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- Malmsten, A, et al.
(författare)
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Temperature-dependent adsorption and surface forces in aqueous ethyl(hydroxyethyl)cellulose solutions
- 1991
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 7, s. 988-994
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Tidskriftsartikel (refereegranskat)abstract
- Forces between hydrophobized mica surfaces across an aqueous solution of ethyl(hydroxyethyl)cellulose (EHEC) have been studied, inter alia, as a function of surface separation and temperature. EHEC adsorbs strongly to hydrophobic surfaces in a rather flat conformation. The force is reversible on approach and separation up to a temperature of about 40°C. As the temperature was increased from 20°C to 37°C, which is slightly above the cloud point (CP=35°C), the adsorbed amount increased by a factor of three. The force remained monotonically repulsive, despite the fact that the temperature was higher than CP. On increasing the temperature further, the adsorbed amount, as well as the thickness of the adsorbed layer (at a high compressional force), remains essentially unchanged. However, due to the decreased solvency, there is a contraction of the outer part of the adsorbed layer. The force was essentially repulsive at 41°C, with only a very weak attraction observed on separating the surfaces. At 52°C, a weak attraction was observed on both approach and separation, as would be expected in a significantly worse than q-solvent. As the temperature was decreased again, the adsorbed amount as well as the compressed adsorbed layer thickness decreased. The adsorbed amount was the same (within experimental uncertainty) after heating as before. However, the force curve was shifted outwards after heating as compared to the situation before heating. Hence, the temperature dependence of the adsorption, in the absence of constraints on the adsorbed amount, is not completely reversible, at least over the incubation time used (12 h).
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- Nordebo, S, et al.
(författare)
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Noise Reduction Using an Adaptive Microphone Array for Speech Recognition in a Car
- 1993
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Konferensbidrag (refereegranskat)abstract
- TIGS paper describes an evaluation of an adaptive microphone array with respect to speech recognition performauce in a tar. The microphone array is compared KO two conventional microphones of different rypes. The speech recognition device is aimed to be a part of a man/maehine-interface between the driver and tar information services.
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- Parker, JL, et al.
(författare)
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Plasma modification of mica
- 1990
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Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 134, s. 449-458
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Tidskriftsartikel (refereegranskat)abstract
- When mica is exposed to a low temperature nonpolymer-forming plasma the surface structure is altered by a combination of sputtering and chemical reaction with reactive species in the plasma. The chemical composition of the surface is altered without a significant increase in surface roughness under optimal conditions. The effect of the plasma process parameters (exposure time, power, flow rate, and pressure) on the extent of surface modification has been investigated by means of ESCA and contact angle measurements. After exposure to water vapor plasma the mica surface becomes reactive to silanation with chlorosilanes in the gas phase. The durability of mica surfaces modified by plasma treatment and subsequent reaction with some chlorosilanes has been investigated. The forces between water plasmatreated surfaces after silanation have been measured using a surface force apparatus.
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- Öhlander, Björn, et al.
(författare)
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Delineation and character of the Archaean-Proterozoic boundary in northern Sweden
- 1993
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Ingår i: Precambrian Research. - 0301-9268 .- 1872-7433. ; 64:1-4, s. 67-84
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Tidskriftsartikel (refereegranskat)abstract
- Before the deposition of a Proterozoic cover and the repeated Proterozoic reworking of the older rocks, the presently exposed Archaean areas in northern Sweden formed part of a coherent craton. In the present study, we have used Sm---Nd isotopic analyses of Proterozoic granitoids and metavolcanics to delineate the Archaean palaeoboundary. In a regional context, the transition from strongly negative εNd(t) values in the northeast to positive values in the southwest is distinct, and approximately defines the border of the old craton. The Archaean palaeoboundary extends in a WNW direction, and is subparallel to the longitudinal axis of the Skellefte sulphide ore district but it is situated ≈ 100 km farther to the north. The ≈ 1.9 Ga old granitoids on the two sides of the palaeoboundary were all formed in compressional environments, but those situated to the north have higher contents of LILE and LREE at similar contents of Si. This indicates that they were generated in an area with thicker crust and supports the location of the Archaean-Proterozoic palaeoboundary. There is no simple correlation between the Archaean palaeoboundary, as defined by the isotopic results, and any of the major fracture systems as interpreted from regional geophysical measurements. Reflection seismic work indicates that juvenile volcanic-arc terrains to the south have been thrust onto the Archaean craton. Possible thrust faults have been identified from aeromagnetic measurements. Rifting of the Archaean craton created a passive margin ≈ 2.0 Ga ago. Spreading shifted to convergence with subduction beneath the Archaean continent ≈ 1.9 Ga ago. Subsequently, the resulting juvenile volcanic arc collided with the old continent, and the Archaean palaeoboundary as existing today was formed by a collision characterized by overthrusting. The boundary then was disturbed by later deformation predominantly along NNE-trending fracture systems.
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