Source Of Carbon Monoxide Research Articles

Palladium-catalyzed aminocarbonylation of 2-phenyimidazo[1,2-a] pyridines using chloroform as carbon monoxide source and their mechanistic studies

The synthesis of Imidazo[1,2-a]pyridine-3-carboxamides has been carried out by aminocarbonylation using chloroform as carbon monoxide surrogate. Reported protocol is simple, efficient, tolerates wide variety of substrates and the products were formed in good yields. The method can be exploited for the functionalisation of wide range of N-heterocycles with medicinal interest. The detailed mechanistic investigation of metal-catalyzed carboxamide preparation using Density Functional Theory (DFT) calculations has also been reported.

Implications of intense biomass burning over Uttarakhand in April–May 2016

A widespread forest fire episode occurred over Uttarakhand during April 24–May 2, 2016. This event released large amount of carbon monoxide (CO), nitrogen dioxide (NO2) and aerosols in the pristine environment of Uttarakhand. AIRS observations showed 60–125 ppbv higher CO during fire-impacted period with respect to background CO at 925, 850 and 700 hPa. Spatial distribution of CO and fire hotspots over Uttarakhand showed high level of CO over the region of intense biomass burning specifically. Over Dehradun, rate of increase in daily average surface CO was found to be 45 ppbv/day during fire period. Average background and fire-impacted tropospheric column NO2 were found to be 1.7 × 1015 ± 5.0 × 1014 mol/cm2 and 3.0 × 1015 ± 8.5 × 1014 mol/cm2, respectively. Similarly, average background and fire-impacted aerosol optical depth (AOD) were found to be 0.47 ± 0.25 and 0.90 ± 0.35, respectively, for Terra and 0.44 ± 0.17 and 0.86 ± 0.47, respectively, for Aqua observations. Size- and shape-segregated AOD distributions showed enhancement of medium-to-coarse (radius > 0.35 µm) non-spherical particles due to fire episode. CALIPSO height-resolved aerosol subtyping showed dominance of smoke near Uttarakhand up to 10 km altitude. Interspecies correlations indicated the common sources of near-surface CO, CO aloft, AOD and NO2. A relatively poor correlation between near-surface CO and tropospheric column NO2 might be due to chemical transformation of reactive NO2 within the fire plume. Forward trajectories calculated over fire-affected region at 500 m AGL indicated that fire emissions might have influenced the air quality of southern Nepal and northern Uttar Pradesh/Bihar within lower 3 km.

A Palladium-Catalyzed Cascade C-C Activation of Cyclopropenone and Carbonylative Amination: Easy Access to Highly Functionalized Maleimide Derivatives.

We describe herein the first report on palladium-catalyzed C-C bond activation of cyclopropenone and concomitant carbonylative amination to produce maleimides. The interesting aspect of this reaction is that the sacrificial elimination of carbon monoxide from the substrate is efficiently recaptured by one of the intermediates in the catalytic cycle for the formation of maleimides. 18O isotopic studies confirmed that the source of carbon monoxide is from cyclopropenone.

Carbon dioxide electroreduction on single-atom nickel decorated carbon membranes with industry compatible current densities

Carbon dioxide electroreduction provides a useful source of carbon monoxide, but comparatively few catalysts could be sustained at current densities of industry level. Herein, we construct a high-yield, flexible and self-supported single-atom nickel-decorated porous carbon membrane catalyst. This membrane possesses interconnected nanofibers and hierarchical pores, affording abundant effective nickel single atoms that participate in carbon dioxide reduction. Moreover, the excellent mechanical strength and well-distributed nickel atoms of this membrane combines gas-diffusion and catalyst layers into one architecture. This integrated membrane could be directly used as a gas diffusion electrode to establish an extremely stable three-phase interface for high-performance carbon dioxide electroreduction, producing carbon monoxide with a 308.4 mA cm−2 partial current density and 88% Faradaic efficiency for up to 120 h. We hope this work will provide guidance for the design and application of carbon dioxide electro-catalysts at the potential industrial scale.

Continuous flow synthesis of aryl aldehydes by Pd-catalyzed formylation of phenol-derived aryl fluorosulfonates using syngas.

