The effects of titanium nanoparticles on enzymatic and non-enzymatic biomarkers in female Wistar rats.

Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in industry, pharmacy, medicine, and food sectors. Therefore, this study deals with the effects of TiO2 NPs in female rats following oral administration in differing doses for 14 days (0, 0.5, 5, and 50 mg/kg b.w./d). The response of enzymatic biomarkers (Na,K-ATPase, Mg-ATPase, and AChE) was measured in the brain, kidney, and small intestine, while non-enzymatic biomarker levels, such as different forms of glutathione (GSH) and thiobarbituric acid reactive substances (TBARSs) were measured in the liver. The images of the tissues were obtained using a transmission electron microscope (TEM) to demonstrate TiO2 NP accumulation. Data showed that brain AChE activity decreased at all TiO2 NP doses, though brain ATPase activities increased. However, ATPase activities in the intestine and kidney did not change significantly. Levels of GSH forms did not change significantly, though there was a significant decrease in TBARS level at the highest NP dose. TEM images demonstrated that TiO2 NPs accumulated in a dose-dependent manner in the tissues. Data emphasized that the brain was the most sensitive organ against the effects of TiO2 NPs. This study suggests the need for further studies to evaluate better the toxic effects of TiO2 NPs.

Acceptor formation in Mg-doped, indium-rich GaxIn1-xN: evidence for p-type conductivity.

We report on the Mg-doped, indium-rich GaxIn1-xN (x < 30). In the undoped material, the intrinsic electron density is very high and as a result there is no detectable photoconductivity (PC) signal within the range of temperatures of 30 150 K, is determined by the longitudinal-optical phonon scattering together with the thermal regeneration of non-equilibrium minority carriers from traps with an average depth of 103 ± 15 meV. This value is close to the Mg binding energy in GaInN. The complementary measurements of transient photoluminescence at liquid He temperatures give the e-A0 binding energy of approximately 100 meV. Furthermore, Hall measurements in the Mg-doped material also indicate an activated behaviour with an acceptor binding energy of 108 ± 20 meV.