Abstract: A nanofluid includes a base fluid and multiwall carbon nanotubes (MWCNTs) dispersed in the base fluid. The MWCNTs have an outer surface provided with polar functional groups. The outer surface has decorated portions covered with nanoparticles and undecorated portions where the polar functional groups are exposed. A method prepares a nanofluid. In a first step, MWCNTs are grown on substrates by catalyst-free thermal chemical vapor deposition. In the following step, the MWCNTs' outer surface is functionalized to form polar functional groups covalently bonded thereto. Then, nanoparticles are deposited on the MWCNTs' outer surface such that the outer surface has decorated portions covered with the nanoparticles, while leaving undecorated portions where the polar functional groups are exposed. The resulting nanoparticle-decorated functionalized MWCNTs are then detached from the substrates and dispersed in a base fluid.

Abstract: A structure for attaching to a substantially vertical ferromagnetic surface comprises a flexible magnetized sheet and attached to the sheet, a holder for holding, supporting, or restraining one or more objects. In one preferred embodiment the holder is formed of semi-rigid material.