This communication describes the palladium-catalyzed reductive carbonylation of aryl fluorosulfonates (ArOSO2F) using syngas as an inexpensive and sustainable source of carbon monoxide and hydrogen. The conversion of phenols to aryl fluorosulfonates can be conveniently achieved by employing the inexpensive commodity chemical sulfuryl fluoride (SO2F2) and base. The developed continuous flow formylation protocol requires relatively low loadings for palladium acetate (1.25 mol%) and ligand (2.5 mol%). Good to excellent yields of aryl aldehydes were obtained within 45 min for substrates containing electron withdrawing substituents, and 2 h for substrates containing electron donating substituents. The optimal reaction conditions were identified as 120 °C temperature and 20 bar pressure in dimethyl sulfoxide (DMSO) as solvent. DMSO was crucial in suppressing Pd black formation and enhancing reaction rate and selectivity.

CNTs growth on reduced iron

The mechanism of CNTs growth on iron catalyst is considered. Process occurs under conditions of low-temperature carbon monoxide disproportionation. Products of natural gas air conversion serve as a source of carbon monoxide. A highly dispersed structure of iron in the form of a chaotic accumulation of its particles is formed in terms of low-temperature reduction. The boundaries of contact of particles have the highest catalytic activity, where the nucleation of a new phase occurs in the form of ring-shaped cuffs due to emitted carbon while carbon monoxide decomposes. The optimum temperature regime for considered process lies in the range of 600–650 °C.

Palladium‐Catalyzed Thio‐ and Selenocarbonylation of 2‐Iodoglycals

AbstractThe carbonylative cross‐coupling reactions of 2‐iodoglycals with thiols and selenols in the presence of molybdenum hexacarbonyl as a solid source of carbon monoxide is described. This methodology permitted the synthesis of 29 C2‐glycosides bearing thioester and selenoester functionalities in moderate to excellent yields and high functional group tolerance. Moreover, this communication describes the first catalytic carbonylative coupling reaction of selenols with a carbon electrophile.

New constraints on biogenic emissions using satellite-based estimates of carbon monoxide fluxes

Abstract. Biogenic non-methane volatile organic compounds (NMVOCs) emitted from vegetation are a primary source for the chemical production of carbon monoxide (CO) in the atmosphere, and these biogenic emissions account for about 18 % of the global CO burden. Partitioning CO fluxes to different source types in top-down inversion methods is challenging; typically a simple scaling of the posterior flux to prior flux values for fossil fuel, biogenic and biomass burning sources is used. Here we show top-down estimates of biogenic CO fluxes using a Bayesian inference approach, which explicitly accounts for both posterior and a priori CO flux uncertainties. This approach re-partitions CO fluxes following inversion of Measurements Of Pollution In The Troposphere (MOPITT) CO observations with the GEOS-Chem model, a global chemical transport model driven by assimilated meteorology from the NASA Goddard Earth Observing System (GEOS). We compare these results to the prior information for CO used to represent biogenic NMVOCs from GEOS-Chem, which uses the Model of Emissions of Gases and Aerosols from Nature (MEGAN) for biogenic emissions. We evaluate the a posteriori biogenic CO fluxes against top-down estimates of isoprene fluxes using Ozone Monitoring Instrument (OMI) formaldehyde observations. We find similar seasonality and spatial consistency in the posterior CO and top-down isoprene estimates globally. For the African savanna region, both top-down CO and isoprene seasonality vary significantly from the MEGAN a priori inventory. This method for estimating biogenic sources of CO will provide an independent constraint on modeled biogenic emissions and has the potential for diagnosing decadal-scale changes in emissions due to land-use change and climate variability.

Structure-Dependent Modulation of Substrate Binding and Biodegradation Activity of Pirin Proteins toward Plant Flavonols.

Pirin is a nonheme metalloprotein that occurs widely in human tissues and is highly conserved across all taxa. Pirin proteins typically function as nuclear transcription regulators, but two Pirin orthologs, YhhW (from Escherichia coli) and hPirin (from humans) were revealed to possess enzymatic activity of degrading quercetin. The exact role of Pirin homologues and their catalytic specificity remain poorly understood. In this work, by screening against a panel of plant flavonoids, we found that both Pirins catalyze the oxidative degradation of a wide spectrum of flavonol analogues and release carbon monoxide (CO) in the process. This shows that Pirin acts on a broad range of substrates and could represent a novel dietary source of CO in vivo. Although the kinetic profiles differ substantially between two Pirins, the identified substrate structures all share a 2,3-double bond and 3-hydroxyl and 4-oxo groups on their "flavonol backbone," which contribute to the specific enzyme-substrate interaction. While hPirin is iron-dependent, YhhW is identified as a novel nickel-containing dioxygenase member of the bicupin family. Besides the expanded Pirin activity, we present the crystal structures of the native Ni-YhhW and tag-free Fe-hPirin, revealing the distinctive differences occurring at the metal-binding site. In addition, YhhW features a flexible Ω-loop near the catalytic cavity, which may help stabilize the reaction intermediates via a Ni-flavonol complex. The structure-dependent modulation of substrate binding to the catalytic cavity adds to understanding the differential dispositions of natural flavonols by human and bacterial Pirins.

