- Post Doctoral
MIT Unit Affiliation:
- Chemical Engineering
Post Doc Sponsor / Advisor:
Date PhD Completed:
Top 3 Areas of Expertise:
I have recently completed my Ph.D. in physics at McGill University. My research involved studying DNA molecules confined in very small tubes in order to measure the loss of entropy due to confinement. Currently I work in the Doyle group at MIT, now studying DNA molecules tied into knots, to learn about the physics of spontaneous unknotting. I also wrote, in my spare time, a paper about falling through the centre of the Earth that was published in the American Journal of Physics and briefly became a world news sensation, with appearances in Forbes, the Times of London, NPR, and the Discovery Channel. I have also been working as a research consultant for a health economics firm, on and off for several years.
Expected End Date of Post Doctoral Position:
Knots in confined DNA
DNA in complex nanofluidic systems
Gravity in planetary interiors
Bubble dynamics for focused ultrasound therapy
A complex nanofluidic device consisting of a slit embedded with an array of nanopit cavities is used to study the physics of confined DNA. By measuring the number of cavities occupied by a molecule in varying geometries, the entropic free energy of confinement and effective molecular width were measured. By measuring the correlation time of contour fluctuations between two pits, the dependence of the dominant relaxation modes on the local free energy landscape was investigated. By measuring the fraction of a molecule occupying single pits of varying size, the effects of excluded volume interactions in cavities were studied. The results were considered in light of a model for the free energy of confinement taking into account semi-flexibility, excluded volume, and entropic elasticity, components of which were developed to understand these experiments.
5 Recent Papers:
Klotz, Alexander R., et al. "Measuring the Confinement Free Energy and Effective Width of Single Polymer Chains via Single-Molecule Tetris." Macromolecules 48.14 (2015): 5028-5033.
Klotz, Alexander R., et al. "Correlated Fluctuations of DNA between Nanofluidic Entropic Traps." Macromolecules 48.13 (2015): 4742-4747.
Klotz, Alexander R. "The gravity tunnel in a non-uniform Earth." American Journal of Physics 83.3 (2015): 231-237.
Klotz, Alexander R. "Bubble dynamics in N dimensions." Physics of Fluids (1994-present) 25.8 (2013): 082109.
Klotz, Alexander R., Hugo B. Brandão, and Walter W. Reisner. "Diffusion Resonance of Nanoconfined Polymers." Macromolecules 45.4 (2012): 2122-2127.