Co-precipitation is by far the most common synthesis for magnetic iron oxide nanoparticles (IONPs), as cheap and environmentally friendly precursors and simple experimental procedures facilitate IONP production in many labs. Optimising co-precipitation syntheses remains challenging however, as particle formation mechanisms are not well understood. This is partly due to the rapid particle formation (within seconds) providing insufficient time to characterise initial precipitates. To overcome this limitation, a flow chemistry approach has been developed using steady-state operation to "freeze" transient reaction states locally. This allowed for the first time a comprehensive analysis of the early stages of co-precipitation syntheses via in-situ Small Angle X-ray Scattering and in-situ synchrotron X-Ray Diffraction. These studies revealed that after mixing the ferrous/ferric chloride precursor with the NaOH base solution, the most magnetic iron oxide phase forms within 5 s, the particle size changes only marginally afterwards, and co-precipitation and agglomeration occur simultaneously. As these agglomerates were too large to achieve colloidal stability via subsequent stabiliser addition, co-precipitated IONPs had to be de-agglomerated. This was achieved by adding the appropriate quantity of a citric acid solution which yielded within minutes colloidally stable IONP solutions around a neutral pH value. The new insights into the particle formation and the novel stabilisation procedure (not requiring any ultra-sonication or washing step) allowed to design a multistage flow reactor to synthesise and stabilise IONPs continuously with a residence time of less than 5 min. This reactor was robust against fouling and produced stable IONP solutions (of ~ 1.5 mg particles per ml) reproducibly via fast mixing (< 50 ms) and accurate temperature control at large scale (> 500 ml/h) for low materials cost.

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Purpose: The localized heating of magnetic nanoparticles (MNPs) via the application of time-varying magnetic fieldsa process known as magnetic field hyperthermia (MFH)can greatly enhance existing options for cancer treatment; but for broad clinical uptake its optimization, reproducibility and safety must be comprehensively proven. As part of this effort, the quantification of MNP heatingcharacterized by the specific loss power (SLP), measured in W/g, or by the intrinsic loss power (ILP), in Hm 2 /kgis frequently reported. However, in SLP/ILP measurements to date, the apparatus, the analysis techniques and the field conditions used by different researchers have varied greatly, leading to questions as to the reproducibility of the measurements. Materials and Methods: An interlaboratory study (across N = 21 European sites) of calorimetry measurements that constitutes a snapshot of the current state-of-the-art within the MFH community has been undertaken. Identical samples of two stable nanoparticle systems were distributed to all participating laboratories. Raw measurement data as well as the results of in-house analysis techniques were collected along with details of the measurement apparatus used. Raw measurement data was further reanalyzed by universal application of the corrected-slope method to examine relative influences of apparatus and results processing. Results: The data show that although there is very good intralaboratory repeatability, the overall interlaboratory measurement accuracy is poor, with the consolidated ILP data having standard deviations on the mean of ca. ± 30% to ± 40%. There is a strong systematic component to the uncertainties, and a clear rank correlation between the measuring laboratory and the ILP. Both of these are indications of a current lack of normalization in this field. A number of possible sources of systematic uncertainties are identified, and means determined to alleviate or minimize them. However, no single dominant factor was identified, and significant work remains to ascertain and remove the remaining uncertainty sources. Conclusion: We conclude that the study reveals a current lack of harmonization in MFH characterization of MNPs, and highlights the growing need for standardized, quantitative characterization techniques for this emerging medical technology.

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Single crystals of the ternary semiordered alloys UFe x Al 12Ϫx with xϭ3. 8, 4.0, 4.2, 4.5, 4.7, 5.0, 5.5, and 5.8, were prepared, and found to crystallize in the tetragonal ThMn 12 -type structure ͑space group I4/mmm͒. Studies of monocrystalline and polycrystalline samples of these materials, by ac susceptibility, magnetization, and 57 Fe Mössbauer spectroscopy, show two magnetic transitions in the range of 4.0ϽxՇ4.7, where only a single transition has been previously reported for polycrystalline materials. These measurements yield the magnetic phase diagram of this system, extending the magnetic structures of single crystal UFe 4 Al 8 , determined by ͑unpolarized and polarized͒ neutron diffraction, of polycrystalline UFe 5 Al 7 , determined elsewhere by neutron diffraction, and of single crystal UFe 5.8 Al 6.2 , determined by magnetization. The four magnetic regions, identified in the magnetic phase diagram, and their proposed magnetic structures, are discussed.