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0402867_Lacks

Molecular Simulation of Disordered Materials under Stress Daniel J. Lacks, Case Western Reserve University, DMR 0402867.

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0402867_Lacks

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  1. Molecular Simulation of Disordered Materials under Stress Daniel J. Lacks, Case Western Reserve University, DMR 0402867 Lightweight materials can be used to help reduce our energy consumption. One route to make lightweight materials is to introduce porosity. In nature, evolution led to porous bone in order to reduce the weight of the skeleton and thus minimize the energy required for movement. However, the introduction of porosity is not without cost, as porosity compromises the mechanical properties of the material. Together with collaborators, we have shown that nature’s attempts to maximize the mechanical performance for a given density can be topped with nanotechnology. In particular, nanoporous silicas prepared by surfactant-directed self-assembly show mechanical properties that are much less sensitive to porosity than natural solids. This behavior occurs because the nanoscale structure induces changes in the atomic level, as demonstrated by Raman and NMR experiments and molecular simulations. The modified atomic level structure, which is denser and is characterized by smaller silica rings (see Figure on right), is significantly stiffer than the ordinary (bulk) silica structure. H. Fan, C. Hartshorn, T. Buchheit, D. Tallant, R. Assink, R. Simpson, D. J. Lacks, S. Torquato and C. J. Brinker, “Modulus/density scaling behavior and framework architecture of nanoporous, self-assembled silicas”, Nature Materials6, 418 (2007).

  2. Molecular Simulation of Disordered Materials under Stress, Daniel J. Lacks, Case Western Reserve University, DMR 0402867 An emphasis of this project is a strong effort to mentor undergraduate student researchers. Over the 11 years of NSF support, thirteen undergraduate researchers have been co-authors on papers in peer-reviewed journals. Two of these undergraduate researchers are African-American, and five are women. Kelly Cummins (B.S., 2001) -Lei, Cummins, Lacks, “First-principles enthalpy landscape analysis of structural recovery in glasses”, J. Polym. Sci. B: Polym. Phys. 41, 2302 (2003) Nathan Duff (B.S., 2007) -Duff, Wang, Mann, Lacks, “Molecular Dynamics Investigation of Bent-Core Molecules on a Water Surface”, Langmuir 22, 9082 (2006). -Duff, Duong, Lacks, “Stretching the Immunoglobulin 27 domain of the titin protein: The dynamic energy landscape”, Biophys. J. 91, 3446 (2006) -Duff, Lacks, Shear-induced crystallization in jammed systems”, Phys. Rev. E 75, 031501 (2007) -Duff, Lacks, “Particle Dynamics Simulations of Triboelectric Charging in Granular Insulator Systems”, J. Electrostatics, in press Brittany Isner (B.S., 2007) -Isner, Lacks, “Generic rugged landscapes under strain and the possibility of rejuvenation in glasses”, Phys. Rev. Lett. 96, 025506 (2006) Gerard Gagnon (B.S., 2001) -Gagnon, Patton, Lacks, “Energy landscape view of fracture and avalanches in disordered materials”, Phys. Rev. E. 64, 051508 (2001) Kaye Grant (B.S., 1998) -Roberts, Wienhoff, Grant, Lacks , "Structural transformations in silica glass under high pressure", J. Non-Cryst. Solids 281, 205 (2001) Matthew Kottemann (B.S., 2001) -Lacks, Kottemann, Yuan, “First- and second-order diatomic-to-monatomic phase transitions in a model crystal”, Chem. Phys. Lett. 347, 178 (2001) Yuning Lei (B.S., 2004) -Lei, Cummins, Lacks, “First-principles enthalpy landscape analysis of structural recovery in glasses”, J. Polym. Sci. B: Polym. Phys. 41, 2302 (2003) Djordje Nikolic (B.S., 2001) -Nikolic, Lacks, “Size scaling of mutation avalanches in a model for protein evolution”, J. Theoretical Biology 221, 259 (2003) Quyen Nguyen (B.S., 1999) -Nguyen, McGann, Lacks, "Elastic stability limits of polyethylene and n-alkane crystals from molecular simulation", J. Phys. Chem.B 103, 10679 (1999) Jaqunda Patton (B.S., 2000) -Gagnon, Patton, Lacks, “Energy landscape view of fracture and avalanches in disordered materials”, Phys. Rev. E. 64, 051508 (2001). Christopher Rives (B.S., 2002) -Rives, Lacks, “Avalanches and self-organized criticality in simulations of particle piles”, Chem. Phys. Lett. 370, 700 (2003) Madeleine Roberts (B.S., 2000) -Roberts, Wienhoff, Grant, Lacks , "Structural transformations in silica glass under high pressure", J. Non-Cryst. Solids 281, 205 (2001) Jeff Wienhoff (B.S., 1999) -Roberts, Wienhoff, Grant, Lacks , "Structural transformations in silica glass under high pressure", J. Non-Cryst. Solids 281, 205 (2001) -Lacks, Wienhoff, "Disappearances of Energy Minima and Loss of Order in Polydisperse Colloidal Systems ", J. Chem. Phys. 111, 398 (1999)

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