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Papers by Len Fisher

Physics World, Aug 1, 2015

With today's world dominated by science, it's vital that politicians understand its inher... more With today's world dominated by science, it's vital that politicians understand its inherently imperfect nature. Len Fisher and John Tesh argue, however, that scientists must also understand the imperfect nature of politics – and offer 12 practical tips for communicating science advice to politicians.

The Kyoto Post-COVID Manifesto For Global Economics

Microscopic Aspects of Adhesion and Lubrication, Proceedings of the 34th International Meeting of the Société de Chimie Physique, 1981

Results are presented of experimental studies on the adhesion of two curved molecularly smooth su... more Results are presented of experimental studies on the adhesion of two curved molecularly smooth surfaces. in these studies adhesion forces and the elastic deformation occurring around the contact zone were measured. the experiments were carried out with surfaces (i) in an inert atmosphere of nitrogen, (ii) in under-saturated vapours, where capillary condensation around the contact zone gives rise to an additional surface tension (meniscus) force, and (iii) in organic liquids. (i) the measured adhesion of two mica surfaces each coated with a monolayer of surfactant (calcium stearate or hexadecyltrimethylammonium-bromide, CTAB) of known surface energies(γSV ∼ 23 erg/cm2 and ∼ 27 erg/cm2, respectively) show that the adhesion force is given by F ≈4πR γSV, where R is the local radius of curvature of the surfaces. the surface profile is non-Hertzian. in particular, when pulled apart the surfaces separate spontaneously once their contact diameter has fallen to < 0.58 of the diameter at equilibrium (under zero external force). (ii) the adhesion force between two mica surfaces in undersaturated vapours of the condensable liquids benzene, cyclohexane and hexane is well described by the theoretical expression based on bulk thermodynamics: F ≈ 4πR γSV = 4πR[γLV cos θ + γSL]. Equilibrium meniscus radii (Kelvin radii) as low as 0.5 nm (relative vapour pressure < 0.1) are sufficient for these condensed liquids to behave as bulk liquid bridges, and since γSL is small the adhesion force is effectively given by F ≈ 4πRR γLV cos θ. (iii) in inert organic liquids, such as cyclohexane and the silicon liquid octamethylcyclotetrasiloxane, the force between two mica surfaces over the last few nanometers is spatially oscillatory – varying between attraction and repulsion – with a periodicity equal to the molecular size. These rapidly decaying oscillatory forces indicate that the molecules are layered near the surfaces, and this layering prevents the surfaces from coming into strong adhesive contact. Addition of trace amounts of water results in a purely attractive, strongly adhesive, force. the implications for lubrication and particle interactions will be discussed.

The Journal of Chemical Physics, 2002

Explicit atom molecular dynamics simulations were used in conjunction with the thermodynamic inte... more Explicit atom molecular dynamics simulations were used in conjunction with the thermodynamic integration method to calculate hydration free energies for short n-alkane molecules, up to C5H12. The OPLS all-atom parameter set [Kaminski et al., J. Phys. Chem. 98, 13077 (1994)] was used to represent the n-alkanes, together with the TIP3P water model [Jorgensen et al., J. Chem. Phys. 79, 926 (1983)]. The approach of Beutler et al. [Chem. Phys. Lett. 222, 529 (1994)] was used to avoid singularities in nonbonded interaction potentials that can otherwise be problematical with this technique. Electrostatic interactions were treated using a cutoff radius of 0.9 nm, and a functional form that was shifted and scaled smoothly to zero. The values obtained for the solvation free energies were of similar accuracy to those from previously published simulations, but were systematically about 2 kJ mol−1 higher than experimental values. However, the calculated free energies of transformation for the re...

