We report on DNA translocations through nanopores created in graphene membranes. Devices consist of 1-5 nm thick graphene membranes with electron-beam sculpted nanopores from 5 to 10 nm in diameter. Due to the thin nature of the graphene membranes, we observe larger blocked currents than for traditional solid-state nanopores. However, ionic current noise levels are several orders of magnitude larger than those for silicon nitride nanopores. These fluctuations are reduced with the atomic-layer deposition of 5 nm of titanium dioxide over the device. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor. Use of graphene as a membrane material opens the door to a new class of nanopore devices in which electronic sensing and control are performed directly at the pore.

We report broadband visible photoluminescence from solid graphene oxide, and modifications of the emission spectrum by progressive chemical reduction. The data suggest a gapping of the two-dimensional electronic system by removal of π-electrons. We discuss possible gapping mechanisms, and propose that a Kekule pattern of bond distortions may account for the observed behavior.

Graphene oxide membranes up to 2000 microm(2) in size can be synthesized with 90% yield in bulk quantities through a microwave-assisted chemical method. Membranes are readily visualized on an oxidized silicon substrate, which enables efficient fabrication of electronic devices and sensors. Field effect transistors made of the membrane show ambipolar behavior, and their conductivity is significantly higher than previously reported values.

Experiments have shown that graphene-supported Ni-single atom catalysts (Ni-SACs) provide a promising strategy for the electrochemical reduction of CO 2 to CO, but the nature of the Ni sites (Ni-N 2 C 2 , Ni-N 3 C 1 , Ni-N 4) in Ni-SACs has not been determined experimentally. Here, we apply the recently developed grand canonical potential kinetics (GCP-K) formulation of quantum mechanics to predict the kinetics as a function of applied potential (U) to determine faradic efficiency, turn over frequency, and Tafel slope for CO and H 2 production for all three sites. We predict an onset potential (at 10 mA cm −2) U onset = −0.84 V (vs. RHE) for Ni-N 2 C 2 site and U onset = −0.92 V for Ni-N 3 C 1 site in agreement with experiments, and U onset = −1.03 V for Ni-N 4. We predict that the highest current is for Ni-N 4 , leading to 700 mA cm −2 at U = −1.12 V. To help determine the actual sites in the experiments, we predict the XPS binding energy shift and CO vibrational frequency for each site.

Transient receptor potential channels (TRPs) as cellular sensors are thought to function as tetramers. Yet, the molecular determinants governing homotetramerization of heat-activated TRPV1-4 remain largely elusive. In this study, we identified a segment comprising 20 amino acids after the known TRPlike domain in the channel C-terminus that functions as a tetrameric assembly domain (TAD). Purified recombinant C-terminal proteins of TRPV1-4, but not the N-terminus, mediated the protein-protein interaction in in vitro pull-down assay. Western blot analysis combined with confocal calcium imaging further demonstrated that the TAD exerted robust dominant-negative effect on wildtype TRPV1. When fused with membrane-tethered peptide Gap43, the TAD blocked the formation of stable homomultimers, and removal of the TAD from the full length TRPV1 resulted in nonfunctional channels. Calcium imaging and current recording showed that deletion of the TAD in a poreless TRPV1 mutant subunit suppressed its dominantnegative phenotype, confirming the involvement of the TAD in assembly of functional channels. Our findings suggest that the C-terminal TAD in heat-activated TRPV1-4 channels functions as a conserved domain that mediates a direct subunitsubunit interaction for tetrameric assembly.

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The properties of van der Waals (vdW) materials often vary dramatically with the atomic stacking order between layers, but this order can be difficult to control. Trilayer graphene (TLG) stacks in either a semimetallic ABA or a semiconducting ABC configuration with a gate-tunable band gap, but the latter has only been produced by exfoliation. Here we present a chemical vapor deposition approach to TLG growth that yields greatly enhanced fraction and size of ABC domains. The key insight is that substrate curvature can stabilize ABC domains. Controllable ABC yields ~59% were achieved by tailoring substrate curvature levels. ABC fractions remained high after transfer to device substrates, as confirmed by transport measurements revealing the expected tunable ABC band gap. Substrate topography engineering provides a path to large-scale synthesis of epitaxial ABC-TLG and other vdW materials.