Scott L. Diamond, PhD
Arthur E. Humphrey Professor of
Chemical and Biomolecular Engineering
University of Pennsylvania
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Dec. 4, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Excessive bleeding and clotting represent the two extremes of blood function that often concern patients and their doctors. Hundreds of spatiotemporal reactions proceed within activating and aggregating platelets and the polymerizing plasma as blood clots under flow. Microfluidic devices are ideal for recreating transport physics and hemodynamic forces. We have validated several devices to study hemophilia, combinatorial platelet receptor function, drug responses, platelet quorum sensing, and von Willebrand Factor (vWF) assembly in extreme stenotic flows. With multi-scale simulation of reactive blood clotting under flow, it is now possible to predict disease risks using patient-specific hemodynamics and blood biochemistry/pharmacology. This sets the stage for point-of-care microfluidic diagnostics in emerging areas of neonatology, trauma surgery, and angiography.

Biosketch:
Scott L. Diamond, Ph.D. (B.S., Cornell University 1986; Ph.D., Rice University 1990) Dr. Diamond researches biotechnologies in several key areas: endothelial mechanobiology, blood clot dissolving therapies, blood systems biology, nonviral gene therapy, and high throughput drug discovery. He has produced over 230 publications and patents and has served on advisory committees to NSF, NIH, AHA, and NASA, and has consulted extensively for industry and government. Diamond is the recipient of the NSF National Young Investigator Award, the NIH FIRST Award, the American Heart Association Established Investigator Award, the AIChE Allan P. Colburn Award, and the George Heilmeier Excellence in Research Award. Dr. Diamond is an elected Fellow of the Biomedical Engineering Society (BMES) and the American Institute for Medicine and Biological Engineering (AIMBE). Currently, Dr. Diamond is the Director of the Penn Biotechnology Program, with more than 1000 alumni.

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Professor Stefan Zauscher
Department of Mechanical Engineering and Materials Science
Duke University
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Nov. 13, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

The use of DNA as a polymeric building material transcends its function in biology and is exciting in bionanotechnology for applications ranging from biosensing, to diagnostics, and to targeted drug delivery. Hence, the efficient and precise synthesis of high molecular weight DNA materials has become key to advance DNA bionanotechnology. In the first part of my talk I report on how we exploit a template-independent DNA polymerase —terminal deoxynucleotidyl transferase (TdT)— to catalyze the polymerization of 2’-deoxyribonucleoside 5’-triphosphates (dNTP, monomer) from the 3’-hydroxyl group of an oligodeoxyribonucleotide (initiator). We found that the reaction kinetics follows a “living” chain-growth polycondensation mechanism, and that like in living polymerizations, the molecular weight of the final product is determined by the starting molar ratio of monomer to initiator. Our synthesis approach can incorporate a wide range of unnatural dNTPs into the growing chain which allows us to synthesize multifunctional block- copolymers that can self-assemble into micellar structures for drug delivery applications.

In the second part of my talk I report on recent activities in developing a new class of acoustic shear wave resonator sensors (SWRS). I will show that by confining fluid into small, rigid channels oriented perpendicularly to the shear direction of the SWRS, we can manipulate liquid to behave as a lossless layer and thus perform precise mass measurements of the confined liquid. Canceling viscous effects in µ-fluidic SWRS not only enhances their mass resolution in liquid to levels observed in air/vacuum, but also enables efficient device miniaturization. Combined with the extremely small volume requirements for sensing (~nL), I will show that µ-luidic SWRS can overcome current barriers for their widespread use in diagnostic sensing and point of care applications.

