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Atmospheric composition

Jean-Paul Lange
When investigating a new catalytic reaction, scientists may wonder if the crude reaction product can be easily separated and purified. We present here a new concept-distillation resistance-to assess the potential of distillation as a purification technique and to guide catalyst formulation or operation at the very early stage of the research. Distillation resistance, which has been developed from the analysis of 15 industrial distillation trains, can be quickly calculated with knowledge of only the product composition and atmospheric boiling points of the components...
October 20, 2016: ChemSusChem
Jonguk Park, Tomoaki Ichijo, Masao Nasu, Nobuyasu Yamaguchi
Atmospheric bacterial dispersion with aeolian dust has been reported to have a potential impact on public health and ecosystems. Asian dust is a major aeolian event that results in an estimated 4 million tons of Asian dust particles falling in Japan annually, 3,000-5,000 km away from their source regions. However, most studies have only investigated the effects of Asian dust during dust seasons. Therefore, in this study, outdoor bacterial abundance and community composition were determined by 16S rRNA quantitative PCR and amplicon sequencing, respectively, and compared on Asian and non-Asian dust days (2013-2015; 44 samples over four seasons)...
October 20, 2016: Scientific Reports
Andrew N Gherlenda, Ben D Moore, Anthony M Haigh, Scott N Johnson, Markus Riegler
BACKGROUND: Climate change factors such as elevated atmospheric carbon dioxide concentrations (e[CO2]) and altered rainfall patterns can alter leaf composition and phenology. This may subsequently impact insect herbivory. In sclerophyllous forests insects have developed strategies, such as preferentially feeding on new leaf growth, to overcome physical or foliar nitrogen constraints, and this may shift under climate change. Few studies of insect herbivory at elevated [CO2] have occurred under field conditions and none on mature evergreen trees in a naturally established forest, yet estimates for leaf area loss due to herbivory are required in order to allow accurate predictions of plant productivity in future climates...
October 19, 2016: BMC Ecology
Sheng Xu, Gordon T Cook, Alan J Cresswell, Elaine Dunbar, Stewart P H T Freeman, Xiaolin Hou, Helen Kinch, Philip Naysmith, David W C Sanderson, Luyuan Zhang
Japanese cedar leaves from Iwaki, Fukushima were analyzed for carbon, cesium and iodine isotopic compositions before and after the 2011 nuclear accident. The Δ(14)C values reflect ambient atmospheric (14)C concentrations during the year the leaves were sampled/defoliated, and also previous year(s). The elevated (129)I and (134,137)Cs concentrations are attributed to direct exposure to the radioactive fallout for the pre-fallout-expended leaves and to internal translocation from older parts of the tree for post-fallout-expended leaves...
2016: Journal of Radioanalytical and Nuclear Chemistry
Asma Asemaninejad, R Greg Thorn, Zoë Lindo
Peatlands play an important role in global climate change through sequestration of atmospheric CO2. Climate-driven changes in the structure of fungal communities in boreal peatlands that favor saprotrophic fungi can substantially impact carbon dynamics and nutrient cycling in these crucial ecosystems. In a mesocosm study using a full factorial design, 100 intact peat monoliths, complete with living Sphagnum and above-ground vascular vegetation, were subjected to three climate change variables (increased temperature, reduced water table, and elevated CO2 concentrations)...
October 15, 2016: Microbial Ecology
Zhifeng Bai, Diego Edison Cristancho, Aaron A Rachford, Amy L Reder, Alexander Williamson, Adam L Grzesiak
We report a two-component label system comprising a chlorite-containing polymer film and an acid-containing polymer film that can release antimicrobial ClO2 gas upon adhering the two films together to enable a reaction of the chlorite and acid under moisture exposure. The chlorite-containing film comprises a commercial acrylate-based pressure sensitive adhesive polymer impregnated with sodium chlorite. The acid-containing film comprises a commercial polyvinyl alcohol polymer loaded with tartaric acid. Both of the films were prepared on low ClO2-absorbing substrate films from stable aqueous systems of the polymers with high reagent loading...
October 13, 2016: Journal of Agricultural and Food Chemistry
Thalita Dallapícula Ramos, Ricardo J Cassella, Miguel de la Guardia, Agustín Pastor, Francesc A Esteve-Turrillas
The versatile, easy, and rapid atmospheric monitor (VERAM), a passive sampler device widely used for air monitoring, was evaluated as passive sampler for the determination of 23 pesticides in water. Gas chromatography with mass spectrometry detection was employed for determination of pesticides after microwave-assisted-extraction and specific clean-up of deployed samplers. The proposed methodology reached method detection levels from 2 to 10 ng pesticide per sampler. Sampling rate (Rs) was determined for every pesticide from an uptake isotherm study performed at three different concentration levels (50, 125, and 250 ng L(-1))...
