new, highly efficient field-based system that collects atmospheric NOx for isotope analysis at a time resolution between 30 min and 2 hr. This method collects gaseous NOx in solution as nitrate with 100% efficiency under a variety of conditions. Protocols are presented for collecting air in urban settings under both stationary and mobile conditions. We detail the advantages and limitations of the method and demonstrate its application in the field. Data from several deployments are shown to 1) evaluate field-based collection efficiency by comparisons with in situ NOx concentration measurements, 2) test the stability of stored solutions before processing, 3) quantify in situ reproducibility in a variety of urban settings, and 4) demonstrate the range of N isotopes of NOx detected in ambient urban air and on heavily traveled roadways.
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Variation of a Lightning NOx Indicator for National Climate Assessment
NASA Technical Reports Server (NTRS)
Koshak, William J.; McCaul, Eugene W., Jr.; Peterson, Harold S.; Vant-Hull, Brian
2014-01-01
During the past couple of years, an analysis tool was developed by the NASA Marshall Space Flight Center (MSFC) for the National Climate Assessment (NCA) program. The tool monitors and examines changes in lightning characteristics over the conterminous US (CONUS) on a continual basis. In this study, we have expanded the capability of the tool so that it can compute a new climate assessment variable that is called the Lightning NOx Indicator (LNI). Nitrogen oxides (NOx = NO + NO2) are known to indirectly influence our climate, and lightning NOx is the most important source of NOx in the upper troposphere (particularly in the tropics). The LNI is derived using Lightning Imaging Sensor (LIS) data and is computed by summing up the product of flash area x flash brightness over all flashes that occur in a particular region and period. Therefore, it is suggested that the LNI is a proxy to lightning NOx production. Specifically, larger flash areas are consistent with longer channel length and/or more energetic channels, and hence more NOx production. Brighter flashes are consistent with more energetic channels, and hence more NOx production. The location of the flash within the thundercloud and the optical scattering characteristics of the thundercloud are of course complicating factors. We analyze LIS data for the years 2003-2013 and provide geographical plots of the time-evolution of the LNI in order to determine if there are any significant changes or trends between like seasons, or from year to year.
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Correlating Engine NOx Emission with Biodiesel Composition
NASA Astrophysics Data System (ADS)
Jeyaseelan, Thangaraja; Mehta, Pramod Shankar
2017-06-01
Biodiesel composition comprising of saturated and unsaturated fatty acid methyl esters has a significant influence on its properties and hence the engine performance and emission characteristics. This paper proposes a comprehensive approach for composition-property-NOx emission analysis for biodiesel fuels and highlights the pathways responsible for such a relationship. Finally, a procedure and a predictor equation are developed for the assessment of biodiesel NOx emission from its composition details.
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Sera from cancer patients contain two oscillating ECTO-NOX activities with different period lengths
NASA Technical Reports Server (NTRS)
Wang, Sui; Morre, Dorothy M.; Morre, D. James
2003-01-01
ECTO-NOX protein's are cell surface-associated and growth-related hydroquinone oxidases with both protein disulfide-thiol interchange activity and the capacity to oxidize NAD(P)H. The activities of these ECTO-NOX proteins are not steady state but fluctuate to create a repeating pattern of oscillations. Two forms of ECTO-NOX activities have been distinguished. The constitutive ECTO-NOX (CNOX), is hormone responsive and refractory to quinone-site inhibitors. A tumor-associated NOX (tNOX) is unregulated, refractory to hormones and growth factors and responds to quinone-site inhibitors. CNOX proteins are widely distributed and exhibit oscillations in enzymatic activity with a period length of 24 min. tNOX proteins are cancer specific and exhibit oscillations with a period length of about 22 min. Our findings now demonstrate the presence of the novel oscillating tNOX activity in sera of patients with cancer whereas the constitutive NOX of non-cancer cells is present in sera of both cancer patients and healthy volunteers. We conclude that ECTO-NOX proteins in sera exhibit oscillatory characteristics similar to those of ECTO-NOX forms of the cell surface.
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Sensitivities of NOx transformation and the effects on surface ozone and nitrate
NASA Astrophysics Data System (ADS)
Lei, H.; Wang, J. X. L.
2014-02-01
As precursors to tropospheric ozone and nitrate, nitrogen oxide (NOx) in the present atmosphere and its transformation in response to emission and climate perturbations are studied by using the CAM-Chem model and air quality measurements from the National Emissions Inventory (NEI), Clean Air Status and Trends Network (CASTNET), and Environmental Protection Agency Air Quality System (EPA AQS). It is found that NOx transformations in present atmospheric conditions show different sensitivities over industrial and non-industrial regions. As a result, the surface ozone and nitrate formations can be divided into several regimes associated with the dominant emission types and relative levels of NOx and volatile organic compounds (VOC). Ozone production in industrial regions (the main NOx emission source areas) increases in warmer conditions and slightly decreases following an increase in NOx emissions due to NOx titration, which is opposite to the response in non-industrial regions. The ozone decrease following a temperature increase in non-industrial regions indicates that ozone production in regions that lack NOx emission sources may be sensitive to NOx transformation in remote source regions. The increase in NO2 from NOx titration over industrial regions results in an increase rate of total nitrate that remains higher than the increase rate of NOx emissions. The presented findings indicate that a change in the ozone concentration is more directly affected by changes in climate and precursor emissions, while a change in the nitrate concentration is affected by local ozone production types and their seasonal transfer. The sensitivity to temperature perturbations shows that a warmer climate accelerates the decomposition of odd nitrogen (NOy) during the night. As a result, the transformation rate of NOx to nitrate decreases. Examinations of the historical emissions and air quality records of a typical NOx-limited area, such as Atlanta and a VOC-limited area, such as Los
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40 CFR 96.142 - CAIR NOX allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... the 3 highest amounts of the unit's adjusted control period heat input for 2000 through 2004, with the adjusted control period heat input for each year calculated as follows: (A) If the unit is coal-fired... CAIR NOX Allowance Allocations § 96.142 CAIR NOX allowance allocations. (a)(1) The baseline heat input...
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40 CFR 75.70 - NOX mass emissions provisions.
Code of Federal Regulations, 2010 CFR
2010-07-01
... subpart to the extent that compliance is required by an applicable State or federal NOX mass emission...) For purposes of this subpart, the term “affected unit” shall mean any unit that is subject to a State...” shall mean the permitting authority under an applicable State or federal NOX mass emission reduction...
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NO(x) Concentrations in the Upper Troposphere as a Result of Lightning
NASA Technical Reports Server (NTRS)
Penner, Joyce E.
1998-01-01
Upper tropospheric NO(x) controls, in part, the distribution of ozone in this greenhouse-sensitive region of the atmosphere. Many factors control NO(x) in this region. As a result it is difficult to assess uncertainties in anthropogenic perturbations to NO from aircraft, for example, without understanding the role of the other major NO(x) sources in the upper troposphere. These include in situ sources (lightning, aircraft), convection from the surface (biomass burning, fossil fuels, soils), stratospheric intrusions, and photochemical recycling from HNO3. This work examines the separate contribution to upper tropospheric "primary" NO(x) from each source category and uses two different chemical transport models (CTMS) to represent a range of possible atmospheric transport. Because aircraft emissions are tied to particular pressure altitudes, it is important to understand whether those emissions are placed in the model stratosphere or troposphere and to assess whether the models can adequately differentiate stratospheric air from tropospheric air. We examine these issues by defining a point-by-point "tracer tropopause" in order to differentiate stratosphere from troposphere in terms of NO(x) perturbations. Both models predict similar zonal average peak enhancements of primary NO(x) due to aircraft (approx. = 10-20 parts per trillion by volume (pptv) in both January and July); however, the placement of this peak is primarily in a region of large stratospheric influence in one model and centered near the level evaluated as the tracer tropopause in the second. Below the tracer tropopause, both models show negligible NO(x) derived directly from the stratospheric source. Also, they predict a typically low background of 1 - 20 pptv NO(x) when tropospheric HNO3 is constrained to be 100 pptv of HNO3. The two models calculate large differences in the total background NO(x) (defined as the source of NO(x) from lightning + stratosphere + surface + HNO3) when using identical loss
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NOx Emissions Performance and Correlation Equations for a Multipoint LDI Injector
NASA Technical Reports Server (NTRS)
He, Zhuohui J.; Chang, Clarence T.; Follen, Caitlin E.
2014-01-01
Lean Direct Injection (LDI) is a combustor concept that reduces nitrogen oxides (NOx) emissions. This paper looks at a 3-zone multipoint LDI concept developed by Parker Hannifin Corporation. The concept was tested in a flame-tube test facility at NASA Glenn Research Center. Due to test facility limitations, such as inlet air temperature and pressure, the flame-tube test was not able to cover the full set of engine operation conditions. Three NOx correlation equations were developed based on assessing NOx emissions dependencies on inlet air pressure (P3), inlet air temperature (T3), and fuel air equivalence ratio (phi) to estimate the NOx emissions at the unreachable high engine power conditions. As the results, the NOx emissions are found to be a strong function of combustion inlet air temperature and fuel air equivalence ratio but a weaker function of inlet air pressure. With these three equations, the NOx emissions performance of this injector concept is calculated as a 66 percent reduction relative to the ICAO CAEP-6 standard using a 55:1 pressure-ratio engine cycle. Uncertainty in the NOx emissions estimation increases as the extrapolation range departs from the experimental conditions. Since maximum inlet air pressure tested was less than 50 percent of the full power engine inlet air pressure, a future experiment at higher inlet air pressure conditions is needed to confirm the NOx emissions dependency on inlet air pressure.
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NOx Emissions Performance and Correlation Equations for a Multipoint LDI Injector
NASA Technical Reports Server (NTRS)
He, Zhuohui Joe; Chang, Clarence T.; Follen, Caitlin E.
2015-01-01
Lean Direct Injection (LDI) is a combustor concept that reduces nitrogen oxides (NOx) emissions.This paper looks at a 3-zone multipoint LDI concept developed by Parker Hannifin Corporation. The concept was tested in a flame-tube test facility at NASA Glenn Research Center. Due to test facility limitations, such as inlet air temperature and pressure, the flame-tube test was not able to cover the full set of engine operation conditions. Three NOx correlation equations were developed based on assessing NOx emissions dependencies on inlet air pressure (P3), inlet air temperature (T3), and fuel air equivalence ratio(theta) to estimate the NOx emissions at the unreachable high engine power conditions. As the results, the NOx emissions are found to be a strong function of combustion inlet air temperature and fuel air equivalence ratio but a weaker function of inlet air pressure. With these three equations, the NOx emissions performance of this injector concept is calculated as a 66 reduction relative to the ICAO CAEP-6 standard using a 55:1 pressure-ratio engine cycle. Uncertainty in the NOx emissions estimation increases as the extrapolation range departs from the experimental conditions. Since maximum inlet air pressure tested was less than 50 of the full power engine inlet air pressure, a future experiment at higher inlet air pressure conditions is needed to confirm the NOx emissions dependency on inlet air pressure.
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NOx Emissions Performance and Correlation Equations for a Multipoint LDI Injector
NASA Technical Reports Server (NTRS)
He, Zhuohui J.; Chang, Clarence T.; Follen, Caitlin E.
2014-01-01
Lean Direct Injection (LDI) is a combustor concept that reduces nitrogen oxides (NOx) emissions. This paper looks at a 3-zone multipoint LDI concept developed by Parker Hannifin Corporation. The concept was tested in a flame-tube test facility at NASA Glenn Research Center. Due to test facility limitations, such as inlet air temperature and pressure, the flame-tube test was not able to cover the full set of engine operation conditions. Three NOx correlation equations were developed based on assessing NOx emissions dependencies on inlet air pressure (P3), inlet air temperature (T3), and fuel air equivalence ratio (?) to estimate the NOx emissions at the unreachable high engine power conditions. As the results, the NOx emissions are found to be a strong function of combustion inlet air temperature and fuel air equivalence ratio but a weaker function of inlet air pressure. With these three equations, the NOx emissions performance of this injector concept is calculated as a 66 percent reduction relative to the ICAO CAEP-6 standard using a 55:1 pressure-ratio engine cycle. Uncertainty in the NOx emissions estimation increases as the extrapolation range departs from the experimental conditions. Since maximum inlet air pressure tested was less than 50 percent of the full power engine inlet air pressure, a future experiment at higher inlet air pressure conditions is needed to confirm the NOx emissions dependency on inlet air pressure.
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Li-doped MgO as catalysts for oxidative coupling of methane: A positron annihilation study
NASA Astrophysics Data System (ADS)
Dai, G. H.; Yan, Q. J.; Wang, Y.; Liu, Q. S.
1991-08-01
Magnesium oxides intentionally doped with lithium (with a maximum Li content of 40 tool%) for use as catalysts for oxidative coupling of methane were characterized by means of positron annihilation. The positron lifetime spectra, which could be reasonably well interpreted within the framework of the well-known trapping model, depend on the amount of Li doping of the MgO suggesting that positrons are trapped at dispersed small Li 2CO 3 precipitates. Very similar dependencies on lithium doping of the C 2 selectivity and the positron trapping rate ϰ imply an intimate relationship between the concentration of [Li] 0-centers (also referred to as [Li +O -] centers) and the selective activity of Li/MgO during catalytic reactions.
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40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for CAIR NOX Ozone... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX Ozone...
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40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX Ozone... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX Ozone...
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40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX Ozone... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX Ozone...
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40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for CAIR NOX Ozone... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX Ozone...
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40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for CAIR NOX Ozone... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX Ozone...
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Optical and Electronic NOx Sensors for Applications in Mechatronics
Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A.; Wolter, Scott D.; Brown, April; Ricco, Mario
2009-01-01
Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling. PMID:22412315
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NOX2 As a Target for Drug Development: Indications, Possible Complications, and Progress
Diebold, Becky A.; Smith, Susan M.E.; Li, Yang
2015-01-01
Abstract Significance: NOX2 is important for host defense, and yet is implicated in a large number of diseases in which inflammation plays a role in pathogenesis. These include acute and chronic lung inflammatory diseases, stroke, traumatic brain injury, and neurodegenerative diseases, including Alzheimer's and Parkinson's Diseases. Recent Advances: Recent drug development programs have targeted several NOX isoforms that are implicated in a variety of diseases. The focus has been primarily on NOX4 and NOX1 rather than on NOX2, due, in part, to concerns about possible immunosuppressive side effects. Nevertheless, NOX2 clearly contributes to the pathogenesis of many inflammatory diseases, and its inhibition is predicted to provide a novel therapeutic approach. Critical Issues: Possible side effects that might arise from targeting NOX2 are discussed, including the possibility that such inhibition will contribute to increased infections and/or autoimmune disorders. The state of the field with regard to existing NOX2 inhibitors and targeted development of novel inhibitors is also summarized. Future Directions: NOX2 inhibitors show particular promise for the treatment of inflammatory diseases, both acute and chronic. Theoretical side effects include pro-inflammatory and autoimmune complications and should be considered in any therapeutic program, but in our opinion, available data do not indicate that they are sufficiently likely to eliminate NOX2 as a drug target, particularly when weighed against the seriousness of many NOX2-related indications. Model studies demonstrating efficacy with minimal side effects are needed to encourage future development of NOX2 inhibitors as therapeutic agents. Antioxid. Redox Signal. 23, 375–405. PMID:24512192
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Formaldehyde Production from Isoprene Oxidation Across NOx Regimes
NASA Technical Reports Server (NTRS)
Wolfe, G. M.; Kaiser, J.; Hanisco, T. F.; Keutsch, F. N.; de Gouw, J. A.; Gilman, J. B.; Graus, M.; Hatch, C. D.; Holloway, J.; Horowitz, L. W.;
2015-01-01
The chemical link between isoprene and formaldehyde (HCHO) is a strong, non-linear function of NOx (= 27 NO + NO2). This relationship is a linchpin for top-down isoprene emission inventory verification from orbital HCHO column observations. It is also a benchmark for overall mechanism performance with regard to VOC oxidation. Using a comprehensive suite of airborne in situ observations over the Southeast U.S., we quantify HCHO production across the urban-rural spectrum. Analysis of isoprene and its major first-generation oxidation products allows us to define both a "prompt" yield of HCHO (molecules of HCHO produced per molecule of freshly-emitted isoprene) and the background HCHO mixing ratio (from oxidation of longer-lived hydrocarbons). Over the range of observed NOx values (roughly 0.1 - 2 ppbv), the prompt yield increases by a factor of 3 (from 0.3 to 0.9), while background HCHO increases by more than a factor of 2 (from 1.5 to 3.3 ppbv). We apply the same method to evaluate the performance of both a global chemical transport model (AM3) and a measurement-constrained 0-D chemical box model. Both models reproduce the NOx dependence of the prompt HCHO yield, illustrating that models with updated isoprene oxidation mechanisms can adequately capture the link between HCHO and recent isoprene emissions. On the other hand, both models under-estimate background HCHO mixing ratios, suggesting missing HCHO precursors, inadequate representation of later-generation isoprene degradation and/or under-estimated hydroxyl radical concentrations. Moreover, we find that the total organic peroxy radical production rate is essentially independent of NOx, as the increase in oxidizing capacity with NOx is largely balanced by a decrease in VOC reactivity. Thus, the observed NOx dependence of HCHO mainly reflects the changing fate of organic peroxy radicals.
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A hybrid plasma-chemical system for high-NOx flue gas treatment
NASA Astrophysics Data System (ADS)
Chmielewski, Andrzej G.; Zwolińska, Ewa; Licki, Janusz; Sun, Yongxia; Zimek, Zbigniew; Bułka, Sylwester
2018-03-01
The reduction of high concentrations of NOx and SO2 from simulated flue gas has been studied. Our aim was to optimise energy consumption for NOx and SO2 removal from off-gases from a diesel generator using heavy fuel oil. A hybrid process: electron beam (EB) plasma and wet scrubber has been applied. A much higher efficiency of NOx and SO2 removal was achieved in comparison to dry, ammonia free, electron beam flue gas treatment (EBFGT). A recorded removal from a concentration of 1500 ppm NOx reached 49% at a low dose of 6.5 kGy, while only 2% NOx was removed at the same dose if EB only was applied. For SO2, removal efficiency at a dose of 6.5 kGy increased from 15% (EB only) to 84% when sea water was used as a wet scrubber agent for 700 ppm SO2. The results of this study indicate that EB combined with wet scrubber is a very promising technology to be applied for removal of high concentrations of NOx and SO2 emitted from diesel engines operated e.g. on cargo ships, which are the main sources of SO2 and NOx pollution along their navigation routes.
