DATE: Thursday, October 18, 2018
TIME: 12:00 PM - 01:00 PM
LOCATION:Auditorium (Room 0215) between building 2 & 3
ABSTRACT: Carbon materials are enabling components in a wide variety of current and emerging technologies. Carbon materials have enjoyed a special status in the general science community over the last 30 years through discoveries that have led to two Nobel Prizes and two Kavli Prizes for nanoscience. New carbon nanoforms (fullerenes, nanotubes, graphene) have played a central role in the nanotechnology movement, where they served as models of atomic perfection that inspired the discovery and development of other low-dimensional materials. This talk will give a brief overview of the history of carbon materials and a perspective on future research directions in the field. The talk will feature recent work from our laboratory using graphene oxide as an atomically-thin, sheet-like, giant molecular precursor for assembling new carbon architectures. Colloidal populations of GO nanosheets can be aligned, stacked, folded, crumpled, wrapped, gelled and/or deposited to create novel material structures not accessible through conventional routes. The talk will also give a status update and perspective on the important issue of nanocarbon safety, and will present a new tool for the safe design and selection of 1D carbons nanoforms based on quantitative geometric criteria. BIOGRAPHY: Robert Hurt is a Professor of Engineering at Brown University in Providence, Rhode Island and Director of the NIH-supported Superfund Research Program Center at Brown on environmental health. He received his Ph.D. from the Massachusetts Institute of Technology in chemical engineering and held a post at Sandia National Laboratories in Livermore, California before coming to Brown. He was the founding Director of Brown’s materials and nanosciences institute, IMNI, and served 2004-2010 as Editor of Carbon, and 2013-2018 as Editor-in-Chief. He has been Technical Program Chair for the International Carbon Conference and Graffin Lecturer of the American Carbon Society. He received the Tau Beta Pi teaching award at Brown, the Charles E. Pettinos Award of the American Carbon Society in 2013, and the 2017 Graphene Award of the International Association of Advanced Materials. He has co-authored over 140 scientific publications and his current research focuses on carbon materials, 2D materials, environmental nanotechnology, the nano-bio-interface, and safe material design.
LOCATION:Building 9, Lecture Hall 2
Stretchable electrical conductors and stretchable strain sensors are two key components in applications such as soft robotics, artificial soft skins, and wearable electronics. Very different approaches are usually implemented to design either conductors or sensors. Here, transformation of an electrically conductive material from a sensor to a conductor using electrical welding (e‐welding) is proposed. This method is demonstrated in the case of a thermoplastic polymer sponge decorated with silver nanowires. The sensor‐like behavior of the sponge is programmed by e‐welding into conductor‐like behavior, i.e., suppressing the gauge factor by 86%, without varying the density of the silver nanowires. An application of e‐welding in the fabrication of a sensor‐conductor hybrid material that may be applied as soft artificial skin in robotics is demonstrated.
DATE: Friday, October 19 - Saturday, October 27, 2018
TIME: 12:00 AM - 12:00 AM
DATE: Sunday, October 21, 2018
TIME: 12:00 PM - 12:30 PM
LOCATION:Auditorium Between Buildings 4 & 5
Abstract: Benzothiazol dicarboxylic derivative (BTDA) organic molecule, a well-known organic linker in various metal-organic frameworks synthesis, shows distinctive emission properties with respect to spectral, kinetics, and quantum yield changes upon concentration variations in various solvents. These changes are associated with the existence of two equilibria to form dimers and small-oligomer with high formation constants of 18,000 M-1, and 1.2 × 1013M-3, respectively, in DMF. These evolving species, dimers and oligomers, are formed through hydrogen bond formation between carboxylic acid groups present at the far-edge of the rod-like BTDA molecules. The estimated repeating number for such small-oligomer formation via bonded monomers is ca. four in DMF. Upon deprotonation, the dimers and oligomers can be easily collapsed to the initial monomer species, which confirms the role of hydrogen-bond on the observed phenomena. Theoretical studies confirm the existence of dimers and the role of hydrogen bonds on excited state dynamics. The formation of dimer and oligomer species in solution, suppress other non-radiative deactivating channels present in the monomer case, torsional motions, which leads to an increase in emission quantum yields. All these observed phenomena will be aiding towards better a understanding of the excited state photophysical properties of organic linkers used in a wide range of applications.
