Videos & Animations
Enjoy these Videos and Animations from the Molecular Design Institute and the Ward Group!
ACTIVE MATTER
Micron-scale metal rods with uniform Au-Pt segments swim by self-electrophoresis when placed in a solution of hydrogen peroxide fuel. Electrochemical decomposition of hydrogen peroxide at the opposite ends of the rod produces a gradient in proton concentration, which corresponds to an electric field pointing from Pt to Au. The rods themselves have an overall negative charge, so the positively charged electrical double layer surrounding the rod experiences a force due to the self-generated electrical field. A fluid flow develops on the rod surface, from Pt to Au, causing the rod to swim with its Pt end leading.
Swimmers are hydrodynamically attracted to teardrop-shaped posts creating by lithography, swimming alongside the post perimeter for long times before leaving. The rods experience a higher rate of departure from the higher curvature end of the teardrop shape, thereby introducing a bias into their motion that can be translated to macroscopic directional motion over long times by using arrays of teardrop-shaped posts aligned along a single direction. This method promises a protocol for concentrating swimmers and transporting cargo to desired locations. [M. S. Davies Wykes, X. Zhong,b J. Tong, T. Adachi, Y. Liu, L. Ristroph, M. D. Ward, M. J. Shelley, J. Zhang, Soft Matter, 2017, 13, 4669-4800]
Micron-scale metal rods with uniform Au-Pt-Au segments create extensile flows in the presence of hydrogen peroxide fuel, forming rotors when aggregated through dynamic self-assembly, which is driven by both hydrodynamic and electro-kinetic interactions. The direction of the rotation is a consequence of offset between the rods and the extensile outer flow fields. Here the rotors find a friend. [M. S. Davies Wykes, J. Palacci, T. Adachi, L. Ristroph, X. Zhong, M. D. Ward, J. Zhang, M. Shelley, Soft Matter, 2016,12, 4584-458
Micron-scale metal rods with uniform Au-Pt-Au segments create extensile flows in the presence of hydrogen peroxide fuel, forming rotors when aggregated through dynamic self-assembly, which is driven by both hydrodynamic and electro-kinetic interactions. The direction of the rotation is a consequence of offset between the rods and the extensile outer flow fields. Here, a rotor spins in one direction, then forms a "T" swimmer on the way to forming a rotor with the opposite chirality (in 2D).[M. S. Davies Wykes, J. Palacci, T. Adachi, L. Ristroph, X. Zhong, M. D. Ward, J. Zhang, M. Shelley, Soft Matter, 2016,12, 4584-458]
Micron-scale metal rods with uniform Au-Pt-Au segments create extensile flows in the presence of hydrogen peroxide fuel, forming rotors when aggregated through dynamic self-assembly, which is driven by both hydrodynamic and electro-kinetic interactions, but also forming T-swimmers that swim as a results of extensile flow patterns. The reversible transition between these two configurations is reminiscent of bacterial run-and-tumble motion. [M. S. Davies Wykes, J. Palacci, T. Adachi, L. Ristroph, X. Zhong, M. D. Ward, J. Zhang, M. Shelley, Soft Matter, 2016,12, 4584-458]
CRYSTAL GROWTH
Real-time in situ Atomic Force Microscopy video of L-cystine growth, which is actuated by a screw dislocation that continuously generates spirals from the dislocation core. The hexagonal shape of the spiral hillocks reflects the hexagonal crystallographic symmetry.