Dependence of welding fume particle toxicity on electrode type and current intensity assessed by microalgae growth inhibition test

Welding fumes are a major source of metal oxide particles, ozone, carbon monoxide, carbon dioxide, nitrogen oxides, and many other toxic substances. Hazardous properties and the level of toxicity of welding fumes depend mostly on the welding electrode type and the welding regime parameters. The specific objective of this study was to evaluate the aquatic toxicity of metal welding fume particles in vivo on microalga Heterosigma akashiwo. The quantity and size of particles were measured by flow cytometry using a scattering laser light with a wavelength of 405 nm. The number of microalgae cells after 72 h and 7 days exposition with welding fume particle suspensions was evaluated by flow cytometry. Morphological changes of the microalga were observed by optical microscopy. The toxic effect was demonstrated as a significant reduction of cell density after exposure of microalgae to welding fume particles. The greatest impact on the growth of microalga was caused by particles with high rutile content. It was shown that the adverse effect of metal oxide particles depends more on the chemical composition of particles in welding fume while the number and dispersity of particles had no noticeable toxic influence on microalgae. The findings of this research confirm the fact that the toxicity of welding fume particles can be significantly reduced by using rutile-cellulose coated electrodes.

Palladium‐Catalyzed Aminocarbonylation Reaction to Access 1,2,3‐Triazole‐5‐carboxamides Using Dimethyl Carbonate as Sustainable Solvent

A simple and direct palladium‐catalyzed aminocarbonylation of 5‐iodo‐1,2,3‐triazoles backbone for the incorporation of an amide functional group is presented. The approach is based on the palladium catalyzed carbonylative coupling reaction of iodo‐triazole with different amines employing formic acid and sulfuric acid as CO source (Morgan's reaction) to provide the 1,2,3‐triazole‐5‐carboxamides in good to excellent yields. The important features of this methodology include short reaction time, high yields, the use of dimethyl carbonate as a sustainable solvent, and the use of efficient alternative source of carbon monoxide, avoiding pressurized cylinder. The methodology described herein for the synthesis of 1,4,5‐trisubstituted 1,2,3‐triazole‐5‐carboxamides, can offers an alternative path for functionalization of other heterocycles.

The Design and Experimental Development of Air Scanning Using a Sniffer Quadcopter.

This study presents a detailed analysis of an air monitoring development system using quadcopters. The data collecting method is based on gas dispersion investigation to pinpoint the gas source location and determine the gas concentration level. Due to its flexibility and low cost, a quadcopter was integrated with air monitoring sensors to collect the required data. The analysis started with the sensor placement on the quadcopter and their correlation with the generated vortex. The reliability and response time of the sensor used determine the duration of the data collection process. The dynamic nature of the environment makes the technique of air monitoring of topmost concern. The pattern method has been adapted to the data collection process in which area scanning was marked using a point of interest or grid point. The experiments were done by manipulating a carbon monoxide (CO) source, with data readings being made in two ways: point source with eight sampling points arranged in a square pattern, and non-point source with 24 sampling points in a grid pattern. The quadcopter collected data while in a hover state with 10 s sampling times at each point. The analysis of variance method (ANOVA) was also used as the statistical algorithm to analyze the vector of gas dispersion. In order to tackle the uncertainty of wind, a bivariate Gaussian kernel analysis was used to get an estimation of the gas source area. The result showed that the grid pattern measurement was useful in obtaining more accurate data of the gas source location and the gas concentration. The vortex field generated by the propeller was used to speed up the accumulation of the gas particles to the sensor. The dynamic nature of the wind caused the gas flow vector to change constantly. Thus, more sampling points were preferred, to improve the accuracy of the gas source location prediction.

Carbon monoxide poisonings in hotels and motels: The problem silently continues.

