Department of Chemical Engineering
City College of New York
B.S. (Ch.E. and Math.), 1978,
Cooper Union;
M.S.(Ch.E.), 1979,
Ph.D.(Ch.E.), 1984,
University of California at
Berkeley, NSF Presidential Young Investigator
Reaction engineering; transport and reaction aspects of artery disease; hydrodynamics of two phase flow in tubes
A chemical engineer's perspective, considering chemical and biological changes as kinetic reactions and focusing on transport, can often offer a fresh approach to problems in biology. Our group has been studying the initiation of arterial disease. We have developed kinetic models from the extensive historic data of Brown and Goldstein for the processes by which many human cells take up and process blood-borne cholesterol and for how they maintain cholesterol homeostasis. In addition, together with Professor Shu Chien (University of California, San Diego ) and S. Weinbaum, we have been developing very successful models to decipher the earliest stages of arterial (intimal) cholesterol lesion formation. These models, in conjunction with animal experiments at UCSD, explain the transendothelial transport of lipoprotein cholesterol and subsequent spread within the artery wall. Current work is linking this transport to the kinetics of formation and growth of subendothelial extracellular lipid liposomes and to the cellular processes discussed above for dissipating them. The aim is to show how these steps comprise the earliest steps and how they can lead to lesion formation.
Another area that our group has focused on is the stability, both linear and nonlinear, of two-phase core-annular flows. The geometric distribution of two fluids in a conduit or pore is crucial to problems as diverse as recovering oil from rock pores to low cost pipe-transport of heavy crudes to the plugging of alveoli that hampers breathing in premature babies. In the absence of flow, we have shown that if one fluid is electrolytic, double layers at the wall and at the fluid-fluidinterfacecan stabilize the capillary instability. For situations with flow, we have developed methods for asymptotically thin films that clearly separate out the physical effect that compete to determine the interface's stability. Combination with Bretherton's theory gives a stability relation for liquid-liquid displacements. Asymptotic nonlinear results show how a base flow can interact both linearly and nonlinearly to stabilize other linearly destabilizing mechanisms and can mitigrate the tendency in the absence of a second fluid for the interface to lapse into chaotic motions. Current boundary-integral calculations hope to follow growing instabilities to break up. In addition we are investigating the effects of pore corrugation and other nonidealities.
Finally, recent work with Dr. Lee Walters at the Scripps Research Institute is aimed at developing new experimental techniques for increasing the time-resolution of FTIR spectroscopy by at least an order of magnitude to the sub-millisecond regime. The goal is to observe early time intermediates in protein refolding.
Harris Wong
B.E. (M.E.), 1985, McGill University; Ph.D.(M.E.),1992, University of California, Berkeley
Fung, S.C., Querini, C.A., Liu, K., Rumschitzki, D.S. and Ho, T.C., "In situ coking kinetics obtained from a new flow through microbalance and reaction kinetics monitored by GC," Studies in Surf.Sci. Catal.: Catalyst Deactivation, 88, 305 (1994).
Huang, Y., Rumschitzki, D., Chien, S. and Weinbaum, S., "A fiber matrix model for the growth of macromolecular leakage spots in the arterial intima," ASME J. of Biomechanical Eng., 116(4), 430, 1994.
Rumschitzki, D.S. and Liu, K., "Zwietering's maximum-mixedness reactor and the continuously stirred tank reactor," Chemical Engineering Science, 49(23), 3883, 1994.
Wong, H., Rumschitzki, D. and Maldarelli, C., "On the surface mass balance at a deforming interface," Physics of Fluids, 8(11), 3203 (1996).
Chauhan, A., Maldarelli, C., Rumschitzki, D. and Papageorgiou, D., "The temporal and spatial instability of an inviscid compound jet," Rheologica Acta, 35, 567 (1996).
Huang, Y., Rumschitzki, D., Chien, S. and Weinbaum, S., "A fiber matrix model for the filtration through fenestral pores in a compressible arterial wall," Amer. J. Physiol., 272 (41), H2023 (1997).
Yin, Yongyi, Lim, K.-H., Weinbaum, S., Chien, S.and Rumschitzki, D.S.,
"A
model for the initiation and growth of extracellular lipid liposomes in arterial intima,"
Amer. J. Physiol.,
272(41), H1033 (1997).
Liu, K., Fung, S.C., Ho, T.C. and Rumschitzki, D.S., "Identification of coke precursors in n-heptane reforming with a multi-outlet fixed bed reactor and a novel vibrational microbalance," Journal of Catalysis, 169, 455 (1997).
Liu, K., Fung, S.C., Ho, T.C. and Rumschitzki, D.S., "Kinetics of catalyst coking in n-heptane reforming over Pt-Re/Al 2O3," Indust. & Eng. Chem. Res., 36(8), 3264 (1997).
Liu, K., Fung, S.C., Ho, T.C. and Rumschitzki, D.S., "An experimental protocol for studying kinetics and catalyst deactivation: Application to heptane reforming," Studies in surface science and catalysis: Catalyst Deactivation , 111, 625 (1997).
Wong, H., Rumschitzki, D. and Maldarelli, C., "Theory and experiment on the low Reynolds number expansion, contraction and detachment of a bubble pinned at the tip of a submerged capillary," Journal of Fluid Mechanics, 356, 93 (1998).
Huang, Y., Jan, K.M., Rumschitzki, D. and Weinbaum, S., "Structural changes in rat aortic intima due to transmural pressure," ASME J. Biomech. Eng., 120, 476 (1998).
Wong, H., Rumschitzki, D. and Maldarelli, C., "Marangoni effects on the motion of an expanding or contracting bubble pinned at a submerged tube tip," Journal of Fluid Mechanics, 379, 279 (1998).
Chauhan, A. Maldarelli, C., Papageorgiou, D. and Rumschitzki, D., "The temporal instability of a compound thread,": Journal of Fluid Mechanics, in press (1999)
Wei, H. H. and Rumschitzki, D., "The linear stability of a core annular flow in a corrugated tube," IUTAM Symposium on nonlinear wave behavior in multi-phase flows, Kluwer, in press (2000)
Chauhan, A., Rumschitzki, D., Maldarelli, C. and Papageorgiou, D., "The spatial instability of a viscous, compound, two-phase jet," submitted for the Journal of Fluid Mechanics (1998).