| 1. |
- Eriksson, Emma, 1980, et al.
(författare)
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Optical manipulation and microfluidics for studies of single cell dynamics
- 2007
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Ingår i: Journal of Optics. A, Pure and applied optics. - 1464-4258 .- 1741-3567 .- 1361-6617. ; 9:8, s. 113-121
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Tidskriftsartikel (refereegranskat)abstract
- Most research on optical manipulation aims towards investigation and development of the system itself. In this paper we show how optical manipulation, imaging and microfluidics can be combined for investigations of single cells. Microfluidic systems have been fabricated and are used, in combination with optical tweezers, to enable environmental changes for single cells. The environment within the microfluidic system has been modelled to ensure control of the process. Three biological model systems have been studied with different combinations of optical manipulation, imaging techniques and microfluidics. In Saccharomyces cerevisiae, environmentally induced size modulations and spatial localization of proteins have been studied to elucidate various signalling pathways. In a similar manner the oxygenation cycle of single red blood cells was triggered and mapped using Raman spectroscopy. In the third experiment the forces between the endoplasmic reticulum and chloroplasts were studied in Pisum sativum and Arabidopsis thaliana. By combining different techniques we make advanced biological research possible, revealing information on a cellular level that is impossible to obtain with traditional techniques.
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| 2. |
- Fredriksson, Hans, 1974, et al.
(författare)
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Resonant optical absorption in graphite nanostructures
- 2009
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Ingår i: Journal of Optics A: Pure and Applied Optics. - 1361-6617 .- 1464-4258. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- A systematic investigation of the correlation between optical absorption and the size of graphitenanostructures is presented. Five different samples with structure diameters ranging from ∼160to 330 nm and heights from ∼60 to 190 nm were prepared. The disk-like nanostructures wereetched out of the basal plane surface of highly oriented pyrolytic graphite, using hole-maskcolloidal lithography and oxygen reactive ion etching. Optical absorption spectra forwavelengths between 200 and 2500 nm were then measured. Furthermore, electrodynamicscalculations were conducted to model the optical properties of graphite nanostructures ofsimilar sizes. Both the experimental and the theoretical work revealed resonant absorptioncorrelated to the nanostructure diameters and heights. These absorption peaks are red-shifted,from the visible for the smallest structures to near infrared for the largest. Simultaneously, theintensity of the absorption peaks increases for increasing structure heights, while increasingdiameters results in decreased absorption.
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| 3. |
- Holmgren, Allan, et al.
(författare)
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SER spectra analysis of molecules with D-3h and D-6h symmetry groups
- 1998
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Ingår i: Pure and Applied Optics. - : IOP Publishing. - 0963-9659. ; 7:1, s. 115-117
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of the theory of SER spectra, proposed in a previous paper, the SER spectra of 1,3,5-trifluorobenzene, 1,3,5-trideuteriobenzene, benzene and hexafluorobenzene are analysed. It is demonstrated that the bands, caused by the totally symmetric modes and by the mode transforming as the d(z) moment experience large enhancement. The existence of a large number of forbidden bands in the SER spectra is pointed out. Some anomalies in the enhanced spectra are explained by qualitative ideas and by the 'interference phenomenon' of various contributions. It is pointed out that all the observed lines and regularities of the SER spectra can be explained within the framework of the quadrupole and dipole electrodynamical mechanism of the enhancement.
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| 4. |
- Malomed, B. A., et al.
(författare)
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Decay of parametric solitons in a lossy medium with quadratic nonlinearity
- 1996
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Ingår i: Pure and Applied Optics (Print edition) (United Kingdom). - : IOP Publishing. - 0963-9659. ; 5:6, s. 941-946
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made into the evolution of two-wave solitons in a second-haimonic-generation system under the action of weak dissipation. Using the balance equation for the soliton energy and a previously developed variational approximation for its shape, a general evolutional equation is derived for the soliton parameters. The equation is solved explicitly for the asymptotic stage of the evolution
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