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Marcin Procek, Kinga Kepska, Agnieszka Stolarczyk
The detection and concentration measurements of low concentrations of nitrogen dioxide (NO₂) are important because of its negative effects on human health and its application in many fields of industry and safety systems. In our approach, conducting graft copolymers based on the poly(3-hexylthiophene) (P3HT) conducting polymer and other side-chains, polyethylene glycol (PEG) and dodec-1-en, grafted on a poly(methylhydrosiloxane) backbone, were investigated. The grafts containing PEG (PEGSil) and dodec-1-en (DodecSil) in two variants, namely, fractions with shorter (hexane fraction -H) and longer (chloroform fraction -CH) side-chains of P3HT, were tested as receptor structures in NO₂ gas sensors...
March 20, 2018: Sensors
S K Schmidt, E M S Gendron, K Vincent, A J Solon, P Sommers, Z R Schubert, L Vimercati, D L Porazinska, J L Darcy, P Sowell
Here we describe recent breakthroughs in our understanding of microbial life in dry volcanic tephra ("soil") that covers much of the surface area of the highest elevation volcanoes on Earth. Dry tephra above 6000 m.a.s.l. is perhaps the best Earth analog for the surface of Mars because these "soils" are acidic, extremely oligotrophic, exposed to a thin atmosphere, high UV fluxes, and extreme temperature fluctuations across the freezing point. The simple microbial communities found in these extreme sites have among the lowest alpha diversity of any known earthly ecosystem and contain bacteria and eukaryotes that are uniquely adapted to these extreme conditions...
March 20, 2018: Antonie Van Leeuwenhoek
D J Medeiros, M A Blitz, P W Seakins
Ab initio theory has been used to identify the pre-reaction complex in the atmospherically important reaction between OH + SO2, (R1), where the binding energy of the pre-reaction complex was determined to be 7.2 kJ mol-1. Using reaction rate theory, implemented with the master equation package MESMER, the effects of this complex on the kinetics of R1 at temperatures above 250 K have been investigated. From simulations and fitting to the experimental kinetic data, it is clear that the influence of this pre-reaction complex is negligible and that the kinetics are controlled by the inner transition-state that leads to the product, HOSO2...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Toshinobu Korenaga, Kaoru Nitatori, Hiroki Muraoka, Satoshi Ogawa, Kazuaki Shimada
The oxidative homo-coupling reaction of Grignard reagents in the presence of atmospheric oxygen molecules proceeded in the presence of heptafluorotolyl-substituted perfluorocyclopentadienyl radical. The turnover number (TON) was over 30 for the coupling reactions of PhMgBr to give biphenyl. The organocatalyst could couple thienylmagnesium compounds to give bithiophene derivatives in up to 94% yield. Furthermore, gram-scale synthesis of 6,6'-dimethoxybiphenyl-2,2'-diyl-bis(phosphonic acid diethyl ester) was demonstrated...
March 20, 2018: Journal of Organic Chemistry
Dunia E Santiago, Luisa M Pastrana-Martínez, Elisenda Pulido-Melián, Javier Araña, Joaquim L Faria, Adrián M T Silva, Óscar González-Díaz, José M Doña-Rodríguez
Magnetite (Fe3 O4 ), a core-shell material (SiO2 @Fe3 O4 ), and reduced graphene oxide-Fe3 O4 (referred as rGO-MN) were used as supports of a specific highly active TiO2 photocatalyst. Thermal treatments at 200 or 450 °C, different atmospheres (air or N2 ), and TiO2 :support weight ratios (1.0, 1.5, or 2.0) were investigated. X-ray diffractograms revealed that magnetite is not oxidized to hematite when the core-shell SiO2 @Fe3 O4 material-or a N2 atmosphere (instead of air) in the thermal treatment-was employed to prepare the TiO2 -based catalysts (the magnetic properties being preserved)...
March 2, 2018: Environmental Science and Pollution Research International
Lamri Naidja, Hocine Ali-Khodja, Salah Khardi
In order to assess the significance of PM in ambient air, it is necessary to evaluate their physical and chemical characteristics as well as identify their major emission sources. On a global scale, particulate matter in the atmosphere arises mainly from the combustion process of motorized vehicles, but natural sources are still considered as the major contributors. In Africa, PM emissions differ from those in developed countries; human activities such as biomass burning in households, poor household waste management, and the high number of diesel-powered vehicles are the predominant anthropogenic sources...
March 19, 2018: Environmental Science and Pollution Research International
Heng Guo, Xiao-Ning Zhang, Jian Chen, He-Ping Li, Kostya Ken Ostrikov
Non-equilibrium is one of the important features of an atmospheric gas discharge plasma. It involves complicated physical-chemical processes and plays a key role in various actual plasma processing. In this report, a novel complete non-equilibrium model is developed to reveal the non-equilibrium synergistic effects for the atmospheric-pressure low-temperature plasmas (AP-LTPs). It combines a thermal-chemical non-equilibrium fluid model for the quasi-neutral plasma region and a simplified sheath model for the electrode sheath region...
