Synthesis and characterization of novel polymeric organic–inorganic complex framework based on sodium 2,4-dioxo-6-aryl-3-oxa-bicyclo[3.1.0]hexane-1,5-dicarboxylate (SDAOBDC) with three-dimensional hybrid networks

Synthesis and characterization of novel polymeric organic–inorganic complex based on sodium 2,4-dioxo-6-aryl-3-oxa-bicyclo[3,1,0]hexane-1,5-dicarboxylate with three-dimensional hybrid networks were reported. The polymeric complex was crystallizing in the triclinic, space group P1. As determined by X-ray single-crystal analysis, in this compound each Na ion is coordinated by six O atoms: two from different carbonyl oxygen atom of carboxylic acid groups, two from bridged carbonyl oxygen atom of carboxylic acid groups, one from the carbonyl oxygen atom of cyclic anhydride and one from water molecule. The structure characterization was done by means of IR, ¹H, ¹³C NMR, UV–Vis spectroscopies, Tg, flame photometry and X-ray crystallographic analysis.     

Influence of flow on longevity of superhydrophobic coatings

Previous studies have demonstrated the capability of superhydrophobic surfaces to produce slip flow and drag reduction, which properties hold considerable promise for a broad range of applications. However, in order to implement such surfaces for practical utilizations, environmental factors such as water movement over the surface must be observed and understood. In this work, experiments were carried out to present a proof-of-concept study on the impact of flow on longevity of polystyrene fibrous coatings. The time-dependent hydrophobicity of a submerged coating in a pressure vessel was determined while exposing the coating to a rudimentary wall-jet flow. Rheological studies were also performed to determine the effect of the flow on drag reduction. The results show that the longevity of the surface deteriorates by increasing the flow rate. The flow appears to enhance the dissolution of air into water, which leads to a loss of drag reduction.     

A manganese oxide with phenol groups as a promising structural model for water oxidizing complex in Photosystem II: a 'golden fish'

We describe here the ability of manganese oxide monosheets to aggregate to form layered structures with 4-aminophenol molecules. These aggregated monosheets could be considered as the first step to synthesize a self-assembled layered hybrid of phenol-manganese ions with phenol and manganese(III) and (IV) as exists in the water oxidizing complex of Photosystem II.     

B-decay signatures of warped top-condensation

We point out that the light radion ?   in a recently proposed Warped Top-Condensation Model (WTCM), can provide distinct signatures in b→s?$b\to s?$, where the on-shell ? can decay with displaced vertices. We find that some of the parameter space of these models is constrained by B-meson and astrophysical data. Future B-decay measurements can lead to the discovery of the WTCM.     

Influence of MgO/CeO2 ratio on CO2-oxidative transformation of C2H6 to C2H4 over highly active and stable Cr/MgO(x)–CeO2(100−x) nanocatalysts

Cr/MgO(x)–CeO₂(100?x) nanocatalysts were synthesized by a coprecipitation method and characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray (EDX) spectroscopy, diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) analysis. The effect of ceria addition on their physicochemical characteristics was investigated, and the results were correlated with their catalytic performance in oxidative dehydrogenation of ethane. A decrease in the size of the metal particles was found when adding a suitable content of ceria to the support. Crystalline Cr₂O₃ was not found in the calcined samples, indicating good dispersion of Cr species on the support. All samples showed nanosized particles with uniform morphology, with the best surface morphology for the Cr/MgO(50)–CeO₂(50) sample, on which the particle distribution mainly lay in the range of 40–60 nm. Variation of the amount of Ce in the support led to an enhancement of the Cr⁶⁺/Cr³⁺ ratio, with the highest value for the Cr/MgO(50)–CeO₂(50) sample. This catalyst effectively dehydrogenated ethane to ethylene with CO₂ at 700 °C even after 5 h on-stream, giving 42.76 % ethylene yield.