Real-time in situ Atomic Force Microscopy video of L-cystine growth, which is actuated by a single screw dislocation that continuously generates spirals from the dislocation core. The hexagonal shape of the spiral hillocks reflects the hexagonal crystallographic symmetry. [ A. G. Shtukenberg, Z. Zhu, Z. An, M. Bhandari, P. Song, B. Kahr, M. D. Ward, Proc. Natl. Acad. Sci. 2013, 110, 17195-17198; L. N. Poloni, Z. Zhu, N. Garcia-Vázquez, A. Yu, D. Connors, L. Hu, A. Sahota, M. D. Ward, and A. G. Shtukenberg, Cryst. Growth Des. 2017, 17, 2767−2781]
Simulation of the spiral growth from a single L-cystine dislocation core, using actual data acquired by real-time in situ AFM. The simulation illustrates the phenomena of "bunching", which results from the attachment kinetics anisotropy of the six-sided molecular layers. The slowest step hinders the advancement of the steps above, creating six bunched steps with heights equal to the unit cell along the dislocation direction. [ A. G. Shtukenberg, Z. Zhu, Z. An, M. Bhandari, P. Song, B. Kahr, M. D. Ward, Proc. Natl. Acad. Sci. 2013, 110, 17195-17198
Real-time AFM of L-cystine growth, which is actuated by two proximal heterochiral dislocations, also known as a Frank-Read source, which continuously generate spirals from the dislocation cores. The spirals merge to form closed loop islands, creating the illusion of a spiral, which is a consequence of six-sided irregular, but congruent, polygonal molecular layers stacking on top of each other as they form. [ A. G. Shtukenberg, Z. Zhu, Z. An, M. Bhandari, P. Song, B. Kahr, M. D. Ward, Proc. Natl. Acad. Sci. 2013, 110, 17195-17198]
Simulation of L-cystine growth, which is actuated by two proximal heterochiral dislocations, also known as a Frank-Read source, which continuously generate spirals from the dislocation cores. The spirals merge to form closed loop islands, creating the illusion of a spiral, which is a consequence of six-sided irregular, but congruent, polygonal molecular layers stacking on top of each other as they form. [ A. G. Shtukenberg, Z. Zhu, Z. An, M. Bhandari, P. Song, B. Kahr, M. D. Ward, Proc. Natl. Acad. Sci. 2013, 110, 17195-17198]
CRYSTAL GROWTH INHIBITION
A single dislocation on the surface of a crystal of the PX23 receptor antagonist (Afferent Pharmaceuticals). The micromorphology reflects the symmetry of the (011) crystal surface as deduced from the crystal structure. [L. N. Poloni, A. P. Ford, M. D. Ward, Cryst. Growth. Des. 2016, 16, 5525 – 5541]
A single dislocation on the surface of a crystal of the PX23 receptor antagonist (Afferent Pharmaceuticals) with an inhibitor added to the growth solution. The inhibitor, a mimic of the solute, binds non-uniformly to the steps on the dissymmetric spiral, resulting in an anisotropic growth of the spiral. [L. N. Poloni, A. P. Ford, M. D. Ward, Cryst. Growth. Des. 2016, 16, 5525 – 5541]
Two proximal dislocations on the surface of a crystal of the PX23 receptor antagonist (Afferent Pharmaceuticals) with opposite chiralities collide. [L. N. Poloni, A. P. Ford, M. D. Ward, Cryst. Growth. Des. 2016, 16, 5525 – 5541]
DISLOCATION GENERATION BY PARTICLES
AFM video of growth on a {0001} L-cystine face above the inclined hematite particle after the particle was overgrown. Four screw dislocations were generated. Image size = 0.67 x 0.67
microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
AFM video of growth on a {0001} L-cystine face above the inclined hematite particle after the particle was overgrown. Four screw dislocations were generated. Image size = 2 x 2 microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
AFM video of growth on a {0001} L-cystine face above the inclined hematite particle after the particle was overgrown. Four screw dislocations were generated. Image size = 1 x 1 microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
AFM video of the initial stages of dissolution after growth over an inclined hematite particle that generated two pairs of heterochiral dislocations. Image size = 2 x 2 microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