March 19, 2018: Scientific Reports
A C Ruiz-Fernández, V Carnero-Bravo, J A Sanchez-Cabeza, L H Pérez-Bernal, O A Amaya-Monterrosa, S Bojórquez-Sánchez, P G López-Mendoza, J G Cardoso-Mohedano, R B Dunbar, D A Mucciarone, A J Marmolejo-Rodríguez
Coastal vegetated habitats can be important sinks of organic carbon (Corg ) and mitigate global warming by sequestering significant quantities of atmospheric CO2 and storing sedimentary Corg for long periods, although their Corg burial and storage capacity may be affected by on-going sea level rise and human intervention. Geochemical data from published210 Pb-dated sediment cores, collected from low-energy microtidal coastal wetlands in El Salvador (Jiquilisco Bay) and in Mexico (Salada Lagoon; Estero de Urias Lagoon; Sian Ka'an Biosphere Reserve) were revisited to assess temporal changes (within the last 100years) of Corg concentrations, storage and burial rates in tropical salt marshes under the influence of sea level rise and contrasting anthropization degree...
March 13, 2018: Science of the Total Environment
Diana Meza-Figueroa, Belem González-Grijalva, Francisco Romero, Joaquin Ruiz, Martín Pedroza-Montero, Carlos Ibañez-Del Rivero, Mónica Acosta-Elías, Lucas Ochoa-Landin, Sofía Navarro-Espinoza
The environmental fate of lead derived from traffic paint has been poorly studied in developing countries, mainly in arid zones. For this purpose, a developing city located in the Sonoran desert (Hermosillo, Mexico), was chosen to conduct a study. In this paper the lead chromate (crocoite) sources in atmospheric dust were addressed using a combination of Raman microspectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and Pb isotope measurements. A high concentration of Pb and Cr as micro- and nanostructured pigments of crocoite is reported in yellow traffic paint (n=80), road dust (n=146), settled dust in roofs (n=21), and atmospheric dust (n=20) from a developing city located in the Sonoran Desert...
March 7, 2018: Science of the Total Environment
João Henrique F Amaral, Alberto V Borges, John M Melack, Hugo Sarmento, Pedro M Barbosa, Daniele Kasper, Michaela L de Melo, Daniela De Fex-Wolf, Jonismar S da Silva, Bruce R Forsberg
We investigated plankton metabolism and its influence on carbon dioxide (CO2 ) dynamics in a central Amazon floodplain lake (Janauacá, 3°23' S, 60°18' W) from September 2015 to May 2016, including a period with exceptional drought. We made diel measurements of CO2 emissions to the atmosphere with floating chambers and depth profiles of temperature and CO2 partial pressure (pCO2 ) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism...
March 3, 2018: Science of the Total Environment
Lulu Cui, Rui Li, Yunchen Zhang, Ya Meng, Hongbo Fu, Jianmin Chen
Continuous HONO measurement was conducted to study the formation features of HONO during the haze episodes at Shanghai, China. The HONO concentration ranged from 0.26 to 5.84ppb and averaged at 2.31ppb during the measurement period. The HONO concentration during the haze episode (P1), the haze-fog episode (P2) and the clean period (P3) were 2.80, 2.35 and 1.78ppb, respectively. Heterogeneous conversion of NO2 was the dominate pathway for nocturnal HONO formation, and the heterogeneous conversion efficiency of NO2 to HONO was closely associated with the PM2...
March 1, 2018: Science of the Total Environment
Gerson Fernandino, Carla I Elliff, Iracema R Silva
Climate change effects have the potential of affecting both ocean and atmospheric processes. These changes pose serious threats to the millions of people that live by the coast. Thus, the objective of the present review is to discuss how climate change is altering (and will continue to alter) atmospheric and oceanic processes, what are the main implications of these alterations along the coastline, and which are the ecosystem-based management (EBM) strategies that have been proposed and applied to address these issues...
March 16, 2018: Journal of Environmental Management
Jian Zhong, Irina Nikolova, Xiaoming Cai, A Rob MacKenzie, Roy M Harrison
This study implements a two-box model coupled with ultrafine particle (UFP) multicomponent microphysics for a compartmentalised street canyon. Canyon compartmentalisation can be described parsimoniously by three parameters relating to the features of the canyon and the atmospheric state outside the canyon, i.e. the heterogeneity coefficient, the vortex-to-vortex exchange velocity, and the box height ratio. The quasi-steady solutions for the two compartments represent a balance among emissions, microphysical aerosol dynamics (i...
