Latest News from the Welsher Lab

Duke Chemistry Virtual Open House

Want to join our team to capture fast processes in chemical and biological systems through advanced 3D microscopy? Apply to Duke Chemistry! You can learn more about the program and meet some members of our team at the upcoming Duke Chemistry Virtual Open House on Wednesday, November 1nd, 3-5 PM ET. Registration closes October 30th.

Register here:

Interested in rotations?

Welcome to the new cohort of Duke Chemistry graduate students!

Are you interested in capturing biology and chemistry at speeds and scales previously impossible? Want to learn more about the initial contacts of viruses with host tissue or analyze the behavior of single molecules in complex environments? Like to build things or work with your hands? Like to code or want to learn how to code? If any of these fit you, come do a rotation with us! If you want more information, just contact Kevin directly. For more information on current projects, head over to the Research Overview page.

We have two “subgroup” meetings that prospective students are welcome to join. All meetings held in FFSC 2219:

Wednesdays 10:15-11:30 AM: Single-molecule tracking methodology (Starting 8/30)

Fridays 10:15-11:30 AM: Virus tracking/polymer growth (Starting 9/8, no meeting 9/1)

Larger group meetings/journal club will be held on Wednesdays at 5 PM starting 9/6. Pizza provided!

Interested students are always welcome to attend group meetings, whether in an official rotation or not!

Congrats to Dr. Chen Zhang!!!

Congrats to Dr. Chen Zhang, who successfully defended his thesis entitled “Improved Localization Precision in 3D Single-Particle Localization Microscopy via Off-Center Sampling and Its Applications in Living Systems!” Dr. Zhang took a pioneering role in the group in thinking about how to maximize the information yield of photons in 3D-SMART. Dr. Zhang will take his talents in coding and data handling on to a Masters program in computer science here at Duke! Best of luck, Chen!

Shoutout to Alexis for the very on-theme and delicious post defense snacks!

More robust single-molecule tracking with galvo mirrors

Dr. Xiaochen Tan and team recently demonstrated that real-time 3D single-molecule tracking performance is dramatically improved, both in terms of tracking precision and stability, by replacing a piezoelectric nanopositioner with high-speed galvo steering mirrors. While prior reports of active-feedback tracking have used piezoelectric stages or galvo steering mirrors, Dr. Tan’s work is the first to do a direct comparison, showing clearly the advantage of galvo steering mirrors due to their more rapid response time (~200 μsec) compared to the piezo stage implementation (>1 msec). This work suggests that for real-time 3D single-particle tracking to progress to real-time 3D single-molecule tracking, the piezo technology need to be replaced by faster-responding optical elements. Well done, Xiaochen, Shangguo, Stacey, Chen, and Alexis!


Read the paper here:

Alexis wins NSF Graduate Research Fellowship!!!

Congratulations to second-year graduate student Alexis Johnson for being selected for the prestigious Graduate Research Fellowship from the National Science Foundation! The NSF GRF is a highly competitive and selective program that highlights top graduate students from across the US. This award recognizes Alexis’s stellar record in research and academics, as well as her tremendous potential as a scientist. This award will fund her research on applying active control within real-time 3D single particle tracking. Way to go, Alexis!!!

COBWEBS – Now in 3D!

In a recent Proceeding of the SPIE, Stacey demonstrated an extension of COBWEBS (Combined Online Bayesian Windowed Estimation of Background and Signal) to the third dimension. In simulated trajectories, this 3D variant of COBWEBS enables continuous tracking of freely diffusing objects in heterogeneous environments with background levels several fold larger than the actual signal. The extension to 3D is an important step towards an experimental implementation of COBWEBS, which will dramatically expand the scope of what is possible with active-feedback tracking.

Read the full paper here: Niver, A. J.; Welsher, K. D. Using COBWEBS for 3D active-feedback tracking of freely diffusing particles in tricky environments. Proc.SPIE 12386, 1238605, (2023).

See Stacey’s full talk from Photonics West on the Presentations tab or below:

Congratulations to Dr. Xiaochen Tan!!!

Dr. Xiaochen Tan has successfully defended her thesis entitled “Advances in Real-time 3D Single Particle Tracking Microscopy for Particle-by-Particle In-Situ Characterization of the Nanoparticle Protein Corona.” Dr. Tan is the third PhD from the group. We are delighted that she will be staying on with the group as a postdoc where she will continue to lead our high-speed 3D tracking efforts. Congratulations, Dr. Tan!!!

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