A Proposed Computed Tomography Contrast Agent Using Carboxybetaine Zwitterionic Tantalum Oxide Nanoparticles: Imaging, Biological, and Physicochemical Performance.

Objectives: The aim of this study was to produce and evaluate a proposed computed tomography (CT) contrast agent based on carboxybetaine zwitterionic (CZ)-coated soluble tantalum oxide (TaO) nanoparticles (NPs). We chose tantalum to provide superior imaging performance compared with current iodine-based clinical CT contrast agents. We developed the CZ coating to provide biological and physical performance similar to that of current iodinated contrast agents.

Spatial and angular distribution of light incident on coatings using Mie-scattering Monte Carlo simulations.

We show the results of Mie-scattering Monte Carlo models developed to simulate the optical properties of light incident on particle-containing coatings. The model accommodates mixtures of particles with different sizes and complex refractive indices, enabling the simulation of formulations, including pigments. The simulation tracks trajectories of photons as they propagate through the turbid medium, calculating both angular and spatial light intensity distributions.

Comparison of H-H versus Si-H sigma-Bond Coordination and Activation on 16e Metal Fragments. Organosilane, N(2), and Ethylene Addition to the Agostic Complex W(CO)(3)(PR(3))(2) and Dynamic NMR Behavior of the Latter.

Variable-temperature (31)P{(1)H} NMR spectroscopy of the agostic complexes M(CO)(3)(PCy(3))(2) (M = Mo, W) indicates dynamic behavior as evidenced by collapse below -20 degrees C of a singlet to an AB signal plus a shifted singlet. The inequivalency of the phosphines is possibly due to the presence of conformational isomers resulting from hindered rotation of the M-P bond or, less likely, a geometric isomer with pseudo-cis PCy(3) ligands. Further studies on the coordination chemistry of W(CO)(3)(PR(3))(2) (R = iPr, Cy) were performed.