March 16, 2018: Environmental Pollution
Sung-Wook Yun, Philippe C Baveye, Dong-Hyeon Kim, Dong-Hyeon Kang, Si-Young Lee, Min-Jae Kong, Chan-Gi Park, Hae-Do Kim, Jinkwan Son, Chan Yu
Soil contamination due to atmospheric deposition of metals originating from smelters is a global environmental problem. A common problem associated with this contamination is the discrimination between anthropic and natural contributions to soil metal concentrations: In this context, we investigated the characteristics of soil contamination in the surrounding area of a world class smelter. We attempted to combine several approaches in order to identify sources of metals in soils and to examine contamination characteristics, such as pollution level, range, and spatial distribution...
March 16, 2018: Environmental Pollution
Markus Köhler, Patrick Oßwald, Dominik Krueger, Ryan Whitside
This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This flexible tool offers a detailed observation of chemical gas-phase kinetics in reacting flows under well-controlled conditions. The vast range of operating conditions available in a laminar flow reactor enables access to extraordinary combustion applications that are typically not achievable by flame experiments. These include rich conditions at high temperatures relevant for gasification processes, the peroxy chemistry governing the low temperature oxidation regime or investigations of complex technical fuels...
February 19, 2018: Journal of Visualized Experiments: JoVE
Piran R Kidambi, Dhanushkodi D Mariappan, Nicholas T Dee, Andrey Vyatskikh, Sui Zhang, Rohit Karnik, A John Hart
Scalable, cost-effective synthesis and integration of graphene is imperative to realize large-area applications such as nanoporous atomically thin membranes (NATMs). Here, we report a scalable route to the production of NATMs via high-speed, continuous synthesis of large-area graphene by roll-to-roll chemical vapor deposition (CVD), combined with casting of a hierarchically porous polymer support. To begin, we designed and built a two zone roll-to-roll graphene CVD reactor, which sequentially exposes the moving foil substrate to annealing and growth atmospheres, with a sharp, isothermal transition between the zones...
March 19, 2018: ACS Applied Materials & Interfaces
A Travaglini, S Masieri, C Cavaliere, M A Brighetti
Allergies caused by inhalant allergens, particularly pollens, are steadily increasing in urban centers. It is known that atmospheric pollution is strongly related to the inflammatory disease of the upper and lower airways but it is equally important in the development of sensitization towards pollens. Particulate Matter (PM), sulfur dioxide (SO2) and nitrogen dioxide (NO2) have an enhancement function on the persistence of pollens in the air, increasing the concentration and duration of pollinosis. It is therefore essential to use air quality control methods in urban centers to monitor the presence of pollen and fine dust that can drive the doctor and the patient to improve prevention, a step of primary importance in the treatment of allergies...
January 2018: Journal of Biological Regulators and Homeostatic Agents
Jose L Roscales, Juan Muñoz-Arnanz, María Ros, Alba Vicente, Laura Barrios, Begoña Jiménez
The Stockholm Convention (SC) on Persistent Organic Pollutants (POPs) calls for the Parties' effectiveness evaluation of those measures taken to meet the reduction and eventual elimination of POPs from the environment. With that goal, air concentrations of different POP families have been measured uninterruptedly since 2008 under the Spanish Monitoring Program (SMP) by means of passive air sampling. This work focuses on data for polybrominated diphenyl ethers (PBDEs) determined in a total of 321 samples collected seasonally each year in 5 urban and 7 background sites...
March 14, 2018: Science of the Total Environment
Triantafyllia Vouzara, Garyfallia Dimosiari, Elisabeth A Koulaouzidou, Nikolaos Economides
INTRODUCTION: Resin sealers with biocompatible and bioactive additives have been used in clinical practice. Recently, a calcium silicate root canal sealer was introduced under the name BioRoot RCS (Septodont, Saint Maur-des-Fossés, France). The aim of this study was to evaluate the effects of BioRoot RCS on cell survival and proliferation of cultured cells in parallel with an epoxy resin sealer with calcium phosphate and calcium oxide and a salicylate resin sealer with mineral trioxide aggregate filler...
March 14, 2018: Journal of Endodontics
T C McDonnell, S Belyazid, T J Sullivan, M Bell, C Clark, T Blett, T Evans, W Cass, A Hyduke, H Sverdrup
Ecological effects of atmospheric nitrogen (N) and sulfur (S) deposition on two hardwood forest sites in the eastern United States were simulated in the context of a changing climate using the dynamic coupled biogeochemical/ecological model chain ForSAFE-Veg. The sites are a mixed oak forest in Shenandoah National Park, Virginia (Piney River) and a mixed oak-sugar maple forest in Great Smoky Mountains National Park, Tennessee (Cosby Creek). The sites have received relatively high levels of both S and N deposition and the climate has warmed over the past half century or longer...
March 14, 2018: Environmental Pollution
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