Characterization of polar organosulfates in secondary organic aerosol from the unsaturated aldehydes 2-E-pentenal, 2-E-hexenal, and 3-Z-hexenal

We show in the present study that the unsaturated aldehydes 2-E-pentenal, 2-E-hexenal, and 3-Z-hexenal are biogenic volatile organic compound (BVOC) precursors for polar organosulfates with molecular weights (MWs) 230 and 214, which are also present in ambient fine aerosol from a forested site, i.e., K-puszta, Hungary. These results complement those obtained in a previous study showing that the green leaf aldehyde 3-Z-hexenal serves as a precursor for MW 226 organosulfates. Thus, in addition to isoprene, the green leaf volatiles (GLVs) 2-E-hexenal and 3-Z-hexenal, emitted due to plant stress (mechanical wounding or insect attack), and 2-E-pentenal, a photolysis product of 3-Z-hexenal, should be taken into account for secondary organic aerosol and organosulfate formation. Polar organosulfates are of climatic relevance because of their hydrophilic properties and cloud effects. Extensive use was made of organic mass spectrometry (MS) and detailed interpretation of MS data (i.e., ion trap MS and accurate mass measurements) to elucidate the chemical structures of the MW 230, 214 and 170 organosulfates formed from 2-E-pentenal and indirectly from 2-E-hexenal and 3-Z-hexenal. In addition, quantum chemical calculations were performed to explain the different mass spectral behavior of 2,3-dihydroxypentanoic acid sulfate derivatives, where only the isomer with the sulfate group at C-3 results in the loss of SO3. The MW 214 organosulfates formed from 2-E-pentenal are explained by epoxidation of the double bond in the gas phase and sulfation of the epoxy group with sulfuric acid in the particle phase through the same pathway as that proposed for 3-sulfooxy-2-hydroxy-2-methylpropanoic acid from the isoprene-related alpha,beta-unsaturated aldehyde methacrolein in previous work (Lin et al., 2013). The MW 230 organosulfates formed from 2-E-pentenal are tentatively explained by a novel pathway, which bears features of the latter pathway but introduces an additional hydroxyl group at the C-4 position. Evidence is also presented that the MW 214 positional isomer, 2-sulfooxy-3-hydroxypentanoic acid, is unstable and decarboxylates, giving rise to 1-sulfooxy-2-hydroxybutane, a MW 170 organosulfate. Furthermore, evidence is obtained that lactic acid sulfate is generated from 2-E-pentenal. This chemistry could be important on a regional and local scale where GLV emissions such as from grasses and cereal crops are substantial

Chemical composition of isoprene SOA under acidic and non-acidic conditions: effect of relative humidity

The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies; however, few measurements have been conducted on individual aerosol compounds. The focus of this study has been the examination of the effect of acidity and relative humidity on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of nitrogen oxide (NOx). A detailed characterization of SOA at the molecular level was also investigated. Experiments were conducted in a 14.5&thinsp;m3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from gas chromatography–mass spectrometry of silylated derivatives in electron impact and chemical ionization modes, ultra-high performance liquid chromatography/electrospray ionization/time-of-flight high-resolution mass spectrometry, and collision-induced dissociation in the negative ionization modes, we characterized not only typical isoprene products but also new oxygenated compounds. A series of nitroxy-organosulfates (NOSs) were tentatively identified on the basis of high-resolution mass spectra. Under acidic conditions, the major identified compounds include 2-methyltetrols (2MT), 2-methylglyceric acid (2mGA), and 2MT-OS. Other products identified include epoxydiols, mono- and dicarboxylic acids, other organic sulfates, and nitroxy- and nitrosoxy-OS. The contribution of SOA products from isoprene oxidation to PM2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. Methyltetrols, 2mGA, and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of relative humidity on SOA formation was modest in non-acidic-seed experiments and stronger under acidic seed aerosol. Total secondary organic carbon decreased with increasing relative humidity under both acidic and non-acidic conditions. While the yields of some of the specific organic compounds decreased with increasing relative humidity, others varied in an indeterminate manner from changes in the relative humidity.</p

