Anxiolytic effects of ketamine in animal models of posttraumatic stress disorder.

This study investigated the effectiveness of ketamine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, in alleviating the enhanced anxiety and fear response in both a mouse model of PTSD induced by inescapable electric foot shocks and a rat model of PTSD induced by a time-dependent sensitization (TDS) procedure. First, we evaluated the effect of ketamine on behavioral deficits in a mouse model of PTSD that consisted of foot shocks followed by three situational reminders. Our results showed that the aversive procedure induced several behavioral deficiencies, such as increased freezing behavior and anxiety, as well as reduced time spent in an aversive-like context, which were reversed by repeated treatment with ketamine. The effect of ketamine on behavioral changes after exposure to TDS was also investigated, and the levels of brain-derived neurotrophic factor (BDNF) in the hippocampus were measured. The results revealed that after TDS, the rats showed a significant increase in contextual freezing and a decrease in the percentage of time spent in and numbers of entries into open arms in the elevated plus maze test. As a positive control drug, sertraline (Ser, 15 mg/kg, i.g.), a selective serotonin reuptake inhibitor (SSRI) ameliorated these behavioral deficits. These behavioral effects were mimicked by chronic ketamine treatment. Furthermore, ketamine normalized the decreased BDNF level in the hippocampus in post-TDS rats. Taken together, these results suggest that ketamine exerts a therapeutic effect on PTSD that might be at least partially mediated by an influence on BDNF signaling in the hippocampus.

The effect of optical properties on photovoltaic performance in dye-sensitized TiO2 nanocrystalline solar cells.

In this study, well-crystallized TiO2 nanoparticles with average size of -20 nm were synthesized by hydrolysis of titania salt in aqueous medium. The effect of the optical properties of the obtained titania particles based thin films with different thickness on the photovoltaic performance of dye-sensitized solar cells were investigated. Differential thermal analysis/thermo-gravimetric analysis, scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterize the morphology, structure and crystal formation of the obtained samples. The optical properties such as reflectance and transmittance of the photoanodes with different thickness were systematically investigated. The reflectance property increased with increasing the film thickness, however, the transmittance property showed the opposite way. The improved scattering property with increasing the film thickness facilitated efficient utilization of solar spectrum, which was verified by incident photon-to-current conversion efficiency. The maximum energy conversion efficiency of 5.0% was achieved on photoelectrode film with 17.8 microm.

Improvement of dye-sensitized solar cells' performance through introducing suitable heterocyclic groups to triarylamine dyes.

Dye-sensitized solar cells are currently under intense academic and industrial investigation, owing to their great potential to serve as a low-cost alternative to existing photovoltaic technologies. This paper puts forward a method, which adopts heterocyclic substituted triarylamine units as electronic donor moieties, to design triarylamine dyes for efficient dye-sensitized solar cells. Three novel triarylamine dyes named TTC101, TTC102 and TTC103, were synthesized economically through modification of the structure of a simple triarylamine dye (TC105) using three kinds of heterocyclic groups (4-pyridyl, 2-thienyl and 1-pyrazolyl). The crystal structure of TTC103 indicates that the heterocyclic groups would partly delocalize the positive charge after photooxidation. The overall solar-to-electrical energy conversion efficiencies (η) of TTC102 and TTC103 are 4.92% and 5.21% respectively under AM1.5G irradiation, reaching ∼82.3% and ∼77.7% of a N719-based reference cell under the same conditions. Besides, the energy conversion efficiencies (η) of TTC102 and TTC103 are 1.29 and 1.37 times the efficiency of TC105 respectively. All of the results above demonstrate that photovoltaic performance can be improved by introducing suitable heterocyclic groups to triarylamine dyes. A series of properties were investigated to explain the results, with a special emphasis on the geometric structures, energetics, and charge transfer processes at the dye/titania/electrolyte interface.