Technicalendar for 02/17/2013 through 02/23/2013

Technicalendar for 02/17/2013 through 02/23/2013

Tuesday, February 19, 2013

"Effects of Surface Energies on Phase Equilibria in Nanoscale Materials"
11:00 AM (ET)
Location: Bldg. 223, B307
Speaker Name/Affiliation: Prof. Alexandra Navrotsky, UC Davis
Description: Polymorphism, dehydration and decarbonation reactions, and redox phase boundaries change substantially in nanoscale materials because of differences in surface energies of reactants and products. We measure surface energies of both dry and wet oxide surfaces by combining high temperature oxide melt solution caloriemetry and water vapor adsorption calorimetry. The experimental values generally support those obtained by DFT calculations and show considerable systematics with structure type. When two phase assemblages differ in surface energy by 2 J/m2, which is not uncommon, the free energy of a reaction can be changed by as much as 30 kJ/mol for 10 nm particles. This results in changes of as much as 100 K in dehydration/decarbonation temperatures and 2-4 log(pO2) units in redox reactions. In some cases, new phase assemblages can be stabilized at the nanoscale. Examples from transition metal oxide equilibria are given.
Contact: Terrell Vanderah  x5785

Wednesday, February 20, 2013

Novel Emergent States in Electronic Materials
10:45 AM (ET)
Location: Bldg. 235, Rm. K04B
Speaker Name/Affiliation: Nick Butch, Lawrence Livermore National Laboratory
Description: The interactions between electrons in a material can lead to collective behavior qualitatively different from that of the constituent electrons themselves. Examples range from superconductivity to more exotic objects such as magnetic monopoles. The speaker will discuss two cases of recent interest with rather different underpinnings. In topological insulators, the surfaces of an electrical insulator support symmetry-protected metallic states with novel properties, the most striking of which are chirality and protection against localization. He will describe efforts to grapple with the experimental challenges of isolating the conduction of surface states in the archetypal topological insulator Bi2Se3. He'll also touch on expanding the search for topological surface states in other promising materials. The interesting behavior of strongly correlated electrons derives from a complicated interplay of localized and itinerant electronic states. One of the oldest mysteries in this realm is the hidden order state of the heavy fermion superconductor URu2Si2, the nature of which remains uncertain after 25 years of study. Nick will describe recent experimental developments that suggest an unusual twist: electrons may independently break the rotational symmetry of the underlying crystal lattice. References: N. P. Butch, et al, Phys. Rev. B 81, 241301(R) (2010); arXiv:1003.2382v1. N. P. Butch, et al, Phys. Rev. B 84, 220504(R) (2011); arXiv:1109.0979v2. X. Zhang, et al, arXiv:1211.5532. N. P. Butch, et al, arXiv:1212.6238.
Contact: Craig Brown  301-975-5434
Sponsored by: Craig Brown

Thursday, February 21, 2013

Self-Assembled Systems and Gels for Conservation of Cultural Heritage
11:45 AM (ET)
Location: Bldg. 235, Rm. K04B
Speaker Name/Affiliation: Piero Baglioni, University of Florence
Description: New perspectives have been opened by the application of colloids, and in particular of self-assembling systems and nanoparticles, to Conservation, generating a breakthrough in the development of innovative tools for the conservation and preservation of cultural heritage. This contribution is an overview of the most recent methodologies developed in the Conservation field, focusing on amphiphilic systems, and gels. The speaker will report on two recently developed systems and on their application for the cleaning of works of art: i) The characterization of two systems, EAPC and XYL, which have shown good to optimal performances in the removal of organic polymers from wall paintings. EAPC is a five-components fluid composed of water, sodium dodecylsulfate (SDS), 1-pentanol (PeOH), propylene carbonate (PC), and ethyl acetate (EA), while XYL is a “ classical ” o/w microemulsion where p-xylene droplets are stabilized in water by SDS and PeOH. Small-angle neutron scattering (SANS) with contrast variation is used to infer a detailed picture of the structure of these complex fluids. They found that the composition and the structure at the nanoscale determine the capability of removing a broad range of different polymer coatings from porous materials. ii) An innovative hydrogel based on semi-interpenetrating poly(2-hydroxyethyl methacrylate)/polyvinylpyrrolidone networks with suitable hydrophilicity, water retention properties, and required mechanical strength to avoid residues after the cleaning the works of art. This family of gels is able to confine water or water based complex fluid, and has outstanding cleaning capacity for water-sensitive works of art, and in particular for watercolor paintings that are extremely difficult to clean with conventional methods. References 1) Giorgi, R.; Baglioni, M.; Berti, D.; Baglioni, P. New Methodologies for the Conservation of Cultural Heritage: Micellar Solutions, Microemulsions, and Hydroxide Nanoparticles. Acc. Chem. Res. 2010, 43, 695– 704. 2) Baglioni, M.; Rengstl, D.; Berti, D.; Bonini, M.; Giorgi, R.; Baglioni, P. Removal of acrylic coatings from works of art by means of nanofluids: understanding the mechanism at the nanoscale. Nanoscale 2010, 2, 1723– 1732. 3) Baglioni, M.; Giorgi, R.; Berti, D.; Baglioni, P. Smart cleaning of cultural heritage: a new challenge for soft nanoscience. Nanoscale 2012, 4, 42– 53. 4) Baglioni, M.; Berti, D.; Teixeira, J.; Giorgi, R.; Baglioni, P. Nanostructured Surfactant-Based Systems for the Removal of Polymers from Wall Paintings: a SANS Study. Langmuir, 2012, 28, 15193– 15202. 5) Carretti, E.; Fratini, E.; Berti, D.; Dei, L.; Baglioni, P. Nanoscience for Art Conservation: Oil-in-Water Microemulsions Embedded in a Polymeric Network for the Cleaning of Works of Art. Angew. Chem. Int. Ed. 2009, 48, 8966?8969.
Contact: Yun Liu  301-975-6235
Sponsored by: Yun Liu

Friday, February 22, 2013

NIST Colloquium -- Keith Baggerly -- When is Reproducibility an Ethical Issue?
10:30 AM (ET)
Location: 101/Green Auditorium with VTC to Boulder Rm 1-1107
Speaker Name/Affiliation: Keith Baggerly -- MD Anderson Cancer Center
Description: Modern high-throughput biological assays let us ask detailed questions about how diseases operate, and promise to let us personalize therapy. Careful data processing is essential, because our intuition about what the answers “should” look like is very poor when we have to juggle thousands of things at once. When documentation of such processing is absent, we must apply “forensic bioinformatics” to work from the raw data and reported results to infer what the methods must have been. Dr. Baggerly will present several case studies where simple errors may have put patients at risk. This work has been covered both on the front page of the New York Times and by CBS’ 60 Minutes, and has prompted several journals to revisit the types of information that must accompany publications. Dr. Baggerly will share his perspective on steps that should be taken to avoid these errors and present some important lessons that can be applied to NIST’s efforts in biology, large data sets, statistics, and more.
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
Website: https://cspot-run2.nist.gov/public_affairs/colloquia/20130222.cfm