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A versatile MOF-based trap for heavy metal ion capture and dispersion.
Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli
2018-01-15
Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd 2+ -loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.
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Low NOx heavy fuel combustor concept program
NASA Technical Reports Server (NTRS)
White, D. J.; Kubasco, A. J.
1982-01-01
Three simulated coal gas fuels based on hydrogen and carbon monoxide were tested during an experimental evaluation with a rich lean can combustor: these were a simulated Winkler gas, Lurgi gas and Blue Water gas. All three were simulated by mixing together the necessary pure component species, to levels typical of fuel gases produced from coal. The Lurgi gas was also evaluated with ammonia addition. Fuel burning in a rich lean mode was emphasized. Only the Blue Water gas, however, could be operated in such fashion. This showed that the expected NOx signature form could be obtained, although the absolute values of NOx were above the 75 ppm goals for most operating conditions. Lean combustion produced very low NOx well below 75 ppm with the Winkler and Lurgi gases. In addition, these low levels were not significantly impacted by changes in operating conditions.
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40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the control...
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40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the control...
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40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the control...
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Development of the Aqueous Processes for Removing NOx from Flue Gases.
ERIC Educational Resources Information Center
Chappell, Gilford A.
A screening study was conducted to evaluate the capability of aqueous solutions to scrub NOx from the flue gases emitted by stationary power plants fired with fossil fuels. The report summarizes the findings of this laboratory program. The experimental program studied the following media for absorption of NOx from flue gases containing no NOx:…
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Lefort, I; Herreros, J M; Tsolakis, A
2014-02-18
The interactions between exhaust gas species and their effect (promotion or inhibition) on the light-off and activity of a diesel oxidation catalyst (DOC) for the removal of pollutants are studied, using actual engine exhaust gases from the combustion of diesel, alternative fuels (rapeseed methyl ester and gas-to-liquid fuel) and diesel/propane dual fuel combustion. The activity of the catalyst was recorded during a heating temperature ramp where carbon monoxide (CO) and hydrocarbon (HC) light-off curves were obtained. From the catalyst activity tests, it was found that the presence of species including CO, medium-heavy HC, alkenes, alkanes, and NOx and their concentration influence the catalyst ability to reduce CO and total HC emissions before release to the atmosphere. CO could inhibit itself and other species oxidation (e.g., light and medium-heavy hydrocarbons) while suffering from competitive adsorption with NO. Hydrocarbon species were also found to inhibit their own oxidation as well as CO through adsorption competition. On the other hand, NO2 was found to promote low temperature HC oxidation through its partial reduction, forming NO. The understanding of these exhaust species interactions within the DOC could aid the design of an efficient aftertreatment system for the removal of diesel exhaust pollutants.
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Catalyst system comprising a first catalyst system tethered to a supported catalyst
Angelici, Robert J.; Gao, Hanrong
1998-08-04
The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.
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40 CFR 97.512 - TR NOX Ozone Season allowance allocations to new units.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false TR NOX Ozone Season allowance... TR NOX Ozone Season Trading Program § 97.512 TR NOX Ozone Season allowance allocations to new units. (a) For each control period in 2012 and thereafter and for the TR NOX Ozone Season units in each...
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40 CFR 97.512 - TR NOX Ozone Season allowance allocations to new units.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false TR NOX Ozone Season allowance... TR NOX Ozone Season Trading Program § 97.512 TR NOX Ozone Season allowance allocations to new units. (a) For each control period in 2012 and thereafter and for the TR NOX Ozone Season units in each...
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40 CFR 97.512 - TR NOX Ozone Season allowance allocations to new units.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false TR NOX Ozone Season allowance... TR NOX Ozone Season Trading Program § 97.512 TR NOX Ozone Season allowance allocations to new units. (a) For each control period in 2012 and thereafter and for the TR NOX Ozone Season units in each...
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Gajos-Draus, Anna; Duda, Monika; Beręsewicz, Andrzej
2017-11-01
The superoxide-forming NADPH oxidase homologues, Nox1, Nox2, and Nox5, seem to mediate the pro-atherosclerotic vascular phenotype. The hydrogen peroxide-forming Nox4 afforded vascular protection, likely via NF-E2-related factor-2 (Nrf2) activation and/or Nox2 downregulation in transgenic mice. We hypothesized that oxidative stress in the intact vasculature involves, aside from the upregulation of the superoxide-forming Noxs, the downregulation of the Nox4/Nrf2 pathway. Guinea-pigs and rats were studied either in winter or in summer, and the streptozotocin diabetic rats in winter. Plasma nitrite, and superoxide production by isolated hearts were measured, while frozen tissues served in biochemical analyses. Summer in both species and diabetes in rats downregulated myocardial Nox4 while reciprocally upregulating Nox2 and Nox5 in guinea-pigs, and Nox2 in rats. Simultaneously, myocardial Nrf2 activity and the expression of the Nrf2-directed heme oxygenase-1 and endothelial NO synthase were reduced while activity of the nuclear factor κ B (NF- κ B) and the expression of NF- κ B-directed inducible NO synthase and the vascular cell adhesion molecule-1 were increased. Cardiac superoxide production was increased while plasma nitrite was decreased reciprocally. Analogous disregulation of Noxs, Nrf2, and NF- κ B, occurred in diabetic rat kidneys. Given the diversity of the experimental settings and the uniform pattern of the responses, we speculate that: (1) chronic vascular oxidative stress is a nonspecific (model-, species-, organ-independent) response involving the induction of Nox2 (and Nox5 in guinea-pigs) and the NF- κ B pathway, and the repression of Nox4 and the Nrf2 pathway; and (2) the systems Nox2-NF- κ B and Nox4-Nrf2 regulate each other negatively. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
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Quantifying the isotopic composition of NOx emission sources: An analysis of collection methods
NASA Astrophysics Data System (ADS)
Fibiger, D.; Hastings, M.
2012-04-01
We analyze various collection methods for nitrogen oxides, NOx (NO2 and NO), used to evaluate the nitrogen isotopic composition (δ15N). Atmospheric NOx is a major contributor to acid rain deposition upon its conversion to nitric acid; it also plays a significant role in determining air quality through the production of tropospheric ozone. NOx is released by both anthropogenic (fossil fuel combustion, biomass burning, aircraft emissions) and natural (lightning, biogenic production in soils) sources. Global concentrations of NOx are rising because of increased anthropogenic emissions, while natural source emissions also contribute significantly to the global NOx burden. The contributions of both natural and anthropogenic sources and their considerable variability in space and time make it difficult to attribute local NOx concentrations (and, thus, nitric acid) to a particular source. Several recent studies suggest that variability in the isotopic composition of nitric acid deposition is related to variability in the isotopic signatures of NOx emission sources. Nevertheless, the isotopic composition of most NOx sources has not been thoroughly constrained. Ultimately, the direct capture and quantification of the nitrogen isotopic signatures of NOx sources will allow for the tracing of NOx emissions sources and their impact on environmental quality. Moreover, this will provide a new means by which to verify emissions estimates and atmospheric models. We present laboratory results of methods used for capturing NOx from air into solution. A variety of methods have been used in field studies, but no independent laboratory verification of the efficiencies of these methods has been performed. When analyzing isotopic composition, it is important that NOx be collected quantitatively or the possibility of fractionation must be constrained. We have found that collection efficiency can vary widely under different conditions in the laboratory and fractionation does not vary
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Highly-basic large-pore zeolite catalysts for NOx reduction at low temperatures
Penetrante, Bernardino M.; Brusasco, Raymond M.; Merritt, Bernard T.; Vogtlin, George E.
2004-02-03
A high-surface-area (greater than 600 m2/g), large-pore (pore size diameter greater than 6.5 angstroms), basic zeolite having a structure such as an alkali metal cation-exchanged Y-zeolite is employed to convert NO.sub.x contained in an oxygen-rich engine exhaust to N.sub.2 and O.sub.2. Preferably, the invention relates to a two-stage method and apparatus for NO.sub.x reduction in an oxygen-rich engine exhaust such as diesel engine exhaust that includes a plasma oxidative stage and a selective reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and added hydrocarbons. The second stage employs a lean-NO.sub.x catalyst including the basic zeolite at relatively low temperatures to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
DOE; ORNL; NREL
1999-10-15
The Diesel Emission Control-Sulfur Effects (DECSE) is a joint government/industry program to determine the impact of diesel fuel sulfur levels on emission control systems whose use could lower emissions of nitrogen oxides (NOx) and particulate matter (PM) from on-highway trucks in the 2002--2004 model years. Phase 1 of the program was developed with the following objectives in mind: (1) evaluate the effects of varying the level of sulfur content in the fuel on the emission reduction performance of four emission control technologies; and (2) measure and compare the effects of up to 250 hours of aging on selected devices formore » multiple levels of fuel sulfur content. This interim report discusses the results of the DECSE test program that demonstrates the potential of NOx adsorber catalyst technology across the range of diesel engine operation with a fuel economy penalty less than 4%.« less
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CONTROL OF NOX EMISSIONS FROM U.S. COAL-FIRED ELECTRIC UTILITY BOILERS
The paper discusses the control of nitrogen oxide (NOx) emissions from U.S. coal-fired electric utility boilers. (NOTE: In general, NOx control technologies are categorized as being either primary or secondary control technologies. Primary technologies reduce the amount of NOx pr...
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Angiotensin II stimulates superoxide production in the thick ascending limb by activating NOX4
Hong, Nancy J.; Garvin, Jeffrey L.
2012-01-01
Angiotensin II (ANG II) stimulates production of superoxide (O2−) by NADPH oxidase (NOX) in medullary thick ascending limbs (TALs). There are three isoforms of the catalytic subunit (NOX1, 2, and 4) known to be expressed in the kidney. We hypothesized that NOX2 mediates ANG II-induced O2− production by TALs. To test this, we measured NOX1, 2, and 4 mRNA and protein by RT-PCR and Western blot in TAL suspensions from rats and found three catalytic subunits expressed in the TAL. We measured O2− production using a lucigenin-based assay. To assess the contribution of NOX2, we measured ANG II-induced O2− production in wild-type and NOX2 knockout mice (KO). ANG II increased O2− production by 346 relative light units (RLU)/mg protein in the wild-type mice (n = 9; P < 0.0007 vs. control). In the knockout mice, ANG II increased O2− production by 290 RLU/mg protein (n = 9; P < 0.007 vs. control). This suggests that NOX2 does not contribute to ANG II-induced O2− production (P < 0.6 WT vs. KO). To test whether NOX4 mediates the effect of ANG II, we selectively decreased NOX4 expression in rats using an adenovirus that expresses NOX4 short hairpin (sh)RNA. Six to seven days after in vivo transduction of the kidney outer medulla, NOX4 mRNA was reduced by 77%, while NOX1 and NOX2 mRNA was unaffected. In control TALs, ANG II stimulated O2− production by 96%. In TALs transduced with NOX4 shRNA, ANG II-stimulated O2− production was not significantly different from the baseline. We concluded that NOX4 is the main catalytic isoform of NADPH oxidase that contributes to ANG II-stimulated O2− production by TALs. PMID:22875785
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Catalyst system comprising a first catalyst system tethered to a supported catalyst
Angelici, R.J.; Gao, H.
1998-08-04
The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilication, olefin oxidation, isomerization, hydrocyanidation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical. 2 figs.
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NOx Sensor for Direct Injection Emission Control
DOE Office of Scientific and Technical Information (OSTI.GOV)
Betteridge, William J
2006-02-28
The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness andmore » durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development
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Estimation of NOx Production from Terrestrial Gamma-ray Flashes
NASA Astrophysics Data System (ADS)
Cramer, E. S.; Briggs, M. S.; Liu, N.; Mailyan, B.; Rassoul, H.; Dwyer, J. R.
2016-12-01
The motivation of this work is to understand the effects of TGFs on the ozone layer. One of the main ozone-destroying mechanisms is the production of NOx in the stratospheric region. We first review the mechanisms for NOx production in this region, specifically looking at the global rate produced by lightning. Terrestrial Gamma-ray Flashes, with runaway electron avalanches and the subsequent bremsstrahlung gamma rays, produce atmospheric ionization at all altitudes of the atmosphere. TGFs might have a greater impact on the ozone concentration in the stratosphere since they directly produce ionization and thus NOx in the ozone layer. In order to study the effect from TGFs, we use the runaway electron avalanche model (REAM) to simulate a typical TGF. The photons are then transported through Earth's atmosphere, where they deposit some of their energy as ionization in the ozone layer. We then calculate the number of NOx molecules produced by considering the average energy required to produce one electron-ion pair (W = 35 eV). The W factor has been experimentally quantified and is constant for various types of radiation and over large energy ranges and electric fields. Finally, the effect of TGF NOx production is estimated using the global annual rate of TGFs.
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NOX2 protects against progressive lung injury and multiple organ dysfunction syndrome.
Whitmore, Laura C; Goss, Kelli L; Newell, Elizabeth A; Hilkin, Brieanna M; Hook, Jessica S; Moreland, Jessica G
2014-07-01
Systemic inflammatory response syndrome (SIRS) is a common clinical condition in patients in intensive care units that can lead to complications, including multiple organ dysfunction syndrome (MODS). MODS carries a high mortality rate, and it is unclear why some patients resolve SIRS, whereas others develop MODS. Although oxidant stress has been implicated in the development of MODS, several recent studies have demonstrated a requirement for NADPH oxidase 2 (NOX2)-derived oxidants in limiting inflammation. We recently demonstrated that NOX2 protects against lung injury and mortality in a murine model of SIRS. In the present study, we investigated the role of NOX2-derived oxidants in the progression from SIRS to MODS. Using a murine model of sterile systemic inflammation, we observed significantly greater illness and subacute mortality in gp91(phox-/y) (NOX2-deficient) mice compared with wild-type mice. Cellular analysis revealed continued neutrophil recruitment to the peritoneum and lungs of the NOX2-deficient mice and altered activation states of both neutrophils and macrophages. Histological examination showed multiple organ pathology indicative of MODS in the NOX2-deficient mice, and several inflammatory cytokines were elevated in lungs of the NOX2-deficient mice. Overall, these data suggest that NOX2 function protects against the development of MODS and is required for normal resolution of systemic inflammation. Copyright © 2014 the American Physiological Society.
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Towards the Rational Design of Nanoparticle Catalysts
NASA Astrophysics Data System (ADS)
Dash, Priyabrat
stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted). The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O 3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).
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Lee, Chun W; Srivastava, Ravi K; Ghorishi, S Behrooz; Hastings, Thomas W; Stevens, Frank M
2004-12-01
Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NOx reduction, promote the formation of oxidized mercury (Hg2+). The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg0) oxidation. Bench-scale experiments were conducted to investigate Hg0 oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO2) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO2 in the flue gases on Hg0 oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg0 to Hg2+ under SCR reaction conditions. The importance of HCl for Hg0 oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg0 oxidation occurring across the SCR reactors in the field.
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40 CFR 97.50 - NOX Allowance Tracking System accounts.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false NOX Allowance Tracking System accounts. 97.50 Section 97.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Tracking System § 97.50 NOX Allowance Tracking System accounts. (a) Nature and function of compliance...
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40 CFR 97.50 - NOX Allowance Tracking System accounts.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false NOX Allowance Tracking System accounts. 97.50 Section 97.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Tracking System § 97.50 NOX Allowance Tracking System accounts. (a) Nature and function of compliance...
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Measurement of NOx fluxes from a tall tower in Beijing
NASA Astrophysics Data System (ADS)
Squires, Freya; Dunmore, Rachel; Lewis, Alastair; Vaughan, Adam; Mullinger, Neil; Nemitz, Eiko; Wild, Oliver; Zhang, Qiang; Hamilton, Jacqueline; Lee, James; Fu, Pingqing
2017-04-01
Nitrogen Oxides (NOx, the sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2)) are significant anthropogenic pollutants emitted from most combustion processes. NOx is a precursor species to the formation of O3 and secondary aerosols and, in high concentrations, NO2 can have adverse effects on human health through action as a respiratory irritant. For these reasons, there has been increased focus on improving NOx emissions inventories, typically developed using 'bottom-up' estimates of emissions from their sources, which are used to predict current and future air quality and to guide abatement strategy. Recent studies have shown a discrepancy between NOx inventories and measured NOx emissions for UK cities, highlighting the limitations of bottom-up emissions inventories and the importance of accurate measurement data to improve the estimates. Similarly, inventories in China are associated with large uncertainties and are rapidly changing with time in response to economic development and new environmental regulation. Here, we present data collected as part of the Air Pollutants in Beijing (AIRPOLL-Beijing) campaign from an urban site located at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP, CAS) (39˚ 58'28"N, 116˚ 22'16"E) in central Beijing. NOx concentrations were measured using a state-of-the-art chemiluminescence instrument, sampling from an inlet at 100 metres on a meteorological tower. Measurements at 5 Hz coupled with wind vector data measured by a sonic anemometer located at the same height as the inlet allowed NOx emission fluxes to be calculated using the eddy covariance method. Measurements were made during the period 11/11/2016 - 10/12/2016 and compared to existing emission estimates from The Multi-resolution Emission Inventory for China (MEIC) inventory. It is anticipated that this work will be used to evaluate the accuracy of emissions inventories for Beijing, to develop improved emissions estimates and thus provide
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40 CFR 97.521 - Recordation of TR NOX Ozone Season allowance allocations and auction results.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Recordation of TR NOX Ozone Season... SO2 TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.521 Recordation of TR NOX Ozone Season... Ozone Season source's compliance account the TR NOX Ozone Season allowances allocated to the TR NOX...
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40 CFR 97.521 - Recordation of TR NOX Ozone Season allowance allocations and auction results.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Recordation of TR NOX Ozone Season... SO2 TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.521 Recordation of TR NOX Ozone Season... Ozone Season source's compliance account the TR NOX Ozone Season allowances allocated to the TR NOX...
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40 CFR 97.521 - Recordation of TR NOX Ozone Season allowance allocations and auction results.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Recordation of TR NOX Ozone Season... SO2 TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.521 Recordation of TR NOX Ozone Season... Ozone Season source's compliance account the TR NOX Ozone Season allowances allocated to the TR NOX...
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Ozone production efficiency (OPE) can be defined as the number of ozone (O3) molecules photochemically produced by a molecule of NOx (NO + NO2) before it is lost from the NOx - O3 cycle. Here, we consider observational and modeling techniques to evaluate various operational defi...
