| 1. |
- de la Presilla, Roman José, et al.
(författare)
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Grease lubricity in the fretting contact : Are ionic liquids the solution?
- 2023
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 185, s. 108509-
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Tidskriftsartikel (refereegranskat)abstract
- A statistical, energy-based approach is employed to experimentally characterize the ability of different greases to reduce friction when a point contact is subjected to repeated reciprocal displacements of smaller magnitude than the contact diameter. This approach allows the assessment of lubricant fretting performance with respect to its ability to remain within the contact and also its boundary lubrication properties. The results indicate that composition-dependent boundary lubrication properties of greases loaded with non-halogenated ionic liquids containing bis(oxalato)borate ([BOB]) and bis(mandelato)borate ([BMB]) anions can result in no detectable wear and low friction, even under conditions of moderately high pressures and where the original contact area is never fully uncovered. This discovery paves the way for the development of anti-fretting ionic greases.
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| 2. |
- Engman, Cecilia, 1974, et al.
(författare)
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Probing the influence on folding behavior of structurally conserved core residues in P. aeruginosa apo-azurin.
- 2004
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Ingår i: Protein Science. ; 13:10, s. 2706-2715
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Tidskriftsartikel (refereegranskat)abstract
- The effects on folding kinetics and equilibrium stability of core mutations in the apo-mutant C112S of azurin from Pseudomonas aeruginosa were studied. A number of conserved residues within the cupredoxin family were recognized by sequential alignment as constituting a common hydrophobic core: I7, F15, L33, W48, F110, L50, V95, and V31. Of these, I7, V31, L33, and L50 were mutated for the purpose of obtaining information on the transition state and a potential folding nucleus. In addition, residue V5 in the immediate vicinity of the common core, as well as T52, separate from the core, were mutated as controls. All mutants exhibited a nonlinear dependence of activation free energy of folding on denaturant concentration, although the refolding kinetics of the V31A/C112S mutant indicated that the V31A mutation destabilizes the transition state enough to allow folding via a parallel transition state ensemble. Phi-values could be calculated for three of the six mutants, V31A/C112S, L33A/C112S, and L50A/C112S, and the fractional values of 0.63, 0.33, and 0.50 (respectively) obtained at 0.5 M GdmCl suggest that these residues are important for stabilizing the transition state. Furthermore, a linear dependence of ln k(obs)(H2O) on DeltaG(U-N)(H2O) of the core mutations and the putative involvement of ground-state effects suggest the presence of native-like residual interactions in the denatured state that bias this ensemble toward a folding-competent state.
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| 3. |
- Farré-Lladós, Josep, et al.
(författare)
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On the Flow Dynamics of Polymer Greases
- 2022
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Ingår i: Lubricants. - : MDPI. - 2075-4442. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the flow dynamics of polymer greases was investigated using micro-particle image velocimetry. Polymer greases have a different thickener structure, compared to widely used lithium-based greases, and they have the well-known ability to release oil. How these properties affect grease deformation and its ability to flow is investigated and compared to the corresponding behavior of a lithium complex grease with the same consistency. Two main tests were carried out, where velocity profiles in a straight channel were measured and analyzed, and velocity evolution during the transition period from a no-flow to a fully-established flow was measured, respectively. It was found that the polymer grease flow dynamics is different from that of the lithium grease. This indicates that the internal structure of the grease and the grease ability to bleed oil have a strong influence on the deformation on a global scale, which in turn entails other lubricating abilities for the two grease types.
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| 4. |
- Glavatskih, Sergei, et al.
(författare)
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Greases for powertrains: Thickener effect, electric conductivity, and life cycle assessment
- 2023
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Ingår i: JSAE/SAE Powertrains, Energy and Lubricants International Meeting, PFLJAPAN 2023. - : SAE International.
