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https://www.readbyqxmd.com/read/28934707/investigating-sources-and-sinks-of-n2o-expression-from-freshwater-microbial-communities-in-urban-watershed-sediments
#1
Christopher Weisener, Jumin Lee, Subba Rao Chaganti, Thomas Reid, Nick Falk, Ken Drouillard
Wastewater treatment plants (WWTPs) serve as point-source inputs for a variety of nutrients often dominated by nitrogenous compounds as a result of anthropogenic influence. These effluents can impact biogeochemical cycles in freshwater estuaries, influencing microbial communities in both the water and sediment compartments. To assess the impact of point source nutrients, a transect of sediment and pore water samples were collected from 4 locations in the Little River Sub-watershed including locations above and below the Little River Pollution Control Plant (LRPCP)...
September 11, 2017: Chemosphere
https://www.readbyqxmd.com/read/28934608/chemical-free-fabrication-of-n-p-dual-doped-honeycomb-like-carbon-as-an-efficient-electrocatalyst-for-oxygen-reduction
#2
Lianwen Zhu, Jun Wu, Qiao Zhang, Xiangkui Li, Yiming Li, Xuebo Cao
Heteroatom-doped nanoporous carbons are now emerging as alternatives to platinum and its alloys as electrocatalysts to facilitate oxygen reduction reaction in metal-air batteries and fuel cells. However, the synthesis of nanoporous carbons usually involve in complicated procedures and intensive chemicals, which may dramatically raise their manufacture cost that even surpasses that of precious platinum. Herein, we demonstrate the single-step, chemical-free fabrication of N, P dualdoped honeycomb carbon that has hierarchically porous structure and oxygen electrocatalysis activity close to the benchmark Pt/C...
August 23, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28934286/denitrification-potential-of-the-eastern-oyster-microbiome-using-a-16s-rrna-gene-based-metabolic-inference-approach
#3
Ann Arfken, Bongkeun Song, Jeff S Bowman, Michael Piehler
The eastern oyster (Crassostrea virginica) is a foundation species providing significant ecosystem services. However, the roles of oyster microbiomes have not been integrated into any of the services, particularly nitrogen removal through denitrification. We investigated the composition and denitrification potential of oyster microbiomes with an approach that combined 16S rRNA gene analysis, metabolic inference, qPCR of the nitrous oxide reductase gene (nosZ), and N2 flux measurements. Microbiomes of the oyster digestive gland, the oyster shell, and sediments adjacent to the oyster reef were examined based on next generation sequencing (NGS) of 16S rRNA gene amplicons...
2017: PloS One
https://www.readbyqxmd.com/read/28931476/greenhouse-gas-and-ammonia-emissions-from-production-of-compost-bedding-on-a-dairy-farm
#4
M A Fillingham, A C VanderZaag, S Burtt, H Baldé, N M Ngwabie, W Smith, A Hakami, C Wagner-Riddle, S Bittman, D MacDonald
Recent developments in composting technology enable dairy farms to produce their own bedding from composted manure. This management practice alters the fate of carbon and nitrogen; however, there is little data available documenting how gaseous emissions are impacted. This study measured in-situ emissions of methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) from an on-farm solid-liquid separation system followed by continuously-turned plug-flow composting over three seasons. Emissions were measured separately from the continuously-turned compost phase, and the compost-storage phase prior to the compost being used for cattle bedding...
September 18, 2017: Waste Management
https://www.readbyqxmd.com/read/28930460/imaging-the-photodissociation-dynamics-of-nitrous-acid-hono-the-role-of-torsion
#5
Chandika Amarasinghe, Alexander Kamasah, Casey D Foley, James O F Thompson, Arthur G Suits
We present the findings of the first imaging study of trans-HONO and cis-HONO photodissociation through the band and of the 1A" -1A' transition. The NO photofragment was probed by (1+1) Resonance Enhanced Multiphoton Ionization (REMPI) and studied using the DC slice imaging technique with our Finite Slice reconstruction method (FinA). The NO state-specific translational energy distributions show some rotational structure corresponding to the internal state distribution in the OH co-fragment. All images showed a perpendicular angular distribution with a recoil anisotropy parameter around -0...