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DIESEL NOX CONTROL APPLICATION
The paper gives results of a project to design, develop, and demonstrate a diesel engine nitrogen oxide (NOx) and particulate matter (PM) control package that will meet the U.S. Navy's emission control requirements. (NOTE: In 1994, EPA issued a Notice for Proposed Rule Making (NP...
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Zhang, Runduo; Liu, Ning; Lei, Zhigang; Chen, Biaohua
2016-03-23
In this review we focus on the catalytic removal of a series of N-containing exhaust gases with various valences, including nitriles (HCN, CH3CN, and C2H3CN), ammonia (NH3), nitrous oxide (N2O), and nitric oxides (NO(x)), which can cause some serious environmental problems, such as acid rain, haze weather, global warming, and even death. The zeolite catalysts with high internal surface areas, uniform pore systems, considerable ion-exchange capabilities, and satisfactory thermal stabilities are herein addressed for the corresponding depollution processes. The sources and toxicities of these pollutants are introduced. The important physicochemical properties of zeolite catalysts, including shape selectivity, surface area, acidity, and redox ability, are described in detail. The catalytic combustion of nitriles and ammonia, the direct catalytic decomposition of N2O, and the selective catalytic reduction and direct catalytic decomposition of NO are systematically discussed, involving the catalytic behaviors as well as mechanism studies based on spectroscopic and kinetic approaches and molecular simulations. Finally, concluding remarks and perspectives are given. In the present work, emphasis is placed on the structure-performance relationship with an aim to design an ideal zeolite-based catalyst for the effective elimination of harmful N-containing compounds.
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40 CFR 96.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Submission of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Transfers § 96.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR...
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40 CFR 96.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Submission of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Transfers § 96.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR...
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40 CFR 96.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Submission of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Transfers § 96.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR...
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40 CFR 96.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Submission of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Transfers § 96.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR...
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40 CFR 96.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Recordation of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Tracking System § 96.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in...
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40 CFR 96.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Recordation of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Tracking System § 96.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in...
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40 CFR 96.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Recordation of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Tracking System § 96.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in...
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40 CFR 96.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Recordation of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Tracking System § 96.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in...
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40 CFR 96.360 - Submission of CAIR NOX Ozone Season allowance transfers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Submission of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Transfers § 96.360 Submission of CAIR NOX Ozone Season allowance transfers. A CAIR authorized account representative seeking recordation of a CAIR...
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40 CFR 96.353 - Recordation of CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Recordation of CAIR NOX Ozone Season... STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Tracking System § 96.353 Recordation of CAIR NOX Ozone Season allowance allocations. (a) By September 30, 2007, the Administrator will record in...
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Reconciling NOx emissions reductions and ozone trends in ...
Dynamic evaluation seeks to assess the ability of photochemical models to replicate changes in air quality as emissions and other conditions change. When a model fails to replicate an observed change, a key challenge is to discern whether the discrepancy is caused by errors in meteorological simulations, errors in emission magnitudes and changes, or inaccurate responses of simulated pollutant concentrations to emission changes. In this study, the Community Multiscale Air Quality (CMAQ) model is applied to simulate the ozone (O3) change after the NOx SIP Call and mobile emission controls substantially reduced nitrogen oxides (NOx) emissions in the eastern U.S. from 2002 to 2006. For both modeled and observed O3, changes in episode average daily maximal 8-h O3 were highly correlated (R2 = 0.89) with changes in the 95th percentile, although the magnitudes of reductions increased nonlinearly at high percentile O3 concentrations. Observed downward changes in mean NOx (−11.6 to −2.5 ppb) and 8-h O3 (−10.4 to −4.7 ppb) concentrations in metropolitan areas in the NOx SIP Call region were under-predicted by 31%–64% and 26%–66%, respectively. The under-predicted O3 improvements in the NOx SIP Call region could not be explained by adjusting for temperature biases in the meteorological input, or by considering uncertainties in the chemical reaction rate constants. However, the under-prediction in O3 improvements could be alleviated by 5%–31% by constraining NO
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Valente, Anthony J.; Yoshida, Tadashi; Murthy, Subramanyam N.; Sakamuri, Siva S. V. P.; Katsuyama, Masato; Clark, Robert A.; Delafontaine, Patrice
2012-01-01
The redox-sensitive transcription factors NF-κB and activator protein-1 (AP-1) are critical mediators of ANG II signaling. The promitogenic and promigratory factor interleukin (IL)-18 is an NF-κB- and AP-1-responsive gene. Therefore, we investigated whether ANG II-mediated smooth muscle cell (SMC) migration and proliferation involve IL-18. ANG II induced rat carotid artery SMC migration and proliferation and IL-18 and metalloproteinase (MMP)-9 expression via ANG II type 1 (AT1) receptor. ANG II-induced superoxide generation, NF-κB and AP-1 activation, and IL-18 and MMP-9 induction were all markedly attenuated by losartan, diphenyleneiodonium chloride (DPI), and Nox1 knockdown. Similar to ANG II, addition of IL-18 also induced superoxide generation, activated NF-κB and AP-1, and stimulated SMC migration and proliferation, in part via Nox1, and both ANG II and IL-18 induced NOX1 transcription in an AP-1-dependent manner. AT1 physically associates with Nox1 in SMC, and ANG II enhanced this binding. Interestingly, exogenous IL-18 neither induced AT1 binding to Nox1 nor enhanced the ANG II-induced increase in AT1/Nox1 binding. Importantly, IL-18 knockdown, or pretreatment with IL-18 neutralizing antibodies, or IL-18 binding protein, all attenuated the migratory and mitogenic effects of ANG II. Continuous infusion of ANG II for 7 days induced carotid artery hyperplasia in rats via AT1 and was associated with increased AT1/Nox1 binding (despite lower AT1 levels); increased DPI-inhibitable superoxide production; increased phospho-IKKβ, JNK, p65, and c-Jun; and induction of IL-18 and MMP-9 in endothelium-denuded carotid arteries. These results indicate that IL-18 amplifies the ANG II-induced, redox-dependent inflammatory cascades by activating similar promitogenic and promigratory signal transduction pathways. The ANG II/Nox1/IL-18 pathway may be critical in hyperplastic vascular diseases, including atherosclerosis and restenosis. PMID:22636674
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Aiding and abetting roles of NOX oxidases in cellular transformation
Block, Karen; Gorin, Yves
2013-01-01
NADPH oxidases of the NADPH oxidase (NOX) family are dedicated reactive oxygen species-generating enzymes that broadly and specifically regulate redox-sensitive signalling pathways that are involved in cancer development and progression. They act at specific cellular membranes and microdomains through the activation of oncogenes and the inactivation of tumour suppressor proteins. In this Review, we discuss primary targets and redox-linked signalling systems that are influenced by NOX-derived ROS, and the biological role of NOX oxidases in the aetiology of cancer. PMID:22918415
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NOx reduction through combustion optimization at PEPCO`s Potomac River Station
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cramer, D.S.; Williams, S.E.; Watkins, J.T.
1995-06-01
This paper describes the work done under EPRI Project RP 3383 at Potomac River Station to reduce NOx emissions by adjusting boiler controls. it details the method followed by PEPCO and Lehigh engineers to achieve a 35% reduction in average NOx emissions over a one-month extended test. Parameters that had the largest effect on NOx are discussed. A description of instruments installed to better monitor and control combustion is included.
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Modeling of nitrogen oxides (NO(x)) concentrations resulting from ships at berth.
Abdul-Wahab, Sabah A; Elkamel, Ali; Al Balushi, Abdullah S; Al-Damkhi, Ali M; Siddiqui, Rafiq A
2008-12-01
Oxides of nitrogen (NO(x)) emissions from ships (marine vessels) contribute to poor air quality that negatively impacts public health and communities in coastal areas and far inland. These emissions often excessively harm human health, environment, wildlife habituates, and quality of life of communities and indigenous of people who live near ports. This study was conducted to assess the impact of NO(x) emissions origination from ships at berth on a nearby community. It was undertaken at Said Bin Sultan Naval base in Wullayat Al-Mussana (Sultanate of Oman) during the year 2005. The Industrial Source Complex Short Term (ISCST) model was adopted to determine the dispersion of NO(x) into port and beyond into surrounding urban areas. The hourly and monthly contours (isopleths) of NO(x) concentrations in and around the port were plotted. The results were analyzed to determine the affected area and the level of NO(x) concentrations. The highest concentration points in the studied area were also identified. The isopleths of NO(x) indicated that most shipping emissions of NO(x) occur at the port can be transported over land. The output results can help to derive advice of recommendations ships operators and environmentalists to take the correct decision to prevent workers and surrounded environment from pollution.
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TRPC3-Nox2 complex mediates doxorubicin-induced myocardial atrophy
Shimauchi, Tsukasa; Numaga-Tomita, Takuro; Ito, Tomoya; Nishimura, Akiyuki; Matsukane, Ryosuke; Oda, Sayaka; Hoka, Sumio; Ide, Tomomi; Koitabashi, Norimichi; Uchida, Koji; Sumimoto, Hideki; Mori, Yasuo
2017-01-01
Myocardial atrophy is a wasting of cardiac muscle due to hemodynamic unloading. Doxorubicin is a highly effective anticancer agent but also induces myocardial atrophy through a largely unknown mechanism. Here, we demonstrate that inhibiting transient receptor potential canonical 3 (TRPC3) channels abolishes doxorubicin-induced myocardial atrophy in mice. Doxorubicin increased production of ROS in rodent cardiomyocytes through hypoxic stress–mediated upregulation of NADPH oxidase 2 (Nox2), which formed a stable complex with TRPC3. Cardiomyocyte-specific expression of TRPC3 C-terminal minipeptide inhibited TRPC3-Nox2 coupling and suppressed doxorubicin-induced reduction of myocardial cell size and left ventricular (LV) dysfunction, along with its upregulation of Nox2 and oxidative stress, without reducing hypoxic stress. Voluntary exercise, an effective treatment to prevent doxorubicin-induced cardiotoxicity, also downregulated the TRPC3-Nox2 complex and promoted volume load–induced LV compliance, as demonstrated in TRPC3-deficient hearts. These results illustrate the impact of TRPC3 on LV compliance and flexibility and, focusing on the TRPC3-Nox2 complex, provide a strategy for prevention of doxorubicin-induced cardiomyopathy. PMID:28768915
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NASA Astrophysics Data System (ADS)
Li, Ming-yuan; Guo, Rui-tang; Hu, Chang-xing; Sun, Peng; Pan, Wei-guo; Liu, Shu-ming; Sun, Xiao; Liu, Shuai-wei; Liu, Jian
2018-04-01
The deactivation of SCR catalyst caused by K species contained in the fly ash would suppress its DeNOx performance. In this study, it was manifested that the modification of Ce/TiO2 catalyst with P could enhance its K tolerance. To understand the promotion mechanism, the fresh and poisoned catalyst samples were subjected to the characterization techniques including BET, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFT. The results elucidated that the introduction of P species could increase the reducibility of Ce species and generate more surface chemisorbed oxygen, along with the strengthened surface acidity for NH3 adsorption. It seemed that the NH3-SCR reaction mechanism over Ce/TiO2 catalyst was a combination of L-H mechanism (<200 °C) and E-R mechanism (≥200 °C). After the addition of P species, the NO oxidation over Ce/TiO2 catalyst was also accelerated, accompanied by the broadened temperature window for the NH3-SCR reaction under the control of L-H mechanism. The promoted NH3 species adsorption and the generated more NO2 over P-Ce/TiO2 catalyst were conducive to the NH3-SCR reaction through L-H pathway, which might be the primary reason for its good K resistance.
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Promoted decomposition of NOx in automotive diesel-like exhausts by electro-catalytic honeycombs.
Huang, Ta-Jen; Chiang, De-Yi; Shih, Chi; Lee, Cheng-Chin; Mao, Chih-Wei; Wang, Bo-Chung
2015-03-17
NO and NO2 (collectively called NOx) are major air pollutants in automotive emissions. More effective and easier treatments of NOx than those achieved by the present methods can offer better protection of human health and higher fuel efficiency that can reduce greenhouse gas emissions. However, currently commercialized technologies for automotive NOx emission control cannot effectively treat diesel-like exhausts with high NOx concentrations. Thus, exhaust gas recirculation (EGR) has been used extensively, which reduces fuel efficiency and increases particulate emission considerably. Our results show that the electro-catalytic honeycomb (ECH) promotes the decomposition of NOx to nitrogen and oxygen, without consuming reagents or other resources. NOx can be converted to nitrogen and oxygen almost completely. The ECHs are shown to effectively remove NOx from gasoline-fueled diesel-like exhausts. A very high NO concentration is preferred in the engine exhaust, especially during engine cold-start. Promoted NOx decomposition (PND) technology for real-world automotive applications is established in this study by using the ECH. With PND, EGR is no longer needed. Diesel-like engines can therefore achieve superior fuel efficiency, and all major automotive pollutants can be easily treated due to high concentration of oxygen in the diesel-like exhausts, leading to zero pollution.
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Parse, simulation, and prediction of NOx emission across the Midwestern United States
NASA Astrophysics Data System (ADS)
Fang, H.; Michalski, G. M.; Spak, S.
2017-12-01
Accurately constraining N emissions in space and time has been a challenge for atmospheric scientists. It has been suggested that 15N isotopes may be a way of tracking N emission sources across various spatial and temporal scales. However, the complexity of multiple N sources that can quickly change in intensity has made this a difficult problem. We have used a SMOKE emission model to parse NOx emission across the Midwestern United States for a one-year simulation. An isotope mass balance methods was used to assign 15N values to road, non-road, point, and area sources. The SMOKE emissions and isotope mass balance were then combined to predict the 15N of NOx emissions (Figure 1). This ^15N of NOx emissions model was then incorporated into CMAQ to assess the role of transport and chemistry would impact the 15N value of NOx due to mixing and removal processes. The predicted 15N value of NOx was compared to those in recent measurements of NOx and atmospheric nitrate.
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On-board ammonia generation and exhaust after treatment system using same
Driscoll, Josh; Robel, Wade J.; Brown, Cory A.; Urven, Jr., Roger L.
2010-03-30
Often NOx selective catalysts that use ammonia to reduce NOx within exhaust to a harmless gas require on-board storage of ammonia which can be hazardous and inconvenient. In order to generate ammonia in exhaust, the present disclosure increases a NOx concentration in exhaust from at least one combustion chamber, at least in part, by injecting fuel in a predetermined increased NOx generation sequence that includes a first injection during non-auto ignition conditions and a second injection during auto ignition conditions. At least a portion of the NOx is converted to ammonia by passing at least a portion of the exhaust with the increased NOx concentration over an ammonia-producing catalyst.
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Camargo, Livia L; Harvey, Adam P; Rios, Francisco J; Tsiropoulou, Sofia; Da Silva, Renée de Nazaré Oliveira; Cao, Zhenbo; Graham, Delyth; McMaster, Claire; Burchmore, Richard J; Hartley, Richard C; Bulleid, Neil; Montezano, Augusto C; Touyz, Rhian M
2018-07-01
Vascular Nox (NADPH oxidase)-derived reactive oxygen species and endoplasmic reticulum (ER) stress have been implicated in hypertension. However, relationships between these processes are unclear. We hypothesized that Nox isoforms localize in a subcellular compartment-specific manner, contributing to oxidative and ER stress, which influence the oxidative proteome and vascular function in hypertension. Nox compartmentalization (cell fractionation), O 2 - (lucigenin), H 2 O 2 (amplex red), reversible protein oxidation (sulfenylation), irreversible protein oxidation (protein tyrosine phosphatase, peroxiredoxin oxidation), and ER stress (PERK [protein kinase RNA-like endoplasmic reticulum kinase], IRE1α [inositol-requiring enzyme 1], and phosphorylation/oxidation) were studied in spontaneously hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). VSMC proliferation was measured by fluorescence-activated cell sorting, and vascular reactivity assessed in stroke-prone SHR arteries by myography. Noxs were downregulated by short interfering RNA and pharmacologically. In SHR, Noxs were localized in specific subcellular regions: Nox1 in plasma membrane and Nox4 in ER. In SHR, oxidative stress was associated with increased protein sulfenylation and hyperoxidation of protein tyrosine phosphatases and peroxiredoxins. Inhibition of Nox1 (NoxA1ds), Nox1/4 (GKT137831), and ER stress (4-phenylbutyric acid/tauroursodeoxycholic acid) normalized SHR vascular reactive oxygen species generation. GKT137831 reduced IRE1α sulfenylation and XBP1 (X-box binding protein 1) splicing in SHR. Increased VSMC proliferation in SHR was normalized by GKT137831, 4-phenylbutyric acid, and STF083010 (IRE1-XBP1 disruptor). Hypercontractility in the stroke-prone SHR was attenuated by 4-phenylbutyric acid. We demonstrate that protein hyperoxidation in hypertension is associated with oxidative and ER stress through upregulation of plasmalemmal-Nox1 and ER-Nox4. The IRE1-XBP1 pathway of the ER stress
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NOx profile around a signalized intersection of busy roadway
NASA Astrophysics Data System (ADS)
Kim, Kyung Hwan; Lee, Seung-Bok; Woo, Sung Ho; Bae, Gwi-Nam
2014-11-01
The NOx pollution profile around a signalized intersection of a busy roadway was investigated to understand the effect of traffic control on urban air pollution. Traffic flow patterns were classified into three categories of quasi-cruising, a combination of deceleration and acceleration, and a combination of deceleration, idling, and acceleration. The spatial distribution of air pollution levels around an intersection could be represented as a quasi-normal distribution, whose peak height was aggravated by increased emissions due to transient driving patterns. The peak concentration of NOx around the signalized intersection for the deceleration, idling, and acceleration category was five times higher than that for the quasi-cruising category. Severe levels of NOx pollution tailed off approximately 400 m from the center of the intersection. Approximately 200-1000 ppb of additional NOx was observed when traffic was decelerating, idling, and accelerating within the intersection zone, resulting in high exposure levels for pedestrians around the intersection. We propose a fluctuating horizontal distribution of motor vehicle-induced air pollutants as a function of time.
