Technicalendar for 01/27/2013 through 02/02/2013

Technicalendar for 01/27/2013 through 02/02/2013

Wednesday, January 30, 2013

Applications of Nanoscale Imaging Methods to Nanomaterials and Biomembranes
9:30 AM (ET)
Location: Bldg. 221, B145
Speaker Name/Affiliation: Dr. Linda Johnston, Group Leader, Nanoscale Measurement, Measurement Science and Standards, National Research Council Canada, Ottawa, ON K1A 0R6
Description: This talk will summarize our group’s efforts in combinations of scanning probe microscopy and fluorescence spectroscopy/microscopy to study nanoscale morphology and properties of both nanomaterials and biomaterials. Due to a recent reorganization with the National Research Council Canada (NRC) our group, Nanoscale Measurement, has been transferred to the Measurement Science and Standards Division, which is composed predominantly of scientists from NRC's former Institute for National Measurement Standards (or the NIST equivalent) in Canada. We are visiting NIST to learn about your relevant programs and discuss possible collaboration. The visit will include me and 3 colleagues: Drs. Shan Zou, Greg Lopinski and Zygmunt Jakubek. If you wish to meet with Linda or her colleagues while they visit NIST, please contact me at x2155.
Contact: Angela R. Hight Walker  x2155
Website: http://www.nrc-cnrc.gc.ca/eng/people/johnston_linda_4164.html

Maintaining Rigor: One Physicist’s Early Career in Technical Consulting and Program Management
2:30 PM (ET)
Location: 220/B365
Speaker Name/Affiliation: Paul Lopata, LPS
Description: In this informal talk, Paul will discuss technical program management as a scientific career path and illustrate this discussion with his own experiences. These experiences include studying quantum sensors as a post-doc at a local research lab, advising clients as a technical consultant at a local company, and working with a team of scientists as a technical program manager in his current position. Themes of this talk include assessing your own proclivities, the importance of communication skills, and understanding the motivations of others. This talk is designed to be accessible to a wide audience – people in the early part of their career (graduate students and post-docs) are particularly encouraged to attend. A chance to meet informally with the speaker, and refreshments, will be available at 2:30 p.m. The talk will start at 3 p.m.
Contact: Neil Zimmerman X 5887

Friday, February 01, 2013

Tension Induces a Base-Paired Overstretched DNA Conformation
10:00 AM (ET)
Location: Building 227, Rm B208
Speaker Name/Affiliation: Niklas Bosaeus, Chalmers University of Technology, Sweden
Description: Mixed-sequence DNA molecules undergo mechanical overstretching by ~70% at 60-70 pN. Since its initial discovery, a debate has arisen as to whether the molecule adopts a new longer base-paired form or simply denatures under the applied tension. Here, we resolve this controversy by using optical tweezers to extend small 60ñ64 bp DNA duplex molecules whose base content can be designed at will. Our results show that when AT content is high (70%), a force-induced denaturation of the DNA helix ensues at 62 pN that is accompanied by an extension of the molecule of ~70%. By contrast, GC-rich sequences (60% GC) are found to undergo a reversible overstretching transition into a distinct form that is characterized by a 51% extension and that remains base-paired. The extension observed in the reversible transition coincides with that produced on DNA by binding recombinases RecA and Rad51, pointing to its possible relevance in homologous recombination. Niklas did his undergraduate studies in biotechnology at Chalmers. He is now a senior graduate student working with DNA stretching using optical tweezers. He has built his own optical tweezers setup that allows for stretching of very short DNA-strands (30 bp). Current experiments are devoted to study DNA overstretching.
Contact: Elizabeth Strychalski  x5951

Nanofluidic Tools for Single DNA Molecule Analysis
11:00 AM (ET)
Location: Building 227, Rm A202
Speaker Name/Affiliation: Prof. Fredrik Westerlund, Chalmers University of Technology, Sweden
Description: We use nanofluidic tools to stretch and visualize single DNA molecules. Nanochannels allow studies of any long DNA molecule in a high throughput fashion. I will present our resent progress in three separate but potentially interconnected subprojects. We present a one step method to map single DNA molecules with kbp resolution based on competitive binding between YOYO-1 and the AT-specific drug netropsin. Since the netropsin will preferably bind to AT-rich regions, the YOYO-1 will to a larger extent bind to GC-rich regions and the fluorescence intensity along the DNA will reflect the local GC/AT ratio with ~1kbp resolution. I will present results on model DNA as well as discuss potential us in future applications with potential clinical impact. In a more fundamental project we study how YOYO-1 itself affects the physical properties of confined DNA. We do so by using the intrinsic inhomogeneity when YOYO stains to obtain a vastly increased resolution compared to traditional staining protocols. A long-term goal of the group is to use the nanochannels for studying DNA-protein interactions. We have introduced lipid bilayers as a passivation coating for nanofluidic channels that is up to two orders of magnitude more efficient in preventing sticking to the channel walls compared to standard BSA-passivation. We show that the coating allows us to study DNA-RecA filaments during an extended time. We have thus opened up the door for future use of nanochannels as a tool to study the physics of DNA-protein complexes. Fredrik did his undergraduate and graduate studies at Chalmers. The PhD project was devoted to spectroscopic studies of DNA-ligand interactions and the PhD was awarded in 2006. He then did a 2.5 years post doc at the Nano-Science Center at the University of Copenhagen studying optical properties of organic thin films and also gold nanoparticle chemistry for single molecule electronics. In 2009-2010 he spent one year with Prof. J. Tegenfeldt at Gothenburg University studying DNA under strong confinement. Fredrik is currently an assistant professor at Chalmers studying DNA using nanofluidic tools. Focus is on a recently developed mapping method for single DNA molecules and on studies of DNA-protein interactions.
Contact: Elizabeth Strychalski  x5951

NIST Colloquium -- Dave Wineland -- Superposition, Entanglement, and Raising Schrödinger’s Cat
1:00 PM (ET)
Location: Boulder Auditorium with VTC to Gaithersburg 101 Red Auditorium
Speaker Name/Affiliation: NIST Nobel Laureate Dave Wineland
Description: Research on precise control of quantum systems occurs in many labs throughout the world, for fundamental research, new measurement techniques, and more recently for quantum information processing. NIST Nobel Laureate Dave Wineland will briefly describe experiments on quantum state manipulation in the NIST Ion Storage Group and other research groups, which serve as examples of similar work being performed with many other atomic, molecular and optical (AMO) and condensed matter systems at NIST and across the world. This talk is in part the “story” of his involvement that was presented at the 2012 Nobel Prize ceremonies, with some additional comments specific to NIST.
Accessibility: Anyone outside NIST wishing to attend must be sponsored by a NIST employee and receive a visitor badge. For more information, contact Stephanie Shaw at 301-975-2667. Colloquia are videotaped and available in the NIST Research Library.
Contact: Heather Evans  301-975-4525
Sponsored by: Heather Evans