September 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28927704/the-catalytic-cycle-of-nitrous-oxide-reductase-the-enzyme-that-catalyzes-the-last-step-of-denitrification
#6
Cíntia Carreira, Sofia R Pauleta, Isabel Moura
The reduction of the potent greenhouse gas nitrous oxide requires a catalyst to overcome the large activation energy barrier of this reaction. Its biological decomposition to the inert dinitrogen can be accomplished by denitrifiers through nitrous oxide reductase, the enzyme that catalyzes the last step of the denitrification, a pathway of the biogeochemical nitrogen cycle. Nitrous oxide reductase is a multicopper enzyme containing a mixed valence CuA center that can accept electrons from small electron shuttle proteins, triggering electron flow to the catalytic sulfide-bridged tetranuclear copper "CuZ center"...
September 11, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28925700/infrared-signature-of-structural-isomers-of-gas-phase-m-n2o-n-m-cu-ag-au-ion-molecule-complexes
#7
Ethan M Cunningham, Alexander S Gentleman, Peter M Beardsmore, Andreas Iskra, Stuart R Mackenzie
Gas-phase metal ion-ligand complexes offer model environments to study molecular interactions which are key to many catalytic processes. Here, we present a combined experimental and computational study of M+(N2O)n [M= Cu, Ag, Au; n = 2-7] complexes. The spectra provide clear evidence for both nitrogen- and oxygen- bound ligands giving rise to a wide range of structural isomers for each complex studied. The evolution of the complex structures observed as well as spectral trends for each metal center are interpreted in terms of a molecular orbital binding picture and resulting calculated ligand binding energies...
September 19, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28925557/analysis-of-multiple-haloarchaeal-genomes-suggests-that-the-quinone-dependent-respiratory-nitric-oxide-reductase-is-an-important-source-of-nitrous-oxide-in-hypersaline-environments
#8
Javier Torregrosa-Crespo, Pedro González-Torres, Vanesa Bautista, Julia M Esclapez, Carmen Pire, Mónica Camacho, María José Bonete, David J Richardson, Nicholas J Watmough, Rosa María Martínez-Espinosa
Microorganisms, including Bacteria and Archaea, play a key role in denitrification, which is the major mechanism by which fixed nitrogen returns to the atmosphere from soil and water. Whilst the enzymology of denitrification is well understood in Bacteria, the details of the last two reactions in this pathway, which catalyse the reduction of nitric oxide (NO) via nitrous oxide (N2 O) to nitrogen (N2 ), are little studied in Archaea, and hardly at all in haloarchaea. This work describes an extensive interspecies analysis of both complete and draft haloarchaeal genomes aimed at identifying the genes that encode respiratory nitric oxide reductases (Nors)...
September 19, 2017: Environmental Microbiology Reports
https://www.readbyqxmd.com/read/28925551/clade-ii-nitrous-oxide-respiration-of-wolinella-succinogenes-depends-on-the-nosg-c1-c2-h-electron-transport-module-nosb-and-a-rieske-cytochrome-bc-complex
#9
Sascha Hein, Samantha Witt, Jörg Simon
Microbial reduction of nitrous oxide (N2 O) is an environmentally significant process in the biogeochemical nitrogen cycle. However, it has been recognized only recently that the gene encoding N2 O reductase (nosZ) is organized in varying genetic contexts, thereby defining clade I (or "typical") and clade II (or "atypical") N2 O reductases and nos gene clusters. This study addresses the enzymology of the clade II Nos system from Wolinella succinogenes, a nitrate-ammonifying and N2 O-respiring Epsilonproteobacterium that contains a cytochrome c N2 O reductase (cNosZ)...
September 19, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28917118/calibration-of-the-comprehensive-ndha-n2o-dynamics-model-for-nitrifier-enriched-biomass-using-targeted-respirometric-assays
#10
Carlos Domingo-Félez, Maria Calderó-Pascual, Gürkan Sin, Benedek G Plósz, Barth F Smets
The NDHA model comprehensively describes nitrous oxide (N2O) producing pathways by both autotrophic ammonium oxidizing and heterotrophic bacteria. The model was calibrated via a set of targeted extant respirometric assays using enriched nitrifying biomass from a lab-scale reactor. Biomass response to ammonium, hydroxylamine, nitrite and N2O additions under aerobic and anaerobic conditions were tracked with continuous measurement of dissolved oxygen (DO) and N2O. The sequential addition of substrate pulses allowed the isolation of oxygen-consuming processes...
September 7, 2017: Water Research
https://www.readbyqxmd.com/read/28915966/use-of-anthropogenic-nitrogen-fertilizers-in-agriculture-is-associated-with-per-capita-ethanol-consumption
#11
Keith Fluegge, Kyle Fluegge
It has previously been demonstrated that emissions of the agricultural pollutant, nitrous oxide (N2O), may be a confounder to the relationship between herbicide use and psychiatric impairments, including ADHD. This report attempts to extend this hypothesis by testing whether annual use of anthropogenic nitrogen-based fertilizers in U.S. agriculture (thought to be the most reliable indicator of environmental N2O emissions) is associated with per capita ethanol consumption patterns, a behavior often comorbid with ADHD...
September 2017: Medical Hypotheses
https://www.readbyqxmd.com/read/28914941/mid-infrared-fiber-optic-photothermal-interferometry
#12
Zhili Li, Zhen Wang, Fan Yang, Wei Jin, Wei Ren
We demonstrate mid-infrared photothermal interferometry (PTI) in a hollow-core fiber (HCF) for trace gas detection. Compared with free-space PTI, the optical intensity could be increased by orders of magnitude by confining the pump and probe lights in the hollow core. We coupled the pump light at 4.46 μm from a quantum cascade laser and the 1555.14 nm probe light into the HCF with a bore size of 200 μm. The HCF was filled with nitrous oxide (N2O) which has strong absorption at the pump wavelength. The probe light detects the N2O absorption-induced phase change in the HCF via a fiber-optic Mach-Zehnder interferometer...
September 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28914247/assessment-of-hypoxia-sedation-level-and-adverse-events-occurring-during-inhalation-sedation-using-preadjusted-mix-of-30-nitrous-oxide-70-oxygen
#13
P V Samir, Srinivas Namineni, P Sarada
PURPOSE: To assess the efficacy of nitrous oxide (N2O)-oxygen (O2) inhalation sedation by rapid induction technique using preadjusted mix of 30% N2O and 70% O2 in children. MATERIALS AND METHODS: Sixty children with a treatment plan which included pulp therapy were recruited for the study. Children categorized 3 and 4 of Frankl behavior rating scale and American Society of Anesthesiologists health status I and II were included for the study. Children were distributed into study group (Group-I) and control group (Group-II) by fishbowl randomization...
October 2017: Journal of the Indian Society of Pedodontics and Preventive Dentistry
https://www.readbyqxmd.com/read/28912756/fixk2-is-the-main-transcriptional-activator-of-bradyrhizobium-diazoefficiens-nosrzdyflx-genes-in-response-to-low-oxygen
#14
María J Torres, Emilio Bueno, Andrea Jiménez-Leiva, Juan J Cabrera, Eulogio J Bedmar, Socorro Mesa, María J Delgado
The powerful greenhouse gas, nitrous oxide (N2O) has a strong potential to drive climate change. Soils are the major source of N2O and microbial nitrification and denitrification the main processes involved. The soybean endosymbiont Bradyrhizobium diazoefficiens is considered a model to study rhizobial denitrification, which depends on the napEDABC, nirK, norCBQD, and nosRZDYFLX genes. In this bacterium, the role of the regulatory cascade FixLJ-FixK2-NnrR in the expression of napEDABC, nirK, and norCBQD genes involved in N2O synthesis has been previously unraveled...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28910713/beneficial-effect-of-compost-utilization-on-reducing-greenhouse-gas-emissions-in-a-rice-cultivation-system-through-the-overall-management-chain
#15
Seung Tak Jeong, Gil Won Kim, Hyun Young Hwang, Pil Joo Kim, Sang Yoon Kim
Livestock manure application can stimulate greenhouse gas (GHG) emissions, especially methane (CH4) in rice paddy. The stabilized organic matter (OM) is recommended to suppress CH4 emission without counting the additional GHG emission during the composting process. To evaluate the effect of compost utilization on the net global warming potential (GWP) of a rice cropping system, the fluxes of GHGs from composting to land application were calculated by a life cycle assessment (LCA) method. The model framework was composed of GHG fluxes from industrial activities and biogenic GHG fluxes from the composting and rice cultivation processes...
