In the present work, we have characterized in detail the chemical structures of secondary organic aerosol (SOA) components that were generated in a smog chamber and result from the photooxidation of isoprene under high-NO(x) conditions typical for a polluted atmosphere. Isoprene high-NO(x) SOA contains 2-methylglyceric acid (2-MG) and oligoester derivatives thereof. Trimethylsilylation, in combination with capillary gas chromatography (GC)/ion trap mass spectrometry (MS) and detailed interpretation of the MS data, allowed structural characterization the polar oxygenated compounds present in isoprene SOA up to 2-MG trimers. GC separation was achieved between 2-MG linear and branched dimers or trimers, as well as between the 2-MG linear dimer and isomeric mono-acetate derivatives thereof. The electron ionization (EI) spectra of the trimethylsilyl derivatives contain a wealth of structural information, including information about the molecular weight (MW), oligoester linkages, terminal carboxylic and hydroxymethyl groups, and esterification sites. Only part of this information can be achieved with a soft ionization technique such as electrospray (ESI) in combination with collision-induced dissociation (CID). The methane chemical ionization (CI) data were used to obtain supporting MW information. Interesting EI spectral differences were observed between the trimethylsilyl derivatives of 2-MG linear and branched dimers or trimers and between 2-MG linear dimer mono-acetate isomers.
A summer field campaign was conducted at the forested background site of K-puszta in Hungary. The main aim was to assess the contribution of terpene-derived particulate organic compounds to the PM 2.5 organic carbon (OC) and of the secondary organic carbon (SOC) from α-pinene to the OC. The study lasted from 24 May to 29 June 2006; the first half the weather was cold, while the second half was warm. Separate daytime and night-time PM 2.5 samples were collected with a high-volume sampler and the samples were analysed by several analytical techniques, including ion chromatography (IC) and liquid chromatography-mass spectrometry (LC/MS). The latter technique was used for measuring the terpene-derived species. Ancillary high time resolution measurements of volatile organic compounds (VOCs) were made with proton-transfer reaction-mass spectrometry. The temporal and diurnal variability of the particulate compounds and VOCs and interrelationships were examined. It was found that the monoterpenes and a number of terpene-derived particulate compounds, such as cis-pinic and cis-caric acid, exhibited a strong day/night difference during the warm period, with about 10 times higher levels during the night-time. During the warm period, the IC compounds and LC/MS compounds accounted, on average, for 3.1% and 2.0%, respectively, of the OC, whereas the contribution of SOC from α-pinene to the OC was estimated at a minimum of 7.1%.
W artykule przedstawiono wyniki badań powłok kompozytowych Zn/PTFE wytwarzanych metodą redukcji elektrochemicznej w kąpieli siarczanowo-boranowej o różnej zawartości fazy dyspersyjnej PTFE. Scharakteryzowano budowę wytworzonych powłok oraz oceniono wpływ wbudowania cząstek PTFE na mikrotwardość wytworzonych powłok kompozytowych Zn/PTFE. Wytworzone powłoki charakteryzują się zwartą, jednolitą budową i dobrym połączeniem ze stalowym podłożem. Wbudowanie cząstek PTFE w cynkową osnowę ma wpływ na strukturę i morfologię wytworzonych powłok kompozytowych, powoduje zwiększenie stopnia rozwinięcia powierzchni powłok oraz zwiększenie twardości materiału powłoki w porównaniu z powłoką cynkową.
Celem pracy było wytworzenie powłok niklowych metodą selektywną tamponową o właściwościach ochronnych i dekoracyjnych oraz zoptymalizowanie warunków osadzania. Określono wpływ czasu trwania procesu oraz stosowanego napięcia osadzania na grubość wytworzonych powłok. Badano strukturę przekrojów poprzecznych, morfologię powierzchni, chropowatość i mikrotwardość powłok niklowych. Przeprowadzone badania pozwoliły wytypować najbardziej optymalne parametry procesu osadzania. Opracowano skład roztworu do selektywnego tamponowego osadzania powłok niklowych.
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