CHESS DMR-0936384 2013

Highly organized fusion of nanoparticles on heating Joel Brock, Cornell University, DMR 0936384

Small-angle X-ray scattering intensity as a function of temperature during in situ thermal processing of sub-2 nm dodecanethiol-capped Au nanocrystals.

Brian W. Goodfellow, Michael R. Rasch, Colin M. Hessel, Reken N. Patel, Detlef-M. Smilgies, and Brian A. Korgel: "Ordered Structure Rearrangements In Heated Gold Nanocrystal Superlattices", Nano Lett. (accepted October 2013).

Intellectual Merit: Ostwald ripening is a familiar effect – think of small water droplet condensing on a cold window pane. Sooner or later larger droplets form that will grow at the expanse of the smaller ones. Now imagine this random process proceeding in a highly organized way and with formation of symmetric patterns – such a behavior would seem rather unusual. The Korgel team at the University of Texas at Austin used X-ray studies at the D1 station at CHESS to find that small gold nanoparticles do exactly that, even in three dimensions. They observed that 2 nm gold nanoparticles form a body-centered cubic lattice when dropcast on a silicon wafer or plastic foil. After heating to above 140C, new diffraction features appear, indicating a new HCP crystal phase has formed. Heating caused some self-organized ripening with particles only fusingat certain positions in the original superlattice, and then at elevated temperatures forming a binary superlattice of larger fused gold nanocrystals. This result is surprising because most superlattices are delicate and fall apart with minor perturbations – these display a rather rich set of organized structures.

CHESS DMR-0936384 2013

TEM and Fourier transforms with model representations of supercubic (G-I) and binary hexagonal (J-L) superlattice phases of sub-2 nm dodecanethiol-capped Au nanocrystals.

Broader Impacts: Ordered assemblies of ligand-stabilized nanocrystals, or superlattices, are interesting because of their unique optical and electronic properties. Nanocrystals in the quantum size regime, less than 10 nm in diameter, can be produced with uniform size distributions, exhibiting physical properties that are fundamentally different from their bulk counterparts and can be tuned synthetically by manipulating the particle size. In bulk, collective electronic coupling between neighboring nanocrystals gives rise to new physical properties, hence these self-assembled materials have been called “artificial solids” or “metamaterials” since nanocrystals instead of atoms serve as building blocks. These superlattices can also exhibit significant structural polymorphism. Korgel’s experiments reveal a conceptual link between the self-assembly of nanocrystal superlattices and microphase-separated amphiphilic molecules like diblock copolymers.

Brian W. Goodfellow, Michael R. Rasch, Colin M. Hessel, Reken N. Patel, Detlef-M. Smilgies, and Brian A. Korgel: "Ordered Structure Rearrangements In Heated Gold Nanocrystal Superlattices", Nano Lett. (accepted October 2013).

Highly organized fusion of nanoparticles on heating Joel Brock, Cornell University, DMR 0936384

CHESS DMR-0936384 2013

It’s Flu Season: new broadly effective flu drugsJoel Brock, Cornell University, DMR 0936384

Discovery of a third active site metal (M3 in lower right). Metal-coordinating bonds are depicted as black dashed lines and hydrogen bonds as blue dashed lines.

Bauman, J.D., Patel, D., Baker, S.F., Vijayan, R. S. K., Xiang, A., Parhi, A.K., Martinez-Sobrido, L., LaVoie, E.J., Das, K., Arnold, E. (2013), “Crystallographic fragment screening and structure-based optimization yields a new class of influenza endonuclease inhibitors”, ACS Chem. Biol. 2013 Sept. 13 [Epub ahead of print]

Intellectual Merit: A group of researchers from Rutgers University led by Dr. E. Arnold has discovered and developed a new class of inhibitors targeting influenza endonuclease activity of the viral polymerase. Previous studies have determined that the endonuclease active site resides in the N-terminal domain of the polymerase acidic protein subunit (PAN), and crystal structures of PAN have revealed a deep active site cleft containing multiple subpockets that can be targeted for drug design. X-Ray crystallography experiments were largely conducted at CHESS F1 beamline and NSLS at Brookhaven National Laboratory. High-resolution crystallographic data confirmed the binding of a metal ion in the M3 site in the presence of an inhibitor; this observation is potentially relevant to the mechanism of endonuclease activity and may play a role in the urgent need for developing new broadly effective flu drugs.

CHESS DMR-0936384 2013

Calculated electrostatic potential surface of the active site cleft of PAN, with different subpockets labeled. Binding of two different inhibitors is shown: a carboximide derivative with 3 chelating groups [1] (gray) and one of the group studied in the new work (yellow)

Bauman, J.D., Patel, D., Baker, S.F., Vijayan, R. S. K., Xiang, A., Parhi, A.K., Martinez-Sobrido, L., LaVoie, E.J., Das, K., Arnold, E. (2013), “Crystallographic fragment screening and structure-based optimization yields a new class of influenza endonuclease inhibitors”, ACS Chem. Biol. 2013 Sept. 13 [Epub ahead of print]

Broader Impacts: Influenza is a severe infectious disease, caused by RNA viruses, that can spread around the world in seasonal epidemics. Moreover, influenza can become pandemic when a new strain of the virus appears in humans, as has happened several time in the 20-th century. The primary defense against influenza is vaccination in the form of either inactivated or live attenuated viruses. However, in the event of a pandemic, timely production of vaccines, together with their partial efficacy, present serious challenges to the world's health institutions. The recent outbreak of an unusual H7N9 strain, the emergence of drug-resistant variants of influenza A strain, and the adaptation of H5N1 for human-to-human transmission emphasize the urgent need for developing new broadly effective flu drugs. A group of researchers from Rutgers University led by Dr. E. Arnold has discovered a new class of inhibitors targeting influenza endonuclease activity of the viral polymerase and potential drug design.

It’s Flu Season: new broadly effective flu drugsJoel Brock, Cornell University, DMR 0936384

CHESS DMR-0936384 2013

CHESS Education Program “Junk Genies” wins big at 2013 Maker Faire

Joel Brock, Cornell University, DMR 0936384

Cornell physics graduate student Jennifer Chu talks to fair-goers about exhibits.

http://makezine.com/2013/09/22/physics-experiments-from-upcycled-appliances/

The CHESS outreach program traveled to the 2013 Maker Faire at the New York Hall of Science this fall. The Maker Faire is an annual event held by Maker Media (publisher of MAKE Magazine). Many of the exhibits are interactive, with a focus on future technology and do-it-yourself projects. CHESS’ booth, Physics Experiments from Upcycled Appliances, displayed numerous exhibits created by their “Junk Genies” demonstrating interesting science phenomenon. The “Junk Genies” are comprised of Ithaca 9th and 10th graders who participate in local after-school programs focused on science. The students repurposed things to provide scientific insight--creating exhibits literally out of junk. Some of the students even attended the fair to help demonstrate their creations! The upcycled exhibits creatively demonstrate a range of science concepts by repurposing appliances no longer needed for their original purpose. The “Junk Genies” turned an old microwave into a light show by placing neon gas-filled bulbs on the rotating tray; as the tray rotates while the microwave runs, the microwaves excite the neon gas, lighting the bulbs. Hundreds of excited and engaged visitors, both young and old, were encouraged to interact with the hands-on exhibits. Our booth earned both Educator’s Choice and three Editor’s Choice awards.