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Konferensbidrag (refereegranskat)abstract
- The paper shows how grease thickener polarity affects performance of the typical powertrain components: gears and rolling element bearings. Greases based on a non-polar polypropylene thickener reduce friction losses (more than 20%) in high-speed deep groove ball bearings and provide a longer service life (more than 2 times) in highly loaded bevel gears, compared to the greases based on polar lithium thickeners. The electrification and sustainability trends have led to additional requirements to be addresses during grease design process: tunable electric conductivity and reduced environment footprint. The grease design challenges caused by the novel requirements and potential solutions are discussed.
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| 5. |
- Grünberg, Raik, et al.
(författare)
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Complementarity of structure ensembles in protein-protein binding.
- 2004
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Ingår i: Structure. ; 12:12, s. 2125-36
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Tidskriftsartikel (refereegranskat)abstract
- Protein-protein association is often accompanied by changes in receptor and ligand structure. This interplay between protein flexibility and protein-protein recognition is currently the largest obstacle both to our understanding of and to the reliable prediction of protein complexes. We performed two sets of molecular dynamics simulations for the unbound receptor and ligand structures of 17 protein complexes and applied shape-driven rigid body docking to all combinations of representative snapshots. The crossdocking of structure ensembles increased the likelihood of finding near-native solutions. The free ensembles appeared to contain multiple complementary conformations. These were in general not related to the bound structure. We suggest that protein-protein binding follows a three-step mechanism of diffusion, free conformer selection, and refolding. This model combines previously conflicting ideas and is in better agreement with the current data on interaction forces, time scales, and kinetics.
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| 6. |
- Johnsson, Filip, 1960, et al.
(författare)
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An experimental study of in-furnace processes and dynamic behaviour of a 235 MWe CFB boiler
- 2004
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Ingår i: VGB PowerTech. - 1435-3199. ; 84:3, s. 82-87
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Tidskriftsartikel (refereegranskat)abstract
- In a project funded by the 5th Framework Programme of the European Union, a 235 MWe Circulating Fluidized Bed (CFB) boiler is investigated with respect to in-furnace processes and dynamic response to load changes. The purpose of the project is to assess the insufficiently known features of large-scale CFB boilers. The furnace of the boiler has a cross-section of 21 x 10 meters and a height of 44 meters. The boiler is located in Turow, Poland, and is operated on a local brown coal.The project is unique in that several measurement ports were opened in the walls of the large CFB furnace for measurements in various locations inside the furnace. Also, a number of techniques were employed with new probes developed for this type of measurements to form a basis for studies of hydrodynamic processes as well as local variations in gas components (such as O2, CO, THC) and solid bed materials. The paper describes the measurement techniques and provides examples of results obtained from the in-situ measurements and from the dynamic response study.
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| 7. |
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| 8. |
- Johnsson, Filip, 1960, et al.
(författare)
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In-furnace processes in a 235 MWe CFB boiler
- 2002
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Ingår i: Proc. of the 7th International Conference on Circulating Fluidized Beds. - 9780920804988 ; , s. 607-614
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Konferensbidrag (refereegranskat)abstract
- In an experimental project funded by the 5th Framework Programme of the European Community (EC), different measurement techniques are used to analyze in-furnace processes in a 235 MWe Circulating Fluidized Bed (CFB) boiler in Turow, Poland. The purpose of the project is to assess the insufficiently known features of large-scale CFB boilers. The furnace of the boiler has a cross-section of 21 x 10 meters and a height of 43 meters. The boiler is operated on a local brown coal. Steady state, as well as dynamic conditions, are studied. The project is unique in two respects: Firstly, several measurement ports are provided in the large CFB furnace for in-situ measurements in various locations on the furnace. Secondly, a number of measurement techniques are employed. These facilitate studies of hydrodynamic processes as well as local variations in gas components (such as O2, CO, THC) and solids materials. The paper describes the measurement techniques and provides examples of the first (hydrodynamic) results obtained by the in-situ measurements.
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