| 1. |
- Gane, P. A. C., et al.
(författare)
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Comparison of NMR cryoporometry, mercury intrusion porosimetry, and DSC thermoporosimetry in characterizing pore size distributions of compressed finely ground calcium carbonate structures
- 2004
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 43:24, s. 7920-7927
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates for the first time how mercury intrusion porosimetry (MIP), NMR-based cryoporometry, and DSC-based thermoporosimetry compare in revealing the porous characteristics of ground calcium carbonate structures compacted over a range of pressures. The comparison is made using the same source samples throughout. MIP, a much-used method in the characterization of porous structures, has the drawback that the high pressure needed to intrude the mercury may either distort the skeletal porous structure of the sample, especially when compressible materials such as cellulose or binders/latex are present, or lead to a reduction in the measured number of large pores due to the shielding by smaller pores. These effects have previously been addressed using bulk modulus corrections and by modeling the structure permeability to account for the potential shielding. Cryoporometry gives detailed information about the pore size distribution of an imbibition saturated structure. Thermoporosimetry is a relatively new candidate in this field, and it yields both pore size distribution and pore volume. Currently it is somewhat limited in the pore size range detectable, but it is relevant to pigmented coatings. Its potential is identified for capturing the pores involved in the progress of imbibition before saturation is reached.
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| 2. |
- Chow, J.M., et al.
(författare)
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Randomized benchmarking and process tomography for gate errors in a solid-state qubit
- 2009
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 102:9
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1±0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory.
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| 3. |
- Bishop, Lev S., et al.
(författare)
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Proposal for generating and detecting multi-qubit GHZ states in circuit QED
- 2009
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11, s. 073040-
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Tidskriftsartikel (refereegranskat)abstract
- We propose methods for the preparation and entanglement detectionof multi-qubit Greenberger–Horne–Zeilinger (GHZ) states in circuit quantumelectrodynamics. Using quantum trajectory simulations appropriate for thesituation of a weak continuous measurement, we show that the joint dispersivereadout of several qubits can be utilized for the probabilistic production ofhigh-fidelity GHZ states. When employing a nonlinear filter on the recordedhomodyne signal, the selected states are found to exhibit values of theBell–Mermin operator exceeding 2 under realistic conditions. We discuss thepotential of the dispersive readout to demonstrate a violation of the Merminbound, and present a measurement scheme avoiding the necessity for fulldetector tomography.
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| 4. |
- Hansson, P. M., et al.
(författare)
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Effect of local curvature on the interaction between hydrophobic surfaces
- 2010
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Ingår i: Nanotechnology 2010: Advanced Materials, CNTs, Particles, Films and Composites - Technical Proceedings of the 2010 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2010. - 9781439834015 ; , s. 61-64
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Konferensbidrag (refereegranskat)abstract
- Surface structure, including roughness and chemical heterogeneities, is known to be of importance for the surface interaction forces observed between hydrophobic and superhydrophobic surfaces. In this study, silica particles have been used to prepare structured particulated surfaces with a controlled roughness using Langmuir-Blodgett deposition or a drop coating technique. The surfaces were characterized by SEM and AFM. The AFM colloidal probe technique was employed for probing the interaction between a micro-size hydrophobic particle and hydrophobic surfaces with a sintered and silanized nano-sized silica particle monolayer. These measurements indicate that the adhesion force is increased by a decrease in particle size. Larger roughness gives larger crevices on the surface and more air/vapor accumulation but the capillary growth is impaired since the three-phase line (solid-liquid-air) has to move over a longer distance with an increase in the size of the surface features.
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| 5. |
- Hansson, Petra M., et al.
(författare)
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Effect of surface depressions on wetting and interactions between hydrophobic pore array surfaces
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:30, s. 11121-11130
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Tidskriftsartikel (refereegranskat)abstract
- The surface structure is known to significantly affect the long-range capillary forces between hydrophobic surfaces in aqueous solutions. It is, however, not clear how small depressions in the surface will affect the interaction. To clarify this, we have used the AFM colloidal probe technique to measure interactions between hydrophobic microstructured pore array surfaces and a hydrophobic colloidal probe. The pore array surfaces were designed to display two different pore spacings, 1.4 and 4.0 ÎŒm, each with four different pore depths ranging from 0.2 to 12.0 ÎŒm. Water contact angles measured on the pore array surfaces are lower than expected from the Cassie-Baxter and Wenzel models and not affected by the pore depth. This suggests that the position of the three-phase contact line, and not the interactions underneath the droplet, determines the contact angle. Confocal Raman microscopy was used to investigate whether water penetrates into the pores. This is of importance for capillary forces where both the movement of the three-phase contact line and the situation at the solid/liquid interface influence the stability of bridging cavities. By analyzing the shape of the force curves, we distinguish whether the cavity between the probe and the surfaces was formed on a flat part of the surface or in close proximity to a pore. The pore depth and pore spacing were both found to statistically influence the distance at which cavities form as surfaces approach each other and the distance at which cavities rupture during retraction.