The modern approach to manufacturing of carbon-rhenium nanocomposites

Purpose The aim of the paper is to present the high-temperature method of producing MWCNTs-Re nanocomposites, the selection of satisfactory production conditions and the presentation of the results of microscopic and spectroscopic studies of nanocomposites produced by this method. Design/methodology/approach Two methods of manufacturing carbon-rhenium nanocomposites were tested: ineffective chemical synthesis and high-temperature reduction using H2, which was proven successful and allowed the production of nanocomposites with the expected properties. The received nanocomposites were investigated using Transmission Electron Microscope (TEM), and Scanning Electron Microscope (SEM), as well as were subjected to spectroscopic examination. Findings The article presents three steps of MWCNTs-Re nanocomposites fabrication using the high-temperature method, functionalization, impregnation and reduction. As part of own work, satisfactory conditions for producing those nanocomposites using a materials science and heuristic analysis were selected. Research limitations/implications The proposed high-temperature method allows to join rhenium nanoparticles with MWCNTs permanently. It is reasonable to test in the future whether the method is also effective for other carbon nanomaterials and/or nanoparticles of other metals. Practical implications MWCNTs-Re nanocomposites can be used as sensors of gases that are harmful to the environment. It was also confirmed that the MWCNTs-Re_4 nanocomposite has catalytic properties. Originality/value The paper presents a modern approach to the manufacturing of MWCNTs-Re nanocomposites, which assumes the use of a high-temperature furnace to heat the material in a hydrogen atmosphere

Microscopic And Spectroscopic Research Of The MWCNTs-Re Nanocomposites

The combination of TEM research and Raman spectroscopy to characterization of MWNTs-Re nanocomposites gives a new notion about the structure and quality of materials obtained. TEM studies indicate that the functionalization method significantly influences the morphology of obtained MWCNTs-Re nanocomposites. Due to the specific spectrum recorded for the MWCNTs they can be distinguished from other forms of carbon, furthermore comparative analysis of the results at different stages of the manufacturing process confirms the covalent modification of the MWCNTs structure

Long-Term Development Perspectives of Selected Groups of Engineering Materials Used in the Automotive Industry/ Długoterminowe Perspektywy Rozwoju Wybranych Grup Materiałów Inżynierskich Stosowanych W Przemyśle Motoryzacyjnym

