Perfluorohexane

Abstract: Solid microspheres or hollow (i.e. gas or vapour filled) microcapsules, for example of amylodextrin are prepared by form-ing a shell from a water-soluble starch derivative around a solid or liquid core and subsequently removing the core. The core may be a volatile oil such as perfluorohexane. The microspheres or microcapsules may be made by an oil/water/oil double emulsion followed by chemical or heat hardening to render them water-insoluble. The microspheres can be used for nasal delivery systems and the microcapsules for echocardiography.

Abstract: Surface and interfacial tensions of dilute aqueous solutions of sodium perfluorobutyrate, sodium perfluorooctanoate, sodium perfluorodecanoate, sodium octyl sulfate, and sodium decyl sulfate at the air-water (a/w), hexane-water (h/w), and perfluorohexane-water (p-f-h/w) interfaces have been measured with the objective of determining the relative affinities for the interfaces at low degrees of adsorption. Up to approximately 2 dyn/cm the surface pressures were found to increase linearly with surfactant concentration (activity), in agreement with a thermodynamic model of adsorption. The free energies of adsorption, have been estimated by using the thermodynamic model. From these data the incremental changes in free energy of adsorption, ..delta.. free energy of adsorption values, on adding a-CH/sub 2/-group to the hydrocarbon chain and a-CF/sub 2/-group to the fluorocarbon chain have been calculated. The affinity of a hydrocarbon surfactant for the h/w interface is markedly higher than that for the a/w interface. A fluorocarbon surfactant at the p-f-h/w interface shows a much smaller increase in affinity as compared to the a/w interface. 31 references.

Abstract: Ultrasound contrast media comprising gaseous perfluoropentane and gaseous perfluorohexane are disclosed.

Abstract: In the present work, the boiling heat transfer coefficient (BHTC) and fluid flow characteristics of graphene oxide nanoplatelets (GONPs) nano-suspensions in an annular heat exchanger (AHEX) were experimentally investigated. The BHTC, pressure drop (PD) and the friction factor (FF) of the heat exchanger was quantified, and effects of various operating conditions including heat flux (HF), flow rate (FR), the temperature of the nano-suspension and the mass concentration (MC) of the GONPs on the HTC and the PD of the system was assessed. Results showed that by increasing the HF, the weight concentration of the GONPs, and the temperature of the working fluid, the BHTC of the system increases. Also, the presence of GONPs can augment the friction forces, viscosity, and, as a result, increase the PD and the FF of the system. For all the experiments, the BHTC of the system was more significant than water. A comparison between water-perfluorohexane and water- n-pentane nano-emulsions revealed that water-n pentane has better thermal performance and lower PD in comparison with perfluorohexane despite the presence of the GONPs within the bulk of the nano-emulsion.