The solubility of tris(pentane-2,4-dionato)chromium(III) (Cr(acac)3) in supercritical carbon dioxide (SC-CO2) with and without modifiers was investigated by UV–vis spectrophotometry. The influence of some polar and nonpolar modifiers, such as methanol, ethanol, 2,2,2-trifluoroethanol (TFE), acetone, chloroform, and benzene, was studied by changing the temperature, pressure, and concentration of the modifiers. Alcohols, particularly TFE, demonstrated a large solubility enhancement of Cr(acac)3 among these modifiers. In contrast, acetone having a relatively larger polarity gave a lower enhancement effect than chloroform and benzene. The measurement of the IR absorption spectra of TFE in the presence of Cr(acac)3 in SC-CO2 suggested that a drastic solubility enhancement of Cr(acac)3 upon the addition of TFE could be ascribed to the formation of the stable Cr(acac)3–TFE complex through hydrogen bonding. The association constants of Cr(acac)3 with TFE in SC-CO2 could be determined from the relationship of the solubility enhancement against the TFE concentration.
The purpose of this study was to evaluate the enhancement profile of 1.0M gadobutrol (high concentration: HC) in comparison to 0.5M gadopentetate dimeglumine and gadoterate meglumine (low concentration: LC) in dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of prostate. In total, 48 patients who were diagnosed with prostate cancer by radiologist were included. Each patient was examined after intravenous injection of 0.1 mmol/kg body weight contrast agent with flow rate of 1.5 (HC) or 3.0 mL/s (LC). Circular regions of interest were placed at prostate cancer (PCa) and normal peripheral zone (normal PZ) in DCE-MRI. The enhancement curves were calculated as a relative enhancement. Statistical analysis was performed by Mann-Whitney U test (p<0.05 were considered significant). As a result, the enhancement at first phase of HC was significantly lower compared with LC in PCa (HC, 0.47; LC, 0.85; p=0.029), and in normal PZ (HC, 0.12; LC, 0.22; p=0.033). The enhancement of HC in PCa was significantly higher compared with LC at late phase. Although not significant, a similar tendency was observed in normal PZ. The present study suggested that the enhancement profile with HC was higher at late phase but the rise of the enhancement curve with HC tended to be delayed.
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