Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Catalysis. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

Dissociation Constants (pKa) of Tertiary and Cyclic Amines: Structural and Temperature Dependences

Abstract: The dissociation constants of the conjugate acids of 14 amines (diethylethanolamine, monoethanolamine, n-butyldiethanolamine, t-butyldiethanolamine, n,n-dimethylpropanolamine, methyl-diethanolamine, ethyldiethanolamine, monoethylethanolamine, n,n-dimethylisopropanolamine, triethanolamine, 4-methylpiperazine-1-amine, 3-morpholino propylamine, 4,2-hydroxylethylmorpholine, and triethylamine) were measured over a temperature range between 293.15 and 333.15 K using the potentiometric titration method. The change in standard state thermodynamic properties was derived from the van’t Hoff equation. The influence of the steric hindrance, number of −OH groups, and length of alkyl chain on the dissociation constants was identified. Of the studied amines, few sterically hindered derivatives of piperazine, a secondary amine monoethylethanolamine, and a tertiary amine n,n-dimethylpropanolamine have high pKa values but lower standard enthalpy than those of the benchmark amine, monoethanolamine (MEA), and thus were deeme...

Molecular Simulations of Hydrogen Storage in Carbon Nanotube Arrays

Abstract: Grand canonical ensemble Monte Carlo (GCEMC) molecular simulations of hydrogen storage at 298 and 77 K in triangular arrays of single wall carbon nanotubes (SWCNT) and in slit pores (modeling activated carbons) were performed. At 298 K the US DOE target gravimetric hydrogen storage capacity (6.5 wt %) is reached at 160 bar for optimally configured arrays of open SWCNT of wide diameter, but the equivalent volumetric capacity is ∼40% of the DOE target [695 (STP) v/v]. For slit pores at 298 K the optimal volumetric capacity is ∼20% of the target. Simulations for 77 K and 70 bar indicate that triangular arrays of open and closed SWCNT of various diameters in a wide range of configurations exceed the DOE gravimetric target. A capacity of 33 wt % is found for arrays of narrow, open, or closed SWCNT that are widely spaced. Here, adsorption occurs entirely in the interstitial space between the nanotubes. Volumetric capacities close to the DOE target are found for arrays of narrow, open or closed SWCNT with a rang...

Dispersoid strengthening of a high temperature Al–Si–Cu–Mg alloy via Mo addition

Abstract: The influence of Mo addition on the microstructure and mechanical properties of an Al–7Si–05Cu–03Mg alloy (wt%) was investigated The Mo-containing alloy exhibited significant improvement in creep resistance over the base alloy At 300 °C and 30 MPa, the minimum creep rate decreased by 95% while creep time-to-fracture was increased by 2 orders of magnitude, from 50 min to 1500 min The tensile yield strength at 300 °C was also increased by 25% These effects were attributed to the formation of novel Al–(Fe,Mo)–Si dispersoids during solution treatment in the grain interiors (intradendritic regions) Unlike the age-hardening precipitates, which coarsened resulting in loss of strength, these dispersoids were thermally stable and retained their strengthening effect at 300 °C TEM investigations showed that the dislocation motions were effectively hindered by these fine dispersoids, leading to the reduction in the minimum creep rate The onset of the tertiary creep stage was delayed by postponing the dislocation pile-up at the interdendritic Si particles It was found that Mo addition suppressed the formation of the brittle plate-like β-Al5FeSi intermetallics and formed a blocky phase in the cast microstructure, which resulted in 34% increase in elongation at 300 °C