Carbon monoxide poisoning remains common in the United States. One component of effective prevention involves identification of scenarios in which poisoning occurs to guide development of appropriate interventions. This study was conducted to determine the significance of the problem of carbon monoxide poisoning occurring in US hotels, motels and resorts. This is a population-based case series of guests staying at US hotels, motels, and resorts from 2005 to 2018. Details of incidents and individuals poisoned with carbon monoxide were collected from online searches and professional experience of the authors. Data extracted included number of incidents and individuals poisoned, age of those poisoned, outcomes, source of carbon monoxide, and lodging type. From January 1, 2005 to December 31, 2018, 905 guests were poisoned in 115 identified incidents, including 22 fatalities. Children represented 16% of those poisoned and 27% of fatalities. Type of lodgings were hotels, motels, and resorts of all classes and located in a majority of states. Most poisonings were caused by natural gas fueled appliances and could likely have been prevented by an in-room carbon monoxide alarm. To reduce morbidity and mortality from unintentional CO poisoning in lodging facilities, government should mandate installation of in-room CO alarms, similar to the current requirement for smoke alarms.

Development and Evaluation of a Theory-Based Approach to Reducing Carbon Monoxide (CO) Morbidity and Mortality: The CO Blitz Model

ABSTRACTCarbon monoxide (CO) poisoning is preventable yet remains the most common cause of U.S. non-drug poisoning. The purpose of this non-experimental study was to develop and evaluate the theory-based CO Blitz Model. Events targeted five SC communities; volunteers provided education while local firefighters installed CO alarms. At the 4–6-month follow-up evaluation, all homes still had a functioning CO alarm; most recipients could name CO sources in their homes (78%) and what to do if the alarm sounded (90%). The theory-driven process evaluation revealed the CO Blitz Model was tailorable and effective in addressing unique community resources and needs.

Identification and Statistical Analysis of Impulse-Like Patterns of Carbon Monoxide Variation in Deep Underground Mines Associated with the Blasting Procedure

The quality of the air in underground mines is a challenging issue due to many factors, such as technological processes related to the work of miners (blasting, air conditioning, and ventilation), gas release by the rock mass and geometry of mine corridors. However, to allow miners to start their work, it is crucial to determine the quality of the air. One of the most critical parameters of the air quality is the carbon monoxide (CO) concentration. Thus, in this paper, we analyze the time series describing CO concentration. Firstly, the signal segmentation is proposed, then segmented data (daily patterns) is visualized and statistically analyzed. The method for blasting moment localization, with no prior knowledge, has been presented. It has been found that daily patterns differ and CO concentration values reach a safe level at a different time after blasting. The waiting time to achieve the safe level after blasting moment (with a certain probability) has been calculated based on the historical data. The knowledge about the nature of the CO variability and sources of a high CO concentration can be helpful in creating forecasting models, as well as while planning mining activities.

Carbon Monoxide Cycle in the Bohai Sea and the Yellow Sea: Spatial Variability, Sea‐Air Exchange, and Biological Consumption in Autumn

AbstractAs an important trace gas, carbon monoxide (CO) is considered to be mainly released by the ocean into the atmosphere. To further understand the role of the marginal seas for marine CO emission, we investigated sea‐to‐air flux and spatial distribution as well as biological consumption of CO using the Yellow and Bohai Seas as research objects. In the surface water, CO concentrations varied largely between 0.109 and 6.26 nmol/L. Strong vertical and diurnal variabilities were also observed, which could be attributed to the sunlight‐induced photochemical production of CO at different sampling time and depth. The atmospheric CO mixing ratios generally decreased from the coast to the open ocean, possibly due to the influence of anthropogenic activity. Relative to atmospheric CO, the concentrations of CO were mostly supersaturated in the surface water, suggesting that both the Bohai and the Yellow Seas were significant CO source in the atmosphere. Average sea‐to‐air flux of CO was about 1.76 μmol · m‐2 · day‐1, which largely depended on the saturation factor and wind speed. As an important removal pathway, microbial consumption of CO exhibited the first order kinetics. The rapid turnover of CO (3.2−9.6 hr) indicated that microbial metabolism was the major CO consumer in the surface waters that could significantly regulate the emission of CO to the atmosphere. Overall, this study improved our understanding of the biogeochemical CO cycling in marginal seas as well as in coastal regions.