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Catalytic Combustion for Ultra-Low NOx Hydrogen Turbines
DOE Office of Scientific and Technical Information (OSTI.GOV)
Etemad, Shahrokh; Baird, Benjamin; Alavandi, Sandeep
2011-06-30
Precision Combustion, Inc., (PCI) in close collaboration with Solar Turbines, Incorporated, has developed and demonstrated a combustion system for hydrogen fueled turbines that reduces NOx to low single digit level while maintaining or improving current levels of efficiency and eliminating emissions of carbon dioxide. Full scale Rich Catalytic Hydrogen (RCH1) injector was developed and successfully tested at Solar Turbines, Incorporated high pressure test facility demonstrating low single digit NOx emissions for hydrogen fuel in the range of 2200F-2750F. This development work was based on initial subscale development for faster turnaround and reduced cost. Subscale testing provided promising results for 42%more » and 52% H2 with NOx emissions of less than 2 ppm with improved flame stability. In addition, catalytic reactor element testing for substrate oxidation, thermal cyclic injector testing to simulate start-stop operation in a gas turbine environment, and steady state 15 atm. operation testing were performed successfully. The testing demonstrated stable and robust catalytic element component life for gas turbine conditions. The benefit of the catalytic hydrogen combustor technology includes capability of delivering near-zero NOx without costly post-combustion controls and without requirement for added sulfur control. In addition, reduced acoustics increase gas turbine component life. These advantages advances Department of Energy (DOE’s) objectives for achievement of low single digit NOx emissions, improvement in efficiency vs. postcombustion controls, fuel flexibility, a significant net reduction in Integrated Gasification Combined Cycle (IGCC) system net capital and operating costs, and a route to commercialization across the power generation field from micro turbines to industrial and utility turbines.« less
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The challenge to NOx emission control for heavy-duty diesel vehicles in China
NASA Astrophysics Data System (ADS)
Wu, Y.; Zhang, S. J.; Li, M. L.; Ge, Y. S.; Shu, J. W.; Zhou, Y.; Xu, Y. Y.; Hu, J. N.; Liu, H.; Fu, L. X.; He, K. B.; Hao, J. M.
2012-10-01
China's new "Twelfth Five-Year Plan" set a target for total NOx emission reduction of 10% for the period of 2011-2015. Heavy-duty diesel vehicles (HDDVs) have been considered a major contributor to NOx emissions in China. Beijing initiated a comprehensive vehicle test program in 2008. This program included a sub-task for measuring on-road emission profiles of hundreds of HDDVs using portable emission measurement systems (PEMS). The major finding is that neither the on-road distance-specific (g km-1) nor brake-specific (g kWh-1) NOx emission factors for diesel buses and heavy-duty diesel trucks improved in most cases as emission standards became more stringent. For example, the average NOx emission factors for Euro II, Euro III and Euro IV buses are 11.3 ± 3.3 g km-1, 12.5 ± 1.3 g km-1, and 11.8 ± 2.0 g km-1, respectively. No statistically significant difference in NOx emission factors was observed between Euro II and III buses. Even for Euro IV buses equipped with SCR systems, the NOx emission factors are similar to Euro III buses. The data regarding real-time engine performance of Euro IV buses suggest the engine certification cycles did not reflect their real-world operating conditions. These new on-road test results indicate that previous estimates of total NOx emissions for HDDV fleet may be significantly underestimated. The new estimate in total NOx emissions for the Beijing HDDV fleet in 2009 is 37.0 Gg, an increase of 45% compared to the previous study. Further, we estimate that the total NOx emissions for the national HDDV fleet in 2009 are approximately 4.0 Tg, higher by 1.0 Tg (equivalent to 18% of total NOx emissions for vehicle fleet in 2009) than that estimated in the official report. This would also result in 4% increase in estimation of national anthropogenic NOx emissions. More effective control measures (such as promotion of CNG buses and a new in-use compliance testing program) are urged to secure the goal of total NOx mitigation for the HDDV
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Optical and Electronic NO(x) Sensors for Applications in Mechatronics.
Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A; Wolter, Scott D; Brown, April; Ricco, Mario
2009-01-01
Current production and emerging NO(x) sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NO(x) show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NO(x) in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NO(x) sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling.
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DEVELOPMENT AND DEMONSTRATION OF NOVEL LOW-NOx BURNERS IN THE STEEL INDUSTRY
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cygan, David
Gas Technology Institute (GTI), together with Hamworthy Peabody Combustion Incorporated (formerly Peabody Engineering Corporation), the University of Utah, and Far West Electrochemical have developed and demonstrated an innovative combustion system suitable for natural gas and coke-oven gas firing within the steel industry. The combustion system is a simple, low-cost, energy-efficient burner that can reduce NOx by more than 75%. The U.S. steel industry needs to address NOx control at its steelmaking facilities. A significant part of NOx emissions comes from gas-fired boilers. In steel plants, byproduct gases – blast furnace gas (BFG) and coke-oven gas (COG) – are widely usedmore » together with natural gas to fire furnaces and boilers. In steel plants, natural gas can be fired together with BFG and COG, but, typically, the addition of natural gas raises NOx emissions, which can already be high because of residual fuel-bound nitrogen in COG. The Project Team has applied its expertise in low-NOx burners to lower NOx levels for these applications by combining advanced burner geometry and combustion staging with control strategies tailored to mixtures of natural gas and byproduct fuel gases. These methods reduce all varieties of NOx – thermal NOx produced by high flame temperatures, prompt NOx produced by complex chain reactions involving radical hydrocarbon species and NOx from fuel-bound nitrogen compounds such as ammonia found in COG. The Project Team has expanded GTI’s highly successful low-NOx forced internal recirculation (FIR) burner, previously developed for natural gas-fired boilers, into facilities that utilize BFG and COG. For natural gas firing, these burners have been shown to reduce NOx emissions from typical uncontrolled levels of 80-100 vppm to single-digit levels (9 vppm). This is done without the energy efficiency penalties incurred by alternative NOx control methods, such as external flue gas recirculation (FGR), water injection, and
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Ceyer, Sylvia T.; Lahr, David L.
2010-11-09
The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.
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McDonald, Jacob D.; Harrod, Kevin S.; Seagrave, JeanClare; Seilkop, Steven K.; Mauderly, Joe L.
2004-01-01
In this study we compared a “baseline” condition of uncontrolled diesel engine exhaust (DEE) emissions generated with current (circa 2003) certification fuel to an emissions-reduction (ER) case with low sulfur fuel and a catalyzed particle trap. Lung toxicity assessments (resistance to respiratory viral infection, lung inflammation, and oxidative stress) were performed on mice (C57Bl/6) exposed by inhalation (6 hr/day for 7 days). The engine was operated identically (same engine load) in both cases, and the inhalation exposures were conducted at the same exhaust dilution rate. For baseline DEE, this dilution resulted in a particle mass (PM) concentration of approximately 200 μg/m3 PM, whereas the ER reduced the PM and almost every other measured constituent [except nitrogen oxides (NOx)] to near background levels in the exposure atmospheres. These measurements included PM, PM size distribution, PM composition (carbon, ions, elements), NOx, carbon monoxide, speciated/total volatile hydrocarbons, and several classes of semi-volatile organic compounds. After exposure concluded, one group of mice was immediately sacrificed and assessed for inflammation and oxidative stress in lung homogenate. Another group of mice were intratracheally instilled with respiratory syncytial virus (RSV), and RSV lung clearance and inflammation was assessed 4 days later. Baseline DEE produced statistically significant biological effects for all measured parameters. The use of low sulfur fuel and a catalyzed trap either completely or nearly eliminated the effects. PMID:15345344
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Explaining a Consistent Morning NOx Maximum in the Clean Air Forest Boundary Layer
NASA Astrophysics Data System (ADS)
Shepson, P. B.; Alaghmand, M.; Bertman, S. B.; Carroll, M.; Edburg, S. L.; Jobson, B. T.; Keutsch, F. N.; Lamb, B. K.; Starn, T.; Stevens, P. S.; Wallace, W.; Zhou, X.
2010-12-01
Measurements of nitrogen oxides (NOx) at continental surface sites have frequently revealed the presence of an early morning maximum in the NOx concentration. While this observation has most often been interpreted as the result of downward mixing associated with breakup of the nocturnal inversion, the morning NOx peak often occurs earlier than the NBL breakup. Given the importance of NOx to boundary layer photochemistry near forested environments, it is essential that this phenomenon be well understood. Here we examine a variety of measurements, including NOx measurements at various heights, during the 1998, 2001, 2008, and 2009 (CABINEX) summer intensives of the Program for Research on Oxidants: PHotochemistry, Emissions and Transport (PROPHET), at the University of Michigan Biological Station in Northern Michigan. We will discuss the results, in terms of the extent to which the observations support/refute each of the potential drivers of the morning NOx peak: 1) downward mixing, 2) photochemistry on the various surfaces present, 3) soil emissions, and 4) local and long range transport of anthropogenic NOx, and we will report on our conclusions as to the predominant/likely explanation(s) for this phenomenon.
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40 CFR 52.2308 - Area-wide nitrogen oxides (NOX) exemptions.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 5 2014-07-01 2014-07-01 false Area-wide nitrogen oxides (NOX) exemptions. 52.2308 Section 52.2308 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR...-wide nitrogen oxides (NOX) exemptions. (a) The Texas Natural Resource Conservation Commission (TNRCC...
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40 CFR 52.2308 - Area-wide nitrogen oxides (NOX) exemptions.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 5 2013-07-01 2013-07-01 false Area-wide nitrogen oxides (NOX) exemptions. 52.2308 Section 52.2308 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR...-wide nitrogen oxides (NOX) exemptions. (a) The Texas Natural Resource Conservation Commission (TNRCC...
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40 CFR 52.2308 - Area-wide nitrogen oxides (NOX) exemptions.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 5 2012-07-01 2012-07-01 false Area-wide nitrogen oxides (NOX) exemptions. 52.2308 Section 52.2308 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR...-wide nitrogen oxides (NOX) exemptions. (a) The Texas Natural Resource Conservation Commission (TNRCC...
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SOURCEBOOK: NOX CONTROL TECHNOLOGY DATA
The report, a compilation of available information on the control of nitrogen oxide (NOx) emissions from stationary sources, is provided to assist new source permitting activities by regulatory agencies. he sources covered are combustion turbines, internal combustion engines, non...
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CRISPR-Cas9 Mediated NOX4 Knockout Inhibits Cell Proliferation and Invasion in HeLa Cells.
Jafari, Naser; Kim, Hyunju; Park, Rackhyun; Li, Liqing; Jang, Minsu; Morris, Andrew J; Park, Junsoo; Huang, Cai
2017-01-01
Increased expression of NOX4 protein is associated with cancer progression and metastasis but the role of NOX4 in cell proliferation and invasion is not fully understood. We generated NOX4 knockout HeLa cell lines using the CRISPR-Cas9 gene editing system to explore the cellular functions of NOX4. After transfection of CRISPR-Cas9 construct, we performed T7 endonuclease 1 assays and DNA sequencing to generate and identify insertion and deletion of the NOX4 locus. We confirmed the knockout of NOX4 by Western blotting. NOX4 knockout cell lines showed reduced cell proliferation with an increase of sub-G1 cell population and the decrease of S/G2/M population. Moreover, NOX4 deficiency resulted in a dramatic decrease in invadopodium formation and the invasive activity. In addition, NOX4 deficiency also caused a decrease in focal adhesions and cell migration in HeLa cells. These results suggest that NOX4 is required for both efficient proliferation and invasion of HeLa cells.
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Textured catalysts and methods of making textured catalysts
Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA
2007-03-06
A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.
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Origin of tropospheric NO(x) over subarctic eastern Canada in summer
NASA Technical Reports Server (NTRS)
Fan, S.-M; Jacob, D. J.; Mauzerall, D. L.; Bradshaw, J. D.; Sandholm, S. T.; Blake, D. R.; Singh, H. B.; Talbot, R. W.; Gregory, G. L.; Sachse, G. W.
1994-01-01
The original of NO(X) in the summertime troposphere over subarctic eastern Canada is investigated by photochemical modeling of aircraft and ground-based measurements from the Arctic Boundary Layer Expedition (ABLE 3B). It is found that decomposition of peroxyacetyl nitrate (PAN) can account for most of the NO(X) observed between the surface and 6.2 km altitude (aircraft ceiling). Forest fires represent the principal source of PAN in the region, implying the same origin for NO(X). There is, however, evidence for an unidentified source of NO(X) in occasional air masses subsiding from the upper troposphere. Isoprene emissions from boreal forests maintain high NO(X) concentrations in the continental boundary layer over eastern Canada by scavenging OH and NO3, thus slowing down conversion of NO(X) to HNO3, both in the daytime and at night. This effect is partly compensated by the production of CH3CO3 radicals during isoprene oxidation, which slows down the decomposition of PAN subsiding from the free troposphere. The peroxy radical concentrations estimated from concurrent measurements of NO and NO2 concentrations during ABLE 3B are consistent with values computed from our photochemical model below 4 km, but model values are low at higher altitudes. The discrepancy may reflect either a missing radical source in the model or interferences in the NO2 measurement.
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The effect of functional forms of nitrogen on fuel-NOx emissions.
Zhang, Linghui; Su, Dagen; Zhong, Mingfeng
2015-01-01
This work explores the effects of different nitrogen functional forms on fuel-NOx emissions at 900 °C. The majority of tests are performed with an excess air coefficient of 1.4. Fuel-NOx is detected by measuring N-(1-naphthyl) ethylenediamine dihydrochloride (C₁₂H₁₆Cl₂N₂) via spectrophotometry. The different functional forms of nitrogen in the raw materials are identified by using X-ray photoelectron spectroscopy (XPS). A reliable density functional theory (DFT) method at the B3LYP/6-311++G** level is employed to investigate the reaction pathways of all functional forms of nitrogen during combustion. The results indicate that the functional forms of nitrogen influence the formation of nitrogen oxides. While under the same experimental conditions, fuel-NOx emissions increase by using less activation energy and nitrogen-containing groups with poor thermal stability. It is determined that fuel-NOx emissions vary in the following order: glycine > pyrrole > pyridine > methylenedi-p-phenylene diisocyanate (MDI). Glycine is the chain structure of amino acids in waste-leather and has low activation energy and poor thermal stability. With these properties, it is noted that glycine produces the most fuel-NOx in all of the raw materials studied. More pyrrole than pyridine in coal lead to high yields of fuel-NOx. The lowest yields of fuel-NO x are obtained using polyurethanes in waste-PU.
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Brandt, Moritz; Garlapati, Venkata; Oelze, Matthias; Sotiriou, Efthymios; Knorr, Maike; Kröller-Schön, Swenja; Kossmann, Sabine; Schönfelder, Tanja; Morawietz, Henning; Schulz, Eberhard; Schultheiss, Heinz-Peter; Daiber, Andreas; Münzel, Thomas; Wenzel, Philip
2016-01-01
Alcoholic cardiomyopathy (ACM) resulting from excess alcohol consumption is an important cause of heart failure (HF). Although it is assumed that the cardiotoxicity of the ethanol (EtOH)-metabolite acetaldehyde (ACA) is central for its development and progression, the exact mechanisms remain obscure. Murine cardiomyocytes (CMs) exposed to ACA or EtOH showed increased superoxide (O2•−) levels and decreased mitochondrial polarization, both being normalized by NADPH oxidase (NOX) inhibition. C57BL/6 mice and mice deficient for the ACA-degrading enzyme mitochondrial aldehyde dehydrogenase (ALDH-2−/−) were fed a 2% EtOH diet for 5 weeks creating an ACA-overload. 2% EtOH-fed ALDH-2−/− mice exhibited a decreased cardiac function, increased heart-to-body and lung-to-body weight ratios, increased cardiac levels of the lipid peroxidation product malondialdehyde (MDA) as well as increased NOX activity and NOX2/glycoprotein 91phox (NOX2/gp91phox) subunit expression compared to 2% EtOH-fed C57BL/6 mice. Echocardiography revealed that ALDH-2−/−/gp91phox−/− mice were protected from ACA-overload-induced HF after 5 weeks of 2% EtOH-diet, demonstrating that NOX2-derived O2•− contributes to the development of ACM. Translated to human pathophysiology, we found increased gp91phox expression in endomyocardial biopsies of ACM patients. In conclusion, ACM is promoted by ACA-driven mitochondrial dysfunction and can be improved by ablation of NOX2/gp91phox. NOX2/gp91phox therefore might be a potential pharmacological target to treat ACM. PMID:27624556
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Trap style influences wild pig behavior and trapping success
Williams, B.L.; Holtfreter, R.W.; Ditchkoff, S.S.; Grand, J.B.
2011-01-01
Despite the efforts of many natural resource professionals, wild pig (Sus scrofa) populations are expanding in many areas of the world. Although many creative techniques for controlling pig populations are being explored, trapping has been and still is themost commonly usedmethod of population control formany public and private land managers. We conducted an observational study to examine the efficiency of 2 frequently used trap styles: a small, portable box-style trap and a larger, semi-permanent, corral-style trap.We used game cameras to examine patterns of trap entry by wild pigs around each style of trap, and we conducted a trapping session to compare trapping success between trap styles. Adult female and juvenile wild pigs entered both styles of trap more readily than did adult males, and adult males seemed particularly averse to entering box traps. Less than 10% of adult male visits to box traps resulted in entries, easily the least percentage of any class at any style of trap. Adult females entered corral traps approximately 2.2 times more often per visit than box traps and re-entered corral traps >2 times more frequently. Juveniles entered and reentered both box and corral traps at similar rates. Overall (all-class) entry-per-visit rates at corral traps (0.71) were nearly double that of box traps (0.37). Subsequent trapping data supported these preliminary entry data; the capture rate for corral traps was >4 times that of box traps. Our data suggest that corral traps are temporally and economically superior to box traps with respect to efficiency; that is, corral traps effectively trap more pigs per trap night at a lower cost per pig than do box traps. ?? 2011 The Wildlife Society.
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40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for CAIR NOX Ozone... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting authority...
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40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX Ozone... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting authority...
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40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX Ozone... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting authority...
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40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for CAIR NOX Ozone... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting authority...
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40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for CAIR NOX Ozone... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting authority...
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40 CFR 52.2351 - Area-wide nitrogen oxides (NOX) exemption.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 5 2012-07-01 2012-07-01 false Area-wide nitrogen oxides (NOX) exemption. 52.2351 Section 52.2351 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... nitrogen oxides (NOX) exemption. On May 2, 1997, Ursula Trueman, Director, Division of Air Quality, Utah...
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40 CFR 52.2351 - Area-wide nitrogen oxides (NOX) exemption.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Area-wide nitrogen oxides (NOX) exemption. 52.2351 Section 52.2351 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... nitrogen oxides (NOX) exemption. On May 2, 1997, Ursula Trueman, Director, Division of Air Quality, Utah...
