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| 2. |
- Humail, Islam S, et al.
(författare)
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Tensile behavior change depending on the varying tungsten content of W--Ni--Fe alloys
- 2007
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Ingår i: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 25:5-6, s. 380-385
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Tidskriftsartikel (refereegranskat)abstract
- Tungsten heavy alloys (WHAs) are metal–metal composites consisting of nearly pure spherical tungsten particles embedded in a Ni–Fe–W or Ni–Co–W or Ni–Cu–W ductile matrix. In this dual phase alloy, there are several complicated relations between the ductile matrix and hard tungsten particles. The aim of this research was to examine the effect of varying tungsten content on the microstructure and mechanical properties of tungsten heavy alloys. The microstructural parameters (grain size, connectivity, contiguity and solid volume fraction) were measured and were found to have a significant effect on the mechanical properties of tungsten-based heavy alloys. The result shows that the binding strength between the W and the matrix phase has a major influence on the ductility of tungsten-based alloys. The larger this binding force is, the better the ductility is.
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| 3. |
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| 4. |
- Teleki, Alexandra, et al.
(författare)
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In Situ Coating of Flame-Made TiO2 Particles with Nanothin SiO2 Films
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:21, s. 12553-12558
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Tidskriftsartikel (refereegranskat)abstract
- Rutile TiO2 particles made by flame spray pyrolysis (FSP) were coated in a single step with SiO2 layers in an enclosed flame reactor. This in situ particle coating was accomplished by a hollow ring delivering hexamethyldisiloxane (HMDSO) vapor (precursor to SiO2) through multiple jets in swirl cross-flow to Al-doped nanostructured rutile TiO2 aerosol freshly made by FSP of a solution of titanium tetraisopropoxide and aluminum sec-butoxide in xylene. The as-prepared powders were characterized by (scanning) transmission electron microscopy (STEM and TEM), energy dispersive X-ray analysis, X-ray diffraction, nitrogen adsorption, electrophoretic mobility, DC plasma optical emission (DCP-OES), and Fourier transform infrared (FT-IR) spectroscopy. The coating quality was assessed further by the photocatalytic oxidation of isopropyl alcohol to acetone. The effect of HMDSO injection point and vapor concentration on product particle morphology was investigated. The titania particles were uniformly SiO2-coated with controlled and uniform thickness at a production rate of about 30 g h(-1) and exhibited limited, if any, photoactivity. In contrast, spraying and combusting equivalent mixtures of the above Si/Al/Ti precursors in the above reactor (without delivering HMDSO through the hollow ring) resulted in particles segregated in amorphous (SiO2) and crystalline (TiO2) domains which exhibited high photocatalytic activity.
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| 5. |
- Teleki, Alexandra, et al.
(författare)
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Role of Gas-Aerosol Mixing during in Situ Coating of Flame-Made Titania Particles
- 2009
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 48:1, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- Rutile TiO(2) particles of 40 nm average diameter were made by flame spray pyrolysis (FSP) and in situ coated with ultrathin (2-4 nm) SiO(2) layers. The spray flame was enclosed by a quartz glass tube while hexarnethyldisiloxane (HMDSO) vapor-laden N(2) was injected in swirling crossflow to and downstream of the flame through a metal torus pipe ring. The as-prepared powders were characterized by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption. The effect of mixing between HMDSO-laden N2 jets and freshly made titania aerosol on product coating quality was investigated by varying systematically the number and gas flowrate through these jets experimentally and by computational fluid dynamics. The coating quality of titanium dioxide was evaluated further by photocatalysis of isopropanol to acetone under UV light using suspensions of the above particles.
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| 6. |
- Teleki, A., et al.
(författare)
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The quality of SiO(2)-coatings on flame-made TiO(2)-based nanoparticles
- 2008
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 18:30, s. 3547-3555
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Tidskriftsartikel (refereegranskat)abstract
- Silica-coated titania nanoparticles are important in sunscreens, UV filters and optical nanocomposites. The surface characteristics (extent of coverage, texture and thickness) of in situ SiO(2)-coated, mostly rutile titania nanoparticles made in one step by flame spray pyrolysis (FSP) were compared to FSP-made mixed (co-oxidized) SiO(2)/TiO(2) ones by transmission electron microscopy (TEM), Raman, FT-IR spectroscopy, electrophoretic mobility and isopropanol chemisorption followed by mass spectroscopy. Increasing the silica content shifted the isoelectric point (IEP) toward that of pure silica for externally mixed SiO(2) and TiO(2), co-oxidized SiO(2)/TiO(2) and low SiO(2) content (< 10 wt%) silicacoated TiO(2) nanoparticles. At higher SiO(2) contents, SiO(2)-coated titania exhibited negative z potentials at all pH values (and thus no IEP) indicating hermetic or complete coverage of the TiO(2) surface by SiO(2) as was confirmed by isopropanol chemisorption. Co-oxidized particles containing segregated TiO(2) and SiO(2) domains exhibited Si-O-Ti and Si-O-Si bonds of higher IR intensity than hermetically-coated TiO(2). The latter exhibited a peak at 1225 cm(-1) attributed to Si-O-Si asymmetric vibrations in contrast to the former.
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| 7. |
- Widenkvist, Erika, et al.
(författare)
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Intercalation and Ultrasonic Treatment of Graphite : a New Synthetic Route to Graphene
- 2008
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Konferensbidrag (refereegranskat)abstract
- We will demonstrate that ultrasonic treatment of a graphite crystal in water can lead to the formation of small graphene-like flakes in solution. The delamination of the graphite can be increased dramatically by intercalation of bromine from a Br2-saturated water solution. After ultrasonic treatment, large amounts of graphene-like flakes with varying thickness are observed in SEM and TEM. They can be adsorbed onto a surface of a suitable substrate by a simple dipping technique. The effect of polar and non-polar solvents as well as adsorption of the graphene on hydrophobic and hydrophilic substrates will be demonstrated and compared. DFT calculations of the intercalation process have been carried out using the SIESTA package and the effect of bromine intercalation on cohesive energy and electronic structure will be discussed and compared with experimental data. Finally, the general approach of using ultrasonic treatment and intercalation as a facile route to graphene synthesis compared to other methods will be discussed.
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| 8. |
- Wurst, FM, et al.
(författare)
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Emerging biomarkers: New directions and clinical applications
- 2005
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Ingår i: Alcoholism: Clinical and Experimental Research. - 0145-6008. ; 29:3, s. 465-473
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes content proceedings of a symposium held at the 2004 Research Society on Alcoholism Scientific Annual Meeting in Vancouver, Canada. The chairs were Friedrich M. Wurst and Raye Litten. The presentations were (1) Introduction, by Raye Litten; (2) Direct Ethanol Metabolites-On the Threshold From Science to Routine Use, by Friedrich M. Wurst; (3) Sialic Acid Index of Plasma Apolipoprotein J (SIJ) as a Viable Marker for Chronic Alcohol Consumption, by Philippe Marmillot; (4) The Emergence of Ethyl Glucuronide (EtG) Testing as a Tool in Monitoring Healthcare Professionals, by Gregory E. Skipper; (5) Application of Biomarkers for Alcohol Use Disorders in Clinical Practice, by Tim Neumann; (6) Utility of Biomarkers in Assessing the Efficacy of Medications for Treating Alcoholism, by Marty Javors; and (7) Discussion, by Raye, Litten.
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