September 11, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28903174/greenhouse-gases-emission-from-the-sewage-draining-rivers
#16
Beibei Hu, Dongqi Wang, Jun Zhou, Weiqing Meng, Chongwei Li, Zongbin Sun, Xin Guo, Zhongliang Wang
Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentration, saturation and fluxes in rivers (Beitang drainage river, Dagu drainage rive, Duliujianhe river, Yongdingxinhe river and Nanyunhe river) of Tianjin city (Haihe watershed) were investigated during July and October in 2014, and January and April in 2015 by static headspace gas chromatography method and the two-layer model of diffusive gas exchange. The influence of environmental variables on greenhouse gases (GHGs) concentration under the disturbance of anthropogenic activities was discussed by Spearman correlative analysis and multiple stepwise regression analysis...
September 9, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28903087/control-strategies-for-nitrous-oxide-emissions-reduction-on-wastewater-treatment-plants-operation
#17
I Santín, M Barbu, C Pedret, R Vilanova
The present paper focused on reducing greenhouse gases emissions in wastewater treatment plants operation by application of suitable control strategies. Specifically, the objective is to reduce nitrous oxide emissions during the nitrification process. Incomplete nitrification in the aerobic tanks can lead to an accumulation of nitrite that triggers the nitrous oxide emissions. In order to avoid the peaks of nitrous oxide emissions, this paper proposes a cascade control configuration by manipulating the dissolved oxygen set-points in the aerobic tanks...
August 28, 2017: Water Research
https://www.readbyqxmd.com/read/28893505/inactivation-and-adaptation-of-ammonia-oxidizing-bacteria-and-nitrite-oxidizing-bacteria-when-exposed-to-free-nitrous-acid
#18
Bin Ma, Lan Yang, Qilin Wang, Zhiguo Yuan, Yayi Wang, Yongzhen Peng
Inactivation and adaptation of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to free nitrous acid (FNA) was investigated. Batch test results showed that AOB and NOB were inactivated when treated with FNA. After an 85-day operating period, AOB in a continuous pre-denitrification reactor did not adapt to the FNA that was applied to treat some of the return activated sludge. In contrast, NOB did adapt to FNA. NOB activity in the seed sludge was only 11% of the original activity after FNA batch treatment, at 0...
August 15, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28893018/changes-in-gas-composition-during-low-flow-anaesthesia-without-nitrous-oxide
#19
Ranjana Venkatachalapathy, Anusha Cherian, Sakthirajan Panneerselvam
INTRODUCTION: Low flow anaesthesia utilising Oxygen (O2) and Nitrous Oxide (N2O) mixture carries a risk of hypoxia, but avoiding N2O results in increased analgesic and volatile anaesthetic agent requirement. AIM: This study attempted to find the lowest Fraction of inspired Oxygen (FiO2) levels achieved with a mixture of 300 mL/min each of O2 and medical air over two hours and to compare the overall analgesic requirement and cost while using similar flows of N2O and O2, respectively...
July 2017: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28892687/effects-of-carbon-sources-and-cod-n-ratio-on-n2o-emissions-in-subsurface-flow-constructed-wetlands
#20
Wanlin Lyu, Lei Huang, Guangquan Xiao, Yucheng Chen
A set of constructed wetlands under two different carbon sources, namely, glucose (CW) and sodium acetate (YW), was established at a laboratory scale with influent COD/N ratios of 20:1, 10:1, 7:1, 4:1, and 0 to analyze the influence of carbon supply on nitrous oxide emissions. Results showed that the glucose systems generated higher N2O emissions than those of the sodium acetate systems. The higher amount of N2O-releasing fluxes in the CWs than in the YWs was consistent with the higher NO2(-)-N accumulation in the former than in the latter...
August 13, 2017: Bioresource Technology
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