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40 CFR 52.2351 - Area-wide nitrogen oxides (NOX) exemption.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 5 2013-07-01 2013-07-01 false Area-wide nitrogen oxides (NOX) exemption. 52.2351 Section 52.2351 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... nitrogen oxides (NOX) exemption. On May 2, 1997, Ursula Trueman, Director, Division of Air Quality, Utah...
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40 CFR 52.2351 - Area-wide nitrogen oxides (NOX) exemption.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 5 2014-07-01 2014-07-01 false Area-wide nitrogen oxides (NOX) exemption. 52.2351 Section 52.2351 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... nitrogen oxides (NOX) exemption. On May 2, 1997, Ursula Trueman, Director, Division of Air Quality, Utah...
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40 CFR 52.2351 - Area-wide nitrogen oxides (NOX) exemption.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Area-wide nitrogen oxides (NOX) exemption. 52.2351 Section 52.2351 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... nitrogen oxides (NOX) exemption. On May 2, 1997, Ursula Trueman, Director, Division of Air Quality, Utah...
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40 CFR 96.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General CAIR NOX Ozone Season Trading... PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating...
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40 CFR 96.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General CAIR NOX Ozone Season Trading... PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating...
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40 CFR 96.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General CAIR NOX Ozone Season Trading... PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating...
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40 CFR 96.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General CAIR NOX Ozone Season Trading... PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating...
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40 CFR 96.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General CAIR NOX Ozone Season Trading... PROGRAMS FOR STATE IMPLEMENTATION PLANS Permits § 96.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating...
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The challenge to NOx emission control for heavy-duty diesel vehicles in China
NASA Astrophysics Data System (ADS)
Wu, Y.; Zhang, S. J.; Li, M. L.; Ge, Y. S.; Shu, J. W.; Zhou, Y.; Xu, Y. Y.; Hu, J. N.; Liu, H.; Fu, L. X.; He, K. B.; Hao, J. M.
2012-07-01
China's new "Twelfth Five-Year Plan" set a target for total NOx emission reduction of 10% for the period of 2011-2015. Heavy-duty diesel vehicles (HDDVs) have been considered a major contributor to NOx emissions in China. Beijing initiated a comprehensive vehicle test program in 2008. This program included a sub-task for measuring on-road emission profiles of hundreds of HDDVs using portable emission measurement systems (PEMS). The major finding is that neither the on-road distance-specific (g km -1) nor brake-specific (g kW h-1) NOx emission factors for diesel buses and heavy-duty diesel trucks improved in most cases as emission standards became more stringent. For example, the average NOx emission factors for Euro II, Euro III and Euro IV buses are 11.3±3.3 g km-1, 12.5± 1.3 g km-1, and 11.8±2.0 g km-1, respectively. No statistically significant difference in NOx emission factors was observed between Euro II and III buses. Even for Euro IV buses equipped with SCR systems, the NOx emission factors are similar to Euro III buses. The data regarding real-time engine performance of Euro IV buses suggest the engine certification cycles did not reflect their real-world operating conditions. These new on-road test results indicate that previous estimates of total NOx emissions for HDDV fleet may be significantly underestimated. The new estimate in total NOx emissions for the Beijing HDDV fleet in 2009 is 37.0 Gg, an increase of 45% compared to the previous study. Further, we estimate that the total NOx emissions for the national HDDV fleet in 2009 are approximately 4.0 Tg, higher by 1.0 Tg (equivalent to 18% of total NOx emissions for vehicle fleet in 2009) than that estimated in the official report. This would also result in 4% increase in estimation of national anthropogenic NOx emissions. More effective control measures (such as promotion of CNG buses and a new in-use compliance testing program) are urged to secure the goal of total NOxmitigation for the HDDV fleet
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Redox signaling, Nox5 and vascular remodeling in hypertension.
Montezano, Augusto C; Tsiropoulou, Sofia; Dulak-Lis, Maria; Harvey, Adam; Camargo, Livia De Lucca; Touyz, Rhian M
2015-09-01
Extensive data indicate a role for reactive oxygen species (ROS) and redox signaling in vascular damage in hypertension. However, molecular mechanisms underlying these processes remain unclear, but oxidative post-translational modification of vascular proteins is critical. This review discusses how proteins are oxidatively modified and how redox signaling influences vascular smooth muscle cell growth and vascular remodeling in hypertension. We also highlight Nox5 as a novel vascular ROS-generating oxidase. Oxidative stress in hypertension leads to oxidative imbalance that affects vascular cell function through redox signaling. Many Nox isoforms produce ROS in the vascular wall, and recent findings show that Nox5 may be important in humans. ROS regulate signaling by numerous processes including cysteine oxidative post-translational modification such as S-nitrosylation, S-glutathionylation and sulfydration. In vascular smooth muscle cells, this influences cellular responses to oxidative stimuli promoting changes from a contractile to a proliferative phenotype. In hypertension, Nox-induced ROS production is increased, leading to perturbed redox signaling through oxidative modifications of vascular proteins. This influences mitogenic signaling and cell cycle regulation, leading to altered cell growth and vascular remodeling in hypertension.
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Burgard, Daniel A; Provinsal, Melissa N
2009-12-01
A remote sensing device was used to obtain on-road and in-use gaseous emission measurements from three fleets of schools buses at two locations in Washington State. This paper reports each fleet's carbon monoxide (CO), hydrocarbon (HC), nitric oxide (NO), and nitrogen dioxide (NO2) mean data. The fleets represent current emission retrofit technologies, such as diesel particulate filters and diesel oxidation catalysts, and a control fleet. This study shows that CO and HC emissions decrease with the use of either retrofit technology when compared with control buses of the same initial emission standards. The CO and HC emission reductions are consistent with published U.S. Environmental Protection Agency verified values. The total oxides of nitrogen (NOx), NO, and the NO2/NOx ratio all increase with each retrofit technology when compared with control buses. As was expected, the diesel particulate filters emitted significantly higher levels of NO2 than the control fleet because of the intentional conversion of NO to NO2 by these systems. Most prior research suggests that NOx emissions are unaffected by the retrofits; however, these previous studies have not included measurements from retrofit devices on-road and after nearly 5 yr of use. Two 2006 model-year buses were also measured. These vehicles did not have retrofit devices but were built to more stringent new engine standards. Reductions in HCs and NOx were observed for these 2006 vehicles in comparison to other non-retrofit earlier model-year vehicles.
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The impact on the ozone layer from NOx produced by terrestrial gamma ray flashes
NASA Astrophysics Data System (ADS)
Cramer, E. S.; Briggs, M. S.; Liu, N.; Mailyan, B.; Dwyer, J. R.; Rassoul, H. K.
2017-05-01
The motivation of this work is to understand the effects of terrestrial gamma ray flashes (TGFs) on the ozone layer. One of the main ozone-destroying mechanisms is the production of NOx in the stratospheric region. NOx from lightning has been considered as a possible cause of ozone depletion, but probably little of this NOx is transported from the tropopause to the stratosphere. Since the energetic particles of TGFs travel from ≈12 km to space, the resulting ionization can produce NOx directly in the stratosphere. In order to quantify the production of stratospheric NOx from TGFs, we use the Runaway Electron Avalanche Model to simulate a typical setup of the acceleration region inside a thundercloud. The photons are then transported through the Earth's atmosphere, where they deposit some of their energy as ionization in the ozone layer. We then calculate the number of NOx molecules produced by considering the average energy required to produce one electron-ion pair. Finally, the effect of TGF NOx production is estimated using the global annual rate of TGFs. It is estimated that the NOx production of TGFs is completely negligible compared to other sources, and therefore, TGFs have no effect on the ozone layer.
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Nrf2 mediates redox adaptation in NOX4-overexpressed non-small cell lung cancer cells
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wu, Qipeng; Yao, Bei; Li, Ning
The redox adaptation mechanisms in cancer cells are very complex and remain largely unclear. Our previous studies have confirmed that NADPH oxidase 4 (NOX4) is abundantly expressed in non-small cell lung cancer (NSCLC) and confers apoptosis resistance on NSCLC cells. However, the comprehensive mechanisms for NOX4-mediated oxidative resistance of cancer cells remain still undentified. The present study found that NOX4-derived H{sub 2}O{sub 2} enhanced the nuclear factor erythroid 2-related factor 2 (Nrf2) stability via disruption of redox-dependent proteasomal degradation and stimulated its activity through activation of PI3K signaling. Specifically, the results showed that ectopic NOX4 expression did not induce apoptosismore » of A549 cells; however, inhibition of Nrf2 resulted in obvious apoptotic death of NOX4-overexpressed A549 cells, accompanied by a significant increase in H{sub 2}O{sub 2} level and decrease in GSH content. Besides, inhibition of Nrf2 could suppress cell growth and efficiently reverse the enhancement effect of NOX4 on cell growth. The in vivo data confirmed that inhibition of Nrf2 could interfere apoptosis resistance in NOX4-overexpressed A549 tumors and led to cell growth inhibition. In conclusion, these results reveal that Nrf2 is critically involved in redox adaptation regulation in NOX4-overexpressed NSCLC cells. Therefore, NOX4 and Nrf2 may be promising combination targets against malignant progression of NSCLC. - Highlights: • NOX4-derived H{sub 2}O{sub 2} upregulates Nrf2 expression and activity in NSCLC. • Nrf2 confers apoptosis resistance in NOX4-overexpressed NSCLC cells. • Inhibition of Nrf2 reverses the enhancement effect of NOX4 on cell growth.« less
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Selectivity of Vibrio cholerae H-NOX for Gaseous Ligands Follows “Sliding Scale Rule” Hypothesis
Wu, Gang; Liu, Wen; Berka, Vladimir; Tsai, Ah-lim
2014-01-01
Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 μM, respectively, but weakly to O2. When positioned in “sliding scale” plot {Tsai, A.-L. et. al. (2012) Biochemistry, 51, pp172-86}, the line connecting logKD(NO) and logKD(CO) of Vc H-NOX is almost superimposable with that of Ns H-NOX. Therefore, the measured affinities and kinetic parameters of gaseous ligands to Vc H-NOX provide more evidence to validate the “sliding scale rule” hypothesis. Like sGC, Vc H-NOX binds NO in multiple steps, forming first a 6-coordinate heme-NO complex with a rate of 1.1 × 109 M−1s−1, and then converts to a 5c heme-NO complex at a rate also dependent on [NO]. Although the formation of oxyferrous Vc H-NOX is not detectable under normal atmospheric oxygen level, ferrous Vc H-NOX is oxidized to ferric form at a rate of 0.06 s−1 when mixed with O2. Ferric Vc H-NOX exists as a mixture of high- and low-spin states and is influenced by binding to different ligands. Characterization of both ferric and ferrous Vc H-NOX and their complexes with various ligands lay the foundation for understanding the possible dual roles in gas and redox sensing of Vc H-NOX. PMID:24351060
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40 CFR 97.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 22 2013-07-01 2013-07-01 false General CAIR NOX Ozone Season Trading... TRADING PROGRAMS Permits § 97.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating permit or required, under...
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40 CFR 97.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 21 2014-07-01 2014-07-01 false General CAIR NOX Ozone Season Trading... TRADING PROGRAMS Permits § 97.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating permit or required, under...
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40 CFR 97.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 21 2011-07-01 2011-07-01 false General CAIR NOX Ozone Season Trading... TRADING PROGRAMS Permits § 97.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating permit or required, under...
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40 CFR 97.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 22 2012-07-01 2012-07-01 false General CAIR NOX Ozone Season Trading... TRADING PROGRAMS Permits § 97.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating permit or required, under...
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40 CFR 97.320 - General CAIR NOX Ozone Season Trading Program permit requirements.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false General CAIR NOX Ozone Season Trading... TRADING PROGRAMS Permits § 97.320 General CAIR NOX Ozone Season Trading Program permit requirements. (a) For each CAIR NOX Ozone Season source required to have a title V operating permit or required, under...
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Not Available
1994-03-01
Industrial, commercial, and institutional (ICI) boilers have been identified as a category that emits more than 25 tons of oxides of nitrogen (NOx) per year. This alternative control techniques (ACT) document provides technical information for use by State and local agencies to develop and implement regulatory programs to control NOx emissions from ICI boilers. Additional ACT documents are being developed for other stationary source categories. Chapter 2 summarizes the findings of this study. Chapter 3 presents information on the ICI boiler types, fuels, operation, and industry applications. Chapter 4 discusses NOx formation and uncontrolled NOx emission factors. Chapter 5 coversmore » alternative control techniques and achievable controlled emission levels. Chapter 6 presents the cost and cost effectiveness of each control technique. Chapter 7 describes environmental and energy impacts associated with implementing the NOx control techniques. Finally, Appendices A through G provide the detailed data used in this study to evaluate uncontrolled and controlled emissions and the costs of controls for several retrofit scenarios.« less
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Estimating Lightning NOx Emissions for Regional Air Quality Modeling
NASA Astrophysics Data System (ADS)
Holloway, T.; Scotty, E.; Harkey, M.
2014-12-01
Lightning emissions have long been recognized as an important source of nitrogen oxides (NOx) on a global scale, and an essential emission component for global atmospheric chemistry models. However, only in recent years have regional air quality models incorporated lightning NOx emissions into simulations. The growth in regional modeling of lightning emissions has been driven in part by comparisons with satellite-derived estimates of column NO2, especially from the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. We present and evaluate a lightning inventory for the EPA Community Multiscale Air Quality (CMAQ) model. Our approach follows Koo et al. [2010] in the approach to spatially and temporally allocating a given total value based on cloud-top height and convective precipitation. However, we consider alternate total NOx emission values (which translate into alternate lightning emission factors) based on a review of the literature and performance evaluation against OMI NO2 for July 2007 conditions over the U.S. and parts of Canada and Mexico. The vertical distribution of lightning emissions follow a bimodal distribution from Allen et al. [2012] calculated over 27 vertical model layers. Total lightning NO emissions for July 2007 show the highest above-land emissions in Florida, southeastern Texas and southern Louisiana. Although agreement with OMI NO2 across the domain varied significantly depending on lightning NOx assumptions, agreement among the simulations at ground-based NO2 monitors from the EPA Air Quality System database showed no meaningful sensitivity to lightning NOx. Emissions are compared with prior studies, which find similar distribution patterns, but a wide range of calculated magnitudes.
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NOx formation in combustion of gaseous fuel in ejection burner
NASA Astrophysics Data System (ADS)
Rimár, Miroslav; Kulikov, Andrii
2016-06-01
The aim of this work is to prepare model for researching of the formation in combustion of gaseous fuels. NOx formation is one of the main ecological problems nowadays as nitrogen oxides is one of main reasons of acid rains. The ANSYS model was designed according to the calculation to provide full combustion and good mixing of the fuel and air. The current model is appropriate to research NOx formation and the influence of the different principles of NOx reduction method. Applying of designed model should spare both time of calculations and research and also money as you do not need to measure the burner characteristics.
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Production of NOx by Lightning and its Effects on Atmospheric Chemistry
NASA Technical Reports Server (NTRS)
Pickering, Kenneth E.
2009-01-01
Production of NO(x) by lightning remains the NO(x) source with the greatest uncertainty. Current estimates of the global source strength range over a factor of four (from 2 to 8 TgN/year). Ongoing efforts to reduce this uncertainty through field programs, cloud-resolved modeling, global modeling, and satellite data analysis will be described in this seminar. Representation of the lightning source in global or regional chemical transport models requires three types of information: the distribution of lightning flashes as a function of time and space, the production of NO(x) per flash, and the effective vertical distribution of the lightning-injected NO(x). Methods of specifying these items in a model will be discussed. For example, the current method of specifying flash rates in NASA's Global Modeling Initiative (GMI) chemical transport model will be discussed, as well as work underway in developing algorithms for use in the regional models CMAQ and WRF-Chem. A number of methods have been employed to estimate either production per lightning flash or the production per unit flash length. Such estimates derived from cloud-resolved chemistry simulations and from satellite NO2 retrievals will be presented as well as the methodologies employed. Cloud-resolved model output has also been used in developing vertical profiles of lightning NO(x) for use in global models. Effects of lightning NO(x) on O3 and HO(x) distributions will be illustrated regionally and globally.
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Designing, installing and operating low NOx combustion systems in power plants
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lazzeri, L.; Santis, R. de
1997-09-01
Ansaldo Energia, in strict cooperation with the Italian Electricity Board (ENEL), has developed and implemented innovative technologies for in furnace NOx control which have been applied, both in italy and abroad, on over 20,000 MWe boilers of every kind (Tangentially Fired, Front Fired, Opposite Fired) and for different fuels like oil, gas, coal and ORIMULSION{reg_sign}. Taking advantage of innovative low NOx burners and of optimized air and fuel staging techniques NOx reductions up to 85% have been obtained with no significant impact on boiler efficiency. The paper describes: characteristics and industrial application of TEA{reg_sign} oil/gas LNB which is now capablemore » of attaining NOx reductions up to 60% in respect to original circular burners; development and industrial applications of the TEA C{reg_sign} (oil/coal) LNB, capable of attaining NOx reductions up to 50% with contemporary control of unburned carbon levels (typical values less than 300 ppm NOx corrected to 6% O{sub 2} and less than 7% UBC); application of reburning oil over oil and gas over oil for both tangential and front-opposite fired boilers rated up 660 MWe; and information on the CEE THERMIE projects of gas over coal reburning in a 600 MWe Scottish Power boiler and oil over coal and coal over coal reburning in the ENEL plant of Vado Ligure unit 4, rated 320 MWe.« less
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McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Saunders, Timothy P; Schmuttenmaer, Charles A; Mallouk, Thomas E
2016-07-06
Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize a sensitized metal oxide and a water oxidation catalyst in order to generate hydrogen and oxygen from water. Although the Faradaic efficiency of water splitting is close to unity, the recombination of photogenerated electrons with oxidized dye molecules causes the quantum efficiency of these devices to be low. It is therefore important to understand recombination mechanisms in order to develop strategies to minimize them. In this paper, we discuss the role of proton intercalation in the formation of recombination centers. Proton intercalation forms nonmobile surface trap states that persist on time scales that are orders of magnitude longer than the electron lifetime in TiO2. As a result of electron trapping, recombination with surface-bound oxidized dye molecules occurs. We report a method for effectively removing the surface trap states by mildly heating the electrodes under vacuum, which appears to primarily improve the injection kinetics without affecting bulk trapping dynamics, further stressing the importance of proton control in WS-DSPECs.
