A rectangular bacterial transportation system (50 x 100 sq. micron meters) in microfluidic environments reveals rotational velocity of 0.39 rad/s before UV exposure. The system stops withing the first second of a 7 seconds UV exposure. Rotation again resumes within 1 second and rotation of 0.47 rad/s is observed. After a second UV exposure and stop, rotational motion again resumes [PDF].

Transmission electron microscope (TEM) tomography, based on tilt series, can be used to create three-dimensional structure of solid-state nanopore, which is formed by high intensity of electron beam. After collecting the tilted (- 45 degree to 45 degree) 2-D images, we can reconstructure the 3-D nanopore structure using an advanced back-projection algorithm in Automated Reconstruction of Tomographic Tilt Series (ARTS). With single-digit nanometer pores, we are able to investigate ssDNA/dsDNA/RNA kinetics as well as DNA sequencing at single base resolution. The pore shown in this video has a 8 nm diameter [PDF].

Our objective is to understand and model the mechanics of bacterial flagellar bundling. Full-scale flagella are 10 micron meters in length, 20 nm in diameter, and turn at a rate of 100 Hz. To accurately simulate bundling at a more easily observable scale, we built a scale model in which 20 cm long helices are rotated in 100,000 cp silicone oil (poly-di-methyl-siloxane). The highly viscous oil ensures an appropriately low Reynolds number. We developed a macroscale particle image velocimetry (PIV) system to measure the full-field velocity distribution for rotating rigid helices and rotating flexible helices [PDF].