Encapsulated Copper-Based Phase-Change Materials for High-Temperature Heat Storage.

In this study, a copper-based capsule, encapsulated by a black alumina shell using a simple method, was developed for high-temperature heat storage over 1000 °C. The shell was filled with copper beads (diameter = ∼3 mm), the copper-aluminum (Cu-Al) atomized powder (particle size = 150 µm) was filled in the gap, and then it was heat-treated. This eventually formed a high-density, aluminum-rich network around the Cu beads in the shell. Morphological observations indicated that the corrosion of copper oxide (CuO) on the alumina shell was significantly reduced by mixing Al with Cu. When heat-treated in air at 1100 °C, Cu became CuO, which reacted with Al2O3 to form a new compound, CuAl2O4. Owing to this two-step reaction, the area around the hole provided at the top of the spherical shell gets sealed, thereby suppressing the flow of oxygen into the shell (self-sealing function). The mechanism of in situ sealing was detected using X-ray diffraction and scanning electron microscopy analyses. The Cu-(5-10%) Al capsule could endure a 400 h air exposure test at 1100 °C without leakage or cracking. A low weight increase ratio of 3.5% after the exposure revealed good oxidation resistance of the capsule, whereas the slight damage load change of the capsule after the exposure showed good mechanical stability. The results concluded that a Cu-(5-10%) Al capsule for high-temperature heat storage applications above 1000 °C can be fabricated by a simple process, and it demonstrates excellent durability during the long-term air exposure test. The data obtained in this study can be used as a reference for the design of packed beds in the future.

Bioactivation of morphine in human liver: isolation and identification of morphinone, a toxic metabolite.

Morphinone, identified in the bile of guinea pigs and rats given morphine, is a reactive electrophile and has the ability to bind to glutathione (GSH) and tissue macromolecules, leading to GSH depletion and cell damage. We previously demonstrated that the livers of various animal species are capable of forming morphinone from morphine. In this study, we examined whether the human liver can produce morphinone from morphine. HPLC analysis revealed that the incubation of morphine with the 9000xg supernatant of human liver in the presence of NAD(P) and 2-mercaptoethanol (ME) gave a peak corresponding to the synthetic morphinone-ME adduct (MO-ME), which is readily formed by a nonenzymatic reaction of morphinone with ME. The reaction product was isolated and was unambiguously identified as MO-ME using FAB-MS and NMR analyses in comparison with synthetic MO-ME. The conversion of morphine to morphinone required NAD(P), and NAD was a preferred cofactor over NADP. All the 9000xg supernatants from six human livers could produce morphinone at different rates, ranging from 30 to 120 nmol/g liver/30 min with NAD at pH 7.4. The enzyme activity responsible for the formation of morphinone from morphine was mainly localized in the microsomes. The microsomal enzyme activity was inhibited by steroids, lithocholic acid and indomethacin. Among these compounds, steroids with a 17beta-hydroxyl group almost completely depressed morphinone formation. In conclusion, the metabolic pathway of morphine to morphinone, a toxic metabolite, in human was shown for the first time in in vitro experiments.