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N+2 Advanced Low NOx Combustor Technology Final Report
NASA Technical Reports Server (NTRS)
Herbon, John; Aicholtz, John; Hsieh, Shih-Yang; Viars, Philip; Birmaher, Shai; Brown, Dan; Patel, Nayan; Carper, Doug; Cooper, Clay; Fitzgerald, Russell
2017-01-01
In accordance with NASAs technology goals for future subsonic vehicles, this contract identified and developed new combustor concepts toward meeting N+2 generation (2020) LTO (landing and take-off) NOx emissions reduction goal of 75 from the standard adopted at Committee on Aviation Environmental Protection 6 (CAEP6). Based on flame tube emissions, operability, and autoignition testing, one concept was down selected for sector testing at NASA. The N+2 combustor sector successfully demonstrated 75 reduction for LTO NOx (vs. CAEP6) and cruise NOx (vs. 2005 B777-200 reference) while maintaining 99.9 cruise efficiency and no increase in CO and HC emissions.The program also developed enabling technologies for the combustion system including ceramic matrix composites (CMC) liner materials, active combustion control concepts, and laser ignition for improved altitude relight.
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He, Chao; Li, Jiaqiang; Ma, Zhilei; Tan, Jianwei; Zhao, Longqing
2015-09-01
Diesel vehicles are responsible for most of the traffic-related nitrogen oxide (NOx) emissions, including nitric oxide (NO) and nitrogen dioxide (NO2). The use of after-treatment devices increases the risk of high NO2/NOx emissions from diesel engines. In order to investigate the factors influencing NO2/NOx emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter (CDPF). NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NOx ratios downstream of the CDPF range around 20%-83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NOx emissions. The maximum NO2/NOx emission appears at the exhaust temperature of 350°C. The space velocity, engine-out PM/NOx ratio (mass based) and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NOx emissions decreased with increasing space velocity and engine-out PM/NOx ratio. When the CO conversion ratios range from 80% to 90%, the NO2/NOx emissions remain at a high level. Copyright © 2015. Published by Elsevier B.V.
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Brun, Sylvain; Malagnac, Fabienne; Bidard, Frédérique; Lalucque, Hervé; Silar, Philippe
2009-10-01
NADPH oxidases are enzymes that produce reactive oxygen species. Studies in mammals, plants and fungi have shown that they play important roles in differentiation, defence, host/pathogen interaction and mutualistic symbiosis. In this paper, we have identified a Podospora anserina mutant strain impaired for processes controlled by PaNox1 and PaNox2, the two Nox isoforms characterized in this model ascomycete. We show that the gene mutated is PaNoxR, the homologue of the gene encoding the regulatory subunit p67(phox), conserved in mammals and fungi, and that PaNoxR regulates both PaNox1 and PaNox2. Genome sequence analysis of P. anserina reveals that this fungus posses a third Nox isoform, PaNox3, related to human Nox5/Duox and plant Rboh. We have generated a knock-out mutant of PaNox3 and report that PaNox3 plays a minor role in P. anserina, if any. We show that PaNox1 and PaNox2 play antagonist roles in cellulose degradation. Finally, we report for the first time that a saprobic fungus, P. anserina, develops special cell structures dedicated to breach and to exploit a solid cellulosic substrate, cellophane. Importantly, as for similar structures present in some plant pathogens, their proper differentiation requires PaNox1, PaNox2, PaNoxR and the tetraspanin PaPls1.
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Pitts, J Roland [Lakewood, CO; Liu, Ping [Irvine, CA; Smith, R Davis [Golden, CO
2009-07-14
Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.
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Effects of temperature-dependent NOx emissions on continental ozone production
NASA Astrophysics Data System (ADS)
Romer, Paul S.; Duffey, Kaitlin C.; Wooldridge, Paul J.; Edgerton, Eric; Baumann, Karsten; Feiner, Philip A.; Miller, David O.; Brune, William H.; Koss, Abigail R.; de Gouw, Joost A.; Misztal, Pawel K.; Goldstein, Allen H.; Cohen, Ronald C.
2018-02-01
Surface ozone concentrations are observed to increase with rising temperatures, but the mechanisms responsible for this effect in rural and remote continental regions remain uncertain. Better understanding of the effects of temperature on ozone is crucial to understanding global air quality and how it may be affected by climate change. We combine measurements from a focused ground campaign in summer 2013 with a long-term record from a forested site in the rural southeastern United States, to examine how daily average temperature affects ozone production. We find that changes to local chemistry are key drivers of increased ozone concentrations on hotter days, with integrated daily ozone production increasing by 2.3 ppb °C-1. Nearly half of this increase is attributable to temperature-driven increases in emissions of nitrogen oxides (NOx), most likely by soil microbes. The increase of soil NOx emissions with temperature suggests that ozone will continue to increase with temperature in the future, even as direct anthropogenic NOx emissions decrease dramatically. The links between temperature, soil NOx, and ozone form a positive climate feedback.
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Prediction of the production of nitrogen oxide (NOx) in turbojet engines
NASA Astrophysics Data System (ADS)
Tsague, Louis; Tsogo, Joseph; Tatietse, Thomas Tamo
Gaseous nitrogen oxides (NO+NO2=NOx) are known as atmospheric trace constituent. These gases remain a big concern despite the advances in low NOx emission technology because they play a critical role in regulating the oxidization capacity of the atmosphere according to Crutzen [1995. My life with O 3, NO x and other YZO x S; Nobel Lecture; Chemistry 1995; pp 195; December 8, 1995] . Aircraft emissions of nitrogen oxides ( NOx) are regulated by the International Civil Aviation Organization. The prediction of NOx emission in turbojet engines by combining combustion operational data produced information showing correlation between the analytical and empirical results. There is close similarity between the calculated emission index and experimental data. The correlation shows improved accuracy when the 2124 experimental data from 11 gas turbine engines are evaluated than a previous semi empirical correlation approach proposed by Pearce et al. [1993. The prediction of thermal NOx in gas turbine exhausts. Eleventh International Symposium on Air Breathing Engines, Tokyo, 1993, pp. 6-9]. The new method we propose predict the production of NOx with far more improved accuracy than previous methods. Since a turbojet engine works in an atmosphere where temperature, pressure and humidity change frequently, a correction factor is developed with standard atmospheric laws and some correlations taken from scientific literature [Swartwelder, M., 2000. Aerospace engineering 410 Term Project performance analysis, November 17, 2000, pp. 2-5; Reed, J.A. Java Gas Turbine Simulator Documentation. pp. 4-5]. The new correction factor is validated with experimental observations from 19 turbojet engines cruising at altitudes of 9 and 13 km given in the ICAO repertory [Middleton, D., 1992. Appendix K (FAA/SETA). Section 1: Boeing Method Two Indices, 1992, pp. 2-3]. This correction factor will enable the prediction of cruise NOx emissions of turbojet engines at cruising speeds. The ICAO
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Volatile Release From The Siberian Traps Inferred From Melt Inclusions
NASA Astrophysics Data System (ADS)
Black, Benjamin A.; Elkins-Tanton, Linda T.; Rowe, Michael C.; Ukstins Peate, Ingrid
2010-05-01
concentrations in the range of one weight percent. Visscher et al. (2004) proposed that chlorofluorocarbon compounds (CFCs) may have played a major role in the terrestrial end-Permian extinction. These CFCs are powerful catalysts for the breakdown of ozone, a process which can expose the biosphere to increased ultraviolet radiation. Measurements of elevated chlorine and fluorine from the Siberian Traps may thus provide a concrete source for CFCs that could have triggered this kill mechanism.
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NASA Glenn High Pressure Low NOx Emissions Research
NASA Technical Reports Server (NTRS)
Tacina, Kathleen M.; Wey, Changlie
2008-01-01
In collaboration with U.S. aircraft engine companies, NASA Glenn Research Center has contributed to the advancement of low emissions combustion systems. For the High Speed Research Program (HSR), a 90% reduction in nitrogen oxides (NOx) emissions (relative to the then-current state of the art) has been demonstrated in sector rig testing at General Electric Aircraft Engines (GEAE). For the Advanced Subsonic Technology Program (AST), a 50% reduction in NOx emissions relative to the 1996 International Civil Aviation Organization (ICAO) standards has been demonstrated in sector rigs at both GEAE and Pratt & Whitney (P&W). During the Ultra Efficient Engine Technology Program (UEET), a 70% reduction in NOx emissions, relative to the 1996 ICAO standards, was achieved in sector rig testing at Glenn in the world class Advanced Subsonic Combustion Rig (ASCR) and at contractor facilities. Low NOx combustor development continues under the Fundamental Aeronautics Program. To achieve these reductions, experimental and analytical research has been conducted to advance the understanding of emissions formation in combustion processes. Lean direct injection (LDI) concept development uses advanced laser-based non-intrusive diagnostics and analytical work to complement the emissions measurements and to provide guidance for concept improvement. This paper describes emissions results from flametube tests of a 9-injection-point LDI fuel/air mixer tested at inlet pressures up to 5500 kPa. Sample results from CFD and laser diagnostics are also discussed.
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Catalytic oxidation of Hg(0) by MnOx-CeO2/γ-Al2O3 catalyst at low temperatures.
Wang, Pengying; Su, Sheng; Xiang, Jun; You, Huawei; Cao, Fan; Sun, Lushi; Hu, Song; Zhang, Yun
2014-04-01
MnOx-CeO2/γ-Al2O3 (MnCe) selective catalytic reduction (SCR) catalysts prepared by sol-gel method were employed for low-temperature Hg(0) oxidation on a fixed-bed experimental setup. BET, XRD and XPS were used to characterize the catalysts. MnCe catalysts exhibited high Hg(0) oxidation activity at low temperatures (100-250 °C) under the simulated flue gas (O2, CO2, NO, SO2, HCl, H2O and balanced with N2). Only a small decrease in mercury oxidation was observed in the presence of 1200 ppm SO2, which proved that the addition of Ce helped resist SO2 poisoning. An enhancing effect of NO was observed due to the formation of multi-activity NOx species. The presence of HCl alone had excellent Hg(0) oxidation ability, while 10 ppm HCl plus 5% O2 further increased Hg(0) oxidation efficiency to 100%. Hg(0) oxidation on the MnCe catalyst surface followed the Langmiur-Hinshelwood mechanism, where reactions took place between the adsorbed active species and adsorbed Hg(0) to form Hg(2+). NH3 competed with Hg(0) for active sites on the catalyst surface, hence inhibiting Hg(0) oxidation. This study shows the feasibility of a single-step process integrating low-temperature SCR and Hg(0) oxidation from the coal combustion flue gas. Copyright © 2013 Elsevier Ltd. All rights reserved.
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STAT5A-mediated NOX5-L expression promotes the proliferation and metastasis of breast cancer cells
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dho, So Hee; Radioisotope Research Division, Department of Research Reactor Utilization, Korea Atomic Energy Research Institute, Daejeon 305-353; Kim, Ji Young
NADPH oxidase (NOX) generates reactive oxygen species (ROS) and has been suggested to mediate cell proliferation in some cancers. Here, we show that an increase in the expression of NOX5 long form (NOX5-L) is critical for tumor progression in breast tumor tissues. Immunostaining of clinical samples indicated that NOX5 was overexpressed in 41.1% of breast ductal carcinoma samples. NOX5-L depletion consistently suppressed cell proliferation, invasion, and migration in vitro. Antibody-mediated neutralization of NOX5-L attenuated tumor progression in a mouse xenograft model. Promoter analysis revealed that NOX5-L expression is regulated by STAT5A in breast cancer cells. Based on our novel findings,more » we suggest that inhibition of NOX5-L may be a promising therapeutic strategy that exerts anti-cancer effects via the modulation of ROS-mediated cell signaling. - Highlights: • The ROS-generating protein, NOX5-L, determines cellular proliferation and metastasis in subset of breast tumor. • Tumor growth was attenuated by the treatment of anti-NOX5-L antibody in a xenograft model. • NOX5-L expression is transcriptionally regulated by STAT5A in breast cancer cells.« less
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Low NOx, Lean Direct Wall Injection Combustor Concept Developed
NASA Technical Reports Server (NTRS)
Tacina, Robert R.; Wey, Changlie; Choi, Kyung J.
2003-01-01
The low-emissions combustor development at the NASA Glenn Research Center is directed toward advanced high-pressure aircraft gas turbine applications. The emphasis of this research is to reduce nitrogen oxides (NOx) at high-power conditions and to maintain carbon monoxide and unburned hydrocarbons at their current low levels at low-power conditions. Low-NOx combustors can be classified into rich burn and lean burn concepts. Lean burn combustors can be further classified into lean-premixed-prevaporized (LPP) and lean direct injection (LDI) combustors. In both concepts, all the combustor air, except for liner cooling flow, enters through the combustor dome so that the combustion occurs at the lowest possible flame temperature. The LPP concept has been shown to have the lowest NOx emissions, but for advanced high-pressure-ratio engines, the possibly of autoignition or flashback precludes its use. LDI differs from LPP in that the fuel is injected directly into the flame zone and, thus, does not have the potential for autoignition or flashback and should have greater stability. However, since it is not premixed and prevaporized, the key is good atomization and mixing of the fuel quickly and uniformly so that flame temperatures are low and NOx formation levels are comparable to those of LPP.
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Murphy-Marshman, Hannah; Quensel, Katherine; Shi-wen, Xu; Barnfield, Rebecca; Kelly, Jacalyn; Peidl, Alex; Stratton, Richard J.
2017-01-01
TGFbeta induces fibrogenic responses in fibroblasts. Reactive oxygen species (ROS)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) may contribute to fibrogenic responses. Here, we examine if the antioxidant N-acetylcysteine (NAC), the NOX inhibitor diphenyleneiodonium (DPI) and the selective NOX1/NOX4 inhibitor GKT-137831 impairs the ability of TGFbeta to induce profibrotic gene expression in human gingival (HGF) and dermal (HDF) fibroblasts. We also assess if GKT-137831 can block the persistent fibrotic phenotype of lesional scleroderma (SSc) fibroblasts. We use real-time polymerase chain reaction and Western blot analysis to evaluate whether NAC and DPI impair the ability of TGFbeta1 to induce expression of fibrogenic genes in fibroblasts. The effects of GKT-137831 on TGFbeta-induced protein expression and the persistent fibrotic phenotype of lesional scleroderma (SSc) fibroblasts were tested using Western blot and collagen gel contraction analyses. In HDF and HGF, TGFbeta1 induces CCN2, CCN1, endothelin-1 and alpha-smooth muscle actin (SMA) in a fashion sensitive to NAC. Induction of COL1A1 mRNA was unaffected. Similar results were seen with DPI. NAC and DPI impaired the ability of TGFbeta1 to induce protein expression of CCN2 and alpha-SMA in HDF and HGF. GKT-137831 impaired TGFbeta-induced CCN2 and alpha-SMA protein expression in HGF and HDF. In lesional SSc dermal fibroblasts, GKT-137831 reduced alpha-SMA and CCN2 protein overexpression and collagen gel contraction. These results are consistent with the hypothesis that antioxidants or NOX1/4 inhibition may be useful in blocking profibrotic effects of TGFbeta on dermal and gingival fibroblasts and warrant consideration for further development as potential antifibrotic agents. PMID:29049376
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NOx Emissions from Diesel Passenger Cars Worsen with Age.
Chen, Yuche; Borken-Kleefeld, Jens
2016-04-05
Commonly, the NOx emissions rates of diesel vehicles have been assumed to remain stable over the vehicle's lifetime. However, there have been hardly any representative long-term emission measurements. Here we present real-driving emissions of diesel cars and light commercial vehicles sampled on-road over 15 years in Zurich/Switzerland. Results suggest deterioration of NOx unit emissions for Euro 2 and Euro 3 diesel technologies, while Euro 1 and Euro 4 technologies seem to be stable. We can exclude a significant influence of high-emitting vehicles. NOx emissions from all cars and light commercial vehicles in European emission inventories increase by 5-10% accounting for the observed deterioration, depending on the country and its share of diesel cars. We suggest monitoring the stability of emission controls particularly for high-mileage light commercial as well as heavy-duty vehicles.
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Measurement of Trap Length for an Optical Trap
NASA Technical Reports Server (NTRS)
Wrbanek, Susan Y.
2009-01-01
The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.
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Sensitivities of NOx transformation and the effects on surface ozone and nitrate
NASA Astrophysics Data System (ADS)
Lei, H.; Wang, J. X. L.
2013-08-01
As precursors for tropospheric ozone and nitrate aerosols, Nitrogen oxides (NOx) in present atmosphere and its transformation in responding to emission and climate perturbations are studied by CAM-Chem model and air quality measurements including National Emission Inventory (NEI), Clean Air Status and Trends Network (CASTNET) and Environmental Protection Agency Air Quality System (EPA AQS). It is found that not only the surface ozone formation but also the nitrate formation is associated with the relative emissions of NOx and volatile organic compounds (VOC). Due to the availability of VOC and associated NOx titration, ozone productions in industrial regions increase in warmer conditions and slightly decrease against NOx emission increase, which is converse to the response in farming region. The decrease or small increase in ozone concentrations over industrial regions result in the responded nitrate increasing rate staying above the increasing rate of NOx emissions. It is indicated that ozone concentration change is more directly affected by changes in climate and precursor emissions, while nitrate concentration change is also affected by local ozone production types and their seasonal transfer. The sensitivity to temperature perturbations shows that warmer climate accelerates the decomposition of odd nitrogen (NOy) during the night. As a result, the transformation rate of NOx to nitrate decreases. Examinations on the historical emission and air quality records on typical pollution areas further confirm the conclusion drawn from modeling experiments.
