An ultra-sensitive T 2-weighted MR contrast agent based on Gd3+ ion chelated Fe3O4 nanoparticles.

An ultra-sensitive T 2-weighted MR imaging contrast agent was prepared based on Fe3O4 nanoparticles and Gd3+ ions (Fe3O4@Gd). Amino modified Fe3O4 nanoparticles were conjugated to diethylenetriamine pentaacetic acid, and finally coordinated with Gd3+ ions. The nanoparticles had a uniform morphology with a size of 100 nm and a Gd/Fe mass ratio of 1/110. The r 2 (transverse relaxivity) of the Fe3O4 nanoparticles increased from 131.89 mM-1 s-1 to 202.06 mM-1 s-1 after coordination with Gd3+ ions. MR measurements showed that the aqueous dispersion of Fe3O4@Gd nanoparticles had an obvious concentration-dependent negative contrast enhancement. Hepatoma cells were selected to test the cytotoxicity and MR imaging effect. The application of Fe3O4@Gd nanoparticles as contrast agents was also exploited in vivo for T 2-weighted MR imaging of rat livers. All the results showed the effectiveness of the nanoparticles in MR diagnosis.

Ozone dissociation to oxygen affected by Criegee intermediate.

The detailed potential energy surfaces for the reactions of Criegee intermediate (CI, H2COO) and formaldehyde (H2CO) with ozone (O3) have been investigated at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311++G(2d,2p) level of theory, respectively. New alternative reaction mechanisms, to the one previously proposed (J. Phys. Chem. Lett. 2013, 4, 2525) have been found. The lower barrier of the new mechanism shows that it is easy for H2COO + O3 to dissociate to formaldehyde and oxygen. For the reactions of H2CO with O3 to produce H2COO and O2, we find relatively high energy barriers, which makes the ozone dissociation to oxygen unlikely to be catalyzed by CI.

[Measurement and comparison of Zn, Fe, Cu, Mn, Cr, Pb and Cd in rabbit liver of high-adipose group and normal group].

The objective of the present paper is to explore the experimental changes in the content of Zn, Fe, Cu, Mn, Cr, Pb and Cd in white rabbit liver with atherosclerosis disease. The method is to reproduce white rabbit liver with atherosclerosis disease by a high-fat diet, and then measure the Zn, Fe, Cu, Mn, Cr, Pb and Cd content with atomic absorption spectrometry. Results show that the Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in the fodders of the normal group are 137.6, 362.3, 14.39, 9.599 mg x kg(-1) and 159.3, 355.0, 290.0 microg x kg(-1), and 86.09, 277.1, 11.07, 5.366 mg x kg(-1) and 115.2, 286.0, 210.5 microg x kg(-1), in high-adipose group. It was concluded that Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in white rabbit liver decline, which may have something to do with the intake of foods and the abnormalities of lipoprotein metabolism.