In this work we present a systematic evaluation of the potential of combining dielectric materials with an array of electric dipoles for MRI. Design parameters include the permittivity and length of a dielectric sleeve, as well as the dipole length and position of the tuning inductors. Results show that the combined approach improves transmit efficiency and SNR by ~10 to 15 % compared to an optimized dipole array without dielectric sleeve. The resulting induced current densities reflect an improved correspondence with the ideal current pattern, which explains the gains in performance.@en

MRI at high fields requires new approaches to RF coil design to maximize RF performance. Over the past years, various technologies have been developed, ranging fromactive control via parallel RF transmission (pTx), to passive approaches using dielectric materials. Previous work also indicates that the combination of both can yield furtherimprovements.1,2 However, the analysis of a dielectric shim in resonant coil structures such as surface arrays can involve long simulation times due to mutual coupling. Thisimpedes a constructive analysis on the design of the dielectric in such scenarios.A domain decomposition method has previously been presented which reduces the computational domain to that of the dielectric shim, allowing for much faster evaluation of itseffect.3 This approach is especially powerful in a decoupled scenario in which the coil’s current distribution is minimally affected by the dielectric. In this work, we extend thedomain decomposition method using circuit co-simulation techniques to account for tuned coil models as well as array configurations. Examples are shown for a tuned 7T birdcageanalysis and a four-channel dipole array design study.@en

To evaluate the performance of zeolite-supported carbon-doped TiO2 composite catalysts toward target pollutants under solar light irradiation, the adsorption and photocatalytic degradation of 18 pharmaceuticals and pesticides with distinguishing features (molecular size and volume, and photolysis) were investigated using mordenite zeolites with SiO2/Al2O3 ratios of 18 and 240. Different quantities of carbon-doped TiO2 were coated on the zeolites, and then the finished composite catalysts were tested in demineralized, surface, and hospital wastewater samples, respectively. The composite photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, and surface area and porosity analyses. Results showed that a dispersed layer of carbon-doped TiO2 is formed on the zeolite surface; this layer blocks the micropores of zeolites and reduces their surface area. However, these reductions did not significantly affect adsorption onto the zeolites. Our results demonstrated that zeolite-supported carbon-doped TiO2 systems can effectively degrade 18 pharmaceuticals and pesticides in demineralized water under natural and simulated solar light irradiation. In surface and hospital wastewaters, zeolite-supported carbon-doped TiO2 systems present excellent anti-interference capability against radical scavengers and competitive organics for pollutants removal, and higher pollutants adsorption on zeolites evidently enhances the removal rate of target pollutants in surface and hospital wastewater samples with a complicated matrix. @en