Oxidation of tetralin to 1-tetralone over CrAPO-5

A chromium-incorporated microporous aluminophosphate, CrAPO-5, was tested as a catalyst for the oxidation of tetralin using either a combination of aldehyde and O₂ (1 atm) or tert-butyl hydroperoxide as an oxidant system. The former resulted in significantly improved catalytic performance (69.6% yield to 1-tetralone) over the latter (38.5% yield to 1-tetralone) at 80 °C in 8 h, and conversion increased in the sequence of acetaldehyde?isobutyl aldehyde<pivalaldehyde. CrAPO-5 also exhibited good activity and high selectivity (53.7% yield to 1-tetralone) after 24 h using pivalaldehyde and O₂ at room temperature. Hot filtration and recycle experiments established that oxidation takes place mostly on Cr sites in CrAPO-5. A plausible reaction mechanism involving acylperoxy radicals and oxo-chromium(V) species on CrAPO-5 was proposed for the tetralin oxidation.     

Fatigue Behavior of Thin Sheets of DP590 Dual-Phase Steel

Fatigue properties of 1.6?mm thick dual-phase steel (DP590) sheet have been determined by carrying out axial fatigue tests in load controlled mode at different stress ratios for both smooth specimens and specimens with hole at center. The presence of hole at center of the specimen significantly reduces the fatigue strength. When the fatigue data points are plotted in the Haig-Soderberg diagram, they follow a parabolic relationship for smooth specimens represented by Gerber line and a straight line relationship for the specimens with holes at its center represented by Goodman line. Master Diagram which acts as a guide for the fatigue design is also drawn for both smooth specimens and specimens with holes.     

Large Area Self-Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

Separation membranes with higher molecular weight cut-offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well-defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self-assembly of pre-synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m^-2 h⁻¹ bar⁻¹ is achieved with a complete rejection of brilliant blue-R (BBR; molecular weight = 825 g mol⁻¹) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol⁻¹) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes.