Centers and Institutes   |
My current research focuses on study of laser-induced heating, melting and evaporation to remove damaged material, heal subsurface cracks, smooth the surface, and anneal residual stress in the affected region of an optic. Most of the experimental work involves thermal radiation measurements and diagnostics of laser heated optical materials to derive spatial and temporal temperature profiles. The temperature measurements are then used to validate thermal diffusion models and thus develop a predictive, physics-based computational capability to accurately simulate energy deposition/transport and material hydrodynamics in fused silica under conditions relevant to stress annealing and optical damage mitigation with infrared lasers.
Additionally, I study the dynamic surface processes of spores and bacteria membrane under different types of environmental perturbations. Atomic force microscopy is used to achieve sub-nanometer resolution of surface morphology, overgrowth, and membrane components assembly in-situ (liquid). Using similar techniques for imaging and sample preparation, I study crystal growth by organic growth-modifiers to provide insights into the fundamental role of water entropy in regulating growth kinetics. Results of AFM studies in solvent containing atmosphere were used to develop new, probe-based, mitigation approach of non-linear optics damage.
Elhadj S., Chernov, A.A., and De Yoreo, J.J. (2008) Solvent-mediated repair and patterning of surfaces by AFM, Nanotechnology, 105304.Chung, S.-W., Presley, A.D., Elhadj S., Hok, S., Hah, S.-S., Chernov, A.A., Francis, M.B., Eaton, B.E., Feldheim, D.L., and De Yoreo, J.J. (2008). Scanning probe-based fabrication of 3D nanostructures via affinity templates, functional RNA and meniscus-mediated surface remodeling”, Scanning, 30(2), 159-171.
Elhadj, S., Han,N., De Yoreo, J.J., and Dove, P.M. (2006). Role of molecular charge and hydrophilicity in regulating the kinetics of crystal growth, PNAS, 103(51), 19237-19242.
Elhadj, S., Salter, A., Wierzbicki, A., De Yoreo, J.J., Han, N., and Dove P.M., (2006) "Peptide Controls on Calcite Mineralization: Polyaspartate Chain Length Affects Growth Kinetics and Acts as a Stereochemical Switch on Morphology", Crystal Growth and Design, 6(1), 197-201.
Elhadj, S., Salter, A., Dove P.M., Wierzbicki, A., and De Yoreo, J.J. (2005). Polyaspartate as a stereochemical switch for controlling the growth and morphology of calcite. Geochimica et Cosmochimica Acta, 69, 120.
Elhadj, S., Singh, G., and Saraf, R.F. (2004). Optical Properties of Immobilized DNA from 255 to 700 nm, Langmuir, 20(13), 5539-5543.
Elhadj, S., Chan, R., and Forsten-Williams, K. (2004). Implementation of an optical method for the real-time determination of uniaxial strain and vessel mechanics, IEEE Transactions Biomedical Engineering, 51(3):536-538.
Elhadj, S., Woody, J.W., Niu, V.S., and Saraf, R.F. (2003). Orientation of Self-assembled Block Copolymer Cylinders Perpendicular to Electric Field in Mesoscale Film", Applied Physics Letters, 82(6):871-873.
Elhadj, S., Akers, R.M., and Forsten-Williams, K. (2003). Chronic Pulsatile Shear Stress Alters Insulin Like Growth Factor-I (IGF-I) Binding Protein Release in vitro. Annals of Biomed Engineering, 31(2):163-170.
Elhadj, S., Mousa, S.A., and Forsten-Williams K. (2002). Chronic pulsatile shear stress impacts synthesis of proteoglycans by endothelial cells: effect on platelet aggregation and coagulation. Journal of Cellular Biochemistry, 86(2):239-250.
Loui A, Elhadj S. Sirbuly S, McCall S, and Ratto T, Heat Conduction Effects on the Performance of Piezoresistive Cantilever Array Sensors, (in prep).