Link to Zauscher Lab Research Web Page

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Kui Tan, PhD
Research Scientist
The University of Texas at Dallas
Department of Materials Science and Engineering
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Nov. 20, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Understanding co-adsorption in nanoporous materials such as metal organic frameworks (MOFs) is important for most applications, since these materials are seldom used exclusively for pure gases and are prone to gas contamination. Co-adsorption, however, leads to a variety of processes that complicate the analysis, such as molecular competition for adsorption and diffusion. Due to a lack of in situ characterization techniques within these 3D nanoporous structures, these processes remain largely unknown. Our pioneering studies, which combine in situ infrared spectroscopy and ab initio calculations, have yielded several unexpected findings with respect to the principles governing co-adsorption. For example, binding energy alone is not a sufficient indicator for prediction of molecular exchange and stability. Instead, the occupation of the active sorption sites could be governed by kinetics in a nanoconfined space. We have also identified an unusual synergistic effect involving co-adsorption of NH3 and H2O with a variety of small gases (e.g., CO, CO2, SO2) in a prototypical metal organic framework (MOF) material, i.e., MOF-74. This phenomenon is not due to guest-guest binding, which is usually regarded as a “cooperative binding effect”, but is instead the result of an increase in diffusion barrier for these small molecules. The aforementioned findings inspired us to invent a new strategy for retaining a variety of weakly adsorbing molecules inside the MOFs materials by in situ coating of their external surfaces with ethylenediamine (EDA), a type of sticky molecule. Interestingly, the opening size and breathing rate of the EDA network can be finely tuned by varying the temperature, while accounting for the observed activated adsorption at elevated temperatures. The discovery of this novel temperature-tunable diffusion barrier suggests a new avenue for
tailoring selective adsorption by thermally tuning the surface barrier.

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Professor Natalia Khuri
Department of Computer Science
Wake Forest University
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Nov. 6, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Solute carrier (SLC) transporters – a family of more than 400 membrane-bound proteins facilitating the transport of ions, drugs, and metabolites across biological membranes – have important roles in physiological processes. Several classes of marketed drugs target SLC transporters, and human genetic studies have provided insight into their roles in both rare and common diseases. Recent technological advances in biophysics and chemical biology allow better characterization of SLC pharmacology. We will describe computational approaches and in vitro experiments to study SLC-mediated drug-drug and drug-nutrient interactions with a focus on two intestinal transporters, the organic anion transporting polypeptide OATP2B1 and the thiamine transporter ThTR-2.

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Professor Olivier Delaire
Department of Mechanical Engineering and Materials Science
Duke University
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 30, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

A detailed view of atomic motions in materials is needed to refine microscopic theories of transport and thermodynamics, and to design next-generation energy materials. In particular, the behavior of atomic vibrations (phonons) is key to rationalize numerous functional properties, ranging from ferroelectrics for sonar, to superionics for safer solid batteries, to thermoelectrics for waste-heat harvesting, or metal-insulator transitions for ultrafast transistors. Near phase transitions associated with phonon instabilities, one needs to properly account for the effect of strong anharmonicity, which disrupts the quasiharmonic phonon gas model through large phonon-phonon coupling terms. Large phonon amplitudes can also amplify the electron-phonon interaction and lead to renormalization of a material’s electronic structure. These interactions, while often neglected in textbooks and traditional studies, could open the door to further tuning of materials properties for improved functionality.

This presentation will highlight results from our investigations of atomic dynamics in several classes of materials impacted by lattice instabilities, such as ferroelectrics and multiferroics (EuTiO3, YMnO3) [1], thermoelectrics (PbTe, SnSe) [2-4], superionic conductors [5], and VO2 across its metal insulator transition [6,7]. Our group takes advantage of advances in modern neutron and x-ray instrumentation, which have revolutionized our ability to probe atomic dynamics. By mapping phonon spectral functions throughout reciprocal space, phonon anharmonicity and couplings to other degrees of freedom can now be revealed in great detail. Such mode-resolved investigations bring direct insights into phonon scattering mechanisms, including anharmonicity, electron-phonon coupling, spin-phonon coupling, or scattering by defects and nanostructures. Increasingly, first-principles simulations of atomic dynamics enable the quantitative rationalization of these effects, for example with ab-initio molecular dynamics simulations or anharmonic renormalization techniques at finite-temperature, and our group systematically integrates such modeling with our scattering experiments. The presentation will conclude with some possible scientific opportunities.