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| 6. |
- Kamel, H., et al.
(författare)
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Characterization of ink adhesion failure; effect of pre-dampening of carbonate containing coatings
- 2008
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Ingår i: TAPPI Advanced Coating Fundamentals Symposium Proceedings. - : TAPPI Press. ; , s. 228-241
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Konferensbidrag (refereegranskat)abstract
- To attain an improved knowledge about ink adhesion during offset printing we have developed a laboratory procedure to measure adhesion failure between ink and coated paper during ink setting. This paper describes the technique and a special case, where a normal coating and a coating with excess dispersing agent, in the form of sodium polyacrylate, have been printed. Characterization of the areas where the adhesion had failed at the pull-off points after tack testing was done by determining "white" spots in the retained print using image analysis. The "white" spots represent areas where ink has detached from the coating after contact with a rubber coated cylinder. This area is referred to as adhesion failure area (AFA). A minimum in AFA at the point of maximum in tack force was found for both coatings where the print was applied onto dried coating. When the coatings, however, were pre-damped, AFA increased on the normal coating over a short time period, independent of the dampening level. For the coating with excess dispersant, on the other hand, the higher dampening level strongly increased the AFA. The strong impact of excess dispersing agent in this work may be explained by a number of related effects, including increased polarity of the coating surface, and an associated moisture layer, and an effective reduction of fine pores due to water-swelling polyacrylate that blocks these pores.
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| 7. |
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| 8. |
- Wallqvist, Viveca, et al.
(författare)
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Fluid transport in compacted porous talc blocks
- 2008
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Ingår i: Fluid Dynamics & Materials Processing. - 1555-256X .- 1555-2578. ; 4:2, s. 85-98
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Tidskriftsartikel (refereegranskat)abstract
- It has been shown that talc powder can be compacted into tablets with a preferred orientation of the platelets. The tablets can be obtained with different controlled porosity depending on pressing methods and applied pressure. The tablets can be obtained with or without additives, which may, in turn, be adsorbed. The orientation of the high aspect ratio platy talc, the surface chemistry imparted by the additives and the transported fluid influence the imbibition and permeation rates. Non-polar hexadecane displays a higher imbibition and permeability than water for all particulate orientations during short timescale absorption, likely due to the oleophilic nature of talc, and thus a more complete filling of the pores for non-polar liquids is to be expected. At longer timescales water is imbibed either at a similar rate to hexadecane or faster depending on the surface chemistry generated by additives leading to hydrophilicity. The swelling of the added polymers used to create wettability leads to break-up of the structure and exposure of hydrophilic surfaces for more rapid imbibition. It is not possible, therefore, to measure reliably the water uptake parameters when talc is fully dispersed with surfactants. Furthermore, dispersing agents tend to contribute to the blocking of pores and throats in the swollen state, and so a limitation in total imbibed volume occurs. The permeability under pressure is also inhibited by additives, which supports the suggestion of partial blockage of the pores and throats. When the individual talc crystal c axes, defining the perpendicular to the [001] planes, are oriented 90° to the primary average liquid flow direction, i.e. are oriented in a planar configuration to the flow, imbibition and permeation of wetting liquid are increased. This is assumed to be due to decreased tortuosity, provided the liquid is wetting in respect to the oriented edge surface. However, non-wetting liquids in respect to all, or geometrically dependent, orientations are subject also to the surface chemistry presented by the orientation, i.e. whether the talc is primarily displaying OH-groups or not, or adsorbed species aiding wetting by the liquid. Measurements where additives are not strongly adsorbed are complicated by the solubility of some wetting and dispersing agents.
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| 9. |
- Wallqvist, Viveca, et al.
(författare)
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Interaction forces between talc and hydrophobic particles probed by AFM
- 2006
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 277:03-jan, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between cleaved talc surfaces and hydrophobic probe particles, silanized silica and thiolized gold, has been investigated employing the atomic force microscopy (AFM) colloidal probe technique. These model systems have hydrophobicities similar to some of the talc-pitch combinations present during pulp and paper manufacture. The talc surfaces used in this study, in the [0 0 1] plane, show a micro-roughness with sharp peaks of up to 3 nm in height. The force profiles obtained demonstrate the predominance of a long-range attractive force. However, the range and magnitude of the attractive force show large variability. The variability of the attractive force, and the frequent observations of clear steps in the force curve demonstrate that it is caused by gas/vapor cavities bridging the Surfaces once the surfaces are brought sufficiently close together. The results suggest that the same mechanism is of importance in applications where talc is used as a collector for pitch.
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