The purpose of the article is to present the results of comparative quantitative analysis of selected materials (steel, magnesium and aluminium alloys) and manufacturing technologies, to indicate their development outlooks and to present its application opportunities particularly in the automotive industry. Moreover in this article describes the application of the computer-integrated prediction of development for objectivised selection of a material and surface treatment technology, so that product properties can be achieved as are expected by a client. In a broad array of applications of the computer-integrated prediction of development in the field of material engineering, including materials surface engineering, experiment planning can be distinguished, usually including the selection of: a research material, surface treatment technology, construction solution and/or methods to review the final outcome achieved against the anticipated outcome. A material for the planned materials science experiments and its surface treatment technology, the application of which contributes most to meeting the high requirements set by a prospect product used, was selected in this work using a dendrological matrix of technology value. The dendrological matrix falls into to a group of contextual matrices allowing presenting graphically a quantitative assessment of the factor, phenomenon or process investigated while taking into account two analysis factors placed on the X and Y axis of the matrix. An evaluation classifying the three groups of materials analysed, i.e. casting magnesium alloys, casting aluminium alloys, constructional steels and their surface treatment technologies, to the individual quarters of the matrix was made based on the results of own materials science and heuristic experiments supported with a review of the literature. Considering the three groups of materials subjected to an expert assessment using a dendrological matrix being inherent part of materials surface engineering development prediction methods. Aluminium cast alloys has achieved here the best position. It was further demonstrated that laser treatment is a technology with the highest potential and attractiveness in the context of applying aluminium casting alloys for surface treatment. The metallographic examinations carried out give grounds to state that the ceramic powder alloying or feeding process will be carried out successfully in case of the aluminium alloy substrate, the powder particles will be distributed uniformly in the investigated surface layer, and that the particular layers is without cracks and failures and tightly adhere to the cast aluminium material matrix. With regard to the above, dynamic development achieved by exploitation of numerous application and development opportunities, especially strong prospects in the automotive industry, aviation industry, military sector, sport sector and in civil engineering is a recommended by appliance of long-term action strategy.Głównym założeniem artykułu jest przedstawienie wyników opracowanej ilościowej analizy porównawczej wybranych grup materiałów inżynierskich (stali, stopów magnezu i aluminium) oraz technologii ich obróbki, w celu określenia perspektyw rozwoju oraz możliwości zastosowania badanych materiałów w szczególności w przemyśle motoryzacyjnym. Ponadto w artykule opisano zastosowanie analizy komputerowej pozwalającej na prognozowanie dalszego rozwoju opisywanych grup materiałów oraz technologii ich obróbki powierzchniowej, pozwalającej na uzyskanie oczekiwanych przez klienta własności produktu. W szerokim wachlarzu zastosowań komputerowo-zintegrowanej predykcji rozwoju w dziedzinie inżynierii materiałowej, w tym inżynierii powierzchni, wyróżnić można poszczególne stadia planowania eksperymentu, obejmujące zazwyczaj dobór m.in.: materiału do badań, technologii obróbki powierzchniowej materiałów, zastosowanych rozwiązań konstrukcyjnych i/lub metody oceny wyników końcowych oraz ich porównanie z wynikami podlegającymi predykcji. Materiały do badań oraz technologie ich obróbki powierzchniowej, których zastosowanie w szerokim zakresie zaspokaja wysokie wymagania klientów odnosnie aplikacji, zostały wyselekcjonowane przy użyciu matrycy dendrologicznej uwzględniającej założone parametry technologiczne. Matryca dendrologiczna zaliczana jest do grupy macierzy kontekstowych pozwalających na graficzna prezentacje oceny ilościowej danego współczynnika, zjawiska lub badanego procesu, biorąc pod uwagę dwa czynniki analizy umieszczone na osiach X i Y matrycy. Klasyfikacja trzech grup analizowanych materiałów, w tym odlewniczych stopów magnezu, stopów aluminium i stalikonstrukcyjnych oraz technologii ich obróbki powierzchniowej, do poszczególnych ćwiartek matrycy dendrologicznej dokonano na podstawie wyników badań własnych materiałów oraz eksperymentów heurystycznych wspieranych studium literaturowym. Na podstawie wykonanej analizy ilościowej, prezentowanej w artykule najwyżej ocenione zostały odlewnicze stopy aluminium. Stwierdzono także, że obróbka laserowa jest technologią o najwyższym potencjale i atrakcyjności w kontekscie obróbki powierzchniowej odlewniczych stopów aluminium. Przeprowadzone badania metalograficzne dają podstawę do stwierdzenia, że stopowanie lub wtapianie laserowe z zastosowaniem proszków ceramicznych będzie realizowane z powodzeniem w przypadku podłoża aluminiowego, cząstki proszku będą rozprowadzane równomiernie w badanej warstwie powierzchniowej, poszczególne warstwy będą pozbawione wad i pęknięć oraz będą ściśle przylegały do osnowy aluminiowej. Mając na uwadze powyższe przesłanki należy pamiętać, że dynamiczny rozwój w zakresie aplikacji oferowanych w szczególności przez branżę motoryzacyjną, przemysł lotniczy, sektor wojskowy, sportowy oraz sektor z zakresu inżynierii lądowej bardzo często wymaga stosowania strategii związanej z działaniem długoterminowym