International Journal of Food Science & Technology, 2000

Chemistry and Physics of Lipids, 1975

Benzene solutions of purified egg lecithin, with small amounts of water added, have been examined... more Benzene solutions of purified egg lecithin, with small amounts of water added, have been examined by 60 MGz and 100 MHz NMR spectroscopy, infrared spectrophotometry and phase contrast microscopy. The transverse relaxation times of the water, N-methyl and O--H protons are dependent on water concentration. This dependence changes sharply for the water proton at a level of one water molecule per lecithin monohydrate molecule. These results do not fully agree with those reported by other workers. Four mathematical models are examined which could account for the behaviour of the water protons. Models which assume a constant transverse relaxation time for water protons above a level of one water molecule per lecithin molecule cannot predict the behaviour observed. It is sufficient to assume that water protons above this concentration have a single relaxation time which is a linear function of water concentration. The added water associates primarily with the phosphate in the lecithin head group. Above nine water molecules per lecithin monohydrate molecule free water is present in the system.

Advances in Colloid and Interface Science, 1992

... Titre du document / Document title. THE DRAINAGE OF AN AQUEOUS FILM BETWEEN A SOLID PLANE AND... more ... Titre du document / Document title. THE DRAINAGE OF AN AQUEOUS FILM BETWEEN A SOLID PLANE AND AN AIR BUBBLE. Auteur(s) / Author(s). FISHER LR ; HEWITT D. ;MITCHELL EE ; RALSTON J. ; WOLFE J. ; Revue / Journal Title. ...

Colloids and Surfaces, 1991

Global Policy

The world faces a multiplicity of global catastrophic risks (GCRs), whose functionality as indivi... more The world faces a multiplicity of global catastrophic risks (GCRs), whose functionality as individual and collective complex adaptive networks (CANs) poses unique problems for governance in a world that itself comprises an intricately interlinked set of CANs. Here we examine necessary conditions for new approaches to governance that consider the known properties of CANs—especially that small changes in one part of the system can cascade and amplify throughout the system and that the system as a whole can also undergo rapid, dramatic, and often unpredictable change with little or no warning.

Faraday discussions of the Chemical Society, 1986

The profile of the aqueous draining film between approaching hemispherical glycerol mono-oleate b... more The profile of the aqueous draining film between approaching hemispherical glycerol mono-oleate bilayers of radius 1 mm has been calculated from the reflectance of a focussed laser beam which could be scanned across the interaction zone. When the bilayers were brought together mechanically at fast approach rates (> 15 µm s–1), the draining aqueous film between the bilayers was thicker at the centre than at the boundary (the well known ‘dimpled’ configuration), while at approach rates below 1 µm s–1 the draining film was essentially flat. When the bilayers were driven together by osmotic swelling, drainage was dominated by passage of water through the bilayers. In some samples a small amount of a polar impurity produced electrostatic repulsion between the bilayers. We were thus able to observe the effect of electrostatic repulsion on dimple formation and drainage. Regardless of the presence or absence of electrostatic repulsion, the bilayers always fused when the distance of closest approach reached a critical value of (28.0 ± 0.5) nm. Fusion resulted in the formation of a new structure, with a single bilayer separating the two aqueous compartments.

MRS Proceedings, 1987

ABSTRACTResults of preliminary investigations on varying the adhesion and growth behaviour of ost... more ABSTRACTResults of preliminary investigations on varying the adhesion and growth behaviour of osteoblast-like cells on silicon are presented. Significant changes in growth behaviour are obtained by implanting oxygen or by growing a thermal oxide on the surface. The objective of the work is to modify tissue adhesion to materials used as prosthetic devices.

Annual Reports Section" C"(Physical …, 1999

... 62, Discussion following TP Galbraith and BA Wallace, Faraday Discuss., 1998, 111 . 63, MJ Su... more ... 62, Discussion following TP Galbraith and BA Wallace, Faraday Discuss., 1998, 111 . 63, MJ Sutcliffe, AH Smeeton, ZG Wo and RE Oswald, Faraday Discuss., 1998, 111, 259 . ... 69, MSP Sansom, C. Adcock and GR Smith, J. Struct. Biol., 1998, 121, 246 Article CAS . ...

Annual Reports Section "C" (Physical Chemistry), 1999