Engineering n-p junction for photo-electrochemical hydrogen production.

The generation of hydrogen from water and sunlight offers a promising approach for producing scalable and sustainable carbon free fuels. One of the challenges of solar-to-fuel technology is the design of efficient, long-lasting and low-cost photocathodes, which are responsible for absorbing sunlight and driving catalytic hydrogen evolution. We report on the protection of a Cu/Cu2O/CuO photoelectrode against photocorrosion by a 200-300 nm-thick BaTiO3 perovskite layer, deposited using the sol-gel method. This photoelectrode mediates H2 production with a current density of ∼3.1 mA cm-2 at 0 V versus RHE under 3 Sun irradiation and in a pH = 6 aqueous electrolyte. While the unprotected Cu/Cu2O/CuO photoelectrodes show a rapid decay of activity, the BaTiO3-protected photoelectrodes exhibit ∼10% current decay over 20 min.

Morphine analgesia: enhancement by shock-associated cues.

Recent research has shown that rats exposed to repeated stress display enhanced morphine analgesia. This study examined the possible contribution of classically conditioned analgesia to this effect. First, drug-naive rats exposed to nine daily sessions of stress, each consisting of a single 45-s exposure to footshock, subsequently displayed enhanced analgesic responsiveness to morphine 1 and 10 days after stress (Experiments 1, 2, and 5). This enhancement was also observed in morphine-experienced rats 1 and 8 days after stress (Experiment 1). Second, the effect of footshock stress on morphine analgesia was found to be specific to the environment in which stress was administered (Experiments 2 and 3). Rats tested in the same distinctive environment in which stress was administered displayed enhanced morphine analgesia; rats shocked elsewhere did not differ from nonshocked controls (Experiment 2). Third, conditioned analgesia was found under the same conditions that yielded enhanced morphine analgesia (Experiments 2 and 4). Lastly, both this conditioned analgesia and the acute analgesia elicited by the footshock stressor were found to be attenuated by naloxone (Experiments 5 and 6). These data are consistent with the hypothesis that the enhanced morphine analgesia observed after repeated footshock stress reflects the contribution of an opioid mediated , conditioned analgesia elicited by cues formerly paired with the stressor.

Prior hot plate exposure enhances morphine analgesia in tolerant and drug-naive rats.

The associative model of morphine tolerance predicts that established tolerance should be attenuated, i.e., extinguished, by placebo injections in the former morphine injection environment. The present study examined the effect of placebo sessions, with and without accompanying nociceptive stimulation, on the extinction of analgesic tolerance. In Experiment 1, rats rendered tolerant to morphine displayed recovery of morphine's analgesic action only following placebo sessions including exposure to a painful hot plate surface (52.5 degrees C); placebo sessions on a cool plate (23-24 degrees C) failed to attenuate tolerance even though these placebo sessions more closely matched the stimulus conditions of tolerance acquisition. In Experiment 2, repeated hot plate exposures were similarly found to enhance morphine analgesia in drug-naive rats. These results question an extinction account of the effect of hot plate placebo sessions observed in Experiment 1. Instead, they suggest that nociceptive hot plate exposures, per se, are sufficient to enhance subsequent morphine analgesia.

Determination of nicotine in allergenic extracts of tobacco leaf by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) system has been developed for the determination of nicotine and cotinine in allergenic extracts of tobacco leaf. This analysis showed eight allergenic extracts of tobacco (leaf and Mix) to have markedly different nicotine patterns. Cotinine, a photodegradation product of nicotine, was not detected.