The molar ratio of the FeCl3:FeCl2 should be about 2:1. Heat the mix to 70 °C, then raise the speed of stirring to about 7500 rpm and quickly add a solution of NH4OH (10 volume %). A dark precipitate  of nanoparticles of magnetite forms immediately.In both methods, the precipitation reaction relies on rapid transformation of acidic iron ions into the spinel iron oxide structure at pH 10 or higher. Controlling the formation of magnetite nanoparticles presents challenges: the reactions and phase transformations necessary for the creation of the magnetite spinel structure are complex. The subject is of practical importance because magnetite particles are of interest in bioscience applications such as magnetic resonance imaging (MRI), in which iron oxide magnetite nanoparticles potentially present a non-toxic alternative to the gadolinium-based contrast agents currently in use. However, difficulties in controlling the formation of the particles, still frustrate the preparation of superparamagnetic magnetite particles, that is to say: magnetite nanoparticles with a coercivity of 0 A/m, meaning that they completely lose their permanent magnetisation in the absence of an external magnetic field. The smallest values currently reported for nanosized magnetite particles is Hc = 8.5 A m−1, whereas the largest reported magnetization value is 87 Am2 kg−1 for synthetic magnetite.Pigment quality Fe3O4, so called synthetic magnetite, can be prepared using processes that use industrial wastes, scrap iron or solutions containing iron salts (e.g.
Chondroid lipomas are deep-seated, firm, yellow tumors that characteristically occur on the legs of women. They exhibit a characteristic genetic translocation t(11;16) with a resulting C11orf95-MKL2 fusion oncogene. : 625

See also
Lipoma
Skin lesion
List of cutaneous conditions

References


== External links ==