Dielectric properties of muscle and adipose tissue-mimicking solutions for microwave medical imaging applications.

The aim of the present study was to synthesize mixture solutions which can accurately mimic the dielectric properties of biological tissues, specifically muscle and adipose tissues between 500 MHz and 50 GHz. Mixtures utilizing concentrations of bovine serum albumin (BSA) dissolved in phosphate buffered saline (PBS) and Ringer's solutions were synthesized to mimic in vivo and ex vivo muscle tissues. Solutions consisting of concentrations of peanut oil and Triton X-100 (TX) in PBS and Ringer's solutions were also synthesized to mimic in vivo and ex vivo adipose tissue. Results were then analysed and compared to measured dielectric properties of in vivo and ex vivo biological tissues from another previous study. Good agreement with said dielectric property measurements were obtained since the solutions from this study yielded low RMSE and RMSRE values. This implied that such solutions can be utilized in the construction of human body phantoms for narrowband and ultra-wideband microwave devices for near field breast cancer imaging.

Experimental charge-density study on the nickel(II) coordination complex [Ni(H3L)][NO3][PF6] [H3L = N,N',N''-tris(2-hydroxy-3-methylbutyl)-1,4,7-triazacyclononane]: a reappraisal.

The experimental charge density in the title complex has been re-examined. The original work, reported some 8 years ago [Smith et al. (1997). J. Am. Chem. Soc. 119, 5028-5034], was undertaken using a very early version of the XD software, which contained serious programming errors. A re-refinement, using the original data and a recent version of the XD software, shows that many of the unusual aspects of this earlier study are artefacts due to these programming errors. The topological properties of the newly obtained experimental density compare well with those calculated from a theoretical DFT (density-functional theory) UHF-SCF (unrestricted Hartree Fock-self-consistent field) density. This report corrects several erroneous conclusions regarding the charge density in the title complex--in particular, the highly unusual diffuse Laplacian distribution about the Ni atom, and the trifurcated bond path from the Ni atom to the alcohol oxygen donor atoms are no longer observed. An examination of a range of topological properties of the metal-ligand bonds leads to the conclusion that the Ni-N and Ni-O bonds have an intermediate character, with a significant shared interaction, but with a substantial ionic component. This new study also reveals a previously unrecognized intramolecular H...H interaction in the macrocyclic ligand.