AFM video of the intermediate stage of dissolution after growth over an inclined hematite particle that generated two pairs of heterochiral dislocations. Four etch pits were observed above the submerged hematite particle. Image size = 1 x 1 microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
AFM video of the final stage of dissolution after growth over an inclined hematite particle. Etch pits were absent after detachment of the hematite particle during dissolution, revealed a dislocation-free basal plane on the (0001) surface L-cystine. Image size = 0.67 x 0.67
microns. [X. Zhong, A. G. Shtukenberg, T. Hueckel, B. Kahr, M. D. Ward, Cryst. Growth Des. 2018, 18, 318–323]
ICE DYNAMICS
Image of a D2O crystal in contact with liquid H2O confined within a microfluidic device. At a constant temperature, the interface between the solid crystal and liquid exhibits a scalloped morphology with convex and concave sections that cycled between growth and retreat. This behavior is a consequence of H/D exchange across the solid–liquid interface, latent heat exchange, local thermal gradients, and the Gibbs–Thomson effect on the melting points of the convex and concave features. [R. Drori, M. Holmes-Cerfon, B. Kahr, R. V Kohn, M. D. Ward, Proc. Natl. Acad. Sci. USA 2017, 114, 11627–11632
Image of a D2O crystal in contact with liquid H2O confined within a microfluidic device. At a constant temperature, the interface between the solid crystal and liquid exhibits a scalloped morphology with convex and concave sections that cycled between growth and retreat. This behavior is a consequence of H/D exchange across the solid–liquid interface, latent heat exchange, local thermal gradients, and the Gibbs–Thomson effect on the melting points of the convex and concave features. [R. Drori, M. Holmes-Cerfon, B. Kahr, R. V Kohn, M. D. Ward, Proc. Natl. Acad. Sci. USA 2017, 114, 11627–11632]
CRYSTALLIZATION AND POLYMORPHISM OF INSECTICIDES
Spherulites of DDT Form I growing on a glass surface. [J. Yang, C. Hu, X. Zhu, Q. Zhu, M. D. Ward, B. Kahr, Angew. Chem. 2017, 129,10299 –10303
Concomitant polymorphs of DDT Forms I and II growing on a glass surface. [J. Yang, C. Hu, X. Zhu, Q. Zhu, M. D. Ward, B. Kahr, Angew. Chem. 2017, 129,10299 –10303]
Fruit flies (Drosophilia Melangaster) exposed to DDT Forms I and II, and comparison to a control (no DDT). The flies exposed to Form II exhibit hyperactivity and cease to move earlier than Form I. The control flies live far beyond the flies in either Form I or II. [J. Yang, C. Hu, X. Zhu, Q. Zhu, M. D. Ward, B. Kahr, Angew. Chem. 2017, 129,10299 –10303]
HYDROGEN BONDED FRAMEWORKS
A typical guanidinium organosulfonate bilayer framework. [T. Adachi, M. D. Ward, Acc. Chem. Res. 2016, 49, 2669 – 2679; K. T. Holman, A. M. Pivovar, J. A. Swift, M. D. Ward, Acc. Chem. Res. 2001, 34, 107
A typical guanidinium organodisulfonate "brick" framework. [T. Adachi, M. D. Ward, Acc. Chem. Res. 2016, 49, 2669 – 2679; K. T. Holman, A. M. Pivovar, J. A. Swift, M. D. Ward, Acc. Chem. Res. 2001, 34, 107]
The guanidinium organosulfonate framework crystallized from 1,3,5-benzenetrisulfonate, illustrating the enforcement of hexagonal symmetry by the tritopic linker and the formation of nanotubes. [T. Adachi, M. D. Ward, Acc. Chem. Res. 2016, 49, 2669 – 2679; K. T. Holman, A. M. Pivovar, J. A. Swift, M. D. Ward, Acc. Chem. Res. 2001, 34, 107]
A polar guandinium organosulfonate framework created from a banana-shaped pillar 1-methyl-3,5-disulfonatebenzene. [T. Adachi, M. D. Ward, Acc. Chem. Res. 2016, 49, 2669 – 2679; K. T. Holman, A. M. Pivovar, J. A. Swift, M. D. Ward, Acc. Chem. Res. 2001, 34, 107]
A cylinder enclosed by a curled hexagonal guanidinium sulfonate network in a "tubular inclusion compound" made from guanidinium p-methylbenzene sulfonate, templated by an aromatic guest. [T. Adachi, M. D. Ward, Acc. Chem. Res. 2016, 49, 2669 – 2679; K. T. Holman, A. M. Pivovar, J. A. Swift, M. D. Ward, Acc. Chem. Res. 2001, 34, 107]