Salicylaldehyde-Cobalt(II)-Catalyzed C-H Alkoxylation of Indoles with Secondary Alcohols.

A straight and efficient protocol for the synthesis of hindered indole-ethers via C-H alkoxylation of indoles was developed by a cobalt-catalyzed cross-dehydrogenative coupling reaction with secondary alcohols. The selection of the salicylaldehyde-Co(II) catalyst enables the reaction to proceed under conditions without acid or base addition in the presence of limited alcohols. The protocol has broad substrate scope for both indole and secondary alcohols and exhibits good functional tolerance. The synthetic applications are proven by gram-scale reaction and further diversification of the product. Preliminary mechanistic investigations indicate that the activation of C-H bonds is not the rate-determining step of the reaction.

Inner membrane YfgM-PpiD heterodimer acts as a functional unit that associates with the SecY/E/G translocon and promotes protein translocation.

PpiD and YfgM are inner membrane proteins that are both composed of an N-terminal transmembrane segment and a C-terminal periplasmic domain. Escherichia coli YfgM and PpiD form a stable complex that interacts with the SecY/E/G (Sec) translocon, a channel that allows protein translocation across the cytoplasmic membrane. Although PpiD is known to function in protein translocation, the functional significance of PpiD-YfgM complex formation as well as the molecular mechanisms of PpiD-YfgM and PpiD/YfgM-Sec translocon interactions remain unclear. Here, we conducted genetic and biochemical studies using yfgM and ppiD mutants and demonstrated that a lack of YfgM caused partial PpiD degradation at its C-terminal region and hindered the membrane translocation of Vibrio protein export monitoring polypeptide (VemP), a Vibrio secretory protein, in both E. coli and Vibrio alginolyticus. While ppiD disruption also impaired VemP translocation, we found that the yfgM and ppiD double deletion exhibited no additive or synergistic effects. Together, these results strongly suggest that both PpiD and YfgM are required for efficient VemP translocation. Furthermore, our site-directed in vivo photocrosslinking analysis revealed that the tetratricopeptide repeat domain of YfgM and a conserved structural domain (NC domain) in PpiD interact with each other and that YfgM, like PpiD, directly interacts with the SecG translocon subunit. Crosslinking analysis also suggested that PpiD-YfgM complex formation is required for these proteins to interact with SecG. In summary, we propose that PpiD and YfgM form a functional unit that stimulates protein translocation by facilitating their proper interactions with the Sec translocon.

A synthetic transcription factor pair mimic for precise recruitment of an epigenetic modifier to the targeted DNA locus.

We developed an epigenetically active, cooperative DNA binding transcription factor platform assisted by cucurbit[7]uril (CB7) host-guest modules. This new type of molecule termed ePIP-HoGu not only mimics the operation of transcription factors as a pair but also recruits the epigenetic modifier to a particular DNA locus.

Enhanced Energetic Performances Based on Integration with the Al/PTFE Nanolaminates.

Integrating energetic materials on a chip has received great attention for its widely potential applications in the microscale energy consumption system, including electric initiation device. In this article, reactive Al/PTFE nanolaminates with periodic layer structure are prepared by magnetron sputtering, which consists of fuel Al, oxidant PTFE, and inert layer Al-F compound in a metastable system. The as-deposited Al/PTFE nanolaminates exhibit a significantly high energy output, and the onset temperature and the heat of reaction are 410 °C and 3034 J/g, respectively. Based on these properties, an integrated film bridge is designed and fabricated via integrating Al/PTFE nanolaminates with a Cu exploding foil, which exhibits enhanced energetic performances with more violent explosion phenomenon, larger quantities of ejected product, and higher plasma temperature in comparison with the Cu film bridge. The kinetic energy of flyers derived from the expansion of the Cu film bridge is also increased around 29.9% via integration with the Al/PTFE nanolaminates. Overall, the energetic performances can be improved substantially through a combination of the chemical reaction of Al/PTFE nanolaminates with the electric explosion of the Cu film bridge.

Reactive B/Ti Nano-Multilayers with Superior Performance in Plasma Generation.

In this study, reactive B/Ti nano-multilayers were fabricated by magnetron sputtering and the structure and chemical composition were confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy analyses. The periodic multilayer structure can be clearly visible, and the multilayer material is composed of B layers (amorphous), Ti layers (nano-polycrystalline), and intermixed reactants in a metastable system. The as-deposited B/Ti nano-multilayers exhibit a significantly high heat release of 3722 J/g, with an onset reaction temperature of 449 °C. On the basis of these properties, an integrated microigniter was designed and prepared by integration of the B/Ti nano-multilayers with a TaN film bridge for potential applications in plasma generation, and the electric ignition processes were investigated with discharge voltages ranging from 25 to 40 V. The integrated microigniter exhibits improved and stable ignition performances with a short burst time, high plasma temperature, and violent explosion phenomenon in comparison with the TaN film igniter. Overall, the plasma generation of the microigniter can be enhanced substantially by integration with the B/Ti nano-multilayers.