Papers by Keyword: Sol-Gel Titania

Abstract: Co-doping of nanosilver, carbon and nitrogen is done on titania to get improved photodegradation of pollutants when compared to single doping. Anion doping extends the absorption of TiO2 to the visible region; whereas noble metal NP doping prevents the recombination of photoinduced electrons and holes. Doped TiO2 prepared using sol gel method allows efficient dispersion of nano silver and thus enhances the photodegradability. X-ray Diffraction analysis shows the efficient dispersion of incorporated nano silver over anatase TiO2. The visible light absorption is confirmed from UV-Vis Diffuse Reflectance spectral studies. Photocatalytic activity is investigated by the degradation of methyl orange as a model pollutant. Efficient degradation in visible light shows the synergetic effect of carbon and nitrogen doping as well as nano silver loading on the performance of TiO2.

Abstract: Current epilepsy rates in Mexico are 4% (SERSAME-Health Ministry), of which 80% correspond to Temporal Lobe Epilepsy (TLE). Antiepileptic drug administration is systemic, meaning that 90% of the active agent is lost between administration and delivery to the epileptic focus in the brain. Severe toxic secondary effects may occur as a result. The present study is aimed at developing an alternative antiepileptic drug delivery system. In this study, a sol-gel nanostructured titania device, in which valproic acid (VPA) has been encapsulated. This is a nanoparticulate device, which is biocompatible with brain tissue. Stereotactic surgery was used to implant the reservoirs in the temporal lobe of Wistar rats, using chemical kindling, which was used to induce epilepsy. The reservoir was designed to release the drug at a constant rate over a period of at least one year. A functional study was performed on the efficiency of drug delivery in order to evaluate the effect on spontaneous and induced neuron electrical activity. A new discovery, which is presented here, shows that in the case of damaged brain tissue, as is the case in epilepsy, the accumulation of red globules, oxygen transportation results in the formation of calcium carbonate crystals which surround the epileptic focus. Because these crystals have a specific polarization, we propose to characterize their influence on the EEG using statistical methods. The electrical activity was measured by electroencephalography using 5 healthy rats without and 5 rats with an implanted VPA/device. Cerebral signals describe the complex behavior of the brain dynamics as a function of time. Fractal algorithms are sensitive to fluctuations and lead to the analysis and characterization of this kind of complex phenomena. A systematic study of these EEG’s was made in order to observe the variation of signals during seizures and on the controlled rate of release of VPA. We have estimated the Hurst exponent (H) to measure long range-dependence. Preliminary results show that for the control group, signal behavior is persistent (H>0.5), while for the epileptic group antipersistency was observed (H<0.5), with variations due seizure stages. During the protection period using VPA, preliminary results show that values tend to reach original behavior, as the crisis is stabilized.