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Dehydro-Diels—Alder (DDA) reaction is a textbook reaction for preparing six-membered rings in solution but is scarcely seen in solid-state synthesis. In this work, using multiple characterization techniques, we demonstrate that the bowl-shaped clusters C18Te3Br4(Bu-O)6 might experience a DDA reaction at room temperature and high pressure between 5.5 and 7.4 GPa. Above 17.0 GPa, it is found that the bonding conversion from the intramolecular sp2 to the intermolecular sp3 occurred, in the form of pressure-induced diamondization. The recovered samples from 20.0 and 36.1 GPa showed incomplete reversibility, while the decompression-induced graphitization of glassy carbon was observed during decompression from 46.5 GPa. The electrochemical impedance spectroscopy results indicated that the transport properties changed from grain boundary dominant to grain dominant due to the DDA reaction and the grain boundary effect disappeared as the intermolecular sp3 bonding building-up and carrier transmission channel formation above 17.0 GPa. The results in this study open a new route to construct the crystalline carbon materials with different transport properties. [ABSTRACT FROM AUTHOR]

In the fermentative process using Saccharomyces cerevisiae to produce bioethanol, the performance of cells is often compromised by the accumulation of ethanol. However, the mechanism of how S. cerevisiae responds against ethanol stress remains elusive. In the current study, S. cerevisiae cells were cultured in YPD (yeast extract - peptone - dextrose) medium containing various concentrations of ethanol (0%, 2.5%, 5%, 7.5%, 10%, and 15% ( v/ v)). Compared with the control group without ethanol, the mean cell volume of S. cerevisiae decreased significantly in the presence of 7.5% and 10% ethanol after incubation for 16 h ( P < 0.05), and in the presence of 15% ethanol at all 3 sampling time points (1, 8, and 16 h) ( P < 0.05). The exposure of S. cerevisiae cells to ethanol also led to an increase in malonyldialdehyde content ( P < 0.05) and a decrease in sulfhydryl group content ( P < 0.05). Moreover, the observations through transmission electron microscopy enabled us to relate ultrastructural changes elicited by ethanol with the cellular stress physiology. Under ethanol stress, the integrity of the cell membrane was compromised. The swelling or distortion of mitochondria together with the occurrence of a single and large vacuole was correlated with the addition of ethanol. These results suggested that the cell membrane is one of the targets of ethanol, and the degeneration of mitochondria promoted the accumulation of intracellular reactive oxygen species. [ABSTRACT FROM AUTHOR]