Quantum Path Selection and Isolated-Attosecond-Pulse Generation of H2+ with an Intense Laser Pulse and a Static Field

We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum is obviously extended and the short quantum path is selected to contribute to the spectrum, because the corresponding long path is seriously suppressed. Then the combined Coulomb and laser field potentials and the time-dependent electron wave packet distributions are applied to illustrate the physical mechanism of high-order harmonic gen- eration. Finally, by adjusting the intensity of the static field and superposing a properly selected range of the HHG spectrum, a 90-as isolated attosecond pulse is straightforwardly obtained.

Membrane-based air dehumidification:A comparative review on membrane contactors,separative membranes and adsorptive membranes

This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentrated liquid desiccants,separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air,and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification.Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy,this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies.Essentially,the discussion is broken into three sections-one for each category-discriminating in terms of the driving force,membrane structure and properties,and its performance indicators.Readers will notice that despite having the same objective to dehumidify air,the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance.At the end of each section,a performance table or summary of dehumidifying membranes in its class is provided.The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.

Pd catalysts supported on rGO-TiO_2 composites for direct synthesis of H_2O_2: Modification of Pd^(2+)/Pd^0 ratio and hydrophilic property

The use of nanostructured composites as catalyst supports is a promising route to prepare catalysts with high selectivity and productivity. In this work, reduced graphene oxide-TiO_2(rGP-x) composites with a variation of reduced graphene oxide(rGO) content were synthesized by hydrothermal method. Pd/rGP-x catalysts were prepared in incipient-wetness impregnation method for the direct synthesis of H_2O_2 from H2 and O_2. The morphology and electronic properties of catalysts were investigated by XPS, TEM, and Raman spectroscopy.The ratio of Pd^(2+)/Pd^0 and the hydrophobicity of the catalysts were increased with the rising content of rGO. As the amount of rGO in the catalysts varied in the range of 0.025 wt%–2 wt%, the selectivity of H_2O_2 exhibited a tendency of increasing firstly and then decreasing from 0.1 wt% to 2 wt%. It indicates that good catalytic performance for H_2O_2 synthesis can be achieved only when appropriate amount of rGO is introduced. The H_2O_2 selectivity and productivity of Pd/r GP-0.025 both improved remarkably compared with Pd/P25. This enhancement originated from the combined effects of the proper ratio of Pd^(2+)/Pd^0 and hydrophobicity of the catalyst.

Isolation of hemoglobin with metal–organic frameworks Y(BTC)(H_2O)_6

The hierarchical metal-organic frameworks（MOFs）,such as Y（BTC）（H_2O）_6,are prepared with yttrium nitrate and benzene-1,3,5-tricarboxylic acid at room temperature.The product is characterized by Fourier transform infrared（FT-IR）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）and thermogravimetric analysis（TGA）.The Y（BTC）（H_2O）_6 particles are sufficiently rigid for performing solid phase extraction and they exhibit favorable selectivity toward the adsorption of hemoglobin.The adsorption behavior of hemoglobin onto the Y（BTC）（H_2O）_6 fits the Langmuir adsorption model with a theoretical adsorption capacity of 555.6 mg g 1.An adsorption efficiency of 87.7%for 100μg mL 1hemoglobin in 1 mL sample solution（at pH 6.0）is achieved with 0.40 mg Y（BTC）（H20）6.77.3%of the retained hemoglobin is readily recovered using a 0.5%（m/v）SDS solution as the stripping reagent.Circular dichroism spectra indicated that the conformation of hemoglobin is maintained during the adsorption-desorption process.The MOFs material is applied for the isolation of hemoglobin from human blood and the purity of the obtained hemoglobin is further verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis（SDS-PAGE）.