Ion current densities near 1 A cm at modest bias voltages (<200 mV) are reported for proton and deuteron transmission across single-layer graphene in polyelectrolyte-membrane (PEM)-style hydrogen pump cells. The graphene is sandwiched between two Nafion membranes and covers the entire area between two platinum-carbon electrodes, such that proton transfer is forced to occur through the graphene layer. Raman spectroscopy confirms that buried graphene layers are single-layer and relatively free of defects following the hot-press procedure used to make the sandwich structures. Area-normalized ion conductance values of approximately 29 and 2.1 S cm are obtained for proton and deuteron transport, respectively, through single-layer graphene, following correction for contributions to series resistance from Nafion resistance, contact resistance, etc. These ion conductance values are several hundred to several thousand times larger than in previous reports on similar phenomena. A ratio of proton to deuteron conductance of 14 to 1 is obtained, in good agreement with but slightly larger than those in prior reports on related cells. Potassium ion transfer rates were also measured and are attenuated by a factor of many thousands by graphene, whereas proton transfer is attenuated by graphene by only a small amount. Rates for hydrogen and deuterium ion exchange across graphene were analyzed using a model whereby each hexagonal graphene hollow site is assumed to transmit ions with a specific per-site ion-transfer self-exchange rate constant. Rate constant values of approximately 2500 s for proton transfer and 180 s for deuteron transfer per site through graphene are reported.

A family of silica molecular sieves with lamellar frameworks and hierarchical structure (denoted MSU-V) was assembled from homogeneous solutions of neutral H2N(CH2) n NH2 bolaamphiphiles (n = 12−22) as the structure directors and tetraethylorthosilicate as the inorganic precursor. Optimal lamellar order was observed for four as-synthesized and calcined (550 °C) mesostructures when they were assembled at the following reaction temperatures (T, °C) and surfactant/silica ratios (R) of T = 25 °C, R = 0.26 (C12); T = 45 °C, R = 0.20 (C16); T = 55 °C, R = 0.15 (C18); T = 55 °C, R = 0.11 (C22). MSU-V silica assembled from the short C12 alkyl chain bolaamphiphile exhibited gallery-confined micropores (1.3 nm), but the derivatives prepared from the longer C16−C22 diamines showed gallery-confined mesopores. As the alkyl chain length of the bolaamphiphile surfactant increased from C16 to C22, the size of the gallery-confined mesopores increased from 2.0 to 2.7 nm. The described synthetic strategy afforded hierarchical MSU-V structures with biomimetic multilamellar vesicular particle architectures. Distorted vesicular, plate, and spiral-ribbon shaped particles also were observed, particularly for the lamellar silica assembled from the C16 bolaamphiphile. The variation in morphologies was attributed to agitation effects during synthesis. MSU-V silica assembled from the C22 diamine was the least stable member of the series and partially decomposed upon calcination. Remarkably, surfactant removal by calcination did not affect the biomembrane-like, hollow disk morphology of the original as-synthesized C22 product. This bolaamphiphile assembly approach provides new opportunities for the preparation of lamellar mesoporous molecular sieves with hierarchical structures specifically tailored to applications as diverse as sorbents, catalysts, sensors, bone implants, and nanoscale devices.

We use molecular dynamics simulation to investigate polarizability anistropy relaxation in two polar liquids, methanol and acetonitrile, which have similar dielectric constants at room temperature, but are very different at the molecular level. Interaction-induced contribution to the polarizability is included using first-order perturbation theory and separated into a component which projects along the sum of molecular polarizability anistropies and relaxes through collective reorientation and a ‘‘collision induced’’ component which relaxes through other mechanisms involving mainly translational motion. We find that interaction-induced effects on the polarizability anisotropy time correlation are important on all relevant time scales, especially for the more polarizable acetonitrile. In methanol, even though most of the molecular polarizability is along the CO bond, we find that the OH bond dynamics make a substantial direct contribution to polarizability anisotropy relaxation. We compare our results to the experimentally determined nuclear portion of the optical Kerr effect response and discuss their implications for the use of this response in solvation dynamics theories. We find that the short-time optical Kerr response of acetonitrile is dominated by collision-induced polarizability dynamics, while librational orientational dynamics is the main contributor for methanol.

Photothermal therapy (PTT) is widely regarded as a promising technology for cancer treatment. Gold nanorods (GNRs), as excellent PTT agent candidates, have shown high-performance photothermal conversion ability under laser irradiation, yet two major obstacles to their clinical application are the lack of selective accumulation in the target site following systemic administration and the greatly reduced photothermal conversion efficiency caused by self-aggregating in aqueous environment. Herein, we demonstrate that tLyp-1 peptide-functionalized, indocyanine green (ICG)-containing mesoporous silica-coated GNRs (I-TMSG) possessed dual-function as tumor cells-targeting near-infrared (NIR) fluorescent probe and PTT agents. The construction of the nanostructure began with synthesis of GNRs by seed-mediated growth method, followed by the coating of mesoporous silica, the chemical conjugation of PEG and tLyp-1 peptide, and the enclosure of ICG as an NIR imaging agent in the mesoporous. The as-prepared nanoparticles could shield the GNRs against their self-aggregation, improve the stability of ICG, and exhibit negligible dark cytotoxicity. More importantly, such a theranostic nanocomposite could realize the combination of GNRs-based photothermal ablation under NIR illumination, ICG-mediated fluorescent imaging, and tLyp-1-enabled more easy endocytosis into breast cancer cells. All in all, I-TMSG nanoparticles, in our opinion, possessed the strong potential to realize the effective diagnosis and PTT treatment of human mammary cancer.

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