Synthesis, Characterization, and Catalytic Properties of Interlayer Expanded Aluminosilicate IEZ-PLS‑3

An interlayer expanded zeolite IEZ-PLS-3 was postsynthesized from the lamellar precursor of PLS-3 aluminosilicate by interlayer silylation with diethoxydimethylsilane (DEDMS) in HCl–EtOH solution at 443 K for 20 h. The resulting material was characterized by various techniques such as XRD, SEM, adsorption of N₂, water, and benzene, and IR and NMR spectroscopies, and its catalytic properties were investigated by comparison to those of other zeolites with similar Si/Al ratios in <i>m</i>-xylene isomerization/disproportionation, Friedel–Crafts alkylation of anisole with benzyl alcohol, and acylation of anisole with acetic anhydride. The interlayer expansion created new 12 × 10-membered ring (MR) pores in IEZ-PLS-3. IEZ-PLS-3 showed a larger adsorption capacity of benzene than conventional PLS-3 with 10 × 8-MR channels. In the <i>m</i>-xylene isomerization/disproportionation reaction, IEZ-PLS-3 showed a higher conversion than PLS-3 and gave an isomerization to disproportionation ratio close to that of Beta zeolite, characteristic of shape-selective properties of 12-MR zeolites. IEZ-PLS-3 was more active than Beta in Friedel–Crafts alkylation and acylation reactions, implying that it is a promising solid acid catalyst for processing bulky molecules

Improved light extraction efficiency of GaN-based flip-chip light-emitting diodes with

GaN-based flip-chip light-emitting diodes (FC-LEDs) grown on nanopatterned sapphire substrates (NPSS) are fabricated using self-assembled SiO2 nanospheres as masks during inductively coupled plasma etching. By controlling the pattern spacing, epitaxial GaN can be grown from the top or bottom of patterns to obtain two different GaN/substrate interfaces. The optoelectronic characteristics of FC-LED chips with different GaN/sapphire interfaces are studied. The FC-LED with an antireflective interface layer consisting of a NPSS with GaN in the pattern spacings demonstrates better optical properties than the FC-LED with an interface embedded with air voids. Our study indicates that the two types of FC-LEDs grown on NPSS show higher crystal quality and improved electrical and optical characteristics compared with those of FC-LEDs grown on conventional planar sapphire substrates

Wetland-based solutions against extreme flood and severe drought: Efficiency evaluation of risk mitigation

The hydrological regulation services provided by wetlands have great potential to be used as a nature-based solution for improving basin resilience to hydrological extremes. However, the efficiency of wetlands in attenuating hydrological extremes and how this attenuation efficiency varies with the location and type of wetland are not well understood. Here, we used a distributed hydrological modeling platform coupled with isolated and riparian wetland modules (IWs and RWs) to (i) quantify the impacts of wetlands on extreme flood and severe drought and (2) investigate the influences of geographical location and types of wetlands on their regulation efficiency. The hydrological modeling was conducted with various wetland loss scenarios on the Nenjiang River Basin (NRB)- a large river basin where wetlands are abundant and play an important hydrological regulation function. Modeling results showed that RWs mainly decreased peak flow and reduced downstream flood volume. However, IWs predominantly decreased flood volume and slightly mitigated peak flow in the entire NRB. For severe drought, RWs overall alleviated drought while IWs could intensify drought deficit to some extent. In terms of geographical location, upstream wetland obviously amplified downstream flood risks whereas alleviated drought intensity by providing source water for downstream during drought period. Downstream wetland exerted strong hydrological influence on extreme floods and severe droughts and should be restored and conserved preferentially to promote basin hydrologic resilience in the NRB. The methodology in this study can also be applied to other study areas for decision and management when considering spatial distribution and types of wetland restoration for promoting basin hydrologic resilience

Fa xiang wei yi : Peng Kaidong xian sheng juan zeng wen wu te zhan tu lu /

Catalog of long-term exhibition held at Guo li gu gong bo wu yuan, Taibei, Taiwan

High-resistive layers obtained through periodic growth and in situ annealing of InGaN by metalorganic chemical vapor deposition

High-resistive layers were obtained by periodic growth and in situ annealing of InGaN. The effect of the annealing temperature of InGaN on the indium content and the material sheet resistive was investigated. The indium content decreased as the increase of in situ annealing temperature. Additionally, the material sheet resistance increased with the increase of the in situ annealing temperature for the annealed samples and reached 2 × 1010Ω/sq in the light and 2 × 1011Ω/sq in the dark when the in situ annealing temperature reached 970∘C. The acquirement of high-resistive layers is attributed to the generation of indium vacancy-related defects. Introducing indium vacancy-related defects to compensate background carriers can be an effective method to grow high-resistance material

Size-Dependent Catalytic Activity of Oxo-Hydroxo Titanium subnano-islets grafted on Organically Modified Mesoporous Silica

International audienc

Synthesis of Novel Titanosilicate Catalysts by Simultaneous Isomorphous Substitution and Interlayer Expansion of Zeolitic Layered Silicates

A facile and cheap method for the postsynthesis of large-pore titanosilicates from layered zeolitic silicate precursors is presented, in which isomorphous substitution of Ti for Si and interlayer expansion with mobile Si debris are realized simultaneously using aqueous H₂TiF₆ solution at room temperature. This versatile and convenient one-pot postsynthesis was used to construct several different 3D interlayer-expanded zeolite (IEZ) structures with tetrahedrally coordinated Ti incorporated into the framework without the use of external silane. The structural transformation and the incorporation of Ti in the preparation of IEZ-Ti-PLS-3 were monitored using Rietveld refinement and NMR studies. Furthermore, IEZ-Ti-PLS-3 exhibited unique catalytic properties in the epoxidation of alkenes with hydrogen peroxide, and was active not only for linear alkenes but also for bulky cyclic alkenes