Non-Fire Related Carbon Monoxide Poisoning in Sichuan, China: A 9-Year Study (2008-2016)

Carbon monoxide (CO) poisoning is one of the most important intoxications in the modern world. This study aimed to identify the characteristics of CO poisoning deaths in Sichuan province in the west of China. Data on fatal non-fire-related carbon monoxide poisoning in Sichuan from 2008 to 2016 were obtained from the Department of Forensic Analytical Toxicology of Sichuan University and were analyzed by the month and year of registration of death, sex, age group, manner of death, source of CO, and location of CO exposure. Comparing with the previous studies carried out in Wuhan and Shanghai to identify the regional differences of CO poisoning in China. A total of 165 non-fire related CO poisoning cases including 237 victims were recorded. Over 90% of the victims died from accidental poisoning. Non-fire related CO poisoning occurred more frequently in winter months and was most prevalent in individuals aged between 18 and 60 yr old. Showering gas accident and coal or charcoal burning was found to be the major source of CO in accident and in suicide cases, respectively. Furthermore, significant regional differences of CO poisoning have been detected in the manner of death and the source of CO. These findings will be valuable in the targeted prevention of non-fire related CO poisoning in China.

Impact of CO generation during the melting process on carbon concentration in Czochralski silicon

A new carbon contamination model in which carbon monoxide (CO) generated by the chemical reaction between H2O and graphite components during the heating stage can react with the solid-state silicon feedstock was proposed. The influence of CO on carbon concentration during the heating stage in a laboratory-scale Czochralski furnace was investigated using a quadrupole mass spectrometer. A strong peak of CO and H2O partial pressure was observed before the silicon feedstock began to melt. We believe that the purge tube is a major source of CO during the heating stage because carbon contamination of the order of 1016 occurred in the silicon melt by CO generated from the purge tube. Furthermore, we discussed the impact of the SiC film formed on the surface of the silicon feedstock on carbon contamination.

Resveratrol protects UVB‐irradiated keratinocytes by upregulating HO‐1 expression and improving mitochondrial function via endogenous CO signaling

Excessive exposure to ultraviolet (UV) radiation has been reported to promote uncontrolled reactive oxygen species (ROS) production, particularly in the mitochondria, and thus implicated in the prevalence of skin injuries. Considering the antioxidative effect of resveratrol (RES) in reducing UV‐induced ROS production in human keratinocytes (HaCaT cells) and the role of carbon monoxide (CO) in regulating oxidative stress, we hypothesized that RES may promote cellular antioxidant response by activating heme oxygenase‐1 (HO‐1) which can generate its enzymatic product, CO, in UVB‐irradiated keratinocytes. To test our hypothesis, we treated HaCaT cells with CO‐releasing molecule 2 (CORM‐2) (source of CO) and RES either independently or in combination and irradiated the cells with UVB. Co‐treatment of CO with RES upregulated HO‐1 expression and subsequently reduced intracellular ROS in response to UV irradiation. Moreover, UVB treatment alone induced mitochondrial biogenesis, but treatment with CO and RES did not increase it further. With UVB treatment, RES showed enhanced mitochondrial respiration while CO did not instigate any effect; however, independent or co‐treatment mitigated mitochondrial ROS production. Taken together, our data support the impression that endogenous CO generated from RES‐mediated activation of HO‐1 may play a crucial role in cellular antioxidant response and mitochondrial function.Support or Funding InformationThis work was supported by the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry, and Fisheries (IPET) through the High Value‐Added Food Technology Development Program, funded by the Ministry of Agriculture, Food, and Rural Affairs (Grant No. 116026‐03‐2‐HD020), Republic of Korea.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Building and indoor environmental quality assessment of Nigerian primary schools: A pilot study

A total of 15 classrooms went through on-site assessments/inspections, including measurements of temperature (T), and concentrations of carbon monoxide (CO) and carbon dioxide (CO2 ). In addition, the level of surface biocontamination/cleaning effectiveness was assessed by measuring adenosine triphosphate (ATP) levels on students' desks. Based on the data, the quality of facilities in the buildings was low. Classroom occupancy exceeded ASHRAE 50 person/100m2 standard in all cases indicating overcrowding. However, concentrations of CO2 remained below 1000ppm in most classrooms. On the other hand, indoor T was above the recommended levels for thermal comfort in all classrooms. Maximum indoor CO was 6ppm. Median ATP concentrations on the desk tops were moderately high in all schools. The use of open incinerators and power generator sets near classrooms, which was suspected to be the main source of CO, should be discouraged. Improved hygiene could be achieved by providing the students access to functioning bathroom facilities and cafeteria, and by effective cleaning of high contact surfaces such as desks. Although ventilation seems adequate based on CO2 concentrations, thermal comfort was not attained especially in the afternoon during extreme sunlight. Therefore, installing passive and/or mechanical cooling systems should be considered in this regard.