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Xiang, Fu-Li; Lu, Xiangru; Strutt, Brenda; Hill, David J.; Feng, Qingping
2010-01-01
OBJECTIVE The role of NOX2-containing NADPH oxidase in the development of diabetes is not fully understood. We hypothesized that NOX2 deficiency decreases reactive oxygen species (ROS) production and immune response and protects against streptozotocin (STZ)-induced β-cell destruction and development of diabetes in mice. RESEARCH DESIGN AND METHODS Five groups of mice—wild-type (WT), NOX2−/−, WT treated with apocynin, and WT adoptively transferred with NOX2−/− or WT splenocytes—were treated with multiple-low-dose STZ. Blood glucose and insulin levels were monitored, and an intraperitoneal glucose tolerance test was performed. Isolated WT and NOX2−/− pancreatic islets were treated with cytokines for 48 h. RESULTS Significantly lower blood glucose levels, higher insulin levels, and better glucose tolerance was observed in NOX2−/− mice and in WT mice adoptively transferred with NOX2−/− splenocytes compared with the respective control groups after STZ treatment. Compared with WT, β-cell apoptosis, as determined by TUNEL staining, and insulitis were significantly decreased, whereas β-cell mass was significantly increased in NOX2−/− mice. In response to cytokine stimulation, ROS production was significantly decreased, and insulin secretion was preserved in NOX2−/− compared with WT islets. Furthermore, proinflammatory cytokine release induced by concanavalin A was significantly decreased in NOX2−/− compared with WT splenocytes. CONCLUSIONS NOX2 deficiency decreases β-cell destruction and preserves islet function in STZ-induced diabetes by reducing ROS production, immune response, and β-cell apoptosis. PMID:20627937
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Pandey, Deepesh; Patel, Anand; Patel, Vijay; Chen, Feng; Qian, Jin; Wang, Yusi; Barman, Scott A.; Venema, Richard C.; Stepp, David W.; Daniel Rudic, R.
2012-01-01
The expression and functional significance of NADPH oxidase 5 (Nox5) and its five isoforms in vascular cells is poorly understood. The goal of this study was to determine whether Nox5-α, -β, -δ, -γ, and -ε (short) are expressed in human blood vessels and evaluate their respective functions. Nox5 mRNA and protein were detected in human blood vessels, cultured human vascular smooth muscle (HVSMC) and endothelium, but not fibroblasts. The most abundant isoforms were α and β, whereas δ and γ were not detected. Nox5-α and -β produced reactive oxygen species (ROS), but -δ, -γ, and -ε were not catalytically active. Coexpression of the active Nox5 isoforms with inactive Nox5 variants suppressed ROS production, and coimmunoprecipitation revealed that Nox5-β binds the inactive ε variant, which may account for reduced ROS production. In HVSMC, angiotensin II, endothelin-1 and TNF-α increased endogenous Nox5 mRNA levels, while adenovirus-mediated overexpression of Nox5 promoted p38 MAPK, JAK2, JNK, and ERK1/2 phosphorylation in endothelial cells (EC), but only increased ERK1/2 phosphorylation in HVSMC. At higher levels of Nox5, there was evidence of increased apoptosis in EC, but not in HVSMC, as detected by the presence of cleaved caspase-3 and cleaved poly(ADP-ribose)polymerase. Although catalytically inactive, Nox5-ε potently activated ERK in HVSMC, and increased expression of Nox5-ε promoted HVSMC proliferation. Nox5 is expressed in human blood vessels. The Nox5-α and -β splice variants are the major isoforms that are expressed and the only variants capable of ROS production. Nox5-ε can inhibit Nox5 activity and activate ERK and HVSMC proliferation. PMID:22427510
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Sun, Wei; Qiao, Kai; Liu, Ji-Yuan; Cao, Li-Mei; Gong, Xue-Qing; Yang, Ji
2016-04-11
H2 selective catalytic reduction (H2-SCR) has been proposed as a promising technology for controlling NOx emission because hydrogen is clean and does not emit greenhouse gases. We demonstrate that Pt doped into a nickel ferrite spinel structure can afford a high catalytic activity of H2-SCR. A superior NO conversion of 96% can be achieved by employing a novel NiFe1.95Pt0.05O4 spinel-type catalyst at 60 °C. This novel catalyst is different from traditional H2-SCR catalysts, which focus on the role of metallic Pt species and neglect the effect of oxidized Pt states in the reduction of NO. The obtained Raman and XPS spectra indicate that Pt in the spinel lattice has different valence states with Pt(2+) occupying the tetrahedral sites and Pt(4+) residing in the octahedral ones. These oxidation states of Pt enhance the back-donation process, and the lack of filling electrons of the 5d band causes Pt to more readily hybridize with the 5σ orbital of the NO molecule, especially for octahedral Pt(4+), which enhances the NO chemisorption on the Pt sites. We also performed DFT calculations to confirm the enhancement of adsorption of NO onto Pt sites when doped into the Ni-Fe spinel structure. The prepared Pt/Ni-Fe catalysts indicate that increasing the dispersity of Pt on the surfaces of the individual Ni-Fe spinel-type catalysts can efficiently promote the H2-SCR activity. Our demonstration provides new insight into designing advanced catalysts for H2-SCR.
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40 CFR 75.12 - Specific provisions for monitoring NOX emission rate.
Code of Federal Regulations, 2010 CFR
2010-07-01
...) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Monitoring Provisions § 75.12 Specific provisions for monitoring NOX emission rate. (a) Coal-fired units, gas-fired nonpeaking units or oil-fired... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Specific provisions for monitoring NOX...
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40 CFR 75.12 - Specific provisions for monitoring NOX emission rate.
Code of Federal Regulations, 2013 CFR
2013-07-01
...) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Monitoring Provisions § 75.12 Specific provisions for monitoring NOX emission rate. (a) Coal-fired units, gas-fired nonpeaking units or oil-fired... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Specific provisions for monitoring NOX...
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40 CFR 75.12 - Specific provisions for monitoring NOX emission rate.
Code of Federal Regulations, 2014 CFR
2014-07-01
...) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Monitoring Provisions § 75.12 Specific provisions for monitoring NOX emission rate. (a) Coal-fired units, gas-fired nonpeaking units or oil-fired... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Specific provisions for monitoring NOX...
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40 CFR 75.12 - Specific provisions for monitoring NOX emission rate.
Code of Federal Regulations, 2011 CFR
2011-07-01
...) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Monitoring Provisions § 75.12 Specific provisions for monitoring NOX emission rate. (a) Coal-fired units, gas-fired nonpeaking units or oil-fired... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Specific provisions for monitoring NOX...
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40 CFR 75.12 - Specific provisions for monitoring NOX emission rate.
Code of Federal Regulations, 2012 CFR
2012-07-01
...) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Monitoring Provisions § 75.12 Specific provisions for monitoring NOX emission rate. (a) Coal-fired units, gas-fired nonpeaking units or oil-fired... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Specific provisions for monitoring NOX...
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NASA Astrophysics Data System (ADS)
Padmalekha, K. G.; Huang, H.; Ellmers, I.; Pérez Vélez, R.; van Leusen, J.; Brückner, A.; Grünert, W.; Schünemann, V.
2017-11-01
Iron loaded zeolites like Fe-ZSM-5 are potent candidates for the catalytic abatement of nitrogen oxides from car exhaust, e.g. from Diesel engines. Recent problems in this field show that there is an urgent need in further improvement of such catalysts, for which a full analysis of Fe species present in them under different conditions is highly desirable. We have studied Fe-ZSM-5 catalysts prepared via solid-state ion exchange by using field dependent Mössbauer spectroscopy at low temperature in order to identify the different iron species present in this type of catalyst in the fresh state and after use in catalysis. Mössbauer spectroscopy proved to be the key technique for a full understanding of species structures, but due to the complexity of structures, guidance by parallel EPR experiments and control by SQUID magnetometry were essential to prove reliability of derived species distributions.
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Evidence of the Importance of Nox4 in Production of Hypertension in Dahl Salt-Sensitive Rats.
Cowley, Allen W; Yang, Chun; Zheleznova, Nadezhda N; Staruschenko, Alexander; Kurth, Theresa; Rein, Lisa; Kumar, Vikash; Sadovnikov, Katherine; Dayton, Alex; Hoffman, Matthew; Ryan, Robert P; Skelton, Meredith M; Salehpour, Fahimeh; Ranji, Mahsa; Geurts, Aron
2016-02-01
This study reports the consequences of knocking out NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 4 (Nox4) on the development of hypertension and kidney injury in the Dahl salt-sensitive (SS) rat. Zinc finger nuclease injection of single-cell SS embryos was used to create an 8 base-pair frame-shift deletion of Nox4, resulting in a loss of the ≈68 kDa band in Western blot analysis of renal cortical tissue of the knock out of Nox4 in the SS rat (SS(Nox4-/-)) rats. SS(Nox4-/-) rats exhibited a significant reduction of salt-induced hypertension compared with SS rats after 21 days of 4.0% NaCl diet (134±5 versus 151±3 mm Hg in SS) and a significant reduction of albuminuria, tubular casts, and glomerular injury. Optical fluorescence 3-dimensional cryoimaging revealed significantly higher redox ratios (NADH/FAD [reduced nicotinamide adenine dinucleotide/flavin adenine dinucleotide]) in the kidneys of SS(Nox4-/-) rats even when fed the 0.4% NaCl diet, indicating greater levels of mitochondrial electron transport chain metabolic activity and reduced oxidative stress compared with SS rats. Before the development of hypertension, RNA expression levels of Nox subunits Nox2, p67(phox), and p22(phox) were found to be significantly lower (P<0.05) in SS(Nox4-/-) compared with SS rats in the renal cortex. Thus, the mutation of Nox4 seems to modify transcription of several genes in ways that contribute to the protective effects observed in the SS(Nox4-/-) rats. We conclude that the reduced renal injury and attenuated blood pressure response to high salt in the SS(Nox4-/-) rat could be the result of multiple pathways, including gene transcription, mitochondrial energetics, oxidative stress, and protein matrix production impacted by the knock out of Nox4. © 2015 American Heart Association, Inc.
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A GdAlO3 Perovskite Oxide Electrolyte-Based NOx Solid-State Sensor
NASA Astrophysics Data System (ADS)
Xiao, Yihong; Wang, Dongmei; Cai, Guohui; Zheng, Yong; Zhong, Fulan
2016-11-01
NOx is a notorious emission from motor vehicles and chemical factories as the precursor of acid rain and photochemical smog. Although zirconia-based NOx sensors have been developed and showed high sensitivity and selectivity at a high temperature of above 800 °C, they fail to show good performance, and even don’t work at the typical work temperature window of the automotive engine (<500 °C). It still is a formidable challenge for development of mild-temperature NOx detector or sensor. Herein, a novel amperometric solid-state NOx sensor was developed using perovskite-type oxide Gd1-xCaxAlO3-δ(GCA) as the electrolyte and NiO as the sensing electrode. NOx sensing properties of the device were investigated at the temperature region of 400-500 °C. The response current value at -300 mV was almost linearly proportional to the NOx concentration between 300 and 500 ppm at 500 °C. At such a temperature, the optimal sensor gave the highest NO2 sensitivity of 20.15 nA/ppm, and the maximum response current value reached 5.57 μA. Furthermore, a 90% response and 90% recover time to 500 ppm NO2 were about 119 and 92 s, respectively. The excellent selectivity and stability towards NOx sensing showed the potential application of the sensor in motor vehicles.
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40 CFR 60.4320 - What emission limits must I meet for nitrogen oxides (NOX)?
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 6 2010-07-01 2010-07-01 false What emission limits must I meet for nitrogen oxides (NOX)? 60.4320 Section 60.4320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... nitrogen oxides (NOX)? (a) You must meet the emission limits for NOX specified in Table 1 to this subpart...
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40 CFR 60.4320 - What emission limits must I meet for nitrogen oxides (NOX)?
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 6 2011-07-01 2011-07-01 false What emission limits must I meet for nitrogen oxides (NOX)? 60.4320 Section 60.4320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... nitrogen oxides (NOX)? (a) You must meet the emission limits for NOX specified in Table 1 to this subpart...
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40 CFR 60.4320 - What emission limits must I meet for nitrogen oxides (NOX)?
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 7 2013-07-01 2013-07-01 false What emission limits must I meet for nitrogen oxides (NOX)? 60.4320 Section 60.4320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... nitrogen oxides (NOX)? (a) You must meet the emission limits for NOX specified in Table 1 to this subpart...
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40 CFR 60.4320 - What emission limits must I meet for nitrogen oxides (NOX)?
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 7 2014-07-01 2014-07-01 false What emission limits must I meet for nitrogen oxides (NOX)? 60.4320 Section 60.4320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... nitrogen oxides (NOX)? (a) You must meet the emission limits for NOX specified in Table 1 to this subpart...
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40 CFR 60.4320 - What emission limits must I meet for nitrogen oxides (NOX)?
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 7 2012-07-01 2012-07-01 false What emission limits must I meet for nitrogen oxides (NOX)? 60.4320 Section 60.4320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... nitrogen oxides (NOX)? (a) You must meet the emission limits for NOX specified in Table 1 to this subpart...
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Federal NOx Budget Trading Program and CAIR NOx and SO2 Trading Programs (40 CFR Part 97)
This part establishes general provisions and the applicability, permitting, allowance, excess emissions, monitoring, and opt-in provisions for the federal NOx Budget Trading Program as a means of mitigating interstate transport of ozone and nitrogen oxides
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Low NO/x/ heavy fuel combustor program
NASA Technical Reports Server (NTRS)
Lister, E.; Niedzwiecki, R. W.; Nichols, L.
1980-01-01
The paper deals with the 'Low NO/x/ Heavy Fuel Combustor Program'. Main program objectives are to generate and demonstrate the technology required to develop durable gas turbine combustors for utility and industrial applications, which are capable of sustained, environmentally acceptable operation with minimally processed petroleum residual fuels. The program will focus on 'dry' reductions of oxides of nitrogen (NO/x/), improved combustor durability and satisfactory combustion of minimally processed petroleum residual fuels. Other technology advancements sought include: fuel flexibility for operation with petroleum distillates, blends of petroleum distillates and residual fuels, and synfuels (fuel oils derived from coal or shale); acceptable exhaust emissions of carbon monoxide, unburned hydrocarbons, sulfur oxides and smoke; and retrofit capability to existing engines.
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Enhanced Oxidation Capacity from Photolytic HOx/NOx Recycling: Implications for CH4 Growth
NASA Astrophysics Data System (ADS)
Madronich, S.
2017-12-01
Oxidation by OH radicals converts many emitted compounds (CO, CH4, VOCs as well as NOx, SO2, HCFCs, and others) to more soluble forms that can be removed rapidly from the atmosphere, e.g., by deposition. In a chemically stable atmosphere (without runaway concentration growth) the rate of OH production must generally exceed the emission rates of the reduced compounds, but secondary chemistry complicates OH budgets. If emission rates (e.g., E for CH4) increase, OH concentrations can either decrease or increase depending on NOx conditions, causing a non-linear dependence of CH4 concentrations on its emissions, [CH4] Ef where f, the methane feedback factor, is currently estimated in global 3d models to be 1.3-1.4. This feature is robust among models, and can be reproduced in simpler box models with the canonical Ox-HOx-NOx chemistry, in which global OH is increased by NOx emissions and decreased by CO, CH4, and VOC emissions. Scenarios with lower NOx emissions but higher CH4 emissions point to substantially lower global oxidation capacity in the future. Several newly hypothesized processes have attracted attention in recent years, including the photolytic recycling of OH from biogenic VOCs, and the photolysis of particulate nitrates to regenerate NOx. The latter process could be particularly significant in regions far from NOx emissions, where low NOx levels are more efficient at generating O3 and OH. To the extent that these processes do occur, they may provide some buffering of global OH against CH4 variations (f nearer 1), and more generally against anthropogenic perturbations. However, critical measurements from both lab and field are needed to assess the importance of these proposed processes.
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Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine
DOE Office of Scientific and Technical Information (OSTI.GOV)
Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.
Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH 3 production via a passivemore » SCR approach is of interest. In a passive SCR system, NH 3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH 3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH 3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH 3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH 3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH 3 generation further resulted in even higher NOX conversion; however, tailpipe NH 3 emissions resulted. At higher underfloor temperatures, NH 3 oxidation over the SCR limited NH 3 availability for NOX reduction. At the engine conditions studied, greater than 99 % NOX conversion was achieved with passive SCR while
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Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine
Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.; ...
2016-04-05
Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH 3 production via a passivemore » SCR approach is of interest. In a passive SCR system, NH 3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH 3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH 3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH 3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH 3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH 3 generation further resulted in even higher NOX conversion; however, tailpipe NH 3 emissions resulted. At higher underfloor temperatures, NH 3 oxidation over the SCR limited NH 3 availability for NOX reduction. At the engine conditions studied, greater than 99 % NOX conversion was achieved with passive SCR while
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NOx emissions from a Central California dairy
NASA Astrophysics Data System (ADS)
Hasson, Alam S.; Ogunjemiyo, Segun O.; Trabue, Steven; Ashkan, Shawn; Scoggin, Kenwood; Steele, Julie; Olea, Catalina; Middala, Srikar; Vu, Kennedy; Scruggs, Austen; Addala, Laxmi R.; Nana, Lucien
2013-05-01
Concentrations of NOx (NO + NO2) were monitored downwind from a Central California dairy facility during 2011 and 2012. NOx concentrations at the dairy were significantly higher than the background levels during August 2011 primarily due to the presence of elevated NO, but were indistinguishable from background concentrations during January and April 2012. A Gaussian plume model (AERMOD) and a Lagrangian back trajectory model (Wind Trax) were used to estimate the flux of NO from the dairy during August 2011 with the assumption that emissions were primarily from animal feed. NO emissions from silage were also directly measured from feed to provide additional insight into the sources. Isolation flux chamber measurements imply an NO flux from the feed of about 1.3 × 10-3 g m-2 h-1, but these relatively low fluxes are inconsistent with the elevated NO concentrations observed during August 2011. This implies that either the flux chamber method grossly underestimates the true NO emissions from feed, or that most of the ambient NO measured at the dairy is from other sources. Emissions from farm machinery may account for the NO concentrations observed. Animal feed thus appears to be a small contributor to NOx emissions within Central California.
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CFD analysis of jet mixing in low NOx flametube combustors
NASA Technical Reports Server (NTRS)
Talpallikar, M. V.; Smith, C. E.; Lai, M. C.; Holdeman, J. D.
1991-01-01
The Rich-burn/Quick-mix/Lean-burn (RQL) combustor was identified as a potential gas turbine combustor concept to reduce NO(x) emissions in High Speed Civil Transport (HSCT) aircraft. To demonstrate reduced NO(x) levels, cylindrical flametube versions of RQL combustors are being tested at NASA Lewis Research Center. A critical technology needed for the RQL combustor is a method of quickly mixing by-pass combustion air with rich-burn gases. Jet mixing in a cylindrical quick-mix section was numerically analyzed. The quick-mix configuration was five inches in diameter and employed twelve radial-inflow slots. The numerical analyses were performed with an advanced, validated 3-D Computational Fluid Dynamics (CFD) code named REFLEQS. Parametric variation of jet-to-mainstream momentum flux ratio (J) and slot aspect ratio was investigated. Both non-reacting and reacting analyses were performed. Results showed mixing and NO(x) emissions to be highly sensitive to J and slot aspect ratio. Lowest NO(x) emissions occurred when the dilution jet penetrated to approximately mid-radius. The viability of using 3-D CFD analyses for optimizing jet mixing was demonstrated.