[1] D. Bansal, J. L. Niedziela, R. Sinclair, V. O. Garlea, D. L. Abernathy, S. Chi, Y. Ren, H. Zhou, and O. Delaire, “Momentum-resolved observations of the phonon instability driving geometric improper ferroelectricity in yttrium manganite”, Nature Communications 9, 15 (2018).
[2] O. Delaire, J. Ma, K. Marty, A. F. May, M. A. McGuire, M.-H. Du, D. J. Singh, A. Podlesnyak, G. Ehlers, M. Lumsden, B. C. Sales, “Giant Anharmonic Phonon Scattering in PbTe”, Nature Materials 10, 614 (2011).
[3] C.W. Li, O. Hellman, J. Ma, A.F. May, H.B. Cao, X. Chen, A.D. Christianson, G. Ehlers, D.J. Singh, B.C. Sales, and O. Delaire, “Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics”, Physical Review Letters 112, 175501 (2014).
[4] C.W. Li,* J. Hong,* A.F. May, D. Bansal, S. Chi, T. Hong, G. Ehlers and O. Delaire, “Orbitally-driven giant phonon anharmonicity in SnSe”, Nature Physics 11, 1063 (2015).
[5] J. L. Niedziela, D. Bansal, A. F. May, J. Ding, T. Lanigan-Atkins, G. Ehlers, D. L. Abernathy, A. Said & O. Delaire, “Selective Breakdown of Phonon Quasiparticles across Superionic Transition in CuCrSe2”, Nature Physics, 15, 73–78 (2019)
[6] J. D. Budai*, J. Hong*, M. E. Manley, E. D. Specht, C. W. Li, J. Z. Tischler, D. L. Abernathy, A. H. Said, B. M. Leu, L. A. Boatner, R. J. McQueeney, and O. Delaire, “Metallization of vanadium dioxide driven by large phonon entropy”, Nature 515, 535–539 (2014).
[7] S. Lee, et al., “Anomalously low electronic thermal conductivity in metallic vanadium dioxide” Science, 355 (6323): 371 (2017).

Funding from US DOE, Office of Basic Energy Sciences, Materials Science and Engineering Division.
Link to Delaire Research Group Web Page

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Weronika Wolszczak, PhD
Technical University of Delft
Wake Forest University Postdoc 2019-2021
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 23, 2019, at 3:00 PM


There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.


ABSTRACT

This talk will address two research topics which were bases of my Master and PhD theses.

The search for new physics at high energies was motivation for building the Large Hadron Collider (LHC), the world’s most powerful man-made particle accelerator. Five experiments have been constructed along the accelerator tunnel. The two largest ones, ATLAS (A Toroidal LHC Apparatus) and CMS (Compact Muon Solenoid), are multi-purpose detectors. The Nobel Prize in Physics 2013 was awarded jointly to François Englert and Peter W. Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.”. Here I will present my contribution to the CMS experiment and research before the discovery of the Higgs boson.

Scintillators are important materials for ionizing radiation detection.

As determined by photon detection statistics, the ultimate energy resolution for γ‐photon detection can only be approached for materials that show a perfect proportional response with γ‐energy. A large amount of research has resulted in the discovery of highly proportional materials, such as LaBr3:Ce3+,Sr2+, SrI2:Eu2+ and CsBa2I5:Eu2+. However, the resolution is still far from the theoretical limit. In this part I will discuss my research on non-proportionality of scintillation response and new strategies to improve energy resolution.

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WFU Physics Career Advising Event

SPEAKER:  Dr. Malcolm Chisholm, Chief Innovation Officer for First San Francisco Partners

TIME: Thursday, October 17, 2019, from 12:30 – 1:30 PM

PLACE: Olin Physical Laboratory, Lounge


Lunch will be provided. All interested persons are cordially invited to attend.


As the Chief Innovation Officer for First San Francisco Partners, Dr. Chisholm brings more than 25 years’ experience in data management, having worked in a variety of sectors including finance, insurance, manufacturing, government, defense and intelligence, pharmaceuticals and retail. His deep experience spans specializations in data governance, master/reference data management, metadata engineering, business rules management/execution, data architecture and design, and the organization of Enterprise Information Management.

Dr. Chisholm is a well-known presenter at conferences in the US and Europe, writes columns in trade journals, and has authored the books: Managing Reference Data in Enterprise Databases; How to Build a Business Rules Engine; and Definitions in Information Management. In 2011, Dr. Chisholm was presented with the prestigious Data Management Association International Professional Achievement Award for contributions to Master Data Management. He holds an M.A. from the University of Oxford and a Ph.D. from the University of Bristol.

As a world-renowned expert in data management and data analysis Dr. Chisholm will discuss career options with students who have strong backgrounds in mathematics and strong analytical skills.

