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| 2. |
- Dahl, Andreas, et al.
(författare)
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Traffic-generated emissions of ultrafine particles from pavement-tire interface
- 2006
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 40:7, s. 1314-1323
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Tidskriftsartikel (refereegranskat)abstract
- In a road simulator study, a significant source of sub-micrometer fine particles produced by the road-tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15-50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15-700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7 x 10(11) and 3.2 x 10(12) particles vehicle(-1) km(-1) at speeds of 50 and 70 km h(-1). This corresponds to between 0.1-1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road-tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road-tire interface may be a significant contributor to particle emissions from ultraclean vehicles. (c) 2005 Elsevier Ltd. All rights reserved.
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| 5. |
- Gharibi, Arash
(författare)
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Studies of aerosol particle formation from various sources using ion and electron beam analytical techniques.
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis presents the results of studies of aerosol particle formation using ion and electron beam analytical techniques. The sources of aerosol particle formation studied are the following: 1. production of primary aerosol particles in the high Arctic region during summers 2. emission of ultrafine aerosol particles from wear on the road-tire interface 3. emission of aerosol particles from district heating units operating on three commonly-used biofuels. A source of primary and nearly hydrophobic aerosol particles within the Arctic pack ice region during summers with a composition similar to that of average crustal rock was identified. Wear on the road-tire interface was found to generate numerous ultrafine aerosol particles of varying morphology. The particle number emission factors per vehicle and kilometer driven are similar in magnitude to the tail-pipe exhaust emissions obtained by use of modern engine technology. Particle emissions from the combustion of biomass were characterized in terms of their elemental composition and particle formation mechanisms. List of papers in this dissertation Paper I: Aerosol particle elemental size distributions during the Arctic Ocean expedition in the summer of 2001. Paper II: Summer high Arctic aerosol particles classified using Transmission Electron Microscopy. Paper III: Traffic-generated emissions of ultra fine particles from the road surface-tire interface. Paper IV: Particle emissions from district heating units operation on three commonly used biofuels. Paper V: Laboratory and field test of a method for high-temperature characterization of fly ash and fly ash precursors.
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| 7. |
- Gharibi, Arash, et al.
(författare)
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Tunable transient evolutional behaviours of a four-level atomic vapour and the application to photonic logic gates
- 2009
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 42:5, s. 055502-
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Tidskriftsartikel (refereegranskat)abstract
- The evolutional optical behaviours (turn-on dynamics) of a four-level N-configuration atomic system are considered based on the transient solution to the equations of motion of atomic probability amplitudes. It is shown that the quantum interference between the signal and control fields can lead to the controllable absorption and transparency properties of the atomic vapour. One of the most remarkable properties of the present scheme is that the absorption (or transmittance) of the probe light in the atomic vapour depends on the intensity ratio of the signal field to the control field, and thus the tunable optical features (transparency or opaqueness to the probe light) can be realized by tuning the quantum interferences between the signal and control fields. The present mechanism can be applicable to designs of some new photonic and quantum optical devices such as logic and functional devices as well as optical switches. Two typical photonic logic gates (NOT and NOR gates) designed based on the tunable four-level optical responses are presented as illustrative examples.
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| 8. |
- Qian, Jun, et al.
(författare)
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Colloidal mesoporous silica nanoparticles with protoporphyrin IX encapsulated for photodynamic therapy
- 2009
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Protoporphyrin IX (PpIX)-encapsulated mesoporous silica nanoparticles were synthesized, characterized, and utilized for photodynamic therapy (PDT) of cancer. Silica encapsulation is relatively transparent for activated light and can protect the PpIX against denaturation induced by the extreme bioenvironment. The mesoporous silica can also ensure that the encapsulated PpIX can be well-contacted with oxygen, stimulated, and released. PpIX-encapsulated colloidal mesoporous silica nanoparticles were uptaken by tumor cells in vitro, and the effect of photon-induced toxicity was demonstrated after comparison with some control experiments. The surface of PpIX-encapsulated silica nanoparticles can be grafted with appropriate functionalized groups and conjugated with certain biomolecules for specific targeting.
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| 9. |
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| 10. |
- Strand, M, et al.
(författare)
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Laboratory and field test of a sampling method for characterization of combustion aerosols at high temperatures
- 2004
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 38:8, s. 757-765
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to design and experimentally examine a sampling method for high-temperature aerosols from biomass combustion, in which nucleation and condensation from fly ash forming vapors is controlled. The sampling method includes a high-temperature probe in which the hot gas is diluted and then cooled. Laboratory results from sampling a model aerosol with known concentrations of SiO2 particles and KCl vapor showed that when using a high dilution ratio, the KCl vapor was effectively separated from the aerosol by deposition onto the probe walls. When a lower dilution ratio was used, the KCl vapor generated a distinct nucleation mode when cooled in the probe. The sampling method was also used for sampling flue gas from a circulating fluidized bed boiler fired with forest residues. The results suggest that the major fractions of Ca, K, S, and Zn were present as particles at 780degreesC, whereas most of the Cl and Pb were present as gases. The field results are consistent with results previously reported and indicate that the method can be used for efficient and precise characterization of high-temperature combustion aerosols containing inorganic vapors.
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