| 1. |
- Fredin, Maria Fritsch, 1970, et al.
(författare)
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Predicting and monitoring colitis development in mice by micro-computed tomography
- 2008
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Ingår i: Inflammatory Bowel Diseases. - : Oxford University Press (OUP). - 1078-0998 .- 1536-4844. ; 14:4, s. 491-499
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Computed tomography (CT) has been developed as a tool for monitoring human inflammatory bowel disease (IBD). The aim of this study was to evaluate colon wall thickness as a noninvasive marker in the dextran sodium sulfate (DSS) mouse model of colitis using micro-CT. METHODS: Mice were examined by micro-CT 1, 2, or 4 times between day 0 (d0) and d26 after induction of colitis to document the kinetics of changes in colon wall thickness and its relation to colitis development. RESULTS: DSS-treated mice displayed a significantly thicker colon wall at all timepoints (days 5, 8, 12, 19, and 26) investigated compared to healthy controls. Colon wall thickness showed a good correlation to the macroscopic grading of colitis (r = 0.81). The increase in colon wall thickness occurred mainly during the acute phase of colitis (between days 5 and 12) and did not progress much further in the chronic phase of colitis (d26). Colon wall thickness at d26 was thereby predicted by measurements at d12. All mice did not respond equally to DSS and this difference was manifest during the first 2 weeks of colitis, providing an important tool in stratifying responders from nonresponders. CONCLUSIONS: While the potential impact of handling and anesthesia should be considered on repeated micro-CT, irradiation exposure during repeated micro-CT did not affect the development of colitis. Thus, the results suggest that micro-CT can be used for monitoring and prediction of the inflammatory response in mouse colitis in future therapeutic studies.
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| 2. |
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| 3. |
- Jafri, Hassan, et al.
(författare)
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Control of Conductivity in Graphene by Formation of Defects
- 2008
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Ingår i: AVS 55th International Symposium & Exhibition 2008, October 19-24, Boston, USA.
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Konferensbidrag (refereegranskat)abstract
- Due to their large surface areas, the conductivity of graphene and carbonnano-sheets depends strongly on their chemical environment. This is thebase for future environmental sensors containing graphene sheets. Here, abinitiocalculations propose a possibility of conductivity increase. In theexperiment, a 1-2 orders of magnitude increase of the conductivity isobserved experimentally on sub-nanometTe carbon nano-sheets by using anin-situ nano-manipulation set-up. The conductivity of the graphene sheetswas assessed from first-principle simulations. Insertion of defects in thegraphene sheets can lead to a strong increase of the conductivity of singlegraphene sheets. To study this result experimentally, we carried outconductivity measurements on sub-nanometre graphene nano-sheets that aredeposited on W -substrates by radio-frequency plasma-enhanced chemicalvapour deposition. This deposition process creates free-standingmicrometer-sized carbon nano-sheets with sub-nanometre thickness. Thesenano-sheets were exposed to an acid treatment. It has been shown recentlythat such acid treatment creates defects in these sheets. Using a nanomanipulatorinside a scanning electron microscope, we individuallycontacted the nano-sheets and measured their resistance as a function oftheir functionalization. From more than 1000 measurements we obtain a 1-2order of magnitude increase of conductivity in the functionalised carbonnano-sheets as compared to just water treated or untreated carbon nanosheets.This result corresponds well to the conductivity change obtainedfrom theory. This study makes it possible to create environmental sensorsbased on graphene like carbon nano-sheets.
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| 5. |
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| 6. |
- Johansson, Anders, et al.
(författare)
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Fabrication of High-Aspect-Ratio Prussian Blue Nanotubes Using a Porous Alumina Template
- 2005
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 5:8, s. 1603-1606
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Tidskriftsartikel (refereegranskat)abstract
- Prussian blue nanotubes were fabricated by using a sequential deposition technique inside the 60-nm well-ordered pores of anodic alumina. By varying the deposition parameters and the dimensions of the template, we could tailor the length and the outer as well as the inner diameter of the tubes. The nanotubes were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD).
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| 8. |
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| 9. |
- Rooth, Mårten, et al.