     

Catalytic wet air oxidation of phenol over ultrasound-assisted synthesized Ni/CeO2–ZrO2 nanocatalyst used in wastewater treatment

Non-noble metal Ni with different loadings was coated on precipitated CeO₂–ZrO₂ support by the sonochemistry method and examined for catalytic wet air oxidation of phenol. The structure of the nanocatalysts was determined by BET, FESEM, XRD, and FTIR analyses. The results showed non-uniform morphology of the nanocatalyst at lower Ni contents changed to homogenous morphology with spherical nano particles at higher Ni contents. While the size of NiO crystals remained constant with rising Ni content, the crystallinity of NiO significantly increased. If the crystallinity of NiO was 100% in 20% wt Ni/CeO₂–ZrO₂, the crystallinity of NiO in 5% wt Ni was found to be 41.13%. The average particle size in Ni(15%)/CeO₂–ZrO₂ was 77 nm in which 85.71% of particle diameters were less than 100 nm. Catalytic wet air oxidation of phenol with different Ni loadings indicated improvement of phenol destruction at higher amounts of active phase. Removal of phenol increased with increasing catalyst loading from 4 to 9.0 g/l but further increase to 10 g/l declined the catalyst reactivity.     

Lattice Boltzmann Pore Scale Simulation of Natural Convection in a Differentially Heated Enclosure Filled with a Detached or Attached Bidisperse Porous Medium

In this research, pore scale simulation of natural convection in a differentially heated enclosure filled with a conducting bidisperse porous medium is investigated using the thermal lattice Boltzmann method. For the first time, the effect of connection of the bidisperse porous medium to the enclosure walls is studied by considering the attached geometry in addition to the detached one. Effect of most relevant parameters on the streamlines and isotherms as well as hot wall average Nusselt number is studied for two of the bidisperse porous medium configurations. It is observed that effect of geometrical and thermo-physical parameters of the bidisperse porous medium on the heat transfer characteristics is more complicated for the attached configuration. To assess the validity of the local thermal equilibrium condition in the micro-porous media, the pore scale results are used to compute the percentage of the local thermal non-equilibrium for two of the bidisperse porous medium configurations. It is concluded that for the detached configuration, the local thermal equilibrium condition is confirmed in the entire micro-porous media for the ranges of the parameters studied here. However, for the attached geometry, it is shown that departure from the local thermal equilibrium condition is observed for the higher values of the Rayleigh number, micro-porous porosity, solid–fluid thermal conductivity ratio, and the smaller values of the macro-pores volume fraction.     

Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium

Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Peclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on the Br 〈 0 case where there is somewhere that heat transfer changes direction at some streamwise location to the wall instead of its original direction, i.e., from the wall.     

Preparation of novel,liquid, solvent‐free,polyolefin‐based adhesives

An innovative procedure for functionalization of polyolefins was developed. It was found that synthesized polyolefins end‐capped with trimethoxysilane (silylated polyolefins) are new polyolefin‐based adhesives. To prepare the mentioned materials,1‐octene as a higher α‐olefin was cooligomerized with two linear, nonconjugated dienes (ie, 1,5‐hexadiene and 1,7‐octadiene) by using metallocene catalyst system, Cp₂HfCl₂/MAO, at room temperature. Then, amine‐terminated trimethoxysilane (3‐aminopropyltrimethoxysilane) was reacted with unsaturated bonds of synthesized cooligomers in the presence of palladium(II) acetate. Embedding of the dienes on 1‐octene oligomeric chains was explored by Fourier transform infrared (FTIR), ¹H, and ¹³C‐NMR spectroscopy. On the basis of the results, 1,5‐hexadiene showed both 1‐butene branch and five‐member ring. On the other hand, 1,7‐octadiene was incorporated by 1,2‐addition, forming both 1‐hexene branch and seven‐member ring in the cooligomer backbone. Mole percentage of C?C and cyclic moieties reached to a value of 28.54, 18.59% mol in 1‐octene/1,5‐hexadiene, and 38.04, 6.71% mol in 1‐octene/1,7‐octadiene cooligomers, respectively. Reaction of synthesized cooligomers with 3‐aminopropyltrimethoxysilane was confirmed by FTIR spectroscopy, which yielded targeted adhesives. To study the adhesion properties, resulting adhesives were applied to different substrates. Obtained results demonstrated that tensile shear strength of synthesized adhesives to polar substrates was 2.21% to 2.84% more than nonpolar substrates. Among studied systems, the best performance was achieved by1‐octene/1,7‐octadiene–based adhesive and Al substrate with tensile shear strength of 1.45 N/mm².     

Efficient Method for Tetrahydropyranylation of Alcohols and Phenols and Deprotection of THP Ethers using H14[NaP5W30O110] as a Green Catalyst

A simple and effective method for tetrahydropyranylation of alcohols and phenols and the regeneration of THP ethers using a catalytic amount of H₁₄[NaP₅W₃₀O₁₁₀] is reported.