Colossal dielectric constants in transition-metal oxides

Many transition-metal oxides show very large ("colossal") magnitudes of the dielectric constant and thus have immense potential for applications in modern microelectronics and for the development of new capacitance-based energy-storage devices. In the present work, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant, especially emphasising effects generated by external and internal interfaces, including electronic phase separation. In addition, we provide a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related systems, which is today's most investigated material with colossal dielectric constant. Also a variety of further transition-metal oxides with large dielectric constants are treated in detail, among them the system La2-xSrxNiO4 where electronic phase separation may play a role in the generation of a colossal dielectric constant.Comment: 31 pages, 18 figures, submitted to Eur. Phys. J. for publication in the Special Topics volume "Cooperative Phenomena in Solids: Metal-Insulator Transitions and Ordering of Microscopic Degrees of Freedom

Subjective effects of 'Salvia Divinorum': LSD- or Marijuana-like?

'Salvia divinorum' is a naturally occurring psychedelic considered to be one of the most potent hallucinogens found to date. The few behavioral studies conducted conclude that Salvia's effects may be similar to traditional psychedelics, which is noteworthy because Salvia acts via a unique molecular mechanism as a kappa opioid receptor agonist. One hundred and ninety-three participants, including 34 Salvia users, were asked to till out a series of questionnaires related to general drug use, personality characteristics, demographics and their experiences with Salvia. Salvia users were found to differ from nonusers on personality characteristics and reported consuming significantly more alcohol than nonusers. In addition, although Salvia users rated their hallucinogenic experiences as similar to those seen in previously published reports, the majority likened their experiences as most sintilar to marijuana instead of more traditional psychedelics. Low scores on the ARCI LSD subscale confirmed this finding and call into question the reigning theory of LSD-like subjective effects elicited by Salvia