October 12, 2016: Analytical and Bioanalytical Chemistry
Ivan Kourtchev, Chiara Giorio, Antti Manninen, Eoin Wilson, Brendan Mahon, Juho Aalto, Maija Kajos, Dean Venables, Taina Ruuskanen, Janne Levula, Matti Loponen, Sarah Connors, Neil Harris, Defeng Zhao, Astrid Kiendler-Scharr, Thomas Mentel, Yinon Rudich, Mattias Hallquist, Jean-Francois Doussin, Willy Maenhaut, Jaana Bäck, Tuukka Petäjä, John Wenger, Markku Kulmala, Markus Kalberer
Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples...
October 13, 2016: Scientific Reports
Y Chen, Kevin K Lehmann, Y Peng, L M Pratt, J R White, S B Cadieux, B Sherwood Lollar, G Lacrampe-Couloume, T C Onstott
In this study, near-infrared continuous wave cavity ring-down spectroscopy was applied to the measurement of the δ(2)H of methane (CH4). The cavity ring-down spectrometer (CRDS) system consisted of multiple DFB laser diodes to optimize selection of spectral line pairs. By rapidly switching measurements between spectral line peaks and the baseline regions, the long-term instrumental drift was minimized, substantially increasing measurement precision. The CRDS system coupled with a cryogenic pre-concentrator measured the δ(2)H of terrestrial atmospheric CH4 from 3 standard liters of air with a precision of ±1...
October 2016: Astrobiology
Martin Civiš, Martin Ferus, Antonín Knížek, Petr Kubelík, Michal Kamas, Patrik Španěl, Ksenia Dryahina, Violetta Shestivska, Libor Juha, Petr Skřehot, Vojtěch Laitl, Svatopluk Civiš
Large-scale plasma was created in gas mixtures containing methane using high-power laser-induced dielectric breakdown (LIDB). The composition of the mixtures corresponded to a cometary and/or meteoritic impact into the early atmosphere of either Titan or Earth. A multiple-centimeter-sized fireball was created by focusing a single 100 J, 450 ps near-infrared laser pulse into the center of a 15 L gas cell. The excited reaction intermediates formed during the various stages of the LIDB plasma chemical evolution were investigated using optical emission spectroscopy (OES) with temporal resolution...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
Lars H Jepsen, Peikun Wang, Guotao Wu, Zhitao Xiong, Flemming Besenbacher, Ping Chen, Torben R Jensen
Sodium amide, NaNH2, has recently been shown to be a useful catalyst to decompose NH3 into H2 and N2, however, sodium hydroxide is omnipresent and commercially available NaNH2 usually contains impurities of NaOH (<2%). The thermal decomposition of NaNH2 and NaNH2-NaOH composites is systematically investigated and discussed. NaNH2 is partially dissolved in NaOH at T > 100 °C, forming a non-stoichiometric solid solution of Na(OH)1-x(NH2)x (0 < x < ∼0.30), which crystallizes in an orthorhombic unit cell with the space group P212121 determined by synchrotron powder X-ray diffraction...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Maria Neve Ombra, Autilia Cozzolino, Filomena Nazzaro, Antonio d'Acierno, Patrizio Tremonte, Raffaele Coppola, Florinda Fratianni
Two Brassicaceae (Eruca sativa, Brassica oleracea var. sabauda) were stored in air and under a modified atmosphere for several days after their expiry date and then analyzed. The polyphenol content and composition, as well as the antioxidant activity of the extracts, were assessed, compared to the fresh products. Antimicrobial properties on tester strains (Bacillus cereus, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) and in vitro anti-proliferative activity were evaluated. The cabbage extracts exhibited antimicrobial activity mainly on the ninth day after the expiry date and retained significant inhibitory effects against colon carcinoma (CaCo-2) cells...
March 1, 2017: Food Chemistry
Xiaoyang Pan, Xuxing Chen, Zhiguo Yi
Because of the high C-H bond energy as well as the non-polar feature of CH4 molecules, oxidation of methane under mild conditions remains a challenging task for both C1 utilization and atmospheric environmental cleansing. Here we report that by using a sol-gel method SrCO3 decorated SrTiO3 nanocatalysts (SrTiO3-S) with an average particle size of ∼25 nm can be readily prepared, which surprisingly show efficient performance for photocatalytic oxidation of methane with the activity close to fourfold of P25, a benchmark photocatalyst...
