| 1. |
- Brandt, Peter, et al.
(författare)
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Molecular Mechanics (MM3) Parameters for Ruthenium(II)-Polypyridyl Complexes.
- 1998
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Ingår i: Inorganic Chemistry. - 0020-1669 .- 1520-510X. ; 37:16, s. 4120-4127
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Tidskriftsartikel (refereegranskat)abstract
- We have developed molecular mechanics parameters for Ru(II)-polypyridyl coordination compounds with the MM3 force field in MacroModel. X-ray structures, together with a B3LYP frequency calculation on a model system, have been utilized in the parametrization. The performance of the force field and the quality of each parameter is analyzed. A clear qualitative correlation have been found between coordination geometry and emission properties for the ruthenium polypyridyl complexes examined in this paper.
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| 2. |
- Eastoe, Julian, et al.
(författare)
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Interrogation of a dynamic multi-catalyst ensemble in asymmetric catalysis
- 2010
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Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1359-6640. ; 145, s. 27-47
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Tidskriftsartikel (refereegranskat)abstract
- The Trost Standard Ligand (2) is a chiral diphosphine ligand that distinguishes itself by the high selectivity it induces in the Pd-catalysed reactions of allylic substrates that generate slim cyclic or small linear intermediates. However, a range of unusual features, including memory effects, inverse dependence of selectivity and rate on catalyst concentration, high sensitivity to counter-ion, particularly chloride, and decreasing enantioselectivities at lower temperatures, are often encountered, thus requiring considerable optimisation of reaction conditions to attain optimum selectivity. These features can be accounted for by a model involving a dynamic multi-catalyst ensemble. To gain evidence for this model, the manner in which diphosphine 2 interacts with Pd–allyl cations, and in particular the higher-order systems it generates, has been investigated by use of NMR, isotopic labelling, polarimetry, UV, neutron scattering, X-ray crystallography and molecular modeling. Ligand 2 coordinates to Pd–allyl cations to generate a mononuclear P,P-chelate. This is found to readily form non-chelate oligomers, present in a range of forms, including rings, for which high homochiral selectivity in oligomerisation is demonstrated by the technique of pseudoenantiomers. All of these species are in relatively rapid equilibrium, with half-lives for interconversion in the range 2–6 s. Higher-order aggregation is also detected, and thus at even moderate concentrations (>50 mM) large rod-like aggregates are formed.
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| 3. |
- Glavatskih, Sergei, et al.
(författare)
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Influence of oil type on tilting pad journal bearing thermal characteristics
- 2009
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Ingår i: Proceedings of the World Tribology Congress 2009. - Tokyo : Japan Society of Tribologists. - 9784990013998 ; , s. 6183-6186
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The effect of ester-based turbine oil on the performance characteristics of a tilting pad journal bearing was studied. Mineral oils with viscosity grade of 32 and 46 and synthetic oil with viscosity similar to that of the mineral oil VG32 were used. Both mineral and synthetic oils provided similar temperatures. Pad temperature was strongly affected by rotational speed. A slower increase in temperature at higher speeds was caused by the shift in the maximum temperature zone due to the pad thermal crowning. Synthetic oil ran slightly hotter than VG32 mineral oil at lower speeds. At higher speed these oils had almost the same temperatures. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/2009).
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| 4. |
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| 5. |
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| 6. |
- Gøgsig, Thomas M, et al.
(författare)
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Mild and efficient nickel-catalyzed Heck reactions with electron-rich olefins.
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:1, s. 443-52
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Tidskriftsartikel (refereegranskat)abstract
- A new efficient protocol for the nickel-catalyzed Heck reaction of aryl triflates with vinyl ethers is presented. Mild reaction conditions that equal those of the corresponding palladium-catalyzed Heck reaction are applied, representing a practical and more sustainable alternative to the conventional regioselective arylation of vinyl ethers. A catalytic system comprised of Ni(COD)(2) and 1,1'-bis(diphenylphosphino)ferrocene (DPPF) in combination with the tertiary amine Cy(2)NMe proved effective in the olefination of a wide range of aryl triflates. Both electron-deficient and electron-rich arenes proved compatible, and the corresponding aryl methyl ketone could be secured after hydrolysis in yields approaching quantitative. Good functional group tolerance was observed matching the characteristics of the analogous Pd-catalyzed Heck reaction. The high levels of catalytic activity were explained by the intermediacy of a cationic nickel(II) complex potentially responsible for the successive β-hydride elimination and base promoted catalyst regeneration. Although these elementary reactions are normally considered challenging, DFT calculations suggested this pathway to be favorable under the applied reaction conditions.
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| 7. |
- Kassfeldt, Elisabet, et al.
(författare)
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Wear and friction in boundary lubricated contacts
- 2000
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Ingår i: The characteristics of interacting surfaces - a key factor in sustainable and economic products. - Bury St Edmunds : Professional Engineering Publishing Ltd. - 1860582664 ; , s. 195-204
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Konferensbidrag (refereegranskat)
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| 8. |
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| 9. |
- Larsson, Roland, et al.
(författare)
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Base fluid parameters for elastohydrodynamic lubrication and friction calculations and their influence on lubrication capability
- 2001
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Ingår i: Journal of Synthetic Lubrication. - : Wiley. - 0265-6582 .- 1557-6841. ; 18:3, s. 183-198
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Tidskriftsartikel (refereegranskat)abstract
- In this study, base fluid parameters for elastohydrodynamic lubrication (EHL) and friction analyses have been determined experimentally. The viscosity at atmospheric pressure, η0, the pressure-viscosity index, α and the EHL friction coefficient, γ, are important parameters in EHL theory and they are crucial in the selection of efficient lubricants for different applications. This investigation focuses on three important lubrication mechanisms: The capability of forming a separating lubricants film, the friction generated in a lubricated contact, and the height of pressure peaks, such as the outlet pressure spike and pressure ripple caused by surface roughness. The influence of different lubricant parameters on these three mechanism is discussed. The value of α is measured in a Couette high-pressure viscometer, and the value of γ is obtained from a jumping-ball device. Other parameters discussed are temperature-viscosity coefficient, β, bulk modulus, BO, thermal conductivity at atmospheric pressure, λO, and heat capacity unit volume, ρCpO. A comparison between traditional mineral base oils and environmentally adapted oil based on rapeseed oil and synthetic esters contributes to the further understanding of the performance of these new materials in lubrication applications. It is shown that rapeseed oil and synthetic esters have good lubricating properties and are, in most cases, better than mineral oils.
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| 10. |
- Mccarthy, Donald, et al.
(författare)
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Aged environmentally adapted lubricants : Part II: Performance evaluation in boundary lubricated contacts
- 2006
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Ingår i: Automotive and industrial lubrication. - Ostfildern : Techn. Akad. Esslingen. - 3924813620 ; , s. 140-
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Konferensbidrag (refereegranskat)abstract
- Experiments are conducted to compare the performance of fresh and aged samples of three oils in a boundary lubricated contact. These oils are Oil A (a commercially available unsaturated synthetic ester based hydraulic fluid (ISOVG32)), Oil B (a mineral based turbine oil (ISOVG68), and Oil C (a saturated synthetic ester based lubricating fluid (ISOVG46)). Tests are performed using a tin-bronze on steel contact in a pin-on-disc apparatus. Results from these tests provide data relating to friction and wear and their coupling to the aging of the fluids. No evidence of any significant deterioration of lubricant performance is observed for any of the fluids tested. This is an abstract of a paper presented at the 15th International Colloquium Tribology - Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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