Graphene-confined single Fe atoms, screened out from a series of 3d transition metals (Mn, Fe, Co, Ni, and Cu), were used as an efficient non-precious catalyst to directly convert methane to C1 oxygenated products at room temperature. The unique O-FeN 4 -O structure formed in graphene can readily activate the C-H bond of methane along a radical pathway with a low reaction energy barrier.

Coordination between plant height and xylem traits is aligned with habitat aridity across the Earth’s terrestrial biomes.

The application of THz to medical imaging is experiencing a surge in both interest and federal funding. A brief overview of the field is provided along with promising and emerging applications and ongoing research. THz imaging phenomenology is discussed and tradeoffs are identified. A THz medical imaging system, operating at ~525 GHz center frequency with ~125 GHz of response normalized bandwidth is introduced and details regarding principles of operation are provided. Two promising medical applications of THz imaging are presented: skin burns and cornea. For burns, images of second degree, partial thickness burns were obtained in rat models in vivo over an 8 hour period. These images clearly show the formation and progression of edema in and around the burn wound area. For cornea, experimental data measuring the hydration of ex vivo porcine cornea under drying is presented demonstrating utility in ophthalmologic applications.

A facile method based on microwave-assisted solvothermal process has been developed to synthesize flowerlike MgO precursors, which were then transformed to MgO by simple calcinations. All the chemicals used (magnesium nitrate, urea, and ethanol) were low cost and environmentally benign. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, and N(2) adsorption-desorption methods. These flowerlike MgO nanostructures had high surface area and showed superb adsorption properties for Pb(II) and Cd(II), with maximum capacities of 1980 mg/g and 1500 mg/g, respectively. All these values are significantly higher than those reported on other nanomaterials. A new adsorption mechanism involving solid-liquid interfacial cation exchange between magnesium and lead or cadmium cations was proposed and confirmed.

The effects of poly(vinylidene fluoride) (PVDF) component on the crystallization kinetics, crystalline structure, phase transition, and morphology of polymorphic poly(butylene adipate) (PBA) in their miscible PVDF/PBA binary blends have been investigated. The polymorphism of PBA can be regulated upon blending with PVDF. The incorporated PVDF faciliates the formation of PBA α-crystal, which is probably attributed to the thermodynamic and kinetic contributions. From the crystallization kinetics, it was found that a small amount of PVDF acts as a nucleating agent and can accelerate the crystallization of PBA, while a large amount of PVDF hinders the crystallization of PBA due to the confinement effect. In addition, the addition of PVDF greatly accelerates the β- to α-form phase transition of PBA upon annealing the PBA β-form at higher tmeperataure (48 °C). However, the large amount of PVDF decelerates the phase transition to a certain extent. The possible reasons for these phenomena were also proposed.

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The effect of graphite oxide (GO) as the enforcing filler on the properties of poly(e-caprolactone) (PCL) was investigated in this study. Through the introduction of GO, the Young's modulus of PCL was increased from 340 to 1000 MPa, and the tensile strength of PCL was increased from 15 to 26 MPa. Furthermore, the interlayer distance of GO (0.6 nm) was found to expand to 1.1 nm in the PCL/GO composite, which indicated the intercalation of the PCL chain into the GO layers. Because of this intercalation structure of the PCL/GO composite, GO showed a higher reinforcing effect than graphite on the mechanical properties of PCL. The intercalation should have enabled much effective load transfer in the PCL/GO composites. Moreover, GO showed a nucleating effect toward the crystallization of PCL, as the nonisothermal crystallization peak temperature shifted from 258C for pure PCL to about 348C for the PCL/GO composites.

We study photoelectron angular distributions (PADs) near the ionization threshold with a newly developed Coulomb quantum-orbit strong-field approximation (CQSFA) theory. The CQSFA simulations exhibit an excellent agreement with the result from the time-dependent Schrödinger equation. We show that the low-energy fan-shaped pattern in the PADs corresponds to a subcycle time-resolved holographic structure and stems from the significant influence of the Coulomb potential on the phase of the forward-scattered electron trajectories, which affects different momenta and scattering angles unequally. Our work provides a direct explanation of how the fan-shaped structure is formed, based on the quantum interference of direct and forward-scattered orbits. Moreover, our work shows that the fan-shaped pattern can be used to extract information on the target structure, as the number of fringes in the PADs depends strongly on the symmetry of the electronic bound state.