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Dr. Malcolm Chisholm
Chief Innovation Officer
First San Francisco Partners
Oakland, CA
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 16, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

“Big Data” is a term that emerged in the early 2000’s to describe both datasets at a very large scale and a set of technologies that could manage these datasets. Since the emergence of Big Data its significance has grown and seems set to expand with anticipated future technological advances. This presentation explores the significance of Big Data in the general academic context, principally why it should matter to both students and researchers. With respect to students, the economic shifts that have occurred due to Big Data in the past 10 years need to be understood if students are to quickly take their place in the workforce without the need for extensive additional training. For researchers, the promise of Big Data must be balanced with the need for sound methodological approaches that may mean extensions of the scientific method that have not be relevant in the past. The presentation will focus on:

· What Big Data is and how it differs to traditional types of data and related technologies

· How the private sector and government have responded to the emergence of Big Data, and how this may affect students’ employment prospects

· The opportunities for research provided by Big Data, along with the increased requirements for data governance, metadata management

· Challenges that have resulted from the widespread adoption of Big Data

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Professor Troy Stich
Department of Chemistry
Wake Forest University
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 9, 2019, at 3:00 PM


There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.


ABSTRACT

The radical SAM (S-adenosyl-L-methionine) superfamily of enzymes catalyzes a dizzying array of chemistries triggered by reductive cleavage of SAM to yield the primary carbon radical 5′-deoxyadenosyl (5’dAdo●). 5’dAdo● can pluck off H-atoms with bond dissociation enthalpies <105 kcal/mol from substrate molecules to initiate carbon skeleton rearrangements. We hypothesize that amino acids within the active site, a triose phosphate isomerase (TIM) barrel, are key in conducting these rearrangements down the evolutionary-designed path. Our research effort employs a combined biochemical, spectroscopic, and computational approach to determine atomic level details of these mechanisms. We further use substrate analogs that can slow or halt the chemistry at key points, allowing us to verify mechanistic hypotheses. Today, I will present a few examples that illustrate our progress toward unveiling the factors that control these exotic reactions.

Link to Professor Stich’s web page

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Professor Dmitri Kilin
Department of Chemistry and Biochemistry
North Dakota State University
Fargo, ND
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 2, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Colloidal semiconductor nanostructures demonstrate favorable tuning of the optoelectronic properties facilitated by quantum confinements. The interpretation, understanding, and optimization of fabrication and characterization of nanostructures are assisted by computational modeling of excited state dynamics at the atomistic level. Dynamics of heat and light activated processes is contributed by simultaneous evolution of (I) nuclear and (II) electronic degrees of freedom. (I) The dynamics in nuclear degrees of freedom is dictated by heights of activation barriers and mechanisms to overcome such barriers, including tunneling. A recently developed time dependent excited state molecular dynamics (TDESMD), has been applied to investigate overcoming of barriers in polymerization reactions for cyclohexasilane (Si6H12) precursors for fabrication of solid silicon nanoparticles. (II) Photoinduced dynamics of electronic degrees of freedom is useful in computational characterization of semiconductor nanostructures. Two important factors provide contribution to efficiency, quantum yield (QY), and line-shape of photoluminescence (PL) signal in photoexcited colloidal nanostructures: (a) cascading process of hot carriers cooling via non-adiabatic dissipation of electronic excitation energy to lattice vibrations and (b) distribution of transition energy and oscillator strength in an ensemble, also related to exciton-to-phonon coupling, providing quantitative way to assess thermal broadening of the PL lineshape. The first principles modeling demonstrated correlation between temperature and PL lineshape of Si-quantum dots. The radiative and nonradiative relaxation and multi-exciton processes in methylammonium lead-halide MAPbI3 quantum dots are all found to be affected by quantum confinement, that positively affects PLQY. For nanostructures composed of heavy elements, such as CsPbBr3 colloidal quantum dots, the spin-orbit interaction is found to enable spin-forbidden transitions and to provide additional splitting between transitions energies of states involved in PL and affect rates and efficiencies of the PL. Nanostructures with periodicity such as nanowires and nanotubes provides specific spectral signatures, especially for materials that carry indirect gap feature in bulk form. Electronic transitions with change of electron’s momentum introduce additional pathways of nonradiative relaxation, which facilitate cooling of hot charge carriers.

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