DATE: Monday, October 22, 2018
LOCATION:Building 9, Lecture Hall 2
Since the discovery of graphene in 2004, the research about two-Dimensional Materials (2DM) has attracted extensive attention worldwide. Mass production and commercial availability are prerequisites for the viability and wide applications of 2DM. Exfoliation of the bulk counterparts to give 2DM is one of the most promising ways to achieve large-scale production at an extremely low cost. In the exfoliation process, the ideal case is that the 2D flakes can be peeled from the bulk counterpart layer by layer. The resistance to overcome is the van der Waals attraction between adjacent 2D flakes. How to overcome the attraction force, peel the layer, and then achieve 2DM is intrinsically related to mechanics. Inspired by the mechanics involved in the exfoliation process, the talker will present his contribution to the production of 2DM (with a particular focus on graphene), in terms of the exfoliation assisted by sonication as well as pressure- and mixer-driven ﬂuid dynamics. The quality of the produced 2DM and the concentration and stability of the 2DM dispersions will be characterized by diverse methods including electronic microscopy and spectroscopy. Mechanics analysis reveals that the synergy of cavitation, shear effects, fragmentation, pressure release, collision, and turbulence contributes to the highly efficient exfoliation in fluid dynamics. In addition, a mixed-solvent strategy is developed for liquid exfoliation based on Hansen solubility parameters theory, whereby the cheap and low-boiling-point but ‘bad’ solvents such as water, ethanol, and acetone can be used. Finally, some example applications of the liquid-exfoliated 2DM are presented, including the composite reinforcement, the enhanced resistance to oxygen-atom corrosion, and the Li-ion battery electrodes. The research opens up the possibility of scalable, green, low-cost, and high-efficiency production of 2DM.
Dr. Min Yi is currently a Senior Postdoc and Principal Investigator (PI) at Technical University of Darmstadt (TU Darmstadt), Germany. He received his Bachelor and Ph.D. Degrees both in Engineering Mechanics from Beihang University, China in 2010 and 2015, respectively. He was a research assistant at the Mechanics of Functional Materials group in TU Darmstadt from 2013 to 2015. His research interest is in the broad area of mechanics and functional materials, with a particular focus on the mechanics inspired production of 2D materials and their applications, as well as multi-scale/physics modeling/simulations related to the nano/microstructure, property and additive manufacturing of functional materials. As a PI, he has been funded by DFG (Germany Research Foundation), TU Darmstadt, and State Key Laboratory for Strength and Vibration of Mechanical Structure. He has published over 45 authored or co-authored papers in top international journals including Nature Communications, npj Computational Materials, Acta Materialia, Physical Review Applied, etc., with 1170 citations to date. He has received a number of awards and honors, such as Beihang University outstanding PhD thesis (2016), Science and Technology Award in Chinese Society of Aeronautics and Astronautics (2016), Outstanding Graduate of Beijing (2010, 2015), National ‘Xu Zhilun’ Excellent Mechanics Student Award in The Chinese Society of Theoretical Applied Mechanics (2010), etc. He served as the reviewer of more than 20 international journals including Phys Rev Lett, Adv Mater, Adv Funct Mater, Phy Rev Appl, etc. He has delivered more than 20 presentations in international or local conferences, workshops, and seminars.
TIME: 01:00 PM - 03:00 PM
LOCATION:Building 5, Level 5, Room 5209
DATE: Wednesday, October 24, 2018
TIME: 04:15 AM - 05:15 AM
LOCATION:Lecture Hall 1 (2322), Engineering and Science Hall (Building 9)
Abstract: We study mathematical models and their finite element approximations for solving the coupled problem arising in the interaction between fluid in a poroelastic material and fluid in a fracture. The fluid flow in the fracture is governed by the Stokes/Brinkman equations, while the poroelastic material is modeled using the Biot system. We present several approaches to impose the continuity of normal flux, including an interior penalty method and a Lagrange multiplier method. A dimensionally reduced fracture model based on averaging the equations over the cross-sections will also be presented. Stability, accuracy, and robustness of the methods will be discussed.
Bio: Ivan Yotov is Professor in the Department of Mathematics at University of Pittsburgh. He served as Department Chair 2007-2017. His research interests are in numerical analysis of partial differential equations and large scale scientific computing with applications to flow in porous media, computational fluid dynamics, and biomedical problems. His recent work spans multiscale modeling of multiphysics systems of coupled flow and mechanics, advanced finite element and finite volume discretizations, scalable parallel solvers and preconditioners, stochastic modeling, uncertainty quantification, and parameter estimation.
Professor Yotov obtained his Ph.D. in Computational and Applied Mathematics from Rice University in 1996. He held a postdoctoral position at the Institute for Computational Engineering and Sciences at The University of Texas at Austin before joining University of Pittsburgh in 1998. He is an author of more than 90 scientific papers. He is Editor in Chief of Computational Geosciences and has served as Associate Editor of SIAM Journal on Numerical Analysis, Numerical Linear Algebra with Applications, and The Modeling and Computation for Flow and Transport, and as Guest Editor for a special issue of Computer Methods in Applied Mechanics and Engineering.