September 15, 2016: Physical Chemistry Chemical Physics: PCCP
Alexander L Vogel, Johannes Schneider, Christina Müller-Tautges, Thomas Klimach, Thorsten Hoffmann
Atmospheric oxidation of volatile organic compounds (VOCs) yields a large number of different organic molecules which comprise a wide range of volatility. Depending on their volatility, they can be involved in new particle formation and particle growth, thus affecting the number concentration of cloud condensation nuclei in the atmosphere. Here, we identified oxidation products of VOCs in the particle phase during a field study at a rural mountaintop station in central Germany. We used atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) and aerosol mass spectrometry for time-resolved measurements of organic species and of the total organic aerosol (OA) mass in the size range of 0...
October 6, 2016: Environmental Science & Technology
Alexander L Vogel, Johannes Schneider, Christina Müller-Tautges, Gavin J Phillips, Mira L Pöhlker, Diana Rose, Christoph Zuth, Ulla Makkonen, Hannele Hakola, John N Crowley, Meinrat O Andreae, Ulrich Pöschl, Thorsten Hoffmann
Aerosol hygroscopic properties were linked to its chemical composition by using complementary online mass spectrometric techniques in a comprehensive chemical characterization study at a rural mountaintop station in central Germany in August 2012. In particular, atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) provided measurements of organic acids, organosulfates, and nitrooxy-organosulfates in the particle phase at 1 min time resolution. Offline analysis of filter samples enabled us to determine the molecular composition of signals appearing in the online (-)APCI-MS spectra...
October 6, 2016: Environmental Science & Technology
Birmania Heredia Rivera, Martín Gerardo Rodriguez
Particulate matter accumulated on car engine air-filters (CAFs) was examined in order to investigate the potential use of these devices as efficient samplers for collecting street level air that people are exposed to. The morphology, microstructure, and chemical composition of a variety of particles were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The particulate matter accumulated by the CAFs was studied in two categories; the first was of removed particles by friction, and the second consisted of particles retained on the filters...
October 1, 2016: International Journal of Environmental Research and Public Health
Peng Lin, Paige K Aiona, Ying Li, Manabu Shiraiwa, Julia Laskin, Sergey A Nizkorodov, Alexander Laskin
Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate the molecular composition of freshly-emitted biomass burning organic aerosol (BBOA) samples collected during test burns of sawgrass, peat, ponderosa pine, and black spruce. We demonstrate that both the BrC absorption and the chemical composition of light-absorbing compounds depend significantly on the type of biomass fuels. Common BrC chromophores in the selected BBOA samples include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, and polyphenols spanning a wide range of molecular weights, structures, and light absorption properties...
October 5, 2016: Environmental Science & Technology
Xiao Wang, Ranran Wang, Haitao Zhai, Xi Shen, Tao Wang, Liangjing Shi, Richeng Yu, Jing Sun
Cu nanowires (Copper nanowires) have attracted lots of attention recently due to their potential applications in transparent electrodes, SERS sensors and solar cells. However, as the surface composition and morphology of Cu nanowires severely influence the performance of the devices based on them, facial surface modification methods need to be developed. Herein, we propose a room-temperature, time-saving aqueous solution method, which can simultaneously clean the surface of copper nanowires and decorate them with Ag nanoparticles at room temperature without any atmospheric control...
October 5, 2016: ACS Applied Materials & Interfaces
Valerie J Alstadt, James David Kubicki, Miriam Arak Freedman
Mineral dust is prevalent in the atmosphere due to emissions from natural and anthropogenic sources. As mineral dust particles undergo long distance transport, they are exposed to trace gases and water vapor. We have characterized the interactions of acetic acid on kaolinite using Diffuse Reflectance Infrared Fourier Transform Spectroscopy and molecular modeling to determine the chemisorbed species present. After the addition of acetic acid, gas phase water was introduced to explore how water vapor competes with acetic acid for surface sites...
October 5, 2016: Journal of Physical Chemistry. A
J K Böhlke, Stanley J Mroczkowski, Neil C Sturchio, Linnea J Heraty, Kent W Richman, Donald B Sullivan, Kris N Griffith, Baohua Gu, Paul B Hatzinger
RATIONALE: Perchlorate (ClO4(-) ) is a common trace constituent of water, soils, and plants; it has both natural and synthetic sources and is subject to biodegradation. The stable isotope ratios of Cl and O provide three independent quantities for ClO4(-) source attribution and natural attenuation studies: δ(37) Cl, δ(18) O, and δ(17) O (or Δ(17) O or (17) Δ) values. Documented reference materials, calibration schemes, methods, and interferences will improve the reliability of such studies...
October 3, 2016: Rapid Communications in Mass Spectrometry: RCM
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