Purpose: Perovskites are greatly used nowadays in many technological applications because of their high permittivity, more specifically in the form of aqueous solutions, for MRI dielectric shimming. In this study, full dielectric characterizations of highly concentrated CaTiO₃/BaTiO₃ water mixtures were carried out and new permittivity maxima was reached.Methods: Permittivity measurements were done on aqueous solutions from 0%v/v to dry powder. The permittivity dependence with pressure was investigated. Scanning electron microscopy images were performed on a few representative solutions. BaTiO₃ pressed pads of different thicknesses, permittivities, and distances to the head were compared in a 7T MRI scanner.Results: Perovskite aqueous mixtures undergo a pressure‐dependent phase transition in terms of permittivity, with increasing water content. A new relative permittivity maximum of 475 was achieved. Microscopic images revealed structural differences between phases. A improvement in the temporal lobe was obtained with thin, high permittivity BaTiO₃ head.Conclusions: This new preparation method allows improved pad geometry and placement, as a result of the high relative permittivity values achieved. This method has great significance for medical applications of MRI dielectric shimming, being easy to replicate and implement on a large scale. Magn Reson Med 79:1753–1765, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Asteroid Ceres, the only dwarf planet located in the inner solar system, shows unique surface mineralogy and geomorphology as observed by the Dawn mission. Of particular interest is understanding the role that upper regolith porosity plays in retaining volatiles and shaping Ceres’ surface. Unfortunately, Ceres’ near-surface porosity remains largely uncharacterized, compromising the ability to quantify volatile occurrence and identify the mechanisms for volatile retention at shallow depths, a topic of ongoing debate. Herein, we estimate Ceres’ shallow-subsurface porosity by reinterpreting existing S- and X-band Earth-based radar observations combined with dielectric laboratory measurements of analog materials that have been recently suggested by spectral observations from the Dawn VIR spectrometer and in the far-ultraviolet from the Hubble telescope. Contrary to previous assumptions, our results suggest that Ceres’ surface is more porous than the lunar regolith, with a bulk porosity ranging from ∼53% to 72% or even higher in the top meter of the regolith, as opposed to ∼39% to 50% for both bodies. The above suggests that Ceres’ regolith is on average 15% more porous than the Moon, hence explaining its higher potential for volatile retention. We propose that lofting and gradual redeposition of fine particles by avalanches, continuous micrometeorite bombardment, and localized volatile outgassing are possible mechanisms for generating a globally high-porosity regolith. In addition to Ceres’ proximity to the snowline of the early solar system, such a highly porous regolith may explain its efficiency at retaining volatiles at shallow depths into the present, as revealed by Dawn’s GRaND observations.

Hepatic steatosis may be caused by type 2 diabetes or obesity and is one of the origins of chronic liver disease. A non-invasive technique based on microwave propagation can be a good solution to monitor hepatic tissue pathologies. The present work is devoted to the dielectric permittivity measurements in healthy and fatty liver in the microwave range. A mouse model following normal and high sugar/glucose (HFS) diets was used. We demonstrated the change in the triglyceride and glucose concentration in the hepatic tissue of HFS diet mice. The difference in the dielectric permittivity of healthy and fatty liver was observed in the range from 100 MHz to 2 GHz. The dielectric permittivity was found to be 42 in the healthy tissue and 31 in the fatty liver tissue at 1 GHz. The obtained results demonstrate that dielectric permittivity can be a sensitive tool to distinguish between healthy and fatty hepatic tissue.

This article presents an easy way to measure frequency dependence of the complex permittivity and complex permeability for any kind of material from 10 MHz to 6 GHz, with temperature variation between the ambient temperature and 85°C. This work is based on a well-known transmission/reflection technique using a coaxial line equipped with a thermoregulation system to manage temperature variations in the sample confinement area. The paper underlines some effects which have to be taken into account with temperature variation. APU10 and cyclohexanol are presented as examples of solid and liquid reference materials.