DATE: Thursday, October 25, 2018
The world’s energy demand is increasing at a rate of about 2% p.a., and this demand is estimated to have increased to 37% by 2040. Due to the continuing dominance of combustion in meeting this demand, concern over emissions has recently been heightened, and thus efficient, environmental-friendly combustion devices are needed to meet both energy demand and pollution regulations. Modern engines can operate in two main different modes: non-premixed combustion, in which fuel and oxidiser enter the combustion chamber separately, and premixed combustion, in which reactants are homogeneously mixed before being burned. The combustion in both cases is generally turbulent, as turbulence enhances the mixing between fuel and oxidiser, resulting in higher efficiencies. Due to concern for the environment, of these two combustion modes premixed combustion has recently captured industry interest, as high efficiency and low emissions can be achieved simultaneously. However, lean premixed combustion is prone to instabilities, thus additional effort is required to make a system operate in this condition. Moreover, practical devices operate in between turbulent premixed and non-premixed modes, a condition which is referred to as partially premixed combustion, posing additional challenges. For all of these reasons, the development of modern, advanced lean premixed combustion devices plays a key role in the whole energy sector. Computational Fluid Dynamics (CFD) is quickly assuming the role of a complementary tool for this development. Due to recent advances in High-Performance Computing (HPC), among existing techniques Large Eddy Simulation (LES) is becoming attractive as it can capture transient phenomena, but the computational cost can be quite high if the closures involved with this methodology are not robust in mimicking the relevant physics. Thus, it is of utmost importance to develop robust and computationally inexpensive models before LES can be used effectively in the design cycles of industrial devices such as aero-engines and power plants.This seminar will begin with an introduction to the state-of-the-art combustion modelling and its relevance for industrial applications. The specific modelling techniques developed at Cambridge and Loughborough Universities will be introduced and discussed, to then move to application and challenges in the simulation of industrial gas turbines and aero-engines. The seminar will then end with future challenges and perspectives for the research in the power generation sector.
LOCATION:Auditorium (Room 0215) between building 4 & 5
ABSTRACT: Contacts to transition metal dichalcogenides (TMDs) present several challenges in the context of realizing optimum device performance. In the case of traditional metal contacts, the TMD surface preparation method and the resultant condition plays a prominent role. Recently, the impact of the deposition ambient on contact resistance and the associated metal/TMD interfacial chemistry has been explored. It is found that the control of deposition under conditions where the residual gas pressure is controlled to minimize spurious surface reactions (viz. ultrahigh vacuum (UHV): Pdep ≤ 10-8 mbar) can result in a lower contact resistance for some metal/TMD systems. Comparing in-situ and ex-situ deposition in conjunction with surface/interface analysis of such interfaces reveals substantial differences in the interfacial chemical properties relative to contacts deposited under HV (Pdep ≤ 10-6 mbar) conditions more typical in device fabrication. In addition, the impact of post metal anneals are also presented. The chemical properties can be correlated to the interfacial band alignment and associated barriers with concomitant device measurements. BIOGRAPHY: Robert M. Wallace received his B.S. in Physics and Applied Mathematics in 1982 at the University of Pittsburgh where he also earned his M.S. (1984) and Ph.D. (1988) in Physics, under Prof. W. J. Choyke. From 1988 to 1990, he was a postdoctoral research associate in the Department of Chemistry at the Pittsburgh Surface Science Center under the late Prof. John T. Yates, Jr. In 1990, he joined Texas Instruments Central Research Laboratories as a Member of Technical Staff (MTS) in the Materials Characterization Branch of the Materials Science Laboratory and was elected as a Senior MTS in 1996. Dr. Wallace was then appointed in 1997 to manage the Advanced Technology branch in TI’s R&D which focused on advanced device concepts and the associated material integration issues. In 2003, he joined the faculty in the Erik Jonsson School of Engineering and Computer Science at the University of Texas at Dallas (UTD) as a Professor of Electrical Engineering and Physics. He is a founding member of the Materials Science and Engineering program at UTD. Dr. Wallace also has appointments in the Departments of Electrical Engineering, Mechanical Engineering, and Physics. He has authored or co-authored over 380 publications in peer reviewed journals and proceedings with over 23000 (32000) citations according to Scopus (Google Scholar), and is an inventor on 46 US patents. He was named Fellow of the AVS in 2007 and an IEEE Fellow in 2009 for his contributions to the field of high-k dielectrics in integrated circuits. Details can be found at: https://sites.google.com/view/robert-m-wallace