(författare)
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Atomic layer deposition of titanium dioxide nanostructures using carbon nanosheets as a template
- 2009
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 311:2, s. 373-377
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured films of anatase TiO2 is deposited on carbon nanosheet (CNS) templates using atomic layer deposition (ALD). The high-surface area of the CNS together with the unique step coverage of the ALD process makes it possible to obtain sheet-like TiO2 nanostructures, for use in potential applications, e.g. photocatalysis and photovoltaics. A problem with ALD on CNS was the low nucleation rate giving TiO2 films with pinholes. It is shown that introduction of defects by an acid-treatment process can be used to control initial nucleation and growth of the films. The TiO2 on the defect-rich CNS nucleates faster and results in a film with no observable pinholes consisting of crystalline grains in an amorphous matrix.
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| 10. |
- Rubino, Stefano, 1978-, et al.
(författare)
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In-situ contacting of nanosheets and remote EMCD
- 2009
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Ingår i: 2nd International Workshop on Remote Electron Microscopy and In Situ Studies, Gothenburg, Sweden 16-18 November 2009.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 11. |
- Widenkvist, Erika, et al.
(författare)
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Fabrication of graphene by bromine-intercalation and sonochemical exfoliation
- 2009
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Konferensbidrag (refereegranskat)abstract
- We present a method of producing suspensions of graphene sheets by combining intercalation and mild sonication. Ultrasonic treatment of graphite leads to the formation of small graphene-like flakes in solution. The delamination of the graphite is dramatically increased by intercalation of bromine. 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. 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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| 12. |
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| 13. |
- 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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| 14. |
- Widenkvist, Erika, et al.
(författare)
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Mild sonochemical exfoliation of bromine-intercalated graphite a new route towards graphene
- 2009
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Ingår i: Journal of Physics D. - : IOP Publishing Ltd. - 0022-3727 .- 1361-6463. ; 42:11, s. 112003-
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Tidskriftsartikel (refereegranskat)abstract
- A method to produce suspensions of graphene sheets by combining solution-based bromine intercalation and mild sonochemical exfoliation is presented. Ultrasonic treatment of graphite in water leads to the formation of suspensions of graphite flakes. The delamination is dramatically improved by intercalation of bromine into the graphite before sonication. The bromine intercalation was verified by Raman spectroscopy as well as by x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show an almost ten times lower interlayer binding energy after introducing Br2 into the graphite. Analysis of the suspended material by transmission and scanning electron microscopy (TEM and SEM) revealed a significant content of few-layer graphene with sizes up to 30 µm, corresponding to the grain size of the starting material
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| 15. |
- Widenkvist, Erika, et al.
(författare)
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Selected area deposition of multiwalled carbon nanotubes from solution
- 2007
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 45:14, s. 2732-2736
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Tidskriftsartikel (refereegranskat)abstract
- A simple method is described for the area-selective deposition of multiwalled carbon nanotubes (MWCNTs) from solution. Selectivity is achieved by functionalizing the MWCNTs with groups that adsorbs preferentially on specific areas of a patterned substrate. Well-characterized octadecylester-functionalized MWCNTs are adsorbed directly from solution on to the substrate. The non-polar hydrocarbon chains interact more strongly with non-polar hydrogen-terminated Si surfaces than do polar oxide surfaces and this gives rise to area-selective adsorption of the MWCNTs on a patterned Si/SiO2 substrate. Potential applications of this method and its application for other types of patterned substrates are discussed.
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| 16. |
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| 17. |
- Widenkvist, Erika, et al.
(författare)
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Synthesis of Nanostructed Tungsten Oxide Thin Films
- 2008
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 8:10, s. 3750-3753
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Tidskriftsartikel (refereegranskat)abstract
- A facile and inexpensive method to produce thin films of nanostructured tungsten oxide is described. A nanocrystalline tungstite (WO3·H2O) film is spontaneously formed when a tungsten substrate is immersed in nitric acid at elevated temperatures. The resulting thin film is composed of plate-like tungstite crystals with edges preferentially directed out from the substrate surface. The tungstite can easily be transformed into WO3 by annealing. Patterned WO3·H2O/W structures can be obtained by a combination of lithographic techniques and etching. In this study, the effect of exposure time, acid concentration, and temperature on the microstructure of the films has been investigated. The potential of this inexpensive synthesis method to produce large-area coatings of nanostructured tungsten oxide as well as patterned films makes it interesting for several different applications, such as batteries, gas sensors, and photocatalysts.
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