Deacetoxy/deacetylcephalosporin C synthase (acDAOC/DACS) from Acremonium chrysogenum is a bifunctional enzyme that catalyzes both the ring-expansion of penicillin N to deacetoxycephalosporin C (DAOC) and the hydroxylation of the latter to deacetylcephalosporin C (DAC). Three residues N305, R307 and R308 located in close proximity to the C-terminus of acDAOC/DACS were each mutated to leucine. Th...

Immobilized enzymes generate net fluid flow when exposed to specific reagents in solution. Thus, they function as self-powered platforms that combine sensing and on-demand fluid pumping. To uncover the mechanism of pumping, we examine the effects of solutal and thermal buoyancy on the behavior of phosphatase-based micropumps, using a series of reactants with known thermodynamic and kinetic para...

In recent years the usefulness of enzymatic systems to obtain a single stereoisomerically pure compound starting from a racemate has been expanded. Moreover, current advances in protein engineering, molecular biology and modeling tools are the basis to improve the catalytic properties of enzymes to face novel synthetic challenges. Also, medium engineering and novel immobilization methods of (bi...

The objective of this project was to develop and apply fundamentally based experimental andcomputational methodologies that can lead to the design of improved supercritical fuel/catalyst/heatexchanger systems for cooling hypersonic vehicles. This project was a multi-team effort involvingresearchers at the University of Delaware, United Technologies Research Center, and the Colorado<...

We investigate the catalytic reactions model used in cell modeling. The reaction kinetic is defined through the energies of different species of molecules following random independent distribution. The related statistical physics model has three phases and these three phases emerged in the dynamics: fast dynamics phase, slow dynamic phase and ultra-slow dynamic phase. The phenomenon we found is...

Design of highly efficient multifunctional reaction processes for energy production is one of the main focus areas of Chemical Engineering. This article presents multiscale simulation frameworks for heterogeneously catalyzed reactors wherein numerous synthesis steps are integrated for high efficiency biodiesel production. The goal is the modeling of transport-adsorption-reactiondesorption pheno...

To address the problem of acute cocaine overdose, we undertook molecular engineering of butyrylcholinesterase (BChE) as a cocaine hydrolase so that modest doses could be used to accelerate metabolic clearance of this drug. Molecular modeling of BChE complexed with cocaine suggested that the inefficient hydrolysis (k(cat) = 4 min(-1)) involves a rotation toward the catalytic triad, hindered by T...

Catalytic dehydrogenation of ammonia-borane (NH(3)·BH(3), AB) and dimethylamine borane (NHMe(2)·BH(3), DMAB) by the Pd(II) complex [((tBu)PCP)Pd(H(2)O)]PF(6) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] leads to oligomerization and formation of spent fuels of general formula cyclo-[BH(2)-NR(2)](n) (n = 2,3; R = H, Me) as reaction byproducts, while one equivalent of H(2) is released per amine-bo...

Interfacial enzymes present additional challenges in their study compared to enzymes with soluble substrates. Cholesterol oxidase is an interfacial enzyme that transiently associates with lipid membranes to convert cholesterol to cholest-4-en-3-one. As a case study to exemplify the issues that should be considered, we describe our structural and mechanistic understanding of cholesterol oxidase ...

The present paper is primarily concerned with modeling complex turbulent wall-bounded flow in spray-painting processes by using a commercial CFD code. Computational results of turbulent channel flow with low Reynolds numbers are compared with DNS data in order to obtain the performance of turbulence models and near wall treatments. The realizable k-ε model with the nonequilibrium wall function ...