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Graphene, a two-dimensional carbon allotrope, exhibits excellent optoelectronic properties. The assembly of graphene into films provides a platform to deepen the study of its interaction with varying surfaces, to engineer devices, and to develop functional materials. A general approach to produce graphene films consists of preparing a dispersion and laying it on a substrate of choice, followed by solvent evaporation. Here, we report the preparation of stable suspensions of new types of graphene nanomaterials namely, graphene nanoflowers (GNFs) and multi-layer graphene (MLG) flakes, in ethanol,N,N-dimethylformamide (DMF), andN-methyl-2-pyrrolidone (NMP). Sprayable suspensions of both GNFs and MLG were prepared in DMF/ethanol, which showed high stability, without addition of any surfactant. The stable suspensions were used to deposit micrometer-thick MLG/GNF films on glass substrates. Calculations of initial droplet size and of timescale of droplet evaporation are performed and possible thermophoretic effects on droplet deposition discussed as well. Coating glass substrates with a methacrylic acid–methyl methacrylate (MA) copolymer prior to the deposition significantly improved the adhesion of the nanomaterials to the substrate. With the MA coating, a substrate coverage of nearly 100% was achieved at 14-min spraying time for 0.05 wt% GNF and 0.1 wt% MLG suspensions. Raman spectra of the GNF and MLG films reveal that the films were made of MLG in which the individual graphene layers rotated from each other as in turbostratic graphene. This work provides a general approach to prepare graphene nanomaterial suspensions and to create films for a variety of applications. The spraying process applied in the current work is highly scalable and allows control of film characteristics through process parameters. Copyright 2015 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

Nanostructured lithium iron phosphate is a promising alternative for the positive electrode of next generation Li-ion batteries. The cost of $$\hbox {LiFePO}_{4}$$ material can be reduced by employing alternative low-cost precursors. In this study, iron sulphate heptahydrate produced as a by-product of industrial processing was utilised in aerosol-assisted nanoparticle synthesis. Aqueous precursor solution droplets were heated to 800 $$^{\circ}$$ C in a laminar flow reactor to achieve formation of $$\hbox {LiFePO}_{4}$$ with crystallite and particle size of about 60 and 300 nm, respectively. High fraction of two polymorphs of $$\hbox {LiFePO}_{4}$$ was found in the product powder. The fraction of the olivine polymorph was found to increase under reducing reaction atmosphere, while greater abundance of the high-pressure polymorph was obtained with an iron rich precursor stoichiometry. Hence, it was shown that the low-cost precursors can be used in aerosol-assisted synthesis of $$\hbox {LiFePO}_{4},$$ and the product composition can be fine tuned to the requirements of the application by varying the process parameters. [ABSTRACT FROM AUTHOR]

Multiplestudies show that particulate mass (PM) generated fromincomplete wood combustion may induce adverse health issues in humans.Previous findings have shown that also the PM from efficient woodcombustion may induce enhanced production of reactive oxygen species(ROS), inflammation, and cytotoxicity in vitroand in vivo. Underlying factors of these effects may be tracedback to volatile inorganic transition metals, especially zinc, whichcan be enriched in the ultrafine fraction of biomass combustion particulateemission. In this study, nanoparticles composed of potassium, sulfur,and zinc, which are the major components forming inorganic fine PM,were synthesized and tested in vitro. In addition, in vitrotoxicity of PM from efficient combustion of woodchips was compared with that of the synthesized particles. Cytotoxicity,cell cycle arrest, ROS generation, and tumor necrosis factor alpharelease were related to zinc concentration in PM. Potassium sulfateand potassium carbonate did not induce toxic responses. In light ofthe provided data, it can be concluded that zinc, enriched in woodcombustion emissions, caused the toxicity in all of the measured endpoints. [ABSTRACT FROM AUTHOR]

Organic compounds can enhance the hygroscopic properties of insoluble dust particles and thereby affect their cloud condensation nuclei activity in the atmosphere. In this study, Arizona Test Dust (ATD) particles were exposed to oxidized organic vapors from the ozonolysis of α-pinene in a laboratory chamber. The particle size-dependent morphology, inorganic and organic composition and hygroscopic properties were studied. The dust consisted of particles with a range of morphologies from spherical to geometrical, with a size range from 50 nm to 1 µm. Exposure to oxidized organics resulted in a separate mode of secondary organic aerosol (SOA) particles with size ranging below 100 nm and a well-mixed ATD + SOA mode at larger sizes. The O:C mole ratio for the organics produced from α-pinene ozonolysis was stable at 0.4 ± 0.05 in all experiments. The results showed that the hygroscopicities of the ATD particles with a diameter of 100-150 nm were enhanced by a factor of four with the addition of SOA, corresponding to a particulate organic volume fraction of ~0.6 and an average κ of 0.09. [ABSTRACT FROM AUTHOR]

Gaseous and particulate emissions from a ship diesel research engine were elaborately analysed by a large assembly of measurement techniques. Applied methods comprised of offline and online approaches, yielding averaged chemical and physical data as well as time-resolved trends of combustion by-products. The engine was driven by two different fuels, a commonly used heavy fuel oil (HFO) and a standardised diesel fuel (DF). It was operated in a standardised cycle with a duration of 2 h. Chemical characterisation of organic species and elements revealed higher concentrations as well as a larger number of detected compounds for HFO operation for both gas phase and particulate matter. A noteworthy exception was the concentration of elemental carbon, which was higher in DF exhaust aerosol. This may prove crucial for the assessment and interpretation of biological response and impact via the exposure of human lung cell cultures, which was carried out in parallel to this study. Offline and online data hinted at the fact that most organic species in the aerosol are transferred from the fuel as unburned material. This is especially distinctive at low power operation of HFO, where low volatility structures are converted to the particulate phase. The results of this study give rise to the conclusion that a mere switching to sulphur-free fuel is not sufficient as remediation measure to reduce health and environmental effects of ship emissions.