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FreedomCAR - Aftertreatment Subsystem Development
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lisa A. Prentiss
2005-09-30
The primary objective of this program was to develop generic aftertreatment technologies applicable for LDV and LDT engines ranging from 55 kW to 200kW, to develop an optimized and integrated aftertreatment system for a LDT (Light Duty Truck) type vehicle, and to demonstrate the technology which will enable light duty diesel engines to meet Federal Tier II regulation with minimum impact on fuel economy. Specifically, the development targets for emissions reduction and fuel injection penalty are given below: (1) NOx conversion efficiency > 90% (hot), > 84% (combined); (2) PM conversion efficiency > 90% (hot), > 84% (combined); (3) Fuelmore » penalty over FTP-75 Less than 5%; and (4) Fuel penalty at Cruise condition Less than 3%. Development of cost-effective, highly efficient diesel exhaust aftertreatment systems in combination with very low engine out emission combustion development are essential elements for realization of Federal Tier II emission standards for Light Duty Trucks and Vehicles. Evaluation of several aftertreatment technologies was completed as part of this program. A combination of Diesel Oxidation Catalyst, NOx Adsorbing Catalyst and Catalyzed Soot Filter was found to provide the levels of conversion efficiency required to achieve the emission targets. While early systems required relatively large catalyst volumes, external dosing, sulfur traps, full bypass configurations and high levels of Platinum metals; the final system is a compact, scalable, flow-through, fully-integrated and engine-managed aftertreatment system capable of commercial application for Light Duty Vehicles and Trucks. NOx adsorber/particulate filter technology is particularly attractive for Light Duty applications due to the lower exhaust flow and temperature requirements as compared to Heavy Duty engines. Despite these strong positive aspects, NOx Adsorbers are challenged by their regeneration requirements and susceptibility to sulfur poisoning and thermal degradation
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The NOx dependence of bromine chemistry in the Arctic atmospheric boundary layer
NASA Astrophysics Data System (ADS)
Custard, K. D.; Thompson, C. R.; Pratt, K. A.; Shepson, P. B.; Liao, J.; Huey, L. G.; Orlando, J. J.; Weinheimer, A. J.; Apel, E.; Hall, S. R.; Flocke, F.; Mauldin, L.; Hornbrook, R. S.; Pöhler, D.; S., General; Zielcke, J.; Simpson, W. R.; Platt, U.; Fried, A.; Weibring, P.; Sive, B. C.; Ullmann, K.; Cantrell, C.; Knapp, D. J.; Montzka, D. D.
2015-09-01
Arctic boundary layer nitrogen oxides (NOx = NO2 + NO) are naturally produced in and released from the sunlit snowpack and range between 10 to 100 pptv in the remote background surface layer air. These nitrogen oxides have significant effects on the partitioning and cycling of reactive radicals such as halogens and HOx (OH + HO2). However, little is known about the impacts of local anthropogenic NOx emission sources on gas-phase halogen chemistry in the Arctic, and this is important because these emissions can induce large variability in ambient NOx and thus local chemistry. In this study, a zero-dimensional photochemical kinetics model was used to investigate the influence of NOx on the unique springtime halogen and HOx chemistry in the Arctic. Trace gas measurements obtained during the 2009 OASIS (Ocean - Atmosphere - Sea Ice - Snowpack) field campaign at Barrow, AK were used to constrain many model inputs. We find that elevated NOx significantly impedes gas-phase halogen radical-based depletion of ozone, through the production of a variety of reservoir species, including HNO3, HO2NO2, peroxyacetyl nitrate (PAN), BrNO2, ClNO2 and reductions in BrO and HOBr. The effective removal of BrO by anthropogenic NOx was directly observed from measurements conducted near Prudhoe Bay, AK during the 2012 Bromine, Ozone, and Mercury Experiment (BROMEX). Thus, while changes in snow-covered sea ice attributable to climate change may alter the availability of molecular halogens for ozone and Hg depletion, predicting the impact of climate change on polar atmospheric chemistry is complex and must take into account the simultaneous impact of changes in the distribution and intensity of anthropogenic combustion sources. This is especially true for the Arctic, where NOx emissions are expected to increase because of increasing oil and gas extraction and shipping activities.
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The NOx dependence of bromine chemistry in the Arctic atmospheric boundary layer
NASA Astrophysics Data System (ADS)
Custard, K. D.; Thompson, C. R.; Pratt, K. A.; Shepson, P. B.; Liao, J.; Huey, L. G.; Orlando, J. J.; Weinheimer, A. J.; Apel, E.; Hall, S. R.; Flocke, F.; Mauldin, L.; Hornbrook, R. S.; Pöhler, D.; General, S.; Zielcke, J.; Simpson, W. R.; Platt, U.; Fried, A.; Weibring, P.; Sive, B. C.; Ullmann, K.; Cantrell, C.; Knapp, D. J.; Montzka, D. D.
2015-03-01
Arctic boundary layer nitrogen oxides (NOx = NO2 + NO) are naturally produced in and released from the sunlit snowpack and range between 10 to 100 pptv in the remote background surface layer air. These nitrogen oxides have significant effects on the partitioning and cycling of reactive radicals such as halogens and HOx (OH + HO2). However, little is known about the impacts of local anthropogenic NOx emission sources on gas-phase halogen chemistry in the Arctic, and this is important because these emissions can induce large variability in ambient NOx and thus local chemistry. In this study, a zero-dimensional photochemical kinetics model was used to investigate the influence of NOx on the unique springtime halogen and HOx chemistry in the Arctic. Trace gas measurements obtained during the 2009 OASIS (Ocean-Atmosphere-Sea Ice-Snowpack) field campaign at Barrow, AK were used to constrain many model inputs. We find that elevated NOx significantly impedes gas-phase radical chemistry, through the production of a variety of reservoir species, including HNO3, HO2NO2, peroxyacetyl nitrate (PAN), BrNO2, ClNO2 and reductions in BrO and HOBr, with a concomitant, decreased net O3 loss rate. The effective removal of BrO by anthropogenic NOx was directly observed from measurements conducted near Prudhoe Bay, AK during the 2012 Bromine, Ozone, and Mercury Experiment (BROMEX). Thus, while changes in snow-covered sea ice attributable to climate change may alter the availability of molecular halogens for ozone and Hg depletion, predicting the impact of climate change on polar atmospheric chemistry is complex and must take into account the simultaneous impact of changes in the distribution and intensity of anthropogenic combustion sources. This is especially true for the Arctic, where NOx emissions are expected to increase because of increasing oil and gas extraction and shipping activities.
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Oxidative stress and hepatic Nox proteins in chronic hepatitis C and hepatocellular carcinoma
Choi, Jinah; Corder, Nicole L. B.; Koduru, Bhargav; Wang, Yiyan
2014-01-01
Hepatocellular carcinoma (HCC) is the most common liver cancer and a leading cause of cancer-related mortality in the world. Hepatitis C virus (HCV) is a major etiologic agent of HCC. A majority of HCV infections lead to chronic infection that can progress to cirrhosis and eventually, HCC and liver failure. A common pathogenic feature present in HCV infection, and other conditions leading to HCC, is oxidative stress. HCV directly increases superoxide and H2O2 formation in hepatocytes by elevating Nox protein expression and sensitizing mitochondria to reactive oxygen species generation while decreasing glutathione. Nitric oxide synthesis and hepatic iron are also elevated. Furthermore, activation of phagocytic NADPH oxidase 2 (Nox2) of host immune cells is likely to exacerbate oxidative stress in HCV-infected patients. Key mechanisms of HCC include: genome instability, epigenetic regulation, inflammation with chronic tissue injury and sustained cell proliferation, and modulation of cell growth and death. Oxidative stress, or Nox proteins, plays various roles in these mechanisms. Nox proteins also function in hepatic fibrosis, which commonly precedes HCC, and Nox4 elevation by HCV was mediated by transforming growth factor beta. This review summarizes mechanisms of oncogenesis by HCV, highlighting the role of oxidative stress and hepatic Nox enzymes in HCC. PMID:24816297
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Analysis of NOx Budget Trading Program Units Brought into the CAIR NOx Ozone Season Trading Program
EPA analyzed the effect of having the large non-EGU units in the NBP and the CAIR NOX ozone season trading program and evaluated whether or not emissions from this group of units were reduced as a result of their inclusion in those trading programs.
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Effect of air-staging on anthracite combustion and NOx formation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Weidong Fan; Zhengchun Lin; Youyi Li
Experiments were carried out in a multipath air inlet one-dimensional furnace to assess NOx emission characteristics of the staged combustion of anthracite coal. These experiments allowed us to study the impact of pulverized coal fineness and burnout air position on emission under both deep and shallow air-staged combustion conditions. We also studied the impact of char-nitrogen release on both the burning-out process of the pulverized coal and the corresponding carbon content in fly ash. We found that air-staged combustion affects a pronounced reduction in NOx emissions from the combustion of anthracite coal. The more the air is staged, the moremore » NOx emission is reduced. In shallow air-staged combustion (f{sub M} = 0.85), the fineness of the pulverized coal strongly influences emissions, and finer coals result in lower emissions. Meanwhile, the burnout air position has only a weak effect. In the deep air-staged combustion (f{sub M} = 0.6), the effect of coal fineness is smaller, and the burnout air position has a stronger effect. When the primary combustion air is stable, NOx emissions increase with increasing burnout air. This proves that, in the burnout zone, coal char is responsible for the discharge of fuel-nitrogen that is oxidized to NOx. The measurement of secondary air staging in a burnout zone can help inhibit the oxidization of NO caused by nitrogen release. Air-staged combustion has little effect on the burnout of anthracite coal, which proves to be suitable for air-staged combustion. 31 refs., 11 figs., 1 tab.« less
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Radiative forcing from aircraft NOx emissions: Mechanisms and seasonal dependence
NASA Astrophysics Data System (ADS)
Stevenson, David S.; Doherty, Ruth M.; Sanderson, Michael G.; Collins, William J.; Johnson, Colin E.; Derwent, Richard G.
2004-09-01
A chemistry-climate model has been applied to study the radiative forcings generated by aircraft NOx emissions through changes in ozone and methane. Four numerical experiments, where an extra pulse of aircraft NOx was emitted into the model atmosphere for a single month (January, April, July, or October), were compared to a control experiment, allowing the aircraft impact to be isolated. The extra NOx produces a short-lived (few months) pulse of ozone that generates a positive radiative forcing. However, the NOx and O3 both generate OH, which leads to a reduction in CH4. A detailed analysis of the OH budget reveals the spatial structure and chemical reactions responsible for the generation of the OH perturbation. Methane's long lifetime means that the CH4 anomaly decays slowly (perturbation lifetime of 11.1 years). The negative CH4 anomaly also has an associated negative O3 anomaly, and both of these introduce a negative radiative forcing. There are important seasonal differences in the response of O3 and CH4 to aircraft NOx, related to the annual cycle in photochemistry; the O3 radiative forcing calculations also have a seasonal dependence. The long-term globally integrated annual mean net forcing calculated here is approximately zero, although earlier work suggests a small net positive forcing. The model design (e.g., upper tropospheric chemistry, convection parameterization) and experimental setup (pulse magnitude and duration) may somewhat influence the results: further work with a range of models is required to confirm these results quantitatively.
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A site-directed mutagenesis analysis of tNOX functional domains
NASA Technical Reports Server (NTRS)
Chueh, Pin-Ju; Morre, Dorothy M.; Morre, D. James
2002-01-01
Constitutive NADH oxidase proteins of the mammalian cell surface exhibit two different activities, oxidation of hydroquinones (or NADH) and protein disulfide-thiol interchange which alternate to yield oscillatory patterns with period lengths of 24 min. A drug-responsive tNOX (tumor-associated NADH oxidase) has a period length of about 22 min. The tNOX cDNA has been cloned and expressed. These two proteins are representative of cycling oxidase proteins of the plant and animal cell surface. In this report, we describe a series of eight amino acid replacements in tNOX which, when expressed in Escherichia coli, were analyzed for enzymatic activity, drug response and period length. Replacement sites selected include six cysteines that lie within the processed plasma membrane (34 kDa) form of the protein, and amino acids located in putative drug and adenine nucleotide (NADH) binding domains. The latter, plus two of the cysteine replacements, resulted in a loss of enzymatic activity. The recombinant tNOX with the modified drug binding site retained activity but the activity was no longer drug-responsive. The four remaining cysteine replacements were of interest in that both activity and drug response were retained but the period length for both NADH oxidation and protein disulfide-thiol interchange was increased from 22 min to 36 or 42 min. The findings confirm the correctness of the drug and adenine nucleotide binding motifs within the tNOX protein and imply a potential critical role of cysteine residues in determining the period length.
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NASA Technical Reports Server (NTRS)
Wang, S.; Pogue, R.; Morre, D. M.; Morre, D. J.
2001-01-01
NOX proteins are cell surface-associated and growth-related hydroquinone (NADH) oxidases with protein disulfide-thiol interchange activity. A defining characteristic of NOX proteins is that the two enzymatic activities alternate to generate a regular period length of about 24 min. HeLa cells exhibit at least two forms of NOX. One is tumor-associated (tNOX) and is inhibited by putative quinone site inhibitors (e.g., capsaicin or the antitumor sulfonylurea, LY181984). Another is constitutive (CNOX) and refractory to inhibition. The periodic alternation of activities and drug sensitivity of the NADH oxidase activity observed with intact HeLa cells was retained in isolated plasma membranes and with the solubilized and partially purified enzyme. At least two activities were present. One had a period length of 24 min and the other had a period length of 22 min. The lengths of both the 22 and the 24 min periods were temperature compensated (approximately the same when measured at 17, 27 or 37 degrees C) whereas the rate of NADH oxidation approximately doubled with each 10 degrees C rise in temperature. The rate of increase in cell area of HeLa cells when measured by video-enhanced light microscopy also exhibited a complex period of oscillations reflective of both 22 and 24 min period lengths. The findings demonstrate the presence of a novel oscillating NOX activity at the surface of cancer cells with a period length of 22 min in addition to the constitutive NOX of non-cancer cells and tissues with a period length of 24 min.
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NO oxidation on Zeolite Supported Cu Catalysts: Formation and Reactivity of Surface Nitrates
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton
2016-04-18
The comparative activities of a small-pore Cu-CHA and a large-pore Cu-BEA catalyst for the selective catalytic reduction (SCR) of NOx with NH3, and for the oxidation of NO to NO2 and the subsequent formation of surface nitrates were investigated. Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity. Furthermore, Cu-CHA is even less active than Cu-BEA in catalyzing NO oxidation but is clearly more active for SCR reactions. Temperature-programed desorption (TPD) experiments following the adsorption of (NO2 + NO + O2) with different NO2:NO ratios reveal that the poor NO oxidation activity ofmore » the two catalysts is not due to the formation of stable surface nitrates. On the contrary, NO is found to reduce and decompose the surface nitrates on both catalysts. To monitor the reaction pathways, isotope exchange experiments were conducted by using 15NO to react with 14N-nitrate covered catalyst surfaces. The evolution of FTIR spectra during the isotope exchange process demonstrates that 14N-nitrates are simply displaced with no formation of 15N-nitrates on the Cu-CHA sample, which is clearly different from that observed on the Cu-BEA sample where formation of 15N-nitrates is apparent. The results suggest that the formal oxidation state of N during the NO oxidation on Cu-CHA mainly proceeds from its original +2 to a +3 oxidation state, whereas reaching a higher oxidation state for N, such as +4 or +5, is possible on Cu-BEA. The authors at PNNL gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.« less
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Volatile Release from the Siberian Traps Inferred from Melt Inclusions
NASA Astrophysics Data System (ADS)
Black, B. A.; Elkins-Tanton, L. T.; Rowe, M. C.; Ukstins Peate, I.
2009-12-01
compounds (CFCs) may have played a major role in the terrestrial end-Permian extinction. These CFCs are powerful catalysts for the breakdown of ozone, a process which can expose the biosphere to increased ultraviolet radiation. Measurements of elevated chlorine and fluorine from the Siberian Traps may thus provide a concrete source for CFCs that could have triggered this kill mechanism.
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Ellison, Michael A; Thurman, Gail; Gearheart, Christy M; Seewald, Ryan H; Porter, Christopher C; Ambruso, Daniel R
2015-01-01
The cytokine and drug interferon-γ enhances superoxide anion production by the antimicrobicidal Nox2 enzyme of neutrophils. Because mature neutrophils have a short lifespan, we hypothesized that the effects of interferon-γ on these cells might be mediated by its prolonged exposure to differentiating neutrophil precursors in the bone marrow rather than its brief exposure to mature circulating neutrophils. Effects of INF-Γ on NOX2 activity: To address this possibility we exposed the myeloid PLB-985 cell line to interferon-γ for 3 days in the presence of dimethyl sulfoxide which induces terminal differentiation of these cells. Interferon-γ was found to enhance superoxide production by Nox2 in a concentration dependent manner. In contrast, application of interferon-γ alone for 3 days failed to induce detectible Nox2 activity. Additionally, application of interferon-γ for 3 hours to pre-differentiated PLB-985 cells, which models studies using isolated neutrophils, was much less effective at enhancing superoxide anion production. Effects of INF-Γ on phox protein levels: Addition of interferon-γ during differentiation was found to upregulate the Nox2 proteins gp91phox and p47phox in concert with elevated transcription of their genes. The p22phox protein was upregulated in the absence of increased transcription presumably reflecting stabilization resulting from binding to the elevated gp91phox. Thus, increased levels of gp91phox, p47phox and p22phox likely account for the interferon-γ mediated enhancement of dimethyl sulfoxide-induced Nox2 activity. In contrast, although interferon-γ alone also increased various phox proteins and their mRNAs, the pattern was very different to that seen with interferon-γ plus dimethyl sulfoxide. In particular, p47phox was not induced thus explaining the inability of interferon -γ alone to enhance Nox2 activity. Short application of interferon-γ to already differentiated cells failed to increase any phox proteins. Our findings