| 1. |
- Skedung, Lisa, et al.
(författare)
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Tribology, texture and touch
- 2014
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Ingår i: 5th World Tribology Congress, WTC 2013. - 9781634393522 ; , s. 2270-2273
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Konferensbidrag (refereegranskat)
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| 2. |
- Hansson, Petra M., et al.
(författare)
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Robust Hydrophobic Surfaces Displaying Different Surface Roughness Scales While Maintaining the Same Wettability
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:13, s. 8153-8159
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Tidskriftsartikel (refereegranskat)abstract
- A range of surfaces coated with spherical silica particles, covering the size range from nanometer to micrometer, have been produced using Langmuir-Blodgett (LB) deposition. The particles were characterized both in suspension and in the Langmuir trough to optimize the surface preparation procedure. By limiting the particle aggregation and surface layer failures during the preparation steps, well-defined monolayers with a close-packed structure have been obtained for all particle sizes. Thus, this procedure led to structured surfaces with a characteristic variation in the amplitude and spatial roughness parameters. In order to obtain robust surfaces, a sintering protocol and an AFM-based wear test to determine the stability of the deposited surface layer were employed. Hydrophobization of the LB films followed by water contact angle measurements showed, for all tested particle sizes, the same increase in contact angle compared to the contact angle of a flat hydrophobic surface. This indicates nearly hexagonal packing and gives evidence for nearly, complete surface wetting of the surface features.
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| 3. |
- Skedung, Lisa, et al.
(författare)
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Feeling small : Exploring the Tactile Perception Limits
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. 2617-
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Tidskriftsartikel (refereegranskat)abstract
- The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 mu m and amplitudes between 7 nm and 4.5 mu m. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants, and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties - the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale.
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| 4. |
- Stenler, S., et al.
(författare)
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Micro-minicircle gene therapy : Implications of size on fermentation, complexation, shearing resistance, and expression
- 2014
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Ingår i: Molecular Therapy Nucleic Acids. - : Elsevier BV. - 2162-2531. ; 3, s. e140-
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Tidskriftsartikel (refereegranskat)abstract
- The minicircle (MC), composed of eukaryotic sequences only, is an interesting approach to increase the safety and efficiency of plasmid-based vectors for gene therapy. In this paper, we investigate micro-MC (miMC) vectors encoding small regulatory RNA. We use a construct encoding a splice-correcting U7 small nuclear RNA, which results in a vector of 650 base pairs (bp), as compared to a conventional 3600 bp plasmid carrying the same expression cassette. Furthermore, we construct miMCs of varying sizes carrying different number of these cassettes. This allows us to evaluate how size influences production, supercoiling, stability and efficiency of the vector. We characterize coiling morphology by atomic force microscopy and measure the resistance to shearing forces caused by an injector device, the Biojector. We compare the behavior of miMCs and plasmids in vitro using lipofection and electroporation, as well as in vivo in mice. We here show that when the size of the miMC is reduced, the formation of dimers and trimers increases. There seems to be a lower size limit for efficient expression. We demonstrate that miMCs are more robust than plasmids when exposed to shearing forces, and that they show extended expression in vivo.
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| 5. |
- Stubenrauch, C., et al.
(författare)
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Mixtures of n-dodecyl-beta-D-maltoside and hexaoxyethylene dodecyl ether : Surface properties, bulk properties, foam films, and foams
- 2010
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 155:1-2, s. 5-18
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Tidskriftsartikel (refereegranskat)abstract
- Mixtures of the two non-ionic surfactants hexaoxyethylene dodecyl ether (C12E6) and n-dodecyl-beta-D-maltoside (beta-C(12)G(2)) were studied with regard to surface properties, bulk properties, foam films, and foams. The reason for studying a mixture of an ethylene oxide (CiEj) and a sugar (C(n)G(m),) based surfactant is that despite being non-ionic, these two surfactants behave quite differently. Firstly, the physico-chemical properties of aqueous solutions of C(n)G(m) surfactants are less temperature-sensitive than those of CiEj solutions. Secondly, the surface charge density q(0) of foam films stabilized by C(n)G(m) surfactants is pH insensitive down to the so-called isoelectric point, while that of foam films stabilized by CiEj surfactants changes linearly with the pH. The third difference is related to interaction forces between solid surfaces. Under equilibrium conditions very high forces are needed to expel beta-C(12)G(2) from between thiolated gold surfaces, while for C12E6 low loads are sufficient. Fourthly, the adsorption of C12E6 and beta-C(12)G(2) on hydrophilic silica and titania, respectively, is inverted. While the surface excess of C12E6 is large on silica and negligible on titania, beta-C(12)G(2) adsorbs very little on silica but has a large surface excess on titania. What is the reason for this different behaviour? Under similar conditions and for comparable head group sizes, it was found that the hydration of CiEj surfactants is one order of magnitude higher but on average much weaker than that of C(n)G(m) surfactants. Moreover, C(n)G(m) surfactants possess a rigid maltoside unit, while CiEj surfactants have a very flexible hydrophilic part. Indeed, most of the different properties mentioned above can be explained by the different hydration and the head group flexibilities. The intriguing question of how mixtures of CiEj and C(n)G(m) surfactants would behave arises organically. Thus various properties of C12E6 + beta-C(12)G(2) mixtures in aqueous solution have been studied with a focus on the 1:1 mixture. The results are compared with those of the single surfactants and are discussed accordingly.
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| 6. |
- Thormann, Esben, et al.
(författare)
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Embedded proteins and sacrificial bonds provide the strong adhesive properties of gastroliths
- 2012
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 4:13, s. 3910-3916
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Tidskriftsartikel (refereegranskat)abstract
- The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO3. The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude.
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